半导体照明中结温的电学法测试与优化

基于电学法测试半导体照明的结温,实现了结温测试的电路,采用脉冲调制对LED的瞬态结温值进行测试.实脸发现,结温与正向电压的标定系数K值是影响结温测试精度的主要因素,分析了产生误差的主要原因,并对该系数进行修正.测试结果表明:结温的实测值与参考值有良好的一致性,存在误差的原因是采样的延时时间较长,可提高数据采样率和剔除不...     

A goodness-of-fit test for Archimedean copula models in the presence of right censoring

A goodness-of-fit testing procedure for Archimedean copula (AC) models is developed based on right-censored data. The proposed approach extends an existing method, which is suitable for the Clayton model, to general AC models. Asymptotic properties of the proposed test statistics under the true model assumption are derived. Simulation analysis shows that the proposed test has reasonable performance. Finally, two real data examples are analyzed for illustrative purposes.     

Sensitivity analysis of important parameters affecting contact pressure between a respirator and a headform

Respirator comfort and fit are two important parameters for respirator design, usage, and standard development. The contact pressure (as measured between a respirator and the wearer) plays an important role in comfort and fit. This work attempts to investigate the contact mechanism and factors that affect the contact pressure. This paper focuses on mechanical factors such as strap tension, strap orientation, strap location, friction, and seal material. A finite element (FE) model-based method was developed to assess the contact pressure. The FE models for both the headform and the respirator have multiple layers. The headform is a medium size headform developed by the National Institute for Occupational Safety and Health (NIOSH) and the respirator is an MSA Affinity Ultra respirator. The results show that the positive Z directional force of strap tension that forces the respirator to move towards the headform is the most important parameter for measuring pressure distribution. Other factors such as strap orientation, friction, strap location, and softness of the seal material were found to affect the contact pressure distribution in this study. Strap orientation and friction coefficient have no significant effect on maximum pressure and maximum shear stress. The dispersive strap location increased the contact pressure on the nose-bridge area of the wearer, while concentrated location had no considerable effect on contact pressure. A softer seal material causes larger deformations and transfers the location of the maximum pressure from the nose-bridge to the tip of the nose.

Relevance to industry

This study investigates the effect of important parameters on contact pressure between a respirator and a headform. The sensitivity analysis can provide insights of the interaction between a respirator and a headform. The findings are critical to respirator designers, users, and standard developers to ensure maximal respirator fit and comfort.     

紧密衔接工序组联动的综合调度算法

由于现有的工序间存在紧密衔接条件的复杂产品综合调度问题, 采用的移动交换算法不易于软件实现且没有考虑移动工序后产生的连锁反应引起较高算法复杂度的问题, 提出将具有紧密衔接约束条件的工序组进行统一联动的综合调度算法.该算法利用将具有紧密衔接约束条件的工序分组的扩展加工工艺树模型, 按路径上属于工序组的工序个数多少确定所在路径工序组调度的次序, 通过降低对工序组的限制要求降低算法复杂度; 对于被调度工序组中各工序的前序工序, 按工序组中工序的加工顺序确定调度次序, 对某个工序的前序工序采用复杂度较低的拟关键路径法确定工序的调度次序; 调度完所有紧密衔接工序组后, 剩余的标准工序按拟关键路径法确定调度顺序; 采取工序首次适应调度算法调度标准工序和工序组, 由于工序组中工序采取按序紧密衔接的联动调度方式确定工序组的开始时间, 避免了二次调整, 进一步降低了算法复杂度. 分析和实例表明, 所提出的综合算法比以往算法复杂度更低, 调度结果更优且更易于实现.     

From Profiles to Patterns: A New View of Task-Technology Fit

Continuing advances in the capabilities of communication and information technologies provide a wide array of interesting ways for people to collaborate across space, time, cultures, and organizational boundaries. While the use of collaboration technologies spreads, researchers seek answers to understanding how best to match different technology capabilities with the tasks that teams need to accomplish. Different theories of task-technology fit have been promoted and these theories help to identify key issues of interest to both researchers and practitioners who seek the answer to the best technology support for collaboration. We examine existing theories of fit for collaboration technology and propose a new view, using the theoretical frame of patterns. We argue that this fresh perspective is particularly relevant in the virtual contexts that are so important in the dynamic life of organizations today.     

改进的Prony算法提取舒曼谐振参数

为在更短的时间内提取舒曼谐振参数,引入对时域采样数据进行直接处理的Prony算法．针对该算法受噪声影响大的缺点,对算法的核心过程——超定方程的求解方法进行了改进,采用Martin等人提出的最小残数法,并与频域处理结果进行对比分析,验证该算法的有效性．     

基于人工蜂群算法的水位流量关系最优定线研究

在保凸保单调的分段幂函数的基础上,进一步引入自动分段机制,解决分段幂函数在水位流量关系拟合中分段点难以界定的问题.使用自动分段机制后的模型待求参数更多,求解更复杂,因此使用鲁棒性强、收敛速度快且全局寻优性能优异的人工蜂群算法进行求解.研究结果表明,引入人工蜂群算法可以更好的拟合关系曲线,水位流量关系曲线率定求解更加有效.     

基于LabVIEW的广义线性拟合在成本预测中的应用

成本预测在科研管理、生产管理等诸多方面有着广泛应用.使用图形化编程软件LabVIEW中“广义线性拟合Ⅵ”建立了成本预测的数学模型,实现了某产品的成本预测.结果分析表明,该方法是一种有效的数据处理方法,LabVIEW中不同方法的拟合函数使成本预测的实现与分析变得简单可靠.     

塑料联接件的设计制造和使用

介绍常用塑料铰链联接，搭扣联接，卡夹联接，压力装配联接的联接件材料选择，成型方法，联接原理，形状设计等。     

应用等效电路模型的频率选择表面有效分析

给出了一种基于等效电路模型的频率选择表面(FSS)快速分析方法。对任意形状单元的FSS结构,采用并联组合形式的LC等效电路,并通过全波模式展开分析,采用线性最小平方拟合和线性代数方法求得到其等效电路参数。对三极形单元夹嵌FSS结构实例的分析表明,文中方法与全波分析结果的一致性非常好,并便于FSS结构的最优化设计,可扩展到多层FSS结构的分析。