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Design and Experimental Demonstration of an Integrated Sensing and Communication System for Vital Sign Detection
Get PDFThe identification of vital signs is becoming increasingly important in various applications, including healthcare monitoring, security, smart homes, and locating entrapped persons after disastrous events, most of which are achieved using continuous-wave radars and ultra-wideband systems. Operating frequency and transmission power are important factors to consider when conducting earthquake search and rescue (SAR) operations in urban regions. Poor communication infrastructure can also impede SAR operations. This study proposes a method for vital sign detection using an integrated sensing and communication (ISAC) system where a unified orthogonal frequency division multiplexing (OFDM) signal was adopted, and it is capable of sensing life signs and carrying out communication simultaneously. An ISAC demonstration system based on software-defined radios (SDRs) was initiated to detect respiratory and heartbeat rates while maintaining communication capability in a typical office environment. The specially designed OFDM signals were transmitted, reflected from a human subject, received, and processed to estimate the micro-Doppler effect induced by the breathing and heartbeat of the human in the environment. According to the results, vital signs, including respiration and heartbeat rates, have been accurately detected by post-processing the reflected OFDM signals with a 1 MHz bandwidth, confirmed with conventional contact-based detection approaches. The potential of dual-function capability of OFDM signals for sensing purposes has been verified. The principle and method developed can be applied in wider ISAC systems for search and rescue purposes while maintaining communication links
Generalized variational autoencoders for learning disentangled representation
No full textThe major goal of disentangled representation learning is to form representation space, which independently captures the underlying sources of variation, responsible for generating the data. A pioneering approach is suggested under the group of methods based on Autoencoders (AE), such as, Variational Autoencoders (VAE), β-Variational Autoencoders (β-VAE), σ-VAE, Control-VAE, Dynamic-VAE and Learnable-VAE (L-VAE). These methods incorporate a disentanglement term, mostly expressed as a Kullback–Leibler Divergence and several hyperparameters and regularization terms in the loss function. These methods assume an equal disentanglement degree for the sources in different dimensions of the representation by using an empirically adjusted and fixed β parameter (β=0 or ≥1) across all dimensions. However, given the unobservable nature of the data-generating process and potential entanglements of different sources, we expect that distinct dimensions of the learned representation should exhibit varying degrees of disentanglement. In this study, we generalize the variational autoencoders and its variants by introducing a set of flexible weight functions and regularization terms for different dimensions. This generalization enables us to disentangle each latent dimension by learning the weight function of each dimension, independently. We also propose a special case of generalized VAE, called Multidimensional Learnable Variational Autoencoders, (mdL-VAE), which provide a better disentanglement-reconstruction trade-off without empirically tuning the hyperparameters of the loss function. The learned weight functions of mdL-VAE provide us useful insights about the degree of entanglement among the underlying factors of variation
Flexibility Management Through a Sensitivity Matrix for Ring Operated Power Distribution Systems
No full textThe increasing penetration of renewable energy sources and flexible loads, such as electric vehicles, is reshaping the operational strategies of distribution system operators (DSOs). To address these rapid and dynamic changes, DSOs must adopt innovative methods for maintaining system stability and efficiency. This paper introduces an analytical approach for managing overloaded lines in ring-operated power distribution systems by optimizing the operation of flexible loads and generation units. The method leverages a sensitivity matrix derived from the system topology to determine optimal set points for flexible resources, ensuring that branch currents are adjusted to achieve desired operational outcomes. Simulation results highlight the effectiveness of the proposed method in enhancing system performance under dynamic conditions
Investigation of potential dark sky parks in Southwestern Türkiye
No full textThe TR61 province in Türkiye, which includes the cities of Antalya, Burdur, and Isparta, was chosen as the study area. Long-term (2012–2022) Artificial Light (AL) data from VIIRS on the Suomi-NPP satellite, along with cloud cover and elevation data, were analyzed in a GIS environment. The study identified 84 potential IDSP areas, concentrated mainly in Manavgat, İbradı, and Akseki. The largest site spans 1,180 hectares, while the darkest shows a sky brightness of 21.57 mag arcsec−2. Köprülü Canyon National Park, with 14 potential areas, was selected as the primary IDSP candidate. The measured AL values were consistent with the site selection, confirming the accuracy of the identified areas. Ground-based SQM observations in two regions of the park validated the satellite-derived AL data. Ongoing monitoring and the use of simple GIS techniques with available satellite data are recommended for future IDSP site selection and classification
Antibakteriyel Yara Örtüsü Uygulamaları İçin Gentamisin Yüklü İpek Fibroin/Karbon Nanofiber Kompozitinin Geliştirilmesi
No full textHealing of chronic wounds remains a global healthcare challenge with profound socioeconomic implications. Addressing this issue requires advanced wound dressings combining biocompatibility, mechanical strength, moisture retention, and effective microbial protection. For this purpose, gentamicin-loaded porous silk fibroin (SF)–carbon nanofiber (CNF) composite dressings were developed. SF, a natural biocompatible polymer, provides a favorable environment for tissue regeneration, while CNF enhances mechanical strength without adverse tissue responses. The porous architecture facilitates antibiotic loading, moisture retention, and gas exchange, promoting healing. Dressings were fabricated via salt-leaching, followed by gentamicin loading to prevent bacterial colonization. Porosity and morphology were examined using scanning electron microscopy (SEM). CNF incorporation was confirmed by peak shifts in X-ray diffraction (XRD) patterns, while the β-sheet structure of SF was characterized by XRD and Fourier-transform infrared spectroscopy (FTIR). CNF integration resulted in a two-fold tensile strength increase, and the dressings exhibited ~600% swelling ratio. Gentamicin loading and release kinetics were quantified using UV–Vis spectroscopy following the gentamicin–OPA reaction. Cytocompatibility was assessed by seeding human keratinocyte (HaCaT) cells on the dressings and evaluating proliferation via MTT assay. Cell migration studies showed no negative effect on keratinocyte migration. Antibacterial testing demonstrated efficacy against Gram-negative Escherichia coli for up to 4 days and Gram-positive Staphylococcus aureus for up to 7 days, with biofilm biomass reduced by ~50% in both strains. These results highlight gentamicin-loaded SF–CNF composite dressings as a multifunctional strategy for promoting wound healing and preventing infection in chronic wounds.Kronik yaraların iyileştirilmesi, hastalar ve sağlık ekonomileri açısından küresel geniş etkileri olan bir sorundur. Çözüm olarak geliştirilmiş yara örtülerine ihtiyaç duyulmaktadır. Bu yara örtüleri biyouyumlu olmalı ve yara dokusuna mekanik olarak uygun özellikler göstermelidir. Ayrıca nem dengesini korumalı, gaz alışverişine izin vermeli ve patojenlere karşı koruma sağlamalıdır. Bu hedefe yönelik, gentamisin yüklü gözenekli ipek fibroin (SF)/karbon nanofiber (CNF) kompozit yara örtüleri tasarlanmıştır. SF, doğal ve biyouyumlu bir polimerdir, CNF ise olumsuz doku reaksiyonlarına yol açmadan mekanik dayanımı artırır. Bununla birlikte, gözenek yapısı antibiyotik yükleme kapasitesini arttırır, nem tutma özelliğini ve gaz alışverişini olumlu etkiler. Örtülere yüklenen gentamisin, yara bölgesinde olası bakteri kolonizasyonunu engeller. Bu tezde, örtüler tuz çözündürme yöntemiyle üretilmiştir. Gözenek yapısını incelemek için Taramalı Elektron Mikroskobu (SEM) kullanılmıştır. CNF ilavesi X-Işını Difraksiyonu (XRD) analizinde gözlenen tepe kayması ile görülmüştür. İpek fibroinin beta-pileli yapısı XRD ve Fourier Dönüşümlü Kızılötesi Spektroskopisi (FTIR) ile karakterize edilmiştir. CNF katkısı, sadece SF kullanılan örneklere kıyasla çekme dayanımını iki katına çıkarmıştır. Ek olarak, yara örtülerinde %600 şişme kapasitesi gözlenmiştir. Bunların yanı sıra, ilaç yükleme ve salım davranışı UV-Vis spektroskopisiyle Gentamisin-OPA reaksiyonu kullanılarak analiz edilmiştir. İlaveten, insan keratinosit hücreleri (HACAT) ile yapılan in vitro testlerde proliferasyon MTT testiyle değerlendirilmiş ve hücre göçü üzerine engelleyici etki olmadığı saptanmıştır. Bunun yanında, örtüler Escherichia coli'ye karşı 4 gün ve Staphylococcus aureus'a karşı 7 gün süreyle antibakteriyel etki göstermiştir. Dahası her iki bakteri türünde de biyofilm kütlesini yarıya indirmiştir. Bu sonuçlar, antibakteriyel SF-CNF örtülerini yara iyileşmesi için kapsamlı bir yaklaşım olarak ortaya koymaktadır.M.S. - Master of ScienceTÜBİTA
AoI-Driven IoT Fault Detection for Smart Grids
No full textEnsuring the reliability and efficiency of electric distribution grids necessitates real-time fault detection systems that prioritize data freshness and transmission efficiency. This paper presents the first Age of Information (AoI)-driven IoT fault detection system, powered by an AoI-optimized algorithm that dynamically adjusts transmission intervals to ensure timely and critical updates. By integrating ESP32 and STM32 micro-controllers with an MQTT-based communication framework, the system adapts to network conditions, mitigating congestion while improving data precision. As a pilot project, the system was deployed across five transformer stations on a live power grid, where it successfully detected 27 fault types with high accuracy. Experimental results show timely fault detection with minimal data use - 17 KB/year in fault mode and 55 MB/year in continuous mode - enabling long-term, battery-powered operation
Multifonksiyonel polimer kompozit nanoliflerin elektro-eğirme yöntemiyle işlenmesi ve karakterizasyonu
No full textIn the present work, the electrospinning parameters such as solution concentration,
solvent type, feed rate, applied voltage and tip-to-collector distance were optimized
to produce smooth poly(methyl methacrylate) (PMMA) fibers. Also, the effect of
halloysite nanotubes (HNTs), boron phosphate (BPO4) and poly(ethylene glycol)
(PEG) addition on the properties of the electrospun fibers was investigated. The
produced samples were characterized in terms of their morphologies, burning and
thermal behavior, dye adsorption capacities and wettability.
The preliminary results demonstrated that the optimal electrospinning parameters
were 20 wt.% polymer solution concentration, 1:3 acetone (ACE)/N,N
dimethylformamide (DMF) solvent ratio, 25 kV applied voltage, 0.4 ml/h feed rate
and 15 cm tip-to-collector distance.
Addition of HNT and BPO4 resulted in an increase in average fiber diameter, limiting
oxygen index (LOI) and water contact angle of the PMMA-based composite fibers
compared to neat PMMA fibers. Conversely, inclusion of PEG into PMMA matrix
led to decrease in fiber diameter.
The produced fibers were tested for the capability to adsorb methylene blue (MB)
and methyl orange (MO) from aqueous solutions. Water contact angle measurements
revealed that the addition of additives increased the hydrophobicity. The presence of
HNT and BPO4 in the samples led to increase in their methylene blue adsorption
capacities. PMMA/PEG-based composite containing 5 wt.% BPO4 was selected for
kinetic and isotherm studies. The adsorption kinetics were well described by the
pseudo-second-order model, and equilibrium data showed a better fit with the
Langmuir model. Additionally, the highest LOI value of 24.5% O2 was obtained for
PMMA/1 wt.% BPO4 composite.Bu çalışmada, düzgün poli(metil metakrilat) (PMMA) bazlı lifler üretmek için çözelti
konsantrasyonu, çözücü tipi, besleme hızı, uygulanan voltaj ve uçtan toplayıcıya
mesafe gibi elektro-eğirme parametrelerini optimize edilmiştir. Ayrıca, halloysit
nanotüp (HNT), bor fosfat (BPO4) ve poli(etilen glikol) (PEG) ilavesinin elektroeğirme
yöntemiyle üretilen liflerin özellikleri üzerine etkisi incelenmiştir. Üretilen
örnekler morfolojileri, yanma ve termal davranışları, boya adsorpsiyon kapasiteleri
ve ıslanabilirlikleri açısından karakterize edilmiştir.
Elde edilen ilk sonuçlar, elektro-eğirme işlemi için en uygun parametrelerin ağırlıkça
% 20'lik polimer çözeltisi konsantrasyonu, 1:3 aseton (ACE)/N,N-dimetilformamid
(DMF) çözücü oranı, 25 kV uygulanan voltaj, 0.4 ml/saat besleme hızı ve 15 cm uç-
toplayıcı mesafesi olduğunu göstermiştir.
HNT ve BPO4 ilavesi, saf PMMA liflerine kıyasla PMMA bazlı kompozit liflerin
ortalama lif çapı, sınırlı oksijen indeksi (LOI) ve su temas açısında artışa neden
olmuştur. Öte yandan, PEG’in PMMA matrisine dahil edilmesi lif çapında azalmaya
yol açmıştır.
Üretilen lifler, sulu çözeltilerden metilen mavisi (MB) ve metil turuncusu (MO)
boyar maddelerini adsorplama kapasiteleri açısından test edilmiştir. Su temas açısı
ölçümleri, katkı maddelerinin ilavesinin hidrofobisiteyi artırdığını ortaya koymuştur.
Örneklerde HNT ve BPO4 bulunması metilen mavisi adsorplama kapasitelerinde
artış sağlamıştır. Kinetik ve izoterm çalışmaları için ağırlıkça %5 BPO4 içeren
PMMA/PEG bazlı kompozit numunesi seçilmiştir. Adsorpsiyon kinetiği sözde ikinci
dereceden kinetik modeliyle iyi bir şekilde tanımlanırken; denge verileri ise
Langmuir izoterm modeli ile daha iyi uyum göstermiştir. Ek olarak, en yüksek %24.5
O2’lik LOI değeri PMMA bazlı ağırlıkça %1 BPO4 içeren kompozit örneğinde elde
edilmiştir.Ph.D. - Doctoral Progra
