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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

Measurement and subjective assessment of water generated sounds

Watts, Gregory R., Pheasant, Robert J., Horoshenkov, Kirill V., Ragonesi, L. 01 November 2009 (has links)
Yes / There is increasing concern with protecting quiet and tranquil areas from intrusive noise. Noise reduction at source and barriers to transmission are mitigation measures often considered. An alternative is to attempt to mask or distract attention away from the noise source. The masking or distracting sound source should be pleasant so that it does not add to any irritation caused by the noise source alone. The laboratory measurements described in this paper consisted of capturing under controlled conditions the third octave band spectra of water falling onto water, gravel, bricks and small boulders and various combinations. These spectra were then matched with typical traffic noise spectra to assess the degree of masking that could be expected for each option. Recordings were also taken during each measurement and these were used later to enable the subjective assessment of the tranquility of the sounds. It was found that there were differences between water sounds both in terms of masking and their subjective impact on tranquility.
2

An investigation on subjective assessments of workload and postural stability under conditions of joint mental and physical demands

DiDomenico, Angela Terese 30 July 2003 (has links)
Workload is defined as the cost incurred by an individual, given their capacities, while achieving a particular level of performance on a task with specific demands. Demands of a task or combination of tasks may include maintaining postural stability, executing physical actions, and/or performing cognitive tasks. While there have been attempts to establish a physiological measure of concurrent physical and mental workload, as yet there has been no work towards developing a single subjective method of evaluation. Select subjective assessment methodologies were evaluated quantitatively during laboratory-based experiments. Concurrent execution of mental and physical activity was required at various levels, since it was desired to be able to measure mental workload, physical workload, and also evaluate their interaction. Measurements of task performance were investigated to evaluate the effects of combined mental and physical demands and establish which subjective assessments were accurate and sensitive to changes in workload. The utility of existing subjective assessment tools created for one domain appeared to be limited when evaluating multi-task situations requiring substantial mental and physical activity. Further clarification of the impact of different types of physical demand on cognitive processing, performance and subjective workload assessment of a constant mental task was addressed in the second experiment. This experiment investigated the effect of several activity types, specifically global versus localized effort, changes in load, and different task frequencies. The results provided support that the type of activity, load and frequency of task influence subjective mental workload assessment scores and performance. Not all existing assessment tools accurately represented an individual's ability to perform a task when there was a combination of physical and mental demands. A unidimensional tool is suggested as a screening tool to identify situations requiring excessive or increased mental workload. Alternative methods, possibly a new multidimensional tool, should be developed to obtain more detailed information so ratings of workload for different tasks may be compared. Effectiveness of a subjective stability assessment tool was evaluated in situations demanding mental activity while maintaining an upright posture. Tests were performed over a wide range of conditions, including various mental loads, sensory conditions, and postural stances. The purpose was to determine the effects of each task variation on the perception of postural stability. Postural sway increased with task difficulty, regardless of the source (i.e. postural stance, visual condition, mental workload). The addition of mental workload did not alter the non-linear relationship between objective measures of postural sway and perceptions of postural stability. Since decrements in balance are well perceived, subjective assessment tools may be incorporated in control strategies to minimize falls. / Ph. D.
3

Links between Subjective Assessments and Objective Metrics for Steering

Su, He, Zhicheng, Xuxin January 2012 (has links)
The characteristics of vehicle steering perception are decisive factors concerning vehicle safety and overall pleasure behind the wheel. It is a challenge for vehicle manufacturers to achieve these features and qualities, because usually vehicle tuning almost only relies on subjective evaluation of test drivers, which is costly and time consuming. In order to optimize suspension design and develop a tool that can be used to evaluate steering with objective metrics instead of subjective assessment, links between them must be confirmed. In this master thesis, both objective and subjective testing data of over 20 vehicles across four different segments are introduced in linear and nonlinear analysis. Linear regression analysis is applied to investigate simply positive or negative correlation between a pair of subjective-objective parameters. However, even if certain linear correlations are obtained, it is still hard to define the optimal value for objective metrics. Considering that the general shape of a correlation function can reveal which objective range give higher subjective rating, it is possible to define these preferred ranges with Neural Network (NN). The best data available is adopted from three drivers who tested 15 sedans, and some interesting results are found. The initial results demonstrate that NN is a powerful tool to uncover and graphically illustrate the links between objective metrics and subjective assessments, i.e., the specific range leading to better steering feel. Given a larger sample size, more reliable and optimal links can be defined by following the same method. These confirmed links would enable vehicle dynamics engineers to more effectively develop new vehicles with nearly perfect steering feel.
4

LEFT VENTRICULAR EJECTION FRACTION: A RETROSPECTIVE STUDY COMPARING 2D ECHOCARDIOGRAPHY AND GATED SINGLE PHOTON EMISSION COMPUTED TOMOGRAPHY (SPECT) IN CLINICAL USE.

Andersson, Jim January 2009 (has links)
<p><strong>Objectives</strong></p><p>The aim of this study was to compare left ventricular ejection fraction (LVEF) results derived from gated single photon emission computed tomography (SPECT) using Cedars-Sinai quantitative gated SPECT (QGS) processing software with results from 2D echocardiography, both obtained in routine clinical diagnostic use.</p><p> </p><p><strong>Methods</strong></p><p>Data from previously performed tests were obtained from 73 patients who had undergone both 2D echocardiography and gated SPECT within a time span of 6 months and had not had significant events that could influence LVEF. LVEF from 2D echocardiography was reassessed to obtain discrete values and then the data was compared using Bland-Altman analysis.</p><p> </p><p><strong>Results</strong></p><p>The correlation between the tests was shown to be good, but precision lacked. Bland-Altman analysis showed a bias of -0.8 percentage points when gated SPECT compared to mean values and 2 standard deviations (SD) ranged from -20.2 to 18.6.</p><p> </p><p><strong>Conclusions</strong></p><p>LVEF values from the two methods can differ quite a bit and comparisons between them should be done with great caution.</p> / <p><strong>Syfte</strong></p><p>Syftet med studien var att jämföra hur bra ultraljud av hjärta och isotopundersökning av hjärta stämmer överens när det gäller att visa hjärtats pumpförmåga.</p><p> </p><p><strong>Metod</strong></p><p>Data från tidigare utförda undersökningar av 73 patienter jämfördes. Patienter som hade gjort båda undersökningarna inom 6 månader och under perioden mellan undersökningarna inte hade haft hjärtinfarkt eller någon annan händelse som kan påverka hjärtats pumpförmåga valdes till studien.</p><p> </p><p><strong>Resultat</strong></p><p>Utslaget över hela studiepopulationen stämde resultaten från de båda undersökningarna bra överens. Jämförde man däremot resultaten från de båda undersökningarna med varandra patient för patient förekom mycket stora variationer.</p><p> </p><p><strong>Slutsats</strong></p><p>Resultaten angående hjärtats pumpförmåga kan skilja sig mycket från varandra. Jämförelser av värden från dessa två metoder bör därför göras med väldigt stor försiktighet.</p>
5

LEFT VENTRICULAR EJECTION FRACTION: A RETROSPECTIVE STUDY COMPARING 2D ECHOCARDIOGRAPHY AND GATED SINGLE PHOTON EMISSION COMPUTED TOMOGRAPHY (SPECT) IN CLINICAL USE.

Andersson, Jim January 2009 (has links)
Objectives The aim of this study was to compare left ventricular ejection fraction (LVEF) results derived from gated single photon emission computed tomography (SPECT) using Cedars-Sinai quantitative gated SPECT (QGS) processing software with results from 2D echocardiography, both obtained in routine clinical diagnostic use.   Methods Data from previously performed tests were obtained from 73 patients who had undergone both 2D echocardiography and gated SPECT within a time span of 6 months and had not had significant events that could influence LVEF. LVEF from 2D echocardiography was reassessed to obtain discrete values and then the data was compared using Bland-Altman analysis.   Results The correlation between the tests was shown to be good, but precision lacked. Bland-Altman analysis showed a bias of -0.8 percentage points when gated SPECT compared to mean values and 2 standard deviations (SD) ranged from -20.2 to 18.6.   Conclusions LVEF values from the two methods can differ quite a bit and comparisons between them should be done with great caution. / Syfte Syftet med studien var att jämföra hur bra ultraljud av hjärta och isotopundersökning av hjärta stämmer överens när det gäller att visa hjärtats pumpförmåga.   Metod Data från tidigare utförda undersökningar av 73 patienter jämfördes. Patienter som hade gjort båda undersökningarna inom 6 månader och under perioden mellan undersökningarna inte hade haft hjärtinfarkt eller någon annan händelse som kan påverka hjärtats pumpförmåga valdes till studien.   Resultat Utslaget över hela studiepopulationen stämde resultaten från de båda undersökningarna bra överens. Jämförde man däremot resultaten från de båda undersökningarna med varandra patient för patient förekom mycket stora variationer.   Slutsats Resultaten angående hjärtats pumpförmåga kan skilja sig mycket från varandra. Jämförelser av värden från dessa två metoder bör därför göras med väldigt stor försiktighet.
6

Gyvenimo kokybės daugiadimensis vertinimas, identifikuojant kritines sritis / Multidimensional assessment of the quality of life identifying critical areas

Servetkienė, Vaida 15 November 2013 (has links)
Disertacijoje nagrinėjama aktuali gyvenimo kokybės vertinimo problema. Mokslinėje literatūroje vis dar nėra vienodo gyvenimo kokybės suvokimo ir mokslinio apibrėžimo. Kiekvienas asmuo šiai sąvokai gali suteikti savo prasminį atspalvį, tačiau moksle gyvenimo kokybė turi būti konkrečiais rodikliais išreiškiama ir matuojama sąvoka, susijusi su visuomenės gerove konkrečioje šalyje. Šio darbo tyrimo objektas yra gyvenimo kokybės vertinimas. Disertacijos tikslas – išanalizavus mokslinius tarpdisciplininius požiūrius į gyvenimo kokybės vertinimą, parengti daugiadimensį gyvenimo kokybės vertinimo modelį ir nustatyti kritines jos sritis Lietuvoje. Darbe atlikta gyvenimo kokybės apibrėžties, koncepcijų ir praktikoje taikomų gyvenimo kokybės vertinimo metodų lyginamoji analizė, konceptualizuota gyvenimo kokybės sąvoka, ją traktuojant kaip ekonomikos mokslo tyrimo objektą, atspindintį valstybės vykdomos ekonominės politikos efektyvumą, nustatytos pagrindinės gyvenimo kokybės sritys, pateikta gyvenimo kokybės koncepcija ir pasiūlyti jos vertinimo metodologiniai principai, sudarytas daugiadimensis gyvenimo kokybės vertinimo modelis, jį taikant, įvertinta Lietuvos gyventojų gyvenimo kokybė ES šalių kontekste ir nustatytos kritinės jos sritys. / The dissertation examines the topical issue of assessment of the quality of life. Scientific literature still does not offer a uniform perception and scientific definition of the quality of life. Every person can provide this concept with his own interpretation, but in science the quality of life must be a concept expressed by means of specific indicators and measured in relation to the welfare of the population in a specific country. The object of research in this dissertation is the assessment of the quality of life. The aim of the dissertation is, upon analysing interdisciplinary scientific approaches to assessment of the quality of life, to develop a multidimensional model of assessment of the quality of life and to identify the critical areas of the quality of life in Lithuania. The author of the dissertation has carried out a comparative analysis of the definition and conceptions of the quality of life and the quality of life assessment methods employed in practice, conceptualised the concept of the quality of life treating it as an object of economic research which reflects the efficiency of the economic policy of the state, identified the key areas of the quality of life, provided a conception of the quality of life and proposed methodological principles for its assessment, developed a multidimensional quality of life assessment model and, by applying the model, evaluated the quality of life of the Lithuanian population in the context of the EU Member States and... [to full text]
7

En rekryterares bedömningsproblematik i vardagen : En fallstudie om objektiv- och subjektiv bedömning i rekryteringsprocessen

Englund, Sofia, Karlerö, Sophie January 2015 (has links)
I följande uppsats undersöker vi rekryterarens bedömningsproblematik i vardagen. Ämnet är relevant eftersom arbetsmarknaden ständigt utvecklas vilket innebär att rekryterarens objektiva bedömning har försvårats. Rekryteraren måste hitta en balansgång mellan den subjektiva och objektiva bedömningen. Studiens syfte är att undersöka rekryterarens perspektiv på och upplevelser om rekryteringsprocessen. För att få en djupare förståelse kring rekryterarnas bedömningsproblematik vid en rekrytering. Våra frågeställningar är följande: Vilken bedömningsproblematik möter rekryterare i vardagen? Hur kan rekryteraren hitta en balansgång mellan objektiv och subjektiv bedömning i rekryteringsprocessen? Utifrån vårt syfte och våra frågeställningar har vi genomfört en kvalitativ studie med semistrukturerade intervjuer. Vi har genomfört sex intervjuer med rekryterare på en offentlig verksamhet och två privata rekryteringsföretag. I denna studie utgår vi ifrån våra intervjupersoners åsikter, upplevelser och erfarenhet inom vårt ämnesområde. Empirin har transkriberats och analyserats med hjälp av en fenomenografisk analysmetod. Studiens resultat presenteras efter följande kategorier: Kravprofilen betydelse i en rekrytering, Att utföra en rättvis bedömning, Vikten av ett ärligt informationsutbyte, Bedömning av tillförlitligheten hos referenspersonerna och Hjälpmedel för objektiv bedömning. Sammanfattningsvis tyder resultatet på att rekryteraren har svårt att finna en balansgång mellan den subjektiva och objektiva bedömningen. Rekryterarna är medvetna om vilka problem som kan uppstå och kan med hjälp av deras erfarenhet finna lösningar på problemen. Problemen som uppstår vid en rekrytering skiljer sig inte emellan den offentliga verksamheten och rekryteringsföretagen. Avslutningsvis har vi diskuterat undersökningens resultat och analys utifrån våra teorier och modeller om rekrytering och bedömning.
8

Parameter Optimisation of EPAS Using CAE

Bhattacharyya, Shounak, Sivaramakrishnan, Suraj January 2019 (has links)
To keep up with technological as well as logistical challenges of the modern automobile market, major car manufacturing firms have resorted to virtual simulation tools. This enables the development as well as validation of vehicular models much before resources are invested into a new physical prototype.This project focuses on the development of a tool that would help in optimising the handling parameters of a vehicle. This is achieved by creating an optimization routine for tuning the various parameters of the Electronic Power Steering (EPAS). This process is usually done manually, by on-track testing, due to the difficulties in correlating Subjective Assessments (SA) with Objective Metrics (OM). Automating this process would help to reduce the overall research and development time, by providing a baseline tune for the EPAS parameters which could then be finely tweaked by manual track testing.The tool is built by interfacing various software in a multi-objective optimisation environment known as ModeFrontier. The modelling and simulations are performed in IPG CarMaker, with the post processing of the results taken care of by Sympathy for Data. Multiple optimization algorithms were tested to achieve the best optimisation routine. The EPAS parameters, namely the Basic Steering Torque, Active Return and Active Damping, act as the input to the optimization routine. The outputs of the model are the Objective Metrics, which provide a clear indication of the dynamic performance of a component. These metrics are optimized to _t the Steering DNA structure, which uniquely describes the attributes of a vehicle. The final optimised vehicle is manually tested at the track, to determine the real driving feel. / För att upprätthålla ett positivt momentum i såväl tekniska som logistiska utmaningar på dagens bilmarknad har stora biltillverkare börjat använda sig av virtuella simuleringsverktyg. Dessa verktyg möjliggör utveckling av diverse fordonsmodeller långt innan resurser investeras i en fysisk prototyp. Detta projekt fokuserar på utvecklingen av ett verktyg som potentiellt kan hjälpa att optimera dynamiska beteendeparametrar för ett fordon. Detta uppnås genom att skapa en optimeringsrutin för att ställa in de olika parametrarna för den elektroniska servostyrningen (EPAS). Denna process görs vanligtvis manuellt, genom test på provbana, på grund avsvårigheterna att korrelera subjektiva bedömningar (SA) med objektiva mätetal (OM). Att automatisera denna process kan bidra till att minska den övergripande forsknings- och utvecklingstiden genom att tillhandahålla en baslinje för EPAS-parametrarna som i efterhand kan finjusteras genom manuell justering på provbana. Verktyget är byggt genom att ansluta olika program i en optimeringsmiljö som kallas ModeFrontier. Modellering och simuleringar utförs i IPG CarMaker, med efterbehandling av resultaten i Sympathy for Data. Flera optimeringsalgoritmer testades för att uppnå bästa optimeringsrutinen. EPAS-parametrarna består av det grundläggande styrmomentet, aktiv retur och aktiv dämpning, och fungerar som invärden till optimeringsrutinen där utvärdera från modellen är objektiva mätetalen, vilket ger en tydlig indikation på den dynamiska prestandan hos en komponent. Dessa mätvärden optimeras för att passa Steering DNA-strukturen, som unikt beskriver egenskaperna hos ett fordon. Det slutliga optimerade fordonet testas manuellt på provbana för att bestämma den verkliga körkänslan.
9

Objective motion cueing tuning for vehicle dynamics evaluation in winter conditions

Hvitfeldt, Henrik January 2024 (has links)
Vehicle manufacturers strive for an increasingly efficient and faster development process. Although computer-aided engineering has made significant progress toward a fully virtual development process, a challenge remains in integrating human subjective feedback to fully close the virtual development loop. Subjective assessment of ride and driving characteristics are still very important traits of a passenger car. Moving-base driving simulators have the ability to introduce the human into the virtual development loop, thus enabling subjective assessment of virtual vehicle models. Such an introduction has the potential to significantly speed up the development process and at the same time save resources by avoiding physical testing and providing informed decisions in the early phase of vehicle development cycles. The challenge to do so lies in the possibility to evaluate a vehicle in a driving simulator, which is highly dependent on the motion cueing. Motion cueing algorithms are used to map the vehicle motion into the confined workspace of a driving simulator. As of today, these algorithms are still often tuned and evaluated subjectively. The challenge with this approach is that it does not guarantee the fidelity of the cueing and it needs physical vehicles to be compared with. This work thus focuses on the objective development and evaluation of motion cueing, which potentially could enable high fidelity motion cueing in the early stages of the vehicle development process, when prototypes are not available. This is very important for winter testing since the testing is challenging with regards to ambient conditions, the limited testing season and the increasing need to speed up the development process. The goal of this work is to move towards an objective approach to cueing evaluation based on physical models combining vehicle model, simulator, and human. Therefore, this thesis presents an objective methodology to motion cueing evaluation and development. Based on the state-of-the-art review, this work addresses the need for simple linear models to evaluate the fidelity of motion cueing algorithms. The linear model is applied to the problem of positioning the longitudinal axis of rotation of the simulator cabin and shows promising results when compared to time series-based optimisation and subjective assessment. Furthermore, using the same model to improve the motion cueing by introducing tilt coordination shows that even though the immersion is improved, the tilt coordination changes the perceived vehicle characteristics. To objectively evaluate different yaw cueing strategies in winter conditions, a more detailed human model is introduced that extends the state-of-the-art vestibular organ models by introducing gaze stabilisation using a model of the vestibulo-collic reflex. The cueing evaluation indicates the potential of separating slip angle feedback from the high-pass filtering of motion cues, as well as the advantage of using the vehicle’s motion as a target for cueing optimisation rather than the human vestibular response in winter handling evaluation. By addressing the inherent skewing of vehicle characteristics in motion cueing and suggesting improvements to the evaluation and cueing strategies, this work contributes to the possibility of virtually evaluating the vehicle dynamic characteristics in driving simulators under winter conditions.
10

”Vi behöver den specifika kunskapen, hur man fått den är faktiskt rätt ointressant” : En intervjustudie om validering av reell kompetens / ”We need the specific knowledge, how it is achieved is of less interest” : An Interview Study on Recognition of Prior Learning

Weinsjö, Anna, Lindh, Anders January 2016 (has links)
Den här studien syftar till att få ökad kunskap om på vilka sätt utbildningsanordnare inom yrkeshögskolan arbetar med validering av reell kompetens. Metoden som används är semistrukturerade kvalitativa intervjuer med sju personer som arbetar hos olika anordnare av yrkeshögskoleutbildningar. Med utgångspunkt i tidigare forskning om validering och olika perspektiv på kunskap, kompetens och lärande visar de viktigaste resultaten att informanterna ser reell kompetens som en möjlighet men hur informanterna synliggör den skiljer dem åt. Ett ständigt närvarande orosmoln för informanterna är att subjektiviteten påverkar tillförlitligheten vilket i sin tur påverkar rättssäkerheten i deras arbete. Studien belyser utmaningen att arbeta med validering av reell kompetens. Komplexiteten är stor vilket visar sig både i tolkning av centrala begrepp, subjektivitetens ständiga närvaro samt att informanterna efterfrågar tydliga riktlinjer och generaliserbara metoder. / The aim of this study is to increase the knowledge on how organizers of higher occupational educators work with recognition of prior learning (RPL). The method used is semi-structured interviews with seven professionals from seven different educational organizers of higher occupational education. With a starting point in earlier research and on different views on knowledge, competence and learning are the most interesting findings that the informants look upon recognition of prior learning as a possibility, but the way the informants visionalize RPL differs. An ongoing air of consciousness is how subjectivity influences the reliability, which in the next step can have a great impact of the legal rights of the individuals. The study stresses the challenge working with RPL. There is a great complexity shown in differences in interpreting central concepts and that the subjectivity is always present. The informants ask for guidelines and methods possible to generalize.

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