• Title/Summary/Keyword: Key equation

Search Result 697, Processing Time 0.031 seconds

A New Model and Equation Derived From Surface Tension and Cohesive Energy Density of Coagulation Bath Solvents for Effective Precipitation Polymerization of Acrylonitrile

  • Zhou, You;Xue, Liwei;Yi, Kai;Zhang, Li;Ryu, Seung Kon;Jin, Ri Guang
    • Carbon letters
    • /
    • v.13 no.3
    • /
    • pp.182-186
    • /
    • 2012
  • A new model and resultant equation for the coagulation of acrylonitrile monomers in precipitation polymerization are suggested in consideration of the surface tension (${\gamma}$) and cohesive energy density ($E_{CED}$). The equation was proven to be quite favorable by considering figure fittings from known surface tensions and cohesive energy densities of certain organic solvents. The relationship between scale value of surface tension (${\gamma}$/M) and cohesive energy density of monomers can be obtained by changing the coagulation bath component for effective precipitation polymerization of acrylonitrile in wet spinning.

A Continuous Regional Current-Voltage Model for Short-channel Double-gate MOSFETs

  • Zhu, Zhaomin;Yan, Dawei;Xu, Guoqing;Peng, Yong;Gu, Xiaofeng
    • JSTS:Journal of Semiconductor Technology and Science
    • /
    • v.13 no.3
    • /
    • pp.237-244
    • /
    • 2013
  • A continuous, explicit drain-current equation for short-channel double-gate (DG) MOSFETs has been derived based on the explicit surface potential equation. The model is physically derived from Poisson's equation in each region of operation and adopted in the unified regional approach. The proposed model has been verified with numerical solutions, physically scalable with channel length and gate/oxide materials as well as oxide/channel thicknesses.

Improvement of the Spectral Reconstruction Process with Pretreatment of Matrix in Convex Optimization

  • Jiang, Zheng-shuai;Zhao, Xin-yang;Huang, Wei;Yang, Tao
    • Current Optics and Photonics
    • /
    • v.5 no.3
    • /
    • pp.322-328
    • /
    • 2021
  • In this paper, a pretreatment method for a matrix in convex optimization is proposed to optimize the spectral reconstruction process of a disordered dispersion spectrometer. Unlike the reconstruction process of traditional spectrometers using Fourier transforms, the reconstruction process of disordered dispersion spectrometers involves solving a large-scale matrix equation. However, since the matrices in the matrix equation are obtained through measurement, they contain uncertainties due to out of band signals, background noise, rounding errors, temperature variations and so on. It is difficult to solve such a matrix equation by using ordinary nonstationary iterative methods, owing to instability problems. Although the smoothing Tikhonov regularization approach has the ability to approximatively solve the matrix equation and reconstruct most simple spectral shapes, it still suffers the limitations of reconstructing complex and irregular spectral shapes that are commonly used to distinguish different elements of detected targets with mixed substances by characteristic spectral peaks. Therefore, we propose a special pretreatment method for a matrix in convex optimization, which has been proved to be useful for reducing the condition number of matrices in the equation. In comparison with the reconstructed spectra gotten by the previous ordinary iterative method, the spectra obtained by the pretreatment method show obvious accuracy.

Mathematics teachers' Key Developmental Understandings for teaching equation writing (수학교사의 대수식 쓰기 지도를 위한 발달에 핵심적인 이해)

  • Choi, Yunhyeong;Lee, Soo Jin
    • The Mathematical Education
    • /
    • v.60 no.3
    • /
    • pp.297-319
    • /
    • 2021
  • The present study explored a relationship between mathematical understandings of teachers and ways in which their knowledge transferred in designing lessons for hypothetical students from Gess-Newsome (1999)'s transformative perspective of pedagogical content knowledge. To this end, we conducted clinical interviews with four secondary mathematics teachers of their solving and teaching of equation writing. After analyzing the teacher participants' attention to Key Developmental Understandings (Simon, 2007) in solving equation writing, we sought to understand the relationship between their mathematical knowledge of the problems and mathematical knowledge in teaching the problems to hypothetical students. Two of the four teachers who attended the key developmental understandings solved the problems more successfully than those who did not. The other two teachers had trouble representing and explaining the problems, which involved reasoning with improper fractions or reciprocal relationships between quantities. The key developmental understandings of all four teachers were reflected in their pedagogical actions for teaching the equation writing problems. The findings contribute to teacher education by providing empirical data on the relationship between teachers' mathematical knowledge and their knowledge for teaching particular mathematics.

Design of an Area-efficient DCME Algorithm for High-speed Reed-Solomon Decoder (고속 Reed-Solomon 복호기를 위한 면적 효율적인 DCME 알고리즘 설계)

  • Kang, Sung Jin
    • Journal of the Semiconductor & Display Technology
    • /
    • v.13 no.4
    • /
    • pp.7-13
    • /
    • 2014
  • In this paper, an area-efficient degree-computationless modified Euclidean (DCME) algorithm is presented and implemented for high-speed Reed-Solomon (RS) decoder. The DCME algorithm can be used to solve the key equation in Reed-Solomon decoder to get the error location polynomial and the error value polynomial. A pipelined recursive structure is adopted for reducing the area of key equation solver (KES) block with sacrifice of an amount of decoding latency. For comparisons, KES block for RS(255,239,8) decoder with the proposed architecture is implemented using Verilog HDL and synthesized using Synopsys design tool and 65nm CMOS technology. The synthesis results show that the proposed architecture can be implemented with less gate counts than other existing DCME architectures.

The actuation equation of macro-fiber composite coupled plate and its active control over the vibration of plate and shell

  • Tu, Jianwei;Zhang, Jiarui;Zhu, Qianying;Liu, Fan;Luo, Wei
    • Structural Monitoring and Maintenance
    • /
    • v.5 no.2
    • /
    • pp.297-311
    • /
    • 2018
  • Plate and shell structure is widely applied in engineering, i.e. building roofs, aircraft wings, ship platforms, and satellite solar arrays. Its vibration problem has become increasingly prominent due to the tendency of lightening, upsizing and flexibility. As a new smart material with great actuating force and toughness, macro-fiber composite (MFC) is composed of piezoelectric fiber and epoxy resin basal body, which can be directly pasted onto the surface of plate and shell and is suitable for vibration control. This paper deduces the actuation equation of MFC coupled plate in different boundary conditions, an equivalent finite element modeling method is proposed which uses MFC actuating force as the applied excitation, and on this basis the active control simulation and experiment of MFC over plate and shell structure vibration are accomplished. The results indicate that MFC is able to implement effective control over plate and shell structure vibration in multi-band range. The comparison between experiment and simulation proves that the actuation equation deduced herein, effective and practicable, can be applied into the simulation calculation of MFC vibration control over plate and shell structure.

A new semi-analytical approach for bending, buckling and free vibration analyses of power law functionally graded beams

  • Du, Mengjie;Liu, Jun;Ye, Wenbin;Yang, Fan;Lin, Gao
    • Structural Engineering and Mechanics
    • /
    • v.81 no.2
    • /
    • pp.179-194
    • /
    • 2022
  • The bending, buckling and free vibration responses of functionally graded material (FGM) beams are investigated semi-analytically by the scaled boundary finite element method (SBFEM) in this paper. In the concepts of the SBFEM, the dimension of computational domain can be reduced by one, therefore only the axial dimension of the beam is discretized using the higher order spectral element, which reduces the amount of calculation and greatly improves the calculation efficiency. The governing equation of FGM beams is derived in detail by the means of the principle of virtual work. Compared with the higher-order beam theory, fewer parameters and simpler control equations are used. And the governing equation is transformed into a first-order ordinary differential equation by introducing intermediate variables. Analytical solutions of the governing equation can be obtained by pade series expansion in the direction of thickness. Numerical example are compared with the numerical solutions provided by the previous researchers to verify the accuracy and applicability of the proposed method. The results show that the proposed formulations can quickly converge to the reference solutions by increasing the order of higher order spectral elements, and high accuracy can be achieved by using a small number of the elements. In addition, the influence of the structural sizes, material properties and boundary conditions on the mechanical behaviors of FG beams subjected to different load types is discussed.

On the effect of void ratio and particle breakage on saturated hydraulic conductivity of tailing materials

  • Ma, Changkun;Zhang, Chao;Chen, Qinglin;Pan, Zhenkai;Ma, Lei
    • Geomechanics and Engineering
    • /
    • v.25 no.2
    • /
    • pp.159-170
    • /
    • 2021
  • Particle size of tailings in different areas of dams varies due to sedimentation and separation. Saturated hydraulic conductivity of high-stacked talings materials are seriously affected by void ratio and particle breakage. Conjoined consolidation permeability tests were carried out using a self-developed high-stress permeability and consolidation apparatus. The hydraulic conductivity decreases nonlinearly with the increase of consolidation pressure. The seepage pattern of coarse-particle tailings is channel flow, and the seepage pattern of fine-particle tailings is scattered flow. The change rate of hydraulic conductivity of tailings with different particle sizes under high consolidation pressure tends to be identical. A hydraulic conductivity hysteresis is found in coarse-particle tailings. The hydraulic conductivity hysteresis is more obvious when the water head is lower. A new hydraulic conductivity-void ratio equation was derived by introducing the concept of effective void ratio and breakage index. The equation integrated the hydraulic conductivity equation with different particle sizes over a wide range of consolidation pressures.

Experimental study of internal solitary wave loads on the semi-submersible platform

  • Zhang, Jingjing;Liu, Yi;Chen, Ke;You, Yunxiang;Duan, Jinlong
    • International Journal of Naval Architecture and Ocean Engineering
    • /
    • v.13 no.1
    • /
    • pp.718-733
    • /
    • 2021
  • A prediction method, based on the Morison equation as well as Froude-Krylov formula, is presented to simulate the loads acting on the columns and caissons of the semi-submersible platform induced by Internal Solitary Wave (ISW) respectively. Combined with the experimental results, empirical formulas of the drag and inertia coefficients in Morison equation can be determined as a function of the Keulegan-Carpenter (KC) number, Reynolds number (Re) and upper layer depth h1/h respectively. The experimental and calculated results are compared. And a good agreement is observed, which proves that the present prediction method can be used for analyzing the ISW-forces on the semi-submersible platform. Moreover, the results also demonstrate the layer thickness ratio has a significant effect upon the maximum horizontal forces on the columns and caissons, but both minimum horizontal and vertical forces are scarcely affected. In addition, the incoming wave directions may also contribute greatly to the values of horizontal forces exerted on the caissons, which can be ignored in the vertical force analysis.

Landing Dynamic and Key Parameter Estimations of a Landing Mechanism to Asteroid with Soft Surface

  • Zhao, Zhijun;Zhao, JingDong;Liu, Hong
    • International Journal of Aeronautical and Space Sciences
    • /
    • v.14 no.3
    • /
    • pp.237-246
    • /
    • 2013
  • It is of great significance to utilize a landing mechanism to explore an asteroid. A landing mechanism named ALISE (Asteroid Landing and In Situ Exploring) for asteroid with soft surface is presented. The landing dynamic in the first turning stage, which represents the landing performance of the landing mechanism, is built by a Lagrange equation. Three key parameters can be found influencing the landing performance: the retro-rocket thrust T, damping element damping $c_1$, and cardan element damping $c_2$. In this paper, the retro-rocket thrust T is solved with considering that the landing mechanism has no overturning in extreme landing conditions. The damping element damping c1 is solved by a simplified dynamic model. After solving the parameters T and $c_1$, the cardan element damping $c_2$ is calculated using the landing dynamic model, which is built by Lagrange equation. The validities of these three key parameters are tested by simulation. The results show a stable landing, when landing with the three estimated parameters T, $c_1$, and $c_2$. Therefore, the landing dynamic model and methods to estimate key parameters are reasonable, and are useful for guiding the design of the landing mechanism.