Physical Sciences and Mathematics Commons^™

Switching In One Monolayer Of The Ferroelectric Polymer, Vladimir Fridkin, A. Ievlev, K. Verkhovskaya, G. Vizdrik, S. Yudin, Stephen Ducharme

Stephen Ducharme Publications

The switching in one monolayer of ferroelectric vinylidene fluoride-trifluoroethylene copolymer P[VDF-TrFE] is observed. The kinetics of switching is well described by Landau- Khalatnikov (LK) equation.

The paper is devoted to the 75th anniversary of Prof. Lemanov’s birthday.

Investigation Of Ferroelectricity In Newly Synthesized Nitrile Polymer Systems, Matt Poulsen, Stephen Ducharme, Alexander V. Sorokin, Sahadeva Reddy, James M. Takacs, Y. Wen, Jihee Kim, Shireen Adenwalla

Stephen Ducharme Publications

The ferroelectric and piezoelectric properties of newly synthesized polymer systems have been studied. To date PVDF and its copolymers P(VDF-TrFE) have provided the bulk of the knowledge pertaining to ferroelectricity in polymers. Recently, ultrathin ferroelectric films of P(VDF-TrFE) 70:30 have been fabricated using the Langmuir-Blodgett technique [4]. In this study, various new polymers have been synthesized by chemically altering the PVDF structure. This alteration was performed in order to enhance the amphiphilic nature of the polymer and thus improve the LB film quality and control. Various chemical groups have been used to replace the electropositive hydrogen and electronegative fluorine found …

Julian Cecil Stanley Papers, Zach S. Henderson Library, Special Collections

Finding Aids

This collection consists of the research materials of Johns Hopkins professor of psychology, Julian C. Stanley. Materials range from 1950-2005 and include his published reprints, abstracts, reports, letters, and seminar papers. The collection also includes reviews of research materials and articles by prominent psychologists in similar fields.

Find this collection in the University Libraries' catalog.

Matrix Model Superpotentials And Calabi–Yau Spaces: An A-D-E Classification, Carina Curto

Department of Mathematics: Faculty Publications

We use F. Ferrari’s methods relating matrix models to Calabi-Yau spaces in order to explain Intriligator and Wecht’s ADE classification of N = 1 superconformal theories which arise as RG fixed points of N = 1 SQCD theories with adjoints. The connection between matrix models and N = 1 gauge theories can be seen as evidence for the Dijkgraaf–Vafa conjecture. We find that ADE superpotentials in the Intriligator–Wecht classification exactly match matrix model superpotentials obtained from Calabi-Yau’s with corresponding ADE singularities. Moreover, in the additional Ô, Â, Dˆ and Ê cases we find new singular geometries. These ‘hat’ geometries are …

Pseudo-Codewords Of Cycle Codes Via Zeta Functions, Ralf Koetter, Wen-Cheng W. Li, Pascal O. Vontobel, Judy L. Walker

Department of Mathematics: Faculty Publications

Cycle codes are a special case of low- density parity-check (LDPC) codes and as such can be decoded using an iterative message-passing decod- ing algorithm on the associated Tanner graph. The existence of pseudo-codewords is known to cause the decoding algorithm to fail in certain instances. In this paper, we draw a connection between pseudo- codewords of cycle codes and the so-called edge zeta function of the associated normal graph and show how the Newton polyhedron of the zeta function equals the fundamental cone of the code, which plays a crucial role in characterizing the performance of iterative de- coding …

Weak Solutions To The Cauchy Problem Of A Semilinear Wave Equation With Damping And Source Terms, Petronela Radu

Department of Mathematics: Faculty Publications

In this paper we prove local existence of weak solutions for a semilinear wave equation with power-like source and dissipative terms on the entire space ℝⁿ. The main theorem gives an alternative proof of the local in time existence result due to J. Serrin, G. Todorova and E. Vitillaro, and also some extension to their work. In particular, our method shows that sources that are not locally Lipschitz in L² can be controlled without any damping at all. If the semilinearity involving the displacement has a “good” sign, we obtain global existence of solutions.

Do Meteorologists Suppress Thunderstorms? Radar-Derived Statics And The Behavior Of Moist Convection, Matthew D. Parker, Jason C. Knievel

Department of Earth and Atmospheric Sciences: Faculty Publications

Most meteorologists are acquainted with the no- tion of a weather hole—that is, a place that receives less exciting weather than does its surroundings. Exciting weather takes many forms, but when people use the term weather hole, they tend to mean a place that thunderstorms often barely miss, or near which approaching storms often dissipate. For this paper, that is the meaning we adopt.

In our experience, many meteorologists and lay weather enthusiasts genuinely believe that they live in weather holes, and this belief, almost without fail, seems to stem from countless hours spent gazing at displays of radar reflectivity. …

Performance Of Quality Assurance Procedures For An Applied Climate Information System, K. G. Hubbard, S. Goddard, Bill Sorensen, N. Wells, Thomas Osugi

Department of Earth and Atmospheric Sciences: Faculty Publications

Valid data are required to make climate assessments and to make climate-related decisions. The objective of this paper is threefold: to introduce an explicit treatment of Type I and Type II errors in evaluating the performance of quality assurance procedures, to illustrate a quality control approach that allows tailoring to regions and subregions, and to introduce a new spatial regression test. Threshold testing, step change, persistence, and spatial regression were included in a test of three decades of temperature and precipitation data at six weather stations representing different climate regimes. The magnitude of thresholds was addressed in terms of the …

Maternal Yolk Steroids: A Potential Compensatory Mechanism For Red-Winged Blackbirds (Agelaius Phoeniceus) In North Dakota, Rachel M. Bush, Mark E. Clark, Wendy L. Reed, George M. Linz

United States Department of Agriculture Wildlife Services: Staff Publications

Many of the suggested management techniques directed at reducing blackbird breeding populations fail to incorporate the underlying mechanisms regulating populations. Theoretically, removal of individuals from the breeding population should lower the breeding densities and presumably reduce recruitment. However, compensatory responses might occur with decreased breeding densities, but no empirical data are available to test this hypothesis. Much of the underlying compensatory theory is based on differential allocation of resources to reproduction vs. self maintenance at different breeding densities, mainly in the form of depensatory effects of resource limitation on growth and survival. However, as the breeding density in an area …

Evaluation Of Lorsban®-4e Aerially Sprayed On Sunflower Plots For Bird Repellency, George M. Linz, Anthony A. Slowik, Linda B. Penry, Jeffrey Homan

United States Department of Agriculture Wildlife Services: Staff Publications

Ripening sunflower fields in the northern Great Plains provide blackbirds with easily accessible sources of high-energy food. As many growers can attest, blackbirds can be nearly impossible to discourage from foraging in favored fields. To date, no single management method has been especially effective at consistently discouraging blackbirds.

Developing Relative Abundance Techniques (Rats) For Monitoring Rodent Populations, Desely A. Whisson, Richard M. Engeman, Kellie Collins

United States Department of Agriculture Wildlife Services: Staff Publications

Accurate density estimates of rodents are frequently difficult or cost-prohibitive to determine. Thus, a number of techniques (track plates, monitoring blocks, chew cards/sticks, apple slice index, trapping) are often used to index rodent populations. Theoretically, the sensitivity of these indexing techniques could be improved if they applied continuous measurements rather than simple binary measurements (presence/absence). Development of a relative abundance technique that is simple to apply and sensitive to changes in population density is critical for the operational management of rodent pests. In addition to providing a quantitative measure of abundance with statistical parameters, an indexing technique that does not …

Husbandry Of Wild-Caught Greater Sage-Grouse, Paul Oesterle, Robert Mclean, Michael Dunbar, Larry Clark

United States Department of Agriculture Wildlife Services: Staff Publications

This study reports the first successful husbandry and breeding in captivity of wild-caught greater sage-grouse (Ccntroccrcus urophasianus). In October 2003, 2 1 hatch-year greater sage-grouse were trapped in northwestern Nevada and transported to Fort Collins, Colorado. We held grouse in pens at the United States Department of Agriculture's National Wildlife Research Center for 8 months. We offered a varied diet, including native food items such as sagebrush (Arternisia tridentata and A. tripartita) and yarrow (Achilles millefolium). We housed grouse in a large flight pen and allowed to them freerange as one flock. Mortdlity rate was 16.7%. Several of the grouse …

Stability Of The Tranquilizer Drug Propionylpromazine Hydrochloride In Formulated Products, Thomas M. Primus, Bruce A. Kimball, Jerome Hurley, John J. Johnston, Sherm Blom, Peter J. Savarie

United States Department of Agriculture Wildlife Services: Staff Publications

An analytical method to evaluate propionylpromazine hydrochloride (PPZHCl) in tranquilizer formulations was developed using high-performance liquid chromatography (HPLC). During analysis of aged quality-control samples, a previously unreported chromatographic response was observed at a shorter retention time than PPZHCl. Further investigation of formulations stored in trap tap devices at temperatures ranging from 5 to 40 ◦C during field trials at four different locations confirmed the degradation of the active ingredient. Further investigation using HPLC/tandem mass spectrometry revealed two to five degradates, with the major degradates being oxidation products of the active ingredient, PPZHCl. As PPZHCl formulations must be stable when stored …

A Heuristic With Bounded Guarantee To Compute Diverse Paths Under Shared Protection In Wdm Mesh Networks, Ajay Todimala, Byrav Ramamurthy

School of Computing: Conference and Workshop Papers

Establishing a fault-tolerant connection in a network involves computation of diverse working and protection paths. The Shared Risk Link Group (SRLG) [1] concept is used to model several types of failure conditions such as link, node, fiber conduit, etc. In this work we focus on the problem of computing optimal SRLG/link diverse paths under shared protection. Shared protection technique improves network resource utilization by allowing protection paths of multiple connections to share resources. In this work we propose an iterative heuristic for computing SRLG/link diverse paths. We present a method to calculate a quantitative measure that provides a bounded guarantee …

Technical Reports (1999 - 2005)

School of Computing: Technical Reports

Authors of Technical Reports (1999-2005):
Choueiry, Berthe
Elbaum, Sebastian
Goddard, Steve
Henninger, Scott
Jiang, Hong
Rothermel, Gregg
Scott, Stephen
Seth, Sharad
Soh, Leen-Kiat
Variyam, Vinodchandran

An Empirical Study Of Fault Localization For End-User Programmers, Joseph R. Ruthruff, Margaret Burnett, Gregg Rothermel

School of Computing: Conference and Workshop Papers

End users develop more software than any other group of programmers, using software authoring devices such as e-mail filtering editors, by-demonstration macro builders, and spreadsheet environments. Despite this, there has been little research on finding ways to help these programmers with the dependability of their software. We have been addressing this problem in several ways, one of which includes supporting end-user debugging activities through fault localization techniques. This paper presents the results of an empirical study conducted in an end-user programming environment to examine the impact of two separate factors in fault localization techniques that affect technique effectiveness. Our results …

A Controlled Experiment Assessing Test Case Prioritization Techniques Via Mutation Faults, Hyunsook Do, Gregg Rothermel

School of Computing: Conference and Workshop Papers

Regression testing is an important part of software maintenance, but it can also be very expensive. To reduce this expense, software testers may prioritize their test cases so that those that are more important are run earlier in the regression testing process. Previous work has shown that prioritization can improve a test suite’s rate of fault detection, but the assessment of prioritization techniques has been limited to hand-seeded faults, primarily due to the belief that such faults are more realistic than automatically generated (mutation) faults. A recent empirical study, however, suggests that mutation faults can be representative of real faults. …

Helping End-Users “Engineer” Dependable Web Applications, Sebastian Elbaum, Kalyan-Ram Chilakamarri, Bhuvana Gopal, Gregg Rothermel

School of Computing: Conference and Workshop Papers

End-user programmers are increasingly relying on web authoring environments to create web applications. Although often consisting primarily of web pages, such applications are increasingly going further, harnessing the content available on the web through “programs” that query other web applications for information to drive other tasks. Unfortunately, errors can be pervasive in web applications, impacting their dependability. This paper reports the results of an exploratory study of end-user web application developers, performed with the aim of exposing prevalent classes of errors. The results suggest that end-users struggle the most with the identification and manipulation of variables when structuring requests to …

Balancing Exploration And Exploitation: A New Algorithm For Active Machine Learning, Thomas Osugi, Deng Kun, Stephen Scott

School of Computing: Conference and Workshop Papers

Active machine learning algorithms are used when large numbers of unlabeled examples are available and getting labels for them is costly (e.g. requiring consulting a human expert). Many conventional active learning algorithms focus on refining the decision boundary, at the expense of exploring new regions that the current hypothesis misclassifies. We propose a new active learning algorithm that balances such exploration with refining of the decision boundary by dynamically adjusting the probability to explore at each step. Our experimental results demonstrate improved performance on data sets that require extensive exploration while remaining competitive on data sets that do not. Our …

Neighborhood Interchangeability And Dynamic Bundling For Non-Binary Csps, Anagh Lal, Berthe Y. Choueiry, Eugene C. Freuder

School of Computing: Conference and Workshop Papers

1. Interchangeability: An algorithm for computing interchangeability in non-binary CSPs.

2. Dynamic bundling: Integration of the above with backtrack search for solving non-binary CSPs.

3. Experiments demonstrating the benefits of dynamic bundling

·Finding multiple, robust solutions.

·Decreasing computational cost of search.

On Finding Consecutive Test Vectors In A Random Sequence For Energy-Aware Bist Design, Sheng Zhang, Sharad C. Seth, Bhargab B. Bhattacharya

School of Computing: Conference and Workshop Papers

During pseudorandom testing, a significant amount of energy and test application time is wasted for generating and for applying “useless” test vectors that do not contribute to fault dropping. For low-power testing, modification logic/ROM may be used to skip the LFSR states that generate useless test patterns. The overhead of extra logic increases rapidly with the number of such jumps. Since identification of useless patterns strongly depends on the order in which incremental fault simulation is performed, an elegant solution to this problem would be to find a minimum set of segments in the LFSR sequence, where each segment corresponds …

Profiling Deployed Software: Strategic Probe Placement, Madeline Diep, Sebastian Elbaum, Myra B. Cohen

School of Computing: Technical Reports

Profiling deployed software provides valuable insights for quality improvement activities. The probes required for profiling, however, can cause an unacceptable performance overhead for users. In previous work we have shown that significant overhead reduction can be achieved, with limited information loss, through the distribution of probes across deployed instances. However, existing strategies for probe distribution do not account for several relevant factors: acceptable overheads may vary, the distributions to be deployed may be limited, profiled events may have different likelihoods, and the user pool composition may be unknown. This paper evaluates strategies for probe distribution while manipulating these factors through …

Disseminating Usability Design Knowledge Through Ontology-Based Pattern Languages, Scott Henninger, Padmapriya Ashokkumar

School of Computing: Technical Reports

Usability patterns represent knowledge about known ways to design graphical user interfaces that are usable and meet the needs and expectations of users. There is currently a plethora of usability patterns published in books, private repositories and the World-Wide Web. The dominance of pattern discovery efforts has neglected the emerging need to organize the patterns so they can become a proactive resource for developing interfaces. This paper presents an approach using Semantic Web concepts that turns informal patterns into formal representations capable of supporting systematic design methods. Through this method, loosely coupled pattern collections can be turned into strongly coupled …

Real-Time Divisible Load Scheduling For Cluster Computing, Xuan Lin, Ying Lu, Jitender S. Deogun, Steve Goddard

School of Computing: Technical Reports

Cluster Computing has emerged as a new paradigm for solving large-scale problems. To enhance QoS and provide performance guarantees in cluster computing environments, various workload models and real-time scheduling algorithms have been investigated. The divisible load model, propagated by divisible load theory, models computations that can be arbitrarily divided into independent pieces and provides a good approximation of many real-world applications. However, researchers have not yet investigated the problem of providing performance guarantees to divisible load applications. Two contributions are made in this paper: (1) divisible load theory is extended to compute the minimum number of processors required to meet …

Dgkd: Distributed Group Key Distribution With Authentication Capability, Pratima Adusumilli, Xukai Zou, Byrav Ramamurthy

School of Computing: Conference and Workshop Papers

Group key management (GKM} is the most important issue in secure group communication (SCC). The existing GKM protocols fall into three typical classes: centralized group key distribution (CGKD), decentralized group key management (DGKM), and distributed/contributory group key agreement (CGKA). Serious problems remains in these protocols, as they require existence of central trusted entities (such as group controller or subgroup controllers), relaying of messages (by subgroup controllers), or strict member synchronization (JOT multiple round stepwise key agreement), thus suffering from the single point of failure and attack, performance bottleneck, or mis-operations in the situation of transmission delay or network failure. In …

Crtdh: An Efficient Key Agreement Scheme For Secure Group Communications In Wireless Ad Hoc Networks, Ravi K Balachandran, Byrav Ramamurthy, Xukai Zou, N.V. Vinodchandran

School of Computing: Conference and Workshop Papers

As a result of the growing popularity of wireless networks, in particular ad hoc networks, security over such networks has become very important. In this paper, we study the problem of secure group communications (SGC) and key management over ad hoc networks. We identify the key features of any SGC protocol for such networks. We also propose an efficient key agreement scheme for SGC. The scheme solves two important problems that exist in most current SGC schemes: requirement of member serialization and existence of a central entity. Besides this, the protocol also has many highly desirable properties such as contributory …

Same-Destination-Intermediate Grouping Vs. End-To-End Grouping For Waveband Switching In Wdm Mesh Networks, Mengke Li, Wang Yao, Byrav Ramamurthy

School of Computing: Conference and Workshop Papers

We investigate waveband switching (WBS) with different grouping strategies in wavelength-division multiplexing (WDM) mesh networks. End-to-end waveband switching (ETEWBS) and same-destination-intermediate waveband switching (SD-IT-WBS) are analyzed and compared in terms of blocking probability and cost savings. First, an analytical model for ETEWBS is proposed to determine the network blocking probability in a mesh network. For SD-IT-WBS, a simple waveband switching algorithm is presented. An analytical model to determine the network blocking probability is proposed for SD-IT-WBS based on the algorithm. The analytical results are validated by comparing with simulation results. Both results match well and show that ETE-WBS slightly outperforms …

A Novel Cost-Efficient On-Line Intermediate Waveband-Switching Scheme In Wdm Mesh Networks, Mengke Li, Wang Yao, Byrav Ramamurthy

School of Computing: Conference and Workshop Papers

Waveband switching (WBS) is an important technique to save switching and transmission cost in wavelength -division multiplexed (WDM) optical networks. A cost-efficient WBS scheme would enable network carriers to increase the network throughput (revenue) while achieving significant cost savings. We identify the critical factors that determine the WBS network throughput and switching cost and propose a novel intermediate waveband switching (IT-WBS) algorithm, called the minimizing-weighted-cost (MWC) algorithm. The MWC algorithm defines a cost for each candidate route of a call. By selecting the route with the smallest weighted cost, MWC balances between minimizing the call blocking probability and minimizing the …

In Memoriam: John Platt Bradbury (1936–2005), Walter Dean, Sherilyn C. Fritz, Cathy Whitlock, William Watts

Department of Earth and Atmospheric Sciences: Faculty Publications

John Platt Bradbury, a former United States Geological Survey (USGS) geologist, and a long time and much valued editorial board member for the Journal of Paleolimnology, died of cancer (abdominal mesothelioma) on August 15, 2005, in the log home that he and his wife Vera Markgraf built in the mountains near Monte Vista, Colorado. Platt’s interest in paleolimnology developed during his graduate school years at the University of New Mexico, working with Roger Anderson and Walt Dean. He received his Ph.D. in 1967. He went on to do post-doctoral research at Yale University under G. Evelyn Hutchinson and then …

High-Resolution Ocean Color Remote Sensing Of Benthic Habitats: A Case Study At The Roatan Island, Honduras, Deepak R. Mishra, Sunil G. Narumalani, Donald Rundquist, Merlin P. Lawson

Department of Earth and Atmospheric Sciences: Faculty Publications

Natural resource managers clamor for detailed reef habitat maps for monitoring smaller scale disturbances in reef communities. Coastal ocean color remote sensing techniques permit benthic habitats to be explored with higher resolution than ever before. The objective of this research was to develop an accurate benthic habitat map for an area off the northwest coast of Roatan Island, Honduras, using high-resolution multispectral IKONOS data. Atmospheric (Rayleigh and aerosol path radiance) and water column corrections (water depth and water column attenuation) were applied to the imagery, making it a robust method for mapping benthic habitats. Water depth for each pixel was …