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ÖgeAnalog neural network based on memristor crossbar arrays(İstanbul Teknik Üniversitesi, 2019) Yıldız, Hacer A. ; Altun, Mustafa ; Güngördü, Doğuş ; Stan, Mircea ; Elektronik ve Haberleşme Mühendisliği ; Electronics and Communications EngineeringIn this paper, a new feed forward analog neural network is designed using a memristor based crossbar array architecture. This structure consists of positive and negative polarity connection matrices. In order to show the performance and usefulness of the proposed circuit, it is considered a sample application of iris data recognition. The proposed neural network implementation is approved by the simulation in Cadence design environment using 0.35µm CMOS technology. The results obtained are promising for the implementation of high density neural network.
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ÖgeAntifungal Activities of Different Essential Oils and Their Electrospun Nanofibers against Aspergillus and Penicillium Species Isolated from Bread(American Chemical Society, 2022) Karbancıoğlu Güler, Funda ; Devecioğlu, Tuğba ; Türker, Mustafa ; 0000-0001-6576-0084 ; 0000-0001-6681-0944 ; Food EngineeringMold growth, especially Aspergillus spp. and Penicillium spp., deteriorates the quality of bakery products. Essential oils (EOs) have been categorized as good natural antimicrobials. Hereby, this study aimed to evaluate the antifungal activity of six EOs, ginger, cumin, cinnamon, black pepper, origanum, and clove, and their volatile compounds against fungal strains isolated from bread: Penicillium carneum DDS4, Aspergillus flavus DDS6, and Aspergillus niger DDS7 by disc diffusion and disc volatilization methods, respectively. Among EOs, cumin, cinnamon, origanum, and clove were found to be effective against fungal strains, and their minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC) were determined. The observed lowest MIC value of EOs was obtained at 1000 μg/mL concentration, and the lowest MFC value was obtained from the results of clove at a concentration of 1000 μg/mL. Based on the MIC and MFC values, clove and cinnamon EOs were found to be more effective at lower concentrations. Electrospun nanofiber films of clove and cinnamon were produced with 6% poly(vinyl alcohol) (PVA), 2% β-cyclodextrin (β-CD), and 2% EO to overcome the unfavorable sensory impact of EOs on food products. The inhibitory activity of cinnamon EO film (2.64–2.51 log(CFU/mg)) was considerably lower than clove EO film (3.18–3.24 log(CFU/mg)) against P. carneum DDS4 and A. niger DDS7. Furthermore, these nanofiber films prevented fungal growth on bread samples visibly and were shown to be an alternative application for active food packaging.
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ÖgeAppraising science-policy interfaces in local climate change policymaking: Revealing policymakers’ insights from Izmir Development Agency, Turkey(Elsevier, 2022) Eroğlu, Mehmet ; Öğüt Erbil, Aslı ; https://orcid.org/0000-0003-3127-8905 ; Department of SociologyDeveloping knowledge-based and usable climate change policies requires establishing science-policy interfaces through which knowledge producers and policymakers cooperate. Current research reveals that co-production- based interfaces dominated neither by knowledge producers nor policymakers succeed in facilitating the transformation of knowledge into politics. From this point of view, this paper explores how Izmir Development Agency (IZKA), a regional development agency in Turkey, utilizes scientific knowledge and science-policy interfaces in its activities on climate change. Based on the analysis of agency documents and semi-structured interviews with experts from and outside IZKA, the findings indicate that IZKA thrives in integrating scientific knowledge on climate change in its activities drawing from multi-stakeholder and multi-level science-policy interfaces that have significant similarities with the co-production model. In these interfaces, international, national, regional, and local stakeholders share their resources, knowledge, and experience on climate change. Although legal, geographical, and demographic conditions also have an impact, the main reason behind IZKA’s success is the agency’s climate-focused vision that shapes decisions, strategies, organizational structure, and activities. In parallel to the indicated finding, this paper also discloses that the perspective of not prioritizing climate change and considering the potential benefits as only “co-benefit” does not yield results with the desired efficiency. Another finding is that even though the national government is the main actor on climate in Turkey, development agencies are capable of carrying out transformative activities in their regions, albeit limited.
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ÖgeAssessment of geothermal power potential in Buyuk Menderes Basin, Turkey(Elsevier, 2020) Yamanlar, Şenol, ; Korkmaz Başel, Emine Didem ; Serpen, Ümran ; https://orcid.org/0000-0001-7713-9551 ; Petroleum and Natural Gas Engineering DepartmentTurkey’s installed geothermal capacity for power generation as of December 2019 is 1500 MWe. Most of this installed capacity is generated by the power plants located in the Buyuk Menderes graben. Geologically Buyuk Menderes graben is a huge structure having several discovered geothermal resources and can be considered as a geothermal basin. The aim of this study is to estimate the geothermal power potential of Buyuk Menderes graben. To achieve this object, a stochastic methodology, which is used to evaluate hydrocarbon-bearing basins, is adapted from the oil and natural gas industry. This methodology provides a way to quantify the geothermal potential in a range of possible values by evaluating the individual fields in the basin using stored heat technique. A total of 34 (21 proven and 13 probable occurrences) geothermal fields having medium to high temperature (T ≥ 100 °C) values are evaluated using the Monte Carlo Simulation technique. In these simulations, available geological, geochemical, geophysical data are used along with the data obtained from the drilled wells in the region. The power potential (MWe) values for 21 proven fields in terms of P10, P50 and P90 values are determined to be 888, 1077 and 1311 MWe, respectively. Considering the 13 probable occurrences along with the proven fields, the lower and upper limits of the total power potential (P10 and P90) are 1156 and 1580 MWe, respectively. Moreover, the power potentials are also evaluated under the presence of uncertainty. By assigning 5/13, 6/13, and 7/13 probability values for the 13 probable occurrences, overall geothermal power potential P10 values are estimated as 1041, 1075, and 1101 MWe, respectively.
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ÖgeAssessment of Microbial Diversity during Thermophilic Anaerobic Co-Digestion for an Effective Valorization of Food Waste and Wheat Straw( 2022-12-21) Yangın Gömeç, Çiğdem ; Agnihotri, Swarnima ; Ylitervo, Päivi ; Sárvári Horváth, Ilona ; 0000-0003-3519-4821 ; Environmental EngineeringIn this study, predominant bacterial and archaeal populations and their roles during anaerobic mono-digestion of food waste (FW) and co-digestion of FW with straw pellets (SP) at thermophilic temperature (53 ± 1 °C) were assessed by Next Generation Sequencing (NGS) analysis at organic loading rates (OLRs) of 3.0 and 7.0 gVS/L/d. Depending on the seed; results revealed that Firmicutes, Bacteroidetes, and Proteobacteria were, respectively the most prevalent bacterial phyla at both OLRs investigated. On the other hand, Euryarchaeota was dominated by methanogens playing crucial role in biogas production and correlated mainly with the activities of Methanobacteria and Methanomicrobia at class level. Acetoclastic Methanosaetae was the predominant genus at OLR = 3.0 gVS/L/d; however, shared the same predominance with hydrogenotrophic methanogens Methanospirillium at the highest OLR. Although no clear effect in response to straw addition at OLR of 3.0 gVS/L/d could be seen in terms of methanogenic archaea at genus level, hydrogenotrophic methanogens revealed some shift from Methanobacterium to Methanospirillium at higher OLR. Nevertheless, no prominent microbial shift in the presence of wheat straw at increased OLR was likely due to adapted inoculation at start-up which was also demonstrated by relatively stable biogas yields during co-digestion.
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ÖgeDefect Tolerant Logic Synthesis for Memristor Crossbars with Performance Evaluation(IEEE, 2018) Tunali, Onur ; Morgül, M. Ceylan ; Altun, Mustafa ; Elektronik ve Haberleşme Mühendisliği ; Electronics and Communication EngineeringIn this paper, we study defect-tolerant logic synthesis of memristor-based crossbar architectures. We propose a hybrid algorithm, combining heuristic and exact algorithms, that achieves perfect tolerance for 10-percent stuck-at open defect rates. Along with defect tolerance, we also consider area, delay, and power costs of the memristor crossbars to elaborate on two-level and multi-level logic designs.
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ÖgeElastic Stability of a Cylindrical Strip Subjected to Simple Bending(Bulletin of the Technical University of Istanbul, 1952-09-05) İnan, Mustafa ; Mustafa İnan Kütüphanesiİnan'ın "Bulletin of the Technical University of Istanbul, 1952, Cilt 5"de yayımlanan makalesi ve makalenin el yazması ile daktilo edilmiş hali.
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ÖgeEnergy Production from Biomass Valorization( 2023-05-24) Yangın Gömeç, Çiğdem ; Sárvári Horváth, Ilona ; Martin, Carlos ; 0000-0003-3519-4821 ; Environmental Engineering
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ÖgeA Fast Hill Climbing Algorithm for Defect and Variation Tolerant Logic Mapping of Nano-Crossbar Arrays(IEEE, 2018) Peker, Furkan ; Altun, Mustafa ; Elektronik ve Haberleşme Mühendisliği ; Electronics and Communication EngineeringNano-crossbar arrays are area and power efficient structures, generally realized with self-assembly based bottom-up fabrication methods as opposed to relatively costly traditional top-down lithography techniques. This advantage comes with a price: very high process variations. In this work, we focus on the worst-case delay optimization problem in the presence of high process variations. As a variation tolerant logic mapping scheme, a fast hill climbing algorithm is proposed; it offers similar or better delay improvements with much smaller runtimes compared to the methods in the literature. Our algorithm first performs a reducing operation for the crossbar motivated by the fact that the whole crossbar is not necessarily needed for the problem. This significantly decreases the computational load up to 72% percent for benchmark functions. Next, initial column mapping is applied. After the first two steps that can be considered as preparatory, the algorithm proceeds to the last step of hill climbing row search with column reordering where optimization for variation tolerance is performed. As an extension to this work, we directly apply our hill climbing algorithm on defective arrays to perform both defect and variation tolerance. Again, simulation results approve the speed of our algorithm, up to 600 times higher compared to the related algorithms in the literature without sacrificing defect and variation tolerance performance.
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ÖgeA fast logic mapping algorithm for multiple-type-defect tolerance in reconfigurable nano-crossbar arrays(Institute of Electrical and Electronics Engineers (IEEE), 2017-09-21) Tunali, Onur ; Altun, Mustafa ; https://orcid.org/0000-0002-3103-1809 ; Electronics and Communication EngineeringUnlike conventional CMOS circuits, nano-crossbar arrays have considerably high defect rates. Multiple-type defects randomly occur both on crosspoint switches and wires that substantially complicates the design phase of the circuits with an elimination of systematic design choices. In order to overcome this problem, a logic mapping methodology is presented in this paper. A fast heuristic algorithm using pre-mapping logic morphing, defect oriented adaptive sorting, matching with Hadamard multiplication, and backtracking is introduced. The proposed algorithm covers both crosspoint defects including stuck-open and stuck-closed types and wire defects including bridging and broken types. Effects of stuck-closed defects, mostly disregarded in the literature, are studied in depth. In simulations, an industrial benchmark suit is used for obtaining runtime and success rate values of the proposed algorithm in comparison with those of the existing algorithms in the literature. A relative accuracy evaluation is also given in comparison with exact mapping techniques. Finally, the steps of the algorithm that are based on pre-mapping and heuristic matching techniques, are separately justified with experimental results.
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ÖgeGeothermal boom in Turkey : growth in identified capacities and potentials(Elsevier, 2014) Korkmaz Başel, Emine Didem ; Serpen, Ümran ; Satman, Abdurrahman ; https://orcid.org/0000-0001-7713-9551 ; Petroleum and Natural Gas Engineering DepartmentIncreasing activities of geothermal development especially in the last three years result in a geothermal boom in Turkey. Not only the addition of new sites, but also updating the data of existing ones increased the currently identified capacity significantly. With the discoveries of 13 new geothermal fields, power potentials increased by 1.6 times. This study deals with hydrothermal and EGS potentials of Turkey. The geothermal resource base between 0 and 3 km depth in Turkey and the capacity of the currently identified 290 geothermal sites are determined to be 3.96 × 1023 J and 10,576 MWt, respectively. As of today, a total of 135 hydrothermal fields were individually studied, of which 38 medium to high temperature (T ≥ 100 °C) fields were simulated to estimate the power generation. The remaining 97 fields were simulated to estimate the direct use potentials. The lower and upper limits of power generation potential corresponding to P10 and P90 values are 1673 and 3140 MWe, respectively. Moreover, the lower and upper thermal potential limits of 135 hydrothermal fields corresponding to P10 and P90 values are 38.2 and 68.4 GWt, respectively.
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ÖgeGeothermal energy in Turkey: 2008 update(Elsevier, 2009) Serpen, Ümran ; Aksoy, Niyazi ; Öngür, Tahir ; Korkmaz Başel, Emine Didem ; https://orcid.org/0000-0001-7713-9551 ; Petroleum and Natural Gas Engineering DepartmentGeological studies indicate that the most important geothermal systems of western Turkey are located in the major grabens of the Menderes Metamorphic Massif, while those that are associated with local volcanism are more common in the central and eastern parts of the country. The present (2008) installed geothermal power generation capacity in Turkey is about 32.65 MWe, while that of direct use projects is around 795 MWt. Eleven major, high-to-medium enthalpy fields in western part of the country have 570 MWe of proven, 905 MWe of probable and 1389 MWe of possible geothermal reserves for power generation. In spite of the complex legal issues related to the development of Turkey's geothermal resources, their use is expected to increase in the future, particularly for electricity generation and for greenhouse heating.
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ÖgeIn vivo dielectric properties of healthy and benign rat mammary tissues from 500 MHz to 18 GHz(MDPI, 2020-04) Yılmaz, Tuba ; Ateş Alkan, Fatma ; Elektronik ve Haberleşme Mühendisliği ; Electronics and Communication EngineeringThis work investigates the in vivo dielectric properties of healthy and benign rat mammary tissues in an attempt to expand the dielectric property knowledge of animal models. The outcomes of this study can enable testing of microwave medical technologies on animal models and interpretation of tissue alteration-dependent in vivo dielectric properties of mammary tissues. Towards this end, in vivo dielectric properties of healthy rat mammary tissues and chemically induced benign rat mammary tumors including low-grade adenosis, sclerosing adenosis, and adenosis were collected with open-ended coaxial probes from 500 MHz to 18 GHz. The in vivo measurements revealed that the dielectric properties of benign rat mammary tumors are higher than the healthy rat mammary tissues by 9.3% to 35.5% and 19.6% to 48.7% for relative permittivity and conductivity, respectively. Furthermore, to our surprise, we found that the grade of the benign tissue affects the dielectric properties for this study. Finally, a comparison with ex vivo healthy human mammary tissue dielectric properties revealed that the healthy rat mammary tissues best replicate the dielectric properties of healthy medium density human samples.
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Öge"İnsan ve Otomat" başlıklı makale( 1966-02-09) İnan, Mustafa ; Mustafa İnan Kütüphanesiİnan'ın, İ.T.Ü. Elektronik Hesap Merkezi tarafından düzenlenen Elektronik Hesap Seminerinde, 8 Eylül 1965 tarihinde sunduğu bildiri metnidir.
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ÖgeK Dergisi'nde yayımlanmış Oğuz Atay üzerine bir yazı(K Dergisi, 2007-08-17) Yılmazçelik, Cansu ; Mustafa İnan KütüphanesiK Dergisi'nin 17.08.2007 tarihli 46. sayısında yayımlanmış Oğuz Atay üzerine bir yazı. Yazının içinde Bir Bilim Adamının Romanı: Mustafa İnan kitabına da değiniliyor.
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ÖgeLogic Synthesis and Testing Techniques for Switching Nano-Crossbar Arrays(Elsevier, 2017) Alexandrescua, Dan ; Altun, Mustafa ; Anghel, Lorena ; Bernasconi, Anna ; Cirianie, Valentina ; Frontini, Luca ; Tahoori, Mehdi ; Elektronik ve Haberleşme Mühendisliği ; Electronics and Communication EngineeringBeyond CMOS, new technologies are emerging to extend electronic systems with features unavailable to silicon-based devices. Emerging technologies provide new logic and interconnection structures for computation, storage and communication that may require new design paradigms, and therefore trigger the development of a new generation of design automation tools. In the last decade, several emerging technologies have been proposed and the time has come for studying new ad-hoc techniques and tools for logic synthesis, physical design and testing. The main goal of this project is developing a complete synthesis and optimization methodology for switching nano-crossbar arrays that leads to the design and construction of an emerging nanocomputer. New models for diode, FET, and four-terminal switch based nanoarrays are developed. The proposed methodology implements logic, arithmetic, and memory elements by considering performance parameters such as area, delay, power dissipation, and reliability. With combination of logic, arithmetic, and memory elements a synchronous state machine (SSM), representation of a computer, is realized. The proposed methodology targets variety of emerging technologies including nanowire/nanotube crossbar arrays, magnetic switch-based structures, and crossbar memories. The results of this project will be a foundation of nano-crossbar based circuit design techniques and greatly contribute to the construction of emerging computers beyond CMOS. The topic of this project can be considered under the research area of “Emerging Computing Models” or “Computational Nanoelectronics”, more specifically the design, modeling, and simulation of new nanoscale switches beyond CMOS.
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ÖgeMicrowave dielectric property based classification of renal calculi: Application of a kNN algorithm(Elsevier, 2019) Saçlı, Banu ; Aydınalp, Cemanur ; Cansız, Gökhan ; joof, Sulayman ; Yılmaz, Tuba ; Çayören, Mehmet ; Önal, Bülent ; Akduman, İbrahim ; Elektronik ve Haberleşme Mühendisliği ; Electronics and Communication EngineeringThe proper management of renal lithiasis presents a challenge, with the recur- rence rate of the disease being as high as 46%. To prevent recurrence, the first step is the accurate categorization of the discarded renal calculi. Currently, the discarded renal calculi type is determined with the X-ray powder diffraction method which requires a cumbersome sample preparation. This work presents a new approach that can enable fast and accurate classification of discarded renal calculi with minimal sample preparation requirements. To do so, first, the measurements of the dielectric properties of naturally formed renal calculi are collected with the open-ended contact probe technique between 500 MHz to 6 GHz with 100 MHz intervals. Cole–Cole parameters are fitted to the measured dielectric properties with the generalized Newton–Raphson method. The re- nal calculi types are classified based on their Cole–Cole parameters as calcium oxalate, cystine, or struvite. The classification is performed using nearest neigh- bors (kNN) machine learning algorithm with the 10 nearest neighbors, where accuracy as high as 98.17% is achieved.
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ÖgeMicrowave dielectric spectroscopy of renal calculi: A large scale study on dielectric properties from 500 MHz to 18 GHz(IEEE, 2019) Yılmaz, Tuba ; Saçlı, Banu ; Cansız, Gökhan ; joof, Sulayman ; Aydınalp, Cemanur ; Çayören, Mehmet ; Akduman, İbrahim ; Önal, Bülent ; Elektronik ve Haberleşme Mühendisliği ; Electronics and Communication EngineeringInherent dielectric property discrepancy between biological anomalies and healthy tissue enables the microwave diagnostic and therapeutic technologies. To reveal this discrepancy, microwave dielectric properties of many different biological tissues are tabulated. Although the dielectric properties of biological tissues are well documented in the literature, the knowledge on microwave dielectric property behavior of the renal calculi is limited. This work presents ultra wideband dielectric properties of three renal calculi types between 500 MHz to 18 GHz to pave the way for possible application of microwave technologies for diagnosis, treatment, and prevention of urolithiasis. Microwave dielectric spectroscopy is performed on a total of 66 natural stone samples with open-ended coaxial probe technique. The samples belong to three commonly diagnosed renal calculi categories, namely calcium oxalate, cystine, struvite. Analysis of variance (ANOVA) test is performed on fitted Cole-Cole parameters and it was concluded that there is a statistically significant difference between the dielectric properties of the renal calculi types. A patient-to-patient statistical test is also performed and it was concluded that there is no statistical difference between the samples belonging to the same renal calculi category. To this end, based on the relative permittivity discrepancy between the renal calculi types, the category of renal calculi can be identified by measuring the dielectric properties of renal calculi with open-ended coaxial probe technique.
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ÖgeMicrowave spectroscopy based classification of rat hepatic tissues: On the significance of dataset(BAJECE, 2020-10) 0000-0003-3052-2945 ; Elektronik ve Haberleşme MühendisliğiWith the advancements in machine learning (ML) algorithms, microwave dielectric spectroscopy emerged as a potential new technology for biological tissue and material categorization. Recent studies reported the successful utilization of dielectric properties and Cole-Cole parameters. However, the role of the dataset was not investigated. Particularly, both dielectric properties and Cole-Cole parameters are derived from the S parameter response. This work investigates the possibility of using S parameters as a dataset to categorize the rat hepatic tissues into cirrhosis, malignant, and healthy categories. Using S parameters can potentially remove the need to derive the dielectric properties and enable the utilization of microwave structures such as narrow or wideband antennas or resonators. To this end, in vivo dielectric properties and S parameters collected from hepatic tissues were classified using logistic regression (LR) and adaptive boosting (AdaBoost) algorithms. Cole-Cole parameters and a reproduced dielectric property data set were also investigated. Data preprocessing is performed by using standardization a principal component analysis (PCA). Using the AdaBoost algorithm over 93% and 88% accuracy is obtained for dielectric properties and S parameters, respectively. These results indicate that the classification can be performed with a 5% accuracy decrease indicating that S parameters can be an alternative dataset for tissue classification.
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ÖgeMimoza : İTÜ Bilim, Mühendislik ve Teknolojide Kadın Araştırmaları ve Uygulamaları Merkezi Dergisi(İTÜ Yayınevi, 2024-01) Mimoza ; İTÜ YayıneviMimoza dergisi, Merkezimizin Aralık 2014 tarihinden itibaren yılda iki sayı olarak yayınlanan sürekli yayınıdır. Dergimiz Merkez Müdürümüz Prof. Dr. Fatma ARSLAN (2013-2017) döneminde yayın hayatına başlamış ve ilk 6 sayısını yine bu dönemde, 7. sayısını ise Prof. Dr. L. Figen GÜL (2019-2022) yürütücülüğünde okuyucuya basılı olarak sunmuştur. Derginin Ocak 2024 tarihli 8. Sayısının 250. Yıl Hatıra Sayısı olarak İTÜ Yayınevi bünyesinde e-dergi ve basılı olarak yayınlanmasına karar verilmiştir. Derginin bu özel sayısı, Türkiye Cumhuriyetimizin 100., Üniversitemizin 250. Yılında geliştirilen etkinlik ve yayın külliyatına kadın araştırmalarını önceleyen içeriği ile katkı vermeyi amaçlamaktadır. Derginin bu özel sayısında 250 yıllık bir eğitim çınarı olan üniversitemizin özellikle 1773- 2023 yılları arasındaki serüvenini öne çıkartan uluslararası ve ulusal motivasyonu belgeleyen basılı ve görsel envantere dayalı kitaplar, belgeseller ve etkinlikleri İTÜ İletişim Direktörü Adem DÖNMEZ tarafından özetlenmiştir. Üniversitemizin sürdürülebilirlik çalışmaları ve derecelendirme süreçlerindeki başarısı İTÜ Sürdürülebilirlik Ofisi Koordinatörü Doç.Dr. Börte KÖSE