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.
Results
Showing 1 to 20 of 124 for “"Noise Control"”.
-
Entertainment noise control in Algeria
These last ten years, in Algeria noise pollution has become an environmental issue where people are exposed to unacceptable levels of noise. The main noise source is from traffic, from neighbourhood and domestic noise particularly {entertainment premises known as wedding halls}. Other significant …
-
Aircraft interior acoustic noise control
… materials are best suited for internal aircraft noise reduction. An impedance tube with dimensions of a scaled aircraft was constructed and evaluated, and eleven materials were tested and compared based on their noise reduction properties, weight, and thickness. Polyvinylidene Fluoride was tested …
-
Passive Noise Control in Incubators
… Due to operating equipment and environmental noise, the sound level that is perceived by the developing newborn can cause both short and long term hearing loss as well as psychological damage [1].This thesis presents a study on how passive noise control devices can be used to reduce SPL levels …
-
Multiple Reference Active Noise Control
The major application of active noise control (ANC) has been focused on using a single reference signal; the work on multiple reference ANC is very scarce. Here, the behavior of multiple reference ANC is analyzed in both the frequency and time domain, and the coherence functions are provided to …
-
Active noise control in a luxury vehicle
Structure-borne road noise is a critical sound attribute for the overall Noise Vibration& Harshness (NVH) performance of modern luxury vehicles. Currentpassive NVH solutions require structural design modifications, in order to controllow frequency sources that cause structure-borne noise. Active …
-
Jet Noise Control by Adjoint-Based Optimization
… a way that its solution can be used to optimize control actuation in order to reduce the noise radiated by a randomly excited two-dimensional mixing layer, which serves as near-nozzle model of a jet. The initial-vorticity-thickness Reynolds number is 500, and the free stream Mach numbers are 0.9 …
-
Active noise control using glow discharge plasma panels
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 2001.
-
Piezoceramic Actuated Transducers for Interior Acoustic Noise Control
… is that passive methods currently used for noise suppression do not exhibit significant energy dissipation at low frequencies. This motivates the use of active noise control. Using active noise control for frequencies below 200 to 300 Hz in addition to the passive control means has potential …
-
High-pressure compliant syntactic foam for hydraulic noise control
… within a hydraulic system, commonly known as noise, create problems, such as leaks and breakout noise, within the system and necessitate treatment. Prior work has demonstrated the effectiveness of a flow-through expansion chamber with a syntactic foam liner; the device is known as a …
-
Theory and Design of Spatial Active Noise Control Systems
The concept of spatial active noise control is to use a number of loudspeakers to generate anti-noise sound waves, which would cancel the undesired acoustic noise over a spatial region. The acoustic noise hazards that exist in a variety of situations provide many potential applications for spatial …
-
Theory and Design of Spatial Active Noise Control Systems
The concept of spatial active noise control is to use a number of loudspeakers to generate anti-noise sound waves, which would cancel the undesired acoustic noise over a spatial region. The acoustic noise hazards that exist in a variety of situations provide many potential applications for spatial …
-
A Study of Smart Foam for Noise Control Applications
Smart foam is a composite noise control treatment that consists of a distributed piezoelectric actuator, known as polyvinylidene fluoride (PVDF), embedded within a layer of partially-reticulated polyurethane foam. The principal function of smart foam is to yield broadband sound attenuation. Passive …
-
Acoustic prediction and noise control of a refrigeration compressor
In this study, the prediction and control of the acoustic radiation from a Bristol H25A refrigeration compressor are investigated. For the acoustic prediction, a modal decomposition approach is used. To this end, a boundary element model of the shell is created, and it is used to compute the modal …
-
Laser Doppler Vibrometry Based Remote Sensing for Active Noise Control
Demands for active noise control/cancellation (ANC) to provide a quiet environment have grown significantly over the past few decades. Notably, many ANC headphones and earphones have emerged and gained much success in the market due to their excellent performance and robustness. There are also …
-
Acoustical characterization and parameter optimization of polymeric noise control materials
The sound transmission loss (STL) characteristics of polymer-based materials are considered. Analytical models that predict, characterize and optimize the STL of polymeric materials, with respect to physical parameters that affect performance, are developed for single layer panel configuration and …
-
Optimization of Active Noise Control for Small Axial Cooling Fans
Previous work has shown that active noise control is a feasible solution to attenuate tonal noise radiated by small axial cooling fans, such as those found in desktop computers. One such control system reduced noise levels of a baffled 80-mm fan in the free field with four small loudspeakers …
-
Microjet based noise control of supersonic jets on carrier decks
The effectiveness of ground plane water microjet control on the noise generated by a supersonic, ideally expanded, Mach 1.5, impinging jet was determined. Using a converging-diverging nozzle with a design Mach number of 1.5, the jet was operated at temperatures ranging from 60 to 1700°F. Six …
-
Active noise control of supersonic impinging jet using pulsed microjets
This thesis concerns an active noise control of supersonic impinging jet flow using unsteady microjet injection. Supersonic impinging jet involves several problems such as lift loss, ground erosion, significant noise pollution, and sonic fatigue, all of which are dominated by impinging tones mainly …
-
A Hierarchical Noise Control System Using Adaptable Tuned Vibration Absorbers
A novel noise control system is developed using adaptable tuned vibration absorbers (ATVA) to interact with a vibrating host structure in such a way as to reduce radiated acoustic energy. ATVA's are single-degree-of-freedom resonant devices that can change their resonant frequency and damping over …
-
Acoustic Characterization and Preliminary Noise Control of Pneumatic Percussion Tools
… machines in the construction industry generating noise levels above 110 dBA which are well beyond the permissible exposure limit (PEL) of 85 dBA. This work presents a comprehensive methodology for the acoustic characterization and noise source identification of these percussion tools. The …
Page 1 of 7