83,858 research outputs found
Analysis of the Total Food Folate Intake Data from the National Health and Nutrition Exa-amination Survey (Nhanes) Using Generalized Linear Model
The National health and nutrition examination survey (NHANES) is a respected nation-wide program in charge of assessing the health and nutritional status of adults and children in United States. Recent cal research found that folic acid play an important role in preventing baby birth defects. In this paper, we use the generalized estimating equation (GEE) method to study the generalized linear model (GLM) with compound symmetric correlation matrix for the NHANES data and investigate significant factors to ence the intake of food folic acid
Semantically Secure Lattice Codes for Compound MIMO Channels
We consider compound multi-input multi-output (MIMO) wiretap channels where
minimal channel state information at the transmitter (CSIT) is assumed. Code
construction is given for the special case of isotropic mutual information,
which serves as a conservative strategy for general cases. Using the flatness
factor for MIMO channels, we propose lattice codes universally achieving the
secrecy capacity of compound MIMO wiretap channels up to a constant gap
(measured in nats) that is equal to the number of transmit antennas. The
proposed approach improves upon existing works on secrecy coding for MIMO
wiretap channels from an error probability perspective, and establishes
information theoretic security (in fact semantic security). We also give an
algebraic construction to reduce the code design complexity, as well as the
decoding complexity of the legitimate receiver. Thanks to the algebraic
structures of number fields and division algebras, our code construction for
compound MIMO wiretap channels can be reduced to that for Gaussian wiretap
channels, up to some additional gap to secrecy capacity.Comment: IEEE Trans. Information Theory, to appea
Bandwidth control of forbidden transmission gaps in compound structures with subwavelength slits
Phase resonances in transmission compound structures with subwavelength slits
produce sharp dips in the transmission response. For all equal slits, the
wavelengths of these sharp transmission minima can be varied by changing the
width or the length of all the slits. In this paper we show that the width of
the dip, i.e., the frequency range of minimum transmittance, can be controlled
by making at least one slit different from the rest within a compound unit
cell. In particular, we investigate the effect that a change in the dielectric
filling, or in the length of a single slit produces in the transmission
response. We also analyze the scan angle behavior of these structures by means
of band diagrams, and compare them with previous results for all-equal slit
structures.Comment: 16 pages, 5 figures, submitted to Phys. Rev.
A Generalized Index for Static Voltage Stability of Unbalanced Polyphase Power Systems including Th\'evenin Equivalents and Polynomial Models
This paper proposes a Voltage Stability Index (VSI) suitable for unbalanced
polyphase power systems. To this end, the grid is represented by a polyphase
multiport network model (i.e., compound hybrid parameters), and the aggregate
behavior of the devices in each node by Th\'evenin Equivalents (TEs) and
Polynomial Models (PMs), respectively. The proposed VSI is a generalization of
the known L-index, which is achieved through the use of compound electrical
parameters, and the incorporation of TEs and PMs into its formal definition.
Notably, the proposed VSI can handle unbalanced polyphase power systems,
explicitly accounts for voltage-dependent behavior (represented by PMs), and is
computationally inexpensive. These features are valuable for the operation of
both transmission and distribution systems. Specifically, the ability to handle
the unbalanced polyphase case is of particular value for distribution systems.
In this context, it is proven that the compound hybrid parameters required for
the calculation of the VSI do exist under practical conditions (i.e., for lossy
grids). The proposed VSI is validated against state-of-the-art methods for
voltage stability assessment using a benchmark system which is based on the
IEEE 34-node feeder
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