Influence of Temperature Gradients on Sintering: Experimental Tests of a Theory

The H₂O-catalyzed sintering of MgO in temperature gradients between 1303 and 1233 K is compared to sintering of isothermal samples. Both the changes in sample dimensions in planes normal to the temperature gradients and the increases in density for a fixed sintering time are greater than predicted on the assumption that densification in a temperature gradient is a function only of each local temperature in the gradient. Under the conditions used, neither vapor transport nor transport through a liquid phase is important. The results, therefore, support a recent prediction that temperature gradients supplement surface energy changes in driving sintering and related processes not only by vapor transport, as expected from earlier studies, but also by a surface, grainboundary, or bulk diffusion path.     

Production scheduling in a steelmaking-continuous casting plant

In this paper we describe an optimization procedure for planning the production of steel ingots in a steelmaking-continuous casting plant. The strict requirements of the production process defeated most of the earlier approaches to steelmaking-continuous casting production scheduling, mainly due to the lack of information in the optimization models. Our formulation of the problem is based on the alternative graph, which is a generalization of the disjunctive graph of Roy and Sussman. The alternative graph formulation allow us to describe in detail all the constraints that are relevant for the scheduling problem. We then solve the problem by using a beam search procedure, and compare our results with a lower bound of the optimal solutions and with the actual performance obtained in the plant. Computational experience shows the effectiveness of this approach.     

Determination of the phase transition behavior of thermoplastic polyurethanes from coupled rheology/DSC measurements

The rich behavior of thermoplastic polyurethanes (TPUs) undergoing phase transition is investigated by means of combined rheological and DSC techniques. In particular, the kinetics of micro‐phase transition of a commercial TPU are followed under both isothermal conditions (crystallization from the melt), and constant temperature rate heating ramps (melting). In rheological tests, the time evolution of the storage modulus is monitored by using a strain rate–controlled rheometer. The rheological results are compared with those obtained by more traditional calorimetric techniques (DSC) under the same thermal histories. It is shown that rheological measurements can give additional (and, in some cases, more accurate) information than that obtained from the more classical thermal analysis. Polym. Eng. Sci. 44:1514–1521, 2004. © 2004 Society of Plastics Engineers.     

Micromechatronics in medicine

Micromechatronic systems integrate miniature precision mechanisms, actuators, sensors, and embedded control. They are suitable for application in the medical field particularly when miniaturization, reliability, and intimate interaction with the human body are required. Medical applications not only motivate the miniaturization of mechatronic systems, but also encourage the development of novel concepts and technologies for the integration of artificial and biological components into "hybrid" micromechatronic systems, thus giving origin to a new and intriguing field of research and application known as "biomechatronics". Micromechatronic devices can be exploited for acute intervention or for permanent (short- and long-term) implant in the human body. This paper presents many examples of both types of devices being developed in our laboratory, and discusses their associated open problems. Application fields include sensory substitution, internal organs substitution, neural prosthetics, and minimally invasive surgery. Most of the projects are performed in collaboration with other European research groups and industries and supported by programs by the European Union. The conclusion of our analysis is that medical applications of micromechatronics may have tremendous impact on the quality of medical care and may become a very attractive industrial market, provided that some critical technical problems are addressed and solved.     

Apparent shear viscosity of native egg white

Temperature and shear dependency of the apparent viscosity of the thick and thin portions of egg white from fresh hen eggs, in their native state was investigated. The viscosity of the egg white was determined in the temperature range of 5–30°C and the shear rate range 34–600 sec^-1. The viscosity of both the thick and thin portions of the egg white decreased with increase in temperature. The thin portion showed no decrease in viscosity with shearing time at constant shear rates while the viscosity of the thick portion decreased within the first 6 min of shearing and then remained constant. The rate of decrease in viscosity with shearing time was more at higher temperatures. At 20°C and a shear rate of 34.2 sec^-1, the equilibrium-apparent viscosity of the thick portion was 160 cp, approximately forty times greater than that of the thin portion (4cp). This difference in viscometric properties may be due to the presence, in the thick portion, of high molecular weight complexes which are disrupted under shearing.     

Primate cognition and the bared-teeth display: A reevaluation of the concept of formal dominance.

The cognitive implications of the phenomenon of dominance in nonhuman primates and other animals have been poorly addressed. This article shows that the concept of formal dominance currently used in the primatological literature is inherently dependent on the assumption that primates are capable of attribution of knowledge to other individuals. Although this assumption has never been made explicitly, without it the concept of formal dominance is virtually indistinguishable from other, more traditional views of dominance. Recent studies have failed to demonstrate attribution of knowledge in nonhuman primates, thus questioning the validity of formal dominance. The concept of formal dominance was originally proposed to account for a discrepancy between dominance hierarchies based on aggressive behavior and dominance hierarchies based on submissive signals. This article shows that such a discrepancy can be accounted for without invoking complex cognitive processes such as attribution of knowledge. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Multi-perspective Navigation of Movies

Digital libraries of video are rapidly growing in size and availability through digital networks of computers. The explosion of digital unstructure information, such as video, traveling through the network raises the need for tools that allow video information structuring and “intelligent” access to sequences.In this paper we present a novel video database system, which has been expressly designed to support structured storage of movies. A semiotic formalization for movie logical organization is here introduced and exploited to derive the conceptual schema of an object-oriented movie database. This structure is expressly tailored to enable queries on film technical features and on semantic contents as well, thus allowing feature fusion and access from multiple perspectives. A novel visual interaction scheme is implemented that allows users to formulate queries as filtering operations, that enable focussing on the interesting part of information, while skipping the rest. Formalization of the operators of “perspective” and “filtering” is thereby supplied. Retrieval of stored sequences by iconic motion example is also implemented for accessing sequences by contents. Examples are supplied of interaction with the database and of expressive power of visual query language.