带法兰盘的阶梯轴冷镦挤成形工艺研究

为了研究法兰盘阶梯轴零件成形过程,确定其合理的工艺方案,课题组运用Deform 3D软件对带法兰盘阶梯轴零件镦挤过程进行数值模拟。通过模拟结果对初定工艺方案进行分析,确定了3步成形工艺,并对该工艺进行改进。基于正交试验对改进工艺进行优化,综合模具载荷、折叠角大小和分布及应力分布等因素,确定了最佳的工艺方案。结果表明：采用3步成形工艺时,对法兰盘进行2步镦粗成形,即采用挤压法兰盘1次镦粗 法兰盘2次镦粗成形工艺,该工艺可有效降低模具载荷、折叠角的角度和面积及零件应力;且当压力机工作速度为5 mm/s,法兰盘拐角处模具圆角半径为5 mm,摩擦因数为0.05时,工件成形质量较优。通过实际生产获得了表面质量良好的法兰盘阶梯轴零件。     

广州驻防八旗生计问题探析

摘要：满清定都北京以后,八旗军民合一的体制被打破,清政府为维护政权的稳固,分派八旗军在全国多处驻防。广州八旗在 驻防初期,有钱粮制度作保障,且旗民人口较少,因此,旗民生活较为宽裕,但随着清政府财政的枯竭,广州八旗旗民人口的增 长,广州驻防八旗旗民面临着严峻的生计问题,虽然广州采取了四项主要措施来解决旗民的生计问题,但这些措施对于多数生 计维艰的八旗旗民来说,仍是杯水车薪,最终广州八旗旗民突破了八旗驻防制度的种种束缚,开始自谋生路     

Stochastic modelling of the hybrid survival curve

In this paper, building upon the idea of cross-sectional survival probabilities developed by Brouard (Espaces Popul Soc 2(14–15):157–168, 1986), we propose using stochastic models to study the evolution of a new type of survival curves called hybrid survival curve. We find that the three-factor survival model provides a better model fitting than the two-factor survival model. Furthermore, the three time-varying parameters are highly interpretable and their respective trends can be used as an indicator for the rectangularisation of survival curve. On top of that, we demonstrate how the time-varying parameters can be extrapolated into the future to obtain projected hybrid survival curves.     

同态滤波在扭矩载荷识别中的应用

通过理论分析和实验验证,证明了采用同态滤波的方法识别机器扭矩载荷的可行性。同时提出了根据时序模型的Ｇｒｅｅｎ函数来判定窗函数宽度的方法,减少了选取窗函数宽度的盲目性。作为应用实例,给出了采煤机扭矩的识别结果。     

Increasing Returns and Social Contagion in Cultural Industries

A formal definition of cultural industries is developed following four distinct features of cultural goods: (a) oversupply, (b) quality uncertainty, (c) network effects and (d) demand reversal. Drawing on economic and socio-psychological notions of ‘network’, increasing returns and social contagion effects are distinguished. Increasing returns may govern the adoption of standards when choices are binary, social contagion explains the diffusion of cultural goods when choices are multiple. Together, the four structural features delineating cultural industries account for curious competitive dynamics prevalent in cultural markets, such as the notorious 10 : 90 proportionality (under which 10% of cultural goods account for 90% of the market), causal ambiguity about the reasons for success, and the formation of fashions. Six managerial recommendations are advanced, focusing on a criticial circulation point triggering self-sustaining diffusion patterns. Finally ‘project-based enterprises’ and ‘network forms of governance’ are identified as the organizational forms most suited to the dynamics of the cultural markets.     

论唐代前期"河曲"地域各民族人口的数量与分布

唐代前期"河曲"地域人口的民族构成包括汉、稽胡、突厥、铁勒九姓、昭武九姓、党项羌、吐谷浑等七个民族,其数量与分布呈动态变化.贞观二十年前,"河曲"人口数量可达180,000余人,其中汉族、稽胡族人口约有50,000人,分布在"河曲"边缘地带,突厥族游牧于"河曲"东半部的夏、胜二州之间以及西北隅,昭武九姓居留在"河曲"西部的灵、盐、夏之间.此后,由于吐谷浑族、党项羌族、铁勒族的迁入,居民数量与空间分布发生新的变化.迄天宝元年,"河曲"地域的人口总数已达750,137人.安史之乱后,铁勒九姓、突厥、昭武九姓、吐谷浑诸族人口相继迁出"河曲",惟有汉、稽胡、党项羌诸族人口仍留居原地,尤其以党项羌人口增长显著,分布范围不断扩大,遍及"河曲"地域,成为当地人口的主体.     

疫情防控背景下毕业设计(论文)改进策略研究

毕业设计(论文)是培养本科人才的重要教学环节,2020年新冠肺炎疫情的暴发对毕业设计(论文)工作产生一定的影响.该文以广东石油化工学院化学工程与工艺专业为例,从学校、学院、专业三个维度介绍为应对疫情影响所采取的措施,分析存在的问题,并提出未来的持续改进策略,以提高学生从事工程设计和科学研究的能力.     

CDIO教育理念下的法律人才培养方式改革

文章提出了当前、法学教育所存在的问题,试图从培养职业道德、优化知识结构和训练实践能力三方面探讨如何引入CDIO教育理念,以改革传统的法学教育教学方法,尽快提高法律人才的质量.     

On Variational Bayes Estimation and Variational Information Criteria for Linear Regression Models

Variational Bayes (VB) estimation is a fast alternative to Markov Chain Monte Carlo for performing approximate Baesian inference. This procedure can be an efficient and effective means of analyzing large datasets. However, VB estimation is often criticised, typically on empirical grounds, for being unable to produce valid statistical inferences. In this article we refute this criticism for one of the simplest models where Bayesian inference is not analytically tractable, that is, the Bayesian linear model (for a particular choice of priors). We prove that under mild regularity conditions, VB based estimators enjoy some desirable frequentist properties such as consistency and can be used to obtain asymptotically valid standard errors. In addition to these results we introduce two VB information criteria: the variational Akaike information criterion and the variational Bayesian information criterion. We show that variational Akaike information criterion is asymptotically equivalent to the frequentist Akaike information criterion and that the variational Bayesian information criterion is first order equivalent to the Bayesian information criterion in linear regression. These results motivate the potential use of the variational information criteria for more complex models. We support our theoretical results with numerical examples.     

国际金融资产组合的选择--论短期国际资本流动的成因

资本的本质是追求利润。但是,由于不同国家不同的金融资产存在不同的风险,短期资本寻求的不是收益的最大化,而是收益和风险的最优组合;又由于不同的投资者对待风险的态度存在差异,收益和风险的最优组合取决于投资者承担风险的意愿。因此,短期资本流动是由金融资产的收益、金融资产的风险和投资者对风险的态度决定的。在这个领域,马柯维茨(HarryM.Markowitz)作出了杰出的贡献。但是,马柯维茨主要研究国内证券最优组合的选择。本文对短期国际资本流动进行重新定义以后,把马柯维茨以及后人的研究成果加以概括和发挥并用于解释短期国际资本流动的成因。