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三缸曲轴曲线分模成形工艺探究 被引量:2
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作者 杨海 周杰 +2 位作者 姬金金 林磊 张月婷 《热加工工艺》 CSCD 北大核心 2013年第3期97-98,104,共3页
根据三缸曲轴的形状特点,提出一种新的成形方案为:下料—加热—制坯—预锻—终锻。应用UG软件进行了三维造型和模具设计。为了改善平衡板充填性,在制坯模相应部位设计斜坡面,并在所有模具上添加阻力墙。针对高且薄的平衡板部位,采取了... 根据三缸曲轴的形状特点,提出一种新的成形方案为:下料—加热—制坯—预锻—终锻。应用UG软件进行了三维造型和模具设计。为了改善平衡板充填性,在制坯模相应部位设计斜坡面,并在所有模具上添加阻力墙。针对高且薄的平衡板部位,采取了曲线分模的方式,合理分配其变形量。Deform数值模拟的锻件各部位充填饱满、飞边分布均匀的且无折叠缺陷。 展开更多
关键词 三缸曲轴 数值 阻力墙 曲线分模
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枝杈类壳体零件多向主动加载成形模具结构参数优化 被引量:4
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作者 于建民 张治民 +1 位作者 王子田 王强 《塑性工程学报》 CAS CSCD 北大核心 2012年第1期60-64,共5页
采用多向主动加载成形枝杈类壳体零件具有很大的优越性,但是最大的困难就是产生飞边。该文开发了一种曲面分模型式的凹模,并通过对主动加载模具的结构参数(凸体的长度、宽度以及凹模下部锥度)进行优化,分析了各自变化条件下飞边产生的... 采用多向主动加载成形枝杈类壳体零件具有很大的优越性,但是最大的困难就是产生飞边。该文开发了一种曲面分模型式的凹模,并通过对主动加载模具的结构参数(凸体的长度、宽度以及凹模下部锥度)进行优化,分析了各自变化条件下飞边产生的情况和各自变形的均匀程度。并结合模拟的充填情况得到了最优的模具结构参数和此类模具结构的设计准则,为多向主动加载,以及模锻过程中减小飞边甚至避免产生飞边提供了理论依据。 展开更多
关键词 多向主动加载 曲线分模 变形均匀程度 结构优化
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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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Isothermal extrusion speed curve design for porthole die of hollow aluminium profile based on PID algorithm and finite element simulations 被引量:1
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作者 Jie YI Zhi-wen LIU Wen-qi ZENG 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2021年第7期1939-1950,共12页
The isothermal extrusion process of hollow aluminium profile was investigated using incremental proportional-integral-derivative(PID)control algorithm and finite element simulations.The range of extrusion speed was de... The isothermal extrusion process of hollow aluminium profile was investigated using incremental proportional-integral-derivative(PID)control algorithm and finite element simulations.The range of extrusion speed was determined by considering the maximum extrusion load and production efficiency.By taking the optimal solution temperature of the secondary phase as the target temperature,the extrusion speed–stroke curve for realizing the isothermal extrusion of the aluminium profile was obtained.Results show that in the traditional constant extrusion speed process,the average temperature of the cross-section of the aluminium profile at the die exit rapidly increases and then slowly rises with the increase in ram displacement.As the extrusion speed increases,the temperature difference at the die exit of the profile along the extrusion direction increases.The exit temperature difference between the front and back ends of the extrudate along the extrusion direction obtained by adopting isothermal extrusion is about 6.9℃.Furthermore,the heat generated by plastic deformation and friction during extrusion is balanced with the heat transfer from the workpiece to the container,porthole die and external environment. 展开更多
关键词 isothermal control extrusion speed curve porthole die extrusion PID control heat balance
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Estimating van Genuchten Model Parameters of Undisturbed Soils Using an Integral Method 被引量:16
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作者 HAN Xiang-Wei SHAO Ming-An R. HORTON 《Pedosphere》 SCIE CAS CSCD 2010年第1期55-62,共8页
The van Genuchten model is the most widely used soil water retention curve (SWRC) model. Two undisturbed soils (clay and loam) were used to evaluate the accuracy of the integral method to estimate van Genuchten mo... The van Genuchten model is the most widely used soil water retention curve (SWRC) model. Two undisturbed soils (clay and loam) were used to evaluate the accuracy of the integral method to estimate van Genuchten model parameters and to determine SWRCs of undisturbed soils. SWRCs calculated by the integral method were compared with those measured by a high speed centrifuge technique. The accuracy of the calculated results was evaluated graphically, as well as by root mean square error (RMSE), normalized root mean square error (NRMSE) and Willmott's index of agreement (1). The results obtained from the integral method were quite similar to those by the centrifuge technique. The RMSEs (4.61 ×10^-5 for Eum-Orthic Anthrosol and 2.74 × 10^-4 for Los-Orthic Entisol) and NRMSEs (1.56 × 10^-4 for Eum- Orthic Anthrosol and 1.45 ×10^-3 for Los-Orthic Entisol) were relatively small. The 1 values were 0.973 and 0.943 for Eum-Orthic Anthrosol and Los-Orthic Entisol, respectively, indicating a good agreement between the integral method values and the centrifuge values. Therefore, the integral method could be used to estimate SWRCs of undisturbed clay and loam soils. 展开更多
关键词 horizontal infiltration normalized root mean square error (NRMSE) root mean square error (RMSE) water retention. Willmott's index
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Analytical Algorithms for the Blend Ratios by Fibre-bundle Tensile Curves Part Ⅱ: Calculations of the Modulus Method and the Percentage Method 被引量:1
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作者 于伟东 Ron Postle 严灏景 《Journal of Donghua University(English Edition)》 EI CAS 2004年第4期12-19,共8页
The principles for the modulus method and the percentage method are established and discussed in the part following Part Ⅰ of the series papers, in which we proposed the various algorithms of the strength method and ... The principles for the modulus method and the percentage method are established and discussed in the part following Part Ⅰ of the series papers, in which we proposed the various algorithms of the strength method and the work method. The samples of Wool/PET blended fibre bundles, the method of fibre-bundle tensile tests and the typical specific stress-extension curves from the fibre bundles with different blend ratios are the same as in Part Ⅰ. It can be found that the theoretical results estimated by the modulus and percentage methods accord with the experimental values highly though the calculations of the two methods are slightly more complex than those of the strength and work methods. Especially, using the modulus method can not only avoid the influence of the error caused by the determination of the tensile curve of no fibre breaking in stretching, Y(e), but also need not to know the tensile curves of mono-component fibre bundles in certain calculation. The latter advantage of the modulus method exists in the percentage method too, but it should adopt the improved calculation of ones. 展开更多
关键词 fibre bundle blend ratio tensile curve WOOL PET fibre modulus.
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Prediction of multi-borehole undermine coalbed gas drainage 被引量:1
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作者 ZHANG Zhi-gang 《Journal of Coal Science & Engineering(China)》 2009年第3期295-298,共4页
By analyzing the flow character of a single drainage borehole in its effectingtime and the correlative theory introduced,the reason for 'inflexion' appearance in theflow character curve of the single draining ... By analyzing the flow character of a single drainage borehole in its effectingtime and the correlative theory introduced,the reason for 'inflexion' appearance in theflow character curve of the single draining borehole in a multi-borehole was studied.Takingthe theory of permeation fluid mechanics and so on as basis,the coalbed gas flowmodel was set up,and the numerical simulation analyzer was built for undermine gasproducts.With the results from the analyzer,the gas capacity could be calculated underdifferent conditions and comparisons made with the site measurement data. 展开更多
关键词 multi-borehole undermine coalbed gas drainage capacity prediction
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Arrhenius parameters determination in non-isothermal conditions for mechanically activated Ag_2O-graphite mixture 被引量:1
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作者 Seyed Hadi SHAHCHERAGHI Gholam Reza KHAYATI 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2014年第12期3994-4003,共10页
The non-isothermal kinetics of mechanochemical reduction of Ag2O with graphite was studied by DSC and TGA with a model of fitting Malek approach and a model-free advanced isoconversional method of Vyazovkin. To evalua... The non-isothermal kinetics of mechanochemical reduction of Ag2O with graphite was studied by DSC and TGA with a model of fitting Malek approach and a model-free advanced isoconversional method of Vyazovkin. To evaluate the kinetics parameters, Ag2O–graphite mixture of as-received and milled for 2 and 4 h samples were selected. Based on the results obtained by Vyazovkin method calculation, however, the difference between the maximum and minimum values of activation energy is less than 20%-30%of the average activation energy ((99.38±2.36) kJ/mol) and thermal decomposition of mechanically activated Ag2O for 2 h is a multi-step process. Moreover, the thermal decomposition of mechanically activated Ag2O–graphite powder activated for 4 h is a single-step process (the average activation energy=(93.68±2.26) kJ/mol). The kinetics modeling shows that the complexity of thermal decomposition of as-received Ag2O–graphite mixture is higher than that of the others. While, the autocatalytic tendency of as-received Ag2O–graphite mixture is lower than that of the others. 展开更多
关键词 mechanical activation Vyazovkin method kinetic modeling Sestak-Berggren model integral master plot method silver oxide
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A fast commonly-used algorithm of P-III distribution curve and its application
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作者 任伯帜 《Journal of Chongqing University》 CAS 2003年第2期78-80,共3页
Based on theoretical analysis and studying other methods, P-III curve is transformed into an incomplete G function by means of mathematical expression transformation, thus the mathematical model of the fast commonly-u... Based on theoretical analysis and studying other methods, P-III curve is transformed into an incomplete G function by means of mathematical expression transformation, thus the mathematical model of the fast commonly-used algorithm is drawn out. Algorithm comparison and practices demonstrate that the mathematical model has an easy algorithm, agile resolution process, very good commonality, faster convergence rate and better calculation accuracy, and can be applied to other respects. 展开更多
关键词 urban drain P-III distribution curve incomplete G function mathematical model
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Research on the Solidification Mechanism Based on the Water Characteristic Curve of Solidified Dredged Sediment
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作者 L. Li Y. Qu J.P. Bao 《Journal of Environmental Science and Engineering》 2010年第11期44-50,共7页
The fractal model about water characteristics of solidified sediment was built according to the granular metric analysis curve of solidified dredged sediment, the measured value during the low-suction stage of the cur... The fractal model about water characteristics of solidified sediment was built according to the granular metric analysis curve of solidified dredged sediment, the measured value during the low-suction stage of the curing process was used for fitting parameters in the model to obtain the complete water characteristic curve of solidified dredged sediment. Then, the quantitative calculation model of capillary water, attached water, evaporated water and bound water was built by the water characteristic curve and from the view of quantitative angle, the paper analyzed the solidification mechanism of solidified dredged sediment. The result showed that: the model can realize the quantitative calculation about different tapes of water during the curing process, the evaporated water during the curing process mainly came from the capillary water, and the generated bound water during the curing reaction came from the attached water. 展开更多
关键词 Dredged sediment SOLIDIFICATION water characteristic curve fractal dimension.
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Forming condition of transient saturated zone and its distribution in residual slope under rainfall conditions 被引量:15
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作者 曾铃 卞汉兵 +1 位作者 史振宁 何忠明 《Journal of Central South University》 SCIE EI CAS CSCD 2017年第8期1866-1880,共15页
Rainfall, as one of the most significant factors triggering the residual soil slope failure, leads to not only the reduction of soil shear strength, but also the increase of soil weight and the decrease of matric suct... Rainfall, as one of the most significant factors triggering the residual soil slope failure, leads to not only the reduction of soil shear strength, but also the increase of soil weight and the decrease of matric suction as well. All these modifications in soil properties have important influence on the slope stability. The water infiltration and redistribution inside the slope are the preconditions of the slope stability under rainfall conditions. Based on the numerical simulation via finite element method, the water infiltration process under rainfall conditions was studied in the present work. The emphases are the formation, distribution and dissipation of transient saturated zone. As for the calculation parameters, the SWCC and the saturated permeability have been determined by pressure plate test and variable head test respectively. The entire process(formation, development, dissipation) of the transient saturated zone was studied in detail. The variations of volumetric water content, matric suction and hydraulic gradient inside the slope, and the eventually raise of groundwater table were characterized and discussed, too. The results show that the major cause of the formation of transient saturated zone is ascribed to the fact that the exudation velocity of rainwater on the wetting front is less than the infiltration velocity of rainfall; as a result, the water content of the soil increases. On the other hand, the formation and extension of transient saturated zone have a close relationship with rainfall intensity and duration. The results can help the geotechnical engineers for the deeper understanding of the failure of residual slope under rainfall condition. It is also suggested that the proper drainage system in the slope may be the cost-effective slope failure mitigation method. 展开更多
关键词 slope stability residual soil slope rainfall infiltration numerical simulation transient saturated zone
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Failure Analysis in Graphite Epoxy Composite Laminates
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作者 Olanrewaju Aluko 《Journal of Mechanics Engineering and Automation》 2014年第10期813-819,共7页
The present analysis was performed to obtain bearing strength for pinned joints in uni-directional graphite epoxy composite laminates using characteristic curve model. The characteristic dimensions used to determine t... The present analysis was performed to obtain bearing strength for pinned joints in uni-directional graphite epoxy composite laminates using characteristic curve model. The characteristic dimensions used to determine the characteristic curve were evaluated using a two-dimensional finite element model that was developed in ANSYS14.5 Software. Also, two-dimensional finite element stress analysis was developed to determine the stress distribution needed to evaluate the failure. Tsai-Wu failure criterion was used in the analysis with the characteristic curve to predict bearing strength. The results of the analysis showed good agreement with experimental data. 展开更多
关键词 Bearing strength COMPOSITE finite element experiment.
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ANALYSIS OF HEIGHT CURVES BY STOCHASTIC DIFFERENTIAL EQUATIONS 被引量:1
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作者 PETRAS RUPSYS EDMUNDASPETRAUSKAS 《International Journal of Biomathematics》 2012年第5期203-217,共15页
Height diameter models are classically analyzed by fixed or mixed linear and non-linear regression models. In order to possess the among-plot variability, we propose the method- ology of stochastic differential equati... Height diameter models are classically analyzed by fixed or mixed linear and non-linear regression models. In order to possess the among-plot variability, we propose the method- ology of stochastic differential equations that is derived from the standard deterministic ordinary differential equation by adding the process variability to the growth dynamic. Age-diameter varying height model was deduced using a two-dimensional stochastic Gompertz shape process. Another focus of the article is the investigation of normal cop- ula procedure, when the tree diameter and height are governed by univariate stochastic Gompertz shape processes. The advantage of the stochastic differential equation method- ology is that it analyzes a residual variability, corresponding to measurements error, and an individual variability to represent heterogeneity between subjects more complex than commonly used fixed effect models. An analysis of 900 Scots pine (Pinus sylvestris) trees provided the data for this study. 展开更多
关键词 Stochastic differential equation transition density copula.
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Predicting Soil Moisture Characteristic Curves from Continuous Particle-Size Distribution Data 被引量:16
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作者 M.H.MOHAMMADI F.MESKINI-VISHKAEE 《Pedosphere》 SCIE CAS CSCD 2013年第1期70-80,共11页
Soil moisture characteristic curve (SMC) is a fundamental soil property and its direct measurement is tedious and time consuming. Therefore, various indirect methods have been developed to predict SMC from particle-... Soil moisture characteristic curve (SMC) is a fundamental soil property and its direct measurement is tedious and time consuming. Therefore, various indirect methods have been developed to predict SMC from particle-size distribution (PSD). However, the majority of these methods often yield intermittent SMC data because they involve estimating individual SMC points. The objectives of this study were 1) to develop a procedure to predict continuous SMC from a limited number of experimental PSD data points and 2) to evaluate model predictions through comparisons with measured values. In this study, an approach that allowed predicting SMC from the knowledge of PSD, parameterized by means of the closed-form van Genuchten model (VG), was used. Through using Mohammadi and Vanclooster (MV) model, the parameters obtained from fitting of VG to PSD data were applied to predict SMC curves. Since the residual water content (Or) could not be obtained through fitting of VG-MV integrated model to PSD data, we also examined and compared four different methods estimating 0r. Results showed that the proposed equation (MV-VG integrated model) provided an excellent fit to all the PSD data and the model could adequately predict SMC as measured in forty-two soils sampled from different regions of Iran. For all soils, the method in which Or Was obtained through parameter optimization procedure provided the best overall predictions of SMC. The two methods estimating Or with Campbell and Shiozawa (CS) model resulted in less accuracy than the optimization procedure. Furthermore, the proposed model underestimated the moisture content in the dry range of SMC when the value of 0r was assumed to equal zero. 0r could be attributed to the incomplete desorption of water coated on soil particles and the accurate estimation of 0r was critical in prediction of SMC, especially for fine-textured soils at high suction heads. It could be concluded that the advantages of our approach were the continuity, robustness, and independency of model performance on soil type, allowing to improve predictions of SMC from PSD at the field and watershed scales. 展开更多
关键词 fine-textured soils modeling residual water content soil hydraulic properties van Genuchten model
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Numerical Investigation of Centerline Curvature Effects on a Compact S-shaped Intake 被引量:1
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作者 Enliang Huang Shengfeng Zhao +3 位作者 Zhijun Lei Jianxiong Kang Xingen Lu Junqiang Zhu 《Journal of Thermal Science》 SCIE EI CAS CSCD 2012年第5期413-419,共7页
Taking into account stealth, structure and maintenance, ultra-compact S-shaped intake has been widely used in modem vehicles. In this paper a series of steady numerical simulation were carried out to investigate the c... Taking into account stealth, structure and maintenance, ultra-compact S-shaped intake has been widely used in modem vehicles. In this paper a series of steady numerical simulation were carried out to investigate the complex flow mechanism in s-shaped intake, particular attention was given to examining the effect of centerline curvature on the performance and flowfield of an ultra-compact S-shaped intake. In order to validate the multi-block model, the computational results for Royal Aircraft Establishment intake 2129-M2129 which had modest centerline cur- vature distribution were corrected with available experimental test data. The numerical simulation results agreed fairly well with the experimental data, and the computational method was then used to investigate the effects of different centerline curvature distributions on performance and flow field in compact S-shaped intake. Detailed analyses of the flow visualization had exposed the different flow topologies between the cases with different cen- terline curvature. It was found that different centerline curvature distributions changed the initial location and the size of separation bubble, as well as the strength of two counter-rotating vortices at the entrance of engine. 展开更多
关键词 S-shaped Intake Secondary Flow Centerline Curvature Separation bubble Counter-rotating Vortices
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GEOMETRIC METHOD OF SEQUENTIAL ESTIMATION RELATED TO MULTINOMIAL DISTRIBUTION MODELS
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作者 WEIBOCHENG LISHOUYE 《Chinese Annals of Mathematics,Series B》 SCIE CSCD 1995年第4期487-498,共12页
In 1980's, differential geometric methods are successfully used to study curved exponential families and normal nonlinear repression models. This paper presents a new geometric structure to study multinomial distr... In 1980's, differential geometric methods are successfully used to study curved exponential families and normal nonlinear repression models. This paper presents a new geometric structure to study multinomial distributipn models which contain a set of nonlinear parameters. Based on this geometric structure, the authors study several asymptotic properties for sequential estimation. The bias, the variance and the information loss of the sequeatial estimates are given from geometric viewpoint, and a limit theorem connected with the obServed and expected Fisher information is obtained ill terms of curVature measures. The results show that the sequeotial estimation procedure has some better properties which are generally impossible for nonsequeotial estimation procedures. 展开更多
关键词 Multinomial distribution model Statistical curvature Sequential estimation Stopping rule Fisher information Information loss
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