Equal-channel angular pressing （ECAP） is a prominent technique that imposes severe plastic deformation into materials to en- hance their mechanical properties. In this research, experimental and numerical approaches...
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Equal-channel angular pressing （ECAP） is a prominent technique that imposes severe plastic deformation into materials to en- hance their mechanical properties. In this research, experimental and numerical approaches were utilized to investigate the mechanical prop- erties, strain behavior, and damage prediction of ECAPed 7025 aluminum alloy in various conditions, such as die channel angle, outer comer angle, and friction coefficient. Experimental results indicate that, after the first pass, the yield strength, ultimate tensile strength, and hardness magnitude are improved by approximately 95%, 28%, and 48.5%, respectively, compared with the annealed state, mainly due to grain re- finement during the deformation. Finite element analysis shows that the influence of die channel angle is more important than that of outer comer angle or friction coefficient on both the strain behavior and the damage prediction. Also, surface cracks are the main cause of damage during the ECAP process for every die channel angle except for 90°; however, the cracks initiated from the neighborhood of the central re- gions are the possible cause of damage in the ECAPed sample with the die channel angle of 90°.
We discuss fabrication and characterization of TSVs filled with carbon nano-materials (CNM) for dual function of sensing and vertical interconnect for hostile environment applications (Corrosive High Temperature and P...
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We discuss fabrication and characterization of TSVs filled with carbon nano-materials (CNM) for dual function of sensing and vertical interconnect for hostile environment applications (Corrosive High Temperature and Pressure). Nano-composites, made by functionalization of CNTs were integrated using dispersion in epoxy resin and inkjet techniques to fill up the TSVs and provide sensing surface. The results reveal ability for the nano-composite to fill vias with electrical conductivity path and sensing established through the wafer backside.
作者：
Youm, YoungilSchool of Mechanical
Advanced Material Engineering Ulsan National Institute of Science and Technology Korea Republic of
This is the survey paper on the role of kinematics in robot development. The robot is considered as a form of mechanical systems which includes closed-chain loop system, open-chain loop system and closed and open swit...
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Spatial atomic layer deposition (S-ALD) is a potential high-throughput manufacturing technique offering fast and large scale ultrathin films deposition. Here, an S-ALD system with modular injectors is introduced for f...
Spatial atomic layer deposition (S-ALD) is a potential high-throughput manufacturing technique offering fast and large scale ultrathin films deposition. Here, an S-ALD system with modular injectors is introduced for fabricating binary oxides and their nanolaminates. By optimizing the deposition conditions, both ZnO and TiO2 films demonstrate linear growth and desired surface morphology. The as-deposited ZnO film has high carrier mobility, and the TiO2 film shows suitable optical transmittance and band gap. The ZnO/TiO2 nanolaminates are fabricated by alternating substrate movement between each S-ALD modular units of ZnO and TiO2. The grazing incidence x-ray diffraction spectra of nanolaminates demonstrating the signature peaks are weaker for the same thickness nanolaminates with more bilayers, suggesting tuning nanolaminates from crystalline to amorphous. Optical transmittances of ZnO/TiO2 laminates are enhanced with the increase of the bilayers' number in the visible range. Refractive indices of nanolaminates increase with the thickness of each bilayer decreasing, which demonstrates the feasibility of obtaining desired refractive indices by controlling the bilayer number. The electronic properties, including mobility, carrier concentration, and conductivity, are also tunable with different bilayers.
In this paper,computational fluid dynamics（CFD） method is used to research and compare the inhalation pressure drop reduction and heart rate prediction for APR and *** was improved according to the dual inlets of AP...
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In this paper,computational fluid dynamics（CFD） method is used to research and compare the inhalation pressure drop reduction and heart rate prediction for APR and *** was improved according to the dual inlets of APR,which does not feature a one-way inhalation *** results indicate that the inhalation pressure drop of APR（22.2 Pa,85 L/min） is 82.3% lower than that of APR（125.4 Pa）.Consider the case of APR mounted with canister A and B,the inhalation pressure drop of APR mounted with dual canister B（206.4 Pa,85 L/min） is 61.2% lower than that of APR mounted with canister B（531.5 Pa）.Using Li's prediction equation of inhalation pressure drop and heart rate,under high exercise condition of P = 120 W,the predicted Hr/Hrmax for APR mounted with dual canister B is 74.3%,which is 8.6% lower than the experimental value of APR mounted with canister A（82.9%）.In addition,the Hr/Hrmax is lower than the anaerobic threshold（Hr/Hrmax = 80%）,thereby preventing fatigue in users resulting from anaerobic *** results verified that the dual inlets design substantially reduce inhalation pressure drop while decelerating users' heart rate.
Attenuation of short, strongly nonlinear stress pulses in chains of spheres and cylinders was investigated experimentally and numerically for two ratios of their masses keeping their contacts identical. The chain with...
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Attenuation of short, strongly nonlinear stress pulses in chains of spheres and cylinders was investigated experimentally and numerically for two ratios of their masses keeping their contacts identical. The chain with mass ratio 0.98 supports solitary waves and another one (with mass ratio 0.55) supports nonstationary pulses, which preserve their identity only on relatively short distances, but attenuate on longer distances because of radiation of small amplitude tails generated by oscillating small mass particles. Pulse attenuation in experiments in the chain with mass ratio 0.55 was faster at the same number of the particles from the entrance than in the chain with mass ratio 0.98. It is in quantitative agreement with results of numerical calculations with effective damping coefficient 6 kg/s. This level of damping was critical for eliminating the gap openings between particles in the system with mass ratio 0.55 present at lower or no damping. With increase of dissipation numerical results show that the chain with mass ratio 0.98 provides faster attenuation than the chain with mass ratio 0.55 due to the fact that the former system supports the narrower pulse with the larger difference between velocities of neighboring particles. The investigated chains demonstrated similar behavior at large damping coefficient 100 kg/s.
Biogas fuel is a sustainable and renewable fuel produced from anaerobic digestion of organic matter. The biogas fuel is a flammable mixture of methane and carbon dioxide with low to medium calorific values. Biogas is ...
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Biogas fuel is a sustainable and renewable fuel produced from anaerobic digestion of organic matter. The biogas fuel is a flammable mixture of methane and carbon dioxide with low to medium calorific values. Biogas is an alternative to conventional fossil fuels and can be used for beating, transportation and power generation. CFD （computational fluid dynamic） analysis of the combustion performance and emissions of biogas fuel in gas turbine engines is presented in this study. The main objective of this study is to understand the impact of the variability in the biogas fuel compositions and lower heating values on the combustion process. Natural gas, biogas from anaerobic digester, landfill biogas, and natural gas/biogas mixture fuels combustion were investigated in this study. The CFD results show lower peak flame temperature and CO mole fractions inside the combustor and lower NOx emissions at the combustor exit for the biogas compared to natural gas fuel. The peak flame temperature decreases by 37% for the biogas landfill （COJCH4 = 0.89） and by 22% for the biogas anaerobic digester （CO2/CH4 = 0.54） compared to natural gas fuel combustion. The peak CO mole fraction inside the combustor decreases from 9.8 × 10-2 for natural gas fuel to 2.22 × 10-4 for biogas anaerobic digester and 1.32 × 10-7 for biogas landfill. The average NOx mole fraction at the combustor exit decreases from 1.13 × 10-5 for natural gas fuel to 0.40 × 10-6 for biogas anaerobic digester and 1.06 × 10-6 for biogas landfill. The presence of non-combustible constituents in the biogas reduces the temperature of the flame and consequently the NOx emissions.
Most solar cell manufacturing plants and research laboratories in the U.S. use non-renewable energy for their operations. This energy paradox must be addressed, especially due to the increased spending toward photovol...
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Most solar cell manufacturing plants and research laboratories in the U.S. use non-renewable energy for their operations. This energy paradox must be addressed, especially due to the increased spending toward photovoltaic (PV) technology research and manufacturing fueled by the growing demand for renewable energy supply. At the same time, it is also important that the scientific community be made aware of the energy cost of energy research. While keeping scientific discovery a priority, it must be understood that energy is precious and must be conserved, including at the research and development stage of a product's life cycle. With energy conservation in mind, a case study was conducted to quantify the energy demand for the research phase of an emerging PV technology and identify energy intensive components. The test-bed system chosen for this study was a quantum-wire (QWR) based intermediate band solar cell grown by molecular beam epitaxy (MBE) and fabricated by photolithography. This paper presents the results of the energy demand analysis performed on the QWR-based solar cell research test-bed system. Life cycle assessment (LCA), an internationally accepted tool for energy and sustainability analysis, was chosen as the methodology for conducting this case study.
Lithium-ion batteries as a new clean energy with high specific energy and excellent cycle performance and long life serve widely as the power source for many portable electronic devices. However, their power and energ...
Lithium-ion batteries as a new clean energy with high specific energy and excellent cycle performance and long life serve widely as the power source for many portable electronic devices. However, their power and energy densities need to be further increased particularly for the application in electric vehicles. It is important to develop high capacity anode materials to increase the energy density of lithium-ion batteries as the anode material is one of the key factors affect the performance of lithium-ion batteries. SnSb intermetallic alloys are attractive materials as a potential substitute for the conventional graphite anode because their theoretical capacity of SnSb alloys has been estimated to be superior to that of graphite. However, its practical use is hampered by their large volume change during alloying and de-alloying reaction with Li+, as the continuous volume change during cycling will cause the mechanical pulverization resulting in poor cyclability and cracking of the electrode. Various strategies have been brought forward to improve the cycling stability, for example, preparing thin film materials or nanostructured materials. nanostructured alloy anodes have shown an improved cycle lifetime because nanostructured alloy anodes can accommodate the large volume change and maintain the structural integrity of the electrode during the lithiation/de-lithiation process. In this paper, a nanostructured SnSb anode for Li-ion battery has been prepared by a two-step electrode design consisting of the electrochemically assisted template growth of Cu nanopillars onto a current collector followed by electrochemical plating of SnSb, there among, Cu nanopillars current collector was obtained by P. Simon's method. We try to take advantage of the nanostructuration of our electrodes to buffer the mechanical strains occurring during the cycling of tin and antimony with Li+, thanks to larger free space available for alloy–dealloying reactions, delivers a high cycle life a
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