Browsing by Subject "Control"

Now showing 1 - 13 of 13

Restricted
1990-2000 yılları arasında Türkiye’de kuduzla mücadele
(Bilkent University, 2024) Yağan, Elif Ceren; Taşçı, Helin; Altın, Mehmet Emir
Bu makale, Ankara Üniversitesi enfeksiyon anabilim başkanı olan Prof. Dr. Serhat Birengel ile görüşülerek yapılan 1990-2000 yılları arasında Türkiye'de kuduzla mücadele, yaşanan zorluklar ve çıkarılan derslere ışık tutmayı amaçmalaktadır. Bu dönemde aşılama kampanyaları düzenlenmiş, hayvan popülasyonları kontrol altına alınmış ve toplumun bilinç düzeyi artırılmıştır. Ancak, kırsal bölgelerdeki erişim zorlukları ve yetersiz kaynaklar gibi zorluklarla karşılaşılmıştır. Bu zorluklara rağmen, kuduzla mücadelede elde edilen deneyimler, daha etkili stratejilerin belirlenmesi ve uygulanması için önemli bir temel oluşturmuştur. Gelecekte, kuduzla mücadelede karşılaşılan zorlukların üstesinden gelmek için daha fazla çaba harcanması ve kaynakların daha etkin bir şekilde kullanılması gerekmektedir. Bu şekilde, kuduzun kontrol altına alınması ve toplumun genel sağlığının korunması sağlanabilir.
Open Access
A miniature, foldable, collision resilient quadcopter
(2023-06) Bakır, Alihan
In the fields of surveillance, mapping and security, the use of unmanned aerial vehicles (UAVs), is becoming inevitable day by day, especially with their au-tonomous movement capabilities. The main reason for the increasing use of un- manned aerial vehicles is their ability to map and survey unknown and dangerous places such as caves without risking human life. At the same time, the ability to conduct aerial surveillance in full autonomy for public safety and health is also an important factor. Today, UAVs are used for many purposes, such as cave mapping and surveying, detection and intervention of forest fires, and inspection of outdoor and crowded areas for security purposes, often accompanied by an operator. Quadcopters are also used for missions that do not require long duration flight, as they are able to both hold position and ensure a highly stable flight. In addition to their many advantages, these UAVs are very sensitive to even the slightest impact, so their fully autonomous flight is still limited to controlled areas. Various studies are being conducted to increase the crash resistance of the quadcopters. Among these researches, there are different ideas such as protective shells and bumpers that surround the UAV and absorb the impact in case of collisions. The spherical cases that surround the UAV are usually in a mesh structure to be lightweight and not obstruct the airflow. Bumpers designed to protect the most sensitive parts of the UAV, such as the motors and propellers, are insufficient to protect the body. For these reasons, making different parts of the UAV from more flexible materials will eliminate the vulnerability of the UAV and increase its resistance to collisions. In this thesis, in order to increase the impact resistance of quadcopters and to ensure that they do not break, robots with some flexible and some rigid parts were tested and the results of these tests were evaluated in detail. During these tests, the effects of the compliance of the robot’s arms and the compliance of the bumpers protecting the propellers upon the impact were analyzed. In order to make this comparison, flexible and rigid robot bodies with dimensions as close as possible to each other, as well as rigid and flexible bumpers of similar size and structure were designed. The flexible bumper and body were produced by cutting PET sheets via a laser cutter and folding them in an origami-inspired pattern. This production method adds flexibility thanks to the thinness of the PET sheets and structural rigidity thanks to the origami-inspired folding technique. To in- crease the flexibility of the robot in the event of a collision and the stability of the motors, inserts made of TPU are inserted into the body. In addition to impact resilience, this thesis also discusses a soft sensor that can be attached to collision-resiliant drones. This sensor, made of conductive TPU, allows the robot to sense its surroundings by giving it a sense of touch. Thanks to the flexible sensor, robots can detect when a collision occurs and react accordingly. This sensor works entirely based on the flexibility of the UAV’s bumpers and senses the bending of these bumpers. Therefore, such a sensor cannot be used on rigid hulls and bumpers as they do not bend.
Open Access
Decentralized blocking zeros in the control of large scale systems
(1992) Ünyelioğlu, Konur Alp
lu lliis lliesi.s, a luuiiber ot syiithe.sis problems i'or linear. ninc-invariauL, iiiiite-cliuieiiSioiial sysiems are adclres.se(l. It i.s sliown that tlie lu'w concejU of (l·.': m inili zed blocking zeros \s as fmidaineiital to controller .synthesis problems for large scale systems as the concept of decentralized fixed modes. The main problems considered are (i) decentralized stabilization problem, (ii) decentralized strong stabilization problem, and (iii) decentralized concurrent stabilization problem. 7'he dtcenIralized siabUizaiion problem is a fairly well-understood controller synthesis problem for which many synthesis methods exist. Here, we give a new .synthesis procedure via a proper stable fractional approach and focus our attention on the generic solvability and characitnzalion of all solutions. The decenlralized strong .stabilization problem is the problem of stabilizing a .systeni using stable local controllers. In this problem, the .set of decentralized blocking zeros play an essential role and it turns out that the problem has a solution in case tlie poles and the real nonnegative decentralized blocking zeros have parity interlacing property. In the more general problem of decentralized stabilization problem with minimum number of unstable controller poles, it is shown tliat this minimum number is determined by the nuiid.H-»r of odd distributions of plant poles among the real nonnegative decentralized blocking zeros. The decentralized concurrent stabilization problem is a special type of simultaneous stabilization problem using a decentralized controller. Tliis problem is of interest, since many large scale synthesis problems turn out to be its special cases. A complete solution to decentralized concurrent stabilization problem is obtained, where again the decentralized blocking zeros play a central role. Three problems that have receiviHİ wide atteiuion in tlie literature of large scale .systems: stabilization o f composite systems using locally :>tabilizing subsystem controllers, stabilization uf composite system.^ na the slabilization o f mam diagonal transfer matrices, and rcliablt decentralized siabilizaiion problem are solved by a specialization of oiir main result on decentralized concurrent stabilization problem.
Open Access
A delayed consensus algorithm in networks of anticipatory agents
(IEEE, 2016) Atay, Fatihcan M.; Irofti, D.
We introduce and analyze a delayed consensus algorithm as a model for interacting agents using anticipation of their neighbors' states to improve convergence to consensus. We derive a necessary and sufficient condition for the system to reach consensus. Furthermore, we explicitly calculate the dominant characteristic root of the consensus problem as a measure of the speed of convergence. The results show that the anticipatory algorithm can improve the speed of consensus, especially in networks with poor connectivity. Hence, anticipation can improve performance in networks if the delay parameter is chosen judiciously, otherwise the system might diverge as agents try to anticipate too aggressively into the future.
Open Access
Development of a supervisory controller for residential energy management problems
(AACC, 2012-06) Akgün, Emre; Çakmakçı, Melih
In recent years, the infrastructure that supplies energy to residential areas has started to evolve into a multi-source system, just like in automotive industry in which hybrid electric vehicles (HEVs) have been replacing conventional gasoline vehicles. Multi energy source systems considered as a potential solution for carbon emission problems despite their challenges in their operation due to increased complexity. In this paper, a control design approach successfully applied in the automotive industry is used to solve a residential energy management problem. First, a dynamic programming method is applied to obtain optimal control actions for the representative demand profiles and then by using these results, a causal supervisory controller is developed. It is found that the developed baseline controller performs 1-2% better daily in its initial form in terms of operational costs, compared to available heuristic strategies. © 2012 AACC American Automatic Control Council).
Open Access
Effects of compliance on path-tracking performance of a miniature robot
(IEEE - Institute of Electrical and Electronics Engineers, 2023-05-15) Uğur, Mustafa; Arslan, Burak; Özzeybek, Alperen; Özcan, Onur
Path-tracking is often challenging in miniature robots because their feet or wheels tend to slip due to the low robot weight. In this work, we investigate the effect of c-leg compliance on path-tracking performance and the obstacle-climbing capabilities of our foldable and miniature robot with soft, c-shaped legs. With its 82 mm x 60 mm x 29 mm size and 29.25 grams weight, a single module of our robot is one of the smallest untethered miniature robots. Our results show that utilizing soft c-shaped legs provides smooth path-tracking performance, similar to a wheeled differential drive robot. However, modules with rigid c-shaped legs are affected significantly by the impact and slip between the leg and the ground, and they perform rather unpredictably. Additionally, modules with wheels cannot climb obstacles 1 mm or larger. We show that using soft legs enhances the obstacle climbing skills of modules by climbing a 9 mm obstacle, while the module with rigid legs can only climb a 7 mm obstacle. These path-tracking abilities and obstacle-climbing capacity support our vision to build a reconfigurable robot using these modules.
Open Access
Identification of some nonlinear systems by using least-squares support vector machines
(2010) Yavuzer, Mahmut
The well-known Wiener and Hammerstein type nonlinear systems and their various combinations are frequently used both in the modeling and the control of various electrical, physical, biological, chemical, etc... systems. In this thesis we will concentrate on the parametric identification and control of these type of systems. In literature, various identification methods are proposed for the identification of Hammerstein and Wiener type of systems. Recently, Least Squares-Support Vector Machines (LS-SVM) are also applied in the identification of Hammerstein type systems. In the majority of these works, the nonlinear part of Hammerstein system is assumed to be algebraic, i.e. memoryless. In this thesis, by using LS-SVM we propose a method to identify Hammerstein systems where the nonlinear part has a finite memory. For the identification of Wiener type systems, although various methods are also available in the literature, one approach which is proposed in some works would be to use a method for the identification of Hammerstein type systems by changing the roles of input and output. Through some simulations it was observed that this approach may yield poor estimation results. Instead, by using LS-SVM we proposed a novel methodology for the identification of Wiener type systems. We also proposed various modifications of this methodology and utilized it for some control problems associated with Wiener type systems. We also proposed a novel methodology for identification of NARX (Nonlinear Auto-Regressive with eXogenous inputs) systems. We utilize LS-SVM in our methodology and we presented some results which indicate that our methodology may yield better results as compared to the Neural Network approximators and the usual Support Vector Regression (SVR) formulations. We also extended our methodology to the identification of Wiener-Hammerstein type systems. In many applications the orders of the filter, which represents the linear part of the Wiener and Hammerstein systems, are assumed to be known. Based on LS-SVR, we proposed a methodology to estimate true orders
Open Access
Kurumsal yönetim bakımından şirketler topluluğunda piramit yapılanma ve buna bağlanan hukuki sonuçlar
(2023-06) Manavgat, Zeynep Berin
Şirketler topluluğunun özel bir görünüm biçimi olan piramit yapılanma, hakim teşebbüsün doğrudan ve dolaylı hakimiyet ile yarattığı bir hakimiyet zinciri olarak tanımlanabilir. Söz konusu yapılanma sayesinde hakim teşebbüs, özellikle alt basamaklarda yer alan şirketlere düşük sermaye miktarı koymakla birlikte, sermaye payından bağımsız bir yönetim gücü elde edebilmektedir. Böylece hakim teşebbüs bakımından malvarlıksal haklarla yönetim haklarının birbirinden ayrıldığı bir yapı ortaya çıkmaktadır. Bu durum bağlı şirket pay sahipleri, alacaklıları ve genel anlamda kurumsal yönetim anlayışı açısından olumsuz sonuçlar doğurabilmektedir. Piramit yapılanma bir topluluk yapılanması olduğu için topluluk hükümlerine tabi iken, özellikle dolaylı hakimiyetle ortaya çıkan kurumsal yönetim sorunları bakımından özel olarak incelenmelidir. Bu çalışmada, topluluk yapılanmasının özel bir hali olan piramit yapılanma kavramı açıklandıktan sonra, bu kavramın benzer kavramlarla karşılaştırılması ve piramit yapılanmaların olumlu ve olumsuz yönleri incelenmiştir. Çalışmanın ilerleyen kısımlarında, piramit içinde yer alan halka açık şirketlerin özellik arz eden noktaları üzerinde durulmuş; kurumsal yönetim bakımından piramit yapılanmaların sebep olduğu sorunlara yine kurumsal yönetim bakış açısıyla çözüm önerileri getirilmiştir.
Open Access
Learning based cross-coupled control for multi-axis high precision positioning systems
(ASME, 2012-10) Geçer-Ulu, Nurcan; Ulu, Erva; Çakmakçı, Melih
In this paper, a controller featuring cross-coupled control and iterative learning control schemes is designed and implemented on a modular two-axis positioning system in order to improve both contour and tracking accuracy. Instead of using the standard contour estimation technique proposed with the variable gain cross-coupled control, a computationally efficient contour estimation technique is incorporated with the presented control design. Moreover, implemented contour estimation technique makes the presented control scheme more suitable for arbitrary nonlinear contours. Effectiveness of the control design is verified with simulations and experiments on a two-axis positioning system. Also, simulations demonstrating the performance of the control method on a three-axis positioning system are provided. The resulting controller is shown to achieve nanometer level contouring and tracking performance. Simulation results also show its applicability to three-axis nano-positioning systems. Copyright © 2012 by ASME.
Open Access
Optimal pattern of technology adoptions under embodiment: a multi-stage optimal control approach
(John Wiley & Sons Ltd., 2011) Saglam, C.
By deriving the necessary conditions for a multi-stage optimal control problem where the endogenous switching instants appear as an argument of the state equation, we analyze the optimal pattern of technology adoptions under embodiment with a finite planning horizon. We show that the optimal pattern of technology adoptions depends crucially on how the growth rate advantage compares to the adjustment and the obsolescence costs inherent to embodiment. We obtain non-stationary lifetimes for the adopted technologies due to finite planning horizon. We analyze numerically the effects of planning horizon, speed of adjustment to the new technology, growth rate of technology and the impatience rate on the optimal pattern. Copyright © 2010 John Wiley & Sons, Ltd.
Open Access
Robust adaptive stabilization of a class of systems under structured nonlinear perturbations with application to interconnected systems
(Taylor & Francis, 1996) Wei, R.; Sezer, M. Erol; Ocalı, Ogan
This paper presents a stabilization scheme for a dass of multi-input/multioutput systems with nonlinear additive perturbations using high-gain adaptive controllers The nominal system is assumed to satisfy some mild conditions required by standard adaptive control schemes, and the perturbations certian structural conditions. The controller is a dynamic output feedback containing a gain parameter, which is adjusted with a simple adaptation rule. The result is also applied to decentralized stabilization of a class of interconnected systems, where the interconnections are treated as perturbations to nominally decoupled subsystems.
Open Access
Şirketler topluluğunda devralmalar bağlamında hakimiyet ve kontrol kavramı
(2022-09) Korkmaz, Gülce
Bu tezde, şirketler topluluğunda (topluluk içinde gerçekleşen veya topluluk süjelerinin gerçekleştirdiği) devralma işlemleri, hakimiyet – kontrol kavramı ekseninde incelenmiştir. İlk bölümde, şirketler topluluğu kavramı ile topluluğun unsurları incelenmiş, şirketler topluluğu benzer kavramlarla karşılaştırılmıştır. İkinci bölümde şirketler topluluğunda devralmaların hakimiyet ve kontrol kavramına dayalı olarak özellik gösterdiği hususlar olan kolaylaştırılmış birleşme, rekabet hukukunda grup içi işlemler ve ciro hesabı ile pay alım teklifi zorunluluğunun doğmadığı durumlar ile zorunlu pay alım teklifinden muafiyet incelenmiştir. Üçüncü bölümde, şirketler hukukunda, rekabet hukukunda, sermaye piyasası hukukunda, banka hukukunda ve finansal raporlama standartlarında kontrol kavramının farklı görünümlerine değinilmiştir.
Open Access
State-dependent control of a single stage hybrid system with poisson arrivals
(2011) Gokbayrak, K.
We consider a single-stage hybrid manufacturing system where jobs arrive according to a Poisson process. These jobs undergo a deterministic process which is controllable. We define a stochastic hybrid optimal control problem and decompose it hierarchically to a lower-level and a higher-level problem. The lower-level problem is a deterministic optimal control problem solved by means of calculus of variations. We concentrate on the stochastic discrete-event control problem at the higher level, where the objective is to determine the service times of jobs. Employing a cost structure composed of process costs that are decreasing and strictly convex in service times, and system-time costs that are linear in system times, we show that receding horizon controllers are state-dependent controllers, where state is defined as the system size. In order to improve upon receding horizon controllers, we search for better state-dependent control policies and present two methods to obtain them. These stochastic-approximation-type methods utilize gradient estimators based on Infinitesimal Perturbation Analysis or Imbedded Markov Chain techniques. A numerical example demonstrates the performance improvements due to the proposed methods. © 2011 Springer Science+Business Media, LLC.