18,924 research outputs found
Variants of Plane Diameter Completion
The {\sc Plane Diameter Completion} problem asks, given a plane graph and
a positive integer , if it is a spanning subgraph of a plane graph that
has diameter at most . We examine two variants of this problem where the
input comes with another parameter . In the first variant, called BPDC,
upper bounds the total number of edges to be added and in the second, called
BFPDC, upper bounds the number of additional edges per face. We prove that
both problems are {\sf NP}-complete, the first even for 3-connected graphs of
face-degree at most 4 and the second even when on 3-connected graphs of
face-degree at most 5. In this paper we give parameterized algorithms for both
problems that run in steps.Comment: Accepted in IPEC 201
Genetic code on the dyadic plane
We introduce the simple parametrization for the space of codons (triples of
nucleotides) by 8\times 8 table. This table (which we call the dyadic plane)
possesses the natural 2-adic ultrametric. We show that after this
parametrization the genetic code will be a locally constant map of the simple
form. The local constancy of this map will describe degeneracy of the genetic
code.
The map of the genetic code defines 2-adic ultrametric on the space of amino
acids. We show that hydrophobic amino acids will be clustered in two balls with
respect to this ultrametric. Therefore the introduced parametrization of space
of codons exhibits the hidden regularity of the genetic code.Comment: Some gap in the construction was fixe
Evaluation of many load tests of passive rock bolts in the Czech Republic
Within the research project "FR-TI4/329 Research and development - creating an application system for the design and analysis of soil and rock anchors including the development of monitoring elements", an extensive stage of field load tests of rock bolts was carried out. The tests were conducted at 14 locations with varied rock composition. Before the initial tests, a loading stand was designed and constructed. A total of 201 pieces of tensile tests of bolts having lengths from 0.5 up to 2.5 m, a diameter of 22-32 mm, were performed. These were fully threaded rods, self-drilling rods, and fiberglass rods. The bolts were clamped into the cement and resin. The loading tests were always performed until material failure of bolts or shear stress failure at the interface cement-rock. At each location, basic geotechnical survey was carried out in the form of core drilling in a length of 3.0 metres with the assessment of the rock mass in situ, and laboratory testing of rock mechanics. Upon the completion of testing protocols, rock mass properties analysis was performed focusing on the evaluation of shear friction at the grouting-rock interface
Design study of Self-Alining Bearingless Planetary (SABP) gear
The feasibility of using the self alining, bearingless planetary (SABP) transmission in an uprated version of the OH-58 helicopter was evaluated, specific performance comparisons of this new transmission with contemporary helicopter transmission systems and with the uprated version of the OH-58 power transmission were made
Nanoscale switching characteristics of nearly tetragonal BiFeO3 thin films
We have investigated the nanoscale switching properties of strain-engineered
BiFeO3 thin films deposited on LaAlO3 substrates using a combination of
scanning probe techniques. Polarized Raman spectral analysis indicate that the
nearly-tetragonal films have monoclinic (Cc) rather than P4mm tetragonal
symmetry. Through local switching-spectroscopy measurements and piezoresponse
force microscopy we provide clear evidence of ferroelectric switching of the
tetragonal phase but the polarization direction, and therefore its switching,
deviates strongly from the expected (001) tetragonal axis. We also demonstrate
a large and reversible, electrically-driven structural phase transition from
the tetragonal to the rhombohedral polymorph in this material which is
promising for a plethora of applications.Comment: 10 pages, 6 figure
The Minimum Backlog Problem
We study the minimum backlog problem (MBP). This online problem arises, e.g.,
in the context of sensor networks. We focus on two main variants of MBP.
The discrete MBP is a 2-person game played on a graph . The player
is initially located at a vertex of the graph. In each time step, the adversary
pours a total of one unit of water into cups that are located on the vertices
of the graph, arbitrarily distributing the water among the cups. The player
then moves from her current vertex to an adjacent vertex and empties the cup at
that vertex. The player's objective is to minimize the backlog, i.e., the
maximum amount of water in any cup at any time.
The geometric MBP is a continuous-time version of the MBP: the cups are
points in the two-dimensional plane, the adversary pours water continuously at
a constant rate, and the player moves in the plane with unit speed. Again, the
player's objective is to minimize the backlog.
We show that the competitive ratio of any algorithm for the MBP has a lower
bound of , where is the diameter of the graph (for the discrete
MBP) or the diameter of the point set (for the geometric MBP). Therefore we
focus on determining a strategy for the player that guarantees a uniform upper
bound on the absolute value of the backlog.
For the absolute value of the backlog there is a trivial lower bound of
, and the deamortization analysis of Dietz and Sleator gives an
upper bound of for cups. Our main result is a tight upper
bound for the geometric MBP: we show that there is a strategy for the player
that guarantees a backlog of , independently of the number of cups.Comment: 1+16 pages, 3 figure
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