Effects of stack array orientation on fuel cell efficiency for auxiliary power unit applications

The commercial fuel cell products currently appearing on the market are self-contained fuel cell engines. These engines can be used for many applications that are presently dominated by internal combustion engines or batteries. Vehicle mounted fuel cell auxiliary power units have been attracting attention lately. Additionally, there is a market based incentive to use multiple small fuel cell arrays in place of a single large fuel cell for some applications. Typically, fuel cells are designed to operate as stand-alone units. This paper investigates the ability of small commercial stacks to operate in common array arrangements. Although an individual Nexa is able to produce 1500 W, Dual Nexas do not maintain that capability while in array configurations. With an overall load share ratio of 1.02:1 the series array reliably produced 2900 W of power, while with an overall load share ratio of 1.09:1 the parallel array reliably produced only 2800 W of power. This study shows that array orientation affects both system stack net efficiency and individual stack net efficiency. The information gained from this study may be helpful for fuel cell design and integration.     

SCREENING A CDNA LIBRARY FOR PHOSPHOLIPASE A2 CLONES USING BLOOD AGAR PLATES

ＳＣＲＥＥＮＩＮＧＡＣＤＮＡＬＩＢＲＡＲＹＦＯＲＰＨＯＳＰＨＯＬＩＰＡＳＥＡ２ＣＬＯＮＥＳＵＳＩＮＧＢＬＯＯＤＡＧＡＲＰＬＡＴＥＳＣｈｅｎＴａｉｐｉｎ；．Ｊ．Ｍｅｚａ，Ｃ．Ｖｉｄａｌ，Ｅ．Ｒａｉｌ（ＤｅｐａｒｔｍｅｎｔｏｆＢｉｏｌｏｇｉｃａｌＳｃｉｅ...     

多源数据融合的城市区域时变停车需求识别方法

城市时变停车需求的准确感知是制定停车管理政策的前提条件之一,然而由于难以获取城市所有停车场进出车辆数据,且部分老旧停车场尚未实现信息化管理,以及违章停车的存在,导致城市区域时变停车需求识别困难。本研究利用城市已有交通信息采集设备,以卡口车牌识别数据、停车场进出车辆数据和出租车GPS数据为基础,通过训练模型区分停车与行车在前后两次卡口数据中的特征差异来识别车辆停车行为,从而实现城市区域时变停车需求识别。首先,结合493个停车场的进出车辆数据和3 649辆出租车的GPS数据确定车辆行停状态,得到846 204个停车样本和81 654个行车样本,并基于合成少数类过采样技术（Synthetic Minority Oversampling Technique,SMOTE）+最近邻（Edited Nearest Neighbor,ENN）算法对不均衡行停数据集进行组合采样;其次,利用梯度提升决策树（Gradient Boosting Decision Tree,GBDT）来识别车辆的停车行为,结果表明本文建立的停车行为识别模型准确率为93.1%,精确率为99.6%,召回率为86.5%,识别效果优于...     

THEORETICAL ANALYSIS OF CHARGE ACCUMULATION ON INSULATOR SURFACE UNDER IMPULSE VOLTAGE IN A GAS INSULATED SWITCHGEAR

Ｉｎｓｕｌａｔｉｎｇｓｐａｃｅｒｓｓｕｐｐｏｒｔｉｎｇｔｈｅｈｉｇｈｖｏｌｔａｇｅｃｏｎｄｕｃｔｏｒｉｎｃｏｍｐｒｅｓｓｅｄｇａｓｉｎｓｕｌａｔｅｄｓｙｓｔｅｍｓｐｌａｙａｎｉｍｐｏｒｔａｎｔｒｏｌｅｉｎｄｅｔｅｒｍｉｎｉｎｇｔｈｅｏｖｅｒａｌｌｓｉｚｅｏｆｇａｓｉｎｓｕｌａｔｅｄｓｗｉｔｃｈｇｅａｒ (ＧＩＳ) .Ｄｕｅｔｏｖｅｒｙｈｉｇｈｓｕｒｆａｃｅｒｅｓｉｔｉｖｉｔｙ ,ｅｌｅｃｔｒｏ ｓｔａｔｉｃｃｈａｒｇｅｓｍａｙｂｅａｃｃｕ ｍｕｌａｔｅｄａｎｄｈｅｌｄａｔｄｉｅｌｅｃｔｒｉｃｉｎｔｅｒｆ…     

集料剪切性能的数值模拟分析

使用微观结构的离散单元模型对集料直剪试验进行数值模拟,以预测集料颗粒的抗剪强度和影响因素．模型用法向和切向刚度等来描述颗粒及接触的本构关系,可通过各参数的调整进行颗粒抗剪强度分析．计算结果表明,微观力学方法评价集料的抗剪强度有较大的分析潜力．     

基于CDIO理念的路桥专业课程体系改革

根据CDIO工程教育理念,结合应用型路桥专业人才培养的特点,探讨了基于CDIO理念的应用型本科路桥专业课程体系和目标体系,并将该理念贯穿在课程内容教学的全过程。运用CDIO教育模式对路桥专业课程的内容、设计进行探讨和实践,在教学中以问题为导向,引导学生主动学习,主动探寻学科知识,促使学生理论与实践的结合能力、创新能力和团队合作能力等有所提高。     

人杀菌渗透增强性蛋白N末端片段在大肠杆菌中的表达

目的构建表达人杀菌渗透增强性蛋白(BPI)N-端193个氨基酸的重组表达质粒,诱导表达BPI193重组蛋白。方法应用RT-PCR的方法从HL-60细胞内扩增出BPI氨基端1-193个氨基酸的基因序列,克隆入T载体。将BPI193基因片段定向克隆入原核表达载体PET-28a中,构建重组的原核表达质粒PET-BPI193,转化大肠杆菌BL21菌株,用IPTG诱导表达蛋白。应用SDS-PAGE检测蛋白表达情况,计算机薄层扫描分析蛋白占菌体总蛋白百分比;Western-blot技术检测表达蛋白的特异性。结果从HL-60细胞中扩增得到579bp的BPI193基因片段,构建了T-BPI193亚克隆和PET-BPI193重组表达质粒。转化大肠杆菌BL21,通过IPTG诱导,经SDS-PAGE检测表明,成功表达了6His-BPI193融合蛋白。计算机薄层扫描分析表达量占菌体总蛋白的12%。Western-blot检测显示表达产物具有特异性。结论成功构建了PET-BPI193重组表达质粒。在大肠杆菌BL21内,诱导获得了BPI193与组氨酸融合表达的重组蛋白。     

基于Petri网建模的机务段管理信息系统的研究与实现

将Petri网建模技术应用于机务段信息化系统的开发过程中,并结合Petri网理论和机务段业务流程的特点,提出了机务段业务流程模型,通过定义的模型5元组来描述各检修过程之间的信息、资源和组织之间的关系,引导过程中的检修活动自动进行,对检修活动所需的资源进行调度分配,从而将各检修活动组织成一个顺畅的工作流程,为机务段业务流程的分析优化以及应用软件系统的开发提供了逻辑模型支持;通过矩阵方程对所建网模型进行性能分析,证明该模型的合理性．该模型能顺应机车检修工艺的变化重组业务流程,实现信息系统的可持续升级．     

The exclusive economic zone: criteria and machinery for the resolution of international conflicts between different users of the EEZ

It is highly probable that one of the results of the Third United Nations Conference on the Law of the Sea will be the recognition of a new jurisdictional zone—the exclusive economic zone (EEZ). This 200-mile zone will be used for a variety of potentially conflicting purposes by both the coastal state and non-coastal states and it is therefore important to ensure that the new convention emerging from the conference should establish criteria and make provision for machinery for the resolution of the international conflicts between different users which will undoubtedly arise. This paper contains a critical analysis of the latest draft articles under consideration at the Conference and considers the criteria by reference to which disputes might be resolved.     

多孔大断面矩形顶管施工的地层变形特征及演化规律

基于随机介质理论,计算多孔矩形顶管隧道施工引起的地层变形,通过实际工程验证计算结果的可靠性,分别讨论单个及多孔大断面矩形隧道施工条件下地层的水平位移、倾斜、曲率以及水平变形的演化规律。研究结果表明：沉降范围和沉降累计最大值均呈线性增大,沉降累计最大值的增幅较大,且4孔时均为单孔的2倍;各地层变形累计最大值均在3号顶管中心附近变化最大,水平位移和倾斜累计值均先增加后减小,变形和曲率累计值均呈线性减小;各相邻顶管中间的扰动区域重叠所产生的扰动效应随管节间距和尺寸的变化而变化。