Relationship between microstructure and bowing properties of calcite marble claddings

The use of thin (20–40 mm) marble as cladding for building facades has increased substantially during the last few decades. Many of the marble facades perform but some durability problems have occurred, especially with calcite marble, when the cladding starts to bow indicating a decrease in strength. This study considers the influence of the microstructure on the bowing of the calcite marble using adjacent grains analysis. Samples with a granoblastic texture all had six adjacent grains while those with a more complex microstructure had up to 13 adjacent grains. The samples with a granoblastic texture had the greatest degree of bowing, suggesting that the microstructure is a crucial parameter for the durability of marble and that adjacent grains analysis could be a fast and easy method to assess the suitability of marble for cladding purposes.     

伯明翰塞尔夫莱杰百货公司，伯明翰，英国

这个设计中蕴含着我们的理想。我们不仅仅要建造一个最高水平的百货公司，同时希望它能够成为伯明翰的地标，使建筑真正成为城市复兴的催化剂。这个目标激励我们进行设计。     

On the measurement of comparative advantage

This paper shows that the standard measure of revealed comparative advantage (RCA), ranging from 0 to ∞, has problematic properties. Due to its multiplicative specification, it has a moving mean larger than its expected value of 1, while its distribution strongly depends on the number of countries and industries. These properties make its outcomes incomparable across time and place and its economic interpretation problematic. We propose an alternative measure, the additive RCA, ranging from −1 to +1, with a symmetric distribution that centers on a stable mean of zero, independent of the classifications used. Statistical tests show the distribution of the additive index to be more stable. Besides, we propose an aggregate RCA, a regional specialization index, ranging from 0 for pure intra-industry trade to 1 for pure inter-industry trade. The same conclusions and proposals hold for the multiplicative location quotient (LQ), which is used as a measure for the revealed locational attractiveness of certain regions or countries for certain types of industry.

Microscale fluctuation assay coupled with Sep-PakR concentration as a rapid and sensitive method for screening mutagens in drinking water

A sensitive short-term mutagenicity test, the microscale fluctuation test has been coupled with a concentration method based on adsorption on Sep-Pak^R C₁₈ cartridges as a method for screening drinking water mutagens. Comparison with XAD-2 concentration method showed that Sep-Pak adsorbed 5 times higher quantity of organics but was slightly less efficient for adsorbing TOX.Microscale fluctuation test was found to be more sensitive than Ames test by testing known direct-acting mutagens and concentrates of drinking water. Samples derived from conventional treatment including chlorination from eight surface water supplies in Norway were concentrated at pH 2 by adsorption on the disposable columns. The adsorbates were tested at different doses by the microscale fluctuation assay. The mutagenic properties of drinking water samples were also related to total organic carbon (TOC), total organic halogen (TOX) and trihalomethanes (THM) concentrations. Dose-related mutagenic responses were found for all the samples with S. typhimurium TA 100 and TA98 strains without metabolic activation. Good relationship was found between mutagenicity data and TOX and THM results. The method showed to be simple, rapid and suitable for routine screening of mutagens in drinking water.     

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.     

Close-range blast loading on empty recyclable metal beverage cans for use in sacrificial cladding structure

This article deals with the experimental and numerical blast study on a single empty recyclable metal beverage can. The idea is to make a macro-foam (sacrificial cladding structure) out of these cans to protect the main load bearing members of civil engineering structures from the air blast load. Close-range free air blast tests have been conducted to understand the crushing behaviour and the energy absorption of a single empty beverage can in detail. To conduct such an air blast test a special small-scale test set-up was designed and manufactured. The effect of skin plate surface area and its nature on the blast parameters is studied. Furthermore, the effect of inertia of the skin plate on the crushing performance of the beverage can is evaluated. Tests have been conducted with different plates (made of aluminium and sandwich composite materials) with different masses which represent the skin plate of the proposed sacrificial structure. The measured blast parameters from the experimental tests were compared with ConWep predicted data. Furthermore, the influence of the finite surface area of the skin plate on the clearing of the reflected pressure waves was also studied. The deformation behaviour and the corresponding energy absorption of empty beverage cans were captured. During the experimental blast tests it was observed that a part of the total reflected impulse (∼30%) was lost before it transfers to the non-sacrificial structure. Hence, in order to investigate this phenomenon Eulerian-Lagrangian coupled analyses were conducted using Hydrocodes. The results from these analyses showed that the diffraction and ground reflected pressure wave caused the loss in impulse. The results from the numerical studies have been compared and validated with the experimental results.     

MATCHING UNEMPLOYMENT AND VACANCIES IN REGIONAL LABOR MARKETS: AN EMPIRICAL ANALYSIS FOR THE NETHERLANDS

ABSTRACT In this paper we analyze regional developments in unemployment and vacancies in the Netherlands during the 1980s. Our purpose is to establish to what extent the differences in unemployment and vacancy rates are due to difference in regional labor market performance. The analysis is carried out by considering labor market dynamics using the concept of the matching function. We find a constant returns to scale matching function with coefficients of 0.25 for unemployment and 0.75 for vacancies. Efficiency rises substantially during the recession in the beginning of the 1980s. Regional differences in efficiency appear to be small for most regions, suggesting that a reduction in regional unemployment should by stimulating regional labor demand.     

On the validity of the cosine projection in wind-driven rain calculations on buildings

Wind-driven rain (WDR) is one of the most important boundary conditions governing the hygrothermal performance and the durability of building facades. Information concerning the quantity of WDR falling onto building facades is an essential requirement as a boundary condition for Heat–Air–Moisture transfer analyses and for building facade design. The quantity of WDR can be calculated with either semi-empirical methods (such as the WDR relationship) or numerical simulation methods that are based on Computational Fluid Dynamics (CFD). The WDR relationship is most often used. It applies the cosine projection to take into account the effect of varying wind direction on the WDR quantity or intensity. Up to now, the validity of the cosine projection for WDR calculations has not yet been investigated. Its use was suggested in the past and it has been adopted for all semi-empirical WDR calculations since then. Also, in the recently developed numerical simulation methods, it is tempting to apply the cosine projection to reduce the computational expense. In the present paper, the validity of the cosine projection is investigated based on 3D numerical simulations of WDR with CFD. It will be shown that the cosine projection, although generally accepted, is not valid and that it can give rise to significant errors.     

Some aspects of the intraregional spatial distribution of local sector activities

This paper focuses on the spatial distribution of economic activities that serve the demands of households within a region. The level of local sector activities is measured by employment per inhabitant. The basic hypothesis relates to how this proportion varies systematically over space for a wide range of geographies, from high values in a city center to low values in areas adjacent to the city center, and asymptotically approaching the average regional level as the distance from the center increases. This defines a curve that we (under quite general conditions) find to be invariant under changes in the spatial residential pattern and the transportation structure. This suggests that relationships of this kind might be a powerful tool in the prediction of regional development.

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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.