Some aspects of fatigue crack propagation

Evaluation of fatigue crack propagation models on aluminum plates under load

A study of RSI under combined stresses

The behavior of typical rigidized surface insulation material (RSI) under combined loading states was investigated. In particular, the thermal stress states induced during reentry of the space shuttle were of prime concern. A typical RSI tile was analyzed for reentry thermal stresses under computed thermal gradients for a model of the RSI material. The results of the thermal stress analyses were then used to aid in defining typical combined stress states for the failure analysis of RSI

Cylindrical and spherical shells with cracks

Numerical analysis of meridional crack in cylindrical and spherical shells subjected to internal pressur

An Uqp(u2)U_{qp}(u_2) Rotor Model for Rotational Bands of Superdeformed Nuclei

A nonrigid rotor model is developed from the two-parameter quantum algebra $U_{qp}({\rm u}_2)$. [This model presents the $U_{qp}({\rm u}_2)$ symmetry and shall be referred to as the qp-rotor model.] A rotational energy formula as well as a qp-deformation of E2 reduced transition probabilities are derived. The qp-rotor model is applied (through fitting procedures) to twenty rotational bands of superdeformed nuclei in the $A \sim 130$, 150 and 190 mass regions. Systematic comparisons between the qp-rotor model and the q-rotor model of Raychev, Roussev and Smirnov, on one hand, and a basic three-parameter model, on the other hand, are performed on energy spectra, on dynamical moments of inertia and on B(E2) values. The physical signification of the deformation parameters q and p is discussed.Comment: 24 pages, Latex File, to appear in IJMP

On qpqp-Deformations in Statistical Mechanics of Bosons in D Dimensions

The Bose distribution for a gas of nonrelativistic free bosons is derived in the framework of $qp$-deformed second quantization. Some thermodynamical functions for such a system in D dimensions are derived. Bose-Einstein condensation is discussed in terms of the parameters q and p as well as a parameter $\nu_0'$ which characterizes the representation space of the oscillator algebra.Comment: 15 pages, Latex File, to be published in Symmetry and Structural Properties of Condensed Matter, Eds. T. Lulek, B. Lulek and W. Florek (World Scientific, Singapore, 1997

On an Alternative Parametrization for the Theory of Complex Spectra

The purpose of this letter is threefold : (i) to derive, in the framework of a new parametrization, some compact formulas of energy averages for the electrostatic interaction within an (nl)N configuration, (ii) to describe a new generating function for obtaining the number of states with a given spin angular momentum in an (nl)N configuration, and (iii) to report some apparently new sum rules, actually a by-product of (i), for SU(2) > U(1) coupling coefficients.Comment: Published in Physics Letters A 147, 417-422 (1990

Racism and racial categorization.

Social identity theory predicts that perceivers strongly identified with an in-group will maximize the distinction and maintain a clear boundary between their own and other groups by categorizing others' membership accurately. Two experiments tested the prediction that racially prejudiced individuals, who presumably identify highly with their racial in-group, are more motivated to make accurate racial categorizations than nonprejudiced individuals. Results indicated that prejudiced participants not only took longer to categorize race-ambiguous targets (Experiments 1 and 2), but also made more nonverbal vocalizations when presented with them (Experiment 1), suggesting response hesitation. The results support the hypothesis that, compared to nonprejudiced individuals, prejudiced individuals concern themselves with accurate identification of in-group and out-group members and use caution when making racial categorizations

Initial Transformation of Photo-Viable Free Amino Acids in the Presence of Surrogate and Standard Dissolved Organic Matter Under Sunlit Irradiation

With more than half of the nation’s drinking water affected by wastewater discharge from upstream and more indirect and direct reuse of treated wastewater, human health and ecotoxicological impacts resulting from effluent organic material (EfOM) will increase. Dissolved free amino acids (DFAAs), nitrogen components of EfOM, are essential nitrogen sources for microorganisms and play important roles in global N-cycling in natural aquatic environments. Several DFAAs including histidine, methionine, and tyrosine in sunlit surface waters are susceptible to direct and indirect photochemical transformation with reactive oxygen species. In this study, we investigated the reaction kinetics and initial reaction mechanisms involved in the fate of DFAAs through temperature-dependent bench-top photolysis experiments. Three prevalent surrogate DOM compounds were chosen (1,4-naphthoquinone, umbelliferone, 2-naphthaldehyde) which have been shown to be critical photosensitizers in the natural environment leading to the production of photochemically-produced reactive intermediates (PPRI) such as singlet oxygen (1O¬2), excited triplet state CDOM (3CDOM*), and hydroxyl radicals (HO•). All chosen surrogate DOM compounds and amino acids are structurally unique generating distinct degradation pathways of amino acids at three different temperatures (10 °C, 20 °C, 30 °C)

Sum Rules for Multi-Photon Spectroscopy of Ions in Finite Symmetry

Models describing one- and two-photon transitions for ions in crystalline environments are unified and extended to the case of parity-allowed and parity- forbidden p-photon transitions. The number of independent parameters for characterizing the polarization dependence is shown to depend on an ensemble of properties and rules which combine symmetry considerations and physical models.Comment: 16 pages, Tex fil