Energy from gasification of solid wastes

Gasification technology is by no means new: in the 1850s, most of the city of London was illuminated by "town gas" produced from the gasification of coal. Nowadays, gasification is the main technology for biomass conversion to energy and an attractive alternative for the thermal treatment of solid waste. The number of different uses of gas shows the flexibility of gasification and therefore allows it to be integrated with several industrial processes, as well as power generation systems. The use of a waste-biomass energy production system in a rural community is very interesting too. This paper describes the current state of gasification technology, energy recovery systems, pre-treatments and prospective in syngas use with particular attention to the different process cycles and environmental impacts of solid wastes gasification.     

Mechanical Properties and Lipase-Catalyzed Biodegradation of α-Methyl, ε-Caprolactone/ ε-Caprolactone Copolymers Obtained by Chemical Modification of Poly(ε-caprolactone)

Novel (-caprolactone)-based copolymers of different compositions were synthesized by allowing methyl iodide to react with the polycarbanion that resulted from the action of lithium diisopropylamide on poly(-caprolactone) in THF at –70°C under argon atmosphere. The copolymers were characterized by various techniques, namely ¹H nuclear magnetic resonance, size exclusion chromatography, differential scanning calorimetry, x-ray diffraction and viscoelasticimetry. They were submitted to hydrolytic and lipase-catalyzed enzymatic degradation in comparison with genuine PCL. The Young modulus depended on the degree of methylation. In contrast, loss angle and glass transition temperature did not depend on this parameter. It is shown that the lipase-catalyzed degradation of methylated PCL is much slower than in the case of genuine PCL.     

Seasonal variations of heavy metals in central Greenland snow deposited from 1991 to 1995

To better assess the seasonality in the fallout of heavy metals to central Greenland, a continuous series of 68 snow samples has been collected at a remote site in the Summit area from a 2.7 m pit using ultraclean sampling procedures. This covers a continuous four year time period from spring 1991 to spring 1995. Co, Cu, Zn, Mo, Rh, Pd, Ag, Cd, Sb, Pt, Pb, Bi and U were determined using ultrasensitive inductively coupled plasma sector field mass spectrometry under clean room conditions. In addition we also determined Al by graphite furnace atomic absorption spectrometry and Na+, Ca2+, SO4(2-), MSA and oxalate by ion chromatography, species that will assist in the interpretation of the trace metal data. The data show pronounced inter- and intra-annual variations, with large differences in the amplitude of these variations for the element studied, with few clear seasonality patterns. Generally, high concentrations are observed in the spring snow layers, while much lower concentrations are typical of summer snow layers. Significant correlations are observed between Co, Cu, Zn, Ag and Sb, while Pt, Pd and Rh show no correlation with the other metals. Crustal enrichment factors show that while the crustal dust contribution is probably important for some metals for part of the year (spring), anthropogenic inputs are as important in many instances. Pronounced intra-annual variations are observed for some metals, in particular Pt. The variations observed for this metal parallel fairly closely changes in Russian Pt production, which points to emissions from smelters in the Russian Arctic as likely sources for Pt.     

Influence of climatic conditions and soil type on 99TcO4- uptake by rye grass

Climatic changes over the long term will modify significantly the biosphere, with glaciation events probably taking place in the next 100 000 years. This is important to safety assessments of nuclear waste disposal facilities that contain high-level and long-lived waste.The soils will evolve toward new situations, and their properties will be consequently modified (e.g. an increase of soil organic matter may be expected in a cooler climate). These changes in soil properties would affect the mobility and the soil-to-plant transfer of radionuclides such as (99)Tc. This study aimed at simulating the cooling of climatic conditions for soils representative of a Jurassic limestone plateau, and the effect on transfer parameters of (99)TcO(4)(-) in the soil-plant systems was investigated. The cooler conditions were simulated by increasing elevation, a surrogate for climate change. Soils were sampled in similar geological background and topography at different elevations in the north east of France (Lorraine and Jura). Soil/solution distribution coefficients (K(d)) of (99)TcO(4)(-) were measured on soil samples in short-term batch experiments with 1:10 soil:solution ratio. Rye grass was grown on the soils spiked with (99)TcO(4)(-) at temperature regimes adapted to each soil. Also, two different temperature regimes (cold and temperate) were applied to one soil to test the effect of plant physiology and evapotranspiration on (99)TcO(4)(-) uptake. K(d) values did not show significant differences among soils in aerobic conditions, and were not significantly different from 0. During plant culture, reduction of (99)Tc was never totally achieved in soils, including in a peaty OM soil. Concentration ratios (CR) were calculated on a dry weight basis and ranged from 20 to 370. CR were always higher in high temperature regimes than in cold temperatures. They were also inversely correlated with soil organic matter (OM) content. A decrease of CR values from 5 to 10-fold was observed with increasing soil OM. Results suggested that the water holding capacity, in which (99)Tc is diluted, the nitrification potential of the soils and the evapotranspiration of plants (efficiency of uptake of soluble (99)TcO(4)(-)) were strongly involved in these differences.     

On-road driving evaluations: a potential tool for helping older adults drive safely longer

PROBLEM: This paper explores the potential use of on-road driving evaluations as a tool for helping older adults extend their safe driving years. METHOD: Three separate research activities were carried out. The first was a national telephone survey of current and former older drivers. The results of this survey provide information relevant to the potential market for on-road driving evaluations. The second was a series of focus groups with potential stakeholders in the process: driver educators, occupational therapists, and physicians. These groups explored the feasibility and requirements of offering on-road driving evaluations to the wider public. Supplemental data were also collected from a mail survey of driving schools nationwide. RESULTS: Based on the results of these efforts, a number of recommendations are presented for expanding the availability of on-road driving evaluations, specifically to help older adults make more responsible decisions about continuing or stopping driving, and more generally to help them drive safely longer.     

Modelling of silica diffusion experiments with 32Si in Boom Clay

A mathematical model describing the dissolution of nuclear glass directly disposed in clay combines a first-order dissolution rate law with the diffusion of dissolved silica in clay. According to this model, the main parameters describing the long-term dissolution of the glass are etaR, the product of the diffusion accessible porosity eta and the retardation factor R, and the apparent diffusion coefficient D(app) of dissolved silica in clay. For determining the migration parameters needed for long-term predictions, four Through-Diffusion (T-D) experiments and one percolation test have been performed on undisturbed clay cores. In the Through-Diffusion experiments, the concentration decrease after injection of 32Si (radioactive labelled silica) was measured in the inlet compartment. At the end of the T-D experiments, the clay cores were cut in thin slices and the activity of labelled silica in each slice was determined. The measured activity profiles for these four clay cores are well reproducible. Since no labelled silica could be detected in the outlet compartments, the Through-Diffusion experiments are fitted by two In-Diffusion models: one model assuming linear and reversible sorption equilibrium and a second model taking into account sorption kinetics. Although the kinetic model provides better fits, due to the sufficiently long duration of the experiments, both models give approximately similar values for the fit parameters. The single percolation test leads to an apparent diffusion coefficient value about two to three times lower than those of the Through-Diffusion tests. Therefore, dissolved silica appears to be strongly retarded in Boom Clay. A retardation factor R between 100 and 300 was determined. The corresponding in situ distribution coefficient K(d) is in the range 25-75 cm(3) g(-1). The apparent diffusion coefficient of dissolved silica in Boom Clay is estimated between 2 x 10(-13) and 7 x 10(-13) m(2) s(-1). The pore diffusion coefficient is in the range from 6 x 10(-11) to 1 x 10(-10) m(2) s(-1).     

Investigating the Surface Energy Balance in Urban Areas – Recent Advances and Future Needs

Recent advances in understanding of the surface energy balance of urban areas, based on both experimental investigations andnumerical models, are reviewed. Particular attention is directedto the outcome of a COST-715 Expert Meeting held in April 2000,as well as experiments initiated by that action. In addition, recentcomplete parameterisations of urban effects in meso-scalemodels are reviewed. Given that neither the surface energybalance, nor its components, normally are directly measuredat meteorological stations, nor are there guidelines for theset-up of representative meteorological stations in urbanareas, this paper also provides recommendations to closethese gaps.     

HYDRAULIC GEOMETRY RELATIONSHIPS FOR URBAN STREAMS THROUGHOUT THE PIEDMONT OF NORTH CAROLINA1

ABSTRACT: Hydraulic geometry relationships, or regional curves, relate bankfull stream channel dimensions to watershed drainage area. Hydraulic geometry relationships for streams throughout North Carolina vary with hydrology, soils, and extent of development within a watershed. An urban curve that is the focus of this study shows the bankfull features of streams in urban and suburban watersheds throughout the North Carolina Piedmont. Seventeen streams were surveyed in watersheds that had greater than 10 percent impervious cover. The watersheds had been developed long enough for the streams to redevelop bankfull features, and they had no major impoundments. The drainage areas for the streams ranged from 0.4 to 110.3 square kilometers. Cross‐sectional and longitudinal surveys were conducted to determine the channel dimension, pattern, and profile of each stream and power functions were fitted to the data. Comparisons were made with regional curves developed previously for the rural Piedmont, and enlargement ratios were produced. These enlargement ratios indicated a substantial increase in the hydraulic geometry for the urban streams in comparison to the rural streams. A comparison of flood frequency indicates a slight decrease in the bankfull discharge return interval for the gaged urban streams as compared to the gaged rural streams. The study data were collected by North Carolina State University (NCSU), the University of North Carolina at Charlotte (UNC), and Charlotte Storm Water Services. Urban regional curves are useful tools for applying natural channel design in developed watersheds. They do not, however, replace the need for field calibration and verification of bankfull stream channel dimensions.     

郎酒热电联产厂滑坡的形成与稳定分析

本文从自然因素与人为因素两个方面分析了联产厂滑坡形成的原因，动力来源和激发条件，阐述了滑坡的形成过程和活动现状，根据计算结果提出了治理方案，治理工程于1999年7月实施完毕。经过治理后两年多的运行，观测资料反映治理效果良好，保证了该厂的正常工作。     

Organizational commitment,supervisory commitment,and employee outcomes in the Chinese context: proximal hypothesis or global hypothesis?

This study examines the relationship between organizational commitment and supervisory commitment (commitment to supervisor) in terms of their effects on employee outcomes in the Chinese context. Based on the principle of compatibility, we hypothesized that organizational commitment and supervisory commitment served as logical mediators (global hypothesis and proximal hypothesis) for predicting organization‐relevant and leader‐relevant outcomes respectively. Moreover, because of the impact of personalism in Chinese culture, we predicted that supervisory commitment also significantly influenced organization‐relevant outcomes, in addition to its effect on leader‐relevant outcomes. Two separate questionnaires were administered to 538 subordinates and their supervisors in Taiwanese companies. Structural equation modeling and hierarchical block regression analysis shows that the principle of compatibility and personalism can explain the proposed relationship in this study. Implications and research directions are discussed in light of Chinese culture for future investigation into organizational commitment and supervisory commitment. Copyright © 2003 John Wiley & Sons, Ltd.