基于MMC的柔性直流输电站级控制器的设计及其动模实验

站级控制器是模块化多电平换流器柔性直流输电控制系统的核心部分,与上位机、下层控制器协同配合实现柔性直流输电的可靠控制。对基于MMC-HVDC站级控制器主要功能进行了分析,提出了一种站级控制器硬件结构设计方案,并针对该硬件结构以及功能需求设计了软件程序逻辑。研制了基于该站级控制器的4kV/100kW的MMC-HVDC实验样机,在样机上进行稳态实验以及电压阶跃实验,结果表明系统能够正确快速进行有功类无功类物理量的调节,并能对交流系统故障以及控制器通信故障进行清除,验证了站级控制器硬件结构及程序逻辑的正确性。     

亚甲基[6,6]-Fullerene[C60]单羧酸衍生物的合成

以溴乙酸乙酯、硫醚和Fullerene[60]为原料合成Fullerene[60]羧酸乙酯,再经水解、酸化得到亚甲基[6,6]-Fullerene[C60]单羧酸,并进一步反应得其酰胺。这些新化合物的结构经IR和1HNMR确证。     

邻苯二甲酸二烯丙基酯树脂固化特性的研究

运用示差扫描量热(DSC)法研究了邻苯二甲酸二烯丙基酯(DAP)树脂的固化反应历程。讨论了引发剂对DAP固化特性的影响,并由DSC曲线得到了DAP树脂的固化工艺和动力学参数。通过固化度、FT-IR的测试对DAP树脂在中温条件下的固化情况进行了研究。结果表明:在过氧化二异丙苯(DCP)固化体系中引入BPO可以使DAP树脂在更低温度下引发固化;在BPO、DCP用量均为2%的条件下,确定了体系的凝胶温度、固化温度、后处理温度分别为:100.5℃,124.3℃,137.8℃,表观活化能为129.3 kJ/mol,反应级数为0.950。固化度、FTIR的测试结果表明:DAP树脂在中温条件下可以固化得较完全。     

液压施肥技术应用于大树复壮

2005年,针对区域绿化养护迫切需要改革的现状,由我局牵头组织调研;重点分析了土壤和植物的现状,选择了上海汉枫缓释肥料有限公司的缓释肥料技术及专有的液压注射施肥技术进行试点。经过2年的实践,证实了液压注射施肥技术对于大树复壮具有良好的效果,为行道树和绿地大型乔木的复壮和土壤改良提供了成熟的施肥新技术,提高了绿化养护作业的科技含量。     

太湖清淤底泥离心脱水处理技术的可行性研究

研究了卧螺离心机在太湖生态清淤工程应用中的脱水性能及可行性。分别对含水率97.5%和84.6%的生态清淤底泥进行脱水处理,实现了淤泥快速泥水分离。探讨了离心机转鼓转速、差转速,絮凝剂投加量、加药位置、液环层厚度、工作压力等工艺参数对淤泥脱水效果的影响。应用结果表明,离心脱水技术处理清淤底泥具有良好的实际效果和应用推广价值。     

电压比值差相位差对电能计量装置误差的影响

电压参数比值差、相位差是电能计量装置中引起电能计量误差的关键因素之一,通过电路分析和数学推导对电能计量相对误差εr与比值差f、相位差δ之间的关系进行分析.结果表明,f、δ是电压信号采集环节εr产生的直接原因;其中f与εr直接相关,δ通过tanφ与εr间接相关;f、δ、tanφ共同对εr数值产生影响.     

Essential oil composition and antimicrobial activity of Sphallerocarpus gracilis seeds against selected food-related bacteria

Sphallerocarpus gracilis from China is a little-investigated edible and medicinal plant. In the present study, the essential oil composition from S. gracilis seeds was investigated by GC and GC–MS. A total of 34 compounds representing 94.69% of the essential oil were tentatively identified. The main constituents were p-cymene (17.42%), γ-terpinene (25.58%) and α-asarone (33.12%). The antimicrobial activity, minimum inhibitory concentration (MIC), and minimum bactericidal concentration (MBC) of the essential oil from S. gracilis seeds were evaluated against eight Gram-positive bacteria (Listeria monocytogenes, Staphylococcus aureus, Staphylococcus epidermidis, Micrococcus luteus, Bacillus megaterium, Bacillus cereus, Bacillus coagulans and Bacillus subtilis), four Gram-negative bacteria (Salmonella enteritidis, Salmonella typhimurium, Klebsiella pneumoniae and Escherichia coli) and one fungus (Aspergillus niger). Results revealed that the essential oil from S. gracilis seeds exhibited significant in vitro antimicrobial property. Among all the tested microorganisms, the essential oil showed the strongest inhibitory effect against K. pneumoniae, whereas no inhibitory effect was found against L. monocytogenes and A. niger. Additionally, scanning electron microscopy (SEM) was used to observe morphological changes of bacteria treated with the essential oil from S. gracilis seeds. SEM observations confirmed the physical damage and considerable morphological alteration to the tested microorganisms treated with the essential oil. The data of this study suggests that the essential oil from S. gracilis seeds has great potential for application as a natural antimicrobial agent to preserve food.     

HULL GESTURE AND RESISTANCE PREDICTION OF HIGH-SPEED VESSELS

Since trim and sinkage are significant while vessels are advancing forward with high speed, the predicted vessel resistance based on restrained model theory or experiment may not be real resistance of vessels during voyage. It is necessary to take the influence of hull gesture into account for oredicting the resistance of high-speed ship. In the present work the resistance problem of high speed ship is treated with the viscous flow theory, and the dynamic mesh technique is adopted to coincide with variation of hull gesture of high speed vessel on voyage. The simulation of the models of S60 ship and a trimaran moving in towing tank with high speed are conducted by using the above theory and technique. The corresponding numerical results are in good agreement with the experimental data. It indicates that the resistance prediction for high speed vessels should take hull gesture into consideration and the dynamic mesh method proposed here is effective in calculating the resistance of high speed vessels.     

关于纵火罪的新界定及意义

从火灾构成因素分析纵火罪,科学全面地界定纵火罪及相关罪名,对实际裁判和火灾勘查有重要意义。     

英国的绿带政策及对我国城市绿带建设的启示

本文简要回顾了英国绿带政策从早期探索到发展成熟的历程,对围绕其进行的总结与反思的研究成果进行了归类总结,指出了其最新的研究趋向。在此基础上对我国目前绿带政策的制定与实施提出建议。