Effects of plate temperature on heat transfer and emissions of impinging flames

Experiments were conducted to investigate the heat transfer and CO/NO_X emissions of a premixed LPG/air circular flame jet impinging upwards normally to a flat rectangular plate. Temperatures of the impingement plate were controlled by cooling water at 38 °C, 58 °C and 78 °C which was circulating at its back in order to create different plate temperatures. Under each plate temperature, the effects of Reynolds number (Re), equivalence ratio (Ф) and nozzle-to-plate distance (H) on the heat transfer and CO/NO_X emissions were examined. The Re was selected to be 500, 1000 and 1500 to ensure laminar flame jets. The values of Ф were chosen to cover fuel-lean, stoichiometric and fuel-rich conditions. The H varied from 3d to 7d with an interval of 1d.The flame-side temperature of the impingement plate is enhanced when the cooling water temperature increases, but the temperature difference across the impingement plate is reduced. Heat transfer from the flame to the plate is suppressed at higher cooling water temperature. The heat transfer rate is the highest when the cooling water temperature is at 38 °C and the lowest heat flux is obtained at 78 °C. At the highest cooling water temperature of 78 °C, the CO emission is reduced whereas the NO_X emission is enhanced. However, this trend is reversed at the lowest cooling water temperature of 38 °C.     

Tuning of structural color using a dielectric actuator and multifunctional compliant electrodes

We have developed electrically conducting silicone elastomer nanocomposites that serve both as compliant electrodes in an electrostatic actuator and, at the same time, as optically active elements creating structural color. We demonstrate the capabilities of our setup by actuating an elastomeric diffraction grating and colloidal-crystal-based photonic structures.     

A local boundary integral-based meshless method for Biot's consolidation problem

Traditional numerical techniques such as FEM and BEM have been successfully applied to the solutions of Biot's consolidation problems. However, these techniques confront some difficulties in dealing with moving boundaries. In addition, pre-designing node connectivity or element is not an easy task. Recently, developed meshless methods may overcome these difficulties. In this paper, a meshless model, based on the local Petrov–Galerkin approach with Heaviside step function as well as radial basis functions, is developed and implemented for the numerical solution of plane strain poroelastic problems. Although the proposed method is based on local boundary integral equation, it does not require any fundamental solution, thus avoiding the singularity integral. It also has no domain integral over local domain, thus largely reducing the computational cost in formulation of system stiffness. This is a truly meshless method. The solution accuracy and the code performance are evaluated through one-dimensional and two-dimensional consolidation problems. Numerical examples indicate that this meshless method is suitable for either regular or irregular node distributions with little loss of accuracy, thus being a promising numerical technique for poroelastic problems.     

A Study of the Partially Adaptive Concentric Ring Array

Concentric ring arrays can provide effective beamforming and achieve frequency invariant beampatterns. For long range signal acquisition, the array has a large number of array elements, and partial adaptation is often necessary to increase tracking ability and reduce computation. The topic of this paper is the study of a partially adaptive concentric ring array for three-dimensional audio signal acquisition. We develop the partially adaptive array through partition matrix formulation, provide the associated adaptive structure, and derive the steady state residual interference and noise power that can serve as a criterion to evaluate different partition structures. A comparison of several partition schemes using the criterion is given, and the theoretical results are supported by simulations. The research is supported by US AFOSR under contract FA9550-04-C-0058 and partially supported by the Polytechnic University of Puerto Rico.     

Chemical properties and antioxidant activity of exopolysaccharides from mycelial culture of Cordyceps sinensis fungus Cs-HK1

Exopolysaccharide (EPS) was produced in a mycelial liquid culture of the Cordyceps sinensis fungus, Cs-HK1, at a rate proportional to mycelial growth. The crude EPS isolated from the culture medium by ethanol precipitation contained 65–70% sugar and about 25% protein, suggesting that the EPS was composed of polysaccharide–protein complexes. It exhibited a wide molecular weight (MW) range from about 5 kDa to more than 200 kDa. The intrinsic viscosity as an index of average MW of EPS, increased during the period of rapid mycelial growth to 11.0 dL/g on day 5, and remained relatively stable between day 5 to day 8 (stationary growth period). Both infrared spectrometry of EPS and gas chromatography of acetylated EPS suggested that the EPS had a β-d-glucan backbone. The EPS showed moderate antioxidant activities with a Trolox equivalent antioxidant capacity of 35–40 μmol Trolox/g and a ferric reducing ability of plasma of 50–52 μmol Fe(II)/g.     

Heavy metals concentrations of surface dust from e-waste recycling and its human health implications in southeast China

The recycling of printed circuit boards in Guiyu, China, a village intensely involved in e-waste processing, may present a significant environmental and human health risk. To evaluate the extent of heavy metals (Cd, Co, Cr, Cu, Ni, Pb, Zn) contamination from printed circuit board recycling, surface dust samples were collected from recycling workshops, adjacent roads, a schoolyard, and an outdoor food market. ICP-OES analyses revealed elevated mean concentrations in workshop dust (Pb 110,000, Cu 8360, Zn 4420, and Ni 1500 mg/kg) and in dust of adjacent roads (Pb 22,600, Cu 6170, Zn 2370, and Ni 304 mg/kg). Lead and Cu in road dust were 330 and 106, and 371 and 155 times higher, respectively, than non e-waste sites located 8 and 30 km away. Levels at the schoolyard and food market showed that public places were adversely impacted. Risk assessment predicted that Pb and Cu originating from circuit board recycling have the potential to pose serious health risks to workers and local residents of Guiyu, especially children, and warrants an urgent investigation into heavy metal related health impacts. The potential environmental and human health consequences due to uncontrolled e-waste recycling in Guiyu serves as a case study for other countries involved in similar crude recycling activities.     

An evaluation of the psychometric properties of the Smoking Self-Efficacy Questionnaire (SEQ-12) among Chinese cardiac patients who smoke

Smoking cessation can reduce both morbidity and mortality among patients who have heart disease. China has the largest number of smokers in the world, and most smokers have low motivation to quit. Regular smoking cessation services are almost nonexistent in China, and little is known about the psychometric properties of instruments in assessing smoking self-efficacy in Chinese, whose cultures differ greatly from those of Westerners. The present study tested the psychometric properties of the Chinese version of the Smoking Self-Efficacy Questionnaire (SEQ-12) among 1,841 Chinese smokers who had heart disease, including (a) factorial structure using confirmatory factor analysis, (b) reliability with Cronbach's alpha, (c) concurrent validity, and (d) predictive validity of successful quitting. Confirmatory factor analysis of the SEQ-12 revealed a modified two-factor model that provided a good fit to the data; item 6 ("urge to smoke") was an indicator for the external stimuli subscale rather than for the internal stimuli subscale. Internal consistency coefficients (.77 for external stimuli and .88 for internal stimuli) were acceptable. Baseline self-efficacy scores were significantly associated positively with stage of readiness to quit, and negatively with cigarettes smoked per day and Fagerstrom Test for Nicotine Dependence (FTND) score. Multivariate logistic regression analysis showed that successful quitting at 1 month and at 3 months were predicted by higher external stimuli score, fewer cigarettes smoked per day, lower FTND scores, and being in the intervention group. We concluded that the Chinese version of the SEQ-12 is a valid and reliable instrument for Chinese cardiac patients who smoke. The SEQ-12 can be used to assess smokers' self-efficacy so that appropriate smoking cessation interventions can be provided.     

旧概念与新环境(八):洛克的“自由”

洛克的政治理论是英语文明主流,强调个人自由,认为私产是自由的保障,而保护私产是政府的主要职能。城市规划以公益名义约束私产,但在自由社会中,公益只可来自政治博弈,因此纷争不断。本文以区划法的公安权力去演绎在洛克式个人自由之下私利与公益的死结。结论是,中国应坚持土地产权国有。     

基于混沌调频信号的超宽带穿墙SAR成像

混沌调频信号具有良好的自相关特性,又类似随机信号,具有较强的抗干扰性能。该文将基于Bernoulli映射的混沌调频信号用于超宽带穿墙雷达成像,建立了信号模型,分析了混沌调频穿墙雷达系统的目标检测性能,分辨能力和抗墙壁多径干扰能力,并与线性调频雷达系统进行了比较。仿真结果表明,与线性调频信号相比,混沌调频信号用于穿墙雷达系统可获得较好的目标检测性能,更好的分辨能力,而且具有抗墙壁多径干扰能力。     

Entropic Risk Analysis by a High Level Decision Support System for Construction SMEs

The method of entropy has been useful in evaluating inconsistency on human judgments. This paper illustrates an entropy-based decision support system called e-FDSS to the solution of multicriterion risk and decision analysis in projects of construction small and medium enterprises (SMEs). It is optimized and solved by fuzzy logic, entropy, and genetic algorithms. A case study demonstrated the use of entropy in e-FDSS on analyzing multiple risk criteria in the predevelopment stage of SME projects. Survey data studying the degree of impact of selected project risk criteria on different projects were input into the system in order to evaluate the preidentified project risks in an impartial environment. Without taking into account the amount of uncertainty embedded in the evaluation process; the results showed that all decision vectors are indeed full of bias and the deviations of decisions are finally quantified providing a more objective decision and risk assessment profile to the stakeholders of projects in order to search and screen the most profitable projects.