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Nonholonomic Theory of Principal-direction Orthonormal Basis for a Layer of Surfaces
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作者 LI Jiayang XIE Xilin 《复旦学报(自然科学版)》 CAS CSCD 北大核心 2024年第4期415-437,442,共24页
In order to carry out tensor analysis in a neighborhood of a reference surface,the principal-direction orthogonal basis accompanying with Lame s coefficients or general curvilinear coordinate systems are widely used.A... In order to carry out tensor analysis in a neighborhood of a reference surface,the principal-direction orthogonal basis accompanying with Lame s coefficients or general curvilinear coordinate systems are widely used.A novel kind of field theory termed as the nonholonomic theory of the Principal-Direction Orthonormal Basis(PDOB)is presented systematically in the present paper,in which the formal Christoffel symbols are related directly to the principal and geodesic curvatures with respect to the principal directions of the surface.Furthermore,a systematic and simple way to determine the curvatures of the surface are presented with some examples.It provides a way to recognize qualitatively the bending property of a surface. 展开更多
关键词 nonholonomic theory principal-direction orthonormal basis principal curvature geodesic curvature
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Development of Ni_(x)/Mg_(1-x)-MOF-74 for highly efficient CO_(2)/N_(2) separation
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作者 ZHANG Xin LI Guoqiang +7 位作者 HONG Mei BAN Hongyan YANG Lixia LIU Xingchen LI Feng Ekaterina Vladimirovna Matus LI Congming LI Lei 《燃料化学学报(中英文)》 EI CAS CSCD 北大核心 2024年第11期1745-1758,共14页
To enhance the separation selectivity of Mg-MOF-74 towards CO_(2) in a CO_(2)/N_(2) mixture,a series of Mg-MOF-74 and Ni_(x)/Mg_(1-x)-MOF-74 adsorbents were prepared by solvothermal synthesis in this paper.It was foun... To enhance the separation selectivity of Mg-MOF-74 towards CO_(2) in a CO_(2)/N_(2) mixture,a series of Mg-MOF-74 and Ni_(x)/Mg_(1-x)-MOF-74 adsorbents were prepared by solvothermal synthesis in this paper.It was found that the adsorption capacity of Mg-MOF-74 for CO_(2) could be effectively increased by optimizing the amount of acetic acid.On this basis,the bimetal MOF-74 adsorbent was prepared by metal modification.The multi-component dynamic adsorption penetration analysis was utilized to examine the CO_(2) adsorption capacity and CO_(2)/N_(2) selectivity of the diverse adsorbent materials.The results showed that Ni0.11/Mg0.89-MOF-74 showed a CO_(2) adsorption capacity of 7.02 mmol/g under pure CO_(2) atmosphere and had a selectivity of 20.50 for CO_(2)/N_(2) under 15% CO_(2)/85%N_(2) conditions,which was 10.2% and 18.02% higher than that of Mg-MOF-74 respectively.Combining XPS,SEM and N_(2) adsorption-desorption characterization analysis,it was attributed to the effect of the more stable unsaturated metal sites Ni into the Mg-MOF-74 on the pore structure and the synergistic interaction between the two metals.Density Functional Theory(DFT)simulations revealed that the synergistic interaction between modulated the electrostatic potential strength and gradient of the material,which was more favorable for the adsorption of CO_(2) molecules with small diameters and large quadrupole moment.In addition,the Ni0.11/Mg0.89-MOF-74 showed commendable cyclic stability,underscoring its promising potential for practical applications. 展开更多
关键词 CO_(2)capture Mg-MOF-74 CO_(2)/N_(2)separation adsorption breakthrough curve density functional theory
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Gradient Estimate of Solutions to a Class of Mean Curvature Equations with Prescribed Contact Angle Boundary Problem
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作者 Yuan Shengtong Han Fei 《数学理论与应用》 2024年第3期94-105,共12页
This paper studies the prescribed contact angle boundary value problem of a certain type of mean curvature equation.Applying the maximum principle and the moving frame method and based on the location of the maximum p... This paper studies the prescribed contact angle boundary value problem of a certain type of mean curvature equation.Applying the maximum principle and the moving frame method and based on the location of the maximum point,the boundary gradient estimation of the solutions to the equation is obtained. 展开更多
关键词 Moving frame Maximum principle Prescribed contact angle boundary value problem Mean curvature equation
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Three-point bending behavior of aluminum foam sandwich with steel panel 被引量:7
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作者 祖国胤 卢日环 +4 位作者 李小兵 仲照阳 马幸江 韩明博 姚广春 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2013年第9期2491-2495,共5页
Static three-point bending tests of aluminum foam sandwiches with glued steel panel were performed. The deformation and failure of sandwich structure with different thicknesses of panel and foam core were investigated... Static three-point bending tests of aluminum foam sandwiches with glued steel panel were performed. The deformation and failure of sandwich structure with different thicknesses of panel and foam core were investigated. The results indicate that the maximum bending load increases with the thickness of both steel panel and foam core. The failure of sandwich can be ascribed to the crush and shear damage of foam core and the delamination of glued interface at a large bending load, The crack on the foam wall developed in the melting foam procedure is the major factor for the failure of foam core. The sandwich structure with thick foam core and thin steel panel has the optimal specific bending strength. The maximum bending load of that with 8 mm panel and 50 mm foam core is 66.06 kN. 展开更多
关键词 aluminum foam sandwich three-point bending failure mode panel thickness
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APPROXIMATION OF INTERVAL BEZIER SURFACES
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作者 黄林 侯剑 赖俊峰 《Transactions of Nanjing University of Aeronautics and Astronautics》 EI 2011年第2期211-217,共7页
Based on the conception of perturbation, an approach to the interval Bezier surfaces approximating ra- tional surfaces is presented using the energy minimization method. The method places more restrictions on the pert... Based on the conception of perturbation, an approach to the interval Bezier surfaces approximating ra- tional surfaces is presented using the energy minimization method. The method places more restrictions on the perturbation surfaces than the original surfaces. The applications of the approach are also presented. Experimen- tal result is combined with the subdivision method to obtain a piecewise interval polynomial approximation for a rational surface. 展开更多
关键词 approximation theory rational surface interval Bezier surfacer perturbation
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Computing B-Spline Surfaces on Transputer Networks
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作者 王健 《Journal of Southeast University(English Edition)》 EI CAS 1998年第2期78-80,共3页
This paper presents a parallel implementation of computing uniform bicubic B spline surfaces on Transputer networks. The work is essential for building Transputer based CAD and graphics systems.
关键词 B spline CURVES parallel processing SURFACES TRANSPUTER
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BUCKLING ANALYSIS OF WOVEN FABRIC UNDER SIMPLE SHEAR IN WARP DIRECTION 被引量:2
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作者 张义同 徐家福 《Transactions of Tianjin University》 EI CAS 2001年第1期36-39,共4页
Buckling of a woven fabric is analyzed in this paper when it is subjected to a simple shear in warp direction.The equation to determine the buckling direction (buckling wave direction) is obtained and it is found that... Buckling of a woven fabric is analyzed in this paper when it is subjected to a simple shear in warp direction.The equation to determine the buckling direction (buckling wave direction) is obtained and it is found that the buckling direction is related to the critical amount of shear.It is shown that the out-of-plane buckling of fabric is possible and only a flexural buckling mode can exist.The buckling condition for flexural mode is obtained and the curve for that is illustrated. 展开更多
关键词 fabric mechanics fabric buckling fabric constitutive theory
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Effect of crystal orientation on tensile mechanical properties of single-crystal tungsten nanowire 被引量:4
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作者 马彬 饶秋华 贺跃辉 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2014年第9期2904-2910,共7页
Based on the high-purity single-crystal tungsten nanowire firstly prepared by the metal-catalyzed vapor-phase reaction method, molecular dynamics method was used to calculate tensile stress-strain curves and simulate ... Based on the high-purity single-crystal tungsten nanowire firstly prepared by the metal-catalyzed vapor-phase reaction method, molecular dynamics method was used to calculate tensile stress-strain curves and simulate microscopic deformation structures of the single-crystal tungsten nanowires with different crystal orientations of 〈100〉, 〈110〉and 〈111〉, in order to reveal the effect of crystal orientation on their tensile mechanical properties and failure mechanisms. Research results show that all of the stress-strain curves are classified into four stages: elastic stage, damage stage, yielding stage and failure stage, where 〈100〉orientation has a special hardening stage after yielding and two descending stages. The crystal orientation has little effect on elastic modulus but great effect on tensile strength, yielding strength and ductility, depending on different atomic surface energies and principal sliding planes. The calculated values of elastic modulus are in good agreement with the tested values of elastic modulus. 展开更多
关键词 crystal orientation stress-strain curve failure mechanism molecular dynamics single-crystal tungsten nanowire
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STUDY ON THE METHOD OF CONSTRUCTING RATIONAL CUBIC CURVES AND CURVED SURFACE INCLUDING CONTROLLING PARAMETERS
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作者 孙兰凤 高天真 +1 位作者 梁艳书 陈健 《Transactions of Tianjin University》 EI CAS 1998年第1期31-36,共6页
By adopting the method of controlling parameters this paper describes the construction of various kinds of cubic curve segment and curved surface fragment with rational and non rational parameters, and discusses the ... By adopting the method of controlling parameters this paper describes the construction of various kinds of cubic curve segment and curved surface fragment with rational and non rational parameters, and discusses the relationship between controlling parameters, weighted factors and types, kinds and characteristics of curve segments and curved surface fragments. A mathematical method is provided for CAGD with abundant connotations, broad covering region, convenience, flexibility and direct simplicity. 展开更多
关键词 controlling parameter weighted factor rational and non rational curve segment curved surface fragment matrix of parametric coefficient
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Correlation between the Change in the Number of Apis mellifera Worker Bees and Nectar Secretion of Nectariferous Plants
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作者 余玉生 张祖芸 +2 位作者 宋文菲 卢焕仙 王艳辉 《Agricultural Science & Technology》 CAS 2014年第1期116-118,136,共4页
[Objective] This study aimed to clarify the correlation between changes of Apis mel ifera and the nectar secretion characteristics of nectariferous plants. [Method] Considering the nectar secretion characteristics of ... [Objective] This study aimed to clarify the correlation between changes of Apis mel ifera and the nectar secretion characteristics of nectariferous plants. [Method] Considering the nectar secretion characteristics of major and auxiliary nec-tariferous plants, six Apis mel ifera colonies were selected for measure the number of eggs, larvae, pupae and adult bees from Jan. to Dec. in 2012; based on that, their annual change curves were also plotted. [Result] The results showed that there were three peaks of the total number of A. mel ifera workers throughout the year:the first occurred on May 15th, with bees developed into an ideal population for col-lecting pomegranate nectar, and the second and third peaks occurred on July 15th and Oct. 15th, respectively, with bees developed into an ideal population for col ect-ing E. ciliate (Thuab) Hyland. [Conclusion] Prevention of Varroa jacobsoni should be carried out with two or more types of acaricides at the late nectar flow stages of the two nectariferous plants(pomegranate and E. ciliate (Thuab) Hyland) when there was a nectar deficiency. Prevention of Tropilaelaps clareae should be timely per-formed with sublimed sulfur in conjunction with acaricides. This study provides a theoretical basis for the high-quality and high-yielding production of honey, as wel as for the product safety. 展开更多
关键词 Apis mellifera Number of worker bees Nectariferous plants CURVE Theoretical basis
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STUDIES ON POLYURETHANE FOAM POLISHING TOOL
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作者 朱纪军 左敦稳 +2 位作者 王珉 万建国 吴健 《Transactions of Nanjing University of Aeronautics and Astronautics》 EI 1996年第2期86+81-85,共6页
This paper deals with Polyurethane Foam Polishing Tool (PFPT), which has three dimensional softness and are adapted to polishing sophisticated curved surfaces. The manufacturing technology, the equilibrium theory of ... This paper deals with Polyurethane Foam Polishing Tool (PFPT), which has three dimensional softness and are adapted to polishing sophisticated curved surfaces. The manufacturing technology, the equilibrium theory of matter and energy have been discussed and the PFPT is produced successfully at our laboratory. After investigating their properties, the effective factors to the behavior of the PFPT are studied. The microcosmic construction of the PFPT have been observed by sweep electron microscope(SEM) and the polishing mechanism studied. A great deal of experiments have been carried out to optimize the manufacturing parameters. 展开更多
关键词 POLYURETHANE polishing wheels curved surface polishing mechanism parameter optimization
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蒲松龄与他的“俚曲”
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作者 李清法 《大舞台》 2005年第5期19-,共1页
蒲松龄一生著作颇丰,除<聊斋志异>外,还有文四百余篇,诗九百余首,词一百余阕,杂著数种,戏三出,通俗俚曲十几种.在这些作品中,"俚曲"也是最能代表蒲松龄创作成就和特色的组成部分.
关键词 蒲松龄 下层人民 农民起义 农民运动 理曲
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Experimental study on dynamic modulus of thermosetting epoxy asphalt mixture for steel deck pavement 被引量:1
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作者 陈磊磊 钱振东 罗桑 《Journal of Southeast University(English Edition)》 EI CAS 2010年第1期112-116,共5页
In order to study the dynamic performance of the thermosetting epoxy asphalt mixture(EAM), an experimental program on the dynamic modulus E is conducted. First, E of the EAM under different temperatures and frequenc... In order to study the dynamic performance of the thermosetting epoxy asphalt mixture(EAM), an experimental program on the dynamic modulus E is conducted. First, E of the EAM under different temperatures and frequencies are tested through the simple performance test(SPT), and the effects of temperatures and frequencies on the dynamic modulus of the EAM are analyzed. Secondly, the static modulus of the EAM and the dynamic modulus of other two ordinary mixtures are tested and compared to E of the EAM. Finally the dynamic modulus master curve is constructed using the time-temperature superposition principle. The results show that the E values increase with the increase in the test frequency while on the other hand, the E values decrease with the increase in the test temperature. It also can be seen from the results that the dynamic modulus corresponding to the actual vehicle mode is significantly greater than the static modulus, and the dynamic modulus of the EAM is greater than that of SBS mixtures and the common hot mixed asphalt (HMA). The study results can provide a theoretical basis for the design and mechanical analysis of the steel deck pavement. 展开更多
关键词 dynamic modulus epoxy asphalt mixture(EAM) master curve time-temperature superposition principle
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NEW TYPE OF LINEAR ULTRASONIC MOTOR WITH TWO DEGREES OF FREEDOM USING LONGITUDINAL AND BENDING MODE 被引量:2
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作者 李志荣 刘俊标 +1 位作者 黄卫清 赵淳生 《Transactions of Nanjing University of Aeronautics and Astronautics》 EI 2004年第1期7-12,共6页
A new type of linear ultrasonic motor with two degrees of freedom (DOF) motion is presented. The concept of the new typical motor is based on the combination of a longitudinal and two bending modes. The construction a... A new type of linear ultrasonic motor with two degrees of freedom (DOF) motion is presented. The concept of the new typical motor is based on the combination of a longitudinal and two bending modes. The construction and the operational principle of motor are described, and the elliptical motion of the driving point of the actuator is proved. Meanwhile, a prototype linear motor is designed by using the finite element method (FEM) and is constructed for experiments. The vibration modes are tested with the laser doppler vibrometer (PSV-300F), and the experimental results prove that the design requirements on the mode shape of the actuator and nature frequency are satisfied. The test run of the motor indicates that the operational principle of the motor and the design results are correct, and the output properties are also tested. 展开更多
关键词 ultrasonic motor two DOF motion linear motion elliptical motion mode shape
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DESCRIPTIONS OF THE CYLINDRICAL HELIX WITH NURBS
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作者 孙克豪 乔新 《Transactions of Nanjing University of Aeronautics and Astronautics》 EI 1997年第2期190-197,共8页
The representation of a cylindrical helix by Non-Uniform Rational B-Spline (NURBS) curves is presented in this paper. A method is proposed to assess the influences produced by different ways to determine the control v... The representation of a cylindrical helix by Non-Uniform Rational B-Spline (NURBS) curves is presented in this paper. A method is proposed to assess the influences produced by different ways to determine the control ver-texes positions of helix. The error distribution cases between the helix approximated by NURBS curves and the original theoretical one are also analyzed. Meanwhile a computational method that guarantees the precision requirements is presented. 展开更多
关键词 helixes CURVES non-uniform rational B-spline (NURBS) error distribution
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Comparison among Growth, Photosynthesis and Yield in Nanjing 9108 and Its Parents during the Late Development Stage
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作者 李霞 柯希欢 +2 位作者 陈涛 张亚东 朱镇 《Agricultural Science & Technology》 CAS 2015年第9期1933-1938,共6页
A good quality, high yield, slow mature and middle season Japonica rice variety, Nanjing 9108 and its parents Guandong 194 and Wuxiangjing 14,were taken as the materials for the study. The growth and photosynthetic ch... A good quality, high yield, slow mature and middle season Japonica rice variety, Nanjing 9108 and its parents Guandong 194 and Wuxiangjing 14,were taken as the materials for the study. The growth and photosynthetic characteristics of the rice plants at the post-flowering stage were compared and the rice yield components were examined at harvest. The results showed that as compared with Wuxiangjing 14, the per plant yield of Nanjing 9108 was 7.70% higher, and much higher than that of Guandong194. The large total grain per plant and heavy grain weigh of Nanjing 9108 were the important structure basis for its yield. Further analysis o the growth indicators showed that Nanjing 9108 had a large leaf area of upper three green leaves area and a smaller leaf base angle in the third leaf from the bottom blades, which helped get a higher photosynthetic capacity in groups. On the14 thday after flowering, Nanjing 9108 had similar value of net photosynthetic rate(Pn) to that of Wuxianjing 14, but lower than that of Guandong 194. Viewing from the parameters obtained from light response of photosynthesis on the modified model of rectangular hyperbola, Pn of Nanjing 9108 was more aptated to be saturated by light intensity and sensitive to photoinhibition. On the whole, Nanjing 9108 with high yield mainly resulted from its good plant type, grain structure and higher photosynthetic capacity in groups. Further improving its photosynthetic capacity o single leaf in Nanjing 9108 would be an important way for its super high yield po tential in the future. 展开更多
关键词 Japonica rice(Oryza sativa L.) Plant type Photosynthetic characteristics Photosynthetic light response curve YIELD
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Fuzzy Words Distribution in Management Science Research Articles 被引量:1
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作者 董艳云 白永权 蒋跃 《Sino-US English Teaching》 2007年第3期37-42,共6页
By using ZHANG Qiao's method for identifying fuzzy words (1998), the present paper makes a statistic analysis of fuzzy words appearing in about 43,000 words of 6 academic research articles in management science. A ... By using ZHANG Qiao's method for identifying fuzzy words (1998), the present paper makes a statistic analysis of fuzzy words appearing in about 43,000 words of 6 academic research articles in management science. A distribution curve of fuzzy words in management research articles is drawn in accordance with the structures of the articles, and it is proved to be reasonable for tile discourse function of each section. Furthermore, the fuzzy words are divided into three categories and eleven sub-categories, including Category Ⅰ-fuzzy words, Category Ⅱ-fuzzy words+non-fuzzy part / non-fuzzy part+fuzzy words, Category Ⅲ-approximators+fuzzy words. Distribution of fuzzy words varies in different sections of research articles in management science, because of different communicative purposes or discourse functions. Introduction section and Conclusion section have a higher occurrence rate of fuzzy words than Abstract section and Methodology and Data section. 展开更多
关键词 academic research articles in management science fuzzy words distribution curve discourse function category research
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Rational offset approximation of rational Bézier curves 被引量:2
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作者 CHENG Min WANG Guo-jin 《Journal of Zhejiang University-Science A(Applied Physics & Engineering)》 SCIE EI CAS CSCD 2006年第9期1561-1565,共5页
The problem of parametric speed approximation of a rational curve is raised in this paper. Offset curves are widely used in various applications. As for the reason that in most cases the offset curves do not preserve ... The problem of parametric speed approximation of a rational curve is raised in this paper. Offset curves are widely used in various applications. As for the reason that in most cases the offset curves do not preserve the same polynomial or rational polynomial representations, it arouses difficulty in applications. Thus approximation methods have been introduced to solve this problem. In this paper, it has been pointed out that the crux of offset curve approximation lies in the approximation of parametric speed. Based on the Jacobi polynomial approximation theory with endpoints interpolation, an algebraic rational approximation algorithm of offset curve, which preserves the direction of normal, is presented. 展开更多
关键词 Rational Bézier curve Parametric speed OFFSET Rational approximation
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Study on Real-time Look-ahead and Adaptive Parametric Curve Interpolator 被引量:2
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作者 郭伟 杜道山 +1 位作者 徐荣珍 李从心 《Journal of Shanghai Jiaotong university(Science)》 EI 2007年第3期388-393,共6页
The principle of real-time look-ahead was introduced and analysed. An adaptive parametric curve interpolator with a real-time look-ahead function was developed for non-uniform rational B-spline (NURBS) curves interpol... The principle of real-time look-ahead was introduced and analysed. An adaptive parametric curve interpolator with a real-time look-ahead function was developed for non-uniform rational B-spline (NURBS) curves interpolation, which considering the maximum acceleration/deceleration of the machine tool. In order to deal with the acceleration/deceleration around the feedrate sensitive corners, the look-ahead function was designed and illustrated. It can detect and adjust the feedrate adaptively. With the help of real-time look-ahead, the acceleration/deceleration can be limited to the range of the machine tool capacity. Thus, feedrate fluctuation is reduced. A NURBS curve interpolation experiment was provided to verify the feasibility and advantages of the proposed interpolator with a real-time look-ahead function. 展开更多
关键词 adaptive interpolator LOOK-AHEAD non-uniform rational B-spline curves feedrate sensitive corner chord error
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Improvement of the termination criterion for subdivision of the rational Bézier curves 被引量:2
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作者 章仁江 王国瑾 《Journal of Zhejiang University Science》 EI CSCD 2003年第1期47-52,共6页
By using some elementary inequalities, authors in this paper makes further improvement for estimating the heights of Bézier curve and rational Bézier curve. And the termination criterion for subdivision of t... By using some elementary inequalities, authors in this paper makes further improvement for estimating the heights of Bézier curve and rational Bézier curve. And the termination criterion for subdivision of the rational Bézier curve is also improved. The conclusion of the extreme value problem is thus further confirmed. 展开更多
关键词 Rational Bézier curves SUBDIVISION Termination criterion.
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