1,013 research outputs found
Solution of the Synthesis Problem of Boundary Optimal Control of a Rod Cooling Process with a Heat Conductive Viscosity
The problem of synthesis of the boundary optimal control of the cooling process of media with heat conductive viscosity is investigated. In addition to the distributed parameters, the concentrated parameters act on the system. This is due to the fact that the temperature of the external environment is unknown and varies according to a given law. As a result, the process is described by a system of partial differential equations and ordinary differential equations. In this case, heat transfer occurs at the right end of the rod. This complicates the obtaining of a solution of this boundary-value problem in an explicit form. But it is possible to establish the existence and uniqueness of the solution of the corresponding boundary-value problem for concrete admissible controls.The criterion of quality is a quadratic functional and it is required to build control in the form of feedback. First by the Fourier method, the problem under consideration is formulated in an infinite-dimensional phase space. As a result, the problem of synthesis of optimal control in a functional space is obtained. To solve this problem, the dynamic programming method is used. To do this, let's introduce the Bellman functional and obtain the Bellman equation, which this functional satisfies. The solution of this equation allows to find the control parameter in the form of a functional defined on the set of the state function. Further, by introducing the corresponding functions, feedback control is constructed for the original problem. Unlike program control, this allows to influence the behavior of the system at any time, that is, to ensure the self-regulation of the process. However, let's note that the difficulties in solving this problem are connected with the justification of the proposed method. This is established by the investigation of a closed system
Conductivity landscape of highly oriented pyrolytic graphite surface containing ribbons and edges
We present an extensive study on electrical spectroscopy of graphene ribbons
and edges of highly oriented pyrolytic graphite (HOPG) using atomic force
microscope (AFM). We have addressed in the present study two main issues, (1)
How does the electrical property of the graphite (graphene) sheet change when
the graphite layer is displaced by shear forces? and (2) How does the
electrical property of the graphite sheet change across a step edge? While
addressing these two issues we observed, (1) variation of conductance among the
graphite ribbons on the surface of HOPG. The top layer always exhibits more
conductance than the lower layers, (2) two different monolayer ribbons on the
same sheet of graphite shows different conductance, (3) certain ribbon/sheet
edges show sharp rise in current, (4) certain ribbons/sheets on the same edge
shows both presence and absense of the sharp rise in the current, (5) some
lower layers at the interface near a step edge shows a strange dip in the
current/conductance (depletion of charge). We discuss possible reasons for such
rich conducting landscape on the surface of graphite.Comment: 13 pages, 9 figures. For better quality figures please contact autho
The Application of Constraint Rules to Data-driven Parsing
In this paper, we show an approach to extracting different types of constraint rules from a dependency treebank. Also, we show an approach to integrating these constraint rules into a dependency data-driven parser, where these constraint rules inform parsing decisions in specific situations where a set of parsing rule (which is induced from a classifier) may recommend several recommendations to the parser. Our experiments have shown that parsing accuracy could be improved by using different sets of constraint rules in combination with a set of parsing rules. Our parser is based on the arc-standard algorithm of MaltParser but with a number of extensions, which we will discuss in some detail
A simple single-source precursor route to the nanostructures of AlN, GaN and InN
In an effort to find a simple and common single-source precursor route for the group 13 metal nitride semiconductor nanostructures, the complexes formed by the trichlorides of Al, Ga and In with urea have been investigated. The complexes, characterized by X-ray crystallography and other techniques, yield the nitrides on thermal decomposition. Single crystalline nanowires of AlN, GaN and InN have been deposited on Si substrates covered with Au islands by using the complexes as precursors. The urea complexes yield single crystalline nanocrystals under solvothermal conditions. The successful synthesis of the nanowires and nanocrystals of these three important nitrides by a simple single-precursor route is noteworthy and the method may indeed be useful in practice
Soft chemical routes to semiconductor nanostructures
Soft chemistry has emerged as an important means of generating nanocrystals, nanowires and other nanostructures of semiconducting materials. We describe the synthesis of CdS and other metal chalcogenide nanocrystals by a solvothermal route. We also describe the synthesis of nanocrystals of AlN, GaN and InN by the reaction of hexamethyldisilazane with the corresponding metal chloride or metal cupferronate under solvothermal conditions. Nanowires of Se and Te have been obtained by a self-seeding solution-based method. A single source precursor based on urea complexes of metal chlorides gives rise to metal nitride nanocrystals, nanowires and nanotubes. The liquidliquid interface provides an excellent medium for preparing single-crystalline films of metal chalcogenides
InN nanocrystals, nanowires, and nanotubes
Various chemical methods have been utilized to prepare InN nanocrystals, nanowires and nanotubes, which have been characterized by several techniques (see TEM images). The nanostructures exhibit an absorption band in the near-IR region at around 0.7 eV, which rather than being caused by defects, is shown to be an intrinsic and characteristic feature of InN
Stanley's conjecture for critical ideals
Let S=K[x_1,x_2,...,x_n] be a polynomial ring in n variables over a field K.
Stanley's conjecture holds for the modules I and S/I, when I is a critical
monomial ideal. We calculate the Stanley depth of S/I when I is a canonical
critical monomial ideal. For non critical monomial ideals we show the existence
of a Stanley ideal with the same depth and Hilbert function.Comment: 5 page
Suppression of optical damage at 532 nm in Holmium doped congruent lithium niobate
Optical damage experiments were carried out in a series of Holmium doped congruent lithium niobate (Ho:cLN) crystals as a function of dopant concentration and laser intensity. The light induced beam distortion was recorded with a camera and a detector under the pseudo-Zscan configuration. At 532 nm, strong suppression of the optical damage was observed for the 0.94 mol. % doped crystal. Increased resistance to optical damage was also observed at 488 nm. The suppression of the optical damage is predominantly attributed to the reduction of the Nb antisites due to the holmium doping
Workplace misconduct and the requirement of due inquiry: with reference to the practice in Malaysia
This paper discusses the concept of workplace misconduct and the requirement of a domestic or due inquiry to establish the alleged act and with reference to the practice in Malaysia. The issues considered herein are as follows: (a) whether the disciplinary or domestic inquiry is essential in an impending dismissal for alleged gross misconduct; and (b) whether the dismissal carried out without convening a disciplinary inquiry violates the principles of natural justice thereby rendering the dismissal unfair
Liquid racism and the Danish Prophet Muhammad cartoons
This is the author's accepted manuscript. The final published article is available from the link below. Copyright @ 2010 The Author.This article examines reactions to the October 2005 publication of the Prophet Muhammad cartoons in the Danish newspaper Jyllands-Posten. It does so by using the concept of âliquid racismâ. While the controversy arose because it is considered blasphemous by many Muslims to create images of the Prophet Muhammad, the article argues that the meaning of the cartoons is multidimensional, that their analysis is significantly more complex than most commentators acknowledge, and that this complexity can best be addressed via the concept of liquid racism. The article examines the liquidity of the cartoons in relation to four readings. These see the cartoons as: (1) a criticism of Islamic fundamentalism; (2) blasphemous images; (3) Islamophobic and racist; and (4) satire and a defence of freedom of speech. Finally, the relationship between postmodernity and the rise of fundamentalism is discussed because the cartoons, reactions to them, and Islamic fundamentalism, all contain an important postmodern dimension.ESR
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