The deleterious effects of noise pollution on public health have been well documented, 
with traffic noise being identified as a significant contributor to stress and adverse impacts on the 
human body and mind. In this study, sound levels at 12 different points in Al-Oqailat Park in Bu- 
raydah, Saudi Arabia, were measured using a sound level meter (SLM), with the study’s primary 
objective being to conduct this measurement. The experimental results were then compared with 
perception measurements collected from users who frequently visited Al-Oqailat park. Sound meas- 
urements were taken in four different zones (A, B, C, and D) during rush hours between 1:30 p.m. 
and 5:20 p.m. It was found that noise levels at point A1 peaked at 79 dBA at 4:40 p.m., while the 
lowest level recorded was 41.1 dBA at point D2 at 2:35 p.m. The range of noise levels varied between 
79 and 41 dBA, with a rate of decline of 48.10%. Zones A and B seemed to have the highest noise 
levels during rush hours, since they were located closest to King Fahd Road and Al-Adl Street, while 
zone D exhibited the lowest noise levels due to its location as a parking lot for Buraydah Court. An 
intermediate noise level was found in zone C, in the middle of Al-Oqailat park. The people percep- 
tion results, completed by 84 park visitors, showed that zone A was identified as having exception- 
ally high noise levels compared to the other zones, with zone D having the lowest levels. These 
results were consistent with the experimental findings and reflected that the points along King Fahd 
Road and Al-Adl Street had the highest noise levels. Overall, the research highlighted the domi- 
nance of car traffic and horns as the primary sources of noise pollution in and around Al-Oqailat 
Park, emphasizing the significance of meticulous site selection for parks in urban areas.

Arid and hot regions, like Saudi Arabia, utilize up to 60% of the country’s energy to regulate 
buildings’ indoor comfort. Energy efficiency is a long-term sustainability measure that is part of the 
government’s Vision 2030 strategy. A standard method of improving the thermal performance of 
buildings is through the use of insulation materials. Considering the cooling loads’ requirement and 
the Global Warming Potential (GWP), the present research evaluated the effectiveness of insulation 
materials, including extruded polystyrene, expanded polystyrene, rock wool, and glass wool in 
the hot, arid climate. For this case study, four similar villas facing the cardinal directions were 
selected from the residential project at Qassim University. HOBO data loggers were used to collect 
indoor temperature data. Thermal performance and Life Cycle Assessment (LCA) were conducted in 
accordance with Saudi Building Code-602 (SBC-602). Simulation outputs based on the four cardinal 
directions were used for assessing the thermal performance and LCA of the different thicknesses and 
densities of insulation materials. This was done using IESVE and SimaPro, IMPACR2002+, to assess 
their cooling load and GWP, respectively. The results suggest the potential for using lower insulation 
thickness for the northern and western façades without violating the SBC. The results obtained the 
actual thicknesses of the three insulation materials for achieving indoor temperatures in the four 
cardinal directions and the selection of materials and their densities along with associated GWP. The 
outputs of the study have been generalized in the form of a performance-based flowchart as a tool for 
selecting the type and thickness of thermal and environmental insulation in residential buildings in 
the Qassim region of Saudi Arabia.

Deadbeat model predictive control (DB-MPC) is one of the advanced promising control methods for power converters thanks to its simplicity, high steady-state performance and fast dynamic response. However, the high sensitivity to parameter mismatch and the difficulty of handling multiple control targets are problematic issues in DB-MPC. This work presents an improved robust DB-MPC for a new nine-level ANPC-based inverter. This inverter requires a low number of power devices compared to other single dc-source inverters. Only nine active switches and two discrete diodes are utilized to obtain a nine-level waveform. Without the need for weighting factors, the proposed DB-MPC method tackles three control goals; current control, flying capacitors (FCs) stabilization and dc-link balance, which saves the laborious effort of adjusting the weighting factors in the traditional finite control set MPC (FCS-MPC) method. Moreover, an effective dc-link balancing scheme based on power flow control is proposed and integrated into the FCs control objective. To enhance the control robustness, an EKF-based estimator is designed to identify the system parameters online. In addition, the proposed DB-MPC scheme allows the considered inverter to continue operating with the generation of five levels in the failure condition of the four-quadrant switch, improving the fault tolerance of the inverter. The developed DB-MPC method is experimentally verified in steady-state and transient operation. To demonstrate the excellent performance of the presented DB-MPC scheme, experimental comparisons with other popular MPC methods are performed.

In this paper, a model-based maximum power point tracking (MPPT) technique is presented for a two-stage grid-connected photovoltaic (PV) system, where the loci of the maximum power points (MPPs) is specified accurately based on a new formulation. In this formulation, the effect of both irradiance and temperature is taken into consideration, whereas the irradiance is estimated to reduce the cost of the system and enhance its reliability. Furthermore, constant power generation (CPG) is integrated with the developed MPPT method to facilitate other power regulation schemes in the PV system. The proposed methodology is compared with the well-known perturb and observe (P&O) method for evaluation. Additionally, a modified version of the P&O is included in the comparison for better assessment. The effect of different partial shading conditions on the system’s performance is also investigated. The DC-link PI controller is replaced with a new adaptive DC-link controller to enhance the transient behavior of the PV system. Moreover, the suggested DC-link controller removes the DC offsets, which appear in case of gradient increase or decrease in the input PV power. In contrast to the conventional PI controller, which has poor performance at such circumstances. The active and reactive power exchange with the grid is managed using a computationally efficient finite-set model predictive control (FS-MPC) algorithm. Furthermore, switching frequency minimization is added as a secondary objective using a weighting factorless procedure. The grid-voltage sensors are eliminated and estimated using an extended Kalman filter (EKF). The overall control strategy is evaluated using experimental implementation, hardware-in-the-loop (HIL), and matlab/simulink.

This article presents a new high-efficiency nine-level T-type converter (9L-T2C) for grid-connected applications based on the three-level T-type converter (3L-T2C). The proposed 9L-T2C outperforms other common dc-link nine-level converters in terms of the required number of active switches and capacitors, flying capacitors (FCs) voltage ratings, and efficiency. Only ten power switches, eight gate drivers, and two FCs are required for each phase. Exploiting the available pole-redundant states, an FCs balancing algorithm is developed to stabilize the two FCs with one voltage sensor in steady-state and dynamic operation. Moreover, an effective balancing method is proposed for dc-link capacitors without the need for further redundant states and integrated into FCs balancing. The FCs and dc-link balance are integrated into the phase-disposition pulsewidth modulation (PD-PWM) method, eliminating the need for an additional controller. Considering the designed PD-PWM method, a mathematical analysis is performed to establish the relationship between the FCs size and the desired ripple. A comprehensive comparison with other converters is provided to demonstrate the merits and application areas of 9L-T2C. The operation of the proposed 9L-T2C with the capacitors’ balancing scheme is validated for stand-alone and grid-connected operation via simulation investigations and experimental setup.

This paper presents a low profile and low-cost patch antenna with dual circularly polarized (CP) capability in X-band at a canter frequency of 8.3 GHz. The dual-CP antenna is divided into three layers, composed of a parasitic square patch, a radiation square patch with four equal arms, and a 90◦ patch coupler. Two arms of the radiation patch are connected to the 90◦ hybrid coupler using two metalized vias. Right-handed circular polarization (RHCP) and left-handed circular polarization (LHCP) are achieved by exciting two different ports. To validate the proposed design, the prototype of the dual-CP antenna is fabricated and measured. Based on the measurement, the structure of the proposed antenna has an excellent circular-polarization purity of less than 3dB over the whole operational frequency bandwidth of the antenna (8GHz–8.47 GHz) with a wide 3-dB axial ratio (AR) beamwidth of 133◦ across the angular range from− 55◦ to+ 78◦ at 8.3 GHz.

A compact ultra-wideband printed ridge gap waveguide directional couplers for millimeter-wave applications are presented in this paper. A multi-layer coupling technique between two resonant patches is adopted to achieve a wider operating bandwidth with better amplitude and phase balance compared to single-layer technology. For this purpose, a systematic design procedure is deployed to achieve several coupling values in the range of 3–10 dB over a wide frequency bandwidth centered at 30 GHz. A 3-dB hybrid coupler is fabricated and measured, where a bandwidth of 12 GHz (about 38% fractional bandwidth) from 25 GHz to 37 GHz is achieved. In addition, the phase balance is 90o ± 5o over 38% fractional bandwidth with an amplitude balance of 3.4 ± 0.5 dB over a 26.5% centered at 30 GHz. The proposed couplers with superior characteristics such as compactness, low loss, and low dispersion are considered a good candidate for millimeter-wave applications such as the fifth-generation (5G) wireless communications.

Graphene-based microwave devices have enabled reconfigurability, thus paving the way to the realization of flexible wireless terahertz systems with featured performances. Despite great progress in the development of graphene-based terahertz devices in the literature, high insertion loss and wide tunable range are still significant challenges at such high frequencies. In this work, we introduce the use of graphene to implement a reconfigurable printed ridge gap waveguide (RPRGW) structure over the terahertz frequency range for the first time. This guiding structure is suitable for both millimeter and terahertz wave applications due to its supporting quasi-TEM mode, which exhibits low dispersion compared to other traditional guiding structures. The presented solution is featured with low loss as the signal propagates in a lossless air gap, which is separated from the lossy graphene elements responsible for the reconfigurable behavior. In addition, this guiding structure is deployed to implement a tunable RPPGW power divider as an application example for the proposed structure.