Noise Control Solutions for Diesel Generator Sets

A persistent challenge for Oman's energy infrastructure was the deafening rumble of diesel generators. The Silent Generator Project addressed this challenge, developing advanced generators that deliver power quietly and efficiently. Diesel generators have historically been notorious for being noisy and vibrational, making them unsuitable for sensitive environments. To dramatically reduce noise levels, the project utilized innovative materials and design modifications to ensure reliable and quiet electricity for various applications. In all directions, the project advanced the knowledge of noise reduction through rigorous testing and meticulous integration of insulators and mufflers. As a result, quieter, more sustainable energy production is on the way, marking a major advance in silent generator technology. Furthermore, the Silent Generator Project lays the foundation for more efficient and environmentally friendly diesel generator technologies in the future. As a result of this research, a new standard for quieter, greener energy generation is established, demonstrating the critical role noise reduction plays in energy generation. Additionally, this work also suggests future diesel generator technologies that are more efficient and environmentally friendly. As a result of this research, a new standard for quieter, greener energy generation is set, demonstrating the critical role noise reduction plays in energy generation.

Flower Pollination Heuristics for Nonlinear Active Noise Control Systems

In this paper,a novel design of the flower pollination algorithm is presented for model identification problems in nonlinear active noise control systems.The recently introduced flower pollination based heuristics is implemented to minimize the mean squared error based merit/cost function representing the scenarios of active noise control system with linear/nonlinear and primary/secondary paths based on the sinusoidal signal,random and complex random signals as noise interferences.The flower pollination heuristics based active noise controllers are formulated through exploitation of nonlinear filtering with Volterra series.The comparative study on statistical observations in terms of accuracy,convergence and complexity measures demonstrates that the proposed meta-heuristic of flower pollination algorithm is reliable,accurate,stable as well as robust for active noise control system.The accuracy of the proposed nature inspired computing of flower pollination is in good agreement with the state of the art counterpart solvers based on variants of genetic algorithms,particle swarm optimization,backtracking search optimization algorithm,fireworks optimization algorithm along with their memetic combination with local search methodologies.Moreover,the central tendency and variation based statistical indices further validate the consistency and reliability of the proposed scheme mimic the mathematical model for the process of flower pollination systems.

Weighing and Prioritizing Noise Control Methods Using the Delphi Technique and the Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS) in an Iranian Tire Manufacturing Factory

Undoubtedly,noise has become a major hazardous issue in today’s industrial world,with a lot of people suffering from exposure to excessive noise in their work environments.This study was conducted to weigh and prioritize noise control methods in an Iranian tire manufacturing complex in Iran.The Delphi method and the Technique for Order Preference by Similarity and an Ideal Solution(TOPSIS)were utilized for this purpose.This cross-sectional,descriptive study was conducted in the baking hall of an Iranian tire manufacturing factory in 2016.To weigh and prioritize noise control methods,Analytic Hierarchy Process(AHP)and TOPSIS were applied.In total,4 criteria and 8 alternatives were examined.An AHP and TOPSIS questionnaire was then designed to prioritize noise control methods in the light of the objectives,criteria,and alternatives.Then,the collected data were fed into Expert Choise.V.11 and Excel and data analysis was carried out using TOPSIS.The results of data analysis indicated that the inconsistency rate in all the cases was smaller than 10%,hence the consistency of the responses was verified.According to the TOPSIS results and experts’opinions about the criteria,implementation and maintenance cost(with a weight of 0.481)and method effectiveness and efficiency(with a weight of 0.046)had the highest and lowest priority respectively.Based on the weights TOPSIS,the appropriate methods for controlling noise in tire manufacturing are designing and manufacturing silencer,requiring people in charge to quickly fix the leaks and change baking press washers on time.

Evaluation of Environmental Sound Pressure Level,Drawing of Noise-Isosonic Map Using Surfer V.19,and Prioritization of Engineering Noise Control Methods Using the Analytic Hierarchy Process(AHP):A Field Study in CGS Stations

Noise pollution is one of the most significant harmful physical factors in the industrial and occupational environments.Due to the high costs of exposure to excessive noise;continuous sound evaluation,propose and implement noise control plans in occupational environments is necessary.Thus,the present study aimed to review environmental sound measurements,drawing of noise maps,and prioritizing the engineering noise control methods using the Analytic Hierarchy Process(AHP).This study was a descriptive-analytical study that aimed to assess occupational noises and present a control plan in the City Gas Stations(CGSs)of Kerman,Iran in 2021.The present study was done in two phases.In the first phase,six CGSs were investigated to measure and evaluate the noise.In addition,the noise map of a CGS was drawn using the Surfer software.Finally,the AHP was used in the second phase of the research to prioritize the control measures.In this phase,four criteria and ten alternatives were identified.According to first phase results,the sound pressure level(SPL)of the stations varied from 76 to 98 dBA.Besides,the majority of the studied stations had a sound level higher than 85 dBA(danger zone).The second phase of the study showed that out of the four evaluated criteria,the executability criterion had the highest impact and the cost criterion had the lowest impact on the selection of control measures with a weight of 0.587 and 0.052,respectively.Based on the results of prioritization of the alternatives,using a silenced regulator(weight of 0.223)and increasing the thickness of the tube(weight of 0.023)had the highest and lowest priorities among the alternatives,respectively.The use of engineering noise control methods such as using silenced regulators was the best way to control the noises of CGSs.Additionally;it is noteworthy that AHP is a practical method for prioritizing alternatives to achieve the most accurate decision-making.The results of AHP can be of great help to health and safety experts and managers in choosing the sound engineering control measures more precisely.

A Hybrid Nonlinear Active Noise Control Method Using Chebyshev Nonlinear Filter

Investigations into active noise control(ANC)technique have been conducted with the aim of effective control of the low-frequency noise.In practice,however,the performance of currently available ANC systems degrades due to the effects of nonlinearity in the primary and secondary paths,primary noise and louder speaker.This paper proposes a hybrid control structure of nonlinear ANC system to control the non-stationary noise produced by the rotating machinery on the nonlinear primary path.A fast version of ensemble empirical mode decomposition is used to decompose the non-stationary primary noise into intrinsic mode functions,which are expanded using the second-order Chebyshev nonlinear filter and then individually controlled.The convergence of the nonlinear ANC system is also discussed.Simulation results demonstrate that proposed method outperforms the FSLMS and VFXLMS algorithms with respect to noise reduction and convergence rate.

Dynamic Active Noise Control of Broadband Noise in Fighter Aircraft Pilot Helmet

This paper presents the development of a dynamic Active Noise Control(ANC)algorithm aimed towards redu-cingthe broadbandnoiseinside the helmet earcups ofafighter aircraftpilot helmet.The dynamicANC involves a Variable Step-Size Griffiths(VSSG)FxLMS algorithm to attenuate noise entering directly through helmet,a LMS based adaptive noise canceller to attenuate noise entering through the pilot microphone,and energy detectors for failure protection and optimized battery power usage.The algorithms are implemented on Texas Instruments’TMS320C6748 processor and are tested in a helmet ANC experimental setup.

Adaptive ANFIS-based filter for active control of sinusoidal primary noise in nonlinear path

Linear active noise control (ANC) system is promising in suppressing broadband and narrowband noise in a linear acoustic site.However,in some situations,the acoustic systems are nonlinear which make the primary noise being nonlinear distortion at the canceling point,and the linear ANC system maybe can not work well for these cases.This paper presents an adaptive network-based fuzzy inference system (ANFIS)-based nonlinear filter for active noise control,which is expected to be successfully applied to situations with nonlinear distortion.In the proposed adaptive control algorithm,the parameters are updated by gradient descent method.In the simulations,the secondary-path FIR model coefficients are estimated in advance by off-line system identification method,and one case for sinusoidal primary noise with nonlinear distortion is presented,which verifies the effectiveness of the proposed system in suppressing sinusoidal noise generated by rotating machines,e.g.,engines in vehicles.

Noise Pollution Reduction through a Novel Optimization Procedure in Passive Control Methods

This paper proposes a novel optimization framework in passive control techniques to reduce noise pollution.The geometries of the structures are represented by Catmull-Clark subdivision surfaces,which are able to build gap-free Computer-Aided Design models and meanwhile tackle the extraordinary points that are commonly encountered in geometricmodelling.The acoustic fields are simulated using the isogeometric boundary elementmethod,and a density-based topology optimization is conducted to optimize distribution of sound-absorbing materials adhered to structural surfaces.The approach enables one to perform acoustic optimization from Computer-Aided Design models directly without needingmeshing and volume parameterization,thereby avoiding the geometric errors and time-consuming preprocessing steps in conventional simulation and optimization methods.The effectiveness of the present method is demonstrated by three dimensional numerical examples.

Motor Vehicle Noise Control in China

In China there are about 10.4 millions motor vehicles and 13.0 millions of motorcycles in use. The growth of vehicle parc has increasingly caused serious traffic noise harmful to environment. In most of urban area the noise level (L50) along sides of main streets usually exceeds 70 dB（A） or 75 dB（A） during daytime, which has aroused much attention of the Chinese government.

Effect of integral squeeze film damper on vibration and noise of spur gear with center-distance error

When the actual installation center distance between a pair of spur gears is greater than the theoretical center distance,backlash increases,leading to increased vibration and noise.The structural parameters of an integral squeeze film damper(ISFD)were designed with the stiffness of rigid support as reference to investigate the effect of an ISFD on the dynamic characteristics of a spur gear transmission system with center-distance installation error.A spur gear test bench with center distance-error was built to investigate the vibration and noise reduction characteristics of ISFD.The experimental results indicate that,compared with a rigid support,the ISFD can reduce vibration by approximately 40%and noise by approximately 5 d B.ISFD can effectively absorb the impact energy caused by an increase of in backlash,which is conducive to the stable operation of the spur gear transmission system.

Application of system identification in a practical active noise control system

Noise pollution has become increasingly severe around the world due to fast urbanization. How to soundproof windows from outside noise is of significant interest for both academia and industry. This paper reports an experimental implementation of normalized minmax active noise control (ANC) algorithm on an open window system, where identifying the model of acoustic sound paths plays a central role. By doing this, traffic noise is attenuated by the ANC system, leading to a relatively quiet indoor environment, while the natural lighting and ventilation functions of a window are remained. Our experiments show that an average of 19 dB(A) noise reduction is achieved.

Prioritizing and Providing Sound Pollution Control Strategies at the CPF of North Azadegan Oilfield Project

Among the harmful occupational factors,noise is the most common exposure in the oil industrial workplaces.The present study aimed to prioritize sound pollution areas in central processing facilities(CPF)of an oil field in order to provide corrective action in the studied industry and similar industries.After reviewing the issued permit to work,job description and noise dosimetry test,the evaluated areas were selected then sound pressure levels in the referenced areas investigated according to ISO 9612–2009(E)next the noise map prepared for all selected areas.For identifying the prioritized areas to implement the control measures NCPI was used.After identifying the first priority area with sound pressure levels greater than 85 dB,the frequency analysis was performed and Isosonic map was prepared by Surfer v10 and AutoCAD 2014.In the last step,in order to provide appropriate corrective action plan,the compatibility of the determined control actions with the production process was examined.The findings of this study indicates that 74%of the aforesaid area has the first priority to perform control measures in the caution zone and the remaining 26%is in the danger zone.In this study it has been demonstrated that implementing control measures for Zone 2 have first priority.The main source of the noise in this zone is fluid(Gas)flow through the piping and HP Gas Compressors.The results of this study shows that using effective factors such as exposure time,sound pressure level and number of exposed persons,can be present suitable model to prioritize noise control.

Poisson-noise weighted filter for time-offlight positron emission tomography

Image reconstruction for list-mode time-of-flight(TOF)positron emission tomography(PET)can be achieved by analytic algorithms.The backprojection filtering(BPF)algorithm is an efficient algorithm for this task.The conventional noise control method for analytic image reconstruction is the use of a stationary lowpass filter,which does not model the Poisson noise properly.This study proposes a nonstationary filter for Poisson noise control.The filter is implemented in the spatial domain in a form similar to convolution.

Assessment and Optimization Strategies of Campus Sound Environment

A good sound environment is essential in creating a harmonious and peaceful campus,improving students’learning outcomes,promoting physical and mental health,and creating a green and healthy campus.This study investigated the impact of new buildings on existing ones by optimizing the spacing between new buildings and the sound insulation structure of building enclosures.The results indicated that building 4 was affected by the noise from new building 1 and its surroundings,with a maximum outdoor daytime noise level reaching 69 dB,and the indoor background noise level in the least favorable classroom was 43.73 dB,less than 45 dB,which was within the acceptable range.It is recommended that the sound insulation design be improved in the planning of new teaching buildings.Besides,the surrounding traffic conditions should be improved,and the usage time of sports facilities should be scheduled appropriately to prevent the noise from sporting activities from affecting the classroom activities.The findings of this study provide valuable references for future architectural acoustics design and campus planning,contributing to the creation of peaceful and comfortable campus environments.

Propagation of acoustic waves in a fluid-filled pipe with periodic elastic Helmholtz resonators

Helmholtz resonators are widely used to reduce noise in a fluid-filled pipe system. It is a challenge to obtain lowfrequency and broadband attenuation with a small sized cavity. In this paper, the propagation of acoustic waves in a fluid-filled pipe system with periodic elastic Helmholtz resonators is studied theoretically. The resonance frequency and sound transmission loss of one unit are analyzed to validate the correctness of simplified acoustic impedance. The band structure of infinite periodic cells and sound transmission loss of finite periodic cells are calculated by the transfer matrix method and finite element software. The effects of several parameters on band gap and sound transmission loss are probed.Further, the negative bulk modulus of periodic cells with elastic Helmholtz resonators is analyzed. Numerical results show that the acoustic propagation properties in the periodic pipe, such as low frequency, broadband sound transmission, can be improved.

Carrier frequency and symbol rate estimation based on cyclic spectrum

Carrier frequency and symbol rate estimation are the main contents of parameter estimation,which is the basis of modulation recognition and further processing of signals especially in non-cooperative communication.With the development of wireless communication,the signal transmission environment has become increasingly bad,causing more difficulties in parameter estimation.It is well known that the signal cycle spectrum is robust to noises and signal parameters are closely related.In practice,it is impossible to calculate the cyclic spectrum of infinite length data signals.When using finite length data to obtain a cycle spectrum,the truncation noise is induced,resulting in interference.It is necessary to overcome the influence of noises in order to improve the detection ability of discrete spectral lines.An improved method of the discrete spectral line extraction algorithm is proposed by reflecting the amplitude advantage of discrete spectral lines through salient features of continuous noises in discrete spectral line neighborhood.

Research on Influence of Damping Material on Structure Performance of Torpedo

Reducing the self-noise and radiated noise of torpedo is an effective way to enhance its detection and concealment capabilities.After discussing the basic principle on noise and vibration control and main noise sources in torpedo,the application of damping treatment for noise and vibration absorption was proposed in this paper.Compared composite materials(damping and metal materials)used as segment joint,their different contributions to the damping performance of base structure were investigated.The results show that the damping material can be used as segment joint effectively in vibration control.Taking cantilever beam as an example,four different damping treatments were compared in natural frequency and damping loss factor,the results show the influences of different damping layer layouts on the structure damping performance,and offer a reference for the torpedo shell design.

A flexible and high-performance bidirectional optical amplifier with all-optical gain control using ASE noise path through multi-port circulators

We report a flexible all-optical gain controlled bidirectional optical amplifier. The device achieves constant gain and low noise figure over a large input power range. Moreover, the device removes Rayleigh backscattered light and amplifier noise.

A Symplectic Based Neural Network Algorithm for Quantum Controls under Uncertainty

Robust quantum control with uncertainty plays a crucial role in practical quantum technologies.This paper presents a method for solving a quantum control problem by combining neural network and symplecticfinite difference methods.The neural network approach provides a framework that is easy to establish and train.At the same time,the symplectic methods possess the norm-preserving property for the quantum system to produce a realistic solution in physics.We construct a general high dimensional quantum optimal control problem to evaluate the proposed method and an approach that combines a neural network with forward Euler’s method.Our analysis and numerical experiments confirm that the neural network-based symplectic method achieves significantly better accuracy and robustness against noises.