Electrochemical Amperometric Biosensor Applications of Nanostructured Metal Oxides: A Review

Biological sensors have been extensively investigated during the last few decades. Among the diverse facets of biosensing research, nanostructured metal oxides (NMOs) offer a plethora of potential benefits. In this article, we provide a thorough review on the sensor applications of NMOs such as glucose, cholesterol, urea, and uric acid. A detailed analysis of the literature is presented with organized tables elaborating the fundamental characteristics of sensors including the sensitivity, limit of detection, detection range, and stability parameters such as duration, relative standard deviation, and retention. Further analysis was provided through an innovative way of displaying the sensitivity and linear range of sensors in figures. As the unique properties of NMOs offer potential applications to various research fields, we believe this review is both timely and provides a comprehensive analysis of the current state of NMO applications

A Novel Micro Piezoelectric Energy Harvesting System

(Doktora) -- İstanbul Teknik Üniversitesi, Fen Bilimleri Enstitüsü, 2007(PhD) -- İstanbul Technical University, Institute of Science and Technology, 2007Bu tezde yeni bir titreşim temelli mikro enerji harmanlayıcı sistemi önerilmiştir. Titreşimler ve ani hareketler, mekanik yapının sadece eğilmesine değil aynı zamanda gerilmesine yol açar, bu sayede sistem doğrusal olmayan bölgede çalışır. İnce piezoelektrik film tabakası mekanik stresi elektrik enerjisine çevirir. Mikrowatt mertebesinde güç seviyeleri mm3’lük aletlerle elde edilebilir, bu da güneş panellerinde elde edilen güç yoğunlukları kadar yüksektir. Algılayıcı kabiliyeti sayesinde bilgi depolayabilen, kum tanesi büyüklüğünde olan ve üretiminde kullanılan temel malzeme silikon olan bu aletler “zeki kum” olarak isimlendirilmiştir. Mekanik yapının modellenmesi ve tasarımı geliştirilmiş ve üretim sonuçları da ayrıca verilmiştir. Sistemin bilgi gönderebilmesi ve alabilmesi amacıyla iyi bilinen RFID teknolojisi tabanlı bir kablosuz haberleşme yöntemi önerilmiştir. Bu bağlamda, paket taşımacılığında sürekli ivme denetleme, sınır güvenliği için kendinden beslemeli algılayıcılar, çabuk bozulan yiyeceklerin taşımacılığında sıcaklık denetleme ve pilsiz kalp atışı algılayıcı gibi birçok uygulama önerilmiştir.In this thesis, a novel, vibration based micro energy harvester system is proposed. Vibrations or sudden movements cause the mechanical structure does not only bend but also stretch, thus working in non-linear regime. The piezoelectric thin film layer converts the mechanical stress into the electrical energy. Microwatts of power can be achieved with a mm3 device which yields a high power density levels on the order of the solar panels. This device is named “smart sand”, because it has also sensor capabilities that can store information, its size is almost a sand grain and the main material used for the fabrication is silicon. The modeling and design of the mechanical structure has been developed and fabrication results have also been given in the thesis. In order for the system to send and receive the information, a wireless communication scheme is proposed which is based on the well-known RFID technology. In this concept, several applications are proposed such as continuous acceleration monitoring in package delivery, self-powered sensors for homeland security, temperature monitoring of the perishable food item delivery and a batteryless heart rate sensor.DoktoraPh

Unraveling the Energy Use Network of Construction Sector in Turkey Using Structural Path Analysis

Input-output analysis provides a useful framework for examining the direct and the indirect changes in the energy use. The purpose of this study is to gain a better understanding of the energy use network in Turkish construction (CON) sector. To do this, a particular type of network analysis, Structural Path Analysis is conducted. Sectoral energy use data provided by World Input-Output Database is used for the elaboration of energy paths. Mediating sectors underlying backward energy linkages are identified. Results show that energy use of CON increased both in absolute terms and that of rank among other industries. The magnitude and complexity of the coke and refined petroleum path decreased. Due to the expansion in natural gas powered energy production, relative importance and complexity of the electric, gas and water supply path increased. Energy use paths are discussed with reference to current account deficit and growth issues in Turkey. Keywords: Energy use, input-output modelling, structural path analysis, construction sector, Turkey JEL Classifications: C67, L74, Q4

Fuzzy-pso Control Of Linear And Nonlinear Systems

Tez (Yüksek Lisans) -- İstanbul Teknik Üniversitesi, Fen Bilimleri Enstitüsü, 2014Thesis (M.Sc.) -- İstanbul Technical University, Institute of Science and Technology, 2014Bu tezin amacı, yeni optimizasyon yöntemi olan parçacık sürü optimizasyon algoritmasını MATLAB’e uygulayarak bulanık PID kontrolörü katsayıları ve Takagi-Sugeno kural tabanındaki keskin değerleri cevrimdışı optimize ederek doğrusal ve doğrusal olmayan sistemlerin belirli çalışma koşulları altında kontrolünü sağlamaktır. Parçacık sürü optimizasyonunun diğer optimizasyon yöntemlerinden, örnek olarak verilmesi gerekirse genetik algoritmadan, en önemli avantajı optimizasyon sırasında az sayıda iterasyon içermesi, kolay anlaşılabilir olması ve bize kompleks olmayan az sayıda yazılmış bilgisayar kodları ile kolay ve ucuz bir şekilde uğraşmamızı sağlamasıdır. Genetik algoritma ile olan benzerlikleri ise her ikiside populasyon tabanlı olup, tek set değerden diğer set değerlere geçerken deterministik ve olası kuralları kullanmaları sayılabilir. Son yapılan çalışmalara istinaden parçacık sürü optimizasyon yöntemi en az genetik algoritma kadar büyük oranda doğrusal olmayan yapıların çözülmesinde, yakınsama oranı ve yakınsama hassasiyeti bazında aynı sonuçları vermektedir. Ayrıca basit kodlar içermesinden dolayı hem bilgisayar hafızasından hem de zamandan tasarruf ettirip sonuclara en hızlı ve verimli şekilde ulaşmamıza yardımcı olmaktadır. Parçacık sürü optimizasyon yöntemi doğrusal olmayan ve zamanla değişen karakteristiğe sahip olan ikili tank sisteminde belirli çalışma aralıkları içerisinde bulanık PID kontrolör tasarımında kolayca ve başarılı bir şekilde uygulanabilmiştir. Yukarıda bahsedildiği gibi ikili tank sisteminin doğrusal olmayan ve zamanla değişen yapısından dolayı, kontrolör tasarımında tek set parametrelerin bulunması ve kontrol sırasında her bölge için aynı parametrelerin kullanılması neredeyse imkansızdır. Bu yüzden daha önceden belirlenmiş çalışma aralıkları içerisinde, Takagi-Sugeno kural tabanındaki parçacık sürü optimizasyon yöntemi ile optimize edilmiş katsayılar her bölge için sabit tutularak, değişik bölgeler için değişik optimal kontol parametreleri bulunup kontrol sırasında çevrimiçi olarak PID katsayılar hesaplanmıştır. Bulanık PID kontrolör parametreleri aynı zamanda ikili tank sisteminin ikinci tankındaki sıvı seviyesini giriş set değeri alarak farklı çalışma aralıklarında doğrusal regresyon yöntemi ile bulunan değişik kontrolör parametre fonksiyonları ile esnek bir yapıya dönüştürülüp farklı giriş değerleri, sistem gürültülerini hatta sistem hatalarını kompanze edecek duruma getirilimiştir. Böylelikle belirlenen çalışma bölgelerinde istenilen kontrol şartlarını sağlayan, değişik senaryolara sahip sistem hataları ve sistem gürültülerini bastıran adaptif yapıya sahip doğrusal olmayan bir sistemin geliştirilmiş parçacık sürü optimizasyonu yöntemi ve bulanık PID kontrolörü ile kontrolü sağlanmıştır.The goal of the thesis is to introduce a new global optimization method called particle swarm optimization that is implemented via MATLAB to use to find the optimal parameters for PID coefficients and Takagi-Sugeno rule base’s crisp values in order to control linear and nonlinear systems within specified operating conditions. The most important advantages of particle swarm optimization algorithm is that it requires less number of iterations and it enables us to deal with a few lines of computer codes in a cheapest manner rather than other optimization methods such as genetic algorithm. It requires only primitive mathematical operators in terms of both necessity of more available memory and speed. Particle swarm optimization method has been successfully applied to the design of coupled tanks system control with meaningful time domain criteria. Since the coupled tank system to be controlled is nonlinear and time varying charecteristic, it is almost not possible to find one set of parameters that satisfy for all operating conditions. Therefore some predetermined operating points have been chosen and find out the optimal control parameters’ values for the operating points while keeping Takagi-Sugeno crisps values constant for all operating points within the different ranges. Different functions are calculated for each controller parameters within different operating points based on the referenced height of tank two as an input value to the coupled tank system by using the predetermined points and least curve-fitting algorithm. It has been observed that these functions, which derive fuzzy controller parameters, have achieved very satisfactorly systems responses.The water levels between different ranges are chosen respectively as a three typical operating regions of second tank and input space is divided into three fuzzy subspaces based on operating regions. Fuzzy PID parameters have been calculated online by proposed method despite of the fact that Takagi Sugeno crisp values have been calculated offline and stored before calculating PID parameters for the three operating regions. We can generalize that Takagi-Sugeno crisp values, which are structural parameters, are determined offline design while the tuning parameters are calculated during online adjustment of fuzzy PID controller to enhance the process performance, as well as to accommodate the adaptive capability to system uncertainty and process disturbances. The proposed architecture is also tested in case of process disturbance and systems faults. Simulation results showed that the couple tank system was successfully controlled with acceptable performance criterions in both cases.Yüksek LisansM.Sc

Science of Batteries

Lots of myths and legends are currently surrounding the world of batteries today. This poster gives some insight into this world of batteries in 2019. Our research and findings is both for scientifically engaged individuals working in the battery industry, either in creation or usage, and the general populous alike

Regional employment generation potential of the Turkish labor market: an inter-sectoral perspective

Contractionary effects of the current global crisis are not homogenous among sectors. Moreover, sectoral employment multipliers and high regional unemployment differentials unequally transfer these effects into labor market. The purpose of this study is to explore the inter-sectoral sensitivities of regional labor markets in Turkey to changes in the final demand. To do this, we decompose the labor demand by sectors and by regions using input-output methodology. Own employment generation effects and regional employment multipliers of each sector are calculated. Overall findings constitute an employment generation map of Turkey. One of the major findings is the strength of the mutual relationship between agriculture and manufacturing sectors. The biggest spillover effect is created by manufacturing upon mostly agriculture, trade and transportation. Agriculture, social services and trade are the most sensitive sectors to changes in the final demand. At regional level; trade, social services and manufacturing are the most influential sectors on Istanbul. Besides, agriculture, social services and construction sectors have the highest employment generation potentials in South Eastern Anatolia. First published online: 17 Apr 201

A brand choice model based on house-hold panel data: An empirical model of CSD choice in Turkey

Tüketici panelleri günümüzde gerek pazarlama yöneticileri gerekse marka tercih modelleri üzerinde çalışan akademisyenler tarafından yaygın olarak başvurulan bir veri kaynağı haline gelmiştir. Gelişmiş ülkelerde genellikle tarayıcı teknolojilerine dayalı olarak toplanan tüketim paneli verisi gelişmekte olan ülkelerde günlük tutma yöntemiyle elde edilmektedir. Bu yöntemle toplanan hane paneli verilerinin kapsam ve güvenilirliğinin tarayıcı teknolojisiyle elde edilen verilere göre daha sınırlı olduğu kabul edilmektedir. Bu çalışmanın amacı, alışveriş günlüğüne dayalı tüketici paneli verisiyle Türkiye’de, hızlı tüketim malları sektöründe, başarılı bir marka tercih modeli kurabilmenin mümkün olup olmadığını araştırmaktır. Bu amaçla, öncelikle, günlük tutma yöntemine dayalı panellerde doğrudan ulaşmanın mümkün olmadığı rakip markalara ait fiyat bilgilerini üretmeye yönelik dört aşamalı bir yöntem önerilmiştir. Daha sonra, Türkiye’de 2004 yılında 1632 hane tarafından yapılmış 26031 kolalı içecek alışverişinden yararlanılarak çeşitli çoklu probit ve lojit modelleri kurulmuş; modellerden elde edilen bulgular rassal olarak belirlenen 408 hanelik test örneklemine ait 6686 alışveriş gözlemi üzerinde sınanmıştır. Sonuçlar göreli fiyatlar, hane büyüklüğü, toplam harcama, bir önceki tercih ve sosyo-ekonomik statü açıklayıcı değişkenlerinin yüksek güven düzeylerinde anlamlı olduğunu ve kurulan modellerin gerek test gerekse model örneklemlerindeki hanelerin marka tercihlerini başarıyla tahmin ettiğini göstermektedir. Yapılan marjinal etki analizlerine seçilen modellerin verdiği tepkiler de teorik beklentilerle hassas bir uyum içindedir. Bu çalışma, Türkiye’de hane paneli verisi ile tüketicilerin bir sektördeki marka tercihlerini modellemeyi hedefleyen öncü çalışmalardan biri olması bakımından önem taşımaktadır. Anahtar Kelimeler: Tüketim paneli, marka tercih modeli, çoklu probit, Hızlı Tüketim Malları, alışveriş günlüğü.One of the major sources of consumer level brand consumption data in Fast Moving Consumer Goods (FMCG) sector is the household consumer panels maintained by individual organizations. Consumer panels are capable of keeping histories of purchases for a sample of households. Household panel data is collected via barcode scanner technologies in the developed countries. Data collected by the optical scanning of Universal Product Code permits researchers study the effects of marketing variables on customer choice among product alternatives since the mid-1980s and many dozens of papers are published on brand and retailer choice issues since then. Employing scanner technology, panel organizations does not require its members to record all the items they purchase in a shopping trip, as their panel ID cards are scanned during the payment process at checkout. Building cooperation with the retailer companies, scanner panels are able to provide price and promotion data for all the products (in a given product category) without the necessity of being purchased. On the other hand, due to the high levels of technology costs, the household level panel information in developing markets is primarily gathered using the diary mode. It is believed that, in this mode of data collection, both the reliability and the scope of information collected from the panellists are still scarce compared to their scanner type counterparts in more developed markets. One of the important problems of diary mode data is the lack of complete price information. In diary mode panel organizations, households only record the prices of the products they purchase. As it is impossible for a shopper to list the prices of all the products in the product categories (of which the shopping basket includes an item), diary mode household panels are not capable of conducting complete price data in a given product category. As the brand choice models literature using household panel data mostly stands upon the unit prices of the products purchased and their alternatives displayed on shelves, there is a gap of modelling research in the developing markets in which consumer panel measurements are made based on diary mode. The purpose of this study is to investigate whether it is possible to establish an efficient brand choice model based on diary mode household panel data from the Turkish carbonated soft drinks market.  In order to accomplish this goal, firstly, a four staged method of price data generating is suggested. Suggested method basically generates artificial unit prices for the products which are present at the retailer during the shopping trip but not purchased. Secondly, employing this price data, different multinomial probit and logit models of brand choice are built based on 26031 purchase occasions of a model sample of 1632 households. Using relevant goodness of fit and specification tests (mostly depending on the number of choices that were made correctly), the performances of these six models are tested on the 6686 purchases of a randomly selected test sample of 408 households. The results show high significance for the explanatory variables of brand loyalty (previous brand purchased), relative prices and household specific features such as total/per capita FMCG spending, household size and socio-economical status. While the coefficients have expected signs, the models predict the share of purchases remarkably well in both the model and the test samples. All of the models are capable of predicting more than three thirds of the brand choices correctly. However, Hausman tests reveal that the Independence of Irrelevant Alternatives criteria does not hold for the multinomial logit models. Therefore, theoretically, it is not possible to use the multinomial logit method in modelling the Turkish carbonated soft drinks market, although it was useful in variable selection process.  Hopefully, the goodness of fit measures and specification tests show that, there is no theoretical problem for the multinomial probit models of brand choice built in this study. Moreover, the reactions of the probit models to the marginal effect analyses are consistent with the theoretical expectations and the models are capable of predicting the monthly shares of purchases with the error range of 3% successfully. Employing diary based consumer panel data, this study is one of the pioneering attempts to integrate the consumption level data and consumer features towards developing a brand choice model in Turkey. Keywords: Consumer panel, brand choice model, multinomial probit, Fast Moving Consumer Goods (FMCG), diary mode panel data

A Real-Time Wireless Sweat Rate Measurement System for Physical Activity Monitoring

There has been significant research on the physiology of sweat in the past decade, with one of the main interests being the development of a real-time hydration monitor that utilizes sweat. The contents of sweat have been known for decades; sweat provides significant information on the physiological condition of the human body. However, it is important to know the sweat rate as well, as sweat rate alters the concentration of the sweat constituents, and ultimately affects the accuracy of hydration detection. Towards this goal, a calorimetric based flow-rate detection system was built and tested to determine sweat rate in real time. The proposed sweat rate monitoring system has been validated through both controlled lab experiments (syringe pump) and human trials. An Internet of Things (IoT) platform was embedded, with the sensor using a Simblee board and Raspberry Pi. The overall prototype is capable of sending sweat rate information in real time to either a smartphone or directly to the cloud. Based on a proven theoretical concept, our overall system implementation features a pioneer device that can truly measure the rate of sweat in real time, which was tested and validated on human subjects. Our realization of the real-time sweat rate watch is capable of detecting sweat rates as low as 0.15 µL/min/cm2, with an average error in accuracy of 18% compared to manual sweat rate readings

A Framework for Biomechanical Analysis of Jump Landings for Injury Risk Assessment

Competitive sports require rapid and intense movements, such as jump landings, making athletes susceptible to injuries due to altered neuromuscular control and joint mechanics. Biomechanical features during landings are associated with injury risk, emphasizing proper movement and postural stability. Computer vision techniques offer a time-efficient, noninvasive, and unbiased method to assess jump-landings and identify injury risks. This study proposes a video analysis framework to evaluate jump landing biomechanics in athletes todetermineirregularmovementsandincorrectpostures.It providesadviceandrecommendationstocoachesforinjury predictionandtrainingimprovements.Theproposedframework istestedusingcountermovementjumpvideosof17NCAA DivisionIfemalebasketballathletes.Theresultsindicateda lowMeanAbsoluteError(0.97),highcorrelation(0.89),high averageaccuracy(98.31%)andF1score(0.98),signifyingthe framework’sreliabilityinidentifyinginjuryrisk

A novel MEMS based batteryless active RFID system

Bu makalede yeni bir titreşim temelli mikro enerji harmanlayıcı sistemi önerilmiştir. Titreşimler ve ani hareketlerin, mekanik yapının sadece eğilmesine değil aynı zamanda gerilmesine yol açması prensibine dayanarak, sistemin doğrusal olmayan bölgede çalışması sağlanmıştır. Tasarlanan ve modellemesi yapılan mekanik yapının üzeri ince bir piezoelektrik film tabakası ile kaplanmış ve bu tabaka üzerinde oluşan mekanik stres elektrik enerjisine çevrilerek devreleri beslemek için kullanılmıştır. Doğrusal olmayan bölgede çalışmanın, mikrowatt mertebesindeki güç seviyelerini mm3’lük aletlerle elde edebileceği göz önüne alındığında, güneş panellerinde elde edilen güç yoğunlukları kadar yüksek enerjilerin elde edilebileceği görülmüştür. Algılayıcı kabiliyeti sayesinde bilgi depolayabilen, kum tanesi büyüklüğünde olan ve üretiminde kullanılan temel malzeme silikon olan bu aletler “zeki kum” olarak isimlendirilmiştir. Mekanik yapının modellenmesi ve tasarımı geliştirilmiş ve üretim sonuçları da ayrıca verilmiştir. Sistemin bilgi gönderebilmesi ve alabilmesi amacıyla iyi bilinen RFID teknolojisi tabanlı bir kablosuz haberleşme yöntemi önerilmiştir. Bu bağlamda, paket taşımacılığında sürekli ivme denetleme, sınır güvenliği için kendinden beslemeli algılayıcılar, çabuk bozulan yiyeceklerin taşımacılığında sıcaklık denetleme ve pilsiz kalp atışı algılayıcı gibi birçok uygulama önerilmiştir. RFID devrelerinin tasarımı yapılmış ve benzetim sonuçları elde edilmiştir. Oku-yaz bellek olarak manyetik belleklerden yararlanılmıştır. Bu sayede, pil kullanılmadan aktif bir şekilde veri yazabilen bir sistem yaratılmıştır. “Zeki RFID” olarak isimlendirilen bu sistemde ayrıca bilginin iletimi için de yeni bir modülasyon yöntemi önerilmiştir.  Anahtar Kelimeler: Enerji harmanlayıcı, RFID, mikroelektronik, MEMS.In this paper, a novel, vibration based micro energy harvester system has been proposed. The modeling, design and fabrication of the devices have been carried out. There are several propositions in this work. The biggest claim is to achieve high power density levels with a mm3 device by using a novel vibration based mechanical structure. The operating regime is nonlinear unlike its conventional counterparts, which yields to generate more electrical energy. The proposed packaging method of the device is very simple and easy to realize. Furthermore, a wireless communication scheme based on the well-known RFID (Radio Frequency Identification) technology has also been proposed. The mechanical structure of the device is based on a clamped-clamped beam where four tethers share a thick proof mass. The proof mass is used in order to bring the first eigenfrequency of the system below 50Hz which enlarges the operating frequency range.  The surface of the proof mass also acts as a platform for the sensor circuits. Vibrations or sudden movements cause the mechanical structure do not only bend but also stretch, thus working in non-linear regime. The piezoelectric thin film layer on the silicon tethers converts the mechanical stress into the electrical energy. Microwatts of power can be achieved with a mm3 device which yields a high power density levels on the order of the solar panels. This device is named 'smart sand', because it has sensor capabilities that can store information, its size is almost a sand grain and the main material used for the fabrication is silicon. The modeling and design of the mechanical structure has been developed by using COMSOL" (a finite element analysis (FEA) tool) and SIMULINK" (an extension tool of MATLAB). Firstly, the stress levels have been calculated and the transient response of the structure has been investigated. Then, the theoretical analysis has been combined with these two tools and expected power density levels have been found. The fabrication of the "smart sand" has also been developed in this work. Bulk micromachining techniques have been used in order to form the proof mass. The piezoelectric thin film layer has been deposited onto the tethers by sol-gel method. Electrodes of the piezoelectric layer have been fabricated by the lift-off process. The packaging has been embedded into the fabrication process which reduced the handling issues during the process. An elastomer (poly dimethyl siloxane, PDMS) which is very easy to pattern, handle and cheap has been used for the packaging which has not been tried before. The "smart sand" serves as a typical accelerometer which senses the continuous vibrations or sudden accelerations. In order to further develop the sensor capabilities of the system, a new approach has been proposed which is called the "smart RFID" platform where the device has been combined with the RFID concept. In this context, an RFID transponder has been designed. The circuitry has the capabilities of sending and receiving 64 bits of data. The 64-bit memory has been constructed with the magnetic random access memory (MRAM) cells. Few bits have been reserved for the acceleration or temperature data. When a sudden or continuous acceleration happen, the "smart sand" generates voltage and this voltage is used to write the memory bits without the need of a battery. Therefore, the "smart RFID" platform behaves like a batteryless active RFID transponder. In order to determine whether the adequate voltage level is reached or not, a mechanical relay has been proposed and its design has been investigated. Other bits are used for standard identification and they are written or read via an external reader. The frequency of operation has been chosen 2.45GHz. Several applications have been proposed that is possible to use the "smart RFID" platform; such as continuous acceleration monitoring in package delivery, self-powered sensors for homeland security, temperature monitoring of the perishable food item delivery and a batteryless heart rate sensor. Their feasibilities have been investigated and discussed.The applications can be further enhanced and new application alternatives can be developed. The proposed RFID platform has been designed and simulated. All sub-blocks have been designed and the results have been given. In addition to the standard circuit designs, a new modulation technique has been proposed and simulated. This technique eases the data and clock recovery circuits. Keywords: Energy Harvester, RFID, Microelectronics, MEMS.