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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.
481

Sales performance : A study of the correlation between personality traits and sales performance in the Swedish car dealership market.

Andersson, Johan, Carlson, Adam, Monié, Robert January 2015 (has links)
Background: When a company is employing new salespeople, much is expected from these. The company is hoping that the new candidate is going to perform well and contribute to the fullest. One of the big questions that the organization has to face is how to evaluate and sift through sales candidates in order to find the best suited one. Previous studies have shown to some extent that a person's personality can be connected to how well they are performing in different occupations. One commonly used framework for assessing personality is the Five Factor Model (FFM) which is able to account for different traits without overlapping. One way to assess a person's personality traits is by the use of the big five inventory questionnaire (BFI). Purpose: To describe if there is a correlation between personality traits and sales performance in the Swedish car dealership market.Method: The research was a quantitative study of two Swedish car dealerships, where 60 out of 72 employees at Hedin Bil & Holmgrens Bil answered the BFI questionnaire. The response rate was 83%. The survey was sent out by mail to the two companies whose responsible managers divided their sales staff in three different groups (good performing, average performing and bad performing) according to the company's organizational goals.Conclusion: The conclusion of this study is that one of the hypotheses was supported and four rejected by the salespeople participating. The only hypothesis that was supported was that Neuroticism would correlate negatively with sales performance.
482

För gammal för att köra bil? : En kostnadsnyttoanalys om Sverige bör införa körkortskontroller för bilförare över 75 år / Too old to drive? : A cost-benefit analysis whether Sweden should introduce license controls for older drivers

Engfeldt, Elin January 2014 (has links)
Varje år ökar antalet äldre personer och i samband med den ökningen blir även antalet äldre personer med körkort allt fler. Med åldern är det vanligt att reaktionsförmåga, syn och hörsel försämras vilka alla är viktiga egenskaper för trafiksäkerheten. Läkare i Sverige är skyldiga att rapportera till Transportstyrelsen om en individ inte anses vara lämplig att köra bil. Att läkare över huvud taget tar upp körkortsfrågan med sina patienter sker endast i 60 procent av fallen och därmed fortsätter många olämpliga körkortsinnehavare att köra bil. Majoriteten av länder inom Europeiska Unionen (EU) har någon form av övre åldersbegränsning i körkorten där körkortsinnehavarna måste genomgå en kontroll för att få körkortet förnyat. Det är endast Sverige och sex andra länder inom EU som inte har någon form av körkortskontroll för äldre och i denna studie kommer en kostnadsnyttoanalys utformas för att ta reda på om kontroller för körkortsinnehavare över 75 år skulle reducera antalet döda och skadade i trafikolyckor och därmed vara samhällsekonomiskt lönsamt. De länder som tillämpar körkortskontroller har olika bestämmelser hur metoderna är utformade och studien tar upp hur det fungerar i några av länderna. Vidare redovisas forskning inom området och resultatet av undersökningar av olika testmetoder. Merparten av forskningsresultaten visar att körkortskontroller inte har någon större effekt på trafiksäkerheten och det går inte med säkerhet att säga hur många liv som räddas och antal skadade som skulle kunna reduceras genom införandet av tester. Därmed har dessa siffror fått antagits utan att ha något säkert underlag och utifrån denna antagning visar kostnadsnyttoanalysen att införandet av körkortskontroller inte skulle generera välfärd i Sverige. Utifrån resultatet går det att dra slutsatsen att Sverige har gjort en god bedömning om att endast ha anmälningsplikt för läkare förutsatt att den följs bättre. Även om resultatet visar att kontroller för personer över 75 år inte ska införas bör ändå trafiksäkerheten för äldre utvecklas genom att till exempel förenkla körningen vid vänstersvängar och förbättra kollektivtrafiken. / The numbers of elderly increase every year and the amount of older people with a license will increase as well. When getting older, it is natural that the reaction time, hearing and vision will change and these are all important features for traffic safety. Doctors in Sweden are required to report to the Swedish Transport Agency if an individual does not seem appropriate to drive. It is not common that doctors ask their patients about their physical health and ability to drive, the questions are only asked in about 60 percent of the physical evaluations and because of that, inappropriate license holders may proceed to use a vehicle. The majority of countries within the European Union embrace some kind of upper age limit to provide drivers with a valid license and several countries have compulsory medical examinations for license holders at a certain age. It is only Sweden together with six other EU countries that does not provide any license controls for elderly and in this study a cost benefit analysis is designed to determine whether controls for drivers over the age of 75 would reduce deaths and injuries caused by traffic accidents and thus increase welfare. The countries that apply driving license controls have different rules how the controls are designed and the study presents how it works in some of the countries. Further, research within the area shows that license controls does not have any sufficient effect on traffic safety. It cannot with certainty be said how many lives are saved and the amount injuries that could be reduced by an introduction of these tests. Thus, these numbers are adopted without any sufficient evidence and from this an assumption of the cost benefit analysis will show that an introduction of license controls would not generate a welfare increase in Sweden. Based on the result it is possible to conclude that Sweden has made a good assessment to have only a reporting requirement for physicians but the reports must be stricter. Although the result shows that license controls for people over the age of 75 should not be imposed, nevertheless traffic safety for elderly should be further developed, for example with simplifying left turns and improve public transportation.
483

Bayesian analysis for time series of count data

2014 July 1900 (has links)
Time series involving count data are present in a wide variety of applications. In many applications, the observed counts are usually small and dependent. Failure to take these facts into account can lead to misleading inferences and may detect false relationships. To tackle such issues, a Poisson parameter-driven model is assumed for the time series at hand. This model can account for the time dependence between observations through introducing an autoregressive latent process. In this thesis, we consider Bayesian approaches for estimating the Poisson parameter-driven model. The main challenge is that the likelihood function for the observed counts involves a high dimensional integral after integrating out the latent variables. The main contributions of this thesis are threefold. First, I develop a new single-move (SM) Markov chain Monte Carlo (MCMC) method to sample the latent variables one by one. Second, I adopt the idea of the particle Gibbs sampler (PGS) method \citep{andrieu} into our model setting and compare its performance with the SM method. Third, I consider Bayesian composite likelihood methods and compare three different adjustment methods with the unadjusted method and the SM method. The comparisons provide a practical guide to what method to use. We conduct simulation studies to compare the latter two methods with the SM method. We conclude that the SM method outperforms the PGS method for small sample size, while they perform almost the same for large sample size. However, the SM method is much faster than the PGS method. The adjusted Bayesian composite methods provide closer results to the SM than the unadjusted one. The PGS and the selected adjustment method from simulation studies are compared with the SM method via a real data example. Similar results are obtained: first, the PGS method provides results very close to those of the SM method. Second, the adjusted composite likelihood methods provide closer results to the SM than the unadjusted one.
484

Simulation of Surrounding Vehicles in Driving Simulators

Olstam, Johan January 2009 (has links)
Driving simulators and microscopic traffic simulation are important tools for making evaluations of driving and traffic. A driving simulator is de-signed to imitate real driving and is used to conduct experiments on driver behavior. Traffic simulation is commonly used to evaluate the quality of service of different infrastructure designs. This thesis considers a different application of traffic simulation, namely the simulation of surrounding vehicles in driving simulators. The surrounding traffic is one of several factors that influence a driver's mental load and ability to drive a vehicle. The representation of the surrounding vehicles in a driving simulator plays an important role in the striving to create an illusion of real driving. If the illusion of real driving is not good enough, there is an risk that drivers will behave differently than in real world driving, implying that the results and conclusions reached from simulations may not be transferable to real driving. This thesis has two main objectives. The first objective is to develop a model for generating and simulating autonomous surrounding vehicles in a driving simulator. The approach used by the model developed is to only simulate the closest area of the driving simulator vehicle. This area is divided into one inner region and two outer regions. Vehicles in the inner region are simulated according to a microscopic model which includes sub-models for driving behavior, while vehicles in the outer regions are updated according to a less time-consuming mesoscopic model. The second objective is to develop an algorithm for combining autonomous vehicles and controlled events. Driving simulators are often used to study situations that rarely occur in the real traffic system. In order to create the same situations for each subject, the behavior of the surrounding vehicles has traditionally been strictly controlled. This often leads to less realistic surrounding traffic. The algorithm developed makes it possible to use autonomous traffic between the predefined controlled situations, and thereby get both realistic traffc and controlled events. The model and the algorithm developed have been implemented and tested in the VTI driving simulator with promising results.
485

Modeling survival after acute myocardial infarction using accelerated failure time models and space varying regression

Yang, Aijun 27 August 2009 (has links)
Acute Myocardial Infarction (AMI), commonly known as heart attack, is a leading cause of death for adult men and women in the world. Studying mortality after AMI is therefore an important problem in epidemiology. This thesis develops statistical methodology for examining geographic patterns in mortality following AMI. Specifically, we develop parametric Accelerated Failure Time (AFT) models for censored survival data, where space-varying regression is used to investigate spatial patterns of mortality after AMI. In addition to important covariates such as age and gender, the regression models proposed here also incorporate spatial random e ects that describe the residual heterogeneity associated with di erent local health geographical units. We conduct model inference under a hierarchical Bayesian modeling framework using Markov Chain Monte Carlo algorithms for implementation. We compare an array of models and address the goodness-of- t of the parametric AFT model through simulation studies and an application to a longitudinal AMI study in Quebec. The application of our AFT model to the Quebec AMI data yields interesting ndings concerning aspects of AMI, including spatial variability. This example serves as a strong case for considering the parametric AFT model developed here as a useful tool for the analysis of spatially correlated survival data.
486

Designing and simulating a Car2X communication system using the example of an intelligent traffic sign

Shil, Manash 03 March 2015 (has links) (PDF)
The thesis with the title “Designing and simulating a Car2X communication system using the example of an intelligent traffic sign” has been done in Chemnitz University of Technology in the faculty of Computer Science. The purpose of this thesis is to define a layered architecture for Infrastructure to Vehicle (I2V) communication and the implementation of a sample intelligent traffic sign (variable speed limit) application for a Car2X communication system. The layered architecture of this thesis is defined based on three related projects. The application is implemented using the defined layered architecture. Considering the availability of hardware, the implementation is done using the network simulator OMNET++. To check the feasibility of the application three scenarios are created and integrated with the application. The evaluation is done based on the result log files of the simulation which show that the achieved results conform with the expected results, except some minor limitations.
487

再配車を用いない複数ステーション型自動車共同利用システムの挙動に関するシミュレーション分析

山本, 俊行, YAMAMOTO, Toshiyuki, 中山, 晶一朗, NAKAYAMA, Shoichiro, 北村, 隆一, KITAMURA, Ryuichi 04 1900 (has links)
No description available.
488

Driver Modeling Based on Driving Behavior and Its Evaluation in Driver Identification

Miyajima, Chiyomi, Nishiwaki, Yoshihiro, Ozawa, Koji, Wakita, Toshihiro, Itou, Katsunobu, Takeda, Kazuya, Itakura, Fumitada January 2007 (has links)
No description available.
489

Threshold photo-ionisation and density functional theory studies of metal-carbide clusters.

Dryza, Viktoras January 2008 (has links)
Neutral gas-phase metal-carbide clusters are generated by laser ablation and are detected in the constructed time-of-flight mass-spectrometer by laser ionisation. Photo-ionisation efficiency (PIE) experiments are performed on the metal-carbide clusters to determine their ionisation potentials (IPs). Complimentary density functional theory (DFT) calculations are performed on the energetically favorable structural isomers of the metalcarbide clusters. Comparison between the calculated IPs of the isomers and the experimental IP allows the carrier of the observed ionisation onset for a metal-carbide cluster to be assigned. The niobium-carbide clusters Nb₃Cy (y = 0–4), Nb₄Cy (y = 0–6) and Nb₅Cy (y = 0–6) are examined by PIE experiments and DFT calculations. The IPs of the niobium-carbide clusters are found to be either left reasonably unchanged from the IPs of the bare metal clusters or moderately reduced. The clusters Nb₃C₂, Nb₄C₄, Nb₅C₂ and Nb₅C₃ display the largest IP reductions for their corresponding cluster series. The structures assigned to the IPs of the Nb₃Cy (y = 1–3) clusters are based on the carbon atoms attaching to the niobium faces and/or niobium-niobium edges of the triangular Nb₃ cluster. However, for Nb₃C₄ the ionisation onset is assigned to a low-lying isomer, which contains a molecular C₂ unit, rather than the lowest energy isomer, a niobium atom deficient 2×2×2 face-centred cubic (fcc) nanocrystal structure. The structures assigned to the IPs of the Nb₄Cy (y = 1–4) clusters are based on the carbon atoms attaching in turn to the niobium faces of the tetrahedral Nb₄ cluster, developing a 2×2×2 fcc nanocrystal structure for Nb₄C₄. For Nb₄C₃ two ionisation onsets are observed; one weak onset at low energy and another more intense onset at high energy. It is proposed that the two onsets are due to ionisation from both a metastable ³A₁ state and the ground ¹A₁ state of the lowest energy isomer. The ionisation onsets of Nb₄C₅ and Nb₄C₆ are also proposed to originate from metastable triplet states of the lowest energy isomers, with the transitions from the ground singlet states calculated to be greater than the highest achievable photon energy in the laboratory. The structures of Nb₄C₅ and Nb₄C₆ have one and two carbon atoms in a 2×2×2 fcc nanocrystal substituted with molecular C₂ units, respectively. The structures assigned to the IPs of the Nb₅Cy (y = 1–6) clusters are based on the underlying Nb₅ cluster being in either a “prolate” or “oblate” trigonal bipyramid geometry; the former has six niobium faces available for carbon addition, while the latter has two niobium butterfly motifs and two niobium faces available for carbon addition. Both the structures of Nb₅C₅ and Nb₅C₆ have the underlying Nb₅ cluster in the oblate trigonal bipyramid geometry and contain one and two molecular C₂ units, respectively. The tantalum-carbide clusters Ta₃Cy (y = 0–3), Ta₄Cy (y = 0–4) and Ta₅Cy (y = 0–6) are examined by PIE experiments and DFT calculations. The IPs of the tantalum-carbide clusters in each series show trends that are very similar to the corresponding iso-valent niobium-carbide cluster series, although the IP reductions upon carbon addition are smaller for the former. For the vast majority of tantalum-carbide clusters, the same structural isomer is assigned to the ionisation onset as that assigned for the corresponding niobium-carbide cluster. Bimetallic tantalum-zirconium-carbide clusters are generated using a constructed double ablation cluster source. The Ta₃ZrCy (y = 0–4) clusters are examined by PIE experiments and DFT calculations. The IP trend for the Ta₃ZrCy cluster series is reasonably similar to that of the Ta₄Cy cluster series, although the IP reductions upon carbon addition are greater for the former. The structures assigned to the IPs of the Ta₃ZrCy (y = 1–4) clusters are based on the carbon atoms attaching in turn to the metal faces of the tetrahedral Ta₃Zr cluster. In summary, the work presented in this thesis demonstrates that the structures of metalcarbide clusters can be inferred by the determination of their IPs through PIE experiments in combination with DFT calculations on candidate structural isomers. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1347219 / Thesis (Ph.D.) - University of Adelaide, School of Chemistry and Physics, 2008
490

Assessment and reduction of the impacts of large freight vehicles on urban traffic corridor performance

Ramsay, Euan Douglas January 2007 (has links)
Increasing demand for road freight has lead to a widespread adoption of more-productive large freight vehicles (LFVs), such as B-Doubles, by Australia's road freight industry. Individual LFVs have a greater potential to impact traffic efficiency through their greater length and poorer longitudinal performance. However, this is offset to an extent as fewer vehicles are required to perform a given freight task on a tonne-km basis. This research has developed a means of characterising the effects that large freight vehicles have on the performance of an urban arterial corridor managed by signalised intersections. A corridor-level microsimulation model was developed from first principles, which modelled the longitudinal performance of individual vehicles to a greater accuracy than most existing traffic simulation software does. The model was calibrated from traffic counts and GPS-equipped chase car surveys conducted on an urban arterial corridor in Brisbane's southern suburbs. The model was applied to various freight policy and traffic management scenarios, including freight vehicle mode choice, lane utilisation and traffic signal settings; as well as the effectiveness of green time extension for approaching heavy vehicles. Benefits were able to be quantified in terms of reduced travel times and stop rates for both heavy and light vehicles in urban arterial corridors.

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