Search Results (1 - 25 of 620 Results)

Sort By  
Sort Dir
 
Results per page  

Chen, ZhiliTowards real-time simulation of interactions among solids and fluids
Doctor of Philosophy, The Ohio State University, 2015, Computer Science and Engineering
The interactions among fluids and solids create many interesting phenomena that are excessively complex for manual creation in animation. It is popular to model these interactions in physically based simulation but it is challenging especially in real-time applications. Collisions handling is a major bottleneck for solid-solid interaction problems because of high computational cost of neighbor searching in space. Solid-fluid interactions are also difficult to simulate mostly because of the difference in representations of fluids and solids. Typically simulation systems use Eulerian methods for fluids and Lagrangian methods for solids. The most adopted coupling strategy uses solid velocity as boundary condition in fluid solver and integrate fluid pressure along solid boundary to apply force on solid. However, the quality of fluid animation is limited by resolution of Eulerian grid thus it cannot handle interaction with thin features on solids. In this dissertation we focus on specific types of interactions among fluids and solids and develop simulation methods with improved quality and performance toward real-time applications. First we address the problem of cloth, air, and deformable body interactions modeling in a layered structure as commonly seen in real world. We develop an accelerated collision detection method taking advantage of the layer structure to improve efficiency and an accurate anisotropic friction model to achieve fine contact details. The interaction of air and other layers is modeled using a fast air mass field model. Next, we turn to fracture simulation in solid-solid interaction, which is known to be computationally expensive in high resolution. We develop a surface refinement approach that adds fine details to existing low-resolution fracture animation with negligible extra computation cost. Finally, we explore coupling of fluid and solid with thin features. We take a stable and fast approach that couples hybrid Eulerian-Lagrangian fluid and position based solids. The approach shows its effectiveness in modeling the paint-brush interactions in a real-time oil-painting simulation system.

Committee:

Huamin Wang (Advisor); Roger Crawfis (Committee Member); Shen Han-wei (Committee Member)

Subjects:

Computer Science

Keywords:

computer graphics;computer animation;simulation;physics based simulation;fracture simulation;fluid simulation;CUDA;GPU;real-time graphics

LI, ZHENLONGDYNAMICS OF POLYMER SELF-ASSEMBLY BY COMPUTER SIMULATION
Doctor of Philosophy, Case Western Reserve University, 2011, Macromolecular Science and Engineering

We studied the self-assembly dynamics of two polymeric systems, block copolymer micelles and supramolecular polymer solutions using computer simulation.

Dissipative Particle Dynamics simulations were applied to study the equilibrium properties, kinetics of micellization and equilibrium chain-exchange in A2B3 and A4Bx(x=4,6,8) diblock copolymer micelle solutions. The critical micelle concentration, micelle aggregation number distribution and micelle structure were found to agree well with previous experimental and theoretical studies. The time-evolution of micelles from unimers is found to follow three stages: unimer consumption, equilibration of the number of micelles progressing mainly by the fusion/fission mechanism and slow adjustment of the weight-average aggregation number by micelle fusion, unimer and small aggregate exchange. The effect of polymer concentration, hydrophobic interaction energy and block length on the kinetics of micellization were also considered. By performing micelle hybridization simulations, we found the equilibrium chain exchange follows a first-order kinetic process and the characteristic time, mainly determined by chain expulsion and does not depend on polymer concentration. The chain exchange characteristic time, τ, increases exponentially with core block length, NA and interaction parameter between blocks, χAB as τ ~ exp(0.67χABNA). We also found that in contrast to theoretical predictions, chain exchange between micelles occurs more rapidly for micelles with a longer corona-block length due to a higher compatibility of diblock copolymers and therefore a lower potential barrier for chain expulsion.

Using coarse-grained molecular dynamics simulations we studied the equilibrium and rheological properties of dilute and semi-dilute solutions of head-to-tail associating supramolecular polymers with our newly-developed model for spontaneous reversible association. We found that for a given spacer length all shear-rate-dependent reduced viscosity data collapse into one master curve with two power-law regions with increasing slopes due to change of the degree of self-assembling under shear. The equilibrium viscosity is found to obey a power-law scaling dependence with exponent 1.5 on oligomer volume fraction, in agreement with experimental observations for several dilute or semi-dilute solutions of supramolecular polymers, implying that dilute and semi-dilute supramolecular polymer solutions exhibit high polydispersity, but may not be sufficiently entangled to follow the reptation mechanism of relaxation, expected for wormlike micelles.

Committee:

Elena Dormidontova (Advisor); Alexander Jamieson (Committee Member); Jay Mann (Committee Member); Lei Zhu (Committee Member)

Subjects:

Polymers

Keywords:

self-assembly dynamics; block copolymer micelles; supramolecular polymer; computer simulation; DPD simulation; Molecular Dynamics simulation; micelle dynamics; viscosity;

Buchman , Sherleena AnnSimulation in Interprofessional Education: A Case Study with Baccalaureate Nursing Faculty
Doctor of Philosophy (PhD), Ohio University, 2016, Instructional Technology (Education)
Nursing programs across the country are facing the challenge of providing students with optimal clinical skill learning experiences. Faculty members are rising to this challenge in a variety of ways, and current research in nursing education advocates the addition of interprofessional education to the nursing curriculum. History and governing bodies explain how nursing education can achieve this goal but faculty have to implement required and suggested changes. Further research is needed to gain insight into perceptions of the baccalaureate nursing faculty of interprofessional education and how the simulation in interprofessional experience contributes to overall patient safety. Patient safety is a priority in nursing and by using simulation as a safe place for a nursing student to learn, and then patient safety is enhanced. A qualitative case study was used to explore how the use of interprofessional education by baccalaureate nursing faculty can prepare nursing students to provide quality care to real patients. Baccalaureate nursing faculty from a large midwestern university in the United States of America participated in a case study that involved an interprofessional education simulation experience. Faculty were asked to participate in a set of interviews both before and after the completion of a simulated interprofessional education experience. Additionally, the case study participants were asked to provide narrative reflective journal writings of their experiences with any simulation interprofessional education experience or any other interprofessional experience. Additional methods of observation, field notes, and focus group, were used by the researcher to gain an understanding of the faculty lived experiences. Findings from this study will aid in curricular changes within healthcare education regarding simulation in interprofessional education.

Committee:

Teresa Franklin , PhD (Advisor); Kathleen Rose-Grippa , PhD (Committee Member); David Moore , PhD (Committee Member); Adah Ward-Randolph , PhD (Committee Member)

Subjects:

Education; Educational Technology; Health; Health Care; Health Education; Health Sciences; Nursing

Keywords:

interprofessional education; simulation; simulation in interprofessional education; nursing; nursing faculty; baccalaureate faculty; interprofessional simulation

Li, JiyuanConstruction Simulation of Wudian Using 3-D Graphics and Animations
Master of Science, The Ohio State University, 2015, Civil Engineering
Wudian, which is the realization of the wisdom of ancient architects characterized by a complex combination of components without using a single nail in the assembly process, is considered to be the noblest building category in ancient China. Based on the Gongcheng Zuofa, which is the only official construction document from the Qing dynasty, this thesis presents a systematical study of the construction simulation of Wudian using 3-D graphics and animation techniques. In the modeling process, all major structural timber components and connection types are presented step by step, and all the construction processes are simulated level by level. Then, a decision tree system (WDTS), a database of engineering drawings and illustrations of all the components and connections, and the animations of the construction process of Wudian are compiled into a Microsoft Visual Studio program. WDTS provides the user with detailed and comprehensive overall views of the construction simulation and a systematic understanding of how each component of Wudian was pre-fabricated and assembled. In conclusion, this thesis presents a new, effective method to simulate the construction of ancient structures such as the Wudian and to understand the beauty and wisdom of outstanding ancient Chinese architects.

Committee:

Fabian Tan (Advisor); Jeffrey Bielicki (Committee Member); Tarunjit Butalia (Committee Member)

Subjects:

Ancient Civilizations; Ancient History; Archaeology; Architectural; Architecture; Asian Studies; Civil Engineering; Classical Studies; Computer Engineering; Conservation; Design; Educational Software; Educational Technology; Engineering; History

Keywords:

Chinese Architecture; Construction Simulation; Dou Gong; Graphic 3-D Models; Qing Dynasty Architecture; Three-dimensional Animation; Three-dimensional Simulation; Timber Structure; Wudian; Wudian Construction; Wudian Roof

Alt, Aaron JProfile Driven Partitioning Of Parallel Simulation Models
MS, University of Cincinnati, 2014, Engineering and Applied Science: Computer Engineering
A considerable amount of research into effective parallelization for discrete event driven simulation has been conducted over the past few decades. However, most of this research has targeted the parallel simulation infrastructure; focusing on data structures, algorithms, and synchronization methods for the parallel and distributed simulation kernels. While this focus has successfully improved and refined the performance of parallel discrete event simulation kernels, little effort has been directed toward analyzing and preparing the simulation model itself for parallel execution. Model specific optimizations could have significant performance implications, but have been largely ignored. This fact is complicated by the lack of a widely used simulation and modeling language for many domains. The lack of a common language is, however, not entirely insurmountable. For example, the partitioning and assignment of objects from the simulation model onto the hardware platform is generally performed by the simulation infrastructure. While partitioning can have dramatic impacts on the communication frequencies between the concurrently executed objects, most existing parallel simulation infrastructures do little to address this opportunity. This thesis addresses the partitioning and assignment of objects within a simulation model for parallel execution. The specific target of this effort is to develop a partitioning and assignment strategy for use in the WARPED parallel simulation kernel that has been developed and maintained at the University of Cincinnati. The focus of the work is to develop a general purpose solution that can function for any simulation model that has been prepared for execution on the WARPED kernel. The specific solution exploits a sequential kernel from the WARPED project to pre-simulate the simulation model to obtain profile data regarding the frequency of events communicated between objects. This event frequency data is then used to develop partitions to minimize the amount of event exchanges between the objects in the different partitions. This partition information is then used during the initialization sequences of the WARPED kernel to assign each partition i to a unique processing node in the parallel cluster. This method is independent of the simulation model and compute platform. Experimental results with existing simulation models from the WARPED project show that this method can achieve up to a six-fold improvement in run time over the naive partitioning algorithm that was previously used by the WARPED kernel.

Committee:

Philip Wilsey, Ph.D. (Committee Chair); Fred Beyette, Ph.D. (Committee Member); Karen Davis, Ph.D. (Committee Member); Carla Purdy, Ph.D. (Committee Member)

Subjects:

Computer Engineering

Keywords:

DES;profile guided partitioning;PDES;discrete event simulation;parallel discrete event simulation;profiling

KUMAR, VINAYAKANALOG SIMULATION TIME REDUCTION BASED ON VARIABLE TOLERANCE RELAXATION
MS, University of Cincinnati, 2006, Engineering : Computer Engineering
Circuit simulation, arguably the most used tool amongst the tools required for very large circuit design, provides the means to validate electrical circuits and also to perform behavioral analysis. As the size and the complexity of circuits are growing exponentially, simulation of the circuits is taking enormous amount of processing time. As a result, simulation time is becoming a major bottleneck in performance. The purpose of this research work is to implement an algorithm to reduce simulation time of circuits under certain constraints. The algorithm is called the Analog Simulation Time Reduction using Variable Tolerance Relaxation (VTR) and can be particularly useful to a circuit designer who aspires to achieve desired simulation accuracy of only a part of a large analog circuit (rather than the entire). The main purpose of this algorithm is to maintain the desired accuracies of the variables, either node voltages or branch currents, in this small part of the circuit, while reducing the simulation time of the circuit. To achieve this objective, the algorithm uses a tolerance relaxation technique applied to all variables not of interest of designer while assuring the accuracy of all variables in interest to the designer. Variable- sensitivity analysis is automatically performed to determine the relaxed tolerances for uninteresting variables while maintaining desired accuracies of variables of interest. The VTR algorithm is executed during the initial stage of the simulation so that rest of the simulation can be done with relaxed tolerances of the variables. In this study, circuits were restricted to passive and linear-active circuits only. The experiment results showed maximum simulation time improvements of twenty-five percent over a broad range of passive and linear active circuits ranging in size from 23 to 91 elements. In no case did simulation time increase.

Committee:

Dr. Harold Carter (Advisor)

Keywords:

Simulation; Tolerance relaxation; Simulation time reduction

Krumpe, Norman JosephA COMPARISON OF SIMULATION OPTIMIZATION TECHNIQUES IN SOLVING SINGLE-OBJECTIVE, CONSTRAINED, DISCRETE VARIABLE PROBLEMS
Master of Computer Science, Miami University, 2005, Computer Science and Systems Analysis
Many analytic techniques are inadequate for finding optimal solutions to complex problems. Simulation is often used to model many such problems, but it is not always possible, or reasonable, to simulate every possible combination of control variables. Therefore, many simulation optimization techniques have been developed that attempt to iteratively search for a global optimum without testing every control parameter combination. The purpose of this study is to compare three such techniques: Simulated annealing, Hooke-Jeeves pattern search, and an algorithm that combines the essential features of simulated annealing and pattern search. These algorithms will be compared by applying them to several variants of three types of problems: two discrete-event simulations and one deterministic function. The results do not point to any one of these three algorithms outperforming the others. Rather results suggest that the performance of any of these algorithms depends on the many implementation decisions that must be made.

Committee:

Donald Byrkett (Advisor)

Subjects:

Computer Science

Keywords:

simulation optimization; simulation; simulated annealing; hooke-jeeves pattern search; no-free-lunch theorem

Rao, Dhananjai M.Study of Dynamic Component Substitutions
PhD, University of Cincinnati, 2003, Engineering : Computer Science and Engineering
High fidelity, high resolution models of systems need to be simulated for conducting in-depth studies of different scenarios and to ensure that crucial scalability issues do not dominate during validation of simulation results. However, simulation of large, high resolution models is a time consuming task. Consequently, the models are statically (i.e., before simulation commences) abstracted to improve performance of the simulations and minimize analysis overheads. However, abstraction improves performance by trading resolution, and possibly the fidelity, of the simulations –which defeats the purpose of studying high resolution models and magnifies the problems of validation! An alternate approach to improve the overall efficiency of simulation studies is to dynamically (i.e., during simulation) change the resolution of the model. Accordingly, this study proposes and explores the use of a novel methodology called Dynamic Component Substitution to enable dynamic changes to the resolution of the model. In DCS, a set of components (called a module) are dynamically substituted by a functionally equivalent component; thereby changing the resolution of a model without impacting the overall validity of the model. DCS improves the overall efficiency of simulations by enabling dynamic tradeoffs between several modeling and simulation related parameters. Therefore, it is crucial to use ideal sequences of component substitutions to ensure optimal simulation performance and meet the analysis requirements. However, identifying optimal sequences of DCS, particularly in parallel simulation environments is a complex task. Consequently, to ease effective use of DCS, a DCS algebra (i.e., a mathematical framework) along with a DCS Performance Prediction Methodology (DCSPPM) has been developed. This study empirically explores the practical applicability and effectiveness of DCS by applying it to several models from a variety of domains. The design and development of a modeling and parallel simulation environment to enable effective use of DCS is discussed. The issues involved in the implementation of DCSPPM are presented. The study also presents an empirical evaluation of the accuracy of the estimates generated by DCSPPM. The results from these studies indicate that DCS can significantly reduce simulation time in a predictable manner without impacting the overall validity of the simulation study.

Committee:

Dr. Philip A. Wilsey (Advisor)

Keywords:

modeling; multi-resolution, variable-resolution; parallel simulation; performance prediction; web-based modeling & simulation

Liang, JunSimulating Crimes and Crime Patterns Using Cellular Automata and GIS
PhD, University of Cincinnati, 2001, Arts and Sciences : Geography
The goal of this research is to simulate crime and crime pattern using cellular automata in a GIS environment. A crime occurs when a target has been attacked by an offender (or a group of offenders). Both target and offender have been studied extensively in criminology literature. However, interactions between them are rarely addressed due to their complexity. We have developed the concept of tension to link the activities of offenders and targets. Tension represents the impact of crimes on targets, including the reaction of targets to crimes. In this study, we applied cellular automata (CA) to simulate the diffusion of tension in space and time. Tension is modeled as the state variable in cellular automata. Other variables in the model are associated with tension either directly or indirectly. Individual offenders movements are simulated using Monte Carlo Simulation. This study focuses on one type of crime robbery of commercial properties. The simulation process runs through many iterations, each generating some individual crimes. The accumulation of individual crimes reveals crime patterns in space and time.The CA crime pattern simulation model is loosely coupled with Arcview GIS. Crime simulation model has been coded with C++, and it can be executed from an Avenue scrip inside Arcview. Arcview also serves the user interface of the model. The functions of the interface include configuration of a simulation, loading the simulation execution program, and analysis of the simulation output. We have tested the model in different scenarios. The result of these test runs helps uncover the impact of offenders and targets on each other. It also helps us understand how the impact is related to the spatial distribution of targets and offenders. Furthermore, it provides a viable solution to study the complex process of crime pattern generation, and enables criminologists to test their theories.

Committee:

Lin Liu (Advisor)

Keywords:

CELLULAR AUTOMATA; SPATIAL SIMULATION; GEOGRAPHIC INFORMATION SYSTEMS; OBJECT ORIENTED DESIGN; CRIME SIMULATION

Zoll, Brian M.Evaluating the E-consult Process for Diabetes Care Delivery at an Outpatient Care Clinic
Master of Science in Engineering (MSEgr), Wright State University, 2013, Industrial and Human Factors Engineering
The occurrence of one of the most common chronic conditions in the U.S., diabetes, is expected to rise 53% from 24 million cases in 2003 to 37 million cases in 2023. The U.S. Veterans Health Administration (VHA) is not immune to this. The VHA has experienced an $820 million increase spending on diabetes patients between 2000 and 2008. The VHA has tried to keep the growth of chronic care costs in check through improvements in patient access to care by expanding its network of community-based outpatient clinics. Other methods the VHA has used to curb chronic care spending costs are electronic health records (EHR), patient aligned care teams (PACT), telehealth, and e-consults. An e-consult is defined as an electronic communication between primary care physicians and specialists about general or patient-specific questions that may preclude the need for an in-person referral. The objective of this study was to evaluate the effects of increased e-consult demand on time-based outcomes, quantify the sensitivity of these outcomes to walk-in patient arrival rates, electronic view-alert notifications, and primary care physician (PCP) unavailability, and provide recommendations to alleviate the detrimental effects of factors that are determined to have a significant effect on these outcomes. We collected data from 5 different VHA outpatient clinics, which was used in a discrete event simulation (DES) model of a typical VA outpatient clinic. Factors analyzed in the model were e-consult demand, view-alert notification arrivals, walk-in patient arrivals, and PCP unavailability. After the model was validated with real data, a detailed experimental study was conducted to determine factors that have a significant effect on e-consult time-based outcomes, such as cycle time. A total of 495 experiments were run and statistical analysis of the results indicated that all four factors had a significant effect on e-consult cycle time (p<0.05). Results also showed that, generally, as e-consult demand increases, e-consult cycle time also increases. In a case where a PCP is always available, e-consult cycle time increases by only 5 days when demand is raised from 0.01 e-consults per day to 2.75 e-consults per day. However, the increase in cycle times is not linear. In the same case, as demand increases from 2.75 e-consults per day to 3.25 e-consults per day, cycle time increases by 17 days. To reduce the detrimental effect of PCP unavailability due to sickness and/or vacation on e-consult cycle time, we recommend splitting the additional notification and walk-in patient demand incurred by a PCP’s unavailability over the remaining available PCPs. In doing so, the cycle time does not increase drastically with an increase in e-consult demand, compared to the current strategy where the team leader assumes all the responsibility for the additional workload. Further research in the areas, such as walk-in patient arrival rate reduction methods, notification arrival rate reduction methods, and notification prioritization strategies, is likely to improve the time-based outcomes and meet the VA-set goals for e-consult completion. For example, if notification arrival rates are reduced by 20%, a 75% decrease in e-consult cycle times can be expected.

Committee:

Pratik Parikh, Ph.D. (Advisor); Jennie Gallimore, Ph.D. (Committee Member); Xinhui Zhang, Ph.D. (Committee Member)

Subjects:

Health Care Management; Industrial Engineering

Keywords:

E-consults; telehealth; PACT; outpatient clinic; VHA; veterans affairs; simulation; DES; discrete event simulation; walk-in patients; view-alert notifications

Ugwumba, Miracle CReliability Assessment Using Bootstrapping and Identification of Point of Diminishing Returns
Master of Science, University of Toledo, 2016, Mechanical Engineering
The safety of dynamic systems under random vibrations is usually quantified by using probabilistic methods. This is because of the inherent randomness associated with some parameters of a system. Simulation methods such as Monte Carlo Simulation (MCS), Separable Monte Carlo (SMC), and Importance Sampling (IS) are used to estimate the probability of failure of dynamic systems under random vibration. These methods are flawed or normally pose difficulties that prompt analyst to seek out other methods of simulation. In this research, bootstrapping was used to estimate the probability of failure and accuracy of dynamic systems under time-variant random vibration. MCS was used to compare the results obtained by bootstrapping. Increasing the degrees of freedom of a system results in an enormous increase in the total number of time histories of excitation created. This research focused on investigating the effect of increasing the degrees of freedom on the accuracy of the probability of failure of the systems under investigation. It was concluded that the points of diminishing returns of the standard deviation of the probability of failure is independent on the DOF of the systems under consideration.

Committee:

Nikolaidis Efstratios, Dr. (Committee Chair); Berhan Lesley, Dr. (Committee Member); Pourazady Mehdi, Dr. (Committee Member); Elahinia Mohammad , Dr. (Committee Member)

Subjects:

Engineering

Keywords:

Monte Carlo Simulation, Separable Monte Carlo Simulation, Bootstrapping

Iyer Krishnan, Jyothi LakshmiDesign of an interactive simulation tool for automatic generation and execution of a simulation program using siman
Master of Science (MS), Ohio University, 1993, Industrial and Manufacturing Systems Engineering (Engineering)

Manufacturing simulation used in the modeling and experimentation of a prototype requires a high level of expertise to achieve the desired task. This research proposes a method of configuring existing generic simulation models in manufacturing through an user-friendly and interactive interface between the non-expert user and the simulation language. Such a system could be a powerful, cost effective tool that provides the non-specialist access to simulation and the specialist increased productivity.

Committee:

H. Zwahlen (Advisor)

Subjects:

Engineering, Industrial

Keywords:

interactive simulation tool; automatic generation and execution simulation program; siman

Kim, YootaiControl of physics-based fluid animation using a velocity-matching method
Doctor of Philosophy, The Ohio State University, 2006, Computer and Information Science
Fluid animation remains one of the most challenging problems in computer graphics. Research on methods using physics-based simulation for animation has recently increased since this method has the capability of producing realistic fluid behavior. However, the primary drawback to using a simulation method is control of the resulting flow field because it is computationally expensive and highly nonlinear. The main goal of this research is to help users produce physically realistic fluid effects along a NURBS curve that can be specified directly or derived from an image or video. A linear-feedback velocity matching method is used to control the fluid flow. A physically realistic smoke flow along a user-specified path is generated by first procedurally producing a target velocity field, and then matching the velocity field obtained from a three-dimensional flow simulation with the target velocity field. The target velocity field can include various effects such as the small scale swirling motion characteristic of turbulent flows. The swirling motion is achieved by incorporating a vortex particle method into the linear feedback loop. The method is flexible in that any procedurally-generated target velocity field may be integrated with the fluid simulation. The efficacy of this approach is demonstrated by generating several three-dimensional flow animations for complex fluid paths, two-dimensional artistic fluid effects, and realistic tornado animations.

Committee:

Raghu Machiraju (Advisor)

Subjects:

Computer Science

Keywords:

computer graphics; computer animation; fluid animation; physics based animation; fluid simulation; smoke simulation; smoke animation; fluid animation control; path based flow control; linear feedback control; velocity matching; natural phenomena

Lafrenz, Nicholas K.Trojan Circuit Simulation and Evaluation
Master of Sciences (Engineering), Case Western Reserve University, 2010, EECS - Computer Engineering
This thesis introduces a purpose built simulator for the evaluation of Trojan circuit detection methods. Due to the increasing reliance of society and the government on integrated circuits and the increasing amount of outsourcing of the fabrication of said ICs, it has become necessary to be able to detect the presence of a Trojan circuit in a given IC. The simulator developed in this thesis uses the specific characteristics and necessities of the Trojan circuit detection problem and introduces a tool for use in evaluating these Trojan circuit detection techniques for accuracy and efficiency. Fault simulation techniques are utilized in novel ways to speed up Trojan circuit simulation, resulting in significant performance increases.

Committee:

Daniel Saab, PhD (Advisor); Christos Papachristou, PhD (Committee Member); Francis Merat, PhD (Committee Member)

Subjects:

Computer Science; Electrical Engineering

Keywords:

Trojan detection; Trojan simulation; circuit simulation

Schilder, Marit3 Dimensional Virtual Fabric and Garment Simulation
MDes, University of Cincinnati, 2008, Design, Architecture, Art and Planning : Design

This thesis explores the possibilities of virtual 3D garment simulation software for fashion design. The available software for simulating virtual clothing can roughly be separated into two groups. The first group of software is focused on animation and used to visualize cloth for games, movies, commercials. The second group is used for the virtual prototyping of garments in the apparel industry. Their main focus is to check a garment for the fit, and the 3D software is an extension on pattern making software that was already available.

Various software applications are explored in this thesis. An overview of functionality and a comparison of pros and cons are identified. Software aimed at the apparel industry is not very flexible in accurately visualizing a garment and especially the fabric of that garment. Through the use of sophisticated fabric design, this thesis shows how to use existing visualization techniques available in Autodesk Maya 8.5 differently to enhance the realism of virtual fabric and garment simulation.

Committee:

Jacqueline Burris, MSc (Committee Chair); Benjamin Meyer (Committee Member); Margaret Voelker-Ferrier, MA (Committee Member)

Subjects:

Design; Textile Research

Keywords:

3D; digital design; fashion; virtual fabric simulation; virtual garment simulation

Pai, VinodSimulation of two manufacturing systems for a car manufacturing company
Master of Science (MS), Ohio University, 1997, Industrial and Manufacturing Systems Engineering (Engineering)

Simulation of two manufacturing systems for a car manufacturing company

Committee:

Robert Judd (Advisor)

Subjects:

Engineering, Industrial

Keywords:

Queuing Event Simulation Tool; Simulation Control Language; QUEST

Wu, JinCRASHWORTHINESS SIMULATION OF ROADSIDE SAFETY STRUCTURES WITH DEVELOPMENT OF MATERIAL MODEL AND 3-D FRACTURE PROCEDURE
PhD, University of Cincinnati, 2000, Engineering : Engineering Mechanics
Impact simulation utilizing nonlinear FE analysis is rapidly becoming an effective tool in designing and evaluating roadside safety structures. The subject of this investigation is crashworthiness simulation of a highway guardrail system and implementation of a FE crash simulation code. In this study, a FE model is developed to accurately simulate a truck impacting a G4(1S) strong-post w-beam guardrail system, the most common system in the USA. A roadmap for simulation of highway safety structures is proposed and three major issues, which involve the use of springs to simulate component crashworthiness behavior, are investigated: rail to blockout bolt connection, soil-post-dynamic interaction, and effect of ends of guardrail. Both qualitative and quantitative validations of the crash simulation are presented and discussed. A systematic parametric study is consequently carried out to understand the effects of some parameters of the G4(1S) guardrail system for improvement of the system. Appropriate reduction of the embedment depth of the posts is anticipated to be a favorable approach for minimizing the risk of rollover of vehicles impacting the G4(1S) guardrail system. Since few attempts are described in the FE literature for modeling of 3-D nonlinear wood material and 3-D fracture processes, much effort in this dissertation is also focused on the implementation of a 3-D nonlinear wood material model and automated 3-D fracture procedure which are often needed in crash simulation of roadside safety structures. The DYNA3D explicit FE code is utilized in this study for implementation. The implemented 3-D wood model uses incremental-loading and curve-fitting techniques to trace the nonlinear behavior. User-defined nonlinear parameters are introduced to control the stiffness change based on the stiffness of previous iteration or initial stiffness. A modified Johnson rate dependent model is employed to account for the influence of strain rate. The model efficiently captured the nonlinear characteristics of wood, and therefore provides a new 3-D material modeling approach for wood materials. The implemented 3-D Fracture models have the capabilities of simulating automatic crack propagation without user intervention. An element deletion-and-replacement remeshing procedure is proposed for updating the explicit geometric description of evolving cracks. Fracture parameters such as stress intensity factors, energy release rates and crack tip opening angle are evaluated. The maximum circumferential stress criterion is utilized to predict the direction of crack advancement. Seven crack problems are presented to verify the effectiveness of the methodology. The simulated results are compared well with the element-free Galerkin (EFG) method. Mesh sensitivity and loading rate effects are studied in the validation of the presented procedure.

Committee:

Ala Tabiei (Advisor)

Keywords:

Roadside Safety; Crashworthiness Simulation; Guardrail Vehicle Impact; Wood Material Modeling; Fracture Simulation

Hay, Joshua AExperiments with Hardware-based Transactional Memory in Parallel Simulation
MS, University of Cincinnati, 2014, Engineering and Applied Science: Computer Engineering
Transactional memory is a concurrency control mechanism that dynamically determines when threads may safely execute critical sections of code. It does so by tracking memory accesses performed within a transactional region, or critical section, and detecting when memory operations conflict with other threads. Transactional memory provides the performance of fine-grained locking mechanisms with the simplicity of coarse-grained locking mechanisms. Parallel Discrete Event Simulation is a problem space that has been studied for many years, but still suffers from significant lock contention on SMP platforms. The pending event set is a crucial element to PDES, and its management is critical to simulation performance. This is especially true for optimistically synchronized PDES, such as those implementing the Time Warp protocol. Rather than prevent causality errors, events are aggressively scheduled and executed until a causality error is detected. This thesis explores the use of transactional memory as an alternative to conventional synchronization mechanisms for managing the pending event set in a time warp synchronized parallel simulator. In particular, this thesis examines the use of Intel’s hardware transactional memory, TSX, to manage shared access to the pending event set by the simulation threads. In conjunction with transactional memory, other solutions to contention are explored such as the use of multiple queues to hold the pending event set and the dynamic binding of threads to these multiple queues. For each configuration a comparison between conventional locking mechanisms and transactional memory access is performed to evaluate each within the WARPED parallel simulation kernel. In this testing, evaluation of both forms of transactional memory (HLE and RTM) implemented in the Haswell architecture were performed. The results show that RTM generally outperforms conventional locking mechanisms and that HLE provides consistently better performance than conventional locking mechanisms, up to as much as 27%.

Committee:

Philip Wilsey, Ph.D. (Committee Chair); Fred Beyette, Ph.D. (Committee Member); Carla Purdy, Ph.D. (Committee Member)

Subjects:

Computer Engineering

Keywords:

transactional memory;TSX;parallel simulation;parallel discrete event simulation;PDES;lock contention

Chien, Chih-HaoPOTENTIAL OPTIMAL GAIT PERFORMANCE OF MAUCH S-N-S PROSTHETIC KNEE CONFIGURATIONS AS PREDICTED BY DYNAMIC MODELING
Doctor of Engineering, Cleveland State University, 2014, Washkewicz College of Engineering
Patients with prosthetic legs routinely suffer from abnormal gait patterns which can cause health issues and eventually lower the quality of their lives. Despite the half-century advance in the technology of prosthetic knees, from the purely mechanical to microprocessor controlled systems, patient testing suggests that very little progress has been made in the quality of the kinetics and kinematics of amputee gait. Moreover, the cost of microprocessor controlled prosthetic knees may be 10 times more than the purely mechanical knees. While prosthetic knees have become more complex and expensive, it is not proven that the prosthetic knee is a central factor limiting amputee patient gait. The goal of this project is to determine the degree to which the Mauch S-N-S prosthetic knee limits the ability of a subject to achieve a close to normal gait pattern. In this research, we developed dynamic models of the Mauch S-N-S prosthetic knee based on gait-like motion tests of a Mauch knee cylinder and used the dynamic models in computational simulations to determine the best achievable gait, on the basis of obtaining near-to-normal gait kinematics and kinetics. Idealized assumptions were made for patient performance capability and characteristics of the other prosthetic leg components, to obtain the desired focus on knee capabilities and limitations. The results indicate that even with this relatively old technology prosthetic knee, subjects have the potential to walk much more normally than the patient-test data indicates. An extension of the study showed the significant interaction of the prosthetic knee and ankle with respect to achieving optimal gait. The methodology of this study can be applied to evaluation other knees, prosthetic components and prosthetic systems combining these components.

Committee:

William Smith, PhD (Advisor); Nolan Holland, PhD (Committee Co-Chair); Brian Davis, PhD (Committee Member); Howard Paul, PhD (Committee Member); Ton Van den Bogert, PhD (Committee Member); Aimin Zhou, PhD (Committee Member); Dan Simon, PhD (Committee Member)

Subjects:

Biomechanics; Biomedical Engineering; Biomedical Research

Keywords:

Mauch knee; gait simulation; prosthetic knee; robotic simulation; prosthetic knee characterization; optimal gait; musculoskeletal model; prosthetic knee test; transfemoral amputee;

Wu, XiaofengReduced Deformable Body Simulation with Richer Dynamics
Doctor of Philosophy, The Ohio State University, 2016, Computer Science and Engineering
Deformable body simulation can provide visually interesting results that have wide applications in both entertainment industries and scientific fields. However, it is computationally demanding when simulating detailed models with high degrees of freedom (DoFs). Subspace simulation is known for its ability to significantly accelerate the simulation by constraining the deformation of the model to lie within a prescribed low-dimensional space so that the high-DoFs dynamic system is reduced to a much lower one. State-of-the-art subspace simulation technique only allows around 100 simulation bases to be used for real-time applications. This limitation causes many interesting deformations results to be lost or even leads to deformation artifacts. In this dissertation, we focus on developing new techniques that empower subspace simulation to capture richer deformation dynamics. First, we propose a unified approach for simulating reduced multi-domain objects, where each domain of the object is simulated in its own subspace. The key challenge in implementing this method is how to handle the coupling among multiple deformable do- mains, so that the overall effect is free of gap or locking issues. We present a new domain decomposition framework that connects two disjoint domains through coupling elements. Under this framework, we present a unified simulation system that solves subspace deformations and rigid motions of all of the domains by a single linear solve. Since the coupling elements are part of the deformable body, their elastic properties are the same as the rest of the body and our system does not need stiffness parameter tuning. To quickly evaluate the reduced elastic forces and their Jacobian matrices caused by the coupling elements, we further develop two cubature optimization schemes using uniform and non-uniform cubature weights. Our experiment shows that the whole system can efficiently handle large and complex scenes, many of which cannot be easily simulated by previous techniques without limitations. Second, we designed a novel single-domain subspace solver that is superior to previous methods in terms of theoretical time complexity, actual running time and GPU implementation efficiency. Inspired by the recently proposed Projective Dynamics (PD) framework that makes use of a constant approximate Hessian for simulation, we proposed a new sub- space solver that utilizes BFGS’s self-correcting property to directly approximate the in- verse of the Hessian. Thus, GPU-unfriendly linear solve can be avoided. Moreover, our method does not require the expensive run-time evaluation of Hessian, which we identify as the bottleneck of existing subspace solver and is not GPU implementation friendly either. We designed experiments to show that our subspace solver can achieve several orders- of-magnitude speedup and much better scalability w.r.t. number of simulation bases over existing method.

Committee:

Huamin Wang (Advisor); Yusu Wang (Committee Member); Han-Wei Shen (Committee Member)

Subjects:

Computer Science

Keywords:

deformable body simulation;model reduction;subspace simulation;domain decomposition;

Li, Hong-MoA new electric power system Monte Carlo simulation model for transforming effects of storage plant operation from the chronological to the load duration domain
Master of Science (MS), Ohio University, 1981, Electrical Engineering & Computer Science (Engineering and Technology)

A new electric power system Monte Carlo simulation model for transforming effects of storage plant operation from the chronological to the load duration domain

Committee:

Brian Manhire (Advisor)

Keywords:

Monte Carlo simulation; Load Duration Oriented Simulation; Fortran Computer Code

Lyu, YeonhwanSimulations and Second / Foreign Language Learning: Improving communication skills through simulations
Master of Arts, University of Toledo, 2006, English (as a Second Language)
Communicative Language Teaching (CLT) is the current trend of second/foreign language learning. CLT has contributed to moving the focus from the forms of language to communication. However, it only changes the context and contents of lessons, focusing still on teaching “language” rather than teaching how to communicate. Language exists only in our mental domain; it does not exist in the physical domain (Yngve, 1996). Thus, our focus should be on learning/teaching how to communicate in a target speech community. This research re-examines the general notion of CLT and comprehensible input within a real-world perspective based on Yngve’s (1996) theory of Hard Science Linguistics. The main discussion of this research is the use of simulations in classrooms concerning learning/teaching how to communicate in the target speech community. Simulations can offer efficient and effective learning in the classrooms while providing naturalistic environments, which maximize the opportunities of creating real communication in EFL classrooms. The discussion presented here about simulations in language learning/teaching is based on Jones’ (1982) view. The research presented here explores the use of simulations in the classrooms with the aim of helping learners of EFL to improve their communicative ability.

Committee:

Douglas Coleman (Advisor)

Keywords:

Simulation; Simulation for Language Classroom; Language Learning / Teaching; Second / foreign Language Learning / Teaching; Human Linguistics; Hard Science Linguistics; comphrehensible input; Real-world Communication

KAMARAJ, JAYACHANDRANMODELING AND SIMULATION OF SINGLE SPOOL JET ENGINE
MS, University of Cincinnati, 2004, Engineering : Aerospace Engineering
A previously validated single spool,non-after burning turbojet engine model GEXX is converted to MATLAB / SIMULINK to illustrate the benefits of a graphical simulation system with a graphical user interface (GUI). The model simulates the dynamics of burner, compressor, turbine, and the gas volume after the turbine(before the nozzle) with compressor bleed, variable compressor stators and variable nozzle area as the inputs.The engine model can be used in four ways:# As a nonreal-time engine model for testing engine control algorithms. # As an embedded model within a control algorithm or observer. # As a system model for evaluating engine sensor and actuator models. # As a subsystem in a powertrain or vehicle dynamics model. Although developed and validated for a specific engine (the high speed spool of the GE16), the modeling procedure is generic enough to be used for a wide range of jet engines. The model which we used as reference for our model is created by matching the basic performance of the engine. The model allows varying the Power Lever Angle(PLA) and altitude during the simulation and the performance is recorded as the time history of the different variables. Similarly, the model was simulated at different flight velocities. The performance of the engine was studied by comparing the output variables at different PLA, altitude and velocity settings. The dynamics of the system can be clearly studied by using this SIMULINK model.

Committee:

Dr. Bruce Walker (Advisor)

Subjects:

Engineering, Aerospace

Keywords:

Single Spool Jet Engine; Turbojet Engine modeling simulation; Simulink modeling simulation; GE16 Engine GEXX

VENKATARAMANI, HARISHIMPROVING SPEED OF MIXED-SIGNAL SIMULATION THROUGH MODEL REDUCTION BY REDUCING BRANCH EQUATIONS USING S3IS ELABORATION DATA STRUCTURE
MS, University of Cincinnati, 2005, Engineering : Computer Engineering
The issue of performance of compile-driven mixed-signal simulation is a challenging problem with optimization techniques researched to speed-up the various phases of simulation. The matrix load phase of the analog simulation kernel has been found to consume the largest percentage of the total simulation time. In the worst case, the matrix load time is a cubic function of the number of equations in the system. Even a small reduction in the number of equations would significantly reduce the load time. Therefore, efforts have been directed towards reducing the matrix load time. The elaborated set of Characteristic Expressions (CEs) forms the input to the matrix load phase of the analog kernel. The CEs are formed either as a result of elaborating simultaneous statements or because of the association of the quantities and terminals. A reduction in the elaborated set of CEs would result in the reduction of both the matrix load and matrix solve times. This thesis presents algorithms that can reduce the number of conserved equations without altering the behavior of the model.

Committee:

Dr. Harold Carter (Advisor)

Keywords:

VHDL-AMS; Conserved systems; analog simulation; mixed-signal simulation

Ramezani-Dakhel, HadiBioengineered Metal Nanoparticles: Shape Control, Structure, and Catalytic Functionality
Doctor of Philosophy, University of Akron, 2015, Polymer Engineering
Bioengineered colloidal noble metal nanoparticles have received much attention thanks to their superior functionality in variety of applications including catalysis, nanoelectronics, biosensors, and biomedicine. Size, shape, and surface features dictate the functionality while the underlying mechanisms of interactions at the interface of biomolecules and nanoscale metal substrates are not yet fully understood. Here, we carried out extensive parallel molecular dynamics simulations to explain how soft epitaxy determines facet specificity of several mutant peptides (S7: SSFPQPN as base sequence) on various facets of Pt crystals. Binding differentials between facets strongly depend on the presence of phenyl rings, including “lie-flat” attractive configurations on the {111} surface that match the hexagonal pattern of epitaxial sites and repulsive “stand-up” configurations on the {100} surface. We uncovered the molecular mechanism of specific recognition of Pt nanocubes and the evolution of cubic shapes from cuboctahedral seed crystals by combinatorially selected T7 peptide (TLTTLTN). Accordingly, T7 molecules are attracted to the edges of nanocubes due to multiple times higher mobility of water molecules compared to center portions of the cube, accompanied by a unique match of polarizable atoms in T7 to the square pattern of epitaxial sites. Synthesis, characterization, and atomistic simulations showed a preference of peptide T7 towards {100} facets over {111} facets at intermediate concentration, that explains a higher yield of cubes. Similar arguments explain control principles for the growth of twinned versus single crystals. The ratio of {111} and {100} facets differs 60/40 (for twinned crystals) versus 35/65 (for single crystals) and peptides with adequately balanced adsorption strength to these facets at different nucleation stages elucidates the mechanism of twin formation. We systematically analyzed the ratio of {h k l} facets on Pd nanoparticles of different size, identified different atom types, and calculated the relative reaction rate of nanoparticles in carbon-carbon Stille coupling reactions using the Boltzmann-averaged abstraction energies of individual atoms, in excellent agreement with measured turnover frequencies in experiment. Additionally, we developed a protocol using molecular dynamics simulations in conjunction with atomic pair distribution function (PDF) analysis of high-energy X-ray diffraction (HE-XRD) patterns and reverse Monte Carlo (RMC) simulations to obtain accurate 3D atomic-scale structure of nanocatalysts. The functionality of nanoparticles in the model systems of carbon-carbon coupling and allyl alcohol hydrogenation reactions were examined computationally and experimentally, leading to accurate predictions of relative reaction rates. The current research efforts provide specific guidance in the design of functional metal nanoparticles and introduces a new paradigm for the design of the next generation of catalytically active nanostructures with superior functionality.

Committee:

Hendrik Heinz, Dr. (Advisor); Alamgir Karim, Dr. (Committee Member); Kevin Cavicchi, Dr. (Committee Member); Ali Dhinojwala, Dr. (Committee Member); Jutta Luettmer-Strathman, Dr. (Committee Member)

Subjects:

Biochemistry; Chemistry; Condensed Matter Physics; Molecules; Nanotechnology

Keywords:

metal nanoparticles; platinum; palladium; peptide; simulation; molecular dynamics; shape; catalysis; structure; tetrahedron nanoparticles; cubic nanoparticles; single twinned nanoparticles; pair distribution function; reverse Monte Carlo simulation

Next Page