bluuebunny/crossref_metadata_2025_split huggingface dataset:
Optimization model and algorithm on electrical resolver position of high speed railway
Authors: Wen Jing , Bai Yun , Li Sai , Yuan Bo 
Published: June 2020

Abstract
The position of resolver of electrified railway affects inter-station run-time and energy consumption of train movement. Considering the constraints on train operation, signal distance as well as the number and distance requirements of electrical resolver, this paper presents an mathematical model to optimize the position of electrical resolvers for the whole line with the objective to minimize the weighted sum of train inter-station run-time and energy consumption. Genetic algorithm is employed to solve the proposed model. Case studies on Wuhan-Guangzhou high speed rail line from Chibi North to Yueyang East show that the proposed model saves 3.14% of train inter-station run-time and 1.28% of train energy consumption compared with the real-world electrical resolver configuration.
Research on Electromagnetic Flowmeter Based on Double-frequency Trapezoidal Wave Excitation
Authors: Li Zhengyu , Huang Qi , Duan Yudan , Chen Weiqi , Zou Lu 
Published: June 2020

Abstract
Electromagnetic Flowmeter is widely used in industrial production and life, because it is characterized by high precision and little environmental interference in electromagnetic flow measurement. However, the commonly used low frequency rectangular wave excitation greatly reduces the measurement accuracy and measurement range of electromagnetic flowmeter due to in-phase interference, differential interference and other factors. Double-frequency trapezoidal wave excitation has the advantages of both excellent zero-point stability of low frequency excitation and strong ability to suppress the noise of slurry fluid and fast response speed of high frequency excitation. In this paper, a double-frequency trapezoidal wave excitation method for electromagnetic flow measurement is proposed. Then the experimental platform is established to verify the measurement accuracy and measurement range. According to the comparison with the instant flow of the standard meter, the measurement accuracy of double-frequency trapezoidal wave excitation is significantly higher than that of low frequency rectangular wave excitation, and in phase interference and differential interference are significantly reduced.
Adaptive analysis of main transformer protection in hybrid wind farms
Authors: Liang Jiayu , Yang Bingyuan , Liu Hongjin 
Published: June 2020

Abstract
With the development of wind power technology, wind farms have gradually formed a mixed operation pattern dominated by DFIG and PMSG. By analyzing the short-circuit current characteristics when a fault occurred in the main transformer protection zone of the wind farm and the hybrid wind farm is connected to the grid, the possible impacts of the short-circuit current of the hybrid wind farm on the protection of the transformer is studied. The results show that after mixing different unit types, when the fault occurs in the main transformer protection zone of the wind farm, the short-circuit current contains the second harmonic component, and its attenuation speed is related to the number of PMSG, the number of DFIG, the fault location, and the severity of the fault. Under the influence of above factors, the blocking time of the second harmonic blocking protection will be prolonged, thereby increasing the operating time of the ratio differential protection.
Design and Application of Linear Phase-shifting Transforme
Authors: Xu Hao , Zhao Jinghong , Ma Yuanzheng 
Published: June 2020

Abstract
In power conversion equipment, the Phase-shifting Transforme plays an important role in reducing harmonic pollution and improving the quality of output waveform. Based on the principle and structure of linear motor, a linear phase-shifting transformer is designed in this paper to overcome the disadvantages of the traditional phase-shifting transformer with complicated winding structure and difficult expansion. This paper introduces the basic principle of the linear phase-shifting transformer, deduces the relevant formulae of the electromagnetic design of the linear phase-shifting transformer, carries out the finite element simulation, applies the linear phase-shifting transformer to the multiple stacked inverter system, and proves the effectiveness of the designed linear phase-shifting transformer.
Research on Vector Sequence Optimization of Five-phase SVPWM
Authors: Ma Yuanzheng , Zhao Jinghong , Zhou Yinping 
Published: June 2020

Abstract
In the multi-phase motor drive system, the five-phase motor is the typical representative. But the increase of the number of phases causes the number of IGBTs used by the inverter multiplied, and the use of SVPWM control with high frequency on and off causes the inverter switching loss increased, thus the inverter produces a lot of heat. In this paper, by adjusting the action order of effective vectors in SVPWM and the insertion position of zero vectors, a vector sequence optimization SVPWM technology is proposed. Compared with the conventional NFV-SVPWM technology, under the same frequency the switching times are reduced to 40% of NFV-SVPWM. The vector sequence optimization SVPWM and five-phase induction motor was simulated in Simulink. The simulation showed that the vector sequence optimization SVPWM introduced few harmonic content and the stator phase current distortion of the motor was low.
Influence of Polarization Crosstalk of Y Branch Loop on Scale Factor in Fiber Optic Current Sensor
Authors: Yu Jia , Wang Xiaxiao , Li Chuansheng 
Published: June 2020

Abstract
The influence of polarization crosstalk of Y branch loop on scale factor is analyzed in detail. In the Y branch loop, the scale factor is affected by only the output alignment angle of the PBS. The experiment result shows the range of output alignment angle of the PBS should not exceed from 0.2 to 2.5 over a range from - 40°C to 70°C which corresponds to angle 1.8 at room temperature to make sure the measurement accuracy within ±0.2% from 0 to 100kA.
Application of an Ensemble Learning Method in the Risk Prediction of Electricity Tariff Recovery
Authors: Wu Huaiguang , Zhang Mingxing , Jin Baohua 
Published: June 2020

Abstract
Electricity tariff recovery has always been an important part of power companies. However, there are often some users who are in arrears in electricity charges. Therefore, how to make effective risk assessment for electricity customers is the key work at present. In this paper, an ensemble learning method named gradient boosting decision tree-random forest-adaboost-logical regression (GRAL) is proposed to construct a risk prediction model of electricity tariff recovery. Firstly, the data provided by the power company was preprocessed with feature engineering. Secondly, the GRAL ensemble learning method and the traditional logistic regression algorithm are used separately to construct the risk prediction model of electricity tariff recovery to predict the probability that the user will default next month. Finally, we make a risk assessment for users according the probability and predict whether the user in different risk levels will be in arrears. Experimental analysis shows that the proposed GRAL ensemble learning method has better experimental results compared with the traditional logistic regression algorithm, this method can effectively evaluate the payment behavior of power customers and make a more accurate prediction about whether users will be in arrears.
Research on the combined predicting model of short-term load in smart grid
Authors: Sun Liping , Wang Lifang , Jing Siwei , Peng Zhou , Yao Fangling 
Published: June 2020

Abstract
As an important basis of power grid planning and dispatching, short-term load predicting model with high accuracy is very important to ensure the efficient and reliable operation of power grid. In this paper, the influencing factors of the short-term load of smart grid are determined by the method of grey correlation analysis. BP, RBF and Elman neural network construct the single prediction model of the short-term load of smart grid. The single prediction model is weighted by GA genetic algorithm, and the combined prediction model of the short-term load of smart grid is constructed and verified by an example. The results show that the error of the combined prediction model can be kept at about 0.4%, which has higher prediction accuracy and stability.
On the Comparison of Gauss and Hybrid Methods and their Application to Calculation of Definite Integrals
Authors: Imanova M N 
Published: June 2020

Abstract
As is known there is the wide class of methods for calculation of the definite integrals constructed by the well-known scientists as Newton, Gauss, Chebyshev, Cotes, Simpson, Krylov and etc. It seems that to receive a new result in this area is impossible. The aim of this work is the applied some general form of hybrid methods to computation of definite integral and compares that with the Gauss method. The generalization of the Gauss quadrature formula have been fulfilled in two directions. One of these directions is the using of the implicit methods and the other is the using of the advanced (forward-jumping) methods. Here have compared these methods by shown its advantages and disadvantages in the results of which have recommended to use the implicit method with the special structure. And also are constructed methods, which have applied to calculation of the definite integral with the symmetric bounders. As is known, one of the popular methods for calculation of the definite integrals with the symmetric bounders is the Chebyshev method. Therefore, here have defined some relations between of the above mentioned methods. For the application constructed, here methods are defined the necessary conditions for its convergence. The received results have illustrated by calculation the values for some model integral using the methods with the degree p ≤ 8.
On the error term in the prime geodesic theorem for SL4
Authors: Gušić Dž 
Published: June 2020

Abstract
In this paper we pay our particular attention to the error term in the prime geodesic theorem for compact symmetric spaces represented as double coset spaces of the special linear group of order four over real numbers. It is known that in the case of compact locally symmetric Riemannian manifolds of strictly negative sectional curvature, the corresponding error term depends on classification of Riemannian symmetric spaces of real rank one. In particular, the error term is a function depending on the dimension of the underlying locally symmetric space. In this research we prove that the error term in the case at hand is a function depending on the degree of the polynomial that appears in the functional equation of the corresponding Selberg zeta function.
Time-fractional classical Black-Scholes option pricing model via He-separation of variable transformation method for exact solutions
Authors: Edeki S. O. , Akinlabi G. O. , Egara F. O. , Nzeadibe A. C. 
Published: June 2020

AbstractThis paper considers the exact solutions of the time-fractional classical Black-Scholes option pricing model through the application of a method known as He-Separation of Variable Transformation Method (HSVTM). The HSVTM combines the basic properties of the He’s polynomials, the Homo-separation variable, the modified DTM, which increases the efficiency and effectiveness of the proposed method. The proposed method is direct and straight forward. Hence, it is recommended for obtaining solutions to financial models resulting from either Ito or Stratonovich Stochastic Differential Equations (SDEs).
Analysis of Financial Network Topological Dynamics of the Russian Stock Market from 2012 to 2019
Authors: Balash Vladimir , Chekmareva Alfia , Faizliev Alexey , Grigoriev Alexey , Sidorov Sergei 
Published: June 2020

Abstract
In this paper we study some properties of the Russian stock market with the application of network approaches and data-driven science. Complex networks theory allows us to construct and analyse topological network structures of the market. Among the important information which is possible to acquire from it is the relationships between stocks returns with the analysis of hidden information and market dynamics. This paper is focused on the analysis of the market network dynamics over time. We construct market networks for 75 consecutive overlapping 250-day periods to analyze the dynamics of the structural properties of the market rank-correlation-based network. Degree distribution and maximum clique size are considered as the important structural characteristics of the market network. In our opinion these parameters are the essential graph attributes and give insight into Russian financial market structure.
Characterization testing of Lockheed Martin Micro1-2 cryocoolers for the Mapping Imaging Spectrometer for Europa (MISE) instrument
Authors: McKinley I M , Mok M A , Hummel C D , Johnson D L , Rodriguez J I 
Published: June 2020

Abstract
The Mapping Imaging Spectrometer for Europa (MISE) instrument on the Europa Clipper mission will use a Lockheed Martin “high-power” Micro1-2 pulse tube cryocooler with a heat rejection temperature below 250 K. This paper describes the performance testing and results of Lockheed Martin Micro1-2 coolers optimized for these conditions. The heat reject temperature varied between 170 K and 260 K for different helium fill pressures. The coolers were driven with input powers ranging from 5 W to 40 W and drive frequency between 125 Hz and 150 Hz. For all conditions measured, the heat flow from the compressor was between 54% and 58% of the total heat and the compressor temperature was between 4 K and 6 K warmer than the expander temperature. In addition, another Micro1-2 cooler optimized for 300 K environment was subjected to a life test at reject temperatures below 250 K. The cooler performance and helium leak rate did not change over the duration of the life test. Moreover, a burst test was performed on a unit of this model of cooler that was without the internal components. Finally, a method for developing analytical expressions to curve fit cooler performance data is presented. These expressions are provided and predict cooler performance to within 15% for a fixed drive frequency over a range of cold tip temperature, heat reject temperature, and input power.
Micro-sized Cryocooler Controllers for Space
Authors: Frohling K D 
Published: June 2020

Abstract
The explosion in SmallSat and CubeSat deployments has led to a need for miniaturized cooling solutions for sensors that require cryocooling. Since there are limited opportunities for miniaturization in the thermal mechanical unit (TMU) portion of the cryocooling system, much of the pressure to reduce size falls on the cryocooler control electronics (CCE). In the world of digital electronics, continuous size reduction is the expected norm, however, in the world of power electronics this is not the case. The number of components and their variety is greatly limited when selecting space grade electronics, typically resulting in designs that make space grade electronic solutions much larger than an equivalent circuit made of commercial grade electronics.
One way to reduce the size of the power components is to switch at a higher speed. The current generation CCE devices built by Iris Technology utilize MOSFET power transistors to perform power conversion. The characteristics of the power MOSFETs limit the switch rate to something on the order of 100 kHz, thus driving the energy storage requirements of the capacitors and inductors. If we could switch faster we reduce the required energy storage and thus the size of the inductors and capacitors.
One solution to the switching frequency problem is the use of Gallium Nitride (GaN) FETs which can be switched on the order of 1 MHz. GaN FETs are inherently radiation tolerant, however recently GaN FETs have become available with space grade packaging. The space grade packaging is available with an integral radiation hardened high/low side driver. This integrated part provides further size reduction to the electronics design.
Recently, high performance space grade microcontrollers have become available. These parts offer another integration opportunity, as the FPGA and ADC functions can be combined into a single smaller chip. Space grade GaN FETs when combined with the space grade microcontrollers provide an opportunity for significant reduction in the volume required for the CCE portion of a cryocooler system.
Analysis of internal temperature distribution and its total parasitic heat leak for a cryogenic cold Compressor
Authors: Dong X B , Shang J , Su H , Wei C B , Wu J H 
Published: June 2020

Abstract
Cold compressors are the core component needed for the development of a facility for large-capacity refrigeration at superfluid helium temperatures. The compressor impeller is operated at extremely low temperature and low pressure which involves technical issues including material properties at low temperature, heat transfer, failures of the actuating motor resulting from overheating and performance penalty due to heat transfer from the warm side of the machine to the cold side. To address these issues, it is important to understand the temperature distribution inside the housing of the machine. To analyze the temperature distribution, an integrated numerical model is created on the basis of the model of the cold compressor structure and then simulated through computational fluid dynamics. The actual temperature rise of the cold compressor is measured at two temperature measuring points and compared with the temperatures predicted by the simulation to validate the accuracy of the model. The results show that the internal flow field around the motor and bearings of the cold compressor is completely turbulent and the total parasitic heat transfer to the cold gas stream is closely related to the rotating speed of the high-speed motor.
Development of a Cryogenic Compressor for Airborne Cryocoolers
Authors: Cragin K. , McCormick J. , Zagarola M. 
Published: June 2020

Abstract
Superconducting electronics and spectral-spatial holographic systems are being developed for advanced digital communications. These devices must operate at cryogenic temperatures of near 4 K. Liquid helium is undesirable for mobile missions due to logistics and scarcity, and commercial low temperature cryocoolers are unable to meet size, weight, power, and environmental requirements for many missions. Creare is developing a turbo-Brayton cryocooler that provides refrigeration at 4.2 K and rejects heat at 77 K to an upper-stage cryocooler or through boil-off of liquid nitrogen. The cooling system is predicted to reduce size, weight, and input power by at least an order of magnitude as compared to the current state-of-the-art 4.2 K cryocooler. For systems utilizing nitrogen boil-off, the boil-off rate is reasonable. This paper reviews the development of the cryo-compressor, a key cryocooler component. The cryo-compressor has heritage in the cryogenic circulator used in the space-borne NICMOS cryocooler. To produce the pressure ratios and mass flow rates required by the cryocooler, the cryo-compressor must operate at much higher operating speeds than the cryogenic circulator while still at cryogenic temperatures. This operating condition presents a challenge for stable operation of gas bearings at low viscosities. The approach to overcome this challenge and the testing of the compressor at cryogenic temperatures are the focus of this paper.
Numerical study of the effect of the helium-based multi-component gas mixture on the internal purifier
Authors: Feng G , Jia Q , Gong L , Zhang M , Xu P , Li Z , Zhu W , Ma H , Wang F 
Published: June 2020

Abstract
The performance of the internal purifier has a direct impact on the liquefaction capacity of the helium liquefier. With increasing impurity level in helium, liquefaction capacity of the helium liquefier reduced significantly. In order to ensure the helium liquefier operates safely and stable, remove the impurities from the helium in the helium liquefier and improve the utilization of the helium, it is necessary for us to develop the technology of purification. In this paper, the impact of changes of multi-component helium mixture on the performance of the internal helium has been developed numerically. The final results show that as the impurities in the helium mixture increases, the performance of the internal purifier decreases first and then increases. It can help us design more efficient and compact internal purifier.
Experience from the outsourcing of the Cryogenic Operation & Maintenance at CERN
Authors: Ferrand F , Gayet P , Guillotin N 
Published: June 2020

Abstract
CERN operates and maintains several large cryogenic systems including those serving the LHC complex and its associated detectors, together with cryogenic Test Facilities and distribution services. Outsourcing of Operation and Maintenance to an industrial partner was implemented in 2016. It allows the cryogenics group to activate different level of services starting from basic technical support up to full delegation with result oriented obligations for availability and helium inventory management by means of dedicated contractual key performance indicators. After almost three years from the implementation of this complex service contract in a context of intensive Operation & Maintenance campaigns of CERN accelerators, detectors and test facilities, this paper will report on the obtained results, emphasizing on technical, organizational and economic performance. Additionally the paper intents to share lessons learned from the implementation and follow-up of such major outsourcing. Finally the paper will describe the expected evolution of specific needs with respect to the provided services during the Long Shutdown 2 (2019-2020) of the CERN accelerators, detectors and test facilities, including the phase of resuming operation of the cryogenic plants and ancillary infrastructure.
Cryogenic system for Polish Free Electron Laser Facility
Authors: Banaszkiewicz T , Chorowski M , Duda P , Poliński J , Pietrowicz S , Czuma P , Krawczyk P , Lorkiewicz J , Nietubyć R , Sekutowicz J , Tazbir J , Terka M 
Published: June 2020

Abstract
Polish Free Electron Laser facility (PolFEL) will be the first free electron laser in Poland. The PolFEL superconducting linear electron accelerator will first consist of an electron gun and four RI-HZDR type cryomodules, each housing two 9-cell superconducting TESLA RF cavities. Such configuration allows the generation of a continuous wave and long pulse beam with 5-50 MeV of energy and a long pulse electron beam with energy up to 187 MeV and photon wavelength ranged from THz region down to 55 nm. In the second stage an extension is planned with two cryomodules, which allows to reach 300 MeV electron beam energy and extreme ultraviolet (EUV) range of electromagnetic radiation.
RF cavities will be operated at 2.0 K (optionally 1.8 K). For a four cryomodule linac the static and dynamic loads are estimated to be 61 W and 240 W @ 2 K, respectively. One of the investigated option is that the cooling power will be generated by the TCF50 Linde helium plant. The helium plant has a liquefaction capacity of 6 g/s and 120 W at 4.5K of cooling power. During the beam-on operation mode of the linac, a shortage of cooling power will be compensated by liquid helium supplied from an external dewar, while the warm helium gas stream exceeding the liquefaction capacity will be collected in pressurized storage tanks. During the beam-off mode, the helium gas will be recovered from the storage tanks and re-liquefied to the external dewar. The other option is the installation of a dedicated cryoplant fully corresponding to the linac cryogenic requirements.