基于最小网损的风电场无功优化分配策略

针对含双馈式风电机组的风电场接入系统维持接入点电压稳定性问题,通过分析通辽某风电场的实测数据,分析其无功补偿特点,提出了基于有功最小的无功优化分配策略;构建了以风力发电机、箱式变压器和集电线路有功损耗最小的无功优化分配目标函数,利用等微增率法对其求解;在考虑风电场有功损耗的前提下,充分利用双馈式风电机组无功调节能力,制定了该风电场无功分配方案。仿真结果表明该策略的可行性,对风电系统的经济运行具有一定的参考价值。     

Enhanced photoelectrochemical performance of TiO2 through controlled Ar+ ion irradiation: A combined experimental and theoretical study

Here we demonstrate that the performance of TiO₂ electrodes for photoelectrochemical water oxidation can be effectively enhanced through oxygen vacancy doping. The ion irradiation is a simple method to introduce oxygen vacancies on the surface and into the interior of TiO₂ for making oxygen-deficient titania (TiO_2-x). The TiO_2-x thin films exhibit obvious increase in the performance of photoelectrochemical water splitting under light irradiation. The photoconversion efficiency η of the TiO_2-x photoanode is 0.5-fold higher than that of the pristine TiO₂ photoanode, which benefits from the introducing of oxygen vacancies produced by ion irradiation. While the irradiation-induced titanium vacancies act as trapping centers for charge carriers and decrease the photoelectrochemical performance of the samples. Positron annihilation spectroscopy (PAS) was used to study the type of the formed vacancies. Combining experimental with theoretical study, this study demonstrates that ion irradiation technique combing with thermal annealing could be an effective way to enhance the performance of photoanode for water splitting.     

一种基于单体泵供油的重型柴油机燃烧系统的开发

采用单体泵供油系统改善喷油特性提高性能是重型柴油机燃烧系统的发展趋势。本研究在现有机型基础上,开发基于单体泵供油的柴油机燃烧系统,通过燃烧系统经验匹配计算,确定了转速、最高燃烧压力、活塞平均速度、进气压力、进气温度以及喷孔方案等参数范围;经过一维性能计算分析,参数选取合理,性能满足指标要求;三维缸内过程仿真分析了两种喷孔方案的喷雾特性、燃烧反应率、放热率等的差异;最后试验验证了燃烧系统匹配是合理的,性能指标实现了大幅度提高。     

Modeling of an anode-supported Ni-YSZ|Ni-ScSZ|ScSZ| LSM-ScSZ multiple layers SOFC cell: Part II. Simulations and discussion

In part I of the present study, a two-dimensional isothermal mechanistic model of a composite yttria/scandia stabilized zirconia anode-supported multiple layers solid oxide fuel cell (Ni-YSZ|Ni-ScSZ|ScSZ|LSM-ScSZ) was developed, calibrated and validated using a button cell setup. In this paper, the model was further validated for extended operating conditions of fuel and oxidant compositions, which confirmed the robustness of the model. Since an important attribute of this model is its ability to accurately describe the effect of cell microstructure on cell performance, a large section of part II is devoted to sensitivity analysis of various microstructure parameters (cathode area, porosity, layer thickness and particle radius) on cell performance. In particular, the simulation results have shown how the button cell microstructure should be modified to optimize its performance. The proposed model could be used as a bridge between micro-scale electrode models and macro-scale unit cell simulation, thus being a useful tool for electrode design.     

Simulation of gas exothermic chemical reaction in porous media reactor with lattice Boltzmann method

Exothermic reactor is the main part in a chemical heat pump. It involves complex multi-component exothermal chemical reaction in catalyst-filled porous media. The lattice Boltzmann method (LBM) is developed to simulate the characteristics of fluid flow, heat and mass transfer coupling chemical reaction in the exothermic reactor of the isopropanol/acetone/hydrogen chemical heat pump system. Fractal theory is used to structure a porous medium model in the reactor. The simulation results show that LBM is suitable for the simulation and the conversion has an optimal value with different inlet velocities.     

增压柴油机排气压力波的对比试验研究

为了对某增压六缸发动机的性能做进一步的改进,对其涡轮入口处和排气支管出口处的排气压力波变化规律进行了试验研究.试验结果表明,涡轮入口处和排气支管出口处的排气压力波平均值变化规律相同:在不同的负荷特性下,排气压力波平均值都随着扭矩的增大而增大;不同转速下相同扭矩测试点的排气压力波平均值,都随着转速的增大而增大.在不同的负荷特性下,涡轮入口处和排气支管出口处的排气压力波强度变化规律不相同,涡轮入口的压力排气波强度要大于排气支管出口处的排气压力波强度.     

Synthesis and characterization of new fluorinated aromatic polyesters containing trifluoromethylphenoxy pendant groups

A series of novel fluorinated aromatic polyesters containing trifluoromethylphenoxy pendant groups was synthesized by interfacial polycondensation of 2‐(4‐trifluoromethylphenoxy)terephthalyl chloride with various bisphenols in dichloromethane. The polyesters obtained in good yields had weight‐average molecular weights of 70,600–29,800 g/mol, polydispersities of 1.81–2.08, and were all amorphous. All polyesters were easily soluble in organic solvents such as N,N‐dimethylformamide, tetrahydrofuran, o‐chlorophenol, pyridine, and dichloromethane. These fluorinated polyesters showed glass transition temperature of 133–210°C, and good thermal stability with almost no weight loss up to 378°C, the 10% weight loss temperature of 472–523°C as well as char yield of 32–63% at 600°C in nitrogen. These polyester films cast from chloroform solutions exhibited tensile strengths ranging from 102 to 126 MPa, elongation at break from 6.3% to 11.7%, and tensile moduli from 2.1 to 3.3 GPa. The resulting polyester films also displayed low dielectric constants between 2.18 and 2.49 (1 MHz), high transparency with an ultraviolet‐visible absorption cut‐off wavelengths in the 332–355 nm range, and excellent electric strengths (50.4–65.6 kV/mm) and volume resistivity (2.51–6.03 × 10¹⁶ Ω cm). © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

新型高聚物复合材料轨枕的成型技术研究

利用废弃高聚物以及化工厂生产磷酸时的副产品废磷石膏为原料,采用双阶挤出机——行星挤出机结合单螺杆挤出机制备新型高聚物复合材料轨枕,研究了复合材料中不同废磷石膏含量对轨枕力学性能的影响;探讨了挤出机转速配比、加工温度、阻尼器设置等工艺参数对材料挤出成型的影响;并且利用ANSYS软件对模具流道冷却进行了模拟分析。     

生物能源研究新进展

主要介绍了燃料乙醇、生物柴油、生物制氢和沼气等生物能源的原料、生产技术及发展现状,探讨了生物能源发展前景。     

聚乙二醇在药物载体应用中的优缺点

聚乙二醇在基于聚合物的药物传递系统中是最常用的高分子同时也是隐形高分子的金标准.从第一个PEG化的产品上市到目前为止,人们获得了大量关于这种聚合物的临床经验-不仪有它的优点,而且也有潜在的副作用以及并发症.文章列举了PEG在生物医药领域应用的一系列优良性质和引起的毒副作用.