Search | Engineering

订阅投稿

首页工程期刊工程焦点工程成就工程前沿关于我们 English

资源类型

期刊论文 117

会议视频 2

年份

2023 6

2022 7

2021 10

2020 7

2019 8

2018 3

2017 4

2016 12

2015 5

2014 9

2013 5

2012 5

2011 3

2010 3

2009 6

2008 4

2007 5

2006 5

2005 1

2004 2

展开︾

关键词

循环经济 5

秦巴山脉 3

绿色循环发展 3

S-N曲线 2

战略 2

绿色循环 2

ADV 1

F-N图 1

K型钢管混凝土节点 1

PIV 1

P波 1

QRS-T复合波 1

S—N曲线 1

U251细胞 1

V形坑 1

circRNA 1

“城市矿山” 1

互相关 1

交换机 1

展开︾

检索范围：

排序：展示方式：

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

HTML PDF 收藏

Scaled boundary finite element method with exact defining curves for two-dimensional linear multi-field

Jaroon RUNGAMORNRAT, Chung Nguyen VAN

《结构与土木工程前沿（英文）》 2019年第13卷第1期页码 201-214 doi: 10.1007/s11709-018-0488-0

摘要： This paper presents an efficient and accurate numerical technique based upon the scaled boundary finite element method for the analysis of two-dimensional, linear, second-order, boundary value problems with a domain completely described by a circular defining curve. The scaled boundary finite element formulation is established in a general framework allowing single-field and multi-field problems, bounded and unbounded bodies, distributed body source, and general boundary conditions to be treated in a unified fashion. The conventional polar coordinates together with a properly selected scaling center are utilized to achieve the exact description of the circular defining curve, exact geometry of the domain, and exact spatial differential operators. Standard finite element shape functions are employed in the discretization of both trial and test functions in the circumferential direction and the resulting eigenproblem is solved by a selected efficient algorithm. The computational performance of the implemented procedure is then fully investigated for various scenarios to demonstrate the accuracy in comparison with standard linear elements.

关键词： multi-field problems defining curve exact geometry general boundary conditions SBFEM

HTML PDF 收藏

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

HTML PDF 收藏

LEVERAGING LIVESTOCK TO PROMOTE A CIRCULAR FOOD SYSTEM

Zhengxia DOU

《农业科学与工程前沿（英文）》 2021年第8卷第1期页码 188-192 doi: 10.15302/J-FASE-2020370

摘要： Livestock provide multifaceted services to human societies worldwide. In developing countries, they are crucial assets and safety net for rural poor, and they provide nutrients-dense food to nourish people. In developed economies, growth in demand for animal-derived food is slowing while attention is growing over the role of livestock farming in an enhanced circular food system for sustainability. This analysis, focusing on the modern food systems in developed countries, aims to highlight the unique function of livestock that helps people re-harvest and upcycle crop and food residues generated along the food chain that are otherwise unfit for human consumption. First, human-unusable crop and food residue materials are described in three broad categories based on their characteristics and potential feeding attributes; the magnitude of biomass materials that are already used in routine animal feeding as well as residues that remain as underutilized resources are illustrated using the USA as an example. Then, the research and technology development critically needed for the future is discussed. As the world strives to produce more food with smaller environmental and climate footprints, upcycling the residual biomass via livestock for food production presents a viable pathway toward improved resource use, reduced pollution and enhanced food system efficiency.

HTML PDF 收藏

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

HTML PDF 收藏

LEVERAGING LIVESTOCK TO PROMOTE A CIRCULAR FOOD SYSTEM

《农业科学与工程前沿（英文）》 2021年第8卷第1期

摘要：

Livestock provide multifaceted services to human societies worldwide. In developing countries, they are crucial assets and safety net for rural poor, and they provide nutrients-dense food to nourish people. In developed economies, growth in demand for animal-derived food is slowing while attention is growing over the role of livestock farming in an enhanced circular food system for sustainability. This analysis, focusing on the modern food systems in developed countries, aims to highlight the unique function of livestock that helps people re-harvest and upcycle crop and food residues generated along the food chain that are otherwise unfit for human consumption. First, human-unusable crop and food residue materials are described in three broad categories based on their characteristics and potential feeding attributes; the magnitude of biomass materials that are already used in routine animal feeding as well as residues that remain as underutilized resources are illustrated using the USA as an example. Then, the research and technology development critically needed for the future is discussed. As the world strives to produce more food with smaller environmental and climate footprints, upcycling the residual biomass via livestock for food production presents a viable pathway toward improved resource use, reduced pollution and enhanced food system efficiency.

HTML PDF 收藏

循环经济：理念与创新

金涌,冯之浚,陈定江

《中国工程科学》 2010年第12卷第1期页码 4-11

摘要：

我国从开始关注循环经济理念,到今天把循环经济定为国家发展的基本国策之一,已经历了十余个年头。从理论探索到工程实践，在多学科共同交叉研究中，许多专家学者提出了诸多基本理念。为了承上启下，笔者试图对这方面的创新思想进行总括，作为进一步以工程科技创新推进循环经济发展的指导思想。

关键词：循环经济循环经济学

HTML PDF 收藏

Frequencies of circular plate with concentric ring and elastic edge support

null

《机械工程前沿（英文）》 2014年第9卷第2期页码 168-176 doi: 10.1007/s11465-014-0299-5

摘要：

Exact solutions for the flexural vibrations of circular plates having elastic edge conditions along with rigid concentric ring support have been presented in this paper. Values of frequency parameter for the considered circular plate are computed for different sets of values of elastic rotational and translation restraints and the radius of internal rigid ring support. The results for the first three modes of plate vibrations are computed and are presented in tabular form. The effects of rotational and linear restraints and the radius of the rigid ring support on the vibration behavior of circular plates are studied over a wide range of non-dimensional parametric values. The values of the exact frequency parameter presented in this paper for varying values of restraint parameters and the radius of the rigid ring support can better serve in design and as benchmark solutions to validate the numerical methods obtained by using other methods of solution.

关键词： circular plate frequency elastic edge rigid ring mode switching

HTML PDF 收藏

Numerical analysis of hydrodynamic process of circular-translational-moving polishing (CTMP)

ZHAI Wenjie, LIU Changxiong, LIANG Yingchun

《机械工程前沿（英文）》 2008年第3卷第4期页码 441-448 doi: 10.1007/s11465-008-0074-6

摘要： By keeping a pad moving relative to a wafer along a circular path without rotation, we developed a polishing technique called circular-translational-moving polishing (CTMP), which permits multidirectional polishing of the work piece and thus bears the advantage of isotropic polishing and a potential increase of material removal rate (MRR) on the wafer. To illuminate the mechanisms of CTMP and determine the optimum process variables in a CTMP process, a three-dimensional hydrodynamic lubrication model for CTMP with a smooth and rigid pad under a quasi-stable state is established in a polar coordinate system. The model equations are further calculated numerically by the finite difference method. The instantaneous distribution of fluid pressure is obtained, which shows that a negative pressure exists. The reason for negative pressure in CTMP and its effect on polishing is discussed. Moreover, the nominal clearance of the fluid film, roll, and pitch angles under different working conditions are obtained in terms of the applied load, moments, and polishing velocity. The obtained numerical analysis can be used as guidance for choosing operation parameters in a practical CTMP application.

关键词： numerical analysis practical CTMP circular-translational-moving polishing CTMP different

HTML PDF 收藏

A new method for boring of non-circular holes

ZHANG Kai, HU De-jin

《机械工程前沿（英文）》 2006年第1卷第4期页码 456-460 doi: 10.1007/s11465-006-0058-3

摘要： A revolving electromagnetic actuation mechanism composed of an electromagnetic stator and an electromagnetic rotor has been developed for boring non-circular holes. The main component of the rotor is a flexure-hinged based flexible body. There are four pole-pair coils in the stator supplying actuation currents. The micro-displacement between the stator and rotor can be controlled by changing the currents applied in the pole-pair coils. Through linearization of the actuation force near the static action point, a linear relationship between the control current and the actuation force was established, and the synchronizing control method of the electromagnetic actuation mechanism is presented here. With two-factor analysis of the linearization error of the actuation force, the influences of control current and micro-displacement to the linearization error of the actuation force were studied. Then, the principle for designing the basic parameters of the magnetic actuation mechanism is put forward. The calibration of the mechanism indicates that the relationship between the micro-displacement of the rotor and the control current has linear characteristics in the required micro-displacement range. Simulation tests show that the turning radius of the rotor changes with the control current. The proposed mechanism can feasibly supply a controllable micro displacement to the boring bar.

关键词： electromagnetic actuation control method displacement flexible body revolving electromagnetic

HTML PDF 收藏

Fundamental buckling of circular plates with elastically restrained edges and resting on concentric rigid

Lokavarapu Bhaskara Rao, Chellapilla Kameswara Rao

《机械工程前沿（英文）》 2013年第8卷第3期页码 291-297 doi: 10.1007/s11465-013-0255-9

摘要：

This work presents the existence of buckling mode switching with respect to the radius of concentric rigid ring support. The buckling mode may not be axisymmetric as previously assumed. In general, the plate may buckle in an axisymmetric mode but when the radius of the ring support becomes small, the plate may buckle in an asymmetric mode. The optimum radius of the concentric rigid ring support for maximum buckling load is also determined. Introducing internal rigid ring support, when placed at an optimal position increases the elastic buckling load capacity by 149.39 percent. The numerical results obtained are in good agreement with the previously published data.

关键词： buckling circular plate elastically restrained edge rigid ring support mode switching

HTML PDF 收藏

Surface accuracy optimization of mechanical parts with multiple circular holes for additive manufacturing

Jinghua XU, Hongsheng SHENG, Shuyou ZHANG, Jianrong TAN, Jinlian DENG

《机械工程前沿（英文）》 2021年第16卷第1期页码 133-150 doi: 10.1007/s11465-020-0610-6

摘要： Surface accuracy directly affects the surface quality and performance of mechanical parts. Circular hole, especially spatial non-planar hole set is the typical feature and working surface of mechanical parts. Compared with traditional machining methods, additive manufacturing (AM) technology can decrease the surface accuracy errors of circular holes during fabrication. However, an accuracy error may still exist on the surface of circular holes fabricated by AM due to the influence of staircase effect. This study proposes a surface accuracy optimization approach for mechanical parts with multiple circular holes for AM based on triangular fuzzy number (TFN). First, the feature lines on the manifold mesh are extracted using the dihedral angle method and normal tensor voting to detect the circular holes. Second, the optimal AM part build orientation is determined using the genetic algorithm to optimize the surface accuracy of the circular holes by minimizing the weighted volumetric error of the part. Third, the corresponding weights of the circular holes are calculated with the TFN analytic hierarchy process in accordance with the surface accuracy requirements. Lastly, an improved adaptive slicing algorithm is utilized to reduce the entire build time while maintaining the forming surface accuracy of the circular holes using digital twins via virtual printing. The effectiveness of the proposed approach is experimentally validated using two mechanical models.

关键词： surface accuracy optimization multiple circular holes additive manufacturing (AM) part build orientation triangular fuzzy number (TFN) digital twins

HTML PDF 收藏

Carbon performance evaluation model from the perspective of circular economy—The case of Chinese thermal

Zhifang ZHOU, Jinhao LIU, Huixiang ZENG, Mengmeng XU, Shihui LI

《工程管理前沿（英文）》 2022年第9卷第2期页码 297-311 doi: 10.1007/s42524-020-0143-z

摘要： Carbon emission reduction is the only way to alleviate environmental problems, such as global warming. Effective evaluation of carbon performance can help enterprises to carry out energy saving and emission reduction activities to a certain extent and promote sustainable development. This paper constructs a carbon performance evaluation index system that includes the four dimensions of carbon resource (energy) input, cycle, output, and carbon management by incorporating the principles of circular economy and the theory of resource value circulation from the perspective of the flow trajectory of carbon-containing resources in the circulation of enterprises combined with the production characteristics of thermoelectric enterprises. Subsequently, combined with the case study, this paper discusses the scientific and practical nature of the system and provides another way of thinking for carbon performance evaluation of micro-enterprises in other industries. This paper expands the application boundary of matter–element model and supplements the literature of carbon performance, which has certain theoretical and practical significance.

关键词： circular economy carbon performance comprehensive evaluation thermal power enterprise

HTML PDF 收藏

Mathematical model and manufacture programming of loxodromic-type normal circular-arc spiral bevel gear

Zhenyun DUAN, Houjun CHEN, Zhilan JU, Jian LIU

《机械工程前沿（英文）》 2012年第7卷第3期页码 312-321 doi: 10.1007/s11465-012-0308-5

摘要：

In this paper, loxodromic-type normal circular-arc spiral bevel gear is proposed as a novel application of the circular-arc tooth profile at the gear transmission with intersecting axes. Based on the principle of molding-surface conjugation, the study develops a mathematical model for the tooth alignment curve and the computational flow at the design stage to enable the generation of the tooth surface. Machining of the tooth surface is then carried out to determine the interference-free tool path of the numerical control (NC). Moreover, a pair of loxodromic-type normal circular-arc spiral bevel gears is manufactured on computer numerical control (CNC) machine tools. The proposed theory and method are experimentally investigated, and the obtained results primarily reflect the superior performance of the proposed novel gear.

关键词： loxodrome circular-arc tooth profile Wildhaber-Novikov (W-N) gear spiral bevel gear