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Applied Mathematics(A Journal of Chinese Universities) 2024年第1期39卷 34-46页

作者： ZHOU Shuang-shuang Muhammad Ijaz khan sami ullah khan Sumaira Qayyum School of Science Hunan City UniversityYiyang 413000China Department of Mechanical Engineering Prince Mohammad Bin Fahd UniversityP.O.Box1664Al-Khobar 31952Kingdom of Saudi Arabia Department of Mathematics Namal UniversityMianwali 42250Pakistan Department of Mathematics Quaid-I-Azam University 45320Islamabad 44000Pakistan

The investigation endorsed the convective flow of Carreau nanofluid over a stretched surface in presence of entropy generation optimization.The novel dynamic of viscous dissipation is utilized to analyze the thermal mechanism of magnetized flow.The convective boundary assumptions are directed in order to examine the heat and mass transportation of nanofluid.The thermal concept of thermophoresis and Brownian movements has been re-called with the help of Buongiorno model.The problem formulated in dimensionless form is solved by NDSolve MATHEMATICA.The graphical analysis for parameters governed by the problem is performed with physical applications.The affiliation of entropy generation and Bejan number for different parameters is inspected in detail.The numerical data for illustrating skin friction,heat and mass transfer rate is also reported.The motion of the fluid is highest for the viscosity ratio parameter.The temperature of the fluid rises via thermal Biot number.Entropy generation rises for greater Brinkman number and diffusion parameter.

关键词： heat generation surface reaction CNTs based nano uid stretching/shrinking sheet thermal radiation

Adaptive Runtime Monitoring of Service Level Agreement Violations in Cloud Computing

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Computers, Materials & Continua 2022年第6期71卷 4199-4220页

作者： sami ullah khan Babar Nazir Muhammad Hanif Akhtar Ali Sardar Alam Usman Habib Department of Computer Science COMSATS UniversityAbbottabad CampusPakistan Faculty of Computer Science and Engineering Ghulam Ishaq Khan(GIK)Institute of Engineering Sciences and Technology TopiPakistan IFahja Pvt Limited PeshawarPakistan Department of Computer Science National University of Computer and Emerging Sciences IslamabadChiniot-Faisalabad CampusPakistan

The cloud service level agreement(SLA)manage the relationship between service providers and consumers in cloud computing.SLA is an integral and critical part of modern era IT vendors and communication contracts.Due to low cost and flexibility more and more consumers delegate their tasks to cloud providers,the SLA emerges as a key aspect between the consumers and providers.Continuous monitoring of Quality of Service(QoS)attributes is required to implement SLAs because of the complex nature of cloud communication.Many other factors,such as user reliability,satisfaction,and penalty on violations are also taken into account.Currently,there is no such policy of cloud SLA monitoring to minimize SLA violations.In this work,we have proposed a cloud SLA monitoring policy by dividing a monitoring session into two parts,for critical and non-critical parameters.The critical and non-critical parameters will be decided on the interest of the consumer during SLA negotiation.This will help to shape a new comprehensive SLA based Proactive Resource Allocation Approach(RPAA)which will monitor SLA at runtime,analyze the SLA parameters and try to find the possibility of SLA violations.We also have implemented an adaptive system for allocating cloud IT resources based on SLA violations and detection.We have defined two main components of SLA-PRAA i.e.,(a)Handler and(b)Accounting and Billing Manager.We have also described the function of both components through algorithms.The experimental results validate the performance of our proposed method in comparison with state-of-the-art cloud SLA policies.

关键词： Energy consumption penalty calculation proactive resource allocation service level agreement(SLA)monitoring SLA violation detection

Physical aspects of magnetized Jeffrey nanomaterial flow with irreversibility analysis

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Chinese Physics B 2022年第8期31卷 485-493页

作者： Fazal Haq Muhammad Ijaz khan sami ullah khan Khadijah M Abualnaja M A El-Shorbagy Department of Mathematics Karakoram International University Main CampusGilgit 15100Pakistan Department of Mathematics and Statistics Riphah International University I-14Islamabad 44000Pakistan Department of Mechanics and Engineering Science Peking UniversityBeijing 100871China Department of Mathematics COMSATS University IslamabadSahiwal 57000Pakistan Department of Mathematics and Statistics College of ScienceTaif UniversityP.O.Box 11099Taif 21944Saudi Arabia Department of Mathematics College of Science and Humanities in Al-KharjPrince Sattam bin Abdulaziz UniversityAl-Kharj 11942Saudi Arabia Department of Basic Engineering Science Faculty of EngineeringMenoufia UniversityShebin El-Kom 32511Egypt

This research presents the applications of entropy generation phenomenon in incompressible flow of Jeffrey nanofluid in the presence of distinct thermal features. The novel aspects of various features, such as Joule heating, porous medium,dissipation features, and radiative mechanism are addressed. In order to improve thermal transportation systems based on nanomaterials, convective boundary conditions are introduced. The thermal viscoelastic nanofluid model is expressed in terms of differential equations. The problem is presented via nonlinear differential equations for which analytical expressions are obtained by using the homotopy analysis method(HAM). The accuracy of solution is ensured. The effective outcomes of all physical parameters associated with the flow model are carefully examined and underlined through various curves. The observations summarized from current analysis reveal that the presence of a permeability parameter offers resistance to the flow. A monotonic decrement in local Nusselt number is noted with Hartmann number and Prandtl number.Moreover, entropy generation and Bejan number increases with radiation parameter and fluid parameter.

关键词： Jeffrey nonmaterial entropy generation magnetohydrodynamics(MHD) Bejan number porous medium Brownian motion

原位合成TiC颗粒增强6061基复合材料的制备及性能研究

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原位合成TiC颗粒增强6061基复合材料的制备及性能研究

作者： sami ullah khan 兰州理工大学

学位级别：硕士

与传统铝合金相比,铝基复合材料具有更好的机械性能,更高的比强度和比模量,因为这些优点,铝基复合材料可以被用于航空和汽车工业上。对于铝基复合材料而言,基体内增强相的数量、尺寸、分布等特性等对颗粒增强Al-6061复合材料的强度和韧... 详细信息

与传统铝合金相比,铝基复合材料具有更好的机械性能,更高的比强度和比模量,因为这些优点,铝基复合材料可以被用于航空和汽车工业上。对于铝基复合材料而言,基体内增强相的数量、尺寸、分布等特性等对颗粒增强Al-6061复合材料的强度和韧性有显著影响。目前,原位合成是用于制造Al6061-TiC增强金属基复合材料(AMC)的主要技术,但原位合成反应过程往往难以调控。因此,需要深入研究其反应机理和制备过程。本文采用X射线衍射仪(XRD),扫描电子显微镜(SEM)、透射电子显微镜(TEM)等表征方法研究了不同制备工艺条件下复合材料的微观结构和力学性能,包括维氏硬度、屈服强度、极限拉伸强度、晶粒细化和摩擦学性能。主要研究内容如下:1.本文使用6061铝合金作为基础合金,将TiO,C粉末采用原位合成的方法加入到6061铝合金中来制备铝基复合材料。实验结果表明,TiO和C的添加量从0wt%提高到7.5wt%,生成的增强颗粒(TiO+C)使铝基复合材料的弹性模量从63 GPa提高到72 GPa,硬度从0.94 GPa提高到1.14 GPa,当增强颗粒3.7 wt%则不会使得复合材料硬度继续增加。2.在1050℃和保温20min条件下,当TiO和C粉的添加量为7.5wt%,通过原位强化,铝基复合材料的综合力学性能较未经过颗粒增强的6061铝合金相比,其极限抗拉强度提高了约410%,铝基复合材料的极限屈服应力值为77 MPa。3.晶粒细化的研究是为了提高包括硬度、屈服强度和极限拉伸强度在内的力学性能,因为这些性能受到基体晶粒尺寸、增强颗粒尺寸、类型和增强颗粒分布的影响。通过添加增强剂,在添加量3.7wt%的铝基复合材料中,晶粒尺寸从280μm减小到到90μm,晶粒尺寸的细化提高了材料的强度和硬度。4.为了研究引入TiC后的复合材料的摩擦系数,使用针盘式摩擦计进行摩擦试验。研究结果表明,滑动可能是颗粒增强铝基复合材料COF(摩擦系数)降低的影响机制,与COF值为0.38的非增强铝基复合材料相比。随着COF的减小,表面平均粗糙度(Ra)由1.243μm逐渐降低到0.83μm,EDS分析显示Ra峰较低,颗粒增强铝基复合材料的表面比未增强6061铝合金表面光滑。5.通过扫描电镜分析,铝基复合材料表面的粗糙程度随着增强颗粒的加入而减小。对复合材料的耐磨性进行了比较,发现颗粒增强增强铝基复合材料的耐磨性优于未增强的复合材料,磨损率降低了3.8～1.9,这是由于TiC和AlO颗粒互相反应,在接触表面形成了更耐磨的摩擦层,使铝基复合材料的耐磨性增强。

关键词：原位制造技术金属基复合材料增强材料微观结构性能 Al-6061合金

Significance of activation energy and Wu's slip features in Cross nanofluid with motile microorganisms

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Communications in Theoretical Physics 2020年第10期72卷 1-11页

作者： sami ullah khan Hassan Waqas Taseer Muhammad Muhammad Imran Malik Zaka ullah Department of Mathematics COMSATS University IslamabadSahiwal 57000Pakistan Department of Mathematics Government College UniversityFaisalabad 38000Pakistan Department of Mathematics College of SciencesKing Khalid UniversityAbha 61413Saudi Arabia Department of Mathematics Faculty of ScienceKing Abdulaziz UniversityJeddah 21589Saudi Arabia

The current article investigates the impact of the bioconvection in an unsteady flow of magnetized Cross nanofluid with gyrotactic microorganisms and activation energy over a linearly stretched configuration.The analysis has been performed by utilizing the realistic Wu's slip boundary and zero mass flux conditions.The effects of nonlinear thermal radiation and the activation energy are also addressed.The governing flow equations are deduced to a dimensionless form by considering suitable transformations which are numerically targeted via a shooting algorithm.The physical visualization of each physical parameter governing the flow problem has been displayed graphically for distribution of velocity,temperature,concentration and motile microorganisms.The numerical treatment for the variation of skin friction coefficient,local Nusselt number,local Sherwood number and motile density number is performed in tabular forms.

关键词： Cross nanofluid nonlinear thermal radiation gyrotactic motile microorganism Wu's slip shooting technique

MHD flow study of viscous fluid through a complex wavy curved surface due to biomimetic propulsion under porosity and second-order slip effects

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Communications in Theoretical Physics 2021年第8期73卷 1-17页

作者： Pei-Ying Xiong Khurram Javid Mohsin Raza sami ullah khan M Ijaz khan Yu-Ming Chu College of Science Hunan City UniversityYiyang 413000China Department of Mathematics Northern UniversityWattar-Walai ZiaratKaka Saib Road24110NowsheraKPKPakistan Department of Mathematics COMSATS University IslamabadSahiwal 57000Pakistan Department of Mathematics and Statistics Riphah International University 1-14Islamabad 44000Pakistan Department of Mathematics Huzhou UniversityHuzhou 313000China

The steady laminar flow of viscous fluid from a curved porous domain under a radial magnetic field is considered.The fluid flow by a curved domain is due to peristaltic waves present at the boundary walls.The whole analysis is based on porosity(Darcy number)effects.Moreover,the effects of second-order slip on the rheology analysis are also discussed.Due to the complex nature of the flow regime,we have governed the rheological equations by using curvilinear coordinates in the fixed frame.The physical influence of magnetic(Hartmann number)and porosity(Darcy number)parameters on the rheological features of peristaltic transportation are argued in detailed(in the wave frame).Additionally,in the current study,the complex wavy pattern on both boundary walls of the channel is used.The whole rheological study is based on ancient,but medically valid,assumptions of creeping phenomena and long wavelength assumptions.Analytical solutions of the governing equations are obtained by using the simple integration technique in Mathematica software 11.0.The core motivation of the present analysis is to perceive the physical influence of embedded parameters,such as the dimensionless radius of the curvature parameter,magnetic parameter,porosity parameter,different amplitude ratios of complex peristaltic waves,first-and second-order slip parameters,on the axial velocity,pressure gradient,local wall shear stress,tangential component of the extra-stress tensor,pumping and trapping phenomena.

关键词： peristaltic waves magnetic field porous medium pumping phenomena second-order slip condition

Entropy generation applications in flow of viscoelastic nanofluid past a lubricated disk in presence of nonlinear thermal radiation and Joule heating

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Communications in Theoretical Physics 2021年第9期73卷 37-50页

作者： Aamar Abbasi Waseh Farooq M Ijaz khan sami ullah khan Yu-Ming Chu Zahid Hussain M Y Malik Department of Mathematics University of Azad Jammu and Kashmir Muzaffarabad13100 Pakistan Department of Mathematics and Statistics Riphah International University I-14Islamabad 44000Pakistan Department of Mathematics COMSATS University IslamabadSahiwal 57000Pakistan Department of Mathematics Huzhou UniversityHuzhou 313000China Department of Mathematics College of SciencesKing Khalid UniversityAbha 61413Saudi Arabia

Entropy generation is the loss of energy in thermodynamical systems due to resistive forces,diffusion processes,radiation effects and chemical reactions.The main aim of this research is to address entropy generation due to magnetic field,nonlinear thermal radiation,viscous dissipation,thermal diffusion and nonlinear chemical reaction in the transport of viscoelastic fluid in the vicinity of a stagnation point over a lubricated disk.The conservation laws of mass and momentum along with the first law of thermodynamics and Fick’s law are used to discuss the flow,heat and mass transfer,while the second law of thermodynamics is used to analyze the entropy and irreversibility.The numbers of independent variables in the modeled set of nonlinear partial differential equations are reduced using similarity variables and the resulting system is numerically approximated using the Keller box method.The effects of thermophoresis,Brownian motion and the magnetic parameter on temperature are presented for lubricated and rough disks.The local Nusselt and Sherwood numbers are documented for both linear and nonlinear thermal radiation and lubricated and rough disks.Graphical representations of the entropy generation number and Bejan number for various parameters are also shown for lubricated and rough disks.The concentration of nanoparticles at the lubricated surface reduces with the magnetic parameter and Brownian motion.The entropy generation declines for thermophoresis diffusion and Brownian motion when lubrication effects are dominant.It is concluded that both entropy generation and the magnitude of the Bejan number increase in the presence of slip.The current results present many applications in the lubrication phenomenon,heating processes,cooling of devices,thermal engineering,energy production,extrusion processes etc.

关键词： entropy generation viscoelastic fluid lubricated surface nonlinear thermal radiation Joule heating Keller box method

Slip flow of MHD Casson fluid in an inclined channel with variable transport properties

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Communications in Theoretical Physics 2020年第9期72卷 21-38页

作者： K V Prasad Hanumesh Vaidya C Rajashekhar sami ullah khan G Manjunatha J U Viharika Department of Mathematics Vijayanagara Sri Krishnadevaraya UniversityVinayaka NagarBallari-583105KarnatakaIndia Bhaskaracharya Study Chair Karnataka State Akkamahadevi Women's UniversityVijayapuraKarnatakaIndia Department of Mathematics COMSTAS University IslamabadSahiwal Campus 54000Pakistan Department of Mathematics Manipal Institute of TechnologyManipal Academy of Higher EducationManipalKarnataka576104-India

Due to the instructive role of the peristaltic phenomenon in the human body, interests have been developed in recent years towards peristaltic transport with various thermo-physical features.The current investigation reveals the effects of the magnetic field and variable transport properties on the peristaltic transport of a Casson fluid slip flow through an inclined channel.Nonlinear coupled partial differential equations regulate the fluid flow. Through the perturbation method, the momentum and energy equations are solved for small values of variable viscosity and thermal conductivity, and the closed-form solution is obtained for mass transfer. The impact on physiological quantities of related parameters of interest is evaluated and discussed via graphs. The results obtained for the current flow represent some interesting behaviors which have applications in the biomedical field.

关键词： velocity slip thermal slip concentration slip variable viscosity yield stress

Towards Blockchain-Based Secure BGP Routing,Challenges and Future Research Directions

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Computers, Materials & Continua 2024年第5期79卷 2035-2062页

作者： Qiong Yang Li Ma Shanshan Tu sami ullah MuhammadWaqas Hisham Alasmary Faculty of Information Technology Beijing University of TechnologyBeijing100124China School of Information Science and Technology North China University of TechnologyBeijing100144China Department of Computer Science Shaheed Benazir Bhutto UniversitySheringal18050Pakistan School of Computing and Mathematical Science Faculty of Engineering and ScienceUniversity of GreenwichLondonSE109LSUK School of Engineering Edith Cowan UniversityPerth6027Australia Department of Computer Science King Khalid UniversityAbha61421Saudi Arabia

Border Gateway Protocol(BGP)is a standard inter-domain routing protocol for the Internet that conveys network layer reachability information and establishes routes to different destinations.The BGP protocol exhibits security design defects,such as an unconditional trust mechanism and the default acceptance of BGP route announcements from peers by BGP neighboring nodes,easily triggering prefix hijacking,path forgery,route leakage,and other BGP security threats.Meanwhile,the traditional BGP security mechanism,relying on a public key infrastructure,faces issues like a single point of failure and a single point of trust.The decentralization,anti-tampering,and traceability advantages of blockchain offer new solution ideas for constructing secure and trusted inter-domain routing mechanisms.In this paper,we summarize the characteristics of BGP protocol in detail,sort out the BGP security threats and their causes.Additionally,we analyze the shortcomings of the traditional BGP security mechanism and comprehensively evaluate existing blockchain-based solutions to address the above problems and validate the reliability and effectiveness of blockchain-based BGP security methods in mitigating BGP security threats.Finally,we discuss the challenges posed by BGP security problems and outline prospects for future research.

关键词： BGP security blockchain prefix hijacking trust model secure routing

Enhancing Energy Efficiency with a Dynamic Trust Measurement Scheme in Power Distribution Network

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Computers, Materials & Continua 2024年第3期78卷 3909-3927页

作者： Yilei Wang Xin Sun Guiping Zheng Ahmar Rashid sami ullah Hisham Alasmary Muhammad Waqas Zhejiang Electric-Power Corporation Research Institute Zhejiang310014China Faculty of Information Technology Beijing University of TechnologyBeijing100124China Beijing Trusty Cloud Technology Co. Ltd.Beijing100022China Department of Computer Science and Engineering Ghulam Ishaq Khan Institute of Engineering Sciences and EngineeringTopi23640Pakistan Department of Computer Science Shaheed Benazir Bhutto UniversitySheringalUpper Dir18050Pakistan Department of Computer Science College of Computer ScienceKing Khalid UniversityAbha61421Saudi Arabia School of Computing and Mathematical Science Faculty of Engineering and ScienceUniversity of GreenwichLondonSE109LSUK School of Engineering Edith Cowan UniversityPerth6027Australia

The application of Intelligent Internet of Things(IIoT)in constructing distribution station areas strongly supports platform transformation,upgrade,and intelligent integration.The sensing layer of IIoT comprises the edge convergence layer and the end sensing layer,with the former using intelligent fusion terminals for real-time data collection and processing.However,the influx of multiple low-voltage in the smart grid raises higher demands for the performance,energy efficiency,and response speed of the substation fusion terminals.Simultaneously,it brings significant security risks to the entire distribution substation,posing a major challenge to the smart grid.In response to these challenges,a proposed dynamic and energy-efficient trust measurement scheme for smart grids aims to address these issues.The scheme begins by establishing a hierarchical trust measurement model,elucidating the trust relationships among smart IoT terminals.It then incorporates multidimensional measurement factors,encompassing static environmental factors,dynamic behaviors,and energy states.This comprehensive approach reduces the impact of subjective factors on trust measurements.Additionally,the scheme incorporates a detection process designed for identifying malicious low-voltage end sensing units,ensuring the prompt identification and elimination of any malicious terminals.This,in turn,enhances the security and reliability of the smart grid environment.The effectiveness of the proposed scheme in pinpointing malicious nodes has been demonstrated through simulation experiments.Notably,the scheme outperforms established trust metric models in terms of energy efficiency,showcasing its significant contribution to the field.

关键词： IIoT trusted measure energy efficient