Twenty-two consecutive children with repaired cleft lip and/or palate [isolated cleft lip (CL) 6, isolated cleft palate (CP) 7, unilateral cleft lip and palate (UCLP) 7, and bilateral cleft lip and palate 2] with a mean age of 27 months underwent spectrographic measures of tape-recorded speech (DSP Sona-Graph digital unit). Controls were 22 age- and sex-matched noncleft children. Data analyzed included (1) the Spanish vocalic variables [a, i, u, e, o]: first formant, second formant, duration, and context; (2) obstruent variables [p, t, k]: burst, voice onset time, and duration, and (3) nasal variables [m]: first formant, second formant, and duration. Statistically significant differences were observed between the CL group and the control group in the first formant of [e] and in the increase of the frequency of the [t] burst. Comparison between UCLP and controls showed differences in the second formant of [a], in the first formant of [o], and in the second formant of [o]. These results suggest a small but significant influence of either the cleft lip or its repair on lip rounding for [o] and [u]. In addition, tongue position differences were most likely responsible for the differences seen with [a] and [e]. Spectrographic differences in the current patients did not contribute to meaningful differences in speech sound development. Individualized care (orthodontics, surgery, speech therapy) in children with cleft lip and/or palate attended at specialized craniofacial units contributes to normalization of speech development.

SUMMARYIn this paper we develop an a posteriori error analysis of a coupling of finite elements and boundary elements for a fluid-structure interaction problem in two and three dimensions. This problem is governed by the acoustic and the elastodynamic equations in time-harmonic vibration. Our methods combine integral equations for the exterior fluid and finite element methods for the elastic structure. It is well-known that due to the reduction of the boundary value problem to boundary integral equations the solution is not unique in general. However, due to superposition of various potentials, we consider a boundary integral equation which is uniquely solvable and which avoids the irregular frequencies of the negative Laplacian operator of the interior domain. In this paper, two stable procedures are considered; one is based on the non-symmetric formulation and the other one is based on a symmetric formulation. For both formulations we derive reliable residual a posteriori error estimates. From the estimators we compute local error indicators which allow us to develop an adaptive mesh refinement strategy. For the two dimensional case we perform an adaptive algorithm on triangles and for the three dimensional case we use hanging nodes on hexahedrons. Numerical experiments underline our theoretical results. Copyright c 2000 John Wiley & Sons, Ltd.key words: Coupling of finite elements and boundary elements, fluid-structure interaction problem, residual a posteriori error estimator, adaptive algorithm.

In this article, we establish a hierarchical a posteriori error estimate for a coupling of finite elements and boundary elements for a fluid‐structure interaction problem posed in two and three dimensions. These methods combine boundary elements for the exterior fluid and finite elements for the elastic structure. We consider two weak formulations, a nonsymmetric one and a symmetric one, which are both uniquely solvable. We present the reliability and efficiency of the error estimates. For the two dimensional case, we compute local error indicators which allow us to develop an adaptive mesh refinement strategy on triangles. For the three dimensional case, we use hexahedrons as elements. Numerical experiments underline our theoretical results. © 2011 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq 2012

We present and analyze an a posteriori error estimator based on mesh refinement for the solution of the hypersingular boundary integral equation governing the Laplacian in three dimensions. The discretization under consideration is a nonconforming domain decomposition method based on the Nitsche technique. Assuming a saturation property, we establish quasireliability and efficiency of the error estimator in comparison with the error in a natural (nonconforming) norm. Numerical experiments with uniform and adaptively refined meshes confirm our theoretical results. © 2013 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq 30: 947–963, 2014

In this article, we conduct an a posteriori error analysis of the two‐dimensional time‐dependent Stokes problem with homogeneous Dirichlet boundary conditions, which can be extended to mixed boundary conditions. We present a full time–space discretization using the discontinuous Galerkin method with polynomials of any degree in time and the ℙ2 − ℙ1 Taylor–Hood finite elements in space, and propose an a posteriori residual‐type error estimator. The upper bounds involve residuals, which are global in space and local in time, and an L2‐error term evaluated on the left‐end point of time step. From the error estimate, we compute local error indicators to develop an adaptive space/time mesh refinement strategy. Numerical experiments verify our theoretical results and the proposed adaptive strategy.