Greater Peak Power Research Articles

Experimental Investigation on the Performance of the Scroll Expander under Various Driving Cycles

Energy storage is considered a crucial unit in utilizing renewable energy sources, and compressed air energy storage (CAES) provides a cost-effective solution. It offers the benefits of zero pollution, a long lifespan, low maintenance costs, and minimal environmental impact. In order to increase the possibilities of compressed air energy storage for vehicle power, the performance of the expander needs to be studied. First, a CAES unit test bench is established. Then, the volumetric flow rate, rotational speed, torque, and output power are examined. Additionally, the isentropic exhaust temperature, pressure, and gas consumption rate of the scroll expander are analyzed. Finally, analyzing the economic feasibility of the CAES unit entails running the unit under varied driving conditions. Results reveal that the pressure of the input expander is high, which will lead to greater torque, greater peak power, and a greater temperature drop, but the gas in the air tank will also run out quickly. The peak power of the scroll expander does not occur at the maximum volume flow rate, rotation speed, and torque. The basic investment of the CAES unit mainly depends on the peak output power.

Unimodal and bimodal curves of ground reaction force-time profiles identify the drop jump performance

ABSTRACT This study aimed to investigate the kinematics and kinetics differences in ground reaction force (GRF)-time profiles with uni- and bimodal curves (UNC and BIC) during the concentric phase of the drop jump (DJ). Twenty two male Physical Education college student who met UNC (N = 11) or BIC (N = 11) of the GRF-time profile of were recruited. Two force plates and eight infrared optical cameras were synchronised to collect the GRF and motion data during DJ from a 30-cm height. The Shapiro-Wilk test was used to assess the normality of data. The Wilcoxon test was used when data were not normally distributed. Otherwise, Independent t-tests were used to compare differences between the UNC and BIC groups for each dependent variable. The UNC group demonstrated shorter ground contact time, lower jump height, greater leg stiffness, greater peak power during the eccentric phase, less work during the eccentric and concentric phases, and greater hip and knee joint flexion and extension angle displacements (p < 0.05). No significant intergroup differences were found in reactive strength index (p > 0.05). The UNC and BIC of the GRF-time profiles can indicate whether athletes can practice DJ appropriately. UNC can be representative of a better DJ performance with an efficient stretch-shortening cycle function.

Walking in high-heel shoes induces redistribution of joint power and work

ABSTRACT Walking in high-heel shoes (HHS) decreases the push-off power and little research has examined the specific muscle groups that compensate for it. The purpose was to examine the effects of walking in HHS compared to barefoot on lower extremity net joint work and power. Fourteen young women walked in HHS and barefoot at a fixed speed of 1.3 m·s−1. Marker position and ground reaction force data were synchronously measured at 100 and 1000 Hz, respectively. Peak power and joint work variables were computed over the power phases of the gait cycle using an inverse dynamic approach. When walking in HHS was compared to barefoot, participants exerted a diminished push-off characterized by lesser peak power and lesser work by the ankle plantar flexors in late stance (A2 phase; p < 0.001). To compensate for the reduced ankle plantar flexor power, greater peak power was generated and work was performed in early stance by hip extensors (H1 phase; p ≤ 0.001), in mid-stance by knee extensors (K2 phase; p < 0.001) and in late stance and early swing phase by hip flexor muscles (H3 phase; p ≤ 0.001). Walking in HHS induces biomechanical plasticity and causes distal-to-proximal redistribution of net joint power and work during walking.

Quantitative Analysis of Postural Balance in Faller and Nonfaller Patients with Parkinson's Disease.

Postural instability has been identified as a fall risk factor with a significant impact on the quality of life of patients with Parkinson's disease (PD). The aim of this study was to compare the center of pressure (COP) between faller and nonfaller patients with PD during static standing. Thirty-two faller patients and 32 nonfaller patients with PD participated in this study. All patients performed the static balance test on a force plate. COP data were recorded during quiet standing. Mean distance, sway area, mean velocity, mean frequency, and peak power were derived from the COP data. Statistical analysis was performed using independent t-tests to compare faller and nonfaller patients. Fallers presented a greater average distance, wider sway area, faster average speed, and greater peak power than nonfallers (p < 0.05). In contrast, no significant group differences were observed in peak frequency and mean frequency (p > 0.05). Although falls occur during dynamic activities, our study demonstrated that even a safe and simple static postural balance test could significantly differentiate between faller and nonfaller patients. Thus, these results suggest that quantitatively assessed static postural sway variables would be useful for distinguishing prospective fallers among PD patients.

Predictors Of Functional Performance Among Older Adults

Age-associated reductions in muscle strength and power are associated with decrements in functional performance. It is unclear which neuromuscular factors that contribute to strength and power (e.g. muscle mass, contractile speed) and limb fatigability (activity-induced reduction in strength and power) are predicative of functional performance among old adults. PURPOSE: The aim was to determine the contribution of lower limb fatigability and neuromuscular factors to decrements in functional performance tests among older adults. METHODS: Eighty-one adults (39 females, 42 males: 61 - 93 years, 73 ± 7.7 years, body mass index = 26.4 ± 4.1 kg/m2, body fat = 34.7 ± 7.8 %) participated in sessions to assess; 1) Physical function including a 6-minute walk, chair-rise (x5), timed stair-climbing and balance (Berg balance); 2) Dual-energy X-ray absorptiometry to access the body composition; and, 3) fatigability of the knee extensor muscles which involved 80 maximal velocity concentric contractions (1/3 s) with a load of 20% of the maximal voluntary isometric contraction. Voluntary activation and contractile properties of the knee extensors were assessed with transcranial magnetic stimulation and peripheral nerve stimulation before, and after the fatiguing task. Correlation analysis and regression analysis were performed to determine which variables were predictive of physical function. RESULTS: Distance walked over 6 minutes was associated with younger age, greater power, more thigh lean tissue and lower knee extensor fatigability (R2=0.55, P<0.001). Faster chair-rise time (x5) was associated with younger age, less body fat, and lower fatigability (R2=0.44, P<0.001). Both a faster stair-climb (R2=0.3, P<0.001) and a higher Berg balance score (R2=0.43, P<0.001) were associated with younger age and less body fat. CONCLUSIONS: Our findings demonstrate that younger age, greater peak power and lower fatigability of a dynamic fatigue task were strong predictors of lower limb functional performance tasks that are common to daily activities among older adults. Our results also suggest that interventions to offset age-related declines in lean mass and increases in body fat will aid in maintenance of functional performance with advancing age.

Influences of the Stretch-Shortening Cycle and Arm Swing on Vertical Jump Performance in Children and Adolescents.

Gillen, ZM, Shoemaker, ME, McKay, BD, Bohannon, NA, Gibson, SM, and Cramer, JT. Influences of the stretch-shortening cycle and arm swing on vertical jump performance in children and adolescents. J Strength Cond Res 36(5): 1245-1256, 2022-This study compared the influences of the stretch-shortening cycle and arm swing on vertical jump performance during static jumps (SJs), counter-movement jumps (CMJs), and CMJs with arm swing (CMJAs) in young male and female athletes. Twenty-one boys (age = 12.1 ± 1.1 years) and 21 girls (age = 12.1 ± 1.1 years) performed SJs, CMJs, and CMJAs on force plates that sampled at 1 kHz. Measurements included peak force, rate of force development, peak power (PP), eccentric impulse (ECC), concentric impulse (CON), estimated jump height (JH), and changes in PP and JH across vertical jumps. Measurements of growth included age, maturity offset, height, body mass, fat-free mass, and thigh muscle cross-sectional area. Analyses of variance were used to analyze growth measurements across sex, as well as vertical jump outcome measures. Pearson product moment correlation coefficients were used to determine the relationships between changes in PP and JH across vertical jumps and growth measurements. There were differences in PP and JH such that SJ < CMJ < CMJA (p < 0.001), and ECC such that SJ < CMJA < CMJ (p ≤ 0.048). Changes in PP were greater from the SJ to CMJ than CMJ to CMJA (p ≤ 0.001). The change in PP from the SJ to CMJ exhibited moderate-to-high relationships with growth measurements for boys and girls (r = 0.543-0.803). Because young children may not have the skeletal musculature or strength necessary to absorb and reapply large eccentric preloading forces, future studies should consider using the CMJA, rather than the CMJ, to maximize vertical jump performance and minimize ECC. Coaches and practitioners can expect approximately 27-33% greater PP and 15-17% greater estimated JH when an arm swing is included during the CMJ.

Priming exercise increases Wingate cycling peak power output

Purpose: The aim of the present study was to investigate the effect of priming exercise on Wingate performance and fatigue. Methods: Twelve recreationally active young male volunteers participated in the study (age: 25 ± 5 years; weight: 75.0 ± 7.5 kg; height: 177 ± 6 cm; BMI: 24.0 ± 1.7). During a first visit, participants performed a typical test and a supramaximal assessment of on a cycle ergometer, while during the next three visits, the participants performed in a random order a Wingate test (i) with no priming exercise, (ii) after priming exercise followed by a 15-min recovery (Priming15) and (iii) after priming exercise followed by a 30-min recovery (Priming30). Priming exercise lasted 6 min, at work rate corresponding to the gas exchange threshold (GET) plus 70% of the difference between the GET and . Results: The Priming 30 condition exhibited greater peak power output (595 ± 84 W) compared to the control (567 ± 85 W) and the Priming15 condition (569 ± 95 W) (P < .05). Regarding fatigue index, a tendency towards increased resistance to fatigue was observed in the Priming30 condition compared to the control and the Priming15 conditions (P = .072). Pre-Wingate lactate levels were found to be significantly different between the Priming15 (7.18 ± 3.09 mmol/L) and the Priming30 (4.87 ± 2.11 mmol/L) conditions (P < .05). Conclusions: Priming exercise of high intensity followed by a prolonged recovery leads to increased peak power in a subsequent Wingate test. Moreover, our data are consistent with the idea that a priming exercise-induced modest increase in blood lactate concentration at the onset of the following criterion bout is a key factor of performance.

Repeated anaerobic tests predict performance among a group of advanced CrossFit-trained athletes.

High-intensity functional training (HIFT) (i.e., CrossFit (CF) training) uses a combination of movements and self-selected time periods of work and rest. However, little is known about the physiological responses to an acute bout of HIFT exercise or about the physical parameters that distinguish performance. The purpose of this study was to examine the physiological responses in advanced CF athletes to consecutive Wingate trials with short, active recovery periods. Twenty-nine advanced-level CF-trained athletes volunteered for this study. The participants were required to complete 4 consecutive Wingate anaerobic tests (WAnTs) and a 15-min CF-style workout. Across the 4 WAnT trials, significant (p < 0.001) changes were observed in oxygen consumption, respiratory exchange ratio, and heart rate. Significant (p ≤ 0.001) differences among WAnT trials were observed in all anaerobic performance measures. Compared with all other trials, greater peak power (p < 0.04), relative peak power (p < 0.02), average power (p < 0.001), relative average power (p < 0.001), and total work (p < 0.001), together with a lower fatigue index (p < 0.01), were observed during WAnT 1. Overall, the 4 consecutive WAnT trials resulted in a significant (F = 177.0, p < 0.001) increase in blood lactate response. Stepwise regression revealed that the ability to predict total repetitions completed during the 15-min trial to complete as many repetitions as possible improved as the participants progressed from the first to the third WAnT trial. Our data suggest that, combined with the ability to better maintain performance across high-intensity exercise bouts, the ability to quickly recover between bouts is the most important factor in CF performance.

Motor behavior characteristics in various phases of bipolar disorder revealed through biomechanical analysis: Quantitative measures of activity and energy variables during gait and sit-to-walk

Abnormal motor behaviors influenced by high or low energy states are key signs and symptoms for mania/hypomania or depression, respectively. Clinical evaluation is currently based on qualitative, subjective self-reports. We aimed to objectively quantify activity and energy variables during gait and sit-to-walk in bipolar disorder. Gait and sit-to-walk were analyzed in 31 individuals with bipolar disorder (five hypomanic, 14 euthymic and 12 depressed) and 14 healthy controls using a motion capture system and two force platforms. The 9-item Patient Health Questionnaire and Altman Self Rating Mania Scale were administered to evaluate mood symptoms. During gait and sit-to-walk, the hypomanic group had 20–30% greater movement speed and produced 10–60% greater peak force, and 40–140% greater peak power in the knee or ankle compared to the euthymic, depressed and healthy groups. Biomechanical measures of activity and energy correlated with clinically defined hypomania. Our findings suggest that movement speed and force production could serve as objective activity and energy markers for hypomanic symptoms in individuals with bipolar disorder, but this study was based on a relatively small sample size, and the laboratory-based assessments are not directly transferable to a clinical setting.

The Effect of Age on Technique Variability and Outcome Variability during a Leg Press.

The aim of this study was to determine the effect of aging on power generation and joint coordination during a leg press, in order to increase understanding of how functional movements are affected during the aging process. 44 older and 24 younger adults performed eight sub-maximal power repetitions on a seated leg press dynamometer. Peak power and velocity (at 40% maximum resistance) were measured along with the coordination (coupling angle) of the lower limb joints using the vector coding technique. The younger adults produced significantly greater peak power than the older adults (mean ± SD; 762 W ± 245 vs 361 W ± 162, p < 0.01) and at higher peak velocities (mean ± SD; 1.37 m/s ± 0.05 vs 1.00 m/s ± 0.06, p < 0.01). The older adults produced less consistent values of peak power than younger adults, evidenced by a higher coefficient of variation (mean ± SD; 7.6% ± 5.2 vs 5.0% ± 3.0, p < 0.01), however, there was significantly less variability in the coupling angles displayed by the older adults compared to the younger adults (mean ± SD; 2.0° ± 1.1 vs 3.5° ± 2.7, p < 0.01 (ankle-knee); 1.7° ± 0.6 vs 4.1° ± 3.0, p < 0.01 (knee-hip)). The results of this study demonstrate that older adults display higher outcome variability but lower variability in technique (coordination). The more rigid movement strategies displayed by the older adults potentially reflects an increased risk of overuse injury due to repetitive demands on the same structures, or the reduced ability to respond to unexpected situations due to a lack of flexibility in joint control.

Double nanosecond pulses generation in ytterbium fiber laser.

Double pulse generation mode for nanosecond ytterbium fiber laser was developed. Two sequential 60-200 ns laser pulses with variable delay between them were generated by acousto-optic modulator opening with continuous diode pumping. A custom radio frequency generator was developed to produce two sequential "opening" radio pulses with a delay of 0.2-1 μs. It was demonstrated that double pulse generation did not decrease the average laser power while providing the control over the laser pulse power profile. Surprisingly, a greater peak power in the double pulse mode was observed for the second laser pulse. Laser crater studies and plasma emission measurements revealed an improved efficiency of laser ablation in the double pulse mode.

Physiological and performance characteristics of road, mountain bike and BMX cyclists

The purpose of this research was to quantify several physiological and power output characteristics of high-performance road, cross-country mountain bike (XCMB), downhill mountain bike (DHMB) and bicycle motocross (BMX) cyclists. Twenty-four high-performance cyclists (27 ± 7 yr; 182 ± 6 cm; 79.3 ± 9.7 kg; ∑7SF 69 ± 27 mm; 61.4 ± 9.9 mL·kg -1 ·min -1 ) completed both an incremental ramp test and a power profile assessment (PPA) across two separate testing sessions. The PPA consisted of maximal efforts lasting 5 s, 15 s, 30 s, 60 s, 240 s, and 600 s. The ramp test provided measures of VO 2MAX , maximal aerobic power (MAP) and individual VO 2 -power regression equations, whilst the PPA determined metabolic costs, anaerobic capacity and power output across each effort. The data demonstrated that road and XCMB cyclists possessed significantly (p<0.05) higher VO 2MAX (65.3-69.6 vs. 52.4-55.3 mL . kg -1. min -1 ) and anaerobic capacities (1.7-1.8 vs. 0.9-1.3 L) than the DHMB and BMX cyclists. Further, the same cohorts produced significantly (p ≤ 0.05) greater MAP (5.8-6.3 vs 4.4-4.7 W . kg -1 ), as well as relative mean power output across efforts lasting ≥15 s. The BMX and DHMB cyclists demonstrated greater peak power outputs (~200 W) across the shorter efforts of the power profile. The data demonstrate that the road and XCMB cyclists possessed higher aerobic physiological capacities and power outputs than the DHMB and BMX cyclists. The latter disciplines possessed greater explosive power outputs. Together, these findings reflect the specificity of selected traits that are possessed within each cycling discipline.

The Effect of Peak Power and Pulse Duration for Dissimilar Welding of Brass to Stainless Steel

A pulsed Nd:YAG laser was used to weld overlap joint between H62 brass and 316L stainless steel in thermal conductivity welding mode. Effects of peak power and pulse duration were investigated under the condition of constant pulse energy. Optical microscopy (OM), scanning electron microscope, and X-ray diffraction were used to analyze the microstructure, defects, and intermetallic phases in the interface, respectively. Microhardness test and tensile test were carried out to identify the mechanical property on the welded joints. The results showed that the microstructure, penetration-to-width ratio (ϕ), and mechanical properties were affected by the combined effects of peak power and pulse duration when the pulse energy was constant. When the magnitude of the peak power equals to 1846 W, both of penetration-to-width ratio and microhardness in the welded joints stayed to a minimum value. But if the magnitude of the peak power is less than 1846 W, the welded joint has the fewer defects, superior microstructure, and mechanical properties while comparing with the greater peak power.

Children with heavy prenatal alcohol exposure have different frequency domain signal characteristics when producing isometric force

To extend our current understanding of the teratogenic effects of prenatal alcohol exposure on the control of isometric force, the present study investigated the signal characteristics of power spectral density functions resulting from sustained control of isometric force by children with and without heavy prenatal exposure to alcohol. It was predicted that the functions associated with the force signals would be fundamentally different for the two groups. Twenty-five children aged between 7 and 17years with heavy prenatal alcohol exposure and 21 non-alcohol exposed control children attempted to duplicate a visually represented target force by pressing on a load cell. The level of target force (5 and 20% of maximum voluntary force) and the time interval between visual feedback (20ms, 320ms and 740ms) were manipulated. A multivariate spectral estimation method with sinusoidal windows was applied to individual isometric force–time signals. Analysis of the resulting power spectral density functions revealed that the alcohol-exposed children had a lower mean frequency, less spectral variability, greater peak power and a lower frequency at which peak power occurred. Furthermore, mean frequency and spectral variability produced by the alcohol-exposed group remained constant across target load and visual feedback interval, suggesting that these children were limited to making long-time scale corrections to the force signal. In contrast, the control group produced decreased mean frequency and spectral variability as target force and the interval between visual feedback increased, indicating that when feedback was frequently presented these children used the information to make short-time scale adjustments to the ongoing force signal. Knowledge of these differences could facilitate the design of motor rehabilitation exercises that specifically target isometric force control deficits in alcohol-exposed children.

Effect of Load Positioning on the Kinematics and Kinetics of Weighted Vertical Jumps

One of the most popular exercises for developing lower-body muscular power is the weighted vertical jump. The present study sought to examine the effect of altering the position of the external load on the kinematics and kinetics of the movement. Twenty-nine resistance-trained rugby union athletes performed maximal effort jumps with 0, 20, 40, and 60% of their squat 1 repetition maximum (1RM) with the load positioned (a) on the posterior aspect of the shoulder using a straight barbell and (b) at arms' length using a hexagonal barbell. Kinematic and kinetic variables were calculated through integration of the vertical ground reaction force data using a forward dynamics approach. Performance of the hexagonal barbell jump resulted in significantly (p < 0.05) greater values for jump height, peak force, peak power, and peak rate of force development compared with the straight barbell jump. Significantly (p < 0.05) greater peak power was produced during the unloaded jump compared with all trials where the external load was positioned on the shoulder. In contrast, significantly (p < 0.05) greater peak power was produced when using the hexagonal barbell combined with a load of 20% 1RM compared with all other conditions investigated. The results suggest that weighted vertical jumps should be performed with the external load positioned at arms' length rather than on the shoulder when attempting to improve lower-body muscular performance.

Optical pulse compression using the combination of phase modulation and high-order dispersion compensation

Optical pulse compression using high-order dispersion compensation is proposed and theoretically analyzed. Firstly, the required dispersion profile for the high-order dispersion compensation is derived, according to the linear chirp and the nonlinear chirp of a phase-modulated continuous-wave (CW) laser source. With the use of the high-order dispersion compensation, such as the combination compensation of the second order dispersion (SOD) and the fourth order dispersion (FOD), an efficient pulse compression having a less time-bandwidth product and a greater peak power is realized. A sampled fiber Bragg grating (FBG) with both the SOD and the FOD is then designed using the equivalent chirp and the reconstruction algorithm. Finally, in the numerical simulation an optical pulse with a time-bandwidth product of 0.79 is generated via high-order dispersion compensation that is performed by using the sampled FBG.

Assessment of gender differences in maximal anaerobic power by ratio scaling and allometric scaling

The purpose of this study was to determine gender differences in maximal anaerobic power by using both ratio scaling and allometric scaling. 27 males and 26 females voluntarily participated in this study. Wingate test was used to determine both peak power and mean power. Body weight, lean body mass and thigh muscle cross sectional area were determined anthropometrically. Males had significantly greater peak power and mean power in absolute terms, ratio-scaled and allometrically scaled to body weight, lean body mass and thigh muscle cross sectional area ( p< 0.01) compared to females. The relationships between ratio-scaled anaerobic power indices and relevant body size descriptors were significantly different from zero ( p< 0.05). Ratio scaling of anaerobic power indices did not create a dimensionless index as the relationships between ratio-scaled anaerobic power indices and relevant body size descriptors are different from zero. On the other hand, relationships between allometrically scaled anaerobic power indices and relevant body size descriptors approached to zero indicating more dimensionless index compared to ratio scaling. Therefore, allometric analysis should be considered as a method to account for the influence of body size in intergroup and gender comparisons of anaerobic power. Furthermore, we have found significant gender differences in allometrically normalized anaerobic power indicating that other factors in addition to body dimensions accounts for the gender differences in anaerobic power. This result suggests that no method is perfect in accounting for gender differences in anaerobic power and thus physical performance studies of males and females should be conducted seperately.

Brief High-Intensity Exercise and Resistive Force Selection in Overweight and Obese Subjects: Body Mass or Body Composition?

The purpose of this study was to compare the maximal exercise performance of overweight and obese subjects during friction braked cycle ergometry of 10 s duration when resistive forces reflected total-body mass (TBM) or fat-free mass (FFM). Subjects were assigned at random to either protocol. Eleven healthy male university students (age 22.3 ± 2 yrs, body fat 27.1 ± 2%) participated in the study. Differences (P < 0.01) in peak power output (PPO) were found between TBM and FFM (1029 ± 98 W TBM vs. 1397 ± 146 W FFM). The findings of this study suggest that greater peak power outputs are obtainable when resistive forces reflect FFM as opposed to TBM. The results have implications that relate to the pathology of disease, related clinical examinations, and exercise prescription.

Peak Power, Ground Reaction Forces, and Velocity During the Squat Exercise Performed at Different Loads

This study examined the changes in peak power, ground reaction force and velocity with different loads during the performance of the parallel squat movement. Twelve experienced male lifters (26.83 +/- 4.67 years of age) performed the standard parallel squat, using loads equal to 20, 30, 40, 50, 60, 70, 80, and 90% of 1 repetition maximum (1RM). Each subject performed all parallel squats with as much explosiveness as possible using his own technique. Peak power (PP), peak ground reaction force (PGRF), peak barbell velocity (PV), force at the time of PP (FPP), and velocity at the time of PP (VPP) were determined from force, velocity, and power curves calculated using barbell velocity and ground reaction force data. No significant differences were detected among loads for PP; however, the greatest PP values were associated with loads of 40 and 50% of 1RM. Higher loads produced greater PGRF and FPP values than lower loads (p < 0.05) in all cases except between loads equal to 60-50, 50-40, and 40-30% of 1RM for PGRF, and between loads equal to 70-60 and 60-50% of 1RM for FPP. Higher loads produced lower PV and VPP values than lower loads (p < 0.05) in all cases except between the 20-30, 70-80, and 80-90% of 1RM conditions. These results may be helpful in determining loads when prescribing need-specific training protocols targeting different areas of the load-velocity continuum.

Power coordination in a fuel cell–battery hybrid power source using commercial power controller circuits

Hybrid power systems combine the superb energy density of a fuel cell power source with the outstanding power density of modem batteries. A hybrid power source with an integral power distribution and charge management system was designed and built using standard miniature power regulator integrated circuits with appropriate modifications to implement the necessary controls. The resulting converter not only allows the interconnection of fuel cell systems and batteries having dissimilar operating voltages, but it also imposes a power sharing strategy that elicits peak performance from each part of the device. The resulting hybrid power source can supply 70% greater peak power, with only a 6% increase in weight, and no increase in volume, compared to the as-packaged fuel cell power source on which the hybrid source was based.