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Aiming at the blade flutter of large horizontal-axis wind turbines, a method by utilizing biomimetic corrugation to suppress blade flutter is first proposed. By extracting the dragonfly wing corrugation, the biomimetic corrugation airfoil is constructed, finding that mapping corrugation to the airfoil pressure side has better aerodynamic performance. The influence of corrugation type, amplitudeλ, and intensity on airfoil flutter is analyzed using orthogonal experiment, which determines that theλhas the greatest influence on airfoil flutter. Based on the fluctuation range of the moment coefficient ΔCm, the optimal airfoil flutter suppression effect is obtained when the type is III,λ= 0.6, and intensity is denser (n= 13). The effective corrugation layout area in the chord direction is determined to be the leading edge, and the ΔCmof corrugation airfoil is reduced by 7.405%, compared to the original airfoil. The application of this corrugation to NREL 15 MW wind turbine 3D blades is studied, and the influence of corrugation layout length in the blade span direction on the suppressive effect is analyzed by fluid-structure interaction. It is found that when the layout length is 0.85 R, the safety marginSfreaches a maximum value of 0.3431 Hz, which is increased 2.940%. The results show that the biomimetic corrugated structure proposed in this paper can not only improve the aerodynamic performance by changing the local flow field on the surface of the blade, but also increase the structural stiffness of the blade itself, and achieve the effect of flutter suppression.
Assuntos
Biomimética , Desenho de Equipamento , Vento , Asas de Animais , Animais , Asas de Animais/fisiologia , Biomimética/métodos , Odonatos/fisiologia , Materiais Biomiméticos/química , Voo Animal/fisiologia , Centrais ElétricasRESUMO
Digital online application is a commonly used method for professional title evaluation in colleges and universities. With the rapid development of the mobile Internet of Things, the fastest way for users to access the evaluation system is through mobile devices. However, this also poses security challenges to the traditional professional title evaluation system. Therefore, this paper proposes a decentralized and security-enhanced digital title evaluation system in mobile IoT. Since the system uses blockchain to implement a decentralized review process, the transparency and fairness of the review process are guaranteed. At the same time, the review data and reviewer information in the system are encrypted and stored in the distributed network to ensure the security and non-tamperability of the data. All review records are recorded on the blockchain, and anyone can view and verify the legitimacy of the review results. Additionally, the system incorporates security enhancement mechanisms such as identity verification, smart contracts, and auditing functions to improve the credibility of the evaluation process and prevent cheating under mobile IoT. Experiments have shown that this system has important application value in the field of professional title review in universities, which can improve review efficiency, reduce human intervention, and provide strong support for the credibility of review results.
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The Internet of Things (IOT) is based on the computer Internet, using RFID, wireless data communication and other technologies to construct a network covering everything in the world. It contains numerous entities such as sensors, processors, transmitters and actuators, meanwhile the interactions of which are complicated. These characteristics of IOT are consistent with those of the complex network. Motivated by this, this paper comprehends the security issue of IOT from the sight of the observability of complex network and regards the ability of reconstruction as a security threat to IOT network. We try to identify the minimum vertices whose data could reconstruct the whole data of network, in other words, we need to implement additional protective measures on these vertices to enhance the security of IOT network. By analyzing the topology of IOT network, an identification strategy is adopted and the corresponding algorithm is proposed to identify the minimum protection vertices.
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The Internet of Things (IoT) connects devices, enabling real-time data acquisition, automation, and collaboration. Wireless sensor networks are one of the important components of the Internet of Things, consisting of many wireless sensor nodes distributed in space. These nodes can perceive environmental information and transmit it to other nodes through wireless communication. In wireless sensor network routing optimization methods, improved ant colony algorithm can be used to find the optimal routing scheme. Ant colony algorithm simulates the behavior of ants in the process of searching for food, and optimizes factors such as transfer probability and pheromone concentration to enable ants to find the shortest path. In wireless sensor networks, node positions can be used as reference nodes and anchor nodes, combined with the objective function of wireless sensor network routing optimization, and improved ant colony algorithm can be used to solve the optimal path, thus obtaining the optimal wireless sensor network routing optimization scheme. Through experimental results, it can be found that the proposed method performs well in terms of energy consumption, transmission delay, number of dead nodes, and network throughput. These optimization results have positive implications for the sustainable development and practical application of the Internet of Things, which can improve the development of the digital economy and enhance the construction of smart cities.
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The severity of mental health issues among college students has increased over the past few years, having a significant negative impact on not only their academic performance but also on their families and even society as a whole. Therefore, one of the pressing issues facing college administrators right now is finding a method that is both scientific and useful for determining the mental health of college students. In pace with the advancement of Internet technology, the Internet has become an important communication channel for contemporary college students. As one of the main forces in the huge Internet population, college students are at the stage of growing knowledge and being most enthusiastic about new things, and they like to express their opinions and views on study life and social issues and are brave to express their emotions. These subjective text data often contain some affective tendencies and psychological characteristics of college students, and it is beneficial to dig out their affective tendencies to further understand what they think and expect and to grasp their mental health as early as possible. In order to address the issue of assessing the mental health of college students, this study makes an effort to use public opinion data from the university network and suggests a college student sentiment analysis model based on the OCC affective cognitive model and Bi-LSTM neural network. In order to label three different types of positive, negative, and neutral sentiment on the microblog text of college network public opinion, we first design a sentiment rule system based on the OCC affective cognition elicitation mechanism. In order to effectively and automatically identify the sentiment state of college students in the network public opinion, this study uses a Bi-LSTM neural network to classify the preprocessed college network public opinion data. Finally, this study performs comparison experiments to confirm the validity of the Bi-LSTM neural network sentiment recognition algorithm and the accuracy of the OCC sentiment rule labeling system. The findings show that the college student sentiment recognition effect of the model is significantly enhanced when the OCC sentiment rule system is used to label the college network public opinion data set as opposed to the naturally labeled data set. In contrast to SVM and other classification models like CNN and LSTM, the Bi-LSTM neural network-based classification model achieves more satisfactory classification results in the recognition of college opinion sentiment.
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Algoritmos , Redes Neurais de Computação , Cognição , Emoções , Humanos , Opinião PúblicaRESUMO
Mukonal is an active member of carbazole alkaloids isolated from Murraya koenigii. It has been shown to possess remarkable biological and pharmacological activities including anticancer activity. Therefore, the aim of current investigation was to explore anti-breast cancer activity of mukonal and to explore the underlying mechanism. Results indicate that mukonal has potential to induce antiproliferative effects against MDA-MB-231 and SK-BR-3 cells with an IC50 of 7.5 µM. No significant toxicity of mukonal was observed in case of normal breast cells. The antiproliferative effects of mukonal were found to proceed via apoptosis, which was further supported by increased cleavage of PARP and caspase-3 and reduced expression of Bcl-2. Mukonal induced autophagic cells death in breast cancer cells as was evidenced by formation of autophagosomes and enhanced expressions of Beclin-1, LC3B-I and LC3B-II proteins. In vivo examination of anti-breast cancer property of mukonal indicated that it could potentially reduce tumor weight and volume in xenografted mice models. In conclusion, mukonal has a remarkable potential of inhibiting breast cancer via induction of apoptosis and autophagy. Mukonal also inhibited xenografted tumors models in a dose-dependent manner. Therefore, mukonal may prove lead molecule in breast cancer drug discovery and treatment provided further investigations are recommended.