Journal of Engineering

This study investigates the thermal and electrical efficiencies of a designed Photovoltaic Thermal (PVT) hybrid solar water collector under different weather conditions. The system includes a fabricated cooling system with serpentine tubes attached to a single PV panel, connected to an automatic controlling system for data collection. A removable glass cover was used to compare the efficiencies of glazed and unglazed PVT panels. The research was conducted in February (winter), July (summer), and March (daily solar radiation effects). Results showed increased electrical and thermal gains with higher solar radiation. The thermal energy efficiency of the PVT collector with a glass cover increased by an average of 5% compared to the unglazed collector.

In the current analysis, the effects of circumferential scratches along the inner surfaceof a 170ᵒ-arc partial journal bearing has been numerically investigated.Their impact on the thermo-elasto-hydrodynamic performance characteristics, including maximum pressure, temperature, deformation,and stress, has been examined thoroughly. The ANSYS Fluent CFD commercial codewas employed to tackle the iterative solution of flow and heat transfer patterns in the fluid film domain.Theyare then applied to the ANSYS Static Structure solver to compute the deformation and stress resulted in the solid bearing zone.A wide range of operating conditions hasbeen considered,including the eccentricity ratio (0.8236≤????≤0.9866) and scratch depth (0????????≤ℎ????≤0.224????????). In contrast,the bearing length-diameter ratio (L/D) andthe rotation speed (N) have been fixed at 0.77 and 1500 rpm, respectively. The thermo-hydrodynamic pressure, temperature, stress,and deformation have all been computed. It was found that the scratch depth has a direct effect on thethermo-hydrodynamic performanceof the partial bearings. Meanwhile, the deep central scratches are important, especially at scratch depth equal to0.224mm.

This paper investigates the hydraulic behavior of flow in open channels using large-scale geometric roughness elements. The study uses ANSYS Parametric Design Language (APDL) and Computational Fluid Dynamics (CFD) to simulate the flow and analyze the effects of different configurations of roughness elements on velocity distribution and hydraulic characteristics. The results show that increasing the number of roughness elements enhances flow resistance, which can help control erosions and sedimentations. Various configurations were tested, including T-shape roughness elements with different line arrangements, demonstrating significant changes in velocity and hydraulic performance.

This paper investigates the strengthening of cracked one-way bubbled slabs using external prestressed strands. The analysis was conducted using ABAQUS 2017 software on six simply supported specimens, with five containing 88 bubbles and one solid slab as a reference. The slabs were subjected to service load, external prestressing, and loading to collapse under two line loads. The results showed that each reinforcement approach restored the initial capacity of the bubbled slab and improved its ultimate load capacity. The minimum and maximum ultimate strength of the strengthened cracked bubbled slab increased by 17.3%-64.5% and 25.7%-76.3% compared to the solid and bubbled slabs, respectively. Increasing the eccentricity of the prestressed wire was found to be more effective than increasing its length.

This paper investigates the catalytic cracking of furfural extract-40 using a Ni/HY-zeolite catalyst. The study involved characterizing the HY-zeolite and nickel-promoted catalyst using X-ray diffraction, Scanning Electron Microscopy (SEM), BET analysis, and FTIR. A fixed-bed tubular reactor was used for the thermal catalytic cracking at 580°C with an LHSV of 5h⁻¹. The results showed increased conversion and yield of useful petroleum products with the Ni/HY-zeolite catalyst, while coke formation was reduced.

his paper deals with a Twin Rotor Aerodynamic System (TRAS), a Multi-Input Multi-Output (MIMO) system with high cross-coupling between its two channels. It proposes a hybrid design procedure that combines frequency response and root locus approaches. The proposed controller is designated as PID-Lead Compensator (PIDLC); the PID controller was designed in previous work using frequency response design specifications, while the lead compensator is proposed in this paper and is designed using the root locus method. A general explicit formula for angle computations in any of the four quadrants is also given. The lead compensator is designed by shifting the dominant closed-loop poles slightly to the left in the s-plane. This has the effect of enhancing the relative stability of the closed-loop system by eliminating the oscillation in its transient part but at the expense of greater rise time. However, for some applications, long rise time may be an allowable price to get rid of undesired oscillation. To demonstrate the proposed hybrid controller's performance numerically, a new performance index, designated by Integral Reciprocal Time Absolute Error (IRTAE), is defined as a figure to measure the oscillation of the response in its transient part. The proposed controller enhances this performance index by 0.6771%. Although the relative enhancement of the performance index is small, it contributes to eliminating the oscillation of the response in its transient part. Simulation results are performed on the MATLAB/Simulink environment.

This paper investigates the propagation of mistakes in architectural design, focusing on residential buildings in Al Sulaymaniyah City. The study examines how the experience of architectural designers influences the occurrence and propagation of mistakes. The research identifies the main reasons and influences behind architectural mistakes and uses randomly selected samples of residential buildings designed between 2000 and 2010 as case studies. The findings highlight the importance of designers' experience in minimizing mistakes and ensuring adherence to architectural design values.

This paper investigates a robust video-bitrate adaptive scheme at the client-side to maintain a good quality of video streaming technology experience. The study formulates the video buffer structure as an optimal control-theoretic problem that combines video bitrate and video buffer feedback signals. To protect the video buffer occupancy from exceeding the limited operating level, two thresholds are added as operating points for overflow and underflow states. A bandwidth prediction algorithm is proposed to enhance the performance of video bitrate adaptation, depending on the current video buffer level, video bitrate of the previous segment, and iterative throughput measurements. Simulation results show that reserving a bandwidth margin is better in adapting the video bitrate under bandwidth variation, reducing the risk of video playback freezing. The proposed scheme outperforms other schemes such as smoothed throughput rate (STR) and Buffer Based Rate (BBR) in attaining smooth video bitrates and continuous video playback.

This paper examines the classical technique of open channel flow measurement using the integrating-float method. Due to the shortage of water resources and the high cost of modern devices, this method was revisited. The study defines the parameters affecting the acceleration of floating spheres in flowing water and analyzes these parameters using experimental measurements. Different sizes of solid plastic spheres with varying weights were used as floats to measure velocities and compute discharge. The results indicate that the integrating-float technique is feasible and accurate for measuring low flow velocity in open channels. Small floats with specific gravity closer to unity provided more accurate results. The measured velocities and estimated discharges were compared with those obtained using other common laboratory measuring techniques, showing good agreement with an error of less than 2.5%.