集簇式焊钉连接件抗剪承载力试验及计算方法

为了深入研究集簇式焊钉连接件的抗剪性能,结合装配式钢混组合桥梁焊钉连接件布置特征,以焊钉层间距和焊钉排数为变化参数,设计并完成了5组共10个焊钉连接件的静力推出试验,并建立了25组集簇式焊钉连接件精细化有限元模型,提出了同时考虑焊钉层间距和焊钉排数引起的群钉效应的单钉抗剪承载力折减系数计算公式。试验和分析结果表明：集簇式焊钉连接件受剪作用下由于各排焊钉之间剪力传递的不均匀性出现分批剪断现象,焊钉层间距较小时,各层焊钉之间混凝土破坏区域发生重叠,削弱了焊钉的抗剪承载力;与单钉连接件的荷载-滑移曲线特征不同,集簇式焊钉连接件持荷段较长,呈现出较好的延性,其破坏阶段呈阶梯状分布规律,验证了各排焊钉之间的承剪不均匀现象;单钉平均抗剪承载力随焊钉层间距增大而增大,随焊钉排数的增加而减小,当焊钉层间距超过8d时,可忽略其对抗剪承载力的影响;受预制桥面板预留剪力槽孔尺寸限制,装配式钢混组合桥梁常用的集簇式焊钉连接件层间距取值为4d～8d,排数取值为3r～7r;基于推出试验和有限元参数分析结果提出了同时计入焊钉层间距和焊钉排数的集簇式焊钉连接件抗剪折减系数实用计算公式,可为装配式钢混组合桥梁中集簇式焊...     

Contrasts between utility maximisation and regret minimisation in the presence of opt out alternatives

An increasing number of studies of choice behaviour are looking at Random Regret Minimisation (RRM) as an alternative to the well established Random Utility Maximisation (RUM) framework. Empirical evidence tends to show small differences in performance between the two approaches, with the implied preference between the models being dataset specific. In the present paper, we discuss how in the context of choice tasks involving an opt out alternative, the differences are potentially more clear cut. Specifically, we hypothesise that when opt out alternatives are framed as a rejection of all the available alternatives, this is likely to have a detrimental impact on the performance of RRM, while the performance of RUM suffers more than RRM when the opt out is framed as a respondent being indifferent between the alternatives on offer. We provide empirical support for these hypotheses through two case studies, using the two different types of opt out alternatives. Our findings suggest that analysts need to carefully evaluate their choice of model structure in the presence of opt out alternatives, while any a priori preference for a given model structure should be taken into account in survey framing.     

直接还原铁（C）海上运输安全监管的探讨

文中针对事故原因进行分析，提出加强载运直接还原铁（C）船舶的申报管理，严格审批程序，增加抵港前申报制度，建立评估机制，加大处罚力度，针对船员进行专业培训等安全监管措施.     

民营科技企业融资困难的原因和对策探讨

从企业内部和外部两个方面分析了民营科技企业融资困难的原因，在此基础上提出解决融资问题的对策建议：（1）在思想认识上，应坚持“三要三不要”原则和制定“有所为，有所不为”的重点资助计划；（2）在融资体系的建设上，应从企业、政府和国际三个层次来建设“多层次、多渠道、全方位”的融资体系。     

树枝形专用线取送车问题的研究

本文基于树枝形专用线取送车作业的特点，就非直达车流连送带取（含单送、单取）这种常见情况进行分析，提出了三个优化目标，并给出了简便易行的优化方法。     

铁路特长单线隧道钻爆施工机械配置探讨

本文介绍了在建渝怀铁路最长单线隧道——圆梁山隧道的施工机械配置情况，阐明了采用常规施工方法(全断面法或下导坑法)及配置国产设备亦能实现铁路特长单线隧道掘进速度的稳产和高产，论述了施工机械设备的良好配置是确保持长隧道快速掘进的关键所在，同时对今后我国特长单线隧道的机械配置提出几点建议。     

双层组合外套液压联轴器分析

介绍船用轴系液压联轴器的组成，并对液压联轴器双层外套进行了分析，确定了双层外套内、外层之间界面的最佳半径。     

Improved List Sphere Decoder for Multiple Antenna Systems

An improved list sphere decoder （ILSD） is proposed based on the conventional list sphere decoder （LSD） and the reduced- complexity maximum likelihood sphere-decoding algorithm. Unlike the conventional LSD with fixed initial radius, the ILSD adopts an adaptive radius to accelerate the list cdnstruction. Characterized by low-complexity and radius-insensitivity, the proposed algorithm makes iterative joint detection and decoding more realizable in multiple-antenna systems. Simulation results show that computational savings of ILSD over LSD are more apparent with more transmit antennas or larger constellations, and with no performance degradation. Because the complexity of the ILSD algorithm almost keeps invariant with the increasing of initial radius, the BER performance can be improved by selecting a sufficiently large radius.     

弘扬和承继历史留下的宝贵精神财富——《中国近现代史纲要》教学札记

历史留下的宝贵精神财富,是构成现实生活不可缺少的重要组成部分,是立国强国不可缺少的精神条件。中国近现代史上留下的宝贵精神财富十分丰富,包括以爱国主义为核心的民族精神,敢于创新、独立自主的精神,艰苦创业、为人民服务的精神等。弘扬和承继这些宝贵精神财富并将其贯注到“纲要”课教学之中去,是充分发挥历史教育的价值功效、更好实现“纲要”课程教学目的、增强该课程教学效果的一个不可或缺的重要方面,也是传承中华民族精神、落实我党在新的施政理念下提出的新任务、促进自我修身发展的必然要求。对此担负“纲要”课程教学的教师理应责无旁贷地肩负起这一神圣使命和职责。