65,672 research outputs found
Distributed Private Heavy Hitters
In this paper, we give efficient algorithms and lower bounds for solving the
heavy hitters problem while preserving differential privacy in the fully
distributed local model. In this model, there are n parties, each of which
possesses a single element from a universe of size N. The heavy hitters problem
is to find the identity of the most common element shared amongst the n
parties. In the local model, there is no trusted database administrator, and so
the algorithm must interact with each of the parties separately, using a
differentially private protocol. We give tight information-theoretic upper and
lower bounds on the accuracy to which this problem can be solved in the local
model (giving a separation between the local model and the more common
centralized model of privacy), as well as computationally efficient algorithms
even in the case where the data universe N may be exponentially large
Fe and N self-diffusion in non-magnetic Fe:N
Fe and N self-diffusion in non-magnetic FeN has been studied using neutron
reflectivity. The isotope labelled multilayers, FeN/57Fe:N and Fe:N/Fe:15N were
prepared using magnetron sputtering. It was remarkable to observe that N
diffusion was slower compared to Fe while the atomic size of Fe is larger
compared to N. An attempt has been made to understand the diffusion of Fe and N
in non-magnetic Fe:N
Electricity from photovoltaic solar cells: Flat-Plate Solar Array Project final report. Volume VII: Module encapsulation
The Flat-Plate Solar Array (FSA) Project, funded by the U.S. Government and managed by the Jet Propulsion Laboratory, was formed in 1975 to develop the module/array technology needed to attain widespread terrestrial use of photovoltaics by 1985. To accomplish this, the FSA Project established and managed an Industry, University, and Federal Government Team to perform the needed research and development.
The objective of the Encapsulation Task was to develop, demonstrate, and qualify photovoltaic (PV) module encapsulation systems that would provide 20-year (later increased to 30-year) life expectancies in terrestrial environments, and which would be compatible with the cost and performance goals of the FSA Project. The scope of the Encapsulation Task included the identification, development, and evaluation of material systems and configurations required to support and protect the optically and electrically active solar cell circuit components in the PV module operating environment. Encapsulation material technologies summarized in this report include the development of low-cost ultraviolet protection techniques, stable low-cost pottants, soiling resistant coatings, electrical isolation criteria, processes for optimum interface bonding, and analytical and experimental tools for evaluating the long-term durability and structural adequacy of encapsulated modules. Field testing, accelerated stress testing, and design studies have demonstrated that encapsulation materials, processes, and configurations are available that will meet the FSA cost and performance goals. Thirty-year module life expectancies are anticipated based on accelerated stress testing results and on extrapolation of real-time field exposures in excess of 9 years
Full QCD with the L\"uscher local bosonic action
We investigate L\"uscher's method of including dynamical Wilson fermions in a
lattice simulation of QCD with two quark flavours. We measure the accuracy of
the approximation by comparing it with Hybrid Monte Carlo results for gauge
plaquette and Wilson loops. We also introduce an additional global Metropolis
step in the update. We show that the complexity of L\"uscher's algorithm
compares favourably with that of the Hybrid Monte Carlo.Comment: 21 pages Late
Aharonov-Bohm effect in the presence of evanescent modes
It is known that differential magnetoconductance of a normal metal loop
connected to reservoirs by ideal wires is always negative when an electron
travels as an evanescent modes in the loop. This is in contrast to the fact
that the magnetoconductance for propagating modes is very sensitive to small
changes in geometric details and the Fermi energy and moreover it can be
positive as well as negative. Here we explore the role of impurities in the
leads in determining the magnetoconductance of the loop. We find that the
change in magnetoconductance is negative and can be made large provided the
impurities do not create resonant states in the systems. This theoretical
finding may play an useful role in quantum switch operations.Comment: 9 figures available on reques
Specific heat at constant volume in the thermodynamic model
A thermodynamic model for multifragmentation which is frequently used appears
to give very different values for specific heat at constant volume depending
upon whether canonical or grand canonical ensemble is used. The cause for this
discrepancy is analysed.Comment: Revtex, 7 pages including 4 figure
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