P-Version two-dimensional curved beam element using piecewise hierarchical approximation for laminated composites

formula omitted] piecewise hierarchical axisymmetric shell element for heat conduction in laminated composites

p-Version axisymmetric shell element for geometrically nonlinear analysis

Three-dimensional curved beam element based on p-Version for dynamics

Finely laminated diatomaceous sediments from the Miocene Monterey Formation, Lompoc, Santa Barbara County, California, record the mutualistic coupling of life processes and environmental evolution at subannual and subseasonal resolution. In this study we present a new classification of lamina and couplet styles based on couplet bimodality, lamina thickness, compositional domination, lamina spacing, and cyclicity. We also describe five distinct lamina types with emphasis on paleoenvironmental settings, paleoecological associations, and biologically mediated sedimentary/taphonomic processes. Detrital laminae, consisting of silt, clay, and robust diatoms, were deposited from continental runoff during rainy seasons. Thin biosiliceous laminae consist of either moderately preserved high-diversity diatom assemblages, or well-preserved monogeneric phytoplankton assemblages. Most thick, continuous diatomaceous laminae are composed of well-preserved monogeneric and monospecific diatom assemblages that likely experienced biologically induced aggregation and rapid sedimentation without grazing. Thick, discontinuous diatomaceous laminae consist of either Thalassiothrix longissima mats or Chaetoceros setae. Mat laminae reflect stratified water conditions and high biomass conditions developed via vertically migrating diatom mats. Setae laminae are problematic to interpret. Macerated biosilica laminae, consisting of closely packed and highly fragmented biosilica from a variety of taxa, reflect intense zooplankton maceration and dissolution of diverse phytoplankton assemblages. Our results illustrate how different lamina types and associations can be used to proxy specific ecological and oceanographic conditions. This study provides a foundation for developing a high-resolution time series of paleoenvironmental variability recorded by biological event strata in hemipelagic sediments.

A meshless computational method based on the local Petrov-Galerkin approach for the analysis of shell structures is presented. A concept of a three dimensional solid, allowing the use of completely 3-D constitutive models, is applied. Discretization is carried out by using both a moving least square approximation and polynomial functions. The exact shell geometry can be described. Thickness locking is eliminated by using a hierachical quadratic approximation over the thickness. The shear locking phenomena in case of thin structures and the sensitivity to rigid body motions are minimized by applying interpolation functions of sufficiently high order. The numerical efficiency of the derived concept is demonstrated by numerical examples.

p-Approximation axisymmetric shell elements for heat conduction in laminated composites

We present a new hierarchical approximation and scheduling approach for applications and tasks with multiple modes on a single processor. Our model allows for a temporal and spatial distribution of the feasibility problem for a variable set of tasks with non-deterministic and fluctuating costs at runtime. In case of overloads an optimal degradation strategy selects one of several application modes or even temporarily deactivates applications. Hence, transient and permanent bottlenecks can be overcome with an optimal system quality, which is dynamically decided. This paper gives the first comprehensive and complete overview of all aspects of our research, including a novel CBS concept to confine entire applications, an evaluation of our system by using a video-on-demand application, an outline for adding further resource dimension, and aspects of our protoype implementation based on RTSJ.

Based on granular space, the hierarchical structure invariance and optimal approximation for proximity data are presented, and four results are obtained as follows. Firstly, an improved algorithm for computing the hierarchical structure and the related min-transitive closure of a fuzzy proximity relation are given, and the properties of key point sequence are studied by introducing the key points and key values of a fuzzy proximity relation. Secondly, two basic concepts, the hierarchical structure invariance and isomorphism of fuzzy proximity relations are introduced, and some examples are given to illustrate that the hierarchical structure of a fuzzy proximity relation is variant under three typical triangular norms. Thirdly, the hierarchical structure invariance theorem of fuzzy proximity relation under a mapping or transformation is given. Finally, for a given fuzzy proximity relation, a mathematical model for obtaining the optimal approximation in order to keep its hierarchical structure is established through the use of the linear combination of its minimum fuzzy proximity relation and min-transitive closure. These results help us understand the hierarchical structures, and provide theories and methodologies for the structural analysis and applications of proximity data.

Objective To explore the feasibility and clinical effects of transforaminal fenestration approach in lumbar spine.Methods Transforaminal fenestration approach was performed on 30 specimens of adult lumbar spine from L1 to S1 segments,with the exiting nerve root and posterior aspect of disc fully exposed.The resected structures were measured.The 3D CT was performed before and after fenestration,and the structure resected was measured.The 3D CT data of lumbar spine of 31 adult patients were collected and the resected structures were measured.Transforaminal fenestration approach was applied in 10 patients with far lateral lumbar disc herniation.Microendoscopic discectomy was performed with mobile endospine system at level of L3,4 in 2 cases,L4,5 in 4,L5S1 in 4.Results From L1 to S1,the isthmus and laminae gradually extends laterally,the transverse process gradually moves downward,and the distance between the dura sac and the lateral edge of lamina and facet increased.At the segment of L1,2,L2,3 and L3,4,only a small range of structure was resected.At the segment of L4,5 and L5S1,a large range of lamina and faceted were resected,and the dura sac can not be fully exposed.A crescentiform fenestration can preserve more connection of isthmus and lower facet.The transforaminal fenestration approach was successfully used in all the 10 patients,the herniation and sequestered nucleus was exposed fully and removed completely.The follow-up time was 12 months,excellent result was obtained in 8 patients,and good in 2 according to Macnab scale,without instability at dynamic film.Conclusion Transforaminal fenestration approach can provide enough exposition with the preservation of stable structure in lumbar spine,especially with endoscopic surgery and cresceutiform fenestration,and far lateral lumbar disc herniation can be effectively treated in this approach. Key words: Lumbar vertebrae; Intervertebral disk displacement; Anatomy; Treatment outcome

Localization of the cell bodies of the fibers of the direct spino-olivary pathways as well as those laying in the dorsal column nuclei and the nucleus cervicalis lateralis as the indirect pathway, have been studied using horseradish peroxidase injected in the inferior olive. The injection sites were both large, involving no less than one third of the antero-posterior extent of the inferior olive, and small, involving less than one third. Labeling of the spinal cord was never found beyond the TI segment even after a seven day survival time. Significant positive reaction was found only in the upper cervical levels contralaterally in the lamina VI and bilaterally in the border regions of laminae VII, VIII and IX. Few marked neurons were found in the contralateral nucleus cervicalis lateralis. More numerous labelled cells were found in the dorsal column nuclei, gracilis and cuneatus. Although positive reactions were observed bilaterally, it was far more important in the contralateral side. The topographical relationship between the dorsal column nuclei and the inferior olive is also described.

Objective To analyze the results of subtotal corpectomy with titanium mesh implantation and pedicle screw fixation by posterior approach for severe thoracic and lumbar fracture.Methods From January 2006 to August 2007, 36 patients with severe thoracic and lumbar fracture were treated.According to AO classification, all patients were A3.According to ASIA, there were 8 cases for grade A, 16 cases for grade B, 8 cases for grade C, 4 cases for grade D.A posterior midline incision was taken for this surgery.The laminae of the injured vertebra and adjacent upper and lower vertebrae as well the facets and screw entry points were exposed.Then pedicle screws were put into the upper and lower vertebrae and a distraction reduction was tried to restore spinal alignment for temporary fixation.The lamina of the injured vertebra and relevant facet joints were resected.And also unilateral or bilateral medial part of pedicle was removed to build a posterolateral working pathway.Through this pathway a subtotal corpectomy was done and a titanium mesh with suitable size was implanted.The titanium mesh was fastened by compressing the pedicle screws after a satisfactory fluoroscopy.The efficacy of treatment was assessed by evaluation of the Cobb angle restoration and reduction of canal compromise.Results All these surgeries were performed successfully without any neurological deterioration.The 36 cases were followed up for 12 to 24 months (18 months on average).Neurological status of all patients improved at least 1 ASIA grade at 12 months postoperatively.35 patients obtained bony fusion.During follow-up, lumbar physical lordosis was reconstructed and no evident correction loss, fusion rate was 97.3%.One patient appeared titanium mesh sink and kyphosis recurrence.Conclusion One-stage combined anteroposterior surgery can be accomplished in a prone position.It was proved to be an effective treatment for severe thoracic and lumbar fracture. Key words: Spinal fractures; Bone screws; Treatment outcome

Recent work has demonstrated that composite finite-elements provide an effective means for physically based modeling of deformable bodies. In this paper we present a number of highly effective improvements of previous work to allow for a high-performance and high-quality simulation of boundary surfaces of deformable bodies with changing topology, for instance, due to cuts and incisions. Starting at a coarse resolution simulation grid, along a cut we perform an adaptive octree refinement of this grid down to a desired resolution and iteratively pull the fine level finite-element equations to the coarse level. In this way, the fine level dynamics can be approximated with a small number of degrees of freedom at the coarse level. By embedding the hierarchical adaptive composite finite-element scheme into a geometric multigrid solver, and by exploiting the fact that during cutting only a small number of cells are modified in each time step, high update rates can be achieved for high resolution surfaces at very good approximation quality. To construct a high quality surface that is accurately aligned with a cut, we employ the dual-contouring approach on the fine resolution level, and we instantly bind the constructed triangle mesh to the coarse grid via geometric constrains.

The dual reciprocity method (DRM) and the radial integration method (RIM) are techniques used in BEM to transform domain integrals into boundary integrals. They are suitable for boundary element formulations where a complete fundamental solution is either unavailable or very complex, because in these cases one or more terms can remain as domain integrals in order to use a simpler fundamental solution. Thus, a large number of problems can be solved with the knowledge of a few number of fundamental solutions and additional terms as inertia or non-linear effects, can be treated as body forces and taken to the boundary. In both methods, the remaining terms are approximated through a finite series expansion involving proposed approximating functions and coefficients to be determined. This expansion is substituted in the generated domain integrals that are, subsequently, tr ansformed into boundary integrals. In this paper, a boundary element formulation for thin shallow shells with no domain discretization is presented. The domain integrals due to the curvature of the shells are tran sformed into boundary integrals using the radial integration method. Two approximation functions are used in this work. The first is the radial ba sis function that has been used extensively in the DRM given by:

A generalization of a NURBS based parametric mesh-free method (NPMM), recently proposed by Shaw and Roy (2008), is considered. A key feature of this parametric formulation is a geometric map that provides a local bijection between the physical domain and a rectangular parametric domain. This enables constructions of shape functions and their derivatives over the parametric domain whilst satisfying polynomial reproduction and interpolation properties over the (non-rectangular) physical domain. Hence the NPMM enables higher-dimensional B-spline based functional approximations over non-rectangular domains even as the NURBS basis functions are constructed via the usual tensor products of their one-dimensional counterparts. Nevertheless the method still lacks the universality that the FEM enjoys. In particular, for many non-simply connected domains, the geometric map may not be locally bijective everywhere and this severely restricts the general applicability of the NPMM. In this paper, a piecewise form of the NPMM is proposed, wherein the domain is decomposed into a collection of simply connected sub-domains or element patches (analogous to the FEM). The NPMM is then employed over each sub-domain without affecting the continuity of approximated functions across inter-sub-domain boundaries. This is quite unlike the usual FEM. The proposed procedure not only possesses the generality of the FEM, it is also equipped with higher order, globally smooth and interpolating basis functions. It may thus be interpreted as a seamless bridge between the FEM and mesh-free methods. In the context of weak implementations of the piecewise NPMM, we propose a conformal knot-grid integration scheme. Finally, we illustrate these schemes for weak numerical solutions of a few linear and nonlinear boundary value problems of engineering interest.

Collection of Solved Nonlinear Problems for Remote Shaping and Patterning of Liquid Structures on Flat and Curved Substrates by Electric and Thermal Fields