Evacuating Two Robots from a Disk: A Second Cut

We present an improved algorithm for the problem of evacuating two robots from the unit disk via an unknown exit on the boundary. Robots start at the center of the disk, move at unit speed, and can only communicate locally. Our algorithm improves previous results by Brandt et al. [CIAC'17] by introducing a second detour through the interior of the disk. This allows for an improved evacuation time of $5.6234$. The best known lower bound of $5.255$ was shown by Czyzowicz et al. [CIAC'15].Comment: 19 pages, 5 figures. This is the full version of the paper with the same title accepted in the 26th International Colloquium on Structural Information and Communication Complexity (SIROCCO'19

Segregation of Admixing Elements in the Boundary Layer of the Main Inlet of a Ductile Iron Casting

The object of the present paper is to determine the distribution of admixing elements, such as magnesium, manganese, silicon and sulfur, in the boundary layer of the main inlet of a ductile iron casting. The authors also intend to demonstrate the influence of elements diffusing from the casting mold, such as oxygen and silica, on the chemical composition of the boundary layer of the casting

Maximal sets of Hamilton cycles in Kn,n

In this article, we prove that there exists a maximal set of m Hamilton cycles in K-n,K-n if and only if n/4 < m less than or equal to n/2. (C) 2000 John Wiley & Sons, Inc

Initial Assessment of Graphite Precipitates in Vermicular Cast Iron in the As-Cast State and after Thermal Treatments

The purpose of the work was to determine the morphology of graphite that occurs in vermicular cast iron, both in the as-cast state and after heat treatment including austenitization (held at a temperature of 890°C or 960°C for 90 or 150 min) and isothermal quenching (i.e. austempering, at a temperature of 290°C or 390°C for 90 or 150 min). In this case, the aim here was to investigate whether the heat treatment performed, in addition to the undisputed influence of the cast iron matrix on the formation of austenite and ferrite, also affects the morphology of the vermicular graphite precipitates and to what extent. The investigations were carried out for the specimens cut from test coupons cast in the shape of an inverted U letter (type IIb according to the applicable standard); they were taken from the 25mm thick walls of their test parts. The morphology of graphite precipitates in cast iron was investigated using a Metaplan 2 metallographic microscope and a Quantimet 570 Color image analyzer. The shape factor F was calculated as the quotient of the area of given graphite precipitation and the square of its perimeter. The degree of vermicularization of graphite was determined as the ratio of the sum of the graphite surface and precipitates with F <0.05 to the total area occupied by all the precipitations of the graphite surface. The examinations performed revealed that all the heat-treated samples made of vermicular graphite exhibited the lower degree of vermicularization of the graphite compared to the corresponding samples in the as-cast state (the structure contains a greater fraction of the nodular or nearly nodular precipitates). Heat treatment also caused a reduction in the average size of graphite precipitates, which was about 225μm2 for the as-cast state, and dropped to approximately 170-200 μm2 after the austenitization and austempering processes

Spectroscopy in carbon deposits characterization

Carbon deposits formed on the top of the catalysts is characterized by a different morphology. This depends, among the others, on the temperature of the catalytical reaction conducted. Application of FT-IR/PA (Fourier transform infrared photoacoustic) spectroscopy allows to distinguish the carbon deposit forms created during the reaction. Deposits formed at high temperature (steam reforming, hydrogenolysis) are graphite-like materials. In the contrary, at low temperature (hydrogenation of benzene) deposits formed exhibit functional groups on its surface. Moreover, deposit created at low temperature has two parts: soluble and insoluble

FT-IR/PAS characteristic of the Ni-NiO/Al2_{2}O3_{3} catalyst

Carbon deposits formed on the catalysts' surface is characterized by the different properties. This depends, among others, on the temperature of the catalytic reaction conducted. Application of FT-IR/PA (Fourier transform infrared photoacoustic) spectroscopy allows to examine the carbon deposit forms created during the reaction. Samples of the commercial KUB-3 catalyst (Ni-NiO/Al$_{2}$O$_{3}$) taken from the industrial bed after three-year continuous work (applied for the hydrogenation of benzene) were characterized by means of FT-IR/PAS

Characterization of activated carbons by FT-IR/PAS and TPD

Commercial carbon NORIT and carbon xerogel samples were modified in an oxidizing atmosphere (wet and dry oxidation) and than subjected to physico-chemical characteristic, including temperature-programmed desorption (TPD) of CO and CO$_2$, and spectroscopic analysis. Surface changes due to oxidation procedure were monitored by FT-IR/PAS