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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.
11

Parental care of peregrine falcons in interior Alaska and the effects of low-altitude jet overflights

Palmer, Angela G. 14 December 1998 (has links)
To assess the impact of low-altitude jet overflights on parental care, we examined nest attendance, time-activity budgets, and provisioning rates of 21 Peregrine Falcon (Falco peregrinus) pairs breeding along the Tanana River, Alaska in 1995 and 1996. Several intrinsic and extrinsic factors influenced attributes of nesting behavior. Female nest attendance declined substantially with progression of the nesting cycle, while male attendance patterns were consistent throughout the nesting cycle. Further, although females typically performed most of the incubating, male attendance at the nest area varied considerably among breeding pairs. Both prey item delivery rates and estimated prey mass delivery rates increased with brood size. Prey item delivery rates per nestling, however, decreased with increasing brood size; yet estimated prey mass delivery rates per nestling did not vary with brood size. Peregrine Falcons apparently maintained constant provisioning rates per nestling as brood size increased by increasing average prey size. We found evidence that nest attendance and time-activity budgets of Peregrine Falcons differed during periods of overflights compared with reference nests, but differences depended on stage of the nesting cycle and gender. Males had lower nest ledge attendance during periods when overflights occurred than males from reference nests when data from the incubation and early nestling-rearing stages of the nesting cycle were combined. Females apparently compensated for lower male ledge attendance by attending the ledge more during overflown periods compared to females from reference nests, although this trend was not significant. During late nestling-rearing, however, females perched in the nest area less during periods when overflights occurred than females from reference nests. We did not see a relationship between nest attendance and the number of overflights, the cumulative number of exposures experienced by each nesting pair, or the average sound exposure level of overflights. Nor did we find evidence that nestling provisioning rates were affected by overflights. Low altitude jet overflights did not markedly affect nest attendance, time-activity budgets, or nestling provisioning rates of breeding Peregrine Falcons. / Graduation date: 1999
12

Vliv způsobu nakládání krmiva do krmného míchacího vozu na životní prostředí

PULKRAB, Miroslav January 2017 (has links)
This thesis aims to determine the effect of methods of loading feed to the mixer feeder wagon on the environment. Two types of loading devices were chosen for observation in the selected agricultural enterprise. The first part of this thesis deals with machines and equipment for feeding of cattle as well as sources, division and effects of noise. In the second part there is described the methodology of measuring noise, characteristics of observed mixer feeder wagons and graphical representation of measured values. The conclusion of this thesis deals with comparison of the measured values and evaluation of this issue.
13

The effect of type and level of noise on long-term average speech spectrum (LTASS)

劉淑, Lau, Suk-han. January 1998 (has links)
published_or_final_version / Speech and Hearing Sciences / Master / Master of Science in Audiology
14

Detection and classification of marine mammal sounds

Unknown Date (has links)
Ocean is home to a large population of marine mammals such as dolphins and whales and concerns over anthropogenic activities in the regions close to their habitants have been increased. Therefore the ability to detect the presence of these species in the field, to analyze and classify their vocalization patterns for signs of distress and distortion of their communication calls will prove to be invaluable in protecting these species. The objective of this research is to investigate methods that automatically detect and classify vocalization patterns of marine mammals. The first work performed is the classification of bottlenose dolphin calls by type. The extraction of salient and distinguishing features from recordings is a major part of this endeavor. To this end, two strategies are evaluated with real datasets provided by Woods Hole Oceanographic Institution: The first strategy is to use contour-based features such as Time-Frequency Parameters and Fourier Descriptors and the second is to employ texture-based features such as Local Binary Patterns (LBP) and Gabor Wavelets. Once dolphin whistle features are extracted for spectrograms, selection of classification procedures is crucial to the success of the process. For this purpose, the performances of classifiers such as K-Nearest Neighbor, Support Vector Machine, and Sparse Representation Classifier (SRC) are assessed thoroughly, together with those of the underlined feature extractors. / Includes bibliography. / Dissertation (Ph.D.)--Florida Atlantic University, 2014. / FAU Electronic Theses and Dissertations Collection
15

Acoustic modelling study of seismic airgun noise in Queen Charlotte Basin

MacGillivray, Alexander Orion 11 February 2010 (has links)
This thesis presents a methodology for modelling underwater sound propagation from seismic airgun surveys. Subsequently, the method is applied to the case of predicting noise levels from offshore oil and gas exploration in the Queen Charlotte Basin region of the British Columbia offshore. Underwater noise levels are predicted using an integrated mod¬elling approach that incorporates (i) an airgun array source model. (ii) a broadband 3-D transmission loss model, and (iii) environmental databases of high resolution bathymetry. historical CTD casts and geoacoustic properties of the seabed. As part of this thesis, an airgun array source signature model is developed and then used for predicting the acoustic source level of a seismic airgun array. The airgun model, based on the physics of the oscillation and radiation of airgun bubbles, is validated against real airgun data. Under-water sound propagation is modelled in three dimensions using a parabolic-equation (PE) based, "Nx2-D" transmission loss model. Broadband sound propagation is approximated by modelling acoustic transmission loss at third-octave band centre frequencies; noise levels are computed by subtracting transmission loss from the respective third-octave band airgun array source levels. High resolution bathymetry and geoacoustic data for Queen Charlotte Basin are extracted along centrolineal radial transects for input to the propagation model. Additionally, principal component analysis is applied to a large collection of historical CTD data to extract seasonal sound speed profile variations. Transmission loss is modelled using both winter and summer sound speed profiles to bracket seasonal variations in acoustic propagation conditions. Noise level estimates from the acoustic modelling may be used to determine impact zones around the survey vessel where marine mammals are expected to exhibit disturbance reactions to airgun noise. Results from this study will aid in evaluating the potential environmental impacts of seismic exploration activity on marine ecosystems in British Columbia's offshore region.
16

Formulation and implementation of a generic fleet-level noise methodology

Bernardo, Jose Enrique 08 April 2013 (has links)
The expected rise in aviation demand requires the reduction of the environmental impacts that impede this desired growth, such as fuel burn, emissions, and airport noise. A number of current technology programs attempt to identify, evaluate, and select the environmental technology solutions for the coming decades. Fleet-level evaluation will be essential to deciding between various technology options because it provides a system-level assessment that clarifies the effect of operational and policy variables. Fleet-level modeling in general, introduces various complexities, and detailed fleet-level models require significant time and computing resources to execute. With a large number of potential technology options available for assessment, a full detailed analysis of the technology space is infeasible. Therefore, a simplified fleet-level environmental evaluation methodology is required to select scenarios to carry forward for detailed modeling. Capabilities such as the Global and Regional Environmental Aviation Tradeoff (GREAT) tool, have achieved rapid simplified fleet-level analysis for fuel burn and emissions, but currently lack a satisfactory generic framework to evaluate fleet-level noise. The primary objective of this research is to formulate and implement a generic fleet-level noise methodology that allows decision makers to analyze the fleet-level impact of many technology scenarios on the quantity of noise, and also its distribution about certain airport types. This information can be leveraged to provide screening assessments of technology impacts earlier in the decision-making process, reserving more sophisticated modeling techniques for the most promising scenarios. The capability gaps identified are addressed by the development of a rapid generic fleet-level noise model that captures basic airport noise contour shape and contour area, a categorization of airports with respect to their operational and infrastructure characteristics, and the development of shape metrics that enable rapid classification and comparison of contour shapes. Once the capability gaps were addressed, the resultant System-Wide Assessment of Noise (SWAN) methodology was implemented via use cases to demonstrate the application of the methodology, examining the introduction of a set of possible near-term (N+1) future technologies into the forecast. While these examples are simplified and notional, they demonstrate the types of analyses and investigations that can be performed with the SWAN methodology, providing answers regarding the impact of technologies on contour shapes. The development, verification, validation, and demonstration of these capabilities complete a framework for evaluating fleet-level noise at the screening-level that retains the ability to capture and effectively discuss shape information beyond the capability of current screening-level noise evaluation techniques. By developing a rapid generic fleet-level noise model, a set of Generic Airports, and metrics that objectively quantify and describe shape, decision-makers can access greater levels of information, including the critical facet of contour shape in fleet-level airport noise.
17

A Parabolic Equation Analysis of the Underwater Noise Radiated by Impact Pile Driving

Laws, Nathan 05 July 2013 (has links)
Impact pile driving can produce extremely high underwater sound levels, which are of increasing environmental concern due to their deleterious effects on marine wildlife. Prediction of underwater sound levels is important to the assessment and mitigation of the environmental impacts caused by pile driving. Current prediction methods are limited and do not account for the dynamic pile driving source, inhomogeneities in bathymetry and sediment, or physics-based sound wave propagation. In this thesis, a computational model is presented that analyzes and predicts the underwater noise radiated by pile driving and is suitable for shallow, inhomogeneous environments and long propagation ranges. The computational model uses dynamic source models from recent developments in the technical literature. Pile source models are coupled to a broadband application of the range-dependent acoustic model (RAMPE), a standard parabolic equation (PE) propagation code capable of modeling wave propagation through complex, range dependent environments. Simulation results are shown to be in good agreement with several observations of pile driving operations in the Columbia River between Portland, Oregon and Vancouver, Washington. The model is further applied to extend sound level predictions over the entire river and study the effects of sediment and bathymetry on the underwater sound levels present in the environment.
18

Detecting, assessing, and mitigating the effects of naval sonar on cetaceans

Wensveen, Paul J. January 2016 (has links)
Effective management of the potential environmental impacts of naval sonar requires quantitative data on the behaviour and hearing physiology of cetaceans. Here, novel experimental and analytical methods were used to obtain such information and to test the effectiveness of an operational mitigation method for naval sonar. A Bayesian method was developed to estimate whale locations through time, integrating visual observations with measurements from on-animal inertial, acoustic, depth, and Fastloc-GPS sensors. The track reconstruction method was applied to 13 humpback whale (Megaptera novaeangliae) data sets collected during a multi-disciplinary behavioural response study in Norwegian waters. Thirty-one controlled exposure experiments with and without active transmissions of 1.3-2 kHz sounds were conducted using a moving vessel that towed a sonar source. Dose-response functions, representing the relationships between measured sonar dose and behavioural responses identified from the reconstructed tracks, predicted that 50% of the humpbacks would initiate avoidance at a relatively high received sound pressure level of 166 dB re 1 µPa. Very similar dose-response functions were obtained for cessation of feeding. In a laboratory study, behavioural reaction times of a harbour porpoise (Phocoena phocoena) to sonar-like sounds were measured using operant conditioning and a psychoacoustic method. Auditory weighting functions, which can be used to improve dose-response functions, were obtained for the porpoise based on the assumption that sounds of equal loudness elicit equal reaction time. Additional analyses of the humpback whale data set provided evidence that ramp-up of naval sonar mitigates harmful sound levels in responsive cetaceans located directly in the path of the source, and suggested that a subset of the humpback whale population, such as mother-calf pairs, and more responsive species would benefit from the use of sonar ramp-up. The findings in this thesis are intended to inform sound exposure criteria and mitigation guidelines for anthropogenic noise exposure to cetaceans.

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