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气吸式圆盘白萝卜播种机设计与试验
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作者 尹家巧 李骅 +2 位作者 齐新丹 孙新平 马云龙 《农机化研究》 北大核心 2025年第1期148-156,共9页
针对目前白萝卜种子尺寸小、流动性差、形状不规则导致播种机吸种效果差、漏播率和重播率高等情况,设计了一款气吸式圆盘白萝卜播种机。通过对播种机结构组成和工作原理的分析,计算吸附单粒种子的受力情况,建立了力学模型,并得到单粒最... 针对目前白萝卜种子尺寸小、流动性差、形状不规则导致播种机吸种效果差、漏播率和重播率高等情况,设计了一款气吸式圆盘白萝卜播种机。通过对播种机结构组成和工作原理的分析,计算吸附单粒种子的受力情况,建立了力学模型,并得到单粒最小吸附负压值;通过各级链数转动比,确定了播种机地轮与排种器链数关系。通过对吸种过程DEM-CFD耦合仿真单因素试验,计算确定播种机中排种器关键结构参数最优范围,即排种盘转速为1~2 rad/s、风机负压为4~5 kPa、吸孔直径为2.4~2.8 mm;并在此基础上进行田间试验,以排种盘转速、风机负压、吸孔直径为试验因素,以播种间距合格率指标、漏播率指标、重播率指标为评价标准,进行三因素三水平正交试验。利用Design-Expert软件构造数学回归方程和响应曲面模型,分析了各个参数对播种合格率指标的影响变化,并利用软件最优化模块,确定了结构参数最优组合,即排种盘转速为1.3 rad/s、风机负压为4.6 kPa、吸孔直径为2.5 mm。田间试验结果表明:播种行距合格率指标为92.35%,漏播率指标为3.97%,重播率指标为3.68%,满足白萝卜精量播种的农艺要求。 展开更多
关键词 气吸播种机 耦合仿真 田间试验 正交试验 白萝卜
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柔性条式疏花执行装置试验研究
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作者 冯生 张秀花 +3 位作者 孔德刚 陈磊 朱欣悦 魏华杰 《农机化研究》 北大核心 2025年第2期122-130,共9页
疏花可以调整果树负载量,是影响果树产量和质量的重要因素。为研究机械疏花效果及其影响因素,采用自主研发的柔性条式疏花机执行装置对桃花进行试验,选取橡胶和尼龙两种材料的疏花条,以疏花条轴向间距、疏花条列数、主轴转速、工作模式... 疏花可以调整果树负载量,是影响果树产量和质量的重要因素。为研究机械疏花效果及其影响因素,采用自主研发的柔性条式疏花机执行装置对桃花进行试验,选取橡胶和尼龙两种材料的疏花条,以疏花条轴向间距、疏花条列数、主轴转速、工作模式为试验因素,以疏花指数来评价疏花效果,并优化了装置的工作参数。结果表明:若采用尼龙疏花,疏花轴转速为400 r/min、疏花条列数为4、工作模式为冠内垂直、疏花条轴向间距为5 cm时效果最优;若采用胶条疏花,疏花轴转速为450 r/min、疏花条列数为4、工作模式为冠外平行、疏花条轴向间距为4 cm时效果最优。经试验验证,设计满足疏花的工作要求,为柔性条式疏花机的研发提供了理论依据。 展开更多
关键词 桃树疏花 疏花机 柔性条式 参数优化 正交试验
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TAYLOR SERIES AND ORTHOGONALITY OF THE OCTONION ANALYTIC FUNCTIONS 被引量:12
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作者 李兴民 彭立中 《Acta Mathematica Scientia》 SCIE CSCD 2001年第3期323-330,共8页
The Taylor series of the Octonion analytic function is given. And the orthogonal formula for the Octonion analytic functions is also obtained.
关键词 OCTONION O-analytic function Taylor series orthogonality
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On Frequency Sensitivity and Mode Orthogonality of Flexible Robotic Manipulators 被引量:5
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作者 Fei-Yue Wang Yanqing Gao 《IEEE/CAA Journal of Automatica Sinica》 SCIE EI 2016年第4期394-397,共4页
This paper presents sensitivity analysis of vibration frequencies of flexible manipulators with respect to variations of systems parameters such as rotational inertia of hub, and mass, moment, and side of tip load. Bo... This paper presents sensitivity analysis of vibration frequencies of flexible manipulators with respect to variations of systems parameters such as rotational inertia of hub, and mass, moment, and side of tip load. Both Euler-Bernoulli and Timoshenko dynamical models of flexible manipulators are discussed. By using variational method, sensitivity indices are obtained with explicit expressions for measuring the sensitivity of frequencies. Based on variational formulations, a novel method for deriving the orthogonal relations among vibration modal shape functions of flexible manipulators is introduced. With this method, the orthogonal relations can be derived easily without invoking the tedious process of differentiation and integration by part, as commonly used in their derivation. © 2014 Chinese Association of Automation. 展开更多
关键词 Dielectric waveguides Flexible manipulators MANIPULATORS Orthogonal functions Vibration analysis
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The effect of wave function orthogonality on the simultaneous ionization and excitation of helium 被引量:1
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作者 刘丽娟 贾昌春 +2 位作者 张立民 陈姣姣 陈长进 《Chinese Physics B》 SCIE EI CAS CSCD 2013年第10期247-251,共5页
Within the framework of the first-order Born approximation, the triple differential cross sections (TDCSs) for simultaneous ionization and excitation of helium are calculated. The wave function of the ejected electr... Within the framework of the first-order Born approximation, the triple differential cross sections (TDCSs) for simultaneous ionization and excitation of helium are calculated. The wave function of the ejected electron is chosen to be orthogonal or non-orthogonal to the wave function of the bound electron before ionization. It is found that the orthogonality has a strong effect on the TDCS, especially when plane waves and Coulomb waves are used to describe the projectile and the ejected electron. 展开更多
关键词 simultaneous ionization and excitation triple differential cross section (TDCS) first-order Bornapproximation orthogonality
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Orthogonality of inductosyn angle-measuring system error and error-separating technology 被引量:1
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作者 任顺清 曾庆双 王常虹 《Journal of Harbin Institute of Technology(New Series)》 EI CAS 2003年第4期376-379,共4页
Round inductosyn is widely used in inertial navigation test equipment, and its accuracy has significant effect on the general accuracy of the equipment. Four main errors of round inductosyn,i.e. the first-order long-p... Round inductosyn is widely used in inertial navigation test equipment, and its accuracy has significant effect on the general accuracy of the equipment. Four main errors of round inductosyn,i.e. the first-order long-period (360°) harmonic error, the second-order long-period harmonic error, the first-order short-period harmonic error and the second-order short-period harmonic error, are described, and the orthogonality of these four kinds of errors is studied. An error separating technology is proposed to separate these four kinds of errors, and in the process of separating the short-period harmonic errors, the arrangement in the order of decimal part of the angle pitch number can be omitted. The effectiveness of the technology proposed is proved through measuring and adjusting the angular errors. 展开更多
关键词 INDUCTOSYN angle measurement error separation orthogonality
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A DYNAMICAL SYSTEM ALGORITHM FOR SOLVING A LEAST SQUARES PROBLEM WITH ORTHOGONALITY CONSTRAINTS 被引量:1
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作者 黄建国 叶中行 徐雷 《Journal of Shanghai Jiaotong university(Science)》 EI 2001年第1期81-85,88,共6页
This paper introduced a dynamical system (neural networks) algorithm for solving a least squares problem with orthogonality constraints, which has wide applications in computer vision and signal processing. A rigorous... This paper introduced a dynamical system (neural networks) algorithm for solving a least squares problem with orthogonality constraints, which has wide applications in computer vision and signal processing. A rigorous analysis for the convergence and stability of the algorithm was provided. Moreover, a so called zero extension technique was presented to keep the algorithm always convergent to the needed result for any randomly chosen initial data. Numerical experiments illustrate the effectiveness and efficiency of the algorithm. 展开更多
关键词 orthogonality constraint least squares dynamical system
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基于三维正交频分复用的可见光通信系统研究
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作者 莫大龙 文鸿 +2 位作者 陈青辉 刘克雄 叶玮琼 《湖南工业大学学报》 2025年第2期22-27,共6页
为解决调制带宽受限和频率选择性衰落问题,提出了一种基于三维正交频分复用(3D-OFDM)的可见光通信系统,通过三维星座映射,该系统增加了相邻星座点间的最小欧式距离(MED),从而降低了系统的误码率。针对接收机的硬判决易受到可见光信道非... 为解决调制带宽受限和频率选择性衰落问题,提出了一种基于三维正交频分复用(3D-OFDM)的可见光通信系统,通过三维星座映射,该系统增加了相邻星座点间的最小欧式距离(MED),从而降低了系统的误码率。针对接收机的硬判决易受到可见光信道非线性效应和采样频偏干扰的问题,提出了一种基于K均值聚类解调的三维星座解映射方法。结果表明,在误码率为3.8e-3时,与采用16QAM和8QAM调制的2D-OFDM系统相比,所提出的16ary与8ary的3D-OFDM,分别能够实现3 dB和5 dB的信噪比增益;此外,所提出的3D-OFDM系统在峰均功率比(PAPR)方面也有优势,分别降低了0.3 dB和0.4 dB。所提出的3D-OFDM可见光通信系统具有更优的误码性能。 展开更多
关键词 可见光通信 正交频分复用 三维星座 K均值聚类
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Projections,Birkhoff Orthogonality and Angles in Normed Spaces
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作者 CHEN ZHI-ZHI LIN WEI Luo LU-LIN 《Communications in Mathematical Research》 CSCD 2011年第4期378-384,共7页
Let X be a Minkowski plane, i.e., a real two dimensional normed linear space. We use projections to give a definition of the angle Aq(x, y) between two vectors x and y in X, such that x is Birkhoff orthogonal to y i... Let X be a Minkowski plane, i.e., a real two dimensional normed linear space. We use projections to give a definition of the angle Aq(x, y) between two vectors x and y in X, such that x is Birkhoff orthogonal to y if and only if Aq(x,y)=π/2. Some other properties of this angle are also discussed. 展开更多
关键词 PROJECTION NORM Birkhoff orthogonality ANGLE Minkowski plane DUALITY
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A CRITERION FOR ORTHOGONALITY OF REFINABLE FUNCTIONS
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作者 BiNing HuangDaren 《Applied Mathematics(A Journal of Chinese Universities)》 SCIE CSCD 2001年第4期397-401,共5页
In this note, a criterion for orthonormality of refinable functions via characteristic polynomial of a matrix is given.
关键词 Refinable function orthogonality Conjugate quadrature filter characteristic polynomial.
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VARIOUS NOTIONS OF ORTHOGONALITY IN NORMED SPACES
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作者 N.B.OKELO J.O.AGURE P.O.OLECHE 《Acta Mathematica Scientia》 SCIE CSCD 2013年第5期1387-1397,共11页
In this paper, we present various notions and aspects of orthogonality in normed spaces. Characterizations and generalizations of orthogonality are also consid- ered. Results on orthogonality of the range and the kern... In this paper, we present various notions and aspects of orthogonality in normed spaces. Characterizations and generalizations of orthogonality are also consid- ered. Results on orthogonality of the range and the kernel of elementary operators and the operators implementing them also are given. 展开更多
关键词 orthogonality normed space elementary operator
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ON THE METHOD OF ORTHOGONALITY CONDITIONS FOR SOLVING THE PROBLEM OF LARGE DEFLECTION OF CIRCULAR PLATE
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作者 戴世强 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI 1991年第7期617-625,共9页
In this paper, we reexamine the method of successive approximation presented by Prof. Chien Wei-zangfor solving the problem of large deflection of a circular plate, and find that the method could be regarded as the me... In this paper, we reexamine the method of successive approximation presented by Prof. Chien Wei-zangfor solving the problem of large deflection of a circular plate, and find that the method could be regarded as the method of strained parameters in the singular perturbation theory. In terms of the parameter representing the ratio of the center deflection to the thickness of the plate, we make the asymptotic expansions of the deflection, membrane stress and the parameter of load as in Ref. [1], and then give the orthogonality conditions (i.e. the solvability conditions) for the resulting equations, by which the stiffness characteristics of the plate could be determined. It is pointed out that with the solutions for the small deflection problem of the circular plate and the orthogonality conditions, we can derive the third order approximate relations between the parameter of load and the center deflection and the first-term approximation of membrane stresses at the center and edge of the plate without solving the differential equations. For some special cases (i.e. under uniform load, under compound toad, with different boundary conditiors), we deduce the specific expressions and obtain the results in agreement with the previous ones given by Chien Wei-zang, Yeh kai-yuan and Hwang Chien in Refs. [1 - 4J. 展开更多
关键词 circular plate large deflection method of strained parameters orthogonality condition perturbation theory
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A NOTE ON SOBOLEV ORTHOGONALITY FOR LAGUERRE MATRIX POLYNOMIALS
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作者 Zhihui Zhu Zhongkai Li 《Analysis in Theory and Applications》 2007年第1期26-34,共9页
Abstract. Let {L(Ln^(A,λ)(x)}n≥0 be the sequence of monic Laguerre matrix polynomials defined on [0,∞) byLn^(A,λ)(x)=n!/(-λ)^n ∑nk-0(-λ)^k/k!(n-k)!(A+I)n[(A+I)k]^-1x^k,where A ∈ C^r×... Abstract. Let {L(Ln^(A,λ)(x)}n≥0 be the sequence of monic Laguerre matrix polynomials defined on [0,∞) byLn^(A,λ)(x)=n!/(-λ)^n ∑nk-0(-λ)^k/k!(n-k)!(A+I)n[(A+I)k]^-1x^k,where A ∈ C^r×r. It is known that {Ln^(A,λ)(x)}n≥0 is orthogonal with respect to a matrix moment functional when A satisfies the spectral condition that Re(z) 〉 -1 for every z E or(a). In this note we show that forA such that σ(A) does not contain negative integers, the Laguerre matrix polynomials Ln^(A,λ)(x) are orthogonal with respect to a non-diagonal SobolevLaguerre matrix moment functional, which extends two cases: the above matrix case and the known scalar case. 展开更多
关键词 Laguerre matrix polynomial Sobolev orthogonality matrix moment functional
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Decompositions of Symmetry Using Generalized Linear Diagonals-Parameter Symmetry Model and Orthogonality of Test Statistic for Square Contingency Tables
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作者 Kouji Yamamoto Motoki Ohama Sadao Tomizawa 《Open Journal of Statistics》 2013年第6期9-13,共5页
For square contingency tables with ordered categories, the present paper gives several theorems that the symmetry model holds if and only if the generalized linear diagonals-parameter symmetry model for cell probabili... For square contingency tables with ordered categories, the present paper gives several theorems that the symmetry model holds if and only if the generalized linear diagonals-parameter symmetry model for cell probabilities and for cumulative probabilities and the mean nonequality model of row and column variables hold. It also shows the orthogonality of statistic for testing goodness-of-fit of the symmetry model. An example is given. 展开更多
关键词 umulative Probability Global SYMMETRY LINEAR Diagonals-Parameter SYMMETRY Mean Equality Ordinal Category Orthogonal Test Statistic
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Augmented Eigenvector and Its Orthogonality of Linear Multi-rigid-flexibel-body System 被引量:2
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作者 芮筱亭 贠来峰 +1 位作者 王国平 陆毓琪 《Defence Technology(防务技术)》 SCIE EI CAS 2008年第2期100-105,共6页
The orthogonality of eigenvector is a precondition to compute the dynamic responses of linear multi-rigid-flexible-body system using the classical modal analysis method. For a linear multi-rigid-flexible-body system, ... The orthogonality of eigenvector is a precondition to compute the dynamic responses of linear multi-rigid-flexible-body system using the classical modal analysis method. For a linear multi-rigid-flexible-body system, the eigenfunction does not satisfy the orthogonality under ordinary meaning. A new concept--augmented eigenvector is introduced, which is used to overcome the orthogonality problem of eigenvectors of linear multi-rigid-flexible-body system. The constitution method and the orthogonality of augmented eigenvector are expatiated. After the orthogonality of augmented eigenvector is acquired, the coupling of coordinates in dynamics equations can be released, which makes it possible to analyze exactly the dynamic responses of linear multi-rigid-flexible-body system using the classical modal analysis method. 展开更多
关键词 振动波 正交性 特征向量 动力学
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基于动响应数据特征的桥梁结构损伤识别 被引量:2
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作者 杨少冲 张凯 +1 位作者 李有晨 苏胜昔 《建筑结构》 北大核心 2024年第3期134-140,125,共8页
介绍了本征正交分解(Proper Orthogonal Decomposition,POD)的基本原理,探讨了POD在桥梁结构损伤识别中的应用。提出了基于动响应数据特征的桥梁结构损伤识别方法,该识别方法基于POD技术对桥梁结构在不同位置、不同时刻收集到的位移快... 介绍了本征正交分解(Proper Orthogonal Decomposition,POD)的基本原理,探讨了POD在桥梁结构损伤识别中的应用。提出了基于动响应数据特征的桥梁结构损伤识别方法,该识别方法基于POD技术对桥梁结构在不同位置、不同时刻收集到的位移快照矩阵(Snapshot Matrix)进行本征正交分解,得到结构的本征正交模态(POMs),进而构造出损伤指标来识别结构的损伤位置及程度,实现了对桥梁结构损伤的多工况识别。并以保定黄花沟桥为例,通过数值模拟试验,验证了该方法的有效性,结果表明POD能够从空心板桥结构的振动响应数据中提取出结构的本质特征,并且提取过程简单、快捷,可为桥梁结构提供一种有效的损伤识别方法。 展开更多
关键词 响应数据特征 本征正交分解 本征正交模态 损伤识别 健康监测
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AN IMPLICIT SOLUTION OF BI-PENALTY APPROXIMATION WITH ORTHOGONALITY PROJECTION FOR THE NUMERICAL SIMULATION OF BINGHAM FLUID FLOW
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作者 沙德松 郭杏林 顾元宪 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI 1998年第8期725-734,共10页
An implicit algorithm of Bi-penalty approximation with orthogonality projection for the numerical simulation of Bingham fluid flow problems is proposed in this paper. A Newton fluid flow with two kinds of artificial v... An implicit algorithm of Bi-penalty approximation with orthogonality projection for the numerical simulation of Bingham fluid flow problems is proposed in this paper. A Newton fluid flow with two kinds of artificial viscosity subjected to the inequality constraint is introduced to approximate the Bingham fluid flow. This approach can effectively simulate the Bingham fluid flow with floating rigid cores or fixing rigid cores. 展开更多
关键词 Bingham fluid flow PENALTY orthogonality projection finite element
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国产FPGA上通信基带发端算法设计和系统实现 被引量:1
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作者 李铭 杨明昕 +1 位作者 穆鹏程 张翠翠 《实验技术与管理》 CAS 北大核心 2024年第2期135-145,共11页
该文针对国产FPGA上通信基带算法及相关信号处理算法IP核匮乏现状,设计了基于紫光Logos系列FPGA器件的通信基带发端算法;在紫光FPGA缺乏FIR IP核的情况下,经优化设计实现了仅用7个乘法器的60阶FIR成型滤波器;搭建收发测试环境对设计的... 该文针对国产FPGA上通信基带算法及相关信号处理算法IP核匮乏现状,设计了基于紫光Logos系列FPGA器件的通信基带发端算法;在紫光FPGA缺乏FIR IP核的情况下,经优化设计实现了仅用7个乘法器的60阶FIR成型滤波器;搭建收发测试环境对设计的发端系统进行了测试。测试结果表明,所设计的基于正交调制的发端基带算法和基带系统性能达到主流水平的技术指标要求,实现了首批通信算法和通信系统在国产FPGA器件上的应用。 展开更多
关键词 国产FPGA 通信基带 正交调制 FIR优化
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基于离散元法的茶叶抖筛机结构参数优化与试验 被引量:3
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作者 李兵 朱勇 +3 位作者 方赛弟 方立旭 朱焕成 邹亚刚 《农业工程学报》 EI CAS CSCD 北大核心 2024年第5期337-343,共7页
茶叶抖筛机是茶叶精加工的关键装备,传统抖筛装备主要通过经验设计,筛分性能较差,主要表现在筛净率较低、误筛率较高。该研究结合抖筛机的筛分原理,运用solidworks构建虚拟样机,利用EDEM软件建立茶叶颗粒离散元仿真模型,通过单因素仿真... 茶叶抖筛机是茶叶精加工的关键装备,传统抖筛装备主要通过经验设计,筛分性能较差,主要表现在筛净率较低、误筛率较高。该研究结合抖筛机的筛分原理,运用solidworks构建虚拟样机,利用EDEM软件建立茶叶颗粒离散元仿真模型,通过单因素仿真试验对茶叶颗粒进行动力学分析,结果表明,连杆长度、曲柄半径和筛面倾角是茶叶抖筛机筛分性能的主要影响因素。以筛净率、误筛率为评价指标,设计三因素三水平二次旋转正交试验,并运用DesignExpert软件对试验数据进行回归分析,当连杆长度为1 977 mm、曲柄半径为25 mm、筛面倾角为2.8°时,茶叶筛净率为94.5%、误筛率为4.61%,筛分性能最优。以最优结构参数进行验证试验,筛净率为93.8%,误筛率为4.73%,生产效率为319 kg/h,较优化前筛净率提高3.42%,误筛率降低7.62%,生产效率提高8.87%。该研究结果可为茶叶筛分装备的优化提供理论依据。 展开更多
关键词 茶叶 正交试验 抖筛机 筛分 DEM
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钢纤维喷射砂浆力学性能与流动度多因素正交试验分析 被引量:1
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作者 潘慧敏 张昊 +2 位作者 李梦谊 谢少康 赵庆新 《硅酸盐通报》 CAS 北大核心 2024年第2期466-477,共12页
为探究基体因素对钢纤维喷射砂浆力学性能和流动度的影响,基于正交试验方法对砂浆试件进行了力学性能和流动度测试。结果表明:砂胶比(A)对劈裂抗拉强度的影响较大,对7 d抗压强度有一定的影响,对后期抗折强度影响特别显著;钢纤维掺量(B)... 为探究基体因素对钢纤维喷射砂浆力学性能和流动度的影响,基于正交试验方法对砂浆试件进行了力学性能和流动度测试。结果表明:砂胶比(A)对劈裂抗拉强度的影响较大,对7 d抗压强度有一定的影响,对后期抗折强度影响特别显著;钢纤维掺量(B)对劈裂抗拉强度、前期抗折强度和前中期抗压强度的影响分别为特别显著、显著和不显著;速凝剂掺量(C)对7 d前抗压强度、中后期劈裂抗拉强度影响显著;粉煤灰掺量(D)仅对后期抗压强度的影响显著;前述四种因素掺量对流动度的影响均不显著。由层次分析法得到对抗压强度、抗折强度、劈裂抗拉强度和流动度改善效果最佳的配合比分别为A1B3C3D1、A3B3C1D2、A3B3C3D1、A2B1C1D3,由功效系数法得到综合最佳配合比为A2B3C1D2。钢纤维在基体中起桥接与锚固加强的作用,速凝剂在水化过程中消耗大量的Ca(OH)_(2)并生成钙矾石,促使喷射砂浆早期强度迅速提升。 展开更多
关键词 喷射砂浆 钢纤维 正交试验 功效系数法 微观分析
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