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Gu L.,Hohai University | Li Q.,Urban Engineer | Hua Z.,Hohai University | Wang L.,Hohai University | Yuan H.,Hohai University
Journal of Hydraulic Research | Year: 2015

Complex thermal-hydraulic phenomena associated with stratified shear flows in braided rivers have not yet been characterized. This paper fills this knowledge gap and reports extensive laboratory studies of both isothermal flow and thermal stratified flow with different velocity ratios between two layers. Results show that the high temperature zone shifted from the outer bank to the inner bank along an anabranch, but was reversed in the high-velocity zone. It is found that circulation cell structures, cross-sectional velocity distributions, shapes of separation zones, and locations of strong turbulent intensity in thermally stratified flow change with the velocity ratio. A comparative analysis of thermal stratified flow with isothermal flow is given. In particular, it is shown that the main lateral circulation cell was reversed in the thermal stratified flow compared with that in the isothermal flow. © 2015 International Association for Hydro-Environment Engineering and Research

Zhang X.R.,Harbin Institute of Technology | Li W.G.,Harbin Institute of Technology | Li W.G.,Urban Engineer | Ren P.F.,Harbin Institute of Technology
Advanced Materials Research | Year: 2013

This study evaluated and optimized the UV/ chlorine process for natural organic matters (NOMs) removal using response surface methodology (RSM). The effects of both the primary and secondary interactions of the reaction variables, including initial chlorine concentration (X1), UV radiation time (X2) and pH value (X3), were examined. A satisfactory prediction response model (R2=0.999) was obtained, indicating the reliability of the methodology. The optimum condition obtained by CCD were 4.5 mg·L-1 initial chlorine concentration, 7 min UV radiation time and pH 6.7. Under the optical condition, the maximum TOC removal was 48% and TOC concentration was only 2.6 mg·L-1. The UV/ chlorine process as a novel AOP has many advantages for drinking water treatment, in terms of less chemical consumption, shorter reaction time and simpler technology. © (2013) Trans Tech Publications, Switzerland.

Xu R.,Harbin Institute of Technology | Xu R.,Jinan Municipal Engineering Design & Research Institute Group Co. | Xu Y.,Harbin Institute of Technology | Xu Y.,Urban Engineer | And 5 more authors.
Journal of Harbin Institute of Technology (New Series) | Year: 2015

The overall purpose of this research is to examine the impact of untreated sedimentation tank sludge water (USTSW) recycle on water quality during treatment of low turbidity water in coagulation-sedimentation processes. 950 mL of raw water and different concentrations of 50 mL USTSW are injected into six 1000 mL beakers without coagulant. The results indicate that USTSW characterized as accumulated suspended solids and organic matter has active ingredients, which possess the equivalent function of coagulant. The optimal blended water turbidity is in the range of 10-20 NTU, within which USTSW recycle achieves the highest save coagulant rate. The mechanism of strengthening coagulation effect when USTSW recycle mainly depends on the chemical effect and physical effect. What is more, through scanning electron microscopy (SEM), it is found that the floc structures with USTSW recycle are more compact than those without USTSW recycle. Besides, the water quality parameters of color, NH3-N, CODMn, UV254, total aluminum, total manganese when USTSW recycle is better than the raw water without recycle, indicating that USTSW recycle can improve water quality with strengthening coagulation effect. ©, 2015, Harbin Institute of Technology. All right reserved.

Tutesigensi A.,University of Leeds | Phung B.N.,Urban Engineer
Proceedings of Institution of Civil Engineers: Management, Procurement and Law | Year: 2011

The Vietnamese construction industry has a poor health and safety (H&S) record. H&S performance is influenced by, among other things, stakeholders' attitude. Construction site workers are major stakeholders in H&S. If attitude to rights and responsibilities in relation to H&S among construction workers is understood, it may be managed to improve H&S performance. Against this background, a questionnaire survey of 408 construction workers in Vietnam was undertaken to measure the workers' attitude to their rights and responsibilities and to establish the key factors that influence it. The results suggest that construction workers have, generally, a positive attitude to their rights and responsibilities. The results also suggest that there is significant association between the worker's attitude to H&S and gender, number of dependants and amount of training. Furthermore, the results suggest that there is no significant association between the worker's attitude and their age, marital status, level of education and experience. The survey leads to the conclusion that H&S performance in the Vietnamese construction industry could be improved by adopting a holistic approach to managing H&S, promoting mixed-gender work teams, and designing regular and lifelong H&S training programmes that provide for, among other things, understanding of social consequences of poor H&S performance.

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