The lowest crossing in 2D critical percolation

We study the following problem for critical site percolation on the triangular lattice. Let A and B be sites on a horizontal line e separated by distance n. Consider, in the half-plane above e, the lowest occupied crossing R from the half-line left of A to the half-line right of B. We show that the probability that R has a site at distance smaller than m from AB is of order (log (n/m))^{-1}, uniformly in 1 <= m < n/2. Much of our analysis can be carried out for other two-dimensional lattices as well.Comment: 16 pages, Latex, 2 eps figures, special macros: percmac.tex. Submitted to Annals of Probabilit

Non-Perturbative U(1) Gauge Theory at Finite Temperature

For compact U(1) lattice gauge theory (LGT) we have performed a finite size scaling analysis on $N_{\tau} N_s^3$ lattices for $N_{\tau}$ fixed by extrapolating spatial volumes of size $N_s\le 18$ to $N_s\to\infty$. Within the numerical accuracy of the thus obtained fits we find for $N_{\tau}=4$, 5 and~6 second order critical exponents, which exhibit no obvious $N_{\tau}$ dependence. The exponents are consistent with 3d Gaussian values, but not with either first order transitions or the universality class of the 3d XY model. As the 3d Gaussian fixed point is known to be unstable, the scenario of a yet unidentified non-trivial fixed point close to the 3d Gaussian emerges as one of the possible explanations.Comment: Extended version after referee reports. 6 pages, 6 figure

Characterizing CDMA downlink feasibility via effective interference

This paper models and analyses downlink power assignment feasibility in Code Division Multiple Access (CDMA) mobile networks. By discretizing the area into small segments, the power requirements are characterized via a matrix representation that separates user and system characteristics. We obtain a closed-form analytical expression of the so-called Perron-Frobenius eigenvalue of that matrix, which provides a quick assessment of the feasibility of the power assignment for each distribution of calls over the segments. Although the obtained relation is non-linear, it basically provides an effective interference characterisation of downlink feasibility. Our results allow for a fast evaluation of outage and blocking probabilities, and enable a quick evaluation of feasibility that may be used for Call Acceptance Control. \u

A Pulsed Synchrotron for Muon Acceleration at a Neutrino Factory

A 4600 Hz pulsed synchrotron is considered as a means of accelerating cool muons with superconducting RF cavities from 4 to 20 GeV/c for a neutrino factory. Eddy current losses are held to less than a megawatt by the low machine duty cycle plus 100 micron thick grain oriented silicon steel laminations and 250 micron diameter copper wires. Combined function magnets with 20 T/m gradients alternating within single magnets form the lattice. Muon survival is 83%.Comment: 4 pages, 1 figures, LaTeX, 5th International Workshop on Neutrino Factories and Superbeams (NuFact 03), 5-11 Jun 2003, New Yor

µTransparent insulating channels as components for miniaturized chemical separation Devices

Currently, miniaturized devices that apply electro osmotic pumping or electrophoretic separations are mostly constructed by etching small insulating channels for supply and separation on glass substrates. In principle, silicon is a superior construction material in terms of inertness and design flexibility. However, because of its semiconducting properties, the use in high voltage applications like the ones mentioned above is quite limited. In this paper, the use of μTransparent Insulating Channel (μTIC) technology is demonstrated as a standard procedure to manufacture miniaturized analytical separation devices. This technique, μchannels having extremely thin, transparent and insulating walls can be fabricated. An overview of the impact of this technology is given, showing the advantages of a fabrication technology that is as flexible as silicon technology for the fabrication of μTAS or “lab on a chip” devices. The following basic technology and control parameters will be highlighted. 1. Up to 100 μm wide rectangular channels 2. Bosses and leak-free connections to external μ fluidics. 3. Web-like structures for inlets/outlets>100 μm. 4. Implementation of conductivity electrodes 5. Good thermal dissipation properties of the thin walls 6. Control of the electro osmotic flow by a radial voltage

A novel approach to low-power hot-surface devices with decoupled electrical and thermal resistances

This work employs the idea of maintaining a hot surface by means of dissipating power at a nano-scale conductive link. The link is created between two polysilicon electrodes separated by a dielectric (a capacitor-like structure). From modelling, a link of 10 nm in diameter should be possible to maintain the surface temperature ranging between 750 and 1150 K within the surface diameter of 2 μm by absorbing a 3.3 mW of electric power. The devices can also be designed in such a way that the hot surface area is reduced to a sub-μm-size hotspot. The main advantage of the proposed idea is decoupling the electrical resistance and thermal resistance of the device. In this paper, two device structures based on antifuse technology are described. Both the thermo-electrical properties and feasibility to perform as a Pellistor-type gas sensor are discussed

Deep drawing simulations of Tailored Blanks and experimental verification

Tailored Blanks are increasingly used in the automotive industry.\ud A combination of different materials, thickness, and coatings can be welded\ud together to form a blank for stamping car body panels. The main advantage\ud of using Tailored Blanks is to have specific characteristics at particular parts\ud of the blank in order to reduce the material weight and costs.\ud To investigate the behaviour of Tailored Blanks during deep drawing, the\ud finite element code DiekA is used. In this paper, simulations of the deep\ud drawing of two products using Tailored Blanks are discussed. For\ud verification, the two products are stamped to gain experimental information.\ud The correlation between the experimental results and the simulation results\ud appears to be satisfactory

Non-Extensive Bose-Einstein Condensation Model

The imperfect Boson gas supplemented with a gentle repulsive interaction is completely solved. In particular it is proved that it has non-extensive Bose-Einstein condensation, i.e., there is condensation without macroscopic occupation of the ground state (k=0) level