301 research outputs found

    Development of Machine Vision Based Workstation for Laser Micromachining

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    Today, laser based micromachining technologies enable the most advanced material manufacturing. Since it has wide range of applications in Microelectronics, medical device, aerospace etc., the accuracy of the process is of utmost significance. The current project proposes a machine vision assisted workstation for laser micromachining. The machine vision system not only has the ability to control the Laser path but also has the ability to locate the starting point of machining. The system was designed and developed from basic components, while MATLAB was used to control the laser direction, and to image the specimen. To analyse the limitations of the developed system, a rectangular shape was machined. Subsequently, known magnitudes of translational and rotational movements were given to the specimen. The images of machined area were captured before and after transformation. MATLAB algorithm was used to process the images to find the initial point of machined area on the transformed specimen. The laser beam is then guided to that point and the machining is repeated. The specimen was measured under microscope to find the error between the former and latter machined paths. Translational and angular errors were measured for various transformations. In this study, the challenges and corresponding possible solutions that are encountered in machining complex geometries are addressed. The study proposes mathematical function based and image processing based algorithms to find the machining coordinates and function-based approach was found to be more efficient for complex geometries. Furthermore, the effect of process parameters on the overall quality of the manufacturing are discussed. The COMSOL software was used to model all the effect of laser parameters on the roughness, depth and thickness of machined path. To validate the numerical model, experiments were conducted for different process parameters the results are in good agreement with a simulation results. The simulated model can be used to estimate the effect of the process parameters before the machining. Since the laser beam can be controlled on the geometry of the specimen and the study demonstrates the minimum possible error, this system can be applied to manufacture and repair wide range of microstructures

    NASA patent abstracts bibliography: A continuing bibliography. Section 1: Abstracts (supplement 23)

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    Abstracts are cited for 129 patents and patent applications introduced into the NASA scientific and technical information system during the period January 1983 through June 1983. Each entry consists of a citation, an abstract, and in most cases, a key illustration selected from the patent or patent application

    Optical MEMS

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    National Postirradiation Examination Workshop Report

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    Technology 2003: The Fourth National Technology Transfer Conference and Exposition, volume 2

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    Proceedings from symposia of the Technology 2003 Conference and Exposition, Dec. 7-9, 1993, Anaheim, CA, are presented. Volume 2 features papers on artificial intelligence, CAD&E, computer hardware, computer software, information management, photonics, robotics, test and measurement, video and imaging, and virtual reality/simulation

    Advanced Automation for Space Missions

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    The feasibility of using machine intelligence, including automation and robotics, in future space missions was studied

    Space Station Workshop: Commercial Missions and User Requirements

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    The topics of discussion addressed during a three day workshop on commercial application in space are presented. Approximately half of the program was directed towards an overview and orientation to the Space Station Project; the technical attributes of space; and present and future potential commercial opportunities. The remaining time was spent addressing technological issues presented by previously-formed industry working groups, who attempted to identify the technology needs, problems or issues faced and/or anticipated by the following industries: extraction (mining, agriculture, petroleum, fishing, etc.); fabrication (manufacturing, automotive, aircraft, chemical, pharmaceutical and electronics); and services (communications, transportation and retail robotics). After the industry groups presented their technology issues, the workshop divided into smaller discussion groups composed of: space experts from NASA; academia; industry experts in the appropriate disciplines; and other workshop participants. The needs identified by the industry working groups, space station technical requirements, proposed commercial ventures and other issues related to space commercialization were discussed. The material summarized and reported are the consensus from the discussion groups

    Enabling and Understanding Failure of Engineering Structures Using the Technique of Cohesive Elements

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    In this paper, we describe a cohesive zone model for the prediction of failure of engineering solids and/or structures. A damage evolution law is incorporated into a three-dimensional, exponential cohesive law to account for material degradation under the influence of cyclic loading. This cohesive zone model is implemented in the finite element software ABAQUS through a user defined subroutine. The irreversibility of the cohesive zone model is first verified and subsequently applied for studying cyclic crack growth in specimens experiencing different modes of fracture and/or failure. The crack growth behavior to include both crack initiation and crack propagation becomes a natural outcome of the numerical simulation. Numerical examples suggest that the irreversible cohesive zone model can serve as an efficient tool to predict fatigue crack growth. Key issues such as crack path deviation, convergence and mesh dependency are also discussed

    NASA SBIR abstracts of 1990 phase 1 projects

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    The research objectives of the 280 projects placed under contract in the National Aeronautics and Space Administration (NASA) 1990 Small Business Innovation Research (SBIR) Phase 1 program are described. The basic document consists of edited, non-proprietary abstracts of the winning proposals submitted by small businesses in response to NASA's 1990 SBIR Phase 1 Program Solicitation. The abstracts are presented under the 15 technical topics within which Phase 1 proposals were solicited. Each project was assigned a sequential identifying number from 001 to 280, in order of its appearance in the body of the report. The document also includes Appendixes to provide additional information about the SBIR program and permit cross-reference in the 1990 Phase 1 projects by company name, location by state, principal investigator, NASA field center responsible for management of each project, and NASA contract number

    COBE's search for structure in the Big Bang

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    The launch of Cosmic Background Explorer (COBE) and the definition of Earth Observing System (EOS) are two of the major events at NASA-Goddard. The three experiments contained in COBE (Differential Microwave Radiometer (DMR), Far Infrared Absolute Spectrophotometer (FIRAS), and Diffuse Infrared Background Experiment (DIRBE)) are very important in measuring the big bang. DMR measures the isotropy of the cosmic background (direction of the radiation). FIRAS looks at the spectrum over the whole sky, searching for deviations, and DIRBE operates in the infrared part of the spectrum gathering evidence of the earliest galaxy formation. By special techniques, the radiation coming from the solar system will be distinguished from that of extragalactic origin. Unique graphics will be used to represent the temperature of the emitting material. A cosmic event will be modeled of such importance that it will affect cosmological theory for generations to come. EOS will monitor changes in the Earth's geophysics during a whole solar color cycle
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