Power Calculation Model Research Articles

Research on transient temperature rise characteristics of composite cylindrical roller bearings

Composite roller bearings have received extensive attention from bearing design engineers because of their good contact and running performance. According to the contact mechanical characteristics of composite cylindrical roller, a bearing heat generation power calculation model is established. Then, using the local heat source analysis method, and considering the heat conduction mode, the transient temperature solution model of bearings is established. The influence of filling ratio, radial force, angular velocity and roller numbers on the heat generation power and steady-state temperature of the bearing components is calculated and analyzed. The calculated results are in good agreement with the experimental results, which verifies the correctness of the model. The model can accurately predict the temperature distribution of bearings, providing new ideas and methods for temperature rise analysis, and laying the foundation for temperature analysis of bearings.

Calculation method and mathematical model of projectile echo power of active laser detection target

AbstractTo meet the requirements for parameter testing within the projectile test system, a computational model for calculating the echo power of the projectile passing through the detection screen based on the principle of active laser detection target is established in this paper. On the basis of the fundamental formula of echo energy in laser detection, and by combining the energy distribution function of the detection screen, the light scattering cross‐section formula specific to the projectile, and the illuminated area formula when the projectile intersects the detection screen, the formula for calculating the echo power of projectile is derived and analyzed. Furthermore, taking into account the parameters of the laser detection target, a computational model is constructed to calculate the voltage amplitude associated with the echo power of the projectile. Combining the atmospheric transmission optical characteristics, distance variations, and changes in the projectile's reflection attitude in the test environment, we conducted a simulation analysis to assess the accuracy of the established calculation model. Additionally, experimental analysis of the echo power calculation model was performed. In both simulation and experimental analyses, the trends in the impact of atmospheric transmission optical characteristics, distance conditions, and changes in projectile attitude upon the calculation of projectile echo power were consistent. Moreover, the width of the projectile echo waveform obtained in experiments was equal to the calculated projectile duration time. These research findings can serve as a reference basis for the development of theories in laser detection target.

Integrated modeling and coupling characteristics analysis of helicopter/engine/infrared suppressor

Abstract In order to explore the influence of the infrared stealth technology on the performance of the integrated helicopter/engine system, an integrated modeling method of helicopter/engine/infrared suppressor is proposed. Firstly, based on the power calculation model of the helicopter, combined with the high-precision turboshaft engine component-level model, an integrated simulation platform is built, which takes into account the nonlinear characteristics. Then, the aerodynamic characteristics of infrared suppressors under different engine operation states are studied by CFD numerical computation method, and the infrared radiation characteristics are obtained through combining the positive and negative ray tracing method and narrow band model method. Ultimately, the utilization of the power turbine outlet stagnation pressure is employed as the pivotal interface linking the turboshaft engine and the infrared suppressor in order to formulate an integrated model encompassing the helicopter, engine, and infrared suppressor subsystems. The simulation results demonstrate that compared with the conventional exhaust system, the application of the infrared suppressor greatly enhances the stealth performance of the helicopter, but also results in the unexpected decrease in engine output power. Moreover, the specific fuel consumption of the turboshaft engine increase and the compressor surge margin decreases in case of the consistent flight condition.

Simulation study on the influence of thickness and relative foaming height of refining slag on electrothermal characteristics in ladle furnace

Electrothermal characteristics play a crucial role in ladle furnaces that utilize electric energy for heating purposes. In this paper, a three-dimensional electrothermal power calculation model of ladle furnace is established based on electromagnetism, the influence of thickness and relative foaming height of refining slag on electrothermal characteristics was studied, and the electrical conductivity of refining slag was measured using AC impedance method. The study revealed that the electrical conductivity of the primary slag and final slag is 101 S/m and 92 S/m respectively at 1575 °C. During energization and heating, the current is mainly conducted through electrodes, arcs, and molten steel, the three-phase current is finally connected in the molten steel near the interface between slag and molten steel, and a small amount of current is connected through refining slag. The electrothermal power of the arc accounts for the largest proportion of the total electrothermal power, reaching 96.8%, while the electrothermal power of the molten steel is the smallest. When the thickness of the refining slag increases from 0 mm to 150 mm, the electrothermal power of the refining slag increases from 0 kW to 759.7 kW, while the electrothermal power of the molten steel and arc decrease from 60.9 kW, 18783.5 kW to 44.3 kW and 17440.2 kW, respectively. When the relative foaming height increases from 0 to 150%, the electrothermal power of refining slag increases from 412.4 kW to 449.6 kW, and the electrothermal power of molten steel and arc decreases from 54.1 kW, 18172.1 kW to 51.1 kW and 17194.3 kW, respectively.

Investigations on System Integration Method and Optimum Design Method of Electro-Mechanical Actuator System

With technological advances and industrial upgrading, high-performance equipment has put higher demands on the performance of electro-mechanical actuators. With a view to making electro-mechanical actuators more reliable and integrated, firstly, an integrated electro-mechanical actuator module (IEMM) with multiple structural forms was proposed in this paper, and a comparative analysis was performed on the characteristics of different transmission schemes. Then, the feasibility of manufacturing the IEMM’s main bearing components using Carbon Fiber Reinforced Polymer (CFRP) with higher specific stiffness, specific modulus and specific strength was demonstrated by finite element simulation (FEA) software, in a bid to further reduce the weight of the IEMM. Next, a parameter estimation model, a heating power calculation model, and a thermal resistance calculation model were built, so that there is no need to rebuild the whole system model under different demand indexes. On this basis, a multi-objective optimization design model was built with light weight, low power loss, and high level of integration as optimization aims to achieve better comprehensive performance in the early design phase of the IEMM system. However, IEMM’s higher level of integration and its shell made of CFRP with a thermal conductivity of less than 5 W/m°C posed a challenge to the heat dissipation of the motor stator. Therefore, a thermal network model needs to be created in AMESim to evaluate the temperature of IEMM’s parts and components under different working conditions. Finally, the process of IEMM performance optimization design was described and improved, and performance optimization design was conducted by taking one of IEMM’s transmission schemes as an example.

Internet of Things in Sport Training: Application of a Rowing Propulsion Monitoring System

The application of electronics, communication, and telemetry technologies in the field of sport training is a major trend today, specially with the explosion of the Internet of Things (IoT) paradigm. In particular, the rowing sport is one of the disciplines that could benefit from efficient, easy to integrate, and low cost IoT technologies to help analyzing and optimizing the performance of the rowers. However, traditionally monitoring tools in rowing are expensive and very limited. In this work, a rowing propulsion monitoring system for onboard analysis of rower’s key parameters is proposed, based on the development of a low-cost IoT device that combines sensing, global positioning, wireless communication, and data fusion for runtime information processing and monitoring on the boat. A power calculation model during the stroke is also proposed in order to estimate the energetic efficiency of the strokes in relation with the boat velocity. An acceleration sensor on the oar is used to decompose the movement; a torsion sensor to calculate the rower’s strength and energetic values; and navigation data for speed and distance values of the boat. A comprehensive comparative experimentation in a real rowing training scenario is performed, applying the proposed system and considering various rowers. The results show that the device provides a good vision in time of the movement and also very valuable technical information that can be used by rowers and trainers to define specific optimization profiles and improvement targets.

Solar Array Power Prediction for Near-Space Vehicles Based on a Hybrid Method

Compared with other energy sources in near-space, solar energy is more renewable, stable and accessible, which makes solar cells the main source of energy for long-endurance near-space vehicles. However, due to the limited solar cells laying area and complex flight conditions, near-space vehicles are facing tense energy supply situation during flight. Therefore, fast and accurately online power prediction of the solar array, which has important significance for power management, efficient use and reliable operation of the energy system, is the key point to solving the situation at present. In this paper, a hybrid online power prediction method combined particle filter and power calculation model is proposed. Firstly, a comprehensive solar cell array power calculation model for the near-space vehicle is established. Then, the particle filter algorithm is used to estimate optimally the important parameters in the power calculation model with the flight data, to realize the dynamic, rapid and accurate prediction of the power generation of the vehicle during flight. Finally, the data obtained from flight tests of the stratospheric aerostat and high-altitude scientific balloon are verified and compared with the other four models. The results demonstrate that the generation power prediction method proposed in this paper has higher prediction accuracy, which will be a good guiding significance for the actual flight of different types of near-space vehicles.

DESIGN PROCEDURE OF ARCHIMEDES HYDRO TURBINE

This study aims to develop a simple-practical design procedure to determine the appropriate size of the turbine's outer radius for any given internal parameters according to the available flow rate through numerical calculation. The calculation is performed using python programming language by combining the existing model of Archimedes turbine, including the power calculation model, turbine flow rate capacity, and losses modeling, into a procedural design calculation to produce the appropriate value. The design procedure could be used to obtain the required and could be able to accommodate the available water flow rate optimally for any given value of each internal parameter and available flow rate. It is obtained that a higher pitch ratio would result in smaller . Moreover, the value of 0.45 would give the smallest size of the appropriate . On the other hand, the higher turbine's inclination angle would require a greater . It is also revealed that the angle of will give the turbine optimum efficiency. In addition, it is also estimated that the Archimedes turbine would be more efficient in a higher available water flow rate. The resulting design shows a good agreement with the installed Archimedes turbine based on the surveyed data at some power plants. Therefore, the proposed design can improve Archimedes Turbine's design by providing the appropriate size of according to the available flow rate without any overflow or underfilling. The design procedure could also provide a practical tool for designing Archimedes turbine.

A pilot protection scheme for flexible HVDC transmission lines based on modulus power

Existing protection methods for Flexible HVDC transmission lines easily fail to detect the fault location fast and reliably. Concerning this problem, a modulus power based pilot protection scheme is proposed. By analyzing the dynamic switching process of sub-modules in flexible DC converter station, the expression of converter station DC voltage taking into account the influence of AC system is derived. On this basis, the modulus voltage and modulus current are calculated by phase-modulus transformation, and the modulus power calculation model containing DC components alone is built. Then, the expressions of modulus power in different fault cases are derived, and a protection criterion based on the polarity difference characteristics of modulus power is established. Finally, the RT-LAB is used to build the model of a flexible DC system for simulation verification. The results of simulation tests verify that, the proposed protection scheme can detect the fault line and fault pole fast and accurately, with easy threshold setting and low demand on communication synchronization. Besides, it is unaffected by the fault resistance and the specific boundary conditions of current-limiting reactor, etc.

Calculation model and analysis of laser echo power based on dual‐transmitter and dual‐receiver laser circumferential scanning detection mechanism

AbstractTo ensure that the laser proximity fuze can detect the ground target during the intersection between the laser detection system and the ground target, based on the dual‐transmitter dual‐receiver laser circumferential scanning detection mechanism, we established the constraint functions of scanning frequency and laser pulse frequency without missing measurement. According to the surface characteristics of the plane target, we derived the calculation models of the laser echo power and the minimum detectable echo power of the detection system to the plane target under the random intersection attitude. The calculation function of the angle between adjacent laser beams is obtained based on the minimum detectable echo power. We discussed the relation of the scanning frequency, the laser pulse frequency, the angle between adjacent laser beams and the intersection angle, focused on the influence of the intersection angle and the detection distance on the laser echo power. The simulation experiments were carried out under different laser peak powers and detection distances, the experimental results fully demonstrate that the laser echo power calculation model established in this paper is correct; the detection ability of the system is improved to a certain extent by increasing the laser peak power.

Verification of SARAX code system in the reactor core transient calculation based on the simplified EBR-II benchmark

This paper shows the verification work of SARAX code system in the reactor core transient calculation based on the simplified EBR-II Benchmark. The SARAX code system is an analysis package developed by Xi'an Jiaotong University and aims at the advanced reactor R&D. In this work, a neutron-photon coupled power calculation model and a spatial-dependent reactivity feedback model were introduced. To verify the models used in SARAX, the EBR-II SHRT-45R test was simplified to an ULOF transient with an input flowrate change curve by fitting from reference. With the neutron-photon coupled power calculation model, SARAX gave close results in both power fraction and peak power prediction to the reference results. The location of the hottest assembly from SARAX and reference are the same and the relative power deviation of the hottest assembly is 2.6%. As for transient analysis, compared with experimental results and other calculated results, SARAX presents coincident results both in trend and absolute value. The minimum value of core net reactivity during the transient agreed well with the reported results, which ranged from −0.3$ to −0.35$. The results verify the models in SARAX, which are correct and able to simulate the in-core transient with reliable accuracy.

Use of a Machine Learning Method in Predicting Refraction after Cataract Surgery.

The present study aims to describe the use of machine learning (ML) in predicting the occurrence of postoperative refraction after cataract surgery and compares the accuracy of this method to conventional intraocular lens (IOL) power calculation formulas. In total, 3331 eyes from 2010 patients were assessed. The objects were divided into training data and test data. The constants for the IOL power calculation formulas and model training for ML were optimized using training data. Then, the occurrence of postoperative refraction was predicted using conventional formulas, or ML models were calculated using the test data. We evaluated the SRK/T formula, Haigis formula, Holladay 1 formula, Hoffer Q formula, and Barrett Universal II formula (BU-II); similar to ML methods, we assessed support vector regression (SVR), random forest regression (RFR), gradient boosting regression (GBR), and neural network (NN). Among the conventional formulas, BU-II had the lowest mean and median absolute error of prediction. Therefore, we compared the accuracy of our method with that of BU-II. The absolute errors of some ML methods were lower than those of BU-II. However, no statistically significant difference was observed. Thus, the accuracy of our method was not inferior to that of BU-II.

A Transparent All-Dielectric Multifunctional Nanoantenna Emitter Compatible With Thermal Infrared and Cooling Scenarios

In modern thermal infrared applications, multi-spectral camouflage scenarios should be developed to mitigate the thermal signature of an object. In general, camouflage needs to be satisfied in two main optical ranges: visible, and infrared (IR). In the IR range, two main camera modes are deployed to detect the IR signature of an object: i) short-wave IR (SWIR) cameras that detect the solar photons reflected off a surface, ii) mid-wave IR (MWIR) and long-wave IR (LWIR) cameras that directly collect the blackbody photons emitted from a hot object. Therefore, in an ideal scheme to acquire a multi-spectral camouflage function with self-cooling capability, the object should have: i) perfect absorption in the SWIR range, ii) perfect reflection in the MWIR and LWIR ranges, iii) perfect absorption and one-way transmission in non-transmissive IR (NTIR) window (to radiatively cool itself), and iv) visible transparency (to keep background visual appearance intact and to minimize the heat build-up due to solar absorption). In this paper, an all-dielectric nanoantenna emitter design is developed to comply with all the above-mentioned requirements. The approach relies on the indium tin oxide (ITO) grating structures coated on a flexible and transparent substrate (polystyrene). The spectral behaviors of the proposed structure are obtained using both analytical and numerical approaches. The design has an absorption peak with 0.8 amplitude in the SWIR mode (for the backward and forward illuminations), while it shows average reflections ≅ 0.7 in the MWIR and LWIR ranges for the forward illumination. The peak values of transmission and absorption within the NTIR window for the forward illumination are around 0.6 and 0.9, respectively. Meanwhile, the use of lossless materials within the visible range provides visible light transmission and minimizes the heat build-up due to solar absorption. In addition, the radiated power calculation model is utilized to demonstrate the low power detection on the IR cameras.

Coordination of Electricity and Heat Dispatch Strategy Combining Carbon Trading and Peak Shaving Compensation Mechanism

Integrated power generation group’s participation in the carbon trading market and peaking auxiliary service market is one of the effective ways to promote low carbon power development and wind power consumption. Aiming at the serious problem of wind abandonment during the low temperature period of winter heating period in Northeast China, a multi-market mechanism is proposed. The carbon trading is analysed. Firstly, and the regional peak demand optimization model based on multi-scenario stochastic programming and the maximum wind power acceptance power calculation model of regional power grid is constructed to calculate the peak shaving demand and existing peak shaving in each period of the regional power grid. Maximum wind power acceptance under resources; Based on the coordination of carbon quotas among power generation groups and the subsection compensation mechanism of compensated peak shaving costs, and aiming at the minimum sum of total coal consumption costs, wind abandonment penalties and compensation costs, integrated dispatching model considering carbon trading and peak shaving compensation is established. Finally, an example is given to verify the rationality and effectiveness of the proposed strategy.

Road surface condition detection utilizing resonance frequency and optical technologies

With the booming development of road network and intelligent transportation systems, road surface condition information becomes more and more valuable in traffic accident prevention and route optimization. Although some existing embedded detectors have been providing road condition data in some regions, they are not functional enough in either complex condition recognition or film thickness measurement. This paper introduces a dual-sensor based road condition detector for six surface conditions with ice and water film measurement capability. The reflection type optical sensor and the piezoelectric sensor utilizing resonance technology are integrated in the detector. The finite element analysis was carried out to study the amplitude frequency response characteristics of the piezoelectric sensor and the optical power calculation model based on Fresnel Reflection was built to evaluate the output voltage of the optical sensor in different conditions. Several experiments were done to calibrate the detector and validate its performance. The results indicated that all of the 353 validation data points were correctly sorted and the measurement upper limit of the ice and water film was above 5 mm with accuracy better than 0.5 mm.

A Method of Calculating the Daily Output Power Reduction of PV Modules Due to Dust Deposition on Its Surface

Compared with the cleaned photovoltaic (PV) modules, the output power of the dusty PV modules decreases. In this paper, the factors influencing dust concentration on the PV module glazing surface are studied and discussed. Based on the optical analysis, a method of calculating the output power reduction of PV modules due to dust deposition on its surface is proposed. According to changes of daily PM10 and rainfall, the output power reduction of PV modules can be calculated, which lays a foundation for the formulation of the cleaning strategy. In addition, experiments of dust deposition on the surface of PV modules are designed in Changzhou and Yantai, China, to verify the theoretical output power calculation model. According to the result of experiment and calculation, not only can this method accurately calculate the daily power loss caused by the dust deposition on PV modules surface, but also it can make up for the large fluctuation of outdoor experiments (measurement of the output power reduction of PV modules due to dust deposition) under the changeable weather of radiation.

An optimal dispatching strategy for V2G aggregator participating in supplementary frequency regulation considering EV driving demand and aggregator’s benefits

With the development of Vehicle-to-Grid (V2G) technology and increasing number of electric vehicles (EVs) integrating in power grid, supplementary frequency regulation service provided by V2G aggregator has been seen as the most promising grid ancillary service provided by the integrated EVs. In this paper, an optimal dispatching strategy of V2G aggregator is proposed to satisfy the driving demand of EV owners and maximize the economic benefits of aggregator simultaneously when it participates in supplementary frequency regulation. A judgment module is designed to determine EVs in aggregator whether participating in frequency regulation according to EV battery SOC for EVs’ driving demand, which is calculated by EVs’ daily driving distance. An optimal regulation power calculation model is built to optimize profits of aggregator and tracking performance of frequency load control signal from grid operator. A fair regulation power allocation module is designed to avoid over-discharging of EVs in aggregator. Finally, the proposed strategy is implemented in the simulation experiments to demonstrate its effectiveness.

Design and verification of engine power calculation model using the data of a digital bus built into an agricultural tractor

Engine power is a fundamental parameter for determining the utilization of an agricultural tractor. A wrong combination of a tractor and agricultural machinery leads to non-efficient loading of the engine, which causes not only a waste of energy stored in the fuel but also increased financial cost of production. The presented paper focuses on the possibility to calculate engine power from the data, which are available on the digital bus – CAN-BUS. Choosing the appropriate parameters together with the proposed model can help represent the instantaneous power needs. The messages, which provide the basic information about the load, are as follows: engine load, instantaneous torque, instantaneous fuel consumption, engine speed and a set of correction channels. These channels bring the cluster of temperatures and pressures of engine fluids, mainly of the fuel and engine lubricating oil. Without prior determination of the regression function, the data, especially in low load, are very different from the actual torque generated by the engine and measured by a dynamometer. The model represents a function of surface features with a very high index of determination. The model was verified by measuring the power of the engine on a dynamometer. Validation of the model in practice was carried out in the field. The tractor was connected with combined cultivator. The experiment results show a very high statistical match of the results obtained in the laboratory and in field measurements.

Study of the road traffic noise prediction method applicable to low-noise road surfaces

In this study, the new road traffic noise prediction method applicable to Japanese and Dutch various road surfaces was developed. Firstly, the A-weighted sound power levels of road vehicles were measured for actual roads in the Netherlands paved with various surfaces. With regard to the levels on dense asphalt concrete, the differences between Dutch and Japanese data were not significant, therefore it was found that the common sound power calculation model can be used in both Japan and the Netherlands. On the other hand, the levels for low-noise road surfaces in the Netherlands were 1 to 7 dB lower than those for dense asphalt concrete, therefore the different sound power calculation models were required to be constructed for such surfaces. Secondly, based on the above results, a sound power calculation model applicable to each road surface was developed. By integrating the model with the dynamic traffic flow calculation model, the new road traffic noise prediction method was constructed. Using the method, the road traffic noise in 32 urban areas including low-noise road surfaces in Japan and the Netherlands was calculated. As a result, the calculated levels correspond well with the measured levels (the differences between them were 1.3 dB on average).

Power calculation for group fMRI studies accounting for arbitrary design and temporal autocorrelation

When planning most scientific studies, one of the first steps is to carry out a power analysis to define a design and sample size that will result in a well-powered study. There are limited resources for calculating power for group fMRI studies due to the complexity of the model. Previous approaches for group fMRI power calculation simplify the study design and/or the variance structure in order to make the calculation possible. These approaches limit the designs that can be studied and may result in inaccurate power calculations. We introduce a flexible power calculation model that makes fewer simplifying assumptions, leading to a more accurate power analysis that can be used on a wide variety of study designs. Our power calculation model can be used to obtain region of interest (ROI) summaries of the mean parameters and variance parameters, which can be use to increase understanding of the data as well as calculate power for a future study. Our example illustrates that minimizing cost to achieve 80% power is not as simple as finding the smallest sample size capable of achieving 80% power, since smaller sample sizes require each subject to be scanned longer.