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Metamaterial terahertz device with temperature regulation function that can achieve perfect absorption and complete reflection conversion of ultrawideband

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Communications in Theoretical Physics 2024年第7期76卷 123-133页

作者： Hao Sun Zao Yi Can Ma Shubo Cheng bin Tang Qingdong Zeng Sohail ahmad School of Mathematics and Science Joint Laboratory for Extreme Conditions Matter PropertiesState Key Laboratory of Environment-Friendly Energy MaterialsTianfu Institute of Research and InnovationSouthwest University of Science and TechnologyMianyang 621010China Department of Oncology Sichuan Science City HospitalMianyangSichuan Province621000China School of Chemistry and Chemical Engineering Jishou UniversityJishou 416000China School of Physics and Optoelectronic Engineering Yangtze UniversityJingzhouHubei 434023China School of Microelectronics and Control Engineering Changzhou UniversityChangzhou 213164China School of Physics and Electronic Information Engineering Hubei Engineering UniversityXiaogan 432000China Institute of Physics Bahauddin Zakariya UniversityMultan 66000Pakistan

The field of terahertz devices is important in terahertz ***,most of the current devices have limited functionality and poor *** improve device performance and achieve multifunctionality,we designed a terahertz device based on a combination of VO_(2)and *** device can be tuned using the phase-transition characteristics of VO_(2),which is included in the triple-layer structure of the device,along with SiO_(2)and *** terahertz device exhibits various advantageous features,including broadband coverage,high absorption capability,dynamic tunability,simple structural design,polarization insensitivity,and incidentangle *** simulation results showed that by controlling the temperature,the terahertz device achieved a thermal modulation range of spectral absorption from 0 to *** 313 K,the device exhibited complete reflection of terahertz *** the temperature increased,the absorption rate also *** the temperature reached 353 K,the device absorption rate exceeded 97.7%in the range of 5-8.55 *** study used the effective medium theory to elucidate the correlation between conductivity and temperature during the phase transition of VO_(2).Simultaneously,the variation in device performance was further elucidated by analyzing and depicting the intensity distribution of the electric field on the device surface at different ***,the impact of various structural parameters on device performance was examined,offering valuable insights and suggestions for selecting suitable parameter values in real-world *** characteristics render the device highly promising for applications in stealth technology,energy harvesting,modulation,and other related fields,thus showcasing its significant potential.

关键词： terahertz perfect absorption complete reflection temperature regulation ultrawideband smart device

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Antioxidant and antimicrobial properties of Litsea elliptica Blume and Litsea resinosa Blume(Lauraceae)

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Asian Pacific Journal of Tropical Biomedicine 2014年第5期4卷 386-392页

作者： Mui-Hung Wong Li-Fang Lim Fasihuddin bin ahmad Zaini bin Assim Faculty of Applied Sciences Universiti.Teknologi MARA.Samarahan CampusSarawak Branch Faculty of Engineering Computing and Science.Swinburne University of TechnologySarawak Campus Department of Chemistry Faculty of Resource Science and TechnologyUniversiti Malaysia Sarawak

Objective:To investigate antioxidant and antimicrobial activities of two plant species,Litsea elliptica(L elliptica) and Litsea resinosa(L resinosa).Methods:In vitro method-2,2-diphenyl-1-picrylhydrazyl radical scavenging assay was conducted for antioxidant activity detennination while antimicrobial assay consisted of agar well diffusion assay and mycelial radial growth ***:Methanol extracts of root and stem of L elliptica and L resinosa exhibited the highest antioxidant activity with EC_(50)of 23.99,41.69,11.22 and 33.48 mg/*** methanol extracts of L resinosa as well as root extracts from L elliptica showed significant scavenging *** extract from stem of L resinosa presented the largest inhibition zone in Gramnegative bacteria Pseudomonas aeruginosa and Escherichia coli while chloroform extract from inner bark of L resinosa showed major inhibition towards Gram-positive bacteria Bacillus *** oils from the root of both species showed significant antifungal activities which are 80.11%and 66.85%***:Overall,methanol extracts from root and stem of both species showed antioxidant activity comparable to standard butylated *** from L resinosa demonstrated stronger antimicrobial properties compared to that from L elliptica.

关键词： Litsea elliptica Litsea resinosa Antioxidant Antifungal Antibacterial EC_(50)

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High Gain of UWB Planar Antenna Utilising FSS Reflector for UWB Applications

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Computers, Materials & Continua 2022年第1期70卷 1419-1436页

作者： Ahmed Jamal Abdullah Al-Gburi Imran bin Mohd Ibrahim Zahriladha Zakaria Badrul Hisham ahmad Noor Azwan bin Shairi Mohammed Yousif Zeain Department of Electronics and Computer Engineering(FKEKK) Center for Telecommunication Research and Innovation(CeTRI)Universiti Teknikal Malaysia Melaka(UTeM)Durian TunggalMalaccaMalaysia

In this paper,a high gain and directional coplanarwaveguide(CPW)-fed ultra-wideband(UWB)planar antenna with a new frequency selective surface(FSS)unit cells design is proposed for UWB *** proposed UWB antenna was designed based on the Mercedes artistic-shaped planar(MAP)*** antenna consisted of a circular ring embedded with three straight legs for antenna impedance bandwidth *** modelled FSS used the integration of a two parallel conductive metallic patch with a circular loop *** FSS provided a UWB stopband filter response covering a bandwidth of 10.5 GHz,for frequencies from 2.2 to 12.7 *** proposed FSS had a compact physical dimension of 5 mm×5 mm×1.6 mm,with a printed array of 19×19 FSS unit *** FSS unit cells were printed on only one side of the dielectric FR4 substrate and placed as a sandwich between the antenna and the reflector ground *** equivalent circuit configuration(ECC)was used to verify the FSS unit cell structure’s *** simulated results indicated that the UWB MAP antenna and FSS reflector provided a fractional bandwidth of 136%and a high gain of 11.5 dB at 8.5 GHz with an acceptable radiation efficiency of 89%.Furthermore,the gain was improved across the operating band and kept between 8.3 and 11.5 *** proposed antenna was in good agreement between theoretical and experimental results and offered a wide enough bandwidth for UWB and vehicle applications.

关键词： UWB MAP antenna stable gain FSS reflector ECC stopband response reflection phase

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Offshore Software Maintenance Outsourcing Process Model Validation:A Case Study Approach

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Computers, Materials & Continua 2023年第3期74卷 5035-5048页

作者： Atif Ikram Masita Abdul Jalil Amir bin Ngah Adel Sulaiman Muhammad Akram ahmad Salman Khan Faculty of Ocean Engineering Technology and Informatics University Malaysia TerengganuKuala TerengganuMalaysia Department of Computer Science&Information Technology Faculty of Information TechnologyThe University of LahoreLahore54000Pakistan Department of Computer Science College of Computer Science and Information SystemsNajran UniversityNajranSaudi Arabia Department of Software Engineering Faculty of Information TechnologyThe University of LahoreLahore54000Pakistan

The successful execution and management of Offshore Software Maintenance Outsourcing(OSMO)can be very beneficial for OSMO vendors and the OSMO *** a lot of research on software outsourcing is going on,most of the existing literature on offshore outsourcing deals with the outsourcing of software development *** frameworks have been developed focusing on guiding software systemmanagers concerning offshore software ***,none of these studies delivered comprehensive guidelines for managing the whole process of *** is a considerable lack of research working on managing OSMO from a vendor’s ***,to find the best practices for managing an OSMO process,it is necessary to further investigate such complex and multifaceted phenomena from the vendor’s *** study validated the preliminary OSMO process model via a case study research *** results showed that the OSMO process model is applicable in an industrial setting with few *** industrial data collected during the case study enabled this paper to extend the preliminary OSMO process *** refined version of the OSMO processmodel has four major phases including(i)Project Assessment,(ii)SLA(iii)Execution,and(iv)Risk.

关键词： Offshore outsourcing process model model validation vendor challenges case study

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Concealing arbitrary objects remotely with multi-folded transformation optics

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Light(Science & Applications) 2016年第1期5卷 378-386页

作者： bin Zheng Hamza ahmad Madni Ran Hao Xianmin Zhang Xu Liu Erping Li Hongsheng Chen State Key Laboratory for Modern Optical Instrumentation Zhejiang UniversityHangzhou 310027China The Innovative Institute of Electromagnetic Information and Electronic Integration Zhejiang UniversityHangzhou 310027China The Electromagnetics Academy at Zhejiang University Zhejiang UniversityHangzhou 310027China

An invisibility cloak that can hide an arbitrary object external to the cloak itself has not been devised *** this Letter,we introduce a novel way to design a remote cloaking device that makes any object located at a certain distance *** is accomplished using multi-folded transformation optics to remotely generate a hidden region around the object that no field can penetrate and that does not disturb the far-field scattering electromagnetic *** a result,any object in the hidden region can stay in position or move freely within that region and remain *** idea is further extended in order to design a remote illusion optics that can transform any arbitrary object into another *** other cloaking methods,this method would require no knowledge of the details of the object *** proposed multi-folded transformation optics will be crucial in the design of remote devices in a variety of contexts.

关键词： multi-folded object independent remote cloaking transformation optics

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Forestvoltaics,Floatovoltaics and Building Applied Photovoltaics(BAPV)Potential for a University Campus

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Energy Engineering 2024年第9期121卷 2331-2361页

作者： Rittick Maity Muhammad Khairul Imran bin ahmad Shuhaimi Kumarasamy Sudhakar Amir Abdul Razak Faculty of Electrical and Electronics Engineering Technology Universiti Malaysia Pahang Al-Sultan AbdullahPekan26600Malaysia Centre for Research in Advanced Fluid and Processes UniversitiMalaysia Pahang Al-Sultan AbdullahGambang26300Malaysia Faculty of Mechanical and Automotive Engineering Technology Universiti Malaysia Pahang Al-Sultan AbdullahPekan26600Malaysia Centre for Automotive Engineering Universiti Malaysia Pahang Al-Sultan AbdullahPekan26600Malaysia Energy Centre Maulana Azad National Institute of TechnologyBhopal462003India

The United Nations’Sustainable Development Goals(SDGs)highlight the importance of affordable and clean energy *** energy is a perfect example,being both renewable and *** popularity shows no signs of slowing down,with solar photovoltaic(PV)panels being the primary technology for converting sunlight into *** are continuously being made to ensure cost-effectiveness,high-performing cells,extended lifespans,and minimal maintenance *** study focuses on identifying suitable locations for implementing solar PVsystems at theUniversityMalaysia PahangAl SultanAbdullah(UMPSA),Pekan campus including buildings,water bodies,and forest areas.A combined technical and economic analysis is conducted using Helioscope for simulations and the Photovoltaic Geographic Information System(PVGIS)for economic *** simulation examine case studies for PV installations in forested areas,lakes,and *** approach provides comprehensive estimations of solar photovoltaic potential,annual cost savings,electricity costs,and greenhouse gas emission *** on land coverage percentages,Floatovoltaics have a large solar PV capacity of 32.3 Megawatts(MW);forest-based photovoltaics(Forestvoltaics)achieve maximum yearly savings of RM 37,268,550;and Building Applied Photovoltaics(BAPV)have the lowest CO2 emissions and net carbon dioxide reduction compared to other plant *** also clarifies the purpose of using both software tools to achieve a comprehensive understanding of both technical and economic aspects.

关键词： Helioscope solar photovoltaic PV GIS performance land coverage economics

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Review:Botnet detection techniques: review, future trends, and issue

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Journal of Zhejiang University-Science C(Computers and Electronics) 2014年第11期15卷 943-983页

作者： ahmad KARIM Rosli bin SALLEH Muhammad SHIRAZ Syed Adeel Ali SHAH Irfan AWAN Nor Badrul ANUAR Faculty of Computer Science and Information Technology University of Malaya Kuala Lumpur Malaysia Department of Computer Science University of Bradford Bradford BD7 1DP UK

In recent years, the Internet has enabled access to widespread remote services in the distributed computing environment; however, integrity of data transmission in the distributed computing platform is hindered by a number of security issues. For instance, the botnet phenomenon is a prominent threat to Internet security, including the threat of malicious codes. The botnet phenomenon supports a wide range of criminal activities, including distributed denial of service(DDoS) attacks, click fraud, phishing, malware distribution, spam emails, and building machines for illegitimate exchange of information/materials. Therefore, it is imperative to design and develop a robust mechanism for improving the botnet detection, analysis, and removal process. Currently, botnet detection techniques have been reviewed in different ways; however, such studies are limited in scope and lack discussions on the latest botnet detection techniques. This paper presents a comprehensive review of the latest state-of-the-art techniques for botnet detection and figures out the trends of previous and current research. It provides a thematic taxonomy for the classification of botnet detection techniques and highlights the implications and critical aspects by qualitatively analyzing such techniques. Related to our comprehensive review, we highlight future directions for improving the schemes that broadly span the entire botnet detection research field and identify the persistent and prominent research challenges that remain open.

关键词： Botnet detection Anomaly detection Network security Attack Defense Taxonomy

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OBSO Based Fractional PID for MPPT-Pitch Control of Wind Turbine Systems

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Computers, Materials & Continua 2022年第5期71卷 4001-4017页

作者： Ibrahim M.Mehedi Ubaid M.Al-Saggaf Mahendiran T.Vellingiri ahmad H.Milyani Nordin bin Saad Nor Zaihar bin Yahaya Department of Electrical and Computer Engineering(ECE) King Abdulaziz UniversityJeddah21589Saudi Arabia Center of Excellence in Intelligent Engineering Systems(CEIES) King Abdulaziz UniversityJeddah21589Saudi Arabia Department of Electrical&Electronics Engineering Universiti Teknologi PETRONASMalaysia

In recent times,wind energy receives maximum attention and has become a significant green energy source *** wind turbine(WT)entered into several domains such as power electronics that are employed to assist the connection process of a wind energy system and *** turbulent characteristics of wind profile along with uncertainty in the design of WT make it highly challenging for prolific power *** pitch control angle is employed to effectively operate the WT at the above nominal wind ***,the pitch controller needs to be intelligent for the extraction of sustainable secure energy and keep WTs in a safe operating *** achieve this,proportional–integral–derivative(PID)controllers are widely used and the choice of optimal parameters in the PID controllers needs to be properly *** this motivation,this paper designs an oppositional brain storm optimization(OBSO)based fractional order PID(FOPID)design for sustainable and secure energy in WT *** proposed model aims to effectually extract the maximum power point(MPPT)in the low range of weather conditions and save the WT in high wind regions by the use of pitch *** OBSO algorithm is derived from the integration of oppositional based learning(OBL)concept with the traditional BSO algorithm in order to improve the convergence rate,which is then applied to effectively choose the parameters involved in the FOPID *** performance of the presented model is validated on the pitch control of a 5 MW WT and the results are examined under different *** simulation outcomes ensured the promising characteristics of the proposed model over the other methods.

关键词： Wind turbine wind energy pitch control brain storm optimization PID controller maximum power point

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Deep Image Restoration Model: A Defense Method Against Adversarial Attacks

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Computers, Materials & Continua 2022年第5期71卷 2209-2224页

作者： Kazim Ali Adnan N.Quershi ahmad Alauddin bin Arifin Muhammad Shahid Bhatti Abid Sohail Rohail Hassan Department of Information Technology University of Central PunjabLahore54000Pakistan Department of Communication Technology and Network Faculty of Computer Science and Information TechnologyUniversity Putra MalaysiaSalengor43400Malaysia Department of Computer Science Comsats University IslamabadLahore Campus54000Pakistan Othman Yeop Abdullah Graduate School of Business University Utara MalaysiaKuala Lumpur50300Malaysia

These days,deep learning and computer vision are much-growing fields in this modern world of information *** learning algorithms and computer vision have achieved great success in different applications like image classification,speech recognition,self-driving vehicles,disease diagnostics,and many *** success in various applications,it is found that these learning algorithms face severe threats due to adversarial *** examples are inputs like images in the computer vision field,which are intentionally slightly changed or *** changes are humanly *** are misclassified by a model with high probability and severely affects the performance or *** this scenario,we present a deep image restoration model that restores adversarial examples so that the target model is classified correctly *** proved that our defense method against adversarial attacks based on a deep image restoration model is simple and state-of-the-art by providing strong experimental results *** have used MNIST and CIFAR10 datasets for experiments and analysis of our defense *** the end,we have compared our method to other state-ofthe-art defense methods and proved that our results are better than other rival methods.

关键词： Computer vision deep learning convolutional neural networks adversarial examples adversarial attacks adversarial defenses

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Magnetic,thermal stability and dynamic mechanical properties of beta isotactic polypropylene/natural rubber blends reinforced by NiZn ferrite nanoparticles

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Defence Technology（防务技术） 2019年第6期15卷 958-963页

作者： Lih-Jiun Yu Sahrim Hj ahmad Ing Kong Mouad ATarawneh Shamsul Bahri bin Abd Razak Elango Natarajan Chun Kit Ang Department of Mechanical Engineering Faculty of EngineeringTechnology and Built EnvironmentUCSI UniversityNo 1Jalan Menara GadingUCSI Heights(Taman Connaught)Cheras56000Kuala LumpurMalaysia School of Applied Physics Faculty of Science and TechnologyUniversity Kebangsaan Malaysia43600BangiSelangor Darul EhsanMalaysia School of Engineering and Mathematical Sciences La Trobe UniversityBundooraVIC3086Australia Department of Physics College of ScienceAl-Hussein Bin Talal UniversityP.O Box 20Ma'anJordan Department of Food Science and Technology University Malaysia TerengganuKuala NerusTerengganuMalaysia

The dispersion of magnetic nanoparticles in matrix is crucial to ensure optimum performance of the *** difficulty level of achieving good dispersion is further increase when a multi-phases of matrix is present.A pre-coating technique of magnetic nanoparticles with polypropylene using ball-mill prior to melt-blending process was employed to prepare a multi-phases thermoplastic natural rubber *** effect of filler loading(2 wt%-10 wt%) on morphology,structure,magnetic properties,thermal stability and dynamic mechanical properties of the composites were *** was found that the NiZn ferrite nanoparticles act as nucleating agent to form beta isostatic polypropylene thermoplastic *** composites’ magnetic properties are directly dependent on the filler *** dispersion of magnetic fillers in polymer matrix plays role in affecting the magnetic properties and thermal *** preference of filler to locate at amorphous phase has distorted the chain orientation of natural rubber and ***,the polymorphism and crystallinity of the matrix varied as the filler loading increased,affecting the dynamic mechanical *** was found that 8 wt% NiZn nanocomposite exhibits highest E’ and tanδ,indicating the dynamic mechanical properties of NiZn nanocomposite are affected by β-phase degree.

关键词： Magnetic Thermoplastic natural rubber Nanoparticles Composites

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