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2014 ECE Abstracts

1.0 RobustICA-Based Blind Separation Of Convolutive Mixtures

Authors: Zaid Albataineh; Fathi Salem

Abstract: We present a frequency-domain method based on robust independent component analysis (RICA) to address the multichannel blind source separation (BSS) problem of convolutive speech mixtures in highly reverberant environments. We apply the algorithm to separate the source signals in adverse conditions i.e. highly reverberation conditions and when the short observation signals are available. Furthermore, we study the impact of several parameters on the performance of separation, e.g. overlapping ratio and window type in the frequency-domain method. We also perform the comparison between different techniques to solve the permutation ambiguity. Through Simulations and real-world experiments, we verify the superiority of the presented algorithm over other state-of-the-art BSS algorithms, e.g., recursive regularized ICA (RR-ICA), independent vector analysis (IVA) and others.

 

Constrained Blind Multiuser Detection For DS-CDMA System

Authors: Zaid Albataineh; Fathi Salem

Abstract: A blind multiuser detector is presented to enhance the computational complexity and mitigate the multiple access interference (MAI). This detector is targeting direct-sequence code division multiple access DS-CDMA communication systems. The ill-condition of the covariance matrix of the received signals degrades the performance of the linear minimum mean-squared error LMMSE detector-- especially, when the Signal to noise ratio is high and small data set is available.. In this poster, we introduce a constrained blind multiuser detection approach in order to improve performance with imposing a regularization parameter to tackle the ill-conditioning of the covariance matrix. Through simulation results, we verify that the proposed method improves the performance of the blind multiuser detection and outperforms the conventional multiuser detections.

 

Increasing Efficiency Of Monte Carlo Particle-Fluid Collision Calculations On GPU

Authors: Charles Bardel; John Verboncoeur

Abstract: Monte Carlo particle collision calculations are computationally expensive for particle-in-cell codes. One approach is to calculate the energy of every particle to calculate the probability of a type of collision, then perform those collisions for a small number of particles. An alternative approach is utilizing the null collision method [1], which consists of taking randomly selected sample particles for collision with total collision probability, which is independent of particle energy. The approach described above is then applied to the sample. The null collision method has sparse random access of particles in the particle array which has drawbacks on the GPU threads. The threads work in sets called warps and issues one memory instruction with SIMD architecture. When memory instructions are distant, they are issued as individual instructions, however, when two memory instructions are located within 128 bytes [2] of each other they can be coalesced into one instruction. By utilizing the data structure and algorithm presented in [3], for efficient particle to grid charge accumulation on the GPU, all particles contained within a cell are memory contiguous. This paper examines the effect of selecting contiguous particles for collision through the same list. This setup does not require energy of each particle to be calculated and optimizes the memory-bandwidth in GPU without significant effect on the result of the simulation.

This work was supported in part by AFOSR Grant on the Basic Physics of Distributed Plasma Discharges.

  

Dynamic Modeling Of Robotic Fish Actuated By Pectoral Fins With Flexible Passive Joint

Authors: Sanaz Bazaz Behbahani; Xiaobo Tan

Abstract: Pectoral fins are important actuation mechanisms in achieving maneuvering and propulsion for robotic fish. Existing designs predominantly adopt a rigid joint connecting the actuator to the pectoral fin, which requires differential

actuation speeds in the power and recovery strokes in order to produce thrust and limits the overall actuation frequency.

To address this problem, we propose a novel design of a flexible joint, which enables the pectoral fin to sweep back passively along the fish body in the recovery stroke, to minimize the drag, while maintaining the prescribed motion in the power stroke. The pectoral fin mechanism is modeled by two rigid

segments connected with a pair of torsional spring and damper. This design results in a net thrust even with the same recovery and power stroke speed within each fin beat cycle, which simplifies the fin control. Experimental results on a robotic fish prototype validates the effectiveness of the proposed model, and demonstrates the significant advantage of the proposed fin joint over the rigid joint.

This work was supported in part by This work was supported by National Science Foundation (Grant DBI-0939454, CNS-1059373, IIS-0916720 , IIS-1319602, and CCF-1331852).

 

A Lyapunov Function Based Fast Transient Stability Screening And Ranking Tool

Authors: Mohammed Ben-Idris; Joydeep Mitra

Abstract: As a result of market forces, increased renewable generation, and recent advances in power flow control technologies, power systems are increasingly being operated closer to their stability limits. On-line transient stability assessment, TSA, has become one of the important features for systems that operate in such stressed environment. Attempts to reach on-line transient stability assessment have been facing high computation burden and low calculation speed. Most of the current strategies drop off the non-severe contingencies using screening tools and perform detailed simulations on the severe contingencies. The most important factors of any screening tool are the absolute capture of the unstable events and the efficiency of capturing the stable events.

This work introduces a fast transient stability screening tool to classify a designated set of contingencies into stable and unstable subsets using direct methods. The proposed method is based on the conservativeness of the transient stability direct methods. The classification processes of the contingencies are performed along the solution trajectory towards the Controlling Unstable Equilibrium Point, controlling UEP. The proposed screening tool is intended to reliably capture the unstable contingencies and efficiently reduce the number of contingencies that need further analyses. If a numerical problem is encountered during the computation, the proposed scheme applies homotopy-based approaches to find the desired solution. If the numerical problem cannot be solved using homotopy-based methods, the contingency is sent to a time-domain simulator for further analysis. The method is applied to the Western System Coordinating Council (WSCC) test system and results are presented.

 

Application Of Single Crystal Diamond For Swift-Heavy Ion Beam Detector

Authors: Ayan Bhattacharya; Andreas Stolz; Timothy A. Grotjohn

Abstract: Diamond has some extreme material properties which makes it a very attractive candidate for thermal, optical and nuclear fusion applications. In the last couple of decades, application of diamond for high energy radiation detector has become an emerging field of interest. The nature of interaction of ions with materials depend on the ion’s mass, energy. Diamond has good radiation tolerance for detecting swift heavy ion beam as compared to many other semiconductor materials. In this study, single crystal diamond is investigated as a detector for swift heavy ion beams. Here detection performance of plasma-assisted CVD diamond is studied with the long-term objective of better understanding the detector degradation process and the detector lifetime in swift, heavy ion beam applications.

Detectors are fabricated using lab grown single crystal diamond at MSU that are first mechanically polished followed by chemical-mechanical polishing and/or plasma-assisted etching to reduce surface roughness. Some properties of the diamond material are characterized using birefringence, UV-VIS and FTIR (Fourier Transform Infrared spectroscopy) measurements. The detectors are characterized using capacitance and dark current (leakage current) measurement. The charge collection efficiency (CCE), the charge collection distance (CCD) and transient current characteristics are also studied for better realization of detectors performance. The detectors are tested with an alpha-particle source and by irradiation with a 150 MeV/u 78Kr beam. The detailed experimental characterization measurements are conducted both prior to and after the samples are irradiated with swift heavy ion beam to understand the effect of radiation damage.

This work was supported in part by SPG - MSU/MSU Foundation

 

A Novel Microfluidic Sensor Using Metamaterial Periodic Structure

Authors: Jennifer Byford; Kyoung Youl Park; Prem Chahal

Abstract: There is a growing demand for inexpensive sensors that can effectively detect changes in minute samples of liquids. Applications range from biomedical devices, lab on chip devices, environmental monitoring and forensic investigations. The proposed microstrip based microwave structure of this poster does not require calibration, does not require tagging, is simple and inexpensive to fabricate and can easily be miniaturized. Our structure, based on an open split ring resonator (OSRR) design, works by detecting dielectric changes in liquids as the liquids load the circuit. This dielectric loading interacts with the electric field around the structure and causes its resonant frequency to change. Given the shift in resonant frequency and change in amplitude, changes in the liquids loading the circuit can be determined. Multiple unit cells can be integrated on a single microstrip line to detect several samples in parallel and thus leading to high throughput. The structure and microfluidic channels were designed and simulated in the finite element analysis tool Ansoft HFSS. The structure was made using wet-etching techniques and the channel using a PDMS (Polydimethylsiloxane) mold. The sensor was tested as a single unit cell, in a three cell aperiodic array and as an array of three different sensors. Different concentrations of water-isopropanol (IPA) and water-methanol were used to characterize the sensor. Measurements are carried out using a network analyzer and resonance frequencies are determined. A biosensor application was demonstrated in detecting glucose-d concentration in deionized water.

 

Infrared Light Field Imaging Using Single Carbon Nanotube Detector

Authors: Liangliang Chen; Ning Xi; Ruiguo Yang; Bo Song; Zhiyong Sun; Zhanxin Zhou

Abstract: The conventional photographs only record the sum total of light rays of each point on image plane so that they tell little about the amount of light traveling along individual rays. The focus and lens aberration problems have challenged photographers since the very beginning and light field photography was proposed to solve these problems. Lens array and multiple camera systems were used to capture angular information, by reordering which the different views of scene were captured. The coded aperture is another method to encode the angular information in frequency domain.

However, lens aberration still is an inescapable problem when acquiring angular image. In the paper, we propose micro plane mirror optics, together with compressive sensing algorithm to record angular information to avoid aberration problem, which was named digital computational light field photography. The micro mirror reflects objects and forms a virtual image behind the plane in which the mirror lies. It consists of millions microscale mirror which works as CCD array in camera and it was controlled separately so as to project linear combination of object image on lens array. The carbon nanotube based infrared detector, which has ultra high signal to noise ratio, and fast responsibility, will sum up all image information on it, without image shape effect. Based on a number of measurements, compressive sensing algorithm was used to recovery angular image, and computed different views of scene to reconstruct infrared light field scence.

 

Modeling Of Natural Language Controlled Robotic Systems

Authors: Yu Cheng; Yunyi Jia; Rui Fang; Lanbo She; Ning Xi; Joyce Chai

Abstract: Instructing robots through natural language commands is an intuitive and flexible way to interact with robots by humans. It has tremendous advantages of reducing users’ recognition load, decreasing personnel cost and providing great convenience to untrained users, especially for the old and the disabled. Since robotic systems and humans have totally different structures, it is difficult for robots to understand natural language commands directly. Currently, extensive research has been focused on the action scheduling extracted from the natural language instructions, i.e., the translation from natural language input to a representation that the robots can understand. However, a more practical problem arises when implementing the generated action plans which is whether the performances of a robotic system can satisfy the given task specifications or not. Since current action scheduling processes are designed open-loop, the robotic system’s performances may not meet the desired requirements in face of modeling errors, system variations, and uncertainties. We propose a closed-loop action scheduling framework to handle unexpected events that may occur in both the robot side and the environment side. A minimum-cost action scheduling method is used to search for the shortest action sequence. Experimental results on a natural language controlled mobile manipulator demonstrate the effectiveness, advantages and robustness of the proposed method.

This work was supported in part by NSF: RC101957

  

GMM-MLFMA: A Fast Solver For Electromagnetic Scattering Problems

Authors: D. Dault; B. Shanker

Abstract: The ongoing explosion in radiative electromagnetic devices, from smartphones to wireless Internet to satellite communication, demands flexible and fast electromagnetic simulation capabilities. However, the efficient modeling of electromagnetic scattering and radiation from large and multiscale structures is a continuing open problem in the field of Computational Electromagnetics. This work provides a step forward in resolving this problem through the introduction of an acceleration methodology that hybridizes the recently developed Generalized Method of Moments (GMM), an electromagnetic integral equation method, with the Multilevel Fast Multipole Algorithm (MLFMA), the most widely used acceleration technique for electromagnetic integral equations. The resulting scheme combines the advantages of both methods. First, it harnesses the ability of GMM to provide quasi-optimal representations of electromagnetic fields via blending of local geometry and field representations over the surface of the target object. Second, it introduces spatial blending into the MLFMA acceleration algorithm, and therefore permits optimal acceleration of any mixture of lower and higher order field descriptions on discretizations of the scattering body using subdomains of arbitrary size. Traditional MLFMA approaches do not maintain optimal acceleration as subdomain size is varied, and applying MLFMA to discretizations with subdomains that are large with respect to a wavelength is an unsolved issue. The approach developed in this work is the first to maintain optimal MLFMA acceleration regardless of subdomain sizes, and furthermore retains its optimality for any arbitrary mixture of representations. The resulting method provides solutions to electromagnetic scattering and radiation problems that are both accurate and efficient relative to the current state of the art.

This work was supported in part by NSF Graduate Research Fellowship Program; NSF CCF-1018516; NSF CMMI-1250261

 

Improving The Boron Doping Efficiency Of Single Crystal Diamond

Authors: Shannon N. Demlow; Robert Rechenberg; Timothy A. Grotjohn

Abstract: As an electronic material, diamond would be particularly well suited to high-temperature and high-power devices, such as vertical Schottky Barrier diodes, due to its high breakdown voltage and carrier mobilities and exceptional thermal conductivity. Fabrication of high quality vertical diode structures necessitates freestanding, single crystal p-type diamond substrates, with low resistivity obtained through heavy doping (> 1020 cm-3). To achieve freestanding substrates, the diamond must be mechanically handleable after laser cutting from the growth substrate, and therefore thick ( > 300 μm). A problem of current interest in boron doped single crystal diamond (SCD) is the observation of decreasing doping efficiency at higher pressures (higher plasma discharge power) [1].

This work expands upon our previous effort to grow and characterize high-quality diamond for electrical applications [2], and examines the factors which contribute to increasing the gas chemistry to solid-phase doping efficiency. Homoepitaxial diamond is grown on type Ib high-pressure high-temperature (HPHT) SCD substrates in a microwave plasma-assisted chemical vapor deposition (MPACVD) bell-jar reactor with feedgas mixtures including hydrogen, methane, and diborane. We summarize strategies for increasing the boron doping efficiency of SCD, including the effects of deposition temperature, growth rate and total flow rate of the plasma feedgas.

References

[1] J. Achard, R. Issaoui, A. Tallaire, F. Silva, J. Barjon, F. Jomard, and A. Gicquel, Phys. Status Solidi A, 209 (2012) 1651-1658
[2] S. N. Demlow, I. Berkun, M. Becker, T. Hogan, and T. A. Grotjohn, MRS Proceedings, 1395, (2012)

This work was supported in part by II-VI Foundation Block-Gift Grant

 

Strongly Coupled Plasmas

Authors: Gautham Dharuman; John Verboncoeur; Andrew Christlieb

Abstract: Strongly Coupled Coulomb Plasmas are non-ideal plasmas with strong inter-particle interactions that dominate thermal motion. The strong correlations result in interesting properties that are absent in conventional plasmas. However, to understand these properties expensive computational studies are required due to the large number of particles and the associated interactions. Adding to the complexity are some quantum effects that are crucial in the dynamics of such plasmas. A complete quantum mechanical simulation is computationally prohibitive. This study focuses on semi-classical methods that can capture the essential quantum aspects within reasonable computational expense.

This work was supported in part by Air Force Office of Scientific Research (AFOSR)

 

Quantitative Assessment Of Customer Perception From Vehicle Service Data

Authors: Kalyanmoy Deb; Sunith Bandaru; Abhinav Gaur; Vineet Khare; Rahul Chougule

Abstract: We have developed a method for the quantitative modeling of a Customer Satisfaction Index (CSI) function for consumer vehicles. The mathematical model is evolved using an evolutionary computation technique such that the satisfied and dissatisfied customers are equally distributed on either side of the mean satisfaction level. Instead of relying on a conventional survey based assessment, we extract various important features from the service (field failure) data of five different vehicle models and build optimized CSI functions for each. The approach is extended so that a single CSI function can predict the satisfaction for all customers of all five models, thus providing a measure of the market’s perceived quality of one vehicle model relative to another. Different combinations of vehicle models are used and the corresponding CSI functions are validated against the ratings published by Consumer Reports. A sensitivity analysis reveals interesting information about the features extracted from the service data. Thereafter, the CSI function which best differentiates between all five vehicle models is chosen for further use. Finally, we present how such a model can be useful in gaining important insight into factors affecting the customer perception of vehicle quality and extract actionable knowledge, crucial from Customer Relationship Management (CRM) point of view, from the service data such as; (i) identifying high-priority problems for different vehicle models and (ii) identifying high priority customers customer-perception per se.

 

A Hermite Interpolatory Polynomial Basis For 3-D Finite Element Solution Of Electromagnetic Fields

Authors: Steve Hughey; John Albrecht; Balasubramaniam Shanker; Leo C. Kempel; L. R. Ram-Mohan

Abstract: Nedelec edge elements remain a popular choice when choosing a basis for the numerical solution of electromagnetic fields and have been extensively used in commercial applications; however, while this basis set naturally satisfies tangential continuity of fields across element interfaces, no such condition is imposed on normal components as is necessary to correctly represent electromagnetic fields. Additionally, electromagnetic problems involving both the vector and scalar potentials, prominent in the interaction of quantum mechanical states and electromagnetic fields, cannot be solved with a strictly vector basis set.

Hermite interpolatory polynomials were proposed as a basis set for scalar FEM modeling of electromagnetic fields in a waveguide as early as 1987 (Israel and Miniowitz, IEEE Trans. Microwave Theory Tech. MTT-35, 1019-1025, 1987). Recently, a method was introduced for deriving sets of minimal-order C^n interelement continuous Hermite interpolatory polynomials on triangles (Kassebaum, et al., J. Comput. Phys. 231, pp. 5747--5760, 2012). This interpolation method can specify continuity of not only tangential and normal fields at interelement surfaces, but their derivatives as well. Another recent work hybridizes Hermite interpolation methods with discontinuous Galerkin geometric discretizations in both 1-D and 2-D (Chen, et al., J. Comput. Phys. 257, pp. 501-520, 2014).

In this work, we will present the 3-D Hermite interpolatory basis set on tetrahedra. Several results will be presented to study the following: (i) h- and p-convergence of eigenvalues, (ii) convergence of field representation in piecewise inhomogeneous domains, (iii) comparison against higher order vector finite elements for field representation in complex topologies.

 

Modeling And Simulation Of Strongly Coupled Plasmas

Authors: Mayur Jain; John Verboncoeur; Andrew Christlieb

Abstract: This work focuses on the development of new modeling and simulation tools for studying SCP which differ from traditional plasmas in that their potential energy is larger than kinetic energy. The standard quasi neutral plasma model does not account for two major effects in SCP: 1) Change in the permittivity for modeling electromagnetic waves. 2) Impact on relaxation of charged particles undergoing Coulomb collisions with weakly shielded long range interactions. These objectives will be met through the development of: (i) Electrostatic particle based models based on PIC and Boundary integral Treecode (BIT) methods (ii) Electromagnetic particle based models based on PIC and new implicit particle methods based on treecodes (iii) Continuum models with long range correlations incorporated through fractional derivatives in time.

BIT is a mesh free method offering advantages in simulating resolved SCP with boundary conditions, whereas resolved PIC necessitates a prohibitively fine mesh when including boundary conditions. A treecode algorithm reduces operation count from O(N^2) to O(N log N). The particles are divided into a hierarchy of clusters and particle-particle interactions are replaced by particle-cluster interactions evaluated using multipole expansions. Treecodes use monopole approximations and a divide-and-conquer evaluation strategy and have been very successful in particle simulations with ongoing interest in optimizing their performance. BIT is an ideal method for studying strongly coupled electrostatic plasmas consisting 10^8 atoms. In this context BIT can be used to simulate a one to one representation of the ultra cold SCP, each particle representing a physical particle, naturally resolving long range interactions.

This work was supported in part by AFOSR

 

Design, Modeling And Control Of Mobile Manipulators

Authors: Yunyi Jia; Ning Xi

Abstract: The applications of standard manipulators are constrained in many areas due to their limited working spaces. Introducing mobile platforms to the standard manipulators can enlarge the working space and provide more flexibility for the robotic systems. However, adding mobile platforms to standard manipulators also introduces new challenges to the system design, modeling and control. We have designed two types of mobile manipulators. The first type is an indoor mobile manipulator by introducing a 4-castered-wheel holonomic mobile platform to a standard 6-DOF manipulator. The second type is an outdoor mobile manipulator by introducing a 4-rugged-wheel mobile platform to a standard 7-DOF manipulator. The system models of these two types of mobile manipulators are derived. The system controllers are built based on the system models and implemented on real-time control systems. A teleoperation system is development to remotely control these mobile manipulators. The effectiveness and advantages the designed mobile manipulator system are well demonstrated through applying it to different applications including human assistance, formation, and various material handling.

This work was supported in part by U.S. Army Research Office Contract No. W911NF-11-D-0001, and U.S. Army Research Office Grant No. W911NF-09-1-0321 and W911NF-10-1-0358, and National Science Foundation Award No. CNS-1320561 and IIS-1208390.

 

Defect Characterization In A 2D Steel Plate Using Non-Destructive Evaluation (NDE) Methods

Authors: Victor U. Karthik; Sivamayam Sivasuthan; S. Ratnajeevan H. Hoole

Abstract: When a steel plate in an army ground vehicle is found to be defective, usually it is taken out of service for repairing without determining if the defect warrants withdrawal or not, whereas the defect might be minor and withdrawal wasteful. On the other hand the defect might be invisible, yet warranting replacement. In our work we investigate and establish a procedure for defect characterization – thin crack, defect size and shape, spall, etc. – so that a decision to withdraw may be thought-out, justifiable and ensure the safety of the vehicle and its passengers. The methodology at present examines the response of the hull under test to an excitatory signal from an eddy current probe. Knowing the response when there is no defect, if the response is different because of the defect, the test object is presently flagged as defective and the vehicle sent for repairs without assessing if the defect is serious enough for removal from service. In this paper, we extend that methodology to defect characterization. A defect shape is characterized by parametric dimensions and properties( h) ̅, and we then solve the associated finite element problem with the defect, optimizing h ̅ until the computations match the measurements. The methodology is demonstrated by reconstructing a crack in a vehicle hull plate using eddy current probes. The problem is shown to be amenable to rapid analysis using the new GPU capabilities. This defect characterization would allow unseen serious defects to be flagged, and not allow minor defects leading to a vehicle being pulled out of service.

This work was supported in part by US Army TARDEC

  

Study Of Reduced Graphene Oxide Based Microwave Circuits On Flex Substrates

Authors: Amanpreet Kaur; Xianbo Yang; Premjeet Chahal

Abstract: Flex Radio frequency (RF) and microwave circuits enable various applications in wireless communication, security, bio-sensing and smart IDs. Although significant progress has been made in the area of flex circuits, fabrication of RF circuits still poses a significant challenge, esp. realization of active components. The material system used in the design of active circuits should have high carrier mobility at room temperature, good mechanical properties and ease of integration. Along with conventional semiconductors, various nanomaterials such as carbon nanotubes and graphene have been explored for RF applications. Carbon nanotubes (CNTs) and graphene have unique electrical properties such as high carrier mobility at room temperature; ballistic transport and micron-scale mean free paths. CNT based devices have high impedance and pose challenge in impedance matching which can be overcome with the use of graphene based devices.

This paper demonstrates fabrication and characterization of reduced graphene oxide (RGO) based RF devices on a flexible substrate. The current-voltage measurements show strong non-linearity. Diodes are tested for high frequency applications such as detection, frequency multiplication and mixing over a frequency range of 1 – 18 GHz. The devices show third order frequency multiplication for measured fundamental frequencies of 1, 2, 3, and 4 GHz and shows low-loss frequency mixing. Details of DC characteristics, RF rectification, mixing and multiplication using RGO Schottky diodes are presented.

This work was supported in part by the DARPA YFA program.

 

Characterization And Modeling Of Humidity-Dependence Of IPMC Sensing Dynamics

Authors: Hong Lei; Chaiyong Lim; Xiaobo Tan

Abstract: Ionic polymer-metal composites (IPMCs) have intrinsic actuation and sensing capabilities. For an IPMC sensor operating in air, the water content in the polymer varies with the humidity level of the ambient environment, which leads to its strong humidity-dependent sensing behavior. In this study, the influence of environmental humidity on IPMC sensors is characterized and modeled from a physical perspective. Specifically, a cantilevered IPMC beam is excited mechanically at its base inside a custom-built humidity chamber. We first obtain the empirical frequency responses of the sensor under different humidity levels, with the IPMC base displacement as input and the tip displacement and short-circuit current as outputs. Based on physics-based model for a given humidity level, we then curve-fit the measured frequency responses to identify the humidity-dependent physical parameters, including Young’s modulus, strain-rate damping coefficient, and viscous air damping coefficient for the mechanical properties, and ionic diffusivity for the mechanoelectrical dynamics. Static charging experiments of the IPMC are also conducted simultaneously, which are used to identify the effective dielectric constant. These parameters show a clear trend of change with the humidity. By fitting the identified parameters at a set of test humidity levels, the humidity-dependence of the physical parameters is captured with polynomial functions, which are then plugged into the physics-based model for IPMC sensors to predict the sensing output under other humidity conditions. The latter humidity-dependent model is further validated with experiments.

This work was supported in part by National Science Foundation (ECCS 0547131); the Office of Naval Research (N000140810640, N000141210149).

 

Diagnostics Of Atmospheric Pressure Microwave Generated Micro-Plasma By Using Optical Emission Spectroscopy

Authors: Peiyao Liu; Timothy A. Grotjohn

Abstract: Portable low-cost microplasma sources received interest in the past decade due to their various applications including materials processing, biomedical and chemical analysis, and optical radiation sources.[1-5] In particular, for atmospheric pressure microwave microplasmas that do not require vacuum systems, it is possible to realize 3D motion operation and portable lower-cost operation. Further, by using higher frequency energy (radio frequency and microwave) to power the microplasma discharge, non-LTE (non-local thermo-dynamic equilibrium) plasmas have the advantage of reducing the erosion of electrodes and also producing high power density plasmas with reasonably low power consumption.

In this investigation two microwave-powered microplasma systems are characterized using optical emission diagnostics. The first system is developed based on a double-strip-line structure. Top and bottom copper strip-lines are separated by a dielectric material. The structure is powered at one end and the plasma is formed at the other end where the two copper strip-lines are brought together to a gap with 250 microns separation. The feedgas is flowed through a channel in the dielectric such that it exits with the feedgas flowing into the gap created by the two strip-lines. The second system is constructed using a small foreshortened cylindrical cavity that has a hollow inner conductor and a small capacitive gap at the end of the cavity. The feedgas is flowed through a 2 mm inner diameter quartz tube which is located inside the hollow inner conductor of the cavity. Pure Argon, Argon-Oxygen mixtures (up to 10% Oxygen) and Argon-Hydrogen (with 2% hydrogen) are used as feedgas. The microwave power used for the discharges varies from 5 to 60 Watts. The flow rate of the feed-gases varies from 900 sccm - 2100 sccm. The optical emission spectroscopy technique was used to diagnose the discharges. Plasma properties such as rotational temperatures and electron densities under different conditions (power, flow rate and gas combinations) are measured and analyzed.

[1] J. Kim, M. Katsurai, D. Kim and H. Ohsaki, Appl. Phys. 93 (2008) 191594

[2] K. Ogata and K. Terashima, J. Appl. Phys., 106(2009) 023301
[3] J. Gregorio, L. L. Alves, O. Leroy, and C. Boisse-Laporte, Eur. Phys. J. D., 50(2010) 627

[4] S. Schermer, N. H. Bings, A. M. Bilgic, R. Stonies, E. Voges. J. A. C. Broekaert, Spectrochimica Acta Part B 58 (2003) 1585-1596

[5] U. Engel, A. M. Bilgic, O. Haase, E. Voges, and J. A. C.  Broekaert, Anal. Chem. 72(2000) 193

 

Robust Multi-Objective Evolutionary Optimization To Allow Greenhouse Production/Energy Use Tradeoffs

Authors: José R. Llera Ortiz; Erik Goodman

Abstract: The demand for fresh vegetables year-round has continuously sparked the search for ways to maintain this supply through the usage of greenhouses in a way that is both economically viable and environmentally friendly. The team proposes to use “Multi-Objective Compatible Control (MOCC)”, a form of evolutionary multi-objective optimization to dynamically balance the needs for productivity and the financial and environmental costs of greenhouse heating and supplementation. Classical optimization techniques are inadequate for systems like greenhouses with strongly coupled, nonlinear and time-varying states, and despite the computational cost, evolutionary multi-objective optimization is an attractive option when combined with acceptable model simplifications.

Central to this project are compatible control tradeoffs in greenhouse cultivation, so as to minimize energy consumption while preserving crop development, while also taking into account external weather conditions. To employ the MOCC strategy, the team has been using more mechanistic, dynamic models. In particular, ones suggested by [Vanthoor, Stanghellini and De Visser, 2011; Vanthoor, De Visser and Van Henten, 2011], are appropriate for this project, since these can model plant growth in a healthy, but not necessarily optimal growth environment, and is also structured for the crops and greenhouse construction being considered. The team has been working on a sophisticated model of the greenhouse internal environment and a crop model, which has shown reasonable growth dynamics which would allow full exploitation of MOCC-enhanced crop and resource management in greenhouses.

This work was supported in part by NSF/BEACON

 

Two-Dimensional Svd For Event Detection In Dynamic Functional Brain Networks

Authors: Arash Golibagh Mahyari; Selin Aviyente

Abstract: In recent years, there has been a growing interest in analyzing functional connectivity networks estimated from neuroimaging technologies using graph theory. Previous studies of the functional brain networks have focused on extracting static or time-independent networks to describe the long-term behavior of brain activity. In this paper, we propose a dynamic functional brain network tracking and summarization approach to describe the time-varying evolution of connectivity patterns in functional brain activity. The proposed approach is based on two-dimensional SVD of the three-mode tensor representation of dynamic graphs. First, the event intervals are identified based on the change in the reconstruction error in the lower dimensional space and then the activity in the event intervals are summarized. The proposed method is evaluated for characterizing time-varying network dynamics from event-related potential (ERP) data indexing the well-known error-related negativity (ERN) component related to cognitive control.

This work was supported in part by the National Science Foundation under Grant No. CCF-1218377.

 

Multi-Scale Anomaly Detection in Complex Dynamic Networks

Authors: Arash Golibagh Mahyari; Selin Aviyente


Abstract: Graphs arise naturally in a wide range of disciplines and applications since they capture the association between entities of a complex network. Recently, there has been an interest in time-evolving or dynamic graphs which can capture the change in the relational information across time. One important problem of interest in dynamic graphs is to detect the changes or anomalies in graph structure across time and identify the edges that conribute to these anomalies. In this paper, we propose a multi-scale analysis of dynamic graphs based on the Wavelet Packet Decomposition to separate the transient edge activity from the stationary background activity. Modeling the wavelet packet coefficients using a Gaussian Mixture Model, we derive a Neyman Pearson detector to identify anomalous edges both in time and space. Experiments illustrate the effectiveness of the method for both simulated and real dynamic networks.

This work was supported in part by the National Science Foundation under Grant No. CCF-1218377.


A Periodic Discontinuous Galerkin Time Domain Framework With A Floquet Mode Absorbing Boundary Condition

Authors: Nicholas Miller; Andrew Baczewski; John Albrecht; Balasubramaniam Shanker

Abstract: In electromagnetics and optics, periodic structures are important for effecting engineered frequency responses. Applications include conventional microwave frequency selective surfaces (FSS), metamaterials, or synthetic periodic systems that effect extraordinary properties. Numerical simulations offer an economical means for designing these periodic structures. Modeling becomes difficult when engineering designs require increasingly complex structures and broadband spectral content. For doubly infinite structures, the grid-based computational framework requires periodic and radiation boundary conditions to analyze broadband, higher order Floquet mode content. This framework should also be amenable to inhomogeneous, dispersive, and non-linear materials.

A computational framework which meets all this criteria is the nodal Discontinuous Galerkin Time Domain (DGTD) method. Recently, a periodic DGTD framework was developed to analyze homogeneous and lossless doubly periodic structures under oblique broadband excitation (Miller et al., pre-print, arXiv:1311.0790). This framework employed field transformations to render causal periodic boundary conditions and a planewave absorbing boundary condition (P-ABC) to truncate fundamental Floquet modes. The P-ABC, however, is shown to be insufficient for absorbing higher order Floquet content.

In this contribution, we will develop a formulation which relates the transformed electric field Floquet modes to magnetic field Floquet modes to properly absorb outward propagating scattered waves. The outward propagating solutions will be used as a Dirichlet boundary condition in the periodic numerical flux to truncate the computational domain. Results presented will validate our formulation and demonstrate utility for studying structures in which Floquet modes beyond zeroth order are excited.

This work was supported in part by the National Science Foundation through grant CCF:1018576.

  

Investigating The Dependencies And Limitations Of High Pressure Microwave Plasma Assisted Chemical Vapor Deposition Of Single Crystalline Diamond

Authors: Matthias Muehle; M. F. Becker; T. Schuelke; J. Asmussen

Abstract: Our research activities have focused on improving single crystalline diamond (SCD) growth rates and quality and also have been directed toward the development of microwave plasma reactors for high pressure diamond synthesis. Two new reactors, Reactor B and Reactor C have been developed. These reactors allow the safe and fast deposition of SCD material for pressures up to 300 Torr. However, the commercialization of an “electronic grade” SCD synthesis process requires the production of very high quality, large area SCD substrates at even higher growth rates. Increasing the SCD synthesis process pressure increases the growth rate and also seems to enhance crystalline quality. Here a new reactor, Reactor B’, is introduced, where a continuous wave (CW) microwave power supply is used. At high pressures exciting Reactor B with a 120 Hz pulse rate causes a flickering plasma ball and the plasma becomes unstable, thus it limits the safe and low maintenance operation of the reactor to an upper pressure limit of 280 Torr.

The results of a number of exploratory experiments using reactor B’ are presented. SCD deposition experiments were performed with process pressures up to 380 Torr (0.5 atm). A linear increase in growth rate versus pressure is observed. Additionally the dependency of the growth rate as a function of methane concentration is analyzed. For low concentrations a linear behavior has been identified, at higher methane concentrations (> 6-7%) the growth rate flattens out and appears to saturate versus additional increases of methane.

 

A Multi-Layered Metamaterial Inspired Dynamically Tunable Antenna

Authors: Joshua C. Myers; Premjeet Chahal; Edward Rothwell

Abstract: A multi-layered metamaterial inspired antenna with a pixel grid loading structure is introduced. The antenna consists of two layers separated by a thin dielectric substrate. The first layer contains a folded monopole antenna surrounded by a metal pixel based loading structure, while the second layer is envisioned to consist of a photoconductive pixel grid utilized to tune the antenna. The state of each pixel is controlled by a binary genetic algorithm, which is implemented with a Matlab-HFSS interface. HFSS simulations show that the second layer has a wide tuning ability with the appropriate state formed through optimization. As a proof of concept, the pixel grid on the second layer is initially made of a metal conductor. Multiple states corresponding to different resonant frequencies are selected and the antennas are constructed using conventional photolithography. The measured reflection coefficients are shown to be in good agreement with HFSS simulations, successfully demonstrating the ability to dramatically tune the antenna with a second pixel grid.

This work was supported in part by AFRL Research Grant

 

Performance And Efficiency Of Microwave Cavity Plasma Reactors Utilized In The Synthesis Of High Quality CVD Single Crystal Diamonds (SCDs)

Authors: Shreya Nad; Jes Asmussen

Abstract: High power and high pressure (100-300T) MPACVD reactors employ microwave discharges that provide an appropriate environment for synthesis of SCD. Microwave plasma reactors that operate in this high pressure regime must be able to sustain an efficient and stable high power density discharge hovering over the substrate. Recent reactor design advancements have led to an internally tunable microwave reactor [1]. This reactor has four independent geometry variables - short length (Ls), probe length (Lp), and reactor lengths (L1, L2). Here we investigate the nonlinear relationships between these mechanical variables and the usual input variables like pressure, power, substrate temperature, flow rate etc. Microwave coupling efficiency and substrate temperature are measured over the wide pressure, high input power regime as a stable plasma is formed and in contact with the substrate surface but placed away from the reactor walls. The reactor operating field map is experimentally defined and the diamond synthesis temperature window (700 – 1200°C) is determined. It is shown that as the substrate position varies the substrate temperature and the plasma shape can be varied with a modified discharge boundary layer. Regions where the reactor behaves in a safe and efficient manner are identified. Microwave coupling efficiencies of > 95% are demonstrated throughout the operating region and the mechanical variability of the reactor enables the optimization of the high quality SCD synthesis and yields a stable, controllable discharge over the entire pressure regime. This variability enables process control and process optimization over time.

[1] J.Asmussen, et.al. US Patent 8,316,797 (2012)

This work was supported in part by Block gift from II-VI foundation

 

General-Purpose Kinetic Global Modeling Framework For Multi-Phase Chemistry

Authors: Guy Parsey; Yaman Güçlü; John Verboncoeur; Andrew Christlieb

Abstract: Spatially averaged (global) models are ubiquitous in plasma science, and the required data and equations are conceptually very similar for most applications.

Unfortunately, it is common practice to implement a custom-developed software for each new global model; this unnecessary duplication of efforts negatively affects quality control and code maintenance. We present a general purpose kinetic global modeling framework (KGMf) designed to support plasma scientists in all modeling phases: collection and analysis of the reaction data, automatic construction of a system of ordinary differential equations (ODEs), time evolution of the system, and dynamical optimization of some target function.

Originally motivated by the study of plasma assisted combustion (PAC) systems, the KGMf incorporates both gas-phase and plasma driven reactions.

Accordingly, densities of each species, gas temperature, and electron effective temperature are evolved in time. The model generator can be used interactively, or with user defined control files, to manipulate the EEDF, boundary fluxes, and external forcing terms (e.g. MW/RF power). The ODE system is created first symbolically, for interactive manipulation, and then compiled to a standalone C function; this allowing for fast evaluation independent from the KGMf. Batch (parameter scanning) and result-search evaluation methods are included as Python modules for exploring the extensive parameter space of the physical model.

In order to demonstrate the capabilities and ease of use of the KGMf, we apply it to a plasma assisted system: CO2 dissociation with hydrocarbon catalyst.

This work was supported in part by MSU Strategic Partnership Grant

 

Full Wave Graphical Prpcessing Unit (GPU) Analysis Of Circular Guiding Structures Using The Finite Difference Frequency Domain (FDFD) Method

Authors: Mohammad R. Rawashdeh; Nihad I. Dib; S. Ratnajeevan H. Hoole

Abstract: Modeling and determining propagation characteristics of waveguides and transmission lines is very important for quick analysis in designing microwave circuits. In this research, full wave finite difference frequency domain (FDFD) will be presented to analyze different magnetically isotropic and non-isotropic circular cylindrical guiding structures. The FDFD equations are presented for both one and two dimensional structures according to the nature of the problem. The first step was finding the results which are obtained through solving these FDFD equations via the eigen-value problem using CPU computing languages like C/C++ or MATLA. The computed eigen-values and eigen-vectors are used to produce the propagation constants and the distribution of the fields. For ferrite loaded circular structures, full derivation and analysis is presented for completely filled azimuthally magnetized ferrite loaded coaxial lines and circular waveguides by using 2D-6FDFD and 1D-3FDFD equations. Most applications for azimuthally magnetized ferrite loaded coaxial lines and circular waveguides, such as isolators and phase shifters, operate using the TE0m modes. These TE0m modes are analyzed in detail in this research. The next step now is to use the benefits of the hardware accelerated scientific computing capability provided by graphics processing units(GPUs) to accelerate computations especially for complicated structures. CUDA-C will be used to build the needed algorithms in order to solve the eigen value problem of the FDFD.

 

Genre Categorization Of Amateur Sports Videos In The Wild

Authors: Seyed Morteza Safdarnejad; Xiaoming Liu; Lalita Udpa

Abstract: Various sports video genre categorization methods are proposed recently, mainly focusing on professional sports videos captured for TV broadcasting. This paper aims to categorize sports videos in the wild, captured using mobile phones by people watching a game or practicing a sport. Thus, no assumption is made about video production practices and existence of field lining and equipment. Motivated by distinctiveness of motions for many sports activities, we propose a novel motion trajectory descriptor to effectively and efficiently represent a video. Furthermore, we propose a temporal analysis algorithm of local descriptors that integrates the categorization decision over time. Extensive experiments on a newly collected dataset of amateur sports videos in the wild demonstrate that our trajectory descriptor is superior for sports videos categorization and temporal analysis of descriptors improves the categorization accuracy further.

 

Spherical Harmonic Expansion Method For Coupled Electron-Phonon Boltzmann Transport

Authors: Marco Santia; John Albrecht

Abstract: The thermal and electrical properties of semiconductors have traditionally been modeled by independent treatments for the phonon and charge carrier Boltzmann transport equations (BTE). These approaches, to varying degrees of approximation, work well near equilibrium and steady-state thus providing the baseline for many device simulations. Particle-based treatments, such as Monte Carlo methods, can in general allow for arbitrarily complex physical interactions but their stochastic nature has practical limitations for representing distribution functions in systems wide disparities in population. This work develops a coupled electron-phonon BTE based on a momentum-space spherical harmonic expansion (SHE) of the electron and phonon distribution functions and of the crystal eigenstates of electrons and phonons. We present a deterministic method which allows for detailed treatment of scattering processes comparable to particle solvers, yet alleviates the issues that arise in a system with populations ranging orders of magnitude from region to region in phase space. In this work we present the method formalism and examine the accuracy of the SHE for phonon band structures in GaN, scattering rates determined within that representation, and compare our preliminary results for distribution statistics in control examples such as thermal conductivity and drift velocity.

This work was supported in part by Office of Naval Research.

 

Extended Kalman Filtering For Remaining Useful Life (RUL) Estimation Of Bearings

Authors: Rodney Singleton II; Elias Strangas; Selin Aviyente

Abstract: Condition based maintenance, which includes both diagnosis and prognosis of faults, is a topic of growing interest in manufacturing, structural health monitoring and electrical drive operation. Although many signal processing and machine learning techniques have been successfully applied for fault identification and classification, prognosis of faults and especially predicting the remaining useful life (RUL) of the components is a remaining challenge. One reason for this challenge is lack of accurate physical models as well as the dependency of the existing algorithms to labeled training data. Bearings are one of the most widely used mechanical parts in rotational machinery and constitute a large portion of the failures. In this work, an extended Kalman filtering based framework is introduced to predict the RUL of bearing faults under different operating conditions and to provide a confidence interval to the RUL estimates. Various time domain features as well as joint time-frequency domain features are extracted from vibration signals and are used to define state space vectors to monitor the health of bearings and predict the remaining useful life. Performance of the prognosis method is evaluated on datasets from a test bed that generates bearing run-to-failure vibration data.

This work was supported in part by National Science Foundation under Grant No. EECS-1102316 and by the National Science Foundation Graduate Research Fellowship under Grant No. DGE-0802267.

 

A General Purpose Parameter Based Two Dimensional Mesh Generator For Seamless Optimization Problems

Authors: Sivamayam Sivasuthan; Victor. U. Karthik; S. Ratnajeevan H. Hoole

Abstract: In inverse electromagnetic problem solutions, parameter based mesh generation plays an essential role. As the geometry defined by parameters is optimized it changes shape, and a new finite element mesh must be created without stopping the optimization iterations to create a new mesh. Available mesh generators do not support such parameter based mesh generation without some manual input. This means that as optimization changes the shape we need to stop the program and make manual entry for a new mesh. The required mesh generator must therefore support parameter based mesh generation and be completely automatic once the optimization process begins – that means we must be able to change the physical shape of the problem during run time and generate the mesh. Such a mesh generator would help us implement a seamless optimization process in finite element analysis. This paper presents such an efficient, automatic, parameter-based mesh generator for optimization problems in finite element analysis. We present new software that can handle any general 2D geometrical shape and uses object oriented data structures to achieve superior performance. Examples of optimization carried out with this mesh generator are presented. Object oriented data structures are used to represent the problem. The software is developed in C/C++ and has been checked for many problems successfully.

This work was supported in part by TARDEC Grant No: RC103378

 

Ultra Accurate Positioning And Motion Control In SPM Based Nanomanipulation: Non-Vector Space Control With Hysteresis-Creep Hybrid Compensator

Authors: Bo Song; Ning Xi; Zhiyong Sun; Ruiguo Yang; Liangliang Chen

Abstract: Scanning probe microscopy (SPM) based nanomanipulations have been successfully applied in various fields such as physics, material science and biological studies. In general, the further development of SPM based nanomanipulation has been tackled due to the precision problem of tip positioning which is brought mainly by hysteresis and creep. In this research, a new approach for improving the positioning accuracy in multi-scale is proposed. In this approach, there are two steps to increase the positioning accuracy. First, a scan-range associated adaptive hysteresis-creep hybrid (SAH) compensator is design to compensate the non-linear hysteresis and linear rate-dependent creep effect of the open-loop SPM scanner to control the position error within 10 nanometers. Next an additional non-vector space controller is applied to further increase the accuracy using compressed image as the feedback. Because this controller is designed in a non-vector space, it does not require prior information on features or landmarks which are widely used in traditional visual servoing. In order to illustrate the contributions and potential applications of this control strategy, an application of carbon nanotube local electrical property characterization is shown to clearly verify the concept. Compared with other research in the local electrical property characterization, the non-vector space controller can ensure that the measurement accuracy (position error) is controlled within a few nanometers, which also ensures the reliability of measurement results. Additionally, this non-vector space control method can be implemented into any kind of SPM to realize a real-time control for nanomanipulation such as nanofabrication and nanoassembly.

This work was supported in part by NSF Grants IIS-0713346 and DMI-0500372; ONR Grants N00014-04-1-0799 and N00014-07-1-0935; NIH Grant: R43 GM084520

  

An Analytical Method For Constructing A Probabilistic Model Of A Wind Farm

Authors: Samer Sulaeman; Sirisha Tanneeru; Mohammed Benidris; Joydeep Mitra

Abstract: Wind energy penetration levels have increased in recent years all over the world. Despite the advantages of wind power, wind power introduces complexity to the planning and operation of power system due to output fluctuations. In addition, maintaining the efficiency, reliability and operation of the main power grid in present of intermittent resources has become avital challenge. For power systems, the intermittent nature and uncertainty of wind turbine generators (WTG) output power introduce complexity of applying traditional reliability methods to evaluate system reliability for planning and operation. In contrast to conventional generators, the operational characteristics of WTG add complexity to the reliability assessment methods applied on conventional generators. Since the output power of WTG depends mainly on wind speed regime in a particular wind farm geographical location, and mechanical availability of WTG, wind power output will exhibit variation due to the intermittent nature of wind speed which adds complexity of applying traditional techniques used for adequacy assessment of power system. Therefore, it is important to investigate the expected output power of wind turbines due to wind speed and mechanical availability. In addition, a model represents wind power should consider the intermittent nature of power output, and should also be applicable to meet with adequacy assessment techniques used for conventional generation with inclusion of variability and intermittency nature of wind power. This poster introduces a new method to model the output power of wind farms in reliability evaluation. The proposed model is presented in terms of capacity outage probability table (COPT) considering the mechanical failure of WTG and the correlation between the outputs of turbines on the same farm. Normal convolution methods are not applicable because the correlation between the turbines. Based on the proposed model, the COPT of wind farm has been constructed and applied on the IEEE RTS-79 to calculate the well known reliability indices. Furthermore, a comparison of the reliability indices with and without considering the mechanical failures of WTG is shown. The results indicate the importance of inclusion WTG mechanical availability in estimating reliability of wind power. The results were validated using Monte Carlo simulation.

 

Two-Dimensional Device Simulation Of Diamond Diodes

Authors: Nutthamon Suwanmonkha; Timothy Grotjohn

Abstract: Diamond semiconductor devices are of interest due to the exceptional properties of diamond including wide bandgap, high thermal conductivity, high breakdown electric field, and high electron and hole mobilities. While diamond has these exceptional properties, it also has a set of challenges associated with the substitutional donors and acceptors being deep. In particular the primary p-type dopant is boron and a promising n-type donor is phosphorus. Because of the deep level of the dopants, the behavior of the diamond electrical properties are temperature dependent in the 300-700K temperature range due to only partial dopant ionization.

This work uses the two-dimensional device simulation software (MEDICI) to model potential diamond diode designs. This work focuses at incorporating appropriate material parameters into the software for diamond to handle important effects including incomplete donor and acceptor ionization, avalanche breakdown, and temperature and impurity dependent mobility. These material parameters are based primarily on experimental data found in the research literature. The semiconductor device simulation software is then used to computationally model diamond diode structures including Schottky diodes, p-n junction diodes and merged diodes. Important device structures considered are the electrical contacts to the device including Ohmic contacts and Schottky contacts made of various metals. The diode simulations are compared to experimentally measured characteristics of various diamond diodes across a temperature range from 300-700K.

 

A Microwave Tomography System Using A Metamaterial-Inspired Tunable Reflectarray For Beam Steering

Authors: Amin Tayebi; Junyan Tang; Pavel Roy Paladhi; Lalita Udpa; Satish Udpa

Abstract: Microwave imaging using tomographic reconstruction has shown considerable promise in the fields of medical applications and NDE, particularly for the detection of anomalies in dielectric and composite laminate materials. Traditional microwave tomography systems use an array of transceivers placed around the area of interest to collect projection data 360o around the test object. However, the construction of such tomography systems using an array of transceivers is rather complex. This paper presents an alternate system that employs an electrically tunable beam-steering mirror coupled to a single microwave source which generates multi-angle projection data for tomographic reconstruction.

The tunable mirror can be built using reflectarray antennas. Reflectarrays are low-profile antennas inheriting the features of both reflector antennas and antenna arrays. The desired radiation pattern is shaped by changing the surface impedance of the array. In case of microstrip reflectarrays one way to do this is to manipulate individual elements (unit cell) of the array, such as physical size. However, to build a tunable reflectarray with beam steering capabilities, the unit cell characteristics should dynamically alter. In this work, beam steering is achieved by changing the capacitance of individual elements of the array using varactor diodes. Simulation and experimental measurements of a single unit cell of the reflectarray, the measured radiation pattern of the array and initial experimental results of the tomography system will be presented.

 

A Time-Varying Measure Of Phase Synchrony For Studying The Resting State Networks From Functional Magnetic Resonance Imaging

Authors: Marisel Villafane-Delgado; Selin Aviyente

Abstract: The study of resting state connectivity within the brain has been found to be of great utility in the study of neurological disorders. The resting-state networks are commonly studied through the blood-oxygen level-dependent (BOLD) response acquired from functional magnetic resonance imaging (fMRI). Current analysis techniques of resting-state fMRI networks rely mostly on linear measures, such as Pearson’s correlation. However, these methods cannot take into account the nonlinearities exhibited by the BOLD response and are susceptible to noise in the signals. Therefore alternative methods such as phase synchrony have been proposed to quantify the connectivity. The most common approaches to computing phase synchrony include the Hilbert transform and the Wavelet transform. This work introduces a measure of phase locking from the Rihaczek time-frequency distribution, which overcomes the drawbacks of other time-frequency phase locking methods such as time-frequency resolution tradeoff. In addition, as a time-frequency technique, this method has the advantage of avoiding the need of band-pass filtering the signal in a narrowband of frequencies for estimating the correlation in a particular frequency band, and provides information regarding to the spectro-temporal dynamics of synchrony. This work presents the assessment of whole brain synchrony with the isthmus of the cingulate cortex, and pairwise synchrony among areas included in the default-mode network (DMN). Results from the proposed method for estimating the phase synchrony are consistent with the definition of the DMN.

This work was supported in part by National Science Foundation

  

Design, Modeling And Control Of Autonoumous Robotic Fish

Authors: Jianxun Wang; Xiaobo Tan

Abstract: With five hundred years of evolution, fish and other aquatic animal are endowed with a variety of morphological and structural features that enable them to move through water with speed, efficiency and maneuverability. These remarkable feats have stimulated extensive theoretical, practical research by mathematicians and engineers, in an effort to understand and mimic locomotion, maneuvering, and sensing mechanism adopted by aquatic animals.

Over the past two decades, there has been significant interest in developing underwater robots that propel and maneuver themselves as real fish do. Often terms robotic fish, these robots provide an experimental platform for studying fish swimming, and hold strong promise for a number of underwater applications such as environmental monitoring.

In this poster, we present several bio-inspired robotic fish prototypes we have developed that make use of periodic tail motion for robust operations for a variety of applications e.g. studying live fish behavior, serving as educational tools. Mathematic models for these robots are presented to capture the interactions between them and the surrounding aquatic environment to predict their global motion. We also present a target tracking controller design approach, based upon the control-oriented average model that we recently developed.

This work was supported in part by National Science Foundation

 

In Vivo Tumor Interstitial Fluid Pressure Measurement Using Static Micro Force Sensor And Mechanical Tumor Model

Authors: Zhiyong Sun; Ruiguo Yang; Pavlo Kovalenko; Bo Song; Liangliang Chen; Mary F. Walsh; Marc D. Basson; Ning Xi

Abstract: Tumor interstitial fluid pressure (IFP) plays a major role in the microcirculatory process of the formation and growth of malignant tumors. The tumor growth phase is accompanied by remodeling of the vasculature and tumor-induced angiogenesis. Typically, the leakage from the newly formed blood vessels abnormal lymphatics often leads to the rise of IFP. The increase of IFP has been deemed as one of the main barriers to the transcapillary transport of therapeutic agents as well as the uptake of these large molecules, which depends upon fluid perfusion to penetrate into the tumor. Moreover, elevated IFP may also lead to the poor prognosis of some cancer patients. Therefore, the IFP can be an important indication of tumor growth and biology. The most common methodology of IFP measurement is the so-called “wick-in-needle” approach which employs a sharp needle to penetrate into the tumor. This method is invasive, and it cannot make continuous monitoring of the same tumor which is meaningful for drug testing.

To solve this problem, a potential non-invasive measurement technique was proposed to estimate the IFP using the applied force and the consequent deformation of the tumor surface. We used a sensitive Polyvinylidene Fluoride (PVDF) force sensor with drift-compensated numerical inverse approach to provide the force and developed a load-deformation mechanical tumor model to deduce the IFP. Convincing results were obtained to confirm the potential of the technique on measuring tumor inner pressure in vivo and non-invasively.

This work was supported in part by NSF Grants IIS-0713346 and DMI-0500372; ONR Grants N00014-04-1-0799 and N00014-07-1-0935; NIH Grant: R43 GM084520; and this work is approved by MSU IACUC.

 

GaAs Schottky Barrier Diode THz Image Sensor Based On Low-Cost, Large-Area Compatible Embedded Actives Heterogeneous Integration

Authors: Xianbo Yang; Premjeet Chahal

Abstract: The terahertz (THz) frequency spectrum (0.1-10THz) has drawn great research interest in the past few years, with a large amount of applications in communications, spectroscopy, imaging, sensing, and non-destructive evaluation. Existing THz systems are quasi-optical and bulky (table top systems), However, there is a growing demand to advance these setups from quasi-optical THz setup to integrated form in order to achieve similar benefits such as multi-functionality and low-cost provided by integrated circuits in the digital and RF area.

An approach to embed active devices for the fabrication of THz integrated circuits is presented in this paper. GaAs Schottky barrier diodes (SBDs) are integrated with broadband log-periodic antennas to demonstrate a THz imaging sensor. Calculated optical noise equivalent power (NEP) based on a measured I-V characteristic and diode small-signal equivalent model shows that a minimum value of 3.6 pW/Hz^(0.5) can be reached at 100GHz. Calculated and measured voltage sensitivity of the detector is shown to be closely matched to existing THz detectors. The detected image of a concealed object is also presented, which illustrates the reliability of the fabrication process and its ability to reduce parasitic elements associated with high frequency operation. The proposed fabrication approach is also large-area, low-cost, and low-temperature process compatible, which can also be implemented in heterogeneous integration of THz integrated circuits on a host of flexible substrates for variety of applications.

This work was supported in part by NSF.

 

Intelligent Electrochemical Gas Analysis System For Distributed Real-Time Health And Safety Monitoring

Authors: Heyu Yin; Haitao Li; Sam Boling; Yuning Yang; Lin Li; Andrew J. Mason

Abstract: Abstract:

Exposure to air pollution consistently ranks among the leading causes of illness and mortality globally, and the growing potential impact of airborne pollutants and explosive gases on human health and occupational safety has escalated the demand for sensors to monitor hazardous gases. Unfortunately, current preventative measures and treatments for air toxins are ineffective due in large part of our inability to properly characterize and quantify acute exposure to air pollutants. To overcome these challenges, a wearable autonomous multi-gas sensor system capable of real-time environmental monitoring could provide immediate feedback to warn the wearer of imminent environmental threats as well as a record of individual exposure that would aid the development of new treatment approaches. We present an Intelligent Electrochemical Gas Analysis System (iEGAS) that seeks to achieve this goal by synergistically integrating sensors, electronics, and data analysis algorithms into an autonomous wearable system. Electrochemical sensors featuring room temperature ionic liquid are utilized for low-power operation, high sensitivity and selectivity, and long life with low maintenance. A stacked platinum mesh electrode sensor structure enables miniaturization and rapid response. A custom multi-mode electrochemical instrumentation circuit combines all needed signal condition while minimizing system cost, size and power consumption. Embedded sensor array signal processing algorithms are being developed to enable gas classification and concentration estimation of a real-world mixture of gas analytes within the iEGAS system.

This work was supported in part by the National Institute for Occupational Safety and Health (NIOSH) under Grant R01OH009644

 

Gliding Robotic Fish: A Novel Underwater Robot For Aquatic Mobile Sensing

Authors: Feitian Zhang; Xiaobo Tan

Abstract: Aquatic ecosystems and processes exhibit a high degree of spatial and temporal heterogeneity, which presents significant challenges for their monitoring. In this poster, we report a novel underwater robot, called gliding robotic fish, as an emerging platform for mobile sensing in aquatic environments that can potentially provide high spatiotemporal coverage. The robot represents a hybrid of an underwater glider and a robotic fish, and is capable of exploiting gliding to achieve energy-efficient locomotion while using a fish-like active tail to achieve high maneuverability. The mechanical-electrical design of the robot is presented for the buoyancy control system, mass distribution system, and the tail control system. Two energy-efficient locomotion profiles are proposed, namely the sagittal-plane gliding motion and the three-dimensional spiraling motion, both of which consume almost zero energy for propulsion. We then show the dynamic modeling for such two motions and present the experimental validation results with the lab-developed prototype. The field-test results are also demonstrated, where the robot was used to sample the Kalamazoo River and the Wintergreen Lake in Michigan for concentrations of crude oil and harmful algae, respectively. Finally, we discuss some preliminary results of the extension of the current work to realize commercialization, including modular design for easier maintenance, solar panel for sustained battery recharging, and underwater optical communication for multi-agent networked sensing.

This work was supported in part by National Science Foundation (IIS 0916720, ECCS 1050236).

 

Optimal Compression Of A Generalized Prandtl-Ishlinskii Operator In Hysteresis Modeling

Authors: Jun Zhang; Emmanuelle Merced; Nelson Sepulveda; Xiaobo Tan

Abstract: Hysteresis is a nonlinear phenomenon that has been found in a wide range of areas, such as biology, economy, ferromagnetics, and various classes of smart materials-based systems. Being one of the most popular hysteresis models, the Prandtl-Ishlinskii model has been verified to be effective to capture such nonlinear behavior. The model is expressed as a weighted summation of elementary play operators. Each play operator is characterized by its play radius and weight. Existing work has typically adopted some predefined play radii for the play operators, and then identify the weights based on experimental data, the performance of which could be far from optimal. While it is true that the model will be more accurate when it consists of a larger number of play operators, computational complexity and data storage cost would also increase. In order to get an accurate model while maintaining relatively low calculation and storage cost, better schemes should be explored.

This work proposes a novel scheme to optimally approximate a high-fidelity Prandtl-Ishlinskii model with a large number of play operators, with a compressed Prandtl-Ishlinskii model with a lower number of play operators. The overall compression cost function is designed based on entropy theory and the optimal compression scheme is obtained by minimizing the cost function. The proposed compression scheme is applied to the modeling of the asymmetric hysteresis between resistance and temperature of a vanadium dioxide (VO2) film, and the effectiveness is further demonstrated in a model verification experiment. In particular, under the same complexity constraint, an entropy-based compression scheme results in modeling errors around only 37 % of that under a uniform compression scheme.

This work was supported in part by the National Science Foundation (ECCS 0547131, CMMI 0824830, CMMI 1301243). Emmanuelle Merced was supported by the National Science Foundation under Grant No. DGE-0802267 (Graduate Research Fellowship Program).

 

A Fast Rolling And High Jumping Robot

Authors: Jianguo Zhao; Weihan Yan; Ning Xi; Matt W. Mutka; Li Xiao

Abstract: In nature, many small insects or animals are able to move in difficult environments with obstacles with multiple locomotion methods. In this poster, we present our design of a miniature robot that can use legged wheels to fast roll on flat ground. Once encountering an obstacle, the robot can jump over it. Moreover, it has on-board energy, control, and communication abilities, which enables tetherless or autonomous operation. With the multi-modal locomotion abilities, the robot is expected to have many applications ranging from environmental monitoring, search and rescue, to military surveillance.

This work was supported in part by U.S. Army Research Office Contract No. W911NF-11-D-0001, and U.S. Army Research Office Grant No. W911NF-09-1-0321 and W911NF-10-1-0358, and National Science Foundation Award No. CNS-1320561 and IIS-1208390.

 

Transport Characterization Of Boron Doped Single Crystal Diamond Films

Authors: I. Berkun; S. Zajac; S.N. Demlow; T. Hogan; T.A. Grotjohn

Abstract: The need for electronic devices with higher power throughput, higher operating voltages and higher operational temperatures is driving the desire of fabricating new semiconductors with wider band gap such as diamond. Diamond for electronic applications requires doping to create semiconductor properties. This work is a continuation of our previous work, in which boron doped single crystal diamond (SCD) films were  deposited on high pressure high temperature SCD substrates in a microwave plasma-assisted chemical vapor deposition (MPACVD) bell-jar reactor with dopant concentrations from below 1017 cm-3 to over 1020 cm-3 [1].

An important need in the research of boron doped diamond semiconductors is the reliable determination of the critical electronic transport properties, such as the temperature dependent conductivity, carrier concentration, and carrier mobility of the deposited film.  This has previously been  reported with the influence of defects and theoretical model comparisons with experimental results [2].  High temperature Hall effect measurements  are essential in order to understand the properties of the SCD samples and provide feedback on the fabrication process. We have previously presented the high temperature Hall effect system which operates in the temperature range of 300K to 700K and was designed such that carrier concentrations and mobilities could be measured, as well as influences such as temperature stability and non-Ohmic contacts on the resulting measured values [3].

Temperature dependent Hall effect measurements have shown carrier concentrations from below 1017cm-3 to approximately 1021cm-3 with mobilities ranging from 763 (cm2/V•s) to 0.15 (cm2/V•s) respectively.  This work mainly focuses on the contact resistance studies for single crystal boron doped diamond using the transmission line method, effects of the contacts on the Hall effect measurements, and analysis of the resulting measurements including mixed carrier conduction modeling .

References

[1] S. N. Demlow, I. Berkun, M. Becker, T. Hogan, and T. A. Grotjohn, “Dopant Uniformity and Concentration in Boron Doped Single Crystal Diamond Films,” MRS Proceedings, 1395, (2012)
[2] Bormashov, V. S., S. A. Tarelkin, S. G. Buga, M. S. Kuznetsov, S. A. Terentiev, A. N. Semenov, and V. D. Blank. "Electrical properties of the high quality boron-doped synthetic single-crystal diamonds grown by the temperature gradient method." Diamond and Related Materials (2013).

[3] I. Berkun, S. N. Demlow, N. Suwanmonkha, T. P. Hogan, and T. A. Grotjohn, “Hall Effect Measurement System for Characterization of Doped Single Crystal Diamond,” MRS Proceedings, 1511 (2013)