• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 284
  • 278
  • 216
  • 63
  • 59
  • 34
  • 15
  • 14
  • 11
  • 11
  • 10
  • 10
  • 5
  • 5
  • 3
  • Tagged with
  • 1210
  • 186
  • 183
  • 181
  • 171
  • 170
  • 168
  • 160
  • 159
  • 157
  • 154
  • 152
  • 150
  • 149
  • 147
  • 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.
91

Bore Waviness Measurement Using an In-Process Gage

Krueger, Kristian Wolfgang 28 November 2005 (has links)
Profile waviness is one of the main causes for scrapped parts in precision bore grinding. Although efforts have been made to reduce its occurrence, the problem has not been eliminated completely. In production, the identification of a few scrapped parts in a lot of several thousands often requires expensive manual processes. Grinding machines used to produce these parts are usually equipped with measurement gage heads having tactile probes. Until now, these in-process gages have been used to measure only the average diameter of the part. This research focused on the use of these tactile probes to measure bore waviness in precision-ground parts. The first objective was to develop a post-process machine that performs automated measurement of the bore profile and is capable of detecting waviness. The machine was built using the same measurement system and the same roll-shoe centerless fixture as the grinding machines used for the production of the parts. The machine was designed and set up such that disturbances of the measurement are minimized. It was shown that the machine reaches accuracies close to those obtained by manually operated roundness machines. The cycle time is approximately 4 seconds per part compared to several minutes for manually operated roundness machines. As a second objective, the possibility of measuring waviness directly in the grinding machine was evaluated. Feasible design modifications to reduce the effect of disturbances are very limited in grinding machines, since interference with the grinding process must be avoided. Therefore, analytical methods were developed to reduce these effects and partly restore the original profile. The main disturbances that were addressed are errors due to irregular sampling of the profile, to the frequency response behavior of the gage heads, and to motion of the workpiece center relative to the gage heads. The post-process machine was used as a development and test platform for the analytical methods. To further verify these methods, tests were also conducted in an industrial grinding machine.
92

Automatic Tongue Feature Extraction

Hsu, Yu-Cheng 06 July 2010 (has links)
In recent years, Chinese medicine in the medical profession in the West triggered a wave of new wave. Chinese medicine is based on four examinations which are listening and smelling examination, inquiry, and palpation to diagnose the patient. Tongue diagnosis is also the first of four diagnostic. The result of tongue diagnosis is based on features of tongue which are diagnosed by doctor. Observation of the tongue focuses on the tongue phenomenon which is structured by the shape of the tongue, and the substance of the tongue, and the coating of the tongue. Pathology of the tongue-shaped includes the medium, fat, lean and crooked, etc. In Pathology of the tongue-substanced, tongue color includes pale, closed to pale, reddish, red, dark red, dark purple, also have some features about ecchymosis, breaken line, tooth mark, and red dot. Pathology for the coating of the tongue includes white, yellow, black, greasy, thick, thin, peeling, or no, etc. Clinically, doctors mostly rely on their own knowledge and experience when determining major lesions of a patient by observing the coloration, overall modalities, and volume of salivary on different parts of the tongue. As a result, the diagnosis tends to be limited by knowledge, experience, train of thought, and diagnostic techniques.The subjective determination is likely to be affected by the doctor¡¦s color sensitivity and interpretation.Different doctors may come to drastically different judgments on the same tongue presentation with little overlap. Therefore, it is important to develop scientific methods that can help doctors diagnose based on standardized differentiation procedures and render reliable diagnoses in order to enhance the clinical application value of Chinese Medicine.The computerized automatic capture of characteristics shown on the images of the surface.At first, the captured image achieves brightness and color correction by brightness calibration and color calibration. Then, the original tongue images go through HSI color space conversion, detection of the control points inside and outside the surface of the tongue, curve smoothness modification and active contour model to capture images of the tongue. After that, the tongue shape, tongue fur, tongue body, and body fluid are captured from the image of the tongue.
93

A Study on Certification Mechanism Design for Deep Sea Water Applications

Luo, Wen-yan 03 August 2006 (has links)
Characterized as rich mineral substances, low temperature, few bacteria, and stability with numerous implementation aspects on aquaculture, food, drinking, and leisure, the development of deep sea water (DSW) has become a governmental policy and a new industry. The eastern region in Taiwan owns outstanding pumping DSW conditions and a prosperity on its industry applications is expected if the development project goes well. However, a design on the inspection mechanism is critical to the industry development due to water's indifference characteristics. This study aims at inspection problems relevant with certification mechanism to construct an overall certification operation system. An investigation is designed to understand the current inspection system status while implementation for the use of lab function requirements, inspection operation, and product inspection process considerations. A management conceptual mechanism is also provided for DSW industry development in the future
94

Automatic Tongue Diagnosis System

Hsu, Cheng-chun 28 July 2009 (has links)
The core of diagnosis in Chinese Medicine is ¡§pattern identification/syndrome differentiation and treatment¡¨ with inspection, listening and smelling examination, inquiry, and palpation as the bases. Tongue diagnosis tops the four diagnoses and hence is crucial to the inspection diagnosis in Chinese Medicine. Clinically, doctors mostly rely on their own knowledge and experience when determining major lesions of a patient by observing the coloration, overall modalities, and volume of salivary on different parts of the tongue. As a result, the diagnosis tends to be limited by knowledge, experience, train of thought, and diagnostic techniques.The subjective determination is likely to be affected by the doctor¡¦s color sensitivity and interpretation.Different doctors may come to drastically different judgments on the same tongue presentation with little overlap. Therefore, it is important to develop scientific methods that can help doctors diagnose based on standardized differentiation procedures and render reliable diagnoses in order to enhance the clinical application value of Chinese Medicine.The computerized automatic capture of characteristics shown on the images of the surface and the back of the tongue comprises breakup of the tongue image and capture of the tongue characteristics.The original tongue images first go through HSI color space conversion, detection of the control points inside and outside the surface of the tongue, curve smoothness modification and active contour model to capture images of the tongue. After that, the tongue shape, tongue fur, tongue body, and body fluid are captured from the breakup image of the tongue.
95

Examination of natural background sources of radioactive noble gases with CTBT significance

Johnson, Christine Michelle 24 March 2014 (has links)
For verifying the Comprehensive Nuclear-Test-Ban Treaty (CTBT), different monitoring technologies (seismic, infrasound, hydroacoustic, and radionuclide detection) are combined. The monitoring of radioactive xenon isotopes is one of the principal methods for the determination of the nuclear nature of an explosion. After an underground nuclear detonation the radioxenon isotopes [superscript 131m]Xe, [superscript 133m]Xe, ¹³³Xe, and ¹³⁵Xe, and the radioargon isotope ³⁷Ar have an increased probability of detection. In order to effectively utilize these isotopes as indicators of nuclear testing, an accurate background must be calculated. This work examines the fission products produced by spontaneous fission of ²³⁸U, which is naturally present in the earth's crust, and of ²⁴⁰Pu which is present as a product of nuclear weapons and nuclear reactor accidents. These calculations provide a range of production values for radioxenon in a variety of geologies as well as at various historic locations. The activation of geologic calcium and potassium by cosmic ray neutrons is considered for a variety of properties effecting the neutron flux. These calculations provide a range of radioargon production values across a selection of geologies. The impact of latitude and the solar activity cycle are also examined. In order to examine the transport of the isotopes through soil a model of the transport of xenon and argon through various geologies was developed. This model incorporates both the introduction of xenon from the atmosphere and that produced by spontaneous fission. This is then considered in light of what might be observed in an on-site inspection (OSI). What this work finds is that the radioxenon natural background does exceed detection limits in particular locations and geologies, however, a careful examination of the location and the ideal sampling depths can minimize the impact during an OSI. Radioargon, however, has a much larger natural background at shallow depths which are the realm of OSI sampling. Should radioargon sampling be used in an OSI the sampling time is crucial in distinguishing a nuclear explosion from the natural background. In some scenarios the natural background production of radioargon may be sufficient to interfere with the detection of an underground nuclear weapon test. This information may be beneficial in the development of future OSI noble gas monitoring techniques. / text
96

Understanding the policy process of mandatory building inspection in Hong Kong

Chan, Chun-man., 陳俊文. January 2011 (has links)
published_or_final_version / Politics and Public Administration / Master / Master of Public Administration
97

Optimum inspection and maintenance intervals for processes subject to chance and wearout failures

Buckley, James Joseph 08 1900 (has links)
No description available.
98

Machine Vision Based Inspection: Case Studies on 2D Illumination Techniques and 3D Depth Sensors

YAN, MICHAEL T 01 March 2012 (has links)
This paper investigates two distinct, but related, topics in machine vision. The first is the effect of lighting on the performance of a 2D vision-based inspection system. The lighting component of machine vision has often been overlooked; an attempt was made to quantify the impact on existing machine vision algorithms. The second topic explores the applications of a data-rich 3D vision sensor that is capable of providing depth data in a wide range of ambient lightning conditions for industrial applications. A focus is placed on inspection systems with the depth data provided by the sensor. Three basic lighting geometries were compared quantitatively based on discriminant analysis in an inspection task that checked for the presence of J-clips on an aluminum carrier. Two different LabVIEW® machine vision algorithms were used to evaluate backlight, bright field and dark field illumination on their ability to minimize the span of the pass (clip present) and fail (clip absent) sample sets, as well as maximize the separation between these sample sets. Results showed that there were clear differences in performance with the different lighting geometries, with over a 30% change in performance. Although it has long been accepted that the choice of lighting for machine vision systems is not a trivial exercise, this paper provides a quantitative measure of the impact lighting has on the performance of feature-based machine vision. The Microsoft Kinect® is a commercial vision sensor that can simultaneously provide a colour video stream, comparable to current webcam technologies, in addition to a depth stream that provides three-dimensional information of the camera’s field of view and is invariant to environmental lighting. An experiment was carried out to characterize the sensor’s accuracy and precision, and to evaluate its performance as an inspection system to determine the orientation of a wheel. Tests were also conducted to determine the effect that changes in the physical environment had on performance. These changes included camera height, lighting and surface material. Results of the experiment have shown that the sensor has an average precision of ±0.12 cm and average accuracy of 0.5 cm, both with less than a 30% change when varying physical features. A discriminant analysis was performed to measure inspection performance, which showed less than 30% change with set separation, but not for set span. No trends were apparent with the change in set span relating to the change in physical features. / Thesis (Master, Mechanical and Materials Engineering) -- Queen's University, 2012-02-29 18:33:20.505
99

Smart structural health monitoring of mining support units.

Apsey, Jason. January 2003 (has links)
In the South African mining industry, the design of tunnel support systems is generally based on empirical methodologies that consider rockmass characteristics as well as the type of loading (e.g. seismic) that the excavation experiences. The design methodologies are by no means infallible, and work is continually being conducted to improve the classification of excavation conditions and thereby improve the selection of a suitable support system. This study is concerned with finding a means to monitor the installed support units rather than with improving the classification methodologies. It is postulated that with the extraction of accurate information describing the state of any support unit at any given time, areas of instability in the tunnel can be readily identified and strengthened~ Also, the information gathered as to the behaviour of the support units in a particular region can be used to assist in understanding the environmental characteristics of that region (rockmass, loading, etc.). A material survey was conducted to identify suitable candidates that could feasibly be used in either a passive (feedback when interrogated) or active (constant feedback) structural health monitoring system. The preferred candidates identified in this study are the group of passive smart materials referred to as TRIP steels, which are a subset of strain memory alloys. TRIP steels exhibit microstructural changes from paramagnetic austenite to ferromagnetic martensite as a function of increasing deformation at a given temperature.. The strength of the magnetic field at critical locations provides an indication as to the health state of the component. Because of their high strengths and ductility, TRIP steels can be used as what amounts to a self-monitoring support unit (interrogation apparatus required). Finite element methods are a practical means of predicting the mechanical and magnetostatic behaviour of TRIP steel structural members once material equations have been established by experiment. / Thesis (Ph.D.)-University of Natal, Durban, 2003.
100

Damage detection and health monitoring of structures using dynamic response and neural network techniques

Luo, Huageng 08 1900 (has links)
No description available.

Page generated in 0.1081 seconds