硫化罐齿啮式快开结构优化设计

为了降低硫化罐齿啮噬式快开结构的应力,通常应对的方法是设计时增加法兰的厚度,因此结构较笨重,产品竞 争力不强。为此文中提出采用ANSYS对DN800硫化罐整体相连卡箍齿啮式快开结构进行有限元分析,得到各部位的应 力分布;在满足强度和抗疲劳性能的前提下,分别采用安全裕度法、JB 4732应力评定法对状态变量进行提取,以体积最 小为优化目标,对结构进行优化设计,优化后体积分别减少了12. 8%和14. 1%。比较发现采用安全裕度法对状态变量 进行提取,计算效率高,便于工程推广。     

Risk patterns in drug safety study using relative times by accelerated failure time models when proportional hazards assumption is questionable: an illustrative case study of cancer risk of patients on glucose‐lowering therapies

Observational drug safety studies may be susceptible to confounding or protopathic bias. This bias may cause a spurious relationship between drug exposure and adverse side effect when none exists and may lead to unwarranted safety alerts. The spurious relationship may manifest itself through substantially different risk levels between exposure groups at the start of follow‐up when exposure is deemed too short to have any plausible biological effect of the drug. The restrictive proportional hazards assumption with its arbitrary choice of baseline hazard function renders the commonly used Cox proportional hazards model of limited use for revealing such potential bias. We demonstrate a fully parametric approach using accelerated failure time models with an illustrative safety study of glucose‐lowering therapies and show that its results are comparable against other methods that allow time‐varying exposure effects. Our approach includes a wide variety of models that are based on the flexible generalized gamma distribution and allows direct comparisons of estimated hazard functions following different exposure‐specific distributions of survival times. This approach lends itself to two alternative metrics, namely relative times and difference in times to event, allowing physicians more ways to communicate patient's prognosis without invoking the concept of risks, which some may find hard to grasp. In our illustrative case study, substantial differences in cancer risks at drug initiation followed by a gradual reduction towards null were found. This evidence is compatible with the presence of protopathic bias, in which undiagnosed symptoms of cancer lead to switches in diabetes medication. Copyright © 2015 John Wiley & Sons, Ltd.     

农产品质量安全源头监管的国际经验及其启示

农产品质量安全源头监管是食品安全监管和风险防控的关键环节,也是保证食品安全的重要措施。在总结分析国外农产品质量安全源头监管主要经验的基础上,从改革和完善农产品质量安全监管体制、建立完善协调的法律法规体系、建立和完善农产品残留监控体系、推进农产品认证的发展和监管、实行严格的监管制度和保障措施以及加强农产品源头风险分析和防控等方面对我国加强农产品质量安全源头监管提出对策建议。     

教育安全:界说、特征与意义

教育安全是指安全主体(个人、一类群体或国家)的教育(主)权、教育制度、教育传统以及自身教育发展等,能够经受来自外部或内部环境的各种威胁、干涉、侵蚀和挑战,并能够有效维护主体安全,保障安全主体教育功能得以充分实现的一种可持续发展的运行状态。教育安全呈现出假设性与现实性并存、内潜性与外显性同在、动态性与发展性相织、长期性与突发性相联四大特点。由于教育安全能使主体的教育权利得到保护并顺利实现、教育功能得以充分发挥并得到认同,并能有效抵御来自外部或内部威胁和挑战,因而教育安全日益受到世界各国的重视。     

探究思想政治教育在提升工科类研究生创新能力中的有效性

通过对工科类研究生创新能力素养的调研分析,指出在工科类研究生创新能力培养过程中,主要存在导师要素、培养条件、个人素质等方面的问题。文章分别从思想政治教育目标的有效性、思想政治教育内容的有效性、思想政治教育方式方法的有效性等方面,对如何发挥思想政治教育的有效性提升工科类研究生的创新能力,进行了探讨。     

管道工程实训基地的建设与实践

基于提高教学质量,保证相关专业的生产实习效果,充分发挥实验室现有资源,以管材及管配件的认识、管道连接、散热器组对、通风管道连接、空调机组、水泵的解体和安装为内容,建设校内管道工程实训基地。经过多年的建设与实践,取得良好成效,对促进教学改革、培养学生动手能力、提高综合素质具有重要的作用和意义。     

城市综合减灾规划设计的理论与实践——兼论2008北京安全奥运规划设计问题

2006年7月6日新华社转发《国务院关于全面加强应急管理工作的意见》〔以下简称《意见》),全文从六大方面,共计24条较为系统地论述了国家、地方全面加强应急管理工作的思路。《意见》在强调应急能力纳人政绩考核,学校社区应成为应急管理重点,要建成覆盖各地区、各行业各单位     

Sizing Inventory When Lead Time and Demand are Correlated

Determining appropriate inventory levels has been a subject of interest for both researchers and practitioners. Standard practice is to treat lead time demand as a random sum of random numbers and rely on established probability theory to calculate both reorder point and safety stock levels. A key assumption in these calculations, however, is that lead time and demand are not correlated. In this paper, we first explore situations where this assumption is untrue and then develop equations to determine the reorder point and the safety stock when lead time and demand are correlated. More specifically, we (1) derive formulas for the average and variance of the demand in a lead time, which can then be used to calculate the reorder point and the safety stock, (2) apply these formulas to two distributions for which there is a closed‐form solution: normal and Poisson, and (3) examine the effect of correlation on safety stock requirements under the normal distribution.     

电子信息专业本科学生工程实践能力培养途径探析

给出了培养电子信息专业学生工程实践能力的几种途径,并对其内容、意义、方法和手段进行了探讨和实践。合理设置、有效利用开放实验室、专业综合实验、生产实习、教学实习、认识实习、毕业设计及电子设计竞赛等实践环节,以适应当代电子信息类专业发展的需要,实现"知识+能力+创新"型实用专业人才的目标。     

创新：经管专业“工科特色”人才培养模式的最佳选择

培养模式直接决定着人才素质的高低。工科院校经管专业的课程设置,需要结合学校工科品牌专业的实际,以社会需求为导向,整合全校资源进行课程建设。对强势的工科专业与经管专业形成良性互动的机制,逐渐形成工科院校经管专业的工科特色进行了有益的探讨。