受内压圆柱筒体开孔-接管区应力集中的有限元分析

利用 ANSYS有限元分析软件通过三个算例对圆柱形筒体小开孔直接管区、大开孔直接管区、大开孔斜接管区的应力分布状况进行了研究 .从中了解到了最大第一主应力的变化规律 ,得出在弹性范围内的应力集中系数 ,并且得到ASME规范中的算式较好的验证     

Sampling Strategies for Toxic Air Contaminants

Annual concentrations of toxic air contaminants are of primary concern from the perspective of chronic human exposure assessment and risk analysis. Despite recent advances in air quality monitoring technology, resource and technical constraints often impose limitations on the availability of a sufficient number of ambient concentration measurements for performing environmental risk analysis. Therefore, sample size limitations, representativeness of data, and uncertainties in the estimated annual mean concentration must be examined before performing quantitative risk analysis. In this paper, we discuss several factors that need to be considered in designing field-sampling programs for toxic air contaminants and in verifying compliance with environmental regulations. Specifically, we examine the behavior of SO2, TSP, and CO data as surrogates for toxic air contaminants and as examples of point source, area source, and line source-dominated pollutants, respectively, from the standpoint of sampling design. We demonstrate the use of bootstrap resampling method and normal theory in estimating the annual mean concentration and its 95% confidence bounds from limited sampling data, and illustrate the application of operating characteristic (OC) curves to determine optimum sample size and other sampling strategies. We also outline a statistical procedure, based on a one-sided t-test, that utilizes the sampled concentration data for evaluating whether a sampling site is compliance with relevant ambient guideline concentrations for toxic air contaminants.     

农药学课程教学改革的探讨

农药学作为专业基础课，其理论与实践教学改革具有重要意义。从培养学生的创新精神与实践能力出发，我们针对教材、教学方法及其实践环节等进行了一系列改革。重点是教材建设、利用多媒体等教学手段，增设综合性和设计性实验、加强实践教学，多种途径调动学生的学习积极性和主动性，提高了教学效果与学生分析和解决实际问题的能力。     

Assessing Risk‐Based Upper Limits of Melamine Migration from Food Containers

Melamine contamination of food has become a major food safety issue because of incidents of infant disease caused by exposure to this chemical. This study was aimed at establishing a safety limit in Taiwan for the degree of melamine migration from food containers. Health risk assessment was performed for three exposure groups (preschool children, individuals who dine out, and elderly residents of nursing homes). Selected values of tolerable daily intake (TDI) for melamine were used to calculate the reference migration concentration limit (RMCL) or reference specific migration limit (RSML) for melamine food containers. The only existing values of these limits for international standards today are 1.2 mg/L (0.2 mg/dm²) in China and 30 mg/L (5 mg/dm²) in the European Union. The factors used in the calculations included the specific surface area of food containers, daily food consumption rate, body weight, TDI, and the percentile of the population protected at a given migration concentration limit (MCL). The results indicate that children are indeed at higher risk of melamine exposure at toxic levels than are other groups and that the 95th percentile of MCL (specific surface area = 5) for children aged 1–6 years should be the RMCL (0.07 mg/dm²) for protecting the sensitive and general population.     

The myth of price convergence under economic integration: A proposed explanation for the difference in food prices across European countries

Conventional globalization theory states that regional economic integration will precede price standardization across participating countries due to the increased buying power of large retail groups and parallel imports. The resulting price corridor should merely reflect differences in logistic costs and short-term, local competitive actions. Yet, this study uses panel data from 25 European countries to examine how hefty food and beverage price differentials between regions remained constant over the last decade. Income, store productivity, and market concentration all contribute to the explanation for regional price differences. These findings suggest that, contrary to straight-line globalization theory, large European retailers’ decisions can influence price convergence and maintain important price dispersion between economically integrated countries. We provide recommendations to enhance market integration.     

Shall we follow the money? Anti-mafia policies and electoral competition

Building upon the evidence that the mafia increases the degree of vote concentration, we use data on regional elections in Sicily to estimate the impact of anti-mafia policies on electoral competition. We find robust evidence that the reassignment for social purposes of property and assets seized to the mafia reduces the degree of electoral concentration. This result supports the hypothesis that policies that create social value, such as the reallocation to social-driven organizations, are more effective than those targeted to public and political institutions.     

Pollutant Ground Concentrations of Nonneutrally Buoyant Particles

A methodology is suggested for the estimation of the mass density and the cumulative ground deposition of a nonvolatile, nonneutrally buoyant, air pollutant (liquid or solid) released from a polluted column (following an explosion caused during routine operation in, e.g., the chemical industry or due to any kind of hostile act) and deposited on the ground via gravitational settling. In many cases, the deposited mass due to gravitational settling constitutes a significant fraction of the original inventory released from the source. Implementation of the methodology in preliminary risk assessments can serve as an efficient tool for emergency planning for both immediate and long‐term measures such as evacuation and decontamination. The methodology considers, inter alia, an estimation of the critical particle diameter, particle size, and mass distributions along the polluted column. This methodology was developed to apply in rural regions since proper application of relevant meteorological input data can be accomplished mainly for such areas.     

Foodborne Exposure to Pesticides and Methylmercury in the United Arab Emirates

As part of a comprehensive environmental health strategic planning project initiated by the government of Abu Dhabi, we assessed potential dietary exposure in the United Arab Emirates (UAE) to methylmercury (in seafood) and pesticides (in fruits and vegetables) above international guideline levels. We present results for the UAE population by age, gender, and body mass index. Our results show very low daily risks of exposure to pesticides in fruits and vegetables at levels exceeding WHO guidelines even under the conservative assumption that no pesticides are removed during washing and food preparation. Thus, exposure to pesticides on fruits and vegetables does not appear to be a major public health concern in the UAE. The chances of exposure to methylmercury in seafood are much higher; our model estimates a mean 1 in 5 daily risk of exceeding the FAO/WHO provisional tolerable weekly intake. However, great caution should be used in interpreting these results, as we analyzed only the risks and not the substantial benefits of fish consumption. In fact, previous studies have demonstrated that exposure to the n‐3 polyunsaturated fatty acids in fish can increase IQ in developing children, and it can substantially decrease the risk in adults of coronary heart disease and stroke. Further research is warranted to compare the risk of Me‐Hg exposure from fish to the nutritional benefits of fish consumption in the UAE and to determine appropriate methods to communicate risk and benefit information to the UAE population.     

Identifying radon-prone building typologies by marginal modelling

Radon is a naturally occurring decay product of uranium known to be the main contributor to natural background radiation exposure. It has been established that the health risk related to radon exposure is lung cancer. In fact, radon is considered to be a major leading cause of lung cancer, second only to smoking. In this paper, we identified building typologies that affect the probability of detecting indoor radon concentration above reference values, using the data collected within two monitoring campaigns recently conducted in Northern Italy. This information is fundamental both in prevention, i.e. when the construction of a new building is planned and in mitigation, i.e. when a high concentration detected inside buildings has to be reduced. A spatial regression approach for binary data was adopted for this goal where some relevant covariates on the soil were retrieved by linking external spatial databases.     

论竞争法上当事人的确定

竞争法案件中,当事人的确定不仅关系到明确权利、义务、责任的承担者,而且是评价市场力量的重要前提,只有在确定了当事人以后,才能进行市场力量的计算,从而评价各种限制竞争行为的后果,判明其违法性。而如何在具体竞争案件中确定当事人,是一个十分复杂的问题。本文针对竞争法的主要领域,即限制竞争协议、支配地位滥用行为以及企业合并情形下当事人的确定规则,进行深入分析,而尤以企业合并情形为重点。在英文中,各种竞争案件的当事人往往称作“undertakingsconcerned”,我们在此将其称作“所涉企业”。