bluuebunny/crossref_metadata_2025 huggingface dataset:
Garbage Sorting System Based on Composite Layer CNN and Multi-Robots
Authors: Liang Binyan , Wang Yanbo , Wang Yao , Chen Zhihong , Lin Junqin
Published: October 2020

Object detection technology is the key problem in the garbage sorting system. There are many difficulties in identifying the target in the garbage, such as poor visibility and targets being coverage. The existing image processing methods are difficult to detect the target objects in the garbage sorting system. To solve this problem, this paper proposes a garbage sorting system based on convolution neural network and robots. The CNN network combines the features of three different network layers and predicts the location and angle information of the target objects at the same time, which we called composite layer. Coupled with the training solution of classification regression and angle prediction, the performance of object detection is further improved. The entire sorting system is composed of three subsystems: vision system, electrical system and mechanical system. The vision system is responsible for the image processing and send the position and attitude information to the electrical system. The electrical system controls the different robots to do sorting motion. We construct a TestSet which has 23983 objects to be detected. The experiment results show that our system’s Drop rate is 1.7% and False rate is 4.8%, which is good enough to meet the needs.
Analysis and Forecast of Production Safety Accidents of Housing Municipal Engineering in China
Authors: Zheng Kaixia
Published: October 2020

The problem of production safety accidents in housing municipal engineering has always been a big trouble in China, which has clearly rebounded in recent years. This shows that China’s management performance in this regard still needs to be improved, and there is still a lot of work to be done to prevent and reduce the occurrence of accidents.

This article collected data on 11,948 cases of production safety accidents in housing municipal engineering in 31 provinces, municipalities, and autonomous regions in China from 2003 to 2018. It performs data preprocessing and makes preliminary analysis; uses SPSS software to perform factor analysis, variance analysis, and cluster analysis based on the time and space dimensions of the data. Results show the total number of such production safety accidents is still very large, but there are certain regularities in the time and space dimensions. Relevant government departments and enterprises should focus on controlling the time and region where accidents occur frequently. Besides, this paper establishes the ARIMA model to predict the number of security accidents from 2020 to 2022, and the number of security accidents will continue to increase, so we should be vigilant and prevent it in advance.
A New Profile Least-Squares Approach for Partially Linear Nonparametric Models with Measurement Errors
Authors: Yin Yumeng
Published: October 2020

Partially linear nonparametric models, as a generalization of partially linear models and nonparametric models, have good adaptability and robustness. In this paper, based on the selection of this model, and a new method of contour least squares estimation, the focus is on the estimation of partially linear nonparametric models with measurement errors of covariance. Because when the measurement error is ignored, the parametric and non-parametric components are usually biased estimates. On this basis, we propose a modified contour least squares estimation of measurement error, and also obtain the error variance estimation results. Finally, through numerical simulation, the feasibility of the model proposed in this paper when the covariant has additive measurement error is verified.
Research on the Method of Improving the Quality of Electric Energy Measurement Data
Authors: Sui Bing , Chen Xiaodong , Shou Zeng , Wang Hongzhe , Guo Zhitong
Published: October 2020

In the process of collecting data in the power grid harmonic monitoring and analysis system, changes in load, operating modes, and equipment failures will cause data changes. For the strong correlation index, this paper establishes a mathematical model of the monitoring value for the measurement index, while for the weak correlation index, considering that the monitoring data is a type of time series data, a time series model of the monitoring value for the measurement index can be established, and then the abnormal value monitoring is performed by statistical methods. Moreover, experiments prove that the research method used in the paper to detect whether abnormal data exists in the data can effectively improve the efficiency and provide a guarantee for the quality of data monitoring.
Enhanced Diffraction by a Completely Planar Adjacent Grating
Authors: Xiong Xuehui
Published: October 2020

A completely planar adjacent grating (AG) structure, which is composed of two identical planar dielectric gratings connected by thin metallic or dielectric film, is proposed in the paper. We carry out the numerical investigations of AG according to rigorous coupled-wave approach. The calculated results indicate that the completely planar grating structure is another highly efficient structure to enhance diffraction due to the interaction of surface waves excited by gratings at resonant conditions on both interfaces of the thin connection layer. The results also reveal that the modulation of refractive index is the same crucial role to excite or couple out surface wave as the roughness of the surface does.
Research Methods of Hawking Radiation
Authors: Han Jiaqi
Published: October 2020

Hawking radiation is the product of the combination of quantum field theory and general relativity, and is an important link in the study of quantum gravity. In this paper, Hawking radiation has been briefly introduced, and at the same time, several common calculation methods in the research of Hawking radiation are summarized. Readers can have a certain understanding of Hawking radiation research through this paper and can complete a simple introduction to Hawking radiation based on the introduction of calculation methods.
Numerical solution of special 2D Fredholm-Volterra integral equations using barycentric Gegenbauer interpolation collocation method
Authors: Liu Hongyan , Huang Jin
Published: October 2020

In this paper, an efficient collocation method based on two dimensional barycentric Gegenbauer interpolation is used to solve a kind of special two dimensional Fredholm-Volterra integral equations (2D-FVIEs). The explicit barycentric weights for the Gegenbauer-Gauss nodes not only reduce the complicated calculation but also preserve the numerical stability. The combination of the barycentric interpolation and the Legendre-Gauss quadrature formula transforms the 2D-FVIEs into a system of discrete algebraic equations whose solution is a set of the nodal function values. The numerical experiments provide the maximum absolute error and the convergent order to assess the accuracy and the convergence of the method.
A regularization method for solving the redundant problems in multibody dynamic system
Authors: Yang Liusong , Xue Shifeng , Yao Wenli
Published: October 2020

Redundant constraints may cause great difficulties during the numerical simulation, when solving the differential algebraic equations (DAEs). The article presents a regularization method based on optimization form of the Gauss principle of least constraint and the Udwadia and Kalaba (UK) method, which expresses the solution of the dynamic motion in an explicit expression. Compared with Lagrange method, the proposed method does not need to solve the Lagrange multipliers any more for the complex multibody mechanical systems. In the end, a numerical example is given to illustrate that the proposed method not only has the ability to handle the problems with redundant constraints, but also has higher accuracy and keep a stable constraint violation level than the traditional methods.
New theoretical system of physics in the 21st century
Authors: Zhou Jiang Hua
Published: October 2020

In 2000, the author published a new discovery about the same-sex charge produced by friction of the same substance at the ninth electrostatic academic conference of Chinese physical society. For this important new experimental discovery, the author puts forward a new understanding of “positive and negative charges” and finds a new theory to explain all electrostatic effects. Based on the subversive new understanding of “matter”, “entity” and “heat energy”, a new understanding of “particle charge dynamic atomic model” is initiated. It is clarified that the relationship between “entity” and “heat energy” is the root of the existence of gravitation and repulsion between matter, The law of equilibrium distance between gravity and repulsion is put forward. This paper reveals the causes of the formation of the earth’s gravity and many phenomena of attraction and repulsion force in the universe and so on. In the fields of gravitational field, magnetic field, electric field and so on, a series of important scientific problems have been revealed! The establishment of the new theoretical system provides a new vision for solving “all physical problems”! The new theoretical system consists of six parts: the first part introduces the reasons for the establishment of the “new theoretical system”, the second part proposes a new basic epistemology of the material world, the third part is a new epistemology of the gravitational repulsion field, the fourth part is a new epistemology of the magnetic field, and the fifth part is a new epistemology of the electric field, and the sixth part expounds the scientific significance of the new theoretical system. Starting from a new perspective of the basic composition of “entity” and “heat energy” in the material world, this paper makes a new understanding of matter, entity, heat energy, atom, element, gravity, repulsion, magnetic field and electric field, Established 21st century physics new theoretical system, Material world: “entity” and “heat energy” constitute “unified field theory”. Scientific research needs a new vision to expand the subjective human thought’s understanding of the objective nature. The establishment of this new theoretical system may lead to a new physics revolution in the 21st century.
The Research of Wind Power Project Company’s Engineering Management System
Authors: Cai Hualong , Xie Wanchao , Lin Dongliang
Published: October 2020

By analyzing the process of construction engineering management of Wind power project company, we can abstract the core professional work, which includes budgets, bits, contracts, schedules, quality, safety, finance, machine management and more contents. Combined with the organizational structure of project companies, linked with the process of core professional work, to design the hardware and software structure of construction engineering management system.
Image classification based on RESNET
Authors: Liang Jiazhi
Published: October 2020

at present, neural networks are becoming more and more complex, from several layers to dozens of layers or even more than 100 layers. The main advantage of deep network is that it can express very complex functions. It can learn features from different levels of abstraction, such as edge features at lower levels and complex features at higher levels.However, the use of deep networks is not always effective, because there is a very big obstacle - the disappearance of gradients: in very deep networks, gradient signals tend to approach zero very quickly, which makes the gradient descent process extremely slow.Specifically, in the process of gradient descent, the weight matrix product operation must be carried out in every step of back propagation from the last layer to the first layer, so that the gradient will drop exponentially to 0.(in rare cases, there is the problem of gradient explosion, that is, the gradient grows exponentially to the overflow in the process of propagation). Therefore, in the process of training, it will be found that with the increase of the number of layers, the rate of gradient decrease increases.Therefore, by deepening the network, although it can express any complex function, but in fact, with the increase of network layers, we are more and more difficult to train the network, until the proposal of residual network, which makes it possible to train deeper network[1].
Research on Coordinated Optimization of Active and Reactive Power in Active Distribution Network
Authors: Wu Xiaomeng , Li Chong
Published: October 2020

Traditional optimization for distribution network usually uses reactive power optimization to ensure the safe operation of the distribution network, and uses the distributed power and various adjustable resources of active power adjustment to ensure the economic operation of the distribution network. However, in the distribution network, the impedance ratio of the line is large and the coupling of active and reactive power is strong. Unilateral active or reactive optimization for distribution network is not comprehensive. In addition, the uncertainty of Distributed Generation and load poses a great challenge to optimization for active distribution network, the control strategy formulated by traditional deterministic optimization might inaccurate. In this paper, the mathematical model of active and reactive power coordinated optimization for active distribution network is given. Various algorithms dealing with the uncertainty of distribution are introduced, and advantages and disadvantages of various algorithms are analysed.
Infrared and Visible Image Fusion Based on Spatial Convolution Sparse representation
Authors: Shao Luling , Wu Jin , Wu Minghui
Published: October 2020

In the traditional sparse representation based infrared and visible image fusion method, the detail information is not able to be effectively extracted, resulting in the decrease of infrared target intensity and the blurry of visible background information. In order to solve the above issue, a new image fusion method based on spatial convolution sparse representation is proposed. Firstly, a spatial convolution sparse representation is used to perform two-scale decomposition of infrared and visible images by introducing a gradient regularization, and the detail and intensity information are extracted effectively from the source images. Then, the weighted average rule and the maximum selection rule are used to fuse the base layer and detail layer images, respectively. Finally, the fusion image is constructed. Experimental results illustrate that the proposed method is superior to the traditional fusion method based on sparse representation.
Prototypical Network for Radar Image Recognition with Few Samples
Authors: Liu Diyang , Gao Xunzhang , Shen Qinmu
Published: October 2020

At present, deep learning has surpassed humans in recognition tasks, but its performance strongly depends on sufficient training samples. When the training samples are extremely insufficient, overfitting also will damage the performance of network, despite the use of fine-tuning methods. One-shot learning (OSL) is proposed to overcome the difficulties of training neural networks while having almost no samples, which is a common situation in radar image recognition. This paper introduced OSL into recognition of some radar targets whose labelled images are seriously limited, and proposed an OSL method with prototypical networks based on the assumption that functions of the network trained with auxiliary samples also affects samples to be identified. The method of this paper involves image preprocessing, building of linearly separable feature space and feature vector clustering. Experiments on MSTAR dataset show that the performance of our method is better than deep transfer learning when the training samples in the target domain are seriously deficient.
Malicious vehicle node detection mechanism based on repeated game and trust evaluation in VANET
Authors: Zhu Yatao , Wang Yongli
Published: October 2020

In order to solve the problem of malicious vehicle nodes attack in VANET system and improve the security of VANET communication, the paper proposes a method of malicious vehicle nodes detection based on repeated games and trust evaluation. First of all, according to vehicle nodes communicating, a repeated game model is established to generate vehicle nodes revenue by punishing attack behavior nodes and rewarding normal behavior nodes. Secondly, a trust evaluation mechanism is introduced to convert vehicle nodes revenue into nodes trust value. Finally, the optimal dynamic threshold is calculated through multiple iterations, comparing and analyzing nodes trust value and dynamic threshold to screen out the malicious vehicle nodes. Simulation experiments show that this mechanism improves the detection rate of malicious nodes and reduces the error detection rate, effectively isolates malicious vehicle nodes according to the change of node trust value, and improves the security of VANET communication.
Application of Hyperspectral Images and Spectral Features of Yolks in Egg Freshness Detection
Authors: Huang Shiqi , Pu Xuewen , Luo Peng
Published: October 2020

The detection of egg freshness is an important basis and means to obtain the effective value of eggs. In order to more effectively and reasonably classify and monitor the quality of eggs, a new egg quality identification method based on the hyperspectral image data of egg yolk and its spectral characteristics data is proposed. In this method, the spectral and hyperspectral data of the raw yolk and the boiled yolk are obtained by using a spectrometer and a hyperspectral imager, respectively. By analyzing different spectral properties, building a relationship model between each other, combining with different results, the new proposed method has achieved the purpose of identifying the freshness of eggs. The test experiments were carried out with different batches eggs of the same type. The results show that the method proposed in this paper can detect the freshness of eggs, and can provide new ideas and references for egg quality classification and detection.
Local path planning for unmanned surface vehicle with improved artificial potential field method
Authors: Xiao Ma , Zuan Lin , Song Ruiyin
Published: October 2020

Aiming at the drawbacks of traditional artificial potential field method in local path planning for USV (unmanned surface vehicle), an improved artificial potential field method is proposed. By improving the gravitational potential field model and restraining the distant gravitational potential field, the problem of USV colliding with obstacles is solved. In the repulsion field model, the influence factors such as relative position and relative velocity are introduced to reduce the repulsion potential field intensity of the obstacle near the target, so as to solve the problem of goal nonreachable with obstacle nearby. The regulation mechanism of random perturbation potential energy is introduced to solve the problem that it is difficult to move at local minimum points. The rationality and superiority of the proposed improved artificial potential field method are verified by simulation and comparison experiments.
A low illumination image enhancement algorithm based on adaptive fractional differentiation
Authors: Wang Liangyan , Zhan Xiaoyi , Wang Chunling , Chen Zihong , Xia Yunfei
Published: October 2020

Using fixed order fractional differential for image enhancement, some regions of the image may not achieve the desired enhancement effect. According to the characteristics of human vision and low illumination image, an adaptive order fractional differential enhancement algorithm is proposed. Three different differential orders are selected for enhancement, and one of them is adaptively selected for each pixel according to the comparison results of gradient values. The experimental results show that the adaptive order can not only enhance the image with high gradient value such as the edge, but also reduce the noise interference in the flat area, which has better visual effect than fixed order enhancement.
Study on 3D Pore Label of Porous Materials Based on CT Images
Authors: Liu Zhidong
Published: October 2020

Microscopic pore structure is one of the important factors affecting macro porous materials physical properties, pore structure research for characterization of physical properties of porous materials is of great significance. In order to study the three-dimensional parameters of porous materials in each pore structure, such as pore size, volume, specific surface area, fractal and connectivity, it is necessary to label each pore structure in the three-dimensional structure. Two-dimensional CT image sequences in porous material as the research object, three-dimensional target marking algorithm is proposed. The sequence images using median filter algorithm to remove noise, through the automatic threshold segmentation algorithm, get the binary image. The boundary information of each pore is computed by Using the algorithm of two-dimensional multi-target label in each layer image. The 3D pore structure is labelled by the calculation of the projection relationship between the targets in the tomography image. The labelled result of pore structure is verified by single and whole reconstruction with marching cube algorithm. Results show that the porous three-dimensional pore structure was marked accurately, which lays a foundation for the calculation of 3D pore structure parameters.
Estimation of SPAD value in tomato leaves by multispectral images
Authors: Ding Yongjun , Zhang Jingjing
Published: October 2020

To improve the prediction accuracy of tomato chlorophyll content based on multispectral images, three preprocessing methods that can weaken illumination influence, i.e., self-adaptive gamma correction, multiscale Retinex and reflectance reconstruction, are compared and analyzed, and corresponding estimation models for the tomato Soil-Plant Analysis Development (SPAD) value are established. The correction coefficients are set according to the deviations between the grayscale values of the pixels in the highlighted and shaded areas and the average grayscale values in the area of uniform illumination to realize the self-adaptive gamma correction. The SPAD estimation model is constructed by the corrected image, with input parameters of nir, RVIb,g, RVIg,nir, RVIr,nir, NDVIr,g, and NDVIb,r, and the Rc2 and Rv2 of the model are 0.87 and 0.8, respectively. The original image is convolved with three different Gaussian functions to obtain a multiscale Retinex corrected image, and the SPAD estimation model is constructed. The input parameters are b, RVIr,g, RVIr,nir, RVIg,b, RVIg,nir, RVIb,nir, and NDVIr,g, and the Rc2 and Rv2 of the model are 0.91 and 0.84, respectively. The accuracy of the above two models depends on the selection of the corrected gamma value and the convolution kernel, and improper selections could seriously affect the accuracy of the model. For the SPAD value estimation model based on the reflectance reconstruction, its input parameters are nir, RVIg,nir, RVIr,g, NDVIg,b, NDVIr,nir, and NDVIb,r, and the Rc2 and Rv2 of the model are 0.90 and 0.88, respectively. The preprocessing procedure is simple, and the universality is high, making it suitable for the application of the digital field management of the crop.
Stamen movement detection of Commelina purpurea based on feature matching
Authors: Gui Chengbo , Jiang Haibo , He Jin , Tang Dan
Published: October 2020

The stamen movement is very important to reproduction of plant. This paper presents a feature-matching-based method to detect stamen movement of Commelina Purpurea using image processing. The regions of stamen were firstly extracted by image segmentation using thresholding. Then, the area discrimination factor of each stamen region was calculated to judge whether these stamens were adhered or not, if such adhesion did exist, the adhered stamens were segmented by watershed algorithm. After that, feature detection and matching were carried out between two adjacent frames in the image sequence in order. Then, the slope and distance statistics between the matching feature points are maded to further optimize the matching results and figure out the matching relation of different stamens in the two frames. Finally, through the matching result of different stamens in consecutive frame images, the moving trajectory of the stamens was obtained. The empirical results show that, this method can accurately segment the adhered stamens and acquire stamen trajectory of Commelina Purpurea.
Calibration method of simulation data of virtual GPS and truth value in real world
Authors: Chen Chen , Zhang Dongze , Mei Junyu , Zhao Yuliang , Chen Rongjie
Published: October 2020

At present, the complexity of the research and development process of the intelligent connected vehicle and the diversity of research methods increase the difficulty of establishing, integrating and verifying of virtual simulation experiments. In view of the deviation of the virtual vehicle sensor in the simulation experiment to the restoration of the real environment, this paper proposes to use the multi-point positioning method for data calibration, use the least square method to estimate the unknown point position in complex situations, and according to the error size after calibration, specific evaluation criteria are given. Finally, the scene verification and simulation evaluation of the calibration method of the GPS simulation data in the virtual environment and the truth value in the real world were carried out. The results show that this method effectively improves the restoration degree of the virtual simulation sensor to the real environment.
A Time Dependent Process Zone Model for Slow Crack Growth of Polyethylene Pipe Material
Authors: Liu Yijiang , Li Yan , Liu Xiu , Luo Wenbo , Yang Bo , Li Maodong
Published: October 2020

Polyethylene (PE) pipe is widely used in water supply and gas transportation engineering. Its fracture behavior is very important for the safe operation of the pipeline. The objective of this work is to simulate the slow crack growth (SCG) process of PE pipe material via a time dependent crack-tip process zone model. To achieve this end, the crazing damage caused by stress concentration at crack tip of PE material is taken into account, the stress on the bulk/craze interface layer is supposed to be uniformly distributed due to the micro necking mechanism of the layer, and a linear crack growth kinetics is used. In order to describe the delay characteristics of the fracture process of PE materials, the fracture surface energy is considered as an exponential decay function of time, which is attributed to the creep damage of the craze fibrils. A simulation algorithm of the proposed process zone model is suggested using iterative method. The model is verified by comparing the simulation with the discontinuous SCG behavior reported in the literature.
Research on Hydrodynamic Characteristics of Wave Energy Power Plant
Authors: Huang Yu
Published: October 2020

Ocean energy is a kind of high-quality renewable energy. Therefore, it will not be exhausted and has attracted wide attention. China’s coastline is 18,000 kilometers long, so China has abundant ocean energy. In order to realize the utilization of wave energy, the research on wave energy power generation technology has never stopped. Wave energy generation refers to the use of wave motion to generate electricity, first converting wave energy into intermediate energy through a conversion device, and then converting intermediate energy into electrical energy. Combining with China’s actual situation, China’s research on wave energy devices mainly has three types: oscillating water column, pendulum, sink and float. Due to the huge difference in sea conditions and the characteristics of China’s offshore waves with short periods and relatively low energy density, wave energy conversion devices must be independently developed, and hydrodynamic behavior research is the basic work. In this paper, through the theoretical analysis and numerical calculation research methods, the hydrodynamic behavior characteristics of the wave energy conversion device are studied, and the simulation analysis is performed using the hydrodynamic software AQWA.
Structural and elastic properties of WSe2: first-principles calculations
Authors: Li Jihong , Jia Liping , Zheng Xingrong , Peng Changning , Fu Xijing
Published: October 2020

By using the first principle’ density functional theory, we calculated the structural and elastic properties of WSe2 crystals under different pressures. The results show that the compressibility of WSe2 in the c-direction is much greater than that in the a-direction. The results of the elastic constants reveal that WSe2 is mechanically stable under pressure 0 GPa to 50 GPa. The calculation results of elasticity-relevant properties show that the WSe2 crystal is a brittle material and is solid with interatomic forces.
Numerical Study of Mechanical Properties of Composite Solid Propellant with Initial Defects
Authors: Wang Jiaxiang , Qiang Hongfu , Wang Zhejun , Li Shiqi
Published: October 2020

In order to study the effect of initial interface defects and initial void defects on the macro tensile mechanical properties of composite solid propellant, based on the Python script, the particle filling model of composite solid propellant with meso pores and interface defects was established in ABAQUS. Firstly, zero thickness cohesive elements were embedded at the adjacent elements of the matrix and the particle/matrix interface, and the traction separate law was used to simulate the fracture failure of composite solid propellant. Then, the influence of different shapes, porosity and interface defect ratio on the elastic modulus and tensile strength of composite solid propellant was studied. Accordingly, the relationship between the initial damage of the composite solid propellant and the porosity and interface defects was established. Morever, the initial damage surface of the composite solid propellant was depicted. Results showed that the initial damage of polygon filling model is larger than that of circular particle filling model under the same initial defect condition; The elastic modulus of composite solid propellant decreases linearly with the increase of porosity and interface defect ratio; The tensile strength of composite solid propellant decreases linearly with the increase of interface defect ratio, and decreases logarithmically with the increase of porosity.
Flow Force of Pressure Independent Control Valve with Different Valve Core Structural
Authors: Fan Y L , Lei Y , Zhang J W , Wang J , Li Z
Published: October 2020

Aiming at the problem of hydraulic and thermal imbalance in variable flow heating and cooling systems, based on the computational fluid dynamics method, the 3D model of pressure independent control valve under different control valve core structure is established. The kinetic equation of valve core were established by using the valve core movement. The influence of different control core structure on valve Properties under transient pressure was studied, the distribution of fluid force, and pressure on valve core are obtained. The results show that, under the same flow characteristics, there are certain unbalanced forces in different valve core structure under different pressure differences, the fluid force distribution of the valve core is different, with a maximum value difference of 140%. Reasonable selection of different valve core structures for different working conditions can effectively improve the properties of the valve.
Performance Research on Bi-directional Tilting Pad Thrust Bearing Considering the Verticality Error of Thrust Plate
Authors: Chen Runlin , Han Qin , Wang Xingzhao , Cui Yahui , Liu Kai
Published: October 2020

In order to improve the axial stiffness and its controllability of the CNC machine tool spindle system, a bi-directional tilting pad thrust bearing is used instead of the hydrostatic thrust bearing to bear the axial load. Due to the processing and installing, there must be a certain verticality error between the thrust plate and rotor axis. The lubrication model of the thrust bearing considering the verticality error is established in this paper. The Reynolds equation is solved by FDM (finite difference method), and the key performance data of the bidirectional tilting pad thrust bearing under rated conditions are obtained, including eccentricity, minimum film thickness, maximum temperature rise and axial stiffness, etc. The variation of performance parameters such as film thickness, temperature rise and stiffness of thrust bearing with different working conditions are mainly studied. The maximum allowable verticality errors in the whole working condition range of load and speed are given. According to the requirements of film thickness and temperature rise, the thrust bearing clearance is optimized based on the comprehensive consideration of lubrication performance and dynamic performance, and the allowable ranges of clearance under different verticality errors is analyzed. This research provides theoretical guidance for the design and manufacture of tilting pad thrust bearings used for the CNC machine tool spindle system.
Optimization and Design of Regenerative Cooling Channel for Scramjet Engine
Authors: Gao Feng , Zhang Qian , Xiao Hongyu , Zhang Chengtao , Xia Xuefeng
Published: October 2020

In this paper, the optimization model and numerical calculation verification model of the regenerative cooling channel structure of the scramjet engine are established, and the structural parameters of the regenerative cooling channel of the scramjet engine are optimized and numerically verified. The results show that the established optimization model of the regenerative cooling channel structure of the scramjet engine can meet the design requirements; after the structure optimization, the wall temperature change trend is basically the same as the original design change trend, and the overall temperature is low; the central flow calculated by the optimized configuration calculation, but the pressure loss of kerosene in the cooling channel is small. The oil temperature and convection heat transfer coefficient are large; the inner wall and fins of the optimized configuration are thinner, the channel height is higher, and the width is narrower, which can effectively increase the convection heat transfer efficiency of the cooling channel, which can ensure that the material temperature is not Exceeding its maximum allowable temperature can make the pressure loss relatively low.
Researches on plateau flight trajectory characteristics of Non-controlled rotating projectile
Authors: Liu Yuwen , Duan Yanan , Jiang Ming , Cai Hongtu
Published: October 2020

The projectile dispersion in the plateau area has increased in various degree and decreased of the fire precision. The analysis shows that it has a considerably relations with altitude and the changes of trajectory characteristics associated with altitude. In order to reflect the change law of external ballistics trajectory characteristic in the plateau area clearly. Simulate compute the trajectory data and changes of projectile attitude in different altitude accord to trajectory model. These research findings will lay a foundation for further research on projectile precision in the plateau.
Topological Lightweight Optimization Simulation on EMU Luggage Rack Bracket
Authors: Sun Linfeng , Wang Bingsong
Published: October 2020

Basing on unite simulation method with INSPIRE and HYPERMESH, topological lightweight optimization on coach luggage rack bracket structure of China Standard EMU train had been executed. By comparing the simulation results with the test data, accuracy of the computational models had been verified. It was proved that the modified luggage rack bracket structure would have better mechanical performance and reach the goal of lightweight at the same time.
An optimization method of separation parameters for pico-satellite by minimizing external moment
Authors: Liu Yuchen , Teng Lai , Jin Zhonghe
Published: October 2020

In this article, a direct and key factor which affects separation parameters of satellite-rocket separation mechanism called optimization method of minimizing external moment is introduced. By changing the positions of elastic launch devices, popping process is effectively controlled. This optimization method is proved by ground test which can offset gravity, and it particularly adapts to the fixed and non-stable status elastic parameters, the distribution of all kinds of elastic devices and bias aircrafts which are hard to make the correction. The method has successfully applied to prediction and optimization for the separation of “Zhejiang University BJ Pico-satellite”. It is widely used now in practice with its easy operation.
Chaotic motion of time-delay fractional order financial dynamic system of single sliding mode control
Authors: Dong Jun , Xiao Yao , Ma Hu , Zhang Guangjun
Published: October 2020

In this paper, the equations of time-delay fractional order financial dynamic system are studied. Firstly, the dynamic characteristics of the time-delay fractional order financial system with are analyzed. Secondly, the attractor state change of the time-delay fractional order financial system induced by disturbance is studied. By adding specific uncertainties and disturbances to the specified state variables of the system, the attractor of the system is induced to change. Finally, the classical integral sliding mode control method is used to design a single controller to control the time-delay fractional order financial system from chaos to fixed point, and the feasibility and robustness of the control scheme have been proved theoretically and verified by the simulation.
Simulation research of the Pulsating Excitation and Vibration Response of Propeller in Wake Field
Authors: Peng W C , Tan Y H
Published: October 2020

The pulsating excitation and vibration response of a highly skewed propeller, running in wake field, was studied by the Fluid-Solid Interaction (FSI) simulation. Coupling calculation of elastic propeller was realized on ANSYS-CFX modules based on the CFD/FEM FSI method, and the rigid results were compared. The results show that, the pulsating thrust of the elastic propeller considering FSI effect has the same low frequency peak as the rigid except the low frequency elastic peak (the first-order natural frequency of propeller), and the low-frequency broadband force amplitude of the elastic propeller is an order of magnitude higher than the rigid. In addition to the correlation between blade frequency and shaft frequency, the propeller also has obvious vibration response at the lower natural frequency. The results are significant to the prediction and control of propeller vibration response.
AOCS General Architecture Design for SVOM Satellite
Authors: Liu Shuang , Li Jinsong , Qin Genjian , Li Dong , Fang Yuxin
Published: October 2020

SVOM mission is a Sino-French cooperation satellite which requires high attitude accuracy and platform stability. In order to guarantee the 100s’ observation time, the Relative Pointing Error is required to up to 0.8arcsec/100sec (3 sigma). The Attitude and Orbital Control System (AOCS) is a key element for SVOM mission because of this severe pointing performance requirement. This article describes the AOCS general architecture design for SVOM satellite. First, the main requirements are presented. Second, the key hardware is introduced, including a newly designed sensor, named Fine Guidance Sensor. At last, the AOCS modes design and transfer logic are given.
Fabrication and characterization of a thick, viable bi-layered stem cell-derived surrogate for future myocardial tissue regeneration
Authors: Pretorius Danielle , Kahn-Krell Asher M , LaBarge Wesley C , Lou Xi , Kannappan Ramaswamy , Pollard Andrew E , Fast Vladimir G , Berry Joel L , Eberhardt Alan W , Zhang Jianyi
Published: October 2020

Cardiac tissue surrogates show promise for restoring mechanical and electrical function in infarcted left ventricular (LV) myocardium. For these cardiac surrogates to be usefulin vivo, they are required to support synchronous and forceful contraction over the infarcted region. These design requirements necessitate a thickness sufficient to produce a useful contractile force, an area large enough to cover an infarcted region, and prevascularization to overcome diffusion limitations. Attempts to meet these requirements have been hampered by diffusion limits of oxygen and nutrients (100–200 µm) leading to necrotic regions. This study demonstrates a novel layer-by-layer (LbL) fabrication method used to produce tissue surrogates that meet these requirements and mimic normal myocardium in form and function. Thick (1.5–2 mm) LbL cardiac tissues created from human induced pluripotent stem cell-derived cardiomyocytes and endothelial cells were assessed,in vitro, over a 4-week period for viability (<5.6 ± 1.4% nectrotic cells), cell morphology, viscoelastic properties and functionality. Viscoelastic properties of the cardiac surrogates were determined via stress relaxation response modeling and compared to native murine LV tissue. Viscoelastic characterization showed that the generalized Maxwell model of order 4 described the samples well (0.7 <R2< 0.98). Functional performance assessment showed enhanced t-tubule network development, gap junction communication as well as conduction velocity (16.9 ± 2.3 cm s−1). These results demonstrate that LbL fabrication can be utilized successfully in creating complex, functional cardiac surrogates for potential therapeutic applications.
A new example of the effects of a singular background on the zeta function
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Authors: Falomir Horacio , Liniado Joaquín , Pisani Pablo
Published: October 2020

To motivate our discussion, we consider a 1 + 1 dimensional scalar field interacting with a static Coulomb-type background, so that the spectrum of quantum fluctuations is given by a second-order differential operator on a single coordinate r with a singular coefficient proportional to 1/r. We find that the spectral functions of this operator present an interesting behavior: the ζ function has multiple poles in the complex plane; accordingly, logarithms of the proper time appear in the heat-trace expansion. As a consequence, the ζ function does not provide a finite regularization of the effective action. This work extends similar results previously derived in the context of conical singularities.
The Effect of Mechanochemical on The Formation of Calcium Titanate (CaTiO3) Prepared by High Energy Milling
Authors: Fauzi Fiqhi , Muhammad Habieb Alvin , Noviyanto Alfian , Kusumaningrum Retno , Sukmarani Galuh , Uswah Dien Muhammad Edela , Jovanka Widodo Valleta , Calista Amalia Diva , Aryanto Didik , Taufiqu Rochman Nurul
Published: October 2020

Single-phase calcium titanate (CaTiO3) was successfully synthesized by mechanical milling and the solid-state reaction of CaCO3 and TiO2. The speed of high energy ball milling was 700 rpm with the ball and jar were made from stainless steel. The milling time and ball to powder ratio was 10 h and 50 h, respectively. After milling for 10 h, the mixed powder of CaCO3 and TiO2 experienced heavy milling, which indicated by the average particle size before and after milling was > 1 µm and 85.56 ± 35.62 nm, respectively. Furthermore, the XRD pattern of milled powder revealed the disappearance of CaCO3 peaks and a considerable reduction of TiO2 peaks after milling for 10 h. Moreover, the presence of CaTiO3 peaks in the milled powder was noticeably detected in the XRD pattern, showing the mechanical alloying of CaCO3 and TiO2 was occurred. The milled powder was calcined at 800, 900 and 1000°C for 2 h. The results showed the formation of a single phase of CaTiO3 after calcination at any temperatures. However, the samples indicated the presence of Fe2O3, which from the milling media. The presence of impurities after milling is inevitable due to friction between ball and jar. Further study is needed to obtain the optimum condition of mechanical milling to minimize the contamination.
Distribution of Hardness, Surface Roughness and Wettability of AISI 316L Induced by Shot Peening with Different Duration and Shooting Distance
Authors: Tri Iswanto Priyo , Akhyar  , Faqihudin Arif , Muhammad Sadida Hizba
Published: October 2020

A research is conducted to analyze the effect of shot peening on distribution of hardness, surface roughness, and wettability of AISI 316 L. The shot peening process was performed on the surface of a 316L stainless steel sample with a shooting duration of 2, 4, 15, and 30 minutes, using a 0.4 mm diameter steel ball with a hardness of 40-50 HRC, the pressure of compressor held constant at 8 bar with nozzle diameter 5 mm, and the distance between the nozzle and the surface sample is 6 cm and 12 cm for each shooting duration. The results show that the shot peening can change the surface roughness. The closer the distance and the longer the duration of shot peening will reduce the surface roughness. Surface hardness increase with increasing of shooting duration and hardness distribution rate declines as the farther the distance from the surface of the shot peening.
Clean Water Programs In Oefafi Village, Kupang, Nusa Tenggara Barat
Authors: Yoga Santoso Prasetya , Erland Hamzah Radja , Pratiwi Erma
Published: October 2020

Oefafi is one of the driest places in Indonesia and community experiences water shortages. They need to walk up to 1-2 km to get a water source due to the unavailability of water. There are many aid programs in the Oefafi but it is unsuccessful. They were not used maximally by the community and the level of community involvement was low. Jaka Perkasa Citra Cemerlang Foundation (JPCC) is a non-profit organization. This foundation empowers the community through the clean water programs in Oefafi. The research objective is to find out how JPCC foundation’s communication strategy in empowering the local community through the clean water program. It also focuses on the supporting factors as well as the inhibiting factors in implementing community empowerment communication strategies. This research uses a qualitative approach with a case study method. The results of the study showed the success case of community empowerment in Oefafi. Empowerment by JPCC Foundation already showed an active participation. The communication strategy carried out successfully to trust in the community so that the community has the awareness and willingness to change. Although there are some communities who refuse to be empowered due to the character of people.