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Advances in polishing of internal structures on parts made by laser-based powder bed fusion

《机械工程前沿（英文）》 2023年 第18卷 第1期 doi: 10.1007/s11465-022-0724-0

摘要： The internal structures of metallic products are important in realizing functional applications. Considering the manufacturing of inner structures, laser-based powder bed fusion (L-PBF) is an attractive approach because its layering principle enables the fabrication of parts with customized interior structures. However, the inferior surface quality of L-PBF components hinders its productization progress seriously. In this article, process, basic forms, and applications relevant to L-PBF internal structures are reviewed comprehensively. The causes of poor surface quality and differences in the microstructure and property of the surface features of L-PBF inner structures are presented to provide a perspective of their surface characteristics. Various polishing technologies for L-PBF components with inner structures are presented, whereas their strengths and weaknesses are summarized along with a discussion on the challenges and prospects for improving the interior surface quality of L-PBF parts.

关键词： laser-based powder bed fusion     polishing     internal structures     surface quality     surface features     post process     additive manufacturing    

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Cylindrical particulate internal flows: A review

Lizhong HUANG, Xiang GAO, Jianzhong LIN

《机械工程前沿（英文）》 2012年 第7卷 第4期   页码 385-393 doi: 10.1007/s11465-012-0354-z

摘要：

The study of cylindrical particulate internal flows has wide industrial applicability hence received much attention. This article reviews the cylindrical particulate internal flows over the past twenty years. The research is related to the cylindrical particulate flows in the straight channel, curved channel and rotational channel. Finally, several open research issues have been identified.

关键词： cylindrical particulate flow     internal flow    

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CFD Simulation of thermal hydraulic characteristics in a typical upper plenum of RPV

Mingjun WANG, Lianfa WANG, Yingjie WANG, Wenxi TIAN, Jian DENG, Guanghui SU, Suizheng QIU

《能源前沿（英文）》 2021年 第15卷 第4期   页码 930-945 doi: 10.1007/s11708-021-0728-1

摘要： A comparative computational fluid dynamics (CFD) study was conducted on the three different types of pressurized water reactor (PWR) upper plenum, named TYPE 1 (support columns (SCs) and control rod guide tubes (CRGTs) with two large windows), TYPE 2 (SCs and CRGTs without windows), and TYPE 3 (two parallel perforated barrel shells and CRGTs). First, three types of upper plenum geometry information were collected, simplified, and adopted into the BORA facility, which is a 1/5 scale system of the four-loop PWR reactor. Then, the geometry, including the upper half core, upper plenum region, and hot legs, was built using the platform. After that, an unsteady calculation to simulate the reactor balance operation at hot full power scenario was performed. Finally, the differences of flowrate distribution at the core outlet and temperature distribution and transverse velocity inside the hot legs with different upper plenum internals were compared. The results suggest that TYPE 1 upper plenum internals cause the largest flowrate difference at the core outlet while TYPE 3 leads to the most even distributed flowrate. The distribution and evolution pattern of the tangential velocity inside hot legs is highly dependent on the upper plenum internals. Two counter-rotating swirls exist inside the TYPE 1 hot leg and only one swirl revolving around the hog leg axis exist inside the TYPE 2 hot leg. For TYPE 3, two swirls like that of TYPE 1 rotating around the hot leg axis significantly increase the temperature homogenization speed. This research provides meaningful guidelines for the future optimization and design of advanced PWR upper plenum internal structures.

关键词： pressurized water reactor (PWR)     upper plenum     internal structures     temperature distribution     computational fluid dynamics (CFD)    

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Current progress on internal medicine in China—2006 Part I

YAO Dingkang, ZHU Liang, ZHAO Xue, MEI Changlin

《医学前沿（英文）》 2007年 第1卷 第3期   页码 235-247 doi: 10.1007/s11684-007-0046-y

摘要： The growing interest has been placed in the current state of Chinaºs internal medicine from all over the world. Many data of internal medicine in China were collected by searching through some of the most prominent medical magazines published in China in 2006. Because there are many researches on the field of internal medicine, just some representative reports focusing on this topic were selected in this paper. In part I of this study, a summary of the advances made in cardiology, respiration diseases, and gastroenterology was presented.

关键词： internal medicine     Chinaºs internal     respiration     gastroenterology     cardiology    

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Unified cycle model of a class of internal combustion engines and their optimum performance characteristics

Shiyan ZHENG

《能源前沿（英文）》 2011年 第5卷 第4期   页码 367-375 doi: 10.1007/s11708-011-0170-x

摘要： The unified cycle model of a class of internal combustion engines is presented, in which the influence of the multi-irreversibilities mainly resulting from the adiabatic processes, finite-time processes and heat leak loss through the cylinder wall on the performance of the cycle are taken into account. Based on the thermodynamic analysis method, the mathematical expressions of the power output and efficiency of the cycle are calculated and some important characteristic curves are given. The influence of the various design parameters such as the high-low pressure ratio, the high-low temperature ratio, the compression and expansion isentropic efficiencies etc. on the performance of the cycle is analyzed. The optimum criteria of some important parameters such as the power output, efficiency and pressure ratio are derived. The results obtained from this unified cycle model are very general and useful, from which the optimal performance of the Atkinson, Otto, Diesel, Dual and Miller heat engines and some new heat engines can be directly derived.

关键词： internal combustion engine     irreversibility     power output     efficiency     optimization    

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An Empirical Study on the Internal Control Efficiency of Listed Engineering Companies

Zhi-wen Wang,Jing Tong

《工程管理前沿（英文）》 2015年 第2卷 第2期   页码 159-164 doi: 10.15302/J-FEM-2015026

摘要： The authors carried out an empirical study on the internal control efficiency of publically listed engineering companies in China. This study presents an exploration of the relationship of independent director ratios, audit committee quality and auditor independence with the internal control efficiency of publically listed engineering companies and forward suggestions and recommendations on raising the internal control efficiency of publically listed engineering companies.

关键词： internal control efficiency     board of directors     independent directors     audit committee    

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Embankment dam foundation analysis for the decrease of internal erosion likelihood

Marc SMITH

《结构与土木工程前沿（英文）》 2012年 第6卷 第4期   页码 431-436 doi: 10.1007/s11709-012-0183-5

摘要： A zoned embankment dam is founded on clay underlain by a sand deposit. Major seepage phenomena were noticed in the foundation downstream from the dam where the vertical seepage forces in the sand layer were expected to exceed the downward forces due to the overlying clay. Modern technologies were applied to delineate critical zones to help design optimal rehabilitation measures. A global electromagnetic survey was carried out to detect and map the main sources, pathways and exits of seepage. Based on these global findings, a more detailed analysis was then conducted to identify zones where thickness of the foundation clay is minimal, pore pressures in sand are higher and thus where the factor of safety against uplift is lower and internal erosion is more likely to occur. Clay thickness evaluation required the determination of land surface as well as clay-sand contact elevations. A laser airborne survey was performed to model the land surface elevation. Data concerning the clay-sand contact elevation came from the interpreted stratigraphy based on a series of boreholes and cone penetration tests. This data was combined in a geostatistical model along with the measured piezometric levels in the foundation. This resulted in a contour map showing factors of safety against uplift over the entire downstream area. The use of modern technologies, namely electromagnetic and laser surveys as well as geostatistical tools, was instrumental in defining the limits of an otherwise spread-out problem and to provide an optimal solution, in terms of costs and effectiveness, for the long-term stabilization of the foundation.

关键词： seepage detection     geostatistical analysis     dam monitoring     internal erosion     LIDAR survey    

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investigation of the chemical and electrochemical characteristics of planar solid oxide fuel cell with direct internal

Yuzhang WANG, Shilie WENG, Yiwu WENG

《能源前沿（英文）》 2011年 第5卷 第2期   页码 195-206 doi: 10.1007/s11708-011-0148-8

摘要： A fully three-dimensional mathematical model of a planar solid oxide fuel cell (SOFC) with complete direct internal steam reforming was constructed to investigate the chemical and electrochemical characteristics of the porous-electrode-supported (PES)-SOFC developed by the Central Research Institute of Electric Power Industry of Japan. The effective kinetic models developed over the Ni/YSZ anode takes into account the heat transfer and species diffusion limitations in this porous anode. The models were used to simulate the methane steam reforming processes at the co- and counter-flow patterns. The results show that the flow patterns of gas and air have certain effects on cell performance. The cell at the counter-flow has a higher output voltage and output power density at the same operating conditions. At the counter-flow, however, a high hotspot temperature is observed in the anode with a non-fixed position, even when the air inlet flow rate is increased. This is disadvantageous to the cell. Both cell voltage and power density decrease with increased air flow rate.

关键词： planar solid oxide fuel cell (SOFC)     direct internal reforming     chemical reaction     methane     electrochemical    

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enhancement and acute biotoxicity removal through the treatment of pharmaceutical wastewater using a combined internal

Liang SUN, Can WANG, Min JI, Fen WANG

《环境科学与工程前沿（英文）》 2011年 第5卷 第3期   页码 481-487 doi: 10.1007/s11783-011-0341-3

摘要： Actual pharmaceutical wastewater was treated using a combined ultrasonic irradiation (US) and iron/coke internal electrolysis (Fe/C) technology. A significant synergetic effect was observed, showing that ultrasonic irradiation dramatically enhanced the chemical oxygen demand (COD) removal efficiencies by internal electrolysis. The effects of primary operating factors on COD removal were evaluated systematically. Higher ultrasonic frequency and lower pH values as well as longer reaction time were favorable to COD removal. The ratio of biochemical oxygen demand (BOD) and COD (B/C) of the wastewater increased from 0.21 to 0.32 after US-Fe/C treatment. An acute biotoxicity assay measuring the inhibition of bioluminescence indicated that the wastewater with overall toxicity of 4.3 mg-Zn ·L was reduced to 0.5 mg-Zn ·L after treatment. Both the raw and the treated wastewater samples were separated and identified. The types of compounds suggested that the increased biodegradability and reduced biotoxicity resulted mainly from the destruction of N,N-2 dimethyl formamide and aromatic compounds in the pharmaceutical wastewater.

关键词： internal electrolysis     ultrasonic     pharmaceutical wastewater     biodegradability     acute biotoxicity    

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Influence of temperature on cam-tappet lubrication in an internal combustion engine

CHANG Qiuying, YANG Peiran, WANG Jing, CHEN Quanshi

《机械工程前沿（英文）》 2007年 第2卷 第4期   页码 489-492 doi: 10.1007/s11465-007-0085-8

摘要： The transient thermo-elastohydrodynamic (TEHL) lubrication simulation and isothermal elastohydrodynamic (EHL) simulation were performed on the exhausting cam-tappet friction pair of an internal combustion engine. Although by employing the two models the center pressure, the thickness of the lubricant film and friction coefficient obtained were similar in the changing trend during a rotating cycle, the parameters make a great difference, especially for the thickness of the lubricant film; the TEHL was four times thicker than the EHL. These results show that the temperature should not be neglected in the study of the lubrication of cam-tappet pairs.

关键词： coefficient     combustion     isothermal elastohydrodynamic     temperature     thickness    

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Typical off-design analytical performances of internal combustion engine cogeneration

Xiaohong HE, Ruixian CAI

《能源前沿（英文）》 2009年 第3卷 第2期   页码 184-192 doi: 10.1007/s11708-009-0007-z

摘要： Based on experimental data, typical off-design characteristic curves with corresponding formulas of internal combustion engine (ICE) are summarized and investigated. In combination with analytical solution of single-pressure heat recovery steam generator (HRSG) and influence of ambient pressure on combined heat and power (CHP) system, off-design operation regularities of ICE cogeneration are analyzed. The approach temperature difference Δ , relative steam production and superheated steam temperature decrease with the decrease in engine load. The total energy efficiency, equivalent exergy efficiency and economic exergy efficiency first increase and then decrease. Therefore, there exists an optimum value, corresponding to ICE best efficiency operating condition. It is worth emphasizing that Δ is likely to be negative in low load condition with high design steam parameter and low ICE design exhaust gas temperature. Compared with single shaft gas turbine cogeneration, Δ in ICE cogeneration is more likely to be negative. The main reason for this is that the gas turbine has an increased exhaust gas flow with the decrease in load; while ICE is on the contrary. Moreover, ICE power output and efficiency decrease with the decrease in ambient pressure. Hence, approach temperature difference, relative steam production and superheated steam temperature decrease rapidly while the cogeneration efficiencies decrease slightly. It is necessary to consider the influence of ambient conditions, especially the optimization of ICE performances at different places, on cogeneration performances.

关键词： internal combustion engine (ICE)     cogeneration     heat recovery steam generator (HRSG)     off-design     superheated steam     saturated steam     ambient pressure    

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Reaction kinetics and internal diffusion of Zhundong char gasification with CO

Yun Liu, Jiangyuan Qu, Xuehui Wu, Kai Zhang, Yuan Zhang

《化学科学与工程前沿（英文）》 2021年 第15卷 第2期   页码 373-383 doi: 10.1007/s11705-020-1949-2

摘要： Mass transfer usually affects the rate of chemical reactions in coal. The effect of internal diffusion on char gasification with CO in the temperature range from 1123 K to 1273 K was investigated via thermo-gravimetric analysis and assessment of char morphology features. The results revealed that the effect of internal diffusion on the initial reaction rate was more significant with an increase of particle size, due to the concentration gradient of the gasification agent within the solid particles. In the early stage of gasification, the generation of new micropores and the opening of closed pores led to an increase in specific surface area. As the reaction proceeded, the openings were gradually expanded and the specific surface area continued to increase. However, with further reaction, disappearance of edge pores, melting and collapse of the pore structure led to a decrease in specific surface area. The intrinsic activation energy and reaction order based on the th-order model were 157.67 kJ∙mol and 0.36, respectively. Thus, temperature zones corresponding to chemical reaction and diffusion control were identified. Moreover, the calculated effectiveness factor provided a quantitative estimation of internal diffusion in the initial stage.

关键词： coal char     CO2 gasification     internal diffusion     pore evolution    

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Current progress on internal medicine in China—2006 Part II

YAO Dingkang, ZHU Liang, YU Renqian, MEI Changlin

《医学前沿（英文）》 2007年 第1卷 第4期   页码 343-351 doi: 10.1007/s11684-007-0066-7

摘要： A lot of progress has been made on internal medicine in the past year. Here a great deal of data were collected about internal medicine in China by searching for some most important medicine magazines published in China in 2006. Because there are so many articles on internal medicine, some representative reports were selected and further reviewed. In the part II, a summary of advances made in four branches includes nephrology, hematology, endocrinology and metabolism, rheumatology.

关键词： endocrinology     rheumatology     hematology     nephrology     representative    

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Numerical study of internal flow field and flow passage improvement of an inlet particle separator

Florian PAOLI, Tong WANG

《能源前沿（英文）》 2011年 第5卷 第4期   页码 386-397 doi: 10.1007/s11708-011-0156-8

摘要： By performing gas flow field numerical simulations for several inlet Reynolds numbers (from 2 × 10 to 9 × 10 ) and byflow ratios (from 10% to 20%), the present study has proposed to improve the flow passage of an inlet particle separator. An adjacent objective of the study is to lower pressure losses of the inlet particle separator (IPS). No particle has been included in the gas flow for a -epsilon turbulence model. The velocity distribution in different sections and the pressure coefficient along the duct have been analyzed, which indicates that there exist important low-velocity regions and vortices in the separation area. Therefore, the profile of streamlines along the original passage has been considered. This profile illustrated a vacuum region in the same area. All investigations suggest that the separation area is the most critical one for fulfilling the objective on pressure losses limitation. Then the flow passage improvement method has focused on the separation area. An improved shape has been designed in order to suit smoothly to the streamlines in this region. Similar numerical studies as those for the original shape have been conducted on this improved shape, confirming some considerable enhancements compared with the original shape. The significant vortices which appear in the original shape reduce in amount and size. Besides, pressure losses are greatly decreased in both outlets (up to 30% for high Reynolds number) and the flow is uniform at the main outlet. Subsequent engineering surveys could rely on expressions obtained for in both outlets which extend the pressure losses for a wide range of inlet Reynolds numbers. As a result, the numerical calculations demonstrate that the flow passage improvement method applied in this study has succeeded in designing a shape which enhances the flow behavior.

关键词： streamlines     pressure losses     flow passage improvement     inlet particle separator (IPS)    

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Application and development of modern long-span space structures in China

Shilin DONG, Yang ZHAO, Dong XING

《结构与土木工程前沿（英文）》 2012年 第6卷 第3期   页码 224-239 doi: 10.1007/s11709-012-0166-6

摘要： Modern long-span space structures, developed during the 1970s and 1980s, are light and effective structures based on new technologies and light-weight high-strength materials, such as membranes and steel cables. These structures include air-supported membrane structures, cable-membrane structures, cable truss structures, beam string structures, suspen-domes, cable domes, composite structures of cable dome and single-layer lattice shell, Tensairity structures and so forth. For the premodern space structures widely used since the mid-twentieth century (such as thin shells, space trusses, lattice shells and ordinary cable structures), new space structures have been developed by the combination of different structural forms and materials. The application of prestressing technology and the innovation of structural concepts and configurations are also associated with modern space structures, including composite space trusses, open-web grid structures, polyhedron space frame structures, partial double-layer lattice shells, cable-stayed grid structures, tree-type structures, prestressed segmental steel structures and so forth. This paper provides a review of the structural characteristics and practical applications in China of modern rigid space structures, modern flexible space structures and modern rigid-flexible combined space structures.

关键词： modern long-span space structures     rigid space structures     flexible space structures     rigid-flexible combined space structures     application and development    

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标题 作者 时间 类型 操作

Advances in polishing of internal structures on parts made by laser-based powder bed fusion

期刊论文

Cylindrical particulate internal flows: A review

Lizhong HUANG, Xiang GAO, Jianzhong LIN

期刊论文

CFD Simulation of thermal hydraulic characteristics in a typical upper plenum of RPV

Mingjun WANG, Lianfa WANG, Yingjie WANG, Wenxi TIAN, Jian DENG, Guanghui SU, Suizheng QIU

期刊论文

Current progress on internal medicine in China—2006 Part I

YAO Dingkang, ZHU Liang, ZHAO Xue, MEI Changlin

期刊论文

Unified cycle model of a class of internal combustion engines and their optimum performance characteristics

Shiyan ZHENG

期刊论文

An Empirical Study on the Internal Control Efficiency of Listed Engineering Companies

Zhi-wen Wang,Jing Tong

期刊论文

Embankment dam foundation analysis for the decrease of internal erosion likelihood

Marc SMITH

期刊论文

investigation of the chemical and electrochemical characteristics of planar solid oxide fuel cell with direct internal

Yuzhang WANG, Shilie WENG, Yiwu WENG

期刊论文

enhancement and acute biotoxicity removal through the treatment of pharmaceutical wastewater using a combined internal

Liang SUN, Can WANG, Min JI, Fen WANG

期刊论文

Influence of temperature on cam-tappet lubrication in an internal combustion engine

CHANG Qiuying, YANG Peiran, WANG Jing, CHEN Quanshi

期刊论文

Typical off-design analytical performances of internal combustion engine cogeneration

Xiaohong HE, Ruixian CAI

期刊论文

Reaction kinetics and internal diffusion of Zhundong char gasification with CO

Yun Liu, Jiangyuan Qu, Xuehui Wu, Kai Zhang, Yuan Zhang

期刊论文

Current progress on internal medicine in China—2006 Part II

YAO Dingkang, ZHU Liang, YU Renqian, MEI Changlin

期刊论文

Numerical study of internal flow field and flow passage improvement of an inlet particle separator

Florian PAOLI, Tong WANG

期刊论文

Application and development of modern long-span space structures in China

Shilin DONG, Yang ZHAO, Dong XING

期刊论文