并联锂离子电池组的模型化与电流分配

近些年发表了大量关于消除串联电池组能量不均衡方法的文献;然而,关于电池性能的变化对并联电池组的影响的研究还比较少;为探索具有不同特性的电池进行并联联接时的影响,基于锂电池的戴维宁等效电路模型建立了并联电池组的数学模型;在此基础上,通过内阻差ΔR和容量差ΔQ两种参数情况分析了并联电池组内电流分配的基本机制;为进行对比分析,选择了4个不同老化程度的锂电池以构建不同的电池组;采用非线性最小二乘法对模型的未知参数进行辨识,并利用MATLAB进行建模仿真比较;仿真实验结果表明,对于有不同老化程度电池的并联电池组,并联电池组内的电流会发生很大的变化,这可能导致更严重的不一致性问题并进一步加速电池老化。     

Cotton fiber length distribution modality alteration in ginning and mill processing

Mechanical damage in cotton fiber processing both shifts the fiber length distribution and alters its shape. This leads to length distributions with complex shapes, often bimodal, that cannot be classified based on simple summary statistics. In this research, we quantified the distribution departure from unimodality and its alteration from the seed to the card sliver in order to determine where in the cotton process the complex bimodal shape appears, and to identify its potential sources of variability observed at the bale stage. Results presented in this paper indicate that bimodality is a transient state associated with intermediate fiber damage levels starting from the gin stand. The distribution is unimodal or shows a non-significant departure from unimodality at both the low and high damage levels, i.e. seed and card sliver, respectively. Fiber maturity plays a major role in determining the variability of the distribution modality at any processing stages. A mature cotton typically shows an extended intermediate damage state associated with a bimodal distribution, while an immature cotton will reach an advanced damage level from the early stages of mechanical processing, and thus will not exhibit the bimodality that is characteristic of an early/intermediate stage of the fiber breakage process.     

Effects of spandex drawing ratio and weave structure on the physical properties of cotton/spandex woven fabrics

In this experimental study, we investigated the effects of spandex filament drawing ratio and weave structures on the properties of cotton/spandex woven fabrics. One-way analysis of variance was used to explore the significant effects of the independent variables on the fabric properties. A regression analysis was also used to derive regression relationships between each of fabric properties and spandex filament drawing ratio. Our findings show that the spandex drawing ratio and structures of the woven fabrics significantly affect the physical and mechanical properties of the cotton/spandex woven fabrics. Cotton woven fabrics containing spandex show higher contraction, crease recovery, and flexural rigidity with increasing spandex drawing ratio, whereas the rest of fabric properties decreases with the increasing drawing ratio. Because of higher contraction and then higher weight, thickness, and cover factor of cotton/spandex fabrics, unexpected results of fabric air permeability and breaking elongation were detected.     

Outage Probability Analysis of Cooperative Diversity Networks Over Weibull and Weibull-Lognormal Channels

This paper presents the analysis of outage probability for a cooperative diversity wireless network using amplify-and-forward relays over independent non-identical distributed Weibull and Weibull-lognormal fading channels for single as well as multiple relays. To reach that end, a closed-from expression for the moment-generating function of the total signal-to-noise-ratio (SNR) at the destination is derived in terms of the tabulated Meijer’s G-function. Since it is hard to determine the exact probability distribution function of the SNR, a tight lower bound approximation is proposed. Simulation results are presented that show that the outage probability lower bound tends to be tight at high SNR values thus verifying the analytical results. The results also show the potential gain of relaying on the outage probability.     

宫颈湿疣临床诊治研究

目的探讨宫颈湿疣阴道镜下的诊断价值及激光治疗的疗效.方法自1999年9轮?000年9月间就诊于阴道镜门诊的177例患者均作阴道镜检察并作镜下活检.治疗方法CO2激光气化治疗.结果其中经临床诊断为宫颈尖锐湿疣的为43例,经阴道镜诊断为宫颈尖锐湿疣81例,扁平型湿疣80例,故宫颈湿疣的临床诊断检出率24.3%,漏诊率75.7%,阴道镜诊断检出率91.0%,漏诊率9%.在96例扁平型患者中,一次治愈74例(占77.1%),二次治愈20例(占20.8%),三次治愈2例(占2.1%).81例尖锐型患者中,一次治愈78例(占96.3%),二次治愈3例(占3.7%).177例宫颈湿疣,一次治愈率85.9%,二次治愈率98.9%,三次治愈率100%.结论阴道镜检查为诊断宫颈湿疣的一种敏感性高的诊断方法,CO2激光是一种安全,可靠,有效的治疗方法.     

Modeling of filtration through multiple layers of dual scale fibrous porous media

Functionally graded composites exhibit properties within the material that vary gradually without a recognizable boundary. One technique to manufacture functionally graded polymer composites is by liquid composite molding process. In this process, structural fabric layers are stacked in a closed mold and resin is injected into the mold. Particles may be added to the resin to tailor the properties of the final product. The structural fabrics typically consist of yarns or bundles of thousands of micron size fibers woven, stitched, or knitted together, which gives rise to a bimodal distribution of pore sizes; the larger pores in between the bundles and smaller ones within the bundles. The filtration process that takes place during infusion alters the flow resistance of the porous media and complicates the impregnation process. In this study, a vacuum‐assisted resin transfer molding (VARTM) process‐based approach is presented that enables functional grading in composites to obtain a desired distribution in properties. A model of the filtration phenomenon is proposed to predict the concentration distribution of particles within the dual scale fibrous porous media infused under a constant pressure drop. The approach uses Darcy's law and accounts for lowering of the permeability value due to the particle entrapment in the available pores. Experiments are conducted and the concentration of the particles in the fabric is measured. The results compare well with the predictions despite many assumptions made in the model. Nondimensional analysis and parametric study reveals the influence of critical parameters on the final particles concentration gradient. POLYM. COMPOS. 27:570–581, 2006. © 2006 Society of Plastics Engineers     

Phenotypic Characterization and Genotypic Subtyping of Salmonella enterica Serovars Enteritidis and Gallinarum Isolated from Human and Poultry-Related Samples

This study aimed to assess the serotypes, antibiotic susceptibility, and molecular subtyping of Salmonella enterica isolated from food products and human patients with gastroenteritis. A total of 59 isolates were investigated, and the results revealed a predominance of S. Enteritidis with 57.63% (34/59) S. Gallinarum held second with 15.62% (5/32) of total food borne. While, isolates from humans showed 18.51% (5/27) of S. Typhimurium. High level of resistance to nalidixic acid was noted among food strains and 35.29% of human isolates were found to be multidrug resistant. Eight representative isolates were subtyping using three molecular approaches, ribotyping, Multilocus sequence typing (MLST) and Multiple-locus variable number tandem repeat analysis (MLVA). MLST showed three sequence types corresponding to two clonal complexes, (ST-78, CC-4) for S. Gallinarum, (ST-11, CC-4) for S. Enteritidis and (S-367, CC-37) for S. Cerro. While, MLVA generated six different profiles targeting nine loci for S. Enteritidis and S. Gallinarum.     

Variations in essential oil and fatty acid composition during Myrtus communis var. italica fruit maturation

The essential oil and fatty acid composition of Myrtus communis var. italica fruit during its ripening was determined. The effect of the harvesting time on some physical properties of Myrtus fruits, fruit weight and moisture content, were significant. The increase of fruit weight (from 2.54 to 8.79 g% fruits) during ripeness was correlated positively with that of moisture content (from 28% to 72%). Fruit essential oil yields varied from 0.003% to 0.01% and showed a remarkable increase at 60 days after flowering to reach a maximum of 0.11%. Forty-seven volatile compounds were identified in fruit essential oils; 1,8-cineole (7.31–40.99%), geranyl acetate (1.83–20.54%), linalool (0.74–18.92%) and α-pinene (1.24–12.64%) were the main monoterpene compounds. Total fatty acid contents varied from 0.81% to 3.10% during fruit maturation and the predominant fatty acids were linoleic (12.21–71.34%), palmitic (13.58–37.07%) and oleic (6.49–21.89%) acids. The linoleic acid proportions correlated inversely with palmitic and oleic acids during all the stages of ripening.     

Synthesis,characterization, and drug‐release behavior of amphiphilic quaternary ammonium chitosan derivatives

A new type of amphiphilic quaternary ammonium chitosan derivative, 2‐N‐carboxymethyl‐6‐O‐diethylaminoethyl chitosan (DEAE–CMC), was synthesized through a two‐step Schiff base reaction process and applied to drug delivery. In the first step, benzaldehyde was used as a protective agent for the incorporation of diethylaminoethyl groups to form the intermediate (6‐O‐diethylaminoethyl chitosan). On the other hand, NaBH₄ was used as a reducing agent to reduce the Schiff base, which was generated by glyoxylic acid, for the further incorporation of carboxymethyl groups to produce DEAE–CMC. The structure, thermal properties, surface morphology, and diameter distribution of the resulting chitosan graft copolymers were characterized by Fourier transform infrared spectroscopy, ¹H‐NMR, thermogravimetric analysis, differential scanning calorimetry, X‐ray powder diffraction, scanning electron microscopy, and laser particle size analysis. Benefiting from the amphiphilic structure, DEAE–CMC was able to be formed into microspheres in aqueous solution with an average diameter of 4.52 ± 1.21 μm. An in vitro evaluation of these microspheres demonstrated their efficient controlled release behavior of a drug. The accumulated release ratio of vitamin B₁₂ loaded DEAE–CMC microspheres were up to 93%, and the duration was up to 15 h. The grafted polymers of DEAE–CMC were found to be blood‐compatible, and no cytotoxic effect was shown in human SiHa cells in an MTT [3‐(4, 5‐dimethyl‐thiazol‐2‐yl)‐2, 5‐diphenyltetrazolium bromide] cytotoxicity assay. These results indicate that the DEAE–CMC microspheres could be used as safe, promising drug‐delivery systems. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39890.     

灰枣三蒸三晾前后功能成分及抗氧化活性分析

以不同等级（特级、一级、二级）若羌灰枣为原料,测定并比较其三蒸三晾加工处理前后主要功能成分（总黄酮、总多酚、总三萜、总糖和还原糖）和抗氧化活性（DPPH自由基、ABTS+自由基清除能力及总还原能力）。结果显示,特级、一级、二级灰枣经三蒸三晾加工处理后,总黄酮、总三萜、还原糖含量均增加,总多酚、总糖含量降低,其中一级、二级灰枣总黄酮含量显著增加,增加率为32.62%、26.10%,一级灰枣总三萜、还原糖含量显著增加,增加率分别为14.76%、84.35%,而一级灰枣总多酚和总糖含量均降低,二者降低率分别为7.0%、26.92%。3个等级灰枣经三蒸三晾加工处理后,特级、一级、二级灰枣对DPPH自由基清除能力均增强,尤其是一级灰枣的清除能力增强最多,一级灰枣对ABTS+自由基清除能力最强,一级、二级灰枣的总还原能力较强。