Physical Sciences and Mathematics Commons^™

High-Resolution, Wide-Field Imaging Of The Galactic Center Region At 330 Mhz, Michael E. Nord, T. Joseph W. Lazio, Namir E. Kassim, Scott D. Hyman, Ted W. La Rosa, Crystal L. Brogan, Nebojsa Duric

Faculty Articles

We present a wide-field, subarcminute-resolution VLA image of the Galactic center region at 330 MHz. With a resolution of ~7'' × 12'' and an rms noise of 1.6 mJy beam^-1, this image represents a significant increase in resolution and sensitivity over the previously published VLA image at this frequency. The improved sensitivity has more than tripled the census of small-diameter sources in the region, has resulted in the detection of two new nonthermal filaments (NTFs), 18 NTF candidates, and 30 pulsar candidates, reveals previously known extended sources in greater detail, and has resulted in the first detection of …

Modeling And Simulation Of Photonic Crystal Fibers Using Finite Difference Frequency Domain Method, Md. Khalid Ikram

Electrical & Computer Engineering Theses & Dissertations

Photonic crystal fibers (PCFs) allow guiding light in low-index core. These fibers exhibit properties such as single-mode operation in broad wavelength region. The mode shape and group velocity dispersion can be controlled by designing the microstructures of the cladding. In order to study these properties, a fast, efficient, and highly accurate numerical modeling method is required.

A full-vectorial finite-difference frequency-domain (FDFD) method is implemented. The modal properties of conventional step index fiber and index-guiding PCF are analyzed using this modeling technique. Compared to plane wave expansion and biorthogonal basis methods, FDFD is found to be simple, reliable, and efficient. PCFs …

Hierarchical Hybrid Multicast An End System Multicast Algorithm Approach, Guillermo Loaisiga

Electrical & Computer Engineering Theses & Dissertations

Due to the rapid development in the computer and communication technologies, the Internet is experiencing an increasing demand of high-speed, real-time distributed applications, such as live streaming multimedia, videoconferencing, distributed simulations, and multiparty games. Multicast is an efficient transmission mechanism to support these applications. Historically, IP Multicast (IPM) has provided multicast support with well-known benefits, especially in bandwidth savings. However, it has experienced little deployment due to economic and architectural limitations.

Overlay multicast holds promise for the implementation of large scale Internet multicast services. An overlay network is a virtual topology constructed on top of the Internet infrastructure. This concept …

Measurement Of The Tt̅ Production Cross Section In Pp̅ Collisions At √S =1.96 Tev Using Dilepton Events, Darin Acosta, Kenneth A. Bloom, Collider Detector At Fermilab Collaboration

Kenneth Bloom Publications

We report a measurement of the tt̅ production cross section using dilepton events with jets and missing transverse energy in pp̅ collisions at a center-of-mass energy of 1.96 TeV. Using a 197±12 pb^-1 data sample recorded by the upgraded Collider Detector at Fermilab, we use two complementary techniques to select candidate events. We compare the number of observed events and selected kinematical distributions with the predictions of the standard model and find good agreement. The combined result of the two techniques yields a tt̅ production cross section of 7.0_-2.1^+2.4 (stat) _-1.1^+1.6 (syst)±0.4(lum) pb.

Photometry Of Type Ii Cepheids. I. The Long-Period Stars, Edward G. Schmidt, Dale Johnston, Shawn Langan, Kevin M. Lee

Department of Physics and Astronomy: Faculty Publications

We present 1256 new photometric observations of 36 Cepheids with periods longer than 8 days. The majority are likely type II Cepheids, but we have included about a dozen classical Cepheids for comparison purposes, a few stars of uncertain type, and one putative RV Tauri star. We discuss the appearance of the light curves, the Fourier parameters, and the light-curve stability in terms of differentiation between type I and type II Cepheids. Although we encounter the same difficulties as previous investigators in using these parameters for this purpose, we are able to identify some stars of particular interest, including several …

Distal Placement Of An End-To-Side Bypass Graft Anastomosis A 3-D Computational Study, John Robert Di Cicco

Mechanical & Aerospace Engineering Theses & Dissertations

A three-dimensional computational fluid dynamics study of blood flow through stenotic arteries has been conducted. Flow phenomena, such as separation regions and turbulence, can be found distal to an arterial stenosis. Frequently, a bypass graft using an end-to-side technique is attached to a stenotic artery to restore adequate blood flow. However, a significant percentage of these grafts fail after thirty postoperative days due to intimal hyperplasia development around the distal anastomosis. Moreover, aberrant wall shear rates have been implicated as a factor in the development of intimal hyperplasia. Thus, the present study examines whether placement of the distal end of …

Bacterial Degradation Of Disinfection By-Products In Drinking Water, Laura Inga Fauntleroy

Chemistry & Biochemistry Theses & Dissertations

Chlorine became a major disinfectant for the removal of microbial contaminants in 1914. Current water chlorination procedures yield halogenated disinfection byproducts (DBPs), such as haloalkanes and haloacetic acids (HAAs), due to the reaction of chlorine with naturally occurring organic compounds. Various water utilities have observed decreased HAAs levels in maximum residence time locations (MRTLs), where they were expected to be higher. These MRTLs have low free chlorine residual and high heterotrophic bacteria plate counts. Xanthobacter autotrophicus, GJ-10, is a bacterium that has been shown to contain dehalogenase enzymes and, therefore, can biodegrade HAAs. A number of water-system bacteria were …

Blocking Reduction Strategies In Hierarchical Text Classification, Ee Peng Lim, Aixin Sun, Wee-Keong Ng, Jaideep Srivastava

Research Collection School Of Computing and Information Systems

One common approach in hierarchical text classification involves associating classifiers with nodes in the category tree and classifying text documents in a top-down manner. Classification methods using this top-down approach can scale well and cope with changes to the category trees. However, all these methods suffer from blocking which refers to documents wrongly rejected by the classifiers at higher-levels and cannot be passed to the classifiers at lower-levels. We propose a classifier-centric performance measure known as blocking factor to determine the extent of the blocking. Three methods are proposed to address the blocking problem, namely, threshold reduction, restricted voting, and …

Compliant Encryption Of Jpeg2000 Codestreams, Yongdong Wu, Robert H. Deng

Research Collection School Of Computing and Information Systems

This paper presents a compliant encryption method for JPEG 2000 codestreams such that the encryption process does not introduce superfluous JPEG2000 markers in the protected codestream, i.e., the protected codestream preserves the syntax of the original codestream. The proposed encryption method works with any standard ciphers, incurs no storage overhead, introduces negligible computational cost and maintains all the desirable properties of the original JPEG 2000 codestream such as error resilience and scalability.

Flexible Verification Of Mpeg-4 Stream In Peer-To-Peer Cdn, Tieyan Li, Yongdong Wu, Di Ma, Robert H. Deng

Research Collection School Of Computing and Information Systems

The current packet based stream authentication schemes provide effective and efficient authentication over a group of packets transmitted on erasure channels. However, by fixing the packets in transmission, any packet manipulation will cause authentication failure. In p2p content delivery network where a proxy-in-the-middle is able to store, forward, transcode and transform the stream, previous schemes are simply unapplicable. To address the problem, we propose a flexible verification scheme that relies on special stream formats (i.e. Unequal Loss Protection ULP scheme [7]). We apply the so called Unequal Loss Verification ULV scheme into MPEG-4 framework. The encoding, packing, amortizing and verifying …

Dynamic Access Control For Multi-Privileged Group Communications, Di Ma, Robert H. Deng, Yongdong Wu, Tieyan Li

Research Collection School Of Computing and Information Systems

Recently, there is an increase in the number of group communication applications which support multiple service groups of different access privileges. Traditional access control schemes for group applications assume that all the group members have the same access privilege and mostly focus on how to reduce rekeying messages upon user joining and leaving. Relatively little research effort has been spent to address security issues for group communications supporting multiple access privileges. In this paper, we propose a dynamic access control scheme for group communications which support multiple service groups with different access privileges. Our scheme allows dynamic formation of service …

Design And Analysis Of A Cooperative Medium Access Scheme For Wireless Mesh Networks, Arup Acharya, Archan Misra, Sorav Bansal

Research Collection School Of Computing and Information Systems

This paper presents the detailed design and performance analysis of MACA-P, a RTS/CTS based MAC protocol, that enables simultaneous transmissions in wireless mesh networks. The IEEE 802.11 DCF MAC prohibits any parallel transmission in the neighborhood of either a sender or a receiver (of an ongoing transmission). MACA-P is a set of enhancements to the 802.11 MAC that allows parallel transmissions in situations when two neighboring nodes are either both receivers or transmitters, but a receiver and a transmitter are not neighbors. The performance of MACA-P in terms of system throughput is obtained through a simulation of the protocol using …

Are Use Case And Class Diagrams Complementary In Requirements Analysis? An Experimental Study On Use Case And Class Diagrams In Uml, Keng Siau, Lihyunn Lee

Research Collection School Of Computing and Information Systems

Despite the status of united modeling language (UML) as the de facto standard for object oriented modeling, it has received controversial reviews. The most controversial diagram in UML is the use case diagram. Some practitioners claim that use case diagrams are not valuable in requirements analysis and some have even argued that use case diagrams should not be part of UML. This research examined the values of use case diagram in interpreting requirements when use case diagrams are used in conjunction with class diagrams. In other words, the study investigated the possible synergetic values and relationships between the use case …

Clip-Based Similarity Measure For Hierarchical Video Retrieval, Yuxin Peng, Chong-Wah Ngo

Research Collection School Of Computing and Information Systems

This paper proposes a new approach and algorithm for the similarity measure of video clips. The similarity is mainly based on two bipartite graph matching algorithms: maximum matching (MM) and optimal matching (OM). MM is able to rapidly filter irrelevant video clips, while OM is capable of ranking the similarity of clips according to the visual and granularity factors. Based on MM and OM, a hierarchical video retrieval framework is constructed for the approximate matching of video clips. To allow the matching between a query and a long video, an online clip segmentation algorithm is also proposed to rapidly locate …

Trust Establishment In Large Scale Grid Settings, Bo Zhu, Tieyan Li, Huafei Zhu, Mohan S . Kankanhalli, Feng Bao, Robert H. Deng

Research Collection School Of Computing and Information Systems

Trust establishment is hard in grid architecture by the ad hoc nature. To set up trust in large scale of network is more difficult. In this paper, we propose an automatic key management (AKM) model and corresponding key construction schemes. The hierarchical structure is formed automatically and scale seamlessly in arbitrary network sized. Regions are configured differently according to various levels of risks faced. The novel model provides an integrated solution for self-organized trust establishment, upon which rich appliances are securely supported. It is automatic, flexible, and scalable. Furthermore, simulation results show that computation costs due to the variations are …

Fresh Water Supply Enhancement Through Rooftop Rainwater Harvesting For West Bank Rural Communities, Hani Iwhish

Water Resources Professional Project Reports

The West Bank region has long faced water shortages, and recent drought has amplified the problem. Disruptions due to political conflicts have reduced the frequency, reliability, and quality of water delivered by truck. These disruptions also increase the cost of water and limit income. Almost a third of people have no access to the existing water network, because they live beyond the reach of existing pipelines and cannot legally drill new wells. About a sixth of all households have some form of rooftop harvesting system, connected to a cistern, but these systems are often cracked, dirty, and contaminated. This paper …

A Novel Log-Based Relevance Feedback Technique In Content-Based Image Retrieval, Steven C. H. Hoi, Michael R. Lyu

Research Collection School Of Computing and Information Systems

Relevance feedback has been proposed as an important technique to boost the retrieval performance in content-based image retrieval (CBIR). However, since there exists a semantic gap between low-level features and high-level semantic concepts in CBIR, typical relevance feedback techniques need to perform a lot of rounds of feedback for achieving satisfactory results. These procedures are time-consuming and may make the users bored in the retrieval tasks. For a long-term study purpose in CBIR, we notice that the users' feedback logs can be available and employed for helping the retrieval tasks in CBIR systems. In this paper, we propose a novel …

Serologic Survey For Canine Infectious Diseases Among Sympatric Swift Foxes (Vulpes Velox) And Coyotes (Canis Latrans) In Southeastern Colorado, Eric M. Gese, Seija M. Karki, Mead L. Klavetter, Edward R. Schauster, Ann M. Kitchen

United States Department of Agriculture Wildlife Services: Staff Publications

Swift foxes (\'IL~VPGCY~ OX)a nd CoVi I otes (C~rrisl r~tr(~r~a.rse) sympatric canids distributed througllout rnany regions of tlie Great Plains of North America. ~h~ prevalence of canid diseases arnong these two species where they occur syiripatrically is presently unknown. Frorn January 1997 to January 2001, we collected blood salnples from 89 switt toxes and 122 coyotes oil the US Arlny Pifion Canyon Maneuver Site, 1,as Anilrlas County, SE lorado (USA). Seroprcvalence of ailtibodies against canine parvovirr~s (C13\i) was 71 % for adult (>9 nlo old) ailcl 38% for jrlveilile (59 Ino old) swift fbxes. Adult (21 yr old) and …

Annual Report To The Pastoral Lands Board Of Western Australia: 2003 / 2004 Financial Year, Rod Williams, Philip Thomas

Natural resources published reports

The Department of Agriculture has prepared this Annual Report for the Pastoral Lands Board of Western Australia for the financial year 2003 – 2004. This is the second report incorporating this framework and provides expanded information on issues and trends for a number of indicators of importance to Western Australia’s rangelands.

The Department of Agriculture’s services to the Board are outlined and environmental indicators based on scientific analysis of range condition trend are presented at the regional and property scales. Seasonal conditions at the state level with more specific information at the regional level and information relating to the assistance …

Chaos-Induced Escape Over A Potential Barrier, L. Y. Chew, Hian Ann, Christopher Ting, C. H. Lai

Research Collection Lee Kong Chian School Of Business

We investigate the statistical parity of a class of chaos-generated noises on the escape of strongly damped particles out of a potential well. We show that statistical asymmetry in the chaotic fluctuations can lead to a skewed Maxwell–Boltzmann distribution in the well. Depending on the direction of skew, the Kramers escape rate is enhanced or suppressed accordingly. Based on the Perron–Frobenious equation, we determine an analytical expression for the escape rate’s prefactor that accounts for this effect. Furthermore, our perturbative analysis proves that in the zeroth-order limit, the rate of particle escape converges to the Kramers rate.

Thermoelectricity In Natural And Synthetic Hydrogels, Brandon R. Brown

Physics and Astronomy

We describe a technique for measuring a Seebeck effect in gels and present data for three systems. notably distinct signals are obtained for gel originating in the electrosensitive organs of marine sharks, syntehtic collagen-based gel, and as a control, seawater, the gels' seawater simply confirms that gels suppress mass transport. The difference between synthetic gel and the gel of sharks shows that the charged polymers of the shark gel restrict mass transport much more successfully than the polumers of the collagen gel, and we submit that this sort of ion localization is key to the emergence of thermoelectricity in a …

Heights And Diophantine Problems, Lenny Fukshansky

CMC Faculty Publications and Research

Lecture given at Rice University, September 2004.

Interm Report Of A Pilot Study To Evaluate Impacts To Water Quality And Seagrass Meadows From The Green Mussel (Perna Viridis) Invasion In Hillsborough Bay, Tampa Bay, Florida., J.O.R. Johansson, W. M. Avery

Reports

The green mussel (Perna viridis) was discovered in Tampa Bay in 1999 and was first noted as a biofouler at a power generating plant. This was apparently the first record of this species in the U.S. Since 1999, green mussels have been found throughout Tampa Bay and in other marine locations outside Tampa Bay on the west-coast of Florida (Benson et al. 2001; Benson et al. 2002).

This report constitutes an interim report provided to the Tampa Bay Estuary Program (TBEP) to describe progress on the project to date. A final project report, including a detailed discussion of …

Cooperative Conservation - Interagency Volunteer Program Quarterly Progress Report: Period Ending September 30, 2004, Margaret N. Rees

Get Outdoors Nevada

Collaboration with Interagency Team

Although the task agreement formally commenced June 30, 2004, the agreement was not fully executed by both parties until July 29, 2004. In the first three months of this agreement, UNLV representatives have met with or communicated via email with the Interagency Volunteer Team on numerous occasions. At the first meeting on July 13, 2004, Government Technical Representative Bobbie Antonich and UNLV Public Lands Initiative Director Nancy Flagg met with the interagency team to discuss the overall goals for the Interagency Volunteer Program (IVP). The team was brought up-to-date on the status of the task agreement, …

Evaluation Of Fluorapatite As A Waste-Form Material: Fourth Quarter Report, June 1 - September 30, 2004, Dennis W. Lindle, Oliver Hemmers

Separations Campaign (TRP)

Fluorapatite, fluorinated calcium phosphate, has been identified as a potential matrix for the entombment of the zirconium fluoride fission product waste stream from the proposed FLEX process. If the efficacy of fluorapatite-based waste-storage can be demonstrated, then new and potentially more-efficient options for handling and separating high-level wastes, based on fluoride-salt extraction, will become feasible. This proposal will develop a dual-path research project to develop a process to fabricate a synthetic fluorapatite waste form for the ZrF₄, FP waste stream, characterize the waste form, examine its performance under environmental conditions, and correlate the behavior of the waste form …

Development Of A Systems Engineering Model Of The Chemical Separations Process: Final Report, Yitung Chen, Sean Hsieh

Separations Campaign (TRP)

The whole chemical separation process is complex to the point that definitely requires certain level of systematic coordination. To perform smoothly and meet the target extraction rates among those processes, this research proposed a general-purpose systems engineering model.

A general purposed systems engineering model, Transmutation Research Program System Engineering Model Project (TRPSEMPro), was developed based on the above design concept. The system model includes four main parts: System Manager, Model Integration, Study Plan, and Solution Viewer. TRPSEMPro can apply not only to chemical separation process, but also a general system model.

Software engineering and Object Oriented Analysis and Design (OOA&D) …

Developing A Sensing System For The Measurement Of Oxygen Concentration In Liquid Pb-Bi Eutectic: Quarterly Progress Report (July 1 – Sept. 30, 2004), Yingtao Jiang, Bingmei Fu

Transmutation Sciences Materials (TRP)

Dr. Jiang Ma and Mr. Xiaolong Wu worked in LANL between July 1 and Sept. 15 to conduct the experiment. Test of the corrosion of different materials in LBE was performed. The influence of the process of gas introduction to the LBE was studied. Data analysis work was performed based on accumulated data. In the same time, progress has been made in the simulation for transport in oxygen mixing, and one paper was presented in a conference. Another paper was composed and submitted to IEEE International Symposium of Circuits and Systems for the track Chemical Sensors. Preparation of a paper …

Network-Layer Selective Security, Casey T. Deccio

Theses and Dissertations

The Internet and other large computer networks have become an integral part of numerous daily processes. Security at the network layer is necessary to maintain infrastructure survivability in the case of cyber attacks aimed at routing protocols. In order to minimize undesired overhead associated with added security at this level, the notion of selective security is proposed. This thesis identifies elements in network topologies that are most important to the survivability of the network. The results show that the strategic placement of network security at critical elements will improve overall network survivability without the necessity of universal deployment.

Development Of A Systems Engineering Model Of The Chemical Separations Process, Yitung Chen, Sean Hsieh

Separations Campaign (TRP)

The whole chemical separation process is complex to the point that definitely requires certain level of systematic coordination. To perform smoothly and meet the target extraction rates among those processes, this research proposed a general-purpose systems engineering model.

A general purposed systems engineering model, Transmutation Research Program System Engineering Model Project (TRPSEMPro), was developed based on the above design concept. The system model includes four main parts: System Manager, Model Integration, Study Plan, and Solution Viewer. System Manager supervises all the case (problem) creation, and functionality definition. Model Integration identifies chemical extraction processes and their execution sequence. Study Plan is …

Estimating The Retransformed Mean In A Heteroscedastic Two-Part Model, Alan H. Welsh, Xiao-Hua Zhou

UW Biostatistics Working Paper Series

Two distribution free estimators are proposed to estimate the mean of a dependent variable after fitting a semiparametric two-part heteroscedastic regression model to a transformation of the dependent variable. We show that the proposed estimators are consistent and have asymptotic normal distributions. We also compare their finite-sample performance in a simulation study. Finally, we illustrate the proposed methods in a real-world example of predicting in-patient health care costs.