Physical Sciences and Mathematics Commons^™

Pulsar Studies Of Tiny-Scale Structure In The Neutral Ism, Joel M. Weisberg, S. Stanimirovi´C

Physics and Astronomy Faculty Work

We describe the use of pulsars to study small-scale neutral structure in the interstellar medium (ISM). Because pulsars are high velocity objects, the pulsarEarth line of sight sweeps rapidly across the ISM. Multiepoch measurements of pulsar interstellar spectral line spectra therefore probe ISM structures on AU scales. We review pulsar measurements of small scale structure in HI and OH and compare these results with those obtained through other techniques.

A New Cryptographic Scheme For Securing Dynamic Conferences In Data Networks, Sarang Deshpande, Ajay Todimala, Ravi K Balachandran, Byrav Ramamurthy, Xukai Zou, N. V. Vinodchandran

School of Computing: Conference and Workshop Papers

Dynamic conferencing refers to a scenario wherein any subset of users in a universe of users form a conference for sharing confidential information among themselves. The key distribution (KD) problem in dynamic conferencing is to compute a shared secret key for such a dynamically formed conference. In literature, the KD schemes for dynamic conferencing either are computationally unscalable or require communication among users, which is undesirable. The extended symmetric polynomial based dynamic conferencing scheme (ESPDCS) is one such KD scheme which has a high computational complexity that is universe size dependent. In this paper we present an enhancement to the …

Router And Firewall Redundancy With Openbsd And Carp, Garhan Attebury, Byrav Ramamurthy

School of Computing: Conference and Workshop Papers

As more reliance is placed on computing and networking systems, the need for redundancy increases. The Common Address Redundancy Protocol (CARP) protocol and OpenBSD’s pfsync utility provide a means by which to implement redundant routers and firewalls. This paper details how CARP and pfsync work together to provide this redundancy and explores the performance one can expect from the open source solutions. Two experiments were run: one showing the relationship between firewall state creation and state synchronization traffic and the other showing how TCP sessions are transparently maintained in the event of a router failure. Discussion of these simulations along …

Autonomous Clustering-Based Heterogeneous Waveband Switching In Wdm Networks, Mengke Li, Byrav Ramamurthy

School of Computing: Conference and Workshop Papers

Employing waveband switching (WBS) in WDM networks can reduce the network operational cost and the call blocking probability. However, upgrading the existing optical switching architecture requires time and money. It is expected that a heterogeneous waveband switching (HeteroWBS) architecture would be desirable, where some nodes can support WBS functions and some cannot. We study the performance of HeteroWBS networks in terms of call blocking probability and cost savings under dynamic traffic requests. We propose an autonomous clustering-based HeteroWBS (AS-HeteroWBS) architecture to clusters the network into multiple autonomous systems (ASs). An AS may contain some specific nodes that provide WBS functions …

Integrated Intermediate Waveband And Wavelength Switching For Optical Wdm Mesh Networks, Mengke Li, Byrav Ramamurthy

School of Computing: Conference and Workshop Papers

As wavelength-division multiplexing (WDM) evolves towards practical applications in optical transport networks, waveband switching (WBS) has been introduced to cut down the operational costs and to reduce the complexities and sizes of network components, e.g., optical cross-connects (OXCs). This paper considers the routing, wavelength assignment and waveband assignment (RWWBA) problem in a WDM network supporting mixed waveband and wavelength switching. First, the techniques supporting waveband switching are studied, where a node architecture enabling mixed waveband and wavelength switching is proposed. Second, to solve the RWWBA problem with reduced switching costs and improved network throughput, the cost savings and call blocking …

A Survey Of Security Issues In Wireless Sensor Networks, Yong Wang, Garhan Attebury, Byrav Ramamurthy

School of Computing: Faculty Publications

Wireless Sensor Networks (WSNs) are used in many applications in military, ecological, and health-related areas. These applications often include the monitoring of sensitive information such as enemy movement on the battlefield or the location of personnel in a building. Security is therefore important in WSNs. However, WSNs suffer from many constraints, including low computation capability, small memory, limited energy resources, susceptibility to physical capture, and the use of insecure wireless communication channels. These constraints make security in WSNs a challenge. In this article we present a survey of security issues in WSNs. First we outline the constraints, security requirements, and …

The Performance Of Elliptic Curve Based Group Diffie-Hellman Protocols For Secure Group Communication Over Ad Hoc Networks, Yong Wang, Byrav Ramamurthy, Xukai Zou

School of Computing: Conference and Workshop Papers

The security of the two party Diffie-Hellman key exchange protocol is currently based on the discrete logarithm problem (DLP). However, it can also be built upon the elliptic curve discrete logarithm problem (ECDLP). Most proposed secure group communication schemes employ the DLP-based Diffie-Hellman protocol. This paper proposes the ECDLP-based Diffie-Hellman protocols for secure group communication and evaluates their performance on wireless ad hoc networks. The proposed schemes are compared at the same security level with DLP-based group protocols under different channel conditions. Our experiments and analysis show that the Tree-based Group Elliptic Curve Diffie-Hellman (TGECDH) protocol is the best in …

Eraid: Conserving Energy In High Performance Raid Systems With Conventional Disks, Dong Li, Jun Wang

School of Computing: Technical Reports

Recently energy consumption becomes an ever critical concern for both low-end and high-end storage server and data centers. A majority of existing energy conservation solutions resort to multi-speed disks. However, current server systems are still built with conventional disks.
In this paper, we propose an energy saving policy, eRAID, for conventional disk based RAID-1 systems. eRAID saves energy by spinning down partial or entire mirror disk group with predictable performance degradation. The heart work of eRAID is to develop an accurate dynamic performance control (including disk power management) scheme. To guarantee service quality, the dynamic performance control works for two …

Helping End-User Programmers “Engineer” Dependable Software, Gregg Rothermel

School of Computing: Conference and Workshop Papers

Not long ago, most software was written by professional programmers, who could be presumed to have an interest in software engineering methodologies and in tools and techniques for improving software dependability. Today, however, a great deal of software is written not by professionals but by end-users, who create applications such as multimedia simulations, dynamic web pages, and spreadsheets. Applications such as these are often used to guide important decisions or aid in important tasks, and it is important that they be sufficiently dependable, but evidence shows that they frequently are not. For example, studies have shown that a large percentage …

Spatio-Temporal Characteristics Of Point And Field Sources In Wireless Sensor Networks, Mehmet C. Vuran, Ӧzgür B. Akan

School of Computing: Conference and Workshop Papers

Wireless Sensor Networks (WSN) are comprised of densely deployed sensor nodes collaboratively observing and communicating extracted information about a physical phenomenon. Dense deployment of sensor nodes makes the sensor observations highly correlated in the space domain. In addition, consecutive samples obtained by a sensor node are also temporally correlated for the applications involving the observation of the variation of a physical phenomenon. Based on the physical characteristics and dispersion pattern over the area, the phenomenon to be observed can be modeled as point source or field source. Clearly, understanding the spatio-temporal correlation characteristics of the point and field sources brings …

A Cross-Layer Protocol For Wireless Sensor Networks, Ian F. Akyildiz, Mehmet C. Vuran, Ӧzgür B. Akan

School of Computing: Conference and Workshop Papers

Severe energy constraints of battery-powered sensor nodes necessitate energy-efficient communication protocols in order to fulfill application objectives of wireless sensor networks (WSN). However, the vast majority of the existing solutions are based on classical layered protocols approach. It is much more resource-efficient to have a unified scheme which melts common protocol layer functionalities into a cross-layer module for resource-constrained sensor nodes. To the best of our knowledge, to date, there is no unified cross-layer communication protocol for efficient and reliable event communication which considers transport, routing, medium access functionalities with physical layer (wireless channel) effects for WSNs.
In this paper, …

Cross-Layer Analysis Of Error Control In Wireless Sensor Networks, Mehmet C. Vuran, Ian F. Akyildiz

School of Computing: Conference and Workshop Papers

Severe energy constraints and hence the low power communication requirements amplify the significance of the energy efficient and preferably cross-layer error control mechanisms in Wireless Sensor Networks (WSN). In this paper, a crosslayer methodology for the analysis of error control schemes in WSNs is presented such that the effects of multi-hop routing and the broadcast nature of the wireless channel are investigated. More specifically, the cross-layer effects of routing, medium access and physical layers are considered. This analysis enables a comprehensive comparison of forward error correction (FEC) and automatic repeat request (ARQ) in WSNs.
FEC schemes improve the error resiliency …

A Constraint-Based Approach To Solving Minesweeper, Ken Bayer, Josh Snyder, Berthe Y. Choueiry

School of Computing: Conference and Workshop Papers

·Motivate the students for the study of Constraint Processing (CP). Minesweeper is perfect to this end because it allows us to illustrate the use of CP algorithms in a familiar context and show how they operate.

·Understand and demystify humans’ fascination with puzzles.

·Discourage graduate students from losing too much time playing the game by making a program that plays the game for them.

Spatial Distributions Of Perchloroethylene Reactive Transport Parameters In The Borden Aquifer, Richelle M. Allen-King, Dana Divine, Michel J. L. Robin, J. Richard Alldredge, David R. Gaylord

Conservation and Survey Division: Faculty and Staff Publications

We determined the descriptive statistical and spatial geostatistical properties of the perchloroethene ln K_d and the ln k of a 1.5 m thick by 10 m horizontal transect of the Borden aquifer near the location of the Stanford-Waterloo (SW) tracer experiment. The ln K_d distribution is not normal and is right skewed because of a few high values that occur localized in two regions of the transect. In contrast, the ln k data can be characterized by a normal distribution. A linear regression of ln K_d on ln k yields a statistically significant positive correlation, also shown …

Erratum: Dynamics Of Filament Formation In A Kerr Medium [Phys Rev. A 71, 063811 (2005)], Martin Centurion, Ye Pu, Mankei Tsang, Demetri Psaltis

Martin Centurion Publications

We have found an error in this paper -- [Phys Rev. A 71, 063811 (2005)]. In our calculation of the intensity threshold for breakdown in CS₂ we erroneously used the ionization energy of molecular CS₂ (10.08 eV). The correct value should be 3.3 eV, the band gap energy of liquid CS₂ . Using the band gap energy, nonlinear absorption will be a three-photon process, and the calculated breakdown threshold becomes 8.5 × 10¹¹ W/cm² (as opposed to the value of 2×10¹³ W/cm² reported previously). Multiphoton absorption and plasma defocusing could then become significant …

Determination Of Diphacinone Residues In Hawaiian Invertebrates, Thomas M. Primus, Dennis J. Kohler, John J. Johnston

United States Department of Agriculture Wildlife Services: Staff Publications

A reversed-phase ion-pair liquid chromatographic analysis combined with a solid-phase extraction clean-up method is used to assess the quantity of diphacinone residue found in invertebrates. Three invertebrate species are exposed to commercially available diphacinone-fortified bait used for rat control. The invertebrate samples are collected, frozen, and shipped to the laboratory. The samples are homogenized after cryogenic freezing. A portion of the homogenized samples are extracted with acidified chloroform–acetone, followed by cleanup with a silica solid-phase extraction column. Diphacinone is detected by UV absorption at 325 nm after separation by the chromatographic system. The method limit of detection (MLOD) for snail …

Alpersite (Mg,Cu)So4•7h2O, A New Mineral Of The Melanterite Group, And Cuprian Pentahydrite: Their Occurrence Within Mine Waste, Ronald C. Peterson, Jane M. Hammarstrom, Robert R. Seal Ii

United States Geological Survey: Staff Publications

Alpersite, Mg_0.58 Cu_0.37 Zn_0.02 Mn_0.02 Fe_0.01SO₄ •7H₂ O, a new mineral species with direct relevance to reactions in mine waste, occurs in a mineralogically zoned assemblage in sheltered areas at the abandoned Big Mike mine in central Nevada at a relative humidity of 65% and T = 4 °C. Blue alpersite, which is isostructural with melanterite (FeSO₄ •7H₂ O), is overlain by a light blue to white layer dominated by pickeringite, alunogen, and epsomite. X-ray diffraction data (MoKα radiation) from a single crystal of alpersite were refined in P2_{1 …}

A Method For Mapping Corn Using The Us Geological Survey 1992 National Land Cover Dataset, S. K. Maxwell, J. R. Nuckols, M. H. Ward

United States Geological Survey: Staff Publications

Long-term exposure to elevated nitrate levels in community drinking water supplies has been associated with an elevated risk of several cancers including non-Hodgkin’s lymphoma, colon cancer, and bladder cancer. To estimate human exposure to nitrate, specific crop type information is needed as fertilizer application rates vary widely by crop type. Corn requires the highest application of nitrogen fertilizer of crops grown in the Midwest US.We developed a method to refine the US Geological Survey National Land Cover Dataset (NLCD) (including map and original Landsat images) to distinguish corn from other crops. Overall average agreement between the resulting corn and other …

Renewing The Conservation Commitment, Frank W. Davis, Dale D. Goble, J. Michael Scott

United States Geological Survey: Staff Publications

As we write this in early 2005 there are several ESA-related pieces of legislation pending before Congress. Most of the proposed legislation is championed by Republican leaders from western states, who promise to strengthen the use of science or ensure fairer treatment of private landowners. Ir has become a perennial drama on the American political stage: "conservatives" rally to rein in a law that they believe has reached too far and "conservationists" mobilize ro defend the law that they believe offers the best ho pe for protecting biodiversity from relentless economic exploitation. There is much posturing, finger pointing, and, ultimately, …

Breeding Biology And Success Of A Reintroduced Population Of The Critically Endangered Puaiohi (Myadestes Palmeri), Erik J. Tweed, Jeffrey T. Foster, Bethany L. Woodworth, William B. Monahan, Jherime L. Kellerman, Alan Lieberman

United States Geological Survey: Staff Publications

The ultimate success of reintroduction programs for endangered species depends on the ability of reintroduced animals to breed in the wild. We studied the nesting success and breeding biology of a reintroduced population of Puaiohi (Myadestes palmeri) on the island of Kaua‛i, Hawaii. Thirty-four captive-bred Puaiohi were released into the Alaka‛i Swamp in 1999–2001 and monitored using radiotelemetry. Ten females and two males paired with wild and other released birds, including one polygynous trio. From March to September, 31 nests were built. Mean clutch size was 2.0 eggs, daily nest survival was 0.97 ± 0.01 (mean ± SE) …

The Sedimentary Environment Below Earth’S Polar Ice Cap As A Microbial Habitat, David C. Smith, Stephanie Forschner-Dancause, David C. Rowley, Steven D'Hondt

Graduate School of Oceanography Faculty Publications

University of Rhode Island faculty participated in drilling of the polar ice cap to study microbial diversity and adaptation to subsurface life under conditions that may mimic extraterrestrial subsurface conditions.

Implementing Built-In Properties For The Java Programming Language, Alexandre Alves

Master's Projects

The purpose of this project is to improve the programming experience of using the Java language by implementing properties as a built-in facility. In this project, the Java compiler tool, and the Java documentation tool were modified. In addition, a new Java annotation processor that generates Java BeanInfo source files was created. These new features result in a more productive development environment for the Java programming language.

Quantal Density Functional Theory: Wave Function Arbitrariness Of The Noninteracting Fermion Model, Viraht Sahni, Marlina Slamet

Physics Faculty Publications

In quantal density functional theory (Q-DFT), the mapping from either a ground or excited state of the interacting system to one of noninteracting fermions with equivalent density is such that the state of the latter model S system is arbitrary. Thus, in principle, there are an infinite number of local (multiplicative) effective potential energy functions that can reproduce the density of the interacting system. In the present work, we note that there is also an arbitrariness in the wave function of the model fermions when the S system is constructed in an excited state. Different wave functions lead to the …

Learning Languages From Positive Data And A Finite Number Of Queries, Sanjay Jain, Efim Kinber

School of Computer Science & Engineering Faculty Publications

A computational model for learning languages in the limit from full positive data and a bounded number of queries to the teacher (oracle) is introduced and explored. Equivalence, superset, and subset queries are considered (for the latter one we consider also a variant when the learner tests every conjecture, but the number of negative answers is uniformly bounded). If the answer is negative, the teacher may provide a counterexample. We consider several types of counterexamples: arbitrary, least counterexamples, the ones whose size is bounded by the size of positive data seen so far, and no counterexamples. A number of hierarchies …

A Quantitative Method For Iso 17799 Gap Analysis, Bilge Karabacak, Ibrahim Sogukpinar

All Faculty and Staff Scholarship

ISO/IEC 17799:2005 is one of the leading standards of information security. It is the code of practice including 133 controls in 11 different domains. There are a number of tools and software that are used by organizations to check whether they comply with this standard. The task of checking compliance helps organizations to determine their conformity to the controls listed in the standard and deliver useful outputs to the certification process. In this paper, a quantitative survey method is proposed for evaluating ISO 17799 compliance. Our case study has shown that the survey method gives accurate compliance results in a …

Study Of Metals In Leached Soils Of A Municipal Dumpsite In Tampico, Tamaulipas, Mexico: Preliminary Results, P. F. Rodríguez-Espinosa, D. Chazaro Mendoza, J. A. Montes De Oca, G. Sánchez Torres E., Alejandro Fierro-Cabo

School of Earth, Environmental, & Marine Sciences Faculty Publications

The Zapote dumpsite measures 420000 m 2 and is 28 years old; an estimated 2.5 millions tons of waste have accumulated on the site (household waste, clinical waste, commercial waste). The thickness of the waste is 3 to 9 meters. Since operations began, no control regulations have existed on the residues received. The Zapote dumpsite is located within a salt-marsh between a system of channels and river lagoons of brackish water, located in a tropical sedimentary environment in the urban zone of Tampico, Tamaulipas, Mexico. Recently, the Zapote has been closed and work is presently underway in its rehabilitation since …

Improving Community Water Conservation Behaviour In Chachoengsao, Thailand, Kuakul Sathapornvajana, Lynne Cohen, Neil Drew, Julie Ann Pooley

EDU-COM International Conference

The issue of water supply throughout the world is of concern for many reasons. A major factor is water pollution by industry, agriculture and residential sectors. Less than 3% of water is fresh and potable, while the remainder is saline. It is projected that by the year 2025, two-thirds of the world‘s population will encounter moderate to severe water shortages. As a result of unsustainable development over the past decade, Thailand has faced pollution problems as well as the depletion of many natural resources. These problems have impacted the country‘s main rivers (Chaopraya River, Thachine River, and the Bangpakong River), …

A Real-Time Virtual Classroom System With Two-Way Communication For Distance Learning At King Mongkut’S University Of Technology Thonburi, Thailand, Surachai Suksakulchai, Chalathip Chunkul

EDU-COM International Conference

Because of high demands for higher education in the provinces of Thailand, the school of Industrial Education and Technology at KMUTT has started off-campus courses since 2002. However, the major problem of operation is distance. To cope with the problem, a real-time virtual classroom system with two-way communication has been developed. The system has to overcome the bandwidth problem, which is the major struggle of web-based learning in Thailand, and to maintain the two-way communication between instructors and students. To cope with those problems, video streaming and live chat systems are used. The technique is the trade-off between two-way and …

สัมภาษณ์พิเศษ : นายอภิรักษ์ โกษะโยธิน ผู้ว่าราชการกรุงเทพมหานคร นโยบายสิ่งแวดล้อม เพื่อ (ของ) คนกรุงเทพฯ ปี 49

Thai Environment

No abstract provided.

สรุปสถานการณ์สิ่งแวดล้อม ปี 48

Thai Environment

No abstract provided.