idespread use of the Internet is giving rise to the need for collaborative applications that link... more idespread use of the Internet is giving rise to the need for collaborative applications that link users at remote sites. Many toolkits support the development of collaboration-aware applications-those developed specifically for cooperative work by multiple users. Another approach is collaboration transparency-the collaborative use of applications originally developed for a single user. When the runtime environment supports collaboration transparency, an application programmer need not write new code to make an application collaborative. Thus, collaboration transparency leverages the existing base of singleuser applications by extending them to collaborative use.
Abstract. This paper describes a computing environment named WBCSim that is intended to increase ... more Abstract. This paper describes a computing environment named WBCSim that is intended to increase the productivity of wood scientists conducting research on wood-based composite materials. WBCSim integrates Fortran 77-based simulation codes with a graphical front end, an optimization tool, and a visualization tool. WBCSim serves as a prototype for the design, construction and evaluation of larger scale problem solving (computing) environments. Several different wood-based composite material simulations are supported. A detailed ...
Virginia Tech was awarded a five year multi-investigator NSF-funded Science & Technology Center f... more Virginia Tech was awarded a five year multi-investigator NSF-funded Science & Technology Center for High Performance Polymeric Adhesives and Composites in 1989 (Grant# DMR 88-09714). The initial grant was extended for an additional five year period in February of 1992, with some restructuring of personnel and programs. The current NSF S&T Center award (Grant# DMR 9120004) is for the period February 1, 1992 to January 31, 1997 and is in the amount of $7,486,000. The Center director is Prof. J.
Abstract The GeoSim Interface Library (GIL) is a small, easy to use set of functions for building... more Abstract The GeoSim Interface Library (GIL) is a small, easy to use set of functions for building a graphical user interface. It was originally designed to support the user interface needs of Project GeoSim, a computer-aided education project for introductory geography classes. The original design for GIL was driven by the need to develop easy to use software that was portable to a variety of computing environments.
Swan is a data structure visualization system. It allows users to visualize the data structures a... more Swan is a data structure visualization system. It allows users to visualize the data structures and execution process of a C/C++ program. Swan views a data structure as a graph or collection of graphs. By "graph" we mean general directed and undirected graphs and special cases such as trees, lists and arrays.
This paper describes a new computing paradigm known as a problem solving environment (PSE), explo... more This paper describes a new computing paradigm known as a problem solving environment (PSE), explores the role this new paradigm might play in watershed management and land use change analysis, and compares PSEs to similar technologies such as decision support systems and geographic information systems. A prototypical watershed management PSE organizes and unifies the diverse collection of software typically associated with ecosystem models (hydrological, economic, and biological).
Abstract—This paper presents a sophisticated and efficient parallel scheme for the DIRECT global ... more Abstract—This paper presents a sophisticated and efficient parallel scheme for the DIRECT global optimization algorithm of Jones et al.(1993). Although several sequential implementations for this algorithm have been successfully applied to large scale MDO problems, few parallel versions of the DIRECT algorithm have addressed well algorithm characteristics such as a single starting point, an unpredictable workload, and a strong data dependency.
ABSTRACT We describe the current status of an ongoing research effort to develop a geographic inf... more ABSTRACT We describe the current status of an ongoing research effort to develop a geographic information system based on quadtrees. A linear quadtree encoding was implemented using a B-tree to organile the list of leaves and allow management of trees too large to fit in core memory. Several database query functions have been implemented including set operations, region property computations, map editing functions, and map subset and windowing functions.
Abstract: Numerous studies have been conducted to evaluate the effect of animated visualizations ... more Abstract: Numerous studies have been conducted to evaluate the effect of animated visualizations on students learning data structures, but few have attempted to evaluate the retention of information gained from visualizations. Our work focuses on comparing different media used for teaching data structures, particularly as they affect the learning process over time. Results from our empirical studies suggest that a combination of text and visualization helps students retain knowledge better than either approach alone.
We study data structures so that we can learn to write more efficient programs. But why must prog... more We study data structures so that we can learn to write more efficient programs. But why must programs be efficient when new computers are faster every year? The reason is that our ambitions grow with our capabilities. Instead of rendering efficiency needs obsolete, the modern revolution in computing power and storage capability merely raises the efficiency stakes as we attempt more complex tasks. The quest for program efficiency need not and should not conflict with sound design and clear coding.
We study data structures so that we can learn to write more efficient programs. But why must prog... more We study data structures so that we can learn to write more efficient programs. But why must programs be efficient when new computers are faster every year? The reason is that our ambitions grow with our capabilities. Instead of rendering efficiency needs obsolete, the modern revolution in computing power and storage capability merely raises the efficiency stakes as we computerize more complex tasks. The quest for program efficiency need not and should not conflict with sound design and clear coding.
Abstract Many protein regulatory models contain chemical species best represented as having multi... more Abstract Many protein regulatory models contain chemical species best represented as having multiple states. Such models stem from the potential for multiple levels of phosphorylation or from the formation of multiprotein complexes. We seek to support such models by augmenting an existing modeling and simulation system. Interactions between multistate species can lead to a combinatorial explosion in the potential state space. This creates a challenge when using Gillespie's stochastic simulation algorithm (SSA).
Abstract This paper presents a family of programming projects appropriate to a sophomore-level da... more Abstract This paper presents a family of programming projects appropriate to a sophomore-level data structures course, centered around the concept of a buffer pool serving as the access intermediary to a disk file. These projects provide a meaningful vehicle for practicing object-oriented design techniques and teach fundamental material on file processing and manipulating binary data. I begin with a concrete example, a heap stored on disk and mediated by a buffer pool.
While algorithm visualizations have proved valuable to the CS education community, even the bette... more While algorithm visualizations have proved valuable to the CS education community, even the better algorithm visualizations today are typically limited to instruction in the mechanics of how a given data structure or algorithm behaves. We present the concept of an “algorithm exploration,” which goes beyond the scope of algorithm visualizations to provide students with an opportunity to explore the relative merits of alternative solutions for a particular problem.
Abstract The elevation pyramid, a pyramid-based representation for storing gridded elevation data... more Abstract The elevation pyramid, a pyramid-based representation for storing gridded elevation data, is described. Associated with the root of the pyramid is the corresponding grid's minimum elevation and range. The elevation value for a specified grid pixel is calculated by transversing a path from the pyramid root to the corresponding leaf node. As the transversal proceeds, the minimum and range values are refined by interpreting the codes stored at each node along the path.
Abstract In this paper, we present our vision for OpenDSA, an open-source, community-based effort... more Abstract In this paper, we present our vision for OpenDSA, an open-source, community-based effort to create a complete active-eBook for Data Structures and Algorithms courses at the undergraduate level. We define active-eBooks as going beyond classic hyper textbooks, being a close integration of text and images with interactive visualizations/simulations and assessment activities.
This report documents the research conducted under Phase II of Contract DAAK70-81-C-0059/P00007. ... more This report documents the research conducted under Phase II of Contract DAAK70-81-C-0059/P00007. The report was prepared for the US Army Engineer Topographic Laboratories (ETL), Ft. Belvoir, Virginia 22060. The Contracting Officer'3 Representative was Mr. Joseph A. Rastatter.
Abstract: Swan is a data structure visualization system. Its main purpose is to allow the user to... more Abstract: Swan is a data structure visualization system. Its main purpose is to allow the user to visualize the data structures and the basic execution process of a C/C++ program. Swan views a data structure as a graph or a collection of graphs. By “graph,” we include both general directed and undirected graphs and special cases such as trees, lists and arrays.
idespread use of the Internet is giving rise to the need for collaborative applications that link... more idespread use of the Internet is giving rise to the need for collaborative applications that link users at remote sites. Many toolkits support the development of collaboration-aware applications-those developed specifically for cooperative work by multiple users. Another approach is collaboration transparency-the collaborative use of applications originally developed for a single user. When the runtime environment supports collaboration transparency, an application programmer need not write new code to make an application collaborative. Thus, collaboration transparency leverages the existing base of singleuser applications by extending them to collaborative use.
Abstract. This paper describes a computing environment named WBCSim that is intended to increase ... more Abstract. This paper describes a computing environment named WBCSim that is intended to increase the productivity of wood scientists conducting research on wood-based composite materials. WBCSim integrates Fortran 77-based simulation codes with a graphical front end, an optimization tool, and a visualization tool. WBCSim serves as a prototype for the design, construction and evaluation of larger scale problem solving (computing) environments. Several different wood-based composite material simulations are supported. A detailed ...
Virginia Tech was awarded a five year multi-investigator NSF-funded Science & Technology Center f... more Virginia Tech was awarded a five year multi-investigator NSF-funded Science & Technology Center for High Performance Polymeric Adhesives and Composites in 1989 (Grant# DMR 88-09714). The initial grant was extended for an additional five year period in February of 1992, with some restructuring of personnel and programs. The current NSF S&T Center award (Grant# DMR 9120004) is for the period February 1, 1992 to January 31, 1997 and is in the amount of $7,486,000. The Center director is Prof. J.
Abstract The GeoSim Interface Library (GIL) is a small, easy to use set of functions for building... more Abstract The GeoSim Interface Library (GIL) is a small, easy to use set of functions for building a graphical user interface. It was originally designed to support the user interface needs of Project GeoSim, a computer-aided education project for introductory geography classes. The original design for GIL was driven by the need to develop easy to use software that was portable to a variety of computing environments.
Swan is a data structure visualization system. It allows users to visualize the data structures a... more Swan is a data structure visualization system. It allows users to visualize the data structures and execution process of a C/C++ program. Swan views a data structure as a graph or collection of graphs. By "graph" we mean general directed and undirected graphs and special cases such as trees, lists and arrays.
This paper describes a new computing paradigm known as a problem solving environment (PSE), explo... more This paper describes a new computing paradigm known as a problem solving environment (PSE), explores the role this new paradigm might play in watershed management and land use change analysis, and compares PSEs to similar technologies such as decision support systems and geographic information systems. A prototypical watershed management PSE organizes and unifies the diverse collection of software typically associated with ecosystem models (hydrological, economic, and biological).
Abstract—This paper presents a sophisticated and efficient parallel scheme for the DIRECT global ... more Abstract—This paper presents a sophisticated and efficient parallel scheme for the DIRECT global optimization algorithm of Jones et al.(1993). Although several sequential implementations for this algorithm have been successfully applied to large scale MDO problems, few parallel versions of the DIRECT algorithm have addressed well algorithm characteristics such as a single starting point, an unpredictable workload, and a strong data dependency.
ABSTRACT We describe the current status of an ongoing research effort to develop a geographic inf... more ABSTRACT We describe the current status of an ongoing research effort to develop a geographic information system based on quadtrees. A linear quadtree encoding was implemented using a B-tree to organile the list of leaves and allow management of trees too large to fit in core memory. Several database query functions have been implemented including set operations, region property computations, map editing functions, and map subset and windowing functions.
Abstract: Numerous studies have been conducted to evaluate the effect of animated visualizations ... more Abstract: Numerous studies have been conducted to evaluate the effect of animated visualizations on students learning data structures, but few have attempted to evaluate the retention of information gained from visualizations. Our work focuses on comparing different media used for teaching data structures, particularly as they affect the learning process over time. Results from our empirical studies suggest that a combination of text and visualization helps students retain knowledge better than either approach alone.
We study data structures so that we can learn to write more efficient programs. But why must prog... more We study data structures so that we can learn to write more efficient programs. But why must programs be efficient when new computers are faster every year? The reason is that our ambitions grow with our capabilities. Instead of rendering efficiency needs obsolete, the modern revolution in computing power and storage capability merely raises the efficiency stakes as we attempt more complex tasks. The quest for program efficiency need not and should not conflict with sound design and clear coding.
We study data structures so that we can learn to write more efficient programs. But why must prog... more We study data structures so that we can learn to write more efficient programs. But why must programs be efficient when new computers are faster every year? The reason is that our ambitions grow with our capabilities. Instead of rendering efficiency needs obsolete, the modern revolution in computing power and storage capability merely raises the efficiency stakes as we computerize more complex tasks. The quest for program efficiency need not and should not conflict with sound design and clear coding.
Abstract Many protein regulatory models contain chemical species best represented as having multi... more Abstract Many protein regulatory models contain chemical species best represented as having multiple states. Such models stem from the potential for multiple levels of phosphorylation or from the formation of multiprotein complexes. We seek to support such models by augmenting an existing modeling and simulation system. Interactions between multistate species can lead to a combinatorial explosion in the potential state space. This creates a challenge when using Gillespie's stochastic simulation algorithm (SSA).
Abstract This paper presents a family of programming projects appropriate to a sophomore-level da... more Abstract This paper presents a family of programming projects appropriate to a sophomore-level data structures course, centered around the concept of a buffer pool serving as the access intermediary to a disk file. These projects provide a meaningful vehicle for practicing object-oriented design techniques and teach fundamental material on file processing and manipulating binary data. I begin with a concrete example, a heap stored on disk and mediated by a buffer pool.
While algorithm visualizations have proved valuable to the CS education community, even the bette... more While algorithm visualizations have proved valuable to the CS education community, even the better algorithm visualizations today are typically limited to instruction in the mechanics of how a given data structure or algorithm behaves. We present the concept of an “algorithm exploration,” which goes beyond the scope of algorithm visualizations to provide students with an opportunity to explore the relative merits of alternative solutions for a particular problem.
Abstract The elevation pyramid, a pyramid-based representation for storing gridded elevation data... more Abstract The elevation pyramid, a pyramid-based representation for storing gridded elevation data, is described. Associated with the root of the pyramid is the corresponding grid's minimum elevation and range. The elevation value for a specified grid pixel is calculated by transversing a path from the pyramid root to the corresponding leaf node. As the transversal proceeds, the minimum and range values are refined by interpreting the codes stored at each node along the path.
Abstract In this paper, we present our vision for OpenDSA, an open-source, community-based effort... more Abstract In this paper, we present our vision for OpenDSA, an open-source, community-based effort to create a complete active-eBook for Data Structures and Algorithms courses at the undergraduate level. We define active-eBooks as going beyond classic hyper textbooks, being a close integration of text and images with interactive visualizations/simulations and assessment activities.
This report documents the research conducted under Phase II of Contract DAAK70-81-C-0059/P00007. ... more This report documents the research conducted under Phase II of Contract DAAK70-81-C-0059/P00007. The report was prepared for the US Army Engineer Topographic Laboratories (ETL), Ft. Belvoir, Virginia 22060. The Contracting Officer'3 Representative was Mr. Joseph A. Rastatter.
Abstract: Swan is a data structure visualization system. Its main purpose is to allow the user to... more Abstract: Swan is a data structure visualization system. Its main purpose is to allow the user to visualize the data structures and the basic execution process of a C/C++ program. Swan views a data structure as a graph or a collection of graphs. By “graph,” we include both general directed and undirected graphs and special cases such as trees, lists and arrays.
Uploads
Papers by Cliff Shaffer