Least squares acceleration filtering for the estimation of signalderivatives and sharpness at extrema [and application to biologicalsignals]

A family of finite impulse-response (FIR) filters is derived which estimate the second derivative or "acceleration" of a digitized signal. The acceleration is obtained from parabolas that are continuously fit to the signal using a least squares optimization criterion. A closed-form solution for the filter coefficients is obtained. The general approach is computationally simple, can be performed in real-time, and is robust in the presence of noise. An important application of the method, that of measuring sharpness in biologic signals, is presented using the electroencephalogram (EEG) and electrocardiogram (EKG) signals as examples. Furthermore, the design method is extended to derive FIR filters for estimating derivatives of arbitrary order in digital signals of biologic or other origins.     

The Role of Adsorbed and Subsurface Carbon Species for the Selective Alkyne Hydrogenation Over a Pd-Black Catalyst: An <Emphasis Type="Italic">Operando</Emphasis> Study of Bulk and Surface

The selective hydrogenation of propyne over a Pd-black model catalyst was investigated under operando conditions at 1 bar making use of advanced X-ray diffraction (bulk sensitive) and photo-electron spectroscopy (surface sensitive) techniques. It was found that the population of subsurface species controls the selective catalytic semi-hydrogenation of propyne to propylene due to the formation of surface and near-surface PdC_x that inhibits the participation of more reactive bulk hydrogen in the hydrogenation reaction. However, increasing the partial pressure of hydrogen reduces the population of PdC_x with the concomitant formation of a β-PdH_x phase up to the surface, which is accompanied by a lattice expansion, allowing the participation of more active bulk hydrogen which is responsible for the unselective total alkyne hydrogenation. Therefore, controlling the surface and subsurface catalyst chemistry is crucial to control the selective alkyne semi-hydrogenation.     

Accelerated aging tests of chromium containing amorphous hydrogenated carbon coatings for solar collectors

Chromium containing amorphous hydrogenated carbon films (a-C : H/Cr) have been prepared by simultaneous rf plasma activated chemical vapour deposition of methane and magnetron sputtering of a chromium target. During deposition the substrates were heated (up to 300°C) and DC biased (−200 and −600 V) in order to obtain films with high chemical stability. Constant temperature tests were performed at 250°C in air with coatings deposited on silicon substrates. The degradation of the coatings was monitored by Raman spectroscopy and reflectance and transmission measurements. The main degradation mechanisms are discussed and the relevant parameters which improve the durability of the coatings are presented. Furthermore, the durability of solar selective, multilayered coatings which were deposited on copper sheets was investigated. Based on accelerated aging tests at different temperature loads in air (at 220°C, 250°C and 300°C) and in a humid environment (80°C sample temperature in humid air with 85°C and 95% relative humidity) the service lifetime in a flat plate collector is predicted to amount to more than 25 years.     

Airway obstruction due to arytenoid prolapse in a child

Outcomes of clients with severe mental illness in a psychosocial and vocational rehabilitation program modeled after the Program for Assertive Community Treatment were tracked through record review to determine if clients' employment gains were sustained while they were in the program. A total of 184 clients participated in the program between December 1984 and February 1994, of whom 34 percent remained for one to four years and 33 percent remained for longer than four years. Sixty-four percent of the clients who stayed in the program a year or longer attained employment. The program maintained an average employment rate of 33 percent of all participating clients. More than half of the clients who held jobs worked part time and were employed more than half of the time that they were in the program.     

An Open Environment for Real-Time Applications

This paper describes an open system architecture that allows independently developed hard real-time applications to run together and supports their reconfiguration at run-time. In the open system, each real-time application is executed by a server. At the lower level, the OS scheduler schedules all the servers on the EDF basis. At the upper level, the server scheduler of each server schedules the ready jobs of the application executed by the server according to the algorithm chosen for the application. The paper describes the two-level CPU scheduling scheme used by the open system and the design and implementation of a uniprocessor open system within the framework of the Windows NT operating system. The implementation consists of three key components: the two-level hierarchical kernel scheduler, common system service providers, and real-time application programming interface.