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Permanent URI for this collectionhttps://hdl.handle.net/20.500.14288/3
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Publication Metadata only Vilma: a zero-shot benchmark for linguıstic and temporal grounding in video-language models(International Conference on Learning Representations, ICLR, 2024) Pedrotti, Andrea; Dogan, Mustafa; Cafagna, Michele; Parcalabescu, Letitia; Calixto, Iacer; Frank, Anetteh; Gatt, Albert; Department of Electrical and Electronics Engineering; Kesen, İlker; Erdem, Aykut; Department of Electrical and Electronics Engineering; Koç Üniversitesi İş Bankası Yapay Zeka Uygulama ve Araştırma Merkezi (KUIS AI)/ Koç University İş Bank Artificial Intelligence Center (KUIS AI); Graduate School of Sciences and Engineering; College of EngineeringWith the ever-increasing popularity of pretrained Video-Language Models (VidLMs), there is a pressing need to develop robust evaluation methodologies that delve deeper into their visio-linguistic capabilities. To address this challenge, we present VILMA), a task-agnostic benchmark that places the assessment of fine-grained capabilities of these models on a firm footing. Task-based evaluations, while valuable, fail to capture the complexities and specific temporal aspects of moving images that VidLMs need to process. Through carefully curated counterfactuals, VILMA offers a controlled evaluation suite that sheds light on the true potential of these models, as well as their performance gaps compared to human-level understanding. VILMA also includes proficiency tests, which assess basic capabilities deemed essential to solving the main counterfactual tests. We show that current VidLMs' grounding abilities are no better than those of vision-language models which use static images. This is especially striking once the performance on proficiency tests is factored in. Our benchmark serves as a catalyst for future research on VidLMs, helping to highlight areas that still need to be explored.Publication Metadata only Improving defocus blur in holographic displays(John Wiley and Sons Inc, 2023) Itoh, Yuta; Akşit, Kaan; Department of Electrical and Electronics Engineering; Kavaklı, Koray; Ürey, Hakan; Department of Electrical and Electronics Engineering; Graduate School of Sciences and Engineering; College of EngineeringIn this paper we present a novel multiplane computer generated hologram calculation approach that enables artifact free and realistic-looking defocus blur for optical reconstructions in a holographic display. We introduce a new targeting method and a loss function that evaluates the focused and defocused parts of the reconstructed images. We demonstrate that our method is applicable to various standard hologram generation routines such for both iterative and non-iterative CGH calculation methods. We also demonstrate our new gradient descent-based optimization with double phase constraint combined with our targeting scheme and loss function provides the best image quality. We validate our findings for both the numerical reconstructions and optical captures that are acquired from our holographic display prototype. © 2023, John Wiley and Sons Inc. All rights reserved.Publication Metadata only Exploring projection based mixed reality with tangibles for nonsymbolic preschool math education(Assoc Computing Machinery, 2019) N/A; N/A; Department of Psychology; Department of Media and Visual Arts; Department of Electrical and Electronics Engineering; Salman, Elif; Beşevli, Ceylan; Göksun, Tilbe; Özcan, Oğuzhan; Ürey, Hakan; Master Student; Researcher; Faculty Member; Faculty Member; Faculty Member; Department of Psychology; Department of Media and Visual Arts; Department of Electrical and Electronics Engineering; Graduate School of Sciences and Engineering; Graduate School of Social Sciences and Humanities; College of Social Sciences and Humanities; College of Social Sciences and Humanities; College of Engineering; N/A; N/A; 47278; 12532; 8579A child's early math development can stem from interactions with the physical world. Accordingly, current tangible interaction studies focus on preschool children's formal (symbolic) mathematics, i.e. number knowledge. However, recent developmental studies stress the importance of nonsymbolic number representation in math learning, i.e. understanding quantity relations without counting(more/less). To our knowledge, there are no tangible systems based on this math concept. We developed an initial tangible based mixed-reality(MR) setup with a small tabletop projector and depth camera. Our goal was observing children's interaction with the setup to guide our further design process towards developing nonsymbolic math trainings. In this paper we present our observations from sessions with four 3-to-5 year old children and discuss their meaning for future work. Initial clues show that our MR setup leads to exploratory and mindful interactions, which might be generalizable to other tangible MR systems for child education and could inspire interaction design studies.Publication Metadata only Engine compartment UWB channel model for intravehicular wireless sensor networks(IEEE-Inst Electrical Electronics Engineers Inc, 2014) Department of Computer Engineering; N/A; Department of Electrical and Electronics Engineering; Demir, Utku; Baş, Celalettin Ümit; Ergen, Sinem Çöleri; Undergraduate Student; Master Student; Faculty Member; Department of Computer Engineering; Department of Electrical and Electronics Engineering; College of Engineering; Graduate School of Sciences and Engineering; College of Engineering; N/A; N/A; 7211Intravehicular wireless sensor network (IVWSN) is a cutting edge research topic that delivers cost reduction, assembly, and maintenance efficiency by removing the wiring harnesses within the vehicle and enables the integration of new sensors into the locations inside a vehicle where cable connection is not possible. Providing energy efficiency through the low-duty-cycle operation and high reliability by exploiting the large bandwidth, ultrawideband (UWB) has been determined to be the most appropriate technology for IVWSNs. We investigate the UWB channel model for IVWSNs within the engine compartment of a vehicle by collecting an extensive amount of data for 19 x 19 links for different types and conditions of the vehicle. These include a Fiat Linea with engine off, Fiat Linea with engine on, and Peugeot Bipper with engine off. The path-loss exponent is estimated to be around 3.5 without exhibiting much variation when the engine is turned on and for different types of vehicles. The power variation around the expected path loss has lognormal distribution with zero mean and standard deviation in the range of [5.5, 6.3] dB for different types of vehicles with almost no variation when the engine of the same vehicle is turned on. The clustering phenomenon in the power delay profile (PDP) is well represented by a modified Saleh-Valenzuela (SV) model. The interarrival times of the clusters are modeled using a Weibull distribution. The cluster-amplitude and ray-amplitude decay functions are represented with a dual-slope linear model with breakpoint around 26.6 and 5.5 ns, respectively. The parameters of the Weibull distribution and these dual-slope linear models do not vary significantly for different types and conditions of the vehicle. The variations of the observed PDPs around the SV model is well modeled by independent normal random variables with zero mean and with a variance independent of the delay bin, and the type and condition of the vehicle. We propose a simulation model for the UWB channel within the engine compartment based on these findings and validate it by comparing the received energy and root mean square (RMS) delay spread of the generated and observed PDPs.Publication Metadata only Toward interdisciplinary synergies in molecular communications: perspectives from synthetic biology, nanotechnology, communications engineering and philosophy of science(Multidisciplinary Digital Publishing Institute (MDPI), 2023) Egan, Malcolm; Barros, Michael Taynnan; Booth, Michael; Llopis-Lorente, Antoni; Magarini, Maurizio; Martins, Daniel P.; Schäfer, Maximilian; Stano, Pasquale; Department of Electrical and Electronics Engineering; Kuşcu, Murat; Faculty Member; Department of Electrical and Electronics Engineering; College of Engineering; 316349Within many chemical and biological systems, both synthetic and natural, communication via chemical messengers is widely viewed as a key feature. Often known as molecular communication, such communication has been a concern in the fields of synthetic biologists, nanotechnologists, communications engineers, and philosophers of science. However, interactions between these fields are currently limited. Nevertheless, the fact that the same basic phenomenon is studied by all of these fields raises the question of whether there are unexploited interdisciplinary synergies. In this paper, we summarize the perspectives of each field on molecular communications, highlight potential synergies, discuss ongoing challenges to exploit these synergies, and present future perspectives for interdisciplinary efforts in this area.Publication Metadata only Wide-field-of-view dual-focal-plane augmented reality display(Spie-Int Soc Optical Engineering, 2019) N/A; N/A; N/A; Department of Electrical and Electronics Engineering; Başak, Uğur Yekta; Kazempourradi, Seyedmahdi; Ulusoy, Erdem; Ürey, Hakan; Master Student; PhD Student; Resercher; Faculty Member; Department of Electrical and Electronics Engineering; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; N/A; College of Engineering; N/A; N/A; N/A; 8579Stereoscopic augmented reality (AR) displays with a fixed focus plane suffer from visual discomfort due to vergence-accommodation conflict (VAC). In this study, we propose a biocular dual-focal plane AR system. Two separate liquid crystal displays (LCDs) are placed at slightly different distances to a Fresnel relay lens such that virtual images of LCDs appear at 25 cm and 50 cm to the user. Both LCDs are totally viewed by both eyes, such that the rendered images are not parallax images for each eye. While the system is limited to two depths, it provides correct focus cues and natural blur effect in two distinct depths. This allows the user to distinguish virtual information, even when the virtual objects overlap and partially occlude in the axial direction. Displays are driven by a single computation unit and the objects in the virtual scene are distributed over the LCDs according to their depths. Field-of-view is 60 x 36 degrees and the eye-box is larger than 100 mm, which is comfortable enough for two-eye viewing.Publication Metadata only Biocompatibility and neural stimulation capacity of aluminum antimonide nanocrystals biointerfaces for use in artificial vision(Association for Research in Vision and Ophthalmology (ARVO), 2021) N/A; N/A; N/A; N/A; N/A; N/A; N/A; Department of Electrical and Electronics Engineering; N/A; Kesim, Cem; Han, Mertcan; Yıldız, Erdost; Jalali, Houman Bahmani; Qureshi, Mohammad Haroon; Hasanreisoğlu, Murat; Nizamoğlu, Sedat; Şahin, Afsun; Doctor; Master Student; PhD Student; PhD Student; PhD Student; Faculty Member; Faculty Member; Faculty Member; Department of Electrical and Electronics Engineering; Koç University Research Center for Translational Medicine (KUTTAM) / Koç Üniversitesi Translasyonel Tıp Araştırma Merkezi (KUTTAM); N/A; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; School of Medicine; College of Engineering; School of Medicine; Koç University Hospital; N/A; N/A; N/A; N/A; N/A; N/A; N/A; 387367; N/A; N/A; N/A; N/A; 182001; 130295; 71267N/APublication Metadata only Ultra-efficient and high-quality white light-emitting devices using fluorescent proteins in aqueous medium(Wiley, 2020) N/A; N/A; N/A; Department of Molecular Biology and Genetics; Department of Electrical and Electronics Engineering; Sadeghi, Sadra; Melikov, Rustamzhon; Çonkar, Deniz; Karalar, Elif Nur Fırat; Nizamoğlu, Sedat; PhD Student; PhD Student; PhD Student; Faculty Member; Faculty Member; Department of Molecular Biology and Genetics; Department of Electrical and Electronics Engineering; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; College of Sciences; College of Engineering; N/A; N/A; N/A; 206349; 130295The transformation of electronics toward “green” and efficient devices is critical for the environmental sustainability and energy future. So far, majority of efficient lighting devices have been realized by artificial optical materials such as rare-earth-elements-doped phosphors, colloidal quantum dots (QDs) and dyes. In this study, red-emitting mScarlet and green-emitting eGFP fluorescent proteins are determined for high-performance white LEDs, expressed in living Escherichia coli and the purified proteins are integrated in their natural aqueous environment onto blue LED chips. The aqueous integration preserved quantum yield levels of the proteins above 70% in the device architecture and facilitated a high luminous efficiency (LE) of 81 lm W−1 with a color rendering index (CRI) of 83, which is the most efficient eco-friendly white LED reported to date. Moreover, the concentration ratio are also optimized of red- and green-emitting proteins and white protein-based LEDs with a maximum CRI of 92 are demonstrated. This study shows that fluorescent proteins hold great promise for the next generation eco-friendly, efficient and high-quality white light sources.Publication Metadata only Adaptation strategies for MGS scalable video streaming(Elsevier, 2012) N/A; Department of Electrical and Electronics Engineering; Görkemli, Burak; Tekalp, Ahmet Murat; N/A; Faculty Member; Department of Electrical and Electronics Engineering; College of Engineering; College of Engineering; N/A; 26207An adaptive streaming framework consists of a video codec that can produce video encoded at a variety of rates, a transport protocol that supports an effective rate/congestion control mechanism, and an adaptation strategy in order to match the video source rate to the available network throughput. The main parameters of the adaptation strategy are encoder configuration, video extraction method, determination of video extraction rate, send rate control, retransmission of lost packets, decoder buffer status, and packetization method. This paper proposes optimal adaptation strategies, in terms of received video quality and used network resources, at the codec and network levels using a medium grain scalable (MGS) video codec and two transport protocols with built-in congestion control, TCP and DCCP. Key recommendations are presented to obtain the best results in adaptive video streaming using TCP or DCCP based on extensive experimental results over the Internet. (c) 2012 Elsevier B.V. All rights reserved.Publication Metadata only Ecofriendly and efficient luminescent solar concentrators based on fluorescent proteins(amer Chemical Soc, 2019) N/A; N/A; N/A; N/A; Department of Electrical and Electronics Engineering; N/A; Department of Molecular Biology and Genetics; Department of Electrical and Electronics Engineering; Sadeghi, Sadra; Melikov, Rustamzhon; Jalali, Houman Bahmani; Karatüm, Onuralp; Srivastava, Shashi Bhushan; Çonkar, Deniz; Karalar, Elif Nur Fırat; Nizamoğlu, Sedat; PhD Student; PhD Student; PhD Student; PhD Student; Researcher; PhD Student; Faculty Member, Faculty Member; Department of Molecular Biology and Genetics; Department of Electrical and Electronics Engineering; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; College of Engineering; Graduate School of Sciences and Engineering; College of Sciences; College of Engineering; N/A; N/A; N/A; N/A; N/A; N/A; 206349; 130295In recent years, luminescent solar concentrators (LSCs) have received renewed attention as a versatile platform for large-area, high-efficiency, and low-cost solar energy harvesting. So far, artificial or engineered optical materials, such as rare-earth ions, organic dyes, and colloidal quantum dots (QDs) have been incorporated into LSCs. Incorporation of nontoxic materials into efficient device architectures is critical for environmental sustainability and clean energy production. Here, we demonstrated LSCs based on fluorescent proteins, which are biologically produced, ecofriendly, and edible luminescent biomaterials along with exceptional optical properties. We synthesized mScarlet fluorescent proteins in Escherichia coli expression system, which is the brightest protein with a quantum yield of 61% in red spectral region that matches well with the spectral response of silicon solar cells. Moreover, we integrated fluorescent proteins in an aqueous medium into solar concentrators, which preserved their quantum efficiency in LSCs and separated luminescence and wave-guiding regions due to refractive index contrast for efficient energy harvesting. Solar concentrators based on mScarlet fluorescent proteins achieved an external LSC efficiency of 2.58%, and the integration at high concentrations increased their efficiency approaching to 5%, which may facilitate their use as “luminescent solar curtains” for in-house applications. The liquid-state integration of proteins paves a way toward efficient and “green” solar energy harvesting.