Max Power Research Articles

Metal Bipolar Plate with Micro Sensors

The fuel cell has the potential to become an indispensable source of electric power. However, some problems have not yet been resolved. Measuring the temperature and humidity inside the fuel cells is currently difficult. Accordingly, in this study, micro sensors were fabricated within the fuel cell, in which the temperature and humidity distributions were measured. The substrate of the fuel cell was made of stainless steel (SS-304) and etching was employed to fabricate the channel on the stainless steel substrate. Then micro-electro-mechanical-systems (MEMS) technology was used to fabricate the array micro temperature and humidity sensors on the rib of channel of stainless steel. The advantages of array micro temperature sensors are their small volume, their high accuracy, their short response time, the simplicity of their fabrication, their mass production and their ability to measure the temperature at a precise location more effectively than the traditional thermocouple. The micro humidity sensors were made from gold and titanium as down and up electrodes in the channel. The performance curve of the single cell was operating at 41.54 °C and gas flow rates of H2/O2 at 200/200ml/min. The max power density of the bipolar with micro sensor was 56 mW/cm2.

Percutaneous radiofrequency ablation of lung tumours: results in the mid-term☆

Radiofrequency ablation (RFA) of lung tumours has recently received much attention for the promising results achieved. Herein, we report the 5 years experience of a single referral centre in Europe, with particular reference to the mid-term results. Between October 2001 and June 2005, we performed 88 RFAs of lung tumours, 9 of which were followed by surgical resection. The remaining 79 RFAs, the object of this paper, were performed to treat 64 lesions in 54 patients: 39 males and 15 females with a mean age of 71.7 years (range of 51-89). All patients had clinical or pathological evidence of the neoplastic lesion, which was non-small cell lung cancer (NSCLC) in 40 cases and a metastasis in 24 cases. The mean size of the lesions was 2.4 cm (range of 1-5). Ten lesions were re-treated from one to as many as four times. The procedure was always performed under local anaesthesia and conscious sedation. A generator of RF with max power output of 200W was utilised together with a needle with nine deployable electrodes, to achieve a target temperature of 90 degrees C that was maintained for 15-27 min according to the size of the lesions. In all cases, except two, the procedure was technically successful. Morbidity consisted in 10 cases (12.7%) of partial pneumothorax, 1 haematoma of the chest wall and 1 pleural effusion. At a mean follow-up of 23.7 months (range of 6-50) we recorded a 61.9% of complete responses, with a higher rate in the metastatic lesions (70.8%) and in those smaller than 3 cm (69.7%). Mean (median) overall survival and local progression-free interval were 17.3 (28.9) months and 12.9 (24.1) months, respectively. Efficacy of RFA in the mid-term seems to settle at a promising level, with better results for metastatic lesions and, above all, for lesions smaller than 3 cm. Notwithstanding these encouraging results, RFA remains an alternative local therapy only when surgery cannot be performed, especially in NSCLC.

Two Critical Concept Indexes, Combining With Different Physiological Variables, In Predicting 2000m Indoor Rowing Performance

Critical velocity (CV) and critical power (CP) have been proposed to be effective indirect anaerobic threshold methods in monitoring training and predicting performance of rowing, respectively. However, which index is the most proper one when applying critical concept in rowing performance is not clear. Purpose To compare the two indexes in predicting indoor rowing performance by combining different physiological variables, including maximal oxygen uptake (VO2max), anaerobic threshold (OBLA) and modified Wingate test, which are important physiological variables in endurance performance. Method Fifteen elite female rowers (age 20.7 ± 1.4 years, height 1.64 ± 0.35m, weight 56.64 ± 4.38kg) were recruited in this study. VO2max (43.31 ± 5.25ml/kg/min) and OBLA (157.81 ± 22.08W) were measured during a discontinuous graded exercise test, starting at 100W, on a Concept II ergometer increased by 25 W for each 3 min stage. Four test times of duration 90s, 240s, 600s, and 1200s were used to determine CP (139.49 ± 20.37W), and CV(4.00 ± 0.14m/s) was estimated by 400m, 600m, 800m, 1000m maximal exertion trials on different days as well by using Linear distance-time model. Peak power (353.48 ± 27.71W), maximum power (350.12 ± 26.72W), minimum power (336.85 ± 21.58W), mean power (314.44 ± 27.87W), fatigue index [(max power – min power)/mean power] were obtained using a modified Wingate test protocol (30s sprint) on the ergometer. Result The results showed that VO2max, OBLA, CP, CV, peak power, mean power were significantly correlated with 2000m indoor rowing performance (r=−0.84, −0.85, −0.81, −0.97, −0.66, −0.67, p<0.01). By submitting mean power, fatigue index, VO2max, OBLA with each index to a stepwise regression analysis, it produced two individual critical concept models as following to predict 2000m indoor rowing performance:CV model: Time for 2000m=−131.44(CV)-89.57(fatigue) index+1022.27 (R2 = 0.96, SEE=4.08, p<0.05); CP model: Time for 2000m = −0.445(OBLA) −1.853(VO2max) +643.98 (R2 = 0.84, SEE=7.75, p<0.05). Conclusion Our findings in this study indicated that in the CV model, CV has more predictive power, represented as anaerobic threshold, than OBLA to predict rowing performance. Besides CV, fatigue index from modified Wingate test explains an additional 15 % variance in rowing performance. Therefore, compared with CP, CV could be used when applying critical concept in training and evaluate indoor performance in rowing.

Corneal refractive power measurement with Orbscan-II topography system versus keratometer

目的 探讨角膜曲率计和角膜地形图检查系统测量角膜屈光力的差异.方法随机选取我院屈光手术门诊LASIK术前365例(681眼),同时用两种方法测量角膜屈光力,比较二者间的差异.结果两种方法测量的最大角膜屈光力:角膜曲率计为(43.774±1.535)D和角膜地形图仪为(43.517±1.546)D,最小角膜屈光力分别为(42.756±1.430)D和(42.513±1.440)D;平均角膜屈光力分别为(43.256±1.459)D和(42.769±1.427)D.以上3组数字两两比较,差异均有非常显著意义(P＜0.001).结论角膜地形图仪所测角膜屈光力较角膜曲率计所测结果准确,LASIK术前应参考角膜地形图仪所测角膜屈光力。

The Efffect of Creatine Supplementation on Power Output During Repeated Sprint Running

1982 The effects of creatine supplementation (Cr) on sprint running performance has been studied previously by analyzing changes in sprint speed by finishing time for a sprint of desired distance with equivocal results. Some researchers have rationalized that the increase in body mass seen with creatine supplementation may inhibit increases in running speed. Therefore, sprint running leg power may increase but may not be apparent by the assessment used in previous studies. PURPOSE: To determine effects of Cr on power output during repeated sprint running. METHODS: A magnetically braked treadmill was used to determine leg power during maximal sprint running protocol that consisted of 2 sets of 6 × 6 sec sprints with 45 sec between sprints and 5 min of walking between sets. Subjects were 2 groups of 7 Division III football and soccer players that were familiar with the treadmill and protocol. After initial visit, subjects were randomly placed in 2 doubleblinded groups (Placebo or Cr). Each subject performed the protocol at 2 different trials (T1 and T2) separated by 7 days. The first trial followed 6 days of supplementation with a placebo. The second trial followed 6 days of supplementation with the placebo or Cr. Alpha level was set at p<0.05. RESULTS: No Group × Trial interactions were observed. Differences by Trial were found for minimum (min) power (T1 = 741.1 ± 25.5, T2 = 767.6 ± 24.9 W) and DELTA power (Max power − Min Power) (T1 = 68.3 ± 8.8, T2 = 48.1 ± 3.7 W). Trial differences were also found by bodyweight (T1 = 88.1 ± 3.1, T2 = 89.0 ± 3.1 kg), relative min power (T1 = 8.45 ± 0.23, T2 = 8.67 ± 0.22 W/kg), and relative DELTA power (T1 = 0.771 ± 0.091, T2 = 0.538 ± 0.035 W/kg). CONCLUSION: Creatine supplementation did not enhance repeat sprint running power production in this group of Division III athletes.

Maximal Lactate Steady State Rowing Intensity can be Predicted by a 6-Km Rowing Time Trial

0298 It has been suggested that endurance training at intensities approximating maximal lactate steady state (MLSS) may heighten exercise adaptations while minimizing the risk of overtraining related injuries. Measuring MLSS in the laboratory is labor intensive, as laboratory equipment, technicians, and a substantial time investment are all required for invasive physiological testing. Conversely, athletic time trial events are often completed in endurance sports and are relatively simple. If rowers were able to predict MLSS workload from a time trial, it would become comparatively simple for more athletes to become aware of their MLSS workload. PURPOSE: To test the hypothesis that a relationship exists between the average workload during a 6-km rowing time trial and the MLSS workload. METHODS: Female athletes (n = 23) from a varsity Division I collegiate rowing team were utilized as subjects (age 20.1 ± 1.1yrs, weight 72.0 ± 7.4 kg, height 162.6 ± 6.6 cm, VO2 peak 46.6 ± 3.7 ml/kg/min). Athletes underwent a maximal power output test on the rowing ergometer (max power 263.3 ± 27.5 W). To determine MLSS, each subject completed two to four 30-minute constant workload rows at intensities relative to their individual maximal power output. To eliminate test interruptions, blood samples were collected via toe stick at rest and every 5 minutes during the 30-minute rows. The criterion for achievement of MLSS was the highest concentration of blood lactate that could be maintained (± 1 mM) during the last 20 minutes of a 30-minute constant workload rows (mean MLSS 2.59 ± 0.62 mM). Subsequently, each rower completed a 6-km time trial where mean power output was recorded. RESULTS: There was a significant correlation between 6-km time trial mean power output and the power output at MLSS (r = 0.92, p<0.0001). However, 6-km time trial mean power output (214.4 ± 22.9 W) was significantly greater than the power output at MLSS (168.3 ± 19.1W). Hence, the power output at MLSS was equivalent to 78.5% of the 6-km time trial mean power output. CONCLUSIONS: The hypothesis that completion of a 6-km time trial would predict MLSS power output was supported. In rowers, as MLSS workload increases, time to complete the 6-km time trial decreases. Furthermore, this suggests that training to improve MLSS workload may improve 6-km rowing performance. Supported in part by Abbott Laboratories.

エンジン性能の改善された総合理論分析 : 出力重視と燃費重視の理論把握(一般セッション 伝熱解析及び理論 I)

エンジン性能の改善された総合理論分析 : 出力重視と燃費重視の理論把握(一般セッション 伝熱解析及び理論 I)

THE EFFECT OF CYCLING POSITION ON ECONOMY AND CADENCE DURING HILL CLIMBING AT VARIOUS POWER OUTPUTS

Purpose: The purposes of this study were to examine the effect of various power outputs and cycling positions have on cycling economy and cadence during hill climbing on the road. Methods: Thirteen trained cyclists reported to the laboratory for a VO2 max test. Subjects then completed seven hill climbing trials during a single test session. Trials were performed seated and standing at 50, 65, and 75% of max power output, followed by one maximal time trial (TT). During the last trial, subjects were allowed to change position as desired. Results: To date, 8 subjects have completed testing. Their mean VO2 max was 4.75 + 0.07 L.min-1, while maximal aerobic power output (MPO) was 407 + 61 W. Economy and cadence while standing were 77 + 4 W.L-1 and 57 + 3 rpm at 50% MPO, 81 + 2 W.L-1 and 62 + 2 rpm at 65% MPO, and 85 + 2 W.L-1 and 66 + 2 rpm at 75% MPO. Economy and cadence while sitting were 75 + 2 W.L.-1 and 75 + 2 rpm at 50% MPO, 80 + 1 W.L-1 and 81 + 2 rpm at 65% MPO, and 83 + 2 W.L-1 and 88 + 1 rpm at 75% MPO. During the maximal TT, economy and cadence were 99 + 3 W.L-1 and 78 + 3 rpm, respectively, and corresponded to 93.5 + 1.6% MPO. Conclusions: These data suggest that there are no differences in economy between seated and standing climbing, despite a significant difference in cadence.

The Effects of Varying Dietary Fat on Performance and Metabolism in Trained Male and Female Runners

Objectives: Low dietary fat intake has become the diet of choice for many athletes. Recent studies in animals and humans suggest that a high fat diet may increase V̇o2 max and endurance. We studied the effects of a low, medium and high fat diet on performance and metabolism in runners.Methods: Twelve male and 13 female runners (42 miles/week) ate diets of 16% and 31% fat for four weeks. Six males and six females increased their fat intakes to 44%. All diets were designed to be isocaloric. Endurance and V̇o2 max were tested at the end of each diet. Plasma levels of lactate, pyruvate, glucose, glycerol, and triglycerides were measured before and after the V̇o2 max and endurance runs. Free fatty acids were measured during the V̇o2 max and endurance runs.Results: Runners on the low fat diet ate 19% fewer calories than on the medium or high fat diets. Body weight, percent body fat (males=71 kg and 16%; females=57 kg and 19%), V̇o2 max and anaerobic power were not affected by the level of dietary fat. Endurance time increased from the low fat to medium fat diet by 14%. No differences were seen in plasma lactate, glucose, glycerol, triglycerides and fatty acids when comparing the low versus the medium fat diet. Subjects who increased dietary fat to 44% had higher plasma pyruvate (46%) and lower lactate levels (39%) after the endurance run.Conclusion: These results suggest that runners on a low fat diet consume fewer calories and have reduced endurance performance than on a medium or high fat diet. A high fat diet, providing sufficient total calories, does not compromise anaerobic power.

The Technology of Max Power Control for Micro Wind Turbine

The Technology of Max Power Control for Micro Wind Turbine

Supervisory control of autogenous grinding circuits

At Boliden Mineral's Aitik concentrator approx 16 Mtpy is milled in five parallel fully autogenous grinding circuits. The original maximum throughput control strategy lead to overruns of the primary mills. Tests showed peak throughput at mill power lower than max power. The peak power varies due to variable ore grindability implying a need for continuous adjustment of the millpower setpoint. The main control functions are mill power setpoint optimization and ore feed control. The power optimization loop finds the optimum power setpoint, related to the ore grindability, giving the highest possible throughput. The control system has improved the milling capacity by approx. 5%.

Wind power potential over Delhi

An attempt is made to investigate in the field of renewable source of wind energy available in nature by estimating the wind power potential over Delhi and it~ effective utilisation for windmills for different speed ranges. Frequency and wind speed fine spectral analysis indicates that windmills designed for upper light wind range. (6 to 8 km/hr) can be effectively put into operation during the daytime for about 8-12 hrs., the time depending upon the month and the range of the wind speed at which the windmill can be operated. The max power potential over Delhi varies from 720 watt hr/m2/day during the months of March to min. of 130 watt hr/m2/day in the month of November.

Endurance training does not affect diaphragm mitochondria respiration

We sought to determine if chronic endurance training would increase mitochondrial respiration or protein content in rat diaphragm muscle. To this end, 20 male Wistar rats were randomly assigned to control (C) or an 8-week endurance training (T) group, n = 10 per group. At the end of T, V̇ O 2 max was 13% greater in T (83.3 vs 73.8 ml·kg −1·min −1) and peak max power output was 32% greater (2.63 vs 1.98 kg·m·min −1). Mitochondrial specific activities of pyruvate-malate and cytochrome oxidase (expressed per mg mitochondrial protein) in both plantaris and diaphragm were similar in C and T rats, as were ADP/O and respiratory control ratios. When expressed per gram wet weight, whole muscle homogenate oxygen uptake (pyruvate + malate) and cytochrome oxidase activity increased 36 and 23%, respectively ( P < 0.05) in plantaris from T rats but did not change in diaphragm. Control oxidative capacity and mitochondrial protein content in the diaphragm were ca. 2-fold those in control plantaris. Plantaris mitochondrial protein content increased ca. 50% with T while the diaphragm was unaffected. We conclude that: (1) plantaris muscle oxidative capacity adapts to training by increasing mitochondrial protein content, since there was no evidence for functional improvement of existing mitochondria, and (2) in the face of a substantial training effect in whole animal and plantaris, the T stimulus was not sufficient to induce mitochondria protein changes in the diaphragm. This finding is the result of either a ‘pre-adaptation’ secondary to the diaphragm's high chronic activity, or a sub-threshold increase in diaphragn recruitment during the exercise conditions studied.

Reduction des interferences sur la determination des metaux lourds dans les sediments de cours d'eau et les boues de stations d'epuration par spectrometrie d'absorption atomique en four graphite

(Reduction of interferences in the determination of trace heavy metals in river sediments and sewage sludges by electrothermal atomic absorption spectrometry.) The interferences of synthetic matrices of river sediments and sewage sludges in the determination of lead, copper, cadmium, chromium and nickel by electrothermal atomic absorption spectrometry were studied; Pb, Cd and Ni were the most sensitive to interferences. The effects of hydrochloric, nitric, perchloric and hydrofluoric acids were tested; perchloric acid was found to interfere most during the determinations. Hydrofluoric acid must be eliminated by evaporation. Techniques for reducing chemical interferences were evaluated. The best method was found to be matrix modification with ammonium dihydrogenphosphate and ascorbic acid for the determination of lead and nickel, and rapid heating (Max Power) for the determination of cadmium. Determinants of copper and chromium were less prone to interference.

EFFECTS OF METOPROLOL ON SYSTEMIC HAEMODYNAMICS, MYOCARDIAL PERFORMANCE AND THE CORONARY CIRCULATION DURING HALOTHANE ANAESTHESIA

The effects of metoprolol 1 mg kg-1 i.v. on the systemic and coronary circulations and on myocardial performance were studied in nine open-chested dogs ventilated with halothane 0.8% in oxygen at normocarbia. In terms of the chronotropic effect, this dose of metoprolol produced a substantial shift to the right of the dose-response curve to isoprenaline; substantial reductions of arterial pressure (10%), cardiac output (21%), aortic blood acceleration (13%), left ventricular dP/dt max (13%) and left ventricular power (25%) were observed. Both preload, represented by left ventricular end diastolic pressure, and afterload, represented by systemic vascular resistance, increased. Left circumflex coronary blood flow and myocardial oxygen consumption decreased by approximately the same amount as peak ventricular power.