In this paper we discuss eNERF, an extended version of non-Euclidean relational fuzzy c-means (NERFCM) for approximate clustering in very large (unloadable) relational data. The eNERF procedure consists of four parts:...
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A novel phase-modulation to intensity-modulation (PM-to-IM) converter is proposed and experimentally demonstrated basing on a vertical-cavity surface-emitting laser (VCSEL). Comparing with the published schemes, in wh...
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A novel phase-modulation to intensity-modulation (PM-to-IM) converter is proposed and experimentally demonstrated basing on a vertical-cavity surface-emitting laser (VCSEL). Comparing with the published schemes, in which the employed DI, FBG, OBPF or dispersion devices can only process a certain phase-modulated RF signal, the proposed scheme can achieve the conversion process in an economic and resourceful manner. To be the first one of achieving such PM-to-IM conversion process by a VCSEL, the feasibility of the proposal is experimentally demonstrated with an open eye diagram when it is employed to convert phase-modulated RF signal.
During the past decade, several research groups have begun to report unique spectroscopic results for mixed gas plasma systems in which one of the species present is hydrogen gas. In these experiments, researchers hav...
During the past decade, several research groups have begun to report unique spectroscopic results for mixed gas plasma systems in which one of the species present is hydrogen gas. In these experiments, researchers have reported excessive line broadening of H emission lines and peculiar non‐Boltzmann population of excited hydrogen states. The hydrogen line broadening in these studies has been attributed to Doppler broadening associated with anomalously high random translational velocity of H atoms (i.e. fast hydrogen). The spectroscopic data suggest the presence of a newly identified regime of energetic mixed gas hydrogen plasma systems, called resonant transfer (RT) plasmas. The data also suggest that these RT plasma systems have unique characteristics that warrant further exploration for propulsion applications. Preliminary calculations suggest that a microwave RT plasma thruster could achieve performance several orders of magnitude greater than chemical rocket propulsion. Accordingly, the NASA Institute for Advanced Concepts (NIAC) has funded a study aimed at assessing the potential of RT plasmas for propulsion applications. This paper will discuss the results of the NIAC Phase I study including spectroscopic characterization of the RT plasma, development of RT plasma thruster hardware and preliminary test firing of two separate RT plasma thrusters.
This paper contains a thermodynamic analysis of electron emission from a micro-fabricated diamond tip array. The analysis is based on experimental measurements of the current-voltage characteristics of an actual devic...
This paper contains a thermodynamic analysis of electron emission from a micro-fabricated diamond tip array. The analysis is based on experimental measurements of the current-voltage characteristics of an actual device. Field enhancement, applied field, and electrical current density are shown to influence thermodynamic performance. The idealized thermodynamic analysis predicts cooling rates above 10 W/cm2 for an existing device under room temperature operation and that 100 W/cm2 may be possible for future devices.
Deep learning models currently achieve human levels of performance on real-world face recognition tasks. We review scientific progress in understanding human face processing using computational approaches based on dee...
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Deep learning models currently achieve human levels of performance on real-world face recognition tasks. We review scientific progress in understanding human face processing using computational approaches based on deep learning. This review is organized around three fundamental advances. First, deep networks trained for face identification generate a representation that retains structured information about the face (e.g., identity, demographics, appearance, social traits, expression) and the input image (e.g., viewpoint, illumination). This forces us to rethink the universe of possible solutions to the problem of inverse optics in vision. Second, deep learning models indicate that high-level visual representations of faces cannot be understood in terms of interpretable features. This has implications for understanding neural tuning and population coding in the high-level visual cortex. Third, learning in deep networks is a multistep process that forces theoretical consideration of diverse categories of learning that can overlap, accumulate over time, and interact. Diverse learning types are needed to model the development of human face processing skills, cross-race effects, and familiarity with individual faces.
This paper describes the first stage of a research project to develop an automated vehicle for inspecting the structural integrity of concrete sewer pipelines. We have developed an innovative interrogation and signal ...
This paper describes the first stage of a research project to develop an automated vehicle for inspecting the structural integrity of concrete sewer pipelines. We have developed an innovative interrogation and signal processing algorithm for detecting and sizing defects in concrete media, irrespective of the composition of the concrete—a crucial factor for realizing an in-line inspection process for concrete pipes. We have simulated concrete pipeline inspection by fabricating concrete specimens of diverse compositions embedded with rectangular defects of varying depths immersed in synthetic wastewater of varying density. We present ultrasonic C-scans and their corresponding defect characterization profiles.
Ballistic Electron Emission Microscopy (BEEM) and finite‐element electrostatic modeling were used to quantify how “small‐size” effects modify the energy barrier at metal/semiconductor nanostructure nanocontacts, f...
Ballistic Electron Emission Microscopy (BEEM) and finite‐element electrostatic modeling were used to quantify how “small‐size” effects modify the energy barrier at metal/semiconductor nanostructure nanocontacts, formed by making Schottky contacts to cleaved edges of GaAs quantum wells (QWs). The Schottky barrier height over the QWs was found to systematically increase with decreasing QW width, by up to ∼140 meV for a 1nm QW. This is mostly due to a large quantum‐confinement increase (∼200 meV for a 1nm QW), modified by smaller decreases due to “environmental” electric field effects. Our modeling gives excellent quantitative agreement with measurements for a wide range of QW widths when both quantum confinement and environmental electric fields are considered.
Work towards the development of an innovative, potentially high power density, MEMS loop heat pipe is in progress at the Center for Microelectronic Sensors and M E M S at the University of Cincinnati. The design of th...
Work towards the development of an innovative, potentially high power density, MEMS loop heat pipe is in progress at the Center for Microelectronic Sensors and M E M S at the University of Cincinnati. The design of the loop heat pipe is based upon the very unique coherent porous silicon technology, a technique in which vast arrays of micrometer ‐ sized through ‐ holes are photo ‐ electrochemically etched into a silicon wafer perpendicular to the (100) surface. The initial mathematical model, the design, fabrication and characterization of the device in the open loop configuration were previously reported at this conference, STAIF 2002. This paper begins with a very brief explanation of the device and its theory of operation. The design of the device components and their production utilizing the various techniques of microelectronic and microelectromechanical fabrication are presented. The modifications made to the photon ‐ induced, electrochemical etch process, which significantly increase the etch rate of the pores, are explained. Attention is given to the mathematical model of the planar, MEMS, loop heat pipe with respect to the generation of the dimensions of the components through a summary of the recent advances. The emphasis of this paper is upon the design, construction and the characterization of the evacuated closed loop test cell structure.
Electromigration failure under DC stress has been studied for more than 30 years, and the methodologies for accelerated DC testing and design rules have been well established in the IC industry. However, the electromi...
Electromigration failure under DC stress has been studied for more than 30 years, and the methodologies for accelerated DC testing and design rules have been well established in the IC industry. However, the electromigration behavior and design rules under time-varying current stress are still unclear. In CMOS circuits, as many interconnects carry pulsed-DC (local VCC and VSS lines) and bidirectional AC current (clock and signal lines), it is essential to assess the reliability of metallization systems under these conditions. Failure mechanisms of different metallization systems (Al-Si, Al-Cu, Cu, TiN/Al-alloy/TiN, etc.) and different metallization structures (via, plug and interconnect) under AC current stress in a wide frequency range (from mHz to 500 MHz) has been study in this paper. Based on these experimental results, a damage healing model is developed, and electromigration design rules are proposed. It shows that in the circuit operating frequency range, the “design-rule current” is the time-average current. The pure AC component of the current only contributes to self-heating, while the average (DC component) current contributes to electromigration. To ensure longer thermal-migration lifetime under high frequency AC stress, an additional design rule is proposed to limit the temperature rise due to self-joule heating.
In this paper, the development of a fundamentally new, topology‐based cable sensor design concept is summarized for crack detection in reinforced concrete (RC) structures. The sensitivity, spatial resolution, and sig...
In this paper, the development of a fundamentally new, topology‐based cable sensor design concept is summarized for crack detection in reinforced concrete (RC) structures. The sensitivity, spatial resolution, and signal loss of sensors are investigated both numerically and experimentally. Two sensors were fabricated and validated with small‐ and large‐scale laboratory tests under different loads. Both were proven sensitive to crack of various sizes from visually undetectable to excessive, giving the location and severity of damage simultaneously. One sensor has been installed on a three‐span bridge for its long‐term monitoring. It is capable of recording damage that has occurred during a recent event.
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