Current Issue : July - September Volume : 2012 Issue Number : 3 Articles : 5 Articles
Traffic safety and mobility of roadway work zones have been considered to be one of the major concerns in highway traffic safety\r\nand operations in Florida. Dynamic lane merging (DLM) systemsââ?¬â?ITS-based lane management technologyââ?¬â?were introduced\r\nby several states in an attempt to enhance both safety and mobility of roadway work zones. Two forms of lane merging, namely,\r\nthe early merge and the late merge were designed to advise drivers on definite merging locations. Up to date, there are no studies\r\nthat contrast both merging schemes under matching work zone settings. This study simulates a two-to-one work zone lane closure\r\nconfiguration under three different Maintenance of Traffic (MOT) plans in VISSIM. The first MOT is the conventional plans used\r\nin Floridaââ?¬â?¢s work zones, the second MOT is a simplified dynamic early merging system (early SDLMS), and the third MOT is a\r\nsimplified dynamic late merging systems (late SDLMSs). Field data were collected to calibrate and validate the simulation models.\r\nSimulation results indicated that overall, under different levels of driversââ?¬â?¢ compliance rate and different percentages of trucks in\r\nthe traffic composition, the early SLDMS outperformed the conventional MOT and the late SDLMS in terms of travel times and\r\nthroughputs....
This work addresses the development of a new four-noded rectangular Mindlin plate bending element (MP4C) with a crack\r\nwhich consists of three degrees of freedom (DOF) at each corner node. The crack in the element is assumed to be not closed\r\nand nonpropagating. The crack affects the elastic strain energy and the flexibility matrix of the element, whereas the mass matrix\r\nremains unchanged. The complete element stiffness matrix is constructed as the inverse of the combined flexibility matrix of both\r\nnoncracked and cracked elements. To evaluate the behavior of the proposed cracked Mindlin plate element, numerical examples\r\nare provided. They are based on developing user subroutines in ABAQUS. The finite element analysis results using the developed\r\nplate element are in excellent agreement with those reported in previous work. The cracked plate element developed in this paper\r\nprovides a simple and robust approach to model the real service conditions in plate-like structures....
A driver usually controls the vehicle according to only the information from the nearest leader vehicle. If the information from the\r\nother leader vehicles is also available, the driver can control the vehicle more adequately. The aim of this study is to discuss the effectiveness\r\nof the information from the other leader vehicles than the nearest one for the traffic flow. For this purpose, the traffic flowis\r\nmodeled by using the Chandler-type multi-vehicle-following model. This model changes the vehicle acceleration rate according to\r\nthe velocity differences between the vehicle and itsmultileader vehicles. After the model stability analysis, the traffic flow simulation\r\nis performed. The results reveal that the stable region of the model parameters expands according to the increase of the number of\r\nthe leader vehicles....
Conjunctive management of water resources involves coordinating use of surface water and groundwater resources. Very few\r\nsimulation/optimization (S-O) models for stream-aquifer system management have included detailed interactions between\r\ngroundwater, streams, and reservoir storage. This paper presents an S-O model doing that via artificial neural network simulators\r\nand genetic algorithm optimizer for multiobjective conjunctive water use problems. The model simultaneously addresses all\r\nsignificant flows including reservoir-stream-diversion-aquifer interactions in a more detailed manner than previous models. The\r\nmodel simultaneously maximizes total water provided and hydropower production. A penalty function implicitly poses constraints\r\non state variables. The model effectively finds feasible optimal solutions and the Pareto optimum. Illustrated is application for\r\nplanning water resource and minihydropower system development....
The effectiveness of externally bonded sprayed glass fiber reinforced polymer (Sprayed GFRP) in shear strengthening of RC beams\r\nunder quasi-static loading is investigated. Different techniques were utilized to enhance the bond between concrete and Sprayed\r\nGFRP, involving the use of through bolts and nuts paired with concrete surface preparation through sandblasting and through the\r\nuse of a pneumatic chisel prior to Sprayed GFRP application. It was found that roughening the concrete surface using a pneumatic\r\nchisel and using through bolts and nuts were the most effective techniques. Also, Sprayed GFRP applied on 3 sides (U-shaped) was\r\nfound to be more effective than 2-sided Sprayed GFRP in shear strengthening. Sprayed GFRP increased the shear load-carrying\r\ncapacity and energy absorption capacities of RC beams. It was found that the load-carrying capacity of strengthened RC beams was\r\nrelated to an effective strain of applied Sprayed GFRP. This strain was related to Sprayed GFRP configuration and the technique\r\nused to enhance the concrete-FRP bond. Finally, an equation was proposed to calculate the contribution of Sprayed GFRP in the\r\nshear strength of an RC beam....
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