T形肋GFRP抗剪连接件的静载推出试验

为改善玻璃纤维增强塑料（GFRP）与混凝土的界面粘结性能,进行了3组共计9个T形肋GFRP抗剪连接件的静载推出试验,主要考虑了T形肋内开孔及横向穿孔钢筋2个参数对其抗剪性能的影响,得到了破坏形态、裂缝分布规律及荷载 相对滑移关系,分析了T形肋对GFRP抗剪连接件粘结滑移性能、极限承载力以及破坏机理的影响。基于试验得到的破坏机理建立了T形肋GFRP抗剪连接件的极限承载力计算公式。结果表明:T形肋增加了GFRP抗剪连接件与混凝土的接触面积,提高了界面的粘结力;界面出现滑移后,T形肋孔内的混凝土榫或钢筋混凝土榫能提供更好的抗剪性能;孔内是否配置横向穿孔钢筋将导致试件出现2种不同的破坏形态。     

Fate and transport of emissions for several trace metals over the United States

A regional model for atmospheric photochemistry and particulate matter is used to predict the fate and transport of five trace metals: lead, manganese, total chromium, nickel, and cadmium over the continental United States during January and July 2001. Predicted concentrations of the metals are compared to observations. Lead predictions have the lowest mean differences with observations and the highest correlation coefficients. They best agree with observations made in January over residential and commercial areas in the eastern United States and worst with observations over remote forests and deserts located in the western United States during July. Manganese predictions show similar abilities to reproduce observations but had larger changes between months. Chromium and nickel predictions show diminishing ability to reproduce observations over both urban and rural areas. Cadmium predictions show the least ability to reproduce observations. Potential causes are examined for the errors in predictions. For errors in lead, manganese and perhaps chromium predictions, aerial suspension and biomass burning are suspected because simulations did not include emissions from these sources. Nickel, cadmium and, to a lower extent, chromium predictions suffer from errors in the emissions that represent current anthropogenic activities. Predicted concentrations of all metals show errors from not including sub-grid processes in meteorological and emission rates. Examples include sea breeze circulation along coastal areas and individual sources in urban areas. These errors reduce the ability to reproduce the time dependence of observations.     

Voting for highway construction in economic geography

This paper investigates the efficiency of voting for provision of transportation infrastructure such as highways, and discusses the effect on regional structure. The salient conclusions of this study show that voting and political competition engender overprovision of large-scale transportation infrastructure. In addition, consideration of industrial location reveals that the provision of transportation infrastructure exerts a negative effect on development of rural areas.     

温度对微生物诱导碳酸钙沉积加固砂土的影响研究

利用尿素水解菌ATCC 11859,在10℃,20℃,30℃的环境下进行了微生物诱导碳酸钙沉积(MICP)水溶液试验、一维砂柱加固试验和细菌活性试验。研究表明,水溶液试验中,温度对于MICP的影响和反应时间有关,反应前期,温度较高的环境下钙离子消耗量较大,反应一段时间后温度较低的环境下钙离子消耗量较大;砂柱试验中,温度较低的环境下加固形成的砂样无侧限抗压强度较大,碳酸钙含量的检测表明,环境温度越高,砂柱中生成的碳酸钙含量越低;无侧限压缩试验的应力应变关系表明,相对低温条件下MICP处理的砂样在达到峰值强度时能够产生较大的变形;不同温度下细菌活性试验表明,细菌活性衰减较快是高温环境下碳酸钙的最终沉积量较小的原因。     

借景:借山景、水景、人文之景——山东泰安泰山庄园住宅小区设计

居住区设计在推敲其中居住空间的时候,其实是在设想其中生活状态。一种生活状态不会凭空产生或消失,这与当地的自然状况、历史传承、人文氛围等因素密切相关。文章结合山东泰安泰山庄园住宅小区规划与建筑设计,从借山景、水景、人文之景等三方面讨论了基于特定地缘文化的居住区设计思路。     

Comparative study of dark patinas on granitic outcrops and buildings

Formation of dark patinas on rocky surfaces is mainly related to the deposition of gases and particles and to sulphation mechanisms. In the present study, samples of dark patinas taken from granitic outcrops and from granitic buildings were examined in an attempt to understand the mechanisms of their formation. The outcrops are located in non-polluted areas and are characterized by the absence of any extraneous material that provides calcium, such as e.g. mortar. The buildings are located in areas with low levels of pollution. The climate in the study area favours proliferation of microorganisms. Important differences between the patinas sampled from outcrops and from buildings were observed, as the former are of biological origin and the latter of anthropogenic origin. Although the levels of pollution are low in the sampling area, sulphur was present in all of the samples from urban buildings. Sulphur was not present in patinas from outcrops or in patinas from monuments that are assumed to behave as outcrops (dolmens), although the latter are also of anthropogenic origin. Finally, the patinas were found to be formed by elements accumulated on the surface and not from elements contained within the rock itself.     

Plant-available lead and other metals in British garden soils

An account is given of an investigation of the fertility status and heavy metal content of garden soils in England and Wales and the availability to and uptake of lead by radish generally, and by potatoes in two villages of contrasting epidemiological history. Intentional interference (i.e., cultivation) of gardens by man has resulted in a generally high level of fertility, but inadvertent additions of lead and other metals have resulted in many garden soils being contaminated. There are regional differences in fertility but not in heavy metal content. In rural areas, uncontaminated soils were associated with allotments and new gardens, and lead contamination was identified in urban and industrial areas as a result of pollution from vehicle exhausts, industry, mining and miscellaneous sources. Mature gardens in rural areas were also contaminated by lead and evidence is presented to support a hypothesis of increasing pollution with time, perhaps due to coal ash from chimneys. Radish absorbed soil lead and certain gardens produced plants the lead content of which was close to or above the legal limit of 2 mg/kg Pb. Potato was a weaker absorber of lead but plant contents still reflected lead contamination of soil. Consumption of vegetables from contaminated gardens could account for an appreciable proportion of the maximum safe daily intake of lead.     

自然保护地及其毗邻区人类活动影响研究： 进展与展望

人类活动超载、土地破坏性利用在自然保护地毗邻区普遍存在,是自然保护地栖息地丧失与生态系统退化的主要因素,对全球生态安全构成严重威胁。中国自然保护地毗邻区人口众多,保护发展“兼用”属性明显,治理成本高,管控难度大。且自然保护地及其毗邻区人类活动影响具有溢出性、复杂性、动态性等特征,对其影响评估、作用机理和管控策略等研究成为众多学者近年来关注的重要议题。为厘清自然保护地及其毗邻区人类活动影响研究进展,采用叙述性文献综述法,从洞势、明律、释理和施策4个方面,系统梳理自然保护地及其毗邻区人类活动影响研究领域的国际进展。研究洞察了自然保护地及其毗邻区人类活动影响研究的价值和趋势;明晰了环境监测实验、数理模型模拟和社会科学研究3种揭示人类活动影响规律的基本研究范式;阐释了人类活动影响的机理、效应和机制3类核心研究议题;揭示了人类活动影响管控的空间和程序2条根本途径,并对其面临的挑战进行了探讨。研究认为自然保护地人类活动影响研究应将关注视野拓展至毗邻区乃至自然保护地网络,加强人与自然相互作用研究和地域性实践,协同空间途径和程序途径,发展动态治理体系。     

REGIONAL PARTNERSHIPS AND METROPOLITAN ECONOMIC DEVELOPMENT

Regional partnerships have grown popular as mechanisms to address public goods that transcend local boundaries, but we know little about their effectiveness. For example, what impact do regional economic development partnerships (REDPs), cooperative organizations of local governments, nonprofits and business organizations have on the economies of metropolitan areas? This article employs survival analysis and multilevel growth curve models to examine how the emergence of regional partnership arrangements influences patterns of economic development in U.S. metropolitan areas. The results suggest that, whereas these organizations do not make a great difference in some metro areas, in densely populated and politically fragmented metropolitan areas personal incomes, business firms, and employment grew significantly with the emergence of REDPs. Furthermore, state level factors, such as intergovernmental grant funding, are found to have positive influences. In conclusion, we discuss regional partnerships as solutions to institutional collective action problems in economic development and other policy arenas.     

Characterising humic acid fouling of nanofiltration membranes using bisphenol A as a molecular indicator

Fouling of nanofiltration (NF) membranes by humic acids was investigated using bisphenol A (BPA) as an indicator chemical to differentiate between various mechanisms that may lead to a change in solute rejection. Three commercially available NF membranes were investigated and an accelerated fouling condition was achieved with a foulant mixture containing humic acids in an electrolyte matrix. The effects of membrane fouling on the rejection of BPA were interpreted with respect to the membrane pore sizes and the fouling characteristics. Results reported here indicate that calcium concentration in the feed solution could be a major factor governing the humic acid fouling process. Moreover, a critical concentration of calcium in the feed solution was observed, at which membrane fouling was most severe. Membrane fouling characteristics were observed by their influence on BPA rejection. Such influence could result in either an increase or decrease in rejection of BPA by the three different membranes depending on the rejection mechanisms involved. It is hypothesized that these mechanisms could occur simultaneously and that the effects of each might not be easily distinguished. However, it was observed that their relative contribution was largely dependent upon membrane pore size. Pore blocking, which resulted in a considerable improvement in rejection, was prominent for the more open pore size TFC-SR2 membrane. In contrast, the cake-enhanced concentration polarisation effect was more severe for the tighter NF-270 and NF-90 membranes. For hydrophobic solutes such as BPA, the formation of the fouling layer could also interfere with the solute-membrane interaction, and therefore, exert considerable influence on the separation process.     

基于地域的景观温室热带雨林展示区 景观设计

通过对原生热带雨林景观特征的研究以及中国3个 以植物原生境为展示特色的植物园景观温室热带雨林展示区的 调查研究,发现景观温室设计上对雨林原生状态景观的表现存 在雨林类型呈现不完全、地域性不足、整体性不明显等问题。 在世界热带雨林各分布区地域特征分析的基础上,提出景观温 室热带雨林展示区以非洲雨林群系、美洲雨林群系以及印度- 马来雨林群系作为主题。从不同地域主题出发,从地形、土 壤、水体、文化、植物等景观要素的设置上进行景观设计,旨 在展现不同雨林群系的地域特色,为景观温室热带雨林展示区 景观设计提供参考。     

Reducing the risks of children living near the site of a former lead smeltery

The sources of lead exposure, soil, household dust, diet and ambient air near a former lead smeltery were studied. The blood lead level of small children was also determined. The aim of the study was to define, based primarily on blood lead measurements, whether children living in the contaminated area may be at risk. Within 500 m from the site of the smeltery, there were several areas where the Finnish limit value for soil Pb, i.e. 300 mg/kg, was exceeded. In the recently built areas, the surface soil has been replaced and soil remediation has taken place in schoolyards and the playgrounds of children's day-care centres. Lead content in household dust was clearly elevated in the contaminated areas. In approximately 20 years, after the smeltery was closed in 1984, the lead concentrations of the fruits and berries in local gardens have decreased to one-tenth. In some samples, the limit values are still exceeded. The lead concentration in ambient air is now 50 times lower than in the 1970s. The blood lead level of the children living in the area is slightly but statistically significantly higher than that of the children in the control areas. The critical blood lead level, i.e. 10 microg/100 ml, was not exceeded in any of the children examined. The average and maximum lead concentrations of 63 analysed blood samples were 2.2 and 5 microg/100 ml, respectively. In contrast, the average and maximum blood lead levels of school children in 1981 were 6.7 and 13.0 microg/100 ml, respectively. The risk reduction measures undertaken during the past 20 years are described.     

Chronic low-level lead exposure: behavioral consequences, biological exposure indices and reversibility

In accord with evidence from human studies, vulnerability of the rat to lead can be shown to extend to exposures initiated beyond the prenatal/neonatal stage of development. Chronic postweaning exposure to lead acetate in drinking water produces characteristic changes in learned behaviour maintained by food reward. These performance effects are related to both exposure concentration and duration. Correlations between biological exposure indices and behavioral changes may be improved by focusing on the maximal behavioral effect and the use of biological indices which reflect cumulative rather than recent exposure. Reversibility of lead-induced changes in behaviour depend upon exposure level; higher exposure level effects linger long after exposure ends despite marked reductions in brain lead.     

Home Sweet Home: the Effect of Sugar Protectionism on Emigration in Italy, 1876-1913

Protectionist policies have often relevant effects at the regional level. This paper analyzes the impact of sugar import duties on emigration in nineteenth century Italy. Both for climatic reasons and the nature of the soil, the cultivation and processing of sugar beets was geographically concentrated. Our theoretical model illustrates how a tariff that favours local producers may affect residents' incentives to migrate abroad. Using a new set historical data, the predictions of the model are tested through quasi-experimental methods which use the exogenous variation in sugar cultivation across areas to estimate the effect of interest. Results show that protectionism reduced the relative incentive to migrate away from sugar-producing areas.     

The effects of trade openness on regional inequality in Mexico

This paper attempts to shed light on the debate about the effect of trade openness on regional inequality, by exploring the specific mechanisms through which this relationship might operate. It does so by testing the hypothesis, based on endogenous growth theory, that a region’s ability to capture the benefits of trade openness depends on key regional characteristics—its critical endowments—and therefore the degree to which trade will reduce regional inequality in a given country is mediated by the geographic distribution of its endowments. I test the hypothesis in Mexico, using statistical analysis of an original sub-national dataset that runs from 1940 to the present. The results indicate that opening up to trade benefits more those regions with lower levels of education, thereby tending to reduce regional inequality. However, opening up to trade also benefits more those regions with higher levels of income and infrastructure, thereby tending to increase regional inequality. This latter effect is greater than the former, so that the overall effect of trade openness is to increase regional inequality.     

No time for crime? The effect of compulsory engagement on youth crime

This paper examines the potential incapacitation effect on various categories of crime committed by young persons. I exploit the increase in compulsory education-work participation age from 15 to 17 in Australia's largest state. The policy primarily increased participation in schools with high enrolments in school-based vocational education programs. By using incidents of crime, I incorporate incapacitation effects on crimes that do not lead to arrests and provide net effect of the policy. Results show substantial reduction in incidents of crime, particularly by male offenders in urban areas and suggest that the policy did not displace crime from streets to schools. Crimes against property, which are often diverted from the criminal justice system, show the largest decline.     

常用无机盐对溶液表面张力及混凝土性能的影响

为研究混凝土中常用的无机盐类外加剂对混凝土性能的影响,采用吊环法测试了不同浓度氯化钠、氯化钙、硫酸钠和硝酸钙水溶液和饱和氢氧化钙溶液的表面张力.试验结果表明:加人无机盐两种溶液的表面张力均增大,且表面张力与溶液的浓度基本呈线性关系.并通过理论分析证明表面张力的增大对混凝土的许多性能有着不利作用,特别是对混凝土的塑性收缩、干缩以及早期开裂有十分不利的作用.     

Regional differences in returns to education for entrepreneurs versus wage earners

Many studies suggest that rates of return to schooling are lower for entrepreneurs than for employees, although the opposite has also been reported. This paper analyses the returns to education for entrepreneurs in urban and rural regions in Finland and compares these to the returns for wage earners. These areas show different rates of self-employment, higher rates being found in rural areas and lower rates in urban areas. The analysis is based on a rich, register-based dataset that includes a 7% random sample of all Finns. To avoid potential sources of bias, Mincer-type income equations are estimated using different estimation procedures. The results show regional variation in returns to education. In rural areas, returns to education are somewhat higher for entrepreneurs than for wage earners. Highly educated entrepreneurs especially gain advantage from their education. In urban areas as well as in the entire country, the returns for the two occupation groups are rather similar.     

Lead contamination of the environment in Russia

Contamination of the environment by lead is recognised throughout the world as one of the major environmental problems. The main goal of this paper is to present objective and systematic data on this problem in Russia. Here we show that in spite of a crisis of industry, the degree of contamination of various parts of the environment in urban areas remains very high. A considerable proportion of the urban population of the country, especially children, are running the risk of a detrimental effect of lead compounds in various parts of the environment and in foodstuffs.     

高钙粉煤灰混合水泥体积稳定性的研究

通过试验研究了高钙粉煤灰混合水泥硬化水泥浆体的体积安定性和自由线膨胀率,探讨了高钙粉煤灰中游离氧化钙对混合水泥体积稳定性的影响规律及作用机理。结果表明,无论是掺加原状高钙粉煤灰还是经机械力化学改性后的高钙粉煤灰,混合水泥的雷氏夹膨胀值均随高钙粉煤灰掺量的增加而增大,不同类别高钙粉煤灰对混合水泥净浆自由线膨胀率的影响规律也与其相似。混合水泥中由高钙粉煤灰引入的游离氧化钙量超过一定限度时,水泥的体积安定性会产生突变,混合养护条件下高钙粉煤灰混合水泥净浆能否补偿收缩取决于由高钙粉煤灰引入的游离氧化钙量。