超重力模拟试验离心机振动特性的回归分析

目的 研究试验离心机轴承座以及主轴振动随运行工况的变化规律,实现不同工况下离心机振动的预测。方法 通过试验方法分别获取不同工况下超重力模拟试验离心机的轴承座以及轴振数据。建立试验离心机的单自由度动力学模型,基于该模型,对不同工况下离心机基座振动加速度以及主轴振动位移进行回归分析。结果 离心机轴承座以及主轴振动基频均随着转速以及不平衡量的增大而增大。回归模型对轴承座以及机室基频振动数据的回决定系数均在0.9以上,对中导以及上导主轴振动位移的回归决定系数在0.7左右,对下导主轴振动位移决定系数小于0.1。结论 回归模型可以很好地解释和预测轴承座以及机室振动基频随着转速和不平衡量的变化规律,可以部分预测中导以及上导处主轴振动位移随运行工况的变化。该分析结果为大型试验离心机振动监测系统的设计以及振动特性的预测提供了参考。     

厌氧颗粒污泥流化床的动力学参数测定

介绍了厌氧颗粒污泥流化床反应器的主要动力学参数及其测定方法。通过分批试验测定厌氧动力学系数,以基质代谢平衡方程计算得到颗粒污泥双膜模型中的产甲烷层厚度,进行了颗粒污泥粒径、干密度等的测定和扩散系数的确定。以这些参数为基础的动力学模型计算结果与反应器长期连续运行测定结果相一致,证明了所测参数及其模型的可靠性。      

The consequences of (not) seeing eye-to-eye about the past: The role of supervisor–team fit in past temporal focus for supervisors' leadership behavior

This study seeks to advance our understanding of the leadership consequences that may ensue when supervisors and their teams have similar versus differing orientations toward the past. Integrating a leader–team fit perspective with functional leadership theory, we cast incongruence between supervisor and team past temporal focus as a key antecedent of supervisors' active (i.e., task-oriented and relationship-oriented) and passive (i.e., laissez-faire) leadership behaviors toward the team. We tested our hypotheses in a team-level study that included a field sample of 84 supervisors and their teams using polynomial regression and response surface analyses. Results illustrated that supervisors demonstrated more task-oriented and relationship-oriented leadership when supervisors' and their team's past temporal focus were incongruent rather than aligned. Furthermore, in situations of supervisor–team congruence, supervisors engaged in less task-oriented and relationship-oriented leadership and more laissez-faire leadership with higher (rather than lower) levels of supervisor and team past temporal focus. In sum, these findings support a complex (mis)fit model such that supervisors' attention to the past may hinder their productive leadership behaviors in some team contexts but not in others. Hence, this research advances a novel, multiple-stakeholder perspective on the role of both supervisors' and their team's past temporal focus for important leadership behaviors.     

长径比对管道油气爆炸特性与火焰传播规律影响研究*

为了探究长径比对油气爆炸传播特性与火焰传播规律的影响,为复杂管道受限空间油气爆炸防控提供理论参考,结合油气爆炸与爆炸抑制工程实际需要,构建不同长径比管道油气爆炸模拟实验系统,在此基础上开展不同初始浓度的预混油气-空气混合气爆炸实验。研究结果表明:管道内部的预混油气爆炸超压信号呈先上升后下降的趋势,由于耗散以及憋压效应导致超压下降平稳后仍大于初始压力;同时长径比增加会导致达到最大爆炸超压的油气浓度增加,油气爆炸超压峰值随着长径比的增加呈现上升→下降→上升的规律,小长径比管道的油气爆炸超压峰值高于大长径比管道,但同为小长径比管道或大长径比管道工况的实验结果对比显示爆炸超压峰值随着长径比增加而提升;而超压上升速率则会随着长径比的增加而上升;长径比的增加同时也会促进火焰的加速传播并减小火焰持续时间。     

后藏地区与黄河三角洲典型城市臭氧浓度比较分析

后藏地区典型城市日喀则市和黄河三角洲典型城市东营市的大气首要污染物在2019年5—9月均为臭氧(O₃)。虽然日喀则市O₃超标天数少,但其年平均浓度高于东营市。两地地理气候、产业结构差异巨大,但O₃年均浓度非常接近。对日喀则市和东营市的O₃污染特征进行分析,并探讨O₃污染的影响因素。结果表明:后藏地区紫外辐射强烈,大气环境中O₃的本底浓度值较高;与东营市相比,日喀则市春季O₃浓度最高,全年最高值出现在5月,比东营市早1个月。NO₂对日喀则市O₃的生成影响有限,对东营市O₃的生成影响明显;PM_2.5对日喀则市O₃的生成影响较小,对东营市O₃的生成影响较明显;CO对日喀则市和东营市O₃的生成均有一定影响。超低湿度和长时间日照的气象环境有利于日喀则市O₃浓度的上升,高温、60%～70%的相对湿度和长时间日照的气象环境有利于东营市O₃浓度的上升。     

Impact of Length of Dataset on Streamflow Calibration Parameters and Performance of APEX Model

Due to resource constraints, long‐term monitoring data for calibration and validation of hydrologic and water quality models are rare. As a result, most models are calibrated and, if possible, validated using limited measured data. However, little research has been done to determine the impact of length of available calibration data on model parameterization and performance. The main objective of this study was to evaluate the impact of length of calibration data (LCD) on parameterization and performance of the Agricultural Policy Environmental eXtender model for predicting daily, monthly, and annual streamflow. Long‐term (1984‐2015) measured daily streamflow data from Rock Creek watershed, an agricultural watershed in northern Ohio, were used for this study. Data were divided into five Short (5‐year), two Medium (15‐year), and one Long (25‐year) streamflow calibration data scenarios. All LCD scenarios were calibrated and validated at three time steps: daily, monthly, and annual. Results showed LCD affected the ability of the model to accurately capture temporal variability in simulated streamflow. However, overall average streamflow, water budgets, and crop yields were simulated reasonably well for all LCD scenarios.     

基于电动振动台的强化试验剖面参数计算与控制

在进行组件级产品振动试验时,传统试验方法存在产品的低阶振动模态激发能力较弱,试验结果重现性差,而采用低频特性优良的电动振动台及其控制仪进行应力加载则可克服RS机的缺陷.本文给出了基于电动振动台的随机振动试验剖面的数学描述,推导出应力量级和试验应力谱参数的解析关系,进而导出便于工程应用的剖面参数计算方法,并讨论了应力剖面的控制.最后在某导弹发射控制盒组件的振动强化试验中进行了应用,验证了该方法的有效性.     

故障树分析法及其在导弹故障近似计算中的应用

介绍了故障树分析法的主要分析过程,指出故障树分析法是进行产品设计和系统故障诊断的有效方法,并利用Visual C 语言进行蒙特卡罗仿真,得到了近似计算故障树顶事件发生概率时应选取的最优权因子,最后指出该因子可以用在导弹等特殊设备故障的近似计算中。     

长江流域水环境监控体系配置及其关键参数选择原则

在分析长江流域水质污染现状和自动监控系统的配置现状基础上,针对长江流域需要监控的水域,提出了适合长江流域的国家、省、市三级自动监控体系.最后,提出了水质常规监测站的参数配置原则以及应急监测参数配置原则.     

污水处理厂脱氮效果及相关参数的分析

通过对长沙某污水处理厂进行24 h水质、水量的监测,分析了其Carrousel氧化沟处理污水的特点.从脱氮的原理出发,结合流速、溶解氧等运行参数的考察,发现造成脱氮效果不好的主要原因是沟内缺少厌氧区段,提出改进措施,从宏观改善流体的流动人手,以达到调控溶解氧传递的目的,既而促进微观的硝化与反硝化反应,提高污水处理效果.