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2019

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Articles 8251 - 8280 of 10505

Full-Text Articles in Engineering

An Investigation Into The Impact Of Social Networking On Knowledge Sharing, James Harold Gorham Jan 2019

An Investigation Into The Impact Of Social Networking On Knowledge Sharing, James Harold Gorham

CCAC Theses and Dissertations

Today we are experiencing a rapidly increasing trend to use social networking in ways that dramatically affect both our personal and our public lives. This is a global phenomenon being experienced around the world. Exactly how this technology is being used and by whom is of great interest. The problem is that not a lot of research has been conducted to investigate the role social networking sites play to influence a person’s attitude toward sharing knowledge at work. In light of the marked increase in the use of social networking sites and how it is changing the way we live, …


Comprehending The Safety Paradox And Privacy Concerns With Medical Device Remote Patient Monitoring, Marc Doyle Jan 2019

Comprehending The Safety Paradox And Privacy Concerns With Medical Device Remote Patient Monitoring, Marc Doyle

CCAC Theses and Dissertations

Medical literature identifies a number of technology-driven improvements in disease management such as implantable medical devices (IMDs) that are a standard treatment for candidates with specific diseases. Among patients using implantable cardiac defibrillators (ICD), for example, problems and issues are being discovered faster compared to patients without monitoring, improving safety. What is not known is why patients report not feeling safer, creating a safety paradox, and why patients identify privacy concerns in ICD monitoring.

There is a major gap in the literature regarding the factors that contribute to perceived safety and privacy in remote patient monitoring (RPM). To address this …


Examining Pilot Decision Making In Information-Rich Cockpits, Meredith Carroll, Donna Forsyth Wilt, Paige Sanchez, Deborah Carstens Jan 2019

Examining Pilot Decision Making In Information-Rich Cockpits, Meredith Carroll, Donna Forsyth Wilt, Paige Sanchez, Deborah Carstens

Aeronautics Faculty Publications

Pilots are faced with making decisions based on a range of different information sources. One challenge pilots often face is the presentation of conflicting information between sources. This effort examined pilot decision making with conflicting information by conducting structured interviews with 13 pilots, including seven airline, three corporate, and three GA pilots. Pilots were asked questions regarding their experience with conflicting sources of weather, traffic, and navigation information on the flight deck or cockpit. Further, they were asked to describe how they responded to the information conflict, including which source they trusted, which source they ultimately acted on, and why …


Throughput Analysis Of The Ieee 802.11 Dcf In Cognitive Radio Networks, Jun Peng Jan 2019

Throughput Analysis Of The Ieee 802.11 Dcf In Cognitive Radio Networks, Jun Peng

Electrical and Computer Engineering Faculty Publications

This paper presents an analysis estimating the saturation throughput of the IEEE 802.11 Distributed Coordination Function (DCF) in Cognitive Radio (CR) networks. Among the many CR network paradigms, the one where existing wireless networks continue to work in the cognitive radio context is attractive and of great importance for CR study and deployment. The performance of the IEEE 802.11 DCF with cognitive radio thus emerges as an important topic. We present an analytical method based on a Markov chain model to estimate the saturation throughput of the IEEE 802.11 DCF with cognitive radio. We also show simulation results validating the …


Multi-Negative Index Band Metamaterial-Inspired Microfluidic Sensors, Nantakan Wongkasem, Mark Ruiz Jan 2019

Multi-Negative Index Band Metamaterial-Inspired Microfluidic Sensors, Nantakan Wongkasem, Mark Ruiz

Electrical and Computer Engineering Faculty Publications

Simple, compact and high sensitivity metamaterial-inspired microfluid sensors are developed to detect and classify dielectric fluids in the X-band regime using reflection coefficients. Multi-negative refractive index band metamaterial structure is specifically designed as a sensing enhancer, where the multi negative bands can effectively trigger the electromagnetic properties, as well as enhance the differentiation between the testing samples. The geometry of the metamaterial enhancer and its arrangement with the microfluidic channel and radiating patch antenna are optimized to reach the highest sensitivity of the samples' depiction. The proposed sensors were tested on methanol and ethanol traces, where sets of complex permittivity …


Multi-Objective Design Optimization Of A Permanent Magnet Axial Flux Eddy Current Brake, Rasul Tarvirdilu Asl, Hüseyi̇n Murat Yüksel, Ozan Keysan Jan 2019

Multi-Objective Design Optimization Of A Permanent Magnet Axial Flux Eddy Current Brake, Rasul Tarvirdilu Asl, Hüseyi̇n Murat Yüksel, Ozan Keysan

Turkish Journal of Electrical Engineering and Computer Sciences

The main aim of this study is to optimize an axial flux eddy current damper to be used in a specific aviation application. Eddy current dampers are more advantageous compared to conventional mechanical dampers as they are maintenance-free due to contactless structure and have higher reliability, which is very desirable in aerospace applications. An initial eddy current brake prototype is manufactured and the test results are used to verify the 3-D finite element simulations. The effect of temperature on the brake performance is investigated. Finally, a multiobjective genetic algorithm optimization is applied to find the optimum pole number and geometric …


Prioritizing Interdependent Software Requirements Using Tensor And Fuzzy Graphs, Negin Misaghian, Homayun Motameni, Mohsen Rabbani Jan 2019

Prioritizing Interdependent Software Requirements Using Tensor And Fuzzy Graphs, Negin Misaghian, Homayun Motameni, Mohsen Rabbani

Turkish Journal of Electrical Engineering and Computer Sciences

Owing to the special stance of prioritizing tasks in requirements engineering processes, and as the requirements are not independent in nature, considering their dependencies is essential during the prioritizing process. Although different classifications of dependency types among requirements exist, only a few approaches in the prioritization process consider such valuable data (dependency among equirements). To achieve a practical prioritization, this study proposes a method based on the effects of the requirement dependencies (increase/decrease cost of) on the value of prioritization provided by the tensor concept. Since the strengths of dependencies are also influential factors in the act of prioritization, The …


Extraction And Selection Of Statistical Harmonics Features For Electrical Appliancesidentification Using K-Nn Classifier Combined With Voting Rules Method, Fateh Ghazali, Abdenour Hacine-Gharbi, Philippe Ravier, Tayeb Mohamadi Jan 2019

Extraction And Selection Of Statistical Harmonics Features For Electrical Appliancesidentification Using K-Nn Classifier Combined With Voting Rules Method, Fateh Ghazali, Abdenour Hacine-Gharbi, Philippe Ravier, Tayeb Mohamadi

Turkish Journal of Electrical Engineering and Computer Sciences

In this paper, we propose a novel framework for electrical appliances identification using statistical harmonic features of current signals and the use of the k-NN classifier combined with a voting rule strategy. Harmonic coefficients are computed over time using short-time Fourier series of the current signals. From these sequences of coefficients, the mean, standard deviation, skewness, and kurtosis are computed, which provide the statistical harmonic features. This framework has three novelties: (i) selecting the best combination of statistical measures in the sense of classification rate (CR); (ii) combining the k-NN classifier with the voting rule method in order to search …


Softswitch: A Centralized Honeypot-Based Security Approach Using Software-Defined Switching For Secure Management Of Vlan Networks, Muhammet Baykara, Resul Daş Jan 2019

Softswitch: A Centralized Honeypot-Based Security Approach Using Software-Defined Switching For Secure Management Of Vlan Networks, Muhammet Baykara, Resul Daş

Turkish Journal of Electrical Engineering and Computer Sciences

Honeypot systems are traps for intruders which simulate real systems such as web, application, and database servers used in information systems. Using these systems, unauthorized and malicious access can be efficiently detected. Honeypot is an entity which acts as a source of valued information and its behavior can be monitored. The inability or difficulty of intrusion detection is a serious security problem in networks including virtual local area network (VLAN). According to the literature, the use of honeypots for intrusion detection and prevention in networks including VLAN is strongly recommended. In this paper, in order to provide security and to …


Effects Of Geometry And Phase On Material Damage Response Under High-Speed Impact, Rachel Waxman Jan 2019

Effects Of Geometry And Phase On Material Damage Response Under High-Speed Impact, Rachel Waxman

Theses and Dissertations

Peridynamics, presented by Silling in 2000 [1], is a reformulation of the elastic theory from differential equations to integral equations, which are more equipped to handle discontinuities, such as crack initiation and propagation. Because of this, peridynamics is an effective tool to address many of the problems relevant to the aerospace and defense industries. For example, airborne sand particles and raindrops cause local damage to aircraft in flight. This damage manifests itself as radial and subsurface lateral cracking, as well as increased surface roughness. All of these damage morphologies may result in undesired degradation of mechanical and optical properties.

This …


Phase-Only Digital Encryption Using A Three-Pass Protocol, Jonathan Blackledge, Paul Tobin, W. Govere, S. Sibanda, C. M. Adolfo Jan 2019

Phase-Only Digital Encryption Using A Three-Pass Protocol, Jonathan Blackledge, Paul Tobin, W. Govere, S. Sibanda, C. M. Adolfo

Conference papers

Abstract—This paper considers an application of phase-only digital encryption to the three-pass protocol leading to a new ‘nokey- exchange algorithm’. After providing a study on the theoretical background to the method, an algorithm is presented on a step-by-step basis together with three examples of cryptanalysis. A prototype MATLAB function is provided for validation of the approach and for further development by interested readers.


The Chirp Function Revisited: A Uniqueness Conjecture For Chirplet Modulation, Jonathan Blackledge, Paul Tobin Jan 2019

The Chirp Function Revisited: A Uniqueness Conjecture For Chirplet Modulation, Jonathan Blackledge, Paul Tobin

Conference papers

The chirp function (a unit amplitude quadratic phase-only function with linear frequency modulation) is well known and is used in a wide range of applications including radar, digital communications, information coding and hiding and many other forms of signal and image processing. This is because the chirp provides an optimal solution to the problem of retrieving information from low energy signals with a low Signal-to-Noise Ratio (SNR). The chirp function also occurs in the solution to many mathematical models used to describe the propagation and scattering of waves (in the Fresnel zone), in quantum mechanics (the quantum shutter problem) and …


Photovoltaic Supplied T-Type Three- Phase Inverter With Harmonic Current Compensation Capability, Zahera Batool, Samet Biricik, Hasan Komurcugil, Tuan Ngo, Tuyen V. Vu Jan 2019

Photovoltaic Supplied T-Type Three- Phase Inverter With Harmonic Current Compensation Capability, Zahera Batool, Samet Biricik, Hasan Komurcugil, Tuan Ngo, Tuyen V. Vu

Conference papers

In this paper, a T-Type grid-connected inverter with harmonic current compensation capability is proposed and studied for the on-grid photovoltaic (PV) systems. This idea is based on the modification of the existing photovoltaic inverter control algorithm with the adaptation of active power filter control algorithm. The grid-connected PV inverter has similar topology and control methods as that of the active power filter systems. However, such multifunctional inverters have not yet matured for commercial use and call for more research. In this work, a conventional phase locked-loop algorithm is used to determine the angular position of the synchronous reference of the …


Three-Phase Two-Leg T-Type Converter Based Active Power Filter, Samet Biricik, Hasan Komurcugil, Mohamed Trabelsi Jan 2019

Three-Phase Two-Leg T-Type Converter Based Active Power Filter, Samet Biricik, Hasan Komurcugil, Mohamed Trabelsi

Conference papers

In this work, a three-phase two-leg T-type active power filter topology is investigated when a three-level hysteresis band current modulation technique is applied. The three-phase two-leg T-type configuration which utilizes eight switching devices together split DC link capacitor banks is able to improve the reliability of the system as well as effectively reduces the power losses. The compensation of the current harmonics at each phase are achieved successfully with the control of phase-a and phase-b. Using this technique, the phase-c is directly connected to the midpoint of the split capacitors, which eliminates the necessity of additional control on the phase-c. …


Detection Of Grid Voltage Anomalies Via Broadband Subspace Decomposition, Samet Biricik, Soydan Redif Jan 2019

Detection Of Grid Voltage Anomalies Via Broadband Subspace Decomposition, Samet Biricik, Soydan Redif

Conference papers

Due to the increase of sensitive loads on the mains power grid, measurement and monitoring of the power quality (PQ) have become an important factor for both consumers and operators. As is well-known, PQ problems occur in a very short time period with specific characteristics. In transmission or distribution systems, power quality data are collected from monitoring devices such as digital fault recorders, power quality and dynamic system monitors, etc. The recorded data has to be analysed in order to understand system anomalies. These anomalies may be due to sources of broadband noise. In this study, we employ broadband subspace …


Demand Response And Consumer Inconvenience, Chittesh Veni Chandran, Malabika Basu, Keith Sunderland Jan 2019

Demand Response And Consumer Inconvenience, Chittesh Veni Chandran, Malabika Basu, Keith Sunderland

Conference papers

Balancing the energy demand and generation using the latest load management technologies is considered as an immediate requirement for peak demand management and to improve the operation of electrical distribution networks. However, load management technologies depriving consumers of utilizing their personal resources could be perceived as a consumer right violation by many consumers, and thus, the success of the program is significantly dependent on consumer satisfaction. This paper probes consumer engagement plans through an algorithm to minimize the consumer inconvenience caused by the load management/demand response (DR) program. Four different consumer engagement plans are proposed for consumers with different tolerance …


Building A Risk Model For The Patient-Centred Care Of Multiple Chronic Diseases, Stephane Deparis, Pierpaolo Tommasi, Alessandra Pascale, Hicham Rifai, Julie Doyle, John Dinsmore Jan 2019

Building A Risk Model For The Patient-Centred Care Of Multiple Chronic Diseases, Stephane Deparis, Pierpaolo Tommasi, Alessandra Pascale, Hicham Rifai, Julie Doyle, John Dinsmore

Conference papers

With the increase of multimorbidity due to population ageing, managing multiple chronic health conditions is a rising challenge. Machine-learning can contribute to a better understanding of persons with multimorbidity (PwMs) and how to design an effective framework of care and support for them. We present a risk model of older PwMs that was derived from the TILDA dataset, a longitudinal study of the ageing Irish population. This model is based on a 26-nodes Bayesian network that represents patients possibly having one or more chronic conditions among diabetes, chronic obstructive pulmonary disease and arthritis, through a joint probability distribution of demographic, …


Third-Order Optical Nonlinearity Properties Of Cdcl2-Modifed Ge–Sb–S Chalcogenide Glasses, Xiaosong Lu, Jianhui Li, Lu Yang, Runan Zhang, Yindong Zhang, Jing Ren, Aurelian Catalin Galca, Mihail Secu, Gerald Farrell, Pengfei Wang Jan 2019

Third-Order Optical Nonlinearity Properties Of Cdcl2-Modifed Ge–Sb–S Chalcogenide Glasses, Xiaosong Lu, Jianhui Li, Lu Yang, Runan Zhang, Yindong Zhang, Jing Ren, Aurelian Catalin Galca, Mihail Secu, Gerald Farrell, Pengfei Wang

Articles

We developed a new type of chalcohalide glasses with physicochemical and nonlinear optical properties that are tunable by composition. It is found that more than 60 mol.% CdCl2 heavy metal halide can be dissolved into the ternary Ge–Sb–S system and forming stable glasses. The visible-light transparency range is extended to shorter wavelengths with the addition of CdCl2, which is beneficial for the optical quality control and infra-red (IR) system alignment. The third-order optical nonlinearity (TONL) is studied using the femtosecond Z-scan method. The results show that both the nonlinear refractive index and two photon absorption co-efficient decrease with CdCl2. Benefiting …


Teaching Technical Communication To Engineering Students: Design, Implementation, And Assessment For Project-Based Instruction, Yang Gao Jan 2019

Teaching Technical Communication To Engineering Students: Design, Implementation, And Assessment For Project-Based Instruction, Yang Gao

Proceedings of the Interdisciplinary STEM Teaching & Learning Conference (Archived)

Through the project-based instruction (PBI) method, this paper described the design, implementation, and assessment of a technical communication course for engineering graduate students. The paper first addressed an increasing demand of engineering students with great communication skills through analyzing the existing literature and industry criteria. It then introduced concepts and characteristics of PBI and explained why PBI is a fit pedagogy in teaching technical writing to engineering students. Next, it elaborated components involved in the holistic design of the PBI course, including student sample, timeline, designed sections and units, and designing rationale and principles. This paper then reported the teaching …


Distance,Time And Terms In First Story Detection, Fei Wang Jan 2019

Distance,Time And Terms In First Story Detection, Fei Wang

Doctoral

First Story Detection (FSD) is an important application of online novelty detection within Natural Language Processing (NLP). Given a stream of documents, or stories, about news events in a chronological order, the goal of FSD is to identify the very first story for each event. While a variety of NLP techniques have been applied to the task, FSD remains challenging because it is still not clear what is the most crucial factor in defining the “story novelty”. Giventhesechallenges,thethesisaddressedinthisdissertationisthat the notion of novelty in FSD is multi-dimensional. To address this, the work presented has adopted a three dimensional analysis of the …


Music Information Retrieval For Irish Traditional Music Automatic Analysis Of Harmonic, Rhythmic, And Melodic Features For Efficient Key-Invariant Tune Recognition, Pierre Beauguitte Jan 2019

Music Information Retrieval For Irish Traditional Music Automatic Analysis Of Harmonic, Rhythmic, And Melodic Features For Efficient Key-Invariant Tune Recognition, Pierre Beauguitte

Doctoral

Music making and listening practices increasingly rely on techno logy,and,asaconsequence,techniquesdevelopedinmusicinformation retrieval (MIR) research are more readily available to end users, in par ticular via online tools and smartphone apps. However, the majority of MIRresearchfocusesonWesternpopandclassicalmusic,andthusdoes not address specificities of other musical idioms. Irishtraditionalmusic(ITM)ispopularacrosstheglobe,withregular sessionsorganisedonallcontinents. ITMisadistinctivemusicalidiom, particularly in terms of heterophony and modality, and these character istics can constitute challenges for existing MIR algorithms. The bene fitsofdevelopingMIRmethodsspecificallytailoredtoITMisevidenced by Tunepal, a query-by-playing tool that has become popular among ITM practitioners since its release in 2009. As of today, Tunepal is the state of the art for tune recognition in ITM. The research in …


Modeling Impact Of Glass Weave On Differential Phase Skew By Design Of Experiments Method, Feng Zhang Jan 2019

Modeling Impact Of Glass Weave On Differential Phase Skew By Design Of Experiments Method, Feng Zhang

Masters Theses

"The glass weave structure of a manufactured Printed Circuit Board (PCB) is scanned under a Scanning Electron Microscope (SEM), with top-down and cross-sectional views. Previously, analytical methods were used to investigate the glass-weave effect on transition properties in a PCB. Based on the SEM observation, this study was conducted to build full-wave models using various glass-weave types and different relative positions between differential traces and glass-weave bundles. This study aims to obtain the relationship between the glass weave and trace geometry, and the phase skew of the differential trace by using Design of Experiment (DoE) method and simulation results"--Abstract, page …


Electron Transport In One And Two Dimensional Materials, Samuel William Lagasse Jan 2019

Electron Transport In One And Two Dimensional Materials, Samuel William Lagasse

Legacy Theses & Dissertations (2009 - 2024)

This dissertation presents theoretical and experimental studies in carbon nanotubes (CNTs), graphene, and van der Waals heterostructures. The first half of the dissertation focuses on cutting edge tight-binding-based quantum transport models which are used to study proton irradiation-induced single-event effects in carbon nanotubes [1], total ionizing dose effects in graphene [2], quantum hall effect in graded graphene p-n junctions [3], and ballistic electron focusing in graphene p-n junctions [4]. In each study, tight-binding models are developed, with heavy emphasis on tying to experimental data. Once benchmarked against experiment, properties of each system which are difficult to access in the laboratory, …


Efficient Detection Of Diseases By Feature Engineering Approach From Chest Radiograph, Avishek Mukherjee Jan 2019

Efficient Detection Of Diseases By Feature Engineering Approach From Chest Radiograph, Avishek Mukherjee

Legacy Theses & Dissertations (2009 - 2024)

Deep Learning is the new state-of-the-art technology in Image Processing. We applied Deep Learning techniques for identification of diseases from Radiographs made publicly available by NIH. We applied some Feature Engineering approach to augment the data from Anterior-Posterior position to Posterior-Anterior position and vice-versa for all the diseases, at the same point we suppressed ‘No Finding’ radiographs which contributed to more than 50% (approximately 60,000) of the dataset to top 1000 images. We also prepared a model by adding a huge amount of noise to the augmented data, which if need be can be deployed at rural locations which lack …


Secondary Electron Interactions In Exposures Of Euv Photoresists, Steven Grzeskowiak Jan 2019

Secondary Electron Interactions In Exposures Of Euv Photoresists, Steven Grzeskowiak

Legacy Theses & Dissertations (2009 - 2024)

The microelectronic industry’s movement toward smaller feature sizes has necessitated a shift to extreme ultraviolet (EUV) lithography to enable cost-effective patterning of sub 20-nm features. However, this shift from 193-nm lithography (6.4 eV) to EUV (13.5 nm, 92 eV) poses significant obstacles, such that photolithography is now operating in an energy range above the electron binding energies of common atomic species in photoresists. This significant energy increase means the chemical reactions happening within operate in the realm of radiation chemistry instead of photochemistry since the observed reactions are due almost entirely to the action of photoelectrons as they dissipate their …


Synthesis Of Cadmium Arsenide Semiconductor Nanoparticles, Superatomic Silver Clusters, And Silver Coordination Polymers, Sarthak Jashubhai Patel Jan 2019

Synthesis Of Cadmium Arsenide Semiconductor Nanoparticles, Superatomic Silver Clusters, And Silver Coordination Polymers, Sarthak Jashubhai Patel

Legacy Theses & Dissertations (2009 - 2024)

Nanomaterials have chemical, electronic, optical, and other properties distinct from their bulk counterparts. However, the atom-precise synthesis of these materials remains a challenge, leaving open many scientific questions regarding the size regime between nanoparticulate (quantum confined) and bulk character. In this work, efforts toward the synthesis of nanoparticulate and atom-precise metal and semimetal materials are described. The synthesis of II-V semiconductor Cd3As2 having a near-zero bandgap is discussed. Analysis by UV-Vis absorption spectroscopy and powder X-ray diffraction indicate the formation of material with unexpected crystallinity and absorption properties The interaction between the molecular source of As and the solvent was …


Investigation Of Optical Second Harmonic Generation From Si (100) With Process Tailored Surface & Embedded Ag Nanostructures For Advanced Si Nonlinear Nanophotonics, Gourav Bhowmik Jan 2019

Investigation Of Optical Second Harmonic Generation From Si (100) With Process Tailored Surface & Embedded Ag Nanostructures For Advanced Si Nonlinear Nanophotonics, Gourav Bhowmik

Legacy Theses & Dissertations (2009 - 2024)

The challenge of current microelectronic architecture in transmission bandwidth and power consumption can be potentially solved by using silicon photonics technologies that are compatible with modern CMOS fabrication. One of the critical active photonic devices for Si photonics is a Si based optical modulator. Most of the reported silicon modulators rely on the free carrier plasma dispersion effect. In those cases, a weak change of the refractive index obtained by carrier accumulation, injection or depletion is utilized in a Mach-Zehnder interferometer or a microring resonator to achieve intensity modulation, rendering them difficult for chip-level implementation due to a large footprint …


Development And Demonstration Of A Processing And Assembly Pathway For A 3d-Synchronous Field Programmable Gate Array, Robert Carroll Jan 2019

Development And Demonstration Of A Processing And Assembly Pathway For A 3d-Synchronous Field Programmable Gate Array, Robert Carroll

Legacy Theses & Dissertations (2009 - 2024)

Field Programmable Gate Arrays (FPGA) are integrated circuits which can implement virtually any digital function and can be configured by a designer after manufacturing. This is beneficial when dedicated application specific runs are not time or cost effective; however, this flexibility comes at the cost of a substantially higher interconnect overhead. Three-dimensional (3D) integration can offer significant improvements in the FPGA architecture by stacking multiple device layers and interconnecting them in the third or vertical dimension, through the substrate, where path lengths are greatly reduced. This will allow for a higher density of devices and improvements in power consumption, signal …


Cvd Molybdenum Disulfide : Material And Device Engineering, Eui Sang Song Jan 2019

Cvd Molybdenum Disulfide : Material And Device Engineering, Eui Sang Song

Legacy Theses & Dissertations (2009 - 2024)

Molybdenum disulfide (MoS2) is a semiconducting 2D layered material that has attracted a lot of attention due to its material properties for electronics and optoelectronics device applications. These include a layer-dependent band gap, an indirect to direct energy transition at monolayer state, and strong light-matter interaction. A large majority of 2D materials and devices have been studied through micromechanical exfoliation for extraction and electron beam lithography for device fabrication. These methodologies while able to generate high quality materials and precisely fabricated devices, are not suitable for large scale production. Efforts have been made to make MoS2 and other 2D materials …


Tetradymite Topological Insulators : Towards High Performance Broadband Photodetection, Asish Parbatani Jan 2019

Tetradymite Topological Insulators : Towards High Performance Broadband Photodetection, Asish Parbatani

Legacy Theses & Dissertations (2009 - 2024)

Topological insulators are characterized by the presence of a finite energy gap in the bulk state and a conducting metallic surface state consisting of odd number of Dirac cones. The conducting surface states are along the edge boundaries, free from disorders and are protected by time reversal symmetry. The presence of Dirac cone leads to universal optical absorption phenomenon like graphene. This phenomenon of universal optical absorption leads to frequency independent photoexcitation of carriers. Bi2Te3, Sb2Te3 and Bi2Se3 belong to tetradymite topological insulators (TTI) family and are often referred to as 3D layered materials. Theoretical predictions characterize TTIs by low …