Global–local interaction and its impact on cities

This introduction paper to the special issue of Journal of Housing and the Built Environment explores the interrelations among ‘globalization, urban systems, and local development’ by focusing on global-local interactions and their impacts on cities. After tackling the idea that globalization is about the spread of capitalism and capitalist principles throughout the world, the paper introduces the questions that each article intends to answer. The issues addressed by these questions were grouped under four headings: global versus local forces and urban change; urban systems within the global network of cities; globalization and property markets; and governance of globalizing cities.     

Ozonation reduces sludge production and improves denitrification

The effectiveness of partial ozonation of return activated sludge for enhancing denitrification and waste sludge minimization were examined. A pair of nitrifying sequencing batch reactors was operated in either aerobic or alternating anoxic/aerobic conditions, with one control and one ozonated reactor in each set. The amount of solids produced decreased with the ozone dose. Biomass in the anoxic/aerobic reactor was easier to destroy (up to 25% of the initial excess sludge) than in the aerobic (10%) one, generating approximately twice as much soluble COD by cell lysis. Denitrification rate improved up to 60% due to additional carbon released by ozonation. Nitrification rates deteriorated much more in the aerobic than in the alternating reactor, possibly as a result of direct destruction of nitrifying autotrophs as well as competition created by growth of heterotrophs receiving the additional COD. Overall, ozonation provided the expected benefits in denitrification and had less impact on nitrification in the alternating reactors.     

Atmospheric deposition of nitrogen at five subtropical forested sites in South China

Elevated concentrations of reactive nitrogen (N) in precipitation have been reported for many cities in China. Due to increased use of fossil fuels and expansion in agriculture, further increases in deposition of ammonia (NHx) and reactive N oxides (NOy) are predicted. Increased deposition of reactive N is likely to affect N dynamics and N runoff in forest ecosystems. Yet, in China little work has been done to quantify the levels of atmospheric N deposition in such systems. Here, we assess the deposition of inorganic N (ammonium, NH4+ and nitrate, NO3-) for five subtropical forest ecosystems in remote and urban areas of South China. Annual volume-weighted concentrations in bulk precipitation range from 0.18 to 1.55 mg NH4+ -N L(-1) and from 0.12 to 0.74 mg NO3- -N L(-1). These values are large and several times greater than those reported for remote sites of the world. The fluxes of total inorganic N (TIN) in wet-only deposition range from 0.8 to 2.3 g N m(-2) yr(-1), with NH4+ -N contributing 54% to 77%. Both the tree canopy and the ground vegetation layer are important in determining the net N flux reaching the forest floor, but the net effect varies from site to site. At TieShanPing (TSP), close to Chongqing city, and at CaiJiaTang (CJT), near Shaoshan (Hunan province), the canopy represents a net source of N, probably due to dry deposition. At the other three sites (LiuChongGuan (LCG), LeiGongShan (LGS), both in Guizhou province, and LiuXiHe (LXH) in Guangdong), a net loss of reactive N from precipitation water occurs in the canopy, probably due to uptake processes. The total annual atmospheric TIN load is estimated to range from at least 0.8 g N m(-2) yr(-1) to 4.0 g N m(-2) yr(-1), with a considerable contribution from dry deposition. Concentrations and fluxes of inorganic N in tree canopy throughfall are greater than those in North America. Also the contribution of NH4+ -N to TIN fluxes in throughfall (40% to 70%) is greater than in North America. Our sites have N deposition levels and NH4+ -N contributions similar to those found in Northwest and central Europe. The TIN loads at TSP and CJT far exceed 2.5 g N m(-2) yr(-1), which is the N deposition load above which NO3- leaching is expected in temperate and boreal forests.     

斯芬克司住宅，赫依曾，荷兰

5座斯芬克司住宅的每一栋各容纳了14间为了充分利用地段和阳光而组织起来的公寓。建筑的体量在背向水面的方向被斜切，从而使得从湖岸和公寓所能看到的湖景不被阻隔。当人在从楼里往上走时，公寓的数目逐层递减。结果产生了一种斯芬克司式的轮廓，面向太阳的屋顶退台置于这个神话中的怪兽的脊背上。每个建筑体量的雨篷设计是不同的，从而使其独特的头部产生一种韵律感——从连接新开拓地和现有大陆的stichtse桥上看去的一条激动人心的天际线。     

Wind-driven rain as a boundary condition for HAM simulations: Analysis of simplified modelling approaches

While the numerical simulation of moisture transfer inside building components is currently undergoing standardisation, the modelling of the atmospheric boundary conditions has received far less attention.     

Segmentbrücke aus textilbewehrtem Beton: Konstruktion,Fertigung, numerische Berechnung

Segmental Textile Reinrorced Concrete Bridge Design, Manufacturing and Numerical Simulation Concrete provides a brought variety of construction and design possibilities. The low tensile capacity of concrete is taken by reinforcement of steel, short fibres or textile fabrics. Textile reinforced concrete (TRC) is a high performance composite in which technical textiles made of high performance fibers are embedded in a fine‐grained concrete matrix. Because of the corrosion resistance of the textile materials, thick concrete covers as known in ordinary reinforced concrete are no longer needed. Slender new concrete elements extend concrete application to completely new fields and gives architects and engineers more design possibilities. Design, reinforcement concept, production, approval tests, and numerical simulations considering uncertain data are demonstrated for the first bridge made of textile reinforced concrete. It is shown that application of this new, sophisticated composite material is already possible, although more research is needed.     

Failure probability prediction based on condition monitoring data of wind energy systems for spare parts supply

The feasibility of maintenance processes relies on the availability of spare parts. Spare part inventory planning is capital intensive. It is based on demand forecasting, which possesses a high potential in reducing inventories. Even if condition monitoring systems are installed in technical systems, condition monitoring information is barely used to predict the failure probability of units. Therefore, an enhanced forecast model, which integrates SCADA information, has been developed. This leads to more accurate spare part demand forecasts. The approach presented in the paper is based on data mining, the proportional hazards model (PHM) and a binomial distribution. It has been validated with maintenance data of wind energy systems.     

Corrosion of NiTi Wires with Cracked Oxide Layer

Corrosion behavior of superelastic NiTi shape memory alloy wires with cracked TiO₂ surface oxide layers was investigated by electrochemical corrosion tests (Electrochemical Impedance Spectroscopy, Open Circuit Potential, and Potentiodynamic Polarization) on wires bent into U-shapes of various bending radii. Cracks within the oxide on the surface of the bent wires were observed by FIB–SEM and TEM methods. The density and width of the surface oxide cracks dramatically increase with decreasing bending radius. The results of electrochemical experiments consistently show that corrosion properties of NiTi wires with cracked oxide layers (static load keeps the cracks opened) are inferior compared to the corrosion properties of the straight NiTi wires covered by virgin uncracked oxides. Out of the three methods employed, the Electrochemical Impedance Spectroscopy seems to be the most appropriate test for the electrochemical characterization of the cracked oxide layers, since the impedance curves (Nyquist plot) of differently bent NiTi wires can be associated with increasing state of the surface cracking and since the NiTi wires are exposed to similar conditions as the surfaces of NiTi implants in human body. On the other hand, the potentiodynamic polarization test accelerates the corrosion processes and provides clear evidence that the corrosion resistance of bent superelastic NiTi wires degrades with oxide cracking.