Making Markets: Think Tank Legislation and Private Property in Detroit

The growing literature on shrinking and declining cities portrays the problems of vacancy and abandonment as symptoms of the absence of capital, while the policy transfer literature views declining cities as unlikely sites for the incubation of neoliberal urban policy. This study examines how declining cities have become key sites for tailored market intervention, focusing on the collapse of Detroit's land market. Long-term decline has been exacerbated by legislative changes orchestrated by think tanks seeking to reinvigorate the market for private property while using homeownership for neighborhood stabilization. Analysis of legislative proceedings, tax foreclosure auction data, and interviews with developers, officials, and activists document the trajectory of these policies of market fundamentalism and indicate that the primary “stabilization” has involved a revitalization of the conditions for predatory capital accumulation in a declining city.     

水质对虾池附着性纤毛虫数量变动的影响

研究了中国对虾Ｐｅｎａｅｕｓｃｈｉｎｅｎｓｉｓ育苗池和养成池１１项水质参数（温度、盐度、ｐＨ、溶解氧和化学需氧量、硫化物、硝酸盐、亚硝酸盐、氨氮、磷酸盐及硅酸盐浓度）对虾池附着性纤毛虫的附着速率和对虾体表附着性纤毛虫附着量变动的影响。相关分析结果表明，虾池附着性纤毛虫的附着速率（Ｒ）与虾池化学需氧量（ＣＯＤ）之间存在着直线正相关关系：在育苗池内，Ｒ１＝０．００２＋０．２６０ＣＯＤ（ｒ＝０．７１１，ｐ＜０．０５），在养成池，Ｒ２＝０．５５３＋０．０９８ＣＯＤ（ｒ＝０．６６８，ｐ＜０．０５）。Ｒ与水质其他因子之间未发现有明显的相关关系。对虾体表纤毛虫的附着量（Ｍ）与虾池纤毛虫的附着速率（Ｒ）之间存在着指数正相关关系：在育苗池，Ｍ＝０．５１２ｅ４．０１Ｒ（ｒ＝０．６９２，ｐ＜０．０５）；在养成池，Ｍ＝０．４０９ｅ８．２１Ｒ（ｒ＝０．６７１，ｐ＜０．０５）。说明虾池附着性纤毛虫的附着速率和对虾体表纤毛虫附着量的变动主要取决于虾池ＣＯＤ含量的变化。     

On the development of ship anti-roll tanks

This paper reviews the development of ship anti-roll tanks from the 1880s to the present day including their modelling and control strategies. Mention is also made of other ship roll stabilization systems and the application of the technology to stabilization of other structures. The potential for the use of roll stabilization tanks on modern, high speed multi-hull craft which also have a low speed operational requirement is also discussed.     

A Dynamic Model to Simulate Spills of Fuel and Diesel Oil in the Terrestrial Environment during Extreme Fluvial Floods

Extreme fluvial floods may cause severe contamination with fuel oil and diesel, originating from gasoline pipes and tanks in private households and industrial areas, respectively. Geo‐referenced oil spills in the region of Bitterfeld (Germany) after extreme flood events, such as in August 2002, were simulated using the two‐dimensional (2D) Finite Element model system Telemac2D, which is subdivided into a hydrodynamic (Telemac‐2D) and a transport module (Subief2D). Fuel oil settled via adhesion showed a thickness of less than 1.0 mm. Fuel oil concentrations on the flood wave amounted up to 80 g m^–3 in the vicinity of the point sources. At a distance of several hundred meters downstream of the point sources, the fuel oil concentrations were calculated to be zero. Settled areas were only partially contaminated with fuel oil. While one village experienced severe oil contamination, the town of Bitterfeld was almost unaffected by oil spills. It was demonstrated that the 2D transport model applied is capable of simulating fuel oil spills during extreme high waters in the terrestrial environment. Such simulations of fuel oil spills will feed into a GIS‐based decision support system of flood protection.     

Investigation of seismic behavior of fluid–rectangular tank–soil/foundation systems in frequency domain

Main purpose of this study is to evaluate the dynamic behavior of fluid–rectangular tank–soil/foundation system with a simple and fast seismic analysis procedure. In this procedure, interaction effects are presented by Housner's two mass approximations for fluid and the cone model for soil/foundation system. This approach can determine; displacement at the height of the impulsive mass, the sloshing displacement and base forces for the soil/foundation system conditions including embedment and incompressible soil cases. Models and equations for proposed method were briefly explained for different tank–soil/foundation system combinations. By means of changing soil/foundation conditions, some comparisons are made on base forces and sloshing responses for the cases of embedment and no embedment. The results showed that the displacements and base shear forces generally decreased, with decreasing soil stiffness. However, embedment, wall flexibility, and soil–structure interaction (SSI) did not considerably affect the sloshing displacement.     

Assessing the seismic torsional vulnerability of elevated tanks with RC frame-type staging

Recurrence of torsional failure of elevated water tanks in past earthquakes (including 1952 Kern County and recent 1993 Killari earthquakes) has highlighted the importance of this problem. It is established that these structures may have amplified torsion-induced rotation if their torsional-to-lateral natural period ratio τ is close to 1 and amplified displacement of structural elements due to the coupled lateral-torsional vibration if τ is within the critical range 0.7<τ<1.25. The present study aims to estimate the range of variation of τ for usually constructed reinforced concrete elevated water tanks with frame-type stagings for assessing their torsional vulnerability. Closed-form expressions for torsional and lateral stiffness of tank stagings are derived and verified by standard finite element software. These expressions are used for studying the variation of τ for feasible ranges of influencing parameters. It is seen that a very large number of such tanks may have τ within the said critical range. Closed-form expressions for moments and shear forces of columns and beams under torsion and that under lateral force are also derived. It is also seen with the help of these expressions that the frame stagings of these tanks normally designed for seismic lateral force, may yield through formation of plastic hinges simultaneously in all columns instead of in beams if they are subjected to large rotational response for having τ possibly very close to 1. Such a pattern of yielding generally converts the whole system suddenly into a mechanism causing immediate collapse. Therefore, torsional coupling seems to be a potential cause of failure for these structures.     

Seismic assessment and retrofit of two heritage-listed R/C elevated water storage tanks

A seismic assessment and advanced retrofit study on two heritage-listed reinforced concrete (R/C) elevated water storage tanks is presented in this paper. The two structures were built between the late 1920s and the early 1930s as water suppliers for a coal power plant in Santa Maria Novella Station in Florence, and are still in service. The first, taller tank has a R/C frame supporting structure and is currently used as water supplier for trains and platform services. The second, shorter tank, with a shaft-shell supporting structure, is used as water tower for the Station. The dynamic behaviour of the fluid is simulated by means of a classical convective and impulsive mass model, for which a discrete three-dimensional schematization is originally implemented in the finite element analysis. The time–history assessment enquiry highlights numerical collapse of the frame structure in the taller tank, and unsafe tensile stress states in a large portion of the shaft structure of the shorter one, under seismic action scaled at the maximum considered earthquake level. Based on these results, two retrofit hypotheses are proposed, and namely a dissipative bracing system incorporating pressurized fluid viscous spring-dampers, for the taller tank, and a base isolation system including double curved surface sliders, for the shorter one. The mechanical parameters, design criteria and technical implementation details of the two rehabilitation strategies are illustrated. The verification time–history analyses in protected conditions show that a substantial enhancement of the seismic response capacities of both structures is attained as compared to their original configurations, with little architectural intrusion, quick installation works and competitive costs.     

Dynamic buckling and seismic fragility of anchored steel tanks by the added mass method

Buckling plays a fundamental role in the design of steel tanks because of the small thicknesses of the walls of this class of structures. The first part of the paper presents a review of this phenomenon for liquid‐containing circular cylindrical steel tanks that are fully anchored at the base, considering the different buckling modes and especially the secondary buckling occurring in the top part of the tank. A case study based on a cylindrical tank is then introduced in order to investigate various aspects of dynamic buckling. The finite element model of the case study tank is set‐up using the added mass method for fluid modelling. The influence of pre‐stress states caused by hydrostatic pressure and self‐weight on the natural periods of the structure is first studied and it is found that this influence is very small as far as the global behaviour of the tanks is considered, while it is important for local, shell‐type, vibration modes. In the following, the efficiency and sufficiency of different ground motion intensity measures is analysed by means of cloud analysis with a set of 40 recorded accelerograms. In particular, the peak ground displacement has been found being the most efficient and sufficient intensity measure so far as the maximum relative displacement of the tank walls is concerned. Finally, incremental nonlinear time‐history analyses are performed considering the case study structure under recorded earthquake ground motions in order to identify the critical buckling loads and to derive fragility curves for the buckling limit state. Copyright © 2013 John Wiley & Sons, Ltd.     

Experimental investigation on the seismic response of a steel liquid storage tank equipped with floating roof by shaking table tests

In this paper, the effectiveness of the base isolation on steel storage tanks has been investigated through numerical models and then checked by shaking table tests on a reduced scale (1:14) model of a real steel tank, typically used in petrochemical plants. In the experimental campaign the floating roof has also been taken into account. The tests have been performed on the physical model both in fixed and isolated base configurations; in particular two alternative base isolation systems have been used: high‐damping rubber bearings devices and sliding isolators with elasto‐plastic dampers. Finally, a comparison between experimental and numerical results has also been performed. Copyright © 2009 John Wiley & Sons, Ltd.