Osman Yaşar
State University of New York @ Brockport, Education, Faculty Member
- I am a scholar with a broad interest in science, mathematics, engineering, and technology.edit
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ABSTRACT KIVA-3 is the latest version of a 3-D Finite Difference CFD code developed by Amsden for combustion engine simulations. A distributed-memory implementation has many advantages for problems that hardly fit affordable existing... more
ABSTRACT KIVA-3 is the latest version of a 3-D Finite Difference CFD code developed by Amsden for combustion engine simulations. A distributed-memory implementation has many advantages for problems that hardly fit affordable existing memory banks. Previous attempts to parallelize KIVA-2 by Yasar, et al. were focused mostly on diffusion solvers because of their heavy time consumption during execution. The study suggested a complete parallelization of the code, including advection and spray dynamics, along with the use of a block-wise decomposition scheme to assure an efficient load balancing and a low communication/computation ratio. Here, the authors report rather a general analysis of the issues involved in such a distributed implementation for the latest version of the code, KIVA-3, on MIMD parallel systems. A more detailed analysis of the code and corresponding algorithms have already been implemented by Yasar and will be published soon.
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Detailed experimental measurements of a compressor (pressure, temperature, speed) are not easily available because of size, cost, and access difficulties. A comprehensive computer model is necessary to obtain pressure-volume diagrams for... more
Detailed experimental measurements of a compressor (pressure, temperature, speed) are not easily available because of size, cost, and access difficulties. A comprehensive computer model is necessary to obtain pressure-volume diagrams for the compressor. The valve is a key component of a compressor as it determines both the efficiency and reliability of the compressor. The valves operate as a result of pressure differences between the ports and the gas chamber. Undesired vibrations and fatigue fracture of thin valves (0.2 mm steel sheet) have not been well understood and experimental difficulties do not allow a thorough analysis of the causes. Initial investigations and modifications to KIVA-3V showed this code can be used to model both gas and suction valve motion. Since the code was written for internal combustion engines, its adaptation to compressors proved to be a difficult task, particularly because of the orientation and complexity of valves. Extensive modifications were made to model an angularly moving valve system, however as we moved down from engine scale (10 cm) to compressor scale (1 cm), grid resolution became a challenge from time to time. Preliminary results showed that the design of the suction valve and the chamber impacts the pressure difference between the input port and the gas chamber. The higher the piston speed, the lower the pressure of the gas, making it perhaps more plausible to avoid premature valve closings at higher speeds. Even though it is still under investigation, valve location and the orientation of its loose end makes a difference to the pressure, suggesting that new designs may be necessary by manufacturers. Experimental data will be needed to validate our model and verify our observations. Future steps include adding a discharge valve and a fluid-solid interface (FSI) module to the modified KIVA-3V code in order to predict the motion of the valves as a result of their interaction with the chamber gas.
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Teaching with technology remains as a challenge for STEM teachers. Making judicious choices of when, what and how specific tools and pedagogies to use in the teaching of a topic can be improved with the help of curriculum inventories,... more
Teaching with technology remains as a challenge for STEM teachers. Making judicious choices of when, what and how specific tools and pedagogies to use in the teaching of a topic can be improved with the help of curriculum inventories, training, and practice but as new and more capable technologies arrive, such resources and experience do not often transfer to new circumstances. Even within the realm of a particular technology, the choice of which tool would be better to teach a topic needs judicious thinking. This article presents a qualitative case study in which pre-service and in-service teachers are trained about not just the use but also basic operating principles of a technology in an attempt to enhance its integration into teaching in a more permanent, constructivist, and tool-independent way. The focus of our work is computational modeling and simulation technology (CMST). Based on pre/post activity surveys, focus group interviews, and artifacts, the results suggest that if teachers move beyond ‘using’ tools and learn the basic mathematical and computational principles of modeling and simulation, they can construct their own models, rather than using readymade ones, navigate between multiple tools that operate on the same principles, and as a result gain confidence to more judiciously decide under different circumstances as to what tools might better facilitate teaching of a topic.
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Presents a parallel computational model to simulate plasmas in the radiation-magnetohydrodynamics (R-MHD) framework. The solution of the radiation field usually dominates the R-MHD computation. The authors solve the linear Boltzmann... more
Presents a parallel computational model to simulate plasmas in the radiation-magnetohydrodynamics (R-MHD) framework. The solution of the radiation field usually dominates the R-MHD computation. The authors solve the linear Boltzmann equation for the radiation field intensity, using the deterministic SN discrete ordinates method. Choosing an energy-domain decomposition the authors have implemented the SN method on a parallel processor, the Intel iPSC/860, and the speedups are very favorable. Increasing almost linearly with the number of processors, the speedup reaches 14 on 16 processors. A comparison of timing measurements between a single processor CRAY Y-MP and a 16 processor iPSC/860 implementation strongly favors parallelism by a factor of 3.7
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This article describes computational pedagogy, an approach to teaching principles of computing aided by modeling and simulation. Besides fostering abstraction skills in students, this approach motivates them to learn programming and... more
This article describes computational pedagogy, an approach to teaching principles of computing aided by modeling and simulation. Besides fostering abstraction skills in students, this approach motivates them to learn programming and supports both the deductive and inductive forms of instruction. Specifically, the article reports how computational pedagogy was implemented in the context of a professional development program for teachers and what impact that professional development program had on STEM teaching and learning in secondary schools.
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An explicit adaptive-grid finite differencing method for one-dimensional radiation-magnetohydrodynamics computations is described. Based on the equidistribution principle, this explicit procedure moves the grid points to regions with high... more
An explicit adaptive-grid finite differencing method for one-dimensional radiation-magnetohydrodynamics computations is described. Based on the equidistribution principle, this explicit procedure moves the grid points to regions with high spatial gradients in physical quantities, such as temperature, mass density, pressure, and momentum. The governing magnetic field, radiative transfer, and hydrodynamics equations are transformed to the moving adaptive reference frame. The time and spatially dependent radiation field is determined by solving the radiative transfer equation with the multigroup discrete ordinate S[sub N] method with implicit time differencing. The magnetic field is solved through a diffusion equation resulted from Maxwell's equations and Ohm's law. The field equations are solved using a first-order upwind spatial differencing and explicit time differencing scheme. The coupling between the fluid and radiation field is treated explicitly by first solving for the radiation field and then the fluid equations. A conservation differencing scheme based on the control volume approach is chosen to retain the conservative nature of the governing equations. 26 refs., 14 figs., 3 tabs.
Research Interests: Engineering, Mathematics, Physics, Computational Physics, Plasma Physics, and 15 moreMagnetohydrodynamics, Fluid Mechanics, Mesh generation, Magnetic field, Mathematical Sciences, Physical sciences, PARTIAL DIFFERENTIAL EQUATION, Reference Frame, Grid, First Order Logic, Radiative Transfer, Acoustic Diffusion Equation Model, Finite Difference Method, Differential equation, and diffusion equation
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Description/Abstract An adaptive grid finite difference scheme was derived for simulating non-linear and unsteady one dimensional (planar, cylindrical and spherical) fluid flow by adapting to steep gradients in different physical... more
Description/Abstract An adaptive grid finite difference scheme was derived for simulating non-linear and unsteady one dimensional (planar, cylindrical and spherical) fluid flow by adapting to steep gradients in different physical quantities. The scheme is applied to z-...
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... Computer Physics Communications Computer Physics Communications 69 (1992) 439458 NorthHolland Osman Yasar and Gregory A. Moses Department ... a con issue) Licensing provisions: none Computers: CRAY XMP and YMP: Installation: San Diego... more
... Computer Physics Communications Computer Physics Communications 69 (1992) 439458 NorthHolland Osman Yasar and Gregory A. Moses Department ... a con issue) Licensing provisions: none Computers: CRAY XMP and YMP: Installation: San Diego Supercomputer Center ...
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ABSTRACT We describe math modeling and computer simulations as a new pedagogical approach to math and science education. Computational approach to Math, Science, and Technology (CMST) involves inquiry-based, project-based, and team-based... more
ABSTRACT We describe math modeling and computer simulations as a new pedagogical approach to math and science education. Computational approach to Math, Science, and Technology (CMST) involves inquiry-based, project-based, and team-based instruction. It takes the constructivist approach recommended by national learning standards. Our college has formed a partnership with local school districts to study impact of CMST on student achievement in math and science. We have trained more than 60 middle and high school teachers and teacher candidates. Preliminary results indicate that CMST-based professional development contributed an increase in passing rate (from 39% to 85%) of Rochester City School District in New York State high school math exam. This paper establishes relevant literature supporting CMST as an important scientific and educational methodology. KeywordsComputational Math-Science-and Technology-Pedagogy-K-12 education
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Research Interests: Computer Science, Physics, Magnetohydrodynamics, Turbulence, Combustion, and 12 moreDistributed Shared Memory System, Numerical Simulation, Mathematical Sciences, Turbulent Flow, Computers and Mathematics with Applications 59 (2010) 35783582, Message Passing, Parallel Algorithm, Scalability, Radiative Transfer, Three Dimensional, Massively parallel computing, and Inertial Confinement Fusion
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The partitioned inverse method has been demonstrated to be quite effective for parallel sparse matrix solutions on massively parallel machines. Though experiments on CM-2 have illustrated the advantage of using partitions, Intel iPSC/860... more
The partitioned inverse method has been demonstrated to be quite effective for parallel sparse matrix solutions on massively parallel machines. Though experiments on CM-2 have illustrated the advantage of using partitions, Intel iPSC/860 multiprocessor only favors fewer and denser partitions, particularly in the case of extremely sparse matrices. Different decomposition and communication algorithms are investigated here on the iPSC/860 to improve the performance. The decomposition is done in an interleave fashion in two different directions (row-wise and column-wise). The need for synchronization due to the interchange of intermediate solution vectors makes load balancing an important factor in obtaining an optimum performance.
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The notion of teaching experts’ habits of mind (e.g., computational thinking and scientific thinking) to novices seems to have inspired many educators and researchers worldwide. In particular, a great deal of efforts has been invested in... more
The notion of teaching experts’ habits of mind (e.g., computational thinking and scientific thinking) to novices seems to have inspired many educators and researchers worldwide. In particular, a great deal of efforts has been invested in computational thinking (CT) and its manifestations in different fields. However, there remain some troubling spots in CT education as far as how to teach it at different levels of education. The same argument applies to teaching scientific thinking (ST) skills. A remedy has been suggested to narrow CT and ST skillsets down to core cognitive competencies so they can be introduced in early and middle grades and continue to be nurtured during secondary and post-secondary years. Neuroscientists suggest that the act of (computational) thinking is strongly linked to the acts of information storage/retrieval by our brain. Plus, years of research have shown that retrieval practices promote not only knowledge retention but also inductive reasoning and deduct...
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Hpcu '99 New Trends in High Performance Computing Annual Conference for Vendor-independent Hpc Users Group Conference Program Conference Organizers and Committees General Chairs Conference Chair Program Chair Local Organizers Is Hpc Platform Portability a Fallacy? 2:30 Calculating Radiative Heat Tramore
8:00 AM Bus leaves campus for hotel pickups 8:40 10:00 AM Bus leaves campus for hotel pickups 10:30 Departure to the Hamptons for picnic, wine-tasting tour, shopping, and beach. 6:00 PM Bus leaves Hamptons, returns to Stony Brook and... more
8:00 AM Bus leaves campus for hotel pickups 8:40 10:00 AM Bus leaves campus for hotel pickups 10:30 Departure to the Hamptons for picnic, wine-tasting tour, shopping, and beach. 6:00 PM Bus leaves Hamptons, returns to Stony Brook and hotels approximately 7:30.
The construct of computational thinking (CT) was popularized a decade ago as an “attitude and skillset” for everyone. However, since it is equated with thinking by computer scientists, the teaching of these skills poses many challenges at... more
The construct of computational thinking (CT) was popularized a decade ago as an “attitude and skillset” for everyone. However, since it is equated with thinking by computer scientists, the teaching of these skills poses many challenges at K-12 because of their reliance on the use of electronic computers and programming concepts that are often found too abstract and difficult by young students. This article links CT – i.e., thinking generated and facilitated by a computational device – to our typical fundamental cognitive processes by using a model of mind that is aligned with research in cognitive psychology and neuroscience and supported by a decade of empirical data on teaching and learning. Our model indicates that associative and distributive aspects of information storage, retrieval, and processing by a computational mind is the very essence of thinking, particularly deductive and inductive reasoning. We all employ these cognitive processes but not everyone uses them as iterati...
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The ideas in this article resulted from many years of research in engineering, physics, computer, and cognitive sciences, as well as teaching experience in college and secondary schools. While its main purpose is to discuss the... more
The ideas in this article resulted from many years of research in engineering, physics, computer, and cognitive sciences, as well as teaching experience in college and secondary schools. While its main purpose is to discuss the universality of modeling and simulation process and its pedagogical use in teaching, there are several conclusions to be drawn.
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A decade of discourse to capture the essence of computational thinking has resulted in a broad set of skills whose teaching continue to pose challenges because of the reliance on the use of electronic computers and programming concepts.... more
A decade of discourse to capture the essence of computational thinking has resulted in a broad set of skills whose teaching continue to pose challenges because of the reliance on the use of electronic computers and programming concepts. This article not only links computational thinking skills to fundamental cognitive competencies but also describes pedagogical tools that have proven effective in teaching them at early ages.
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We report two aspects of a computational molecular dynamics study of large-scale problems on a distributed-memory MIMD parallel computer: (1) efficiency and scalability results on Intel Paragon parallel computers with up to 512 nodes and... more
We report two aspects of a computational molecular dynamics study of large-scale problems on a distributed-memory MIMD parallel computer: (1) efficiency and scalability results on Intel Paragon parallel computers with up to 512 nodes and (2) a new method for dynamic load balancing.