Search results for "T method"
showing 10 items of 1254 documents
Comparison of two vibrational procedures for the direct determination of mancozeb in agrochemicals.
2007
The direct determination of mancozeb in agrochemicals has been made by diamond attenuated total reflectance (ATR) Fourier transform infrared spectroscopy in the middle range (DATR-MIR) and diffuse reflectance infrared Fourier transform spectroscopy in the near range (DR-NIR) methods using in both cases a previous identification of the samples using a dendrographic classification and an appropriate partial least squares (PLS) calibration established from a set of nine external standards and optimized for each type of sample. It was analyzed a heterogeneous population of 11 samples obtained from the Spanish market, containing different co-formulated products, such as fosetyl-Al, copper oxychl…
Bounding Techniques and Their Application to Simplified Plastic Analysis of Structures
1990
In the framework of the simplified analysis methods for elastoplastic analysis problems, the bounding techniques possess an important role. A class of these techniques, based on the so-called perturbation method, are here presented with reference to finite element discretized structures. A general bounding principle is presented and its applications are illustrated by means of numerical examples.
Prediction of Ductile Fractures Occurrence in Deep Drawing of Square Boxes
1996
Abstract The authors propose a new approach for the prediction of tearing in the deep drawing process of square boxes. Such an approach is based on a damage mechanics formulation and in particular on the yield condition for damaging materials proposed by Tvergaard and Needleman and on a strain controlled nucleation model. The flow rule associated to the yield condition is introduced in a finite element explicit formulation founded on the solution of the dynamic equilibrium equation and on an explicit time integration scheme. By this way the developed model allows to calculate the void volume fraction value during the deep drawing process of square boxes and consequently to predict the insur…
Crack growth in fillet welded steel joints subjected to membrane and bending loading modes
2020
Abstract The present paper presents the results from extensive studies of the fatigue damage evolution in fillet welded steel joints subjected to Constant Amplitude (CA) stress under membrane and bending loading modes. The welded joints in question are F class details (category 71) with plate thicknesses ranging from 25 to 32 mm. The steel quality is a medium strength carbon manganese steel. Crack growth histories for the shallow semi-elliptical shaped cracks emanating from the weld toe are obtained by an Alternating Current Potential Drop (ACPD) technique. These growth histories are presented in detail and modelled by Linear Elastic Facture Mechanics (LEFM). The calculations follow the rec…
Pattern Matching and Pattern Discovery Algorithms for Protein Topologies
2001
We describe algorithms for pattern-matching and pattern-learning in TOPS diagrams (formal descriptions of protein topologies). These problems can be reduced to checking for subgraph isomorphism and finding maximal common subgraphs in a restricted class of ordered graphs. We have developed a subgraph isomorphism algorithm for ordered graphs, which performs well on the given set of data. The maximal common subgraph problem then is solved by repeated subgraph extension and checking for isomorphisms. Despite its apparent inefficiency, this approach yields an algorithm with time complexity proportional to the number of graphs in the input set and is still practical on the given set of data. As a…
Compensation of the impact of low-cost manufacturing techniques in the design of E-plane multiport waveguide junctions
2016
In this work, a full-wave tool for the accurate analysis and design of compensated E-plane multiport junctions is proposed. The implemented tool is capable of evaluating the undesired effects related to the use of low-cost manufacturing techniques, which are mostly due to the introduction of rounded corners in the cross section of the rectangular waveguides of the device. The obtained results show that, although stringent mechanical effects are imposed, it is possible to compensate for the impact of the cited low-cost manufacturing techniques by redesigning the matching elements considered in the original device. Several new designs concerning a great variety of E-plane components (such as …
Virtual element method for computational homogenization of composite and heterogeneous materials
2020
Abstract In this study, a two-dimensional multi-region framework, based on the use of the Virtual Element Method (VEM), is developed for computational materials homogenization and applied to different classes of widely employed heterogeneous materials. The VEM has recently emerged as a powerful generalisation of the Finite Element Method capable of dealing with very general polygonal mesh elements, including non-convex or highly distorted elements. Such features are appealing for the treatment of problems whose analysis domains present complex or statistical morphological features, which would generally require careful and time-consuming mesh/data preparation and regularization. In this wor…
A Fiber Optic Strain Gage Sensor for Measuring Preload in Thick Composite Bolted Joints
2019
Mechanical fastening is a popular choice in joining composites because of the ability to transfer high loads and the ease of assembly and disassembly. In this study, the failure behavior of composite–aluminum single lap bolted joint is investigated. In particular, the effects of varying the preload on the bolt are examined. In order to accurately measure the preload, a specialized sensor that uses a fiber Bragg grating sensor embedded in the bolt is proposed and created. This sensor is realized for the current tests but can be expanded to other applications. An experimental study of bolted single-lap joints varying the tightening torque value has been carried out and, in order to validate t…
Defining a reduced volume zone for the simulation of burst test on a composite pressure vessels
2018
International audience; A Fibre-Break Model (FBM) developed at Mines ParisTech can predict the burst pressure of high pressure composite vessels. This model uses random values of fibre strength at each Gauss point of the considered vessels meshed with finite element (FE). However, previous studies has determined the optimum FEs to be used on real-scale structures (0.1 mm x 0.1 mm x 8 mm). A simple calculation shows that, on a real-scale pressure vessel, this induces a gigantic number of FEs, hence the extensive computation time. To overcome this problem, the integral range method is proposed to find a reduced volume zone of the vessels, on which an equivalent calculation can be made and giv…
A direct impedance tomography algorithm for locating small inhomogeneities
2003
Impedance tomography seeks to recover the electrical conductivity distribution inside a body from measurements of current flows and voltages on its surface. In its most general form impedance tomography is quite ill-posed, but when additional a-priori information is admitted the situation changes dramatically. In this paper we consider the case where the goal is to find a number of small objects (inhomogeneities) inside an otherwise known conductor. Taking advantage of the smallness of the inhomogeneities, we can use asymptotic analysis to design a direct (i.e., non-iterative) reconstruction algorithm for the determination of their locations. The viability of this direct approach is documen…