863 research outputs found
Thermal and Irradiation Creep Behavior of a Titanium Aluminide in Advanced Nuclear Plant Environments
Titanium aluminides are well-accepted elevated temperature materials. In conventional applications, their poor oxidation resistance limits the maximum operating temperature. Advanced reactors operate in nonoxidizing environments. This could enlarge the applicability of these materials to higher temperatures. The behavior of a cast gamma-alpha-2 TiAl was investigated under thermal and irradiation conditions. Irradiation creep was studied in beam using helium implantation. Dog-bone samples of dimensions 10Ă2Ă0.2mm3 were investigated in a temperature range of 300°C to 500°C under irradiation, and significant creep strains were detected. At temperatures above 500°C, thermal creep becomes the predominant mechanism. Thermal creep was investigated at temperatures up to 900°C without irradiation with samples of the same geometry. The results are compared with other materials considered for advanced fission applications. These are a ferritic oxide-dispersion-strengthened material (PM2000) and the nickel-base superalloy IN617. A better thermal creep behavior than IN617 was found in the entire temperature range. Up to 900°C, the expected 104 hour stress rupture properties exceeded even those of the ODS alloy. The irradiation creep performance of the titanium aluminide was comparable with the ODS steels. For IN617, no irradiation creep experiments were performed due to the expected low irradiation resistance (swelling, helium embrittlement) of nickel-base alloy
Spectroscopy of D-type asteroids
We have performed a spectroscopic survey of 19 D-type asteroids. Comparison with previous photometry shows excellent agreement. Although the majority have similar colors to cometary nuclei, no cometary emission bands were present in any of the spectra. Absorption bands sporadically appearing were apparently due to stellar objects, and no features inherent to the asteroids were observed
Design for me?
In this paper, as a generative contrast to the notion of design âfor allâ, we present and discuss the potential benefits of a design âfor meâ approach, where the design process from the starts from, and initially is targeted at, just one person. Given many things developed for a user group or a constructed average user, in this text we describe starting from design for a single user as an alternative approach for achieving useful and useworthy designs. We provide an example from the development of an assistive device as the starting point and discuss how and why this alternative approach should be of interest for everyone interested in usability
Development of Norway spruce, Douglas fir, beech and Scots pine with a shelter of hybrid larch
"Development of Norway spruce, Douglas fir beech and Scots pine with a larch
shelter wood" is a report written by Per-Olof Magnusson. The thesis is a
compulsory part of forest engineer program at "SkogsmÀstarskolan", SLU,
Skinnskatteberg, Sweden.
The purpose of this report is to describe and evaluate an experiment with hybrid
larch (Larix x eurolepis) as shelter wood, and different tree species growth and
survival depending on the density of the shelter wood. The experiment is
conducted by southern Swedish forest research centre, faculty of forestry, SLU in
Alnarp.
The hybrid larch ought to be an interesting alternative to birch (Betula sp.) as
shelterwood on suitable sites in southern Sweden. It outgrows both grass and
other vegetation quickly and is regarded to be a good shelter tree to shadow
tolerant tree species as beech and spruce. The timber prices is approximately the
same as for spruce, but straight, knot free wood can have same prizes as pine.
About 2000 hybrid larches per ha were planted 1974. After four thinnings and one
storm there's now standing 230 trees in the dense shelter and 145 in the sparse
shelter. Below the shelters and on one open area spruce (Picea abies) were
planted in 1990.
Due to heavy gracing a fence was built spring 1993. Beech (Fagus sylvatica),
douglas fir (Psedotsuga menziesii) and pine (Pinus sylvestris) and spruce were
planted in the tree areas, a dense shelter, a sparse shelter and an open area
adjacent to the shelters.
Since these results is based on only one experiment no final conclusions can be
made, but the results give a hint on how the different tree species react on the
shelterwood density. As expected the growth of all the different tree species
increase with lesser amount of shelter wood (Fig. 2-3).
The pines bellow the shelter woods were all killed by insects or by a combination
of competition from the shelter and insects, at an early stage.
The survival lies between 72 and 97 % for all the tree species except for the
Douglas-fir. The lowest survival for Douglas-fir was below the sparse shelter
wood (36 %). Overall it looks like the mortality is greater below the sparse shelter
wood but the most probable reason for this is that the fence on this location was
broken in a couple of places and roe deer and elk has got in and graced.
You could probably see more obvious trends of survival if the experiment had
been placed in a more frost affected area. One could also speculate if the spruce
and beech would have a greater mortality without the shelter wood since grass
grew thick amongst the plants.Syftet med detta examensarbete Àr att beskriva och redovisa ett försök med
hybridlÀrk som skÀrmtrÀd över planterad tall, gran, bok och douglasgran. samt att
redovisa de olika trÀdslags tillvÀxt och överlevnad i olika tÀta skÀrmar.
HybridlÀrken borde vara ett intressant alternativ som skÀrmtrÀd pÄ lÀmpliga
marker i södra Sverige. Den vÀxer snabbt ifrÄn bÄde ogrÀs och lövsly och anses
vara ett mycket bra amtrÀd Ät skuggtÄliga trÀdslag som bok och gran.
1974 planterades 2000 hybridlĂ€rkar per hektar pĂ„ âOD Krooks donationsâ mark i
nÀrheten av Klippan, SkÄne. Efter fyra gallringar samt tvÄ stormar Äterstod 173
respektive 147 trÀd per hektar pÄ tvÄ försöksomrÄden. Under dessa skÀrmar, samt
pÄ en kalyta planterades gran (kallad bef. gran i texten). DÄ dessa granar betades
kraftigt sattes ett viltstÀngsel upp vÄren 1993, samtidigt planterades bok,
douglasgran, tall och en ny generation gran.
TillvÀxt, skadefrekvens och dödlighet bland dessa plantor har mÀtts kontinuerligt
och har i hÀr sammanstÀllts och utvÀrderats.
Alla tallplantor under de bÄda skÀrmarna har dött, dels pÄ grund av insekter,
troligen lÀrksÀcksmalen, som fallit ner frÄn lÀrkarna, samt pÄ grund av kraftig
konkurrens frĂ„n krustĂ„tel. Ăverlevnaden bland de andra trĂ€dslagen ligger pĂ„
mellan 56 och 97 % (tabell 1). Under den glesa skÀrmen Àr överlevnaden lÀgst,
men det beror troligtvis pÄ att viltsÀngslet vid nÄgra tillfÀllen varit sönder hÀr sÄ
att viltet har haft det lÀttare att komma in hÀr. I kontrast till detta har en nÄgot
större andel sjÀlvföryngrade plantor lyckats etablera sig under den glesa skÀrmen.
De sjÀlvföryngrade plantorna Àr av andra trÀdslag och sÄ smÄ att de sÀllan
kommer att ingÄ i framtidsbestÄndet.
I tabell 1 ser skadefrekvensen hög ut men de flesta av skadorna Àr gamla eller
relativt ofarliga och resulterar i de flesta fall i en mindre tillvÀxtförlust.
HöjdtillvÀxten ökar markant utan skÀrm. Detta gÀller i högre grad för
barrplantorna Àn för bokplantorna.
Hade försöket placerats i ett mer frostdrabbat omrÄde hade man troligtvis sett
tydligare trender för överlevnad, man kan ocksÄ spekulera ifall sÄ mÄnga gran och
bokplantor hade överlevt utan skÀrmarna eftersom grÀset vÀxte tÀtt mellan
plantorna.
SkÀrmar av lÀrk (hybridlÀrk) med de tÀtheter som anvÀnts i försöket i Vedby
(grundyta pÄ mellan 10 och 15 m2/ha) passar bra över bok. För douglasgran har
höjdtillvÀxten sÀnkts med ca 25% och för gran ca 40% jÀmfört med kalytan. Att
plantera tall under skÀrm av lÀrk avrÄdes bestÀmt ifrÄn
Optical and mechanical properties of amorphous Mg-Si-O-N thin films deposited by reactive magnetron sputtering
In this work, amorphous thin films in Mg-Si-O-N system were prepared in order
to investigate the dependence of optical and mechanical properties on Mg
composition. Reactive RF magnetron co-sputtering from magnesium and silicon
targets were used for the deposition of Mg-Si-O-N thin films. Films were
deposited on float glass, silica wafers and sapphire substrates in an Ar, N2
and O2 gas mixture. X-ray photoelectron spectroscopy, atomic force microscopy,
scanning electron microscopy, spectroscopic ellipsometry, and nanoindentation
were employed to characterize the composition, surface morphology, and
properties of the films
Philosophy and updating of the asteroid photometric catalogue
The Asteroid Photometric Catalogue now contains photometric lightcurves for 584 asteroids. We discuss some of the guiding principles behind it. This concerns both observers who offer input to it and users of the product
Blood alcohol concentration at 0.06 and 0.10% causes a complex multifaceted deterioration of body movement control.
Alcohol-related falls are recognized as a major contributor to the occurrence of traumatic brain injury. The control of upright standing balance is complex and composes of contributions from several partly independent mechanisms such as appropriate information from multiple sensory systems and correct feedback and feed forward movement control. Analysis of multisegmented body movement offers a rarely used option for detecting the fine motor problems associated with alcohol intoxication. The study aims were to investigate whether (1) alcohol intoxication at 0.06 and 0.10% blood alcohol concentration (BAC) affected the body movements under unperturbed and perturbed standing; and (2) alcohol affected the ability for sensorimotor adaptation. Body movements were recorded in 25 participants (13 women and 12 men, mean age 25.1 years) at five locations (ankle, knee, hip, shoulder, and head) during quiet standing and during balance perturbations from pseudorandom pulses of calf muscle vibration over 200s with eyes closed or open. Tests were performed at 0.00, 0.06, and 0.10% BAC. The study revealed several significant findings: (1) an alcohol dose-specific effect; (2) a direction-specific stability decrease from alcohol intoxication; (3) a movement pattern change related to the level of alcohol intoxication during unperturbed standing and perturbed standing; (4) a sensorimotor adaptation deterioration with increased alcohol intoxication; and (5) that vision provided a weaker contribution to postural control during alcohol intoxication. Hence, alcohol intoxication at 0.06 and 0.10% BAC causes a complex multifaceted deterioration of human postural control
Police officer involved shootings â retrospective study of situational characteristics
The study analyzed the situational characteristics of 112 incidents where police used firearms to handle high threat situations. Most shooting incidents emanated from usually uneventful tasks, e.g., handling burglaries or disturbances. The assailants were commonly armed with firearms (26%), sharp (27%) or blunt objects (10%). The incidents were regularly short-lasting (in 39% were shots fired â€3 s from threat emerged) and occurred at short distances (in 42% at distances â€3 m). Predominantly, the first responders had to address the situation and did so with warning shots or, equally common, with fire-for-effect shots (40%) or a combination thereof. Psychological stress was manifested as feelings of panic at some point and as motor skill alterations, e.g., firing without using sights and with one hand only. Analysis of these incidents shows that all field duty police officers should receive training in handling potentially life-threatening, sudden, close-range attacks
Lipocalin-2 is associated with FGF23 in WNT1 and PLS3 osteoporosis
BackgroundThe pathogenic mechanisms of early-onset osteoporosis caused by WNT1 and PLS3 mutations are incompletely understood and diagnostic biomarkers of these disorders are limited. Recently, lipocalin-2 has been recognized as an osteokine involved in bone development and homeostasis. However, the role of lipocalin-2 in WNT1 and PLS3 osteoporosis is unknown. ObjectiveWe aimed to investigate if plasma lipocalin-2 could be utilized as a biomarker for WNT1 and PLS3 osteoporosis and to evaluate the association between lipocalin-2 and other parameters of bone metabolism. MethodsWe measured plasma lipocalin-2 in 17 WNT1 and 14 PLS3 mutation-positive patients and compared them to those of 34 mutation-negative (MN) healthy subjects. We investigated possible associations between lipocalin-2 and several bone biomarkers including collagen type I cross-linked C-telopeptide (CTX), alkaline phosphatase (ALP), type I procollagen intact N-terminal propeptide (PINP), intact and C-terminal fibroblast growth factor 23 (FGF23), dickkopf-1 (DKK1) and sclerostin as well as parameters of iron metabolism (iron, transferrin, transferrin saturation, soluble transferrin receptor and ferritin). ResultsWe found no differences in plasma lipocalin-2 levels in WNT1 or PLS3 patients compared with MN subjects. However, lipocalin-2 was associated with C-terminal FGF23 in WNT1 patients (r=0.62; p=0.008) and PLS3 patients (r=0.63, p=0.017), and with intact FGF23 in PLS3 patients (r=0.80; pPeer reviewe
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