Geometric Progression Method Research Articles

Novel slag/natural rubber composite as flexible material for protecting workers against radiation hazards

This work is an attempt to employ the electric arc furnace (EAF) slag as a by-product material to develop an alternative and environmentally friendly material for gamma-radiation protection applications such as in medical and industrial areas. For this purpose, different concentrations of micro-sized EAF slag (0, 20, 40, 60, 80, 100, 500, and 800 phr) were incorporated as fillers in the natural rubber (NR) matrix to produce the shielding composites. In addition, nano-sized EAF slag particles were prepared by using a high-energy ball milling technique to investigate the effect of particle size on the gamma-radiation shielding properties. The synthesized micro and nano EAF/NR composites were tested as protective materials against gamma-radiation by employing NaI(Tl) scintillation detector and standard radioactive point sources (152Eu, 137Cs, 133Ba, and 60Co). Different shielding parameters such as linear and mass attenuation coefficient, half value layer (HVL), tenth value layer, mean free path, effective atomic number (Zeff), and effective electron density (Neff) were determined to assess the radiation shielding capability of the EAF/NR composites. Furthermore, equivalent atomic number (Zeq) and the exposure buildup factor values for photon energy in the range from 0.015 to 15 MeV were also computed by Geometric Progression method. The experimental results of micro EAF/NR composites showed that at 121.78 keV, EAF0 composite (without EAF slag content) had the lowest μ value of 0.1695 cm−1, while the EAF800 composite (which was loaded with 800 phr of micro EAF slag) had the highest μ value of 0.2939 cm−1 at the same energy, which in turn decreases the HVL from 4.09 to 2.36 cm, respectively. Therefore, increasing the filler weight fractions of EAF slag in the NR matrix, increases the shielding properties of the composites. Moreover, the NR composite reinforced with 800 phr of nano EAF slag has better gamma-radiation shielding efficiency compared to that filled with 800 phr of micro EAF slag. The success of this work was to prepare a flexible, lightweight, low-cost, and lead-free material with better shielding capability.

QADCGPIC–M: A point kernel shielding code with features for handling bulk shields up to 100 mean free path and stratified shielding configurations

Salient modifications and validations performed on a Point Kernel method based code QADCGPIC, which are important for optimizing shield design is presented in the paper. The geometric progression method based build–up factors (BUFs) for penetration depths of medium up to 100 mean free path is incorporated into the modified QADCGPIC–M code. Further improvement to the code is made by incorporating the modified Kalos’ formula of double layer gamma ray exposure build–up factor (DBUF) for the shielding materials used in the design of nuclear and radiological facilities. The modified code is validated by estimating the BUFs, DBUFs, and gamma dose rates at the exit of the shield with Monte Carlo simulation for various shielding configurations of lead, tungsten, iron, and concrete and published values. The validation exercise indicates a good agreement between the computed values by different methods. The incorporation of geometric progression fitting formula and modified Kalos’ formula into the QADCGPIC–M code increases the ability of the code to handle bulk shielding and optimization of thicknesses of double layered shielding configurations.

Geant4 Simulation of Gamma-Ray Transmission Buildup Factors for Human Tissues.

Quantification of scattered photons in addition to unscattered primary particles, under realistic exposure scenario, is best dealt with a parameter called “Buildup factor”. The aim of this work is to simulate the transmission buildup factor (BUF) of gamma-ray in the energy range .15–15 MeV for 20 human tissues and organs using the Geant4 (version 10.5) Monte Carlo simulation followed by a geometrical progression (GP) parameterization procedure. Firstly, we verified the accuracy of Geant4 ability to predict the effective transmitted dose according to published data. Also, a comparison of simulated BUF for different geometrical configurations was carried out for some tissues and source energies. Then, we checked out the linear dependency of the K parameter (BUF is function of K) function of mean free path (mfp). Finally, we developed a fitting procedure according to GP method for BUF corresponding to 20 tissues and organs and different mfp (from 1 to 8) for energy range .15–15 MeV. We found a good agreement with previous published data. Proper comprehension of BUF for tissues leads to carefully controlling the energy absorption in the human body. Consequently, provided BUF could be of great interest for estimating safe dose levels in medical imaging and radiation therapy.

White and some colored marbles as alternative radiation shielding materials for applications

ABSTRACT In this paper, the radiation shielding parameters such as linear attenuation coefficients (LAC, µ), mass attenuation coefficients (MAC, µ/ρ), effective atomic numbers (Zeff), effective electron densities (Neff), half value of layers (HVL), mean free paths (MFP) and buildup factors (exposure (EBF) and energy absorption (EABF)) were investigated for cream (M1), pink (M2), white (M3), maroon (M4) and green (M5) marbles. Attenuation coefficients were measured in the energy region 31.18–661.66 keV photon energies. The values of Zeff and Neff were then calculated using these coefficients with logarithmic interpolation method, and HVLs and MFPs were calculated using the values of LAC of marble samples at the same photon energies. The experimental results were compared with the theoretical values obtained from WinXCom program, and good agreements were observed between the experimental and theoretical results. HVLs and MFPs of all marble samples were compared with those of some concretes, glasses and commercial radiation shielding glasses (SCHOTT Co.). The studied marbles were better radiation shielding materials than standard shielding concretes due to lower HVL and MFP values lower than the ordinary concrete. Finally, EBFs and EABFs of the marbles were calculated in the energy region 0.015–1 MeV up to penetration depths of 40 mfps by Geometric Progression method (G-P), and the results were discussed in terms of photon energies and chemical compositions of the marbles.

Best method of municipal solid waste management through public-private partnership for Vijayawada city

The studies are being conducted to find the best method of municipal solid waste management for Vijayawada city of A.P, as a regional inquiry that will be carried out to deal with now and upcoming years. Management of Municipal solid waste becomes the main problem nowadays in cities and municipalities like Vijayawada. From the last few years Vijayawada city faces the problem of disposal and handling of municipal solid waste. To analyze and determine the PPP model suited by executives for solid waste according to the landfill which can be modified to generate income and monitor solid waste effectively. Installation cost, land required for the proposed solid waste treatment and population are assessed by the geometrical progression method for the anticipated year 2051, waste generation in this study. To overcome the disposal and treatment of solid waste many innovations are being done in recent days. The assessed cost and land required for proposed this estimated are Rs. 320,00,000 and 4800 sqm of area approximately. The total quantity of evaluated solid waste created in the year 2051 is 2788 tons/day. This application model could reduce the cost of support for that take care of as well producing the income on model utilization. Automated module for plastic partitioning which can be tried on the public-private partnership model for Vijayawada city as best practice of solid waste.

Layout optimization for non-equidistant thrust system of tunneling machine based on geometric progression under mixed ground.

For the difference of rock and soil strength on the tunneling face, curved tunneling, and the top-heavy structure of the main machine forming the complex geological structure, the adoption of uniform thrust system arising from large unbalanced load easily causes cracks and dislocations in the rear segments. Therefore, non-equidistant driving system would be adopted in this composite foundation. This article presents a geometric progression method for layout design of non-uniform thrust system. Based on the force transmission laws of the thrust system, the geometric progression increasing difference model of arranging non-uniform driving system has been proposed. Then, the characteristics of the design method have been discussed in detail. Finally, the model has been applied to a diameter of 9.49 m of tunneling machine with a thrust system of 14 pairs of jacks which has been successfully used in curved tunnel construction in Germany. By adopting the coefficient of variation representing the force transmission performance derived from all thrusts for jacks, it indicates that the performance of the optimized thrust system is better than the original one. The results would provide a theoretical basis for the design of a non-equidistant thrust system with better force transmission performance under working geological conditions.

Radiation shielding investigations for selected tellurite-based glasses belonging to the TNW system

In this paper, we have investigated the properties of tellurite-based glass system in the form (100 -x -y)TeO2–xNbO2.5-yWO3, x = 5, 10, 15, 20, 25 mol% and y = 5 mol% for gamma and neutron shielding applications and to achieve that, mass attenuation coefficients (μm) for the selected glasses have been investigated using Geant4 toolkit and XCOM program, respectively, in the energy range between 1 keV and 10 MeV. A good agreement was observed between μm values simulated by Geant4 and those evaluated by XCOM. The obtained μm values were then utilized to derive effective atomic numbers (Zeff), mean free path (MFP), and half value layer (HVL) for the selected glasses. In addition, we used Geometric Progression method (G-P) to evaluate exposure buildup factor (EBF) values in the range of 0.015 MeV–15 MeV up to penetration depths of 40 mfp (mean free path). Among these glasses, the glass coded as TN05W05 is a superior shielding material against gamma-rays as compared with different traditional concretes, commercial glass, and HMO glasses. In addation, the fast neutron removal cross sections were calculated for the glasses involved. It is found that the present glasses offer an excellent ability for protecting against fast neutrons. Present investigation on shielding properties of the selected tellurite-based glasses would be useful for radiation protection application.

Establishment of blending control for Hand operated Double Cone Blender

In the current study, a fundamental approach is used to establish operation procedure, for a hand operated double cone blender. Initially, assuming for a potent drug, where in, the strength of the drug is very less in the final dosage form, a one percent concentration of potassium permanganate with respect to final one kilogram of blended powder using starch as diluent was planned. With a kind of geometric progression method, at a rate of 10 rotations per minute, the final outcome of the uniform distribution of the potassium permanganate was found to be for at least for fourteen hours of rotations, leading to concentration range of potassium permanganate 0.08 ± 0.025 mg per mg of final blended powder.

Attenuation coefficients and exposure buildup factor of some rocks for gamma ray shielding applications

In the present work, the mass attenuation coefficient µ/ρ is investigated experimentally and theoretically for seven rocks (olivine basalt, green marble, jet black granite, telphone black granite, cuddapah limestone, white marble and pink marble). The rock samples were collected from different places of India. The mass attenuation coefficients of the samples were measured experimentally at photon energies of radioisotopes Co57 (122 keV), Ba133 (356 keV), 22Na (511 and 1275 keV), Cs137 (662 keV), Mn54 (840 keV), and Co60 (1330 keV). Theoretically, the simulation results of µ/ρ using both XCOM and MCNP5 codes were compared with experimental results and a satisfactory agreement was observed. Total atomic cross sections (σt,a) electronic cross sections (σt,e), effective atomic number (Zeff), electron density (Ne) and half value layer (HVL) were evaluated using the obtained µ/ρ values for investigated rocks. The HVL values for the selected rocks were compared with some common shielding concretes. Moreover, by Geometric Progression method (G-P) exposure buildup factor (EBF) and energy absorption buildup factor (EABF) values were calculated for incident photon energy 0.015–15 MeV up to penetration depths of 40 mean free paths. The results show that among the studied rocks pink marble possesses superior shielding properties for γ-ray. This work was carried out to explore the advantage of utilizing the selected rocks in engineering structures and building construction to shield gamma-rays.

Shielding properties of 80TeO2–5TiO2–(15−x) WO3–xAnOm glasses using WinXCom and MCNP5 code

Gamma ray shielding properties of 80TeO2–5TiO2–(15−x) WO3–xAnOm glasses, where AnOm is Nb2O5 = 0.01, 5, Nd2O3 = 3, 5 and Er2O3 = 5mol% have been achieved. Shielding parameters; mass attenuation coefficients, half value layers, and macroscopic effective removal cross section for fast neutrons have been computed by using WinXCom program and MCNP5 Monte Carlo code. In addition, by using Geometric Progression method (G-P), exposure buildup factor values were also calculated. Variations of shielding parameters are discussed for the effect of REO addition into the glasses and photon energy.

X-ray photoelectron spectroscopy (XPS) and radiation shielding parameters investigations for zinc molybdenum borotellurite glasses containing different network modifiers

Zinc molybdenum borotellurite glasses containing different network modifiers with the nominal composition of 60 TeO2–10 B2O3–10 MoO3–10 ZnO–10 MO (MO = Li2O, Na2O, K2O, MgO, CaO, and PbO) were prepared by melt quenching method. The X-ray photoelectron spectroscopy (XPS) studies allow to monitor the structural modifications leading to the formation of bridging oxygens (Te–O–Te, B–O–B, Mo–O–Mo, and Te–O–Mo bonds) and nonbridging oxygens (Te = O, Te–O−M+, Mo–O− bonds in the MoO6 octahedral units, Zn–O bonds from ZnO4) with the addition of alkali (Li, Na, and K), alkaline (Mg, Ca), or heavy metal (Pb) oxides. The Te 3d localized core-levels spectra show an asymmetry due to the existence of different Te-based structural clusters and were fitted with three contributions such as Te ions in TeO4 trigonal bipyramid configuration, Te ions in TeO3 − trigonal pyramid configuration and TeO3+1 polyhedra, respectively. The analysis of the Mo 3d spectra indicates prevailingly Mo6+ ions only. The Zn 2p core-level XPS spectra demonstrate that the zinc is mainly coordinated by four oxygen atoms. The essential radiation shielding parameters were studied for the prepared glasses in the photon energy range 1 keV to 100 GeV using WinXCom software program. Parameters like mass attenuation coefficient (μ/ρ), effective atomic number (Z eff), and mean free path (MFP) are evaluated. Further, by using geometric progression method, exposure buildup factor (EBF) values were also calculated in the incident photon energy range 0.015–15 MeV, up to penetration depth of 40 mfp (mean free path). The macroscopic effective removal cross sections (∑R) for fast neutrons have been calculated. The maximum values of μ/ρ and Z eff were found for PbO-introduced glass though it possesses a lower value for MFP and EBF. The obtained results indicate that PbO-based glass is the best radiation shielding material among the studied glasses.

Gamma-ray shielding properties of zinc oxide soda lime silica glasses

In the present work, the gamma ray shielding properties of zinc oxide soda lime silica, (ZnO)x(SLS)1−x glasses with 0 ≥ x ≥ 50 wt% have been investigated. By using WinXCom computer software, the mass attenuation coefficient (µ/ρ) and half value layer (HVL) for total photon interaction in the energy range of 1 keV–100 GeV were calculated. Furthermore and by Geometric Progression method exposure buildup factor values were calculated for incident photon energy 0.015–15 MeV up to penetration depths of 40 mfp (mean free path). The addition of zinc oxide (ZnO) into soda lime silica (SLS) glass resulted in an increase the mass attenuation coefficient and decreases both the half value layer and exposure buildup factor. The obtained results of the selected glass series have been compared, in terms of mass attenuation coefficient, half value layer and exposure buildup factor with some common shielding materials. The shielding effectiveness of the selected glasses is found comparable to that of common ones; which indicates that the SLS glasses with suitable ZnO content may be developed as gamma ray shielding materials.

Half value layer, mean free path and exposure buildup factor for tellurite glasses with different oxide compositions

The half value layer (HVL) and mean free path (MFP) of tellurite glasses with different forming oxides (BaO, ZnO, Nb2O5, Ag2O, MgO and PbO) have been calculated using WinXCom program in order to examine their possibility for utilization as radiation shielding glasses. Furthermore, Geometric Progression method (G-P) has been used to calculate exposure buildup factor (EBF) values for incident photon energy 0.015 MeV–15 MeV up to penetration depths of 40 mfp (mean free path). It has been found that TeO2-PbO glass has the minimum HVL and MFP; hence it possesses excellent shielding capability against gamma radiation. The obtained results of the selected glass series have been compared, in terms of MFP with seven types of concretes. The shielding effectiveness of the selected glasses is found better to that of concretes. The obtained results in this work show that these glasses may be potential candidates for radiation shielding applications.

Gamma-ray and neutron shielding efficiency of Pb-free gadolinium-based glasses

The radiation shielding efficiency of material depends upon photon attenuation, exposure buildup factors and neutron removal capacity. A newly developed Pb-free gadolinium-based glasses in compositions (80-x) B2O3-10SiO2-10CaO-xGd2O3 (where x = 15, 20, 25, 30 and 35 mol%) had completely been investigated for their shielding efficiency with Geant4 simulation for mass attenuation coefficients and neutron total macroscopic cross section and by calculating exposure buildup factors. The exposure buildup factors for photon energy from 0.015 to 15 MeV had been calculated up to 40 mean free paths using five factors geometric progression method. The mass attenuation coefficients of the Pb-free glasses were simulated for energies from 223 to 2614 keV and compared with the possible available experimental results. The neutron shielding efficiency of these glasses was discussed by calculating neutron total macroscopic cross section for energies from 1 eV to 14.1 MeV. Present investigations are found to be very useful for applications in nuclear engineering.

A Sector Based Energy Efficient Adaptive Routing Protocol for Large Scale MANET

A MANET is a type of ad-hoc network that can change locations and configure itself on the fly. A MANET involves mobile platforms which are free to move arbitrarily and there may be frequent link breakage due to battery. We propose a novel adhoc routing protocol named as Sector based Energy Efficient (SEA) routing protocol with high data throughput. To overcome the link breakage in MANET, the proposed protocol also uses the mathematical geometrical progression method, which minimizes the redundancy distance calculation and routing overhead. We also combine the mathematical model with weight based route estimation techniques. It selects the longest life span to estimate the route stability derived from received signal strength. The simulation results shows that the proposed SEA protocol yields better performance then the existing protocols namely EDRP, EDNR, DOA and AODV in terms of packet delivery ratio and energy consumption.

Gamma-Ray Shielding Effectiveness of Some Alloys for Fusion Reactor Design

The gamma-ray shielding effectiveness of some oxide dispersion-strengthen (ODS) alloys by means of mass attenuation coefficients, mean free path, exposure buildup factors and energy absorption buildup factors have been investigated in the present study. The buildup factors were calculated using geometrical progression method for photon energy 0.015–15 MeV up to 40 mfp penetration depth. The mass attenuation coefficients were calculated by using XCOM program and Geant4 simulation methods and found a very good agreement. Our investigation signifies that the low iron content ODS alloys are superior shielding materials with the lower buildup factors. This study should be useful for selection of shielding materials for their applications in fusion reactors design and future nuclear reactor technologies.

Kinematic characteristics and the influence of reference velocities of phase‐shift‐plus‐interpolation and extended‐split‐step‐Fourier migration methods

ABSTRACTThe phase‐shift‐plus‐interpolation and extended‐split‐step‐Fourier methods are wavefield‐continuation algorithms for seismic migration imaging. These two methods can be applied to regions with complex geological structures. Based on their unified separable formulas, we show that these two methods have the same kinematic characteristics by using the theory of pseudodifferential operators. Numerical tests on a Marmousi model demonstrate this conclusion. Another important aspect of these two methods is the selection of reference velocities and we explore the influence of the selection of reference velocities by comparing the geometric progression method and the statistical method. We show that the geometric progression method is simple but does not take into account the velocity distribution while the statistical approach is relatively complex but reflects the velocity distribution.