12,814 research outputs found

### Effects of depolarizing quantum channels on BB84 and SARG04 quantum cryptography protocols

We report experimental studies on the effect of the depolarizing quantum
channel on weak-pulse BB84 and SARG04 quantum cryptography. The experimental
results show that, in real world conditions in which channel depolarization
cannot be ignored, BB84 should perform better than SARG04.Comment: 4 pages, 4 figure

### Impact of Direct Income Payments on Productive Efficiency of Korean Rice Farms

This paper examines the impact of direct income payments on productive efficiency of Korean rice farms, using farm-level cross sectional data in 2006. For representation of efficiency and its determinants, this paper uses a model that estimates the deviations of farms from a translog distance function and the determinants of these deviations. This paper especially estimates a stochastic frontier production function to explain deviations from best-practice productivity with a two-part error term including statistical noise from measurement error and technical inefficiency arising from farms not reaching the production frontier boundary. The empirical evidence finds that farms that get a higher share of direct payments in farm revenue are less efficient than others. This inefficiency is reduced by increases in farm size. Another result indicates that farms received greater direct payments on aggregate are more efficient than other farms since fixed payment, one part of rice direct payment, is tied to the amount of a farm's cropland that has been enrolled in programs, as well as yield histories.direct income payments, productive efficiency, stochastic frontier production function, Korea, Agribusiness, Agricultural and Food Policy, Crop Production/Industries,

### The structure of gauge-invariant ideals of labelled graph $C^*$-algebras

In this paper, we consider the gauge-invariant ideal structure of a
$C^*$-algebra $C^*(E,\mathcal{L},\mathcal{B})$ associated to a set-finite,
receiver set-finite and weakly left-resolving labelled space
$(E,\mathcal{L},\mathcal{B})$, where $\mathcal{L}$ is a labelling map assigning
an alphabet to each edge of the directed graph $E$ with no sinks. Under the
assumption that an accommodating set $\mathcal{B}$ is closed under taking
relative complement, it is obtained that there is a one to one correspondence
between the set of all hereditary saturated subsets of $\mathcal{B}$ and the
gauge-invariant ideals of $C^*(E,\mathcal{L},\mathcal{B})$. For this, we
introduce a quotient labelled space $(E,\mathcal{L},[\mathcal{B}]_R)$ arising
from an equivalence relation $\sim_R$ on $\mathcal{B}$ and show the existence
of the $C^*$-algebra $C^*(E,\mathcal{L},[\mathcal{B}]_R)$ generated by a
universal representation of $(E,\mathcal{L},[\mathcal{B}]_R)$. Also the
gauge-invariant uniqueness theorem for $C^*(E,\mathcal{L},[\mathcal{B}]_R)$ is
obtained.
For simple labelled graph $C^*$-algebras
$C^*(E,\mathcal{L},\bar{\mathcal{E}})$, where $\bar{\mathcal{E}}$ is the
smallest accommodating set containing all the generalized vertices, it is
observed that if for each vertex $v$ of $E$, a generalized vertex $[v]_l$ is
finite for some $l$, then $C^*(E,\mathcal{L},\bar{\mathcal{E}})$ is simple if
and only if $(E,\mathcal{L},\bar{\mathcal{E}})$ is strongly cofinal and
disagreeable. This is done by examining the merged labelled graph
$(F,\mathcal{L}_F)$ of $(E,\mathcal{L})$ and the common properties that
$C^*(E,\mathcal{L},\bar{\mathcal{E}})$ and
$C^*(F,\mathcal{L},\bar{\mathcal{F}})$ share

### Performance of SSE and AVX Instruction Sets

SSE (streaming SIMD extensions) and AVX (advanced vector extensions) are SIMD
(single instruction multiple data streams) instruction sets supported by recent
CPUs manufactured in Intel and AMD. This SIMD programming allows parallel
processing by multiple cores in a single CPU. Basic arithmetic and data
transfer operations such as sum, multiplication and square root can be
processed simultaneously. Although popular compilers such as GNU compilers and
Intel compilers provide automatic SIMD optimization options, one can obtain
better performance by a manual SIMD programming with proper optimization: data
packing, data reuse and asynchronous data transfer. In particular, linear
algebraic operations of vectors and matrices can be easily optimized by the
SIMD programming. Typical calculations in lattice gauge theory are composed of
linear algebraic operations of gauge link matrices and fermion vectors, and so
can adopt the manual SIMD programming to improve the performance.Comment: 7 pages, 5 figures, 4 tables, Contribution to proceedings of the 30th
International Symposium on Lattice Field Theory (Lattice 2012), June 24-29,
201

### Thermomechanics of Solid Oxide Fuel Cell Electrode Microstructures Using Finite Element Methods: Progressive Interface Degradation under Thermal Cycling

The electrochemical performance of solid oxide fuel cell (SOFC) is significantly influenced by three-phase boundary (TPB) zones in the microstructure. TPB zones are locations where all three phases comprising the microstructure such as the two solid phases and the pore phase are present. Electrochemical reactions such as oxygen reduction occur near TPBs, and TPB density is believed to affect the polarization resistance of the cathode. In this regard, the effect of interface degradation under repeated thermal loading on the mechanical integrity and electrochemical performance of solid oxide fuel cell (SOFC) electrodes is studied through finite element simulations. Image-based 3-D models are used in this study, with additional interface zones at the boundaries between dissimilar solid phases. These interface zones are composed of 3-D cohesive elements of small thickness. The effect of interface degradation on mechanical integrity is studied by subjecting 50:50 LSM:YSZ wt.% cathode models to increasing levels of thermal load from room temperature (20°C) up to operating temperature (820°C). Energy quantities (e.g., strain energy and damage dissipation) for cathode models with and without cohesive interface zones are obtained through finite element analysis (FEA). These quantities are compared using energy balance concepts from fracture mechanics to gain insight into the effects of interface degradation on mechanical integrity

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