考虑输配电价改革的省级电网规划投资效率效益评估

输配电价改革对于省级电网前端规划提出了更高要求。基于输配电价改革要求,构建省级电网不同类型规划投资项目单位产出效率效益指数模型,并综合考虑历史规划项目优选的叠加影响、各类项目相对重要度和规划目标约束,构建基于效率效益指数模型的省级电网投资分配和优选模型,基于风险指数模型剖析影响效率效益指数的关键不确定性指标。通过与传统方法及输配电价核心监管参数进行比较,验证了方法的有效性。结果表明,提出的方法在新形势下评估各类项目效率效益合理性方面优于传统方法,且电量、资产是电网投资效率效益指数主要影响指标,与输配电价监管核心参数一致,此外,电网公司应重点关注满足新增负荷、加强网架和变电站配套送出类项目。     

3种泵轴倾角斜式进水流道水力性能的比较

采用三维湍流流动数值计算的方法,对泵轴倾角为15°、30°和45°的3种斜式进水流道的水力性能分别进行了较为深入的研究,并对3种泵轴倾角的斜式进水流道分别进行了流道模型试验研究.结果表明:3种泵轴倾角斜式进水流道内的流态平顺均匀、水力损失小、水力性能优异,可为水泵叶轮室进口提供近乎理想的流态;斜式进水流道出口的目标函数...     

多媒体计算机技术及其发展前景

多媒体(Multimedia Syctem)是一个集声音、图像与文本为一体的多功能计算机系统,近年来多媒体技术巳成为国内外计算机界普遍关注的课题。本文介绍了多媒体技术的概念,技术特点及其发展前景。     

Surfactant interactions with P(AM–AA–BPAM) hydrophobically modified polyelectrolytes

The interactions of hydrophobically modified polyelectrolytes poly(acrylamide–sodium acrylic acid–N‐(4‐butyl)phenylacrylamide [P(AM‐AA‐BPAM)] with anionic (sodium dodecyl sulfate), cationic (cetyl trimethylammonium bromide), and nonionic (tetradecyldimethyl‐aminoxid) surfactants were studied via solution rheology, surface tension, and atomic force microscopy measurements. Viscosity measurements indicated that the intermolecular association of the polymer was greatly enhanced by the interaction with the surfactants, especially the oppositely charged surfactants with both a hydrophobic association and an electrostatic attraction. The greatest viscosity increase was realized with the addition of such oppositely charged surfactants. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 2664–2671, 2003     

Effects of random chopped short carbon fibers on microstructure and mechanical properties of joints for Cf/SiC composites by reaction bonding process

Random chopped short carbon fibers (C_sf)/phenol-formaldehyde resin (PF)/SiC powder mixtures are used as filler for the joining of C_f/SiC composites to obtain SiC interlayer at the joining region. The influences of C_sf on the microstructure and mechanical properties have been investigated. Research shows that the introduction of C_sf can improve the microstructure uniformity of the joint and reduce residual silicon content in the interlayer. The joint achieve a high flexural strength of 232?±?33?MPa as the carbon fiber content is 30?wt.%, which is similar to that of the C_f/SiC composites (220?±?21?MPa). The decrease in residual silicon content and the formation of nano-sized SiC particles are the main reasons for high joining strength.     

煤气初冷器余热回收新技术

开发了初冷器余热回收利用新技术。通过热泵机组,夏季回收初冷器上段循环水余热制取低温水,冬季回收初冷器中段循环水余热加热采暖水,实现了初冷器余热的综合利用,降低了能耗,改善了环境。     

Preparation and characterization of chitosan/poly(vinyl alcohol) blend fibers

Chitosan and poly(vinyl alcohol) blend fibers were prepared by spinning their solution through a viscose‐type spinneret at 25°C into a coagulating bath containing aqueous NaOH and ethanol. The influence of coagulation solution composition on the spinning performance was discussed, and the intermolecular interactions of blend fibers were studied by infrared analysis (IR), X‐ray diffraction (XRD), and scanning electron micrograph (SEM) and by measurements of mechanical properties and water‐retention properties. The results demonstrated that the water‐retention properties and mechanical properties of the blend fibers increase due to the presence of PVA in the chitosan substract, and the mechanical strength of the blends is also related to PVA content and the degree of deacetylation of chitosan. The best mechanical strength values of the blend fibers, 1.82 cN/d (dry state) and 0.81 cN/d (wet state), were obtained when PVA content was 20 wt % and the degree of deacetylation of chitosan was 90.2%. The strength of the blend fibers, especially wet tenacity could be improved further by crosslinking with glutaraldehyde. The water‐retention values (WRV) of the blend fibers were between 170 and 241%, obviously higher than pure chitosan fiber (120%). The structure analysis indicated that there are strong interaction and good miscibility between chitosan and poly(vinyl alcohol) molecular resulted from intermolecular hydrogen bonds. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 2558–2565, 2001     

一起500kV变压器内部放电故障的检测与分析

变压器内部局部放电故障因具有潜伏时间长、放电信号微弱等特点,运行过程中难以开展有效的检测,因此严重威胁变压器的安全运行。针对某变电站一台500k V变压器油中乙炔气体超标故障,结合油色谱分析,应用红外测温、超声波局放检测等多种带电检测手段,并根据红外图谱及多种模式下的局放检测波形,通过专家会诊及运用模式识别等故障诊断方法,得出变压器内部磁屏蔽接地不良而导致对外壳放电的结论。最后,提出了故障的处理过程以及预防性措施,对现场实际具有较大的指导意义。     

职业能力为导向的高职计算机网络技术专业建设

信息产业的发展使网络技术的应用越来越广,已渗透到我们生活的方方面面,培养具有综合专业技能的实用型计算机网络技术人才已成为信息社会的迫切需要。本文以江西经济管理职业学院计算机网络技术专业为例从课程建设、师资建设和实训室建设等方面谈谈高职院校中网络专业的建设。     

基于修正θ投影法的GH4169高温合金蠕变寿命预测

在不同温度和不同应力条件下,对GH4169高温合金进行了蠕变实验,得到不同参数下的蠕变数据并绘制了相应的蠕变寿命曲线。利用修正θ投影法,对得到的实验寿命曲线进行非线性拟合,建立了温度、应力相关的蠕变方程。用所建立的蠕变方程验证了GH4169高温合金蠕变寿命曲线,结果表明吻合性较好,达到了蠕变寿命预测的效果。