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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Asymptotic waveforms in propeller acoustics

Prentice, Philip Ridley January 1993 (has links)
No description available.
2

The aviation noise defends the research of making and feed backing system rationality¡ÐTake common airport of horse of Penghu as an example.

Hsiao, Ting-Ko 19 June 2004 (has links)
Our national commercial and cargo airlines have great revenue because of rapid developed economics. Especially after the open sky policy. Aviation capacity grows very fast. The convenient of air transportation brings booming economics to the general public; however it also brings destructive environment of airport neighborhood, lower the living quality. Under the aircraft noise for a long term would affect people¡¦s life and work seriously, cause people different level of physical and psychological damages. Citizen views the present monitoring operation of aircraft noise and causes serious environmental pollution issues. Although the government studies airside noise improvement and reward system aggressively, the contestation continues for three years. Every individual airport has conflict with close-by residents frequently. The issue of rationality and fairness of the official aircraft noise prevention and airport reward system is important and meet the exigencies of the moment. This study views the past three years document of aircraft noise prevention and airport reward system, refer to varies information of national and international similar system, analysis and study the reasonable standard level of aircraft noise and related regulations for schools, hospitals residents. Further to offering some strategies and methods to improve the aircraft noise prevention and airport reward system.
3

Aircraft noise and child blood pressure

Morrell, Stephen Louis January 2003 (has links)
The purpose of the study was to examine the existence of an association between child blood pressure (BP) and exposure to domestic jet aircraft noise in the context of the construction of a new parallel north-south runway at Sydney (Kingsford-Smith) Airport. The baseline study was commissioned and funded by the Federal Airports Corporation (FAC), with measurements conducted in 1994 and 1995. A follow-up longitudinal component to the study was subsequently commissioned and funded by the FAC in 1997, and measurements conducted in the same year. As the same individuals were measured and re-measured over changing conditions of exposure to aircraft noise, the quasiexperimental nature of the study allowed inferences to be made regarding exposure to aircraft noise and child BP. The main hypotheses for testing were that BP, and within-subject longitudinal changes in BP, are positively related to domestic jet aircraft noise exposure and longitudinal changes in domestic jet aircraft noise exposure respectively. Subsidiary hypotheses tested for evidence of short- and long-term BP adaptation effects where BPs were related to prior changes to aircraft noise exposures. A sample of 75 primary schools within a 20 km radius of Sydney Airport under various noise exposure conditions, both existing and those projected with the advent of the new runway, participated in the study. The baseline cohort comprised 1,230 Year 3/4 children attending the schools in 1994 and 1995, and the follow-up participants comprised 628 of the original baseline sample re-measured in 1997. Study participants were enrolled by active parental consent. The baseline response rate was approximately 40% of children in the participating schools. Systolic (SBP) and diastolic (DBP) blood pressure readings of the children were taken using automated BP measuring equipment along with anthropometric measurements (heights, weights, skinfold thicknesses and waist measurements). Parental surveys captured items pertaining to the child�s ethnic background as measured by the country of birth of the child and parent(s), residential address and housing structure, child eating habits and activity levels, along with family and child history of high blood pressure. Aircraft noise exposure data were collected by the National Acoustic Laboratories and processed into the energy-averaged noise metric used in Australia for aircraft noise exposure assessment called the Australian Noise Exposure Index (ANEI). Mean exposures for a given calendar month were used in the analysis. ANEI values were geocoded to exact geographic locations using digitised street maps from which values for each house and school address, also geocoded, were interpolated. A child BP measured in a given month was matched to a aircraft noise exposure value both at their school and residential address for that month for analysis. After adjusting for confounding and other factors, the cross-sectional relationship between BP and aircraft noise exposure was found to be inconsistent. SBP was nonsignificantly negatively associated with school aircraft noise exposure at baseline (0.05 mmHg/ANEI, cluster-sampling-adjusted p&gt0.05), but positively and non-significantly associated with school aircraft noise exposure at follow-up (0.05 mmHg/ANEI, p&gt0.05). As for SBP, baseline DBP was significantly negatively related to school aircraft noise exposure at (0.09 mmHg/ANEI, p&lt0.001) and non-significantly positively associated with school aircraft noise exposure at follow-up (0.05 mmHg/ANEI, p&gt0.05). Within-subject BP changes, occurring from baseline to follow-up, regressed on corresponding longitudinal changes in aircraft noise exposures produced inconsistent results. SBP change was positively and non-significantly (0.027 mmHg/ANEI, p&gt0.05) associated with corresponding school aircraft noise exposure change, while SBP change was negatively associated total aircraft noise exposure change (statistically nonsignificant, 0.06 mmHg/ANEI, p&gt0.05). DBP changes were similarly and nonsignificantly related to corresponding aircraft noise exposure changes. Some evidence for short-term BP adaptation to recent changes in aircraft noise exposure was found. Consistent negative associations between systolic and diastolic BP and recent changes in school aircraft noise exposure were found. This association was statistically significant at study baseline (SBP: 0.19 mmHg/ANEI, p&lt0.001; DBP: 0.12 mmHg/ANEI, p&lt0.001), and of similar magnitude although not statistically significant at follow-up (SBP: 0.14 mmHg/ANEI; DBP: 0.10 mmHg/ANEI, p&gt0.05). In the presence of inconsistent cross-sectional BP-aircraft noise exposure associations, this finding is consistent with evidence of a homoeostatic BP response to recent changes in aircraft noise exposure, where resting BP returns to pre-existing levels unrelated to aircraft noise exposure. The public health implication of this finding appears to be benign.
4

Aircraft noise and child blood pressure

Morrell, Stephen Louis January 2003 (has links)
The purpose of the study was to examine the existence of an association between child blood pressure (BP) and exposure to domestic jet aircraft noise in the context of the construction of a new parallel north-south runway at Sydney (Kingsford-Smith) Airport. The baseline study was commissioned and funded by the Federal Airports Corporation (FAC), with measurements conducted in 1994 and 1995. A follow-up longitudinal component to the study was subsequently commissioned and funded by the FAC in 1997, and measurements conducted in the same year. As the same individuals were measured and re-measured over changing conditions of exposure to aircraft noise, the quasiexperimental nature of the study allowed inferences to be made regarding exposure to aircraft noise and child BP. The main hypotheses for testing were that BP, and within-subject longitudinal changes in BP, are positively related to domestic jet aircraft noise exposure and longitudinal changes in domestic jet aircraft noise exposure respectively. Subsidiary hypotheses tested for evidence of short- and long-term BP adaptation effects where BPs were related to prior changes to aircraft noise exposures. A sample of 75 primary schools within a 20 km radius of Sydney Airport under various noise exposure conditions, both existing and those projected with the advent of the new runway, participated in the study. The baseline cohort comprised 1,230 Year 3/4 children attending the schools in 1994 and 1995, and the follow-up participants comprised 628 of the original baseline sample re-measured in 1997. Study participants were enrolled by active parental consent. The baseline response rate was approximately 40% of children in the participating schools. Systolic (SBP) and diastolic (DBP) blood pressure readings of the children were taken using automated BP measuring equipment along with anthropometric measurements (heights, weights, skinfold thicknesses and waist measurements). Parental surveys captured items pertaining to the child�s ethnic background as measured by the country of birth of the child and parent(s), residential address and housing structure, child eating habits and activity levels, along with family and child history of high blood pressure. Aircraft noise exposure data were collected by the National Acoustic Laboratories and processed into the energy-averaged noise metric used in Australia for aircraft noise exposure assessment called the Australian Noise Exposure Index (ANEI). Mean exposures for a given calendar month were used in the analysis. ANEI values were geocoded to exact geographic locations using digitised street maps from which values for each house and school address, also geocoded, were interpolated. A child BP measured in a given month was matched to a aircraft noise exposure value both at their school and residential address for that month for analysis. After adjusting for confounding and other factors, the cross-sectional relationship between BP and aircraft noise exposure was found to be inconsistent. SBP was nonsignificantly negatively associated with school aircraft noise exposure at baseline (0.05 mmHg/ANEI, cluster-sampling-adjusted p&gt0.05), but positively and non-significantly associated with school aircraft noise exposure at follow-up (0.05 mmHg/ANEI, p&gt0.05). As for SBP, baseline DBP was significantly negatively related to school aircraft noise exposure at (0.09 mmHg/ANEI, p&lt0.001) and non-significantly positively associated with school aircraft noise exposure at follow-up (0.05 mmHg/ANEI, p&gt0.05). Within-subject BP changes, occurring from baseline to follow-up, regressed on corresponding longitudinal changes in aircraft noise exposures produced inconsistent results. SBP change was positively and non-significantly (0.027 mmHg/ANEI, p&gt0.05) associated with corresponding school aircraft noise exposure change, while SBP change was negatively associated total aircraft noise exposure change (statistically nonsignificant, 0.06 mmHg/ANEI, p&gt0.05). DBP changes were similarly and nonsignificantly related to corresponding aircraft noise exposure changes. Some evidence for short-term BP adaptation to recent changes in aircraft noise exposure was found. Consistent negative associations between systolic and diastolic BP and recent changes in school aircraft noise exposure were found. This association was statistically significant at study baseline (SBP: 0.19 mmHg/ANEI, p&lt0.001; DBP: 0.12 mmHg/ANEI, p&lt0.001), and of similar magnitude although not statistically significant at follow-up (SBP: 0.14 mmHg/ANEI; DBP: 0.10 mmHg/ANEI, p&gt0.05). In the presence of inconsistent cross-sectional BP-aircraft noise exposure associations, this finding is consistent with evidence of a homoeostatic BP response to recent changes in aircraft noise exposure, where resting BP returns to pre-existing levels unrelated to aircraft noise exposure. The public health implication of this finding appears to be benign.
5

A study of inherent and evoked arousals within sleep

Whitehead, Clare Jane January 1999 (has links)
No description available.
6

Active structural acoustic control of double panel systems including hierarchical control approaches

Carneal, James P. 06 June 2008 (has links)
The general trends and principles of active structural acoustic control when applied to double panel systems are investigated to determine the respective advantages and limitations of this approach. Included is the application of a novel hierarchical control approach which may reduce the controller complexity and the collinearity issue for large order controllers. This research was initiated by an interest in studying the noise transmission path from the noise field generated by an advanced turboprop engine through the aircraft fuselage and the interior trim into the interior acoustic field which can be modeled as a double panel system. The system studied was a double panel model consisting of two rectangular, uniform, flat plates separated by a sealed air cavity, mounted in a transmission loss test facility and excited by an oblique acoustic plane wave. Piezoelectric control inputs were mounted directly on the double panel system incident or radiating plates. Error sensors were microphones placed in the acoustic free field. The cost function was defined as the total radiated sound power from the double panel system. The investigation was carried out analytically with experimental verification. Results of active structural acoustic control (ASAC) applied to double panel systems indicated that the best control performance was exhibited by a double panel system controlled by PZT control actuators mounted on a sandwich board radiating plate. The sandwich board radiating plate double panel system exhibits a decreased coupling of the incident and radiating plates and a lower modal density which results in increased uncontrolled and controlled transmission loss. Piezoelectric (PZT) control actuators should be mounted on the radiating plate of a double panel system which can couple into the radiating acoustic field better than actuators mounted on the incident plate. As expected, better control is achieved with more control actuators since a more distributed forcing function can be attained. However, for on-resonance excitation, the increased number of actuators decreases performance due to collinearity of the actuators which results in spillover. Results of the biologically inspired hierarchical (BIO) control algorithm indicated that significant performance increases over a one output channel controller were attained for all of the BIO methods while performance lagged compared to a full order controller with the same number of control channels. One advantage of the hierarchical control structure was the ability to avoid the collinearity issue when the degrees of freedom excited in the double panel system was less than the number of control channels. In this instance, the hierarchical structure exhibited less spillover than a fully adaptive LQOCT controller. / Ph. D.
7

Valuation of aviation externalities : a case study in Bangkok, Thailand

Cheramakara, Narudh January 2014 (has links)
Aircraft noise, for the first time in Thailand, has gained public attention as a significant environmental issue since Bangkok s Suvarnabhumi Airport opened in 2006. Residential areas around the airport are expanding rapidly while local residents are protesting about the noise from the new airport which suggests a tension between economic benefits and environmental problems at the airport. This thesis sets out to obtain valuation of aviation externalities at Suvarnabhumi airport using the stated choice method. It is the first study to obtain and compare valuations from perspectives of the polluters (Thai air passengers) and the polluted (residents) at the same airport. Furthermore, this is the first study to obtain a valuation of local impacts from aircraft operations and from air passengers. It starts by investigating perceptions and awareness of the benefits and costs of aviation activities among Suvarnabhumi s residents and passengers using focus groups and questionnaires. It then employs the stated choice method to elicit willingness-to-pay (WTP) and willingness-to-accept (WTA) values of aviation externalities. The results found that the perceived environmental problems at Suvarnabhumi airport are in line with the literature mainly involving aircraft noise and its effects. This study also found that the development of the airport and surrounding area, while creating business and employment opportunities, has also created traffic and flooding problems. In terms of air pollution from aircraft, residents concerns are confined to local impacts from aircraft. Thai air passengers were found to be more concerned with engine pollution than noise. These findings were reflected in the values obtained. Two stated choice designs were used to elicit values. The first rerouted the aircraft flight path away from residents homes thus reducing aircraft noise and pollution in the area. This design also included travel time to place of work or to the shops. The rerouting attribute was not statistically significant. However, the travel time attribute reveals that residents were willing to accept 14.23 baht a month to have their travel time to work or shopping increased by 1%. The second design was used to obtain and compare values between Suvarnabhumi s residents and air passengers. In this design, attributes for aircraft noise, local air pollution and carbon emissions were included. Residents willingness to pay to reduce aircraft noise by 1% is 104.76 baht/year whereas passengers are willing to pay less, at 70.63 baht per year. Air passengers place a higher value on local air pollution than the residents. Passengers are willing to pay 97.72 baht to reduce local pollution by 1% per year, whereas residents willingness to pay is 45.36 baht. Lastly, passengers WTP to offset carbon is 473.26 baht per flight, whereas residents carbon offset coefficient is not statistically significant. The obtained values are well within the range of existing studies on aircraft noise and carbon emission valuations. Findings from this study suggest that current mitigation measures at Suvarnabhumi airport are still inadequate. There are areas where the situation is likely to get worse given the rapid growth in aviation activities and urban development at the airport. The values from this study may be used to help form the basis of fairer and more transparent compensation system alongside an operational mitigation policy to address aviation impacts. On the passenger side, the stated willingness-to-pay to reduce the impact gives an opportunity for the Thai aviation industry to promote an environmentally friendly behaviour among the travelling public.
8

Impact of aircraft noise and language on primary school learners' reading comprehension in KwaZulu-Natal.

Kasimonje, Bahati M. 26 March 2013 (has links)
Today’s world is a fast developing world, with the transportation sector being one of the fastest developing sectors (Goldschagg, 2007). Through technologies such as an aircraft, one is able to travel across the globe in shorter periods of time. Unfortunately such progress often comes with environmental hazards; one such hazard being environmental noise (Stansfeld et al., 2005). However there has been little attention given to the effects of environmental noise, with much research focusing on aspects such as lead and air pollution on people’s wellbeing (Stansfeld et al., 2005). Yet environmental noise particularly aircraft noise is increasingly becoming an inevitable part of people’s world and has consequences on health, cognitive development and overall quality of life. Consequently this study investigates the impact of aircraft noise on a crucial component of learning (Reading Comprehension). Primary school learners in KwaZulu- Natal (N=834) scores on a test measuring Reading Comprehension (Suffolk Reading Scale2) were compared across a control group and an experimental group. Furthermore because Reading Comprehension involves language acquisition, in addition to investigating the impact of aircraft noise the impact of having English as an additional language on Reading Comprehension was also investigated. Learning in South Africa is predominantly facilitated in English while South Africa has eleven official languages with nine of them being indigenous languages. English for many learners may only be a second or even third language. Significant results were observed for both aircraft noise and language on reading comprehension as well as an interaction effect.
9

Airport noise in South Africa – Prediction models and their effect on land-use planning

Goldschagg, Paul 12 1900 (has links)
Thesis (DPhil (Geography and Environmental Studies))—University of Stellenbosch, 2007. / The use of average energy aircraft noise contours as the sole means for guiding aircraft noise-based planning around airports is being questioned increasingly. A growing proportion of residents who live in neighbourhoods adjacent to airports are dissatisfied with the averaging procedure that is employed. In their experience of exposure to aircraft noise, particularly in the evening and at night when they are at home, the average energy aircraft noise descriptors are misleading. In order to effectively analyse the socio-spatial interaction of annoyance at and interference by aircraft noise, an alternative approach has been suggested – a supplemental noise perspective. Conventional approaches to aircraft noise land use planning based on average energy noise descriptors run the risk of being ineffectual, or even counterproductive, because they do not consider the central aspects of disturbance, namely the loudness of an event and the number of times events are heard. Consequently, an alternative measure to ameliorate the limitations of average energy noise contours is needed by which airport neighbours, the aviation industry and town planners can better understand the nature of the problem. Although supplemental noise analysis is not new, this study applies it to a South African international airport (OR Tambo) for the first time. The airport’s operations are typical of many busy airports close to large urban areas, serving domestic, regional and international routes. Reportedly, there have been few complaints about noise emanating from the airport, but when they are made they are usually about evening and night-time aircraft noise events. In the context of South Africa as a developing society in transition, where growth of urban settlements continues apace, average energy aircraft noise information must be enhanced by providing supplemental noise information. This study investigated the broad issue of land use planning around airports by employing two aircraft noise prediction models, namely the Integrated Noise Model and the Transparent Noise Information Package, to establish the various potential effects and consequences of night-time aircraft noise in noise zones demarcated according to supplemental aircraft noise information. The effects and consequences examined include annoyance, disturbance of sleep, telephone conversations, watching television and work or study, and the likelihood that people will move away to escape night-time aircraft noise. The perceptions of residents living in neighbourhoods around the airport were surveyed and the responses analysed according to noise zones classified as supplemental noise information. The results show that the airport’s neighbours are annoyed by aircraft noise and that aircraft noise interferes with normal household activities. This annoyance and interference decreases with increasing distance from the airport. Furthermore, reported annoyance and interference is greater in those areas where higher numbers of noise events are encountered, even at relatively low noise levels of 60 LAmax – something not evident from average energy noise contours. This finding strengthens the argument that it is insufficient to provide only average energy aircraft noise information when studying the impact of aircraft noise. To understand the situation more fully, supplemental noise information is essential. The study concludes with a framework constructed to apply supplemental aircraft noise information to the abatement and mitigation measures normally used to deal with aircraft noise.
10

Measuring noise level reduction using an artificial noise source

Robert, Rene Jean 07 January 2016 (has links)
Buildings located near airports may be subjected to significant noise levels due to aircraft flyovers. Aircraft noise is particularly annoying when compared to other traffic noises due to its intermittent nature. While noise control is typically performed at the source, sound insulation programs are in place to improve the acoustic performance of a residence affected by the flyovers. Noise Level Reduction (NLR) is a common metric used in the United States to determine whether a residence qualifies for such programs. Sound insulation programs are available to houses that have an indoor Day Night Average Sound Level (DNL) greater than 45 dBA. NLR is a single-number metric used to quantify the ability for a building or building element to reduce the transmission of external sound pressure levels generated by aircraft. In addition to determining whether a residence qualifies, NLR can be used to quantify the effectiveness of the modifications performed as a result of the sound insulation program. NLR measurements with a loudspeaker offer an alternative method to those performed with aircraft flyovers, offering flexibility to the consultants that perform these measurements in the field. The purpose of this research was to better understand and improve the loudspeaker test for measuring NLR, providing a resource to the aircraft noise industry. Testing was completed on a "test house" that was constructed on campus with construction methods typical of a mixed-humid climate. The angular dependency, repeatability, and reproducibility of NLR, among other factors, were evaluated with field measurements. Significant NLR variations were observed with changes in lateral and vertical angles of incidence.

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