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Assessment of Primordial Radionuclides in Pakistani Red Bricks and Associated Radiation Doses

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Chinese Physics Letters 2010年第3期27卷 343-346页

作者： K. Khan A. Jabbar P. akhter m. Tufail H. m. Khan Health Physics Division PINSTECH P.O. Box 1482 Nilore Islamabad Pakistan Pakistan Institute of Engineering and Applied Sciences P.O. Nilore Islamabad Pakistan National Centre of Excellence in Physical Chemistry University of Peshawar Pakistan

Specific activity of primordial radionuclides and associated radiation hazards due to 40K, 226Ra, and 232Th have been measured in backed red brick samples, collected from five highly populated areas of the North west Frontier Province of Pakistan. For the detection, analysis and data acquisition, a high purity germanium detector was used. Associated external doses were calculated using a monte Carlo neutron photon transport code. A theoretical model to determine the gamma dose rate at 1 m height from the floor, made of bricks, was employed for the calculation of mass attenuation coefficient and self-absorption in the floor for the gamma energies of these radionuclides and their progeny. monte Carlo simulation shows that in this study the floor, having more than an effective thickness of 15 cm, contributes very little to the external gamma dose rate. The values of the external dose rate and annual effective dose are found to be much lower than the world average as well as from other countries of the world.

关键词： Accelerators beams and electromagnetism Nuclear physics Instrumentation and measurement Environmental and Earth science Particle physics and field theory Astrophysics and astroparticles

The response of the upper ocean to tropical cyclone Viyaru over the Bay of Bengal

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Acta Oceanologica Sinica 2019年第1期38卷 61-70页

作者： mir Kashem md Kawser Ahmed Fangli Qiao m A E akhter K m Azam Chowdhury Department of Oceanography University of Dhaka First Institute of Oceanography Ministry of Natural Resources Department of Physics Khulna University of Engineering & Technology

Better forecast of tropical cyclone(TC) can help to reduce risk and enhance management. The TC forecast depends on the scientific understanding of oceanic processes, air-sea interaction and finally, the atmospheric process. The TC Viyaru is taken as an example, which is formed at the end of 11 may 2013 and sustains up to 17 may 2013 during pre-monsoon season. Argo data are used to investigate ocean response processes by comparing pre-and post-conditions of the TC. Eight oceanic parameters including the sea surface temperature(SST), the sea surface salinity(SSS), and the barrier layer thickness(BLT), the 26°C isotherm depth in the ocean(D26), the isothermal layer depth(ILD), the mixed layer depth(mLD), the tropical cyclone heat potential(TCHP) and the effective oceanic layer for cyclogenesis(EOLC) are chosen to evaluate the pre-and post-conditions of the TC along the track of Viyaru. The values of the SST, D26, BLT, TCHP and EOLC in the pre-cyclonic condition are higher than the post-cyclonic condition, while the SSS, ILD and mLD in the post-cyclonic condition are higher than the pre-cyclonic condition of the ocean due to strong cyclonic winds and subsurface upwelling. It is interesting that the strong intensity of the TC reduces less SST and vice versa. The satisfied real time Argo data is not available in the northern Bay of Bengal especially in the coastal region. A weather research and forecasting model is employed to hindcast the track of Viyaru, and the satellite data from the National Center Environmental Prediction are used to assess the hindcast.

关键词： effective oceanic layer for cyclogenesis, sea surface temperature tropical cyclone tropical cyclone heat potential tropical cyclone viyaru weather research and forecasting model

Cylindrical and spherical Gardner solitons and double layers in a dusty electronegative non-thermal plasma with two-temperature electrons

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Chinese Physics B 2013年第7期22卷 339-345页

作者： T. akhter m. m. Hossain A. A. mamun Department of Physics Jahangirnagar University Department of Electrical and Electronic Engineering Bangladesh University of Business and Technology

A precise theoretical investigation has been made on the cylindrical and spherical （nonplanar） Gardner solitons （GSs） and double layers （DLs） in a dusty electronegative plasma （composed of inertial positive and negative ions, maxwellian cold electrons, non-thermal hot electrons, and negatively charged static dust）. The reductive perturbation method has been used in derivation of the modified Gardner （mG） equation describing the nonlinear propagation of the dust ion-acoustic （DIA） waves. The mG equation admits solitary waves （Sws） and DLs solutions for σ around its critical value σ c （where σc is the value of σ corresponding to the vanishing of the nonlinear coefficient of the Korteweg de-Vries （K-dV） equation）. The nonplanar Sws and DLs solutions are numerically analyzed and the parametric regimes for the existence of the positive as well as negative Sws and negative DLs are obtained. The basic features of nonplanar DIA Sws and DLs, which are found to be different from planar ones, are also identified. The implications of our results to different space and laboratory dusty plasma situations, are discussed.

关键词： electronegative plasma two-temperature electrons Garner solitons double layers

Synthesis and Characterization of Fe_(50)Cr_(14)mo_(14)C_(14)B_6Gd_2 Bulk Amorphous Steel

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Journal of materials Science & Technology 2010年第9期26卷 783-786页

作者： m. Iqbal J.I. akhter H.F. Zhang Z.Q. Hu Physics Division Pakistan Institute of Nuclear Science &: Technology P.O. Nilore Islamabad Pakistan Shenyang National Laboratory for materials Science Institute of Metal Research Chinese Academy of SciencesShenyang 110016 China

Bulk amorphous steel having 7 mm thickness was synthesized to evaluate its thermal stability and mechanical *** steel was synthesized by Cu mold casting technique using 1-2N pure *** of the material was done by X-ray diffraction,differential scanning calorimetry and scanning electron *** activation energies were calculated by Kissinger equation and it was found that the steel had better stability against *** properties like Vicker s hardness,nanohardness,elastic modulus and elastic recovery of as-cast and annealed samples were *** was concluded that the present steel had good glass-forming ability（GFA） and mechanical properties.

关键词： Bulk amorphous steels Activation energy Glass-forming ability mechanical properties

Antibacterial Characterization of Silver Nanoparticles against *** ATCC-15224

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Journal of materials Science & Technology 2008年第2期24卷 192-196页

作者： m.Raffi F.Hussain T.m.Bhatti J.I.akhter A.Hameed m.m.Hasan Department of Chemical and materials Engineering Pakistan Institute of Engineering and Applied Sciences(PIEAS)Islamabad-45650Pakistan Department of microbiology Faculty of Biological SciencesQuaid-i-Azam UniversityIslamabadPakistan Central Analytical Facility Division Pakistan Institute of Nuclear Science and Technology(PINSTECH)Islamabad-45650Pakistan Physics Division Pakistan Institute of Nuclear Science and Technology(PINSTECH)Islamabad-45650Pakistan

Silver nanoparticles of mean size 16 nm.w.re synthesized by inert gas condensation （IGC） method. Crystalline structure, morphology and nanoparticles size estimation were conducted by X-ray diffraction （XRD） and transmission electron microscopy （TEm）. Antibacterial activity of these silver nanoparticles as a function of particles concentration against gram-negative bacterium Escherichia coli （E. coli） was carried out in liquid as well as solid growth media. Scanning electron microscopy （SEm） and TEm studies showed that silver nanoparticles after interaction with *** have adhered to and penetrated into the bacterial cells. Antibacterial properties of silver nanoparticles are attributed to their total surface area, as a larger surface to volume ratio of nanoparticles provides more efficient means for enhanced antibacterial activity.

关键词： Silver Nanoparticles Antibacterial Electron microscopy

Effect of minor Alloying on Crystallization Behavior and Thermal Properties of Zr_(64.5)Ni_(15.5)Al_(11.5)Cu_(8.5) Bulk Amorphous Alloy

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Journal of materials Science & Technology 2011年第6期27卷 534-538页

作者： muhammad Iqbal Javed Iqbal akhter Haifeng Zhang Zhuangqi Hu microstructuralStudies Group Physics Division Pakistan Institute of Nuclear Science and Technology (PINSTECH) P.O. Nilore Islamabad Pakistan Shenyang Nationel Laboratory for materials Science Institute of Metal Research Chinese Academy of Sciences Shenyang 110016 China

minor alloying plays an important role in the synthesis and improvement of thermal stability of bulk metallic glasses（BmGs）.The present study was conducted to investigate the effect of minor additions of Y,Ti and Nb on the crystallization behavior and the thermal properties of Zr64.5Ni15.5Al11.5Cu8.5 *** parameters and the activation energies for crystallization were calculated for four（Zr0.645Ni0.155Al0.115-Cu0.085）100-xmx（m=Y,Ti and Nb,while x=0,2 at.） *** present alloys have wide supercooled liquid region of ≥87 *** activation energy was found to be greater than 300 kJ/mol for the base *** crystalline phases were identified in the samples annealed at 823 K for 20 *** glass transition temperature（Trg） and other thermal parameters such as γ,δ and β were improved by Y and Ti *** addition resists crystallization below annealing temperature 713 K,however,its effect on thermal properties is not very promising.

关键词： Activation energy Thermal properties Glass-forming ability Thermal stability Precipitation microstructure

Crystallization and Hardness of melt Spun Fe_(73)Si_(13)B_9Nb_4Cu_1 Alloy

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Journal of materials Science & Technology 2009年第1期25卷 48-52页

作者： J.I. akhter m. Iqbal m. Siddique m. Ahmad m.A. Haq m.A. Shaikh Z.Q. Hu Physics Division Pakistan Institute of Nuclear Science and Technology P. O. Nilore Islamabad Pakistan Shenyang National Laboratory for materials Science Institute of Metal Research Chinese Academy of Sciences Shenyang 110016 China Department of Chemical and materials Engineering Pakistan Institute of Engineering and Applied Sciences P.O. Nilore Islamabad Pakistan

An alloy having composition Fe73Si13B9Nb4Cu1 was synthesized by melt spinning to investigate the kinetics of crystallization. Techniques of differential scanning calorimetry （DSC）, X-ray diffraction （XRD） and mossbauer spectroscopy were employed to characterize the phases produced due to annealing at various temperatures. High temperature DSC revealed two stage crystallization reactions. First stage, crystallization occurs at temperature around 514℃ with the production of α-Fe （bcc） and Fe3Si phases. In the second stage, Fe2B and α-Fe （Si,Nb） phases were produced. mossbauer results revealed the formation of Fe3Si, Fe13Si3 and Fe7Si1 in the first stage and Fe3Si, Fe13Si3, Fe2B and α-Fe （Si,Nb） phases in the second stage of crystallization. An abrupt change in average internal magnetic field was observed at 500℃. The maximum hardness value was found for the sample heat-treated at 500℃.

关键词： Amorphous alloy Crystallization mossbauer spectroscopy Hardness

A monodisperse-aerosol generation system： Design, fabrication and performance

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Particuology 2017年第5期15卷 118-125页

作者： Amit md. Estiaque Arefin m.H. masud mohammad U.H. Joardder md. Shamim akhter Department of mechanical Engineering Rajshahi University of Engineering and Technology Rajshahi Bangladesh

monodisperse aerosols are essential in many applications, such as filter testing, aerosol instrument calibration, and experiments for validating models. This paper describes the design principle, construction, and performance of a monodisperse-aerosol generation system that comprises an atomizer, virtual impactor, microcontroller-based isokinetic probe, wind tunnel, and velocity measurement device. The size distribution of the produced monodisperse aerosols was determined by an optical particle counter. The effects of atomizer characteristics, the rates of minor and major flow, and solution criteria were investigated. It was found that all these parameters affect the generation of monodisperse aerosol. Finally, the expected geometric standard deviation （〈1.25） of monodisperse aerosol particles was obtained with the most suitable atomizer for 10% oleic acid in ethyl alcohol solution with 5%-15% minor flow, where the ratio between the nozzle-to-probe distance and acceleration-nozzle-exit diameter was 0.66. The con- structed monodisperse-aerosol-generation system can be used for instrumental calibration and aerosol research.

关键词： Aerosol generation monodisperse Design Sampling Counting

A Secured message Transmission Protocol for Vehicular Ad Hoc Networks

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Computers, materials & Continua 2021年第7期68卷 229-246页

作者： A.F.m.Suaib akhter A.F.m.Shahen Shah mohiuddin Ahmed Nour moustafa UnalÇavu¸soglu Ahmet Zengin Department of Computer Engineering Sakarya UniversitySakarya54050Turkey Department of Electrical and Electronics Engineering Istanbul Gelisim UniversityIstanbulTurkey School of Science Edith Cowan UniversityPerthWA6027Australia School of Engineering and Information Technology UNSWCanberra BC2610Australia

Vehicular Ad hoc Networks(VANETs)become a very crucial addition in the Intelligent Transportation System(ITS).It is challenging for a VANET system to provide security services and parallelly maintain high throughput by utilizing limited *** overcome these challenges,we propose a blockchain-based Secured Cluster-based mAC(SCB-mAC)*** nearby vehicles heading towards the same direction will form a cluster and each of the clusters has its blockchain to store and distribute the safety *** message which contains emergency information and requires Strict Delay Requirement(SDR)for transmission are called safety messages(Sm).Cluster members(Cms)sign Sms with their private keys while sending them to the blockchain to confirm authentication,integrity,and confidentiality of the message.A Certificate Authority(CA)is responsible for physical verification,key generation,and privacy preservation of the *** implemented a test scenario as proof of concept and tested the safety message transmission(SmT)protocol in a real-world *** and storage overhead analysis shows that the proposed protocol for SmT implements security,authentication,integrity,robustness,non-repudiation,*** maintaining the *** that are less important compared to the Sms are called non-safety messages(NSm)and vehicles use RTS/CTS mechanism for NSm *** studies show that the proposed NSm transmission method maintains 6 times more throughput,2 times less delay and 125%less Packet Dropping Rate(PDR)than traditional mAC *** results prove that the proposed protocol outperforms the traditional mAC protocols.

关键词： Ad hoc networks data security digital signatures distributed storage intelligent vehicles vehicular ad hoc networks wireless communication