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Uncovering the evolution of tin use in the United States and its implications

《环境科学与工程前沿（英文）》 2021年第15卷第6期 doi: 10.1007/s11783-021-1406-6

摘要：

• US tin use decreases as the GDP value added by manufacturing sector increases.

关键词： Tin use GDP Curve fitting Logistic model Gompertz model

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仅用结构响应数据识别系统模态参数的方法研究

霍兵勇,易伟建

《中国工程科学》 2015年第17卷第1期页码 151-160

摘要：

随着实验模态分析方法的广泛应用和不断发展，在工程应用中，研究者希望能减少限制条件，增加分析的可靠性。本文发展一种识别系统模态参数的新方法，本方法无需知道系统的输入信息且不用建立系统模型，仅通过对测试记录的响应信号进行频谱分析即可识别系统的模态参数，依据系统中各响应点的信号，先采用离散反卷积方法从各响应点信号中分离出谐波参数作为初步的识别结果，在此基础之上，结合频域空间曲线拟合的方法修正识别结果中受频谱混叠影响而偏差较大的谐波参数，再联合这些已提取的谐波参数得到系统的模态参数。通过对实际结构测试数据的分析，证明本方法只用输出数据识别的模态参数与模态分析软件用传递函数识别的结果一致。

关键词：仅有输出响应；系统模态参数识别；空间曲线拟合；频谱混叠

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Is there an inverted U-shaped curve?Empirical analysis of the Environmental Kuznets Curve in agrochemicals

Fei LI,Suocheng DONG,Fujia LI,Libiao YANG

《环境科学与工程前沿（英文）》 2016年第10卷第2期页码 276-287 doi: 10.1007/s11783-014-0700-y

摘要： As the largest contributor to water impairment, agriculture-related pollution has attracted the attention of scientists as well as policy makers, and quantitative information is being sought to focus and advance the policy debate. This study applies the panel unit root, heterogeneous panel cointegration, and panel-based dynamic ordinary least squares to investigate the Environmental Kuznets Curve on environmental issues resulting from use of agricultural synthetic fertilizer, pesticide, and film for 31 provincial economies in mainland China from 1989 to 2009. The empirical results indicate a positive long-run co-integrated relationship between the environmental index and real GDP per capita. This relationship takes on the inverted U-shaped Environmental Kuznets Curve, and the value of the turning point is approximately 10,000–13,000, 85,000–89,000 and over 160,000 CNY, for synthetic fertilizer nitrogen indicator, fertilizer phosphorus indicator and pesticide indicator, respectively. At present, China is subject to tremendous environmental pressure and should assign more importance to special agriculture-related environmental issues.

关键词： Environmental Kuznets Curve agrochemical China

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Learning curve of totally thoracoscopic pulmonary segmentectomy

Weibing Wu, Jing Xu, Wei Wen, Yue Yu, Xinfeng Xu, Quan Zhu, Liang Chen

《医学前沿（英文）》 2018年第12卷第5期页码 586-592 doi: 10.1007/s11684-017-0566-z

摘要：

Totally thoracoscopic pulmonary segmentectomy (TTPS) is a feasible and safe technique that requires advanced thoracoscopic skills and knowledge of pulmonary anatomy. However, data describing the learning curve of TTPS have yet to be obtained. In this study, 128 patients who underwent TTPS between September 2010 and December 2013 were retrospectively analyzed to evaluate the learning curve and were divided chronologically into three phases, namely, ascending phase (A), plateau phase (B), and descending phase (C), through cumulative summation (CUSUM) for operative time (OT). Phases A, B, and C comprised 39, 33, and 56 cases, respectively. OT and blood loss decreased significantly from phases A to C (P <0.01), and the frequency of intraoperative bronchoscopy for target bronchus identification decreased gradually (A, 8/39; B, 4/33; C, 3/56; P = 0.06). No significant differences were observed in demographic factors, conversion, complications, hospital stay, and retrieved lymph nodes among the three phases. Surgical outcomes and techniques improved with experience and volume. CUSUM_OT indicated that the learning curve of TTPS should be more than 72 cases.

关键词： thoracoscopic segmentectomy learning curve CUSUM

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复杂地质曲面三维插值—逼近拟合构造方法

李明超,缪正建,刘菲,王刚

《中国工程科学》 2011年第13卷第12期页码 103-107

摘要：

针对水利水电工程多源地质数据的特点，充分考虑了地质精度要求、曲面连续性和数据存储量等多方面的均衡，提出并实现了基于NURBS(non-uniform rational B-splines，非均匀有理样条曲线）技术的复杂地质曲面插值—逼近拟合构造方法。该方法对于工程关键区域集中且均匀分布的原始数据，采用NURBS蒙皮插值方法，使曲面严格通过这些数据点；对于周边区域分布离散的数据，采用NURBS逼近拟合方法，使曲面在给定精度下充分逼近原始数据；最后对整体曲面的地质结构合理性、几何性和精度进行检查分析和调整。实例表明，该方法所构造的地质曲面能满足地质工程师的实际需要，并能为进一步的三维地质建模提供基础。

关键词：地质曲面插值—逼近拟合三维构造多源地质数据

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Numerical investigation of circle defining curve for two-dimensional problem with general boundaries

Chung Nguyen VAN

《结构与土木工程前沿（英文）》 2019年第13卷第1期页码 92-102 doi: 10.1007/s11709-018-0472-8

摘要： The scaled boundary finite element method (SBFEM) is applied to the static analysis of two dimensional elasticity problem, boundary value problems domain with the domain completely described by a circular defining curve. The scaled boundary finite element equations is formulated within a general framework integrating the influence of the distributed body force, general boundary conditions, and bounded and unbounded domain. This paper investigates the possibility of using exact geometry to form the exact description of the circular defining curve and the standard finite element shape function to approximate the defining curve. Three linear elasticity problems are presented to verify the proposed method with the analytical solution. Numerical examples show the accuracy and efficiency of the proposed method, and the performance is found to be better than using standard linear element for the approximation defining curve on the scaled boundary method.

关键词： exact geometry circular defining curve general boundaries SBFEM

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Separation mechanism for double cylinder with shrink fitting system used for ceramics conveying rollers

Wenbin LI, Hiromasa SAKAI, Shota HARADA, Yasushi TAKASE, Nao-Aki NODA

《机械工程前沿（英文）》 2011年第6卷第3期页码 277-286 doi: 10.1007/s11465-011-0234-y

摘要：

Steel conveying rollers used in hot rolling mills must be exchanged frequently at great cost because hot conveyed strips induce wear and deterioration on the surface of roller in short periods. In previous studies, new roller structure was considered which has a ceramics sleeve connected with two steel shafts at both ends by shrink fitting. Here, although the ceramics sleeve can be used for many years, the steel shafts sometimes have to be exchanged for maintenance and reconstruction under the corrosive atmosphere. Since the thermal expansion coefficient of steel is about five times larger than that of ceramics, it is necessary to investigate how to separate the shrink fitting system by heating outside of sleeve and cooling inside of the shaft. Although how to separate the real roller has been discussed in the previous study, the separation mechanism has not been clarified yet. Therefore, in this study, several types of more fundamental models are investigated to understand the separation mechanism of real roller by the application of the finite element method. The results may be useful for designs of new rollers.

关键词： contact ceramics thermal stress heating finite element method

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与地球同步：碳氮循环在保护地球宜居性中面临的挑战 Views & Comments

Robert Socolow

《工程（英文）》 2016年第2卷第1期页码 21-22 doi: 10.1016/J.ENG.2016.01.012

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Investigating peak stresses in fitting and repair patches of buried polyethylene gas pipes

Reza KHADEMI ZAHEDI, Pouyan ALIMOURI, Hooman KHADEMI ZAHEDI, Mohammad SHISHESAZ

《结构与土木工程前沿（英文）》 2020年第14卷第1期页码 147-168 doi: 10.1007/s11709-019-0587-6

摘要： Nowadays, polyethylene composes a large number of natural gas distribution pipelines installed under the ground. The focus of the present contribution is two fold. One of the objectives is to investigate the applicability of polyethylene fittings in joining polyethylene gas pipes which are electrofused onto the pipe ends and buried under the ground, by estimating stress distribution using finite element method. The second objective is to study the effectiveness of polyethylene repair patches which are used to mend the defected pipelines by performing a finite element analysis to calculate peak stress values. Buried polyethylene pipelines in the natural gas industry, can be imposed by sever loadings including the soil-structure interaction, traffic load, soil’s column weight, internal pressure, and thermal loads resulting from daily and/or seasonal temperature changes. Additionally, due to the application of pipe joints, and repair patches local stresses superimposed on the aforementioned loading effects. The pipe is assumed to be made of PE80 resin and its jointing socket, and the repair patch is PE100 material. The computational analysis of stresses and the computer simulations are performed using ANSYS commercial software. According to the results, the peak stress values take place in the middle of the fitting and at its internal surface. The maximum stress values in fitting and pipe are below the allowable stresses which shows the proper use of introduced fitting is applicable even in hot climate areas of Ahvaz, Iran. Although the buried pipe is imposed to the maximum values of stresses, the PE100 socket is more sensitive to a temperature drop. Furthermore, all four studied patch arrangements show significant reinforcing effects on the defected section of the buried PE gas pipe to transfer applied loads. Meanwhile, the defected buried medium density polyethylene gas pipe and its saddle fused patch can resist the imposed mechanical and thermal loads of 22°C temperature increase. Moreover, increasing the saddle fusion patch length to 12 inches reduces the maximum stress values in the pipe, significantly.

关键词： Ansys software polyethylene buried pipelines polyethylene joints polyethylene patches peak von Mises stress soil-pipe interaction temperature variation

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学习曲线及在工业生产运作研究中的应用综述

陈志祥

《中国工程科学》 2007年第9卷第7期页码 82-88

摘要：

学习曲线是一种通过生产者行为学习与经验积累而得到改进的生产产出的特征函数，利用学习曲线可以科学地制定成本计划，改善作业计划、劳动定额与劳力规划，质量改善等。对国际上的研究文献、学习曲线的表现形式及其特点进行分析，探讨了几个新的应用动向。

关键词：学习曲线运作管理行为研究

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Research on physical shape preserving curve reconstruction

TANG Kelun, ZHANG Xiangwei, CHENG Siyuan, XIONG Hanwei, ZHANG Hong

《机械工程前沿（英文）》 2007年第2卷第3期页码 305-309 doi: 10.1007/s11465-007-0054-2

摘要： Fusion of various data is an effective way to improve the precision and efficiency of acquiring information in reverse engineering. A method of physical shape preserving curve reconstruction is proposed to better realize the data fusion of coordinate measuring machine (CMM) and visual information. From the principle of materials mechanics, the strain energy of the curve corresponding to the distortion is advanced as the internal energy, and the elastic potential energy of the curve is established, using a few precise measured data points as the equilibrium position, to be the external energy. On the basis of the principle of variation calculus, the basic spline finite element method (B-spline FEM) is used to determine the equilibrium position of curve deformation. Numerical simulation indicates that there is an extremely good agreement between the new fitted curve and the actual curve.

关键词： information CMM Numerical simulation effective coordinate measuring

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Interpolation of a spline developable surface between a curve and two rulings

Alicia CANTÓN,Leonardo FERNÁNDEZ-JAMBRINA

《信息与电子工程前沿（英文）》 2015年第16卷第3期页码 173-190 doi: 10.1631/FITEE.14a0210

摘要： In this paper we address the problem of interpolating a spline developable patch bounded by a given spline curve and the first and the last rulings of the developable surface. To complete the boundary of the patch, a second spline curve is to be given. Up to now this interpolation problem could be solved, but without the possibility of choosing both endpoints for the rulings. We circumvent such difficulty by resorting to degree elevation of the developable surface. This is useful for solving not only this problem, but also other problems dealing with triangular developable patches.

关键词： Developable surfaces Spline surfaces Blossoms

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Principle and curve of planetary indexing cam mechanisms

LIU Ming-tao, ZHANG Ce, YANG Yu-hu

《机械工程前沿（英文）》 2006年第1卷第4期页码 475-478 doi: 10.1007/s11465-006-0063-6

摘要： A new type of planetary indexing cam mechanism called type !c is presented. The transmission principle of type !c is discussed. Based on the principle of formation of conjugate tooth contour, the equations of the cam s pitch curve are derived. The continuity and symmetry of the cam s pitch curve are also analyzed. It can be concluded that: 1) This type has no output institution so the output precision can be improved; 2) The asymmetrical two-ring structure is used to overcome dead point and its phase angle is equal to (π - 2π/n); 3) The continuous condition of the cam s pitch curve is that the average transmission ratio is -n in an intermittent motion period.

关键词： continuity planetary average transmission symmetry intermittent

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广域电磁法和拟流场法精细探测技术——以井工一矿水害探测为例 Article

何继善

《工程（英文）》 2018年第4卷第5期页码 667-675 doi: 10.1016/j.eng.2018.09.006

摘要：

井工一矿存在严重的老空区和水害。以往的单一勘探方法，如地震法、直流电法、音频大地电磁法、可控源音频大地电磁法、瞬变电磁法等，均未能探明老采空区范围和水害赋存情况。为了解决这个难题，联合采用广域电磁法和井- 地拟流场法的三位一体立体式探测技术，并利用三维反演电阻率资料精准获取富水区域和采空区的位置，确定了不同层位水的连通性，为井工一矿的安全生产提供了可靠的技术保障。结果合理、成效显著，释放了近4 km² 的可采面积。

关键词：广域电磁法拟流场法采空区富水性精细探测

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Analysis of statistical thermodynamic model for binary protein adsorption equilibria on cation exchange adsorbent

ZHOU Xiaopeng, SU Xueli, SUN Yan

《化学科学与工程前沿（英文）》 2007年第1卷第2期页码 103-112 doi: 10.1007/s11705-007-0020-x

摘要： A study of nonlinear competitive adsorption equilibria of proteins is of fundamental importance in understanding the behavior of preparative chromatographic separation. This work describes the nonlinear binary protein adsorption equilibria on ion exchangers by the statistical thermodynamic (ST) model. The single-component and binary protein adsorption isotherms of bovine hemoglobin (Hb) and bovine serum albumin (BSA) on SP Sepharose FF were determined by batch adsorption experiments in 0.05 mol/L sodium acetate buffer at three pH values (4.5, 5.0 and 5.5) and three NaCl concentrations (0.05, 0.10 and 0.15 mol/L) at pH 5.0. The ST model was found to depict the effects of pH and ionic strength on the single-component equilibria well, with model parameters depending on the pH and ionic strength. Moreover, the ST model gave acceptable fitting to the binary adsorption data with the fitted single-component model parameters, leading to the estimation of the binary ST model parameter. The effects of pH and ionic strength on the model parameters are reasonably interpreted by the electrostatic and thermodynamic theories. Results demonstrate the availability of the ST model for describing nonlinear competitive protein adsorption equilibria in the presence of two proteins.

关键词： fundamental importance single-component equilibria acceptable fitting hemoglobin chromatographic separation