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Articles 2131 - 2160 of 8897

Full-Text Articles in Physical Sciences and Mathematics

Novel Solid State Lasers Based On Volume Bragg Gratings, Evan Hale Jan 2019

Novel Solid State Lasers Based On Volume Bragg Gratings, Evan Hale

Electronic Theses and Dissertations

Since their invention in 1960, lasers have revolutionized modern technology, and tremendous amounts of innovation and development has gone into advancing their properties and efficiencies. This dissertation reports on further innovations by presenting novel solid state laser systems based on the volume Bragg gratings (VBGs) and the newly developed holographic phase mask (HPMs) for brightness enhancement, dual wavelength operation, and mode conversion. First, a new optical element was created by pairing the HPM with two surface gratings creating an achromatic holographic phase mask. This new optical device successfully performed transverse mode conversion of multiple narrow line laser sources operating from …


Cryogenic Performance Projections For Ultra-Small Oxide-Free Vertical-Cavity Surface-Emitting Lasers, Mina Bayat Jan 2019

Cryogenic Performance Projections For Ultra-Small Oxide-Free Vertical-Cavity Surface-Emitting Lasers, Mina Bayat

Electronic Theses and Dissertations

Small-sized vertical-cavity surface-emitting laser (VCSEL) may offer very low power consumption along with high reliability for cryogenic data transfer. Cryogenic data transfer has application in supercomputers and superconducting for efficient computing and also focal plane array cameras operating at 77 K, and at the lower temperature of 4 K for data extraction from superconducting circuits. A theoretical analysis is presented for 77 K and 4 K operation based on small cavity, oxide-free VCSEL sizes of 2 to 6 µm, that have been shown to operate efficiently at room temperature. Temperature dependent operation for optimally-designed VCSELs are studied by calculating the …


Artificial Magnetism And Topological Phenomena In Optics, Midya Parto Jan 2019

Artificial Magnetism And Topological Phenomena In Optics, Midya Parto

Electronic Theses and Dissertations

Recent years have witnessed intense research activities to effectively control the flow of photons using various classes of optical structures such as photonic crystals and metamaterials. In this regard, optics has benefited from concepts in condensed matter and solid-state physics, where similar problems concerning electronic wavefunctions arise. An important example of such correspondence is associated with the photon dynamics under the effect of an artificial magnetic field. This is especially important since photons, as neutral bosons, do not inherently interact with magnetic fields. One way to mitigate this issue is to exploit magneto-optical materials. However, as is well known, using …


High-Dynamic-Range Foveated Near-Eye Display System, Guanjun Tan Jan 2019

High-Dynamic-Range Foveated Near-Eye Display System, Guanjun Tan

Electronic Theses and Dissertations

Wearable near-eye display has found widespread applications in education, gaming, entertainment, engineering, military training, and healthcare, just to name a few. However, the visual experience provided by current near-eye displays still falls short to what we can perceive in the real world. Three major challenges remain to be overcome: 1) limited dynamic range in display brightness and contrast, 2) inadequate angular resolution, and 3) vergence-accommodation conflict (VAC) issue. This dissertation is devoted to addressing these three critical issues from both display panel development and optical system design viewpoints. A high-dynamic-range (HDR) display requires both high peak brightness and excellent dark …


Computational Imaging With Limited Photon Budget, Zheyuan Zhu Jan 2019

Computational Imaging With Limited Photon Budget, Zheyuan Zhu

Electronic Theses and Dissertations

The capability of retrieving the image/signal of interest from extremely low photon flux is attractive in scientific, industrial, and medical imaging applications. Conventional imaging modalities and reconstruction algorithms rely on hundreds to thousands of photons per pixel (or per measurement) to ensure enough signal-to-noise (SNR) ratio for extracting the image/signal of interest. Unfortunately, the potential of radiation or photon damage prohibits high SNR measurements in dose-sensitive diagnosis scenarios. In addition, imaging systems utilizing inherently weak signals as contrast mechanism, such as X-ray scattering-based tomography, or attosecond pulse retrieval from the streaking trace, entail prolonged integration time to acquire hundreds of …


Optical Sensing Of Structural Dynamics In Complex Media, Jose Rafael Guzman Sepulveda Jan 2019

Optical Sensing Of Structural Dynamics In Complex Media, Jose Rafael Guzman Sepulveda

Electronic Theses and Dissertations

Quantifying the structural dynamics of complex media is challenging because of the multiple temporal and spatial scales involved. Thanks to the ability to retrieve collective dynamics noninvasively, light scattering-based approaches are often the methods of choice. This dissertation discusses specific features of dynamic light scattering that utilizes spatio-temporal coherence gating. It is demonstrated that this optical fiber-based approach can operate over a large range of optical regimes and it has a number of unique capabilities such as an effective isolation of single scattering, a large sensitivity, and a high collection efficiency. Moreover, the approach also provides means for proper ensemble …


Internet Of Things In Smart Agriculture: Enabling Technologies, Abdul Salam, Syed Shah Jan 2019

Internet Of Things In Smart Agriculture: Enabling Technologies, Abdul Salam, Syed Shah

Faculty Publications

In this paper, an IoT technology research and innovation roadmap for the field of precision agriculture (PA) is presented. Many recent practical trends and the challenges have been highlighted. Some important objectives for integrated technology research and education in precision agriculture are described. Effective IoT based communications and sensing approaches to mitigate challenges in the area of precision agriculture are presented.


Theoretical Analysis Of A Volume Holographic Lens Using Matlab, Sanjay Keshri, Kevin Murphy, Izabela Naydenova, Suzanne Martin Jan 2019

Theoretical Analysis Of A Volume Holographic Lens Using Matlab, Sanjay Keshri, Kevin Murphy, Izabela Naydenova, Suzanne Martin

Conference Papers

Volume holographic lenses have great potential for different types of applications requiring light redirection and beam shaping such as solar light collection and LED light management. For lighting applications using LEDs, it is essential to make a highly efficient optical element to be placed in front of the LED in order to decrease energy losses. For that reason, a careful theoretical analysis of the properties and operation regime of the lens must be carried out at the design stage. The characteristics of focusing Holographic Optical Elements (HOE) depend on many factors including their thickness, spatial frequency, the angular range of …


Mode Transition In Conventional Step-Index Optical Fibers, Xiaokang Lian, Gerald Farrell, Qiang Wu, Wei Han, Fangfang Wei, Yuliya Semenova Jan 2019

Mode Transition In Conventional Step-Index Optical Fibers, Xiaokang Lian, Gerald Farrell, Qiang Wu, Wei Han, Fangfang Wei, Yuliya Semenova

Conference Papers

The discrete self-imaging effect reveals the distinct properties of cladding modes with core modes in step-index optical fibers, as was shown in our previous work [1], where only the linearly polarized LP0n modes were studied. In this paper, the dispersion diagram of the first 17 vector modes (TE0n, TM0n, HEmn and EHmn) and the related first 9 LPmn modes are calculated by both the full-vector finite element method and the graphical method with a three-layer step-index optical fiber model. The cladding modes distributions and the transitions between the core and cladding modes are analyzed. The results of this work are …


Sensing Of Multiple Parameters With Whispering Gallery Mode Optical Fiber Micro-Resonators, Arun Kumar Mallik Dr, Vishnan Kavungal, Gerald Farrell, Yuliya Semenova Jan 2019

Sensing Of Multiple Parameters With Whispering Gallery Mode Optical Fiber Micro-Resonators, Arun Kumar Mallik Dr, Vishnan Kavungal, Gerald Farrell, Yuliya Semenova

Conference Papers

Monitoring of multiple physical parameters, such as humidity, temperature, strain, concentrations of certain chemicals or gases in various environments is of great importance in many industrial applications both for minimizing adverse effects on human health as well as for maintaining production levels and quality of products. In this paper we demonstrate two different approaches to the design of multi-parametric sensors using coupled whispering gallery mode (WGM) optical fiber micro-resonators. In the first approach, a small array of micro-resonators is coupled to a single fiber taper, while in the second approach each of the micro-resonators within an array is coupled to …


Transmission Electron Microscopy Analysis Of Silicon-Doped Beta-Gallium Oxide Films Grown By Pulsed Laser Deposition, Cynthia Thomason Bowers Jan 2019

Transmission Electron Microscopy Analysis Of Silicon-Doped Beta-Gallium Oxide Films Grown By Pulsed Laser Deposition, Cynthia Thomason Bowers

Browse all Theses and Dissertations

Due to the large band gap of β-Ga2O3 and recent improvements toward high quality native substrates and the ability to shallow dope epitaxial β-Ga2O3 it is an attractive material for applications in power electronic devices. Such devices require advances in the areas of thin film growth and carrier concentration control to deliver high mobility films appropriate for the device structures. Transmission electron microscopy (TEM) analysis can provide information concerning doping, crystal structure, and internal strain which will be valuable to assess the role of defects and impurities on the transport properties for feedback to optimize the bulk and epitaxial growth …


Gacnn Sleeptunenet: A Genetic Algorithm Designing The Convolutional Neural Network Architecture For Optimal Classification Of Sleep Stages From A Single Eeg Channel, Shahnawaz Qureshi, Seppo Karilla, Sirirut Vanichayobon Jan 2019

Gacnn Sleeptunenet: A Genetic Algorithm Designing The Convolutional Neural Network Architecture For Optimal Classification Of Sleep Stages From A Single Eeg Channel, Shahnawaz Qureshi, Seppo Karilla, Sirirut Vanichayobon

Turkish Journal of Electrical Engineering and Computer Sciences

This study presents a method for designing--by a genetic algorithm, without manual intervention--the feature learning architecture for classification of sleep stages from a single EEG channel, when using a convolutional neural network called GACNN SleepTuneNet. Two EEG electrode positions were selected, namely FP2-F4 and FPz-Cz, from two available datasets. Twenty-five generations were involved in diagnosis without hand-crafted features, to learn the architecture for classification of sleep stages based on AASM standard. Based on the results, our model not only achieved the highest classification accuracy, but it also distinguished the sleep stages based on either of the two EEG electrode signals, …


Design And Fabrication Of A Dual-Polarized, Dual-Band Reflectarray Using Optimal Phase Distribution, Iman Aryanian, Arash Ahmadi, Mehdi Rabbani, Sina Hassibi, Majid Karimipour Jan 2019

Design And Fabrication Of A Dual-Polarized, Dual-Band Reflectarray Using Optimal Phase Distribution, Iman Aryanian, Arash Ahmadi, Mehdi Rabbani, Sina Hassibi, Majid Karimipour

Turkish Journal of Electrical Engineering and Computer Sciences

Two main factors limiting the reflectarray bandwidth are different phase slopes versus the frequency at every point on the aperture and the phase limitation of comprising elements at different frequencies. Considering these two factors, a novel design method is proposed to implement a dual-band, dual-polarized reflectarray antenna in X and Ku bands. An optimization algorithm is adopted to find the optimum phase for each unit cell on the reflectarray aperture. The best geometrical parameters of the phasing elements are suggested based on the phase variation of the element versus frequency and the element position with respect to the antenna feed. …


A New Approach For Wind Turbine Placement Problem Using Modified Differential Evolution Algorithm, Hüseyi̇n Hakli Jan 2019

A New Approach For Wind Turbine Placement Problem Using Modified Differential Evolution Algorithm, Hüseyi̇n Hakli

Turkish Journal of Electrical Engineering and Computer Sciences

Energy use is increasing worldwide with industrialization and advancing technology. Following this increase, renewable energy resources are increasingly preferred to reduce the costs of energy production. Wind energy is preferred as a renewable energy resource because it is clean and safe. Wind turbines are used to meet the demand for wind energy. They are placed close to each other to generate higher amounts of energy. However, the wake effect problem arises in these types of layouts, and this hinders the turbines from producing the desired yield. A modified differential evolution (MDE) algorithm was proposed in this study to solve the …


A Transmission Optimization Algorithm For Smart Load Controllers, Ohyoung Song Jan 2019

A Transmission Optimization Algorithm For Smart Load Controllers, Ohyoung Song

Turkish Journal of Electrical Engineering and Computer Sciences

This paper introduces a transmission optimization algorithm for wireless transmissions between smart load controllers and a corresponding gateway in wireless personal area networks, where smart load controllers connect several electrical appliances through their corresponding load interfaces, measure the power consumption from each electrical appliance connected to the load controller, and control on/off switching through its load interface. The aim of this paper is to reduce the traffic load of power consumption data in electrical appliances used in the building area network and the smart grid network. The proposed algorithm allows the smart load controller to efficiently reduce traffic load even …


Software Defined Networks Based Smart Grid Communication: A Comprehensive Survey, Mubashir Husain Rehmani, Alan Davy, Brendan Jennings, Chadi Assi Jan 2019

Software Defined Networks Based Smart Grid Communication: A Comprehensive Survey, Mubashir Husain Rehmani, Alan Davy, Brendan Jennings, Chadi Assi

Publications

The current power grid is no longer a feasible solution due to ever-increasing user demand of electricity, old infrastructure, and reliability issues and thus require transformation to a better grid a.k.a., smart grid (SG). The key features that distinguish SG from the conventional electrical power grid are its capability to perform two-way communication, demand side management, and real time pricing. Despite all these advantages that SG will bring, there are certain issues which are specific to SG communication system. For instance, network management of current SG systems is complex, time consuming, and done manually. Moreover, SG communication (SGC) system is …


Exploring Gated Nanoelectronic Devices Fabricated From 1d And 2d Materials, Prathamesh A. Dhakras Jan 2019

Exploring Gated Nanoelectronic Devices Fabricated From 1d And 2d Materials, Prathamesh A. Dhakras

Legacy Theses & Dissertations (2009 - 2024)

One and two dimensional materials are being extensively researched toward potential application as ultra-thin body channel materials. The difficulty of implementing physical doping methods in these materials has necessitated various alternative doping schemes, the most promising of which is the electrostatic gating technique due to its reconfigurability. This dissertation explores the different fundamental devices that can be fabricated and characterized by taking advantage of the electrostatic gating of individual single-walled carbon nanotubes (SWNTs), dense SWNT networks and exfoliated 2D tungsten diselenide (WSe2) flakes.


Inception: Virtual Space In Memory Space In Real Space, Peter Casey, Rebecca Lindsay-Decusati, Ibrahim Baggili, Frank Breitinger Jan 2019

Inception: Virtual Space In Memory Space In Real Space, Peter Casey, Rebecca Lindsay-Decusati, Ibrahim Baggili, Frank Breitinger

Electrical & Computer Engineering and Computer Science Faculty Publications

Virtual Reality (VR) has become a reality. With the technology's increased use cases, comes its misuse. Malware affecting the Virtual Environment (VE) may prevent an investigator from ascertaining virtual information from a physical scene, or from traditional “dead” analysis. Following the trend of antiforensics, evidence of an attack may only be found in memory, along with many other volatile data points. Our work provides the primary account for the memory forensics of Immersive VR systems, and in specific the HTC Vive. Our approach is capable of reconstituting artifacts from memory that are relevant to the VE, and is also capable …


Active Recall Networks For Multiperspectivity Learning Through Shared Latent Space Optimization, Theus Aspiras, Ruixu Liu, Vijayan K. Asari Jan 2019

Active Recall Networks For Multiperspectivity Learning Through Shared Latent Space Optimization, Theus Aspiras, Ruixu Liu, Vijayan K. Asari

Electrical and Computer Engineering Faculty Publications

Given that there are numerous amounts of unlabeled data available for usage in training neural networks, it is desirable to implement a neural network architecture and training paradigm to maximize the ability of the latent space representation. Through multiple perspectives of the latent space using adversarial learning and autoencoding, data requirements can be reduced, which improves learning ability across domains. The entire goal of the proposed work is not to train exhaustively, but to train with multiperspectivity. We propose a new neural network architecture called Active Recall Network (ARN) for learning with less labels by optimizing the latent space. This …


Antenna Selection And Transmission Power For Energy Efficiency In Downlink Massive Mimo Systems, Adeeb Salh, Lukman Audah, Nor Shahida Mohd Shah, Shipun Anuar Hamzah, Hasan Saeed Mir Jan 2019

Antenna Selection And Transmission Power For Energy Efficiency In Downlink Massive Mimo Systems, Adeeb Salh, Lukman Audah, Nor Shahida Mohd Shah, Shipun Anuar Hamzah, Hasan Saeed Mir

Turkish Journal of Electrical Engineering and Computer Sciences

Massive multiinput-multioutput (M-MIMO) systems are crucial for maximizing energy efficiency (EE) in fifth-generation (5G) wireless networks. A M-MIMO system's achievable high data rate is highly related to the number of antennas, but increasing the number of antennas the system raises energy consumption. In this paper, we derive ergodic EE based on the optimal transmit power and joint optimization antenna selection (AS) with impact pilot reuse sequences (PRSs). We apply Newton's method and the Lagrange multiplier to derive jointly optimized AS and optimal transmission power under the effect of PRSs. The proposed algorithm prevents repeated searching for joint optimal AS and …


Design Of A Substrate Integrated Waveguide Matrix Amplifier, Shabnam Ahamadi Andevari, Gholamreza Moradi Jan 2019

Design Of A Substrate Integrated Waveguide Matrix Amplifier, Shabnam Ahamadi Andevari, Gholamreza Moradi

Turkish Journal of Electrical Engineering and Computer Sciences

Developments in microwave systems have increased the need for matrix amplifiers, which provide both high gain and wide frequency bands. The aim of this paper is to design a novel 2x4 matrix amplifier with a substrate integrated waveguide (SIW)-based power divider and combiner and a microstrip gain equalizer in the X and low Ku frequency bands. The proposed amplifier can be easily integrated with any microstrip, rectangular waveguide, or SIW-based circuits. The analysis and design of the amplifier is performed using two full wave simulators with different computational techniques (finite element method and finite integration technique) to verify the results. …


Global Stabilization Of A Class Of Fractional-Order Delayed Bidirectional Associativememory Neural Networks, Zhanying Yang, Xiaoyun Tang, Jie Zhang Jan 2019

Global Stabilization Of A Class Of Fractional-Order Delayed Bidirectional Associativememory Neural Networks, Zhanying Yang, Xiaoyun Tang, Jie Zhang

Turkish Journal of Electrical Engineering and Computer Sciences

This paper focuses on the stabilization problem of a class of fractional-order bidirectional associative memory neural networks with time delays. Based on feedback control, a sufficient condition is derived to achieve the global stabilization of systems by using the fractional inequality, the Lyapunov stability theory, and the comparison principle. In particular, this kind of control scheme is proved to be robust in the presence of external disturbances when the feedback gains are sufficiently large. In addition, a condition is obtained to achieve the global quasi-stabilization of systems with some external disturbances, and the corresponding error bound is estimated. Finally, some …


Increasing Bluetooth Low Energy Communication Efficiency By Presetting Protocol Parameters, Dusan Hatvani, Dominik Macko Jan 2019

Increasing Bluetooth Low Energy Communication Efficiency By Presetting Protocol Parameters, Dusan Hatvani, Dominik Macko

Turkish Journal of Electrical Engineering and Computer Sciences

Standard protocols are important regarding the compatibility of devices provided by different vendors. However, specific applications have various requirements and do not always need all features offered by standard protocols, making them inefficient. This paper focuses on standard Bluetooth Low Energy modifications, reducing control overhead for the intended healthcare application. Specifically, the connection establishment, device pairing, and connection parameter negotiations have been targeted. The simulation-based experiments showed over 20 times reduction of control-overhead time preceding a data transmission. It does not just directly increase the energy efficiency of communication; it also prolongs the time for sensor-based end devices to spend …


Enhancing Face Pose Normalization With Deep Learning, Anil Çeli̇k, Nafi̇z Arica Jan 2019

Enhancing Face Pose Normalization With Deep Learning, Anil Çeli̇k, Nafi̇z Arica

Turkish Journal of Electrical Engineering and Computer Sciences

In this study, we propose a hybrid method for face pose normalization, which combines the 3-D model-based method with stacked denoising autoencoder (SDAE) deep network. Instead of applying a mirroring operation for the invisible face parts of the posed image, SDAE learns how to fill in those regions by a large set of training samples. In the performance evaluation, we compare the proposed method to four different pose normalization methods and investigate their effects on facial emotion recognition and verification problems in addition to visual quality tests. Methods evaluated in the experiments include 2-D alignment, 3-D model-based method, pure SDAE-based …


Sentence Similarity Using Weighted Path And Similarity Matrices, Reza Javadzadeh, Morteza Zahedi, Marziea Rahimi Jan 2019

Sentence Similarity Using Weighted Path And Similarity Matrices, Reza Javadzadeh, Morteza Zahedi, Marziea Rahimi

Turkish Journal of Electrical Engineering and Computer Sciences

Sentence similarity is the task of assessing how similar the two snippets of text are. Similarity techniques are used extensively in clustering, summarization, classification, plagiarism detection etc. Due to a small set of vocabularies, sentence similarity is considered to be a difficult problem in natural language processing. There are two issues in solving this problem: (1) Which similarity techniques to be used for word pair similarity and (2) How to generalize that to sentence pairs. We have used the weighted path, a WordNet-based similarity assessment, and the paraphrase database to obtain word pair similarity values. Thereafter, we extracted maximum values …


Application Of Fuzzy Logic On Astronomical Images' Focus Measures, Alaa Hamdy, Farag Elnagahy, Islam Helmy Jan 2019

Application Of Fuzzy Logic On Astronomical Images' Focus Measures, Alaa Hamdy, Farag Elnagahy, Islam Helmy

Turkish Journal of Electrical Engineering and Computer Sciences

Focus accuracy is an essential factor that affects the quality of astronomical observations. The accurate measurement of celestial objects' properties depends on focus. Automatic focusing is necessary for celestial imaging systems. This paper presents a modified focus measure operator. It also proposes the use of fuzzy logic to transform images because of its tolerance of imprecise and incomplete data. The focus operators are applied to two sequences of star clusters' observations. The experimental results show that the suggested measure's overall score exceeds those of previous operators.


Research On The Dynamic Networking Of Smart Meters Based On Characteristics Of The Collected Data, Yaxin Huang, Yunlian Sun, Xiaodi Zhang Jan 2019

Research On The Dynamic Networking Of Smart Meters Based On Characteristics Of The Collected Data, Yaxin Huang, Yunlian Sun, Xiaodi Zhang

Turkish Journal of Electrical Engineering and Computer Sciences

In order to accurately collect the electricity usage information from the smart meter which uses the power line for communication, this paper proposes the method of dynamic networking to enhance the reliability of the smart meter communication. We shall firstly establish a logical topology between the smart meter and the concentrator with reference to their communication paths within the power supply range of the same transformer, and then grade smart meters, and choose the relay for each level network based on the selection methods of relay, and finally use the improved ant colony algorithm to choose the optimal communication path …


A Novel Map-Merging Technique For Occupancy Grid-Based Maps Using Multiple Robots: A Semantic Approach, Aki̇f Durdu, Mehmet Korkmaz Jan 2019

A Novel Map-Merging Technique For Occupancy Grid-Based Maps Using Multiple Robots: A Semantic Approach, Aki̇f Durdu, Mehmet Korkmaz

Turkish Journal of Electrical Engineering and Computer Sciences

Map merging is a noteworthy phenomenon for cases such as search and rescue and disaster areas in which the duration is quite significant when gathering information about an environment. It is obvious that the total mapping time decreases if the number of agents (robots) increases. However, the use of multiple agents leads to problems such as task allocation schemes and the fusing of local maps. Examining the present methods, it is generally observed that the common features of local maps have been found and the global map is formed by obtaining related transformation between local maps. However, such implementations may …


A Distributed Load Balancing Algorithm For Deduplicated Storage, Prabavathy Balasundaram, Chitra Babu, Pradeep Rengaswamy Jan 2019

A Distributed Load Balancing Algorithm For Deduplicated Storage, Prabavathy Balasundaram, Chitra Babu, Pradeep Rengaswamy

Turkish Journal of Electrical Engineering and Computer Sciences

While deduplication brings the advantage of significant space savings in storage, it nevertheless incurs the overhead of maintaining huge metadata. Updating such huge metadata during the data migration that arises due to load balancing activity results in significant overhead. In order to reduce this metadata update overhead, this paper proposes a suitable alternate index that tracks the data blocks even when they migrate across the nodes without explicitly storing the location information. In addition, a virtual server-based load balancing (VSLB) algorithm has been proposed in order to reduce the migration overhead. The experimental results indicate that the proposed index reduces …


A New Model To Determine The Hierarchical Structure Of The Wireless Sensor Networks, Resmi̇ye Nasi̇boğlu, Zülküf Teki̇n Erten Jan 2019

A New Model To Determine The Hierarchical Structure Of The Wireless Sensor Networks, Resmi̇ye Nasi̇boğlu, Zülküf Teki̇n Erten

Turkish Journal of Electrical Engineering and Computer Sciences

Wireless sensor networks are one of the rising areas of scientific research. Common purpose of these investigations is usually constructing optimal structure of the network by prolonging its lifetime. In this study, a new model has been proposed to construct a hierarchical structure of wireless sensor networks. Methods used in the model to determine clusters and appropriate cluster heads are k-means clustering and fuzzy inference system (FIS), respectively. The weighted averaging based on levels (WABL) defuzzification method is used to calculate crisp outputs of the FIS. A new theorem for calculation of WABL values has been proved in order to …