• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 231
  • 94
  • 40
  • 38
  • 19
  • 8
  • 5
  • 5
  • 5
  • 5
  • 4
  • 4
  • 4
  • 4
  • 3
  • Tagged with
  • 535
  • 97
  • 60
  • 51
  • 50
  • 49
  • 42
  • 40
  • 37
  • 37
  • 36
  • 36
  • 34
  • 33
  • 33
  • 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.
121

Airborne mapping using LIDAR / Luftburen kartering med LIDAR

Almqvist, Erik January 2010 (has links)
Mapping is a central and common task in robotics research. Building an accurate map without human assistance provides several applications such as space missions, search and rescue, surveillance and can be used in dangerous areas. One application for robotic mapping is to measure changes in terrain volume. In Sweden there are over a hundred landfills that are regulated by laws that says that the growth of the landfill has to be measured at least once a year. In this thesis, a preliminary study of methods for measuring terrain volume by the use of an Unmanned Aerial Vehicle (UAV) and a Light Detection And Ranging (LIDAR) sensor is done. Different techniques are tested, including data merging strategies and regression techniques by the use of Gaussian Processes. In the absence of real flight scenario data, an industrial robot has been used fordata acquisition. The result of the experiment was successful in measuring thevolume difference between scenarios in relation to the resolution of the LIDAR. However, for more accurate volume measurements and better evaluation of the algorithms, a better LIDAR is needed. / Kartering är ett centralt och vanligt förekommande problem inom robotik. Att bygga en korrekt karta av en robots omgivning utan mänsklig hjälp har en mängd tänkbara användningsområden. Exempel på sådana är rymduppdrag, räddningsoperationer,övervakning och användning i områden som är farliga för människor. En tillämpning för robotkartering är att mäta volymökning hos terräng över tiden. I Sverige finns det över hundra soptippar, och dessa soptippar är reglerade av lagar som säger att man måste mäta soptippens volymökning minst en gång om året. I detta exjobb görs en undersökning av möjligheterna att göra dessa volymberäkningarmed hjälp av obemannade helikoptrar utrustade med en Light Detectionand Ranging (LIDAR) sensor. Olika tekniker har testats, både tekniker som slår ihop LIDAR data till en karta och regressionstekniker baserade på Gauss Processer. I avsaknad av data inspelad med riktig helikopter har ett experiment med en industri robot genomförts för att samla in data. Resultaten av volymmätningarnavar goda i förhållande till LIDAR-sensorns upplösning. För att få bättre volymmätningaroch bättre utvärderingar av de olika algoritmerna är en bättre LIDAR-sensor nödvändig.
122

NAVET's Boxes - an Evaluation of the Post-Visit Loan Service at a Science Centre in Borås

Göthberg, Renée January 2005 (has links)
Many pedagogues believe science centres to be a good complement to the more formal school teaching. For a visit to a science centre to be as educational as possible, there is a need for pre-visit information of some sort, a guided visit, and post-visit work. Many science centres offer loan services of different kinds. At Navet, a science centre in Borås, teachers can borrow boxes with experiments connected to the different themes they provide. The experiments are supposed to be a continuation of the visit and help settle the knowledge gained during the visit. This thesis is an evaluation of how the boxes function in the schools, and what the teachers think of them. The study was conducted through questionnaires and interviews with both teachers and the staff at Navet. The results of the study are very positive. Many teachers have been involved with Navet from the very beginning and they see a visit to Navet as an integrated part of their teaching. Some boxes work better than others and some might need clearer information, but overall the teachers see the boxes as timesavers, as a way to vary their teaching more easily, and as a help for teachers not specialized in mathematics and science.
123

Locating and tracking assets using RFID

Kim, Gak Gyu 15 May 2009 (has links)
Being able to quickly locate equipment is critical inside buildings, including hospitals, manufacturing floors and warehouses. In order to utilize limited budget and resources efficiently, accurate locating or tracking is required in many fields. In this research, we will focus on how to find the location of an item by using RFID in real time indoors to track equipment. When an item needs to be located, the purpose of using RFID is to minimize the searching time, effort, and investment cost. Thus, this research presents a math¬ematical model of using RFID (both handheld readers and stationary readers) for efficient asset location. We derive the expected cost of locating RFID¬tagged objects in a multi¬area environment where hand¬held RF readers are used. We then discuss where to deploy stationary RF readers in order to maximize the efficiency of the search process.
124

Verification And Matlab Implementation Of The Inverse Dynamics Model Of The Metu Gait Analysis System

Erer, Koray Savas 01 June 2008 (has links) (PDF)
The METU Gait Analysis System employs a computer program called Kiss-GAIT for the calculation of joint angles, moments and powers using force plate data and marker trajectories as input. Kiss-GAIT was developed using Delphi and is confined to calculations related to the standard gait protocol. Because the code lacks the flexibility required to carry out various test cases, the inverse dynamics formulation being used could not be verified and the extent of the error propagation problem could not be determined so far. The first aim of this study was to develop a code for the inverse dynamics model of the METU Gait Analysis System making use of the flexible programming environment provided by MATLAB. Verified and more reliable analysis results, obtained by reformulating the inverse dynamics algorithm in a new code, are presented. Secondly, data smoothing and differentiation techniques conventionally used in gait analysis were critically reviewed. A common tool used for filtering marker trajectories is the Butterworth digital filter. This thesis presents a modified, adaptive version of this classical tool that can handle non-stationary signals owing to its coefficients which are functions of local signal structure. The results of this thesis indicate the dominancy of ground reactions as compared to inertial effects in normal human gait. This implies that the accuracy needed in body segment inertial parameter estimation is not a critical factor. On the other hand, marker trajectories must be as accurate as possible for meaningful kinetic patterns. While any smoothing and differentiation routine that produces reasonable estimates is sufficient for joint moment calculation purposes, the estimation performance becomes a key requirement for the calculation of joint powers.
125

Fiscal Deficits, Debts Financing, and Interest Rates in Taiwan: The Empirical Analysis of Cointegration

Huang, Jung-chih 17 August 2008 (has links)
Standard and Poor¡¦s (S & P), a global leading corporation in providing credit rating, published the sovereign rating outlook of Taiwan which was ¡§negative sign¡¨ at the end of 2007. The main reason was that the situation of public finance continued worsening. Based on traditional economic theory, the increased deficits or debts led to higher interest rates, and the increasing burden on enterprises for paying more loan cost, would have more adverse effects on the domestic investment activities. Therefore, this study is intended to explore the relationships among the long-term interest rates of public bonds, the outstanding debts, fiscal deficits, and government expenditure in Taiwan by analyzing 53 seasonal data from 1994:4 to 2007:4 as the samples. The findings indicate that no structure breaking points exist in every variable by using CUSUM test, and almost every variable is integrated of order one in unit root test. The results also reveal that there is no long-term relationship among the deficits, government expenditure, and interest rates using the cointegration analysis. There are probably two reasons for explanation: one is that people will increase saving automatically, and another is that the increased interest rates in the tax cut may be offset by the decreased interest rates in debts financing. Moreover, the outstanding debts and interest rates exist a significant negative relationship of long-term equivalence, and further variance decomposition shows that the effect of debts on interest rates is higher than the effect of interest rates on debts in the variable¡¦s explanatory ability. To explain the significant negative relationship, the possible main causes are liquidity factor, and the psychological anticipation of saving in public bond form directly or indirectly; the secondary cause is the fluctuation of interest rates affects the willingness of government financing.
126

Modeling and Control of Non-contacting Steel Plate Conveyance System

Lin, Sheng-Yang 25 August 2009 (has links)
A non-contacting steel plate conveyance system based on the linear induction motor scheme, which can provide lift and propulsive forces simultaneously, is proposed. It has the features of high power density, direct drive, simple mechanical structure, and being able to reduce the operation noise. A magnetic equivalent circuit method and electromagnetic theory incorporating with 3-D finite element analysis are involved to investigate the static and quasi-dynamic properties and confirm the electrical and mechanical designs. To realize the dynamic behavior and develop the closed-loop control, a proper stationary reference frame transformation of the system voltage equations is also introduced. By considering the practical operational environment, a fuzzy-based control structure integrated with remote optical measurement system has been established and implemented by a DSP-based controller combined with required peripheral circuits. The experimental results show the applicability of such control strategies. With the systematic procedures for design, analysis, and control provided in this dissertation, implementation feasibility of the proposed system can be conveniently demonstrated.
127

Asymptotic Expansions for Second-Order Moments of Integral Functionals of Weakly Correlated Random Functions

Scheidt, Jrgen vom, Starkloff, Hans-Jrg, Wunderlich, Ralf 30 October 1998 (has links) (PDF)
In the paper asymptotic expansions for second-order moments of integral functionals of a class of random functions are considered. The random functions are assumed to be $\epsilon$-correlated, i.e. the values are not correlated excluding a $\epsilon$-neighbourhood of each point. The asymptotic expansions are derived for $\epsilon \to 0$. With the help of a special weak assumption there are found easier expansions as in the case of general weakly correlated functions.
128

Moving-Average approximations of random epsilon-correlated processes

Kandler, Anne, Richter, Matthias, vom Scheidt, Jürgen, Starkloff, Hans-Jörg, Wunderlich, Ralf 31 August 2004 (has links) (PDF)
The paper considers approximations of time-continuous epsilon-correlated random processes by interpolation of time-discrete Moving-Average processes. These approximations are helpful for Monte-Carlo simulations of the response of systems containing random parameters described by epsilon-correlated processes. The paper focuses on the approximation of stationary epsilon-correlated processes with a prescribed correlation function. Numerical results are presented.
129

On the convergence of random functions defined by interpolation

Starkloff, Hans-Jörg, Richter, Matthias, vom Scheidt, Jürgen, Wunderlich, Ralf 31 August 2004 (has links) (PDF)
In the paper we study sequences of random functions which are defined by some interpolation procedures for a given random function. We investigate the problem in what sense and under which conditions the sequences converge to the prescribed random function. Sufficient conditions for convergence of moment characteristics, of finite dimensional distributions and for weak convergence of distributions in spaces of continuous functions are given. The treatment of such questions is stimulated by an investigation of Monte Carlo simulation procedures for certain classes of random functions. In an appendix basic facts concerning weak convergence of probability measures in metric spaces are summarized.
130

Αφαίρεση θορύβου από ψηφιακές εικόνες μικροσυστοιχιών DNA

Καπρινιώτης, Αχιλλέας 18 June 2009 (has links)
Στο πείραμα των μικροσυστοιχιών, η απόκτηση εικόνας συνοδεύεται πάντα από θόρυβο, ο οποίος είναι έμφυτος σε τέτοιου είδους διεργασίες. Είναι λοιπόν επιτακτική ανάγκη να χρησιμοποιηθούν τεχνικές προς καταστολή αυτού. Στην παρούσα εργασία αναλύονται μέθοδοι και παρουσιάζονται τα αποτελέσματά τους σε 5 επιλεγμένα παραδείγματα. Ιδιαίτερη έμφαση δίνεται στο wavelet denoising και συγκεκριμένα στους αλγορίθμους soft thresholding, hard thresholding και stationary wavelet transform. / The subject of this diploma thesis is the manufacturing of a driver assistance system. Robust and reliable vehicle detection from images acquired by a moving vehicle (i.e., on road vehicle detection) is an important problem with applications to driver assistance systems and autonomous, self-guided vehicles. The focus of this diploma is on the issues of feature extraction and classification for rear-view vehicle detection. Specifically, by treating the problem of vehicle detection as a two-class classification problem, we have investigated several different feature extraction methods such as wavelets and Gabor filters. To evaluate the extracted features, we have experimented with two popular classifiers, neural networks and support vector machines (SVMs).

Page generated in 0.1025 seconds