• Title/Summary/Keyword: solution in closed-form

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An Analysis for the Efficient Dissemination of Beacon Messages in Vehicle-to-Vehicle (V2V) Communications (자동차 간 통신에서 비컨 메시지의 효율적인 방송을 위한 성능 분석)

  • Nguyen, Hoa-Hung;Bhawiyuga, Adhitya;Jeong, Han-You
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.37 no.6C
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    • pp.483-491
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    • 2012
  • In vehicle-to-vehicle (V2V) communications, each vehicle should periodically disseminate a beacon message including the kinematics information, such as position, speed, steering, etc., so that a neighbor vehicle can better perceive and predict the movement of the vehicle. However, a simple broadcasting of such messages may lead to a low reception probability as well as an excessive delay. In this paper, we attempt to analyze the impact of the following key parameters of the beacon dissemination on the performance of vehicular networks: beacon period, carrier-sensing range, and contention window (CW) size. We first derive a beacon period which is inversely proportional to the vehicle speed. Next, we mathematically formulate the maximum beacon load to demonstrate the necessity of the transmit power control. We finally present an approximate closed-form solution of the optimal CW size that leads to the maximum throughput of beacon messages in vehicular networks.

A computational investigation on flexural response of laminated composite plates using a simple quasi-3D HSDT

  • Draiche, Kada;Selim, Mahmoud M.;Bousahla, Abdelmoumen Anis;Tounsi, Abdelouahed;Bourada, Fouad;Tounsi, Abdeldjebbar;Mahmoud, S.R.
    • Steel and Composite Structures
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    • v.41 no.5
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    • pp.697-711
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    • 2021
  • In this work, a simple quasi 3-D parabolic shear deformation theory is developed to examine the bending response of antisymmetric cross-ply laminated composite plates under different types of mechanical loading. The main feature of this theory is that, in addition to including the transverse shear deformation and thickness stretching effects, it has only five-unknown variables in the displacement field modeling like Mindlin's theory (FSDT), yet satisfies the zero shear stress conditions on the top and bottom surfaces of the plate without requiring a shear correction factor. The static version of principle of virtual work was employed to derive the governing equations, while the bending problem for simply supported antisymmetric cross-ply laminated plates was solved by a Navier-type closed-form solution procedure. The adequacy of the proposed model is handled by considering the impact of side-to-thickness ratio on bending response of plate through several illustrative examples. Comparison of the obtained numerical results with the other shear deformation theories leads to the conclusion that the present model is more accurate and efficient in predicting the displacements and stresses of laminated composite plates.

Modelling of tension-stiffening in bending RC elements based on equivalent stiffness of the rebar

  • Torres, Lluis;Barris, Cristina;Kaklauskas, Gintaris;Gribniak, Viktor
    • Structural Engineering and Mechanics
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    • v.53 no.5
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    • pp.997-1016
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    • 2015
  • The contribution of tensioned concrete between cracks (tension-stiffening) cannot be ignored when analysing deformation of reinforced concrete elements. The tension-stiffening effect is crucial when it comes to adequately estimating the load-deformation response of steel reinforced concrete and the more recently appeared fibre reinforced polymer (FRP) reinforced concrete. This paper presents a unified methodology for numerical modelling of the tension-stiffening effect in steel as well as FRP reinforced flexural members using the concept of equivalent deformation modulus and the smeared crack approach to obtain a modified stress-strain relation of the reinforcement. A closed-form solution for the equivalent secant modulus of deformation of the tensioned reinforcement is proposed for rectangular sections taking the Eurocode 2 curvature prediction technique as the reference. Using equations based on general principles of structural mechanics, the main influencing parameters are obtained. It is found that the ratio between the equivalent stiffness and the initial stiffness basically depends on the product of the modular ratio and reinforcement ratio ($n{\rho}$), the effective-to-total depth ratio (d/h), and the level of loading. The proposed methodology is adequate for numerical modelling of tension-stiffening for different FRP and steel reinforcement, under both service and ultimate conditions. Comparison of the predicted and experimental data obtained by the authors indicates that the proposed methodology is capable to adequately model the tension-stiffening effect in beams reinforced with FRP or steel bars within wide range of loading.

Analytical Method for Bending Moment of Slab-on-Steel-Girder Bridge (강판형교 바닥판 모멘트의 해석기법)

  • Park, Nam Hoi;Choi, Jin Yu;Yu, Chul Soo;Kang, Young Jong
    • Journal of Korean Society of Steel Construction
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    • v.12 no.1 s.44
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    • pp.17-28
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    • 2000
  • The current specifications for bridge decks requires the same amount of upper and lower reinforcement mats. There have been many empirical activities that the partial elimination of upper reinforcing bars was not caused the structural integrity of a deck. A simplified method is derived based on thin plate theory for three and four-girder-span bridge decks. A simplified method for bridge deck considering the effect of girder deflection is proposed based on a closed-form solution that shows good agreement with the results of finite element models. In this research, a new design approach for deck slabs is proposed based on the simplified method. The negative bending moments in a deck can be evaluated with the simplified method based on the position of a wheel load, the aspect ratio and relative stiffness and the span length. This new approach can lead to a significant reduction of the quantity of the top reinforcing steel bars in a deck. Reducing the quantify of the top reinforcement not only reduces the construction costs for bridge decks, but also reduces the corrosion of reinforcement to a minimum.

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Proposal of social commerce model for B2B (B2B 거래 기반의 소셜커머스 모델 소개)

  • Yoo, Soonduck;Kim, Jungihl
    • The Journal of the Institute of Internet, Broadcasting and Communication
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    • v.12 no.6
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    • pp.207-213
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    • 2012
  • With development of IT technology, B2C Social Commerce makes the change from closed type of transaction to the form of an open trading. Also by dramatically reducing the intermediate distribution and removing distribution costs, it provides goods at unbeatable prices to consumers. Depending on the flow of the times, the business-to-business struggles with the difficulty of PRM management and fast promotion of new products. Therefore, it is required B2B Social Commerce, new platform that can collect distribution and consumption firms in one place which is similar to B2C Social Commerce. Unlike the case of B2C social commerce, B2B Social Commerce should have an essential element, Installment payment system to pay over the period without purchase in accordance with the payment paid as a lump sum. B2B Social Commerce model which is introduced in this study will provide the solution of B2B transaction problems, opening up new markets and bring the expansion of the electronic market.

Simplified PAR Reduction Technique for MIMO-OFDM System (MIMO-OFDM 시스템에서 간략화된 PAR 감쇄 기법)

  • Song Hyoung-Kyu;Kook Hyung-Joon
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.30 no.12C
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    • pp.1181-1185
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    • 2005
  • A combining of MIMO signal processing with OFDM is regarded as a promising solution of enhancing the performance of next generation wireless system. Therefore, in this paper, an OFDM-based wireless system employing layered space-time architecture is considered for a high-rate transmission. In the MIMO-OFDM system, we evaluate the PAR performance using the SLM approaches. The investigated SLM scheme for MIMO-OFDM signals selects the transmitted sequence with lowest average PAR over all transmitting antennas and retrieves the side information very accurately at the expense of a slight degradation of the PAR performance. The low probability of false side information can improve the overall detection performance of the MIMO-OFDM system with erroneous side information compared to the ordinary SLM approache, respectively. Also, we provide closed form of the average BER performance in MIMO-OFDM system using analytic approach.

An efficient shear deformation theory with stretching effect for bending stress analysis of laminated composite plates

  • Abbas, Soufiane;Benguediab, Soumia;Draiche, Kada;Bakora, Ahmed;Benguediab, Mohamed
    • Structural Engineering and Mechanics
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    • v.74 no.3
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    • pp.365-380
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    • 2020
  • The focus of this paper is to develop an analytical approach based on an efficient shear deformation theory with stretching effect for bending stress analysis of cross-ply laminated composite plates subjected to transverse parabolic load and line load by using a new kinematic model, in which the axial displacements involve an undetermined integral component in order to reduce the number of unknowns and a sinusoidal function in terms of the thickness coordinate to include the effect of transverse shear deformation. The present theory contains only five unknowns and satisfies the zero shear stress conditions on the top and bottom surfaces of the plate without using any shear correction factors. The governing differential equations and its boundary conditions are derived by employing the static version of principle of virtual work. Closed-form solutions for simply supported cross-ply laminated plates are obtained applying Navier's solution technique, and the numerical case studies are compared with the theoretical results to verify the utility of the proposed model. Lastly, it can be seen that the present outlined theory is more accurate and useful than some higher-order shear deformation theories developed previously to study the static flexure of laminated composite plates.

IBN-based: AI-driven Multi-Domain e2e Network Orchestration Approach (IBN 기반: AI 기반 멀티 도메인 네트워크 슬라이싱 접근법)

  • Khan, Talha Ahmed;Muhammad, Afaq;Abbas, Khizar;Song, Wang-Cheol
    • KNOM Review
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    • v.23 no.2
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    • pp.29-41
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    • 2020
  • Networks are growing faster than ever before causing a multi-domain complexity. The diversity, variety and dynamic nature of network traffic and services require enhanced orchestration and management approaches. While many standard orchestrators and network operators are resulting in an increase of complexity for handling E2E slice orchestration. Besides, there are multiple domains involved in E2E slice orchestration including access, edge, transport and core network each having their specific challenges. Hence, handling of multi-domain, multi-platform and multi-operator based networking environments manually requires specified experts and using this approach it is impossible to handle the dynamic changes in the network at runtime. Also, the manual approaches towards handling such complexity is always error-prone and tedious. Hence, this work proposes an automated and abstracted solution for handling E2E slice orchestration using an intent-based approach. It abstracts the domains from the operators and enable them to provide their orchestration intention in the form of high-level intents. Besides, it actively monitors the orchestrated resources and based on current monitoring stats using the machine learning it predicts future utilization of resources for updating the system states. Resulting in a closed-loop automated E2E network orchestration and management system.

Comparison of methods of approximating option prices with Variance gamma processes (Variance gamma 확률과정에서 근사적 옵션가격 결정방법의 비교)

  • Lee, Jaejoong;Song, Seongjoo
    • The Korean Journal of Applied Statistics
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    • v.29 no.1
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    • pp.181-192
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    • 2016
  • We consider several methods to approximate option prices with correction terms to the Black-Scholes option price. These methods are able to compute option prices from various risk-neutral distributions using relatively small data and simple computation. In this paper, we compare the performance of Edgeworth expansion, A-type and C-type Gram-Charlier expansions, a method of using Normal inverse gaussian distribution, and an asymptotic method of using nonlinear regression through simulation experiments and real KOSPI200 option data. We assume the variance gamma model in the simulation experiment, which has a closed-form solution for the option price among the pure jump $L{\acute{e}}vy$ processes. As a result, we found that methods to approximate an option price directly from the approximate price formula are better than methods to approximate option prices through the approximate risk-neutral density function. The method to approximate option prices by nonlinear regression showed relatively better performance among those compared.

Nonlinear Fluid Forces on Hinged Wavemakers (힌지형 조파기에 작용하는 비선형 파력)

  • Kim, Tae-In;Rocbert T. Hudspeth
    • Journal of Korean Society of Coastal and Ocean Engineers
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    • v.2 no.4
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    • pp.208-222
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    • 1990
  • The nonlinear hydrodynamic pressure force and moment on hinged wavemakers of variable-draft are presented. A closed-form solution (correct to second-order) for the nonlinear wavemaker boundary value problem has been obtained by employing the Stokes perturbation expansion scheme. The physical significance of the second-order contributions to the hydrodynamic pressure moment are examined in detail. Design curves are presented which demonstrate both the magnitude of the second-order nonlinearities and the effects of the variable-draft hinge height. The second-order contributions to the total hydrodynamic force and moment consist of a time-dependent and a steady part. The sum of the first and second-order pressure force and moment show a significant increase over those predicted by linear wavemaker theory. The second-order effects are shown to vary with both relative water depth and wave amplitude. The second-order dynamic effects are relatively more important for hinged wavemakers with shallower drafts.

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