Showing papers in "International Journal of Engineering and Applied Sciences in 2013"

Optimum configuration of fuel cell-b pv/wind hybrid system using a hybrid metaheuristic technique

Abstract: Because of their low impact on environment, PV/wind hybrid systems which use fuel cells (FCs) as the energy storage device are one of the most promising renewable energy sources. In such systems, optimum configuration (sizing) plays an important role for decreasing the system cost. In this paper, PV/wind/FC system is modeled and a hybrid metaheuristic technique based on chaotic search (CS), harmony search (HS) and simulated annealing (SA) is employed to find the optimum configuration. Optimum configuration is found for PV/FC, wind/FC, and PV/wind/FC systems and the results are compared.

Downsizing of a naturally aspirated engine to turbocharged gasoline direct injection variable valve timing engine

Abstract: The need to reduce CO2 emissions and fuel consumption has become the biggest aim of Original Equipment Manufacturers (OEM’s) over the past decade. Different strategies are being sought after to comply with stringent emission regulations being enforced on the global automotive market. Engine downsizing is proving to be the most cost-effective method of reducing emissions and fuel consumption. This paper presents 1-D CFD simulation using Ricardo WAVE of 30% downsizing on a 2.0 litre naturally aspirated spark ignition engine to a 1.4 litre turbocharged gasoline direct injection variable valve timing engine. Performance improvement has been achieved by using turbocharging and variable valve technology. Turbocharging a spark ignition engine increases the intake temperature and pressure, causing the mixture to detonate. To prevent engine mixture detonation, direct injection has been used, which also allows an increase in the compression ratio. The downsized engine has been optimised for maximum volumetric efficiency, maximum brake mean effective pressure and knock elimination. Valve opening timing, their durations and lifts have been optimised to improve volumetric efficiency. Fuel-air ratio and start of injection timing have also been optimised to improve the maximum brake mean effective pressure. The results indicated 74% improvement in torque, 102% improvement in power and 24% reduction in brake specific fuel consumption (bsfc).

An economic reliability test plan for generalized log- logistic distribution

Abstract: The generalized log-logistic distribution is considered as a probability model for the lifetime of the product. Sampling plans in which items that are put to test, to collect the life of the items in order to decide upon accepting or rejecting a submitted lot, are called reliability test plans. A test plan to determine the termination time of the experiment for a given sample size, producer’s risk and termination number is constructed. The comparison of the present test plan over similar plans exists in the literature is established with respect to time of the experiment. Results are illustrated by an example.

Mixed convection flow micropolar fluid over a vertical plate subject to hall and ion-slip currents

Abstract: This paper analyses the mixed convection flow of an incompressible micropolar fluid along a semi-inSnite vertical plate with uniform heat and mass flux in the presence of transverse magnetic Seld. The governing nonlinear partial differential equations are transformed into a system of coupled nonlinear ordinary differential equations using local similarity transformations and then solved numerically using the Keller-box method. The non-dimensional velocity components, microrotation, temperature and concentration are presented graphically for various values of magnetic parameter, Hall parameter, Ion-slip parameter, Dufour and Soret numbers. In addition, the Nusselt number, the Sherwood number, the skin-friction coefficient, the wall couple stress are shown in a tabular form

Effect of coefficients of regression model on performance prediction curves

Abstract: As bridges age, structural weakening due to heavy traffic and aggressive environmental factors becomes more important. These factors lead to an increase in repair frequency and decrease in load carrying capacity. Structural weakening can decrease the lifetime period and prevent the serviceability of bridges. In order to avoid the disadvantages of deterioration, the lifetime performance prediction of a bridge system should be correctly predicted. Using the lifetime performance prediction, the remaining service life of the bridge system could be predicted. In addition, the best maintenance and repair strategies kept the system in safe can be obtained. In this study, a regression model is investigated as performance prediction model. Moreover, effects of the changes of the coefficients of regression model on the performance curve are examined

Vibration control of a nonlinear dynamical system with time varying stiffness subjected to multi external forces

Abstract: The dynamical system with time varying stiffness subjected to multi excitation forces studied. The system is written as two degree of freedom consists of the main system and absorber. The multiple time scale perturbation method is applied to get the approximate solution up to the third approximation. The stability of the system at the simultaneous primary resonance is investigated using both frequency response equations and phase-plane methods. The effects of different parameters are studied numerically

Application of deterministic seismic hazard analysis on the area of 1970 gediz earthquake

Abstract: Deterministic seismic hazard analysis is used to evaluate the effects of potential earthquakes. By using this approach, approximate peak ground acceleration (PGA) values can be estimated for the area of interest. In this research, the area which was severely affected by the 1970 Gediz earthquake has been studied to assess the PGA distribution. Detailed geological characteristics and scientific parameters (unit distribution, fault locations and attenuation relationships) are the main input for the results. Four main fault zones are used for modeling and according to marks, peak earthquake magnitude generated from the fault zones and type of geological units are the main interest for the location of the settlements

Micropiles applications for seismic retrofitting of historical bridges

Abstract: Masonry bridges are regarded as the oldest examples of engineered structures in the world. Therefore, the preservation of these structures is getting a great deal of attention in the structural engineering community. And as such, restoration, strengthening and reinforcement of historical masonry bridges have become a challenge for civil engineers. In general, and to most extent, engineers have relied on several traditional retrofitting techniques that could be implemented for historic bridges. However, traditional retrofitting techniques have been inadequate for improving seismic behavior and resistance of these structures. With current advancement in materials and construction techniques, new technologies that can be appealing to historical bridges are emerging. Among these techniques include underpinning using micropiles with the technique called “micropiling”. Today, micropiles are used for the structural and seismic retrofitting of bridges, mosques, churches and many other ancient cultural heritage and modern structures. This study mainly focuses on historical masonry bridges; and it consists of three major parts. The first part introduces seismic retrofitting using micropiles for historical bridges. The second part discusses advantages and disadvantages of micropiling compared to other underpinning methods, in terms of seismic performance. Finally, the third part presents examples of applications in different parts of the world

An indoor to outdoor propagation model at gsm 900 gsm1800 and cdma2100

Abstract: An empirical indoor to outdoor propagation model has been improved based on empirical techniques. Improved model includes building structures such as number of walls, position of windows and the affect of frequency. Proposed model is valid for GSM 900, GSM 1800 and CDMA 2100. Theory and measurements are in tracking each other at CDMA2100 and GSM frequencies by at most 6dB deviation. Generated model can easily be used for outdoor coverage predictions and interference capability based on indoor antennas, especially at CDMA

Strength and durability studies on sodium nitrite inhibitor in ordinary and high performance concrete

Abstract: Deterioration of concrete occurs due to physical actions, chemical reactions and electro chemical reactions at steel / concrete interface causing reinforcement corrosion. Among these, reinforcement corrosion is one of the most important causes of deterioration. Reinforcement corrosion induced by chlorides is one of the most frequent causes of corrosion of steel and 40 percent of steel corrodes due to chloride attack. To delay the corrosion process many techniques such as increasing the concrete cover over rebar, reducing water cement ratio, using denser concrete, coating steel with epoxy, use of corrosion inhibitor are available. In the present investigation the effect of sodium nitrite based corrosion inhibitor in concrete is studied. This research involves the comparative study of mechanical properties and durability properties of conventional concrete and high performance concrete in the case of without and with inhibitor. Corrosion studies such as AC impedance, Potential measurement, Linear Polarization Resistance (LPR), Custom sweep and half-cell potential are evaluated using standard concrete test specimens with different dosages of corrosion inhibitor

Stregth of lightweight sintered pulverized fuel ash aggregate concrete with hybrid fibres

Abstract: Worldwide commercial demand of lightweight strong aggregate has increased because of its less self-weight than normal weight aggregate, for also structural applications. Lightweight strong aggregates are available naturally in limited quantity. Synthetic lightweight aggregate can be produced from fly ash. Fly ash is a byproduct while burning coal for electricity, since other sources for electricity, hydropower and nuclear power are limited in resources. Fly ash is pollutant. Hence, its disposal is of increasing concern all over the world. Synthetic lightweight aggregate produced from fly ash is a viable source of structural aggregate material and it will be a solution for these environmental challenges. In this study, artificial lightweight aggregates made from pulverized fuel ash are used instead of granite aggregates in concrete along with steel fibres, polyester fibres and results are presented here. The compressive strength of M20 lightweight aggregate concrete (LWAC) is around 27.75N/mm2. With 0.75 percent steel fibre (LS75P0), it is 35.30 N/mm2and with 0.75 percent steel fibre and 0.3 percent polyester fibre (LS75P3), it is 40.60 N/mm2. On adding steel fibre and polyester fibre to LWAC, the compressive strength of concrete increases by 31.20 percent. The findings of this study include the respective Youngs Modulus

Flexural behaviour of low calcium flash based geopolymer concrete beams

Abstract: The ecosystem is polluted by the emission of green house gas CO2 due to the production of ordinary Portland cement (OPC). An alternate material is substituted with low calcium i.e. Fly ash. Fly ash which is a by-product of coal industry is introduced to replace OPC in the concrete. Fly ash is rich in silicate gel with alkaline solution, to produce a good concrete. Increase in fly ash fitness increases the compressive strength and reduces the porosity. This study is presented on the flexural behaviour of geopolymer concrete (GPC) beams and control cement concrete beams. The beams are cast over an effective span of 3000mm and tested up to failure under static loads. The load displacement response of the geopolymer concrete beams and control beams are obtained to compare with the theoretical results. The result implies that there is an increase in flexural strength, service load, and peak load of geopolymer concrete beams

Structural damage detection for beams subject to moving load using pso algorithms

Abstract: In this work, damage detection (DD) method for beam structures subject to moving load is proposed DD is formulated as an optimization problem and solved for crack locations and depths using three versions of the particle swarm optimization (PSO) It was observed that PSO with constriction factor is superior in the sense of convergence speed and robustness Also, it was experienced that small cracks with depth ratio of 015 can be identified by the present method in spite of 3% noise interference The proposed method is demonstrated to be better than wavelet transform method at higher moving load speeds

Comparison of free vibration and buckling behaviour of cross-ply laminated plates with isotropic and orthotropic plates

Abstract: In the present study Navier method with generalized shear deformation theory for exponential model which proposed by Aydogdu [31] is used to determine the natural frequencies and critical buckling loads of elastic plates. According to the model the transverse shear strains through the thickness direction of the plate are distributed exponential and the theory accounts the rotary inertia. The convergence and comparison studies demonstrate the accuracy and correctness of the present study. The results are obtained for comparing the antisymmetric and symmetric cross-ply laminated plates with isotropic and orthotropic plates for simply supported boundary condition. The material anisotropy, plate geometry (side-side, side-thickness), variation of higher frequencies, and variation of vibration and axial buckling mode shapes are compared

Determine the forces in the muscles of the leg and foot while moving help modeling and testing

Abstract: In this paper, a four-segment musculoskeletal model of the floor and legs is created in AnyBody in which are considered all the muscles and ligaments of the leg and foot. To obtain input this dynamic problem (ground reaction force and path components in the foot during walking) on subjects with normal foot motion analysis and force plate testing has been done. To solve the model and determine the muscle forces is used of the two criteria min-max optimization and fifth order polynomial. For validation, Electromyography testing has been done on the subject. The review results be determined that the min-max optimization criteria than fifth order polynomial optimization criteria estimates closer approximation to the actual muscle activity estimates. Modeling with both criteria min-max and fifth order polynomial, in the anterior tibia muscle activation patterns are weaker than other