Ignition characteristics, conditions of criticality and disappearance of criticality of cumene hydroperoxide reaction by modeling approach

The thermal explosion problem of cumene hydroperoxide exothermic reaction which is used in chemical industries for production of some chemical materials is investigated. The analytical solutions of the problem to determine the margin between ignition and non-ignition systems are presented. The solution offers different analytical expressions which relate between the critical parameters for both steady and unsteady-states in different planes of solutions for different cases. The numerical solutions in different planes offer different trajectories of solution as sub-critical (non-ignition) and supercritical (ignition). Also from the numerical solution the relations between the critical parameters are presented. The critical behaviors from both analytical and numerical solutions are concise and pertained the same results.     

Optimal control of distillation column using Non-Dominated Sorting Genetic Algorithm-II

Many control problems involve simultaneous optimization of multiple performance measures that are often non-commensurable and competing with each other. The presence of multiple objectives in a problem usually gives rise to one set of optimal solutions, largely known as Pareto-optimal solutions. In this paper, the Non-Dominated Sorting Genetic Algorithm-II (NSGA-II) has been successfully applied to optimization of dynamic state of simple distillation process. This paper presents the tuning of Proportional-Integral-Derivative (PID) controllers by minimizing of three objective functions (overshoot, response time, and Integral of Absolute Error (IAE)) through NSGA-II. A MATLAB code for real-parameter NSGA-II has been coupled with HYSYS v.3.1 process simulator for simulation and optimization of process. Optimization numerical results show that genetic algorithm is more suitable method for optimal control of distillation columns than traditional methods.     

铁路交通安全培训“六要素”探讨

结合铁路交通安全的严峻形势,对铁路交通安全培训的＂5W1H＂六要素进行了初步的分析。＂5W1H＂包括原因（WHY）、内容（WHAT）、地点（WHERE）、时间（WHEN）、人员（WHO）、方法（HOW）这六个方面,本文对铁路交通安全培训的政策背景（即原因）、内容、地点、时间、人员和实施方法进行分析,回答这六个方面的问题,寻求合理可行的解决措施,并以此形成有效的铁路交通安全培训模式。     

A simple,explicit formula for the critical pressure of homogenous two-phase nozzle flows

The critical pressure ratio of the homogeneous two-phase nozzle flow model known as the Omega method is expressed in function of the Omega Parameter as the exact numerical solution of a transcendental equation. A well fitting, easy to use, explicit approximation for flashing and non-flashing flows is presented here. The validation against the exact numerical solution proves that this new formula is better fitting than the other ones in the technical literature for both single and two-component flows.     

危险品道路运输多目标路径优化方法研究

道路危险品运输路径优化是提高危险品运输安全的一项重要措施。通过对国内外文献的分析研究，本文提出了危险品道路运输路径优化的数学模型，该模型首先求出单项目标的最优解，然后找出每项目标的实际值尽可能接近各自单项的最优值。本文也建立了包括路线长度、时间、费用、路线风险、敏感目标人数在内的危险品道路运输目标体系，并给出危险品运输路线选择决策的程序，为政府相关部门进行路线选择提供决策依据。     

“If I know when you will arrive,I will let you walk to school:” The role of information technology

Introduction: Providing a sense of supervision for parents may facilitate their children’s involvement in physical outdoor activities, such as walking to school. Information technology (IT) solutions could bring more parental supervision, which in turn has the potential to enhance the proportion of walking trips to school. This study aimed to examine the role of a proposed hypothetical IT solution that gives parents real-time information about children’s entrance to and exit from the school, for the intention of parents letting their children walk to school. Method: A total of 820 questionnaires were distributed among pupils aged 7–9-years across 28 elementary schools to be completed by their parents (82% return rate). Results: Compared to the group of walking pupils, increased parental intention to let their children walk to school under the proposed solution could be explained by considerably more variables in the group of pupils who did not walk to school. The findings revealed that increased parental intention was higher among the walking pupils compared to the non-walking pupils. For the non-walking pupils, enhancement of walking facilities across the school area could potentiate the use of the proposed solution by the parents, which in turn may increase the proportion of walking on school trips. In addition, boy pupils, the pupils whose parents evaluated walking more favorable, those from lower socioeconomic backgrounds, and those living in close proximity to the school could more likely benefit by shifting from non-walking to walking modes of travel, after implementation of the solution.     

基于犹豫直觉模糊集-TOPSIS的危险品多式联运风险评估

为了对危险品的多式联运系统风险进行评估,首先在"人、机、管、环"4M理论的基础上,将多式联运中"转运"这一特殊流程考虑进去,以"人、机、管、环、转运"这5个因素作为决策问题中的属性;其次,采用犹豫直觉模糊语言集为决策者的初始决策矩阵赋值,并利用均值-标准差的汉明距离来衡量两个犹豫直觉模糊语言数之间的距离;然后,以危险品多式联运系统中的风险为标准,采用基于犹豫直觉模糊语言集的TOPSIS方法进行不同方案的决策。最后,以磷酸在宜昌-衢州之间的运输为案例,对4种常用运输方案进行风险评估,以综合评价指数进行对比。结果表明,在先水路后铁路、先水路后公路、先公路后铁路、先铁路后公路4种方案中,从宜昌到衢州之间先公路后铁路的运输方式所得综合评价值最高,应选择方案3。     

Decentralized scheme for leaks’ location in a branched pipeline

This article presents a novel scheme for the detection and isolation of single leaks in a pipeline with a branch junction by measuring only the flow rate and pressure at the ends of the line. For the solution of this realistic issue, which commonly occurs in pipeline networks, the position of the branch junction and its flow rate are supposed to be known. The idea consists of deriving a model considering the branch junction as a known point in the pipeline such that the leak position is characterized by two possible orientations with respect to the branch (upstream and downstream of it). Thus, this model allows proposing a diagnosis scheme which includes a static selector and two identifiers designed by using a continuous extended Kalman filter with only one deviation parameter to be estimated. This framework reduces the identification task to one parameter which is associated with the deviation from a prescribed positive base position located between one of the pipeline ends and the branch. Simulation and experimental results with data of a hydraulic pilot pipeline of 200 [m] show the promise of the novel scheme.     

管道内可燃物爆炸问题现状与研究方向

文章首先对问题进行提炼,然后从机理、试验两个方面就研究现状做了综述,结语部分指出了进步的研究方向。     

Economic assessment of human errors in manufacturing environment

Traditional human reliability assessment techniques and accounting system cannot directly provide loss information for assessing the impacts of human errors. This obstacles force industrial managers to justify the proper accident and injury prevention process through their experiences. The efficiency and effectiveness of the system safety barriers are in doubt and the smooth operation of manufacturing activities are insecure. In this study, a human error cost estimation model is introduced to facilitate line managers with a proper tool to collect and calculate the total losses of its impact. Experts’ judgments and pair wise comparison technique are incorporated to interrogate managers’ knowledge of human errors and correspondent costs. This approach can overcome the problem of insufficient cost information caused by current accounting system and compensate the influence of safety and health department due to the low organizational status in quo. Although the cost figures may not represent exact amount of losses, the percentage of each cost factor in terms of department operation budget gives the managers a practical way for justifying how the resources should be allocated.     

How to treat expert judgment? With certainty it contains uncertainty!

To be acceptably safe one must identify the risks one is exposed to and decide what risk reducing measures are required. It is uncertain whether the threat really will materialize, but determining the size and probability of the risk is also full of uncertainty. When performing an analysis and preparing for decision making under uncertainty, quite frequently failure rate data, information on consequence severity or on a probability value, yes, even on the possibility that an event can or cannot occur, is lacking. In those cases, a possible way and sometimes the only way to proceed is to revert to expert judgment. Even in case historical data is available, an expert can be asked whether and to what extent such data still hold in the current situation.Anyhow, expert elicitation comes with an uncertainty depending on the expert's reliability, which becomes very visible when two or more experts give different answers or even conflicting answers. This is not a new problem, and very bright minds have thought how to tackle this in a rational and objective way. But so far, however, the topic has not been given much attention in daily process safety and risk assessment practice. Therefore, this paper has a review and applied character and will present various approaches with detailed explanation and examples.     

基于Dijkstra算法的乡镇消防站选址问题

在规划时,影响消防站设置的因素很多,最短路径问题是消防站选址的关键内容。主要讨论了基于Dijkstra算法在广大农村辖区内合理的进行乡镇消防站选址的问题,简述了Dijkstra算法在乡镇消防站选址中的应用思路,并通过解决实际问题论证了这种方法的可行性和实用性。在解决实际问题中将各乡镇的交通网络图等效为带权的拓扑结构图,将消防站和各乡镇转化为图上的各个顶点,得出消防站节点到所有节点的最短路径（最短耗时）,然后根据实际需要来选择我们所需的路径和节点并建立合理的消防站。该方法为乡镇消防站选址的综合解决方案创造了有利条件,对于广大农村辖区的乡镇消防站选址提供了好的思路。     

吸水性还原性材料对煤自燃影响的实验研究

为了解决吸水性盐和还原性材料仅依靠其单一特性抑制煤自燃而抑制效果并不理想的问题,提出了利用羟甲基磺酸钠的吸水性和还原性来抑制煤自燃。将原煤-20%羟甲基磺酸钠通过对比原煤、原煤-20%MgCl2和原煤-20%VC,利用程序升温实验和FTIR测试来研究其抑制煤自燃的效果。研究结果表明:3种溶液处理煤均在一定程度上抑制了煤自燃,其中,20%羟甲基磺酸钠溶液对抑制煤低温氧化的效果最好,经过其处理的煤样表观活化能最大,同时,依靠其还原性很好地保护了煤中的亚甲基和羟基不被破坏,抑制煤自燃效果明显优于20%MgCl2溶液和20%VC溶液。     

Analysis of work related accidents in the Spanish mining sector from 1982-2006

Introduction

The rate for work related accidents in the Spanish mining sector is notably higher than in other countries such as the United States. It produces a very negative impact on the mining industry. This paper is the report of a study on serious and fatal accidents in Spanish mining from 1982-2006. It is based on the reports of 212 accidents (serious or fatal) carried out by the General Management of Energy and Mining of Catalonia (Spain). Method: The high work-related accident rate in the Spanish mining sector makes it necessary to carry out an analysis and research that can shed light on the causes of this high rate; this is the only way that a solution can be found. The study is based on Feyer and Williamson's analysis of accident causes, as they apply to 212 accidents. The types and causes of the accidents are coded according to the coding system used by the Spanish National Institute for Safety and Hygiene in the Workplace, which allows us to identify a series of direct causes and contributing factors in different accidents. Results If all the causes and factors that are present in the accidents are known, we are able to look for appropriate solutions to reduce them as much as possible. In short, we are able to come up with a series of conclusions that expose the weak links in the management of accident prevention in companies. This is helpful in the struggle to reduce work injuries in the Spanish mining sector.     

An application of 3D gasdynamic modeling for the prediction of overpressures in vented enclosures

A three-dimensional gasdynamic model with constant burning rate is applied for the prediction of the maximum pressure rise from gaseous combustion in vented enclosures. A series of calculations for an enclosure with aspect ratio close to unity are presented. Both cases with and without obstacles in the enclosure are considered. Results of calculations are compared with a simple 0D solution for spherical vessels. It is shown that, in cases without obstacles, the 0D solution for the maximum reduced overpressures is close to the predictions of the detailed modeling. In cases with obstacles, the detailed simulation gives significantly higher overpressures than those from the 0D model. However, in all the cases the reduced pressures are correlated well with the maximum flame surface area.     

三棱钻杆粉体负载扭矩计算模型研究

为了实现三棱钻杆转动过程的定量化计算,在分析了三棱钻杆排粉机理的基础上,提出了基本假设,建立了扭矩基本物理模型,并阐述了物理模型的求解过程,得到了基本参数的解析解。在此基础上,对相关参数的求取方法以及最小扭矩问题进行了分析讨论,求得了钻孔内煤粉密度ρ的解析解以及降低钻杆整体扭矩的方法,提出了实际应用环节测定临界转速w界的实验方法,并得到了提高钻孔长度的理论方法。     

Critical and transition conditions of gaseous explosion

The critical and transition conditions of a gaseous explosion at constant pressure and varying pressure is investigated. The study covered the solutions of the problem in pressure-time plane, temperature-time plane, as well as pressure-temperature plane. The explosion characteristics of combustible gases using the definition of criticality as an inflection point in critical trajectory. as well as other definitions of criticality are presented. The analytical study showed that the critical parameters for constant pressure explosion are lower than those for constant volumes where θ¹_tr is lowered from 0.5 to 0.29 and θ_atr is also lowered from 0.25 to 0.17. The sensitivity of the critical pressure to the ambient temperature and the boundary between ignition and non-ignition regions are also offered. It was also found that the critical parameters in the temperature–pressure plane were different from those obtained in the temperature-time plane or the pressure–time plane.     

危险货物多式联运路径优化问题的多目标优化算法

为了更为有效地规划与管理危险货物运输,研究在多式联运危险货物时的路径优化问题,同时囊括双目标、多批货物以及货物的送达时间要求和路段的容量限制。以运输和转运过程中的总成本和总风险最小为目标,构建了双目标0-1线性规划模型。集成路径搜索算法和非支配排序规则,设计了基于帕累托分析的多目标优化算法,以获得原问题的非劣路径。算例结果表明,该算法可有效地获得实际问题的一组具有竞争性的非劣解,且相比于单式运输,多式联运危险货物有望同时降低总成本和总风险。     

Recovery of methyl orange and Congo red from aqueous solutions using tri-octyl amine (TOA) in benzene as carrier

The recovery of anionic azo dyes namely Congo red (CR), methyl orange (MO) from acidic aqueous solutions using tri-octyl amine (TOA) as an extractant has been investigated. The percentage of extraction of MO and CR increases with an increasing TOA concentration. The anionic dyes were extracted from aqueous solution at pH 2.0 ± 0.1. The extracted dye has been back extracted into aqueous solutions using sodium hydroxide, sodium carbonate and sodium bicarbonate. The organic phase obtained after the stripping of dyes was washed with dilute sodium hydroxide solution to neutralize any sulphuric acid trapped or adhered to the solvent and then with distilled water. This solvent was reused in succeeding extraction of dyes. The influencing parameters were; the effect of diluents, effect of extractant concentration, effect of pH, effect of interference study, effect of equilibrium time, various stripping reagents and stripping phase ratio. The characterization studies such as UV and IR spectra of extracted and stripped MO and CR was also studied.     

Modelling bund overtopping using a shallow water CFD model

This paper describes the development of a model for assessing the hazards arising from liquid spills from storage tanks containing flammable liquids. The model is based on computational fluid dynamics (CFD) solutions to the shallow water equations and is able to account for the interaction of a liquid spill with sloping ground and walls/bunds. These features mean that it has a much wider range of applicability than simple models and yet, as it is based on the solution to the two-dimensional shallow water equations, is relatively quick to run. The key parameter of interest in risk assessments is the fraction of a tank contents that would overtop the surrounding wall/bund that has been designed to retain it. A simple ‘sub-model’ has been developed to take account of this three-dimensional phenomenon within the two-dimensional model. The numerical solution of the shallow water equations is obtained through an adaptive method using two shock-capturing numerical techniques; the weighted average flux (WAF) and random choice methods (RCM). These provide a robust solution algorithm. A simple test case has been used to demonstrate the applicability of the model.