THE SUBJECT IS SOCIAL WORK Psychsocial history of a charector from a Essay

THE SUBJECT IS SOCIAL WORK Psychsocial history of a charector from a novel, She's Come Undone by Wally Lamb - Essay Example The character of Dolores Price is unlike any other because she drowns herself in her world of fantasy only to surface from time to time into a world of unrealistic problems. In the words of Dolores all these troubles â€Å"began somehow, in 1956 on the day our first television was delivered.† (Wally Lamb, 1992)She had no idea that something as simple as a television would lead her on the path of a personal tumultuous odyssey. The character of Dolores as presented by the author Wally Lamb, was vulnerable yet mysterious human being. To a great extent her family was responsible for the outcomes in her life. Her mother who was an emotionally disturbed person was quite fragile and battled with mental illness and therefore could not be of much help to Dolores. Her father was a lustful man who always threatened to leave the family. Her proud grandmother had a lot of pent up feelings and suffered deeply as she could not express them. Another person who did not belong to her family but was quite responsible for Dolores’ condition, was her handsome neighbor Jack Speight whose final betrayal throws the life of Dolores almost permanently off track. In this novel there are many cultural and social factors that play havoc in her life and brings her to a point of breaking. Quite frequently in the story we find Dolores making encounters with people who mirror the members of her family by whom she faced disappointment throughout her life. Beginning with her father, her path seemed to be guided towards dysfunctional relationships with men. In her quest to come to terms with her own identity, Dolores is victimized by her own circumstances and stands out as a character that is loathed as well as adored because of the unconventional way she presents herself. Dolores the protagonist is a tragic character who encounters tragedy after tragedy all through her life from the

Diffraction and Interference Essay Example for Free

Diffraction and Interference Essay Purpose: The aim of doing this experiment was to examine diffraction and interference effects of light passing through various apertures, and use the diffraction patterns obtained by single and double slit apertures to find the wavelength of the light source used. Theory: We know that light can be described by two theories, namely the particle theory and the wave theory of light, each having its own experimental proofs. In this experiment, we examine the interference and diffraction phenomena of light, both of which can be described by the wave theory of light. While interference is just the superposition of waves, diffraction is also any deviation from geometrical optics that results from the obstruction of a wavefront of light. In other words, diffraction is considering the double-slit experiment by taking into account the width of the slit openings, too. Another way of distinguishing between interference and diffraction is to consider the interfering beams in diffraction phenomena as originating from a continuous distribution of sources, whereas the interfering beams in interference phenomena as originating from a discrete number of sources. This way of treatment of interference and diffraction is a result of Huygens’ principle which states that every point of a given wavefront of light can be considered a source of secondary spherical wavelets. Hence, superposition occurs between these secondary waves emitted from different parts of the wavefront, taking into account both their amplitudes and phases. Diffraction effects can also be classified according to the mathematical approximations used in calculations. In the case of the light source and the observation screen being very far from the slit, relative to the slit width, the incident and diffracted waves are assumed to be plane and the diffraction type is called Fraunhofer, or far-field diffraction. In this case, as the viewing screen is moved relative to the aperture, the size of the diffraction pattern changes, but not the shape. We are going to use this kind of approximation in this experiment. We should keep in mind that the Huygens’ principle used to find the diffraction relations is itself an approximation. When calculating the single-slit Fraunhofer diffraction a rectangular aperture with a length much larger than its width is considered. In this case the intensity of the light reaching the screen at point P, at an angle ÃŽ ¸ is given by: Is=I0(sin2ÃŽ ±ÃŽ ±2) where ÃŽ ±=12kasinÃŽ ¸=Ï€asinÃŽ ¸ÃŽ » In the above relations I0 is the intensity at the middle of the central maxima and a is the slit width. Hence, by taking the limit as ï„Æ'→0, we observe that this pattern attains its maximum at ÃŽ ¸=0. Similarly, equating ï„Æ'=mÏ€, we obtain the minima of the pattern and we get the following relation for this case: nÃŽ »=asinÃŽ ¸ where n=1,2,3,†¦ For small angles we can make the sinÃŽ ¸=tanÃŽ ¸ approximation and, calling L the distance between the slit and the screen, we can get y=LsinÃŽ ¸, where y is the distance from the central maximum to the observation point. For this case, we conclude that on the screen, the irradiance is a maximum at ÃŽ ¸=0, hence y=0, and it drops to zero at values of y such that y=ÃŽ »La . Therefore, we can find ÃŽ » using this relation. (Here, y is the average distance between adjacent minima). When we regard the double-slit diffraction we see that we have to do with two different terms, one of which belongs to the interference pattern, and the other to the diffraction pattern. If we ignore the effect of the slit widths, we get the intensity of the pattern given by only the interference term as I=4I0cos2ÃŽ ², where ÃŽ ²=(Ï€bÃŽ »)sinÃŽ ¸. Here, ÃŽ ¸ is the angle of observation and b is the slit separation. Nevertheless, since the intensity from a single slit depends on the angle ÃŽ ¸ through diffraction, we should take into account the diffraction pattern, too. Now, the intensity is given by: I=4I0(sin2ÃŽ ±ÃŽ ±2)cos2ÃŽ ² In this case ï„Æ' is again ÃŽ ±=12kasinÃŽ ¸=Ï€asinÃŽ ¸ÃŽ ». Hence, we conclude that in double slit diffraction the intensity is the product of the interference and diffraction patterns. By analyzing the intensity relation, we observe that an interference minimum occurs whenever ÃŽ ²=(n+1/2)Ï€ for n=0,1,2,3,†¦, and an interference maxima occurs whenever ÃŽ ²=nÏ€, again for n=0,1,2,†¦ Using the approximation sinÃŽ ¸=tanÃŽ ¸, we obtain y=LsinÃŽ ¸, and y=ÃŽ »Lb, where y is the average distance between either adjacent maxima or minima. Data and Results: Part A: Single Slit Pattern| A| B| C| Width of the slit, a| 410-5m| 810-5m| 1610-5m| Distance slit-screen, L| 1m| 1m| 1m| Average dist btw minima, y| 1.67 cm| 0.75 cm| 0.45 cm| ÃŽ »=ay/L| 668 nm| 600 nm| 720 nm| Error ∆y on y| 0.08173 cm| 0.138 cm| 0.0548 cm| Error ∆Î » on ÃŽ »=a∆y/L| 32.7 nm| 110 nm| 87.7 nm| ÃŽ »=ÃŽ »Ã‚ ±Ã¢Ë†â€ ÃŽ »| 635.5 nm| 710 nm| 632.3 nm| | y1| y2| y3| y4| y5| y6| A| 1.8| 1.6| 1.7| 1.7| 1.6| 1.6| B| 0.5| 0.8| 0.8| 0.8| 0.9| 0.7| C| 0.5| 0.5| 0.5| 0.4| 0.4| 0.4| The error on y is found using the relation below: ∆y=i=1N(yi-y)N-1 Part B: Double Slit Pattern| D| E| F| Width of the slit, a| 810-5m| 810-5m| 410-5m| Slit separation, b| 510-4m| 2.510-4m| 2.510-4m| Distance slit-screen, L| 1m| 1m| 1m| Average dist btw minima, y| 0.00160 m| 0.00300 m| 0.00155 m| ÃŽ »=by/L| 800 nm| 750 nm| 387.5 nm| Error ∆y on y| 0.000342m| 0.000524m| 0.000342m| Error ∆Î » on ÃŽ »=b∆y/L| 171 nm| 131 nm| 85.5 nm| ÃŽ »=ÃŽ »Ã‚ ±Ã¢Ë†â€ ÃŽ »| 629 nm| 619 nm| 473 nm| y| D| E| F| 1| 0.138| 0.110| 0.053| 2| 0.141| 0.106| 0.051| 3| 0.143| 0.101| 0.048| 4| 0.146| 0.095| 0.045| 5| 0.148| 0.090| 0.043| 6| 0.151| 0.086| 0.040| 7| 0.154| | 0.038| 8| 0.156| | 0.035| 9| | | 0.033| We calculated the difference between each successive data to obtain the displacement. Then, we multiplied each displacement value with a factor of (21.5/34.5) because the scale of the linear translator and the interface were not equal. Having done this we calculated the average distance. The error on y is found again by using the relation ∆y=i=1N(yi-y)N-1 Discussion and Conclusion: In part A we considered interference and diffraction pattern of a single slit opening for three different slits. We measured the distance between the source and the slit to be 1m and we used the relations found in the theory part in order to find the wavelength of the light source used. We found the average distance between minima to be 1.67 cm for slit A, 0.75 cm for slit B and 0.45 cm for slit C. Hence, we found the wavelength of the light source to have values of 668 nm for slit A, 600nm for slit B and 720nm for slit C. However, after calculating the error in the average distance and using this error, the wavelengths turned out to be 635.5nm for slit A, 710nm for slit B and 632.3nm for slit C. We know that theoretically the wavelength is expected to be 650 ±10nm. Our experimental values, despite the fact they are close to, do not fit totally to the expected theoretical ones. Hence, we argue that any discrepancy in the values found is a result of the imprecise equipment used, especially the light sensor. Furthermore, we claim that these discrepancies are also a result of the fact that we had to move the linear translator with our hand slowly enough so that the detector could detect the intensity peak and the other maxima. Hence, it is very much likely that we could not carry this process out precisely enough as it is required in order to have correct data, since we are human beings and it is impossible for us to achieve such a thing. We also think that the light coming from the surrounding might have had a negative effect on our results since the room where the experiment was carried out was not evacuated well enough. Moreover, we point out that the relations between wavelength, distance between minima and slit width used to find the wavelength and the Huygens’ principle itself are all approximations, since as it was stated in the theory part, we u sed far field mathematical approximations in order to obtain these relations. In part B, we used a double slit opening in order to observe the interference and diffraction pattern. In this case both the slit width and the slit separation have an effect when finding the intensity at a certain point. However, in the relations used to find the wavelength we considered only the slit separation b. In this part, after calculating the error in displacement and using this in ÃŽ », we found the wavelength values to be of 629nm for slit D, 619nm for slit E and 473nm for slit F. We observe that, except for slit F, these values of ÃŽ » agree with the values found in part A. We claim that the discrepancies in this part are a result of the same reasons causing the discrepancies in part A. As for the case of slit F where ÃŽ » turned out to be 473nm (much smaller than the theoretical value) we think that the main reason for such a result is the change in width of the slit, which in this case, unlike the other two cases, is 0.04mm. This leads us to conclude that, as expected t heoretically, the width of the slit also affects the intensity pattern, and in these cases more precise relations should be used in order to obtain correct data. Applications: Interference and diffraction phenomena of light have found a quite large application in science and technology. Understanding these phenomena has led to understanding the world around us and being able to use it in a better way in order to fulfill our needs. Among the most important applications of diffraction for example, is the fact that it is used to obtain accurate information about the atomic scale structure of the matter around us. Since the number of atoms or molecules inside a crystal is arranged in such a way that it resembles a grating with very thin spacing, diffraction phenomena leads to understanding the insights of each crystal structure. Diffraction phenomena was also used to learn that the sodium and chloride ions are bonded in a lattice fashion and not molecules, to distinguish between different cubic lattice, to analyze all kinds of materials, even biological samples, etc. Using diffraction interesting things such as hair thickness can also be measured .The interference phenomenon, on the other hand, is used to make highly-wavelength specific mirrors for lasers. Furthermore, interference is the reason why soap bubbles appear colorful. Many other optical coatings owe their optical properties to the interference phenomena. An example of this is the antireflection coatings on lenses that we use everyday. Another application of interference is holography, which is a way of reconstructing three dimensional images with laser light. Perhaps the most fascinating application of interference is to create holograms. This is done by reflecting a coherent light source, such as a laser, off of an object onto a special film. The interference patterns created by the reflected light are what result in the holographic image, which can be viewed when it is again placed in the right sort of lighting. Moreover, diffraction and interference can be observed when an atom passes through a standard light wave and its position is localized. In this case, the localization can be thought of as the creation of virtual slits leading to the above mentioned phenomena. Diffraction is also used to understand the insights of the ionosphere. All in all, by doing this experiment we learned the importance of the phenomenon of interference and diffraction in our lives. References: http://online.physics.uiuc.edu/courses/phys214/spring09/Lectures/Lect04.pdf http://bigbro.biophys.cornell.edu/~toombes/Science_Education/Laser_Diffraction/Diffraction_Lesson.pdf http://answers.yahoo.com/question/index?qid=20080509124425AAyW8bl http://physics.about.com/od/mathematicsofwaves/a/interference.htm URL: http://link.aps.org/doi/10.1103/PhysRevLett.68.472

Model for Predicting Fatigue Life of Nanomaterials

Model for Predicting Fatigue Life of Nanomaterials Introduction In the past, the primary function of micro-systems packaging was to provide input/output (I/O) connections to and from integrated circuits (ICs) and to provide interconnection between the components on the system board level while physically supporting the electronic device and protecting the assembly from the environment. In order to increase the functionality and the miniaturization of the current electronic devices, these IC devices have not only incorporated more transistors but have also included more active and passive components on an individual chip. This has resulted in the emerging trend of a new convergent system[1] Currently, there are three main approaches to achieving these convergent systems, namely the system-on-chip (SOC), system-in-package (SIP) and system on package (SOP). SOC seeks to integrate numerous system functions on one silicon chip. However, this approach has numerous fundamental and economical limitations which include high fabrication costs and integration limits on wireless communications, which due to inherent losses of silicon and size restriction. SIP is a 3-D packaging approach, where vertical stacking of multi-chip modules is employed. Since all of the ICs in the stack are still limited to CMOS IC processing, the fundamental integration limitation of the SOC still remains. SOP on the other hand, seeks to achieve a highly integrated microminiaturized system on the package using silicon for transistor integration and package for RF, digital and optical integration[1] IC packaging is one of the key enabling technologies for microprocessor performance. As performance increases, technical challenges increase in the areas of power delivery, heat removal, I/O density and thermo-mechanical reliability. These are the most difficult challenges for improving performance and increasing integration, along with decreasing manufacturing cost. Chip-to-package interconnections in microsystems packages serve as electrical interconnections but often fail by mechanisms such as fatigue and creep. Furthermore, driven by the need for increase the system functionality and decrease the feature size, the International Technology Roadmap for Semi-conductors (ITRS) has predicted that integrated chip (IC) packages will have interconnections with I/O pitch of 90 nm by the year 2018 [2]. Lead-based solder materials have been used for interconnections in flip chip technology and the surface mount technology for many decades. The traditional lead-based and lead-free solder bumps will not satisfy the thermal mechanical requirement of these fine pitches interconnects. These electronic packages, even under normal operating conditions, can reach a temperature as high as 150C. Due to differences in the coefficient of thermal expansion of the materials in an IC package, the packages will experience significant thermal strains due to the mismatch, which in turn will cause lead and lead-free solder interconnections to fail prematurely. Aggarwal et al [3] had modeled the stress experienced by chip to package interconnect. In his work, he developed interconnects with a height of 15 to 50 micrometre on different substrate using classic beam theory. Figure 1 shows the schematic of his model and a summary of some of his results. Although compliant intrerconect could reduces the stress experienced by the interconnect, it is still in sufficient. Chng et al. [4] performed a parametric study on the fatigue life of a solder column for a pitch of 100micrometre using a macro-micro approach. In her work, she developed models of a solder column/bump with a pad size of 50micrometre and heights of 50 micrometre to 200 micrometre. Table I shows a summary of some of her results. Table 1.1: Fatigue life estimation of solder column chip thickness (micrometre) 250 640 640 640 board CTE (ppm/K) 18 18 10 5 solder column height (micrometre) Fatigue life estimation/cycle) 50 81 N.A 171 3237 100 150 27 276 3124 150 134 31 518 4405 200 74 38 273 5772 It can be seen from Table 1.1 that the fatigue lives of all solder columns are extremely short. Apart from the 5ppm/K board where there is excellent CTE matching, the largest fatigue life of the solder column is only about 518 cycles. As expected, the fatigue life increases significantly when the board CTE decreases from 18ppm/K to 10ppm/K and as the height increases from 50micrometre to 200micrometre.This is mainly due to the large strain induced by the thermal mismatch as shown in Figure 1.2. The maximum inelastic principal strain was about 0.16 which exceeds the maximum strain that the material can support. Although the fatigue life of the chip to package interconnection can be increases by increasing the interconnects height, it will not be able to meet the high frequency electrical requirements of the future IC where they need to be operating at a high frequencies of 10-20 GHz and a signal bandwidth of 20 Gbps, By definition, nanocrystalline materials are materials that have grain size less than 100nm and these materials are not new since nanocrystalline materials have been observed in several naturally-occurring specimens including seashells, bone, and tooth enamel [5, 6]. However, the nanocrystalline materials have been attracting a lot of research interest due to its superior mechanical and electrical properties as compared to the coarse-grained counterpart. For example, the nano-crystalline copper has about 6 times the strength of bulk copper [7]. Furthermore, the improvement in the mechanical properties due to the reduction in grain size has been well-documented. Increase in strength due to the reduction in grain-size is predicted by the Hall-Petch relationship which has also been confirmed numerically by Swygenhoven et al [8] and was first demonstrated experimentally by Weertman [9]. The implantation of nanocrystalline copper as interconnect materials seems to be feasible from the processing viewpoint too. Copper has been used as interconnects materials since 1989 whereas nano-copper has also been widely processed using electroplating and other severe plastic deformation techniques in the past few years. For instance, Lu et al. [10] have reported electroplating of nano-copper with grain size less than 100 nm and electrical conductivity comparable to microcrystalline copper. Furthermore, Aggarwal et al [11] have demonstrated the feasibility of using electrolytic plating processes to deposit nanocrystalline nickel as a back-end wafer compatible process. However, there are certain challenges regarding implantation of nanocrystalline copper as interconnects materials. As discussed above, nanocrystalline copper have a high potential of being used as the next generation interconnect for electronic packaging. However, it is vital to understand their material properties, deformation mechanisms and microstructures stability. Although the increase in strength due to the Hall-Petch relationship which has also been confirmed numerically and experimentally by Weertman [9], the improvement in the fatigue properties is not well documented and no model has been established to predict/characterize these nano materials in interconnection application; conflicting results regarding the fatigue properties have also been reported. Kumar et al [12] reported that for nano-crystalline and ultra-fine crystalline Ni, although there is an increase in tensile stress range and the endurance limit, the crack growth rate also increases. However, Bansal et al. [7] reported that with decreasing grain size, the tensile stress range increases but the crack growth rate decreases substantially at the same cyclic stress intensity range. Thus, nanostructured materials can potentially provide a solution for the reliability of low pitch interconnections. However, the fatigue resistance of nanostructured interconnections needs to be further investigated. Since grain boundaries in polycrystalline material increases the total energy of the system as compare to perfect single crystal, it will resulted in a driving force to reduce the overall grain boundary area by increasing the average grain size. In the case of nanocrystalline materials which have a high volume fraction of grain boundaries, there is a huge driving force for grain to growth and this presented a presents a significant obstacle to the processing and use of nanocrystalline copper for interconnect applications. Millet et al [13] have shown, though a series of systematic molecular dynamics simulations, grain growth in bulk nanocrystalline copper during annealing at constant temperature of 800K can be impeded with dopants segregated in the grain boundaries regions. However, it has been observed that stress can trigger grain growth in nanocrystalline materials [14] and there is no literature available on impeding stress assisted grain growth. There is an impending need to investigate the impediment to grain growth caused by the dopant during fatigue/stress assisted grain growth Dissertation Objectives The goal of present project is to develop a model for the fatigue resistance of nano-materials that have been shown to have superior fatigue resistance. Accordingly, the following research objectives are proposed. Develops a model for predicting fatigue life of nanostructured chip-to-package copper interconnections Develops a fundamental understanding on the fatigue behavior of nanocrystalline copper for interconnect application Addresses the issue on the stability of nanocrystalline materials undergoing cyclic loading Overview of the Thesis The thesis is organized so that past research on nanocrystalline materials forms the basis of the understanding and new knowledge discovered in this research. Chapter 2 reviews much of the pertinent literature regarding nanocrystalline materials, including synthesis, deformation mechanisms, and grain growth. Chapter 3 describes a detailed overview of the technical aspects of the molecular dynamics simulation method including inter-atomic potentials, time integration algorithms, the NVT NPT, and NEPT ensembles, as well as periodic boundary conditions and neighbor lists. Include in this chapter is the algorithms for creating nanocrystalline materials used in this dissertations.. Chapter 4 describes the simulation procedure designed to investigate and develop the long crack growth analysis. The results of the long crack growth analysis will be presented at the end of Chapter 4. Chapter 5 presents the result and discussion on mechanical behavior of single and nanocrystalline copper subjected to monotonic and cyclic loading whereas Chapter 6 presents the result and discussion on the impediment to grain growth caused by the dopant during fatigue/stress assisted grain growth. Finally, conclusions and recommendations for future work are presented in Chapter 5. Chapter 2 This chapter offers an expanded summary of the literature published with regards to the fabrication methods, characterization, and properties of nanocrystalline materials in addition to a description of existing interconnect technology. 2.1 Off-Chip Interconnect Technologies Chip-to-package interconnections in microsystems packages serve as electrical interconnections but they will often failed by mechanisms such as fatigue and creep. Furthermore, driven by the need for increase the system functionality and decrease the feature size, the International Technology Roadmap for Semi-conductors (ITRS) has predicted that interconnections of integrated chip (IC) packages will have a I/O pitch of 90 nm by the year 2018 [2]. The International Technology Roadmap for Semiconductors (ITRS) roadmap is a roadmap that semiconductor industry closely follows closely and its projects the need for several technology generations. The package must be capable of meeting these projections in order for it to be successful. This section reviews some of the current interconnect technology. Wire bonding [15] as shown in Figure 2.1, is generally considered as one of the most simple, cost-effective and flexible interconnect technology. The devices on the silicon die are (gold or aluminum) wire bonded to electrically connect from the chip to the wire bond pads on the periphery. However, the disadvantages of wire bonding are the slow rate, large pitch and long interconnect length and hence this will not be suitable for high I/O application. Instead of wires in the wire bonding, tape automated bonding (TAB) is an interconnect technology using a prefabricated perforated polyimide film, with copper leads between chip and substrate. The advantage of this technology is the high throughput and the high lead count. However, it is limited by the high initial costs for tooling. An alternative to peripheral interconnect technology is the area-array solution, as shown in Figure 2.3, that access the unused area by using the area under the chip. In area-array packaging, the chip has an array of solder bumps that are joined to a substrate. Under-fill is then fills the gap between the chip and substrate to enhance mechanical adhesion. This technology gives the highest packaging density methods and best electrical characteristics of all the avaiable interconnection technology. However, not only is its initial cost is high, it requires a very demanding technology to establish and operate. With the need for higher I/O density, compliant interconnects have been developed to satisfy the mechanical requirements of high performance micron sized interconnects. The basic idea is to reduce shear stress experienced by the interconnects through increasing their height or decreasing of its shear modulus (i.e. increases in their compliant) and hence the name compliant interconnects. Some of recent research in compliant interconnects include Tesseras Wide Area Vertical Expansion, Form Factors Wire on Wafer and Georgia Institute of Technologys Helix interconnects [17-19] as shown in Figure 2.4. Although compliant interconnects can solve the problem of mechanical reliability issue, they are done at the expense of the electrical performance. Since there is a need to reduce the packages parasitic through a decrease line delays, there is a need to minimize the electrical connection length in order to increase the system working frequency. Hence, compliant interconnect may not meet the high electrical frequency requirements of future devices. Figure 2.4: (a) Wide Area Vertical Expansion, (b) Wire on Wafer and (c) G-Helix [17-19] Lead and lead-free solders typically fail mechanical when scaled down to less than to a pitch of 100 mm. Compliant interconnections, on the other hand, do not meet the high frequency electrical requirements. The Microsystems Packaging Research Center at Georgia institute of Technology had demonstrated the feasibility of using re-workable nanostructure interconnections. Aggarwal et al [20] had show that nanostructured nickel interconnections, through a Flip Chip test vehicle, was able to improve the mechanical reliability while maintaining the shortest electrical connection length. However, the main disadvantages of this method was the significant signal loss at high frequency signal of nanocrystalline nickel [21]. As discussed above, nanostructure interconnects technology is the most promising interconnect technology to best meet the stringent mechanical and electrical requirement of next generation devices. However, there is a need of an alternate materials and a sensible choice of materials in this case would be nanocrystalline copper for its high strength material with superior electrical conductivity. Hence, it would be beneficial to use nanocrystalline-copper as material for the nanostructure interconnects. Due to the tendency for the grain to grow, there is a need to stabilize the grain growth in nanocrystalline copper before using it could be considered as a potential candidate for nanostructure interconnect. 2.2 Nanocrystalline material Nanocrystalline materials are polycrystalline materials with an average grain size of less than 100 nm [22]. Over the past decade , new nanocrystalline or nanostructured materials with key microstructural length scales on the order of a few tens of nanometers has been gaining a lot of interest in the material science research society. This is mainly due to its unique and superior properties, as compared to their microcrystalline counterparts which includes increased strength [22] and wear resistance [23]. These unique properties are due to the large volume fraction of atoms at or near the grain boundaries. As a result, these materials have unique properties that are representative of both the grain boundary surface characteristics and the bulk. Recent advances in synthesis and processing methodology for producing nanocrystalline materials such as inert gas condensation [24], mechanical milling [25, 26], electro-deposition [27], and severe plastic deformation [28] have made it possible to produce sufficient nanocrystalline materials for small scale application. 2.2.1 Synthesis Inert gas condensation, the first method used to synthesis bulk nanocrystalline [29], consists of evaporating a metal inside a high-vacuum chamber and then backfilling the chamber with inert gas [30]. These evaporated metal atoms would then collide with the gas atoms, causing them to lose kinetic energy and condenses into powder of small nano-crystals. These powders are then compacted under high pressure and vacuum into nearly fully dense nanocrystalline solids. The grain size distribution obtained from this method is usually very narrow. However, the major draws back of this method are its high porosity levels and imperfection bonding. Grain coarsening also occurs due to the high temperature during the compaction stage [31]. Mechanical milling consists of heavy cyclic deformation in powders until the final composition of the powders corresponds to a certain percentages of the respective initial constituents [25, 26]. A wide grain size distribution is obtained by this method. This technique is a popular method to prepare nanocrystalline materials because of its applicability to any material and simplicity. However, their main drawback includes contamination and grain coarsening during the consolidation stage. Electro-deposition consists of using electrical current to reduce cations of a desired material from a electrolyte solution and coating a conductive object on the substrate. Electro-deposition has many advantages over processing techniques and this includes its applicability to a wide variety of materials, low initial capital investment requirements and porosity-free finished products without a need for consolidation processing [27]. Furthermore, Shen et al. [32] and Lu et al.[33] had recently show that the right electro-deposition condition can produce a highly twinned structure which leads to enhanced ductility. The main drawback of this method is it is the difficulty to achieve high purity. Severe plastic deformation, such as high-pressure torsion, equal channel angular extrusion (ECAE), continuous confined shear straining and accumulative roll-bonding, uses extreme plastic straining to produce nanocrystalline materials by mechanisms such as grain fragmentation, dynamic recovery, and geometric re-crystallization [34]. It is the only technology that transformed conventional macro-grained metals directly into nanocrystalline materials without the need of potentially hazardous nano-sized powders. This is achieved by introducing very high shear deformations into the material under superimposed hydrostatic pressure. Two of the most commonly used methods are high-pressure torsion and ECAE [35]. In the study of the effect of ECAE on the microstructure of nanocrystalline copper, Dalla Torre et al [36] observed that the grains become more equi-axial and randomly orientation as the number of passes increases, as shown in Figure 2.5 Figure 2.5: Microstructure of ECAE copper subjected to (a) 1 passes (b) 2 passes (c) 4 passes (d) 8 passes (e) 12 passes and (f) 16 passes [36] 2.2.2 Mechanical Behavior of nanocrystalline materials Due to the small grain size and high volume fraction of grain boundaries, nanocrystalline materials exhibit significantly different properties and behavior as compared to their microcrystalline counterpart. The structure and mechanical behavior of nanocrystalline materials has been the subject of a lot of researchers interests both experimentally [37-43] and theoretically [44-50]. This section reviews the principal mechanical properties and behavior of nanocrystalline materials. 2.2.2.1 Strength and ductility Recent studies of nanocrystalline metals have shown that there is a five to ten fold increases in the strength and hardness as compared to their microcrystalline state [7, 36, 37, 51, 52]. This increase in the strength is due to the presence of grain boundaries impeding the nucleation and movement of dislocations. Since decreasing grain boundary size increases the number of barrier and the amount of applied stress necessary to move a dislocation across a grain boundary, this resulted in a much higher yield strength. The inverse relationship between grain size and strength is characterized by the Hall-Petch relationship [53, 54] as shown in equation (2.1). Eq (2.1) In equation (2.1), s is the mechanical strength, k is a material constant and d is the average grain size. Hence, nanocrystalline materials are expected to exhibit higher strength as compared to their microcrystalline counterpart. Figure 2.6 and Figure 2.7 show the summary of hardness and yield strength from tensile test that are reported in the literature. Indeed, hardness and yield strength of copper with a grain size of 10nm (3GPa) can be one order higher than their microcrystalline counterpart. To the larger specimens. Derivation from Hall-Petch relationship begins as the grain size approaches 30nm where the stresses needed to activate the dislocation multiplication via Frank-Read sources within the grains are too high and the plastic deformation is instead accommodated by grain boundaries sliding and migration.[12]. Furthermore, as the grain size reduces, the volume fraction of the grain boundaries and the triple points increases. Material properties will be more representative of the grain boundary activity [64] and this will resulting the strength to be inversely proportional to grain size instead of square roots of the grain size as predicted by Hall Petch relation [65]. Further reduction in the grain size will result in grain boundaries processes controlling the plastic deformation and reverse Hall-Petch effect, where the materials soften, will take place. Although sample defects had been account for the earlier experimental observation of reverse Hall-Petch effect[24], Swygenhoven et al [66] and Schiotz et al [47], using molecular simulation, was able to showed that nanocrystalline copper had the highest strength (about 2.3GPa ) at a grain size of 8nm and 10-15nm respectively. Conrad et al [67] pointed out that below this critical grain size, the mechanisms shifted to grain boundary-mediated from dislocation-mediated plasticity and this causes the material to become dependent on strain rate, temperature, Taylor orientation factor and presence of the type of dislocation. The yield stress of nanocrystalline copper was highly sensitive to strain rate even though it is a fcc materials. The strain rate sensitivity, m, in equation 2.2 a engineering parameter which measured the dependency of the strain rate and Figure 2.8 shows a summary of m as a function of grain size for copper specimen in the literature [51, 68-70]. Due to high localized dislocation activities at the grain boundaries which results in enhanced strain rate sensitivities in nanocrystalline materials, m increases drastically when the grain size is below 0.1 mm as shown in Figure 2.8. (2.2) Room temperature strain rate sensitivity was found to dependent on dislocation activities and grain boundaries diffusion [52, 71, 72]. Due to the negligible lattice diffusion at room temperature, the rate limiting process for microcrystalline copper was the gliding dislocation to cutting through forest dislocation, resulting in low strain rate sensitivities. However, due to the increasing presence of obstacles such as grain boundaries for nanocrystalline materials, the rate limiting process for smaller grain size was the interaction of dislocation and the grain boundaries, which is strain rate and temperature dependence. By considering the length scale of the dislocation and grain boundaries interaction, Cheng et al [52] proposed the following model for strain rate sensitivities . (2.3) z is the distance swept by the dislocation during activation, r is the dislocation density and a, a and b are the proportional factors. With this model, they will be able to predict higher strain rate sensitivities for nanocrystalline material produced by severe plastic deformation as compared to other technique. Since the twin boundaries in nanocrystalline or ultra fine grain copper served as a barriers for dislocation motion and nucleation which led to highly localized dislocations near the twin boundaries, the strain rate sensitivity of copper with high density of coherent twin boundaries was found to be higher than those without any twin boundaries [33]. Lastly, the increase enhanced strain rate sensitivity in nanocrystalline copper had been credited for it increases in strength and ductility. For example, Valiev et al [60] credited the enhanced strain rate sensitivity of 0.16 for the high ductility. In addition to a strong dependency on the strain rate, strength in nanocrystalline materials was also highly dependent on the temperature. Wang et al [73] observed that the yield strength for ultra fine grain copper with a grain size of 300nm increases from approximately 370MPa to 500MPa when the temperature reduces from room temperature to 77k. The authors attributed this increase in yield strength due to the absence of additional thermal deformation processes at 77k. This is consistent with Huang et al [74] observation where the temperature dependence of nanocrystalline copper with an increase in hardness of nanocrystalline copper with lowering the temperature is noted Ductility is another important characteristic of nanocrystalline materials. In microcrystalline materials, a reduction in grain size will increase the ductility due to the presence of grain boundaries acting as effective barriers to the propagation of micro-cracks[75]. However, nanocrystalline copper showed a lower strain to failure than that of their microcrystalline counterparts and this lacks in ductility was attributed to the presence of processing defects [76]. Recent advanced in processing of nanocrystalline materials offer materials with fairly good ductility in additional to ultra-high strength. Lu et al [10] reported that nanocrystalline copper with minimal flaw produced via electro-deposition had an elongation to fracture of 30%. Furthermore, Youssef et al [77] observed a 15.5% elongation to failure for defect free nanocrystalline copper produced via mechanical milling. Hence, it was possible for nanocrystalline copper to be both strong and ductile if the processing artifacts are minimized. The failure are usually consists of dimples several time larger than their grain size was normally found on the failure morphology of nanocrystalline materials and Kumar et al [78] presented the following model for initiation and hence the eventual failure of nanocrystalline materials. Furthermore, the presence of shear region was found to be due to shear localization since the ratio of strain hardening rate to prevailing stress was usually small [79, 80]. Figure 2.9: Schematic illustration of fracture in nanocrystalline material postulated by Kumar et al [78] 2.2.2.2 Creeps Nanocrystalline materials are expected to creep during room temperature. This is because Due to the higher fraction of grain boundaries and triple junctions, self diffusivity of nanocrystalline material had been shown to increase by an order of three as compared to microcrystalline copper [81]. Since creep behavior was dependent on grain size and diffusivity, with creep rate increases with an increase in diffusivity or a decrease in grain size, the creep temperature for nanocrystalline copper was known to be a small fraction of melting temperature (about 0.22 of its melting points). Furthermore, since creep had always been cited as one of the reason for grain size softening in nanocrystalline materials, creeps were other important mechanical properties of nanocrystalline materials that had been gaining a lot of researchers attention. Due to the high volume fraction of grain boundaries and enhanced diffusivity rate Model for Predicting Fatigue Life of Nanomaterials Model for Predicting Fatigue Life of Nanomaterials Introduction In the past, the primary function of micro-systems packaging was to provide input/output (I/O) connections to and from integrated circuits (ICs) and to provide interconnection between the components on the system board level while physically supporting the electronic device and protecting the assembly from the environment. In order to increase the functionality and the miniaturization of the current electronic devices, these IC devices have not only incorporated more transistors but have also included more active and passive components on an individual chip. This has resulted in the emerging trend of a new convergent system[1] Currently, there are three main approaches to achieving these convergent systems, namely the system-on-chip (SOC), system-in-package (SIP) and system on package (SOP). SOC seeks to integrate numerous system functions on one silicon chip. However, this approach has numerous fundamental and economical limitations which include high fabrication costs and integration limits on wireless communications, which due to inherent losses of silicon and size restriction. SIP is a 3-D packaging approach, where vertical stacking of multi-chip modules is employed. Since all of the ICs in the stack are still limited to CMOS IC processing, the fundamental integration limitation of the SOC still remains. SOP on the other hand, seeks to achieve a highly integrated microminiaturized system on the package using silicon for transistor integration and package for RF, digital and optical integration[1] IC packaging is one of the key enabling technologies for microprocessor performance. As performance increases, technical challenges increase in the areas of power delivery, heat removal, I/O density and thermo-mechanical reliability. These are the most difficult challenges for improving performance and increasing integration, along with decreasing manufacturing cost. Chip-to-package interconnections in microsystems packages serve as electrical interconnections but often fail by mechanisms such as fatigue and creep. Furthermore, driven by the need for increase the system functionality and decrease the feature size, the International Technology Roadmap for Semi-conductors (ITRS) has predicted that integrated chip (IC) packages will have interconnections with I/O pitch of 90 nm by the year 2018 [2]. Lead-based solder materials have been used for interconnections in flip chip technology and the surface mount technology for many decades. The traditional lead-based and lead-free solder bumps will not satisfy the thermal mechanical requirement of these fine pitches interconnects. These electronic packages, even under normal operating conditions, can reach a temperature as high as 150C. Due to differences in the coefficient of thermal expansion of the materials in an IC package, the packages will experience significant thermal strains due to the mismatch, which in turn will cause lead and lead-free solder interconnections to fail prematurely. Aggarwal et al [3] had modeled the stress experienced by chip to package interconnect. In his work, he developed interconnects with a height of 15 to 50 micrometre on different substrate using classic beam theory. Figure 1 shows the schematic of his model and a summary of some of his results. Although compliant intrerconect could reduces the stress experienced by the interconnect, it is still in sufficient. Chng et al. [4] performed a parametric study on the fatigue life of a solder column for a pitch of 100micrometre using a macro-micro approach. In her work, she developed models of a solder column/bump with a pad size of 50micrometre and heights of 50 micrometre to 200 micrometre. Table I shows a summary of some of her results. Table 1.1: Fatigue life estimation of solder column chip thickness (micrometre) 250 640 640 640 board CTE (ppm/K) 18 18 10 5 solder column height (micrometre) Fatigue life estimation/cycle) 50 81 N.A 171 3237 100 150 27 276 3124 150 134 31 518 4405 200 74 38 273 5772 It can be seen from Table 1.1 that the fatigue lives of all solder columns are extremely short. Apart from the 5ppm/K board where there is excellent CTE matching, the largest fatigue life of the solder column is only about 518 cycles. As expected, the fatigue life increases significantly when the board CTE decreases from 18ppm/K to 10ppm/K and as the height increases from 50micrometre to 200micrometre.This is mainly due to the large strain induced by the thermal mismatch as shown in Figure 1.2. The maximum inelastic principal strain was about 0.16 which exceeds the maximum strain that the material can support. Although the fatigue life of the chip to package interconnection can be increases by increasing the interconnects height, it will not be able to meet the high frequency electrical requirements of the future IC where they need to be operating at a high frequencies of 10-20 GHz and a signal bandwidth of 20 Gbps, By definition, nanocrystalline materials are materials that have grain size less than 100nm and these materials are not new since nanocrystalline materials have been observed in several naturally-occurring specimens including seashells, bone, and tooth enamel [5, 6]. However, the nanocrystalline materials have been attracting a lot of research interest due to its superior mechanical and electrical properties as compared to the coarse-grained counterpart. For example, the nano-crystalline copper has about 6 times the strength of bulk copper [7]. Furthermore, the improvement in the mechanical properties due to the reduction in grain size has been well-documented. Increase in strength due to the reduction in grain-size is predicted by the Hall-Petch relationship which has also been confirmed numerically by Swygenhoven et al [8] and was first demonstrated experimentally by Weertman [9]. The implantation of nanocrystalline copper as interconnect materials seems to be feasible from the processing viewpoint too. Copper has been used as interconnects materials since 1989 whereas nano-copper has also been widely processed using electroplating and other severe plastic deformation techniques in the past few years. For instance, Lu et al. [10] have reported electroplating of nano-copper with grain size less than 100 nm and electrical conductivity comparable to microcrystalline copper. Furthermore, Aggarwal et al [11] have demonstrated the feasibility of using electrolytic plating processes to deposit nanocrystalline nickel as a back-end wafer compatible process. However, there are certain challenges regarding implantation of nanocrystalline copper as interconnects materials. As discussed above, nanocrystalline copper have a high potential of being used as the next generation interconnect for electronic packaging. However, it is vital to understand their material properties, deformation mechanisms and microstructures stability. Although the increase in strength due to the Hall-Petch relationship which has also been confirmed numerically and experimentally by Weertman [9], the improvement in the fatigue properties is not well documented and no model has been established to predict/characterize these nano materials in interconnection application; conflicting results regarding the fatigue properties have also been reported. Kumar et al [12] reported that for nano-crystalline and ultra-fine crystalline Ni, although there is an increase in tensile stress range and the endurance limit, the crack growth rate also increases. However, Bansal et al. [7] reported that with decreasing grain size, the tensile stress range increases but the crack growth rate decreases substantially at the same cyclic stress intensity range. Thus, nanostructured materials can potentially provide a solution for the reliability of low pitch interconnections. However, the fatigue resistance of nanostructured interconnections needs to be further investigated. Since grain boundaries in polycrystalline material increases the total energy of the system as compare to perfect single crystal, it will resulted in a driving force to reduce the overall grain boundary area by increasing the average grain size. In the case of nanocrystalline materials which have a high volume fraction of grain boundaries, there is a huge driving force for grain to growth and this presented a presents a significant obstacle to the processing and use of nanocrystalline copper for interconnect applications. Millet et al [13] have shown, though a series of systematic molecular dynamics simulations, grain growth in bulk nanocrystalline copper during annealing at constant temperature of 800K can be impeded with dopants segregated in the grain boundaries regions. However, it has been observed that stress can trigger grain growth in nanocrystalline materials [14] and there is no literature available on impeding stress assisted grain growth. There is an impending need to investigate the impediment to grain growth caused by the dopant during fatigue/stress assisted grain growth Dissertation Objectives The goal of present project is to develop a model for the fatigue resistance of nano-materials that have been shown to have superior fatigue resistance. Accordingly, the following research objectives are proposed. Develops a model for predicting fatigue life of nanostructured chip-to-package copper interconnections Develops a fundamental understanding on the fatigue behavior of nanocrystalline copper for interconnect application Addresses the issue on the stability of nanocrystalline materials undergoing cyclic loading Overview of the Thesis The thesis is organized so that past research on nanocrystalline materials forms the basis of the understanding and new knowledge discovered in this research. Chapter 2 reviews much of the pertinent literature regarding nanocrystalline materials, including synthesis, deformation mechanisms, and grain growth. Chapter 3 describes a detailed overview of the technical aspects of the molecular dynamics simulation method including inter-atomic potentials, time integration algorithms, the NVT NPT, and NEPT ensembles, as well as periodic boundary conditions and neighbor lists. Include in this chapter is the algorithms for creating nanocrystalline materials used in this dissertations.. Chapter 4 describes the simulation procedure designed to investigate and develop the long crack growth analysis. The results of the long crack growth analysis will be presented at the end of Chapter 4. Chapter 5 presents the result and discussion on mechanical behavior of single and nanocrystalline copper subjected to monotonic and cyclic loading whereas Chapter 6 presents the result and discussion on the impediment to grain growth caused by the dopant during fatigue/stress assisted grain growth. Finally, conclusions and recommendations for future work are presented in Chapter 5. Chapter 2 This chapter offers an expanded summary of the literature published with regards to the fabrication methods, characterization, and properties of nanocrystalline materials in addition to a description of existing interconnect technology. 2.1 Off-Chip Interconnect Technologies Chip-to-package interconnections in microsystems packages serve as electrical interconnections but they will often failed by mechanisms such as fatigue and creep. Furthermore, driven by the need for increase the system functionality and decrease the feature size, the International Technology Roadmap for Semi-conductors (ITRS) has predicted that interconnections of integrated chip (IC) packages will have a I/O pitch of 90 nm by the year 2018 [2]. The International Technology Roadmap for Semiconductors (ITRS) roadmap is a roadmap that semiconductor industry closely follows closely and its projects the need for several technology generations. The package must be capable of meeting these projections in order for it to be successful. This section reviews some of the current interconnect technology. Wire bonding [15] as shown in Figure 2.1, is generally considered as one of the most simple, cost-effective and flexible interconnect technology. The devices on the silicon die are (gold or aluminum) wire bonded to electrically connect from the chip to the wire bond pads on the periphery. However, the disadvantages of wire bonding are the slow rate, large pitch and long interconnect length and hence this will not be suitable for high I/O application. Instead of wires in the wire bonding, tape automated bonding (TAB) is an interconnect technology using a prefabricated perforated polyimide film, with copper leads between chip and substrate. The advantage of this technology is the high throughput and the high lead count. However, it is limited by the high initial costs for tooling. An alternative to peripheral interconnect technology is the area-array solution, as shown in Figure 2.3, that access the unused area by using the area under the chip. In area-array packaging, the chip has an array of solder bumps that are joined to a substrate. Under-fill is then fills the gap between the chip and substrate to enhance mechanical adhesion. This technology gives the highest packaging density methods and best electrical characteristics of all the avaiable interconnection technology. However, not only is its initial cost is high, it requires a very demanding technology to establish and operate. With the need for higher I/O density, compliant interconnects have been developed to satisfy the mechanical requirements of high performance micron sized interconnects. The basic idea is to reduce shear stress experienced by the interconnects through increasing their height or decreasing of its shear modulus (i.e. increases in their compliant) and hence the name compliant interconnects. Some of recent research in compliant interconnects include Tesseras Wide Area Vertical Expansion, Form Factors Wire on Wafer and Georgia Institute of Technologys Helix interconnects [17-19] as shown in Figure 2.4. Although compliant interconnects can solve the problem of mechanical reliability issue, they are done at the expense of the electrical performance. Since there is a need to reduce the packages parasitic through a decrease line delays, there is a need to minimize the electrical connection length in order to increase the system working frequency. Hence, compliant interconnect may not meet the high electrical frequency requirements of future devices. Figure 2.4: (a) Wide Area Vertical Expansion, (b) Wire on Wafer and (c) G-Helix [17-19] Lead and lead-free solders typically fail mechanical when scaled down to less than to a pitch of 100 mm. Compliant interconnections, on the other hand, do not meet the high frequency electrical requirements. The Microsystems Packaging Research Center at Georgia institute of Technology had demonstrated the feasibility of using re-workable nanostructure interconnections. Aggarwal et al [20] had show that nanostructured nickel interconnections, through a Flip Chip test vehicle, was able to improve the mechanical reliability while maintaining the shortest electrical connection length. However, the main disadvantages of this method was the significant signal loss at high frequency signal of nanocrystalline nickel [21]. As discussed above, nanostructure interconnects technology is the most promising interconnect technology to best meet the stringent mechanical and electrical requirement of next generation devices. However, there is a need of an alternate materials and a sensible choice of materials in this case would be nanocrystalline copper for its high strength material with superior electrical conductivity. Hence, it would be beneficial to use nanocrystalline-copper as material for the nanostructure interconnects. Due to the tendency for the grain to grow, there is a need to stabilize the grain growth in nanocrystalline copper before using it could be considered as a potential candidate for nanostructure interconnect. 2.2 Nanocrystalline material Nanocrystalline materials are polycrystalline materials with an average grain size of less than 100 nm [22]. Over the past decade , new nanocrystalline or nanostructured materials with key microstructural length scales on the order of a few tens of nanometers has been gaining a lot of interest in the material science research society. This is mainly due to its unique and superior properties, as compared to their microcrystalline counterparts which includes increased strength [22] and wear resistance [23]. These unique properties are due to the large volume fraction of atoms at or near the grain boundaries. As a result, these materials have unique properties that are representative of both the grain boundary surface characteristics and the bulk. Recent advances in synthesis and processing methodology for producing nanocrystalline materials such as inert gas condensation [24], mechanical milling [25, 26], electro-deposition [27], and severe plastic deformation [28] have made it possible to produce sufficient nanocrystalline materials for small scale application. 2.2.1 Synthesis Inert gas condensation, the first method used to synthesis bulk nanocrystalline [29], consists of evaporating a metal inside a high-vacuum chamber and then backfilling the chamber with inert gas [30]. These evaporated metal atoms would then collide with the gas atoms, causing them to lose kinetic energy and condenses into powder of small nano-crystals. These powders are then compacted under high pressure and vacuum into nearly fully dense nanocrystalline solids. The grain size distribution obtained from this method is usually very narrow. However, the major draws back of this method are its high porosity levels and imperfection bonding. Grain coarsening also occurs due to the high temperature during the compaction stage [31]. Mechanical milling consists of heavy cyclic deformation in powders until the final composition of the powders corresponds to a certain percentages of the respective initial constituents [25, 26]. A wide grain size distribution is obtained by this method. This technique is a popular method to prepare nanocrystalline materials because of its applicability to any material and simplicity. However, their main drawback includes contamination and grain coarsening during the consolidation stage. Electro-deposition consists of using electrical current to reduce cations of a desired material from a electrolyte solution and coating a conductive object on the substrate. Electro-deposition has many advantages over processing techniques and this includes its applicability to a wide variety of materials, low initial capital investment requirements and porosity-free finished products without a need for consolidation processing [27]. Furthermore, Shen et al. [32] and Lu et al.[33] had recently show that the right electro-deposition condition can produce a highly twinned structure which leads to enhanced ductility. The main drawback of this method is it is the difficulty to achieve high purity. Severe plastic deformation, such as high-pressure torsion, equal channel angular extrusion (ECAE), continuous confined shear straining and accumulative roll-bonding, uses extreme plastic straining to produce nanocrystalline materials by mechanisms such as grain fragmentation, dynamic recovery, and geometric re-crystallization [34]. It is the only technology that transformed conventional macro-grained metals directly into nanocrystalline materials without the need of potentially hazardous nano-sized powders. This is achieved by introducing very high shear deformations into the material under superimposed hydrostatic pressure. Two of the most commonly used methods are high-pressure torsion and ECAE [35]. In the study of the effect of ECAE on the microstructure of nanocrystalline copper, Dalla Torre et al [36] observed that the grains become more equi-axial and randomly orientation as the number of passes increases, as shown in Figure 2.5 Figure 2.5: Microstructure of ECAE copper subjected to (a) 1 passes (b) 2 passes (c) 4 passes (d) 8 passes (e) 12 passes and (f) 16 passes [36] 2.2.2 Mechanical Behavior of nanocrystalline materials Due to the small grain size and high volume fraction of grain boundaries, nanocrystalline materials exhibit significantly different properties and behavior as compared to their microcrystalline counterpart. The structure and mechanical behavior of nanocrystalline materials has been the subject of a lot of researchers interests both experimentally [37-43] and theoretically [44-50]. This section reviews the principal mechanical properties and behavior of nanocrystalline materials. 2.2.2.1 Strength and ductility Recent studies of nanocrystalline metals have shown that there is a five to ten fold increases in the strength and hardness as compared to their microcrystalline state [7, 36, 37, 51, 52]. This increase in the strength is due to the presence of grain boundaries impeding the nucleation and movement of dislocations. Since decreasing grain boundary size increases the number of barrier and the amount of applied stress necessary to move a dislocation across a grain boundary, this resulted in a much higher yield strength. The inverse relationship between grain size and strength is characterized by the Hall-Petch relationship [53, 54] as shown in equation (2.1). Eq (2.1) In equation (2.1), s is the mechanical strength, k is a material constant and d is the average grain size. Hence, nanocrystalline materials are expected to exhibit higher strength as compared to their microcrystalline counterpart. Figure 2.6 and Figure 2.7 show the summary of hardness and yield strength from tensile test that are reported in the literature. Indeed, hardness and yield strength of copper with a grain size of 10nm (3GPa) can be one order higher than their microcrystalline counterpart. To the larger specimens. Derivation from Hall-Petch relationship begins as the grain size approaches 30nm where the stresses needed to activate the dislocation multiplication via Frank-Read sources within the grains are too high and the plastic deformation is instead accommodated by grain boundaries sliding and migration.[12]. Furthermore, as the grain size reduces, the volume fraction of the grain boundaries and the triple points increases. Material properties will be more representative of the grain boundary activity [64] and this will resulting the strength to be inversely proportional to grain size instead of square roots of the grain size as predicted by Hall Petch relation [65]. Further reduction in the grain size will result in grain boundaries processes controlling the plastic deformation and reverse Hall-Petch effect, where the materials soften, will take place. Although sample defects had been account for the earlier experimental observation of reverse Hall-Petch effect[24], Swygenhoven et al [66] and Schiotz et al [47], using molecular simulation, was able to showed that nanocrystalline copper had the highest strength (about 2.3GPa ) at a grain size of 8nm and 10-15nm respectively. Conrad et al [67] pointed out that below this critical grain size, the mechanisms shifted to grain boundary-mediated from dislocation-mediated plasticity and this causes the material to become dependent on strain rate, temperature, Taylor orientation factor and presence of the type of dislocation. The yield stress of nanocrystalline copper was highly sensitive to strain rate even though it is a fcc materials. The strain rate sensitivity, m, in equation 2.2 a engineering parameter which measured the dependency of the strain rate and Figure 2.8 shows a summary of m as a function of grain size for copper specimen in the literature [51, 68-70]. Due to high localized dislocation activities at the grain boundaries which results in enhanced strain rate sensitivities in nanocrystalline materials, m increases drastically when the grain size is below 0.1 mm as shown in Figure 2.8. (2.2) Room temperature strain rate sensitivity was found to dependent on dislocation activities and grain boundaries diffusion [52, 71, 72]. Due to the negligible lattice diffusion at room temperature, the rate limiting process for microcrystalline copper was the gliding dislocation to cutting through forest dislocation, resulting in low strain rate sensitivities. However, due to the increasing presence of obstacles such as grain boundaries for nanocrystalline materials, the rate limiting process for smaller grain size was the interaction of dislocation and the grain boundaries, which is strain rate and temperature dependence. By considering the length scale of the dislocation and grain boundaries interaction, Cheng et al [52] proposed the following model for strain rate sensitivities . (2.3) z is the distance swept by the dislocation during activation, r is the dislocation density and a, a and b are the proportional factors. With this model, they will be able to predict higher strain rate sensitivities for nanocrystalline material produced by severe plastic deformation as compared to other technique. Since the twin boundaries in nanocrystalline or ultra fine grain copper served as a barriers for dislocation motion and nucleation which led to highly localized dislocations near the twin boundaries, the strain rate sensitivity of copper with high density of coherent twin boundaries was found to be higher than those without any twin boundaries [33]. Lastly, the increase enhanced strain rate sensitivity in nanocrystalline copper had been credited for it increases in strength and ductility. For example, Valiev et al [60] credited the enhanced strain rate sensitivity of 0.16 for the high ductility. In addition to a strong dependency on the strain rate, strength in nanocrystalline materials was also highly dependent on the temperature. Wang et al [73] observed that the yield strength for ultra fine grain copper with a grain size of 300nm increases from approximately 370MPa to 500MPa when the temperature reduces from room temperature to 77k. The authors attributed this increase in yield strength due to the absence of additional thermal deformation processes at 77k. This is consistent with Huang et al [74] observation where the temperature dependence of nanocrystalline copper with an increase in hardness of nanocrystalline copper with lowering the temperature is noted Ductility is another important characteristic of nanocrystalline materials. In microcrystalline materials, a reduction in grain size will increase the ductility due to the presence of grain boundaries acting as effective barriers to the propagation of micro-cracks[75]. However, nanocrystalline copper showed a lower strain to failure than that of their microcrystalline counterparts and this lacks in ductility was attributed to the presence of processing defects [76]. Recent advanced in processing of nanocrystalline materials offer materials with fairly good ductility in additional to ultra-high strength. Lu et al [10] reported that nanocrystalline copper with minimal flaw produced via electro-deposition had an elongation to fracture of 30%. Furthermore, Youssef et al [77] observed a 15.5% elongation to failure for defect free nanocrystalline copper produced via mechanical milling. Hence, it was possible for nanocrystalline copper to be both strong and ductile if the processing artifacts are minimized. The failure are usually consists of dimples several time larger than their grain size was normally found on the failure morphology of nanocrystalline materials and Kumar et al [78] presented the following model for initiation and hence the eventual failure of nanocrystalline materials. Furthermore, the presence of shear region was found to be due to shear localization since the ratio of strain hardening rate to prevailing stress was usually small [79, 80]. Figure 2.9: Schematic illustration of fracture in nanocrystalline material postulated by Kumar et al [78] 2.2.2.2 Creeps Nanocrystalline materials are expected to creep during room temperature. This is because Due to the higher fraction of grain boundaries and triple junctions, self diffusivity of nanocrystalline material had been shown to increase by an order of three as compared to microcrystalline copper [81]. Since creep behavior was dependent on grain size and diffusivity, with creep rate increases with an increase in diffusivity or a decrease in grain size, the creep temperature for nanocrystalline copper was known to be a small fraction of melting temperature (about 0.22 of its melting points). Furthermore, since creep had always been cited as one of the reason for grain size softening in nanocrystalline materials, creeps were other important mechanical properties of nanocrystalline materials that had been gaining a lot of researchers attention. Due to the high volume fraction of grain boundaries and enhanced diffusivity rate

pay equity :: essays research papers

The American Association of University Women (AAUW) has long fought to end wage discrimination. Despite the Equal Pay Act and many improvements in women’s economic status over the past 40 years, wage discrimination still persists. AAUW continues to believe that pay equity—economic equity—is a simple matter of justice and strongly supports initiatives that seek to close the persistent and sizable wage gaps between men and women. The effects of pay inequity reach far. According to a 1999 study by the Institute for Women’s Policy Research and the AFL-CIO, based on U.S. Census Bureau and Bureau of Labor statistics, women who work full time earn just 74 cents for every dollar men earn. That equals $148 less each week, or $7,696 a year. Women of color who work full time are paid even less, only 64 cents for every dollar men earn—$210 less per week and $11,440 less per year. With a record 64 million women in the workforce, pay discrimination hurts the majority of American families. Families lose $200 billion in income annually to the wage gap—an average loss of more than $4,000 for each working family. In addition, wage discrimination lowers total lifetime earnings, thereby reducing women’s benefits from Social Security and pension plans. Wage inequalities are not a result of women’s qualifications or choices. Wage discrimination persists despite women’s increased educational attainment, greater level of experience in workforce, and decreased amount of time spent out of the workforce raising children. †¢Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Education. Although the number of women attaining baccalaureate and advanced degrees now surpasses the number of men, in 1999 the median wages of female college graduates were $14,665 less than those of male graduates. College-educated African American women earn only $1,500 more than white male high school graduates. †¢Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Experience. Women gain only approximately 30 cents per hour for five additional years of work experience, compared to $1. pay equity :: essays research papers The American Association of University Women (AAUW) has long fought to end wage discrimination. Despite the Equal Pay Act and many improvements in women’s economic status over the past 40 years, wage discrimination still persists. AAUW continues to believe that pay equity—economic equity—is a simple matter of justice and strongly supports initiatives that seek to close the persistent and sizable wage gaps between men and women. The effects of pay inequity reach far. According to a 1999 study by the Institute for Women’s Policy Research and the AFL-CIO, based on U.S. Census Bureau and Bureau of Labor statistics, women who work full time earn just 74 cents for every dollar men earn. That equals $148 less each week, or $7,696 a year. Women of color who work full time are paid even less, only 64 cents for every dollar men earn—$210 less per week and $11,440 less per year. With a record 64 million women in the workforce, pay discrimination hurts the majority of American families. Families lose $200 billion in income annually to the wage gap—an average loss of more than $4,000 for each working family. In addition, wage discrimination lowers total lifetime earnings, thereby reducing women’s benefits from Social Security and pension plans. Wage inequalities are not a result of women’s qualifications or choices. Wage discrimination persists despite women’s increased educational attainment, greater level of experience in workforce, and decreased amount of time spent out of the workforce raising children. †¢Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Education. Although the number of women attaining baccalaureate and advanced degrees now surpasses the number of men, in 1999 the median wages of female college graduates were $14,665 less than those of male graduates. College-educated African American women earn only $1,500 more than white male high school graduates. †¢Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Experience. Women gain only approximately 30 cents per hour for five additional years of work experience, compared to $1.

Gas Agency

Software requirement specification for BuzzyBUY. com (Online Shopping and auctioning Web Site) Prepared by Table of Contents 1. Introduction 2 1. Purpose 2 2. Document Conventions2 3. Intended Audience and Reading Suggestions2 4. Product Scope2 5. References 2 2. Overall Description 3 1. Product Perspective3 2. Product Functions3 3. User Classes and Characteristics 3 1. Administrators 3 2. Buyers4 3. Sellers 4 4. Casual visitors4 4. Design and Implementation Constraints5 . User Documentation6 6. Assumptions and Dependencies6 3. External Interface Requirements6 1. User Interfaces6 2. Hardware Interfaces6 3. Software Interfaces6 4. Communication Interfaces7 4. System Features7 1. Listing7 2. Account Creation8 3. Selling8 4. Buying8 5. Rating8 6. Others8 5. Other Non Functional Requirements9 1. Performance Requirements9 2. Safety Requirements9 3. Software Quality Attributes 9 4. Business Rules9 6. Appendix A: Glossary9 7. Appendix B: Analysis Models10 1. Introduction: 1. Purpose: The p urpose of this SRS is to specify the requirements of the web based software application buzzybuy. om, which is an online shopping and bidding system. The module to be developed is the first version of buzzybuy –version 1. 0. This Software Requirements Specification provides a complete description of all the functions and specifications of buzzybuy –version 1. 0 2. Document conventions: IEEE standards used. Proper sub numbering system for sub topics based on the importance and priority of the matter. 3. Intended audience and reading suggestions:The expected audience of this document is the faculty in charge of software engineering lab for 6th semester Computer Science, NITK suratkal .It will be used as a reference for grading in the lab for even semester of 2006. There is no suggested reading to be done before going through the document. 4. Product scope: Buzzybuy. com is designed to run on both any modern platform with GUI. It is assumed that the back end that will be used for implementation is MySQL and the front end that will be used is PHP. 5. References: 1. The applicable IEEE standards are published in â€Å"IEEE standards collection†, 2001 edition. 2. Software Engineering, A Practitioner’s approach, 6th edition. By Roger S Pressman. McGraw hill international. 2. Overall description 1.Product perspective:This is proposed to be an enhanced model of the present day existing shopping and auctioning portals. Many flaws in the present online shopping portals haven’t been able to exploit the full potential of e-commerce market. The Software Requirements Specifications intends to identify the flaws in the current existing system and propose an alternative or a solution to them. 2. Product Functions: †¢ It consists of two modules 1. Customer module 2. Administrator module †¢ A customer should have a user account for carrying out transactions. †¢ Transactions include buying, selling and auctioning. Administrator pr ovides the customer with an account following proper registration procedures to prevent malpractices in the transactions. †¢ Any visitor is allowed to browse through the product list, their prices and bidding procedures. †¢ Buying, selling and bidding procedures are kept transparent so that any user is able to go through the procedures. 3. User classes and characteristicsThere are 3 kinds of users for the proposed system 1. Administrators: They create user accounts and give it to the required customers. ? To educate consumers about Buzzybuy’s range of products and indigenous services. They must provide rules for the transactions. ? They must maintain the website and update the same making necessary changes at times. ? They must take care of the security issues involved in the transactions. ? They must inform the users about their transaction status and keep them updated about the progress through emails. ? They must receive feedbacks from their customers or any user s about their system and act upon the relevant ones. ? Look up at all the legal issues involved with the business. ? Keep place for advertisements in the website as a revenue generating option.The place has to be maintained and proper listings done. ? Any failures in the system have to be detected and repaired. 2. Buyers: They are the genuine customers of the website. They can see the listing, bid for various things, and also buy them to various payment options. 3. Sellers: These are the people involved in selling their products through buzzybuy. They consider this as a virtual market place. They need to be provided with proper advertisement place, and ratings of customers. The sellers too are rated based on the feedback they get from previous transactions completed from customers.These feedback data are treated with great respect and are transparent to everyone. The sellers too value this very highly. 4. Casual visitors: These people don’t come to the site on specific intens ions of buying or selling. They just visit to see the listing and too see the products. They need not have an user account. They can be future potential customers. They sellers can lure them with advertisements on the site based on their budget. The following usecase diagram states the above data in a graphical form: [pic] Fig 1 Usecase Diagram for BuzzyBuy 4. Design and Implementation Constraints The main constraint here would be the checking the genuineness of the buyer, which is not always possible. There can be security risks involved. †¢ The design constraints are that the browser at each place may not follow similar screen resolutions, browsers etc. This can lead to the website not having the impact it is planned to have. †¢ Also the rules of the land will prohibit certain items to be sold on the site. Hence all those factors need to be filtered in. †¢ Also storage space constraints may come if the listing becomes too large. Hence a strong server needs to be cho sen to host the database. 5.User Documentation: 1. Online user help with all the necessary help needed to use the site in a bulletin format. 2. Problem addressable forms 3. Software and database specification 4. Details of rules and regulation to sellers as well as buyers. 6. Assumptions and Dependencies None as per now 3. External Interface Requirements: 1. User Interfaces: Each part of the user interface intends to be as user friendly as possible. The fonts and buttons used will be intended to be very fast and easy to load on web pages. The pages will be kept light in space so that it won’t take a long time for the page to load.The staring page will ask the user what kind of a user is he, either seller, buyer or a casual visitor. Based on which the future pages will be loaded in a sequential manner. Each listing page will have a area to put the bid, the product details with photo etc. Each page also will have a search engine to search the products available so that it is re adily available and the user need not search for it. Each button will have an online help link to help the user in understanding the process. 2. Hardware Interfaces: A web server will be used to host the WebPages and the database management system.Most pages will be dynamic pages built with php. Each page will be optimized to the type of web browser and resolution being used. A minimum of PIII system running at 733 MHz will be needed to run the modules. Normal modes of network modes used in Internet technology will be used. 3. Software Interfaces: The incoming message mostly includes requests for a specific task, which on the course of the development will be decided in detail and dealt with in design specification document. The incoming messages from the messages will be converted to a specific format in the database language, the processing made and the request served.The operations will be intended to be made as fast as possible. 4. Communications Interfaces: The web server maint enance and other activities to be done using FTP transfer protocol. The security and other issues will be dealt with in the course of the project, as there is little idea as to how these things work to our team as per now. There will other communication interfaces with the users of the site with site-specific email, forms and complaint addressable mechanisms. These things as far as possible will be automated. 4. System Features 1.Listing: This includes the listing feature of the website where any search or other request of a user to a particular subject is served. The pertinent web pages are loaded and the particular database is initialized. There are listings based on the priority as by user preferences. This is actually the listing of web pages to the users by time of selling, deadline, price, quality etc. Listing includes listing of o Products to be sold directly o Products open for bidding till a particular date o Sellers in a particular area or with specific ratings o Used prod ucts on for sale. Just casual listings of random things o Payment options to buy or sell. |Action |Software reaction | |User logs in the system |The system authenticates | |User defines the information to view |System provides the necessary details as requested by the | | |particular employee | |User views the information | |Table No 1. The table states a typical control passing in the system during logging in Listings will be made very fast and user friendly. Proper security is also a very pertinent point here. 2. Account creation: This includes creating user accounts to each of sellers and buyers separately. This includes taking pertinent information from them and then initializing the database. The database needs to be properly updated on each transaction by the user and all the details of his/her account should figure in the account listing.The security of the account also should be dealt with. 3. Selling:Here the seller can list his/her things on his /her quoted price. Or else he can keep it for a bidding process where he is not sure of the price. The details of which will be kept in the user database. The details of his goods on selling list will be updated to him on a regular basis to his email id. The process of selling can include some bargaining too, but the details are yet to be thought of.The payment and feed back details are kept transparent. 4. Buying:There are 4 ways of buying or intending to buy o Direct buying o Bidding o Group buying o Tracking The details of which will be dealt with in the design specification. Each of these details are kept in the user account where he is kept updated about all his moves. 5. Ratings: Each products, buyers and sellers are constantly rated based on the feedback and the market behavior so that users feel secure about the system.These ratings are given based on a best pointer of five, the details of which are yet to be worked out. These ratings are intended to bring some trust and credibility to the concept of an online market. 6. Others: Include money transactions, legal issues, regional tastes, costs involved, business models used etc pertinent issues but won’t be seen in detail in the document as the things are beyond the reach of the design team. 5. Other Nonfunctional Requirements: 1. Performance Requirements: As stated before. 2.Safety Requirements: Suitable safety has to be taken while allowing a product to be sold on buzzybuy. They have to follow the legalities of the land, and must be ethical. There could be possible misuse of the system by bogus user, bidding and buying without paying up. It is not always possible to check the postal addresses. Also during money transactions the unreliable networks may cause further problems. So such practices need to be avoided. 3. Software Quality Attribute: The system is easy to load and light .It adds to the quality and usability of the system. Some others quality considerations such as adaptability, availability, correctness, flexib ility, interoperability, maintainability, portability, reliability, reusability, robustness, testability, and usability will also be very seriously taken to consideration. 4. Business Rules: Nothing is above customer satisfaction. So the rules need to be kept flexible to meet user needs and preferences at different times. Other models can be applied but is beyond the scope of the team. . Appendix A: Glossary 1. SRS: Software requirement specification 2. GUI: Graphical user interface. 3. PHP: Personal home pages 4. IEEE: Institute of electrical and electronic engineers. 5. FTP: File transfer protocol 6. SQL: Structural query language. 7. Appendix B: Analysis Models [pic] ———————– Central Processing server Listing Selling Buying Administration Administrator Casual visitor Seller Buyer Buyer Seller Casual visitor Administrator Administration Buying Selling Listing Central Processing server

Roman Republic History and Facts Essays

Roman Republic History and Facts Essays Roman Republic History and Facts Essay Roman Republic History and Facts Essay Essay Topic: The Republic Rome According to legend, the city of Rome was founded by two twin brothers Romulus and Remus. They were kidnapped when they were still babies and left near the Tiber River. The wolves cared for them but when they grew up, they found a shepherd and the shepherd also cared for them. They founded the city of Rome but they quarreled with the leader of it but some historians say that the name of the city has been theirs. Romulus won and named him the city of Rome. History of Rome Rome was governed by kings, but after only seven of them had ruled, the Romans took power over their own city and ruled themselves. They then instead had a council known as the senate which ruled over them. From this point on one speaks of the Roman Republic. The word Republic itself comes from the Latin (the language of the Romans) words res publica which mean public matters or matters of state. The senate under the kings had only been there to advise the king. Now the Senate appointed a consul, who ruled Rome like a king, but only for one year. This was a wise idea, as like that, the consul ruled carefully and not as a tyrant, for he knew that otherwise he could be punished by the next consul, once his year was up. | Rome knew four classes of people. This division was very important to the Romans. The lowest class were the slaves. They were owned by other people. They had no rights at all. The next class were the plebeians. They were free people. But they had little say at all. The second highest class were the equestrians (sometimes they are called the knights). Their name means the riders, as they were given a horse to ride if they were called to fight for Rome. To be an equestrian you had to be rich. The highest class were the nobles of Rome. They were called patricians. All the real power in Rome lay with them. The Roman Republic was a very successful government. It lasted from 510 BC until 23 BC almost 500 years. In comparison the United States of America, it only exists since 1776 less than 250 years. Ancient Roman Gods 12 Greek Olympians| 12 Roman Olympians| Hera Queen of heaven (Zeuss wife) and goddess of marriage| Juno goddess of Marriage| Zeus King of gods/heaven| Jupiter A. K. A Jove The King of the gods and the god of the sky| Hades god of underworld| Pluto – god of the dead| Poseidon god of sea| Neptune god of the Sea| Hestia goddess of hearth/domesticity| Vesta goddess of the Hearth, the Home and the Roman state| Ares god of war| Mars god of War| Hephaestus Blacksmith of gods| Vulcan god of Fire, the Forge and Blacksmiths| Apollo god of music| Apollo god of the sun, music, medicine and healing, archery and prophecy| Hermes Patron of thieves and merchants/traders, messenger of Zeus| Mercury Messenger of the gods and Finance. goddess of moon| Diana goddess of Hunting| Aphrodite goddess of love and beauty| Venus goddess of Love and Beauty| Athena goddess of wisdom, justice, crafts, and war| Minerva goddess of Wisdom|

7 Questions for the New Year Bringing You into Alignment with your Work

7 Questions for the New Year Bringing You into Alignment with your Work Last night I went to a Rosh Hashanah service at Beyt Tikkun in Berkeley, California, where one of the most valuable offerings of the evening was a handout entitled â€Å"High Holiday Workbook.† The workbook encourages participants to reflect on where in our lives we might have some spiritual alignment work to do. It asks questions about our relationships with other human beings, with our body and soul, and, most appropriately to my profession, with our work. How spiritually nourishing is your work? The High Holiday Workbook poses many great questions about what’s happening in the area of work. Following are some of them. I invite you to consider these questions, regardless of whether you are currently employed or looking for work as your full-time occupation: What have been the problems you’ve faced? Have you had good relationships with co-workers? Have you felt fulfilled? Have you been involved in collective efforts to change the workplace †¦ or have you felt powerless and unable to envision changing anything? If you are/were in a supervisory position, do/did you treat your supervisees with the respect that they deserve? Did you discharge anger from work [or from unemployment] by punishing yourself (e.g. through alcohol or drugs) or by dumping on friends or lovers – or did you express that anger at the appropriate targets or through collective action? How healthy were your coping mechanisms for stress? These questions encourage us to look inward and to consider doing things a different way if we find places where we are not being our spiritually highest selves. Once we answer the questions, the next step is to identify what we can contribute to transform any problems. Partnering for Support and Success As with many calls to examine our own thoughts and behavior, it is often difficult to do accomplish our goals alone. We might recognize that something needs to be done, but not do it. And so the workbook goes a step further, suggesting that we find a partner to check in with daily between now and Yom Kippur about how we are progressing on our list. This partner is ideally someone who has no personal stake in what you do or do not accomplish, and who will encourage you to think through your options without offering any pointed advice. Whatever your religious faith, now might be a good time to take on an important area of your life, or several areas, including work, health, and/or relationships. If you transform even one small area, it will have an impact on your own peacefulness and alignment, as well as on the people and communities that surround you. L’shanah tovah. Wishing you a good year full of sweetness, joy and transformation.

Persuasive Essay Essays - Roswell UFO Incident, Free Essays

Persuasive Essay Essays - Roswell UFO Incident, Free Essays Persuasive Essay December 16, 1997 U.F.O., extra terrestrials and aliens do they really exist? Is there a government conspiracy? Why can so many people swear to have been abducted or seen flying saucers and all describe the same thing and be wrong? For many years people have been fascinated with creatures from other planets. Many shows and movies have these types of subjects, such as, ""X-Files,"Men In Black," "Independce Day," "Star Wars," and a classic , "E.T." There have been many sightings, for example, the Roswell incident, over 50 years ago. Little men with a round, bald head, beatty eyes, 3 feet tall, that hover 2 feet above the ground, is the most commonly described alien. Can there really be other beings capable of reaching the planet earth? Many people would say "There are no such things," like Cory stated, because of some insignificant reasons. For example, there is no type of fuel on this planet or is known by humans to have the capabilities of taking something from one galaxy to another, but aliens are not on from the earth and where they come from such a fuel may be readily available for them to use. Many others like to say that U.F.O.s have not been pictured or documented, or that really people are say it is just mearly swamp gas, or possibly a weather balloon. The claims of sightings comes from ordinary people and are in perfect mental health. Mrs. Engler, one of my friends mother, believes she saw a U.F.O. one night, and when she told her husband what she saw, he thought she was crazy. The next morning, however his mind changed when he saw a pictured of what Mrs. Engler was describing. Another excuse some people like to say is that these sight ings are mearly just hoaxes to occupy the minds of the citizens set up by the government to coverup some other kind of scandal. Realistically, it would be nearly impossible to pull of these kind of stunts for so many years and never get caught. On July 3, 1947, rancher W.W. "Mac" Brazel came across the wreckage of a crashed craft on one of his sheep pastures.(2) He showed the strange debris to some neighbors, then alerted the sheriff in Roswell. Over the next few days, the U.S. Army Air Force cleared away the wreckage, and on July 8 issued a press release identifying it as a crashed flying saucer. The next day, the government said it had been mistaken; it was actually a crashed weather balloon. This summer, Roswell marks the anniversary of the crash and 50 years of mystery, investigations, government secrecy, conspiracy theories and allegations of cover-ups.(1)

Matteo Ricci and China Research Paper Example | Topics and Well Written Essays - 1000 words

Matteo Ricci and China - Research Paper Example 1-50).1 The aim of this research paper is to discuss Matteo Ricci in China, why he came to China, what he completed during his stay in China, as well as the impacts he had on Chinese society during that time and in the modern day. Why Matteo Ricci came to China The main reason why Matteo Ricci went to China encompasses the desire to spread the Christian gospel to China. As an intelligent and talented Jesuit, Ricci sought to preach the Christian message in China. He entered China during the Ming dynasty (1368-1644), marking the beginning of what can be referred as the third period of the history of Christianity in China. Together with other Jesuits, Ricci intended to see the implementation of the insights of Alessandro Valignano, their Jesuit chief. In order to make China a Christian society, he made attempts to connect with both the ordinary people and the educated Chinese. The Christian doctrines that Ricci wanted to spread in China mainly included those of Catholicism (Fontana 2011 , p. 1-50).1 Ricci also came to China with the aim of amassing knowledge, which he could disseminate to people in other parts of the world. Of utmost importance was his desire to spread Christianity to the Chinese cultures, which had no prior knowledge of Christianity but used to be strict followers of other religious beliefs. Thus, his determination to see Christianity spread in China can be termed as the main reason why Matteo Ricci came to China (Brockey 22007, p. 10-250). What Matteo Ricci completed during his stay in China and his impact during that time up to modern day China Some of the accomplishments that Ricci made in China included preaching and spreading Christianity to most of the parts of China. His main focus included spreading Catholicism doctrine, teaching astronomy, geography, and mathematics. During his stay in China, Ricci collected maps of China and merged them with maps of the west to come up with the map of the entire world (Brockey 2007, p. 10-250).2 For the first time, there came to be the Chinese Global map, which Ricci himself compiled. His other contributions included the introduction of geographic coordinate system, as well as western geography. The coordinate system helped in the measuring of longitude and latitude in maps, which led to China. Ricci introduced western civilization to the Chinese people; this civilization spread to other countries around China such as Japan (Hsia 2010, p. 30-120).3 His other accomplishments while in China included doing twenty writings in Chinese. These writings encompassed scientific works, religious writings, as well as treaties; one of the most famous writings that he did was the â€Å"True Doctrine of God.† Moreover, he contributed to the compiling of the first European-Chinese dictionary and two Portuguese-Chinese dictionaries. Ricci’s accomplishments in China also encompassed leaving behind 2,500 Chinese Catholics at the time of his death; most of them included the educated ones . His legacy also encompassed a Friendship Treatise, Mnemonic arts treatise, as well as a translation of Elements of Geometry in Chinese (Lehner 2011, p. 4-70).3 Ricci’s accomplishments while in China also encompass writings that entailed catechisms and the translation of Chinese prayers. Moreover, Ricci was highly involved in the composition of hymns in the Chinese language, which played a crucial role in his efforts to spread the doctrines and teachings of