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Linear Segments (linear + segment)
Selected AbstractsA unified formulation of the piecewise exact method for inelastic seismic demand analysis including the P -delta effectEARTHQUAKE ENGINEERING AND STRUCTURAL DYNAMICS, Issue 6 2003M. N. Ayd Abstract The non-linear analysis of single-degree-of-freedom (SDOF) systems provides the essential background information for both strength-based design and displacement-based evaluation/design methodologies through the development of the inelastic response spectra. The recursive solution procedure called the piecewise exact method, which is efficiently used for the response analysis of linear SDOF systems, is re-formulated in this paper in a unified format to analyse the non-linear SDOF systems with multi-linear hysteresis models. The unified formulation is also capable of handling the P-delta effect, which generally involves the negative post-yield stiffness of the hysteresis loops. The attractiveness of the method lies in the fact that it provides the exact solution when the loading time history is composed of piecewise linear segments, a condition that is perfectly satisfied for the earthquake excitation. Based on simple recursive relationships given for positive, negative and zero effective stiffnesses, the unified form of the piecewise exact method proves to be an extremely powerful and probably the best tool for the SDOF inelastic time-history and response spectrum analysis including the P-delta effect. A number of examples are presented to demonstrate the implementation of the method. Copyright © 2003 John Wiley & Sons, Ltd. [source] Palaeointensity and palaeodirectional studies of early Riphaean dyke complexes in the Lake Ladoga region (Northwestern Russia)GEOPHYSICAL JOURNAL INTERNATIONAL, Issue 2 2008V. V. Shcherbakova SUMMARY Results of palaeointensity and palaeomagnetic studies for the volcanic rocks of 1450 Ma, from Early Riphaean Baltic shield dyke complex sampled in Lake Ladoga region (Karelia, Northwestern Russia) are reported. Electron microscope observations, thermomagnetic and hysteresis measurements indicate the presence of single domain (SD) to pseudo-single domain (PSD) titanomagnetite (TM) with low Ti content as the main magnetic mineral. Stepwise alternating field (AF) and/or thermal demagnetization revealed a two-component natural remanent magnetization (NRM) for most of the samples. The characteristic remanent magnetization (ChRM) component was isolated between 440 and 590 °C. Note that the ChRM amounts to 95 per cent of the NRM intensity. The geographic position of the ChRM palaeopoles does not contradict the ,key poles' of the [1270; 1580] Myr time interval, testifying anticlockwise rotation of whole East Europe Craton between 1450 and 1500 Ma. Palaeointensity determinations were performed by Coe-modified Thellier procedure. 35 samples passed our palaeointensity selection criteria and show large linear segments on Arai-Nagata plots. The site mean virtual dipole moment (VDM) varies from 2.00 to 3.91 (× 1022 A m2). Based on these and other observations, we suggest that the Palaeo- and MezoProterozoic was dominated by low VDMs. [source] An imprint and merge algorithm incorporating geometric tolerances for conformal meshing of misaligned assembliesINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, Issue 14 2004David R. White Abstract A size tolerant algorithm for imprinting and merging adjacent part geometries is presented in this paper. This approach cleans up misaligned and dirty assembly geometry that is intended for conformal mesh generation. The algorithm first discretizes the boundary edges of adjacent faces into linear segments. The segments are then intersected and a partial intersection graph is calculated from the intersection results. The intersections are calculated by accounting for size tolerances to minimize the effect of misaligned parts on the meshing process. The partial intersection graph is next used to imprint the adjacent faces as appropriate. The imprints are generated using virtual geometry so that the tolerant topology created therein can be employed. Several examples are given to demonstrate the resulting improvement in the mesh quality of conformal meshes. The approach is shown to work robustly with misaligned and poorly defined parts. Copyright © 2004 John Wiley & Sons, Ltd. [source] Guaranteed-quality triangular mesh generation for domains with curved boundariesINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, Issue 10 2002Charles Boivin Guaranteed-quality unstructured meshing algorithms facilitate the development of automatic meshing tools. However, these algorithms require domains discretized using a set of linear segments, leading to numerical errors in domains with curved boundaries. We introduce an extension of Ruppert's Delaunay refinement algorithm to two-dimensional domains with curved boundaries and prove that the same quality bounds apply with curved boundaries as with straight boundaries. We provide implementation details for two-dimensional boundary patches such as lines, circular arcs, cubic parametric curves, and interpolated splines. We present guaranteed-quality triangular meshes generated with curved boundaries, and propose solutions to some problems associated with the use of curved boundaries. Copyright © 2002 John Wiley & Sons, Ltd. [source] Selection of locations of knots for linear splines in random regression test-day modelsJOURNAL OF ANIMAL BREEDING AND GENETICS, Issue 2 2010J. Jamrozik Summary Using spline functions (segmented polynomials) in regression models requires the knowledge of the location of the knots. Knots are the points at which independent linear segments are connected. Optimal positions of knots for linear splines of different orders were determined in this study for different scenarios, using existing estimates of covariance functions and an optimization algorithm. The traits considered were test-day milk, fat and protein yields, and somatic cell score (SCS) in the first three lactations of Canadian Holsteins. Two ranges of days in milk (from 5 to 305 and from 5 to 365) were taken into account. In addition, four different populations of Holstein cows, from Australia, Canada, Italy and New Zealand, were examined with respect to first lactation (305 days) milk only. The estimates of genetic and permanent environmental covariance functions were based on single- and multiple-trait test-day models, with Legendre polynomials of order 4 as random regressions. A differential evolution algorithm was applied to find the best location of knots for splines of orders 4 to 7 and the criterion for optimization was the goodness-of-fit of the spline covariance function. Results indicated that the optimal position of knots for linear splines differed between genetic and permanent environmental effects, as well as between traits and lactations. Different populations also exhibited different patterns of optimal knot locations. With linear splines, different positions of knots should therefore be used for different effects and traits in random regression test-day models when analysing milk production traits. [source] Synthesis and receptor binding of IgG1 peptides derived from the IgG Fc regionJOURNAL OF MOLECULAR RECOGNITION, Issue 2 2004Katalin Uray Abstract The IgG binding Fc, receptors (Fc,Rs) play a key role in defence against pathogens by linking humoral and cell-mediated immune responses. Impaired expression and/or function of Fc,R may result in the development of pathological autoimmunity. Considering the functions of Fc,Rs, they are potential target molecules for drug design to aim at developing novel anti-inflammatory and immunomodulatory therapies. Previous data mostly obtained by X-ray analysis of ligand,receptor complexes indicate the profound role of the CH2 domain in binding to various Fc,Rs. Our aim was to localize linear segments, which are able to bind and also to modulate the function of the low affinity Fc,Rs, like Fc,RIIb and Fc,RIIIa. To this end a set of overlapping octapeptides was prepared corresponding to the 231,298 sequence of IgG1 CH2 domain and tested for binding to human recombinant soluble Fc,RIIb. Based on these results, a second group of peptides was synthesized and their binding properties to recombinant soluble Fc,RIIb, as well as to Fc,Rs expressed on the cell surface, was investigated. Here we report that peptide representing the Arg255,Ser267 sequence of IgG1 is implicated in the binding to Fc,RIIb. In addition we found that peptides corresponding to the Arg255,Ser267, Lys288,Ser298 or Pro230,Val240 when presented in a multimeric form conjugated to branched chain polypeptide in uniformly oriented copies induced the release of TNF,, a pro-inflammatory cytokine from MonoMac monocyte cell line. These findings indicate that these conjugated peptides are able to cluster the activating Fc,Rs, and mediate Fc,R dependent function. Peptide Arg255,Ser267 can also be considered as a lead for further functional studies. Copyright © 2004 John Wiley & Sons, Ltd. [source] | ||||||||||