Showing papers by "University of Notre Dame published in 1973"

The effects of wake splitter plates on the flow past a circular cylinder in the range 10 4 < R <5×10 4

Abstract: Experiments were carried out using models having L/D [les ] 2 and the resulting pressure distributions and vortex shedding characteristics are presented. A simple visualization technique which provides explanations of some of the measured results is described. It is concluded that splitter planes reduce the drag markedly by stabilizing the separation points and produce a wake narrower than that for a plain cylinder, raise the base pressure by as much as 50% and affect the Strouhal number to a lesser degree. Careful measurement techniques have enabled these effects to be presented accurately.

Process for preparing aromatic polyimides, polyimides prepared thereby

Abstract: A process for preparing substantially completely cyclized aromatic polyimides, either monomeric, oligomeric or polymeric, is provided. The process involved the reaction of a mixture of at least one tetracarboxylic acid dianhydride and at least one aromatic diamine in at least one aromatic phenol, preferably cresols, in the presence of an organic azeotroping agent such as a cyclic hydrocarbon, preferably benzene, until substantially all of the water of reaction is eliminated. Other monomers, e.g., a monoamine or an α,β-carboxylic acid monoanhydride can be added to the mixture so as to provide reactive end groups, preferably olefinically terminated, which will enable the polyimide to cure by coupling together by addition or condensation thereby increasing molecular weight with little or no by-product. After the water is removed, it is preferred that the azeotroping agent be removed and then the polyimide increased in molecular weight by heating in the aromatic phenol. The polymer can then be isolated by concentration or precipitation as a powder, or the polymer in solution can be used to prepare coatings on various substrates.

Process for chain-extending unsaturated terminated polyimides and products prepared therefrom

Abstract: Aromatic polyimides with reactive end groups are cured by coupling together by addition or condensation to increase molecular weight with little or no by-product formation. These polyimides can be shaped and formed prior to the coupling. The aromatic polyimides appropriate for coupling are formed by the reaction of an aromatic dianhydride and an aromatic diamine in ratios to provide the appropriate end groups, or by including in the reaction mixture a compound which will provide reactive end groups, e.g., aromatic nitrile, allyl, propargyl, styryl, etc. Depending on the reactive end groups present, coupling of the polyimide is carried out either by self-coupling or by reacting the polyimide with a complementary organic compound. Included in the latter is the reaction with an aromatic bisdipole compound which will propagate the polymer chain.

Some correlates of attitudes towards old people.

Abstract: A group of 103 undergraduate students responded to a semantic differential measure of the attitude toward old men, and to a number of measures assessing potential correlates of this attitude. Attempts were also made to assess the validity of an indirect measure of the attitude toward elderly. Older men were evaluated less positively; they were judged less decisive, and instrumental as compared with younger men. Of all the variables studied only two were significantly related to attitudes toward older men, i.e., socioeconomic status of parents and frequency of contact with elderly. The outcomes with regard to the validity of the indirect measure of attitudes were ambiguous at best.

Annular Truncated Plug Nozzle Flowfield and Base Pressure Characteristics

Abstract: The flowfield and base pressure characteristics of an internal-external-expansion, truncated plug nozzle are described over the pressure ratio range from "open" wake to "closed" wake conditions. The effect of plug length on these characteristics, including the process of wake "closure" is also presented. An existing method for calculating the flowfield and base pressure, for closed wake operation, is modified to include the internal shock wave generated near the shroud exit. The supersonic portion of the flow is calculated using rotational axisymmetric method of characteristics. The technique of Hartree is employed so that the downstream characteristic point locations can be chosen to fit the developing flowfield. An overexpansion technique is used to detect the internal shock wave in the vicinity of the shroud exit so that its effect on the plug base pressure could be determined. Good agreement between the analytical results and experimental data is obtained for closed wake operations.

Chemical and autoflocculation of microorganisms in biological wastewater treatment.

Abstract: Experimental evidence is presented which indicates that both chemical and autoflocculation of microorganisms occur by the same mechanism. Basically, long chain polymeric species attach themselves between the microbial particles and agglomerate them into flocculant particles of sufficient magnitude to subside from suspension under quiescent conditions. Properties of the polymers which are produced during autoflocculation are investigated and these polymers are shown to be capable of causing the agglutination of inorganic colloids such as alumina. It is hypothesized that these biologically generated flocculating polymers could belong to a class of compounds known as transport enzymes. The experimental data qualitatively agrees with this hypothesis.

Chloroplasts and algae as symbionts in molluscs.

Abstract: Publisher Summary This chapter describes chloroplasts and algae as symbionts in molluscs. It discusses recent experimental work on symbiotic chloroplasts and examines the potentialities for future investigations. The symbionts are of three types: Zoochlorellae (Chlorophyceae, Chlorococcales); Zooxanthellae (Dinophyceae, Peridiniales); and free chloroplasts (derived from several plant orders). The chapter deals only with chloroplasts and Zooxanthellae as they represent instances of a close and sustained association, and one in which the symbiont is virtually always intracellular. The chapter also describes the symbiosis of mollusks and Zooxanthellae . A comparison of the morphology of symbiotic plastids with the morphology of plastids from algae upon which the host is thought to feed suggests that some host species, in particular the eqlysioids , harbor morphologically normal and intact plastids, while other hosts possess morphologically atypical plastids. Physiological and biochemical evidence supports this interpretation.

Laboratory Skill Training and Student Teacher Classroom Performance.

Abstract: The assumption that laboratory skill training has a direct influence on classroom performance was tested for a sample of social studies student teachers. Experimental group Ss received six weeks of microteaching training and their teaching performance was compared with that of control Ss in student teaching classrooms. Difference in classroom performance as measured by a low-inference coding system were not significant. Re sults are discussed in terms of possible interaction effects between laboratory training and student teaching.

Social Identities in Anglo and Latin Adolescents

Abstract: Social identities, conceptualized as self-designations and measured by the TST, were examined for samples of high school adolescents in three societies: the United States, Puerto Rico, and Mexico Four identities were explored in terms of salience, frequency, and valence: gender, religion, family, and peer For both males and females in Latin and Anglo cultures gender emerged as the most prominent identity Religious IDs were more frequent for Catholic adolescents The strongest cultural difference was found with respect to negative religious IDs: these were significantly more frequent for Anglo adolescents Positive gender and family IDs were more frequent for Latin adolescents, while peer IDs were slightly more common self-designations for Anglos These tendencies were generally in the expected direction Social and cultural differences between these Anglo and Latin societies were considered as explanations for variations in adolescent identity structures The concept of identity, as used by social psychologists of a sociological bent, refers to the locatioin of an individual in social space (Goffman, 1959; Stone, 1962; Strauss, 1959) This social space consists of the myriad of statuses and roles which a society provides to its members Their selective internalization and integration form the structure of a person's self-concept As Stone (1962:93) pointed out, identity establishes what and where the person is in social terms: "When one has identity, he is situated-that is, cast in the shape of a social object by the acknowledgment of his participation or memberships in social relations" Similarly, Kuhn and McPartland (1954) viewed the self-concept as deriving its consistency and structure from social affiliations From this perspective, a person may (and usually does) have many identities depending on the diversity of social relations in which he engages Some identities are more important than others depending on the degree to which an individual is committed to them; the amount of the "self" that is encompassed by them; and the number of social situations in which they are relevant The structure of the self can be viewed as the hierarchical organization of a person's identities (cf Gordon, 1968; Kuhn and McPartland, 1954; McCall and Simmons, 1966) Identity conceptualized in these terms is more accurately termed social identity, to distinguish it from personal identity (see McCall and Simmons, 1966; Sarbin, 1970, for this distinction) Social identities are derived from a person's group memberships and roles They are expressed through broad social categories such as occupation, sex, religion, family, etc Personal identity, on the other hand, typically refers to self-definitions in terms of unique characteristics' This is similar to Kuhn and McPartland's (1954) distinction between consensual and subconsensual identities * This research was supported by NSF Grant GS 2650; a Woodrow Wilson Dissertation Fellowship; and by Project 1743, Department of Rural Sociology, College of Agriculture, Washington State University as scientific paper No 3905, Washington Agricultural Experiment Station 1 Another usage of the concept of identity as a personal experience is exemplified in the work of Erik Erikson Erikson (1956:60) views identity as a highly subjective, personal experience which the individual develops about who he is He discusses its expression in at least four distinct ways: "At one time it will appear to refer to a conscious sense of individual identity; at another, to an unconscious striving for a continuity of personal character; at a third, as a criterion for the silent doings of ego synthesis; and finally, as maintenance of an inner solidarity with a group's ideals and identity"

Theories of elastic slender curved rods

Abstract: The linear and nonlinear theories of elastic slender curved rods are formulated in a systematic manner. Equations of equilibrium for stress resultants and moments are derived. The generalized strains are defined based on the principle of virtual work. Constitutive equations corresponding to small strains are obtained. The field equations for finite deformations of curved rods can be simplified in the case of small axial strain and moderately small rotations. Further simplifications can be made for the case of slightly curved rods. Two examples are presented to illustrate applications of the developed theories.