No description available.

In music analysis, the beginning of events in a music signal (i.e. sound onset detection) is important for such tasks as sound segmentation, beat recognition and automatic music transcription. The aim of the present work was to make an algorithm for sound onset detection with better performance than other state-of-the-art1 algorithms. Necessary theoretical background for spectral analysis on a sound signal is given with special focus on the Short-Time Fourier Transform (STFT) and the effects of applying a window to a signal. Previous works based on different approaches to sound onset detection were studied, and a possible improvement was observed for one such approach - namely the one developed by Bello, Duxbury, Davies, & Sandler (2004). The algorithm uses an STFT approach, analyzing a sound signal time frame by time frame. The algorithm’s detection is sequential in nature: It takes a frame from the STFT and makes an extrapolation to the next frame, assuming that the signal is constant. The difference between the extrapolated frame and the actual frame of the STFT constitutes the detection function. The proposed improvement lies in a combination of ideas from other algorithms, analyzing the signal with different frequency bands with frequency dependent settings and a modification of the extrapolation step. The proposed algorithm is compared to the original algorithm and an adaption by Dixon (2006) by analyzing 20 songs using three different window functions. The results were evaluated with the standards set by MIREX (2005-2016). The results of the proposed algorithm are encouraging, showing good recall, but fail to out-perform any of the algorithms it is compared to in both precision and the so-called F-measure. The shortcomings of the proposed algorithm leave room for further improvement, and a number of possible future modifications are exemplified. / Ansatsdetektion används inom musikanalys för bland annat automatisk transkription och ljudkomprimering. Ansatsdetektion innebär att lokalisera en händelse i en musiksignal. Med målet att utveckla en algoritm som presterar bättre än aktuella2 algoritmer ges här en genomgång av några nödvändiga teoretiska kunskaper i ämnet, bland annat korttids-Fouriertransformen (STFT) och hur fönsterfunktioner påverkar signalbehandling. Tidigare arbeten inom ansatsdetektion med olika infallsvinklar studeras och en möjlig förbättring av en av dem, den av Bello, Duxbury, Davies, & Sandler (2004), framträder. Algoritmen använder sig av STFT och analyserar ljudsignaler en tidsenhet i taget. Utifrån varje analyserad tidsenhet görs en extrapolation till nästa tidsenhet genom antagandet att signalen är konstant. Skillnaden mellan den extrapolerade tidsenheten och den faktiska tidsenheten i STFTn utgör detektionsfunktionen. Den möjliga förbättringen består i att använda idéer från olika algoritmer för ansatsdetektion – ljudsignalen analyseras i olika frekvensband med bandberoende inställningar för STFTn – och en förändrad extrapoleringsfunktion. Den föreslagna algoritmen jämförs med originalet av Bello, Duxbury, Davies, & Sandler (2004) och även med en variant utvecklad av Dixon (2006) genom att applicera dem på 20 spår med tre olika fönsterfunktioner. Resultaten utvärderas enligt MIREX (2005-2016) standarder och är lovande för algoritmen, då den har en bra träffbild, men både träffsäkerhet och F-värde ligger under de båda andra. Ett flertal möjliga förbättringar av algoritmen iakttas och presenteras.

No description available.

No description available.

No description available.

No description available.

This cross-sectional survey study investigates the relationship between school attachment (SA) and adolescents' age at first intercourse (DV), as well as the influence of SA on DV in comparison to the influences of parent attachment (PA), other parent and school factors, and individual factors. Early first intercourse is defined as prior to age 15. Participants are 1,757 mostly African-American and White 7th through 12th grade adolescent boys and girls in five rural counties of a Mid-Atlantic state. Bivariate correlations comparing SA and PA revealed significant and positive correlations between SA and DV (p<.001), as well as PA and DV (p<.001). Linear regressions including only SA and PA showed SA was most predictive of DV for adolescents reporting the lowest (p<.05) and highest (p<.001) levels of PA. For those reporting moderate attachment to parents, SA was not predictive of DV. Several ethnic and gender differences are discussed. Finally, when the influence of individual, parent, and school contexts was compared using entry in a regression by blocks, SA was no longer a significant predictor of DV, and school variables did not account for a significant portion in the variance of age at first intercourse. Parent attachment was a significant and negative predictor, indicating that other parent, individual, and community variables are more influential. Implications are discussed. / Master of Science

The fact that traffic congestion upstream of a bottleneck causes a reduction in the discharge flow rate through the bottleneck has been well documented in several empirical studies. However, what has been missing is an understanding of the causes of these empirically observed flow reductions. An identification of these causes is important in order to develop various mitigation schemes through the use of emerging technology. The concept of capacity drop can be introduced at time-independent bottlenecks (e.g. freeways) as well as time-dependent bottlenecks (e.g. signalized intersections). While to the author's knowledge no one has attempted to link these phenomena, the research presented in this thesis serves as a first step in doing so. The research uses the INTEGRATION simulation software, after demonstrating its validity against empirical data, to simulate time-independent and time-dependent bottlenecks in an attempt to characterize and understand the contributing factors to these flow reductions. Initially, the INTEGRATION simulation software is validated by comparing its results to empirically observed traffic stream behavior. This thesis demonstrates that the discharge flow rate is reduced at stationary bottlenecks at the onset of congestion. These reductions at stationary bottlenecks are not recovered as the traffic stream propagates downstream. Furthermore, these reductions are not impacted by the level of vehicle acceleration. Alternatively, the drop in the discharge flow rate caused by time-dependent bottleneck is recoverable and is dependent on the level of acceleration. The difference in behavior is attributed to the fact that in the case of a stationary bottleneck the delay in vehicle headways exceeds the losses caused by vehicle accelerations and thus is not recoverable. In the case of vehicles discharging from a backward recovery wave the dominant factor is the delay caused by vehicle acceleration and this can be recuperated as the traffic stream travels downstream. / Master of Science

No / Purpose: Evidence exists for an additional inhibitory accommodative control system mediated by the sympathetic branch of the autonomic nervous system (ANS). This work aims to show the relative prevalence of sympathetic inhibition in young emmetropic and myopic adults, and to evaluate the effect of sympathetic facility on accommodative and oculomotor function. Methods: Profiling of ciliary muscle innervation was carried out in 58 young adult subjects (30 emmetropes, 14 early onset myopes, 14 late onset myopes) by examining post-task open-loop accommodation responses, recorded continuously by a modified open-view infrared optometer. Measurements of amplitude of accommodation, tonic accommodation, accommodative lag at near, AC/A ratio, and heterophoria at distance and near were made to establish a profile of oculomotor function. Results: Evidence of sympathetic inhibitory facility in ciliary smooth muscle was observed in 27% of emmetropes, 21% of early-onset myopes and 29% of late-onset myopes. Twenty-six percent of all subjects demonstrated access to sympathetic facility. Closed-loop oculomotor function did not differ significantly between subjects with sympathetic facility, and those with sympathetic deficit. Conclusions: Emmetropic and myopic groups cannot be distinguished in terms of the relative proportions having access to sympathetic inhibition. Presence of sympathetic innervation does not have a significant effect on accommodative function under closed-loop viewing conditions.

Lane change or "Side" Crash Avoidance Systems (SCAS) technologies are becoming available to help alleviate the lane change crash problem. They detect lane change crash hazards and warn the driver of the presence of such hazards. This thesis examines driver lane change behavior and evaluates the potential effectiveness of five warning onset rules for lane change or "side" crash avoidance system (SCAS) technologies. The ideal SCAS should warn the driver only when two conditions are met: (1) positive indication of lane change intent and (2) positive detection of a proximal vehicle in the adjacent lane of concern. Together, these two conditions create a crash hazard. The development of SCAS technologies depends largely on an understanding of driver behavior and performance during lane change maneuvers. By quantifying lane change behavior, real world crash hazard scenarios can be simulated. This provides an opportunity to evaluate potential warning onset rules or algorithms of driver intent to change lanes. Five warning onset rules for SCAS were evaluated: turn-signal onset (TSO), minimum separation (MS), line crossing (LC), time-to-line crossing (TLC), and tolerance limit (TL). The effectiveness of each rule was measured by the maximum response time available (tavailable) to avoid a crash for a particular lane change crash scenario, and by the crash outcome, crashed or crash avoided, of a particular lane change crash scenario. / Master of Science