Browsing by Subject "Forestry"

Now showing 1 - 13 of 13

Open Access
3D forest fire propagation simulation
(IEEE, 2008-05) Köse, Kıvanç; Grammalidis, N.; Yılmaz, E.; Çetin, A. Enis
The increase in the number of forest fires in the last few years dispatch governments to take precautions. Besides prevention, early intervention is also very important in fire fighting. If the firefighters know where the fire will be in some time, it would be easier for them to stop the fire. Therefore a big need for simulating the fire behavior exists. In this paper we are proposing a system which can simulate the propagation of fire in time. Also this system can visualize the propagation of fire in any 3D-GIS environment, that accepts KMZ as a file format. Besides, any user demanded data can be visualized on the map of the system. This gives the chance of fire planning to firefighters. The system can visualize its results on 3D screens in 3D. Therefore, a better understanding of the terrain can be obtained. ©2008 IEEE.
Open Access
Adaptive and efficient nonlinear channel equalization for underwater acoustic communication
(Elsevier B.V., 2017) Kari, D.; Vanli, N. D.; Kozat, S. S.
We investigate underwater acoustic (UWA) channel equalization and introduce hierarchical and adaptive nonlinear (piecewise linear) channel equalization algorithms that are highly efficient and provide significantly improved bit error rate (BER) performance. Due to the high complexity of conventional nonlinear equalizers and poor performance of linear ones, to equalize highly difficult underwater acoustic channels, we employ piecewise linear equalizers. However, in order to achieve the performance of the best piecewise linear model, we use a tree structure to hierarchically partition the space of the received signal. Furthermore, the equalization algorithm should be completely adaptive, since due to the highly non-stationary nature of the underwater medium, the optimal mean squared error (MSE) equalizer as well as the best piecewise linear equalizer changes in time. To this end, we introduce an adaptive piecewise linear equalization algorithm that not only adapts the linear equalizer at each region but also learns the complete hierarchical structure with a computational complexity only polynomial in the number of nodes of the tree. Furthermore, our algorithm is constructed to directly minimize the final squared error without introducing any ad-hoc parameters. We demonstrate the performance of our algorithms through highly realistic experiments performed on practical field data as well as accurately simulated underwater acoustic channels. © 2017 Elsevier B.V.
Open Access
Data imputation through the identification of local anomalies
(Institute of Electrical and Electronics Engineers Inc., 2015) Ozkan, H.; Pelvan, O. S.; Kozat, S. S.
We introduce a comprehensive and statistical framework in a model free setting for a complete treatment of localized data corruptions due to severe noise sources, e.g., an occluder in the case of a visual recording. Within this framework, we propose: 1) a novel algorithm to efficiently separate, i.e., detect and localize, possible corruptions from a given suspicious data instance and 2) a maximum a posteriori estimator to impute the corrupted data. As a generalization to Euclidean distance, we also propose a novel distance measure, which is based on the ranked deviations among the data attributes and empirically shown to be superior in separating the corruptions. Our algorithm first splits the suspicious instance into parts through a binary partitioning tree in the space of data attributes and iteratively tests those parts to detect local anomalies using the nominal statistics extracted from an uncorrupted (clean) reference data set. Once each part is labeled as anomalous versus normal, the corresponding binary patterns over this tree that characterize corruptions are identified and the affected attributes are imputed. Under a certain conditional independency structure assumed for the binary patterns, we analytically show that the false alarm rate of the introduced algorithm in detecting the corruptions is independent of the data and can be directly set without any parameter tuning. The proposed framework is tested over several well-known machine learning data sets with synthetically generated corruptions and experimentally shown to produce remarkable improvements in terms of classification purposes with strong corruption separation capabilities. Our experiments also indicate that the proposed algorithms outperform the typical approaches and are robust to varying training phase conditions. © 2015 IEEE.
Open Access
Dynamic point-region quadtrees for particle simulations
(Elsevier Inc., 2013) Oğuz, O.; Durupınar, F.; Güdükbay, Uğur
We propose an algorithm for dynamically updating point-region (PR) quadtrees. Our algorithm is optimized for simultaneous update of data points comprising a quadtree. The intended application area focuses on simulating continuum phenomena, such as crowds, fluids, and smoke. We minimize the number of tree updates by making use of small changes in the positions of data points. We compare the efficiency of the proposed algorithm with two other approaches for updating a quadtree. One of these techniques creates the tree from scratch at each time-step. The second technique subsequently deletes a data point from the tree and reinserts it in its updated position. We achieve significant performance gains with our method in both cases. © 2012 Elsevier Inc. All rights reserved.
Open Access
Exact and heuristic approaches based on noninterfering transmissions for joint gateway selection, time slot allocation, routing and power control for wireless mesh networks
(Elsevier, 2017) Gokbayrak, K.; Yıldırım, E. A.
Wireless mesh networks (WMNs) provide cost-effective alternatives for extending wireless communication over larger geographical areas. In this paper, given a WMN with its nodes and possible wireless links, we consider the problem of gateway node selection for connecting the network to the Internet along with operational problems such as routing, wireless transmission capacity allocation, and transmission power control for efficient use of wired and wireless resources. Under the assumption that each node of the WMN has a fixed traffic rate, our goal is to allocate capacities to the nodes in proportion to their traffic rates so as to maximize the minimum capacity-to-demand ratio, referred to as the service level. We adopt a time division multiple access (TDMA) scheme, in which a time frame on the same frequency channel is divided into several time slots and each node can transmit in one or more time slots. We propose two mixed integer linear programming formulations. The first formulation, which is based on individual transmissions in each time slot, is a straightforward extension of a previous formulation developed by the authors for a related problem under a different set of assumptions. The alternative formulation, on the other hand, is based on sets of noninterfering wireless transmissions. In contrast with the first formulation, the size of the alternative formulation is independent of the number of time slots in a frame. We identify simple necessary and sufficient conditions for simultaneous transmissions on different links of the network in the same time slot without any significant interference. Our characterization, as a byproduct, prescribes a power level for each of the transmitting nodes. Motivated by this characterization, we propose a simple scheme to enumerate all sets of noninterfering transmissions, which is used as an input for the alternative formulation. We also introduce a set of valid inequalities for both formulations. For large instances, we propose a three-stage heuristic approach. In the first stage, we solve a partial relaxation of our alternative optimization model and determine the gateway locations. This stage also provides an upper bound on the optimal service level. In the second stage, a routing tree is constructed for each gateway node computed in the first stage. Finally, in the third stage, the alternative optimization model is solved by fixing the resulting gateway locations and the routing trees from the previous two stages. For even larger networks, we propose a heuristic approach for solving the partial relaxation in the first stage using a neighborhood search on gateway locations. Our computational results demonstrate the promising performance of our exact and heuristic approaches and the valid inequalities
Open Access
Fall detection using single-tree complex wavelet transform
(Elsevier, 2013) Yazar, A.; Keskin, F.; Töreyin, B. U.; Çetin, A. Enis
The goal of Ambient Assisted Living (AAL) research is to improve the quality of life of the elderly and handicapped people and help them maintain an independent lifestyle with the use of sensors, signal processing and telecommunications infrastructure. Unusual human activity detection such as fall detection has important applications. In this paper, a fall detection algorithm for a low cost AAL system using vibration and passive infrared (PIR) sensors is proposed. The single-tree complex wavelet transform (ST-CWT) is used for feature extraction from vibration sensor signal. The proposed feature extraction scheme is compared to discrete Fourier transform and mel-frequency cepstrum coefficients based feature extraction methods. Vibration signal features are classified into "fall" and "ordinary activity" classes using Euclidean distance, Mahalanobis distance, and support vector machine (SVM) classifiers, and they are compared to each other. The PIR sensor is used for the detection of a moving person in a region of interest. The proposed system works in real-time on a standard personal computer.
Open Access
Fire detection and 3D fire propagation estimation for the protection of cultural heritage areas
(Copernicus GmbH, 2010) Dimitropoulos, K.; Köse, Kıvanç; Grammalidis, N.; Çetin, A. Enis
Beyond taking precautionary measures to avoid a forest fire, early warning and immediate response to a fire breakout are the only ways to avoid great losses and environmental and cultural heritage damages. To this end, this paper aims to present a computer vision based algorithm for wildfire detection and a 3D fire propagation estimation system. The main detection algorithm is composed of four sub-algorithms detecting (i) slow moving objects, (ii) smoke-coloured regions, (iii) rising regions, and (iv) shadow regions. After detecting a wildfire, the main focus should be the estimation of its propagation direction and speed. If the model of the vegetation and other important parameters like wind speed, slope, aspect of the ground surface, etc. are known; the propagation of fire can be estimated. This propagation can then be visualized in any 3D-GIS environment that supports KML files.
Restricted
Köy Hizmetleri Genel Müdürlüğü ve kırsal kalkınma faaliyetleri
(Bilkent University, 2021) Ayaz, Eda İrem; Budak, Yağmur; Özbay, Ece; Özdemir, Aslı Zeynep; Özlü, Arda
Köy Hizmetleri Genel Müdürlüğü 1984 yılında kırsal kalkınmayı desteklemesi, köy yollarının onarımı ve geliştirilmesi ve köylere elektrik ve içme suyu sağlanması gibi birçok hizmeti vermesi amacıyla kurulmuştur. Bu kurum, kırsal kalkınma bağlamında birçok proje ve çalışmaya imza atmıştır ve aktif olduğu seneler içerisinde sürekli olarak gelişimini sürdürmüştür. Hizmetlerini ülke genelinde sürdüren genel müdürlük 2005 yılında yerel çalışmalara ağırlık verilebilmesi için kapatılmıştır ve yetkileri il özel idarelerine devredilmiştir.
Open Access
A performance comparison of zone-based multicast protocols for mobile ad hoc networks
(IEEE, 2003) Zhang, Y.; Rangnekar, A.; Selçuk, Ali A.; Bicak, A.; Sidhu, D.
With the current trend toward ubiquitous computing come wireless devices capable of forming the nodes of mobile ad hoc networks. Such networks typically rely on routing protocols in order to communicate messages from a source node to a destination node through a set of intermediary nodes. In a typical ad hoc environment, mobile nodes mostly work as a group and are involved in collaborative computing. Multicast communication is more effective in these scenarios. This paper presents the comparison of the performance of two zone-based multicast routing protocols. Shared-tree MZR is a shared tree variant of the Multicast Routing Protocol based on Zone Routing (MZR). We compare the two variants and analyze their performance under various network conditions. The test results show that Shared-tree MZR protocol performs well and has significantly low overhead in scenarios with multiple sources. ©2003 IEEE.
Open Access
PSAR: Power-source-aware routing in ZigBee networks
(2012) Tekkalmaz, M.; Korpeoglu I.
ZigBee is a recent wireless networking technology built on IEEE 802.15.4 standard and designed especially for low-data rate and low-duty cycle applications such as home and building automation and sensor networks. One of the primary goals of ZigBee is low power consumption and therefore long-living networks. Despite this goal, current network formation and routing protocols described in the ZigBee specification do not fully address power consumption issues. In this work, we propose a distributed routing algorithm to reduce power consumption of battery-powered devices by routing the communication through mains-powered devices whenever possible and consequently increasing the overall network lifetime. The proposed algorithm works on tree topologies supported by ZigBee and requires only minor modifications to the current specification. Our ns-2 simulation results showed that the algorithm is able to reduce the power consumption of battery-powered devices significantly with minimal communication overhead. © Springer Science+Business Media, LLC 2012.
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Time-varying lifting structures for single-tree complexwavelet transform
(IEEE, 2012) Keskin, Furkan; Çetin, A. Enis
In this paper, we describe a single-tree complex wavelet transform method using time-varying lifting structures. In the dualtree complex wavelet transform (DT-CWT), two different filterbanks are executed in parallel to analyze a given input signal, which increases the amount of data after analysis. DT-CWT leads to a redundancy factor of 2 d for d-dimensional signals. In the proposed single-tree complex wavelet transform (ST-CWT) structure, filters of the lifting filterbank switch back and forth between the two analysis filters of the DT-CWT. This approach does not increase the amount of output data as it is a critically sampled transform and it has the desirable properties of DT-CWT such as shift-invariance and directional selectivity. The proposed filterbank is capable of constructing a complex wavelet-like transform. Examples are presented. © 2012 IEEE.
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Türkiye Orman Teşkilatı'nın tarihi ve gelişimi
(Bilkent University, 2020) Acer, Ahsen Rana; Özcan, Büşra Nur; Özyürek, Doruk Can; Kaman, Gökçe; Uygun, Muhammed
Türkiye Orman Teşkilatı, kuruluşundan günümüze kadar çeşitli reformlara tanıklık etmiştir. Bu kapsamda Cumhuriyet Dönemi öncesinde atılan adımlar ve Cumhuriyet'in kuruluş aşamasının ardından çıkarılan kanunlar bu teşkilatın günümüzdeki hâlini almasında etkili olmuştur. Özellikle bilimsel ve teknik anlamda ormancılığın başlamasının ardından modern ormancılığın temelleri oluşturulmuş ve devletin ormanları-halkın ormanları tartışmasına da son verilmiştir. Atılan bu adımla birlikte Ormancılık alanında tam anlamıyla bir teşkilatlanma başlamıştır ve Türkiye Ormanları güvence altına alınmıştır. Çevrenin korunmasında ve kerestecilik gibi faaliyetlerin yürütülmesine sağladığı katkıları ile ülke ekonomisinde de önemli bir yere sahip olan bu teşkilat günümüzde ise Orman Bakanlığına bağlı bir genel müdürlük olarak hâlen varlığını sürdürmektedir.
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Türkiye Ormancılar Derneği
(Bilkent University, 2020) Sefercik, Recep; Öztürk, Ünsal; Baykara, Oğuzhan; Yıldız, Tanıl; Tümer, Dilek Şevval
Türkiye Ormancılar Derneği, Türkiye'nin en eski sivil tabanlı derneklerinden biridir, ve kökleri kurulduğu 1924 yılına kadar gitmektedir. Tarihsel olarak, dernek Türk ormancılığı üzerindeki en önemli etkenlerden biri olmuştur. Derneğin tarihi nitelik taşıyan faaliyetleri arasında 1950'lerde bugün adı ODTÜ ormanı olarak bilinen Atatürk Ormanı'nın kurulması, orman işletmeciliği ve ormancılık hakkındaki çeşitli yasaların çıkarılması ve özel sektörün ormancılık bağlamında ormanlara ne kadar müdahale edebileceğinin sınırlarının çizilmesi gibi çalışmalar yer almaktadır.