温控负荷不确定时滞下微网电压稳定鲁棒控制

针对温控负荷的不确定时滞特性对微网电压稳定的影响,提出基于T-S模糊模型的微网电压稳定鲁棒控制方法。在微网温控负荷不确定时滞特性建模研究的基础上,建立电压稳定T-S模糊系统控制模型,并设计微网无功模糊反馈控制器,使得系统在无外部干扰条件下,通过无功调节保持电压稳定性。基于电压稳定T-S模型,研究考虑微网内其他负荷的突然增减或动力设备的起停等外部扰动下的电压稳定机理,建立微网电压稳定性H∞鲁棒控制方法。研究改进后的三机九节点微网温控负荷不确定时滞仿真系统模型,通过算例仿真,对提出的电压稳定控制方法进行验证。仿真结果表明,基于T-S模糊模型的温控负荷不确定时滞下的H∞鲁棒控制能有效提高微网电压稳定性能。     

风电出力不确定时滞扰动下送端电网功角稳定鲁棒最优控制

针对考虑风电波动不确定性的送端电网功角稳定问题,研究了线性送端电网功角稳定的不确定时滞系统模型及其优化控制目标函数;建立了不考虑系统不确定性的鲁棒优化控制策略;提出了基于滑模控制的不确定性时滞系统鲁棒控制策略。通过单机-无穷大系统模型,对风电送端电网功角稳定控制模型进行了仿真,验证了模型的有效性。     

基于粘结滑移的衬砌裂缝宽度计算模型研究

基于粘结滑移理论提出了一种“实体单元-影子节点-梁单元”的传力体系。以某一模型试验为例,将钢筋混凝土衬砌采用分离式建模并构建此传力体系。通过有限元计算求得受力钢筋的应力,结合规范的计算公式求出裂缝的最大宽度。与试验结果进行对比,验证了有限元建模运用此传力体系并结合规范公式计算最大裂缝宽度的可行性,可为同类工程最大裂缝宽度提供一种新的计算方法。     

The effect of cation-anion difference on calcium requirement, feed intake, body weight gain, and blood gasses and mineral concentrations of dairy calves

Our objective was to examine the effects of two diets with different cation-anion differences on Ca requirements in the growing calf. Holstein calves (n = 48, 24 males) were blocked at 56 to 70 d after birth (80+/-10 kg of body weight) according to sex and birth date and assigned randomly in a 2 x 3 factorial arrangement of dietary treatments containing cation-anion differences as meq (Na + K) - (Cl + S)/kg of diet dry matter and Ca content of 1) 0 and 0.35%, 2) 0 and 0.50%, 3) 0 and 0.65%, 4) 200 and 0.35%, 5) 200 and 0.50%, and 6) 200 and 0.65%. Feed intake and average daily gain did not differ among treatment groups. Plasma pH and Ca were unaffected by dietary Ca content or dietary cation-anion difference. Plasma Cl and P decreased linearly with increasing Ca content in the diet. Plasma HCO3 increased linearly with increased dietary Ca content. Plasma HCO3 and partial pressure of CO2 were higher in calves fed the 200 compared with calves fed the 0 cation-anion difference diets. Plasma Cl was, however, lower in calves fed the 200 compared with calves fed the 0 meq diets. An interaction of Ca content and dietary cation-anion difference was detected for plasma P content. Urinary pH increased linearly with increasing dietary Ca content. Calves fed the 200 meq dietary cation-anion difference had higher urinary pH values than those fed the 0 meq diet. Urinary P excretion was not altered by dietary cation-anion difference or Ca content of the diet. Calves fed the 0 meq diet had higher urinary cocnentrations of Ca and Cl when compared with those fed the 200 meq diet. Bone ash, P, Ca, Mg, and K content of the 10th rib were not affected by dietary treatments. Breaking strength of the seventh and ninth ribs increased quadratically with increasing dietary Ca content. Dietary cation-anion difference had no effect on the breaking strength of the seventh and ninth ribs. Varying the dietary cation-anion difference from 0 to 200 meq/kg of dietary dry matter had no effect on Ca requirement of the growing calf.     

PV材料市场将获得爆炸式成长

随着世界上一些特选地区的光伏能源接近电网平价,及电池制造业的努力以进一步降低成本,PV产业正成为并网电力的一个非常重要的选择。根据Linx Consulting(Mendon,Mass.)的最新报告,PV产业的成长反映在光伏组件制造材料市场上的影响是,在今后几年该市场将如流星焰火般猛涨。     

巴卡花园

WAA受邀为巴卡的一个家庭设计花园，该项目所在的地段是耶路撒冷最冷最有发展前景的街区。     

激增的需求推动晶圆清洗技术的发展

更小、更脆的结构及新材料的主导地位,对清洗技术提出了更高的要求,在技术解决方案上需要更多结合使用各种方法,包括湿法和干法技术、机械和化学处理。     

基于加窗隐马尔可夫模型的窄带干扰抑制技术研究

针对基于隐马尔可夫模型的窄带干扰抑制技术在直接序列扩频系统中存在频谱泄漏和收敛速度较慢的问题,提出增加窗函数并选择合适的HMM训练估计时隙数的改进算法,该方法在减弱"频谱泄漏"效应的同时,加快了算法的收敛速度.仿真实验表明改进算法对快变的强窄带干扰具有较好的抑制效果.     

低碳经济对国际贸易规则的影响及中国对策研究

基于经济全球化的背景,低碳经济开始被世界各国所关注.世界各国在发展经济的同时,都开始强调绿色及环保发展.只有将经济发展同生态发展达成一致,才能促进各国的持续及稳定发展.基于此,本文首先简单介绍了低碳经济,接着就国际贸易的影响进行了分析,其中包括政策影响、产业链影响、国际标准化组织影响,最后在此基础上提出了几点中国的应对...     

半导体掺杂剂的现状

半导体所使用的掺杂剂在固相、液相和气相等所有物相中是比较丰富的;所用的特殊的掺杂剂类型取决于设备、有利条件和安全系数。