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2011

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Articles 7381 - 7410 of 7765

Full-Text Articles in Physical Sciences and Mathematics

Uis Mapping Grades, Ph. Häuselmann Jan 2011

Uis Mapping Grades, Ph. Häuselmann

International Journal of Speleology

No abstract provided.

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Effective Size And Expansion Energy Of A Bose-Einstein Condensate In A 3d Non-Cubic Optical Lattice, Shemi S. M. Soliman Jan 2011

Effective Size And Expansion Energy Of A Bose-Einstein Condensate In A 3d Non-Cubic Optical Lattice, Shemi S. M. Soliman

Turkish Journal of Physics

This work is devoted to study the temperature dependence of the effective size and expansion energy E_{x,z} of a Bose-Einstein condensate in a 3D non-cubic optical lattice. Correction due to the finite size, interatomic interaction and the deepness of the lattice potential are given simultaneously. The calculated results show that these two parameters increase with the lattice depth or the relative frequency 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). Both the effective size and expansion energy follow a characteristic temperature dependence, i.e. , E \propto(T/T_0)^4 if T < T_0 and , E \propto (T/T_0) if T > T_0. For a 3D non cubic optical potential the effect of …

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Analytical Expression For Mode-Coherence Coefficient Of A Uniformly-Distributed Wave Propagating In Different Homogeneous Media, Noor Ezzulddin Naji Jan 2011

Analytical Expression For Mode-Coherence Coefficient Of A Uniformly-Distributed Wave Propagating In Different Homogeneous Media, Noor Ezzulddin Naji

Turkish Journal of Physics

Presented is a derivation of an analytical expression for the mode-coherence coefficients of uniform-distributed wave propagating within different homogeneous media-as in the case of hyperbolic Gaussian beams-and a simple method involving the superposition of two such beams is proposed. The results obtained from this work are very applicable to study and analysis of Hermite-Gaussian beam propagation, especially in the problems of radiation-matter interaction, and laser beam propagation such as employed in free-space and fiber optical communications.

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Dynamical Behavior Of Traveling Wave Solutions For The K(2,2) Equation, Lina Zhang Jan 2011

Dynamical Behavior Of Traveling Wave Solutions For The K(2,2) Equation, Lina Zhang

Turkish Journal of Physics

In this paper, we discuss the qualitative behavior of degenerate singular points for the K(2,2) equation. By analyzing the different dynamical behaviors of the singular system and its associated regular system, we come to the conclusion that for the singular system the smoothness property of its orbits, which have intersection point(s) with the singular straight line, will not be destroyed. Meanwhile, the corresponding smooth traveling wave solutions for the K(2,2) equation are obtained.

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Resonant Transfer Excitation Followed By X-Ray For Boron-Like Ions, Hassan Ramadan Jan 2011

Resonant Transfer Excitation Followed By X-Ray For Boron-Like Ions, Hassan Ramadan

Turkish Journal of Physics

Theoretical cross sections for resonant transfer excitation followed by x-ray emission (RTEX) are calculated for the collisions of some ions in the series of the Boron-like ions with H_2 as a target. The calculations have been done for C II, N III, O IV, F V, Ar XIV and Fe XXII ions by folding their dielectronic recombination (DR) cross sections over the momentum distribution (Compton profile) of H_2 target gas. Calculations have been performed from both ground and metastable initial states, in LS - coupling, allowing for \triangle n = 0 excitations. In the present work, the RTEX cross sections …

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Electrons Trajectories In Electromagnetically Pumped Free Electron Laser With A Constant Reverse Guide Magnetic Field, Ahmad Omar Jan 2011

Electrons Trajectories In Electromagnetically Pumped Free Electron Laser With A Constant Reverse Guide Magnetic Field, Ahmad Omar

Turkish Journal of Physics

An exact solution to the quartic equation in the wiggler frequency \omega_w, which represents the dispersion relation for this system, is obtained. The effects of the frequency of the wiggler \omega_w on the electron's velocities (v_{\vert \vert} and v_w) are investigated. The regions of interest for the allowed wiggler frequency \omega_w for both group I and group II electron trajectories are discussed.

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Strong Optical Injection Locked Semiconductor Laser For High Bit Rate Chaotic Optical Communications, Muzahim Ibrahim Azawe, Ragaad Habib Saied Jan 2011

Strong Optical Injection Locked Semiconductor Laser For High Bit Rate Chaotic Optical Communications, Muzahim Ibrahim Azawe, Ragaad Habib Saied

Turkish Journal of Physics

We present in this article how strong optical injection can produce chaotic dynamics in the output of the semiconductor laser that is preferable for perfect encrypted optical communication networks. Significant increase in the relaxation resonance frequency was found implying higher degree of enhancement in modulation bandwidth. Numerical investigations under the condition of strong optical injection locking of the slave laser shows that instabilities in the photon number was observed and had settled down after a time of in the order of carrier lifetime. The model presented can be used to extract the characteristic parameters of the injection locking for detuning …

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2n-Dimensional At Fujii Model Instanton-Like Solutions And Coupling Constant's Role Between Instantons With Higher Derivatives, Mehmet Keçeci̇ Jan 2011

2n-Dimensional At Fujii Model Instanton-Like Solutions And Coupling Constant's Role Between Instantons With Higher Derivatives, Mehmet Keçeci̇

Turkish Journal of Physics

An instanton-like solution is considered for a class of two-dimensional conformal model with Liouville term. The model expressed here is a new higher-dimensional model with scalar-spinor interaction on even-dimensional spaces, and is a generalization of the even-dimensional Fujii model. A recurrence relation for the Fujii model and coupling constant's indices between relations with interaction constant is extracted. The behavior of Gürsey, Akdeniz-Smailagi' c and Fujii coupling constants in 4-dimensional conformal models are examined.

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Metals And Metal Oxides Particles Produced By Pulsed Laser Ablation Under High Vacuum, Khurram Siraj, Yasir Sohail, Aasma Tabassum Jan 2011

Metals And Metal Oxides Particles Produced By Pulsed Laser Ablation Under High Vacuum, Khurram Siraj, Yasir Sohail, Aasma Tabassum

Turkish Journal of Physics

A pulsed KrF Excimer laser (248 nm, 15 mJ) was utilized to synthesize different particles on (111) Si substrate under vacuum \sim 10^{-6} torr using Aluminum (Al), Platinum (Pt), Tungsten (W), Molybdenum (Mo), Cadmium Oxide (CdO), and Yttrium Oxide (Y_2O_3) targets. Scanning electron microscope (SEM) was used to study particle size distribution on silicon substrate. The size of individual metal particles was found to be ranging from 71 nm to 2 \mu m whereas metal oxides particles were found in the range of 71 nm to 1.1 \mu m. The particles below 100 nm are formed by gas phase condensation …

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Influence Of Doping And Heat Treatments On Carriers Mobility In Polycrystalline Silicon Thin Films For Photovoltaic Application, Beddiaf Zaidi, Bouzid Hadjoudja, Houda Felfli, Allaoua Chibani Jan 2011

Influence Of Doping And Heat Treatments On Carriers Mobility In Polycrystalline Silicon Thin Films For Photovoltaic Application, Beddiaf Zaidi, Bouzid Hadjoudja, Houda Felfli, Allaoua Chibani

Turkish Journal of Physics

In this work, we investigate the influence of doping as well as heat treatments on the mobility of the carriers in polycrystalline silicon layers. It was found that any increase in both parameters leads to an increase in the mobility of the carriers. Such mobilities were shown to be higher in boron doped layers that those doped with arsenic. Moreover, for strong arsenic doping, after the initial increase, we observed a saturation region followed by a final decrease of carrier mobility.

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Characteristics Cd_{0.3}Sn_{0.7}Se Thin Films As Absorber Materials For Solar Cell Devices, Salma Mahdi Shaban, Raad Mohammad Saleh, Ahmed Saleh Ahmed Jan 2011

Characteristics Cd_{0.3}Sn_{0.7}Se Thin Films As Absorber Materials For Solar Cell Devices, Salma Mahdi Shaban, Raad Mohammad Saleh, Ahmed Saleh Ahmed

Turkish Journal of Physics

Cadmium Tin Selenide compound Cd_{0.3}Sn_{0.7}Se was prepared by direct reaction of high-purity elemental Cadmium, Tin and selenium. Cd_{0.3}Sn_{0.7}Se thin films were prepared on to well-cleaned glass substrates by vacuum thermal evaporation technique at room temperature of different thicknesses. The X-ray diffraction studies revealed that all the deposited films are amorphous in nature and exhibiting polycrystalline structure when are annealed at 348 K and 373 K. The crystallites were found to have a preferred orientation along the (111) direction. The analysis of its optical characteristics indicated the ability of these films to absorb the visible light due to its graded energy …

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Effect Of Cdcl_2/Annealing On The Crystalline Transformation Of Cdte Thin Films Grown By Evaporation At A Low Substrate Temperature, İsmai̇l Polat, Sali̇h Yilmaz, Emi̇n Bacaksiz, Mustafa Altunbaş, Murat Tomaki̇n Jan 2011

Effect Of Cdcl_2/Annealing On The Crystalline Transformation Of Cdte Thin Films Grown By Evaporation At A Low Substrate Temperature, İsmai̇l Polat, Sali̇h Yilmaz, Emi̇n Bacaksiz, Mustafa Altunbaş, Murat Tomaki̇n

Turkish Journal of Physics

The structural and optical properties of CdTe thin films prepared at a low substrate temperature were investigated before and after the CdCl_2/annealing. The crystal structure of CdTe film was cubic with a strong (111) preferential orientation. Annealing at 400 °C without CdCl_2 treatment results in a decrease in the (111) peak intensity while the intensities of the (220), (311) and (331) peaks appeared, indicating that the texture is significantly changed. However, after the CdCl_2/annealing, the film exhibited a hexagonal phase as a dominant structure. The scanning electron microscopy patterns showed that the as-deposited and annealed samples had almost the same …

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Hydromagnetic Thermal Boundary Layer Flow Of A Perfectly Conducting Fluid, Kalidas Das Jan 2011

Hydromagnetic Thermal Boundary Layer Flow Of A Perfectly Conducting Fluid, Kalidas Das

Turkish Journal of Physics

Using successive approximation technique, an analysis of unsteady hydromagnetic boundary layer flow with thermal relaxation of perfectly conducting, viscous incompressible fluid past a semi-infinite porous plate in presence of heat absorbing sinks is carried out. The expression for velocity and temperature fields, local skin friction coefficient, local heat transfer coefficient etc have been derived when the free stream velocity exponentially depends on time. The effects of different parameters entering into the problem are shown graphically and discussed numerically.

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Electronic Structure Of The Ge And Se Vacancies In Gese Layered Semiconductor, Zakir Jahangirli Jan 2011

Electronic Structure Of The Ge And Se Vacancies In Gese Layered Semiconductor, Zakir Jahangirli

Turkish Journal of Physics

We report the results of a theoretical investigation of electronic properties of ideal cation and anion vacancies in GeSe. The calculations have been performed using self-consistent Green's function method. The bulk electronic structure is described by a tight-binding Hamiltonian in the bases sets of Linear Combinations of Atomic Orbitals (LCAO). The Green's function of the perfect crystal evaluated using an eigenfunction expansion employing wave functions and band structures obtained from a self-consistent, pseudopotential, local-density-functional calculation. The defect potential is calculated using occupied electron states of the perturbed system. Results are obtained in terms of vacancy bound states, vacancy resonances, and …

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A High Luminosity Erl On Ring E^-E^+ Collider For A Super Charm Factory, Erdal Recepoglu, Saleh Sultansoy Jan 2011

A High Luminosity Erl On Ring E^-E^+ Collider For A Super Charm Factory, Erdal Recepoglu, Saleh Sultansoy

Turkish Journal of Physics

A high luminosity energy recovery linac-on-ring type electron-positron collider operating as super charm factory is proposed. It is shown that a luminosity above L = 10^{35}cm^{-2}s^{-1} can be achieved for center of mass energy \sqrt{s}=3.77 GeV. The physics goals of this machine in investigation for charmed particles properties are briefly discussed.

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Editorial, Jo De Waele Jan 2011

Editorial, Jo De Waele

International Journal of Speleology

No abstract provided.

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Microwave-Induced Indium-Catalyzed Synthesis Of Pyrrole Fused With Indoline In Water, Dina Abrego, Debasish Bandyopadhyay, Bimal K. Banik Jan 2011

Microwave-Induced Indium-Catalyzed Synthesis Of Pyrrole Fused With Indoline In Water, Dina Abrego, Debasish Bandyopadhyay, Bimal K. Banik

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

An expeditious microwave-induced indium metal-catalyzed synthesis of pyrrole fused with indoline in water is developed by reacting isatin and 4-hydroxyproline.

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Microwave-Induced Bismuth Nitrate-Catalyzed Expeditious Enamination Of Β-Dicarbonyl Compounds Under Solvent-Free Conditions, Debasish Bandyopadhyay, Bimal K. Banik Jan 2011

Microwave-Induced Bismuth Nitrate-Catalyzed Expeditious Enamination Of Β-Dicarbonyl Compounds Under Solvent-Free Conditions, Debasish Bandyopadhyay, Bimal K. Banik

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

Bismuth nitrate-catalyzed, automated microwave-assisted expeditious synthesis of β- enaminones and β-enaminoesters has been carried out in an efficient manner under solvent-free condition. The reaction is general for primary, secondary (cyclic, heterocyclic and acyclic), benzylic as well as aromatic amines.

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Microwave-Induced Stereoselectivity Of Β-Lactam Formation: Effects Of Solvents, Debasish Bandyopadhyay, Marco Yanez, Bimal K. Banik Jan 2011

Microwave-Induced Stereoselectivity Of Β-Lactam Formation: Effects Of Solvents, Debasish Bandyopadhyay, Marco Yanez, Bimal K. Banik

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

Synthesis of 3, 4-disubstituted 2-azetidinones has been achieved following Staudinger reaction under microwave-induced conditions. The stereoselectivity of β-lactam formation depends on the nature of the solvents used in the reaction.

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Antimicrobial Activity Of Eugenol Derivatives, George Eyambe, Luis Canales, Bimal K. Banik Jan 2011

Antimicrobial Activity Of Eugenol Derivatives, George Eyambe, Luis Canales, Bimal K. Banik

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

The antibacterial properties of the clove plant are due to the presence of eugenol, an aromatic phenolic compound. Eugenol was isolated from clove by stem distillation. The alkene group in eugenol was epoxidized resulting in the synthesis of epoxide-eugenol. The heterocyclic ring in epoxide was cleaved to a bromoalcohol derivative. The compounds synthesized epoxideeugenol, bromo alcohol and euginol were tested for antimicrobial activity against Staphylococcus aureus (ATCC 25923). Epoxide-eugenol was found to be the most effective antimicrobial agent among the three compounds tested.

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Review: The Mathematics Of Sex: How Biology And Society Conspire To Limit Talented Women And Girls, Susan Jane Colley Jan 2011

Review: The Mathematics Of Sex: How Biology And Society Conspire To Limit Talented Women And Girls, Susan Jane Colley

Faculty & Staff Scholarship

No abstract provided.

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Novel Optical Remote Sensing Technology For Prediction Of Harmful Algal Blooms, Elizabeth Tobin Jan 2011

Novel Optical Remote Sensing Technology For Prediction Of Harmful Algal Blooms, Elizabeth Tobin

Link Foundation Ocean Engineering and Instrumentation Fellowship Reports

Harmful Algal Blooms (HABs) are outbreaks of planktonic algae that threaten public health, degrade aquatic ecosystems and cause major economic losses. Most HABs are detected only after they reach an advanced stage, when they have already caused significant ecological and economic damage. However, many HAB-forming species have two distinct life stages, a dormant benthic stage and a vegetative pelagic stage.The primary objective of this project was to construct and test a prototype of an autonomous optical sensor for the detection and characterization of HAB-forming algae as they emerge from the sediments.

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Exploring Identity Management At Community Colleges In Texas With Open Access To College Computer Networks, Michael John Callahan Jan 2011

Exploring Identity Management At Community Colleges In Texas With Open Access To College Computer Networks, Michael John Callahan

Walden Dissertations and Doctoral Studies

The study addressed the lack of identity management practices in Texas community colleges to identify guest users who access college computers. Guest user access is required by Texas law and is part of the state's mission to bridge the technology gap; however, improper identification methods leave the college vulnerable to liability issues. The purpose of this study was to eliminate or mitigate liabilities facing colleges by creating and using security policies to identify guest users. This study combined the theoretical concepts of Cameron's internal security management model with the external trust models of the Liberty Alliance and Microsoft's Passport software. …

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Computational Studies Of New Materials Ii: From Ultrafast Processes And Nanostructures To Optoelectronics, Energy Storage And Nanomedicine, Thomas George, D. Jelski, R. Letfullin, G. Zhang Jan 2011

Computational Studies Of New Materials Ii: From Ultrafast Processes And Nanostructures To Optoelectronics, Energy Storage And Nanomedicine, Thomas George, D. Jelski, R. Letfullin, G. Zhang

Chemistry & Biochemistry Faculty Works

No abstract provided.

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Learning Without Onboarding: How Assessing And Evaluating Learning Benefits New Information Technology Hires, Dory L. Morris Jan 2011

Learning Without Onboarding: How Assessing And Evaluating Learning Benefits New Information Technology Hires, Dory L. Morris

Walden Dissertations and Doctoral Studies

Onboarding ensures learning success through sharing and acquiring knowledge to remain competitive. However, little is known about new Information Technology (IT) hires' learning needs in the absence of onboarding; therefore, the purpose of this case study was to examine, increase, and retain their technical knowledge at the Unified Communications Company (UCC). Following the theoretical model of knowledge management, which holds that knowledge is the key to confirm learning and knowledge sharing, the research questions were used to examine how the company assessed and increased their technical knowledge and how they taught their culture in the absence of onboarding. A qualitative …

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Continual Energy Management Dynamics: Energy Efficiency In U.S. Automotive Manufacturing Industry, Cem O. Onus Jan 2011

Continual Energy Management Dynamics: Energy Efficiency In U.S. Automotive Manufacturing Industry, Cem O. Onus

Walden Dissertations and Doctoral Studies

Managers at automotive manufacturers are seeking ways to reduce energy consumption, costs, carbon emissions, and waste from production processes. Researchers and practitioners perceive energy efficiency as the least expensive and most effective way to deal with issues related to climate change, but adoption of energy efficiency measures has been slow among industrial facilities. The topic of this research study was the decision-making process for energy efficiency projects in the U.S. automotive manufacturing industry. Flaws in this decision-making processes are preventing changes that can dramatically reduce energy usage, cost, and pollution. The study was grounded in the theories of energy management, …

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Transcending Technological Innovation: The Impact Of Acquisitions On Entrepreneurial Technical Organizations, Bruce Crochetiere Jan 2011

Transcending Technological Innovation: The Impact Of Acquisitions On Entrepreneurial Technical Organizations, Bruce Crochetiere

Walden Dissertations and Doctoral Studies

Technology firms with substantial cash reserves acquire smaller entrepreneurial firms for diversification. In 2006, 3 large firms acquired 28 organizations, with the combined deals exceeding {dollar}4.7 billion. The problem addressed in this study is that new start-up companies with innovative ideas may not mature when they are acquired by larger companies and do not fully articulate potential industry-transcending innovation. This is important because the unsuccessful integration of an acquisition can dismantle innovation and compromises economic inventiveness. Drawing from the disruptive innovation and the resource-based theories, the purpose of the quasi-experimental study was to examine the impact of acquisition by larger …

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Biologically Active Alkaloids From Kopsia., Yap Wai Sum Jan 2011

Biologically Active Alkaloids From Kopsia., Yap Wai Sum

Student Works (2010-2019)

Two Malaysian plants viz., Kopsia pauciflora and Kopsia grandifolia were investigated for their alkaloidal constituents. A total of 40 alkaloids were isolated and characterized from K. pauciflora, of which 12 are new alkaloids. The new alkaloids isolated include seven aspidofractinine alkaloids (1, 2, 3, 4, 5, 6, 7), and five eburnane alkaloids (8, 9, 10, 11, 12). K. grandifolia yielded a total of eight alkaloids. Of these, three are new. The new alkaloids are grandilodine A (41), grandilodine B (42), and grandilodine C (43). Grandilodine A (41), grandilodine C (43), and lapidilectine B (47) were found to reverse multidrug resistance …

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Instance-Based Parameter Tuning Via Search Trajectory Similarity Clustering, Linda Lindawati, Hoong Chuin Lau, David Lo Jan 2011

Instance-Based Parameter Tuning Via Search Trajectory Similarity Clustering, Linda Lindawati, Hoong Chuin Lau, David Lo

Research Collection School Of Computing and Information Systems

This paper is concerned with automated tuning of parameters in local-search based meta-heuristics. Several generic approaches have been introduced in the literature that returns a ”one-size-fits-all” parameter configuration for all instances. This is unsatisfactory since different instances may require the algorithm to use very different parameter configurations in order to find good solutions. There have been approaches that perform instance-based automated tuning, but they are usually problem-specific. In this paper, we propose CluPaTra, a generic (problem-independent) approach to perform parameter tuning, based on CLUstering instances with similar PAtterns according to their search TRAjectories. We propose representing a search trajectory as …

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Lightweight Delegated Subset Test With Privacy Protection, Xuhua Zhou, Xuhua Ding, Kefei Chen Jan 2011

Lightweight Delegated Subset Test With Privacy Protection, Xuhua Zhou, Xuhua Ding, Kefei Chen

Research Collection School Of Computing and Information Systems

Delegated subset tests are mandatory in many applications, such as content-based networks and outsourced text retrieval, where an untrusted server evaluates the degree of matching between two data sets. We design a novel scheme to protect the privacy of the data sets in comparison against the untrusted server, with half of the computation cost and half of the ciphertext size of existing solutions based on predicate only encryption supporting inner product.

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