Structural and resistance switching properties of ZnO₃/ SrTiO/GaAs heterostructure grown by laser molecular beam epitaxy

Author name used in this publication: J. Y. Dai2010-2011 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishe

Vertex operator algebras and operads

Vertex operator algebras are mathematically rigorous objects corresponding to chiral algebras in conformal field theory. Operads are mathematical devices to describe operations, that is, $n$-ary operations for all $n$ greater than or equal to $0$, not just binary products. In this paper, a reformulation of the notion of vertex operator algebra in terms of operads is presented. This reformulation shows that the rich geometric structure revealed in the study of conformal field theory and the rich algebraic structure of the theory of vertex operator algebras share a precise common foundation in basic operations associated with a certain kind of (two-dimensional) ``complex'' geometric object, in the sense in which classical algebraic structures (groups, algebras, Lie algebras and the like) are always implicitly based on (one-dimensional) ``real'' geometric objects. In effect, the standard analogy between point-particle theory and string theory is being shown to manifest itself at a more fundamental mathematical level.Comment: 16 pages. Only the definitions of "partial operad" and of "rescaling group" have been improve

Chaoization of switched reluctance motor drives

This paper presents a new technique for the chaoiztion of switched reluctance motor (SRM) drivers. Based on the chaotic modeling of SRM drives, effects of feedback controller gains on the stability of the rotor speed are investigated. In accordance, a control strategy combining piecewise proportional feedback and time-delayed feedback is proposed to produce bound-controllable oscillation around any specific rotor speed. To estimate the continuous influence of a certain control parameter, a Poincaré map sampling at every extreme points is constructed, then the bifurcation diagrams are drawn. Theoretical analysis and numerical simulation for a practical 12/8 motor driver are also given.published_or_final_versio

Optimal manufacturing/remanufacturing policies with fixed investment for the underdeveloped remanufacturing system

© 2017, Strojarski Facultet. All rights reserved. In an underdeveloped remanufacturing system, poor infrastructure and low technical level impede further development of remanufacturing. To overcome this obstacle, a huge amount of fixed investment is required to improve the remanufacturing system. However, this investment inevitably influences the manufacturer’s manufacturing/remanufacturing decision-making economically. The relationship between fixed investment and recycling ratio was investigated, and the two- and multi-period manufacturing/remanufacturing mixed optimization models were developed. Based on the Karush-Kuhn-Tucker (KKT) conditions, the optimal manufacturing/remanufacturing and fixed investment policies were obtained in closed-form expressions. Moreover, the influences of the fixed investment were analysed. Results show that the optimal policies are significantly influenced by the degree of underdevelopment of the remanufacturing system. When the remanufacturing system is underdeveloped, the manufacturer shows a lack of enthusiasm in remanufacturing, thereby resulting in the decrease of the investment and the recycling ratio. The manufacturer raises the sale price to alleviate the loss caused by fixed investment, but the total manufacturing quantity and profit decrease. In the multi-period case, the manufacturer gradually increases the investment for continuously improving the remanufacturing system to increase the recycling ratio and obtain additional profits from remanufacturing. The proposed models can effectively provide the reference for determining the reasonable manufacturing/remanufacturing and fixed investment policies in the underdeveloped remanufacturing system

Structural and dielectric properties of epitaxial SrTiO₃films grown directly on GaAs substrates by laser molecular beam epitaxy

Author name used in this publication: Z. P. WuAuthor name used in this publication: K. H. Wong2008-2009 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishe

Static Trace-Based Deadlock Analysis for Synchronous Mini-Go

We consider the problem of static deadlock detection for programs in the Go programming language which make use of synchronous channel communications. In our analysis, regular expressions extended with a fork operator capture the communication behavior of a program. Starting from a simple criterion that characterizes traces of deadlock-free programs, we develop automata-based methods to check for deadlock-freedom. The approach is implemented and evaluated with a series of examples

Wavelength-multiplexed duplex transceiver based on III-V/Si hybrid integration for off-chip and on-chip optical interconnects

A six-channel wavelength-division-multiplexed optical transceiver with a compact footprint of 1.5 x 0.65 mm(2) for off-chip and on-chip interconnects is demonstrated on a single silicon-on-insulator chip. An arrayed waveguide grating is used as the (de)multiplexer, and III-V electroabsorption sections fabricated by hybrid integration technology are used as both modulators and detectors, which also enable duplex links. The 30-Gb/s capacity for each of the six wavelength channels for the off-chip transceiver is demonstrated. For the on-chip interconnect, an electrical-to-electrical 3-dB bandwidth of 13 GHz and a data rate of 30 Gb/s per wavelength are achieved

Residue codes of extremal Type II Z_4-codes and the moonshine vertex operator algebra

In this paper, we study the residue codes of extremal Type II Z_4-codes of length 24 and their relations to the famous moonshine vertex operator algebra. The main result is a complete classification of all residue codes of extremal Type II Z_4-codes of length 24. Some corresponding results associated to the moonshine vertex operator algebra are also discussed.Comment: 21 pages, shortened from v