Power Meter Research Articles

The validity and reliability of wearable devices for the measurement of vertical oscillation for running.

Wearable devices are a popular training tool to measure biomechanical performance indicators during running, including vertical oscillation (VO). VO is a contributing factor in running economy and injury risk, therefore VO feedback can have a positive impact on running performance. The validity and reliability of the VO measurements from wearable devices is crucial for them to be an effective training tool. The aims of this study were to test the validity and reliability of VO measurements from wearable devices against video analysis of a single trunk marker. Four wearable devices were compared: the INCUS NOVA, Garmin Heart Rate Monitor-Pro (HRM), Garmin Running Dynamics Pod (RDP), and Stryd Running Power Meter Footpod (Footpod). Fifteen participants completed treadmill running at five different self-selected speeds for one minute at each speed. Each speed interval was completed twice. VO was recorded simultaneously by video and the wearables devices. There was significant effect of measurement method on VO (p < 0.001), with the NOVA and Footpod underestimating VO compared to video analysis, while the HRM and RDP overestimated. Although there were significant differences in the average VO values, all devices were significantly correlated with the video analysis (R > = 0.51, p < 0.001). Significant agreement between repeated VO measurements for all devices, revealed the devices to be reliable (ICC > = 0.948, p < 0.001). There was also significant agreement for VO measurements between each device and the video analysis (ICC > = 0.731, p < = 0.001), therefore validating the devices for VO measurement during running. These results demonstrate that wearable devices are valid and reliable tools to detect changes in VO during running. However, VO measurements varied significantly between the different wearables tested and this should be considered when comparing VO values between devices.

SISTEM MONITORING NILAI PARAMETER PADA POWER METER DM6200 BERBASIS INTERNET OF THINGS (IoT) SECARA REALTIME

Power Meter really supports the measurement of the electrical value of an electrical installation. The location of the Power Meter is usually installed on the main panel of a building that has 3 phase electricity. In this Power Meter has many electrical values that can be taken such as voltage, current, power factor, percentage etc. The parameter value is displayed on the Power Meter screen to see it, you need to look for the value it is located by looking at the guide in the Manual Book. In addition to these problems, data retrieval must go to the place where the Power Meter is installed, namely on the main electricity panel, from this problem the researcher makes a solution in the form of a parameter monitoring system that is displayed on the Internet of Things (IoT)-based Power Meter in Realtime. The results of this study are a monitoring tool and system, this tool has 3 main features, namely monitoring the Voltage, Current, and Power Meter parameters, sending the displayed value from the Power Meter through RS485 to TTL and programmed using the ESP32 platform then sent back to the Blynk server and will accessed with the Blynk app. The data sent can be viewed in real time via a smartphone. Of the 3 parameter values can be monitored directly with the Blynk application.

Performance of solar panels at various depths in stationary water

Photovoltaic Solar systems have become attractive for powering autonomous systems and various devices. So far, the installation and usage of solar photovoltaic systems has been limited to either land or space. Lately, underwater solar photovoltaic power generation has attracted interest due to some of its unique application in powering underwater devices. The thermal control and cooling that result makes it more dependable for underwater devices. Around the equator, and some other parts of the world, some regions can be quite hot compromising a panel performance. A systematic study on the performance of stationary under water panel using normal tap water would provide information on the applicability of underwater panels in such places. In this work, a detailed study was carried out to determine the performance of 20W monocrystalline photovoltaic solar panels locally acquired and placed at various water depths. A locally purchased plastic translucent water tank was filled with normal tap water and the panels placed in the water at various depths. Solar irradiance, ambient and panel temperature were obtained using a solar 02 device and an irradiance power meter which were connected to a solar current-voltage (I-V) analyzer. Data was collected at 30-minute intervals between 11:00 a.m. and 3:00 p.m. East African Time (EAT) for panels at different depths up to 0.6m. The results revealed that as the water depth increased form 0 m to 0.6m, the panel temperature reduced by 15.48% (at a rate of 0.062 °C/cm), ambient temperature decreased by 5.13%, solar irradiance decreased by 63.79% while power output decreased by 75.00 %. It was noted that the submerged photovoltaic panels reduced the cleaning problem and power loss caused by high temperature. However, positioning the panels deep reduces the power production due to decreased irradiance which has a strong effect on the photocurrent and hence the power production of the panel. It is therefore advisable to keep the panels just below the water surface to maximize power production. The set up can be applied in very hot places for better power production.

High power test of the power coupler for 325 MHz superconducting cavities with standing waves

The fabricated power coupler is a coaxial capacitive-type coupler based on a conventional 3 1/8-inch Electronic Industries Alliance 50-Ω coaxial transmission line with a titanium nitride (TiN)-coated ceramic disk window. A high-power test in a standing wave was performed with the 20 kW and 325 MHz solid-state power amplifier (SSPA). The standing wave test is similar to the RF conditioning condition of the cavity before beam operation. It is also possible to adjust the position of the maximum power applied to the power coupler. Two power couplers were connected to a rectangular test cavity with a high vacuum and various measuring equipment, such as an arc detector, a power meter, a temperature sensor, and an electron pick-up probe. The interlock system under vacuum and arc instrumentation prevented the RF window from breaking the power coupler window during the high-power test. The interlock system was operated when the temperature, arc discharge, and electron emission were measured and exceeded the threshold. We conducted high-power tests at 3 kW in a standing wave to verify the performance of the fabricated power coupler. In this paper, we present the results of the high-power test with standing waves using movable shorts.

Error Analysis of Digital Electric Energy Metering Based on FPGA

With the emergence and development of smart grid, digital meters have been widely used in substations, so the research on digital energy metering error has become a research hotspot. The purpose of this paper is to analyze the error of digital power measurement based on FPGA, mainly take the analog input fusion module and digital power meter in the digital power measurement system as the research object, and analyze the source of measurement error. An FPGA-based energy metering error detection platform is built to analyze the energy metering error when there are harmonics in the full energy metering method currently used by most digital energy meter manufacturers. The comparative analysis of numerical integration algorithms shows that the asymmetric distortion rates of the simulated waveforms are approximate. The results of measurement error analysis under harmonic conditions show that when the number of sampling points per cycle is 60, the power measurement errors of the 2nd to 4th harmonics are equivalent. The magnitude of the measurement error is still consistent with other low-order harmonics, and the simulation results are consistent with the theoretical analysis results.

Open-Path Ghost Spectroscopy Based on Hadamard Modulation

In order to achieve spectral detection in free space, an open-path ghost spectroscopy (GS) based on complementary Hadamard modulation is proposed. In the proposed system, a programmable spectral filter is used to modulate a series of Hadamard patterns to a broadband signal provided by an amplified spontaneous emission (ASE) source, and the spectrum-under-test is recovered by cross correlation between the power measured by an optical power meter and the Hadamard patterns. Both the simulation and experiment are carried out, and the highest spectral resolution up to 0.126 nm is achieved. Furthermore, the detection performance of the GS in a designed strong turbulence path is also demonstrated, which shows that the proposed GS is a promising solution to recover the optical spectrum in the condition of weak light and strong turbulence in the open path.

Low Frequency Terahertz Induced Thermoacoustic Signal Characteristics and Its Application in Solid-State Terahertz Transmitter Power Detection

According to the 2019 Federal Communications Commission (FCC) standard, the spectrum range of 6G is 95 GHz to 3 THz. Due to the higher density of 6G base station, a portable, low-cost, and real-time power detection method for transmitters is urgently needed. Therefore, we propose a real-time terahertz (THz) power detection method based on terahertz-thermoacoustic (THz-TA) effect. Using a homemade solid-state THz transmitter (center frequency = 170 GHz, maximum output power = 92.8 mW), we investigate the relationship between THz power, pulsewidth, and THz induced thermoacoustic signal, respectively. Compared with the test results of commercial THz power meter (Erickson-PM5), the feasibility of THz power detection based on THz-TA effect is proved. The experimental results show that the minimum THz power that THz-TA test platform can respond to is 2.8 mW, and the response time is about 0.25 seconds. In the range of 2.8 −92.8 mW, the amplitude of THz-induced TA signal is linear with the output power of solid-state THz transmitter (Pearson's <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">R</i> = 0.99571). We also note for the first time that the time interval of THz-induced TA signal is consistent with the pulsewidth of THz signal (0.5, 1, 2, and 5 μs). Therefore, THz-TA technology can not only realize the real-time detection of THz power but also measure the pulsewidth of amplitude-modulated THz signal to a certain extent. We expect that THz-TA detection method will have great potential in the real-time detection of transmitter power of 6G base station in the future.

Power Profile Index: An Adjustable Metric for Load Monitoring in Road Cycling

Workload is calculated from exercise volume and intensity. In endurance sports, intensity has been measured using heart rate or RPE, giving rise to load indexes such as sRPE or TRIMP. In cycling, the advent of power meters led to new indexes, such as TSS. All these indexes have limitations, especially for high intensity exercise. Therefore, a new index for cycling is proposed, the Power Profile Index (PPi), which includes a weighting factor obtained from the relative exercise intensity and stage type. Using power data from 67 WorldTour cyclists and fatigue records in different stage types from 102 road cyclists, weighting factors for intensity and stage type were determined. Subsequently, the PPi was computed and compared to current indexes using data from a WorldTour team during the 2018 Tour de France. The proposed index showed a strong correlation with perceived fatigue as a function of stage type (R2 = 0.9996), as well as no differences in the load quantification in different types of stage profiles (p = 0.292), something that does not occur with other indexes such as TSS, RPE, or eTRIMP (p &lt; 0.001). Therefore, PPi is a new index capable of quantifying the high intensity efforts that produce greater fatigue, as well as considering the stage type.

Improving Energy Management through Demand Response Programs for Low-Rise University Buildings

Recently, energy costs have increased significantly, and energy savings have become more important, leading to the use of different patterns to align with the characteristics of demand-side load. This paper focused on the energy management of low-rise university buildings, examining the demand response related to air conditioning and lighting by measuring the main parameters and characteristics and collecting and managing the data from these parameters and characteristics. This system seeks to control and communicate with the aim of reducing the amount of peak energy using a digital power meter installed inside the main distribution unit, with an RS-485 communication port connected to a data converter and then displayed on a computer screen. The demand response and time response were managed by power management software and an optimization model control algorithm based on using a split type of air conditioning unit. This unit had the highest energy consumption in the building as it works to provide a comfortable environment based on the temperatures inside and outside the building. There was a renewable energy source that compensated for energy usage to decrease the peak load curve when the demand was highest, mostly during business hours. An external power source providing 20 kWh of solar power was connected to an inverter and feeds power into each phase of the main distribution. This was controlled by an energy power management program using a demand response algorithm. After applying real-time intelligent control demand-side management, the efficient system presented in this research could generate energy savings of 25% based on AC control of the lighting system. A comparison of the key system parameters shows the decrease in power energy due to the use of renewable energy and the room temperature control using a combination of split-type air conditioning.

Study on mechanism of spray-mist-assisted laser processing of carbon fiber reinforced plastic

Carbon fiber reinforced plastic (CFRP) have wide application prospects due to its excellent mechanical properties. However, laser processing of CFRP will lead to a series of thermal damages, resulting in the mechanical properties being eroded. In this study, a method of spray mist to impact the wall to form a flowing and thin water film to assist laser low thermal damage processing for CFRP is carried out. Based on the oxidation reaction of oxygen to accelerate the etching efficiency of CFRP, a mixture of nitrogen and oxygen is used to assist the siphon nozzle to generate spray mist.The design of experiments (DOE) is used to study the influence of process parameters on machining, and the process parameters were optimized. The loss characteristics of spray mist on laser energy transmission were studied by the beam analyzer and the laser power meter. The dynamic ablation process of CFRP was photographed in situ by a high-speed camera, and the mechanism of spray mist-assisted laser processing of CFRP was studied by X-ray diffraction. The results show that the offset distance determines the machining quality, and the machining quality is significantly affected by laser power and cutting speed. When the oxygen content is 30%, a relative balance of cold and heat can be achieved, and a higher processing quality can be obtained. Spray mist causes laser scattering; the irradiated area and the energy loss increase; the smaller the offset distance, the larger the laser energy loss and the irradiated area. Most importantly, compared to the direct impact of the spray, the directional flow of the water film is beneficial to ensuring the quality and continuity of the laser processing.

Luminescent characteristics and mitochondrial COI barcodes of nine cohabitated Taiwanese fireflies.

Over 50 Taiwanese firefly species have been discovered, but scientists lack information regarding most of their genetics, bioluminescent features, and cohabitating phenomena. In this study, we focus on morphological species identification and phylogeny reconstructed by COI barcoding, as well as luminescent characteristics of cohabited Taiwanese firefly species to determine the key factors that influenced how distinct bioluminescent species evolved to coexist and proliferate within the same habitat. In this study, 366 specimens from nine species were collected in northern Taiwan from April to August, 2016-2019. First, the species and sex of the specimens were morphologically and genetically identified. Then, their luminescent spectra and intensities were recorded using a spectrometer and a power meter, respectively. The habitat temperature, relative humidity, and environmental light intensity were also measured. The cytochrome oxidase I (COI) gene sequence was used as a DNA barcode to reveal the phylogenetic relationships of cohabitated species. Nine species-eight adult species (Abscondita chinensis, Abscondita cerata, Aquatica ficta, Luciola curtithorax, Luciola kagiana, Luciola filiformis, Curtos sauteri, and Curtos costipennis) and one larval Pyrocoelia praetexta-were morphologically identified. The nine species could be found in April-August. Six of the eight adult species shared an overlap occurrence period in May. Luminescent spectra analysis revealed that the λ max of studied species ranged from 552-572 nm (yellow-green to orange-yellow). The average luminescent intensity range of these species was about 1.2-14 lux (182.1-2,048 nW/cm2) for males and 0.8-5.8 lux (122.8-850 nW/cm2) for females, and the maximum luminescent intensity of males was 1.01-7.26-fold higher than that of females. Compared with previous studies, this study demonstrates that different λ max, species-specific flash patterns, microhabitat choices, nocturnal activity time, and/or an isolated mating season are key factors that may lead to the species-specific courtship of cohabitated fireflies. Moreover, we estimated that the fireflies start flashing or flying when the environmental light intensity decreased to 6.49-28.1 lux. Thus, based on a rough theoretical calculation, the sensing distance between male and female fireflies might be 1.8-2.7 m apart in the dark. In addition, the mitochondrial COI barcode identified species with high resolution and suggested that most of the studied species have been placed correctly with congeners in previous phylogenies. Several cryptic species were revealed by the COI barcode with 3.27%-12.3% variation. This study renews the idea that fireflies' luminescence color originated from the green color of a Lampyridae ancestor, then red-shifted to yellow-green in Luciolinae, and further changed to orange-yellow color in some derived species.

Parallel photoreactor development with enhanced photon efficiency and reproducibility based on laws of optics

A lab-scale parallel photoreactor model has been developed for broad applications in organic chemistry. Position, angle, and distance in the reactor are systematically optimized for achieving high reproducibility under the guidance of the Inverse Square Law and Lambert’s Cosine Law, which were first applied in the design of the photoreactor. Improvement of photon efficiency is realized via 3-point irradiation and broad-band light reflector of aluminum. Photon flux is measured with an optical power meter with its display and adjustment suggested being integrated into the photoreactor for the first time.

Highly Selective Photocatalytic Conversion of Glucose on Holo-Symmetrically Spherical Three-Dimensionally Ordered Macroporous Heterojunction Photonic Crystal

Highly Selective Photocatalytic Conversion of Glucose on Holo-Symmetrically Spherical Three-Dimensionally Ordered Macroporous Heterojunction Photonic Crystal

A PON Monitoring System Integrating Fault Detection and Localization

We propose and experimentally demonstrate an integrated passive optical network monitoring system for fault detection and localization. Fault detection technology is based on the recognition of reflection spectrum generated by each single fiber Bragg grating, which can support large-capacity user fiber fault monitoring. Fault localization method uses two different total received powers measured by an optical power meter to solve the established equation, and it shows a good accuracy compared with the OTDR measurement results. Fault detection and localization are carried out separately but share the same transmitter module. The introduction of the additional module ensures that the troubleshooting does not affect other normal user data communication. We also investigate the dynamic range requirements of the fault detection technology and the measurement error of the fault localization method. The calculation results show the required dynamic range for the recognition device can be maintained within a small range and the use of high-accuracy optical power meter can reduce the measurement error. The proposed monitoring system can simultaneously provide a large-capacity fault detection technology and high-accuracy fault localization method in a cost-sensitive passive optical network market.

Quadrupole Antenna and Diagnostic Complex for Ion Cyclotron Plasma Heating and Current Drive at the L-2M Stellarator

—A quadrupole antenna has been designed and produced at the L-2M stellarator for experiments on ion cyclotron plasma heating and current drive. Using a power meter of the incident and reflected waves, the first measurements of the radiation resistance of the antenna have been performed in the ohmic heating regime. The radiation resistance of the antenna has been measured as a function of the mean plasma density. It is shown that the fraction of absorbed power ensured by the coaxial modes is 25%. The created quadrupole antenna can also be used for current drive. The proposed method is based on the conversion of fast magnetosonic waves to slow magnetosonic waves with their subsequent absorption by plasma electrons, which is accompanied by current drive processes.

Application of power metering automation in online loss management

The electric power industry is a very important fundamental industry in China’s social and economic development and innovation project, which has an extremely crucial influence on the development and construction of traditional industries, construction industries and information technology fields. In order to accelerate the process of urbanization and construction of a well-off society, power-related enterprises should carry out scientific and standardized supervision and management on generation, transportation, transformation, configuration and the use of electricity, the aim is to ensure that they can comply with rule of the national standards and the needs of social development.

Light intensity correction for quartz-enhanced photoacoustic spectroscopy using photothermal baseline

A convenient method of light intensity correction for quartz-enhanced photoacoustic spectroscopy (QEPAS) using photothermal baseline is demonstrated. The laser beam passes through the prongs of the quartz tuning fork (QTF) and then focused on the root of the prongs. First harmonic (1f) analysis is utilized to process the simultaneously induced photoacoustic and photothermal signals. The optical path length for photothermal spectroscopy is minimized to millimeter level, yielding negligible gas absorption. The demodulated 1f signal can be regarded as the superposition of the photoacoustic signal and the non-absorption photothermal baseline. A good linear relationship (R2 = 0.999) is observed between amplitude of photothermal baseline and light intensity. QEPAS signal normalized by photothermal baseline shows a good immunity to light intensity variation. An excellent linear response between normalized QEPAS signal and gas concentration is achieved. According to the Allan deviation analysis, the minimum detection limit for CH4 is 0.31 ppm at an integration time of 1,200 s. With this strategy, the precise gas concentration and accurate light intensity of a QEPAS system can be simultaneously obtained with only a single QTF. Compared with the light intensity correction using a photodetector or a power meter, this method entails a low cost and small footprint. It is promising to mitigate the influence from light intensity drift in long-term field measurement of QEPAS systems.

Competitive Racing in Virtual Cycling—Is It Possible, Realistic, and Fair?

Competitive racing through virtual cycling has established itself as an entirely new discipline within cycling. This study explores what equipment racers use and examines important power metrics for racing. Data were collected from three different races from the current ranking of the most highly regulated and professionally organized race series on the virtual cycling platform Zwift. Power output data from 116 race participants, over five power durations (5 s–20 min), and two separate power measuring sources were collected and analyzed using the Bland–Altman method. The findings indicate that the physiological efforts of these races are comparable to those found in traditional competitive cycling. Furthermore, findings also support that the equipment typically used produces similar power outputs with good agreement between different power meters for most measurement points. Finally, the implications of these results for the status of virtual racing are discussed.

Measurement Error Prediction of Power Metering Equipment Using Improved Local Outlier Factor and Kernel Support Vector Regression

The measurement error evaluation of power metering equipment (PME) is significant for the instrument design and accurate metering of electric energy, especially under extreme environmental stresses. However, actual measurement error assessment is often disturbed by the environmental noise and insufficient input information. To address this problem, an improved local outlier factor (ILOF) method is first presented to detect potential outliers. And an optimized distance function and adaptive threshold constraint method based on box plot are used to improve the outlier detection performance of ILOF. Next, an error prediction method, namely kernel support vector regression (KSVR), is presented to fuse measurement error and multiple extreme environmental stresses by using the proposed kernel approach. Integrating the ILOF and KSVR, examples from the extreme environmental region demonstrate that the proposed evaluation framework has a higher assessment performance. Compared with several state-of-art prediction methods, our framework has profound outlier identification and error prediction performance under small sample conditions.

FastCache: A write-optimized edge storage system via concurrent merging cache for IoT applications

To tackle the microwrite issue in Internet-of-Things (IoT) applications, i.e., massive small size and concurrent random write requests, a straightforward approach is to establish cache mechanisms at the edge to reconstruct writing operations and flush data efficiently. In spite of recent research efforts on cache mechanisms, existing approaches still face unsolvable problems like frequent competition on cache blocks, massive fragments caused by merging, and cache pollution due to cache updating, especially in IoT scenarios with highly concurrent microwrites. To address these problems, we design and implement FastCache, a write-optimized edge storage system via concurrent microwrites merging. By leveraging an optimistic lock scheme, we implement a two-level cache structure that dispatches the concurrent write threads efficiently and significantly mitigates the cache block competition problem. Further, we propose a flexible merging scheme to avoid excessive fragments and the corresponding cache updating policy based on a throughput-aware threshold and a Poisson Distribution Sampling scheme. Extensive experiments on both synthetic workloads and a real-world trace from 20 million power meters with highly concurrent microwrites demonstrate that FastCache outperforms the state-of-the-art approaches, e.g., up to 14.6× and 5× improvement in terms of IOPS on synthetic and real-world workloads, respectively.