A method of limit point calculation in finite element structural analysis

An approach is presented for the calculation of limit points for structures described by discrete coordinates, and whose governing equations derive from finite element concepts. The nonlinear load-displacement path of the imperfect structure is first traced by use of a direct iteration scheme and the determinant of the governing algebraic equations is calculated at each solution point. The limit point is then established by extrapolation and imposition of the condition of zero slope of the plot of load vs. determinant. Three problems are solved in illustration of the approach and in comparison with alternative procedures and test data

A finite element procedure for nonlinear prebuckling and initial postbuckling analysis

A procedure cast in a form appropriate to the finite element method is presented for geometrically nonlinear prebuckling and postbuckling structural analysis, including the identification of snap-through type of buckling. The principal features of this procedure are the use of direct iteration for solution of the nonlinear algebraic equations in the prebuckling range, an interpolation scheme for determination of the initial bifurcation point, a perturbation method in definition of the load-displacement behavior through the postbuckling regime, and extrapolation in determination of the limit point for snap-through buckling. Three numerical examples are presented in illustration of the procedure and in comparison with alternative approaches

Radiative proton-antiproton annihilation and isospin mixing in protonium

A detailed analysis of the radiative $p\bar p$ annihilation is made in the framework of a two-step formalism, the $p\bar p$ annihilates into meson channels containing a vector meson with a subsequent conversion into a photon via the vector dominance model (VDM). Both steps are derived from the underlying quark model. First, branching ratios for radiative protonium annihilation are calculated and compared with data. Then, details of the isospin interference are studied for different models of the initial protonium state and also for different kinematical form factors. The isospin interference is shown to be uniquely connected to the $p\bar p - n\bar n$ mixing in the protonium state. Values of the interference terms directly deduced from data are consistent with theoretical expectations, indicating a dominant $p\bar p$ component for the $^1S_0$ and a sizable $n\bar n$ component for the $^3S_1$ protonium state. The analysis is extended to the $p\bar p \to \gamma \Phi$ transition, where the large observed branching ratio remains unexplained in the VDM approach.Comment: 34 pages, RevTeX, 2 figures, to appear in Phys. Rev. C; typos correcte

A Unified Approach to Convex and Convexified Generalized Differentiation of Nonsmooth Functions and Set-Valued Mappings

In the early 1960's, Moreau and Rockafellar introduced a concept of called \emph{subgradient} for convex functions, initiating the developments of theoretical and applied convex analysis. The needs of going beyond convexity motivated the pioneer works by Clarke considering generalized differentiation theory of Lipschitz continuous functions. Although Clarke generalized differentiation theory is applicable for nonconvex functions, convexity still plays a crucial role in Clarke subdifferential calculus. In the mid 1970's, Mordukhovich developed another generalized differentiation theory for nonconvex functions and set-valued mappings in which the "umbilical cord with convexity" no longer exists. The primary goal of this paper is to present a unified approach and shed new light on convex and Clarke generalized differentiation theories using the concepts and techniques from Mordukhovich's developments

Comparing Ratings: In-class (paper) vs. Out of Class (online) Student Evaluations

Student evaluations of teaching (SET) are used by institutions of higher learning in the tenure and promotion process and in awarding merit pay increases. The trend at some institutions has been towards using an online student assessment instrument (SAI) in lieu of the traditional paper –based, in-class assessment. This study examines the difference in student evaluations in two contexts; online and paper-based, in a finance course taught to non-finance majors. The evidence strongly indicates faculty receives higher evaluations using a paper-based instrument administered during class than with an online assessment instrument which students complete on their own time

Recent advances in the theory of nuclear forces

After a brief historical review, we present recent progress in our understanding of nuclear forces in terms of chiral effective field theory.Comment: 6 pages, 2 figures; talk at International Symposium on Correlations Dynamics in Nuclei, University of Tokyo, Japan, 31 January-4 February, 200

Effects of Biochar Amendment and Arbuscular Mycorrhizal Fungi Inoculation on Availability of Soil Phosphorus and Growth of Maize

A glasshouse experiment was conducted to study the interactive effects of biochar amendment and arbuscular mycorrhizal fungi (AMF) inoculation on phosphorus uptake by maize (Zea mayze L.) grown on a calcareous soil of Kupang, East Nusa Tenggara. The biochar was made of cow dung. Twelve treatment combinations (three biochars levels of 0, 5 and 7.5 g/kg of soil, and four AMF inoculation levels of 0, 5, 10 and 15 spores / kg of soil) were arranged in a completely randomized block design with three replicates. Results of the study showed that at 8 weeks after transplanting, the biochar and mycorrhizal treatments increased the availability soil phosphorus and phosphorus uptake by maize. Application 4.5 and 7.5 g biochar/kg of soil combined with inoculation of 10-15 AMF spores / kg of soil provided to high value of phosphorus uptake by maize. Application of biochar alone, however, did not significantly improve maize growth and phosphorus uptake by maize