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Articles 1 - 13 of 13

Full-Text Articles in Mechanical Engineering

Approximating A Three-Dimensional Fluidized Bed With Two-Dimensional Simulations, Mirka Deza, Francine Battaglia, Theodore J. Heindel Oct 2008

Approximating A Three-Dimensional Fluidized Bed With Two-Dimensional Simulations, Mirka Deza, Francine Battaglia, Theodore J. Heindel

Mechanical Engineering Conference Presentations, Papers, and Proceedings

Fluidized beds can be used to gasify biomass in the production of producer gas, a flammable gas that can replace natural gas in process heating. Modeling these reactors with computational fluid dynamics (CFD) simulations is advantageous when performing parametric studies for design and scale-up. From a computational resource point of view, two-dimensional simulations are easier to perform than three-dimensional simulations, but they may not capture the proper physics. This paper will compare two- and three-dimensional simulations in a 10.2 cm diameter fluidized bed with side air injection to determine when two-dimensional simulations are adequate to capture the bed hydrodynamics ...


Simulating Gas-Liquid Flows In An External Loop Airlift Reactor, Deify Law, Francine Battaglia, Theodore J. Heindel Oct 2008

Simulating Gas-Liquid Flows In An External Loop Airlift Reactor, Deify Law, Francine Battaglia, Theodore J. Heindel

Mechanical Engineering Conference Presentations, Papers, and Proceedings

The external loop airlift reactor (ELALR) is a modified bubble column reactor that is composed of two vertical columns that are connected with two horizontal connectors. Airlift reactors are utilized in fermentation processes and are preferred over traditional bubble column reactors because they can operate over a wider range of conditions. Computational fluid dynamics (CFD) simulations can be used to enhance our understanding of the hydrodynamics within these reactors. In the present work, the gas-liquid flow dynamics in an external loop airlift reactor are simulated using CFDLib with an Eulerian-Eulerian ensemble-averaging method in two-dimensional (2D) and three-dimensional (3D) coordinate systems ...


Proper Orthogonal Decomposition-Based Reduced Order Model Of A Hydraulic Mixing Nozzle, Sunil Suram, Douglas S. Mccorkle, Kenneth M. Bryden Sep 2008

Proper Orthogonal Decomposition-Based Reduced Order Model Of A Hydraulic Mixing Nozzle, Sunil Suram, Douglas S. Mccorkle, Kenneth M. Bryden

Mechanical Engineering Conference Presentations, Papers, and Proceedings

In this work, a reduced order model is constructed for a hydraulic mixing nozzle using proper orthogonal decomposition. Data from several CFD computations are collected to provide the data for input to the reduced order model and flow is projected onto the most dominant principal axes to study the flow structures. Flow structures are compared for the original and optimized shape nozzles to study the effect of changing the nozzle’s shape on the flow characteristics. This study also addresses issues regarding the time required for collecting CFD data and how it has been reduced by using a modified convergence ...


Minimum Fluidization Velocity And Gas Holdup In Fluidized Beds With Side Port Air Injection, Nathan P. Franka, Joshua B. Drake, Theodore J. Heindel Aug 2008

Minimum Fluidization Velocity And Gas Holdup In Fluidized Beds With Side Port Air Injection, Nathan P. Franka, Joshua B. Drake, Theodore J. Heindel

Mechanical Engineering Conference Presentations, Papers, and Proceedings

Fluidized beds can be used to gasify biomass in the production of producer gas, a flammable gas that can replace natural gas in process heating. Knowing how the fluidized bed hydrodynamics vary as reactor dimensions are scaled up is vital for improving reactor efficiency. This study utilizes 10.2 cm and 15.2 cm diameter fluidized beds with added side port air injection to investigate column diameter effects on fluidized bed hydrodynamics. Both inert (glass beads) and biomass (ground walnut shell and ground corncob) bed materials are used and the hydrodynamic differences with side port air injection are recorded. Minimum ...


Interactive Deformation Through Mesh-Free Stress Analysis In Virtual Reality, Daniela Faas, Judy M. Vance Aug 2008

Interactive Deformation Through Mesh-Free Stress Analysis In Virtual Reality, Daniela Faas, Judy M. Vance

Mechanical Engineering Conference Presentations, Papers, and Proceedings

Virtual reality (VR) techniques are used to create an environment that allows an engineer to modify the shape of a part and see the changes in the stress state immediately. A virtual reality application, Interactive Virtual Design Application (IVDA), that allows fast mesh-free analysis of multiple element types, including two-dimensional (2D) elements, is described in detail. Taylor series approximations and Pre-conditioned Conjugate Gradient (PCG) methods are used with mesh-free analysis to perform quick reanalysis during interactive shape modification. Prior to this work, only 3D elements were incorporated into the method. The addition of 2D elements greatly expands the potential application ...


A General Architecture For Distributed Vr Interfaces, Thomas Batkiewicz, Abhishek Seth, Bryan Walter, Jared Knutzon, James H. Oliver Aug 2008

A General Architecture For Distributed Vr Interfaces, Thomas Batkiewicz, Abhishek Seth, Bryan Walter, Jared Knutzon, James H. Oliver

Mechanical Engineering Conference Presentations, Papers, and Proceedings

This paper describes a software architecture useful in creating new virtual reality interfaces across a clustered network of computers. The architecture takes advantage of a concept common to desktop application development, the event loop, and provides a method by which it can be shared effectively between nodes in a cluster. This method improves upon the common replication approach to cluster synchronization by creating a single, simple object to share, as well as by supporting node specialization in a generic cluster. The method is designed to be easily added to existing applications as well as speed the development of virtual reality ...


A Validation Study For The Hydrodynamics Of Biomass In A Fluidized Bed, Mirka Deza, Francine Battaglia, Theodore J. Heindel Aug 2008

A Validation Study For The Hydrodynamics Of Biomass In A Fluidized Bed, Mirka Deza, Francine Battaglia, Theodore J. Heindel

Mechanical Engineering Conference Presentations, Papers, and Proceedings

Computational modeling of fluidized beds can be used to predict operation of biomass gasifiers after extensive validation with experimental data. The present work focused on computational simulations of a fluidized bed using a multifluid Eulerian-Eulerian model to represent the gas and solid phases as interpenetrating continua. Hydrodynamic results from the simulations were quantitatively compared with X-ray flow visualization studies of a similar bed. It was found that the Gidaspow model can accurately predict the hydrodynamics of the biomass in a fluidized bed. The coefficient of restitution of biomass was fairly high and did not affect the hydrodynamics of the bed ...


High Dynamic Range Scanning Technique, Song Zhang, Shing-Tung Yau Aug 2008

High Dynamic Range Scanning Technique, Song Zhang, Shing-Tung Yau

Mechanical Engineering Conference Presentations, Papers, and Proceedings

Measuring objects with high surface reflectivity variations (i.e., high dynamic range) is challenging for any optical method. This paper addresses a high dynamic range scanning (HDRS) technique that can measure this type of objects. It takes advantage of one merit of a phase-shifting algorithm: pixel-by-pixel phase retrieval. For each measurement, multiple shots of fringe images with different exposures are taken. And a sequence of fringe images with different overall brightness are captured: the brightest fringe images have good fringe quality for darker areas although the brighter areas may be saturated; while the darkest fringe images have good fringe quality ...


Virtual Reality Based Multi-Modal Teleoperation Using Mixed Autonomy, Muthukkumar S. Kadavasal, Abhishek Seth, James H. Oliver Aug 2008

Virtual Reality Based Multi-Modal Teleoperation Using Mixed Autonomy, Muthukkumar S. Kadavasal, Abhishek Seth, James H. Oliver

Mechanical Engineering Conference Presentations, Papers, and Proceedings

A multi modal teleoperation interface is introduced featuring an integrated virtual reality based simulation augmented by sensors and image processing capabilities on-board the remotely operated vehicle. The proposed virtual reality interface fuses an existing VR model with live video feed and prediction states, thereby creating a multi modal control interface. Virtual reality addresses the typical limitations of video-based teleoperation caused by signal lag and limited field of view thereby allowing the operator to navigate in a continuous fashion. The vehicle incorporates an on-board computer and a stereo vision system to facilitate obstacle detection. A vehicle adaptation system with a priori ...


Simultaneous Geometry And Color Texture Acquisition Using A Single-Chip Color Camera, Song Zhang, Shing-Tung Yau Aug 2008

Simultaneous Geometry And Color Texture Acquisition Using A Single-Chip Color Camera, Song Zhang, Shing-Tung Yau

Mechanical Engineering Conference Presentations, Papers, and Proceedings

Capturing 3-D geometry and the perfectly aligned color texture simultaneously is crucial for diverse fields including entertainment, target recognition, and computer graphics. However, it is very challenging for a conventional technique because of a number of problems related to color. Previous researchers rely heavily on using two cameras: a black-and-white(B/W) camera to measure the geometry, and a color camera to capture the color texture. However, aligning the color image with the 3-D geometry point by point remains difficult. In this research, we propose a novel technique that uses a single-chip color camera to capture both geometry and color ...


Inverse Dynamic Equilibrium Analysis Of Mechanical Systems Undergoing Prescribed Rotational Motions, Dong Hwan Choi, Jonathan A. Wickert Jul 2008

Inverse Dynamic Equilibrium Analysis Of Mechanical Systems Undergoing Prescribed Rotational Motions, Dong Hwan Choi, Jonathan A. Wickert

Mechanical Engineering Conference Presentations, Papers, and Proceedings

Mechanical systems that undergo prescribed rotational motions arise in such engineered systems as robots, spacecraft, propulsion and power generation systems, and certain sensors and actuators. In order to avoid the resonance or the critical speed of the system and to keep the desired dynamic equilibrium state in the mechanical system undergoing rotational motions, the system’s design parameter values or driving angular speed should be tuned. In this work, a general formulation for the inverse dynamic equilibrium analysis is developed to directly calculate the driving angular speed or design parameter values which satisfy the condition of the desired dynamic equilibrium ...


Implementation Of Digital Pheromones In Pso Accelerated By Commodity Graphics Hardware, Vijay Kalivarapu, Eliot H. Winer Jan 2008

Implementation Of Digital Pheromones In Pso Accelerated By Commodity Graphics Hardware, Vijay Kalivarapu, Eliot H. Winer

Mechanical Engineering Conference Presentations, Papers, and Proceedings

In this paper, a model for Graphics Processing Unit (GPU) implementation of Particle Swarm Optimization (PSO) using digital pheromones to coordinate swarms within ndimensional design spaces is presented. Previous work by the authors demonstrated the capability of digital pheromones within PSO for searching n-dimensional design spaces with improved accuracy, efficiency and reliability in both serial and parallel computing environments using traditional CPUs. Modern GPUs have proven to outperform the number of floating point operations when compared to CPUs through inherent data parallel architecture and higher bandwidth capabilities. The advent of programmable graphics hardware in the recent times further provided a ...


Implementation Of Digital Pheromones In Particle Swarm Optimization For Constrained Optimization Problems, Vijay Kalivarapu, Eliot H. Winer Jan 2008

Implementation Of Digital Pheromones In Particle Swarm Optimization For Constrained Optimization Problems, Vijay Kalivarapu, Eliot H. Winer

Mechanical Engineering Conference Presentations, Papers, and Proceedings

This paper presents a model for digital pheromone implementation of Particle Swarm Optimization (PSO) to solve constrained optimization problems. Digital pheromones are models simulating real pheromones produced by insects for communication to indicate a source of food or a nesting location. When integrated within PSO, this principle of communication and organization between swarm members offer substantial improvement in search accuracy, efficiency and reliability. Multiple pheromones are released in the design space, and the strength of a pheromone in a region of the design space is determined through empirical proximity analysis, and. The swarm then reacts accordingly based on the probability ...