International Journal of Civil Engineering
Volume:12 Issue: 3, Sep 2014

The unsteady flow in porous medium of a viscous incompressible fluid bounded by two parallel porous plates is studied with heat transfer. A uniform and constant pressure gradient is applied in the axial direction whereas a uniform suction and injection are applied in the direction normal to the plates. The two plates are kept at constant and different temperatures and the viscous dissipation is not ignored in the energy equation. The effect of the porosity of the medium and the uniform suction and injection velocity on both the velocity and temperature distributions are investigated.

In different projects the speed of different machinery can be estimated using manufacturer's handbooks and a number of modification factors to consider the environmental effects, type of the project and status of site management. Since the statuses of different factors of the domestic projects are totally different from those of the international projects, there is a wide discrepancy between the determined speed by handbooks and the actual values in the domestic projects. This paper is aimed to develop a fuzzy system to estimate soil excavation rates at earthmoving jobsites. The proposed fuzzy system is based on IF-THEN rules; a genetic algorithm improves the overall accuracy. The obtained results clearly revealed the capability and applicability of the proposed system to properly estimate soil excavation speed. The average error of fuzzy system, handbook method and nearest neighbor interpolation are 10, 92 and 32 percent, respectively.

Road transportation by way of automobiles is a very convenient means of transportation. Today, the most detrimental consequence of developing transportation systems in a country is traffic accident that places a huge financial burden on society. This paper investigates the role of information systems in transportation safety that leads to improved planning and operation of the transportation system through the application of new technologies. Current methods for identification of segments of roads with high potential of accident are based on statistical approaches. Since there are not accident records for newly built roads, these methods cannot be used for regional roads that are recently built. This paper presents a GIS based Neuro-Fuzzy modeling for identification of road hazardous zones. The results of proposed approach are compared with statistical methods. It is shown that this method is a cheaper but at the same time robust means of analyzing the level of hazard associated with each road segment under consideration, specially when data are uncertain and incomplete.

Rutting in asphalt concrete is a very common form of distress in asphalt concrete pavement which unfortunately has been incurable to date. One of the prime reasons of rutting is attributed to the behaviour of asphalt binder at elevated temperature. This study has investigated the performance of polypropylene fibres modified asphalt concrete mix against rutting. Two types of asphalt concrete samples were prepared namely control samples (those without polypropylene addition) and modified samples (with polypropylene modification). Marshall Mix Design was used for determining the Optimum Asphalt Content for both sample types. Slab asphalt concrete specimens of dimensions 300 mm length and breadth and 50 mm thickness were prepared for both control and modified samples. These samples were then tested in the Wheel Tracking Device for rutting susceptibility test. The samples were tested at four temperatures i.e. 40°C, 50°C, 55°C and 60°C and under the application of 10 000 load passes of 700N of axle load.. The polypropylene fibres were found to increase the Marshall Stability by almost 25%. The fibres were also determined to be effective against rutting at elevated temperatures while the modification was found to increase the Indirect Tensile strength by stiffening the mix at high temperature however at low temperature, the modification failed to perform effectively.

A structural model for urban arterial road is proposed. It describes the road traffic dynamics in a disaggregated way. The structural model mainly includes: (1) a link traffic model that tracks the traffic waves cyclically. Traffic waves within each cycle are captured by three characteristic points. These points are formed by the encounter of different traffic waves. (2) a proportional line model which is used to split the overall outflow into different turning flow. The model is derived directly from first-in-first-out (FIFO) principle. (3) a spillover component that deals with channelized section queue overflow and (4) a traffic flow performance index component that outputs macroscopic and microscopic level indexes. These indexes include delay, stops, queue length and vehicle trajectory, travel time. The former three can be used in traffic flow optimization and the latter two are valuable in vehicle emission evaluation. Simulation results show that with the increasing of numerical resolution, traditional CTM model gradually converges to our model.

The previous studies show that a high percentage of traffic accidents take place in two-lane rural highways and most of which happen at horizontal curves. Meanwhile the horizontal alignment is often subject to hard topographic conditions where because of economic aspects designers are forced to design horizontal curves at grades. Vertical angle of longitudinal slope reduces the normal force of vehicle on road and friction force in tire-pavement surface will decrease. This leads to a lack of sufficient driver control over the vehicle especially if the curve with small radius is located at downgrade. In this paper, the suitability of operating speed and lateral friction coefficient as geometric design criteria for horizontal curves in downgrades are studied with regard to traffic safety and vehicle stability. The investigation of speed reduction of the vehicles running on a horizontal curve at downgrade as a response of driver behavior and the use of friction ellipse theory give the available friction coefficient. Whereas the dynamic analysis of forces applied on the vehicle in curve which is located at downgrade if combined with operating speed results in the required coefficient of lateral friction. Finally, a comparison of these two parameters based on safety evaluation criteria gives an estimation of actual safety level in designing horizontal curve at downgrades with regard to AASHTO’s data in horizontal curve design.

An analytical nonlinear stress-strain model and a microscopic damage index for confined and unconfined concretes together with a macroscopic damage index for reinforced concrete (RC) structures under cyclic loading are proposed. In order to eliminate the problem of scale effect, an adjustable finite element computer program was generated to simulate RC structures subjected to cyclic loading. By comparing the simulated and experimental results of tests on the full-scale structural members and concrete cylindrical samples, the proposed stress-strain model for confined and unconfined concretes under cyclic loading was accordingly modified and then validated. The proposed model has a strong mathematical structure and can readily be adapted to achieve a higher degree of precision by modifying the relevant coefficients based on more precise tests. To apply the proposed damage indices at the microscopic and macroscopic levels, respectively, stress-strain data of finite elements (confined and unconfined concrete elements) and moment-curvature data of critical section are employed. The proposed microscopic damage index can easily be calculated by using the proposed simple analytic nonlinear stress-strain model for confined and unconfined concretes. The proposed macroscopic damage index is based on the evaluation of nonlinear local degradation of materials and taking into account the pseudo-plastic hinge produced in the critical section of the structural element. One of the advantages of the macroscopic damage index is that the moment-curvature data of the critical section is sufficient in itself and there is no need to obtain the force-displacement data of the structural member.

We consider the problem of continuous dynamic berth allocation to containerships in a tidal seaport. In some container ports, low water depth in coastal area causes many restrictions on providing vessel's services. Therefore, berth allocation planning for relatively large vessels with high draft is subject to tidal conditions when the vessels are in the access channel as from anchorage area to the quay. Tidal conditions sometimes have a significant effect on possibility of entrance and departure of these ships to or from ports. Shahid Rajaee Port Complex, Iran's largest container seaport and the case study of this research, located at northern coast of Persian Gulf and has low water depth in its area. Historical data of seaside operations in this port is applied to the proposed model. This model also takes into account the variations of water depth in different berths. Simultaneous programming for two or more container terminals and exertion of priority and precedency coefficients based on vessel size and voyage type altogether are other attributes of this model. Here, genetic algorithm in combination with pattern search algorithm was used for solving the problem. Computational experiments have indicated that the proposed heuristic is relatively effective just for small size instances.

This study assesses the kinetics of hydration of Pulverised Fuel Ash and Metakaolin cement pastes and compares how the rate of reaction affects the pore-characteristics and resistance to ionic ingress. The degrees of hydration for the different mixtures were evaluated, both as a function of the calcium hydroxide content and with respect to the chemically combined water contents. The reaction rates have been evaluated using a mathematical model (Jander model), which describes the hydration kinetics of the two materials. The results show that the reaction rate for specimens incorporating Metakaolin is several folds higher than those incorporating Pulverised fuel ash. The faster rate of reaction of the pozzolanic blends results in a faster rate of filling the pore spaces with hydration products, smaller pore volumes and reduced chloride ion diffusivity. The results from this investigation will provide engineers with a much needed uunderstanding of the kinetics of hydration and setting characteristics of these types of cement systems and help in gaining an appreciation of the early structural development, ease of placement and subsequent evolution of properties.

The paper presents a hybrid-enhanced algorithm based on CSS for discrete problems whit the focus on traveling salesman problem. The CSS algorithm based on some principles from physics and mechanics, utilize the governing Coulomb law from electrostatics and Newtonian laws of mechanics. However, the CSS is more suitable for continuous problems compared with discrete problems. In this paper, we have tried to resolve this defect of CSS algorithm with the help of local search methods and nearest neighbor for discrete problems whit the focus on traveling salesman problem (TSP). To prove the efficiency of the proposed algorithm, results compared with the results of benchmark problems. Then, the proposed algorithm is used to solve the TSP, using as a method for solving the single row facility layout problem (SRFLP). To prove the efficiency, the results are compared with the results of benchmark problems reported in the recent literatures.

Short-term traffic flow forecasting plays a significant role in the Intelligent Transportation Systems (ITS), especially for the traffic signal control and the transportation planning research. Two mainly problems restrict the forecasting of urban freeway traffic parameters. One is the freeway traffic changes non-regularly under the heterogeneous traffic conditions, and the other is the successful predictability decreases sharply in multiple-steps-ahead prediction. In this paper, we present a novel pattern-based short-term traffic forecasting approach based on the integration of multi-phase traffic flow theory and time series analysis methods. For the purpose of prediction, the historical traffic data are classified by the dynamic flow-density relation into three traffic patterns (free flow, synchronized and congested pattern), and then different predict models are built respectively according to the classified traffic patterns. With the current traffic data, the future traffic state can be online predicted by means of pattern matching to identify traffic patterns. Finally, a comparative study in a section of the Third-Loop Freeway, LIULIQIAO, Beijing city, shows that the proposed approach represents more accurately the anticipated traffic flow when compared to the classical time series models that without integration with the traffic flow theory.