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Hierarchical Architecture (hierarchical + architecture)

Distribution by Scientific Domains

Polymers and Materials Science	42%
Engineering	28%
Chemistry	28%

Selected Abstracts

A Multiscale Description of the Electronic Transport within the Hierarchical Architecture of a Composite Electrode for Lithium Batteries

ADVANCED FUNCTIONAL MATERIALS, Issue 17 2009
Jean-Claude Badot
Abstract The broadband dielectric spectroscopy technique is applied, for the first time, to a composite material used as an electrode for lithium battery. The electrical properties (permittivity and conductivity) are measured from low (a few Hz) to microwave (a few GHz) frequencies. The results demonstrate that the broadband dielectric spectroscopy technique is very sensitive to the different scales of the electrode architecture involved in electronic transport, from interatomic distances to macroscopic sizes, as well as to the morphology at these scales, coarse or fine distribution of the constituents. This work opens up new prospects for a more fundamental understanding and more rational optimization of the electronic transport in composite electrodes for lithium batteries and other electrochemical energy storage technologies (including other batteries, supercapacitors, low- and medium-temperature fuel cells), electrochemical sensors and conductor,insulator composite materials. [source]

Fuzzy torque distribution control for a parallel hybrid vehicle

EXPERT SYSTEMS, Issue 1 2002
Jong-Seob Won
A fuzzy torque distribution controller for energy management (and emission control) of a parallel hybrid electric vehicle is proposed. The proposed controller is implemented in terms of a hierarchical architecture which incorporates the mode of operation of the vehicle as well as empirical knowledge of energy flow in each mode. Moreover, the rule set for each mode of operation of the vehicle is designed in view of an overall energy management strategy that ranges from maximal emphasis on battery charge sustenance to complete reliance on the electrical power source. The proposed control system is evaluated via computational simulations under the FTP75 urban drive cycle. Simulation results reveal that the proposed fuzzy torque distribution strategy is effective over the entire operating range of the vehicle in terms of performance, fuel economy and emissions. [source]

Fuzzy decision support for the control of detergent production

INTERNATIONAL JOURNAL OF ADAPTIVE CONTROL AND SIGNAL PROCESSING, Issue 8 2001
Magne Setnes
This paper describes a fuzzy decision support system (DSS) for the control of a detergent production process. The application has been carried out at a real-world, large-scale industrial production plant in the Netherlands, where a large variety of powder-based detergents for industrial users are produced in a spray drying process. The system consists of several fuzzy rule bases that model the control actions of experienced process operators in response to different quality deviations of the product. A hierarchical architecture of the fuzzy system is introduced to cope with the complexity. A fuzzy supervisor is used to deal with process constraints and to activate the applicable rule bases when control actions are needed. In this way, a system is obtained that enables the control of the process within stricter quality bounds than those applied by human operators alone. During in-production evaluation, the average improvement in the quality parameters for all product classes was above 30 percent. Copyright © 2001 John Wiley & Sons, Ltd. [source]

Fault-tolerant control of process systems using communication networks

AICHE JOURNAL, Issue 6 2005
Nael H. El-Farra
Abstract A methodology for the design of fault-tolerant control systems for chemical plants with distributed interconnected processing units is presented. Bringing together tools from Lyapunov-based nonlinear control and hybrid systems theory, the approach is based on a hierarchical architecture that integrates lower-level feedback control of the individual units with upper-level logic-based supervisory control over communication networks. The local control system for each unit consists of a family of control configurations for each of which a stabilizing feedback controller is designed and the stability region is explicitly characterized. The actuators and sensors of each configuration are connected, via a local communication network, to a local supervisor that orchestrates switching between the constituent configurations, on the basis of the stability regions, in the event of failures. The local supervisors communicate, through a plant-wide communication network, with a plant supervisor responsible for monitoring the different units and coordinating their responses in a way that minimizes the propagation of failure effects. The communication logic is designed to ensure efficient transmission of information between units, while also respecting the inherent limitations in network resources by minimizing unnecessary network usage and accounting explicitly for the effects of possible delays due to fault-detection, control computations, network communication and actuator activation. The proposed approach provides explicit guidelines for managing the various interplays between the coupled tasks of feedback control, fault-tolerance and communication. The efficacy of the proposed approach is demonstrated through chemical process examples. © 2005 American Institute of Chemical Engineers AIChE J, 2005 [source]

Chromatin dynamics of unfolding and refolding controlled by the nucleosome repeat length and the linker and core histones

BIOPOLYMERS, Issue 4 2007
Toshiro Kobori
Abstract Chromatin is composed of genomic DNA and histones, forming a hierarchical architecture in the nucleus. The chromatin hierarchy is common among eukaryotes despite different intrinsic properties of the genome. To investigate an effect of the differences in genome organization, chromatin unfolding processes were comparatively analyzed using Schizosaccaromyces pombe, Saccharomyces cerevisiae, and chicken erythrocyte. NaCl titration showed dynamic changes of the chromatin. 400,1000 mM NaCl facilitated beads with ,115 nm in diameter in S. pombe chromatin. A similar transition was also observed in S. cerevisiae chromatin. This process did not involve core histone dissociation from the chromatin, and the persistence length after the transition was ,26 nm for S. pombe and ,28 nm for S. cerevisiae, indicating a salt-induced unfolding to "beads-on-a-string" fibers. Reduced salt concentration recovered the original structure, suggesting that electrostatic interaction would regulate this discrete folding-unfolding process. On the other hand, the linker histone was extracted from chicken chromatin at 400 mM NaCl, and AFM observed the "beads-on-a-string" fibers around a nucleus. Unlike yeast chromatin, therefore, this unfolding was irreversible because of linker histone dissociation. These results indicate that the chromatin unfolding and refolding depend on the presence and absence of the linker histone, and the length of the linker DNA. © 2007 Wiley Periodicals, Inc. Biopolymers 85:295,307, 2007. This article was originally published online as an accepted preprint. The "Published Online" date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com [source]

Nanoscopic Morphologies in Block Copolymer Nanorods as Templates for Atomic-Layer Deposition of Semiconductors

ADVANCED MATERIALS, Issue 27 2009
Yong Wang
Block-copolymer nanorods containing mesopore structures derived from confinement-induced nanoscopic morphologies were used as templates for atomic-layer deposition. Diffusion of the ALD precursors through the polymeric scaffold and deposition of ZnO on the walls of the internal mesopores yielded 1D ZnO nanostructures with hierarchical architectures containing helices and stacked doughnuts as structure motifs. [source]

Combinatorial Hierarchically Ordered 2D Architectures Self-assembled from Nanocrystal Building Blocks,

ADVANCED MATERIALS, Issue 19 2008
Xiangxing Xu
A one-step, low-cost, and general nanocrystal self-assembly method that covers both the nanometer-scale superlattice and macroscale ordered patterns,that is, hierarchical architectures,is developed. This approach can generate various functional, compositional, and dimensional combinatorial architectures. It may give new opportunities in applications of catalysis, electronics, energy, magnetic devices, and bio-techniques. [source]