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Articles 1 - 7 of 7
Full-Text Articles in Engineering
Performance Bounds For Grouped Incoherent Measurements In Compressive Sensing, Adam Polak, Marco Duarte, Dennis Goeckel
Performance Bounds For Grouped Incoherent Measurements In Compressive Sensing, Adam Polak, Marco Duarte, Dennis Goeckel
Marco Duarte
Compressive sensing (CS) allows for acquisition of sparse signals at sampling rates significantly lower than the Nyquist rate required for bandlimited signals. Recovery guarantees for CS are generally derived based on the assumption that measurement projections are selected independently at random. However, for many practical signal acquisition applications, including medical imaging and remote sensing, this assumption is violated as the projections must be taken in groups. In this paper, we consider such applications and derive requirements on the number of measurements needed for successful recovery of signals when groups of dependent projections are taken at random. We find a penalty …
Universality Of Wavelet-Based Non-Homogeneous Hidden Markov Chain Model Features For Hyperspectral Signatures, Siwei Feng, Marco Duarte, Mario Parente
Universality Of Wavelet-Based Non-Homogeneous Hidden Markov Chain Model Features For Hyperspectral Signatures, Siwei Feng, Marco Duarte, Mario Parente
Marco Duarte
Feature design is a crucial step in many hyperspectral signal processing applications like hyperspectral signature classification and unmixing, etc. In this paper, we describe a technique for automatically designing universal features of hyperspectral signatures. Universality is considered both in terms of the application to a multitude of classification problems and in terms of the use of specific vs. generic training datasets. The core component of our feature design is to use a non-homogeneous hidden Markov chain (NHMC) to characterize wavelet coefficients which capture the spectrum semantics (i.e., structural information) at multiple levels. Results of our simulation experiments show that the …
Compressive Parameter Estimation Via Approximate Message Passing, Marco Duarte
Compressive Parameter Estimation Via Approximate Message Passing, Marco Duarte
Marco Duarte
No abstract provided.
Tr-2015-1 Preliminary Hydraulic Design Of A Step-Pool-Type, Nature-Like Fishway (3/30/15), Brett Towler, James Turek, Alex Haro
Tr-2015-1 Preliminary Hydraulic Design Of A Step-Pool-Type, Nature-Like Fishway (3/30/15), Brett Towler, James Turek, Alex Haro
Brett Towler
This technical report presents a method for the preliminary hydraulic design of a step-pool type, nature-like fishway. The method and its companion example, “Nature-Like Fishway at the Obex Mills dam site”, are presented as an instructional exercise illustrating how one may bridge the gap between a conceptual layout and subsequent, more detailed, design phases. This report is intended to supplement the “Federal Interagency Nature-like Fish Passage Guidelines for Atlantic Coast Diadromous Fishes” (unpublished; forthcoming 2015).
Nanoimprint Lithography 20 Years On, Qiangfei Xia, R. Fabian Pease
Nanoimprint Lithography 20 Years On, Qiangfei Xia, R. Fabian Pease
Qiangfei Xia
To celebrate the 20th anniversary of nanoimprint lithography (NIL) we present a perspective of how the technique and its prospects have evolved over the past two decades. We describe how it overcame certain fabrication challenges at the time it was first reported and look at some of the obstacles that hindered uptake in industry initially, as well as likely sectors for future successful commercial deployment. Developments in the technique since that are making NIL increasingly attractive such as 'moving roll to roll' for higher throughput, are also described.
Nanoscale Memristive Radiofrequency Switches, Shuang Pi, Mohammad Ghadiri-Sadrabadi, Joseph C. Bardin, Qiangfei Xia
Nanoscale Memristive Radiofrequency Switches, Shuang Pi, Mohammad Ghadiri-Sadrabadi, Joseph C. Bardin, Qiangfei Xia
Qiangfei Xia
Radiofrequency switches are critical components in wireless communication systems and consumer electronics. Emerging devices include switches based on microelectromechanical systems and phase-change materials. However, these devices suffer from disadvantages such as large physical dimensions and high actuation voltages. Here we propose and demonstrate a nanoscale radiofrequency switch based on a memristive device. The device can be programmed with a voltage as low as 0.4 V and has an ON/OFF conductance ratio up to 1012 with long state retention. We measure the radiofrequency performance of the switch up to 110 GHz and demonstrate low insertion loss (0.3 dB at 40 GHz), …
General Properties For Determining Power Loss And Efficiency Of Passive Multi-Port Microwave Networks, Ramakrishna Janaswamy
General Properties For Determining Power Loss And Efficiency Of Passive Multi-Port Microwave Networks, Ramakrishna Janaswamy
Ramakrishna Janaswamy
Starting from the scattering matrix formulation, three useful properties are derived that characterize the dissipative loss and the corresponding efficiency of a multiport, passive microwave network. Elementary examples are considered that involve both reciprocal and non-reciprocal networks to demonstrate the utility of the expressions provided. When applied to the equal-split, matched, 3-port resistive divider, they recover the known fact that the device is 50% efficient. The relations yield the new result that the efficiency of a 3-port Wilkinson power divider is 2/3 on the average. Using the results presented it is further shown that the Wilkinson power divider belongs to …