Journal of Engineering

This review paper explores the use of recycled brick waste (RBW) as a partial replacement for cement and fine aggregates in concrete production. The study highlights the growing interest in recycling brick waste due to the significant amount of construction and demolition waste generated annually. The performance of RBW in concrete is evaluated in terms of mechanical strength and durability properties. It was found that RBW can be used as a cement replacement up to 10% due to its pozzolanic activity, and as a fine aggregate replacement in limited quantities. The use of RBW in concrete production not only reduces environmental pollution but also enhances certain properties of concrete, making it a viable option for producing environmentally friendly concrete.

This paper investigates the performance evaluation of two state feedback controllers, Pole Placement (PP) and Linear Quadratic Regulator (LQR), designed for a Mass-Spring-Damper (MSD) system. The state space model of the MSD system is first developed. Then, two meta-heuristic optimizations, Simulated Annealing (SA) optimization and Ant Colony (AC) optimization, are utilized to optimize feedback gains matrix K of the PP and the weighting matrices Q and R of the LQR to stabilize the MSD system and reduce the oscillation of the response. The Matlab software is used for simulations and performance analysis. The results show the superiority of the state feedback based on the LQR controller in improving system stability, reducing settling time, and reducing maximum overshoot. Furthermore, AC optimization shows significant advantages for optimizing the parameters of PP and LQR and reducing the fitness value in comparison with SA optimization.

This study explores the use of fly ash as a supplementary cementitious material in reactive powder concrete (RPC) to achieve sustainability in civil engineering. The experimental program involved replacing fly ash with 8%, 12%, and 16% by cement weight to determine the optimal ratio for the best mechanical properties of RPC at 7, 28, and 90 days with standard curing. The results showed that an 8% replacement of fly ash achieved the highest compressive strength (96.5 MPa), tensile strength (9.38 MPa), and density (2395 kg/m³) at 28 days. The study concluded that it is possible to develop RPC using fly ash with high withstand stress, tensile strength, and density.

This research focuses on studying the morphology and sediment transport of the Diyala River using HEC-RAS software. The selected length of the river in the study is 193 km, extending from Diyala Weir to the confluence of the Tigris River and Diyala River. Fieldwork was conducted from June 2020 to August 2020, during which suspended-load and bed-load samples were collected, and some cross-sections were surveyed. The one-dimensional sediment transport model was calibrated for five years, from 2014 to 2019. The results were compared with the measured cross-sections in 2019, and the suitable value of maximum depth was determined to be 120 cm for five years. The simulation results for the sediment model under real conditions from 2018 to 2019 showed an invert change ranging from 0.2 m to 0.6 m. The daily and yearly sediment discharge was found to be 227.7 tons/day and 83,531.93 tons/year, respectively. The study also simulated five successive flood years, resulting in invert change values ranging from -1.25 m to 1.4 m. The river's capacity was improved by raising the riverbank level for parts of the reach and/or training the cross-sections for other parts.

This research analyzes the level of the short circuit effect of the Iraqi super network and decides the suitable location for the High Voltage Direct Current (HVDC) connections in order to obtain the best short circuit reduction of the total currents of the buses in the network. The proposed method depends on choosing the transmission lines for Alternating current (AC) system that suffers from high Short Circuit Levels (SCLs) in order to reduce its impact on the transmission system and on the lines adjacent to it and this after replacing the alternating current (AC) line by direct current (DC) line. In this paper, Power System Simulator for Engineering (PSS/E) is used to model two types of HVDC lines in an effective region of Iraqi networks and to perform comparative studies to test the location of Short Circuit Levels (SCLs) between an actual AC and AC/DC case study in a portion of the Iraqi national network. The results proved the effectiveness of this method in eliminating severe faults and unwanted short currents, and the results showed that the bipolar type is better in reducing Short Circuit Levels of the Iraqi network.

This study investigates the effect of tube rotation on the melting process in a shell and tube latent heat energy storage (LHES) system using paraffin wax as the phase change material (PCM) and water as the heat transfer fluid (HTF). The numerical simulations and calculations were conducted using ANSYS Fluent software. The study compared the melting process for a stationary case and a case with a tube rotation speed of 9 rpm. The results showed a slight increase in the liquid content of the PCM due to tube rotation, with an enhancement percentage of 3.5% over a 6-hour charging process. The heat transfer in the axial direction was found to be much smaller compared to the radial direction.