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  • 1
    Online Resource
    Online Resource
    Analytical expression and simulation study of quantum radar scattering characteristics of triangular pyramid
    World Scientific Pub Co Pte Ltd ; 2022
    In:  Modern Physics Letters B Vol. 36, No. 30n31 ( 2022-11-10)
    Details
    In: Modern Physics Letters B, World Scientific Pub Co Pte Ltd, Vol. 36, No. 30n31 ( 2022-11-10)
    Abstract: Due to the constant development of quantum radar technology, it has become increasingly important to study the scattering properties of quantum radars of typical targets. In this study, the analytical expression of the triangular pyramid is determined by solving the Fourier transform of each plane of the triangular pyramid, and their quantum radar scattering cross-section, to propose a solution to the equivalent transformation of the elevation angle and azimuth angle of the inclined plane. Besides, based on the simulation result of the triangular pyramid QRCS, it can be seen that the results obtained by using this calculation are consistent with the numerical solutions, and that the calculation time is significantly reduced.
    Type of Medium: Online Resource
    ISSN: 0217-9849 , 1793-6640
    URL: Article
    DOI: 10.1142/S0217984922501755
    RVK:
    UA 5534.B
    Language: English
    Publisher: World Scientific Pub Co Pte Ltd
    Publication Date: 2022
    detail.hit.zdb_id: 896450-6
    detail.hit.zdb_id: 2038670-9
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  • 2
    Online Resource
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    A Comprehensive Optimization Design Method of Aerodynamic, Acoustic, and Stealth of Helicopter Rotor Blades Based on Genetic Algorithm
    Wiley ; 2019
    In:  Mathematical Problems in Engineering Vol. 2019 ( 2019-04-09), p. 1-12
    Details
    In: Mathematical Problems in Engineering, Wiley, Vol. 2019 ( 2019-04-09), p. 1-12
    Abstract: In this paper, a comprehensive optimization approach is presented to analyze the aerodynamic, acoustic, and stealth characteristics of helicopter rotor blades in hover flight based on the genetic algorithm (GA). The aerodynamic characteristics are simulated by the blade element momentum theory. And the acoustics are computed by the Farassat theory. The stealth performances are calculated through the combination of physical optics (PO) and equivalent currents (MEC). Furthermore, an advanced geometry representation algorithm which applies the class function/shape function transformation (CST) is introduced to generate the airfoil coordinates. This method is utilized to discuss the airfoil shape in terms of server design variables. The aerodynamic, acoustic, and stealth integrated design aims to achieve the minimum radar cross section (RCS) under the constraint of aerodynamic and acoustic requirement through the adjustment of airfoil shape design variables. Two types of rotor are used to illustrate the optimization method. The results obtained in this work show that the proposed technique is effective and acceptable.
    Type of Medium: Online Resource
    ISSN: 1024-123X , 1563-5147
    URL: Article
    DOI: 10.1155/2019/4153715
    Language: English
    Publisher: Wiley
    Publication Date: 2019
    detail.hit.zdb_id: 2014442-8
    detail.hit.zdb_id: 1385243-7
    SSG: 11
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  • 3
    Online Resource
    Online Resource
    Legendre wavelets method for the numerical solution of fractional integro-differential equations with weakly singular kernel
    Elsevier BV ; 2016
    In:  Applied Mathematical Modelling Vol. 40, No. 4 ( 2016-02), p. 3422-3437
    Details
    In: Applied Mathematical Modelling, Elsevier BV, Vol. 40, No. 4 ( 2016-02), p. 3422-3437
    Type of Medium: Online Resource
    ISSN: 0307-904X
    URL: Article
    DOI: 10.1016/j.apm.2015.10.009
    Language: English
    Publisher: Elsevier BV
    Publication Date: 2016
    detail.hit.zdb_id: 197129-3
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  • 4
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    Active cancellation analysis based on the radar detection probability
    Elsevier BV ; 2015
    In:  Aerospace Science and Technology Vol. 46 ( 2015-10), p. 273-281
    Details
    In: Aerospace Science and Technology, Elsevier BV, Vol. 46 ( 2015-10), p. 273-281
    Type of Medium: Online Resource
    ISSN: 1270-9638
    URL: Article
    DOI: 10.1016/j.ast.2015.07.018
    Language: English
    Publisher: Elsevier BV
    Publication Date: 2015
    detail.hit.zdb_id: 1378482-1
    SSG: 16,12
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  • 5
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    Online Resource
    Computation of Aerodynamic Noise Radiated from Ducted Tail Rotor Using Boundary Element Method
    Wiley ; 2017
    In:  Mathematical Problems in Engineering Vol. 2017 ( 2017), p. 1-13
    Details
    In: Mathematical Problems in Engineering, Wiley, Vol. 2017 ( 2017), p. 1-13
    Abstract: A detailed aerodynamic performance of a ducted tail rotor in hover has been numerically studied using CFD technique. The general governing equations of turbulent flow around ducted tail rotor are given and directly solved by using finite volume discretization and Runge-Kutta time integration. The calculations of the lift characteristics of the ducted tail rotor can be obtained. In order to predict the aerodynamic noise, a hybrid method combining computational aeroacoustic with boundary element method (BEM) has been proposed. The computational steps include the following: firstly, the unsteady flow around rotor is calculated using the CFD method to get the noise source information; secondly, the radiate sound pressure is calculated using the acoustic analogy Curle equation in the frequency domain; lastly, the scattering effect of the duct wall on the propagation of the sound wave is presented using an acoustic thin-body BEM. The aerodynamic results and the calculated sound pressure levels are compared with the known technique for validation. The sound pressure directivity and scattering effect are shown to demonstrate the validity and applicability of the method.
    Type of Medium: Online Resource
    ISSN: 1024-123X , 1563-5147
    URL: Article
    DOI: 10.1155/2017/5726253
    Language: English
    Publisher: Wiley
    Publication Date: 2017
    detail.hit.zdb_id: 2014442-8
    detail.hit.zdb_id: 1385243-7
    SSG: 11
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  • 6
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    Noise Phase Characteristics and the Noise Cancellation of Twin-Coaxial Rotor Based on Phase Modulation Method
    Springer Science and Business Media LLC ; 2022
    In:  International Journal of Aeronautical and Space Sciences Vol. 23, No. 5 ( 2022-11), p. 834-847
    Details
    In: International Journal of Aeronautical and Space Sciences, Springer Science and Business Media LLC, Vol. 23, No. 5 ( 2022-11), p. 834-847
    Type of Medium: Online Resource
    ISSN: 2093-274X , 2093-2480
    URL: Article
    DOI: 10.1007/s42405-022-00475-2
    Language: English
    Publisher: Springer Science and Business Media LLC
    Publication Date: 2022
    detail.hit.zdb_id: 2922594-2
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  • 7
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    Research on Crude Oil Demulsification Using the Combined Method of Ultrasound and Chemical Demulsifier
    Wiley ; 2017
    In:  Journal of Chemistry Vol. 2017 ( 2017), p. 1-7
    Details
    In: Journal of Chemistry, Wiley, Vol. 2017 ( 2017), p. 1-7
    Abstract: In this paper, experiments of crude oil demulsification using ultrasound, chemical demulsifier, and the combined method of ultrasound and chemical demulsifier, respectively, at different temperatures (40°C, 60°C, and 70°C) are carried out. The photos of water droplet distribution in crude oil, taken with microscopic imaging system, before and after demulsification using the above methods at 70°C are given. Research results show that the combined method of ultrasound and chemical demulsifier has the best demulsification effect, followed by chemical demulsifier. Ultrasound without using chemical demulsifier has the least demulsification effect. Furthermore, the impact of ultrasonic power, treatment time, and temperature on crude oil demulsification using the combined method of ultrasound and chemical demulsifier is studied. Results indicate that the final dehydration rate increases with the increase of temperatures and ultrasonic power and almost does not change with the increase of ultrasonic treatment time. These important conclusions will provide the foundation for an extensive application of the combined method of ultrasound and chemical demulsifier.
    Type of Medium: Online Resource
    ISSN: 2090-9063 , 2090-9071
    URL: Article
    DOI: 10.1155/2017/9147926
    Language: English
    Publisher: Wiley
    Publication Date: 2017
    detail.hit.zdb_id: 2703077-5
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  • 8
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    Study on Quantum Radar Detection Probability Based on Flying-Wing Stealth Aircraft
    MDPI AG ; 2022
    In:  Sensors Vol. 22, No. 16 ( 2022-08-09), p. 5944-
    Details
    In: Sensors, MDPI AG, Vol. 22, No. 16 ( 2022-08-09), p. 5944-
    Abstract: The development of quantum radar technology presents a challenge to stealth targets, so it is necessary to study the quantum detection probability. In this study, an analytical expression of the quantum radar cross section (QRCS) for complex targets is presented. Based on this QRCS expression, a calculation method for the detection probability for quantum radar is creatively proposed. Moreover, a self-designed flying-wing stealth aircraft is adopted to obtain the detection probability distributions of the conventional radar and the quantum radar in different directions. As revealed by the result of this study, the detection probabilities of the quantum radar and the conventional radar are significantly different, and the detection probability of the quantum radar has obvious advantages in most regions with a certain distance.
    Type of Medium: Online Resource
    ISSN: 1424-8220
    URL: Article
    DOI: 10.3390/s22165944
    Language: English
    Publisher: MDPI AG
    Publication Date: 2022
    detail.hit.zdb_id: 2052857-7
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  • 9
    Online Resource
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    A Dynamic RCS and Noise Prediction and Reduction Method of Coaxial Tilt-Rotor Aircraft Based on Phase Modulation
    MDPI AG ; 2022
    In:  Sensors Vol. 22, No. 24 ( 2022-12-11), p. 9711-
    Details
    In: Sensors, MDPI AG, Vol. 22, No. 24 ( 2022-12-11), p. 9711-
    Abstract: For tilt-rotor aircraft with coaxial rotors (coaxial rotor aircraft), reduction of radar cross section as well as acoustic noise can be essential for stealth design, and the rotation of the coaxial rotors can have an influence on noise and dynamic radar cross section (RCS) characteristics. In this paper, an approach to the prediction of both the sound pressure level (SPL) of noise and the dynamic RCS of coaxial-tilt aircraft is carried out, based on the theories of the FW-H equation, the physics optics method (PO) and the physical theory of diffraction (PTD) method. In order to deal with the rotating parts (mainly including coaxial rotors), a generated rotation matrix (GRM) is raised, aiming at giving a universal formula for the time-domain grid coordinate transformation of all kinds of rotation parts with arbitrary rotation centers and rotation axis directions. Moreover, a compass-scissors model (CSM) reflecting the phase characteristics of coaxial rotors is established, and a method of noise reduction and RCS reduction based on the phase modulation method is put forward in this paper. The simulation results show that with proper CSM parameter combinations, the reduction of noise SPL can reach approximately 3~15 dB and the reduction of dynamic RCS can reach 1.6 dBsm at most. The dynamic RCS and noise prediction and reduction method can be meaningful for the radar-acoustic stealth design of coaxial tilt-rotor aircrafts.
    Type of Medium: Online Resource
    ISSN: 1424-8220
    URL: Article
    DOI: 10.3390/s22249711
    Language: English
    Publisher: MDPI AG
    Publication Date: 2022
    detail.hit.zdb_id: 2052857-7
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  • 10
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    Numerical Solutions of Fractional Integrodifferential Equations of Bratu Type by Using CAS Wavelets
    Wiley ; 2013
    In:  Journal of Applied Mathematics Vol. 2013 ( 2013), p. 1-7
    Details
    In: Journal of Applied Mathematics, Wiley, Vol. 2013 ( 2013), p. 1-7
    Abstract: A numerical method based on the CAS wavelets is presented for the fractional integrodifferential equations of Bratu type. The CAS wavelets operational matrix of fractional order integration is derived. A truncated CAS wavelets series together with this operational matrix is utilized to reduce the fractional integrodifferential equations to a system of algebraic equations. The solution of this system gives the approximation solution for the truncated limited 2 k ( 2 M + 1 ) . The convergence and error estimation of CAS wavelets are also given. Two examples are included to demonstrate the validity and applicability of the approach.
    Type of Medium: Online Resource
    ISSN: 1110-757X , 1687-0042
    URL: Article
    DOI: 10.1155/2013/801395
    Language: English
    Publisher: Wiley
    Publication Date: 2013
    detail.hit.zdb_id: 2062866-3
    detail.hit.zdb_id: 2578385-3
    SSG: 17,1
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