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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
DOIOSTI

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
DOIOSTI

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
Results 62601–62700 of 99,299
Results 62601–62700 of 99,299