• Title/Summary/Keyword: Closed-Structure

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Performance of Cationic Guar Gums in Closed Papermaking Systems (고폐쇄화 제지공정에서의 양이온성 구아 검 활용 효과)

  • Ham, Choong-Hyun;Lee, Hak-Lae
    • Journal of Korea Technical Association of The Pulp and Paper Industry
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    • v.40 no.3
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    • pp.1-8
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    • 2008
  • The efficiency of retention systems including compozil-G, hydrocol, compozil-S, and micropolymer under highly closed papermaking system was evaluated using contaminated white waters prepared in the laboratory. Compozil-G and compozil-S performed better in retention than hydrocol and micropolymer systems. This suggested that stronger hydrogen bonding between fiber and guar gum or starch was formed to give stronger flocculation and better retention. Especially compozil-G outperformed compozil-S in retention, and this indicated the presence of stronger interaction between guar and cellulose fibers probably due to their similarity in chemical structure. Two compozil retention systems decreased the cationic demand and COD more effectively than hydrocol and microparticle systems. In particular, compozil-G that uses guar gum was highly effective in decreasing anionic trashes at low dosage.

An Exact Closed-Form Expression for Bit Error Rate of Decode-and-Forward Relaying Using Selection Combining over Rayleigh Fading Channels

  • Bao, Vo Nguyen Quoe;Kong, Hyung-Yun
    • Journal of Communications and Networks
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    • v.11 no.5
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    • pp.480-488
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    • 2009
  • Cooperative transmission is an effective solution to improve the performance of wireless communications over fading channels without the need for physical co-located antenna arrays. In this paper, selection combining is used at the destination instead of maximal ratio combing to optimize the structure of destination and to reduce power consumption in selective decode-and-forward relaying networks. For an arbitrary number of relays, an exact and closed-form expression of the bit error rate (BER) is derived for M-PAM, M-QAM, and M-PSK, respectively, in both independent identically distributed and independent but not identically distributed Rayleigh fading channels. A variety of simulations are performed and show that they match exactly with analytic ones. In addition, our results show that the optimum number of relays depend not only on channel conditions (operating SNRs) but also on modulation schemes which to be used.

SOME REMARKS FOR KÜNNETH FORMULA ON BOUNDED COHOMOLOGY

  • Park, HeeSook
    • Honam Mathematical Journal
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    • v.37 no.1
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    • pp.7-27
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    • 2015
  • Kuneth formula is to compute (co)-homology of $A{\otimes}B$ for known (co)-homology of the complexes A and B. In the ordinary case, this is done by using elementary homological methods in an abelian category. However, when we consider the bounded cochain complex with values in $\mathbb{R}$ and its structure as a real Banach space, the techniques of homological algebra for constructing K$\ddot{u}$nneth type formulas on it are not effective. The most notable facts are the image of a morphism of Banach spaces is not necessarily closed, and also the closed summand of a Banach space need not be a topological direct summand. The main goal of this paper is to construct the theory of K$\ddot{u}$nneth type formula on bounded cohomology with real coefficients in the suitable category of Banach spaces with some restricted conditions.

Bridge-type structures analysis using RMP concept considering shear and bending flexibility

  • Hosseini-Tabatabaei, Mahmoud-Reza;Rezaiee-Pajand, Mohmmad;Mollaeinia, Mahmoud R.
    • Structural Engineering and Mechanics
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    • v.74 no.2
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    • pp.189-199
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    • 2020
  • Researchers have elaborated several accurate methods to calculate member-end rotations or moments, directly, for bridge-type structures. Recently, the concept of rotation and moment propagation (RMP) has been presented considering bending flexibility, only. Through which, in spite of moment distribution method, all joints are free resulting in rotation and moment emit throughout the structure similar to wave motion. This paper proposes a new set of closed-form equations to calculate member-end rotation or moment, directly, comprising both shear and bending flexibility. Furthermore, the authors program the algorithm of Timoshenko beam theory cooperated with the finite element. Several numerical examples, conducted on the procedures, show that the method is superior in not only the dominant algorithm but also the preciseness of results.

A Study on High Reynolds Number Flow in Two-Dimensional Closed Cavity (2차원 밀폐 캐비티의 고레이놀즈수 흐름에 관한 연구)

  • 최민선;송치성;이영호
    • Journal of Advanced Marine Engineering and Technology
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    • v.20 no.3
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    • pp.101-109
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    • 1996
  • Two-dimensional lid-driven closed flows within square cavity were studied numerically for four Reynolds numbers : $10^4$, 3$\times10^4$, 5$\times10^4$ and 7.5$\times10^4$. A convective difference scheme to maintain the same spatial accurary by irregular grid correction is adopted by applying the interior division principle. Grid number is $80\times80$and its minimum size is about 1/400 of the cavity height. At Re=$10^4$, periodic migration of small eddies appearing in corner separation region and its temporal sinusoidal fluctuation are represented. At three higher Reynolds numbers(3$\times10^4$, 5$\times10^4$ and 7.5$\times10^4$), an organizing structure of four consecutive vorticles at two lower corners is revealed from time-mean flow patterns. But, instantaneous flow characteristics show very random unsteady fluctuation mainly due to the interaction between rotating shed vortices and stationary eddies within the corners.

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Robust 2-D Object Recognition Using Bispectrum and LVQ Neural Classifier

  • HanSoowhan;woon, Woo-Young
    • Proceedings of the Korean Institute of Intelligent Systems Conference
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    • 1998.10a
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    • pp.255-262
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    • 1998
  • This paper presents a translation, rotation and scale invariant methodology for the recognition of closed planar shape images using the bispectrum of a contour sequence and the learning vector quantization(LVQ) neural classifier. The contour sequences obtained from the closed planar images represent the Euclidean distance between the centroid and all boundary pixels of the shape, and are related to the overall shape of the images. The higher order spectra based on third order cumulants is applied to tihs contour sample to extract fifteen bispectral feature vectors for each planar image. There feature vector, which are invariant to shape translation, rotation and scale transformation, can be used to represent two0dimensional planar images and are fed into a neural network classifier. The LVQ architecture is chosen as a neural classifier because the network is easy and fast to train, the structure is relatively simple. The experimental recognition processes with eight different hapes of aircraft images are presented to illustrate the high performance of this proposed method even the target images are significantly corrupted by noise.

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Fabrication of Al 6061 Foamable Precursor by Powder Metallurgical and Induction Heating Method (P/M법과 유도가열 공정을 이용한 발포용 6061 Al 합금 프리커서 제조)

  • 윤성원;강충길
    • Transactions of Materials Processing
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    • v.12 no.5
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    • pp.457-464
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    • 2003
  • In the powder compact melting technique, proper precursor fabrication is very important because density distribution after foaming and foamability are determined during precursor fabrication process. The fabrication of the precursor has to be performed very carefully because any residual porosity or other defects will lead to poor results in further processing. In order to evaluate the effect of the compaction parameters on the kinetics of the foaming process, a series of experiments were performed. In this study, aluminium foams with a closed cell structure were fabricated by using both the powder compact method and the induction heating process. A proper induction coil was designed to obtain a uniform temperature distribution over the entire cross sectional area of precursor. To establish the foamable precursor fabrication conditions, effects of process parameters such as the titanium hydride content (0.3∼1.5 wt.%), pressing pressure of the foamable precursor (50∼150kN) on the pore morphology were investigated.

A Sliding Mode Control for a Robot Manipulator with closed-chain Structure (폐체인 구조 로봇 머니퓰레이터의 슬라이딩모드 제어)

  • Choi Hyeung Sik;Baek Chagng Yul;Hwang I Chul;Kim Moo Kyung
    • Journal of the Korean Society for Precision Engineering
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    • v.22 no.6 s.171
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    • pp.98-108
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    • 2005
  • Conventional robot manipulators actuated by motors with the speed reducer such as the harmonic drive have weakness in the load capacity, since the speed reducer does not have enough strength. To improve this, a new type of robot actuator based on the four-bar-link mechanism driven by the ball screw was constructed. Also, a new type of revolute robot manipulator composed of the developed actuators was developed. But, modelling errors occur due to the off-set from the nominal model since the exact modeling of the complex inertia variation of the four-bar-link actuator is very difficult. To control the proposed robot along the prescribed trajectory, a sliding mode control algorithm was applied with compensation function for the modeling errors. To show performance of the proposed controller, a computer simulation was performed, and its results was presented.

PERIODIC DISTURBANCE AND NOISE REJECTION METHOD USING HIRBERT TRANSFORM (힐버트 변환을 이용한 주기적인 외란 및 잡음제거)

  • Na, Hee-Seung;Park, Young-Jin
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2000.11a
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    • pp.443-448
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    • 2000
  • In this paper, we propose a novel adaptive feedforward controller for periodic disturbance and noise cancellation, with a frequency tracking capability. It can be added to an existing feedback control system without altering the original closed-loop characteristics, which is based on adaptive algorithm. We introduce novel algorithm "Constrained AFC(adaptive feedforward controller) algorithm" that increase the convergence region regardless of the delay in the closed loop system. In the algorithms, coefficients of the controller are adapted using the residuals of constrained structure which are defined in such a way that the coefficients become time invariant. The proposed algorithm not only estimate the magnitude and phase of the tonal disturbance and noise but also track the frequency of the tone, which changes in quasi-static manner. The frequency tracking algorithm uses the instantaneous frequency approach based on Hilbert transform. A number of computer simulations have been carried out in order to demonstrate the effectiveness of proposed method under various conditions.

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REPRESENTATIONS OF C*-TERNARY RINGS

  • Arpit Kansal;Ajay Kumar;Vandana Rajpal
    • Communications of the Korean Mathematical Society
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    • v.38 no.1
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    • pp.123-135
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    • 2023
  • It is proved that there is a one to one correspondence between representations of C*-ternary ring M and C*-algebra 𝒜(M). We discuss primitive and modular ideals of a C*-ternary ring and prove that a closed ideal I is primitive or modular if and only if so is the ideal 𝒜(I) of 𝒜(M). We also show that a closed ideal in M is primitive if and only if it is the kernel of some irreducible representation of M. Lastly, we obtain approximate identity characterization of strongly quasi-central C*-ternary ring and the ideal structure of the TRO V ⊗tmin B for a C*-algebra B.