Investigation of 3D semivectorial finite-difference beampropagation method for bent waveguides

A three dimensions of semivectorial finite difference beam propagation method (FD-BPM) in cylindrical coordinates is investigated in order to analyze the optical wave propagation in the bent waveguides with the strong lateral confinement which will keep low radiation loss. The three dimensional (3D) semivectorial wave propagation equation is programmed in the quick and unconditionally stable procedure by using the alternating direction implicit method. This version of FD-BPM could well express the polarization characteristics of modal field near the dielectric interfaces and accurately simulate the wave propagation in bent waveguides even at a very small radius (<100 μm). Moreover, it is pointed out that the numerical precision of the algorithm is intensively affected by the propagation loss of bent waveguides along with the propagation step length of beam propagation method     

Bubble‐based stabilization for the Helmholtz equation

A comparison of two bubble‐enriched methods, derived by different considerations, indicates that the methods are identical in some cases. Thus, series representations of auxiliary functions, derived independently for the two methods, turn out to be equivalent prior to truncation. Three such series for time‐harmonic acoustics are considered. Dispersion analysis points to the more efficient series representation and provides guidelines for the number of terms to be retained. Numerical tests confirm the validity of these practical guidelines. Copyright © 2006 John Wiley & Sons, Ltd.     

Improved bidirectional beam propagation method for analysis ofreflection on nonparallel interfaces

An improved bidirectional beam propagation method (IBBPM) is proposed, to allow the analysis of optical wave reflection and transmission in waveguiding structures with multiple nonparallel interfaces     

Interpersonal models in psychotherapy and counseling: A social-psychological analysis of a clinical problem.

Presented 20 15-17 yr. Old delinquent outpatients in a community mental health center and 20 normal adolescents with potentially imbalanced situations according to F. Heider's (see pa, vol. 33:971) p-o-x model: a perceiver (p), a stimulus person (o), and an event or act (x). Ss' responses support the hypothesis that in potentially imbalanced situations, normal ps would seek balance primarily when the o had or did not have the moral obligation to act, while delinquent ps would seek balance when the o had or lacked the power to act. Change in affect toward the o was the predominant mode of balance seeking in both groups. Heider's model and its implications for psychotherapy and counseling with delinquent adolescents, as well as for psychotherapy in general, are discussed at length. (20 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Development of behaviorally anchored scales for the evaluation of faculty teaching.

Presented a procedure and rationale for evaluating college teaching using behaviorally anchored rating scales. In Stage 1 (n = 38 undergraduates), 9 independent dimensions important for teaching evaluation and representative behavioral incidents were identified. In Stage 2 (n = 54 undergraduates), incidents were allocated to dimensions. In Stage 3 (n = 139 undergraduates), incidents were evaluated on a scale representing effective teaching. Items with low standard deviations were retained for the final scales. The underlying notions of the resulting scales and the advantages of using the behavioral expectation procedure relative to other procedures are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

An Empirical Investigation of a Theoretically Based Measure of Perceived Wellness.

The Perceived Wellness Survey (PWS; T. Adams, 1995; T. Adams, J. Bezner, & M. Steinhardt, 1997) is a recently developed instrument intended to operationalize the comprehensive Perceived Wellness Model (T. Adams, J. Bezner, & M. Steinhardt, 1997), an innovative model that attempts to include the balance of multiple life activities in its evaluation of well-being. Two university samples (N = 317) were used to (a) examine the psychometric properties of the PWS, (b) determine how well the PWS represents the Perceived Wellness Model, and (c) ascertain how well the PWS relates to psychological functioning. Results suggest that the PWS may have potential as a psychometrically sound instrument that does relate in hypothesized ways to standardized measures of mental health. Specifically, a revised 33-item PWS accounted for 29.3% of the variance in Beck Depression Inventory-Second Edition (A. T. Beck, R. A. Steer, & G. K. Brown, 1996) scores, 11.4% of the variance in Beck Anxiety Inventory (A. T. Beck & R. A. Steer, 1993) scores, and 18.2% of the variance in scores on the Hopkins Symptom Checklist-21 (D. E. Green, F. H. Walkey, I. A. McCormick, & A. J. W. Taylor, 1988) when controlling for impression management. Despite this support for the overall PWS, the authors' examination found no psychometric evidence for the existence of separate subscale dimensions, as suggested by the Perceived Wellness Model, the theory upon which the PWS was designed. Implications for these findings are presented. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A bubble‐stabilized finite element method for Dirichlet constraints on embedded interfaces

We examine a bubble‐stabilized finite element method for enforcing Dirichlet constraints on embedded interfaces. By ‘embedded’ we refer to problems of general interest wherein the geometry of the interface is assumed independent of some underlying bulk mesh. As such, the robust imposition of Dirichlet constraints using a Lagrange multiplier field is not trivial. To focus issues, we consider a simple one‐sided problem that is representative of a wide class of evolving‐interface problems. The bulk field is decomposed into coarse and fine scales, giving rise to coarse‐scale and fine‐scale one‐sided sub‐problems. The fine‐scale solution is approximated with bubble functions, permitting static condensation and giving rise to a stabilized form bearing strong analogy with a classical method. Importantly, the method is simple to implement, readily extends to multiple dimensions, obviates the need to specify any free stabilization parameters, and can lead to a symmetric, positive‐definite system of equations. The performance of the method is then examined through several numerical examples. The accuracy of the Lagrange multiplier is compared to results obtained using a local version of the domain integral method. The variational multiscale approach proposed herein is shown to both stabilize the Lagrange multiplier and improve the accuracy of the post‐processed fluxes. Copyright © 2006 John Wiley & Sons, Ltd.     

A direct analytical method to extract mixed‐mode components of strain energy release rates from Irwin's integral using extended finite element method

A new analytical approach, within the extended finite element framework, is proposed to compute mixed‐mode components of strain energy release rates directly from Irwin's integral. Crack tip enrichment functions in extended FEM allow for evaluation of integral quantities in closed form (for some crack configurations studied) and therefore resulting in a simple and accurate method. Several benchmark examples on pure and mixed‐mode problems are studied. In particular, we analyze the effects of high‐order enrichments, mesh refinement, and the integration limits of Irwin's integral. The results indicate that high‐order enrichment functions have significant effect on the convergence, in particular when the integral limits are finite. When the integral limits tend to zero, simpler strain energy release rate expressions are obtained, and high‐order terms vanish. Nonetheless, these terms contribute indirectly via coefficients of first‐order terms. The numerical results show that high accuracy can be achieved with high‐order enrichment terms and mesh refinement. However, the effect of the integral limits remains an open question, with finite integration intervals chosen as h ∕ 2 tending to give more accurate results. Copyright © 2013 John Wiley & Sons, Ltd.     

A High‐order extended finite element method for extraction of mixed‐mode strain energy release rates in arbitrary crack settings based on Irwin's integral

An analytical formulation based on Irwin's integral and combined with the extended finite element method is proposed to extract mixed‐mode components of strain energy release rates in linear elastic fracture mechanics. The proposed formulation extends our previous work to cracks in arbitrary orientations and is therefore suited for crack propagation problems. In essence, the approach employs high‐order enrichment functions and evaluates Irwin's integral in closed form, once the linear system is solved and the algebraic degrees of freedom are determined. Several benchmark examples are investigated including off‐center cracks, inclined cracks, and two crack growth problems. On all these problems, the method is shown to work well, giving accurate results. Moreover, because of its analytical nature, no special post‐processing is required. Thus, we conclude that this method may provide a good and simple alternative to the popular J‐integral method. In addition, it may circumvent some of the limitations of the J‐integral in 3D modeling and in problems involving branching and coalescence of cracks. Copyright © 2013 John Wiley & Sons, Ltd.     

Analysis of an efficient finite element method for embedded interface problems

A stabilized finite element method based on the Nitsche technique for enforcing constraints leads to an efficient computational procedure for embedded interface problems, in which the finite element mesh need not be aligned with the interface geometry. We consider cases in which the jump of a field across the interface is given, as well as cases in which the primary field on the interface is given. Optimal rates of convergence hold. Representative numerical examples demonstrate the effectiveness of the proposed methodology.