6,324 research outputs found
Увага! Kорисна інформація
Знаковою для геологічної спільноти України стала 71 конференція Європейської асоціації геовчених та інженерів (EAGE), що відбулася в червні 2009 р. в Амстердамі – Королівство Нідерланди
Landscape ecological Decision & Evaluation Support System LEDESS : users guide
To understand the basic strategies in nature development, it is necessary to examine existing plans and schemes in order to reveal and clarify underlying concepts. Two questions are crucial here: what is the ecological objective, and what is the spatial strategy? The first question is related to the level of the ecosystem. With different types of nature management, different ecosystems can develop at the same site. Nature policy decides which system is to be developed. The second question is related to the landscape as a whole, the spatial pattern of ecosystems. It is taken into account that other activities, such as farming, recreation, water supply and quarrying, also require space. Nature development cannot be considered independently from those activities. Therefore, a spatial strategy is required to combine all land use functions. To find an optimal balance between the two questions, different nature development scenarios are developed
Товарная структура внешней торговли с Украиной как фактор формирования отрицательного торгового сальдо
Торгово-экономические связи между Республикой Болгарией и Украиной развиваются динамично, но объемы экспорта и импорта ниже экономических возможностей двух стран. Существенный вклад в развитие торговых отношений между Республикой Болгарией и Украиной вносят заключенные двухсторонние соглашения, увязанные с внешнеторговым режимом стран, соблюдение общих принципов международной торговли и членство стран в Организации черноморского экономического сотрудничества.Торговельно-економічні зв’язки між Республікою Болгарією і Україною розвиваються динамічно, але об’єми експорту і імпорту нижче економічних можливостей двох країн. Істотний внесок в розвиток торгових відносин між Республікою Болгарією і Україною вносять укладені двосторонні угоди, пов’язані із зовнішньоторговельним режимом країн, дотримання загальних принципів міжнародної торгівлі і членство країн до Організацій чорноморського економічного співробітництва.Trade and economic connections between Republic it is developed Bulgaria and Ukraine dynamically, but volumes of export and import below of economic feasibilities of two countries. Substantial contribution to development of pointof-sale relations between Republic Bulgaria and Ukraine is bring in the celled reciprocal contracts, tied up with the foreign trade mode of countries, observance of general principles of international trade and membership of countries in Organizations of black sea economic collaboration
Production of defect-poor nanostructured ceramics of yttria-zirconia
For the production of nanostructured ceramics of yttria-zirconia four powders differing in agglomerate strength, agglomerate size and crystallite size are compared. An ultra-fine-grained ceramic with a final density of 98% and a grain size of 0.18 μm could be produced from a hydrothermally crystallized ethanol-washed powder. The remaining porosity is caused by some residual defects which are present due to the irregular shape of the agglomerates and which cause improper die filling. A commercially available powder was also investigated. This powder consists of homogeneous porous, spherical, weak agglomerates. The resulting ceramic has a high density (≥ 99%) but cannot be obtained with ultra-fine grain size (minimum grain size is 0.3 μm). The air-crystallized ethanol-washed powder resulted, after sintering, in larger porosities. In this case the powder consists of weak and some strong agglomerates and a few defect clusters are found in the sintered ceramic which limit the maximum attainable density to 92%. The air-crystallized water-washed powder consists of agglomerates which are too strong to be fractured during compaction. The sintered ceramics contain a large amount of porosity (20%) which is attributed to the presence of inter-agglomerate pores.\u
Fast Ramping Superconducting Magnet Design Issues for Future Injector Upgrades at CERN
An upgrade of the LHC injection chain, and especially the sequence of PS and SPS, up to an extraction energy of 1Â TeV, is one of the steps considered to improve the performance of the whole accelerator complex. The magnets for this upgrade require central magnetic field from 2 T (for a PS upgrade) to 4.5 T (for an SPS upgrade), for which superconducting magnets are a candidate. Due to the fast field sweep rate of the magnets (from about 1.5 T/s to 2.5Â T/s), internal heating from eddy and persistent current effects (AC loss) must be minimized. In this paper we discuss a rationale for the design and optimization of fast ramped superconducting accelerator magnets, specifically aimed at the LHC injectors. We introduce a design parameter, the product of bore field and field ramp-rate, providing a measure of the magnet performance, and we apply it to choose the design range for a technology demonstration magnet. We finally discuss the dependence of key design parameters on the bore field and the bore diameter, to provide an approximate scaling and guidelines for critical R&D
A Multistage Stochastic Programming Approach to the Dynamic and Stochastic VRPTW - Extended version
We consider a dynamic vehicle routing problem with time windows and
stochastic customers (DS-VRPTW), such that customers may request for services
as vehicles have already started their tours. To solve this problem, the goal
is to provide a decision rule for choosing, at each time step, the next action
to perform in light of known requests and probabilistic knowledge on requests
likelihood. We introduce a new decision rule, called Global Stochastic
Assessment (GSA) rule for the DS-VRPTW, and we compare it with existing
decision rules, such as MSA. In particular, we show that GSA fully integrates
nonanticipativity constraints so that it leads to better decisions in our
stochastic context. We describe a new heuristic approach for efficiently
approximating our GSA rule. We introduce a new waiting strategy. Experiments on
dynamic and stochastic benchmarks, which include instances of different degrees
of dynamism, show that not only our approach is competitive with
state-of-the-art methods, but also enables to compute meaningful offline
solutions to fully dynamic problems where absolutely no a priori customer
request is provided.Comment: Extended version of the same-name study submitted for publication in
conference CPAIOR201
Testing Beam-Induced Quench Levels of LHC Superconducting Magnets
In the years 2009-2013 the Large Hadron Collider (LHC) has been operated with
the top beam energies of 3.5 TeV and 4 TeV per proton (from 2012) instead of
the nominal 7 TeV. The currents in the superconducting magnets were reduced
accordingly. To date only seventeen beam-induced quenches have occurred; eight
of them during specially designed quench tests, the others during injection.
There has not been a single beam- induced quench during normal collider
operation with stored beam. The conditions, however, are expected to become
much more challenging after the long LHC shutdown. The magnets will be
operating at near nominal currents, and in the presence of high energy and high
intensity beams with a stored energy of up to 362 MJ per beam. In this paper we
summarize our efforts to understand the quench levels of LHC superconducting
magnets. We describe beam-loss events and dedicated experiments with beam, as
well as the simulation methods used to reproduce the observable signals. The
simulated energy deposition in the coils is compared to the quench levels
predicted by electro-thermal models, thus allowing to validate and improve the
models which are used to set beam-dump thresholds on beam-loss monitors for Run
2.Comment: 19 page
Thinner Regions of Intracranial Aneurysm Wall Correlate with Regions of Higher Wall Shear Stress: A 7T MRI Study
BACKGROUND AND PURPOSE: Both hemodynamics and aneurysm wall thickness are important parameters in aneurysm pathophysiology. Our aim was to develop a method for semi-quantitative wall thickness assessment on in vivo 7T MR images of intracranial aneurysms for studying the relation between apparent aneurysm wall thickness and wall shear stress.
MATERIALS AND METHODS: Wall thickness was analyzed in 11 unruptured aneurysms in 9 patients who underwent 7T MR imaging with a TSE-based vessel wall sequence (0.8-mm isotropic resolution). A custom analysis program determined the in vivo aneurysm wall intensities, which were normalized to the signal of nearby brain tissue and were used as measures of apparent wall thickness. Spatial wall thickness variation was determined as the interquartile range in apparent wall thickness (the middle 50% of the apparent wall thickness range). Wall shear stress was determined by using phase-contrast MR imaging (0.5-mm isotropic resolution). We performed visual and statistical comparisons (Pearson correlation) to study the relation between wall thickness and wall shear stress.
RESULTS: 3D colored apparent wall thickness maps of the aneurysms showed spatial apparent wall thickness variation, which ranged from 0.07 to 0.53, with a mean variation of 0.22 (a variation of 1.0 roughly means a wall thickness variation of 1 voxel [0.8 mm]). In all aneurysms, apparent wall thickness was inversely related to wall shear stress (mean correlation coefficient, −0.35; P < .05).
CONCLUSIONS: A method was developed to measure the wall thickness semi-quantitatively, by using 7T MR imaging. An inverse correlation between wall shear stress and apparent wall thickness was determined. In future studies, this noninvasive method can be used to assess spatial wall thickness variation in relation to pathophysiologic processes such as aneurysm growth and rupture
Klimaat In Ruimtelijke Keuzes: Het Dialoogondersteunend Afwegingskader (DAK)
Het doel van het HSHL01 project ‘Klimaat in ruimtelijke keuzes’ is om een dialoog ondersteunend
afwegingskader (DAK) te ontwikkelen en toe te passen. Met dit afwegingskader kunnen de betrokken
partijen gezamenlijk de lange termijn effecten van klimaatverandering op het waterbeheer in een vroegtijdig
stadium en op inzichtelijke wijze meewegen in het proces van ruimtelijke planvorming. Het gaat hierbij
zowel om de locatiekeuze van ruimtelijke ontwikkelingen als de inrichting van eenmaal gekozen
woningbouwlocaties, bedrijventerreinen en glastuinbouwlocaties
Multi-parallel qPCR provides increased sensitivity and diagnostic breadth for gastrointestinal parasites of humans: field-based inferences on the impact of mass deworming
BACKGROUND: Although chronic morbidity in humans from soil transmitted helminth (STH) infections can be reduced by anthelmintic treatment, inconsistent diagnostic tools make it difficult to reliably measure the impact of deworming programs and often miss light helminth infections. METHODS: Cryopreserved stool samples from 796 people (aged 2-81 years) in four villages in Bungoma County, western Kenya, were assessed using multi-parallel qPCR for 8 parasites and compared to point-of-contact assessments of the same stools by the 2-stool 2-slide Kato-Katz (KK) method. All subjects were treated with albendazole and all Ascaris lumbricoides expelled post-treatment were collected. Three months later, samples from 633 of these people were re-assessed by both qPCR and KK, re-treated with albendazole and the expelled worms collected. RESULTS: Baseline prevalence by qPCR (n = 796) was 17 % for A. lumbricoides, 18 % for Necator americanus, 41 % for Giardia lamblia and 15% for Entamoeba histolytica. The prevalence was <1% for Trichuris trichiura, Ancylostoma duodenale, Strongyloides stercoralis and Cryptosporidium parvum. The sensitivity of qPCR was 98% for A. lumbricoides and N. americanus, whereas KK sensitivity was 70% and 32%, respectively. Furthermore, qPCR detected infections with T. trichiura and S. stercoralis that were missed by KK, and infections with G. lamblia and E. histolytica that cannot be detected by KK. Infection intensities measured by qPCR and by KK were correlated for A. lumbricoides (r = 0.83, p < 0.0001) and N. americanus (r = 0.55, p < 0.0001). The number of A. lumbricoides worms expelled was correlated (p < 0.0001) with both the KK (r = 0.63) and qPCR intensity measurements (r = 0.60). CONCLUSIONS: KK may be an inadequate tool for stool-based surveillance in areas where hookworm or Strongyloides are common or where intensity of helminth infection is low after repeated rounds of chemotherapy. Because deworming programs need to distinguish between populations where parasitic infection is controlled and those where further treatment is required, multi-parallel qPCR (or similar high throughput molecular diagnostics) may provide new and important diagnostic information
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