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RESEARCH SUMMARIES

Last revised Mar, 2006.

Research in the Department covers projects in the general areas of Systems and Design, Mechanics and Materials, and the Fluid and Thermal Sciences. Specific topics include acoustics and noise control, bioengineering, combustion, computer-aided design and optimization, dynamic systems and control, energy and thermal systems engineering, environmental engineering, fluid mechanics, heat and mass transfer, metallurgy and material science, solid mechanics and structures, vehicle dynamics and control, and vibration and stress analysis. In the following pages, the research projects, which were in progress or were initiated during the 2000-03 academic years, are described in summary form. Included in the project descriptions are the names of faculty members (caps) conducting the research, the names of research assistants, and the names of the sponsoring agencies.

DEVELOPMENT OF MULTI-OBJECTIVE CONCURRENT SUBSPACE OPTIMIZATION AND VISUALIZATION METHODS FOR MULTIDISCIPLINARY DESIGN -- Most real- world design problems are complex and multidisciplinary, as there is always more than one objective (cost) function to be extremized in each problem. Hence, the primary goal of this research is to extend the capability of the Concurrent Subspace Optimization (CSSO) method to handle multi- objective optimization problems (MOPs) in Multidisciplinary Design Optimization (MDO). In this study, the framework of Multi-Objective Concurrent Subspace Optimization (MOCSSO) methods have been developed in which each discipline has substantial control over its own objective function during the design process. By means of MOCSSO, an aggregate objective function is not required before solving an MOP. Instead, each subspace optimizes its own objective function while obtaining a Pareto optimum. This is accomplished by incorporating the concept of Pareto optimality into the subspace optimizations.
Another important consideration for large-scale multidisciplinary multi-objective problems pertains to the increasing large amounts of data being generated during the design process. As computing power has advanced, design problems that can be modeled and analyzed have grown in numerical size, dimensionality, and complexity. As a result, engineers often face large and complex datasets. Traditionally, design information has been passed as numerous pages of printed data or in spreadsheet form. It is not always an easy task or even a practical one to analyze such large amounts of data. Therefore, it has become more crucial to develop new methods and tools to understand and interpret complex datasets. Visualization has proven to be a valuable tool in providing the needed increased understanding. In this study, the Multi-Objective Pareto Front Visualization (MOPFV) interface, tailored for the Multi-Objective Concurrent Subspace Optimization methods, has been developed to enable such a need as mentioned above. – C. L. BLOEBAUM , C.-H. Huang

DEVELOPMENT OF A WEB-BASED VISUALIZATION ENVIRONMENT FOR DECISION-MAKING IN MULTIDISCIPLINARY DESIGN OPTIMIZATION -- The analysis and optimization of most engineering and manufacturing systems such as automobiles, aircrafts etc. experience interactions amongst various components of the full system. These interactions are increasingly being handled using distributed design groups. Multidisciplinary Design Optimization (MDO) has evolved to assist designers from different disciplines in steering a product or process design towards its optimum. Visualization is increasingly being used in MDO to improve the product design by assisting the designers in their decision-making. A barrier to sharing visual models amongst designers from different disciplines is the use of different computing platforms to accomplish their tasks. Since the design groups are often separated geographically, a web-based design environment that allows collaboration amongst designers is preferred. This research focuses on the development of a platform independent visualization framework to assist designer in their decision-making while solving MDO problems that could potentially have a physical representation. A physical representation of the design artifact, along with the Dependency Structure Matrix (DSM) is provided. Using this interface, a designer can view components or sub-systems being impacted by changes in other components or sub-systems by means of visual cues. The development of an intuitive interface would allow a designer to trade-off accuracy and efficiency in an instinctive fashion. In addition, using the representation of the product being designed, the designer can better comprehend the impact that changes in a component will have on the overall physical system. A critical portion of this capability is the nonproprietary, platform-independent translation of various design related data into a visual representation. This transformation process provides a capability for collaboration amongst companies or design groups, each using their own internal design tools. Various data associated with the MDO system such as analysis data, geometric data, can be integrated into the representation and handled in an efficient way to be used for collaboration between d esigners. – C. L. BLOEBAUM, G. Agrawal.

DEVELOPMENT OF AN INTUITIVE MULTI-VARIATE MULTI-DIMENSIONAL VISUALIZATION FRAMEWORK -- A visualization methodology is developed in which multidimensional data can be viewed in an intuitive and straightforward manner. Based on this visualization, it is possible to quickly identify ‘good’ regions of the design space for an optimization application, regardless of space complexity. The method requires no dimension fixing. While the potential applications of such an approach are many, in this research we are presently focused on the application to multiobjective optimization, in order to demonstrate it’s usefulness in visualizing n-f space (i.e. for more than three objective functions in a multiobjective optimization problem). The visualization is shown to aid in the final decision of what potential design should be chosen amongst all possible Pareto solutions. While the application here is focused on multiobjective optimization, the research has broader implications of the method, as well as broader potential applications. The method is equally useful and applicable for exploration (as is usually desired in design applications) as well as aiding in interpretation of relationships in existing databases (as in finding correlations amongst data in an economic database or bioinformatics database). – C. L. BLOEBAUM, G. Agrawal.

DECISION SUPPORT TOOL FOR COLLABORATIVE MULTIDISCIPLINARY DESIGN AND OPTIMIZATION USING MULTIPLE SYSTEM DECOMPOSITION DOMAIN -- Design of complex engineering systems often involves decomposition of the complete system into smaller and manageable subsystems or elements. The system can be decomposed either based on physical components, or based on disciplinary analysis or based on the tasks involved in the design. The decomposed subsystems or elements (tasks, analysis & components) are still interdependent amongst themselves. The decomposition and interdependencies within each domain is represented by Design Structure Matrix (DSM). This research effort is intended to understand and analyze the product development process effectively by capturing the correlation between the three decomposition domains, namely the physical domain, analysis domain and task domain. This research will help the designers and managers to capture the effects of changes in one of the domain, onto the other domains of the system. Based on this research, a decision support tool will be built for multidisciplinary design and optimization (MDO) problems. The decision support tool could be used to monitor the design process, and also to estimate the time and cost involved with a change in the design process. The decision support tool will be a web-based platform independent software tool; primarily using XML data transfer standards. This research effort has also focused on development of an XML-based generic data architecture that could be applied to MDO problems by combining optimization data and analysis data in a platform independent format. This XML data format can be used as a foundation for the development of distributed MDO tools by governing the data exchange between disciplinary analysis tools, optimizers and user interfaces. The Golinski’s speed reducer optimization problem from NASA MDO Test Suite is modified as a tightly coupled MDO problem to be used as a test problem for this research. The methodology and decision support tool will also be demonstrated on other MDO test problems. – C. L. BLOEBAUM, S. S. Parashar.

DEVELOPMENT OF A PARETO FRONTIER USING MOPCSSO AND APPLYING UTILITY THEORY TO CAPTURE PREFERENCES – Designing complex systems requires information from many disparate disciplines. While these disciplines all must achieve an overall goal of designing a product, they each have their own objectives (cost functions) that they wish to satisfy. The research area of Multidisciplinary Design Optimization (MDO) deals with the conflicting nature of the different disciplines. Yet, with advances and changes arising in the design process, new methodologies must be implemented to arrive at the optimum design for all subsystems. It is known that while generating a Pareto frontier yields all optimum solutions, it is then up to the designer(s) to chose the final solution. This choosing relies on designer preferences, which is ambiguous. The first goal of this research is to verify that it is in fact possible to generate a well distributed Pareto frontier by implementing concepts of the recently developed Multi-Objective Pareto Concurrent Subspace Optimization (MOPCSSO) method in conjunction with the � - constraint method. Generating a smooth Pareto frontier will assist in satisfying the overall goal of this research. The overall goal is to capture designer preferences on the Pareto frontier implementing concepts from utility theory. -- C.L. BLOEBAUM, J. Galuski

GIANT and BALLISTIC MAGNETORESISTANCE – Research is focused on magnetic multilayers that exhibit the giant magnetoresistance effect and magnetic nanocontacts that show ballistic magnetoresistance. Ongoing studies involve magneto-electron transport across nano-constrictions of atomic dimensions, chemistry of ballistic contacts, and micromagnetic studies. –H. CHOPRA.

BALLISTIC NANOCONTACTS – These are single atom or a few atom large electrical conductors. These quantum electrical conductors are being studied for their electron transport behavior for making magnetic and chemical sensors.—H. CHOPRA.

GIANT MAGNETOSTRICTION EFFECT – Research is focused on synthesis and characterization of GMS thin films and multilayers for mechanical transduction in MEMS. Focus is on attaining high strain susceptibility at low switching fields.—H. CHOPRA.

MAGNETIC SHAPE MEMORY EFFECT – Research is focused on magnetic SMAs for field induced strains (instead of the sluggish temperature dependent shape memory effect). Research includes micromagnetics and dynamics of bulk and thin films magnetic SMAs and their magneto-elastic behavior.—H. CHOPRA.

MULTIFUNCTIONAL STRUCTURAL MATERIALS AND SMART MATERIALS --Structural composites, with matrices including polymers and cement, capable of functions such as strain/damage/temperature sensing, thermal insulation, vibration damping, radio wave reflection, energy storage/generation, etc.--D.D.L. CHUNG. Sponsor: Multiple Sponsors.

ELECTRONIC PACKAGING AND THERMAL MANAGEMENT MATERIALS --Materials for electrical interconnections, electrical insulation, heat transfer, electromagnetic interference shielding, etc.--D.D.L. CHUNG. Sponsor: Multiple Sponsors.

ATTITUDE DETERMINATION - GPS--Research is being performed to develop new and efficient algorithms for attitude determination using Global Positioning System signals. The goal of this research is to develop fully autonomous algorithms that are robust for any initial attitude. Specific issues to be addressed in the research include: 1) provide optimal attitudes even for coplanar baseline configurations, 2) guarantee convergence even for poor initial conditions, and 3) develop computationally efficient algorithms. Work will demonstrate the use of an indoor pseudolite "constellation" to enable relative attitude determination. Pseudolites, which are radio-frequency transmitters that emit signals similar to the GPS transmissions, are a technology that has become increasingly familiar in the past decade. While pseudolites are still a developing technology, which have not yet been demonstrated in an on-orbit space flight experiment, it is perceived that they hold great promise for augmenting the existing GPS satellite-based navigation and attitude determination technology in local-area applications. The goal of this research is to investigate and develop optimal algorithms that can provide fast and reliable relative attitude information of a moving vehicle. --J. CRASSIDIS. Sponsor: NASA-Johnson Space Center.

COMPOUND EYE GPS ATTITUDE-NAVIGATION SENSOR --Research is being performed at NASA-Goddard Space Flight to develop a new sensor approach for attitude determination using Global Positioning System signals. The concept involves the use of multiple GPS antenna elements arrayed on a single sensor head to provide maximum GPS space vehicle availability. A number of sensor element configurations are being considered. In addition to the navigation function, the array is used to find which GPS space vehicles are within the field-of-view of each antenna element. Attitude determination is performance by considering the sightline vectors of the found GPS space vehicles together with the fixed bore sight vectors of the individual antenna elements. The advantages of new GPS attitude sensor include: 1) differential carrier-phase measurements are not required, 2) attitude errors from multi-path can be reduced or even eliminated, 3) integer ambiguities do not need to be resolved, and 4) line biases do not need to be determined. --J. CRASSIDIS, D.A. Quinn and F.L. Markley. Sponsor: NASA-Goddard Space Flight.

INTERNATIONAL SPACE STATION --Determining the extent and location of leaks on the International Space Station (ISS) is vital to maintain the operational status and safety of the station. The first indication of a leak on the ISS will likely be a drop in internal pressure. However, the gas leaving the station will likely cause a reaction force. Research will develop tools to determine approximate locations and sizes of ISS leaks based on measurements from the attitude determination system. The research has two specific goals: 1) determine force and torque inputs from ISS attitude measurements and 2) quantify size and location of leaks from the determined forces and torques. The second item may have multiple solutions. Therefore additional information, such as hatch closures, will be incorporated into the overall system tool in order to help reject spurious solutions.--J. CRASSIDIS. Sponsor: United Space Alliance.

MODEL-ERROR CONTROL SYNTHESIS --Research to develop a new approach for robust adaptive control. This approach, called Model-Error Control Synthesis (MECS), uses an optimal real-time nonlinear estimator to determine model-error corrections to the control input. The estimator determines the model error using a one time-step ahead approach. Control compensation is achieved by using the estimated model-error as a signal synthesis adaptive correction to the nominal control input so that maximum performance is achieved in the face of extreme model uncertainty and disturbance inputs. The MECS approach has many significant advances, including: 1) the determined model is a natural by-product of the state estimator, 2) model parameters need not be updated in order to achieve robust performance, and 3) it can easily handle both time-varying parameter changes in the model and unmodeled disturbance inputs.--J. CRASSIDIS.

SPACECRAFT FORMATION FLYING NAVIGATION --Research is being performed for vision-based attitude and position determination for formation flying applications using a newly developed sensor by Dr. John L. Junkins employing position sensing diodes to determine line-of-sight vectors to optical beacons. The vision-based navigation (VISNAV) system comprises of an optical sensor of a new kind combined with specific light sources (beacons) in order to achieve a selective of "intelligent" vision. The sensor is made up of a Position Sensing Diode (PSD) placed in the focal plane of a wide-angle lens. When the rectangular silicon area of the PSD is illuminated by energy from a beacon focused by the lens, it generates electrical currents in four directions that can be processed with appropriate electronic equipment. While the individual currents depend on the intensity of the light, their imbalances are weakly dependent on the intensity and area almost linearly proportional to the location of the centroid of the light beam in the PSD. Spacecraft formation flying is an evolving technology with many possible applications, such as long baseline inteferometry, stereographic imaging, synthetic apertures, and distinguishing spatial from temporal magnetospheric variations. A significant advantage of distributed spacecraft platforms over a single multifunctional spacecraft is that single point failures can be rectified through replacement of cheaper and smaller spacecraft to maintain mission capability, thus providing a more reliable and robust systems. Many missions (in particular interferometry missions) rely on precise relative position and attitude knowledge in order to maintain mission requirements. To date, most research studies into determining relative positions and attitudes between vehicles have involved using the Global Positioning System (GPS), which restricts the spacecraft formation to near- Earth applications. An application of GPS-like technology to a deep space mission has been proposed, but this requires extensive hardware development and is subject to the generic resolution, and cycle slip. The main objective of the proposed research is to provide a novel, reliable, and autonomous relative navigation and attitude determination system, employing relatively simple electronic circuits with modest digital signal processing (DSP) requirements, and being fully independent of any external system.--J. CRASSIDIS. Sponsor: NASA-Goddard Space Flight Center (through a Cross-Enterprise Technology Development Program grant).

AUTOMATED SPACECRAFT ALIGNMENT AND CALIBRATION ALGORITHMS – This work involves the development of algorithms for:
1) Automated Gyro Calibration (alignment, scale factor, and biases);
2) Automated Three-Axis Magnetometer Calibration (alignment, scale factor, biases); and
3) Automated Fine Sun Sensor Field-of-View Calibration (focal length and focal plane calibration). Batch least-squares methods are being investigated along with an observability analysis. This analysis decomposes the associated covariance matrix using an orthogonal transformation, which provides information on the relative observability between desired quantities, e.g., scale factor versus alignment observability. Algorithms are also being developed for real-time application, which include methods involving sequential least-squares, Kalman filtering and Unscented filtering. Experimental data taken at NASA-Goddard is being analyzed so that performance comparisons can be made between the various proposed methods.—J. CRASSIDIS.
HIGH FIDELITY NUMERICAL MODELING AND SIMULATION OF FIRE SUPPRESSION -- The objective of this research is to develop an advanced modeling and simulation framework for predicting the suppression of large scale fires using water mists and sprays. The modeling is based on Large Eddy Simulation (LES) techniques using probabilistic based subgrid scale (SGS) models to account for multiphase coupling of buoyantly driven turbulence, combustion, suppression thermo-chemistry, droplet transport and thermal radiation heat transfer. The main challenge in controlling large fires is predicting the performance of the delivery system that depends on the understanding of dynamics of flame suppression processes in highly turbulent, strongly radiating, multiphase, combusting flows. One of the goals of this research is to provide a high fidelity predicative tool to simulate these processes. Such a tool will allow fire protection engineers to design better fire suppression systems to insure fire safety for our nations’ critical infrastructures. – P. E. DESJARDIN. Sponsor: National Science Foundation

FLUID STRUCTURE MODELING FOR WALL FIRES -- Up to 60% of the total heat transfer in a hydrocarbon fire comes from thermal radiation. The radiation heat transfer can cause significant degradation of structural integrity and ultimately material failure. The focus of this research is to model the response of composite structures from a pool fire. The activities include development of a thermo-mechanical damage model for composite materials, a near-wall turbulence model for wall fires, and numerical algorithms to couple CFD and FEM based solid mechanics codes together using level set methodologies. The ultimate goal of this effort is to predict failure of a composite structure from a fire. – P. E. DESJARDIN. Sponsor: Office of Naval Research.

NUMERICAL MODELING AND SIMULATION OF METALIZED TWO-PHASE COMBUSTION SYSTEMS – This effort is to examine the ignition and combustion of fine aluminum particles dispersed in a carrier gas containing multiple oxidizing agents. The focus of the research is to develop models for ignition and burning processes of aluminum particles. These particles are often employed for use in the design of explosives and are also used as an additive in propellants to enhance specific thrust. The goal of this effort is to use the aluminum particle models to simulate and understand the flow dynamics of highly energetic shock induced dispersal events. –P.E. DESJARDIN. Sponsor: Sandia National Laboratories

THERMAL AND MECHANICAL PROPERTIES OF RUBBER CONTAINING HOLLOW MICROSPHERES (Syntactic Insulation) -- The motivation for this study is the development of a material for deep-sea diving suits for Navy divers. A major limitation of the material presently used is its loss of thermal insulation value at large hydrostatic pressures. This, in turn, limits mission time. Rubber filled with hollow microspheres has the potential to retain its insulating ability at great depths. However, it must also possess the flexibility of the present suit. Research is considering analytical descriptions of the thermal and mechanical behavior microsphere filled rubber – leading to expressions for the effective thermal conductivities and elastic modulii. Numerical computations are also being performed of the large deformation elastic behavior and associated delamination at the rubber/sphere interface. Measurements of the thermal conductivity at high pressures are being performed using a specially designed apparatus. Mechanical deformation behavior is being characterized by tensile and drape tests. -- J.D. FELSKE, J.C. MOLLENDORF, D.R. PENDERGAST (Physiology).

ANOMALOUS TRANSPORT PHENOMENA -- The specific phenomenon being studied at present may be called ‘heating by cooling’ (or ‘cooling by heating’). For example, starting with a rod uniformly at a high temperature, when one end is cooled we measure that the temperature of the other end first rises before falling. This occurs in all the metals and dielectrics we have investigated. The objective is to explain why this happens by performing more detailed thermal measurements to guide analysis of the fundamental thermoelectric phenomena which underlies the observed behavior. -- J.D. FELSKE, S. George.

MULTI-RECOMPRESSION HEATER (MRH) -- The MRH is a rotary mechanical device designed to cleanly and uniformly heat a gas stream by compression to a few thousand degrees Kelvin. The MRH has potential application to a number of environmental problems including the destruction of hazardous/biohazardous chemicals as well as the formation of chemicals by pyrolysis instead of combustion (thereby minimizing unwanted reaction products). Presently being considered are various fluid, thermal, and mechanical issues: clearances and the detailed gas dynamics of leakage flows; materials selection, thermoelastic behavior, stress levels, bearing design, and cooling requirements. Measurements of compressive heating and destruction of biologicals are being made on a Roots blower. -- J.D. FELSKE, J.A. LORDI, J.C. MOLLENDORF.

ANALYTICAL STUDIES IN RADIATION HEAT TRANSFER  --Studies of present interest include: development of data inversion schemes for analyzing laser light scattering measurements; modeling of the optical properties of nonhomogeneous particles and composite media; analytical and numerical solution of the radiative transport equation; modelling radiative heat transfer in combustion systems; computation of the scattering and absorption characteristics of combustion generated particulates -J.D. FELSKE.

ANALYTICAL STUDIES IN COMBUSTION – Presently, combustion phenomena associated with very small metallic particles is being considered. In particular, the oxidation, melting, vaporization and gas phase combustion of aluminum particles (< 50 micron dia.) is being treated as well as the growth of an attached oxide layer. Study of the development of stresses in the oxide layer due to both growth of the layer and differential thermal expansion is being performed to determine if or when the oxide shell breaks, exposing aluminum directly to the high-temperature environment. –J.D. FELSKE, P. DES JARDIN.

NON-INVASIVE SYSTEM FOR MEASURING THE BIOMECHANICAL PROPERTIES OF SOFT TISSUE -The specific goal of this project is to develop a Virtual Reality based diagnostic system for medical examination of the human abdomen. It is expected that the system could be used in conjunction with telemedicine systems for remote applications.The primary need that will be met by this research is to accurately convey the essential components of abdominal exam information to a distant consultant. Current decision making in emergency telemedicine systems relies on the observed patient examination by a trained assistant at the remote site. Our data shows a high rate of patient transfers from the remote site staffed by nurses and paramedics due to an uneasiness of emergency physicians with this examination's ability to rule out serious disease. Having accurate, sensitive and objective information at the point of decision making by the consultant is essential to avoiding the discharge of a possible appendicitis or other intra-abdominal crisis. - T.KESAVADAS, Mayrose, K.Chugh

PHYSICALLY-BASED MODELING THROUGH A DYNAMIC ATOMIC UNIT APPROACH FOR HAPTIC RENDERING: TOWARDS NON-LINEAR, ISCOELASTIC, ANISOTROPIC BEHAVIOR -The intention of this research is to design a methodology which allows 3D models to be enabled with haptic rendering capability. To provide this capability, the 3D model needs to be voxelized and the mechanical behavior of the body to be simulated, specified. Using the dynamic Atomic Unit Approach, the model can then be hapitcally rendered. The user can build complex hapitcally enabled objects such as a hard body embedded within a soft one, by performing boolean operations of separate hapitcally enabled objects. - Amrita Chanda and T. KESAVADAS

IMAGE GUIDED SURGERY IN NEURO-ENDOVASCULAR PROCEDURES -Assist interventionalists in making decisions about accessibility by providing them with information on vessel curvatures and position and orientation of intervention devices. Endovascular neurologic interventions are increasing in frequency and complexity. However, currently interventionalists judge accessibility using only subjective estimations from 2D angiograms. The goal of this project is to provide the interventionalist with information on vessel tortuosity, accessibility, position and orientation of catheters, angioplasty balloons, and stents relative to vessel walls using angiography data. - T.KESAVADAS, K.Hoffmann, N.Subramanian, Anant Gopal

LIVING ANATOMY PROJECT -In advancing our capabilities in the realm of virtual reality based simulators, the development of haptic technology has been a rate limiting factor. The living anatomy program seeks to obviate the need for such technology by designing physical objects based on anatomical components that feel realistic to the touch. In a virtual environment, the sense of touch can provide a very valuable enhancement towards the immersive nature of the experience. This is more profound in the case of surgical simulators. This is because a surgeon develops mature palpation skills for differentiating between normal and diseased organs and tissues. In the living anatomy system, the physical/virtual object synchronization is achieved by taking a physical model of the organ and a 3 dimensional model of the surface of the model and linking them in real-time using a position tracking system. For example a physical model of the spleen was created using a platinum-based pourable silicone. This material was chosen as it roughly approximates the tactile qualities of an in vivo spleen. The physical model was then scanned using a laser scanner and a triangle mesh representation of the model is created out of this scanned data. This mesh is texture mapped to look like an intra-operative spleen. A “Flock of Birds” DC magnetic spatial tracking system is used to register the physical object’s position onto the virtual object. Students and surgeons will benefit from this new training technique for instruction in organ palpation and visualization.- T.KESAVADAS, David Fineberg, A.Kamerkar, N.Subramanian

UB VIRTUAL SITE MUSEUM - The purpose of this project is to document and publish a uniquely comprehensive report on ancient assyrian palace, by bringing together, for the first time, all new, updated and extant materials and research using leading-edge computer graphics technologies, and to create a multimedia interactive educational and scholarly research tool with applications for colleges, universities, independent scholars, and museums. The main advantages are:
Preservation of Cultural Heritages
Reconstruction of Precise and Authoritative Ancient Site Building
Efficient Education/Research Tool -T.KESAVADAS, S.Paley, Y.Kim

INFORMATION PROCESSING FOR INTEGRATED OBSERVATION AND SIMULATION BASED RISK MANAGEMENT OF GEOPHYSICAL MASS FLOWS –Develop an integrated visualization system for visualizing geophysical mass flows interacting with GIS database and simulation. The risk of potential volcanic eruptions is a problem that public safety authorities throughout the world face several times a year. Computer simulations of volcanic phenomena permit analysis of loss of life and disruption of infrastructure that is not possible today. Flow models are useful to forecast the movement of volcanic materials on or above the surface. Applications of such models include pre-crisis understanding of hazards and developing risk maps, real-time crisis assistance and management, and post-crisis reconstruction and distribution of aid. Visualization of volcanic phenomena is useful for analysis of various types of flows that range from slow-moving lavas and debris flows saturated with water to high-speed hot pyroclastic flows and blasts. We are adapting several computer codes to parallel computing and developing visualization and communication architecture to assist in risk assessment. Visualizing large data sets is an important step in many computational problems. But the data sets produced by some of today’s computational environment often exceed terabytes. To effectively visualize such a huge dataset we need either high-end machines operating in parallel or post-processing the data to reduce the size of data set that is finally visualized. Current research has been focused mainly on the following four areas: Data Reduction, Data Comprehension, Interactive Techniques and Architecture/Systems. Graphics load must be controlled by an adaptive surface triangulation and by taking advantage of different levels of detail. The ultimate goal of uncertainty visualization is to provide users with visualizations that incorporate and reflect uncertainty information to aid in data analysis and decision-making. Techniques have also been developed to organize objects in complex. - A.Patra, T.KESAVADAS, P.Nair et. al

POST DISASTER MONITORING --The goal of this project are:
- Monitoring Earthquake or Post-disaster Situation with GIS/GPS
- Having Multiple Choice of Optimal Path to Nearest Hospitals
- Implementation of Large Amount of Data and its Fusion
The purpose of this project is to simulate monitoring of disaster and its relief situation for a control center. When disaster occurs, there normally is huge amount of data flowing into the control center and thus data fusion process is needed for monitoring and relief action, such as data visualization, status awareness and decision making. Main technique includes geo-referencing GIS data, real-time optimal path simulation and multiple optimal path direction in immersive virtual environment. - James Llinas, T.KESAVADAS, Y.Kim , et. al

HAPTIC BASED MULTI-PURPOSE GRINDING SIMULATOR - Material removal operations such as polishing and grinding appear in a variety of fields. This projects aims at creating a haptic based simulator for these operations. Polishing and grinding operations are used in a variety of fields ranging from medical applications like dentistry and orthopedics, to machining operations on metals. These operations are labor-intensive and usually require high level of skill. It is not always viable or possible to train new operators directly on a real specimen for a variety of reasons. In the case of dentists for example, training would depend on the availability of a volunteer or on physical prototypes that are replicated using various artificial materials. Artificially created specimens that are most commonly used to train students are rarely able to simulate the feel of a real specimen that is often critical to the application. The recent onset of sophisticated haptic devices, capable of delivering precise and controllable forces has opened new avenues for the use of computer simulations to replicate these complicated tasks. In our research we aim to combine these new haptic technologies and ever growing computational power to produce training tools that are accurate, realistic and most importantly affordable. A terrain modeling method called Heightmaps is used to replicate the surface roughness. In this method a digital image of the work piece is converted into a 3-D heightmap. Analyzing each pixel of the image relative to its surroundings and assigning it with a height leads to the creation of the heightmap that is imported into the haptic model. The surface roughness can now be felt using the PHANToM haptic device. Some screenshots of the process are shown below. A real-time analysis of the input forces, validated by the force model is used to modify the texture and enhance realism. This gives the user a sense of material removal. The rate of removal is governed by a variety of factors like input force and tool attributes like speed, depth of cut, etc. -T.KESAVADAS, A.Balijepalli.

VIRTUAL FACTORY PROJECT -The UB VR-Fact! provides an manufacturing environment for:
- Modeling before building
- Simulating before you producing
- Anticipating and solving problems before they occur
VR-Fact! is an interactive virtual factory development software developed as a part of a research to explore the applications of Virtual Environments (VE) in the area of manufacturing automation. VR-Fact creates digital mock-up of real factory shopfloor. Designers can drag and place modular machines in the factory to study issues such as plant layout, cluster formation and part flow analysis. For the design of this shop floor the user can interactively choose the machines which are required to manufacture a set of parts. Furthermore, the VR walk through environment provides a unique tool for studying physical aspects of machine placements. Mathematical algorithms are used for generating independent manufacturing cells. This approach simultaneously identifies part families and machine groups and is particularly useful for large and sparse matrices. The biggest advantage of using VR-Fact! for the factory design is that it supports the user in planning space or logistical issues by interactively moving and relocating the machines after the simulation has been carried out. With integration to all levels of product development and production cycle, the virtual factory provides unique environment for achieving the above goals. The VR-Fact! software was developed on a Silicon Graphics ONYX 2 computer and can be visualized using stereo head mounted display and Crystal Eye stereo glasses. This model also has supporting software for viewing on a Fakespace Boom3C. The software can also be implemented on Pentium based PCs.-T.KESAVADAS, M.Ernzer, L.Lefort, S.Narayansamy, A.Sudhir, C.Singh, Y.Menezes, A.Shedge

UNCERTAINTY VISUALIZATION AND HAPTICS IN THE SCOPE OF MINEFIELD DETECTION - To develop an immersive environment for Uncertainty Visualization for minefield detection using visual, audio and haptic techniques. Visualized data often have dubious origins and quality. Different forms of uncertainty and errors are also introduced as the data are derived, transformed and interpolated, and finally rendered. In the absence of integrated presentation of data and uncertainty, the analysis of visualization is incomplete at best and often leads to inaccurate or incorrect conclusions. Whenever we have a large amount of data, it becomes quite difficult to interpret the data using visual senses alone. In such a situation, it is essential to make use of the sense of touch and hearing. This project deals with recreating a Virtual Minefield Environment using Uncertainty Visualization Principles. The Graphical User Interface has been developed using Open GL / C++ and GHOST SDK. and enhanced by incorporating Graphics, Sound and Haptics.-T.KESAVADAS, A.Bisantz, A.Kamerkar, P.Bhide, S.Basapur

COOPERATIVE PAYLOAD TRANSPORT BY ROBOT COLLECTIVES -- Our goal is to design, analyze and implement a flexible, scalable system of multiple mobile manipulators, that are individually autonomous but can team up to cooperatively transport large payloads and to perform tasks that simply cannot be performed by a single mobile platform. Such frameworks for remotely controlled or remotely supervised cooperation of multiple autonomous modules have many applications from uneven terrain exploration to material handling on the shop floor.-- V. KROVI.

A LOW-COST HOME-BASED TELEREHABILITATION ENVIRONMENT -- We have developed a proof-of-concept prototype Telerehabilitation Environment to serve as an integrated low-cost home-based diagnostic/therapeutic tool for both initial assessment and subsequent motor rehabilitation of upper-limb dysfunction, in the context of driving which is one of the more important activities of daily living.--V. KROVI, N.FISHER.

COMPLEX SYSTEMS MODELING AND REALIZATION --The design and realization of complex systems requires continuous interaction of multiple designers, design teams, companies, and their associated computer-based decision support tools. In this work, different game theoretical constructs are developed to model these interactions based on the level of cooperation among the decision-making entities and inherent organizational structure. The effect of various concurrent and sequential relationships on final product structure are studied and compared, and are used to re-engineer existing computational and organizational structures in industries that design complex systems.--K. LEWIS. Sponsors: National Science Foundation and NASA Langley Research Center.

DECISION SUPPORT AND VISUALIZATION TOOL DEVELOPMENT -- The primary research questions being addressed pertain to the development of visualization techniques that can be effectively used in collaborative design environments. These environments are to be used to make multiobjective decisions under uncertainty and to enable rapid trade-off decisions by geographically distributed participants in the context of Rapid Virtual Prototyping. Design decision-making is largely multiobjective in nature and characterized by various forms of uncertainty. Developing decision support tools, to support the tradeoffs inherent in these types of design environments is the focus of this work.--K. LEWIS, C.L. BLOEBAUM Sponsor: National Science Foundation.

FLEXIBLE SYSTEMS DESIGN --The design of flexible systems involves designing systems that are able to adapt to their surroundings based on new requirements or a chance in operating conditions. These flexible systems allow for one system to perform multiple functions in an optimal sense. Designing flexible systems requires measures of flexible, integrating profit benefit and demand theory with engineering decisions, and developing evolutionary computing techniques to embody the systems in a optimization-driven design process.--K. LEWIS.

DECISION-BASED DESIGN --Decision-Based Design is based on viewing design as a series of decisions, which may be under risk, uncertainty, or multi-attribute. Concepts from decision theory, game theory, statistics, and operations research are being studied as decision support tools in design.--K. LEWIS. Sponsor: National Science Foundation.

AGENT BASED DISTRIBUTED DESIGN -—Large design companies typically use a number of suppliers to support the design and manufacture of large systems. However, when the suppliers are distributed and have limited information, they act as design agents making decisions with incomplete information based on their own incentives. Modeling this scenario using game theory and concepts from decision theory (group and individual rationality) to supply design decision support both descriptively and normatively is the focus of this research.--K. LEWIS.

FEASIBILITY ASSESSMENT IN VEHICLE DESIGN ---In this project, we are developing tools and methods to effectively populate optimal multi-objective frontiers of vehicle performance characteristics, and determining concept feasibility using information from both the design space and performance space. Together, these will provide feasibility assessment capabilities both from a performance and engineering perspective.—K. LEWIS. Sponsor: General Motors.

MULTIATTRIBUTE DECISION MAKING IN CENTRALIZED AND DECENTRALIZED DESIGN --- In this project, the focus is on multiattribute decision making, where the decision is being made by a single centralized decision maker or a decentralized set of decision makers each responsible for a single attribute. We are extending an approach to multiattribute decision making under certainty to conditions of uncertainty and robustness by ensuring consistency and transitivity within the stated preferences of the decision maker. We are also developing provable conditions for convergence and divergence of decentralized design processes. Lastly, we are using these conditions, to study the interaction and balance between individual and group rationality in decentralized design processes:.—K. LEWIS, T. SINGH. Sponsor: National Science Foundation.

VALIDATION IN ENGINEERING DESIGN --- There are a seemingly endless list of decision methodologies and tools that have been developed over the past three decades. However, it could be suggested that there may never be one all encompassing decision support methodology considering that companies that make use of such tools, have different objectives and philosophies. Nevertheless, there should still be some criteria by which to judge these proposed decision support tools; to assure that their use will consistently yield good decisions, i.e., that these methods are valid. Identifying the criteria to validate decision support methods is the underlying motivation for the research presented herein. In addition, a number of decision support methodologies (e.g., House of Quality and Suh’s Axiomatic Design) are critically evaluated under the given definition of validity. -K. LEWIS. Sponsor: National Science Foundation.

BOUNDARY LAYER SEPARATION --Solutions of the Prandtl's boundary layer equations near the point of separation are studied. The question of existence and uniqueness are investigated. Simple models will be constructed to exhibit the separation phenomena. Numerical methods will be established to solve the boundary layer continuation problem including the point of separation. -C.S. LIU.

STABILITY OF HYPERSONIC BOUNDARY LAYER --An analytic approach to the stability analysis is developed based on the WKB method. It is applicable to both insulated walls or walls with heat transfer. Using this model, it is also possible to extend the analysis to include the effects of pressure changes, such as in a corner. -C.S. LIU, D.R. Bower. Sponsor: CalspanUB Research Center.

NONLINEAR RESPONSE OF HYSTERICALLY DAMPED SYSTEMS -- DAMPERSare known to be very effective devices in earthquake engineering. By using nonlinear dynamic system methods such as the averaging method, the response of hysterically damped systems is analyzed with emphasis on base isolation systems, and will render a more effective nonlinear model for practical engineers. -C.S. LIU.

TURBULENT TRANSPORT OF A PASSIVE SCALAR IN GRID TURBULENCE --A better understanding of the diffusion of passive scalars in turbulent flows has important applications in engineering, atmospheric and oceanic sciences. Some examples are improving the mixing efficiency in combustion devices, the dispersion of pollutants in the atmosphere, salinity and temperature fluctuations in the oceans. Some features of the mixing and dispersion rates of scalar contaminates in turbulent flows are likely to be understood by studying the passive scalar wake behind a line source in homogenous turbulence. Numerical simulations are conducted to study the structure and development of the scalar wake produced by a single line source in decaying isotropic turbulence. The structure of the scalar wake will be studied by analyzing each term in the transport equations for scalar moments. This is particularly useful for assessing the behavior and predictions of different turbulent closures.--C.K. MADNIA, D. Livescu. Sponsor: NSF.

RELIABLE CHEMISTRY MODELS FOR ANALYTICAL MODELING OF TURBULENT COMBUSTION --A stumbling block in mathematical modeling of turbulent reacting flows is the mechanism of turbulence-chemistry interactions. The emphasis in almost all previous analytical studies of these flows has been on the turbulence phenomena, not the chemistry. For example, unrealistic one-step reaction schemes have been widely used within the past 10 years. Despite its simplicity and computational convenience, one-step chemistry models are unable to capture many important phenomena such as flame ignition, extinction, propagation, intermediate radical species concentration and soot formation. The objective of this work is to develop and implement more reliable chemistry schemes in theoretical-computational investigations of turbulent combustion phenomena. The implementation of “full kinetics schemes'' for computations of hydrocarbon combustion is impossible; but it is possible to implement “reduced kinetics schemes”. Reduced schemes imply simplified chemistry mechanisms deduced from the full chemistry. Several of available reduced kinetic schemes are being utilized in mathematical-computational modeling of hydrocarbon diffusion flames in various turbulent flow configurations --C.K. MADNIA. Sponsor: American Chemical Society.

TURBULENCE-CHEMISTRY INTERACTIONS IN REACTIVE TURBULENT SHEAR FLOWS --Turbulent combustion is a complex physico-chemical phenomenon that is spatially three-dimensional and is of transient nature. This phenomenon has been the subject of intense research within the past sixty years and continues to be of high priority in view of the worldwide concern about energy and pollution control. Since the mean shear is present in most of the turbulent flows, the study of homogeneous shear flows can reveal many features of compressibility in practical turbulent flows. The influence of chemical reaction on the development of compressible turbulent shear flows in being studied by solving the Navier-Stokes equations, the energy equation and the transport equations for the reactive scalars. A single-step exothermic irreversible Arrhenius reaction is considered. --C.K. MADNIA, D. Livescu. Sponsor: NSF.

MODELING AND DNS OF HYDROCARBON FLAME-VORTEX INTERACTIONS --The laminar diffusion flame-vortex ring configuration is a simple configuration that contains some of the key physical characteristics of turbulent diffusion flames. The ongoing investigation can help us extricate some of the fundamental questions that are central to the turbulent diffusion flame processes. The main objective of this study is to gain fundamental understanding of the physicochemical processes that occur during the combustion of non-premixed laminar hydrocarbon fuels. The main thrust of this research is to conduct direct numerical simulations (DNS) of non-premixed flame-vortex interactions with inclusion of "realistic" chemistry models. The DNS generated results will then be used to develop kinetic mechanisms for unsteady combustion systems.--C.K. MADNIA, C. Safta. Sponsor: ACS-PRF.

DIFFUSION FLAME-VORTEX RING INTERACTION: A NUMERICAL STUDY --A laminar vortex ring is generated by a jet of fuel-inert species mixture that enters a quiescent medium of the same composition and temperature. The fully formed vortex ring interacts with a quasi-steady diffusion flame that is perpendicular to the ring's axis. Direct numerical simulation is used to solve the compressible Navier-Stokes equations coupled with the energy and the species equations. The Arrhenius-type reaction between the two chemical species is taken to be second order and irreversible. Both finite rate and infinitely fast chemical reactions are considered.-- C.K. MADNIA, C. Safta. Sponsor: ACS-PRF.

OPTIMIZATION METHODS and APPLICATIONS -- this is a continuing effort in the study of optimization methods and their application to mechanical engineering problems. Past research in optimization methodology has considered a wide variety of optimization methods and applications. Recent efforts have been devoted to optimization in the PC Windows environment and have included: a library of optimization methods supported by graphics, visualization methods for exploring optimization problems, and an optimization interface to CAD/CAE packages -- R.W. Mayne, N. Khedkar, U. Bharadwaj, S. Erande.

PROGRAMMING FOR CAD/CAE PACKAGES -- recent projects in this area have considered the programmability of AutoCad, ProEngineer and Unigraphics. We have also developed an application using Visual C++ to perform automated optimal design and interact with CAD/CAE packages through spreadsheet formatting. The purpose of these efforts is to use existing CAD/CAE packages to study the complete automation of the design process from engineering performance requirements through optimization, analysis, design modeling and drawing -- R.W. Mayne, H.P. Qi, N. Sane, S. Sirsikar, S. Erande.

DISTAL FEMORAL FRACTURE REPAIR —Conventional fracture repair plates are inadequate for fractures of the distal femur. A new device is being investigated experimentally and compared to several others.—J. MEDIGE, L. Bone, J. Bustillo, D. Schlatterer.

FORCE TRANSMISSION IN THE WRIST —The irregularly shaped bones of the human wrist are subjected to widely varying forces depending on anatomical position. We are planning to quantify some of these forces particularly in the scaphoid during flexion/extension, radial/ulnar deviation, and pronation/supination.—, B. Sampson, O. Moy.

ASSESSMENT OF FUNCTION IN SMALL ANIMALS USING AN INSTRUMENTED WALKING TRACK —To study the recovery of nerves after injury and repair, we have constructed a walking track for small animals which contains a force plate in its floor that is capable of measuring force vectors in three dimensions. This apparatus can be used to study normal and abnormal gait, involving injury to bones, ligaments or muscles as well.—J. MEDIGE, D. Blakeney, C. Howard, O.Moy.

THE USE OF ULTRASOUND TO PREDICT BONE PROPERTIES --Ultrasound velocity and attenuation are being used to predict various mechanical and densitometric bone properties. Separate studies involve variation with orientation to assess anisotropy, rate effects, and combinations of parameters in human and bovine cancellous bone. Relationships are determined with values obtained by CT scanning, weight and volume measures, and mechanical testing of various bones and specimens.--J. MEDIGE, S. Han, J. Davis, K. Faran.

HOLOGRAPHIC PARTICLE IMAGE VELOCIMETRY (HPIV) – Research and development at the Laser Flow Diagnostics laboratory (LFD) has transitioned from film based holography to digital holography. Integrated HPIV systems combining in-house software and off-the-shelf hardware are now being used routinely in the fluid dynamics and imaging research in the LFD. Ongoing research at the LFD is continually improving the digital HPIV system algorithms and easy of use and is riding on the wave of digital imaging sensor development. Current fluid dynamics investigations using digital HPIV includes: development and validation of a unique experimental facility and Direct Numerical Simulation capability to investigate statistical properties of particles in turbulence, the quantification of the hemodynamics of cerebral aneurysms, and holographic imaging techniques for micro biological applications. --H. MENG. Sponsor: NSF, NASA, NIH.

HEMODYNAMIC INTERVENTION IN CEREBRAL ANEURYSMS --Hemodynamic intervention is a promising endovascular treatment for intracranial aneurysms. However, little is known about hemodynamic and biological responses of realistic aneurysms to such intervention. Within the Hemodynamics Laboratory at the Toshiba Stroke Research Center ongoing research is quantitative our understanding of the hemodynamic factors that induce favorable changes in the aneurysm pathology. This ongoing collaborative effort involving neurosurgeons, medical physicists, microbiologists and engineers is working on understanding this challenging disease and developing more effective treatment paradigms. Optical flow diagnostics tools such as Laser Doppler Velocimetry, Stereoscopic Particle Image Velocimetry and Holographic PIV are being teamed up with Computational Fluid Dynamics (CFD) numerical experiments to quantify the blood flow dynamics. A range of molecular biology techniques looking at gene expression, vascular remodeling factors and histology are being employed to quantify and correlate the biological response with the hemodynamics. – H. MENG. Sponsor: NIH, NSF.

UNDERGRADUATE BIOENGINEERING DESIGN PROJECTS —The main output goal of this activity is to custom-design and construct devices to aid the disabled. Additionally, a specific objective is to provide a meaningful design experience for Engineering Undergraduates that will directly aid specific disabled individuals. This real world experience gives students a sense of accomplishment and pride while serving the community and increasing student interest in Graduate Education.—J.C.MOLLENDORF, Sponsor: National Science Foundation.

DESIGN AND TESTING OF A TOTAL DIVER THERMAL PROTECTION GARMENT —The aim of this program is to develop a proof-of-concept diving suit that combines passive and active technologies to protect divers in warm and cold water while wearing thermal protective gear or Chemical Warfare Gear. This garment has seven principal components that will be integrated: super insulation, a zoned total body liquid cooling and heating suit, heat storage capacity, active heating or cooling, a heat exchanger to dump excess heat, rechargeable power supply, and a physiological monitoring system. These elements would be combined into a diver thermal protection suit that will have durability and protective characteristics to meet the needs of Navy divers.—J.C.MOLLENDORF, CO-Pl, Dr. David Pendergast, Pl. Sponsor: Office of Naval Research.

NONLINEAR IDENTIFICATION --Most identification techniques require that the form and order of the dynamic model equations be assumed, and then the constant parameters in the dynamic equations are estimated using measurements. A technique that does not require a prior assumption of the model form and order is being developed and will be utilized to aid in identifying the nonlinear behavior of large space truss joints. -D.J. MOOK.

CONTROL OF NONLINEAR SYSTEMS --Optimal linear feedback of linear state-space systems is well known, and is typically found from solution of a Riccatti equation. This project is investigating various techniques for determining an optimal linear or nonlinear feedback law for a nonlinear system.--D.J. MOOK.

SPACECRAFT ATTITUDE ESTIMATION AND IDENTIFICATION --Standard spacecraft attitude estimation is performed using either a large complement of attitude and attitude rate sensors, and/or a Kalman-filter algorithm. In either of these approaches, the accuracy is limited in instances of sensor failure or a poor dynamic model. This project investigates the use of nonlinear identification techniques to determine on-orbit accurate attitude dynamic models for the SAMPEX spacecraft. Actual flight data from the SAMPEX spacecraft is made available through an agreement with NASA Goddard Spaceflight Center. SAMPEX is the first of the new Small Explorer (SMEX)-class satellites and was launched into a low-earth orbit in July 1992.--D.J. MOOK.

INFORMATION PROCESSING FOR INTEGRATED OBSERVATION AND SIMULATION BASED RISK MANAGEMENT OF GEOPHYSICAL MASS FLOWS -- This project involves the development of algorithms and tools for distributed high-end simulation of avalanche type hazard events, using the best available and suitable newly developed schemes; a major outcome of this project is the TITAN toolset incorporating the best available numerical methodology and physical modeling for hazardous geophysical mass flows. Current and future work in this effort will include the incorporation of uncertainty into the parameters and inputs used for these computations. —A.PATRA, Sponsor: NSF

PARALLEL ADAPTIVE LAGRANGIAN DISCONTINUOUS GALERKIN METHOFS WITH AN APPLICATION TO SIMULATION OF PEDIATRIC BRAIN INJURY -- In this project we are developing highly accurate parallel adaptive Lagrangian discontinuous Galerkin techniques that will be used in the development of high fidelity simulation tools for investigation of pediatric brain injury mechanisms and preventive strategies. These schemes will enable the use of higher order approximations to obtain accuracies that are O(h^p) and O(del t^k), h,p,k > 1 are the usual finite element mesh parameters and t is the time step.—A. PATRA, Sponsor: NSF

MODELING AND SIMULATION OF CRS SYSTEMS -- In this project we are developing a set of validated computer models of child restraint systems for use in investigation of pediatric crash injury and development of better CRS systems. —A. PATRA, Sponsor CENTIR/ CUBRC.

DEVELOPMENT AND ANALYSIS OF NEW METHODOLOGY AND DEVICES FOR NON-THERMAL PASTEURIZATION OF FLUIDS -- In this project we are developing and analyzing a set of devices for efficient non thermal pasteurization of a range of fluids based on the UV based SIAD process and a new pump design.—A. PATRA, Sponsor NYSTAR/Synergena Inc.



DRIVER-VEHICLE PERFORMANCE ENHANCEMENT IN INCLEMENT CONDITIONS --This project focuses on development of technology to assist drivers in poor driving conditions such as foggy or icy conditions. To evaluate this technology, a high-fidelity driving simulator has to be developed to study the performance of the human-in-the loop system. A virtual reality based approach is used to generate the visual audio and proprioceptive cues for the driver.--T. SINGH, T. KESAVADAS, R.W. MAYNE

ROBUST CONTROL OF NONLINEAR SYSTEMS --Modeling uncertainties which are present in any system representation have tempered the performance of controllers designed to meet stringent specifications. These uncertainties include errors in model parameters and unmodeled dynamics. The effect of parametric uncertainties is accentuated when the controllers are required to switch between their limits as in time-optimal and fuel/time optimal controllers. This work focuses on developing techniques to design robust controllers for nonlinear systems subject to control constraints.--T. SINGH.

NONLINEAR CONTROL OF ELECTROHYDRAULIC SERVO VALVES --In the (inevitable) presence of flow saturation in the first stage of an electro hydraulic servo valve, the dynamics of hydraulic systems become nonlinear. This fact and the dependence of the flow characteristics on the pressure drop across the load, lead to unsatisfactory results by using the linearized system dynamics, especially when pressure control has to be done. In this research, several approaches capable of controlling nonlinear hydraulic systems are investigated. A saturating controller which takes account of the input saturation, a sliding mode controller based on the nonlinear system dynamics for tracking in continuous domain as well as in discrete time, and a fuzzy controller that does not require exact knowledge of the controlled system.--T. SINGH.

REPETITIVE CONTROL --There are numerous systems that are subject to periodic disturbances. Some applications include hard disk drives and CD players where the non-coincidence of the geometric center of the disk and the center of rotation results in a periodic disturbance where the dominant frequency is the speed of rotation of the disk. Other applications include robots performing the same operation repeatedly. Repetitive control is an Internet Model Control approach that permits the rejection of such disturbance. This research project focuses on developing control techniques that are robust to uncertainties or variations in the periodicity of the disturbance. --T. SINGH.

ITERATIVE LEARNING CONTROL --This is a feed-forward control technique that is used for high precision control of systems undergoing repetitive tasks. At the end of every iteration, the tracking error is used to update the feed-forward controller with algorithms that guarantee convergence. This research focuses on development of filters for the learning part of the iterative controller to achieve performance objective such as rapid convergence, robustness to and variations in system parameters.--T. SINGH.

SIMULTANEOUS FEEDBACK/FEED-FORWARD CONTROL DESIGN --Extensive work has been carried out related to the design of feedback controllers for vibrations attenuation of maneuvering systems. Over the past 10 years a large body of literature has also evolved related to the pre-filtering of reference input for vibration attenuation. These two design techniques have evolved independent of each other. This work focuses on the integration of the design of the feedback and the feed-forward controllers.--T. SINGH.

HYBRID FILTERS FOR TARGET TRACKING – This work focuses on the development of a filter that permits tracking on a user specified profile. This filter is proposed to be used in conjunction with a Kalman filter to permit tracking maneuvering targets. The unscented filter will be used for the estimation of the covariance matrix.--T. SINGH.

CONTROL OF FRICTIONAL SYSTEMS —Friction is ubiquitous and precise position control of systems such as robots, machine tools, hard-disk drives, cranes, etc. that require friction to be accounted for. Techniques which can damp out vibrations of systems subject to friction are developed in this work.—T. SINGH.

AUTONOMOUS ROBOTICS —The goal of this work is the development of tools for a multi-sensor robot to construct a map of its environment via Data Fusion and plan a path for the desired goal.—T. SINGH.

LP BASED ROBUST CONTROL DESIGN —To exploit the strength of linear programming (LP), thus work endeavors to design controllers which are robust to modeling uncertainties by approximating the norm with linear hyperplanes.—T. SINGH.

THERMOMECHANICAL MODELING OF SLIDING CONTACTS --the modeling of engineering surfaces, with roughness, near-surface gradients in mechanical properties and complex chemical layers, represents, in many respects, the last frontier of mechanical design. We are using combined computational mechanics approaches and experimental studies to advance our understanding of such contact problems and to develop advanced computational tools for engineering analysis and design. The thermal aspects of the problem, coupled with elasto-plastic deformations significantly push the boundaries of current computational capabilities. Fast convolution algorithms applicable have been developed in order to make the solution of large problems practical. --A. SOOM, G.F. DARGUSH, N. Kania, M. Grigoriev, C. Lee, J. Smith. Sponsor: NSF.

MODELLING OF TURBULENT FLOWS --in attempting to find a universal theory to predict various turbulent flows, researchers are utilizing equations involving higher order correlations in fluctuating velocities and pressure. Hence, dynamic equations for the Reynolds stresses are solved in addition to the mean momentum equations. Improvements are sought for the closure relations for the unknown correlations in the dynamic equations. Numerical solutions are carried out for shear flows (jets, wakes, plumes, etc.) and comparisons are made between calculated and experimental results to verify the closure hypothesis. -D. TAULBEE.

INCREASING FRACTURE TOUGHNESS OF POLYMER COMPOSITES --results on pullout of ductile Copper wire fibers in epoxy has indicated the large toughness increment achievable from ductile, properly shaped and properly anchored fibers. Surface treatments and fiber shaping has been used to improve a variety of properties including fast fracture toughness, impact toughness, and EMI shielding to create a multifunctional material. An active predictive method using FEM with various interface models has been formulated? to scan over a variety of parameterized end shapes and confirms the experimental results . --R.C. WETHERHOLD, A. PATRA, R. Bagwell, J-H Tsai, Sponsor: ARO.

SURFACE MODIFICATION OF METAL FIBERS --Earlier results indicate that then metal fibers are bonded to a thermoset polymer, additional toughening contribution can be obtained if small, discontinuous zones of matrix adhere to the fiber. Efforts are proceeding with the application of small zones of dissolved polyamines such as APS to the fiber surface so as to assure local, discontinuous chemisorption and thus the formation of local asperities which will contribute pullout work without fully bonding the fibers to the matrix. --R.C. WETHERHOLD, J.Parks,Sponsor:ARO

MAGNETOSTRICTIVE MULTILAYERS —multilayers comprised of alternating deposited layers of TbFe and FeCo display an improved magnetostrictive susceptibility and their behavior can be strongly influenced by annealing conditions and by stress biasing. An adapted laminate analysis has been formulated to understand the nature of magnetoelastic coupling and how it might be adjusted to improve results. This analysis has been extended to include the dynamic behavior of film-substrate plates. Experiments to determine the optimal stress biasing to produce optimal susceptibility are proceeding. --R.C. WETHERHOLD, H. D. CHOPRA, V. Guerrero. Sponsor: NSF.

CHANGES IN CHONDROCYTE VIABILITY AND ITS RELATIONSHIP TO ARTICULAR CARTILAGE SOFTENING IN A RABBIT MODEL OF OSTEOARTHRITIS --Articular cartilage has a limited capacity for healing due to the avascular nature of the tissue, the lack of mesenchymal stem cells, and the highly specialized nature of existing chondrocytes. Treatments like abrasion chondroplasty, subchondral drilling, and micro fracture technique, introduce blood supply and mesenchymal cells that differentiate into chondrocyte-like cells. However, when fibrocartilage is formed as a result of the mesenchymal differentiation, it has inferior function when compared to hyaline cartilage, due to the increased ratio of Type I to Type II collagen. The hypothesisis in that introduction of articular cartilage and cancellous bone paste into a cartilage defect will stimulate mesenchymal cell differentiation into the more specific articular chondrocytes that can produce and maintain a functional hyaline cartilage. The objective of this research is to compare the cartilage renewal that occurs when using a paste-graft technique with normal intact articular cartilage and the healing that occurs after traditional subchondral drilling—ISRAEL ZIV, Madhura Gole.

OSTEOCHONDRAL AUTOGRAFT TRANSPLANT SYSTEM (OATS) --In early osteoarthritis, OATS may be used to replace damaged cartilage in synovial joints. The autograph OCP (Osteochondral Plugs) are harvested from a non-weight bearing surface with a thinner and weaker bone/cartilage structure that may fail when put under high load. Allografted osteocartilaginous plugs taken from a weight bearing area of donor may be a solution to this problem. However, the supply of fresh allografts is limited and current storage techniques may interfere with cartilage cell viability. Improved methods of preservation are needed to enhance the use of allografts as an alternative to autografts. The objective of this study will be to compare the effects of glycerol vs. dimethyl sulfoxide (DMSO) on cartilage cell viability when used as cryoprotective agents on osteochondral allograft plug (OCP) transplants in the knee. Sponsors: Arthrex Inc. (Naples, FL).--ISRAEL ZIV, M. Gole, D. Poulsen.

THE CHANGES IN HIP BIOMECHANICS FOLLOWING TOTAL HIP ARTHROPLASTY (THA) --Component placement critically affects the performance and longevity of total hip replacements (THR’s) and will determine hip biomechanics. Studying the biomechanics, as apparent on hip radiographs, may lead to a better understanding of prosthesis placement and improve the outcome of the surgical procedure. By evaluating the biomechanics of the hip before and after THA and comparing this to the clinical outcome of the procedure, we will be able to determine which parameters are the most important for a successful outcome. To evaluate the biomechanics of the hip after THA, we utilize patients whose x-rays were taken at the Veteran’s Administration Hospital. The x-rays will be digitized and analyzed using Adobe Photoshop and ImageJ, NIH. The femoral offset, neck-shaft angle, proximal femoral length, limb length, abductor moment arm, body moment arm, acetabular index, and height of insertion of the gluteus medius muscle will be analyzed to determine the biomechanics of the hip. The clinical outcome will be assessed using two questionnaires, the Harris hip scoring system and the HOOS system. Initial analysis has shown an increase in the abductor moment arm as well as a decrease in the body moment arm, both contributing to a smaller force acting on the hip joint post-operatively. –ISRAEL ZIV

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