16,319 research outputs found
Cup-length estimates for leaf-wise intersections
We prove that on a restricted contact type hypersurface the number of
leaf-wise intersections is bounded from below by a certain cup-length.Comment: 13 pages, 4 figures; v2: minor modification
Within-burst synchrony changes for coupled elliptic bursters
We study the appearance of a novel phenomenon for linearly coupled identical
bursters: synchronized bursts where there are changes of spike synchrony within
each burst. The examples we study are for normal form elliptic bursters where
there is a periodic slow passage through a Bautin (codimension two degenerate
Andronov-Hopf) bifurcation. This burster has a subcritical Andronov-Hopf
bifurcation at the onset of repetitive spiking while end of burst occurs via a
fold limit cycle bifurcation. We study synchronization behavior of two and
three Bautin-type elliptic bursters for a linear direct coupling scheme. Burst
synchronization is known to be prevalent behavior among such coupled bursters,
while spike synchronization is more dependent on the details of the coupling.
We note that higher order terms in the normal form that do not affect the
behavior of a single burster can be responsible for changes in synchrony
pattern; more precisely, we find within-burst synchrony changes associated with
a turning point in the spiking frequency.Comment: 17 pages, 13 figures, 2 table
A Combined Organic Rankine Cycle-Heat Pump System for Domestic Hot Water Application
This paper investigates a novel system to improve the efficiency of using natural gas for domestic heating. The exhaust from a gas burner powers a small-scale Organic Rankine Cycle (ORC) system using hexane as the working fluid, which is used to directly drive the compressor of a heat pump, using R134a as the working fluid. Water is heated from ambient by passing it through three heat exchangers, the condenser of the Heat Pump, the condenser of the ORC, and the secondary heat exchanger that is heated by the hot flue gas from the burner after it transfers the heat to the evaporator of the ORC subsystem. By using the heat generated from the burning of gas in a burner in this way, a fuel-to-usable-heat efficiency of up to 160% is projected, outperforming the other technologies discussed, giving it the potential to significantly reduce energy demand and carbon emissions. This paper investigates the effect of varying ambient conditions upon the cycle, namely the temperature of ambient air, which has a strong effect on the performance of the heat pump
On-chip timing measurement architecture with femtosecond resolution
A new timing measurement architecture based on the time-to-digital conversion technique is presented. The architecture occupies a small silicon area (200x185µm) in a 0.12µm CMOS Process and can achieve tens of femtoseconds timing resolution, which is the highest reported to date
Advancement in Color Image Processing using Geometric Algebra
This paper describes an advancement in color image processing, using geometric algebra. This is achieved using a compact representation of vectors within dimensional space. Geometric Algebra (GA) is a preferred framework for signal representation and image representation. In this context the R, G, B color channels are not defined separately but as a single entity. As GA provides a rich set of operations, the signal and image processing operations becomes straightforward and the algorithms intuitive. From the experiments described in this paper, it is also possible to conclude that the convolution operation with the rotor masks within GA belong to a class of linear vector filters and can be applied to image or speech signals. The usefulness of the introduced approach has been demonstrated by analyzing and implementing two different types of edge detection schemes
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