CO2-shielded arc as a high-intensity heat source

The characteristics of a CO₂-shielded arc are studied to evaluate its potential as a novel heat source for material processing, with lower costs and higher productivity than that of the tungsten–inert gas (TIG) arc. A double-gas-shielded system, using both CO₂ and an inert gas, is employed for the arc torch; this minimizes consumption of the tungsten electrode and gives arc stability equivalent to an argon TIG arc for 1800 s operation. The arc voltage of the CO₂-shielded arc is about 19 V for an arc current of 150 A and an arc gap of 3 mm, which is much higher than the 12 V obtained for an argon TIG arc. The CO₂ constricts the arc, resulting in an increase in the maximum heat flux density at the anode surface by a factor of about 10 relative to the TIG arc. The penetration depth of stainless steel melted by the CO₂-shielded arc is much larger than that for the argon TIG arc. It is concluded that the greater heating power of the CO₂-shielded arc, which is due to the greater arc constriction, in turn a consequence of the greater specific heat of CO₂, should lead to a large increase in material processing productivity.     

A highly simple failure detection method for electrostatic microactuators: application to automatic testing and accelerated lifetime estimation

Reliability and testability are two important factors for the development of batch fabrication of microelectromechanical systems (MEMS) or mixed MEMS/IC applications. In that frame, an easy-to-implement electrical method of detection of failures is presented in this paper, valid for every kind of electrostatic microactuators showing pull-in behavior, with great expectation value in the case of arrayed MEMS. The method relies on the detection of a pull-in current peak at very low frequency. An experimental setup is described and results are shown obtained with prototypes of electrostatic microactuators with parallel capacitances created by deep reactive ion etching on silicon-on-insulator wafers. This method is really suitable for automation and application to on-line testing during mass production and reliability studies. The functional schematic of a test circuitry is proposed for implementation in an industrial tester or for built-in self-test purposes. Then, in order to illustrate the benefits of this method for reliability studies, it is used in conjunction with high voltage testing for accelerated lifetime measurements. A time gain factor of 20 is achieved with above-mentioned test structures.     

ARTeM: a new system for human authentication using finger vein images

Multimedia Tools and Applications - A new system (ARTeM) for human authentication using finger vein images is described here. The developed algorithm combines 1) a fuzzy contrast enhancement...     

The influence of mood on categorization: A cognitive flexibility interpretation.

Three experiments test the hypothesis that positive mood facilitates cognitive flexibility in categorization. Study 1 used a sorting task and found that positive mood subjects in relation to subjects in other mood states, formed fewer (broader) categories when focusing on similarities among exemplars and more (narrower) categories when focusing on differences. Study 2 used a within-subject design and assessed more direct measures of flexibility. Study 2 found that compared with neutral mood subjects, positive mood subjects (a) perceived a greater number of both similarities and differences between items, (b) accessed more distinct types of similarities and differences, and (c) listed more novel and creative similarities and differences. Study 3 demonstrated that these effects occur for both positive (mood-congruent) and neutral stimuli and identified intrinsic interest in the task as a possible mediating factor. The implications of these findings for understanding the effects of mood on cognitive organization and processing are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

An algebraic approach to H∞ output feedback control problems

We derive an output feedback controller which stabilizes a system and satisfies a prescribed H_∞ norm bound of the closed loop transfer function. The proposed design method is available for any system, i.e. there are no restrictions on D₁₂ and D₂₁. This approach utilizes only algebraic operations, thus proofs are simple and clear.     

High-Speed and Compact Quenching Circuit for Single-Photon Avalanche Diodes

In this paper, an innovative active-quenching and recharging circuit for single-photon avalanche diodes is presented. The proposed driver is very fast and extremely compact. It is based on a novel quenching paradigm that heavily reduces dead time, which now is only limited by the sensor rather than the circuit itself. To test speed performance, we designed the circuit with a dielectrically insulated 2-mum technology supplied by ST Microelectronics and carried out postlayout simulations using SPECTRE. Moreover, the functionality of the circuit was also validated with experimental measurements on a medium scale integration (MSI) discrete implementation.