bluuebunny/crossref_metadata_2025 huggingface dataset:
Estimation of Queue Length at Signalized Intersections based on Electronic Police Data
Authors: Wang Hao , Ju Jianmin , Wu Zhixin , Huang Meixin
Published: June 2020

Aiming at the problems of complicated traffic data detection environment in China and the larger calculation error of queue length at signalized intersections, a model of queue length estimation at signalized intersections based on electronic police data was studied. By analyzing the characteristics of travel time in the electronic police data, the jump position is extracted and the number of parking times is divided. Take the intersection of Zhongguan Road and Donghuan North Road in Ningbo as an example for simulation verification and analysis. Simulation results show that the accuracy rate of the model is over 83%, and the accuracy rate during peak hours is 90.8%, which has good adaptability.
Investigations on Linear Manoeuvres of Underwater Towed Cable in Current
Authors: Gong Liangkui , Wang Wenkai , Li Shizhen , Liu Yanjun , Yu Hui
Published: June 2020

In this paper, a numerical method for dynamic characteristics of cable in marine linear towage is proposed. The governing equation of the towing system is established based on the lumped mass method. The continuous dynamic characteristic partial differential equation is obtained by the discretization of cascade nodes. The equation is solved by the finite difference time domain method. Through numerical simulation, the tension variation curves and cable response configuration under three different operating conditions-when there is no current, along with and against sea current directions-are given respectively, which can be used for dynamic load estimation and motion trajectory prediction in towed-array systems. The comparison between the numerical example results and the experimental demonstrates the validity of the method and is of practical significance for improving maritime safety and operational efficiency.
Research on Ship Management ERP Integrated Platform System of Offshore Engineering Exploration and Scientific Research Enterprise
Authors: Shan Zuolin
Published: June 2020

This article reviewed the marine exploration and scientific research enterprises in the process of marine exploration, to control the ocean fleet, including personnel, materials, finance, and other aspects of a centralized control, but due to the special characteristics of the marine exploration and scientific research industry industry, Design a comprehensive management platform specifically for marine engineering exploration. This platform can effectively control the exploration of ocean-going marine fleets. The purpose of this article is to efficiently manage the marine engineering activities. This article studies a large amount of data and based on the management of related enterprises, a comprehensive ship management and control ERP platform system has been developed. This system can effectively control the ocean fleet, and it is convenient for scientific research units to manage and control the entire process of marine exploration, effectively control financial costs, and can more efficient management of offshore engineering exploration activities, this system can achieve the characteristics of high efficiency.
Simulation Study on the Effect of Uneven Fuel Injection of Each Hole on the Combustion Process of Ethanol-Diesel Blend Fuel
Authors: Liang Yu , Zhou Liying
Published: June 2020

The small diesel generator has been widely used. When compared with vehicle diesel engine, it has stable working speed, small load variation range and lower requirements for fuel performance, so the fuel ethanol can be more easily applied for the diesel generator. The blend fuel containing 5% ethanol and 95% diesel (E5D95) is tested on a generator powered by F186. A 3D combustion model based on the injection position and angle of each hole of the diesel engine is established and verified by using the test data. Based on the measured injection rate of each hole of the 4-hole diesel injector, the even injection rate of each hole and the measured uneven injection rate of each hole are made as the injection settings for the combustion simulation. The effect of the uneven injection rate of each hole on the combustion process of ethanol-diesel blend fuel is comparatively analyzed. Due to the uneven injection of each hole, the ignition starting point is moved forwards, the maximum pressure and temperature in the cylinder are higher, NO generation is larger, soot generation is slightly smaller, and the emission of HC and CO is higher.
Research on polymer flooding inefficient oil well treatment method
Authors: Zhang Liying
Published: June 2020

During the development of polymer flooding, due to factors such as the heterogeneity of the reservoir, some inefficient oil wells appeared in the area. In order to reduce the effect difference between oil well groups and improve plane contradictions, we The division of the inefficient oil wells and the analysis of the causes, and adopting effective treatment countermeasures, this method promotes the effectiveness of the inefficient oil wells, can improve the overall development effect of the polymer flooding, and the method further perfects the polymer flooding comprehensive adjustment technology.
Research and Development of the First Generation of Multifunctional Home Fitness Recliner
Authors: Wang Shuai , Chen Xingwang , Peng Shuhui , Han Lidong , Zhang Ye , Zhou Yunkun , Xiang Meng , Yang Huilan
Published: June 2020

The first generation of multifunctional home fitness recliners is a kind of home-use portable fitness equipment that coexists with multiple functions and can be easily adjusted for strength. The fitness equipment adopts the bionic “fish-shaped” design, and uses the principle of morphological bionics to achieve the simplicity required by design and meet today’s aesthetics. While improving the aesthetics of the design equipment, it also meets the requirements of ergonomics, thereby improving the user’s sports experience. The device uses polyformaldehyde plastic, ABS plastic, shell ABS plastic (natural plastic in the groove), polyamide fiber, PVC artificial leather, plywood, sponge, rubber sponge and other plastic materials that meet national standards. 35 # steel, cold rolled steel rectangular tube, spring steel, tungsten steel and other materials that meet various technical indicators. Under the premise of safe use of equipment, multiple exercise uses can be realized.
Fluid simulation analysis of gas stove based on multi-jet cutting circle
Authors: Yang Rongqian , Zhao Lida , Zhang Jiankang
Published: June 2020

This project aims to apply the principle of multi-jet cutting circle to transform the gas stove, improve the combustion efficiency of the gas stove, reduce the proportion of exhaust gas in the exhaust gas, and reduce the exhaust gas pollution of the gas stove. In this paper, Ansys software is used to conduct fluid simulation for gas stoves with different number of pipelines, and the influence of different number of ejector pipelines on combustion products, temperature and other results is obtained.
Influence of basic motion on dynamic balance accuracy
Authors: Xiao Sa , Cui Huanting , Qin Mengtong , Chen Hong
Published: June 2020

Due to the complex environment of rotating machinery, rotating machinery is inevitably affected by environmental excitation. The basic motion excitation in environmental excitation will affect the dynamic response of the rotor. In order to study the impact of basic motion on the judgment of the rotor imbalance, the establishment of rotor motion is adopted. Differential equations and finite element simulation methods for dynamic equilibrium experiments. The results show that when the frequency of the basic motion excitation is the same as the unbalanced excitation in the system, the basic motion excitation will affect the amplitude and phase of the power frequency, and then affect the judgment of the rotor imbalance amount, resulting in a certain balance error and impact. Dynamic balance effect, but unlike unbalanced excitation, the direction of the force generated by the basic excitation will not change, so when the vertical amplitude and phase of the generated force of the excitation is used as a reference, the impact caused by the basic motion can be avoided.
Study on the Pipeline Fragility Appraisal Indicators Affected by landslide Based on Numerical Simulation
Authors: Han Bing , Fu Qiang
Published: June 2020

The completeness of pipelines is tremendous influenced by landslide in unfavorable geological conditions. The quantifying appraisal techniques is a valid means for risk management of pipelines affected by geological disasters. By using the finite element method to simulate going steadily downhill, mechanics characteristic of pipeline and pipe/soil interaction with changes in physical dimension consisted of the landslide area (LA), landslide thickness (LT), pipeline length in landslide (PLL), calibre (CA) and wall thickness (WT) of pipeline, the fragility appraisal system of pipeline affected by landslide can be constructed. The regular pattern of stress and strain variation of pipeline affected by landslide can be acquired with number analysis and computeration. The results show that the physical dimension of landslide and the PLL have strong effect on pipeline fragility, and the effect increases with increasing of the above indicators; the WT has a smaller role of pipeline fragility and the effect can be ignored. In the end, the weighting factors and marks of every fragility appraisal indicator can be given on the basis of the above conclusion.
Research and Design of a New Rotary Blast Dryer
Authors: Bo He , Shuai Cui , Hao Li , Liu Shuning
Published: June 2020

The vertical shock screening and drying machine is mainly composed of a drying box located at the upper part and a screening box body located at the lower part for drying and sieving wet materials. The device designs a superheated steam recovery device to collect the superheated steam during the drying process. There are two main applications for collecting collected hot water vapor. The first is that passing it into the heating box to heat the filling chamber in the drying box. And the second is preheating cold air to reduce the amount of heating energy. An LC shocking device is arranged in the drying box to make the wet material uniformly distributed on the material plate. And at the same time, it can promote the heat transfer area between the wet material and the hot air, thereby improving the energy utilization efficiency of the system. Using a porous grading sieve, the lower screening device can screen materials of different particle sizes at one time. The vertical shock screening and drying machine can effectively improve the utilization rate of energy and the emission of pollutants in the drying process. Thereby, it can achieve the energy saving and the emission reducing.
Study on drilling mechanism of combined bit in hard coal seam
Authors: Li Yan , Shi Wenbao
Published: June 2020

Borehole pressure relief can effectively reduce the accumulation of elastic energy of working face and surrounding rock mass, and reduce the regional impact risk. But in hard coal seam, drilling jam, holding and other dynamic phenomena often occur in drilling, which seriously reduces drilling efficiency. Therefore, aiming at the problem of poor coal breaking effect of traditional geological drills in hard coal and rock, the coal breaking characteristics of new type combined drills are studied by theoretical analysis and numerical simulation. Considering the traction, rotation and impact movement in practical work, the trajectory model of combined drills is put forward. The coal breaking characteristics of the two kinds of drills are compared and analysed from the aspects of the difficulty of coal breaking and the force fluctuation of the drill bit. The results show that the combined bit can reduce the difficulty of coal breaking by 50% when its hardness value is twin 6, and the combined bit can reduce the force of nearly 7000N in hard coal and rock in the fluctuation of force acting on the geological bit. Therefore, the study of coal breaking characteristics of the combined bit can effectively improve the special rock mass such as broken hard coal and rock.
Summarization of Vehicle Position and Azimuth Fast Determining Technology
Authors: Yang Chen , Cai Yuanwen , Xin Chaojun , Wang Huaipeng , Shi Meiling
Published: June 2020

To improve the rapidity, accuracy and autonomy of vehicle position and azimuth determining is an important theme in the development of land launch equipment. Based on this topic, a comprehensive summary is made of the theories and methods related to vehicle position and azimuth determining technology, including autonomous integrated navigation, initial alignment technology, error estimation and compensation technology, observability analysis method, and nonlinear filtering method. By summarizing and analyzing the related progress in recent years, this paper points out the existing problems in the research, and probes into the development direction of vehicle position and azimuth fast determining technology.
Development Status of High Voltage Insulation Technology
Authors: Sun Jiaqi
Published: June 2020

High-voltage insulation technology is a technology related to the development, selection, design, manufacture, operation and maintenance of high-voltage electrical equipment insulation structures. In high-voltage electrical equipment, insulation structures are used to separate conductors with different potentials, so the insulation structure is an important part of electrical equipment. With the increase of power consumption and the increase of transmission distance, the maximum voltage level of the power system will be further increased, and it is becoming more difficult to solve the insulation problems related to high-voltage electrical equipment. This article gives a brief description of sulfur hexafluoride gas insulation, power cable and power transformer insulation technologies. In addition, new insulation materials and improved manufacturing processes can be introduced to improve the electrical insulation strength.
Research on Security Defence System of Cooling Water Source in Nuclear Power Plant
Authors: Wu Qiaojun , He Guangchu , Wen Hongyong , Lin Xinpeng , He Shengliang , Chang Xincai
Published: June 2020

Nuclear safety is the lifeline of nuclear power development, the premise and foundation of nuclear power development. The safety of cooling water source is an important part of nuclear safety. The safety of cooling water source of nuclear power plant is related to nuclear safety, and it is the final heat sink of nuclear power plant, which undertakes the safety function of reactor residual heat export. Littoral nuclear power plants take seawater as the cooling water source. When the solid suspended solids, floating objects and marine organisms in the seawater exceed the filtering and cleaning capacity of the cooling water filtering equipment, the water intake or filtering equipment will be blocked and unable to provide the required cooling water, which will cause the cooling water source safety event. In view of these problems, this paper proposes to optimize the cooling water source security defence system in depth, improve the cooling water source risk monitoring and early warning system, establish the cooling water source overall status monitoring platform, and improve the emergency response and unit control capacity of the power plant.
Parallel Stability Analysis of Generator and Inverter in Independent Micro grid
Authors: Gao Mingyu , Liu Jinning
Published: June 2020

In the independent micro grid system, the generator set and the new energy grid connected inverter are both important components of the system. To solve the problem of stability of the parallel of the inverter and synchronous generator, this paper studied the droop control and the virtual synchronous machine control principle, analyzed their similarities and differences and essential characteristics; established the small signal model of the parallel system of the inverter generator set, analyzed the stability of different structural systems. It Comed to conclusion that the stability of the virtual synchronous machine control in the parallel system was stronger, and the system simulation model was built by Matlab / Simulink software to verify the theoretical analysis results.
Renewable Energy Generation and Load Classification based on H-K compound clustering algorithm
Authors: Sun Yong , Li Zhenyuan , Li Dexin , Liu Chang , Wang Shengyan , Qiu Fengkai , Zeng Ming
Published: June 2020

In this paper, the uncertainty of diesel generator (hereinafter referred to as DG) output and load demand is studied by multi scenario analysis. Firstly, this paper studies the timing characteristics of DG power generation and load demand, and describes the annual and daily distribution of photovoltaic power generation, wind power generation and load demand. Then it introduces the method of multi scene analysis, describes the process of dealing with the uncertainty in multi scene in detail, and generates enough scenes through the density function of classification probability to get the probability of each scene. Finally, H-K compound clustering algorithm is used to solve the above problems. The scale scene is compressed to get a typical “planning scene”.
Research on the Coordinated Scheduling and Development of Renewable Energy Power Generation and Nuclear Power
Authors: Duan Lili
Published: June 2020

From 2016 to 2017, China experienced a considerable degree of wind abandoning and light abandoning. The average utilization hours of nuclear power decreased significantly and the power loss of nuclear power was serious. In regions where clean energy consumption is limited, the optimal scheduling and coordinated development of renewable energy and nuclear power will be a problem for some parts of China. According to China’s current energy-saving power generation scheduling method, wind power and photovoltaic power generation scheduling ranking before nuclear power. To maximum benefits of the whole society as a starting point, from the economic, environmental protection, power grid friendly, safe and international experience, analysis of wind power, solar and nuclear power scheduling sequence comparison, suggest the authorities to properly optimize existing power generation scheduling order, will arrange before the wind, nuclear power unit scheduling order also suggested that nuclear power provinces in the development of clean energy planning, the reasonable rhythm control of wind power development, facilitate clean energy given solution.
Excavation and support construction of rock wall crane beam layer in underground powerhouse of a pumped storage power station
Authors: Chen Jie , He Yi
Published: June 2020

Rock wall crane beam construction is the focus and difficulty of underground powerhouse construction. The quality of its excavation molding will directly affect the operation safety of the plant bridge crane. This article introduces the excavation procedure of rock wall crane beam for the underground powerhouse system engineering of a pumped storage power station And method, anchor rod construction, net hanging, and spraying construction have achieved good results, and have certain reference value for excavation and support construction of rock wall crane beams in similar projects.
Study on Energy Coordination Mechanism of Micro Photovoltaic Grid Connected Inverter
Authors: Zhang Enmu , Shen Yong , Wang Wenbin , Feng Peilei , Xu Tianqi
Published: June 2020

In this paper, the non isolated grid connected inverter control strategy is adopted. The simulation model of photovoltaic grid connected inverter is built in MATLAB. Realize the same frequency and phase of grid connected current and grid voltage, the sine degree of grid connected current waveform is better, and realize the islanding detection function. In the experiment platform, the control idea is further verified, and the simulation is proved to be correct.
Reactive power optimization of AC and DC system based on improved genetic algorithm
Authors: Ren Lei , Zhang Jian
Published: June 2020

In the context of the rapid development of DC transmission, this paper studies the multi-objective reactive power optimization of AC and DC transmission systems. By studying the relevant basic knowledge, it provides a theoretical basis for studying reactive power optimization of AC-DC distribution networks. This paper provides an improved genetic algorithm that uses node voltage offset and total active network loss as two objective functions. A fast non-dominated sequencing genetic algorithm with elite strategy NSGAII is applied to the multi-target reactive power of AC and DC systems. During the optimization, a corresponding reactive power optimization program was written, and the feasibility of the proposed method was verified by an example of the IEEE 9-node system.
Research on Statistical Model of Japanese-Chinese Name Translation for Japanese Kana
Authors: Yu Xiaoling , Liu Xin
Published: June 2020

In view of the lack of bilingual resources in Japanese-Chinese translation, and the naming entity of Chinese character naming entities, especially Japanese pseudonyms, it is difficult to use, so the Japanese-Chinese pure pseudonym translation is a statistical translation model. The model has been applied so far and there have been many problems. The first is limited by the size and quality of the parallel corpus, and the second is the lower accuracy of the translation. Based on this, the paper proposes a statistical model of Japanese pseudonymous Japanese name translation based on inductive learning method. This method can extract Japanese and Chinese named entities from Japanese and Chinese corpora, and convert them into Roman alphabet and Pinyin sequence. Example screening after similarity calculation. Then, the instance-based induction learning method is used to automatically obtain the Japanese-Chinese transliteration rule base of the named entity, and iteratively reconstructs the transliteration rule base through feedback learning. Through experimental research, it is found that the Japanese-Han name translation statistical model method for Japanese kana is simple and efficient, and the translation accuracy is overcome while overcoming the dependence on bilingual data.
Research on Fabric Image Retrieval Method Based on Multi-feature Layered Fusionon
Authors: Ji Yunrong , Wang Weidong , Lv Yamin , Zhou Weirun
Published: June 2020

In recent years, with the maturity of computer technology and the increasing development of Internet technology, online transaction has become an important and popular sales method. As a necessities of life, clothing accounts for a considerable proportion of online transactions. Whether it is clothing manufacturers buying fabrics, or customers buying clothing online, they rely on fabric images on the Internet to browse, compare and select satisfactory products. This method of manual comparison is both time consuming and error prone. To effectively manage and use the fabric, it is very important to establish a fabric image retrieval system. The variety of fabrics and various styles, and the fabric image itself has the characteristics of large amount of data and large amount of information. The traditional retrieval method cannot achieve fast and accurate retrieval of fabric images. This paper proposes a retrieval method based on multi-feature fusion, which can accurately analyze the characteristics of fabric images. Experiments show that the using this method to retrieve fabric images can achieve good results.
Multilingual Recognition Based on Neural Network with High Recognition Degree
Authors: Jiang Yanhong , Zhan Xuegang , Lan Yixiao
Published: June 2020

Language recognition has become an important branch of natural language processing. Due to the interference of out of vocabulary words and the same words in different languages, it has been a challenging task to accurately identify language categories with high similarity. In this paper, N-gram is combined with word2vec to process the data, MLP and CNN models are selected for improvement and experimental analysis. The experimental results show that the data processing and model training of 20 kinds of highly acquainted languages are used in the above-mentioned way, which reduces the dependence of the model on the size of the data set and the length of the text, the accuracy of the model detection between the languages with high recognition degree is improved, and the robustness of the language recognition model on different data sets is enhanced, with the accuracy rate being over 97.
Discussion on the construction of intelligent frame repair platform for subway vehicles
Authors: Zhang Haoran
Published: June 2020

Based on the construction and implementation process of an intelligent management platform for rail transit vehicle maintenance, this paper expounds the construction, implementation and application of the intelligent management platform for rail transit vehicle maintenance in view of the development status of the operation and maintenance of rail transit vehicles in our country, so as to provide reference for relevant professionals of rail transit.
A Wearable and Portable Real-Time Control Gesture Recognition System for Bionic Manipulator
Authors: Cao Tianao , Liu Dan , Wang Qisong , Bai Ou , Sun Jinwei
Published: June 2020

The dexterity and coordinated movement of the hand play a very important role in people’s daily life and interpersonal communication. For patients with hand amputation, there are many inconveniences in life. However, prosthetic limb can help them to carry out daily life in accordance with their own intention to meet the basic grasp and interpersonal gesture needs of daily life, which can greatly improve the quality of life of patients. The bionic manipulator is such a humanoid prosthetic limb for the rehabilitation of amputees and is controlled by the surface electromyography (sEMG) signals on the surface of the human body. In this paper, a wearable and portable gesture recognition system based on pattern recognition algorithm is established to control the bionic manipulator in real time. We enhanced the accuracy in each step of signal acquisition and processing. By analyzing the mechanism and characteristics of sEMG signals, we determined the gestures to be identified, the areas of muscle, the number of electrodes, and the placement positions. Our self-developed acquisition device was used to acquire 4-channel forearm sEMG signals and data preprocessing, window sliding, feature extraction, gesture classification were conducted.
Risk Analysis for Railway Signaling Safety Data Network Based on Extend Bayesian Attack Graph
Authors: Liao Yuanyuan , Wang Jian , Tian Kaiyuan , Wang Xuyu , Cai Baigen
Published: June 2020

The railway signaling safety data network is a key network to ensure the safety of train operation and improve transportation efficiency. Its information security is closely related to the safe and efficient operation of trains. This paper proposes an extend Bayesian attack graph model for risk analysis of railway signaling safety data network. Based on the traditional Bayesian attack graph, the model introduces the protection node, and describes the causality among network attack, protection and network state through the Bayesian network. First of all, based on the analysis of the vulnerabilities and possible malicious attack paths in the railway signaling safety data network, the extend Bayesian attack graph model is established with the system functional safety accidents as the target nodes. Then calculate the probability of functional safety accidents by Bayesian network, and combine the impact of different accidents to evaluate the risk of system information security. In addition, according to different attacks and the implementation of different protective measures, evidence node state can be set up, and the extend Bayesian attack graph model is able to use Bayesian inference to analyze the system risk.
Research on Green Logistics Scheduling System of Textile Vehicle Automatic Guided Vehicle
Authors: Wang Chenxi , Wang Zhen
Published: June 2020

With the rapid development of science and technology, China’s modern manufacturing technology has developed and progressed rapidly, and the degree of automation of intelligent production workshops has gradually increased. Enterprises are facing huge challenges in path optimization and energy conservation and emission reduction. This paper mainly studies the problem of AGV green intelligent logistics scheduling in textile workshops. First, an AGV logistics scheduling optimization model with the goal of reducing AGV energy consumption and optimal AGV path is established, and then an improved genetic particle swarm optimization algorithm with task sequencing as the constraint is proposed. Take the actual scheduling data of a textile workshop as an example to verify the method in this paper. From the calculation results, the AGV logistics scheduling model proposed in this paper can better simulate the energy consumption problem of AGV green scheduling. The improved genetic particle swarm algorithm proposed has a better optimization ability and a faster speed in solving such problems. Speed of convergence.
Preparation and Management of In-service Inspection Schedule Program in Nuclear Power Plants
Authors: Li Tian , Xue Donglin , Yan Hai , Yin Qin
Published: June 2020

In-service Inspection (ISI) schedule program for nuclear island equipment was of the important part of ISI program file system in nuclear power plants (NPPs), which acted as a connecting link. Based on ISI rules for the mechanical components of PWR nuclear islands (RSE-M) and the plant ISI general program, the preparation method for schedule program of CPR1000 units were presented. It focused on the analysis and discussion of the existing problems during the preparation, upgrade and management process and some targeted suggestions were put forward. It may lay a foundation for a further optimization of the ISI program file system and the smooth implementation of the ISI activities.
Research on the Application Scheme of Air-conditioning Load Regulation for Peak Shifting in Power Grid
Authors: Zhou Xu , Li Siwei , Tian Shiming , Luan Kaining , Yue Liang , Liu Xiaodan
Published: June 2020

With the growth of the national economy and people constantly improve the level of electricity load has maintained a faster, higher growth, the growing impact of the growth of the air conditioning load on the power system economic operation of power supply and demand balance. The grid load clipping the air conditioning load regulation, we design a smart grid shift peak air-conditioning load regulation. The article describes the grid load characteristics of the current economic situation, the load control for the different forms of communication networking chip design and intelligent centralized control of air conditioning load platform design, also described the entire system of communication networking solutions and peaking strategy.
Optimization model and algorithm on electrical resolver position of high speed railway
Authors: Wen Jing , Bai Yun , Li Sai , Yuan Bo
Published: June 2020

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

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

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

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

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

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

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

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

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

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

This 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

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

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

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.