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Effects of Strength Training Program and Infrared Thermography in Soccer Athletes Injuries
摘要： The purpose of this investigation was to examine the effects of a periodized strength training program and the use of infrared thermography (IRT) in injuries mapping in under 20-year-old (U-20) soccer players. In this study, 26 professional soccer players participated in strength training (ST) twice a week and were tested with IRT consistently across the 1-year. Strength, vertical jump, heat differences and injuries were tracked and analyzed. Results: 69 injuries occurred during 12 months of tracking; most identi?ed injuries were: contusions, sprains, strains to the thigh (n = 16), ankle (n = 15) and knee (n = 12). Differences (>7 ?C) in IRT patterns were noted among injured and non-injured athletes. Signi?cant improvements in strength (p < 0.005) were found for vertical jump, bench press, front lat pull down, shoulder press, leg press, leg curl and squat. Number of injuries decreased from 23 (33.3%) to 14 (20.3%) when early year rates were compared to late year (p < 0.005). Combined ST and IRT represent useful strategies for reducing injuries among U-20 soccer players.
关键词： periodization,performance,contusions,treatment outcome
更新于2025-09-23 15:21:21
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Statistical evaluation of corner detectors: does the statistical test have an effect?
摘要： This study explores the use of several non-parametric statistical tests for evaluating the performances of computer vision algorithms, specifically corner detectors, as a more reliable alternative to the graphical approaches that have been commonly employed to date. Using synthetic images carrying corners of different internal angles and orientations and a carefully designed testing framework, a ranking of the performances of corner detectors was established. It was found that Harris & Stephens and SUSAN out-performed more modern detectors. These are one of the few examples where evaluation of vision operators independent of the application has predicted performance in a real-world problem. A similar exercise on real images of the same patterns produced similar results and the findings of a real-world application that uses corners to identify signage were also consistent. Together, all of the tests considered essentially perform pairwise comparisons of performance, so when many algorithms are involved it is important to take account of the potential for type I statistical errors. Several approaches were evaluated and none were found to affect the conclusions.
关键词： performance evaluation,computer vision algorithms,corner detectors,non-parametric statistical tests
更新于2025-09-23 15:21:21
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Effects of vacancy defects location on thermal conductivity of silicon nanowire: a molecular dynamics study
摘要： The improvement of thermoelectric ?gure of merit of silicon nanowire (SiNW) can be achieved by lowering its thermal conductivity. In this work, non-equilibrium molecular dynamics method was used to demonstrate that the thermal conductivity of bulk silicon crystal is drastically reduced when it is crafted as SiNW and that it can be reduced remarkably by including vacancy defects. It has been found that ‘centre vacancy defect’ contributes much more in reducing the thermal conductance than ‘surface vacancy defect’. The lowest thermal conductivity that occurs is about 52.1% of that of pristine SiNW, when 2% vacancy defect is introduced in the nanowire. The vibrational density of states analysis was performed to understand the nature of this reduction and it has been found that the various boundary scatterings of phonon signi?cantly reduce the thermal conductivity. Also, larger mass difference due to voids induces smaller thermal conductivity values. These results indicate that the inclusion of vacancy defects can enhance the thermoelectric performance of SiNWs.
关键词： molecular dynamics,silicon nanowire,thermoelectric performance,thermal conductivity,vacancy defects
更新于2025-09-23 15:21:21
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[IEEE 2018 4th International Conference for Convergence in Technology (I2CT) - Mangalore, India (2018.10.27-2018.10.28)] 2018 4th International Conference for Convergence in Technology (I2CT) - Performance Analysis of a 48 kWp Grid connected Rooftop Photovoltaic System
摘要： The dropping market prices of power generated from solar photovoltaics is making it an attractive option for decentralized power in the form of rooftop and ground mounted systems. In the present scenario, the presence of solar photovoltaics in the energy mix is continuously increasing. Thus, it is important to monitor the performance of these systems to identify deviations from expected performance and to maintain higher system efficiency. This paper presents the details of performance analysis study conducted on a 48 kWp rooftop solar PV system located in the Northern India monitored over a 1 year period. The actual measured values of system performance parameters are compared to results obtained from simulating the systems using the PVsyst software. The values estimated using PVsyst for performance ratio and yearly average of system efficiency are 82% and 13.67%. The yearly average value of CUF estimated is 16.14%.The results of this study can aid in providing a glimpse into the operation of solar PV systems operating in the North Indian climate and can help in carrying out future comparative studies. The results obtained in the current study are also compared with the performance parameters of other plants operating in India.
关键词： capacity utilization factor,PVsyst,Performance analysis,performance ratio
更新于2025-09-23 15:21:01
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Photovoltaic Degradation Rate Affected by Different Weather Conditions: A Case Study Based on PV Systems in the UK and Australia
摘要： This article presents the analysis of degradation rate over 10 years (2008 to 2017) for six different photovoltaic (PV) sites located in the United Kingdom (mainly affected by cold weather conditions) and Australia (PV affected by hot weather conditions). The analysis of the degradation rate was carried out using the year-on-year (YOY) degradation technique. It was found that the degradation rate in the UK systems varies from ?1.05% and ?1.16%/year. Whereas a higher degradation ranging from ?1.35% to ?1.46%/year is observed for the PV systems installed in Australia. Additionally, it was found that in the Australian PV systems multiple faulty PV bypass diodes are present due to the rapid change in the ambient temperature and uneven solar irradiance levels influencing the PV modules. However, in cold weather conditions (such as in the Northern UK) none of the bypass diodes were damaged over the considered PV exposure period. Furthermore, the number of PV hot spots have also been observed, where it was found that in the UK-based PV systems the number of hot spotted PV modules are less than those found in the Australian systems. Finally, the analysis of the monthly performance ratio (PR) was calculated. It was found that the mean monthly PR is equal to 88.81% and 86.35% for PV systems installed in the UK and Australia, respectively.
关键词： performance analysis,photovoltaic systems,performance ratio,degradation,hot-spots
更新于2025-09-23 15:21:01
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Controlled Synthesis of Coral-Like CuO Dendrites with Enhanced Photocatalytic Performance
摘要： In this work, coral-like CuO dendrites were successfully synthesized by a solvothermal method in the mixed solvent of distilled water and ethanol with assistance of dodecyl trimethyl ammonium bromide (DTAB). The products were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), energy dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and Brunauer-Emmett-Teller (BET) analysis techniques, to investigate their structure and morphology. The coral-like CuO dendrites were about 1 μm in length, with many dendrites pointing to a common center. The influence of experimental conditions on morphology, such as volume ratio of water to ethanol, surfactant DTAB and molar ratio of Na2CO3 and Cu(CH3COO)2, was also discussed. Time-dependent experiment was carried out to explore the formation mechanism while a “particle-sheet-dendrite (PSD)” mechanism was proposed to explain the growth process. The as-prepared CuO dendrites were used to degrade methylene blue (MB) under visible light irradiation in the presence of H2O2, where over 98% of methylene blue (MB) was degraded in 1 h. Results from the study demonstrated that the as-prepared coral-like CuO dendrites exhibited enhanced photocatalytic performance and excellent stability and reusability.
关键词： Photocatalytic Performance,Solvothermal Method,Coral-Like CuO Dendrites
更新于2025-09-23 15:21:01
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Performance modeling and analysis of high-concentration multi-junction photovoltaics using advanced hybrid cooling systems
摘要： This paper presents the performance modeling and analysis of the high-concentration multi-junction photovoltaic cells, using either constant-width one-section or two-stepwise microchannels-jet impingement hybrid cooling system. The performance simulation and analysis of the cells are conducted using a three dimensional-Computational Fluid Dynamics program for various operating parameters, including water flow rate (100–1300 mL/min.), inlet water temperature (10–80 °C), and heat flux (10–90 W/cm2 corresponding to concentration ratios of 250–2250). The thermal and electrical characteristics of the cells are correlated in dimensionless form as functions of the direct normal irradiance and the operating and geometrical parameters of the hybrid cooling systems. The developed high-quality explicit performance model correlations assist in the design, performance prediction, and selection of operation strategy of photovoltaic cells. The results indicated that the generated and net output power is directly proportional to the applied heat flux (concentration ratio) and inversely proportional to the inlet water temperature. Temperature uniformity of the photovoltaic base enhances with the water flow rate, deteriorates with heat flux, and less affected by the inlet temperature, particularly for the two-sections cooling system. The pumping power increases with water flow rate and decreases as both inlet temperature or heat flux increases. Heat transfer characteristics enhance significantly with water flow rate, moderately with inlet water temperature and slightly with heat flux.
关键词： Photovoltaic performance modeling,High-concentration multi-junction photovoltaic,Operating parameters,Microchannels heat sink,Electrical power correlations
更新于2025-09-23 15:21:01
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[IEEE 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Chicago, IL, USA (2019.6.16-2019.6.21)] 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Inorganic cesium-lead mixed halide perovskite p-i-n solar cells deposited using layer-by-layer vacuum deposition technique
摘要： Heterogeneous cellular networks (HetCNets) offer a promising solution to cope with the current cellular coverage crunch. Due to the large transmit power disparity, while following maximum power received (MPR) association scheme, a larger number of users are associated with macro-cell BS (MBS) than small-cell BSs (SBSs). Therefore, an imbalance load arrangement takes place across the HetCNets. Hence, using cell range expansion-based cell association, we can balance the load across the congested MBS. However, using MPR association scheme, users’ of?oading leads to two challenges: 1) macro-cell interference, in which the MBS interferes with the of?oaded users, and 2) coupled downlink-uplink cell association, in which a random user associates with a single tier’s base station (BS) both in uplink (UL) and downlink (DL) directions. This paper aims to address these problems while considering a two-tier scenario consisting of small-cell and macro-cell tiers. For the MBS interference mitigation, we employ a reverse frequency allocation (RFA) scheme. Besides coupled DL–UL association (Co-DUA), this paper also highlights the notion of decoupled DL–UL association (De-DUA). In De-DUA, a random user associates with two different tiers’ BSs, i.e., with one tier’s BS in the DL direction and with the other tier’s BS in the UL direction. Our results illustrate that, in comparison with the Co-DUA, De-DUA with RFA employment achieves a better coverage performance.
关键词： small-cell BSs,decoupled downlink-uplink association,Heterogeneous cellular networks,coverage performance,reverse frequency allocation
更新于2025-09-23 15:21:01
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Day-ahead photovoltaic power production forecasting methodology based on machine learning and statistical post-processing
摘要： A main challenge towards ensuring large-scale and seamless integration of photovoltaic systems is to improve the accuracy of energy yield forecasts, especially in grid areas of high photovoltaic shares. The scope of this paper is to address this issue by presenting a uni?ed methodology for hourly-averaged day-ahead photovoltaic power forecasts with improved accuracy, based on data-driven machine learning techniques and statistical post-processing. More speci?cally, the proposed forecasting methodology framework comprised of a data quality stage, data-driven power output machine learning model development (arti?cial neural networks), weather clustering assessment (K-means clustering), post-processing output optimisation (linear regressive correction method) and the ?nal performance accuracy evaluation. The results showed that the application of linear regression coe?cients to the forecasted outputs of the developed day-ahead photovoltaic power production neural network improved the performance accuracy by further correcting solar irradiance forecasting biases. The resulting optimised model provided a mean absolute percentage error of 4.7% when applied to historical system datasets. Finally, the model was validated both, at a hot as well as a cold semi-arid climatic location, and the obtained results demonstrated close agreement by yielding forecasting accuracies of mean absolute percentage error of 4.7% and 6.3%, respectively. The validation analysis provides evidence that the proposed model exhibits high performance in both forecasting accuracy and stability.
关键词： Performance,Forecasting,Machine learning,Photovoltaic,Arti?cial neural networks,Clustering
更新于2025-09-23 15:21:01
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Photovoltaic parameters and stability study of HTM-free mixed-cation perovskite solar cells by incorporating additives to absorbing layers
摘要： In this study, quick route-coating is practiced to substitute methyl ammonium (MA) cation with formamidinium (FA) at different ratios. Through optimizing the MA:FA ratio, a maximum power conversion efficiency (PCE) of 8.31% is achieved for holes transporting material-free MA0.8FA0.2PbI3 mixed PSCs with the JSC of 19.02 mA/cm2, VOC of 0.859 V and FF of 50.88%. Then, to improve the performance, stability and carrier transport dynamic, various additives (PVA, PVP, PEG and EC) are incorporated into the perovskite layer. The treatment of perovskites with additives has proved to cause significant changes in the surface roughness, charge accumulation, charge transport, charge transport resistance, photovoltaic performance and cell stability. PCE of the PSCs mixed with PVA, PVP, EC and PEG optimally reaches 12.76%, 11.28%, 10.38% and 8.92%, respectively. Among the additives, EC and PVP provide better stability owing to the excellent interaction between the functional group of the additives and the perovskite. Surface modification and charge transport also occur better with those two additives.
关键词： Charge transport,Perovskite solar cells,Stability,Additives,Photovoltaic performance
更新于2025-09-23 15:21:01