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Articles 5251 - 5280 of 21795

Full-Text Articles in Engineering

Dynamic Mechanical Properties And Microstructure Of Graphene Oxide Nanosheets Reinforced Cement Composites, Wujian Long, Jingjie Wei, Hongyan Ma, Feng Xing Dec 2017

Dynamic Mechanical Properties And Microstructure Of Graphene Oxide Nanosheets Reinforced Cement Composites, Wujian Long, Jingjie Wei, Hongyan Ma, Feng Xing

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

This paper presents an experimental investigation on the effect of uniformly dispersed graphene oxide (GO) nanosheets on dynamic mechanical properties of cement based composites prepared with recycled fine aggregate (RFA). Three different amounts of GO, 0.05%, 0.10%, and 0.20% in mass of cement, were used in the experiments. The visual inspections of GO nanosheets were also carried out after ultrasonication by transmission electron microscope (TEM) atomic force microscope (AFM), and Raman to characterize the dispersion effect of graphite oxide. Dynamic mechanical analyzer test showed that the maximum increased amount of loss factor and storage modulus, energy absorption was 125%, 53%, …


Effect Of Explosive Charge Geometry On Shockwave Propagation, Catherine E. Johnson, Phillip R. Mulligan, Kelly Williams, Martin Langenderfer, Jeffrey Heniff Dec 2017

Effect Of Explosive Charge Geometry On Shockwave Propagation, Catherine E. Johnson, Phillip R. Mulligan, Kelly Williams, Martin Langenderfer, Jeffrey Heniff

Mining Engineering Faculty Research & Creative Works

With advancements in the 3D printing of explosives, the understanding how the shape of an explosive charge influences the energy expansion and subsequently the focusing of energy is becoming increasingly more important. Theoretically, explosive charges could be printed to focus the energy on targets of interest or to synthesize nanomaterials. The first step to quantifying the energy expansion and shock wave convergences for a 3D printed charge is to examine simple geometries of traditional explosive charges (non-3D printed). Detonation of 15 PETN-based primasheet charges in the spherical, cubic, cylindrical, and tetrahedral configurations have been examined in this study. Qualitative data …


Rheological Properties Considering The Effect Of Aggregates On Concrete Slump Flow, Tae Yong Shin, Jae Hong Kim, Seong Ho Han Dec 2017

Rheological Properties Considering The Effect Of Aggregates On Concrete Slump Flow, Tae Yong Shin, Jae Hong Kim, Seong Ho Han

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

Rheology of concrete allows us to understand the flow behavior of concrete and further extend the quantitative evaluation of its construction performance. The use of a concrete rheometer is promising for the purpose but sometimes limited high associated cost and procedure complexity. This study proposes a simulation-based model that correlates the slump flow test results to a concrete's rheological properties, allowing quantitative evaluation through this simple method. The proposed model is based on single-fluid simulation using the volume-of-fluid method, with an extension to accommodate the partial segregation of coarse aggregates. Either the channel flow or the L-shaped panel filling of …


Crustal Thickness Beneath Libya And The Origin Of Partial Melt Beneath As Sawda Volcanic Province From Receiver Function Constraints, Awad A. Lemnifi, Abdelsalam Elshaafi, John Browning, Nassib Aouad, Saad K. El Ebaidi, Kelly K. Liu, Agust Gudmundsson Dec 2017

Crustal Thickness Beneath Libya And The Origin Of Partial Melt Beneath As Sawda Volcanic Province From Receiver Function Constraints, Awad A. Lemnifi, Abdelsalam Elshaafi, John Browning, Nassib Aouad, Saad K. El Ebaidi, Kelly K. Liu, Agust Gudmundsson

Mining Engineering Faculty Research & Creative Works

This study investigates crustal thickness and properties within the Libyan region. Results obtained from 15 seismic stations belonging to the Libyan Center for Remote Sensing and Space Science are reported, in addition to 3 seismic stations publically available, using receiver functions. The results show crustal thicknesses ranging from 24 km to 36 km (with uncertainties ranging between ±0.10 km and ±0.90 km). More specifically, crustal thickness ranges from 32 km to 36 km in the southern portion of the Libyan territory then becomes thinner, between 24 km and 30 km, in the coastal areas of Libya and thinnest, between 24 …


Performance Metrics For Frequency Selective Surface-Based Sensors, Mahboobeh Mahmoodi, Kristen M. Donnell Dec 2017

Performance Metrics For Frequency Selective Surface-Based Sensors, Mahboobeh Mahmoodi, Kristen M. Donnell

Electrical and Computer Engineering Faculty Research & Creative Works

A frequency selective surface (FSS) is a periodic array of conductive elements (located on a dielectric substrate) that has a specific transmission or reflection response when illuminated with electromagnetic energy. Since the FSS response is sensitive to changes in substrate properties (permittivity, loss tangent, and thickness) as well as element geometry, FSS-based sensors have strong potential as a wireless sensing solution. To this end, this paper proposes three performance metrics (resonant frequency, resonant depth, and quality factor) to quantify the effect of substrate properties on sensor performance. These metrics are applied to a patch- A nd loop-based FSS sensor. The …


An Innovative Fuzzy Backstepping Sliding Mode Controller For A Tri-Rotor Unmanned Aerial Vehicle, Shiqian Wang, Jingjuan Zhang, Qian Zhang, Chaoying Pei Dec 2017

An Innovative Fuzzy Backstepping Sliding Mode Controller For A Tri-Rotor Unmanned Aerial Vehicle, Shiqian Wang, Jingjuan Zhang, Qian Zhang, Chaoying Pei

Mechanical and Aerospace Engineering Faculty Research & Creative Works

The dynamical model of a Tri-Rotor Unmanned Aerial Vehicle (UAV) is presented in this paper. The Tri-Rotor has three rotors with two fixed-pitch propellers and a tiltable propeller to control the yaw displacement. The model is obtained via the Newton–Euler approach and a nonlinear control strategy called fuzzy backstepping sliding mode control is proposed for the attitude stabilization and altitude tracking of the vehicle. The designed controller consists of a backstepping sliding mode controller and a fuzzy logic controller. For the problem of determining the backstepping sliding mode control coefficients, an optimization method of gradient descent algorithm has been used. …


Synthesis Of Regioselectively Acylated Quercetin Analogues With Improved Antiplatelet Activity, Yu Duan, Na Sun, Min Xue, Xiaolan Wang, Hu Yang Dec 2017

Synthesis Of Regioselectively Acylated Quercetin Analogues With Improved Antiplatelet Activity, Yu Duan, Na Sun, Min Xue, Xiaolan Wang, Hu Yang

Chemical and Biochemical Engineering Faculty Research & Creative Works

The aim of the present study was to report on a complete synthetic approach, namely benzylation-hydrolysis-acylation-hydrogenation, to the synthesis of regioselectively acylated quercetin analogues using low-cost rutin as a starting material. Three quercetin analogues, quercetin-3-O-propionate (Q-pr), quercetin-3-O-butyrate (Q-bu) and quercetin-3-O-valerate (Q-va), containing 3-, 4- and 5-carbon aliphatic acyl chains, respectively, were synthesized and characterized with 1H nuclear magnetic resonance (NMR), 13C NMR and mass spectrometry. Compared with quercetin, all three analogues exhibited improved lipophilicity. The lipophilicity of the analogue increased with increasing acyl chain length. Q-va exhibited the highest lipophilicity among the three analogues, but a lower water …


Nanograin Size Effects On The Strength Of Biphase Nanolayered Composites, Sixie Huang, Irene J. Beyerlein, Caizhi Zhou Dec 2017

Nanograin Size Effects On The Strength Of Biphase Nanolayered Composites, Sixie Huang, Irene J. Beyerlein, Caizhi Zhou

Materials Science and Engineering Faculty Research & Creative Works

In this work, we employ atomic-scale simulations to uncover the interface-driven deformation mechanisms in biphase nanolayered composites. Two internal boundaries persist in these materials, the interlayer crystalline boundaries and intralayer biphase interfaces, and both have nanoscale dimensions. These internal surfaces are known to control the activation and motion of dislocations, and despite the fact that most of these materials bear both types of interfaces. From our calculations, we find that the first defect event, signifying yield, is controlled by the intralayer spacing (grain size, d), and not the intralayer biphase spacing (layer thickness, h). The interplay of two internal sizes …


An Analysis Of Scattering From Snow With Relaxed Hierachical Equivalent Source Algorithm, Chan Fai Lum, Hong Tat Ewe, Fu Xin, Li (Lijun) Jun Jiang, Hean Teik Chuah Dec 2017

An Analysis Of Scattering From Snow With Relaxed Hierachical Equivalent Source Algorithm, Chan Fai Lum, Hong Tat Ewe, Fu Xin, Li (Lijun) Jun Jiang, Hean Teik Chuah

Electrical and Computer Engineering Faculty Research & Creative Works

Traditionally, Radiative Transfer (RT) formulation has been used to simulate scattering from snow layer with the incorporation of phase matrix of scatterers in the formulation. Typically, spherical scatterers were assumed to represent the ice particles embedded inside the air medium and Mie phase matrix was applied. However, the real scatterers in the actual snow are generally more irregular than the assumed spherical shape. In this paper, a numerical solution based on the Hierarchical Equivalent Source Algorithm (HESA) has been developed to calculate the phase matrix of scatterers of other shapes to be incorporated in the existing RT formulation. Results from …


4h-Sic Electrostatic Microactuator With Optically Controlled Actuation, Feng Zhao, Marcus Daniel Trimble Dec 2017

4h-Sic Electrostatic Microactuator With Optically Controlled Actuation, Feng Zhao, Marcus Daniel Trimble

Electrical and Computer Engineering Faculty Research & Creative Works

This paper presents that actuation of a 4H-SiC electrostatic micro actuator was controlled by an optical signal. The micro actuator was monolithically integrated with a transistor switch on the 4H-SiC substrate. DC voltage bias on the transistor produced an electrostatic force on the micro actuator, which bended down the cantilever beam and caused a shift in the resonant frequency to a lower value. The transistor switched on when activated by UV illumination, and photogenerated current in the transistor reduced bias voltage on the micro actuator, which relaxed the electrostatic force and consequently increased the resonant frequency.


How We Compute N Matters To Estimates Of Mixing In Stratified Flows, Robert S. Arthur, Subhas K. Venayagamoorthy, Jeffrey R. Koseff, Oliver B. Fringer Nov 2017

How We Compute N Matters To Estimates Of Mixing In Stratified Flows, Robert S. Arthur, Subhas K. Venayagamoorthy, Jeffrey R. Koseff, Oliver B. Fringer

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

Most commonly used models for turbulent mixing in the ocean rely on a background stratification against which turbulence must work to stir the fluid. While this background stratification is typically well defined in idealized numerical models, it is more difficult to capture in observations. Here, a potential discrepancy in ocean mixing estimates due to the chosen calculation of the background stratification is explored using direct numerical simulation data of breaking internal waves on slopes. Two different methods for computing the buoyancy frequency, one based on a three-dimensionally sorted density field (often used in numerical models) and the other based on …


On The Propagation Of Gravity Currents Over And Through A Submerged Array Of Circular Cylinders, Jian Zhou, Claudia Cenedese, Tim Williams, Megan Ball, Subhas K. Venayagamoorthy, Roger I. Nokes Nov 2017

On The Propagation Of Gravity Currents Over And Through A Submerged Array Of Circular Cylinders, Jian Zhou, Claudia Cenedese, Tim Williams, Megan Ball, Subhas K. Venayagamoorthy, Roger I. Nokes

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

The propagation of full-depth lock-exchange bottom gravity currents past a submerged array of circular cylinders is investigated using laboratory experiments and large eddy simulations. Firstly, to investigate the front velocity of gravity currents across the whole range of array density (i.e. the volume fraction of solids), the array is densified from a flatbed towards a solid slab under a particular submergence ratio, where is the flow depth and is the array height. The time-averaged front velocity in the slumping phase of the gravity current is found to first decrease and then increase with increasing. Next, a new geometrical framework consisting …


Nonlinear Optical Properties Of Gesbs Chalcogenide Waveguides, Ju Won Choi, Byoung Uk Sohn, George F.R. Chen, Dawn T.H. Tan, Zhaohong Han, Lionel C. Kimerling, Charmayne Smith (Lonergan), Kathleen A. Richardson, Anuradha M. Agarwal Nov 2017

Nonlinear Optical Properties Of Gesbs Chalcogenide Waveguides, Ju Won Choi, Byoung Uk Sohn, George F.R. Chen, Dawn T.H. Tan, Zhaohong Han, Lionel C. Kimerling, Charmayne Smith (Lonergan), Kathleen A. Richardson, Anuradha M. Agarwal

Materials Science and Engineering Faculty Research & Creative Works

We characterize the nonlinear optical properties of GeSbS chalcogenide glasses with fiber-based experiments. A waveguide nonlinear parameter of 7 W-1/m and nonlinear refractive index of 3.71 x 10-18 m2/W are estimated by self-phase modulation. A GeSbS waveguide could also generate a supercontinuum from 1280 to 2120 nm at the -30 dB level for maximum coupled power of 340 W, showing a 14-fold spectral broadening of the input spectrum explained by cascaded stimulated Raman scattering.


Effective Mechanical Properties Of Multilayer Nano-Heterostructures, T Mukhopadhyay, A Mahata, S Adhikari, Mohsen Asle Zaeem Nov 2017

Effective Mechanical Properties Of Multilayer Nano-Heterostructures, T Mukhopadhyay, A Mahata, S Adhikari, Mohsen Asle Zaeem

Materials Science and Engineering Faculty Research & Creative Works

Two-dimensional and quasi-two-dimensional materials are important nanostructures because of their exciting electronic, optical, thermal, chemical and mechanical properties. However, a single-layer nanomaterial may not possess a particular property adequately, or multiple desired properties simultaneously. Recently a new trend has emerged to develop nano-heterostructures by assembling multiple monolayers of different nanostructures to achieve various tunable desired properties simultaneously. For example, transition metal dichalcogenides such as MoS2 show promising electronic and piezoelectric properties, but their low mechanical strength is a constraint for practical applications. This barrier can be mitigated by considering graphene-MoS2 heterostructure, as graphene possesses strong mechanical properties. We …


Experimental Measurement Of Residual Stress And Distortion In Additively Manufactured Stainless Steel Components With Various Dimensions, M. Ghasri-Khouzani, H. Peng, R. Rogge, R. Attardo, P. Ostiguy, J. Neidig, R. Billo, D. Hoelzle, M. R. Shankar Nov 2017

Experimental Measurement Of Residual Stress And Distortion In Additively Manufactured Stainless Steel Components With Various Dimensions, M. Ghasri-Khouzani, H. Peng, R. Rogge, R. Attardo, P. Ostiguy, J. Neidig, R. Billo, D. Hoelzle, M. R. Shankar

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Disk-shaped 316L stainless steel parts with various diameters and heights were additively manufactured using a direct metal laser sintering (DMLS) technique. Neutron diffraction was used to profile the residual stresses in the samples before and after removal of the build plate and support structures. Moreover, distortion level of the parts before and after the removal was quantified using a coordinate measuring machine (CMM). Large tensile in-plane stresses (up to ≈ 400 MPa) were measured near the as-built disk top surfaces, where the stress magnitude decreased from the disk center to the edges. The stress gradient was steeper for the disks …


A Modeling Enterprise For Chemistry Of Indoor Environments (Cie), G. C. Morrison, N. Carslaw, M. S. Waring Nov 2017

A Modeling Enterprise For Chemistry Of Indoor Environments (Cie), G. C. Morrison, N. Carslaw, M. S. Waring

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

No abstract provided.


Time-Dependent Prestress Loss Behavior Of Girders In Missouri Bridge A7957 Compared With A U.S. Data Set Of High-Performance Concrete Bridge Girders, Hayder H. Alghazali, John J. Myers Nov 2017

Time-Dependent Prestress Loss Behavior Of Girders In Missouri Bridge A7957 Compared With A U.S. Data Set Of High-Performance Concrete Bridge Girders, Hayder H. Alghazali, John J. Myers

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

In this study, six precast, prestressed concrete girders were constructed and instrumented to measure prestress losses of bridge A7957 in Missouri. The concrete mixture for the bridge was designed with varying mechanical and rheological properties. High-strength concrete, high-strength self-consolidating concrete, and normal-strength self-consolidating concrete were used to construct the bridge girders. Vibrating wire strain gauges with integrated thermistors were embedded through the girders' cross sections to measure strains and temperatures. The measured short- and long-term prestress losses were compared with those obtained using different empirical models, specified in the AASHTO LRFD Bridge Design Specifications and in the PCI Design Handbook: …


Time Effect Of Water Injection On The Mechanical Properties Of Coal And Its Application In Rockburst Prevention In Mining, Xiaofei Liu, Guang Xu, Chong Zhang, Biao Kong, Jifa Qian, Dong Zhu, Mingyao Wei Nov 2017

Time Effect Of Water Injection On The Mechanical Properties Of Coal And Its Application In Rockburst Prevention In Mining, Xiaofei Liu, Guang Xu, Chong Zhang, Biao Kong, Jifa Qian, Dong Zhu, Mingyao Wei

Mining Engineering Faculty Research & Creative Works

Coal seam water injection is widely used to prevent rockbursts in coal mines, and the duration of water injection is an important parameter related to the effectiveness of rockburst prevention, making it of practical importance to optimize the effective water injection duration. This paper presents the test results of the mechanical properties and pore structure of samples with different soaking time, obtained from a working face where rockburst occurred. Soaking time changes the mechanical properties of samples, and this time effect differs with the coal size (from centimeter to nanometer size). Results of numerical simulation and on-site tests in the …


Hollow-Core Frp-Concrete-Steel Bridge Columns Under Torsional Loading, Sujith Anumolu, Omar I. Abdelkarim, Mohanad M. Abdulazeez, Ahmed Gheni, Mohamed Elgawady Nov 2017

Hollow-Core Frp-Concrete-Steel Bridge Columns Under Torsional Loading, Sujith Anumolu, Omar I. Abdelkarim, Mohanad M. Abdulazeez, Ahmed Gheni, Mohamed Elgawady

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

This paper presents the behavior of hollow-core fiber-reinforced polymer-concrete-steel (HC-FCS) columns under cyclic torsional loading combined with constant axial load. The HC-FCS consists of an outer fiber-reinforced polymer (FRP) tube and an inner steel tube, with a concrete shell sandwiched between the two tubes. The FRP tube was stopped at the surface of the footing, and provided confinement to the concrete shell from the outer direction. The steel tube was embedded into the footing to a length of 1.8 times the diameter of the steel tube. The longitudinal and transversal reinforcements of the column were provided by the steel tube …


Learning Curve Analysis Using Intensive Longitudinal And Cluster-Correlated Data, Xiao Zhong, Zeyi Sun, Haoyi Xiong, Neil Heffernan, Md Monirul Islam Nov 2017

Learning Curve Analysis Using Intensive Longitudinal And Cluster-Correlated Data, Xiao Zhong, Zeyi Sun, Haoyi Xiong, Neil Heffernan, Md Monirul Islam

Engineering Management and Systems Engineering Faculty Research & Creative Works

Intensive longitudinal and cluster-correlated data (ILCCD) can be generated in any situation where numerical or categorical characteristics of multiple individuals or study units are observed and measured at tens, hundreds, or thousands of occasions. The spacing of measurements in time for each individual can be regular or irregular, fixed or random, and the number of characteristics measured at each occasion may be few or many. Such data can also arise in situations involving continuous-time measurements of recurrent events. Generalized linear models (GLMs) are usually considered for the analysis of correlated non-normal data, while multivariate analysis of variance (MANOVA) is another …


On Linear Precoding Of Nonregenerative Mimo Relay Networks For Finite-Alphabet Source, Xiao Liang, Zhi Ding, Chengshan Xiao Nov 2017

On Linear Precoding Of Nonregenerative Mimo Relay Networks For Finite-Alphabet Source, Xiao Liang, Zhi Ding, Chengshan Xiao

Electrical and Computer Engineering Faculty Research & Creative Works

Multiple input and multiple output (MIMO) relay could provide broader wireless coverage, better diversity, and higher throughput. Most existing precoder designs for either source or relay node are based on the assumption of Gaussian input signals. However, recent works have revealed possible performance loss of MIMO systems originally optimized for Gaussian source signals when applied to practical finite-alphabet source signals. In this work, we investigate the design problem of joint MIMO precoding for wireless two-hop nonregenerative cooperative relay networks under finite-alphabet source signals. We identify several structural properties of optimal precoders. Specifically, we provided the optimal left singular vectors of …


Broadband Infrared Absorbers With Stacked Double Chromium Ring Resonators, H. Deng, L. Stan, D. Czaplewski, Jie Gao, Xiaodong Yang Nov 2017

Broadband Infrared Absorbers With Stacked Double Chromium Ring Resonators, H. Deng, L. Stan, D. Czaplewski, Jie Gao, Xiaodong Yang

Mechanical and Aerospace Engineering Faculty Research & Creative Works

No abstract provided.


Spectroscopic Ellipsometry Studies On Zncdo Thin Films With Different Cd Concentrations Grown By Pulsed Laser Deposition, Shuai Chen, Qingxuan Li, Ian Ferguson, Tao Lin, Lingyu Wan, Zhe Chuan Feng, Liping Zhu, Zhizhen Ye Nov 2017

Spectroscopic Ellipsometry Studies On Zncdo Thin Films With Different Cd Concentrations Grown By Pulsed Laser Deposition, Shuai Chen, Qingxuan Li, Ian Ferguson, Tao Lin, Lingyu Wan, Zhe Chuan Feng, Liping Zhu, Zhizhen Ye

Electrical and Computer Engineering Faculty Research & Creative Works

A set of Zn 1-x Cd x O thin films with different Cd concentrations was deposited on quartz substrates by Pulsed Laser Deposition (PLD). The properties of these films were investigated by variable angle and temperature dependent spectroscopic ellipsometry (SE). The experimental Zn 1-x Cd x O thin films showed a red shift in the absorption edge with increasing Cd contents at room temperature. For ZnCdO films with the similar Cd concentration, it has been found that the film thickness has important effects on the optical constants (n, k). The variations of optical constants (n, k) and the band gap, …


Modeling And Simulation Of Microgrid, Ahmad Alzahrani, Mehdi Ferdowsi, Pourya Shamsi, Cihan H. Dagli Nov 2017

Modeling And Simulation Of Microgrid, Ahmad Alzahrani, Mehdi Ferdowsi, Pourya Shamsi, Cihan H. Dagli

Electrical and Computer Engineering Faculty Research & Creative Works

Complex computer systems and electric power grids share many properties of how they behave and how they are structured. A microgrid is a smaller electric grid that contains several homes, energy storage units, and distributed generators. The main idea behind microgrids is the ability to work even if the main grid is not supplying power. That is, the energy storage unit and distributed generation will supply power in that case, and if there is excess in power production from renewable energy sources, it will go to the energy storage unit. Therefore, the electric grid becomes decentralized in terms of control …


Solar Irradiance Forecasting Using Deep Neural Networks, Ahmad Alzahrani, Pourya Shamsi, Cihan H. Dagli, Mehdi Ferdowsi Nov 2017

Solar Irradiance Forecasting Using Deep Neural Networks, Ahmad Alzahrani, Pourya Shamsi, Cihan H. Dagli, Mehdi Ferdowsi

Electrical and Computer Engineering Faculty Research & Creative Works

Predicting solar irradiance has been an important topic in renewable energy generation. Prediction improves the planning and operation of photovoltaic systems and yields many economic advantages for electric utilities. The irradiance can be predicted using statistical methods such as artificial neural networks (ANN), support vector machines (SVM), or autoregressive moving average (ARMA). However, they either lack accuracy because they cannot capture long-term dependency or cannot be used with big data because of the scalability. This paper presents a method to predict the solar irradiance using deep neural networks. Deep recurrent neural networks (DRNNs) add complexity to the model without specifying …


Chaotic Behavior In High-Gain Interleaved Dc-Dc Converters, Ahmad Alzahrani, Pourya Shamsi, Mehdi Ferdowsi, Cihan H. Dagli Nov 2017

Chaotic Behavior In High-Gain Interleaved Dc-Dc Converters, Ahmad Alzahrani, Pourya Shamsi, Mehdi Ferdowsi, Cihan H. Dagli

Electrical and Computer Engineering Faculty Research & Creative Works

In this paper, chaotic behavior in high gain dc-dc converters with current mode control is explored. The dc-dc converters exhibit some chaotic behavior because they contain switches. Moreover, in power electronics (circuits with more passive elements), the dynamics become rich in nonlinearity and become difficult to capture with linear analytical models. Therefore, studying modeling approaches and analysis methods is required. Most of the high-gain dc-dc boost converters cannot be controlled with only voltage mode control due to the presence of right half plane zero that narrows down the stability region. Therefore, the need of current mode control is necessary to …


Secure Degrees Of Freedom For The Mimo Wire-Tap Channel With A Multi-Antenna Cooperative Jammer, Mohamed Nafea, Aylin Yener Nov 2017

Secure Degrees Of Freedom For The Mimo Wire-Tap Channel With A Multi-Antenna Cooperative Jammer, Mohamed Nafea, Aylin Yener

Electrical and Computer Engineering Faculty Research & Creative Works

In this paper, a multiple antenna wire-tap channel in the presence of a multi-antenna cooperative jammer is studied. In particular, the secure degrees of freedom (s.d.o.f.) of this channel is established, with $N-{t}$ antennas at the transmitter, $N-{r}$ antennas at the legitimate receiver, and $N-{e}$ antennas at the eavesdropper, for all possible values of the number of antennas, $N-{c}$, at the cooperative jammer. In establishing the result, several different ranges of $N-{c}$ need to be considered separately. The lower and upper bounds for these ranges of $N-{c}$ are derived and are shown to be tight. The achievability techniques developed rely …


An Optical Interferometric Triaxial Displacement Sensor For Structural Health Monitoring: Characterization Of Sliding And Debonding For A Delamination Process, Chen Zhu, Yizheng Chen, Yiyang Zhuang, Yang Du, Rex E. Gerald Ii, Yan Tang, Jie Huang Nov 2017

An Optical Interferometric Triaxial Displacement Sensor For Structural Health Monitoring: Characterization Of Sliding And Debonding For A Delamination Process, Chen Zhu, Yizheng Chen, Yiyang Zhuang, Yang Du, Rex E. Gerald Ii, Yan Tang, Jie Huang

Electrical and Computer Engineering Faculty Research & Creative Works

This paper presents an extrinsic Fabry-Perot interferometer-based optical fiber sensor (EFPI) for measuring three-dimensional (3D) displacements, including interfacial sliding and debonding during delamination. The idea employs three spatially arranged EFPIs as the sensing elements. In our sensor, the three EFPIs are formed by three endfaces of three optical fibers and their corresponding inclined mirrors. Two coincident roof-like metallic structures are used to support the three fibers and the three mirrors, respectively. Our sensor was calibrated and then used to monitor interfacial sliding and debonding between a long square brick of mortar and its support structure (i.e., a steel base plate) …


An Embeddable Optical Strain Gauge Based On A Buckled Beam, Yang Du, Yizheng Chen, Chen Zhu, Yiyang Zhuang, Jie Huang Nov 2017

An Embeddable Optical Strain Gauge Based On A Buckled Beam, Yang Du, Yizheng Chen, Chen Zhu, Yiyang Zhuang, Jie Huang

Electrical and Computer Engineering Faculty Research & Creative Works

We report, for the first time, a low cost, compact, and novel mechanically designed extrinsic Fabry-Perot interferometer (EFPI)-based optical fiber sensor with a strain amplification mechanism for strain measurement. The fundamental design principle includes a buckled beam with a coated gold layer, mounted on two grips. A Fabry-Perot cavity is produced between the buckled beam and the endface of a single mode fiber (SMF). A ceramic ferrule is applied for supporting and orienting the SMF. The principal sensor elements are packaged and protected by two designed metal shells. The midpoint of the buckled beam will experience a deflection vertically when …


Energy-Efficient Fpga-Based Parallel Quasi-Stochastic Computing, Ramu Seva, Prashanthi Metku, Minsu Choi Nov 2017

Energy-Efficient Fpga-Based Parallel Quasi-Stochastic Computing, Ramu Seva, Prashanthi Metku, Minsu Choi

Electrical and Computer Engineering Faculty Research & Creative Works

The high performance of FPGA (Field Programmable Gate Array) in image processing applications is justified by its flexible reconfigurability, its inherent parallel nature and the availability of a large amount of internal memories. Lately, the Stochastic Computing (SC) paradigm has been found to be significantly advantageous in certain application domains including image processing because of its lower hardware complexity and power consumption. However, its viability is deemed to be limited due to its serial bitstream processing and excessive run-time requirement for convergence. To address these issues, a novel approach is proposed in this work where an energy-efficient implementation of SC …