• Title/Summary/Keyword: Classical model

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Simulation of Time-Delay Based Path-Tracking Control of Reusable Launch Vehicle (시간지연기법을 적용한 재사용발사체 유도제어 시뮬레이션)

  • Cho, Woosung;Lee, HyeongJin;Lee, Yeol;Ko, Sangho
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.49 no.8
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    • pp.627-636
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    • 2021
  • This paper deals with a study for the guidance control of reusable launch vehicle. For this purpose, modeling of the equation of motion of a reusable launch vehicle with 6 degrees of freedom was performed. With this model, an optimal re-entry path was created and a path-following guidance control simulation was performed to follow the optimal re-entry path. For the design of the path-following guidance controller, the attitude controller applying a time-delay technique that is resistant to modeling uncertainty, disturbance and failure. And the nonlinear path-following guidance law were used. Guidance control simulation using a classical PD controller was performed and compared with the guidance control simulation of a reusable launch vehicle applying a time delay technique.

An Improved ViBe Algorithm of Moving Target Extraction for Night Infrared Surveillance Video

  • Feng, Zhiqiang;Wang, Xiaogang;Yang, Zhongfan;Guo, Shaojie;Xiong, Xingzhong
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • v.15 no.12
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    • pp.4292-4307
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    • 2021
  • For the research field of night infrared surveillance video, the target imaging in the video is easily affected by the light due to the characteristics of the active infrared camera and the classical ViBe algorithm has some problems for moving target extraction because of background misjudgment, noise interference, ghost shadow and so on. Therefore, an improved ViBe algorithm (I-ViBe) for moving target extraction in night infrared surveillance video is proposed in this paper. Firstly, the video frames are sampled and judged by the degree of light influence, and the video frame is divided into three situations: no light change, small light change, and severe light change. Secondly, the ViBe algorithm is extracted the moving target when there is no light change. The segmentation factor of the ViBe algorithm is adaptively changed to reduce the impact of the light on the ViBe algorithm when the light change is small. The moving target is extracted using the region growing algorithm improved by the image entropy in the differential image of the current frame and the background model when the illumination changes drastically. Based on the results of the simulation, the I-ViBe algorithm proposed has better robustness to the influence of illumination. When extracting moving targets at night the I-ViBe algorithm can make target extraction more accurate and provide more effective data for further night behavior recognition and target tracking.

An Analysis on Employing Developer Profit Incentive to Expedite Open Source Software Development

  • Sohn, Jung-woo;Ko, Yohan;Yun, Younguk
    • Journal of the Korea Society of Computer and Information
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    • v.27 no.11
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    • pp.257-270
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    • 2022
  • This paper analyzes the effect of profit incentives within the setting of bounty open source project. A simple decision-making model based on classical utility maximization is presented for open source developers that includes income effects from the bounty prize. We then simulate the decisions of multiple developers to assess the effect from the bounty prize. Our result shows that learning costs can greatly reduce the software quality improvement benefit from bounty project. It also suggests that open source projects can benefit more when they have multiple small bounty projects than a single large bounty project since it reduces the learning cost and the opportunity cost for the open source developers.

Electronic properties of graphene nanoribbons with Stone-Wales defects using the tight-binding method

  • M.W. Chuan;S.Z. Lok;A. Hamzah;N.E. Alias;S. Mohamed Sultan;C.S. Lim;M.L.P Tan
    • Advances in nano research
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    • v.14 no.1
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    • pp.1-15
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    • 2023
  • Driven by the scaling down of transistor node technology, graphene became of interest to many researchers following the success of its fabrication as graphene nanoribbons (GNRs). However, during the fabrication of GNRs, it is not uncommon to have defects within the GNR structures. Scaling down node technology also changes the modelling approach from the classical Boltzmann transport equation to the quantum transport theory because the quantum confinement effects become significant at sub-10 nanometer dimensions. The aim of this study is to examine the effect of Stone-Wales defects on the electronic properties of GNRs using a tight-binding model, based on Non-Equilibrium Green's Function (NEGF) via numeric computation methods using MATLAB. Armchair and zigzag edge defects are also implemented in the GNR structures to mimic the practical fabrication process. Electronic properties of pristine and defected GNRs of various lengths and widths were computed, including their band structure and density of states (DOS). The results show that Stone-Wales defects cause fluctuation in the band structure and increase the bandgap values for both armchair GNRs (AGNRs) and zigzag GNRs (ZGNRs) at every simulated width. In addition, Stone-Wales defects reduce the numerical computation DOS for both AGNRs and ZGNRs. However, when the lengths of the structures increase with fixed widths, the effect of the Stone-Wales defects become less significant.

Effect of visco-Pasternak foundation on thermo-mechanical bending response of anisotropic thick laminated composite plates

  • Fatima Bounouara;Mohamed Sadoun;Mahmoud Mohamed Selim Saleh;Abdelbaki Chikh;Abdelmoumen Anis Bousahla;Abdelhakim Kaci;Fouad Bourada;Abdeldjebbar Tounsi;Abdelouahed Tounsi
    • Steel and Composite Structures
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    • v.47 no.6
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    • pp.693-707
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    • 2023
  • This article investigates the static thermo-mechanical response of anisotropic thick laminated composite plates on Visco-Pasternak foundations under various thermal load conditions (linear, non-linear, and uniform) along the transverse direction (thickness) of the plate, while keeping the mechanical load constant. The governing equations, which represent the thermo-mechanical behavior of the composite plate, are derived from the principle of virtual displacements. Using Navier's type solution, these equations are solved for the composite plate with simply supported condition. The Visco-Pasternak foundation type is included by considering the impact of the damping on the classical foundation model, which is modeled by Winkler's linear modulus and Pasternak's shear modulus. The excellent accuracy of the present solution is confirmed by comparing the results with those available in the literature. The study investigates the impact of geometric ratios, thermal expansion coefficient ratio, damping coefficient and foundation parameters on the thermo-mechanical flexural response of the composite plate. Overall, this article provides insights into the behavior of composite plates on visco-Pasternak foundations and may be useful for designing and analyzing composite structures in practical applications.

Image Analysis Fuzzy System

  • Abdelwahed Motwakel;Adnan Shaout;Anwer Mustafa Hilal;Manar Ahmed Hamza
    • International Journal of Computer Science & Network Security
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    • v.24 no.1
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    • pp.163-177
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    • 2024
  • The fingerprint image quality relies on the clearness of separated ridges by valleys and the uniformity of the separation. The condition of skin still dominate the overall quality of the fingerprint. However, the identification performance of such system is very sensitive to the quality of the captured fingerprint image. Fingerprint image quality analysis and enhancement are useful in improving the performance of fingerprint identification systems. A fuzzy technique is introduced in this paper for both fingerprint image quality analysis and enhancement. First, the quality analysis is performed by extracting four features from a fingerprint image which are the local clarity score (LCS), global clarity score (GCS), ridge_valley thickness ratio (RVTR), and the Global Contrast Factor (GCF). A fuzzy logic technique that uses Mamdani fuzzy rule model is designed. The fuzzy inference system is able to analyse and determinate the fingerprint image type (oily, dry or neutral) based on the extracted feature values and the fuzzy inference rules. The percentages of the test fuzzy inference system for each type is as follow: For dry fingerprint the percentage is 81.33, for oily the percentage is 54.75, and for neutral the percentage is 68.48. Secondly, a fuzzy morphology is applied to enhance the dry and oily fingerprint images. The fuzzy morphology method improves the quality of a fingerprint image, thus improving the performance of the fingerprint identification system significantly. All experimental work which was done for both quality analysis and image enhancement was done using the DB_ITS_2009 database which is a private database collected by the department of electrical engineering, institute of technology Sepuluh Nopember Surabaya, Indonesia. The performance evaluation was done using the Feature Similarity index (FSIM). Where the FSIM is an image quality assessment (IQA) metric, which uses computational models to measure the image quality consistently with subjective evaluations. The new proposed system outperformed the classical system by 900% for the dry fingerprint images and 14% for the oily fingerprint images.

Using DQ method for vibration analysis of a laminated trapezoidal structure with functionally graded faces and damaged core

  • Vanessa Valverde;Patrik Viktor;Sherzod Abdullaev;Nasrin Bohlooli
    • Steel and Composite Structures
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    • v.51 no.1
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    • pp.73-91
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    • 2024
  • This paper has focused on presenting vibration analysis of trapezoidal sandwich plates with a damaged core and FG wavy CNT-reinforced face sheets. A damage model is introduced to provide an analytical description of an irreversible rheological process that causes the decay of the mechanical properties, in terms of engineering constants. An isotropic damage is considered for the core of the sandwich structure. The classical theory concerning the mechanical efficiency of a matrix embedding finite length fibers has been modified by introducing the tube-to-tube random contact, which explicitly accounts for the progressive reduction of the tubes' effective aspect ratio as the filler content increases. The First-order shear deformation theory of plate is utilized to establish governing partial differential equations and boundary conditions for the trapezoidal plate. The governing equations together with related boundary conditions are discretized using a mapping-generalized differential quadrature (GDQ) method in spatial domain. Then natural frequencies of the trapezoidal sandwich plates are obtained using GDQ method. Validity of the current study is evaluated by comparing its numerical results with those available in the literature. After demonstrating the convergence and accuracy of the method, different parametric studies for laminated trapezoidal structure including carbon nanotubes waviness (0≤w≤1), CNT aspect ratio (0≤AR≤4000), face sheet to core thickness ratio (0.1 ≤ hfhc ≤ 0.5), trapezoidal side angles (30° ≤ α, β ≤ 90°) and damaged parameter (0 ≤ D < 1) are carried out. It is explicated that the damaged core and weight fraction, carbon nanotubes (CNTs) waviness and CNT aspect ratio can significantly affect the vibrational behavior of the sandwich structure. Results show that by increasing the values of waviness index (w), normalized natural frequency of the structure decreases, and the straight CNT (w=0) gives the highest frequency. For an overall comprehension on vibration of laminated trapezoidal plates, some selected vibration mode shapes were graphically represented in this study.

Vibroacoustic response of thin power law indexed functionally graded plates

  • Baij Nath Singh;Vinayak Ranjan;R.N. Hota
    • Steel and Composite Structures
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    • v.50 no.3
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    • pp.299-318
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    • 2024
  • The main objective of this paper is to compute the far-field acoustic radiation (sound radiation) of functionally graded plates (FGM) loaded by sinusoidally varying point load subjected to the arbitrary boundary condition is carried out. The governing differential equations for thin functionally graded plates (FGM) are derived using classical plate theory (CPT) and Rayleigh integral using the elemental radiator approach. Four cases, segregated on power-law index k=0,1,5,10, are studied. A novel approach is illustrated to compute sound fields of vibrating FGM plates using the physical neutral surface with an elemental radiator approach. The material properties of the FGM plate for all cases are calculated considering the power law indexes. An in-house MATLAB code is written to compute the natural frequencies, normal surface velocities, and sound radiation fields are analytically calculated using semi-analytical formulation. Ansys is used to validate the computed sound power level. The parametric effects of the power law index, modulus ratios, different constituent of FGM plates, boundary conditions, damping loss factor on the sound power level, and radiation efficiency is illustrated. This work is the benchmark approach that clearly explains how to calculate acoustic fields using a solid layered FGM model in ANSYS ACT. It shows that it is possible to asymptotically stabilize the structure by controlling the intermittent layers' stiffness. It is found that sound fields radiated by the elemental radiators approach in MATLAB, ANSYS and literatures are in good agreement. The main novelty of this research is that the FGM plate is analyzed in the low-frequency range, where the stiffness-controlled region governs the whole analysis. It is concluded that a clamped mono-ceramic FGM plate radiates a lesser sound power level and higher radiation efficiency than a mono-metallic or metal-rich FGM plate due to higher stiffness. It is found that change in damping loss factor does not affect the same constituents of FGM plates but has significant effects on the different constituents of FGM plates.

Do Innovation and Relative Advantage Affect the Actual Use of FinTech Services?: An Empirical Study using Classical Attitude Theory (핀테크 서비스의 혁신성과 상대적 장점은 실질이용에 영향을 미칠까?: 고전적 태도이론을 이용한 실증 연구)

  • Se Hun Lim
    • Information Systems Review
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    • v.21 no.3
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    • pp.87-110
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    • 2019
  • The Fintech services provide innovation to financial services users using various mobile devices and computers in wired and wireless communication environments. In this study, we develope a theoretical research framework to explain the psychology of Fintech services users based on a cognitive, affective, and conative framework. Using this framework, this study analyzes the relationships between the cognitive characteristics (i.e., innovation, relative advantage, ease of use, and usefulness), emotional characteristic (i.e., attitude), and behavioral characteristic (i.e., actual use) toward Fintech services users. This study conducted an online survey of people who have experienced using Fintech services. And the data of the collected Fintech services users was analyzed using structural equation model software (i.e., SMART PLS 2.0 M3). The results of the empirical analysis show the relationships between innovation, relative advantage, perceived usefulness, perceived ease of use, attitude, and actual use of Fintech service users. The results of this study provide useful information to improve the practical use of Fintech services users in the Internet of Things (IoT) environment.

AI-driven prediction of linear and nonlinear buckling in nonuniform functionally graded micro-tubes for sports equipment in sports training

  • Yan Li;Mostafa Habibi;Maryam Bagheri
    • Advances in nano research
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    • v.17 no.6
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    • pp.559-574
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    • 2024
  • This study investigates the buckling behavior of axially functionally graded (AFG) non-uniform cylindrical beams with specific applications in sports equipment, using a combination of artificial intelligence (AI) and advanced numerical methods. Unlike traditional approaches, this work employs non-classical size-dependent theory and high-order tube theory to more accurately capture the mechanical responses of non-uniform geometries, which are crucial for optimizing the performance and safety of sports equipment such as poles, racquets, and composite materials used in various athletic applications. The beam under consideration has a non-uniform external surface while maintaining a uniform internal radius, with material properties varying continuously along the beam's length. The governing equations are derived using the nonlocal strain gradient theory in conjunction with Von-Karman's nonlinear theory and high-order cylindrical beam theory. These partial differential equations are solved using the Generalized Differential Quadrature Method (GDQM), a powerful numerical technique known for its high accuracy and computational efficiency. Furthermore, to enhance the predictive capability of the model, the results are tested and trained using a neural network (NN), which provides reliable predictions of buckling behavior under various boundary conditions and material distributions. By integrating artificial intelligence with advanced analytical methods, this research offers a practical framework for accurately predicting buckling in non-uniform cylindrical beams, proving beneficial for both theoretical studies and real-world applications in sports engineering. This approach demonstrates the potential for more efficient design and optimization of sports equipment, enhancing athletic performance and ensuring safety compared to traditional methods.