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Numerical simulation of sanding using a coupled hydro-mechanical sand erosion model

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Journal of Rock Mechanics and Geotechnical Engineering 2020年第4期12卷 811-820页

作者： Majid Fetrati Ali pak Department of Civil Engineering Sharif University of TechnologyTehranIran

Mechanical failure of materials adjacent to the production cavity and material disaggregation caused by fluid drag are considered as the most important parameters that affect sand *** light of such factors,the coupling of two mechanisms-mechanical instability and hydrodynamic erosion-is indispensable in order to model this phenomenon *** paper examines the applicability of a coupled hydro-mechanical erosion criterion for simulating sand production using the finite element *** porous medium was considered fully *** onset of sanding and production of sand were predicted by coupling mechanical failure and subsequent erosion of the grain particles utilizing a sanding *** consider the erosion process,the Papamichos and Stavropoulou(1998)’s sand erosion criterion was incorporated into the finite element *** Lagrangian-Eulerian(ALE)adaptive mesh approach was used to account for large amounts of erosive material ***,in order to address the problem of severe mesh distortion,the“mesh mapping technique”was *** production in a horizontal wellbore and in a field case was simulated to demonstrate capabilities of the proposed *** addition,principal parameters affecting sand production,including in situ stresses,cohesion,perforation orientation,and drawdown were *** results indicated the efficiency of the model used in evaluation of sanding in the *** studies indicated that in situ stresses and formation cohesion could be considered as dominant factors affecting the amount of sand production.

关键词： Sand production Finite element method Sanding criterion Hydro-mechanical coupling

Real-Time Network Intrusion Prevention System Using Incremental Feature Generation

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Computers, Materials & Continua 2022年第1期70卷 1631-1648页

作者： Yeongje Uhm Wooguil pak Research and Business Development Foundation Yeungnam UniversityGyeongsanGyeongbuk38541Korea Department of Information and Communication Engineering Yeungnam UniversityGyeongsanGyeongbuk38541Korea

Security measures are urgently required to mitigate the recent rapid increase in network security *** methods employing machine learning have been researched and developed to detect various network attacks effectively,these are passive approaches that cannot protect the network from attacks,but detect them after the end of the *** such passive approaches cannot provide fundamental security solutions,we propose an active approach that can prevent further damage by detecting and blocking attacks in real time before the session *** proposed technology uses a two-level classifier structure:the first-stage classifier supports real-time classification,and the second-stage classifier supports accurate ***,the proposed approach can be used to determine whether an attack has occurred with high accuracy,even under heavy *** extensive evaluation,we confirm that our approach can provide a high detection rate in real ***,because the proposed approach is fast,light,and easy to implement,it can be adopted in most existing network security ***,we hope to mitigate the limitations of existing security systems,and expect to keep networks faster and safer from the increasing number of cyber-attacks.

关键词： Network intrusion detection network intrusion prevention realtime two-level classifier

An Optimized and Hybrid Framework for Image Processing Based Network Intrusion Detection System

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Computers, Materials & Continua 2022年第11期73卷 3921-3949页

作者： Murtaza Ahmed Siddiqi Wooguil pak Department of Information and Communication Engineering Yeungnam UniversityGyeongsan38541Korea

The network infrastructure has evolved rapidly due to the everincreasing volume of users and *** massive number of online devices and users has forced the network to transform and facilitate the operational necessities of *** these necessities,network security is of prime *** intrusion detection systems(NIDS)are among the most suitable approaches to detect anomalies and assaults on a ***,keeping up with the network security requirements is quite challenging due to the constant mutation in attack patterns by the *** paper presents an effective and prevalent framework for NIDS by merging image processing with convolution neural networks(CNN).The proposed framework first converts non-image data from network traffic into images and then further enhances those images by using the Gabor *** images are then classified using a CNN *** assess the efficacy of the recommended method,four benchmark datasets i.e.,CSE-CIC-IDS2018,CIC-IDS-2017,ISCX-IDS 2012,and NSL-KDD were *** proposed approach showed higher precision in contrast with the recent work on the mentioned ***,the proposed method is compared with the recent well-known image processing methods for NIDS.

关键词： Anomaly detection convolution neural networks deep learning image processing intrusion detection network intrusion detection

A Model for Cross-Domain Opinion Target Extraction in Sentiment Analysis

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Computer Systems Science & Engineering 2022年第9期42卷 1215-1239页

作者： Muhammet Yasin pak Serkan GUNAL Department of Computer Engineering Eskisehir Technical UniversityEskisehirTurkiye

Opinion target extraction is one of the core tasks in sentiment analysison text data. In recent years, dependency parser–based approaches have beencommonly studied for opinion target extraction. However, dependency parsersare limited by language and grammatical constraints. Therefore, in this work, asequential pattern-based rule mining model, which does not have such constraints,is proposed for cross-domain opinion target extraction from product reviews inunknown domains. Thus, knowing the domain of reviews while extracting opinion targets becomes no longer a requirement. The proposed model also revealsthe difference between the concepts of opinion target and aspect, which are commonly confused in the literature. The model consists of two stages. In the firststage, the aspects of reviews are extracted from the target domain using the rulesautomatically generated from source domains. The aspects are also transferredfrom the source domains to a target domain. Moreover, aspect pruning is appliedto further improve the performance of aspect extraction. In the second stage, theopinion target is extracted among the aspects extracted at the former stage usingthe rules automatically generated for opinion target extraction. The proposedmodel was evaluated on several benchmark datasets in different domains andcompared against the literature. The experimental results revealed that the opiniontargets of the reviews in unknown domains can be extracted with higher accuracythan those of the previous works.

关键词： Opinion target extraction aspect extraction sentiment analysis

PML solution of longitudinal wave propagation in heterogeneous media

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Earthquake Engineering and Engineering Vibration 2016年第2期15卷 357-368页

作者： Farzanian M. Arbabi Freydoon pak Ronald International Institute of Earthquake Engineering and Seismology 26 Arghavan St. North Dibajee Farmanieh Tehran Iran Department of Civi Environmental & Architectural Engineering University of Colorado Boulder CO 80309-0428 United States

This paper describes the development of a model for unbounded heterogeneous domains with radiation damping produced by an unphysical wave absorbing layer. The Perfectly Matched Layer（PML） approach is used along with a displacement-based finite element. The heterogeneous model is validated using the closed-form solution of a benchmark problem： a free rod with two-part modulus subjected to a specified time history. Both elastically supported and unsupported semi-infinite rods with different degrees of inhomogeneity and loading are considered. Numerical results illustrate the effects of inhomogeneity on the response and are compared with those for equivalent homogeneous domains. The effects of characteristic features of the inhomogeneous problem, presence of local maxima and cut-off frequency are determined. A degenerate case of a homogeneous semi-infinite rod on elastic foundations is produced by tending the magnitude of the foundation stiffness to zero. The response of the latter is compared with that of a free rod. The importance of proper selection of the PML parameters to highly accurate and efficient results is demonstrated by example problems.

关键词： heterogeneous latter benchmark illustrate validated modulus coordinates inhomogeneous maxima infinite

Canonical Foliations of Certain Classes of Almost Contact Metric Structures

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Acta Mathematica Sinica,English Series 2005年第4期21卷 841-846页

作者： Tae Wan KIM Hong Kyung pak Department of Mathematics Education Silla UniversityPusan617-736.Korea Department of Computer and Information Security Daegu Haany University

The purpose of this paper is to study the canonical foliations of an almost cosymplectic or almost Kenmotsu manifold M in a unified way. We prove that the canonical foliation F defined by the contact distribution is Riemannian and tangentially almost Kahler of codimension 1 and that F is tangentially Kahler if the manifold M is normal. Furthermore, we show that a semi-invariant submanifold N of such a manifold M admits a canonical foliation FN which is defined by the antiinvariant distribution and a canonical cohomology class c（N） generated by a transversal volume form for FN. In addition, we investigate the conditions when the even-dimensional cohomology classes of N are non-trivial. Finally, we compute the Godbillon Vey class for FN.

关键词： Almost α-cosymplectic manifold Almost cosymplectic manifold Almost Kenmotsu manifold Semi-invariant submanifold

不同配筋率下钢筋混凝土板柱节点抗冲切承载力试验研究

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工程力学 2024年第S1期41卷 66-73页

作者：朱大壮黄冰峰朴贤日肖云峰张耀庭陈荣昌华中科技大学土木与水利工程学院武汉430074

为研究纵筋配筋率对普通钢筋混凝土板柱节点抗冲切承载力的影响,制作了4个配筋率分别为0.3%、0.7%、1.2%及1.8%的无腹筋板柱中节点并进行冲切试验,试验结果表明:随着配筋率的增加,板柱节点的初始刚度和极限承载力明显增加,试件的延性降... 详细信息

为研究纵筋配筋率对普通钢筋混凝土板柱节点抗冲切承载力的影响,制作了4个配筋率分别为0.3%、0.7%、1.2%及1.8%的无腹筋板柱中节点并进行冲切试验,试验结果表明:随着配筋率的增加,板柱节点的初始刚度和极限承载力明显增加,试件的延性降低,破坏模式由弯曲破坏逐渐向冲切破坏转变;收集并整理了国内外269个板柱节点冲切试验的数据,通过与采用中国规范、美国规范、欧洲规范和日本规范抗冲切承载力计算公式计算结果的对比分析,进一步说明了在冲切承载力计算公式中考虑纵筋配筋率的必要性;通过对试验数据的回归分析,考虑包含纵筋配筋率在内的主要影响因素,建立了适用于钢筋混凝土无腹筋板柱抗冲切承载力的计算公式。

关键词：板柱节点纵筋配筋率冲切试验抗冲切承载力规范对比拟合分析

High Performance Classification of Android Malware Using Ensemble Machine Learning

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Computers, Materials & Continua 2022年第7期72卷 381-398页

作者： Pagnchakneat C.Ouk Wooguil pak Department of Computer Engineering Keimyung UniversityDaegu42601Korea Department of Information and Communication Engineering Yeungnam UniversityGyeongsanGyeongbuk38541Korea

Although Android becomes a leading operating system in market,Android users suffer from security threats due to *** protect users from the threats,the solutions to detect and identify the malware variant are ***,modern malware evades existing solutions by applying code obfuscation and native *** resolve this problem,we introduce an ensemble-based malware classification algorithm using malware family *** proposed family grouping algorithm finds the optimal combination of families belonging to the same group while the total number of families is fixed to the optimal total *** also adopts unified feature extraction technique for handling seamless both bytecode and native *** propose a unique feature selection algorithm that improves classification performance and time simultaneously.2-gram based features are generated from the instructions and segments,and then selected by using multiple filters to choose most effective *** extensive simulation with many obfuscated and native code malware applications,we confirm that it can classify malwares with high accuracy and short processing *** existing approaches failed to achieve classification speed and detection time ***,the approach can help Android users to keep themselves safe from various and evolving cyber-attacks very effectively.

关键词： Android malware classification family grouping native code obfuscation unified feature extraction

Spectrum and Singular Integrals on a New Weighted Function Space

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Acta Mathematica Sinica,English Series 2018年第11期34卷 1692-1702页

作者： Hee Chul pak Young Ja PARK Department of Mathematics Dankook University Dandae-ro 119 Dongnam-gu Cheonan-si Chungnam 31116 Republic of Korea Department of Mathematics Hoseo University Hoeo-ro 79 Asan-si Chungnam 31499 Republic of Korea

We introduce a new function space that is much finer than the classical Lebesgue spaces, and investigate the continuity and the discontinuity of the Calderon-Zygmund operators on the new weighted spaces. In order to identify the continuity of singular integrals, we prove an interpolation theorem on the new spaces and propose a concept of the spectrum of base functions.

关键词： Function spaces singular integrals interpolation Calderdn Zygmund operators Holder's inequality L log L