Calculation Of Output Power Research Articles

Energy Supply Characteristics of a Combined Solar Cell and Diesel Engine System with a Prediction Algorithm for Solar Power Generation

The production of electricity from the solar cells continues to attract interest as a power source for distributed energy generation. It is important to be able to estimate solar cell power to optimize system energy management. This paper proposes a prediction algorithm based on a neural network (NN) to predict the electricity production from a solar cell. The operation plan for a combined solar cell and diesel engine generator system is examined using the NN prediction algorithm. Two systems are examined in this paper: one with and one without a power storage facility. Comparisons are presented of the results from the two systems with respect to the actual calculations of output power and the predicted electricity production from the solar cell. The exhaust heat from the engine is used to supply the heat demand. A back-up boiler is operated when the engine exhaust heat is insufficient to meet the heat demand. Electricity and heat are supplied to the demand side from the proposed systems, and no external sources are used. When the NN production-of-electricity prediction was introduced, the engine generator operating time was reduced by 12.5% in December and 16.7% for March and September. Moreover, an operation plan for the combined system exhaust heat is proposed, and the heat output characteristics of the back-up boiler are characterized.

Methods and protocols for incremental exercise testing in tetraplegia, using arm-crank ergometry assisted by Functional Electrical Stimulation

Cervical spinal cord injury (SCI) leads to tetraplegia, with paralysis and loss of sensation in the upper and lower limbs. The associated sedentary lifestyle results in an increased risk of cardiovascular disease. To address this, we require the design of exercise modalities aimed specifically at tetraplegia and methods to assess their efficacy. This paper describes methods for arm-crank ergometry (ACE) assisted by Functional Electrical Stimulation (FES) applied to the biceps and triceps. The instrumented ergometer enables work-rate control during exercise, implemented here for incremental exercise testing during FES-ACE. Detailed protocols for the tests are given. Experimental data collected during exercise tests with tetraplegic volunteers are provided to illustrate the feasibility of the proposed approach to testing and data analysis. Incremental tests enabled calculation of peak power output and peak oxygen uptake. We propose that the high-precision exercise testing protocols described here are appropriate to assess the efficacy of the novel exercise modality, FES-ACE, in tetraplegia.

Fatigue-related changes in stance leg mechanics during sidestep cutting maneuvers

Background The increased number of women participating in sports has been paralleled by a greater knee injury rate in women compared to men. Among these injuries, those occurring to the anterior cruciate ligament are commonly observed during sidestep cutting maneuvers. In addition, general fatigue appears to correlate with injuries to the passive structures during a game. The purpose of the study was to examine the fatigue-related changes in lower limb mechanics during a cutting maneuver in female athletes. Methods Twelve college female soccer players were recruited. Sidestep cutting maneuvers were performed prior to, and after a fatiguing exercise (60-min shuttle run). Fatigue state was evaluated by calculating power output from countermovement jumps performed before and after the shuttle run. Three-dimensional stance leg hip, knee and ankle kinematics and kinetics during the cutting task were calculated and reported as initial ground contact angle, ranges of motion and peak moments of the stance phase. Cutting maneuver stance leg mechanics were analyzed through repeated measures two-way ANOVAs ( P < 0.05). Findings Jumping power output decrements suggested fatigue was induced. Sagittal and frontal planes kinematics and kinetics of the cutting task did not change after fatigue. In the transverse plane, the hip, knee and ankle joints were more externally rotated at touchdown, and during stance the knee underwent greater internal rotation. Interpretation Increased knee internal rotation has potentially important implication for increased injury risk when combined with unexpected perturbation faced in a game. Also, the fact that the sub-maximal level of fatigue did not lead to greater dynamic changes suggests a possible threshold of fatigue before function is dramatically affected.

Numerical modeling of a fast-axial-flow CW–CO 2 laser

A four-temperature model has been applied on a fast axial flow, longitudinal discharge CO 2 laser. Using Runge–Kutta method, a set of differential equations of the model is numericaly solved. These equations describe the operation of the laser with certain ratio 1:3:6 of the mixture CO 2:N 2: He and average output power of 550 W. The temporal behaviour of the output power and photon density was obtained. The effects of kinetic temperature, coupled mirror reflectivity, gas flow speed, and cavity loss on the output power were studied. Calculated output power was compared with its measured value taken from experiment and a good agreement was observed.

SLOW-FLYING PIGEONS PUT MORE POWER INTO IT

Bird flight aerodynamics researchers often base their flight models on man-made flying machines. This may work for soaring and gliding birds, but as Jim Usherwood points out, `slow-flapping birds really don't resemble planes'. So Usherwood and his colleagues came up with an innovative approach involving pressure sensors to calculate the aerodynamic power of slow-flapping pigeons(p. 355).`To calculate the aerodynamic power output of a bird's flight muscles you need to know the forces acting on a bird's wing and the speed of the wing'says Usherwood. He explains that there are two non-independent types of force acting when you see a bird flying - those that keep the animal in the air, and those that require muscular work to keep the animal flying. These forces result from pressure differences. `If you know the pressure difference between the top surface and the bottom surface of a bird's wing, you can calculate the force acting on the wing,' says Usherwood. To calculate the forces acting during slow-flapping flight, he needed to measure the pressure at different points on pigeons' wings during flight.Teaming up with Tyson Hedrick, Craig McGowan and Andrew Biewener, Usherwood began adapting pressure sensors so that he could attach them to the birds. The challenge was modifying pressure sensors to stay in place despite the large accelerations of the flapping wings. The team eventually succeeded in pinning pressure sensors through eight feathers on the birds' wings. With the sensors firmly in place, the team used high-speed digital video to record the pigeons'flapping flight as they flew between two perches. The team calculated the birds' aerodynamic power output by combining measurements of the birds' wing speed from the digital videos with simultaneous pressure sensor measurements.The team's novel approach provides a valuable test of the accuracy of direct wing muscle measurements, which until now provided the only method of calculating power output directly. But the team's calculations of the power output of slow-flapping flight are higher than those obtained from direct wing muscle measurements in previous studies. Usherwood emphasizes that each component of his team's power output calculation is reasonable, and slow flight may simply be more energetically expensive and aerodynamically inefficient than previously thought, resulting in higher power outputs than had previously been predicted.Usherwood is enthusiastic about this new approach. `Now that we know that the pressure sensors work, we want to take the set-up outside,' he says;`eventually, we'd like to be able to calculate power output while birds are behaving naturally, such as during migration or foraging.'

Semi-gas kinetics model for performance modeling of flowing chemical oxygen-iodine lasers (COIL)

A semi-gas kinetics (SGK) model for performance analyses of flowing chemical oxygen-iodine laser (COIL) is presented. In this model, the oxygen-iodine reaction gas flow is treated as a continuous medium, and the effect of thermal motions of particles of different laser energy levels on the performances of the COIL is included and the velocity distribution function equations are solved by using the double-parameter perturbational method. For a premixed flow, effects of different chemical reaction systems, different gain saturation models and temperature, pressure, yield of excited oxygen, iodine concentration and frequency-shift on the performances of the COIL are computed, and the calculated output power agrees well with the experimental data. The results indicate that the power extraction of the SGK model considering 21 reactions is close to those when only the reversible pumping reaction is considered, while different gain saturation models and adjustable parameters greatly affect the output power, the optimal threshold gain range, and the length of power extraction.

Effect of inertia on performance and fatigue pattern during repeated cycle sprints in males and females.

The effect of recovery duration on performance and fatigue pattern during short exercises was studied including and excluding the flywheel inertia. Subjects (11 males and 11 females) performed a force-velocity test to determine their optimal force (f (opt)). On the following day, subjects performed randomly 4 series of two 8-s sprints against f (opt), with 15 s (R (15)), 30 s (R (30)), 60 s (R (60)), and 120 s (R (120)) recovery between sprints. The cycle (Monark 824 E, Stockholm, Sweden) was equipped with an optical sensor to calculate the revolution velocity of the pedal. For each sprint, peak power (P (peak)), mechanical work (W) and time to reach P (peak) (t (Ppeak)) were calculated including (I) and excluding (NI) the acceleration of the flywheel. For a given sprint, P (peak) and W were greater and t (Ppeak) was lower in I compared to NI condition (p < 0.05). Differences averaged 13 % for P (peak), 20 % for W, 34 % for t (Ppeak), and remained constant between sprints 1 and 2. In sprint 2, P (peak) and W were significantly reduced compared to sprint 1 only after R (15) and R (30) in I and NI (p < 0.05), and no gender differences occurred. In each sprint, P (peak) and W were higher (p < 0.001) and t (Ppeak) was shorter (p < 0.05) in males than in females, and gender differences were the same including or excluding the flywheel inertia. In conclusion, values excluding inertia underestimated mechanical performance and consequently the total energy supply. However, the pattern of fatigue and gender differences in performance and fatigue remained unchanged whatever the condition (I or NI). This result may have practical implications when the flywheel inertia can not be taken into account in the calculation of mechanical work and power output.

Low light conditions modelling for building integrated photovoltaic (BIPV) systems

The low irradiance efficiency of photovoltaic modules is important to the optimization of BIPV systems. When photovoltaic modules are integrated into a building, architectural design considerations compete with maximizing photovoltaic energy production. As a result, BIPV arrays are often not facing south and are frequently mounted vertically. Under these conditions, a greater portion of the total sunlight striking the array is diffuse or at high angles of incidence. In northern latitudes a significant amount of the total yearly energy is produced at low light levels. A grid-connected array of BIPV modules integrated into the BCIT Technology Centre building in Burnaby, B.C. was used for assessing the accuracy of an energy performance model developed for BIPV systems. The BIPV system uses AC modules and a computerized data acquisition system for monitoring the performance of modules and inverters. The performance model was developed from analysis of the open circuit voltage, maximum power point voltage and maximum power point current of the individual modules comprising the BIPV array. The algorithm for calculating power output of the photovoltaic array is derived from the ideal diode equation using the single diode model of a photovoltaic cell. An empirically derived parameter modifies the equation. Once the parameters for different module technologies are established, it is possible to compare their annual performance in a BIPV system.

Design of a Diode-Pumped Yb:YAG Rod Laser with High Efficiency by Using a Diffusive Optical Cavity

A diode-pumped Yb:YAG rod laser is designed using a fivefold symmetric diffusive optical cavity to improve the pump absorption efficiency of the pump power. By using a ray-tracing method, the optimum design parameters for the doping density, the radius of the diffusive optical cavity, and the radius of the crystal rod are determined by analyzing the absorbed pump power, the distribution profile of the absorbed power, and the threshold absorbed pump power. Based upon these analyses, we show that a highly efficient Yb:YAG rod laser is feasible with the fivefold symmetric diffusive optical cavity. The pump absorption efficiency of 63.6%, which is calculated for the optimal design parameters, corresponds to a 2.4 times improvement in comparison to that obtained by Sumida et al. [Laser Focus World (June, 1999) 63]. By using the absorbed power distribution, we achieved a more realistic quasi-three-level laser output power calculation. In addition, we developed a realistic code, utilizing the absorbed power distribution, for calculating the output power of a quasi-three-level laser. For an incident pump power of 600 W, the laser output power is calculated to be 126 W with optical-to-optical efficiency of 21% and slope efficiency of 42.9%.

High frequency GaN/AlGaN HEMT class-E power amplifier

We report the analysis and simulation of GaN/AlGaN HEMT microwave class-E power amplifiers. The load network of the class-E amplifier is designed by considering exponential decay of the drain current during fall time and finite quality factor of the resonant circuit to incorporate the nonidealities of the active device and passive components. The class-E amplifier has been simulated using Cadence circuit simulator with different HEMT structures. Calculated output power and power conversion efficiency are 93 mW and 72% at 1 GHz that decreases to 69 mW and 68% at 11 GHz, respectively for a 1 μm×150 μ m GaN/Al 0.25Ga 0.75N HEMT. For a 0.12 μm×100 μm GaN/Al 0.20Ga 0.80N HEMT the corresponding quantities are 131 mW, 82%, 87 mW and 77%, respectively.

Design and fabrication of a diode-side-pumped Nd:YAG laser with a diffusive optical cavity for 500-W output power.

A ray-tracing code has been developed, and the design parameters of the laser pump head were analyzed in terms of crystal diameter, doping concentration, and optical cavity diameter. According to the numerical analysis, we fabricated an efficient diode-pumped Nd:YAG laser and experimentally obtained 500-W output power. The output power is close to the numerically calculated output power of approximately 450 W and corresponds to an optical-to-optical conversion efficiency of 46.7% and an optical slope efficiency of 49%.

Assessment of Outputs from Smith-Root Model-5.0 GPP and Model-7.5 GPP Electrofishers

Abstract We evaluated the outputs from eight Smith-Root electrofishers (two factory-rigged model-5.0 GPP boats, four biologist-rigged model-5.0 GPP boats, and two biologist-rigged model-7.5 GPP boats), using an oscilloscope to determine the actual waveforms (voltage as a function of time), current, and power produced for various settings. Differences were found in average power outputs among the six model-5.0 GPP electrofishing boats. In terms of average power output, biologist-rigged electrofishing boats using generators and control boxes purchased from Smith-Root were as or more effective than those rigged by Smith-Root. However, factory-rigged boats generally contained additional safety features that should be considered when purchasing electrofishing equipment. Outputs were similar between the two model-7.5 GPP boats. We were unable, with information obtained solely from the control boxes, to calculate power output produced by the Smith-Root electrofishers. Thus, additional meters (e.g., a voltage met...

A temperature-dependent nonlinear analysis of GaN/AlGaN HEMTs using Volterra series

Gain and intermodulation distortion of an AlGaN/GaN device operating at RF have been analyzed using a general Volterra series representation. The circuit model to represent the GaN FET is obtained from a physics-based analysis. Theoretical current-voltage characteristics are in excellent agreement with the experimental data. For a 1 /spl mu/m/spl times/500 /spl mu/m Al/sub 0.15/Ga/sub 0.85/N/GaN FET, the calculated output power, power-added efficiency, and gain are 25 dBm, 13%, and 10.1 dB, respectively, at 15-dBm input power, and are in excellent agreement with experimental data. The output referred third-order intercept point (OIP/sub 3/) is 39.9 dBm at 350 K and 33 dBm at 650 K. These are in agreement with the simulated results from Cadence, which are 39.34 and 35.7 dBm, respectively. At 3 GHz, third-order intermodulation distortion IM/sub 3/ for 10-dBm output power is -72 dB at 300 K and -56 dB at 600 K. At 300 K, IM/sub 3/ is -66 dB at 5 GHz and -51 dB at 10 GHz. For the same frequencies, IM/sub 3/ increases to -49.3 and -40 dB, respectively, at 600 K.

Total power output generated during dynamic knee extensor exercise at different contraction frequencies

A novel approach has been developed for the quantification of total mechanical power output produced by an isolated, well-defined muscle group during dynamic exercise in humans at different contraction frequencies. The calculation of total power output comprises the external power delivered to the ergometer (i.e., the external power output setting of the ergometer) and the "internal" power generated to overcome inertial and gravitational forces related to movement of the lower limb. Total power output was determined at contraction frequencies of 60 and 100 rpm. At 60 rpm, the internal power was 18+/- 1 W (range: 16-19 W) at external power outputs that ranged between 0 and 50 W. This was less (P<0.05) than the internal power of 33+/-2 W (27-38 W) at 100 rpm at 0-50 W. Moreover, at 100 rpm, internal power was lower (P<0.05) at the higher external power outputs. Pulmonary oxygen uptake was observed to be greater (P<0.05) at 100 than at 60 rpm at comparable total power outputs, suggesting that mechanical efficiency is lower at 100 rpm. Thus a method was developed that allowed accurate determination of the total power output during exercise generated by an isolated muscle group at different contraction frequencies.

Numerical Calculation of Laser Output Power for Various Hermite-Gaussian Modes in a Diode-Pumped Nd:YAG Laser with a Modified Reflective Compound parabolic concentrator

Numerical Calculation of Laser Output Power for Various Hermite-Gaussian Modes in a Diode-Pumped Nd:YAG Laser with a Modified Reflective Compound parabolic concentrator

Annular resonator with a Cassegrain configuration

An advanced annular resonator is studied both theoretically and experimentally. This resonator has a Cassegrain mirror configuration and is designed to extract circular and high-quality beams from annular gain media. We carried out beam propagation in this resonator, calculating the intensity distributions of the laser beam. We also proved the performance experimentally by applying the resonator to a CO2 laser. The operation of the new resonator is demonstrated successfully. The quality of the output beam is in good agreement with theoretical calculations of laser output power of 20 W.

Outdoor performance of amorphous silicon and polycrystalline silicon PV modules

The daily watt-hour efficiency ( η Wh) and daily integrated output power ( P Wh) of the a-Si and poly-Si module have been used to examine the performances of both modules on the basis of two years' data accumulated at outdoor conditions. Results from the analysis of experimental data taken under incident solar energy higher than 3.0 kWh/m 2 per day show that the annual average of η Wh of the a-Si module is about 95% and 92.5% of its efficiency at STC condition at the first and second year, respectively, while the values are nearly unchanged at about 89% for the poly-Si module. During a one year period, the average P Wh of the a-Si and poly-Si module was about 60% and 56%, respectively, of their calculated output power at STC condition, so that the P Wh for each watt-peak ( W p) of the maximum power of a-Si module is about 11% higher than that of the poly-Si module.

A new method for the calculation of constant supra-??VO2peak power outputs

This investigation compared the variance in times to exhaustion among four different methods of supra-VO2peak power output calculation. Ten male subjects cycled to exhaustion at power outputs equivalent to 1) 120% VO2peak, 2) 6 W.kg-1, 3) 100% VO2peak + 10% of the peak anaerobic scope (PAS), and 4) 100% VO2peak + 20% of the mean anaerobic scope (MAS). PAS was defined as the difference between the peak power output (PPO) during a 30-s all-out cycle sprint and the power output at VO2peak MAS was defined as the difference between the mean power output (MPO) during a 30-s all-out cycle sprint and the power output at VO2peak. While the mean times to exhaustion for the four methods were not significantly different, the supra-VO2peak power output calculated as 120% VO2peak resulted in significantly more variance (P = 0.0173) in the times to exhaustion than did the power output equivalent to 20% MAS + 100% VO2peak (SE 16.2 s vs 6.9 s). The variance in time to exhaustion was significantly higher with the power output of 6 W.kg-1 than for the remaining three methods, while the variance in times to exhaustion at a power output of 10% PAS + 100% VO2peak was not significantly different from either 120% VO2peak or 20% MAS + 100% VO2peak. These results indicate that a supra-VO2peak power output that accounts for both aerobic ability and anaerobic work capacity (20% MAS + 100% VO2peak) results in less variance in time to exhaustion than a method which extrapolates the submaximal power output-VO2 relationship to a supramaximal intensity (120% VO2peak).

INVERSE HEART RATE-POWER RELATIONSHIP IN EXPERIENCED, INTERMEDIATE, and NOVICE INDOOR ROCK CLIMBERS 1254

Rock climbing is an activity that has the potential to place both physical and emotional stress on participants. To test the hypothesis that novice rock climbers would be marked by low power output and high heart rates while climbing in a controlled situation, 32 volunteers climbed a 12m indoor rock wall at a self determined pace while wearing standard safety equipment. Based on previous climbing experience, volunteers were categorized as NOVICE (N=17), INTERMEDIATE(N=6) or EXPERIENCED(N=9). Heart rate was recorded during climbing using Polar CIC HR monitor. HRbot was measured at the bottom of the rock wall. HRtop was defined as the value at the top of the rock wall at the end of the vertical climb. Body weight, vertical displacement, and elapsed time were used to calculate power output during climbing. ANOVA and Schette S were used to test for significant (.05) differences. Body weight was not different between groups. There no between group differences in HRbot. HRtop was significantly lower in the experienced climbers(x=138±23) than in either intermediate (143±12) or NOVICE(156±13). Whole body power output was significantly higher in EXPERIENCED climbers (x=183±55 watts) than in NOVICE (x=96±36 watts). There was no difference in calculated power between INTERMEDIATE(176±48 watts) and EXPERIENCED groups. This data suggests that the HR response to rock climbing is not likely to be indicative of aerobic power output as in many recreational activities. The elevation of HRtop in NOVICE and INTERMEDIATE climbers may be the result of increased isometric and isotonic arm contractions as they hold their position on the rock wall in order to decide upon a route. Additionally, there may have been a psychological stress component effecting HR. Borg's 20 point rating of perceived exertion (RPE) administered to all climbers. The NOVICE RPE at the end of the climb was x=12.2±3 while RPE was x=10.3±2.3 and x= 8.7±2.0 in INTERMEDIATE and EXPERIENCED climbers. The degree to which RPE ratings were influenced by physical stress versus fear was not explored in this investigation.

Development of Simulation Program of Electric Power Generated by PV System Using New I-V Curve Construction Method.

In the design, operation and evaluation of a photovoltaic power generation systems (PV systems), it is particularly important to accurately estimate the total amount of annual electric power generated by PV system. The authors applied a new I-V curve construction method developed for the calculation of output power from a photovoltaic array in order to develop a practical “simulation program for the calculation of the amount of electric power generated by PV system.” The following items were clarified by this research.