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2003

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Articles 2311 - 2340 of 3876

Full-Text Articles in Physical Sciences and Mathematics

Determination Of The Topological Structure Of An Orbifold By Its Group Of Orbifold Diffeomerphisms, Joseph E. Borzellino, Victor Brunsden Jan 2003

Determination Of The Topological Structure Of An Orbifold By Its Group Of Orbifold Diffeomerphisms, Joseph E. Borzellino, Victor Brunsden

Mathematics

We show that the topological structure of a compact, locally smooth orbifold is determined by its orbifold diffeomorphism group. Let DiffrOrb (O) denote the Cr orbifold diffeomorphisms of an orbifold O. Suppose that Φ: DiffrOrb(O1) → DiffrOrb (O2) is a group isomorphism between the the orbifold diffeomorphism groups of two orbifolds O1 and O2. We show that Φ is induced by a homeomorphism h: XO1 → XO2 , where XO denotes the underlying topological …

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A Tail-Recursive Semantics For Stack Inspections, John Clements, Mathias Felleisen Jan 2003

A Tail-Recursive Semantics For Stack Inspections, John Clements, Mathias Felleisen

Computer Science and Software Engineering

Security folklore holds that a security mechanism based on stack inspection is incompatible with a global tail call optimization policy. An implementation of such a language may have to allocate memory for a source-code tail call, and a program that uses only tail calls (and no other memory-allocating construct) may nevertheless exhaust the available memory. In this paper, we prove this widely held belief wrong. We exhibit an abstract machine for a language with security stack inspection whose space consumption function is equivalent to that of the canonical tail call optimizing abstract machine. Our machine is surprisingly simple and suggests …

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Impulsive Differential Equations With Non-Local Conditions, Robert Knapik Jan 2003

Impulsive Differential Equations With Non-Local Conditions, Robert Knapik

Morehead Electronic Journal of Applicable Mathematics Archives

No abstract provided.

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Automatic Statistical Processing Of Multibeam Echosounder Data, Brian R. Calder Jan 2003

Automatic Statistical Processing Of Multibeam Echosounder Data, Brian R. Calder

Center for Coastal and Ocean Mapping

This paper presents the CUBE (Combined Uncertainty and Bathymetry Estimator) algorithm. Our aim is to take advantage of statistical redundancy in dense Multibeam Echosounder data to identify outliers while tracking the uncertainty associated with the estimates that we make of the true depth in the survey area. We recognise that a completely automatic system is improbable, but propose that significant benefits can still be had if we can automatically process good quality data, and highlight areas that probably need further attention. We outline CUBE and its associated support structures, and apply it to a dataset from Woods Hole, MA, USA. …

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On Approximating Weighted Sums With Exponentially Many Terms, Deepak Chawla, Lin Li, Stephen Scott Jan 2003

On Approximating Weighted Sums With Exponentially Many Terms, Deepak Chawla, Lin Li, Stephen Scott

CSE Technical Reports

Multiplicative weight-update algorithms such as Winnow and Weighted Majority have been studied extensively due to their on-line mistake bounds’ logarithmic dependence on N, the total number of inputs, which allows them to be applied to problems where N is exponential. However, a large N requires techniques to efficiently compute the weighted sums of inputs to these algorithms. In special cases, the weighted sum can be exactly computed efficiently, but for numerous problems such an approach seems infeasible. Thus we explore applications of Markov chain Monte Carlo (MCMC) methods to estimate the total weight. Our methods are very general and …

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Combining Ordering Heuristics And Bundling Techniques For Solving Finite Constraint Satisfaction Problems, Amy Beckwith, Berthe Y. Choueiry Jan 2003

Combining Ordering Heuristics And Bundling Techniques For Solving Finite Constraint Satisfaction Problems, Amy Beckwith, Berthe Y. Choueiry

CSE Technical Reports

We investigate techniques to enhance the performance of backtrack search procedure with forward-checking (FC-BT) for finding all solutions to a finite Constraint Satisfaction Problem (CSP). We consider ordering heuristics for variables and/or values and bundling techniques based on the computation of interchangeability. While the former methods allow us to traverse the search space more effectively, the latter allow us to reduce it size. We design and compare strategies that combine static and dynamic versions of these two approaches. We show empirically the utility of dynamic variable ordering combined with dynamic bundling in both random problems and puzzles.

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E-Commerce Broker Prototype Implementation And Investigation, Rohini Krishnapura Jan 2003

E-Commerce Broker Prototype Implementation And Investigation, Rohini Krishnapura

CSE Technical Reports

Personalization has become a popular solution to today’s Ecomerce challenges. Various personalization techniques have been researched and marketed. But, one technique may not suit all businesses. What is required is a mechanism to enable different policies based possibly on different personalization techniques. The Ebroker architecture presented here provides a mechanism to enable different policies with minimal effort. We present here the various components of the architecture as well as the features that the architecture provides. The details of a prototype design and implementation are also discussed.

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A Dynamic Real-Time Scheduling Algorithm For Reduced Energy Consumption In I/O Devices, Rohini Krishnapura, Steve Goddard Jan 2003

A Dynamic Real-Time Scheduling Algorithm For Reduced Energy Consumption In I/O Devices, Rohini Krishnapura, Steve Goddard

CSE Technical Reports

In real-time systems, Dynamic Power Management (DPM) techniques have traditionally centered on the CPU with less focus given to I/O. However, I/O-based DPM techniques have been popularly researched in non-real-time systems. These techniques focus on switching I/O devices to low power states based on some policy. These methods, however, are not applicable to realtime environments because of the non-deterministic nature of the policies. Recently, scheduling techniques to reduce power consumption of I/O devices in real-time systems have emerged. In this paper, we propose an online task scheduling algorithm, Slack Utilization for Reduced Energy (SURE), which utilizes slack in periodic task …

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A Literature Review On Learner Control Strategies In Software Tutoring Systems, Xin Li, Leen-Kiat Soh Jan 2003

A Literature Review On Learner Control Strategies In Software Tutoring Systems, Xin Li, Leen-Kiat Soh

CSE Technical Reports

This paper is a comprehensive research review on the learner control strategies in software tutoring systems. With the application of more computer techniques in education and the involvement of more adults in software tutoring systems, the learner control strategy has become more appreciated than tutor control or program control. In this paper, the efficiency and necessity of learner control in software tutoring systems is discussed through the description of learning mechanism. Some typical applications of learner control strategies in software tutoring systems are presented. The available learner control strategies are classified from two perspectives: educational theory, and software mechanism. Finally, …

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On Generalized Multiple-Instance Learning, Stephen Scott, Jun Zhang, Joshua Brown Jan 2003

On Generalized Multiple-Instance Learning, Stephen Scott, Jun Zhang, Joshua Brown

CSE Technical Reports

We describe a generalization of the multiple-instance learning model in which a bag’s label is not based on a single instance’s proximity to a single target point. Rather, a bag is positive if and only if it contains a collection of instances, each near one of a set of target points. We list potential applications of this model (robot vision, content-based image retrieval, protein sequence identification, and drug discovery) and describe target concepts for these applications that cannot be represented in the conventional multiple-instance learning model. We then adapt a learning-theoretic algorithm for learning in this model and present empirical …

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Teaching A Multiagent Systems Class With Game Days: Designs And Lessons Learned, Leen-Kiat Soh Jan 2003

Teaching A Multiagent Systems Class With Game Days: Designs And Lessons Learned, Leen-Kiat Soh

CSE Technical Reports

In the Fall semester of 2002, I introduced and taught a class in Multiagent Systems. The class was aimed for seniors (with special permission) and graduate students in Computer Science, covering some breadth and depth of issues in multiagent systems. One of the requirements was participation in four Game Days. On each Game Day, student teams competed against each other in games related to issues such as auction, task allocation, coalition formation, and negotiation. This article documents my designs of and lessons learned from these Game Days. The Game Days were very successful. Through role-playing, the students were motivated and …

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Learning Monotone Dnf Using Spp Teaching Assistant, N. V. Vinodchandran Jan 2003

Learning Monotone Dnf Using Spp Teaching Assistant, N. V. Vinodchandran

CSE Technical Reports

In this paper we prove a new upper bound on learning monotone DNF formulae in an exact learning model called the teaching assistant model. This model, introduced in one of our earlier works, uses teaching assistant classes for classifying the complexity of learning problems. Teaching assistant classes are a learning-theoretic analog of complexity classes. We show that monotone DNF are learnable using a teaching assistant in the class SPP. On the other hand, concept classes such as k-CNF or Boolean circuits are not learnable using an SPP teaching assistant unless Np SPP. We also observe that the recent SPP algorithm …

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Oligothiophenes And Synthesis Thereof, Andrzej Rajca Jan 2003

Oligothiophenes And Synthesis Thereof, Andrzej Rajca

Chemistry Department: Faculty Publications

Novel oligothiophenes and intermediates therefor are disclosed together with a process for synthesizing them. The oligothiophenes are in the form of a helix which contains five-membered rings unsaturated heterocycles that are cross-conjugated and annelated into a helix.

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A Cnf Analogue To Strengthening, Sean Weaver Jan 2003

A Cnf Analogue To Strengthening, Sean Weaver

Morehead Electronic Journal of Applicable Mathematics Archives

No abstract provided.

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Conservation And Restoration Of Pine Forest Genetic Resources In México, C. Sáenz-Romero, Amy E. Snively, R. Lindig-Cisneros Jan 2003

Conservation And Restoration Of Pine Forest Genetic Resources In México, C. Sáenz-Romero, Amy E. Snively, R. Lindig-Cisneros

Student Published Works

Deforestation rates in México are about 670,000 ha/year. This threatens the richness of forest genetic resources in México, causing the disappearance of locally adapted populations and rare and endangered pine species. México is one of the six megadiverse countries in the world, with half of the world’s Pinus species. Pinus is one of the most economically and ecologically important forest genera in México. We suggest that delineation of seed zones and the establishment of a network of Forest Genetic Resource Conservation Units (FGRCUs), linked with forest management and ecological restoration programs will protect this valuable resource. We estimate that FGRCUs …

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Holocene Paleoflood Hydrology Of The Lower Deschutes River, Oregon, Kurt J. Hosman, Lisa L. Ely, Jim E. O'Connor Jan 2003

Holocene Paleoflood Hydrology Of The Lower Deschutes River, Oregon, Kurt J. Hosman, Lisa L. Ely, Jim E. O'Connor

Student Published Works

Flood deposits at four sites along the lower Deschutes River, Oregon, were analyzed to determine magnitude and frequency of late Holocene flooding. Deposit stratigraphy was combined with hydraulic modeling at two sites to determine ranges of likely discharges for individual deposits. Combining these results with gaged flood data provides improved flood frequency estimates at the Axford site. The completeness and age spans of preserved flood chronologies differed among the four sites, but results were consistent for the largest floods of the last 5000 years. Single floods exceeded 2860-3800 mVs -4600 cal yr BP, 1060-1810 mVs -1300 cal yr BP, and …

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Irreducible Polynomials Over Gf(2) With Three Prescribed Coefficients, Robert W. Fitzgerald, Joseph L. Yucas Jan 2003

Irreducible Polynomials Over Gf(2) With Three Prescribed Coefficients, Robert W. Fitzgerald, Joseph L. Yucas

Articles and Preprints

For an odd positive integer n, we determine formulas for the number of irreducible polynomials of degree n over GF(2) in which the coefficients of xn-1, xn-2 and xn-3 are specified in advance. Formulas for the number of elements in GF(2n) with the first three traces specified are also given.

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Tr-2003001: States Of Knowledge And Group Action, Rohit Parikh Jan 2003

Tr-2003001: States Of Knowledge And Group Action, Rohit Parikh

Computer Science Technical Reports

No abstract provided.

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Tr-2003008: Learning And Applying Temporal Patterns Through Experience, Esther Lock Jan 2003

Tr-2003008: Learning And Applying Temporal Patterns Through Experience, Esther Lock

Computer Science Technical Reports

No abstract provided.

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Tr-2003005: Lambek Calculus Is Np-Complete, Mati Pentus Jan 2003

Tr-2003005: Lambek Calculus Is Np-Complete, Mati Pentus

Computer Science Technical Reports

No abstract provided.

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Tr-2003006: Rijndael For Algebraists: An Expanded Version Of Lenstra's Manuscript, Hannes Moritz, Wei Zhu Jan 2003

Tr-2003006: Rijndael For Algebraists: An Expanded Version Of Lenstra's Manuscript, Hannes Moritz, Wei Zhu

Computer Science Technical Reports

No abstract provided.

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Tr-2003014: A High-Performance Abstract Machine For Prolog And Its Extensions, Neng-Fa Zhou Jan 2003

Tr-2003014: A High-Performance Abstract Machine For Prolog And Its Extensions, Neng-Fa Zhou

Computer Science Technical Reports

No abstract provided.

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Tr-2003010: A Semantic Proof Of The Realizability Of Modal Logic In The Logic Of Proofs, Melvin Fitting Jan 2003

Tr-2003010: A Semantic Proof Of The Realizability Of Modal Logic In The Logic Of Proofs, Melvin Fitting

Computer Science Technical Reports

No abstract provided.

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Tr-2003009: A Hierarchical Projection Pursuit Clustering Algorithm, Jayson E. Rome, Alexei D. Miasnikov, Robert M. Haralick Jan 2003

Tr-2003009: A Hierarchical Projection Pursuit Clustering Algorithm, Jayson E. Rome, Alexei D. Miasnikov, Robert M. Haralick

Computer Science Technical Reports

No abstract provided.

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Tr-2003015: Two Counterexamples In The Logic Of Dynamic Topological Systems, Sergey Slavnov Jan 2003

Tr-2003015: Two Counterexamples In The Logic Of Dynamic Topological Systems, Sergey Slavnov

Computer Science Technical Reports

No abstract provided.

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2003 Chesapeake Bay Bridge Tunnel Station Tide Prediction Calendars, Virginia Institute Of Marine Science, David A. Evans Jan 2003

2003 Chesapeake Bay Bridge Tunnel Station Tide Prediction Calendars, Virginia Institute Of Marine Science, David A. Evans

Miscellaneous

These calendars are produced monthly using David Evans' Tidecal.

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Sizes And Shapes Of 10-Ma Distal Fall Pyroclasts In The Ogallala Ggroup, Nebraska, William I. Rose, C. M. Riley, S. Dartevelle Jan 2003

Sizes And Shapes Of 10-Ma Distal Fall Pyroclasts In The Ogallala Ggroup, Nebraska, William I. Rose, C. M. Riley, S. Dartevelle

Department of Geological and Mining Engineering and Sciences Publications

Size distributions of distal ashfall particles from correlated 10-Ma layers in Nebraska, measured using laser diffraction methods, are lognormal with mode diameters of ∼90 mm. This ashfall is ∼100% bubble-wall shards of rhyolite glass and apparently represents a distal ashfall from an eruption 1400 km away. Measured terminal velocities of these ash particles are 0.2–18 cm/s, consistent with Stokes Law settling of spherical particles with diameters of 9–50 mm. Surface area of the ash particles, measured with gas adsorption, is 20–30 times the surface area of equivalent Stokes spheres. These results highlight the effects of shape and atmospheric drag in …

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Quantitative Shape Measurements Of Distal Volcanic Ash, William I. Rose, Colleen M. Riley, Gregg J. Bluth Jan 2003

Quantitative Shape Measurements Of Distal Volcanic Ash, William I. Rose, Colleen M. Riley, Gregg J. Bluth

Department of Geological and Mining Engineering and Sciences Publications

Large-scale volcanic eruptions produce fine ash (< 200 μm) which has a long atmospheric residence time (1 hour or more) and can be transported great distances from the volcanic source, thus, becoming a hazard to aircraft and public health. Ash particles have irregular shapes, so data on particle shape, size, and terminal velocities are needed to understand how the irregular-shaped particles affect transport processes and radiative transfer measurements. In this study, a methodology was developed to characterize particle shapes, sizes , and terminal velocities for three ash samples of different compositions. The shape and size of 2,500 particles from 1) distal fallout (~100 km) of the October 14, 1974 Fuego eruption (basaltic), 2) the secondary maxima (~250 km) of the August 18, 1992 Spurr eruption (andesitic), and 3) the Miocene Ash Hollow member, Nebraska (rhyolitic) were measured using image analysis techniques. Samples were sorted into 10 to 19 terminal velocity groups (0.6-59.0 cm/s) using an air elutriation device. Grain size distributions for the samples were measured using laser diffraction. Aspect ratio, feret diameter, and perimeter measurements were found to be the most useful descriptors of how particle shape affects terminal velocity. These measurement values show particle shape differs greatly from a sphere (commonly used in models and algorithms). The diameters of ash particles were 10-120% larger than ideal spheres at the same terminal velocity, indicating that irregular particle shape greatly increases drag. Gas-adsorption derived surface areas are 1 to 2 orders of magnitude higher than calculated surface areas based on measured dimensions and simple geometry, indicating that particle shapes are highly irregular. Correction factors for surface area were derived from the ash sample measurements so that surface areas calculated by assuming spherical particle shapes can be corrected to reflect more realistic values.

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Retrieval Of Mass And Sizes Of Particles In Sandstorms Using Two Modis Ir Bands: A Case Study Of April 7 2001 Sandstorm In China, Yingxin Gu, William I. Rose, Gregg J. Bluth Jan 2003

Retrieval Of Mass And Sizes Of Particles In Sandstorms Using Two Modis Ir Bands: A Case Study Of April 7 2001 Sandstorm In China, Yingxin Gu, William I. Rose, Gregg J. Bluth

Department of Geological and Mining Engineering and Sciences Publications

A thermal infrared remote sensing retrieval method developed by Wen and Rose [1994], which retrieves particle sizes, optical depth, and total masses of silicate particles in the volcanic cloud, was applied to an April 07, 2001 sandstorm over northern China, using MODIS. Results indicate that the area of the dust cloud observed was 1.34 million km2, the mean particle radius of the dust was 1.44 μm, and the mean optical depth at 11 μm was 0.79. The mean burden of dust was approximately 4.8 tons/km2 and the main portion of the dust storm on April 07, 2001 contained 6.5 million …

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Numerical And Granulometric Approaches To Geophysical Granular Flows , Sébastien Dartevelle Jan 2003

Numerical And Granulometric Approaches To Geophysical Granular Flows , Sébastien Dartevelle

Dissertations, Master's Theses and Master's Reports - Open

Volcanic ash clouds can be fed by an upward-directed eruption column (Plinian column) or by elutriation from extensive pyroclastic-flows (coignimbrite cloud). For large-scale eruptions, there is considerable uncertainty about which mechanism is dominant. Here we analyze in a novel way a comprehensive grainsize database for pyroclastic deposits. We demonstrate that the Mount Pinatubo climactic eruption deposits were substantially derived from coignimbrite clouds, and not only by a Plinian cloud as generally thought. Coignimbrite ash-fall deposits are much richer in breathable <10 m ash (5–25 wt%) than pure Plinian ash at most distances from the source volcano. We also show that coignimbrite ash clouds, as at Pinatubo, are expected to be more water rich than Plinian clouds, leading to removal of more HCl prior to stratospheric injection, thereby reducing their atmospheric impact.

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