105 research outputs found
Experimental investigations on the fatigue resistance of automatically welded tubular X-joints for jacket support structures
The development within the offshore wind sector towards more powerful turbines combined with increasing water depth for new wind parks is challenging both the designer as well as the manufacturer of bottom fixed support structures. Besides XL-monopiles, the market developed an innovative and economic jacket support structure which is based on automatically manufactured tubular joints combined with standardized pipes. Besides the improvements for a serial manufacturing process the automatically welded tubular joints show a great potential in terms of fatigue resistance e.g. due to a smooth weld geometry without sharp notches. However, these benefits are not considered yet within the fatigue design process of automatically manufactured jacket substructures according to current standards due to the lack of suitable S-N curves. Therefore, 32 axial fatigue tests on single and double-sided automatically welded tubular X-joints have been performed to determine a new hot spot stress related S-N curve. Based on these constant amplitude fatigue tests a new S-N curve equal to a FAT 126 curve was computed which implicitly includes the benefits of the automatically welding procedure. © Published under licence by IOP Publishing Ltd
Die Funktion und Bedeutung Fritz Hipplers fĂŒr das Filmschaffen im âDritten Reichâ
Im Mittelpunkt der Dissertation steht Fritz Hippler, der nationalsozialistische Filmemacher und Reichsfilmintendant. Die deutliche Konzentration auf seine Person bietet die Möglichkeit, den Einsatz von Propaganda als Vermittlungskanal faschistischer Ăsthetik im Dritten Reich zu erlĂ€utern. An Hippler lĂ€sst sich zudem nachvollziehen, wie rasch die nationalsozialistischen Funktionseliten die Macht des Mediums Film erkannt und fĂŒr ihre Zwecke genutzt haben. UnerlĂ€sslich fĂŒr das VerstĂ€ndnis des Hipplerschen Werks ist eine deutliche Unterscheidung zwischen direkter und indirekter filmischer Propaganda. Diese vermochte der talentierte Filmemacher je nach Bedarf einzusetzen. Zudem changiert der Grad des Antisemitismus in seinen Filmen. WĂ€hrend etwa die Kriegsdokumentationen kaum Judenhass abbilden, strotzt sein Hauptwerk, der âDer ewige Judeâ, vor Antisemitismus und rassistischer Agitation. Nicht von ungefĂ€hr gilt âDer ewige Judeâ gleichsam als filmisches Begleitprogramm zum Holocaust
In-situ characterization of the Hamamatsu R5912-HQE photomultiplier tubes used in the DEAP-3600 experiment
The Hamamatsu R5912-HQE photomultiplier-tube (PMT) is a novel high-quantum
efficiency PMT. It is currently used in the DEAP-3600 dark matter detector and
is of significant interest for future dark matter and neutrino experiments
where high signal yields are needed.
We report on the methods developed for in-situ characterization and
monitoring of DEAP's 255 R5912-HQE PMTs. This includes a detailed discussion of
typical measured single-photoelectron charge distributions, correlated noise
(afterpulsing), dark noise, double, and late pulsing characteristics. The
characterization is performed during the detector commissioning phase using
laser light injected through a light diffusing sphere and during normal
detector operation using LED light injected through optical fibres
A new and sensitive reaction rate method for spectrophotometric determination of trace amounts of thiourea in different water samples based on an induction period
BACKGROUNDAgrilus bigutattus (Fabricius) is a forest pest of increasing importance in the United Kingdom. The larvae damage weakened native oaks and are thought to contribute to premature tree death. Suspected links with acute oak decline (AOD) are not yet confirmed, but AOD-predisposed trees appear to become more susceptible to A. biguttatus attack. Thus, management may be necessary for control of this insect. To explore the possibility of monitoring beetle populations by baited traps, the host tree volatiles regulating A. biguttatus-oak interactions were studied. RESULTSBiologically active volatile organic compounds in dynamic headspace extracts of oak foliage and bark were identified initially by coupled gas chromatography-electroantennography (GC-EAG) and GC-mass spectrometry (GC-MS), and the structures were confirmed by GC coinjection with authentic compounds. Of two synthetic blends of these compounds comprising the active leaf volatiles, the simpler one containing three components evoked strongly positive behavioural responses in four-arm olfactometer tests with virgin females and males, although fresh leaf material was more efficient than the blend. The other blend, comprising a five-component mixture made up of bark volatiles, proved to be as behaviourally active for gravid females as bark tissue. CONCLUSIONSThese initial results on A. biguttatus chemical ecology reveal aspects of the role of attractive tree volatiles in the host-finding of beetles and underpin the development of semiochemically based surveillance strategies for this forest insect. (c) 2015 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry
Determining the bubble nucleation efficiency of low-energy nuclear recoils in superheated CF dark matter detectors
The bubble nucleation efficiency of low-energy nuclear recoils in superheated
liquids plays a crucial role in interpreting results from direct searches for
weakly interacting massive particle (WIMP) dark matter. The PICO Collaboration
presents the results of the efficiencies for bubble nucleation from carbon and
fluorine recoils in superheated CF from calibration data taken with 5
distinct neutron spectra at various thermodynamic thresholds ranging from 2.1
keV to 3.9 keV. Instead of assuming any particular functional forms for the
nuclear recoil efficiency, a generalized piecewise linear model is proposed
with systematic errors included as nuisance parameters to minimize
model-introduced uncertainties. A Markov-Chain Monte-Carlo (MCMC) routine is
applied to sample the nuclear recoil efficiency for fluorine and carbon at 2.45
keV and 3.29 keV thermodynamic thresholds simultaneously. The nucleation
efficiency for fluorine was found to be for nuclear recoils of
3.3 keV (3.7 keV) at a thermodynamic Seitz threshold of 2.45 keV (3.29 keV),
and for carbon the efficiency was found to be for recoils of
10.6 keV (11.1 keV) at a threshold of 2.45 keV (3.29 keV). Simulated data sets
are used to calculate a p-value for the fit, confirming that the model used is
compatible with the data. The fit paradigm is also assessed for potential
systematic biases, which although small, are corrected for. Additional steps
are performed to calculate the expected interaction rates of WIMPs in the
PICO-60 detector, a requirement for calculating WIMP exclusion limits.Comment: 17 pages, 22 figures, 5 table
Search for inelastic dark matter-nucleus scattering with the PICO-60 CFI and CF bubble chambers
PICO bubble chambers have exceptional sensitivity to inelastic dark
matter-nucleus interactions due to a combination of their extended nuclear
recoil energy detection window from a few keV to (100 keV) or more and the
use of iodine as a heavy target. Inelastic dark matter-nucleus scattering is
interesting for studying the properties of dark matter, where many theoretical
scenarios have been developed. This study reports the results of a search for
dark matter inelastic scattering with the PICO-60 bubble chambers. The analysis
reported here comprises physics runs from PICO-60 bubble chambers using
CFI and CF. The CFI run consisted of 36.8 kg of
CFI reaching an exposure of 3415 kg-day operating at thermodynamic
thresholds between 7 and 20 keV. The CF runs consisted of 52 kg of
CF reaching exposures of 1404 kg-day and 1167 kg-day running at
thermodynamic thresholds of 2.45 keV and 3.29 keV, respectively. The analysis
disfavors various scenarios, in a wide region of parameter space, that provide
a feasible explanation of the signal observed by DAMA, assuming an inelastic
interaction, considering that the PICO CFI bubble chamber used iodine as
the target material.Comment: 7 pages, 3 figure
Electromagnetic backgrounds and potassium-42 activity in the DEAP-3600 dark matter detector
See full article for abstrac
Constraints on dark matter-nucleon effective couplings in the presence of kinematically distinct halo substructures using the DEAP-3600 detector
DEAP-3600 is a single-phase liquid argon detector aiming to directly detect
Weakly Interacting Massive Particles (WIMPs), located at SNOLAB (Sudbury,
Canada). After analyzing data taken during the first year of operation, a null
result was used to place an upper bound on the WIMP-nucleon spin-independent,
isoscalar cross section. This study reinterprets this result within a
Non-Relativistic Effective Field Theory framework, and further examines how
various possible substructures in the local dark matter halo may affect these
constraints. Such substructures are hinted at by kinematic structures in the
local stellar distribution observed by the Gaia satellite and other recent
astronomical surveys. These include the Gaia Sausage (or Enceladus), as well as
a number of distinct streams identified in recent studies. Limits are presented
for the coupling strength of the effective contact interaction operators
, , , , and
, considering isoscalar, isovector, and xenonphobic
scenarios, as well as the specific operators corresponding to millicharge,
magnetic dipole, electric dipole, and anapole interactions. The effects of halo
substructures on each of these operators are explored as well, showing that the
and operators are particularly sensitive to the
velocity distribution, even at dark matter masses above 100 GeV/
First direct detection constraints on Planck-scale mass dark matter with multiple-scatter signatures using the DEAP-3600 detector
Dark matter with Planck-scale mass (similar or equal to 10(19) GeV/c(2)) arises in well-motivated theories and could be produced by several cosmological mechanisms. A search for multiscatter signals from supermassive dark matter was performed with a blind analysis of data collected over a 813 d live time with DEAP-3600, a 3.3 t single-phase liquid argon-based detector at SNOLAB. No candidate signals were observed, leading to the first direct detection constraints on Planck-scale mass dark matter. Leading limits constrain dark matter masses between 8.3 x 10(6) and 1.2 x 10(19) GeV/c(2), and Ar-10-scattering cross sections between 1.0 x 10(-23) and 2.4 x 10(-18) cm(2). These results are interpreted as constraints on composite dark matter models with two different nucleon-to-nuclear cross section scalings
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