Search results for "complexity"
showing 10 items of 1094 documents
Influence of oxygen vacancies on the photorefractive effect in barium titanate single crystals
1990
Abstract In this work the influence of the vacancies concentration in pure BaTiO3 single crystals is studied. It is shown that the oxidation and the reduction do not change the electrooptic coefficients. The reduction modifies the nature of the majority carriers. An evaluation of the trap density N is done.
Polarographische Untersuchungen an monomeren und polymeren N-Chlorcarbonamiden
1979
The polarographic reduction of low molecular and high molecular N-chlorocarboxamides at the dropping mercury electrode proceeds in two one-electron-transfer steps, which are highly irreversible. In the case of the low molecular models 1 and 2 the reaction is diffusion-controlled, whereas in the case of the poly(N-chloroamide) 3 the reaction is adsorption-controlled. Reduction of several poly(N-chloroamide)s shows always two reduction waves with a distance of 0,5 V. There is, however, no relation between the polyamide-type and the position of the half-wave potentials. The polarographic reduction can be used as an analytical method for quantitative determination of N-chlorocarboxamide groups …
ChemInform Abstract: The Reduction of α,β-Unsaturated Nitriles and α- Halonitriles with Sodium Hydrogen Telluride.
2010
Abstract Sodium hydrogen telluride reacts chemoselectively with α,β-unsaturated nitriles and α-halonitriles linked to aromatic and aliphatic substituents to give the corresponding saturated nitriles with good yields.
Applications and numerical convergence of the partial inverse method
2006
In 1983, J.E. Spingarn introduced what he called the Partial Inverse Method in the framework of Mathematical Programming. Since his initial articles, numerous applications have been given in various fields including Lagrangian multipliers methods, location theory, convex feasibility problems, analysis of data, economic equilibrium problems. In a first part of this paper we give a survey of these applications. Then by means of optimization problems relevant to location theory such as single and multifacility minimisum or minimax location problems, we examine the main advantages of the algorithm and we point out its drawbacks mainly concerning the rate of convergence. We study how different p…
A Constrained Optimal Model Predictive Control for Mono Inverter Dual Parallel PMSM Drives
2018
The actual trends in the design of AC drives are directed to the reduction of the total weight, volume and cost. Usually, this implies the necessity to adopt new motor topologies and converter architectures. An important role is played by the mono-inverter dual parallel motor (MIDP), which gives the possibility to reduce the total weight and costs of power converters. This paper proposes a novel model predictive control algorithm in order to improve the transient performances of a MIDP used for an overhead carrier. The effectiveness of the proposal control is verified through some numerical simulations.
Flanking regions determine the structure of the poly-glutamine homo- repeat in huntingtin through mechanisms common among glutamine-rich human protei…
2020
International audience; The causative agent of Huntington's disease, the poly-Q homo-repeat in the N-terminal region of huntingtin (httex1), is flanked by a 17-residue-long fragment (N17) and a proline-rich region (PRR), which promote and inhibit the aggregation propensity of the protein, respectively, by poorly understood mechanisms. Based on experimental data obtained from site-specifically labeled NMR samples, we derived an ensemble model of httex1 that identified both flanking regions as opposing poly-Q secondary structure promoters. While N17 triggers helicity through a promiscuous hydrogen bond network involving the side chains of the first glutamines in the poly-Q tract, the PRR prom…
Rapid and Standardized Quantitation of Hemolytic Activity of the Fourth Component of Human Complement
1990
Based on a method that uses the fourth component of complement (C4)-deficient guinea pig serum to quantify the hemolytic activity of C4, we developed an assay that allows the processing of a large number of individual samples with high reproducibility. In contrast to the conventional procedure using titration curves of each sample to be determined, we can show that a single appropriate dilution of the sample allows accurate quantitation of hemolytic activity. The reliability of the procedure is demonstrated using either C4A- or C4B- deficient and normal individual samples.
Panel — Assessing Critical Social Theory Research in Information Systems
1997
The Critical Social Theory (CST) program of information systems research is now just over a decade old. Although the number of researchers associated with the CST program are few, they have had a disproportionately larger impact on the field than other research communities. The main reason for this disproportionate impact can be found in the intense and incisive radical critiques of the foundational assumptions of our field that CST researchers have conducted. These radical critiques have helped to open up the theoretical debate on IS research and point out new directions for future inquiry. But as we turn the century, new challenges are emerging. New information technologies (IT) are rapid…
Structural and Dynamical Complexities of Risk and Catastrophe Systems: an Approach by System Dynamics Modelling
2009
Risk and catastrophe are complex systems. Within the scope of this paper, we focus our attention on structural and dynamic complexities of catastrophes and on the possibility of modelling and simulating its double complexity with a formal and methodological framework: the General Systems Theory and System Dynamics modelling. Then we briefly propose a model of urban catastrophe related to a flood. After we propose some ways of research allowing exceeding the limits related to the modelling.
Rotation-Invariant Texture Retrieval via Signature Alignment Based on Steerable Sub-Gaussian Modeling
2008
This paper addresses the construction of a novel efficient rotation-invariant texture retrieval method that is based on the alignment in angle of signatures obtained via a steerable sub-Gaussian model. In our proposed scheme, we first construct a steerable multivariate sub-Gaussian model, where the fractional lower-order moments of a given image are associated with those of its rotated versions. The feature extraction step consists of estimating the so-called covariations between the orientation subbands of the corresponding steerable pyramid at the same or at adjacent decomposition levels and building an appropriate signature that can be rotated directly without the need of rotating the im…