On Routh-Pade model reduction of interval systems

This paper discusses another generalization of the direct Routh table truncation method for interval systems. It is shown that the existing generalization of the direct Routh table truncation fails to produce a stable system, in contradiction to the equivalent result for fixed-coefficients systems. The present method guarantees a stable reduced order model for interval systems as well.     

Model reduction of uncertain FIR discrete-time systems

Model reduction of high-order polynomial systems is considered. The main novelty of the paper is that the polynomial coefficients are assumed to be known only within given intervals. The resulted reduced system is characterized by a fixed-coefficients polynomial. First, the meaning of such a model reduction is defined. Then, applying a novel approach, the maximal "distance" (error) between the polygon in the complex plane which represents, at each frequency, the original uncertain system and the point which represents the resulted reduced-order fixed-coefficients system, is minimized. By a smart definition of this "distance" and by a formulation of the "closest" distance to the polygon as a "maximum" in some sense, the problem is formulated as linear semi-infinite programming with linear constraints, thus reducing significantly the computational complexity. A numerical example is provided.     

Modeling and computer simulation of ultrasonic/sonic driller/corer (USDC)

Simulation and analytical models for the ultrasonic/sonic drill/corer (USDC) are described in this paper. The USDC was developed as a tool for in-situ rock sampling and analysis in support of the NASA planetary exploration program. The USDC uses a novel drive mechanism, which transfers ultrasonic vibrations of a piezoelectric actuator into larger oscillations of a free-flying mass (free-mass). The free-mass impact on the drill bit creates a stress pulse at the drill tip/rock interface causing fracture in the rock. The main parts of the device (transducer, free-mass, bit, and rock) and the interactions between them were analyzed and numerically modeled to explore the drive mechanism. Each of these interactions is normally described by a time-dependent 2- or 3-D model involving slowly converging solutions, which makes the conventional approach unsuitable for USDC optimization studies. A simplified integrated model using tabulated data was developed to simulate the operation of the USDC on desktop PC and successfully predicted the characteristics of the device under a variety of conditions. The simulated results of the model and the experimental data used to verify the model are presented.     

Ensuring Uniform Distribution of the Gas Flow in the Active Section of EGAV1-22-15-7-4 Electrostatic Precipitator

Chemical and Petroleum Engineering - The analysis of industrial operation of EGAV1-22-15-7-4 precipitators, designed for cleaning non-aggressive non-explosive process gases and aspiration air from...     

Pneumatosis intestinalis and portal vein gas after blunt abdominal trauma

The authors report on a 2-year-old boy in whom pneumatosis intestinalis (PI) and portal vein gas (PVG) resulted from blunt abdominal trauma after child abuse. The presumed pathophysiology of PI and PVG is mechanical in this setting. Its presence establishes mucosal injury but does not necessarily imply intestinal necrosis.     

Author's reply [to comments on 'On Routh-Pade model reduction of interval systems']

The paper is reply to the article by Shih-Feng Yang (see ibid., p.273-4, 2005). Previously (Dolgin and Zeheb, 2003), it was shown that the existing generalization of the direct Routh table truncation method for interval systems fails to produce a stable system. Additionally, it was shown how to extend the method to ensure the stability of the resulting interval system. Although the main statement of Dolgin and Zeheb (2003) is correct, there is, however, an omission in the proposed algorithm of building interval Routh table:the newly calculated line in the table may be inconsistent with the last existing line. Two additional conditions should be formulated to avoid this situation. The main idea is to shrink the uncertainty of the elements of the last existing line of the table, in the procedure of building the new line.     

Study of the Influence of Annular Plate Size on the Stress-Strain State of a Vertical Steel Tank

Chemical and Petroleum Engineering - Stress-strain states (SSS) of vertical steel tanks are described along with a method for calculating their strength using CAD technology that takes into account...     

Lasting effects of short-term training on preschoolers’ street-crossing behavior

Can short-term training improve preschoolers’ knowledge of road-crossing concepts as well as behavior in a real traffic situation? Forty children, aged four to five years, were assigned to one of four conditions (game, story, song, and control). Each condition participated in four 15-min classroom-based lessons over four weeks. Two assessments measuring knowledge of street-crossing concepts and one assessment measuring behavior on a real street were used to evaluate performance at baseline and one week and six months post-training. Children in all three experimental conditions showed a significant improvement over the control on the two conceptual assessments. Only children in the game condition significantly improved their behavior on the street-crossing assessment. Furthermore, children in all three experimental conditions retained the same levels of improvement at the six-month follow-up. These results demonstrate that one hour of training can create lasting improvements on preschool children's conceptual knowledge of traffic safety and road-crossing behavior on a real street.     

Disclosure between college students and their siblings.

Two hundred twelve undergraduates reported their disclosure to 1 of their siblings by completing a 31 -topic disclosure questionnaire. Respondents indicated whether they disclosed about each topic, their depth of disclosure, and their motivations for disclosure. Analyses indicate that individuals disclose about fewer topics and do so in less depth to siblings more than 5 years younger than themselves but that there are no differences in disclosure rates or depth to siblings of other ages. Neither participant nor sibling gender significantly affected disclosure rates. Younger siblings reported more disclosure in order to seek advice and emotional support than did older siblings; conversely, older siblings reported more disclosure aimed at teaching younger siblings. Venting was most commonly directed at siblings close in age to oneself. Sisters more often reported disclosing to siblings for the purpose of seeking emotional support than did brothers. (PsycINFO Database Record (c) 2010 APA, all rights reserved)