A two-chip accelerometer system for automotive applications

A two-chip accelerometer system has been designed, manufactured, and assembled in a standard dual-in-line plastic package. A capacitive sensing element is built on one chip and signal processing circuitry on a separate chip. The sensing element is designed in the form of a differential capacitor pair made from three highly doped polysilicon layers using surface micromachining technology. The circuitry is fabricated using a 1.75 m CMOS technology and includes amplification, EPROM trim, filtering, and self-test functions. The system is designed for 50 g full scale acceleration, and operates in an open loop mode.     

Synthesis and rheological study of some maleic acid and fumaric acid stereoregular polyesters

Summary First unsaturated polyester fibers were prepared starting from stereoregular, macromolecular poly(octamethylene fumarate). Fibers obtained from octamethylene copolyesters of fumaric and terephthalic acids manifested improved mechanical properties and higher melting points. All unsaturated polyester fibers prepared in the study, based on the homopolymer and on copolymers of fumaric acid, even those containing as low as 10% of fumaric acid residues, are able to be covalently bonded to an unsaturated polyester matrix.For part 7, see Jaovi M.S., et al., Makromol. Chem. (submitted)     

H.L. Van Trees (ed.) and K.L. Bell (ed.), Bayesian Bounds for parameter estimation and nonlinear filtering/tracking, Wiley & Sons Ltd, 2007 [Book review]

Parameter and random-process estimation play a central role in signal processing. A common requirement in the estimation problems is to predict and/or evaluate the error performance. This task is often complicated because the system and measurement models are typically non-linear with some inherent uncertainty. The error performance prediction is supposed to be theoretical - its goal is to establish the best achievable limit and is to be carried out even before one develops a suitable estimator. The error performance evaluation is usually done by Monte Carlo simulations once a candidate estimator has been built. Evaluation serves to assess the estimator quality by comparing its actual error with the theoretical prediction. The fundamental question in algorithm design is "Can we do better?" In this context, it is of paramount importance to find a theoretical bound on the error performance and compare it against the performance of various sub-optimal candidate estimators.     

Analysis of nonisothermal sintering of zinc-titanate ceramics doped with MgO

The aim of this work is to analyze nonisothermal sintering of zinc titanate ceramics doped with MgO obtained by mechanical activation. Mixtures of ZnO, TiO₂, and MgO (0, 1.25, and 2.5%) are mechanically activated for 15 min in a planetary ball mill. Nonisothermal sintering is performed in air for 120 min at 800, 900, 1000, and 1100 °C. Microstructure parameters are revealed from an approximation method. Structural characterization of ZnO-TiO₂-MgO system after milling is performed at room temperature using XRPD measurements. The main conclusions are that mechanical activation leads to the particle size reduction, the increase of dislocation density, and lattice strain. Doped zinc titanate samples achieve higher densities after sintering and the diffusion mechanism is dominant during the sintering process. Published in Poroshkovaya Metallurgiya, Vol. 47, No. 1–2 (459), pp. 83–90, 2008.     

Rheological properties of partially hydrolyzed ethylene–vinyl acetate copolymers

Studies have been made of steady-shear and dynamic viscosities for melts of two ethylene–vinyl acetate copolymers and their partially hydrolyzed derivatives using a Weissenberg rheogoniometer over the temperature range of 123–150°C with some tests at 160°C. The flow activation energy of all samples studied was essentially independent of shear stress. The introduction of hydroxyl groups in controlled concentrations, however, produced a complicated flow behavior. At low concentrations, there is a marked increase in Newtonian viscosity, flow activation energy, and shear dependence of viscosity. In contrast to previous reports, a further increase in all three functions was not observed with increasing vinyl alcohol concentration. Dynamic viscosities, in contrast, show monotonic increases with increasing hydroxyl group content, as do activation energies derived from the temperature dependence of the dynamic viscosity. These data may result from an increased chain cohesion due to hydrogen bonding of hydroxyl groups.     

Effectiveness of lubricant additives for copper‐alloy‐steel sliding contacts

A selection of additives and their performance and compatibility with a variety of copper alloys have been evaluated in an SRV test set‐up. The tests show a remarkable variation of tribological behaviour with a clear relation to both the type of lubricant / additive and the type of alloy. One ester‐based additive showed outstanding friction and wear reduction for some groups of copper alloys. In order to better understand the fundamental mechanisms, we applied a variety of surface analyses, such as 3D confocal white light microscopy, scanning electron microscopy and X‐ray photoelectron microscopy. Copyright © 2010 John Wiley & Sons, Ltd.     

Modeling the noise figure of an acousto-optic receiver

By defining the processing gain of an acousto-optic receiver as the ratio of the signal-to-noise ratio at the output of the detector to the signal-to-noise ratio of the intermediate-frequency input, one can model a noise figure for the acousto-optic receiver. The noise figure has a minimum of 0 dB and depends on the ratio of the noise power (internal to the acousto-optic cell) to the intermediate-frequency input noise power multiplied by the frequency and the spatially dependent exponential factor.     

Sintering of mechanically activated Zno-TiO2 powders

Zinc oxide and titanium dioxide powders mixed in an equimolar ratio are mechanically activated in a planetary ball mill and sintered under nonisothermal and isothermal conditions. Nonisothermal sintering is studied using dilatometry and SEM. The activation energy of sintering is determined using the method based on different heating rates and Dorn’s method as well. The phase composition of the isothermally sintered samples is determined using x-ray powder diffraction. Published in Poroshkovaya Metallurgiya, Vol. 47, No. 1–2 (459), pp. 55–62, 2008.