Intensity Variations of H Alpha and N II 6 583 A Lines in the Night Sky Spectrum

Intensity variations of H alpha and N II 6 583 A lines in night sky spectru

Excavation to storytelling: Perspectives from archaeological heritagescapes in Sweden

Recent research has revealed that interdisciplinary work combining archaeological and heritage practice continues to be limited by enduring assumptions separating the two fields. Traditional structures and institutional barriers make it difficult to break away from what is expected in order to explore what is possible in what archaeologists and heritage practitioners ‘do’. Though archaeologists play an integral role in the discovery and interpretation of the past—providing the foundation for the heritage-making process, there is often a gap between scientific dissemination of archaeological findings and the interpretation and communication of these findings as heritage. We therefore position storytelling as a key to bridging the divide between archaeological and heritage practice. Offering perspectives from archaeological and heritage practices in Sweden, we argue that a renewed focus on storytelling creates more dynamic and collaborative pathways to interpret, communicate and experience archaeological heritagescapes

An Approximation Algorithm for Distance-Constrained Vehicle Routing on Trees

In the Distance-constrained Vehicle Routing Problem (DVRP), we are given a graph with integer edge weights, a depot, a set of $n$ terminals, and a distance constraint $D$. The goal is to find a minimum number of tours starting and ending at the depot such that those tours together cover all the terminals and the length of each tour is at most $D$. The DVRP on trees is of independent interest, because it is equivalent to the virtual machine packing problem on trees studied by Sindelar et al. [SPAA'11]. We design a simple and natural approximation algorithm for the tree DVRP, parameterized by $\varepsilon >0$. We show that its approximation ratio is $\alpha + \varepsilon$, where $\alpha \approx 1.691$, and in addition, that our analysis is essentially tight. The running time is polynomial in $n$ and $D$. The approximation ratio improves on the ratio of 2 due to Nagarajan and Ravi [Networks'12]. The main novelty of this paper lies in the analysis of the algorithm. It relies on a reduction from the tree DVRP to the bounded space online bin packing problem via a new notion of reduced length

Characterization of Prototype Superfluid Helium Safety Relief Valves for the LHC Magnets

The Large Hadron Collider (LHC) at CERN will use high field superconducting magnets operating in pressurized superfluid helium (He II) at 1.9 K. Cold safety valves, with their inlet in direct contact with the He II bath, will be required to protect the cold masses in case of a magnet resistive transition. In addition to the safety function, the valves must limit their conduction heat load to the He II to below 0.3 W and limit their mass leakage when closed to below 0.01 g/s at 1.9 K with 100 mbar differential pressure. The valves must also have a high tolerance to contaminating particles in the liquid helium. The compliance with the specified performance is of crucial importance for the LHC cryogenic operation. An extensive test program is therefore being carried out on prototype industrial valves produced by four different manufacturers. The behavior of these valves has been investigated at room temperature and at 77 K. Precise heat load and mass leak measurements have been performed on a dedicated test facility at superfluid helium temperature. Results of cold and warm tests performed on as-delivered valves are presented

Resistance of LHC main bus bar splices at room temperature and at 77.4 K

As part of the quality control the resistance of newly produced LHC main bus bar splices is now routinely measured at room temperature (RT) in order to conclude on the electrical continuity of the bus bar stabiliser across the splice under operating conditions. In this note we present splice resistance measurements that have been performed at RT and in liquid nitrogen (LN) in the CERN Cryolab with “ideal” splices (represented by continuous dipole and quadrupole bus bars), and with dipole and quadrupole splices with different defects, which cause an additional RT splice resistance of up to 60 µΩ. The RT resistance (RRT) results obtained with the Cryolab set-up are compared to the calculated resistance values and with the so-called R-8 and R-16 resistance results, as they are measured in the LHC tunnel with a Digital Low Resistance Ohmmeter with a voltage tap distance of 8 cm or 16 cm. The RT to LN resistance ratio has been determined for all splices in order to study the influence of the resistance of the splice contact surfaces on the overall splice resistance

Vieillevigne – Le Pâtis (tranche 1A)

Le projet d’extension de la carrière du Pâtis à Vieillevigne, exploitée par Carrières et Matériaux du Grand Ouest, a motivé la réalisation d’un diagnostic archéologique puis d’une fouille préventive couvrant une superficie de près de 2 ha. Elle a permis d’étudier environ 200 structures archéologiques se rapportant à plusieurs phases d’occupation échelonnées entre le second âge du Fer et l’époque contemporaine (fig. 1). Fig. 1 – Plan général de l’opération DAO : Y. Dufay-Garel (Éveha). La pri..

A Large-scale Test Facility for Heat Load Measurements down to 1.9 K

Laboratory-scale tests aimed at minimizing the thermal loads of the LHC magnet cryostat have gone along with the development of the various mechanical components. For final validation of the industrial design with respect to heat inleaks between large surfaces at different temperatures, a full-scale test cryostat has been constructed. The facility reproduces the same pattern of temperature levels as the LHC dipole cryostat, avoiding the heat inleaks from local components like supports and feedthroughs and carefully minimizing fringe effects due to the truncated geometry of the facility with respect to the LHC cryostats serial layout. Thermal loads to the actively cooled radiation screen, operated between 50 K and 65 K, are measured by enthalpy difference along its length. At 1.9 K, the loads are obtained from the temperature difference across a superfluid helium exchanger. On the beam screen, the electrical power needed to stabilize the temperature at 20 K yields a direct reading of the heat losses. Precise in-situ calibration is achieved by subcooling the thermal screen, thereby zeroing radiative heat loads. Minimizing fringe effects has been rewarded by a high precision measurement, yielding one of the more accurate quantifications to date of an industrial application of MLI. The influence of possible openings in the thermal screen is monitored both at the 1.9 K bath and with a radiation sensitive bolometer

Réponse au prétendu Démophile ou les calomniés soussignés au calomniateur pseudonyme

Polémique contre un pamphlet signé Démophile, accusant des éléments genevois et lausannois d'intrigues politiques en Valais