299 research outputs found
Investigation of parameter uncertainty and identifiability of the hydrological model WaSiM-ETH
International audienceThe identification of optimum model parameters may be influenced by temporal or event-specific changes of optimum parameter ranges and the length and information content of calibration data. These effects were studied for the hydrological model WaSiM-ETH in a 170 km2 catchment. Based on a Monte-Carlo simulation including seven model parameters, we investigated temporal and state dependent changes of parameter identifiability using the DYNIA algorithm. The effect of data length was studied using a modified DYNIA approach based on a growing window algorithm. The DYNIA analysis revealed temporal changes of identifiability for the snow melt runoff parameter cmelt, which is only identifiable during winter runoff, and for the drainage density parameter drd. The drd parameter was closely related to observed discharge (or catchment moisture), when re-ordering the time series by discharge. Such dependencies probably result from processes not included in model equations. The growing window analysis shows that more than one year of data did not result in improved identification of model parameters cmelt and drd. Using the re-ordered data series, good identifiability of cmelt was bound to high discharges, while identifiability of drd changed with the addition of further values in descending or ascending order. The methodology revealed structural problems with regard to the parameter drd, which are not yet completely understood and require further investigation
Comprehensive T-Matrix Reference Database: A 2007-2009 Update
The T-matrix method is among the most versatile, efficient, and widely used theoretical techniques for the numerically exact computation of electromagnetic scattering by homogeneous and composite particles, clusters of particles, discrete random media, and particles in the vicinity of an interface separating two half-spaces with different refractive indices. This paper presents an update to the comprehensive database of T-matrix publications compiled by us previously and includes the publications that appeared since 2007. It also lists several earlier publications not included in the original database
An Evaluation of the Fe-N Phase Diagram Considering Long-Range Order of N Atoms in γ'-Fe4N1-x and ε-Fe2N1-z
The chemical potential of nitrogen was described as a function of nitrogen content for the Fe-N phases α-Fe[N], γ'-Fe4N1-x, and ε-Fe2N1-z. For α-Fe[N], an ideal, random distribution of the nitrogen atoms over the octahedral interstices of the bcc iron lattice was assumed; for γ'-Fe4N1-x and ε-Fe2N1-z, the occurrence of a long-range ordered distribution of the nitrogen atoms over the octahedral interstices of the close packed iron sublattices (fcc and hcp, respectively) was taken into account. The theoretical expressions were fitted to nitrogen-absorption isotherm data for the three Fe-N phases. The α/α + γ', α + γ'/γ', γ'/γ' + ε, and γ' + ε/ε phase boundaries in the Fe-N phase diagram were calculated from combining the quantitative descriptions for the absorption isotherms with the known composition of NH3/H2 gas mixtures in equilibrium with coexisting α and γ' phases and in equilibrium with coexisting γ' and ε phases. Comparison of the present phase boundaries with experimental data and previously calculated phase boundaries showed a major improvement as compared to the previously calculated Fe-N phase diagrams, where long-range order for the nitrogen atoms in the γ' and ε phases was not accounted for
Temperature dependent CO2 behavior in microporous 1-D channels of a metal-organic framework with multiple interaction sites
The MOF with the encapsulated CO2 molecule shows that the CO2 molecule is ligated to the unsaturated Cu(II) sites in the cage using its Lewis basic oxygen atom via an angular eta(1)-(O-A) coordination mode and also interacts with Lewis basic nitrogen atoms of the tetrazole ligands using its Lewis acidic carbon atom. Temperature dependent structure analyses indicate the simultaneous weakening of both interactions as temperature increases. Infrared spectroscopy of the MOF confirmed that the CO2 interaction with the framework is temperature dependent. The strength of the interaction is correlated to the separation of the two bending peaks of the bound CO2 rather than the frequency shift of the asymmetric stretching peak from that of free CO2. The encapsulated CO2 in the cage is weakly interacting with the framework at around ambient temperatures and can have proper orientation for wiggling out of the cage through the narrow portals so that the reversible uptake can take place. On the other hand, the CO2 in the cage is restrained at a specific orientation at 195 K since it interacts with the framework strong enough using the multiple interaction sites so that adsorption process is slightly restricted and desorption process is almost clogged.ope
Status and Prospects of ZnO-Based Resistive Switching Memory Devices
In the advancement of the semiconductor device technology, ZnO could be a prospective alternative than the other metal oxides for its versatility and huge applications in different aspects. In this review, a thorough overview on ZnO for the application of resistive switching memory (RRAM) devices has been conducted. Various efforts that have been made to investigate and modulate the switching characteristics of ZnO-based switching memory devices are discussed. The use of ZnO layer in different structure, the different types of filament formation, and the different types of switching including complementary switching are reported. By considering the huge interest of transparent devices, this review gives the concrete overview of the present status and prospects of transparent RRAM devices based on ZnO. ZnO-based RRAM can be used for flexible memory devices, which is also covered here. Another challenge in ZnO-based RRAM is that the realization of ultra-thin and low power devices. Nevertheless, ZnO not only offers decent memory properties but also has a unique potential to be used as multifunctional nonvolatile memory devices. The impact of electrode materials, metal doping, stack structures, transparency, and flexibility on resistive switching properties and switching parameters of ZnO-based resistive switching memory devices are briefly compared. This review also covers the different nanostructured-based emerging resistive switching memory devices for low power scalable devices. It may give a valuable insight on developing ZnO-based RRAM and also should encourage researchers to overcome the challenges
Die Verbindung von Augustinismus und Mystik im späten Mittelalter und in der frühen reformatorischen Bewegung
Efficacy and safety of vertebroplasty for treatment of painful osteoporotic vertebral fractures: a randomised controlled trial [ACTRN012605000079640]
Background. Vertebroplasty is a promising but as yet unproven treatment for painful osteoporotic vertebral fractures. It involves radiographic-guided injection of various types of bone cement directly into the vertebral fracture site. Uncontrolled studies and two controlled quasi-experimental before-after studies comparing volunteers who were offered treatment to those who refused it, have suggested an early benefit including rapid pain relief and improved function. Conversely, several uncontrolled studies and one of the controlled before-after studies have also suggested that vertebroplasty may increase the risk of subsequent vertebral fractures, particularly in vertebrae adjacent to treated levels or if cement leakage into the adjacent disc has occurred. As yet, there are no completed randomised controlled trials of vertebroplasty for osteoporotic vertebral fractures. The aims of this participant and outcome assessor-blinded randomised placebo-controlled trial are to i) determine the short-term efficacy and safety (3 months) of vertebroplasty for alleviating pain and improving function for painful osteoporotic vertebral fractures; and ii) determine its medium to longer-term efficacy and safety, particularly the risk of further fracture over 2 years. Design. A double-blind randomised controlled trial of 200 participants with one or two recent painful osteoporotic vertebral fractures. Participants will be stratified by duration of symptoms (< and ≥ 6 weeks), gender and treating radiologist and randomly allocated to either the treatment or placebo. Outcomes will be assessed at baseline, 1 week, 1, 3, 6, 12 and 24 months. Outcome measures include overall, night and rest pain on 10 cm visual analogue scales, quality of life measured by the Assessment of Quality of Life, Osteoporosis Quality of Life and EQ-5D questionnaires; participant perceived recovery on a 7-point ordinal scale ranging from 'a great deal worse' to 'a great deal better'; disability measured by the Roland-Morris Disability Questionnaire; timed 'Up and Go' test; and adverse effects. The presence of new fractures will be assessed by radiographs of the thoracic and lumbar spine performed at 12 and 24 months. Discussion. The results of this trial will be of major international importance and findings will be immediately translatable into clinical practice. Trial registration. Australian Clinical Trial Register # [ACTRN012605000079640]. © 2008 Buchbinder et al; licensee BioMed Central Ltd.Rachelle Buchbinder, Richard H Osborne, Peter R Ebeling, John D Wark, Peter Mitchell, Chris J Wriedt, Lainie Wengier, David Connell, Stephen E Graves, Margaret P Staples and Bridie Murph
Adaptation of land management in the Mediterranean under scenarios of irrigation water use and availability
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