bluuebunny/crossref_metadata_2025 huggingface dataset:
Research of Multi-objective Component Assignment Problem for Lin/con/k/n System Considering Cost
Authors: Rashid Muhammad , Cao Huiying , Ma Chenyang , Rehman Mudassar , Cai Zhiqiang
Published: February 2021

Component assignment problem (CAP) is widely used in engineering systems, which is investigated for enhancing the system performance by assigning switchable components to several positions. However, the traditional CAP does not consider the cost factor and has limitations for improving the system reliability. Therefore, this paper focus on a multi-objective CAP for Lin/con/k/n system to find the cost-efficient maintenance scheme. Firstly, a multi-objective mathematical optimization model is developed with the aim of maximizing the system reliability and minimizing maintenance cost, which has been proved to be a Non-deterministic polynomial hard problem and should be computed by heuristics. Secondly, a comprehensive maintenance method is adopted to improve the system reliability, which integrates improving the system reliability with changing the permutation of components. To evaluate the contribution of the component reliability on both system reliability and maintenance cost, the multi-objective Birnbaum importance (MOBI) is derived. Finally, MOBI is introduced into the non-dominated sorting genetic algorithm-II (NSGA-II) to solve the optimization model. The numerical experiments for several Lin/con/k/n Systems show that MOBI is available to solve CAP considering cost, and MOBI-based-NSGA-II algorithm is more efficient to obtain higher system reliability with lower maintenance cost.
Fatigue Analysis and Structural Optimization Design of the Slot of Knotted Frame of the Square Baler
Authors: Ma Wei , Cen Hai- tang , Guo Wang , Li Ling , Na Ri-su
Published: February 2021

The frame is a key part to ensure the reliability and life of the knotting device of the square bale baler, and it is also the difficulty of localizing the knotting device. The inner wall of the frame slot of the frame is at a right angle structure, and the stress concentration is obvious. Under the impact load, the stopper will cause premature shear failure, delay the timing of forage bale, increase maintenance costs, and reduce the operating efficiency of the baler. This paper analyzes the failure characteristics of the D-type knotter frame slot, uses ANSYS-nCode joint method to simulate the fatigue life of the knotter frame slot, and uses the response surface method to optimize the design of a U-shaped slot. The simulation results show that when the radius of the U-shaped slot is 2mm and the gap between the bottom of the slot and the first rope clearing piece is 1mm, the fatigue life of the U-shaped slot increases. This research is of reference value to improve the fatigue performance of the knotter frame and enhance the durability of the knotter.
Crack orientation detection in plate-like structures via Lamb wave specular reflection analysis
Authors: Li Xu , Zhang Nan , Zhai Mengsheng
Published: February 2021

The determination of crack orientation plays an important role in the non-destructive evaluation (NDE) of plate-like structures. In this paper, the interaction between Lamb waves and cracks is investigated using the time domain spectral element method (SEM) as the simulation tool. On that basis, we analyse the geometric principle of specular reflections and propose an efficient crack angle detection algorithm. During the process, four sensors take turns to excite the Lamb wave which would result in twelve crack reflection signals. Using the corresponding actuator as the centre and the reflection length as the radius, we can obtain twelve reflection circles in total. When these reflections are specular, the mirror points of the actuators with respect to the crack line are exactly the intersection points of the circles. Thus, we can obtain the crack angle by this geometric relation. Validations on different cracks are made and the result of the algorithm shows a good agreement with the real value.
Pipeline volumetric defect assessment method based on multi risk factors and in-line inspection data
Authors: Ling J T , Dong S H , Zhang H
Published: February 2021

Volumetric defects in pipeline is one of the main factors causing pipeline leakage accidents. Once an accident occurs, it will cause huge economic and environmental loss. At present, the assessment of pipeline volumetric defects in existing standards is only calculate the residual strength of pipeline by defect size (length, width, depth), without considering the influence of other external risk factors. Therefore, defect-related risk factors were introduced when calculating the residual strength of defects using in-line inspection data. Due to the massive data resources produced during the construction and the operation period, a risk factor correlation analysis model for extracting the risk factors related to the pipeline safety was established. The weight of each factor is obtained by using analytic hierarchy process algorithm, and a new defect risk index was put forward. Therefore, the volumetric defect assessment method based on multiple risk factors of defects and in-line inspection data is proposed. The result of on-site examples shows that the defect assessment method proposed in this paper can reflect the true safety status of the defects, it can also provide support for scientific and reasonable pipeline maintenance decision.
Reliability evaluation method of LED lighting matrix considering degradation and catastrophic failure
Authors: Gu Changchao , Li Lexiao , Ye Nanxin , Chang Hao
Published: February 2021

Aiming at the current situation of degradation and catastrophic failure of weaponry, a reliability modelling method considering performance degradation (lumen degradation) and catastrophic failure (nonluminous) is proposed with LED lighting matrix as the research object. First, for the degradation of lumen, the failure mechanism analysis is carried out, the thermal resistance model of lighting matrix and radiator is established, and the overall model of the degradation of the LED lighting matrix is realized. For the catastrophic failure, based on the uncertainty of the logic relationship of catastrophic failure of lighting matrix and the polymorphism of individual fault events, the method of combining fault tree and Bayesian network is used to realize the analysis of failure evolution and reliability modelling. Finally, the validity of the proposed method is verified with a case study.
Fault diagnosis of rolling bearing based on empirical mode decomposition and convolutional recurrent neural network
Authors: Huang Mulin , Huang Tingting , Zhao Yuepu , Dai Wei
Published: February 2021

Bearing is more important in mechanical parts. Many failures of rotating machinery are caused by bearing failure. It is very important to diagnose the rolling bearing fault and help the mechanical products to find out the failure of parts in operation. It can avoid danger and improve efficiency. To research the problem of rolling bearing fault diagnosis under different loads, a method using vibration signals based on empirical mode decomposition (EMD) and convolutional recurrent neural network (CRNN) is proposed. First, the EMD is used to deal with the vibration signal for noise reduction. Then, CRNN is built as the rolling bearing fault diagnosis classifier using the envelope of EMD processing. The Case Western Reserve University data sets are used to validate the method. The result shows that the method fits well.
Improved response surface method based on triple weighted regression
Authors: Wu Jie , Zhang Jianguo , You Lingfei , Ye Nan
Published: February 2021

The response surface method (RSM) is frequently used to reduce the computational burden of structural reliability analysis. In this paper, an improved RSM is proposed. The response surface is fitted by the triple weighted regression technique, which integrates weighting systems to assign weight factors to each sampling point including (1) the absolute value of the limit state function (LSF), (2) the value of the joint probability density function and (3) the distance from the design point. Numerical examples are presented to demonstrate that the proposed method gives more accurate results than RSM for both probability of failure (PoF) and LSF evaluations.
Structural reliability analysis with temporal and spatial variations based on polynomial chaos expansion
Authors: Nan Hang , Li Hong Shuang , Xue Cai Jun
Published: February 2021

Performance of engineering structures varies with time and space due to the uncertainties in time and space domain. This paper presents a polynomial chaos expansion (PCE) based method to evaluate the reliability problem with temporal and spatial variations. The sequential quadratic programming (SQP) is employed to obtain the samples of spatial response extreme value at discrete time instants, and then the surrogate model of spatial response extreme value can be constructed by PCE based on those samples. Therefore, the structural response hypersurface in time and space domain is transformed into a trajectory of spatial response extreme value in time domain and the reliability analysis can be achieved by Monte Carlo simulation (MCS). Three examples are used to demonstrate the performance of the presented method in accuracy and efficiency.
Application of BP Neural Network and Convolutional Neural Network (CNN) in Bearing Fault Diagnosis
Authors: Deng Hai , Zhang Wan-xuan , Liang Zheng-feng
Published: February 2021

The convolutional neural network (CNN) identification method and the BP neural network identification method were used to diagnose the bearing fault respectively. When using the CNN diagnostic method, first perform continuous wavelet transform (CWT) on the vibration signal of the rolling bearing to obtain a time-frequency map, and then compress the time-frequency map to an appropriate size; Then, the compressed time-frequency map is used as a feature map to input into the CNN classifier model established; finally, an experimental study is carried out based on the artificial bearing fault data set of Western Reserve University. The results show that the average accuracy rate of this method is greater than 99%.In the BP fault diagnosis method, based on the data set, nine parameters of average value, maximum value, minimum value, peak-to-peak value, root mean square value, standard deviation, variance, skewness and kurtosis are established as training input vectors. Using BP neural network with 10 hidden layer nodes for fault identification, the results show that the average accuracy of identification is 93.7839%. The comparative analysis of the two methods shows that the BP identification method has higher training efficiency and takes less time; the CNN identification method has higher recognition accuracy, but the training takes more time.
Influential Parameter Analyses for Sinking Velocity with Measured Data
Authors: Xue X F , Feng Y W , Du Q Y , Lu C
Published: February 2021

To study the effect of operational parameters on the sinking velocity of the landing gear of carrier-based aircraft, the influential analyses of various related parameters were performed based on the measured data of F/A-18. The probabilistic statistical characteristics of the sinking velocity were firstly investigated. And then correlation coefficient method and Levenberg-Marquardt (LM) algorithm were applied to finish influential parameter analyses. The analysis results show that the important influential parameters are aircraft glide angle, deck pitch angle, approaching velocity and engaging velocity; the mathematical model of sinking velocity is established by LM algorithm, and the determination coefficient is calculated via the variance analysis, which reveals that the proposed regression model is good. Compared with the measured data, the average errors for the predicted values of the established model of sinking velocity are less than 5%, which validates the effectiveness and feasibility of the method in engineering practice. The present efforts provide a way to study the relationships of the sinking velocity and the related influential parameters. And this work was proved to be a useful method for the study of sinking velocity.
Characterization of surface crack width in plates using Rayleigh wave electromagnetic acoustic transducers
Authors: Ahmad Mubarak , Liu Zenghua , Basit Abdul , Bin Wu , He Cunfu
Published: February 2021

Surface crack in the plate like structures is one of the initial indication for its degradation. This indication could be very critical and requires some serious maintenance because this continuous exposure will lead to a severe damage to the safety and even to environment. To evaluate the structural performance and safety, a regular monitoring of such cracks is needed. A quantitative characterization method is utilized for the estimation of surface groove width instead of depth or length, which is previously done by many researchers, using Rayleigh waves in pitch-catch mode using electromagnetic acoustic transducers (EMATs). The method employs the experimentally determined reflection coefficient and transmission coefficient of Rayleigh waves scattered at a surface groove by a number of varying widths, which are compared to the reference curves, obtained from two-dimensional finite element method (2D-FEM) simulations for the same groove width as used in experiments. A good relation between FEM results and experimental results is found. Two different EMAT couples of different centre frequencies were employed to explore the measurement, and to compare and analyse the quantitative characterization of different groove widths. Both the FEM results and experimental results are compared and verified for the different groove widths. This comparison shows some percentage of error for the groove width ranging from 0.3 mm to 1.8 mm.
Demand analysis of quadcopter based on QFD
Authors: Nan Xiang , Lin Huo , Di Gai , Zhenhao Lv , Yikuan Li
Published: February 2021

The quality and safety of quadcopters have always been the focus of attention in the drone industry. Carrying out safety and functional requirements analysis for it can better meet customer needs, reduce design costs, improve reliability and safety, and provide ideas for product design updates. This article uses the QFD (Quality Function Deployment) method to transform the safety and functional requirements of the quadcopter into product design, and provides guidance and reference opinions for improving product quality and safety. Based on the analytic hierarchy process, the article determines the technical difficulty through the analysis of technical characteristics, and analyzes the functional and safety requirements of the quality house model constructed after the improvement of the four-axis aircraft to provide a basis for the improvement of the quality characteristics of the four-axis aircraft.
Comprehensive safety evaluation of metallurgical crane based on AHP and entropy weight method
Authors: Cheng J M , Zhang W M , Jin H
Published: February 2021

The determination of safety evaluation weight of most engineering equipment mainly depends on the subjective experience of experts, which ignores the objective requirements of indicator status evaluation, is unable to satisfy the needs of the evaluation system with the advances in modern equipment health monitoring technology. Hence, the authors establish a safety evaluation model to form a comprehensive weight using experience factors, based on the objective weighting of the entropy weight method (EWM) and the subjective weighting of the analytic hierarchy process (AHP), to integrate the objective analysis data and subjective prior knowledge. Then, a safety evaluation system with state value as the main consideration was built on the combination of knowledge and fuzzy comprehensive evaluation. Finally, the availability of the proposed evaluation method was verified by the example.
Simulation analysis of outage recovery time of navigation satellite
Authors: Zhao Haitao , Xiong Xiao , Wang Qinghua
Published: February 2021

Outage recovery time is an important factor affecting the availability of navigation satellite. In order to effectively estimate the outage recovery time of satellite on orbit at the design stage, this paper analyses the specific process of outage recovery, and puts forward the modelling and analysis method of outage recovery time according to the characteristics of outage recovery process. In this paper, outage recovery time is divided into fault detection time, fault location time, fault handling time, state recovery time and access system time. By using the correlation analysis method, the equipment that may cause outage can be located quickly. Taking the recovery time corresponding to a certain recovery strategy as the input, the recovery time on the satellite can be obtained by weighting the recovery time and failure rate. Considering the randomness of outage recovery process, state flow graph is used to model and simulate the recovery time. Finally, an example of simulation analysis is given.
Reliability design of aerospace secondary power supply based on fault tree analysis
Authors: Gao Ting , Liu Mi , Qu Hong-Yi , Ji Hong-Juan , Jing Jiang
Published: February 2021

As the satellite power supply and distribution functions and complexity are gradually strengthened, the reliability requirements of the aerospace secondary power supply are getting higher and higher. Based on the basic composition and working principle of aerospace secondary power supply, this paper analyzes the reliability of the fault tree analysis method (FTA), combs the weak link of the product, and proposes design improvement measures for the weak link.
Gear Fault Diagnosis Based on GPU-CNN
Authors: Dong Zhipeng , Meng Shuo , Chi Kuo , Kang Jianshe
Published: February 2021

Gear is widely used in mechanical transmission system, but it is prone to failure, which seriously affects the performance of equipment. In order to realize the diagnosis and classification of gear faults, we used Convolutional Neural Networks (CNN) to extract time-frequency image features of its vibration signal. CNN can extract the characteristics of time-frequency signals from vibration signals and identify gear faults accurately. However, due to the large training data set, CNN training costs too much time. According to the characteristics of Graphics Processing Unit (GPU), Compute Unified Device Architecture (CUDA) can improve the speed of CNN algorithm and reduce the time consumption. Therefore, this paper proposes a method based on GPU-CNN for gear fault diagosis. The experimental results show that the method can effectively shorten the training time and significantly improve the operation efficiency.
Dynamics and reliability analysis of the deployment process of spring folding wing
Authors: Gao Yun , Hu Ming , Zhao Deming , Gao Xingwen , Lin Jiangfeng
Published: February 2021

A “X” type spring folding wing is taken as the research object in this paper, and schematic diagrams of unfolding and locking process are drawn according to its structure and working principle. The theoretical model of kinematics and dynamics which considering the gravity moment is established by simplifying the geometric model of deployment mechanism of the folding wing, so the curve of deployment angle and angular velocity of the outer wing during the deployment process can be obtained. The pulley diameter, preload force and stiffness of the spring-actuated are taken as random variables, and the deployment time and angular velocity are regarded as evaluation indicators. The Monte Carlo method is used to analyse the reliability of deployment process of the folding wing, and the reliability of the deployment process is obtained. The results show that the reliability of the deployment process of the spring folding wing is high.
Research on Civil Aircraft Cabin Service Availability Analysis and Application
Authors: Gao Weiyan , Lu Peng
Published: February 2021

Reliability is one of the important characteristics of civil aircraft, it is an important factor to ensure flight safety and high punctuality, and to obtain good economy. The cabin service availability analysis is a key segment in the overall reliability analysis. This paper focuses on ddetermination principle of functions related to cabin service availability and the judgment of failure effects and other contents, and establishes a civil aircraft cabin service availability analysis method and analysis process.
Research on mission reliability and sensitivity of folding tail mechanism
Authors: Pang Huan , Shi Dongyang , Wang Daocheng
Published: February 2021

Folding tail mechanism is widely used in subsonic and super/high sonic missiles, and its mission reliability is directly related to the success or failure of missile launch. Taking the torsion bar folding tail mechanism as the object, the failure modes and failure influencing factors in the mission process are analyzed systematically. The dynamic model of the folding tail mechanism is established. According to its characteristics, the multi-stage correction method of the dynamic model is proposed and realize the high-precision simulation. Finally, the mission reliability and sensitivity analysis is carried out, and the reliability sensitivity of folding tail mechanism is obtained, which lays the foundation for reliability optimization.
Optimization Of The Measurement Precision Consistency Of Single-Phase Smart Electricity Meters In Full Temperature Range
Authors: Ye Xuerong , Lyu Mingdong , Sun Qisen , Yuan Ruiming , Li Wenwen
Published: February 2021

With the development of smart power grids, smart electricity meters are widely applied to industrial production and the life. For interests of the power supply and consumption parties, electricity meters are required to have high quality, precision and consistency. As temperatures vary considerably in south and north of China and electricity meters work in complex temperature environments, studies on the effects of temperature on power metering are of significant importance. In this paper, an optimization method considering the effects of temperature is proposed for the consistency of electricity meters. The precision consistency of electricity meters is optimized in full temperature range through means such as electrothermal coupling simulation, orthogonal test, cost calculation, etc., and the design scheme of electricity meters with maximum cost performance can be delivered for their manufacturers.
Research on the application of clustering and classification in battlefield damage identification
Authors: Song Mingchang , Shi Quan , Yin Shizhuang , Li Lei
Published: February 2021

This paper explores the solutions to the problem of battlefield damage pattern recognition. The main research results of the two components of clustering and classification are discussed respectively, and the main characteristics and existing problems of the existing methods are analyzed. The advantages, disadvantages and application scope of different methods are described in detail, which provides a basic theoretical guidance for the study of battlefield damage identification.
Brief Discussion on Evaluation & Demonstration of Operating Reliability of Safety-level I&C System Equipment in Nuclear Power Plant
Authors: Zhu Guixia , Qian Yugang , Lan Jian , Li Diliang , Zhou Tianmi , Hu Yuying
Published: February 2021

Safety-level system equipment is essential for the nuclear power plant either to complete the reactor emergency shutdown, containment isolation, reactor core cooling and heat emission from containment and reactor, either to prevent large amounts of radioactive substances from being released into the environment, and is also the focus of system equipment reliability management. As the safety-level system equipment has seismic requirements, in this paper, the operating reliability of safety-level I&C system equipment is evaluated and demonstrated, and the general process of reliability evaluation & demonstration is worked out.
Study on failure of transmission shaft based on finite element and fracture analysis technology
Authors: Xia Ming , Zhao Ke-lun , Zhao Hai-xin , Yang Jing
Published: February 2021

Due to the harsh driving environment, the power transmission components of military vehicles are subjected to long-term alternating loads and sudden impact loads. A failure analysis of the transmission shaft of a military truck was carried out. By constructing a mechanical simulation analysis model of the transmission shaft, the dynamic response of the structure under alternating stress and impact load is solved. Then the cause and mechanism of drive shaft failure were analyzed. Using fracture analysis technology to discuss the phenomenon of bearing sleeve cracking, circlip rupture and flange fork deformation. It indicates that caused by overload, foreign matter between the shaft and the needle etc., which ultimately leads to the failure of the universal joint transmission. Finally, the optimal design of the drive shaft is proposed.
A Fault Diagnosis Method based on Improved Synthetic Minority Oversampling Technique and SVM for Unbalanced Data
Authors: Han MingHong , Wu Yaman , Huang Yunfeng , Wang Yumin
Published: February 2021

Equipment usually breaks down suddenly and irregularly, so most of the data sets obtained for fault diagnosis have unbalanced characteristics, and the amount of data varies greatly from different fault types. In this paper, three problems in the application of synthetic minority oversampling technique (SMOTE) are studied, and the improved SMOTE algorithm combined with support vector machine (SVM) is proposed. The validity of the model is verified by CWRU bearing data compared with SVM and SMOTE+SVM methods, and the result of fault diagnosis is satisfactory.
Research on Reliability Life Evaluation of Torque Motor based on Performance Degradation
Authors: Ming Zhimao , Yang Jing , Zhao Kelun
Published: February 2021

The torque motor problem of reliability. The reliability evaluation of torque motor under the condition of accelerated degradation test is studied. Firstly, the failure mechanism of torque motor is studied, the performance degradation parameters are determined, then the theory of accelerated degradation test is described, the type of accelerated degradation model and the conditions of accelerated test are described. The method and procedure of product reliability analysis using accelerated degradation trajectory method under accelerated degradation test are studied. Finally, the reliability of a torque motor is evaluated and the average life value above 0.9 is calculated
Influence factors and identification of state-of-health for traction battery
Authors: Li D , Zhimao M , Mingsheng C , Jin D
Published: February 2021

According to state of health parameters and management system function, the properties of parameters are detailed to satisfy requirements of electric equipment for traction battery. The result shows that: many parameters, such as the ways of charge and discharge, temperature and state of charge, have apparently effect on state of health in propulsion battery. Battery cycle life reduces obviously when much depth of discharge is applied. Low temperature limits attenuation morphology of power battery. And high temperature weaken solid-electrolyte interface. Different types of battery agree with specific law during capacity reduction. Based on battery power, resistance and reduction characteristics, it should be considered in battery health management research, which includes identified parameters and accurate equivalent model.
A reliability evaluation method for RV reducer by combining multi-fidelity model and Bayesian updating technology
Authors: Jiang Z H , Zhang X L , Liu J Q
Published: February 2021

RV (rotating vector) reducer is a two-stage transmission mechanism composed of involute planetary gear transmission and cycloid gear transmission with small tooth difference. It is widely used in the transmission mechanism of industrial robots and CNC machine tools. Nonlinear dynamics of gear system is always an important and difficult problem, the randomness of manufacturing and assembly makes the dynamic response become more complex. In this paper, the stochastic dynamic response analysis and dynamic reliability estimation method is proposed for RV reducer. In this method, firstly, considering the uncertainties of manufacturing error and assembly error, the dynamic transmission performance is analyzed respectively using physical prototype test, virtual prototype simulation and theoretical model. Secondly, multifidly model and Bayesian theory are combined to estimate the statistical distribution and distribution parameters of the dynamic transmission error. Finally, the reliability of RV reducer is estimated, and the effects of uncertainties from manufacturing error and assembly error on the transmission accuracy are discussed.
GEOMETRIC UNCERTAINTY ANALYSIS OF A CENTRIFUGAL COMPRESSOR USING KRIGING MODEL
Authors: Li Shujiang , Huang Min , Liu Xuejun
Published: February 2021

Centrifugal compressor, which is an important turbomachinery, plays a significant role in the gas turbine engine. Various uncertain factors in the manufacturing process can lead to the geometric variations, which often cause noticeable variations in compressor performance. In this paper, a surrogate-based uncertainty analysis method is used to investigate the effect of geometric uncertainty on the aerodynamic performance of a centrifugal compressor. Firstly, a scaled-up version of NASA DDA’s 404-III centrifugal compressor is chosen as the research object. Considering the structural features of the compressor, a parameterized model with 38 independent control parameters is established to define the geometry of the compressor, enabling rapid modification of the geometry. Then, a widely-used simulation method based on computational fluid dynamics is employed to predict the aerodynamic performance at a series of specified geometries generated using Latin Hypercube Design. Next, based on the sample data, two Kriging models are built to emulating the complex functional relationship between the control parameters and the performance of compressor. Finally, a Kriging model-based Monte Carlo simulation method is used to perform the geometric uncertainty analysis. After specifying a reasonable probability distribution for each control parameter, the statistical distributions of the compressor performance are obtained and analyzed. The analysis results yield new insights for compressor designers.
Predicting workers’ unsafe workspace with fuzzy logic-based procedures; exploiting injury count in work hours
Authors: Adeyemi H O
Published: February 2021

Loss due to accident in any workspace is either material or personal and its associated with costs of damages to machines and also injuries, disabilities and death to workers. In this study, a fuzzy logic based expert system called Workspace Injury Sensitive Expert System (WISES) was developed to predict the unsafe level of any workspace. Two input variables, hours-worked” and “Injury-Rate were fired into the system’s Mamdani inference engine to generate the output as “Workspace-unsafe-ratings”. Data were collected from 20 workers in 20 workspaces and were run with WISES. The outcomes were compared with values obtainable using the existing Workplace Hazards Rating Mathematical Expression (WHRME). There existed a strong relationship (correlation coefficient of 0.710) between WISES and WHRME. The WISES had a statistically significantly lower level of rating (0.50 ± 0.02, SEM= 0.007), t(38) = 1.613, p = 0.115 compared to WHRME (0.60 ± 0.30, SEM=0.004) and the prediction capacity of both the systems were not significantly different. The developed expert system can find applications in any work environment that is prone to accident. It can also enhance the planning ability of managers and decision makers in industries when assessing workplaces and/or work methods disposed to accidents.
The ensemble of surrogate model based on local and global errors
Authors: Zhang X , Li H , Xiang G , Xu H W
Published: February 2021

The weight coefficient is the key factor for the success of the ensemble of surrogate model construction. In this paper, a method for constructing ensemble of surrogate model by combining local and global errors to calculate weight coefficient has been put forward. Radial basis function (RBF) and the Kriging model are built as the meta models, and the cross validation strategy is applied to calculate the global errors and the local errors of samples. The inverse proportion average method is used to calculate the weight coefficient by combining the local errors and global errors. In order to verify the effectiveness of the proposed method, two meta models and three methods to construct the ensemble of surrogate models are tested with six benchmark functions. The results show that the proposed method can improve the accuracy, robustness and universality of the surrogate model.
An Advanced Method of Collision Risk Assessment in terms of Encountering Ships
Authors: Deng Yuting , Zhang Weibin , Feng Xinyu
Published: February 2021

In the risk management of maritime transportation, near-miss collisions by ships comprise a significant risk. Under the background of intelligent transportation, the emergence of technologies such as unmanned driving put forward higher requirements for maritime risk detection models. Previous studies have rarely been able to adaptively estimate the risk of near-miss collisions in different situations, especially for rare but existing encounters. Given this, this paper aims to improve the Vessel collision risk operator (VCRO) and proposes an exponential model of the safety distance in terms of the imbalance of risk assessment in the case of ships meeting close to the safety zone. Then combining the two risk standards set in the ship collision risk operator, and considering the impact of relative speed and relative course on collision risk, the risk detection model is further improved. The simulation results show that the improved ship collision risk assessment model is more applicable and accurate for the detection of collision risk in the open sea.
Analysis of the influence of inductance and capacitance on film bulk acoustic wave filter
Authors: Peng C R , Liu G , Zhong H , Shi Y
Published: February 2021

Film bulk acoustic wave (BAW) filter is a kind of new type filter based on MEMS technology. And it has the advantages of high working frequency, simple manufacturing process, small size, integrating and has become a research hotspot in recent years. Compared with surface acoustic wave filter and ceramic dielectric filter, it has higher operating frequency and Q value. In this paper, the working principle of film bulk acoustic wave filter is briefly analysed, and ADS simulation software is used to further explore the influence of inductance and capacitance on its S parameter.
Atmospheric plasma: a simple way of improving the interface between natural polysaccharides and polyesters
Authors: Carette X , Mincheva R , Herbin M , Noirfalise X , Nguyen T C , Leclere P , Godfroid T , Kerdjoudj H , Jolois O , Boudhifa M , Raquez J
Published: February 2021

In this study, a novel simple and fast method was developed of immobilizing a natural polysaccharide (chitosan) on a polylactide (PLA) surface. In order to overcome the lack of surface adhesion between the chitosan and the PLA due to incompatibility issues, atmospheric pressure plasma was used. The plasma activation was able to modify the PLA surface by generating surface chemistry proper for stabilizing the chitosan layer. The activation of the surface was monitored through water contact angle (WCA) measurements and X-ray photoelectron spectroscopy (XPS). Indeed, the introduction of new functionalities lowers the hydrophobicity of the PLA surface allowing an effective spreading and immobilization of the chitosan layer. The presence of chitosan on the polyester’s surface was proven by Fourier transform infrared spectroscopy (FTIR).
Investigation of the deviation during the information transfer from the prosthetic field to the laboratory scanners
Authors: Galeva H. , Uzunov T. , Stoev Y. , Sofronov Y. , Todorov G.
Published: February 2021

The aim of this work is to investigate the deviations during the first stage of the information transfer from the prosthetic field to the dental laboratory scanners for CAD/CAM technology. The first upper left molar on an artificial acrylic resin dental model was prepared for full metal-ceramic crown according to the standard guidelines for step cut. The prepared prosthetic field was scanned by a high-precision industrial scanner with a 1-mm ruby ball stylus and a digital copy was made. With a standard tray, a two-phase two-stage silicon (A-silicone Zhermack hydrorise putty and light body) impression from the acrylic model was taken following the technology recommended by the manufacturer. The impression was powdered with dental stone type IV and a stone model was created 1 h after impression, the time delay taking place ordinarily in dental practice. Using the same measurement methods, the stone model’s surfaces were digitized. Both digital models were compared using the acrylic resin dental model as a reference. The results on the deviation during the transfer of information between the prosthetic field and the stone model represent the first level of inaccuracy in the CAD/CAM processing technology. The difference in the alteration of each dimension according to the reference and the stone model is not more than 20 μm in shrinkage or expansion direction. Thus, the widely used approach for information transfer using stone models from the prosthetic field to laboratory scanner for CAD/CAM technology could be considered as relevant with an accuracy of about ±10 μm. If the silicon impression is performed carefully, the stone models are sufficiently accurate representations of the prosthetic field and their digitalization in the dental laboratory is a reliable starting point for the CAD/CAM technology.
Optically-controlled density of alkali atom vapor for biomagnetic sensing applications
Authors: Tsvetkov S , Gateva S
Published: February 2021

Biomagnetic sensing is a powerful non-invasive tool for sensing the extremely small magnetic signals of living organisms. In recent years, the efforts to achieve higher resolution has brought about a demand for novel methods of increasing this tool’s sensitivity and further its miniaturization. In this paper, we present our studies on the optical control of the atomic vapor density in antirelaxation coated cells for application in optical magnetometry. A special system for homogeneous illumination of the cell walls is used to increase the atomic density, avoid the deposition of alkali atoms on the cell walls and reduce the coating deterioration.
Synthesis and characterization of polypyrrole-coated iron oxide nanoparticles
Authors: Lett J Anita , Sagadevan Suresh , Alshahateet Solhe F , Murugan Baranya , Jasni Ainil Hawa , Fatimah Is , Hossain M A Motalib , Mohammad Faruq , Oh Won Chun
Published: February 2021

Conducting polymers are gaining importance in recent years for their remarkable electrical and ionic properties and so, in order to further improve the fundamental properties, they are being integrated with iron oxide (Fe3O4) nanoparticles (NPs). Therefore, in the present study, polypyrrole (PPy) doped with iron oxide NPs to form PPy@Fe3O4 nanocomposite by adopting a simple chemical precipitation method of in situ polymerization. The various spectroscopic (UV–vis, FTIR, Raman, XRD, and XPS), and electron microscopic (FESEM and HRTEM) analysis were employed to study the effects of Fe3O4 NPs onto the polymer mixture. The analysis of results revealed the successful doping of Fe3O4 NPs onto the PPy polymer and also, the Raman spectral studies confirmed not only for the stabilization of doped nanocomposites in its polaronic form but also prevented from the auxiliary oxidation of polymer.
Research on the preparation method, microstructure and performance of hard silver plated/Cu-Cr0.6-Zr0.02 alloy contact
Authors: Shao Xinghai , Yang Qianqian , Liu Yuan , Zhao Molin , Wang Biao , Xu Yu , Wang Yao , Zhang Changle , Cao Lei
Published: February 2021

This paper developed a new type of disconnect switch contact with high-conductivity, oxidation resistance and wear resistance. Contact material and preparation were researched. The Cu–Cr–Zr alloy was prepared by vacuum induction melting, then the plate was obtained after rolling and aging strengthening. Contact sample was formed by die stamping, at last, a wear-resistant coating/Cu–Cr–Zr alloy switch contact was manufactured, after the silver antimony alloy hard coating was electroplated on the surface. In order to further study the Cu–Cr–Zr alloy and hard silver coating of the contact, microstructure analysis and performance testing are carried out. A large number of nano-sized pure Cr phases were found to exist in the Cu–Cr–Zr alloy matrix, and the material conductivity was 76.3% IACS. Compared with T2 copper, its mechanical properties and oxidation resistance were significantly improved, which helped to delay the corrosion progress of the substrate after the coating disappeared. The hard silver coating contains 1% of the alloy element Sb. Compared with the silver coating, its wear resistance was increased by 135.30%. Cu–Cr–Zr alloy and hard silver plating technology are effective for improving strength, corrosion resistance and wear resistance of contact.
In-line MRI-LINAC depth dose measurements using an in-house plastic scintillation dosimeter
Authors: Madden Levi , Roberts Natalia , Jelen Urszula , Dong Bin , Holloway Lois , Metcalfe Peter , Rosenfeld Anatoly , Li Enbang
Published: February 2021

Plastic scintillation dosimeters (PSDs) have many properties that make them desirable for relative dosimetry with MRI-LINACs. An in-house PSD, Farmer ionisation chamber and Gafchromic EBT3 film were used to measure central axis percentage depth dose distributions (PDDs) at the Australian MRI-LINAC Mean errors were calculated between each detector’s responses, where the in-house PSD was on average within 0.7% of the Farmer chamber and 1.4% of film, while the Farmer chamber and film were on average within 1.1% of each other. However, the PSD systematically over-estimated the dose as depth increased, approaching a maximum overestimation of the order of 3.5% for the smallest field size measured. This trend was statistically insignificant for all other field sizes measured; further investigation is required to determine the source of this effect. The calculated values of mean absolute error are comparable to the those of trusted dosimeters reported in the literature. These mean absolute errors, and the ubiquity of desirable dosimetric qualities inherent to PSDs suggest that PSDs in general are accurate for relative dosimetry with the MRI-LINAC. Further investigation is required into the source of the reported systematic trends dependent on field-size and depth of measurement.
Polydisperse inter-electrode plasma of Pd nanoclusters as a random cavity for x-ray spontaneous emission bursts
Authors: Smetanin I V , Kurilenkov Yu K , Oginov A V , Tarakanov V P , Samoylov I S
Published: February 2021

It is demonstrated experimentally that polydisperse Pd plasma of low energy (∼1 J) nanosecond vacuum discharge operating in a virtual cathode regime becomes an effective stochastic cavity in hard x-ray domain. A diffusion model of stochastic propagation of spontaneous x-ray radiation in the volume of randomly located reflecting clusters is developed also. The model provides qualitative explanation of both the experimentally observed effects of high-intensity bursts and partial ‘trapping’ of x-ray radiation. The x-ray burst emerges when photons are stored inside the plasma volume followed by instant release at the end of the discharge while the trapping regime corresponds to the slow developing x-ray diffusion with the characteristic time larger than the discharge duration. The results obtained are compared qualitatively with well-known concept of Letokhov’s random laser.
Random walks and community detection in hypergraphs
Authors: Carletti Timoteo , Fanelli Duccio , Lambiotte Renaud
Published: February 2021

We propose a one-parameter family of random walk processes on hypergraphs, where a parameter biases the dynamics of the walker towards hyperedges of low or high cardinality. We show that for each value of the parameter, the resulting process defines its own hypergraph projection on a weighted network. We then explore the differences between them by considering the community structure associated to each random walk process. To do so, we adapt the Markov stability framework to hypergraphs and test it on artificial and real-world hypergraphs.
Asymptotic expansions of eigenvalues by both the Crouzeix–Raviart and enriched Crouzeix–Raviart elements
Authors: Hu Jun , Ma Limin
Published: February 2021

Asymptotic expansions are derived for eigenvalues produced by both the Crouzeix-Raviart element and the enriched Crouzeix–Raviart element. The expansions are optimal in the sense that extrapolation eigenvalues based on them admit a fourth order convergence provided that exact eigenfunctions are smooth enough. The major challenge in establishing the expansions comes from the fact that the canonical interpolation of both nonconforming elements lacks a crucial superclose property, and the nonconformity of both elements. The main idea is to employ the relation between the lowest-order mixed Raviart–Thomas element and the two nonconforming elements, and consequently make use of the superclose property of the canonical interpolation of the lowest-order mixed Raviart–Thomas element. To overcome the difficulty caused by the nonconformity, the commuting property of the canonical interpolation operators of both nonconforming elements is further used, which turns the consistency error problem into an interpolation error problem. Then, a series of new results are obtained to show the final expansions.
The IgG3 subclass of β1-adrenergic receptor autoantibodies is an endogenous biaser of β1AR signaling
Authors: Mohan Maradumane L. , Nagatomo Yuji , Saha Prasenjit Prasad , Mukherjee Sromona D. , Engelman Timothy , Morales Rommel , Hazen Stanley L. , Tang W. H. Wilson , Prasad Sathyamangla V. Naga
Published: February 2021

β1-Adrenergic receptor autoantibodies are associated with deleterious consequences; however, the IgG3 subclass provides beneficial outcomes in human heart failure. IgG3 β1AR autoantibody inhibits G-protein coupling, simultaneously activating ERK through G-protein–independent arrestin-dependent mechanisms.
Computational modeling of chromosome re-replication in mutant strains of fission yeast
Authors: Novák Béla , Tyson John J.
Published: February 2021

A dynamic model is proposed for endoreplication cycles based on a limit-cycle oscillation generated by a transcriptional negative feedback loop, which is amplified by two positive feedbacks. Using phase plane techniques and bifurcation analysis, we show that the model accounts for the phenotype of various endoreplicating and overreplicating fission yeast mutants.
Predicting cell health phenotypes using image-based morphology profiling
Authors: Way Gregory P. , Kost-Alimova Maria , Shibue Tsukasa , Harrington William F. , Gill Stanley , Piccioni Federica , Becker Tim , Shafqat-Abbasi Hamdah , Hahn William C. , Carpenter Anne E. , Vazquez Francisca , Singh Shantanu
Published: February 2021

We created assays to quantify various readouts related to cell health, and then devised a machine learning method to predict those readouts using images from the cheap and fast Cell Painting assay. Because such images are publicly available, cell health annotations can now be readily added to thousands of drugs and genetic perturbations.