关于铁路行车事故预测的应用研究

本文论述了事故预测对铁路行车安全的重要性,并应用灰色预测模型和概率回归估计法模型研制了预测软件,进行铁路行车事故的宏观及微观预测,为采取有针对性的防范措施提供一个可靠信息。     

常温下内循环厌氧反应器的启动研究

研究了内循环厌氧反应器(IC反应器)在常温下处理葡萄糖配水的启动特性。结果表明:在运行温度为25~35℃的条件下,反应器经70 d启动完成,且IC反应器具有较好的处理效果,反应器内能形成大量的颗粒污泥。启动完成后,进水COD浓度在3 000 mg/L左右时,COD去除率一直保持在95%以上,出水COD浓度维持在200 mg/L左右。当HRT为5.8 h,容积负荷为11.9 kg/(m3.d)时,出水VFA低于200 mg/L,产气量为33 L/d,反应器运行正常。     

销轴滑动磨损条件下的极限承载力研究

目的 针对销轴在海洋环境下由于轴向滑动磨损造成的极限承载力变化进行数值模拟研究,得到销轴的极限承载力演变规律,为水下磨损结构的安全评估提供理论依据。方法 首先,运用ANSYS有限元分析软件,建立“柱-瓦”模型进行磨损计算,对滑动磨损方法进行验证。然后,建立实际销轴与锚链横档局部有限元模型,进行磨损分析,得到不同轴向滑动频率下的磨损数据。最后,计算销轴在失效准则下不同磨损深度等级(0、1、2、3 mm)的极限承载力,并根据磨损速度-磨损深度-破断力的映射关系得到其许用极限承载力和累计使用时间随磨损深度的变化曲线。结果 在典型工况(滑动频率为3 Hz)条件下,销轴连续工作约3 298 h,磨损深度可达3 mm,许用极限承载力下降14 180 N。结论 随着销轴轴向滑动频率的增加,销轴的最大磨损深度、总磨损体积、磨损速度均近似呈线性增长变化。在典型工况下,销轴许用极限承载力随着服役时间增长近似呈线性下降,且随着时间增加许用极限承载力下降趋势变缓。     

Global Warming and Global Dioxide Emission: An Empirical Study

In this paper, the dynamic relationship between global surface temperature (global warming) and global carbon dioxide emission (CO₂) is modelled and analyzed by causality and spectral analysis in the time domain and frequency domain, respectively. Historical data of global CO₂emission and global surface temperature anomalies over 129 years from 1860–1988 are used in this study. The causal relationship between the two phenomena is first examined using the Sim and Granger causality test in the time domain after the data series are filtered by ARIMA models. The Granger causal relationship is further scrutinized and confirmed by cross-spectral and multichannel spectral analysis in the frequency domain. The evidence found from both analyses proves that there is a positive causal relationship between the two variables. The time domain analysis suggests that Granger causality exists between global surface temperature and global CO₂emission. Further, CO₂emission causes the change in temperature. The conclusions are further confirmed by the frequency domain analysis, which indicates that the increase in CO₂emission causes climate warming because a high coherence exists between the two variables. Furthermore, it is proved that climate changes happen after an increase in CO₂emission, which confirms that the increase in CO₂emission does cause global warming.     

Window Sensitivity Functions for Line Transect Sampling

L and width 2w, then by a selection of viewing window is meant a choice of w, with the intent being to search for optimal viewing windows, with the goal in mind of improving variances of estimators of population density, reducing sampling effort, while maintaining the property of unbiasedness. The notions of increasing window sensitivity (IWS) and decreasing window sensitivity (DWS) are introduced, and a method of deriving confidence intervals is discussed.     

Evaluation of Different Scales for Measurement of Perceived Physical Strain During Performance of Manual Tasks

The main objective of this study was to evaluate different scales of perceived strain during the performance of various physical tasks. A total of 52 male and female participants took part in 4 experiments to achieve the study objective. The results suggest that a bipolar comfort-discomfort scale is a more appropriate instrument than a discomfort scale for assessing cumulative physical stresses at work, especially at the beginning of the shift. For assessing discomfort at the end of the work shift, a unipolar scale may also be used. On the basis of the obtained results, red, green, and yellow zones are suggested to establish priorities for work redesign efforts in ergonomic control programs.     

混凝沉淀-高级氧化联合处理垃圾转运站污水的实验研究

城市生活垃圾转运站污水具有水质水量变化大、有机污染负荷高、具有强烈恶臭、色度高等显著特点,已成为城市重要的点源污染。为有效消减转运站污水有机负荷,探讨了混凝沉淀-高级氧化联合使用的物化处理方法,考察了联合处理过程中双氧水/亚铁、亚铁投加量、酸化后pH值、混凝剂投加量、中和后pH值等因素对处理效果的影响。小试研究结果表明,在混凝剂投加400 mg/L,亚铁0.06 mol/L,酸化后pH为3,双氧水/亚铁=4∶1,中和后pH为7.5的条件下,污水COD消减量达到60%以上,色度去除率98%,恶臭基本消除。     

耦合装药中扩容半径的理论计算

根据扩容机理,建立了扩容爆破的物理模型,并且根据动量守恒定律得到了不同条件下最终炮孔挤压区域的半径公式.利用这些公式结合炸药和岩石的特性,以及装药参数得到了扩容结果.理论计算结果与试验数据相吻合.这些结果将有助于爆破扩容理论的完善以及该技术发展和推广应用.