Research Outputs
Permanent URI for this communityhttps://hdl.handle.net/20.500.14288/2
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Publication Metadata only A virtual reality toolkit for path planning and manipulation at nano-scale(IEEE Computer Soc, 2006) N/A; N/A; Department of Mechanical Engineering; Varol, Aydın; Günev, İhsan; Başdoğan, Çağatay; Master Student; Master Student; Faculty Member; Department of Mechanical Engineering; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; College of Engineering; N/A; N/A; 125489A virtual reality (VR) toolkit that integrates the human operator into a virtual environment by means of visual and haptic feedback has been developed to design and test manipulation strategies at nano-scale. Currently, the toolkit is capable of modeling the mechanistic interactions between an AFM tip and spherical particles on a substrate surface and generating optimum manipulation paths using a potential field approach. In addition, haptic fixtures were designed to guide the user to follow the calculated paths.Publication Metadata only Distributed management of service-enabled flow-paths across multiple SDN domains(IEEE, 2015) Civanlar, Seyhan; Lokman, Erhan; Kaytaz, Bülent; Department of Electrical and Electronics Engineering; Tekalp, Ahmet Murat; Faculty Member; Department of Electrical and Electronics Engineering; College of Engineering; 26207Future Internet may be comprised of interconnected multiple software-defined networks (SDN), where each domain is administered by a different controller or control plane. Provisioning of an end-to-end flow-path across such a network with specific service levels requires collaboration between domain controllers across control planes. A service-enabled flow-path shall be quality of service (QoS) enabled, reliable and/or secure, which requires a transport path with certain quantitative service level requirements such as high throughput, low packet loss, or high availability. Each SDN controller can autonomously determine such end-to-end flow-paths when all other SDN controllers periodically advertise to other controllers its available service-enabled paths. Doing so, each SDN controller is presented with several service-enabled path alternatives, crossing other domains, to choose from. We propose a multi-domain SDN controller design, wherein each SDN controller shares its network's "summarized" topology of service-enabled paths with other SDN controllers, such that all domains (controllers) have real-time autonomous decision making capability for end-to-end flow-path selection. We also describe how an SDN controller can reserve and release a flow traversing other SDN domains.Publication Metadata only Employing 60 GHz ISM band for 5G wireless communications(IEEE, 2014) Fadel, Etimad; N/A; Department of Electrical and Electronics Engineering; Yılmaz, Türker; Akan, Özgür Barış; PhD Student; Faculty Member; Department of Electrical and Electronics Engineering; Graduate School of Sciences and Engineering; College of Engineering; N/A; 6647Wireless data traffic is continuously increasing due to the steady rise in both connected device number and traffic per device. Wireless networks, traditionally confined below 6 giga-hertz, are getting clogged and unable to satisfy the ever-increasing demands of its users. Already aware of this, telecommunications industry and academia have been working on solutions. One of the main methods for throughput increase is operation bandwidth expansion; however, sufficient spectrum is not available within the conventional frequencies. Following various considerations, 60 GHz industrial, scientific and medical radio band has been selected as the new spectrum to be utilized and wireless personal and local area network standards for the band are already completed. In line with the stated developments, this paper proposes the use of 60 GHz band for the fifth generation (5G) communication systems. After very briefly setting the scene of the current wireless communication networks, the physical layer properties of the 60 GHz band are presented. A representative indoor simulation between the fourth generation and proposed 5G cases is set and performed. The results are assessed and compared before concluding the paper.Publication Open Access Investigating contributions of speech and facial landmarks for talking head generation(International Speech Communication Association (ISCA), 2021) N/A; Department of Computer Engineering; Kesim, Ege; Erzin, Engin; Faculty Member; Department of Computer Engineering; Graduate School of Sciences and Engineering; College of Engineering; N/A; 34503Talking head generation is an active research problem. It has been widely studied as a direct speech-to-video or two stage speech-to-landmarks-to-video mapping problem. In this study, our main motivation is to assess individual and joint contributions of the speech and facial landmarks to the talking head generation quality through a state-of-the-art generative adversarial network (GAN) architecture. Incorporating frame and sequence discriminators and a feature matching loss, we investigate performances of speech only, landmark only and joint speech and landmark driven talking head generation on the CREMA-D dataset. Objective evaluations using the peak signal-to-noise ratio (PSNR), structural similarity index (SSIM) and landmark distance (LMD) indicate that while landmarks bring PSNR and SSIM improvements to the speech driven system, speech brings LMD improvement to the landmark driven system. Furthermore, feature matching is observed to improve the speech driven talking head generation models significantly.Publication Metadata only Minimum length scheduling for wireless powered communication networks with discrete rates(IEEE, 2020) N/A; Department of Electrical and Electronics Engineering; Salık, Elif Dilek; Ergen, Sinem Çöleri; PhD Student; Faculty Member; Department of Electrical and Electronics Engineering; Graduate School of Sciences and Engineering; College of Engineering; N/A; 7211Radio frequency energy harvesting is an alternative solution to power the next generation wireless networks. the vast majority of the existing works focus on continuous rate transmission model, Although discrete rate model is more realistic for practical communication networks. We study the joint optimization of energy harvesting and information transmission times with the objective of minimizing the total schedule length of a multi-user, harvest-then-transmit, wireless powered communication network while following discrete Signal-to-Noise Ratio and rate transmission model. the users are required to transmit a minimum amount of data to the access point under a maximum transmit power limit. the formulated problem is mixed integer, non-linear and non-convex. First, we solve the case where the rate allocations are given. then, we exploit given rate allocation problem's optimality characteristics to achieve the global optimal solution for the original problem. We propose an exponential time optimal algorithm which exhibits practical superiority to the brute force algorithm, and two polynomial time heuristics, one of which prioritizes minimizing information transmission times, while the other focuses on improving energy harvesting time. Performances of the proposed algorithms are compared both to an algorithm which assigns continuous rates to the user, i.e., best lower bound, and to an algorithm which discretize the former continuous rate solution. Simulation results show that the proposed heuristic algorithms perform close to the optimal solution, and the proposed algorithms outperform the algorithm that discretize the continuous rate solution up to 56:9% for smaller access point power and 46:7% for higher number of users. This proves the importance of optimizing the total schedule length for discrete rate model as the users will be forced to transmit at discrete rates practically.Publication Metadata only Mixed and multi-precision SpMV for GPUs with row-wise precision selection(IEEE Computer Society, 2022) Kaya, Kamer; N/A; N/A; N/A; Department of Computer Engineering; Tezcan, Erhan; Torun, Tuğba; Koşar, Fahrican; Erten, Didem Unat; Master Student; Researcher; Master Student; Faculty Member; Department of Computer Engineering; Graduate School of Sciences and Engineering; N/A; Graduate School of Sciences and Engineering; College of Engineering; N/A; N/A; N/A; 219274Sparse Matrix-Vector Multiplication (SpMV) is one of the key memory-bound kernels commonly used in industrial and scientific applications. To improve its data movement and benefit from higher compute rates, there are several efforts to utilize mixed precision on SpMV. Most of the prior-art focus on performing the entire SpMV in single-precision within a bigger context of an iterative solver (e.g., CG, GMRES). In this work, we are interested in a more fine-grained mixed-precision SpMV, where the level of precision is decided for each element in the matrix to be used in a single operation. We extend an existing entry-wise precision based approach by deciding precisions per row, motivated by the granularity of parallelism on a GPU where groups of threads process rows in CSR-based matrices. We propose mixed-precision CSR storage methods with row permutations and describe their greater efficiency and load-balancing compared to the existing method. We also consider a multi-precision case where single and double precision copies of the matrix are stored priorly and further extend our mixed-precision SpMV approach to comply with it. As such, we leverage a mixed-precision SpMV to obtain a multi-precision Jacobi method which is faster than yet almost as accurate as double-precision Jacobi implementation, and further evaluate a multi-precision Cardiac modeling algorithm. We demonstrate the effectiveness of the proposed SpMV methods on an extensive dataset of real-valued large sparse matrices from the SuiteSparse Matrix Collection using an NVIDIA V100 GPU.Publication Metadata only Molecular channel model with multiple bit carrying molecules(IEEE, 2013) N/A; N/A; Department of Electrical and Electronics Engineering; Ünlütürk, Bige Deniz; Pehlivanoğlu, Ecehan Berk; Akan, Özgür Barış; PhD Student; PhD Student; Faculty Member; Department of Electrical and Electronics Engineering; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; College of Engineering; N/A; N/A; 6647Molecular communication is a bio-inspired paradigm, proposed to communicate nanomachines via diffusion of molecules through an aqueous medium. the type and structure of the molecules to be propagated bear great importance since they directly affect the modulation structure of molecular communication. We propose a messenger-based molecular communication model where information is encoded on the atoms of polyethylene molecules in the form of CH3(CHX)(n)CH2F, where X is either an H or F atom, representing 0 and 1 bits, respectively. the encoded polyethylene molecules are released from the transmitter nanomachine, and their propagation towards the receiver is modelled as a Brownian Motion. Using an erasure channel model, our analysis focuses on calculating the capacity of this channel and revealing the parameters affecting it such as molecule size and number of redundant molecules for one transmission.Publication Metadata only Vehicular VLC frequency domain channel sounding and characterization(IEEE, 2018) N/A; Department of Electrical and Electronics Engineering; Department of Electrical and Electronics Engineering; Turan, Buğra; Gürbilek, Gökhan; Uyrus, Ali; Ergen, Sinem Çöleri; PhD Student; Researcher; PhD Student; Faculty Member; Department of Electrical and Electronics Engineering; Graduate School of Sciences and Engineering; College of Engineering; Graduate School of Sciences and Engineering; College of Engineering; N/A; N/A; N/A; 7211Vehicular visible light communication (V2LC) has recently gained popularity as a complementary technology to radio frequency (RF) based vehicular communication schemes due to its low-cost, secure and RF-interference free nature. In this paper, we propose outdoor vehicular visible light communication (V2LC) frequency domain channel sounding based channel model characterization under night, sunset and sun conditions with the usage of vector network analyzer (VNA) and commercial off-the-shelf (COTS) automotive light emitting diode (LED) light. We further bring forward a new practical system bandwidth criterion named as effective usable bandwidth (EUB) for an end-to-end V2LC system with respect to the real world measurements. We demonstrate outdoor static V2LC channel measurement results, taking into account vehicle light emitting diode (LED) response, road reflections from nearby vehicles and various daylight conditions with respect to varying inter-vehicular distances. Measurement results indicate that, sunlight decreases system effective usable bandwidth due to the limited dynamic range of avalanche photodiode (APD), nearby vehicles cause constructive interference whereas road reflections change time dispersion characteristics of the V2LC channel.Publication Metadata only Visual and haptic simulation of linear viscoelastic tissue behavior based on experimental data(IEEE Computer Soc, 2006) N/A; N/A; Department of Mechanical Engineering; Sedef, Mert; Samur, Evren; Başdoğan, Çağatay; Master Student; Master Student; Faculty Member; Department of Mechanical Engineering; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; College of Engineering; N/A; 192890; 125489We have developed a new numerical scheme for simulating linear viscoelastic tissue behavior modeled by FEM. We have integrated experimentally-measured viscoelastic tissue properties into our model for realistic force feedback to the user. A new precomputation method based on superposition principle was proposed for real-time computation of nodal displacements and interaction forces. We achieved stable haptic interactions by executing the viscoelastic model at 100Hz while the haptic loop was updated at 1KHz. The developed model and the proposed pre-computation approach have been both validated using ANSYS.