Average Total Efficiency Research Articles

Assessing the nutrient removal performance from rice-crayfish paddy fields by an ecological ditch-wetland system

Agricultural drainage from catchments significantly impacts aquatic ecosystems due to high nitrogen and phosphorus concentrations in runoff. While original ecological ditches and wetlands have demonstrated effectiveness in nutrient load removal, the overall impact of an ecological ditch-wetland system (EDWS) on agricultural nutrient removal has received limited attention. This study conducted a field experiment to investigate the physicochemical conditions and nutrient removal efficiency of an EDWS for purifying nutrient discharge from rice-crayfish paddy fields. Variations in water temperature (WT), dissolved oxygen (DO), pH, and total suspended solids (TSS) within the EDWS were assessed. Nutrient concentrations—including total nitrogen (TN), ammonium nitrogen (NH4-N), nitrate nitrogen (NO3-N), total phosphorus (TP), and soluble reactive phosphorus (SRP)—were monitored from the tillering to the ripening stage of the rice growth cycle. The evaluation of nutrient removal efficiencies in the EDWS revealed that ecological ditches exhibited higher removal efficiencies compared to wetlands. The average total removal efficiencies for TN, NH4-N, NO3-N, TP, and SRP were 37.50 %, 39.38 %, 38.62 %, 37.94 %, and 39.51 %, respectively, with peak removal efficiencies observed at specific growth stages of the rice crop. Furthermore, the study explored the influence of hydraulic retention time on nutrient removal efficiency in the EDWS, indicating higher nutrient discharge removal efficiencies under low water discharge rates. Linear regression analysis identified water discharge, influent nutrient loads, and TSS as significant factors affecting nutrient removal efficiency in the EDWS. This study provides valuable insights into the effectiveness of EDWS in purifying nutrient discharge from rice-crayfish paddy fields, highlighting their potential as sustainable solutions for nutrient management in agricultural landscapes.

Hybrid solar-biomass residential micro – Combined Heat and Power systems driven by the Partially Evaporating Organic Rankine Cycle – A case study in Southern Europe

In this study, a novel hybrid solar-biomass residential micro – Combined Heat and Power system driven by the Partially Evaporating Organic Rankine Cycle is proposed and its operation is simulated, by applying an in-house numerical model. The simulation tool is applied for a test case in Athens, Greece, where the micro-CHP system operates to cover the annual energy demand of a multi-family building. The proposed cogeneration unit covers 97.10 % and 25.85 % of the modeled building’s annual Space Heating and electricity demand, respectively, by using renewable energy sources. The annual average total energy and exergy efficiencies are equal to 53.33 %, and 10.35 %, respectively, while the power cycle can achieve thermal efficiencies as high as 9.73 %. Competitive Levelized Cost of Electricity (0.072–0.133 €/kWhel), and Levelized Cost of Heat (0.036–0.067 €/kWhth) values are estimated, with a PayBack Period between 5.17 and 9.64 years. The environmental impact of the proposed hybrid micro-CHP is anticipated to be significant, rising to 46.25 kWh of Primary Energy Savings, and 31.22 kg CO2-eq. reduction in carbon emissions per m2 of residence annually.

Childhood Adversity and Adolescent Epigenetic Age Acceleration: The Role of Adolescent Sleep Health.

We investigated how a dimension of early life adversity (ELA) capturing threat in the home relates to later epigenetic age acceleration in adolescence through sleep (duration, efficiency, and timing), to empirically test theoretical models suggesting the importance of sleep as a key mechanism linking ELA with poor health outcomes, and to expand the limited literature on sleep and epigenetic aging among youth. We utilized data from 861 participants from the Future of Families and Child Wellbeing Study (FFCWS) who participated in the actigraphy sub study at age 15. Sleep variables used were average total sleep time (TST), sleep efficiency (SE), and sleep onset timing. Home threat was determined at ages 3, 5, and 9 from parent reports on the Child Conflict Tactics Scale (CTS-PC), and epigenetic aging was measured through DNA methylation analyses of saliva samples collected at age 15. Higher levels of childhood home threat exposure were associated with less adolescent TST, lower SE, and later sleep onset timing. Adolescent SE and timing were associated with a faster pace of aging and epigenetic age acceleration. Sleep efficiency and timing mediated the link between childhood home threat exposure and adolescent epigenetic aging. Epigenetic embedding of childhood threat exposure in the home may occur through adversity-related sleep disturbances in adolescence. Findings warrant greater attention to pediatric sleep health in theoretical models of biological embedding of adversity and point to the examination of improving sleep health as a potential way to prevent adversity-related epigenetic age acceleration.

Occurrence, Fate, and Removal of Selected Antibiotics in Advanced Biological Urban Wastewater Treatment Plant

Wastewater treatment plants (WWTPs) are considered as one of the most important point sources for releasing antibiotics into the natural environment. In this study, the occurrence, fate, and removal of three antibiotics, ciprofloxacin (CIP), sulfamethoxazole (SMX), and azithromycin (AZI), belong to quinolone, sulfonamide, and macrolide groups, respectively were investigated seasonally in a large-scale urban WWTP. While the occurrence concentrations of the investigated antibiotics in raw wastewater were found between about 0.26 and 0.73 μg/L in the summer season, it was determined in the range of approximately 0.41 and 4.6 μg/L in the winter season. Although the removal efficiencies obtained for antibiotics in the pre-treatment stage of the studied advanced biological WWTP were not very high, the most treated compound in the pre-treatment stage was determined as CIP (up to 23.8%). Total removal efficiencies of the investigated antibiotics in the WWTP varied mainly based on the biological treatment stage of the WWTP. At the same time, removal efficiencies of the antibiotics obtained in the biological treatment also changed considerably depending on the seasons. Among all the investigated antibiotic compounds, it was determined that AZI was the compound that was least affected by the seasons in terms of the total removal efficiency obtained in WWTP. According to the annual average total removal efficiencies, it was determined that SMX (25.7%), CIP (71.3%), and AZI (89.2%) were treated poorly, moderately, and highly in WWTP, respectively. However, advanced biological WWTP was determined to be insufficient for the complete removal of total antibiotics.

Drying of Nettle Using Concentrated Air Collector and Concentrated Photovoltaic Thermal Supported Drying System and Modeling with Machine Learning

This study examines the performance of a solar assisted drying system in the nettle drying process. The drying process works by using thermal energy obtained from solar air collectors and PV modules. The experimental were carried out in October 2022, and the room temperature, total efficiency and moisture content parameters were investigated. The data obtained from the drying system were modelled using machine learning algorithms such as artificial neural networks (ANN), support vector machines (SVM), and gradient boosting decision trees (GBDT). The average thermal energy transferred to the drying cabin was calculated as 154 W, with 77% of this energy was obtained from the air collector and the remaining 23% from the PV module. The stinging nettle was dried from an initial moisture content of 11.18 g water/g dry matter to a final moisture content of 1.18 g water/g dry matter. The average total efficiency of the drying system was found to be 16.8%. Additionally, the results show that the SVM algorithm exhibits the best performance in estimating important parameters such as chamber temperature, moisture content, and total efficiency. Especially in total efficiency prediction. The SVM algorithm has a significant advantage over other algorithms. As a result, it was concluded that the SVM algorithm can be used effectively utilized in solar energy-supported drying systems and can be a precious choice for the optimization of the drying process.

Research and application of bag filter system for railway ballast bed coal suction vehicles: An optimization and application study.

The current bag filter system used by railway ballast bed coal suction vehicles for cleaning coal dust from railway tunnels has low operational efficiency and generates significant volumes of dust. This paper describes a simulation test unit designed to enhance the dust removal performance in railway tunnels. The flow field inside the simulation test unit is investigated under different operating conditions through numerical simulations, and the variations in air volume and working resistance, total dust collection efficiency, and optimal operating parameters of a pulse cleaning system are identified through a series of experiments. The numerical results show that the pulse cleaning system does not significantly affect the uniformity of the flow field distribution at the bottom of the filter cartridge during the process of operation. The experimental research indicates that the simulation test unit satisfies the design requirements, achieving an average total dust removal efficiency of 99.93%. A field application shows that the total dust mass concentration at the operator position can be reduced from 335.8 mg∙m-3 to 4.2 mg∙m-3, effectively improving the operating environment within the tunnel.

Heat storage and release characteristics of a prototype CaCO3/CaO thermochemical energy storage system based on a novel fluidized bed solar reactor

CaCO3/CaO thermochemical energy storage (TCES) system has a high heat storage density (1780 kJ/kg) along with high heat storage and release temperature (650–850 °C), which can be applied to concentrated solar power (CSP) technology utilizing CO2 Brayton cycles to improve power generation efficiency. There are several problems to be urgently resolved in current CaCO3/CaO solar calciners, such as poor heat and mass transfer and low thermochemical efficiency. This paper proposed a prototype CaCO3/CaO TCES system based on a novel fluidized bed solar reactor, which has a serrated arc surface in alignment with the direction of the incident solar rays to receive concentrated solar energy. The natural limestone particles were used as the reactive particles. The effects of operating modes (intermittent/continuous), initial mass of reactive particles, and initial carbonation temperature Tcar,initial on the heat storage and release characteristics of the TCES system were experimentally explored. During the carbonation reaction stage, the effective carbonation degrees in the continuous mode were generally higher than in the intermittent mode under the experimental conditions and declined at a slower rate. The reactive particles were recovered from the reactor for microstructural characterization after completing the experiments, high-temperature particle agglomeration and pore structure clogging were directly responsible for the decrease of the effective carbonation degree. In the continuous mode, the average thermochemical and total thermal efficiencies of 24.7 % and 53.5 % were obtained in the 1st calcination reaction, respectively, which represents significant advantages over other CaCO3/CaO solar calciners. The novel fluidized bed reactor demonstrated excellent fluidization in the experiments and did not exhibit mechanical deformation after multiple experiments under non-uniform concentrated radiation provided by an 84 kWe high-flux solar simulator. Overall, this paper provides a successful gas-solid reactor design to be coupled with CSP technology.

Effects of shift work on sleep quality and cardiovascular function in Taiwanese police officers

ABSTRACT This study aimed to investigate the effects of shift work on sleep quality, cardiovascular function, and physical activity (PA) levels in Taiwanese police officers. Twenty-one male police officers aged 26.9 ± 4.1 years old located in Taipei voluntarily participated in this study. The participants completed the resting heart rate (HR) and hemodynamic variables (e.g. blood pressure, BP) before and after day-time (DTW) and night-time (NTW) shift work phases (5 working days and 2 resting days for each phase). Additionally, an actigraphy was administered to measure PA and sleep patterns in the last 3 working days. The average total sleep time and sleep efficiency were 278.5 ± 79. 6 min and 72.9 ± 10%, respectively, in the NTW phases, which were significantly lower than that in the DTW phases. A comparison of the PA characteristics between the two phases revealed that a lower proportion of moderate-vigorous PA (1.2 ± 0.8%) and a greater proportion of sedentary behaviour PA (74.8 ± 6.4%) was found in the NTW phases. The results of hemodynamic measures demonstrated that the police officers have significantly elevated systolic BP by 3.3% and diastolic BP by 3.9% after the NTW phases. Furthermore, the NTW phases exhibited a significantly higher percentage change ratio of systolic BP and diastolic BP compared to the DTW phases. Compared with the DTW phases, the NTW phase was significantly more likely to report higher decreasing parasympathetic-related HR variability with a range of −5.9% to −7.8%. In conclusion, night-time shift work resulted in negative physiological changes leading to adverse effects on the health and well-being of Taiwanese police officers.

A multidimensional analysis of corporate governance mechanisms and their impact on sustainable economic development: A case study of Ghana’s financial sector

Efficiency remains pivotal to the banking sector, serving as a linchpin for resource allocation and competitive prowess. This study delves into the intricate dynamics between corporate governance and banking efficiency in Ghana, with an analytical lens on cost efficiency (CE) and total efficiency (TE). Utilizing Data Envelopment Analysis (DEA), our investigation spans over a decade (2008–2019) and encompasses a data set of 23 Ghanaian banks.The study findings unveils that rigorous corporate governance mechanisms, as quantified by the Corporate Governance Index (CGI), exert a salutary influence on both cost and total efficiencies. Moreover, a well-defined Risk Management Index (RMI) positively correlates with cost efficiency, albeit without a substantial impact on total efficiency. Conversely, the study identifies a counterintuitive effect: the current make-up of supervisory boards, as gauged by the Supervisory Board Index (SBI), inversely impacts both efficiency metrics, signaling sub-optimal governance structures.Significantly, the research also highlights a pressing concern: the average total efficiency of Ghanaian banks lags behind the global benchmarks prescribed by the World Bank. This discrepancy underscores an exigency for efficiency optimization within the sector.The study thereby offers invaluable insights for multiple stakeholders—including regulatory bodies, investment communities, and policymakers—by delineating the governance variables that can enhance or impede banking efficiency. It also identifies actionable avenues for improvement, specifically in the realms of risk management and board composition, with the potential to catalyze a transformation in Ghana's banking landscape.

Numerical analysis and deep learning algorithm for photovoltaic-thermal systems using various nanofluids and volume fractions at Riyadh, Saudi Arabia

Conventional photovoltaic (PV) systems have elevated temperatures in the hot climate of Riyadh, resulting in reduced electrical power generation. Therefore, nanofluids are employed in photovoltaic-thermal (PV-T) systems to absorb the self-generated heat that limits efficient operation. In addition, developing deep learning models would help improve the optimization and control of the proposed system. This study's primary goal is to numerically examine a PV-T system under the influence of using various nanofluids with varying volume fractions in the hot climate of Riyadh and to develop time-series deep learning algorithms based on the findings in this examination to predict the PV-T system's potential. A mathematical model to investigate the PV-T panel performance under various volume concentrations and nanofluids is proposed. The generated data from the different nanofluids is deployed to train a deep learning model, which is convolutional neural networks integrated with two layers of long short-term memory (CNN-LSTM), in order to predict the PV-T panel temperature. According to the investigation's findings, the best PV-T coolant is CuO nanofluid at 4 % volume concentration. Utilizing the aforementioned nanofluid can deliver an enhancement in the average daytime PV-T panel temperature, electrical, thermal, and total exergy efficiency by 34.5 °C, 16.7 %, 79.2 %, and 18.07 %, respectively. The developed deep learning algorithms were evaluated using the mean absolute error (MAE) and coefficient of determination (R2) and scored 0.18–0.35 and 97.5–98.75 %, respectively.

Seasonal dynamic modeling and simulation of solar thermal membrane desalination system for sustainable freshwater production: a case study of Tanta, Egypt

AbstractMembrane distillation (MD) is an effective process for desalinating seawater, combining the merits of both thermal and membrane distillation. In this context, the sizing methodologies and optimization strategies are developed from the balance of the system’s energy demand. Therefore, accurate numerical modeling of the heat transfer and thermodynamic behavior of the MD systems is crucial for the optimal design of solar-based MD systems. The interest in utilizing solar thermal heating techniques for feed water heating in MD systems is increasing worldwide for sustainable freshwater production and lowering energy consumption. Hence, in this research, a coupled analytical modeling based on heat transfer, mass transport, and thermodynamic analysis is created to dynamically simulate a solar direct contact membrane distillation system (SDCMDS) driven by vacuumed tubes solar collectors (VTSCs) to analyze its performance, under real weather of Tanta, Egypt. The influences of the solar collecting area on the performances of the proposed SDCMDS for augmenting the freshwater production of the SDCMDS are studied. Four cases of the proposed SDCMDS are investigated: two identical VTSCs of 1.80 m2 each unit in summer (Case I), two identical VTSCs in winter (Case II), four identical VTSCs in summer (Case III), and four identical VTSCs in winter (Case IV). The results show that the utilization of four VTSCs connected in series significantly improved the feed seawater temperature range from 30.0 to 70.5 °C compared to a feed temperature range of 30.0–49.5 was achievable by utilizing only two VTSCs. Moreover, the daily averaged permeate flux were 2.21, 1.29, 3.41, and 2.07 L/day per m2 of solar harvesting area with daily cumulative distilled water yield of 7.48, 4.60, 23.04, and 14.78 L/day for Cases I, II, III, and IV, respectively, at a saline flowrate of 0.20 kg/s. The daily average total efficiency of the SDCMDS was obtained to be 14.70%, 12.50%, 24.95%, and 22.50% for Cases I, II, III, and IV, respectively.

P077 Associations of sex, sleep, and circadian rhythms with performance in elite Australian Rules footballers

Abstract Introduction Poor sleep and circadian misalignment are associated with poorer performance. In elite Australian Rules football (ARF), both sex and professionalism could alter or exacerbate these associations. This study provides preliminary insights on how the relationships of sleep and circadian alignment with cognitive performance differ between male full-professional and female semi-professional elite ARF athletes. Methods Participants were 72 elite ARF athletes (42% female; M-age = 24.1±4.4 years). During pre-season, participants completed two weeks of sleep/wake monitoring via actigraphy, and a circadian phase assessment (dim light melatonin onset; DLMO) after one week. Cognitive performance testing (psychomotor vigilance task, PVT; and the balloon analogue risk task; BART) was conducted five times throughout this period. Results Preliminary findings suggest average total sleep time and sleep efficiency, sleep regularity, DLMO, and phase angle (interval between average sleep onset and DLMO) did not predict reaction time on the PVT, nor did sex moderate these relationships. After controlling for sex, longer sleepers demonstrated greater risk taking on the BART. Only among male athletes did larger angles predict greater risk taking. Discussion Elite ARF athletes, regardless of sex, sleep, or circadian alignment, have similar reaction times. Risk taking is greater among longer sleepers and in male athletes experiencing relatively delayed circadian phases. Where risk-taking has negative implications (e.g., injury and sporting errors), these findings identify at-risk groups. Few sex-specific findings may suggest that the semi-professional status of female ARF (and associated lifestyle factors such as scheduling and income) is not altering elite performance in controlled settings.

Compact wideband MIMO antenna with fragmented patches for 5G mobile terminals

AbstractA compact wideband MIMO antenna obtained by breaking up an intact rectangular patch into a 2 × 5 small patch array with connected strips is proposed for 5G mobile terminals. The diagonal small patches are connected with the metal strips respectively, so as to constitute an interleaved double branch composed of a main branch and a parasitic branch, thus achieving compactness. The main branch fed by two ports operates at 4.5 GHz, and the parasitic branch coupled by the main branch achieves a lower resonant frequency of 3.35 GHz, thus widening the bandwidth. The small patches in the middle are connected to the ground to improve the isolation. A short length of 21.5 mm (about 0.24 wavelength of the lower‐edge frequency) of the proposed antenna pair is realized. Besides, an eight‐element MIMO antenna is designed and fabricated. Measured results show the reflection coefficients are lower than −6 dB, and the transmission coefficients between every two ports are lower than −10 dB in the 5G N77/N78/N79 bands (3.3–5.0 GHz). The average total efficiencies are 70.4% and 63.8% for antenna 1 and antenna 2, respectively. The ECCs are lower than 0.15.

A Wideband and Dual-Polarized Millimeter-Wave Antenna With Single-Layered Geometry and Low Profile

This paper reports the design of a novel wideband and dual-polarized millimeter-wave antenna with single-layered geometry and low profile. The antenna is mainly composed of a square patch and two inverted-F antennas (IFAs), and they are located in the same substrate layer. Wide bandwidth has been achieved by taking advantage of the dual resonances generated by patch and IFA modes. The antenna feed is constructed by a through pin connecting to the corresponding IFA and, therefore, leading to a dual-polarized antenna performance as well as a single-layered antenna structure with a low profile of 0.07 λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> . An L-shaped metal strip has been introduced in order to improve the port isolation. The design concept has been verified by prototyping and testing a 2×2 array antenna in the Ka band. It has been demonstrated that the proposed 2×2 array antenna has a 21% bandwidth with average total efficiency higher than 72% and realized gain up to 11.1 dBi.

Preparation, characterization, and in vivo evaluation of glycyrrhetinic acid-mediated nano-drug delivery system co-loaded with syringopicroside and hydroxytyrosol.

This study aimed to create a glycyrrhetinic acid (GA)-mediated, multi-component, self-assembled nano-drug delivery system co-loaded with syringopicroside (S) and hydroxytyrosol (H) obtained from Syringa Linn by synthesizing a GA-polyethylene glycol-poly (lactic acid-co-glycolic acid) (GPP) nanoparticle delivery carrier to actively target the liver. The nanoparticles were optimized using the central composite design. Nanoparticle characterization, cytotoxicity, pharmacodynamics, and tissue distribution study were performed. The optimized SH-GPP nanoparticle was a white solid powder, which was safe and non-toxic. The particle size and Zeta potential of the nanoparticles were 101.5 ± 3.18nm and -23.3 ± 0.82mV, respectively. The polydispersity index value (PDI) was 0.190 ± 0.005; the particle size distribution was comparatively uniform. The average total encapsulation efficiency of the optimized SH-GPP nanoparticle was 50.26% ± 1.29%, and drug loading was 15.47% ± 0.39%. After S and H were arranged into nanoparticles, the proliferation inhibition of HepG2.2.15 cells was improved, and the aim of drug-loaded synergism between GPP and SH was achieved. The GA-mediated nanoparticles were better targeted, were retained longer in vivo, and had higher concentrations in the liver than the unmodified nanoparticles. These nanoparticles have the potential to be a new effective anti-hepatitis B treatment and have great research potential in clinical treatment.

Evaluating the resource recovery efficiency of garbage removal and disposal in Taiwan.

All countries recognize the importance of enhancing circular resource utilization and promoting zero waste in order to achieve a circular economy. This study focuses on 22 counties (cities) in Taiwan and analyses the relationship between changes in resource recovery efficiency and productivity over an 8-year period (2011-2018) using the super efficiency directional distance function and total factor productivity. The results indicate that the average total efficiency of resource recovery in the 22 counties (cities) is 1.3951, with 17 counties (cities) exceeding 1. The average gross productivity of resource recovery is 1.0417, and only four counties have a gross productivity of less than 1. Despite having more administrative resources, municipalities directly under the central government have a slightly lower average total efficiency of resource recovery (1.1464) than non-municipalities (1.4885). To improve efficiency, the government should allocate resources rationally and upgrade technology. The study's findings can serve as a reference for the 22 counties (cities) in Taiwan and provide guidance for municipal governments worldwide in developing policies related to resource recovery.

Mechanically Controlled, Wide-Angle Scanning, Series-Fed Antenna Array With Low Profile for High-Power Radar Systems

This paper presents the design and implementation of a mechanically-controlled, series-fed antenna array featuring wide-angle beamsteering at the X-band. A theoretical model of a series-fed array, including phase shifters inserted between consecutive elements, is initially developed to derive design rules and gain insight into crucial performance trade-offs. Subsequently, a mechanically-controlled, reflection-type phase shifter consisting of a branch line coupler and two Pi-network reflective loads is presented. A movable metallic overlay tunes the impedance of the reflective loads, thus effectively modifying the output phase. While requiring a minimal linear displacement of only 0.06λ0, this topology provides a maximum phase shift of 300° with an average insertion loss of 1 dB and is exploited for synthesizing a series-fed patch array. Based on simulations and measurements, the proposed antenna offers an almost constant realized gain of about 15 dBi within a wide scanning range of ±50°, and the side lobe level is better than -12 dB. The average total efficiency is 50%, and the cross-polarization levels are at least 11 dB below the maximum realized gain. The main weaknesses are the narrow bandwidth of 2.5% and the slight beam squint as the frequency varies. The proposed design is ideal for radars due to its excellent performance and high power-handling capability.

Performance analysis and structure optimization for concentrated photovoltaic-phase change material-thermoelectric system in space conditions

High-efficient thermal management is urgently needed for concentrated photovoltaic-thermoelectric hybrid system due to the high heat flux. In present paper, a three-dimensional model for the hybrid system in outer space conditions was established by coupling phase change temperature control and radiation heat sink technologies to find the propriate thermal management scheme. Firstly, the three shortcomings in the typical hybrid system were proposed and their adverse effects on efficiency were elucidated. Then, a heat transfer pillar for temperature control unit and a newly designed circular fins for heat sink were designed. The effects of structure parameters on power generation performance were investigated, and the interaction between temperature control unit and heat sink were discussed. The results show that the hybrid systems with the newly designed heat transfer pillar and circular fins have higher efficiency. After that, a united structure optimization by artificial neural network-multi-objective genetic algorithm was performed to solve the interaction and to balance the electrical efficiency and power density of hybrid system. The comprehensive power generation performance of hybrid system can be further improved after the optimization. The system with PCM thickness dPCM = 6.33 mm, heat transfer pillar width a = 18.19 mm, fin length L = 49.99 mm and fin radius R = 50 mm, has the maximum average total efficiency (31.83%, 2.98% higher than the typical system); the system with dPCM = 3.02 mm, a = 10.05 mm, L = 47.03 mm and R = 25.86 mm, has the maximum average power density (36.97 W/kg, 15.78% higher than the typical system).

N ASSESSING THE EFFECTIVENESS OF HYBRID SOLAR COLLECTORS SCHEME INIRAQ'S ENVIRONMENT

An evaluation of the performance of the Iraqi environments in terms of electrical, thermal and exergy efficiency is introduced in this study. The research is carried out in May 2022, in the Baghdad metropolis. The extraction process of heat from the photovoltaic units which arises from the coolant liquid mass flow rate deem as an essential point. The experimental studies were implemented by absorbing heat energy behind from the photovoltaic cell's surface in insulated conditions and using a cooled water unit. The results indicated that at a mass inflow rate of 0.2 kg/sec, the maximum average total efficiency of the system was recorded 22%. As a result, it is advised that to reduce the payback interval, it is possible to design efficient solar photovoltaic–thermal systems to promote the whole system's efficiency and lower the payback interval.

A Novel 4× 4 MIMO Antenna Decoupled by T-Shaped Dummy Antenna with High Robustness for 5G Mobile Devices

It is challenging to design a compact antenna pair with isolation better than 20 db and with robustness to antenna position. In this paper, a T-shaped dummy antenna is adopted to decouple the tightly arranged antenna pair for 5G mobile devices. Working in the 3.8 GHz of N77 band, the proposed antenna pair is with an impedance bandwidth of 280 MHz. Isolation of the proposed antenna pair is enhanced from 13 db to 30 db by adding the T-shaped dummy antenna, and it is with high robustness even though the antenna position is altered. The calculation process of the loading requirement of T-shaped dummy antenna is shown. By duplicating the proposed antenna pair, a 4×4 MIMO antenna with high isolation is proposed. The measured results show the MIMO antenna with isolation better than 31 db, and the average total efficiency is about 49%, and the Envelope Correlation Coefficient (ECC) is lower than 0.05 in the -6 db pass band. To the best of the authors’ knowledge, compared to most of the reported antenna pairs, the proposed 4××4 MIMO antenna is with the highest isolation while keeping a compact size.