检索结果-南通市图书馆

Pre-reduction of WO_(3)-Co_(3)O_(4)by H_(2)-C_(2)H_4 in a fluidized bed

Chinese Journal of Chemical Engineering 2024年第2期66卷 273-284页

作者： Huijun Shang Hengli li Weijun li feng Pan Zhan Du State Key Laboratory of Multiphase Complex Systems Institute of Process EngineeringChinese Academy of Sciences(CAS)Beijing 100190China College of Chemical Engineering Nanjing Technology UniversityNanjing 211816China School of Chemistry and Chemical Engineering Shihezi UniversityShihezi 832003China College of Chemical Engineering University of Chinese Academy of SciencesBeijing 100049China Chinalco Environmental Protection and Energy Conservation Group Co. Ltd.Xiong’an 071700China

In order to avoid the formation ofηphase(W_(6)Co_(6)C or W_(3)Co_(3)C)that adversely affects the sintering process and its products in the preparation process of ultra-fine WC-Co powder,a technical route of prereduction of WO_(3)-Co_(3)O_(4)to WO_(2)-Co and then deep reduction carbonization to WC-Co powder has been *** study mainly investigates the influence of gas partial pressure on the pre-reduction process of WO_(3)-Co_(3)O_(4)under a mixed atmosphere of H_(2)-C_(2)H_(4)-Ar at 600℃and establishes the kinetic equations of pre-reduction and carbon *** results indicate that increasing the partial pressure of hydrogen is conducive to the rapid and complete conversion of WO_(3) to WO_(2).High carbon content can be generated by the deposition of C_(2)H_(4),and it hinders the diffusion of the reducing gas;WO_(3)still cannot be completely reduced to WO_(2)as the partial pressure of C_(2)H_(4) increases to 60%.For the carbon evolution of C_(2)H_(4),the carbon amount is positively related to the H_(2)partial pressure,but it shows the highest amount and evolution rate when the ethylene partial pressure is 20%.Based on the reduction rate curves of WO_(3) and carbon evolution rate curves of C_(2)H_(4),the rate equations of pre-reduction and carbon evolution of WO_(3)-Co_(3)O_(4)system at 600℃are *** pre-reduction reaction belongs to the first-order reaction,and its equation is expressed as follows:r=-(dw_(WO_(3)))/dt=(9±0.15)×10^(-2)×P_(H_(2))^(0.44)P_(C_(2)H_(4))&(0.57)The carbon deposition rate equation of C_(2)H_(4) can be expressed as follows:r=-(dc_C)/dt=r_f-r_b≌7.35×10^(-2)×P_(C_(2)H_(4))^(0.31)

关键词： Fluidization WO_(3)-Co_(3)O_(4) Reduction Carbon deposition Rate equation

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Application of GNSS-PPP on Dynamic Deformation Monitoring of Offshore Platforms

引用

China Ocean Engineering 2024年第2期38卷 352-361页

作者： YU li-na XIONG Kuan GAO Xi-feng li Zhi FAN li-long ZHANG Kai Institute of Ocean Energy and Intelligent Construction Tianjin University of TechnologyTianjin 300384China China Railway Construction Bridge Engineering Bureau Group Co.LTD Tianjin 300300China School of Civil Engineering Tianjin UniversityTianjin 300072China Department of Land Surveying and Geo-Informatics The Hong Kong Polytechnic UniversityHong KongChina State Key Laboratory of Precision Blasting Jianghan UniversityWuhan 430056China

The real-time dynamic deformation monitoring of offshore platforms under environmental excitation is crucial to their safe *** Global Navigation Satellite System-Precise Point Positioning(GNSS-PPP)has been considered for this purpose,its monitoring accuracy is relatively ***,the influence of background noise on the dynamic monitoring accuracy of GNSS-PPP remains ***,it is imperative to further validate the feasibility of GNSS-PPP for deformation monitoring of offshore *** address these concerns,vibration table tests with different amplitudes and frequencies are *** results demonstrate that GNSS-PPP can effectively monitor horizontal vibration displacement as low as±30 mm,which is consistent with ***,the spectral characteristic of background noise in GNSS-PPP is similar to that of GNSS-RTK(Real Time Kinematic).Building on this observation,an improved Complete Ensemble Empirical Mode Decomposition with Adaptive Noise(CEEMDAN)has been proposed to de-noise the data and enhance the dynamic monitoring accuracy of *** monitoring application research is also undertaken,successfully extracting and analyzing the dynamic deformation of an offshore platform structure under environmental excitation using GNSS-PPP monitoring in conjunction with improved CEEMDAN *** comparing the de-noised dynamic deformation trajectories of the offshore platform during different periods,it is observed that the platform exhibits reversible alternating vibration responses under environmental excitation,with more pronounced displacement deformation in the direction of load *** research results confirm the feasibility and potential of GNSS-PPP for dynamic deformation monitoring of offshore platforms.

关键词： GNSS-PPP offshore platform dynamic deformation monitoring improved CEEMDAN de-noising

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Threshold Selection and Resource Allocation for Quantized Identification

引用

Journal of Systems Science & Complexity 2024年第1期37卷 204-229页

作者： WANG Ying li Xin ZHAO Yanlong ZHANG Ji-feng Key Laboratory of Systems and Control Institute of Systems ScienceAcademy of Mathematics and Systems ScienceChinese Academy of SciencesBeijing 100190China School of Mathematical Sciences University of Chinese Academy of SciencesBeijing 100049China

This paper is concerned with the optimal threshold selection and resource allocation problems of quantized identification, whose aims are improving identification efficiency under limited resources. Firstly, the first-order asymptotically optimal quantized identification theory is extended to the weak persistent excitation condition. Secondly, the characteristics of time and space complexities are established based on the Cramér-Rao lower bound of quantized systems. On these basis, the optimal selection methods of fixed thresholds and adaptive thresholds are established under aperiodic signals, which answer how to achieve the best efficiency of quantized identification under the same time and space complexity. In addition, based on the principle of maximizing the identification efficiency under a given resource, the optimal resource allocation methods of quantized identification are given for the cases of fixed thresholds and adaptive thresholds, respectively, which show how to balance time and space complexity to realize the best identification efficiency of quantized identification.

关键词： Quantized output resource allocation system identification threshold selection.

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Fortifying Smart Grids: A Holistic Assessment Strategy against Cyber Attacks and Physical Threats for Intelligent Electronic Devices

引用

Computers, Materials & Continua 2024年第8期80卷 2579-2609页

作者： Yangrong Chen June li Yu xia.Ruiwen Zhang lingling li xia.yu li lin Ge School of Computer Science Zhengzhou University of AeronauticsZhengzhou450046China Henan Xin’an Century Technology Co. Ltd.Henan Data Security Engineering Technology Research CenterZhengzhou450046China Key Laboratory of Aerospace Information Security and Trusted Computing Ministry of EducationSchool of Cyber Science and EngineeringWuhan UniversityWuhan430072China

Intelligent electronic devices(IEDs)are interconnected via communication networks and play pivotal roles in transmitting grid-related operational data and executing control *** the context of the heightened security challenges within smart grids,IEDs pose significant risks due to inherent hardware and software vulner-abilities,as well as the openness and vulnerability of communication *** grid security,distinct from traditional internet security,mainly relies on monitoring network security events at the platform layer,lacking an effective assessment mechanism for ***,we incorporate considerations for both cyber-attacks and physical faults,presenting security assessment indicators and methods specifically tailored for ***,we outline the security monitoring technology for IEDs,considering the necessary data sources for their security ***,we classify IEDs and establish a comprehensive security monitoring index system,incorporating factors such as running states,network traffic,and abnormal *** index system contains 18 indicators in 3 ***,we elucidate quantitative methods for various indicators and propose a hybrid security assessment method known as GRCW-hybrid,combining grey relational analysis(GRA),analytic hierarchy process(AHP),and entropy weight method(EWM).According to the proposed assessment method,the security risk level of IEDs can be graded into 6 levels,namely 0,1,2,3,4,and *** higher the level,the greater the security ***,we assess and simulate 15 scenarios in 3 categories,which are based on monitoring indicators and real-world situations encountered by *** results show that calculated security risk level based on the proposed assessment method are consistent with actual ***,the reasonableness and effectiveness of the proposed index system and assessment method are validated.

关键词： Smart grid intelligent electronic device security assessment abnormal behaviors network traffic running states

来源：

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

Temporal assembly patterns of microbial communities in three parallel bioreactors treating low-concentration coking wastewater with differing carbon source concentrations

引用

Journal of Environmental Sciences 2024年第3期137卷 455-468页

作者： Weijia li Yu xia.Na li Jie Chang Jing liu Pei Wang Xuwen He School of Chemical and Environmental Engineering China University of Mining and Technology-BeijingBeijing 100083China

Carbon source is an important factor of biological treatment systems, the effects of which on their temporal community assembly patterns are not sufficiently understood *** this study, the temporal dynamics and driving mechanisms of the communities in three parallel bioreactors for low-concentration coking wastewater(CWW) treatment with differing carbon source concentrations(S0 with no glucose addition, S1 with 200 mg/L glucose addition and S2 with 400 mg/L glucose addition) were comprehensively studied. Highthroughput sequencing and bioinformatics analyses including network analysis and Infer Community Assembly Mechanisms by Phylogenetic bin-based null model(iCAMP) were used. The communities of three systems showed turnover rates of 0.0029~0.0034 every 15days. Network analysis results showed that the S0 network showed higher positive correlation proportion(71.43%) and clustering coefficient(0.33), suggesting that carbon source shortage in S0 promoted interactions and cooperation of microbes. The neutral community model analysis showed that the immigration rate increased from 0.5247 in S0 to 0.6478in S2. The iCAMP analysis results showed that drift(45.89%) and homogeneous selection(31.68%) dominated in driving the assembly of all the investigated microbial *** contribution of homogeneous selection increased with the increase of carbon source concentrations, from 27.92% in S0 to 36.08% in S2. The OTUs participating in aerobic respiration and tricarboxylic acid(TCA) cycle were abundant among the bins mainly affected by deterministic processes, while those related to the metabolism of refractory organic pollutants in CWW such as alkanes, benzenes and phenols were abundant in the bins dominated by stochastic processes.

关键词： Coking wastewater treatment Temporal dynamics Network analysis Deterministic processes Stochastic processes

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

FusionNN:A Semantic Feature Fusion Model Based on Multimodal for Web Anomaly Detection

引用

Computers, Materials & Continua 2024年第5期79卷 2991-3006页

作者： li Wang Mingshan xia.Hao Hu Jianfang li fengyao Hou Gang Chen Institute of High Energy Physics Chinese Academy of SciencesBeijing100049China Spallation Neutron Source Science Center(SNSSC) Dongguan523803China School of Nuclear Technology University of Chinese Academy of SciencesBeijing100049Chin

With the rapid development of the mobile communication and the Internet,the previous web anomaly detectionand identificationmodels were built relying on security experts’empirical knowledge and attack *** approach can achieve higher detection performance,it requires huge human labor and resources to maintainthe feature *** contrast,semantic feature engineering can dynamically discover new semantic featuresand optimize feature selection by automatically analyzing the semantic information contained in the data itself,thus reducing dependence on prior ***,current semantic features still have the problem ofsemantic expression singularity,as they are extracted from a single semantic mode such as word segmentation,character segmentation,or arbitrary semantic feature *** paper extracts features of web requestsfrom dual semantic granularity,and proposes a semantic feature fusion method to solve the above *** first preprocesses web requests,and extracts word-level and character-level semantic features of URLs viaconvolutional neural network(CNN),*** constructing three loss functions to reduce losses betweenfeatures,labels and *** on the HTTP CSIC 2010,Malicious URLs and HttpParams datasetsverify the *** show that compared withmachine learning,deep learningmethods and BERTmodel,the proposed method has better detection *** it achieved the best detection rate of 99.16%in the dataset HttpParams.

关键词： Feature fusion web anomaly detection multimodal convolutional neural network(CNN) semantic feature extraction

来源：

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

Contributors to tidal duration asymmetry with varied coastline configurations on western shelf of Yellow Sea

引用

Water Science and Engineering 2024年第1期17卷 1-12页

作者： Xi feng Zheng li Hui feng Jia-yan Yang Shou-peng Xie Wei-bing feng College of Harbor.Coastal and Offshore Engineering Hohai UniversityNanjing 210098China China Harbour Engineering Co. LtdBeijing 100027China Key Laboratory of Port Waterway and Sedimentation Engineering of the Ministry of CommunicationsNanjing 210029China China South-to-North Water Diversion Corporation limited Beijing 100036China

Coastal management in China is confronted with an urgent choice between natural restoration and maintenance of existing seawalls and reclaimed land for economic development.A key criterion for making this decision is the resilience to coastal flooding,which depends on the ability to predict tidal *** duration asymmetry(TDA)is a key parameter in determination of the arrival and duration of flood *** study selected the western inner shelf of the Yellow Sea(WYS)as the study area and investigated the responses of TDA to different shoreline configurations and relative sea level *** responses of TDA to shoreline reconstruction yielded spatial variability locally and *** the nearshore area,the responses of TDA to the complex ocean environment mainly originated from the combined functions of reflection,bottom friction,and advection,which controlled the energy transfer from M2 or S2 constituents to their overtides or compound *** sensitivity of TDA to coastline typologies was not limited to coastal waters but could stretch over the entire inner *** vulnerability of tidal responses was due to the displacement of the M2 amphidrome of the Kelvin wave on the WYS,which in turn changed tidal energy fluxes over the *** relative sea level rise could intensify the feedback of TDA to seawalls and land reclamation.

关键词： Tidal duration asymmetry Western inner shelf of Yellow Sea Natural restoration Relative sea level rise Tidal amphidrome

来源：

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

Audio-visual keyword transformer for unconstrained sentence-level keyword spotting

引用

CAAI Transactions on Intelligence Technology 2024年第1期9卷 142-152页

作者： Yidi li Jiale Ren Yawei Wang Guoquan Wang xia.li Hong liu Key Laboratory of Machine Perception Peking UniversityShenzhen Graduate SchoolShenzhenChina College of Electronics and Information Engineering Sichuan UniversityChengduChina Department of Computer Science ETH ZurichZurichSwitzerland

As one of the most effective methods to improve the accuracy and robustness of speech tasks,the audio-visual fusion approach has recently been introduced into the field of Keyword Spotting(KWS).However,existing audio-visual keyword spotting models are limited to detecting isolated words,while keyword spotting for unconstrained speech is still a challenging *** this end,an Audio-Visual Keyword Transformer(AVKT)network is proposed to spot keywords in unconstrained video *** authors present a transformer classifier with learnable CLS tokens to extract distinctive keyword features from the variable-length audio and visual *** outputs of audio and visual branches are combined in a decision fusion *** humans can easily notice whether a keyword appears in a sentence or not,our AVKT network can detect whether a video clip with a spoken sentence contains a pre-specified ***,the position of the keyword is localised in the attention map without additional position ***-imental results on the LRS2-KWS dataset and our newly collected PKU-KWS dataset show that the accuracy of AVKT exceeded 99%in clean scenes and 85%in extremely noisy *** code is available at https://***/jialeren/AVKT.

关键词： artificial intelligence multimodal approaches natural language processing neural network speech processing

来源：

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

Electroencephalogram findings in 10 patients with post-stroke epilepsy:A retrospective study

引用

World Journal of Clinical Cases 2024年第2期12卷 249-255页

作者： li-Min Wen Ran li Yan-ling Wang Qing-xia.Kong Min xia Clinical Medicine College Jining Medical UniversityJining 272067Shandong ProvinceChina School of Basic Medical Sciences Shandong UniversityJinan 250012Shandong ProvinceChina Department of Neurology The Affiliated Hospital of Jining Medical UniversityJining 272007Shandong ProvinceChina

BACKGROUND Post-stroke epilepsy is a common and easily overlooked complication of acute cerebrovascular ***-term seizures can seriously affect the prognosis and quality of life of ***(EEG)is the simplest way to diagnose epilepsy,and plays an important role in predicting seizures and guiding *** To explore the EEG characteristics of patients with post-stroke epilepsy and improve the detection rate of inter-seizure epileptiform *** From January 2017 to June 2020,10 patients with post-stroke epilepsy in our hospital were *** clinical,imaging,and EEG characteristics were *** stroke location,seizure type,and ictal and interictal EEG manifestations of the patients with post-stroke epilepsy were then retrospectively *** In all 10 patients,epileptiform waves occurred in the side opposite to the stroke lesion during the interictal stage;these manifested as sharp wave,sharp-wave complex,or spike discharges in the anterior head lead of the side opposite to the *** In EEG,epileptiform waves can occur in the side opposite to the stroke lesion in patients with post-stroke epilepsy.

关键词： Post-stroke epilepsy Electroencephalogram Seizure Stroke Slow wave

来源：

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

Mucosa color and size may indicate malignant transformation of chicken skin mucosa-positive colorectal neoplastic polyps

引用

World Journal of Gastrointestinal Oncology 2024年第3期16卷 750-760页

作者： Ying-Jie Zhang Meng-xia.Yuan Wu Wen Fan li Yi Jian Chuan-Ming Zhang Ye Yang feng-lin Chen Department of Digestive Diseases Chengdu Second People’s HospitalChengdu 610000Sichuan ProvinceChina Graduate School Chengdu Medical CollegeChengdu 610000Sichuan ProvinceChina

BACKGROUND lipid metabolism reprogramming is suspected to exist in pre-cancerous lesions,including colorectal *** colonoscopy frequently reveals chicken skin mucosa(CSM;white or yellow-white speckled mucosa)surrounding colo-rectal polyps,caused by macrophages engulfing and accumulating the lipids decomposed by colon cells or adjacent ***-positive colorectal polyps are associated with various diseases;however,their prognosis varies *** snare polypectomy is commonly used to resect lesions up to 10 to 15 mm in diameter without signs of submucosal invasion but is controversial for CSM-positive colorectal *** imaging is required to diagnose and treat CSM-positive colorectal *** This retrospective cohort study included 177 patients with CSM-positive colorectal polyps diagnosed using *** patient-related information was extracted from the Goldisc soft-clinic DICOM system or electronic medical record *** on the pathological results,patients were classified as non-neoplastic polyps(five juvenile polyps),neoplastic polyps,non-invasive high-grade neoplasia(NHGN),or submucosal invasive carcinoma(SM stage cancer).We analyzed and compared the clinical features,suspected risk factors for malignant transformation of neoplastic polyps,and early infiltration of sub-mucosal *** The diameters of NHGN and SM polyps were much smaller than those of neoplastic *** NHGN polyps had a deeper red mucosal *** logistic regression analyses,diameter and deeper red mucosal color were independent risk factors for malignant transformation of neoplastic *** 1 CSM was more common in high-grade intraepithelial neoplasia and SM;type 2 CSM was more common in neoplastic *** regression analyses revealed no significant differences in the malignant transformation of neoplastic polyps or early submucosal invasion of CSM-positive colorectal *** in the CSM mucosa surrounding neoplastic

关键词： Chicken skin mucosa Colorectal cancer Colorectal polyps Endoscopic resection Malignant transformation White light endoscopy

来源：

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

欢迎您,

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案：

请选择收藏分类：

通借通还

欢迎您,

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：