45,522 results on '"Sahin A"'
Search Results
2. Analyzing regression models and multi-layer artificial neural network models for estimating taper and tree volume in Crimean pine forests
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Sahin A
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Compatible Tree Taper ,Merchantable Volume Equations ,Crimean Pine ,Multilayer Artificial Neural Network ,Hyper-parameter Customization ,Forestry ,SD1-669.5 - Abstract
The taper and merchantable tree volume equations are the most used models in forestry because of their accuracy in estimating both total and merchantable tree volume. However, numerous studies reported that artificial neural network models show fewer errors and a greater success rate as compared to regression models. This study used data from 200 Crimean pine trees in Turkey’s Central Anatolia and Mediterranean Region to assess the performance of artificial neural network (ANN) models and the Max-Burkhart’s equation for estimating taper and merchantable tree volume. The most accurate results were obtained using 3 hidden layers and 10 neurons in the taper model and 1 hidden layer and 100 neurons in the volume model. The hyperbolic tangent sigmoid function was used for the ANN analysis and hyper-parameter customization. Using the ANN model with hyper-parameter customization, the AAE in the Max-Burkhart taper model decreased from 9.315 to 6.939 (-25.5%), the RMSE decreased from 3.072 to 2.656 (-13.5%), and the FI increased from 0.964 to 0.966 (+1.23%). Similarly, using the ANN model with hyper-parameter customization, the AAE in the Max-Burkhart volume model decreased from 0.056 to 0.013 (-76.6%), the RMSE decreased from 0.247 to 0.12 (-51.6%), and the FI increased from 0.909 to 0.979 (+7.69%). Our results showed that the ANN models’ predictions were more accurate and reliable compared to the Max-Burkhart’s equations. We resolved overfitting via hyper-parameter modification, which also allowed for monitoring the impact of error and prediction outputs at various learning rates. It was also possible to develop tree taper and volume equations with lower error rates in both training and validation data, consistent with tree growth trends in both data sets.
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- 2024
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3. A Survey on Sensor Selection and Placement for Connected and Automated Mobility
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Mehmet Kiraz, Fikret Sivrikaya, and Sahin Albayrak
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CAVs ,CAM ,ITS ,sensor placement ,sensor selection ,sensor location problem ,Transportation engineering ,TA1001-1280 ,Transportation and communications ,HE1-9990 - Abstract
The progress towards fully autonomous mobility is significantly impacted by the integration of evolving technologies in connected and automated mobility (CAM). Connected and automated vehicles (CAVs) have the potential to revolutionize our transportation system by improving efficiency, safety, and environmental sustainability. Automated shuttles and public buses, smart traffic signals, intelligent passenger cars, and smart roundabouts are just a few examples of technologies that are being planned and actively researched for integration into transportation systems. Sensors are essential in making this possible. This article provides a structured overview of research on the selection and positioning of sensors on- and off-vehicle to achieve cooperative, connected, and automated mobility. The general integration and usage of sensors in vehicles and infrastructure is described, a detailed taxonomy of the examined research is provided, and future research directions are presented, involving solutions for quantification of sensor performance and addressing current trends. The findings of this article also highlight numerous challenges in creating a universal framework, the lack of application of novel machine learning methods, and the complexity of modeling multi-sensor settings.
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- 2024
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4. Probabilistic Risk Assessment in Power Systems With High Wind Energy Penetration
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Mahmoud Draz, Fabian Pagel, and Sahin Albayrak
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Machine learning ,power systems reliability ,power forecasting ,uncertain optimization ,risk assessment ,Electrical engineering. Electronics. Nuclear engineering ,TK1-9971 - Abstract
Power systems are increasingly confronted with operational uncertainties. These stem from the integration of wind and solar energy sources with inherently stochastic generation behavior. The ensuing risks include power plant curtailments or grid imbalances. The deterministic approaches that currently underpin most planning have proven insufficient to manage these risks. This paper presents an alternative in the form of a data-driven probabilistic approach with direct relevance for transmission system operators. The models present a novel methodology that is independent of the common boundary conditions, e.g. case-specific models. First, we compare several data-driven algorithms and assign the forecasting task to the best-performing one. Second, the resulting forecast serves as an input for three optimal power flow (OPF) problems we tailor to the German power system. These problems minimize energy import volumes, energy import costs, and overall power losses. Third, based on the OPF results, we perform a risk assessment for operational instability, power loss, financial losses, and renewable energy waste. The results show that neural networks slightly outperform traditional machine learning algorithms in forecasting accuracy. However, linear-quadratic regulators remain attractive for their simplicity-performance ratio. Our probabilistic OPF approach can reduce power losses and identify frequency and line loading irregularities that deterministic methods do not. The data-driven approach we propose is superior to existing approaches in terms of its performance, usability, and applicability to complex power systems.
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- 2024
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5. An Agent-Based Data Acquisition Pipeline for Image Data
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Benjamin Acar, Martin Berger, Marc Guerreiro Augusto, Tobias Kuster, Fikret Sivrikaya, and Sahin Albayrak
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Data pipelines ,agents ,data processing ,streaming ,autonomous driving ,Electrical engineering. Electronics. Nuclear engineering ,TK1-9971 - Abstract
The efficient processing of information plays a critical role in data-driven domains. Data acquisition pipelines, which act as the interface between data collection and subsequent processing, are central to this. Traditional software engineering methods form the foundation for the development of robust data acquisition pipelines, but agent-based systems hold great potential for realizing such pipelines, and this study presents an innovative architecture that uses agent-based components. This modular approach makes it possible to use specialized agents for individual tasks and to increase the effectiveness of the pipelines. The applicability and effectiveness of this architecture are demonstrated using a system for autonomous driving that collects and processes data from edge computers along roads. Our results are on GitHub (https://github.com/BenjaminAcar/Agent-based-Data-Acquisition-Pipeline).
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- 2024
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6. Driving into the future: a cross-cutting analysis of distributed artificial intelligence, CCAM and the platform economy
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Marc Guerreiro Augusto, Benjamin Acar, Andrea Carolina Soto, Fikret Sivrikaya, and Sahin Albayrak
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Autonomous Mobility ,Cooperative Connected and Automated Mobility ,Distributed Artificial Intelligence ,Intelligent Infrastructure ,Platform Development ,Platform Economy ,Electronic computers. Computer science ,QA75.5-76.95 ,Computer engineering. Computer hardware ,TK7885-7895 - Abstract
Abstract The future of driving is autonomous. It requires a comprehensive stack of embedded software components, enabled by open-source and proprietary platforms at different abstraction layers, and then operating within a larger ecosystem. Autonomous driving demands connectivity, cooperation and automation to form the cornerstone of autonomous mobility solutions. Platform economy principles have revolutionized the way we produce, deliver and consume products and services worldwide. More and more businesses in the field of mobility and transport appear to implement transaction, innovation, and integration platforms as core enablers for Mobility-as-a-Service and transport applications. Artificial intelligence approaches, especially those dealing with distributed systems, enable new mobility solutions, such as autonomous driving. This paper contributes to understanding the intertwining role between distributed artificial intelligence, autonomous mobility and the resulting platform ecosystem. A systematic literature review is applied, in order to identify the intersection between those aspects. Furthermore, the research project BeIntelli is considered as a hands-on application of our findings. Taking into account our analysis and the aforementioned research project, we pose a blueprint architecture for autonomous mobility. This architecture is the subject of further research. Our conclusions facilitate the development and implementation of future urban transportation systems and resulting mobility ecosystems in practice.
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- 2024
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7. Opinerium: Subjective Question Generation Using Large Language Models
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Pedram Babakhani, Andreas Lommatzsch, Torben Brodt, Doreen Sacker, Fikret Sivrikaya, and Sahin Albayrak
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Subjective questions ,LLMs ,Seq2Seq generation ,fine tuning ,zero-shot learning ,Electrical engineering. Electronics. Nuclear engineering ,TK1-9971 - Abstract
This paper presents a comprehensive study on generating subjective inquiries for news media posts to empower public engagement with trending media topics. While previous studies primarily focused on factual and objective questions with explicit or implicit answers in the text, this research concentrates on automatically generating subjective questions to directly elicit personal preference from individuals based on a given text. The research methodology involves the application of fine-tuning techniques across multiple iterations of flan-T5 and GPT3 architectures for the task of Seq2Seq generation. This approach is meticulously evaluated using a custom dataset comprising 40,000 news articles along with human-generated questions. Furthermore, a comparative analysis is conducted using zero-shot prompting via GPT-3.5, juxtaposing the performance of fine-tuned models against a significantly larger language model. The study grapples with the inherent challenges tied to evaluating opinion-based question generation due to its subjective nature and the inherent uncertainty in determining answers. A thorough investigation and comparison of two transformer architectures are undertaken utilizing conventional lexical overlap metrics such as BLEU, ROUGE, and METEOR, alongside semantic similarity metrics encompassing BERTScore, BLEURT, and answerability scores such as QAScore, and RQUGE. The findings underscore the marked superiority of the flan-T5 model over GPT3, substantiated not only by quantitative metrics but also through human evaluations. The paper introduces Opinerium based on the open-source flan-T5-Large model, identified as the pacesetter in generating subjective questions. Additionally, we assessed all aforementioned metrics thoroughly by investigating the pairwise Spearman correlation analysis to identify robust metrics.
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- 2024
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8. OPACA: Toward an Open, Language- and Platform-Independent API for Containerized Agents
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Benjamin Acar, Tobias Kuster, Oskar F. Kupke, Robert K. Strehlow, Marc Guerreiro Augusto, Fikret Sivrikaya, and Sahin Albayrak
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Multi-agent systems ,microservices ,Kubernetes ,Docker ,API ,Electrical engineering. Electronics. Nuclear engineering ,TK1-9971 - Abstract
While multi-agent frameworks can provide many advanced features, they often suffer from not being able to seamlessly interact with the outside world, e.g., with web-services or other multi-agent frameworks. This may be one factor that hinders a broader application of multi-agent systems in production systems. A possible solution to this problem is the combination of multi-agent systems with the concepts of micro-services and containerization, providing language-agnostic open interfaces, as well as encapsulation and modularity. In this paper, we propose an API and reference implementation that can be employed by multi-agent systems based on different languages and frameworks. Each agent component is encapsulated in a container and is accessed through its parent runtime platform, which takes care of aspects such as authentication, input validation, monitoring and other infrastructure tasks. Multiple runtime platforms can then be connected to form systems of distributed, heterogeneous multi-agent societies.
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- 2024
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9. Artificial Intelligence in Biomaterials: A Comprehensive Review
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Yasemin Gokcekuyu, Fatih Ekinci, Mehmet Serdar Guzel, Koray Acici, Sahin Aydin, and Tunc Asuroglu
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artificial intelligence ,machine learning ,deep learning ,biomaterials ,tissue engineering ,material optimization ,Technology ,Engineering (General). Civil engineering (General) ,TA1-2040 ,Biology (General) ,QH301-705.5 ,Physics ,QC1-999 ,Chemistry ,QD1-999 - Abstract
The importance of biomaterials lies in their fundamental roles in medical applications such as tissue engineering, drug delivery, implantable devices, and radiological phantoms, with their interactions with biological systems being critically important. In recent years, advancements in deep learning (DL), artificial intelligence (AI), machine learning (ML), supervised learning (SL), unsupervised learning (UL), and reinforcement learning (RL) have significantly transformed the field of biomaterials. These technologies have introduced new possibilities for the design, optimization, and predictive modeling of biomaterials. This review explores the applications of DL and AI in biomaterial development, emphasizing their roles in optimizing material properties, advancing innovative design processes, and accurately predicting material behaviors. We examine the integration of DL in enhancing the performance and functional attributes of biomaterials, explore AI-driven methodologies for the creation of novel biomaterials, and assess the capabilities of ML in predicting biomaterial responses to various environmental stimuli. Our aim is to elucidate the pivotal contributions of DL, AI, and ML to biomaterials science and their potential to drive the innovation and development of superior biomaterials. It is suggested that future research should further deepen these technologies’ contributions to biomaterials science and explore new application areas.
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- 2024
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10. Socio-economic impact of COVID-19 pandemic on dairy farm households in West Bengal state
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SAHIN AKTAR MUNSHI, ABHIJIT DAS, SHIVASWAMY G P, M C ARUNMOZHI DEVI, S SUBASH, S JEYAKUMAR, and MUNIANDY SIVARAM
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Artificial insemination, Infected and uninfected households, Lockdown, Marketed milk surplus, Milk prices, Milk productivity ,Animal culture ,SF1-1100 - Abstract
India is one of the leading economies that have been stuck hard by the COVID-19 pandemic and the stringent measures were put in place to combat it. Among several sectors, dairy sector is the most affected as dairy products are highly perishable and rely on time-sensitive supply chains. Though studies are available on the impact of COVID-19 pandemic on dairy sector, there are no studies on COVID-infected dairy farm households. The present study was an attempt to assess the socio-economic impact of COVID-19 pandemic on infected and uninfected dairy farm households in West Bengal. The study covered pre-lockdown, lockdown (both 1st and 2nd wave) and post-lockdown phases of COVID-19 pandemic. The primary data was collected from 150 dairy farm households (COVID-19 infected-75 and uninfected-75) in Murshidabad and Nadia districts of West Bengal. Dairy Economic Performance Index consisting of number of milch animals, milk yield, marketed milk, milk procurement price, concentrate price and veterinary cost was developed using principal component analysis. In order to make infected and uninfected groups statistically comparable, propensity score matching technique was employed. The index values were compared between matched infected and uninfected groups over different phases of COVID-19 pandemic. Dairy households incurred significant economic losses during the lockdown and post-lockdown periods due to increase in cost of concentrates, decline in the number of milch animals and drop in milk procurement prices. Dairy households faced constraints in procuring dry fodder, concentrate feed and in accessing veterinary care. COVID-19 infected dairy farm households had a greater socio-economic hurdle than that of uninfected households.
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- 2024
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11. A Nationwide Chronic Disease Management Solution via Clinical Decision Support Services: Software Development and Real-Life Implementation Report
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Mustafa Mahir Ulgu, Gokce Banu Laleci Erturkmen, Mustafa Yuksel, Tuncay Namli, Şenan Postacı, Mert Gencturk, Yildiray Kabak, A Anil Sinaci, Suat Gonul, Asuman Dogac, Zübeyde Özkan Altunay, Banu Ekinci, Sahin Aydin, and Suayip Birinci
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Computer applications to medicine. Medical informatics ,R858-859.7 - Abstract
BackgroundThe increasing population of older adults has led to a rise in the demand for health care services, with chronic diseases being a major burden. Person-centered integrated care is required to address these challenges; hence, the Turkish Ministry of Health has initiated strategies to implement an integrated health care model for chronic disease management. We aim to present the design, development, nationwide implementation, and initial performance results of the national Disease Management Platform (DMP). ObjectiveThis paper’s objective is to present the design decisions taken and technical solutions provided to ensure successful nationwide implementation by addressing several challenges, including interoperability with existing IT systems, integration with clinical workflow, enabling transition of care, ease of use by health care professionals, scalability, high performance, and adaptability. MethodsThe DMP is implemented as an integrated care solution that heavily uses clinical decision support services to coordinate effective screening and management of chronic diseases in adherence to evidence-based clinical guidelines and, hence, to increase the quality of health care delivery. The DMP is designed and implemented to be easily integrated with the existing regional and national health IT systems via conformance to international health IT standards, such as Health Level Seven Fast Healthcare Interoperability Resources. A repeatable cocreation strategy has been used to design and develop new disease modules to ensure extensibility while ensuring ease of use and seamless integration into the regular clinical workflow during patient encounters. The DMP is horizontally scalable in case of high load to ensure high performance. ResultsAs of September 2023, the DMP has been used by 25,568 health professionals to perform 73,715,269 encounters for 16,058,904 unique citizens. It has been used to screen and monitor chronic diseases such as obesity, cardiovascular risk, diabetes, and hypertension, resulting in the diagnosis of 3,545,573 patients with obesity, 534,423 patients with high cardiovascular risk, 490,346 patients with diabetes, and 144,768 patients with hypertension. ConclusionsIt has been demonstrated that the platform can scale horizontally and efficiently provides services to thousands of family medicine practitioners without performance problems. The system seamlessly interoperates with existing health IT solutions and runs as a part of the clinical workflow of physicians at the point of care. By automatically accessing and processing patient data from various sources to provide personalized care plan guidance, it maximizes the effect of evidence-based decision support services by seamless integration with point-of-care electronic health record systems. As the system is built on international code systems and standards, adaptation and deployment to additional regional and national settings become easily possible. The nationwide DMP as an integrated care solution has been operational since January 2020, coordinating effective screening and management of chronic diseases in adherence to evidence-based clinical guidelines.
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- 2024
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12. A Survey on the Use of Container Technologies in Autonomous Driving and the Case of BeIntelli
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Benjamin Acar, Marc Guerreiro Augusto, Marius Sterling, Fikret Sivrikaya, and Sahin Albayrak
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Docker ,containerization ,automotive ,CCAM ,autonomous driving ,Transportation engineering ,TA1001-1280 ,Transportation and communications ,HE1-9990 - Abstract
The application of containerization technology has seen a significant increase in popularity in recent years, both in the business and scientific sectors. In particular, the ability to create portable applications that can be deployed on different machines has become a valuable asset. Autonomous driving has embraced this technology, as it offers a wide range of potential applications, including the operation of autonomous vehicles and the digitization of infrastructure for the development of Cooperative, Connected, and Automated Mobility (CCAM) services. This paper provides a comprehensive analysis of containerization in autonomous driving, emphasizing its application, utility, benefits, and limitations.
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- 2023
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13. Optimal Location and Sizing of Electric Bus Battery Swapping Station in Microgrid Systems by Considering Revenue Maximization
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Mustafa Cagatay Kocer, Ahmet Onen, Jaesung Jung, Hakan Gultekin, and Sahin Albayrak
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Ancillary services ,battery swapping station ,electric bus ,electric vehicle ,microgrid ,optimal location ,Electrical engineering. Electronics. Nuclear engineering ,TK1-9971 - Abstract
The radical increase in the popularity of electric vehicles (EVs) has in turn increased the number of associated problems. Long waiting times at charging stations are a major barrier to the widespread adoption of EVs. Therefore, battery swapping stations (BSSs) are an efficient solution that considers short waiting times and healthy recharging cycles for battery systems. Moreover, swapping stations have emerged as a great opportunity not only for EVs, but also for power systems, with regulation services that can be provided to the grid particularly for small networks, such as microgrid (MG) systems. In this study, the optimum location and size that maximize the revenue of a swap station in an MG system are investigated. To the best of our knowledge, this study is first to solve the placing and sizing problem in the MG from the perspective of a BSS. The results indicate that bus 23 is the BSS’s optimal location and is crucial for maximizing revenue and addressing issues like the provision of ancillary services in microgrid system. Finally, the swap demand profile of the station serving electric bus public transportation system was obtained using an analytical model based on public transportation data collected in Berlin, Germany.
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- 2023
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14. Elementary Teachers' Self-Efficacy and Its Role in STEM Implementation
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Caroline Buechel, Michael K. Daugherty, Vinson Carter, and Emine Sahin Topalcengiz
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To equip students with 21st-century skills, teachers must have both deep STEM content knowledge and the confidence to implement and teach appropriate STEM content. Many elementary teachers have inadequate STEM background knowledge, low confidence, and STEM self-efficacy for implementing STEM in the classroom; as a result, teachers' classroom practices are affected. The study examined how elementary teachers perceive their ability to implement STEM in the classroom. The STEM Efficacy Survey was sent to a randomized pool of 100 elementary educators, and 18 of them agreed to participate in the study. This instrument was designed to elicit responses related to the teachers' previous background in STEM, their beliefs about their ability to implement STEM, and their actual STEM implementation in the elementary classroom. The results revealed that participants were confident in their understanding of the engineering design process and problem-based learning. However, teachers were unwilling to apply the engineering design process in the classroom. From this research, the researchers concluded that higher levels of training in STEM education may influence how teachers perceive their ability to implement STEM in the classroom. Further research should focus on exploring how STEM training affects teachers' self-efficacy in STEM implementation.
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- 2024
15. Mapping the Research Agenda in Virtual Reality Studies within Education
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Ezgi Dogan and Ferhan Sahin
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This systematic literature review (SLR) scrutinizes the trends and interrelationships prevalent in Virtual Reality (VR) applications within educational frameworks, analyzing a comprehensive pool of 43 theses conducted in a Eurasian country. The primary objectives encompass investigating learning-teaching theories, learning domains, design elements, VR typology, and the departments undertaking VR research. Findings from the SLR underscore a significant concentration of VR research activities within technology-oriented departments. The prevalent approach involves experimental assessments of diverse variables within VR learning environments, yet a conspicuous dearth of design-centric investigations is observed. This highlights a critical need for comprehensive studies elucidating the design and developmental processes within VR applications, especially in light of the current characterization of VR research as lacking established standards. Moreover, a noteworthy revelation is the prevalent absence of a robust theoretical framework across the majority of studies. This absence may pose impediments to the widespread adoption of VR within educational paradigms, given the pivotal role of learning-teaching theories in guiding pedagogical processes. Examination of design elements highlights the prominence of realistic experiences, passive observation, mobility, and interaction with the environment. Recognizing the potential impact of diverse design elements on enhancing realism, aligning specific elements with distinct learning domains holds promise for augmenting the immersive quality of VR experiences. This research emphasizes the critical need for more comprehensive, theory-guided, and design-focused VR studies to propel its integration effectively within educational landscapes.
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- 2024
16. Roadmap for Equality in Education: Problems, Solutions and Implementation Strategies
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Kürsat Sahin Yildirimer
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Equality in education is a fundamental goal for societies, and educational systems need to provide equal opportunities for all individuals to realize their potential. However, in the current situation, economic, social and cultural differences create inequality of opportunity in education and this is a fundamental problem of education systems. This article emphasizes the importance of achieving the goal of equality in education and discusses the problems encountered in achieving this goal. By examining the root causes and consequences of inequalities in education, it aims to better understand these problems. Furthermore, the article presents key strategies for achieving equity in education. These strategies include reviewing education policies, training and supporting teachers, increasing access to education for disadvantaged groups, using technology-based education methods and developing antidiscrimination awareness programs. In this context, the goal of achieving equity in education is critical for social development and human rights, and the paper aims to provide a roadmap for equity in education, presenting the steps and strategies needed to achieve this important goal.
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- 2024
17. An Evaluation of the Spatial Repercussions of Student Mobility Policy in European Higher Education Area Using Network Analysis
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Savas Zafer Sahin, Betül Bulut Sahin, and Emrah Söylemez
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The mobility of international students is a crucial tool for the European Union's goal of creating a unified European Higher Education Area. Despite the initial assumption that all European universities and students can benefit equally from cross-university study experiences, certain European regions have become disproportionately favored over time. This has resulted in specific geographical patterns, challenging the principles of equality and openness in the EU's higher education policy. To better understand these spatial effects and enhance the EU's mobility policy effectiveness, this research analyzes the network properties of Erasmus+, comparing it with traditional degree-seeking activities. Utilizing a modularity measure with data from the EU and UNESCO, the study reveals significant sub-regional variations in the Erasmus+ geographical network, posing challenges for policy implementation and limiting mobility alternatives.
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- 2024
18. Theoretical Investigation of Viscosity and Thermal Conductivity of a Gas along a Non-isothermal Vertical Surface in Porous Environment with Dissipative Heat: Numerical Technique
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Silpi Hazarika and Sahin Ahmed
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dissipative heat ,fluid viscosity and thermal conductivity ,soret effect ,thermal radiation ,magnetic drag force method ,Mechanics of engineering. Applied mechanics ,TA349-359 - Abstract
The prime objective of the current investigation is to explore the variation of viscosity and thermal conductivity impacts on MHD convective flow over a moving non-isothermal vertical plate in presence of the viscous-dissipative heat and thermal-radiation. The compatible transformation of similarity are employed to obtain the non-linear ODE with the appropriate boundary conditions from the governing equations and the numerical solution of the boundary value problem so obtained are solved via MATLAB bvp4c solver. Naturally, the fluid viscosity and thermal-conductivity may vary from liquid to metal with temperatures and therefore, the impact of viscosity and thermal-conductivity in this investigation is quite significant. The physical parameters along with several influences on momentum, temperature, and concentration are explicated and portrayed with graphs. In addition, the velocity, temperature and concentration gradients at the surface are evaluated and displayed in tabular form. A decent agreement is found in the present outcomes with previously issued work. Furthermore, it is found that the growth of the thermal-radiation increases the gas temperature. The present study is useful for various industrial applications like metal and polymer extrusion, continuous casting, cooling process, nuclear plant and many more.
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- 2022
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19. Economic assessment of industrial solar water heating system
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Rehman Shafiqur, Sahin Ahmet Z., and Al-Sulaiman Fahad A.
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solar photovoltaics ,building integrated photovoltaic systems ,energy ,renewable energy ,cost of energy ,Engineering (General). Civil engineering (General) ,TA1-2040 ,Mechanics of engineering. Applied mechanics ,TA349-359 - Abstract
In the present work, solar water heating systems having nominal water usage of 24 cubic meters per day are considered. To identify the better option, both technologically and economically, a typical geographical location in Saudi Arabia, namely Abha, is considered. Internal rate of return (IRR) values for the solar collectors with glazing are found to be higher as compared with that of the unglazed type. The glazed type collectors are found to be more efficient, provide greater savings in fuel consumption, and result in the reduction of greenhouse gas (GHG) emissions. The findings of this study can be used for locations with similar types of climatic conditions in any part of the world.
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- 2022
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20. Joint Link Rate Selection and Adaptive Forward Error Correction for High-Rate Wireless Multicast
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Thomas Geithner, Fikret Sivrikaya, and Sahin Albayrak
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802.11 ,forward error correction ,network coding ,rate sampling ,reliable multicast ,transmission rate control ,Telecommunication ,TK5101-6720 ,Transportation and communications ,HE1-9990 - Abstract
Multicast communication over wireless networks has many potential applications, such as real-time audiovisual content distribution or digital signage systems with multiple remote terminals. However, today’s common 802.11 networks cannot fully support such applications at the link layer due to the technical challenges in achieving both high transmission rate and high reliability for multicast data transfers. Those challenges primarily emerge from the inapplicability of immediate acknowledgment mechanisms of unicast transmissions to the multicast case and the need for finding a common transmission rate for all receivers with diverse channel conditions. The research literature in this domain mainly addresses the problem at the higher layers of the protocol stack. In this article, we present a novel approach that combines wireless link rate selection with an adaptive packet-level Forward Error Correction (FEC) mechanism in order to achieve high-rate and highly reliable multicast in 802.11 wireless networks. The integration of FEC into the 802.11 MAC layer allows direct interaction between the transmission rate and the coding scheme. As a result, potential packet losses caused by higher link rates can be compensated by the adjustable redundancy provided by FEC. In combination with an aggregated receiver feedback mechanism, this yields improved transmission efficiency and reliability for wireless multicast. We investigate this approach in a simulation environment under a realistic wireless channel model in various application scenarios with up to 50 receivers. The results represent significant performance improvements, in terms of throughput, channel utilization, and packet loss, over the state-of-the-art methods for reliable wireless multicast.
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- 2022
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21. Aeroelastic analysis of straight-bladed vertical axis wind turbine blade
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Fadlalla Amin A.M., Sahin Ahmet Z., Ouakad Hassen M., and Bahaidarah Haitham
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aeroelastic structural analysis ,straight bladed vawts ,thin beam theory ,reduced order modeling ,dmst model ,Engineering (General). Civil engineering (General) ,TA1-2040 ,Mechanics of engineering. Applied mechanics ,TA349-359 - Abstract
To prevent flutter phenomena in a wind turbine, minimize vibration and increase the blades' life, a systematic analysis is required to investigate the effects between the cyclic aerodynamic loads and the structural performance of the turbine. A dynamic analysis of a straight-bladed vertical axis wind turbine (SB-VAWT) blade is investigated in this paper, and a simplified approach for the energy equations of an Eulerian beam subjected to twist and transverse bending deflections is introduced. The aerodynamic loads are estimated using the double multiple stream tube models. They are introduced into the dynamic model in the aeroelastic coupling, where the structural displacements are fed back to update the aerodynamic loads by utilizing the average acceleration method for the numerical integration of the equations. Reduced order modeling is then imposed based on the first modes of vibration. It is found that the structural displacement has little effect on the aerodynamic loads, and SBVAWTs experience higher transverse displacements compared with those in curved-blade VAWTs.
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- 2022
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22. Chiral exceptional point enhanced active tuning and nonreciprocity in micro-resonators
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Lee, Hwaseob, Chang, Lorry, Kecebas, Ali, Mao, Dun, Xiao, Yahui, Li, Tiantian, Alù, Andrea, Özdemir, Sahin K., and Gu, Tingyi
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Physics - Optics - Abstract
Exceptional points (EPs) have been extensively explored in mechanical, acoustic, plasmonic, and photonic systems. However, little is known about the role of EPs in tailoring the dynamic tunability of optical devices. A specific type of EPs known as chiral EPs has recently attracted much attention for controlling the flow of light and for building sensors with better responsivity. A recently demonstrated route to chiral EPs via lithographically defined symmetric Mie scatterers on the rim of resonators has not only provided the much-needed mechanical stability for studying chiral EPs but also helped reduce losses originating from nanofabrication imperfections, facilitating the in-situ study of chiral EPs and their contribution to the dynamics and tunability of resonators. Here, we use asymmetric Mie scatterers to break the rotational symmetry of a microresonator, to demonstrate deterministic thermal tuning across a chiral EP, and to demonstrate EP-mediated chiral optical nonlinear response and efficient electro-optic tuning. Our results indicate asymmetric electro-optic modulation with up to 17dB contrast at GHz and CMOS-compatible voltage levels. Such wafer-scale nano-manufacturing of chiral electro-optic modulators and the chiral EP-tailored tunning may facilitate new micro-resonator functionalities in quantum information processing, electromagnetic wave control, and optical interconnects.
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- 2024
23. A Systematic Survey on Instructional Text: From Representation Formats to Downstream NLP Tasks
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Safa, Abdulfattah, Kapanadze, Tamta, Uzunoğlu, Arda, and Şahin, Gözde Gül
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Computer Science - Computation and Language - Abstract
Recent advances in large language models have demonstrated promising capabilities in following simple instructions through instruction tuning. However, real-world tasks often involve complex, multi-step instructions that remain challenging for current NLP systems. Despite growing interest in this area, there lacks a comprehensive survey that systematically analyzes the landscape of complex instruction understanding and processing. Through a systematic review of the literature, we analyze available resources, representation schemes, and downstream tasks related to instructional text. Our study examines 177 papers, identifying trends, challenges, and opportunities in this emerging field. We provide AI/NLP researchers with essential background knowledge and a unified view of various approaches to complex instruction understanding, bridging gaps between different research directions and highlighting future research opportunities.
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- 2024
24. Shape evolution in even-mass $^{98-104}$Zr isotopes via lifetime measurements using the $\gamma\gamma$-coincidence technique
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Pasqualato, G., Ansari, S., Heines, J. S., Modamio, V., Görgen, A., Korten, W., Ljungvall, J., Clément, E., Dudouet, J., Lemasson, A., Rodríguez, T. R., Allmond, J. M., Arici, T., Beckmann, K. S., Bruce, A. M., Doherty, D., Esmaylzadeh, A., Gamba, E. R., Gerhard, L., Gerl, J., Georgiev, G., Ivanova, D. P., Jolie, J., Kim, Y. -H., Knafla, L., Korichi, A., Koseoglou, P., Labiche, M., Lalkovski, S., Lauritsen, T., Li, H. -J., Pedersen, L. G., Pietri, S., Ralet, D., Regis, J. M., Rudigier, M., Saha, S., Sahin, E., Siem, S., Singh, P., öderström, P. -A., Theisen, C., Tornyi, T., Vandebrouck, M., Witt, W., Zielińska, M., Barrientos, D., Bednarczyk, P., Benzoni, G., Boston, A. J., Boston, H. C., Bracco, A., Cederwall, B, Ciemala, M., de France, G., Domingo-Pardo, C., Eberth, J., Gadea, A., González, V., Gottardo, A., Harkness-Brennan, L. J., Hess, H., Judson, D. S., Jungclaus, A., Lenzi, S. M., Leoni, S., Menegazzo, R., Mengoni, D., Michelagnoli, C., Napoli, D. R., Nyberg, J., Podolyak, Zs., Pullia, A., Recchia, F., Reiter, P., Rezynkina, K., Salsac, M. D., Sanchis, E., Şenyiğit, M., Siciliano, M., Simpson, J., Sohler, D., Stezowski, O., Valiente-Dobón, J. J., and Verney, D.
- Subjects
Nuclear Experiment - Abstract
The Zirconium (Z = 40) isotopic chain has attracted interest for more than four decades. The abrupt lowering of the energy of the first $2^+$ state and the increase in the transition strength B(E2; $2_1^\rightarrow 0_1^+$ going from $^{98}$Zr to $^{100}$Zr has been the first example of "quantum phase transition" in nuclear shapes, which has few equivalents in the nuclear chart. Although a multitude of experiments have been performed to measure nuclear properties related to nuclear shapes and collectivity in the region, none of the measured lifetimes were obtained using the Recoil Distance Doppler Shift method in the $\gamma\gamma$-coincidence mode where a gate on the direct feeding transition of the state of interest allows a strict control of systematical errors. This work reports the results of lifetime measurements for the first yrast excited states in $^{98-104}$Zr carried out to extract reduced transition probabilities. The new lifetime values in $\gamma\gamma$-coincidence and $\gamma$-single mode are compared with the results of former experiments. Recent predictions of the Interacting Boson Model with Configuration Mixing, the Symmetry Conserving Configuration Mixing model based on the Hartree-Fock-Bogoliubov approach and the Monte Carlo Shell Model are presented and compared with the experimental data.
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- 2024
- Full Text
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25. GECTurk WEB: An Explainable Online Platform for Turkish Grammatical Error Detection and Correction
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Gebeşçe, Ali and Şahin, Gözde Gül
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Computer Science - Computation and Language ,Computer Science - Artificial Intelligence - Abstract
Sophisticated grammatical error detection/correction tools are available for a small set of languages such as English and Chinese. However, it is not straightforward -- if not impossible -- to adapt them to morphologically rich languages with complex writing rules like Turkish which has more than 80 million speakers. Even though several tools exist for Turkish, they primarily focus on spelling errors rather than grammatical errors and lack features such as web interfaces, error explanations and feedback mechanisms. To fill this gap, we introduce GECTurk WEB, a light, open-source, and flexible web-based system that can detect and correct the most common forms of Turkish writing errors, such as the misuse of diacritics, compound and foreign words, pronouns, light verbs along with spelling mistakes. Our system provides native speakers and second language learners an easily accessible tool to detect/correct such mistakes and also to learn from their mistakes by showing the explanation for the violated rule(s). The proposed system achieves 88,3 system usability score, and is shown to help learn/remember a grammatical rule (confirmed by 80% of the participants). The GECTurk WEB is available both as an offline tool at https://github.com/GGLAB-KU/gecturkweb or online at www.gecturk.net.
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- 2024
26. Codes on Weighted Projective Planes
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Çakıroğlu, Yağmur, Nardi, Jade, and Şahin, Mesut
- Subjects
Mathematics - Algebraic Geometry ,Computer Science - Information Theory - Abstract
We comprehensively study weighted projective Reed-Muller (WPRM) codes on weighted projective planes $\mathbb{P}(1,a,b)$. We provide the universal Gr\"obner basis for the vanishing ideal of the set $Y$ of $\mathbb{F}_q$--rational points of $\mathbb{P}(1,a,b)$ to get the dimension of the code. We determine the regularity set of $Y$ using a novel combinatorial approach. We employ footprint techniques to compute the minimum distance.
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- 2024
27. Near-Infrared Spectroscopy of the Sun and Solar Analog Star HD 76151: Compiling an Extensive Line List in Y-, J-, H-, and K-Bands
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Senturk, S., Sahin, T., Guney, F., Bilir, S., and Marismak, M.
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Astrophysics - Solar and Stellar Astrophysics - Abstract
Determining the physical nature of a star requires precise knowledge of its stellar atmospheric parameters, including effective temperature, surface gravity, and metallicity. This study presents a new atomic line list covering a broad spectral range (1-2.5 $\mu$m; $YJHK$-bands) for iron (Fe) and $\alpha$-elements (Ca, Mg, Ti, Si) to improve stellar parameter determination using near-infrared (NIR) spectroscopy. We highlight the limitations of existing line lists, stemming primarily from inconsistencies in oscillator strengths for ionized iron lines within the APOGEE DR17. The line list was validated using the high-resolution and high-quality disc-center NIR spectra of the Sun and its solar analog HD 76151. As a result of the spectroscopic analyses, the effective temperature of HD 76151 was calculated as 5790$\pm$170 K, surface gravity as 4.35$\pm$0.18 cgs, metal abundance as 0.24$\pm$0.09 dex, and microturbulence velocity of 0.30$^{\rm +0.5}_{\rm -0.3}$ km s$^{-1}$ by combining the optical and NIR line lists. A comparison of the model atmospheric parameters calculated for HD 76151 with the PARSEC isochrones resulted in a stellar mass of $1.053_{-0.068}^{+0.056} M_{\odot}$, radius $1.125_{-0.011}^{+0.035} R_{\odot}$, and an age of 5.5$^{\rm +2.5}_{\rm -2.1}$ Gyr. For the first time, kinematic and dynamical orbital analyses of HD 76151 using a combination of Gaia astrometric and spectroscopic data showed that the star was born in a metal-rich region within the Solar circle and is a member of the thin disc population. Thus, the slightly metal-rich nature of the star, as reflected in its spectroscopic analysis, was confirmed by dynamical orbital analysis., Comment: 31 pages, including 8 figures and 13 tables, accepted for publication in the Astrophysical Journal
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- 2024
28. Linguistically-Informed Multilingual Instruction Tuning: Is There an Optimal Set of Languages to Tune?
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Soykan, Gürkan and Şahin, Gözde Gül
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Computer Science - Computation and Language ,Computer Science - Machine Learning ,I.2.7 - Abstract
Multilingual language models often perform unevenly across different languages due to limited generalization capabilities for some languages. This issue is significant because of the growing interest in making universal language models that work well for all languages. Instruction tuning with multilingual instruction-response pairs has been used to improve model performance across various languages. However, this approach is challenged by high computational costs, a lack of quality tuning data for all languages, and the "curse of multilinguality" -- the performance drop per language after adding many languages. Recent studies have found that working with datasets with few languages and a smaller number of instances can be beneficial. Yet, there exists no systematic investigation into how choosing different languages affects multilingual instruction tuning. Our study proposes a method to select languages for instruction tuning in a linguistically informed way, aiming to boost model performance across languages and tasks. We use a simple algorithm to choose diverse languages and test their effectiveness on various benchmarks and open-ended questions. Our results show that this careful selection generally leads to better outcomes than choosing languages at random. We suggest a new and simple way of enhancing multilingual models by selecting diverse languages based on linguistic features that could help develop better multilingual systems and guide dataset creation efforts. All resources, including the code for language selection and multilingual instruction tuning, are made available in our official repository at https://github.com/GGLAB-KU/ling-informed-mit enabling reproducibility and further research in this area., Comment: 31 pages, 6 figures
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- 2024
29. Self-consistent electrostatic formalism of bulk electrolytes based on the asymmetric treatment of the short- and long-range ion interactions
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Buyukdagli, Sahin
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Condensed Matter - Soft Condensed Matter - Abstract
We predict the thermodynamic behavior of bulk electrolytes from an ionic Hard-Core (HC) size-augmented self-consistent formalism incorporating asymmetrically the short- and long-range ion interactions via their virial and cumulant treatment, respectively. The characteristic splitting length separating these two ranges is obtained from a variational equation solved together with the Schwinger-Dyson (SD) equations. Via comparison with simulation results from the literature, we show that the asymmetric treatment of the distinct interaction ranges extends significantly the validity regime of our previously developed purely cumulant-level Debye-Huckel (DH) theory. Namely, for monovalent solutions with typical ion sizes, the present formalism can accurately predict mutually the HC-dominated liquid pressure and the electrostatic correlation-driven internal energies up to molar concentrations. We evaluate as well the screening length of the liquid and investigate the deviations of the intermolecular interaction range from the DH length. We show that in fair agreement with simulations and experiments, our theory can also reproduce the overscreening and underscreening effects occurring respectively in mono- and multivalent electrolytes.
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- 2024
30. WAVE-UNET: Wavelength based Image Reconstruction method using attention UNET for OCT images
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Viqar, Maryam, Sahin, Erdem, Madjarova, Violeta, Stoykova, Elena, and Hong, Keehoon
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Electrical Engineering and Systems Science - Image and Video Processing ,Computer Science - Computer Vision and Pattern Recognition ,Computer Science - Machine Learning ,Physics - Computational Physics ,Physics - Optics - Abstract
In this work, we propose to leverage a deep-learning (DL) based reconstruction framework for high quality Swept-Source Optical Coherence Tomography (SS-OCT) images, by incorporating wavelength ({\lambda}) space interferometric fringes. Generally, the SS-OCT captured fringe is linear in wavelength space and if Inverse Discrete Fourier Transform (IDFT) is applied to extract depth-resolved spectral information, the resultant images are blurred due to the broadened Point Spread Function (PSF). Thus, the recorded wavelength space fringe is to be scaled to uniform grid in wavenumber (k) space using k-linearization and calibration involving interpolations which may result in loss of information along with increased system complexity. Another challenge in OCT is the speckle noise, inherent in the low coherence interferometry-based systems. Hence, we propose a systematic design methodology WAVE-UNET to reconstruct the high-quality OCT images directly from the {\lambda}-space to reduce the complexity. The novel design paradigm surpasses the linearization procedures and uses DL to enhance the realism and quality of raw {\lambda}-space scans. This framework uses modified UNET having attention gating and residual connections, with IDFT processed {\lambda}-space fringes as the input. The method consistently outperforms the traditional OCT system by generating good-quality B-scans with highly reduced time-complexity.
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- 2024
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31. Resonance Reduction Against Adversarial Attacks in Dynamic Networks via Eigenspectrum Optimization
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Sahin, Alp, Kozachuk, Nicolas, Blum, Rick S., and Bhattacharya, Subhrajit
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Computer Science - Social and Information Networks ,Mathematics - Optimization and Control - Abstract
Resonance is a well-known phenomenon that happens in systems with second order dynamics. In this paper we address the fundamental question of making a network robust to signal being periodically pumped into it at or near a resonant frequency by an adversarial agent with the aim of saturating the network with the signal. Towards this goal, we develop the notion of network vulnerability, which is measured by the expected resonance amplitude on the network under a stochastically modeled adversarial attack. Assuming a second order dynamics model based on the network graph Laplacian matrix and a known stochastic model for the adversarial attack, we propose two methods for minimizing the network vulnerability that leverage the principle of eigenspectrum optimization. We provide extensive numerical results analyzing the effects of both methods., Comment: 13 pages, 18 figures
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- 2024
32. A Zero-Shot Open-Vocabulary Pipeline for Dialogue Understanding
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Safa, Abdulfattah and Şahin, Gözde Gül
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Computer Science - Computation and Language ,Computer Science - Artificial Intelligence - Abstract
Dialogue State Tracking (DST) is crucial for understanding user needs and executing appropriate system actions in task-oriented dialogues. Majority of existing DST methods are designed to work within predefined ontologies and assume the availability of gold domain labels, struggling with adapting to new slots values. While Large Language Models (LLMs)-based systems show promising zero-shot DST performance, they either require extensive computational resources or they underperform existing fully-trained systems, limiting their practicality. To address these limitations, we propose a zero-shot, open-vocabulary system that integrates domain classification and DST in a single pipeline. Our approach includes reformulating DST as a question-answering task for less capable models and employing self-refining prompts for more adaptable ones. Our system does not rely on fixed slot values defined in the ontology allowing the system to adapt dynamically. We compare our approach with existing SOTA, and show that it provides up to 20% better Joint Goal Accuracy (JGA) over previous methods on datasets like Multi-WOZ 2.1, with up to 90% fewer requests to the LLM API.
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- 2024
33. A mmWave Software-Defined Array Platform for Wireless Experimentation at 24-29.5 GHz
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Ganesh, Ashwini Pondeycherry, Perre, Anthony, Sahin, Alphan, Guvenc, Ismail, and Floyd, Brian A.
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Electrical Engineering and Systems Science - Systems and Control - Abstract
Advanced millimeter-wave software-defined array (SDA) platforms, or testbeds at affordable costs and high performance are essential for the wireless community. In this paper, we present a low-cost, portable, and programmable SDA that allows for accessible research and experimentation in real time. The proposed platform is based on a 16-element phased-array transceiver operating across 24-29.5 GHz, integrated with a radio-frequency system-on-chip board that provides data conversion and baseband signal-processing capabilities. All radio-communication parameters and phased-array beam configurations are controlled through a high-level application program interface. We present measurements evaluating the beamforming and communication link performance. Our experimental results validate that the SDA has a beam scan range of -45 to +45 degrees (azimuth), a 3 dB beamwidth of 20 degrees, and support up to a throughput of 1.613 Gb/s using 64-QAM. The signal-to-noise ratio is as high as 30 dB at short-range distances when the transmit and receive beams are aligned.
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- 2024
34. An Efficient Low-Complexity RSMA Scheme for Multi-User Decode-and-Forward Relay Systems
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Sümer, Ahmet Sacid, Şahin, Mehmet Mert, and Arslan, Hüseyin
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Electrical Engineering and Systems Science - Signal Processing - Abstract
Rate-Splitting Multiple Access (RSMA) is a promising strategy for ensuring robust transmission in multi-antenna wireless systems. In this paper, we investigate the performance of RSMA in a downlink Decode-and-Forward (DF) relay scenario under two phases with imperfect Channel State Information (CSI) at the transmitter and the relay. In particular, in the first phase, the Base Station (BS) initially transmits to both BS Users (BUs) and the relay. In the second phase, the relay decodes and forwards the received signals to Relay Users (RUs) outside the BS coverage area. Furthermore, we investigate a scenario where the relay broadcasts a common stream intended for the RUs in the second phase. Due to the broadcast nature of the transmission, this stream is inadvertently received by both the RUs and the BUs. Concurrently, the BS utilizes Spatial Division Multiple Access (SDMA) to transmit private streams to the BUs, resulting in BUs experiencing residual interference from the common stream transmitted from relay. Incorporating this residual common stream interference into our model results in a significant enhancement of the overall sum-rate achieved at the BUs. We derive a tractable lower bound on the ergodic sum-rates, enables us to develop closed-form solutions for power allocation that maximize the overall sum-rate in both phases. Extensive simulations validate that our proposed power allocation algorithm, in conjunction with a low-complexity precoder, significantly improves the sum-rate performance of DF relay RSMA networks compared to the SDMA-based benchmark designs under imperfect CSI at the transmitter and relay.
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- 2024
35. A Bayesian Optimization through Sequential Monte Carlo and Statistical Physics-Inspired Techniques
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Lebedev, Anton, Warford, Thomas, and Şahin, M. Emre
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Statistics - Computation ,Computer Science - Distributed, Parallel, and Cluster Computing ,Physics - Data Analysis, Statistics and Probability ,G.3 ,G.4 ,D.2.12 - Abstract
In this paper, we propose an approach for an application of Bayesian optimization using Sequential Monte Carlo (SMC) and concepts from the statistical physics of classical systems. Our method leverages the power of modern machine learning libraries such as NumPyro and JAX, allowing us to perform Bayesian optimization on multiple platforms, including CPUs, GPUs, TPUs, and in parallel. Our approach enables a low entry level for exploration of the methods while maintaining high performance. We present a promising direction for developing more efficient and effective techniques for a wide range of optimization problems in diverse fields., Comment: 8 pages, 7 figures, accepted to the International Conference on Computer Science 2023
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- 2024
- Full Text
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36. Optimization of multiple battery swapping stations with mobile support for ancillary services
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Mustafa Cagatay Kocer, Ahmet Onen, Taha Selim Ustun, and Sahin Albayrak
- Subjects
battery swapping station ,mobile swapping station ,vehicle-to-grid ,ancillary services ,optimal scheduling ,electric vehicle ,General Works - Abstract
The recent developments in electric vehicles (EVs) causes several issues that have not been satisfactorily addressed. One of the foremost problems is the charging–discharging processes of EV batteries with diverse characteristics. Although a charging station is the first choice in this regard, a battery swap station (BSS) is also a suitable alternative solution as it eliminates long waiting periods and battery degradation due to fast charging. BSS has the capability to ensure prompt and efficient service for electric vehicles. Since BSS has a large number of battery systems, optimum planning of the charging–discharging operations of the batteries is critical for both BSS and the grid. This study presents an optimal charging–discharging schedule for multiple BSSs based on the swap demand of privately owned EVs and electric bus (EB) public transportation system. In addition, BSSs reinforce the power grid by providing ancillary services such as peak shaving and valley filling with demand response programs. In order to increase the flexibility of the operation, the mobile swapping station (MSS) concept, an innovative and dynamic service, is introduced to the literature and added to the model. The results indicate that BSS is an essential agent in the ancillary services market and the MSS concept is a yielding solution for both BSSs and power networks. Last, the data utilized in the study for swap demand calculation and power grid analysis are real-world data from Berlin, Germany.
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- 2022
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37. Behaviors Related to Primary School Principals' Crisis Management Skills: In the Context of the February 6th 2023 Earthquake
- Author
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Gökçe Özdemir, Sevilay Sahin, and Selin Türkoglu Özdemir
- Abstract
In the face of the unpredictable nature of crises, it is expected that school principals exhibit behaviors aimed at maintaining the psychological well-being of teachers, students, and parents along with the educational processes. The sudden occurrence of the February 6, 2023 earthquakes, has presented an important crisis situation in which school principals are expected to display the desired behaviors. This research aims to reveal to what extent school principals demonstrated their crisis management skills in the context of the February 6, 2023 earthquake and what behaviors they exhibited during crisis management processes, based on teachers' opinions. The research was carried out with a mixed method approach in which quantitative and qualitative research methods were used together. The sample of the research consisted of 295 teachers, and the study group consisted of 18 teachers selected from the same sample by purposeful sampling method. Quantitative data of the research were collected using the crisis management scale, and qualitative data were collected using a semi-structured interview form. According to the quantitative results of the research, it was determined that the crisis management skill levels of school principals were "mostly" in the pre-crisis and post-crisis periods, and "sometimes" during the crisis period. When teachers' opinions were examined, it was seen that school principals were unprepared for crises arising from natural disasters such as earthquakes and that they mostly followed the Ministry of National Education guidelines and therefore lacked initiative. School principals who were able to take initiative took action to support the psychological health of teachers, students and parents by meeting their needs and gained their trust.
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- 2024
38. A Proposal for Policy Framework and Emergency Action Plan after COVID-19 for Distance Education Practices in Higher Education
- Author
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Mehmet Yavuz, Münevver Gündüz, Sinem Çilligöl Karabey, Yusuf Zafer Can Ugurhan, Selçuk Karaman, Engin Kursun, Halil I?Brahim Bülbül, Hasan Karal, Levent Sahin, Muhammet Recep Okur, Sinan Aydin, and Vehbi Aytekin Sanalan
- Abstract
This study aimed to investigate distance education practices in higher education during the pandemic, focusing on lived experiences, and proposing a policy decision framework for future distance education in similar conditions. Additionally, the study aimed to establish a design framework for an Emergency Action Plan for similar crisis periods. In the study, a case study was used to provide a detailed examination of the current situation's characteristics. The study group consisted of 63 administrators from 34 universities who actively participated in decision-making during the pandemic. Data were collected through 11 online focus group interviews, and the Miles-Huberman Model was used for analysis. The study proposed a policy decision framework for distance education in the post-pandemic period, consisting of 11 headings such as blended learning, open course materials, and Distance Education Center structuring. Additionally, the study presented an emergency action plan framework consisting of six components, including keeping the technological infrastructure working and supporting face-to-face courses with distance education. This study provides valuable insights for universities in preparing for potential crises and improving their distance education practices.
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- 2024
39. Examination of the Mediating Role of Attachment Dimensions in the Link between Suicide Probability and Cognitive Distortions about Relationships in University Students
- Author
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Gulin Yazici-Celebi, Muge Yilmaz, Muhammed Enes Karacoskun, and Aybuke Irem Sahin
- Abstract
Suicide, which is defined as an individual's intentionally attempting to end his or her life, is considered an important public health problem. In this study, it was aimed to examine the relationship between cognitive distortions and suicide probability in university students who are in age groups at risk for suicide, and to examine the mediating roles of the attachment dimensions of anxiety and avoidance, in this relationship. The study group consisted of 441 university students. In the study, Suicide Probability Scale, Experiences in Close Relationships Inventory, Cognitive Distortions in Relationships Scale and a personal information form were used as data collection tools. In accordance with the purpose of the study, a correlation analysis between variables and regression analyses were applied to examine the mediating roles of avoidance and anxiety in the relationship between cognitive distortions and suicide probability. The findings showed that there was a moderate positive correlational relationship between suicide probability scores and avoidance scores and there was a moderate positive correlational relationship between suicide probability scores and cognitive distortion scores. It was shown that there were low and moderate positive correlations between cognitive distortion scores, and avoidance and anxiety scores. The results of the mediation analyses showed that anxiety and avoidance had a partial mediating role in the relationship between cognitive distortion and suicide probability. The results were discussed in light of the literature.
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- 2024
40. Benefits, Challenges, and Methods of Artificial Intelligence (AI) Chatbots in Education: A Systematic Literature Review
- Author
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Sahin Gökçearslan, Cansel Tosun, and Zeynep Gizem Erdemir
- Abstract
In many fields, AI chatbots continue to be popular with new tools and attract the attention of universities, K12 schools, educational organizations, and researchers. The aim of this research is to review the research on AI chatbots by restricting it to the category of education and to examine this research from a methodological point of view. Therefore, we performed a systematic literature review with a sample of 37 SSCI articles published in the educational context. Within the scope of the selected studies, the advantages and disadvantages of AI chatbots in education for students and educators, as well as the types of chatbots used, year, keywords, and method were analyzed. According to the research results, increased motivation to learn and language skill development are advantages for students, while cost-effectiveness and reduced workload are advantages for educators. Limited interaction, misleading answers for learners, originality, and plagiarism are the most common disadvantages for educators. The study also includes research results and recommendations related to the methodological review.
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- 2024
41. Exploring the Role of Individual Differences on Instructors' Technology Acceptance in Online Education through a Motivational Perspective
- Author
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Ulas Ilic, Ferhan Sahin, and Ezgi Dogan
- Abstract
The present study aims to investigate the potential variables that influence the faculty members' intention to continue using online learning systems during and after the pandemic based on extended Technology Acceptance Model (TAM) and Self Determination Theory (SDT), and to study individual differences between these variables. The methodology of the study was based on survey research and causal comparative methods. Convenience sampling method was used to identify the participants of the study, who are 302 faculty members working at twelve different state universities. Explanatory and confirmatory factor analysis (EFA-CFA) were used to test the factor structure of the data collection tool and to validate the tool through examining the model fit. Descriptive statistics were used to examine the distribution of the dependent variable scores of the participants, and one-way MANOVA was used to compare the variables based on individual differences. The findings indicated that CMP had the highest mean score, followed by the constructs of SDT (competence, autonomy, relatedness). A significant difference for male participants was observed in perceived ease of use and competence variables based on gender. No significant difference was found between the variables based on academic title. The present study established that all variables except relatedness indicated a significant difference that favors instructors with high and medium level online learning experience. It was concluded that the comparison of the motivational variables based on the individual differences of the instructors, which have critical importance in online education as well as in higher education, can contribute to the establishment of effective and sustainable quality learning environments (distance or hybrid) and to the existing literature.
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- 2024
42. The Reflections of the 'Stop Climate Change Digital Game' on Primary School Students' Learning about Climate Change
- Author
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Sahin Idil and Orkun Kocak
- Abstract
Climate change and its effects are impacting our world more and more with each passing day. For this reason, we must ensure that our children, as the society of the future, grow up as individuals with high environmental awareness, being aware of climate change and its effects. The aim of this study is to inform students about the subject of climate change and to educate them as individuals with climate change literacy. In this context, a digital game about climate change and its effects was developed for primary school students. A qualitative research method and techniques were adapted in this research. Interview, observation, and document analysis techniques were used to ensure variety in data acquisition in the research. The study was conducted in the 2022 spring semester during the science courses. It was conducted at an urban primary school in Ankara. 22 fourth grade students were participated as control group and 23 fourth grade students were participated as treatment group in the study. It was determined that the students enjoyed this game, called Stop Climate Change; they had fun and simultaneously learned about concepts related to climate change.
- Published
- 2024
43. Multimodality in Distance Education during COVID-19: Teachers' Perspectives and Practices
- Author
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Halil I?Brahim Sahin and Mehmtay
- Abstract
With the outbreak of the COVID-19 pandemic, governments around the world were forced to take emergency measures in every aspect of life including education. Instead of the prevalent face-to-face mode of teaching, institutions turned to online teaching one by one. This brought many issues along with it. Because of distance education, it became quite challenging for teachers to maintain the multimodal nature of communication. This research aims to examine in-service teachers' perceptions and actual practices regarding multimodal instruction in online lessons during the COVID-19 pandemic from a descriptive point of view. The research followed an explanatory sequential mixed-methods design. Firstly, to examine the beliefs and preferences of teachers, a 24-item questionnaire (henceforth Multimodal Teaching Questionnaire) that was adapted from a previously developed questionnaire by Bulut et al. (2015) was used. Secondly, 72 hours of distance lessons from 36 teachers were observed via Zoom online conferencing tool. The results showed a discrepancy between the teachers' statements and their actual practices regarding multimodality. While most of them reported extensive use of multimodality in their instruction, observations showed that in the majority of their lessons, only one or two modes were used.
- Published
- 2024
44. Generalized Additive Modeling of Building Inertia Thermal Energy Storage for Integration Into Smart Grid Control
- Author
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Marcus Voss, Jan F. Heinekamp, Sabine Krutzsch, Friedrich Sick, Sahin Albayrak, and Kai Strunz
- Subjects
Building inertia thermal energy storage ,energy management ,generalized additive model ,mixed-integer linear programming ,sector coupling ,smart grid ,Electrical engineering. Electronics. Nuclear engineering ,TK1-9971 - Abstract
The structural mass of a building provides inherent thermal storage capability. Through sector coupling, the building mass can provide additional flexibility to the electric power system, using, for instance, combined heat and power plants or power-to-heat. In this work, a mathematical model of building inertia thermal energy storage (BITES) for integration into optimized smart grid control is introduced. It is shown how necessary model parameters can be obtained using generalized additive modeling (GAM) based on measurable building data. For this purpose, it is demonstrated that the ceiling surface temperature can serve as a proxy for the current state of energy. This allows for real-world implementation using only temperature sensors as additionally required hardware. Compared with linear modeling, GAM enable improved modeling of the nonlinear characteristics and interactions of external factors influencing the storage operation. Two case studies demonstrate the potential of using building storage as part of a virtual power plant (VPP) for optimized smart grid control. In the first case study, BITES is compared with conventionally used hot water tanks, revealing economic benefits for both the VPP and building operator. The second case study investigates the potential for savings in CO2 emission and grid connection capacity. It shows similar benefits when using BITES compared to using battery storage, without the need for hardware investment. Given the ubiquity of buildings and the recent advances in building control systems, BITES offers great potential as an additional source of flexibility to the low-carbon energy systems of the future.
- Published
- 2021
- Full Text
- View/download PDF
45. On the Optimal Radius and Subcarrier Mapping for Binary Modulation on Conjugate-Reciprocal Zeros
- Author
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Huggins, Parker and Sahin, Alphan
- Subjects
Electrical Engineering and Systems Science - Signal Processing - Abstract
In this work, we investigate the radius maximizing reliability for binary modulation on conjugate-reciprocal zeros (BMOCZ) implemented with both maximum likelihood (ML) and direct zero-testing (DiZeT) decoders. We first show that the optimal radius for BMOCZ is a function of the employed decoder and that the radius maximizing the minimum distance between polynomial zeros does not maximize the minimum distance of the final code. While maximizing zero separation offers an almost optimal solution with the DiZeT decoder, simulations show that the ML decoder outperforms the DiZeT decoder in both additive white Gaussian noise (AWGN) and fading channels when the radius is chosen to maximize codeword separation. Finally, we analyze different sequence-to-subcarrier mappings for BMOCZ-based orthogonal frequency division multiplexing (OFDM). We highlight a flexible time-frequency OFDM waveform that avoids distortion introduced by a frequency-selective channel at the expense of a higher peak-to-average power ratio (PAPR)., Comment: This work has been accepted for presentation at IEEE MILCOM 2024
- Published
- 2024
46. Interference-Free Backscatter Communications for OFDM-Based Symbiotic Radio
- Author
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Janjua, Muhammad Bilal, Şahin, Alphan, and Arslan, Hüseyin
- Subjects
Electrical Engineering and Systems Science - Signal Processing - Abstract
This study proposes an orthogonal frequency division multiplexing (OFDM) based scheme to achieve interference-free backscatter communications (BC) in a symbiotic radio system. In specific, we propose three frequency shift keying (FSK) based backscatter modulation schemes to shift the primary signal, i.e., the OFDM symbols transmitted from a base station (BS), in the frequency domain to transmit its information. Symbiotically, the BS empties specific subcarriers within the band so that the received frequency-shifted signals from the backscatter device and the primary signal are always orthogonal. The first scheme relies on the combination of on-off keying (OOK) within the FSK modulation while the second and the third schemes are based on the conventional FSK modulation with different in-band null-subcarrier allocation. These schemes allow the use of non-coherent detection at the receiver which addresses the channel estimation challenge for the signals arriving from a backscatter device. We derive the bit-error rate performance of the detector theoretically. The comprehensive simulations show that the proposed approach achieves a lower bit-error rate up to 10-4 at 30 dB with BC by eliminating direct link interference.
- Published
- 2024
47. SceneMotion: From Agent-Centric Embeddings to Scene-Wide Forecasts
- Author
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Wagner, Royden, Tas, Ömer Sahin, Steiner, Marlon, Konstantinidis, Fabian, Königshof, Hendrik, Klemp, Marvin, Fernandez, Carlos, and Stiller, Christoph
- Subjects
Computer Science - Computer Vision and Pattern Recognition ,Computer Science - Robotics - Abstract
Self-driving vehicles rely on multimodal motion forecasts to effectively interact with their environment and plan safe maneuvers. We introduce SceneMotion, an attention-based model for forecasting scene-wide motion modes of multiple traffic agents. Our model transforms local agent-centric embeddings into scene-wide forecasts using a novel latent context module. This module learns a scene-wide latent space from multiple agent-centric embeddings, enabling joint forecasting and interaction modeling. The competitive performance in the Waymo Open Interaction Prediction Challenge demonstrates the effectiveness of our approach. Moreover, we cluster future waypoints in time and space to quantify the interaction between agents. We merge all modes and analyze each mode independently to determine which clusters are resolved through interaction or result in conflict. Our implementation is available at: https://github.com/kit-mrt/future-motion, Comment: 7 pages, 3 figures, ITSC 2024; v2: added details about waypoint clustering
- Published
- 2024
48. Fleet-mix Electric Vehicle Routing Problem for the E-commerce Delivery with Limited Off-Hour Delivery Implementation
- Author
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Uhm, Hyun-Seop, Ismael, Abdelrahman, Zuniga-Garcia, Natalia, Sahin, Olcay, Cook, James, Auld, Joshua, and Stinson, Monique
- Subjects
Mathematics - Optimization and Control - Abstract
Freight truck electrification for last-mile delivery is one of the most important research topics to reduce the dependency on fossil fuel operations. Although a battery electric truck still has limitations on daily operations with lower driving ranges and higher purchasing cost than a conventional truck, operations with electrified trucks reduce total energy usage and driving noise on routes. In this paper, we propose a fleet-mix and multi-shift electric vehicle routing problem for joint implementation of fleet electrification and off-hour delivery in urban e-commerce delivery systems. Every electrified truck is assumed to have two shifts for both daytime and nighttime delivery operations while conventional trucks can operate during daytime only because of municipal restrictions on nighttime deliveries, which are related to engine noise. Also, every electrified truck must recharge between shifts at its depot. A fleet owner decides the best electrification ratio of the fleet and the proper number of chargers which gives the minimum total cost. The optimization problem is described as a mixed-integer linear programming model including common constraints for vehicle routing problem, recharging constraints, and two-shift operation of electrified trucks. A bi-level VNS-TS heuristic is also suggested for efficient solution search. The upper-level problem assigns trucks with engine type and brief route information using variable neighborhood search heuristic, and the lower-level problem finds the best route of each assigned truck using a tabu search heuristic. Scenarios with different EV driving ranges and nighttime operation availabilities are developed and evaluated with the POLARIS transportation simulation framework, and results are reported.
- Published
- 2024
49. Force Profiling of a Shoulder Bidirectional Fabric-based Pneumatic Actuator for a Pediatric Exosuit
- Author
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Ayazi, Mehrnoosh, Sahin, Ipsita, Mucchiani, Caio, Kokkoni, Elena, and Karydis, Konstantinos
- Subjects
Computer Science - Robotics - Abstract
This paper presents a comprehensive analysis of the contact force profile of a single-cell bidirectional soft pneumatic actuator, specifically designed to aid in the abduction and adduction of the shoulder for pediatric exosuits. The actuator was embedded in an infant-scale test rig featuring two degrees of freedom: an actuated revolute joint supporting shoulder abduction/adduction and a passive (but lockable) revolute joint supporting elbow flexion/extension. Integrated load cells and an encoder within the rig were used to measure the force applied by the actuator and the shoulder joint angle, respectively. The actuator's performance was evaluated under various anchoring points and elbow joint angles. Experimental results demonstrate that optimal performance, characterized by maximum range of motion and minimal force applied on the torso and upper arm, can be achieved when the actuator is anchored at two-thirds the length of the upper arm, with the elbow joint positioned at a 90-degree angle. The force versus pressure and joint angle graphs reveal nonlinear and hysteresis behaviors. The findings of this study yield insights about optimal anchoring points and elbow angles to minimize exerted forces without reducing the range of motion.
- Published
- 2024
50. LaFAM: Unsupervised Feature Attribution with Label-free Activation Maps
- Author
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Karjauv, Aray and Albayrak, Sahin
- Subjects
Computer Science - Computer Vision and Pattern Recognition - Abstract
Convolutional Neural Networks (CNNs) are known for their ability to learn hierarchical structures, naturally developing detectors for objects, and semantic concepts within their deeper layers. Activation maps (AMs) reveal these saliency regions, which are crucial for many Explainable AI (XAI) methods. However, the direct exploitation of raw AMs in CNNs for feature attribution remains underexplored in literature. This work revises Class Activation Map (CAM) methods by introducing the Label-free Activation Map (LaFAM), a streamlined approach utilizing raw AMs for feature attribution without reliance on labels. LaFAM presents an efficient alternative to conventional CAM methods, demonstrating particular effectiveness in saliency map generation for self-supervised learning while maintaining applicability in supervised learning scenarios.
- Published
- 2024
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