| A Multiple Time-Step Finite State Projection Algorithm for the Solution to the Chemical Master Equation |
30 NOV 2006 |
21 pages |
| Authors:
Brian Munsky; Mustafa Khammash; CALIFORNIA UNIV SANTA BARBARA DEPT OF MECHANICAL AND ENVIRONMENTAL ENGINEERING
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 | At the mesoscopic scale, chemical processes have probability distributions that evolve according to an infinite set of linear ordinary differential equations known as the chemical master equation (CME). It is commonly believed that the CME cannot be solved except for the most trivial of cases, but recent work has raised questions regarding validity of this belief. For many cases, Finite State Projection (FSP) techniques can reduce the order of the ... |
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| Passive Control of Limit Cycle Oscillations in a Thermoacoustic System using Asymmetry |
05 SEP 2006 |
15 pages |
| Authors:
Bryan Eisenhower; Gregory Hagen; Andrzej Banaszuk; Igor Mezic; CALIFORNIA UNIV SANTA BARBARA DEPT OF MECHANICAL AND ENVIRONMENTAL ENGINEERING
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| In this paper, we investigate oscillations of a dynamical system containing passive dynamics driven by a positive feedback and how spatial characteristics (i.e. symmetry) affect the amplitude and stability of its nominal limit cycling response. The physical motivation of this problem is thermoacoustic dynamics in a gas turbine combustor. The spatial domain is periodic (passive annular acoustics) which are driven by heat released from a combustion process, and with sufficient ... |
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| An Extension of the Argument Principle and Nyquist Criterion to Systems with Unbounded Generators |
17 APR 2006 |
8 pages |
| Authors:
Makan Fardad; Bassam Bamieh; CALIFORNIA UNIV SANTA BARBARA DEPT OF MECHANICAL AND ENVIRONMENTAL ENGINEERING
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| The Nyquist Stability Criterion is generalized to systems where the (open-loop) system has infinite-dimensional input/output spaces and a (possibly) unbounded infinitesimal generator. This is done through use of the perturbation determinant and an extension of the Argument Principle to infinitesimal generators with trace-class resolvent. |
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| Effects of Surface Slope on Erosion Rates of Quartz Particles |
MAR 2006 |
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| Authors:
Phillip Lodge; CALIFORNIA UNIV SANTA BARBARA DEPT OF MECHANICAL AND ENVIRONMENTAL ENGINEERING
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 | Modeling sediment erosion is important in a wide range of environmental problems. The effects of various environmental factors on erosion rates have been studied, but the effects of surface slope on erosion rates of a wide range of sediments have not been quantified. The effects of surface slope, both in the direction of flow (pitch) and perpendicular to the flow (roll), on erosion rates of quartz particles were investigated using ... |
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| Perturbation Methods in Stability and Norm Analysis of Spatially Periodic Systems |
16 JAN 2006 |
21 pages |
| Authors:
Makan Fardad; Bassam Bamieh; CALIFORNIA UNIV SANTA BARBARA DEPT OF MECHANICAL AND ENVIRONMENTAL ENGINEERING
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| We consider systems governed by partial differential equations with spatially periodic coefficients over unbounded domains. These spatially periodic systems are considered as perturbations of spatially invariant ones, and we develop perturbation methods to study their stability and H2 system norm. The operator Lyapunov equations characterizing the H2 norm are studied using a special frequency representation, and formulae are given for the perturbation expansion of their solution. The structure of these ... |
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| Improved Performance of MEMS Based Filters |
30 JUN 2005 |
10 pages |
| Authors:
Kimberly L. Turner; Steven W. Shaw; CALIFORNIA UNIV SANTA BARBARA DEPT OF MECHANICAL AND ENVIRONMENTAL ENGINEERING
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| As the demand for wireless communications technology continues to increase, so too does the demand for effective and efficient filters, as these devices, which pass signals with frequency components inside a specific bandwidth while attenuating those outside of it, are often integral components of such technology. Micro-scale components are more desirable than their more conventional counterparts primarily due to their size, low power consumption, and ease of integration with electrical ... |
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| On Stability and the Spectrum Determined Growth Condition for Spatially Periodic Systems |
2005 |
8 pages |
| Authors:
Makan Fardad; Bassam Bamieh; CALIFORNIA UNIV SANTA BARBARA DEPT OF MECHANICAL AND ENVIRONMENTAL ENGINEERING
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| We consider distributed parameter systems where the underlying dynamics are spatially periodic on the real line. We examine the problem of exponential stability, namely whether the semigroup e(At) decays exponentially in time. It is known that for distributed systems the condition that the spectrum of A belongs to the open left-half plane is, in general, not sufficient for exponential stability. Those systems for which this condition is sufficient are said ... |
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| On Optimal Sensor Placement and Motion Coordination for Target Tracking |
2004 |
10 pages |
| Authors:
Sulema Aranda; Sonia Martinez; Francesco Bullo; CALIFORNIA UNIV SANTA BARBARA DEPT OF MECHANICAL AND ENVIRONMENTAL ENGINEERING
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| This work studies optimal sensor placement and motion coordination strategies for mobile sensor networks. For a target tracking application with range sensors, we investigate the determinant of the Cramer-Rao Lower Bound and compute it in the 2D and 3D cases. We characterize the global minima of the 2D case. We propose and characterize motion coordination algorithms that steer the mobile sensor network to an optimal deployment and that are amenable ... |
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| Acquisition of a Nanoindenter for Research on Small-Scale Materials and Structures |
AUG 2003 |
6 pages |
| Authors:
Frank W. Zok; D. R. Clarke; N. C. MacDonald; Kimberly L. Turner; CALIFORNIA UNIV SANTA BARBARA DEPT OF MECHANICAL AND ENVIRONMENTAL ENGINEERING
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| The first project is "Matrix Enabled Damage Tolerance in Oxide Continuous Fiber Reinforced Ceramic Composites", PIs: Frank Zok, Carlos Levi and Robert McMeeking, funded by AFOSR. Here, the nanoindenter is being used for measuring the mechanical properties of fiber-matrix interfaces, through the so- called "fiber push-in" test. In essence, the test involves pushing an individual fiber past the surrounding matrix while simultaneously measuring the sliding displacement at the fiber/matrix interface. ... |
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| Stress Analysis of In-Plane, Shear-Loaded, Adhesively Bonded Composite Joints and Assemblies |
APR 2001 |
36 pages |
| Authors:
Hyonny Kim; Keith Kedward; CALIFORNIA UNIV SANTA BARBARA DEPT OF MECHANICAL AND ENVIRONMENTAL ENGINEERING
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| Recent small aircraft that have been certified in the United States, such as the Cirrus SR2O and the Lancair Columbia 300, share similar structural attributes. Specifically, they are both of nearly all-composite construction and both make extensive use of adhesive bonding as a primary method for forming structural joints. Adhesive bonding has potential for being a simple and cost- effective means by which large built-up structures can be assembled. Challenges ... |
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| Effects of Surface Preparation on Long-Term Durability of Composite Adhesive Bonds |
APR 2001 |
24 pages |
| Authors:
Jason Bardis; Keith Kedward; CALIFORNIA UNIV SANTA BARBARA DEPT OF MECHANICAL AND ENVIRONMENTAL ENGINEERING
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| The long-term effects of surface preparation techniques for composite bonded joints are addressed. Several potential factors are evaluated, concentrating on the effects of peel plies and grit blasting on the fracture toughness and failure mode of adhesively bonded composites. An evaluation of the floating roller peel test configuration is described, where the intent was to extract quantitative data from this commonly used quality control test method. Subsequently, an alternate form ... |
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| Development of Micro-Resolution PIV and Analysis of Microthrusters for Small-Scale Aircraft and Spacecraft |
2000 |
91 pages |
| Authors:
Carl D. Meinhart; CALIFORNIA UNIV SANTA BARBARA DEPT OF MECHANICAL AND ENVIRONMENTAL ENGINEERING
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| This research program consisted of two primary research objectives that were aimed at advancing the current understanding of microfluidic processes related to the development of small-scale aircraft and spacecraft. (1) Develop ultra-high resolution PIV instrumentation for measuring velocity vectors with spatial resolutions approaching one micron and temporal resolutions approaching five nanoseconds for use in measuring microfluidic devices. (2) Analyze and document the flow physics of several micronozzles with diameters ranging ... |
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| Dynamics and Control of Infinite-Dimensional Models of Jet Engine Compression Systems |
20 AUG 1998 |
9 pages |
| Authors:
Igor Mezic; CALIFORNIA UNIV SANTA BARBARA DEPT OF MECHANICAL AND ENVIRONMENTAL ENGINEERING
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| The objective of this project was to study dynamics and control of jet engine compression systems within the new framework that we have developed for the infinite dimensional Moore Greitzer model. In this framework, the Moore Greitzer model of compressor dynamics was reformulated as a set of nonlinear evolution equations (one partial differential equation, and two ordinary differential equations). We designed control laws for the infinite dimensional Moore Greitzer model ... |
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| Characterization of Joint Nonlinear Stiffness and Damping Behavior for Inverse Dynamics of Flexible Articulated Structures |
14 AUG 96 |
10 pages |
| Authors:
Brad Paden; Thomas A. Trautt; CALIFORNIA UNIV SANTA BARBARA DEPT OF MECHANICAL AND ENVIRONMENTAL ENGINEERING
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| An inverse dynamics algorithm is derived for active vibration quenching of structures. The algorithm uses frequency domain techniques to compute an input function needed to produce a desired response at a particular degree of freedom. The desired response is a transition from the initial vibrating condition to a non-vibration condition. The algorithm can also be used to modify the input function to correct for system disturbances while the input function ... |
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Reports by Corporate Author
