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Hawaii Electric System Reliability

Silva-Monroy, Cesar A.

This report addresses Hawaii electric system reliability issues; greater emphasis is placed on short-term reliability but resource adequacy is reviewed in reference to electric consumers’ views of reliability “worth” and the reserve capacity required to deliver that value. The report begins with a description of the Hawaii electric system to the extent permitted by publicly available data. Electrical engineering literature in the area of electric reliability is researched and briefly reviewed. North American Electric Reliability Corporation standards and measures for generation and transmission are reviewed and identified as to their appropriateness for various portions of the electric grid and for application in Hawaii. Analysis of frequency data supplied by the State of Hawaii Public Utilities Commission is presented together with comparison and contrast of performance of each of the systems for two years, 2010 and 2011. Literature tracing the development of reliability economics is reviewed and referenced. A method is explained for integrating system cost with outage cost to determine the optimal resource adequacy given customers’ views of the value contributed by reliable electric supply. The report concludes with findings and recommendations for reliability in the State of Hawaii.

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TYPE SAND Report YEAR 2012
DOIOSTI

Titanium subhydride potassium perchlorate (TiH1.65/KClO4) burn rates from hybrid closed bomb-strand burner experiments

Cooper, Marcia; Oliver, Michael S.

A hybrid closed bomb-strand burner is used to measure the burning behavior of the titanium subhydride potassium perchlorate pyrotechnic with an equivalent hydrogen concentration of 1.65. This experimental facility allows for simultaneous measurement of the closed bomb pressure rise and pyrotechnic burn rate as detected by electrical break wires over a range of pressures. Strands were formed by pressing the pyrotechnic powders to bulk densities between 60% and 90% theoretical maximum density. The burn rate dependance on initial density and vessel pressure are measured. At all initial strand densities, the burn is observed to transition from conductive to convective burning within the strand. The measured vessel pressure history is further analyzed following the closed bomb analysis methods developed for solid propellants.

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TYPE SAND Report YEAR 2012
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A Stochastic Programming Formulation for Disinfectant Booster Station Placement to Protect Large-Scale Water Distribution Networks

INFORMS Journal on Computing

Klise, Katherine A.; Seth, Arpan; Hackebeil, Gabriel A.; Haxton, Terranna; Murray, Regan; Laird, Carl D.

We introduce a methodology for optimally locating fixed disinfectant booster stations for response to contamination incidents in water distribution networks. In this work a stochastic programming problem considering uncertainty in both the location and time of the contamination incident is formulated, resulting in a large Mixed Integer Linear Programming problem. While the original full-space problem is intractably large, we show a series of reductions that decrease the size of the problem by up to five orders of magnitude and allow solutions of the optimal placement problem for realistically-sized water network models.

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TYPE Journal Article YEAR 2012
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Global revocation for the intersection collision warning safety application

VANET'12 - Proceedings of the 9th ACM International Workshop on VehiculAr Inter-NETworking, Systems, and Applications

Haas, Jason J.

Identifying and removing malicious insiders from a network is a topic of active research. Vehicular ad hoc networks (VANETs) may suffer from insider attacks; that is, an attacker may use authorized vehicles to attack other vehicles. Specifically, attackers may use their vehicles to broadcast specially formed packets that will trigger warnings in target vehicles. This malicious behavior could have a significant detrimental effect on cooperative safety applications (SAs), one of the driving forces behind VANET deployment. We propose modifications to the intersection collision warning (ICW) SA that enable a certificate authority (CA) to be offline and yet to decide to revoke a vehicle's certificates using retransmitted information that cannot repudiated. Our approach differs from previous proposals in that it is SA specific, and it is immune to Sybil attacks. We simulate and measure the resources an attacker requires to attack a vehicle using the ICW SA without our modifications and demonstrate that our additions reduce the false positive rate arising from errors in estimated vehicle dynamics. © 2012 Author.

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TYPE Conference YEAR 2012
OSTIScopus

High speed travelling wave carrier depletion silicon Mach-Zehnder modulator

2012 Optical Interconnects Conference, OIC 2012

DeRose, Christopher T.; Trotter, Douglas C.; Zortman, William A.; Watts, Michael R.

We present the first demonstration of a travelling wave carrier depletion Mach-Zehnder modulator impedance matched to 50 . This device has a bandwidth of 24 GHz and a halfwave voltage length product of 0.7 V-cm, placing it among the best in its class. © 2012 IEEE.

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TYPE Conference YEAR 2012
ScopusOSTI

Single-mode GaN nanowire lasers

Optics Express

Li, Qiming L.; Wright, Jeremy B.; Chow, Weng W.; Luk, Ting S.; Brener, Igal; Lester, Luke F.; Wang, George T.

We demonstrate stable, single-frequency output from single, asfabricated GaN nanowire lasers operating far above lasing threshold. Each laser is a linear, double-facet GaN nanowire functioning as gain medium and optical resonator, fabricated by a top-down technique that exploits a tunable dry etch plus anisotropic wet etch for precise control of the nanowire dimensions and high material gain. A single-mode linewidth of ∼0.12 nm and >18dB side-mode suppression ratio are measured. Numerical simulations indicate that single-mode lasing arises from strong mode competition and narrow gain bandwidth. © 2012 Optical Society of America.

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TYPE Journal Article YEAR 2012
ScopusOSTIDOI

Active wavelength control of silicon microphotonic resonant modulators

2012 Optical Interconnects Conference, OIC 2012

Lentine, Anthony L.; Zortman, W.A.; Trotter, D.C.; Watts, Michael R.

We present simulations and preliminary experimental results of a new method to stabilize the resonant wavelength of an optical resonant modulator using bit error rate measurements from a local receiver to drive an integrated microheater. Optical interconnections have the potential to significantly reduce the power dissipation and greatly increase the aggregate connection bandwidth in high performance multiprocessor digital computers, intra-satellite communications, and data centers. Silicon photonic micro-ring and micro-disk modulators for the transmit side of the links are an active area of research, because of they are compatible with silicon electronics processing and have been demonstrated at data rates above 10 Gb/s and at sub 100fJ/bit switching energies [1-3]. However, a key problem that remains to be solved for these devices is control of their optical wavelength that varies as a function of fabrication tolerances (thicknesses and dimensions) and temperature. In [4], a heater and sensor were integrated with a modulator to stabilize its wavelength, but the method demonstrated suffers the potential drawbacks of aging of the sensor over time and the potential need to pre-calibrate every sensor/modulator. Here, we present a new method of tuning the resonant wavelength of the device to match the incident light's wavelength using independent logic one and logic zero bit errors from a local receiver and simple logic circuitry to drive an integrated micro-heater to adjust the temperature of the device. Simulations of the control loop show it to be robust to the choice of gain, receiver decision threshold, and starting point temperature. Preliminary experimental results using an integrated microresonant heater modulator device [5] operating at 3.125 Gb/s with an FPGA and external reciver driving the control loop show a tuning range of 25C-32C (>2 nm shift). No dithering or calibration is required; the technique is not susceptible to sensor aging, and it can compensate for long-term drift in the characteristics of the modulator. © 2012 IEEE.

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TYPE Conference YEAR 2012
ScopusOSTI

Are we there yet? When to stop a Markov chain while generating random graphs

Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics)

Ray, Jaideep; Pinar, Ali; Comandur, Seshadhri

Markov chains are convenient means of generating realizations of networks with a given (joint or otherwise) degree distribution, since they simply require a procedure for rewiring edges. The major challenge is to find the right number of steps to run such a chain, so that we generate truly independent samples. Theoretical bounds for mixing times of these Markov chains are too large to be practically useful. Practitioners have no useful guide for choosing the length, and tend to pick numbers fairly arbitrarily. We give a principled mathematical argument showing that it suffices for the length to be proportional to the number of desired number of edges. We also prescribe a method for choosing this proportionality constant. We run a series of experiments showing that the distributions of common graph properties converge in this time, providing empirical evidence for our claims. © 2012 Springer-Verlag.

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TYPE Conference YEAR 2012
ScopusOSTI

Brief announcement: Subgraph Isomorphism on a MultiThreaded shared memory architecture

Annual ACM Symposium on Parallelism in Algorithms and Architectures

Leung, Vitus J.; Mclendon, William

Graph algorithms tend to suffer poor performance due to the irregularity of access patterns within general graph data structures, arising from poor data locality, which translates to high memory latency. The result is that advances in high-performance solutions for graph algorithms are most likely to come through advances in both architectures and algorithms. Specialized MMT shared memory machines offer a potentially transformative environment in which to approach the problem. Here, we explore the challenges of implementing Subgraph Isomorphism (SI) algorithms based on the Ullmann and VF2 algorithms in the Cray XMT environment, where issues of memory contention, scheduling, and compiler parallelizability must be optimized. Copyright is held by the author/owner(s).

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TYPE Conference YEAR 2012
OSTIScopus

Converting a slip table random vibration test to a fixed base modal analysis

Conference Proceedings of the Society for Experimental Mechanics Series

Zwink, Brandon; Mayes, Randall L.; Kelton, David W.; Heister, Jack; Hunter, Patrick; Gomez, Anthony J.

Validation of finite element models using experimental data with unknown boundary conditions proves to be a significant obstacle. For this reason, the boundary conditions of an experiment are often limited to simple approximations such as free or mass loaded. This restriction means that vibration testing and modal analysis testing have typically required separate tests since vibration testing is often conducted on a shaker table with unknown boundary conditions. If modal parameters can be estimated while the test object is attached to a shaker table, it could eliminate the need for a separate modal test and result in a significant time and cost savings. This research focuses on a method to extract fixed base modal parameters for model validation from driven base experimental data. The feasibility of this method was studied on an Unholtz-Dickie T4000 shaker and slip table using a mock payload and compared with results from traditional modal analysis testing methods. © The Society for Experimental Mechanics, Inc. 2012.

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TYPE Conference YEAR 2012
OSTIScopus

Self-improving algorithms for coordinate-wise maxima

Proceedings of the Annual Symposium on Computational Geometry

Clarkson, Kenneth L.; Mulzer, Wolfgang; Seshadhri, C.

Computing the coordinate-wise maxima of a planar point set is a classic and well-studied problem in computational geometry. We give an algorithm for this problem in the self-improving setting. We have n (unknown) independent distributions D 1, D 2,⋯, D n of planar points. An input pointset (p1,p2,⋯,pn) is generated by taking an independent sample pi from each Di, so the input distribution D is the product Π i D i. A self-improving algorithm repeatedly gets input sets from the distribution D (which is a priori unknown) and tries to optimize its running time for D. Our algorithm uses the first few inputs to learn salient features of the distribution, and then becomes an optimal algorithm for distribution D. Let OPTD denote the expected depth of an optimal linear comparison tree computing the maxima for distribution D. Our algorithm eventually has an expected running time of O(OPT D + n), even though it did not know D to begin with. Our result requires new tools to understand linear comparison trees for computing maxima. We show how to convert general linear comparison trees to very restricted versions, which can then be related to the running time of our algorithm. An interesting feature of our algorithm is an interleaved search, where the algorithm tries to determine the likeliest point to be maximal with minimal computation. This allows the running time to be truly optimal for the distribution D. Copyright © 2012 ACM.

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TYPE Conference YEAR 2012
ScopusOSTI

Theory and design of a MEMS-enabled diffraction limited adaptive optical zoom system

Proceedings of SPIE - The International Society for Optical Engineering

Jungwirth, Matthew E.L.; Wick, David V.; Dereniak, Eustace L.

Micro-electro-mechanical systems (MEMS) deformable mirrors are known for their ability to correct optical aberrations, particularly when the wavefront is expanded via Zernike polynomials. This capability is combined with adaptive optical zoom to enable diffraction limited performance over broad spectral and zoom ranges. Adaptive optical zoom (AOZ) alters system magnification via variable focal length elements instead of axial translation found in traditional zoom designs. AOZ systems are simulated using an efficient approach to optical design, in which existing theories for telescope objective design and third-order aberration determination are modified to accommodate the additional degrees of freedom found with AOZ. An AOZ system with a 2.7x zoom ratio and 100mm entrance pupil diameter is presented to demonstrate the validity and capability of the theory. © 2012 SPIE.

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TYPE Conference YEAR 2012
ScopusOSTI

Microsystems: Technology enabler

Proceedings of SPIE - The International Society for Optical Engineering

Okandan, Murat

Microelectronics and microsystems have been part of the key technologies that enabled the incredible pace of development we have seen over the last five to six decades. This paper presents a basic view in terms of technology development supporting new approaches to generation and transfer of knowledge for critical activities, one of the key ones being the ability to capture, store and more efficiently use energy. © 2012 SPIE.

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TYPE Conference YEAR 2012
OSTIOSTIScopusScopus
Results 64201–64400 of 101,000
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