Engineering Commons^™

Sensor Validation Using Bayesian Networks, Ole J. Mengshoel, Adnan Darwiche, Serdar Uckun

Ole J Mengshoel

One of NASA’s key mission requirements is robust state estimation. Sensing, using a wide range of sensors and sensor fusion approaches, plays a central role in robust state estimation, and there is a need to diagnose sensor failure as well as component failure. Sensor validation techniques address this problem: given a vector of sensor readings, decide whether sensors have failed, therefore producing bad data. We take in this paper a probabilistic approach, using Bayesian networks, to diagnosis and sensor validation, and investigate several relevant but slightly different Bayesian network queries. We emphasize that onboard inference can be performed on a …

Linear Current-Mode Active Pixel Sensor, Ralf M. Philipp, David Orr, Viktor Gruev, Jan Van Der Spiegel, Ralph Etienne-Cummings

Jan Van der Spiegel

A current mode CMOS active pixel sensor (APS) providing linear light-to-current conversion with inherently low fixed pattern noise (FPN) is presented. The pixel features adjustable-gain current output using a pMOS readout transistor in the linear region of operation. This paper discusses the pixel’s design and operation, and presents an analysis of the pixel’s temporal noise and FPN. Results for zero and first-order pixel mismatch are presented. The pixel was implemented in a both a 3.3 V 0.35 µm and a 1.8 V 0.18 µm CMOS process. The 0.35 µm process pixel had an uncorrected FPN of 1.4%/0.7% with/without column readout …

A Fully Integrated Cmos Phase-Locked Loop With 30mhz To 2ghz Locking Range And ±35 Ps Jitter, Chao Xu, Winslow Sargeant, Kenneth R. Laker, Jan Van Der Spiegel

Jan Van der Spiegel

A fully integrated phase-locked loop (PLL) fabricated in a 0.24μm, 2.5v digital CMOS technology is described. The PLL is intended for use in multi-gigabit-per-second clock recovery circuits in fiber-optic communication chips. This PLL first time achieved a very large locking range measured to be from 30MHz up to 2GHz in 0.24μm CMOS technologies. Also it has very low peak-to-peak jitter less than ±35ps at 1.25GHz output frequency.

Analytical And Experimental Studies Of Thermal Noise In Mosfet's, Suharli Tedja, Jan Van Der Spiegel, Hugh H. Williams

Jan Van der Spiegel

An analysis of the channel thermal noise in MOSFET's, based on the one-dimensional charge sheet model, is presented. The analytical expression is valid in the strong, moderate, and weak inversion regions. The body effect on the device parameters relevant to the thermal noise is discussed. A measurement technique as well as experimental results of P- and N-MOSFET's of a 1.2 µm radiation hard CMOS process are presented. The calculated channel thermal noise coefficient gamma as in id2/Δf=4kT γ gdo agrees well with experimental data for effective device channel length as short as 1.7µm.

Background Digital Error Correction Technique For Pipelined Analog-Digital Converters, Sameer R. Sonkusale, Jan Van Der Spiegel, K. Nagaraj

Jan Van der Spiegel

This paper describes a technique for digital error correction in pipelined analog-digital converters. It makes use of a slow, high resolution ADC in conjunction with an LMS algorithm to perform error correction in the background during normal conversion. The algorithm will be shown to correct for errors due to capacitor ratio mismatch, finite amplifier gain and charge injection within the same framework.

Fully Integrated Cmos Phase-Locked Loop With 30mhz To 2ghz Locking Range And +-35ps Jitter, Chao Xu, Winslow Sargeant, Kenneth R. Laker, Jan Van Der Spiegel

Jan Van der Spiegel

A fully integrated phase-locked loop (PLL) fabricated in a 0.24 micrometer, 2.5v digital CMOS technology is described. The PLL is intended for use in multi-gigabit-per-second clock recovery circuits in fiber-optic communication chip. This PLL first time achieved a very large locking range measured to be from 30MHz up to 2GHz in 0.24 micrometer CMOS technology. Also it has very low peak-to-peak jitter less than +-35ps at 1.25GHz output frequency.

Gbopcad: A Synthesis Tool For High-Performance Gain-Boosted Opamp Design, Jie Yuan, Nabil H. Farhat, Jan Van Der Spiegel

Jan Van der Spiegel

A systematic design methodology for high-performance gain-boosted opamps (GBOs) is presented. The methodology allows the optimization of the GBO in terms of ac response and settling performance and is incorporated into an automatic computer-aided design (CAD) tool, called GBOPCAD. Analytic equations and heuristics are first used by GBOPCAD to obtain a sizing solution close to the global optimum. Then, simulated annealings are used by GBOPCAD to find the global optimum. A sample opamp is designed by this tool in a 0.6-μm CMOS process. It achieves a dc gain of 80 dB, a unity-gain bandwidth of 836 MHz with 60o phase …

Human Behavior Models For Agents In Simulators And Games: Part Ii Gamebot Engineering With Pmfserv, Barry G. Silverman, Gnana K. Bharathy, Kevin O'Brien, Jason Cornwell

Barry G Silverman

Many producers and consumers of legacy training simulator and game environments are beginning to envision a new era where psycho-socio-physiologic models could be interoperated to enhance their environments' simulation of human agents. This paper explores whether we could embed our behavior modeling framework (described in the companion paper, Part 1) behind a legacy first person shooter 3D game environment to recreate portions of the Black Hawk Down scenario. Section 1 amplifies the interoperability needs and challenges confronting the field, presents the questions that are examined, and describes the test scenario. Sections 2 and 3 review the software and knowledge engineering …

Human Behavior Models For Agents In Simulators And Games: Part I: Enabling Science With Pmfserv, Barry G. Silverman, Michael Johns, Jason Cornwell, Kevin O'Brien

Barry G Silverman

This article focuses on challenges to improving the realism of socially intelligent agents and attempts to reflect the state of the art in human behavior modeling with particular attention to the impact of personality/cultural values and affect as well as biology/stress upon individual coping and group decision-making. The first section offers an assessment of the state of the practice and of the need to integrate valid human performance moderator functions (PMFs) from traditionally separated sub-fields of the behavioral literature. The second section pursues this goal by postulating a unifying architecture and principles for integrating existing PMF theories and models. It …

Achieving Transparency With Plasmonic And Metamaterial Coatings, Andrea Alù, Nader Engheta

Nader Engheta

The possibility of using plasmonic and metamaterial covers to drastically reduce the total scattering cross section of spherical and cylindrical objects is discussed. While it is intuitively expected that increasing the physical size of an object may lead to an increase in its overall scattering cross section, here we see how a proper design of these lossless metamaterial covers near their plasma resonance may induce a dramatic drop in the scattering cross section, making these objects nearly “invisible” or “transparent” to an outside observer—a phenomenon with obvious applications for low-observability and noninvasive probe design. Physical insights into this phenomenon and …

Guided Modes In A Waveguide Filled With A Pair Of Single-Negative (Sng), Double-Negative (Dng), And/Or Double-Positive (Dps) Layers, Andrea Alù, Nader Engheta

Nader Engheta

Here we present the results of our theoretical analysis for guided modes in parallel-plate waveguides filled with pairs of parallel layers made of any two of the following materials: 1) a material with negative real permittivity, but positive real permeability (epsilon-negative); 2) a material with negative real permeability, but positive real permittivity (mu-negative); 3) a material with both negative real permittivity and permeability (double-negative); and 4) a conventional material with both positive real permittivity and permeability (double-positive) in a given range of frequency. Salient properties of these guided modes are studied in terms of how these materials and their parameters …

Electromagnetic Wave Propagation In The Wire Medium: A Complex Medium With Long Thin Inclusions, Charles Anthony Moses, Nader Engheta

Nader Engheta

The wire medium is a type of complex artificial material we conceptually envision as many identical finite-length, parallel, thin wire inclusions embedded within a host medium. It is representative of a class of novel artificial materials characterized by long thin inclusions. Unlike some conventional artificial material, the inclusions of this class are not necessarily electrically short. Here, we present our theoretical analysis for wire media and by studying certain salient features of plane-wave propagation through these media, introduce equivalent medium parameters that depend, among other parameters, on the direction of wave propagation. The approach we use separates the artificial material …

Theory And Simulations Of A Conformal Omni-Directional Sub-Wavelength Metamaterial Leaky-Wave Antenna, Andrea Alù, Filiberto Bilotti, Nader Engheta, Lucio Vegni

Nader Engheta

The detailed theory of a single subwavelength conformal radiator that exploits the resonant properties of thin cylindrical metamaterial shells supporting leaky waves is presented. It is shown and reviewed analytically and numerically how a circularly symmetric resonant leaky mode may be supported by a properly designed subwavelength homogenous cylindrical shell of low negative permittivity. Some physical insights are provided and numerical simulations with a feed point, considering also the finiteness of the antenna in the longitudinal direction, are presented and discussed. Moreover, possibilities and limitations of a practical realization of this setup are mentioned, considering in details the possible anisotropies …

Radiation Characteristics Of Microstrip Dipole Antennas Over A High-Impedance Metamaterial Surface Made Of Hilbert Inclusions, John Mcvay, Ahmad Hoorfar, Nader Engheta

Nader Engheta

We analyze numerically the radiation characteristics of center-fed microstrip short dipoles and half-wave dipoles near a high-impedance surface made of Hilbert shape flat inclusions. We study the input impedance, pattern and gain of such radiating structures. We show that the radiation resistance of a microstrip dipole increases noticeably at certain frequencies near the resonant frequency of the Hilbert surface. Moreover, antenna gain enhancement at certain frequencies is observed for all dipole sizes we have analyzed.

Far-Field Subdiffraction Optical Microscopy Using Metamaterial Crystals: Theory And Simulations, Alessandro Salandrino, Nader Engheta

Nader Engheta

Here we suggest and explore theoretically an idea for a far-field scanless optical microscopy with a subdiffraction resolution. We exploit the special dispersion characteristics of an anisotropic metamaterial crystal that is obliquely cut at its output plane, or has a curved output surface, in order to map the input field distribution onto the crystal’s output surface with a compressed angular spectrum, resulting in a "magnified" image. This can provide a far-field imaging system with a resolution beyond the diffraction limits while no scanning is needed.

Subwavelength, Compact, Resonant Patch Antennas Loaded With Metamaterials, Andrea Alù, Filiberto Bilotti, Nader Engheta, Lucio Vegni

Nader Engheta

We analyze the matching and radiation properties of subwavelength resonant patch antennas filled with double-negative, double-positive, and/or single-negative metamaterial blocks. Analyzing the theoretical limits inherently present when loading such common radiators with metamaterials, we show how these configurations may exhibit in principle an arbitrarily low resonant frequency for a fixed dimension, but they may not necessarily radiate efficiently when their size is electrically small. However, interesting possibilities are suggested to overcome these limitations by employing circular or more complex patch geometries in order to select specific modes that, when appropriate loading ratios between the filling materials are chosen, also ensure …

Bandwidth, Cross-Polarization, And Feed-Point Characteristics Of Matched Hilbert Antennas, Jinhui Zhu, Ahmad Hoorfar, Nader Engheta

Nader Engheta

In this work, we have applied a moment-method-based simulation code to perform a detailed parametric study of the bandwidth, cross-polarization level, and the feed location characteristics of the matched Hilbert antenna. It is shown that a properly chosen off-center near-the-end feed point may provide an approximate 50-Ω real input impedance at the fundamental resonant frequency. The role of different iteration order for Hilbert antennas, approximately matched to 50-Ω line, on the bandwidth and cross-polarization level of such antennas are investigated numerically. As was shown by Vinoy et al. the radiation patterns resemble those of a linear dipole and for a …

Circuit Elements At Optical Frequencies: Nanoinductors, Nanocapacitors, And Nanoresistors, Nader Engheta, Alessandro Salandrino, Andrea Alù

Andrea Alù

We present the concept of circuit nanoelements in the optical domain using plasmonic and nonplasmonic nanoparticles. Three basic circuit elements, i.e., nanoinductors, nanocapacitors, and nanoresistors, are discussed in terms of small nanostructures with different material properties. Coupled nanoscale circuits and parallel and series combinations are also envisioned, which may provide road maps for the synthesis of more complex circuits in the IR and visible bands. Ideas for the optical implementation of right-handed and left-handed nanotransmission lines are also forecasted.

Pairing An Epsilon-Negative Slab With A Mu-Negative Slab: Resonance, Tunneling And Transparency, Andrea Alù, Nader Engheta

Andrea Alù

Here, we analyze the transverse-magnetic (TM) wave interaction with a pair of slabs, one being an epsilon-negative (ENG) layer in which the real part of permittivity is assumed to be negative while its permeability has positive real part, and the other being a mu-negative (MNG) layer that has the real part of its permeability negative but its permittivity has positive real part. Although wave interaction with each slab by itself has predictable features, we show that the juxtaposition and pairing of such ENG and MNG slabs may, under certain conditions, lead to some unusual features, such as resonance, complete tunneling, …

Theory And Simulations Of A Conformal Omni-Directional Sub-Wavelength Metamaterial Leaky-Wave Antenna, Andrea Alù, Filiberto Bilotti, Nader Engheta, Lucio Vegni

Andrea Alù

The detailed theory of a single subwavelength conformal radiator that exploits the resonant properties of thin cylindrical metamaterial shells supporting leaky waves is presented. It is shown and reviewed analytically and numerically how a circularly symmetric resonant leaky mode may be supported by a properly designed subwavelength homogenous cylindrical shell of low negative permittivity. Some physical insights are provided and numerical simulations with a feed point, considering also the finiteness of the antenna in the longitudinal direction, are presented and discussed. Moreover, possibilities and limitations of a practical realization of this setup are mentioned, considering in details the possible anisotropies …

Achieving Transparency With Plasmonic And Metamaterial Coatings, Andrea Alù, Nader Engheta

Andrea Alù

The possibility of using plasmonic and metamaterial covers to drastically reduce the total scattering cross section of spherical and cylindrical objects is discussed. While it is intuitively expected that increasing the physical size of an object may lead to an increase in its overall scattering cross section, here we see how a proper design of these lossless metamaterial covers near their plasma resonance may induce a dramatic drop in the scattering cross section, making these objects nearly “invisible” or “transparent” to an outside observer—a phenomenon with obvious applications for low-observability and noninvasive probe design. Physical insights into this phenomenon and …

Guided Modes In A Waveguide Filled With A Pair Of Single-Negative (Sng), Double-Negative (Dng), And/Or Double-Positive (Dps) Layers, Andrea Alù, Nader Engheta

Andrea Alù

Here we present the results of our theoretical analysis for guided modes in parallel-plate waveguides filled with pairs of parallel layers made of any two of the following materials: 1) a material with negative real permittivity, but positive real permeability (epsilon-negative); 2) a material with negative real permeability, but positive real permittivity (mu-negative); 3) a material with both negative real permittivity and permeability (double-negative); and 4) a conventional material with both positive real permittivity and permeability (double-positive) in a given range of frequency. Salient properties of these guided modes are studied in terms of how these materials and their parameters …

Gravimetric Chemical Sensor Based On The Direct Integration Of Swnts On Aln Contour-Mode Mems Resonators, Matteo Rinaldi, Chiara Zuniga, Nipun Sinha, Marzie Taheri, Samuel Khamis, Alan Johnson, Gianluca Piazza

Matteo Rinaldi

This paper reports on the first demonstration of a gravimetric chemical sensor based on direct integration of Single Wall Carbon Nanotubes (SWNTs) grown by Chemical Vapor Deposition (CVD) on AlN Contour-Mode MicroElectroMechanical (MEMS) resonators. In this first prototype the ability of SWNTs to readily adsorb volatile organic chemicals has been combined with the capability of AlN Contour-Mode MEMS resonator to provide for different levels of sensitivity due to separate frequencies of operation on the same die. Two devices with resonance frequencies of 287 MHz and 442 MHz have been exposed to different concentrations of DMMP in the range from 80 …

Boeing Welliver Faculty Fellowship, Raúl Ordóñez

Raúl Ordóñez

$25500.

Motoman Robotics Laboratory, Raúl Ordóñez

Raúl Ordóñez

PI, funded by Motoman in kind and UD in matching funds, $1M, established fall 2008. Supported by SAS, Sick, others.

A Framework For Evaluating Managerial Styles In Open Source Projects, Tony Wasserman, Eugenio Capra

Tony Wasserman

This paper presents the Software Project Governance Framework (SPGF) for characterizing management of software projects, based on mechanisms used for communication and collaboration, the organizational structure of projects, and testing and quality assurance procedures. The framework was developed and validated from interviews and surveys with leaders of more than 70 commercial and community based software projects, including both closed and open source projects.

Mitigation Of Control Channel Jamming Under Node Capture Attacks, Patrick Tague, Mingya Li, Radha Poovendran

Patrick Tague

Availability of service in many wireless networks depends on the ability for network users to establish and maintain communication channels using control messages from base stations and other users. An adversary with knowledge of the underlying communication protocol can mount an efficient denial of service attack by jamming the communication channels used to exchange control messages. The use of spread spectrum techniques can deter an external adversary from such control channel jamming attacks. However, malicious colluding insiders or an adversary who captures or compromises system users are not deterred by spread spectrum, as they know the required spreading sequences. For …

On Collision-Tolerant Transmission With Directional Antennas, Hong-Ning Dai, Kam-Wing Ng, Min-You Wu

Hong-Ning Dai

The application of directional antennas in wireless networks brings numerous benefits, such as increased spatial reuse and mitigated interferences. Most MAC protocols with directional antennas are based on the RTS/CTS mechanism which works well in wireless networks using omni-directional antennas. However, RTS/CTS frames cannot mitigate the interfering nodes completely. Besides, they also contribute a lot to the performance overhead. This paper studies the problem from a new perspective. We analyze the transmission success probability under directional transmission and directional reception when the antenna beamwidth is quite narrow. Motivated by the analytical results, we design a lightweight MAC protocol without RTS/CTS …

On The Capacity Of Multi-Channel Wireless Networks Using Directional Antennas, Hong-Ning Dai, Kam-Wing Ng, Raymond Chi-Wing Wong, Min-You Wu

Hong-Ning Dai

The capacity of wireless ad hoc networks is affected by two key factors: the interference among concurrent transmissions and the number of simultaneous transmissions on a single interface. Recent studies found that using multiple channels can separate concurrent transmissions and greatly improve network throughput. However, those studies only consider that wireless nodes are equipped with only omnidirectional antennas, which cause high collisions. On the other hand, some researchers found that directional antennas bring more benefits such as reduced interference and increased spatial reuse compared with omnidirectional antennas. But, they only focused on a single-channel network which only allows finite concurrent …

Cascading Infrastructure Failures: Avoidance And Response, George H. Baker, Cheryl J. Elliott

George H Baker

No critical infrastructure is self-sufficient. The complexity inherent in the interdependent nature of infrastructure systems complicates planning and preparedness for system failures. Recent wide-scale disruption of infrastructure on the Gulf Coast due to weather, and in the Northeast due to electric power network failures, dramatically illustrate the problems associated with mitigating cascading effects and responding to cascading infrastructure failures once they have occurred.

The major challenge associated with preparedness for cascading failures is that they transcend system, corporate, and political boundaries and necessitate coordination among multiple, disparate experts and authorities. This symposium brought together concerned communities including government and industry …