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71.
72.
Amit Prakash Siddheswar Maikap Writam Banerjee Debanjan Jana Chao-Sung Lai 《Nanoscale research letters》2013,8(1):379
Improved switching characteristics were obtained from high-κ oxides AlOx, GdOx, HfOx, and TaOx in IrOx/high-κx/W structures because of a layer that formed at the IrOx/high-κx interface under external positive bias. The surface roughness and morphology of the bottom electrode in these devices were observed by atomic force microscopy. Device size was investigated using high-resolution transmission electron microscopy. More than 100 repeatable consecutive switching cycles were observed for positive-formatted memory devices compared with that of the negative-formatted devices (only five unstable cycles) because it contained an electrically formed interfacial layer that controlled ‘SET/RESET’ current overshoot. This phenomenon was independent of the switching material in the device. The electrically formed oxygen-rich interfacial layer at the IrOx/high-κx interface improved switching in both via-hole and cross-point structures. The switching mechanism was attributed to filamentary conduction and oxygen ion migration. Using the positive-formatted design approach, cross-point memory in an IrOx/AlOx/W structure was fabricated. This cross-point memory exhibited forming-free, uniform switching for >1,000 consecutive dc cycles with a small voltage/current operation of ±2 V/200 μA and high yield of >95% switchable with a large resistance ratio of >100. These properties make this cross-point memory particularly promising for high-density applications. Furthermore, this memory device also showed multilevel capability with a switching current as low as 10 μA and a RESET current of 137 μA, good pulse read endurance of each level (>105 cycles), and data retention of >104 s at a low current compliance of 50 μA at 85°C. Our improvement of the switching characteristics of this resistive memory device will aid in the design of memory stacks for practical applications. 相似文献
73.
Experimental investigation of convective heat transfer coefficient of Al2O3/water nanofluid at lower concentrations in a car radiator 下载免费PDF全文
For many years, water and ethylene glycol were used as conventional coolants in automotive car radiators, but these coolants offer lower thermal conductivity than is required. This study is focused on the application of water‐based Al2O3 nanofluid at lower concentrations in a car radiator. The Al2O3 nanoparticles with an average diameter of 50 nm are dispersed in demineralized water at four different volume concentrations (0.1 vol. % to 0.4 vol. %) without any dispersant or stabilizer. Flow rate is varied in the range of 2 l/min to 5 l/min and inlet coolant temperature to the radiator is set to 50 °C, 60 °C, and 70 °C. The results show that the heat transfer coefficient increases with an increase in particle concentration, flow rate, and inlet temperature of coolant and the maximum increase in heat transfer coefficient is 45.87 % compared to pure water. However, the Nusselt number increases with the increase in particle concentration, Reynolds number, and inlet temperature of the coolant. In addition with the experimental study, a regression analysis is performed by using the ANOVA method and generates a correlation for the convective heat transfer coefficient. 相似文献
74.
Amit Singhania Venkatesan V. Krishnan Ashok N. Bhaskarwar Bharat Bhargava Damaraju Parvatalu 《International Journal of Hydrogen Energy》2018,43(8):3886-3891
A highly active and stable catalyst for hydrogen-iodide decomposition reaction in sulfur-iodine (SI) cycle has been prepared in the form of PdCeO2 nanocatalyst by sol-gel method with different calcination temperatures (300 °C, 500 °C, and 700 °C). XRD and TEM confirmed a size around 6–8 nm for PdCeO2 particles calcined at 300 °C. Raman study revealed large number oxygen vacancies in PdCeO2-300 when compared to PdCeO2-500 and PdCeO2-700. With increase in calcination temperature, the average particle size increased whereas the specific surface area and number of oxygen vacancies decreased. Hydrogen-iodide catalytic-decomposition was carried out in the temperature range of 400°C–550 °C in a quartz-tube, vertical, fixed-bed reactor with 55 wt % aqueous hydrogen-iodide feed over PdCeO2 catalyst using nitrogen as a carrier gas. PdCeO2-300 showed hydrogen-iodide conversion of 23.3%, which is close to the theoretical equilibrium conversion of 24%, at 550 °C. It also showed a reasonable stability with a time-on-stream of 5 h. 相似文献
75.
正海尔兹山纪念堂是一个独特的纪念场所。为了纪念耶路撒冷所有阵亡的士兵,设计中包含了他们名字。这是和平年代期冀希望的象征。尽管临近耶路撒冷繁华路段,纪念堂设计为一个平静的圣经式场地,整个空间孤隐而静谧。建筑主体空间通过挖掘山体而成,形成个人或集体纪念活动的私密空间。纪念堂上方的山体,以耶路撒冷石塑造出新的曲线。纪念堂形成一个波形漏斗状结构,缓缓通向天际。这种不规则的涡旋状结构为纪念堂营造出不断变化的自然光。 相似文献
76.
Amit Kumar 《热应力杂志》2018,41(8):1080-1099
A unified enriched finite element (FE) formulation for two generalized thermoelsaticity theories is developed for the transient thermal shock problems in one and two dimensional domains. Both the displacement and temperature field interpolations are enriched with harmonic functions defined in the local element coordinates. The coupled field finite element equations are derived using the generalized Hamilton’s principle and solved directly in time domain using the standard Newmark-β time integration technique as opposed to the transform techniques usually adopted for thermal shock problems. The method is assessed in comparison with the Laplace transform based analytical solutions and FE solutions with dynamic meshing available in the literature. It is shown that the present solution with a static uniform mesh captures the sharp discontinuities in the temperature and displacement fields and the wave properties of heat conduction very accurately, practically eliminating the severe drawbacks of the conventional FE solutions such as the spurious undulations and flattening out, while maintaining better computational e?ciency. 相似文献
77.
3D Numerical study of temperature variation for subsonic rarefied gas flow in a microchannel is carried out using an in-house MPI-based parallelized DSMC code. The temperature drop in the microchannel decreases with an increase in the aspect ratio whereas it increases with an increase in the pressure ratio, the cross-aspect ratio (CAR), and the Knudsen number. 3D and 2D simulations results are compared and effect of the CAR and Knudsen number are brought out. Finally, a correlation that predicts the temperature drop is formulated along with a list of conditions that ensures a near isothermal flow. 相似文献
78.
79.
Das Ashmi Chakraborty Dwari Santanu Bage Amit 《Wireless Personal Communications》2018,98(4):3477-3503
Wireless Personal Communications - This paper presents method of moment based analysis of E Plane and H-Plane T-junctions to find the field distributions on different transverse and longitudinal... 相似文献
80.
Amit Md. Estiaque Arefin Md. Tariqul Islam Md. Shamim Akhter 《The International journal of environmental studies》2018,75(5):732-739
Today, urbanised people spend most of their time in indoor environments, and the risk of exposure to toxic materials in an indoor environment is of great concern. This paper considers sources for the inhalation risk of aerosol sprays by measuring the particle size distributions of some of the most popular products that are commercially available in Bangladesh, and examines the degree of toxicity and the health risk via the respirability of the products. Results show that thoracic and respirable fractions of the suspended particulate matter are present in the tested samples and hence the spray products may pose a significant health risk. 相似文献