Página 11 dos resultados de 3096 itens digitais encontrados em 0.071 segundos

‣ MEMS-based resonant sensor arrays : selective detection of volatile and toxic chemicals; Microelectromechanical systems-based resonant sensor arrays : selective detection of volatile and toxic chemicals

Whitfield, George C., 1981-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 59 leaves; 3738430 bytes; 3743743 bytes; application/pdf; application/pdf
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With growing concerns about homeland security, public health, and environmental cleanliness, there is a strong need today for robust chemical sensing systems that are portable in addition to being highly sensitive. While there are many options available for gaseous chemical detection and identification, not all are well-suited toward the creation of a portable device. Boston MicroSystems, Inc. (BMS) has developed a resonant chemical sensor that is predicted to meet the performance needs of the current market in terms of gas sensitivity, operational reliability, and overall device portability. Desirable device characteristics are attained through integrating aluminum nitride and silicon carbide in processes that are protected through a strong base of intellectual property. By developing a standardized platform for gas detection based on this sensor technology, barriers to entering the targeted markets may be overcome.; by George C. Whitfield.; Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 2004.; Includes bibliographical references (leaves 58-59).

‣ Formation and processing of rheocast microstructures

Martínez-Ayers, Raúl Andrés, 1977-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 125 leaves; 5939357 bytes; 5955125 bytes; application/pdf; application/pdf
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(cont.) given slurry was proposed. The fluidity of rheocast A357 alloy slurries was contrasted with the fluidity of superheated liquid. Rheocast slurries with 37% solid particles,were found to flow about half as far as fully liquid alloy superheated 20⁰C above the liquidus.; The importance of semi-solid metal processing derives primarily from its ability to form high integrity parts from lightweight alloys. Since the discovery of the semi-solid metal microstructure, most part production was by reheating of billets which possessed a suitable microstructure ("thixocasting"). However, it is now apparent that there are significant advantages of forming semi-solid slurry directly from liquid alloy ("rheocasting") and efficient rheocasting processes have been engineered. In this work, experimental and analytical approaches were taken to study how non-dendritic microstructures form and evolve in Al-4.5wt%Cu alloy during the earliest stages of solidification. Experimental results showed that particles in quenched rheocast alloy were already spheroidal, and free of entrapped eutectic, after 5 seconds of solidification time. Spheroidal particles were also formed by reheating equiaxed dendrites of approximately 10 [micro]m radius above the eutectic temperature for 5 seconds...

‣ Fabrication and characterization of nanostructures from self-assembled block copolymers

Cheng, Joy, 1974-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 109 p.; 11638378 bytes; 19891122 bytes; application/pdf; application/pdf
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Nanoscale magnetic dot arrays have attracted considerable interest, both for fundamental studies of micromagnetism and for possible applications in high-density magnetic data storage. Self-assembled block copolymers provide an alternative nanolithography technique to fabricate large-area nanomagnet arrays. Block copolymer thin films that micro-phase separate into periodic domains can be used as templates to define arrays of close-packed nanostructure, using a series of etching steps. Using polystyrene-polyferrocenyldimethyl-silane (PS-PFS), large-area polymer dots, silica dots and magnetic dots with periods of 56 nm were made using a series of plasma etching steps. Magnetometry techniques are used to characterize the bulk magnetic behavior of the dot arrays of Co, NiFe and pseudo spin valve structures. These dot arrays show strong magnetostatic interaction between the dots and within the dots. The self-assembly process is simple and low cost, however, the block copolymers typically have uncontrolled defects and lack long-range order. A topographically patterned substrate is used to guide the phase-separation in a subsequently deposited block copolymer film. The lateral dimensions of the patterns in the substrates, and interfacial interactions...

‣ Fabrication and characterization of wafer-level gold thermocompression bonding

Tsau, Christine H. (Christine Hsin-Hwa), 1976-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 140 p.; 11630327 bytes; 11630133 bytes; application/pdf; application/pdf
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Packaging is an important aspect of microelectromechanical systems (MEMS) design. As MEMS devices traverse multiple energy domains, sometimes operating in hostile conditions, the need to maintain reliability and functionality makes packaging a challenging problem. Often, the package needs to be specially designed for each device. Given the typically low volume productions, the packaging cost can often exceed the device cost. One way to lower that cost is to package at the wafer-level. This thesis explores a low temperature wafer bonding technique: thermocompression bonding. This technique relies on the applied pressure and temperature to forge a bond. The pressure brings two surfaces into close proximity while the temperature reduces the pressure requirement to deform the surface asperities. In this work, gold thin film was used to bond two silicon substrates. The thesis discusses the fabrication process, its associated challenges, and provides guidelines to achievesuccessful bonding. Characterization of the process focused mainly on the effects of bonding temperature (260 to 300° C), pressure (1.25 to 120 MPa) and time (2 to 90 min). The resultant bond was quantified using a four-point bend-delamination technique. High bond toughness was obtained and the bond quality was found to improve with increases in the bond temperature and pressure. However...

‣ The electromigration drift velocity and the reliability of dual-damascene copper interconnect trees

Wei, Frank L. (Frank Lili), 1977-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 98 p.; 3325265 bytes; 3325072 bytes; application/pdf; application/pdf
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Cu has replaced Al as the interconnect metal of choice for high performance Si-based integrated circuits. Its electromigration behavior must be quantified and an experimental basis for a circuit-level reliability assessment is needed. Experiments on straight two-terminal via-to-via Cu dual-damascene segments with different line lengths, both with via-above and via-below geometries, have been carried out. By contrasting the failure characteristics of via-above and via-below structures, the Cu/Si3N4 interface has been identified as the site for void nucleation and the most dominant diffusion path. Consequently, an asymmetry in lifetime exists between via-above and via-below interconnect lines. It has also been found that at short line lengths, true Blech immortality occurs only for very short lines, at best, due to the ease of void nucleation. Immortality due to void growth saturation is also limited, because, in the absence of the conducting refractory-metal current-shunting overlayers characteristic of Al technology, very small voids at vias can cause failures. We find that at long lengths a sub-population of Cu lines is immortal. We propose that this is a result of non-blocking liners at the base of the vias associated with the high stresses developed at the ends of the lines. In order to quantify the fundamental Cu electromigration kinetics which precedes all failure modes...

‣ Synthesis and electrochemical characterization of lithium vanadium phosphate

Hsiung, Chwan Hai H. (Chwan Hai Harold), 1982-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 41 leaves; 2494839 bytes; 2493201 bytes; application/pdf; application/pdf
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In a world where the miniaturization and the portability of electronic devices is king, batteries play an ever-increasingly important role. They are vital components in many consumer electronics such as cell phones and PDAs, in medical devices, and in novel applications, such as unmanned vehicles and hybrids. As the power demands of these devices increases, battery performance must improve accordingly. This thesis is an introductory investigation into the electrochemical properties of a promising new battery cathode material: lithium vanadium phosphate (Li3V2(PO4)3) (LVP). Studies of other members of the phospho-olivine family, which LVP is a part of, indicate that the olivines have high lithium diffusivity but low electronic conductivity. LVP is part of the phosphor- olivine family, which traditionally has been shown to have high lithium diffusivity but low electronic conductivity. LVP was synthesized via a solid-state reaction and cast into composite cathodes. (90/5/5 ratio of LVP, Super P Carbon, and PVDF.) These composite cathodes were used in lithium anode, LiPF6 liquid electrolyte, Swage-type cells that were galvanostatically cycled from 3.OV to 4.2V and from 3.4V to 4.8V at C/20 rates. Electrochemical impedance spectroscopy was carried out on an LVP / liquid electrolyte / LVP cells from 0.01Hz to 1MHz. Finally...

‣ Evolution of microstructure and crystalline texture in aluminum sheet metal subjected to high strain rate biaxial deformation

Feitler, Isaac Benjamin
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 50 leaves; 2441955 bytes; 2442720 bytes; application/pdf; application/pdf
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Electrohydraulic forming was used to biaxially stretch commercial Aluminum 5052 sheet metal workpieces at a high strain rate. Annealed and unannealed workpieces were formed. Specimens were taken from unformed metal and from the formed workpieces. Microstructures were examined with optical microscopy and pole figures were generated from X-ray diffraction data. Microstructures and crystalline textures were compared between formed and unformed and annealed and unannealed metal specimens, and strains were measured from the formed workpieces.; by Isaac Benjamin Feitler.; Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 2005.; Includes bibliographical references (leaves 49-50).

‣ Computational study and analysis of structural imperfections in 1D and 2D photonic crystals

Maskaly, Karlene Rosera
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 232 p.; 12921362 bytes; 12931189 bytes; application/pdf; application/pdf
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Dielectric reflectors that are periodic in one or two dimensions, also known as 1D and 2D photonic crystals, have been widely studied for many potential applications due to the presence of wavelength-tunable photonic bandgaps. However, the unique optical behavior of photonic crystals is based on theoretical models of perfect analogues. Little is known about the practical effects of dielectric imperfections on their technologically useful optical properties. In order to address this issue, a finite-difference time-domain (FDTD) code is employed to study the effect of three specific dielectric imperfections in 1D and 2D photonic crystals. The first imperfection investigated is dielectric interfacial roughness in quarter-wave tuned ID photonic crystals at normal incidence. This study reveals that the reflectivity of some roughened photonic crystal configurations can change up to 50% at the center of the bandgap for RMS roughness values around 20% of the characteristic periodicity of the crystal. However, this reflectivity change can be mitigated by increasing the index contrast and/or the number of bilayers in the crystal. In order to explain these results, the homogenization approximation, which is usually applied to single rough surfaces...

‣ Characterizing cost and performance of flexibility strategies in autobody manufacturing

Povelaites, Jeffrey C
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 59 leaves; 3951247 bytes; 3953636 bytes; application/pdf; application/pdf
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Consumer demand is hard to predict in any industry, let alone the automotive industry. Vehicle manufacturers try to produce according to what their customers want, but if these wants change, the company is faced with lots of unsold cars and a huge changeover cost. In order to help fight the problems of demand variability, automotive manufacturers have begun the move towards plant flexibility. This includes designing vehicles comprised of similar subassemblies and the development of flexible tooling. The hope is that multiple vehicles can be produced on the same line so if demand starts to fluctuate, they can change the production levels of their styles with minimal lead time. There are a number of different approaches to flexible tooling. One approach using programmable robotic repositionable tools (PRRT) is particularly promising because it can handle a large number of styles and requires low style specific reinvestment costs. This thesis examines the PRRT technology as well as other forms of flexible tooling to understand the conditions under which these approaches make the most economic sense.; (cont.) For this project an algorithm was developed to choose assembly tools based on subassembly characteristics, production levels, style counts...

‣ Hydrogen degradation and microstructural effects of the near-threshold fatigue resistance of pressure vessel steels

Fuquen-Molano, Rosendo
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 200 leaves; 8895488 bytes; 8903973 bytes; application/pdf; application/pdf
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Safety of pressure vessels for applications such as coal conversion reactors requires understanding of the mechanism of environmentally-induced crack propagation and the mechanism by which process-induced microstructures as in thick section weldments affect the fatigue resistance of the structure. At low stress intensities near-threshold [delta]K₀ ([delta]K = Kmax - Kmin), water vapor in the environment was found to produce a pronounced effect on the fatigue resistance for partial pressures as low as 10 torr. In 2 1/4Cr-1%Mo SA378-2-22 steel the crack propagation rates at high load ratio (R = Kmin-Kmax) are increased in the presence of water vapor and the opposite effect is observed at low load ratio. It is proposed that water vapor-containing environments give rise to two mechanisms affecting crack growth rates: embrittlement caused by hydrogen produced in the water-metal reaction; and crack closure, enhanced by the increased surface roughness and the wedging action of the oxidation product. The microstructure is proposed to affect crack propagation rates mainly through crack closure induced by the synergistic effect of fracture surface roughness and oxide produced by fretting.; by Rosendo Fuquen-Molano.; Thesis (Ph. D.)--Massachusetts Institute of Technology...

‣ The role of hydrogen in the growth of carbon nanotubes : a study of the catalyst state and morphology

Kim, Jin Suk Calvin
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 52 leaves; 2308459 bytes; 2309295 bytes; application/pdf; application/pdf
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The role of hydrogen in chemical vapor decomposition (CVD) of C2H4 for growth of carbon nanotubes (CNTs) was investigated. Fe/A1203 (1/10 nm) catalyst layers were used for growth on Si substrates and the times at which H2 was introduced during the 40 minute temperature ramp, 15 minute annealing (without C2H4), and 15 minute growth (during which C2H4 was flowing) stages was varied. When H2 was introduced before heating, CNTs grew to a length of [approx.] 0.3 mm. However, CNT growth was severely suppressed when H2 was introduced at different points during temperature ramp. Recovery of CNT growth was observed when H2 was introduced during the annealing and growth stages. Under optimum conditions, an [approx.] 1 mm thick carpet of CNTs could be obtained. The chemical state and morphology of the catalysts as a function of the time of H2 introduction were examined using XPS and AFM, respectively. We found that the as-deposited state of Fe was an iron oxide, due to reaction with 02 in the atmosphere, and that the H2 reduced the iron oxide to different oxidation states, depending on the time of H2 introduction. AFM inspection showed that surface roughness could also be correlated with areas of vertical CNT growth.; (cont.) A preliminary model for CNT growth in which the oxidation state of iron determines its catalytic activity is proposed...

‣ Development of stable operator splitting numerical algorithms for phase-field modeling and surface diffusion applications

Handler, Matthew Dane
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 37 leaves; 1675815 bytes; 1675298 bytes; application/pdf; application/pdf
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Implicit, explicit and spectral algorithms were used to create Allen-Cahn and Cahn-Hilliard phase field models. Individual terms of the conservation equations were approached by different methods using operator splitting techniques found in previous literature. In addition, dewetting of gold films due to surface diffusion was modeled to present the extendability and efficiency of the spectral methods derived. The simulations developed are relevant to many real systems and are relatively light in computational load because they take large time steps to drive the model into equilibrium. Results were analyzed by their relevancy to real world applications and further work in this field is outlined.; by Matthew Dane Handler.; Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 2006.; Includes bibliographical references (leaves 35-37).

‣ Technology and market analysis of standard electronic photonic package

Abdi, Fatwa Firdaus
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 73 leaves
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Electronic industry will suffer a major turn around in the near future. The current infrastructure will no longer be able to support the increasing data rates. All the disadvantages of copper as current legacy are amplified with the level of bandwidth we are going to experience soon. On the other hand, photonic industry is in the need of finding a new demand source to be able to bring back the state of industry to the "boom" era. With both conditions in mind, it is likely for photonic and electronic industry to emerge. However, the platform for the collaboration has not been mature enough. One of the biggest problems in the photonic industry is the high cost of the package. This, so far, has been one of the major issues holding the industry from gaining back to its golden era. In order to overcome this barrier, standardization has been suggested to be implemented in the industry. This thesis examines the current state of optoelectronic industry, as a convergence of photonic and electronic industry. More specifically, the condition of lack of standardization is analyzed and proven to be the case.; (cont.) Interviewing relevant industry players and working closely with the MIT Communications Technology Roadmap-Integration, Packaging and Interconnects Technical Working Group also determine the reason of the condition. Finally...

‣ Mapping of elastic modulus and hardness in Trochus niloticus seashell nacre by nanoindentation

Villarreal, Julián Enrique
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: :
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Positionally-sensitive nanoindentation was carried out in the freshly-cleaved nacre found in the shell of the gastropod mollusk Trochus niloticus. Nacre is a hierarchical biocomposite composed of mineral tablets of 95 weight % calcium carbonate (CaCO3) in the aragonite mineral form and a biomacromolecular organic matrix. Nanoindentation was carried out in a pattern of square grids of 256 indents at maximum loads of 1 mN and 500 gN. The average elastic modulus and hardness for the 1 mN indents were found to be 97.8 GPa + 6.41 GPa and 5.41 GPa ± 0.49 GPa, respectively, and for the 500 gN indents average elastic modulus of 94.8 GPa ± 7.28 GPa and hardness of 4.89 GPa ± 0.53 GPa. Maps of the 2-D spatial distribution of elastic modulus and hardness for the indent areas were generated. Tapping mode Atomic Force Microscopy was performed on the indented nacre after a treatment of surface etching, which revealed the tablet boundaries in order to correlate qualitatively the topographical features with the properties distribution. The properties distribution maps revealed a non-uniform distribution of nanomechanical properties as well as highly-localized regions in which the values of the properties differed from the average values. Future studies may point to a direct correlation between structural heterogeneity and the properties distribution.; by Julián Enrique Villarreal.; Thesis (S.B.)--Massachusetts Institute of Technology...

‣ Economic and environmental evaluation of end-of-life aerospace aluminum options using optimization methods

Chen, Emily, S.B. Massachusetts Institute of Technology
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 59 leaves
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The benefits of recycling have long been understood and the conspicuous energy savings of secondary aluminum production have caused aluminum recycling to increase. Obsolete aircraft are a valuable source of aluminum scrap and recent efforts to fortify the aerospace aluminum recycling infrastructure have drawn attention to the potential of sophisticated sorting methods to maximize the economic gain of using aerospace scrap in secondary production. The aim of this research was to use linear optimization to assess the economic viability of sorting technologies for enabling wrought products in general and aerospace alloys in particular to be recycled back to high value applications. A chance-constrained model was used to select the alloys that consumed the largest quantity of aerospace alloys in their production, thereby establishing a strategic portfolio of finished goods. Ten of the fifteen alloys in the portfolio were of the 2xxx and 7xxx alloy series that are standard in the production of aerospace components. An aerospace end-of-life case study was performed in which cases varied by their input scrap streams, each having a compositional uncertainty associated with the different degrees of sorting that methods currently in use and technologies in development can achieve. The chance-constrained model calculated the production cost for each case and determined that when aerospace components were identified to the precision of individual alloys...

‣ Financial viability and technical evaluation of dendritic cell-carrying "vaccination nodes" for immunotherapy

Song, Andrew, M. Eng. Massachusetts Institute of Technology
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 69 leaves
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Cancer immunotherapy attempts to stimulate the immune system to reject and destroy tumor cells. Despite the amount of ongoing intensive research to prevent cancer, tumor cells continue to evade immune responses. Currently, dendritic cell vaccines are in development, in which autologous antigen-loaded dendritic cells are injected back into the patient in order to generate an appropriate immune response. Improving upon this idea, members of the Irvine laboratory are in development of an injectable dendritic cell based formulation that gels in situ around the tumor site. In this way, immune cells (most notably T cells) can be recruited and become activated against specific tumor antigens, and (hopefully) kill tumor cells. Recent studies have shown the potential benefit of incorporation of cytokine interleukin-15 complexed with its soluble receptor interleukin-5R[alpha], which is discussed. Economic considerations are also discussed, including topics such as intellectual property, barriers to entry, initial markets and market drivers, and entry into the current supply chain considerations. A business strategy is outlined and evaluated.; by Andrew Song.; Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering...

‣ A technical and economic evaluation of novel pH-responsive core-shell nanoparticles : delivering innovation from laboratory to market

Cho, Eun Chol, M. Eng. Massachusetts Institute of Technology
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 71 leaves
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Many potentially powerful therapeutic strategies for the treatment of disease require the delivery of drugs into the cytosolic or nuclear compartments of cells. Members of the Irvine laboratory have developed a novel pH-responsive core-shell nanoparticle system that can achieve efficient and non-cytotoxic drug delivery into the cytosol. Another advantage is that the shell can be easily modified to bind to different types of drug agents and incorporate ligands for specific cell targeting. Experimental analysis of the newly synthesized nanoparticles with various shell structures has demonstrated that modification of the shell does not compromise their cytosolic delivery. These nanoparticles, if successful, will improve the therapeutic potential of a wide range of drugs. However, critical issues on the research side need to be resolved, and an appropriate intellectual property strategy should be initiated in the near future. Applications to siRNA delivery and vaccines have been examined in depth, as cytosolic delivery is one of the main challenges in these fields. Partnerships with large pharmaceutical companies are critical in order to acquire key patents on siRNA/antigen. Even though the market is competitive, there is a strong demand for innovative delivery platforms; provided that the overall profile of the core-shell nanoparticles is comparable to that of emerging drug delivery systems...

‣ Electrospun nanofibers : opportunities in environment and energy

Mukherjee, Kunal
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 60 leaves
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One-dimensional nanostructures have several attractive material properties compared to their bulk counterparts and have found applications in many novel devices. They have especially shown promise in the fields of renewable energy generation and environmental monitoring by improving solar cells and gas sensors. However difficulties in large scale manufacturing of these nanostructures have prevented most of these devices from entering the marketplace. Electrospinning is a simple, versatile and scalable technique to fabricate one-dimensional nanostructures in the form of nanofibers. It has recently been successfully used to produce semiconducting metal oxide nanofibers which have been used in chemiresistive gas sensors and dye-sensitized solar cells. Electrospun gas sensors and solar cells have already been shown to perform better than many of its competitors in a very short period of time. This coupled with low manufacturing costs and well protected intellectual property makes electrospinning a good candidate to bring the advantages of one-dimensional nanostructures into the marketplace.; by Kunal Mukherjee.; Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 2008.; Includes bibliographical references (leaves 53-56).

‣ Technological assessment and evaluation of high power batteries and their commercial values

Teo, Seh Kiat
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 112 p.
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Lithium Ion (Li-ion) battery technology has the potential to compete with the more matured Nickel Metal Hydride (NiMH) battery technology in the Hybrid Electric Vehicle (HEV) energy storage market as it has higher specific energy and energy. However, in order to improve Li-ion battery technology to fulfill the' HEV energy storage requirements, a very high specific power characteristic is needed to boost its commercial attractiveness. The high specific power characteristic will in turn lead to better a vehicle performances, reduced fuel consumption and emissions. In this thesis, we quantify the fuel savings benefits from HEV, and the marginal value of each W/kg improvement in this battery technology. From the analysis, we conclude that the marginal value of regenerative braking, acceleration, social cost and fuel economy are $13.83, $22.64, $0.9959 and 0.0987 MPG per W/kg per each HEV lifespan respectively. Besides, a variety of start-up companies in various stages of commercialization of these technologies as well as the related intellectual property strategies are also discussed. Finally, suggestion of potential business strategies for licensing and commercializing Li-ion battery technology with respect to HEV energy storage market is presented.; by Seh Kiat Teo.; Thesis (M. Eng.)--Massachusetts Institute of Technology...

‣ Iron-gallium alloys : temperature and field effects on [lambda]100 and magnetic anisotropy measurements

Lichter, Jenny, 1982-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 20 leaves; 1696022 bytes; 1692920 bytes; application/pdf; application/pdf
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Magnetostriction measurements were taken on samples of Fe-Ga alloys (Galfenol) containing between 18% and 35% Ga in fields of 5 kOe to 24 kOe from room temperature to liquid nitrogen temperature. In addition, room temperature magnetic anisotropy measurements were conducted on samples between 8% Ga and 25% Ga. No major hysteresis was found in any of the samples and the field dependence was found to be modest (-2%). Anomalous temperature dependence was found in 22-24% Galfenol, where magnetostriction decreased with decreasing temperature, and 35% Galfenol, where magnetostriction increased dramatically (over 50% to values up to about 250 parts per million) with decreasing temperature. Quenching to retain [alpha]-iron and B2 (CsCl) phases was found to increase magnetostriction, with the B2 structure creating the largest magnetostriction. The reasons for the atypical temperature dependence and the B2 structure enhancing magnetostriction are still unexplained. K anisotropy constants were found to decrease with increasing Ga concentration, but more samples need to be measured to validate this trend.; by Jenny Lichter.; Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, June 2004.; "May 2004."; Includes bibliographical references (leaves 18-19).