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Auerswald J.,Center Suisse Delectronique Et Of Microtechnique | Fecht H.-J.,University of Ulm
Journal of the Electrochemical Society | Year: 2010

Nanocrystalline wear-resistant Ni-W (42 wt % tungsten) layers have been electrodeposited on steel, aluminum, titanium alloys, and silicon wafers. The resulting microstructures and textures were characterized as a function of processing conditions. Measurements of Young's modulus, hardness, coefficient of thermal expansion, internal stress, wear resistance, and thermal stability are presented. Possible applications of the material for wear-resistant coatings or for microsystems technology are outlined. © 2010 The Electrochemical Society.

Meyer S.A.,University of Colorado at Boulder | Meyer S.A.,U.S. National Institute of Standards and Technology | Meyer S.A.,University of Colorado at Denver | Fortier T.M.,U.S. National Institute of Standards and Technology | And 3 more authors.
Applied Physics B: Lasers and Optics | Year: 2013

We present an optically stabilized Yb:KYW fslaser frequency comb. We use an f-2f nonlinear interferometer to measure the carrier envelope offset frequency (f0) and the heterodyne beatnote between the comb and a stable CW laser at 1068 nm to detect fluctuations in the comb repetition rate (frep). Both of these degrees of freedom of the comb are then controlled using phase-locked loops. As a demonstration of the frequency-stabilized comb, we generate low-phase-noise 10 GHz microwaves through detection of the pulse train on a high bandwidth photodiode. The phase noise of the resulting 10 GHz microwaves was -99 dBc/Hz at 1 Hz and the corresponding Allen deviation was<2.6 ×10-15 at 1 s, measured by comparison to an independently stabilized Ti:sapphire frequency comb. This room-temperature, optically based source of microwaves has close-to-carrier phase noise comparable to the very best cryogenic microwave oscillators.

Adler A.,Carleton University | Gaggero P.O.,Center Suisse Delectronique Et Of Microtechnique | Maimaitijiang Y.,Carleton University
Physiological Measurement | Year: 2011

We characterize the ability of electrical impedance tomography (EIT) to distinguish changes in internal conductivity distributions, and analyze it as a function of stimulation and measurement patterns. A distinguishability measure, z, is proposed which is related to the signal-to-noise ratio of a medium and to the probability of detection of conductivity changes in a region of interest. z is a function of the number of electrodes, the EIT stimulation and measurement protocol, the stimulation amplitude, the measurement noise, and the size and location of the contrasts. Using this measure we analyze various choices of stimulation and measurement patterns under the constraint of medical electrical safety limits (maximum current into the body). Analysis is performed for a planar placement of 16 electrodes for simulated 3D tank and chest shapes, and measurements in a saline tank. Results show that the traditional (and still most common) adjacent stimulation and measurement patterns have by far the poorest performance (by 6.9 ×). Good results are obtained for trigonometric patterns and for pair drive and measurement patterns separated by over 90°. Since the possible improvement over adjacent patterns is so large, we present this result as a call to action: adjacent patterns are harmful, and should be abandoned. We recommend using pair drive and measurement patterns separated by one electrode less than 180°. We describe an approach to modify an adjacent pattern EIT system by adjusting electrode placement. © 2011 Institute of Physics and Engineering in Medicine.

Adler A.,Carleton University | Gaggero P.,Center Suisse Delectronique Et Of Microtechnique | Maimaitijiang Y.,Carleton University
Journal of Physics: Conference Series | Year: 2010

In this paper we propose a novel formulation for the distinguishability of conductivity targets in electrical impedance tomography (EIT). It is formulated in terms of a classic hypothesis test to make it directly applicable to experimental configurations. We test to distinguish conductivity distributions σ2 from σ1, from which EIT measurements are obtained with added white Gaussian noise with covariance Σn. In order to distinguish the distributions, we must reject the null hypothesis H0: x̂ = 0, which has a probability based on the z-score: x̄/Σx. This result shows that distinguishability is a product of the impedance change amplitude, the measurement strategy and the inverse of the noise amplitude. This approach is used to explore different current stimulation strategies. © 2010 IOP Publishing Ltd.

Ruffieux D.,Center Suisse Delectronique Et Of Microtechnique | Krummenacher F.,Ecole Polytechnique Federale de Lausanne | Pezous A.,Center Suisse Delectronique Et Of Microtechnique | Spinola-Durante G.,Center Suisse Delectronique Et Of Microtechnique
IEEE Journal of Solid-State Circuits | Year: 2010

This paper presents an ultra-low power generic compensation scheme that is used to implement a real time clock based on an AlN-driven 1 MHz uncompensated silicon resonator achieving 3.2 μW power dissipation at 1 V and ±10 ppm frequency accuracy over a 0-50 °C temperature range. It relies on the combination of fractional division and frequency interpolation for coarse and fine tuning respectively. By proper calibration and application of temperature dependent corrections, any frequency below that of the uncompensated resonator can be generated yielding programmability, resonator fabrication tolerances and temperature drift compensation without requiring a PLL. To minimize the IC area, a dual oscillator temperature measurement concept based on a ring oscillator/resistor thermal sensor was implemented yielding a resolution of 0.04 °C. The IC was fabricated on a 0.18 μm 1P6M CMOS technology. © 2009 IEEE.

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