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Aerodynamic stability of cable-supported bridges using CFRP cables
ZHANG Xin-jun, YING Lei-dong
Journal of Zhejiang University-SCIENCE A (Applied Physics & Engineering), 2007, 8(5): 693-698.
https://doi.org/10.1631/jzus.2007.A0693
To gain understanding of the applicability of carbon fiber reinforced polymer (CFRP) cable in cable-supported bridges, based on the Runyang Bridge and Jinsha Bridge, a suspension bridge using CFRP cables and a cable-stayed bridge using CFRP stay cables are designed, in which the cable’s cross-sectional area is determined by the principle of equivalent axial stiffness. Numerical investigations on the aerodynamic stability of the two bridges are conducted by 3D nonlinear aerodynamic stability analysis. The results showed that as CFRP cables are used in cable-supported bridges, for suspension bridge, its aerodynamic stability is superior to that of the case using steel cables due to the great increase of the torsional frequency; for cable-stayed bridge, its aerodynamic stability is basically the same as that of the case using steel stay cables. Therefore as far as the wind stability is considered, the use of CFRP cables in cable-supported bridges is feasible, and the cable’s cross-sectional area should be determined by the principle of equivalent axial stiffness.
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Removal and transformation of organic matter during soil-aquifer treatment
ZHAO Qing-liang, XUE Shuang, YOU Shi-jie, WANG Li-na
Journal of Zhejiang University-SCIENCE A (Applied Physics & Engineering), 2007, 8(5): 712-718.
https://doi.org/10.1631/jzus.2007.A0712
This study investigated the removal and transformation of organic matter through laboratory-scale soil-aquifer treatment (SAT) soil columns over a 110-day period. Reductions in total organic carbon (TOC), dissolved organic carbon (DOC), biodegradable dissolved organic carbon (BDOC), nonbiodegradable dissolved organic carbon (NBDOC) and absorbance of ultraviolet light at 254 nm (UV-254) averaged 71.46%, 68.05%, 99.31%, 33.27% and 38.96% across the soil columns, respectively. DOC/TOC ratios increased slightly with depth while BDOC/DOC ratios showed a converse trend. DOC exiting the soil-column system contained only a very small biodegradable fraction. SAT decreased the concentration of DOC present in feed water but increased its aromaticity, as indicated by specific ultraviolet light absorbance (SUVA), which increased by 50%~115% across the soil columns, indicating preferential removal of non-aromatic DOC during SAT. Overall, laboratory-scale SAT reduced trihalomethane formation potential (THMFP), although specific THMFP increased. THMFP reduction was dominated by removal in chloroform. All samples exhibited a common general relationship with respect to weight: chloroform>dichlorobromomethane >dibromochloromethane>bromoform.
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Numerical simulation of a gas pipeline network using computational fluid dynamics simulators
SELEZNEV Vadim
Journal of Zhejiang University-SCIENCE A (Applied Physics & Engineering), 2007, 8(5): 755-765.
https://doi.org/10.1631/jzus.2007.A0755
This article describes numerical simulation of gas pipeline network operation using high-accuracy computational fluid dynamics (CFD) simulators of the modes of gas mixture transmission through long, multi-line pipeline systems (CFD-simulator). The approach used in CFD-simulators for modeling gas mixture transmission through long, branched, multi-section pipelines is based on tailoring the full system of fluid dynamics equations to conditions of unsteady, non-isothermal processes of the gas mixture flow. Identification, in a CFD-simulator, of safe parameters for gas transmission through compressor stations amounts to finding the interior points of admissible sets described by systems of nonlinear algebraic equalities and inequalities. Such systems of equalities and inequalities comprise a formal statement of technological, design, operational and other constraints to which operation of the network equipment is subject. To illustrate the practicability of the method of numerical simulation of a gas transmission network, we compare computation results and gas flow parameters measured on-site at the gas transmission enterprise.
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Computation of rolling resistance caused by rubber hysteresis of truck radial tire
MA Gai-ling, XU Hong, CUI Wen-yong
Journal of Zhejiang University-SCIENCE A (Applied Physics & Engineering), 2007, 8(5): 778-785.
https://doi.org/10.1631/jzus.2007.A0778
Applying the results of stress and strain calculated by 3D finite element model of truck radial tire 11.00R20, a MATLAB program used to compute rolling resistance of the tire caused by hysteresis rolling resistance (HRR) is worked out. The HRR distribution on different part of tire section, and the effects of speed, load, internal pressure and the width of the rim on HRR are analyzed. The analysis results showed that energy loss produced by tread rubber contributes the most part to HRR of the whole tire, and that to decrease the HRR, the hysteresis factor of the tread rubber should be reduced, and the distribution of the stress and strain on the section be optimized.
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Novel high torque bearingless two-sided rotary ultrasonic motor
LI Xia, CHEN Wei-shan, XIE Tao, LIU Jun-kao
Journal of Zhejiang University-SCIENCE A (Applied Physics & Engineering), 2007, 8(5): 786-792.
https://doi.org/10.1631/jzus.2007.A0786
Applications are limited at present because the currently available ultrasonic motors (USMs) do not provide sufficiently high torque and power. The conventional travelling-wave USM needs the bearing to support, which required lubricant. To solve the above problem, a bearingless travelling-wave USM is designed. First, a novel structure of the two-sided USM consisting of a two-sided teeth stator and two disk-type rotors is designed. And the excitation principle of the two-sided travelling-wave USM is analyzed. Then, using ANSYS software, we set up the model of the stator to predict the excitation frequency and modal response of the stator. The shape of the vibration mode was obtained. Last, the load characteristics of the USM are measured using experimental method. The maximum stall torque and the no-load speed were obtained. The results showed that the characteristics of the two-sided USM are better than those of the conventional one-sided USM.
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Application of grey relational analysis in sheet metal forming for multi-response quality characteristics
XIE Yan-min, YU Hu-ping, CHEN Jun, RUAN Xue-yu
Journal of Zhejiang University-SCIENCE A (Applied Physics & Engineering), 2007, 8(5): 805-811.
https://doi.org/10.1631/jzus.2007.A0805
The theory of grey systems is a new technique for performing prediction, relational analysis and decision making in many areas. In this paper, the use of grey relational analysis for optimizing the square hole flanging process parameters with considerations of the multiple response (the average flanging height, regular flanging and maximum strain) is introduced. Various flanging parameters, such as the blank inner radius rb, blank inner width B0, are considered. An orthogonal array is used for the experimental design. Multiple response values are obtained using finite element analysis (FEA). Optimal process parameters are determined by the grey relational grade obtained from the grey relational analysis for multi-performance characteristics (flanging height, regular flanging and maximum strain). Analysis of variance (ANOVA) for the grey relational grade is implemented. The results showed good agreement with the experiment result. Grey relational analysis can be applied in multiple response optimization designs.
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Recent advances in nonlinear control technologies for shape memory alloy actuators
SREEKUMAR M., SINGAPERUMAL M., NAGARAJAN T., ZOPPI M., MOLFINO R.
Journal of Zhejiang University-SCIENCE A (Applied Physics & Engineering), 2007, 8(5): 818-829.
https://doi.org/10.1631/jzus.2007.A0818
This paper reviews recent developments in nonlinear control technologies for shape memory alloy (SMA) actuators in robotics and their related applications. SMA possesses large hysteresis, low bandwidth, slow response, and non-linear behavior, which make them difficult to control. The fast response of the SMA actuator mostly depends upon, (1) type of controller, (2) rate of addition and removal of heat, and (3) shape or form of the actuator. Though linear controllers are more desirable than nonlinear ones, the review of literature shows that the results obtained using nonlinear controllers were far better than the former one. Therefore, more emphasis is made on the nonlinear control technologies taking into account the intelligent controllers. Various forms of SMA actuator along with different heating and cooling methods are presented in this review, followed by the nonlinear control methods and the control problems encountered by the researchers.
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22 articles
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