• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 501
  • 427
  • 114
  • 75
  • 33
  • 32
  • 31
  • 26
  • 21
  • 21
  • 10
  • 9
  • 7
  • 3
  • 2
  • Tagged with
  • 1427
  • 294
  • 269
  • 181
  • 180
  • 139
  • 137
  • 125
  • 100
  • 98
  • 93
  • 90
  • 88
  • 84
  • 84
  • 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.
171

Autonomous Filming of Test Cars : Application integration and autonomous control approach

Prasanna Bhubalan, Suriya, Dziadak, Damian January 2016 (has links)
Before vehicles that go to sale for public it goes through many stages of testing in different fields. All types of pre-production cars are the vehicles that come after prototypes which allow the OEM to find out possible issues by running different categories of tests. One of the most important fields of test is regarding safety. When it comes to autonomous cars, where safety is crucial, the number of tests to carry out, time for handling them and their complexity is increased. To reduce costs, complexity and time some of them might be simulated. After the analysis is done the cars have to be tested in real time to collect more data, not only from car sensors but also through observation from the tests filmed. This thesis contains an overview of whole project leading to develop an autonomous platform, driving after autonomous car and controlled by simulation environment and solving major issues of the project. The filming of autonomous cars remotely had two major issues. One of the issues was to integrate all the different software and platforms. The trajectories of the autonomous cars were controlled in different software and the trajectories of the RC were managed in different software. The solution to integrate all the software and platforms is shown in this thesis. The second issue was to make the RC car to follow the waypoints that are generated by simulation and by communicating with real car using a PID controller. The project is prepared for future improvements, like installing a camera to the RC car which will follow predefined test independently.
172

Dynamic simulation of a planetary gear for robots

Qin, Xiaohao, Cheng, Jiahao January 2019 (has links)
Gear drives are widely applied in mechanical transmission systems and very accurate transmission systems are needed. In the robot industry, the planetary gear train (PGT) is commonly used to promote the torque transmission. One of the advantages of an ideal PGT is that the incoming torque is divided equally among the planet gear wheels. However, different manufacturing and assembling deviations may cause uneven load distributions. This is a serious problem that affects the load capacity and the stability of the torque transmission.SwePart has designed and patented a planetary gear blazing for very high-accuracy robots and zero gaps in the gear maintained during its operating time [25]. The purpose of this project is to determine how deviations such as pitch deviation and stiffness affect the magnitude of the contact forces acting on gear teeth from the ideal geometry.In order to model the ideal geometry, an inspection of the SwePart’s gears was needed. By using SOLIDWORKS, the common normal line which is perpendicular to the teeth profiles can be defined. This means that the base circle which is tangential to that common normal line can also be found.The gear profiles of the PGTs in this study were created using the software MATLAB based on the parametric equation of involute of the base circle. The data generated by MATLAB were then used to create 3D models of the PGTs in SOLIDWORKS. The gears were split into 2N+1 parts if the number of teeth is N, since different magnitude of the pitch deviations needs to be studied. It is more informative to compare the magnitude of contact forces acting on each half tooth.When the gears which are similar to the SwePart’s gears were finished, the x_t document was exported from SOLIDWORKS and imported into MSC_ADAMS to make the simulations. After that the materials were defined in the model and contact forces were added between teeth of the planetary gear and the ring gear. The magnitude of the contact forces acting on the rigid and flexible gear teeth were then compared. So, MSC_ADAMS needs to be used to mesh the rigid bodies to the flexible ones automatically by calling MSC_Nastran.MATLAB was used to compare the results and graphs from different ADAMS models.
173

Development of an Arduino-based 3D printed 6DOF robotic phantom and a MATLAB-based software for Radiation Therapy Quality Assurance

Unknown Date (has links)
Quality Assurance (QA) for medical linear accelerators (linac) is the primary concern in external beam radiation therapy. In this research, we have developed a MATLAB-based software named Quality Assurance for Linacs (QALMA), which is unique, due to cost-effectiveness, user friendly interface, and customizability. It includes five modules to perform different QA tests: Star Shot analysis, Picket Fence test, Winston-Lutz test, MLC log file analysis, and verification of light & radiation field coincidence. We also pay attention to quality assurance of 6DOF treatment couch that plays a very important role in radiation therapy. We developed an Arduino based 3D printed 6DOF robotic phantom to check the accuracy of the treatment couch. This robotic phantom was experimentally validated under clinical standards, and customizable upon requirements of the quality assurance Task. The current features of this robotic phantom open development opportunities beyond the specific couch application, such as organs motion simulation. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2018. / FAU Electronic Theses and Dissertations Collection
174

Diseño y simulación de un scrambler digital de voz

Montoya Limón, Roberto Isaac 15 October 2012 (has links)
Un primer acercamiento a la definición de comunicación puede realizarse desde su etimología. La palabra deriva del latín communicare, que significa “compartir algo, poner en común”. Por lo tanto, la comunicación es el proceso mediante el cual el emisor y el receptor establecen una conexión en un momento y espacio determinados para compartir ideas, transmitir e intercambiar información o significados que son comprensibles para ambos. Desde un punto de vista técnico se entiende por comunicación al hecho que un determinado mensaje originado por el emisor llegue a un receptor, distante en el espacio o en el tiempo. La comunicación implica transmitir y recepcionar una determinada información que en la actualidad se encuentra muy vulnerable e insegura debido a las interceptaciones, la existencia de intereses personales, empresariales o de terceros. Este problema ha motivado la presente tesis a diseñar una alternativa de solución mediante el cual se mejora la confidencialidad de las comunicaciones que en su mayoría de casos se requiere. En tal sentido, la presente tesis tiene como objetivo presentar un Diseño y Simulación de un Scrambler Digital de Voz, el cual permitirá codificar la señal de voz a fin de transmitirla por el canal. La transmisión permitirá la comunicación exclusiva entre el emisor y receptor. Sólo el receptor podrá decodificar el mensaje y a su vez recibirá del emisor una contraseña que será establecida aleatoriamente en cada transmisión. Para la recepción, se decodificará la señal de voz con la contraseña recibida aleatoriamente garantizando de esta manera una comunicación segura. / Tesis
175

Implementación del detector de esquinas de Harris en la plataforma Jetson TK1

Chahuara Silva, Hector Francisco 27 June 2017 (has links)
Las esquinas son puntos invariantes, estructurales y con alto contenido de información en una imagen. Estas son usadas en aplicaciones importantes de Procesamiento de imágenes o video entre las cuales destacan Navegación de UAVs (Unmanned Aerial Vehicles) [1] o Detección de objetos [2] que son importantes en distintas áreas y tienen requerimientos de tiempo real. Entre las soluciones para detección de esquinas propuestas destaca el detector de esquinas de Harris [3], el cual demuestra ser robusto y eficiente. El uso de plataformas que permiten realizar procesamiento paralelo permiten implementar métodos de alto costo computacional con un bajo tiempo de procesamiento. Entre ellas destacan los GPU (Graphic Processor Unit) que generalmente tienen un alto consumo energético, lo cual es inconveniente en aplicaciones dirigidas a dispositivos móviles como celulares, robots, drones, entre otros. Por ello, plataformas basadas en mobile CPU que tienen bajo consumo energético son opciones a tomar en cuenta. En la presente tesis se propone el diseño e implementación del Detector de esquinas de Harris en la plataforma Jetson TK1 de Nvidia [4] la cual se distingue por su bajo consumo energético y alto rendimiento. El método será implementado en MATLAB, ANSI-C y CUDA. Los resultados muestran que la implementación en CUDA presentada es hasta 32.08 veces aproximadamente más rápida que la implementación en ANSI-C y permite procesar imágenes de resolución full HD (1920 x 1080) en tiempo real. Además, es comparable a implementaciones en software en plataformas con mayores recursos e implementaciones en hardware usando FPGAs (Field Programmable Gate Array). La estructura del presente documento es la siguiente: En el primer capítulo se presenta el estado del arte sobre detección de esquinas y el Detector de esquinas de Harris. En el segundo capítulo se presenta la plataforma Jetson TK1. El diseño del algoritmo paralelo se detalla en el tercer capítulo. Por último, se presenta la implementación y sus resultados en el cuarto capítulo, seguido de las conclusiones y recomendaciones. / Tesis
176

An Intelligent Portable Aerial Surveillance System: Modeling and Image Stitching

Du, Ruixiang 29 May 2013 (has links)
"Unmanned Aerial Vehicles (UAVs) have been widely used in modern warfare for surveillance, reconnaissance and even attack missions. They can provide valuable battlefield information and accomplish dangerous tasks with minimal risk of loss of lives and personal injuries. However, existing UAV systems are far from perfect to meet all possible situations. One of the most notable situations is the support for individual troops. Besides the incapability to always provide images in desired resolution, currently available systems are either too expensive for large-scale deployment or too heavy and complex for a single solder. Intelligent Portable Aerial Surveillance System (IPASS), sponsored by the Air Force Research Laboratory (AFRL), is aimed at developing a low-cost, light-weight unmanned aerial vehicle that can provide sufficient battlefield intelligence for individual troops. The main contributions of this thesis are two-fold (1) the development and verification of a model-based flight simulation for the aircraft, (2) comparison of image stitching techniques to provide a comprehensive aerial surveillance information from multiple vision. To assist with the design and control of the aircraft, dynamical models are established at different complexity levels. Simulations with these models are implemented in Matlab to study the dynamical characteristics of the aircraft. Aerial images acquired from the three onboard cameras are processed after getting the flying platform built. How a particular image is formed from a camera and the general pipeline of the feature-based image stitching method are first introduced in the thesis. To better satisfy the needs of this application, a homography-based stitching method is studied. This method can greatly reduce computation time with very little compromise in the quality of the panorama, which makes real-time video display of the surroundings on the ground station possible. By implementing both of the methods for image stitching using OpenCV, a quantitative comparison in the performance is accomplished."
177

A High Throughput Matlab Program for Automated Force-Curve Processing Using the AdG Polymer Model

O'Connor, Samantha 07 September 2014 (has links)
"Steric forces related to the lipopolysaccharide (LPS) brush on bacterial surfaces is of great importance in biofilm research. However, the atomic force microscopy (AFM) data, or force curves, produced require extensive analysis to obtain any useful information about the sample. Normally, after several force curves have been measured, the individual curves would be fit to a model for analysis. This process is not only time-consuming, but it is also extremely subjective as it lends itself to user bias throughout the analysis. A Matlab program to analyze force curves from an AFM efficiently, accurately, and with minimal user bias has been developed and is presented here. The analysis is based on a modified version of the Alexander and de Gennes (AdG) polymer model, which is a function of equilibrium polymer brush length, probe radius, temperature, separation distance, and a density variable. The program runs efficiently by cropping curves to the region specified by the model and then fitting the data. Automating the procedure reduces the amount of time required to process 100 force curves from several days to less than two minutes. Accuracy is ensured by making the program highly adjustable. The user can specify experimental constants such as the temperature and cantilever tip geometry, as well as adjust many cropping and fitting parameters to better analyze the data. Additionally, as part of this program, researchers can compare data from related experiments by choosing to plot the calculated fit parameters using either error bars or box plots to quickly identify relationships or trends. The use of this program to crop and fit force curves to the AdG model will allow researchers to ensure proper processing of large amounts of experimental data and reduce the time required for analysis and comparison of data, thereby enabling higher quality results in a shorter period of time. "
178

Temperature-Dependence of the Contact Angle of Water on Graphite, Silicon, and Gold

Osborne III, Kenneth L 29 June 2009 (has links)
"The temperature dependence of the contact angle of water on graphite, silicon and gold was investigated under various conditions to test the Sharp-Kink Approximation. Despite correctly predicting the contact angle at room temperature, the ideal Sharp-Kink Approximation was not found to accurately describe the contact angle's temperature dependence. The discrepancies from the predicted contact angle were characterized in terms of a correction H(T) to the liquid-solid surface tension. H(T) was found to be linear in temperature and decreasing, and is consistent with electrostatic charge effects."
179

Matlab Based Specific Impedance Spectroscopy Simulator for Suspension of Cells

Lagares Lemos, Miguel January 2009 (has links)
By means of the analytical formula of specific impedance for the spherical cells in suspensionintroduced by Kenneth S. Cole in 1928, a bioimpedance simulator has been developed for thegeneration of specific impedance spectrums of suspension of cells. With the help of the simulatorthe user can obtain different impedance spectrums according with the biophysical parameters ofthe cell suspension. Then, generate different kind of plots in order to understand and interpret allthe resulting information.With the selection of different values and range of the biophysical parameters to obtain thespectrums, it is possible to simulate different kinds of physiological process and observe theirelectrical bioimpedance behaviour in a certain range of frequencies. The performance of thesimulator has been validated simulating Cellular Edema and Haemorrhage has been alsosimulated.
180

Electrical Characterization of a Textile Sensor for Moisture Detection

Swaminathan, Arun, Babar Khan, Muhammad January 2011 (has links)
Electrical impedance is the frequency domain ratio of the voltage to the current. Electrical impedance extends the concept of resistance to AC circuits, describing not only the relative amplitudes of the voltage and current, but also the relative phases. Many new generation impedance measuring instruments measure the real and imaginary part of the impedance vector.Textile sensors are becoming an emerging field in industry. The possibilities that this technology holds seem almost limitless. Currently, textiles are being developed for many applications and markets, including biomedical sensing, wearable computing, large area sensors and large area actuating devices.A novel concept for a textile sensor for detection of moisture surroundings The sensor has been theoretically analysis. The results of the developed sensor shows less resistance drop characteristics against sweat.

Page generated in 0.02 seconds