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Rapid alloying of CoCrFeMnNi high-entropy alloy from elemental feedstock toward high-throughput synthesis

《机械工程前沿（英文）》 2023年 第18卷 第1期 doi: 10.1007/s11465-022-0727-x

摘要： High-entropy alloys (HEAs) are considered alternatives to traditional structural materials because of their superior mechanical, physical, and chemical properties. However, alloy composition combinations are too numerous to explore. Finding a rapid synthesis method to accelerate the development of HEA bulks is imperative. Existing in situ synthesis methods based on additive manufacturing are insufficient for efficiently controlling the uniformity and accuracy of components. In this work, laser powder bed fusion (L-PBF) is adopted for the in situ synthesis of equiatomic CoCrFeMnNi HEA from elemental powder mixtures. High composition accuracy is achieved in parallel with ensuring internal density. The L-PBF-based process parameters are optimized; and two different methods, namely, a multi-melting process and homogenization heat treatment, are adopted to address the problem of incompletely melted Cr particles in the single-melted samples. X-ray diffraction indicates that HEA microstructure can be obtained from elemental powders via L-PBF. In the triple-melted samples, a strong crystallographic texture can be observed through electron backscatter diffraction, with a maximum polar density of 9.92 and a high ultimate tensile strength (UTS) of (735.3 ± 14.1) MPa. The homogenization heat-treated samples appear more like coarse equiaxed grains, with a UTS of (650.8 ± 16.1) MPa and an elongation of (40.2% ± 1.3%). Cellular substructures are also observed in the triple-melted samples, but not in the homogenization heat-treated samples. The differences in mechanical properties primarily originate from the changes in strengthening mechanism. The even and flat fractographic morphologies of the homogenization heat-treated samples represent a more uniform internal microstructure that is different from the complex morphologies of the triple-melted samples. Relative to the multi-melted samples, the homogenization heat-treated samples exhibit better processability, with a smaller composition deviation, i.e., ≤ 0.32 at.%. The two methods presented in this study are expected to have considerable potential for developing HEAs with high composition accuracy and composition flexibility.

关键词： laser powder bed fusion (L-PBF)     in situ alloying     high-entropy alloys     heat treatment     rapid synthesis    

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Urban watershed management under rapid urbanization

Pengfei DU, Haifeng JIA, Shaw L. YU

《环境科学与工程前沿（英文）》 2012年 第6卷 第5期   页码 595-595 doi: 10.1007/s11783-012-0452-5

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Development of New Modality Municipal Public Transportation for Guangzhou—Group Rapid Transit System

Ru-jiang Zhao,Wung Hee Moh

《工程管理前沿（英文）》 2015年 第2卷 第4期   页码 378-390 doi: 10.15302/J-FEM-2015061

摘要： As one of the primary business centers of China, Guangzhou has been undergoing rapid growth and expansion. Over the past decade, the Guangzhou Municipality Government has significantly upgraded its transport infrastructure, especially with the highly beneficial expansion of its Subway Mass Rapid Transit (MRT) system. Positive steps have also been taken to continue planning the construction of new roads, a Bus Rapid Transit (BRT) system and other transportation facilities. Further administrative and regulatory measures have also been implemented to control the situation, such as the banning of motorcycles from the central city area and the limitation of new automobile registrations. However, Guangzhou continues to face serious challenges of traffic congestion in and around the city center owing to further intensification of its population with economic growth. The need to ease Guangzhou’s stretched public transportation resources, and at the same time to support the realization of its “Eastward Advance” strategy, presents a unique challenge and opportunity to develop an advanced high-efficiency public transportation modality for Guangzhou, viz. the Group Rapid Transit (GRT) involving the use of automation-guided (driverless) smart-vehicles. This paper outlines the PRT/GRT (PRT: Personal Rapid Transit) smart-vehicle modality and also puts forth a proposal of Guangzhou’s first GRT route as the city’s first dedicated transportation link to the scenic landscape of the Eastern Tourism Zone. This GRT route will help in diffusing the city’s traffic congestion as well as support the effectuation of Guangzhou’s “Eastern Expansion” strategy, supplementing the ongoing expansion of the Guangzhou Municipality’s subway MRT networks.

关键词： public transportation system     innovative city transportation     Subway Mass Rapid Transit (MRT)     Bus Rapid Transit (BRT)     Group Rapid Transit (GRT)     Personal Rapid Transit (PRT)    

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Error compensation for tool-tip trace during cutting of laminated paper for rapid prototyping

Yucheng DING, Changhe LI, Dichen LI, Guoxin YU

《机械工程前沿（英文）》 2009年 第4卷 第2期   页码 111-119 doi: 10.1007/s11465-009-0020-2

摘要： Laminated object manufacturing (LOM) is one of the commercialized rapid prototyping (RP) processes, where a focused laser is usually used to cut the cross-section contours of a 3 D part and the grid hatchings of the part-exterior region on a sheet paper stack-wise. Using a laser beam as a cutter can be costly, and the thermal burning of a sheet paper along a laser scanning path can also cause an environment-polluting smoke. This paper presents a paper laminating RP system using a knife as the paper cutter instead of a laser beam. The knife holder is mounted through a radial bearing on the - positioning mechanism in such a way that the knife tip is eccentric to the bearing axis by a small distance (so-called offset). Therefore, the knife tip, which engages into the sheet paper during cutting, tends to follow the path of the -driven bearing axis by the error that depends on the path tangential and the eccentricity of the knife tip. A tractrix model is applied to describe the kinetic motion of the knife tip and a method is formulated to compensate for the tracing error of the eccentric knife tip by modifying the original cross-section contours of the part for each layer based on the tractrix equation. A study has also been performed regarding the effect of the knife tip geometry on the cutting notch of the sheet paper and on the roughness of the finished part.

关键词： rapid prototyping     laminated object manufacturing     knife-cutting     tracing error    

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Total stress rapid drawdown analysis of the Pilarcitos Dam failure using the finite element method

Daniel R. VANDENBERGE

《结构与土木工程前沿（英文）》 2014年 第8卷 第2期   页码 115-123 doi: 10.1007/s11709-014-0249-7

摘要： Rapid drawdown is a critical design condition for the upstream or riverside slope of earth dams and levees. A new total stress rapid drawdown method based on finite element analysis is used to analyze the rapid drawdown failure that occurred at Pilarcitos Dam in 1969. Effective consolidation stresses in the slope prior to drawdown are determined using linear elastic finite element analysis. Undrained strengths from isotropically consolidated undrained (ICU) triaxial compression tests are related directly to the calculated consolidation stresses and assigned to the elements in the model by interpolation. Two different interpretations of the undrained strength envelope are examined. Strength reduction finite element analyses are used to evaluate stability of the dam. Back analysis suggests that undrained strengths from ICU tests must be reduced by 30% for use with this rapid drawdown method. The failure mechanism predicted for Pilarcitos Dam is sensitive to the relationship between undrained strength and consolidation stress.

关键词： rapid drawdown     finite element     total stress     slope stability    

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Experimental study and field application of calcium sulfoaluminate cement for rapid repair of concrete

Yanhua GUAN, Ying GAO, Renjuan SUN, Moon C. WON, Zhi GE

《结构与土木工程前沿（英文）》 2017年 第11卷 第3期   页码 338-345 doi: 10.1007/s11709-017-0411-0

摘要： The fast-track repair of deteriorated concrete pavement requires materials that can be placed, cured, and opened to the traffic in a short period. Type III cement and Calcium Sulfoaluminate (CSA) cement are the most commonly used fast-setting hydraulic cement (FSHC). In this study, the properties of Type III and CSA cement concrete, including compressive strength, coefficient of thermal expansion (CTE) and shrinkage were evaluated. The test results indicate that compressive strength of FSHC concrete increased rapidly at the early age. CSA cement concrete had higher early-age and long term strength. The shrinkage of CSA cement concrete was lower than that of Type III cement concrete. Both CSA and Type III cement concrete had similar CTE values. Based on the laboratory results, the CSA cement was selected as the partial-depth rapid repair material for a distressed continuously reinforced concrete pavement. The data collected during and after the repair show that the CSA cement concrete had good short-term and long-term performances and, therefore, was suitable for the rapid repair of concrete pavement.

关键词： Calcium Sulfoaluminate (CSA) cement     Type III cement     coefficient of thermal expansion (CTE)     shrinkage     rapid repair    

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Design and characteristics of electric supercharger for diesel engine acceleration by additional rapid

YAO Chun-de, ZHOU Hong-xiu

《机械工程前沿（英文）》 2006年 第1卷 第4期   页码 409-412 doi: 10.1007/s11465-006-0048-5

摘要： The ES (electric supercharger) driven by a high-speed brushless motor was developed to solve the problem of smoke caused by the turbocharger s sluggish response during acceleration. Its rotation speed was from 6 000 r/min to 24 000 r/min, and the maximum flux was 0.1 kg/s. The structural design of the electric supercharger is novel, which makes it easier to set the lubricating installation and to assemble. The velocity distribution at the outlet of the electric supercharger is determined by hot-wire anemometry under various rotation speeds in steady state. Furthermore, the trends of the flux and charge rate with various speeds were analyzed. In addition, the transient response was detected from the motor setup to smooth running within 10 s, 15 s, 20 s and 25 s respectively, and the characteristic of the transient flux is under pilot study. Research results indicate that the electric supercharger can respond rapidly with the great flux, and it is independent of the operating conditions of a diesel engine. Therefore, it is a feasible way to reduce smoke emission and improve the acceleration performance.

关键词： acceleration     velocity distribution     high-speed brushless     turbocharger     electric supercharger    

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Application of rapid thermal processing on SiN thin film to solar cells

LI Youjie, LUO Peiqing, ZHOU Zhibin, CUI Rongqiang, HUANG Jianhua, WANG Jingxiao

《能源前沿（英文）》 2008年 第2卷 第4期   页码 519-523 doi: 10.1007/s11708-008-0095-1

摘要： Rapid thermal processing (RTP) of SiN thin films from PECVD with low temperature was investigated. A special processing condition of this technique which could greatly increase the minority lifetime was found in the experiments. The processing mechanism and the application of the technique to silicon solar cells fabrication were discussed. A main achievement is an increase of the minority lifetime in silicon wafer with SiN thin film by about 200% after the RTP was reached. PC-1D simulation results exhibit an enhancement of the efficiency of the solar cell by 0.42% coming from the minority lifetime improvement. The same experiment was also conducted with P-diffusion silicon wafers, but the increment of minority lifetime is just about 55%. It could be expected to improve the solar cell efficiency if it would be used in silicon solar cells fabrication with the combination of laser firing contact technique.
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A study on rapid acid chrome black (MB 7) spectrophotometric determination of ClO

Jing DONG, Huilong WANG

《化学科学与工程前沿（英文）》 2011年 第5卷 第2期   页码 245-251 doi: 10.1007/s11705-010-1003-x

摘要： Experiments were conducted to investigate the degradation of 2,6-dinitro- -cresol (DNPC) in the chlorine dioxide (ClO ) catalytic oxidation process. Pure aluminum oxide was used as the catalyst in this process. The degradation of DNPC by ClO using aluminum oxide as catalyst was systematically studied by varying the experimental parameters, such as pH values, catalyst dosage, the initial concentration of DNPC and ClO , reaction time, etc. Under optimal condition (DNPC concentration 39 mg·L , ClO concentration 0.234 g·L , reaction time 15 min, catalyst dosage 4.7 g·L and pH 4.32), almost complete degradation of DNPC can be achieved. The kinetic studies revealed that the ClO catalytic oxidation degradation of DNPC followed pseudo-first-order kinetics with respect to both ClO and DNPC concentration. The repetitive use of the catalyst was investigated along sequential feed-batch trials. The catalyst performed efficiently after five runs. In addition, a simple and convenient method for the determination of ClO in water was developed by using acid chrome black 7 (MB 7) spectrophotometry in this paper.

关键词： chlorine dioxide     2     6-dinitro-p-cresol (DNPC)     aluminum oxide     water treatment     MB 7 spectrophotometry    

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A microextraction approach for rapid extraction and separation of Mn(II) and Co(II) using saponified

《化学科学与工程前沿（英文）》 2022年 第16卷 第6期   页码 963-972 doi: 10.1007/s11705-021-2081-7

摘要： In this paper, we proposed a microextraction approach for the extraction and separation of Mn(II) and Co(II) from sulfate solution simulating leachate of spent lithium-ion battery cathode materials using saponified di-(2-ethylhexyl)phosphoric acid system. The effects of the following operational variables were investigated: equilibrium pH, tri-n-butyl phosphate concentration, saponification rate, two-phase ratio and residence time. The results showcased that the microextractor can reach the extraction equilibrium within 20 s, thereby greatly reducing necessary extraction time comparing to that of conventional processes. The volumetric mass transfer coefficient showed 8–21 times larger than that of batch device. With the help of microextractor, 95% of Mn(II) was extracted with a single theoretical stage at a chosen two-phase ratio of 3:1, and the separation factor βMn/Co was as large as 65.5. In the subsequent stripping step, more than 99% of manganese from loaded phase was easily stripped under optimal conditions. The microextraction approach greatly enhances the mass transfer while enabling a continuous and controllable extraction process within a simple structure design. When extracting spent electrode material with microextractors, the comprehensive recovery of mangenese can reach 96%. The microextraction approach has a good applicability in the spent lithium-ion battery cathode materials recycling at both bench and industrial scales.

关键词： extraction equilibrium     mass transfer coefficient     microextraction     multicomponent extraction     di-(2-ethylhexyl)phosphoric acid    

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A novel flavonol-based colorimetric and turn-on fluorescent probe for rapid determination of hydrazine

《化学科学与工程前沿（英文）》 2023年 第17卷 第1期   页码 24-33 doi: 10.1007/s11705-022-2171-1

摘要： Hydrazine is extremely toxic and causes severe harm to human body. Herein, a novel fluorescent probe 4-oxo-2-styryl-4H-chromen-3-yl thiophene-2-carboxylate (FHT) was synthesized for detecting hydrazine by using natural cinnamaldehyde as starting material. This probe exhibited significantly enhanced fluorescence response towards hydrazine over various common metal ions, anions, and amine compounds. The detection limit of probe FHT for hydrazine was as low as 0.14 μmol·L–1, significantly lower than that of the threshold value of 0.312 μmol·L–1, imposed by the Environmental Protection Agency. Moreover, the proposed probe was able to detect hydrazine within wide pH (5–10) and linear detection ranges (0–110 μmol·L–1). This probe was employed for determining trace hydrazine in different environmental water samples. The probe FHT-loaded filter paper strips were able to conveniently detect hydrazine of low concentration through distinct naked-eye and fluorescent color changes. Importantly, the probe FHT with low cytotoxicity was successfully applied to visualize hydrazine in living Hela cells and zebrafish.

关键词： cinnamaldehyde     3-hydroxychromone derivative     hydrazine     fluorescent probe    

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Linking key intervention timings to rapid declining effective reproduction number to quantify lessons

Zhihang Peng, Wenyu Song, Zhongxing Ding, Quanquan Guan, Xu Yang, Qiaoqiao Xu, Xu Wang, Yankai Xia

《医学前沿（英文）》 2020年 第14卷 第5期   页码 623-629 doi: 10.1007/s11684-020-0788-3

摘要： Coronavirus disease 2019 (COVID-19) is currently under a global pandemic trend. The efficiency of containment measures and epidemic tendency of typical countries should be assessed. In this study, the efficiency of prevention and control measures in China, Italy, Iran, South Korea, and Japan was assessed, and the COVID-19 epidemic tendency among these countries was compared. Results showed that the effective reproduction number( ) in Wuhan, China increased almost exponentially, reaching a maximum of 3.98 before a lockdown and rapidly decreased to below 1 due to containment and mitigation strategies of the Chinese government. The in Italy declined at a slower pace than that in China after the implementation of prevention and control measures. The in Iran showed a certain decline after the establishment of a national epidemic control command, and an evident stationary phase occurred because the best window period for the prevention and control of the epidemic was missed. The epidemic in Japan and South Korea reoccurred several times with the fluctuating greatly. The epidemic has hardly rebounded in China due to the implementation of prevention and control strategies and the effective enforcement of policies. Other countries suffering from the epidemic could learn from the Chinese experience in containing COVID-19.

关键词： COVID-19     epidemic control comparison     Chinese experience    

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An integrated method for the rapid dewatering and solidification/stabilization of dredged contaminated

Hefu Pu, Aamir Khan Mastoi, Xunlong Chen, Dingbao Song, Jinwei Qiu, Peng Yang

《环境科学与工程前沿（英文）》 2021年 第15卷 第4期 doi: 10.1007/s11783-020-1359-1

摘要： Abstract • An integrated method, called PHDVPSS, was proposed for treating DCS. • The PHDVPSS method showed superior performance compared to conventional method. • Using the method, water content (%) of DCS decreased from 300 to<150 in 3 days. • The 56-day UCS from this method is 12‒17 times higher than conventional method. • Relative to PC, GGBS-MgO binder yielded greater reduction in the leachability. To more efficiently treat the dredged contaminated sediment (DCS) with a high water content, this study proposes an integrated method (called PHDVPSS) that uses the solidifying/stabilizing (S/S) agents and prefabricated horizontal drain (PHD) assisted by vacuum pressure (VP). Using this method, dewatering and solidification/stabilization can be carried out simultaneously such that the treatment time can be significantly shortened and the treatment efficacy can be significantly improved. A series of model tests was conducted to investigate the effectiveness of the proposed method. Experimental results indicated that the proposed PHDVPSS method showed superior performance compared to the conventional S/S method that uses Portland cement (PC) directly without prior dewatering. The 56-day unconfined compressive strength of DCS treated by the proposed method with GGBS-MgO as the binder is 12‒17 times higher than that by the conventional S/S method. DCS treated by the PHDVPSS method exhibited continuous decrease in leaching concentration of Zn with increasing curing age. The reduction of Zn leachability is more obvious when using GGBS-MgO as the binder than when using PC, because GGBS-MgO increased the residual fraction and decreased the acid soluble fraction of Zn. The microstructure analysis reveals the formation of hydrotalcite in GGBS-MgO binder, which resulted in higher mechanical strength and higher Zn stabilization efficiency.

关键词： Dredged contaminated sediment     Dewatering     Solidification/stabilization     Vacuum preloading     Prefabricated horizontal drain     Heavy metal    

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Automated synthesis of steady-state continuous processes using reinforcement learning

《化学科学与工程前沿（英文）》 2022年 第16卷 第2期   页码 288-302 doi: 10.1007/s11705-021-2055-9

摘要： Automated flowsheet synthesis is an important field in computer-aided process engineering. The present work demonstrates how reinforcement learning can be used for automated flowsheet synthesis without any heuristics or prior knowledge of conceptual design. The environment consists of a steady-state flowsheet simulator that contains all physical knowledge. An agent is trained to take discrete actions and sequentially build up flowsheets that solve a given process problem. A novel method named SynGameZero is developed to ensure good exploration schemes in the complex problem. Therein, flowsheet synthesis is modelled as a game of two competing players. The agent plays this game against itself during training and consists of an artificial neural network and a tree search for forward planning. The method is applied successfully to a reaction-distillation process in a quaternary system.

关键词： automated process synthesis     flowsheet synthesis     artificial intelligence     machine learning     reinforcement learning    

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科技创造卓越——飞速发展的长沙矿冶研究院

《中国工程科学》 2001年 第3卷 第8期   页码 93-94

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标题 作者 时间 类型 操作

Rapid alloying of CoCrFeMnNi high-entropy alloy from elemental feedstock toward high-throughput synthesis

期刊论文

Urban watershed management under rapid urbanization

Pengfei DU, Haifeng JIA, Shaw L. YU

期刊论文

Development of New Modality Municipal Public Transportation for Guangzhou—Group Rapid Transit System

Ru-jiang Zhao,Wung Hee Moh

期刊论文

Error compensation for tool-tip trace during cutting of laminated paper for rapid prototyping

Yucheng DING, Changhe LI, Dichen LI, Guoxin YU

期刊论文

Total stress rapid drawdown analysis of the Pilarcitos Dam failure using the finite element method

Daniel R. VANDENBERGE

期刊论文

Experimental study and field application of calcium sulfoaluminate cement for rapid repair of concrete

Yanhua GUAN, Ying GAO, Renjuan SUN, Moon C. WON, Zhi GE

期刊论文

Design and characteristics of electric supercharger for diesel engine acceleration by additional rapid

YAO Chun-de, ZHOU Hong-xiu

期刊论文

Application of rapid thermal processing on SiN thin film to solar cells

LI Youjie, LUO Peiqing, ZHOU Zhibin, CUI Rongqiang, HUANG Jianhua, WANG Jingxiao

期刊论文

A study on rapid acid chrome black (MB 7) spectrophotometric determination of ClO

Jing DONG, Huilong WANG

期刊论文

A microextraction approach for rapid extraction and separation of Mn(II) and Co(II) using saponified

期刊论文

A novel flavonol-based colorimetric and turn-on fluorescent probe for rapid determination of hydrazine

期刊论文

Linking key intervention timings to rapid declining effective reproduction number to quantify lessons

Zhihang Peng, Wenyu Song, Zhongxing Ding, Quanquan Guan, Xu Yang, Qiaoqiao Xu, Xu Wang, Yankai Xia

期刊论文

An integrated method for the rapid dewatering and solidification/stabilization of dredged contaminated

Hefu Pu, Aamir Khan Mastoi, Xunlong Chen, Dingbao Song, Jinwei Qiu, Peng Yang

期刊论文

Automated synthesis of steady-state continuous processes using reinforcement learning

期刊论文

科技创造卓越——飞速发展的长沙矿冶研究院

期刊论文