Showing papers in "alexandria engineering journal in 2014"
TL;DR: In this article, an experimental investigation was conducted in a single cylinder constant speed diesel engine to establish the effects of Carbon Nanotubes (CNT) with the Jatropha Methyl Esters (JME) emulsion fuel.
Abstract: An experimental investigation was conducted in a single cylinder constant speed diesel engine to establish the effects of Carbon Nanotubes (CNT) with the Jatropha Methyl Esters (JME) emulsion fuel. The JME was produced from the Jatropha oil by transesterification process, and subsequently the JME emulsion fuel was prepared in the proportion of 93% of JME, 5% of water and 2% of surfactants (by volume) with a hydrophilic–lipophilic balance of 10. The Carbon Nanotubes are blended with the JME emulsion fuel in the various dosages systematically. The whole investigation was conducted in the diesel engine using the following fuels: neat JME, neat JME emulsion fuel and CNT blended JME emulsion fuels accordingly. The experimental results revealed an appreciable enhancement in the brake thermal efficiency for the CNT blended JME emulsion fuels compared to that of neat JME and neat JME emulsion fuel. At the full load, the brake thermal efficiency for the JME fuel observed was 24.80%, whereas it was 26.34% and 28.45% for the JME2S5W and JME2S5W100CNT fuels respectively. Further, due to the combined effects of micro-explosion and secondary atomization phenomena associated with the CNT blended JME emulsion fuels, the level of harmful pollutants in the exhaust gases (such as NOx and smoke) was drastically reduced when compared to that of neat JME. At the full load, the magnitude of NOx and smoke opacity for the neat JME was 1282 ppm and 69%, whereas it was 910 ppm and 49% for the JME2S5W100CNT fuel respectively.
279 citations
TL;DR: In this paper, in-depth research and comparative study of blends of biodiesel made from WCO and diesel is carried out to bring out the benefits of its extensive usage in CI engines.
Abstract: Biodiesel has been identified as a potential alternative fuel for CI engines because use of biodiesel can reduce petroleum diesel consumption as well as engine out emissions Out of many biodiesel derived from various resources, biodiesel from Waste Cooking Oil (WCO) can be prepared economically using usual transesterification process In the present study, in-depth research and comparative study of blends of biodiesel made from WCO and diesel is carried out to bring out the benefits of its extensive usage in CI engines The experimental results of the study reveal that the WCO biodiesel has similar characteristics to that of diesel The brake thermal efficiency, carbon monoxide, unburned hydrocarbon and smoke opacity are observed to be lower in the case of WCO biodiesel blends than diesel On the other hand specific energy consumption and oxides of nitrogen of WCO biodiesel blends are found to be higher than diesel In addition combustion characteristics of all biodiesel blends showed similar trends when compared to that of conventional diesel
172 citations
TL;DR: In this paper, a comprehensive experimental program regarding the use of recycled aggregates produced from demolition of brick buildings is presented, where the brick wastes were crushed, sorted and classified into coarse and fine aggregates as well as powder (CBP).
Abstract: A comprehensive experimental program regarding the use of recycled aggregates produced from demolition of brick buildings is presented. The brick wastes were crushed, sorted and classified into coarse and fine aggregates as well as powder (CBP). The first phase of the research focuses on the effect of incorporating recycled aggregates on physico-mechanical properties of paste, mortar and concrete. Non-traditional tests including X-ray diffraction (XRD), thermo-gravimetric analysis (TGA) and micro-structural analysis (MSA) were performed. The second phase of the program explores the effect of using recycled aggregates on properties of concrete masonry units. A total of 44 mixtures were utilized throughout the program. Results show cement paste when modified with 25% CBP achieves smaller pore size and lower weight loss under high temperature than reference paste. Furthermore, the use of recycled aggregates reduces the overall unit weight of concrete masonry units. Actually, modified concrete masonry units incorporating recycled aggregates achieve lower unit weight, higher thermal resistance and absorption rate than reference units. Although considerable strength reduction is noticeable by substitution, compressive strength levels meet the Egyptian specifications limitations. Critical replacement ratios are suggested to produce load bearing-concrete masonry units. Based on experimental evidences, it can be stated that the use of recycled aggregate and dust made of clay bricks is promising in many applications where the thermal resistance, cost and environmental aspects are imperative.
155 citations
TL;DR: In this paper, an Artificial Neural Network (ANN) was used to forecast the River Nile flow at Dongola Station in Sudan using an ANN as a modeling tool and validated the accuracy of the model against actual flow.
Abstract: Heavy seasonal rains cause the River Nile in Sudan to overflow and flood the surroundings areas. The floods destroy houses, crops, roads, and basic infrastructure, resulting in the displacement of people. This study aimed to forecast the River Nile flow at Dongola Station in Sudan using an Artificial Neural Network (ANN) as a modeling tool and validated the accuracy of the model against actual flow. The ANN model was formulated to simulate flows at a certain location in the river reach, based on flow at upstream locations. Different procedures were applied to predict flooding by the ANN. Readings from stations along the Blue Nile, White Nile, Main Nile, and River Atbara between 1965 and 2003 were used to predict the likelihood of flooding at Dongola Station. The analysis indicated that the ANN provides a reliable means of detecting the flood hazard in the River Nile.
148 citations
TL;DR: In this paper, the authors analyzed the flow of three-dimensional water-based nanofluid over an exponentially stretching sheet, where the transport equations were transformed into nonlinear, coupled similarity equations using 3D exponential type similarity transformations.
Abstract: The aim of the present study is to analyze the flow of three-dimensional water-based nanofluid over an exponentially stretching sheet. The transport equations are transformed into nonlinear, coupled similarity equations using three-dimensional exponential type similarity transformations. These equations are solved numerically to obtain the velocities and temperature in the respective boundary layers. Results are presented to illustrate the effects of various parameters including the temperature exponent, stretching parameter and volume fraction of three different types of nanoparticles, such as copper (Cu), alumina (Al2O3) and titanium dioxide (TiO2) with water as a base fluid.
144 citations
TL;DR: In this paper, six different techniques were applied on the same textile wastewater to evaluate the most effective in terms of treatment efficiency and the three most important textile wastewater quality parameters of chemical oxygen demand (COD), total suspended solids (TSS), and color were made the basis of the comparison of different treatment techniques.
Abstract: Toxic organic dye removal from the textile wastewater is a serious concern. It is difficult to choose a single or a combination of treatment techniques between various available options; each with certain advantages and drawbacks. Six different techniques were applied on the same textile wastewater to evaluate the most effective in terms of treatment efficiency. The three most important textile wastewater quality parameters of chemical oxygen demand (COD), total suspended solids (TSS) and color were made the basis of the comparison of different treatment techniques. Other critical parameters such as treatment time, ease of operation and chemical cost employed were also considered. No single biological or physico-chemical treatment technique was found capable of removing up to 80% of the influent COD, TSS and color simultaneously from the textile wastewater. The conventional activated sludge (CAS) treatment followed by effluent polishing with the sand filtration (SF) and activated carbon adsorption columns was proved to be the most promising with COD, TSS and color removal efficiencies of 81.6%, 88.5% and 94.5% respectively. Moreover this combination of techniques enjoys lower chemical cost, medium operation time and fewer difficulties in the process control. Hence, the combination is recommended for the treatment of the textile effluents.
130 citations
TL;DR: In this article, a differential evolution (DE) algorithm based Proportional-Integral (PI) controller and PID controller for automatic generation control (AGC) of an interconnected power system is presented.
Abstract: This paper presents the design and performance analysis of Differential Evolution (DE) algorithm based Proportional–Integral (PI) and Proportional–Integral–Derivative (PID) controllers for Automatic Generation Control (AGC) of an interconnected power system. Initially, a two area thermal system with governor dead-band nonlinearity is considered for the design and analysis purpose. In the proposed approach, the design problem is formulated as an optimization problem control and DE is employed to search for optimal controller parameters. Three different objective functions are used for the design purpose. The superiority of the proposed approach has been shown by comparing the results with a recently published Craziness based Particle Swarm Optimization (CPSO) technique for the same interconnected power system. It is noticed that, the dynamic performance of DE optimized PI controller is better than CPSO optimized PI controllers. Additionally, controller parameters are tuned at different loading conditions so that an adaptive gain scheduling control strategy can be employed. The study is further extended to a more realistic network of two-area six unit system with different power generating units such as thermal, hydro, wind and diesel generating units considering boiler dynamics for thermal plants, Generation Rate Constraint (GRC) and Governor Dead Band (GDB) non-linearity.
119 citations
TL;DR: In this paper, the effect of various filler types on the fresh and hardened properties of self-compacting concrete (SCC) and Flow-able concrete was evaluated and the results showed that filler type and content have significant effect on fresh concrete properties where non-pozzolanic fillers improve segregation and bleeding resistance.
Abstract: The objective of this study is to evaluate the effect of various filler types on the fresh and hardened properties of self-compacting concrete (SCC) and Flow-able concrete. For this purpose, two groups of fillers were selected. The first group was pozzolanic fillers (silica fume and metakaolin) while the second group was non-pozzolanic fillers (limestone powder, granite dust and marble dust). Cement contents of 400 kg/m 3 and 500 kg/m 3 were considered while the used filler material was 7.5%, 10% and 15%. Slump and slump flow, T50, sieve stability and bleeding tests were performed on fresh concrete. The studied hardened properties included unit weight, voids ratio, porosity, and water absorption and cube compressive strength. In addition, thermo-gravimetric analysis, X-ray diffraction analysis and scanning electronic microscope were performed. The test results showed that filler type and content have significant effect on fresh concrete properties where non-pozzolanic fillers improve segregation and bleeding resistance. Generally, filler type and content have significant effect on unit weight, water absorption and voids ratio. In addition, non-pozzolanic fillers have insignificant negative effect on concrete compressive strength. Finally, there was a good correlation between fresh concrete properties and hardened concrete properties for SCC and Flow-able concrete.
107 citations
TL;DR: In this paper, the exact solutions for fundamental flows namely Couette, Poiseuille and generalized Couette flows of an incompressible couple stress fluid between parallel plates are obtained using slip boundary conditions.
Abstract: In the present article, the exact solutions for fundamental flows namely Couette, Poiseuille and generalized Couette flows of an incompressible couple stress fluid between parallel plates are obtained using slip boundary conditions. The effect of various parameters on velocity for each problem is discussed. It is found that, for each of the problems, the solution in the limiting case as couple stresses approaches to zero is similar to that of classical viscous Newtonian fluid. The results indicate that, the presence of couple stresses decreases the velocity of the fluid.
92 citations
TL;DR: In this paper, the steady boundary layer flow and heat transfer of a hyperbolic tangent fluid flowing over a vertical exponentially stretching cylinder in its axial direction was studied, and a system of coupled nonlinear ordinary differential equations was obtained with the help of Runge-Kutta-Fehlberg method.
Abstract: The present problem is the steady boundary layer flow and heat transfer of a hyperbolic tangent fluid flowing over a vertical exponentially stretching cylinder in its axial direction. After applying usual boundary layer with a suitable similarity transformation to the given partial differential equations and the boundary conditions, a system of coupled nonlinear ordinary differential equations is obtained. This system of ordinary differential equations subject to the boundary conditions is solved with the help of Runge–Kutta–Fehlberg method. The effects of the involved parameters such as Reynolds numbers, Prandtl numbers, Weissenberg numbers and the natural convection parameter are presented through the graphs. The associated physical properties on the flow and heat transfer characteristics that is the skin friction coefficient and Nusselt numbers are presented for different parameters.
85 citations
TL;DR: In this article, the authors studied MHD peristaltic flow of a Carreau nanofluid in an asymmetric channel, where the flow development is carried out in a wave frame of reference moving with velocity of the wave c 1.
Abstract: In this article, we studied MHD peristaltic flow of a Carreau nanofluid in an asymmetric channel. The flow development is carried out in a wave frame of reference moving with velocity of the wave c 1 . The governing nonlinear partial differential equations are transformed into a system of coupled nonlinear ordinary differential equations using similarity transformations and then tackled numerically using the fourth and fifth order Runge–Kutta–Fehlberg. Numerical results are obtained for dimensionless velocity, stream function, pressure rise, temperature and nanoparticle volume fraction. It is found that the pressure rise increases with increase in Hartmann Number and thermophoresis parameter.
TL;DR: In this paper, the authors investigated the possibility of using low-cost agriculture waste as doum-palm seed coat for the removal of nickel ions from aqueous solutions.
Abstract: The present study investigates the possibility of using low cost agriculture waste as doum-palm seed coat for the removal of nickel ions from aqueous solutions. Two activated carbons had been prepared from raw doum-palm seed coat (DACI and DACII); as well, the raw material was used as an adsorbent (RD). Batch adsorption experiments were performed as a function of pH of solution, initial nickel ions concentration, dose of adsorbent and contact time. Adsorption data were modeled using Langmuir, Freundlich, Temkin and D–R Models. Different error analysis conforms that the isotherm data followed Freundlich models for all adsorbents. Adsorption kinetic data were tested using pseudo-first order, pseudo-second order and Elovich model. Adsorption mechanism was investigated using the intra-particle diffusion model. Diffusion coefficients were calculated using the film and intraparticle diffusion models. Kinetic studies showed that the adsorption of Ni2+ ions onto RD, DACI and DACII followed pseudo-second order kinetic model, and indicates that the intra-particle diffusion controls the rate of adsorption but it is not the rate limiting step.
TL;DR: In this article, an experimental investigation was carried out under different loading conditions in a three cylinder diesel engine with its piston crown coated with Yttria Stabilized Zirconia (YSZ) to understand the influence of thermal barrier coating (TBC) on performance and emission characteristics in comparison with baseline engine characteristics.
Abstract: Experimental investigation is carried out under different loading conditions in a three cylinder diesel engine with its piston crown coated with Yttria Stabilized Zirconia (YSZ) to understand the influence of the thermal barrier coating (TBC) on performance and emission characteristics in comparison with baseline engine characteristics. YSZ is chosen as the candidate material for coating the piston crown because of its desirable physical properties such as high coefficient of thermal expansion, low thermal conductivity, high Poisson’s ratio, and stable phase structure at higher temperature conditions. For the measurement of emission characteristics, ISO 8178-4 “C1” 8 Mode testing cycle procedure is followed. Experimental results revealed that the heat loss to the cooling water is reduced up to 5–10% and the thermal efficiency is increased by 3–5% with reduction of brake specific fuel consumption by up to 28.29%. Experimental results also revealed that Hydro carbon (HC) emission is reduced up to 35.17%, carbon monoxide (CO) by up to 2.72% and Carbon di-oxide (CO 2 ) emission is increased by up to 5.6%.
TL;DR: A taxonomy of requirements defects and the causes of their occurrences is presented to reach a comprehensive understanding of both the sources of the problem and the solutions of possible defects and defect detection techniques.
Abstract: This research is concerned with detecting defects in software requirements specification. Motivated by both the problem of producing reliable requirements and the limitations of existing taxonomies to provide a satisfactory level of information about defects in the requirements phase, we focus on providing a better tool for requirements analysts. Only few attempts have been made to classify defects and defect detection techniques. Scattered knowledge about defects and defect detection techniques needs compilation and re-evaluation in order to enhance the ability to discover defects in the requirements phase. Toward this end, this work presents a taxonomy of requirements defects and the causes of their occurrences. The purpose is to reach a comprehensive understanding of both the sources of the problem and the solutions of possible defects and defect detection techniques. The taxonomy’s design is based on the analysis of each defect and its sources. In addition, this paper proposes a combined-reading technique for defects in requirements. The proposed technique avoids the shortcomings of other reading techniques. The result of applying the recommendations of this work specifically improves the quality of the requirements specification and generally software quality.
TL;DR: In this paper, a sequential batch reactor (SBR) was employed for the treatment of textile dye wastewater and the performance of four white rot fungi (WRF) viz. Coriolus versicolor, Pleurotus floridanus, Ganoderma lucidum and Trametes pubescens was evaluated in pure and mixed combinations in terms of decolorization.
Abstract: In this work, sequential batch reactor (SBR) was employed for the treatment of textile dye wastewater. The performance of four white rot fungi (WRF) viz. Coriolus versicolor, Pleurotus floridanus, Ganoderma lucidum and Trametes pubescens was evaluated in pure and mixed combinations in terms of decolorization. From the results it was found that the combination of Pleurotus floridanus, Ganoderma lucidum and Trametes pubescens was best and they were used in the SBR. The process parameters like air flow rate, sludge retention time (SRT) and cycle period were optimized using response surface methodology (RSM). At these optimized conditions, treatment of textile dye wastewater was carried out at various initial dye wastewater concentration and hydraulic retention time. The performance of SBR was analyzed in terms of decolorization, COD reduction and sludge volume index (SVI). From the results it was found that a maximum decolorization and COD reduction of 71.3% and 79.4%, respectively, was achieved in the SBR at an organic loading rate of 0.165 KgCOD/m3 d. The sludge volume index (SVI) was found to be low in the range of 90–103 mL/g. The kinetic study was carried out using a first order based model and the degradation follows the first order system.
TL;DR: In this paper, the authors investigated the unsteady boundary layer flow of a nanofluid over a heated stretching sheet with thermal radiation and found that the heat transfer rate at the surface increases in the presence of Brownian motion but reverse effect occurs for thermophoresis.
Abstract: This paper investigates the unsteady boundary layer flow of a nanofluid over a heated stretching sheet with thermal radiation. The transport model employed includes the effects of Brownian motion and thermophoresis. The unsteadiness in the flow field is caused by the time-dependence of the stretching velocity, free stream velocity and the surface temperature. The unsteady boundary layer equations are transformed to a system of non-linear ordinary differential equations and solved numerically using a shooting method together with Runge–Kutta–Fehlberg scheme. The clear liquid results from this study are in agreement with the results reported in the literature. It is found that the heat transfer rate at the surface increases in the presence of Brownian motion but reverse effect occurs for thermophoresis.
TL;DR: In this article, the removal of cobalt from wastewater using Saudi activated clay (bentonite) was investigated under various operating variables such as contact time, solution pH, clay dosage and initial metal concentration.
Abstract: In this study, removal of cobalt from wastewater using Saudi activated clay (bentonite) was investigated. The removal characteristics were investigated under various operating variables such as contact time, solution pH, clay dosage and initial metal concentration. It was found that adsorption of cobalt ions on Saudi activated bentonite was relatively fast and the equilibrium was reached after 30 min. Adsorption was also dependent on solution pH where cobalt removal percentage gradually increased with increasing solution pH up to 99% at pH 8. Moreover, about 100% cobalt removal was observed when solution pH was increased to more than 8. The results showed that increasing the initial cobalt concentration decreased cobalt removal percentage due to saturation of clay with cobalt ions. The adsorption isotherm data were well fitted with both the linearized Langmuir and Freundlich models. Furthermore, the value of the mean free energy determined with the D–R equation showed that adsorption process is chemisorptions. Cobalt adsorption into Saudi activated bentonite was well represented by the pseudo-second-order kinetic model.
TL;DR: In this paper, the problem of how to optimally determine the locations to install capacitors and the sizes of capacitors to be installed in the buses of radial distribution systems is addressed.
Abstract: The use of capacitors in power systems has many well-known benefits that include improvement of the system power factor, improvement of the system voltage profile, increasing the maximum flow through cables and transformers and reduction of losses due to the compensation of the reactive component of power flow. By decreasing the flow through cables, the systems’ loads can be increased without adding any new cables or overloading the existing cables. These benefits depend greatly on how capacitors are placed in the system. In this paper, the problem of how to optimally determine the locations to install capacitors and the sizes of capacitors to be installed in the buses of radial distribution systems is addressed. The proposed methodology uses loss sensitivity factors to identify the buses requiring compensation and then a discrete particle swarm optimization algorithm (PSO) is used to determine the sizes of the capacitors to be installed. The proposed algorithm deals directly with discrete nature of the design variables. The results obtained are superior to those reported in Prakash and Sydulu (2007).
TL;DR: In this paper, an interval type-2 fuzzy logic controller (IT2-FLC) is proposed to model and minimize the numerical and linguistic uncertainties associated with the inputs and outputs of a fuzzy logic system (FLS).
Abstract: The interval type-2 fuzzy logic controller (IT2-FLC) is able to model and minimize the numerical and linguistic uncertainties associated with the inputs and outputs of a fuzzy logic system (FLS). This paper proposes an interval type-2 fuzzy PD (IT2F-PD) controller for nonlinear inverted pendulum. The proposed controller uses the Mamdani interval type-2 fuzzy rule based, interval type-2 fuzzy sets (IT2-FSs) with triangular membership function, and the Wu–Mendel uncertainty bound method to approximate the type-reduced set. The proposed controller is able to minimize the effect of the structure uncertainties and the external disturbances for the inverted pendulum. The results of the proposed controller are compared with the type-1 fuzzy PD (T1F-PD) controller in order to investigate the effectiveness and the robustness of the proposed controller. The simulation results show that the performance of the proposed controller is significantly improved compared with the T1F-PD controller. Also, the results show good performance over a wide range of the structure uncertainties and the effect of the external disturbances.
TL;DR: In this paper, the authors examined the adsorption capacity of raw luffa fibers for different types of oil and water pickup and revealed that the efficiency of fibers to remove crude oil from sea water was related to the surface properties of the fibers, concentration of the oil, amount of the fiber, as well as the temperature of the crude oil.
Abstract: Oil spills have a global concern due to its environmental and economical impact. Various commercial systems have been developed to control these spills, including the use of fibers as sorbents. However, plant biomass is renewable resource that can be converted into useful materials and energy. Luffa, an agricultural waste, was used as a sorbent material. The present study examines the adsorption capacity of raw luffa fibers for different types of oil and water pickup. The investigation revealed that the efficiency of fibers to remove crude oil from sea water was related to the surface properties of the fibers, concentration of the oil, amount of the fibers, as well as the temperature of the crude oil. The results show high sorption efficiency of luffa fibers for different kinds of oil. This sorbent also exhibited a good reusability since the decrease in sorption efficiency did not exceed 50% of the initial value after three sorption cycles.
TL;DR: In this article, a neural network model was used to predict compressive strength, expansion and weight loss due to sulfate attack in concrete and concrete compositions, which can be used easily to predict the compressive-strength loss after any certain age.
Abstract: This work was divided into two phases. Phase one included the validation of neural network to predict mortar and concrete properties due to sulfate attack. These properties were expansion, weight loss, and compressive strength loss. Assessment of concrete compressive strength up to 200 years due to sulfate attack was considered in phase two. The neural network model showed high validity on predicting compressive strength, expansion and weight loss due to sulfate attack. Design charts were constructed to predict concrete compressive strength loss. The inputs of these charts were cement content, water cement ratio, C3A content, and sulfate concentration. These charts can be used easily to predict the compressive strength loss after any certain age and sulfate concentration for different concrete compositions.
TL;DR: Watermelon rind (WR) an agro waste was evaluated as an adsorbent for the removal of Cr 3+ ions from aqueous solution as mentioned in this paper, and the results concluded that watermelon can effectively be used for removing chromium ions from the solution.
Abstract: Watermelon rind (WR) an agro waste was evaluated as an adsorbent for the removal of Cr 3+ ions from aqueous solution. Batch mode adsorption studies were performed by varying parameters such as pH, contact time, adsorbent dose and initial metal ion concentration. Maximum loading capacity of WR was found to be 172.6 mg g −1 for Cr 3+ ions at pH 3. Kinetic studies show that removal of Cr 3+ ions is rapid and follows a pseudosecond order model. Equilibrium data fit better with the Langmuir isotherm than the Freundlich isotherm. Thermodynamic parameters such as ΔG°, ΔH° and ΔS° were derived for the current system. The negative values of ΔG° show that the nature of sorption process is spontaneous. FTIR studies reveal that hydroxyl and carboxyl groups were responsible for uptake of metal ions. Successive desorption of Cr 3+ ions reveals that WR can be an economical sorbent for the removal of heavy metals from aqueous solution. The results conclude that watermelon rind an agro waste can effectively be used for the removal of chromium ions from aqueous solution.
TL;DR: In this article, the effect of the reinforcement distribution on the beam overall capacity has been studied and compared to the Egyptian code guidelines for the analysis of reinforced concrete deep beams with and without web openings.
Abstract: The exact analysis of reinforced concrete deep beams is a complex problem and the presence of web openings aggravates the situation. However, no code provision exists for the analysis of deep beams with web opening. The code implemented strut and tie models are debatable and no unique solution using these models is available. In this study, the finite element method is utilized to study the behavior of reinforced concrete deep beams with and without web openings. Furthermore, the effect of the reinforcement distribution on the beam overall capacity has been studied and compared to the Egyptian code guidelines. The damaged plasticity model has been used for the analysis. Models of simply supported deep beams under 3 and 4-point bending and continuous deep beams with and without web openings have been analyzed. Model verification has shown good agreement to literature experimental work. Results of the parametric analysis have shown that web openings crossing the expected compression struts should be avoided, and the depth of the opening should not exceed 20% of the beam overall depth. The reinforcement distribution should be in the range of 0.1–0.2 beam depth for simply supported deep beams.
TL;DR: In this paper, the problem of unsteady MHD free convection flow of nanofluids via a porous medium bounded by a moving vertical semi-infinite permeable flat plate with constant heat source and con- vective boundary condition in a rotating frame of reference is studied theoretically.
Abstract: The problem of unsteady MHD free convection flow of nanofluids via a porous medium bounded by a moving vertical semi-infinite permeable flat plate with constant heat source and con- vective boundary condition in a rotating frame of reference is studied theoretically. The velocity along the plate i.e. slip velocity is assumed to oscillate in time with constant frequency so that the solutions of the boundary layer are the same oscillatory type. The dimensionless governing equations for this investigation are solved analytically using small perturbation approximation. Two types of nanofluids, namely Cu-water and Al2O3-water are used. The effects of various parameters on the flow and heat transfer characteristics are discussed through graphs and tables. a 2014 Production and hosting by Elsevier B.V. on behalf of Faculty of Engineering, Alexandria University.
TL;DR: In this paper, the behavior and efficiency of reinforced concrete square columns strengthened by steel angles and strips (steel cage) was studied and an analytical model was developed using a simple stress mechanics and strain compatibility to obtain the ultimate loads of the strengthened columns including the effect of the confining stress due to the steel cage and axial forces in the vertical angles.
Abstract: The purpose of this paper is to study the behavior and efficiency of reinforced concrete square columns strengthened by steel angles and strips (steel cage). An experimental program was conducted on ten axially loaded column’s specimens till failure. Size of the steel angles, strip spacing, grout material between column sides and angles, and the connection between the steel cage to the specimen head, were the main studied parameters in this paper. Also, an analytical model was developed using a simple stress mechanics and strain compatibility to obtain the ultimate loads of the strengthened columns including the effect of the confining stress due to the steel cage and axial forces in the vertical angles considering both directly and indirectly connected cases. It was concluded that using this strengthening method is very efficient and a gain in the axial load capacity of the strengthened columns was obtained. This gain was due to the confinement effect of the external steel cage, and the ability of the steel angle to resist an extensive part of the applied axial load. The failure in most of the strengthened specimens was due to the buckling of the steel angle followed by crushing of the original columns.
TL;DR: In this paper, the entropy generation for the steady two-dimensional laminar forced convection flow and heat transfer of an incompressible Jeffrey non-Newtonian fluid over a linearly stretching, impermeable and isothermal sheet is numerically investigated.
Abstract: Entropy generation for the steady two-dimensional laminar forced convection flow and heat transfer of an incompressible Jeffrey non-Newtonian fluid over a linearly stretching, impermeable and isothermal sheet is numerically investigated. The governing differential equations of continuity, momentum and energy are transformed using suitable similarity transformations to two nonlinear coupled ordinary differential equations (ODEs). Then the ODEs are solved by applying the numerical implicit Keller’s box method. The effects of various parameters of the flow and heat transfer including Deborah number, ratio of relaxation to retardation times, Prandtl number, Eckert number, Reynolds number and Brinkman number on dimensionless velocity, temperature and entropy generation number profiles are analyzed. The results reveal that the entropy generation number increases with the increase of Deborah number while the increase of ratio of relaxation to retardation times causes the entropy generation number to reduce. A comparative study of the numerical results with the results from an exact solution for the dimensionless velocity gradient at the sheet surface is also performed. The comparison shows excellent agreement within 0.05% error.
TL;DR: In this article, the removal of cottonseed oil from oil-water emulsion by means of electrocoagulation was investigated in a cylindrical batch reactor, and the effects of operating parameters such as, current density, initial oil concentration, pH and NaCl dosage on the oil removal efficiency have been studied.
Abstract: The removal of cottonseed oil from oil–water emulsion by means of electrocoagulation was investigated in a cylindrical batch reactor. The effects of operating parameters such as, current density, initial oil concentration, pH and NaCl dosage on the oil removal efficiency have been studied. Current density (c.d.) ranged from 0.0009 to 0.02 A/cm 2 , the initial oil concentrations investigated were 200, 300 and 400 ppm, and pH values used were 3, 5, 7, 9 and 11. Emulsion conductivity was changed using different concentrations of NaCl (1.5% and 3.5% and 85 ppm) as an electrolyte, to show its effect on the oil removal. The electrodes were made of steel in the form of horizontal intermeshing vanes, which is considered as a new geometry design. Also, power consumption (KW h/kg oil removed) was calculated to evaluate the economic aspects and their relation with the removal efficiency, in order to figure out the optimum parameters to work with. The oil removal efficiency showed its best values at high current density values, high initial oil concentration with an emulsion of pH around 7. Electrolyte concentration had insignificant effect on the oil removal, but increasing its concentration lowered the power consumption.
TL;DR: In this article, the axisymmetric flow and two-dimensional flow were considered and the Variation of Parameters Method (VPM) was used to solve the Navier-Stokes equations.
Abstract: Squeezing flow of a viscous fluid is considered. Two types of flows are discussed namely, the axisymmetric flow and two dimensional flow. Similarity transform proposed by Wang (1976) [13] has been used to reduce the Navier–Stokes equations to a highly non-linear ordinary differential equation which jointly describes both types of flows. Solution to aforementioned ordinary differential equation is obtained by using Variation of Parameters Method (VPM). VPM is free from the existence of small or large parameters and hence it can be applied to a large variety of problems as compared to the perturbation method applied by Wang (1976) [13]. Comparison among present and already existing solutions is also provided to show the efficiency of VPM. A convergence analysis is also carried out. Effects of different physical parameters on the flow field is discussed and demonstrated graphically with comprehensive discussions and explanations.
TL;DR: In this paper, the generalized (G ′/G )expansion method has been applied to construct general traveling wave solutions of the strain wave equation in microstructured solids.
Abstract: The new approach of generalized ( G ′/ G )-expansion method is significant, powerful and straightforward mathematical tool for finding exact traveling wave solutions of nonlinear evolution equations (NLEEs) arise in the field of engineering, applied mathematics and physics. Dispersive effects due to microstructure of materials combined with nonlinearities give rise to solitary waves. In this article, the new approach of generalized ( G ′/ G )-expansion method has been applied to construct general traveling wave solutions of the strain wave equation in microstructured solids. Abundant exact traveling wave solutions including solitons, kink, periodic and rational solutions have been found. These solutions might play important role in engineering fields.
TL;DR: In this article, a comparison between the single pull-out test and the double pullout test was made to assess the ultimate bond stress of normal and high strength concrete, based on the test results, a proposed concept to assess design ultimate stress was adopted.
Abstract: The aim of this work is to assess the ultimate bond stress of normal and high strength concrete. This study contains two phases. The first phase included the studied bond behavior using two different models. In the first model, single pull-out test (SPOT), the concrete section of specimen was subjected to compressive stresses. In the second model, double pull-out test (DPOT), the concrete section of specimen was subjected to tensile stresses. So this phase of study aimed to make a comparison between the single pull-out test and the double pull-out test. To compare the behavior of these models, different levels of compressive strength were considered through the use of different coarse aggregate types, different W/C ratios and different cement contents. The second phase focused on the study of bond strength of high strength concrete using double pull-out test to assess design ultimate bond stress. In this phase, the effect of concrete compressive strength, bar diameter, concrete cover, embedded length, and pre-flexural crack length was studied. Based on the test results, a proposed concept to assess design ultimate stress of normal and high strength concrete was adopted. Equations to calculate the design ultimate bond stress, and required development length were suggested.