Peak Power Rate Research Articles

Statistical Analysis of Levelized Round Trip Cost of Grid Scale Electrical Energy Storage in Batteries with Different Chemistries

Electrical energy storage is a crucial component of the clean energy transition for integrating high share of renewable electricity generators into the supply mix. In this study, the round-trip costs of grid scale electrochemical energy storage from 2 up to 24 hours for peak power ratings of 1 MW and 10 MW in lithium-ion LFP, lithium-ion NMC, Pb-acid and vanadium redox flow batteries are compared using their currently projected techno-economic characteristics for year 2030. A statistical approach is used for estimating mean costs and quantifying the uncertainties in these estimates, since many of the techno-commercial features are still evolving and are uncertain. Using Monte Carlo simulations to derive the input parameters, the levelized round trip cost of energy storage is found to vary from Rs 10.73±0.77/kWh(e) to Rs 15.96±1.12/kWh(e) for Li-LFP batteries, Rs 14±1/kWh(e) to Rs 20.3±1.46/kWh(e) for Li-NMC batteries, Rs 19.1±1.39/kWh(e) to Rs 58.3±4.28/kWh(e) for Pb-acid batteries and Rs 18.7±1.37/kWh(e) to Rs 44.2±3.19/kWh(e) for Vanadium redox flow batteries, for the range of input values considered in this study. Through sensitivity analysis and calculation of correlation coefficients, the battery installed capital cost and useful lifetime are found to be the two most influential parameters affecting life cycle electrical energy storage cost.

Conversion of a small size passenger car to hydrogen fueling: simulation of full load performance

Abstract Hydrogen offers a valid choice when considering zero emissions transport. This alternative fuel is well suited for spark ignition (SI) engines and it can be implemented with relatively minor changes in terms of added components. Initial evaluations of feasibility with respect to available space for the fuel tank revealed that it is possible to convert a small size passenger car to hydrogen fueling and maintain a range comparable to the fully electric alternative. Peak power assessment showed that additional boosting was required compared to gasoline operation, close to the limit of compressor surge. As a result, the present study extended the engine speed range so as to evaluate full load performance levels that can be obtained when using hydrogen. 0D/1D simulation was applied for simulating power unit output as well as related control parameters. A dedicated laminar flame speed sub-model was implemented for including fuel chemistry effects. Predicted combustion phasing showed the required changes in ignition timing when switching fuels and revealed that the engine could be operated close to stoichiometry when using hydrogen. A reduction of torque was calculated at low engine speed, even if peak power ratings were practically the same as with gasoline fueling.

Pulsed Ho:YLF laser intra-cavity pumped by a diode-pumped Q-switched Tm:YAP laser.

We reported an intra-cavity pumped Q-switched laser with dual-wavelength synchronous output at 2066.7 nm and 1940nm. Ho:YLF crystal was pumped by a self-Q-switched Tm:YAP laser, which was served as both a gain medium and a saturable absorber simultaneously. For Ho:YLF laser, under 11.4-W incident pump power, a stable pulse laser was achieved at 2066.7 nm with the highest peak power of 69.65 W and the pulse repetition rate of 42.14 kHz. Under the same incident pump power, the highest peak power and pulse repetition rate of Tm:YAP laser were 17.85 W and 50.82 kHz, corresponding to the central wavelength of 1940nm. These results suggested that Q-switching without additional absorber element were effective way to obtain high-efficiency and compact 2.1 µm pulsed laser.

Effects of external limb compression and/or low‐load resistance exercise on post‐activation performance enhancement during countermovement jumps

AbstractThe effects of low‐load resistance exercise combined with external limb compression (ELC) to augment post‐activation performance enhancement during countermovement jumps have yet to be examined. We assessed the separate and combined effects of ELC and sets of low‐load (back squats) resistance exercise (both compared with controls) during conditioning routines, and determine their subsequent neuromechanical consequences during countermovement jumps. On separate days, twenty strength‐trained men completed a familiarization session followed by four experimental trials in a randomized design that included one of the following conditioning routines: passive rest (Control [CON], no occlusion/standing), exercise (sets of low‐intensity resistance exercise [RE] with 30% 1RM, no occlusion/exercise), ELC ([ELC] at 80% of the individual arterial occlusion pressure, occlusion/standing), and combined ELC and exercise ([ELC + RE], occlusion/exercise). Countermovement jump performance (jump height, relative peak power output, vertical impulse, and rate of force development) was assessed at baseline, immediately after, and at the third, sixth, ninth and twelfth minute following each conditioning routine. Compared to baseline, jump height, relative peak power output and vertical impulse values were lower at 0 min for [RE] (−3.5%–8.2%; p ≤ 0.014) and higher at +3 min for [ELC] (+2.0%–3.8%; p ≤ 0.013). Regarding [ELC + RE], values for these three variables were lower at 0 min (−4.8%–8.0%; p < 0.001) but higher at +12 min (+2.9%–5.5%; p < 0.001) versus baseline. In strength‐trained men, using ELC either alone (while standing) or combined with low‐load resistance exercise sets (during back squats) can be a useful way to improve CMJ mechanics. However, the duration and magnitude of post‐activation potentiation performance benefits varied depending on the type of ELC protocol used.

Monitoring laser weld penetration status from the optical signal

Spectrometers have demonstrated their value in laser welding by facilitating the comprehension of welding dynamics and the identification of defects. However, the complex interaction between the laser beam and the material being welded makes it difficult for spectrometers to accurately capture the depth and extent of weld penetration, predominantly because plasma formation during welding interferes. This study presents an innovative approach that integrates laser technology, spectrometers, and advanced data analysis methods to classify and characterize various penetration types in pulse laser welding procedures, with notable computational efficiency. The research entailed the execution of an experiment on a boron steel plate, wherein peak power (1000-1200 kW), pulse duration (2-4 ms), and pulse repetition rate (25-50 Hz) were systematically varied to achieve diverse penetration conditions. Two categories of joints were identified based on their depth of penetration through careful analysis of the collected data. The investigation demonstrated a positive correlation between the depth of weld penetration and the increment of laser energy, with peak power ranging from 1000 kW to 1200 kW. Consequently, an elevation in light intensity was observed related to deeper weld penetration. The information is essential for understanding the relationship between laser energy and weld penetration, highlighting the importance of controlling laser parameters to achieve desired welding results. The spectrums were analyzed using Principal Component Analysis (PCA) to distinguish between different welding conditions. Overlap was observed between data from different weld conditions due to limitations imposed by the restricted dataset. Expanding the sample size can rectify this limitation and improve the accuracy and dependability of analytical outcomes. This study’s results provide valuable insights into optimizing welding parameters and improving understanding of the welding process, specifically in Tailor Weld Blanks. The findings offer potential for improving welding quality and strengthening lightweight components in high-performance industries like aerospace and automotive engineering.

Investigation of mortality rate of Drosophila melanogaster irradiated with nanosecond passively Q-switched microchip laser

Lasers have been widely used for pest control because they are efficient and effective to kill pests. Efficient pest control has been achieved with pulsed lasers, however, there is less investigation of effects of pulse characteristics on the pest mortality. Here, the effects of laser beam diameter, pulse width, peak power, and repetition rate of a compact passively Q-switched microchip laser on the mortality rate of Drosophila melanogaster have been studied. The lethality dosing for 90% mortality rate (LD90) Drosophila melanogaster has been utilized for evaluating the effects of passively Q-switched laser on mortality of insects. The beam diameter comparable to the size of Drosophila melanogaster is effective and economic for killing insects. The energy fluence required for LD90 decreases about 6.5% as pulse width is shortened from 1.5 ns to 850 ps. The energy fluence required for LD90 decreases about one-third as the peak power of passively Q-switched microchip laser increases four times from 6.94 kW to 27.48 kW. The energy fluence required for LD90 decreases dramatically from 16.02 J/cm2 to 12.77 J/cm2 as repetition rate increases from 5.05 kHz to 9.9 kHz and then tends to keep as a constant around 12.7 kHz with further increase of repetition rate. Nanosecond passively Q-switched microchip laser with high peak power and high repetition rate is a promising light source for effective and efficient pest control.

Experimental and numerical demonstration of driver pulse spectral width and phase dependence in near-single-cycle pulse post-compression generation

For many years, light-matter interaction in the strong-field regime has benefited from continuous improvement of femtosecond lasers, in terms of peak power or repetition rate. One of the most current major challenges is the achievement of high-energy, near single-cycle pulses. Such performances are of primary interest in attosecond science for producing intense isolated bursts of extreme ultraviolet light through high-harmonic generation in gases or solids. We present here a detailed experimental and numerical study on a helium filled hollow-core fiber-based post-compression stage. Our measurements highlight the importance of the width and phase of the input spectrum on the spectral broadening, and on the resulting post-compressed pulse. Near Fourier-transform-limited pulses as short as 3.5 fs, carrying a 2.5 mJ energy centered at 750 nm at 1 kHz repetition rate, and leading to a compression factor greater than seven, are demonstrated. The numerical results are in good agreement with the experimental data. Here, spectral broadening is governed by the Kerr effect and the self-steepening on the trailing edge of the guided pulse.

Next generation edge computing: A roadmap to net zero emissions

Multi-access Edge Computing (MEC, formerly, Mobile Edge Computing) offers users of Mobile Devices (MDs) such as smartphones advantages in computational task completion times by offloading to superior but geographically close computing resources. There is a need to make these services more sustainable (energy-efficient) as an initial step towards net zero emissions. We have modelled a zero-latency edge node-MD connection as a single base station linked to a devoted server with the MD transmitting and receiving data via a Wireless Local Area Network (WLAN) with, wherever possible, identifiable real-world power ratings. In this paper, we demonstrate that the total energy usage by the MD and edge node hardware can be markedly less than that of the MD alone in 3 G, 4 G and 5 G WLAN networks. The energy savings, computed as percentages of MD-alone energy usage, are independent of data file size, are greater with computationally more complex tasks, and have a higher MD CPU workload but moderate server CPU workloads. Energy savings are highly dependent on the precise configuration of the base station with server type (peak power rating, the number of CPU cores and the maximum number of jobs processed simultaneously). A 5 G base station has the highest power consumption, but this is offset by much faster WLAN speeds, which can result in energy savings in excess of 90% compared with MD computation alone. We discuss the implications of these results for reducing global electricity use and achieving carbon neutrality to contribute towards net zero emissions.

Analysis and Design of an Integrated Bidirectional Three-Phase AC–DC Resonant Converter

This paper proposes a novel isolated bidirectional AC-DC converter where the front end and primary side of DC-DC isolated converter are merged giving rise to 25&#x0025; fewer devices. Owing to the integrated topology the devices of the proposed converter are naturally soft switched and the size of the filtering components in the AC-DC stage is reduced compared to a low frequency hard switched AC-DC stage. A Space Vector Modulation (SVM) and control technique is proposed for generating switching pulses for DC link voltage control and bidirectional power transfer. A design optimization technique is proposed to mathematically determine the switching frequency of the converter and subsequently, the resonant tank parameters based on the operating conditions, topology, modulation, and the Wide Band Gap (WBG) Silicon Carbide (SiC) device characteristics. The proposed converter and its design approach are validated through prototyping for a scaled-down bidirectional charger for warehouse Electric Vehicles (EVs), and experimental results from two test cases, one with the actual grid with an input ac line (<i>i.e.,</i> 208&#x00A0;V) voltage and second with an AC power supply of input line (<i>i.e.,</i> 400&#x00A0;V) voltage. The former is tested for a peak power rating of 2.5&#x00A0;kW and the later is tested for a 5&#x00A0;kW output power. The switching frequency from the proposed optimization method is determined to be around 130&#x00A0;kHz for both cases. Peak efficiency of 95.3&#x0025; is achieved. The battery voltage varies from 350-600&#x00A0;V.

Semi-Squat Exercises with Varying Levels of Arterial Occlusion Pressure during Blood Flow Restriction Training Induce a Post-Activation Performance Enhancement and Improve Vertical Height Jump in Female Football Players.

Low-load blood flow restriction training (BFRT) has been shown to induce a significant increase in muscle activation. However, low-load BFRT to augment the post-activation performance enhancement (PAPE) has not been previously examined. This study aimed to examine the PAPE of low-intensity semi-squat exercises with varying pressure BFRT on vertical height jump performance. Twelve elite athletes from the Shaanxi Province women's football team volunteered to participate in this study for 4 weeks. Participants completed four testing sessions that included one of the following at random: (1) non-BFRT, (2) 50% arterial occlusion pressure (AOP), (3) 60% AOP, or (4) 70% AOP. Muscle activity of the lower thigh muscles was recorded using electromyography (EMG). Jump height, peak power output (PPO), vertical ground reaction forces (vGRF), and rate of force development (RFD) were recorded for four trials. Two-factor repeated measures analysis of variance (ANOVA) showed that semi-squat with varying pressure BFRT had a significant impact on the measured muscle EMG amplitude and MF value of vastus medialis, vastus lateralis, rectus femoris, and biceps femoris (P < 0.05), and MF value decreased with increasing pressure. Muscle activation (EMG amplitude) did not change further. The EMG amplitude of the gluteus maximus was significantly decreased by semi-squat training with different pressures (P < 0.05), while that of the gluteus maximus muscle was gradually increased by non-BFR with semi-squat training (P > 0.05). The 50% and 60% AOP BFRTs significantly increased jump height, peak power, and force increase rate (RFD) after 5 min and 10 min of rest (P < 0.05). This study further confirmed that low-intensity BFRT can significantly increase lower limb muscle activation, induce PAPE, and improve vertical height jump in female footballers. In addition, 50% AOP continuous BFRT is recommended for warm-up activities.

Table-top optical parametric chirped pulse amplifiers: past and present

The generation of power- and wavelength-scalable few optical cycle pulses remains one of the major challenges in modern laser physics. Over the past decade, the development of table-top optical parametric chirped pulse amplification-based systems was progressing at amazing speed, demonstrating excellent performance characteristics in terms of pulse duration, energy, peak power and repetition rate, which place them at the front line of modern ultrafast laser technology. At present, table-top optical parametric chirped pulse amplifiers comprise a unique class of ultrafast light sources, which currently amplify octave-spanning spectra and produce carrier-envelope phase-stable, few optical cycle pulses with multi-gigawatt to multi-terawatt peak powers and multi-watt average powers, with carrier wavelengths spanning a considerable range of the optical spectrum. This article gives an overview on the state of the art of table-top optical parametric chirped pulse amplifiers, addressing their relevant scientific and technological aspects, and provides a short outlook of practical applications in the growing field of ultrafast science.

High Dose of Acute Normobaric Hypoxia Does Not Adversely Affect Sprint Interval Training, Cognitive Performance and Heart Rate Variability in Males and Females.

Simple SummarySprint interval training (SIT) is a feasible and time-efficient alternative to classical endurance training that has gained popularity among athletes because of its ability to elicit physiological and cardiorespiratory adaptations in a shorter amount of time than traditional endurance training. Further, popular altitude/hypoxic training techniques include intermittent hypoxic training, in which athletes exercise at submaximal levels under simulated hypoxia while living at sea level (normoxia). Hypoxic exercise is likely a more potent stimulant to upregulate muscle factors (e.g., mitochondrial biogenesis, oxidative, and glycolytic enzymes) than similar normoxic exercise. However, SIT in hypoxia may disturb acute performance indices during sprint intervals. Hypoxia may also impair cognitive function. Acute hypoxia may decrease cognitive performance in areas such as memory and executive functioning. Moreover, males and females may have distinct athletic performance responses to SIT and hypoxia. However, to date, there is no study that has investigated the effects of different doses of acute normobaric hypoxia on SIT and cognitive performance, nor has there been research investigating potential sex-based differences.Although preliminary studies suggested sex-related differences in physiological responses to hypoxia, the effects of sex on sprint interval training (SIT) performance in different degrees of hypoxia are largely lacking. The aim of this study was to examine the acute effect of different doses of normobaric hypoxia on SIT performance as well as heart rate variability (HRV) and cognitive performance (CP) in amateur-trained team sport players by comparing potential sex differences. In a randomized, double-blind, crossover design, 26 (13 females) amateur team-sport (football, basketball, handball, rugby) players completed acute SIT (6 × 15 s all-out sprints, separated with 2 min active recovery, against a load equivalent to 9% of body weight) on a cycle ergometer, in one of four conditions: (I) normoxia without a mask (FiO2: 20.9%) (CON); (II) normoxia with a mask (FiO2: 20.9%) (NOR); (III) moderate hypoxia (FiO2: 15.4%) with mask (MHYP); and (IV) high hypoxia (FiO2: 13.4%) with mask (HHYP). Peak (PPO) and mean power output (MPO), HRV, heart rate (HR), CP, capillary lactate (BLa), and ratings of perceived exertion (RPE) pre- and post-SIT were compared between CON, NOR, MHYP and HHYP. There were no significant differences found between trials for PPO (p = 0.55), MPO (p = 0.44), RPE (p = 0.39), HR (p = 0.49), HRV (p > 0.05) and CP (response accuracy: p = 0.92; reaction time: p = 0.24). The changes in MP, PP, RPE, HR, CP and HRV were similar between men and women (all p > 0.05). While BLa was similar (p = 0.10) between MHYP and HHYP trials, it was greater compared to CON (p = 0.01) and NOR (p = 0.01), without a sex-effect. In conclusion, compared to normoxia, hypoxia, and wearing a mask, have no effect on SIT acute responses (other than lactate), including PP, MP, RPE, CP, HR, and cardiac autonomic modulation either in men or women.

Waveform Learning for Next-Generation Wireless Communication Systems

We propose a learning-based method for the joint design of a transmit and receive filter, the constellation geometry and associated bit labeling, as well as a neural network (NN)-based detector. The method maximizes an achievable information rate, while simultaneously satisfying constraints on the adjacent channel leakage ratio (ACLR) and peak-to-average power ratio (PAPR). This allows control of the tradeoff between spectral containment, peak power, and communication rate. Evaluation on an additive white Gaussian noise (AWGN) channel shows significant reduction of ACLR and PAPR compared to a conventional baseline relying on quadrature amplitude modulation (QAM) and root-raised-cosine (RRC), without significant loss of information rate. When considering a 3rd Generation Partnership Project (3GPP) multipath channel, the learned waveform and neural receiver enable competitive or higher rates than an orthogonal frequency division multiplexing (OFDM) baseline, while reducing the ACLR by <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mathrm {10~ \text {dB}}$ </tex-math></inline-formula> and the PAPR by <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mathrm {2~ \text {dB}}$ </tex-math></inline-formula> . The proposed method incurs no additional complexity on the transmitter side and might be an attractive tool for waveform design of beyond-5G systems.

In-band pumped 2 μm pulsed laser with dual-wavelength synchronous output

We reported an in-band pumped Q-switched laser with dual-wavelength synchronous output at 2067.1 nm and 1885.7 nm. Ho:YLF crystal, which was pumped by Tm:YLF laser, was served as both a gain medium and a saturable absorber simultaneously. For Ho:YLF laser, under 16.02 W incident pump power, a stable pulse laser was achieved at 2067.1 nm with the highest peak power of 21.71 W and the pulse repetition rate of 70.62 kHz. Under the same incident pump power, the highest peak power and pulse repetition rate of Tm:YLF laser were 44.05 W and 71.56 kHz corresponding to the central wavelength of 1881.5 nm. These results suggested that in-band pumping was an effective way to obtain high efficiency dual-wavelength synchronous pulsed laser.

Supercontinuum generation of gold coated side-polished fiber based-mode-locked pulse

A supercontinuum (SC) generation is produced by mode-locked pulses incorporating gold-coated side-polished as saturable absorber (SA) inserted into a 50 m high nonlinear fiber (HNLF) in a 2.81 m single ring length cavity, with 0.5 m of erbium-doped-fiber (EDF). The side-polished fiber (SPF) is coated with a gold thin film using DC magnetron sputtering that acts as a saturable absorber (SA). Gold-SPF is inserted in the laser cavity to produce a passively mode-locked fiber laser, creating pulses with pulse energy, peak power, and repetition rate of 7.55 pJ, 13.25 W, and 38.73 MHz, respectively. This pulse is then injected into a 1.5 ps/nm.km dispersion of HNLF with a 50 m, giving an SC spectral bandwidth beyond 1700 nm from 1407.1 nm, with an FWHM pulse width of 570 fs.

Specific Fitness Profiles through Analysis of the Correlation between Anaerobic Power, Maximal Strength, and Isokinetic Strength in Korean National Snowboarders

Purpose: We examined the associations between anaerobic power, maximal strength, and isokinetic strength in Korean National snowboarders. Methods: We examined cross-sectional associations between isokinetic trunk strength in 89 Korean National snowboarders (mean age: 22.17 ± 4.82 years). The main outcome measures were the Wingate anaerobic power test, maximal strength test, and isokinetic knee strength test. Results: Isokinetic trunk strength was correlated with anaerobic power (lower average power, peak power, and power-drop rate). Further, trunk strength flexion and extension were significantly associated with maximal strength (knee strength and one-repetition maximum). Conclusions: The Korean national snowboarders’ anaerobic capacity and maximal muscle strength measurements were positively associated with their isokinetic trunk strength. Further research is needed to elucidate the core balance and muscle-growth mechanisms underlying this association; ideally, future studies will involve exercise and treatment interventions to identify causal relationships.

Descriptive and Kinetic Analysis of Two Different Vertical Jump Tests Among Youth and Adolescent Male Basketball Athletes Using a Supervised Machine Learning Approach.

Gillett, J, De Witt, J, Stahl, CA, Martinez, D, and Dawes, JJ. Descriptive and kinetic analysis of two different vertical jump tests among youth and adolescent male basketball athletes using a supervised machine learning approach. J Strength Cond Res 35(10): 2762-2768, 2021-The countermovement jump (CMJ) is a functional movement in basketball and is also frequently used as an assessment of lower-body power. The CMJ can be performed in a variety of manners, and multiple variables can be extracted, and calculated, from the ground reaction force (GRF) time curve. The purpose of this article is to present kinematic and kinetic data collected from adolescent male basketball players during performance of the CMJ with hands on hips (HOH) or with an arm swing while reaching overhead to a target (i.e., vertical jump reach [VJR]). This study also sought to determine the effectiveness of a machine learning algorithm to identify the most important features that relate to jump height. Bilateral GRF data were collected on 89 right-handed male basketball athletes (age: 13.19 ± 0.72 year old, mass: 60.44 ± 13.35 kg, standing reach height: 228.49 ± 16.79 cm) using force platforms (Forcedecks, Vald Performance, Newstead, Queensland, Australia) and their associated software. Fifty-six bilateral kinematic and kinetic variables from each condition were analyzed using supervised machine learning to identify the top 10 important features to predict jump height in each condition, and to predict VJR height using HOH data. Vertical center of mass flight height was greater during VJR trials than during HOH trials (38.9 ± 6.8 cm vs. 32.6 ± 5.5 cm, respectively). The only common predictor variables between the conditions were concentric impulse and peak power. HOH jump data were able to predict VJR height with a mean error of 7.13 cm. These data suggest that important force platform data relating to jump height differ depending on test condition, and that data from CMJ performed with HOH, particularly peak power, concentric impulse, and concentric rate of power development, can be used to predict jump height during functional performance.

Adding hydrogen to fuel gas to improve energy performance of gas-turbine plants

The study aims to calculate the technical and economic efficiency of adding hydrogen to natural gas to improve the energy characteristic of the fuel in gas-turbine plants during long-term gas field operations. Mathematical modelling techniques in the CAS CFDPT (computer-aided system for computational fluid dynamics of power turbomachinery) program were used to develop a mathematical model of the General Electric 6FA gas turbine engine. It was shown that a decrease in the calorific value of the fuel leads to an increase in fuel consumption by 11% and the amount of CO2, NO2 in the turbine exhaust gas. It was determined that, during the freezing season and peak power rating operations, the turbine power is limited by the fuel system capacity (its maximum value amounted to 5.04 kg/s). It was shown that energy characteristics can be improved by adding hydrogen to the feed natural gas. Energy efficiency was calculated at different fuel components (hydrogen and natural gas) ratios at variable-load operation in the range between 75 and 85 MW. Instant fuel gas flow amounted to 5.04 kg/s (with 4.5% hydrogen and 95.5% natural gas in the feed fuel) at 85 MW. Due to its high cost, the use of hydrogen is only advisable in peak power rating operations to reach the maximum capacity of the gas-turbine plant. The proposed method of adding 4.5% hydrogen to fuel gas allows the maximum fuel consumption to be maintained at a rate of 5.04 kg/s to reach the topping power of 85 MW. When using this method, there are no limitations on the maximum and peak capacity of the gas-turbine plant.

Differences in Kinetics during One- and Two-Leg Hang Power Clean.

The purpose of this study was to quantify the kinetics per leg during the one- and two-leg hang power clean using various loads. Nine male track and field athletes performed the one- and two-leg hang power clean on a force platform. The estimated one-repetition maximum was used for the one-leg hang power clean (OHPC), and the one-repetition maximum was used for the two-leg hang power clean (THPC). The loads used were 30%, 60%, and 90% during both trials. We calculated peak power, peak force, and peak rate of force development during the pull phase from the force-time data. The peak power and the peak force for all loads during the OHPC were statistically greater than during the THPC. The peak rates of force development at 60% and 90% during the OHPC were statistically greater than during the THPC. Additionally, the peak power at 90% was significantly less than at 60% during the THPC. These findings suggest that the OHPC at loads of 60% and 90% is a weightlifting exercise that exhibits greater explosive force and power development characteristics than the THPC.

Energy pathway contributions during 60-second upper-body Wingate test in Greco-Roman wrestlers: intermittent versus single forms

ABSTRACT This study aimed to investigate the energy pathway contributions and physiological and performance responses between a 10 × 6-second intermittent sprint test (IST) and a 60-second single maximal test (SMT). Seventeen highly trained male Greco-Roman wrestlers participated in this study. Participants completed the 60-second upper-body Wingate tests, both intermittent and single forms. The contributions of the oxidative, glycolytic, and ATP-PCr pathways were estimated using mathematical methods based on lactate values and oxygen consumption kinetics of rest, exercise, and recovery phases. The main findings indicated that total energy expenditure (TEE) and the contribution of oxidative, glycolytic, and ATP-PCr pathways were 514 kJ, 45%, 11%, and 44% for IST (overall: sprints + rest intervals); 333 kJ, 14%, 17%, and 69% for IST (sprints only); and 159 kJ, 31%, 38%, and 31% for SMT, respectively. TEE and ATP-PCR pathway contributions were higher in the IST (both overall and sprint only), whereas glycolytic pathway contribution and delta lactate were higher in the SMT. Absolute oxidative contribution was similar, but relative oxidative contribution was higher in the SMT. Additionally, mean power was higher in the IST than SMT, whereas peak power, peak and mean heart rate, and ratings of perceived exertion were similar.