Journal of Engineering and Sustainable Development (JEASD)

The experimental and numerical investigation has been performed in this work to evaluate the performance of the U-longitudinal finned tube heat exchanger. Four pairs of U-shaped longitudinal fins were selected and manufactured from copper material and welded on the straight copper tube. The inner tube is inserted inside the insulated galvanized tube, and sheet and roll insulation (arm flux) and glass wool have been utilized to cover the inner and outer surface of the galvanized tube for reducing heat losses. Air at various mass flow rates (0.03 to 0.07)kg/sec flows through annuli and de-ionized water at Reynold's numbers ranging from (270 to 1900) flows through the inner tube. The performance of (smooth and finned) tube heat exchanger was investigated experimentally. Experimental results showed a (1.744 to 2.534) enhancement ratio when using U-longitudinal fins. Empirical correlations for air and water were represented by Nusselt's number. Numerical simulation has been carried out on the present heat exchanger to analyze flow field and heat transfer using FLUENT package 14. The comparison between experimental work and numerical results showed good agreement.

This paper studies the properties of normal and high strength self-compacting concrete in the fresh and hardened states, six self-compacting with normal and high strength concrete mixes were prepared with different percentages of fibers(0, 0.4%, and 0.8%) were used to find out the effect of the addition of steel fibers on the properties of self-compacting concrete in the fresh state (Filling ability, Passing ability, and Segregation resistance) and hardened state (compressive strength, splitting tensile strength, modulus of rupture, and modulus of elasticity) of concrete. The study shows that the addition of steel fibers in self-compacting concrete enhances compressive strength, tensile strength, modulus of rupture, and modulus of elasticity relative to self-compacting concrete cast without steel fibers for both types of self-compacting concrete strength (normal strength (NSCC) and high strength (HSCC)).

this study presents a solution of electromagnetic scattering from an arbitrarily oriented thin-wire excited by an incident electromagnetic plane wave by using the Method of Moment (MoM). The solution for the axial current is obtained. The application of the Method of Moment (MoM) solution to the thin wire integral equation is obtained by enforcing the boundary condition on the electric field; this method inherently produces a full and dense matrix. The numerical results are performed for validation of the efficiency and accuracy of the proposed method.

Friction stir processing is a new method of changing the properties of a metal through intense, localized plastic deformation ,this process mixes the material without changing the phase (by melting or otherwise) and creates a microstructure with fine, equiaxedgrains , It is used to improve the microstructural properties of metals. In this paper , the enhancement of mechanical properties of friction stir welding specimens at variable rotation speeds (1500,1700 and 1900 rpm ) with constant feed speed(40mm/min) for 7075-T73 aluminum alloy is studied by using the friction stir processing method at the same variable rotation speed and feed speed in order to transform a heterogeneous microstructure to a more homogeneous, refined microstructure.The best results of the weld gained at the parameter 40 mm/min weld speed and 1700RPM rotation speed for the friction stir welding (FSW) and friction stir processing (FSP) where the efficiency reaches to 83.7% for FSW and 92.99% for FSP of the ultimate tensile strength of the parent metal.

This paper presents an experimental investigation consisting of casting and testing in flexure twenty four rectangular simply supported reinforced concrete beams.Three of the tested beams are made with conventional concrete (CC), five with reactive powder concrete (RPC) and sixteen as hybrid beams of the two concretes. RPC is used in tension in ten hybrid beams and in compression in the other six beams. Experimental results have generally shown that higher ultimate loads (Pu) are obtained with the increase of RPC layer thickness (hR/h), steel fibers volumetric ratio (Vf) and longitudinal steel ratio (ρ) for hybrid beams with RPC in tension as well as in compression. However, the effect of (ρ) is more pronounced than the other factors. Using RPC in compression is found to be more effective than using RPC in tension. The increasing ratios for ultimate loads of hybrid beams with RPC in compression, ρ=3.36% and Vf= 1% (compared to CC beams) are 47.13% and 71.97% for (hR/h) of 0.25 and 0.5, respectively. These ratios are higher than those for hybrid beams with RPC in tension, ρ=3.36% and Vf= 1%, for hR/h of 0.25 and 0.5 by 35.67% and 37.58%, respectively.

In this research, road pavement condition was investigated for Aborshada road in the Gharian region to determine the best maintenance works. Previously, Simple engineering judgment was the only procedure followed by Gharian Municipality engineers for pavement evaluation and maintenance prioritization. Aborshada road pavement surface condition was investigated by using the visual technique “ Pavement Condition Index (PCI)”, to survey the different distresses and classified according to the PCI standards (ASTM standard in 2007 (D6433-07)). Also, to know the most common distresses in the Aborshada road to provide assistance for decision-makers in the pavement evaluation and best selection of repair methods. In this study, pavement condition evaluation techniques, scenario maintenance decision, and detail sheets for some distresses types in the Aborshada road was presented. Based on the pavement condition evaluation, the decision-maker can find the effect of the maintenance works on the existing pavement condition. Also, can select the best alternative, which is suitable for the fund. This study reveals pavement's actual performance and suggests the required research, which deals with the pavement maintenance problem in Libya, especially in the western region. This study showed that the best maintenance alternative for Aborshada road was case No. 4 (Potholes, Long. & Trans. Cracking and Alligator Crack Maintenance). Also, this study showed that the most common pavement distresses on Aborshada road were distresses No. 13, 10, 1, 3, 7, 6 according to ASTM – D6433-07 classification.

Viscoelastic contact problems are one of the most important problems in mechanical and robot engineering. These problems become more tedious when one of the contacting bodies carries a viscoelastic and soft material. In this study, the mathematical model of contact interface and limit surface for viscoelastic contact which can be applied to robotic and prosthetic hemicylindrical fingertips has been proposed. The new achievement of this research comprises the integration of the time-dependent nature of viscoelastic contact into the modeling of grasping and manipulation. Specifically, two conjugation equations to get together the two significant parameters of contact modeling (the half-width of the rectangular contact area and the profile of pressure distribution across the contact interface) have been suggested. Additionally, two cases viable for prosthetic and robotic hands for grasping have been studied: constant rectangular contact area and constant normal contact force. The results show that the control of the grasp contact forces (case 2) when employing viscoelastic contacts is most advantageous because it promotes the stability of grasping through the enlargement domain of the limit surface as time terminates. Finally, the viscoelastic limit surface results proved that the new mathematical model is more effective (18-22%) than previous models.

This paper reports research in which an attempt was made to predict a mathematical model of hardness for steel-52100. The primary objective was to investigate the effect of heat treatment parameters on the hardness of steel-52100, where the value of hardness is influenced by these parameters (Austenitizing temperature, tempering temperature, and tempering time). To determine the influence of these parameters, experiments were conducted using Taguchi's orthogonal array. The results of these experiments were used to plot the response graph, and Pareto diagram and to calculate S/N ratios. An empirical model for the hardness in terms of the parameters mentioned was also developed. Coefficient of determination was used to check the adequacy and accuracy of the model. The empirical model so developed was checked by conducting confirmation experiments. Contour plots were plotted to visualize the effect of those heat treatment parameters on the hardness. Those parameters were optimized to maximize the hardness using the larger-the-better concept of robust design and also compared with the optimized parameters obtained using the developed empirical model. Finally, this study shows a good agreement between the mathematical model and experimental results.

An exegetical thermodynamic model was used to analyze and optimize reciprocating and scroll compressors of an air condition packaged unit. The experimental work was carried out using a 3.0 TR packaged unit manufactured by Carrier Company. The experimental and the analysis show that the exergy dissipative due to friction losses in bearings, suction, and discharge valves, and the transformation of power is larger than the heat losses. The exergy efficiency of the compressor was varying between (60-68) %. The scroll compressor was found to be better than the reciprocating compressor at an environmental temperature of 35℃ due to its low total losses which are 10% less than the reciprocating compressor ones. The heat loss percentages were 3% for scroll and 2% for the reciprocating of the total power input. The thermodynamic model has been shown to be reliable in dealing with a change in the environmental temperatures and such system components and size.

In this paper, an overview of the Long Term Evolution (LTE) is presented. LTE is the development of the Universal Mobile Telecommunications System (UMTS). It allows mobile users to access the Internet through their devices (mobile telephones, laptops…). LTE intends to deliver high-speed data and multimedia services to the next generation. The main contribution of this work is to propose a new LTE 3GPP Long Term Evolution Physical Layer Transceiver scheme based on Orthogonal Frequency-Division Multiplexing OFDM, Discrete Multiwavelet Transform (DMWT). The proposed Transceiver scheme has been designed and tested to investigate whether it achieves its goal. 6 SUI-channel types have been used. The simulation by Matlab approved the proposed design which achieved much lower bit error rates (BER), increased signal-to-noise power ratio (SNR), robustness for multipath channels and does not require cyclically prefixed guard interval, and has higher spectral efficiency than transceiver based OFDM on Discrete Wavelet Transform (DWT) and Fast Fourier transform (FFT) also can be used as an alternative conventional transceiver used in present time.

The main objective of the present study is to evaluate the potential use of recycled cement concrete (RCC) as filler for asphalt mixture. The large amount of construction and demolition (C&D) waste of cement concrete especially after 2003 may produce many serious landfill problems and cause environmental pollution. It is necessary to reuse this waste material to avoid such problems. In this study the recycled cement concrete (RCC) is used as filler for asphalt mixture. Laboratory tests undertaken include Marshall tests to determine the optimum asphalt content (OAC) for control and alternative mix, x-ray diffraction test, chemical composition test, scanning electron microscopy (SEM) test and static creep test. The results show that the recycled cement concrete (RCC) as filler has lower calcite (CaCO3) percent and higher quartz (SiO2) percent than ordinary portland cement. The results also indicate that the application of recycled cement concrete as filler for hot mix asphalt can improve the rutting resistance and stiffness modulus and reduce permanent strain especially in hot region. It was also concluded that the use of RCC as filler for asphalt mixture needs projects with good quality control to avoid bad compaction in the field, so it is not recommended to use this material in projects where bad quality control is exists.

In this work, the Boundary layer flow of laminar free-convection heat transfer along with an inclined flat plate with constant face temperature is numerically analyzed and solved. The unsteady, two-dimensional, non-linear, and coupled partial differential boundary layer equations of continuity, momentum, and energy governing the flow are transformed into a set of non-dimensional equations and solved by using the Crank-Nicolson method (CNM) of finite difference. The results of dimensionless velocity and temperature, and local Nusselt number (Nux) are shown graphically and discussed. The influence of thermal stratification parameter (S), Prandtl number (Pr), and inclination angle of the plate (ϕ) on the dimensionless velocity and temperature profiles on the flow and heat transfer properties have been plotted and discussed. The results of the present work are compared with previous theoretical work. It can be seen as a good agreement.

Al-Muwaffaqiyah Town lies in Wasit Governorate southeast of Baghdad City. This town is divided into two sides by the Al Gharraf River. The needing to travel between these two sides creates traffic concentration on the one existing bridge. Therefore, the construction of another bridge can help to improve the transportation network of this town. The transportation planning process (find the best route) can be considered a strategic, important, and complex issue at the same time, due to collecting information and analyzing data to reach the optimum network (journeys of shortest routes) in order to save time, to reduce cost, fuel, noise, and air pollution. By using GIS, the network can be analyzed, and found the optimum route based on the shortest travel time between the origin and destination of the journey by using the software’s algorithm. Moreover, the ability of GIS to generate detailed directions along the route, providing as-you-need-it solutions for common problems. An application of the GIS tool can help to solve this problem. So Al-Muwaffaqiyah town is divided into 13 Traffic Analysis Zones (TAZ). The center of each zone is obtained in order to compute the shortest time between every two zones. The GIS algorithm divides the network into nodes (where lines join, start, or end) and the paths between such nodes are represented by lines. In addition, each line has an associated cost representing the cost (length or time) of each line in order to reach a node...

The technique of cold recycling of asphalt pavement materials for road construction is widely used in the world. Different types of locally available stabilizing additives and/or agents were used to find the most suitable one from the point of view of strength, economy, and environment. Cubic molds of (10) cm are used in the laboratory to prepare samples of stabilized rap materials. The effect of curing mode (effect of water absorption) was studied from a strength point of view. Increasing brick sand in the stabilized RAP materials increases the compression strength because of filling the spaces. A brick sand increase reduces the absorption in case of cement stabilizing while lime increases the absorption. Dynamic modulus of elasticity decreases with bricks sand increasing. A cement ratio of more than 5% alone or more than 3% with lime is recommended to use, lime stabilizing ratio not exceed 10%.

Pavement is defined as multiple layers system and the strength of each layer is reflected on the pavement as whole. Two type of materials used as base layer, conventional granular materials and reclaimed concrete aggregate (RCA) materials. This study presents test results and discusses the effect of lime-silica fume on strength of base layer as stabilizer. Also, a comparison is made between the changes that occur in treated base layer and untreated base layer. Combination of lime - silica fume is used as stabilizer with (1, 3, 5, 7) % and also cement stabilizer is used with (0.5, 1.5) %. Comparison between treated and untreated base layer is made in terms of strength. The material of base layer is conventional base material taken from Al-Nibaee quarry. Samples with three replicates of each possible combination are performed. A total of (68) samples is prepared and subjected to compressive strength test. The obtained results indicate an increase in the strength of base material by factor of increment about (2.56) when Reclaimed Concrete Aggregate (RCA) is used. Also, at (5%) lime -silica fume stabilizer, the factor of increment increases in the strength by about (42.248) more than the untreated samples.

A common problem in hydraulic applications is the synchronization of multi cylinders that must match each other’s position. Stroke length depends on the volume of oil delivered to the cylinders, and moving them together requires equal oil flow to each cylinder as well as diameters. Oil leakages, pump slips, changing workloads, and varying friction loads could also affect oil delivery. A flow divider valve has been used to control the motion of dual actuators. To control pressure, flow rate, and displacement, pressure transmitters, flow sensors, and position sensors. Three values of oil operating temperatures (40, 45, 50) oC have been used to show the effect of the temperature and the compressibility also will be studied. Different weights have been used to produce different pressures (4, 10) bar. Matlab/Simulink will be used to represent the mathematical model of the system. Also, a schematic diagram of the hydraulic circuit has been done by the Automation studio program

The purpose of this research is to develop an empirical model for delay prediction at Signalized Intersections as a function of influence traffic and geometric features. Two Signalized Intersections with different characteristics are selected in Sulaymaniyah city. Field traffic volumes, signal timings and phasing and control delay were measured during peak and off-peak periods using video recording technique. Geometric design elements were measured through a field survey and satellite image. A statistical approach is used to develop delay model (linear regression model with 95%). The statistical analysis indicates that both geometric and traffic variables have a significant effect on delay time. The regression model, developed to estimate delay, shows the good correlation with field values. The ratio of total width of exit roadway of intersection for traffic departing straight forward to total width of lane groups departing to the same exit roadway at the same phase at stop line (We/Ws) appear to affect the delay. The ratio has a negative effect on delay time when the ratio is less than 1.0. The model has been compared with SYNCHRO delay model. It is found that although SYNCHRO delay overestimates delay at high ) v/c ( range, but it does not have a significant difference with the field delay at 95% confidence level.

Compression