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Recent Advances On Shm Of Reinforced Concrete And Masonry Structures Enabled By Self-Sensing Structural Materials, Filippo Ubertini, Antonella D’Alessandro, Austin Downey, Enrique García-Macías, Simon Laflamme, Rafael Castro-Triguero 2018 University of Perugia

Recent Advances On Shm Of Reinforced Concrete And Masonry Structures Enabled By Self-Sensing Structural Materials, Filippo Ubertini, Antonella D’Alessandro, Austin Downey, Enrique García-Macías, Simon Laflamme, Rafael Castro-Triguero

Simon Laflamme

Structural Health Monitoring is aimed at transforming civil structures into self-diagnosing systems able to automatically reveal the occurrence of a fault or a damage after a critical event such as an earthquake. While data science is presently experiencing tremendous advances leading to the availability of powerful tools and algorithms for extracting relevant information by effectively fusing data provided by different types of sensors, one of the main bottlenecks still limiting the development of SHM in the field of civil engineering is the general lack of reliable sensing technologies that are scalable at the large scale. A very promising solution to ...


Robust Variable Input Observer For Structural Health Monitoring Of Systems Experiencing Harsh Extreme Environments, Jonathan Hong, Liang Cao, Simon Laflamme, Jacob Dodson 2018 Iowa State University

Robust Variable Input Observer For Structural Health Monitoring Of Systems Experiencing Harsh Extreme Environments, Jonathan Hong, Liang Cao, Simon Laflamme, Jacob Dodson

Simon Laflamme

Systems experiencing events in the order of 10μs-10ms timescales, for instance highrate dynamics or harsh extreme environments, may encounter rapid damaging effects. If the structural health of such systems could be accurately estimated in a timely manner, preventative measures could be employed to minimize adverse effects. Previously, a Variable Input Observer (VIO) coupled with a neuro-observer was proposed by the authors as a potential solution in monitoring their structural health. The objective of the VIO is to provide state estimation based on an optimal input space allowed to vary as a function of time. The VIO incorporates the use of ...


Novel Nanocomposite Clay Brick For Strain Sensing In Structural Masonry, F. Ubertini, A. D'Alessandro, A. L. Materazzi, Simon Laflamme, Austin Downey 2018 University of Perugia

Novel Nanocomposite Clay Brick For Strain Sensing In Structural Masonry, F. Ubertini, A. D'Alessandro, A. L. Materazzi, Simon Laflamme, Austin Downey

Simon Laflamme

The monitoring of civil structures is critical in ensuring users' safety. Structural health monitoring (SHM) is the automation of this monitoring task. It is typically used to identify incipient damages through a spatio-temporal comparison in structural behaviors. Traditional sensors exhibit mechanical characteristics that are usually very different from those of the structures they monitor, which is a factor limiting their durability. Ideally, the material of a sensor would share the same mechanical characteristics as the material onto or into which it is installed. A solution is to fabricate multifunctional materials, capable of serving both structural and sensing functions, also known ...


Microsecond State Monitoring Of Nonlinear Time-Varying Dynamic Systems, Jacob Dodson, Bryan Joyce, Simon Laflamme, Janet Wolfson 2018 Air Force Research Laboratory

Microsecond State Monitoring Of Nonlinear Time-Varying Dynamic Systems, Jacob Dodson, Bryan Joyce, Simon Laflamme, Janet Wolfson

Simon Laflamme

Reliable operation of next generation high-speed complex structures (e.g. hypersonic air vehicles, space structures, and weapons) relies on the development of microsecond structural health monitoring (μSHM) systems. High amplitude impacts may damage or alter the structure, and therefore change the underlying system configuration and the dynamic response of these systems. While state-of-the-art structural health monitoring (SHM) systems can measure structures which change on the order of seconds to minutes, there are no real-time methods for detection and characterization of damage in the microsecond timescales.

This paper presents preliminary analysis addressing the need for microsecond detection of state and parameter ...


Experimental Damage Detection Of Wind Turbine Blade Using Thin Film Sensor Array, Austin Downey, Simon Laflamme, Filippo Ubertini, Partha Sarkar 2018 Iowa State University

Experimental Damage Detection Of Wind Turbine Blade Using Thin Film Sensor Array, Austin Downey, Simon Laflamme, Filippo Ubertini, Partha Sarkar

Simon Laflamme

Damage detection of wind turbine blades is difficult due to their large sizes and complex geometries. Additionally, economic restraints limit the viability of high-cost monitoring methods. While it is possible to monitor certain global signatures through modal analysis, obtaining useful measurements over a blade's surface using off-the-shelf sensing technologies is difficult and typically not economical. A solution is to deploy dedicated sensor networks fabricated from inexpensive materials and electronics. The authors have recently developed a novel large-area electronic sensor measuring strain over very large surfaces. The sensing system is analogous to a biological skin, where local strain can be ...


Adaptive Structural Control Using Dynamic Hyperspace, Simon Laflamme 2018 Iowa State University

Adaptive Structural Control Using Dynamic Hyperspace, Simon Laflamme

Simon Laflamme

The design of closed-loop structural control systems necessitates a certain level of robustness to cope with system uncertainties. Neurocontrollers, a type of adaptive control system, have been proposed to cope with those uncertainties. However, the performance of neural networks can be substantially influenced by the choice of the input space, or the hyperspace in which the representation lies. For instance, input selection may influence computation time, adaptation speed, effects of the curse of dimensionality, understanding of the representation, and model complexity. Input space selection is often overlooked in literature, and inputs are traditionally determined offline for an optimized performance of ...


A Robust Signal Processing Method For Quantitative High-Cycle Fatigue Crack Monitoring Using Soft Elastomeric Capacitor Sensors, Xiangxiong Kong, Jian Li, William Collins, Caroline Bennett, Simon Laflamme, Hongki Jo 2018 University of Kansas

A Robust Signal Processing Method For Quantitative High-Cycle Fatigue Crack Monitoring Using Soft Elastomeric Capacitor Sensors, Xiangxiong Kong, Jian Li, William Collins, Caroline Bennett, Simon Laflamme, Hongki Jo

Simon Laflamme

A large-area electronics (LAE) strain sensor, termed soft elastomeric capacitor (SEC), has shown great promise in fatigue crack monitoring. The SEC is able to monitor strain changes over a mesoscale structural surface and endure large deformations without being damaged under cracking. Previous tests verified that the SEC is able to detect, localize, and monitor fatigue crack activities under low-cycle fatigue loading. In this paper, to examine the SEC’s capability of monitoring high-cycle fatigue cracks, a compact specimen is tested under cyclic tension, designed to ensure realistic crack opening sizes representative of those in real steel bridges. To overcome the ...


Continuous And Embedded Solutions For Shm Of Concrete Structures Using Changing Electrical Potential In Self-Sensing Cement-Based Composites, Austin Downey, Enrique Garcia-Macias, Antonella D'Alessandro, Simon Laflamme, Rafael Castro-Triguero, Filippo Ubertini 2018 Iowa State University

Continuous And Embedded Solutions For Shm Of Concrete Structures Using Changing Electrical Potential In Self-Sensing Cement-Based Composites, Austin Downey, Enrique Garcia-Macias, Antonella D'Alessandro, Simon Laflamme, Rafael Castro-Triguero, Filippo Ubertini

Simon Laflamme

Interest in the concept of self-sensing structural materials has grown in recent years due to its potential to enable continuous low-cost monitoring of next-generation smart-structures. The development of cement-based smart sensors appears particularly well suited for monitoring applications due to their numerous possible field applications, their ease of use and long-term stability. Additionally, cement-based sensors offer a unique opportunity for structural health monitoring of civil structures because of their compatibility with new or existing infrastructure. Particularly, the addition of conductive carbon nanofillers into a cementitious matrix provides a self-sensing structural material with piezoresistive characteristics sensitive to deformations. The strain-sensing ability ...


Damage Detection And Localization Algorithm Using A Dense Sensor Network Of Thin Film Sensors, Austin Downey, Filippo Ubertini, Simon Laflamme 2018 Iowa State University

Damage Detection And Localization Algorithm Using A Dense Sensor Network Of Thin Film Sensors, Austin Downey, Filippo Ubertini, Simon Laflamme

Simon Laflamme

The authors have recently proposed a hybrid dense sensor network consisting of a novel, capacitive-based thin-film electronic sensor for monitoring strain on mesosurfaces and fiber Bragg grating sensors for enforcing boundary conditions on the perimeter of the monitored area. The thin-film sensor monitors local strain over a global area through transducing a change in strain into a change in capacitance. In the case of bidirectional in-plane strain, the sensor output contains the additive measurement of both principal strain components. When combined with the mature technology of fiber Bragg grating sensors, the hybrid dense sensor network shows potential for the monitoring ...


Damage Location And Quantification Of A Pretensioned Concrete Beam Using Stochastic Subspace Identification, Alessandro Cancelli, Laura Micheli, Simon Laflamme, Alice Alipour, Sri Sritharan, Filippo Ubertini 2018 Iowa State University

Damage Location And Quantification Of A Pretensioned Concrete Beam Using Stochastic Subspace Identification, Alessandro Cancelli, Laura Micheli, Simon Laflamme, Alice Alipour, Sri Sritharan, Filippo Ubertini

Sri Sritharan

Stochastic subspace identification (SSID) is a first-order linear system identification technique enabling modal analysis through the time domain. Research in the field of structural health monitoring has demonstrated that SSID can be used to successfully retrieve modal properties, including modal damping ratios, using output-only measurements. In this paper, the utilization of SSID for indirectly retrieving structures’ stiffness matrix was investigated, through the study of a simply supported reinforced concrete beam subjected to dynamic loads. Hence, by introducing a physical model of the structure, a second-order identification method is achieved. The reconstruction is based on system condensation methods, which enables calculation ...


Introduction To State Estimation Of High-Rate System Dynamics, Jonathan Hong, Simon Laflamme, Jacob Dodson, Bryan Joyce 2018 Iowa State University

Introduction To State Estimation Of High-Rate System Dynamics, Jonathan Hong, Simon Laflamme, Jacob Dodson, Bryan Joyce

Civil, Construction and Environmental Engineering Publications

Engineering systems experiencing high-rate dynamic events, including airbags, debris detection, and active blast protection systems, could benefit from real-time observability for enhanced performance. However, the task of high-rate state estimation is challenging, in particular for real-time applications where the rate of the observer’s convergence needs to be in the microsecond range. This paper identifies the challenges of state estimation of high-rate systems and discusses the fundamental characteristics of high-rate systems. A survey of applications and methods for estimators that have the potential to produce accurate estimations for a complex system experiencing highly dynamic events is presented. It is argued ...


Randomized Routing On Fat-Trees, Ronald I. Greenberg, Charles E. Leiserson 2018 Loyola University Chicago

Randomized Routing On Fat-Trees, Ronald I. Greenberg, Charles E. Leiserson

Ronald Greenberg

Fat-trees are a class of routing networks for hardware-efficient parallel computation. This paper presents a randomized algorithm for routing messages on a fat-tree. The quality of the algorithm is measured in terms of the load factor of a set of messages to be routed, which is a lower bound on the time required to deliver the messages. We show that if a set of messages has load factor lambda on a fat-tree with n processors, the number of delivery cycles (routing attempts) that the algorithm requires is O(lambda + lg n lg lg n) with probability 1-O(1/n). The ...


The Fat-Pyramid And Universal Parallel Computation Independent Of Wire Delay, Ronald I. Greenberg 2018 Loyola University Chicago

The Fat-Pyramid And Universal Parallel Computation Independent Of Wire Delay, Ronald I. Greenberg

Ronald Greenberg

This paper shows that a fat-pyramid of area Θ(A) requires only O(log A) slowdown to simulate any competing network of area A under very general conditions. The result holds regardless of the processor size (amount of attached memory) and number of processors in the competing networks as long as the limitation on total area is met. Furthermore, the result is valid regardless of the relationship between wire length and wire delay. We especially focus on elimination of the common simplifying assumption that unit time suffices to traverse a wire regardless of its length, since the assumption becomes more ...


Randomized Routing On Fat-Trees, Ronald I. Greenberg 2018 Selected Works

Randomized Routing On Fat-Trees, Ronald I. Greenberg

Ronald Greenberg

Fat-trees are a class of routing networks for hardware-efficient parallel computation. This paper presents a randomized algorithm for routing messages on a fat-tree. The quality of the algorithm is measured in terms of the load factor of a set of messages to be routed, which is a lower bound on the time required to deliver the messages. We show that if a set of messages has load factor lambda on a fat-tree with n processors, the number of delivery cycles (routing attempts) that the algorithm requires is O(lambda+lgnlglgn) with probability 1-O(1/n). The ...


Universal Wormhole Routing, Ronald I. Greenberg, Hyeong-Cheol Oh 2018 Selected Works

Universal Wormhole Routing, Ronald I. Greenberg, Hyeong-Cheol Oh

Ronald Greenberg

In this paper, we examine the wormhole routing problem in terms of the “congestion” c and “dilation” d for a set of packet paths. We show, with mild restrictions, that there is a simple randomized algorithm for routing any set of P packets in O(cdη+cLηlogP) time with high probability, where L is the number of flits in a packet, and η=min{d,L}; only a constant number of flits are stored in each queue at any time. Using this result, we show that a fat-tree network of area Θ(A) can simulate wormhole routing on any network ...


Single-Layer Channel Routing And Placement With Single-Sided Nets, Ronald I. Greenberg, Jau-Der Shih 2018 Selected Works

Single-Layer Channel Routing And Placement With Single-Sided Nets, Ronald I. Greenberg, Jau-Der Shih

Ronald Greenberg

This paper considers the optimal offset, feasible offset, and optimal placement problems for a more general form of single-layer VLSI channel routing than has usually been considered in the past. Most prior works require that every net has exactly one terminal on each side of the channel. As long as only one side of the channel contains multiple terminals of the same net, we provide linear-time solutions to all three problems. Such results are implausible if the placement of terminals is entirely unrestricted; in fact, the size of the output for the feasible offset problem may be Ω(n^2 ...


On The Difficulty Of Manhattan Channel Routing, Ronald I. Greenberg, Joseph JaJa, Sridhar Krishnamurthy 2018 Loyola University Chicago

On The Difficulty Of Manhattan Channel Routing, Ronald I. Greenberg, Joseph Jaja, Sridhar Krishnamurthy

Ronald Greenberg

We show that channel routing in the Manhattan model remains difficult even when all nets are single-sided. Given a set of n single-sided nets, we consider the problem of determining the minimum number of tracks required to obtain a dogleg-free routing. In addition to showing that the decision version of the problem isNP-complete, we show that there are problems requiring at least d+Omega(sqrt(n)) tracks, where d is the density. This existential lower bound does not follow from any of the known lower bounds in the literature.


On The Area Of Hypercube Layouts, Ronald I. Greenberg, Lee Guan 2018 Selected Works

On The Area Of Hypercube Layouts, Ronald I. Greenberg, Lee Guan

Ronald Greenberg

This paper precisely analyzes the wire density and required area in standard styles for the hypercube. It shows that the most natural, regular layout of a hypercube of N^2 nodes in the plane, in a NxN grid arrangement, uses floor(2N/3)+1 horizontal wiring tracks for each row of nodes. (In the process, we see that the number of tracks per row can be reduced by 1 with a less regular design, as can also be seen from an independent argument of Bezrukov et al.) This paper also gives a simple formula for the wire density at any ...


Minimum Separation For Single-Layer Channel Routing, Ronald I. Greenberg, F. Miller Maley 2018 Loyola University Chicago

Minimum Separation For Single-Layer Channel Routing, Ronald I. Greenberg, F. Miller Maley

Ronald Greenberg

We present a linear-time algorithm for determining the minimum height of a single-layer routing channel. The algorithm handles single-sided connections and multiterminal nets. It yields a simple routability test for single-layer switchboxes, correcting an error in the literature.


Mulch: A Multi-Layer Channel Router Using One, Two, And Three Layer Partitions, Ronald I. Greenberg, Alex T. Ishii, Alberto L. Sangiovanni-Vincentelli 2018 Loyola University Chicago

Mulch: A Multi-Layer Channel Router Using One, Two, And Three Layer Partitions, Ronald I. Greenberg, Alex T. Ishii, Alberto L. Sangiovanni-Vincentelli

Ronald Greenberg

Chameleon, a channel router for three layers of interconnect, has been implemented to accept specification of an arbitrary number of layers. Chameleon is based on a strategy of decomposing the multilayer problem into two- and three-layer problems in which one of the layers is reserved primarily for vertical wire runs and the other layer(s) for horizontal runs. In some situations, however, it is advantageous to consider also layers that allow the routing of entire nets, using both horizontal and vertical wires. MulCh is a multilayer channel router that extends the algorithms of Chameleon in this direction. MulCh can route ...


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