Feedback passivation of switched nonlinear systems using storage-like functions

This paper addresses the issues of passivity and feedback passivation of switched nonlinear systems via multiple storage functions. The concept of storage-like functions for switched systems is presented. A sufficient condition for passivity of switched nonlinear systems is given via multiple storage functions under some switching signal. Then, the result is extended to find conditions under which a switched system is feedback equivalent to a passive switched system. Furthermore, passivity of switched cascade systems is investigated.     

An Analysis of Intermetallic Bonding between a Ring Carrier and an Aluminum Piston Alloy

This paper presents the results of an analysis of the formation of an intermetallic bond between a ring carrier and an aluminum piston alloy. The ring carrier is made of austenitic cast iron (Ni-Resist) to increase the wear resistance of the first ring groove and is applied in highly loaded diesel engines. The most important thing is that the Ni-Resist (ferrous) must be bonded with a non-ferrous piston material during the casting of the piston. A metallographic investigation using an optical microscope in combination with the SEM/EDS analysis of the quality of the intermetallic bonding layer was done. The test results show that if the proper conditions are met, then the preparation of the ring carrier can be made successfully, as can the formation of the metal connection between the two materials of different qualities.     

A mid-value select voter

Hardware redundancy may be used in a variety of manners to achieve fault tolerance. One of the most popular techniques is a triple modular redundancy (TMR) scheme. Such a scheme has also been referred to as masking redundancy because failures those affect only if one of the three modules is masked by the majority of the nonfailed modules. Most of the published works on TMR make one crucial assumption: In fault-free operation the outputs are equal. However it is well known that the output of redundant sensor elements in fault-tolerant data acquisition systems cannot be guaranteed to match even in fault-free operation. They are usually handled by a median-select or similar selection rule, so that redundant voter can pick a common value for processing by the rest of the system. This paper presents a VLSI fault-tolerant voter, with redundancy designed into the internal chip architecture. Instead of three we propose installation of four sensor elements. In order to insure that the voted value represents a correct consensus, we propose a mid-value hardware voting technique thanks to which we solve the problem of dissemination of each sensor element value to other ones. Finally, the effect of fault-tolerance on voter performance is discussed.     

Clock aligner based on delay locked loop with double edge synchronization

In CMOS multistage clock buffer design, the duty-cycle of clock is liable to be changed when the clock passes through several buffer stages. The pulse-width may be changed due to unbalance of the p- and n-OS transistors in the long buffer. This paper describes a delay locked loop with double edge synchronization for use in a clock alignment process. Results of its SPICE simulation, that relate to 1.2 μm CMOS technology, shown that the duty-cycle of the multistage output pulses can be precisely adjusted to (50 ± 1)% within the operating frequency range, from 55 MHz up to 166 MHz.