Power Output Increment Research Articles

An open-loop and closed loop based passive thermal management techniques applicable to photovoltaic systems

Photovoltaic (PV) technology adoption in recent years has experienced significant growth due to its inherent advantages over alternative technologies. Nevertheless, there is a concern regarding performance deterioration due to high operating temperatures. Various thermal management methods have been studied to address this issue, each having its own advantages and disadvantages. Hence, a comprehensive review aimed at developing effective passive cooling techniques was undertaken and two techniques were finalized for outdoor testing viz. natural circulation loop based cooling (PV-NCL) and evaporative cooling (PV-EVP). Though the former version could drop module temperature by 7.4 °C–13.9 °C (Power output increment in the range of 3.5 %–6.7 %), this improvement was not sustained throughout the day due to factors such as flow resistance within the loop and a lack of convective cooling in the vicinity of the cooler. Subsequent experiments confirmed that loop resistance played a dominant role in this phenomenon. Additionally, concerns about water circulation in PV-NCL were resolved through a comparison with water duct-integrated PV. On the other hand, the innovative gravity-assisted water flow for evaporation method (PV-EVP) yielded more promising results, with a power output enhancement ranging from 3.7 % to 11.5 %. However, considering the in-field operational issues, PV-NCL with a modified design will likely be the best technique.

Performance and emission evaluation of CI engine fueled with ethanol diesel emulsion using NiZnFe2O4 nanoparticle additive

Diesel engines are widely used due to their higher thermal efficiency and lower Hydrocarbon (HC) emissions. The price fluctuation of petroleum fuel; the none-renewability and different hazardous emissions from petro-diesel, researchers are searching for a suitable renewable energy source for diesel engine. Ethanol is one of the promising alternative fuels that could be used to power diesel engine. Some of the techniques so far tried are ethanol fumigation, dual injection and blending. The former techniques need different engine modification to enable the additional systems to work on the existing engines. Blending is the best technique to substitute the existing diesel fuel as long as we prepare it as per the current diesel fuel minimum requirement. For this specific case micro emulsion of ethanol in diesel fuel with emulsifier is prepared by using magnetic stirrer and bath type ultrasonicator. Nickel Zinc Iron Oxide (NiZnFe2O4) nanoparticle is added in one of the selected emulsion which is having 10% ethanol in three different dose as additive to see the effect on the performance and emission variation of the emulsion compared with diesel fuel. The performance of the prepared sample fuels are tested on a test rig with single cylinder diesel engine. The emission is measured by using exhaust gas analyzer and smoke opacity meter. The specific fuel consumption, brake torque and brake power of E5 (95% diesel and 5% ethanol), E10 (90% diesel and 10% ethanol) and E15 (85% diesel and 15% ethanol) are evaluated and the result showed 27, 34 and 37% increment in fuel consumption; 15, 5 and 15% reduction in brake torque and the power reduction is 19, 7 and 12% respectively. E10 is selected for further test with addition of the nanoparticle with 25, 50 and 100ppm named as E103N25 (E10 with 25ppm NiZnFe2O4 nanoparticle), E103N50 (E10 with 50ppm NiZnFe2O4 nanoparticle) and E102N100 (E10 with 100 ppm NiZnFe2O4 nanoparticle). The result showed fuel consumption reduction by 16, 27 and 27% torque output increment of 1, 2 and 2% and power output increment of 5, 7 and 7% respectively compared with E10. The emission result revealed that the HC emission reduced by 50, 58 and 71% for E103N25, E103N50 and E103N100 fuel samples respectively, Carbon monoxide (CO) emission reduced by 67, 80 and 81% for E103N25, E103N50 and E103N100 fuel samples respectively. The reduction in smoke emission is reduced by 60, 69 and 61% for E103N25, E103N50 and E103N100 fuel samples respectively. Nitrogen oxide (NOX) and Carbon dioxide (CO2) emissions increased with the amount of nanoparticle added in to the fuel.

A novel degree-hour method for rational design loading

Cooling degree-hours (CDH) received the broadest application in evaluation of the ambient air cooling efficiency in power engineering (engine intake air cooling systems) and air conditioning. The current CDH numbers are defined as a drop in air temperature multiplied by associated time duration of performance and their summarized annual number is used to estimate the annual effect achieved due to sucked air cooling in power plants based on combustion engines (fuel saving, power output increment) and in air conditioning (refrigeration energy generation according to needs). A majority of approaches to designing ambient air cooling systems is proceeding from the cooling capacity of the chillers selected to provide a maximum current or annual CDH number with corresponding maximum current or annual effect (additional energy produced or fuel consumption reduction) in site climate location. But such approaches lead to inevitable oversizing the chillers and cooling systems in the whole. The analysis of intake air cooling efficiency in site varying climatic conditions, accompanied by quite a simple numerical simulation, enabled to reveal the potential of its enhancement and evaluate numerically the results of each step of designing in logical sequence. The new approaches to cooling system rational designing were introduced, that enables to synthesize and substantiate innovative principal decisions to exclude unproductive waste of installed (design) cooling capacity in actual operation. The innovative findings of methodological approaches include the use of the rate of annual CDH number increment as an indicator for selecting the optimum and rational values of design cooling capacity. The optimum cooling capacity corresponds to maximum rate of summarized annual CDH increment and maximum level of thermal loading accordingly, which provides minimum sizes of the chiller. In reality, it is a minimum permissible value of cooling capacity of the chiller installed and the overall ambient air cooling system. The rational cooling capacity, that enables to achieve practically maximum value of annual CDH and avoid chiller oversizing, is determined as the second, local, maximum of the rate in the summarized annual CDH over the range above the first one, global, maximum. A rational design cooling capacity determined by applying the novel methodology allows to decrease the ambient air cooling system sizes by 15 to 20% compared with traditional designing issuing from the peaked thermal load during a year. With this practically a maximum annual effect in fuel saving (energy generation or others) can be achieved too.

Voltage Optimization Control Strategy for Islanded Microgrid Source-Grid-Load Active-Reactive Power Coordination Based on Collaborative Di-MPC

To cope with the volatility and randomness of wind power, photovoltaic (PV) power, and load demands in the islanded microgrid, and also to ensure the safety and economic operation of the islanded microgrid system. A collaborative Distributed model predictive control (Di-MPC) based voltage optimization control strategy is proposed, which considers the strong coupling characteristic of active and reactive power due to the impedance ratio of islanded microgrid, and the requirements of real-time and robustness in the optimization as well. By coordinating the controllable devices in the source-grid-load side of the islanded microgrid, the proposed strategy aims to make full use of the voltage regulation capability of each controllable device. Firstly, by considering the different operating characteristics of the controllable devices, a multi-time scale distributed voltage optimal control model is established. It divides the optimal control process into long-time scale and short-time scale and optimizes for respective objective functions and control variables in different time scales. Secondly, a collaborative Di-MPC-based voltage optimal control strategy is proposed. With the proposed collaboration mechanism, the power output increments of the distributed generators (DGs) are solved in the short-time scale, and the errors in the long-time scale control are also fixed. Finally, the simulation results show that compared with a traditional optimal control method and a centralized model predictive control (CMPC) method, the proposed voltage optimization control strategy can effectively reduce the voltage deviation and fluctuation at each node while ensuring the economic operation of the islanded microgrid system.

A new potential polymeric cladding material for polycarbonate fibre optic core for high temperature use

The selection of a suitable cladding material for a fibre optic is crucial, and the application of polymeric material in high temperature conditions is garnering much attention from many researchers. However, polymer suffers from a weak thermal resistance, limiting its use in high temperature conditions. Therefore, this study aims to develop a new potential cladding material that has a good balance between optical and thermal properties. Two sets of cladding materials are proposed, namely the blend of polycarbonate/polymethyl methacrylate (PC/PMMA) and polymethylpentene (PMP). The cladding materials were dissolved in different solvents, followed by the casting on a glass plate to form a flat sheet cladding layer. PC/PMMA blend showed a miscible blending with a single Tg value and physical blending. Both PC/PMMA blend and PMP claddings demonstrated more than 90% of luminous transparency. The materials also showed high thermal stability with the onset degradation temperature of ∼ 300 °C. The optimum ratio for PC/PMMA was 80/20. Next, the cladding layer was fabricated by coating the core in 80/20 PC/PMMA and PMP. The scanning electron microscopy (SEM) image reveals that core–clad ratio for the PC fibre is 1.02 for both materials. The maximum tensile strength for the PC with PMP cladding was higher than that of the PC with PC/PMMA cladding. PMP-clad fibre has higher power output, which was a 60% increment from bare PC fibre output compared to PC/PMMA-clad fibre, with only 28.8% power output increment. Though both materials have huge potential to be used as the cladding for PC core, PMP cladding showed superior performance compared to PC/PMMA cladding.

Research on influence of steam extraction parameters and operation load on operational flexibility of coal-fired power plant

The operational flexibility of coal-fired power plant is very important for the integration of large-scale renewable energy to the grid. In order to increase the operational flexibility of coal-fired power plant, a 600 MW subcritical coal-fired power plant was selected as research example to analyze the influence of steam extraction parameters and operation load by simulation. A novel main steam extraction system was proposed to adjust the power output under the low load period. The sensible and latent heat of the extracted steam was stored in molten salts and phase change materials, respectively, during the load reduction process. While the stored heat was reused again to heat the feed water and condensate water during the load raising process. The 50% rated load (300.03 MW) of the unit was used as the research benchmark to further adjust the load. The results show that the proposed steam extraction system can improve the operational flexibility of coal-fired power plant. The power output can be reduced to 204.51 MW from 300.03 MW when the main steam extraction mass flow rate is 250 t/h during the load reduction process. The sensible heat storage power factor and the operation load of the unit can affect the power output increment of coal-fired power plant during the load raising process. Under the condition of the maximal sensible heat storage power factor is 0.2462, the power output can be increased to 325.47 MW from 300.03 MW when the bypassed feed water mass flow rate of 251 t/h was heated by the stored heat during the load raising process. Using such operation model, the coal-fired power plant can achieve the maximum deep peak shaving time of 8.4 h/d, and its equivalent thermal efficiency is increased by 2.28%. With the same stored thermal energy to heat the bypassed feed water of 308.65 t/h, the power output can be increased to 394.2 MW from 360.07 MW (60% rated load) at the same sensible heat storage power factor of 0.2462 during the load raising process, and the coal-fired power plant can achieve the maximum deep peak shaving time of 9.86 h/d with its equivalent thermal efficiency increase of 2.55%. The results show that the proposed steam extraction method can make the unit operate in the lowest stable load and provide a wider renewable energy access space below the minimum stable load. The research provides a theoretical guidance for the flexibility design of coal-fired power plant, especially suitable for the large-scale renewable energy access to the grid in China.

Advances of Solar PV System Output Improvement through Cooling Technologies in Malaysia

Solar photovoltaic (PV) panel is the most widely used renewable energy technology in Malaysia due to constant irradiation throughout the year as the country is located near the equator. According to the current state of the Malaysian weather, the ambient temperature is around 25°C and can go up to 30°C. The electrical efficiency of a PV panel is sensitive towards temperature where it is known that the power and efficiency decrease at the rate of ±0.5%/°C and ±0.05%/°C respectively as the ambient temperature increases [1]. This paper discusses the cooling of solar PV technologies, the methodologies of the cooling system and its effectiveness. Generally, the effectiveness of the studies conducted were derived from the solar PV panel temperature reduction and solar PV electricity power output increment. This paper elaborates the trend of methodologies for cooling of solar PV in Malaysian climate. The methodologies that were used by the researchers vary according to the specific objectives which can be categorized as active cooling and/or passive cooling. The gaps of the studies were also identified alongside with the possible solutions to mitigate the problems.

Boxing Training Effects On Cardiorespiratory Fitness In Individuals With Prehypertension

PURPOSE: Boxing training is a type of exercise that involves high cardiovascular demands in an enjoyable environment. Previously, boxing training has shown to have excellent cardiovascular outcomes in obese population, however, research regarding the effects of boxing training on cardiovascular health in individuals with high blood pressure is scarce. The purpose of this study was to determine the effects of a boxing training intervention on maximum oxygen uptake (VO2max), power output, and lactate and ventilatory thresholds in individuals suffering from prehypertension. METHODS: A total of 14 subjects with prehypertensive were randomly assigned to a boxing intervention group or a control group. The intervention had a duration of 6 weeks, meeting 3 sessions weekly. Each boxing session consisted on 10 rounds of 3 minutes and 1 minute rest in between. From those 10 rounds, 3 were set at 95%VO2max and 7 at 60% VO2max. Before and at the end of the intervention, all subjects completed a graded maximal exercise test on an arm-crank ergometer in which VO₂max, power output, and lactate and ventilatory thresholds were obtain. RESULTS: At the end of the intervention, there were significant improvements on power output (p=0.002), ventilatory threshold (p=0.002), and lactate threshold (p=0.001) in the boxing group compared to the control group. Additionally, there was a significant reduction on VO2max in the control group (p=0.04). CONCLUSION: Individuals with prehypertension who underwent 6 weeks of boxing training improve the peripheral component of their cardiovascular fitness based on a significant enhancement in their lactate thresholds and ventilatory thresholds, which in turn produces power output increments. Boxing training may be a suitable exercise alternative to be prescribed in high blood pressure population.

Thermodynamic analysis of a novel transcritical-subcritical parallel organic Rankine cycle system for engine waste heat recovery

In this study, a novel transcritical-subcritical parallel organic Rankine cycle system is proposed to recover the engine exhaust gas and coolant waste heat. Firstly, the proposed system is compared with the dual-loop organic Rankine cycle and parallel organic Rankine cycle systems. According to the results, the proposed system shows more net power output, higher thermal and exergy efficiency, and lower heat transfer requirement. Then the thermodynamic analysis including energy and exergy analysis are carried out, and the effects of design parameters including high-pressure turbine inlet temperature and pressure, low-pressure evaporation temperature on the performance of proposed system based on R601a are investigated. The results indicate that for a given high-pressure turbine inlet temperature, the net power output of system firstly increases and then decreases as high-pressure turbine inlet pressure increases and reaches to the maximum at turbine inlet temperature and pressure of 520 K and 8 MPa, and the net power output also shows a trend of firstly increasing and then decreasing with low-pressure evaporation temperature and reaches to the maximum at 330 K. Furthermore, five low global warming potential fluids are selected as working fluids of proposed system, and the results demonstrate that the R1233zd is the best candidate working fluid for proposed system. The maximum net power output of proposed system based on R1233zd reaches to 119.72 kW at the turbine inlet temperature and pressure of 530 K and 10 MPa, low-pressure evaporation temperature of 330 K, which achieves net power output increment of 12.02% for the engine system. Finally, an exergy destruction analysis demonstrates that the heat transfer processes have less exergy destruction for proposed system based on R1233zd compared with other working fluids.

Influences of Hybrid Cooling Mechanism through PV System under Solar Simulator Testing

An increasing efficiency of the solar system can be improved by using hybrid cooling mechanism. This paper presents the impact of hybrid cooling mechanism on PV panel under indoor testing with varying solar intensity. Thus, the fabrication of a solar simulator for indoor testing reacts as the space solar radiation is described. The performance of PV panel which attached to a hybrid cooling mechanism compared with PV panel without cooling mechanism under variation of average solar radiation. Experimental tests were carried out for various average solar radiations by varying the number of lamps and/or the lamp-to-area distance. Without altering the spectral distribution, the characteristic of current-voltage of PV panel was analysed under average solar radiation which varied from 202 W/m<sup>2</sup> to 1003 W/m<sup>2</sup>. As the result, the PV panel with hybrid cooling system explored to generate more power output with decreasing in PV panel temperature. About 15.79 % increment of power output generated by PV panel with cooling at maximum average solar radiation. Furthermore, the PV panel temperature also can be decreased about 10.28 % respectively. The combination of DC fan and water pump as cooling mechanism plays an important role in generating efficient power output from PV panel.

Parametric optimization of steam cycle in PWR nuclear power plant using improved genetic-simplex algorithm

A parametric optimization framework for the steam cycle of a typical pressurized water reactor (PWR) nuclear power plants (NPP) (i.e. Daya Bay nuclear plant) is proposed. The approach determines the optimal operation parameters of the steam cycle to maximize the power output with primary loop remaining unchanged. Thermodynamic model of the steam cycle system has been established to determine the power output under different operating conditions, and the availability and accuracy of the model are investigated. In addition, an improved genetic-simplex algorithm (IGSA) is put forward by using modified search strategies and integrating genetic algorithm (GA) with simplex algorithm (SA). Performance comparison between the improved algorithm and the original ones is performed by solving the optimization test problems. The improved algorithm enables the handling of nonlinear constrained optimization problem because of dramatically enhanced search capability. Based on the model, the parametric optimization for the steam cycle of Daya Bay PWR nuclear plant is carried out using the IGSA, GA and SA, respectively. In the optimized schemes it has been found that the IGSA can yield increase in power output as much as 23.8MW by an average of 236 iterations over current practice, and the corresponding thermal efficiency increases from 33.87% to 34.69%. In comparison, even more iterations have been executed, the maximum power output increments gained by the GA and SA are 21.4MW and 18.7MW, respectively. The results show that the new algorithm IGSA is superior to original ones. It also demonstrates that the proposed approach can effectively increase the efficiency of the PWR nuclear power plant without burning any additional fuel or replacing the devices of the system.

Effects of the ORC Operating Conditions on the Engine Performance for an Engine-ORC Combined System

Abstract Exhaust waste heat recovery by Organic Rankine cycle (ORC) systems has been proven as an effective way to improve thermal efficiency of engines. The performance of a diesel engine with an ORC system was evaluated in this paper. Both of the engine and the ORC system model were built in GT-SUITE respectively, and the two models were integrated in Simulink environment. The effects of operating conditions of the ORC system on performance of the engine in the combined system were discussed. The performance of the combined system with different inlet temperature of cooling water was also evaluated. The simulation results show that the engine backpressure increases with the decrease of the pump speed and the expander speed. The maximum engine power output increment at the engine speed of 1500 r/min and 2100 r/min is 5.47 kW and 7.07 kW respectively. The backpressure increment of the engine with ORC system increases with the increasing of cooling water inlet temperature.

Performance evaluation of a diesel engine integrated with ORC system

Waste heat recovery from exhaust gas with organic Rankine cycle (ORC) systems is a promising method to improve the overall thermal efficiency of diesel engines. The performance of a diesel engine integrated with an ORC system is evaluated in this paper. Simulation models of the diesel engine and the ORC system are developed in GT-suite separately, and a combined system model is developed in Simulink environment. The engine simulation results are validated experimentally. The steady performance evaluation of the engine with ORC at different engine conditions is presented, and the acceleration performance of the diesel engine with and without ORC is evaluated. The performance of the engine during the ORC expander start-stop process is also discussed. The steady performance simulation results indicate that, the net power output increment, the brake specific fuel consumption (BSFC) reduction and the thermal efficiency improvement of the engine with ORC system can be up to 4.13kW, 3.61g/(kWh) and 0.66%, respectively. The transient performance simulation results show that the ORC system has minimal effects on the acceleration performance of the engine.

Simultaneous optimization and integration of gas turbine and air separation unit in IGCC plant

In Integrated Gasification Combined Cycle (IGCC) plant, Gas Turbine (GT) and Air Separation Unit (ASU) have great influences on the thermal efficiency, especially their interaction. Therefore, it is necessary to discuss them as a whole. The obstacle to achieve this is the complexity of the double-column ASU modeling. In this paper, a simultaneous optimization and integration methodology is developed for the system of ASU and GT to increase the net power generation. The rigorous mathematical model of ASU and GT is proposed as the basics. Some novel simplifications of ASU, such as the limiting temperature difference of heat transfer, are proposed to increase the model flexibility with same energy prediction accuracy. After the validation through the base case, two improved case are introduced and shows additional 10% and 14% power output increment compared with the current industrial practice (base case).

A novel LNG cryogenic energy utilization method for inlet air cooling to improve the performance of combined cycle

A novel liquefied natural gas (LNG) cryogenic energy utilization method for gas turbine inlet air cooling is proposed in this work. In this method, the temperature difference potential between LNG and cooling medium is utilized step by step. The novel cold production process consists of a CO2 Rankine cycle subsystem and a CO2 compression–refrigeration subsystem. A sensitivity analysis is performed to optimize the performance of the proposed novel cold production process. Results show that the cold energy output of the novel process is increased by about 36.5%, compared with that of the conventional cold production process via direct LNG evaporation. The off-design performance of the gas turbine combined cycle under different ambient conditions is also analyzed to identify the effect of the cold production process for inlet air cooling on a combined cycle power plant. The results indicated that by applying the novel cold production method for inlet air cooling, the combined cycle relative power output increment varies from 1.6% to 11.6%, when air humidity changes from 90% to 30%, compared with that without inlet air cooling. The combined cycle relative power and relative efficiency by the novel air cooling is by 0.50–2.47% and 0–0.11%, respectively, higher than that by conventional inlet air cooling. The novel cold production process is beneficial to the augmentation of cold energy output and combined cycle power output. However, there is no significant difference in the combined cycle efficiency between the novel and the conventional power systems.

Effects of 4 Weeks of High-Intensity Interval Training and β-Hydroxy-β-Methylbutyric Free Acid Supplementation on the Onset of Neuromuscular Fatigue

This study investigated the effects of high-intensity interval training (HIIT) and β-hydroxy-β-methylbutyric free acid (HMB) supplementation on physical working capacity at the onset of neuromuscular fatigue threshold (PWC(FT)). Thirty-seven participants (22 men, 15 women; 22.8 ± 3.4 years) completed an incremental cycle ergometer test (graded exercise test [GXT]); electromyographic amplitude from the right vastus lateralis was recorded. Assessments occurred preceding (PRE) and after 4 weeks of supplementation (POST). Participants were randomly assigned to control (C, n = 9), placebo (P, n = 14), or supplementation (S, n = 14) groups. Both P and S completed 12 HIIT sessions, whereas C maintained normal diet and activity patterns. The PWC(FT) (W) was determined using the maximal perpendicular distance (D(MAX)) method. Electromyographic amplitude (μVrms) over time was used to generate a cubic regression. Onset of fatigue (TF) was the x-value of the point on the regression that was at D(MAX) from a line between the first and last data points. The PWC(FT) was estimated using TF and GXT power-output increments. The 2-way analysis of variance (ANOVA) (group × time) resulted in a significant interaction for PWC(FT) (F = 6.69, p = 0.004). Post hoc analysis with 1-way ANOVA resulted in no difference in PWC(FT) among groups at PRE (F = 0.87, p = 0.43); however, a difference in PWC(FT) was shown for POST (F = 5.46, p = 0.009). Post hoc analysis among POST values revealed significant differences between S and both P (p = 0.034) and C (p = 0.003). No differences (p = 0.226) were noted between P and C. Paired samples t-tests detected significant changes after HIIT for S (p < 0.001) and P (p = 0.016), but no change in C (p = 0.473). High-intensity interval training increased PWC(FT), but HMB with HIIT was more effective than HIIT alone. Furthermore, it seems that adding HMB supplementation with HIIT in untrained men and women may further improve endurance performance measures.

Higher rate of fat oxidation during rowing compared with cycling ergometer exercise across a range of exercise intensities.

The relative contribution of carbohydrate and fat oxidation to energy expenditure during exercise is dependent on variables including exercise intensity, mode, and recruited muscle mass. This study investigated patterns of substrate utilization during two non-weightbearing exercise modalities, namely cycling and rowing. Thirteen young, moderately trained males performed a continuous incremental (3-min stages) exercise test to exhaustion on separate occasions on an electronically braked cycle (CYC) ergometer and an air-braked rowing (ROW) ergometer, respectively. On two further occasions, participants performed a 20-min steady-state exercise bout at ∼50%VO2peak on the respective modalities. Despite similar oxygen consumption, rates of fat oxidation (FATox ) were ∼45% higher during ROW compared with CYC (P < 0.05) across a range of power output increments. The crossover point for substrate utilization occurred at a higher relative exercise intensity for ROW than CYC (57.8 ± 2.1 vs 42.1 ± 3.6%VO2peak , P < 0.05). During steady-state submaximal exercise, the higher FATox during ROW compared with CYC was maintained (P < 0.05), but absolute FATox were 42% (CYC) and 28% (ROW) lower than during incremental exercise. FATox is higher during ROW compared with CYC exercise across a range of exercise intensities matched for energy expenditure, and is likely as a consequence of larger muscle mass recruited during ROW.

Performance investigation of a power augmented vertical axis wind turbine for urban high-rise application

A shrouded wind turbine system has a number of potential advantages over the conventional wind turbine. A novel power-augmentation-guide-vane (PAGV) that surrounds a Sistan wind turbine was designed to improve the wind rotor performance by increasing the on-coming wind speed and guiding it to an optimum flow angle before it interacts with the rotor blades. The integration of the PAGV into the 3-in-1 wind, solar and rain water harvester on high-rise buildings has been illustrated. A particular concern related to public safety is minimized when the wind turbine is contained inside the PAGV and noise pollution can be reduced due to the enclosure. Besides, the design of the PAGV that blends into the building architecture can be aesthetic as well. Moreover, a mesh can be mounted around the PAGV to prevent the bird-strike problem. From the wind tunnel testing measurements where the wind turbine is under free-running condition (only rotor inertia and bearing friction were applied), the wind rotor rotational speed (with the PAGV) was increased by 75.16%. Meanwhile, a computational fluid dynamics (CFD) simulation shows that the rotor torque was increased by 2.88 times with the introduction of the PAGV. Through a semi-empirical method, the power output increment of the rotor with the PAGV was 5.8 times at the wind speed of 3 m/s. Also, the flow vector visualization (CFD) shows that a larger area of upstream flow was induced through the rotor with the PAGV.

Gender differences in whole-body fat oxidation kinetics during exercise

Discrepancies appear in studies comparing fat oxidation between men and women. Therefore, this study aimed to quantitatively describe and compare whole-body fat oxidation kinetics between genders during exercise, using a sinusoidal (SIN) model. Twelve men and 11 women matched for age, body mass index, and aerobic fitness (maximal oxygen uptake and maximal power output per kilogram of fat-free mass (FFM)) performed submaximal incremental tests (Incr) with 5-min stages and a 7.5% maximal power output increment on a cycle ergometer. Fat oxidation rates were determined using indirect calorimetry, and plotted as a function of exercise intensity. The SIN model, which includes 3 independent variables (dilatation, symmetry, translation) that account for the main quantitative characteristics of kinetics, was used to mathematically describe fat oxidation kinetics and to determine the intensity (Fatmax) eliciting the maximal fat oxidation (MFO). During Incr, women exhibited greater fat oxidation rates from 35% to 85% maximal oxygen uptake, MFO (6.6± 0.9 vs. 4.5± 0.3mg·kg FFM-1·min-1), and Fatmax (58.1%± 1.9% vs. 50.0%± 2.7% maximal oxygen uptake) than men (p< 0.05). While men and women showed similar global shapes of fat oxidation kinetics in terms of dilatation and symmetry (p> 0.05), the fat oxidation curve tended to be shifted toward higher exercise intensities in women (rightward translation, p = 0.08). These results support the idea that women have a greater reliance on fat oxidation than men during submaximal exercise, but also indicate that this greater fat oxidation is shifted toward higher exercise intensities in women than in men.

Lower muscle strength gains in older men with type 2 diabetes after resistance training

This investigation compared the effects of a twice-weekly whole-body supervised progressive resistance training program in older men with type 2 diabetes with those in healthy older men. Twenty sedentary older men participated in a 16-week progressive resistance training study. They were assigned either to a control group ( n=11) or to a type 2 diabetes group ( n=9). Lower as well as upper body maximal strength (one repetition maximum) and power testing and blood draws to determine basal hormone concentrations (total as well as free testosterone and cortisol) were conducted 4 weeks before training and then at Weeks 0 and 16. The training program consisted of intensities ranging from 50% to 80% of one repetition maximum, 5 to 15 repetitions per set, and three to four sets of each exercise. Baseline maximal muscle strength was not significantly different between groups. After training, significant differences were observed in the magnitude of increments in maximal arm strength and leg strength between the control and type 2 diabetes groups (36.7%±12.9% vs. 24.2%±4.1%, P=.04, and 35.6%±12.2% vs. 17.0%±3.8%, P<.01, respectively), whereas no significant difference was observed between groups in the power output increments of the arm and leg extensor muscles (22.5%±21.3% vs. 23.8%±18.3% and 34.2%±32.0% vs. 33.0%±21.2%, respectively). At baseline, significant differences were observed in the concentrations of total testosterone and cortisol between the control subjects and the patients with type 2 diabetes (20.3±6.0 vs. 10.6±2.9 nmol/l, P<.001, and 546.5±114.7 vs. 343.2±98.4 nmol/l, P<.001, respectively). However, no systematic change was observed during the 16-week strength training period in the basal concentrations of serum total as well as free testosterone and cortisol in both groups. In contrast, statistically significant correlations were observed in a combined group of healthy older men and older men with type 2 diabetes (H+D group) between the mean levels of individual serum total testosterone and cortisol (averaged for the entire training period) and the individual changes in maximal leg strength and arm strength ( r=0.85–0.51 and 0.63–0.70, respectively, P<.05). In summary, it would appear that older subjects with type 2 diabetes are equally trainable for muscle power output but not for maximal strength as their healthy counterparts.