Reactivity of 6-methyl and 4,7-dimethyl indene in cationic polymerization

Summary The reactivity ratios of 6-methyl and 4,7-dimethyl indene were determined with respect to styrene, at various temperatures, and the relative activation parameters calculated and discussed.     

Fuzzy constraints in job-shop scheduling

This paper proposes an extension of the constraint-based approach to job-shop scheduling, that accounts for the flexibility of temporal constraints and the uncertainty of operation durations. The set of solutions to a problem is viewed as a fuzzy set whose membership function reflects preference. This membership function is obtained by an egalitarist aggregation of local constraint-satisfaction levels. Uncertainty is qualitatively described in terms of possibility distributions. The paper formulates a simple mathematical model of job-shop scheduling under preference and uncertainty, relating it to the formal framework of constraint-satisfaction problems in artificial intelligence. A combinatorial search method that solves the problem is outlined, including fuzzy extensions of well-known look-ahead schemes.This paper is partially based on the Ph.D. dissertation of the second author. Preliminary versions have been presented at the IJCAI'93 Workshop on Knowledge-Based Scheduling, Chambéry, France, September 1993, and at the EURO XIII/OR 36 Conference, Glasgow, UK, July 1994.     

Evaluation of a French immersion program: The Ottawa study through Grade five.

Assessed a Canadian French immersion program in which English-speaking pupils attending English schools are taught partially or completely in French. The program involved nearly 33% of the children who entered the Ottawa public school system in kindergarten. The sample included 4 representative classes at each of Grades 3, 4, and 5 from the immersion program and 4 similar classes from the regular English programs. The 2 groups were matched according to socioeconomic status characteristics and were generally from a middle to upper-middle-class background. Ss were administered several measures including the Canadian Cognitive Abilities Test and Canadian Tests of Basic Skills. Only Grade 5 students were given the Metropolitan Science Test only. French immersion pupils were given a set of achievement tests in French and tests of reading comprehension in French. Results indicate that immersion group Ss were in general on the same level with or ahead of the regular English in most academic areas considered (e.g., work-study skills and mathematics) and were performing satisfactorily in French. (French summary) (10 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Grafting of poly(α-chloroacrylonitrile) (α-PCIAN) on carbon black and electrical properties of α-PCIAN-grafted carbon black compositions

The electrical properties of poly(α-chloroacrylonitrile) (PCIAN) carbon black compositions were determined. These materials were prepared by polymerizing α-chloroacrylonitrile in the presence of carbon black (GC resistors). Resistivities measurement of GC resistors shows a semiconductor-like behavior. Moreover, the resistance change of GC resistors with electrical field strength is very large. It is concluded that the conduction of GC resistors is controlled by the thin polymer layer present at the surface of the carbon black particles. Heat degradation of such compositions was also investigated: A significant weight loss above 150°C is observed in all cases which can be attributed to thermal dehydrochlorination of PCIAN. After heat treatment at 300°C, during 1 h, the resistivities decrease of about 1 order of magnitude because of the formation of a semiconducting polyconjugated polymer by dehydrochlorination of PCIAN.     

Optimal matching of convex polygons

We descibe in this paper the problem of matching two series of observations of a 2-D contour, in which each sampling of the contour has different hidden parts. This problem is formulated as the minimization of the distance between the convex hulls of the two sampling and a solution method, based on nonlinear programming techniques, is presented. Computational results are reported to illustrate the practical applicability of the approach.