• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 3
  • 1
  • 1
  • 1
  • 1
  • Tagged with
  • 9
  • 9
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 1
  • 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

Design guideline for audible warning signal and determination of sound pressure characteristics : Second version / Riktlinjer för design av hörbara varningssignaler och bestämning av ljudtryckskarakteristik : Andra versionen

Olsson, Mikael, Söderberg, Anders January 2011 (has links)
Today Atlas Copco Rock Drills AB hasn’t got any method to determine how many warning alarms they need on their machines and how they should be mounted to use their full potential. At the moment a travel alarm is usually placed in the front of the machine and a reverse alarm in the back. Then a measurement of the sound pressure level around the machine is performed to see if it is enough to pass the limit according to different ISO-standards. Otherwise they have to mount some extra alarms and then do the measurements again until the standards are fulfilled. The aim of this thesis work is to develop a method for determine how many alarms Atlas Copco Rock Drills AB need on the machines, and also how they should be mounted to fulfil the different criteria according to ISO-standards in the early phase of construction. From the different divisions within Atlas Copco Rock Drills AB (LHD, SDE and TME) arrived four different alarms, which are used on their machines. Sound pressure level measurements were conducted on these, in the anechoic chamber at audiological research centre at the university hospital in Örebro. In the LMS Test.Lab software a measurement sphere was built around the horns and based on the data obtained at the anechoic chamber sound directivity plots were made. Together with earlier machine measurement data from Atlas Copco Rock Drills AB, an Excel program was made constituting an example of how the horns should be mounted. LHD = Loaders and trucks/underground rock excavation SDE = Surface drilling equipment TME = Tunnelling and mining equipment / Idag har Atlas Copco Rock Drills AB inte någon metod för att bestämma hur många varningsalarm som behövs på sina maskiner samt var de ska placeras så de utnyttjar sin fulla potential. I nuläget monteras ett signalhorn vid främre delen och ett backlarm i bakre delen av maskinen. Sedan utförs en ljudtrycksmätning runt maskinen för att kontrollera om man uppfyller kraven från olika ISO-standader. Annars monteras fler alarm och mätningen utförs på nytt tills standarderna uppfylls. Detta examensarbete har som mål att ta fram en metod som bestämmer hur många alarm Atlas Copco Rock Drills AB behöver på sina maskiner, samt hur de skall placeras för att uppfylla kriterierna från olika ISO-standarder redan i konstruktionsstadiet.  Från de olika avdelningarna inom Atlas Copco Rock Drills AB (LHD, SDE och TME) mottogs fyra olika alarm, som används på maskinerna. På dessa utfördes ljudtrycksmätningar i det ekofria rummet vid audiologiskt forskningscentrum på universitetssjukhuset i Örebro. I programmet LMS Test.Lab byggdes en sfär av mätpunkter runt alarmen och baserat på insamlade data från det ekofria rummet konstruerades direktivitetsdiagram. Tillsammans med data som Atlas Copco Rock Drills AB redan hade från tidigare mätningar på maskiner gjordes ett Excel-program, som ger ett exempel på hur alarmen bör monteras. LHD = Loaders and trucks/underground rock excavation SDE = Surface drilling equipment TME = Tunnelling and mining equipment
2

Evaluation and Installation Guidelines for Advance Warning Signal Systems in Utah

Jensen, Aaron Paul 04 May 2007 (has links) (PDF)
Advance warning signals (AWS) provide information warning drivers in advance of the end-of-green phase for an approaching signalized intersection. The purpose of this research was to develop guidelines for the placement of AWS in Utah, both conditions to evaluate the need for AWS installation and guidelines for the AWS system design. The conditions were based on literature of other transportation agencies that had similar AWS systems and were developed using the Policy Delphi method. The Policy Delphi method is the development of a specific policy area through the means of discussion by a committee of experts correlating views and information involving opportunity to react and assess different viewpoints until the committee is in agreement over the policies being recommended. Six conditions are recommended and discussed in detail, including: limited sight distance, posted speed, isolated intersection, high crash rate, approach grade, and heavy vehicle traffic volume. The guidelines for the AWS system design included details about three components: AWS component, advance detection component, and signal timing component. An evaluation matrix was developed by the Policy Delphi method for the purpose of evaluating and prioritizing a group of intersections for AWS installation. A total of 24 intersections were identified by the Utah Department of Transportation for this project that helped to develop and verify the conditions and evaluation matrix. The recommended guidelines and evaluation matrix results are described.
3

The modality shift effect and the effectiveness of warning signals in different modalities

Rodway, Paul January 2005 (has links)
No / Which is better, a visual or an auditory warning signal? Initial findings suggested that an auditory signal was more effective, speeding reaction to a target more than a visual warning signal, particularly at brief foreperiods [Bertelson, P., & Tisseyre, F. (1969). The time-course of preparation: confirmatory results with visual and auditory warning signals. Acta Psychologica, 30. In W.G. Koster (Ed.), Attention and Performance II (pp. 145-154); Davis, R., & Green, F. A. (1969). Intersensory differences in the effect of warning signals on reaction time. Acta Psychologica, 30. In W.G. Koster (Ed.), Attention and Performance II (pp. 155-167)]. This led to the hypothesis that an auditory signal is more alerting than a visual warning signal [Sanders, A. F. (1975). The foreperiod effect revisited. Quarterly Journal of Experimental Psychology, 27, 591-598; Posner, M. I., Nissen. M. J., & Klein, R. M. (1976). Visual dominance: an information-processing account of its origins and significance. Psychological Review, 83, 157-171]. Recently [Turatto, M., Benso, F., Galfano, G., & Umilta, C. (2002). Nonspatial attentional shifts between audition and vision. Journal of Experimental Psychology; Human Perception and Performance, 28, 628-639] found no evidence for an auditory warning signal advantage and showed that at brief foreperiods a signal in the same modality as the target facilitated responding more than a signal in a different modality. They accounted for this result in terms of the modality shift effect, with the signal exogenously recruiting attention to its modality, and thereby facilitating responding to targets arriving in the modality to which attention had been recruited. The present study conducted six experiments to understand the cause of these conflicting findings. The results suggest that an auditory warning signal is not more effective than a visual warning signal. Previous reports of an auditory superiority appear to have been caused by using different locations for the visual warning signal and visual target, resulting in the target arriving at an unattended location when the foreperiod was brief. Turatto et al.'s results were replicated with a modality shift effect at brief foreperiods. However, it is also suggested that previous measures of the modality shift effect may still have been confounded by a location cuing effect.
4

Rozlišování nevhodné kořisti ptačími predátory / Dangerous prey recognition in avian predators

VESELÝ, Petr January 2010 (has links)
The present PhD thesis comprises four published research papers and two manuscripts in preparation dealing with importace of particular parts of the warning signal in protection of insect prey against avian predators.
5

Impact d’un systeme anticollision sur le traitement de l'information et le comportement du conducteur / Impact of a collision warning system on information processing and driver behaviour

Bueno garcia, Mercedes 27 September 2013 (has links)
Ce travail de thèse a été centré sur l’analyse de l’impact d’un système d’alerte anticollision sur le traitement de l’information et le comportement du conducteur en conduite automobile simulée. Les objectifs de ce travail étaient 1) de déterminer l’impact d’un signal avertisseur associé à un système d’alerte anticollision sur le traitement de l’information à partir de potentiels évoqués ; 2) d’analyser l’efficacité d’un tel système en fonction de sa fiabilité ; 3) et en fonction de l’état attentionnel des conducteurs ; et 4) d’examiner l’adaptation comportementale au système au cours du temps. Grâce à une double approche comportementale et électrophysiologique, nous avons montré que le signal avertisseur agit au niveau de l’anticipation et de la préparation à la réponse ainsi qu’au niveau cognitif du traitement de l’information. Par ailleurs, nous avons confirmé que les systèmes anticollision ne nécessitent pas d’être complètement fiables pour être efficaces. Nous avons également observé que l’efficacité du signal avertisseur associé au système anticollision était moindre chez les sujets distraits, notamment lorsque la charge cognitive associée à la distraction était élevée. Ceci suggère que le signal avertisseur nécessite des ressources attentionnelles pour être traité et, donc, pour être efficace. Concernant l’adaptation comportementale au système, les principaux résultats ont montré, d’une part, que l’introduction immédiate du système a eu un effet positif sur le comportement de conduite et, d’autre part, que le processus d’adaptation au système à plus long terme peut être affecté si les conducteurs sont distraits par des tâches secondaires coûteuses en ressources attentionnelles. / This thesis was focused on the analysis of the impact of a collision warning system on information processing and driver behaviour in simulated driving. The objectives of this work were 1) to determine the impact of a warning signal associated with a collision warning system on the processing of information using evoked potentials, 2) to analyse the effectiveness of such a system according to its reliability, 3) and according to the drivers’ attentional state, 4) to examine the behavioural adaptation to the system over time. Using an electrophysiological and behavioural dual approach, we showed that the warning signal acts at the level of anticipation and response preparation and at the level of cognitive processing. Moreover, we confirmed that collision warning systems do not need to be completely reliable to be effective. We also observed that the effectiveness of the warning signal associated with the collision warning system was lower in distracted subjects, especially when the cognitive load associated with the distraction was high. This suggests that the warning signal requires attentionnal resources in order to be processed and, therefore, to be effective. Concerning behavioural adaptation to the system, the main results showed firstly that the immediate introduction of the system had a positive effect on the driving behaviour and secondly that the process of adaptation of the system at the longer term may be affected if drivers are distracted by high demanding secondary tasks.
6

Evolution of Mimicry and Aposematism Explained: Salient Traits and Predator Psychology

Kazemi, Baharan January 2017 (has links)
Aposematic species have evolved conspicuous warning signals, such as bright colors and striking patterns, to deter predators. Some edible and harmless species take advantage of this deterrent effect by mimicking their appearance. Mimicry is a great example of how natural selection produces remarkable adaptations. However, while some species evolve a very close similarity to their models to effectively avoid attacks, others are successful in doing so despite an incomplete similarity, i.e. imperfect mimicry. In some cases, it is surprising how such a crude disguise can fool predators. Why and how imperfect mimicry can persist has been much discussed and considered as a problem for the theory of natural selection. It is therefore of great interest to understand what makes it possible. Predator psychology is an important factor in the evolution of aposematism and mimicry. In the past decades it has been suggested that certain components of prey appearance are more important to predators than others during prey assessment. We developed this idea by incorporating concepts from associative learning, and presented a new approach to explain imperfect mimicry. Our general hypothesis is that prey traits have different salience to predators. Certain traits are perceived as highly salient and are thus used primarily in the discrimination and generalization of prey, while traits with low salience are overshadowed and not used in the assessment. The salience of a trait can depend on how conspicuous or discriminable it is in the particular context, and can vary due to for example previous predator experience. We tested our ideas with wild blue tits and domestic chickens as predators, and artificial and semi-natural prey stimuli. In paper I we found that the trait that was perceived as most salient (color) was the one used to discriminate and generalize between prey. Mimics of that specific trait were highly avoided, despite differences in the other traits. We also found that salience is relative and context dependent (paper II). In a context where two traits were perceived as similarly salient, mimicry of a single trait offered intermediate protection, while mimicry of both offered high protection. In another context, the traits were perceived differently salient, and mimicry of one trait was enough for high protection. In paper III we tested a proposed scenario for the initiation of mimicry evolution in the edible butterfly mimic Papilio polyxenes asterius to its noxious model Battus philenor. The results showed that a partial similarity with the model in the salient black wing color offered intermediate protection from attacks, despite a general dissimilarity. This thesis investigates the major questions of imperfect mimicry: the initial step of mimicry evolution, the persistence of imperfect mimicry, and variation in mimic-model similarity. We conclude that mimicry evolution can begin in a non-mimetic species that acquires similarity to a model species in a high-salience trait. When multiple traits have similar salience, multi-trait mimicry is needed for higher protection. Mimicry can remain imperfect if the differences are in traits with low salience, and therefore under low or no selection pressure to change. To complete the picture, we showed that predators can have a biased generalization toward a more pronounced version of a salient trait (paper IV). The evolution of aposematism could therefore be explained by gradual enhancement of salient traits. / <p>At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 3: Accepted. Paper 4: Manuscript.</p>
7

Evaluation of the Effectiveness of Blank-Out Overhead Dynamic Advance Warning Signal Systems

Peterson, Ryan 24 June 2006 (has links) (PDF)
Advance warning signals installed upstream of a high-speed signalized intersection (HSSI) warn motorists of impending signal changes in an effort to reduce the frequency of red-light running (RLR) and crashes. A new advance warning signal design was tested on an approach to an HSSI in Utah to study the effects of the modified design on motorist behavior. The new design utilized an overhead dynamic blank-out sign and flashers. A state-of-the-art digital wave radar evaluation system was installed at the study site to collect continuous data of vehicle speeds and RLR events by a non-intrusive method. Crash data were collected from the jurisdiction responsible for the study site and for an additional control intersection. Data were collected prior to, immediately after, and eight months after installation The blank-out overhead dynamic advance warning signal (BODAWS) system reduced RLR at the site during the time period immediately after installation. Eight months later, the number of RLR violations was slightly higher on one approach than before BODAWS system installation. Crash results showed that six months after BODAWS installation, the number of crashes declined at the study site. The number of crashes proportionately declined at the control intersection as well indicating a need to continue to evaluate and monitor changes. Mean vehicle speeds recorded before the onset of the yellow signal increased on the approaches to the study site immediately after BODAWS installation, and remained higher eight months later. Mean vehicle speeds recorded during the yellow signal, increased eight months after BODAWS installation to speeds higher than before the system was installed. Higher speeds during the yellow signal, combined with an increase in the number of RLR violations eight months after BODAWS installation, suggest that motorists may have begun to use the advance warning to speed up in an attempt to enter the intersection before the signal turned red. It is recommended that the lead flash time between activation of the BODAWS signs and flashers and the onset of the yellow signal should be adjusted so that motorists are not provided with more time than is necessary to safely clear the intersection.
8

Azimuthal Localization and Detection of Vehicular Backup Alarms Under Electronic and Non-Electronic Hearing Protection Devices in Noisy and Quiet Environments

Alali, Khaled Ahmed 04 May 2011 (has links)
Objective assessment for the effect of hearing protectors, background noise levels, and backup alarm acoustic features on listeners' abilities to localize backup alarm signals in the horizontal dimension, as well as on their ability to detect backup alarm signals in the distance dimension, is lacking in the acoustics and safety literature. Accordingly, two research experiments were conducted for this dissertation. In the first experiment, the effect of seven hearing protectors, two background pink noise levels (60 dBA and 90 dBA), and two backup alarm signals (standard and spectrally-modified) on the ability of normal hearing listeners to localize backup alarm signals in the horizontal dimension was investigated. Results indicated that a diotic sound transmission earmuff significantly degraded localization accuracy as compared to all other hearing protectors and the open ear condition. In addition, no significant difference existed between the open ear condition and the other hearing protectors in localization accuracy in most of the conditions tested. However, the E-A-R/3M HiFiTM earplug was advantageous in localization performance since it provided a significantly higher percentage correct localization than the Moldex foam earplug, the diotic earmuff, and the dichotic earmuff in 90 dBA pink noise. As for main effects of the other independent variables, the 90 dBA pink noise significantly degraded localization performance as compared to the quiet condition of 60 dBA, and a spectrally-modified backup alarm significantly improved localization performance as compared to the standard (narrowband) backup alarm. Potential application of these results includes the revision of backup alarm standards. In addition, these results provide clear advice for safety professionals to avoid the application of diotic sound transmission earmuffs for workers if localizing backup alarms is important. In the first experiment, listeners' feeling of comfort for each hearing protector was assessed subjectively by using a comfort rating scale. In addition, a subjective assessment for listeners' confidence in their localization decisions was established. Results indicated no significant difference between the hearing protectors in terms of comfort. However, in terms of listeners' confidence in localization decisions, their confidence was significantly degraded when they were fitted with the diotic earmuff. By contrast, they showed significantly more confidence in their localization decisions when they were fitted with the E-A-R/3M HiFi™ earplug as compared to when they were fitted with the Moldex foam earplug, the E-A-R/3M Ultrafit™ earplug, and the Bilsom passive earmuff. In the second experiment, listeners' performance in detecting a stationary backup alarm signal, including both a standard (narrowband) and broadband (pulsed white noise) alarm, was determined while they were equipped with various passive and electronic hearing protection devices. Listeners' performance was quantified by detection distance, which was defined as the distance between the stationary backup alarm device and the position where the listener detected the backup alarm signal. The resultant data demonstrated that normal hearing listeners detected a standard (narrowband) backup alarm signal at significantly longer distances as compared to the broadband (Brigade™) backup alarm signal, thus indicating the earlier forewarning by the standard alarm. In addition, passive hearing protection devices characterized with high attenuation significantly reduced the detection distance. These results may be applied to assist safety professionals in selecting hearing protectors and backup alarm signals that provide on-foot workers with ample time to react to an approaching backing vehicle, thus improving their safety. / Ph. D.
9

模糊統計在社會調查之應用 / The Application of Fuzzy Statistics in Social Survey

鄭勝元 Unknown Date (has links)
在問卷設計上,一般人常用傳統勾選的方式讓受訪者作答。這種0或1的二分法方式,讓受訪者在數個選項中勾選出一個較適當之答案,但其勾選的並非絕對,而其無勾選的卻非不曾發生的,如此所得到的資料往往會扭曲事實的真相。   本論文即是利用模糊之概念來改良傳統之問卷,允許受訪者在數個選項中填寫百分比,解決上述傳統問卷之缺失,並以家庭關係問卷為例,來比較傳統及模糊問卷結果的差異性。更進一步建構一家庭關係模糊指標及定義一家庭關係警訊燈號,用來衡量一般人家庭關係之優劣。分析結果我們可以得到以下三點結論:1.傳統問卷之結果,往往容易集中在某個選項上;而模糊呈現的較為均衡。2.由於模糊問卷答題方式較為多樣化,故家庭關係模糊指標分布較為廣泛且均勻。3.整體而言,較多數人之家庭關係警訊燈號為綠燈,顯示家庭關係不錯。 / In survey question design, people used the method of traditional selection to let respondent to answer. This method let respondent to select an appropriate answer in several options. However, his selections would not be absolute, and the options that he did not select would happen. Such data may skew the reality.   In this paper, we make use of fuzzy concept which allow respondent to write down percentage in several options to improve traditional survey question and to resolve the shortcoming of traditional survey. Also, we take family relation survey question for instance to compare the difference of traditional and fuzzy survey question result. Furthermore, we build a family relation fuzzy index and define a family relation warning signal to judge the good and the bad of one's family relation.

Page generated in 0.0734 seconds