WIND DRIVEN RAIN DISTRIBUTIONS AROUND STREET CANOPIES1

ABSTRACT: Wind driven raindrop tracking is used to investigate the microscale redistribution of wind driven rainfalls in street canopies by combining a Eulerian wind flow model and a Lagrangian raindrop tracking model. The former conducts large eddy simulations of the turbulent flows in street canopies, and the latter performs raindrop trajectory calculations by releasing a large number of raindrops into the computational domain. The wind speed model is verified with available wind tunnel measurement. Twenty sets of simulations are carried out for various building configurations and driving rain angles. The simulated results show that the trajectories of smaller raindrops are more slanting and more influenced by the multibuilding perturbed flow field. Impingement of raindrops on the building envelope increases from bottom to top. The height of the front building is a significant factor affecting wind driven rain redistribution. Distinct nonuniform spatial rainfall distributions are found for scenarios with high building configurations and low driving rain angles. The simulated results are further integrated to assess the effect of real raindrop size distributions by weighing the volumetric fraction of a range of drop sizes. There is about 10 percent variation in spatial extent of street canopies. An overall 5 to 17.4 percent increase of the rainfall amount in the upwind zone is observed.     

Solvent extraction and soil washing treatment of contaminated soils from wood preserving sites: Bench‐scale studies

Bench‐scale solvent extraction and soil washing studies were performed on soil samples obtained from three abandoned wood preserving sites included in the National Priority List. The soil samples from these sites were contaminated with high levels of polyaromatic hydrocarbons (PAHs), pentachlorophenol (PCP), dioxins, and heavy metals. The effectiveness of the solvent extraction process was assessed using liquefied propane or dimethyl ether as solvents over a range of operating conditions. These studies have demonstrated that a two‐stage solvent extraction process using dimethyl ether as a solvent at a ratio of 1.61 per kg of soil could decrease dioxin levels in the soil by 93.0 to 98.9 percent, and PCP levels by 95.1 percent. Reduction percentages for benzo(a)pyrene (BaP) potency estimate and total detected PAHs were 82.4 and 98.6 percent, respectively. Metals concentrations were not reduced by the solvent extraction treatment. These removal levels could be significantly improved using a multistage extraction system. Commercial scale solvent extraction using liquefied gases costs about $220 per ton of contaminated soil. However, field application of this technology at the United Creosote site, Conroe, Texas, failed to perform to the level observed at bench scale due to the excessive foaming and air emission problem. Soil washing using surfactant solution and wet screening treatability studies were also performed on the soil samples in order to assess remediation strategies for sites. Although aqueous phase solubility of contaminants seemed to be the most important factor affecting removal of contaminants from soil, surfactant solutions (3 percent by weight) having nonionic surfactants with hydrophile‐lipophile balance (HLB) of about 14 (Makon‐12 and Igepal CA 720) reduced the PAH levels by an average of 71 percent, compared to no measurable change when pure deionized water was used. Large fractioza of clay and silt (<0.06mm), high le!ezielsof orgaizic contami‐ nants and hzimic acid can makesoil washing less applicable.     

Transport and survival of viruses in the subsurface—processes,experiments, and simulation models

The remediation of groundwater contaminated with waterborne pathogens, in particular with viruses, is based on their probable or actual ability to be transported from the source of origin to a point of withdrawal while maintaining the capacity to cause infections. The transport is often associated with both the unsaturated and saturated subsurface composed of varying geological settings with commensurate hydrogeological variability. Included among the most important hydrogeological factors that can be used to evaluate viral transport are the flux of moisture in the unsaturated zone, the media through which the particles travel, the length of the flow path, and the time of travel. With respect to the movement and inactivation of viruses in the subsurface, the vadose zone can provide an effective barrier for movement into groundwater and for the protection of downgradient points of withdrawal and use. Models developed to predicate viral transport in soil and groundwater are introduced, including screening models and more sophisticated predictive numerical models. As evidenced by the exponential growth of virus transport research in the literature, as well as a continuing interest in human health, the subject will continue to be one of critical importance to professionals active in the development, treatment, and conveyance of groundwater in the future. © 2005 Wiley Periodicals, Inc.     

The dispositional approach to job satisfaction: more than a mirage,but not yet an oasis

This paper readdresses the person–situation debate in organizational research. The well‐known arguments of Davis‐Blake and Pfeffer (1989) are evaluated in light of research and theory that has transpired since the publication of their original critique. A new dispositional model of job satisfaction is then proposed. The model is based on several informational and action steps including exposure to work events and condition, as well as the evaluation, memory, retrieval, and expression of affect in the organizational context. Using this model, we discuss how dispositional affect can influence what is experienced in the workplace, how one evaluates it, and how it is expressed to others, including organizational researchers. Copyright © 2005 John Wiley & Sons, Ltd.     

Leader–member exchange and job performance: The effects of taking charge and organizational tenure

We theorized and tested the mechanisms by which leader–member exchange (LMX) quality is associated with job performance. The results obtained using 212 employee–supervisor pairs from eight Chinese companies indicated that LMX quality had an indirect and positive relationship with taking charge via psychological empowerment and had an indirect and positive relationship with job performance via taking charge. In addition, organizational tenure significantly moderated the relationship between taking charge and job performance, such that the positive effect of taking charge on job performance became weaker as organizational tenure increased. Furthermore, organizational tenure significantly moderated the indirect positive relationship between LMX quality and job performance via taking charge; the indirect effect became weaker as organizational tenure increased. These results suggest that organizations should encourage managers to develop high‐quality LMX with their subordinates, which may make them feel more empowered and engage in more taking charge, and result in better job performance. Copyright © 2014 John Wiley & Sons, Ltd.