Journal of Engineering and Sustainable Development (JEASD)

The objective of the presented study is to examine the effects of glass fiber reinforced polymer (GFRP) composite as rehabilitation systems on the fatigue performance of reinforced concrete beams. Experiments were conducted on beams with and without GFRP composite sheets on their tensile surfaces. The specimens were 152 X 152 X 1,321 mm reinforced concrete beams with enough transverse reinforcement to avoid shear failure. The results of this study indicate that the fatigue life of reinforced concrete beams with the given geometry, subjected to the same cycling load, can be significantly extended through the use of externally bonded GFRP composite sheets. An interesting finding is that, although the fiber strengthening system increases the fatigue life of the beams, the failure mechanism, and fatigue of the steel reinforcement, remains the same in both strengthened and non strengthened beams. Thus, it is possible to predict the fatigue life of a cyclically loaded beam using existing fatigue models.

The design of complex dynamical systems involving multi-loop configurations demands an appropriate choice of parameters that must match together to provide an acceptable system. This is investigated by the development of a simulation that provides a conceptual implementation of such systems and verifies the told behavior before its construction. The potential of the approach is explored by applying it to a problem in engineering practice. The approach permits experimentation with different combinations of system elements, parameters, and constraints. The efficiency of the approach suggests its suitability as a general way to start the practical design of these systems. Index terms design of complex control systems, simulation complex dynamical systems, nonlinear control, and digital control systems.

This study presents experimental and theoretical investigation performed to investigate the shear behavior of reinforced concrete beams without shear reinforcement (stirrups) and with full or partial steel fiber reinforced concrete (SFRC) shear span.More rational way has been used by replacing (strengthening) a certain part(s) of shear span by steel fiber reinforced concrete (SFRC). Tests were carried out on four beams, simply supported under single point loading. One of which were made fully with NSC, and the others were made fully or partially with SFRC in shear spans.Experimental results show that the ultimate shear strengths are increased by (17% -150 %), while the reserve shear strength is increased by (18.2 % - 48.8 %) for tested beams strengthened with SFRC, in comparison with the reference beam. Crack arrest mechanism of steel fibers limits crack propagation, improves reserve strength and alters the mode of failure. So, more safety was obtained.ANSYS finite Element package program are used to simulate all tested beams. Three dimensional nonlinear brick element (solid element) was utilized to model the concrete, while, the steel reinforcement was modeled by using a discrete representation (bar element).It was found that the general behavior of the finite element models shows good agreement with the experimental tests results.

The Telemetry/Telecommand Transponder is the unit on board a satellite that maintains the communication link between the satellite and the control center on the Earth. The spacecraft includes service telecommunications Telemetry and Telecommand (TMTC) and On-Board Supervision (OBS) subsystem to provide telemetry, telecommand and ranging functions during all phases of the mission. The function of transponder, generally, is receiving the uplink signal modulated with telecommand and ranging tones, process it, and transmit the downlink signal (at different frequency) modulated with telemetry and ranging signal to the ground station. In this research, European Space Agency's recommendations and standard have followed to calculate the coherent transponder parameters. The coherent transponder and the related communication functions have been simulated using MATLAB Simulink software version 6.5. The computer simulation was necessary to show the performance of such functional block under the influence of many parameters like Doppler shift, input signal level variation, and damping factor variation.

The search for a material, which is to be, light and at the same time strong, has resulted in the use of high strength, high modulus fibers reinforced in low strength, low modulus, and low-density matrix material which is called composite material. The finite element models and numerical results are presented for the impact of composite plates using a Special Third Order Theory (HOST 7) with the parabolic distribution of the transverse shear strain through the thickness of the plate and rotary inertia effect is taken into account. The Newmark direct integration method is considered for the solution of the linear dynamic response of the system. A typical finite element mesh of the quarter model is considered because of the double symmetric. A nine-noded Lagrangian element is chosen as a discretization element with seven degrees of freedom per node. The effect of the velocity and mass of the impactor, number of layers, degree of orthotropy (E1/E2), lamination angle, aspect ratio (a/b), and the boundary conditions on the dynamic response of the laminated plate is considered. The results show that the orthotropic ratio, velocity, and mass of the impactor have a significant effect on the deflection of the plate under impact load. In addition, the calculation of the dynamic load factor is presented.

The continuous increase in the concrete strength has called for adapting and amending the rectangular stress block parameter values recommended by provisions. This study reviews several different mathematical stress-strain models and adopts a numerical technique through which a complete stress-strain curve characteristic for any strength is determined. The study highlights the effect of the stress-strain model on equivalent stress block parameters. The paper illustrates the variation of the new parameter values against concrete strength and those of provisions and other studies. For safe, economic, and vast use; the author suggests two formulas to calculate modified stress block parameters.

Serial concatenated convolutional coding with iterative decoding is examined for data transmission employing BFSK (binary frequency shift keying) modulation and non-coherent detection receiver.
The core of the iterative decoding structure is soft-input soft-output (SISO) module. In this paper, the performance of serial concatenated convolutional codes (SCCCs) is evaluated by simulation over frequency selective Rayleigh and Rician fading channels.
Simulation results show that, for both frequency selective Rayleigh and Rician fading channels, better BER (bit error rate) performance could be obtained when the outer encoder is a non-recursive (NR) encoder and the inner encoder is a recursive (R) encoder

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In this work, the vibration characteristics of cantilever blades are studied; natural frequencies are evaluated for different aspect ratios. Other parameters like thickness taper and width are considered.
The experimental results are compared with numerical results using finite element method (ANSYS 5.4 package) these results give good agreement and show the effect of the aspect ratio on the natural frequency

Compressive strength and modulus of elasticity of plain and steel fiber reinforced concrete, both before and after exposure to high temperatures were investigated in this study. Two fiber volume fractions of 0.5% and 1.0% were used. Three temperature levels of 150 oC, 350 oC and 500 oC were adopted in addition to room temperature.The test results showed that compressive strength and modulus of elasticity decreased after high temperatures exposure. At 350 oC, the plain concrete recovered some of the lost strength at 150 oC, while fiber reinforced concrete showed a slight additional decrease in strength at 350 oC as compared to 150 oC. Only minor loss in modulus of elasticity occurred at 150 oC for both plain and fiber reinforced concrete, which was limited to about 11%. While at 500 oC, significant deterioration occurred. The residual modulus of elasticity at 500 oC was in the range of 31% to 42%.

Results of numerical and experimental study on the turbulent mixing layer of three-dimensional non-parallel streams are reported. The numerical prediction was based on k- model. Fully elliptic Navier Stokes and energy equations are solved using finite difference primitive variables method. The study has been carried out at Reynolds numbers, Re = 19200, 28000, 48000, and three velocity ratios U1/U2 of 0.3, 0.5, and 1.0. The flow studied. The mean velocity and temperature profiles are studied up to 42 orifice width down stream from the of the high speed side is heated and the flow of the low speed side is kept at room temperature.Two interception angles of (12.5o, 25o) were orifice. The results show that there was significant effect of the angle and the mixing ratio on the characteristics of the flow field. The two jets are merged upstream of their geometric interception. The centerline of the combined jet is tilted from the midline between the two orifices when the two jets have different velocities at the large interception angle. Also the results indicated that the mixing layer penetrated deeper into the low speed side than into the high speed of the flow. The numerical results are compared with the experimental results and found to be in moderate agreement.

This paper proposes on a project whose aim is to implement architectures for Constant False Alarm Rate (CFAR) processor employed in radars. These proposed architectures are implemented by using Field Programmable Gate Array (FPGA) technique, with observance of feature desired as flexibility, and speed without performance loss. This design written in VHSIC Hardware Description Language (VHDL).FPGA architecture of TM-CFAR processor is implemented to overcome the large processing time required in case of multi-target environment. The use of this technology is suitable because it offers high flexibility in modifying and even developing the required design with a reduction in the required number of hardware and cost.In addition to the main features of the processing chain architectures such as degree of parallelism, small size, accuracy and high computational speed, there is a requirement for generality and adaptively i.e. the ability to handle many different models of operation in different environments.The implementation of the design is achieved using Xilinx Virtex-II platform as a suitable selected programmable device. The development of the system software for this work has been done using Active HDL 3.5, and ISE Navigator 6.3i programs

Simulation results for the resistance modulation in metal-semiconductor field effect transistors (MOSFETs) are presented. The numerical simulations show that the resistance fluctuation does increase as the trap area is reduced, passes through a maximum and finally decrease towards zero. The comparison of the simulated results with typical experimental Random Telegraph Signal (RTS) data shows an overall good agreement.

This study is concerned with the effect of adding two kinds of ceramic materials on the mechanical properties of (Al -7% Si) alloy, which are silicon carbide of particle size (25μm > P.S ≥ 0.1μm) and boron carbide of particle size (20μm > P.S ≥ 0.1μm) and adding them to the alloy with weight ratios (0.2,0.4,0.6,0.8,1 %). Stirring casting method has been used to make composite material by using vortex technique which is used to pull the particles to inside the melted metals and distributed them homogenously. After that solution treatment was done to the samples at (520ºC) and artificial ageing at (170ºC) in different times. It has been noticed that the values of hardness are increased with aging time of the base alloy and reached its highest value after (8hr).Mechanical tests were done to the original alloy and the composite material at the maximum hardness value and represented by tensile, hardness, and wear tests. It was found that the hardness value is increased with increment of the amount of added particles; also the increment in the hardness of the alloy which is reinforced with boron carbide is more than that reinforced with silicon carbide. Regarding the tensile test, results shown that the strength and yield resistance of the composite material are more than that in the base alloy and these values are increased with increasing of the added particles and they reached maximum values at (0.6%). Then they are decreased....

The concept of the modern maintenance management has been developed in parallel with the international development of the science and technology, especially targets identification of the management, and it’s duties in the hydraulic establishments.The research included a real state study of maintenance management activities of Himreen dam to propose a suitable maintenance management system. Also it presented a description of the dam importance and discussed the concept of the modern maintenance; definition, classification, and the analysis of the four factors of management system which are (planning, organizing, directing and controlling).The field survey included preparing the questionnaire list, conducting the statistical analysis for its axes, and discussing the results.Many conclusions and recommendations have been deduced which related to the applications of the maintenance management in the dam project, and to generalize the proposed system in future to all dam’s projects in Iraq