10,686 research outputs found
The national security argument for protection of domestic industries
Tracing the origin of the national security argument for protection of domestic industries to Adam Smith, Alexander Hamilton, and Friedrich List, we study its post-GATT applications with reference to Article XXI of the WTO. We compare the use of tariff, production/input subsidy, and government procurement as alternative instruments of protection from the perspective of economic efficiency and study the disapproval of inward FDI to gain insights into the underlying national security concerns. The case studies of a) the US tariffs on aluminum and steel, b) German disapproval of the acquisition of a technology firm Leifeld Metal Spinning by a Chinese firm, and c) US’ all out global effort to cripple China’s telecom equipment giant Huawei are presented for illustration
Homotopy Method for the Large, Sparse, Real Nonsymmetric Eigenvalue Problem
A homotopy method to compute the eigenpairs, i.e., the eigenvectors and eigenvalues, of a given real matrix A1 is presented. From the eigenpairs of some real matrix A0, the eigenpairs of
A(t) ≡ (1 − t)A0 + tA1
are followed at successive "times" from t = 0 to t = 1 using continuation. At t = 1, the eigenpairs of the desired matrix A1 are found. The following phenomena are present when following the eigenpairs of a general nonsymmetric matrix:
• bifurcation,
• ill conditioning due to nonorthogonal eigenvectors,
• jumping of eigenpaths.
These can present considerable computational difficulties. Since each eigenpair can be followed independently, this algorithm is ideal for concurrent computers. The homotopy method has the potential to compete with other algorithms for computing a few eigenvalues of large, sparse matrices. It may be a useful tool for determining the stability of a solution of a PDE. Some numerical results will be presented
FeAs-based superconductivity: a case study of the effects of transition metal doping on BaFe2As2
The recently discovered FeAs-based superconductors are a new, promising set
of materials for both technological as well as basic research. They offer
transition temperatures as high as 55 K as well as essentially isotropic and
extremely large upper, superconducting critical fields in excess of 40 T at 20
K. In addition they may well provide insight into exotic superconductivity that
extends beyond just FeAs-based superconductivity, perhaps even shedding light
on the still perplexing CuO-based high-Tc materials. Whereas superconductivity
can be induced in the RFeAsO (R = rare earth) and AEFe2As2 (AE = Ba, Sr, Ca))
families by a number of means, transition metal doping of BaFe2As2, e.g.
Ba(Fe1-xTMx)2As2, offers the easiest experimental access to a wide set of
materials. In this review we present an overview and summary of the effect of
TM doping (TM = Co, Ni, Cu, Pd, and Rh) on BaFe2As2. The resulting phase
diagrams reveal the nature of the interaction between the structural, magnetic
and superconducting phase transitions in these compounds and delineate a region
of phase space that allows for the stabilization of superconductivity.Comment: edited and shortened version is accepted to AR:Condensed Matter
Physic
Smart Dispatch and Demand Forecasting for Large Grid Operations with Integrated Renewable Resources
Nonlinear Preconditioning: How to use a Nonlinear Schwarz Method to Precondition Newton's Method
For linear problems, domain decomposition methods can be used directly as
iterative solvers, but also as preconditioners for Krylov methods. In practice,
Krylov acceleration is almost always used, since the Krylov method finds a much
better residual polynomial than the stationary iteration, and thus converges
much faster. We show in this paper that also for non-linear problems, domain
decomposition methods can either be used directly as iterative solvers, or one
can use them as preconditioners for Newton's method. For the concrete case of
the parallel Schwarz method, we show that we obtain a preconditioner we call
RASPEN (Restricted Additive Schwarz Preconditioned Exact Newton) which is
similar to ASPIN (Additive Schwarz Preconditioned Inexact Newton), but with all
components directly defined by the iterative method. This has the advantage
that RASPEN already converges when used as an iterative solver, in contrast to
ASPIN, and we thus get a substantially better preconditioner for Newton's
method. The iterative construction also allows us to naturally define a coarse
correction using the multigrid full approximation scheme, which leads to a
convergent two level non-linear iterative domain decomposition method and a two
level RASPEN non-linear preconditioner. We illustrate our findings with
numerical results on the Forchheimer equation and a non-linear diffusion
problem
Structure formation in electromagnetically driven granular media
We report structure formation in submonolayers of magnetic microparticles
subjected to periodic electrostatic and magnetic excitations. Depending on the
excitation parameters, we observe the formation of a rich variety of
structures: clusters, rings, chains, and networks. The growth dynamics and
shapes of the structures are strongly dependent on the amplitude and frequency
of the external magnetic field. We find that for pure ac magnetic driving at
low densities of particles, the low-frequency magnetic excitation favors
clusters while high frequency excitation favors chains and net-like structures.
An abrupt phase transition from chains to a network phase was observed for a
high density of particles.Comment: 4 pages, 5 figure
Abrupt Transition from a Free, Repulsive to a Condensed, Attractive DNA Phase, Induced by Multivalent Polyamine Cations
We have investigated the energetics of DNA condensation by multivalent polyamine cations. Solution small angle x-ray scattering was used to monitor interactions between short 25 base pair dsDNA strands in the free supernatant DNA phase that coexists with the condensed DNA phase. Interestingly, when tetravalent spermine is used, significant inter-DNA repulsion is observed in the free phase, in contrast with the presumed inter-DNA attraction in the coexisting condensed phase. DNA condensation thus appears to be a discrete, first-order-like, transition from a repulsive gaseous to an attractive condensed solid phase, in accord with the reported all-or-none condensation of giant DNA. We further quantify the electrostatic repulsive potentials in the free DNA phase and estimate the number of additional spermine cations that bind to DNA upon condensation
Hearing Waves: A Philosophy of Sound and Auditory Perception
This dissertation aims to revive wave theory in the philosophy of sound. Wave theory identifies sounds with compression waves. Despite its wide acceptance in the scientific community as the default position, many philosophers have rejected wave theory and opted for different versions of distal theory instead. According to this current majority view, a sound has its stationary location at its source. I argue against this and other alternative philosophical theories of sound and develop wave theory into a more defensible form.
Philosophers of sound tend to emphasise how sounds are experienced to be in their arguments. Most often, it is assumed that that which appears to be a distally located bearer of auditory properties in an auditory experience is a sound. Chapter 1 argues that if this distal entity is the sound source instead, many of the existing theories of sound will be severely affected.
Chapter 2 discusses auditory perception and criticises the common assumption that we hear non-sound entities in virtue of hearing sounds. I show that this assumption begs the question against certain theories of sound and that the contrary view that sound sources can be directly heard is more plausible.
If sound sources can be directly heard, then features commonly attributed to sounds based on auditory experiences might rather be features of sound sources. I examine eight of such features in Chapter 3. Only four of them survive.
Chapters 4 and 5 review the existing theories of sound. After a taxonomy of existing theories of sound, each theory is criticised one-by-one. Some of them are problematic precisely because they rely on the implausible assumption that that which appears to be distally located in an auditory experience is a sound rather than a sound source.
Lastly, Chapter 6 focuses on wave theory. It begins with two positive arguments for wave theory in general, followed by my replies to two common objections in the literature. I then move on to develop my version of wave theory. There are two core aspects of my view. The first one is a metaphysics of compression waves; the second is an account of what it is to hear compression waves. After comparing my view with a similar theory, I demonstrate the explanatory power of my view in two steps. First, the eight commonly accepted features of sounds examined in Chapter 3 are revisited. It turns out that my view can accommodate all of them. Second, explanations for four special sound-related phenomena are offered at the end of the chapter.
I conclude in the last chapter with the suggestion that, as a philosopher, the best way to defend wave theory is to offer a better understanding of auditory perception which explains how compression waves are experienced
Physical properties of single crystalline BaSn5
We present a comprehensive study of the binary intermetallic superconductor,
BaSn5. High-quality single crystalline BaSn5 was grown out of Sn flux. Detailed
thermodynamic and transport measurements were performed to study BaSn5's normal
and superconducting state properties. This material appears to be a strongly
coupled, multiband superconductor. Hc2(T)is almost isotropic. De Haas-van
Alphen oscillations were observed and two effective masses were estimated from
the FFT spectra. Hydrostatic pressure causes a decrease in the superconducting
transition temperature at the rate of ~ -0.053 K/kbar.Comment: 8 pages and 9 figure
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