- 标题
- 摘要
- 关键词
- 实验方案
- 产品
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Effects of waveform parameters on the breakdown characteristics of OIP subjected to impulse voltages and evaluation method for waveform equivalence
摘要： The impulse voltage wave invading a transformer is not the double exponential impulse wave (DEIW) specified by the IEC but a non-standard waveform with oscillation attenuation characteristics, and this fact leads to doubts about the scientificity and optimality of insulation coordination. A key solution for this issue is the establishment of an equivalent relationship between the measured non-standard impulse voltage wave and the DEIW. In this study, a test platform of multiparameter impulse voltage was set up. Then, the authors obtained the 50% breakdown voltage (U50%) of the oil-impregnated paper (OIP) for transformer under the bipolar oscillatory attenuated impulse wave (BOAIW) and the DEIW with different waveform parameters. The effects of waveform parameters on the breakdown characteristics of the OIP were finally revealed. On the basis of experimental data and several mathematical methods, the authors established the U50% prediction mathematical models for the OIP under the BOAIW and DEIW. Based on the prediction models and the microfluctuation characteristics of measured overvoltage's waveform parameters, the authors proposed a method for evaluating the waveform equivalence. The characteristics of voltage amplitude and change rate were regarded as the two key factors for the waveform equivalence of this method.
关键词： evaluation method,breakdown characteristics,waveform equivalence,impulse voltage,oil-impregnated paper
更新于2025-09-23 15:21:21
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Thermal Imaging of Flame in Air-assisted Atomizer for Burner System
摘要： Infrared thermography was used as a part of non-intrusion technique on the flame temperature analysis. This paper demonstrates the technique to generate the thermal images of flame from the air-assisted atomizer. The multi-circular jet plate acts as a turbulence generator to improve the fuel and air mixing in the atomizer. Three types of multi-circular jet plate geometry were analysed at different equivalence ratio. Thermal infrared imaging using FLIR thermal camera were used to obtain the flame temperature. Multi-circular jet 1 shows the highest flame temperature obtained compared to other plates. It can be concluded that the geometry of the plate influences the combustion, hence affects the flame temperature profile from the air-assisted atomizer.
关键词： flame temperature,multi-circular jet plate,Infrared thermography,air-assisted atomizer,equivalence ratio
更新于2025-09-23 15:19:57
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[IEEE 2019 Chinese Control And Decision Conference (CCDC) - Nanchang, China (2019.6.3-2019.6.5)] 2019 Chinese Control And Decision Conference (CCDC) - Design of Photovoltaic Charging Pile for Electric Bicycle Based on New Inverter
摘要： In view of the shortcomings of electric bicycle charging infrastructure and the single use of photovoltaic new energy generation, this paper proposes a design scheme of electric bicycle photovoltaic charging pile based on new inverter, and designs a new model that can be applied to photovoltaic charging piles. Using a simplified virtual space vector pulse width modulation inverter control scheme suitable for photovoltaic charging piles not only effectively solves the problem of midpoint voltage imbalance, but also successfully simplifies the implementation of virtual space vector modulation (NTV2) to save the main control resources.
关键词： double wave pulse width modulation,photovoltaic charging pile,virtual space vector modulation,new inverter,equivalence
更新于2025-09-16 10:30:52
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Simultaneous measurements of fuel concentration and temperature in gas jets by laser induced breakdown spectroscopy
摘要： Laser induced breakdown spectroscopy (LIBS) enables quantitative measurements of the equivalence ratio in flames, spray and gas jets. Although there are always considerable temperature differences between the calibrations and the LIBS measurements in flames and fuel jets, the temperature effects on LIBS were rarely mentioned and not corrected in the previous LIBS measurements. In this study, a novel method to simultaneously measure the equivalence ratio and the gas temperature by LIBS in a single laser shot is proposed. This method can correct the temperature effects based on the linear correlation between the peak intensity ratio (PIR) of atomic lines and the gas temperature. The PIR of H656/N746 and the full width at half maximum (FWHM) of H656 are employed to establish calibration curves with the equivalence ratio and the gas temperature, respectively, and both of calibrations show high coefficients of determination (R2). Then, the measurement accuracy and precision of the proposed method are discussed in detail. The total uncertainties in measurements of equivalence ratio and gas temperature are estimated by 5.6% and 5.8%, respectively. Finally, the simultaneous measurements of equivalence ratios and gas temperatures in methane jets at different positions and at different injection pressures are conducted. The comparison of equivalence ratios before and after correction of the temperature effects indicates that the accuracy of the fuel concentration measurements by LIBS would be remarkably degraded if the temperature variations were neglected.
关键词： Measurement uncertainties,Laser-induced breakdown spectroscopy (LIBS),Equivalence ratio,Gas temperature,Full width at the half maximum (FWHM)
更新于2025-09-12 10:27:22
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Satellite Laser-Ranging as a Probe of Fundamental Physics
摘要： Satellite laser-ranging is successfully used in space geodesy, geodynamics and earth sciences; and to test fundamental physics and specific features of General Relativity. We present a confirmation to approximately one part in a billion of the fundamental weak equivalence principle (“uniqueness of free fall”) in the Earth’s gravitational field, obtained with three laser-ranged satellites, at previously untested range and with previously untested materials. the weak equivalence principle is at the foundation of General Relativity and of most gravitational theories.
关键词： geodynamics,weak equivalence principle,space geodesy,Satellite laser-ranging,General Relativity
更新于2025-09-11 14:15:04
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[IEEE 2018 International Conference on Electromagnetics in Advanced Applications (ICEAA) - Cartagena des Indias, Colombia (2018.9.10-2018.9.14)] 2018 International Conference on Electromagnetics in Advanced Applications (ICEAA) - Equivalence Principle Algorithm for Potential Integral Equations
摘要： We present a new frequency-domain implementation of the equivalence principle algorithm (EPA) using the recently developed potential integral equations (PIEs) as inner formulations. The set of equivalent sources is updated by including all components of electric and magnetic fields, as well as potentials required for PIEs. The developed implementation is stable when applied to challenging problems involving extremely dense discretizations with respect to wavelength, while it is efficient at the same time thanks to the improved iterative solutions using EPA. The accuracy of the implementation is shown for the first time on canonical problems.
关键词： equivalence principle algorithm,dense discretizations,frequency-domain,potential integral equations,canonical problems
更新于2025-09-10 09:29:36
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Negative refraction, light pressure and attraction, equation <i>E</i> ?=? <i>mc</i> <sup>2</sup> and wave-particle dualism
摘要： This paper is aimed to illustrate the relation of concepts, such as negative refraction, light pressure and attraction, mass–energy equivalence and wave-particle dualism. At ?rst glance, those physics concepts have nothing in common. However, on closer examination it appears that they are closely linked, although this relationship was clearly shown only relatively recently, when a scienti?c development introduced the concept of negative refraction.
关键词： Light pressure and attraction,Negative Refraction,Mass–energy equivalence,Wave-particle dualism
更新于2025-09-10 09:29:36
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Effects of gravity on continuous-variable quantum key distribution
摘要： The domain of quantum technologies has been recently broadened to satellites orbiting the Earth. Long distance communication protocols cannot ignore the presence of the gravitational field and the effects on the quantum states. Here, we provide a general method to investigate how noninertial motion affects the performance of various quantum key distribution protocols for continuous-variable states of localized wave packets. Taking advantage of the equivalence principle, our results can be thought of as due to the gravitational field. We show that the consequences of gravity strongly depend on the configuration and the cryptographic scheme used.
关键词： noninertial motion,equivalence principle,quantum key distribution,continuous-variable states,gravitational field
更新于2025-09-04 15:30:14