A Heart Rate Evaluation Approach to Determine Cost-Effectiveness an Ergonomics Intervention

This paper describes a hear-rate methodology to determine the cost-effectiveness of an ergonomics intervention to reduce workload and improve working conditions. This is a practical approach as opposed to the energy expenditure technique that is difficult to implement in natural settings. This was a laboratory study using a large excavator cabin with devices to simulate excavation operations. Mean heart rate was used to calculate the required rest time during a shift with or without air-conditioning. The criterion for evaluation was differences in required rest time during a shift under these 2 conditions. The simplicity and objectivity of this approach invites use to solve the problem of the economic evaluation of ergonomics interventions.     

Towards Sustainable Integrated Watershed Ecosystem Management: A Case Study in Dingxi on the Loess Plateau, China

The Chinese government initiated a massive conservation program called “Grain-for-Green” in 1999 to reduce soil erosion and improve ecosystem function. Implementing practical sustainable development in the loess plateau still remains problematic, particularly in its eco-fragile areas. Here we discussed an approach for sustainable development at the watershed scale by integrating land use suitability, ecosystem services and public participation in the loess hilly area. We linked land use scenario analysis and economic modeling to compare the outcomes of three scenarios, CLU (Current Land Use), GOLU (Grain-production Oriented Land Use) and PSLU (Potential Sustainable Land Use). The results indicated that compared to PSLU, GOLU may provide a higher economic productivity in the short-term, but not in the long-term. CLU ranked lowest in terms of economic benefits and did not meet the daily needs of the local farmers. To reconcile the land use adjustments with farmers’ basic needs, a labor-saving land use strategy is necessary. Since the PSLU scenario assumes that slope cropland should be converted to pastures or orchards, more time may be available for off-farm work and for more public participation in integrated ecosystem management. Financial support to the local farmers for environmental conservation should be modulated in function of their positive contribution to ecosystem management.     

Support of sustainable management of nitrogen contamination due to septic systems using numerical modeling methods

Nitrogen contamination is a serious concern to sustainable environmental management, and one important source of nitrogen contaminant is due to wastewater treatment using onsite sewage treatment and disposal systems (OSTDS, a.k.a., septic systems). This paper presents a study in which numerical modeling is used to support sustainable decision-making and management of nitrogen contamination by utilizing a recently developed GIS-based software, VZMOD, a Vadose Zone MODel for simulating nitrogen transformation and transport in vadose zone between drainfield of septic systems and water table. VZMOD is based on a physical model of unsaturated flow and nitrogen transformation and transport, and the model is solved numerically using the finite element methods. This is the major difference between VZMOD and other GIS-based software of nitrogen modeling. Using GIS techniques, VZMOD considers spatial variability of a number of hydrogeologic parameters such as hydraulic conductivity and porosity. A unique feature of VZMOD is that VZMOD addresses spatial variability of water table by using VZMOD together with ArcNLET, an ArcGIS-based software developed to simulate groundwater flow and nitrate load from septic systems to surface water bodies. VZMOD is designed to execute in different modes to be compatible with different levels of data availability in various management projects of nitrogen contamination. This paper presents an application of VZMOD at a neighborhood with hundreds of septic systems and heterogeneous hydraulic conductivity, porosity, and water table depth. The modeling results indicate that using septic systems at the considered neighborhood is unsustainable and more management means are necessary.     

可进行择优决策的灰色预测GM（1,1）动态模型

本文提出了一个可进行择优决策的GM(1、1)优化模型。这个模型使原序列的内含信息得到充分开发利用,较好地解决了大样本序列用GM(1、1)建模的问题。实例证明:通过择优指数C_i择取的、以a、u参数外延得到的优化模型,抓住了原序列的主要变化规律,是一个平稳的、具有一定预测能力的模型。     

Petroleum residues in the waters of the Shatt al-Arab River and the northwest region of the Arabian Gulf

During April 1980, water samples were collected from 12 sites in the Shatt al-Arab River and its estuary in the northwest region of the Arabian Gulf. The samples were extracted and the concentration of petroleum hydrocarbons were determined spectrofluorometrically, in order to provide information on the background values of oil generally present in these waters. Total hydrocarbon concentrations of these samples ranged from 2.7 to 86.7 μgL^?1 expressed in terms of Kuwait crude oil equivalents. The highest concentrations were found at sites in the Shatt al-Arab River that are near port areas.     

Soil pollution by petroleum products, III. Kerosene stability in soil columns as affected by volatilization

The stability of kerosene in soils as affected by volatization was determined in a laboratory column experiment by following the losses in the total concentration and the change in composition of the residuals in a dune sand, a loamy sand, and a silty loam soil during a 50-day period. Seven major compounds ranging between C₉ and C₁₅ were selected from a large variety of hydrocarbons forming kerosene and their presence in the remaining petroleum product was determined. The change in composition of kerosene during the experimental period was determined by gas chromatography and related to the seven major compounds selected. The experimental conditions — air-dairy soil and no subsequent addition of water—excluded both biodegradative and leaching. losses.The losses of kerosene in air-dried soil columns during the 50-day experimental period and the changes in the composition of the remaining residues due to volatilization are reported. The volatilization of all the components determined was greater from the dune sand and loamy sand soils than from the silty loam soil. It was assumed that the reason for this behavior was that the dune sand and the loamy sand soils contain a greater proportion of large pores (>4.5 μm) than the silty loam soil, even though the total porosity of the loamy sand and the silty loam is similar. In all the soils in the experiment, the components with a high carbon number formed the main fraction of the kerosene residues after 50 days of incubation.