突变理论在矿山安全中的应用

矿山企业的安全状况，直接关系到我国资源工业的发展，如何提高矿山安全，是矿山重大危险源辨识与评价技术研究的重点。笔者应用突变理论这一工具，对矿井内因火灾、矿山安全投资、煤层注水效果进行研究，其中的结论可服务于生产实际     

A methodology for optimal MSW management,with an application in the waste transportation of Attica Region,Greece

The paper describes a software system capable of formulating alternative optimal Municipal Solid Wastes (MSWs) management plans, each of which meets a set of constraints that may reflect selected objections and/or wishes of local communities. The objective function to be minimized in each plan is the sum of the annualized capital investment and annual operating cost of all transportation, treatment and final disposal operations involved, taking into consideration the possible income from the sale of products and any other financial incentives or disincentives that may exist. For each plan formulated, the system generates several reports that define the plan, analyze its cost elements and yield an indicative profile of selected types of installations, as well as data files that facilitate the geographic representation of the optimal solution in maps through the use of GIS. A number of these reports compare the technical and economic data from all scenarios considered at the study area, municipality and installation level constituting in effect sensitivity analysis. The generation of alternative plans offers local authorities the opportunity of choice and the results of the sensitivity analysis allow them to choose wisely and with consensus.The paper presents also an application of this software system in the capital Region of Attica in Greece, for the purpose of developing an optimal waste transportation system in line with its approved waste management plan. The formulated plan was able to: (a) serve 113 Municipalities and Communities that generate nearly 2 million t/y of comingled MSW with distinctly different waste collection patterns, (b) take into consideration several existing waste transfer stations (WTS) and optimize their use within the overall plan, (c) select the most appropriate sites among the potentially suitable (new and in use) ones, (d) generate the optimal profile of each WTS proposed, and (e) perform sensitivity analysis so as to define the impact of selected sets of constraints (limitations in the availability of sites and in the capacity of their installations) on the design and cost of the ensuing optimal waste transfer system. The results show that optimal planning offers significant economic savings to municipalities, while reducing at the same time the present levels of traffic, fuel consumptions and air emissions in the congested Athens basin.     

Linking 3D spatial models of fuels and fire: Effects of spatial heterogeneity on fire behavior

Crown fire endangers fire fighters and can have severe ecological consequences. Prediction of fire behavior in tree crowns is essential to informed decisions in fire management. Current methods used in fire management do not address variability in crown fuels. New mechanistic physics-based fire models address convective heat transfer with computational fluid dynamics (CFD) and can be used to model fire in heterogeneous crown fuels. However, the potential impacts of variability in crown fuels on fire behavior have not yet been explored. In this study we describe a new model, FUEL3D, which incorporates the pipe model theory (PMT) and a simple 3D recursive branching approach to model the distribution of fuel within individual tree crowns. FUEL3D uses forest inventory data as inputs, and stochastically retains geometric variability observed in field data. We investigate the effects of crown fuel heterogeneity on fire behavior with a CFD fire model by simulating fire under a homogeneous tree crown and a heterogeneous tree crown modeled with FUEL3D, using two different levels of surface fire intensity. Model output is used to estimate the probability of tree mortality, linking fire behavior and fire effects at the scale of an individual tree. We discovered that variability within a tree crown altered the timing, magnitude and dynamics of how fire burned through the crown; effects varied with surface fire intensity. In the lower surface fire intensity case, the heterogeneous tree crown barely ignited and would likely survive, while the homogeneous tree had nearly 80% fuel consumption and an order of magnitude difference in total net radiative heat transfer. In the higher surface fire intensity case, both cases burned readily. Differences for the homogeneous tree between the two surface fire intensity cases were minimal but were dramatic for the heterogeneous tree. These results suggest that heterogeneity within the crown causes more conditional, threshold-like interactions with fire. We conclude with discussion of implications for fire behavior modeling and fire ecology.     

Of discovery and dread: The importance of work challenges for international business travelers' thriving and global role turnover intentions

As frequent travel across international borders has become common for an ever-increasing number of workers, it is essential to understand what helps these international business travelers (IBTs) thrive and embrace their global work responsibilities. This study's purpose is to examine the role of developmental opportunities (i.e., work role challenges) in helping IBTs see frequent travel as a predominantly beneficial experience. By integrating two theories of motivation—conservation of resources theory and the challenge-hindrance demands framework—I build a moderated mediation model of IBTs' intent to cease their global work responsibilities (i.e., global role turnover intentions). Using latent moderated structural equation modeling, I test the model on a sample of 204 IBTs collected at two time points. Results show that, through the psychological state of thriving at work, travel frequency has a negative indirect association with IBTs' global role turnover intentions when IBTs' work roles are challenging and a positive association when their work lacks challenge. This is primarily the case regarding the challenge of being responsible for others at work. The novelty of IBTs' work tasks is also a salient challenge but to a lesser extent. This study contributes to literatures on global work, work role design, and thriving.     

Risk assessment of chemical process considering dynamic probability of near misses based on Bayesian theory and event tree analysis

With the development of modern automatic control systems, chemical accidents are of low frequency in most chemical plants, but once an accident happens, it often causes serious consequences. Near-misses are the precursor of accidents. As the process progresses, near misses caused by abnormal fluctuation of process variables may eventually lead to accidents. However, variables that may lead to serious consequences in the production process cannot update the risk in the life cycle of the process by traditional risk assessment methods, which do not pay enough attention to the near misses. Therefore, this paper proposed a new method based on Bayesian theory to dynamically update the probability of key variables associated with process failure risk and obtain the risk change of the near-misses. This article outlines the proposed approach and uses a chemical process of styrene production to demonstrate the application. In this chemical process, the key variables include flow rate, liquid level, pressure and temperature. In order to study the dynamic risk of the chemical process with consideration of near misses, according to the accumulated data of process variables, firstly the abnormal probability of the variables and the failure rate of safety systems associated with the variables were updated with time based on Bayesian theory. On the basis of the dynamic probability of key process variables, an event tree of possible consequences caused by variable anomalies was established. From the logical relationship of the event tree, the probability of different consequences can be obtained. The results show that the proposed risk assessment method based on Bayesian theory can overcome the shortcomings of traditional analysis methods. It shows the dynamic characteristics of the probability of different near misses, and achieves the dynamic risk analysis of chemical process accidents.     

When work is wanted after hours: Testing weekly stress of information communication technology demands using boundary theory

Information communication technologies (ICTs; e.g., smartphones) enable employees to work anywhere and anytime, blurring work and family boundaries. Building on this trend, this study draws from work–family border/boundary theory to examine antecedents and consequences of employees' weekly experiences of ICT demands (i.e., being accessible and contacted for work after hours via ICTs). A sample of 546 elementary teachers completed a registration survey and a weekly diary for 5 weeks. Multilevel modeling results suggest that ICT demands as a form of work intrusion in the home can constitute a source of significant weekly strain (i.e., negative rumination, negative affect, and insomnia). As border crossers, teachers' adoption of a technological boundary tactic (i.e., keeping work email alerts turned off on mobile phones) was related to lower weekly ICT demands. As important border keepers at work, school principals' work–family support was related to teachers' lower weekly ICT demands, whereas parents' after-hours boundary expectations were related to teachers' higher weekly ICT demands. Moreover, teachers' boundary control was found as a mediating mechanism by which the two border keepers influenced teachers' ICT demands−negative rumination link. That is, teachers who received fewer boundary expectations and/or more work–family support had greater boundary control, which in turn buffered the ICT demands–negative rumination relationship.     

基于轴—辐理论的皖江城市带物流网络空间构建

大力发展现代物流业和皖江城市带承接产业转移示范区建设是两大重要国家级战略.首先对轴—辐理论的国内外研究现状进行了总结和归纳,分析了轴—辐网络的结构及其优劣势.其次,设计了物流中心性指数的评价指标体系,运用主成分分析法对皖江城市带的9个地级城市进行物流节点等级划分,根据分析结果的总得分和区位特征确定合肥、芜湖、安庆3个一级物流节点,形成轴三角.分析了各级物流节点间的干线及支线物流通道,构建了皖江城市带轴—辐物流网络空间.     

生物法废气净化专用微生物菌种及其作用

用气相培育驯化法培养获得废气净化专用菌种,由其挂膜制作的生物膜填料塔对废气中甲苯进行净化,实验结果表明,气相培养法所得菌种对甲苯的净化性能明显优于液相培养法所得菌种.生物膜通过吸附-生物降解作用过程净化气相中的甲苯,使针对挥发性有机废气生物净化过程提出的吸附-生物膜动力学理论的依据得到了验证.     

西部大开发中的生态安全问题

正确处理区域发展与生态安全是西部开发战略的关键。以可持续发展为目标的区域空间结构理论 ,分析了在新一轮科技革命和产业革命的新形势下推动区域发展和区域空间结构演变的决定性因素 ,以及实行效益原则与社会公平原则相统一的必要性 ,从中引出西部大开发中确保生态安全的极端重要性。并就实现区域发展与生态安全的双赢目标所必须建立的能力体系和制度体系提出了建议。      

生态工业园区水资源梯级利用的博弈分析

水资源是生态工业园区中最重要的资源之一,模拟自然生态系统,园区中的水资源用户也可根据功能的不同分为生产者、消费者和分解者.由于供给量的限制和国家的排污政策逐渐趋紧,生态工业园区中水资源数量和质量的分配存在利益冲突的问题,矛盾日渐凸现.本文试图运用博弈论的方法,构建一个水资源管理的梯级利用模式,探讨生态工业园区内水质要求不同的企业间如何实现水资源的合理分配,使之既符合企业的需要,又符合整个园区的供给限制,同时对环境的损害最小.之后从微观经济学的角度对各利益主体参与水资源梯级利用的动因和积极性进行了经济学上的分析,得出生态工业园区中水资源梯级利用体系能否达成“物尽其用、废物最小化”的目标,取决于不同利益者的博弈结果.水资源价格和排污收费价格的提高,可以减少新鲜水资源的购买量和最终的排污量,有利于促进园区内企业间的水资源梯级利用；而梯级利用的过程,也是各级消费者之间的一场博弈,博弈结果将决定再生水资源的售出价格.