bluuebunny/crossref_metadata_2025 huggingface dataset:
Rolling bearing performance degradation assessment based on singular value decomposition-sliding window linear regression and improved deep learning network in noisy environment
Authors: Dong Shaojiang , Li Yang , Zhu Peng , Pei Xuewu , Pan Xuejiao , Xu Xiangyang , Liu Lanhui , Xing Bin , Hu Xiaolin
Published: November 2021

It is difficult to evaluate the degradation performance and the degradation state of a rolling bearing in noisy environment. A new method is proposed to solve the problem based on singular value decomposition (SVD)-sliding window linear regression and ResNeXt–multi-attention mechanism’s deep neural network (RMADNN). Firstly, the root mean square (rms) gradient value is calculated on the basis of rms based on SVD and sliding window linear regression, which is used as the rolling bearing performance degradation indicator in noisy environment. Secondly, the degradation state of the rolling bearing is divided by the rms gradient. Thirdly, for the deep learning network model, the soft attention mechanism is introduced into the bidirectional long short-term memory network to extract more important and deep fault features. At the same time, the ResNeXt layer is added into the convolutional neural network to extract more fault features and merge them through multi-scale grouped convolution. The hybrid domain attention mechanism (HDAM) is introduced after the ResNeXt layer. The HDAM can screen out more important features from the output features of the ResNeXt in the two dimensions of channel and spatial which demonstrates the improved deep learning network of the RMADNN. Finally, the labeled data set is input into the improved model for training, and the Softmax classifier is used to identify the life degradation state of the rolling bearing. Through the verification of multiple test data sets, the results show that the method proposed in this research is very effective on the rolling bearing performance degradation assessment.
Carbon monoxide gas sensor based on an α-Fe2O3/reduced graphene oxide quantum dots composite film integrated Michelson interferometer
Authors: He Sijie , Liu Yushan , Feng Wenlin , Li Bangxing , Yang Xiaozhan , Huang Xinyue
Published: November 2021

A carbon monoxide (CO) sensor based on a Michelson interferometer combined with α-Fe2O3/reduced graphene oxide quantum dots (rGOQDs) composite film is proposed and fabricated. First, a waist-enlarged taper is formed between the single-mode fiber (SMF) and the no-core fiber (NCF), then the other end of the NCF is spliced with a section of thin-core fiber (TCF). The end of the TCF is coated with a layer of silver film to enhance the reflection. Thus, a Michelson interferometer comprising SMF–NCF–TCF is formed. The α-Fe2O3/rGOQDs composite film is deposited on the outside surface of the TCF. The specific adsorption of CO by the composite film leads to a change in the sensor’s effective refractive index, realizing the detection of CO. The results show that the interference intensity of the monitoring valley decreases with increase in the concentration of CO. The sensitivity of the sensor is 0.057 dBm ppm−1, the detection limit of the sensor is 105 ppb and the response time and recovery time are 70 s and 100 s, respectively. The sensor has the advantages of high sensitivity, high selectivity and simple structure, and it is expected to be used for the detection of low concentrations of CO gas.
Research on plasma electron density distribution based on microwave diffraction
Authors: Zhao Chengwei , Li Xiaoping , Liu Yanming , Liu Donglin , Sun Chao , Ma Gelu , Tian Lishan , Bao Weimin
Published: November 2021

In this paper, a noncontact plasma microwave diffraction measurement method is proposed, which can obtain the electron density at different diameters of the cylindrical plasma. There is a lot of diffraction when a non-focused antenna is used to transmit plasma. As is well known, when the frequency of the incident microwave is lower than the characteristic frequency of the plasma, the microwave cannot be transmitted through the plasma, so this interface can be regarded as a metal. According to the microwave diffraction of the plasma, the size of the plasma corresponding to the characteristic frequency can be obtained. Furthermore, by sweeping the incident electromagnetic wave, the size of plasma with different characteristic frequencies can be obtained, and the distribution of electron density can be obtained. To verify the method, a cylindrical plasma was measured by microwave diffraction, in which the electron density of the plasma column gradually decreased along with the increase in radius. According to the diffraction of the plasma column at different frequencies, the distribution of the electron density along the diameter is obtained. In order to verify the distribution results, a Langmuir probe was used for diagnosis in a similar propagation path. The two diagnosis methods have a diagnosis deviation of less than 60%. Finally, the accuracy of diffraction diagnosis is given, and the next step to improve the accuracy of the diagnosis is given. In extremely high temperature, regular shape, nonuniformly distributed plasma, microwave diffraction diagnosis has a wider range of applications.
A search for the variation of speed of light using galaxy cluster gas mass fraction measurements
Authors: Mendonça I.E.C.R. , Bora Kamal , Holanda R.F.L. , Desai Shantanu , Pereira S.H.
Published: November 2021

In this paper, we implement a new method to test the invariance of the speed of light (c) as a function of redshift, by combining the measurements of galaxy cluster gas mass fraction, H(z) from cosmic chronometers, and Type-Ia supernovae (SNe Ia). In our analyses, we consider both a constant depletion factor (which corresponds to the ratio by which the cluster gas mass fraction is depleted with respect to the universal baryonic mean) and one varying with redshift. We also consider the influence of different H
0 estimates on our results. We look for a variation of c, given by c(z) = c
0(1+c
1
z). We find a degeneracy between our final results on c variation and the assumptions on the gas mass fraction depletion factor. Most of our analyses indicate negligible variation of
the speed of light.
Reconciling hints on axion-like-particles from high-energy gamma rays with stellar bounds
Authors: Gautham A.P. , Calore Francesca , Carenza Pierluca , Giannotti Maurizio , Horns Dieter , Kuhlmann Julian , Majumdar Jhilik , Mirizzi Alessandro , Ringwald Andreas , Sokolov Anton , Stief Franziska , Yu Qixin
Published: November 2021

It has been recently claimed by two different groups that the spectral modulation observed in gamma rays
from Galactic pulsars and supernova remnants can be due to conversion of photons into ultra-light axion-like-particles (ALPs) in large-scale Galactic magnetic fields.
While we show the required best-fit photon-ALP coupling, gaγ
 ∼ 2 × 10-10 GeV-1, to be consistent with constraints from observations of photon-ALPs mixing in vacuum, this is in conflict with other bounds, specifically from the CAST solar axion limit, from the helium-burning lifetime in globular clusters, and from the non-observations of gamma rays in coincidence
with SN 1987A. In order to reconcile these different results, we propose that environmental effects in matter would suppress the ALP production in dense astrophysical plasma, allowing to relax previous bounds and make them compatible with photon-ALP conversions in the low-density Galactic medium. If this explanation is correct, the claimed ALP signal would be on the reach of next-generations laboratory experiments such as ALPS II.
Generation of elliptical isolated attosecond pulse from oriented

H2+

in a linearly polarized laser field
Authors: Xing Yun-He , Zhang Jun , Huo Xiao-Xin , Xu Qing-Yun , Liu Xue-Shen
Published: November 2021

We investigate the ellipticity of the high-order harmonic generation from the oriented

H
2
+

exposed to a linearly polarized laser field by numerically solving the two-dimensional time-dependent Schrödinger equation (2D TDSE). Numerical simulations show that the harmonic ellipticity is remarkably sensitive to the alignment angle. The harmonic spectrum is highly elliptically polarized at a specific alignment angle θ = 30°, which is insensitive to the variation of the laser parameters. The position of the harmonic intensity minima indicates the high ellipticity, which can be attributed to the two-center interference effect. The high ellipticity can be explained by the phase difference of the harmonics. This result facilitates the synthesis of a highly elliptical isolated attosecond pulse with duration down to 65 as, which can be served as a powerful tool to explore the ultrafast dynamics of molecules and study chiral light–matter interaction.
Manipulating vortices in F = 2 Bose–Einstein condensates through magnetic field and spin–orbit coupling
Authors: Zhu Hao , Yin Shou-Gen , Liu Wu-Ming
Published: November 2021

Weinvestigate the vortex structures excited by Ioffe–Pritchard magnetic field and Dresselhaus-type spin–orbit coupling in F = 2 ferromagnetic Bose–Einstein condensates. In the weakly interatomic interacting regime, an external magnetic field can generate a polar-core vortex in which the canonical particle current is zero. With the combined effect of spin–orbit coupling and magnetic field, the ground state experiences a transition from polar-core vortex to Mermin–Ho vortex, in which the canonical particle current is anticlockwise. For fixed spin–orbit coupling strengths, the evolution of phase winding, magnetization, and degree of phase separation with magnetic field are studied. Additionally, with further increasing spin–orbit coupling strength, the condensate exhibits symmetrical density domains separated by radial vortex arrays. Our work paves the way to explore exotic topological excitations in high-spin systems.
Validation of a full-plasma integrated modeling approach on ASDEX Upgrade
Authors: Luda T. , Angioni C. , Dunne M.G. , Fable E. , Kallenbach A. , Bonanomi N. , Lunt T. , Schneider P.A. , Siccinio M. , Tardini G. , the ASDEX Upgrade Team  , the EUROfusion MST1 Team
Published: November 2021

In this work we present the extensive validation of a refined version of the integrated model based on engineering parameters (IMEP) introduced in reference (Luda et al 2020 Nucl. Fusion
60 036023). The modeling workflow is now fully automated, computationally faster thanks to the reduced radial resolution of the TGLF calculation, and it includes the modeling of the toroidal rotation, which was still taken from experimental measurements in our previous work. The updated model maintains the same accuracy as its previous version when tested on the cases presented in the initial publication. The confined plasma, from the magnetic axis to the separatrix, is simulated without using any experimental information from profiles measurements, and the inputs of IMEP are the same engineering parameters used when programming a plasma discharge. The model validation database consists of 50 ASDEX Upgrade (AUG) stationary (over a few energy confinement time) H-mode phases, which largely cover the entire AUG operational domain. The prediction of IMEP is compared with experimental measurements and with scaling laws, such as the IPB98(y,2), the ITPA20-IL, and AUG specific regressions. This modeling framework has proven to be very accurate over the entire set of 50 cases, with a significantly lower mean relative error with respect to each of the scaling laws considered, accurately reproducing the change in pedestal and core confinement caused by a change in plasma current, heating power, fueling rate, triangularity, magnetic field, NBI voltage (i.e. the effect of a change in the core particle source), and heating mix (e.g. correctly predicting the effect on confinement caused by a change in T
e/T
i). Plasma confinement is correctly described by IMEP also for two particular operating regimes, such as the ITER baseline scenario, and the QCE regime (quasi continuous exhaust, also referred as type-II and small ELMs). This work clearly demonstrates the power of this approach in pulling out physics mechanisms to interpret subtle interdependencies and that a 1D integrated model can reproduce experimental results over very large parameter variations with a higher accuracy than any statistical regression. This approach has therefore the potential to improve the prediction of the fusion performance in future tokamak reactors.
Pandemic spread in communities via random graphs
Authors: Minzer Dor , Oz Yaron , Safra Muli , Wainstain Lior
Published: November 2021

Working in the multi-type Galton–Watson branching-process framework we analyse the spread of a pandemic via a general multi-type random contact graph. Our model consists of several communities, and takes, as input, parameters that outline the contacts between individuals in distinct communities. Given these parameters, we determine whether there will be an outbreak and if yes, we calculate the size of the giant-connected-component of the graph, thereby, determining the fraction of the population of each type that would be infected before it ends. We show that the pandemic spread has a natural evolution direction given by the Perron–Frobenius eigenvector of a matrix whose entries encode the average number of individuals of one type expected to be infected by an individual of another type. The corresponding eigenvalue is the basic reproduction number of the pandemic. We perform numerical simulations that compare homogeneous and heterogeneous spread graphs and quantify the difference between them. We elaborate on the difference between herd immunity and the end of the pandemic and the effect of countermeasures on the fraction of infected population.
First bioimpedance assessment for detecting effects caused by environmental stimuli on Grapevine ( Vitis vinifera L.): preliminary results
Authors: Barboni Leonardo , Fourment Mercedes , Tachini Ramiro , Mart´ınez Mauro , Quero Gaston , Dell’Osa Antonio H.
Published: November 2021

Plants comprise biological tissues where bioimpedance could be measured. Changes in values of these impedance parameters within tissues are the result of changes in the chemical composition of the sap, cellular depolarization, and ion transport in response to external stimuli such as water availability, diseases, and photosynthesis activity, among others. Therefore, the environmental effects on the plant change its morphology and physiology would be related to bioimpedance. In this way, bioimpedance could become a novel and powerful technique used to analyze, in-situ and in real-time, the physiologic activity and status. In this study, we assess the Evaluation Board AD5933EBZ as a bioimpedance low-cost measurement device to perform observations of module and phase of the bioimpedance, aimed to correlate them with the effects of environmental stimuli such as irrigation, CO2 concentration, sun exposure and temperature level in the grapevine.
Development of electronic modules for their integration with impedimetric transducers applied to sarcosine detection
Authors: Perez-Nava A , Vallejo-Becerra V , Fernández-Puig S , Oza G , Herrera-Celis J
Published: November 2021

The development of fast, simple, sensitive, and minimally invasive biosensors for detecting diseases, conventionally need specialized, expensive, and highly invasive instrumentation. Furthermore, such biosensors pertinently also, need the development of optoelectronic modules that are capable of implementing specific detection techniques while interacting with the user through a friendly interface. This work highlights the development of a system whose hardware and software contributes to the detection of analytes by impedimetric sensors, especially emphasizing on the detection of sarcosine, a natural amino acid associated with prostate cancer (PCa). Dummy circuits coupled with impedimetric transducers were used to perform precise measurements using a sinusoidal signal of 20 mV in the range from 0.1 Hz to 1 MHz.
Wireless connection of bioimpedance measurement circuits based-on AD5933: a state of the art
Authors: Apátiga D , Suárez K , Ramírez-Barrios M , Dell’Osa A H
Published: November 2021

This contribution describes the state of the art in bioimpedance measurements through development boards to build portable devices that perform in-situ measurements and potential technological opportunities to separate the AD5933 integrated circuit from a PC. The presented research is based on prototypes developed with the aim of achieving portability with the AD5933 integrated circuit and it includes different wireless connection methods and a varied software design for the acquisition, visualization and storage of data obtained from biological systems. As a result, this work describes twenty articles that perform wireless connectivity using different microprocessors for different applications. These references seek to explore technological trends, deficiencies, and opportunities for future development projects in telemedicine.
Estimation of Cole Parameters in ex-vivo tissues as a function of degradation time
Authors: López N , García D , González-Correa C A , González-Díaz C A
Published: November 2021

Bioimpedance spectroscopy has been used to evaluate and characterize the integrity of different tissues and organs, as well as to detect tissue structural alterations. The tissue electrical model alterations as an influence of the anisotropy of the tissue structure and its intrinsic metabolism on the degradation dynamic have not been completely understood. In this work, the dynamic of Cole parameters was estimated as a function of degradation time in ex vivo skeletal muscle, skin, and white adipose tissues. The results indicate a non-linear behavior function of the Cole parameters through degradation progress in the three evaluated tissues, and such non-linearities might be associated with different capacities of adaptation to anaerobic metabolism, energy production, and water content under stress conditions.
Software for Gene-Biosensor based on PCR and Electrical Bioimpedance
Authors: Castillo-Salazar I A , Ames-Lastra G , Sacristán-Rock E , Hernández-Nava A , González-Díaz C A
Published: November 2021

Gene detection by the use of bioimpedance measurements is an emerging technical proposal from the last two decades. Our recent studies have shown the feasibility to use multifrequency bioimpedance to detect specific label-free Deoxyribonucleic Acids (DNA) sequence in the final product of Polymerase Chain Reaction (PCR). We have developed a gene-biosensor integrated by a thermocycler block for final point PCR process and a relative bioimpedance meter at every PCR cycle in the sample. The system demands a dynamic software for all gene-biosensor modules control. This work reports a control program design for a gene-biosensor based on PCR product and bioimpedance measurements, the general structural philosophy, operating routines and subroutines as well as its interaction with the hardware in every module are described. The program was designed on the basis of Python language version 3.8.3 with the support of the Visual Studio Code as Integrated Development Environment (IDE), and using Windows 10 as the operating system. Results indicate the control program allows a suitable governing of the bioimpedance meter and PCR thermocycler block, both as a well-integrated system. Bioimpedance and temperature measurements are in agreement with the control operating structural design. Additional amendments regarding an on-line monitoring system are warranted.
Bioimpedance plethysmography with capacitive electrodes and sole force sensors: comparative trial
Authors: Morales Isabel , González-Landaeta Rafael , Simini Franco
Published: November 2021

Foot impedance plethysmography was implemented using two types of electrodes (dry and capacitive) and sole force sensors. The latter are commonly used for assessing diabetic foot ulcers (DFU). For impedance plethysmography, a tetrapolar configuration has been used with three different plantar setups: four skin contact electrodes, four capacitive contact electrodes and two Force Sensing Resistors (FSRs). In this work, FSRs have been considered as possible capacitive electrodes because the top substrate contains interdigitating conductive electrodes and a semiconductive polymer. All the measurements have been performed using a 1 mA/10 kHz excitation current and have been tried under the feet of a standing person to detect impedance plethysmography signals. Contact electrodes allow a good cardiac pulse signal while capacitive contact through the socks features mains interferences. Force sensing resistors with their force-dependent resistance in parallel to the capacitive coupling, were not able to detect cardiac pulse. But promising results can be anticipated from these findings provided higher frequencies are used and larger sensor areas to help detect altered skin states in diabetic foot.
Correlation between the Concentration of DNA and Electrical Bioimpedance
Authors: Hernández Angélica , Ames Gerardo , Sánchez Virginia , Gómez Modesto , Sánchez Jennifer , Pérez Nadia M , Castillo Itsi A , González César A
Published: November 2021

Biosensors have recently been used for the identification and genetic characterization of diseases such asSalmonella, human papilloma, and breast cancer. The aim of this study was to examine the relationship between different concentrations of Deoxyribonucleic Acid (DNA) and the corresponding values of magnitude and phase of Electrical Bioimpedance (EBI). Functions that characterize the correlation of DNA with these two parameters were derived from linear regression by means of the least squares method. According to the results, it is feasible to determine the concentration of DNA from EBI measurements (at a specific frequency) of magnitude and phase, taking into account the corresponding linear functions. The present findings indicate the feasibility of using EBI measurements of magnitude and phase as a biosensor for the detection of genes associated with genetic and infectious diseases.
Simulation of impact load modulation device based on drill string vibration
Authors: Lu Xiaopeng , Liao Hualin , Wang Huajian , Niu Wenlong , Liu Jiansheng
Published: November 2021

The longitudinal vibration of the bottom drill string is violent and the law is complex during the deep well drilling. The vibration of the drill string brings many adverse effects on the drilling pipe fracture and bit trampoling. Generally speaking, the effective way to control the vibration of drill string is to install damping device in bottom hole. The research group proposes a device that uses the longitudinal vibration energy of the deep well drill string to modulate the impact dynamic load, which converts the vibration energy of the downhole drill string that is not conducive to drilling into the mechanical impact energy that improves the rock breaking capacity of the bit. The impact load modulation device can use the drill string to apply the “mechanical WOB” and the differential pressure between the upper and lower piston to produce the “hydraulic WOB”, The simulation results show that the adjustable range of output load is 2 ~ 7T, and the change of each time is about 2T. The modulation law of impact load under the influence of longitudinal vibration of drill string and different parameters is analyzed. Through ground experiment and simulation, the damping performance and speed-up effect of the modulation device are compared and analyzed, and the impact load output characteristics of the device are analyzed, which provides a thinking for the design of damping and pressurization tools.
Steering Wheel AGV Path Tracking Control Based on Improved Pure Pursuit Model
Authors: Wu Yiyang , Xie Zhijiang , Lu Ye
Published: November 2021

Aiming at the path tracking problem of the AGV transfer platform of an Optical module installing and calibrating system, this paper designs a pure pursuit control strategy in which the preview distance changes adaptively according to the current speed of AGV and the curvature of the reference path. Firstly, AGV kinematics model and pure pursuit model are established according to the geometric relationship. Then fitness function is established with tracking deviation and steering stability, and Particle swarm optimization (PSO) algorithm is used to optimize the preview distance of pure pursuit model of AGV under various working conditions. During the tracking process, AGV selects the optimal preview distance according to the curvature of the reference path and the current speed. The simulation experiment results show that the improved pure pursuit control strategy containing curvature information of reference path can improve the adaptability of AGV when it is tracking complex path, guaranteeing tracking accuracy and steering stability.
Coordination of synchronous compensators and converters to improve the commutation failure recovery performance in HVDC systems
Authors: Wu Kuayu , Zhang Jiancheng , Zhou Yongzhi , Zhu Yuhong
Published: November 2021

A novel control strategy of synchronous compensators and converters is proposed to increase the ability of line commutated converter (LCC) based HVDC systems to successfully recover from commutation failures (CFs). The dynamic var support is one of the most important factors, which impact the commutation process. Many synchronous compensators have been implemented to enhance the transient voltage stability for improving the CF recovery performance. However, the traditional automatic voltage regulator (AVR) of synchronous compensator may not be suitable for the commutation voltage support, because the transient var demand of converters during the CF recovery is neglected. In our work, the voltage control will be adaptively adjusted, depending on the state of converters. Case studies based on simulations in PSCAD/EMTDC show that the proposed strategy can improve the performance of fault recovery from CF.
Research on relative orientation method of oblique aerial photography based on basic matrix
Authors: Wang Zehong , Xiao Long
Published: November 2021

After the oblique aerial photography technology is used to collect the stereo image, it is necessary to use the relative orientation method to check the image parameters. After the rectification process is completed, the 3D software is used to draw the 3D model to meet the subsequent application requirements. The author of this paper analyzes the difficulty of the matching and aerial photography, including affine transformation cannot successful transformation, influence there covered phenomenon and characteristic finishing is difficult, the combination of fundamental matrix tilt aerial photography as a method of relative orientation, through the study of oblique aerial photography based matrix as precision control points, its aim is to continuously optimize tilt aerial photography as the content, improve the use value of collation results.
Research on Digital Twin Virtual Model of UHV Core Power Equipment
Authors: Zhang Shiling
Published: November 2021

In this paper, voltage equalization, corona prevention and noise reduction are studied by using finite element calculation method and multi-objective optimization algorithm for UHV substation, series compensation circuit, transmission line, DC valve hall and outdoor field. The calculation model of multi parameter and multi-objective optimization design is established, the optimal configuration parameters of voltage equalizing structure are obtained, the electric field distribution uniformity and structure rationalization are realized, the corona discharge is effectively restrained, the key technology of voltage equalizing and anti corona is solved, the cost is reduced, the efficiency is improved, and a simulation calculation and optimization design platform with independent intellectual property rights is formed. The research results have been successfully applied to UHV projects in China.
DOA Estimation of a Space-limited MIMO Radar with High Degree of Freedom
Authors: Yue Shijie , Hu Guoping , Zhan Chenghong , Zhang Yule , Zhu Mingming
Published: November 2021

Aiming at the problem of the small aperture of the traditional MIMO radar with virtual degrees of freedom, this paper designs a high degree of freedom space-limited MIMO radar. Both the transmitting and receiving elements of this radar adopt a sparse array structure. Array composition, the receiving array element is composed of a single array element and a uniform linear array. The number of virtual array elements can be realized by using array elements. Compared with the traditional sparse array MIMO radar with the same number of elements, the designed space-limited sparse array MIMO radar has a larger aperture. Experimental simulations verify the superiority of the space-limited MIMO radar angle estimation.
A Research on Modulation in Digital Communication System
Authors: Niu Xinyu , Wu Jingdong , Zhang Linen
Published: November 2021

With the development of network and communication technology in modern society, WiFi technology has become an indispensable part of people’s lives. WiFi shows its future application prospects with its wireless portability and multi-user access. This paper briefly introduces the meaning and development of WiFi technology and predicts its future development trend. The communication modulation technology QPSK, 16QAM in WiFi is described in detail, and its characteristics are compared by systemview and MATLAB software. Finally, we summarize the common techniques in WiFi.
Research on Simulation and Test of Spatial Isolation Based on Geographic Information
Authors: Wang Yuan , Tan Wei , Kong Rong , Ren Zhaorui
Published: November 2021

In the process of site selection for the deployment of distributed systems, in order to solve the problem of inaccurate spatial isolation simulation results caused by the large influence of complex geographic information such as terrain and weather on the propagation of radio waves, and to solve the problem of inefficient and inefficient spatial isolation testing. This paper proposes to select suitable propagation models for different geographical information in different regions, clarifies the simulation calculation method, and proposes a test method to accurately determine the direction of the transceiver antenna for the minimum spatial isolation. By comparing and analyzing the simulation calculation results and test verification results, correction parameters such as simulation system error, atmospheric absorption loss, and geological absorption loss are proposed. This article analyzes and studies the correction value of radio wave transmission loss of S-band electromagnetic signal under different geographic information conditions such as snowfall and iron ore through an example. It can provide reference values for some of the influencing factors of electromagnetic signal propagation loss under geographic information conditions, and it can improve the accuracy of the simulation calculation results of the spatial isolation under the conditions of geographic information.
Design of transceiver based on functional programming
Authors: Zhao Zhuomao , Yang Yujie , Long Xue , Cui Hongwei
Published: November 2021

This paper discusses the setting of transceiver based on functional programming, and decouples the differences between communication protocol and network transmission protocol from the specific business implementation. In the actual application, the service implementation is set up. When the communication protocol changes, the function can be realized only by modifying the communication protocol, which improves the readability of the program and reduces its maintenance overhead
An Improved PMF-FFT Algorithm Based on Hamming Window
Authors: Cheng Lingfeng , Ni Shuyan , Chen Shimiao
Published: November 2021

When the rocket uses low-orbit satellite space-based measurement and control, due to the relatively large Doppler shift in relative motion, a spread spectrum system is needed to improve anti-interference; the spread spectrum signal under high dynamic conditions often uses partial matched filtering based on FFT (PMF-FFT) algorithm, but due to the introduction of FFT, this algorithm has serious scallop loss, which affects the system’s capture performance. Through the improved method of adding a Hamming window to the system, theoretical analysis and simulation show that it effectively suppresses scallops. Loss has a certain meaning for the acquisition of spread spectrum signals.
A time-division correction method for adaptive optics system
Authors: Yuan Guangfu , Zhao Lirong , Wu Peijian , Wang Weijie
Published: November 2021

An adaptive optics system can measure and compensate the wavefront distortion caused by dynamic disturbance in real time. It is usually used for astronomical observation and other occasions. According to the current technology, it is only suitable for small field of view optical system or point target, but not for ground extended target detection. In order to solve this problem, a correction method is proposed: firstly, the sub aperture image of wavefront sensor is divided into several sub regions, each sub region corresponds to a certain light direction or field angle range; secondly, calculate the offset of the image feature points in each sub region, and an image with good correction effect in a field of view in this direction is obtained; the last step is to measure each sub region one by one and combine these images into a full frame image. Through comparison, it is found that the method proposed in this paper is essentially to divide the extended target into multiple point light sources for correction.
Analysis of eddy current loss in magnetic coupling based on three-dimensional finite element calculation
Authors: Wang Xiaoyue , Cai Liang , Mao Yanqin , Guo Wanjun
Published: November 2021

Considering the end effect, the three-dimensional finite element calculation model of the magnetic coupling is established. The three-dimensional distribution nephogram of the induced current and eddy current loss on the isolation cover is obtained, and the distribution trends of the two are consistent. The influence of size, material, and operating condition of magnetic coupling on eddy current loss is studied. The results show that the selection of isolation material with high resistivity and the reduction of isolation thickness are helpful to reduce the eddy current loss. The higher the rotating speed of the magnetic coupling, the greater the eddy current loss. At the same speed, the greater the load, the greater the magnetic declination, the smaller the eddy current loss. The research results can provide a reference for reducing energy loss and cooling structure design of magnetic coupling.
Fluid-Structure Interaction Approach to Single Particle in a Square Microchannel
Authors: Li Xiang , Lin Ying
Published: November 2021

Inertial microfluidic technique has been widely applied on particle/cell manipulation and detection. To understand the physical principle of this technique more detailed, the interaction of fluid and particle was studied through the Fluid-Structure Interaction (FSI) method. The equilibrium positions of finite-size particles with different diameters were simulated at moderate Reynolds numbers. The flow structure around two typical particles was analysed. The vortex in the front of the particle retards particle’s translation leading to the lag velocity increasing. Finally, the rotation velocity and the rotational-induced force analysed quantitatively to demonstrate that particle’s self-rotation significantly promotes its inertial migration.
Optimization and Application of D850 Dredge Pump Blades under Medium Coarse Sand Condition of Cutter Suction Dredger
Authors: Zhuang Haifei , Liu Mingming , Wu Yongding
Published: November 2021

Regarding wear issues of a dredge pump’s impeller as a cutter suction dredger transports medium coarse sand slurry, blades of the D850 dredge pump are modified and optimized, which extends the distance from the blade inlet root to the impeller suction and avoids damages of the impeller suction anti-wear ring. Analyses via computational fluid dynamics (CFD) simulation show that the head and the efficiency after blade modification have little changes compared with before optimization in the construction flow range of 10000-12000 m3/h under coarse sand condition. While it improves the flow field of impeller’s channels, decreases the vortex at the inlet root of the blades, ensures more uniform distribution of the solid particles. Meanwhile, this is beneficial to reductions of the channels’ wears. Applications from constructions show some improvements in the wears of the blade root. Through the construction data comparison, after replacing the modified impeller, dredging productivity will be increased by 15.1% and the fuel consumption per 10000 m3 will be then reduced by 11.5%.
Singularly Perturbed Solutions for a Class of Thermoelastic Weakly Coupled Problems
Authors: Bao Liping , Shuai Xin , Wu Liqun
Published: November 2021

Based on the basic equation of Green Lindsay (G-L) theory, the thermoelastic weak coupling problem under the basic equation is discussed, that is, two thermal relaxation parameters are added to the constitutive equation, the influence of the coupling term on the temperature field and elastic field is considered, and the asymptotic solution of the governing equation is constructed. Firstly, in order to obtain the asymptotic solution, the singularly perturbed expansion method is used.Then,combined with the corresponding boundary conditions, the partial differential equation method is used to solve the external solution and the boundary layer correction term. Secondly, in the case of weak coupling, the uniformly efficient estimation of the remainder of the asymptotic solution is obtained by using Gronwall inequality, so as to obtain the uniformly efficient of the formal asymptotic solution. Finally, the first term of the asymptotic solution is numerically analyzed by using the singularly perturbed numerical method. The present work will be conducive to the analysis of thermoelastic processes and numerical simulation of different materials in the case of weak coupling.
Review of Calibration and Improvement Methods of Light- Scattering Airborne Particle Concentration
Authors: Gao Z L , Cheng Q D , Zeng G L , Wen Y , Li G F , Chen J , Dong Y B , Ji Q Z
Published: November 2021

Clean environment and its internal airborne particle concentration have been paid more and more attention, the demand for use and measurement of light-scattering airborne particle counter, as the main instrument for measuring airborne particle concentration, has increased synchronously. This paper untangles the worldwide standards and specifications for calibration of light-scattering airborne particle counter, analyses the shortcomings of traditional comparative calibration method, introduces the research progress of non-traditional calibration method based on statistical analysis of membrane and scanning electron microscope, then based on the theory of discrete phase model and gas-solid fluid dynamics, puts forward two improved calibration methods to obtain more reliable "true value" of the number of the standard particles passing through the calibrated OPC, to provide an innovative idea for improving the measurement accuracy of airborne particle concentration worldwide.
Study on Micro Recoil Mechanism of the Weapon with a Nozzle and Two Chambers Separated by a Partition
Authors: Ma Longxu , Qiu Ming , Song Jie , Si Peng , Liao Zhenqiang
Published: November 2021

In order to improve the recoil reduction ability of the weapon without reducing the projectile velocity, the weapon with a nozzle and two chambers separated by a partition is proposed. Taking the 35 mm caliber grenade launcher as the research object, the physical model of its launching process is proposed, and the one-dimensional two-phase flow interior ballistic model is established. MacCormack difference scheme is used to calculate the coupling of multiple physical fields formed by front and rear chambers and nozzles. Compared with the calculation results obtained by using the classical interior ballistic model, the correctness of the two-phase flow interior ballistic model is verified. The effects of the charge amount in the rear chamber and the size of the air guide hole in the barrel on the internal ballistic performance of the weapon with a nozzle and two chambers separated by a partition. The calculation results show that compared with conventional weapons, the recoil impulse can be reduced with maintaining muzzle velocity, and the recoil reduction efficiency can reach 72.27%, which is of great significance for improving weapon performance.
Numerical Investigation on Radiation Effect in Transpiration Cooling
Authors: Qian Kang , Liu Taolue , He Fei , Wang Meng , Tang Longsheng , Zhou Jianxing
Published: November 2021

This paper proposed a numerical strategy which could achieve the coupled modeling and solving of transpiration cooling with external high-temperature gas flow and especially take the radiation effect into account. Based on the numerical strategy, the heat and mass transfer characteristics of the transpiration cooling in a high-temperature gas channel were studied, and the radiation effect and corresponding influence factors were analyzed. The results indicated that the radiative heat flux takes an important role in the heat transfer between the transpiration cooling and external high-temperature gas flow which may reach 40% under the operating condition considered in this work, and the radiation absorption from the coolant is more obvious near the downstream wall. As the wall emissivity increases, the radiation heat transfer in the downstream area of the porous wall is enhanced significantly and thereby the wall temperature there increases, as the result, the uniformity of the temperature distribution on the whole porous wall is improved to some extent.
Simulation Study on the Influence of Injector Coupling Leakage on Fuel Injection
Authors: Zhang Ziwei
Published: November 2021

In order to study the effect of fuel leakage of an ultra-high pressure common rail injector control valve coupling on fuel injection performance, a simulation model was established by AMESim and the accuracy was verified by fuel injection test data. The leakage law of couples with different clearances was analyzed by using numerical simulation method and then the influence of control valve coupling on fuel injection performance was analyzed. The results demonstrate that the increase of the matching clearance of the slide valve coupling makes the start time of needle valve advanced and delay its end time. The injection rate and injection duration increase with the increase of the matching clearance of slide valve coupling. The increase of the matching clearance of the control plunger coupling keeps the start time of the needle valve unchanged at first, and then delay slightly, while the end time remains unchanged at first, and then show the trend of advance. The injection rate and injection duration decrease with the increase of the matching clearance of plunger coupling.
Investigation of Huge Wave in Gas-Liquid Two-Phase Churn Flow
Authors: Zhang S , Shao Q Q , Hu B , Wang K
Published: November 2021

Churn flow frequently occurs in power plants, chemical engineering, petroleum, and other industrial applications. Due to its chaotic nature, churn flow has a significant influence on safety and management control. As one of the essential characteristics of churn flow, depth knowledge of the huge wave is crucial for a better understanding churn flow. However, relevant studies on these issues are still in shortage because it is difficult to capture its behaviours experimentally. In this study, we employed the high-speed camera to capture the evolution and properties of huge waves under churn flow conditions in a vertical pipe. The inner diameter of the pipe is 19 mm. Based on the observation, the flooding of the falling film in churn flow is demonstrated to be the slug/churn transition mechanism. Additionally, the liquid distribution in the cross-section of the tube is provided and discussed in detail. Compared with the existing experiment data, we carefully analyze the properties of huge waves, such as frequency and amplitude.
Research on the Effect of Key Technological Parameters on Molten Pool during Selective Laser Melting Processing
Authors: Wang Wentong , Tang Linfeng , Chen Congyan , Li Yu , Zhou Tao
Published: November 2021

Selective laser melting (SLM), as an emerging technology in additive manufacturing, often has various defects in the forming process. To ensure the consistency and stability of the parts forming quality, the effects of two typical technological parameters, laser power and scanning speed, on the temperature of molten pool are investigated in this paper. Firstly, the temperature field of Ti-6Al-4V is simulated theoretically via ANSYS software, and the effects of two typical technological parameters on the temperature field are studied. Then, in the experiment, using the designed radiation monitoring device and Ti-6Al-4V powder as forming material, the influence of these two typical factors on the state of molten pool is studied. The simulation and experimental results show that the temperature of molten pool shows positive correlation with the laser power and negative correlation with the scanning speed. This will provide a certain reference value for upgrading and optimizing SLM equipment.
Numerical Simulation of Internal Flow Field of Self-Designed Centrifugal Pump
Authors: Wang Xin , Zhang Jun , Li Zongshun
Published: November 2021

The two self-designed of centrifugal pump with small vane and centrifugal pump without small vane were simulated numerically to select a centrifugal pump with higher efficiency. The internal flow characteristics of the centrifugal pump was simulated by using Reynolds time-averaged N-S equation and RNG turbulence model to obtain pressure and velocity distribution and the cavitation characteristics were simulated by using SST turbulence model and Schnerr-Sauer cavitation model to obtain the gas volume fraction distribution. The results show that at the same flow rate, the change of velocity in the pump cavity of centrifugal pump with vane is smoother and the gas volume is less, but the back-flow is aggravated near the small vane, especially when interacting with the tongue, and a large amount of gas is generated at the suction surface of the small vane. In addition, the efficiency of centrifugal pump without vane is higher than that of centrifugal pump with vane, which provides a basis for the structural optimization of centrifugal pump.
Preparation and Application of CQDs/Ni(OH)20.75H2O as Electrodes in Supercapacitors
Authors: Zhou Yunlong , Fu Hanxiu , Peng Junwen , Chen Weize , Cen Kunfeng , Lv Jingru , Cao Xiaofen
Published: November 2021

In this paper, a hydrothermal synthesis method for preparation Carbon Quantum Dots (CQDs)/Ni(OH)20.75H2O composite electrode material, and loaded on Nickel Foam(NF) by rolling method. The crystal phase, structure, morphology and the reaction process were characterized by X-ray diffractometer (XRD) and scanning electron microscopy (SEM). The electrochemical properties of the composite were measured by cyclic voltammetry impedance spectroscopy and couple method charge-discharge techniques. The results showed that the composites material was evenly adhered to nickel foam. When the current density is 1 A g−1, the specific capacity of CQDs/Ni (OH) 20.75H2O composite can reach 2115.4 Fg−1, which is close to 5 times of Ni (OH) 20.75 H2O electrode material.