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  • 1
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    A Novel Fault Diagnosis Method for Diesel Engine Based on MVMD and Band Energy (2020)
    Hindawi
    Details
    Publication Date: 2020-07-06
    Description: Vibration signal, as an important means for diesel engine condition detection and fault diagnosis, has attracted attention for many years. In traditional vibration signal analysis, most processing methods are for single-channel data. However, single-channel vibration signal cannot reflect the operating information of the diesel engine comprehensively because diesel engine vibration is coupled by multiple source signals. This paper proposes the MVMD band energy method for fault diagnosis by four channels of vibration signals. First, the original multivariate signals are decomposed adaptively by MVMD, which obtains a series of components with modal alignment. Then, the band energy values of each measuring point are calculated as the fault characteristics. Finally, SVM is used to realize the diagnosis and identification of diesel engine misfire. The working conditions have a great influence on the vibration signal of the cylinder. In order to obtain the best diagnostic working conditions, six working conditions are set for testing. The result shows that the fault identification rate is highest under the 1500 rpm and 50% load working condition. The fault recognition rate of this method reaches more than 99%, which is superior to the other four common methods.
    Print ISSN: 1070-9622
    Electronic ISSN: 1875-9203
    Topics: Mathematics
    Published by Hindawi
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  • 2
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    Theoretical Insights into Three Types of Oxidized Starch-Based Adhesives: Chemical Stability, Water Resistance, and Shearing Viscosity from a Molecular Viewpoint (2016)
    Hindawi
    Details
    Publication Date: 2016-08-05
    Description: To better understand the origin and difference associated with chemical stability, water resistance, and shearing viscosity of three types of different oxidized modified starch-based adhesives, a detailed theoretical investigation from a molecular viewpoint has been performed using the AM1 semiempirical level and the DFT-B3LYP level, respectively. As a result, our findings suggest that, by Mulliken population analysis (MPA), frontier orbital analysis, and electrostatic potential (EP) analysis based on B3LYP/6-31G calculations, the chemical stability, water resistance, and shearing viscosity of the oxidized modified starch-based adhesives are uniformly improved and corresponding difference for each property presents an identical order: the oxidized grafted cross-linked starch-based adhesive 〉 the oxidized grafted starch-based adhesive 〉 the oxidized starch-based adhesive, which is well consistent with experimental results.
    Print ISSN: 2090-9063
    Topics: Chemistry and Pharmacology
    Published by Hindawi
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  • 3
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    Matching Cost Filtering for Dense Stereo Correspondence (2013)
    Hindawi
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    Publication Date: 2013-10-01
    Description: Dense stereo correspondence enabling reconstruction of depth information in a scene is of great importance in the field of computer vision. Recently, some local solutions based on matching cost filtering with an edge-preserving filter have been proved to be capable of achieving more accuracy than global approaches. Unfortunately, the computational complexity of these algorithms is quadratically related to the window size used to aggregate the matching costs. The recent trend has been to pursue higher accuracy with greater efficiency in execution. Therefore, this paper proposes a new cost-aggregation module to compute the matching responses for all the image pixels at a set of sampling points generated by a hierarchical clustering algorithm. The complexity of this implementation is linear both in the number of image pixels and the number of clusters. Experimental results demonstrate that the proposed algorithm outperforms state-of-the-art local methods in terms of both accuracy and speed. Moreover, performance tests indicate that parameters such as the height of the hierarchical binary tree and the spatial and range standard deviations have a significant influence on time consumption and the accuracy of disparity maps.
    Print ISSN: 1024-123X
    Electronic ISSN: 1563-5147
    Topics: Mathematics , Technology
    Published by Hindawi
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  • 4
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    A New Feature Points Reconstruction Method in Spacecraft Vision Navigation (2015)
    Hindawi
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    Publication Date: 2015-03-31
    Description: The important applications of monocular vision navigation in aerospace are spacecraft ground calibration tests and spacecraft relative navigation. Regardless of the attitude calibration for ground turntable or the relative navigation between two spacecraft, it usually requires four noncollinear feature points to achieve attitude estimation. In this paper, a vision navigation system based on the least feature points is designed to deal with fault or unidentifiable feature points. An iterative algorithm based on the feature point reconstruction is proposed for the system. Simulation results show that the attitude calculation of the designed vision navigation system could converge quickly, which improves the robustness of the vision navigation of spacecraft.
    Print ISSN: 1024-123X
    Electronic ISSN: 1563-5147
    Topics: Mathematics , Technology
    Published by Hindawi
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  • 5
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    Novel UHF RFID Near-Field Reader Antenna with Uniform Vertical Electric Field Distribution (2020)
    Hindawi
    Details
    Publication Date: 2020-08-24
    Description: This paper presents two novel UHF RFID near-field reader antennas with uniform vertical electric field distribution. The two antennas have the following common characteristics. First, the radiating parts of the two antennas are simulated and fabricated by the microstrip lines and work using the leakage wave principle of microstrip lines. Second, the end of microstrip lines match the load to form a traveling wave mode of operation, so the two antennas have broadband characteristics. Third, both antennas are fed in a coaxial manner at the center of the antenna. The simulation and measurement results can show that the proposed three-branch antenna and four-branch antenna achieve good impedance matching in the range of 883–960 MHz and 870–960 MHz, respectively, and achieve uniform distribution of the vertical electric field component in a certain area. The reading areas of the three-branch antenna and the four-branch antenna are 70 mm × 70 mm × 90 mm and 100 mm × 100 mm × 120 mm (length × width × height), respectively. Due to the introduction of the ground plate, the antenna gain is low, which meets the design requirements of near-field antennas.
    Print ISSN: 1687-5869
    Electronic ISSN: 1687-5877
    Topics: Electrical Engineering, Measurement and Control Technology
    Published by Hindawi
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  • 6
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    Approximate Kelvin-Voigt Fluid Driven by an External Force Depending on Velocity with Distributed Delay (2015)
    Hindawi
    Details
    Publication Date: 2015-10-12
    Description: We consider the approximate 3D Kelvin-Voigt fluid driven by an external force depending on velocity with distributed delay. We investigate the long time behavior of solutions to Navier-Stokes-Voigt equation with a distributed delay external force depending on the velocity of fluid on a bounded domain. By a prior estimate and a contractive function, we give a sufficient condition for the existence of pullback attractor of NSV equation.
    Print ISSN: 1026-0226
    Electronic ISSN: 1607-887X
    Topics: Mathematics
    Published by Hindawi
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  • 7
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    Triaxial Accelerometer Error Coefficients Identification with a Novel Artificial Fish Swarm Algorithm (2015)
    Hindawi
    Details
    Publication Date: 2015-06-03
    Description: Artificial fish swarm algorithm (AFSA) is one of the state-of-the-art swarm intelligence techniques, which is widely utilized for optimization purposes. Triaxial accelerometer error coefficients are relatively unstable with the environmental disturbances and aging of the instrument. Therefore, identifying triaxial accelerometer error coefficients accurately and being with lower costs are of great importance to improve the overall performance of triaxial accelerometer-based strapdown inertial navigation system (SINS). In this study, a novel artificial fish swarm algorithm (NAFSA) that eliminated the demerits (lack of using artificial fishes’ previous experiences, lack of existing balance between exploration and exploitation, and high computational cost) of AFSA is introduced at first. In NAFSA, functional behaviors and overall procedure of AFSA have been improved with some parameters variations. Second, a hybrid accelerometer error coefficients identification algorithm has been proposed based on NAFSA and Monte Carlo simulation (MCS) approaches. This combination leads to maximum utilization of the involved approaches for triaxial accelerometer error coefficients identification. Furthermore, the NAFSA-identified coefficients are testified with 24-position verification experiment and triaxial accelerometer-based SINS navigation experiment. The priorities of MCS-NAFSA are compared with that of conventional calibration method and optimal AFSA. Finally, both experiments results demonstrate high efficiency of MCS-NAFSA on triaxial accelerometer error coefficients identification.
    Print ISSN: 1687-725X
    Electronic ISSN: 1687-7268
    Topics: Electrical Engineering, Measurement and Control Technology
    Published by Hindawi
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  • 8
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    Development of a Multitype Wireless Sensor Network for the Large-Scale Structure of the National Stadium in China (2013)
    Hindawi
    Details
    Publication Date: 2013-12-09
    Description: A multitype wireless sensor network (WSN) for structural health monitoring is developed for the National Stadium in China (generally known as “Bird’s Nest”). The stadium is a super large-scale building built for the 2008 Beijing Olympic Games and can house more than 90,000 occupants. The structure is very rigid and weighs more than 40,000 tons in total. Considering the structural features and on-site environment, the system takes multitype sensors as measurement components including stress, displacement, acceleration, wind, and temperature. The monitoring module design consists of four functions: sensing, processing, wireless communication, and energy management. The communication between each sensor node is realized by using an adjustable and artificial-control chain-type network. A total of 290 sensors were installed on the structure, and the data collection work has been carried out for more than one year. This paper mainly focuses on the system development and project application, while the data analysis work is briefly discussed as well. It can be concluded that the customized WSN is robust and durable, which well satisfies the requirement of plenty multitype sensors working in a large-area distribution. The data analysis results reveal that the super large-scale structure is very sensitive to the temperature effect.
    Print ISSN: 1550-1329
    Electronic ISSN: 1550-1477
    Topics: Electrical Engineering, Measurement and Control Technology
    Published by Hindawi
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  • 9
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    Stochastic Viscoelastic Wave Equations with Nonlinear Damping and Source Terms (2014)
    Hindawi
    Details
    Publication Date: 2014-03-28
    Description: The goal of this paper is to study an initial boundary value problem of stochastic viscoelastic wave equation with nonlinear damping and source terms. Under certain conditions on the initial data: the relaxation function, the indices of nonlinear damping, and source terms and the random force, we prove the local existence and uniqueness of solution by the Galerkin approximation method. Then, considering the relationship between the indices of nonlinear damping and nonlinear source, we give the necessary conditions of global existence and explosion in finite time in some sense of solutions, respectively.
    Print ISSN: 1110-757X
    Electronic ISSN: 1687-0042
    Topics: Mathematics
    Published by Hindawi
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  • 10
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    Collaborative Deformation Design Using Control Integrated Analysis Methods for Hypersonic Waverider (2015)
    Hindawi
    Details
    Publication Date: 2015-03-31
    Description: Hypersonic waveriders have a large flight envelope, leading to the difficulty in keeping overall flight stability for a fixed geometry. Accordingly, hypersonic waveriders can be considered to design as a morphing vehicle such that the flight range is expanded for waveriding stability. To this end, this paper investigates the collaborative deformation design using control integrated analysis methods for the hypersonic waverider. Firstly, a parametric model is applied to combine the shape deformation with the geometrical properties. Secondly, the morphing process with regard to the change in a single geometric parameter and the static and dynamic characteristics affected by this deformation are analyzed. Afterwards, the collaborative relations are discussed for the changes in the lower forebody angle and elevon area. Furthermore, a flight control law is designed to guarantee flight stability while implementing the collaborative deformation, and the morphing results are evaluated based on the control-oriented idea. Finally, a simulation example is used to verify the effectiveness of the proposed methods for the hypersonic waverider.
    Print ISSN: 1687-5966
    Electronic ISSN: 1687-5974
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Published by Hindawi
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