Ann Arbor, MI, United States

University of Michigan
Ann Arbor, MI, United States

The University of Michigan , frequently referred to as simply Michigan, is a public research university located in Ann Arbor, Michigan, United States. Founded in 1817 in Detroit as the Catholepistemiad, or University of Michigania 20 years before the Michigan Territory officially became a state, the University of Michigan is the state's oldest university. The university moved to Ann Arbor in 1837 onto 40 acres of what is now known as Central Campus. Since its establishment in Ann Arbor, the university campus has expanded to include more than 584 major buildings with a combined area of more than 34 million gross square feet , and has two satellite campuses located in Flint and Dearborn. The University was one of the founding members of the Association of American Universities.Considered one of the foremost research universities in the United States, the university has very high research activity and its comprehensive graduate program offers doctoral degrees in the humanities, social science, and STEM fields as well as professional degrees in medicine, law, pharmacy, nursing, social work and dentistry. Michigan's body of living alumni comprises more than 500,000. Besides academic life, Michigan's athletic teams compete in Division I of the NCAA and are collectively known as the Wolverines. They are members of the Big Ten Conference. Wikipedia.

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Zerehsaz Y.,University of Michigan | Jin J.J.,University of Michigan | Ebert S.M.,University of Michigan | Reed M.P.,University of Michigan
International Journal of Industrial Ergonomics | Year: 2017

In this paper, a statistical model is developed to predict the driver eye locations in military ground vehicles. The data were taken from a study on soldier driving postures and seating positions. The distribution of eye locations is represented by an “eyellipse”, a geometric construction that approximates the distribution of the eye locations using an ellipse. Eyellipses have been widely used for the design of passenger cars and commercial trucks. The location and dimensions of the soldier eyellipse were developed based on the data from 145 male and female soldiers who selected their preferred driving postures in a range of vehicle layouts presented in a vehicle mockup. Driver eye locations were modeled using regression analysis. The model predicts the distribution of eye locations as a function of vehicle interior layout for a soldier population defined by the gender ratio (fraction male) and the distribution of body dimensions within each gender. This is the first eyellipse model taking into account the effects of protective equipment and body-borne gear. The model has broad applicability to the design of tactical, truck-like vehicles with fixed accelerator heel points. © 2017 Elsevier B.V.

Document Keywords (matching the query): automobile bodies, automobiles, regression analysis.

Wu X.,University of Michigan | Wei Z.,Tenneco | Kang H.,University of Michigan | Khosrovaneh A.,General Motors
SAE Technical Papers | Year: 2017

Over the decades, several attempts have been made to develop new fatigue analysis methods for welded joints since most of the incidents in automotive structures are joints related. Therefore, a reliable and effective fatigue damage parameter is needed to properly predict the failure location and fatigue life of these welded structures to reduce the hardware testing, time, and the associated cost. The nodal force-based structural stress approach is becoming widely used in fatigue life assessment of welded structures. In this paper, a new nodal force-based structural stress recovery procedure is proposed that uses the least squares method to linearly smooth the stresses in elements along the weld line. Weight function is introduced to give flexibility in choosing different weighting schemes between elements. Two typical weighting schemes are discussed and compared. Published fatigue data of Gas Metal Arc Welds (GMAW) are utilized to investigate the mesh-insensitivity by comparing the structural stress results obtained from various mesh densities and patterns. The fatigue life correlation for GMAW coupons between the new structural stress and the experimental fatigue life data are discussed. Copyright © 2017 SAE International.

Jakubczyk A.,Medical University of Warsaw | Klimkiewicz A.,University of Michigan | Wnorowska A.,Medical University of Warsaw | Mika K.,Medical University of Warsaw | And 7 more authors.
Accident Analysis and Prevention | Year: 2013

Impulsivity and alcohol drinking are both considered as important predictors of unintentional as well as intentional injuries. However, relationships of impulsivity with risky behaviors and a history of accidents have not been investigated in alcohol dependence. The aim of this study was to analyze relationships between the frequency of risky behaviors and level of behavioral as well as cognitive impulsivity in alcohol-dependent patients. By means of Barratt's Impulsiveness Scale (BIS) and stop-signal task, the levels of cognitive and behavioral impulsivity among 304 alcohol-dependent patients were measured. Also, patients were asked to answer questions from the Short Inventory of Problems applying to risky behaviors and accidents after alcohol drinking. In addition participants completed a questionnaire to assess frequency of other behaviors from the analyzed spectrum (use of other drugs, driving or aggressive behavior after alcohol drinking). The statistical analysis revealed a significant association between impulsivity and frequency of risky behaviors in alcohol-dependent patients. Individuals with higher scores in BIS behaved more frequently in a risky way and had significantly more accidents after alcohol drinking. The association with risky behaviors was strongest for non-planning and attentional impulsivity subscales, whereas frequency of accidents was particularly associated with motor impulsivity. A multivariate analysis revealed that impulsivity was the most important predictor of risky behaviors, but did not significantly predict a history of accidents. Our study confirms that impulsivity is an important correlate of risky behaviors in alcohol-dependent individuals, along with global psychopathology and severity of alcohol dependence. © 2012 Published by Elsevier B.V. All rights reserved.

Document Keywords (matching the query): car driving, multivariate analysis, automobile driving, multi variate analysis.

Vozar S.,University of Michigan | Tilbury D.M.,University of Michigan
IFAC Proceedings Volumes (IFAC-PapersOnline) | Year: 2014

The results from a user study on teleoperated steering tasks are used to create a driver model under different latency conditions. The 31-subject user study explored the effects of latency on teleoperated steering tasks using a simulated mobile robot receiving input commands from a teleoperator via a computer gamepad. Using fundamental concepts from automotive steering models, and examining the users' input commands to the simulated robot under different latency conditions, a model of a human teleoperator for steering tasks was developed, tuned and validated. The model is a PD controller with feedback based on the projected lateral displacement of the robot. The tuning of the model gains for different latency scenarios reflects the real-world control strategies that users must employ when adapting to system latency. Simulation results show that the control gains can be interpolated to predict teleoperator performance under latency scenarios that were not tested with users. An analysis of the closed-loop stability of the system confirms our empirical observation that the ratio of the controller gains Kd/Kp increases as the latency increases. © IFAC.

Hu J.,University of Michigan | Klinich K.D.,University of Michigan | Reed M.P.,University of Michigan | Kokkolaras M.,University of Michigan | Rupp J.D.,University of Michigan
Medical Engineering and Physics | Year: 2012

In motor-vehicle crashes, young school-aged children restrained by vehicle seat belt systems often suffer from abdominal injuries due to submarining. However, the current anthropomorphic test device, so-called "crash dummy", is not adequate for proper simulation of submarining. In this study, a modified Hybrid-III six-year-old dummy model capable of simulating and predicting submarining was developed using MADYMO (TNO Automotive Safety Solutions). The model incorporated improved pelvis and abdomen geometry and properties previously tested in a modified physical dummy. The model was calibrated and validated against four sled tests under two test conditions with and without submarining using a multi-objective optimization method. A sensitivity analysis using this validated child dummy model showed that dummy knee excursion, torso rotation angle, and the difference between head and knee excursions were good predictors for submarining status. It was also shown that restraint system design variables, such as lap belt angle, D-ring height, and seat coefficient of friction (COF), may have opposite effects on head and abdomen injury risks; therefore child dummies and dummy models capable of simulating submarining are crucial for future restraint system design optimization for young school-aged children. © 2011 IPEM.

Document Keywords (matching the query): systems analysis, sensitivity analysis.

Lee T.-K.,University of Michigan | Filipi Z.S.,University of Michigan
International Journal of Automotive Technology | Year: 2011

Fast and predictive simulation tools are prerequisites for pursuing simulation based engine control development. A particularly attractive tradeoff between speed and fidelity is achieved with a co-simulation approach that marries a commercial gas dynamic code WAVE™ with an in-house quasi-dimensional combustion model. Gas dynamics are critical for predicting the effect of wave action in intake and exhaust systems, while the quasi-D turbulent flame entrainment model provides sensitivity to variations of composition and turbulence in the cylinder. This paper proposes a calibration procedure for such a tool that maximizes its range of validity and therefore achieves a fully predictive combustion model for the analysis of a high degree of freedom (HDOF) engines. Inclusion of a charge motion control device in the intake runner presented a particular challenge, since anything altering the flow upstream of the intake valve remains "invisible" to the zero-D turbulence model applied to the cylinder control volume. The solution is based on the use of turbulence multiplier and scheduling of its value. Consequently, proposed calibration procedure considers two scalar variables (dissipation constant Cβ and turbulence multiplier CM), and the refinements of flame front area maps to capture details of the spark-plug design, i. e. the actual distance between the spark and the surface of the cylinder head. The procedure is demonstrated using an SI engine system with dual-independent cam phasing and charge motion control valves (CMCV) in the intake runner. A limited number of iterations led to convergence, thanks to a small number of adjustable constants. After calibrating constants at the reference operating point, the predictions are validated for a range of engine speeds, loads and residual fractions. © 2011 The Korean Society of Automotive Engineers and Springer-Verlag Berlin Heidelberg.

Document Keywords (matching the query): sensitivity analysis, predictive simulations.

Sarkar S.,Clemson University | Chamberlain J.F.,Clemson University | Miller S.A.,University of Michigan
Journal of Industrial Ecology | Year: 2011

Summary: The disposal of scrap tires is one of the biggest solid waste issues facing some small island developing states (SIDS) in the Caribbean. Dominica is a small Caribbean island nation that seeks to maintain its well-founded image as the "Nature Island of the Caribbean." The economy has seen a steadily increasing import of both tires and cars, with no mechanism for exportation of spent tires. This study used data gathered from both government and international sources to estimate the quantity of tires currently on the island and projected each year up to 2020 to determine potential reuse options. We performed a material flow analysis (MFA) using tire import, vehicle registration records, and projected per capita income to determine the expected accumulation of waste tires. Vehicle registration is expected to rise with the island's wealth, which will affect the annual flow of tires. Two methods were used to predict vehicle growth over time. Our analysis showed an average waste tire output from the economy of 47,000 to 50,000 passenger tire equivalents (PTEs) per year, or approximately 470 to 500 short tons per year of mass. Such an output does not justify large expenditures of tire shredding and processing equipment, but whole tire applications may be feasible as potential disposition options. The methods can be easily replicated to give low-range and high-range estimates of waste tires disposed in the environment. © 2011 by Yale University.

Document Keywords (matching the query): caribbean, material flow analysis, automobile, automobiles, material flow analysis mfa, caribbean islands.

Ng J.C.,University of Michigan | Luckey S.G.,Ford Motor Company | Kridli G.T.,University of Michigan | Friedman P.A.,Ford Motor Company
Journal of Materials Processing Technology | Year: 2011

The automotive industry has recently begun using the superplastic forming (SPF) process to fabricate complex aluminum and magnesium alloy panels that cannot be formed at room temperature due to insufficient formability. One of the manufacturing problems encountered during SPF is excessive thinning in the form of a localized neck; which can lead to fracture. Localized necking can be predicted with the use of continuum elements in finite element analysis (FEA); however, the use of these elements in simulating SPF of large automotive panels is computationally intensive and often computationally prohibitive due to convergence issues. This paper examines the use of a modified material model (developed by engineers at Livermore Software Technology Corporation (LSTC) that can be used with conventional Belytschko-Tsay shell elements. This model considers normal stresses during SPF, which is needed to predict necking locations. The paper reports the results on investigating means for improving computational efficiency with this new formulation (i.e. element size, mass scaling, and adaptive meshing) and compares the performance of the normal stress element formulation with that of Belytschko-Tsay shell element in simulating the SPF process. The findings indicate that the newly developed formulation can be used for predicting localized thinning under SPF conditions. © 2011 Elsevier B.V. All rights reserved.

Document Keywords (matching the query): automotive industry, automotive panel, predictive accuracy, finite element analysis.

Northrop W.F.,University of Michigan | Bohac S.V.,University of Michigan | Chin J.-Y.,University of Michigan | Assanis D.N.,University of Michigan
Journal of Engineering for Gas Turbines and Power | Year: 2011

Partially premixed low temperature combustion (LTC) is an established advanced engine strategy that enables the simultaneous reduction of soot and NOx emissions in diesel engines. Measuring extremely low levels of soot emissions achievable with LTC modes using a filter smoke meter requires large sample volumes and repeated measurements to achieve the desired data precision and accuracy. Even taking such measures, doubt exists as to whether filter smoke number (FSN) accurately represents the actual smoke emissions emitted from such low soot conditions. The use of alternative fuels such as biodiesel also compounds efforts to accurately report soot emissions since the reflectivity of high levels of organic matter found on the particulate matter collected may result in erroneous readings from the optical detector. Using FSN, it is desired to report mass emissions of soot using empirical correlations derived for use with petroleum diesel fuels and conventional modes of combustion. The work presented in this paper compares the experimental results of well known formulas for calculating the mass of soot using FSN and the elemental carbon mass using thermal optical analysis (TOA) over a range of operating conditions and fuels from a four-cylinder direct-injection passenger car diesel engine. The data show that the mass of soot emitted by the engine can be accurately predicted with the smoke meter method utilizing a 3000 ml sample volume over a range of FSN from 0.02 to 1.5. Soot mass exhaust concentration calculated from FSN using the best of the literature expressions and that from TOA taken over all conditions correlated linearly with a slope of 0.99 and R2 value of 0.94. A primary implication of the work is that the level of confidence in reporting the soot mass based on FSN for low soot formation regimes such as LTC is improved for both petroleum diesel and biodiesel fuels. © 2011 American Society of Mechanical Engineers.

Document Keywords (matching the query): automobiles, thermal optical analysis, elemental carbon.

Agency: NSF | Branch: Standard Grant | Program: | Phase: Dynamics, Control and System D | Award Amount: 325.00K | Year: 2016

This research project will create new, rigorously grounded, methods for computationally efficient model predictive control. Model predictive control is based on computing system control inputs in response to sensor measurements through the use of real-time numerical optimization. It has proved invaluable in many important applications, including in the aerospace and automotive industries. Computational challenges stem from the need to optimize in real-time the response of large systems of constrained nonlinear dynamic equations in the presence of modeling errors and unpredictable disturbances. There are major difficulties in applying model predictive control to complex engineering systems, particularly when on-board computing power is limited. The most effective ways to address these challenges exploit problem-specific structure, in contrast to a one size fits all strategy. This project will produce classes of computationally efficient solution methods that can be appropriately tailored to specific problem characteristics. The developed theory and methods will be applied to control problems for automotive engines and aircraft propulsion systems, to address stringent performance requirements, growing system complexity, and numerous constraints. The implications for spacecraft orbital control will also be pursued to enable model predictive control solutions which expand spacecraft autonomy and resiliency. Project personnel will build on illustrations from automobile and aircraft engines and spacecraft missions to amplify STEM outreach efforts to local high school students from underrepresented groups.

The aim of this research project is to develop advanced methods for reducing the computational cost of solving nonlinear model predictive control problems, while maintaining acceptable accuracy. Both a theoretical justification of these methods and their efficient algorithmic implementation will be pursued. Inexact sequential quadratic programming-type methods for solving variational inequalities/inclusions associated with appropriate necessary conditions for optimality will be developed. Some of these methods will compute derivatives just at the starting point or at some selected iterations, while others will utilize inexact Newton iterations. The interplay between cost functions, constraints, closed-loop stability and performance will be studied in the context of these kind of implementations. In addition, novel computational and constraint handling strategies will be developed based on the analysis of Lipschitz stability and sensitivity of nonlinear model predictive control problems considered. Theoretically justified approaches to both offline and online constraint transformations will also be developed as another general pathway to obtain computational simplifications based on sensitivity analysis. Homotopy procedures supplied with error analysis will be applied to achieve efficient computation of model predictive control solutions.

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