Lining Shen, Bing Xiong and Jiming Hu
The purpose of this paper is to analyze the research status and outputs of information behavior in China in order to reveal its in-depth research pattern and trends.
Abstract
Purpose
The purpose of this paper is to analyze the research status and outputs of information behavior in China in order to reveal its in-depth research pattern and trends.
Design/methodology/approach
The author collected literature during the past 29 years from China Academic Journal Network Publishing Database. Bibliometric analysis, including publication growth analysis, core authors and collaborative degree analysis, core journals analysis, and institutions distribution, was performed. The temporal visualization map of burst term was drawn, and the co-occurrence matrix of these keywords was analyzed by the hierarchical cluster analysis, strategic diagram, and social network analysis.
Findings
The earliest article on information behavior in China was published in 1987. And the number of articles has risen continually since then, which follows the logical growth law of literature. The collaborative degree of authors is on the rise in general. The distribution of these articles obeys the Bradford’s Law of Scattering. School of Information Management of Wuhan University remarkably ranks the top in most publications. In all, ten important research directions were identified, which are in the imbalanced development. And a newly appearing topic with great potential for further development, namely information seeking and information security, is identified.
Originality/value
This study provides important insights into the research status and trends on information behavior in China, which might provide a potential guide for the future research.
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Keywords
Auxiliary power system is an indispensable part of the train; the auxiliary systems of both electric locomotives and EMUs mainly are powered by one of the two ways, which are…
Abstract
Purpose
Auxiliary power system is an indispensable part of the train; the auxiliary systems of both electric locomotives and EMUs mainly are powered by one of the two ways, which are either from auxiliary windings of traction transformers or from DC-link voltage of traction converters. Powered by DC-link voltage of traction converters, the auxiliary systems were maintained of uninterruptable power supply with energy from electric braking. Meanwhile, powered by traction transformers, the auxiliary systems were always out of power while passing the neutral section of power supply grid and control system is powered by battery at this time.
Design/methodology/approach
Uninterrupted power supply of auxiliary power system powered by auxiliary winding of traction transformer was studied. Failure reasons why previous solutions cannot be realized are analyzed. An uninterruptable power supply scheme for the auxiliary systems powered by auxiliary windings of traction transformers is proposed in this paper. The validity of the proposed scheme is verified by simulation and experimental results and on-site operation of an upgraded HXD3C type locomotive. This scheme is attractive for upgrading practical locomotives with the auxiliary systems powered by auxiliary windings of traction transformers.
Findings
This scheme regenerates braking power supplied to auxiliary windings of traction transformers while a locomotive runs in the neutral section of the power supply grid. Control objectives of uninterrupted power supply technology are proposed, which are no overvoltage, no overcurrent and uninterrupted power supply.
Originality/value
The control strategies of the scheme ensure both overvoltage free and inrush current free when a locomotive enters or leaves the neutral section. Furthermore, this scheme is cost low by employing updated control strategy of software and add both the two current sensors and two connection wires of hardware.
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Keywords
Hui Xiong, Youping Chen, Xiaoping Li, Bing Chen and Jun Zhang
The purpose of this paper is to present a scan matching simultaneous localization and mapping (SLAM) algorithm based on particle filter to generate the grid map online. It mainly…
Abstract
Purpose
The purpose of this paper is to present a scan matching simultaneous localization and mapping (SLAM) algorithm based on particle filter to generate the grid map online. It mainly focuses on reducing the memory consumption and alleviating the loop closure problem.
Design/methodology/approach
The proposed method alleviates the loop closure problem by improving the accuracy of the robot’s pose. First, two improvements were applied to enhance the accuracy of the hill climbing scan matching. Second, a particle filter was used to maintain the diversity of the robot’s pose and then to supply potential seeds to the hill climbing scan matching to ensure that the best match point was the global optimum. The proposed method reduces the memory consumption by maintaining only a single grid map.
Findings
Simulation and experimental results have proved that this method can build a consistent map of a complex environment. Meanwhile, it reduced the memory consumption and alleviates the loop closure problem.
Originality/value
In this paper, a new SLAM algorithm has been proposed. It can reduce the memory consumption and alleviate the loop closure problem without lowering the accuracy of the generated grid map.
Details
Keywords
Hui Xiong, Youping Chen, Xiaoping Li and Bing Chen
Because submaps including a subset of the global map contain more environmental information, submap-based graph simultaneous localization and mapping (SLAM) has been studied by…
Abstract
Purpose
Because submaps including a subset of the global map contain more environmental information, submap-based graph simultaneous localization and mapping (SLAM) has been studied by many researchers. In most of those studies, helpful environmental information was not taken into consideration when designed the termination criterion of the submap construction process. After optimizing the graph, cumulative error within the submaps was also ignored. To address those problems, this paper aims to propose a two-level optimized graph-based SLAM algorithm.
Design/methodology/approach
Submaps are updated by extended Kalman filter SLAM while no geometric-shaped landmark models are needed; raw laser scans are treated as landmarks. A more reasonable criterion called the uncertainty index is proposed to combine with the size of the submap to terminate the submap construction process. After a submap is completed and a loop closure is found, a two-level optimization process is performed to minimize the loop closure error and the accumulated error within the submaps.
Findings
Simulation and experimental results indicate that the estimated error of the proposed algorithm is small, and the maps generated are consistent whether in global or local.
Practical implications
The proposed method is robust to sparse pedestrians and can be adapted to most indoor environments.
Originality/value
In this paper, a two-level optimized graph-based SLAM algorithm is proposed.
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Keywords
Xiao Bing, Jiang Yan and Jin Hongbin
The purpose of this paper is to present an approach which can evaluate the ability that successfully achieves command and control, both in qualitative and quantitative modes, to…
Abstract
Purpose
The purpose of this paper is to present an approach which can evaluate the ability that successfully achieves command and control, both in qualitative and quantitative modes, to improve decision accuracy and speed, as well as construct an executable architecture for analyzing and verifying different decision projects.
Design/methodology/approach
By defining command and control (C2) decision architecture and decomposing C2 decision processes into measurable subfunctions, measures and metrics will be associated with each of the lowest level decomposed functions, and will be used to provide support for performance evaluation. Both Markov decision process analysis and conditional probability (CP) logic are used for modeling the decision‐making process of course of action (COA). Meanwhile, an executable architecture constructed by Petri net is applied to logic structural verification and performance evaluation.
Findings
The paper presents an idea and methodology for net‐centric command and control decision‐making process analysis.
Research limitations/implications
The paper describes and decomposes C2 decision processes for complex missions in uncertain environments.
Practical implications
The paper could be an important reference of analysis and application in net‐centric command and control of decision making.
Originality/value
The paper combines methodology with qualitative methods (decision process decomposition), quantitative method (Markov decision process analysis and CP logic), as well as structural verification and performance evaluation.
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Keywords
Xiong Liang, Bing Li, Xiaoyu Wu, Hongyan Shi, Kun Zeng and Yatao Wang
The purpose of this paper is to present a method for ultrasonically molding polymer powder in a micro plastic part mold. In the method, a printed circuit board (PCB) in which…
Abstract
Purpose
The purpose of this paper is to present a method for ultrasonically molding polymer powder in a micro plastic part mold. In the method, a printed circuit board (PCB) in which micro‐hole arrays are drilled is used as a micro cavity insert. With the utilization of ultrasonic vibration, the polymer powder, which is prefilled and compacted in a micro cavity, mutually generates great sliding friction heat so as to be rapidly plasticized and molded.
Design/methodology/approach
Micro carbide drill bits of which the diameters are 100.0 μm, 150.0 μm and 200.0 μm, respectively, are used for drilling the PCB to form a micro‐hole array insert. Next, two kinds of various ultra‐high molecule weight polyethylene (UHMW‐PE) powder with various grain diameters are directly filled into a charging barrel and a mold cavity with the micro‐hole array insert. Proper process parameters are set on ultrasonic plasticizing and molding equipment so that a molding test can be performed. The melt of UHMW‐PE can be rapidly filled into the cavity. Finally, micro‐column array plastic parts are successfully prepared.
Findings
The micro‐hole array PCB is a mold insert which is quite applicable for the ultrasonic molding of the powder in the mold. When a molding material is the coarse UHMW‐PE powder with the grain diameter of about 350 μm, the diameter replication rates of the micro‐column array plastic parts become good in order with the increased micro‐hole diameter of the PCB. When the fine UHMW‐PE powder with the grain diameter of about 80 μm is adopted, the diameter replication rates of the micro‐column array plastic parts become good in order with the decreased micro‐hole diameter of the PCB.
Originality/value
In this paper, the micro‐column array plastic parts with good replicability are successfully prepared by a technique for ultrasonically plasticizing and molding in the cavity. The technique can be applied to the fields of medical treatment, communication, optics, chemistry and so on, such as biological micro needle arrays, micro biological chips, optical memories, and micro chemical reaction chips.
Details
Keywords
Xiong Liang, Bing Li, Lianyu Fu, Xiaoyu Wu, Hongyan Shi, Taijiang Peng and Bin Xu
This paper aims to present the main factors affecting the mechanical drilling of the printed circuit board (PCB for short) micro-holes and method of micro-ultrasonic powder…
Abstract
Purpose
This paper aims to present the main factors affecting the mechanical drilling of the printed circuit board (PCB for short) micro-holes and method of micro-ultrasonic powder molding (micro-UPM for short) by utilizing PCB micro-hole array.
Design/methodology/approach
To optimize the drilling process, the paper proposes the on-line monitoring methods for the drilling process including drilling force, drilling temperature, high-speed photography and vibration signals. Taking 0.10 and 0.15 mm micro-drilling as examples, the paper analyzes the drilling process of ultra-small micro-holes. Finally, by taking the PCBs with 0.10 and 0.15 mm micro-hole arrays as the micro-cavity inserts, utilizing ultra-high-molecule weight polyethylene powder with the average particle size of about 150 μm as raw material, two sizes of micro-cylinder array polymer parts are fabricated through micro-UPM process.
Findings
PCB micro-cavity inserts with micro-hole arrays fabricated by mechanical drilling has the advantages of low costs, high efficiency and good consistency. Taking 0.10 and 0.15 mm micro-drilling as examples, it is found that the both measured apertures are about 10.0 μm more than the diameter of the micro-drill bits on average. The average diameter of the micro-cylinders by micro-UPM process is smaller than that of the micro-hole with the same specification, while the value of the roughness of the cylinder surface is more than that of the hole-wall surface with the same specification.
Originality/value
This paper describes the challenges and the developments of mechanical drilling and by using PCB micro-cavity inserts with micro-hole arrays fabricated by mechanical drilling, two different micro-cylinder array polymer parts are successfully made and thus the application area of PCB micro-drilling is broadened.
Details
Keywords
Xiong‐hui Cai, Bing An, Feng‐shun Wu and Yi‐ping Wu
The purpose of this paper is to accomplish the low cost mass‐production of flexible radio frequency identification (RFID) tag inlays.
Abstract
Purpose
The purpose of this paper is to accomplish the low cost mass‐production of flexible radio frequency identification (RFID) tag inlays.
Design/methodology/approach
An anisotropic conductive paste (ACP) is prepared by mixing uniform micro‐sized spherical conductive particles, latent curing agent and other additives into a thermoset epoxy resin. RFID tag inlays are assembled with the paste through flip‐chip technology. The microstructural analysis of bonded joints, bond strength testing, and high‐temperature and humidity aging testing are employed to evaluate the performance of the inlays.
Findings
It was found that the chips are hard assembled on the antennae by the ACP. Flexible RFID tag inlays assembled using the presented method have good reliability when working under high frequency (13.56 MHz) conditions.
Research limitations/implications
The method presented is a promising new way for packaging flexible RFID tag inlays with ACP. Through the use of flip‐chip technology, large‐scale production is possible with low manufacturing costs.
Originality/value
The paper details a simple way to prepare an anisotropic conductive paste and to assemble flexible RFID tag inlays. The technique uses flip‐chip technology with the paste as the electrical and mechanical interconnection material. It presents a simple and fast method of assembly for flexible RFID tag inlays on a large‐scale with low cost.
Details
Keywords
Junguo Wang, Jianzhong Zhou and Bing Peng
The purpose of this paper is to detect the periodic signal under strong noise background, and estimate its amplitude/phase.
Abstract
Purpose
The purpose of this paper is to detect the periodic signal under strong noise background, and estimate its amplitude/phase.
Design/methodology/approach
Melnikov method is adopted as calculating the threshold value when chaos occurs, and the detected signal is taken as a system parameter. The system's output state is changed if the parameter has a slight change near the threshold. Meantime, the phase of system's output is recognized to judge whether the output state changes, and the signal parameter is estimated according to the necessary condition.
Findings
A small periodic signal in noise can be detected by Duffing oscillator via a transition from chaotic motion to periodic motion.
Research limitations/implications
The paper shows how to calculate the amplitude/phase in low signal‐to‐noise ratios.
Practical implications
The Duffing system is sensitive to the weak periodic signal and has definite immunity to noise, so it is easy to construct a system composed of many oscillators that could process complex signals, even though the environmental noise is intense.
Originality/value
This paper presents a nonlinear method for detecting and extracting the weak signal.
Details
Keywords
Wang Junguo, Zhou Jianzhong and Peng Bing
The purpose of this paper is to improve forecasting accuracy for short‐term load series.
Abstract
Purpose
The purpose of this paper is to improve forecasting accuracy for short‐term load series.
Design/methodology/approach
A forecasting method based on chaotic time series and optimal diagonal recurrent neural networks (DRNN) is presented. The input of the DRNN is determined by the embedding dimension of the reconstructed phase space, and adaptive dynamic back propagation (DBP) algorithm is used to train the network. The connection weights of the DRNN are optimized via modified genetic algorithms, and the best results of optimization are regarded as initial weights for the network. The new method is applied to predict the actual short‐term load according to its chaotic characteristics, and the forecasting results also validate the feasibility.
Findings
For the chaos time series, the hybrid neural genetic method based on phase space reconstruction can carry out the short‐term prediction with the higher accuracy.
Research limitations/implications
The proposed method is not suited to medium and long‐term load forecasting.
Practical implications
The accuracy of the load forecasting is important to the economic and secure operation of power systems; also, the neural genetic method can improve forecasting accuracy.
Originality/value
This paper will help overcome the defects of traditional neural network and make short‐term load forecasting more accurate and fast.