Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 21 for “"Interior Noise"”.
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Heterogeneous (HG) Blankets for Improved Aircraft Interior Noise Reduction
… of the HG blankets can result in broadband noise reduction below 500Hz with less than 10% added mass.
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Attenuation of Turbulent Boundary Layer Induced Interior Noise Using Integrated Smart Foam Elements
… attenuation of turbulent boundary layer induced interior noise. The treatment consisted of several Smart Foam actuators each having a reference and error sensor along with a feed forward, filtered-x controller. Studies were performed to determine if the use of multiple instances of single input, …
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Structure-Borne Vehicle Interior Noise Estimation Using Accelerometer Based Intelligent Tires in Passenger Vehicles
… are becoming quieter than ever before. But noise levels remain a significant concern for both passengers and automotive manufacturers. The vehicle's interior noise can affect the overall driving experience and even the safety of the driver and the passengers. The two main sources of vehicle …
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Active control of interior noise using piezoelectric actuators in a large-scale composite fuselage model
Active control of single-frequency interior noise in a realistic composite aircraft fuselage is experimentally studied. The control inputs are due to piezoelectric actuators bonded to the cylinder wall while error information from the interior acoustic field is sensed by microphones. A preliminary …
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Characterization of Structure-Borne Tire Noise Using Virtual Sensing
… have been made to the vehicle (reduced engine noise, reducedaerodynamic related NVH), have resulted in tire road noise as the dominant source of thevehicle interior noise. Generally, vehicle interior noise has two main sources, 1) travellinglow frequency excitation below 800 Hz from road …
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Active structural acoustic control of aircraft interior flow noise via the use of active trim panels
Modem jet aircraft interior noise can be categorized into two main types: tonal noise caused by engine imbalance or blade passage, and mid frequency broadband noise resulting from turbulent flow. This project addresses aircraft interior flow noise caused by a flow separation over the crown of the …
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Utilizing Distributed Vibration Absorbers to Reduce Noise Transmission Through the Windshield of a Cessna 150
High levels of noise have historically been present in the interior of aircrafts. This causes passenger, pilot, and other aircraft employee fatigue as well as speech interference and discomfort issues. In general aviation aircraft, little has been done to reduce the noise in the interior of …
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Active control of an automobile suspension system for reduction of vibration and noise
A new method for controlling road noise transmitted through the suspension system of an automobile was developed, using a Lincoln LS automobile as the target vehicle. In this vehicle, road surface roughness generates vibrations that are transmitted into the automobile primary through a single …
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Intelligibility of synthesized voice messages in commercial truck cab noise for normal-hearing and hearing-impaired listeners
… of synthesized speech under a variety of noise conditions for both hearing-impaired and normal-hearing subjects. Modified Rhyme Test stimuli were used to determine intelligibility in four speech-to-noise (S/N) ratios (0, 5, 10, and 15 dB), and three noise types, consisting of …
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Smart double panel with decentralised active damping units for the control of sound transmission
… part of the thesis a survey of aircraft interior noise is given, and stateof- the-art passive and active noise control methods are presented. In Chapter two the mathematical model for the theoretical analysis of the smart double panel is formulated and a parametric study of passive sound …
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An investigation of the structurally induced acoustic field in a car passenger compartment
… and characteristics of structurally induced interior noise in cars in relation to the boom problem is discussed and the relevant theory developed. The work is concerned with structural excitation of the air within the passenger compartment associated with the second order component of the …
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Decentralised velocity feedback control for thin homogeneous and lightweight sandwich panels
… which could cause problems with vehicle interior noise. The aim of this work is to assess the performance of decentralised velocity feedback control on lightweight sandwich panels.<br/>The first part of this thesis presents the theoretical model used to predict the structural response, …
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Structure-acoustic analysis; finite element modelling and reduction methods
… engineering problems, for example, studying the interior noise in a vehicle or the sound transmission loss in a wall between two dwellings. The geometrical properties of the studied system and the frequency limit of interest for the analysis determine the size of the system of equations to be …
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System Identification and Optimization Methodologies for Active Structural Acoustic Control of Aircraft Cabin Noise
… (ASAC) has shown much promise for reducing interior cabin noise in aircraft by applying control forces directly to the fuselage structure. Optimal positioning of force actuators for ASAC presents a challenging problem however, because a detailed knowledge of the structural-acoustic coupling …
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A Coupled Tire Structure-Acoustic Cavity Model
… cabin and may be responsible for significant interior noise. The tire acoustic cavity is excited by the road surface through the contact patch on the rotating tire. The effect of the cavity resonance is that results in significant forces developed at the vehicle's spindle, which in turn drives …
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Vibration Modeling and Experimental Analysis of a Locomotive Cab
This study evaluates noise and vibrations in a heavy freight locomotive cab, and provides several measures for providing more comfort to the crew. A full-scale production cab and sill structure is used to provide the results. The cab is setup in a controlled laboratory environment in a manner …
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MODELING AND DESIGN OF A SMART DOUBLE-PANEL SYSTEM FOR THE CONTROL OF SOUND TRANSMISSION INTO AIRCRAFT CABIN
Nowadays, the level of interior cabin noise in modern aircraft has been reduced significantly compared with noise levels in the past because the double-panel design of aircraft sidewall systems has been much optimized. Furthermore, new composite materials are now used in the design of trim panels …
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Acoustic Devices for the Active & Passive Control of Sound in a Payload Compartment
… Helmholtz resonators and loudspeakers used for noise control in rocket payload compartments are developed. Second, active control using a hybrid control system (with structural and acoustic actuators) was tested experimentally. Due to the weight limitations for this application, Helmholtz …
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A Principal Component Algorithm for Feedforward Active Noise and Vibration Control
… of the method was demonstrated in real-time noise control experiments involving 48 microphones and 12 control actuators mounted on a closed cylindrical shell. Convergence of the PC-LMS algorithm was more stable than the filtered-x LMS algorithm. In addition, the PC-LMS controller produced …
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