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Engineering Models (engineering + models)
Selected AbstractsDetermination of Gradient and Curvature Constrained Optimal PathsCOMPUTER-AIDED CIVIL AND INFRASTRUCTURE ENGINEERING, Issue 1 2006Michael J. De Smith Initially, we examine the case of a single (global) gradient constraint and a planar surface, with or without boundaries and obstacles. This leads to a consideration of surface representation using rectangular lattices and procedures for determining shortest gradient-constrained paths across such surfaces. Gradient-constrained distance transforms are introduced as a new procedure to enable such optimal paths to be computed, and examples are provided for a range of landform profiles and gradients. Horizontal and vertical curvature constraints are then analyzed and incorporated into final solution paths at subsequent stages of the optimization process. Such paths may then be used as preanalyzed input to detailed cost and engineering models to speed up, and where possible improve, the quality and cost-effectiveness of route selection. [source] A Blind Trial Evaluation of a Crime Scene Methodology for Deducing Impact Velocity and Droplet Size from Circular Bloodstains,JOURNAL OF FORENSIC SCIENCES, Issue 1 2007Lee Hulse-Smith M.S. ABSTRACT: In a previous study, mechanical engineering models were utilized to deduce impact velocity and droplet volume of circular bloodstains by measuring stain diameter and counting spines radiating from their outer edge. A blind trial study was subsequently undertaken to evaluate the accuracy of this technique, using an applied, crime scene methodology. Calculations from bloodstains produced on paper, drywall, and wood were used to derive surface-specific equations to predict 39 unknown mock crime scene bloodstains created over a range of impact velocities (2.2,5.7 m/sec) and droplet volumes (12,45 ,L). Strong correlations were found between expected and observed results, with correlation coefficients ranging between 0.83 and 0.99. The 95% confidence limit associated with predictions of impact velocity and droplet volume was calculated for paper (0.28 m/sec, 1.7 ,L), drywall (0.37 m/sec, 1.7 ,L), and wood (0.65 m/sec, 5.2 ,L). [source] An energetic material model for time-dependent ferroelectric behaviour: existence and uniquenessMATHEMATICAL METHODS IN THE APPLIED SCIENCES, Issue 12 2006Alexander Mielke Abstract We discuss rate-independent engineering models for the multi-dimensional behaviour of ferroelectric materials. These models capture the non-linear and hysteretic behaviour of such materials. We show that these models can be formulated in an energetic framework which is based on the elastic and the electric displacements as reversible variables and on interior, irreversible variables like the remanent polarization. We provide quite general conditions on the constitutive laws which guarantee the existence of a solution. Under more restrictive assumptions we are also able to establish uniqueness results. Copyright © 2006 John Wiley & Sons, Ltd. [source] The radial basis functions method for identifying an unknown parameter in a parabolic equation with overspecified dataNUMERICAL METHODS FOR PARTIAL DIFFERENTIAL EQUATIONS, Issue 5 2007Mehdi Dehghan Abstract Parabolic partial differential equations with overspecified data play a crucial role in applied mathematics and engineering, as they appear in various engineering models. In this work, the radial basis functions method is used for finding an unknown parameter p(t) in the inverse linear parabolic partial differential equation ut = uxx + p(t)u + ,, in [0,1] × (0,T], where u is unknown while the initial condition and boundary conditions are given. Also an additional condition ,01k(x)u(x,t)dx = E(t), 0 , t , T, for known functions E(t), k(x), is given as the integral overspecification over the spatial domain. The main approach is using the radial basis functions method. In this technique the exact solution is found without any mesh generation on the domain of the problem. We also discuss on the case that the overspecified condition is in the form ,0s(t)u(x,t)dx = E(t), 0 < t , T, 0 < s(t) < 1, where s and E are known functions. Some illustrative examples are presented to show efficiency of the proposed method. © 2007 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq, 2007 [source] Behavior of Cardiomyocytes and Skeletal Muscle Cells on Different Extracellular Matrix Components,Relevance for Cardiac Tissue EngineeringARTIFICIAL ORGANS, Issue 1 2007Karin Macfelda Abstract:, Myocardial cell transplantation in patients with heart failure is emerging as a potential therapeutic option to augment the function of remaining myocytes. Nevertheless, further investigations on basic issues such as ideal cell type continue to be evaluated. Therefore, the aim of our studies was to compare the performance of skeletal muscle cells and cardiomyocytes with respect to their proliferation rate and viability on different extracellular matrix components (EMCs). Rat cardiomyocytes (RCM) and rat skeletal muscle cells (RSMC) were cultured on EMCs such as collagen type I, type IV, laminin, and fibronectin. The components were used as "single coating" as well as "double coating." Proliferation rates were determined by proliferation assays on days 1, 2, 4, and 8 after inoculation of the cells. The most essential result is that collagen type I enhances the proliferation rate of RSMC but decreases the proliferation of RCM significantly. This effect is independent of the second EMC used for the double-coating studies. Other EMCs also influence cellular behavior, whereas the sequence of the EMCs is essential. Results obtained in our studies reveal the significant different proliferation behavior of RCM and RSMC under identical conditions. As skeletal muscle cells are also used in heart tissue engineering models, these results are essential and should be investigated in further studies to prove the applicability of skeletal muscle cells for heart tissue engineering purposes. [source] Konzepte des Verbundbaus für hohe Stanzlasten , Grundlagen und AnwendungBETON- UND STAHLBETONBAU, Issue 11 2008Michael Fastabend Prof. Dr.-Ing. Die Tragfähigkeit von Flachdecken wird im Wesentlichen durch die Biegeverformungen und Durchstanzwiderstände beschränkt. Vermittels des Einsatzes von Stanzkreuzen auf der Basis von bauaufsichtlichen Zulassungen oder von Ingenieurmodellen des Verbundbaus lassen sich die ertragenen Durchstanzlasten erheblich steigern. Der vorliegende Beitrag beschreibt am Beispiel des Neubaus der Ernst-August-Galerie in Hannover den vorteilhaften Einsatz von Stanzkreuzen des Verbundbaus für höchste Stanzlasten in einer Flachdecke einer Abfangebene. Concepts of Composite Constructions for High Punching Loads , Basic Principles and Application The bearing capacity of flat slabs is largely limited by deformation due to bending and punching resistance. By means of the use of punching shear cruciform head systems on the basis of building authority approval or engineering models of composite constructions, the punching loads can be increased considerably. The article at hand describes the beneficial use of punching shear cruciform head systems of composite constructions for highest punching loads in a flat slab of a transferring level taking the example of the new building of the Ernst-August gallery in Hannover. [source] | |||||||||||||