bluuebunny/crossref_metadata_2025_split huggingface dataset:
Optimization design of gas sand deflector for reverse circulation drilling
Authors: Liu Biao , Wang Lei , Chen Shukai , Zhang Dongsen , Wang Caibao , Wang Hao , Zhou Yufan 
Published: September 2020

Abstract
Gas reverse circulation drilling which has a wide application prospect in complex strata of deep and ultra-deep wells can effectively improve drilling speed, protect the environment, reduce costs, and reduce downhole accidents, but its string structure is different from that of conventional drilling. In this paper, the design of integral and splitter head-in to side-out rotary sand deflecting device consists of rotating inner tube and non-rotating outer deflecting chamber, so that it can be effectively connected to the double-wall drill pipe system to ensure the normal sand deflecting of the gas reverse circulation drilling system. At the same time, the test well was verified and analyzed, and the sand-carrying efficiency was close to 92.53%. After drilling, there was no sand-settling at the bottom of the well. The average carrying rock diameter is about 10-15mm, and the maximum can be up to 30-40mm, indicating that the top-injection side-exit gas sand guide can be used for gas reverse-circulation drilling.
The system design based on long-wave uncooled infrared detector
Authors: Feng Shuyi , Xie Baorong , Liu Yanli , Wang Yang , Mu Wentao 
Published: September 2020

Abstract
According to the requirement of high-definition surveillance of the status of space targets in low illuminance, a high SNR (Signal to Noise Ratio) uncooled long-wave infrared system is designed. Based on the detector of UL04371 with 640 × 480 array, the system scheme, acquisition system and real-time image processing algorithms are realized. On the basis of system implementation, the paper mainly focuses on how to reduce the noises from the aspect of hardware circuits and how to realize the real-time processing in the way of specified infrared image algorithms. Finally, the paper gives the test result which shows that the system has achieved a relatively good SNR characteristic with the average NETD (Noise Equivalent Temperature Difference) value of 220mK under the condition of the integration time of 64us and the radiation of 300K black body.
Analysis and optimization of electromagnetic scattering characteristics of two-dimensional metal airfoil covered with metamaterial
Authors: Liu Ji , Yan Zhaowen , Ji Jinzu , Chang Qi , Song Hang 
Published: September 2020

Abstract
Airfoil is one of the strong scattering sources of aircraft, so it is of great significance to study the stealth characteristics of airfoil for the reduction of the radar cross section of the whole aircraft. As is known, the airfoil of aircraft is the main component that generates lift. Shaping the airfoil will reduce the aerodynamic performance of the aircraft. However, the emergence of metamaterials allows aircraft designers to achieve a good balance between stealth and aerodynamics. Considering the high cost of stealth test, numerical simulation is proposed to guide the design of metamaterial stealth. Then, the bistatic radar cross section (RCS) of airfoil covered with metamaterial is researched in this paper. We employ the 2-D auxiliary differential equation finite-difference time-domain (ADE-FDTD) to simulate the airfoil’s stealth characteristics. The two-dimensional situation can be regarded as a special approximate when electromagnetic waves are perpendicularly incident on the three-dimensional infinitely long airfoil. The tuning parameters including coating thickness, Drude frequency and collision frequency are considered on the airfoil’s bistatic RCS. The calculation program verified its correctness by simulating the perfect lens characteristics of electromagnetic waves propagating in the metamaterial plate. The numerical experiments show that the meta-material Drude frequency and collision frequency mechanism are more complicated than the coating thickness. The dual-station RCS increases at some angles and decreases at other angles than metal airfoils. But by choosing appropriate metamaterial parameters, airfoils with excellent stealth effect can be obtained.
Simulation analysis of autofretted barrel strength based on ABAQUS
Authors: Yang Yuliang , Sun Yezun , Li Yue 
Published: September 2020

Abstract
Autofretted technology is used generally by high-pressure guns to enhance the strength of barrels. Mechanical properties of the autofretted barrel were studied based on the finite element software ABAQUS. For the open autofretted process, a simulation model of gun barrel was established and its accuracy was verified by comparing the simulation results with theoretical results. Various stress of autofretted gun in the firing process was simulated, and the best autofretted pressure was found. For the closed autofretted process, autofretted pressure was affected by the gap amount between the mold and the barrel.
Research on obtaining method of rotor moment of inertia of synchronous generator set suitable for different rated speed
Authors: Wen Libin 
Published: September 2020

Abstract
Aiming at the problem that the moment of inertia of the rotor of the generator set is different from that of the generator set under different load rejection, according to the energy conversion characteristics of the generator set during the rotor rotation, the energy conversion balance equation of the rotor rotation process is put forward, which is applied to the load rejection process of the generator set under different load and calculated and analyzed, and the accurate moment of inertia of the rotor of the generator set is obtained, this method improves the accuracy of kinetic energy of generator, which is one of the parameters of generator model in power grid stability analysis.
Verification of the numerical analysis using a collocated grid system directly solving the quasi-inviscid incompressible flow around a symmetric airfoil
Authors: Suzuki Hiroki , Watanabe Masaya , Hasegawa Yutaka , Mochizuki Shinsuke 
Published: September 2020

Abstract
The present study describes the results of validating a high-quality computational scheme of kinetic energy conservation characteristics under a collocated grid system. In the present study, the pseudo-inviscid incompressible flow around the Kármán-Trefftz airfoil is analyzed. In this analysis, the kinetic energy conservation error is reduced by temporally evolving the governing equation using pressure increments in fractional steps. This sufficient conservation of kinetic energy is validated using an inviscid homogeneous isotropic fluctuation field. The velocity field obtained by this analysis is compared to that of the potential flow obtained using the Kármán-Trefftz airfoil. The numerical analysis is also validated using the lift coefficient profile as a function of a small angle of attack.
Model of thermal power plant considering water spray desuperheater for power system analysis
Authors: Wen Libin 
Published: September 2020

Abstract
It is of great significance to build a model of the water spray temperature reduction system that is more suitable for electrical simulation, and apply it to the existing thermal power plant model for the simulation analysis of today’s complex thermal power plants. Based on reasonable thermodynamic assumptions, the law of conservation of energy and the law of conservation of mass, a transfer function model of a water-jet cooling system suitable for the simulation of a thermal power plant is established by using mechanism modeling. The relationship between these variables and the effect of each variable on the output variables verified the correctness of the model. A steam turbine system considering the influence of the boiler was further established, and a simulation analysis of the operating characteristics was performed, which verified that the influence of the boiler on the dynamic response of the unit is necessary in the long-term stability analysis. Finally, combined with the model established in this paper, a dynamic model of thermal power unit with water spray temperature reduction device was established. The model is simulated with the step disturbance of velocity, the disturbance of cooling water flow and the disturbance of opening door. Based on the simulation results, the action response characteristics in the process are analyzed. It is verified that the model can accurately describe the main steam parameters and power regulation when applied to large-scale power grid transient simulation.
Grab application of remote operation service robot
Authors: Wang Xia , Zhao Tong , Wang Ding 
Published: September 2020

Abstract
The remote operation service robot can realize remote wireless control through the handle to help people with inconvenient movement to grasp objects. In this paper, based on the robot, the kinematic analysis is carried out to obtain the coordinate transformation of the mechanical fingers relative to the ground, and the dynamic analysis is carried out to obtain the driving torque required by each motor. The inverse kinematics of the manipulator is solved by MATLAB to obtain the joint parameters of the manipulator. Raspberry PI is used as the main control board, the handle sends out instructions, Raspberry PI judge instructions, and communicates with C8051F040 development board located in the manipulator through CAN bus. The mechanical finger realizes open-loop control through micro stepping motor, and finally realizes the remote operation of the service robot to grab objects.
Development and design of Bluetooth intelligent car
Authors: Wang Yongjie 
Published: September 2020

Abstract
Bluetooth is a kind of radio technology that supports short distance communication (usually within 10m). It can exchange wireless information among many devices, including mobile phones, PDAs, wireless headphones, laptops, and related peripherals. Using “Bluetooth” technology can effectively simplify the communication between mobile communication terminal devices, and also can successfully simplify the communication between devices and the Internet, so that the data transmission becomes more rapid and efficient, and broaden the way for wireless communication. This paper starts from the mechanical design and electrical control design of the intelligent car, designs the software and hardware of the Bluetooth intelligent car, mainly involving several technologies: wireless transmission technology; AVR single-chip technology; pulse width speed regulation and other related technologies. Realize the function of controlling the car forward, backward, left, right, acceleration and deceleration with Bluetooth.
Application of highly deviated well injection technology in Huabei Oilfield
Authors: Wang Yao , Han Mingzhe , Chen Junzheng , Li Ran , Zhang Xu , Liu Zhijuan , Wang Shuangyan , Wei Yuhao , Cheng Xiangfa , Xiong Wei , Liu Dayong , Huang Bohua , Li Xueying 
Published: September 2020

Abstract
With the deepening of oilfield development, the amount of highly deviated (≥30°) layered water injection wells have increased year by year. In order to solve the technical bottlenecks such as poor sealing of the columns and short effective period of dispensing. The self-supporting step-by-step releasable packers with the outer diameter of 114mm and the highly deviated well ball seat are developed. The packer integrates the function of centering-righting, ball centering, spiral righting and stepping unblocking and the ball seat has self-locking function and able to meet the requirements of pipe string used in highly deviated wells within 60°. Through the field application, a highly deviated well-dispensing process technology suitable for the characteristics of Huabei Oilfield has been formed, it has a strong popularization and application value.
Design and analysis of energy supplement system of waterfowl-type unmanned vessel platform
Authors: Fang Zifan , Hong Junpeng , Qin Lin , Liu Jin , Xie Zhiheng , Xie Zheyu 
Published: September 2020

Abstract
For the marine unmanned vessel platform’s long-distance navigation, a waterfowl-type unmanned vessel platform energy supplement system consisting of a wave energy collecting mechanism and a hydraulic conversion system was presented. A four-link acquisition mechanism and an energy conversion system are designed. The wave force on the float and the vertical wave force on the unmanned vessel platform were calculated by Matlab software. Based on the energy flow conversion process, the Adams and AMESim co-simulation model of the system was established. The energy conversion efficiency of the system under different sea conditions was calculated. The research shows that it can realize the continuous energy supplement and provides a reference solution for solving the problem of continuous energy supply in marine unmanned vessel platforms.
Numerical modeling of Vickers indentation on polycrystalline alumina
Authors: Liu Zhonglei , Wang Chao , Chen Zhanying , Rong Yiming , Li Xuekun 
Published: September 2020

AbstractIndentation techniques are usually simple and effective methods to characterize ceramics properties. This article establishes a numerical model of Vickers indentation by using the general exponent Drucker-Prager model, which is suitable for materials whose compressive yield strength is much higher than tensile strength. In addition, a standard method for calculating the diagonal length of indentation is also proposed. Using this FE model, several numerical simulations of Vickers indentation process are conducted. Then, through measuring the indentation morphology with the proposed method, the Vickers hardness is calculated, which has excellent agreement with the experiment results. The comparison results of simulation and experiment show that the proposed numerical model is robust and effective. It is very promising in modeling the indentation process.
Error analysis and kinematic calibration of a new 3-PRS parallel mechanism
Authors: Sun Fuwei , Chen Guoqiang , Chen Shuisheng , Li Yongsheng , Yuan Jingshuai , Zhang Qin 
Published: September 2020

Abstract
Taking a new 3-PRS parallel mechanism as the research object, error analysis and kinematics calibration are carried out. Combining with inverse kinematics, the parameter error of the mechanism is analyzed comprehensively. a calibration method of inverse kinematics based on structural parameters and genetic algorithm is proposed, and the error calibration model of 3-PRS parallel mechanism is deduced. The calculation by MATLAB shows that the reverse motion error calculated by nominal machine tool structural parameters is larger than that obtained by calibrated structural parameters. The position of the three cylindrical and spherical hinges after calibration is closer to the nominal position. It shows that the error calibration can correct the machine tool structure and guide the subsequent installation and debugging of the machine tool.
Modelling and analysis of fuel temperature during fuel injection process of electronically controlled injector
Authors: Wang Jun , Liu Yanbin , Jin Yi , Zhang Youtong 
Published: September 2020

Abstract
In order to explore fuel temperature variation during the process of fuel injection, mathematical model of the fuel heat-temperature in electronic controlled injector (ECI) is founded, fine thermal simulation modelling of ECI is fulfilled by software AMEsim, fuel temperature change of different place in ECI is analysed. The analysis results show that injection pressure and initial fuel temperature have a great effect on the fuel temperature of the needle chamber and the control room, injection duration has little influence on the fuel temperature of the needle chamber, the fuel density decreases with the increase of fuel temperature under a certain pressure.
Study on strength reliability of actuator piston parts
Authors: Li Wending , Shi Guanglin , Dong Wenyong , Qiu Haihui 
Published: September 2020

Abstract
On the basis of the stress–strength interference model and reliability perturbation theory, this study applies the second-order distance method to analyze the reliability of actuator parts under the normal distribution of random parameters with ring as the dangerous section. The method of equivalent normalization of non-normal distribution parameters is also implemented in the reliability analysis of the tensile strength of ring sections. The design method described in this paper is applied to the design process of the piston rod of a carrier rocket servo mechanism. The influence curve of random parameters on reliability is drawn. A calculation software is established. This study provides theoretical support and practical method for the design of axial bearing parts with circular section.
Design and analysis of a lower extremity exoskeleton with the humanoid knee joint
Authors: Li Tingting , Li Jian , Han Zhonghua , Yang Jiechao , Li Qiang 
Published: September 2020

Abstract
Exoskeletons should have certain capabilities and characteristics such as human performance enhancement, low impedance and comfortable. In this paper we present a lower extremity exoskeleton. In order to achieve the characteristics of exoskeletons mentioned above we choose the Series Elastic Actuator (SEA) as its driver. A novel humanoid knee joint is introduced into the exoskeleton to improve the coordination between exoskeleton and human body during work progress. A stable control method is proposed to achieve the exoskeleton joint following motion. Finally, the feasibility of control algorithm is verified by simulation.
Analysis on screw preload condition of acoustic beacon in high water pressure environment
Authors: Chen Yang , Dong Shichao , He Junbo , Xiao Haitao , Sun Jialu 
Published: September 2020

Abstract
The acoustic beacon is mainly assembled by using screw thread couplings between caps and shell. The products are always affected by heavy loads when operating under high water pressure. In this paper, to investigate the influence of screw thread couplings on acoustic beacon strength under deep water condition, the structural stresses and the distributions of the acoustic beacon with different pre-tightening torque of screw thread under particular water pressure is analysed by using finite element method. The variations of stresses which is relative to the pre-tightening torque of screw thread are also analysed and proposed as the form of line chart. The results indicate that the acoustic beacon strength can be improved by increasing the pre-tightening torque of screw thread, and the line chart can be used to determine the most suitable pre-tightening torque while assembling the products.
Modal analysis of monorail rocket sled and its cabin connections
Authors: Hu Bing , Xia Hongli , Hao Fenfen , Li Hui 
Published: September 2020

Abstract
Structural stiffness is an important dynamic parameter for the rocket sled. In this paper, both modal test and finite element modal analysis are carried out on the certain monorail sled and its two different cabin connection kinds which are bolt and thread. By comparing the natural frequencies and modal shapes obtained by test and simulation methods respectively, it is found that the stiffness of bolted cabins is consistent with the simulation results, while the threaded cabins performs a severe stiffness degradation due to the thread clearance, which also causes the natural frequencies of the completed sled to be reduced and the modal shapes to be inconsistent with the simulation results. The finite element model of threaded connections is modified by giving anisotropic material properties to the connected elements, and the simulation deviation is reduced. According to the analysis results of two different kinds of cabin connections, threaded cabins on the final assembled rocket sled are strengthened by welding. The modal test results of the reinforced threaded cabin connection indicate that negative influence of the threaded connections is eliminated and the natural frequency and vibration mode are very close to the simulation results.
Influence of wheel-diameter difference of the same locomotive on ride quality of locomotive
Authors: Zhao Bin , Liu Fei , Li Ruiyu , Wang Jianming , Liang Lin , Luo Ailing 
Published: September 2020

Abstract
The existence of wheel-diameter difference of track locomotive will directly affect the motion performance of locomotive. In this paper, the creep force of coaxial wheel-diameter difference is analysed, and the dynamic model of 2-axle bogie locomotive is established by SIMPACK software. Based on the study of two typical wheel-diameter difference of the same bogie, 10 special working conditions of wheel-diameter differences of the same locomotive are put forward. The effects of different working conditions and different wheel-diameter differences of the same working condition on the straight line motion performance of locomotive are analysed. The results show that, the lateral displacement and lateral ride quality index of locomotive body increase with the increase of wheel-diameter difference under the same working condition, and they do not exceed the safety limit. The change of wheel-diameter difference has little effect on the vertical ride quality index of locomotive body. According to the lateral displacement of the locomotive body, the 10 working conditions are divided into three grades. The third grade (working condition 4, working condition 5, working condition 8 and working condition 11) is more conducive to the safe and stable motion of the locomotive. Therefore, in the wheel matching installation and repairing process, priority should be given to the arrangement of wheel-diameter difference of the same locomotive in the third grade. This will provide a reference and basis for the scheme of locomotive wheel economic repairing.
Simulation analysis of the fertilizer ejecting device of corn fertilizer applicator based on EDEM
Authors: He Yakai , Li Cuiling , Zhao Xueguan , Gao Yuanyuan , Li Si , Wang Xiu 
Published: September 2020

Abstract
In order to improve the fertilization efficiency of corn fertilizer applicator in the Huang-Huai-Hai area, according to the requirements of the wide-row crop fertilizer requirements, a centralized type fertilizer ejecting device was designed. Straight outer groove-wheel was regarded as research objects in this paper. The simulation model of fertilizer ejecting device was established and the simulation analysis of fertilizer ejecting was carried out by using the discrete element simulation software (EDEM). In the simulation environment, the requirement of fertilizer ejecting amount was 300kg·hm-2, the forward speed of fertilizer ejecting device was set to 5.4km·h-1, and the working height of fertilizer axis was 250mm. The effect of different working lengths of fertilizer ejecting wheels on the fertilizer performance was analyzed. The simulation results showed that when the working length of fertilizer ejecting wheel was 28mm, the uniformity variation coefficient of fertilizer ejecting was 14.62%, and the accuracy rate of fertilizer ejecting was 95.95%, which indicated that performance of fertilizer ejecting was better. This research results can provide references for the subsequent development of corn fertilizer applicator.