Effect of interfacial friction force on material removal in full aperture continuous polishing process

Full aperture continuous polishing using pitch lap is a key process of finishing large flat optical workpiece. The friction force of the workpiece and pitch lap interface significantly affects material removal. In this work, the friction force was determined by a measurement system that uses force transducers to support the workpiece. Experimental and theoretical analyses have been carried out to investigate the evolution of friction force with polishing time and its effect on material removal. Our results show that the friction coefficient of the workpiece/lap interface decreases during polishing, which is due to surface smoothing of the viscoelastic pitch lap by loading conditioner. In addition, the spatial average and uniformity of material removal rate (removal coefficient) increases with the increase of friction coefficient, which is due to rough lap surface, provides more sharp asperities to charge the polishing particles.     

DMSO辅助浓缩气相色谱-质谱联用仪测定水产品中6种丁香酚类化合物

建立了水产品中6种丁香酚类化合物的二甲亚砜(DMSO)辅助浓缩-气相色谱-质谱联用仪(GC-MS)测定方法。试样加入无水硫酸钠后,以乙腈为提取溶剂,乙腈饱和的正己烷脱脂,乙腈层加入二甲亚砜(DMSO)辅助氮吹浓缩至近干;采用DB-1701色谱柱进行分离,并用质谱进行检测。6种化合物在20~1000 μg/L内呈良好的线性关系(相关系数大于0.999);在四种基质中的加标水平分别为0.02、0.04、0.10 mg/kg时,6种化合物平均加标回收率为64.8%~110.9%,相对标准偏差均不大于15%(n=6);方法定量限为0.02 mg/kg。该方法灵敏、准确度高、快速、线性范围宽、选择性好、前处理简单,并解决了目前文献方法中仅直接氮吹浓缩对回收率影响很大的关键问题,适用于水产品中丁香酚类化合物的准确定性定量检测,可用于水产品中该类麻醉剂的摸底监测。     

Multi-period wind integrated optimal dispatch using series PSO-DE with time-varying Gaussian membership function based fuzzy selection

Wind power has emerged as the most promising option for providing sustainable eco-friendly power supply to the modern world. Due to its unpredictable nature, integration of wind power into the conventional power grid is a very challenging task having dynamic characteristics. Due to the inherent uncertainty associated with wind availability, additional spinning reserve needs to be scheduled in order to maintain security and supply reliability. Multi-period multi-objective optimal dispatch (MPMOOD) is presented for wind integrated power system with reserve constraints. The complex relationship between wind power availability, spinning reserve allocation and their impact on economic/environmental cost are analysed using an elaborate model.A new multi-objective Series PSO-DE (SPSO-DE) hybrid algorithm is proposed where the two paradigms, differential evolution (DE) and particle swarm optimization (PSO) share domain information and maintain a synergistic cooperation to overcome their individual weaknesses. For multi-objective (MO) problems, the selection operation in SPSO-DE is replaced by a 5-class time-varying fuzzy selection mechanism (TVFSM) to avoid saturation and to increase Pareto diversity. To promote convergence towards the central part of the Pareto front and to quickly isolate the boundary solutions, Guassian membership function is employed. Elitism is applied to preserve good solutions and momentum operation is used to stop premature convergence. The proposed method expedites the search for the best solution, i.e. the solution which satisfies all the objectives of the MO problems. To test the performance and computational efficiency, the proposed method is applied on two standard test power systems.     

左西孟旦在心脏外科术后重症患者的应用研究

目的：研究左西孟旦对重症心脏外科术后患者心功能、肺高压、肾功能等方面的影响。方法：选取2014年1月－2019年6月在宁波市医疗中心李惠利医院胸外科接受心脏手术治疗的重症患者320例，采用随机数字表法将患者分为实验组和对照组，各160例。根据患者具体病情选择心脏换瓣手术或非体外循环搭桥手术，实验组围术期同时给予左西孟旦治疗。比较2组患者手术前后不同时间心、肾功能指标水平及肺动脉收缩压（PASP）变化。结果：术后24 h 2组患者心率（HR）、平均动脉压（MAP）、中心静脉压（CVP）比较无明显差异，实验组血乳酸（LAC）在术后12 h及术后24 h明显低于对照组（P<0.05或P<0.01）；术后1～14 d 2组左室舒张末期容积（LVEDV）、收缩末期容积（LVESV）均呈减小趋势，且同一时间点实验组明显小于对照组（P<0.05或P<0.01）；2组心脏指数（CI）及左室射血指数（LVEF）均呈升高趋势，且同一时间点实验组明显高于对照组（P<0.01）。术后3～14 d 2组血浆N末端前脑利钠肽（NT-proBNP）水平及PASP均呈降低趋势，且同一时间点实验组明显低于对照组（P<0.05或P<0.01）；实验组血清尿素氮（BUN）、24 h尿蛋白定量（24Upro）及血肌酐（Scr）水平均无明显变化（P>0.05），对照组血清BUN、24Upro及Scr水平先升高后降低，且同一时间点实验组明显低于对照组（P<0.05或P<0.01）。与对照组比较，实验组术后死亡率、ICU住院时间、呼吸机及主动脉球囊反搏（IABP）支持时间均明显低于对照组（P<0.05）。结论：心脏手术后给予左西孟旦可有效改善重症患者术后心功能，保护由于低灌注引起的肾损伤，且可降低术后早期肺动脉高压的发生，值得临床借鉴。     

复合地基处理技术研究现状及展望

阐述了复合地基的研究现状,通过对复合地基理论研究的综合述评,论述了各种类型复合地基的标准化情况,分析了复合地基中的一些问题.提出了今后需要开展的研究工作.     

重晶石防辐射泵送混凝土的制备与应用重晶石防辐射泵送混凝土的制备与应用

以普通硅酸盐水泥为胶结料,重晶石、重晶砂、河砂为集料,添加粉煤灰及外加剂,调整投料顺序,采用强制式搅拌机,制备重晶石防辐射混凝土,并采用泵送方式浇注,性能达到设计要求,并在工程中成功应用.介绍原材料、配合比、生产工艺、产品性能、生产控制及使用中应注意的事项.     

基于GIS的机动雷达部署系统研究与实现

针对传统机动雷达的部署面临阵地选择时间长,不具有直观性,缺乏详细地理信息的不足,设计并实现了一种基于GIS的机动雷达部署系统,实现了机动雷达的优化部署。仿真结果表明,此系统对机动雷达部署具有一定的指导意义和实际应用价值。     

开窗压制干扰下的目标跟踪方法

针对开窗干扰隐蔽性强,目标检测概率低的特点,文中提出了利用接收机检测门限判断干扰的方法以及基于TOMHT的目标跟踪方法,同时研究了不同雷达探测区域内目标的航迹管理。仿真表明,此方法具有较强的适应性,实现了开窗干扰下的目标跟踪,对开窗干扰下目标跟踪具有一定的理论参考意义和实际应用价值。     

宁波地区基于统计升尺度的新能源区域功率预测算法

为实现电网调度对大规模风电场和光伏站的监控和调度,需要进行新能源区域功率预测。提出了一种基于子区域划分和统计升尺度的区域功率预测算法,通过浙江区域9个风电场和16个光伏站2016年4-9月的历史数据,对比了6种不同的组合方案,发现利用互信息理论,基于最大相关–最小冗余原则累加选取4个代表站点或者直接选取9个代表站点,采用布谷鸟搜索算法训练得到各个代表站点的权重,升尺度得到区域功率预测误差较低,月均方根误差(RMSE)分别为8.51%和7.64%。说明在夏季风盛行时,在浙江区域采用互信息为指标,基于最大相关–最小冗余的原则选取代表站点后,再采用布谷鸟搜索算法得到子区域功率预测值,累加各子区域功率预测结果为最终的区域功率预测结果最优。     

环境温度对CVT计量误差的影响

电容式电压互感器(CVT)的计量精度易受到多种环境因素的影响,其中环境温度为主要的影响因素。温度变化会引起CVT电容分压单元的电容量与介质损耗因数发生改变,从而影响CVT的计量精度。采用仿真与试验相结合的方式研究了温度对220 kV CVT计量误差特性的影响规律。仿真和试验结果表明随着环境温度升高,CVT电容分压单元高、低压臂电容的电容量呈减小趋势,介质损耗因数呈先减小后增大的变化趋势。环境温度的升高会导致CVT的比差负向增大,角差正向增大。在温差大的地区,若CVT存在较大的初始误差,环境温度的变化将导致CVT存在超差的风险。