Caveats and Recommendations to Assess the Validity and Reliability of Cycling Power Meters: A Systematic Scoping Review

A large number of power meters have become commercially available during the last decades to provide power output (PO) measurement. Some of these power meters were evaluated for validity in the literature. This study aimed to perform a review of the available literature on the validity of cycling power meters. PubMed, SPORTDiscus, and Google Scholar have been explored with PRISMA methodology. A total of 74 studies have been extracted for the reviewing process. Validity is a general quality of the measurement determined by the assessment of different metrological properties: Accuracy, sensitivity, repeatability, reproducibility, and robustness. Accuracy was most often studied from the metrological property (74 studies). Reproducibility was the second most studied (40 studies) property. Finally, repeatability, sensitivity, and robustness were considerably less studied with only 7, 5, and 5 studies, respectively. The SRM power meter is the most used as a gold standard in the studies. Moreover, the number of participants was very different among them, from 0 (when using a calibration rig) to 56 participants. The PO tested was up to 1700 W, whereas the pedalling cadence ranged between 40 and 180 rpm, including submaximal and maximal exercises. Other exercise conditions were tested, such as torque, position, temperature, and vibrations. This review provides some caveats and recommendations when testing the validity of a cycling power meter, including all of the metrological properties (accuracy, sensitivity, repeatability, reproducibility, and robustness) and some exercise conditions (PO range, sprint, pedalling cadence, torque, position, participant, temperature, vibration, and field test).

Desain Sensor Kelembapan Relatif Udara Menggunakan Fiber Optik

Kelembapan udara menjadi faktor penting dalam kehidupan manusia yaitu untuk menjaga kesetabilan kesehatan tubuhyang jugai akan berpengaruh kepada kenyamanan kerja. Diperlukan sensor untuk mengetahui kelembapan dalam ruangan. Alat bisa dikatakan sensor jika memiliki linearitas dan sensitivitas, dalam hal ini fiber optik cocok untuk sensor dikarenakan kemampuan alaminya yang tahan terhadap gangguan elektromagnetik, tahan terhadap suhu tinggi, memiliki sensitivitas dan fleksibelitas yang tinggi, dan dapat digunakan untuk pengukuran dan penginderaan jauh. Penelitian ini menggunakan 2 buah kabel patch core singlemode SC-SC yang dihubungkan dengan fiber coupler yang telah diberi lubang bagian tengahnya dengan diameter 1mm dan diberi jarak antar ferullenya sebasar 0.3mm, 0.6mm, 0.8mm, 1mm. Optical light source digunakan untuk memberikan masukan dengan nilai -7dBm dan nilai keluaran akan dibaca oleh Optical power meter yang nantinya akan diolah menjadi loss daya kemudian dibandingkan dengan nilai kelembapan relatif dari Hygrometer dan akan diperoleh persamaan linearnya. Hasil pengukuran didapatkan semakin jauh jarak antar ferulle maka range yang didapat juga akan semakin panjang. Range terpanjang didapat pada pengukuran jarak 1mm dengan selisih loss daya sebesar 0.2dB dan range terpendek didapat pada pengukuran 0.3mm dengan selisih loss daya sebesar 0.08dB.

Performance evaluation of polycrystalline photovoltaic modules in a Guinea Savanna and Mangrove swamp

This central idea of this research is to investigate how voltage, current, power output and efficiency of polycrystalline photovoltaic (PV) modules installed in a Guinea Savanna and Mangrove Swamp is affected by temperature, relative humidity and irradiance. The study locations are Calabar (mangrove swamp) and Ogoja (guinea savanna), in Cross River State, Nigeria. Two polycrystalline PV modules of exact specification mounted on a platform one-metre-high above the ground were used. A digital solar power meter (SM206) and a digital solar flux meter (MS 6616) was used to monitor and measure solar power and solar flux reaching the PV modules. A digital hygrometer and thermometer (KT-908) were used to monitor and measure the relative humidity and ambient temperature level at the height of installation and a digital multimeter (M880C+) accompanied with a temperature sensor was used to monitor voltage, current and panel temperature values from the modules. Analysis of the collected data reveals that the efficiency of the modules were not constant throughout the day. However, a higher voltage production and efficiency level was obtained for the PV module installed in Ogoja than that installed in Calabar under their respective levels of relative humidity, temperature and irradiance.

Appropriate assessment of disparity in some electrical parameters of selected bulbs

The complaints, worries and dissatisfactions accrued to bulb users prompted the quest of this research. The objective of the research is to suitably assess few electrical parameters of bulbs available in the market in order to have an experimental proof of the disparity in their ratings. In the research experimental data, incandescent bulbs (100W and 200W), LED bulb (5W) and CFL bulb (40W) (of different powers) were selected for evaluation. The power and lux of the bulbs were measured and compared correspondingly using the incandescent bulbs as reference bulbs for lux comparison. The new double T8 full range & ac/dc power meter with dimmer was instrument used to measure power and other associated electrical parameters (current and voltage) of the bulbs. The measurement results show that incandescent bulb of 100W measured 60.1W and the 200W measured 184.0W. The power of the 5W LED and 40W CFL bulbs measured 7.2W and 22.2W respectively. On this note, it is invariably obvious that there exists disparity in power rating of the bulbs accessible in our present day market. The digital luxmetre was used to measure lux (luminous flux per unit area or lumen per metre square) of the bulbs. In the lux measurement, the luxmetre’s sensor was placed 50cm away from the bulb’s position to obtain exact or close values to original bulbs’ lux. Consequential to the bulbs lux comparisons, the lux value of 5W LED and 40W CFL bulbs have illuminances of 507lm/m2 and 568lm/m2 respectively higher than lux of 100W incandescent bulb. Hence, lux values of the LED and CFL bulbs measurements fall in-between lux values of 100W and 200W incandescent bulbs. Critical evaluation of the results tends to establish that luminosity (luminous flux per area) of bulb does not depend on power.

Reliability and Validity of the SHFT Running Power Meter

The SHFT device is a novel running wearable consisting of two pods connected to your smartphone issuing several running metrics based on accelerometer and gyroscope technology. The purpose of this study was to investigate the reliability and validity of the power output (PO) metric produced by the SHFT device. To assess reliability, 12 men ran on an outdoor track at 10.5 km·h−1 and 12 km·h−1 on two consecutive days. To assess validity, oxygen uptake (VO2) and SHFT data from eight men and seven women were collected during incremental submaximal running tests on an indoor treadmill on one to four separate days (34 tests in total). SHFT reliability on the outdoor track was strong with coefficients of variance (CV) of 1.8% and 2.4% for 10.5 and 12 km·h−1, respectively. We observed a very strong linear relationship between PO and VO2 (r2 = 0.54) within subjects, and a very strong linear relationship within each subject within each treadmill test (r2 = 0.80). We conclude that SHFT provides a reliable running power estimate and that a very strong relationship between SHFT-Power and metabolic rate exists, which places SHFT as one of the leading commercially available running power meters.

Analysis of the Impact of Distance and Temperature in Determining Transfer Power Using Laser Applications

This article aimed to analyze the impact of distance and temperature in determining transfer power using laser applications. This study used instruments consisting of a power meter, photovoltaic, laser, and DC power supply. This research was using experimental method. The impact of distance and temperature in determining transfer power using laser applications was concluded based on the results of calculation analysis, measurements of photovoltaic output power, distance, temperature, and laser input power. The impact of distance and temperature in determining transfer power using laser applications showed that the probability value or p-value was lower than the error/alpha level (a) (2.207E-18 <0.05). Likewise, the calculated F value is greater than the significance F (15290048>4.68386E-27). With the applicable provisions in testing the hypothesis, that the conclusion in this article rejected the null hypothesis (H0 : The distance and temperature have not an impact in determining transfer power using laser applications), and accepted the alternative hypothesis (H1:The distance and temperature have an impact in determining transfer power using laser applications).

Specific Mixing Energy of Cemented Paste Backfill, Part I: Laboratory Determination and Influence on the Consistency

Slump determination is widely used to assess the consistency and transportability of fresh cemented paste backfill (CPB). CPB consistency can depend on the mixing procedure for CPB preparation. In this paper, a method was developed to determine the specific mixing energy (SME) that is dissipated during the preparation of CPB mixtures and to analyze its effect on CPB consistency. For this purpose, CPB recipes were prepared using two tailings and the mixing parameters (mixing time and speed and load mass) were successively varied. SME was determined for each mixture using a power meter equipped with an energy recording system mounted on a laboratory Omcan mixer. Slump was also determined for each mixture. A semi-empirical model was then developed to predict SME as a function of the mixing parameters. Results showed that predicted SME compared well with measured SME during CPB preparation. Results also showed that slump increased with increasing SME. The influence of SME on the rheological and mechanical properties of CPB and practical applications are presented in a companion paper.

Sampling Rate Impact on Electrical Power Measurements Based on Conservative Power Theory

This article presents a study of the sampling rate effect on electrical power measurements whose definitions are based on the Conservative Power Theory (CPT). The definitions of active power and reactive power of the CPT were applied in the MATLAB® software by varying the sampling rate and using a digital power meter as a reference. The measurements were performed in scenarios with linear and non-linear loads. Due to the usage of an integral in the CPT calculus, an error was verified associated with the reactive power being inversely proportional to the sampling rate. From the present study, it is possible to conclude that depending on the sample rate, the errors associated with the reactive power measurements are unacceptable and make the CPT implementation unfeasible. The results also presented effective information about the minimal sampling rate needed to make these errors neglected and to assist in choosing suitable microprocessors for the digital implementation of the CPT. It is worth mentioning that this paper was limited to assess how accurate the measurements of active and reactive powers were and important to highlight that the CPT has the additional contribution of dealing with distortion currents and consequently new portions of powers. For the latter, the influence of sampling rate may be crucial and new lines of investigation are motivated.