安全工程专业英文文献翻译一篇.doc

RIVER WATER QUALITY MODEL NO. 1: III. BIOCHEMICAL SUBMODEL SELECTIONP. Vanrolleghem（University of Kassel, Kurt-Wolters-Str. 3, D-34125 Kassel, Germany）ABSTRACTThe new River Water Quality Model no.1 introduced in the two accompanying papers by Shanahan et al. (2000) and Reichert et al. (2000) is comprehensive. Shanahan et al. (2000) introduced a six-step decision procedure to select the necessary model features for a certain application. This paper specifically addresses one of these steps, i.e. the selection of submodels of the comprehensive biochemical conversion model introduced in Reichert et al. (2000). Specific conditions for inclusion of one or the other conversion process or model component are introduced, as are some general rules that can support the selection. Examples of simplified models are presented.KEYWORDSdenitrification, dissolved oxygen, model selection, water quality models1. INTRODUCTIONThe IWA (formerly IAWQ) Task Group on River Water Quality Modelling was formed to create a scientific and technical base from which to formulate standardised, consistent river water quality models and guidelines for their use. This effort is intended to lead to the development of (a set of) river water quality models that are compatible with the existing IWA Activated Sludge Models (ASM1, ASM2 and ASM3; Henze et al. 1987, Henze et al. 1995, Gujer et al. 1999) and can be straightforwardly linked to them. Specifically, water quality constituents and model state variables characterising C, O, N and P cycling are to be selected for the basic model.In a first effort, the task group analysed the state of the art of river water quality modelling, its problems, and possible future directions (Rauch et al., 1998; Shanahan et al., 1998; Somlydy et al., 1998). This paper is the third of a three-part series series on the development of a model. In the first paper, Shanahan et al.(2000) present the general modelling approach and a six-step decision process is introduced. Reichert et al.(2000) describe in the second paper the equations for the formulation of biochemical conversion processes for a basic river water quality model. This paper gives recommendations for application-specific selection of the biochemical submodel. In addition to these three theoretical papers, two model applications to actual data sets demonstrate the usefulness of the proposed approach (Borchardt and Reichert, 2000; Reichert, 2000).2.CRITERIA FOR THE SELECTION OF THE BIOCHEMICAL SUBMODELSStep 1: Definition of the temporal representation (dynamic versus steady state) of the (sub)models. This step is not only focusing on the transport terms of the model but is also closely linked to the process model. Indeed, this step requires the listing of all characteristic time constants of all relevant processes, including the biochemical processes.Step 2: Selection of the spatial dimensionality. In this step, a decision is to be made on the inclusion of a sediment/sessile compartment in the representation of the river system. At this stage, it is decided whether this compartment has an important impact on the overall river description. Information is required on the relative importance of conversions happening in the bulk liquid and the sediment.Step 3: Determination of the representation of mixing.Step 4: Determination of the representation of advection. Compared to Steps 1 and 2, the decisions in Steps 3 and 4 do not depend on the characteristics of the conversion processes.Step 5: Selection of the biochemical submodels (see below in detail).Step 6: Definition of the boundary conditions. Depending on the model compartmentalization, certain biochemical processes may be represented as boundary conditions (typically boundary fluxes). In these instances, boundary terms may replace one or more biochemical submodels.In the overall decision process of a water quality modelling exercise summarised above, step 5 forms a fundamental part. Indeed, in this step it is determined which components and processes are to be included in the model and which ones can be omitted. In terms of Equation 1, this step determines the elements in the concentration vector, c, and the expressions to be included in the reaction vector, r(c,p). We propose that this step be completed within the framework of the Peterson stoichiometry matrix as presented by Table 1 in Reichert et al. (2000). The step in fact requires several decisions concerning specific model components and processes. These are delineated in the following.Compartments. One of the most important decisions in terms of submodel selection is of course the decision whether it is necessary to consider one or more compartments in which the reactions summarised in the process matrix are occurring. In case one decides for more compartments, the number of state variables in the models is increased substantially, leading to considerably longer calculation times.The most complete model would contain all state variables in the water column, particulate state variables attached to the surface of the river bed (interacting with dissolved compounds in the water column), all state variables in the sediment pore volume, and, finally, particulate state variables attached to sediment particles. In case the sediment is modelled as a biofilm then the number of state variables is increased even more. Also in the case of the selection of several compartments, simplifications to such a complicated model will often be appropriate. In the following, we discuss adequate models for typical situations.3.EXAMPLES OF SUBMODEL SELECTIONIn the following, some examples are presented that illustrate how simplifications of the basic River Water Quality Model no. 1 can be obtained for adequate description of particular situations in rivers.In Table 2, a simplified model is introduced in which the influences of consumers, pH-variations and phosphorus adsorption/desorption on other variables in the system can be assumed to be negligible and their variation itself is of no interest to the model builder. This model may be selected in case pH measurements indicate only slight variations thereof, when phosphate is not the limiting nutrient, and when measurements indicating the activity of consumers are not available or not sufficiently convincing to extend the model with this state variable and the corresponding processes.4.CONCLUSIONThe River Water Quality Model no.1 presented in Reichert et al. (2000) is discussed in this paper. It can under various circumstances be simplified as demonstrated. Guidelines on the choice of different submodels that can be selected from the multitude of biochemical process equations presented in Reichert et al. (2000) have been given. There are no clear cut decision criteria for the conversion part of the model, but guidelines have been presented and some general rules for model selection specified.REFERENCESBorchardt D. and Reichert P. (2000) River Water Quality Model No. 1: Case study II.Sediment oxygen demand in the river Lahn,submitted to the 1st World Congress of the IWA, Paris 2000 for publication in Wat. Sci. TechBrown L.C. and Barnwell T.O. (1987). The enhanced stream water quality models QUAL2E and QUAL2E-UNCAS:Documentation and User Manual, Report EPA/600/3-87/007, U.S. EPA, Athens, GA, USA.Gujer W., Henze M., Mino T. and van Loosdrecht M. (1999) Activated Sludge Model No. 3, Wat. Sci. Tech. 39(1), 183-193.矿业中的事故分析在大约50多个国家，煤都是产自于地下矿井。地下煤矿种类很多，有使用最新远程控制设备的现代化煤矿，由一小部分技术高超的工作人员操作，这要得益于对工作场所状况的所有方面的持续监测；也有手工挖掘的煤矿，在这里煤要靠手工来开采和运输，因此经常处于不安全和不健康的状况中。就工作人员的安全和健康而言，地下煤矿的开采是历史上最具危险性的活动之一。幸运的是，由于新技术、大量的资金投入、集中持续的培训，以及煤炭产业链中所有阶段对安全健康的态度的转变，使得煤矿开采中的职业安全和健康取得了显著持续的改善。但是，如果一个包括了一些关键检查和协调的安全网络，没有在适当的地方评估和控制危险源，那么，事故、不健康因素和疾病就会发生。这些被论述如下：一、岩石冒落。地下煤矿频繁遭遇塌方，导致从死亡和受伤到停产等各种结果。地下开采仍然是美国有最高致命伤害率的产业之一，和其它产业相比，是全国平均水平的五倍多。在1996-1998年期间，近一半的地下死亡事故归因于矿顶、矿柱和采矿工作面的塌陷，每年锚杆间小块岩石的冒落使500-600名矿井工人受伤。几个因素促使了地下煤矿塌方的发生，如：地质原因、应力状态、矿井布局和矿井环境。在影响煤矿塌方危险事件的因素中，应力状态和布局可被恰当的矿井设计稍加控制。但是，控制塌方中地质条件的影响是相对更难的，因为地质条件属于自然的不确定性，所以它们在塌方的发生中构成了内在的易变性。因此，为了处理与塌方相关的不确定因素，风险评估办法被要求用于减少塌方危险事件导致的后果和相关损失。二、突出。人们认识气体和岩块突出的自然现象已经很长时间了，如火山爆发、间歇泉，以及含饱和二氧化碳的水脱离火山口上的贮水池而爆发。由于采矿活动扰乱了岩石块里物质进行相变的平衡，岩石和气体的突出就可能发生，煤矿里的这种事件已经被记录150多年了。人们做出各种尝试来给出一个对这些过程充分合理的解释，二战后突出事件的持续频繁仍需要更多广泛的研究。在过去的十年里，由于高产量和向更深煤层开采的趋势，煤和瓦斯的突出问题被显著加重了。但是，尽管付出了巨大努力，奇怪的是对突出机理的研究没有取得一点进步。预测技术依然不可信赖，不可预料的突出事件对于煤矿来说仍然是一个主要的问题。在中国，突出事件出现在一些煤田和大量的煤矿中。实际上，中国记录了最大数量的突出事件。发生突出事件的最重要的煤田位于以下地区：陕西（阳泉），辽宁（北票），河南（焦作），重庆（潼南和松藻），河北（开滦）。在中国，煤和瓦斯的突出被区分为以下四种类型：l 无瓦斯的煤爆炸l 瓦斯爆炸l 煤和瓦斯的突出l 岩石和瓦斯的突出三、矿井火灾。火的产生有三个必要的要素，它们是燃料、氧气、着火点，被称作起火三角。煤层构成了起火三角的三分之一，它含有固体和气体燃料的自然沉淀。矿井通风携带氧气起火三角的第二个要素，贯穿了整个矿井。构成起火三角的第三个要素是着火根源，遍布于整个矿井，如：电机、设备、灯光、电站、电路系统、柴油设备、传送带摩擦的源头、焊接、氧乙炔焰切割，以及其他生产者的摩擦、火花和火焰。为了阻止煤矿火灾的发生，有必要采取一些关键的防范措施、检查和协调措施。就矿井工人的安全和健康来看，火是一个显著的危险源。地下矿井和地表矿山的火使我们民族矿工的生命和生活处于危险之中。地下矿井的通风流动可携带烟和有毒的燃烧产物，贯穿整个矿井，使通过数英里长的狭窄通道的逃生变得艰难、耗时。由于无限的燃料提供和易燃甲烷气体的存在，地下煤矿的火就尤其危险。美国最大的矿火灾难发生在1909年11月，美国伊利诺斯州樱桃煤矿，在这场灾难中有259个矿工失去了生命。在1990-2001年期间，超过975次见诸报道的火灾发生在美国矿业，导致了470多人受伤、6人死亡，以及几座矿的暂时关闭。超过95%的火灾发生在地下煤矿，矿井火灾的主要原因包括火焰切割、焊接操作、摩擦、短路、移动设备故障和自燃。在保护23万多矿工的生命和生计中，预防、早期可靠的发觉、控制和矿井火灾的阻止是关键的因素。四、爆炸。虽然在煤矿中预防爆炸已取得了很大进步，但爆炸依旧发生，有时会出现多人死亡。爆炸和由此产生的大火常常杀死工人或使他们陷入困境，阻塞逃生的通道，并且迅速产生使人窒息的气体，使地下工作的每个工人都感到害怕。地下煤矿的爆炸是在有着火源存在的情况下，易燃气体和混合着空气的可燃粉尘不断积累引起的。预防爆炸的方法有好几种，如：通过甲烷排放和通风使甲烷的浓度达到最小，添加充足的岩石尘土使煤粉尘失效，以及消除着火源。