Dielectric and ferroelectric properties of Perovskite Pb(Zr, Ti)O3 films deposited by sputtering on Si substrate

Lead zirconate titanate (PZT) thin films were deposited by radio-frequency (r.f.) magnetron sputtering with stoichiometric single oxide target on silicon substrates. The influence of the growth conditions (with or without substrate heating) and the post-annealing treatments (conventional or rapid thermal annealing) on the film properties in terms of structure and microstructure was systematically evaluated. The electrical properties such as the dielectric constant, the loss factor, the leakage current and the ferroelectric properties have been characterized.     

Solvent-free glycerolysis catalyzed by acetone powder of Nigella sativa seed lipase

The solvent-free glycerolysis of used sunflower oil catalyzed by acetone powder of Nigella sativa seeds was investigated. The highest partial acylglycerols yield was obtained at 60°C. The glycerolysis reactions, conducted at molar ratios of 1:1, 2:1, and 3:1 of oil to glycerol keeping the acetone powder content at 30% based on oil weight and the temperature at 60°C, approached equilibrium after 2 h. The highest partial acylglycerol content of the products was 66% (1:1 molar ratio) and 60% (2:1 molar ratio).     

仿真织物悬垂性影响因素的多元回归分析

采用多 元回归分 析的方 法,研究了 仿真织 物的悬垂 性与 减量 率、减 量前 织物 的经 纬密 度及抗弯长度 之间的 关系,得 出 回归 方 程, 并据 此 进 行仿 真 织物 的 减 量后 悬 垂 性的 预 测; 研 究 结果 表明,悬 垂系数与 减量率、织物经密 存在显著 负相关 ,而与织 物刚柔性 、纬密存 在显著正 相关。     

变长线快速成型机的设计思想和优点

目的　阐述变长线快速成型机的设计思想与优点． 方法　对变长线快速成型机的机械结构及光学系统的设计进行分析． 结果　变长线快速成型机具有结构合理、成型尺寸大、效率高的优点． 结论　变长线快速成型机具有较好的应用前景     

应用放电电流线性衰减模型评价电感性本质安全电路

电感性本质安全电路的放电电流线性衰减模型以放电时间为参数,该参数是电路参数的隐函数．通过分析电弧放电实际过程,引入最小建弧电压,放电时间不但可由电路参数直接表示出来,而且得出放电时间与电感和稳定电流的乘积成正比的结论．此外,进一步应用能量法建立了评价电感电路本质安全性能的判别式,对设计人员预估电路本安性能提供一定帮助．     

煤灰结渣特性的粗集评判

基于粗集理论,提出了煤灰结渣特性的粗集评判模型,由于直接来源于实际观测数据,可靠性高,与其它判别方法相比,能更有效地判别结渣特性。     

Mechanical and Biochemical Characterisation of Wheat Gluten Films as a Function of pH and Co‐solvent

Dispersions of wheat gluten were prepared at different pHs (4, 6 and 11) in the presence or absence of ethanol. Films were obtained after casting suspensions followed by evaporation of the solvent. Films prepared at pH 11 were significantly stronger than the films prepared at pH 4 and 6 with tensile strengths of approximately 7 vs. 2 MPa. With increasing strength, the elongation at break was moderately reduced from approximately 300% to 190%. No significant variations of water vapour transfer rate properties were observed among the films. The solubility of gluten films in aqueous and 1.5% sodium dodecyl sulfate (SDS) solution decreased with increasing pH of films. Tricine sodium dodecyl sulfate‐polyacrylamide gel (SDS‐PAGE) patterns of wheat gluten and film showed the formation of high molecular weight fractions. The amount of free amino groups in the wheat gluten decreased during film formation. Amino acid analysis showed the presence of lysinoalanine (LAL). All these results indicate the formation of irreversible intermolecular cross‐linking upon film formation at pH 11.     

Design Sensitivity Analysis of a Plate-Finned Air-Cooled Condenser for Low-Temperature Organic Rankine Cycles

ABSTRACT

Due to increasing world energy demand and environmental concerns, sustainable energy production has become crucial. Among sustainable energy sources such as solar, wind, and geothermal, industrial waste heat (heat normally released to the environment) has a big potential. Organic Rankine cycles (ORCs) are promising systems for utilizing low-temperature (100–250°C) waste heat. For an ORC system, the condenser is a key component. An accurate condenser design is important for cycle efficiency and system cost. In the literature, there are in-tube condensation correlations that are used to design condensers. However, they are not necessarily valid for low-temperature ORC conditions and working fluids, and that might lead to inaccurate end designs. This study comprises a summarized literature survey about in-tube condensation correlations. Then an iterative heat exchanger design methodology is proposed that allows performing a design sensitivity analysis on a V-shaped condenser within an input range of geometric parameters and boundary conditions. Nineteen correlations are implemented to calculate rating parameters like pressure drops, total transferred heat, overall heat transfer coefficient, size, cost and degree of subcooling. The deviations at these parameters are represented as the coefficient of variation that indicates the design condition regions where the prediction methods differ or not.     

Facilitation of water management in low Pt loaded PEM fuel cell by creating hydrophobic microporous layer with PTFE,FEP and PDMS polymers: Effect of polymer and carbon amounts

Microporous layers (MPLs) were prepared with different hydrophobic polymers to establish water management in polymer electrolyte membrane (PEM) fuel cells. Besides conventionally used polymers polytetrafluoroethylene (PTFE) and fluorinated ethylene propylene (FEP), two different molecular weights (MW) of polydimethylsiloxane (PDMS) polymer were used as hydrophobic materials in MPL. Membrane electrode assemblies (MEAs) having MPLs with low MW PDMS polymer exhibited the best fuel cell performance compared to the PTFE and FEP based ones. Thus it is concluded that PDMS polymer has a great potential to be used as hydrophobic material for MPL to reduce flooding phenomena in PEM fuel cell.