兆瓦级风电变流器IGBT模块的热特性分析

以某企业建立的采用液冷冷却系统的IGBT模块实验平台为基础,对一3MW紧凑型风电机组的IGBT模块的热特性进行了分析.根据在动态实验中采集到的数据,得出了逆变器输出功率与时间的关系,并结合实验数据对模块温度以及发热量的变化特性进行了分析,得到了兆瓦级风电变流器中IGBT模块温度与发热量随时间的变化关系.实测结果表明,该风电机组逆变器的效率为98.62%,IGBT模块的最终工作温度保持在50~56℃,说明采用的液冷冷却系统对大功率IGBT模块具有良好的冷却效果.     

光化学沉积法制备Ag掺杂SnZn(OH)_6空心粒子及其光催化性能

采用均匀沉淀法制备了具有立方相的Sn Zn(OH)6(ZHS)空心粒子,然后通过光化学沉积法将Ag+还原为Ag0粒子负载于其上,制备得到负载Ag纳米粒子的Sn Zn(OH)6粒子;使用X射线衍射(XRD)、扫描电镜(SEM)、紫外-可见漫反射(DRS)等方法对产品进行了表征,并对其在紫外及可见光下降解罗丹明B的光催化活性进行了检测.结果表明,负载金属银粒子的ZHS不仅在紫外光下对罗丹明B的降解能力有显著的提高,而且对可见光也有明显的响应.     

SCI收录的病理学期刊的文献计量分析及投稿选刊策略

以SCI期刊引证报告（JCR）最新网络版（2013年）为依据,结合Med Sci平台,采集了76种病理学期刊的影响因子、国别、语种、出版频率、学科分区、即年指标、被引半衰期、Med Sci指数等指标,检索并计算出近5年各期刊刊载中国论文的比例,分析了SCI收录的病理学期刊的文献计量学特征,为专业人员投稿选刊提供了参考。     

Assessment of alternated cooling and heating treatment by US combined CEUS in the VX2 rabbit liver tumor model

Inoperable liver tumors are often treated by thermal ablation that destroys the tumor in situ and spares the adjacent hepatic tissue.Thermal–physical treatment has many advantages,but treatment by freezing or heating alone has some limitations.By taking the advantages and disadvantages of cryosurgery and thermotherapy into consideration,a new thermal technique that combines cryosurgery and radio frequency ablation has been proposed,thereby overcoming the disadvantages of each treatment strategy and improving therapeutic outcomes.This new approach remains to be systematically studied in the liver;therefore,this study was performed to estimate survival after alternated cooling and heating ablation therapy in a VX2 rabbit liver tumor model.Sixteen days after VX2 carcinoma implantation into the rabbit liver,tumors were treated with alternated cooling and heating ablation therapy.Rabbits were monitored for 6 months after treatment and assessed with ultrasound(US)and computed tomography at 1,7,14,and 30 days posttreatment.Untreated tumor-bearing animals served as the control group.Our results show that alternate freezing and heating ablation therapy resulted in a good recovery of VX2 rabbits.Compared with the control group,treated rabbits lived significantly longer(P\0.05),with 70%of treated animals surviving to 196 days posttreatment without metastasis or recurrence,while none of the controls did so.There was no local recurrence in the treatment group.All rabbits in the control group developed metastasis,while metastasis was only observed in 30% of treated rabbits.These results suggest that alternate cooling and heating ablation therapy can prolong the survival time of rabbits with VX2 liver tumors and is an effective method for tumor therapy.Furthermore,we also showed in this model that contrast enhanced US is a valid follow-up approach to assess treatment effectiveness.     

On Peer-Assisted Data Dissemination in Data Center Networks: Analysis and Implementation简

Data Center Networks （DCNs） are the fundamental infrastructure for cloud computing. Driven by the massive parallel computing tasks in cloud computing, one-to-many data dissemination becomes one of the most important traffic patterns in DCNs. Many architectures and protocols are proposed to meet this demand. However, these proposals either require complicated configurations on switches and servers, or cannot deliver an optimal performance. In this paper, we propose the peer-assisted data dissemination for DCNs. This approach utilizes the rich physical connections with high bandwidths and mutli-path connections, to facilitate efficient one-to-many data dissemination. We prove that an optimal P2P data dissemination schedule exists for FatTree, a specially- designed DCN architecture. We then present a theoretical analysis of this algorithm in the general multi-rooted tree topology, a widely-used DCN architecture. Additionally, we explore the performance of an intuitive line structure for data dissemination. Our analysis and experimental results prove that this simple structure is able to produce a comparable performance to the optimal algorithm. Since DCN applications heavily rely on virtualization to achieve optimal resource sharing, we present a general implementation method for the proposed algorithms, which aims to mitigate the impact of the potentially-high churn rate of the virtual machines.     

密封皮碗骨架结构改进及优化分析

针对钻井作业中密封皮碗在高压下失效的现象,设计了一种密封皮碗的钢制骨架。应用ANSYS Workbench,通过建立具有钢质骨架的密封皮碗模型,进行35MPa密封压力下的承压能力分析;通过对骨架结构相关参数进行优化设计,得到满足设计要求的密封皮碗骨架形式。     

基于职业锚理论的女性图书馆员职业生涯发展研究

随着对职业生涯规划重视度的增加,职业锚理论越来越受到各行各业的推崇和重视。结合女性馆员的职业发展情况,分析了我国女性馆员职业生涯发展面临的问题及其影响因素,提出了将职业锚理论应用于图书馆的具体措施和建议。     

低频激励的煤体瓦斯解吸试验

针对一些地区煤矿瓦斯赋存浓度高,不能采用外加电磁场的方式促进瓦斯的解吸问题.利用自制的低频激励瓦斯解吸及测量装置,设置了3组实验,通过测量不同情况下煤样罐中瓦斯的解吸量,研究低频振动和声波(统称为低频激励)对瓦斯解吸的综合影响.结果表明:低频激励条件下瓦斯解吸量是自然条件下的2倍左右,施加频率为70~120 Hz,激励的煤样罐比其他煤样罐中每100 g煤样剩余瓦斯量少.试验结果证明了低频激励可以加快瓦斯解吸速率,加深瓦斯解吸程度.激励的频率在70~120 Hz变化时,由于达到了瓦斯附着的本振频率而使瓦斯解吸程度加深.另外试验还间接证明了声波对瓦斯解吸有积极的作用.     

A novel GEL-OHA/HAp bone substitute

Self-crosslinked gelatin-oxidized hyaluronic acid/ hydroxyapatite (GEL-OHA/HAp) composite bone substitute was successfully prepared with a novel in situ precipitation method without using any toxic chemical cross-linkers, and its characterizations, including elemental composition, surface morphology, crystallinity, and structure of crystalline phase, were carried out. In order to evaluate its corresponding performances, comparisons with glutaraldehyde crosslinked gelatin/hydroxyapatite (GEL-Glu/ HAp) composite were made in detail. The results indicate that nano-HAp crystallites are homogeneously dispersed in both GEL-OHA/HAp and GEL-Glu/HAp composites, and the HAp crystallites in the former take larger particle size than those in the latter. Mechanical property tests show the acceptable mechanical strength at high strain of GEL-OHA/HAp composite. Study of in vitro degradation and swelling demonstrate that the two composites have similar degradation rate and water absorption capability. By in vitro cell culture, it has been found out that the cells on the GEL-OHA/HAp composite show higher proliferative potential than the cells on the GEL-Glu/HAp composite. Compared with GEL-Glu/HAp composite, GEL-OHA/HAp composite provides an excellent strategy for preparation of non-toxic bone substitute with acceptable corresponding properties.