Peak Power Values Research Articles

Reliability of Gallon-Jug Shelf-Transfer Power Equations in Older Women.

Ly, A, Strand, KL, Courtney, KJ, Barry, SS, Liscano, JA, Trebotich, TL, Martin-Diala, C, Martin, E, and Signorile, JF. Reliability of gallon-jug shelf-transfer test power equations in older women. J Strength Cond Res 37(5): 1124-1130, 2023-This study examined the test-retest reliability of the gallon-jug shelf-transfer (GJST) test as a measure of upper-body functional power in older women. Although the validity of the predictive equations for power during the GJST test has been established, for the test to be viable in either a laboratory or clinical environment, between-day and within-day reliability must be established. Thirty-four independently living older women (mean ± SD : 75.0 ± 6.4 years) performed 2 sets of 3 repetitions of the GJST test on 2 days separated by at least 48 hours. Using the established predictive equations, the values for peak power and average power were then computed. Statistical analyses to assess reliability included intraclass correlation coefficient, coefficient of variation (CV), SEM , minimal detectable change (MDC), and Cronbach's α values. Furthermore, Bland-Altman plots evaluated the agreement between the tests. Intraclass correlation coefficient (>0.91, p < 0 001), CV (<8.1%), SEM (<5.94 W), MDC (<14 W), and Cronbach's α (>0.95) indicated excellent reliability. The lines of equality for all Bland-Altman plots fell within the 95% confidence interval of the mean difference, implying that there were no significant differences between tests. Furthermore, bias values were small (<11.15 W), and the limits of agreement (LOA) were within an acceptable range. Based on our statistical analyses, the GJST test is a highly reliable assessment for determining object transfer power for healthy older women.

Supercontinuum generation in chalcogenide photonic crystal fiber infiltrated with liquid

Chalcogenide fibers have attracted much attention for multi-octave spanning supercontinuum generation in the mid-infrared range. However, readily optimizing the dispersion characteristics as well as other mode properties is still problematic because it is difficult to fabricate chalcogenide fibers with sophisticated structures. In this work, we numerically investigate the liquid infiltration as a post-processing method to optimize the dispersion shapes, so that the nonlinear dynamics and spectro-temporal properties of supercontinuum generation are efficiently controlled. In particular, water, carbon disulfide (CS2), carbon tetrachloride (CCl4), and bromoform (CHBr3) are selected to fill into all cladding air holes of As38Se62 fibers for dispersion engineering. By pumping a femtosecond laser at 4.5 μm, pulse duration of 250 fs, and pulse energy of 0.1 nJ (peak power of 0.4 kW), the unfilled and CCl4-filled fibers provide soliton-induced supercontinuum generation with a spectral bandwidth of 2.5–6.5 μm and 2.0–5.5 μm, respectively. Whilst, CHBr3-filled fiber offers all-normal dispersion supercontinuum generation with high coherence and spectral bandwidth of 2.2–5.2 μm. In contrast, unfortunately, CS2 and water-filled fibers have complex dispersion shapes and provide narrow bandwidth supercontinua. We also thoroughly numerically investigate the tapered fibers, which assure both high coupling efficiency with laser sources and high nonlinearity, for broad mid-infrared supercontinuum generation. The results point out that liquid-filled tapered fibers can provide both anomalous and all-normal dispersion SC generation with an octave-spanning bandwidth via the same value of input peak power (0.4 kW). With a large core diameter (12 μm) at the input and output fiber ends, the tapered fibers have a potential to couple with high-power laser pulses without fiber damage, therefore, they can provide supercontinuum spectra with broad bandwidth and high spectral power density for practical applications in sensing, gas detection, and LIDAR.

Design of Bi2Te3-based thermoelectric generator in a widely applicable system

A Bi2Te3-based thermoelectric generator (TEG) system cooled by heat radiation fin (HRF) applies to most scenarios of low-temperature power generation and waste heat recovery, while the high performance of the TEG system requires the precise design of the structure. Here we developed a theoretical model to simulate the thermal-electric coupling of the TEG system and analyzed the Bi2Te3-based TEG system with the aid of numerical and experimental methods. Results show that the increase in height of TEG not only improves the conversion efficiency but leads to a peak value of output power, which is much different from the traditional view that the output power solely decreases with the increase of height of TEG. Compared to the thickness of the fin, the height of the fin plays an essential role in optimizing the performance of TEG. By adding an electrical fan to improve the heat exchange coefficient, the net output power is doubled and the net conversion efficiency is improved by more than 80%. Besides, the structure of the TEG system is designed for different material parameters via the theoretical method. We anticipate that our results will guide the design and optimization of the TEG system.

Changes in the Electrophysical Parameters of Nanomodified Elastomers Caused by Electric Current’s Passage

The development of reliable and effective functional materials that can be used in various technological fields and environmental conditions is one of the goals of modern nanotechnology. Heating elements' manufacturing requires understanding the laws of heat transfer under conditions of different supply voltages, as this expands the possibilities of such materials' application. Elastomers based on silicon-organic compounds and polyurethane modified with multi-walled carbon nanotubes (MWCNTs) were studied at various concentrations of Ni/MgO or Co-Mo/MgO and voltages (220, 250, and 300 V). It was found that an increase in voltage from 220 to 300 V leads to an initial increase in specific power on one-third followed by a subsequent decrease in a specific power when switched on again to 220 V (for -40 °C) of up to ~44%. In turn, for a polyurethane matrix, an increase in voltage to 300 V leads to an initial peak power value of ~15% and a decrease in power when switched on again by 220 V (for -40 °C) to ~36% (Ni/MgO -MWCNT). The conducted studies have shown that the use of a polyurethane matrix reduces power degradation (associated with voltage surges above 220 V) by 2.59% for Ni/MgO-based MWCNT and by 10.42% for Co-Mo/MgO. This is due to the better heat resistance of polyurethane and the structural features of the polymer and the MWCNT. The current studies allow us to take the next step in the development of functional materials for electric heating and demonstrate the safety of using heaters at a higher voltage of up to 300 V, which does not lead to their ignition, but only causes changes in electrophysical parameters.

Effect of Music and Lemon Aroma on Anaerobic Power and Balance of Athletes After Exhausting Activity

Background: The aim of this study was to investigate the effect of lemon aroma (LA) and music on anaerobic power and balance in athletes following sporting activity. Recognizing the potential influence of sensory stimuli on performance, we sought to contribute valuable insights into optimizing recovery strategies for athletes. Objectives: The primary objective was to assess the effects of LA and music on anaerobic power and balance, employing a comprehensive set of physical fitness factors. Methods: Twelve male amateur athletes were randomly included in our study. These individuals were given LA, music, and with no supplementation (control) for 72 hours, followed by a standardized recovery phase using a Monarch ergometer, and lactic acid levels were measured after the intervention to assess the physiological effect. Balance analysis covering both static and dynamic conditions was performed using a specialized balance machine. Isometric dynamometer measurements and detailed assessments of Sargent's jumping performance were performed to analyze physical fitness factors. Results: Significant differences were observed in balance parameters, with both static balance (SB) and dynamic balance (DB) registering higher values in the control time (P = 0.006; P &lt; 0.001, respectively). Lemon aroma exposure resulted in the highest values for peak power (PP) and relative PP (RPP) (P &lt; 0.001; P &lt; 0.001, respectively). Conversely, in the control time exhibited the lowest values for relative anaerobic power (RAP) and vertical jump (VJ). Conclusions: The findings suggest a positive influence of stimulating aroma (lemon) and music elements on sportive performance. Lemon aroma was associated with enhanced anaerobic power, while the control group exhibited superior balance outcomes. These results underscore the potential benefits of incorporating sensory interventions into athletes' recovery protocols for optimized performance.

Renewable Energy Communities in Islands: A Maltese Case Study

Renewable energy communities are considered as key elements for transforming the present fossil fuel-based energy systems of islands into renewable-based energy systems. This study shows how renewable energy communities can be deployed in the Maltese context to achieve higher penetration of residential-scale photovoltaic systems. Case studies for five renewable energy communities in the Maltese LV distribution network have been analyzed in detail. A novel community battery energy storage sizing strategy was proposed to determine the optimal storage capacity at each energy community. The main objective of the community battery storage in each REC is to minimize the reverse power injection in the grid (minimize the total reverse energy and reverse peak power values), as well as to reduce the peak evening electricity demand. The optimal sizes for communal BESSs were determined to be of 57 kWh (EC 1), 55 kWh (EC 2), 31 kWh (EC 3), 37 kWh (EC 4) and 10 kWh (EC 5), respectively. The community storage systems were observed to reduce the overall impact of all five energy communities on the grid infrastructure. Power system simulations were performed for a typical spring day to evaluate the impact of communal BESS placement on the node voltages for all five energy communities. The results showed that the community storage was more effective at reducing the node rms voltage magnitudes when deployed at the end of the respective energy communities, rather than at the beginning of the community. During peak generation hours, reductions of up to 0.48% in the node rms voltage magnitudes were observed. This contrasts with reductions of only 0.19% when the community storage was deployed at the beginning of the energy communities.

Trade-Off Between Maximal Power Output and Fatigue Resistance of the Knee Extensors for Older Men.

This study investigated associations of fatigue resistance determined by an exercise-induced decrease in neuromuscular power with prefatigue neuromuscular strength and power of the knee extensors in 31 older men (65-88 years). A fatigue task consisted of 50 consecutive maximal effort isotonic knee extensions (resistance: 20% of prefatigue isometric maximal voluntary contraction torque) over a 70° range of motion. The average of the peak power values calculated from the 46th to 50th contractions during the fatigue task was normalized to the prefatigue peak power value, which was defined as neuromuscular fatigue resistance. Neuromuscular fatigue resistance was negatively associated with prefatigue maximal power output (r = -.530) but not with prefatigue maximal voluntary contraction torque (r = -.252). This result highlights a trade-off between prefatigue maximal power output and neuromuscular fatigue resistance, implying that an improvement in maximal power output might have a negative impact on neuromuscular fatigue resistance.

Flat Multi-Wavelength Brillouin Erbium-Doped Fiber Laser Based on a Sagnac Loop for High-Sensitivity Sensor.

We have demonstrated the use of a flat multi-wavelength Brillouin erbium-doped fiber laser (MWBEFL) based on a Sagnac loop with an unpumped erbium-doped fiber (Un-EDF) as a high-sensitivity sensor. A Sagnac loop with a Un-EDF was used as power equalizer to achieve multi-wavelength power flatness by adjusting the birefringence beat length properly. In the experiments, the best result obtained in terms of Brillouin Stokes lines and output power flatness was ±0.315 dB and the optical signal-to-noise ratio (OSNR) was 18.97 dB within a 33 nm bandwidth range from 1532.0 nm to 1565.0 nm. The flatness of the 33 nm bandwidth range varied from ±0.315 dB to ±1.38 dB and the average OSNR was about 17.51 dB. The peak power values of Brillouin Stokes lines observed under different wavelengths were extremely close and their range of fluctuation was about ±0.37 dB. These experimental results were close to our previous experimental values obtained using a passive Sagnac loop with a Un-EDF. The flat range covering almost the entire C-band has broad application prospects in high-sensitivity distributed optical fiber sensing and wavelength-division multiplexing.

Half-Squat and Jump Squat Exercises Performed Across a Range of Loads: Differences in Mechanical Outputs and Strength Deficits.

Loturco, I, McGuigan, MR, Freitas, TT, Bishop, C, Zabaloy, S, Mercer, VP, Moura, TBMA, Arruda, AFS, Ramos, MS, Pereira, LA, and Pareja-Blanco, F. Half-squat and jump squat exercises performed across a range of loads: differences in mechanical outputs and strength deficits. J Strength Cond Res 37(5): 1052-1056, 2023-The aim of this study was to compare the peak force (PF), peak power (PP), and peak velocity (PV) outputs produced during half-squat (HS) and jump squat (JS) exercises executed at 20, 40, 60, and 80% of 1 repetition maximum (1RM) in the HS (HS 1RM) and to compute and compare the strength deficit (SDef) achieved in these exercises across these loads. Twenty-four national rugby union players (age: 25.7 ± 3.6 years) performed HS 1RM and a progressive loading test in the HS and JS exercises. The PF, PP, and PV values were obtained in all loads for both exercises, and the SDef was calculated as the percentage difference between the PF at distinct relative intensities and the PF at HS 1RM. The differences in HS and JS variables were determined using an analysis of variance with repeated measures. Higher PF, PP, and PV outputs were generated in the JS in comparison with the HS exercise ( p < 0.05); moreover, the SDef magnitudes were significantly lower in the JS ( p < 0.01), for all loading conditions. Importantly, the differences in SDef, and as a consequence, PF, PP, and PV decreased progressively with increasing load. Overall, the loaded JS exhibited increased levels of PF, PP, and PV and reduced levels of SDef when compared to the traditional HS performed across a range of loads. The JS is indicated to reduce the SDef and improve the athletes' ability to apply force at higher velocities. Nevertheless, with heavier loads (i.e., ≥80% HS 1RM), its potential advantages and effectiveness may be seriously compromised.

Nonlinear dynamics of beam self-cleaning on LP11 mode in multimode fibers.

We investigate the modal energy flow of the femtosecond-pulsed beam self-cleaning on LP11 mode with the influence of different factors such as the initial fraction of LP11 mode, initial peak power, distribution of high-order modes and the numerical aperture of the fiber. It is interesting that there is a critical value of the initial peak power, Pcr, which is the watershed, not only in the quantitatively dominant transverse mode converting from LP11 mode to LP01 mode, but also in the behavior of HOMs of the transition from Attractor to chaos. Our simulation results may provide a novel perspective to understanding the beam self-cleaning on LP11 mode.

Sustainable energy development technique of vertical axis wind turbine with variable swept area – An experimental investigation

The vertical axis wind turbine is one of the most attractive propulsion systems for sustainable energy generation around the globe. The performance of a vertical axis wind turbine is greatly dependent on wind speed, blade set angle and more importantly the rotational speed. The effective utilization of wind speed and rotational speed on power generation would be enhanced by the improvement of energy capturing capability. Therefore, an attempt has been made to develop the vertical axis wind turbine with a variable swept area of blades to enhance the torque and power output over a wide range of rotational speeds and set angles. In the first phase, the wind turbine is designed with flexibility in blade set angles through modification on the swept area and the developed wind turbine has been subjected to various wind speeds and rotational speeds in a wind tunnel. The experimental results revealed that the torque and power are increased with an increase in wind speed and rotational speeds under blade set angle of 30° to 120°. The peak torque and power have been attained at the average speed of the turbine and it has been eventually increased for a higher blade set angle. For constant set angle, the performance characteristics are also improved due to the enhancement in energy capturing ability of wind turbine at the variable swept area. Furthermore, torque and power coefficient are evident in a similar pattern at all wind speeds and rotational speeds under different tip speed ratios. The maximum torque coefficient would be around 0.3 for the tip speed ratio of 0.2–0.3 and the attainment of the peak value of power and torque coefficient has been shifted towards higher speed due to the improvement in blade dimensions. Thus, it is revealed that the vertical axis wind turbine with enhanced swept blade area would be an attractive propulsion system for sustainable energy generation.

Propagation properties of cosh-Airy beams in an inhomogeneous medium with Gaussian PT-symmetric potentials

Abstract We numerically investigate and statistically analyze the impact of medium parameters (modulation depth P, modulation factor ω, and gain/loss strength W 0) and beam parameters (truncation coefficient a and distribution factor χ 0) on the propagation characteristics of a cosh-Airy beam in the Gaussian parity-time (PT)-symmetric potential. It is demonstrated that the main lobe of a cosh-Airy beam is captured as a soliton, which varies periodically during propagation. The residual beam self-accelerates along a parabolic trajectory due to the self-healing property. With increment in P, the period of a trapped soliton decreases almost monotonically, while the peak power of a trapped soliton increases monotonically. With the increase in ω or decrease in the absolute value of W 0, the period and peak power of a trapped soliton decrease rapidly and then almost remain unchanged. Moreover, it is indicated that the period of a trapped soliton remains basically unchanged no matter a and χ 0 increase or decrease. The peak power of a trapped soliton increases with increment of a, but the peak power of a trapped soliton stays relatively constant irrespective of variation in χ 0.

Effectiveness of Warm-Up Exercises with Tissue Flossing in Increasing Muscle Strength.

Tissue flossing is an increasingly popular method in physiotherapy and sports. There is a belief that tissue flossing can improve range of motion and muscle strength, shorten muscle recovery time, and reduce the risk of injury. The aim of this study was to analyse the effectiveness of tissue flossing for immediately improving muscle strength in recreational athletes when it is performed during warm-up. All participants were randomly assigned to either an experimental group (n = 36) or a control group (n = 34) using a random number generator. The experimental group (n = 36) performed an intervention comprising exercises with muscle tissue flossing and exercises without flossing. The control group (n = 30) performed the same protocol without a floss band. Muscle strength was measured for knee flexion end extension at three speeds (60, 120, and 180 °/s) 3 times. Analysed parameters include peak torque, work, and power related to body weight, flexors–extensors ratio, and time to peak torque. There were no significant changes in the muscle strength parameters from before to after the warm-up in either group (p > 0.05). Significantly lower values of peak torque, work, and power were observed in the experimental group during the warm-up with the floss band applied to muscles (p < 0.05). No clinically significant changes in time to peak torque or flexors–extensors ratio were observed. A single application of flossing does not improve muscle strength or power and can even reduce individuals’ maximum muscle strength capabilities.

Association of Gene Variants for Mechanical and Metabolic Muscle Quality with Cardiorespiratory and Muscular Variables Related to Performance in Skiing Athletes.

Background: Skiing is a popular outdoor sport posing different requirements on musculoskeletal and cardiorespiratory function to excel in competition. The extent to which genotypic features contribute to the development of performance with years of ski-specific training remains to be elucidated. We therefore tested whether prominent polymorphisms in genes for angiotensin converting enzyme (ACE-I/D, rs1799752), tenascin-C (TNC, rs2104772), actinin-3 (ACTN3, rs1815739) and PTK2 (rs7460 and rs7843014) are associated with the differentiation of cellular hallmarks of muscle metabolism and contraction in high level skiers. Material & Methods: Forty-three skiers of a world-leading national ski team performed exhaustive cardiopulmonary exercise testing as well as isokinetic strength testing for single contractions, whereby 230 cardiopulmonary measurements were performed in the period from 2015–2018. A total of 168 and 62 data measurements were from the Alpine and Nordic skiing squads, respectively. Ninety-five and one hundred thirty-five measurements, respectively, were from male and female athletes. The average (±SD) age was 21.5 ± 3.0 years, height 174.0 ± 8.7 cm, and weight 71.0 ± 10.9 kg for the analysed skiers. Furthermore, all skiers were analysed concerning their genotype ACE-I/D, Tenascin C, ACTN3, PTK2. Results: The genotype distribution deviated from Hardy–Weinberg equilibrium for the ACTN3 genotype, where rs1815739-TT genotypes (corresponding to the nonsense mutation) were overrepresented in world-class skiers, indicating a slow muscle fibre phenotype. Furthermore, the heterozygous rs2104772-AT genotypes of TNC also demonstrated the best scaled peak power output values during ramp exercise to exhaustion. The highest values under maximum performance for heart rate were associated with the rs1799752-II and rs1815739-CC genotypes. The lowest values for peak power of single contractions were achieved for rs1815739-CC, rs1799752-II and rs7843014-CT genotypes. The skiing discipline demonstrated a main influence on cardiorespiratory parameters but did not further interact with genotype-associated variability in performance. Discussion: Classically, it is pointed out that muscles of, for example, alpine skiers do not possess a distinct fibre type composition, but that skiers tend to have a preponderance of slow-twitch fibres. Consequently, our findings of an overrepresentation of ACTN3-TT genotypes in a highly selective sample of elite world class skiers support the potential superiority of a slow fibre type distribution. Conclusions: We suggest that one competitive advantage that results from a slow, typically fatigue-resistant fibre type distribution might be that performance during intense training days is better preserved, whereby simply a higher technical training volume can be performed, yielding to a competitive advantage.

Experimental Test of Ignition Timing with Programable CDI on Performance Single Cylinder Otto Engine

&lt;span class="fontstyle0"&gt;Ignition timing is sparking from the spark plug based on the ignition angle during the compression stroke in the combustion chamber relative to the piston position and the crankshaft angular speed. Adjusting the ignition angle is one method to optimize the combustion process in the engine. An optimal combustion process can improve engine performance and reduce fuel consumption. This study investigates optimal data from ignition angle changes using a programmable CDI. The test was performed on a single-cylinder fourstroke Otto engine with standard ignition angle variations, +3°, +6°, and +9° before TDC. The test results show that torque and power have increased while brake-specific fuel consumption has decreased. Optimal data acquisition at ignition angle of +9° with peak torque value of 6.91 Nm and peak power value of 4.80 kW, while the lowest value of specific fuel consumption is 0.234 kg/kWh, and the highest value of thermal efficiency is 36 %. From this study, it was concluded that the ignition timing could affect the engine performance.&lt;/span&gt;

Generation of Parabolic pulse by nonlinear pulse reshaping inside a Silicon on Insulator (SOI) Waveguide

In recent times, silicon photonics attracts a lot of attraction of researchers. It is the technology that converts many functions of the circuit on the thumb-size chip. Nowadays, various types of technology platforms are being used to design photonic integrated circuits using various materials such as high index glass, semiconductors, polymers, and silicon. In our work, we have used silicon to design rectangular silicon on Insulator (SOI) buried waveguide. This type of waveguide has shown great potential in the field of pulse reshaping. We have used the effective index method for the calculation of group velocity dispersion and nonlinearity. Though the two-photon absorption and free-carrier generation contribute significantly to loss parameters, the highly nonlinear buried waveguide is found to be capable of reshaping super-Gaussian pulse input into a parabolic shape. Moreover, the values of input chirp, pulse width, and peak power are further optimized for the generation of a high-quality parabolic pulse at shorter lengths. The length required for pulse reshaping is much less when compared to optical fibers. Thus, our design waveguide has potential in the domain of pulse generation, signal processing, and many more.

Load-power relationship in older adults: The influence of maximal mean and peak power values and their associations with lower and upper-limb functional capacity.

Identifying the relative loads (%1RM) that maximize power output (Pmax-load) in resistance exercises can help design interventions to optimize muscle power in older adults. Moreover, examining the maximal mean power (MPmax) and peak power (PPmax) values (Watts) would allow an understanding of their differences and associations with functionality markers in older adults. Therefore, this research aimed to 1) analyze the load-mean and peak power relationships in the leg press and chest press in older adults, 2) examine the differences between mean Pmax-load (MPmax-load) and peak Pmax-load (PPmax-load) within resistance exercises, 3) identify the differences between resistance exercises in MPmax-load and PPmax-load, and 4) explore the associations between MPmax and PPmax in the leg press and chest press with functional capacity indicators. Thirty-two older adults (79.3 ± 7.3 years) performed the following tests: medicine ball throw (MBT), five-repetition sit-to-stand (STS), 10-m walking (10 W), and a progressive loading test in the leg press and chest press. Quadratic regressions analyzed 1) the load-mean and peak power relationships and identified the MPmax-load, MPmax, PPmax-load, and PPmax in both exercises, 2) the associations between MPmax and PPmax in the chest press with MBT, and 3) the associations between MPmax and PPmax in the leg press with STSpower and 10Wvelocity. In the leg press, the MPmax-load was ∼66% 1RM, and the PPmax-load was ∼62% 1RM, both for women and men (p > 0.05). In the chest press, the MPmax-load was ∼62% 1RM, and the PPmax-load was ∼56% 1RM, both for women and men (p > 0.05). There were differences between MPmax-load and PPmax-load within exercises (p < 0.01) and differences between exercises in MPmax-load and PPmax-load (p < 0.01). The MPmax and PPmax in the chest press explained ∼48% and ∼52% of the MBT-1 kg and MBT-3 kg variance, respectively. In the leg press, the MPmax and PPmax explained ∼59% of STSpower variance; however, both variables could not explain the 10Wvelocity performance (r 2 ∼ 0.02). This study shows that the Pmax-load is similar between sexes, is resistance exercise-specific, and varies within exercises depending on the mechanical power variable used in older adults. Furthermore, this research demonstrates the influence of the MBT as an upper-limb power marker in older adults.

Reliability Of The Gallon Jug Shelf Transfer Test: An Object Transfer Test For Older Individuals

The declines in power during the performance of daily activities are associated with a reduced ability to perform basic and instrumented activities of daily living. The Gallon Jug Shelf Transfer Test (GJST) is a validated upper body muscle function test that can be used to quantify power and monitor functional changes in older persons. PURPOSE: Although the validity of the GJST and its predictive equations for transfer power has been established, the reliabilities of the GJST power equations need to be assessed if they are to be used in clinical or research environments. Therefore, this study aims to evaluate the intra-rater and test-retest reliabilities of the GJST. METHODS: 40 independently-living seniors between the ages of 50-90 performed two sets of 3 repetitions of the GJST separated by 48 hours on Day 1 and the same pattern of testing on Day 2. Using the predictive equations developed in our laboratory, the values for peak power (PP) and average power (AP) were then computed. Statistical analyses to assess various forms of reliability included calculating intraclass correlation coefficient (ICC), confidence intervals (CI), coefficient of variation (CV), standard error of measurement (SEM), and minimal detectable change (MDC) values. Further Bland-Altman plots evaluate the agreement among the tests. RESULTS: Intraclass correlation coefficients (ICC > .90, p < .0001), Cronbach’s alpha, and Bland-Altman analyses of between-trial and between-day test-retest reliability for peak and average power indicated excellent reliability. Cronbach’s α and ICC for trial 2 (days 1 & 2) and day 2 (trials 1 & 2) slightly increased, compared to trial 1 (days 1 & 2), and day 1 (trials 1 & 2). The lines of equality for all Bland-Altman plots, whether showing between-day or between-trial comparisons, fell within the LOA showing that there was no significance for the difference scores (p < .05). Bias, SD, LOA, CV, SEM, and MDC, slightly decreased for trial 2 (days 1 & 2) and day 2 (trials 1 & 2) compared to trial 1 (days 1 & 2), and day 1 (trials 1 & 2) for peak and average power. CONCLUSIONS: Based on our statistical analyses, the GJST has proven to be a safe, easy to administer, ADL- specific, and highly reliable assessment for determining upper body power for healthy older adults.

Improving the Utilization of Regenerative Energy and Shaving Power Peaks by Railway Timetable Adjustment

Employing regenerative braking in trains contributes to reducing the amount of energy used, especially when applied to commuter trains and to those used on very dense suburban networks. This paper presents a method to fine-tune the periodic timetable to improve the utilization of regenerative energy and to shave power peaks while maintaining the structure and robustness of the original timetable. First, a mixed-integer linear programming model based on the periodic event scheduling framework is proposed. A set of feasible timetables is determined and optimized with the aim of increasing synchronized acceleration and braking events at the same station, and maintaining the timetable robustness at the specified level. Next, a local search algorithm is developed to optimize the timetable such that the power peak value is minimized. The max-plus system model is adopted to estimate the delay propagation. Monte Carlo simulation is used to evaluate the utilization of regenerative energy and power peaks in random delayed circumstances. The proposed method was adopted to fine-tune the 2019 timetable for a sub-network of the Dutch railway. In the case of on- time scenarios, the optimized timetable increases the regenerative energy usage by almost 290% and decreases the 15-minute power peaks by 8.5%. In the case of delay scenarios, the optimized timetable outperforms the original timetable in terms of using regenerative energy and shaving power peaks.

Design of a High-Efficiency Ka-Band TWT Power Amplifier for Radar Applications

The design of a high-efficiency traveling-wave tube (TWT) based on a nonconventional folded waveguide slow wave structure (FW-SWS) operating over 34–36 GHz for naval and ground Ka-band radars is presented. The ridge-vane-loaded FW structure allows a good compromise between high interaction impedance and wide bandwidth along with a low weight required for aircraft radar applications and a simple planar manufacturing process structure. Small-signal simulations are performed with a custom interaction impedance evaluation program. The CST suite 2021 3-D electromagnetic simulation code is used for the prediction of the dispersion diagram. Starting from a sensitivity analysis of the FW in terms of width, a high electronic efficiency value of 14.6% is obtained with a reduction in the width of 0.1 mm. To further improve electronic efficiency, a negative phase-velocity step tapering technique is applied and a value of 15.4% from 34 to 36 GHz is obtained. Finally, under an optimized beam voltage and a current of 21 kV and 550 mA, respectively, a peak value of the output power of approximately 1.7 kW and an output power of 800 W with a duty cycle of 12% over the frequency band are obtained. Measurement results of the interaction impedance of a ridge-vane-loaded FWG structure composed of a ten-period high-conductivity oxygen-free copper carried out according to the Langerstrom perturbation method confirm the goodness of the simulation results.