Search results for: gamma prime phase
Commenced in January 2007
Frequency: Monthly
Edition: International
Paper Count: 1844

Search results for: gamma prime phase

1844 The High Temperature Damage of DV – 2 Turbine Blade Made from Ni – Base Superalloy

Authors: Juraj Belan, Lenka Hurtalová, Eva Tillová, Alan Vaško, Milan Uhríčik

Abstract:

High pressure turbine (HPT) blades of DV – 2 jet engines are made from Ni – based superalloy. This alloy was originally manufactured in the Soviet Union and referred as ŽS6K. For improving alloy’s high temperature resistance are blades coated with Al – Si diffusion layer. A regular operation temperature of HPT blades vary from 705°C to 750°C depending on jet engine regime. An overcrossing working temperature range causes degradation of the protective coating as well as base material which microstructure is formed by the gamma matrix and strengthening phase gamma prime (forming small particles in the microstructure). Diffusion processes inside the material during exposition of the material to high temperatures causes mainly coarsening of the gamma prime particles, thus decreasing its strengthening effect. Degradation of the Al – Si coating caused its thickness growth. All the microstructure changes and coating layer thickness growth results in decreasing of the turbine blade operation lifetime.

Keywords: Alitize coating layer, gamma prime phase, high temperature degradation, Ni – base superalloy ŽS6K, turbine blade.

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1843 (R, S)-Modules and (1, k)-Jointly Prime (R, S)-Submodules

Authors: Thawatchai Khumprapussorn

Abstract:

We introduced the notions of (1, k)-prime ideal and (1, k)-jointly prime (R, S)-submodule as a generalization of prime ideal and jointly prime (R, S)-submodule, respectively. We provide a relationship between (1, k)-prime ideal and (1, k)-jointly prime (R, S)-submodule. Characterizations of (1, k)-jointly prime (R, S)- submodules are also given.

Keywords: R, S)-module, (1, k)-prime ideal, (1, k)-jointly prime (R, S)-submodule.

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1842 A Post Processing Method for Quantum Prime Factorization Algorithm based on Randomized Approach

Authors: Mir Shahriar Emami, Mohammad Reza Meybodi

Abstract:

Prime Factorization based on Quantum approach in two phases has been performed. The first phase has been achieved at Quantum computer and the second phase has been achieved at the classic computer (Post Processing). At the second phase the goal is to estimate the period r of equation xrN ≡ 1 and to find the prime factors of the composite integer N in classic computer. In this paper we present a method based on Randomized Approach for estimation the period r with a satisfactory probability and the composite integer N will be factorized therefore with the Randomized Approach even the gesture of the period is not exactly the real period at least we can find one of the prime factors of composite N. Finally we present some important points for designing an Emulator for Quantum Computer Simulation.

Keywords: Quantum Prime Factorization, RandomizedAlgorithms, Quantum Computer Simulation, Quantum Computation.

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1841 On Properties of Generalized Bi-Γ-Ideals of Γ-Semirings

Authors: Teerayut Chomchuen, Aiyared Iampan

Abstract:

The notion of Γ-semirings was introduced by Murali Krishna Rao as a generalization of the notion of Γ-rings as well as of semirings. We have known that the notion of Γ-semirings is a generalization of the notion of semirings. In this paper, extending Kaushik, Moin and Khan’s work, we generalize the notion of generalized bi-Γ-ideals of Γ-semirings and investigate some related properties of generalized bi-Γ-ideals.

Keywords: Γ-semiring, bi-Γ-ideal, generalized bi-Γ-ideal.

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1840 Phase Transition Characteristics of Flame-Synthesized Gamma-Al2O3 Nanoparticles with Heat Treatment

Authors: Gyo Woo Lee

Abstract:

In this study, the phase transition characteristics of flame-synthesized γ-Al2O3 nanoparticles to α-Al2O3 have been investigated. The nanoparticles were synthesized by using a coflow hydrogen diffusion flame. The phase transition and particle characteristics of the Al2O3 nanoparticles were determined by examining the crystalline structure and the shape of the collected nanoparticles before and after the heat treatment. The morphology and crystal structure of the Al2O3 nanoparticles were determined from SEM images and XRD analyses, respectively. The measured specific surface area and averaged particle size were 63.44m2/g and 23.94nm, respectively. Based on the scanning electron microscope images and x-ray diffraction patterns, it is believed that the onset temperature of the phase transition to α-Al2O3 was existed near 1200oC. The averaged diameters of the sintered particles heat treated at 1,260oC were approximately 80nm.

Keywords: BET Specific Surface Area, Gamma-Al2O3 Nanoparticles, Flame Synthesis, Phase Transition, X-ray Diffraction.

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1839 The Baer Radical of Rings in Term of Prime and Semiprime Generalized Bi-ideals

Authors: Rattiya Boonruang, Aiyared Iampan

Abstract:

Using the idea of prime and semiprime bi-ideals of rings, the concept of prime and semiprime generalized bi-ideals of rings is introduced, which is an extension of the concept of prime and semiprime bi-ideals of rings and some interesting characterizations of prime and semiprime generalized bi-ideals are obtained. Also, we give the relationship between the Baer radical and prime and semiprime generalized bi-ideals of rings in the same way as of biideals of rings which was studied by Roux.

Keywords: ring, prime and semiprime (generalized) bi-ideal, Baer radical.

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1838 Quadratic Irrationals, Quadratic Ideals and Indefinite Quadratic Forms II

Authors: Ahmet Tekcan, Arzu Özkoç

Abstract:

Let D = 1 be a positive non-square integer and let δ = √D or 1+√D 2 be a real quadratic irrational with trace t =δ + δ and norm n = δδ. Let γ = P+δ Q be a quadratic irrational for positive integers P and Q. Given a quadratic irrational γ, there exist a quadratic ideal Iγ = [Q, δ + P] and an indefinite quadratic form Fγ(x, y) = Q(x−γy)(x−γy) of discriminant Δ = t 2−4n. In the first section, we give some preliminaries form binary quadratic forms, quadratic irrationals and quadratic ideals. In the second section, we obtain some results on γ, Iγ and Fγ for some specific values of Q and P.

Keywords: Quadratic irrationals, quadratic ideals, indefinite quadratic forms, extended modular group.

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1837 Development of a Nano-Alumina-Zirconia Composite Catalyst as an Active Thin Film in Biodiesel Production

Authors: N. Marzban, J. K. Heydarzadeh M. Pourmohammadbagher, M. H. Hatami, A. Samia

Abstract:

A nano-alumina-zirconia composite catalyst was synthesized by a simple aqueous sol-gel method using AlCl3.6H2O and ZrCl4 as precursors. Thermal decomposition of the precursor and subsequent formation of γ-Al2O3 and t-Zr were investigated by thermal analysis. XRD analysis showed that γ-Al2O3 and t-ZrO2 phases were formed at 700 °C. FT-IR analysis also indicated that the phase transition to γ-Al2O3 occurred in corroboration with X-ray studies. TEM analysis of the calcined powder revealed that spherical particles were in the range of 8-12 nm. The nano-alumina-zirconia composite particles were mesoporous and uniformly distributed in their crystalline phase. In order to measure the catalytic activity, esterification reaction was carried out. Biodiesel, as a renewable fuel, was formed in a continuous packed column reactor. Free fatty acid (FFA) was esterified with ethanol in a heterogeneous catalytic reactor. It was found that the synthesized γ-Al2O3/ZrO2 composite had the potential to be used as a heterogeneous base catalyst for biodiesel production processes.

Keywords: Nano-alumina-zirconia, composite catalyst, thin film, biodiesel.

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1836 On Weakly Prime and Weakly Quasi-Prime Fuzzy Left Ideals in Ordered Semigroups

Authors: Jian Tang

Abstract:

In this paper, we first introduce the concepts of weakly prime and weakly quasi-prime fuzzy left ideals of an ordered semigroup S. Furthermore, we give some characterizations of weakly prime and weakly quasi-prime fuzzy left ideals of an ordered semigroup S by the ordered fuzzy points and fuzzy subsets of S.

Keywords: Ordered semigroup, ordered fuzzy point, weakly prime fuzzy left ideal, weakly quasi-prime fuzzy left ideal.

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1835 Impact of Weather Conditions on Generalized Frequency Division Multiplexing over Gamma Gamma Channel

Authors: Muhammad Sameer Ahmed, Piotr Remlein, Tansal Gucluoglu

Abstract:

The technique called as Generalized frequency division multiplexing (GFDM) used in the free space optical channel can be a good option for implementation free space optical communication systems. This technique has several strengths e.g. good spectral efficiency, low peak-to-average power ratio (PAPR), adaptability and low co-channel interference. In this paper, the impact of weather conditions such as haze, rain and fog on GFDM over the gamma-gamma channel model is discussed. A Trade off between link distance and system performance under intense weather conditions is also analysed. The symbol error probability (SEP) of GFDM over the gamma-gamma turbulence channel is derived and verified with the computer simulations.

Keywords: Free space optics, generalized frequency division multiplexing, weather conditions, gamma gamma distribution.

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1834 The Effects of Electromagnetic Stirring on Microstructure and Properties of γ-TiAl Based Alloys Fabricated by Selective Laser Melting Technique

Authors: A. Ismaeel, C. S. Wang, D. S. Xu

Abstract:

The γ-TiAl based Ti-Al-Mn-Nb alloys were fabricated by selective laser melting (SLM) on the TC4 substrate. The microstructures of the alloys were investigated in detail. The results reveal that the alloy without electromagnetic stirring (EMS) consists of γ-TiAl phase with tetragonal structure and α2-Ti3Al phase with hcp structure, while the alloy with applied EMS consists of γ-TiAl, α2-Ti3Al and α-Ti with hcp structure, and the morphological structure of the alloy without EMS which exhibits near lamellar structure and the alloy with EMS shows duplex structure, the alloy without EMS shows some microcracks and pores while they are not observed in the alloy without EMS. The microhardness and wear resistance values decrease with applied EMS.

Keywords: Selective laser melting, γ-TiAl based alloys, microstructure, properties, electromagnetic stirring.

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1833 Prime(Semiprime) Fuzzy h-ideal in Γ-hemiring

Authors: Sujit Kumar Sardar, Debabrata Mandal

Abstract:

The notions of prime(semiprime) fuzzy h-ideal(h-biideal, h-quasi-ideal) in Γ-hemiring are introduced and some of their characterizations are obtained by using "belongingness(∈)" and "quasi - coincidence(q)". Cartesian product of prime(semiprime) fuzzy h-ideals of Γ-hemirings are also investigated.

Keywords: Γ-hemiring, Fuzzy h-ideals, Prime fuzzy left h-ideal, Prime(semiprime) (∈, ∈ ∨q)-fuzzy left h-bi-ideal(h-ideal, h-quasiideal), Cartesian product

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1832 Formation of Protective Silicide-Aluminide Coating on Gamma-TiAl Advanced Material

Authors: S. Nouri

Abstract:

In this study, the Si-aluminide coating was prepared on gamma-TiAl [Ti-45Al-2Nb-2Mn-1B (at. %)] via liquid-phase slurry procedure. The high temperature oxidation resistance of this diffusion coating was evaluated at 1100 °C for 400 hours. The results of the isothermal oxidation showed that the formation of Si-aluminide coating can remarkably improve the high temperature oxidation of bare gamma-TiAl alloy. The identification of oxide scale microstructure showed that the formation of protective Al2O3+SiO2 mixed oxide scale along with a continuous, compact and uniform layer of Ti5Si3 beneath the surface oxide scale can act as an oxygen diffusion barrier during the high temperature oxidation. The other possible mechanisms related to the formation of Si-aluminide coating and oxide scales were also discussed.

Keywords: Gamma-TiAl alloy, Si-aluminide coating, slurry procedure, high temperature oxidation.

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1831 Prime Cordial Labeling on Graphs

Authors: S. Babitha, J. Baskar Babujee

Abstract:

A prime cordial labeling of a graph G with vertex set V is a bijection f from V to {1, 2, ..., |V |} such that each edge uv is assigned the label 1 if gcd(f(u), f(v)) = 1 and 0 if gcd(f(u), f(v)) > 1, then the number of edges labeled with 0 and the number of edges labeled with 1 differ by at most 1. In this paper we exhibit some characterization results and new constructions on prime cordial graphs.

Keywords: Prime cordial, tree, Euler, bijective, function.

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1830 Gamma Irradiation Effects on the Magnetic Properties of Hard Ferrites

Authors: F. Abbas Pour Khotbehsara, B. Salehpour, A. Kianvash

Abstract:

Many industrial materials like magnets need to be tested for the radiation environment expected at linear colliders (LC) where the accelerator and detectors will be subjected to large influences of beta, neutron and gamma’s over their life Gamma irradiation of the permanent sample magnets using a 60Co source was investigated up to an absorbed dose of 700Mrad shows a negligible effect on some magnetic properties of Nd-Fe-B. In this work it has been tried to investigate the change of some important properties of Barium hexa ferrite. Results showed little decreases of magnetic properties at doses rang of 0.5 to 2.5 Mrad. But at the gamma irradiation dose up to 10 Mrad it is showed a few increase of properties. Also study of gamma irradiation of Nd-Fe-B showed considerably increase of magnetic properties.

Keywords: Gamma ray irradiation, Hard Ferrite, Magnetic coefficient, Radiation dose.

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1829 Gamma Irradiation Effect on Structural and Optical Properties of Bismuth-Boro-Tellurite Glasses

Authors: A. Azuraida, M. K. Halimah, C. A. C. Azurahanim, M. Ishak

Abstract:

The changes of the optical and structural properties of Bismuth-Boro-Tellurite glasses pre and post gamma irradiation were studied. Six glass samples, with different composition [(TeO2)0.7 (B2O3)0.3]1-x (Bi2O3)x prepared by melt quenching method were irradiated with 25kGy gamma radiation at room temperature. The Fourier Transform Infrared Spectroscopy (FTIR) was used to explore the structural bonding in the prepared glass samples due to exposure, while UV-VIS Spectrophotometer was used to evaluate the changes in the optical properties before and after irradiation. Gamma irradiation causes profound changes in the peak intensity as shown by FTIR spectra which is due to the breaking of the network bonding. Before gamma irradiation, the optical band gap, Eg value decreased from 2.44 eV to 2.15 eV with the addition of Bismuth content. The value kept decreasing (from 2.18 eV to 2.00 eV) following exposure to gamma radiation due to the increase of non-bridging oxygen (NBO) and the increase of defect in the glass. In conclusion, the glass with high content of Bi2O3 (0.30Bi) give smallest Eg and show less changes in FTIR spectra after gamma irradiation which indicate that this glass is more resistant to gamma radiation compared to other glasses.

Keywords: Boro-Tellurite, bismuth, gamma radiation, optical properties.

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1828 Pythagorean-Platonic Lattice Method for Finding all Co-Prime Right Angle Triangles

Authors: Anthony Overmars, Sitalakshmi Venkatraman

Abstract:

This paper presents a method for determining all of the co-prime right angle triangles in the Euclidean field by looking at the intersection of the Pythagorean and Platonic right angle triangles and the corresponding lattice that this produces. The co-prime properties of each lattice point representing a unique right angle triangle are then considered. This paper proposes a conjunction between these two ancient disparaging theorists. This work has wide applications in information security where cryptography involves improved ways of finding tuples of prime numbers for secure communication systems. In particular, this paper has direct impact in enhancing the encryption and decryption algorithms in cryptography.

Keywords: Pythagorean triples, platonic triples, right angle triangles, co-prime numbers, cryptography.

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1827 On Q-Fuzzy Ideals in Γ-Semigroups

Authors: Samit Kumar Majumder

Abstract:

In this paper the concept of Q-fuzzification of ideals of Γ-semigroups has been introduced and some important properties have been investigated. A characterization of regular Γ-semigroup in terms of Q-fuzzy ideals has been obtained. Operator semigroups of a Γ-semigroup has been made to work by obtaining various relationships between Q-fuzzy ideals of a Γ-semigroup and that of its operator semigroups.

Keywords: Q-Fuzzy set, Γ-semigroup, Regular Γ-semigroup, Q-Fuzzy left(right) ideal, Operator semigroups.

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1826 A Mixture Model of Two Different Distributions Approach to the Analysis of Heterogeneous Survival Data

Authors: Ülkü Erişoğlu, Murat Erişoğlu, Hamza Erol

Abstract:

In this paper we propose a mixture of two different distributions such as Exponential-Gamma, Exponential-Weibull and Gamma-Weibull to model heterogeneous survival data. Various properties of the proposed mixture of two different distributions are discussed. Maximum likelihood estimations of the parameters are obtained by using the EM algorithm. Illustrative example based on real data are also given.

Keywords: Exponential-Gamma, Exponential-Weibull, Gamma-Weibull, EM Algorithm, Survival Analysis.

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1825 Effects of Gamma Irradiation on Chemical and Antioxidant Properties of Iranian Native Fresh Barberry Fruit

Authors: Samira Berenji Ardestani, Hamid Reza Akhavan

Abstract:

Gamma irradiation greatly reduces the potential microbiological risk of fresh fruits, resulting in improved microbial safety as well as extending their shelf life. The effects of 0.5-2 kGy gamma doses on some physicochemical, microbial and sensory properties of fresh barberry fruits (Berberis vulgaris) during refrigerated storage for 40 days were evaluated. The total anthocyanin and total phenolic contents of barberry fruits decreased in a dose-dependent manner immediately after irradiation and after subsequent storage. In general, it is recommended that, according to the effect of gamma radiation on physicochemical, microbial and sensorial characteristics, doses of 1.25-2 kGy could be used.

Keywords: Antioxidant property, barberry fruit, chemical properties, gamma irradiation.

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1824 Effect of Gamma Irradiation on Structural and Optical Properties of ZnO/Mesoporous Silica Nanocomposite

Authors: K. Sowri Babu, P. Srinath, N. Rajeswara Rao, K. Venugopal Reddy

Abstract:

The effect of gamma ray irradiation on morphology and optical properties of ZnO/Mesoporous silica (MPS) nanocomposite was studied. The ZnO/MPS nanocomposite was irradiated with gamma rays of doses 30, 60, and 90 kGy and dose-rate of irradiation was 0.15 kGy/hour. Irradiated samples are characterized with FE-SEM, FT-IR, UV-vis, and Photoluminescence (PL) spectrometers. SEM pictures showed that morphology changed from spherical to flake like morphology. UV-vis analysis showed that the band gap increased with increase of gamma ray irradiation dose. This enhancement of the band gap is assigned to the depletion of oxygen vacancies with irradiation. The intensity of PL peak decreased gradually with increase of gamma ray irradiation dose. The decrease in PL intensity is attributed to the decrease of oxygen vacancies at the interface due to poor interface and improper passivation between ZnO/MPS.

Keywords: ZnO nanoparticles, photoluminescence, porous silicon, nanocomposites.

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1823 Statistical Analysis of Interferon-γ for the Effectiveness of an Anti-Tuberculous Treatment

Authors: Shishen Xie, Yingda L. Xie

Abstract:

Tuberculosis (TB) is a potentially serious infectious disease that remains a health concern. The Interferon Gamma Release Assay (IGRA) is a blood test to find out if an individual is tuberculous positive or negative. This study applies statistical analysis to the clinical data of interferon-gamma levels of seventy-three subjects who diagnosed pulmonary TB in an anti-tuberculous treatment. Data analysis is performed to determine if there is a significant decline in interferon-gamma levels for the subjects during a period of six months, and to infer if the anti-tuberculous treatment is effective.

Keywords: Data analysis, interferon gamma release assay, statistical methods, tuberculosis infection.

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1822 Dosimetric Comparison of aSi1000 EPID and ImatriXX 2-D Array System for Volumetric Modulated Arc and Intensity Modulated Radiotherapy Patient Specific Quality Assurance

Authors: Jayesh K., Ganesh T., Suganthi D., Mohan R., Rakesh C. J., Sarojkumar D. M., Jacob S. J.

Abstract:

Prior to the use of detectors, characteristics comparison study was performed and baseline established. In patient specific QA, the portal dosimetry mean values of area gamma, average gamma and maximum gamma were 1.02, 0.31 and 1.31 with standard deviation of 0.33, 0.03 and 0.14 for IMRT and the corresponding values were 1.58, 0.48 and 1.73 with standard deviation of 0.31, 0.06 and 0.66 for VMAT. With ImatriXX 2-D array system, on an average 99.35% of the pixels passed the criteria of 3%-3 mm gamma with standard deviation of 0.24 for dynamic IMRT. For VMAT, the average value was 98.16% with a standard deviation of 0.86. The results showed that both the systems can be used in patient specific QA measurements for IMRT and VMAT. The values obtained with the portal dosimetry system were found to be relatively more consistent compared to those obtained with ImatriXX 2-D array system.

Keywords: Gamma, IMRT, QA, TPS, VMAT.

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1821 Preliminary Geophysical Assessment of Soil Contaminants around Wacot Rice Factory Argungu, North-Western Nigeria

Authors: A. I. Augie, Y. Alhassan, U. Z. Magawata

Abstract:

Geophysical investigation was carried out at wacot rice factory Argungu north-western Nigeria, using the 2D electrical resistivity method. The area falls between latitude 12˚44′23ʺN to 12˚44′50ʺN and longitude 4032′18′′E to 4032′39′′E covering a total area of about 1.85 km. Two profiles were carried out with Wenner configuration using resistivity meter (Ohmega). The data obtained from the study area were modeled using RES2DIVN software which gave an automatic interpretation of the apparent resistivity data. The inverse resistivity models of the profiles show the high resistivity values ranging from 208 Ωm to 651 Ωm. These high resistivity values in the overburden were due to dryness and compactness of the strata that lead to consolidation, which is an indication that the area is free from leachate contaminations. However, from the inverse model, there are regions of low resistivity values (1 Ωm to 18 Ωm), these zones were observed and identified as clayey and the most contaminated zones. The regions of low resistivity thereby indicated the leachate plume or the highly leachate concentrated zones due to similar resistivity values in both clayey and leachate. The regions of leachate are mainly from the factory into the surrounding area and its groundwater. The maximum leachate infiltration was found at depths 1 m to 15.9 m (P1) and 6 m to 15.9 m (P2) vertically, as well as distance along the profiles from 67 m to 75 m (P1), 155 m to 180 m (P1), and 115 m to 192 m (P2) laterally.

Keywords: Contaminant, leachate, soil, groundwater, 2D, electrical, resistivity, Argungu.

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1820 Survey Gamma Radiation Measurements in Commercially-used Natural Tiling Rocks in Iran

Authors: A.Abbasi, F.Mirekhtiary

Abstract:

The gamma radiation in samples of a variety of natural tiling rocks (granites) produced and imported in Iran use in the building industry was measured, employing high-resolution Gamma-ray spectroscopy. The rock samples were pulverized, sealed in 0.5 liter plastic Marinelli beakers, and measured in the laboratory with an accumulating time between 50000 and 80000 second each. From the measured Gamma-ray spectra, activity concentrations were determined for 232Th (range from 6.5 to 172.2 Bq kg-1), 238U (from 7.5 to 178.1 Bq kg-1 ),226Ra( from 3.8 to 94.2 Bq kg-1 ) 40K (from 556.9 to 1539.2 Bq kg-1). From the 29 samples measured in this study, “Nehbndan ( Berjand )" appears to present the highest concentrations for 232Th,“Big Red Flower (China) "for 238U , “ Khoram dareh" for 226 Ra and “ Peranshahr" for 40K , respectively.

Keywords: activity concentration, natural radioactivity, tilingrocks (granites)

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1819 Performance Analysis of a Hybrid DF-AF Hybrid RF/FSO System under Gamma Gamma Atmospheric Turbulence Channel Using MPPM Modulation

Authors: Hechmi Saidi, Noureddine Hamdi

Abstract:

The performance of hybrid amplify and forward - decode and forward (AF-DF) hybrid radio frequency/free space optical (RF/FSO) communication system, that adopts M-ary pulse position modulation (MPPM) techniques, is analyzed. Both exact and approximate symbol-error rates (SERs) are derived. The random variations of the received optical irradiance, produced by the atmospheric turbulence, is modeled by the gamma-gamma (GG) statistical distribution. A closed-form expression for the probability density function (PDF) is derived for the whole above system is obtained. Thanks to the use of hybrid AF-DF hybrid RF/FSO configuration and MPPM, the effects of atmospheric turbulence is mitigated; hence the capacity of combating atmospheric turbulence and the transmissitted signal quality are improved.

Keywords: FSO, RF, hybrid, AF, DF, SER, SNR, GG channel.

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1818 Performance Analysis of a Free-Space Optical Code Division Multiple Access through Atmospheric Turbulence Channel

Authors: Tanveer Ahmed Bhuiyan, Samiul Hayder Choudhury, Asif Al - Rasheed, S.P. Majumder

Abstract:

In this paper, the effect of atmospheric turbulence on bit error probability in free-space optical CDMA scheme with Sequence Inverse Keyed (SIK) optical correlator receiver is analyzed. Here Intensity Modulation scheme is considered for transmission. The turbulence induced fading is described by the newly introduced gamma-gamma pdf[1] as a tractable mathematical model for atmospheric turbulence. Results are evaluated with Gold and Kasami code & it is shown that Gold sequence can be used for more efficient transmission than Kasami sequence in an atmospheric turbulence channel.

Keywords: CDMA, gamma-gamma pdf, atmospheric turbulence, Kasami, Gold, SIK, BER, Power Penalty, FSO.

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1817 Analysis of Gamma-Ray Spectra Using Levenberg-Marquardt Method

Authors: A. H. Fatah, A. H. Ahmed

Abstract:

Levenberg-Marquardt method (LM) was proposed to be applied as a non-linear least-square fitting in the analysis of a natural gamma-ray spectrum that was taken by the Hp (Ge) detector. The Gaussian function that composed of three components, main Gaussian, a step background function and tailing function in the lowenergy side, has been suggested to describe each of the y-ray lines mathematically in the spectrum. The whole spectrum has been analyzed by determining the energy and relative intensity for the strong y-ray lines.

Keywords: Gamma-Ray, Spectrum analysis, Non-linear leastsquare fitting.

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1816 Lattice Boltzmann Simulation of MHD Natural Convection in a Nanofluid-Filled Enclosure with Non-Uniform Heating on Both Side Walls

Authors: Imen Mejri, Ahmed Mahmoudi, Mohamed A. Abbassi, Ahmed Omri

Abstract:

This paper examines the natural convection in a square enclosure filled with a water-Al2O3 nanofluid and is subjected to a magnetic field. The side walls of the cavity have spatially varying sinusoidal temperature distributions. The horizontal walls are adiabatic. Lattice Boltzmann method (LBM) is applied to solve the coupled equations of flow and temperature fields. This study has been carried out for the pertinent parameters in the following ranges: Rayleigh number of the base fluid, Ra=103 to 106, Hartmann number varied from Ha=0 to 90, phase deviation (γ=0, π/4, π/2, 3π/4 and π) and the solid volume fraction of the nanoparticles between Ø = 0 and 6%. The results show that the heat transfer rate increases with an increase of the Rayleigh number but it decreases with an increase of the Hartmann number. For γ=π/2 and Ra=105 the magnetic field augments the effect of nanoparticles. At Ha=0, the greatest effects of nanoparticles are obtained at γ = 0 and π/4 for Ra=104 and 105 respectively.

 

Keywords: Lattice Boltzmann Method, magnetic field, Natural convection, nanofluid, Sinusoidal temperature distribution.

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1815 Estimation of Crustal Thickness within the Sokoto Basin North-Western Nigeria Using Bouguer Gravity Anomaly Data

Authors: T. T. Olugbenga, A. I. Augie

Abstract:

This research proposes an interpretation of the Bouguer’ gravity anomaly data of some parts of Sokoto basin for the estimation of crustal thickness. The study area is bounded between latitudes 1100′0″N and 1300′0″N, and longitudes 400′0″E and 600′0″E that covered Koko, Jega, B/Kebbi, Argungu, Lema, Bodinga, Tamgaza, Gunmi,Daki Takwas, Dange, Sokoto, Ilella, T/Mafara, Anka, Maru, Gusau, K/Namoda, and Sabon Birni within Sokoto, Kebbi and Zamfara state respectively. The established map of the study area was digitized in X, Y and Z format using excel software package and the digitized data were processed using Surfer version 13 software. The Moho and Conrad depths based on a relationship between Bouguer’ gravity anomaly determined crustal thickness were estimated as 35 to 37 km and 19 to 21 km, respectively. The crustal region has been categorized into: Crustal thinning zone that is the region with high gravity anomaly value due to its greater geothermal energy and also Crustal thickening zone which the region with low anomaly values due to its lower geothermal energy. Birnin kebbi, Jega, Sokoto were identified as the region of hydrocarbon potential with an estimate of 35 km thickness within the crustal region which is referred to as crustal thickening as a result of its low but sufficient geothermal energy to decompose organic matter within the region to form hydrocarbons.

Keywords: Bouguer gravity anomaly, crustal thickness, geothermal energy, hydrocarbons, Moho and Conrad Depths.

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