This CD is intended to provide information about significant research/development on various projects across many industries performed on OU's campus. Join us to exchange knowledge and experience, and get acquainted with OU's expertise that is readily available to industry, government and other organizations.
Poster/Slide presentations will emphasize scholarly research/development activities in engineering and computer science, including product design, development and manufacturing in supporting large and small companies.
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Abstract: As embedded control systems (such as those used in automotive and military vehicles) become more complex, so does the problem of comprehending the interdependencies of the system components. While the industry has numerous tools for managing requirements, design and test artifacts associated with an embedded controls system, the task of comprehending the interdependencies of these artifacts and the systems they define is largely left to human intellect and individual experience/expertise. The goal in this research is to develop a knowledge representation system that is capable to learn and adapt to new requirements. The thrust is to implement an artifact management system capable of not only evaluating the quality and correctness of a system but also of identifying potential issues which could lead to recalls or rework before the system is fielded or in many cases, before it is even implemented.
Abstract: The goal of this research is to develop learning machines that attempt to re-generate the automobile crash scene based on the data and patterns captured by the different sensors. The results obtained help identify a-posteriori the reasons for many design failures such as SUV rollover, or any other automobile components failures.
Abstract: Driving safety is a dynamic and complicated issue. Traffic volume, driver behavior, lighting, road conditions, road signs, speed limit, lane change and weather condition make driving environment constantly changing and unpredictable. The purpose of this research is to explore hidden Markov decision processes (HMDP) in order to build an adaptive system (learning machine) that senses the environment, interpret it and perform decisions (act upon it). These systems will assist driver reactions by giving out advices using voice or sending out warning signals.
Abstract: Develop novel data mining techniques to mine the databases from NHTSA and automotive companies in order to identify (or mine) the contributing factors that help predict the probability of automobile part defects in the future design change.
Onur Bay and Debatosh Debnath
Abstract: Three-level OR-AND-OR and AND-OR-EXOR networks can be area efficiently implemented in many complex programmable logic devices (CPLDs). Although millions of such CPLDs have been shipped, very little has been published on how to synthesize circuits for them. Logic synthesis for these CPLDs have been done by using proprietary software tools. The objective of the proposed research is to develop computer-aided design (CAD) software that can synthesize optimized OR-AND-OR and AND-OR-EXOR networks from the given logic functions whose two-level networks are difficult to generate and manipulate.
Imad H. Elhajj, Lidia Mudura, Matthew Bruer,
Abstract: Presently, there are a myriad of virtual reality applications being devised for the full spectrum of disciplines. Of particular interest are military and healthcare applications. The importance of simulators for training becomes clear for critical tasks such as flight or surgery. The procedure we simulated is nasotracheal suctioning. The application developed allows nursing students to practice the procedure providing them with force feedback, an elaborate visual interface, and a variety of auditory cues (sounds and verbal instructions). It allows the practitioner to perform this procedure repeatedly in a safe environment before performing it on a live patient.
Imad H. Elhajj, Melissa Layupan
Abstract: Time-based synchronization is typically used for real-time multimedia applications (i.e. videoconferencing). In this work, we propose an alternative method of synchronization. We synchronize media objects by looking at the content, and their rate of change. The increased number of reference points yields a higher number of successful synchronizations and should result in better perceived quality. The study currently is being conducted on using human subjects to evaluate the perception quality.
Imad H. Elhajj, Jason Gorski, Yuanyuan Chen
Abstract: Rapid advances in the field of sensing and sensor networks are opening the door to many new possibilities. The work presented is related to interfacing a robot being controlled remotely via the Internet with a sensor network. The sensor network measurements are fed back to the operator and rendered in the form of a haptic force. This provides the operator with information regarding the environment and thus more efficient and safe operation. Experimental results are provided to highlight the concepts developed.
- Security Issues of Smart Vehicles
Huirong Fu and Imad Elhajj
Abstract: The demand for road safety, traffic management, and driver convenience continues to increase with the appropriate usage of information technology. However, this evolution has deep implication for security, which has been overlooked so far. In this work, we discuss the role that information security will play, identify the challenges, and outline potential solutions.
Abstract: Research in real time embedded system involves efficient and optimal design for size, power consumption, performance, features, and cost. We analyze the embedded systems for ability to meet critical tasks and also the non-critical tasks. Ability to conserve power by adjusting the task schedule, use of advanced DSP processors and microcontrollers with wired or wireless interfaces to network, analysis of network protocols like CAN (controller area network), design of sensors using MEMs for rugged environment, multiprocessor design for high performance and fault tolerance, are some of the areas of research.
We established Real Time Embedded and DSP system Laboratory with funding from Hitachi America and DSP processor hardware and software from Texas Instruments and Motorola, Real time analysis software from ETAS, and Microsoft academic program.
Faculties involved in the RT system Lab are Dr. Subra Ganesan, Dr. Darrin Hannah, and Dr. Debatosh Debnath. A number of PhD and MS students are working in this area.
Richard E. Haskell, Kevin Van Sickle, and Eric McGrath
Abstract: Biometric authentication is a growing field of importance . The need to correctly identify a person is critical in a variety of applications including financial transactions, secure access control, and border and airline security. This research involves a new biometric authentication system in which a person simply “writes” his or her signature in the air. Inasmuch as one definition of ethereal is airy  we call our system WIPES -- Wireless Identification of Persons using Ethereal Signatures. The WIPES device is worn on the wrist much like a wristwatch. The device contains accelerometers that can measure the x-, y-, and z-components of the acceleration of the device and these values are used to calculate features that are transmitted wirelessly to the host device that authenticates the signature. The hardware used to demonstrate the WIPES concept consists of the Freescale MC13192 Sensor Applications Reference Design (SARD) board  mounted in a small box with a battery. Adding a strap to the box allows the device to be worn on the wrist as shown in Figure 1. Research is continuing to improve and miniaturize the device.
 Kung, S. Y., Mak, M. W., and Lin, S. H., Biometric Authentication, Prentice Hall, 2005.
Dae-Kyoo Kim, Priya Gohkal
Abstract: In this work, we are developing a flexible pattern-based technique for developing UML models of secure systems using access control patterns. The technique uses specifications of access control as a design pattern described in the Role-Based Metamodel Language (RBML). An access control pattern is applied to a UML model of an application to be secured by incorporating the properties of the pattern into the model. Using the technique, an access control pattern can be systematically composed with a model by applying a rigorous composition algorithm. We demonstrate the technique using Mandatory Access Control (MAC) and a model of a simple file system.
Dae-Kyoo Kim, Pooja Mehta
Abstract: In this work, we are developing an approach to checking conformance of UML class diagrams to design patterns. The technique provides a set of checks that evaluate syntactic and semantic pattern conformance. Syntactic pattern conformance is concerned with structural conformance of a class diagram to the structural properties of a pattern.
Semantic pattern conformance is concerned with conformance of invariants and pre- and post-conditions in a class diagram to semantic pattern properties. A class diagram is said to conform a pattern when it acquires both syntactic and semantic conformance.
- 3D Shape Classification Using Conformal Mapping
Abstract: A new method for 3D shape classification based on conformal mapping of 3D meshes is introduced. We propose to conformally map 3D meshes to the domain of unit sphere, which generates geometry images and normal maps over the sphere. Then the spherical harmonic representation of the normal map is used as the feature vector input of the self- organizing map for shape classification. This method can evade the common object center estimation and preserve the geometric details. The results demonstrate that the proposed method can discriminate the collected 3D shapes very well, and is robust to noise, tesselations and pose difference.
- Automatic 3D Image Segmentation of Internal Lung Structures
Abstract: This poster presents a new solution for automatic 3D image segmentation of internal lung structures. We combine the image gradient and intensity information to depress the noise and make level set based segmentation algorithm more stable. The experimental results show that our solution gives good results on the public lung image data.
Lunjin Lu, Jie Ouyang
Abstract: Argument size analysis aims at inferring the relationships between predicate arguments regarding their sizes automatically. The inferred relationships can be used in other analysis such as symbolic constant, loop invariant and termination analysis. The structure of this analyzer is based on the framework of bottom up abstract interpretation. We use polyhedra to represent linear constraints and carry out operations on the polyhedron domain. The Parma Polyhedra Library (PPL) is the tool we use to perform those operations, which brings the benefits of high efficiency, easy to use and built in interface to Prolog systems.
Lunjin Lu, Tim Hayes
Abstract: Call strings are abstractions of execution paths that may occur during the run of a program. These paths are used to take increase the precision of information about execution points in a program. This increased information however, comes with a computational cost. This project aims to provide experimental evidence regarding the computational cost of context sensitive analysis with call strings. This information can be used by logic programming tools, such as analyzers, compilers, and interpreters.
Xuan Li , Andy King and Lunjin Lu
Abstract: Sharing analysis is one of the most well studied analysis for logic program. Two variables share if they bind to terms that contain common variable. This sharing information is important for many application such as automatic parallelization of logic program and occurs-check reduction etc. This work presents a new domain for sharing analysis. The abstract unification is polynomial with respect to number of groups and closure operations are executed on demand after analysis. Several optimizations are considered and hence the analysis is efficient.
Xuan Li and Lunjin Lu
Abstract: This work presents an inversion of the abstract unification operator for forward set-sharing analysis of logic programs. The inverted operator, called a backward abstract unification operator, computes all maximal pre-conditions for a given equation and its post-condition. It is a key operator in a backward analysis. The maximal preconditions are obtained by first calculating a superset of all preconditions and then generating all maximal pre-conditions from the superset. The latter step is transformed to the problem of finding all maximal models of a Boolean formula.
Fatma Mili, Iris Bass and Mark Rossman
Abstract: Sensor networks consist of large sets of sensor nodes distributed geographically to monitor events of interest (e.g. atmospheric changes, appearance of specific objects) or collect data measurements (e.g. temperature, light, pressure) at different locations. Each sensor node generates data records at predefined time intervals. The sum of all the records generated can be seen as a distributed database used to monitor conditions and make decisions. Lengthening the life of the network while maintaining accurate results is one of the challenges of managing sensor networks. We discuss a novel approach in which the network self organizes and allocates activity to nodes based on their assessed information value.
FatmaMili, Swapna Ganekhar
Abstract: A critical factor in the design of successful interactive systems and systems with a human in the loop such as medical equipment, vehicles, and military systems and weapons is the optimal and safe delivery of a set of services. Systems and their interfaces need to be designed so as to minimize the time it takes to perform tasks, minimize the likelihood of human error, and take into account human capabilities and limitations. Performance models can be developed to test design. Because the models are highly detailed, they would greatly benefit from software engineering methodologies such as modularity, reuse, and composition. In this project, we develop an OWL-S ontology of tasks to be used for the semi-automatic generation of performance models. We discuss our experience with OWL-S/Protege as well as the reasoning capabilities that we add to monitor the consistency of the ontology and to support inferencing.
Professor Hoda S. Abdel-Aty-Zohdy with Linda Murphy (Graduate Student)
Abstract: Genetic algorithms (GA) are designed to search for, discover and emphasize good solutions by applying selection and crossover techniques, inspired by nature, to supply solutions to engineering systems. Genetic algorithms operate on pieces of information like nature does on genes in the course of evolution. All individuals of one generation are evaluated by a fitness function. This paper presents an approach to implement a genetic algorithm to depict a recently developed “Integrated Model” for defect tracking for product deployment in telecommunication systems by means of a solution space representing target variables. The genetic algorithm inputs these target values as dynamic input measurements. From these measurements, the best possible fused values are found for the target variables. The goal of the genetic algorithm is dynamically to update the parameters applied to the input measurements to find the optimum solution for the defect tracking model system. Focus will be given to one dimension of sensor input measurements consisting of three four-bit binary sensor inputs varying within a given range of data points. The genetic algorithm is applied to these inputs by means of a 64 6-bit random member binary population using the “Half-Sibling and a Clone” (HSAC) technique of crossover and mutation. The population members are evaluated using a fitness function where the fittest individuals are retained to survive and produce offspring for the next generation and the remainder are discarded. Genetic diversity is maintained through using a roulette wheel technique. The simulation tool MATLAB will be used to simulate the genetic algorithm. The genetic algorithm will be completed in VLSI using Verilog and the Mentor Graphics tools. The first stage components have been designed and completed using the Mentor Graphics toolset.
- An Operational Transconductance Amplifier in 0.18um Silicon-On-Insulator (SOI)
Professor Hoda S. Abdel-Aty-Zohdy with Dan O'Rourke (Graduate Student)
Abstract: An operational transconductance amplifier (OTA) using three cascaded comparator stages is presented in 180nm Fully Depleted Silicon On Insulator (FDSOI) technology processed at MIT Lincoln Laboratory. Each comparator stage used 14 transistors with close to minimum aspect ratios. The OTA is self-biasing without the need for external bias circuitry, and provides a rail to rail input common mode range. The use of deep submicron and FDSOI technology provides for an open loop gain of 64.5dB, unity gain bandwidth product of 2.27 GHz using an actual area of only 860 um^2.
- Bacteriorhodopsin (bR) Protein Diffusion Model for Biological Computation
Professor Hoda S. Abdel-Aty-Zohdy with Didimo Garcia Neto (U/G RA)
Abstract: A potential biological structure for computer volumetric memory is investigated. Bacteriorhodopsin is a protein found in the purple membrane of the bacteria Halobacterium salinarum. This protein has light absorption properties that generate different stable states allowing the use of multi-level logic as well as binary logic. Bacteriorhodopsin has a molecular volumetric size of 8x107nm3 which is expected to be used as a logical bit, as long as energy diffusion does not trigger molecules around the target molecule. CHARMmTM has been used to simulate the energy response of Bacteriorhodopsin at room temperature 300K for the bR ground and excited states. The K state takes place after an initial blue light (λ= 635nm) absorption on the bR state. The energy difference is found to be an increase of |ΔEbRàK| 1086.92 kcal/mol which is responsible for triggering the photocycle that also includes the states K, L, M, N, and O, and for changing the molecular conformation of each state. The energy difference beteen states bR and O have also been simulated and found to be equal to |ΔEOàbR| = 783.979 Kcal/mol matching previous experimental results. Therefore, conformational interference produced by the energy variation throughout all states will not produce photons necessary for the isomerization reaction on molecules around the target. Thus, a minimum volumetric bR memory bit could be as small as the molecular size of bR, if light projection equipments facilitate. Further Quantum Molecular (QM) analysis would provide an extended model for this macromolecular energy study, if needed.
- Dynamic Impedance Model of Graphite Piezo-ElectroChemical Transducer (PECT) Effect for a Smart Battery
Professor Hoda S. Abdel-Aty-Zohdy with Purvi Teli (MS Student), L. Vogel (Graphi Tech, Inc)
Abstract: Intelligent power management for dry cell batteries may be accomplished by external circuitry which is connected to the individual power cells. In comparison, the presented Graphite circuit model, along with lead-acid battery technology facilitates the power management of wet cells in sealed packaging. This paper reiterates the Piezo ElectroChemical Transducer (PECT) effect based on the intercalation of graphite with sulfuric acid; Introduces a first attempt at developing a dynamic circuit model which will facilitate for a wide range of smart PECT applications. The paper also addresses the usage of PECT effect device for smart battery management, which operates in sulfuric acid environment. The developed dynamic impedance circuit model of PECT effect device can be used further to understand the changes in resistance and reactance properties of PECT device with the change in the temperature, voltage, current, stages, type of graphite and the concentration of sulfuric acid of electrochemical intercalation of graphite with sulfuric acid.
- Wavelets as Basis in Recurrent Dynamic Neural Networks (RDNNs) for Telecommunication Applications
Professor Hoda S. Abdel-Aty-Zohdy with Hemal Shah (MS Graduate Student)
Abstract: This research explores the use of wavelet basis Recurrent Dynamic Neural Network (RDNN) to improve the estimation of reliability growth of communication network’s software. The presented RDNN handles noise contaminated data and provides enhanced speed and performance of the system as compared with alternate approaches. Non-linearity of the system is represented by proper selection of the wavelet function. The Integrated defect tracking model parameters and the data are fed to the RDNN and the network is trained for optimizing the defect tracking model performance. The designed system will assist the service release management in obtaining more effective risk reduction. Using wavelet basis for RDNN required only 10 iterations compared to 200 iterations with hump as basis function. It also reduces the maximum percentage error from 88% to 7.69% in the expected outputs. Thus wavelet-basis RDNN improves the telecommunication system defect tracking and network deployment.
Ka C. Cheok
Abstract: The objective is to develop autonomous motion planning techniques for Omni-Directional Vehicles (ODV). Available sensor technologies like UWB based ranging and positioning, MEMS based inertial sensors (gyro sensors and accelerometers), and miniature low-cost cameras provide information that will be processed in an intelligent autonomous navigation architecture. The architecture is JAUS compatible and includes obstacle avoidance and path planning. One of the goals is to use autonomous robotic systems as personal assistants in a wide variety of applications. A critical component in the project is accurate interpretation of user intent and minimization of operator workload in using the robotic systems. Technologies that will help achieve this objective are voice recognition, touch panels, force feedback etc.
Ka C. Cheok
Abstract: The objective of to develop a novel high-speed positioning and guidance technology using emerging UWB GHz ranging and communications technologies. One of the goals is to demonstrate autonomous robotic guidance and navigation technology at high speed (~35 mph) and high accuracy (<1”) for autonomous robotic mine detection vehicles by mid 2006. Other autonomous robotic applications for military include scouting, retrieval, follower vehicles, security guard vehicles, cave exploration and mapping, inspection systems, logistics and warehouse systems, aerial vehicle guided landing, etc.
Ka C. Cheok
Abstract: The objective is to develop a prototype Bio-Chemical Detection device that utilizes Quartz Crystal Microbalance (QCM) mass sensors. A high performance micro-controller technology, together with unique developments of the quartz crystal coating (e.g. ionic liquid, carbo-hydrates and recombinant antibody coating), provides a unique opportunity to develop a low-cost light-weight and real-time highly sensitive BWA detection system for a variety of targeted explosive, biological or chemical agents. The portable device can be employed by individual soldiers, semi-autonomous and autonomous robotic vehicles in multiple operational environments. Application examples are found at vehicle checkpoints, inside and outside security of various facilities, convoy routes, lakes and rivers, first responder scenarios, etc. The project also aims to detect explosives (like IED’s and land mines) and other non-BWA chemical analytes.
- An Automated Microbial Detection System for Monitoring Water Pollution
Devendra Bajpai and Manohar Das
Abstract: This research proposes a technique for recognition of the various micro biota found in waste water. High resolution video sequences of microscopic images are used to identify water borne micro biota and estimate their concentrations. The quantity of various micro biota at a given instant of time can be related to the quality of waste water.
- A Robust Method For Imperctible High-Capacity Information Hiding in Images
Johann Briffa and Manohar Das
Abstract: The goal of this research is to advance the state-of-the-art of high-capacity information hiding in images, with particular application to covert communication (steganography). This is achieved by developing novel channel models for image steganography, devising new methods for bandwidth-efficient signal embedding and extraction as well as error protection, while ensuring visual and statistical imperceptibility.
- An Optimal Energy Delivery Weld Controller
Gurunath Kedar-Dongarkar, Vernon Fernandez, and Manohar Das
Abstract: The objective of this research is to design a microprocessor based optimal energy deliver control (OEDC) system for the resistance spot welding process. It is expected to produce welds that are optimized and consistent during production, thus enabling a reduction of the body shop by at least 10 percent. The main advantages of OEDC include high nugget diameter to energy ratio for a given cap diameter and stack thickness, larger weld lobe, and adaptability to both AC and MFDC weld controllers.
Michael P. Polis, Irina Sivergina, and Ilya V. Kolmanovsky
Abstract: This research treats the problem of estimating the heat flux through the free end of a thermoelastic rod which is allowed to come into contact with a rigid obstacle. This problem is motivated by the need to develop techniques for indirect measurement of heating in applications such as brake systems and machine tools. Under a quasi-static approximation the problem becomes that of characterizing thermal processes in the rod. Assuming that direct and exact measurements at the contacting end of the rod cannot be taken, the problem is to determine if there is contact with the obstacle, and if there is contact, to characterize the conductivity processes at the contacting end. We study the case of weighted average temperature measurements throughout the rod. Identifiability results and on-line recursive estimation procedures are developed.
Abstract: The research is concerned with computer modeling of EMC measurements of automotive data CAN busses, operating at 500 KB/s, and computer modeling of GHZ frequency range emitted electromagnetic fields, which are generated by fast digital or analog communication devices. Computer modeling of the EMC tests can be very helpful in trainings and test preparation, and it can reduce time necessary to determine tested device electromagnetic field directivity, especially within GHz frequency ranges.
Mohamed A. Zohdy, S Alashhab, A Harb
Abstract: The research objective is to design novel signals to synchronize two chaotic nonlinear systems, a drive system and a response system for communication applications. A Recursive backstepping approach and a master-slave approach are utilized here. Preliminary symbolic and numerical results show good promise for nonperiodic and chaos signals synchronization in multivariable communication systems.
Barbara A Oakley, Darrin Hanna, Zenon Kuzmyn, Richard M Felder
Abstract: A year-long, four-semester survey was conducted of 2,186 engineering and computer science students involving the use of teamwork in their classes. Several factors were found to increase student satisfaction with their experience, including receiving guidance from the instructor about how to conduct teamwork and having the ability to keep uncooperative students from getting credit for assignments and to fire them as a last resort.
Barbara A. Oakley, Senior Member, IEEE, Darrin M. Hanna, Member, IEEE,
Abstract: This paper describes results involving the percentage cell lysis of SWLA-2 murine hybridomas produced by AC electric field pulses at 1kHz with pulse widths ranging from 1 ms to 1 second. Cells that had been exposed to the electric fields were cultured and replicate samples were examined at 48 hours to determine the number of viable cells.
Barbara Oakley, Doreen Lawrence, Jesse Petway,
Abstract: This paper provides an evaluation of the effects of using the “Kumon” method for supplementing the teaching of mathematics in the inner-urban school district of Pontiac, Michigan. Michigan Educational Assessment Program (MEAP) test scores are cited for Herrington, Owen, and Crofoot elementary schools, which used the Kumon program during part of their ninety minutes of daily mathematics instruction, and demographically matched Emerson Elementary School, which did not use the Kumon program during its ninety minutes of daily mathematics instruction. In 2003, Emerson had 4.5% of its students exceed Michigan standards. In 2004 that number was 8.6%. At Herrington Elementary School, however, the MEAP scores rose from 39.7% to 89.1% of students exceeding state standards during the same single year period. Crofoot went from 0.0% of students exceeding Michigan state standards in 2003, to a remarkable 58.1% exceeding standards in 2004. Owen also showed substantive improvements.
The research project, a joint effort between Oakland University’s School of Engineering and the School District of Pontiac, reveals that supplementation with the Kumon method as a partial replacement for a traditional mathematics program appears to result in significant improvements in statewide Michigan Educational Assessment Program test scores for mathematics. Boundary Heat Flux Estimation In Quasi-Static.
Chen Fu, Barbara Oakley, Senior Member, IEEE, Shudong Li, Wenlei Zhao
Abstract: Drug galvano-acupuncture is a new medical therapy that has been developed and refined over thirty-one years of research and clinical practice. It uses a combination of modern technology, traditional acupuncture, herbal medicine, and massage therapy techniques. The therapy works by inducing an electric field at the surface of the skin that allows various medications to penetrate the skin’s surface. The interacting combination of medication, along with electrical and mechanical stimulation, appears to quickly produce healing effects with no side effects. This method has been broadly used with what appear to be positive effects on a number of different conditions, including neuralgia and stroke.
Sankar Sengupta and Robert Van Til
Abstract: Our research concerns several areas from lean manufacturing, i.e., the Toyota Production System. Our focus is on the development of tools for identifying and removing waste, primarily inventory (Work-In-Progress or WIP) and over production. from a manufacturing system. We collaborate with Oakland University’s Pawley Institute on several research and educational projects concerning lean manufacturing.
- A New Database Paradigm
Abstract: The current database models were all defined in the years 1969 and 1970 when the processing capability of computers were drastically different than what is available today. With modern computing power, a new paradigm for the definition, storage, retrieval, and analysis of user data is possible. The new database model focuses on the use of metadata, that is, data about the data, to permit far more flexible and effective modeling of real world artifacts. This paper describes the nature of the new database paradigm and the advantages for which we all are waiting.
- Automatic Software Generation
Abstract: Software costs too much, takes too long to build, and doesn’t work when delivered. This paper describes precisely why this is true and shows a way out that builds better software, documentation, and training materials at a greatly reduced cost by automating the process of software development. While the methods cannot yet work for an arbitrary application, the methods can be easily extended to any domain with effort.
- Making Better Decisions Concerning Complex Systems
Abstract: The complexity of human-created systems has exceeded our ability to understand them. Hence, we find human, political, ecological and financial disasters aplenty. This paper describes a set of approaches to decision making in complex domains that permits a more complete analysis and better decisions. One specific approach to the development of new software systems is described in detail.
- Psychologically Based Natural Language Understanding
Abstract: A major reason that we do not have adequate computer understanding of written text is that we do not clearly understand how people understand written text. This paper describes a set of research activities over many years that have focused on the development of a system that can understand English. A new pattern recognition model based on human short term memory models is described in detail.
- The Department of Industrial and Systems Engineering
Abstract: Oakland University and its School of Engineering and Computer Science have launched a new department of Industrial and Systems Engineering. The various faculty members come together with a singular focus on the design, analysis, and modeling of complex systems from a variety of perspectives. This paper describes the research, teaching, and outreach components of the new department and invites participation in a university department that is doing things differently than most academic units.
- Radial-Ply Tire’s Three-Dimensional Transmissibility
View: Slides | Poster
Prof. Y. P. Chang , Weidong Zhang
Abstract: A full nonlinear finite element passenger car radial-ply tire model was developed and run at a constant speed of 50 km/h to investigate tire's transmissibility in x, y, and z directions. The tire model was constructed in extreme detail with three-dimensional solid, layered membrane, and beam finite elements. The reaction forces of the tire axle in longitudinal (X axis), lateral (Y axis), and vertical (Z axis) directions were recorded when the tire encountered a cleat, and then the FFT algorithm was applied to examine the transient response information in the frequency domain. The result showed that this passenger car tire has clear peaks of 42 HZ (lateral), 46 HZ and 92HZ (longitudinal), and 83HZ (vertical). An analytical rigid ring model was also formulated, based on the dynamic equations of rigid ring tire model, the characteristic equations were obtained and solved for eigenvalues and eigenvectors. By distinguishing the mode shapes, the frequencies were categorized into longitudinal, lateral, and vertical directions. These frequencies can also be used to predict the peak transmissibility in the corresponding direction. Both approaches results were validated against more than twenty previous studies by theoretical, numerical, or experimental approaches and showed good agreement.
- Velocity Based Multi-Body Approach for Vehicle dynamics
Prof. Y. P. Chang , Weidong Zhang
Abstract: An automobile is a complex close loop multi-body system, which includes the chassis, front suspension, rear suspension, wheels etc. In such a close loop topology, the chassis is modeled as a rigid body, which is linked to low arms, upper arms, tire rods, and tie bars in SLA suspensions by kinematics joints. The dampers and springs in suspensions are considered as velocity based and position based force elements separately. The magic formula is adopted to describe tire’s slip behavior. Based on the virtual power principle, the complete equations of motion including Langrage multipliers are formulated. This formulation is based on the velocity and acceleration vectors of the center of gravity and the angular velocity and acceleration vectors of each element. Velocity transformation is adopted to build the relationships between the dependent velocities the independent velocities, which consist of translational velocities at the center of gravity and angular velocities of the base body and at the kinematics joints. By using Runge-Kutta method, position variables for base body translation and rotation at kinematics joint can be directly acquired. Euler quaternion four parameters are solved from angular velocity and previous quaternion, and they are used to orientate the base body and spherical joints. In terms of these position variables, position and velocity of the rigid body are easily obtained recursively at a specific time. After a series of computations, the vehicle dynamic behavior time history is eventually reached. Velocity based multi-body approach highly increase computational efficiency, and provide an effective solver for vehicle dynamics and tire’s dynamics studies.
- Development and Numerical Simulation of Spot Welding Model
Laila Guessous, Sayed Nassar, Meir Shillor, and Suresh Putta
Abstract: The goal of this collaborative project is to develop and numerically simulate a model to describe the process of resistance spot welding (RSW). Of particular interest are the differences in weld nugget formation and quality when AC or DC power is applied. Of further future interest is the quantification of residual stresses in welded joints.
- Numerical Investigations of Pulsatile Flows
Laila Guessous and Suresh Putta
Abstract: The goal of this research is to develop a better understanding of the characteristics of pulsating flows and to investigate the effect of such pulsations on convective heat transfer. Such flows occur in internal combustion engines and exhaust systems, turbomachinery, biological flows, etc.
We are conducting Computational Fluid Dynamics (CFD) investigations of pulsating flows in a number of geometries (pipe and blunt flat plate). Pulsation is introduced by either oscillating the inlet pressure: P=Po(1+A cos wt) , or the free-stream velocity: U=Uo(1+A sin wt). Ultimately, we hope to gain insight into the physical mechanisms responsible for heat transfer enhancement or attenuation in the presence of a flow pulsation.
Abstract: A fundamental understanding of the transient characteristics and stability behavior of in-tube condensing flow systems is important in a broad spectrum of energy transport and conversion processes, ranging from reheat, reboiler, and submerged evaporator systems associated with nuclear and conventional power plants to applications in the process and chemical industries, as well as systems associated with refrigeration, air conditioning, and space power generation. In a tube-type condenser involving complete condensation, it has been seen that small changes in the inlet vapor flowrate momentarily cause large transient flow surges in the outlet liquid flowrate. Subcooled liquid inertia tends to increase these amplification characteristics and destabilize such systems. A one-dimensional, two-fluid, distributed parameter System Mean Void Fraction (SMVF) Model of the time-dependent distribution of liquid and vapor within the two-phase region is developed for predicting these transient- and frequency-response characteristics. The SMVF Model is seen to predict both the transient- and frequency-response characteristics quite well, including flow reversals, especially when consideration is given to the complex nature of the problem. The salient feature of the SMVF Model is its simplicity. Such simplicity, with an experimentally verified predictive capability, enhances the models' utility as both an educational as well as an analytical tool.
Abstract: One of the leading candidates for short, medium and possibly long-term replacement of fossil fuels for transportation usage is biodiesel. Because of increasing gas prices, and to a larger extent our increasing dependence on foreign sources of oil, an alternative is sought for purposes of national security without transition destabilization of our economy. As it is, biodiesel does not require modifications to current diesel engines to run, and there is no need for an infrastructure overhaul such as would be necessitated by migrating to a hydrogen economy. It is the transition between one fuel source and another that would have adverse economic consequences. The downside of biodiesel is mostlty in standardization of specifications (ASTM) and availability. As petroleum use increases each year (180 billions gallon used by US annually in the forms of gasoline and diesel fuel), we simply don’t grow enough biomass to keep up with current demand. Migrating to all diesel engines will increase efficiency by approximately 30 percent. Further, growing crops that yield high volumes of oil per acre will increase availability. The technology is mature and should be given a serious consideration in the social and political context of the
Zissimos P. Mourelatos, Jun Zhou
Abstract: Early in the engineering design cycle, it is difficult to quantify product reliability or compliance to performance targets due to insufficient data or information to model uncertainties. Probability theory can not be therefore, used. Design decisions are usually, based on fuzzy information that is vague, imprecise qualitative, linguistic or incomplete. Recently, possibility and evidence theories have been proposed to handle uncertainty with limited information as an alternative to probability theory. In this talk, the differences and application domains of Reliability-based, Possibility-based and Evidence-based design optimization methods will be highlighted. Subsequently, a computationally efficient design optimization method will be presented based on evidence theory, which can handle a mixture of epistemic and random uncertainties. The method quickly identifies the vicinity of the optimal point and all active constraints by moving a hyper-ellipse in the original design space, using a reliability-based design optimization (RBDO) algorithm. Subsequently, a derivative-free optimizer calculates the evidence-based optimum, considering only the identified active constraints. The computational cost is kept low by first moving to the vicinity of the optimum quickly and subsequently using local surrogate models of the active constraints only. Examples will illustrate the proposed methodology.
Zissimos P. Mourelatos, Hejie Lin
Abstract: Noise, vibration and harshness (NVH) is of increasing concern for the automotive and aerospace industries, due to the desire for new materials and lighter structures. This work describes an efficient and accurate methodology based on finite element analysis (FEA) and component mode synthesis (CMS). Because the computational cost is a major limiting factor for using FEA and CMS for large, complex structures, major improvements are made to CMS to achieve better efficiency. First, an interface reduction method is employed to obtain a more compact reduced-order model (ROM), so that further dynamic analysis such as forced vibration response, can be performed with better efficiency. A matrix-filtration method is also applied to improve the efficiency of both substructure analysis and interface reduction. In dynamic substructuring (or reduced-order modeling), it is commonly assumed that adjacent substructures have finite element meshes that match node-to-node at the interface. However due to distributed design and redesign, complex structures could very possibly end up with non-conforming (or mismatching) interfaces between different substructures. In this work, a method is also developed which handles non-conforming interfaces.
Zissimos P. Mourelatos, Daniel Wehrwein
Abstract: A vehicle drivetrain is designed to meet specific vehicle performance criteria which usually involve trade-offs among conflicting performance measures. A methodology is described for optimizing the drivetrain design including the axle ratio, transmission shift points and transmission shift ratios considering uncertainty. A complete vehicle dynamic model is developed using the bond graph method. The model includes the vehicle, engine, transmission, torque converter, driveline, and transmission controller. An equivalent MATLAB Simulink model is also developed in order to carry out the nonlinear dynamic analysis efficiently. A deterministic optimization is first performed to determine the optimum design in terms of fuel economy, without considering variations or uncertainties. Subsequently, a Reliability-Based Design Optimization is carried out to find the optimum design in the presence of uncertainty. The dynamic analysis and optimization is exclusively performed in the MATLAB environment. A vehicle example illustrates the design methodology in detail.
Zissimos P. Mourelatos, Jinghong Liang
Abstract: Mathematical optimization plays an important role in engineering design, leading to greatly improved performance. Deterministic optimization however, can lead to undesired choices because it neglects uncertainty. Reliability-based design optimization (RBDO) and robust design can improve optimization by considering uncertainty. We will describe an efficient design optimization method under uncertainty, which simultaneously considers reliability and robustness. A mean performance is traded-off against robustness for a given reliability level of all performance targets. This results in a probabilistic multi-objective optimization problem. Variation is expressed in terms of a percentile difference which is efficiently computed using the Advanced Mean Value (AMV) method. A preference aggregation method converts the multi-objective problem to a single-objective problem, which is then solved using an RBDO approach. Indifference points are used to select the best solution without calculating the entire Pareto frontier. Examples illustrate the concepts and demonstrate their applicability.
Zissimos P. Mourelatos, Prashant Patel, Paras Shah
Abstract: Engine NVH (Noise, Vibration, and Harshness) is an important design issue for I.C. engines since it plays a crucial role on how a customer perceives engine quality. There is an increasing urgency therefore, among engine manufacturers to design and produce low noise engines. It is well known that the piston assembly can be a major source of engine mechanical friction and cold start noise, if not designed properly. The piston secondary motion and piston-bore contact pattern determine the piston NVH characteristics because they affect the skirt-to-bore impact force and therefore, how the piston impact excitation energy is damped, transmitted and eventually radiated from the engine structure as noise. An analytical method is presented for simulating piston secondary dynamics and piston-bore contact for an asymmetric half piston model. The method includes several important physical attributes such as bore distortion due to thermal expansion, bolt loading and cylinder pressure, inertia loading, piston flexibility and skirt-to-bore clearance.
Dr. Sayed A. Nassar, Vinayshankar L. Virupaksha
Abstract: In this paper a three dimensional mathematical model is derived to study the thermomechanically induced interfacial stresses in adhesive bonding of composite materials. The influence of bonding agents, material properties and thickness on the interfacial stresses is also investigated. The model is based on the continuum mixture theories of wave propagation. The mechanical and thermal loads are varied along with the bonding material properties and thickness to optimize the interfacial shear stresses.
- Effect Of Tightening Speed On The Torque - Tension And Wear Pattern In Threadded Fasteners
Dr. Sayed A. Nassar, Saravanan Ganeshmurthy
Abstract: This experimental study investigates the effect of tightening speed and coating on both the torque tension relationship and wear pattern in threaded fastener applications. The fastener torque tension relationship is highly sensitive to normal variations in the coefficients of friction between threads and between the turning head and the surface of the joint. Hence, the initial level of the joint clamp load and the overall integrity and reliability of a bolted assembly is significantly influenced by the friction coefficients. The effect of repeated tightening and loosening is also investigated using M12, Class 8.8, fasteners with and without zinc coating. The torque tension relationship is examined in terms of the non-dimensional nut factor K. The wear pattern is examined by monitoring the changes in surface roughness using a WYKO optical profiler and by using a LECO optical microscope. A Hitachi S-3200N Scanning Electron Microscope (SEM) is used to examine the contact surfaces, under the fastener head, after each tightening/loosening cycle. Experimental data on the effect of variables and the tightening speed, fastener coating and repeated tightening on the nut factor are presented and analyzed for M8 and M12, class 8.8, fasteners.
- Effect of Bolt Tightness on the Behavior of Composite Bolted Joints
Dr. Sayed A. Nassar, Vinayshankar L. Virupaksha
Abstract: This study provides an experimental and analytical investigation of the behavior of a double bolted single lap shear composite joint. Various scenarios of bolt tightness are considered for composite-to-composite and composite-to-aluminum bolted joints. Progressive damage analysis is provided for the composite coupons in two regions; namely, the surface under bolt heads and near the contact with the shank of the bolt; the damage analysis is performed using an optical microscope. Four tightening configurations are used in the testing of each double bolted joint. These configurations permit each of the two bolts to be either tight or loose. The analytical part of the study utilizes a 3-D finite element model that simulates the bolt tightness and the multilayered composite coupons. The experimental and finite element results are correlated.
- Elastic Interaction And Gasket Creep Relaxation In Gasket Joints
Dr. Sayed A. Nassar and Ali A. Alkelani
Abstract: An experimental study is presented in order to determine the clamp load loss due to elastic interaction and gasket creep relaxation in bolted joints. Studied parameters include the gasket material and thickness, bolt spacing, tightening sequence, fastener grip length, and level of the fastener preload. The joint is composed of two steel flanges and a gasket made of Styrene Butadiene Rubber or Flexible Graphite. The flanges are fastened together using M12x1.75 Class 10.9 fasteners. Force washers are used to monitor bolt tensions in real time.
Four different gasket thicknesses of Styrene Butadiene Rubber (1/16, 1/8, 3/16, and 1/4) and two thicknesses of Flexible Graphite (1/16 and 1/8) are considered. For the same bolt circle of the flange, the bolt spacing is varied by using a different number of bolts; spacing that corresponds to using three, five, or seven bolts is considered in this study. The effect of the tightening strategy is studied by using sequential, star, or simultaneous tightening patterns. Bolt tightening is accomplished by using either an electric digital torque wrench with various control options, or by using a production-size multiple spindle fastening system that is capable of simultaneous tightening of all fasteners. Experimental data is presented and analyzed, in order to study the effect of the various parameters on the clamp load loss due to the combined effect of elastic interaction and gasket creep relaxation at room temperature.
- Interfacial shear stresses between fuel cell materials
Dr. Sayed A. Nassar, Xianjie Yang and Basil A. Housari
Abstract: Static analysis was conducted out in order to estimate the influence of bonds on the interfacial shear stresses in laminated fuel cell under mechanical, humility and thermal loadings. The analytical formulae of the interfacial stresses were derived.
- Mechanical Fastening and Adhesive Bonding of Composite Materials
Dr. Sayed A. Nassar and Vinayshankar L. Virupaksha
Abstract: This research is to investigate the issues in fastening and joining technology for advanced composite used in aerospace and automotive industry
- Optical Monitoring And Control Of Bolt Tightening
Dr. Sayed A. Nassar, Aidong Meng
Abstract: An optical method is presented for the real- time monitoring of the bolt tightening process that provides the necessary clamping force in bolted assemblies. The method uses 3-D Electronic Speckle Pattern Interferometry (ESPI) technique to measure and monitor the joint deformation and strain fields in the joint around the tightened fastener, and to establish a reliable correlation with the clamp load provided by the fastener tightening. Because the relationship between the clamp load and joint deformation is independent of the frictional variables of the fastener, the direct monitoring of the deformation and strain fields in the clamped joint would provide a more reliable measure of the clamp load level, as compared to the conventional reliance on the tightening torque to predict the resulting clamp load level. The validity of the optical technique is also ascertained by comparing the results to that obtained by using finite element analysis and other classical mechanics of materials methods.
- Self-Loosening Of Threaded Fasteners Due To Cyclic Transverse Loads
Dr. Sayed Nassar and Basil Housari
Abstract: A mathematical model and an experimental procedure are presented to study the self-loosening phenomenon of threaded fasteners that are subjected to cyclic transverse loads. The study investigates the effect of thread pitch, initial bolt tension, the amplitude of the external excitation, and some other factors on the loosening of a single-bolt joint. The rate of drop in the joint clamp load (fastener tension) per cycle, as well as the total number of cycles that would cause the complete loss of clamp load, are monitored.
In the mathematical model, the differential equations of linear and angular motion of the bolt are formulated in terms of the system properties and the external cyclic transverse excitation. Numerical integration of the equation of angular motion provides the bolt rotation in the loosening direction, which causes the partial or full loss of the clamp load. An iterative MATLAB code is developed and used for the calculation of tension loss in the fastener tension due to the self-loosening. Analytical and experimental results are discussed.
- Clean Diesel Technology: HAT- Hydraulically Actuated Turbine
Objective: To develop an efficient, hydraulically-actuated turbine to minimize “turbo lag” in modern, high-speed turbocharged diesel engines.
Motivation: Modern diesel engines offer the potential for about a 20% increase in fuel efficiency over their gasoline counterparts. Acceptance into the U.S. marketplace for light duty diesel engines will depend upon successes in reducing particulate and NOx emissions.
Particulates (soot) are formed in fuel-rich regions, especially during transient operation during which the air flow lags the increase in fuel flow. One method proposed for minimizing the lag in air flow is to hydraulically accelerate the turbocharger
- Heat Transfer in the Exhaust Manifold of a Spark Ignition Engine
Objective: To develop a better understanding of the heat transfer characteristics in the exhaust manifold and to propose analytical correlations for the convective heat transfer coefficient.
- Measuring Gas Temperature in Hot Pulsating Flows
Objective: To investigate the use of fine wire thermocouples in hot pulsating gas streams to determine instantaneous gas temperature.
Motivation: When a thermocouple is used in a transient gas flow, the thermocouple temperature differs from the instantaneous gas temperature due to the “thermal capacitance” of the thermocouple junction, and also due to conduction effects and radiation to/from surroundings. These undesirable effects are directly dependant upon junction size and wire diameter. In a flow like that found in an engine exhaust manifold, the thermocouple must be made very small to minimize these effects, but must also be robust enough to survive the forces imposed by the pulsating gas. The problem remains of how to use practical thermocouple measurements to determine the instantaneous gas temperature.
• Validate 1-D simulation of exhaust flow using experimental measurements
Xia Wang and Ismat A. Abusi
Abstract: A fuel cell research is just initiated on
Another focus of research is to manufacture new bipolar plate. The proposed study will initially concentrate on development of composites made of conductive woven graphite or metallic fabrics and conductive elastomers. Samples will be initially fabricated by compression molding. Performance characteristics including mechanical, electrical, thermal properties will be evaluated, along with durability of the composites in a fuel cell environment. Most importantly, with the model developed in this proposal, the flow structure across the bipolar plate will be simulated by FEMLAB software, which is meant to guide the optimal design of channel on the bipolar plate.
Abstract: A similarity analysis has been developed for a two dimensional forced convection turbulent boundary layer with and without pressure gradient. Two new inner and outer temperature scalings are derived by means of similarity analysis of the equations of motion. The new scalings will be verified by the experimental data withadverse pressure gradient (APG), favorable pressure gradient (FPG) and zero pressure gradient (ZPG), respectively. It will be shown that the mean temperature profiles are dependent on the external pressure gradient and the upstream conditions. However, using the new scaling in inner variables or in outer variables, the temperature profiles collapse into a single curve. Thus, the true asymptotic solution for the temperature field exists even at a finite Peclet number. These results are confirmed by using the existing experimental data and compared with the results from various scalings.
Abstract: By applying the theory of similarity analysis to the RANS boundary layer equations, it will be shown that the outer part of an adverse pressure gradient turbulent boundary
layer tends to remain in equilibrium similarity, even near and past separation. Such boundary layers are characterized by a single and constant pressure gradient parameter and its value appears to be the same for all adverse pressure gradient flows, including those with eventual separation. Using this and the integral momentum boundary layer equation, it is possible to show that the shape factor at separation also has to within the experimental uncertainty a single value of 2.76. These results are consistent with the experimental results, and are value for the boundary layer separation control.
- 3D Digitization and Application
Dr.Lianxiang Yang, Sheng Liu and Praveen R Samala
Abstract: Digital 3D profilometry is a non-contact, full-field and fast method for 3D profile digitization. It has relatively simple setup with a very high precision and measurement accuracy. Recently the use of Digital 3D Profilometry in the automotive industries has become increasingly widespread. The effective techniques for 3D profile measurement, especially surface flatness measurement, have become more and more significant. Different optical inspective methods such as 3D profilometry, laser scanning and CMM have been applied for surface flatness measurement. Among these methods, 3D profilometry seems to be the fastest and inexpensive method with quite precise result. Surface flatness plays an important role in many circumstances, such as sealing and contacting. Using digital 3D profilometry to measure surface flatness is a new challenge to researchers. In this project, new development method is presented to measure surface flatness precisely. Also the principles and procedures employed are discussed in detail. Measurement applications show a very potential future for digital 3D profilometry technique in surface flatness measurement.
- DSPI for Strain/Stress Measurement, Vibration Analysis and Quality Inspection
Dr.Lianxiang Yang, Praveen R Samala and Sheng Liu
Abstract: Holographic interferometry is a well-established method for measuring 3D-deformations and thus 3D-strains. ESPI can be considered an electronic version of holographic interferometry that uses a CCD camera instead of photographic film to acquire electronic fringe images. First, a laser is split into two illuminating beams (an object beam and a reference beam). The reflecting beam from the surface of the sample is combined with the reference beam, which results in an interference pattern named as a speckle interferogram. The phase difference between the object beam and the reference beam is indirectly recorded through intensity of the speckle interferogram. Residual stresses exist in all materials without the application of any external loads or temperature change. They are introduced into the materials either during the manufacturing or fabrication processes. The nature, distribution and prediction of these stresses within in a metal is a complex and not completely understood phenomenon. Accurate and precise measurement of these stresses is important for fatigue analysis and design of various automotive processes. The purpose of this project is to demonstrate the application of DSPI technique combined with hole drilling process for a whole field strain measurement with automated data analysis. Using this technique we are able to measure both the in plane and out-of-plane stresses.
- NDT/NDE by Digital Shearography
Dr. Lianxiang Yang, Praveen R Samala and Sheng Liu
Abstract: Digital Shearograhy has demonstrated great potential in revealing defects in objects, especially in detecting delaminations in composite materials, honeycomb structures. It is gaining more and more acceptance by automotive and aerospace industries in the field of nondestructive testing (NDT). A key optical component used in shearography is a shearing device in which the shearing amount, shearing direction and under the most cases the phase shift technique are determined and introduced. This project presents a method to measure residual strain by digital shearography while BETABRACE reinforcement is adhered to sheet steel along the temperature profile during cure, determining critical properties, such as the temperature during which residual strain is initiated and the magnitude of this residual strain.
- Non-Destructive Evaluation of Spot Weld using Digital Shearography
Dr.Lianxiang Yang, Praveen R Samala and Sheng Liu
Abstract: Spot Welding is now widely used in the fabrication of sheet metals, mainly due to the cost and time considerations. Spot welds are found in nearly all products where sheet metal is joined. Examples range from a single metal toolbox to nearly 10,000 spot welds found in a typical passenger car. Obviously the quality of the spot weld has a direct impact on the quality of the product. The problem of estimating the spot-weld quality is an important component in quality control. If the weld nuggets are improperly or incompletely formed, or the area surrounding the nugget is smaller than required, the structural integrity of the entire part may be uncertain. Furthermore these inconsistencies are usually internal and are seldom visible to Optical Inspection. This study is focused on the non-destructive evaluation of the spot welds using ‘Digital Shearography’. The project mainly focuses on the implementation of this technique for the evaluation of the size of spot-welds, accurately and inline to the production facility. This study helps us in providing a better quality and safety product. Since it is a laser interferometric technique we have a very high measuring sensitivity and a deformation of about 100nm(about 4 millionth inch) can be measured.
- Effect of surface treatment on torque-tension relationship in Threaded Fasteners
Qian (Beth) Zou, Sayed Nassar, Tianshu Sun
Abstract: An experimental study is presented in order to investigate the effect of surface roughness, coating, and lubricants on the torque-tension relationship in bolted assemblies. Three levels of surface roughness, three types of surface coating, and three different lubricants are considered fro the fastener underhead and the joint surface; namely, low, medium, and high levels of surface roughness; low, medium, and high friction surface coating; solid lubricant, grease, and oil lubricant. In this study, the torque-tension data is expressed in terms of the value of the nut factor as well as its scatter. The safety and reliability of bolted assemblies are mainly determined by the level and the stability of the clamp load provided by the initial tightening of the threaded fastener. The value of initial clamp load, which is achieved by a specific level of tightening torque, is highly sensitive to the friction torque components. This study provides an insight into the reliability of the existing engineering practices for estimating the clamp load level from the tightening torque. Hence, the findings of the study would help enhance the reliability and the safety of bolted assemblies, especially in critical applications.
- Wear Model for Piston Ring and Cylinder Bore System
Qian(Beth) Zou, Yunchao Qiu
Abstract: A new wear model for piston ring and cylinder bore system has been developed to predict wear process with high accuracy and efficiency. It will save time and cost compared with experimental investigations. Surfaces of ring and bore were divided into small domains and assigned to corresponding elements in two-dimensional matrix. Fast Fourier Transform (FFT) and Conjugate Gradient Method (CGM) were applied to obtain pressure distribution on the computing domain. By changing the wear coefficients of the ring and bore with accumulated cycles, wear was calculated point by point in the matrix. Ring and bore surface profiles were modified when wear occurred. The results coincided well with the general tendency of wear in a ring and bore system.