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As an important role to promote the comprehensive green transformation of airports, aircraft noise prediction around airports can help airports to grasp the noise situation, deploy management measures, and evaluate the effectiveness of noise reduction. In order to present the progress and grasp the research trend better, the relevant research and application at home and abroad were summarized by a literature review. The results show that the calculation method based on the noise-power-distance(DPD) curve and the prediction method driven by monitoring data were typically prediction methods according to different data sources. The former output prediction results at the cost of multi-parameter input and high computational burden, which was assisted by theoretical formulas. The latter constructed the prediction model by analyzing the noise propagation mechanism and mining the noise distribution, which relied on airport noise monitoring data. These methods had their own advantages and disadvantages and were highly complementary to applicate together, which can be an effective way to utilize advantages and complement weaknesses. Nowadays, it has become a research trend. Finally, a new prediction idea of air-ground joint and digital networking was proposed, which provided a reference for effectively promoting the integration of the two methods. [ABSTRACT FROM AUTHOR]

Copyright of Systems Engineering & Electronics is the property of Journal of Systems Engineering & Electronics Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Atomic Energy Science & Technology is the property of Editorial Board of Atomic Energy Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

To solve the problem of optimal course of anti-submarine aircraft in the process of searching submarine using magnetic detector, three indexes and a method for evaluating the ability of anti-submarine aircraft searching submarine by magnetic detector with different courses are proposed, on the basis of modeling and analysis of submarine magnetic field. Then the ability above is simulated and analyzed, and the result shows that the anti-submarine aircraft has the best detection effect along the north and south direction, and the worst detection effect along the east and west direction. [ABSTRACT FROM AUTHOR]

Copyright of Systems Engineering & Electronics is the property of Journal of Systems Engineering & Electronics Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Aerodynamic noise level has become an important performance index of civil aircraft, and it is drawing more and more attention. Most airframe noise research based on CFD method is aimed at aircraft individual parts at present, while lack of noise prediction for the complex high fidelity full aircraft model. Due to the interaction between aircraft parts, noise prediction between single part and the actual configuration are very different in the aspect of calculation conditions, noise generation and propagation. Only by using more realistic model can the noise be accurately predicted. In this paper, high-resolution mesh and high-precision hybrid RANS/LES method, combined with the FW-H acoustic analogy method, are employed to predict the noise of a turboprop's high-fidelity 1/6 scale model of landing configure. The improved delayed detached eddy simulation (IDDES) method was used to simulate the flow in the near-field sound source region, and the sound source characteristics of the whole turboprop are obtained. In addition to the two important noise sources-flap side edge and wing tip, numerical simulation also found other two important noise sources resulting from the interaction between parts-interaction between nacelle wake and flap, and the complex flow between flap inner side and fuselage. Results of far-field noise show that in the longitudinal symmetry plane of the fuselage, the noise mainly propagates to the lower front and over back direction, and the dipole characteristics are very obvious. In the plane perpendicular to the incoming flow, the noise in the transverse direction is weaker.

Copyright of Telecommunication Engineering is the property of Telecommunication Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

To solve the problem of low-frequency noise in aircraft cabin, a Helmholtz periodic structure with double labyrinth tubes was proposed in this paper. The design of labyrinth tubes greatly increases the length of tubes of Helmholtz resonator, reducing the lower limit of low-frequency band gap. The design of double opening tubes can increase the region of local resonance of the phononic crystal, therefore, the number of low-frequency band gaps increases. Firstly, the band structure and sound insulation characteristics of the structure in the frequency range from 0 Hz to 500 Hz were characterized by finite element method (FEM). It is found that the structure has multiple complete low-frequency band gaps in the frequency range from 0 Hz to 500 Hz, showing an excellent low-frequency sound insulation characteristic. Secondly, to reveal the mechanism of band gap, the equivalent circuit model was established by the method of electro-acoustic analogy. Finally, the influence factors of band gaps were analyzed by FEM and equivalent model. It is found that increasing the length of the tubes can effectively reduce the lower limit of the band gap, and a smaller lattice constant is beneficial to widen the band gap. The research in this paper further explores the influence of phononic crystal structure design on band gap and provides a new method for low-frequency noise reduction of aircraft cabin. [ABSTRACT FROM AUTHOR]

The comfort in helicopter cabin is significantly affected by the mid- and high-frequency noise caused by the main gearbox. Based on its noise transfer path, the development of cabin noise control technology is summarized in three aspects, including the supporting structure, the bulkhead and the internal cavity with passive, active and semi-active control methods. The results show that helicopter cabin noise in abroad is mainly controlled through the passive technologies such as damping vibration attenuation of panel, sound barrier with sealing, and sound absorption in cabin. However, some problems are appeared with respect to weight, economy, and limited control effect. The vibration reduction technology on the supporting structure has provided a new way for the efficient noise reduction of main gearbox, which has been combined with the comprehensive optimization to make some helicopters reach the cabin noise level of commercial aircraft. Nevertheless, the research and application of helicopter cabin noise control technology are inadequate in domestic. To obtain the new methods and ideas suitable for the helicopter development in China, the researches like the noise transmission mechanism, noise reduction design, verification and optimization should be further developed according to the realistic engineering application background of helicopters. [ABSTRACT FROM AUTHOR]

Copyright of Guangdong Architecture Civil Engineering is the property of Guangdong Architecture Civil Engineering Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Ｆｏｒ ａｉｒｃｒａｆｔ ｎｏｉｓｅ ａｎｄ ｖｉｂｒａｔｉｏｎ ｃｏｎｔｒｏｌ， ｉｔ ｉｓ ｖｉｔａｌｌｙ ｉｍｐｏｒｔａｎｔ ｔｏ ｉｄｅｎｔｉｆｙ ｄｙｎａｍｉｃ ｆｏｒｃｅｓ ｏｎ ｅｎｇｉｎｅ ｍｏｕｎｔｓ ｃａｕｓｅｄ ｂｙ ｅｎｇｉｎｅ ｏｐｅｒａｔｉｏｎ． Ａｌｔｈｏｕｇｈ ｓｕｃｈ ｄｙｎａｍｉｃ ｆｏｒｃｅｓ ａｒｅ ｎｅｅｄｅｄ ｔｏ ｐｒｅｄｉｃｔ ａｎｄ ｃｏｎｔｒｏｌ ｓｔｒｕｃｔｕｒａｌ ｖｉｂｒａｔｉｏｎ ａｎｄ ｓｔｒｕｃｔｕｒｅ⁃ｂｏｒｎｅ ｎｏｉｓｅ ｉｎ ｔｈｅ ｃａｂｉｎ， ｔｈｅｙ ｃａｎｎｏｔ ｂｅ ｍｅａｓｕｒｅｄ ｄｉｒｅｃｔｌｙ ｉｎ ｔｈｅ ｆｌｉｇｈｔ ｓｔａｔｅ． Ｔｈｅ ｌｅａｓｔ ｓｑｕａｒｅｓ ｍｅｔｈｏｄ ｗａｓ ｅｍｐｌｏｙｅｄ ｔｏ ｉｄｅｎｔｉｆｙ ｔｈｅ ｄｙｎａｍｉｃ ｆｏｒｃｅｓ ｂａｓｅｄ ｏｎ ｔｈｅ ｆｒｅｑｕｅｎｃｙ ｒｅｓｐｏｎｓｅ ｆｕｎｃｔｉｏｎ （ＦＲＦ） ｂｅｔｗｅｅｎ ｅｘｃｉｔａｔｉｏｎ ｐｏｉｎｔｓ ａｎｄ ｒｅｓｐｏｎｓｅ ｐｏｓｉｔｉｏｎｓ ｗｉｔｈ ｔｈｅ ａｃｔｕａｌ ａｃｃｅｌｅｒａｔｉｏｎ ｍｅａｓｕｒｅｍｅｎｔｓ ｉｎ ｔｈｅ ｆｌｉｇｈｔ ｓｔａｔｅ． Ａ ｎｏｒｍ ｃｏｎｄｉ⁃ ｔｉｏｎ ｎｕｍｂｅｒ ｃｒｉｔｅｒｉｏｎ ｗａｓ ｕｓｅｄ ｔｏ ｅｖａｌｕａｔｅ ｔｈｅ ａｃｃｕｒａｃｙ ｏｆ ｔｈｅ ｉｎｖｅｒｓｅ ｃａｌｃｕｌａｔｉｏｎ ｐｒｏｃｅｓｓ， ａｎｄ ｒｅｌａｔｉｖｅ ｅｒｒｏｒｓ ｏｆ ｔｈｅ ｐｒｅｄｉｃｔｅｄ ｄｙｎａｍｉｃ ｆｏｒｃｅｓ ｗｅｒｅ ｃａｌｃｕｌａｔｅｄ． Ｔｈｅ ｒｅｓｕｌｔｓ ｓｈｏｗ ｔｈａｔ， ｔｈｅ ｉｄｅｎ⁃ ｔｉｆｉｅｄ ｆｏｒｃｅｓ ｍｅｅｔ ｅｎｇｉｎｅｅｒｉｎｇ ｒｅｑｕｉｒｅｍｅｎｔｓ [ABSTRACT FROM AUTHOR]

The cabin area of civil aircraft with multi‑turbofan engines is vulnerable to beat noise during cruise flight. In order to find the method for restraining the beating noise，the beating noise model is established by using the pipe acoustic theory. It is clear that the beating noise mainly comes from the simple tone and harmonics of fan blade passing frequency. Applying the principle of linear superposition of sound wave，the mechanism of beating noise for double‑engine/four‑engine aircraft is analyzed，and the method for restraining beat noise is to make the physical speed of all engines consistent. During studying the beating noise for four‑engine aircraft，the formulas for calculating the interference of simple tone wave with different amplitudes and similar frequencies are derived，which provide a reference for restraining the beating noise of three‑engine aircraft and other multiple‑engine aircraft. Meanwhile，In order to promote the engineering application of this technology，the method of restraining beating noise by thrust management function of Boeing 787 aircraft is studied. The control law of restraining beating noise is designed. The upper and lower limits of beating noise frequency modulation are analyzed，and the corresponding recommended values are given. When aircraft system provides the N1 synchronization correction to engine electronic controller（EEC），it should compare the target speed for engine control. And EEC control engine should use the target speed which has been added with the N1 synchronization correction. [ABSTRACT FROM AUTHOR]

To predict and prevent the noise around the airport becomes an urgent problem. A new airport noise prediction model based on fuzzy support vector regression is established on the existing generic software for noise calculation. To integrate into the fuzzy support vector regression algorithm, the fuzzy membership of each sample is determined by its local outlier factor. Finally, the prediction accuracy, noise immunity, generalization ability of the proposed model are validated on the historic flight data of an airport. Experiments show that the fuzzy support vector regression algorithm based on local outlier factor can effectively predict the noise levels around airports, and is more accurate and better noise immunity than the standard support vector regression. [ABSTRACT FROM AUTHOR]

According to the characteristics of airport noise data, a fast hierarchical clustering algorithm based on representative point is presented. This algorithm improves the traditional condensed hierarchical clustering algorithm by using clustering representative point method and dichotomy strategy. Meanwhile, a clustering result evaluation method which combines the clustering representative point and the definition of similarity in clustering algorithm is proposed. The experimental results show that the proposed algorithm not only has high performance, but also can discover the noise distribution model of a specific type of flight event correctly. The method can accurately predict the noise distribution model of these flight events. [ABSTRACT FROM AUTHOR]

Active noise control technology on 3D space is a hot spot issue in the field of noise control, which has great significance to reduce the noise of aircraft or vehicle. In this paper, a method of control noise on 3D space is developed. First of all, modeling and meshing is established for the 3D space. The quadratic sum of sound pressure of all parts is used as an error criterion. Then, the secondary sound source strength is obtained in the case that the error criterion is minimal. Finally, the result of simulation and test of the active noise control system validates the correctness and effectiveness of this method. [ABSTRACT FROM AUTHOR]