Effective elements of care-physical activity initiatives for adults with a low socioeconomic status: A concept mapping study with health promotion experts

In care-physical activity (care-PA) initiatives, primary care and sports are combined to stimulate PA among adults at risk of lifestyle related diseases. Preliminary results from Dutch care-PA initiatives for adults with a low socioeconomic status (SES) indicate a decrease in participants’ body weight and an improved quality of life, however, the elements that make these initiatives successful are yet to be identified. In total, 19 Dutch health promotion experts participated in our concept mapping (CM) of the effective elements of care-PA initiatives for adults with a low SES. The experts identified 111 effective elements of these initiatives, which were grouped into 11 clusters, focusing on: 1) approaching participants within the care-PA initiative, 2) barriers experienced throughout the initiative, 3) long-term implementation, 4) customizing the care-PA initiative to the target population, 5) social support, 6) structure and guidance, 7) the professionals within the care-PA initiative, 8) the accessibility of the care-PA initiative, 9) targeted behaviour and progression, 10) recruitment and administration, and 11) intersectoral collaboration. CM was useful for creating a valuable overview of these effective elements. Our results could be used to improve the development and implementation of future care-PA initiatives for adults with a low SES.     

网络视频实时在线评论用户认可度的影响因素

目前，网络视频实时在线评论激增带来的信息爆炸，使实时在线评论信息管理成为重要议题。以往对实时在线评论的研究多集中于个人行为结果方面，而缺乏对实时在线评论信息管理问题的关注；同时，现有视频网站对实时在线评论信息的管理也存在诸多局限。以爱奇艺视频网站热度榜中的电影为样本，基于信息质量维度框架并采用Tobit模型对实时在线评论用户认可度的影响因素进行研究，结果发现：实时在线评论的新颖性、相似性、情感倾向性和信息丰富性，均对实时在线评论的用户认可度存在显著影响，其中新颖性和相似性影响作用最大。视频网站可以据此进一步强化实时在线评论管理，改善用户的体验，保持用户的粘性。     

Modeling Finite‐Time Failure Probabilities in Risk Analysis Applications

In this article, we introduce a framework for analyzing the risk of systems failure based on estimating the failure probability. The latter is defined as the probability that a certain risk process, characterizing the operations of a system, reaches a possibly time‐dependent critical risk level within a finite‐time interval. Under general assumptions, we define two dually connected models for the risk process and derive explicit expressions for the failure probability and also the joint probability of the time of the occurrence of failure and the excess of the risk process over the risk level. We illustrate how these probabilistic models and results can be successfully applied in several important areas of risk analysis, among which are systems reliability, inventory management, flood control via dam management, infectious disease spread, and financial insolvency. Numerical illustrations are also presented.     

基于FLOTRAN的燕尾形导轨气浮平台结构设计

闭式燕尾形导轨是常见的静压气浮导轨结构形式之一,其燕尾角度将直接影响导轨的承载能力,为保证设计的燕尾形导轨能满足工作要求,本文通过建立燕尾夹角在55°~70°范围变化的气膜有限元模型,以承载力和刚度作为主要性能指标,对导轨承载能力进行分析.通过分析发现:导轨垂直方向总承载力随着燕尾夹角θ的增大而增大.研究结果表明燕尾夹角θ=66°时,单边导轨垂直方向的承载力为87.26N,刚度为33.69N/μm,能较好地满足承载和工作要求.     

位移边界对2D-FGM板热应力影响研究

考虑不同的位移边界条件,建立了常物性2D-FGM板研究模型,并采用有限元法,得到其冷却瞬态热应力场分布图形。位移边界条件对常物性2D-FGM平面区域冷却瞬态热应力分布影响颇大,在简支和一端固定情况下,2D-FGM板自由边界上的热应力σ_x=0;两端固定情况下,其左右两边界均形成上中下三个应力聚集,应力分布形状和数值都发生了巨大的变化;将四周均设置呈固定约束后,热应力数值增长幅度较两端固定情况时更为明显。此结果为该材料的设计、制备提供了准确的理论计算依据。     

基于Shapley值法的移动增值服务价值链利润分配模型

研究对象为任意节点连接和任意支撑的平面框架。一般梁单元由等截面直杆及其杆端的轴向弹簧、切向弹簧和转动弹簧组成，推导得到此类单元的刚度矩阵、单元在8种基本荷载作用下的等效节点荷载。采用Matlab语言编写了适用于一般节点非线性连接框架的静力分析程序，非线性形式为指数函数或多项式函数，可以得到结构不同连接刚度下的节点位移、杆端位移和杆端力。算例显示出节点柔度对结构受力和变形的影响。     

Mixture inverse Gaussian for unobserved heterogeneity in the autoregressive conditional duration model

In this paper, we assume that the duration of a process has two different intrinsic components or phases which are independent. The first is the time it takes for a trade to be initiated in the market (for example, the time during which agents obtain knowledge about the market in which they are operating and accumulate information, which is coherent with Brownian motion) and the second is the subsequent time required for the trade to develop into a complete duration. Of course, if the first time is zero then the trade is initiated immediately and no initial knowledge is required. If we assume a specific compound Bernoulli distribution for the first time and an inverse Gaussian distribution for the second, the resulting convolution model has a mixture of an inverse Gaussian distribution with its reciprocal, which allows us to specify and test the unobserved heterogeneity in the autoregressive conditional duration (ACD) model.

Our proposals make it possible not only to capture various density shapes of the durations but also easily to accommodate the behaviour of the tail of the distribution and the non monotonic hazard function. The proposed model is easy to fit and characterizes the behaviour of the conditional durations reasonably well in terms of statistical criteria based on point and density forecasts.     

无时间性的真无限：黑格尔哲学初期的一个关键问题

1803年前，黑格尔对时间问题缺乏关注。相形之下，在1807年《精神现象学》中，他已将时间看作哲学的重要主题。为什么黑格尔从1795到1802年曾对时间问题无动于衷。在1795年左右，黑格尔主要关注爱的无限性问题。在其法兰克福时期和耶拿初期，他虽然看到了时间性的客观世界的地位，但却并未对此加以强调，而只是强调了主体性的爱与客体性的世界的统一的绝对自身。1802年，通过研究雅各比和康德关于时间问题的争论，黑格尔刻意歪曲了雅各比哲学中的时间问题的重要性，以自己的方式，将时间性的有限存在者问题与物自身问题连接进行考察，从而以一种哲学性的真无限问题策略性地取代了时间问题。这一策略运用与黑格尔原初性的哲学体系理解直接相关，由此，黑格尔将雅各比哲学与康德哲学一并归类为反思性哲学，并对之加以“超越”。     

基于ANSYS的压力容器表面凹坑缺陷安全评定分析

采用通用有限元程序ANSYS建立了移动式压力容器筒体外壁表面凹坑（轴向和周向）的有限元模型。结合筒体表面凹坑的应力理论计算，研究探讨了在恒定内压下，筒体表面凹坑缺陷处的应力分布与凹坑几何尺寸之间的关系。以第三强度理论作为仿真终止判据，获取凹坑各几何参量的阈值，利用MATLAB对阈值进行最小二乘拟合，绘制出凹坑缺陷的安全评估参考曲线。拟合结果表明：轴向和周向凹坑对筒体局部结构强度的影响不同，对应的安全评估参考曲线存在区别。     

井眼倾斜角和倾斜方位对裸眼完井地层出砂的影响

结合等效塑性应变准则定量地研究了井眼倾斜角和倾斜方位对裸眼完井砂岩油藏出砂的影响。计算结果表明,在一定的应力和地层条件下,井斜角在0~45°时,随着井斜角的增加,井壁内的塑性应变最大值和塑性区范围都不断增加,出砂的趋势增大;当井斜角在45°~90°时,随着井斜角的增加,井眼内最大塑性应变逐渐减小,出砂趋势减小。井斜角相同,但井眼倾斜方位不同的井,井壁内产生塑性变形的区域不同,塑性变形的程度也不同,从防砂的角度,井眼,尤其水平井眼应该沿原地最小水平主应力方向,或尽可能靠近最小主应力方向。