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This study interprets the effect of using sand or gravel as energy storage unit in solar chimney power plants. The effect of using low-cost materials is evaluated. Based on the Manzanares pilot plant, a 3D CFD model is created. Geometric parameters are kept constant in simulations performed with ANSYS FLUENT engineering commercial software. By simultaneously solving DO (discrete ordinates) solar ray tracing algorithm and RNG k-ε turbulence model, the outputs of the system are examined at 290 and 300 K temperatures. The temperature distribution and power outputs of the use of sand and gravel as soil material at different temperatures and solar radiation are compared. It is understood that the use of both materials does not significantly affect the performance of the system and can be used economically instead of each other. It is seen that the system will give a power output of approximately 41.636 kW with both storage materials at a radiation intensity of 800 W/m2 and an ambient temperature of 300 K. It is seen that the ambient temperature affects the temperature increase in the system, and the temperature increase is higher at 290 K. [ABSTRACT FROM AUTHOR]

Merrigan, JJ, Stone, JD, Wagle, JP, Hornsby, WG, Ramadan, J, Joseph, M, and Hagen, JA. Using random forest regression to determine influential force-time metrics for countermovement jump height: a technical report. J Strength Cond Res 36(1): 277–283, 2022—The purpose of this study was to indicate the most influential force-time metrics on countermovement jump (CMJ) height using multiple statistical procedures. Eighty-two National Collegiate Athletic Association Division I American football players performed 2 maximal-effort, no arm-swing, CMJs on force plates. The average absolute and relative (i.e., power/body mass) metrics were included as predictor variables, whereas jump height was the dependent variable within regression models (p < 0.05). Best subsets regression (8 metrics, R 2 = 0.95) included less metrics compared with stepwise regression (18 metrics, R 2 = 0.96), while explaining similar overall variance in jump height (p = 0.083). Random forest regression (RFR) models included 8 metrics, explained ∼93% of jump height variance, and were not significantly different than best subsets regression models (p > 0.05). Players achieved higher CMJs by attaining a deeper, faster, and more forceful countermovement with lower eccentric-to-concentric force ratios. An additional RFR was conducted on metrics scaled to body mass and revealed relative mean and peak concentric power to be the most influential. For exploratory purposes, additional RFR were run for each positional group and suggested that the most influential variables may differ across positions. Thus, developing power output capabilities and providing coaching to improve technique during the countermovement may maximize jump height capabilities. Scientists and practitioners may use best subsets or RFR analyses to help identify which force-time metrics are of interest to reduce the selectable number of multicollinear force-time metrics to monitor. These results may inform their training programs to maximize individual performance capabilities. [ABSTRACT FROM AUTHOR]

In the present study, wind tunnel experiments were performed to investigate the power and thrust characteristics of a wind turbine model subjected to a variety of surge and sway motions. The turbine model was mounted on a translational stage to simulate the surge and sway motions at prescribed amplitudes and frequencies. The power output and rotor thrust were measured in each sets of the motion frequencies and amplitudes, respectively; and the measurements were also performed in a base-fixed turbine for comparison. Results show that the surge and sway motions with various amplitudes and frequencies all have slight impact on the mean power output and mean rotor thrust of a wind turbine. However, the rotor thrust fluctuations of the surging turbine, not only appeared significantly higher than those of the swaying turbine and base-fixed turbine at the same sets of amplitudes and frequencies, but also increased with the surge frequency and surge amplitude. Moreover, for both the surging and swaying turbine, the rotor thrust fluctuated with the same period as the surge and sway motions, respectively; and the power spectral density of the rotor thrust both exhibited a peak at the motion frequency and its odd multiple frequencies. • Turbine power and thrust characteristics under surge and sway motions were studied. • Motions had slight effect on mean turbine power and thrust in various conditions. • Thrust fluctuations of surging turbine were higher than swaying and fixed turbine. • Surging turbine thrust fluctuations increased with surge frequency and amplitude. • The PSD of thrust for surging and swaying turbine peaked at motion frequency. [ABSTRACT FROM AUTHOR]

In this narrative review the potential and importance of handcycling are evaluated. Four conceptual models form the framework for this review; (1) the International Classification of Functioning, Disability and Health; (2) the Stress-Strain-Capacity model; (3) the Human-Activity-Assistive Technology model; and (4) the power balance model for cyclic exercise. Based on international handcycle experience in (scientific) research and practice, evidence-based benefits of handcycling and optimization of handcycle settings are presented and discussed for rehabilitation, daily life and recreational sports. As the load can be distributed over the full 360° cycle in handcycling, peak stresses in the shoulder joint and upper body muscles reduce. Moreover, by handcycling regularly, the physical capacity can be improved. The potential of handcycling as an exercise mode for a healthy lifestyle should be recognized and advocated much more widely in rehabilitation and adapted sports practice. The interface between handcycle and its user should be optimized by choosing a suitable person-specific handcycle, but mainly by optimizing the handcycle dimensions to one's needs and desires. These dimensions can influence efficient handcycle use and potentially improve both endurance and speed of handcycling. To optimize performance in rehabilitation, daily life and recreational sports, continued and more systematic research is required. Handcycling allows users to travel farther distances at higher speeds and to train outdoors. It should be recognized as an alternative exercise modality for daily outdoor use, also already in early rehabilitation, while it contributes to a healthy lifestyle. To individualize handcycle performance, the user-handcycle (assistive device) interface as well as the vehicle mechanics should be optimized to minimize external power and reduce friction, so that the upper body capacity can be efficiently used. To optimize handcycling individual performance, both the physiological and biomechanical aspects of handcycling should be considered when monitoring or testing handcycle exercise. [ABSTRACT FROM AUTHOR]

With the daily rise in environmental issues due to the use of conventional fuels, researchers are motivated to use renewable energy sources. One of such waste heat and low-temperature differential driven energy sources is the Stirling engine. The performance of the Stirling engine can be improved by finding out the optimum operating and geometrical parameters with suitable working gas and thermal model. Based on this motivation, the current work focuses on the multiobjective optimization of the Stirling engine using the finite speed thermodynamic model and methane gas as the working fluid. Considering output power and pressure drop as two objective functions, the system is optimized using 11 geometrical and thermal design parameters. The optimization results are obtained in the form of the Pareto frontier. A sensitivity assessment is carried out to observe the decision variables, which are having a more sensitive effect on the optimization objectives. Optimization results reveal that 99.83% change in power output and 78% change in total pressure drop can take place in the two-dimensional optimization space. The optimal solution closest to the ideal solution has output power and pressure drop values as 12.31 kW and 22.76 kPa, respectively. [ABSTRACT FROM AUTHOR]

Solar chimney power plants (SCPPs) are very attractive solar energy systems with low maintenance costs and zero CO2 emissions. After its first application, the Manzanares facility, numerous studies were conducted related to the impact of geometric and climatic parameters on the system. In this study, the impact of chimney diameter change on the system, which has not been adequately examined in literature, has been investigated in detail. In the 3D CFD model created with ANSYS commercial software, simulations have been conducted by using the solar ray tracing algorithm and DO (discrete ordinates) model along with RNG k-e turbulence model. By referencing the Manzanares facility for the other geometric parameters, system behaviour has been assessed by changing the chimney diameter between 4.865-64.866 m. The impact of the change in tower diameter on the pressure and velocity distribution in the system has been analysed first in comparison with the reference situation. In addition, the influence of diameter change on the power output, mass flow rate, efficiency of the system and the average pressure difference at the turbine position has been evaluated. It has been concluded that the chimney diameter value that gives maximum performance for the Manzanares pilot plant is 24.325 m. When the chimney diameter has been configured as 24.325 m, it has been seen that the power output will improve by 85.9% compared to the reference situation and will be 101 kW. Similarly, the efficiency rises by 94% in comparison with the reference case, and becomes 0.194%. [ABSTRACT FROM AUTHOR]

The study aimed to investigate the relationship between laboratory-assessed variables and crosscountry marathon mountain biking (XCM-MTB) performance to suggest a more practical approach to monitor performance during the competitive phase. Nine elite athletes performed a battery of tests during the competitive phase of the season, one week before the race. Correlations between the physiological and neuromuscular laboratory-assessed variables and mean race completion time were verified and a multiple regression model was calculated. Cycling economy (r=0.86), power output at the first (POVT1; r=-0.73) and second ventilatory threshold (POVT2; r=-0.94), VO2peak (r=-0.71), peak power output (r=-0.91); peak power (r=-0.80), and mean power (r=-0.85) were very strongly related to race performance. TMG-derivate factors as rectus femoris (r=-0.61) and biceps femoris (r=-0.59) contraction velocity, 30-cm drop jump performance (r=-0.59), mean propulsive power in jump squat at 40% (JS40%; r=-0.65) and 60% (JS60%; r=-0.62) of athlete's body weight and lower limbs maximal isometric voluntary strength (r=-0.59) were strongly related to race completion time. In an isolated way, the POVT2 explained 87% of race performance. Although both physiological and neuromuscular variables are related to XCM performance, the POVT2 seems to be the main variable during the competitive phase and an easy-to-apply approach should be used to monitor athletes' performance. [ABSTRACT FROM AUTHOR]

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The emerging demand for bioinspired soft robotics requires novel soft actuators whose performance exceeds conventional rigid ones. Dielectric elastomer actuators (DEAs) are a promising soft actuation technology with large actuation strain and fast response. Cone DEAs are one of the most widely adopted DEA configurations for their compact structure and large force/stroke output with several configuration variations developed in recent years. By driving at a resonant frequency, the cone DEAs show a significant amplification in their power outputs, which demonstrates their suitability for highly dynamic robotic applications. However, it is still unclear how the payload conditions could affect the power outputs of cone DEAs and no work has compared the output performance of different variations of cone configurations. In this article, by considering conical configuration DEAs with generalized dissipative payloads, we conduct an extensive study on the effects of payload conditions on the power outputs of the cone DEA family. Additionally, we benchmark the performance of different cone DEA configurations and illustrate the fundamental principles behind these output patterns. The findings reported in this article establish guidelines for designing high-performance cone DEA actuators. [ABSTRACT FROM AUTHOR]

By using finite time thermodynamics, a modified endoreversible simple closed Brayton cycle with one isothermal heating process and variable isothermal pressure drop ratio is established in this paper. The cycle is composed of a compressor, a regular combustion chamber, a converging combustion chamber, a turbine and a precooler. Three variable temperature heat reservoirs are considered. The dimensionless power density is selected as the optimization objective, and the effects of inlet temperature ratios of combustion chambers on the optimal performances are studied. The results show that adding a convergent combustion chamber to the cycle can increase the dimensionless power density by 18.57%. There exit the optimal heat conductance distributions among three heat exchangers and the optimal pressure ratio leading to maximum dimensionless power density. The Pareto front based on dimensionless power output, thermal efficiency and dimensionless power density is further obtained by applying NSGA-II algorithm, and three decision methods are employed to choose the appropriate schemes from Pareto front. The different optimization schemes gained in this paper can satisfy different design demands for practical Brayton cycle power plants.

Abstract Background Handrim wheelchair propulsion is often assessed in the laboratory on treadmills (TM) or ergometers (WE), under the assumption that they relate to regular overground (OG) propulsion. However, little is known about the agreement of data obtained from TM, WE, and OG propulsion under standardized conditions. The current study aimed to standardize velocity and power output among these three modalities to consequently compare obtained physiological and biomechanical outcome parameters. Methods Seventeen able-bodied participants performed two submaximal practice sessions before taking part in a measurement session consisting of 3 × 4 min of submaximal wheelchair propulsion in each of the different modalities. Power output and speed for TM and WE propulsion were matched with OG propulsion, making them (mechanically) as equal as possible. Physiological data and propulsion kinetics were recorded with a spirometer and a 3D measurement wheel, respectively. Results Agreement among conditions was moderate to good for most outcome variables. However, heart rate was significantly higher in OG propulsion than in the TM condition. Push time and contact angle were smaller and fraction of effective force was higher on the WE when compared to OG/TM propulsion. Participants used a larger cycle time and more negative work per cycle in the OG condition. A continuous analysis using statistical parametric mapping showed a lower torque profile in the start of the push phase for TM propulsion versus OG/WE propulsion. Total force was higher during the start of the push phase for the OG conditions when compared to TM/WE propulsion. Conclusions Physiological and biomechanical outcomes in general are similar, but possible differences between modalities exist, even after controlling for power output using conventional techniques. Further efforts towards increasing the ecological validity of lab-based equipment is advised and the possible impact of these differences -if at all- in (clinical) practice should be evaluated.

The aims of this study were to compare the outcomes and provide reference data for a set of barbell mechanical parameters collected via a linear velocity transducer in 126 male sprinters (n = 62), rugby players (n = 32), and soccer players (n = 32). Bar-velocity, bar-force, and bar-power outputs were assessed in the jump-squat exercise with jump-squat height determined from bar-peak velocity. The test started at a load of 40% of the athletes’ body mass (BM), and a load of 10% of BM was gradually added until a clear decrement in the bar power was observed. Comparisons of bar variables among the three sports were performed using a one-way analysis of variance. Relative measures of bar velocity, force, and power, and jump-squat height were significantly higher in sprinters than in rugby (difference ranging between 5 and 35%) and soccer (difference ranging between 5 and 60%) players across all loads (40–110% of BM). Rugby players exhibited higher absolute bar-power (mean difference = 22%) and bar-force (mean difference = 16%) values than soccer players, but these differences no longer existed when the data were adjusted for BM (mean difference = 2.5%). Sprinters optimized their bar-power production at significantly greater relative loads (%BM) than rugby (mean difference = 22%) and soccer players (mean difference = 25%); nonetheless, all groups generated their maximum bar-power outputs at similar bar velocities. For the first time, we provided reference values for the jump-squat exercise for three different bar-velocity measures (i.e., mean, mean propulsive, and peak velocity) for sprinters, rugby players, and soccer players, over a wide range of relative loads. Practitioners can use these reference values to monitor their athletes and compare them with top-level sprinters and team-sport players.

Bu çalışmada toplayıcı eğiminin sisteme etkisi Manzanares prototipi esas alınarak geliştirilen 3 boyutlu CFD modeli ile analiz edilmektedir. Nümerik modelde güneş yükü için DO (discrete ordinates) ışınım modeli ve sistem içerisindeki hava hareketi için RNG k-ε türbülans modeli birleştirilerek uygulanmaktadır. 1000 W/m2 güneş ışınımında sistemdeki maksimum hız 14.3 m/s olarak bulunurken bu değer deneysel veri olan 15 m/s ile uyum içerisindedir. Manzanares prototipinde toplayıcı giriş yüksekliği 1.85 m olarak verilmektedir. Bu çalışma kapsamında toplayıcı giriş yüksekliği sabit tutularak, toplayıcı çıkış yüksekliği sırası ile 2.91, 3.97, 5.04, 6.12 ve 7.17 m olarak tasarlanmakta ve bu sayede toplayıcı eğiminin 0.5, 1, 1.5, 2 ve 2.5° olduğu durumlarda sistemin performansındaki değişim değerlendirilmektedir. Elde edilen sonuçlar toplayıcı eğimindeki artışın sistemdeki hava hareketinin kütlesel debisini arttırdığını ve bu artışın sistemin güç çıkışını iyileştirdiğini göstermektedir. Referans durumu temsil eden eğimsiz toplayıcı için toplayıcı verimi %38.7 iken toplayıcı eğimi 1° olduğunda verimin %41.5’e iyileştiği gözlenmektedir. Sistemin çıkış gücü referans durumda 54.5 kW iken toplayıcı eğimi 2.5° olduğunda 57.1 kW olarak belirlenmektedir.

The engineering structures consist of machine foundations, pavement, subgrade, bridge abutment, railway track, retaining wall, and contact geo-material. These structures are subjected to ambient mechanical vibration due to dynamic loads. The mechanical vibration of the structures can be utilized for power generation using the electromechanical conversion characteristics of the piezoelectric material. This paper captures recent advances in modelling PEH (piezoelectric energy harvester) and numerical techniques for power generation from structures. The electromechanical coupling of the structures with PEH is the key factor for the voltage and power output. The coupling techniques of structures and energy harvesters are significantly affected by the variables, namely fundamental frequency, the contact pressure of loading, the geometry of the structure, moving load frequency, placement of harvester, and dynamic response of the contact material. The mode of operation of PEH (31 vs. 33 modes) significantly influences the dynamic input and power output from the structure-power generation system. The present study demonstrates the potential of power generation from mechanical vibration of geo-structures has been classified as low, moderate, and high power output. It recommends the coupling parameters for the structural design to improve the efficacy of power generation from the ambient vibration of geo-structures.

ABSTRACT The aim was to verify the reliability and sensitivity of countermovement jump (CMJ) derived variables in detecting small, moderate and large changes and whether the capacity of CMJ-derived variables in detecting fatigue is dependent of the volume of the fatiguing exercise. Seventeen physically active men performed two fatigue protocols, on separate weeks, composed by continuous vertical jumps: short protocol (7 x 10 jumps) and long protocol (14 x 10 jumps). Jump height (JH), power output (PO), impulse (IMP) and vertical stiffness (KVERT) were measured during CMJ prior to and immediately after the fatigue protocols. Intraclass coefficient correlation, typical error, smallest worthwhile change and magnitude-based inference were analyzed. PO and JH presented excellent reliability and good sensitivity to detect small and medium changes, respectively. Negative effects of fatigue could be detected most likely by PO, regardless of fatiguing exercise volume. JH and IMP seem to be affected only after long protocol and KVERT only after short protocol. In conclusion, PO (peak and mean) is the better marker in CMJ with excellent reliability and sensibility, which allows detect even the small effects and differentiate the fatigue levels.

IntroductionThe Concept 2 (C2) rowing ergometer is used worldwide for home-based training, official competitions, and performance assessment in sports and science. Previous studies reported a disparate underestimation of mechanical power output positively related to an unclearly defined stroke variability. The aim of this study was to quantify the accuracy of the C2 while controlling for the potentially influencing variables of the rowing stroke by using a test rig for air-braked rowing ergometers and thus excluding biological variability.MethodsA unique motorized test rig for rowing ergometers was employed. Accuracy was assessed as the difference in mechanical power output between C2 and a reference system during steady (i.e., minimal variations of stroke power within a series of 50 spacemark, no -strokes) and unsteady simulated rowing (i.e., persistent variations during measurement series) while manipulating the stroke variables shape, force, or rate.ResultsDuring steady simulated rowing, differences between C2 and the reference system ranged 2.9–4.3%. Differences were not significantly affected by stroke shapes (P = 0.153), but by stroke rates ranging 22–28 min−1 (P < 0.001). During unsteady simulated rowing with alterations of stroke force and rate, mean differences of 2.5–3.9% were similar as during steady simulated rowing, but the random error increased up to 18-fold. C2 underestimated mechanical power output of the first five strokes by 10–70%. Their exclusion reduced mean differences to 0.2–1.9%.ConclusionDue to the enormous underestimation of the start strokes, the nominal accuracy of the C2 depends on the total number of strokes considered. It ranges 0.2–1.9%, once the flywheel has been sufficiently accelerated. Inaccuracy increases with uneven rowing, but the stroke shape has a marginal impact. Hence, rowers should row as even as possible and prefer higher stroke rates to optimize C2 readings. We recommend external reference systems for scientific and high-performance assessments, especially for short tests designs where the start strokes will have a major impact.

Inorganic ternary type materials are induced compound is worked as fundamental applications in transformation of the solar light energy into electrical energy. Copper zinc selenide thin films have been synthesized by chemical bath deposition method on to stainless steel plate. The configuration of fabricated cell is p-Cu0.5Zn0.5Se| NaOH(1M) + S(1M) + Na2S(1M) |C(graphite). The Photovoltaic cell characterization of the films is carried out by studying current–voltage characteristics in dark, capacitance–voltage in dark, barrier height measurements, power output, photoresponse and spectral response. The study shows that Cu0.5Zn0.5Se thin films are p-type conductivity. The junction ideality factor was found to be 2.93. The flat band potential was found to be -0.708V. The barrier height value was found to be 0.186 eV. The study of power output characteristic shows open circuit voltage, short circuit current, fill factor and efficiency were found to be 150 mV, 21 μA, 42.13%, and 0.63%, respectively. Photoresponse shows lighted ideality factor is 2.89. Spectral response shows the maximum current observed at 580 nm.

While poly(vinylidene fluoride-trifluoroethylene) (P(VDF-TrFE)) film is an excellent piezoelectric material for mechanical energy harvesting, the piezoelectric output varies considerably with the spin coating conditions. Herein, we reported a systematic evaluation of the structural, electrical, mechanical, and microstructural properties of spin-coated P(VDF-TrFE) films obtained at various distances from the center, as well as under different rotational speeds. With increasing distance, the remnant polarization, dielectric constant, and crystallinity of the films increased, which resulted in enhanced piezoelectric power at the largest distance. With increasing rotational speed, the remnant polarization, dielectric constant, and crystallinity of the films initially increased and then decreased, while the Young’s modulus continuously increased. This resulted in an enhanced piezoelectric power at a given rotational speed. The piezoelectric power is proportional to the remnant polarization and inversely proportional to the Young’s modulus. The highest (2.1 mW) and lowest (0.5 mW) instantaneous powers were obtained at the largest (1.09 μC/cm2·GPa−1) and smallest (0.60 μC/cm2·GPa−1) value of remnant polarization over Young’s modulus, respectively. We explain these behaviors in terms of the centrifugal force-induced shear stress and grain alignment, as well as the thickness-dependent β-phase crystallization and confinement. This work implies that the spin coating conditions of distance and rotational speed should be optimized for the enhanced power output of spin-coated P(VDF-TrFE)-based piezoelectric nanogenerators.

CO2 lasers have been generally used in oral soft-tissue surgery. Although an increase in power enhances the depth of ablation, the specific correlation between units of power and ablative depth has not been stated. This study aimed to explore ablative depth and width affected by a power unit of 10,600-nm CO2 laser continuous wave at 3 to 10 W in tissue blocks of the swine tongue. The 112 samples were randomly allocated into eight groups according to the power settings. The depth and width of the incision were measured by using the ImageJ program. The 3 W group showed the minimal depth of ablation [0.527 mm (0.474 and 0.817)] and width of ablation [0.147 mm (0.110 to 0.184)]. The maximal depth [3.750 mm (3.362 and 4.118)] and width [0.700 mm (0.541 to 0.860)] were in the 9 W group. The correlation between the ablative depth and power unit was 0.81 (p < 0.001). Based on the regression equation (p < 0.001), the ablative depth (mm) = (the power unit of laser in W × 0.491) − 0.731. In conclusion, the ablative depth of the CO2 laser on soft tissue was strongly correlated to power units enabling the prediction equation.

We report the magnificent thermoelectric properties of the n-type Ag 2 Se film printed onto a flexible polyimide (PI) substrate. The orthorhombic β-Ag 2 Se phase of the processed Ag 2 Se film is confirmed from the X-ray diffractogram. Remarkably, the resulting Ag 2 Se/PI film exhibits outstanding thermoelectric properties, boasting maximum power factors of 1.4 and 2.1 mW/mK 2 at 300 and 405 K, respectively. Furthermore, the flexibility of the Ag 2 Se/PI film remains intact even after undergoing 1500 bending cycles with no degradation observed in its thermoelectric performance. To demonstrate the practical application of our findings, a flexible thermoelectric prototype is constructed using the fabricated Ag 2 Se/PI films, which can harvest an impressive output voltage of 52 mV across a temperature difference of 53 K. Additionally, the prototype generates a maximum power output of 7.2 μW with a 40 K temperature difference and can produce 13 mV output voltage when subjected to around a 10 K temperature gradient when the cold side temperature is maintained at 308 K. Moreover, leveraging body heat with just a 1 K temperature variance between the body and the surrounding environment, the prototype could yield an impressive voltage output of 1.6 mV, marking the highest reported voltage output from human body heat to date. Our study not only introduces a cost-effective method for producing high-performance flexible thermoelectric films but also highlights their potential applications in wearable and implantable electronics.

Several studies have shown that actuation concepts such as Serial elastic actuator (SEA) can reduce peak power and energy consumption in ankle prostheses. Proper selection and design of the actuation concepts is important to unlock the power source potential. In this work, the optimization design, mechanical design, control scheme, and bench experiments of a new powered ankle–foot prosthesis is proposed. The actuation concept of this prosthesis is parallel elastic actuator (PEA) composed of electro-hydrostatic actuator (EHA) as the power kernel and a unidirectional parallel spring as the auxiliary energy storage element. After the appropriate motor and transmission ratio was selected, a dynamic model of the PEA prosthesis was built to obtain the appropriate spring parameters driven by biological data. The design of the hydraulic and mechanical system and the controller were provided for the implementation of the designed system. Bench experiments were performed to verify the performance. The results showed that the designed prosthesis meets the biomechanical dynamics requirements. This result emphasizes the feasibility of the EHA as a power source and actuator and provides new ideas for the design of ankle–foot prostheses.

More insight into in-field mechanical power in cyclical sports is useful for coaches, sport scientists, and athletes for various reasons. To estimate in-field mechanical power, the use of wearable sensors can be a convenient solution. However, as many model options and approaches for mechanical power estimation using wearable sensors exist, and the optimal combination differs between sports and depends on the intended aim, determining the best setup for a given sport can be challenging. This review aims to provide an overview and discussion of the present methods to estimate in-field mechanical power in different cyclical sports. Overall, in-field mechanical power estimation can be complex, such that methods are often simplified to improve feasibility. For example, for some sports, power meters exist that use the main propulsive force for mechanical power estimation. Another non-invasive method usable for in-field mechanical power estimation is the use of inertial measurement units (IMUs). These wearable sensors can either be used as stand-alone approach or in combination with force sensors. However, every method has consequences for interpretation of power values. Based on the findings of this review, recommendations for mechanical power measurement and interpretation in kayaking, rowing, wheelchair propulsion, speed skating, and cross-country skiing are done.

Purpose: To examine pacing strategies of ultracyclists competing in the Race Across AMerica (RAAM), the world's longest ultracycling race, covering ~4860 km from the West to the East coast of America. Methods: Age, cycling speed at and across time stations, race distance, relative difference in altitude between time stations, wind velocity, wind gradient, and temperature at each time station were recorded for women and men competing from 2010 to 2014. Changes in cycling speed and power output of elite and age-group finishers were analyzed using mixed-effects regression analyses. Results: Cycling speed decreased across time stations for women and men where men were faster than women. Power output decreased across time stations in women and men and was lower for women for all finishers, the annual 3 fastest, and age group 60-69 y but not for age groups 18-49 and 50-59 y. The change in temperature and altitude had an influence on cycling speed and power output in all finishers, the annual top 3, nonfinishers, and in all different age groups for both women and men but in the age group 50-59 y altitude had no influence on cycling speed. Conclusions: Positive pacing (ie, decrease in speed throughout the race) seemed to be the adequate strategy in the RAAM. The top 3 finishers started faster and had a higher power output at the start than less successful competitors, achieved the highest peak cycling speeds and power output, and maintained peak cycling speed and power output longer before slowing down. [ABSTRACT FROM AUTHOR]

The oral presence of carbohydrate (CHO) and caffeine (CAF) may independently enhance exercise performance, but their influence on performance during prolonged exercise is less known. Aim: To determine the independent and combined effects of CHO and CAF administered in chewing gum during a cycling time trial (TT) after prolonged exercise. Method: Eleven male cyclists (32.2 ± 7.5 y, 74.3 ± 6.8 kg, 60.2 ± 4.0 mL • kg-1 • min-1 V02peak) performed 4 experimental trials consisting of 90-min constant-load cycling at 80% of their second ventilatory threshold (207 ± 30 W), followed immediately by a 20-km TT. Under double-blinded conditions, cyclists received placebo (PLA), CHO, CAF, or a combined CHO+CAF chewing gum at 0-, 5-, 10-, and 15-km points of the TT. Results: Overall TT performance was similar across experimental and PLA trials (%mean difference ± 90%CL 0.2% ± 2.0%, 0.4% ± 2.2%, 0.1 % ± 1.8% for CHO, CAF, and CHO+CAF). Compared with PLA, mean power output tended to be higher in the first 2 quarters of the TT with CHO (1.6% ± 3.1% and 0.8% ± 2.0%) and was substantially improved in the last 2 quarters during CAF and CHO+CAF trials (4.2% ± 3.0% and 2.0% ± 1.8%). There were no differences in average heart rate (ES <0.2) and only small changes in blood glucose (ES 0.2), which were unrelated to performance. Blood lactate was substantially higher post-TT for CAF and CHO+CAF (ES >0.6). Conclusion: After prolonged constant-load cycling, the oral presence of CHO and CAF in chewing gum, independently or in combination, did not improve overall performance but did influence pacing. [ABSTRACT FROM AUTHOR]

Purpose: To verify the hypothesis that the peak power (PP) of a Wingate test (WT) is an underestimation of maximal power (Pmax) computed from the force-velocity test (FVT), to examine possible fatigue effect on Pmax. and to investigate the effect of load on mean power (MP) and fatigue index (FI) during a WT in trained and recreational men. Methods: Ten recreational (22.9 ± 1.7 y, 1.81 ± 0.06 m, 73.3 ± 10.4 kg) and 10 highly trained subjects (22.7 ± 1.4 y, 1.85 ± 0.05 m, 78.9 ± 6.6 kg) performed 2 WTs with 2 loads (8.7% and 11% of body mass [BM]) and an FVT on the same cycle ergometer, in randomized order. Results: Optimal load was equal to 10% BM in recreational participants. Given the quadratic relationship between load and power, the underestimation of Pmax was lower than 10% for the average values of trained and recreational participants with both loads. However, PP with a load equal to 8.7% BM was a large underestimation (-30%) of Pmax in the most powerful individuals. In addition, PP was not greater than Pmax of FVT for the same load. FI was independent of the load only if it was expressed relative to PP. The optimal load for MP during WT was close to the optimal load for PP. Conclusions: The optimal load for WT performance should be approximately equal to 10% BM in recreational subjects. In powerful subjects, the FVT appears to be more appropriate in assessing maximal power, and loads higher than 11% BM should be verified for the WT. [ABSTRACT FROM AUTHOR]

This study aimed to compare the kinetics between the push press (PP), push jerk (PJ), and split jerk (SJ). Sixteen resistance-trained participants (12 men and 4 women; age: 23.8 ± 4.4 years; height: 1.7 ± 0.1 m; body mass: 75.7 ± 13.0 kg; weightlifting experience: 2.2 ± 1.3 years; one repetition maximum [1RM] PP: 76.5 ± 19.5 kg) performed 3 repetitions each of the PP, PJ, and SJ at a relative load of 80% 1RM PP on a force platform. The kinetics (peak and mean force, peak and mean power, and impulse) of the PP, PJ, and SJ were determined during the dip and thrust phases. Dip and thrust displacement and duration were also calculated for the three lifts. In addition, the inter-repetition reliability of each variable across the three exercises was analysed. Moderate to excellent reliability was evident for the PP (Intraclass correlation coefficient [ICC] = 0.91–1.00), PJ (ICC = 0.86–1.00), and SJ (ICC = 0.55–0.99) kinetics. A one-way analysis of variance revealed no significant or meaningful differences (p > 0.05, η2  ≤ 0.010) for any kinetic measure between the PP, PJ, and SJ. In conclusion, there were no differences in kinetics between the PP, PJ, and SJ when performed at the same standardised load of 80% 1RM PP. [ABSTRACT FROM AUTHOR]

Background: The Wingate test is usually conducted using resistance loads of 7.5, 8.5 or 8.7 g.kg−1 of body mass. However, these cycle ergometer resistance loads may be insufficient to enable maximal power values. As such, the use of individual optimal load selection (OPT) can positively influence other Wingate test parameters. Moreover, anthropometric parameters, e.g. body mass index, may also affect the OPT, but have not been well investigated. Aim: To investigate (i) individual OPT on the Wingate Test for peak power (PP), mean power outputs (MP), and the fatigue index (FI) and (ii) the association between OPT and anthropometric parameters. Methods: Fifteen physically active men (age = 26.4 ± 4.1 yr) performed six 30-s Wingate tests, with loads corresponding to 6.5%, 8.5%, 10.5% 11.5% 12.5%, and 13.5% of body mass to determine OPT (the load corresponding with the highest peak power), and also PP, MP, and FI. Results: Peak Power was 15% higher (p<0.001) and FI was 21% higher (p=0.03) for the OPT method, whereas Mean Power values were similar between OPT and the 8.5% of body mass load. The 8.5% of body mass resistance load underestimates power outputs and is directly related to individual Peak Power (r=0.58, p=0.02). Furthermore, the load corresponding to OPT was inversely correlated to body mass index (r=−0.81, p<0.001) and percent body fat (r=−0.51, p=0.04). Conclusion: Optimal load selection is more appropriate than the use of 8.5% of body mass load to enable higher Peak power in the 30-s Wingate test in a physically active male population. [ABSTRACT FROM AUTHOR]

Karachi, Pakistan has great solar energy potential. Solar energy can be converted to electricity using photovoltaic (PV) technology. Dust accumulation can significantly suppress the performance of the PV modules. This research work is the first experimental study to examine the effect of dust deposition on the surface of PV modules in Karachi, Pakistan. An experimental setup of polycrystalline modules has been created by connecting three panels in a parallel arrangement. These panels were placed in an outdoor environment for one year to determine output power, efficiency and performance ratio. The results of this study indicated that the dust deposition on PV modules can cause an average reduction of 14.6 W/month in power, 0.3%/month in efficiency and 1.84% in performance ratio in the environment of Karachi. For PV modules of 780 W, the performance of PV modules is reduced by 2.21% due to dust deposition. [ABSTRACT FROM AUTHOR]

Purpose. Resistance exercise (rE) with variable resistance (Vr) may be an interesting strategy to increase strength and power in several sports activities. The present study aimed to compare the effect of rE vs. Vr exercise in the back squat on subsequent jump performance at different time points. Methods. Nine male elite handball athletes (age: 21.4 ± 2.1 years; body fat percentage: 10.5 ± 4.2%) undergoing in-season training participated in the study. they randomly completed 3 sets of 5 back squat repetitions at 85% of predicted one-repetition maximum (1rM) with 3-minute rests between sets. they performed rE back squat alone or Vr back squat by combining 55% of 1rM using standard weight plates and 29.7 ± 2.0% of the athlete's 1rM in fully erect position (starting position) with elastic band resistance. Countermovement jump (CMJ) test was applied at baseline, immediately after the conditioning activity (within 15 seconds), and every 2 minutes after the protocols (2, 4, 6, and 8 minutes). Results. there was a very large (5.8%, p = 0.02, ES = 1.53) increase in CMJ performance 2 minutes after Vr back squat, while no significant changes were observed after the completion of rE back squat. Moreover, there was a large (p = 0.04, ES = 1.27) increase in peak power after Vr exercise. Conclusions. CMJ performance and peak power output can be potentiated after 2 minutes of recovery following the completion of back squat exercise combining rE plus elastic bands, reinforcing the practical applicability of Vr exercise. [ABSTRACT FROM AUTHOR]

Understanding the effect of thermal stratification on wind turbine wakes in complex terrain is essential to optimize wind farm design. The effect of a three-dimensional hill on the performance of a downwind turbine is studied by performing large eddy simulations for different atmospheric conditions. The distance between the hill and the turbine is six times the turbine diameter, and the hill height is equal to the hub height. It is shown that the hill wake reduces the power production of the downstream turbine by 35 % for the convective boundary layer case under consideration. However, surprisingly, the wind turbine power production is increased by about 24 % for the stable boundary layer case considered here. This phenomenon results from the entrainment of kinetic energy from the low-level jet due to the increased mixing induced by the hill wake. This effect strongly depends on the Coriolis force-induced wind veer. The increased turbulence intensity by the hill results in a strong increase in the forces experienced by the blades, which suggest the turbine is experiencing much higher unsteady turbulence loading. It is shown that the increase in the power fluctuations may not fully reflect the increase in the force fluctuations on the blades. • Hill wake can improve the power production of the downstream turbine. • Power increase results from the Coriolis force induced wind veer and low-level jet. • The low-level jet energy is entrained due to the hill wake induced vortex shedding. • Hill wake strongly increases the power fluctuations of the downstream turbine. • Force fluctuations on blades are stronger than power fluctuations. [ABSTRACT FROM AUTHOR]

Floating tower projects in solar chimney power plant are emerging with considerable interest. However, high chimney tower might be under great pressure from wind blow. Use of flexible fabric material for the tower might reduce the constraint on the chimney and reduce the cost. The present work is devoted to the study of the solar tower inclination impact on the efficiency of the solar chimney power plant (SCPP). The considered inclination angles of the tower are 15°, 22°, and 30°. In addition, waterbed is laid down on the ground of the collector to store heat. Results showed that a tower inclination of up to 22° might improve the performance of the SCPP. The extra heat storage also made a better use of the energy. This improved the power produced from sunset to sunrise with a lower entropy generation, mainly in the configuration with a solar tower inclination between 15° and 22°. [ABSTRACT FROM AUTHOR]

The purpose of this study was to investigate the effects of listening to preferred versus non-preferred warm-up music on anaerobic sprint performance in Division I NCAA female athletes. Female collegiate athletes (n = 14) were recruited for this study. In a counterbalanced, crossover study design, participants completed two separate visits, each with a different warm-up music condition: preferred (Pref) or non-preferred (Non-pref). During each visit, participants completed a 3 min standardized cycling warm-up at 50 Watts while listening to Pref or Non-pref music. Following this, participants completed 3 - 15 s Wingate Anaerobic Tests (WAnTs) with a 2 min active recovery period in between tests. Motivation to exercise was measured immediately following the warm-up (WU), WAnT1, WAnT2, and WAnT3. The rate of perceived exertion (RPE) was also measured after each WAnT. Each visit was separated by a minimal recovery period of 48 h. Mean power, total work, RPE, and motivation were analyzed. Mean power (p = 0.044; d = 0.91) and total work (p = 0.045; d = 0.78) were significantly higher during the Pref music condition versus Non-pref. RPE remained unchanged regardless of condition (p = 0.536; d = 0.01). Motivation was significantly higher with Pref warm-up music compared to Non-pref (p < 0.001; d = 1.55). These results show that listening to Pref warm-up music has an ergogenic benefit during repeated sprints in comparison to Non-pref music and improves motivation to exercise. Listening to warm-up music prior to high-intensity repeated exercise may aid in optimizing performance and training in collegiate athletes. [ABSTRACT FROM AUTHOR]

Through the present investigation, the thermal and power output of novel-shaped solar panels are evaluated. For the cooling of the mentioned forms, forced air flow was utilized. Three novel shapes, of Pyramid, Hexagonal, and Conical which had the equal lateral surface were considered. For the simulation, an open source CFD software was utilized. The lateral surfaces were put under identical amount of heat flux. Air as the coolant fluid was injected with constant inlet temperature from the trapdoors at the bottom of different shaped structures. Three different values of heat flux and air injection rate were evaluated for each shape. The outcomes presented that the conical shaped solar panel exhibits better thermal performance than other geometries. Furthermore, conical form finds the least temperature that was about 10.5 °C less than that of the pyramid-shaped panel. Furthermore, it was revealed that the corners of pyramid and hexagonal-shaped solar panels have higher temperature. Also, it was found that the efficiency of conical shaped panel was up to 8.4% more than that of pyramid-shaped panel.

This paper presents the experimental studies of different passive cooling techniques to analyze the electrical power improvement and temperature reduction of a 50 W polycrystalline PV module. Plant cooling, greenhouse cooling, greenhouse + plant cooling, coir pith, and phase change material cooling are the various approaches are used in the analysis. The percentage of electrical power improvement and temperature of various passive cooling techniques are compared with solar modules without cooling. The maximum percentage power improvement (11.34%) was found to be in coir pith cooling with an average maximum power of 36.38 W. The maximum temperature reduction was observed to be 14 °C in case of plant cooling with a greenhouse. Considering the electrical power improvement and temperature reduction, coir cooling and plant cooling were found to be best suited for the given climatic conditions amongst all cooling techniques. The results also showed that the reduction in temperature does not always give rise to the increase in power as it was depicted in the case of greenhouse net cooling and plant cooling with greenhouse. This kind of cooling technique is best suited for agro-based countries in tropical regions.

ABSTRAK PLTS pada penelitian ini didesain dengan sistem Off-Grid dengan kapasitas 600 Wp yang terhubung dengan MPPT 50 A, DC 150V dan energi output disimpan pada baterai VRLA 100 Ah. Pemanfaatan teknologi Internet of Things dengan komunikasi data menggunakan jalur komunikasi serial dengan modul ESP 8266. Pengujian dilakukan dengan memasang PLTS dengan kemiringan 300 pada koordinat wilayah -06°33’25’’, 107°12’39’’. Analisis data dilakukan untuk membaca performa daya output dan membandingkan dengan data total photovoltaic power output (Wh) yang dirilis Global Solar Atlas. Sampel data diambil pada bulan September 2020, 06.00-18.00 WIB, yang menunjukkan bahwa rentang waktu kerja efektif PLTS adalah 07.00-08.00 WIB dengan daya output ±140 watt, dimana mendekati nilai total photovoltaic power output adalah 143 Wh. Kata kunci: PLTS, Off-Grid, Internet of Things, power output ABSTRACT This Solar Power Plant is designed with an Off-Grid system with a capacity of 600 Wp connected to MPPT 50 A, DC 150V, and the output energy stored in a VRLA 100 Ah battery. Utilization of Internet of Things technology with data communication by serial communication line using the ESP 8266 module. Testing was carried out by installing Solar Power Plants with a slope of 300 at the coordinates of the area -06 ° 33'25 '', 107 ° 12'39 ''. Data analysis was carried out to read the output power performance and compare it with the Total photovoltaic power output (Wh) data released by Global Solar Atlas. Data samples were taken in September 2020 at 06.00-18.00 WIB, which shows the effective working time gap of PLTS at 07.00-08.00 WIB with an output power of ± 140 watts is close to the total photovoltaic power output value of 143 Wh. Keywords: Solar Power Plants, Off-Grid, Internet of Things, power output

Purpose: While a number of studies have investigated gross efficiency (GE) in laboratory conditions, few studies have analyzed it in field conditions. Therefore, the aim of this study was to analyze the effect of gradient and cadence on GE in field conditions. Methods: Thirteen trained cyclists (mean ± SD age 23.3 ± 4.1 y, stature 177.0 ± 5.5 cm, body mass 69.0 ± 7.2 kg, maximal oxygen uptake [...O2max] 68.4 ± 5.1 mL ⋅ min-1 ⋅ kg-1) completed an incremental graded exercise test to determine ventilatory threshold (VT) and 4 field trials of 6 min duration at 90% of VT on flat (1.1%) and uphill terrain (5.1%) with 2 different cadences (60 and 90 rpm). VO2 was measured with a portable gas analyzer and power output was controlled with a mobile power crank that was mounted on a 26-in mountain bike. Results: GE was significantly affected by cadence (20.6% ± 1.7% vs 18.1% ± 1.3% at 60 and 90 rpm, respectively; P < .001) and terrain (20.0% ± 1.5% vs 18.7% ± 1.7% at flat and uphill cycling, respectively; P = .029). The end-exercise ...O2 was 2536 ± 352 and 2594 ± 329 mL/min for flat and uphill cycling, respectively (P = .489). There was a significant difference in end-exercise VO2 between 60 (2352 ± 193 mL/min) and 90 rpm (2778 ±431 mL/min) (P < .001). Conclusion: These findings support previous laboratory-based studies demonstrating reductions in GE with increasing cadence and gradient that might be attributed to changes in muscle-activity pattern. [ABSTRACT FROM AUTHOR]

Purpose: To determine the effect of thermal state and thermal comfort on cycling performance in the heat. Methods: Seven well-trained male triathletes completed 3 performance trials consisting of 60 min cycling at a fixed rating of perceived exertion (14) followed immediately by a 20-km time trial in hot (30°C) and humid (80% relative humidity) conditions. In a randomized order, cyclists either drank ambient-temperature (30°C) fluid ad libitum during exercise (CON), drank ice slurry (-1°C) ad libitum during exercise (ICE), or precooled with iced towels and ice slurry ingestion (15g/kg) before drinking ice slurry ad libitum during exercise (PC+ICE). Power output, rectal temperature, and ratings of thermal comfort were measured. Results: Overall mean power output was possibly higher in ICE (+1.4% ± 1.8% [90% confidence limit]; 0.4 > smallest worthwhile change [SWC]) and likely higher PC+ICE (+2.5% ± 1.9%; 1.5 > SWC) than in CON; however, no substantial differences were shown between PC+ICE and ICE (unclear). Time-trial performance was likely enhanced in ICE compared with CON (+2.4% ± 2.7%; 1.4 > SWC) and PC+ICE (+2.9% ± 3.2%; 1.9 > SWC). Differences in mean rectal temperature during exercise were unclear between trials. Ratings of thermal comfort were likely and very likely lower during exercise in ICE and PC+ICE, respectively, than in CON. Conclusions: While PC+ICE had a stronger effect on mean power output compared with CON than ICE did, the ICE strategy enhanced late-stage time-trial performance the most. Findings suggest that thermal comfort may be as important as thermal state for maximizing performance in the heat. [ABSTRACT FROM AUTHOR]

This study investigated whether combined ingestion and mouth rinsing with a carbohydrate solution could improve maximal sprint cycling performance. Twelve competitive male cyclists ingested 100 ml of one of the following solutions 20 min before exercise in a randomized double-blinded counterbalanced order (a) 10% glucose solution, (b) 0.05% aspartame solution, (c) 9.0% maltodextrin solution, or (d) water as a control. Fifteen min after ingestion, repeated mouth rinsing was carried out with 11 x 15 ml bolus doses of the same solution at 30-s intervals. Each participant then performed a 45-s maximal sprint effort on a cycle ergometer. Peak power output was significantly higher in response to the glucose trial (1188 ± 166 W) compared with the water (1036 ± 177 W), aspartame (1088 ± 128 W) and maltodextrin (1024 ± 202W) trials by 14.7 ± 10.6, 9.2 ± 4.6 and 16.0 ± 6.0% respectively (p < .05). Mean power output during the sprint was significantly higher in the glucose trial compared with maltodextrin (p < .05) and also tended to be higher than the water trial (p = .075). Glucose and maltodextrin resulted in a similar increase in blood glucose, and the responses of blood lactate and pH to sprinting did not differ significantly between treatments (p > .05). These findings suggest that combining the ingestion of glucose with glucose mouth rinsing improves maximal sprint performance. This ergogenic effect is unlikely to be related to changes in blood glucose, sweetness, or energy sensing mechanisms in the gastrointestinal tract. [ABSTRACT FROM AUTHOR]

Wind-tunnel experiments were performed to study the effect of favorable and adverse constant pressure gradients (PG) from local changes in the topography right downwind of a model wind turbine. Particle image velocimetry was used to characterize the near and intermediate wake regions. We explored five scenarios, two favorable, two adverse PG, and a case with negligible PG. Results show that the PGs induce a wake deflection and modulate the wake. They imposed a relatively small impact on the turbulence kinetic energy and kinematic shear stress but a comparatively dominant effect on the bulk flow on the flow recovery. Based on this, a simple formulation is used to describe the impact of PG on the wake. We modeled the base flow through a linearized perturbation method; the wake is obtained by solving a simplified, integrated streamwise momentum equation. This approach reasonably estimated the flow profile and PG-induced power output variations.

[Display omitted] Organic photovoltaic (OPV) cells have found their potential applications in the harvest of indoor light photons. However, the output power of such indoor devices is usually far from the demand of the internet of things. Therefore, it is essential to boost the output power of indoor organic photovoltaics to a much higher level. As wildly deployed among industrial and civil luminous environments, thermal radiation-based indoor light sources are alternative candidates to supply the essential power of the off-grid electronics with a broad consecutive emission spectrum. In this work, we evaluated the photovoltaic performance of organic solar cells under indoor incandescent and halogen illuminations. Impressively, under such thermal radiations, an improvement over 500% of the output power density can be achieved in comparison with that under light-emitting diodes and fluorescent lamps, reaching a record high value of 279.1 μW cm−2 by the PM6:Y6-based device. The remarkable power output is originated from the extra near-infrared spectrum of indoor thermal lights, which restricts the effective area under 10 cm2 in achieving 1 mW output power. This work clarifies the feasibility of collecting photons radiated from indoor thermal light sources through OPV cells, and enlightens the further applications of indoor OPV cells under multiple illumination environments. [ABSTRACT FROM AUTHOR]

Athletes may increase power output through eliciting postactivation performance enhancement (PAPE). Muscle force and power may be increased during PAPE by coupling of 2 exercises, termed a "strength-power potentiating complex" (SPPC). Implementing SPPCs in the field is complicated by the need to use rest periods of several minutes in duration, which is impractical when training large numbers of athletes simultaneously within a short time. We propose delayed performance enhancing triplexes as a solution: which involve inserting an accessory exercise in between a heavy resistance exercise and a plyometric movement, which allows for training to continue to flow without interruption. [ABSTRACT FROM AUTHOR]

Magnetorheological (MR) dampers are becoming popular smart devices with controllable higher damping properties. This paper presents an inclusive review of energy harvesting MR dampers. The classifications of energy harvesting MR dampers, operating principles, structural design, mathematical models, fluid models, experimental investigation, and applications are classified and reviewed. The regenerative MR dampers have self-power capability, and self-sensing capability to control higher performance and it is an important feature of regenerative MR dampers. The review indicates that regenerative MR dampers have enough power generation capacity to power MR dampers and higher damping performances. It has been found that a single-ended monotube regenerative MR (RMR) damper has maximum power generation capabilities than other RMR dampers. [ABSTRACT FROM AUTHOR]

• Parametric study and optimization of installation parameters for bi-facial solar PV system. • Optimization of bi-facial solar PV using response surface methodology. • New correlations for the energy yield and bifacial gain are presented. • The coefficients of determination R2 for the new developed correlations are 0.99. • The average daily bifacial gain is 35.68% at the optimum installation parameters. Sensitivity analysis of design parameters and power gain correlations of bi-facial solar PV system is presented in this paper. The main objectives are to study the effects of albedo, tilt angle and height from the ground on the performance of the system; determine the optimum operating conditions; and the development of new correlations for the annual energy yield and bifacial gain of bPV solar system. Three primarily significant installation parameters, albedo [10%, 50%, 90%], tilt angle [15°, 25°, 35°] and height [0.5 m, 1 m, 1.5 m] are investigated with PVSYST for bifacial and mono-facial PV modules. The response surface methodology (RSM) based optimization method is used to determine the optimum conditions and the interaction of these three parameters on the performance of bPV solar system. New quadratic equations or correlations are introduced to estimate the annual energy yield and bifacial gain of bPV. The results show that the albedo is the most significant parameter between tilt angle and height. The increase in albedo factor and height of bPV modules from ground increase the energy yield. In this study, the optimum tilt angle of bPV is found to be 35°for higher albedo and elevation of bPV from the ground as compared to 25° of mPV. An average daily bifacial gain of 35.68% can be achieved in clear sunny day with 90% albedo, tilt angle of 35° and at height of 1.5 m. The maximum specific productions of 192.4 kWh/kWp and 160.6 kWh/kWp are observed in May for bPV and mPV, respectively while the maximum bifacial gain of 21.93% is found in July. [ABSTRACT FROM AUTHOR]

Purpose: To investigate sports compression garment (CG)-induced recovery hemodynamics and their potential impact on subsequent cycling performance.Methods: In a randomized crossover design, 13 physically active men (20.9 ± 1.4 years; 65.9 ± 7.8 kg; 173.3 ± 4.8 cm; peak power output 254.2 ± 27.2 W) underwent 2 experimental trials. During each experimental trial, the subjects performed 20-min fatiguing preload cycling followed by 60-min passive recovery wearing either a sports CG (28.6 ± 9.4 mmHg) or gymnastic pants (CON). A 5-min all-out cycling performance test was subsequently conducted and power output and cadence were recorded. Cardiac output (CO) and stroke volume (SV) were measured using Doppler ultrasound (USCOM®). Heart rate (HR), blood lactate [BLa-], ratings of perceived exertion (RPE), leg muscle soreness (LMS), mean arterial pressure (MAP) and systemic vascular resistance (SVR) were monitored at 5, 15, 30, 45, 60 min during passive recovery.Results: During the subsequent 5-min all-out cycling performance test, power output (215.2 ± 24.0 vs. 210.8 ± 21.5 W, CG vs. CON) and cadence (72.5 ± 3.8 vs. 71.2 ± 4.8 rpm, CG vs. CON) were higher in CG than CON (P < 0.05). SV was higher at 15, 30 and 45 min (P < 0.05), CO was higher at 5 and 45 min (P < 0.05), HR was lower at 15 and 30 min (P < 0.05) and [BLa-] was lower at 5 and 15 min (P < 0.05) during passive recovery, while LMS was lower at all time-points (P < 0.05) compared with CON.Conclusion: Sports CG improves subsequent cycling performance by enhancing hemodynamic responses and attenuating perceived muscle soreness during passive recovery in physically active men. [ABSTRACT FROM AUTHOR]

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In this work, we report a method to enlarge the trapezoidal cantilever-based harvester power by using the high-performance Sc0.2Al0.8N/aluminum nitride (AlN) composite film and introducing symmetrical corners to both sides of the beam. Energy harvesters with variable beam structure and piezoelectric film are designed and evaluated by simulations and experiments. The trapezoid with corners (TWCs) cantilever is verified to improve the output power by a factor of five times when compared with the conventional trapezoidal cantilever without corners. The maximum power density of the ScAlN/AlN-based TWC cantilever harvester is about twice that of the AlN-based harvester, reaching 2.054 mW ⋅ g−2 ⋅ cm−3 at a frequency of 330.25 Hz. The optimization of piezoelectric film and structure can give an inspiration for further improving the performance of cantilever-based energy harvesters. [ABSTRACT FROM AUTHOR]