检索结果-南通市图书馆

Cascading V_(2)O_(3)/N-doped carbon hybrid nanosheets as high-performance cathode materials for aqueous zinc-ion batteries

在线全文

学校读者我要写书评

暂无评论

Chinese Chemical Letters 2022年第3期33卷 1430-1434页

作者： Yue Niu denghui wang Yingjie Ma Linjie Zhi CAS Key Laboratory of Nanosystem and Hierarchical Fabrication CAS Center for Excellence in NanoscienceNational Center for Nanoscience and TechnologyBeijing 100190China University of Chinese Academy of Sciences Beijing 100039China

In recent years, especially when there is increasing concern about the safety issue of lithium-ion batteries (LIBs), aqueous Zn-ion batteries (ZIBs) have been getting a lot of attention because of their cost-effectiveness, materials abundance, high safety, and ecological friendliness. Their working voltage and specific capacity are mainly determined by their cathode materials. Vanadium oxides are promising cathode materials for aqueous ZIBs owing to their low cost, abundant resources, and multivalence. However, vanadium oxide cathodes still suffer from unsatisfactory capacity, poor stability, and low electrical conductivity. In this work, cascading V_(2)O_(3)/nitrogen doped carbon (V_(2)O_(3)/NC) hybrid nanosheets are prepared for high-performance aqueous ZIBs by pyrolyzing pentyl viologen dibromide (PV) intercalated V_(2)O5 nanosheets. The unique structure features of V_(2)O_(3)/NC nanosheets, including thin sheet-like morphology, small crystalline V_(2)O_(3) nanoparticles, and conductive NC layers, endow V_(2)O_(3)/NC with superior performance compared to most of the reported vanadium oxide cathode materials for aqueous ZIBs. The V_(2)O_(3)/NC cathode exhibits the discharge capacity of 405 mAh/g at 0.5 A/g, excellent rate capability (159 mAh/g at 20 A/g), and outstanding cycling stability with 90% capacity retention over 4000 cycles at 20 A/g.

关键词： Aqueous zinc ion batteries Cathode materials Vanadium oxides Nitrogen doped carbon 2D nanosheets High performance

2D Ca/Nb-based perovskite oxide with Ta doping as highly efficient H_(2)O_(2)synthesis catalyst

在线全文

学校读者我要写书评

暂无评论

Nano Research 2024年第6期17卷 4934-4942页

作者： Xingchen Yang Yang Gao Xiaohui Xu Wenqiang Xu denghui wang Bin Luo Dong Liu Tao Liang Bin wang CAS Key Laboratory of Nanosystem and Hierarchical Fabrication National Center for Nanoscience and TechnologyBeijing 100190China University of Chinese Academy of Sciences Beijing 100049China Nanomaterials Centre School of Chemical Engineering and Australian Institute for Bioengineering and Nanotechnologythe University of QueenslandSt LuciaQLD 4072Australia State Key Laboratory of Organic–Inorganic Composites College of Chemical EngineeringCollege of Materials Science and EngineeringBeijing University of Chemical TechnologyBeijing 100029China Hangzhou Institute for Advanced Study University of Chinese Academy of SciencesHangzhou 310024China State Key Lab of Silicon Materials Zhejiang UniversityHangzhou 310027China

Perovskite oxides(POs)are emerging as a class of highly efficient catalysts for reducing oxygen to H_(2)*** a rich variety of POs-based catalysts have been developed by tuning the complex composition,a highly efficient PO catalyst that is able to alter the reaction pathway from a 4e−process to a 2e−process for H_(2)O_(2)production has rarely been *** modified the structure and composition of a Ca-and Nb-based PO material by realizing a uniform two-dimensional(2D)morphology and varied Ta doping,resulting in the 2D Ca_(2)Nb_(3−x)Ta_(x)O_(10)−(x=0,0.5,1,and 1.5)monolayer *** obtained catalysts exhibit a dominant 2e−pathway and show exceptional H_(2)O_(2)production *** typical Ca_(2)Nb_(2.5)Ta_(0.5)O_(10)−nanoflakes showed an onset potential of 0.735 V *** hydrogen electrode(RHE),a remarkably high selectivity over 95%across a wide range of 0.3-0.7 V,an impressively high Faradaic efficiency of 94%,and a notable H_(2)O_(2)productivity of 1571 mmol·gcat^(−1)·h^(−1).These findings highlight the great potential of 2D perovskite oxide nanoflakes as advanced electrocatalysts for 2e−oxygen reduction reaction.

关键词： perovskite oxide H_(2)O_(2) two-electron oxygen reduction reaction catalyst Ca_(2)Nb_(3-x)Ta_(x)O_(10)-nanoflakes

EDFW-YOLO: enhancing YOLOv8 for quantitative analysis of surface defects in hot-rolled strips

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

Optoelectronics Letters 2024年

作者： Zhu Jiahao Ma Dongmei Zheng Zhitao wang denghui College of Physics and Electronic Engineering， Northwest Normal University

Detecting surface defects on steel， especially in complex loading environments， poses significant challenges. In response， we introduce EDFW-YOLO， an algorithm built upon YOLOv8 specifically designed for detecting surface defects on hot-rolled steel strips. Our method enhances multi-scale feature fusion through the incorporation of the multi-scale conversion module C2f-EMSC. Additionally， we elevate detection accuracy by integrating the Dynamic Head target detection head， the Focal Modulation module， and the WIoU＿Loss bounding box regression function. Experimental results on the NEU-DET dataset demonstrate that our optimized YOLOv8 model achieves an average accuracy (mAP) of 77.7%， with a 5.2% increase in network constraint rate. To adapt to different operating environments， it further improved the average accuracy (mAP) to 78.5% through data enhancement. Verification results on PCB defect data show that the algorithm has excellent generalization ability. This optimized algorithm significantly improves the extraction and fusion of surface defect features on hot-rolled strip steel and serves as a valuable reference for surface defect detection in alloy materials.

关键词：

Experimental studies of ash film fractions based on measurement of cenospheres geometry in pulverized coal combustion

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Frontiers in Energy 2021年第1期15卷 91-98页

作者： Siqi LIU Yanqing NIU Liping WEN Yang LIANG Bokang YAN denghui wang Shi'en HUI State Key Laboratory of Multiphase Flow in Power Engineering Department of Thermal EngineeringSchool of Energy and Power EngineeringXi'an Jiaotong UniversityXi'an 710049China

In pulverized coal particle combustion, part of the ash forms the ash film and exerts an inhibitory influence on combustion by impeding the diffusion of oxygen to the encapsulated char core, while part of the ash diffuses toward the char core. Despite the considerable ash effects on combustion, the fraction of ash film still remains unclear. However, the research of the properties of cenospheres can be an appropriate choice for the fraction determination, being aware that the formation of cenospheres is based on the model of coal particles with the visco-plastic ash film and a solid core. The fraction of ash film X is the ratio of the measuring mass of ash film and the total ash in coal particle. In this paper, the Huangling bituminous coal with different sizes was burnt in a drop-tube furnace at 1273, 1473, and 1673 K with air as oxidizer. A scanning electron microscope (SEM) and cross-section analysis have been used to study the geometry of the collected cenospheres and the effects of combustion parameters on the fraction of ash film. The results show that the ash film fraction increases with increasing temperature and carbon conversion ratio but decreases with larger sizes of coal particles. The high fraction of ash film provides a reasonable explanation for the extinction event at the late burnout stage. The varied values of ash film fractions under different conditions during the dynamic combustion process are necessary for further development of kinetic models.

关键词： ash film fraction cenospheres coal combustion fly ash

炭化/活化温度对碳酸钾活化玉米芯生物炭吸附苯的性能影响

在线全文

学校读者我要写书评

暂无评论

煤炭学报 2023年第6期48卷 2388-2396页

作者：黄钰坪王登辉西安交通大学能源与动力工程学院陕西西安710049

生物炭作为一种新兴的碳质吸附剂,具有良好的VOCs控制功能。以玉米芯为原料,制备了一系列生物炭(BCx)和碳酸钾活化生物炭(KBC-x-y)(其中,x为炭化温度,y为活化温度)用于吸附苯。利用热重分析、氮气吸附-脱附、扫描电镜(SEM)以及元素分析(... 详细信息

生物炭作为一种新兴的碳质吸附剂,具有良好的VOCs控制功能。以玉米芯为原料,制备了一系列生物炭(BCx)和碳酸钾活化生物炭(KBC-x-y)(其中,x为炭化温度,y为活化温度)用于吸附苯。利用热重分析、氮气吸附-脱附、扫描电镜(SEM)以及元素分析(EA)等方法获得了生物炭(质)样品的热解特性、比表面积、孔容孔径、表面形态及原子占比等,通过吸附实验考察炭化温度/活化温度对生物炭吸附苯的影响。结果表明:碳酸钾活化后的生物炭比表面积最高可达576.76 m^(2)/g,孔容积为0.325 m^(3)/g,对苯的最大吸附量达到82.51 mg/g(较未活化生物炭提升2.9倍);炭化温度与吸附能力呈现正态分布的趋势,吸附能力随着炭化温度的升高而增强,但过高的炭化温度(> 800℃)会导致气孔堵塞、数量减少,比表面积降低,吸附能力下降;低温/高温炭化下,生物炭吸附能力随活化温度变化呈现出相同趋势;高温炭化后(800℃),最佳活化温度为400℃(KBC-800-400),活化温度太高会导致微孔孔壁破碎以及挥发物的烧结效应,从而降低吸附能力,较低的活化温度未能使K2CO3在炭表面充分反应;低温炭化后(400℃),最佳活化温度为(800℃),低温炭化高温活化生物炭(KBC-400-800)吸附性能优于高温炭化低温活化生物炭(KBC-800-400),可能是因为在低温炭化情况下,较高的活化温度有利于碳酸钾参与活化过程反应。

关键词：生物质活化生物炭炭化温度活化温度吸附性能

Single-epoch Integer Ambiguity Resolution for Long-Baseline RTK with Ionosphere and Troposphere Estimation

在线全文

学校读者我要写书评

暂无评论

Single-epoch Integer Ambiguity Resolution for Long-Baseline ...

The Analysis of Ill Posedness in GNSS High-Precision Differential Positioning

第四届中国卫星导航学术年会

作者： denghui wang Chengfa Gao Shuguo Pan School of Transportation Southeast University School of Instrument Science and Engineering Southeast University

A new single-epoch ambiguity resolution for long baseline RTK, on the basis of the ionosphere-weighted model, is proposed in this paper, which is applicable to several hundred km baselines by using linear combination of the measurements, including the double-different wide-lane combination and ionosphere-free combination carrier-phase observation equations and UofC model. By the correct ambiguity and double-different atmosphere delay, the real-time atmosphere model was established to provide a predicted value for new-risen satellite. The establishment of real-time atmosphere predicted model, estimating the relative tropospheric zenith delay and the regional ionospheric parameters, is proved to have an acceptable accuracy. Test data from the multiple reference station GPS networks in Chongqing, consisting of 36 baselines from 40 kilometers to 350 kilometers, were used to evaluate the performance of the proposed approach. It is showed that the proposed algorithm can reduce the effect of the ionosphere and troposphere on the network AR and the true integer ambiguity could be achieved in a short time after the establishment of the predicted atmosphere model.

关键词： Ambiguity resolution Network RTK UofC Real-time atmosphere model

来源： cnki会议评论

在线全文

cnki会议

学校读者我要写书评

暂无评论

The Analysis of Ill Posedness in GNSS High-Precision Differe...

Un-difference PPP Method and Performance Assessment Based on Regional Ionospheric Model

第四届中国卫星导航学术年会

作者： wang Gao Chengfa Gao Shuguo Pan Shengli wang denghui wang School of Transportation Southeast University School of Instrument Science and Engineering Southeast University

GNSS high precision differential positioning generally requires the high-precision float solution and the reasonable covariance matrix for ambiguity integers in short observational time spans. But station-star geometric changes little in short observational time spans, which causes the design matrix to be ill-conditioned seriously during adjustment calculation and lead to the solving of parameter is unstable. With the development of Compass Navigation Satellite System, the GNSS high-precision positioning is now entering the multi-system combined ages. GPS, GLONASS and Compass have different orbits and operating features so that there is some difference from each other in adjustment calculation. The paper combining with the analysis theory on ill-conditioned system, analyses the ill-posedness of GPS, GLONASS and Compass comparatively through a method called spectrum analysis of eigenvalue. The paper reveals the characteristics of the ill-conditioned in several different positioning forms. The conclusion that the faster the satellites runs, the weak the ill-posedness of the parameters solving system will be is presented.

关键词： GNSS double differential positioning Ill posedness Algebraic structure spectrum analysis

来源： cnki会议评论

在线全文

cnki会议

学校读者我要写书评

暂无评论

Un-difference PPP Method and Performance Assessment Based on...

Extraction and Application of UN-Differenced atmospheric Delays with Uncombined Precise Point Positioning Technique

第十一届中国卫星导航年会

作者： Han wang Yun SUI denghui wang Haiyang FU Shaojun FENG Key Laboratory for Information Science of Electromagnetic Waves (MoE) Fudan University Qianxun Spatial Intelligence Inc.

In the field of global navigation satellite system(GNSS), the delay error caused by the ionosphere can reach several meters to several hundred meters, which is the most uncertain error source in GNSS

关键词： Ionospheric delay Precise point positioning Un-difference and uncombination Vertical total electron content model

来源： cnki会议 cnki会议 cnki会议评论

在线全文

学校读者我要写书评

暂无评论

Extraction and Application of UN-Differenced atmospheric Del...