基于减振降噪分析的高效堆垛机设计

物流业的快速发展,使得堆垛机趋向结构大型化和运行高速化。而随之出现的是振动过大及噪声污染问题,既影响产品的动态性能,又存在着安全隐患。为解决上述问题,从堆垛机的结构入手,重点分析振动和噪声产生的主要原因,运用SolidW orks(三维绘图)及其插件Cosmos/W orks(有限元分析)、Cosmos/Motion(动态仿真)软件,通过对不同结构参数和不同结构形式的(超高速/大高度)高效率堆垛机的三维建模、动态仿真与有限元分析,评价其模态和频率指标,摒弃原设计的等截面形式而采用效果最佳的变截面结构形式。结果表明,改进的设计满足设计规范要求,并进一步总结和分析应当重视的问题,对解决高效率堆垛机振动过大和噪音污染问题具有现实的指导意义。     

Single and joint stress of acetochlor and Pb on three agricultural crops in northeast China

In order to evaluate ecological risk of agrochemicals in agricultural environment, single and joint toxic effects of an important herbicide and a typical heavy metal on root elongation of crops were investigated. Seeds of the three crops including wheat （Triticum aestivum）, Chinese cabbage （Brassica pekimensis） and soybean （Glycine max） as the main crops in northeast China were exposed to acetochior as a herbicide and lead （Pb） as a heavy metal using the pot-culture method, and meadow brown soil as one of the main soils distributed in northeast China was applied in the investigation. The results indicated that the interactive effects of the two pollutants on root elongation of the three crops were very complicated although they had markedly significant （P〈0.01） linear interrelationships based on the regression analyses. When the concentration of added Pb^2＋ reached 200 mg/kg, acetochlor and Pb had an antagonistic effect on the inhibition of root elongation of the three crops. However, acetochlor and Pb had significantly （P〈0.05） synergic effects on the inhibition of root elongation when concentration of added Pb^2＋ was up to 1000 mg/kg. At the low concentration of added Pb, joint toxicity of acetochlor and Pb was more dependent on the concentration of Pb. Among the three crops, wheat was the most sensitive to the toxicity of Pb and Chinese cabbage was the most sensitive to the toxicity of acetochlor.     

An overview to CERSSO's self evaluation of the cost-benefit on the investment in occupational safety and health in the textile factories: "a step by step methodology"

INTRODUCTION: The Pan American Health Organization (PAHO) and CERSSO collaborated to develop a new Tool Kit (TK), which became available in May 2002. PAHO already had a TK in place, and CERSSO requested that one be developed for their needs. CERSSO wanted to enable managers and line workers in garment factories to self-diagnose plant and workstation hazards and to estimate the costs and benefits of investing in occupational safety and health (OSH) as a way to improve productivity and competitiveness. METHODS: For consistency, the collaborating organizations agreed to construct the TK according to PAHO's methodology. The instrument was developed to be comprehensive enough that any user can collect the data easily. It integrates epidemiologic, risk assessment, clinic, engineering, and accountability issues, organized to include step-by-step training in: (a) performing risk assessments in the workplaces (risk factors); (b) making cause-effect relationships; (c) improving decision making on OSH interventions; (d) doing calculations of direct and indirect costs and savings; and (e) doing calculation of the overall cost-benefit of OSH interventions. RESULTS AND CONCLUSIONS: Since July 2002, about 2,400 employees and officials from 736 garment factories, Ministries of Labor, Health, Social Security Institutes, and Technical Training Institutions of Central America and the Dominican Republic have used this instrument. Systematically, they have calculated a positive relationship of the investment (3 to 33 times). Employers are now aware of the financial rewards of investing in OSH. The TK is available in Spanish, Korean, and English. In July 2003, a software program in Spanish and English was developed (180 persons have been trained in the region), which requires less time to execute with better reliability.     

清洁生产审计方案评估技术方法探讨

清洁生产审计方案评估是对已获得的清洁生产方案作出科学的，系统的和全面的评估，文章对清洁生产审计方案评估技术方法进行了探讨，提出了清洁生产审计方案评估技术方法包括方案分类评价，方案筛选和可行性分析等内容。     

桂林酸雨中不可溶成份的电镜分析

对广西省桂林市１９８８－０３－１６－１９８８－０３－２９出现的四次系统酸性降水，进行了降水的连续联样和过滤，用电子显微镜观测降水中的不可溶成分，共得到了１２种元素，即Ａｒ，Ｍｇ，Ａｌ，Ｓｉ，Ｐ，Ｓ，Ｃｌ，Ｋ，Ｃａ，Ｆｅ，Ｎｉ和Ｃｒ。用平均值法和聚类法，分析了桂林酸雨中１２种不可溶元素的重量谱特征，以及它们与降水系统之间的关系。     

Characterization of River Networks: A GIS Approach and Its Applications

Fluvial geomorphology provides the basis for characterizing complex river networks and evaluating biophysical processes within watersheds. Understanding the spatial organization of morphological features, their influencing processes, and resultant geomorphic diversity in stream networks are important for efficient restoration, river health assessment, and improving our knowledge of the resilience of riverine landscapes. River characterization is a means to determine the biophysical character of river networks but many methods are fraught with pitfalls, such as the use of incorrect variables and limited acknowledgment of the hierarchical organization of rivers. In this paper, a top‐down geographic information system‐based approach for determining the physical typology of river networks is outlined. A suite of multivariate analyses are used to develop a nomenclature for functional process zones (FPZs) — large tracts of the river network with similar hydro‐geomorphological character. Applied to the Little Miami River, Ohio, six distinct FPZs emerged, which had a nonuniform distribution along the river network. Some FPZs repeated downstream; others were rare in terms of total length and number of FPZ segments. The physical structure of the Little Miami River network was analyzed using a series of community metrics. Application of this approach for river monitoring, establishing reference conditions, as well as management of threatened and endangered species and asset trading is highlighted.     

高速铁路列车运行冲突管理总论

为提高铁路行车指挥水平、保障行车安全,研究了高速铁路列车运行冲突管理问题。以高速铁路运输系统特点分析为基础,在定义高速铁路列车运行冲突后,对列车运行冲突从4个不同角度进行分类。分析列车运行冲突的特点,阐述高速铁路列车运行冲突管理的内涵。列车运行冲突的形成机理研究、冲突分析、冲突消解和基于冲突管理的列车运行调整方法和运行图研究等问题构成中国高速铁路冲突管理的主要研究框架体系。高速铁路冲突管理理论体系的研究是高速铁路运输组织优化的关键问题之一,是高速铁路行车安全的重要保障。     

非膜技术处理生物稳定渗滤液的效果及成本

以经厌氧-好氧处理的生物稳定渗滤液为研究对象,分别比较了其经活性炭吸附、混凝、芬顿和电解处理后的溶解性有机碳(DOC)、COD、溶解性氮(DN)和比紫外吸光度(SUV254)的变化,及去除单位COD的成本变化.研究发现,活性炭吸附、芬顿和混凝对生物稳定渗滤液的COD、DOC和DN的去除效率均随药剂投加量的增加而提高;包...     

Fish consumption reduces transfer of BDE47 from dam to murine offspring

Fish and seafood are important contributions to a healthy diet, but also contain persistent organic pollutants (POPs) like polybrominated diphenylethers (PBDEs) and polychlorinated biphenyls (PCBs). Discrepancies have been found between intake and accumulated levels of POPs, where fish consumers have had similar levels of POPs to the general population. Similarly fish oil consumption has been found to reduce accumulation of POPs. This study examined the accumulation of BDE47 or PCB153 in mice fed diets with different nutritional composition, using female mice with pre-weanling pups exposed through gestation and lactation. A fish-based diet was compared to a standard casein-based rodent diet. All diets had low background levels of environmental contaminants and were spiked with BDE47 or PCB153 to levels representing a realistic (∼0.004 μmol kgbw⁻¹ d) or a high dietary exposure (∼1.3 μmol kgbw⁻¹ d). Accumulation of BDE47 or PCB153 in offspring tissues after 18 d lactation reflected the maternal exposure levels. However, the pups of dams fed a fish-based diet had consistently lower BDE47 accumulation in liver, fat and stomach than pups from casein-fed dams. Similarly the pups of dams fed a high dose of PCB153 in a fish diet also accumulated less PCB153 than pups of the dams fed a casein diet, although not significant. In conclusion, the fish based diets seemed to reduce transfer of BDE47 and PCB153 from dams to pups. The study highlights that in-depth knowledge about nutritional impact on toxicokinetics is of great interest to vulnerable consumers.     

Spatial Patterns of Macrobenthic Communities in Shallow-Water Tidal Embayments and Their Association with Environmental Factors

This study examines the distribution, composition, and structure of benthic communities in nine shallow-water semienclosed embayments on Cape Cod, southeastern Massachusetts. The spatial patterns were used to associate benthic characteristics with local environmental factors. Field data from multiple years were collected to measure macrofaunal abundance, community composition, and environmental characteristics. Multivariate statistics were used to analyze the spatial variations of species composition and the abundance of benthic macrofauna. Canonical ordination, specifically redundancy analysis, was used to determine the relative importance of the environmental factors (nutrients and habitat factors) being studied. The analyses demonstrate that the benthic communities in the shallow tidal embayments are clearly clustered in association with the local environments. Species composition and community structure of the benthic macrofauna are significantly correlated with water column parameters, especially with phytoplankton biomass, total nitrogen, and dissolved oxygen.