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Frontiers in Energy 2022年第3期16卷 521-535页

作者： Gorakshnath Takalkar ahmad K.Sleiti Collage of Engineering Qatar UniversityDoha2713Qatar

The energy and exergy analyses of the absorption refrigeration system (ARS) using h2O-[mmim][DMP] mixture were investigated for a wide range of temperature. The equilibrium Dühring (P-T-XIL) and enthalpy (h-T-XIL) of mixture were assessed using the excess Gibbs free non-random two liquid (NRTL) model for a temperature range ??? of 20°C to 140°C and XIL from 0.1 to 0.9. The performance validation of the ARS cycle showed a better coefficient of performance (COP) of 0.834 for h2O-[mmim][DMP] in comparison to Nh3-h2O, h2O-LiBr, h2O-[emim][DMP], and h2O-[emim][BF4]. Further, ARS performances with various operating temperatures of the absorber (Ta), condenser (Tc), generator (Tg), and evaporator (Te) were simulated and optimized for a maximum COP and exergetic COP (ECOP). The effects of Tg from 50°C to 150°C and Ta and Tc from 30°C to 50°C on COP and ECOP, the Xa, Xg, and circulation ratio (CR) of the ARS were evaluated and optimized for Te from 5°C to 15°C. The optimization revealed that Tg needed to achieve a maximum COP which was more than that for a maximum ECOP. Therefore, this investigation provides criteria to select low grade heat source temperature. Most of the series flow of the cases of cooling water from the condenser to the absorber was found to be better than the absorber to the condenser.

关键词： ionic liquid driven absorption cycle h2O-[mmim][DMP] coefficient of performance(COP) exergy analysis thermodynamics mixture property

Optimal Machine Learning Enabled Intrusion Detection in Cyber-Physical System Environment

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Computers, Materials & Continua 2022年第9期72卷 4691-4707页

作者： Bassam A.Y.Alqaralleh Fahad Aldhaban Esam A.AlQarallehs ahmad h.Al-Omari MIS Department College of Business AdministrationUniversity of Business and TechnologyJeddah21448Saudi Arabia School of Engineering Princess Sumaya University for TechnologyAmman11941Jordan Faculty of Science Computer Science DepartmentNorthern Border UniversityArar91431Saudi Arabia

Cyber-attacks on cyber-physical systems(CPSs)resulted to sensing and actuation misbehavior,severe damage to physical object,and safety *** learning(ML)models have been presented to hinder cyberattacks on the CPS environment;however,the non-existence of labelled data from new attacks makes their detection quite *** Detection System(IDS)is a commonly utilized to detect and classify the existence of intrusions in the CPS environment,which acts as an important part in secure CPS *** developments in deep learning(DL)and explainable artificial intelligence(XAI)stimulate new IDSs to manage cyberattacks with minimum complexity and high *** this aspect,this paper presents an XAI based IDS using feature selection with Dirichlet Variational Autoencoder(XAIIDS-FSDVAE)model for *** proposed model encompasses the design of coyote optimization algorithm(COA)based feature selection(FS)model is derived to select an optimal subset of ***,an intelligent Dirichlet Variational Autoencoder(DVAE)technique is employed for the anomaly detection process in the CPS ***,the parameter optimization of the DVAE takes place using a manta ray foraging optimization(MRFO)model to tune the parameter of the *** order to determine the enhanced intrusion detection efficiency of the XAIIDS-FSDVAE technique,a wide range of simulations take place using the benchmark *** experimental results reported the better performance of the XAIIDSFSDVAE technique over the recent methods in terms of several evaluation parameters.

关键词： Cyber-physical systems explainable artificial intelligence deep learning security intrusion detection metaheuristics

Electronic Band Structure and Optical Parameters of Spinel SnMg_(2)O_(4) by Modified Becke–Johnson Potential

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Chinese Physics Letters 2012年第10期29卷 193-197页

作者： Masood Yousaf M.A.Saeed ahmad Radzi Mat Isa Amiruddin Shaari h.A.Rahnamaye Aliabad Physics Department Faculty of ScienceUniversiti Teknologi MalaysiaSkudai-81310JohorMalaysia Department of Physics Hakim Sabzevari UniversityIran

The electronic band structure and optical parameters of SnMg_(2)O_(4) are investigated by the first-principles technique based on a new potential approximation known as modified Becke–Johnson(mBJ).The direct band gap values by LDA,GGA and EV-GGA are underestimated significantly as compared to mBJ-GGA,which generally provides the results comparable to the experimental ***,the present band gap value(4.85 eV)using mBJ-GGA is greatly enhanced to the previous value by EV-GGA(2.823 eV).The optical parametric quantities(dielectric constant,index of refraction,reflectivity,optical conductivity and absorption coefficient)relying on the band structure are presented and *** first critical point(optical absorption's edge)in SnMg_(2)O_(4) occurs at about 4.85 eV.A strong absorption region is observed,extending between 5.4 eV to 25.0 *** SnMg_(2)O_(4),static dielectric constantε1(0),static refractive index n(0),and the magnitude of the coefficient of reflectivity at zero frequency R(0)are 2.296,1.515 and 0.0419,*** optoelectronic properties indicate that this material can be successfully used in optical devices.

关键词： absorption reflectivity dielectric

Numerical investigation for the suitable choice of bubble diameter correlation for EMMS/bubbling drag model

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Chinese Journal of Chemical Engineering 2022年第7期35卷 254-270页

作者： Nouman ahmad Jianqiang Deng Muhammad Adnan Shaanxi Key Laboratory of Energy Chemical Process Intensification Xi’an 710049China School of Chemical Engineering and Technology Xi’an Jiaotong UniversityXi’an 710049China

Mesoscale bubbles exist inherently in bubbling fluidized beds and hence should be considered in the constitutive modeling of the drag *** energy minimization multiscale bubbling(EMMS/bubbling)drag model takes the effects of mesoscale structures(i.e.,bubbles)into the modeling of drag coefficient and thus improves the coarse-grid simulation of bubbling and turbulent fluidized ***,its dependence on the bubble diameter correlation has not been thoroughly *** hydrodynamic disparity between homogeneous and heterogeneous fluidization is accounted for by the heterogeneity index,h_(d),which can be affected by choice of bubble diameter *** this choice of bubble diameter correlation influences the model prediction calls for further fundamental *** article incorporated seven different bubble diameter correlations into EMMS/bubbling drag model and studied their effects on h_(d).The performance of these correlations has been compared with the correlation used previously by EMMS/bubbling drag *** found that some of the correlations predicted lower hd by order of a magnitude than the correlation used by the original EMMS/bubbling *** on such analysis,we proposed a modification in the EMMS drag model for bubbling and turbulent fluidized beds.A computational fluid dynamics(CFD)simulation using two-fluid model with the modified EMMS/bubbling drag model was performed for two bubbling and one turbulent fluidized *** distribution,time averaged solid concentration and axial solid concentration profiles were studied and compared with the previous version of the EMMS/bubbling drag model and experimental *** found that the right choice of bubble diameter correlations can significantly improve the results for CFD simulations.

关键词： Mesoscale Bubbles Energy minimization multiscale(EMMS) heterogeneity index Bubbling fluidized bed

Numerical Study of Unsteady MhD Flow and Entropy Generation in a Rotating Permeable Channel with Slip and hall Effects

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Communications in Theoretical Physics 2018年第11期69卷 641-650页

作者： Z.h.Khan O.D.Makinde R.ahmad W.A.Khan State Key Laboratory of hydraulics and Mountain River Engineering College of Water Resource & HydropowerSichuan University Key Laboratory of Advanced Reactor Engineering and Safety Ministry of Education Tsinghua University Faculty of Military Science Stellenbosch University School of Mathematics and Physics University of Queensland Faculty of Engineering Sciences GIK Institute of Engineering Sciences and Technology Department of Mechanical Engineering College of Engineering Prince Mohammad Bin Fahd University

This article investigates an unbiased analysis for the unsteady two-dimensional laminar flow of an incompressible, electrically and thermally conducting fluid across the space separated by two infinite rotating permeable *** influence of entropy generation, hall and slip effects are considered within the flow analysis. The problem is modeled based on valid physical arguments and the unsteady system of dimensionless PDEs (partial differential equations) are solved with the help of Finite Difference Scheme. In the presence of pertinent parameters, the precise movement of the flow in terms of velocity, temperature, entropy generation rate, and Bejan numbers are presented graphically, which are parabolic in nature. Streamline profiles are also presented, which exemplify the accurate movement of the flow. The current study is one of the infrequent contributions to the existing literature as previous studies have not attempted to solve the system of high order non-linear PDEs for the unsteady flow with entropy generation and hall effects in a permeable rotating channel. It is expected that the current analysis would provide a platform for solving the system of nonlinear PDEs of the other unexplored models that are associated to the two-dimensional unsteady flow in a rotating channel.

关键词： unsteady flow rotating permeable channel MhD slip hall effects entropy analysis finite difference method

A New Class of L-Moments Based Calibration Variance Estimators

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Computers, Materials & Continua 2021年第3期66卷 3013-3028页

作者： Usman Shahzad Ishfaq ahmad Ibrahim Mufrah Almanjahie Nadia h.Al Noor Muhammad hanif Department of Mathematics and Statistics International Islamic UniversityIslamabad46000Pakistan Department of Mathematics and Statistics PMAS-Arid Agriculture UniversityRawalpindi46300Pakistan Department of Mathematics King Khalid UniversityAbha62529Saudi Arabia Statistical Research and Studies Support Unit King Khalid UniversityAbha62529Saudi Arabia Department of Mathematics College of ScienceMustansiriyah UniversityBaghdad10011Iraq

Variance is one of themost important measures of descriptive statistics and commonly used for statistical *** traditional second-order central moment based variance estimation is a widely utilized ***,traditional variance estimator is highly affected in the presence of extreme *** this paper initially,proposes two classes of calibration estimators based on an adaptation of the estimators recently proposed by Koyuncu and then presents a new class of L-Moments based calibration variance estimators utilizing L-Moments characteristics(L-location,Lscale,L-CV)and auxiliary *** is demonstrated that the proposed L-Moments based calibration variance estimators are more efficient than adapted *** data is considered for assessing the performance of the proposed *** also demonstrated an application related to apple fruit for purposes of the *** artificial and real data sets,percentage relative efficiency(PRE)of the proposed class of estimators with respect to adapted ones are *** PRE results indicate to the superiority of the proposed class over adapted ones in the presence of extreme *** this manner,the proposed class of estimators could be applied over an expansive range of survey sampling whenever auxiliary information is available in the presence of extreme values.

关键词： L-moments variance estimation calibration approach stratified random sampling

Effect of Niobium on Microstructure of Cast AISI h13 hot Work Tool Steel

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Journal of Iron and Steel Research International 2008年第4期15卷 61-66页

作者： Shahram Kheirandish ahmad Noorian Department of Material Science and Metallurgical Engineering Iran University of Science and TechnologyTehran 16846-13114 Iran

The effect of niobium addition on the microstructure of cast AISI h13 hot work tool steel was evaluated by using EDX analyzer attached to the scanning electron microscope. The volume percent of eutectic area and eutectic cell size and also volume percent of different carbides of new steel, which is heat treated under different conditions, are also determined. The results show that the a niobium addition modifies the cast structure of Nb-alloyed hot work tool steel, and reduces the size and volume of eutectic cells, and increases the maximum hardness of the steel.

关键词： hot work tool steel h13 niobium NbC microstructure

Influence of absorber doping in a-SiC:h/a-Si:h/a-SiGe:h solar cells

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Journal of Semiconductors 2012年第4期33卷 1-6页

作者： Muhammad Nawaz Ashfaq ahmad University Graduate Centre(UNIK) Gunnar Randers Vei 19P.O.Box 70N-2027 KjellerNorway COMSATs Institute of Information Technology Off-Raiwand RoadLahore-54000Pakistan

This work deals with the design evaluation and influence of absorber doping for aSi：h/aSiC：h/a SiGe：h based thinfilm solar cells using a twodimensional computer aided design （TCAD） tool. Various physical parameters of the layered structure, such as doping and thickness of the absorber layer, have been studied. For reliable device simulation with realistic predictability, the device performance is evaluated by implementing nec essary models （e.g., surface recombinations, thermionic field emission tunneling model for carrier transport at the heterojunction, SchokleyRead hall recombination model, Auger recombination model, bandgap narrowing ef fects, doping and temperature dependent mobility model and using FermiDirac statistics）. A single absorber with a graded design gives an efficiency of 10.1% for 800 nm thick multiband absorption. Similarly, a tandem design shows an efficiency of 10.4% with a total absorber of thickness of 800 nm at a bandgap of 1.75 eV and 1.0 eV for the top aSi and bottom aSiGe component cells. A moderate ndoping in the absorber helps to improve the efficiency while p doping in the absorber degrades efficiency due to a decrease in the Voc （and fill factor） of the device.

关键词： solar cells modeling TCAD amorphous silicon hIT cells

hacking Anti-Shoplifting System to hide Data within Clothes

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Computers, Materials & Continua 2021年第4期67卷 659-674页

作者： Al hussien Seddik Saad E.h.hafez Zubair ahmad Department of Computer Science Faculty of ScienceMinia UniversityAl-Minya61519Egypt Department of Mathematics Faculty of ScienceHelwan UniversityCairoEgypt Department of Statistics Yazd UniversityYazdIran

Steganography has been used to prevent unauthorized access to private information during *** is the scheme of securing sensitive information by concealing it within carriers such as digital images,videos,audio,or *** steganography methods are working by assigning a cover le then embed the payload within it by making some modications,creating the ***,the left traces that are caused by these modications will make steganalysis algorithms easily detect the hidden *** to solve this issue,a novel,highly robust steganography method based on hacking anti-shoplifting systems has proposed to hide data within *** anti-Shoplifting system is an anti-theft security system that protects goods and products,leaving the store in an illegal way(i.e.,without paying for them).The proposed method works by modifying the default anti-shoplifting system by changing its built-in soft RFID(radio-frequency identication)tags sewn in clothes into NFC(Near Field Communication)*** NFC tags are smart tags that can communicate with NFC-Enabled smart-phones using NDEF(NFC Data Exchange Format).NDEF is one of the advancements added to RFID technology by NFC,which allows the data *** NDEF message has one/more NDEF records that contain record type,a unique ID,a length,and a payload of data that contains the secret message content that can be any type of data that ts in a byte *** on NDEF and NFC-enabled smart-phones,the proposed method will take the secret message from the sender,make use of his NFC-enabled smart-phone to communicate with the NFC tag,then hide the secret message within the NDEF’s payload of the NFC tag stuck in ***,to evaluate the proposed method,it has been compared with default(digital)steganography weak *** as time,lockable,robustness,attacks,capacity,and a few more *** results and comparisons showed that the proposed method is more efcient than default(digital)steganography and

关键词： Near-eld communication radio-frequency identication Steganography data hiding tags

Dark energy in five-dimensional Brans-Dicke cosmology with dimensional reduction

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Research in Astronomy and Astrophysics 2011年第8期11卷 888-894页

作者： ahmad Rami El-Nabulsi Department of Nuclear Engineering Cheju National University South Korea College of Mathematics and Information Sciences Neijiang Normal University

We explore a 5D Brans-Dicke scalar cosmology by conjecturing that the four-dimensional hubble parameter varies as h = εФ^s, ε ∈ R and s is some unknown power index and that the extra-dimensions compactify as the visible dimensions expand as b（t） ≈ a^x （t）, x ∈R^-. We mainly discuss the case x = - 1. For critical values of e close to unity, it was observed that the acceleration of the universe occurs at red- shift close to z = 0.8 which indicates that in our model, accelerated expansion of the universe began only recently. Several interesting points are revealed and discussed in some detail.

关键词： Brans-Dicke cosmology -- dark energy