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A new heat transfer correlation for supercritical fluids

Yanhua YANG, Xu CHENG, Shanfang HUANG

《能源前沿（英文）》 2009年第3卷第2期页码 226-232 doi: 10.1007/s11708-009-0022-0

摘要： A new method of heat transfer prediction in supercritical fluids is presented. Emphasis is put on the simplicity of the correlation structure and its explicit coupling with physical phenomena. Assessment of qualitative behaviour of heat transfer is conducted based on existing test data and experience gathered from open literature. Based on phenomenological analysis and test data evaluation, a single dimensionless number, the acceleration number, is introduced to correct the deviation of heat transfer from its conventional behaviour, which is predicted by the Dittus-Boelter equation. The new correlation structure excludes direct dependence of heat transfer coefficient on wall surface temperature and eliminates possible numerical convergence. The uncertainty analysis of test data provides information about the sources and the levels of uncertainties of various parameters and is highly required for the selection of both the dimensionless parameters implemented into the heat transfer correlation and the test data for the development and validation of new correlations. Comparison of various heat transfer correlations with the selected test data shows that the new correlation agrees better with the test data than other correlations selected from the open literature.

关键词： super critical fluids heat transfer circular tubes prediction method

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High-efficiency inspecting method for mobile robots based on task planning for heat transfer tubes in

《机械工程前沿（英文）》 2023年第18卷第2期 doi: 10.1007/s11465-022-0741-z

摘要： Many heat transfer tubes are distributed on the tube plates of a steam generator that requires periodic inspection by robots. Existing inspection robots are usually involved in issues: Robots with manipulators need complicated installation due to their fixed base; tube mobile robots suffer from low running efficiency because of their structural restricts. Since there are thousands of tubes to be checked, task planning is essential to guarantee the precise, orderly, and efficient inspection process. Most in-service robots check the task tubes using row-by-row and column-by-column planning. This leads to unnecessary inspections, resulting in a long shutdown and affecting the regular operation of a nuclear power plant. Therefore, this paper introduces the structure and control system of a dexterous robot and proposes a task planning method. This method proceeds into three steps: task allocation, base position search, and sequence planning. To allocate the task regions, this method calculates the tool work matrix and proposes a criterion to evaluate a sub-region. And then all tasks contained in the sub-region are considered globally to search the base positions. Lastly, we apply an improved ant colony algorithm for base sequence planning and determine the inspection orders according to the planned path. We validated the optimized algorithm by conducting task planning experiments using our robot on a tube sheet. The results show that the proposed method can accomplish full task coverage with few repetitive or redundant inspections and it increases the efficiency by 33.31% compared to the traditional planning algorithms.

关键词： steam generator transfer tubes mobile robot dexterous structure task planning efficient inspection

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Theoretical study on the confine-stiffening effect and fractal cracking of square concrete filled steel tubes

《结构与土木工程前沿（英文）》 2021年第15卷第6期页码 1317-1336 doi: 10.1007/s11709-021-0763-3

摘要： Tension stress in steel-concrete composite is widely observed in engineering design. Based on an experimental program on tension performance of three square concrete-filled tubes (SCFT), the tension theory of SCFT is proposed using a mechanics-based approach. The tension stiffening effect, the confining strengthening effect and the confining stiffening effect, observed in tests of SCFTs are included in the developed tension theory model. Subsequently, simplified constitutive models of steel and concrete are proposed for the axial tension performance of SCFT. Based on the MSC.MARC software, a special fiber beam-column element is proposed to include the confining effect of SCFTs under tension and verified. The proposed analytical theory, effective formulas, and equivalent constitutive laws are extensively verified against three available tests reported in the literature on both global level (e.g., load-displacement curves) and strain level. The experimental verification proves the accuracy of the proposed theory and formulations in simulating the performance of SCFT members under tension with the capability to accurately predict the tensile strength and stiffness enhancements and realistically simulate the fractal cracking phenomenon.

关键词： square concrete filled tubes confine-stiffening confine-strengthening fractal cracking fracture

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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.

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Civil and structural engineering applications, recent trends, research and developments on pultruded fiber reinforced polymer closed sections: a review

Alfred Kofi GAND, Tak-Ming CHAN, James Toby MOTTRAM

《结构与土木工程前沿（英文）》 2013年第7卷第3期页码 227-244 doi: 10.1007/s11709-013-0216-8

摘要： The objectives of this study are to review and evaluate the developments and applications of pultruded fiber-reinforced polymer composites in civil and structural engineering and review advances in research and developments. Several case applications are reviewed. The paper presents a state-of-the-art review of fundamental research on the behavior of pultruded fiber reinforced polymer closed sections and highlights gaps in knowledge and areas of potential further research.

关键词： fibre reinforced polymer composites behaviour of FRPs tubular sections pultruded FRP tubular profiles FRP tubes in bridges applications of pultruded FRP tubes new-build with FRP tubes

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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.

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New technique of precision necking for long tubes with variable wall thickness

Yongqiang GUO, Chunguo XU, Jingtao HAN, Zhengyu WANG

《机械工程前沿（英文）》 2020年第15卷第4期页码 622-630 doi: 10.1007/s11465-019-0565-7

摘要： This study analyzed the deformation law of rear axles with variable wall thickness under bidirectional horizontal extrusion and found that necking was accompanied by upsetting deformation through theoretical calculation, numerical simulation, and experimental research. The sequence and occurrence of necking and upsetting deformations were obtained. A theory of deformation was proposed by controlling the distribution of temperature field. Effective processes to control the wall thickness of rear axle at different positions were also proposed. The ultimate limit deformation with a necking coefficient of 0.68 could be achieved using the temperature gradient coefficient. A new technology of two-step heating and two-step extrusion for a 13 t rear axle was developed, qualified test samples were obtained, and suggestions for further industrial application were put forward.

关键词： extrusion rear axle necking coefficient temperature gradient

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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

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Frequencies of circular plate with concentric ring and elastic edge support

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《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

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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

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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

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Numerical simulation on flow of ice slurry in horizontal straight tube

Shengchun LIU,Ming SONG,Ling HAO,Pengxiao WANG

《能源前沿（英文）》 2021年第15卷第1期页码 201-207 doi: 10.1007/s11708-017-0451-0

摘要： Numerical simulation on flow of ice slurry in horizontal straight tubes was conducted in this paper to improve its transportation characteristics and application. This paper determined the influence of the diameter and length of tubes, the ice packing factors (IPF) and the flow velocity of ice slurry on pressure loss by using numerical simulation, based on two-phase flow and the granular dynamic theory. Furthermore, it was found that the deviation between the simulation results and experimental data could be reduced from 20% to 5% by adjusting the viscosity which was reflected by velocity. This confirmed the reliability of the simulation model. Thus, two mathematical correlations between viscosity and flow velocity were developed eventually. It could also be concluded that future rheological model of ice slurry should be considered in three sections clarified by the flow velocity, which determined the fundamental difference from single-phase fluid.

关键词： ice slurry horizontal tubes numerical simulation pressure drop viscosity model

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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

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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

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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

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标题作者时间类型操作

A new heat transfer correlation for supercritical fluids

Yanhua YANG, Xu CHENG, Shanfang HUANG

期刊论文

High-efficiency inspecting method for mobile robots based on task planning for heat transfer tubes in

期刊论文

Theoretical study on the confine-stiffening effect and fractal cracking of square concrete filled steel tubes

期刊论文

LEVERAGING LIVESTOCK TO PROMOTE A CIRCULAR FOOD SYSTEM

Zhengxia DOU

期刊论文

Civil and structural engineering applications, recent trends, research and developments on pultruded fiber reinforced polymer closed sections: a review

Alfred Kofi GAND, Tak-Ming CHAN, James Toby MOTTRAM

期刊论文

LEVERAGING LIVESTOCK TO PROMOTE A CIRCULAR FOOD SYSTEM

期刊论文

New technique of precision necking for long tubes with variable wall thickness

Yongqiang GUO, Chunguo XU, Jingtao HAN, Zhengyu WANG

期刊论文

循环经济：理念与创新

金涌,冯之浚,陈定江

期刊论文

Frequencies of circular plate with concentric ring and elastic edge support

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