Computer Engineering Commons^™

Broadband Plasmonic-Enhanced Forward And Backward Multiplex Coherent Anti-Stokes Raman Scattering Microscopy, Baoshan Guo, Lan Jiang, Yanhong Hua, Xin Li, Tianhong Cui, Yongfeng Lu

Department of Electrical and Computer Engineering: Faculty Publications

Coherent anti-Stokes Raman scattering (CARS) microscopy is an attractive technique for label-free biochemical-specific characterization of biological specimens. However, it has very low sensitivity in monitoring and imaging molecules present in extremely low concentrations or at fast speeds. To improve this sensitivity, especially for multiplex CARS, the intensity of the pump beam and broadband Stokes beam should be enhanced simultaneously. Therefore, the gold shell particle and gold surface are demonstrated to enhance the forward and backward CARS, respectively. Results show that a signal enhancement factor of ∼25;000 can be achieved for the gold surface and an even higher enhancement factor can …

The Subject Librarian Newsletter, Engineering And Computer Science, Spring 2018, Buenaventura "Ven" Basco

Libraries' Newsletters

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Foreword: Special Section On Electrical Contacts, Ronald A. Coutu Jr., Ravi Mahajan

Electrical and Computer Engineering Faculty Research and Publications

Welcome to the Special Topics Section dedicated to the 2016 Holm Conference on Electrical Contacts. This Special Section contains six high-quality papers that comprehensively describe the state of the art and potential future directions for topics of great interest to our readers. The Editor-in-Chief (EIC), in consultation with the other EICs, Associate Editors (AEs), and domain experts, selects the topics for the Special Sections, and a Guest Editor or AE (GE/AE), who is a leading expert in the technical area, and then directs the solicitation and peer review of the papers. In cases where the GE/AE is also an author, …

Qtsac: An Energy-Efficient Mac Protocol For Delay Minimization In Wireless Sensor Networks, Yuxin Liu, Kaoru Ota, Kuan Zhang, Ming Ma, Naixue Xiong, Anfeng Liu, Jun Long

Department of Electrical and Computer Engineering: Faculty Publications

Millions of sensors are deployed to monitor the smart grid. They consume huge amounts of energy in the communication infrastructure. Therefore, the establishment of an energy-efficient medium access control (MAC) protocol for sensor nodes is challenging and urgently needed. The Quorum-based MAC protocol independently and adaptively schedules nodes’ wake-up times and decreases idle listening and collisions, thereby increasing the network throughput and extending the network lifetime. A novel Quorum time slot adaptive condensing (QTSAC)-based MAC protocol is proposed for achieving delay minimization and energy efficiency for the wireless sensor networks (WSNs). Compared to previous protocols, the QTSAC-based MAC protocol has …

Electron Effective Mass In In0.33ga0.67n Determined By Mid- Infrared Optical Hall Effect, Nerijus Armakavicius, Vallery Stanishev, Sean Knight, Mathias Schubert, Vanya Darakchieva

Department of Electrical and Computer Engineering: Faculty Publications

Mid-infrared optical Hall effect measurements are used to determine the free charge carrier parameters of an unintentionally doped wurtzite-structure c-plane oriented In_0.33Ga_0.67N epitaxial layer. Room temperature electron effective mass parameters of m_ ¼ ð0:20560:013Þm0 andm_k ¼ ð0:20460:016Þm0 for polarization perpendicular and parallel to the c-axis, respectively,were determined. The free electron concentration was obtained as (1.760.2)_1019 cm^-3. Within our uncertainty limits, we detect no anisotropy for the electron effective mass parameter and we estimate the upper limit of the possible effective mass anisotropy as 7%. We discuss the influence of conduction band nonparabolicity on …

H.264 Video Decoder Implemented On Fpgas Using 3×3 And 2×2 Networks-On-Chip, Ian Barge, Cristinel Ababei

Electrical and Computer Engineering Faculty Research and Publications

In this paper, we present the design and verification of the H.264 video decoder algorithm on FPGAs. The primary difference compared to previously reported designs is that the communication between the decoder modules is done via a network-on-chip in our case. The proposed design is a complete system level hardware design described in VHDL and Verilog. We report experimental results for two different implementations. The first implementation uses a 3×3 network-on-chip and is validated on the DE4 development board, which uses Altera's Stratix IV GX FPGA chip. The second implementation uses a 2×2 network-on-chip and is validated on the Cyclone …

Condensation And Subsequent Freezing Delays As A Result Of Using Femtosecond Laser Functionalized Surfaces, Chongji Huang, Ryan Bell, Alfred Tsubaki, Craig Zuhlke, Dennis Alexander

Department of Electrical and Computer Engineering: Faculty Publications

In this paper, the authors report on the use of femtosecond laser surface processing (FLSP) to enhance the anti-icing properties of a commonly used aircraft alloy, Al 7075-O Clad. By changing the surface morphology through FLSP and the surface chemistry through siloxane vapor deposition, the wettability of Al 7075-O Clad was altered. Tall mound and short mound FLSP functionalized surfaces were created through two sets of laser parameters. Condensation and the subsequent freezing of condensates on FLSP Al 7075-O Clad was studied. Both structure height and surface wettability were shown to play a role in the delay of freezing. Freezing …

Collaborative Appearance-Based Place Recognition And Improving Place Recognition Using Detection Of Dynamic Objects, Juan Pablo Munoz

Dissertations, Theses, and Capstone Projects

This dissertation makes contributions to the problem of Long-Term Appearance-Based Place Recognition. We present a framework for place recognition in a collaborative scheme and a method to reduce the impact of dynamic objects on place representations. We demonstrate our findings using a state-of-the-art place recognition approach.

We begin in Part I by describing the general problem of place recognition and its importance in applications where accurate localization is crucial. We discuss feature detection and description and also explain the functioning of several place recognition frameworks.

In Part II, we present a novel framework for collaboration between agents from a pure …

Internet Of Underground Things: Sensing And Communications On The Field For Precision Agriculture, Mehmet C. Vuran, Abdul Salam, Rigoberto Wong, Suat Irmak

School of Computing: Conference and Workshop Papers

The projected increases in World population and need for food have recently motivated adoption of information technology solutions in crop fields within precision agriculture approaches. Internet of underground things (IOUT), which consists of sensors and communication devices, partly or completely buried underground for real-time soil sensing and monitoring, emerge from this need. This new paradigm facilitates seamless integration of underground sensors, machinery, and irrigation systems with the complex social network of growers, agronomists, crop consultants, and advisors. In this paper, state-of-the-art communication architectures are reviewed, and underlying sensing technology and communication mechanisms for IOUT are presented. Recent advances in the …

Electronically Tuned Phase Transition In Germanium Telluride (Gete) Cells For Memory And Rf Switch Applications, Dushyant Tomer, Ronald A. Coutu Jr.

Electrical and Computer Engineering Faculty Research and Publications

Germanium telluride (GeTe) is a phase change material that undergoes an amorphous to crystalline transition upon heating to ~ 200oC. This transition is reversible in nature and results in ~ six orders of magnitude difference in GeTe resistivity which makes it a suitable candidate for data storage and other functional devices. In this work, micro-size phase change test cells were fabricated by RF sputtering GeTe thin films onto silicon (Si) wafers and Si wafers coated with silicon dioxide (SiO2), silicon nitride (Si3N4), and alumina (Al2O3) films. Two different heating methods, conductive and electrical (i.e. Joule heating), were applied to induce …

Analytical Formulas For Mean Gain And Excess Noise Factor In Inas Avalanche Photodiodes, Erum Jamil, Majeed M. Hayat, Gordon A. Keeler

Electrical and Computer Engineering Faculty Research and Publications

It has been known that McIntyre's local multiplication theory for avalanche photodiodes (APDs) does not fully explain the experimental results for single-carrier InAs APDs, which exhibit excess noise factor values below 2. While it has been established that the inclusion of the dead-space effect in the nonlocal multiplication theory resolves this discrepancy, no closed-form formulas for the mean gain and excess noise factor have been specialized to InAs APDs in a nonlocal setting. Upon utilizing prior analytical formulation of single-carrier avalanche multiplication based on age-dependent branching theory in conjunction with nonlocal ionization coefficients and thresholds for InAs, closed-form solutions of …

Employing A User-Centered Design Process For Cybersecurity Awareness In The Power Grid, Jean C. Scholtz, Lyndsey Franklin, Aditya Ashok, Katya Leblanc, Christopher Bonebrake, Eric Andersen, Michael Cassiadoro

Journal of Human Performance in Extreme Environments

In this paper, we discuss the process we are using in the design and implementation of a tool to improve the situation awareness of cyberattacks in the power grid. We provide details of the steps we have taken to date and describe the steps that still need to be accomplished. The focus of this work is to provide situation awareness of the power grid to staff from different, non-overlapping roles in an electrical transmission organization in order to facilitate an understanding of a possible occurrence of a cyberattack. Our approach follows a user-centered design process and includes determining the types …

Silicon Compilation And Test For Dataflow Implementations In Gasp And Click, Swetha Mettala Gilla

Dissertations and Theses

Many modern computer systems are distributed over space. Well-known examples are the Internet of Things and IBM's TrueNorth for deep learning applications. At the Asynchronous Research Center (ARC) at Portland State University we build distributed hardware systems using self-timed computation and delay-insensitive communication. Where appropriate, self-timed hardware operations can reduce average and peak power, energy, latency, and electromagnetic interference. Alternatively, self-timed operations can increase throughput, tolerance to delay variations, scalability, and manufacturability.

The design of complex hardware systems requires design automation and support for test, debug, and product characterization.

This thesis focuses on design compilation and test support for dataflow …

A Fast And Robust Extrinsic Calibration For Rgb-D Camera Networks, Po-Chang Su, Ju Shen, Wanxin Xu, Sen-Ching S. Cheung, Ying Luo

Electrical and Computer Engineering Faculty Publications

From object tracking to 3D reconstruction, RGB-Depth (RGB-D) camera networks play an increasingly important role in many vision and graphics applications. Practical applications often use sparsely-placed cameras to maximize visibility, while using as few cameras as possible to minimize cost. In general, it is challenging to calibrate sparse camera networks due to the lack of shared scene features across different camera views. In this paper, we propose a novel algorithm that can accurately and rapidly calibrate the geometric relationships across an arbitrary number of RGB-D cameras on a network. Our work has a number of novel features. First, to cope …

An Overview Of The Usage Of Default Passwords, Brandon Knierem, Xiaolu Zhang, Philip Levine, Frank Breitinger, Ibrahim Baggili

Electrical & Computer Engineering and Computer Science Faculty Publications

The recent Mirai botnet attack demonstrated the danger of using default passwords and showed it is still a major problem. In this study we investigated several common applications and their password policies. Specifically, we analyzed if these applications: (1) have default passwords or (2) allow the user to set a weak password (i.e., they do not properly enforce a password policy). Our study shows that default passwords are still a significant problem: 61% of applications inspected initially used a default or blank password. When changing the password, 58% allowed a blank password, 35% allowed a weak password of 1 character.

Electron Effective Mass In Sn-Doped Monoclinic Single Crystal B-Gallium Oxide Determined By Mid-Infrared Optical Hall Effect, Sean Knight, Alyssa Mock, Rafal Korlacki, Vanya Darakchieva, Bo Monemar, Yoshinao Kumagai, Ken Goto, Masataka Higashiwaki, Mathias Schubert

Department of Electrical and Computer Engineering: Faculty Publications

The isotropic average conduction band minimum electron effective mass in Sn-doped monoclinic single crystal B-Ga₂O₃ is experimentally determined by the mid-infrared optical Hall effect to be (0.28460.013)m₀ combining investigations on (010) and (_201) surface cuts. This result falls within the broad range of values predicted by theoretical calculations for undoped B-Ga₂O₃. The result is also comparable to recent density functional calculations using the Gaussian-attenuation- Perdew-Burke-Ernzerhof hybrid density functional, which predict an average effective mass of 0.267m₀. Within our uncertainty limits, we detect no anisotropy for the electron effective mass, which …

A Survey Of Digital Systems Curriculum And Pedagogy In Electrical And Computer Engineering Programs, Hector A. Ochoa, Mukul V. Shirvaikar

Faculty Publications

Digital Systems is one of the basic foundational courses in Electrical and Computer Engineering. One of the challenges in designing and modifying the curriculum for the course is the fast pace of technology change in the area. TTL chips that were in vogue with students building physical circuits, have given way to new paradigms like FPGA based synthesis with hardware description languages such as VHDL. However, updating a course is not as simple as just changing the book, and changing the syllabus. A large amount of work needs to be done in terms of selecting the book that will accommodate …

Energy Slices: Benchmarking With Time Slicing, Katarina Grolinger, Hany F. Elyamany, Wilson Higashino, Miriam Am Capretz, Luke Seewald

Electrical and Computer Engineering Publications

Benchmarking makes it possible to identify low-performing buildings, establishes a baseline for measuring performance improvements, enables setting of energy conservation targets, and encourages energy savings by creating a competitive environment. Statistical approaches evaluate building energy efficiency by comparing measured energy consumption to other similar buildings typically using annual measurements. However, it is important to consider different time periods in benchmarking because of differences in their consumption patterns. For example, an office can be efficient during the night, but inefficient during operating hours due to occupants’ wasteful behavior. Moreover, benchmarking studies often use a single regression model for different building categories. …

Uneven-Layered Coding Metamaterial Tile For Ultrawideband Rcs Reduction And Diffuse Scattering, Jianxun Su, Huan He, Zengrui Li, Yaoqing Lamar Yang, Hongcheng Yin, Junhong Wang

Department of Electrical and Computer Engineering: Faculty Publications

In this paper, a novel uneven-layered coding metamaterial tile is proposed for ultra-wideband radar cross section (RCS) reduction and diffuse scattering. The metamaterial tile is composed of two kinds of square ring unit cells with different layer thickness. The reflection phase difference of 180° (±37°) between two unit cells covers an ultra-wide frequency range. Due to the phase cancellation between two unit cells, the metamaterial tile has the scattering pattern of four strong lobes deviating from normal direction. The metamaterial tile and its 90-degree rotation can be encoded as the ‘0’ and ‘1’ elements to cover an object, and diffuse …

Ultraviolet Laser Photolysis Of Hydrocarbons For Nondiamond Carbon Suppression In Chemical Vapor Deposition Of Diamond Films, Li-Sha Fan, Loic Constantin, Da-Wei Li, Lei Liu, Kamran Keramatnejad, Clio Azina, Xi Huang, Hossein Rabiee Golgir, Yao Lu, Zahra Ahmadi, Fei Wang, Jeffrey E. Shield, Bai Cui, Jean-Francois Silvain, Yong-Feng Lu

Department of Electrical and Computer Engineering: Faculty Publications

In this work, we demonstrate that ultraviolet (UV) laser photolysis of hydrocarbon species alters the flame chemistry such that it promotes the diamond growth rate and film quality. Optical emission spectroscopy and laser-induced fluorescence demonstrate that direct UV laser irradiation of a diamond-forming combustion flame produces a large amount of reactive species that play critical roles in diamond growth, thereby leading to enhanced diamond growth. The diamond growth rate is more than doubled, and diamond quality is improved by 4.2%. Investigation of the diamond nucleation process suggests that the diamond nucleation time is significantly shortened and nondiamond carbon accumulation is …

Optimal Computational Power Allocation In Multi-Access Mobile Edge Computing For Blockchain, Yuan Wu, Xiangxu Chen, Jiajun Shi, Kejie Ni, Liping Qian, Liang Huang, Kuan Zhang

Department of Electrical and Computer Engineering: Faculty Publications

Blockchain has emerged as a decentralized and trustable ledger for recording and storing digital transactions. The mining process of Blockchain, however, incurs a heavy computational workload for miners to solve the proof-of-work puzzle (i.e., a series of the hashing computation), which is prohibitive from the perspective of the mobile terminals (MTs). The advanced multi-access mobile edge computing (MEC), which enables the MTs to offload part of the computational workloads (for solving the proof-of-work) to the nearby edge-servers (ESs), provides a promising approach to address this issue. By offloading the computational workloads via multi-access MEC, the MTs can effectively increase their …

Structure-Mediated Excitation Of Air Plasma And Silicon Plasma Expansion In Femtosecond Laser Pulses Ablation, Qingsong Wang, Lan Jiang, Jingya Sun, Changji Pan, Weina Han, Guoyan Wang, Feifei Wang, Kaihu Zhang, Ming Li, Yongfeng Lu

Department of Electrical and Computer Engineering: Faculty Publications

Femtosecond laser-induced surface structures upon multiple pulses irradiation are strongly correlated with the pulse number,which in turn significantly affects successive laser-material interactions. By recording the dynamics of femtosecond laser ablation of silicon using time-resolved shadowgraphy, here we present direct visualization of the excitation of air plasma induced by the reflected laser during the second pulse irradiation.The interaction of the air plasma and silicon plasma is found to enhance the shockwave expansion induced by silicon ablation in the longitudinal direction, showing anisotropic expansion dynamics in different directions. We further demonstrate the vanishing of air plasma as the pulse number increases because …

Deformation Behavior Of Foam Laser Targets Fabricated By Two-Photon Polymerization, Ying Liu, John H. Campbell, Ori Stein, Lijia Jiang, Jared Hund, Yongfeng Lu

Department of Electrical and Computer Engineering: Faculty Publications

Two-photon polymerization (2PP), which is a three-dimensional micro/nano-scale additive manufacturing process, is used to fabricate component for small custom experimental packages (“targets”) to support laser-driven, high-energy-density physics research. Of particular interest is the use of 2PP to deterministically print millimeter-scale, low-density, and low atomic number (CHO) polymer matrices (“foams”). Deformation during development and drying of the foam structures remains a challenge when using certain commercial acrylic photo-resins. Acrylic resins were chosen in order to meet the low atomic number requirement for the foam; that requirement precludes the use of low-shrinkage organic/inorganic hybrid resins. Here, we compare the use of acrylic …

Bias-Dependent Scanning Tunneling Microscopy Signature Of Bridging-Oxygen Vacancies On Rutile Tio2(110), Willie B. Maddox, Danda P. Acharya, G. Jeremy Leong, Peter Sutter, Cristian V. Ciobanu

Department of Electrical and Computer Engineering: Faculty Publications

The rutile TiO₂(110) surface has long-served as a wellcharacterized, prototypical transition-metal oxide surface used in heterogeneous catalysis and photocatalytic water splitting. Naturally occurring defects on this surface, called bridging-oxygen (BO) vacancies, are important as they determine the overall reactivity of the surface. Herein, we report a bias-dependent, scanning tunneling microscopy (STM) signature of the BO vacancies on TiO₂(110): for sample bias voltages past a threshold of +3 V, the bright vacancies are flanked on either side (along the oxygen row) by two dark spots approximately shaped like half-moons. The BO vacancies have a bright aspect below …

Experimental Analyses On Multiscale Structural And Mechanical Properties Of Ε-Si/Gesi/C-Si Materials, Wei Qiu, Lu-Lu Ma, Hong-Tao Wang, Ren-Rong Liang, Yu-Cheng Zhao, Yun-Shen Zhou

Department of Electrical and Computer Engineering: Faculty Publications

Strained silicon (ε-Si) is a promising material that could extend Moore’s law by enhancing electron mobility. A ε-Si material is usually composed of multiscale, multilayer heterostructures, where the strained-silicon film or strap is tens-of-nanometers thick, and its buffer layers are of the micrometer scale. The structural properties determine the electrical performance and reliability of ε-Si-based devices. Inhomogeneous residual stress is induced during the preparation, which induces ε-Si structure failure. In this work, biaxial strained-silicon films that contain graded and relaxed germanium-silicon buffer layers were prepared on monocrystalline silicon wafers through reduced-pressure chemical-vapor epitaxy. The layer components and thicknesses were measured …

Adaptive Transmission Range Based Topology Control Scheme For Fast And Reliable Data Collection, Haojun Teng, Kuan Zhang, Mianxiong Dong, Kaoru Ota, Anfeng Liu, Ming Zhao, Tian Wang

Department of Electrical and Computer Engineering: Faculty Publications

An Adaptive Transmission Range Based Topology Control (ATRTC) scheme is proposed to reduce delay and improve reliability for data collection in delay and loss sensitive wireless sensor network. The core idea of the ATRTC scheme is to extend the transmission range to speed up data collection and improve the reliability of data collection.The main innovations of our work are as follows: (1) an adaptive transmission range adjustment method is proposed to improve data collection reliability and reduce data collection delay. The expansion of the transmission range will allow the data packet to be received by more receivers, thus improving the …

Information Theory And Cognition: A Review, Khalid Sayood

Department of Electrical and Computer Engineering: Faculty Publications

We examine how information theory has been used to study cognition over the last seven decades. After an initial burst of activity in the 1950s, the backlash that followed stopped most work in this area. The last couple of decades has seen both a revival of interest, and a more firmly grounded, experimentally justified use of information theory. We can view cognition as the process of transforming perceptions into information—where we use information in the colloquial sense of the word. This last clarification is one of the problems we run into when trying to use information theoretic principles to understand …

Integrated Vacuum-Ultraviolet, Mid And Near-Ultraviolet, Visible, Near, Mid And Far Infrared And Terahertz Optical Hall Effect (Ohe) Instrument, And Method Of Use, Tino Hofmann, Mathias M. Schubert, Stefan Schoeche, Philipp Kuehne, Craig M. Herzinger, John A. Woollam, Gregory K. Pribil, Thomas E. Tiwald, Sean R. Knight

Department of Electrical and Computer Engineering: Faculty Publications

Optical Hall Effect (OHE) method for evaluating such as free charge carrier effective mass, concentration, mobility and free charge carrier type in a sample utilizing a permanent magnet at room temperature.

Fiber - Optic Temperature And Flow Sensor System And Methods, Ming Han, Guigen Liu, Weilin Hou

Department of Electrical and Computer Engineering: Faculty Publications

A fiber optic sensor, a process for utilizing a fiber optic sensor, and a process for fabricating a fiber optic sensor are described, where a double-side-polished silicon pillar is attached to an optical fiber tip and forms a Fabry-Perot cavity. In an implementation, a fiber optic sensor in accordance with an exemplary embodiment includes an optical fiber configured to be coupled to a light source and a spectrometer; and a single silicon layer or multiple silicon layers disposed on an end face of the optical fiber, where each of the silicon layer(s) defines a Fabry-Perot interferometer, and where the sensor …

Non-Vacuum Preparation Of Wse2 Thin Films Via The Selenization Of Hydrated Tungsten Oxide Prepared Using Chemical Solution Methods, Christopher L. Exstrom, Scott A. Darveau, Megan E. Falconer, Jessica R. Blum, Whitney M. Colling, Natale J. Ianno

Department of Electrical and Computer Engineering: Faculty Publications

It is known that tungsten oxide may be reacted with selenium sources to form WSe₂ but literature reports include processing steps that involve high temperatures, reducing atmospheres, and/or oxidative pre-treatments of tungsten oxide. In this work, we report a non-vacuum process for the fabrication of compositionally high quality WSe₂ thin films via the selenization of tungsten oxide under milder conditions. Tungsten source materials were various hydrated WO₃ and WO_2.9 compounds that were prepared using chemical solution techniques. Resulting films were selenized using a two-stage heating profile (250 °C for 15 minutes and 550 °C for 30 …