Robust model for optimization of forming process for metallic bipolar plates of cleaner energy production system

Energy production systems such as proton-exchange membrane fuel cell (PEMFC) has a promising future in the cleaner energy market due to zero emissions. Rubber pad forming (RPF) process of metallic bipolar plates of PEMFCs is gaining attention among the researchers. Studies based on design of experiments have been conducted to find the crucial parameters of the forming process. These methods are based on the assumptions of the model structure, correlated residuals, etc., which can cause uncertainty in estimation ability of the model on unseen data. Therefore, the present study focuses on the design of robust models of these parameters for PEMFCs using an optimization approach of genetic programming (GP). The inputs from the experiments considered in GP are radius, the friction coefficient, the filling factor and the minimum thickness. Experiments on PEMFCs validates the performance of the GP models. Further, the relationships between the two inputs and the three outputs for PEMFCs are generated as well as the contributions of each input to each of the output. Optimization of the models generated by GP can further determine the forming quality of metallic bipolar plates of PEMFCs by an appropriate setting of the two inputs.     

Experimental and optimization of material synthesis process parameters for improving capacity of lithium‐ion battery

New methods for synthesis of active materials have been developed to improve capacity and cycle life performance of lithium‐ion batteries. Past studies have focused on routes of development of materials and new processes, which might not be economical for large‐scale production. In this regard, this study examines a widely employed carbothermal reduction technology for the synthesis of lithium‐iron phosphate (LiFePO₄/C) and investigates effects of process conditions during this synthesis on final battery performance. An experimental combined genetic programming approach is used to model the effects of crucial process conditions (sintering time, the carbon content, and the sintering temperature) on the discharge capacity of the assembled battery. Experiments are conducted to collect the discharge capacity data based on varying LiFePO₄/C synthesis conditions, and genetic programming is employed to develop a suitable functional relationship between them. The results show that the battery discharge capacity is controlled significantly by adjusting sintering temperature and carbon content, while the effect of sintering time is found to be insignificant. Further, the interaction effect of the sintering time and carbon content is much more obvious than that of the sintering time and the sintering temperature. The findings from the study pave the way for the optimum design of the synthesis process of LiFePO₄/C for a higher battery performance.     

强脉冲离子束在金属中引起的应力波效应

金属在强脉冲离子束辐照及其后的快速冷却过程中所经历的应力过程是强脉冲离子束金属材料改性的最重要的机制之一。对应于这种过程，金属材料的微观结构和微硬度发生了改变。本文以45＃钢和纯铝为样品，将实验中测量到的不同强度的强脉冲辐照后样品微硬度和微观结构的变化与热力学计算所描述的热力学过程相对照，解释了出现微硬度双峰是由于应力波的形成和传播使然，并预言了由于应力波的在样品背面的反射，在较强能通量的强脉冲离子束辐照下样品背表面一定深度处也会出现微硬度增加的现象，该现象已被实验所证实。     

便携式X射线荧光光谱仪快速鉴别硫熏八角

目的建立用便携式X射线荧光光谱仪快速筛查硫熏八角的方法。方法选定土壤模式测定干燥后新鲜八角含硫量,测定时间80 s,测得硫含量为905~1852 mg/kg。将干燥后新鲜八角含硫量作为参照值,对市售干八角是否硫熏进行快速筛查。同时,按农业部标准检验上述市售八角,并进行判定。结果 8批市售干八角中,7批含硫量远超出参照值,为硫熏八角。1批样品的含硫量在参照值内,为未硫熏的八角。该结果和农业部标准判定结果一致。结论便携式X射线荧光光谱仪能快速准确地筛选出硫熏八角。     

辊压法烟草薄片增强用醚化改性木质纤维的研究

本研究首先通过设计正交实验研究了醚化工艺参数对木质纤维羧基含量的影响;其次探究了羧基含量对纤维形貌、结晶结构、保水值及其在烟草薄片中分散性的影响;最后比较了不同羧基含量的纤维对辊压法烟草薄片的增强效果.结果表明,在实验室条件下,3个工艺参数对纤维羧基含量影响顺序为:反应药品浓度＞浆浓＞反应时间.羧基含量与反应药品浓度成...     

分形几何和动力系统中的一些问题

本文是Zhou与Feng,Nonlinearity,2004的续篇,对自相似集的结构和动力系统提出一些较为深入的问题。     

扩散温度和时间对晶体硅太阳电池性能的影响

研究了薄层方块电阻对单晶硅太阳电池的开路电压(Voc)、短路电流(Isc)、填充因子(FF)和转换效率(η)的影响。通过控制扩散温度和时间制备了具有不同薄层方块电阻的单晶硅太阳电池。结果表明:当扩散温度和时间分别为863℃和1 050 s时,电池性能得到了有效的改善,其平均开路电压、短路电流、填充因子和转换效率分别为0.64 V,5.58 A,0.755和17.3%。     

Robin边界条件下光学CT正向问题的数值模拟

文章研究了Robin边界条件下光学层析成像的正向算法,进行了理论分析,给出了实 验结果,实验结果符合理论分析的结果。并对将Robin边界条件和Dirichlet边界条件下的结果进行比较、分析,得出两者的异同点。     

超声波对胰蛋白酶水解酪蛋白的影响

研究了超声场下胰蛋白酶水解酪蛋白的酶解反应条件与动力学.在超声波频率 20 kHz、作用与间歇时间比为1∶1时,测定了不同功率下胰蛋白酶活性及该酶的最适温度、最适 pH和米氏常数Km 的影响.结果表明,180,225 W功率下,超声10 min的酪蛋白水解率显著高于常规对照组(P<0.05); 225 W超声功率下,在5 ℃,10 ℃,20 ℃下水解率分别比对照组提高 4.4 倍、2.47倍和2.33倍(P<0.01);超声场下胰蛋白酶 Km 值减小,Vm 增大.将胰蛋白酶、底物分别进行超声处理,紫外和荧光光谱分析观察到,超声处理后,酶溶液荧光发射光波长从334 nm移至332 nm,荧光强度提高,表明一定的超声波可能使酶及底物分子构象发生变化,提高胰蛋白酶水解活性.     

不同氨基酸螯合锌对小鼠抗氧化能力的影响

研究了三种形式锌源对小鼠抗氧化能力的影响。选用断奶小鼠(KM种)81只,随机分为三组(硫酸锌组、蛋氨酸锌组和亮氨酸锌组)。实验第一周,饲喂缺锌日粮。实验第8d起,三组饲喂加锌日粮。三种锌源均能提高肝脏、血清锌含量。补锌能使血清MDA含量明显下降,不同锌源间差异不显著(p>0.05)。补锌7d后,三种锌源提高了小鼠总抗氧化能力、总SOD、铜锌超氧化物歧化酶活性、谷胱甘肽含量,蛋氨锌组和亮氨酸锌组优于硫酸锌组酸(p<0.05)。亮氨酸锌,蛋氨酸锌的抗氧化能力优于硫酸锌,氨基酸螯合锌组之间抗氧化能力的差异不大。