Lag-windowing and multiple-data-windowing are roughly equivalent for smooth spectrum estimation

There is no fundamental difference between lag-windowing a correlation sequence and multiple-windowing a data sequence when the objective is to reduce the mean-squared error of a spectrum estimator. By analyzing the approximate low-rank factorization of a bandlimiting Toeplitz operator, we find that lag-windowed (or spectrally smoothed) spectrum estimators have multiple-data-windowed implementations. This makes the Blackman-Tukey-Grenander-Rosenblatt spectrogram equivalent to the Thomson spectrum estimator (and vice-versa), meaning BTGR spectrograms may be implemented in a multichannel filterbank version of the Thomson estimator.     

Trivalent passivation of plated zinc and zinc alloys—alternatives to hexavalent based systems

Hexavalent chrome passivates have been used for improving the corrosion resistance of sacrificial zinc and zinc alloy coatings on ferrous substrates for many years now. However, forthcoming legislation and corporate policies are beginning to curtail the use of hexavalent chrome compounds and replacements are actively being sought.

Comparative corrosion resistance data using passivation systems based on trivalent chrome is presented here. This data demonstrates at least the same performance to that obtained by hexavalent systems currently used and also shows that the corrosion resistance of the trivalent chrome free passivates does not significantly diminish after thermal shock treatment. This makes it particularly suitable for components that are subjected to high ambient temperatures. No changes to the dimensional characteristics of the components occur. Recommended application areas include the engine compartment, brake components, fasteners of all sizes and fluid system components.

When used in conjunction with recommended final finishes, these hexavalent chrome-free (Cr6⁺) passivates have the potential to replace more expensive alloy or dip spin type coatings.     

A unified framework for the Sussman, Moyal, and Janssen formulas

This paper derives three fundamental identities in the radar and sonar literature, namely, Sussman' identity for ambiguity functions, Moyal's formula which establishes the value of the inner product between two scattering functions, and Janseen's formula which establishes identities for mixed inner products between waveforms and Gabor wavelets. Starting from the fundamental convolution identity, we derive Sussman's identity. Following from an initial value theorem of Fourier analysis, we obtained Moyal's formula. Following from Poisson's sum formula and an initial value theorem, we also obtained Janssen's equality. The relationship between these three identities is as follows: Janssen's formula is a sampled-data version of Moyal's formula, and both follow from Sussman's identity. In turn, Sussman's identity is a consequence of the fundamental convolution identity.     

Effects of buried layer geometry on characteristics of doublepolysilicon bipolar transistors

Dependences of electrical characteristics of double polysilicon transistors on n⁺ buried islands (subcollector) are examined. By simply modifying layouts of the buried island, the Early voltage (V _A), collector-to-emitter breakdown voltage (BV_CEO), and β×V_A product of transistors are increased from 42, 5.6, and 3070 V to 61, 6.7, and 3820 V, respectively, while the peak cutoff frequency at a V_CE of 1.5 V is decreased from around 21 to 17 GHz. Exploiting these results, it may be feasible to inexpensively integrate transistors with better f _T-BV_CEO and f_T-V_A tradeoffs for analog and power handling characteristics along with transistors optimized for high-speed operation. These results also indicate that the buried island geometry control could be an issue for controlling electrical characteristics for scaled bipolar transistors     

Thickness of diamond-like carbon coatings quantified with Raman spectroscopy

A model is developed for quantifying the thickness of thin coatings and wear scars using Raman spectroscopy. The model, which assumes that both incident and Raman light obey Beer's law, was applied to Raman spectra from a diamond-like carbon (DLC) coating containing Si and O, known as DLN (diamond-like nanocomposite). The coatings ranged in thickness from 10 nm to 2 μm, according to stylus profilometry. Systematic variations in the Raman carbon (G band) and Si (1st order) peak intensities vs. thickness were found. Fits to the model gave an optical mean free path of λ250 nm for DLN. This value is in good agreement with optical absorption coefficient values of other DLC films. Thickness profiles of wear tracks in the coatings determined by the model compared well with depths determined by profilometry.