Journal articles on the topic 'Noise Path Model'
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1
Yuan, Jing. "Noninvasive Model Independent Noise Control with Adaptive Feedback Cancellation." Advances in Acoustics and Vibration 2008 (March 17, 2008): 1–7. http://dx.doi.org/10.1155/2008/863603.
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An active noise control (ANC) system is model dependent/independent if its controller transfer function is dependent/independent on initial estimates of path models in a sound field. Since parameters of path models in a sound field will change when boundary conditions of the sound field change, model-independent ANC systems (MIANC) are able to tolerate variations of boundary conditions in sound fields and more reliable than model-dependent counterparts. A possible way to implement MIANC systems is online path modeling. Many such systems require invasive probing signals (persistent excitations) to obtain accurate estimates of path models. In this study, a noninvasive MIANC system is proposed. It uses online path estimates to cancel feedback, recover reference signal, and optimize a stable controller in the minimum H2 norm sense, without any forms of persistent excitations. Theoretical analysis and experimental results are presented to demonstrate the stable control performance of the proposed system.
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Karttunen, Aki, Mikko Valkama, and Jukka Talvitie. "Influence of Noise-Limited Censored Path Loss on Model Fitting and Path Loss-Based Positioning." Sensors 21, no. 3 (February 2, 2021): 987. http://dx.doi.org/10.3390/s21030987.
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Positioning is considered one of the key features in various novel industry verticals in future radio systems. Since path loss (PL) or received signal strength-based measurements are widely available in the majority of wireless standards, PL-based positioning has an important role among positioning technologies. Conventionally, PL-based positioning has two phases—fitting a PL model to training data and positioning based on the link distance estimates. However, in both phases, the maximum measurable PL is limited by measurement noise. Such immeasurable samples are called censored PL data and such noisy data are commonly neglected in both the model fitting and in the positioning phase. In the case of censored PL, the loss is known to be above a known threshold level and that information can be used in model fitting and in the positioning phase. In this paper, we examine and propose how to use censored PL data in PL model-based positioning. Additionally, we demonstrate with several simulations the potential of the proposed approach for considerable improvements in positioning accuracy (23–57%) and improved robustness against PL model fitting errors.
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Kajikawa, Yoshinobu, and Yasuo Nomura. "An active noise control system without secondary path model." Electronics and Communications in Japan (Part III: Fundamental Electronic Science) 83, no. 10 (October 2000): 47–55. http://dx.doi.org/10.1002/(sici)1520-6440(200010)83:10<47::aid-ecjc6>3.0.co;2-t.
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Liu, Ningning, Yuedong Sun, Yansong Wang, Pei Sun, Wenwu Li, and Hui Guo. "Mechanism of interior noise generation in high-speed vehicle based on anti-noise operational transfer path analysis." Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering 235, no. 1 (July 15, 2020): 273–87. http://dx.doi.org/10.1177/0954407020937219.
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Owing to the continuous development of the automobile industry, increasingly stringent performance requirements for noise, vibration, and harshness of automobiles are being presented. Interior noise control in high-speed vehicles has not been adequately addressed, owing to the complex mechanism of noise generation. As simulations performed previously focused on vehicle wind noise and tyre noise cannot adequately predict the effect on passenger ear-side noise, these issues are investigated in this study. Their effects on passengers are investigated using transfer path analysis. An anti-noise operational transfer path analysis is proposed to study noise generated in high-speed vehicles. The established anti-noise operational transfer path analysis model can eliminate crosstalks between noise source signals of different transmission paths. The model is validated by comparing the measured and calculated values of the anti-noise operational transfer path analysis model. The coherence of the input noise signal and the ear-side noise signal of the passenger is assessed using coherence analysis. By calculating and categorising the contributions of different noise sources in different locations and types, the main noise sources affecting passenger comfort are determined. The result indicates that the main noise sources affecting the passenger’s ear-side noise change from engine noise to left-A wind noise and tyre radiation noise with increasing vehicle speed, in which the proportion also increase. The proposed anti-noise operational transfer path analysis is suitable for the interior-noise analysis of high-speed vehicles, and this study may serve as a reference for future studies regarding active and passive noise control in high-speed vehicles.
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Zhang, Qi-Zhi, Woon-Seng Gan, and Ya-li Zhou. "A Model Predictive Algorithm for Active Control of Nonlinear Noise Processes." Shock and Vibration 12, no. 3 (2005): 227–37. http://dx.doi.org/10.1155/2005/573067.
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In this paper, an improved nonlinear Active Noise Control (ANC) system is achieved by introducing an appropriate secondary source. For ANC system to be successfully implemented, the nonlinearity of the primary path and time delay of the secondary path must be overcome. A nonlinear Model Predictive Control (MPC) strategy is introduced to deal with the time delay in the secondary path and the nonlinearity in the primary path of the ANC system. An overall online modeling technique is utilized for online secondary path and primary path estimation. The secondary path is estimated using an adaptive FIR filter, and the primary path is estimated using a Neural Network (NN). The two models are connected in parallel with the two paths. In this system, the mutual disturbances between the operation of the nonlinear ANC controller and modeling of the secondary can be greatly reduced. The coefficients of the adaptive FIR filter and weight vector of NN are adjusted online. Computer simulations are carried out to compare the proposed nonlinear MPC method with the nonlinear Filter-x Least Mean Square (FXLMS) algorithm. The results showed that the convergence speed of the proposed nonlinear MPC algorithm is faster than that of nonlinear FXLMS algorithm. For testing the robust performance of the proposed nonlinear ANC system, the sudden changes in the secondary path and primary path of the ANC system are considered. Results indicated that the proposed nonlinear ANC system can rapidly track the sudden changes in the acoustic paths of the nonlinear ANC system, and ensure the adaptive algorithm stable when the nonlinear ANC system is time variable.
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Liu, Qiang, Xuanyi Zhou, Jianxin Zhu, and Xiaoping Gong. "Optimization of Noise Transfer Path Based on the Composite Panel Acoustic and Modal Contribution Analysis." Complexity 2021 (November 20, 2021): 1–15. http://dx.doi.org/10.1155/2021/3059865.
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The noise of a cab directly affects the comfort and labor efficiency of the operators. The optimization of the structure-borne transmission path can obviously reduce the cab noise. The method of panel acoustic contribution analysis (PACA) is used to reduce structure noise. However, most studies only consider the panel acoustic contribution of a single frequency, without considering the contribution of major frequencies synthesis to confirm the optimized panels. In this paper, a novel method is proposed based on composite panel acoustic and modal contribution analysis and noise transfer path optimization in a vibro-acoustic model. First, the finite element model (FEM) and the acoustic model are established. Based on the acoustic transfer vector (ATV) method, a composite panel acoustic contribution analysis method is proposed to identify the panels affecting the noise of the field point. Combined with the modal acoustic contribution of the modal acoustic transfer vector (MATV) method, the noise field point is confirmed in the area which has the most significant influence. Second, the optimization algorithm NLOPT which is a nonlinear optimization is applied to design the areas. The noise transfer path optimization with vibroacoustic coupling response can quickly determine the optimal thickness of the panels and reduce low-frequency noise. The effectiveness of the proposed method is applied and verified in an excavator cab. The sound pressure level (SPL) the driver’s right ear (DRE) decreased obviously. The acoustic analysis of the composite panel acoustic contribution and modal acoustic contribution can more accurately recognize an optimized area than the traditional PACA. This method can be applied in the optimization of the structure-borne transmission path for construction machinery cab and vehicle body.
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Zhang, Yu, Dan Zhang, Zhen Han, and Peng Jiang. "A Joint Denoising Learning Model for Weight Update Space–Time Diversity Method." Remote Sensing 14, no. 10 (May 19, 2022): 2430. http://dx.doi.org/10.3390/rs14102430.
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Space–time diversity (STD) has been widely applied in underwater acoustic (UWA) communication due to its exceptional anti-multipath performance. However, underwater noise can seriously affect the processing results of STD. The conventional filtering algorithms cannot deal with the nonlinear components of underwater noise and may not work well for complex-type signals. This study proposes an improved STD method with a joint noise-reduction learning model for the above issues. We construct a noise-reduction learning model dedicated to complex-type UWA signals in the first stage. Complex-type features based on UWA data are extracted for pre-processing data, and a conditional generative adversarial network (CGAN) is used as the backbone network for noise-reduction. Residual learning is used to accomplish noise cancellation and yield noise-reduction estimates. In the second stage, an STD structure based on a weight update strategy is constructed. The STD structure can further constrain the weights of the signals from the main path, enhance the reception of the main path, and suppress the multi-access interference (MAI) caused by the spread spectrum communication. Finally, combining the signals on each path can improve the communication quality of the system based on the principle of the maximum signal-to-interference plus noise ratio (SINR). The simulation and experiments on a lake showed that the proposed method is more robust over the changing signal-to-noise ratio (SNR) and has a lower bit error rate (BER) than conventional methods.
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Pan, F., and J. D. Jones. "Gas Path Sound Transmission in Spherically-Shaped Reciprocating Compressors: Theory and Experiment." Journal of Vibration and Acoustics 121, no. 1 (January 1, 1999): 8–17. http://dx.doi.org/10.1115/1.2893954.
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Gas pulsations within the refrigerant gas cavity is one of the principal noise propagating paths in reciprocating compressors. This paper provide a physical insight to the relationship between the gas pulsations inside the cavity and noise radiation of reciprocating compressors. The refrigerant gas cavity of the test compressor is modeled as a space between concentric spherical shells and analyzed with modal expansion techniques. Gas pulsations within the cavity are mathematically represented as the forcing terms of the inhomogeneous wave equation in spherical coordinates. The pressure distribution inside the cavity is then estimated accordingly. Based on the orthogonality principles, the noise radiation patterns associated with the gas pulsations are predicted. Acoustic modal analysis, directivity test and running speed sensitivity test are conducted to identify the acoustic characteristics of cavity and to verify the analytical model. The experimental results are in good agreement with the prediction of the analytical model. Thus, the concentric, spherical shell model well describes the acoustic characteristics of cavity within the test compressor. This model can also be employed as a design tool to analyze the effects of system parameter variation on overall noise radiation.
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Ong, Duu Sheng, Ai Hui Tan, Kan Yeep Choo, Keat Hoe Yeoh, and John P. R. David. "Weibull-Fréchet random path length model for avalanche gain and noise in photodiodes." Journal of Physics D: Applied Physics 55, no. 6 (November 2, 2021): 065105. http://dx.doi.org/10.1088/1361-6463/ac31f0.
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Abstract A four-parameter Weibull-Fréchet (WF) distribution function has been introduced in the random path length (RPL) model for nonlocal modelling of soft-threshold ionisation in semiconductors. The WF function has been demonstrated to be capable of reproducing the realistic probability distribution function (PDF) of electron and hole ionisation path lengths extracted from full band Monte Carlo (FBMC) transport simulations of bulk GaAs. The electron-initiated multiplication in GaAs avalanche photodiodes (APDs) calculated by the WF-RPL model is in excellent agreement with the results from FBMC. The predicted excess noise factor is closer to that of FBMC as compared to the hard threshold RPL model. The advantage of this improved RPL model as a tool for predicting the PDF of electron and hole ionisation path lengths in AlAs0.56Sb0.44 from the experimentally measured avalanche gain and noise has been analysed. The electron ionisation path length PDF of AlAs0.56Sb0.44 has a unique feature of two decay rates with a narrow full width at half maximum and a long tail. The extremely low hole ionisation coefficient in AlAs0.56Sb0.44 is found with a PDF of ionisation path length spanning over 50 µm at an electric field of 600 kVcm−1, supporting the very low hole feedback ionisation in AlAs0.56Sb0.44 APDs. The combination of the detailed and peaked electron’s ionisation path length PDF and of the broad hole’s ionisation path length PDF is responsible for the extremely low avalanche noise in the 1.55 µm thick AlAs0.56Sb0.44 APDs.
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Qian, Kun, Zhichao Hou, Jie Liang, Ruixue Liu, and Dengke Sun. "Interior Sound Quality Prediction of Pure Electric Vehicles Based on Transfer Path Synthesis." Applied Sciences 11, no. 10 (May 12, 2021): 4385. http://dx.doi.org/10.3390/app11104385.
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The interior sound quality (SQ) of pure electric vehicles (PEVs) has become an important consideration for users purchasing vehicles. At present, it is insufficient to take the sound pressure level as the interior acoustics design index of PEVs. Transfer path analysis (TPA) and transfer path synthesis (TPS) that take the SQ of interior noise as the improvement target remains in the preliminary exploration stage. In this paper, objective psychoacoustic parameters of SQ were taken as evaluation indexes of interior PEV noise. A virtual interior SQ synthesis model was designed on the basis of TPA and TPS, which combines experimentation and simulation. The SQ synthesis model demonstrates each noise component contribution in a PEV by new SQ separation technology. First, the interior noise transfer path and noise source of the PEV were determined in a synthesis analysis method of the interior PEV noise. Second, on the basis of the composition mechanism of interior noise and the basic principle of TPA, the excitation signal and transfer function of each interior noise path in the PEV were tested. On the basis of TPS, the interior SQ synthesis model of PEV was then established. Finally, the accuracy of the prediction model was verified in simulation and experimental comparison studies on the psychoacoustic objective parameters of SQ. The SQ objective parameter value of each transfer path was quantified by using contribution analysis. The results are expected to improve the comfort of the interior acoustic environment and enhance the competitiveness of vehicle products. They also provide an effective reference and new ideas for the development of interior SQ in PEVs.
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Ren, Xing, and Hongwei Zhang. "Active noise control without secondary path modeling: algorithm and implementation." INTER-NOISE and NOISE-CON Congress and Conference Proceedings 263, no. 5 (August 1, 2021): 1919–28. http://dx.doi.org/10.3397/in-2021-1995.
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Active noise control (ANC) has been intensively studied for decades. The most classical ANC algorithm should be the filtered-x least mean square (FxLMS) algorithm, which needs the model of the secondary path to work. Thus, the residual error of the ANC system is closely related to the preciseness of the secondary path model. In many applications, the secondary path is often time-varying. Therefore, off-line identification of the secondary path is not applicable. However, on-line identification often requires an additional white noise as a stimulating signal of the secondary path, which will deteriorate the final noise reduction effect. This paper proposes an improved artificial bee colony (ABC) algorithm for ANC system, which does not require identification of the secondary path. In order to guarantee the convergence of the algorithm and accelerate the convergence speed, this paper introduces a variable forgetting factor into the fitness function, and improves the traditional ABC algorithm by integrating LMS algorithm into the ABC algorithm. A single channel ANC system equipped with an FPGA hardware platform is set up in an anechoic chamber, and experiments show that the proposed algorithm can produce a satisfactory noise reduction effect without modeling the secondary path.
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Pan, Yang, Rui Liu, and Xiao hui He. "Study on noise reduction method of main noise transmission path of axial piston pump with new damping material." Noise Control Engineering Journal 70, no. 6 (November 1, 2022): 485–96. http://dx.doi.org/10.3397/1/377042.
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Axial piston pump is complex fluid machinery with mechanical fluid coupling, and it has the characteristics of multiple noise sources. In order to solve the high noise problem of axial piston pump, this paper proposes a noise reduction method by identifying the main noise sources of axial piston pump and laying new damping materials to reduce noise. It breaks through the existing method of optimizing the parameters of piston pump shell and valve plate structure. A multi-parameter trajectory sensitivity identification and noise reduction method for vibration transmission path of axial piston pump is proposed in this paper. First, the lumped parameter method is used to establish the mathematical model of vibration transmission path of axial piston pump. The sensitivity of structural vibration response to transmission path multi-parameters are analyzed based on trajectory sensitivity method. The most sensitive parameters in the main noise transmission path are determined. Then, the experimental study of radiated noise transmission path of axial piston pump is carried out. A new type of viscous damping material is proposed to reduce the noise on the transmission path of the main noise source. The experimental results show that the noise of piston pump is reduced by 2.32 dB. The research results provide a new method and way for the design and manufacture of low noise piston pump.
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Yang, Xiuyi, Hongjie Yin, Feng Zhang, and Jing Nie. "Quantum coherence protection by noise." Laser Physics Letters 19, no. 7 (May 19, 2022): 075202. http://dx.doi.org/10.1088/1612-202x/ac6e6f.
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Abstract In this paper, we propose a scheme to protect quantum coherence by adding another noise. We consider an example of a Jaynes–Cummings model coupled to an external non-Markovian bosonic bath. We solve this model by using the dressed state method in the presence of a stochastic coupling and obtain the density matrix by numerically averaging many stochastic trajectories. We show that the noisy atom-cavity coupling can effectively suppress both the relaxation and dephasing effects caused by the leakage of the cavity. Besides, we further illustrate the impacts of the standard deviation of the noisy coupling and the non-Markovian memory effect on the coherence protection. Then, the mechanism of the protection is analyzed. It is our hope that our research may open a new path to consider the role of noise in quantum coherence preservation.
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Han, Hyun-Woo, Min-Woo Kang, Seung-Je Cho, and Young-Jun Park. "Component-based transfer path analysis on agricultural tractor." INTER-NOISE and NOISE-CON Congress and Conference Proceedings 266, no. 1 (May 25, 2023): 1304–10. http://dx.doi.org/10.3397/nc_2023_0177.
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Agricultural tractors are special purpose machines that perform agricultural operation in harsh environments such as unpaved roads and farmlands, and generate high levels of noise and vibration. Eco-friendly tractors using electric drivetrains and hydrogen fuel cells are being developed to reduce exhaust gas in accordance with global environmental regulations. Unlike traditional tractor structures, these electrified tractors are being developed as modular and shared platforms. Therefore, it is changing into a system that is easy to apply component-based transfer path analysis (C-TPA) to reduce noise and vibration of tractors. In this paper, the noise and vibration contributions of an agricultural tractor were analyzed using C-TPA, and the blocked force usable as the excitation force of the virtual model was derived. The accuracy of transfer path analysis was improved by applying transfer functions including the rotational directions using virtual point transformation technique. The prediction result of developed experimental model were similar to the vibration response of the actual tractor, and the contribution of structure-borne noise could be quantitatively evaluated.
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Yuxue, Pu, and Shu Pengfei. "Online secondary path modeling method with auxiliary noise power scheduling strategy for multi-channel adaptive active noise control system." Journal of Low Frequency Noise, Vibration and Active Control 38, no. 2 (February 19, 2019): 740–52. http://dx.doi.org/10.1177/1461348419831119.
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Accurate model of secondary paths is very crucial for the multi-channel filtered-X least mean square algorithm applied in adaptive active noise control system. The auxiliary random noise technique is popular for online secondary path modeling during adaptive active noise control operation. This paper proposes a simplified variable step-size strategy and an effective auxiliary noise power scheduling strategy for the multi-channel filtered-X least mean square algorithm. Through a defined indirect error signal, the proposed method can guarantee every online secondary path modeling filter has its own exclusive variable step-size strategy to update their coefficients, and every injected noise has its own exclusive scheduling strategy considering all of the corresponding online secondary path modeling filters. The proposed method can improve the adaptive performance and simplifies the complexity of multi-channel adaptive active noise control system. Computer simulations show that the proposed method gives much better noise reduction and secondary path modeling accuracy at a somewhat faster convergence rate comparing with the competing methods.
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Gao, Yin Han, Zhi Bo Wang, Jie Liang, Li Tong Zhang, Ying Jie Liu, and Wen Jun Jiang. "Noise Transfer Function Refinement of Commercial Vehicle Cab Based on the Vibro-Acoustic Model." Applied Mechanics and Materials 551 (May 2014): 284–89. http://dx.doi.org/10.4028/www.scientific.net/amm.551.284.
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The TPA method has gradually developed into a mature approach to solve the internal noise problem of vehicles in recent years. Among the excitation transfer path from excitation to the noise at the target point, the noise transfer function is an important path. The noise transfer function is an inherent property of the commercial vehicle cab like the modes. When noise transfer function is low; the noise caused by the vibration transformed from the suspension is relatively low, which will be great help for the comfort of the cab. A vibro-acoustic model of some commercial vehicle cab has been built in this research, and the low frequency region noise transfer function from the mount points to the driver's ears has been simulated. From the comparison of the numerical result and the relevant test result, the accuracy of the simulation model has been proved. For the sensitive frequencies, the vibro-acoustic modes have larger vibration on some thin plates, which has been proved to be the reason for the peak for the noise transfer function. In order to reduce the noise transfer function, damping materials were applied to the sensitive thin plates, the modification effect proved to be content in the real working condition.
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Haseeb, Abdul, Muhammad Tufail, Shakeel Ahmed, Muhammad Rehan, Amna Majid, and Waqas Ahmed. "A Fuzzy Logic-Based Gain Scheduling Method for Online Feedback Path Modeling and Neutralization in Active Noise Control Systems." Fluctuation and Noise Letters 19, no. 01 (August 22, 2019): 2050008. http://dx.doi.org/10.1142/s021947752050008x.
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Acoustic feedback is the main problem associated with (broadband) active noise control (ANC) in feed-forward configuration. To solve this problem, auxiliary noise is injected into the ANC system to have accurate model of the feedback path. The conventional approaches substantially model the feedback path at the cost of degradation in the noise reduction performance (NRP) and vice versa. Here, we propose a fuzzy logic-based gain scheduling (of auxiliary noise) for online feedback path modeling and neutralization (FBPMN). The fuzzy controller computes the instantaneous gain for auxiliary noise based on two inputs, the first input gives information about modeling status of FBPMN filter while the second input gives information regarding variance of the disturbance signal for the adaptive FBPMN filter. Furthermore, variable step-size (VSS) is used for the adaptation of FBPMN filter that uses a larger value of step-size during modeling (phase) of FBPMN filter for fast adaptation and a smaller value when the feedback path has been (adequately) modeled. Fuzzy gain scheduler together with VSS in FBPMN filter improves both the NRP and feedback path modeling characteristics. Moreover, the proposed method does not require initial offline modeling of the feedback path thereby demonstrating complete online operation. To make the system computationally efficient, a look-up table-based approach is also proposed in this paper. Simulations results are presented to demonstrate the effectiveness of the proposed method.
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Yuan, Jun, Jun Li, Anfu Zhang, Xiangdong Zhang, and Jia Ran. "Active Noise Control System Based on the Improved Equation Error Model." Acoustics 3, no. 2 (May 31, 2021): 354–63. http://dx.doi.org/10.3390/acoustics3020024.
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This paper presents an algorithm structure for an active noise control (ANC) system based on an improved equation error (EE) model that employs the offline secondary path modeling method. The noise of a compressor in a gas station is taken as an example to verify the performance of the proposed ANC system. The results show that the proposed ANC system improves the noise reduction performance and convergence speed compared with other typical ANC systems. In particular, it achieves 28 dBA noise attenuation at a frequency of about 250 Hz and a mean square error (MSE) of about −20 dB.
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Kharchenko, Volodymyr, Yuri Barabanov, and Andrii Grekhov. "MODELING OF ADS-B DATA TRANSMISSION VIA SATELLITE." Aviation 17, no. 3 (October 7, 2013): 119–27. http://dx.doi.org/10.3846/16487788.2013.840057.
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For modelling transmission of ADS-B messages via low-orbit satellite constellation Iridium, the original model of a communication channel “Aircraft-to-Satellite-to-Ground Station” was built using MATLAB Simulink. The model comprises “Aircraft Uplink Transmitter” (Bernoulli Random Binary Generator, Convolutional Encoder, BPSK Baseband Modulator, High Power Amplifier with a memoryless nonlinearity, Transmitter Dish Antenna Gain), “Uplink Path” (Free Space Path Loss, Phase/Frequency Offset), “Satellite Transponder” (Receiver Dish Antenna Gain, Satellite Receiver System Temperature, Complex Baseband Amplifier, Phase Noise, Transmitter Dish Antenna Gain), “Downlink Path” (Free Space Path Loss, Phase/Frequency Offset), “Ground Station Downlink Receiver” (Receiver Dish Antenna Gain, Ground Receiver System Temperature, Viterbi Decoder), “Error Rate Calculation” block and “Display”. The modelling was realized without and with convolutional coding (r = 3/4, K = 7) at different noise temperatures and free space losses. Dependencies of a Bit Error Rate on free space path losses, antenna's diameter, phase/frequency off-sets, satellite transponder linear gain, aircraft and satellite transponder high power amplifier back-off level, and phase noise were received and analysed.
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Liu, Xia, Hua Jin Yan, Xiu Jie Liu, and Xia Sun. "Analysis and Study of the Transmission Path Based on the Body and NVH." Applied Mechanics and Materials 385-386 (August 2013): 272–75. http://dx.doi.org/10.4028/www.scientific.net/amm.385-386.272.
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In the field of automotive engineering, noise and vibration in the car comes mainly from the engine and the road passed through the body, suspension, mount and exhaust system path to the car or reverberation. So this article , a model of white body transfer path analysis and research, improves the rigidity of white body, to reduce noise, vibration, and weight is reduced, and find out the resonance phenomena because of insufficient stiffness of car body, combining body CAE modal analysis results provide the theoretical basis for the optimization of structural damping.
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Li, Duo. "Urban Planning Image Feature Enhancement and Simulation Based on Partial Differential Equation Method." Advances in Mathematical Physics 2021 (September 1, 2021): 1–10. http://dx.doi.org/10.1155/2021/1700287.
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Based on the introduction of the basic ideas and related technologies of partial differential equations, as well as the method of path planning, the application of partial differential equations in solving urban path planning is studied. The path planning model of partial differential equations and the setting of obstacle boundary conditions are introduced, and adaptive. Theoretical research and experimental results show that it is feasible and effective to solve urban path planning by partial differential equations, which provides a new way for urban path planning research ideas and methods. This paper proposes an image detection algorithm based on diffusion equation. According to the logarithmic transformation, the multiplicative speckle noise in the image can be converted into additive noise. We first perform logarithmic transformation on the image and then use the denoising model of the diffusion equation to filter out the noise in the image and then use the logarithm to recognize the image. The difference image is obtained by the domain difference method, and finally, the difference image is classified by the clustering algorithm, and the change area is extracted. Experiments show that the algorithm can effectively reduce the effect of multiplicative speckle noise on the change detection results, improve the accuracy of change detection, and shorten the change detection time. This article takes the path planning problem of a two-dimensional space city as an example to discuss the application of partial differential equations. According to the principle of energy conservation, this paper uses the two-dimensional space radiant heat conduction equation as an example to model and illustrate the solution of the path planning problem.
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Lu, Ming-Hung, Ming Une Jen, and Dennis de Klerk. "Case study: Separating source contributions of vehicle interior noise by operational transfer path analysis." Noise Control Engineering Journal 69, no. 1 (January 1, 2021): 39–52. http://dx.doi.org/10.3397/1/37694.
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The perception of vehicle interior noise is a key quality index to customers and automakers alike. By tracing noise back to key noise sources and paths, one can focus their refinement efforts. Aiming at the most efficient way to identify the primary noise sources in a vehicle cabin, this article establishes a framework of operational transfer path analysis (OTPA) for separating contributions of noise sources by operational measurements only. OTPA model design, measuring essentials and synthesis method used for separating vehicle interior noise contributions from the powertrain, tires andwindwere described in detail. To comprehend the implementation of OTPA on noise source separation, this article also addresses an exemplification study on an electric vehicle. In the case study illustrated, both spectral map and order extractions were used to validate if the OTPA synthesized results of the powertrain noise contribution agreed with the measured results. Tire noise contribution was validated using the tires driven by the dynamometer along with all other systems switched off. With well-validated OTPA model for the powertrain and tires, further individual path breakdown of the powertrain and tire noise then was investigated to identify key contributors to the interior noise. After clearly separating interior noise contributions, one therefore could design effective countermeasures to mitigate the dominant noise sources. With appropriate scheme of measurement and synthesis, the OTPA technique could therefore effectively serve target setting and refinement focus at foremost noise contributors.
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Yu, Qing, and Xianbin Liu. "Noise-induced transition in the Zeldovich–Semenov model with local and global bifurcations." Journal of Statistical Mechanics: Theory and Experiment 2022, no. 1 (January 1, 2022): 013207. http://dx.doi.org/10.1088/1742-5468/ac3e73.
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Abstract The noise-induced transition of the Zeldovich–Semenov model in a continuous stirred tank reactor is investigated under small random perturbations. The deterministic model will exhibit mono- and bistable characteristics via local and global bifurcations. In the bistable zone, based on the Freidlin–Wentzell large deviation theory, the stochastic preference is explained by analyzing the required action of the fluctuational path. For the case of monostability, in the weak noise limit, the emergence of the switching line gives rise to the sudden switch of the optimal path and the sliding cycle will appear via the sliding bifurcation, which is verified by numerical methods. In addition, when there is no saddle in phase space, stochastic excitation with large-amplitude spikes is studied. On the quasi-threshold manifold, the point with the minimum quasi-potential plays the same role as the saddle, which means that the optimal path will undergo a large excursion by crossing this special point. These phenomena are verified by employing stochastic simulations.
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Główka, Teresa, and Jarosław Figwer. "A Higher-Order Spectra Based Method of On-Line Secondary Path Model Identification for Active Noise Control Systems." Solid State Phenomena 248 (March 2016): 3–10. http://dx.doi.org/10.4028/www.scientific.net/ssp.248.3.
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The aim of this paper is to present a method of nonparametric and parametric secondary path model identification for adaptive active noise control systems with low-power non-Gaussian excitations of the form of a higher-order discrete-time multisine random process and data processing based on cross-higher-order spectra. Properties of the discussed method are illustrated by simulation experiments devoted to secondary path identification for feedforward and feedback active noise control systems. Its robustness to nonlinear distortions implied by data acquisition system and adaptation procedure is proved.
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Yu, Gen Jian, and Wei Lin Tu. "Node Positioning Model for UWB Wireless Sensor Networks." Applied Mechanics and Materials 475-476 (December 2013): 432–35. http://dx.doi.org/10.4028/www.scientific.net/amm.475-476.432.
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A node positioning model of UWB wireless sensor networks is proposed, and positioning error of the model is investigated through simulation. High accuracy of positioning is achieved if all four reference nodes have LOS(Line of Sight) information path, however, even if one reference node does not have a LOS information path, the positioning error will no less than 5 m when the SNR(Signal to Noise Rate) lower than 30 dB, so the SNR or reference node should be increased to assure the positioning accuracy.
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SATO, Hiroki, and Toshimi SIMIZU. "356 Active Noise Control with a Howling filter without the Path Model." Proceedings of Yamanashi District Conference 2012 (2012): 96–97. http://dx.doi.org/10.1299/jsmeyamanashi.2012.96.
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Zhang, Rui, Jiyan Yi, Hesheng Tang, Jiawei Xiang, and Yan Ren. "Fault Diagnosis Method of Waterproof Valves in Engineering Mixing Machinery Based on a New Adaptive Feature Extraction Model." Energies 15, no. 8 (April 11, 2022): 2796. http://dx.doi.org/10.3390/en15082796.
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Due to the complex working medium of oil in construction engineering, the waterproof valve in mixing machinery can easily cause different degrees of failure. Moreover, under adverse working conditions and complicated noise backgrounds, it is very difficult to detect the fault of waterproof valves. Thus, a fault diagnosis method is proposed, especially for the fault detection of waterproof valves as a key component in the construction of mixing machinery. This fault diagnosis method is based on a new adaptive feature extraction model, with multi-path signals to the improved deep residual shrinkage network–stacked denoising convolutional autoencoder (named DRSN–SDCAE). Firstly, the noisy vibration signals collected by the two vibration sensors are preprocessed, and then transmitted to the parallel structure improved DRSN–SDCAE for adaptive denoising and feature extraction. Finally, these results are fused through the feature fusion strategy to realize the effective fault diagnosis of the waterproof valve. The effectiveness of this method was verified through theory and experiments. The experimental results show that the proposed fault diagnosis method based on the improved DRSN–SDCAE model can automatically and effectively extract fault features from noise for fault diagnosis without relying on signal processing technology and diagnosis experiences. When compared with other intelligent fault diagnosis methods, the features extracted from multi-path inputs were more comprehensive than those extracted from single-path inputs, and contained more complete features of hidden data, which significantly improved fault diagnosis accuracy based on these fault features. The contribution of this paper is to learn fault features autonomously in signals with strong and complex noise through a deep network structure, which extends the fault diagnosis method to the field of construction machinery to improve the safe operation and maintainability of engineering machinery.
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Kharchenko, Volodymir, Bo Wang, Andrii Grekhov, and Anna Leschenko. "MODELLING THE SATELLITE COMMUNICATION LINKS WITH ORTHOGONAL FREQUENCY-DIVISION MULTIPLEXING." TRANSPORT 31, no. 1 (January 28, 2015): 22–28. http://dx.doi.org/10.3846/16484142.2014.1003599.
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Global technologies of data transmission in real time are developing constantly. Therefore, modelling of messages transmission through satellite constellations is an actual problem. In this paper the original model of a communication channel ‘Vehicle-to-Satellite-to-Ground Station’ based on principles of the IEEE 802.11a standard is designed using MatLab Sіmulіnk software. The model allows simulating data transmission with data rate from 6 to 54 Mbit/s using adaptive modulation. Two types of channels were analysed for uplink/downlink modulation – a free space path losses with phase/frequency offset and Additive White Gaussian Noise (AWGN) link. On the base of this model, channel integrity was investigated and dependences of a Signal-Noise Ratio (SNR) on free space path losses, antennas diameters, number of OFDM symbols and satellite transponder noise temperature were received.
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Mohamed, Eid Saber, Shawki Abouel-Seoud, Manar Eltantawie, Abdelfattah Mohamded, and Mohamed Salah. "Improved vehicle interior structure-borne noise induced by the powertrain using parallel dry friction damper." Journal of Low Frequency Noise, Vibration and Active Control 37, no. 2 (August 31, 2017): 295–312. http://dx.doi.org/10.1177/1461348417725951.
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Because of the higher requirements for vehicle comfort and people’s increasing ecological consciousness, research on the interior noise in a vehicle has received wide attention, among which structure-borne noise is hard to diagnose. To solve the problem, the transfer path analysis method of powertrain structure-borne noise has been systematically analyzed. By introduction of the powertrain source-path-receiver model, this method enables the researchers to estimate and study the noise, vibration, and harshness transfer functions and their operational forces. The aim is to further improve noise, vibration, and harshness with minimal negative impact on other vehicle attributes, such as ride comfort, handling, drivability, durability, etc. In this article, a parallel dry friction damper was added to the vehicle nearside powertrain mount, which is the most significant one to the receiver of passenger vehicle for improving its interior structure-borne noise induced by the engine. The test vehicle was a midsize executive vehicle. Since the structure-borne noise is composed of multiple paths, then the transfer path analysis test of the vehicle was carried out, and the transfer function and operational data at speed range started from 20 to 100 km/h were obtained. On the basis of the transfer path analysis results and the above principle, the friction damper on the body side of the nearside mount is improved by combination of the experimental transfer path analysis and the final measurements. The results indicate that a significant reduction for the A-weighted sound pressure level of the interior noise has been gained when the frictional damper was added to conventional mount.
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Li, Zheng Feng, and Lian Zhou Gao. "Study on WSN Localization Algorithm and Simulation Model for Intelligent Transportation System." Applied Mechanics and Materials 548-549 (April 2014): 1407–14. http://dx.doi.org/10.4028/www.scientific.net/amm.548-549.1407.
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This paper conducts research on the algorithm to improve the location of Wireless Sensor Network (WSN) in Intelligent Transportation System (ITS). The localization algorithm introduced an improved RSSI vehicle localization algorithm based on multi-path effect and Gaussian white noise. The localization results under different values of Gaussian white noise and different density of beacon nodes are analyzes, and Kalman filtering algorithm is introduced to reduce the influence of signal noise. Finally, a simulation model of ITS is developed to test the algorithm based on mixed noise and Kalman filtering algorithm, which is used to simulate the localization of real vehicles. The simulation shows the algorithm has effect to improve location accuracy and to application
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Gao, Lian Zhou. "Study on WSN Localization Algorithm and Simulation Model for Intelligent Transportation System." Applied Mechanics and Materials 539 (July 2014): 867–73. http://dx.doi.org/10.4028/www.scientific.net/amm.539.867.
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This paper conducts research on the algorithm to improve the location of Wireless Sensor Network (WSN) in Intelligent Transportation System (ITS). The localization algorithm introduced an improved RSSI vehicle localization algorithm based on multi-path effect and Gaussian white noise. The localization results under different values of Gaussian white noise and different density of beacon nodes are analyzes, and Kalman filtering algorithm is introduced to reduce the influence of signal noise. Finally, a simulation model of ITS is developed to test the algorithm based on mixed noise and Kalman filtering algorithm, which is used to simulate the localization of real vehicles. The simulation shows the algorithm has effect to improve location accuracy and to application
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Li, Muxiao, Ziwei Zhu, Tiesong Deng, and Xiaozhen Sheng. "An investigation into high-speed train interior noise with operational transfer path analysis method." Railway Engineering Science 29, no. 1 (February 26, 2021): 1–14. http://dx.doi.org/10.1007/s40534-021-00235-0.
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AbstractPassengers' demands for riding comfort have been getting higher and higher as the high-speed railway develops. Scientific methods to analyze the interior noise of the high-speed train are needed and the operational transfer path analysis (OTPA) method provides a theoretical basis and guidance for the noise control of the train and overcomes the shortcomings of the traditional method, which has high test efficiency and can be carried out during the working state of the targeted machine. The OTPA model is established from the aspects of "path reference point-target point" and "sound source reference point-target point". As for the mechanism of the noise transmission path, an assumption is made that the direct sound propagation is ignored, and the symmetric sound source and the symmetric path are merged. Using the operational test data and the OTPA method, combined with the results of spherical array sound source identification, the path contribution and sound source contribution of the interior noise are analyzed, respectively, from aspects of the total value and spectrum. The results show that the OTPA conforms to the calculation results of the spherical array sound source identification. At low speed, the contribution of the floor path and the contribution of the bogie sources are dominant. When the speed is greater than 300 km/h, the contribution of the roof path is dominant. Moreover, for the carriage with a pantograph, the lifted pantograph is an obvious source. The noise from the exterior sources of the train transfer into the interior mainly through the form of structural excitation, and the contribution of air excitation is non-significant. Certain analyses of train parts provide guides for the interior noise control.
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Lovstedt, Stephan P., Jared K. Thomas, Scott D. Sommerfeldt, and Jonathan D. Blotter. "Genetic Algorithm Applied to the Eigenvalue Equalization Filtered-x LMS Algorithm (EE-FXLMS)." Advances in Acoustics and Vibration 2008 (May 8, 2008): 1–12. http://dx.doi.org/10.1155/2008/791050.
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The FXLMS algorithm, used extensively in active noise control (ANC), exhibits frequency-dependent convergence behavior. This leads to degraded performance for time-varying tonal noise and noise with multiple stationary tones. Previous work by the authors proposed the eigenvalue equalization filtered-x least mean squares (EE-FXLMS) algorithm. For that algorithm, magnitude coefficients of the secondary path transfer function are modified to decrease variation in the eigenvalues of the filtered-x autocorrelation matrix, while preserving the phase, giving faster convergence and increasing overall attenuation. This paper revisits the EE-FXLMS algorithm, using a genetic algorithm to find magnitude coefficients that give the least variation in eigenvalues. This method overcomes some of the problems with implementing the EE-FXLMS algorithm arising from finite resolution of sampled systems. Experimental control results using the original secondary path model, and a modified secondary path model for both the previous implementation of EE-FXLMS and the genetic algorithm implementation are compared.
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Han, X., Y.-J. Guo, Y.-E. Zhao, and Z.-Q. Lin. "The application of power-based transfer path analysis to passenger car structure-borne noise." Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering 222, no. 11 (November 1, 2008): 2011–23. http://dx.doi.org/10.1243/09544070jauto750.
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Structure-borne noise in a passenger car is usually transmitted through multiple and/or multi-dimensional paths. Therefore, identification and control of these transfer paths are effective measures for noise reduction. A power-based transfer path analysis methodology is proposed for this purpose. First, the power flow of each transfer path is estimated with an equivalent-uncoupled-system method based on linear network theory and the Thevenin equivalent theorem. Next, the correlation between the power flow of each transfer path and the sound pressure in the passenger compartment is established; then the contribution of each transfer path is ranked; meanwhile the dominant paths and their key parameters are identified through the equations of power flow calculation. Finally, these key parameters can be analysed and then improved to reduce the structure-borne noise. An illustration of this methodology is given with a passenger car model containing a power plant, three mounts, a compliant car body, and an enclosed acoustic cavity. It is demonstrated that the methodology is effective to analyse and control the structure-borne noise transfer paths.
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Freidlin, Mark, and Ruth Pfeiffer. "A model discrimination method for processes with different memory structure." Mathematical Problems in Engineering 5, no. 1 (1999): 33–54. http://dx.doi.org/10.1155/s1024123x99000988.
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In this paper we develop a test for determining whether the observed sample path comes from a system with hysteresis perturbed by noise, or if it arises from a system governed by an ordinary differential equation with the same noise. A large sample size test is constructed, which is appropriate in many practical situations. Two models are considered as alternatives to the hysteresis model. An asymptotic expression for the cutoff point of the test is found using a version of the central limit theorem.
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Gong, Hui, Peng Wang, Cui Ni, and Nuo Cheng. "Efficient Path Planning for Mobile Robot Based on Deep Deterministic Policy Gradient." Sensors 22, no. 9 (May 8, 2022): 3579. http://dx.doi.org/10.3390/s22093579.
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When a traditional Deep Deterministic Policy Gradient (DDPG) algorithm is used in mobile robot path planning, due to the limited observable environment of mobile robots, the training efficiency of the path planning model is low, and the convergence speed is slow. In this paper, Long Short-Term Memory (LSTM) is introduced into the DDPG network, the former and current states of the mobile robot are combined to determine the actions of the robot, and a Batch Norm layer is added after each layer of the Actor network. At the same time, the reward function is optimized to guide the mobile robot to move faster towards the target point. In order to improve the learning efficiency, different normalization methods are used to normalize the distance and angle between the mobile robot and the target point, which are used as the input of the DDPG network model. When the model outputs the next action of the mobile robot, mixed noise composed of Gaussian noise and Ornstein–Uhlenbeck (OU) noise is added. Finally, the simulation environment built by a ROS system and a Gazebo platform is used for experiments. The results show that the proposed algorithm can accelerate the convergence speed of DDPG, improve the generalization ability of the path planning model and improve the efficiency and success rate of mobile robot path planning.
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Gunda, R., S. Gau, and C. Dohrmann. "Analytical Model of Tire Cavity Resonance and Coupled Tire/Cavity Modal Model." Tire Science and Technology 28, no. 1 (January 1, 2000): 33–49. http://dx.doi.org/10.2346/1.2135990.
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Abstract The acoustic resonance of the air cavity in the tire/wheel assembly may be a contributor to vehicle interior noise through the structure-borne noise transmission path. This problem has been examined in the past using approximate closed form solutions (based on plane wave theory for a two-tube model) and numerically, using FEA. The coupling between the cavity resonance and structural resonance of the wheel may result in higher levels of interior noise as noted previously. The two primary goals of this paper are (1) to develop simple analytical models to gain fundamental understanding of some observed phenomena and for a quick estimation of cavity resonance frequency to assist in the design process, and (2) to develop tire modal models incorporating the acoustic cavity to predict coupled system natural frequencies and response. An improved analytical model for accurate calculation of acoustic cavity resonance frequencies of a static, unloaded tire is developed using variational principles. The sensitivities of the cavity resonance frequencies to tire width and aspect ratio are examined. For the case of a loaded tire, an improved analytical formulation based on plane wave propagation (for linearly varying cross-sectional area) is developed. Deformed structure geometry from FEA is used as input to the analytical model. The FEA-based methodology used in the tire/cavity coupling analysis is as follows: The tire structural modes are calculated, ignoring the effect of the acoustic cavity. The tire cavity modes are calculated using deformed cavity geometry only. Next, the structural/acoustic coupling matrix is calculated. Finally, a coupled cavity-structure modal model is generated from modal mass and stiffness of the tire/wheel assembly, the cavity modal matrices, and the coupling matrix. This process is an improvement over conventional tire modal models, which only include structural modes.
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Lee, Young-Sup, Yunseon Choi, and Jeakwan Kim. "Length Variation Effect of the Impulse Response Model of a Secondary Path in Embedded Control." Journal of Sensors 2016 (2016): 1–7. http://dx.doi.org/10.1155/2016/8270121.
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This study presents theoretical and experimental investigation on the length variation effect of the impulse response function (IRF) for the secondary path model in active noise control using an embedded control board. A narrowband sweep noise was the disturbance for control in a duct with the length of 1800 mm. The IRF model incorporated into an adaptive feedforward filtered-x LMS (FxLMS) algorithm was then analyzed in the variation of its length in terms of the mean square error, computation complexity, stability requirement, and attenuation performance before and after control. The FxLMS algorithm with various IRF lengths was implemented in a dSPACE DS1104 embedded control board for the real-time control. Finally the most reasonable IRF length, considering the computation complexity and performance, can be determined through the systematic investigation. The results in this study can be used for practical active noise control systems.
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Huang, Quanzhen, Suxia Chen, Mingming Huang, and Zhuangzhi Guo. "Adaptive Active Noise Suppression Using Multiple Model Switching Strategy." Shock and Vibration 2017 (2017): 1–6. http://dx.doi.org/10.1155/2017/7289076.
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Active noise suppression for applications where the system response varies with time is a difficult problem. The computation burden for the existing control algorithms with online identification is heavy and easy to cause control system instability. A new active noise control algorithm is proposed in this paper by employing multiple model switching strategy for secondary path varying. The computation is significantly reduced. Firstly, a noise control system modeling method is proposed for duct-like applications. Then a multiple model adaptive control algorithm is proposed with a new multiple model switching strategy based on filter-u least mean square (FULMS) algorithm. Finally, the proposed algorithm was implemented on Texas Instruments digital signal processor (DSP) TMS320F28335 and real time experiments were done to test the proposed algorithm and FULMS algorithm with online identification. Experimental verification tests show that the proposed algorithm is effective with good noise suppression performance.
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TAKAHASHI, Eisuke, and Manabu YAMADA. "113 Adaptive Active Noise Control without Identification of Secondary Path Dynamics(Model Order reduction of an Acoustic Path)." Proceedings of Conference of Tokai Branch 2012.61 (2012): _113–1_—_113–2_. http://dx.doi.org/10.1299/jsmetokai.2012.61._113-1_.
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Mohamed Hadi Habaebi, Ahmad Shahmi Mod Rofi, Md Rafiqul Islam, and Ahmed Basahel. "ANN-based LoRaWAN Channel Propagation Model." International Journal of Interactive Mobile Technologies (iJIM) 16, no. 11 (June 7, 2022): 91–106. http://dx.doi.org/10.3991/ijim.v16i11.30095.
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LoRaWAN wireless communication channels are often impacted by noise and interference over long-range causing loss of a received signal. One of the main drawbacks of using existing propagation models is less accurate as these models in designing the communication link are tailored to simplify the estimation. In this paper, an artificial intelligent real time path loss model is proposed. It is capable of processing complex variables over a short period of time. Providing it with enough data, the model is able to learn channel behavior and predict the path loss accurately. Results of the model are benchmarked against classical statistical curve fitting models where RMSE values are also compared and indicating that the artificial intelligent model has better accurate prediction.
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Phaiboon, Supachai, and Supanuch Seesaiprai. "Path Loss through Pine Forest around Beach for Wireless Sea Wave Energy Sensor Network." Advanced Materials Research 433-440 (January 2012): 3954–58. http://dx.doi.org/10.4028/www.scientific.net/amr.433-440.3954.
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This paper presents an empirical path loss model through forest for measuring sea wave energy using 2.4 GHz wireless sensor network (WSN). The empirical path loss model was determined from measurement campaign by using 18 dBm transmitter and the receivers with a low noise amplify. The conventional path loss models for forest environments were carried out such as Weissberger, ITU-R, COST 235 and Torrico models. From the results it is found that the proposed model provides a good agreement and is used for planning WSN.
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Dovbnya, Vitaly G., and Dmitry S. Koptev. "MATHEMATICAL MODEL OF THE RECEIVING PATH OF DIGITAL COMMUNICATION LINES." T-Comm 15, no. 5 (2021): 52–57. http://dx.doi.org/10.36724/2072-8735-2021-15-5-52-57.
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Modern trends in the development of digital communication lines of fixed information transmission services, as well as the characteristics of continuous channels today determine the noise immunity of radio receiving systems. The main directions of its increase in terms of the radio receiving device as a whole and the demodulator device in particular are as follows: reducing the frequency and nonlinear distortions of the signal in the linear path, increasing the stability and purity of the spectral line of oscillations of local oscillators, increasing the selectivity for the mirror and combination channels of reception, compensation for intersymbol and cross – polarization interference, improving the functioning of the automatic gain control device (reducing static and dynamic errors), improving the quality of the functioning of the carrier wave recovery device and the clock synchronization device. Taking into account all of the above factors in order to increase the overall noise immunity of a digital communication line is a very difficult and urgent task, the solution of which must begin with the development of a mathematical model of a continuous digital communication line channel. This article discusses the radio receiving path of a digital communication line in an urban environment. The obtained analytical expressions are aimed at interpreting the processes of converting digital signals in the structural elements of radio receiving systems. The originality of the mathematical model developed in the article lies in the fact that it additionally, in comparison with similar models, takes into account the following number of factors: frequency instability and phase fluctuations of oscillations of the local oscillator synthesizer, dynamic and static errors in the operation of automatic gain control devices, carrier vibration recovery devices and devices clock synchronization of radio receiving systems of digital signals.
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Giladi, Ran, and Eliav Menachi. "Validating Aircraft Noise Models." Proceedings 59, no. 1 (December 3, 2020): 12. http://dx.doi.org/10.3390/proceedings2020059012.
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Aircraft noise, especially at takeoffs and landings, became a major environmental nuisance and a health hazard for the population around metropolitan airports. In the battle for a better quality of life, wellbeing, and health, aircraft noise models are essential for noise abatement, control, enforcement, evaluation, policy-making, and shaping the entire aviation industry. Aircraft noise models calculate noise and exposure levels based on aircraft types, engines and airframes, aircraft flight paths, environment factors, and more. Validating the aircraft noise model is a mandatory step towards the model credibility, especially when these models play such a key role with a huge impact on society, economy, and public health. Yet, no validation procedure was offered, and it turns out to be a challenging task. The actual, measured, aircraft noise level is known to be subject to statistical variation, even for the same aircraft type at the same situation and flight phase, executing the same flight procedure, with similar environmental factors and at the same place. This study tries to validate the FAA’s AEDT aircraft noise model, by trying to correlate the specific flight path of an aircraft with its measured noise level. The results show that the AEDT noise model underestimates the actual noise level, and four validation steps should be performed to correct or tune aircraft noise databases and flight profiles.
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WANG, Dianwei, Wang LIU, Jie FANG, and Zhijie XU. "Enhancement algorithm of low illumination image for UAV images inspired by biological vision." Xibei Gongye Daxue Xuebao/Journal of Northwestern Polytechnical University 41, no. 1 (February 2023): 144–52. http://dx.doi.org/10.1051/jnwpu/20234110144.
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To address the issue of low brightness, high noise and obscure details of UAV aerial low-light images, this paper proposes an UAV aerial low-light image enhancement algorithm based on dual-path inspired by the dual-path model in human vision system. Firstly, a U-Net network based on residual element is constructed to decompose UAV aerial low-light image into structural path and detail path. Then, an improved generative adversarial network (GAN) is proposed to enhance the structural path, and edge enhancement module is added to enhance the edge information of the image. Secondly, the noise suppression strategy is adopted in detail path to reduce the influence of noise on image. Finally, the output of the two paths is fused to obtain the enhanced image. The experimental results show that the proposed algorithm visually improves the brightness and detail information of the image, and the objective evaluation index is better than the other comparison algorithms. In addition, this paper also verifies the influence of the proposed algorithm on the target detection algorithm under low illumination conditions, and the experimental results show that the proposed algorithm can effectively improve the performance of the target detection algorithm.
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Yan, Tingting, Shengbo Hu, and Jinrong Mo. "Path Formation Time in the Noise-Limited Fractionated Spacecraft Network with FDMA." International Journal of Aerospace Engineering 2018 (October 2, 2018): 1–12. http://dx.doi.org/10.1155/2018/9124132.
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Connectivity and path formation time are very important for the design and optimization in fractionated spacecraft network. Taking frequency division multiple access (FDMA) with subcarrier binary phase-shift keying (BPSK) modulation as an example, this paper focuses on the issues of constraint to orbital elements and path formation time for the noise-limited fractionated spacecraft network percolating. First, based on the proposed evolution of the dynamic topology graph in the fractionated spacecraft network, we prove the constraint condition of orbital elements for noise-limited fractionated spacecraft network percolating, and the definition of path formation time is provided and the mobility model is established. Next, we study the relationship between first docking time and spatial initial distribution and the relationship between first separating time and spatial initial distribution. These relationships provide an important basis for the orbit design in the fractionated spacecraft network. Finally, the numerical results show that the network topology for fractionated spacecraft is time-varying and dynamic. The path formation time and hop length scale linearly with path length within each orbital hyperperiod and change periodically. Besides, the time constant gradually tends to a stable value with path formation time increasing, that is, path length. These results powerfully support percolation theory further under the environment of the noise-limited fractionated spacecraft network.
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Zhang, Qi-Zhi, and Woon-Seng Gan. "A model predictive algorithm for active noise control with online secondary path modelling." Journal of Sound and Vibration 270, no. 4-5 (March 2004): 1056–66. http://dx.doi.org/10.1016/s0022-460x(03)00516-9.
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YOKOTA, Kazuya, Yosuke KOBA, Satoshi ISHIKAWA, and Shinya KIJIMOTO. "704 Active Noise Control Following Moving Evaluation Point with Appropriate Secondary Path Model." Proceedings of Conference of Kyushu Branch 2015.68 (2015): 265–66. http://dx.doi.org/10.1299/jsmekyushu.2015.68.265.
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Gorai, A. K., S. Maity, and A. K. Pal. "Development of the Path Model in Road Traffic Noise Annoyance of Dhanbad Township." Noise & Vibration Worldwide 38, no. 3 (March 2007): 17–22. http://dx.doi.org/10.1260/095745607780797649.
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BOTELHO, LUIZ C. L. "TURBULENT COLD PLASMA: AN EXACTLY PATH INTEGRAL SOLUTION IN A ZERO DIMENSIONAL MODEL AND ITS GENERALIZATIONS TO THE THREE-DIMENSIONAL-CASE." International Journal of Modern Physics B 13, no. 13 (May 30, 1999): 1663–74. http://dx.doi.org/10.1142/s0217979299001648.
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We write path integrals exact solutions for a 0-dimensional noise (turbulent) force equation for an electronic plasma. We obtain that the equilibrium limit of the plasma tensor magneto conductivity coincides with the classical non-turbulent result in our 0-dimensional proposed model. Additionally, we show the usefulness of our reduced model by writing exact path integrals solutions for the probabilistic turbulent plasma occupation times. Finally, we point out three-dimensional generalizations of our path integral studies in two appendix.