bluuebunny/crossref_metadata_2025 huggingface dataset:
Progress of automatic vertical drilling systems: selection for deep wells with high temperature and pressure in China
Authors: Sun Weiguang , Song Weiqiang , Ni Hongjian , Lou Erbiao , Sun Xue , Zhang Shichuan
Published: July 2021

Based on the working principles of various automatic vertical drilling systems (VDS), they are divided into rotary-pushing type and slide-pushing type. Then, the technical advantages and applicable scope of the two types VDS are analysed. Thirdly, the reliability of different VDS is presented based on the latest application statistical data. Fourthly, suitable VDS are selected for a certain deep well with high temperature and pressure. Finally, the development trend of the VDS is predicted based on the analysis of typical application cases. The results show that, the existing VDS could almost meet the technical needs of rapid drilling in the middle-deep sections with high formation dip angle, although the reliability of electronic components and wear resistance of the push pad still need further improvement. New type VDS, that is miniaturized (suitable for small boreholes) and resistant to high temperature and high pressure, is in urgent need to fill the gaps in the market segment recently. Domestic independent VDS have made great progress in achieving the technical goal of anti-inclination, some even surpasses imported products in key indicators such as temperature resistance. The research results can provide support for the drilling company to optimize the VDS based on engineering-geological conditions.
Research on Thermal Simulation Improving the Components’ Soldering Quality in Electronic Module
Authors: Yang Hai , Jing Zhu
Published: July 2021

This paper describes a method that could exactly optimize and improve the soldering quality of the electronic module. Firstly, a sample of temperature measurement was proposed. Through the temperature rising, heat preservation, temperature rising, soldering and cooling, the sensors could able to accurately and sensibly record and present each temperature data which set on the sample. At the same time the soldering cure was also measured. Secondly, through the analysis and research of vapor-phase soldering technology based on condensation theory, referring to the relevant modeling and simulation analysis methods, a thermal simulation model was established (size: 13.7mm × 45mm × 16.5mm). The ANSYS was used in this thermal simulation and the measured temperature curve, material parameters and other boundary conditions were loaded. The transient thermal simulation method was adopted and the temperature variation on sample during vapor-phase soldering was simulated. A maximum error of 2.67°C between simulation and measurement results, error rate is only 1.2%. Therefore, this simulation method can effectively perform the change of temperature with time in the real vapor-phase soldering process. After that, the optimized vapor-phase soldering temperature curve and soldering process parameters were used to carry out the vacuum vapor-phase soldering test in the assembly. The dimensions, materials and other parameters of the components used in the test were completely consistent with the simulation model. Two Sn63Pb37 solder rings were used in the test and the vacuum was also carried out. Through the X-ray inspection results, the optimized vapor phase soldering temperature curve has no soldering voids and well soldering consistency, which meets the requirements of high-quality soldering and improves the assembly quality of electronic products.
Study on Main curvature of Stress Relaxation Modulus of a Double-base solid propellant
Authors: Jian-bin Zhang , Lei Guo , Guang-hua Li , Bing-ju Lu , Dong Cheng
Published: July 2021

The mechanical properties of a double-base solid propellant under quasi-static and dynamic conditions are studied experimentally. According to the time-temperature equivalence of a double-base solid propellant, the main curve of stress relaxation modulus and temperature-dependent material parameters are obtained by using the stress relaxation test results at different temperatures. Based on the analysis of the temperature spectrum of a double-base solid propellant material, the main curve of stress relaxation modulus and temperature-dependent material parameters of the double-base solid propellant material are obtained by using the equivalent principle. The results show that the dynamic test results are better. The database of the dynamic stress relaxation modulus main curve should be used as the basic parameters of the constitutive model analysis and the structural integrity analysis of the double-base solid propellant, which lay the foundation for the type selection and the structural integrity analysis of double-base solid propellant grain.
Experimental Research on the Water Spray Hole Flow Coefficient
Authors: Jian-bin Zhang , Dong Cheng , Ben-shuai Fu , Guang-hua Li , Bing-ju Lu
Published: July 2021

The water spray hole flow coefficient is one of the important parameters that have great effect on the calculation accuracy of the spray water quality second flow. The test system is designed on the water spray hole flow coefficient in this study. The test results are obtained on the water spray hole flow coefficient under different working conditions. The results showed that the water spray hole flow coefficient is not constant but a function for time. The water spray hole flow coefficient increase with the increase of the number of blowhole. Although the rest results have a certain error, but this study fills the blank no test results on water spray hole flow coefficient. That also provides the technical support on improving launch internal ballistic calculation accuracy of the dynamical system and model improvement.
Research on 3D printing platform of blockchain for digital spare parts management
Authors: Zhang Shucheng , Lin Zhiyu , Pan Haochi
Published: July 2021

In the era of digital manufacturing, 3D printing has great potential in the spare parts supply chain due to its characteristics of real-time response manufacturing. In order to improve the docking efficiency of the supply and demand sides in 3D printing, the development of 3D printing cloud platform has received more and more attention. However, the traditional 3D printing platform can neither meet the needs of rapid production in actual production scenes nor create a safe and efficient data sharing mode. In order to meet these challenges, this paper proposes a 3D printing platform based on blockchain. First of all, the production standard identification and coordination solutions of spare parts suppliers are established to carry on the rapid qualification certification to the supplier. Secondly, the blockchain technology on-chain off-chain storage scheme is developed to achieve efficient sharing of 3D printed digital files under the premise of full property rights protection. Third, the product traceability service is developed to ensure the safety and transparency of spare parts. Finally, the effectiveness of the blockchain 3D printing platform is confirmed through the development of the prototype system.
Simulation Model and Verification of Heat Transfer Characteristics in Aircraft Cabin Bulkhead
Authors: Chengyun Wu , Yi Cao , Xuhan Zhang
Published: July 2021

The calculation of heat transfer in aircraft bulkheads is of vital importance to the design of aircraft cabins. In this paper, a numerical model for the fluid-solid coupled heat transfer of aircraft cabin bulkhead and air in the cabin is developed, including fluid/solid area division, network strategy, turbulence model and numerical discrete method, and the model is verified based on the experimental data. The results show that the proposed model can accurately predict the wall temperature and the air temperature of the aircraft cabin with a deviation of less than 1.02°C in the working range of -15∼25°C, and the prediction deviation for the air velocity is within ±10%. The heat transfer from the cabin to the bulkhead accounts for 7.5% of the total heat transfer. The main component of the thermal resistance of the cabin bulkhead is the thicker solid area, and the inlet air temperature is the key parameter for the design of aircraft cabin. The research results provide an important theoretical basis for the optimal design of the thermal environment of the aircraft cabin.
Application of the Sub-Sea Analysis (SSA) capability in numerical simulation of underwater explosion
Authors: Zhengpeng Tang , Xiangyu Li
Published: July 2021

In order to solve the problem that LS-DYNA fluid-solid coupling algorithm is not suitable for remote underwater explosion simulation and improve calculation efficiency, the numerical simulation of remote underwater explosion is carried out for the subsea analysis function in LS-DYNA. The dynamic response process of ship hull girder under underwater explosive load is analyzed by comparing it with the general software AUTODYN numerical simulation. The method reflects the loading process of underwater explosion load on structure to a certain extent. The calculation speed is fast, but the accuracy is not high and the error of bubble pulsation process is large.
Research on Intelligent Comprehensive Support Technology and Application of Complex Equipment
Authors: Pengpeng Liu , Jine Huang , Yanyan Liu
Published: July 2021

At present, the complex equipment logistics support system often faces the situation of local logistics support capacity surplus or insufficient, which presents the disadvantages of high cost and low efficiency. The concept of equipment autonomous logistics support and perception response support emphasizes the importance of network as the center, aiming at the crucial problems of logistics support management, it puts forward that equipment logistics support management must realize full-dimension, globally controllable, wholly-owned, and end-to-end seamless integration from the equipment platform to the entire support architecture. A three-level network architecture is designed to realize real-time perception of panoramic situation through equipment technology status sensor and resource sensor, and to carry out scheduling and management through decision support system, and to organize coordinated operation of logistics manpower, support resources and support facilities.
Study on the characterization technology of hiding power of powder coating
Authors: Xue Bing , Yan Ran , Wang Can , Zhang Huayuan , Yue Yongyong , Luo Jing
Published: July 2021

In this paper, a method to characterize the hiding power of powder coating by dispersing powder coatings in various dispersants and brushing obtained suspension coating was studied. When colorless, transparent and low-viscosity reagents reagent, containing epoxy functional group, is used as the dispersant of TGIC polyester thermosetting powder coating, the hiding power of this kind of powder coating can be accurately determined. When the dispersion concentration of powder coating is in an appropriate range (mass fraction 32%-45%), the hiding power has nothing to do with the concentration, and the test results reflect the properties of powder coating itself.
Research on microstructure evolution and mechanical properties of steering shaft teeth after pre-heat treatment and carburizing-quenching processes
Authors: Zhang Yishuai , Wang Tao , Fu Jia , Sun Hongxing , Li Jiqiang , Liu Hua
Published: July 2021

The influence of pre-heat treatment and carburizing quenching on microstructure and properties in steering gear is studied. The CCT curve and TTT curve of 20CrMnTiH are calculated by JMatPro software. According to the phase transformation theory of undercooled austenite, the pre-heat treatment process is designed and the carburizing and quenching experiments are carried out in a gas carburizing furnace. Results show that the undercooled austenite begins to transform at 814.1 °C and shows unstable at 650 °C, at which the phase transformation speed is the fastest; By controlling the cooling rate of our designed air cooling system, transformation temperature and transformation time during the undercooled austenite transformation, the metallographic structure of axle teeth after pre-heat treatment can reach grade 1, with the brinell hardness distribution is 159HB-166HB and the hardness difference less than 7HB. After carburizing and quenching the carbide grade in the gear surface can reach to grade 1. The acicular martensite and retained austenite can also reach to grade 3. In the surface of the gear the hardness is 704HV. With the request of the engineering technical standard of 0.7mm-0.9mm, the effective hardened layer depth is about 0.85 mm. This research provides a technical basis for the fatherly research on distortion characteristics.
Structure and Properties of Recycled Polyester-cotton Blended Fiber/HDPE Composite Board
Authors: Huili Zhao , Chifei Wu
Published: July 2021

Recycled polyester-cotton blended fiber/high density polyethylene (HDPE) composite boards were prepared by internal mixing and compression molding two-step process with maleic anhydride grafted ethylene polyethylene-octene elastomer (POE-g-MAH) as compatibilizer. Two kinds of recycled polyester-cotton blended fiber were used as reinforcing fibers, including polyester-cotton long fiber (F1) and polyester-cotton short fiber (F2). Microstructure and properties of the composite boards reinforced with F1 and F2 were characterized by SEM and electronic universal tensile testing machine. The results showed that the comprehensive mechanical properties of polyester-cotton blended long fiber composite boards (F1HC4) and polyester-cotton blended short fiber composite boards (F2HC4) were optimal with a compatibilizer content of 4%. F1 had a significant effect on the mechanical properties of the composite boards in two kinds of fiber with the same addition of compatibilizer. The tensile strength, flexural strength, impact strength and of F1HC4 were 56.4%, 36.4% and 87.5% higher than that of F2HC4, respectively.
Thermal behavior test and characterization of a capsicum oleoresin (OC) composite material used for burning tear bomb
Authors: Haolong Zhai , Xiaoping Cui
Published: July 2021

In order to study the thermal behavior of a capsicum oleoresin (OC) composite material used for burning tear bomb, the single component and the composite (KClO3+ lactose + OC) were tested by HS-STA-002 synchronous thermal analyzer. Differential scanning calorimetry (DSC) and thermogravimetric analysis (TG) were performed at a heating rate of 10°C/min, the results show that the composites have good compatibility because the characteristic peaks of each component in the composites have little change compared with the relative characterization of the composites. The temperature range of the best volatilization effect of pure OC is between 250°C∼350°C; when the temperature is lower than 250°C, it is unfavorable to the thermal diffusion of OC; when the temperature is higher than 350°C, OC will undergo thermal decomposition. In the composite system, the temperature range of the best volatilization effect of OC is between 230°C∼330°C. Compared with the temperature range of the best volatilization effect of pure OC, the temperature range of OC is shifted to the left, but the range is smaller. All these findings can provide theoretical guidance for the formulation design and optimization of this kind of composites.
A Novel Handheld Device: Application to in Situ Bioprinting Compound Dressing for the Treatment of Wound
Authors: Tianyuan Yin , Yi Zhang , Zhian Jian , Yuanyuan Liu
Published: July 2021

In recent years, Bioprinting technologies have been advancing at the convergence of automation, digitalization, and new tissue engineering (TE) approaches, In-situ bioprinting may be favored during certain situations for skin wound healing. The main advantage of in-situ printing is that the printed wound surface has good adhesion, namely the print of dressing can full fill the defect out of the wound, can adapt to different positions (joints) of the different types of wounds. In addition, the free deposition of materials and the properties of materials are well combined with the wound surface in the printing process, sticking to the wound surface and reducing the pain caused to the injured by the process. Handheld device to achieve in-situ printing, simplifies the surgical process, portable, easy to operate, can be used in emergency scenarios. Moreover, wound healing is a dynamic and complex process that contains several sequential phases. Rapid hemostasis and continuous bacteriostasis have always been problems in wound healing. Here, we firstly propose a hand-held device that combines multiple processes (spray, extrusion, electrospinning) and is oriented to accurate wound management. Secondly, we used this device to achieved the stable film formation of a variety of materials, and has the key functions of hemostasis, bacteriostasis and promoting healing. Finally, we highlight the potential of this device for wound healing applications.
A Predictive Method of Thermal Expansion Coefficient of POSS Reinforced Silicone Materials
Authors: Wei Huazhen , Wang Danyong , Li Shuhu
Published: July 2021

Silicone resin can not only withstand high temperature, but also form S1O2 layer with better heat resistance after ablation at high temperature, which rarely reflects electromagnetic wave. In the manufacturing process of POSS/silicone resin, if the content ratio of POSS can be effectively controlled, the comprehensive properties of the materials can be significantly improved, many weaknesses of the composites can be improved, and the real problems such as the stiffness and strength of the wave transparent composite still need to be greatly improved can be solved. A prediction method for thermal expansion coefficient of POSS reinforced silicone materials is developed, which is convenient for engineering application. The relationship between microstructure and thermal expansion property of materials is understood systematically and accurately, so that the prediction of thermal expansion property and material design are possible.
Influence of Temperature and Concentration on Viscosity of Complex Fluids
Authors: Wenhao Zhang
Published: July 2021

With the spread of lubricating oils, the usage of viscosity becomes more and more significant in various industries. This essay is used to determine the relationship between viscosity and the change of concentration and temperature to avoid problems during production process. This research uses the high-degree function and exponential function to simulate the change trend of viscosity due to the two variables. Through research, the author discovered the exponential relationship between the temperature as well as concentration and viscosity of lubricating oils and other complex fluids. Based on the results of this research, the enterprise can also avoid excessive wear of the machine and high waste in the production process.
The effect of annealing temperature on Ga2O3 film properties
Authors: Zhang Xi , Jiang Dayong , Zhao Man , Zhang Haixin , Li Mingyang , Xing Meijiao , Han Jichao , Romanov Alexey E.
Published: July 2021

Using Radio Frequency Magnetron Sputtering (RFMS) equipment, gallium oxide (Ga2O3) films were deposited on sapphire substrates. Then the samples were annealed at 700 °C, 900 °C, and 1100 °C for 120 min in the air atmosphere to convert them into β-Ga2O3 films with different crystalline quality. The effects of annealing temperature on the properties of β-Ga2O3 thin films were investigated. The crystal structure and surface morphology were tested by X-ray Diffraction (XRD), absorption spectroscopy, and Atomic Force Microscopy (AFM). The results obtained show that, within a certain range, as the annealing temperature increases, the intensity of the XRD peaks increases, the Full Width at Half Maximum (FWHW) – decreases. The crystal grains “engorge” as the temperature rises, and the degree of crystallinity of the samples becomes better.
Effect of Zn on corrosion behaviour of biodegradable Mg-Zn-Mn alloys evaluated by FE prediction and in-vitro testing
Authors: Lu X.Z. , Chan L.C. , Zou X.J. , Lai C.P.
Published: July 2021

Mg-Zn-Mn (ZM) alloy shows great potential in biomedical applications due to its biocompatibility and bio-essential element composition, as well as its favourable mechanical and degradation properties. This paper aims to explore the effect of Zn on corrosion behaviour of ZM alloys via finite element (FE) prediction and in-vitro testing. Microstructure analysis showed that Zn had the grain refinement effect, and the second phase of Mg-Zn between grains increased with the increase of Zn content, which improved the mechanical properties of the alloy significantly at the cost of acceptable reduction in plasticity. After a continuum damage mechanics (CDM)-based degradation model was applied to the FE package, the corrosion process of the ZM alloys was predicted. The results indicated that the grain boundary had poor corrosion resistance while the second phase facilitated delaying corrosion expansion. Furthermore, in-vitro tests were carried out and consistent results were obtained, i.e., the grain refinement made the entire corrosion process more uniform and severe corrosion in local areas was avoided, and the intergranular second phase was beneficial to delay the corrosion process. This study suggested that Mg-Zn-Mn alloy has satisfactory mechanical strength and controllable corrosion rate, which should be a promising candidate for future biomedical applications.
Three Kinds of Novel Bioabsorbable Interface Screws: Evaluation of Mechanical Properties
Authors: Meng Xianyuan , Chen Lihua , Dong Wenxing , Shan Lutong
Published: July 2021

With the development of medical technology and materials science, the structure optimization method of bioabsorbable materials for implantable medical devices becomes more and more important, and the absorbable interface screw is the most representative device in implantable medical devices. Based on the previous parametric design method for the loading and structural characteristics of the interface screw, this paper assembled the interface screw and cancellous bone with the tunnel hole and simulated the graft fixation after cruciate ligaments surgery. In this study, through the finite element method, the mechanical properties of interface screws with different structural parameters obtained by parametric design were comprehensively evaluated from the aspects of stress and strain energy density.
Study on static recrystallization behavior of martensitic stainless steel
Authors: Qi Peng , Ren Facai , Xu Jinsha
Published: July 2021

Static recrystallization or sub dynamic recrystallization may occur during multi pass forging clearance of turbine blade. The static recrystallization behavior of martensitic stainless steel was studied by two pass hot compression test. By linear fitting the flow stress data, the parameters in the standard JMAK equation were obtained. Based on JMAK equation, the static recrystallization kinetics model of martensitic stainless steel was established. It provides a basis for the actual forging process of steam turbine blades.
characteristics of the gap-type up-rating conductor used in overhead power transmission lines
Authors: Yang Changlong , Zheng Yang , Yang Feng , Fu Zhongyuan , Xu Chao , Zhang Yang , Duo Junlong
Published: July 2021

This article briefly introduces the current increasing demand for electricity in China, and ordinary aluminum conductor steel reinforced will no longer meet the mand for electricity. For this reason, a new type wire, the gap-type up-rating conductor, is introduced. Under the condition of no wind and no sunshine indoors, the sag and tension of the wire under different spans is measured with sensors and analyzed. Clear and visible results based on experimental data are obtained.
Influences of Laser Remelting on Hot Corrosion Resistance of Plasma-sprayed Nanostructured Al2O3-13wt.%TiO2 Coating
Authors: Wang Dongsheng , Xiao Rui , Qu Guang , Zhou Xinhua
Published: July 2021

Nanostructured Al2O3-13wt.%TiO2 ceramic coatings were prepared on the TiAl alloy surface by using the plasma spraying and plasma spraying-laser remelting composite technology, respectively. Hot corrosion behaviors of these two coatings in 75%Na2SO4+25%NaCl (mass fraction) fused salts under 850 °C were discussed. Moreover, phases and microstructures of specimens after the corrosion were analyzed by X-ray diffractometer (XRD) and scanning electro microscope (SEM). Effects of laser remelting on hot corrosion resistance of coatings were explored. Results demonstrated that hot corrosion of ceramic coating prepared by plasma spraying is serious, but the hot corrosion resistance can be improved effectively after laser remelting. Laser remelting specimens show the higher hot corrosion resistance for two reasons. On the one hand, laser remelting forms a uniform and dense remelting layer by eliminating the lamellar structures and most pores of the coating layer, thus decreasing the corrosion diffusion channels during hot corrosion. On the other hand, laser remelting changes the metastable-phase γ-Al2O3 into stable-phaseα-Al2O3.
Research on Dilution of Laser Cladding Assisted by Pulsed Current Based on Orthogonal Experiment
Authors: Wang Dongsheng , Zhu Yuanyang , Qu Guang , Zhou Xinhua
Published: July 2021

With characteristics of high cladding efficiency, small grain size and low porosity, follow-up feeding pulse current assisted laser cladding can realize online self-healing of cracks on the cladding layer and get a crack-free cladding layer. It is a very promising new laser cladding technology. In this study, effects of cladding parameters (laser power, scanning speed, powder feed rate, pulse current, pulse frequency and pulse width) on dilution rate of coating were discussed through a six-factor three-level orthogonal experimental design method. Results demonstrated that laser power, scanning speed and powder feed rate can influence dilution ratio greatly, while pulse current, pulse frequency and pulse width influence the dilution ratio slightly. Among the top three major factors, laser power can influence the dilution ratio mostly, followed by powder feed rate and scanning speed. The dilution ratio increases with the increase of laser power, scanning speed and pulse width, but it decreases with the increase of powder feed rate and pulse frequency. With the increase of pulse current, the dilution ratio decreases firstly and then increases.
Optimization Steel ingot Mould’ Riser Height Based on Solidification Simulation
Authors: Yadong Xu , Hongyi Guo , Huichao Ge , Yanan Wang , Yun Zhou
Published: July 2021

Solidification process of 13.5t P91 steel ingot with different riser heights were simulated by software and predicted the distribution of shrinkage cavity. The simulation results showed the shrinkage cavity in the precedent ingots is much deeper. The simulation results is agreement well with experiment results. Therefore, the riser height was designed by solidifation simulation and verified by experiments and the results showed that optimized riser height can eliminate shrikage cavity and improve the quality of steel ingot.
Study on Automobile Front-End Structure Based on Pedestrian Leg Protection
Authors: Liu Meng , Sun Fuzhen , Wang Baoming , Wang Jianfeng , Yang Na
Published: July 2021

According to the pedestrian leg protection regulations, a collision with the simplified finite element model of the leg was carried out on the basis of incorporating EPP foam materials with different foaming rates and cushioning into the simplified front-end structure of the car. The results show that the front-end foam energy-absorbing structure of the vehicle cannot meet the pedestrian leg protection regulations. This paper designs a thin-walled steel structure and applies it to the front-end structure of the vehicle. After collision simulation with a simplified finite element model of the leg, the pedestrian’s tibial acceleration, knee joint shear displacement and knee joint bending angle are compared and analyzed. Pedestrian leg injury parameters, the results show that thin-walled steel structure is more suitable for giving full play to the energy absorption effect in an environment with insufficient energy absorption space than foam energy absorption structure.
Theoretical comparison of rheological properties of high-viscosity municipal sludge and magnetic liquid
Authors: Xing Feifei , Ruican Hao , Tian Xiaoqiang , Ji Jun
Published: July 2021

The composition and structure of sludge determine its complex rheological properties. When the shear stress is small, the deformation of the structural skeleton appears elastic. As the shear stress increases, the structural skeleton begins to break until it is completely destroyed. In this process, it shows viscoelasticity, and its viscosity gradually dominates. A part of the basic fluid flows out from the damaged structural skeleton, causing the sludge to change from deformation to flow, the shear stress at which it starts to flow is called the yield stress. After the flow, the viscosity decreases with the increase of the shear rate, which is called the shear thinning characteristic. Magnetic fluid is a new type of magnetically sensitive smart material. In the past fifty years, a large number of results have been achieved in the research on the rheological properties of magnetic fluids. However, due to the extremely complex anisotropic structure formed inside the magnetic fluid under a magnetic field. At the same time, the macro-rheological experiment lacks systemicity, and it is urgent to integrate the research results obtained by different experimental methods. Even in the field of the most fully studied magnetic viscosity effect, based on strong idealization assumptions the chain-micro-model is widely used, it cannot be used to analyze the results of macroscopic rheological experiments.
Research of The Influence Mechanism of Multi Gradient Printing on Sand Mold Performance
Authors: Zheng LI , Zhongde Shan , Feng Liu , Yuelong Ran
Published: July 2021

In this paper, multi gradient sand mold sample printing was carried out based on the gray printing technology of sand mold 3D printing, and the influence of gradient distribution of resin addition in sand mold on the property of sand mold was studied. The results showed that the increase of resin addition gradient in sand mold would result in the decrease of tensile strength of sand mold with the constant total resin addition. The bending strength and air permeability of sand mold were mainly affected by the surface resin addition and gradient distribution. With increase of surface resin addition, The bending strength of sand mold decreased, and of which the air permeability increased at the same time. And the increase of gradient spacing between adjacent resin addition gradients in sand mold would lead to the increase of sand mold air permeability and the decrease of tensile strength and bending strength. The result also showed that The surface hardness of the sand mold increased with the increase of the resin content of the surface layer, and had nothing to do with the gradient distribution of the resin content.
Wrinkle analysis and optimization of large-scale membrane
Authors: Zhenyu Zhao , Yujia Zeng , Xianpeng Zhang
Published: July 2021

Wrinkles greatly affect the viewing quality of projection screens. Based on the bifurcation buckling theory, a modified model of screen was established. Various methods were introduced to improve the convergence and accuracy of the model. The causes of wrinkles were analyzed. It is found that the crescent wrinkles on side edges were caused by the free boundary conditions while the divergent wrinkles were resulted from the non-uniform displacement of the bottom edge. The simulation and measured results fit well on wave number, amplitude, wavelength, etc. The screen was optimized according to the analysis results and a perfect wrinkle-free screen was achieved after optimization. The method in this paper is proved applicable, accurate and convenient, which can greatly save time and cost for engineering design of large-scale wrinkle-free membrane.
Influence of Material Properties on Tire/Road Noise for Non-destructive Pavement Condition Assessment
Authors: Liu Hao , Zhang Yiying , Xu Zhengwei , Hou Xiaoning
Published: July 2021

With the purpose of using tire/road noise for pavement condition assessment as a non-destructive test method, an investigation on the influence of pavement material characteristics on tire/road noise is conducted. The acoustic data is collected by a directional microphone mounted behind the rear tire on the passenger’s side of a test vehicle, driving over different sections of pavements with different material properties. The tire/road noise under 2000 Hz is extracted to investigate how it is influenced by the pavement features, such as macrotexture, porosity, top-layer thickness, and top-layer stiffness. The macrotexture, which mainly reflects pavement friction, exhibits high relevance to the tire/road noise below 1000 Hz. The top-layer stiffness of pavement could be distinguished from the sound pressure level at peak frequency between 700 ∼ 1300 Hz, the larger stiffness coming with higher amplitude of sound pressure level (SPL) at peak frequency. The results show high potential to assess pavement friction by the tire/road noise starting from macrotexture measurement. Moreover, the consistency of paving quality or sudden change of pavement subsurface structure can be recognized by looking into the spectrum features at peak frequency area of tire/road noise.
Study on penetration performance of Zr-Ti-W alloys under high speed impacting process
Authors: Xing Lina , Liu Xingwei , He Chuan , Li Chenhui , Li Shukui , Liu Jinxu
Published: July 2021

The damage effect of reactive structural materials (RSMs) is one of the focuses in this field. In this study, four new Zr-Ti-W alloys were prepared by adding Ti element on the basis of W-Zr alloys. These alloys have different densities and mechanical properties. The damage effect of these alloys on 18 mm thick Q235 steel plate under the condition of 1600— 1700 m/s impacting speed was investigated. The results show that the penetration power of Zr-Ti-W alloy is mainly affected by the density of the alloy. The higher the density is, the greater the penetration depth and crater diameter of the alloy bullet are. In addition to the high penetration depth and large crater diameter, the 20Ti alloy also exhibits excellent energy-releasing behavior. This alloy has the tremendous potential to be used as reactive fragments in military application. Besides, the Zr-Ti-W alloys designed in this study maintain good integrity under extreme loading conditions, which had successfully overcome the problem of poor overload resistance of W-Zr alloys.
Typomorphic peculiarities of typical metal mineral and its effect on washability
Authors: Wang Jianguo
Published: July 2021

The scale characteristics of metal minerals generally include mineral form, structure, chemical composition, deposit state, crystal development, thermoelectric coefficient, density, common companion minerals, content, crystal cell parameters, particle size, crystal cell parameters, parcel, isotope composition, main trace elements, physical and chemical environment, complex, carrier, and distribution characteristics. Metal mineral scale largely determines the quality of mineral beneficiation, and it is also one of the basis for the division of mining selection process types. The study of metal mineral scale can provide the basis for ore crushing, beneficiation process classification and process parameters. Different types of metal minerals have a great influence on the beneficiation process, index parameters and ore selectivity of nonferrous metallurgy ores, and also receive more and more attention by relevant personnel in the fields of non-ferrous metals resource exploration, metallurgy and the construction of green metal mines. Therefore, the standard characteristics and optional correlation research of typical metal minerals will have a broad application and social benefits in the field of metallurgical materials.
Topology optimization of wheel drive planetary carrier
Authors: Lv Chang , Yang Yu , Zhan Dong an
Published: July 2021

In order to improve the reliability of the wheel drive system and the service life of the transmission system of the large-tonnage mining dump truck, the finite element model of the planetary carrier is established. According to the stress characteristics, the load, and constraint conditions of the main load, the static analysis and modal analysis are carried out. It is found that the maximum deformation and the maximum equivalent stress are small, and the fifth order modal frequency is high, which can further optimize the structure. Based on the SIMP (solid isotopic material with penalization) interpolation model in the variable density method, the mathematical model of multi-objective function for improving stiffness and reducing flexibility is established by using a compromise programming method. The structure topology of the planetary carrier is optimized to find a more reasonable distribution of materials, and the optimized structure is obtained. Based on the optimization results, the new planet carrier was redesigned, and the dynamic and static performance simulation analysis was performed to ensure the rationality of the improved design of the planet carrier structure. The research shows that the simulation results verify the safety and reliability of the structure, the performance of the optimized planetary carrier can meet the requirements, and the mass is reduced by 14.5%. and a new structure is obtained which is better than the original one.
Gear Modification of Hub Drive Reducer Based on Load Spectrum Test
Authors: Lv Chang , Yang Yu , Zhao Wenxiang
Published: July 2021

In order to improve the reliability of hub drive system and the service life of transmission system for large-tonnage dump truck, the load spectrum test and compilation research of a certain type of mining dump truck were carried out, and the synchronous test acquisition of multi-load spectrum signals of mining dump trucks under complex dynamic conditions were completed. By establishing the standard sample of working mode and designing load spectrum architecture, the load spectrum data processing program was developed, and the outputting load spectrum data results were counted. The transmission model was established by Masta software, and the influence of micro-modification on gear performance was analyzed based on the test results. The results show that the contact stress between the planetary gear and the inner ring gear as well as that of the sun gear and the inner ring gear is reduced. The peak-to-peak transmission error of the high and low speed gear pair are reduced by 31.2% and 29.9%, respectively. For the whole working conditions, the contact stress of the low-speed gear decreases obviously. With the increase of torque, the gear pair contact area and the peak value of transmission error also increase.
Identification of panel acoustic contribution based on patch nearfield acoustic holography
Authors: Xiao Yue , Gao Wei , Chu Changbao , Sheng Jing
Published: July 2021

To identify panel acoustic contribution to the interior sound field, a new method using a modified sound field separation technique based on patch nearfield acoustic holography is presented. An improved sound field separation technique with single semi-closed surface covering the panel of interest is proposed to simplify the measurement process. The outward and inward pressures relative to the hologram surface can be separated directly by establishing the relationship between the measured acoustic pressures and calculated values based on the equivalent source method. The acoustic quantities on the vibrating panel surface can be reconstructed from the free radiated field by getting rid of the inward and the scattered field on the surface. The acoustic power on the panel is obtained as a criterion to evaluate the relative contributions to the interior sound field. A numerical simulation of a scaled car cabin model is investigated and the results demonstrate that the proposed method is an available approach for identifying panel acoustic contribution on the vibrating surface of interest to the interior sound field inside a cavity.
High accuracy on-machine inspection based on rotation theory of multi-axis machine tool
Authors: Zhuang Qixin , Wan Neng , Guo Yanheng
Published: July 2021

On-machine inspection is an important technology for the precision fabrication. Plagued by overlapping structure and positioning error from machine tool, it is a challenge to generate an on-machine inspection path. In this paper, a rotation theory is investigated for balancing efficiency and accuracy. Based on the kinematic chain of the machine tool, an accessible space graph is established to demonstrate this theory. The least rotations, the least direction reversions can be recognized from this graph. In term of these principles, an orientation planning method is proposed for the parts with overlapping free-form surface. At last, the advantages of proposed path generation method are verified on an impeller’s on-machine inspection.
Multi-level peer-to-peer collaborative optimization of smart energy system based on big data analysis
Authors: Bin Wang Guo , Fan Zhao Yi , Chao Wang , Chuang Wang Xiao , Jun Ma , Xiao-Dong Li , Li Zhang
Published: July 2021

The emergence of energy internet has changed people’s understanding of energy production, transmission, storage, conversion and consumption. However, how to promote the development of energy Internet, how to integrate it with various existing energy entities, and really play a role, still need more in-depth research and practice. To solve the problem of optimal management and control of energy and power system, a multi-level peer-to-peer collaborative optimization method for smart energy system based on big data analysis is proposed. In the constructed optimization scheduling model, combined with the demand response characteristics of different energy loads, and based on the time-sharing price of energy such as electricity and natural gas, the user IDR response is described in detail from the aspects of load reduction, transferable load and replaceable load, so that it can effectively cooperate with MES equipment in IEGS, thus minimizing the system operation cost. Multi-source energy storage mode is helpful to improve the economic efficiency of smart energy system, reduce the influence of uncertainty on the actual operation of the system, and reduce the power fluctuation burden of power grid.
Study on the Failure of PP+EPDM-TD20 Based on the Criterion of GISSMO
Authors: Zhi Fu , Yihui Guo , Haizhou Hao
Published: July 2021

In this paper, quasi-static and dynamic mechanical experiments or failure experiments were carried out for the PP+EPDM-TD20, which is the main material of a vehicle instrument panel. The elastoplastic model of the material under different strain rates and the GISSMO failure model based on LS-DYNA software had been established. The accuracy of the material elasto-plastic model and the failure model was compared and verified through the convex test and simulation of the head hammer impact on the instrument panel. The results show that the GISSMO failure model considering the strain rate effect and stress state can accurately predict the fracture failure behavior of PP+EPDM-TD20 plastic materials under complex stress states. This research provides reference for the failure prediction of similar plastic parts under impact conditions.
Human motion pattern recognition method and experiment based on dynamic time warping
Authors: Geng Kaijie , Mo Fan , Zhang Hu
Published: July 2021

In order to make the exoskeleton with better wearing effect, it is necessary to improve the exoskeleton motion intention recognition. In this paper, thin-film pressure sensors and inertial sensors are used to acquire human motion information on a wire-driven exoskeleton robot. The lower limb exoskeleton uses DTW (Dynamic Time Wraping) algorithm to recognize four kinds of human motion patterns by comparing the collected data with database features. The result shows that DTW algorithm can effectively recognize human motion patterns.
Adversarial Attacks Technology in Deep Learning Models
Authors: Lai Yucong , Wang Yifeng
Published: July 2021

Deep learning related to computer vision, speech recognition, and language processing has been developing rapidly over recent years. The applications of these models, however, have underlying risks. Recent studies have shown that small perturbation from adversarial examples could result in false interpretation of the neural network examples and false judgment. Therefore, understanding adversarial example technologies is essential for promoting the safety and robustness of neural network models. This paper summarizes current adversarial example technologies in different applications, discusses the current prospects and challenges, and envision potential future developments in related fields.
A Few-shot Learning algorithm based on attention adaptive mechanism
Authors: Fan Yujie , Li Yu , Zhu Aoqi
Published: July 2021

Deep learning has achieved remarkable results in image recognition, semantic segmentation and other fields. However, the primary premise of training deep learning model is the support of a large number of data sets and labeled samples. Therefore, deep learning is still faced with difficulties in medical, military and other areas where high-quality samples are scarce. Based on the image classification task as the application background, this paper improves a measure learning algorithm based on covariance representation. In the original Few-shot Learning algorithm based on measure learning, Firstly, from the perspective of second-order statistics, the covariance matrix between the feature vectors of each sample is constructed to realize the class representation; Then, an attention adaptive module is introduced to adjust the feature vectors of the class representation and query samples to make them closer to the class representation of the corresponding class. Finally, the experiment is carried out on the public data set(Omnight) to verify the effectiveness of the model. The experimental results show that the classification accuracy of the model designed in this paper is 6% higher than that of the Few-shot learning algorithm based on metric learning.
Research on Emotional Music Reconstruction Method Based on DBN-GRU
Authors: Wang Xuemeng , Guo Bin , Ma Xin , Bai Xuemei
Published: July 2021

In the process of music therapy, in order to solve the problems of short music segments with poor emotional adjustment effect and poor emotional perception of patients, this paper proposes an emotional music reconstruction method that combines Deep Belief Networks (DBN) and Gated Recurrent Unit (GRU). According to the emotional music clips fed back by EEG, the high-dimensional features of music were extracted from the DBN network, and the music features were input into the GRU to construct the emotional music reconstruction model. The accuracy of note prediction of reconstructed music is analyzed, and the results show that this method is better than the reconstruction method using GRU alone. An anxiety evaluation experiment of the subjects was designed, and the Self-rating Anxiety Scale (SAS) of the subjects before and after playing reconstructed music was analyzed, thus verifying that the music generated by the emotional music reconstruction method can effectively alleviate anxiety, which is an excellent tool in the field of music therapy.