双螺杆泵Ω形对称型螺杆流场数值分析

由于螺杆泵几何结构及流体流动状态较为复杂,其压力分布和速度等特性很难用数学解析法来分析计算。本文利用参数化设计模块建立双螺杆泵Q形对称型螺杆三维模型,构建双螺杆流道的流场分析模型,运用有限元分析方法得出了双螺杆泵流道内压力场和速度场分布规律。结果表明：流体在流道中的流速分布具有规律性,整个流道的流场速度高低交替变化,在螺杆与衬套间隙处的流动为层流,螺旋面接触区内的流动为复杂的湍流,离螺杆啮合区近的螺旋槽内易发生涡流。本研究结果对于了解双螺杆泵螺杆工况下的性能情况具有重要的参考价值。     

新型Cr12Mo1V1剪切刀具的破坏分析与结构优化

针对目前新型Cr12Mo1V1剪切刀具在使用中频繁发生破坏行为,采用三维有限元方法系统研究了该刀具在切割工况下的力学行为。先得到了该刀具的详细应力场,确定其危险部位,并基于经典强度理论对其破坏进行了分析与校核;详细研究了刀具在出现不同几何尺寸的三维角裂纹时,其裂纹前缘应力强度因子的分布结果。基于这些结果对该刀具的几何结构与尺寸进行了优化,降低了应力水平,提高了抗断裂强度。     

基于ANSYS的热成形模具结构优化

基于冲压成型工艺试验分析系统,针对模具内材料受热膨胀将对模具导向装置及结构造成干涉的问题,利用有限元分析软件ANSYS对模内温度场进行热力耦合分析,得出各部分材料的热膨胀程度。为基于正向压边模架的模内加热装置提供可靠的实验参数和热力学设计依据,提高了模具结构设计的合理性,达到优化设计的目的。     

基于FLUENT的管壳换热器壳程流场数值模拟与分析

通过简化管壳式换热器模型,采用非结构网格划分,选用κε湍流模型,应用CFD软件FLUENT对壳程流体流动和传热过程进行了数值模拟,得到了不同折流板间距情况下壳程流体温度场、压力场以及速度场的分布情况。分析了折流板间距对壳程流体流场分布、换热器传热速率以及压力损失的影响,并得出了进口流速与传热量和压力损失之间的关系。模拟结果与理论研究结果相符合,对管壳式换热器的设计和改进有一定的参考价值。     

基于ANSYS CFX的安全阀开启过程的数值模拟

以A42Y型弹簧式安全阀为研究对象,利用ANSYS CFX软件对安全阀开启过程进行数值模拟,得到了安全阀从开始开启到稳定排放阶段介质对阀瓣作用力随时间的变化曲线,以及特定时刻的压力场分布。并且根据安全阀稳定排放时的介质作用力计算得到流道等效半径,对安全阀开启过程动态特性研究以及安全阀在线校验中流道有效面积计算提供了一定的指导和依据。     

失地农民的心理场及其重构——基于“仙居雅苑”安置社区的个案研究

失地农民的心理变化不仅仅是结构性的,也是过程式的。心理的结构性变化侧重反映失地农民心理内容,心理的动态过程反映的是失地农民心理场的“移位”。     

Moment‐Independent Sensitivity Analysis Using Copula

In risk assessment, the moment‐independent sensitivity analysis (SA) technique for reducing the model uncertainty has attracted a great deal of attention from analysts and practitioners. It aims at measuring the relative importance of an individual input, or a set of inputs, in determining the uncertainty of model output by looking at the entire distribution range of model output. In this article, along the lines of Plischke et al., we point out that the original moment‐independent SA index (also called delta index) can also be interpreted as the dependence measure between model output and input variables, and introduce another moment‐independent SA index (called extended delta index) based on copula. Then, nonparametric methods for estimating the delta and extended delta indices are proposed. Both methods need only a set of samples to compute all the indices; thus, they conquer the problem of the “curse of dimensionality.” At last, an analytical test example, a risk assessment model, and the levelE model are employed for comparing the delta and the extended delta indices and testing the two calculation methods. Results show that the delta and the extended delta indices produce the same importance ranking in these three test examples. It is also shown that these two proposed calculation methods dramatically reduce the computational burden.     

Effect of cigarette smoking on sexual functions,psychological factors,and disease activity in male patients with ankylosing spondylitis

Objective: This study aims to investigate the effect of smoking on sexual functions in AS patients.

Patients and methods: A total of 67 male AS patients with a median age of 34 years (range: 18–57) reporting sexual activity at least for the past 4 weeks period were included. Patients were divided into smokers (Group 1, n?=?47) and non-smokers (Group 2, n?=?20). Fagerström test for nicotine dependence, smoking history, exhaled carbon monoxide test were recorded for smoking AS patients. Visual analogue scale (VAS), Bath Ankylosing Spondylitis Disease Activity Index (BASDAI), Bath Ankylosing Spondylitis Metrology Index (BASMI), Bath Ankylosing Spondylitis Functional Index (BASFI), Ankylosing Spondylitis Quality of Life (ASQoL), International Index of Erectile Function (IIEF), Beck Depression Inventory (BDI) were filled for both groups.

Results: There was no significant difference between smokers and non-smokers in all evaluation parameters. BASMI scores were significantly lower in the mild dependency subgroup as compared to those with moderate or severe dependency (p?=?.005 and p?=?.007, respectively). Total IIEF score and IIEF categories correlated significantly with BASDAI, BASFI, BASMI, ASQoL, pain, fatigue, and cumulative smoking. BDI showed an inverse correlation with the IIEF score and IIEF category (p?r?=?–0.520, p?r?=?–0.508, respectively).

Conclusions: Sexual function in AS patients is associated with the pain, fatigue, disease activity, functional status, quality of life, depression as well as the cumulative exposure to smoking, and that sexual functions tend to decline with increasing degree of cigarette dependency.