检索结果-南通市图书馆

Large-Scale Traveling Ionospheric Disturbances Observed by GPS Receivers in Antarctica

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Wuhan university Journal of Natural Sciences 2010年第2期15卷 135-142页

作者： MOMANI Mohammad Awad YATIM Baharudin MOHD ALI Mohd Alauddin Institute of Space Science Universiti Kebangsaan Malaysia Bangi 43600 Selangor Malaysia Department of Electrical Electronic and Systems Engineering Faculty of Engineering and Built Environment Universiti Kebangsaan Malaysia Bangi 43600 Selangor Malaysia

The paper examines the propagation direction and velocity of large-scale traveling ionospheric disturbances （LST1Ds） during extreme geomagnetic storms in the 23rd solar cycle （e.g., October 2003 and November 2003 storms） using GPS observations. In the analysis, the time delay between the vertical total electron content （VTEC） structures at Scott Base, McMurdo, Davis and Casey GPS stations and the distance between these stations were the main parameters in the determination of LSTIDs propagation speed and direction. The observations during October and November 2003 storms show obvious time delay between the total electron content （TEC） enhancement signatures at these stations. The time delay suggests a movement of the ionospheric disturbances from higher to lower latitudes during the October storm with a velocity of 800-1 200 m/s and poleward propagation of LSTIDs during the November storm with a ve- locity of 300-400 m/s. The equatorward or poleward expansion of LSTIDs during the October and November 2003 storms is probably caused by the disturbances of the neutral temperature occurring close to the dayside convection throat or by the neutral wind oscillation induced by atmospheric gravity waves （AGW） launched from the aurora region.

关键词： Antarctica GPS ionosphere large-scale traveling iono-spheric disturbance (LSTID) magnetic storm

Polarization Insensitive Broadband Zero Indexed Nano-Meta Absorber for Optical Region Applications

在线全文

学校读者我要写书评

暂无评论

Computers, Materials & Continua 2022年第4期71卷 993-1009页

作者： Ismail Hossain Md Samsuzzaman Ahasanul Hoque Mohd Hafiz Baharuddin Norsuzlin Binti Mohd Sahar Mohammad Tariqul Islam Space Science Center(ANGKASA) Universiti Kebangsaan Malaysia43600UKM BangiSelangorMalaysia Department of Computer and Communication Engineering Faculty of Computer Science and EngineeringPatuakhali Science and Technology UniversityDumki8602PatuakhaliBangladesh Department of Electrical Electronic and Systems EngineeringFaculty of Engineering and Built EnvironmentUniversiti Kebangsaan Malaysia43600UKM BangiSelangorMalaysia

Broadband response metamaterial absorber(MMA)remains a challenge among researchers.A nanostructured new zero-indexed metamaterial(ZIM)absorber is presented in this study,constructed with a hexagonal shape resonator for optical region *** design consists of a resonator and dielectric layers made with tungsten and quartz(Fused).The proposed absorbent exhibits average absorption of more than 0.8972(89.72%)within the visible wavelength of 450–600 nm and nearly perfect absorption of 0.99(99%)at 461.61 *** on computational analysis,the proposed absorber can be characterized as *** developments of ZIM absorbers have demonstrated plasmonic resonance characteristics and a perfect impedance *** incidence obliquity in typically the range of 0◦–90◦both in TE and TM mode with maximum absorbance is more than 0.8972(∼89.72%),and up to 45◦angular stability is suitable for solar cell applications,like exploiting solar *** proposed structure prototype is designed and simulated by studying microwave technology numerical computer simulation(CST)*** finite integration technique(FIT)based simulator CST and finite element method(FEM)based simulator HFSS also helps validate the numerical data of the proposed ZIM *** proposed MMA design is appropriate for substantial absorption,wide-angle stability,absolute invisible layers,magnetic resonance imaging(MRI),color images,and thermal imaging applications.

关键词： Hexagonal resonator loaded star shaped polarization insensitive compact broadband metamaterial absorber optical region applications

Boundary Layer on a Moving Wall with Suction and Injection

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Physics Letters 2007年第8期24卷 2274-2276页

We investigate the boundary-layer flow on a moving permeable plate parallel to a moving stream. The governing equations are solved numerically by a finite-difference method. Dual solutions are found to exist when the ... 详细信息

关键词： coated conductor buffer layer self-epitaxy CeO2

Boundary layer flow over a moving surface in a nanofluid with suction or injection

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Acta Mechanica Sinica 2012年第1期28卷 34-40页

作者： Norfifah Bachok Anuar Ishak Ioan Pop Department of Mathematics and Institute for Mathematical Research Faculty of Science Universiti Putra Malaysia School of Mathematical Sciences Faculty of Science and Technology Universiti Kebangsaan Malaysia Faculty of Mathematics University of Cluj

An analysis is performed to study the heat transfer characteristics of steady two-dimensional boundary layer flow past a moving permeable flat plate in a nanofluid. The effects of uniform suction and injection on the flow field and heat transfer characteristics are numerically studied by using an implicit finite difference method. It is found that dual solutions exist when the plate and the free stream move in the opposite directions. The results indicate that suction delays the boundary layer separation, while injection accelerates it.

关键词： Nanofluid .Moving plate. Boundary layer. Suction/injection - Dual solutions

Geopark Concept as a Tool to Promote Geoheritage Conservation:Case Study from Langkawi Global Geopark,malaysia

在线全文

学校读者我要写书评

暂无评论

地学前缘 2009年第S1期16卷 294-295页

作者： Tanot Unjah Mohd Shafeea Leman Ibrahim Komoo Institute for Environment and Development(LESTARI) University Kebangsaan Malaysia

malaysia embarks on geoheritage conservation in the late 1970’s with initial listing of important geological sites for *** the late 1980’s the idea of having a more systematic approach was discussed that leading towards the introduction of a better described ***,very little of these endeavours and efforts came to reality in protecting and conserving geoheritage in the *** introduction of geopark concept to the country in 2000 has brought positive responses from

关键词： geopark geoheritage conservation geotourism

Formation mechanism and application potential of carbon dots synthesized from palm kernel shell via microwave assisted method

在线全文

学校读者我要写书评

暂无评论

Carbon Resources Conversion 2022年第2期5卷 150-166页

作者： Thivyah Balakrishnan Wei Lun Ang Ebrahim Mahmoudi Abdul Wahab Mohammad Nonni Soraya Sambudi Department of Chemical and Process Engineering Faculty of Engineering&Built EnvironmentUniversiti Kebangsaan Malaysia43600 BangiSelangorMalaysia Centre for Sustainable Process Technology Faculty of Engineering&Built EnvironmentUniversiti Kebangsaan Malaysia43600 BangiSelangorMalaysia Department of Chemical Engineering Universiti Teknologi PETRONAS32610 Seri IskandarPerakMalaysia

The present study systematically investigated the influence of synthesis conditions(duration,reaction medium,and doping concentration)and formation mechanism of carbon dots(CDs)derived from low-cost and abundant biomass palm kernel shell(PKS).Surprisingly,the dopant(urea)did not enhance the photoluminescence of CDs as expected,which could be attributed to the low reactivity between the dopant and PKS *** of synthesis duration from 30 to 120 s clearly indicated the formation mechanism of CDs,involving the stages of dehydration,carbonization,and *** CDs with the highest photoluminescent intensity and quantum yield was obtained at synthesis duration of 90 s,aligned well with the perfect spherical shape of CDs and the synergistic effects of both surface and carbogenic core *** the formation mechanism could be used to optimize the synthesis of CDs,and hence linked to quantum yield and fluorescent *** terms of application potential,the CDs illuminated well as fluorescent ink and in bacteria cells *** potential of CDs as sensing material has also been proven with the quenching of fluorescence in the presence of metal *** linear range for detection of Cu2+ions was 0.1–0.5 mM with a detection limit as low as 0.05 *** signifies the potential of CDs fabricated from PKS as a low-cost and easily available material for Cu2+ions detection in aqueous *** CDs possessed reasonable photo stability as indicated by its consistent fluorescence level even after exposure to UV radiation for a prolonged period of 180 ***,a simple,straightforward,and fast method is developed to synthesis strong blue emissive CDs from green PKS that are potentially suitable for Cu2+ions sensing in real application.

关键词： Carbon dots Microwave radiation Palm kernel shell Cell imaging Metal ions detection

A review of metal nanoparticle-based surface-enhanced Raman scattering substrates for severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)detection Special Collection:Distinguished Australian Researchers

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Aggregate

Aggregate 2023年第5期4卷 1-11页

作者： Norhayati Abu Bakar Nur Nazhifah Yusoff Farah Shahadah Nor Azmi Joseph George Shapter Australian Institute for Bioengineering and Nanotechnology University of QueenslandSt LuciaAustralia Institute of Microengineering and Nanoelectronics Universiti Kebangsaan MalaysiaBangiMalaysia

Monitoring an infectious disease early using highly sensitive and non-invasive techniques is critical for human ***,the development of surfaceenhanced Raman scattering(SERS)for biological detection ideally fits these medical requirements and is rapidly growing as a powerful diagnostic *** can enhance the Raman signal of the target molecule by more than 106 after the adsorption of the molecule on the plasmonic nanostructured *** review provides an overview of the use of gold and silver nanoparticles in SERS substrate designs,followed by the development of these SERS substrates in severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)detection.

关键词： gold nanostars SARS-CoV-2 SERS silver nanostars

Behavioral Intrusion Prediction Model on Bayesian Network over Healthcare Infrastructure

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Computers, Materials & Continua 2022年第8期72卷 2445-2466页

作者： Mohammad Hafiz Mohd Yusof Abdullah Mohd Zin Nurhizam Safie Mohd Satar Faculty of Computer&Mathematical Sciences Universiti Teknologi MARA40450Shah AlamSelangorMalaysia Centre for Software Technology and Management(SOFTAM) Universiti Kebangsaan Malaysia43600BangiSelangor Malaysia

Due to polymorphic nature of malware attack,a signature-based analysis is no longer sufficient to solve polymorphic and stealth nature ofmalware *** the other hand,state-of-the-art methods like deep learning require labelled dataset as a target to train a supervised *** is unlikely to be the case in production network as the dataset is unstructured and has no *** an unsupervised learning is *** study is one of the techniques to elicit traffic ***,studies have shown that existing behavioral intrusion detection model had a few issues which had been parameterized into its common characteristics,namely lack of prior information(p(θ)),and reduced parameters(θ).Therefore,this study aims to utilize the previously built Feature Selection Model subsequently to design a Predictive Analytics Model based on Bayesian Network used to improve the analysis *** Selection Model is used to learn significant label as a target and Bayesian Network is a sophisticated probabilistic approach to predict ***,the results are extended to evaluate detection,accuracy and false alarm rate of the model against the subject matter expert model,Support Vector Machine(SVM),k nearest neighbor(k-NN)using simulated and ground-truth *** ground-truth dataset from the production traffic of one of the largest healthcare provider in malaysia is used to promote realism on the real use case *** have shown that the proposed model consistently outperformed other models.

关键词： Intrusion detection prevention system behavioral malware analysis machine learning in cybersecurity deep learning in intrusion detection system(IDS)and intrusion prevention system(IPS)

Faecal sterols as sewage markers in the Langat River,malaysia:Integration of biomarker and multivariate statistical approaches

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Environmental Sciences 2012年第9期24卷 1600-1608页

作者： Nur Hazirah Adnan Mohamad Pauzi Zakaria Hafizan Juahir Masni Mohd Ali Centre of Excellence for Environmental Forensics Faculty of Environmental StudiesUniversiti Putra Malaysia 43400 SerdangSelangorMalaysia Department of Environmental Sciences Faculty of Environmental StudiesUniversiti Putra Malaysia43400 SerdangSelangorMalaysia School of Environmental and Natural Resource Sciences Faculty of Science and TechnologyUniversiti Kebangsaan Malaysia43600 BangiSelangorMalaysia

The Langat River in malaysia has been experiencing anthropogenic input from urban, rural and industrial activities for many years. Sewage contamination, possibly originating from the greater than three million inhabitants of the Langat River Basin, were examined. Sediment samples from 22 stations （SL01-SL22） along the Langat River were collected, extracted and analysed by GC-MS. Six different sterols were identified and quantified. The highest sterol concentration was found at station SL02 （618.29 ng/g dry weight）, which situated in the Balak River whereas the other sediment samples ranged between 11.60 and 446.52 ng/g dry weight. Sterol ratios were used to identify sources, occurrence and partitioning of faecal matter in sediments and majority of the ratios clearly demonstrated that sewage contamination was occurring at most stations in the Langat River. A multivariate statistical analysis was used in conjunction with a combination of biomarkers to better understand the data that clearly separated the compounds. Most sediments of the Langat River were found to contain low to mid-range sewage contamination with some containing ＇significant＇ levels of contamination. This is the first report on sewage pollution in the Langat River based on a combination of biomarker and multivariate statistical approaches that will establish a new standard for sewage detection using faecal sterols.

关键词： sterols biomarkers surface sediments sewage pollution Langat River principal component analysis