On the Density of Coprime m-tuples over Holomorphy Rings

Let $\mathbb F_q$ be a finite field, $F/\mathbb F_q$ be a function field of genus $g$ having full constant field $\mathbb F_q$, $\mathcal S$ a set of places of $F$ and $H$ the holomorphy ring of $\mathcal S$. In this paper we compute the density of coprime $m$-tuples of elements of $H$. As a side result, we obtain that whenever the complement of $\mathcal S$ is finite, the computation of the density can be reduced to the computation of the $L$-polynomial of the function field. In the rational function field case, classical results for the density of coprime $m$-tuples of polynomials are obtained as corollaries.Comment: To appear in International Journal of Number Theor

A stop-start study of solid propellants Final report

Thermal properties and chemical kinetics of solid phase in combustion process of ammonium perchlorate propellants during steady state and transient pressure condition

Experimental comparison of micro-scaled plate-fins and pin-fins under natural convection

This is the final version of the article. Available from the publisher via the DOI in this record.The present work analyses, for the first time, the heat transfer from pin micro-fins. The scope of the present paper is comparing thermal performance of plate micro-fin and pin micro-fin arrays under natural convection conditions in air. Two fin geometries are considered: plate and pin fin arrays with the same thermal exchanging surface are tested. The investigation shows that the pin micro-fins can improve the thermal performance compared to plate micro-fin arrays. Indeed, pin micro-fins are found to have higher heat transfer coefficients and lower thermal resistances, as well as a better material usage. This makes pin micro-fins able to achieve both thermal enhancement and weight reduction. The radiative heat transfer is calculated: a new model to determine the radiative view factors of pin fins is proposed and is used in the analysis. The effect of the orientation is considered as well.The financial support provided by the EPSRC-DST through the BioCPV project (Ref No: EP/J000345/1) is duly acknowledge

Assessment of Posidonia oceanica (L.) Delile conservation status by standard and putative approaches: the case study of Santa Marinella meadow (Italy, W Mediterranean)

The conservation status of the Posidonia oceanica meadow at Santa Marinella (Rome) was evaluated through both standard (bed density, leaf biometry, "A" coefficient, Leaf Area Index, rhizome production) and biochemical/genetic approaches (total phenol content and Random Amplified Polymorphic DNA marker). The bio-chemical/genetic results are in agreement with those obtained by standard approaches. The bed under study was ranked as a disturbed one, due to its low density, and high heterogeneity in leaf biometry, LAI values, "A" coefficient and primary production. This low quality ranking is confirmed by both mean phenol content in plants, quite high and scattered, and by the low genetic variability in the meadow, with a very high similarity of specimen at a local scale. Hence, these two putative approaches clearly identify the endangered conservation status of the meadow. They link plant biodiversity and ecophysiology to ecosystem 'health'. Furthermore, they are repeatable and standardizable and could be usefully introduced in meadows monitoring to check environmental quality

Plate Micro-Fins in Natural Convection: Experimental Study on Thermal Effectiveness and Mass Usage

This is the author accepted manuscript. The final version is available from the publisher.International Conference on Polygeneration 2015 (ICP 2015), Chennai, India, 18-20 February 2015Every year, micro-technologies are gaining more attention among researchers and industries. Although they are already applied for cooling purposes in several installations, the researches on the thermal performance of micro-fins in natural convective conditions are yet limited. The correlations between heat transfer coefficients and geometry have already been investigated. The present study merges the results of an original experimental investigation with the data available in literature, in order to give an overview of the behavior of micro-fins in terms of different heat sink metrics: the fin effectiveness and the mass specific heat transfer coefficient. The introduction of micro-fins is found not to be always beneficial in terms of heat transfer, although always positive in terms of the material usage and can be considered advantageous in those applications that requires a minimized weight of the heat sinks.The financial support provided by the EPSRC-DST through the BioCPV project is duly acknowledged

Plate micro-fins in natural convection: an opportunity for passive concentrating photovoltaic cooling

This is the final version of the article. Available from Elsevier via the DOI in this record.70th Conference of the Italian Thermal Machines Engineering Association, ATI2015The raise in temperature is a non-negligible issue for concentrating photovoltaics (CPV), where the sunlight is concentrated up to thousands of times and a large amount of heat is collected on the solar cells. Micro-fins have been identified as one of the most promising solution for CPV cooling: despite its potentials, the number of publications on this subject is still limited. The present paper resumes the state-of-the-art of the research on micro-fins, in order to identify the most convenient fin geometry for CPV applications. The results of the investigation conducted in this work show that, compared to a conventional heat sink, micro-fins can improve the thermal performance and, at the same time, lower the weight of a system. For this reason, they are particularly beneficial for tracked systems, such as CPV, where a reduced weight means a reduced load for the tracker. The heat transfer coefficients measured through an experimental setup are used to predict the performance of a micro-finned CPV system in natural convection: an optimized fin array is found able to enhance the mass specific power up to 50% compared to an unfinned surface.This work was financially supported by the EPSRC-DST funded BioCPV project (EP/J000345/1)

A Single Atom Transistor in a 1D Optical Lattice

We propose a scheme utilising a quantum interference phenomenon to switch the transport of atoms in a 1D optical lattice through a site containing an impurity atom. The impurity represents a qubit which in one spin state is transparent to the probe atoms, but in the other acts as a single atom mirror. This allows a single-shot quantum non-demolition measurement of the qubit spin.Comment: RevTeX 4, 5 Figures, 4 Page

Quantum Communication in Spin Systems With Long-Range Interactions

We calculate the fidelity of transmission of a single qubit between distant sites on semi-infinite and finite chains of spins coupled via the magnetic dipole interaction. We show that such systems often perform better than their Heisenberg nearest-neighbour coupled counterparts, and that fidelities closely approaching unity can be attained between the ends of finite chains without any special engineering of the system, although state transfer becomes slow in long chains. We discuss possible optimization methods, and find that, for any length, the best compromise between the quality and the speed of the communication is obtained in a nearly uniform chain of 4 spins.Comment: 15 pages, 8 eps figures, updated references, corrected text and corrected figs. 1, 4 and