Viscosity of Porous Glasses

Viscosity of porous glasses has been derived from the elastic stress analysis, using the viscous analogy. Viscosity as a function of porosity has been estimated for spherical as well as for arbitrary pore geometry. Since the pore geometry changes during sintering, a shape factor that varies with pore geometry has been considered to predict the viscosity–porosity relationship. Viscosity as a function of porosity was measured on cordierite-type glass by isothermal sinter-forging experiments and data showed good agreement with the analysis. Experimental data from literature on viscosity as a function of porosity on two other glasses also show good agreement with the analysis.     

Oriented crystallization in fiber formation: Inferences from the structure and properties of melt spun syndiotactic polypropylene filaments

In processes, such as melt spinning, the crystallization behavior of syndiotactic polypropylene (sPP) is found to be substantially different from that of most other linear polymers. The anisotropic stress field in such processes leads invariably to extension as well as alignment (orientation) of the chains in the melt, both of which contribute usually to dramatic enhancement in the rate of crystallization. However, since the primary structure of the sPP chain in its most preferred crystal form is comprised of a “coiled helical,” ? (T₂G₂)₂? , sequence, stress‐induced chain extension can lead to conformational sequences that are not favorable for crystallization in this form. As a consequence, process conditions that generate higher stress levels can cause a diminution in the rate of crystallization of this polymer. Such conformation‐related aspects of oriented crystallization of sPP have been addressed through an analysis of the structure and properties of melt‐spun fibers, produced over a range of spinning speeds. The results serve to identify a refinement that is needed in current models of oriented crystallization and also a mechanism to promote the nucleation of crystallization of sPP. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 2305–2317, 2001     

TRAVOS: Trust and Reputation in the Context of Inaccurate Information Sources

In many dynamic open systems, agents have to interact with one another to achieve their goals. Here, agents may be self-interested, and when trusted to perform an action for another, may betray that trust by not performing the action as required. In addition, due to the size of such systems, agents will often interact with other agents with which they have little or no past experience. There is therefore a need to develop a model of trust and reputation that will ensure good interactions among software agents in large scale open systems. Against this background, we have developed TRAVOS (Trust and Reputation model for Agent-based Virtual OrganisationS) which models an agent’s trust in an interaction partner. Specifically, trust is calculated using probability theory taking account of past interactions between agents, and when there is a lack of personal experience between agents, the model draws upon reputation information gathered from third parties. In this latter case, we pay particular attention to handling the possibility that reputation information may be inaccurate.     

AN ENERGY ANALYSIS OF BELT POLISHING PROCESS AND ITS APPLICATIONS TO TIME CYCLE AND TRACKING EFFECTS

Belt polishing is a fine machining process widely used to improve surface texture and to increase wear resistance and fatigue life. Despite the basics of this manufacturing process are not yet well understood, the cycle-time and the belt oscillations frequency are considered as fundamental process variables. In this article, their effects on the surface characterization and on the form aspects are investigated in connection with the principal physical mechanisms activated during the superfinishing operations (cutting, ploughing and sliding). With this aim, an energy approach of the belt polishing process, coupled with SEM observations of the abrasive belt, is introduced. Two belt polishing energetic regimes are identified and then discussed.     

Synthesis and characterization of hindered‐phenol‐containing amine moieties as antioxidants for polypropylene copolymers

(4‐Ethylphenyl)‐3,5‐ditertiarybutyl‐4‐hydroxybenzylamine, 1‐phenyl‐4‐(3,5‐ditertiarybutyl‐4‐hydroxybenzyl)piperazine, and 1‐(3,5‐ditertiarybutyl‐4‐hydroxybenzyl)piperidine were synthesized and characterized, and their performance in polypropylene copolymer (PPCP) was tested by multiple extrusions in a Brabender plasticorder. The thermooxidative stability of PPCP was assessed by the measurement of oxidative induction time at 200 ± 1°C, and the thermal stability was assessed by observation of the change in the melt flow rate. A comparative study of the synthesized antioxidants with the commercially available antioxidant 2,6‐ditertiarybutyl‐4‐methylphenol was made. The presence of phenolic and amino groups influenced the performance of the antioxidants. The performance of the antioxidants influenced the thermal stability of the PPCP. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 1097–1103, 2004     

The epidemiological indices of multiple myeloma and concomitant nephropathies

The authors have conducted an epidemiological study for multiple myeloma morbidity and mortality among 80,000 patients of the Medical Center examined in 1988-1995. Myeloma was diagnosed in 65 cases. Standard incidence rate was 4.09, 3.18 and 3.5 per 100,000 for myeloma in males, females and both sexes, respectively. Standard mortality was 2.76 and 1.73 per 100,000 for males and females, respectively. The above rates do not differ much from those of other countries. In terminal myeloma renal insufficiency occurred in 39 of 41 cases. In 8 cases chronic pyelonephritis was an independent course of renal failure thus indicating the importance of its persistent treatment.     

EROS: a program for quick evaluation of energy recovery systems

the program EROS (Energy Recovery Optimization System) is a flow-sheeting package for evaluating and optimizing the performance of simple networks of heat exchangers. As a flowsheeting system it represents a prototype for what a really convenient system might be. Using EROS one can set up an arbitrary structure of heat-exchangers, stream splitters and mixers. Stream flow rates and entry and exit temperatures may be specified, free, or bounded above and/or below. Phase changes may be allowed to occur. Requiring no more user input (such as initial guesses), the program gathers together the modeling equations and appropriate inequality constraints. It then develops solution procedures repeatedly in the course of optimizing, initially to locate a feasible point and in the final stages to take advantage of tight inequality constraints to reduce the degrees of freedom.     

Factors influencing intention to donate via social network site (SNS): From Asian’s perspective

This study examined whether external factors, which are charity project, charity organization, Internet technology features and social network site (SNS) features influence people’s general attitude towards online donation and their intention to donate via SNS. An online survey was conducted based on the framework of factors influencing the intention to donate via SNS that was adapted from the literature review. Data from 258 respondents were used for analysis. Structural equation modelling was used to test the research model and hypotheses. The results indicated that the Internet technology features factor significantly contributes in influencing people’s general attitude towards online donation, and general attitude positively influences people’s intention to donate via SNSs. The full mediation effect of the general attitude towards online donation on the relationship between Internet technology features and intention to donate via SNS was found. However, charity project, charity organization, and SNS features were not significant factors in influencing people’s intention to donate via SNSs. The sample was limited to some Asian countries (preliminary Malaysia and South Korea). Thus, the results cannot be generalized to other countries. The findings suggest that non-profit organizations should focus on how to deal with the Internet issues, especially pertaining to security and privacy. Therefore, a mechanism for gaining donors’ trust to use the Internet, particularly in doing online transaction must be considered.