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2009

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Articles 6151 - 6180 of 6353

Full-Text Articles in Physical Sciences and Mathematics

General Formulation Of The Scattered Matter Waves By A Quantum Shutter, Yusuf Zi̇ya Umul Jan 2009

General Formulation Of The Scattered Matter Waves By A Quantum Shutter, Yusuf Zi̇ya Umul

Turkish Journal of Physics

The scattering process of matter waves by a quantum shutter is investigated by using the spectrum integral representation. The scattered fields are expressed in terms of the Fresnel function. It is shown that the obtained equation gives the Moshinsky function for a one dimensional problem of the plane wave. Also a general integral representation is derived for two dimensional problems. The scattering of matter waves for some special wave-packets are examined analytically and numerically.

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Prediction Of The Pressure-Induced Phase Transition In Gaas By The Positron Affinity, Belabbes Soudini Jan 2009

Prediction Of The Pressure-Induced Phase Transition In Gaas By The Positron Affinity, Belabbes Soudini

Turkish Journal of Physics

The thermalized positron charge distribution is calculated as a function of pressure variation in GaAs. Calculations have been carried out via the independent particle method (IPM) coupled with the empirical pseudopotential method (EPM). Initial results show a clear asymmetrical positron charge distribution relative to the bond center. From this positron affinity we have calculated the ionicity character with respect to the pressure variation using our empirical formula. Our results show an agreement with the thermochemical phase diagram proposed by Phillips.

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Effective Width And Expansion Energy Of The Interacting Condensed ^{87}Rb Bose Gas With Finite Size Effects, Ahmed Sayed Hassan, A. M. El-Badry Jan 2009

Effective Width And Expansion Energy Of The Interacting Condensed ^{87}Rb Bose Gas With Finite Size Effects, Ahmed Sayed Hassan, A. M. El-Badry

Turkish Journal of Physics

This work is devoted to study the temperature dependence of the effective width and expansion energy on the finite size and interaction effects (repulsive interactions). It is found that the effective size , and expansion energy in the radial direction E_y of a Bose gas follow a characteristic temperature dependence, i.e. , E_y \propto (T/T_0)^4 if T_0 < T and , E_y \propto (T/T_0) if T_0 > T. Our results show that these two parameters increases with the number of atoms, and with increasing repulsive interaction strength at temperature less than the transition temperature, (T < T_o); yet it has little effect at temperatures higher than the transition temperature (T > T_o). The obtained results are compared with the available experimental data for ^{87}Rb directly, full …

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Energy Levels Of The 6p_{3/2}Ns, Nd, Ng Autoionizing Series Of Pb I, Chao Zhou, Liang Liang, Ling Zhang Jan 2009

Energy Levels Of The 6p_{3/2}Ns, Nd, Ng Autoionizing Series Of Pb I, Chao Zhou, Liang Liang, Ling Zhang

Turkish Journal of Physics

Based on the weakest bound electron potential model (WBEPM) theory, six energy levels of the autoionizing Rydberg series 6pns 3/2[3/2]_1 (n = 15-25), 6pns 3/2[3/2]_2 (n = 15-25), 6pnd 3/2[3/2]_1 (n = 13-25), 6pnd 3/2[5/2]_3 (n = 13-25), 6pnd 3/2[7/2]_3 (n = 14-25) and 6png 3/2[5/2]_2 (n = 5-25) of Pb I are calculated. Foreign level perturbation corrections are taken into account in calculations of four series among them. The theoretical calculated results are in good agreement with the known experimental data, and some energies without experimental values are predicted.

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Superconducting State Parameters Of Al-Li Binary Alloys, Aditya M. Vora Jan 2009

Superconducting State Parameters Of Al-Li Binary Alloys, Aditya M. Vora

Turkish Journal of Physics

Theoretical computation of superconducting state parameters (SSP) viz. electron-phonon coupling strength \lambda , Coulomb pseudopotential \mu^* , transition temperature T_C , isotope effect exponent \alpha and effective interaction strength N_o V of face centered cubic Al_{1-C} Li_C binary alloys have been made extensively in the present work using a model potential formalism for the first time. A considerable influence of various exchange and correlation functions on \lambda and \mu^* is found from the present study. The present results of the SSP are found in qualitative agreement with the available experimental data wherever exist.

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Combined Analysis Of Solar Neutrino Data Within The Rsfp Framework Together With New Kamland Data, Deni̇z Yilmaz Jan 2009

Combined Analysis Of Solar Neutrino Data Within The Rsfp Framework Together With New Kamland Data, Deni̇z Yilmaz

Turkish Journal of Physics

A combined analysis of solar neutrino data together with the new KamLAND data is presented in the RSFP framework. It is investigated how the allowed regions are effected from the new KamLAND data at different \mu B values. Limits on \mu B value is found at the different confidence level intervals.

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Asphericity In The Fermi Surface Of D And F-Shell Metals, J. K. Baria, A. R. Jani Jan 2009

Asphericity In The Fermi Surface Of D And F-Shell Metals, J. K. Baria, A. R. Jani

Turkish Journal of Physics

Recently proposed pseudopotential has been used to calculate asphericity in the Fermi surface of d and f-shell metals along the three symmetry directions [100], [110] and [111]. The parameter of the potential has been determined by zero pressure condition and the exchange and correlation function due to Taylor has been incorporated. The present results are in good agreement with experimental findings for Cu, Ag, Au and Pd; while for other d and f- shell metals we could not found sufficient theoretical as well as experimental data for the asphericity in the Fermi Surface in order to workout a quantitative comparison. …

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Production Of Ybco Superconductor Sample By Powder-In-Tube Method (Pitm); And Effect Of Cd And Ga Doping On The System, Serkan Alagöz Jan 2009

Production Of Ybco Superconductor Sample By Powder-In-Tube Method (Pitm); And Effect Of Cd And Ga Doping On The System, Serkan Alagöz

Turkish Journal of Physics

In this study, YBa_2Cu_3O_{7-\delta} and Y_{0.5}X_{0.5}Ba_2Cu_3O_{7-\delta} (x = Ga, Cd) compounds are produced by Powder-In-Tube Method and electrical and physical characteristics of those samples were investigated. Following 3, 5 and 9 tons pressure applied to three sample groups (YBa_2Cu_3O_{7-\delta}, Y_{0.5}Cd_{0.5}Ba_2Cu_3O_{7-\delta}, Y_{0.5}Ga_{0.5}Ba_2Cu_3O_{7-\delta}), samples were examined via X-Ray diffraction, resistivity and SEM measurement. Considerable changes in Crystallographic properties of the YBCO samples, produced by using Powder-In-Tube Method for different pressure values, were observed. Under different magnetic fields conditions, resistance of the YBCO samples was measured and it was seen that samples had very pure and homogenous structure. Ga doping into YBCO composition …

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Electrical Characterization And Relaxation Behavior Of Lithium-Indium-Phosphate Glasses Via Impedance Spectroscopy, M. V. N. V. D. Sharma, A. V. Sarma, R. Balaji Rao Jan 2009

Electrical Characterization And Relaxation Behavior Of Lithium-Indium-Phosphate Glasses Via Impedance Spectroscopy, M. V. N. V. D. Sharma, A. V. Sarma, R. Balaji Rao

Turkish Journal of Physics

Phosphate glasses with various compositions of lithium oxide and indium oxide were synthesized by melt quenching technique. The glass forming ability parameter K_{gl} was characterized by differential thermal analysis. The electrical measurements for all the glass samples were carried out in the frequency range of 10 Hz to 10^{6} Hz and at a temperature range of 393-513 K by the Impedance spectroscopy. Frequency dependent conductivity follows the power law. The ac conductivity increases with temperature following the Arrhenius law. Master curve in the scaling analysis suggesting the temperature independent conduction relaxation mechanism.

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Generation Of Ultrafast Bright And Dark Pulse On Silicon Chip With Integrated Mach-Zehnder Interferometer Configuration, Jianwei Wu, Fengguang Luo Jan 2009

Generation Of Ultrafast Bright And Dark Pulse On Silicon Chip With Integrated Mach-Zehnder Interferometer Configuration, Jianwei Wu, Fengguang Luo

Turkish Journal of Physics

In this paper we propose and simulate ultrafast femtosecond bright and dark pulses, obtained simultaneously at the same center wavelength, based on silicon-on-insulator (SOI) waveguides in Mach-Zehnder interferometer (MZI) configuration; the ultrafast pulsed pump is injected into one MZI's arm and a continuous wave component (CW) is divided equally into the two MZI arms. Numerical results show that properties of the generated bright and dark pulses are strongly dependent on the launching optical powers of both the pump pulse and CW carriers, and on the waveguide length.

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Unsteady Free Convection Flow With Thermal Radiation Past A Vertical Porous Plate With Newtonian Heating, Promise Mebine, Emmanuel Munakurogha Adigio Jan 2009

Unsteady Free Convection Flow With Thermal Radiation Past A Vertical Porous Plate With Newtonian Heating, Promise Mebine, Emmanuel Munakurogha Adigio

Turkish Journal of Physics

This paper considers exact solutions of unsteady free convection flow with thermal radiation past a vertical porous plate with Newtonian heating. The technique of Laplace transform was employed in deriving the solutions to the governing flow and energy equations. A parametric study of all parameters involved was conducted, and a representative set of results showing the effect of the radiation parameter N, the ratio of uniform suction to characteristic velocity parameter R, and the free convection parameter Gr on the velocity and temperature are illustrated graphically. The skin friction or shear and heat flux are discussed quantitatively. It is evident …

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Composition Dependent Of Dielectric Properties In Se_{100-X}Pb_X Glassy Alloys, Jyoti Sharma, Santosh Kumar Jan 2009

Composition Dependent Of Dielectric Properties In Se_{100-X}Pb_X Glassy Alloys, Jyoti Sharma, Santosh Kumar

Turkish Journal of Physics

In this paper we report the composition dependent of dielectric properties in Se_{100-x}Pb_x (x = 0, 2, 4, 6 and 10) glassy alloys. The temperature and frequency dependence of the dielectric constants and the dielectric losses in the above glassy systems in the frequency range 1 kHz-5 MHz and temperature range 300-340 K have been measured. It has been found that dielectric constant and the dielectric loss both are highly dependent on frequency and temperature and also found to be increased with increasing concentration of Pb in pure amorphous Se. The results have been interpreted in terms of increase in …

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The Electrical Conduction Mechanisms And Thermoelectric Power Of Snse Single Crystals, M. M. Nassary Jan 2009

The Electrical Conduction Mechanisms And Thermoelectric Power Of Snse Single Crystals, M. M. Nassary

Turkish Journal of Physics

Single crystals of SnSe were prepared in our laboratory by a special modified Bridgman technique. Measurements of the electrical conductivity and Hall effect between 141 K and 553 K were carried out on SnSe sample in two crystallographic directions. The investigated sample was found to be of p-type conductivity. The Hall mobilities parallel and perpendicular to layers plane at room temperature, were 7835.9 cm^2/ V \cdots and 7274.7 cm^2/ V.s, respectively. The free carrier concentration P = 3.52 \times 10^{12} cm^{-3} at room temperature. Also, the thermoelectric power (TEP) was investigated in the temperature range from 176 to 553 K. …

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Growth And Microindentation Analysis Of Pure And Doped Sb_2se_3 Crystals, K. A. Chandrasekharan, A. G. Kunjomana Jan 2009

Growth And Microindentation Analysis Of Pure And Doped Sb_2se_3 Crystals, K. A. Chandrasekharan, A. G. Kunjomana

Turkish Journal of Physics

Pure and doped antimony selenide (Sb_2Se_3, Sb_2Se_{2.8}Te_{0.2}, and Sb_2Se_{2.6}Te_{0.4}) crystals have been grown from melt by the Bridgman Stockbarger method. X-ray powder diffraction analysis was carried out to determine the lattice parameters of the grown samples. The morphology of cleavage planes was observed using SEM. Energy dispersive analysis by X-rays (EDAX) was done to find out the chemical composition of the grown samples. Correlation of microhardness with other mechanical characteristics such as toughness, brittleness, and yield strength, has been investigated. The effects of Te doping on the mechanical behaviour and energy gap were also studied on the cleavage faces.

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Thermoelectric Power And Low-Field Electron Mobility In Al_Xga_{1-X}N Lattice-Matched To Gan, H. Arabshahi Jan 2009

Thermoelectric Power And Low-Field Electron Mobility In Al_Xga_{1-X}N Lattice-Matched To Gan, H. Arabshahi

Turkish Journal of Physics

The results of thermoelectric power and electron drift mobility in Al_xGa_{1-x}N lattice-matched to GaN are calculated for different temperatures, free-electron concentrations and compositions. The two-mode nature of the polar optic phonons is considered jointly with deformation potential acoustic, piezoelectric, alloy and ionized-impurity scattering. Band non-parabolicity, admixture of p functions, arbitrary degeneracy of the electron distribution and the screening effects of free carriers on the scattering probabilities are incorporated. The Boltzmann equation is solved by an iterative technique using the currently established values of the material parameters. The iterative results are in fair agreement with other recent calculations obtained using the …

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Study Of Second-Class Currents Effects On Polarization Characteristics In Quasi-Elastic Neutrino (Anti-Neutrino) Scattering By Nuclei, Adamou Ousmane Manga, Almoustapha Aboubacar Jan 2009

Study Of Second-Class Currents Effects On Polarization Characteristics In Quasi-Elastic Neutrino (Anti-Neutrino) Scattering By Nuclei, Adamou Ousmane Manga, Almoustapha Aboubacar

Turkish Journal of Physics

The differential cross section of quasi-elastic neutrino scattering by nuclei is computed. The numerical analysis of energy dependence of the spin asymmetry, the angular electron-neutrino (e\nu) correlation and the charge asymmetry coefficients shows that the relative contribution of the second-class current (SCC) tensor form factor can reach some tens of percents in the case of particular values of final nuclei alignment and polarization.

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Behavior Of Transition Amplitude And Evolution Of The Energy Of Quantum Kicked Rotator, Abdolrasoul Gharaati Jan 2009

Behavior Of Transition Amplitude And Evolution Of The Energy Of Quantum Kicked Rotator, Abdolrasoul Gharaati

Turkish Journal of Physics

I give certain analytical properties of quantum kicked rotators, both theoretic and observed from computation. I give an expression for the wave function between two successive impulses. An element of the transition matrix, the matrix that takes the wave function from one impulse to another, exponentially falls away from the main diagonal. The decay parameter is given for a few special cases of a periodic potential. Finally, the transition matrix is used to derive the time evolution of the energy for periodic cases and for fundamental resonances. The empirical expressions of Dorizzi et al. are compatible with our analytical results.

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Strong Field Effects On Pulsar Arrival Times: General Orientations, Yan Wang, Teviet Creighton, Richard H. Price, Fredrick A. Jenet Jan 2009

Strong Field Effects On Pulsar Arrival Times: General Orientations, Yan Wang, Teviet Creighton, Richard H. Price, Fredrick A. Jenet

Physics & Astronomy Faculty Publications

A pulsar beam passing close to a black hole can provide a probe of very strong gravitational fields even if the pulsar itself is not in a strong field region. In the case that the spin of the hole can be ignored, we have previously shown that all strong field effects on the beam can be understood in terms of two \"universal\" functions: F(φin) and T(φin) of the angle of beam emission φin; these functions are universal in that they depend only on a single parameter, the pulsar/black hole distance from which the beam is emitted. Here we apply this …

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Highly Stereoselective B-Lactam Synthesis Via The Staudinger Reaction Using Poly Aromatic Imines, Debasish Bandyopadhyay, Monica Xavier, Bimal K. Banik Jan 2009

Highly Stereoselective B-Lactam Synthesis Via The Staudinger Reaction Using Poly Aromatic Imines, Debasish Bandyopadhyay, Monica Xavier, Bimal K. Banik

School of Integrative Biological & Chemical Sciences (Formerly Dept. of Chemistry)

Highly stereoselective synthesis of a few trans 3-phthalimido substituted B-lactams has been achieved following Staudinger reaction.

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Real-Time Regularized Ultrasound Elastography, Hassan Rivaz Jan 2009

Real-Time Regularized Ultrasound Elastography, Hassan Rivaz

Link Foundation Modeling, Simulation and Training Fellowship Reports

This paper introduces two real-time elastography techniques based on analytic minimization (AM) of regularized cost functions. The first method (1D AM) produces axial strain and integer lateral displacement, while the second method (2D AM) produces both axial and lateral strains. The cost functions incorporate similarity of RF data intensity and displacement continuity, making both AM methods robust to small decorrelations present throughout the image. We also exploit techniques from robust statistics to make the methods resistant to large local decorrelations. We further introduce Kalman filtering for calculating the strain field from the displacement field given by the AM methods. Simulation …

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Evaluating Earnings Management With Derivatives And The Use Of Accounting Accruals: A Quasi Experimental Approach, Margot S. Geagon Jan 2009

Evaluating Earnings Management With Derivatives And The Use Of Accounting Accruals: A Quasi Experimental Approach, Margot S. Geagon

Walden Dissertations and Doctoral Studies

Most companies listed on the S&P 500 index have reported smoothed earnings since the 1990s inspiring questions from regulators about the accuracy of financial statements. In 1998, the Financial Accounting Standards Board issued SFAS No. 133 (Accounting for Derivative Instruments and Hedging Activities) to establish accounting and reporting standards for derivative instruments. In 2002, the Sarbanes-Oxley Act (SOX) was issued to eradicate earnings management activities and improve transparency in financial reporting. Although many studies have been conducted to evaluate changes in reporting requirements, much less is known about the effectiveness of these regulations on earning smoothing with discretionary accruals (DA) …

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A Fuzzy Hierarchical Decision Model And Its Application In Networking Datacenters And In Infrastructure Acquisitions And Design, Michael Khader Jan 2009

A Fuzzy Hierarchical Decision Model And Its Application In Networking Datacenters And In Infrastructure Acquisitions And Design, Michael Khader

Walden Dissertations and Doctoral Studies

According to several studies, an inordinate number of major business decisions to acquire, design, plan, and implement networking infrastructures fail. A networking infrastructure is a collaborative group of telecommunications systems providing services needed for a firm's operations and business growth. The analytical hierarchy process (AHP) is a well established decision-making process used to analyze decisions related to networking infrastructures. AHP is concerned with decomposing complex decisions into a set of factors and solutions. However, AHP has difficulties in handling uncertainty in decision information. This study addressed the research question of solutions to AHP deficiencies. The solutions were accomplished through the …

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An Analysis Of The Impact Of Information Systems On The Level Of Trust In The Construction Industry, Michael Wayne Jones Jan 2009

An Analysis Of The Impact Of Information Systems On The Level Of Trust In The Construction Industry, Michael Wayne Jones

Walden Dissertations and Doctoral Studies

Even though the current level of communication and information sharing is greater than it has ever been throughout the history of the construction industry, the problem under investigation stems from the results of current research that indicate that many major projects have difficulty in achieving client expectations, resulting in a negative image of the construction industry. The purpose of this study was to analyze the impact on the level of trust in the use of information systems between construction firms and their clients. The theoretical foundations of this research were based in interdependence and coordination theories. While information systems enable …

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Ontology-Based Business Process Customization For Composite Web Services, Qianhui (Althea) Liang, Xindong Wu, E. K. Park, T. Khoshgoftaar, C. Chi Jan 2009

Ontology-Based Business Process Customization For Composite Web Services, Qianhui (Althea) Liang, Xindong Wu, E. K. Park, T. Khoshgoftaar, C. Chi

Research Collection School Of Computing and Information Systems

A key goal of the Semantic Web is to shift social interaction patterns from a producer-centric paradigm to a consumer-centric one. Treating customers as the most valuable assets and making the business models work better for them are at the core of building successful consumer-centric business models. It follows that customizing business processes constitutes a major concern in the realm of a knowledge-pull-based human semantic Web. This paper conceptualizes the customization of service-based business processes leveraging the existing knowledge of Web services and business processes. We represent this conceptualization as a new Extensible Markup Language (XML) markup language Web Ontology …

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Web Social Mining, Hady W. Lauw, Ee Peng Lim Jan 2009

Web Social Mining, Hady W. Lauw, Ee Peng Lim

Research Collection School Of Computing and Information Systems

No abstract provided.

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Computing Medoids In Large Spatial Datasets, Kyriakos Mouratidis, Dimitris Papadias, Spiros Papadimitriou Jan 2009

Computing Medoids In Large Spatial Datasets, Kyriakos Mouratidis, Dimitris Papadias, Spiros Papadimitriou

Research Collection School Of Computing and Information Systems

In this chapter, we consider a class of queries that arise in spatial decision making and resource allocation applications. Assume that a company wants to open a number of warehouses in a city. Let P be the set of residential blocks in the city. P represents customer locations to be potentially served by the company. At the same time, P also comprises the candidate warehouse locations because the warehouses themselves must be opened in some residential blocks.

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Distributed Utility-Based Rate Adaptation Protocols For Prioritized, Quasi-Elastic Flows, Sharanya Eswaran, Matthew P. Johnson, Archan Misra, Thomas La Porta Jan 2009

Distributed Utility-Based Rate Adaptation Protocols For Prioritized, Quasi-Elastic Flows, Sharanya Eswaran, Matthew P. Johnson, Archan Misra, Thomas La Porta

Research Collection School Of Computing and Information Systems

This paper considers rate adaptation for streaming multimedia data in a wireless sensor network (WSN) consisting of multiple missions, where each mission subscribes to data streams from multiple sensors, and each sensor's data is utilized by multiple heterogenous missions. We specifically consider the application of the distributed network utility maximization (NUM) framework to a previously unconsidered scenario where the different missions have different priorities, as well as minimum utility demands. When all the utility demands are feasible, we first show that the addition of a penalty for failing to reach the minimum utility demand to the base NUM protocol leads …

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Control-Theoretic, Mission-Driven, Optimization Techniques For Wireless Sensor Networks, Archan Misra, Sharanya Eswaran, Thomas La Porta Jan 2009

Control-Theoretic, Mission-Driven, Optimization Techniques For Wireless Sensor Networks, Archan Misra, Sharanya Eswaran, Thomas La Porta

Research Collection School Of Computing and Information Systems

Network Utility Maximization (NUM) techniques, which cast resource sharing problems as one of distributed utility maximization, have been investigated for a variety of optimization problems in wireless and wired networks. Our recent work has extended the NUM framework to consider the case of resource sharing by multiple competing missions in a military-centric wireless sensor network (WSN) environment. Our enhanced NUM-based protocols provide rapid and dynamic mission-based adaptation of tactical wireless networks to support the transport of sensor data streams with very small control overhead. In particular, we focus specifically on mechanisms that capture the joint nature of mission utilities and …

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Localized Monitoring Of Knn Queries In Wireless Sensor Networks, Yuxia Yao, Xueyan Tang, Ee Peng Lim Jan 2009

Localized Monitoring Of Knn Queries In Wireless Sensor Networks, Yuxia Yao, Xueyan Tang, Ee Peng Lim

Research Collection School Of Computing and Information Systems

Wireless sensor networks have been widely used in civilian and military applications. Primarily designed for monitoring purposes, many sensor applications require continuous collection and processing of sensed data. Due to the limited power supply for sensor nodes, energy efficiency is a major performance concern in query processing. In this paper, we focus on continuous kNN query processing in object tracking sensor networks. We propose a localized scheme to monitor nearest neighbors to a query point. The key idea is to establish a monitoring area for each query so that only the updates relevant to the query are collected. The monitoring …

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Partially Materialized Digest Scheme: An Efficient Verification Method For Outsourced Databases, Kyriakos Mouratidis, Dimitris Sacharidis, Hwee Hwa Pang Jan 2009

Partially Materialized Digest Scheme: An Efficient Verification Method For Outsourced Databases, Kyriakos Mouratidis, Dimitris Sacharidis, Hwee Hwa Pang

Research Collection School Of Computing and Information Systems

In the outsourced database model, a data owner publishes her database through a third-party server; i.e., the server hosts the data and answers user queries on behalf of the owner. Since the server may not be trusted, or may be compromised, users need a means to verify that answers received are both authentic and complete, i.e., that the returned data have not been tampered with, and that no qualifying results have been omitted. We propose a result verification approach for one-dimensional queries, called Partially Materialized Digest scheme (PMD), that applies to both static and dynamic databases. PMD uses separate indexes …

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