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Hybrid Method by Integrating Deep Reinforcement Learning and Heuristics Approach for Capacitated Vehicle Routing Problem
No full text2022 Innovations in Intelligent Systems and Applications Conference, ASYU 2022 -- 7 September 2022 through 9 September 2022 -- 183936With the spread of online platforms, problems such as manned/unmanned food delivery, cargo delivery, raw material delivery, are increasing the importance of logistics day by day. Vehicle routing problem, which is one of the most important problems in the field of logistics, is a combinatorial problem and as the problem space grows, it takes a long time to find a solution with human effort and in most cases it is not even possible. Thus, it becomes essential for the solution of this problem to be autonomous. Although it is possible to solve the problem with classical heuristic optimization methods, it takes a long time and sometimes does not give a good enough solution. Deep reinforcement learning models with attention mechanisms have great potential in this regard. However,in case of insufficient training in large problem space, it is possible to get away from the optimal solution. In this study, better results are taken in an acceptable time by using the deep reinforcement learning models with attention-model and heuristic methods in a hybrid way. © 2022 IEEE
Tio2 /G-c3 N4 Composite Electrodes for All-Solidstate Supercapacitor Applications
No full textResearch on supercapacitors has recently shifted its attention to the development of low-cost electrode materials with long-cycle stability. It has been thought that titanium dioxide, an important semiconductor material with strong chemical stability and a low cost, is a potential material for capacitors1 . During charging and discharging processes, TiO2 frequently exhibits poor electrical conductivity and agglomeration2 . The overall strategy is to combine conductive carbon-based materials to create hybrid materials to improve their performance3 . g-C3 N4 is a stable allotrope of C3 N4 and it has been gaining more attention for some time. This material is a good alternative for building hybrid systems, and it has optical, electrical, and structural properties that make it a multi-functional material4 and enhances the performance of supercapacitors5 . TiO2 /C3 N4 hybrid material created in this study using an effective, inexpensive, and simple thermal process and utilized as supercapacitor electrodes by using aqueous LiCl/PVA electrolyte. Supercapacitor has shown specific capacitance, power density, and Coulombic efficiency as high as 20.6F.g1, 63Wh.kg-1 and 92% respectively. TiO2 /C3 N4 hybrid materials outperform TiO2 in terms of electrochemical performance
Trump Dönemi Amerikan Güvenlik Politikasında Nato'nun Araçsallaştırılması
No full textIn this master's thesis, the use of NATO as an instrument in the US security policy during the Trump Presidency era, within the scope of the relationship between the USA and NATO, is examined in the context of Neoclassical Realism. The priorities and objectives of the US security policy and the policies of NATO have been analyzed. In this context, the US National Security Strategy Document published in 2017 and the NATO 2030 Report published in 2020 were compared, and the similarities between the two policy documents were revealed. The hypothesis of this study is the view that NATO was used as an instrument in US security policy in terms of military, political and economic aspects during the Trump Era. Based on the main policy issues mentioned in the 2017 US National Security Strategy Document and NATO 2030 Report, the study's primary research question determined how NATO was used as a military, political and economic instrument in the US security policy during the Trump Era. This thesis used case study and process-tracing methods from qualitative research methods, and the two documents were analyzed by comparison. As a result, it has been found that the USA uses NATO as an instrument in its foreign policy and directly affects NATO. On the other hand, it has been seen that NATO desires to collaborate by adopting similar policies with the USA.Bu yüksek lisans tezinde, ABD ve NATO arasındaki ilişki kapsamında, Trump döneminde ABD güvenlik politikasında NATO'nun bir araç olarak kullanılması, Neoklasik Realizm bağlamında incelenmektedir. ABD güvenlik politikasının öncelikleri ve amaçları ile NATO'nun politikaları tahlil edilmiştir. Bu bağlamda, 2017 yılında yayınlanan ABD Ulusal Güvenlik Strateji Belgesi ile 2020 yılında yayınlanan NATO 2030 Raporu karşılaştırılmış ve iki politika belgesi arasındaki benzerlikler ortaya konmuştur. "NATO, Trump Döneminde askeri, siyasi ve ekonomik açıdan Amerikan güvenlik politikasında bir araç olarak kullanılmıştır." görüşü hipotezi oluşturmaktadır. "2017 ABD Ulusal Güvenlik Strateji Belgesi ve NATO 2030 Raporu belgelerinde yer alan temel politika konularından hareketle, Trump Dönemi ABD güvenlik politikasında NATO, askeri, siyasi ve ekonomik açıdan bir araç olarak nasıl kullanılmıştır?" sorusu temel araştırma sorusu olarak belirlenmiştir. Bu tezde, nitel araştırma yöntemlerinden vaka analizi ve süreç takibi yöntemleri kullanılmış ve söz konusu iki belge karşılaştırılarak analiz edilmiştir. Bunun sonucunda, ABD'nin dış politika sürecinde NATO'yu bir araç olarak kullandığı ve NATO'yu doğrudan etkilediği belirlenmiştir. Öte yandan NATO'nun da ABD ile benzer politikalar benimseyerek ortak hareket etme arzusu içinde olduğu anlaşılmıştır
Combining Genetic Algorithm Based Joint Time-Frequency Analysis and Keystone Transform for Isar Image Enhancement
No full textAirbus;Globes;Hensoldt14th European Conference on Synthetic Aperture Radar, EUSAR 2022 -- 25 July 2022 through 27 July 2022 -- 184506Translational and rotational motion of maneuvering targets can cause range and cross-range cell migrations, culminating in a highly smeared final inverse synthetic aperture radar (ISAR) picture. To overcome this problem, a method for ISAR high-resolution imaging and motion compensation (MOCOMP) is proposed that combines adaptive joint timefrequency (AJTF) analysis and keystone transform (KT) based on genetic algorithm (GA). In synthetic data processing, the motion characteristics of the target are estimated using the Matching Pursuit (MP) technique with a third-order model of polynomial function. The Gabor-wavelet transform (GWT) is utilized as a JTF tool to generate a corresponding 3D time-range-Doppler cube. Keystone transform as remapping of the time axis is applied and Translational Motion Compensation (TMC), Rotational Motion Compensation (RMC), and KT have all been proved to operate well together. In raw data processing, the high-resolution image is obtained by using an AJTF and KT based on a genetic algorithm sans MP and GWT to compensate for migrations in the range and Doppler axis. © 2022 Institute of Electrical and Electronics Engineers Inc.. All rights reserved
Pairs Trading: Is It Applicable To Exchange-Traded Funds?
No full textAmong the various statistical trading strategies, pairs trading has been widely employed as a market neutral strategy owing to its simple approach and ease of application. In this context, we develop a cointegration-based pairs trading framework with a set of pre-conditions for pair eligibility and apply it to different asset classes. The performance analysis of a portfolio of 45 pairs is considered for the period of January 2007 to January 2021, which covers the period of a full market cycle of adjacent bull and bear periods; it is studied and benchmarked against the S;P500 index, which is considered as a proxy for the general market. We find an average annual return of 15% with an average Sharpe ratio of 1.43 after considering the transaction costs; we observe that this performance does not vary significantly with a change in the transaction cost levels and does not pass below the risk-free return levels with changing market conditions. Further, the strategy is observed to perform better during bear market conditions. Considering the highly liquid trading environment of the strategy, our findings raise a call for a discussion on the semi-strong form market efficiency. © 2021 The AuthorsThis work was supported by the Scientific and Technological Research Council of Turkey (TÜBİTAK) .Türkiye Bilimsel ve Teknolojik Araştirma Kurumu, TÜBITA
Distributed Sentiment Analysis for Geo-Tagged Twitter Data
No full text30th Signal Processing and Communications Applications Conference, SIU 2022 -- 15 May 2022 through 18 May 2022 -- -- 182415The ever-increasing frequency of sharing on social media makes these platforms one of the primary sources of data for computational social science studies. Similarly, examining and analyzing large scale social media data-sets is crucial for governments as well as companies. However, as the amount of data increases, insights that need to be derived from the data using artificial intelligence based models becomes more and more demanding in terms of processing power. In fact, hardware requirements might dramatically increase if the insights are needed under real-time or near-real time constraints. In this study, we developed a distributed sentiment analysis model that utilizes a large social media data-set. 16 million tweets have been collected and grouped by the originating city. The sentiment analysis model was produced by fine-tuning the pre-trained BERT model. Distributed big data analytics engine, Apache Spark, is used to execute the trained model in a distributed fashion. For evaluation purposes, the prediction time on a single compute unit is compared with the distributed prediction time. Sentiment analysis model has been executed separately for each of the data-groups corresponding to 81 provinces. The data-set containing 16 million tweets used in this study, the Turkish sentiment analysis model produced, the distributed prediction code developed for Apache Spark and all the results of the study can be accessed from the address https://distributed-sentiment-analysis.github.io/. © 2022 IEEE
The Backstages of Archives: the Reverse of Photographs
No full textPhotographs in the archive are believed to hold significance because of the information on their obverse. This article rather focuses upon the reverse of photographic materials as a critical tool to look at the archive. To be more specific, it considers the reverse of the images of Ataturk in the collections of the Turkish Historical Society and deals with the traces there, which serve to assess the content of the images in various ways. As the traces on the reverse of these items are relative to their obverse, the article turns to Erving Goffman's concept of 'backstage' in order to understand the thought-landscape of the archive when it comes to handling visual materials as records
Design and Numerical Analysis of Locally-Resonant Meta-Lattice Structure for Vibration Attenuation
No full textASME International Mechanical Engineering Congress and Exposition (IMECE) -- OCT 30-NOV 03 -- 2022 -- Columbus -- OHMeta-materials are artificial materials that perform superior properties in addition to natural behavior. Regardless of their chemical properties, metamaterials show high performance due to their geometric orientation. There are mechanical metamaterials that are used in vibration and acoustic fields, the main subject of which is wave transmission. The propagation of mechanical waves, which can cause problems such as structural damage, fatigue, poor performance, and discomfort in the industry, can be prevented or reduced by using meta-materials. Mechanical waves of various frequencies can be reduced or eliminated by locally resonant metamaterials obtained by adding various masses to viscoelastic materials. Metamaterials can be designed by modifying various lattice structures. Higher performance metamaterials are designed in this study by modifying the lattice structures used in the literature for vibration isolation. Finite element analyzes are carried out to show the transmissibility performance of the designed meta-lattice structures.Amer Soc Mech Engineer