279 research outputs found
Tightly Coupled Array Antennas for Ultra-Wideband Wireless Systems
Tightly coupled array (TCA) antenna has become a hot topic of research recently, due to its
potential of enabling one single antenna array to operate over an extremely wide frequency range. Such an
array antenna is promising for applications in numerous wideband/multi-band and multi-function wireless
systems such as wideband high-resolution radars, 5G mobile communications, satellite communications,
global navigation satellite systems, sensors, wireless power transmission, internet of things and so on. Many
papers on this topic have been published by researchers internationally. This paper provides a detailed
review of the recent development on TCA that utilizes the capacitive coupling. The basic principles and the
historical evolution of the TCAs are introduced firstly. Then, recent development in the analysis and design
of TCAs, such as equivalent circuit analysis, bandwidth limitation analysis, array elements, feed structures,
substrates/superstrates loading, etc., are explained and discussed. The performances of the state-of-the-art
TCAs are presented and a comparison amongst some TCAs reported recently is summarized and discussed.
To illustrate the practical designs of TCA, one case study is provided, and the detailed design procedures of
the TCA are explained so as to demonstrate the TCA design methodology. Simulated results including the
VSWR at different angles of scanning, patterns and antenna gain are shown and discussed. A conclusion
and future work are given in the end
Incremental proximal methods for large scale convex optimization
Laboratory for Information and Decision Systems Report LIDS-P-2847We consider the minimization of a sum∑m [over]i=1 fi (x) consisting of a large
number of convex component functions fi . For this problem, incremental methods
consisting of gradient or subgradient iterations applied to single components have
proved very effective. We propose new incremental methods, consisting of proximal
iterations applied to single components, as well as combinations of gradient, subgradient,
and proximal iterations. We provide a convergence and rate of convergence
analysis of a variety of such methods, including some that involve randomization in
the selection of components.We also discuss applications in a few contexts, including
signal processing and inference/machine learning.United States. Air Force Office of Scientific Research (grant FA9550-10-1-0412
Study of J/psi decays to Lambda Lambdabar and Sigma0 Sigma0bar
The branching ratios and Angular distributions for J/psi decays to Lambda
Lambdabar and Sigma0 Sigma0bar are measured using BESII 58 million J/psi.Comment: 11 pages, 5 figure
Measurements of J/psi Decays into 2(pi+pi-)eta and 3(pi+pi-)eta
Based on a sample of 5.8X 10^7 J/psi events taken with the BESII detector,
the branching fractions of J/psi--> 2(pi+pi-)eta and J/psi-->3(pi+pi-)eta are
measured for the first time to be (2.26+-0.08+-0.27)X10^{-3} and
(7.24+-0.96+-1.11)X10^{-4}, respectively.Comment: 11 pages, 6 figure
Study of
New data are presented on from a sample of 58M
events in the upgraded BES II detector at the BEPC. There is a
conspicuous signal for and a peak at higher mass which
may be fitted with . From a combined analysis with
data, the branching ratio
is at the 95%
confidence level.Comment: 11 pages, 5 figures. Submitted to Phys. Lett.
BESII Detector Simulation
A Monte Carlo program based on Geant3 has been developed for BESII detector
simulation. The organization of the program is outlined, and the digitization
procedure for simulating the response of various sub-detectors is described.
Comparisons with data show that the performance of the program is generally
satisfactory.Comment: 17 pages, 14 figures, uses elsart.cls, to be submitted to NIM
Measurement of branching fractions for the inclusive Cabibbo-favored ~K*0(892) and Cabibbo-suppressed K*0(892) decays of neutral and charged D mesons
The branching fractions for the inclusive Cabibbo-favored ~K*0 and
Cabibbo-suppressed K*0 decays of D mesons are measured based on a data sample
of 33 pb-1 collected at and around the center-of-mass energy of 3.773 GeV with
the BES-II detector at the BEPC collider. The branching fractions for the
decays D+(0) -> ~K*0(892)X and D0 -> K*0(892)X are determined to be BF(D0 ->
\~K*0X) = (8.7 +/- 4.0 +/- 1.2)%, BF(D+ -> ~K*0X) = (23.2 +/- 4.5 +/- 3.0)% and
BF(D0 -> K*0X) = (2.8 +/- 1.2 +/- 0.4)%. An upper limit on the branching
fraction at 90% C.L. for the decay D+ -> K*0(892)X is set to be BF(D+ -> K*0X)
< 6.6%
Measurements of Cabibbo Suppressed Hadronic Decay Fractions of Charmed D0 and D+ Mesons
Using data collected with the BESII detector at storage ring
Beijing Electron Positron Collider, the measurements of relative branching
fractions for seven Cabibbo suppressed hadronic weak decays ,
, and , , and are presented.Comment: 11 pages, 5 figure
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