ON THE CAPACITY-EXPANSION OF DESALINATION PLANTS AND STORAGE TANKS1

ABSTRACT A mathematical programming model is structured to find the optimal time and capacity expansion path of desalination plants and storage tanks for a hypothetical community which depends on desalination as its sole, or major, water supply source. The objective is to determine the least costly combination of sues and times of installation (of both desalting plants and storage tanks) which can meet a rising water demand over a finite planning horizon. The optimality criterion used in the model is based on two major economic elements: the economies of scale inherent in such facilities and the time-value of money represented by the interest rate, the former favoring large capacities and the latter small capacities. The model is applied using three population growth patterns and two interest rates. The water demand components for every year in the planning period are computed using empirical formulas which are based on population and other basic data. The model is solved for each of the above cases with the aid of a computer program based on the method of feasible conjugate directions. The results clearly reflect the balance between the economies of scale and the time-value of money under every demand growth function.     

考虑液固耦合储液罐非线性地震反应分析

利用ADINA有限元软件研究了考虑液固耦合的立式圆筒形锚固储液罐非线性地震反应.通过分析计算1000m3储液罐自振特性,储液罐的加速度峰值沿罐壁高度变化趋势,罐壁的应力分布等反应,初步揭示其破坏机理,分析结果为储液罐的抗震设计提供重要的参考依据.     

声发射在油田常压储罐检测中的应用

介绍了声发射检测技术的基本原理和特点,针对油田在用常压储罐检验存在的问题,应用德国VALLENAMSY-5声发射仪对油田在用的常压储罐罐底进行了检测,对现场检验情况和实测数据进行分析,根据现场检验存在的问题,提出了常压储罐声发射检测研究的下一步工作打算。     

The trouble with tanks: unsettling dominant Australian urban water management paradigms

Over the course of Australia's Millennium Drought, urban water managers gained more appreciation of householders' willingness and capacities to respond to water shortages and restrictions, including by installing rainwater tanks (RWTs) for watering gardens. How urban water managers regard tanks and tank users gives insight into their understandings of social sustainability, as found in interviews conducted in 2006 and 2010. These also revealed a growing distance between policymakers and water providers pursuing a broader approach to sustainability in their communities. The RWT is considered here as a limit case for paradigms of urban water management: it challenges conventional distinctions (such as provider/consumer) and heralds a new hydropolitics. These challenges are discussed as seven kinds of trouble with tanks: (1) incompatibility with the management model and vision of modernity enshrined in the ideal of centralised provision in control of accredited water experts; (2) anxieties about control and risk aroused by these private on-site facilities and their non-expert users; (3) equivocation over their environmental effects, normally assessed in hydrological terms that downplay the benefits of green streetscapes; (4) inexplicability of their popularity within dominant economically rationalist models of customers; (5) educational effects that exceed rationalist, individualist models of learning and require more socially realistic, culturally intelligent and practice-oriented approaches; (6) generation of enthusiasms that are spurned as threats to rationality instead of harnessed to energise the sustainability journey and (7) community-building effects that are unthinkable within the neoliberal customer paradigm but graspable to water managers through lay concepts like “dinner table conversations”.     

Seismic risk assessment of liquid overtopping in a steel storage tank equipped with a single deck floating roof

Major earthquakes have demonstrated that Natech events can be triggered by liquid overtopping in liquid storage tanks equipped with floating roofs. Thus, research on the dynamic behaviour of steel storage tanks with floating roofs is still required. In this paper, the seismic risk against liquid overtopping in a real steel storage tank with a floating roof was analysed using a simplified model that was validated by a refined finite element model based on the arbitrary Lagrangian-Eulerian approach. The simplified model utilizes the Lagrangian of a floating roof-fluid system and is capable of providing a response history of the floating roof. It was demonstrated that it could predict the maximum vertical displacement very accurately, while some differences were observed in the response history of vertical displacement. The computational time for a single response history analysis based on the simplified model amounted to a few minutes, which is significantly less demanding compared to hours required for response history analysis in the case of the refined FE model. The simplified model is thus appropriate for the seismic fragility analysis considering the overtopping limit state. It is shown that the fragility curves are significantly affected by the liquid filling level. The risk for liquid overtopping is quite high in the case of a full tank. However, by considering the variation of filling level during the year, the overtopping risk was observed reduced by approximately 30%. Alternatively, the approximate fragility analysis for the liquid overtopping can be performed by utilizing the Eurocode formula for the vertical displacement of liquid. This approach is straightforward, but the formula does not account for the higher mode effects, which may result in overestimated seismic intensity causing overtopping, as discussed in the paper.     

五箱一体化活性污泥工艺循环周期设置研究

五箱一体化活性污泥工艺采取交替运行方式,不需要污泥和混合液回流,良好的循环周期设置对系统至关重要,通过试验研究对不同循环周期设置时的处理效果进行了比较,对主体段进水池状态进行了跟踪试验,结果表明,在水力停留时间和泥龄分别为13 h、18 d的条件下,主体段按120 min设置时能形成良好的厌氧释磷条件,磷的释放率达到0.88 gP/kg MLSS·h,主体段、过渡段和沉淀段分别按120、60和60 min的周期设置时TP、TN的去除率达到90%以上.     

The ‘climatism’ cartel: why climate change deniers oppose market-based mitigation policy

Mainstream policy responses seek to utilize market mechanisms in an effort to minimize costs for major emitters of greenhouse gases. Presumably, this should win over some climate change deniers who align themselves with think tanks promoting free markets and economic growth. Yet, climate change deniers and free-market activists are as staunchly opposed to market-based climate policy as they are to any other form of climate mitigation. In order to understand why climate change deniers reject market-based policy proposals, an archive of free-market environmental newsletters was analyzed for themes of economic opposition. This analysis revealed how climate change deniers rely upon the concept of a regulatory cartel to connect economic opposition to climate policy with attacks on scientific evidence. Because professional scientists do not operate under conventional private-market incentive structures, neoliberal climate change deniers frame scientific knowledge as an attack on economic freedom when utilized to guide policy governing environment–economy relationships.     

Optimisation of rainwater tank design from large roofs: A case study in Melbourne, Australia

Rainwater tanks for larger roof areas need optimisation of tank size, which is often not carried out before installation of these tanks. This paper presents a case study of rainwater tank evaluation and design for large roof areas, located in Melbourne, Australia, based on observed daily rainfall data representing three different climatic regimes (i.e. dry average, and wet years). With the aim of developing a comprehensive Decision Support Tool for the performance analysis and design of rainwater tanks, a simple spreadsheet based daily water balance model is developed using daily rainfall data, contributing roof area, rainfall loss factor, available storage volume, tank overflow and irrigation water demand. In this case study, two (185 m³ and 110 m³) underground rainwater tanks are considered. Using the developed model, effectiveness of each tank under different climatic scenarios are assessed. The analysis shows that both the tanks are quite effective in wet and average years, however less effective in dry years. A payback period analysis of the tanks is preformed which reveals that the total construction cost of the tanks can be recovered within 15-21 years time depending on tank size, climatic conditions and future water price increase rates. For the tanks, a relationship between water price increase rates and payback periods is developed. The study highlights the need for detailed optimisation and financial analysis for large rainwater tanks to maximise the benefits.     

The effects of military tank traffic on prairie: A management model

The effect of various frequencies and seasons of military tank traffic on native mixed-grass prairie was examined in a randomized and replicated field experiment. Vegetation (in 10×10 m plots) was subjected to tank traffic at the following rates: (a) one pass per day of training from May until August; (b) one pass per day in May and June; (c) one pass per day in July and August; (d) one pass every three weeks from May until August; (e) zero (control). Species composition and the amount of bare ground were found to vary significantly with traffic frequency. Plant species alien to North America invaded plots subjected to spring driving. Regression analysis showed spring driving to produce more bare ground than summer driving. The regression models suggested that much higher intensities of training could be conducted without damage if spring driving were avoided. Regression models were also used to estimate the frequency of traffic associated with a significant change in species composition, where species composition was expressed as the ratio ofBouteloua gracilis toStipa spartea, an indicator of disturbance-induced change in prairie vegetation. This relationship predicted the capacity of the vegetation of a training area of any given width to support tank traffic without changing species composition. The predictive ability of the model was tested by comparing predicted traffic capacities with the amount of traffic actually applied to two training areas in 1986. Where traffic capacity was exceeded, the model successfully predicted a significantly higher frequency of bare ground and ratio ofBouteloua gracilis toStipa spartea.     

扑救液化石油气储罐爆炸火灾安全距离的确定

液化石油气储罐爆炸火灾是一类比较难于扑救的特殊火灾，如何根据现场的情况快速评估事故危害，并确定灭火指挥和人员疏散的安全距离，是消防指挥员指挥决策的重要问题，也是难点问题。本文研究了液化石油气储罐发生BLEVE时的热辐射和冲击波计算方法，并导出了安全距离的确定方法。对于消防指挥员快速决策具有十分重要的意义。