煤矿安全生产中人的行为影响因子系统动力学(SD)仿真分析

在构建影响人的安全行为因素因果关系的基础上,运用系统动力学(SD)理论和方法,对影响人的安全行为关键因素进行动态预测,并通过仿真计算、对比分析安全投入增加对系统安全水平的影响。应用该方法建立的煤矿生产中人的安全行为指标水平模型,以求证安全投入与人的安全行为水平的相关性,为煤矿安全管理决策提供一种新的思路,亦有助于政府和煤矿企业科学地明确安全投入方向,降低人因事故率,提高煤矿生产的安全水平。     

关于“四沿”化工安全的战略性思考与探索

以基本能浓缩中国化工概貌的江苏省沿江、沿河、沿湖、沿海化工企业为背景,依据其形成和发展及基本概况,结合重大化工事故灾难,以安全与环境相耦合,对"四沿"化工安全进行了战略性思考,试图勾画临水化工本质安全的模型,提出在"四沿"地区构建化工本质安全化科技支撑体系的宏观构架,即建设"江苏省四沿区域化工本质安全和化工事故防范及应急系统"的思路、探索与实践。还提出了立法深化研究和技术标准制定、严格区域规划设计与建设的监督、强化监管执法力度等急需关注的问题。以江苏省"四沿"区域的化工安全为背景所提出的思路与对策,应该对整个华东地区乃至全国临水性化工企业安全具有重要的现实和借鉴意义,对我国高危行业的安全生产和环境保护有重大的示范效应。     

基于灰预测模型的大跨度预应力混凝土桥梁施工监测

运用灰色系统理论,建立大跨度预应力砼刚构-连续组合梁桥悬臂浇筑施工梁段立模标高预测的GM(1,1)模型,并用残差的GM(1,1)模型对其进行修正;同时把该预测模型应用于松原龙华松花江特大桥实际工程;其结果表明梁段立模标高预测精度较高,完全能够满足工程的需要,为同类桥梁的施工监测提供参考。     

Tracking the prevalence of rollover protective structures on U.S. farm tractors: 1993, 2001, and 2004

Problem

Between 1992 and 2005, 1412 workers on farms died from tractor overturns. A Rollover Protective Structure (ROPS) is a proven intervention to reduce overturn deaths. However, farm characteristics that are associated with the adoption of ROPS are not well understood.

Methods

ROPS prevalence statistics were derived from National Institute for Occupational Safety and Health (NIOSH) surveys that tracked ROPS use on farms. Data were from the years 1993, 2001, and 2004.

Results

In 1993, 38% of tractors were equipped with ROPS. This increased to 51% by 2004. ROPS prevalence rates were higher on farms in the Southern region of the United States, on farms where the operator was 25-34 years old, and on farms with $100,000 or more of farm sales. Low ROPS prevalence rates were associated with farm operators 65 years old or older and with farms with less than $10,000 of farm product sales.

Summary

The increase in ROPS prevalence between 1993 and 2004 has not been sufficient to decrease the rate of tractor overturn deaths on farms. Incentive programs targeting older farm operators and low-income farm operations are suggested to increase ROPS use on tractors.

Impact on Industry

The study provides farm characteristics associated with low ROPS prevalence rates. The results can be used to target farms for future ROPS promotion activities.     

Processing and Properties of Mixtures of PHB-V with Post-consumer LDPE

Mixtures of poly-β-(hydroxybutyrate-co-valerate) PHB-V with virgin and post-consumer low density polyethylene (LDPE) were prepared by melt mixing in proportions of 100/0, 90/10, 80/20, 70/30 and 0/100 (wt/wt%). The mixtures were analysed by infrared spectroscopy, differential scanning calorimetry (DSC), dynamic mechanical thermal analysis (DMTA), melting flow index (MFI), tensile tests, scanning electron microscopy (SEM) and biodegradation in simulated soil. The DMTA and DSC curves of post-consumer LDPE suggested that this polymer was a mixture of LDPE and linear low density polyethylene (LLDPE). Virgin and post-consumer LDPE had lower MFI than PHB-V, but the blends showed higher index as the content of LDPE increased. The addition of LDPE reduced the tensile strength and Young’s modulus of the mixtures compared with PHB-V. SEM indicated poor interfacial adhesion between PHB-V and LDPE. PHB-V degraded slow and gradually, while both LDPE showed virtually no degradation under the conditions studied. The biodegradability of the blends depended on their composition and of the type of LDPE. LDPE improved the biodegradability of the mixtures.     

Influence of Technological Process on Biodegradation of PVA/Waxy Starch Blends in an Aerobic and Anaerobic Environment

Improving biodegradability of PVA/starch blends is a reality already documented by a number of works. Admittedly, mechanical properties of products (for example, tensile strength) are somewhat worse, but suitable composition optimizing or chemical modifying of starch may eliminate the problem to a large degree. This work is an attempt to find another potential effect influencing biodegradability, that of technological procedure for producing films from these blends on an extruder. The procedure with a so-called pre-extrusion step (two-stage) and dry-blend (single-stage) produced blends of slightest differences in achieved biodegradability (virtually within limits of experimental error) in aerobic (76 vs. 79%) as well as anaerobic breakdown (48 vs. 52%). Conversely, morphological analysis exhibited superior homogeneity of films prepared by the two-stage process; their tensile strength was also higher.     

Mechanical Property Characterization of Plasticized Sugar Beet Pulp and Poly(Lactic Acid) Green Composites Using Acoustic Emission and Confocal Microscopy

Sorbitol and glycerol were used to plasticize sugar beet pulp-poly(lactic acid) green composites. The plasticizer was incorporated into sugar beet pulp (SBP) at 0%, 10%, 20%, 30% and 40% w/w at low temperature and shear and then compounded with poly(lactic acid) (PLA) using twin-screw extrusion and injection molding. The SBP:PLA ratio was maintained at 30:70. As expected, tensile strength decreased by 25% and the elongation increased. Acoustic emission (AE) showed correlated debonding and fracture mechanisms for up to 20% w/w plasticizer and uncorrelated debonding and fracture for 30–40% sorbitol and 30% glycerol content in SBP–PLA composites. All samples had a well dispersed SBP phase with some aggregation in the PLA matrix. However, at 40% glycerol plasticized SBP–PLA composites exhibited unique AE behavior and confocal microscopy revealed the plasticized SBP and PLA formed a co-continuous two phase system.

Identification of Odor Causing Compounds in a Commercial Dairy Farm

The odorous air emissions from confined animal feeding operations (CAFOs), such as swine, poultry and dairy farms, are increasingly raising community complaints. Odorous emissions can result in health damages, psychological discomforts and adverse aesthetic effects in the community. However, these emissions are not well characterized up to now due to the lack of legislation, the limitations in sampling and instrumentation techniques, and the complexity of the emissions themselves. This study is aimed at the development of a high volume sampler and sorbent assembly to identify the odor causing compounds from a diary CAFO. The sorbent was custom designed to target the potential compounds that may exist in a dairy farm and was validated in laboratory with a synthetic odor from the swine manure. The actual samples at the diary farm were collected in spring and summer of 2005. The sorbents were solvent extracted and individual odor compounds were identified using GC–MS (gas chromatography–mass spectroscopy). The data obtained indicated that high volume sampling can shorten the sampling time from days to within 4 h. Both volatile organic compounds (VOCs) and volatile fatty acids (VFAs) have been identified from the dairy farm, such as phenol, methylphenol, 4-ethyl phenol, indole, methyl indole, benzyl alcohol, hexanoic acid, valeric acid and iso-valeric acid, together with some nitrogen containing compounds that have not been reported before.     

An Assessment of the Ecological Condition of Long Island Sound, 1990–1993

Data from the Environmental Protection Agency's (EPA) Environmental Monitoring and Assessment Program (EMAP) from 1990 to 1993 were used to assess the condition of the Long Island Sound (LIS) estuary. Ambient water, sediment and biota were collected during the summer months from 53 LIS stations using an unbiased sampling design. The design consists of two LIS subunits, LIS proper, and small estuaries (<2.6 km2) at the margins of the Sound. Selected indicators of condition included: benthic species composition, abundance and biomass; fish species composition and gross external pathology; sediment physical and chemical characterization and sediment toxicity; and water clarity and quality. Results of the four-year sampling indicated that 28(±11)% of the areal extent of LIS proper had a benthic index < zero (impacted) and 51(±12)% of the area of small estuaries was impacted. Analysis of the results of other indicators also shows that small estuaries were particularly affected. For example, 42(±10)% of the areal extent of small estuaries exhibited sediment toxicity, and significant chemical contamination was evident in 22% of the area of small estuaries. Low dissolved oxygen (D.O.) concentrations (<5 ppm), however, appeared to affect only the deeper open waters of western LIS. Approximately 48(±12)% of the areal extent of LIS proper documented exposure to at least moderate D.O. stress (<5 ppm). The overall results of this monitoring study indicate that significant anthropogenic impacts have occurred in LIS and that if remediation was to take place, specific localized sediment problems would need attention. Point source and non-point source nutrient inputs to the Sound, which are believed to be the primary causative factor for the observed hypoxic conditions, would also need attention.     

Combining mapped and statistical data in forest ecological inventory and monitoring – supplementing an existing system

A forest ecological inventory and monitoring system combining information derived from maps and samples is proposed based on ecosystem regions (Bailey, 1994). The system extends the design of the USDA Forest Service Region 6 Inventory and Monitoring System (R6IMS) in the Pacific Northwest of the United States. The key uses of the information are briefly discussed and expected results are illustrated with examples. The system is flexible, allowing regions based on ecological considerations to be modified. Sampling intensities that are affordable are likely to be insufficient to provide meaningful estimates for key parameters relating to rare and endangered species, watersheds, and other ecological units. Methods are proposed for collecting additional information in follow-up surveys and combining it with relevant information obtained in R6IMS. Near-continuous information on weather and possible pollution variables recorded by instruments at sampling sites is needed to develop meaningful models to understand what is happening in the ecoregions. R6IMS and the proposed additions constitute a dynamic system which will be modified further as data are analyzed.