Subjects: Mechanics >> Other Disciplines of Mechanics submitted time 2024-06-17 Cooperative journals: 《应用力学学报》
Abstract： The dynamic snap-through behavior of isotropic shallow shells under thermal shock loading was studied in the present work.The transient heat conduction through the thickness of shell was analyzed first; the thermally induced membrane forces and bending moments were also derived.The classical shell theory was adopted to model the shell and the derived equations of motion accounts for the Karman’s geometrically nonlinear strain.The equations of motion were then transformed into coupled time-dependent nonlinear algebraic equations via the Ritz method,and the latter was numerically solved with the Newmark method and Newton-Raphson’s iterative method.The critical thermal shock condition for the occurrence of dynamic snap-through was identified by the Budiansky-Hutchinson criterion while the computational results were analyzed.It was demonstrated that dynamic snap-through occurs in the shallow shell subjected to strong enough thermal shock,and thermally induced vibration exists during the whole snap-through process.The modeling and analysis methods provided by this study have important reference value for accurately evaluating the stability and dynamic response of engineering shallow shells under thermal shock.
Subjects: Medicine, Pharmacy >> Clinical Medicine submitted time 2024-04-18 Cooperative journals: 《中国全科医学》
Abstract： The outbreak of COVID-19 has had a huge impact globally. After the infection，a considerable number of patients have been affected by a series of lingering symptoms or sequelae with strong heterogeneity，which we temporarily refer to as "Long COVID". Compared to the well-studied cardiovascular complications caused by COVID-19 during the acute phase，the cardiovascular sequelae in "Long COVID" require greater attention. This review includes the clinical manifestations， mechanisms，and principles of diagnosis and management of cardiovascular sequelae in "Long COVID"，aiming to improve the disease's understanding and reduce its harm scientifically.
Subjects: Digital Publishing >> New Media submitted time 2023-10-08 Cooperative journals: 《中国传媒科技》
Abstract：现如今网络技术发展迅速,我国媒体也随之迅速发展,从传统媒体时代进入融媒体时代,随着网络和数字技术爆发式的发展,我国经济社会发展的技术基础也发生了本质的变革,随之带来了大众舆论的重大变化和媒体格局的深刻变革,本文主要说明了以下问题:融媒体、新媒体以及资本运作的概念;融媒体时代下新媒体资本运营的现实情况及特点;深入分析新媒体在资本运营过程中出现的问题;针对性地提出相应的解决策略,希望能为新媒体运营提供一定的理论参考。
Subjects: Agriculture, Forestry,Livestock & Aquatic Products Science >> Basic Disciplines of Agriculture submitted time 2023-08-14 Cooperative journals: 《智慧农业（中英文）》
Abstract： [Objective] Desert vegetation is an indispensable part of desert ecosystems, and its conservation and restoration are crucial. Accurate identification of desert plants is an indispensable task, and is the basis of desert ecological research and conservation. The complex growth environment caused by light, soil, shadow and other vegetation increases the recognition difficulty, and the generalization abili‐ty is poor and the recognition accuracy is not guaranteed. The rapid development of modern technology provides new opportunities for plant identification and classification. By using intelligent identification algorithms, field investigators can be effectively assisted in desert plant identification and classification, thus improve efficiency and accuracy, while reduce the associated human and material costs. [Methods] In this research, the following works were carried out for the recognition of desert plant: Firstly, a training dataset of deep learning model of desert plant images in the arid and semi-arid region of Xinjiang was constructed to provide data resources and basic support for the classification and recognition of desert plant images.The desert plant image data was collected in Changji and Tacheng region from the end of September 2021 and July to August 2022, and named DPlants50. The dataset contains 50 plant species in 13 families and 43 genera with a total of 12,507 images, and the number of images for each plant ranges from 183 to 339. Secondly, a migration integration learning-based algorithm for desert plant image recognition was proposed, which could effectively improve the recognition accuracy. Taking the EfficientNet B0−B4 network as the base network, the ImageNet dataset was pre-trained by migration learning, and then an integrated learning strategy was adopted combining Bagging and Stacking, which was divided into two layers. The first layer introduced K-fold cross-validation to divide the dataset and trained K sub-models by borrowing the Stacking method. Considering that the output features of each model were the same in this study, the second layer used Bagging to integrate the output features of the first layer model by voting method, and the difference was that the same sub-models and K sub-models were compared to select the better model, so as to build the integrated model, reduce the model bias and variance, and improve the recognition performance of the model. For 50 types of desert plants, 20% of the data was divided as the test set, and the remaining 5 fold cross validation was used to divide the dataset, then can use DPi(i=1,2,…,5) represents each training or validation set. Based on the pre trained EfficientNet B0−B4 network, training and validation were conducted on 5 data subsets. Finally, the model was integrated using soft voting, hard voting, and weighted voting methods, and tested on the test set. [Results and Discussions] The results showed that the Top-1 accuracy of the single sub-model based on EfficientNet B0 network was 92.26%~93.35%, the accuracy of the Ensemble-Soft model with soft voting, the Ensemble-Hard model with hard voting and the Ensemble-Weight model integrated by weighted voting method were 93.63%, 93.55% and 93.67%, F1 Score and accuracy were comparable, the accuracy and F1 Score of Ensemble-Weight model integrated by weighted voting method were not significantly improved compared with Ensemble-Soft model and Ensemble-hard model, but it showed that the effect of weighted voting method proposed in this study was better than both of them. The three integrated models demonstrate no noteworthy enhancements in accuracy and F1 Score when juxtaposed with the five sub-models. This observation results suggests that the homogeneity among the models constrains the effectiveness of the voting method strategy. Moreover, the recognition effects heavily hinges on the performance of the Efficient‐ Net B0-DP5 model. Therefore, the inclusion of networks with more pronounced differences was considered as sub-models. A single sub-model based on EfficientNet B0−B4 network had the highest Top-1 accuracy of 96.65% and F1 Score of 96.71%, while Ensemble-Soft model, Ensemble-Hard model and Ensemble-Weight model got the accuracy of 99.07%, 98.91% and 99.23%, which further improved the accuracy compared to the single sub-model, and the F1 Score was basically the same as the accuracy rate, and the model performance was significant. The model integrated by the weighted voting method also improved accuracy and F1 Score for both soft and hard voting, with significant model performance and better recognition, again indicating that the weighted voting method was more effective than the other two. Validated on the publicly available dataset Oxford Flowers102, the three integrated models improved the accuracy and F1 Score of the three sub-models compared to the five sub-models by a maximum of 4.56% and 5.05%, and a minimum of 1.94% and 2.29%, which proved that the migration and integration learning strategy proposed in this paper could effectively improve the model performances. [Conclusions] In this study, a method to recognize desert plant images in natural context by integrating migration learning and integration learning was proposed, which could improve the recognition accuracy of desert plants up to 99.23% and provide a solution to the problems of low accuracy, model robustness and weak generalization of plant images in real field environment. After transferring to the server through the cloud, it can realize the accurate recognition of desert plants and serve the scenes of field investigation, teaching science and scientific experiment.
Subjects: Materials Science >> Materials Science (General) submitted time 2023-03-31 Cooperative journals: 《腐蚀科学与防护技术》
Abstract： The recent status of research on the corrosion of low-alloy corrosion resistant steel was reviewed with an emphasis on its corrosion performance and passivation behavior, thereafter some relevant corrosion mechanisms were summed up. Then, the research concerning modeling for prediction of the service life for the corrosion resistant steel reinforced concrete structures and the related theoretical basis were introduced in terms of corrosion initiation and corrosion propagation, as well as the unique characteristics of the corrosion resistant steel. Finally, several existing issues about corrosion assessment and life time prediction of the corrosion resistant steel reinforced concrete structures are discussed, and the future trends of investigation in the field were also prospected.
Subjects: Materials Science >> Materials Science (General) submitted time 2023-03-31 Cooperative journals: 《腐蚀科学与防护技术》
Abstract： The influence of the ethylene glycol concentration, temperature and the ratio of cathodeto-anode area on galvanic corrosion of two couples of 3A21 Al-alloy/H62 brass (Al/Cu) and 3A21 Al- alloy/304 stainless steel (Al/SS) was studied in ethylene glycol- water solutions by means of electrochemical methods. Then the localized corrosion morphology of 3A21 alloy, which was the anode in the two galvanic couples, was examined by scanning electron microscope (SEM). The results showed that the average galvanic current densities (Ig) of the two couples Al/Cu and Al/SS decreased with the increasing ethylene glycol concentration, but increased with the rising temperature and ratio of cathode- to- anode area. Although the galvanic couples of Al/Cu and Al/SS exhibited similar corrosion behavior, the ig of galvanic couple Al/Cu was greater than that of the couple Al/SS under the same test condition.
Subjects: Materials Science >> Materials Science (General) submitted time 2023-03-31 Cooperative journals: 《材料研究学报》
Abstract： Nano-flake barium phosphate was prepared by hydrothermal synthesis, and then the effect of which as pigment on the corrosion behavior of epoxy coating was investigated by means of electrochemical impedance spectroscopy (EIS) and salt spray tests. The results show that the nano-flake barium phosphate in the epoxy coating can react with iron oxide, the corrosion product of metal substraste, to generate an insoluble FePO4 as a barrier on the corrosion spot, thereby to enhance the corrosion resistance of the coating; Among others, an epoxy coating with 5 mass% nano flake barium phosphate shows the highest corrosion resistance.
Subjects: Other Disciplines >> Synthetic discipline submitted time 2023-03-28 Cooperative journals: 《中国科学院院刊》
Abstract： Research on spatial pattern and green development of the Yangtze River Economic Belt is of a great significance to promoting ecological civilization construction and regional coordinated development in China. Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences (CAS), has long been focusing on the research of sustainable development in Yangtze River Basin and Southeast Coastal Regions. Since the 1980s, a large number of studies have been conducted on the construction of the Yangtze River Industrial Belt, human activities and its eco-environmental impacts in Yangtze River Basin, shipping and port layout of Yangtze River Golden Waterway, evaluation and utilization of shoreline resources, and governance of space function partition and regional coordinated development. Meanwhile, policy-making and planning consultation as a social service has been afford for different levels of local governments alongside the Yangtze River Economic Belt. These works provide a scientific reference for the Yangtze River Economic Belt development issues in different periods, such as industrial transformation, transportation and shipping construction, ecological and environmental protection, regional division and cooperation, etc.
Subjects: Agriculture, Forestry,Livestock & Aquatic Products Science >> Other Disciplines of Agriculture, Forestry,Livestock & Aquatic Products Science submitted time 2023-02-17 Cooperative journals: 《智慧农业（中英文）》
Abstract： Plant income insurance has become an important part of agricultural insurance in China. It has been recommended to pilot since 2016 by Chinese government in several counties, and is now (2022) required to be implemented in all major grain producing counties in the 13 major grain producing provinces. The measurement of yield for plant income insurance in such huge volume urgently needs the support of remote sensing technology. Therefore, the development history and application status of remote sensing technology in the whole agricultural insurance industry was reviewed to help understanding the whole context circumstances of plant income insurance firstly. Then, the application scenarios of remote sensing technology were analyzed, and the key remote sensing technologies involved were introduced. The technologies involved include crop field plot extraction, crop classification, crop disaster estimation, and crop yield estimation. Research progress of these technologies were reviewed and summarized ,and the satellite data sources that most commonly used in plant income insurance were summarized as well. It was found that to obtain a better support for a development of plant income insurance as well as all crop insurance from remote sensing communities, issues existed not only in the involved remote sensing technologies, but also in the remote sensing industry as well as the insurance industry. The most two important technical problems in the current application scenario of planting income insurance are that: the plot extraction and crop classification are not automated enough; the yield estimation mechanism is not strong, and the accuracy is not high. At the industry level, the first issue is the limitation of the remote sensing technology itself in that the remote sensing is not almighty, suffering from limited data source, either from satellite or from other platform, laborious data preprocessing, and pricey data fees for most of the data, and the second is the compatibility between the current business of the insurance industry and the combination of remote sensing. In this regard, this paper proposed in total five specific suggestions, which are: 1st, to establish a data distribution platform to solve the problems of difficult data acquisition and processing and standardization of initial data; 2nd, to improve the sample database to promote the automation of plot extraction and crop classification; 3rd, to achieve faster, more accurate and more scientific yields through multidisciplinary research; 4th, to standardize remote sensing technology application in agricultural insurance, and 5th, to write remote sensing applications in crop insurance contract. With these improvements, the application mode of plant income insurance and probably the whole agriculture insurance would run in a way with easily available data, more automated and intelligent technology, standards to follow, and contract endorsements.
Subjects: Medicine, Pharmacy >> Clinical Medicine submitted time 2022-11-23 Cooperative journals: 《中国全科医学》
Abstract：
This paper aimed to help beginners to case study in general practice and primary healthcare clarify standard operating procedures for case study, understanding that the "rigor" of case study stems from strict adherence to standard implementation procedures. First, this paper sorted out the development process of case study via literature review, and summarized the connotation, historical background and applicable issues of case study. Then the standard operating procedures of case study were described step by step, and the application of case study in general practice and primary healthcare was illustrated with specific examples. It consists of the following six steps. Step 1: Plan start, determining whether to conduct a case study. Step 2: Plan design, selecting appropriate cases (s) and case study types. Step 3: Job preparation, training and pilot research. Step 4: Data collection, obtaining data from multiple sources. Step 5: Data analysis, drawing conclusions based on evidence. Step 6: Report writing, for the reader. Case study is suitable for solving the questions about "What", "How" and "Why" contained in general practice and primary healthcare, possessing a broad application prospect.
Subjects: Computer Science >> Integration Theory of Computer Science submitted time 2018-04-17 Cooperative journals: 《计算机应用研究》
Abstract： To deal with the problem that classical spectral clustering algorithms are unable to determine the number of clusters automatically, and low efficiency in processing large amount of data with. This paper proposes a spectral clustering algorithm based on the optimization of density peak value. The method firstly calculates the local density of data object and the minimum distance between each data object and other data objects. Adaptive clustering algorithm is generated to determine the number of clusters and to optimize the number of clusters according to certain rules. Secondly, adopting Nystr鰉 sampling can reduce the time complexity of characteristic decomposition and improve the efficiency of the algorithm. The experimental results show that this method can accurately obtain the number of clusters and effectively improve the accuracy and efficiency of clustering effectively.
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