In this study, efficient methods for optimal sensor placement (OSP) based on a new geometrical viewpoint for damage detection in structures is presented. The purpose is to minimize the effects of noise on the damage detection process. In the geometrical viewpoint, a sensor location is equivalent to projecting the elliptical noise on to a face of response space which is corresponding to the sens...

Previous works have shown numerically that the response of a “stochastic resonator” is enhanced as a consequence of spatial coupling. Also, similar results have been obtained in a reaction-diffusion model by studying the phenomenon of stochastic resonance (SR) in spatially extended systems using nonequilibrium potential (NEP) techniques. The knowledge of the NEP for such systems allows us to de...

An electric proptdsion vehicle designm! to transport cargo in support of a piloted expedition to Mars will require electrical power in the range of megawatts. This paper summarizes an evaluation of various megawatt-class power processing unit (PPU) design and technology options for high-power nuclear electric propulsion (NEP) vehicles using turboalternators and a d v a n c e d magnetoplasmady n...

This paper presents the analysis, design and implementation of a millimeter-wave W-band power detector. Fabricated in a 0.18-μm SiGe BiCMOS technology, the detector circuit exhibits a responsivity of 91 kV/W, a noise equivalent power of 0.5 pW/Hz, and a noise figure of 29 dB. The power dissipation of the detector is 75 μW. Reasonable agreement between simulations and measurements is obtained. T...

Plasma waves in gated 2-D systems can be used to efficiently detect THz electromagnetic radiation. Solid-state plasma wave-based sensors can be used as detectors in THz imaging systems. An experimental study of the sub-THz response of II-gate strained-Si Schottky-gated MODFETs (Modulation-doped Field-Effect Transistor) was performed. The response of the strained-Si MODFET has been characterized...

A multi-element HgCdTe electron initiated avalanche photodiode (e-APD) array has been developed for space lidar applications. The detector array was fabricated with 4.3-μm cutoff HgCdTe which covered a spectral response from 0.4 to 4.3 μm. We have characterized a 4x4 detector array with 80 μm square elements and an integrated custom cryogenic silicon read-out integrated circuit (ROIC). The devi...

We have built surface micromachined thin-fllm metallized Si_tN-y optical absorbers for transition-edge sensors (TESs) suitable for the Background-Limited far-IR/Submm Spectrograph (BLISS). BLISS is a broadband (38 ;Um-433 jxm ), grating spectrometer consisting of five wavebands each with a modest resolution of R -̂ 1000. Because BLISS requires the effective noise equivalent power (NEP) of the TE...

Observations of the highest redshift clusters provide the longest lever arm in the attempt to evaluate the evolution of their bulk properties. I present the most recent results on galaxy cluster evolution based on data from the ROSAT North Ecliptic Pole survey. At z > 0.3 there is a deficit of clusters with respect to the local universe which is significant at > 4.7σ. The evolution appears to b...