bluuebunny/crossref_metadata_2025 huggingface dataset:
Comparing the electric fields of transcranial electric and magnetic perturbation
Authors: Sheltraw D J , Inglis B , Labruna L , Ivry R
Published: March 2021

Significance. Noninvasive brain stimulation (NIBS) by quasistatic electromagnetic means is presently comprised of two methods: magnetic induction methods (transcranial magnetic perturbation or TMP) and electrical contact methods (transcranial electric perturbation or TEP). Both methods couple to neuronal systems by means of the electric fields they produce. Both methods are necessarily accompanied by a scalp electric field which is of greater magnitude than anywhere within the brain. A scalp electric field of sufficient magnitude may produce deleterious effects including peripheral nerve stimulation and heating which consequently limit the spatial and temporal characteristics of the brain electric field. Presently the electromagnetic NIBS literature has produced an accurate but non-generalized understanding of the differences between the TEP and TMP methods. Objective. The aim of this work is to contribute a generalized understanding of the differences between the two methods which may open doors to novel TEP or TMP methods and translating advances, when possible, between the two methods. Approach. This article employs a three shell spherical conductor head model to calculate general analytical results showing the relationship between the spatial scale of the brain electric fields and: (1) the scalp-to-brain mean-squared electric field ratio for the two methods and (2) TEP-to-TMP scalp mean-squared electric field ratio for similar electric fields at depth. Main results. The most general result given is an asymptotic limit to the TEP-to-TMP ratio of scalp mean-squared electric fields for similar electric fields at depth. Specific example calculations for these ratios are also given for typical TEP electrode and TMP coil configurations. While TMP has favorable mean-squared electric field ratios compared to TEP this advantage comes at an energetic cost which is briefly elucidated in this work.
Performance Metrics for Artificial Intelligence (AI) Algorithms Adopted in Prognostics and Health Management (PHM) of Mechanical Systems
Authors: Ochella Sunday , Shafiee Mahmood
Published: March 2021

Research into the use of artificial intelligence (AI) algorithms within the field of prognostics and health management (PHM), in particular for predicting the remaining useful life (RUL) of mechanical systems that are subject to condition monitoring, has gained widespread attention in recent years. It is important to establish confidence levels for RUL predictions, so as to aid operators as well as regulators in making informed decisions regarding maintenance and asset life-cycle planning. Over the past decade, many researchers have devised indicators or metrics for determining the performance of AI algorithms in RUL prediction. While most of the popularly used metrics like Mean Absolute Error (MAE), Root Mean Square Error (RMSE), etc. were adapted from other applications, some bespoke metrics are designed and intended specifically for use in PHM research. This study provides a synopsis of key performance indicators (KPIs) that are applied to AI-driven PHM technologies of mechanical systems. It presents details of the application scenarios, suitability of using a particular metric in different scenarios, the pros and cons of each metric, the trade-offs that may need to be made in choosing one metric over another, and some other factors that engineers should take into account when applying the metrics.
An Approach Based on Patterns for Synonymy Relations Detection
Authors: Tovar M , Flores-Petlacalco G , Reyes-Ortiz J A
Published: March 2021

Thesaurus, taxonomies, and ontologies are created as a way to represent knowledge. In recent years, the efforts to create them are focused on automatic knowledge extraction. For this purpose, research in the extraction of concepts and semantic relations is needed. Concepts or entities extracted from unstructured data has a became a challenge for the research communities. Texts, specifically, scientific papers contain knowledge where experts express their contributions to the science, including: techniques, methods and claims. In order to describe them, experts use synonyms, which are relevant to consider whereas it is desirable to extract such type of contribution form scientific text. This paper describes a method based on patterns for semantic relations extraction from scientific texts. The semantic relations correspond to synonymy. We describe pattern acquisition and relations extraction as phases to data evaluation. The evaluation shows promising results with 75% precision, 58% recall and 65% F-measure.
OpenVINO Deep Learning Workbench: Towards Analytical Platform for Neural Networks Inference Optimization
Authors: Demidovskij Alexander , Tugaryov Artyom , Kashchikhin Andrej , Suvorov Alexander , Tarkan Yaroslav , Mikhail Fedorov , Yury Gorbachev
Published: March 2021

Modern neural network methods make it possible to obtain qualitative results that open the colossal potential for integrating them into industrial applications. Therefore, there is a need for systems like the OpenVINO Deep Learning Workbench to analyze and optimize neural networks’ performance on target devices. As the primary tool for inference, the OpenVINO open environment is used, which provides a wide variety of options to speed up network execution on the target hardware.
Research on Contour Feature Extraction Algorithms for Arc-shaped Groove of Safety Seat Base
Authors: Liang Lipeng , Lu Yonghua , Zhu Huayu , Ye Zhibin , Chai Zhong
Published: March 2021

The spatial position of the seat base is complicated. The contour structure of arc groove is complex and its contour feature extraction is difficult. Aiming at the above problems, this paper presents an improved corner detection algorithm based on Curvature Scale Space (CSS), which uses adaptive local curvature and dynamic angle threshold to accurately extract corner points of arc groove contour. The correct corner positioning error of the algorithm proposed in this paper is only 0.99 pixel. The experimental results show that this method can effectively implement contour feature extraction.
TSW-FD: A Novel Temporal and Spatial Domain Weight Analysis of Feature Difference for Micro-Expression Spotting
Authors: Zhang Zhihao , Mo Fan , Zhao Ke , Chen Tong , Fu Xiaolan
Published: March 2021

The micro-expression spotting has recently attracted increasing attention from psychology and computer vision community, since embraced in the second facial Micro-Expression Grand Challenge (MEGC 2019). Different from the original feature difference (FD) analysis, in this paper, we proposed a novel temporal and spatial domain weight analysis of feature difference (TSW-FD) to achieve micro-expression spotting. The experimental results showed that TSW-FD improved 17.86% and 24.21% in F1-Score comparing to the FD in CASME II and SMIC-E-HS.
Unsupervised Mutual Mean Teaching with Heterogeneous Models for Person Re-Identification
Authors: Wang Wenlong , Wu Xiaofu , Zhang Suofei , Zhang Yuxin , Yan Jun
Published: March 2021

Person re-identification (Re-ID) aims at matching images of the same pedestrian under different cameras. State-of-the-art unsupervised domain adaptation (UDA) methods for person Re-ID transferred the learned knowledge from the source domain and further finetuned with pseudo-label target domain via clustering. To reduce the influence of noisy pseudo labels, the Mutual Mean-Teaching (MMT) framework was proposed by conducting pseudo label refinery to better model inter-sample relations in the target domain. Currently, MMT requires the use of the two same deep models for cooperative correction of noisy labels. In this paper, we extend the MMT framework to use two heterogeneous models for cooperative error correction. Experiments show that the proposed heterogeneous MMT framework can work well with two different deep models and its performance, however, is largely limited by the weaker model.
Algorithms for Modulation Recognition of Narrowband Power Line Carrier Communication Signals
Authors: Li Kun , Zhao Hongjun , Wang Yongjian
Published: March 2021

Automatic identification of modulated signals is an important technology of power line communication. Aiming at the problems of low signal recognition rate and characteristic parameter extraction in power line communication channel, this paper uses amplitude variance value of wavelet transform and higher order cumulant as the identification parameter, and designs a signal recognizer based on improved support vector machine. Under the condition of power line channel environment, the recognizer of this paper is less than the existing recognition method in the computational complexity, and has good robustness to power line noise. At the same time, it avoids the shortcomings of traditional neural network such as under-learning and over-learning. The simulation results show that when the SNR is 5 dB, power line communication signals through the recognizer, which the correct identification rate can reach 91%.
GSEMT: A Gene Set Enrichment Analysis Method Based on Mantel Test
Authors: Yu Na
Published: March 2021

Gene expression changes constantly with the occurrence and progression of diseases. The vast available gene expression data makes it possible for clinical researchers to understand the link between genotypes and phenotypes. However, it is still not an easy task because the information contained in the gene expression matrix is sparse. Gene set enrichment analysis is a powerful tool to meet the challenge of identifying complicated differential information underlying pathways. In this paper, we propose a method, called GSEMT, for gene set enrichment analysis by testing the correlation between a sample similarity matrix and a phenotype dissimilarity matrix. We implement experiments on knowledge-based gene sets and gene expression datasets for hepatocellular carcinoma. We justify the effectiveness and advantage of GSEMT by carrying out comparison studies. GSEMT outperforms GSEA and GSNCA in the classification performance on an experiment dataset and an independent validation dataset. The results show GSEMT is a useful alternative for gene set enrichment analysis.
Development of Multi-layer Soil Model for Yanmenguan Converter Station Based on Wenner and Magnetotelluric Method
Authors: Cheng Xiaosheng , Gao Jinwen , Feng Lijun , Hao Chenglong , Zhao Yuting , Cai Xinjing
Published: March 2021

In order to assess the effects of Yanmenguan HVDC grounding electrode on buried metal facilites, it is necessary to build up the soil model of Yanmenguan converter station. Soil resistivity was measures by Wenner and magnetotelluric method. Then the soil structure of Yanmenguan converter station was inversed based on the experimental data. It was shown that the soil structure of Yanmenguan converter station was three-layer horizental soil. The resisitivity of three layers was 101.7·m, 1037.5·m and 76.4·m. The thickness of three layers was 400m, 4600m and infinite.
A Low-bit And Data-conversion-free Memristive Spiking Computing Network
Authors: Qiao Guanchao , Hu Shaogang
Published: March 2021

Memristor crossbar holds promising potential in massively parallel data processing, as computing tasks beyond vector-matrix multiplication typically requires additional complex data conversion modules. In this work, we report a memristive spiking computing network (MSCN) without data conversion. Two memristor crossbars are used to perform vector-matrix multiplication, while spiking neurons are used to integrate the signals from each column of the memristor crossbars. Input and output signals are binary spikes (spiking or non-spiking); thus data conversions between the analog and digital domains are avoided. The MSCN is suitable for accelerating artificial neural network (ANN). A multi-layer perception (MLP) consisting of four layers is simulated based on the analog MSCN, and recognition accuracy of 98.55% under the MNIST test set is achieved. However, in the practical memristor, it is challenging to adjust conductance analogously and even challenging to implement multi-bit conductance states. Therefore, the memristor conductance states are further reduced to 3 bits and 1 bit. Encouragingly, recognition accuracies just slightly decrease to 98.36% and 97.96% for 3-bit and 1-bit conductance states, respectively, which is cost-effective considering the hardware reliability improvement.
Building a Catalogue of ISO/IEC 25010 Quality Measures Applied in an Industrial Context
Authors: Falco Mariana , Robiolo Gabriela
Published: March 2021

Measuring quality is extremely important while developing a software product, but there is a lack of knowledge of which are the ISO/IEC 25010 quality measures that are currently being used in the industry. Through a literature analysis of 27 studies, the present article introduces a catalogue of 269 quality measures applied in an industrial setting, which is formed by a subset of 81 metrics defined by GQM approach, a subset of 81 specific metrics for quality characteristics, and a subset of 86 metrics defined through ISO/IEC 25023 and 21 through IT-CISQ. In conclusion, it can be said that GQM is the most widely used method, regardless of standards. Likewise, Maintainability, Performance Efficiency and Usability are the quality characteristics that have shown the highest degree of interest because they are more receptive to the end user.
Virtual Streaming Computing Systems with Architecture Based on the Neural Network Information Model
Authors: Myshev A V , Slavin O A
Published: March 2021

The paper reveals the functional, structural and logical organization of new generation virtual streaming computing systems. Such systems allow realizing a new paradigm of computational intelligence and accessing new intelligent computing capabilities. The paradigm that allows realizing new advantages of virtual streaming computing systems is considered. These capabilities are implemented based on information models of a neural network and non-traditional principles for the development and implementation of various forms of computing. New forms of computing make it possible to control the mechanisms of parallelism, virtualization and intellectualization on the information dynamics of objects in the computing environment.
VoLTE problem location method based on big data
Authors: Chen Xinwei , Zhou Jun , Liu Keqing
Published: March 2021

This paper mainly introduces the key information extracting method from User Equipment (UE) test data, the synchronous algorithm of various interfaces X Detailed Record (XDR) data, the key information filling technique of multi interfaces X Detailed Record (XDR), the analytical procedure based on big data is descript in details. An example is given to explain that more accurate reason for Voice over Long-Term Evolution (VoLTE) call not connected can be found with big data from core network, compared with UE data only. With this method VoLTE problem can be quickly solved, it is very useful for wireless operator to improve the user voice service awareness rapidly.
Weight Calculation of GSM-R Network Quality of Service Evaluation Indexes Based on Analytic Hierarchy Process and Entropy Weight Method
Authors: Ma Liangde , Zuo Zihui , Zhao Bo , Li Lincan
Published: March 2021

In order to assign an objective and compre-hensive weight to each index for evaluating the GSM-R network quality of service, this paper used the combination of subjective and objective weight value to overcome the singularity of determining the weight from one aspect. The entropy weight method was used to determine the objective weight, which was assigned to each index by the entropy calculation. The subjective weight was calculated on the basis of the improved analytic hierarchy process (AHP) and the scale construction method was used to construct the judgment matrix, which reduced the computational complexity and redundancy. In addition, three kinds of calculation methods were proposed for combining multiple experts’ opinions. Combining the subjective and objective weight vectors obtained by different combination methods, the results of multiple integrated weight vectors were obtained. Then the average value was calculated for each index. By comparing the correlation coefficient between each integrated weight vector and the average weight vector, a better multiple combining calculation method was determined to calculate the weight of each index in the evaluation system. This paper combined the actual test data of ZX section of XL high-speed railway and the experts’ questionnaires to obtain the weight assignment of GSM-R network quality of service indexes. It can be seen from the results that the voice quality, switching success ratio and average handover delay account for a large proportion, which is in line with reality. The judgment method of weight proposed in this paper is objective and feasible.
Decision-making Algorithm for Improving the Lifetime of Signal Equipment
Authors: Dong Danyang , Yu Yi , Yuan Jianjun , Yilixiati Alimasi , Chu Pengzi
Published: March 2021

The safety of equipment operation is important for the operation of rail transits. The lifetime of equipment and its improvement methods have become one of the key issues in the operation and maintenance of rail transits. Based on the fuzzy comprehensive evaluation process and evaluation result data, the decision-making algorithm for improving the lifetime of the equipment was discussed, including the strategy recommendation algorithm based on assessed data and the strategy matching algorithm based on case reasoning. Taking the actual data of onboard ATC equipment of Line 11 in a city as an example, the effectiveness of the two methods was verified. The methods in the study can support the decision-making process for maintenance departments.
Analysis on Stress Screening of Components in Digital Background
Authors: Wei Juan , Sun Hongbo , Chen Jie
Published: March 2021

This paper introduces various common defects and corresponding screening methods of electronic components. Aiming at the temperature cycle and random vibration methods with good screening effect, the calculation formula of accelerating factor and screening strength in highly accelerated stress screening (HASS) test is introduced. Based on the above discussion, the stress screening test steps of electronic components are summarized to guide the selection of reasonable stress screening items and levels for electronic components.
A Very Lightweight Encryption Method Based on Multiple Substitution Tables
Authors: Henschen L , Lee J
Published: March 2021

We present a very lightweight encryption method based on multiple substitution tables. The method does not use sophisticated integer arithmetic and is therefore suitable for small embedded systems and other applications using simple processing elements. Plain text is encrypted one byte at a time. Each byte is replaced by the substitution element in the current table, and the plain text byte also determines the table to be used for the next byte. Encrypting and decrypting one byte involves only a table look-up, no arithmetic or bit manipulation. The same plain text byte has very small probability of being encrypted the same way twice in a row. We also present additional techniques for making the method secure against attacks when used in applications where the messages may have special or restricted forms.
Model for the Implementation of Security in Wi-Fi Networks for SMEs
Authors: Vega Diego , Lozano Andrés , Blanco Fabián , Simanca Fredys
Published: March 2021

In the last decades, the computerized handling of data has played a fundamental role in different economic areas, since there are several technological instruments that help to speed up a number of processes, so it is of utmost importance to learn how to use these tools, otherwise the information would be compromised. This paper aims to present a model for small and medium enterprises, through a pro-cess of identification and analysis of security measures in companies, based on the study of each company and in relation to the size of each organization, allow-ing to know the concepts of network monitoring that are applied in the creation of strong security policies for their facilities.
Analytical and Instrumental Framework for The Analysis and Resolution of Stakeholder Interest Conflict Using Cognitive Maps
Authors: Avdeeva Z K , Kovriga S V
Published: March 2021

The statement of the basic control problem of a situation with many active stakeholders using cognitive maps is presented. Approaches to the analysis and resolution of interest conflicts in such situations based on the basic control problem are proposed. These approaches make it possible to take into account different interests, identify contradictions and, if possible, find ways to overcome these contradictions by choosing different strategies for interaction between stakeholders. The problems systematization of conflict analysis and control in such situations at different phases of the conflict is presented. The systematization purpose is to organize monitoring, analysis and control of conflict situations using cognitive maps and scenario modeling tools based on them.
Public Sentiment Big Data Query Processing and Optimization with Unified Storage of Source and Meta Data
Authors: Yan Donglei , Li Jiaxin , Lei Shengnan , Tang Junri , Kou Kaiqi , Wang Zhiqiong
Published: March 2021

Public sentiment big data has the characteristics of mass, multi-source, heterogeneity and multi-mode. At present, it mostly adopts separate storage strategies and has low storage and query efficiency. To this end, a distributed storage model is proposed in which structured and unstructured data correspond and are stored uniformly. By establishing a unified storage framework for source metadata, the original source data and characteristic metadata are stored uniformly according to different storage methods. Based on the above storage architecture, a hierarchical index structure is proposed to improve the efficiency of big data query. The unified storage model of source metadata is compared with the common storage methods, and is in the leading position in terms of Block number and query processing efficiency.
Multi-user Fuzzy Keyword Searchable Encryption Scheme Based on Certificateless Cryptosystem
Authors: Yang Xiaodong , Wang Jiaqi , Tian Tian , Wang Xiuxiu
Published: March 2021

Nowadays, the application prospect of cloud storage is more and more extensive, and the security problem of cloud storage has become one of the hotspots of research. Searchable encryption can make full use of the huge computing resources of cloud servers and solve the problem of secure search after data encryption and upload. However, the existing searchable encryption schemes have the problems of high computational cost, low security, and insufficient flexibility in the way of searching keywords. In order to solve these problems, we propose a new certificateless multi-user fuzzy keyword searchable encryption scheme, which introduces the key distribution center, effectively reduces the computational cost, solves the problem of certificate management and key escrow, and uses the optimized wildcard technology to realize the fuzzy search of multiple users, which is not only brings convenience to users, but also realizes flexible search methods. Finally, the analysis results show that our scheme has indistinguishable security under keyword guessing attacks. Simulation experiments and performance analysis results show that our scheme has higher computational efficiency.
Identity-based Data Possession Verification Scheme for Multi-Replica Storage in Cloud
Authors: Yang Xiaodong , Wang Xiuxiu , Li Kaibing , Li Xixi
Published: March 2021

In the cloud storage environment, how to efficiently and dynamically complete the integrity verification of multi-user and multi-replica data is a challenging problem. Based on the bilinear mapping signature mechanism and the multi-branch authentication tree, we propose an identity-based integrity verification scheme of multi-replica data for cloud, which solves the problem of large public key storage and management overhead in signature algorithm based on traditional public key cryptosystems. The proof shows that our scheme satisfies the robustness and has the function of protecting privacy. The results of analysis indicate that, compared with the existing similar schemes, our scheme has higher communication efficiency and computing performance.
Computer-Based Testing Complex “Profvybir”: Occupational Guidance Diagnostics
Authors: Kravchenko Oksana , Shelenkova Nataliia , Mishchenko Maryna , Boichevska Ilona
Published: March 2021

The importance of occupational guidance for individuals has been highlighted in the article. Modern tasks and challenges of occupational guidance have been presented and conditions of a personality’s successful self-realization have also been analysed. The article deals with the application of modern methods and forms of occupational guidance for students. The authors present the results of approbation of the computer-based testing complex “ProfVybir”, performed during 2015-2019 for the diagnostics of occupational interests and inclinations. It is used as a separate information service for students of 8-11 grades. The complex was created in Centre of Psychological Diagnostics and Training Technologies “Insight” of Pavlo Tychyna Uman State Pedagogical University. During the mentioned period 780 students took part in occupational diagnostics. The following algorithm of work with the computer-based testing complex consisting of three blocks is presented. The article defines that the method of occupational guidance can be used to implement the policy of the Ministry of Education and Science in the development of occupational guidance, can be applied by a career advisor at school, while the computer-based testing complex may be an additional component of the occupational training program.
Are Open Textbooks Effective for Learning? Investigating the Issue of Human-computer Interaction in Pedagogical Design of Open Textbook Affordable for a Diversity of Learning Environments
Authors: Railean E A , Elci A , Ivanova M , Alias M , Bîrnaz N
Published: March 2021

This article discusses the impact of human-computer interaction in the pedagogical design of open textbooks affordable into a diversity of learning environments. An exploratory study is conducted, wherein an online questionnaire is administered to the second-year master’s degree students from the Faculty of Psychology and Educational Studies. The results show that students are aware of the importance of metacognition in developing effective learning strategies. Thus, they use metacognitive strategies when taking notes, doing reflections, and employing mnemonics to enhance understanding. However, despite the current practice of using open didactical materials, students feel that the open textbooks approach needs to be relooked and changed to be more effective; it could be equipped with appropriate learning tools to provide more opportunities for immediate feedback and collaborative assessment. Individualization and collaboration are the key factors in developing metacognitive experience. These findings indicate that students are cognizant of the important role of open textbooks in promoting learning.
Research on the Key Technology and System Architecture of Smart Research Travel in Novel Coronavirus Epidemic
Authors: Li Yanan , Bu Naipeng(Tom) , Kong Haiyan , Yin Zihan , Ji Xiuchao
Published: March 2021

In December 2019, China’s research travel market plummeted as a result of the novel coronavirus epidemic. In the context of a depressed research market in the Information Age, the concept of “Internet + research” emerged. First, according to symbiosis theory, the symbiotic units of smart research travel are determined. Then, based on a structural design of smart research travel data system, key technologies in big data, cloud computing, and Internet of Things are described in detail. Finally, based on the traditional browser/server architecture model of computers, a smart research travel system architecture suitable for the epidemic situation is constructed. The purpose of this study is to build a new ecology of research travel, optimize resource allocation, and promote the healthy, stable, and sustainable development of research travel in the country.
Optical Flow Monocular Visual-Inertial Odometry with Online Photometric Calibration
Authors: Liu Quanpan , Wang Zhengjie , Wang Huan
Published: March 2021

Kanade-Lucas-Tomasi (KLT) optical flow algorithm based on the brightness constancy assumption is widely used in visual simultaneous localization and mapping (SLAM) and visual odometry (VO). However, the automatic adjustment of camera exposure time, the attenuation factor of sensor irradiance caused by vignetting, and the nonlinear camera response function will cause the same feature point to have different brightness values on different image frames, thus breaking this assumption. Hence, we propose a gain-adaptive KLT optical flow algorithm with online photometric calibration, and on this basis, design a monocular visual-inertial odometry which is insensitive to brightness changes. This method can calibrate the photometric parameters online in real time, meet the assumption of constant brightness in practical applications, and make the algorithm more robust and accurate in the case of dynamic changes in brightness. Experimental results on the TUM Mono and EuRoC datasets show that the proposed algorithm can reliably calibrate the photometric parameters of any video sequence and perform well in the environment with varying brightness.
Backstepping Sliding Mode Control of Uncertainty Flexible Joint Manipulator with Actuator Saturation
Authors: Chen Hongyu , Dong Xiucheng , Yang Yong , Liu Jiutai
Published: March 2021

To address the issue of the flexible joint (FJ) manipulator control with actuator saturation, singular perturbation method is adopted in this paper which decompose the manipulator model into two subsystems in terms of time scale transformation, the fast one represents flexibility and the slow one expresses rigidity, and the control law of which is designed respectively. For the fast subsystem, a velocity-difference-based feedback control is designed to lower the oscillation caused by joint flexibility, while for the slow subsystem, the control performance of the system is enhanced by a combination of a class of nonlinear integral sliding surface and backstepping global sliding mode. The radial basis function (RBF) neural networks are utilized to compensate the actuator saturation, the disturbance and the modeled uncertainties. Based on the Lyapunov theory, the tracking convergence of the closed-loop system is proved rigorously. The simulation result shows that the designed control law can maintain good rapidity and accuracy, moreover, chattering is eliminated.
Numerical Simulation of Energy Distribution of Turbulent Vortices in Atmosphere Effects on Aircraft Wake Vortices
Authors: Zhou Jinxin , Li Dong , Zhang Zeyu , Pan Weijun
Published: March 2021

The effect of energy distribution of turbulent vortices in atmosphere on the evolution of wake vortices is studied using the numerical simulation approach. Solution-Based Dynamic adaptive mesh method is applied to compute the wake vortex evolution using FLUENT. Two series of cases are designed to study the role of larger and small-scale vortices in the decay of wake vortex, respectively. The results show that energy distribution of different scale vortices has a significant effect on the onset time of vortex linking and the decay rate of wake vortices at the turbulent diffusion phase and fast decay phase.
Target Detection in NAO Robot Golfing
Authors: Su Erwei , Chen Long , Xu Yingli , Hu Bin
Published: March 2021

In robot golfing games, how to identify and track small balls is a critical step for scoring. Considering uneven illumination and intensity, irregular distribution, and blurred borders, an integrated detection method based on the random Hough transform and the Kalman filter is presented to improve the recognition accuracy, i.e., guaranteeing the detection accuracy and the stability in shooting. Experiment on the NAO robot is performed to show the effectiveness of the proposed detecting method. Both theoretical and experimental results suggest that the proposed recognition method can reduce the calculation time of the Hough transform and has a certain degree of robustness against uncertain environments.
The Influence of Grid Scale on the Tail Vortex Capture of Aircraft
Authors: Zhang Zeyu , Li Dong , Zhou Jinxin
Published: March 2021

The grid has appreciable impact on the simulation of the wake vortex. There is a big difference between the traditional aerodynamic estimation grid and the grid used for capture the main parameters of the trailing vortex in the far field. This paper compares the similarities and differences between these two kinds of grids. The main parameters of the coarse grid are quite different from those of the refined grid simulation in the far field. Sufficient quantity grids are required to simulate the flow field in the parameters of wake vortex prediction. Otherwise, it may draw the reverse conclusions with the physical truth.
Research on Vibration Excitation Estimation of Warship Propulsion Shafting Based on Waveguide Theory
Authors: Wu Haiping , Yang Lihua , Liu Libin
Published: March 2021

The propeller excitation can be estimated by measuring the vibration response of the shafting, but there are many difficulties, such as difficult to implement, difficult to determine the boundary conditions and so on. For this reason, the waveguide model of different shaft segments on the shafting and the waveguide transfer relationship between the connected shaft segments are established based on the waveguide theory, and the waveguide coefficient is estimated combined with the vibration response observation data. The estimation of longitudinal oil film stiffness of thrust bearing and admittance of thrust bearing housing and hull connection structure is avoided, and the method of propeller longitudinal excitation based on waveguide transfer relation is verified by a specific example. The results show that the method is feasible and effective, and provides a new method for accurately grasping the actual propeller excitation.
Study on the Spatial Relationship between Green Space and Surface Runoff in Suzhou City
Authors: Li Shuangqi , Ma Jianwu , Bi Yu
Published: March 2021

Green spaces are more than just part of the landscape; they are a powerful means of purifying and controlling surface runoff. In the context of urbanization, Suzhou faces serious problems of water pollution, urban waterlogging and water shortage, and the main cause of these problems is the inadequate treatment of surface runoff. As an advanced city in the country, Suzhou still faces water ecology problems caused by surface runoff under high green space conditions, which makes it urgent to analyze the relationship between the existing green space and surface runoff to further discover the problems and deficiencies of the existing green space in reducing surface runoff, thus providing a basis for future green space system planning.
CFD Numerical Modelling of Spontaneous Combustion of Loose Coal in High Caved Area of Underground Roadway
Authors: Yang Jianhui , Lei Yajun , Li Hucun , Yang Biao , Wang Zhenxing
Published: March 2021

Coal fires are serious health and safety hazards throughout the world. In underground, coal spontaneous combustion process often starts with the inside of coal, which makes it difficult to determine the ignition point. For example, the coal fire happened in high caved area of roadway is often hard to be noticed. Once the smoke appears, it has already been late to take control measures. In this paper, Simulation analysis of microcirculation flow field velocity distribution, temperature distribution and the possible distribution of the coal spontaneous combustion zone are preformed which could provide a good scientific and reasonable understanding of the fire risk due to microcirculation in loose coal in underground roadway.
Application of Water Quality Index in the Evaluation of an Abandoned Mine Areas of Xunwu, China
Authors: Yin Shiyun , Liu Zuwen , Yang Shi , Lin Yuan
Published: March 2021

Within the display think about, an surrendered ion-type rare soil mine contains a tremendous affect on the encompassing water environment contamination in Xunwu, Jiangxi Province, China. Since the usage of coordinates remediation innovation and extend in 2018, its natural quality has been enormously moved forward. In arrange to encourage assess the environmental remediation impact, a altered water quality index strategy (WQI) is proposed. Concurring to the grid method, 16 water quality examining focuses were set within the surrendered mine remediation extend, and 9 key assessment records such as NH4
+-N and heavy metals were chosen for principal component analysis (PCA) and factor analysis (FA), in arrange to comprehensively assess the worldly and spatial changes of different contamination variables within the deserted mine environmental remediation range. The results uncovered that the water quality of the surface water has been slowly progressed, and the generally water quality has been getting superior, among which the water quality in August is clearly superior than that in July, and the progressed water quality index is successful for the classification of water quality and the assessment of the transient and spatial changes of water quality within the remediation of surrendered mines.
Developing a Calcium Silicate Prefabricated Board Ventilated Wall for Building Energy Efficiency Retrofit in Hot-Humid Areas
Authors: Jin Xueli , Wang Junsong , Meng Qinglin
Published: March 2021

Ventilated wall is considered as an effective technique for building energy efficiency retrofit in hot-humid areas, and the heat exchange inside the ventilated layer blocks the heat gain into the wall. Most current researches focus on the performance assessment of the wall system but lack the optimize design of the external board. Here we demonstrated a new type of ventilated wall, using the calcium silicate material as the cladding panel for its excellent physical properties and easy installation and maintenance. In particular, the aluminum foil was attached to the interior side of the board to further lower the emissivity for achieving a better insulation effect. Based on the field experiment in summer days, the thermal performance of the new type of ventilation wall was obtained and further compared with the conventional wall. Moreover, the equivalent thermal resistance of this novel ventilated wall was also calculated. The results revealed that: the interior wall surface temperature and energy consumption of the new ventilated wall proposed was about 3-5°C and 39.2% lower than those of the conventional wall, respectively. The low emissivity significantly insulated the heat transfer inside the cavity. In parallel, the calculated equivalent thermal resistance of the ventilation wall (0.971m2⋅K/W) was also 2.07 higher than that of the conventional wall.
Pilot Study on Catalyzed Oxidation-Ceramic Membrane-High Pressure Reverse Osmosis for Desulfurization Wastewater Recovery
Authors: Wu Zhongjie , Hou Yaqin , Li Xinmei , Li Yanping , Cao Hongmei
Published: March 2021

With the increasing pressure of environmental protection, the zero-discharge project construction of power industry was speeding up. However, the unstable operation of equipment was often occured. With regard to this, the process of catalytic ozonation-ceramic membrane-high pressure reverse osmosis for desulfurization wastewater reuse was established in Huaneng Yunhe Power Plant. The amount of catalyst was firstly evaluated and the COD could be reduced from 264 ppm to 107 ppm. Even after the ozone catalytic oxidation process continuously operated for more than 20 days, the catalytic efficiency of the catalyst was still maintained at the original level. The operating pressure of the ceramic membrane was maintained at 0.17 MPa, and the wastewater recovery rate was more than 90 %. Moreover, the membrane flux of the ceramic membrane after backwashing could be recovered well. The desulfurization wastewater treated by catalytic ozonation process and ceramic membrane process was reused in the high pressure reverse osmosis unit. The operating pressure was maintained at 1.21 MPa and the water recovery could reach about 55%. The overall water recovery rate of ozonation ceramic membrane reverse osmosis process was 50%. The operation efficiency of each treatment unit was high and stable, and the performance recovery effect was excellent after the decline of membrane flux, which improved the operation stability of the whole treatment process.
Numerical Investigation on Flow Characteristics in the Horizontal Elbow Suction Pipe Connected to Sumps of Large-Scale Pumping Stations
Authors: Zhang Yetian , Feng Jianjun , Ge Zhenguo , Zhu Guojun , Wu Guangkuan
Published: March 2021

To know the flow characteristics in the horizontal elbow suction pipe connected to sumps of large-scale pumping stations, the distribution of air-entraining vortex and water velocity is studied using ANSYS CFX with considering the gravity. The Volume of Fluid (VOF) method is adopted to track the water level of the sump. The results show that a typical funnel-shaped continuous air-entraining vortex is observed via the air volume fraction. Its size gradually increases from the inlet to outlet of the suction pipe. The pressure changes linearly with the water depth under the effect of gravity whereas the velocity shows non-uniform distribution. The axial velocity distribution of the outlet is non-uniform in the radial direction, which is analogous to the velocity distribution. In addition, the centre wall of the suction pipe outlet may affect remarkably the velocity distribution.
The Influence of Anti-Cavitation Edge on the Hydraulic Performance of Bulb Tubular Turbine
Authors: Fu Yongyuan , Wu Guangkuan , Feng Jianjun , Zhu Guojun
Published: March 2021

In engineering applications, anti-cavitation edges are often added at the blade’s suction surface. The internal flow field of the bulb tubular turbine is numerical simulated using ANSYS CFX-19.2 to understand the influence of the anti-cavitation edge. Four geometric models are adopted for investigation, i.e., no anti-cavitation edge, 2mm, 3mm and 4mm thickness anti-cavitation edge. The results show that the efficiency of the runner increases with the anti-cavitation edge. As the thickness of the anti-cavitation edge increases, the clearance flow rate decreases. The clearance leakage vortex is pushed away from the blade’s suction surface and its inception is far away from the blade’s inlet. Moreover, the strength for clearance leakage vortex decreases under the effect of the anti-cavitation edge, which reduces the damage to the runner blade.
Study on Optimization of Control Strategy for Pump Shutdown in Pumped-Storage Unit
Authors: Bi Zhiwei , Wei Jiafu , Zhao Bushi , Hou Kai , Zhang Yike , Zhang Yuncheng , Chen Shengsheng
Published: March 2021

In view of the formulation of power failure control strategy of pumped-storage unit at pump operation condition caused by hydraulic, mechanical and electrical factors, taking Heimifeng pumped-storage power station as an example, downtime control strategy at the pump working condition were analyzed under different heads. The transition characteristics at the pump condition of power outage for different guide vane opening were discussed. The stability parameter variation characteristics for the key points of vibration/sway and pressure pulsation at the process of shutdown were analyed. Combination the GCB characteristics of unit, the optimal load and the guide vane opening in the power outage process of shutdown at pump working condition were determined, and the electric life. The optimized shutdown strategy can ensure the safe operation of the unit, and the shutdown load can meet the requirements of the industry standard.
Research and Application on Numerical Simulation of Hydraulic Transients in Complex Water Conveyance System
Authors: Zhou T C , Li G H , Chen X R , Wu X M , Pan Y B
Published: March 2021

Accurate simulation of hydraulic transients is crucial and complicated in the design of hydropower station and pumped storage power station. In this paper, key technologies for hydraulic transient simulation calculation in complex water conveyance system were studied. The structural matrix method with advantages of high accuracy and fast speed for numerical calculation was introduced. Complicated elements in the conveyance system were refined, such as high precision simulation of differential surge chamber, simulation of long and narrow upper chamber, new interpolation method for characteristic curve of pumped storage unit. Based on Jinping II hydropower station with special long headrace system and differential surge chamber, Baihetan hydropower station with complex tailrace system and large surge chamber and Xianyou pumped storage power station with complex unit characteristics and various working conditions, the application of the simulation software HYSIM in field test and inversion calculation was illustrated. The paper providing references for the design of similar projects.
Research and Development of Management and Control System for Lake Sediment Improvement and Dehydration Treatment
Authors: Liu Gongxun , Liang Xin , Zhang Qingbo , Liu Ruoyuan , Hong Guojun , Zheng Shihua , Zhong Huangliang , Liu Kuilong
Published: March 2021

Relying on the water environment improvement project of Wuhan East Lake, an intelligent management and control system for river and lake sediment dredging and solidification treatment is developed based on the integrated treatment technology of sediment dredging and solidification. The system is mainly composed of dredging vessel positioning and digging depth monitoring subsystem, dehydration and drying integrated optimization control subsystem, safety monitoring subsystem, earthwork automatic measurement subsystem and comprehensive management subsystem. Through real-time monitoring, collection and analysis of data, from the real-time adjustment of dredger construction parameters to the matching of quality and process parameters of plate and frame machine pressure filtration, and then to the whole life cycle of earthwork automatic measurement and comprehensive efficiency, cost analysis, personnel situation, project progress and production safety, comprehensive intelligent operation and control is realized. The system has been successfully applied to the water environment improvement project of Wuhan East Lake and achieved remarkable results. It not only ensures the quality of sediment dredging and drying treatment, but also greatly improves the production efficiency and ensures the production safety. Through real-time monitoring, collection and analysis of data, from the real-time adjustment of dredger construction parameters to the matching of quality and process parameters of plate and frame machine pressure filtration, and then to the whole life cycle of earthwork automatic measurement and comprehensive efficiency, cost analysis, personnel situation, project progress and production safety, comprehensive intelligent operation and control is realized. The system has been successfully applied to the water environment improvement project of Wuhan East Lake and achieved remarkable results. It not only ensures the quality of sediment dredging and drying treatment, but also greatly improves the production efficiency and ensures the production safety.