bluuebunny/crossref_metadata_2025_split huggingface dataset:
An Efficient Short-Term Electricity Forecasting Approach Based on EEMD-LSTM Model with Feature Factors
Authors: Tian Y J , Luo J R , Wen M , Li J G 
Published: March 2021

AbstractThe forecasting of electricity consumption data plays an important role in the operation, planning, and security of the power grid. However, electricity data is affected by multiple factors and large fluctuations, which makes it difficult to accurately forecast. Traditionally, ARIMA and SVM are widely used for electricity forecasting based on historical consumption data. However, for non-stationary multi-feature data, traditional schemes cannot achieve deep feature mining of them, and the forecast results are inaccurate. To address this problem, this paper proposes an efficient short-term electricity forecasting approach based on EEMD-LSTM model. Firstly, we perform Savitzky-golay (SG) smoothing on the original data, and then introduce feature factors to the feature analysis. In particular, the proposed approach can reduce the random noise in data, as well as reduce the impact of data fluctuations, and effectively learn the long-term characteristics of the data. The simulation results show that, compared with ARIMA, LSTM, EMD-SVM, EMD-LSTM, the proposed approach can achieve better accuracy in the electricity forecasting.
A Design of Three-level Inverter Based on PCI Control
Authors: Qu L M , Wang C , Zhang H D , Lin Y 
Published: March 2021

Abstract
To solve the problem that the PI-controlled three-level inverter can’t achieve zero steady-state error on AC, a closed-loop control scheme using the PCI controller is proposed. The voltage and current double closed-loop control scheme is adopted. The circuit of diode-clamped three-level inverter is selected as the controlled object. And the PCI controller is designed. The zero steady-state error of three-level inverter based on the PCI control is analyzed in detail. Finally, the closed-loop control system of three-level inverter is simulated on the MATLAB/Simulink platform. The results show that the PCI control has good dynamic response ability and can accurately track various sudden loads. And then the correctness of theoretical analysis is verified.
Research on High Power Ultrasonic Power Supply Based on Cascaded 9 Level Technology
Authors: Zhou C H , Zhang C Z , Zhang W Y , Tian Y , Wang C R , Shu Y H 
Published: March 2021

Abstract
In view of the low output power and high power density of ultrasonic power supply, a high power ultrasonic power supply based on 9-level inverter technology is proposed. The inverter of the power supply consists of two H-bridge units cascaded to form a 9-level converter, which outputs the 9-level voltage waveform, which can significantly improve the output power of the ultrasonic power supply, reduce the inductance of the matching network, and reduce the power density of the ultrasonic wave. The phase difference method based on PI control is used to track the resonance frequency. By analyzing the system structure, working principle and control strategy of the ultrasonic power supply, modeling and simulation were conducted on Matlab/Simulink to verify the feasibility and effectiveness of the scheme.
Study of Thermal Supply Mode of Floating Nuclear Power Plant in Offshore Oil and Gas Fields
Authors: Zou S F , Gong D X , Song J , Zhao J , Zhang X H 
Published: March 2021

Abstract
The floating nuclear power plant (FNPP) is a solution to the thermal supply in offshore oil and gas fields, including the applications in thermal recovery and flow assurance. The output power of marine reactors under development in China matches the thermal demand of offshore oil fields. In order to analyse the thermal supply mode, the following aspects are investigated: the application scenarios, the thermal loss of the thermal supply pipeline, and the selection of platform type. Then, a case study is presented to illustrate the applicability of FNPP in the Bohai Sea for the enhancement of oil recovery. The case shows that the current solution works well with the offshore marginal oil field. The future solution is also discussed as to further improve the economy of FNPP.
Experimental Study on the Effect of Phase Change Material Melting Point on TG/PCM Thermal Control Properties
Authors: Xiao L X , He Y T , Wang J Q 
Published: March 2021

Abstract
Three composite phase change materials (PCM) with peak melting points of 42°C, 50°C and 58°C were prepared using different mass fractions of stearic acid (SA) and lauric acid (LA). A thermal control model structure of thermoelectric generation/PCM (TG/PCM) was designed using PCM, and analyzed for its internal thermal conversion, transmission and storage mechanisms. In addition, TG/PCM experimental prototypes with PCM melting points at 42°C, 50°C and 58°C were designed and tested for their temperature control properties and output power. The results showed that under PCM melting points of 42°C, 50°C and 58°C, temperature difference between the cold and hot end of the TG/PCM prototype thermoelectric battery was maintained above 8°C for 70 minutes, 45 minutes and 27 minutes, respectively. The total energy of system output power above 6mW was 73.9J, 52.4J and 18.9J.
Design and Implementation of an Innovative Series Power Supplies for Solar Unmanned Aerial Vehicles
Authors: Jin Y , Wang X , Ma D , Jin S N 
Published: March 2021

Abstract
Conventional unmanned aerial vehicles power systems only have one MPPT controller to operate. And MPPT controller will be influenced by loss of solar arrays and multiple maximum power points. In this paper, an innovative topology of UAV power system is proposed as well as generating a related MPPT control strategy to keep output voltage increase slowly. Hardware circuit design is presented based on selection of power diode, input filter capacitance, output filter capacitance and parallel diode. A prototype of 1.2kW power supplies is implemented to verify the proposed topology and MPPT control strategies.
Study on a New Method of Determining Boiler Soot-blowing Steam Flow Rate
Authors: Chen H Y , Xue Z H , He X X , Pei D S , Zhangand P F , Sun J F 
Published: March 2021

Abstract
In this paper, a new method of determining boiler soot-blowing steam flow rate was proposed. By this method, three tests of unaccounted-for leakage rate of the unit thermal system should be conducted without soot blowing, and the unaccounted-for leakage ratio difference between arbitrary two tests should be within 0.10%. The average value of three unaccounted-for leakage flow rate test results was used as the final result of unit unaccounted-for leakage flow to determine the flow rate of soot-blowing steam. During the test period of power output and heat rate, the calculation of soot blowing steam flow rate took account of the result of unaccounted-for leakage tests and the water level change of condenser hot well, deaerator and boiler drum.
Investigation of Radiative Properties of a Multi-particle Cloud with Non-uniform Particle Size Distribution
Authors: Cheng Z M , Wang F Q , Gong D Y , Liang H X , Shuai Y , Li G Q 
Published: March 2021

Abstract
Particle systems involve numerous fields such as combustion, oceanography, photocatalysis, and atmospheric science, among others. In fact, most of these systems were in the form of multi-particle systems composed of different types of particles. In most previous studies, the influence of the type of element on radiative characteristic parameters was not considered, or the effective medium theory was adopted, which led to large calculation errors. In this paper, the differential-integration algorithm developed based on the Mie theory was used to calculate the radiative characteristics (extinction coefficient, absorption coefficient, scattering phase function, asymmetry factor) of a multi-particle system with non-uniform size distribution, and the Monte Carlo ray-tracing (MCRT) method was used to solve the radiative transfer equation (RTE). SiO2 particles and polystyrene particles were investigated and subsequently divided into two categories: submicron particles (χ
>1) and nano particles (χ
>1) according to the size parameter. The radiative characteristics and spectral transmittance of particles with different volume fraction ratios and different particle sizes in the multi-particle system were also investigated. The results of the proposed method were compared to those of experimental tests to verify the accuracy of the algorithm. The maximum relative transmittance error decreased from 30.1% to 0.77%, and the average error decreased from 18.78% to 0.67%.
Analysis and Design of Three-Level Full-Bridge LLC Resonant Converter Based on Pulse Frequency Modulation
Authors: Liu J Z , Zhao Y , Hu P , Chen T T 
Published: March 2021

Abstract
Aiming at the problem of serious switching loss in high-power and high-voltage occasions, the traditional LLC resonant network is difficult to adapt, the DC gain is difficult to obtain intuitively, and the voltage stress on the switch is too high, resulting in large switching losses and difficult selection of the switch. This paper uses a three-level full-bridge LLC resonant converter topology, the First Harmonic Approximation (FHA) is used to analyze the LLC resonant converter gain characteristics, and the parameter design ideas are given. A simulation experiment of a three-level full-bridge LLC resonant converter based on frequency modulation control is presented. The simulation results show that each primary side switch transistor can achieve zero voltage switching (ZVS), the secondary side diode realizes zero current switching (ZCS), and can obtain higher working efficiency, which verifies the feasibility of the design.
Numerical Investigation of the Clocking Effect on the Centrifugal Pump as Turbine
Authors: Jiang W , Liu Z L , Wang Y C , Yang J G , Hou G Y 
Published: March 2021

Abstract
The clocking effect is widely recognized to have an important impact on the function of rotating machinery. The effect of the clocking position on the flow field and the hydraulic performance in a pump as turbine (PAT)with vane diffusers has been investigated and analyzed numerically. The results show the hydraulic performance of the PAT decreasing gradually as the diffuser blade near the tongue. Under optimal operating conditions, the maximum difference in efficiency for different guide vane positions is 2.2%. When the position of the tongue is equidistant from the two diffuser blades, the energy loss of the volute and the diffuser is minimized. And the flow field results prove that the timing position affects the flow field in the volute and diffuser to a certain extent, but has little effect on the impeller. In addition, this may provide ideas for the installation of PAT with guide vanes, and the diaphragm should be as far away as possible from the two adjacent diffuser blades.
Research on Ultrasonic Power Supply Based on Cascade Buck Technology
Authors: Zhang W Y , Zhang C Z , Zhou C H , Zhu Y J , Shu Y H 
Published: March 2021

Abstract
In view of the large voltage harmonics and low power density of the low-power ultrasonic power supply, a low-power ultrasonic power supply based on the cascade buck technology is proposed. The converter of the power supply is composed of two buck units in cascade, and the output of the unit is forward Sinusoidal half-wave DC voltage waveform, and then commutated by the full-bridge inverter every half cycle to output sine wave AC voltage waveform, can significantly reduce the voltage harmonics of the ultrasonic power supply, reduce the inductance of the matching network, and improve the ultrasonic wave Power density. Through the combination of voltage and current phase detection and PI regulator, the tracking resonance frequency is controlled. By analyzing the system structure, working principle and control strategy of the ultrasonic power supply, modeling and simulation are carried out on Matlab / Simulink, and the feasibility and effectiveness of the scheme are verified.
Defect Text Mining Technique and Application in Power Grid Based on the modified Semantic Framework
Authors: Yang T M , Wang Y H , Han Z T , Liang Y , Gao J , Ji X 
Published: March 2021

Abstract
There are mass data that contain important defect texts in the power grid enterprise, and they contain important reliability information. And the efficiency is very low to mine the exact information about the texts especially when the texts are in Chinese. Thus, the defect text mining technique based on the modified semantic framework is proposed. All texts are translated into English and use the text mining model based on the modified semantic framework, the defect texts are divided into a fixed pattern and the digital information can be extracted accurately. Take the transformer as an example, the first step is to establish the ontology dictionary and to separate the sentence and extract the texts’ features. Then, the modified power semantic framework and the semantic slots are defined, and the slots filling method and the semantic framework construction process are discussed, which can automatically perfect the ontology dictionary by merging the word series. Finally, the researches of defect text mining results of statistical reliability are studied, and the results show that the proposed model and method is feasible and effective when applied to automatic classification and statistics of grid defect.
Investigation of Complex Permittivity/Conductivity Distribution by Electrical Tomography
Authors: Wang R C , Gao Y , Wang G J , Li Q P , Wang Q , Wang H G 
Published: March 2021

Abstract
The electrical tomography technology is a multi-phase flow detection technology. This technology has the advantages of non-radiation, non-invasive and visualization, can be widely used in traditional energy field and new energy field. The permittivity and conductivity, as the basic electrical parameters of material, are closely related to the distribution of material in multiphase flow. However, in the actual multiphase flow, due to the non-uniform distribution of permittivity and conductivity in time and space, the accuracy and validity of measuring instruments are challenged. The main target of this research is to investigate the application of electrical capacitance tomography (ECT), electrical resistance tomography with voltage excitation (ERTv) and electrical resistance tomography with current excitation (ERTc) on the multiphase flow with complex permittivity and conductivity distribution. The final objective based on the above research is to provide suitable tomography modual for different multiphase flow process. The experimental results show that ECT is suitable for measuring dry gas-solid fluids. ERTv is better for measuring high water content gas-solid fluids and low conductivity gas-liquid fluids, while ERTc is better for measuring continuous phase conductivity gas-liquid fluids.
Investigation of Temperature Transient Response Characteristics of Ceramic Fuel Rod of Open-Cycled Reactor
Authors: Zhou Y , Lu R B , Zhao F L , Tan S C 
Published: March 2021

Abstract
To investigate the effects of the fuel material property on the temperature safety response characteristics of the new-designed open-cycled reactor with the air as the coolant, the geometric model of the annular fuel rod is built. The parameter model is developed based on the properties of the three types of ceramic material of nuclear fuel including the Uranium dioxide (UO2), Uranium carbide (UC) and Uranium nitride (UN). The temperature transient response rule of the three kinds of fuel rods at the cases of reactor power step increase is obtained based on the fluid-structure coupling method. The temperature transient response characteristics of three types of ceramic fuel rods open-cycled reactor are analyzed. The numerical results reveal that the peak fuel temperature and the average fuel temperature increase significantly with the step increasing reactor power. The response time of the fuel rod with UC is the longest. The peak fuel temperature and the temperature difference of the fuel rod with UO2 are the highest. The relative results can lay the theoretical foundation for the fuel material selection, structure design and the safety analysis of the open-cycled reactor.
Simulation and Experimental Study on the Characteristics of the Gas Cooler in the Simulink CO2 Heat Pump
Authors: Xuan F C , Xie J , Gu Z 
Published: March 2021

Abstract
So as to research impact of inlet temperature of gas cooler on the expression of carbon dioxide hot water unit, the ambient temperature was controlled at 15 °C, and the inlet temperature was adjusted. The exhaust temperature, heating capacity, and system heat exchange capability were calculated. Testing and measuring the change of exhaust temperature, outlet temperature of gas cooler, exhaust pressure, heat exchange capability. Based on simulink simulation tools, a calculation simulation platform of CO2 heat pump water heaters was established, and a test bench of transcritical CO2 heat pumps was built. In the experimental simulation, the inlet water temperature was increased from 15 °C to 40 °C, the simulation result of the exhaust temperature increased by 14.2 °C, the heating capacity decreased by 4.69 kW, the heat pump coefficient decreased by 0.66. In the experimental result, the exhaust temperature increased by 18.7 °C, the heating capacity decreased by 4.31 kW, heat pump coefficient decreased by 0.63. The research results can provide some guidances for the practical application and optimization of transcritical CO2 heat pump system.
Simulation Study of SOFC/GT Combined Cycle System with Turbine Exhaust Recycled to Heat Fuel Cell Air Intake
Authors: Lao X S , Zhang K L , Wang W 
Published: March 2021

Abstract
For the low-temperature SOFC/GT combined cycle system used to recover the SOFC cathode intake air by using turbine exhaust gas circulation, a simulation model of the combined cycle system was established based on the lumped parameter model of SOFC, turbine, compressor and preheater. Some experimental data have verified the validity of the zero-dimensional model of SOFC. The system simulation results show that the air intake pressure caused by the air recirculation does not completely depend on the outlet pressure of the compressor. When the outlet pressure of the compressor is between 0.2MPa and 0.5MPa. The intake pressure of the SOFC will decrease to varying degrees, and it depends on the proportion of the exhaust gas recirculation. The compression ratio is not related to the output power and efficiency of the SOFC. Increase in compression ratio will reduce the output of the turbine, resulting in a reduction in the overall efficiency of the system.
Investigation on the Effect of Dead Time on the Phase of Fundamental Voltage in VSI-PMSM Drive System
Authors: Chen S Z , Jiang J F 
Published: March 2021

Abstract
Both electric vehicle PMSM drive system and grid connected photovoltaic (PV) power generation need voltage source inverter (VSI). The dead time should be set properly when the power switches are turned on and off in the same bridge arm of VSI. During the dead time, the load is out of control, which will cause the abnormal output voltage amplitude and phase. However the influence of dead time on the output fundamental voltage phase has not been paid much attention to and studied. Firstly, in the paper, the phase shift of output fundamental voltage caused by dead time is simulated and analyzed for three-phase VSI - resistance inductance series (RL) load system under several conditions such as variable switching frequency, modulation index, output fundamental frequency and dead time. Secondly, take three-phase VSI - permanent magnet synchronous motor (PMSM) drive system for instance, the simulation analysis of output fundamental voltage phase shift and rotor positioning error caused by dead time are also performed, and an off-line method to compensate the fundamental voltage phase based on αβ coordinate is given. The above work provides a reference for further understanding the influence of dead time on fundamental voltage phase shift in VSI, so as to improve the monitoring and control precision of electric vehicle drive system. The analysis approach can be applicable to the grid connected photovoltaic (PV) power generation PMSM servo system.
Numerical Study on the Coupling Process of Supercritical Heat Transfer and Combustion in the Boiler
Authors: Zhao Z X , Ma C , Li Y Q , Lu D , Lin Y S , Liu Y , Dai C H , Xiao Q , Gou J L 
Published: March 2021

Abstract
The conjugate heat transfer from in–furnace combustion to in-tube supercritical fluid has been numerically investigated in this study. The mathematic model of the conjugate heat transfer process has been constructed. The effects of the heat transfer phenomenons of supercritical fluid in tube and combustion status change in the furnace on the conjugate heat transfer process were analyzed. The results show that the RNG (Renormalization-group) model can better simulate the heat transfer process in the tube and the combustion process in the furnace than the AKN (Abe-Kondoh-Nagano) model. The difference between the two turbulence models for the furnace simulation focuses on the distribution in the high temperature region and the region of the recirculation region.
Research on Drag Reduction Mechanism and Optimization Design of Bionic Jet Flow
Authors: Chen K , Wei Z G , Lin Y S , Zhao X F , Qi X , Huang C H , Yang X H , Zhou H K , Ke H B 
Published: March 2021

Abstract
In the process of sailing, the frictional resistance of underwater objects must be reduced, which is of great significance for improving speed, range and saving energy. Based on the inspiration of the shark breathing process, this paper simplified the water spray process from the external bronchial slit of the shark breathing to the cross-flow lateral jet process. By establishing a numerical model, the influence mechanism of the jet on the flow resistance was studied, and by analyzing different jet velocities, the change of viscous resistance reveals the influence of jet velocity on viscous resistance. The results show that the side jet can reduce the boundary layer on the surface of the object, thereby having a drag reduction effect, and the drag reduction rate can be about 10%. In addition, as the jet velocity increases, the drag reduction effect is enhanced, and at the back of the jet port the vortex is formed, the outlet pressure is reduced, and the drag reduction effect is strengthened. At the same time, the study found that the arc-shaped jet port is more conducive to the reduction of resistance.