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An iterative approach for modal analysis of solid rocket motor incorporating frequency dependent modulus

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航空动力学报 2013年第2期28卷 452-458页

作者： Muhammad adnan SUN Bing ZHANG Jian-wei Sarosh Ali School of Astronautics Beijing University of Aeronautics and Astronautics

The modulus of viscoelastic materials varies with excitation ***,during modal analysis of frequency dependent materials,a material evaluation frequency is necessary because stiffness cannot be modified during eigenfrequency *** a result,only those vibration modes are accurate,of which eigenfrequency is close to the material evaluation *** order to obtain vibration modes of solid rocket motor(SRM) using material modulus based on frequency which is the same as the eigenfrequency,an iterative approach was *** of the iterative technique show that frequency modes obtained from the method are in complete agreement with the eigenfrequency and material evaluation frequency.

关键词： solid rocket motor viscoelastic materials modal analysis eigenfrequency frequency dependent modulus

Structural and optical analysis of Cr_2N thin films prepared by DC magnetron sputtering

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International Journal of Minerals,Metallurgy and Materials 2015年第2期22卷 197-202页

作者： Shakil Khan A.Mahmood A.Shah Qaiser Raza Muhammad Asim rasheed Ishaq Ahmad Department of Metallurgy and Materials Engineering Pakistan Institute of Engineering and Applied Sciences National Institute of Laser and Optronics (NILOP) National Centre for Physics Quaid-i-Azam University

Chromium nitride （Cr2N） thin films were prepared by a DC magnetron sputtering technique. The deposition temperature was raised from 50 to 300℃, and its influence on the film structure and refractive index was investigated. X-ray diffraction analysis shows that the crystalline strucure of the films transforms from the （101） to （002） oriented hexagonal CrzN phase as the increase of substrate tempera- ture above 50℃, and a highly texatred film grows at 100℃. An empirical relation between the crystalline orientation and infrared active modes of the films is obtained, i.e., the Fourier transform infrared （FTIR） spectrum of the film prepared at 50℃ exhibits only A1 （TO） mode. The prominent peak in the FTIR spectra of the film prepared above 50℃is assigned to the E1 （TO） mode and is correlated with the （002） or c-axis oriented hexagonal wurtzite phase of Cr2N. In the surface analysis of atomic force microscopy, a transformation from the featureless surface to columnar-type morphology is observed with the increase of substrate temperature from 50 to 100℃, exhibiting c-axis oriented crystallite growth. A further increase in substrate temperature to 200℃ causes the c-axis crystallites to merge, resulting in the formation of voids. The refractive index （n） of the deposited films is obtained using spectroscopic ellipsometry.

关键词： chromium nitride thin films magnetron sputtering structural analysis optical analysis refractive index

Automatic Unusual Activities Recognition Using Deep Learning in Academia

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Computers, Materials & Continua 2022年第1期70卷 1829-1844页

作者： Muhammad Ramzan adnan Abid Shahid Mahmood Awan School of Systems and Technology University of Management and TechnologyLahore54782Pakistan Department of Computer Science and Information Technology University of SargodhaSargodha40100Pakistan School of Electronics Computing and MathematicsUniversity of DerbyDerbyUnited Kingdom

In the current era,automatic surveillance has become an active research problem due to its vast real-world applications,particularly for maintaining law and order.A continuous manual monitoring of human activities is a tedious *** use of cameras and automatic detection of unusual surveillance activity has been growing exponentially over the last few *** computer vision techniques have been applied for observation and surveillance of real-world *** research study focuses on detecting and recognizing unusual activities in an academic situation such as examinationhalls,which may help the invigilators observe and restrict the students from cheating or using *** the best of our knowledge,this is the first research work in this area that develops a dataset for unusual activities in the examination and proposes a deep learning model to detect those unusual *** proposed model has been named Automatic Unusual Activity Recognition(AUAR),which employsmotion-based frame extraction approaches to extract key-frames and then applies advanced deep learning Convolutional Neural Network algorithm with diverse *** evaluation using standard performancemeasures confirmthat theAUARmodel outperforms the already proposed approaches for unusual activity *** from evaluating the proposed model on the examination dataset,we also apply AUAR on Violent and Movies datasets,widely used in the relevant literature to detect suspicious *** results reveal that AUAR performs well on various data sets compared to existing state-of-the-art models.

关键词： Deep learning unusual activities examination CNN surveillance human activity recognition

Detection of Lung Nodules on X-ray Using Transfer Learning and Manual Features

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Computers, Materials & Continua 2022年第7期72卷 1445-1463页

作者： Imran Arshad Choudhry adnan N.Qureshi Faculty of Information Technology University of Central PunjabLahorePakistan

The well-established mortality rates due to lung cancers,scarcity of radiology experts and inter-observer variability underpin the dire need for robust and accurate computer aided diagnostics to provide a second *** this end,we propose a feature grafting approach to classify lung cancer images from publicly available National Institute of Health(NIH)chest X-Ray dataset comprised of 30,805 unique *** performance of transfer learning with pre-trained VGG and Inception models is evaluated in comparison against manually extracted radiomics features added to convolutional neural network using custom *** classification with both approaches,Support VectorsMachines(SVM)are *** results from the 5-fold cross validation report Area Under Curve(AUC)of 0.92 and accuracy of 96.87%in detecting lung nodules with the proposed *** is a plausible improvement against the observed accuracy of transfer learning using Inception(79.87%).The specificity of allmethods is>99%,however,the sensitivity of the proposed method(97.24%)surpasses that of transfer learning approaches(<67%).Furthermore,it is observed that the true positive rate with SVM is highest at the same false-positive rate in experiments amongst Random Forests,Decision Trees,and K-Nearest Neighbor ***,the proposed approach can be used in clinical and research environments to provide second opinions very close to the experts’intuition.

关键词： Lungs cancer convolutional neural network hand-crafted feature extraction deep learning classification

Geometrically Nonlinear Deformation Reconstruction Based on iQS4 Elements Using a Linearized Iterative iFEM Algorithm

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Acta Mechanica Solida Sinica 2023年第1期36卷 166-180页

作者： Mengying Li Dawei Jia He Huang Ziyan Wu adnan Kefal School of Mechanics Civil Engineering and ArchitectureNorthwestern Polytechnical UniversityXi’an 710129China Faculty of Engineering and Natural Sciences Sabanci UniversityTuzlaIstanbul 34956Turkey Integrated Manufacturing Technologies Research and Application Center Sabanci UniversityTuzlaIstanbul 34956Turkey

Structural shape monitoring plays a vital role in the structural health monitoring *** inverse finite element method(iFEM)has been demonstrated to be a practical method of deformation reconstruction owing to its unique *** iFEM formulations have been applied to small deformation of structures based on the small-displacement assumption of linear ***,this assumption may be inapplicable to some structures with large displacements in practical ***,geometric nonlinearity needs to be *** this study,to expand the practical utility of iFEM for large displacement monitoring,we propose a nonlinear iFEM algorithm based on a four-node inverse quadrilateral shell element *** the advantage of an iterative iFEM algorithm,a nonlinear response is linearized to compute the geometrically nonlinear deformation reconstruction,like the basic concept of nonlinear FE *** examples are solved to verify the proposed *** is demonstrated that large displacements can be accurately estimated even if the in-situ sensor data includes different levels of randomly generated *** is proven that the nonlinear iFEM algorithm provides a more accurate displacement response as compared to the linear iFEM methodology for structures undergoing large ***,the proposed approach can be utilized as a viable tool to effectively characterize geometrically nonlinear deformations of structures in real-time applications.

关键词： Deformation reconstruction iQS4 element Iterative algorithm Nonlinear iFEM Geometric nonlinearity

Traversable wormhole solutions in the f(R)theories of gravity under the Karmarkar condition

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Chinese Physics C 2022年第9期46卷 276-286页

作者： adnan Malik Fatemah Mofarreh Aqsa Zia Akram Ali Department of Mathematics University of Management and TechnologySialkot CampusPakistan Mathematical Science Department Faculty of Science Princess Nourah bint Abdulrahman University.Riyadh 11546 Saudi Arabia Department of Mathematics College of ScienceKing Khalid University9004 AbhaSaudi Arabia

This paper examines traversable wormhole models in the f(R) theories of gravity by applying the Karmarkar condition. For this purpose, we consider spherically symmetric space-time to examine the structure of wormholes. First, we investigate wormholes and their geometry using the redshift function under various conditions. Subsequently, we discuss the embedding diagram of the upper and lower universe using radial coordinates in two and three-dimensional Euclidean affine space. Three exclusive models are considered for the f(R) theories of gravity,and the radial and tangential pressures are observed. Furthermore, by taking a definite shape function, we observe the behavior of energy conditions. We determine that energy conditions are violated, and their violation is generic and represents the presence of exotic matter. According to Einstein’s field theory, the existence of wormholes is predicated on the occurrence of rare material. Hence, we conclude that our study is more realistic and stable.

关键词： wormhole geometry Karmarkar condition red shift function energy conditions

Advanced tools and methods for single-cell surgery

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Microsystems & Nanoengineering 2022年第2期8卷 1-21页

作者： adnan Shakoor Wendi Gao Libo Zhao Zhuangde Jiang Dong Sun Department of Biomedical Engineering City University of Hong KongHong KongChina State Key Laboratory for Manufacturing Systems Engineering International Joint Laboratory for Micro/Nano Manufacturing and Measurement TechnologiesThe School of Mechanical EngineeringXi'an Jiaotong UniversityXi'anChina

Highly precise micromanipulation tools that can manipulate and interrogate cell organelles and components must be developed to support the rapid development of new cell-based medical therapies,thereby facilitating in-depth understanding of cell dynamics,cell component functions,and disease *** paper presents a literature review on micro/nanomanipulation tools and their control methods for single-cell *** methods specifically based on laser,microneedle,and untethered micro/nanotools are presented in *** limitations of these techniques are also *** biological significance and clinical applications of single-cell surgery are also addressed in this paper.

关键词： manipulation surgery needle

A geocomputational analysis of Twitter activity around different world cities

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Geo-Spatial Information Science 2014年第3期17卷 145-152页

作者： Muhammad adnan Alistair LEAK Paul LONGLEY Department of Geography University College LondonGower StreetLondon WC1E 6BTUK Department of Security and Crime Science University College London35 Tavistock SquareLondon WC1H 9EZUK

The penetration and use of social media services differs from city to *** paper is aimed to provide a comparison of the use of Twitter between different cities of the *** present a temporal analysis of activity on Twitter in 15 *** study consists of two parts:First,we created temporal graphs of the activity in the 15 cities,through which hours of high and low activity could be ***,we created heat map visualizations of the Twitter activities during the period of 19 September 2012–25 September *** heat map visualizations make the periods of intense and sparse activity apparent and provide a snapshot of the activity during the whole year.

关键词： Twitter temporal analysis heat map visualization activity patterns

Locating the Source Regions of the Single and Double-Frequency Microseisms to Investigate the Source Effects on HVSR in Site Effect Analysis

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Journal of Earth Science 2022年第5期33卷 1219-1232页

作者： Zhen Guo Mei Xue adnan Aydin Yu Huang State Key Laboratory of Marine Geology Tongji UniversityShanghai200092China College of Civil Engineering Tongji UniversityShanghai200092China Key Laboratory of Geotechnical and Underground Engineering of the Ministry of Education Tongji UniversityShanghai200092China Shanghai Sheshan National Geophysical Observatory Shanghai201602China Department of Geology and Geological Engineering University of MississippiOxfordMS38677USA

Evaluating the seismic site effect by the ambient noise based horizontal-to-vertical spectral ratio(HVSR)method is strongly affected by the spatial and temporal variations of the ambient noise ***,it is necessary to locate the source regions of ambient noise and investigate the relationships between the source energy and HVSR values at the predominant frequency(HVSRf_(0))of the *** generation mechanisms of the single-and double-frequency microseisms(SFMs,0.05-0.085 Hz and DFMs,0.1-0.5 Hz)in ambient noise are better understood than the noise in other frequency bands and they are dominantly composed of fundamental Rayleigh(Rg)*** this advantage,the recordings of SFMs and DFMs at 30 stations in the east coast region of the United States are used to demonstrate a study on locating their source regions with reasonable certainty and constructing the functional relationship between the HVSRf_(0) and the source energy of SFMs and *** recordings are processed in four sub-frequency bands(Fs)of SF and DF bands and a polarization analysis is carried out to select the ellipsoids approximating the particle motions of Rg *** the probability density functions of the back azimuths of the ellipsoids’semi-major axes are computed for each F and station,and are projected on the ocean to determine their possible source *** regions are further constrained by(1)the correlation coefficients between the SFMs and the WAVEWATCHⅢ(WWⅢ)hindcasts of ocean wave spectra in the SF band,or between the DFMs and the modeled DF energy on ocean surface in the selected time windows in the DF band,(2)the energy contribution defined by(i)the average WWⅢocean wave energy and the ocean bottom topographical gradient in the SF band,or(ii)the average modeled DF energy on ocean surface and a frequency and water depth dependent coefficient measuring the conversion efficiency of DF energy from water to solid earth in the DF band,and(3)the percentile retained energy of

关键词： seismic site effect HVSR single-frequency microseisms double-frequency microseisms polarization analysis geophysics