检索结果-南通市图书馆

Spectrum analysis of interval process model and its application in uncertain vibration analysis

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

Science China(Technological Sciences) 2024年第8期67卷 2549-2564页

作者： LI JinWu JIANG Chao ni BingYu State Key Laboratory of Advanced Design and Manufacturing Technology for Vehicle College of Mechanical and Vehicle EngineeringHunan UniversityChangsha 410082China

In recent years, the authors have extended the traditional interval method into the time dimension to develop a new mathematical tool called the “interval process model” for quantifying time-varying or dynamic uncertainties. This model employs upper and lower bounds instead of precise probability distributions to quantify uncertainty in a parameter at any given time point. It is anticipated to complement the conventional stochastic process model in the coming years owing to its relatively low dependence on experimental samples and ease of understanding for engineers. Building on our previous work, this paper proposes a spectrum analysis method to describe the frequency domain characteristics of an interval process, further strengthening the theoretical foundation of the interval process model and enhancing its applicability for complex engineering problems. In this approach, we first define the zero midpoint function interval process and its auto/cross-power spectral density(PSD) functions. We also deduce the relationship between the auto-PSD function and the auto-covariance function of the stationary zero midpoint function interval process. Next, the auto/cross-PSD function matrices of a general interval process are defined, followed by the introduction of the concepts of PSD function matrix and cross-PSD function matrix for interval process vectors. The spectrum analysis method is then applied to random vibration problems, leading to the creation of a spectrum-analysis-based interval vibration analysis method that determines the PSD function for the system displacement response under stationary interval process excitations. Finally, the effectiveness of the formulated spectrum-analysis-based interval vibration analysis approach is verified through two numerical examples.

关键词： interval process spectrum analysis power spectral density(PSD) time-varying uncertainty uncertain vibration analysis

同方期刊数据库

在线全文

学校读者我要写书评

暂无评论

城乡收入差距加剧还是抑制了大气污染?

中国人口·资源与环境 2021年第10期31卷 130-138页

作者：井波倪子怡赵丽瑶刘凯山东师范大学地理与环境学院山东济南250358 山东师范大学“人地协调与绿色发展”山东省高校协同创新中心山东济南250358

在全面建成小康社会的新形势下,城乡收入差距已经成为中国转型过程中影响社会全面进步的重要因素,并且目前处于城镇化和工业化的快速发展阶段,经济增长带来的生态环境问题依然较为严重。因此,缩小城乡收入差距、治理大气污染成为中国必... 详细信息

在全面建成小康社会的新形势下,城乡收入差距已经成为中国转型过程中影响社会全面进步的重要因素,并且目前处于城镇化和工业化的快速发展阶段,经济增长带来的生态环境问题依然较为严重。因此,缩小城乡收入差距、治理大气污染成为中国必须大力解决的问题。该研究以2003—2018年中国274个地级以上城市面板数据为研究对象,以城镇居民人均可支配收入和农村居民人均可支配收入比值反映城乡收入差距,以PM_(2.5)浓度反映大气污染,运用时期固定效应的空间杜宾模型模拟城乡收入差距对大气污染的影响。研究表明,在控制了经济增长、产业结构、对外开放程度、技术进步、能源利用、环境规制等变量后,城乡收入差距对大气污染具有显著的正向影响,扩大城乡收入差距将会明显带来大气污染程度提高,加入核心解释变量的二次项和替换核心解释变量后依然证实了这一结论,并且西部地区这种正向影响比东部和中部地区更加明显。说明缩小城乡收入差距和治理大气污染在政策目标上具有趋同性,需要切实提高农民收入,提高农村地区环境规制水平,提高农民环保意识。

关键词：城乡收入差距大气污染二元结构环境质量空间杜宾模型

Rethinking the Encoder-decoder Structure in Medical Image Segmentation from Releasing Decoder Structure

在线全文

学校读者我要写书评

暂无评论

Journal of Bionic Engineering 2024年第3期21卷 1511-1521页

作者： Jiajia ni Wei Mu An Pan Zhengming Chen School of Artificial Intelligence Anhui Polytechnic UniversityWuhu241000China School of Information Science and Engineering HoHai UniversityChangzhou213000China

Medical image segmentation has witnessed rapid advancements with the emergence of encoder-decoder based *** the encoder-decoder structure,the primary goal of the decoding phase is not only to restore feature map resolution,but also to mitigate the loss of feature information incurred during the encoding ***,this approach gives rise to a challenge:multiple up-sampling operations in the decoder segment result in the loss of feature *** address this challenge,we propose a novel network that removes the decoding structure to reduce feature information loss(CBL-Net).In particular,we introduce a Parallel Pooling Module(PPM)to counteract the feature information loss stemming from conventional and pooling operations during the encoding ***,we incorporate a Multiplexed Dilation Convolution(MDC)module to expand the network's receptive ***,although we have removed the decoding stage,we still need to recover the feature map ***,we introduced the Global Feature Recovery(GFR)*** uses attention mechanism for the image feature map resolution recovery,which can effectively reduce the loss of feature *** conduct extensive experimental evaluations on three publicly available medical image segmentation datasets:DRIVE,CHASEDB and MoNuSeg *** results show that our proposed network outperforms state-of-the-art methods in medical image *** addition,it achieves higher efficiency than the current network of coding and decoding structures by eliminating the decoding component.

关键词： Medical image segmentation Encoder-decoder architecture Attention mechanisms Releasing decoder architecture Neural network

Bulging Distortion of Austenitic Stainless Steel Sheet on the Partially Penetrated Side of Non-Penetration Lap Laser Welding Joint

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 Mechanical Engineering 2024年第1期37卷 286-295页

作者： Chengwu Yao Enze Liu Jiaming ni Binying nie Shanghai Key Laboratory of Materials Laser Processing and Modification School of Material Science and EngineeringShanghai Jiao Tong UniversityShanghai 200240China Shanghai Aerospace Precision Machinery Institute Shanghai 201600China Chemical and Biological Engineering College Yichun UniversityYichun 336000China

Non-penetration laser welding of lap joints in austenitic stainless steel sheets is commonly preferred in fields where the surface quality is of utmost ***,the application of non-penetration welded austenitic stainless steel parts is limited owing to the micro bulging distortion that occurs on the back surface of the partial penetration *** this paper,non-penetration lap laser welding experiments,were conducted on galvanized and SUS304 austenitic stainless steel plates using a fiber laser,to investigate the mechanism of bulging distortion.A comparative experiment of DC01 galvanized steel-Q235 carbon steel lap laser welding was carried out,and the deflection and distortion profile of partially penetrated side of the sheets were measured using a noncontact laser *** addition,the cold-rolled SUS304 was subjected to heat holding at different temperatures and water quenching after bending to characterize its microstructure under tensile and compressive *** results show that,during the heating stage of the thermal cycle of laser lap welding,the partial penetration side of the SUS304 steel sheet generates compressive stress,which extrudes the material in the heat-affected zone to the outside of the back of the SUS304 steel sheet,thereby forming a *** findings of these experiments can be of great value for controlling the distortion of the partial penetrated side of austenitic stainless steel sheet during laser non-penetration lap welding.

关键词： Non-penetration lap laser welding Bulging distortion Austenitic stainless steel Compressive stress Tension stress

Classification of aviation incident causes using LGBM with improved cross-validation

在线全文

学校读者我要写书评

暂无评论

Journal of Systems Engineering and Electronics 2024年第2期35卷 396-405页

作者： ni Xiaomei WANG Huawei CHEN Lingzi LIN Ruiguan School of Civil Aviation Nanjing University of Aeronautics and AstronauticsNanjing 211106China School of Aeronautical Engineering Nanjing Vocational University of Industry TechnologyNanjing 210023China

Aviation accidents are currently one of the leading causes of significant injuries and deaths worldwide. This entices researchers to investigate aircraft safety using data analysis approaches based on an advanced machine learning *** assess aviation safety and identify the causes of incidents, a classification model with light gradient boosting machine (LGBM)based on the aviation safety reporting system (ASRS) has been developed. It is improved by k-fold cross-validation with hybrid sampling model (HSCV), which may boost classification performance and maintain data balance. The results show that employing the LGBM-HSCV model can significantly improve accuracy while alleviating data imbalance. Vertical comparison with other cross-validation (CV) methods and lateral comparison with different fold times comprise the comparative approach. Aside from the comparison, two further CV approaches based on the improved method in this study are discussed:one with a different sampling and folding order, and the other with more CV. According to the assessment indices with different methods, the LGBMHSCV model proposed here is effective at detecting incident causes. The improved model for imbalanced data categorization proposed may serve as a point of reference for similar data processing, and the model’s accurate identification of civil aviation incident causes can assist to improve civil aviation safety.

关键词： aviation safety imbalance data light gradient boosting machine(LGBM) cross-validation(CV)

Oxidation of emerging organic contaminants by in-situ H_(2)O_(2) fenton system

在线全文

学校读者我要写书评

暂无评论

Green Energy & Environment 2024年第3期9卷 417-434页

作者： Yuqin ni Chuxiang Zhou Mingyang Xing Yi Zhou State Environmental Protection Key Lab of Environmental Risk Assessment and Control on Chemical Processes School of Resources&Environmental EngineeringEast China University of Science and TechnologyShanghai200237China Key Laboratory for Advanced Materials and Institute of Fine Chemicals National Engineering Laboratory for Industrial Wastewater TreatmentSchool of Chemistry and Molecular EngineeringEast China University of Science and Technology130 Meilong RoadShanghai200237China Department of Applied Natural Sciences Technische Hochschule LubeckMonkhofer Weg 23923562 LubeckGermany

The existence and risk of emerging organic contaminants(EOCs)have been under consideration and paid much effort to degrade these *** system is one of the most widely used technologies to solve this *** original Fenton system relies on the hydroxyl radicals produced by Fe(Ⅱ)/H_(2)O_(2) to oxidize the organic ***,the application of the Fenton system is limited by its low iron cycling efficiency and the high risks of hydrogen peroxide transportation and *** introduction of external energy(including light and electricity etc.)can effectively promote the Fe(Ⅲ)/Fe(Ⅱ)cycle and the reduction of oxygen to produce hydrogen peroxide in *** review introduces three in-situ Fenton systems,which are electro-Fenton,Photo-Fenton,and chemical *** mechanism,influencing factors,and catalysts of these three in-situ Fenton systems in degrading EOCs are discussed *** review strengthens the understanding of Fenton and in-situ Fenton systems in degradation,offering further insight into the real application of the in-situ Fenton system in the removal of EOCs.

关键词： In-situ H_(2)O_(2)production Fenton Emerging organic contaminants Photocatalysis Electrocatalysis

Stimulating Start-up Investment Through Government-Sponsored Venture Capital: Theory and Chinese Evidence

在线全文

学校读者我要写书评

暂无评论

Journal of Systems Science & Complexity 2024年第5期37卷 2021-2053页

作者： ni Xuanming ZHENG Tiantian GAO Feng ZHAO Huimin School of Software and Microelectronics Peking University School of Economics and Management Tsinghua University School of Business Sun Yat-sen University

Government-sponsored venture capital(GVC) has been used to support financially constrained start-ups as an important policy tool in China. Typically, to motivate the social capital to invest in start-ups, GVC provides subsidies for them to bridge the funding gap in the early-stage venture capital market. However, the effect and mechanism of GVC affecting social capital investment have not been clearly studied. In this paper, the authors not only develop a game model to analyze this issue in theory, but conduct an empirical study by analyzing the 14741 records matched by propensity score matching(PSM) of Chinese venture capital market data from 2011 to 2021. The proposed findings are as the follows. Firstly, the subsidies offered by GVC will simultaneously increase the returns and risks of investments in start-ups of social capital with more volatile incentive effect of GVC. The incentive effect of GVC is only effective when the returns resulting from the subsidies outweigh the risks they introduce. In the context of the Chinese venture capital market, the incentive effect of GVC is effective. Secondly, the incentive effect of GVC is more pronounced in high-tech industries, which can be attributed to the signaling effect facilitated by GVC. In this context, the subsidy mainly helps social capital to bear the costs associated with screening potential investments. Thirdly, the incentive effect of GVC is more significant in underdeveloped venture capital markets, which can be explained by the “virtuous cycle” effect, in which GVC plays a pioneering role in establishing a more robust early-stage market trading system. By examining these three points, this study contributes to a better understanding of how GVC can effectively guide social capital investment, especially in the Chinese landscape.

关键词： Government-sponsored venture capital fund incentive effect social capital subsidy venture capital

Characteristics and mechanism of ni^(2+)and Cd^(2+)adsorption by recovered perlite from agar extraction residue

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Chinese Journal of Chemical Engineering 2024年第8期72卷 141-152页

作者： Juan Wang Yanbing Zhu Zedong Jiang Xiping Du Mingjing Zheng Lijun Li Hui ni Yuanpeng Wang Zhipeng Li Qingbiao Li College of Ocean Food and Biological Engineering Jimei UniversityXiamen 361021China Fujian Provincial Key Laboratory of Food Microbiology and Enzyme Engineering Xiamen 361021China Research Center of Food Biotechnology of Xiamen City Xiamen 361021China Xiamen Ocean Vocational College Xiamen 361021China College of Chemistry and Chemical Engineering Xiamen UniversityXiamen 361021China

ni^(2+)and Cd^(2+)in wastewater accumulated through the ecological chain and could jeopardize human *** of ni^(2+)and Cd^(2+)from wastewater using recovered perlite was an important way to solve the problem of resource utilization of solid waste from agar *** previous study confirmed that recovered perlite from agar extraction residue had better pore size and specific surface area than commercial ***,the adsorption efficiency and adsorption mechanism of recovered perlite were the main factors limiting its adsorption *** adsorption process of ni^(2+)and Cd^(2+)by recovered perlite in aqueous solution was described by the pseudo-second-order kinetic equation,and the relevant adsorption mechanism was mainly *** with commercial perlite,the adsorption removal rate of ni^(2+)and Cd^(2+)by enzymatic recovered perlite could reach 92.9%and 89.2%,respectively,and were improved by 12.63%and 13.03%.Langmuir isothermal adsorption model could better describe the isothermal adsorption process of recovered perlite on heavy metal ni^(2+)and Cd^(2+),and the relevant adsorption mechanism was mainly monolayer *** X-ray photoelectron spectroscopy(XPS)results indicated that the decrease of Si—O Si^(2+)hydroxyl coordination bond and the increase of C—Si bond might make the binding effect of recovered perlite with heavy metals *** competitive adsorption of ni^(2+)and Cd^(2+)by recovered perlite was still dominated by chemisorption and monolayer *** study was expected to provide a theoretical basis and technical support for the removal of ni^(2+)and Cd^(2+)from wastewater using recovered perlite from seaweed residue.

关键词： Agar extraction residue Recovered perlite Heavy metal ion Adsorption property

Advances in non-invasive imaging of proteinopathies in animal models of neurodegenerative diseases

在线全文

学校读者我要写书评

暂无评论

Neural Regeneration Research 2024年第10期19卷 2115-2116页

作者： Lei Cao Bin Ji Ruiqing ni Changes Technology Corporation Ltd. ShanghaiChina Fudan University ShanghaiChina School of Pharmacy Fudan UniversityShanghaiChina Institute for Biomedical Engineering University of Zurich&ETH Zurich Institute for Regenerative MedicineUniversity of ZurichZurichSwitzerland

Neurodegenerative diseases,including Alzheimer's disease(AD),frontotemporal dementia,Parkinson's disease,and dementia with Lewy bodies,represent tremendous unmet clinical needs.A common feature of these diseases is the aberrant cerebral accumulation of pathological protein aggregates,affecting selectively vulnerable circuits in a disease-specific *** studies have established a relationship between abnormal aggregation and neuronal dysfunction or loss,suggesting multifactorial pathogenesis mechanisms in these neurodegenerative disorders.

关键词： diseases degenerative clinical