In order to study the acoustic performance of underwater vehicle including vibration and noise, two kinds of structure models of an underwater craft cabin in the air medium and in the water medium were analyzed separa...
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In order to study the acoustic performance of underwater vehicle including vibration and noise, two kinds of structure models of an underwater craft cabin in the air medium and in the water medium were analyzed separately by finite element method. Through modal analysis,the impedance ratios of the two kinds of models were calculated. The influence of the thickness of the pressure hull on the impedance ratio of the structure was studied, and the acoustic transfer performance was analyzed and compared between the two kinds of models.
As an important facility for acoustic measurement and research in air medium, anechoic wind tunnel requires high acoustic performance. In this paper, the flow field and acoustic characteristics of anechoic wind tunnel...
As an important facility for acoustic measurement and research in air medium, anechoic wind tunnel requires high acoustic performance. In this paper, the flow field and acoustic characteristics of anechoic wind tunnel were studied by modeling and simulation. The velocity and pressure distribution of the whole flow field in the wind tunnel are obtained by simulation calculation, and the noise source distribution in the anechoic wind tunnel is studied by the broadband noise source method, which provides a reference for the design, construction and optimization of the anechoic wind tunnel.
In order to study the acoustic performance of underwater vehicle including vibration and noise, two kinds of structure models of an underwater craft cabin in the air medium and in the water medium were analyzed separa...
In order to study the acoustic performance of underwater vehicle including vibration and noise, two kinds of structure models of an underwater craft cabin in the air medium and in the water medium were analyzed separately by finite element method. Through modal analysis, the impedance ratios of the two kinds of models were calculated. The influence of the thickness of the pressure hull on the impedance ratio of the structure was studied, and the acoustic transfer performance was analyzed and compared between the two kinds of models.
In response to the centralized single-architecture abnormal traffic detection method in Software Defined Network (SDN), which consumes massive computational and network resources, and may lead to the decline of servic...
In response to the centralized single-architecture abnormal traffic detection method in Software Defined Network (SDN), which consumes massive computational and network resources, and may lead to the decline of service quality of SDN network, this paper proposes a large-scale abnormal traffic detection method of SDN network based on Distributed Convolutional Neural Networks and Gate Recurrent Unit (DCNN-GRU) architecture. This method utilizes lightweight detection agents based on CNN deployed on each controller to extract traffic features preliminarily. Then it inputs the feature data into the GRU-based deep detection model hosted in the cloud for collaborative training and completes the final abnormal detection task. Since the feature extraction tasks are distributed across multiple controllers, the cloud server only needs to relearn and classify the extracted feature data, which is less costly than directly extracting feature information from the original traffic data and occupies less bandwidth resources than transmitting complete data packets. The experiment shows that the method achieves an abnormal detection accuracy of 0.9939, a recall rate of 0.9831, and a false alarm rate of only 0.0244, obtaining a higher precision and lower false alarm rate than traditional detection methods.
In recent years, providing the required criteria put forward for the full membership by the union is one of the prior targets of Turkey in the European Union full membership process. The objective of this study is to ...
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In recent years, providing the required criteria put forward for the full membership by the union is one of the prior targets of Turkey in the European Union full membership process. The objective of this study is to be able to evaluate situations of the membership process among European countries, candidate countries and Turkey. In the data set used in the period of 2005-2010, it is seen that the global economic crisis becoming efficient towards the end of 2007 has affected both EU countries and candidate countries economically. This period which included the effect of global crisis was taken as a data set to the study in order to add the effect of global crisis into the evaluation. The study was tried to be analyzed by using artificial neural networks and decision trees algorithms by means of a variety of economic signs. For that purpose, the data between years of 2005-2010 were used in this study. Primarily, the relative importance of independent variables was found by means of multilayered artificial neural networks and then dimension reduction operation was done. The criteria thought as affecting the membership was tried to be found out by using the decision trees method.
In recent years, there has been a fierce competition in the telecommunication sector. Technologic competition has made the competition in the sector a kind of strategic war. The sector of which role increased in terms...
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In recent years, there has been a fierce competition in the telecommunication sector. Technologic competition has made the competition in the sector a kind of strategic war. The sector of which role increased in terms of economic developments has entered a reconstruction process at an equal rate in all countries. In fact, countries which apprehend the future of the sector will also determine the future of economy. In this respect the aim of this study is to make performance benchmarking by using Data Envelopment Analysis and Malmquist Total Factor Productivity Index on telecommunication sector which is thought as one of the most important signs of national economies in the global economic crisis environment. This benchmarking, which includes the period of global crisis between the years of 2007-2010, targets to measure to what extent countries have been affected from the global crisis environment by means of performance evaluation among the strongest telecom managements of countries such as Turkey and Group of Eight (G8) countries? In the study, annual activity reports of the managements and a variety of input and output variables acquired from various research institutions were used as a data set.
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