检索结果-南通市图书馆

Microstructure and Internal Friction Behavior of Laser 3D Printed Fe-Based Amorphous Composites

在线全文

学校读者我要写书评

暂无评论

Acta Metallurgica Sinica(English Letters) 2024年第1期37卷 196-204页

作者： Shuilong huang Qingjun Chen Li ji Kan Wang Guosheng huang School of Material Science and Engineering Nanchang Hangkong UniversityNanchang330063China State Key Laboratory for Marine Corrosion and Protection Luoyang Ship Material Research Institute(LSMRI)Qingdao266237China

Laser 3D printing,also known as laser additive manufacturing(LAM),is favored for its ability to form bulk metallic glass(BMG)and its composite materials(BMGcs)with freeform geometries.In this work,two different kinds of Fe_(41)Co_(7)Cr_(15)Mo_(14)C_(15)B_(6)Y_(2)amorphous coatings(A and B)were prepared by using LAM technology under air-and water-cooled conditions,respectively;meanwhile,to reduce the cracks generated due to the residual thermal stresses,coating C obtained by air-sweep annealing of B with a low energy-density laser.The morphology and amorphous content and microstructure of the coatings were investigated,the results show many cracks in coating B deposited under water-cooled conditions,and its microstructure shows an amorphous-crystal-nanocrystalline mixed structure.Cracking was suppressed in coating C,obtained by air-sweep annealing based on coating B,but the amorphous content was reduced from 32.6 to 13.4%.And the hardness and corrosion resistance of the coating will increase with the increase in the amorphous content.Finally,the internal friction behavior of a BMGcs was prepared on the basis of the process of sample C is compared with that of as-cast amorphous alloys.The results show that the low temperature internal friction behavior of BMGcs is affected by the defects produced during printing,and the high temperature internal friction behavior is affected by the precipitated hard phase.

关键词： Laser 3D printing Amorphous coating Microstructure Corrosion resistance Internal friction behavior

Ca_(2)MnO_(4)-layered perovskite modified by NaNO_(3)for chemical-looping oxidative dehydrogenation of ethane to ethylene

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Journal of Chemical Engineering 2024年第4期68卷 53-64页

作者： Weixiao Ding kun Zhao Shican jiang Zhen huang Fang He College of Chemistry and Bioengineering Guilin University of TechnologyGuilin 541006China Guangzhou Institute of Energy Conversion Chinese Academy of SciencesGuangzhou 510640China School of Chemistry and Chemical Engineering Nanjing University of Science and TechnologyNanjing 210094China

Chemical-looping oxidative dehydrogenation(CL-ODH)is a process designed for the conversion of alkanes into olefins through cyclic redox reactions,eliminating the need for gaseous O_(2).In this work,we investigated the use of Ca_(2)MnO_(4)-layered perovskites modified with NaNO_(3)dopants,serving as redox catalysts(also known as oxygen carriers),for the CL-ODH of-thane within a temperature range of 700-780℃.Our findings revealed that the incorporation of NaNO_(3)as a modifier significantly-nhanced the selectivity for-thylene generation from Ca_(2)MnO_(4).At 750℃and a gas hourly space velocity of 1300 h^(-1),we achieved an-thane conversion up to 68.17%,accompanied by a corresponding-thylene yield of 57.39%.X-ray photoelectron spectroscopy analysis unveiled that the doping NaNO_(3)onto Ca_(2)MnO_(4)not only played a role in reducing the oxidation state of Mn ions but also increased the lattice oxygen content of the redox catalyst.Furthermore,formation of NaNO_(3)shell on the surface of Ca_(2)MnO_(4)led to a reduction in the concentration of manganese sites and modulated the oxygen-releasing behavior in a step-wise manner.This modulation contributed significantly to the-nhanced selectivity for-thylene of the NaNO_(3)-doped Ca_(2)MnO_(4)catalyst.These findings provide compelling-vidence for the potential of Ca_(2)MnO_(4)-layered perovskites as promising redox catalysts in the context of CL-ODH reactions.

关键词： Chemical-looping oxidative dehydrogenation Ethane Ethylene NaNO_(3)-doped Ca_(2)MnO_(4)redox catalyst Layered perovskites

Machine learning with active pharmaceutical ingredient/polymer interaction mechanism:Prediction for complex phase behaviors of pharmaceuticals and formulations

同方期刊数据库博看期刊评论

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Chemical Engineering 2024年第2期66卷 263-272页

作者： Kai Ge Yiping huang Yuanhui ji jiangsu Province Hi-Tech Key Laboratory for Biomedical Research School of Chemistry and Chemical EngineeringSoutheast UniversityNanjing 211189China

The high throughput prediction of the thermodynamic phase behavior of active pharmaceutical ingredients(APIs)with pharmaceutically relevant excipients remains a major scientific challenge in the screening of pharmaceutical formulations.In this work,a developed machine-learning model efficiently predicts the solubility of APIs in polymers by learning the phase equilibrium principle and using a few molecular descriptors.Under the few-shot learning framework,thermodynamic theory(perturbed-chain statistical associating fluid theory)was used for data augmentation,and computational chemistry was applied for molecular descriptors'screening.The results showed that the developed machine-learning model can predict the API-polymer phase diagram accurately,broaden the solubility data of APIs in polymers,and reproduce the relationship between API solubility and the interaction mechanisms between API and polymer successfully,which provided efficient guidance for the development of pharmaceutical formulations.

关键词： Multi-task machine learning Density functional theory Hydrogen bond interaction Miscibility Solubility

维普期刊数据库博看期刊

Non-equilibrium kinetic separation of thulium,yttrium and erbium on the surface of freely rising oil droplets

在线全文

学校读者我要写书评

暂无评论

Journal of Rare Earths 2024年第1期42卷 200-209,I0007页

作者： Na Sui Shukai Miao Kaihui Cui Fancheng Meng kun huang School of Metallurgical and Ecological Engineering University of Science and Technology BeijingBeijing100083China Beijing Key Laboratory of Green Recovery and Extraction of Rare and Precious Metals University of Science and Technology BeijingBeijing100083China Key Laboratory of Green Process and Engineering Institute of Process EngineeringChinese Academy of SciencesBeijing100190China

It is difficult to achieve selective separation and enrichment of different rare earths from high abundance yttrium ores efficiently only dependent on their discrepancy in thermodynamic properties.The present work suggests a new strategy based on non-equilibrium kinetic separation of Er and Tm on the surface of freely rising oil droplets to control the separation order of Y.It is revealed that the mutual separation of Er/Tm is significantly promoted with the separation coefficient of 2.89 during the non-equilibrium extraction with the addition of diethylenetriaminepentaacetic acid(DTPA).The extraction sequence of Tm,Er and Y can be controlled as Tm>Y>Er,thus Y can be selectively enriched during the process of separation of Er and Tm,Such a sequence is subject to the controllable dissociation rates of RE(Ⅲ)-DTPA complexes and extraction abilities of P507 with the three RE(Ⅲ)ions.The dissociation rate is dependent on the stabilities of RE(Ⅲ)-DTPA complexes and follows the sequence ofY(Ⅲ)—DTPA Er>Y to Tm>Y>Er.

关键词： DTPA Interface interaction Non-equilibrium kinetic separation Rare earths P507

Theoretical and numerical research on the dynamic launch response of carbon fiber composite cartridges

在线全文

学校读者我要写书评

暂无评论

Defence Technology（防务技术） 2024年第3期33卷 426-436页

作者： Ruijie Zhang Hui Xu Chenlei huang kun Liu Zhilin Wu School of Mechanical Engineering Nanjing University of Science and TechnologyNanjing 210094JiangsuChina

Understanding the dynamic response of composite material cartridges during the firing process is of great significance for improving their reliability and safety.A theoretical model describing the dynamic response of composite material cartridges is established based on the thick-walled cylinder theory and rate-dependent constitutive model of composite materials.The correctness of the theoretical model is validated through finite element simulations of cartridge deformation.The influence of chamber pressure and cartridge wall thickness on the cartridge's deformation process and stress distribution is analyzed.The results indicate that the primary deformation of composite material cartridges inside the chamber is elastic deformation.Compared to metal cartridges,composite material cartridges require higher pressure for touching-chamber and are more prone to developing gaps after unloading to ensure smooth extraction.During the deformation process,the touching-chamber behavior of the cartridge can improve the stress distribution.Under the same chamber pressure,the touching-chamber behavior can reduce the circumferential stress by approximately 30%.The inner wall surface of the cartridge is a critical area that requires attention.The touching-chamber behavior can be facilitated by appropriately reducing the cartridge wall thickness while ensuring overall strength.This study can provide guidance for the optimization design of composite material cartridges.

关键词： Composite material cartridges Dynamic response Thick-walled cylinder theory Finite element simulation Toughing-chamber behavior

In-situ powder mixing for laser-based directed energy deposition of functionally graded materials

在线全文

学校读者我要写书评

暂无评论

Advances in Manufacturing 2024年第1期12卷 150-166页

作者： ji-Peng Chen Shou-Chun Xie He huang School of Mechanical and Electronic Engineering Nanjing Forestry UniversityNanjing210037People’s Republic of China Nanjing Huirui Photoelectric Technology Co. LtdNanjing211121People’s Republic of China

The mixing of powders is a highly relevant field under additive manufacturing,however,it has attracted limited interest to date.The in-situ mixing of various powders remains a significant challenge.This paper proposes a new method utilizing a static mixer for the in-situ mixing of multiple powders through the laser-based directed energy deposition(DED)of functionally graded materials.Firstly,a powder-mixing experimental platform was established;WC and 316L powders were selected for the mixing experiments.Secondly,scanning electron microscopy,energy dispersive spectroscopy,and image processing were used to visually evaluate the homogeneity and proportion of the in-situ mixed powder.Furthermore,powder-mixing simulations were conducted to determine the powder-mixing mechanism.In the simulations,a powder carrier gas flow field and particle mixing were employed.Finally,a WC/316L metal matrix composite sample was produced using laser-based DED to verify the application potential of the static mixer.It was found that the static mixer could adjust the powder ratio online,and a response time of 1–2 s should be considered when adjusting the ratio of the mixed powder.A feasible approach for in-situ powder mixing for laser-based DED was demonstrated and investigated,creating the basis for functionally graded materials.

关键词： Laser Deposition Static mixer Powder mixing Functionally graded materials

Black tea markets worldwide: Are they integrated?

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Integrative Agriculture 2022年第2期21卷 552-565页

作者： XU Yong-mei QIAO Fang-bin huang ji-kun School of Economics Zhejiang Gongshang UnviersityHangzhou 310018P.R.China China Economics and Management Academy Central University of Finance and EconomicsBeijing 100081P.R.China China Center for Agricultural Policy Peking UniversityBeijing 100871P.R.China

Global tea consumption has risen significantly alongside rapid expansion of international trade in recent years.However,few studies have systematically examined the relationship among the major tea markets worldwide.Using weekly data from 2012-2019,this study empirically analyzed the price series of the world’s major black tea auction markets.The estimation results showed that these markets are connected,even though heterogeneities vary.This finding holds not only for regional markets but also for international markets.The findings offer important implications for tea-producing countries with millions of smallholder farmers.

关键词： black tea market price integration VECM

Low-resolution Kramers-Kronig detection system with error-feedback noise shaping

在线全文

学校读者我要写书评

暂无评论

Science China(Information Sciences) 2024年第5期67卷 259-269页

作者： Xiangyong DONG Zhenming YU Hongyu huang Kaixuan SUN kun XU State Key Laboratory of Information Photonics and Optical Communications Beijing University of Posts and Telecommunications

In this paper, we investigated the effects of error-feedback noise shaping(EFNS) on a lowresolution Kramers-Kronig(KK) detection system for the first time. Both 16-ary quadrature amplitude modulation(16-QAM) and 64-ary quadrature amplitude modulation(64-QAM) were considered in the experiment. The carrier tone was added on the transmitter side using the virtual carrier-assisted single sideband(VCA-SSB) method to meet the minimum phase(MP) condition. Under the MP condition, KK detection only needs the intensity of the optical signal to be detected by one photodiode(PD) to retrieve the phase information. However, the virtual carrier tone increases the carrier-to-signal power ratio(CSPR), which results in a high peak-to-average power ratio(PAPR) at the transmitter, causing an increase in quantization noise. To mitigate quantization noise in the low-resolution KK detection system, EFNS was applied. The application of EFNS increased the optimal CSPR of the KK detection system and improved receiver sensitivity. Using a 4-bit DAC and the EFNS, 80 km transmission was achieved in the 60-Gbit/s 64-QAM KK detection system.

关键词： optical fiber communications Kramers-Kronig receiver error-feedback noise shaping quantization noise carrier-to-signal power ratio

Fractal Study on the Evolution of Micro-Pores in Concrete Under Freeze-Thaw

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Journal of Wuhan University of Technology(Materials Science) 2024年第1期39卷 109-117页

作者：孙浩然邹春霞 XU Deru GUO Xiaosong huang kun College of Water Conservancy and Civil Engineering Inner Mongolia Agricultural UniversityHohhot 010018China Xi’an HaiTang Vocational College Xi’an 710038China

After exposure to freeze-thaw cycles, scanning electron microscopy(SEM) and nuclear magnetic resonance(NMR) were used to test the four mixtures. The microstructure is qualitatively analyzed from the 2D SEM image and the 3D pore distribution curve before and after freezing and thawing. The fractal dimension is utilized to characterize the two-dimensional topography image and the three-dimensional pore distribution, quantitatively. The results reveal that the surface porosity and volume porosity increase as the freeze-thaw action increases. Self-similarity characteristics exist in micro-damage inside the concrete. In the fractal dimension, it is possible to characterize pore evolution quantitatively. The fractal dimension correlates with pore damage evolution. The fractal dimension effectively quantitatively characterizes micro-damage features at various scales from the local to the global level.

关键词： fractal dimension freeze-thaw cycle concrete SEM NMR