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Hierarchical fractal structure of perfect single-layer graphene

T. Zhang, K. Ding

《机械工程前沿（英文）》 2013年第8卷第4期页码 371-382 doi: 10.1007/s11465-013-0279-1

摘要：

The atomic lattice structure of perfect single-layer graphene that can actually be regarded as a kind of hierarchical fractal structure from the perspective of fractal geometry was studied for the first time. Three novel and special discoveries on hierarchical fractal structure and sets were unveiled upon examination of the regular crystal lattices of the single-layer graphene. The interior fractal-type structure was discovered to be the fifth space-filling curve from physical realm. Two efficient methods for calculating the fractal dimension of this fresh member was also provided. The outer boundary curve had a fractal dimension equal to one, and a multi-fractal structure from a naturally existing material was found for the first time. A series of strict self-similar hexagons comprised a rotating fractal set. These hexagons slewed at a constant counterclockwise angle of 19.1° when observed from one level to the next higher level. From the perspective of fractal geometry, these pioneering discoveries added three new members to the existing regular fractal structures and sets. A fundamental example of a multi-fractal structure was also presented.

关键词： hierarchical fractal structure fractal dimension the fifth space-filling curve multi-fractal structure

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A discussion of objective function representation methods in global optimization

Panos M. PARDALOS, Mahdi FATHI

《工程管理前沿（英文）》 2018年第5卷第4期页码 515-523 doi: 10.15302/J-FEM-2018044

摘要：

Non-convex optimization can be found in several smart manufacturing systems. This paper presents a short review on global optimization (GO) methods. We examine decomposition techniques and classify GO problems on the basis of objective function representation and decomposition techniques. We then explain Kolmogorov’s superposition and its application in GO. Finally, we conclude the paper by exploring the importance of objective function representation in integrated artificial intelligence, optimization, and decision support systems in smart manufacturing and Industry 4.0.

关键词： global optimization decomposition techniques multi-objective DC programming Kolmogorov’s superposition space-filling curve smart manufacturing and Industry 4.0

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高速线材吐丝机吐丝管空间曲线研究和改进

刘宏民,姚双吉,杨利坡,庞志峰,李双来,刘武斌,闫胜友,褚建东

《中国工程科学》 2006年第8卷第11期页码 80-85

摘要：

针对唐钢高线吐丝机存在的吐丝质量问题，采用三次样条拟合现场实测数据得到吐丝管曲线方程；根据吐丝管中线材的速度和受力模型，分析线材在吐丝管中的运动状态，研究吐丝管空间曲线对吐丝质量的影响，得到吐丝管空间曲率波动过大和出口速度变化过快是导致吐丝质量不好的主要原因；通过改善吐丝管空间曲线和规范煨管工艺制度，显著改善了甩尾、吐圈摆动等吐丝质量，吐丝管寿命提高了1倍。

关键词：高速吐丝机吐丝管空间曲线

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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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Premature melt solidification during mold filling and its influence on the as-cast structure

M. WU, M. AHMADEIN, A. LUDWIG

《机械工程前沿（英文）》 2018年第13卷第1期页码 53-65 doi: 10.1007/s11465-017-0437-y

摘要：

Premature melt solidification is the solidification of a melt during mold filling. In this study, a numerical model is used to analyze the influence of the pouring process on the premature solidification. The numerical model considers three phases, namely, air, melt, and equiaxed crystals. The crystals are assumed to have originated from the heterogeneous nucleation in the undercooled melt resulting from the first contact of the melt with the cold mold during pouring. The transport of the crystals by the melt flow, in accordance with the so-called “big bang” theory, is considered. The crystals are assumed globular in morphology and capable of growing according to the local constitutional undercooling. These crystals can also be remelted by mixing with the superheated melt. As the modeling results, the evolutionary trends of the number density of the crystals and the volume fraction of the solid crystals in the melt during pouring are presented. The calculated number density of the crystals and the volume fraction of the solid crystals in the melt at the end of pouring are used as the initial conditions for the subsequent solidification simulation of the evolution of the as-cast structure. A five-phase volume-average model for mixed columnar-equiaxed solidification is used for the solidification simulation. An improved agreement between the simulation and experimental results is achieved by considering the effect of premature melt solidification during mold filling. Finally, the influences of pouring parameters, namely, pouring temperature, initial mold temperature, and pouring rate, on the premature melt solidification are discussed.

关键词： premature solidification mold filling as-cast structure modeling

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中国癌症研究基金会第五次学术会议

《中国工程科学》 2000年第2卷第5期页码 94-94

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非理想条件下空分复用研究与应用 None

Ji-ying XIANG

《信息与电子工程前沿（英文）》 2018年第19卷第3期页码 357-366 doi: 10.1631/FITEE.1700827

摘要：对空分复用技术中的非理想因素进行了理论分析，并探讨了在上述非理想工程条件下空分复用的应用，给出了实测数据。对于信道条件非理想的场景，即多通道之间相关性高，条件数大，导致高层间干扰，需要通过最优化用户匹配和降维达到最优容量。对于信道测量非理想的场景，深入分析了反馈式和非反馈式的优劣，并指出即使信道不满足互易性条件，非反馈式也是优选方法。针对上述问题，进行了理论分析和外场实测。

关键词：第五代移动通讯；条件数；信道互易性；信道反馈测量模式；信道非反馈式测量模式

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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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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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Evaluation method of dam behavior during construction and reservoir filling and application to real dams

Yuji KOHGO, Akira TAKAHASHI, Tomokazu SUZUKI,

《结构与土木工程前沿（英文）》 2010年第4卷第1期页码 92-101 doi: 10.1007/s11709-010-0009-2

摘要： In this paper we analyzed a real fill-type dam, named the Minami-Aiki Dam, to verify a numerical consolidation method with an elastoplastic model for unsaturated soils. The validities were conducted by comparing the analyzed and measured values during construction and impounding. The settlements calculated showed good agreement to those observed. Though the changing patterns of the measured and calculated pore water pressures were similar, the amounts of pore water pressures induced by the self-weights of embankment and the dissipation speeds were different. The earth pressures measured at the bottom of the core zone showed good agreement with those calculated. This method is valid for estimating behavior of fill-type dams during construction and impounding.

关键词： fill dam consolidation analysis unsaturated geo-materials impounding construction

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Numerical simulation of compaction parameters for sand-filled embankment using large thickness sand filling

Wentao WANG, Chongzhi TU, Rong LUO

《结构与土木工程前沿（英文）》 2018年第12卷第4期页码 568-576 doi: 10.1007/s11709-017-0444-4

摘要： The study uses the finite element method to simulate a new technique of highway sand embankment filling in Jianghan Plain district, which can raise the thickness of sand-filled layer from 30 cm to 70 cm and can significantly shorten the construction period based on the guarantee of sand embankment construction quality. After simulating the three compacting proposals carried out on the field test, the study uses COMSOL software to research on the compacting effects of sand-filled layers in larger thicknesses by 22 ton vibratory roller alone, and then to investigate the steady compacting effect of 12 ton vibratory roller. The simulation results indicate that the sand-filled layer thickness of 70 cm is suitable for the new sand filling technique, and the sand-filled embankment project with tight construction period is suggested to choose the 12 ton vibration roller for steady compaction.

关键词： sand embankment compaction in large thickness numerical simulation small size vibratory roller steady compaction

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中国工程院化工、冶金与材料工程学部第五届学术会议

《中国工程科学》 2004年第6卷第11期页码 93-94

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Cancer and the environment: Filling knowledge gaps together

Linda S. BIRNBAUM PhD, DABT, ATS,

《医学前沿（英文）》 2010年第4卷第2期页码 131-133 doi: 10.1007/s11684-010-0044-3

摘要： When considering disease etiology, we need to view the role of the environment along the continuum from health to disease for individuals because we know that there are complex interactions between genes, their molecular expression, and environmental factors over a person’s lifetime. We clearly have huge gaps in our knowledge along this continuum, and these gaps are natural opportunities for research. There are many factors to consider as we assess the relationship between environmental exposures over a lifetime. One factor is persistence of chemicals that “live” beyond their initial intended use. Another factor is the fact that “inert ingredients” are not really inert. “Low dose” is also another consideration. We need to understand the biological effect of low dose exposure and we should clearly define what they mean by low dose research. For example, are we measuring the administered dose, or the internal/circulating dose? There are new types of toxicity as well. For example, endocrine disruptors and engineered nanomaterials are significant classes of materials deserving significant research. Timing of exposure is a significant feature in characterizing toxicity. Environmental exposures can have a greater impact in early or later life-stages. Finally, mixtures of chemicals are an important consideration. Humans are always exposed to multiple chemicals. In short, we must remember that there is no such thing as “not exposed.” Everyone has been exposed to many and various environmental agents.

关键词： environment genes environmental exposure environmental agent persistence chemicals inert ingredients low dose

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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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太阳电池填充因子随日照强度变化的理论分析与计算

丁金磊,程晓舫,翟载腾,查珺,茆美琴

《中国工程科学》 2007年第9卷第6期页码 82-87

摘要：

根据太阳电池直流模型和最大功率点数学条件，推出短路电流、开路电压、最大功率点电流和电压以及填充因子随日照强度变化的数学关系式；并选取２个电池分别计算出在不同日照强度下上述电池参数随日照强度的变化率。验证了短路电流和最大功率点电流是近似跟日照强度成正比，开路电压和最大功率点电压是近似跟日照强度的自然对数成正比。并提出了填充因子随日照强度的变化关系不具有简单的函数形式，而对不同的太阳电池其变化关系也迥异。最后用Multisim的模拟结果检验了理论分析计算的正确性。

关键词：太阳电池日照强度输出特性填充因子