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Berlin Green Framework‑Based Gas Sensor for Room‑Temperature and High‑Selectivity Detection of Ammonia

Nano-Micro Letters 2021年第4期13卷 146-158页

作者： Tingqiang Yang Lingfeng Gao Wenxuan Wang Jianlong Kang Guanghui Zhao Delong Li Wen Chen Han Zhang Institute of Microscale Optoelectronics Collaborative Innovation Centre for Optoelectronic Science and TechnologyKey Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong ProvinceCollege of Physics and Optoelectronic EngineeringShenzhen Key Laboratory of Micro‑Nano Photonic Information TechnologyGuangdong Laboratory of Artificial Intelligence and Digital Economy(SZ)Shenzhen UniversityShenzhen 518060People’s Republic of China State Key Laboratory of Advanced Technology for Materials Synthesis and Processing School of Materials Science and EngineeringWuhan University of TechnologyWuhan 430070People’s Republic of China Research Center for Materials Genome Engineering Wuhan University of TechnologyWuhan 430070People’s Republic of China

Ammonia detection possesses great potential in atmosphere environmental protection,agriculture,industry,and rapid medical ***,it still remains a great challenge to balance the sensitivity,selectivity,working temperature,and response/recovery *** this work,Berlin green(BG)framework is demonstrated as a highly promising sensing material for ammonia detection by both density functional theory simulation and experimental gas sensing *** in BG framework offers abundant active sites for ammonia absorption,and the absorbed ammonia transfers sufficient electron to BG,arousing remarkable enhancement of *** BG framework shows remarkable response to ammonia at 50–110°C with the highest response at 80°C,which is jointly influenced by ammonia’s absorption onto BG surface and insertion into BG *** sensing performance of BG can hardly be achieved at room temperature due to its high *** of conductive Ti3CN MXene overcomes the high resistance of pure BG framework,and the simply prepared BG/Ti3CN mixture shows high selectivity to ammonia at room temperature with satisfying response/recovery speed.

关键词： Berlin green framework Gas sensor Ammonia Room temperature High selectivity

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Motion Stability Analysis of Grid-connected VSC Systems under Weak Connection Conditions

Motion Stability Analysis of Grid-connected VSC Systems unde...

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Energy, Electrical and Power engineering (CEEPE), International Conference on

作者： Yuxi Liu Feng Ji Jie Du Chang Lin Lu Gao Heming Yan School of Electric Power Engineering South China University of Technology Guangzhou China State Key Laboratory of Advanced Transmission Technology Beijing China School of Electrical Engineering Xi'an Jiaotong University Xi’an China

ISBN: (数字)9798350375794

ISBN: (纸本)9798350375800

A grid-connected voltage source converter (VSC) system may suffer from instability problem when the connection is weak. In order to ensure the safety and stability of the power grid, it is necessary to analyze the stability of grid-connected VSC system under weak connection conditions. This paper first establishes a dynamic model of grid-connected VSC system based on Lagrange dynamics, which can be numerically calculated and analyzed. Secondly, the stability of the grid-connected VSC system is analyzed by using the Lyapunov first stability criterion. Finally, the Simlink simulation is used to verify the motion stability analysis results. The results show that the method of this paper can effectively calculate the oscillation frequency of the grid-connected VSC system, and is suitable for the stability analysis when the operating point changes.

关键词： Analytical models Stability criteria Power system dynamics Dynamics Power system stability Mathematical models Numerical models

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Pre-Oxidation for Enhanced Resistance of Afa Steel to High-Temperature Molten Salt Corrosion

SSRN

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SSRN 2024年

作者： Jiang, Haocheng Yu, Haicun Gao, Yunteng Zhan, Faqi Xu, Shipeng La, Peiqing State Key Laboratory of Advanced Processing and Recycling of Non-ferrous Metals School of Materials Science and Engineering Lanzhou University of Technology Lanzhou730050 China Lanzhou University of Technology China

This study employs vacuum induction melting followed by pre-oxidation strategy to develop an alumina-forming austenitic (AFA) steel, aiming to enhance its resistance against corrosion in molten salt environments. The corrosion behavior of the steel, both before and after pre-oxidation, is investigated in a ternary carbonate molten salt at 650°C. The results reveal that pre-oxidation markedly decreases the corrosion rate from 1000.72 μm/year to 204.99 μm/year. This reduction is attributed to the formation of a protective layer composed of Al2O3 and LiAlO2 oxides. It highlights the effectiveness of pre-oxidation in improving the durability of materials against corrosive damage in high-temperature molten salt environments. © 2024, The Authors. All rights reserved.

关键词： Alumina

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Development of High Superconductor Fraction (Ba, K)Fe2as2 Wires with Improved Uniformity by Two-Axial Rolling

SSRN

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SSRN 2024年

作者： Xiong, Hao Yao, Chao Guo, Wenwen Yang, Peng Ren, Zhihong Wang, Dongliang Zhang, Xianping Ma, Yanwei Key Laboratory of Applied Superconductivity Institute of Electrical Engineering Chinese Academy of Sciences Beijing100190 China University of Chinese Academy of Sciences Beijing100049 China Institute of Electrical Engineering and Advanced Electromagnetic Drive Technology Qilu Zhongke Jinan250013 China

Iron-based superconductors are regarded as prospective candidates for high magnetic field applications since they have very high upper critical field and low anisotropy. For practical applications, it is important to develop superconducting wires with strong current carrying capability. In this work, Cu/Ag composite sheathed (Ba, K)Fe2As2 (Ba-122) iron-based superconducting wires were fabricated with a two-axial rolling deformation process and a subsequent hot isostatic pressing (HIP) heat treatment. Compared with the previously reported Cu/Ag/Ba-122 wires prepared with groove rolling, the two-axial rolling allowed to used much thinner Cu/Ag composite sheath for wire fabrication, thus greatly increasing the filling factor of superconducting materials by about 5 times to 24%, and in addition lowering the volume fraction of silver down to 16% in wires. By a comparative study on the microstructure and superconducting properties between the wires made by two-axial rolling and groove rolling processes, it is found that except for the significantly increased engineering critical current density, the former also exhibits improved homogeneity of mass distribution and uniformity of Ba-122/Ag interfaces, resulting in significantly enhanced n-values over 40 in magnetic fields up to 14 T. Our work is suggested that two-axial rolling combined with HIP processes presents a promising approach to prepare iron-based superconducting wires with high filling factor, high uniformity and low cost for practical applications. © 2024, The Authors. All rights reserved.

关键词： Hot isostatic pressing

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Investigation on microstructure and mechanical properties of Al-Zn-Mg-Cu alloys with various Zn/Mg ratios

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Journal of Materials Science & technology 2021年第26期85卷 106-117页

作者： Yan Zou Xiaodong Wu Songbai Tang Qianqian Zhu Hui Song Mingxing Guo Lingfei Cao International Joint Laboratory for Light Alloys(Ministry of Education) College of Materials Science and EngineeringChongqing UniversityChongqing400044China State Key Laboratory for Advanced Metals and Materials University of Science and TechnologyBeijing100083China Shenyang National Laboratory for Materials Science Chongqing UniversityChongqing400044China

The effects of Zn/Mg ratios on microstructure and mechanical properties of Al-Zn-Mg-Cu alloys aged at 150℃have been investigated by using tensile tests,optical metallography,scanning electron microscopy,transmission electron microscopy and atom probe tomography *** increasing Zn/Mg ratios,the ageing process is significantly accelerated and the time to peak ageing is reduced.T’phase predominates in alloys of lower Zn/Mg ratios whileη’phase predominates in alloys with a Zn/Mg ratio over ***-existence of T’phase andη’phase with a large number density is beneficial to the high strength of *** precipitates together with narrow precipitate free zones cause a brittle intergranular fracture.A strength model has been established to predict the co-strengthening effect of T’phase andη’phase in Al-Zn-Mg-Cu alloys,including the factors of the grain boundary,solid solution and precipitation.

关键词： Al-Zn-Mg-Cu alloys Zn/Mg ratio Microstructure Strength model

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Pressure-assisted Silver Sintering Structure Optimization for Power Modules 5

Pressure-assisted Silver Sintering Structure Optimization fo...

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5th International Conference on Optoelectronic Science and Materials, ICOSM 2023

作者： Zhang, Hao Xing, Yulong Gao, Lilan Liu, Zheng Tan, Yansong Lu, Guoquan Tianjin Key Laboratory for Advanced Mechatronic System Design and Intelligent Control Tianjin University of Technology Tianjin300384 China National Demonstration Center or Experimental Mechanical and Electrical Engineering Education Tianjin University of Technology Tianjin300384 China Tianjin Yixunyuan New Material Technology Co. Ltd. Tianjin300380 China School of Chemical Engineering Tianjin University Tianjin300350 China School of Materials Science and Engineering Virginia Polytechnic Institute and State University BlacksburgVA24061 United States

ISBN: (纸本)9781510674547

As mobile technology evolves from 5G to 6G, the demand for third-generation semiconductors such as SiC with higher power and frequency capabilities is increasing. Silicon Carbide power modules generate significant heat during operation, requiring large-area nano-silver sintering technology to improve module performance and reliability. However, in large-area sintering processes, low exhaust efficiency of solder paste by-products and uneven sintering pressure of the nano-silver paste result in poor sintering quality of the silver layer. This study aims to improve the sintering quality of interconnected silver layers by optimizing the sintering pressure distribution and adding rubber spacers to the sintering structure. ABAQUS was used to quantitatively analyze the effects of pressure methods and gasket material, diameter, and thickness on the stress distribution in the silver layer. Finally, based on the simulation results, an optimized sintering structure was proposed to unify the pressure and reduce the stress concentration in the silver layer, and verified experimentally by sintering tests. Compared with the traditional sintering structure, the application of a 2 mm thick fluoro rubber gasket with the same surface area as the silver layer in the optimized structure reduced the porosity to 2.15% and achieved a more dense sintered silver layer. © 2024 SPIE.

关键词： Finite element method

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P-12.4: ITO-induced biexciton quenching in CdSe colloidal quantum dots

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SID Symposium Digest of Technical Papers 2024年第S1期55卷 1353-1354页

作者： Guohong Xiang Jingrui Ma Xiangwei Qu Kai Wang Hoi Sing Kwok Xiao Wei Sun Institute of Nanoscience and Applications and Department of Electrical and Electronic Engineering Southern University of Science and Technology Shenzhen China 518055 State Key Laboratory of Advanced Displays and Optoelectronics Technologies the Hong Kong University of Science and Technology Hong Kong China Key Laboratory of Energy Conversion and Storage Technologies (Southern University of Science and Technology) Ministry of Education Guangdong University Key Laboratory for Advanced Quantum Dot Displays and Lighting Guangdong-Hong Kong-Macao Joint Laboratory for Photonic-Thermal-Electrical Energy Materials and Devices and Shenzhen Key Laboratory for Advanced Quantum Dot Displays and Lighting Southern University of Science and Technology Shenzhen China 518055

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A Dead Time Compensation Method of Constant Common Mode Voltage CPS SPWM for MMC

A Dead Time Compensation Method of Constant Common Mode Volt...

引用

China Power Supply Society electromagnetic Compatibility Conference (CPEMC)

作者： Zuoxing Wang Hong Li Yanjun Li Daozhen He Zhichang Yang School of Electrical Engineering Beijing Jiaotong University Beijing China State Key Laboratory of Advanced Power Transmission Technology State Grid Smart Grid Research Institute Beijing China

ISBN: (数字)9798331509552

ISBN: (纸本)9798331509569

The modular multi-level converter (MMC) has demonstrated significant potential in high voltage direct current (HVDC) transmission and high voltage motor drive applications. Constant common mode voltage (CMV) modulations for MMC can effectively reduce the common mode (CM) electromagnetic interference (EMI) in MMC by minimizing CMV fluctuations to zero under ideal condition. However, the dead time required to protect power semiconductor devices in MMC seriously weakens the suppression effect of constant CMV modulations on CM EMI. This paper presents a method of dead time compensation with carrier phase compensation for MMC using constant CMV carrier phase shifted (CPS) sinusoidal pulse width modulation (SPWM). Phase compensation (PC) CPS SPWM is one of the constant CMV modulations for MMC. The operation principle of PC-CPS SPWM is introduced, and the mechanism of CMV fluctuations caused by dead time is analyzed. Compensation strategies for carrier phase positions and modulation signals in dead time compensation of PC-CPS SPWM are presented as DPC-CPS SPWM. The simulation results validate the proposed method, providing guidance for modulation design in MMC with low EMI requirements.

关键词： Multilevel converters Fluctuations Phase modulation Power supplies Simulation Switching frequency electromagnetic interference High-voltage techniques Pulse width modulation Power semiconductor devices

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Biocarbon with different microstructures derived from corn husks and their potassium storage properties

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Rare Metals 2021年第11期40卷 3166-3174页

作者： Meng Zhou Qing Wang Yuan Yuan Shao-Hua Luo Ya-Hui Zhang Xin Liu School of Materials Science and Engineering Northeastern UniversityShenyang 110819China State Key Laboratory of Rolling and Automation Northeastern UniversityShenyang 110819China School of Resources and Materials Northeastern University at QinhuangdaoQinhuangdao 066004China Hebei Key Laboratory of Dielectric and Electrolyte Functional Material Qinhuangdao 066004China Qinhuangdao Key Laboratory of Advanced Energy Storage and Conversion Technology Qinhuangdao 066004China

In this paper,biocarbon was prepared from corn husks as anode materials for potassium ion batteries at temperatures ranging from 700 to 1600℃.The prepared biocarbon materials have amorphous phase structure and possess larger interlayer spacing than *** biocarbon exhibits enhanced graphitic degree and decreased amounts of surface defects,while the carbonization temperature gradually *** obtained potassium ion battery electrode at 1300℃ acquired high reversible capacity up to 216.6 mAh·g^(-1) at 0.1 A·g^(-1) after 100 cycles, and retained 128.6 mAh·g^(-1) at 1 A·g^(-1) even after500 *** results indicate that the samples prepared at 1300℃ have better electrochemical performance than other samples prepared at different temperatures,which was attributed to the decisive influence of microstructure on surface-induced and intercalating potassium storage.

关键词： Biocarbon Potassium ion battery Carbonization Capacitance Electrochemical performance

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Prediction of Transformer Oil Temperature Based on Feature Selection and Deep Neural Network

Prediction of Transformer Oil Temperature Based on Feature S...

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IEEE International Conference on Software engineering and Service Sciences (ICSESS)

作者： Yongxin Chen Shiping E Zhenan Du Kanjun Zhang Gaofeng Zhang State Grid Hubei Electric Power Research Institute Wuhan Hubei China State Key Laboratory of Advanced Electromagnetic Engineering and Technology (HUST) Wuhan Hubei China State Grid Hubei Electric Power Co. Ltd Wuhan Hubei China NR Electric Co. Ltd Nanjing Jiangsu China

ISBN: (数字)9798350389166

ISBN: (纸本)9798350389173

The prediction of transformer oil temperature is a time series prediction task, which is of great significance for the maintenance of substation equipment. In the process of multivariate prediction, not all variables are strongly correlated with the prediction of the transformer oil temperature. This paper proposes a transformer oil temperature prediction method based on Feature Selection and Smooth Residual blocks, named FSSR. A two-stage feature selection method is applied to select the related features. Residual connection is applied to convolutional neural network in smooth residual blocks. Experimental study is performed on the ETTh1 and ETTh2 datasets. With different number of selected features, the best one can reduce the average MSE (mean squared error) by at least 20% than the worst one. Compared to the baseline models, FSSR has the best accuracy. Compared with LSTM (Long Short-Term Memory network), the average MSE of FSSR decreased by 27.62% on the ETTh1 dataset, and 39.34% on the ETTh2 dataset.

关键词： Temperature distribution Substations Oils Time series analysis Oil insulation Predictive models Transformers Feature extraction Convolutional neural networks Long short term memory

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