3,881 research outputs found
Properties of Generalized Forchheimer Flows in Porous Media
The nonlinear Forchheimer equations are used to describe the dynamics of
fluid flows in porous media when Darcy's law is not applicable. In this
article, we consider the generalized Forchheimer flows for slightly
compressible fluids and study the initial boundary value problem for the
resulting degenerate parabolic equation for pressure with the time-dependent
flux boundary condition. We estimate -norm for pressure and its time
derivative, as well as other Lebesgue norms for its gradient and second spatial
derivatives. The asymptotic estimates as time tends to infinity are emphasized.
We then show that the solution (in interior -norms) and its gradient
(in interior -norms) depend continuously on the initial and
boundary data, and coefficients of the Forchheimer polynomials. These are
proved for both finite time intervals and time infinity. The De Giorgi and
Ladyzhenskaya-Uraltseva iteration techniques are combined with uniform
Gronwall-type estimates, specific monotonicity properties, suitable parabolic
Sobolev embeddings and a new fast geometric convergence result.Comment: 63 page
Tournament-Based Incentives and Mergers and Acquisitions
This research examines the relation between tournament-based incentives, which are proxied by the difference between a firm’s CEO pay and the median pay of the senior managers, and mergers and acquisitions (M&As). We find that tournament-based incentives are positively related to firm acquisitiveness and acquiring firms’ stock and operating performance. Further analysis indicates that positive acquisition performance increases the likelihood of the CEO being promoted from inside the acquiring firm. Our evidence is consistent with the view that tournament-based incentives motivate acquiring firms’ managers to make greater efforts and take more risk that result in superior acquisition performance
Mechanical Attributes of Fractal Dragons
Fractals are ubiquitous natural emergences that have gained increased
attention in engineering applications, thanks to recent technological
advancements enabling the fabrication of structures spanning across many
spatial scales. We show how the geometries of fractals can be exploited to
determine their important mechanical properties, such as the first and second
moments, which physically correspond to the center of mass and the moment of
inertia, using a family of complex fractals known as the dragons
The software for oceanographic data management: VODC for PC 2.0
To manage and process a large amount of oceanographic data, users must have powerful tools that simplify these tasks. The VODC for PC is software designed to assist in managing oceanographic data. It based on 32 bits Windows operation system and used Microsoft Access database management system. With VODC for PC users can update data simply, convert to some international data formats, combine some VODC databases to one, calculate average, min, max fields for some types of data, check for valid data
Halliday\u27s Functional Grammar: Philosophical Foundation and Epistemology
It is difficult to track the philosophy foundation and epistemology of systemic functional grammar (SFG) formulated by Halliday in the 1980s as this kind of grammar views language as a systemic resource for meaning. Besides, it has had global impacts on linguistics and flourished in contemporary linguistic theory. Anyone who is familiar with Halliday\u27s work realizes that his SFG is an approach designed to analyze English texts. Halliday (1994: xv) explicitly states that “to construct a grammar for purposes of text analysis: one that would make it possible to say sensible and useful things about any text, spoken or written, in modern English.” The aim of this study is not about the applicability of SFG to text analysis as many researchers and scholars do. Our efforts are made to clarify the philosophical foundation of Halliday\u27s SFG. The paper presents on triangle: (i) language, mind and world; (ii) and empiricism in Halliday\u27s SFG
Optothermotronic effect as an ultrasensitive thermal sensing technology for solid-state electronics
The thermal excitation, regulation, and detection of charge carriers in solid-state electronics have attracted great attention toward high-performance sensing applications but still face major challenges. Manipulating thermal excitation and transport of charge carriers in nanoheterostructures, we report a giant temperature sensing effect in semiconductor nanofilms via optoelectronic coupling, termed optothermotronics. A gradient of charge carriers in the nanofilms under nonuniform light illumination is coupled with an electric tuning current to enhance the performance of the thermal sensing effect. As a proof of concept, we used silicon carbide (SiC) nanofilms that form nanoheterostructures on silicon (Si). The sensing performance based on the thermal excitation of charge carriers in SiC is enhanced by at least 100 times through photon excitation, with a giant temperature coefficient of resistance (TCR) of up to −50%/K. Our findings could be used to substantially enhance the thermal sensing performance of solid-state electronics beyond the present sensing technologies
The Vietnamese shrimp trade: livelihoods analysis of stakeholders and market chain analysis
Aquaculture and capture fisheries in Vietnam have been increasing fast in the last decade, especially aquaculture growth rate is 12% for the 1999 – 2003 period, contributing a significant part into the hunger eradication and poverty reduction1. Vietnam is to be ranked into one of the countries potential to produce the aquatic economic in the world, and the fact is that, after 40 years of establishing, the fisheries sector has made remarkable contributions to the country. By the list, at the moment the aquatic products make up about 4 - 5% of GDP and create job opportunities for over 3 three million
employees (VASEP, 2004), in which the largest contribution is from shrimp farming. [PDF contains 124 pages.
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