فصلنامه مدل سازی در مهندسی
پیاپی 16 (بهار 1388)

Strengthening reinforced concrete framed structures with steel bracings is now a common versatile method in construction industry. Although the method is fairly known to practitioners, but research activities are ste e l in the primary stages. In this paper, the behavior of reinforced concrete frames strengthened with several types of ste e l bracings is investigated. The results indicate that upgrading is most efficient when the span to depth ratio of the original frames is greater than 1.5. Therefore the lateral resistance increases up to three times. It is also found out that the chevron and cross bracings are most effective in upgrading the lateral stiffness of the reinforced concrete moment frames.

The importance of short term load forecasting has been increasing lately. Artificial Neural Network (ANN) Method is applied to forecast the short term load forecasting for a large power system. A nonlinear load model is proposed and several structures of ANN for short term load forecasting are tested. Inputs to the ANN are past loads and the output of the ANN is the load forecast for a given day. More autonomous load predictors are needed in the new competitive scenario.This paper describes two strategies for embedding the discrete wavelet transform into neural network based short term load forecasting. Its main goal is to develop more robust load forecasters.

Increase of design complexity of assembled circuits, and on the other hand necessity to separation the activity of computational and communicational parts in today chips, drives design way to terminals base on network on chips.As technology scales, fault tolerance is becoming a key concern in on-chip communication.Consequently, this work examines fault tolerant communication algorithms for use in the NoC domain, and compares them in terms of the functional parameters. Then introduces a algorithm with purpose of encounter permanent and transient faults with appropriate functional levels. In this manner that against of permanent faults that exist structural in network on chip, packet has a expectation ability and finally return source to find another path and information bits are protected by a cyclic redundancy code (CRC) and Switch-to-Switch Error Control Policies (link level), against of transient faults. with appearance of fault, because of existence several sorts of the same packet in network, it will be discarded. R eceiver doesn’t need to request of retransmission because it will receive redundant of packet from the same or another path.

The purpose of this article was focused on a comprehensive computational approach to detect a malignant tumor by considering the temperature distribution on the skin surface. An unsteady three dimensional bio-heat transfer equation were solved numerically. Parametric studies on the influences of blood perfusion, metabolic heat generation, size of tumor and convective heat transfer coefficient on the skin thermal expression of tumor and especially maximum skin temperature were performed. It was found that convection coefficient has significant effect on thermal history of skin. The numerical results were compared with existing experimental data and a good qualitative agreement was seen.

Generally, gel polymers are an appropriate method for increasing the rate of production of the oil reservoirs. To analyses the effects of gels on the oil reservoirs we will not only need to perform several experiments for determining of gel properties, also require to examine gel motion through the porous media by making use of a simulator software. In this paper a two dimensional, two phase (oil & water) permeability modification modeling developed by including a gelation model into a fluid flow equations. The partial differential equation of motion if the flow & gelation model in porous media one first discretized and then transferred into the non linear-couple algebra equations. The equations will be solved numerically. The results of simulation show the permeability modification in porous media for 5 years. This model is an appropriate mathematical model for examination of both permeability reduction and water production rate effects in porous media; also the permeability modification due to the gel injection in a porous media will be analyzed by using the Civan's power low. Ultimately, the results obtained are compared with experimental data for one of the Iranian Asmari reservoir, which shows a desirable accuracy of the presented mathematical model.

In this paper mechanism of growth and collapse of vapor films formed on the surface of hot spheres during interaction with water is investigated. Mathematical modeling of problem is done by taking into account nonequilibrium effects on interface surface of liquid and vapor. Variation of radius of vapor film, liquid-vapor interface temperature and vapor pressure inside film are obtained. results of numerical solution is compared with experimental data and consistency between numerical and experimental results approves the suggested model..

The structures are often design for strength lower than that required for elastic behavior. However, the evaluation of the structural response under intensity earthquakes shows that they resist well due to material nonlinearity and ductile plastic deformations.These structures dissipate the earthquake induced energy by undergoing large displacements. One of the important design criteria is to prevent pounding of two neighborhood buildings. The ratio of inelastic to elastic displacement are calculated and compared with those suggested by Iranian Standard No-2800. The results show that those recommended by Seismic Iranian Code are suitable for high rise buildings, however for low rise structures it is necessary to be revised.