Microgrids interconnectivity has a significant impact on the performance of interconnected microgrids. This study aims to define the distributed network (DN) optimal interconnection problem to minimize both the undesirable voltage dips and the overall costs through optimal deployment and proportioning of solar facade and rooftop PVs. With the unpredictability of the loads and the PV-captured energy, the capability of these optimizers remains a research issue. Initially, to address the optimal interconnectivity issues of contemporary DNs, this study proposes a novel modified optimization framework. Under the investigated framework, several recent meta-heuristic algorithms (AO, SMA, WHO, PSO) are developed to find the optimal locations for the solar PVs. Secondly, to confirm the geographical independence of the developed framework for improving the DN performance, the hourly meteorological data is utilized to rescale the facade and rooftop PVs at several distinct locations. Furthermore, the ratio between the facade and rooftop solar PVs is determined by techno-economic feasibility analysis. Ultimately, the Spearman and correlation coefficients are used to investigate complementarity and the relationship between the facade and rooftop PVs’ irradiation patterns and capacities. The flexible deployment of PVs on the roof and the facade of the buildings has substantially enhanced the voltage profile of the DN. In response to such enhancement, the techno-economic viability records facade ratio with respect to the rooftop type of (21.5%:78.3%) in Paris, France, compared to (15.9%:84.1%) in Neom, Saudi Arabia. In terms of meeting the objective function and enhancing the performance of the expansive 295-bus system, the WHO optimizer outperforms the other algorithms.

The paper proposes an energy management system, which considers the efficiency of the reversible pump/turbin-e that varies nonlinearly depending on the water flow rate during the pump/turbine modes of operation. A vibration avoidance strategy of the reversible pump hydro storage is developed. A probabilistic approach based on artificial neural networks and Naive-based is used. Through minimizing the levelized Cost of Energy (COE), this study shows the optimal size and reconfiguration of the HMG system as well as purchased/sold energy. Two novel modified optimizers based on the Particle Swarm Optimization (PSO) and the Aquila Optimizer (AO), namely: AO initialized PSO and AO updated PSO are developed. The results via the PSO and AO optimizers are compared in terms of reducing the COE and attaining a low execution time. Based on the results, a COE of 0.22 $/kWh through the developed strategy could be obtained with CO2 emissions of 1974 ton/year against 0.24 $/kWh and 2460 ton/year using the PSO, which saves 24.6% of the yearly CO2 emissions. Furthermore, the vibration avoidance strategy avoids the dead zones and enables the reversible pump/turbine machine to operate at higher efficiencies — both of which are impossible to achieve in the occurrence of vibrations.

The presence of communication networks inside load frequency control loops exposes them to cyber–physical attacks, particularly denial-of-service and deception attacks. Potential cyber–physical attacks on power systems degrade the control performance or even cause instability. This paper proposes a blockchain-based solution against denial-of-service attacks to secure resilient smart systems. A multi-area-based PI-controllers microgrid system is examined. To protect access to the shared blockchain, a proof-of-work private blockchain approach is developed. During denial-of-service attacks, the proof-of-work based blockchain approach safeguards a copy of all data amongst smart grid parts and thus restores the true information. An H∞ control approach is developed to mitigate the uncertainty of the denial-of-service intrusions. Numerical simulations demonstrate the superiority of the proposed blockchain based H∞ controller in comparison to traditional controllers in safeguarding power systems against denial-of-service attacks.

Under earthquake excitations, reinforced concrete (RC) columns could be subjected to lateral drift reversals and a combination of axial forces, bending moments, and torsional effects. This paper investigates the behavior of glass fiber-reinforced polymer (GFRP)-RC columns under seismic-simulated loading, including torsion, which has not been studied previously. Seven large-scale circular GFRP-RC column-footing connections were cast and tested under various combined reversed cyclic loading configurations to examine the effects of torsion-bending moment ratio (tm), transverse reinforcement ratio, and concrete compressive strength. The test results revealed that increasing the tm reduced the lateral load capacity and deformability of the GFRP-RC column, but resulted in a more symmetric torque-twist relationship. Increasing the transverse reinforcement ratio mitigated core damage and provided additional support (for example, spiral turns) for torsion-induced tensile stresses. Moreover, increased concrete compressive strength bolstered torque capacity and torsional stiffness, while, under a tm of 0.4, it resulted in decreased twist capacity. When torsion was present, increasing the concrete compressive strength had an insignificant impact on the bending-shear response, differing from findings for GFRP-RC columns subjected to seismic loading without torsion.

This study presents the results of an investigation into the seismic performance of six large-scale concrete circular columns reinforced with glass fiber–reinforced polymer (GFRP) reinforcement. Among these columns, one underwent concentric reversed cyclic lateral loading, causing bending and shear, while the remaining five columns experienced eccentric cyclic lateral loading, causing additional torsional stresses. The test variables included the torsion-to-bending moment ratio, transverse and longitudinal reinforcement ratios, and concrete compressive strength. The test results indicated that the concurrent cyclic torsion and lateral drift reversals significantly altered the behavior of concrete members in terms of mode of failure, lateral load resistance, drift capacity, and energy dissipation. It was found that adequately confined columns exhibited a notable reduction in concrete core deterioration, thereby preventing the decline in both bending and torsional strength. Furthermore, the paper examined the validity of the North American design provisions predicting the torsional strength of GFRP-reinforced concrete members subjected to combined seismic loading. Amendments to the GFRP tensile stress limits specified in these provisions were introduced, yielding better and safer predictions for the torque capacity of the tested columns.

This study assesses the agronomic and economic advantages of replacing traditional flood irrigation with drip irrigation for sugarcane cultivation in water-scarce Upper Egypt. Confronting severe water shortages and inefficient conventional practices, we conducted a three-year comparative field study assessing crop yields and water use efficiency. The results reveal that drip irrigation improves water-use efficiency by 44% and increases sugarcane yields by 22% relative to flood irrigation, while also elevating net profits by 50%. Drip irrigation demonstrated an average efficiency of 85–90%, compared to 50–60% for flood irrigation. These findings underscore the dual benefits of drip irrigation in addressing water scarcity and enhancing agricultural productivity. The study provides compelling empirical evidence supporting drip irrigation as a sustainable solution for arid regions. To ensure long-term water resource sustainability and food security, we urge policymakers and agricultural stakeholders to prioritize large-scale adoption of drip irrigation systems through targeted investments and policy interventions.

ABSTRACT: One of the problems facing the underground tunnels is lacking enough fresh air for passengers inside the subway. Also, because of the friction of the train with the railways, high heat is generated. So, the use of computational fluid dynamics to

distribute the required fresh air flow at the lowest possible cost is critical for the tunnels. In this research, Computational Fluid Dynamics (CFD) is used to perform 3D modelling and simulation for the tunnel of Cairo Metro Line No. 3. The standard k-e

turbulence model was used in the CFD analysis to simulate the ventilation airflow in a 1075m tunnel length. The simulation reveals that the tunnel airflow rate induced by the speed of the fan is more desirable. Also, the addition of a jet fan causes an eddy current that improving the efficiency of tunnel ventilation, thereby greatly reducing ventilation time, and increasing

efficiency in cases where the diameter of the tunnel equals 15 m, the speed of the fan is 1480 r.p.m, and the air flow rate is 80-

120 m³/s. This led to improve fan speed efficiency and airflow distribution in the tunnel. Similar way of simulation is used for

road tunnel ventilation.

Abstract

Due to the problem of lacking enough fresh air for passengers in underground metro stations, increasing attention has been paid to improving ventilation in underground metro stations. In this paper, the distribution characteristics of airflow fields, geometry of the station, and the influence of airflow rate changes on passengers’ ventilation conditions have been investigated and simulated according to computational fluid dynamics (CFD) theory. In addition, the volume of the stations was treated with a central air conditioning system, including several air handling units (AHU) connected to chilled water. Air flow for trains and stations has been calculated and compared with the actual data of the National Authority for Tunnels (NAT). It has been found that the highest air flow rate Q for Attaba station is 24.97 m³/s at ticket hall level, and the lowest air flow rate is 5.23 m³/s at platform level. Also, the required air flow rate is 111.02 m³/s for trains has been calculated. This value is acceptable and suitable in comparison to the actual results from the NAT. This is to reduce the necessary heat and improve the air quality inside underground metro stations. It is concluded that, in cases where an air flow rate is required in stations, the efficiency of the fans must be superior to 70%. The rotation speed of the fans will range from 750 to 1480 revolutions per minute (r.p.m).

Abstract

One of the problems of tunnels is lacking enough fresh air for passengers inside the subway. Also, because of the friction of the train with the railways inside the tunnel, high heat is generated. So, the design and calculation of an efficient ventilation system are critical for the tunnels. There are several methods used to determine the most effective tunnel ventilation systems while reducing fan energy costs, including their operating performance. The main task of an optimal tunnel ventilation system is to determine the quantity, location, and function of fans to distribute the required fresh air flow at the lowest possible cost. The main parameters for selecting a suitable fan that meet the optimal design of the tunnel ventilation system are the ventilation rate (Q) and the static head pressure (H). Both Q and H of Cairo Metro Line 3 were studied and calculated under different conditions of ventilation design from the obtained data. The amount of the ventilation rate by the fan was taken 80 m3/s which is the actual air flow rate taken from data of the National authority of Cairo Metro No.3. In addition, a comparison is made between various methods to determine the most effective tunnel ventilation system. The static head pressure (H) was calculated. According to the American Brattice Cloth (ABC) rigid duct method, the static head equals to 1171.5Pa, which is the most economical value that is giving the lower power consumption and rate of ventilation.