520 research outputs found
Prediction of the radial solids concentration distribution in circulating fluidized bed risers
The presented work deals with the development of a model for the prediction of the radial solids concentration distribution in circulating fluidized bed risers. In order to provide a substantial basis for the model development, nonâinvasive investigations on the solids distribution over the cross-section of a pilot plant scale circulating fluidized bed riser are carried out using Xâray computed tomography. The examined operating range covers cross-section averaged solids concentrations between 2.7 vol.% and 38.1 vol.% while superficial gas velocities were adjusted in the range from 0.4 m sâ1 up to 6.0 m sâ1. Especially in the case of dense gasâsolid flow conditions detrimental beam hardening effects gain influence, distorting the results of the X-ray measurements (1). Thus, a novel calibration method is presented to facilitate the derivation of volumetric solids concentrations from the measured tomographic attenuation data. In this, an emphasized feature consists in the elimination of low energetic radiation from the incident Xâray spectrum to avoid beam hardening effects, which are caused by the pipe material and the fluidized solids. Evaluation of the presented technique by comparison of the derived cross-section averaged solids concentrations with those obtained from differential pressure measurements confirms its high accuracy. Subsequently, the technique is applied for quantitative analysis of the radial solids concentration distribution in a gasâsolid circulating fluidized bed riser in dependence of the overall solids holdup and the superficial gas velocity. The high spatial resolution and the non-invasive character of the applied technique allow for detailed examination of the solids concentration prevailing in close proximity of the inner riser wall as well as in the center of the cross-section. The tomographic Xâray scans of the cross-section of the riser, operated under dilute and highly dense conditions, provide a comprehensive set of measurement data, based on which a model is developed that allows for the prediction of the radial solids concentration distribution in vertical gas-solid upflow. The proposed model is found to reliably predict the radial solids concentration distribution under dilute as well as under dense flow conditions.
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CNN based Cuneiform Sign Detection Learned from Annotated 3D Renderings and Mapped Photographs with Illumination Augmentation
Motivated by the challenges of the Digital Ancient Near Eastern Studies
(DANES) community, we develop digital tools for processing cuneiform script
being a 3D script imprinted into clay tablets used for more than three
millennia and at least eight major languages. It consists of thousands of
characters that have changed over time and space. Photographs are the most
common representations usable for machine learning, while ink drawings are
prone to interpretation. Best suited 3D datasets that are becoming available.
We created and used the HeiCuBeDa and MaiCuBeDa datasets, which consist of
around 500 annotated tablets. For our novel OCR-like approach to mixed image
data, we provide an additional mapping tool for transferring annotations
between 3D renderings and photographs. Our sign localization uses a RepPoints
detector to predict the locations of characters as bounding boxes. We use image
data from GigaMesh's MSII (curvature, see https://gigamesh.eu) based rendering,
Phong-shaded 3D models, and photographs as well as illumination augmentation.
The results show that using rendered 3D images for sign detection performs
better than other work on photographs. In addition, our approach gives
reasonably good results for photographs only, while it is best used for mixed
datasets. More importantly, the Phong renderings, and especially the MSII
renderings, improve the results on photographs, which is the largest dataset on
a global scale.Comment: This paper was accepted to ICCV23 and includes the DOI for an Open
Access Dataset with annotated cuneiform scrip
Generating Component Designs for an Improved NVH Performance by Using an Artificial Neural Network as an Optimization Metamodel
In modern vehicle development, suspension components have to meet many boundary conditions. In noise, vibration, and harshness (NVH) development these are for example eigenfrequencies and frequency response function (FRF) amplitudes. Component geometry parameters, for example kinematic hard points, often affect multiple of these targets in a non intuitive way. In this article, we present a practical approach to find optimized parameters for a component design, which fulfills an FRF target curve. By morphing an initial component finite element model we create training data for an artificial neural network (ANN) which predicts FRFs from geometry parameter input. Then the ANN serves as a metamodel for an evolutionary algorithm optimizer which identifies fitting geometry parameter sets, meeting an FRF target curve. The methodology enables a component design which considers an FRF as a component target. In multiple simulation examples we demonstrate the capability of identifying component designs modifying specific eigenfrequency or amplitude features of the FRFs
Broadband Geodesic Pulses for Three Spin Systems: Time-Optimal Realization of Effective Trilinear Coupling Terms and Indirect SWAP Gates
Broadband implementations of time-optimal geodesic pulse elements are
introduced for the efficient creation of effective trilinear coupling terms for
spin systems consisting of three weakly coupled spins 1/2. Based on these pulse
elements, the time-optimal implementation of indirect SWAP operations is
demonstrated experimentally. The duration of indirect SWAP gates based on
broadband geodesic sequence is reduced by 42.3% compared to conventional
approaches.Comment: 22 pages, incl. 8 figure
Hyperendemic dengue transmission and identification of a locally evolved DENV-3 lineage, Papua New Guinea 2007-2010
Background
Dengue is endemic in the Western Pacific and Oceania and the region reports more than 200,000 cases annually. Outbreaks of dengue and severe dengue occur regularly and movement of virus throughout the region has been reported. Disease surveillance systems, however, in many areas are not fully established and dengue incidence is underreported. Dengue epidemiology is likely least understood in Papua New Guinea (PNG), where the prototype DENV-2 strain New Guinea C was first isolated by Sabin in 1944 but where routine surveillance is not undertaken and little incidence and prevalence data is available.
Methodology/Principal findings
Serum samples from individuals with recent acute febrile illness or with non-febrile conditions collected between 2007â2010 were tested for anti-DENV neutralizing antibody. Responses were predominantly multitypic and seroprevalence increased with age, a pattern indicative of endemic dengue. DENV-1, DENV-2 and DENV-3 genomes were detected by RT-PCR within a nine-month period and in several instances, two serotypes were identified in individuals sampled within a period of 10 days. Phylogenetic analysis of whole genome sequences identified a DENV-3 Genotype 1 lineage which had evolved on the northern coast of PNG which was likely exported to the western Pacific five years later, in addition to a DENV-2 Cosmopolitan Genotype lineage which had previously circulated in the region.
Conclusions/Significance
We show that dengue is hyperendemic in PNG and identify an endemic, locally evolved lineage of DENV-3 that was associated with an outbreak of severe dengue in Pacific countries in subsequent years, although severe disease was not identified in PNG. Additional studies need to be undertaken to understand dengue epidemiology and burden of disease in PNG
Medien, Interfaces und implizites Wissen
Die BeitrÀge des Heftes zeigen auf, wie sich das VerhÀltnis von Medien und implizitem Wissen unter den Bedingungen des Internets der Dinge, im Kontext der Robotik oder in Bezug auf ökonomische Fragen ausgestaltet.
Erörtert werden dabei vorrangig Fragestellungen, die an die Interfaces dieser zeitgenössischen Medientechnologien gerichtet werden können. Vor dem Hintergrund medien- und interfacetheoretischer Ăberlegungen wird aufgezeigt, welche medienwissenschaftlichen Konsequenzen sich fĂŒr die Analyse dieser kulturellen PhĂ€nomene und gesellschaftlichen Felder ergeben
How enhancers regulate wavelike gene expression patterns
A key problem in development is to understand how genes turn on or off at the right place and right time during embryogenesis. Such decisions are made by non-coding sequences called âenhancers.â Much of our models of how enhancers work rely on the assumption that genes are activated de novo as stable domains across embryonic tissues. Such a view has been strengthened by the intensive landmark studies of the early patterning of the anterior-posterior (AP) axis of the Drosophila embryo, where indeed gene expression domains seem to arise more or less stably. However, careful analysis of gene expression patterns in other model systems (including the AP patterning in vertebrates and short-germ insects like the beetle Tribolium castaneum) painted a different, very dynamic view of gene regulation, where genes are oftentimes expressed in a wavelike fashion. How such gene expression waves are mediated at the enhancer level is so far unclear. Here, we establish the AP patterning of the short-germ beetle Tribolium as a model system to study dynamic and temporal pattern formation at the enhancer level. To that end, we established an enhancer prediction system in Tribolium based on time- and tissue-specific ATAC-seq and an enhancer live reporter system based on MS2 tagging. Using this experimental framework, we discovered several Tribolium enhancers, and assessed the spatiotemporal activities of some of them in live embryos. We found our data consistent with a model in which the timing of gene expression during embryonic pattern formation is mediated by a balancing act between enhancers that induce rapid changes in gene expression patterns (that we call âdynamic enhancersâ) and enhancers that stabilize gene expression patterns (that we call âstatic enhancersâ). However, more data is needed for a strong support for this or any other alternative models
Isolated hypoxic hepatic perfusion with tumor necrosis factor-alpha, melphalan, and mitomycin C using balloon catheter techniques: a pharmacokinetic study in pigs
OBJECTIVE: To validate the methodology of isolated hypoxic hepatic
perfusion (IHHP) using balloon catheter techniques and to gain insight
into the distribution of tumor necrosis factor-alpha (TNF), melphalan, and
mitomycin C (MMC) through the regional and systemic blood compartments
when applying these techniques. SUMMARY BACKGROUND DATA: There is no
standard treatment for unresectable liver tumors. Clinical results of
isolated limb perfusion with high-dose TNF and melphalan for the treatment
of melanoma and sarcoma have been promising, and attempts have been made
to extrapolate this success to the isolated liver perfusion setting. The
magnitude and toxicity of the surgical procedure, however, have limited
clinical applicability. METHODS: Pigs underwent IHHP with TNF, melphalan,
and MMC using balloon catheters or served as controls, receiving
equivalent dosages of these agents intravenously. After a 20-minute
perfusion, a washout procedure was performed for 10 minutes, after which
isolation was terminated. Throughout the procedure and afterward, blood
samples were obtained from the hepatic and systemic blood compartments and
concentrations of perfused agents were determined. RESULTS: During
perfusion, locoregional plasma drug concentrations were 20- to 40-fold
higher than systemic concentrations. Compared with systemic concentrations
after intravenous administration, regional concentrations during IHHP were
up to 10-fold higher. Regional MMC and melphalan levels steadily declined
during perfusion, indicating rapid uptake by the liver tissue; minimal
systemic concentrations indicated virtually no leakage to the systemic
blood compartment. During isolation, concentrations of TNF in the
perfusate declined only slightly, indicating limited uptake by the liver
tissue; no leakage of TNF to the systemic circulation was observed. After
termination of isolation, systemic TNF levels showed only a minor
transient elevation, indicating that the washout procedure at the end of
the perfusions was fully effective. CONCLUSIONS: Complete isolation of the
hepatic vascular bed can be accomplished when performing IHHP using this
balloon catheter technique. Thus, as in extremities, an ideal leakage-free
perfusion of the liver can now be performed, and repeated, without major
surgery. The effective washout allows the addition of TNF in this setting
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