高旋仪步进电机可变微分技术

本文着重讨论新研制的高温高压泥装旋转拈度、失水仪中步进电机微分技术，用以解决低转速下仪器的测量精度问题。     

On parallel policies for ranking and selection problems

In this paper we develop and test experimental methodologies for selection of the best alternative among a discrete number of available treatments. We consider a scenario where a researcher sequentially decides which treatments are assigned to experimental units. This problem is particularly challenging if a single measurement of the response to a treatment is time-consuming and there is a limited time for experimentation. This time can be decreased if it is possible to perform measurements in parallel. In this work we propose and discuss asynchronous extensions of two well-known Ranking & Selection policies, namely, Optimal Computing Budget Allocation (OCBA) and Knowledge Gradient (KG) policy. Our extensions (Asynchronous Optimal Computing Budget Allocation (AOCBA) and Asynchronous Knowledge Gradient (AKG), respectively) allow for parallel asynchronous allocation of measurements. Additionally, since the standard KG method is sequential (it can only allocate one experiment at a time) we propose a parallel synchronous extension of KG policy – Synchronous Knowledge Gradient (SKG). Computer simulations of our algorithms indicate that our parallel KG-based policies (AKG, SKG) outperform the standard OCBA method as well as AOCBA, if the number of evaluated alternatives is small or the computing/experimental budget is limited. For experimentations with large budgets and big sets of alternatives, both the OCBA and AOCBA policies are more efficient.     

Applying the Housing First approach to single-site permanent supportive housing

This study explored how the U.S. Departments of Housing and Urban Development-Veterans Affairs Supportive Housing (HUD-VASH) program applies Housing First principles in the context of ten single-site programs. Focus group discussions with 64 HUD-VASH staff and community partners explored how the programs were influenced by Housing First principles and specific strategies to implement these principles in a single-site setting. Focus group respondents described resourceful ways that the principles of Housing First were implemented in their programs specifically related to (1) housing choice and structure, (2) separation of housing and services, (3) service philosophy, and (4) service array. Several of the Housing First domains cite the importance of integrated housing and the provision of services off-site; it was of particular interest to learn how single-site programs address these issues logistically. Lessons learned from this study include the importance of leveraging the independent yet overlapping tasks of case management and property management to ensure functional – if not geographic – separation of housing and services; maintaining staff on-site to address Veterans’ needs; working with community service organizations to complement the array of service available to residents; and housing single-site programs in mixed-use buildings.     

The role of eviction in veterans’ homelessness recidivism*

Eviction is one of the leading causes of homelessness in the U.S.A. Though permanent supportive housing (PSH) helps participants maintain housing, some still leave due to eviction. This study aimed to determine whether eviction is an important predictor of recidivism and time to return to homelessness for participants exiting PSH. The characteristics and post-exit service use of 2802 Veteran PSH participants were analyzed based on exit reason. A Cox proportional hazards survival analysis modeled risk factors for returning to homelessness within 360 days of exit. Compared with other exiters, evicted Veterans remained in the program for less time, were less likely to be receiving service-connected compensation, and used more services – particularly mental health and substance use services – following their exit, and those who returned to homelessness did so more quickly. Identifying participants who might benefit from more intensive services, project-based housing, or income supports may prevent evictions and subsequent returns to homelessness.     

“90后”大学生思政课教学新思路探析——以宁夏师范学院为例

＂90后＂大学生群体具有坚定的政治信仰、强烈的爱国热情、明确的价值取向;生活态度总体上积极健康,人生目标明确。但是由于各方面原因,这一群体对未来充满了不确定感,紧张、压抑、焦虑的情绪比较严重,如果不能妥善引导和疏通,情况堪忧。高校思政理论课在解决这些问题上发挥着重要作用。因此,思政课应从构建和谐师生关系和创新教学方法等方面,提高其教学实效性。     

湖北农村居民持久收入与消费的协整分析

一般认为,持久收入是决定居民消费需求的基本因素。采用湖北省1978-2009年的农村居民持久收入与消费支出的年度统计数据,对湖北省农村居民的实际持久收入与消费进行协整分析。结果发现,湖北省农村居民的长期和短期消费弹性分别是0．857和0．728,二者之间存在着长期均衡和短期波动调整关系,持久收入是影响消费需求的决定性因素。在此基础上,提出相应政策建议,即大力提高农村居民的持久收入,从根本上激活农村消费市场和提高农村居民的消费水平。     

论机动车所有权转移的生效要件

机动车是一种特殊的财产,传统的民法理论将其视为不动产,而《物权法》又将其归属为动产。机动车的所有权的认定,无论是在司法实践中,还是在法学理论上,都是一个重要问题。法学界对于机动车所有权转移的生效要件,基本可以分为登记说、交付说、合同生效说三种观点。登记是不动产所有权转移的生效要件,不应运用在作为动产的机动车的所有权转移上。合同生效与所有权转移分别是债权问题与物权问题,不应混淆。因此,只有交付才能作为机动车所有权转移的生效要件。     

基于FPGA的可重构数控系统

利用FPGA丰富的逻辑资源及其内部可编程的特点,文章提出了可重构数控系统硬件设计方法及以FPGA为控制核心的数控系统设计方案,重点分析了对电机的速度控制及与PC机的串行通信等,开发了以FPGA为控制核心的经济型数控系统。其响应速度快,可重构性强,大大减少了系统的外围接口器件,同时有效降低了系统成本。     

交流电机变绕组匝数拓宽调速范围的新方法

在典型交流电机调速应用领域需要拓宽电机的调速范围。传统的拓宽电机调速范围的方法主要包括弱磁调速、 变极调速以及改变绕组结构等。针对电动汽车驱动电机应用背景,提出了一种拓宽交流电机调速范围的新方法,即在维 持电机本体结构与变频器功率等级基本不变的情况下,利用由少量全控和不控电力电子器件构成的绕组调节功率变换 电路,实现电机定子绕组等效匝数的连续可调。仿真结果表明,定子绕组等效匝数是可以通过脉冲控制方法实现连续可 调的,应用该方法,可以拓宽电机的调速范围,使其适应不同应用场合对电机转矩曲线的要求。     

基于单片机的步进电机控制系统的设计

采用AT89S51单片机,设计了步进电机控制系统,该系统主要由按键电路、单片机最小系统、AT89S51单片机、步进电机状态显示电路、驱动电路以及步进电机等几部分组成,不仅可以实现电机的正反转,还可以实现17级调速,以及LED状态显示功能.系统设计可靠且易于实现,程序设计简单易懂.