• Title/Summary/Keyword: simplified model

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Dynamic Analysis of the Effect of Base Flexibility on a Spinning Disk Dynamics in a Small Size Disk Drive (소형 디스크 드라이브에 있어서 베이스 강성이 회전하는 원판에 미치는 동적영향 분석)

  • Lee, Sung-Jin;Hong, Soon-Kyo;Cheong, Young-Min
    • Proceedings of the KSME Conference
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    • 2001.06b
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    • pp.601-606
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    • 2001
  • Free vibration analysis was performed for a spinning disk/spindle system mounted on a flexible baseplate. A simplified model was presented considering the effects of the baseplate flexibility on a disk/spindle system, and the equations of motion were derived by the assumed mode method and Lagrange's equation. From the results of the tree vibration analysis, the variations of the natural frequencies were investigated by changing rotating speed, baseplate thickness. They were attributed to the coupling between the flexible modes of the spinning disk/spindle system and the baseplate. This simplified model was used to predict the dynamic characteristics of a small size disk drive. The validity of the simplified model was verified by experiments and FE analysis.

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A Study on the Efficient Occlusion Culling Using Z-Buffer and Simplified Model (Z-Buffer와 간략화된 모델을 이용한 효율적인 가려지는 물체 제거 기법(Occlusion Culling)에 관한 연구)

  • 정성준;이규열;최항순;성우제;조두연
    • Korean Journal of Computational Design and Engineering
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    • v.8 no.2
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    • pp.65-74
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    • 2003
  • For virtual reality, virtual manufacturing system, or simulation based design, we need to visualize very large and complex 3D models which are comprising of very large number of polygons. To overcome the limited hardware performance and to attain smooth realtime visualization, there have been many researches about algorithms which reduce the number of polygons to be processed by graphics hardware. One of these algorithms, occlusion culling is a method of rejecting the objects which are not visible because they are occluded by other objects, and then passing only the visible objects to graphics hardware. Existing occlusion culling algorithms have some shortcomings such as the required long preprocessing time, the limitation of occluder shape, or the need for special hardware implementation. In this study, an efficient occlusion culling algorithm is proposed. The proposed algorithm reads and analyzes Z-buffer of graphics hardware using Microsoft DirectX, and then determines each object's visibility. This proposed algorithm can speed up visualization by reading Z-buffer using DirectX which can access hardware directly compared to OpenGL, by reading only the region to which each object is projected instead of reading the whole Z-Buffer, and the proposed algorithm can perform more exact visibility test by using simplified model instead of using bounding box. For evaluation, the proposed algorithm was applied to very large polygonal models. And smooth realtime visualization was attained.

Verification of SARAX code system in the reactor core transient calculation based on the simplified EBR-II benchmark

  • Jia, Xiaoqian;Zheng, Youqi;Du, Xianna;Wang, Yongping;Chen, Jianda
    • Nuclear Engineering and Technology
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    • v.54 no.5
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    • pp.1813-1824
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    • 2022
  • This paper shows the verification work of SARAX code system in the reactor core transient calculation based on the simplified EBR-II Benchmark. The SARAX code system is an analysis package developed by Xi'an Jiaotong University and aims at the advanced reactor R&D. In this work, a neutron-photon coupled power calculation model and a spatial-dependent reactivity feedback model were introduced. To verify the models used in SARAX, the EBR-II SHRT-45R test was simplified to an ULOF transient with an input flowrate change curve by fitting from reference. With the neutron-photon coupled power calculation model, SARAX gave close results in both power fraction and peak power prediction to the reference results. The location of the hottest assembly from SARAX and reference are the same and the relative power deviation of the hottest assembly is 2.6%. As for transient analysis, compared with experimental results and other calculated results, SARAX presents coincident results both in trend and absolute value. The minimum value of core net reactivity during the transient agreed well with the reported results, which ranged from -0.3$ to -0.35$. The results verify the models in SARAX, which are correct and able to simulate the in-core transient with reliable accuracy.

A Proposal of Simplified Bond Stress-Slip Model between FRP Plank and Cast-In-Place Concrete (FRP 판과 현장타설 콘크리트 사이의 단순 부착모델 제안)

  • Yoo, Seung-Woon
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.12 no.1
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    • pp.65-72
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    • 2008
  • The use of hybrid FRP-concrete structures with a dual purpose of both permanent formwork and reinforcement, has been considered in some studies recently. For the FRP plank and the concrete to act as a composite structural member a satisfactory bond at the interface between the smooth surface of the pultruded plank and the cast-in-place concrete must be developed. Sand was bonded to the pultruded FRP plank using a commercially available epoxy system. In applying general analysis techniques to evaluate the performance of composite structures with FRP stay-in-place forming, it is essential that characteristics of the bond stress-slip relation be identified. In this study I would like to propose a simplified bilinear bond stress-slip model for FRP composite structures.

Simplified Analytical Model for Investigating the Output Power of Solar Array on Stratospheric Airship

  • Zhang, Yuanyuan;Li, Jun;Lv, Mingyun;Tan, Dongjie;Zhu, Weiyu;Sun, Kangwen
    • International Journal of Aeronautical and Space Sciences
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    • v.17 no.3
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    • pp.432-441
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    • 2016
  • Solar energy is the ideal power choice for long-endurance stratospheric airships. The output performance of solar array on stratospheric airship is affected by several major factors: flying latitude, flight date, airship's attitude and the temperature of solar cell, but the research on the effect of these factors on output performance is rare. This paper establishes a new simplified analytical model with thermal effects to analyze the output performance of the solar array. This model consisting of the geometric model of stratospheric airship, solar radiation model and incident solar radiation model is developed using MATLAB computer program. Based on this model, the effects of the major factors on the output performance of the solar array are investigated expediently and easily. In the course of the research, the output power of solar array is calculated for five airship's latitudes of $0^{\circ}$, $15^{\circ}$, $30^{\circ}$, $45^{\circ}$ and $60^{\circ}$, four special dates and different attitudes of five pitch angles and four yaw angles. The effect of these factors on output performance is discussed in detail. The results are helpful for solving the energy problem of the long endurance airship and planning the airline.

Collapse Analysis of Simplified Vehicle Structure Models using Finite Element Limit Analysis (유한요소 극한해석을 이용한 단순체체모델의 붕괴거동해석)

  • Kim, H. S.;Huh, H.
    • Transactions of the Korean Society of Automotive Engineers
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    • v.6 no.5
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    • pp.1-9
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    • 1998
  • The analysis concerns collapse behavior of framed vehicle models with the change of design parameters at the initial stage of conceptual design. Collapse analysis of a vehicle model with framed structures has been carried out using finite element limit analysis. The analysis makes sequential changes of design parameters from an initial model with frames of uniform section so as to stage then weak parts. As a result of those design changes, the collapse load of a model has been increased and the deflection toward a passenger room has been reduced. The results demonstrate the versatility of finite element limit analysis as a tool that confirms the safety of vehicle models.

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Accelerating CFD-DEM simulation of dilute pneumatic conveying with bends

  • Du, Jun;Hu, Guoming;Fang, Ziqiang;Gui, Wenjie
    • International Journal of Fluid Machinery and Systems
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    • v.8 no.2
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    • pp.84-93
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    • 2015
  • The computational cost is expensive for CFD-DEM simulation, a larger time step and a simplified CFD-DEM model can be used to accelerate the simulation. The relationship between stiffness and overlap in non-linear Hertzian model is examined, and a reasonable time step is determined by a new single particle test. The simplified model is used to simulate dilute pneumatic conveying with different types of bends, and its applicability is verified by compared with the traditional model. They are good agreement in horizontal-vertical case and vertical-horizontal case, and show a significant differences in horizontal-horizontal case. But the key features of particle rope formed in different types of bends can be obtained by both models.

Slewing maneuver control of flexible space structure using adaptive CGT

  • Shimada, Yuzo
    • 제어로봇시스템학회:학술대회논문집
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    • 1995.10a
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    • pp.47-50
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    • 1995
  • This paper concerns an adaptive control scheme which is an extension of the simplified adaptive control. Originally, the SAC approach was developed based on the command generator tracker (CGT) theory for perfect model tracking. An attractive point of the SAC is that a control input can be synthesized without any prior knowledge about plant structure. However, a feedforward dynamic compensator of the CGT is removed from the basic structure of the SAC. This deletion of the compensator makes perfect model tracking difficult against even a step input. In this paper, an adaptive control system is redesigned to achieve perfect model tracking for as long as possible by reviving the dynamic compensator of the CGT. The proposed method is applied to slewing control of a flexible space structure and compared to the SAC responses.

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Numerical investigation of segmental tunnel linings-comparison between the hyperstatic reaction method and a 3D numerical model

  • Do, Ngoc Anh;Dias, Daniel;Oreste, Pierpaolo
    • Geomechanics and Engineering
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    • v.14 no.3
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    • pp.293-299
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    • 2018
  • This paper has the aim of estimating the applicability of a numerical approach to the Hyperstatic Reaction Method (HRM) for the analysis of segmental tunnel linings. For this purpose, a simplified three-dimensional (3D) numerical model, using the $FLAC^{3D}$ finite difference software, has been developed, which allows analysing in a rigorous way the effect of the lining segmentation on the overall behaviour of the lining. Comparisons between the results obtained with the HRM and those determined by means of the simplified 3D numerical model show that the proposed HRM method can be used to investigate the behaviour of a segmental tunnel lining.

Evaluation of Performance and Development of Control Method of a New Electric Power Steering System(EPS-TT) (새로운 전동식 동력 조향 장치 (EPS-TT)의 성능 평가 및 제어방법 개발)

  • 송정훈;부광석;이종일
    • Transactions of the Korean Society of Automotive Engineers
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    • v.12 no.5
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    • pp.154-161
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    • 2004
  • A new column type electric power steering system (EPS-TT) is proposed in this study. The remarkable features of EPS-TT are its opto-isolated torque sensor and assist torque control methodology. EPS-TT uses a uni-directional motor and two clutches. Full order and simplified models for EPS-TT are developed to evaluate the EPS-TT. A full car model is also used to investigate the vehicle responses. A PID control logic is designed to control the torque of the assist motor. Various sinusoidal inputs are applied to the system and the resulting performances are analyzed. The results prove that the performances achieved by the EPS-TT are improved compared to those of a conventional EPS-TT across the frequency domain. In addition, it is inexpensive and easy to control the motor. The results of the full order steering system model are similar to those simplified model, but the vehicle responses are slightly different.