针状电极场的数值模拟及实验研究

利用MATLAB编程实现了任意倾斜多针状电极电流所产生电场的数值计算,实现了三维图形的绘制。为实现模拟与实验的相互验证与指导,设计了多针状电极场分布实验测量方法,通过自己组装的实验仪器测量了电极周围的电势分布,实验与数值模拟结果比较吻合,取得了很好的一致性。     

石墨烯/聚吡咯/棉纱线电极的制备和性能研究

柔性超级电容器对电极材料的导电性和电容性具有较高的要求。为提高纱线电极的导电性和电容性,以棉纱线、氧化石墨烯(GO)、吡咯(Py)为原料,采用化学还原法和原位化学聚合法,制备石墨烯(rGO)/聚吡咯(PPy)/棉纱线电极。观察聚合前后电极材料的表面形貌,测试聚合前后电极材料的电阻和电化学性能,结果显示:PPy颗粒包覆在rGO/棉纱线表面;rGO/PPy/棉纱线电极单位长度的电阻降到373Ω/cm;当电流密度为105.00mA/cm~3时,rGO/PPy/棉纱线电极体积比电容为27.63F/cm~3,电化学性能明显好于未加入PPy的rGO/棉纱线电极的性能。PPy的引入有利于改善rGO/棉纱线电极的导电性和电容性,适用于制备柔性超级电容器的电极材料。     

1／2,1／4,1／8导体球壳电像电静电场分布

采用电像法研究和讨论了导体壳（表面电势为零的情形）内电荷在空间产生的电像与壳内的电场分布。分别分析计算了１／２、１／４、１／８球壳三种没情形下的电势和电场强度。     

1/2、1/4、1/8导体球壳电像与静电场分布

采用电像法研究和讨论了导体壳（表面电势为零的情形）内电荷在空间产生的电像与壳内的电场分布．分别分析计算了１／２、１／４、１／８球壳三种不同情形下的电势和电场强度．     

氧化电位自动测示记录装置

在制碘工艺中,氧化电势的控制是很重要的。一般测试氧化电势,都是采用甘汞电极和铂电极进行测试,如果不连续测定,电极的极化还不成为一个严重问题,因此可以采用铂电极测试其氧化电势;但是应用在生产工艺中的连续测试和控制上。电极的极化问题就暴露出来了。为了解决这个问题,有人在电极对的选择上做了些工作。目前在制碘工艺上氧化电势的连续测定所采用的铁、铂、电势对,就是避免电流极化的。随着新的工艺提出了井卤不加酸制碘,这对电势的测定必须在近中性条件下进行。铂电势的极化问题,变得非常严重,因而于新的电极对的探索工作就又必要了,这次在蓬莱盐厂党委的具体领导下,就井卤不加酸制碘的中间试验,对新电极对探索做了一点初步工作,为了配合新电极对的特点,也改制了测定仪器。     

二球体重合部分导体周围空间静电场研究

讨论了二球体重合区域导体壳(表面电势为0的情形)内电荷在空间产生的电场分布.在球面夹角为π/n(n=2,3,…),点电荷位于重合区域中通过二球心的平面上的情况下,采用保角变换和电像法对空间像电荷的分布、电势和场强作了分析求解.     

多针状电极场空间分布的MATLABGUI创建及实现

针对多针状电极场数值模拟结果,利用MATLAB编程和MATLAB的GUIDE开发了复杂多针状电极场的图形用户界面(GUI),实现了复杂多针状电极场的三维和二维空间分布图形显示,可以方便地同时显示任意根、任意长、任意方向放置的多针状电极场的数值计算的结果,实现了复杂多针状电极场空间分布的可视化,为更好地应用多针状电极带来了方便。     

非均匀带电圆环空间电势和电场分析

带电细圆环是电磁学理论及应用中的基本模型,研究其产生的电场在空间的分布具有重要意义。利用电多极矩法计算非均匀带电圆环的电势和电场强度,并利用Matlab图形处理功能绘图,研究非均匀带电圆环在空间任一点的电势及电场分布,计算出轴线上的电势并与均匀带电圆环的电势进行比较。结果表明,利用Matlab获得的结果是可靠的,该结论对研究电磁场的分布提供了一种可行的方法,对研究与静电放电有关的电磁场的特性有一定的指导意义。     

角域静电场的电像法求解(二)

用几何求电像的方法研究和讨论了二面角导体(表面电势为0的情形)外的角域內电荷在角域空间中任一点产生的电势和电场强度.分别分析计算了π、π/2、π/3、π/6以及π/n(n=1,2,3,…)角域各种不同情形下的像电荷分布、电势和电场强度.     

用nullator组元电荷状态变量法分析SCN

描述了一种适用于寄生电容不灵敏开关电容网络(SCN)快速有效的分析方法．提出了有限增益运放的电容-nn模型，定义了nullator组元割集,在此基础上得到了用观察法直接形成组元电荷状态方程的方法，给出了计算实例。     

医用口罩熔喷非织造布电极的制备及其电化学性能

为实现废弃医用口罩在储能领域中的高值化应用,采用镀银和涂炭方法对一次性医用口罩的中间层熔喷非织造布表面进行处理制备双电层电极,最后组装成超级电容器器件。分别采用循环伏安法、恒电流充放电法和交流阻抗法测试熔喷非织造布电极和所组成器件的电化学性能。结果表明:当电流密度为1 A/g时,所得电极比电容可达298 F/g,在电流密度为20 A/g下其比电容为224 F/g,展现出较高的倍率性能(75%),电极的电荷转移内阻和等效串联内阻分别为0.86和0.15 Ω;在功率密度为125 W/kg下,超级电容器器件的能量密度达到9.7 W·h/kg,此外经过10 000次充放电后,器件的比电容保持率高达99.8%,展现出优异的循环稳定性。     

圆形纬编针织物电极导电性能及电阻理论模型构建

为从理论上指导基于纬编针织物电极智能腿套的设计,建立电阻模块理论模型,选用2种导电材料、3种组织结构和4种电极尺寸制作了24种腿套试样,测试其热定形前后腿套电极部位的导电性能,探讨不同因素对织物电极等效电阻的影响,同时建立织物电极等效电阻线性拟合模型。结果表明:不同因素对织物电极导电性能均有显著影响,且原料对导电性能影响最显著;镀银纱织物热稳定性较好,对于需热定形处理的导电织物可选用镀银锦纶纱为原料;建立的电阻模块理论模型可用于定量分析和预测织物电极的等效电阻。     

辅助电极作用下双喷头静电纺丝电场及射流受力分析

 双喷头静电纺丝过程中,喷头间电场相互干扰,带有相同电荷的两条射流相互排斥,使得纺丝连续性下降且纤网分布不均匀。本文通过在两喷头处各装有相同形状的圆锥形辅助电极来降低电场间的干扰,实验表明,装有圆锥形辅助电极的双喷头静电纺丝射流连续性好,纤网分布均匀且纤维直径更细。最后通过Ansoft Maxwell 3D电磁场分析软件对静电纺丝电场进行建模仿真,并模拟射流受力,从而进一步阐明辅助电极屏蔽电场的作用。     

Simulation of the distribution of current density in the brain of slaughter pigs with the finite element method

The current density in the brain of a slaughter pig during electric stunning was calculated and visualised with an finite element method computer model. The anatomic model of the pig’s head was constructed with the computer programme Ansys. Ansys offers the possibility of calculating the current density between electrodes in any position using the mathematical “finite element method” model. After calculation the current density distribution can be visualised in planes in any direction through the pig’s head.

Our simulation confirmed the common practice of positioning the electrodes for electric stunning either eye to eye or eye to ear, because the highest current density through the brain was calculated for these positions. Setting the electrodes further caudally reduced the current density remarkably and, stunning is therefore not guaranteed.

Additionally, this model showed for the first time that, due to their lower resistance, the nervus opticus and blood vessels conduct the current like wires into the brain.     

Ion implantation: effect on flux and rejection properties of NF membranes

Nanofiltration (NF) membranes typically carry a net electric charge, enabling electrostatic interactions to play a pivotal role in the rejection of species such as metals, nitrates, and other charged contaminants. In this study, two types of polymeric NF membranes, polyamide and cellulose acetate, were modified by ion implantation to increase the effective surface charge of the membranes. The modified membranes contain implanted ions in the membrane matrix, inducing a discrete, permanent charge in the active membrane layer. The presence of a permanent charge in the membrane matrix allows for increased electrostatic repulsive forces throughout the entire pH range. Streaming potential measurements were conducted as a function of pH for the modified and unmodified membranes to determine the effect of ion implantation on the zeta potential of the membranes. Rejection experiments were performed in order to quantify the effect of increased electrostatic repulsion on ion rejection, and flux measurements quantified the effect of the modification on permeability. Results indicate that electrostatic interactions near the membrane surface can affect rejection; however, the extent of the effect of increased membrane charge depends on physical-chemical characteristics of the membrane. Increased negative zeta potential of the modified membranes resulted in slightly higher rejection of salts with divalent co-ions from the membrane, with less increase observed with salts of monovalent co-ions. Modified membranes were less permeable than the unmodified membranes. Results of this research hold implications in membrane synthesis and modification studies as well as choice of membranes for water treatment applications.     

Influence of Variety,Moisture Content,Kernel Size and Applied Current Frequency on the Electric Properties of Wheat Grain

The work aimed at determination of electric properties of wheat grain in dependence on its variety, moisture, geometrical features of kernels and applied current frequency. Wheat grain of 4 Polish winter varieties: Korweta, Juma, Mikon and Kobra from harvest 2001 were used as the material for study. Grain was sized into 3 fractions: (1) > 2,8mm, (2) 2,5–2,8mm, and (3) 2,2–2,5mm. Basic geometrical features were determined for not sorted grain (control sample) and its three fractions by the use of digital image analysis. Electric properties of grain (at 11% and 15% moisture content) have been performed with the Hewlett Packard 4263B meter. Measurements of impedance, resistance, admittance, conductance, as well as equivalent parallel capacitance and equivalent series capacitance were made. Obtained results were subjected to statistical analysis with the use of Statistica? programme. Changes in electric properties of grain significantly depended on all of studied factors. Most of all significant correlations appeared between geometrical features and studied electric properties of grain of 15% moisture. Statistical analysis of the results proved significant linear correlations between electric properties of kernels and their length, perimeter and circularity coefficient R_C2 at higher measurement frequencies.     

Constrained optimization of L-lysine production based on metabolic flux using a mathematical programming method

Constrained optimization for microbial fermentation was studied. For optimization, we used not the maximum principle but a nonlinear programming method because of the need to consider many metabolic reactions. In the case of L-lysine fermentation, the optimization problem in L-lysine production was formulated as a nonlinear programming problem. In general, the state equations based on material balances are represented as differential equations, but such equations which are dependent on time can not be applied to a nonlinear programming problem. Therefore, the state equations were made discrete in a time base, and a new single vector which is not dependent on time was substituted. From these formulae, the objective function and the constraints using nonlinear programming problem were defined as the amount of L-lysine produced, and as a metabolic reaction model and empirical equations, respectively. Computer program was developed to solve this constrained nonlinear programming problem. The applied algorithm of the computer programming was a sequential quadratic programming method (SQP method). When the constrained nonlinear programming problem is solved using the SQP method, the maximum amount of L-lysine produced and the optimal feeding rate of L-threonine could be calculated. From the calculated results, it was clear that introduction of the equality and inequality constraints was easy. L-Lysine at a concentration up to 75.3 g/l could be produced when the fermentation was carried out under optimal conditions.     

Simulation study on covariance component estimation for two binary traits in an underlying continuous scale

The usefulness of the variance and covariance component estimation methods based on a threshold model was studied in a multiple-trait situation with two binary traits. Estimation equations that yield marginal maximum likelihood estimates of variance components on the underlying continuous variable scale and point estimates of location parameters with empirical Bayesian properties are described. Methods were tested on simulated data sets that were generated to exhibit three different incidences, 25, 15, and 5%. Results were compared with analyses of the same data sets with a REML method based on normal distribution and a linear model. Heritabilities and residual correlations calculated from discrete observations were transformed to underlying parameters. In estimation of heritabilities, all methods performed equally well at all incidence levels and with no detectable bias. As suggested by threshold theory, the genetic correlation was accurately estimated directly from the observations without any need of correction for incidence. Marginal maximum likelihood estimates of genetic correlations were similar to linear model estimates; discrepancies from the true parameters were consistent with both methods. In estimation of residual correlations, the method with the linear model approach yielded satisfactory estimates only at the highest incidence level, 25%. For 5% incidence, the uncorrected estimate of residual correlation was 50% less than the true value, and after correction for incidence, the parameter was overestimated by 90%. The estimates of residual correlation from the threshold model were regarded fair, except at the lowest level of incidence, where the estimate was 27% higher than the true value. Results indicated that when an accurate estimate of residual correlation is needed, the marginal maximum likelihood estimates are superior to the estimates calculated with the linear model. Using correction for the incidence level for residual correlation did not work well except at the highest incidence level.