bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of interfaces heat fluxes on the rheological and flow behaviours of melt in the gas-assisted extrusion of plastic micro-tube
Authors: Ren Zhong , Huang Xingyuan
Published: August 2019

In this study, the effects of interfaces heat fluxes on the rheological and flow behaviors of melt in the gas-assisted extrusion of plastic micro-tube were numerically investigated. In the numerical studies, the heat transfer effect at the interfaces between the annual melt and two layers of assisted gases were considered. Under four different heat transfer coefficients, the radial and axial velocities, pressure, temperature, and viscosity distributions along the axial direction of die were obtained. Numerical results show that, in the gas-assisted extrusion of plastic micro-tube, with the increase of interfaces heat fluxes (heat transfer coefficient), the radial velocity, axial velocity, and temperature distributions of melt gradually increases, but the pressure, viscosity of melt gradually decreases. At the same time, the larger interfaces heat fluxes will result in the better flowability of melt in the gas-assisted extrusion of plastic micro-tube.
Effects of Sm on Microstructure of Mg-12Gd-2Y-0.5Zr Alloy
Authors: Li Kejie , Xu Haojie , Tong Zhangming
Published: August 2019

By alloy melting, microstructure analysis and micro-hardness test, the effects of Sm addition on the microstructure of Mg-12Gd-2Y-0.5Zr alloy with solution treatment and aging treatment were investigated. The results showed that the microstructure of the tested alloy consisted of α-Mg matrix, Mg41Sm5, Mg5Gdm, Mg24Y5 and β’ phases, and Sm improved the micro-hardness value of α-Mg matrix attributed to its better solid solution strengthening effect in α-Mg. The micro-hardness of the alloy with Sm increases obviously from HV121.4 to HV134.3 when compared with that of Mg-12Gd-2Y-0.5Zr alloy.
Epitaxial ZnO on p-Si and its MSM Structure Photoconductive Ultraviolet Detector
Authors: Zhong Wen’an , Liu Jianfeng , Zhao Yu , Zhang Quanlin , Zhao Yijun , Wang Yuchao
Published: August 2019

In this work, a plasma-assisted molecular-beam epitaxy (PA-MBE) was used to prepare high-quality ZnO thin films on p-type silicon substrates. Be/BeO composite buffer layers were designed to improve the crystal quality of ZnO thin films. Based on the ZnO thin films, we fabricated interdigitated electrode MSM structure photoconductive UV detector by lithography, electron beam evaporation and other traditional semiconductor processes. In addition, dark current, spectral response of the UV detector were measured by responsivity testing system to explore the application of ZnO based UV detectors.
Study on Fretting Wear Properties of High Speed Diesel Engine Roller Tappet Material Cr12W Steel
Authors: Guo Xiaolong , Cai Yuqing , Lai Fuqiang , Wang Jialin , Li Zhengxian , Qu Shengguan
Published: August 2019

The cam and tappet are key components of the internal combustion engine valve train system. Due to the alternating high-frequency cyclic of high contact stress, the cam and tappet are prone to abnormal wear and failure. In this work, Cr12W steel was selected as the material of the roller tappet in valve train. Then, it was treated by ion nitriding treatment. The fretting wear tests were carried out under laboratory conditions. The wear mechanisms of nitrided and untreated specimens which rubbed with GCr15 steel were investigated under dry friction and oil lubrication, respectively. It is found out that the predominant wear mechanisms of nitrided specimens under dry friction are slight abrasive wear and adhesive wear, whereas under oil lubrication, it is mainly spalling. The wear mechanisms of untreated specimens under dry friction are identified as adhesive wear and oxidative wear, while it is mainly abrasive wear under oil lubrication.
Research of intergranular corrosion properties of heat affected zone for HR3C steel after aging treatment
Authors: Xinmei Li , Zhongwen Zhang , Nan Li , Baoshuai Du , Xiulian Li , Yuzhong Wei
Published: August 2019

The intergranular corrosion susceptibility of heat affeceed zone(HAZ) for HR3C steel after aging at 600°C was investigated using electrochemical double-loop potentiokinetic reactivation. Experimental results show that HAZ has intergranular corrosion susceptibility after aging at 600°C. At the initial stage precipition of M23C6 along grain boundaries occurs rapidly, which leads to formation of Cr-depleted in the grain boundary and the increase of intergranular corrosion susceptibility. With the increase of aging time, the Ra value of HAZ rapidly increase. Intergranular corrosion of HAZ after aging occur due to the precipitation of M23C6 along grain boundaries, not only the precipitation of M23C6 along grain boundaries caused poor Cr, but the precipitation of M23C6 inside the grains also results in the formation of Cr-depleted zone and subsequent corrosion.
Ablation morphology and redistribution layer of gold films with different substrates irradiated by femtosecond laser pulse
Authors: Xu Zhijie
Published: August 2019

Gold micro/nanostructure is of great significance in many scientific and engineering fields for its unique optical, electrical and thermal properties. Gold film deposited through electron beam (EB) evaporation is a suitable raw material for the fabrication of gold micro/nanostructure. Femtosecond laser directing is one of the reported methods for high-efficiency and low-cost micro/nanofabrication. We present a comparative study of gold film ablation with different substrates (Si, SiO2, ZnO) under the irradiation of single femtosecond Gaussian pulse. The morphologies of ablation areas and redistribution layers are investigated by many characterization methods, such as scanning electron microscopy (SEM) and atomic force microscopy (AFM). In general, the ablation morphology and the ablation hole are mainly affected by the bandgap. Besides, the heat conductivity is the main factor affecting the width and height of the redistribution layer.
Study on Friction Properties of WC Particle-Reinforced High-Chromium Iron-Based Powder Metallurgy Materials
Authors: Wei Tao , Ma Mengyang , Li Ziyang , Qin Shunshun , Wang Chengzong , Li Xiaoqiang
Published: August 2019

High-performance powder metallurgy high-chromium iron-based alloy reinforced by nano-WC particles were prepared by high-energy ball milling combined with hot-press sintering. The effects of different temperatures of hot-press sintering and contents of WC reinforced phase on the friction and wear properties of the materials were studied by using the M-2000 Friction and Wear Tester under dry condition. The results show that the wear property of the material increases first, and then decreases with the growth of temperature of sintering and contents of reinforced phase. The alloy has the best wear property sintered at 1050 °C with 5wt.% WC reinforced phase. By comparing with NbC reinforced phase with similar mass fraction at 5%, finding that WC particles have more significant effect on reinforcing the wear
Research on Dielectric Loss Angle of Capacitive Equipment Based on Blackman Window Improved FFT
Authors: Cai Hanxian , Zheng Fangqing , Lu Xuerong
Published: August 2019

According to the fact that the dielectric loss angle of capacitive equipment is mainly determined by the phase difference between its terminal voltage and leakage current, cutting short the voltage and current signals by Blackman window, and correcting the spectrum of voltage and current signals by three-spectral line interpolation method and 7-order polynomial fitting technique, a simple and practical frequency correction formula and a formula for calculating dielectric loss angle based on improved FFT are given. The results of simulation and measurement show that the spectrum correction method presented in this paper is effective under harmonic interference and frequency fluctuation of power grid, and the measurement results of dielectric loss angle delta are accurate and stable.
Study on the stirred blade mounting height-to-liquid level-ratio related to the law of flow field inside the stirred reactor
Authors: Cheng Lei , Zhang Zhenwei , Zhao Xinyu , Lin Qia
Published: August 2019

To figure out the law of the height of stirred blade installed inside the reactor affect the fluid inside, this article used CFD to Numerical simulation of the liquid filled area of the stirred reactor, then obtain the distribution of the liquid velocity field inside the reactor.Through the comparison of calculation. Consider the weak area of stirred mainly concentrated above the stirred blade, when stirred blade were installed at the stirred blade mounting height-to-liquid level-ratio reach to 40%, ti means the mixing level reach maximum, according to the calculation the average turbulence kinetic energy is 0.003407-40 0.002994-45. and standard deviation of turbulence kinetic energy is able to stable between 0.001503-40 to 0.001275-45.
Fuel Consumption Model of Aircraft in Descent Stage Based on DBN
Authors: Wu Zhentao , Li Xueren , Du Jun
Published: August 2019

Due to the pressures of the current ecological environment and the rise of fuel prices, it is necessary to calculate the fuel volume of aircraft accurately. In order to calculate the fuel consumption of a flight, the key is to establish an accurate fuel consumption model. In the process of descent, because the environment around the aircraft changes dramatically, compared with other stages, the fuel consumption factors affecting the descent stage will be more. But at present, the domestic fuel consumption model for aircraft descent stage is not accurate enough. To solve this problem, a method of building fuel consumption model in aircraft descent stage based on flight data using Deep Belief Network (DBN) is proposed. Firstly, the parameters related to fuel consumption are selected from the flight data, then the correlation between each parameter and fuel consumption rate is calculated by mutual information algorithm, and finally the parameters with the highest correlation are selected for model training. Compared with the traditional BP neural network and Echo State Network (ESN), the accuracy has been greatly improved.
Research and Design of proximity fuze Scheme Based on 24GHz Radar Sensor
Authors: Tian Zheng-gang , Liu Cheng-an
Published: August 2019

Modern warfare requires more and more adaptability to the environment. The proximity fuze based on microwave radar sensor has high anti-interference performance, which can achieve accurate hit and high efficiency damage in the complex environment. The microwave radar sensor has the characteristics of strong anti-interference ability, high precision of ranging and high speed measurement, and can accurately extract target information. This paper mainly introduces a design and implementation scheme of proximity fuze based on 24GHz microwave radar. With a small spatial structure and high integration, combined with the Doppler principle, antenna scanning technology and FFT system software design, the detonation range of the lowest 0.5m and 30m is determined effectively and reliably with a low false alarm probability.
Design of a High Resolution TDC Based on Multi-channel
Authors: Zhang Qingsong , Xu Guanghui , Li Na
Published: August 2019

In this paper, a high precision time digital converter (TDC) system is designed based on Xilinx 7 series FPGA chip, which includes fine time measurement module, logic control module, rough count module and display module. The key point of FPGA TDC design is that there are a large number of delay units in the underlying hardware resources with stable delay. A delay chain consisting of 64 fast carry chains (CARRY4) is constructed by using the CARRY4 module inherent in the chip. In addition, the code density method is used to solve the nonlinear problem of internal special carry chain delay unit, effectively eliminate the error caused by wiring path, and reduce the integral nonlinear and differential nonlinear error. The experimental results show that the code density method can accurately reflect the distribution of delay time.
A DTN Routing Scheme for LEO Satellites Topology
Authors: Qi YaoWen , Yang Li , Chen ShuangJian
Published: August 2019

In delay/disruption-tolerant satellite networks, the existing routing algorithms have problems of long transmission delay, high packet loss rate, excessive network overhead and other issues. In the view of these shortcomings, an improved contact graph routing algorithm, ICGR, is proposed in this paper. Firstly, the impact of queuing delay is considered by defining a queue factor and proposing a queue scheduling mechanism in routing calculation; secondly, the effects of contact’s remaining capacity are taken into account to avoid the selected path being unable to forward the messages; thirdly, routing update mechanism is optimized by designing a message path update factor to strike a balance between real-time updates of transmission and resource consumption; finally, a LEO satellite network simulation platform is built with OPNET to verify the performance of this algorithm. Simulation results show that the ICGR, compared with the ED and CGR algorithm, has advantage in packet delivery rate, average transmission delay and network overhead.
Research on the Key Technology of Safety Protection in Application Environment of Blockchain
Authors: Zhang Hua , Wang Jiong , Xu Ge , Ruan Zhiqiang
Published: August 2019

This paper analyzes the current situation of blockchain application security. Then, makes a concrete analysis on the problems existing in the application safety of blockchain, including the attack of consensus algorithm, the leakage of privacy, and the programming vulnerability of blockchain and hash collisions. Then it introduces in detail the three key technologies of security protection under the blockchain application environment, P2P network technology, asymmetric encryption technology and consensus mechanism technology. In order to make more relevant people know more about the key technologies of safety protection in the application environment of blockchain.
A Method of Stable Extended Kalman filter
Authors: Peng Gu , Kai Wang , Shicang Zhang
Published: August 2019

The extend kalman filter provides an stability solution to the approximate nonlinear-Gaussian filter problem. Due to the limitation of the word length of the processor, the rounding errors is easy to occur in the calculation, which causes the covariance matrix to lose its positive definite and convergence. In order to solve this problem, The proposed stable extended kalman filter (SEKF) method is applied to the problem of non-positive and divergence in recursive filter. This method introduces the matrix decomposition and constructs a covariance square root adaptive filter which is used to solve the numerical stability problem of the extend kalman filter. Experimental results show that SEKF can effectively guarantee symmetric positive definite in recursive calculation, and perform remarkably better than EKF algorithm.
MI-based optimal jamming waveform design
Authors: Chen Xu , Wang Bin , Yu Hao , Xin Fengming , Wang Jinkuan
Published: August 2019

In order to improve the estimation performance of radar system, previous studies on radar waveform design mostly focused on maximizing the mutual information between the target and the echo to design the transmitted waveform. However, these studies neglect the existence of jammer in the actual electromagnetic environment, so this paper introduces a jammer to design the corresponding jamming waveforms according to whether there are signal-related clutter or not, which weakens the estimation performance of radar system. Simulation results show that the energy allocation strategies of the two jamming waveforms are different.
Design of Ultrasonic Guided Waves Signal Generator Based on FPGA
Authors: Yang Jie , Qu Zhigang
Published: August 2019

Ultrasonic guided waves have been widely concerned in recent years due to their long transmission distance, wide coverage, and no influence on production. In the future, they have great potential to become a new descaling method widely used in industry. Piezoelectric ultrasonic transducer is an actuator based on ultrasonic guided waves descaling system, which requires high-precision signal source to drive. This paper designs a high-precision signal generator based on FPGA. The DDS signal generator based on FPGA and the ultrasonic guided waves descaling system based on FPGA are introduced. Through theoretical analysis and experimental verification, the test results show that the FPGA-based signal generator can generate the required excitation signal, and the FPGA-based ultrasonic guided waves descaling system proposes a new descaling method for the industry.
The design of Handheld Stabilizer with Follow Focus Function
Authors: Liao Yinhan , Song Shuxiang , Li Rui , Lu Lifen , Xia Haiying
Published: August 2019

In this paper, we design a follow focus system, which can be integrated with a handheld stabilizer. The follow focus system of the handheld stabilizer includes the following steps: establishing communication relationship, signal input, signal transmission, focusing control and adjusting camera parameters. The follow focus system solves the problem that the parameters of the follow focus and the platform need to be adjusted by both hands. It optimizes the problem of wire winding in stabilizer, while it combined with the follow focus wired control. It indirectly shortens the response delay of the wireless follow focus by using the internal wiring of the stabilizer. It achieves not only adjusting the camera parameters, but also stabilizing the follow focus of the real-time camera.
Design of sparse cosine modulated filter banks based on Hopfield neural network
Authors: Xu Wei , Gao Xin , Zhao Jiaxiang
Published: August 2019

Cosine modulated filter bank (CMFB) is the most basic and important module in multi-rate signal processing system. Sparse FIR linear-phase CMFB can not only reduce the complexity of hardware design, but also ensure good performance. In this paper, a new design method of CMFB is proposed. First, the set of sparse coefficients of the prototype filter is found by using the orthogonal matching pursuit (OMP) algorithm. Then the Hopfield neural network (HNN) is employed to optimize the non-zero coefficients. The analytical and simulation results demonstrate that the new approach not only ensures that the sparse CMFBs satisfy near perfect reconstruction (NPR), but also improves the efficiency of hardware operation.
I3D-LSTM: A New Model for Human Action Recognition
Authors: Wang Xianyuan , Miao Zhenjiang , Zhang Ruyi , Hao Shanshan
Published: August 2019

Action recognition has already been a heated research topic recently, which attempts to classify different human actions in videos. The current main-stream methods generally utilize ImageNet-pretrained model as features extractor, however it’s not the optimal choice to pretrain a model for classifying videos on a huge still image dataset. What’s more, very few works notice that 3D convolution neural network(3D CNN) is better for low-level spatial-temporal features extraction while recurrent neural network(RNN) is better for modelling high-level temporal feature sequences. Consequently, a novel model is proposed in our work to address the two problems mentioned above. First, we pretrain 3D CNN model on huge video action recognition dataset Kinetics to improve generality of the model. And then long short term memory(LSTM) is introduced to model the high-level temporal features produced by the Kinetics-pretrained 3D CNN model. Our experiments results show that the Kinetics-pretrained model can generally outperform ImageNet-pretrained model. And our proposed network finally achieve leading performance on UCF-101 dataset.
A Sea Wave Surge Base Alignment Test Device Based on the EtherCAT Fieldbus
Authors: An Kangkang , Huang JinXin , Li ChongLing
Published: August 2019

A sea wave surge base alignment test device consisting of a linear motion guide rail, a stewart platform, a rotating mechanism, a cantilever beam and an electronic control system based on an EtherCAT fieldbus is designed. The linear motion guide and the stewart platform provide the seven movement dimensions for the whole device. the rotating mechanism, the cantilever beam and the linear motion guide widen the movement dimension and amplitude of the device.the EherCAT fieldbus effectively satisfies the real-time, synchronization and accuracy of the whole device. the whole system effectively satisfies the requirements of multi-degree, large amplitude, low frequency, large acceleration combined superimposed rocking motion and simulation motion in the sea wave surge simulation motion.
Realizing High-order Bessel Vortex Beams with High-level Phase Holograms
Authors: Zhai Zhongsheng , Huang Jiaojie , Cheng Zhuang , Lv Qinghua , Wang Xuanze
Published: August 2019

High-order Bessel beams are widely used in laser processing and precision measurement. For the realization of high-order Bessel beams, a spatial light modulator is used to load the high-order phase hologram instead of the real spiral phase plate and the axicon. The distribution of light field in two modes of axicon combination and phase superposition is analyzed theoretically. The beam modulation in two modes is designed and compared experimentally. The results show that the modulation effect of the phase superposition method is better than that of the axicon combination method. Meanwhile, the operation is flexible and the manufacture errors can be reduced. It is an effective method for realizing high-order Bessel beams.
A General Parameterized High Precision Finite Element Modelling Method of Three-dimensional Helical Gear
Authors: Liu Yanping , Zhao Yongqiang , Liu Ming , Sun Xiaoyu
Published: August 2019

In order to be able to perform an LTCA with satisfactory accuracy and time consuming, a parameterized approach to establishing a high-precision three-dimension (3D) finite element model (FEM) of involute spur/helical gears is proposed. The enveloping theory and dentiform normal method are applied to deduce the mathematical representations of the root transit curve as well as the involute tooth profile of the external gear in the transverse plane based on the manufacturing process and an accurate description of the cutter. The bottom-up modelling method is used to build the finite element model of the helical gear directly without create the geometry model in advance. A computer program is developed to establish 3D helical gear finite element model of any parameters and mesh density automatically. Computerized tooth contact analysis of load sharing and con-tact pressure as well as transmission error and mesh stiffness are also simulated and calculated. This methodology can also use to create other types of involute gears, such as involute helical gears with crossed axes or spiral bevel gears.
Research on multi-targets real-time ballistic recognition method based on movement multiple feature correlation
Authors: Yang Zengxue , He Lifeng , Wang Xiaohua , Lei Hao
Published: August 2019

In the optical measurement of burst multi-targets such as the rocket, missile, bullet and so on, in order to solve the poor real-time reliability problem of the multi-targets ballistic recognition caused by the invalid ballistic recognition algorithm variable and less movement feature quantity, a multi-targets ballistic recognition method based on movement multiple feature correlation has been proposed, and the mathematical model algorithm and multi-targets real-time ballistic recognition strategy has been established at the same time. It has been proved that the method can improve the adaptability, real-time performance and reliability of multi-targets real-time ballistic recognition, to provide technical support to real-time multi-targets optical measurement and processing.
Acoustic Effects of Underwater Plasma Pulsed Sound Source under Different Electrical Parameters
Authors: Chen Zhenyang , Zhang Xiaobing , Yan Bing
Published: August 2019

Methods of pulse discharge in water were studied under different voltage and conductivity parameters. The voltage and current data in the experiment were collected and analyzed. Then the mechanism of the two discharge modes was briefly discussed (the initial mechanism of the corona mode is still unclear compared to the thermal process mechanism of the arc mode). Finally, two kinds of discharge methods were compared and analyzed from the aspects of experimental phenomena, production mechanism and application prospects. The experiment found that the acoustic effect of corona discharge in water under large solution conductivity is obvious, which provides a new idea for the design of underwater plasma sound source.
Design of Electric-Take Ring for Microcomputer Relay Protection Device
Authors: Xiao Wubing , Ling Pengpeng , Sha Wen
Published: August 2019

A miniaturized electric-taking ring used in microcomputer relay protection device is designed in this paper, which can obtain electric energy from the measured circuit and provide stable power supply for the protection device. The test results show that the ring is suitable for microcomputer relay protection device, low cost, safe and stable, and solves the difficult problem of equipment power supply in box environments.
Complete subdomain model for radial-flux slotted PM machines with toroidal windings accounting for the iron-part
Authors: Wu Jiang , Wen Bin , Zhang Yinyou , Zhang Qi
Published: August 2019

Most subdomain models do not solve the magnetic vector potential in the iron part of the machine, this paper proposes a complete subdomain model for (PM) machines with toroidal windings and mainly solves the magnetic vector potential in iron part. The proposed model can accurately predict the field distribution under load or no-load conditions. The electromagnetic parameters of the motor (including magnetic flux density, back-emf, electromagnetic torque, and cogging torque) are calculated using the proposed analytical model, and validated by a FEM model. This paper presents a technique to handle with the stator of machines with outer teeth and the very specific techniques to solve the magnetic field in the iron part.
Research on Test Method of Communication Interface Converter Based on Simulated Field Conditions
Authors: Yan Du , Long Wang Zhe , Liang Guo , Xia Zhu Hong , Jie Yang
Published: August 2019

This paper used the wind pressure, sealed water circulation system, wireless attenuator and interface state analog circuit to establishes simulated field operation condition of “Multi-meter unification”. A test method of communication interface converters and concentrator for “Multi-meter unification” is proposed based on the experimental environment, which including function test, interface performance test and compatibility test, and to ensure the stable operation of the field communication interface converter and concentrator.
The Spectrum Allocation Technology Based on Hybrid Particle Swarm Optimization in Cognitive Communication
Authors: Zhang Wenhe , Huang Guoce , Wang Guisheng , Wang YE
Published: August 2019

With the increase of the number of communication users, the high frequency (HF) communication resources are scarce and more precious. Aiming at the problem of frequency allocation in cognitive HF communication, this paper transforms it into the problem of maximizing network revenue, and solves the problem by using particle swarm optimization algorithm based on natural selection (NSPSO), which can get better solution in a short time. The experimental results show that the proposed algorithm is better than the conventional particle swarm optimization (PSO) and genetic algorithm (GA) in the effectiveness and speed.
Intelligent Home Communication Design Based on Home Computer
Authors: Ling Pengpeng , Xiao Wubing , Sha Wen
Published: August 2019

Along with the continuous development of computer technology, the increase in the number of computer popularization, especially the microcomputer used in the home environment, has brought a lot of convenience to human life. In recent years, intelligent home has developed rapidly, and intelligent home environment provided higher spiritual material experience for users. However, in the remote control of smart homes, most of them use network communication chips such as 3G and 4G, which wastes computer resources in the home environment. Therefore, this paper proposes an intelligent home design based on home computer, hoping to reduce the development cost of existing smart home technology and eventually accelerate the popularization of smart home.
Design and implementation of EEMD-assisted ICA joint denoising scheme for ECG signals
Authors: Chen Hanlin , Zhao Cheng , Yin Jingyi
Published: August 2019

Independent Component Analysis (ICA) algorithm is a signal processing method for solving blind source separation(BSS) problem, which can remove noises in observed signals and obtain original signals. This paper designs and implements an EEMD-assisted ICA joint denoising scheme for ECG signals. Firstly, Ensemble Empirical Mode Decomposition (EEMD) is used to perform noise-assisted data analysis on ECG signals, completing pre-denoising of ECG signals and pre-processing for subsequent ICA analysis. Next, to more thoroughly remove noises in ECG signals, ICA separates independent components from pre-denoised signals. Finally, signal reconstruction restores original ECG signals, so as to realize ECG denoising. Experimental results show that the scheme can effectively remove common noises, and get clean ECG signals, which lay a good foundation for accurate diagnosis of heart patients.
A Multifunctional Terminal Hardware Design for Teaching Assistant
Authors: Chang Qing , Gao Yushan , Guo Lin , Yang Zehua , Chang Cun
Published: August 2019

An intelligent handheld terminal for campus was designed to meet the teaching management requirements under the new education situation. This system is composed of fingerprint identification module, wireless communication module, LCD touch screen module and embedded system. So, it can achieve multiple functions. Specifically, we design the hardware schematic diagram and PCB, then devise driver and transplant FreeRTOS operating system according to the working characteristic of each module. The communication protocol between the handheld terminal and the host computer is designed to complete the process of collecting fingerprint attendance and classroom test data and then transmitting those data wirelessly to the host computer. This system will be helpful to improve the campus service and teaching quality.
Analysis of Parachute Recovery Process for UAV based on Launch Rocket
Authors: Li Kai , Chen Gang
Published: August 2019

Taking a certain type of UAV as an object of study, this paper analyses the UAV emergency parachute recovery system based on parachute rocket. The dynamics and kinematics models of the parachute and UAV during recycling process are built respectively. The simulation results of recovery motion under windless conditions are given and the changes of attitude speed and other parameters of UAV in different stages of recovery process are analyzed. On this basis, the related factors affecting the safe landing of UAV are studied, which provides a reference for UAV to choose the time for opening the umbrella.
KS-FALL: Indoor Human Fall Detection Method Under 5GHz Wireless Signals
Authors: Hao Zhanjun , Duan Yu , Dang Xiaochao , Xu Hongwen
Published: August 2019

In modern society, it has become the main threat to the elderly fall’s health or even death in the elderly. The real-time and reliable fall detection system can save the fall and hurt the elderly in time. In this paper, a human fall detection method KS-FALL based on Channel State Information and in 5G environment is proposed. KS-FALL uses Atheros commercial NIC equipment to map the amplitude information in the wireless signal to the human body’s fall action, and does not require the user to wear any equipment. Compared with the traditional 2.4 GHz signal, the 5 GHz signal provides richer sub-carrier frequency domain information, which better reflects the relationship between human motion and wireless signals, thereby more effectively distinguishing and recognizing walking, squatting, falling, etc. action, filter the environmental interference through powerful denoising method, use K-means to cluster different action data, combine SVM classifier to construct fine-grained offline fingerprint database, and use SoftMax regression model to correct SVM classification in real-time detection stage. And real-time test in two different scenarios, and the detection accuracy of the fall reached 92.3%, realizing the device-free, non-invasive, high-precision human fall detection.
Research on On-line Dynamic Testing and Operation Time Control Method for Critical Vibration Zone of Water Turbine Generator Set
Authors: Wen Xiankui , Shen Chunhe , Su Li , Mao Cheng
Published: August 2019

At present, there is no relevant definition and requirement for the critical vibration zone of hydropower units. By summarizing and analyzing the operation stability of the unit, the definition of critical vibration zone is given. An on-line dynamic testing method for vibration region based on comprehensive stability index of hydropower units is proposed. For the two methods of dynamic on-line testing and manual setting in critical vibration zone, the operating time control functions are given respectively to ensure the safe operation of the unit and to improve the operation range and adjustability of the unit.
Research on EMI Radiation Source Model Based on Battlefield EMC Prediction Analysis
Authors: Li Yong , Chen Dong , Zhang Xiao Long
Published: August 2019

In complex electromagnetic environment, using modeling and simulation to predict and analyze battlefield EMC has become the main means. Based on the analysis of the characteristics of the transmitter, such as fundamental wave emission, harmonic emission, nonharmonic emission, intermodulation and intermodulation interference, the fundamental wave emission model, harmonic emission model, non-harmonic emission model, intermodulation interference and intermodulation interference model are constructed for the prediction and analysis of EMI Radiation Source, and the primary problem of battlefield EMC modeling and simulation prediction is solved.
Research on Fault-Environment Association Rules of Distribution Network Based on Improved Apriori Algorithm
Authors: Xiao Maoran , Sun Yuanyuan , Li Kejun
Published: August 2019

As the urban power grids gradually enter the high reliability level, the distribution network risk early warning becomes the key to further improve the reliability level. Distribution network faults have the characteristics of strong randomness and weak causality, and conventional methods are difficult to find their laws. The idea of data mining is introduced in this paper. Based on the analysis of various types of fault data, the improved Apriori algorithm is used to mine the strong correlation rules of various influencing factors in the distribution network, and the fault-environment pattern recognition library of distribution network is established to lay the foundation for the early warning of distribution network operation risk.
Lightning Strike Risk Assessment and Lightning Protection Approach for Highway Electromechanical Equipment
Authors: Wang Enshi , Huang Bihui
Published: August 2019

To ensure the normal operation of highway electromechanical equipment and avoid lightning disasters, it is necessary to design lightning protection devices in the highway electromechanical system. However, due to factors such as the technical level and life limit of the lightning protection device, some lightning protection devices are over-aged, and often fail, resulting in frequent lightning damage to the electromechanical system equipment. In this study, the design and comprehensive evaluation of the current lightning protection devices was carried out to ensure that they can work normally. Safety analysis was performed on the electromechanical system lightning protection device to ensure the safe and stable operation of the electromechanical system.
Traffic Safety Evaluation Approach for Reconstructed Freeway Medium Strip Opening Area
Authors: Zhou Jiacai
Published: August 2019

The remaining of the medium strip of the freeway in reconstruction and widening project reduces the cost of renovation, however brings potential driving risks. In this study, the characteristics of traffic flow changes caused by the opening of the medium strip were analyzed. The safety of the opening length of the medium strip was evaluated based on the interweaving and conflicting driving behavior characteristics, and the opening length of the interweaving area of the medium strip was calculated. In addition, the location of the exit traffic sign was advised for this new traffic flow characteristic. Appropriate opening length of the medium strip and the optimized traffic signs can effectively guide drivers to enter and exit the closed area of the central separation zone safely and comfortably.
Spatial Differentiation of Land Reclamation in Shandong Province since the 21st Century
Authors: Wang Xiaowei
Published: August 2019

Cultivated land refers to the land on which crops are grown, which are the basic resources and conditions for human survival. This paper uses the data of Shandong Statistical Yearbook (2001-2018) to study the spatial and temporal distribution pattern of cultivated land resources in Shandong Province by using GIS technology. The results show that the area of cultivated land between 2000 and 2016 is generally increasing, which is divided into attenuation and recovery. After adjusting the three stages, the cultivated land area has a downward trend after 2012, which is worthy of attention. From the perspective of the characteristics of the cultivated land resources, the cultivated land resources of the province are characterized by the lack of more than the east and the east, and the growth of the land reclamation rate is expanding to the east. From the perspective of the overall distribution of cultivated land resources, the average annual growth rate of cultivated land area in Shandong Province during the period from 2000 to 2016 was 0.89%, the average annual growth rate in Luzhongnan area was slightly faster at 1.07%, and the highest rate of land reclamation in northwestern Shandong was 60.96%, the most extensive cultivated area is Linyi City, the largest land reclamation rate is Liaocheng, the land reclamation rate is 67.50%, and about 2/3 of the land is cultivated land.
Adaptive sliding mode control for multi-UAV systems with parametric uncertainties
Authors: Yu Liang , Liu Yongchun , Lin Da , Han Qiang
Published: August 2019

This paper proposes a parametric uncertain adaptive sliding mode control method for multi-UAVs formation. The tracking effect is well under the condition of uncertain inertial matrix parameters and external interference. An adaptive law is designed to estimate the inertial matrix parameters of each UAV in the formation on-line, and the estimated values are used in the sliding mode controllers, which guarantee that the tracking error is uniformly asymptotically converged to zero. Then the adaptive sliding mode control the stability performance of is proved by Lyapunov stability theory. Finally, simulation illustrated that under the uncertain conditions and external disturbances in the system, the method can achieve the Multi-UAVs formation with a stable attitude and speed synchronization.
Simulation comparisons by three strategies of control on Ships’ fin stabilizer control system
Authors: Song Yang , Lv Zhenwang , Zhang Yuqiang , Wang Zixin
Published: August 2019

Reducing the ship rolling motion is an important subject of the ship motion control. And the fin stabilizer is one of the most effective ship stabilizers, which plays an important role in improving the ship seaworthiness, giving a longer life for the ship, ensuring the equipments on the ship working better and making the ship members feel comfortable, advance battle effectiveness of the naval ship. Since the ship rolling motion has the characters of the nonlinearity and randomicity. The building of the mathematic model is difficult. Therefore, the method, that the exact mathematic model is not needed priorly, will be suitable for the control system. In the strict sense, the PID and MFLAC are in accord with these characters. Simulations are given for the fin stabilizer’s control system with three different control methods: Proportion Integration Differentiation (PID), Model-Free Learning Adaptive Control (MFLAC) and the improved MFLAC based on Multi-Innovation (MI-MFLAC). The principles of the three methods are introduced and the advantages and disadvantages of the three methods are represented. The satisfied control effects are achieved with the latter two control strategies.
TRANSIENT BEHAVIOR IMPROVEMENT OF ITERATIVE LEARNING CONTROL SYSTEM BASED ON PSEUDOSPECTRUM METHOD
Authors: Liu Bin , Li Jiming
Published: August 2019

Robust monotonic convergence (RMC) should be obtained when designing ILC (Iterative learning control) system. But it may cause convergence rate becoming slower. In order to maintain stability of control system, transient growth is often limited within a certain range, which is one of the most properties of transient behaviors. Pseudospectral of the system transfer matrix is introduced to predict the transient growth of ILC system. At the same time, asymptotic performance can be improved if the transient growth is kept small. Under this case, the convergence rate will also be speeded up. The simulation demonstrates the effective of new method for designing ILC system.
Research on All Terrain Tracking Platform Based on Inertial Navigation
Authors: Yong Gan , Qiufeng Zhang , Siliang Pan , Xu Meng , Weiqiang Zhu
Published: August 2019

In order to solve the dangerous situation that search and rescue personnel are not suitable for direct internal search and rescue in harsh closed environment without GPS signals, an all-terrain trajectory tracking platform based on inertial navigation is designed and studied. An autonomous navigation system is composed of low cost, low power consumption, small size MEMS inertial elements, which do not depend on external information and radiate energy. Kalman filter is used to fuse the data of accelerometer, gyroscope and magnetometer and output stable and reliable azimuth angle. By combining the Hexapod joint structure with the roller track structure, the multi-environment and all-terrain machine traveling is realized. The experimental results show that the three-dimensional and two-dimensional space trajectories can be clearly drawn in outdoor complex environment. In indoor environment, the platform achieves positioning error within 5 meters, deviation is not more than 10 cm, and draws a map that conforms to the platform trajectory. The development of the platform provides a powerful help for exploration work.
Optimization of traditional Snort intrusion detection system
Authors: Zhang Dongyan , Wang Shuo
Published: August 2019

With the rapid development of the Internet, the following network security issues are increasingly prominent and the increasing number of network attacks has also attracted the attention of more professionals. Network attacks are generally divided into operation attack, spoofing attack, flooding attack, redirection and so on. In order to ensure the security of computer system, intrusion detection system is designed, and people pay more and more attention to it. Firewall as the first security gate to maintain network security, intrusion detection system is undoubtedly the second security gate after the firewall. Snort intrusion detection system is a typical application of intrusion detection system. In addition, Snort is a real-time traffic analysis system that can capture and analyze packets on the network according to defined rules. However, with the continuous increase of data volume and the emergence of big data, the pattern library of Snort intrusion detection system also expands correspondingly, leading to the decrease of detection efficiency. DPDK(Data Plane Development Kit) adopts polling method to realize data packet processing, which saves CPU interrupt time, memory copy time, and provides a simple and efficient data packet processing method to the application layer, making the development of network applications more convenient. How to improve the efficiency of Snort intrusion detection system with the advantage of DPDK’s high-performance packet processing is the research focus of this paper.
Power Precise Load Shedding Control Strategy Considering User Demand Response Clustering
Authors: Li Qin , Xu Zhiqiang , Zhang HuiFang , Liu Yi , Lu Jun , Hu Zesheng
Published: August 2019

Load shedding control is one of the key technologies for stable operation and efficiency optimization control of power system. Aiming at optimized load overcut rate optimization problem for second/minute level precision load shedding efficiency, a precise load shedding control method based on user demand response clustering is proposed. Firstly, based on the analysis of the characteristics of the precise load control system, the authors construct the optimal mathematical model of the precision load shedding control strategy with minimum load overcut rate using the user load clustering. Secondly, the particle swarm algorithm is used to achieve the minimum load overcut rate control strategy model. Finally, through the analysis of the example, the proposed method can reduce the 30% load over-cut rate and the load over-cut rate volatility compared with the traditional method, and verify the effectiveness of the proposed method.
Design and Implementation of Intelligent Robot Walking Control System Based on DSP
Authors: Junsong Chen
Published: August 2019

In recent years, the aging of the population and the acceleration of urbanization have led to a decrease in labor force, an increase in production costs and a decrease in labor productivity. In order to solve these problems, the degree of mechanical automation is bound to increase. This paper has completed the design and development of the automatic walking robot control system, mainly to realize the functions of visual navigation and walking control of the control system. The experiments prove that the vision navigation system of the automatic walking robot can provide the walking control system with direction identification and identification information of the ridge and furrow extension paths between fields. The designed walking control system can call the motor driver to realize the forward, backward, left forward, right forward, left backward and right backward rotation of the control object according to the path information. After experimental debugging, the automatic walking robot can move according to the direction of the identification image, which greatly improves the real-time and intelligent level of the automatic walking robot.
Research on Security Problems and Defense Strategies of Power Communication Networks
Authors: Feng Chi , Chen Qingping , Cai Xiang , Yang Xianjie , Li Zhou , Chen Shan , Wu Lisha , Hu Zhongkun
Published: August 2019

The development direction of power systems is automation, networking and intelligence. The intranet and extranet dual network operation modes have been applied in the power system, but there are still many problems. Due to the continuous expansion of the power communication network, massive communication data is continuously generated in daily operation. At the same time, the means of attack on the power system communication network has evolved, seriously threatening the security of the power communication network. Therefore, it is necessary to further increase the research on the security and protection of power communication networks. This paper discusses the current status of China’s power communication network, analyzes the main factors affecting the security of power communication networks and the security problems of power communication networks. Finally, corresponding protective measures are given to provide reference for improving the security and stability of power communication networks.