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On composite foundation with different vertical reinforcing elements under vertical loading: a physical model testing study
Xian-zhi WANG, Jun-jie ZHENG, Jian-hua YIN
Journal of Zhejiang University-SCIENCE A (Applied Physics & Engineering), 2010, 11(2): 80-87.
https://doi.org/10.1631/jzus.A0900252
A physical model facility was designed, built, and setup for conducting model tests on a composite foundation in a soil ground. The model tests were carried out on a composite foundation with different combinations of vertical reinforcement elements in the same soil ground. Via the analysis of the collected data the characteristics of the composite foundation with different reinforcing elements were obtained, including the characteristics of load-settlement curves, column stresses, stresses of the inter-column soil, pile-soil stress ratio, and load-sharing ratios of columns and soil. Results from the model tests reveal the mechanism of a composite foundation with different reinforcing elements quantitatively. It is concluded that both a composite foundation with a combination of steel pipe pile and sand column and that with a combination of concrete pile and lime column have a higher bearing capacity than the composite foundation with only sand columns with the same conditions of soil ground and loading. A composite foundation with lime column and sand column embodies no much better performance than that with sand columns only.
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Lower extremity injuries in vehicle-pedestrian collisions using a legform impactor model
A. ABVABI, A. NASR, A. NOORPOOR, M. S. KIASAT
Journal of Zhejiang University-SCIENCE A (Applied Physics & Engineering), 2010, 11(2): 97-105.
https://doi.org/10.1631/jzus.A0900169
Though the bumper of a vehicle plays a major role in protecting the vehicle body against damage in low speed impacts, many bumpers, particularly in large vehicles, are too stiff for pedestrian protection. In designing a bumper for an automobile, pedestrian protection is as important as bumper energy absorption in low speed collisions. To prevent lower extremity injuries in car-pedestrian collisions, it is important to determine the loadings that car front structures impart on the lower extremities and the mechanisms by which injury is caused by these loadings. The present work was focused on gaining more insight into the injury mechanisms leading to both ligament damage and bone fracture during bumper-pedestrian collisions. The European Enhanced Vehicle-safety Committee (EEVC) legform impactor model was introduced and validated against EEVC/WG17 criteria. The collision mechanism between a bumper and this legform impactor was investigated numerically using LS-DYNA software. To identify the effect of the bumper beam material on leg injuries, four analyses were performed on bumpers that had the same assembly but were made from different materials.
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Performance of a single-stage Linde-Hampson refrigerator operating with binary refrigerants at the temperature level of −60 °C
Qin WANG, Kang CUI, Teng-fei SUN, Fu-sheng CHEN, Guang-ming CHEN, Kang CUI
Journal of Zhejiang University-SCIENCE A (Applied Physics & Engineering), 2010, 11(2): 115-127.
https://doi.org/10.1631/jzus.A0900208
The optimization of the performance of a single-stage Linde-Hampson refrigerator (LHR) operating with six different binary refrigerants (R23/R134a, R23/R227ea, R23/R236ea, R170/R290, R170/R600a and R170/R600) with ozone depletion potentials (ODPs) of zero was conducted using a new approach at the temperature level of −60 °C. Among these binary refrigerants, the 0.55 and the 0.6 mole fractions of R23 for R23/R236ea are the most prospective nonflammable ones for the medium and low suction pressure compressors, respectively. For these two kinds of compressors, the 0.6 and the 0.65 mole fractions of R170 for R170/R600, respectively, are the most prospective binary refrigerants with low global warming potentials (GWPs). The results of optimization of pressure levels indicate that the optimum low pressure value for coefficients of performance (COP) is achieved when the minimum temperature differences occur at both the hot and the cold ends of the recuperator at a specified composition and pressure ratio. Two useful new parameters, the entropy production per unit heat recuperated and the ratio of heat recuperating capacity to the power consumption of the compression, were introduced to analyze the exergy loss ratio in the recuperator. The new approach employed in this paper also suggests a promising application even to the optimization of the performance with multi-component refrigerants.
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Treatment and hydraulic performances of the NiiMi process for landscape water
Jian YANG, Liang-bo ZHANG, Yi-fan WU, Ya-yi WANG, Cui LI, Wen LIU
Journal of Zhejiang University-SCIENCE A (Applied Physics & Engineering), 2010, 11(2): 132-142.
https://doi.org/10.1631/jzus.A0900437
This paper describes the NiiMi process designed to treat landscape water. The main aim of the research was to investigate the feasibility of NiiMi for removing organic and nutriment materials from landscape water. During the batch-scale NiiMi operation, the removal rates of color ranged from 66.7%–80%, of turbidity from 31.7%–89.3%, of chemical oxygen demand (COD) from 7%–36.5%, of total phosphor (TP) from 43%–84.2%, of soluble phosphate from 42.9%–100%, of total nitrogen (TN) from 4.2%–46.7%, and of NH4+-N from 39.3%–100% at the hydraulic loading of 0.2 m3/(m2·d). Results showed that the removal efficiencies of COD, TP, soluble phosphate and TN decreased with the decline in the temperature. The NiiMi process had a strong shock loading ability for the removal of the organics, turbidity, TP, soluble phosphate, TN and NH4+-N. Three sodium chloride tracer studies were conducted, labeled as TS1, TS2, and TS3, respectively. The mean hydraulic retention times (mean HRTs) were 31 h and 28 h for TS1 and TS2, respectively, indicating the occurrence of a dead zone volume of 12% and 20% for TS1 and TS2, respectively. TS1 and TS2 displayed the occurrence of short-circuiting in the NiiMi system. The comparison results between TS1 and TS2 were further confirmed in the values obtained for some indicators, such as volumetric efficiency (e), short-circuiting (S), hydraulic efficiency (λ) and number of continuously stirred tank reactors (N).
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Factors influencing the formation of chlorination brominated trihalomethanes in drinking water
Huan WANG, Dong-mei LIU, Zhi-wei ZHAO, Fu-yi CUI, Qi ZHU, Tong-mian LIU
Journal of Zhejiang University-SCIENCE A (Applied Physics & Engineering), 2010, 11(2): 143-150.
https://doi.org/10.1631/jzus.A0900343
The formation of brominated trihalomethanes (THMs-Br) which is proved more carcinogenic than their chlorinated analogues reported was very different at various water qualities. This study was performed to assess the effects of water quality parameters (bromide concentration, pH value and ammonia concentration), chlorination conditions (chlorine dose, reaction time) and ratios of Br−/DOC and Br−/Cl2 consumption on the formation and distribution of THMs-Br in chlorination. The results showed good correlation between the bromine incorporation factor (BIF) n(Br) and Br−/Cl2 consumption ratio. The formation of total THM (TTHM) was found to decrease with increasing ammonia concentration but to increase with bromide concentration and pH value. The n(Br) trends were significantly affected by the presence of bromide concentration. The effects on the molar yields of THMs were more strongly influenced by bromide concentration and dissolved organic carbon (DOC) concentration than pH value and natural organic matter (NOM) source. High Br−/DOC and Br−/Cl2 favor the formation of THMs-Br over chlorinated THMs (THMs-Cl). The experimental data including the main parameters such as bromide, DOC, ammonia, pH and reaction time were used for developing the predictive model for THMs-Br.
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9 articles
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