不同热管理方案下锂离子电池模组温度特性分析

针对锂离子动力电池在不同条件下电池模组温度变化及热失控传播特性不明晰的问题,提出了基于不同填充材料的电池热管理模拟方案。利用COMSOL Multiphysics软件,以18650电池为研究对象,建立锂离子电池模组热电耦合模型,分析不同填充材料下充放电倍率、液冷流量、液冷管排数对正常电池模组温度的影响;探究不同填充材料对电池模组热失控传播的影响;结合电池热失控试验数据验证模型准确性。结果表明,填充材料和管排数对电池正常模组温度影响较大;填充材料为石墨时最佳液冷管排数为8根;PCM材料能将对热失控传播时间控制在40~50 s/颗,相比于石墨具备明显优势。

自然光条件下光伏组件模型改进研究

为了使太阳电池的二极管模型更好地适用于户外自然光条件,结合实测参数,改进已有的温度模型和照度模型,给出了一种利用短路电流ISC、开路电压VOC、最大功率点电压Vmpp、最大功率点电流Impp确立模型参数、光照强度和组件温度,确定I-V输出的光伏输出预测模型。采集了屋顶光伏系统的环境参数(照度G-温度T)和电气参数(输出I-V曲线)作为实测参考。在给定光照-温度(G-T)情况下,计算现有模型和改进模型的ISC、VOC输出预测值,与实测参考值进行比较,发现改进模型的预测值更接近于实测值。采用Matlab-Simulink进行模拟,可以得到任意照度和温度下的I-V曲线,通过模拟曲线与真实测量曲线进行对比,发现有较好的吻合度。因此改进模型能够在给定光照和温度数据下,更准确地预测光伏组件输出。

Electroplastic effect in AZ31B magnesium alloy sheet through uniaxial tensile tests

The electroplastic effect in AZ31B magnesium alloy sheet was investigated through uniaxial tensile tests. In order to show the athermal effect of the electrical pulses, two types of uniaxial tensile tests at the same testing temperature were carried out： uniaxial tension in environmental cabinet and uniaxial tension with electrical pulses. In addition, the distribution of temperature field in the cross-section area during uniaxial tension with electrical pulses was simulated. The results show that the distribution of temperature field along the cross-section area is homogeneous. By comparing the true stress？true strain curves of AZ31B alloy under uniaxial tensile tests, the athermal effect with electrical pulses was confirmed. The microstructure evolution after the uniaxial tension was studied by optical microscopy. The results indicate that the electrical pulses induced dynamic recrystallization plays an important role in the decrease of flow stress. Finally, a flow stress model of AZ31B sheet taking the influence of electroplastic effect into account was proposed and validated. The results demonstrate that the calculated data fit the experimental data well.

Intercomparison of different physics schemes in the WRF model over the Asian summer monsoon region

Enhancing the ability of the WRF model in simulating a large area covering the West Pacific Ocean, China's Mainland, and the East Indian Ocean is very important to improve prediction of the East Asian monsoon climate. The objective of this study is to identify a reasonable configuration of physical parameterization schemes to simulate the precipitation and temperature in this large area. The Mellor-Yamada-Janjic （MYJ） and Yonsei University （YSU） PBL schemes, the WSM3 and WSM5 microphysics schemes, and the Betts-Miller-Janjic （BMJ） and Tiedtke cumulus schemes are compared through simulation of the regional climate of summer 2008. All cases exhibit a similar spatial distribution of temperature as observed, and the spatial correlation coefficients are all higher than 0.95. The cases combining MY J, WSM3/WSM5, and BMJ have the smallest biases of temperature. The choice of PBL scheme has a significant effect on precipitation in such a large area. The cases with MYJ reproduce a better distribution of rain belts, while YSU strongly overestimates the precipitation intensity. The precipitation simulated using WSM3 is similar to that using WSM5. The BMJ cumulus scheme combined with the MYJ PBL scheme has a smaller bias of precipitation. However, the Tiedtke scheme reproduces the precipitation pattern better, especially over the ITCZ.

Effects of Atomic Mixing in Inertial Confinement Fusion by Multifluid Interpenetration Mix Model

The effects of atomic-level rnixing are systemically investigated in a multifluid interpenetration mix model ,and results are compared with the single-fluid model＇s simulations and experimental data. It is shown that increasing the model free parameter α, shock Mach number, and the initial density discontinuity makes the mix length and fraction of mixing particle increase, resulting in the lower shock temperatures compared with the results of single-fluid model without mixing. Recent high-compressibility direct-drive spherical implosions on OMEGA are simulated by the interpenetration mix modal. The calculations with atomic mixing between fuel and shell match quite well with the observations. Without considering any mixing, the calculated neutron yields and ion temperatures are overpredicted; while inclusion of the interpenetration mix model with the adjustable parameter α could fit the simulated neutron yields and ion temperatures well with experimental data.

Microwave Induced Plasma Source for Analytical Applications： Experimental and Simulation Study

In this work, experiment investigations and simulation studies of a waveguide-based microwave plasma source operated at 2.45 GHz in atmospheric pressure helium gas are presented. The plasma source has been designed in conjunction with a gas spectrograph as a speciation analysis tool. Emitted He spectra are observed for gas flow rates between （0.2-1） L/min and microwave power in the range （15-150） W. The results obtained demonstrate maximum excitation temperature of about 3800 K and gas temperature of about 2000 K. Mixtures containing small amounts of mercury atoms are considered and the resonant emission of Hg atoms at 253.56 nm is detected. The spectroscopic measurements are completed with a collisional radiative model delivering the electron density and temperature, the amplitude of the electric microwave field, and the population of the excited atomic states for a given absorbed power and gas temperature, The electromagnetic field distribution in the plasma source is obtained by solving Maxwell＇s equations. Electric field strength of several 10^5 V/m is obtained that agrees well with the results of the collisional radiative model. The calculated and measured line intensity ratios of He spectral lines agree within 300/0-40%.

Efficacy of moxibustion by stimulating acupoints of Danzhong(CV 17) and Ganshu(BL 18) on hyperplasia of mammary gland in rats

OBJECTIVE: To evaluate the efficacy of moxibustion, through stimulating acupoints of Danzhong(CV 17) and Ganshu(BL 18) in rats with hyperplasia of mammary gland(HMG) which induced by estrogen and progestogen.METHODS: Thirty female Sprague-Dawley rats were randomly divided into saline control group,HMG model group, and HMG moxibustion group with 10 in each group. Saline control was the group injected by saline. HMG model were created by injection of estrogen and progestogen. Moxibustion group was also injected of estrogen and progesto-gen with moxibustion at the same time. The Changes of nipple diameter and height were measured.The rats' skin temperature was recorded by an infrared thermal camera at the nipples, mammary areas,Danzhong(CV 17) and Ganshu(BL 18). Pathological changes of mammary gland in rats were also observed under light microscope.RESULTS: The diameter and height of the nipples in model group were prominently bigger and higher than that in control group(P < 0.01). The diameter and height in moxibustion group were prominently smaller and lower than that in model group(P < 0.01), and there was no significant difference between moxibustion group and control group.Compared with control group, skin temperature of the nipples, mammary area, and acupoints Danzhong(CV 17) and Ganshu(BL 18) decreased prominently in model group(P < 0.01-0.05). Compared with model group, skin temperature of that in moxibustion group increased prominently(P <0.05).CONCLUSION: Treatment with moxibustion can effectively decrease the HMG rats' nipple diameter and height, and increase the skin temperature in HMG model rats at the nipples, mammary areas,Danzhong(CV 17) and Ganshu(BL 18). This study convinces the therapeutic effect of moxibustion on mammary gland hyperplasia.

TWO-DIMENSIONAL FINITE ELEMENT MODEL OF TEMPERATURE DISTRIBUTION IN DERMAL TISSUES OF EXTENDED SPHERICAL ORGANS OF A HUMAN BODY

In the present study the thermal model of skin and subdermal tissues （SST） of human breast have been developed. The human breast is assumed to be spherical in shape with upper hemisphere projecting out from the trunk of the body and lower hemisphere is considered to be a part of the body core. The upper hemisphere represents the breast and its SST region is divided into three layers namely epidermis, dermis and subdermal tissues. The inner part of the breast represents the core/shell of the breast. The outer surface of the breast is assumed to be exposed to the environment from where the heat loss takes place by conduction, convection, radiation and evaporation. The heat transfer from core to the surface takes place by thermal conduction and blood perfusion. Also metabolic activity takes place at different rates in different SST layers of the breast. Boundary conditions have been framed on the basis of physical conditions. A finite element model has been developed for a two-dimensional steady state case.

Composition dependent elastic modulus and phase stability of Ni_2MnGa based ferromagnetic shape memory alloys

Ni2MnGa based ferromagnetic alloys are ideal candidates for applications such as actuators, magnetic refrigerators or magne-tostrictive transducers due to their attractive properties such as magnetic field induced shape memory effect and large magnetocaloric effect. The properties of these alloys （e.g., the martensitic transformation temperature TM） sensitively depend on the composition. Understanding the composition dependence of these properties so as to design the alloy as desired is one of the main research topics in this area. In recent years, we have investigated the composition dependent elastic modulus and phase stability of Ni2MnGa-based alloys by using a first-principles method, in hope of clarifying their connection to the properties of these alloys. In this article, we review the main results of our investigations. We show that the tetragonal shear modulus C＇ is a better predictor of the composition dependent TM than the number of valence electrons per atom （e/a） since the general TM-C＇ correlation works for some of the alloys for which the TM-ela correlation fails, although there exist several cases for which both the general TM-C＇ and TM-ela correlations break down. Employing the experimentally determined modulation function, the complex 5-layer modulated （5M） structure of the martensite of Ni2MnGa and the Al-doping effect on it are studied. We find that the shuffle and shear of the 5M structure are linearly coupled. The relative stability of the austenite and the marten- sites is examined by comparing their total energies. The non-modulated martensite β＇″ with the tetragonality of the unit cell c/a〉1 is shown to be globally stable whereas the 5M martensite with c/a〈1 is metastable. The critical Al atomic fraction over which the martensitic transformation between the 5M martensite and austenite cannot occur is predicted to be 0.26, in reason- able agreement with experimental findings.