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28 February 2019, Volume 24 Issue 1 Previous Issue    Next Issue

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Resonance Characteristics of Piezoelectric Resonator Based on Digital Driving Circuit of Field-Programmable Gate Array WANG Zhenyu (王振瑜), WU Xiaosheng * (吴校生), SHU Shengzhu (叔晟竹) 2019, 24 (1):  1-6.  doi: 10.1007/s12204-019-2034-1 Abstract ( 583 )   PDF (5961KB) ( 174 )   Piezoelectric resonators are widely used in frequency reference devices, mass sensors, resonant sensors (such as gyros and accelerometers), etc. Piezoelectric resonators usually work in a special resonant mode. Obtaining working resonant mode with high quality is key to improve the performance of piezoelectric resonators. In this paper, the resonance characteristics of a rectangular lead zirconium titanate (PZT) piezoelectric resonator are studied. On the basis of the field-programmable gate array (FPGA) embedded system, direct digital synthesizer (DDS) and automatic gain controller (AGC) are used to generate the driving signals with precisely adjustable frequency and amplitude. The driving signals are used to excite the piezoelectric resonator to the working vibration mode. The influence of the connection of driving electrodes and voltage amplitude on the vibration of the resonator is studied. The quality factor and vibration linearity of the resonator are studied with various driving methods mentioned in this paper. The resonator reaches resonant mode at 330 kHz by different driving methods. The relationship between resonant amplitude and driving signal amplitude is linear. The quality factor reaches over 150 by different driving methods. The results provide a theoretical reference for the efficient excitation of the piezoelectric resonator. References | Related Articles | Metrics

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Gain Properties of Triply-Doped Graphene-Insulator-Graphene Nanosheet Waveguide KHUSHIK Muhammad Hanif Ahmed Khan, JIANG Chun *(姜淳) 2019, 24 (1):  7-11.  doi: 10.1007/s12204-019-2035-0 Abstract ( 351 )   PDF (382KB) ( 125 )   Er3+-Tm3+-Pr3+ triply-doped graphene-glass-graphene (GGG) nanosheet waveguide amplifier, which is a promising candidate for integrated photonic devices, is modelled and numerically analyzed. The designed waveguide is composed of a triply-doped tellurite glass core. The core is sandwiched between two graphene layers. The rate and power propagation equations of a heterogeneous multi-level laser medium are set up and solved numerically to study the effects of waveguide length and active ion concentrations on amplifier performance at five different input signal wavelengths (1.310, 1.470, 1.530, 1.600 and 1.650 μm). The analytical results show that rareearth ion dopant concentrations at an order of 1026 ion/m3, waveguide length at 0.1m and pump power at 100mW can amplify 1.530 and 1.600 μm input signals with 1 μW power up to approximately 20.0 and 24.0 dB respectively. Finite-difference time-domain (FDTD) simulation results show that mode field radius of GGG waveguide is smaller than that of silicon waveguide. Consequently, GGG waveguide with the same pump and signal power and the same gain-medium length can produce higher gain than silicon waveguide. References | Related Articles | Metrics

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Effect of Electron Beam Irradiation on Thermal and Mechanical Properties of Polyamide Copolymer/Multiwall Carbon Nanotube Composites CUI Chengwen (崔成文), CHEN Yuting (陈禹廷), ZHANG Yong* (张勇) 2019, 24 (1):  12-18.  doi: 10.1007/s12204-018-2007-9 Abstract ( 414 )   PDF (1748KB) ( 120 )   Ternary polyamide (tPA) copolymer is susceptible to degradation when it is irradiated by electron beam (e-beam), and effective methods to avoid degradation and increase gel content are highly desirable for crosslinking. Carboxylated multiwall carbon nanotube (MWCNT) is modified by hydroxyethyl acrylate (HEA) in this paper and used as a co-agent for the e-beam irradiation crosslinking of tPA copolymer. HEA modified MWCNT can function as an effective co-agent for the e-beam irradiation crosslinking of tPA copolymer to increase the gel content and improve the mechanical properties of tPA copolymer. Under an irradiation of 160 kGy, addition of 2 parts per hundred (phr) HEA modified MWCNT into tPA copolymer can increase the gel content of tPA copolymer from about 20% to 40% (mass ratio) and increase the tensile strength from 45 to 59MPa. The irradiation also affects the glass transition temperature of tPA copolymer by increasing the gel content. The results show that HEA modified MWCNT can act as a nucleating agent to increase the crystallization temperature, melting temperature and crystallinity of tPA copolymer. References | Related Articles | Metrics

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Maneuverability Simulations for Twin-Waterjet Propulsion Vessel XU Zijing (徐梓京), LIN Hui (林辉), DU Dongmei (杜冬梅), WANG Luyi (王路逸), CHEN Jianping (陈建平), SONG Chenwei (宋晨维), YUAN Jingqi*(袁景淇) 2019, 24 (1):  19-23.  doi: 10.1007/s12204-019-2036-z Abstract ( 537 )   PDF (260KB) ( 132 )   Maneuverability is one of the most important sailing performances of vessels. In this article, a motion control model with three degrees of freedom (DoFs) for twin-waterjet propulsion vessel is proposed. The model is developed on the basis of maneuvering model group (MMG) maneuverability equations. A simulation environment is constructed on the Matlab Simulink platform. Standard turning tests and zig-zag tests are simulated by solving the motion control model, and the corresponding maneuverability parameters are calculated. Simulation results demonstrate that the maneuverability parameters are in accordance with the vessel maneuverability standard. The approach may be applied to the rapid prediction of vessel maneuverability. References | Related Articles | Metrics

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Simple Approach on Intermixing Solar and Wind Energy and Minimizing Their Intermittent Effect KARNI Awais, LUO Liwen *(罗利文), MUMTAZ Muhammad Adnan, ZAKI Atta ul Munim 2019, 24 (1):  24-30.  doi: 10.1007/s12204-019-2037-y Abstract ( 477 )   PDF (314KB) ( 131 )   Renewable energy resources especially wind and solar energy are emerging as the modern power sources to electrify remote areas. The main reason behind their emergence is due to their environment-friendly behavior, unlimited availability and short period for replenishment over nonrenewable energy resources. Renewable energy resources are much better than nonrenewable energy resources, but the intermittency in renewable energy resources degrades the system performance. In order to overcome the intermittency, multiple hybrid system techniques were proposed in literature that can achieve suitable results but have disadvantages of complicated control structures and high implementation cost. Considering aforementioned shortcomings, a simple balancing approach is proposed to intermix solar and wind energy together so as to utilize the available energy from both sources at a given time. It is very common that solar farms are the dominating source of energy in daytime and summer, while wind farms are the dominating source of energy at night and in winter. The proposed approach delivers maximum possible power to the load by combining dominating and non-dominating resources all the time, hence mitigating the intermittency of individual resources. Compared with other approaches, the proposed approach offers key benefits with redundancy, simple design and low cost, which can be analyzed from simulation results. References | Related Articles | Metrics

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Fast Confidentiality-Preserving Authentication for Vehicular Ad Hoc Networks MIRZAEE Siavash, JIANG Letian *(蒋乐天) 2019, 24 (1):  31-40.  doi: 10.1007/s12204-019-2038-x Abstract ( 355 )   PDF (368KB) ( 121 )   This paper studies the existing problems of message authentication protocols in vehicular ad hoc networks (VANETs) due to their significance in the future of commuting and transportation. Our contribution has been devoted to implementing a new protocol for VANETs so that inherent security problems in past works are resolved. Exclusive security measures have been considered for the system which protects the users against threat of any attack. The new protocol shows a great hardness guaranteed by certificate based 80 bit security which assures messages to remain confidential in any time. Also, new unprecedented features like V2X which improves system performance effectively have been instantiated. The simulation results indicate that message signature generation and verification both take place in much less time than present comparable rival protocols. References | Related Articles | Metrics

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Hybrid Optimization Algorithm Based on Wolf Pack Search and Local Search for Solving Traveling Salesman Problem DONG Ruyi (董如意), WANG Shengsheng *(王生生), WANG Guangyao (王光耀), WANG Xinying (王新颖) 2019, 24 (1):  41-47.  doi: 10.1007/s12204-019-2039-9 Abstract ( 459 )   PDF (227KB) ( 124 )   Traveling salesman problem (TSP) is one of the typical NP-hard problems, and it has been used in many engineering applications. However, the previous swarm intelligence (SI) based algorithms for TSP cannot coordinate with the exploration and exploitation abilities and are easily trapped into local optimum. In order to deal with this situation, a new hybrid optimization algorithm based on wolf pack search and local search (WPS-LS) is proposed for TSP. The new method firstly simulates the predatory process of wolf pack from the broad field to a specific place so that it allows for a search through all possible solution spaces and prevents wolf individuals from getting trapped into local optimum. Then, local search operation is used in the algorithm to improve the speed of solving and the accuracy of solution. The test of benchmarks selected from TSPLIB shows that the results obtained by this algorithm are better and closer to the theoretical optimal values with better robustness than those obtained by other methods. References | Related Articles | Metrics

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UAV's Coverage Search Planning Algorithm Based on Action Combinations CHEN Zirong *(陈仔荣), LU Yafei (鲁亚飞), HOU Zhongxi (侯中喜), WANG Junwei (王俊伟) 2019, 24 (1):  48-57.  doi: 10.1007/s12204-018-2010-1 Abstract ( 509 )   PDF (3482KB) ( 139 )   The autonomous route planning in coverage search is an important subject of unmanned aerial vehicle (UAV) mission planning. Pre-planning is simple and feasible for the coverage search mission of single UAV in regular areas. As to the dynamic mission in complicated environment of multi-UAV, the route planning will encounter the difficulties of reasonable task distribution and the real-time environment changes which include the changes of the mission area, the detection of threat area, the interference of communication and so on. At this point, making the UAV to do real-time autonomous planning is necessary. However, it is hard to fulfil requirements of real-time, autonomous and efficient at the same time. According to a scalable knowledge base, this paper proposes a coverage search algorithm which is based on the mapping between the basic behavior combination and surroundings. A UAV’s coverage search simulation model with random shapes is built with a discrete map to update the environment and the changes of the mission on time. Comparison of the simulation analysis and the dynamic programming shows that the method has amazing expandability and can change the search strategy feasibly. It is efficient, and the ratio of coverage redundancy can be decreased to 1.21. It also has the potentiality in real-time calculation, and the computing time can be shortened to about 2 s. References | Related Articles | Metrics

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Dynamic Simulation Analysis of Humanoid Robot Walking System Based on ADAMS ZHANG Bangcheng *(张邦成), SHAO Chen (邵晨), LI Yongsheng (李永生), TAN Haidong (谭海东), JIANG Dawei (姜大伟) 2019, 24 (1):  58-63.  doi: 10.1007/s12204-019-2040-3 Abstract ( 408 )   PDF (669KB) ( 131 )   Humanoid robots are a hot topic in the field of robotics research. The walking system is the critical part of the humanoid robot, and the dynamic simulation of the walking system is of great importance. In this paper, the stability of the walking system and the rationality of its structural design are considered in the study of dynamics for a humanoid robot. The dynamic model of humanoid robot walking system is established by using the Lagrange dynamics method. Additionally, the three-dimensional model of CATIA is imported into ADAMS. The humanoid robot walking system is added with the movement of the deputy and the driving force in the ADAMS. The torque and angular velocity of the ankle joint and hip joint are analyzed in the process of knee bends. The simulation results show that the overall performance of the humanoid robot walking system is favorable and has a smooth movement, and the specified actions can be completed, which proves the rationality of the humanoid robot walking system design. References | Related Articles | Metrics

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Semi-Active Predictive Control of Isolated Bridge Based on Magnetorheological Elastomer Bearing LI Rui (李锐), ZHOU Mengjiao (周梦娇), WU Mengjuan (吴孟娟), TANG Xiaoming *(唐晓铭) 2019, 24 (1):  64-70.  doi: 10.1007/s12204-018-2009-7 Abstract ( 397 )   PDF (510KB) ( 125 )   Time-delay of magnetorheological elastomer bearing (MRB) can bring structural response menace to bridges. This paper investigates a bridge pier-bearing semi-active-coupling control method based on model predictive control (MPC). The presented strategy takes the structure prediction model to predict the state responses of the controlled plant in a period of future time. Then, the control law can be determined by solving a finite horizon optimization problem. The peak shearing force of pier top, the displacement and the acceleration of beam are chosen as control goals, and the vibration isolation rate is applied to characterize the vibration isolation effect. It is noted that MPC method naturally takes the time-delay and uncertain interference into consideration, and significantly improves the control performance of the system. Finally, the numerical example is described and the seismic response of isolated bridge based on MRB is analyzed. The simulation results show that predictive control can be used to control the time-delay of bridge system in different degrees. The best control performance is at 0.4 s. Even if the time-delay reaches 2 s, it is still good. Therefore, the control method significantly reduces the adverse effects of time-delay on the system, and has a good vibration isolation performance. References | Related Articles | Metrics

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A Community Detection Algorithm Based on Markov Random Walks Ants in Complex Network MA Jian *(马健), FAN Jianping (樊建平), LIU Feng (刘峰), LI Honghui (李红辉) 2019, 24 (1):  71-77.  doi: 10.1007/s12204-019-2041-2 Abstract ( 353 )   PDF (636KB) ( 113 )   Complex networks display community structures. Nodes within groups are densely connected but among groups are sparsely connected. In this paper, an algorithm is presented for community detection named Markov Random Walks Ants (MRWA). The algorithm is inspired by Markov random walks model theory, and the probability of ants located in any node within a cluster will be greater than that located outside the cluster. Through the random walks, the network structure is revealed. The algorithm is a stochastic method which uses the information collected during the traverses of the ants in the network. The algorithm is validated on different datasets including computer-generated networks and real-world networks. The outcome shows the algorithm performs moderately quickly when providing an acceptable time complexity and its result appears good in practice. References | Related Articles | Metrics

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LQR-GA Controller for Articulated Dump Truck Path Tracking System MENG Yu *(孟宇), GAN Xin (甘鑫), WANG Yu (汪钰), GU Qing (顾青) 2019, 24 (1):  78-85.  doi: 10.1007/s12204-018-2012-z Abstract ( 467 )   PDF (1186KB) ( 114 )   This paper designs a novel controller to improve the path-tracking performance of articulated dump truck (ADT). By combining linear quadratic regulator (LQR) with genetic algorithm (GA), the designed controller is used to control linear and angular velocities on the midpoint of the front frame. The novel controller based on the error dynamics model is eventually realized to track the path high-precisely with constant speed. The results of simulation and experiment show that the LQR-GA controller has a better tracking performance than the existing methods under a low speed of 3m/s. In this paper, kinematics model and simulation control models based on co-simulation of ADAMS and Matlab/Simulink are established to verify the proposed strategy. In addition, a real vehicle experiment is designed to further more correctness of the conclusion. With the proposed controller and considering the steering model in the simulation, the control performance is improved and matches the actual situation better. The research results contribute to the development of automation of ADT. References | Related Articles | Metrics

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Steam Pressure Control of 1 000MW Ultra-Supercritical Coal-Fired Power Unit Based on Multi-Model Predictive Control WANG Guoliang *(王国良), DING Baocang (丁宝苍), YAN Weiwu (阎威武) 2019, 24 (1):  86-93.  doi: 10.1007/s12204-018-2015-9 Abstract ( 358 )   PDF (374KB) ( 105 )   Ultra-supercritical (USC) coal-fired unit is more and more popular in these years for its advantages. But the control of USC unit is a difficult issue for its characteristic of nonlinearity, large dead time and coupling among inputs and outputs. In this paper, model predictive control (MPC) method based on multi-model and double layered optimization is introduced for coordinated control of USC unit running in sliding pressure mode and fixed pressure mode. Three inputs (i.e. valve opening, coal flow and feedwater flow) are employed to control three outputs (i.e. output power, main steam temperature and main steam pressure). The step responses for the dynamic matrix control (DMC) are constructed using the three inputs by the three outputs under both pressure control mode. Piecewise models are built at selected operation points. In simulation, the output power follows load demand quickly and main steam temperature can be controlled around the setpoint closely in load tracking control. The simulation results show the effectiveness of the proposed methods. References | Related Articles | Metrics

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Dynamic Mechanical Properties of EPS Concrete Under Impact Loading HU Jun *(胡俊), REN Jianwei (任建伟), WU Deyi (吴德义) 2019, 24 (1):  94-100.  doi: 10.1007/s12204-019-2042-1 Abstract ( 376 )   PDF (4722KB) ( 109 )   The finite element method (FEM) models of expanded polystyrene (EPS) concrete were established to study the relationships among dynamic damage, energy absorption and efficiency of buffering materials with varied flexible aggregate contents and impact speeds based on the existing split Hopkinson pressure bar (SHPB) experiments. Applied material indexes including damage degrees, crack rates and energy absorption capacities, and the dynamic responses of EPS concrete under impact loading were investigated. The results show that the failure types of these materials evolve from quasi-brittle destruction to flow-plastic destruction, the damage degree of EPS concrete increases with the enhancement of flexible aggregate content, and the peak of crack rate exists around the extreme point of shock velocities. The energy-absorption efficiency of EPS concrete increases nonlinearly when the EPS beads increase and the shock speed enhances, respectively. References | Related Articles | Metrics

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A Novel RRAM Based PUF for Anti-Machine Learning Attack and High Reliability DAI Lan *(戴澜), YAN Qiangqiang (闫强强), YI Shengyu (易盛禹), LIU Wenkai (刘文楷), QIAN He (钱鹤) 2019, 24 (1):  101-106.  doi: 10.1007/s12204-019-2043-0 Abstract ( 428 )   PDF (2475KB) ( 113 )   Due to the unique response mechanism, physical unclonable function (PUF) has been extensively studied as a hardware security primitive. And compared to other PUFs, the resistive random access memory (RRAM) based PUF has more flexibility with the change of conductive filaments. In this work, we propose an exclusive or (XOR) strong PUF based on the 1Kbit 1-transistor-1-resistor (1T1R) arrays, and unlike the traditional RRAM based strong PUF, the XOR PUF has a stronger anti-machine learning attack ability in our experiments. The reliability of XOR RRAM PUF is determined by the read instability, thermal dependence of RRAM resistance, and aging. We used a split current distribution scheme to make the reliability of XOR PUF significantly improved. After baking for 50 h at a high temperature of 150?C, the intra-chip Hamming distance (Intra-HD) only increased from 0 to 4.5%. The inter-chip Hamming distance (Inter-HD) and uniformity are close to 50% (ideally). And it is proven through the NIST test that XOR PUF has a high uniqueness. References | Related Articles | Metrics

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Delayed Detached Eddy Simulation of Subcritical Flow past Generic Side Mirror CHEN Xin (陈鑫), LI Ming *(李铭) 2019, 24 (1):  107-112.  doi: 10.1007/s12204-019-2044-z Abstract ( 417 )   PDF (2134KB) ( 106 )   In the present study, the subcritical flow past a generic side mirror on a base plane is investigated at the Reynolds number of 5.2×105 using delayed detached eddy simulation (DDES) turbulence model. Asides from the capability of capturing main features of the large recirculation vortex in the wake of the side mirror and the front horseshoe vortex, the accuracy of DDES estimation of recirculation length is significantly increased by over 20%, compared to the detached eddy simulation (DES) estimation using the same grid. And DDES prediction of pressure coefficient at the trailing edge of the mirror is in good agreement with the experiments, which is more accurate than both DES and large eddy simulation (LES) results. The results verify the capacity of DDES turbulence model to solve the turbulent flow around the side mirror. This is a key foundation for possible future study of full simulation of external flow field of vehicle. References | Related Articles | Metrics

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Numerical Research of Flow past a Circular Cylinder with Splitter Plate at a Subcritical Reynolds Number Region AN Xinyu *(安新宇), SONG Baowei (宋保维), TIAN Wenlong (田文龙), MA Congcong (马聪聪) 2019, 24 (1):  113-121.  doi: 10.1007/s12204-019-2045-y Abstract ( 415 )   PDF (5846KB) ( 125 )   Numerical research of flow past a circular cylinder with a splitter at the subcritical Reynolds number region of 5 × 104—9 × 104 was researched based on Computational Fluid Dynamics (CFD) through solving twodimensional incompressible unsteady Reynolds-averaged Navier-Stokes (URANS) equations with the shear stress transport (SST) k-ω turbulence model. Three different grid resolutions were employed in the verification and validation study of the adopted turbulence model. Various fluid characteristics such as Strouhal number, lift coefficient of the cylinder and the splitter with respect to various splitter lengths and different Reynolds numbers were investigated. It was revealed that the lift coefficient ratio of the splitter over the cylinder remains near 1.6 when the splitter length is 1.5—4 times the cylinder’s diameter. Vortex shedding is strongly inhibited when the splitter length is greater than a critical value of around four times the cylinder’s diameter. The phase difference of the lift coefficient on the upper and lower surface of the splitter varies between ?30? and 30?. The maximal lift coefficients are reached when the splitter length is about 2 times the cylinder’s diameter. Besides, the splitter length has little influence on the separation angle around the cylinder. References | Related Articles | Metrics

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Vehicle Ego-Localization Based on Streetscape Image Database Under Blind Area of Global Positioning System ZHOU Jingmei *(周经美), ZHAO Xiangmo (赵祥模), CHENG Xin (程鑫), XU Zhigang (徐志刚), ZHAO Huaixin (赵怀鑫) 2019, 24 (1):  122-129.  doi: 10.1007/s12204-018-2008-8 Abstract ( 588 )   PDF (1845KB) ( 142 )   Vehicle positioning is critical for inter-vehicle communication, navigation, vehicle monitoring and tracking. They are regarded as the core technology ensuring safety in everyday-driving. This paper proposes an enhanced vehicle ego-localization method based on streetscape image database. It is most useful in the global positioning system (GPS) blind area. Firstly, a database is built by collecting streetscape images, extracting dominant color feature and detecting speeded up robust feature (SURF) points. Secondly, an image that the vehicle shoots at one point is analyzed to find a matching image in the database by dynamic programming (DP) matching. According to the image similarity, several images with higher probabilities are selected to realize coarse positioning. Finally, different weights are set to the coordinates of the shooting location with the maximum similarity and its 8 neighborhoods according to the number of matching points, and then interpolating calculation is applied to complete accurate positioning. Experimental results show that the accuracy of this study is less than 1.5m and its running time is about 3.6 s. These are basically in line with the practical need. The described system has an advantage of low cost, high reliability and strong resistance to signal interference, so it has a better practical value as compared with visual odometry (VO) and radio frequency identification (RFID) based approach for vehicle positioning in the case of GPS not working. References | Related Articles | Metrics

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Particle Filter and Its Application in the Integrated Train Speed Measurement ZHANG Liang (张梁), BAO Qilian *(鲍其莲), CUI Ke (崔科), JIANG Yaodong (蒋耀东), XU Haigui (徐海贵), DU Yuding (杜雨丁) 2019, 24 (1):  130-136.  doi: 10.1007/s12204-019-2046-x Abstract ( 520 )   PDF (304KB) ( 120 )   Particle filter (PF) can solve the problem of state estimation under strong non-linear non-Gaussian noise condition with respect to traditional Kalman filter (KF) and those improved KFs such as extended KF (EKF) and unscented KF (UKF). However, problems such as particle depletion and particle degradation affect the performance of PF. Optimizing the particle set to high likelihood region with intelligent optimization algorithm results in a more reasonable distribution of the sampling particles and more accurate state estimation. In this paper, a novel bird swarm algorithm based PF (BSAPF) is presented. Firstly, different behavior models are established by emulating the predation, flight, vigilance and follower behavior of the birds. Then, the observation information is introduced into the optimization process of the proposal distribution with the design of fitness function. In order to prevent particles from getting premature (being stuck into local optimum) and increase the diversity of particles, L′evy flight is designed to increase the randomness of particle’s movement. Finally, the proposed algorithm is applied to estimate the speed of the train under the condition that the measurement noise of the wheel sensor is non-Gaussian distribution. Simulation study and experimental results both show that BSAPF is more accurate and has more effective particle number as compared with PF and UKF, demonstrating the promising performance of the method. References | Related Articles | Metrics