高职《平面四杆机构急回特性》教法浅析

急回特性是平面四杆机构的基本性质之一。对急回特性的分析是高职《机械基础》教学中的一个重点和难点,如何将四杆机构动态过程中发生的急回现象在授课中清楚、形象地展现出来,让学生易于接受、听懂、学会,不仅需要从教学环节上精心设计,还需利用现代化教学手段等多方面着手,才能达到良好的教学效果。     

Simulating Ruin Probabilities for a Class of Semimartingales by Importance Sampling Methods

We consider the problem of finding the probability of ruin when the risk process is assumed to be a special semimartingale with absolutely continuous characteristics. We show how the generalized Girsanov theorem can be used in connection with Monte Carlo simulation to obtain estimates of the ruin probabilities. It is shown by both analytical and numerical examples that these methods can be significantly better than ordinary simulations provided the new measure is chosen with some care.     

浅析施工降水的回收利用

水是生命之源,没有水就没有地球上的生物,也就没有人类的今天。我国是水资源短缺的国家,城市缺水问题尤其突出。本文主要阐述了水资源的短缺的现状,对施工降水的前景与现状进行分析,对如何进行有效地回收利用施工降水的方式等进行探讨。     

某大厦基坑边坡支护与降水设计

深基坑施工是建设地下停车场的首要工程,如何才能保证基坑的稳定及基坑周边环境的安全,已成为基坑工程设计、施工中的难点和重点。本文作者某大厦基坑开挖工程实例,主要就大口径井点降水设计及钻孔灌注桩边坡支护设计的过程进行了阐述。     

Commodity market risk from 1995 to 2013: an extreme value theory approach

In this article we examine whether extreme risk has increased in the agricultural commodity market during the period 1995–2013. We add to the literature on food price volatility by analysing the tail segment of futures price return distributions. Food price variability is a concern for governments and regulators worldwide, as most nations trade in food. High food price variability can contribute to poverty and malnourishment, in particular for people in less economically developed economies. We find no indications of systematically increasing tail-risk for the commodities in our sample. Analysis of estimated shape-parameters of the Generalized Extreme Value distribution further supports the conclusion that there is no general systematic change in the extreme risk associated with these commodity investments.     

基于极限学习机网络的中小企业成长性研究

根据适合中国中小企业成长性评价的指标体系,提出了一种基于极限学习机神经网络的评价模型,并以2011年前上市的30家中小企业为例,验证了这种评价方法对中小企业成长性的基本适用性。结果表明,该评价方法应用在中小企业成长性评价系统中具有很高的评价准确率。最后根据对中小企业的实证研究结果对其成长性评价作了简单总结,并对现阶段中国中小企业的成长提出了建议措施。〖HJ4mm〗     

Occupational transition and country-of-origin effects in the early stage occupational assimilation of immigrants: some evidence from Australia

We examine the occupational attainment of recent immigrants at 2 years post migration in order to study their early stage assimilation into the labour market in Australia. Human capital endowments and country-of-origin effects are examined for six occupational groups. We also study transitions across occupations from source to host country. The empirical approach utilizes the Ordered Generalized Extreme Value (OGEV) model which embodies differing utility functions across occupational outcomes, as well as accounting for any ordering in these outcomes. The results suggest that the transferability of knowledge and skills is affected by cultural and social backgrounds, and that non-Western immigrants are disproportionately channelled into inferior jobs post migration. The investigation of the country-of-origin effect on the skilled migrants’ occupational transition process is especially apt in the context of skill shortages in many host countries.     

响应面法优化豌豆分离蛋白提取工艺

试验采用碱溶酸沉的方法提取豌豆分离蛋白,探讨各个因素对提取率的影响。研究了料液比、浸泡时间、浸泡温度、pH对豌豆分离蛋白提取率的影响。利用响应面分析法优化工艺参数,最后确定豌豆分离蛋白的最佳提取条件为：料液比1：23,浸泡时间53min,浸泡温度47℃,pH8．8,其中蛋白质含量高达90．24％。     

微波遥感反演降水量算法研究进展

降水量是衡量一个地区在某段时间内降水多少的数据,对了解全球水汽循环具有重要意义。在深入分析基于SSM/I资料的相关算法、基于TRMM卫星微波遥感资料的反演算法和物理廓线法等几种常用降水量微波遥感反演算法的基础上,指出了利用微波遥感反演降水量存在的问题和不确定性因素,为更好地选择反演所用的数据源、优化反演流程和提高反演精度提供了借鉴意义。