Development of a novel 3D simulation modelling system for distributed manufacturing

This paper describes a novel 3D simulation modelling system for supporting our distributed machine design and control paradigm with respect to simulating and emulating machine behaviour on the Internet. The system has been designed and implemented using Java2D and Java3D. An easy assembly concept of drag-and-drop assembly has been realised and implemented by the introduction of new connection features (unified interface assembly features) between two assembly components (modules). The system comprises a hierarchical geometric modeller, a behavioural editor, and two assemblers. During modelling, designers can combine basic modelling primitives with general extrusions and integrate CAD geometric models into simulation models. Each simulation component (module) model can be visualised and animated in VRML browsers. It is reusable. This makes machine design re-configurable and flexible. A case study example is given to support our conclusions

Holographic enhanced remote sensing system

The Holographic Enhanced Remote Sensing System (HERSS) consists of three primary subsystems: (1) an Image Acquisition System (IAS); (2) a Digital Image Processing System (DIPS); and (3) a Holographic Generation System (HGS) which multiply exposes a thermoplastic recording medium with sequential 2-D depth slices that are displayed on a Spatial Light Modulator (SLM). Full-parallax holograms were successfully generated by superimposing SLM images onto the thermoplastic and photopolymer. An improved HGS configuration utilizes the phase conjugate recording configuration, the 3-SLM-stacking technique, and the photopolymer. The holographic volume size is currently limited to the physical size of the SLM. A larger-format SLM is necessary to meet the desired 6 inch holographic volume. A photopolymer with an increased photospeed is required to ultimately meet a display update rate of less than 30 seconds. It is projected that the latter two technology developments will occur in the near future. While the IAS and DIPS subsystems were unable to meet NASA goals, an alternative technology is now available to perform the IAS/DIPS functions. Specifically, a laser range scanner can be utilized to build the HGS numerical database of the objects at the remote work site

PLOT3D user's manual

PLOT3D is a computer graphics program designed to visualize the grids and solutions of computational fluid dynamics. Seventy-four functions are available. Versions are available for many systems. PLOT3D can handle multiple grids with a million or more grid points, and can produce varieties of model renderings, such as wireframe or flat shaded. Output from PLOT3D can be used in animation programs. The first part of this manual is a tutorial that takes the reader, keystroke by keystroke, through a PLOT3D session. The second part of the manual contains reference chapters, including the helpfile, data file formats, advice on changing PLOT3D, and sample command files

Modeling And Development Of A MEMS Device For Pyroelectric Energy Scavenging

As the world faces an energy crisis with depleting fossil fuel reserves, alternate energy sources are being researched ever more seriously. In addition to renewable energy sources, energy recycling and energy scavenging technologies are also gaining importance. Technologies are being developed to scavenge energy from ambient sources such as vibration, radio frequency and low grade waste heat, etc. Waste heat is the most common form of wasted energy and is the greatest potential source of energy scavenging. Pyroelectricity is the property of some materials to change the surface charge distribution with the change in temperature. These materials produce current as temperature varies in them and can be utilized to convert thermal energy to electrical energy. In this work a novel approach to vary temperature in pyroelectric material to convert energy has been investigated. Microelectromechanical Systems or MEMS is the new technology trend that takes advantage of unique physical properties at micro scale to create mechanical systems with electrical interface using available microelectronic fabrication techniques. MEMS can accomplish functionalities that are otherwise impossible or inefficient with macroscale technologies. The energy harvesting device modeled and developed for this work takes full benefit of MEMS technology to cycle temperature in an embedded pyroelectric material to convert thermal energy from low grade waste heat to electrical energy. Use of MEMS enables improved performance and efficiency and overcomes problems plaguing previous attempts at pyroelectric energy conversion. A Numerical model provides accurate prediction of MEMS performance and sets design criteria, while physics based analytical model simplifies design steps. A SPICE model of the MEMS device incorporates electrical conversion and enables electrical interfacing for current extraction and energy storage. Experimental results provide practical implementation steps towards of the modeled device. Under ideal condition the proposed device promises to generate energy density of 400 W/L

Analytical and numerical studies on macro and micro scale heat sinks for electronics applications

Thesis (M.S.) University of Alaska Fairbanks, 2003From the practice in computer industry the standard approach for electronics cooling is fan-cooled heat sinks. We developed thermal models for forced convection heat sinks. An Intel Pentium ill chip has been adopted as a preliminary design case to develop necessary equations. We found the heat dissipated from the aluminum heat sink, based upon different modes of airflow over the fins. We also considered radiation heat transfer. We performed transient heat transfer analysis to determine the time to attain the steady state temperature for the whole system for macro and micro scale also. Next, we refined our one-dimensional analytical convection analysis using the numerical analysis. This was done using the computational fluid dynamics code Fluent to obtain accurate velocity fields over the fins. Using these improved velocities, convective heat transfer coefficients were computed. Next, we have miniaturized the processor chip size to the micrometer scale and have designed a heat sink based upon the models we have developed. Calculations of mean free path and Knudsen number shows the continuum theory for air still holds for our designed micro-channels. Equations for natural convection heat sinks are also explored as a part of this study. In the microscale study, we did forced and natural convection analysis.1. Introduction -- 2. Theory -- 3. Analytical solutions for macro scale chip -- 4. Application to microscale chips -- 5. Conclusions -- References

An interface between the GRASS geographic information system and ORACLE relational detabase management system

A query and display interface has been developed between the GRASS geographic information system and the SQL-based ORACLE relational database management system (DBMS) . This interface enables multiple non-spatial attributes of GRASS map features to be maintained with the DBMS. GRASS alone is capable of storing only one attribute per feature. The interface allows the user to provide both spatial (GRASS) and non-spatial (SQL) selection criteria for any query. Spatial selection methods include picking items from the GRASS map with a mouse, and specifying areas of interest with user-drawn (via a mouse) polygons and transects. The results of the combined query are displayed both graphically (the selected GRASS map features are highlighted in a graphics window) and textually (the DBMS attribute data are shown in a text display window). Options include creating reclassified maps based on the DBMS output, and updating the attributes retrieved by a query

Circuit tutor : a computer-aided learning package for electrical engineering

The development of Circuit Tutor, the subject of this dissertation, resulted from a conviction that computers can further enrich the Electronic Engineering curriculum. After an investigation into the different roles of the computer in education the use of modelling and simulation was selected as an effective Computer Aided Learning method. It was realised that the development of any non-trivial simulation program is however not an easy task. The programmer must not only model the circuit behaviour, but also write the man-machine interface (MMI). The main goal of Circuit Tutor was to provide a ready-made simulation environment which makes effective use of the graphics capabilities of the microcomputer for the simulation of a whole class of electrical circuit simulations. To facilitate rapid prototyping the installer is provided with: (1) a man-machine interface which provides the user with a graph, 3 meters, a circuit diagram of the circuit, a menu facility, windows to view circuit parameters and outputs: (2) a program scheduler; (3) a library of maths functions, including Gauss-Jordan elimination of complex matrices; and (4) Circuit Draw: a utility to draw a circuit diagram. Particular emphasis was placed on the design of the user's interface. It has been possible to restrict the effort to link in a new circuit model to 3 modifications to the man-machine interface (MMI) part of the program. Present software and MMI design were investigated. Circuit Tutor and Circuit Draw were developed using modular software design techniques. A modular design chart similar to that proposed by Wiener (1984) was found to be useful during the design stages of both Circuit Tutor and Circuit Draw. Available computer languages for the IBM PC were evaluated and Turbo Pascal selected, as it offered most of the features necessary for the implementation of a modern, modular software design. Four circuits were implemented to serve as examples. The documentation was structured in a manner appropriate to a software project: Part 1 gives an introduction to computers in education and provides the rationale for the use of simulation. A brief overview of Circuit Tutor and Circuit Draw is presented. Part 2 contains the User's Reference Manual for Circuit Tutor and the Circuit Draw Utility. Part 3 contains the Designer's Reference Manual for Circuit Tutor and the Circuit Draw Utility

Automated software development workstation

Engineering software development was automated using an expert system (rule-based) approach. The use of this technology offers benefits not available from current software development and maintenance methodologies. A workstation was built with a library or program data base with methods for browsing the designs stored; a system for graphical specification of designs including a capability for hierarchical refinement and definition in a graphical design system; and an automated code generation capability in FORTRAN. The workstation was then used in a demonstration with examples from an attitude control subsystem design for the space station. Documentation and recommendations are presented

DESIGN AND SIMULATION OF A NERVE TRACER SYSTEM FOR VAGOTOMY SURGERY

The vagus nerve is one of the most important nerves in the human body. It is associated with a plethora of functions one of them being acid secretion inside the stomach to aid in digestion. The cerebrum part of the brain initiates an action potential that is propagated along the vagus nerve to the parietal cells that secrete acid. In some cases, the cerebrum over stimulates the parietal cells leading to excess acid secretion, more than is needed for the digestion process. This excess acid leads to the formation of open sores along the stomach lining called gastric/peptic ulcers. In some cases, these gastric ulcers are curable by taking medicines. In other cases, medicines have little or no effect on these gastric ulcers and a surgical intervention, called a vagotomy is recommended to cure the gastric ulcers. Vagotomy is the surgical cutting of the vagus nerve branches that link the brain to the parietal cells that produce acid. Once a branch is cut, the signal from the cerebrum is blocked and acid production is reduced thereby reducing the formation of ulcers. Vagotomy surgery can be challenging to perform. The major hurdle facing surgeons is locating the vagus nerve branch responsible for excess acid secretion in a specific zone of the stomach. If the surgeons are unable to locate the correct branch or cut other nerve branches, it will not cure the gastric ulcer problem and the entire surgical exercise may need to be revised. Thus there is a need to develop a system that would help surgeons locate and identify the correct vagus nerve branch to cut during the vagotomy surgery. A system that artificially excites the vagus nerve and provides the surgeon feedback that the laparoscopic tool is near the vagus nerve branch of interest is proposed and designed. To facilitate the design process, an external electrical stimulation model of a human vagus nerve was developed using COMSOL Multiphysics simulation software. The nerve model is built in the simulation software using the approximate geometric and material properties of the human vagus nerve. The model recapitulates the salient feature that if an applied electric potential exceeds a threshold potential, it leads to the generation of an action potential that propagates through the length of the vagus nerve. The proposed vagus nerve tracer consists of a stimulation cuff to inject a trace signal into the vagus nerve and a receiver probe that can be placed near a nerve to detect the presence of the trace signal. The stimulation cuff is a set of copper electrodes that would be placed around the vagus nerve at a point above the stomach where the vagus nerve is clearly visible and accessible to the surgeons. The detector probe is designed as copper hook monopolar tip that could be affixed to a laparoscopic instrument. It can be placed around the vagus nerve branch without damaging it and can detect the action potential. An important third component is the square wave used as the trace signal. The developed system thus comprises the vagus nerve artificial electrical stimulation cuff, trace signal, and detector probe. Computer simulations have been performed to optimize the proposed design and to demonstrate its functionality and potential value to help surgeons overcome the complication of locating the correct branch of vagus nerve to cut during the vagotomy surgery