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Joint optimization for secure ambient backscatter communication in NOMA-enabled IoT networks

Digital Communications and Networks 2023年第1期9卷 264-269页

作者： wali ullah khan Furqan Jameel Asim Ihsan Omer Waqar Manzoor Ahmed Interdisciplinary Centre for Security Reliability and Trust(SnT)/SigComUniversity of LuxembourgLuxembourg Department of Communications and Networking Aalto University02150EspooFinland Department of Communication and Information Engineering Shanghai Jiao Tong UniversityShanghai200240China Department of Engineering Thompson Rivers University(TRU)British Columbia(BC)Canada College of Computer Science and Technology Qingdao UniversityQingdao266071China

Non-Orthogonal Multiple Access(NOMA)has emerged as a novel air interface technology for massive connectivity in Sixth-Generation(6G)*** recent integration of NOMA in Backscatter Communication(BC)has triggered significant research interest due to its applications in low-powered Internet of Things(IoT)***,the link security aspect of these networks has not been well *** article provides a new optimization framework for improving the physical layer security of the NOMA ambient BC *** system model takes into account the simultaneous operation of NOMA IoT users and the Backscatter Node(BN)in the presence of multiple EavesDroppers(EDs).The EDs in the surrounding area can overhear the communication of Base Station(BS)and BN due to the wireless broadcast ***,the chief aim is to enhance link security by optimizing the BN reflection coefficient and BS transmit *** gauge the performance of the proposed scheme,we also present the suboptimal NOMA and conventional orthogonal multiple access as benchmark *** Carlo simulation results demonstrate the superiority of the NOMA BC scheme over the pure NOMA scheme without the BC and conventional orthogonal multiple access schemes in terms of system secrecy rate.

关键词： 6G Non-orthogonal multiple access Ambient backscatter communication Internet-of-things Joint optimization Physical layer security

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Ambient BackCom in beyond 5G NOMA networks: A multi-cell resource allocation framework

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Digital Communications and Networks 2022年第6期8卷 1005-1013页

作者： wali ullah khan Fida Hussain Memon Kapal Dev Muhammad Awais Javed Dinh-Thuan Do Nawab Muhammad Faseeh Qureshi Interdisciplinary Centre for Security Reliability and Trust(SnT)University of Luxembourg1855 Luxembourg CityLuxembourg Department of Electrical Engineering Sukkur IBA University Pakistan Department of Institute of Intelligent Systems University of JohannesburgSouth Africa Department of Electrical and Computer Engineering COMSATS University Islamabad44000IslamabadPakistan Electrical Engineering Department University of Colorado DenverDenverCO80204USA Department of Computer Education Sungkyunkwan UniversitySeoulSouth Korea

The research of Non-Orthogonal Multiple Access (NOMA) is extensively used to improve the capacity of networks beyond the fifth-generation. The recent merger of NOMA with ambient Backscatter Communication (BackCom), though opening new possibilities for massive connectivity, poses several challenges in dense wireless networks. One such challenge is the performance degradation of ambient BackCom in multi-cell NOMA networks under the effect of inter-cell interference. Driven by providing an efficient solution to the issue, this article proposes a new resource allocation framework that uses a duality theory approach. Specifically, the sum rate of the multi-cell network with backscatter tags and NOMA user equipment is maximized by formulating a joint optimization problem. To find the efficient base station transmit power and backscatter reflection coefficient in each cell, the original problem is first divided into two subproblems, and then the closed form solution is derived. A comparison with the Orthogonal Multiple Access (OMA) ambient BackCom and pure NOMA transmission has been provided. Simulation results of the proposed NOMA ambient BackCom indicate a significant improvement over the OMA ambient BackCom and pure NOMA in terms of sum-rate gains.

关键词： Beyond fifth-generation Non-orthogonal multiple access Ambient BackCom Spectrum efficiency optimization

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Testing Procedure for Laboratory Scale Semi Cryogenic Combustion Chamber of LPRE with Problems Faced and Lessons Learned

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Journal of Thermal Science 2022年第6期31卷 2171-2177页

作者： khan Taj wali QAMAR Ihtzaz Department of Aeronautics and Astronautics Institute of Space TechnologyIslamabad 44000Pakistan

Design, development, and testing of LPRE(Liquid Propellant Rocket Engine) are difficult and expensive tasks. Prior to full-scale design, it is indispensable to optimize important parameters at sub-scale. Propellants flow rates are low for a sub-scale or laboratory scale combustion chambers. It is hard to satisfy chamber cooling and chill feed lines quickly with low flow rates of propellants. This paper proposes a detailed procedure for testing of a laboratory scale semi-cryogenic combustion chamber. Many tests were conducted with a small scale adjustable length combustion chamber. The injection head of the chamber was interchangeable. Liquid-liquid pressure swirl injector and like impinging injectors were used with two different injection heads. Liquid oxygen and kerosene were used as oxidizer and fuel, respectively. Oxidizer to fuel mixing ratio was 0.29-0.45 and the total propellant mass flow rate was 0.06-0.1 kg/s. Problems were faced during testing, including, explosion in the combustion chamber, fuel injector blockage, unstable combustion, incomplete chilling and blockage of cooling water channel, etc. A detailed procedure is designed on the basis of the lessons learned which was experimentally proved.

关键词： LPRE cryogenic testing procedure combustion chamber

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Feasibility-Guided Constraint-Handling Techniques for Engineering Optimization Problems

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Computers, Materials & Continua 2021年第6期67卷 2845-2862页

作者： Muhammad Asif Jan Yasir Mahmood Hidayat ullah khan wali khan Mashwani Muhammad Irfan Uddin Marwan Mahmoud Rashida Adeeb khanum Ikramullah Noor Mast Institute of Numerical Sciences Kohat University of Science&TechnologyKohatPakistan Department of Economics Abbottabad University of Science&TechnologyAbbottabadPakistan Institute of Computing Kohat University of Science&TechnologyKohatPakistan Faculty of Applied Studies King Abdulaziz UniversityJeddahSaudi Arabia Jinnah College for Women University of PeshawarPeshawarPakistan Department of Physics Kohat University of Science&TechnologyKohatPakistan

The particle swarm optimization(PSO)algorithm is an established nature-inspired population-based meta-heuristic that replicates the synchronizing movements of birds and *** is essentially an unconstrained algorithm and requires constraint handling techniques(CHTs)to solve constrained optimization problems(COPs).For this purpose,we integrate two CHTs,the superiority of feasibility(SF)and the violation constraint-handling(VCH),with a *** CHTs distinguish feasible solutions from infeasible ***,in SF,the selection of infeasible solutions is based on their degree of constraint violations,whereas in VCH,the number of constraint violations by an infeasible solution is of more ***,a PSO is adapted for constrained optimization,yielding two constrained variants,denoted SF-PSO and *** SF-PSO and VCH-PSO are evaluated with respect to ve engineering problems:the Himmelblau’s nonlinear optimization,the welded beam design,the spring design,the pressure vessel design,and the three-bar truss *** simulation results show that both algorithms are consistent in terms of their solutions to these problems,including their different available *** of the SF-PSO and the VCHPSO with other existing algorithms on the tested problems shows that the proposed algorithms have lower computational cost in terms of the number of function evaluations *** also report our disagreement with some unjust comparisons made by other researchers regarding the tested problems and their different variants.

关键词： Constrained evolutionary optimization constraint handling techniques superiority of feasibility violation constraint-handling technique swarm based evolutionary algorithms particle swarm optimization engineering optimization proble

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Response of basement wall in tall buildings foundation under lateral loading

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Frontiers of Structural and Civil Engineering 2022年第11期16卷 1415-1423页

作者： Irfan JAMIL Irshad AHMAD Aqeel Ur REHMAN Aqib AHMED Ameer HAMZA wali ullah Department of Civil Engineering University of Engineering and TechnologyPeshawar 25000Pakistan

With increasing population and limitation of availability of land,tall buildings supported on piled raft foundations are increasingly used in the modern *** increase the ratio of floor area to height,and to fulfill storage and parking facilities requirements,these tall buildings usually have more than one basement ***,during the foundation design,engineers have not considered the basement wall contribution to resisting lateral load induced by earthquake or wind and this can result in an uneconomical construction of *** this research work,an experimental study was performed on small-scale models,in order to study basement wall contribution,and the raft contribution including for piled raft foundations,to resisting lateral *** configurations of piles in 2×2,2×3,and 3×3 patterns were tested as a pile group,piled raft and piled raft with a basement *** show that when a basement wall is present,the lateral displacement decreases and the demand on each pile *** piled raft design can become more economical for tall buildings if the basement’s walls are taken into account.

关键词： basement wall lateral load displacement piled raft

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Monte-Carlo simulation of a stochastic differential equation

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Plasma Science and Technology 2017年第12期19卷 6-14页

作者： Arif ullah Majid khan M KAMRAN R khan 盛正卯 Hefei National Laboratory for Physical Sciences at the Microscale University of Science and Technology of ChinaHefei 230026People's Republic of China Department of Physics Quaid-i-Azam University Islamabad Pakistan Department of Physics Institute of Fusion Theory and SimulationsZhejiang UniversityHangzhou 310027People's Republic of China Department of Physics COMSATS Institute of Information TechnologyChack ShahzadIslamabadPakistan Department of Physics Abdul Wali Khan University23200 MardanKPKPakistan

For solving higher dimensional diffusion equations with an inhomogeneous diffusion coefficient,Monte Carlo（MC） techniques are considered to be more effective than other algorithms, such as finite element method or finite difference method. The inhomogeneity of diffusion coefficient strongly limits the use of different numerical techniques. For better convergence, methods with higher orders have been kept forward to allow MC codes with large step size. The main focus of this work is to look for operators that can produce converging results for large step sizes. As a first step, our comparative analysis has been applied to a general stochastic ***, our formulization is applied to the problem of pitch angle scattering resulting from Coulomb collisions of charge particles in the toroidal devices.

关键词： Monte-Carlo simulation stochastic differential equations toroidal plasmas numerical methods

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Influences of Marangoni convection and variable magnetic field on hybrid nanofluid thin-film flow past a stretching surface

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Chinese Physics B 2022年第6期31卷 494-501页

作者： Noor wali khan Arshad khan Muhammad Usman Taza Gul Abir Mouldi Ameni Brahmia Department of Mathematics City University of Science and ITPeshawar 25000Pakistan College of Aeronautical Engineering National University of Sciences and Technology(NUST)Sector H-12Islamabad 44000Pakistan Higher Education Archives and Libraries Department KP Govt.Superior Science CollegePeshawarPakistan Department of Industrial Engineering College of EngineeringKing Khalid UniversityAbha 61421KSA Chemistry Department College of ScienceKing Khalid UniversityAbha 61413Saudi Arabia

Investigations on thin-film flow play a vital role in the field of optoelectronics and magnetic *** films are reasonably hard and thermally stable but quite *** thermal stability of a thin film can be further improved by incorporating the effects of *** the current work,a stretchable surface is considered upon which hybrid nanofluid thin-film flow is taken into *** idea of augmenting heat transmission by making use of a hybrid nanofluid is a focus of the current *** flow is affected by variations in the viscous forces,along with viscous dissipation effects and Marangoni convection.A time-constrained magnetic field is applied in the normal direction to the flow *** equations governing the flow system are shifted to a non-dimensional form by applying similarity *** homotopy analysis method is employed to find the solution to the resultant *** is noticed in this study that the flow characteristics decline with augmentation of magnetic,viscosity and unsteadiness parameters while they increase with enhanced values of thin-film *** characteristics are supported by increasing values of the Eckert number and the unsteadiness parameter and opposed by the viscosity parameter and Prandtl *** numerical impact of different emerging parameters upon skin friction and the Nusselt number is calculated in tabular form.A comparison of current work with established results is carried out,with good agreement.

关键词： thin-film flow hybrid nanofluid viscous dissipation stretching surface homotopy analysis method

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Dynamical system of a SEIQV epidemic model with nonlinear generalized incidence rate arising in biology

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International Journal of Biomathematics 2017年第7期10卷 107-125页

作者： Muhammad Altaf khan Yasir khan Taj wali khan Saeed Islam Department of Mathematics Abdul wali khan University Mardan Khyber Pakhtunkhwa Pakistan Department of Mathematics University of Haft Al-Batin Haft Al-Batin 31991 Saudi Arabia

In this paper, a dynamical system of a SEIQV mathematical model with nonlinear generalized incidence arising in biology is investigated. The stability of the disease-free and endemic equilibrium is discussed. The basic reproduction number of the model is obtained. We found that the disease-free and endemic equilibrium is stable locally as well as globally asymptotically stable. For R0〈1, the disease-free equilibrium is stable both locally and globally and for R0〉1, the endemic equilibrium is stable globally asymptotically. Finally, some numerical results are presented.

关键词： Epidemic model SEIQV model vaccination global stability numerical solution.

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Variation in patient dose due to differences in calibration and dosimetry protocols

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Nuclear Science and Techniques 2018年第5期29卷 44-49页

作者： Wazir Muhammad Asad ullah Gulzar khan Tahir Zeb khan Tauseef Jamaal Fawad ullah Matiullah khan Amjad Hussain Department of Therapeutic Radiology Yale-School of MedicineYale UniversityNew HavenCT 06520-8040USA Heath Physics Division(HPD) Pakistan Institute of Nuclear Science and Technology(PINSTECH)Islamabad 45650Pakistan Department of Physics Abul Wali Khan UniversityMardan 23200Pakistan Pakistan Institute Nuclear Science&Technology(PIEAS) Islamabad 45650Pakistan Department of Physics Kohat University of Science and TechnologyKohat 26000Pakistan Department of Medical Physics CancerCare ManitobaBrandonMB R7A 2B3Canada

For precise and accurate patient dose delivery,the dosimetry system must be calibrated properly according to the recommendations of standard dosimetry protocols such as TG-51 and TRS-398. However, the dosimetry protocol followed by a calibration laboratory is usually different from the protocols that are followed by different clinics, which may result in variations in the patient *** prime objective in this study was to investigate the effect of the two protocols on dosimetry *** measurements were performed for a Co-60 teletherapy unit and a high-energy Varian linear accelerator with 6 and 15 MV photon and 6, 9, 12, and 15 MeV electron beams, following the recommendations and procedures of the AAPM TG-51 and IAEA TRS-398 dosimetry protocols. The dosimetry systems used for this study were calibrated in a Co-60 radiation beam at the Secondary Standard Dosimetry Laboratory(SSDL) PINSTECH,Pakistan, following the IAEA TRS-398 protocol. The ratio of the measured absorbed doses to water in clinical setting,D_w(TG-51/TRS-398), was 0.999 and 0.997 for 6 and15 MV photon beams,whereas these ratios were 1.013,1.009, 1.003, and 1.000 for 6, 9, 12, and 15 MeV electron beams, respectively. This difference in the absorbed dosesto-water D_w ratio may be attributed mainly due to beam quality(K_Q) and ion recombination correction factor.

关键词： Radiation dosimetry Dosimetry systems calibrations Patient dose Absorbed dose-to-water ratio AAPM TG-51 IAEA TRS-398

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Absolute partial and total ionization cross sections of carbon monoxide with electron collision from 350 eV to 8000 eV

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Chinese Physics B 2024年第4期33卷 459-464页

作者： Taj wali khan 黄伟哲王恩亮单旭陈向军 Hefei National Research Center of Physical Sciences at the Microscale and Department of Modern Physics University of Science and Technology of ChinaHefei 230026China

The absolute partial and total cross sections for electron impact ionization of carbon monoxide are reported for electron energies from 350 eV to 8000 *** product ions(CO^(+),C^(+),O^(+),CO^(2+),C^(2+),and O^(2+))are measured by employing an ion imaging mass spectrometer and two ion-pair dissociation channels(C^(+)+O^(+)and C^(2+)+O^(+))are *** absolute cross sections for producing individual ions and their total,as well as for the ion-pair dissociation channels are obtained by normalizing the data of CO^(+)to that of Ar^(+)from CO-Ar mixture target with a fixed 1:1 *** overall errors are evaluated by considering various kinds of uncertainties.A comprehensive comparison is made with the available data,which shows a good agreement with each other over the energy ranges that are *** work presents new cross-section data with electron energies above 1000 eV.

关键词： electron impact ionization cross sections carbon monoxide ion imaging mass spectrometer

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