• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 355
  • 178
  • 92
  • 46
  • 43
  • 24
  • 17
  • 10
  • 6
  • 5
  • 4
  • 3
  • 3
  • 3
  • 3
  • Tagged with
  • 950
  • 139
  • 116
  • 96
  • 62
  • 61
  • 60
  • 58
  • 57
  • 52
  • 51
  • 48
  • 47
  • 47
  • 44
  • 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.
311

Vehicle Dynamics Testing in Advanced DrivingSimulators Using a Single Track Model

Thellman, Jonas January 2012 (has links)
The purpose of this work is to investigate if simple vehicle models are realisticand useful in simulator environment. These simple models have been parametrisedby the Department of Electrical Engineering at Linköping University and havebeen validated with good results. The models have been implemented in a simulatorenvironment and a simulator study was made with 24 participants. Eachtest person drove both slalom and double lane change manoeuvres with the simplemodels and with VTI’s advanced model. The test persons were able to successfullycomplete double lane changes for higher velocities with the linear tyre modelcompared to both the non-linear tyre model and the advanced model. The wholestudy shows that aggressive driving of a simple vehicle model with non-linear tyredynamics is perceived to be quite similar to an advanced model. It is noted significantdifferences between the simple models and the advanced model when drivingunder normal circumstances, e.g. lack of motion cueing in the simple model suchas pitch and roll.
312

Implementation and Evaluation of a RF Receiver Architecture Using an Undersampling Track-and-Hold Circuit / Implementation och utvärdering av en RF-mottagare baserad på en undersamplande track-and-hold-krets

Dahlbäck, Magnus January 2003 (has links)
Today's radio frequency receivers for digital wireless communication are getting more and more complex. A single receiver unit should support multiple bands, have a wide bandwidth, be flexible and show good performance. To fulfil these requirements, new receiver architectures have to be developed and used. One possible alternative is the RF undersampling architecture. This thesis evaluates the RF undersampling architecture, which make use of an undersampling track-and-hold circuit with very wide bandwidth to perform direct sampling of the RF carrier before the analogue-to-digital converter. The architecture’s main advantages and drawbacks are identified and analyzed. Also, techniques and improvements to solve or reduce the main problems of the RF undersampling receiver are proposed.
313

A Simulation Analysis of an Emergency Department Fast Track System

La, Jennifer 12 1900 (has links)
The basis for this thesis involved a four month Accelerate Canada internship at the Grand River Hospital Emergency Department in Kitchener, Ontario. The Emergency Department (ED) Process Committee sought insight into strategies that could potentially reduce patient length of stay in the ED, thereby reducing wait times for emergency patients. This thesis uses discrete event simulation to model the overall system and to analyze the effect of various operational strategies within the fast track area of the emergency department. It discusses the design and development process for the simulation model, proposes various operational strategies to reduce patient wait times, and analyzes the different scenarios for an optimal fast track strategy. The main contribution of this thesis is the use of simulation to determine an optimal fast track strategy that reduces patient length of stay, thereby reducing patient wait times. Wait times were most significantly reduced when there was an increased physician presence/availability towards the fast track system. This had the greatest impact on the total time spent in the ED and also on queue length. The second most significant reduction to the performance measures occurred when an additional emergency nurse practitioner was supplemented to the fast track system. Accordingly, the nurse practitioner’s percent utilization increased. There was only one two-way interaction effect that was statistically significant in reducing the primary performance measure of wait times; however, the effect did not change the queue length, a secondary performance measure, by a significant amount. Finally, the implementation of a See-and-treat model variant for fast track had a negligible effect on both the average length of stay and queue length.
314

Distinguishing Painted dog (Lycaon pictus) footprints from Domestic dog (Canis lupus familiaris) and Hyaena (Crocuta crocuta) footprints in the field – in search of a quantitative method

Scharis, Inger January 2011 (has links)
Population estimation is an important task in all wildlife conservation. Such estimations are often difficult in low-density species such as big carnivores. The painted dog (Lycaon pictus) is an endangered species and the first aim of IUCNs action plan is to assess the size and the distribution of the remaining population. This study is the first step towards a quantitative method to distinguish painted dog footprints from footprints of feral domestic dogs and hyaenas. Footprint photographs were collected and digitally processed and total pad area and angles between the digits and backpad of the paw were measured. Both the pad area and the angles show a statistically significant difference between the species. However, further analysis shows that there is no significant difference in pad area between painted dog females and domestic dog males. Size of the pads alone is therefore not suitable as a measure to determine the species from an unknown footprint. The angles between backpad and digits seem to be more suitable to distinguish between species. Therefore, a combination of pad size and the angle between backpad and digits might be useful to estimate the species from an unknown footprint in the field.
315

The Study of Synthetic Aperture Sonar System: Analysis of Range Resolution

Chang, Tzu-hsuan 28 July 2011 (has links)
The basic principle in SAS is to use an array which is small in length to create a long synthetic array thus the better resolution is achieved through the use of signal processing. Additionally, the resolution that is independent of range and signal frequency, makes SAS a advantageous tool for applications. Although the origin of SAS comes from SAR, SAS still needs to overcome all constraints for real-world application. In a previous study by Sung and prof. Liu, published results of the along track resolution experiments which were well done however there was still much room in range resolution, the purpose of this research is to achieve high range resolution at any ranges. Indeed there are many existing factors affecting the capability of resolution which including characteristic of the target, certain arrangements of targets, bandwidth, waveforms and pulse duration and etc. High range resolution is obtained using pulse compression techniques. The experiments were carried out using the transducers of AST MK VI 192 kHz which were employed to transmit and receive signals, scanned various copper balls at anechoic water tank(4 m ¡Ñ 3.5 m ¡Ñ 2 m) in NSYSU. From the equipment we have now results were evaluated based on both simulated and real data: for the range resolution the pulse length is very important the shortest pulse length on an object would be 2L/c theoretically, the measured range resolution is about 7.5 cm for the 20-kHz bandwidth signals and 5 cm for along track resolution. As all the experiments have been successful in the Water Tank, we intent to launch further investigation of this research to the real world application of SAS i.e. in Sizihwan Bay Marine Test Field.
316

A Study on How On-line Games Affect the Interaction Between

Yen, Rong-Horng 08 August 2006 (has links)
When we probe into how on-line games affect the interaction between teenagers and their families, we find that the parents¡¦ teaching attitude is the key factor of affecting the children¡¦s behavior in the games. If the parents and the children have a better interaction, or even they can play the games together, then the development of the children are comparatively healthier and better. From the analysis of this study, we see that on-line games did not bring about bad effects to the children, on the contrary, under the guidance of the parents, the children can successfully go in and out the world of on-line games. Such an unharmed result is just what most of the parents like to see: not to indulge, not to be deceived, not to contract bad habits from bad friends and so on. However, comparatively, the children¡¦s experience in on-line games could lack spirit of adventure. No matter in a fictitious or a concrete society, the grownups have a higher capacity of awakening after all. The guidance of the parents can inspire unlimited possibilities in the children, and they can ward off the chance of getting hurt under the parents¡¦ protection. ¡§Defeat is the motivation of growth; deception is the turning point of development!¡¨ Don¡¦t forget to reserve the room for defeat during the process of children guidance and assistance. When the grownups shake off the self-centered and subjective viewpoints, they are conscious of a transformation of a hero. In the fictitious world, making a mistake is a rare chance to launch an unexpected discovery, and life starts to liaise the unknown power. Regardless of old or young, and which life stage you are at, conjuration can always unveil the overture of mythic transformation. When you fulfill a spiritual trial and ritual, it is like you are experiencing a circle of death and resurrection. Experiences are past concepts and modes of thinking in a familiar living domain which are applicative no more, and it is time to cross the threshold. After returning I hope to provide some corresponded and balanced viewpoints to the past one-way discourse, and let the teenagers to show more distinctive features of themselves.
317

Detection And Tracking Of Dim Signals For Underwater Applications

Sengun Ermeydan, Esra 01 July 2010 (has links) (PDF)
Detection and tracking of signals used in sonar applications in noisy environment is the focus of this thesis. We have concentrated on the low Signal-to-Noise Ratio (SNR) case where the conventional detection methods are not applicable. Furthermore, it is assumed that the duty cycle is relatively low. In the problem that is of concern the carrier frequency, pulse repetition interval (PRI) and the existence of the signal are not known. The unknown character of PRI makes the problem challenging since it means that the signal exists at some unknown intervals. A recursive, Bayesian track-before-detect (TBD) filter using particle filter based methods is proposed to solve the concerned problem. The data used by the particle filter is the magnitude of a complex spectrum in complex Gaussian noise. The existence variable is added in the design of the filter to determine the existence of the signal. The evolution of the signal state is modeled by a linear stochastic process. The filter estimates the signal state including the carrier frequency and PRI. Simulations are done under different scenarios where the carrier frequency, PRI and the existence of the signal varies. The results demonstrate that the algorithm presented in this thesis can detect signals which cannot be detected by conventional methods. Besides detection, the tracking performance of the filter is satisfying.
318

Particle Filter Based Track Before Detect Algorithm For Tracking Of Dim Moving Targets

Sabuncu, Murat 01 February 2012 (has links) (PDF)
In this study Track Before Detect (TBD) approach will be analysed for tracking of dim moving targets. First, a radar setup is presented in order to introduce the radar range equation and signal models. Then, preliminary information is given about particle filters. As the main algorithm of this thesis, a multi-model particle filter method is developed in order to solve the non-linear non-Gaussian Bayesian estimation problem. Probability of target existence and RMS estimation accuracy are defined as the performance parameters of the algorithm for very low SNR targets. Simulation results are provided and performance analysis is presented as a conclusion.
319

Nonuniform Distribution of Molecularly Thin Lubricant Caused by Inhomogeneous Buried Layers of Discrete Track Media

Fukuzawa, Kenji, 福澤, 健二, Muramatsu, Takuro, Amakawa, Hiroaki, Itoh, Shintaro, Zhang, Hedong 11 1900 (has links)
No description available.
320

Development of A Sun Track Solar Energy System with Artificial Intelligence

Lay, Jong-Jinn 24 June 2008 (has links)
Factors of very rapidly rising oil prices, the running out time limits on continued use of fossil fuels, as well as elements of the Kyoto Protocol, have greatly arouses the increasing emphasis on natural and renewable energy sources. 40 minutes of total solar radiation on earth could provide enough power to meet the energy needs of all human beings for approximately one year. The potential of solar energy is virtually limitedless. Moreover, by means of solar powered batteries, solar energy can be directly converted to electric power. Since it neither pollutes the environment or ecology, solar is an extremely clean source of energy. The life-span of solar cell is very long, possibly 20 years or more. The capability of solar batteries to provide energy is approximately proportional to the intensity of the sunlight. This thesis proposes the use of Artificial intelligence for "Sun Track Solar Energy System". This system employs Fuzzy Logic Control Theory, combined with Grey Relational Analysis, for tracking the angle of the sun, and further control the motor to adjust the angle for tracking, so direct sunlight could be acquired to increase power output. As a result of the experiment, comparing the electricity generated from the fix angle solar battery with the AI-based Sun Track Solar Energy System, the latter one has an efficiency increase up to 23% for the same amount of sunlight.

Page generated in 0.0316 seconds