225 research outputs found
Multi-scale analysis of timber framed structures filled with earth and stones
This paper deals with the seismic analysis of timber framed houses filled by stones and earth mortar using a multi-scale approach going from the cell to the wall and then to the house. At the scale of the elementary cells, experimental results allow fitting the parameters of a new versatile hysteretic law presented herein through the definition of a macro-element. Then, at the scale of wall, the numerical simulations are able to predict its behavior under quasi-static cyclic loading and is compared to experimental results allowing validating the macro-element model
Laser-driven plasma waves in capillary tubes
The excitation of plasma waves over a length of up to 8 centimeters is, for
the first time, demon- strated using laser guiding of intense laser pulses
through hydrogen filled glass capillary tubes. The plasma waves are diagnosed
by spectral analysis of the transmitted laser radiation. The dependence of the
spectral redshift, measured as a function of filling pressure, capillary tube
length and incident laser energy, is in excellent agreement with simulation
results. The longitudinal accelerating field inferred from the simulations is
in the range 1 -10 GV/m
Recommended from our members
The sugar content of children’s and lunchbox beverages sold in the UK before and after the soft drink industry levy
Background: Childhood obesity is associated with an increased intake of sugary soft drinks and juice drinks. The aims of this study were (1) to report the sugar and energy content in commercial fruit juice (FJ), juice drinks (JD) and smoothies (S) specifically targeted at children in the UK, (2) to identify beverages liable for the Soft Drinks Industry Levy (SDIL) and (3) to compare the amount of sugar in these beverages before and after the levy.
Methods: The beverages were retrieved using the online shopping tool my Supermarket, websites of nine major supermarket in the UK and manufacturers webpages. Comparisons of sugar content were taken before and after the introduction of the SDIL.
Results: 131 FJJDS fulfilled the inclusion criteria. The mean sugar content of all the beverages was 6.3g±4.5/100mL. There was large variation in the sugar content from 0.1g/100mL to 15.2g/100mL, with smoothies found to contain the most sugar (11.55±1.62 g/mL). The beverages were reanalysed in September 2018 to determine their eligibility for the SDIL. Of the 131 products only 7 JD were eligible for the levy. Four of these beverages had reformulated their ingredients since the initial analysis resulting in a sugar content of <5g/100mL.
Conclusions: The majority of the beverages targeted at children and children’s lunch boxes were not eligible for the SDIL. This study suggests the necessity to adapt the SDIL to include all FJJDS aimed at children as the total sugar content of these beverages are still above the recommended quantities for this age group
Seismic behaviour of traditional timber frame walls: experimental results on unreinforced walls
Timber frame buildings are well known as an efficient seismic resistant structure
and they are used worldwide. Moreover, they have been specifically adopted in codes and
regulations during the XVIII and XIX centuries in the Mediterranean area. These structures
generally consist of exterior masonry walls with timber elements embedded which tie the
walls together and internal walls which have a timber frame with masonry infill and act as
shearwalls. In order to preserve these structureswhich characterizemany cities in theworld it
is important to better understand their behaviour under seismic actions. Furthermore, historic
technologies could be used even in modern constructions to build seismic resistant buildings
using more natural materials with lesser costs. Generally, different types of infill could be
applied to timber frame walls depending on the country, among which brick masonry, rubble
masonry, hay and mud. The focus of this paper is to study the seismic behaviour of the walls
considering different types of infill, specifically: masonry infill, lath and plaster and timber
frame with no infill. Static cyclic tests have been performed on unreinforced timber frame
walls in order to study their seismic capacity in terms of strength, stiffness, ductility and
energy dissipation. The tests showed how in the unreinforced condition, the infill is able to
guarantee a greater stiffness, ductility and ultimate capacity of the wall.The authors would like to acknowledge Eng. Filipe Ferreira and A.O.F. (Augusto Oliveira Ferreira &
C Lda.) for their expertise and collaboration in the construction of the wall specimens.
The first author would also like to acknowledge the Portuguese Science and Technology
Foundation (FCT) for its financial support through grant SFRH / BD / 61908 / 2009
High Current, High frequency ECRIS development program for LHC heavy ion beam application
A research program with the aim of producing pulsed currents with hitherto unequalled intensity of Pb27+, with length and repetition ratecompatible with those desired by CERN (1 mAe / 400 ms / 10 Hz in the context of future heavy ion collisions at LHC) is organised in acollaboration between CERN/GSI/CEA-Grenoble and IN2P3-ISNG.Two main experimental programs will be carried out : (i) tests with the LNS-Catania team on the SERSE superconducting source with a 28 GHzgyrotron, (ii) tests on a non-superconducting source (new source at Grenoble) with a 28 GHz gyrotron. For this purpose CEA/DRFMC hasborrowed from CEA a 28 GHz - 10 kW gyrotron transmitter.The project includes also the construction of a source body, by ISNG, with conventional coils and permanent magnets for working at the frequencyof about 28 GHz and biased up to 60 kV. This source called PHOENIX will run on a test bench at ISN. PHOENIX is an improvement of thepresent ECR4-14.5 GHz/CERN source, having a mirror ratio R=2 at 14.5 GHz, and R=1.7 at 28 GHz (possibly reaching 2.1 T on the axis of thesource), and with a plasma volume up to 2.5 larger.Experiments at 28 GHz will be performed on the SERSE source in Catania at INFN/LNS where both the axial and the hexapolar fields will bevaried so that the mirror ratio is continuously varied up to R=1.6 ; the SERSE source will be also operated at lower magnetic fields such as thosewhich can be produced by conventional magnets (less than 2 T axial field at injection - far from the 28 GHz High-B mode)
- …