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61.
Quirin Meyer Jochen Süßmuth Gerd Sußner Marc Stamminger Günther Greiner 《Computer Graphics Forum》2010,29(4):1405-1409
In this paper we analyze normal vector representations. We derive the error of the most widely used representation, namely 3D floating‐point normal vectors. Based on this analysis, we show that, in theory, the discretization error inherent to single precision floating‐point normals can be achieved by 250.2 uniformly distributed normals, addressable by 51 bits. We review common sphere parameterizations and show that octahedron normal vectors perform best: they are fast and stable to compute, have a controllable error, and require only 1 bit more than the theoretical optimal discretization with the same error. 相似文献
62.
Hans-Juergen Odenthal Uwe Thiedemann Udo Falkenreck Jochen Schlueter 《Metallurgical and Materials Transactions B》2010,41(2):396-413
The oscillation of argon oxygen decarburization (AOD) converters is flow related and depends on the process parameters (e.g., vessel geometry, melt fill height, process gas type and blowing rate, vessel tilting angle, as well as geometry, number,
and arrangement of the side-wall nozzles). For a 120-ton AOD converter with seven submerged side-wall nozzles, plant tests,
physical simulations on a 1:4 scale water model, and computational fluid dynamics simulations have been done. The investigations
show that the penetration depth of an inert gas jet into the melt does not exceed approximately 0.4 m. The plumes are located
close to the nozzle-side converter wall and induce a large-scale primary vortex as well as intensive surface movements; both
are responsible for the oscillation. Several process mechanisms were investigated. The oscillation is highest in the last
stage of the dynamic blow and is still high during the reduction stage. As the amount of inert gas increases, the vibration
level also increases. Inert gas has a greater influence on the oscillation than oxygen. Tilting the converter around 8 deg
clearly leads to more intensive oscillations. Increasing the blowing rate increases the forces and torques acting on the vessel,
whereas the oscillation frequency remains nearly constant. A varying fill level does not influence the vibration level the
same way as the blowing rate. The operational test shows, for example, that the maximum torque does not depend on the heat
size when the latter varies between –8 pct and +21 pct of the nominal heat size. The water model test shows decreasing forces
and torques with a rising fill level. 相似文献
63.
Andreas Opitz Bernhard Ecker Julia Wagner Alexander Hinderhofer Frank Schreiber Jochen Manara Jens Pflaum Wolfgang Brütting 《Organic Electronics》2009,10(7):1259-1267
Blends of organic electron and hole conductive materials are widely used for ambipolar charge carrier transport and photovoltaic cells. An obvious choice for donor–acceptor blends are organic semiconducting materials in their hydrogenated and fluorinated form, since they combine potentially suitable electronic properties with structural compatibility of the two constituents. This study focuses on the structural, optical, and electrical properties of blends using hydrogenated copper-phthalocyanine (H16CuPc) in combination with its per-fluorinated version (F16CuPc). Using X-ray scattering, scanning force microscopy and optical absorption measurements we show that mixed crystalline films are obtained by co-evaporation of the two materials. Electrical transport measurements reveal a profound reduction of the current for bipolar charge injection in mixed films. We discuss the formation of self-trapped charge transfer excitons as possible explanation for this unexpected behaviour, which impedes the usability of this system in photovoltaic cells. 相似文献
64.
Ristenbatt M.P. Holland-Mortiz E. Metzger K. 《Industry Applications, IEEE Transactions on》1988,24(2):204-211
A post-disaster signalling system from mine to surface, using through-the-earth electromagnetic propagation of a 1950 Hz carrier, phase modulated by a repeating 255 bit maximal length sequence, is discussed. Coherent integration up to 4.46 min allows output pulse detection on a CRT at input signal-to-noise ratios down up -30 dB, which is about 30 dB less than required for the present pulse transmitter system. The system offers vastly increased reliability along with some combination of increased range, signal processing delay time, smaller transmitter antenna, and reduced power. It avoids a manual signal search period and permits more accurate automated or manual null-seeking emitter location. After location, it can be used with pulse position modulation (PPM) for communication. It should also be valuable for measurements to determine geological properties 相似文献
65.
Small W. IV Metzger M.F. Wilson T.S. Maitland D.J. 《IEEE journal of selected topics in quantum electronics》2005,11(4):892-901
Due to the narrow (3-h) treatment window for effective use of the thrombolytic drug recombinant tissue-type plasminogen activator (rt-PA), there is a need to develop alternative treatments for ischemic stroke. We are developing an intravascular device for mechanical thrombus removal using shape memory polymer (SMP). We propose to deliver the SMP microactuator in its secondary straight rod form (length=4 cm, diameter=350 /spl mu/m) through a catheter distal to the vascular occlusion. The microactuator, which is mounted on the end of an optical fiber, is then transformed into its primary corkscrew shape by laser heating (diode laser, /spl lambda/=800 nm) above its soft-phase glass transition temperature (T/sub gs/=55/spl deg/C). Once deployed, the microactuator is retracted, and the captured thrombus is removed to restore blood flow. The SMP is doped with indocyanine green (ICG) dye to increase absorption of the laser light. Successful deployment of the microactuator depends on the optical properties of the ICG-doped SMP, as well as the optical coupling efficiency of the interface between the optical fiber and the SMP. Spectrophotometry, thermal imaging, and computer simulation aided the initial design effort and continue to be useful tools for optimization of the dye concentration and laser power. Thermomechanical testing was performed to characterize the elastic modulus of the SMP. We have demonstrated laser activation of the SMP microactuator in air at room temperature, suggesting this concept is a promising therapeutic alternative to rt-PA. 相似文献
66.
Jochen Alber Hongbing Fan Henning Fernau Rolf Niedermeier Fran Rosamond 《Journal of Computer and System Sciences》2005,71(4):385-405
We establish a refined search tree technique for the parameterized DOMINATING SET problem on planar graphs. Here, we are given an undirected graph and we ask for a set of at most k vertices such that every other vertex has at least one neighbor in this set. We describe algorithms with running times O(8kn) and O(8kk+n3), where n is the number of vertices in the graph, based on bounded search trees. We describe a set of polynomial time data-reduction rules for a more general “annotated” problem on black/white graphs that asks for a set of k vertices (black or white) that dominate all the black vertices. An intricate argument based on the Euler formula then establishes an efficient branching strategy for reduced inputs to this problem. In addition, we give a family examples showing that the bound of the branching theorem is optimal with respect to our reduction rules. Our final search tree algorithm is easy to implement; its analysis, however, is involved. 相似文献
67.
Jochen Homann 《工业材料与腐蚀》1986,37(10):532-543
Fluoroplastics in chemical process engineering, especially as lining/coating materials Fluroplastich such as PTFE (Hostaflon®, Teflon®, etz.), PFA/TFA, FEP, PVDF, ECTFE, ETFE, PCTFE are largely known on the market and accepted in all industries for their excellent properties. Whereas in machine design and the automotive industry their low friction value and in the electrical industry their good dielectric values are essentially decisive, their universal chemical and high thermal resistance, their outstanding anti-adhesivity and phosiological inertness ensured their acceptance in the chemical and generically related industries. All of them are processed thermoplastically with only the PTFE having an exceptional position as it can only be processed by the sintering method and requires special techniques also for subsequent operations (e.g. shaping and welding). Their characteristics represent the basis for a lot of applications in the chemical and electroplating industry, the pharmaceutical and food industry, the laboratory and semi-conductor field as well as in environmental protection where fluoroplastics are used as finished parts such as seals, bearings, diaphragms, compensators, injection-moulded items, heating panels, heat exchangers, etc. Besides fluoroplastics semi-finished parts offer outstanding chances in chemical process engineering. For example steel tanks and sections as well as pipelines get corrosion-proof liners or evelopes against liquid or gaseous media. While the so-called heavy corrosion prevention is usually ensured with thicker material (3 to 4 mm), fluoroplastic coatings possibly offer a limited protection against chemicals only as their maximum coat thickness is approx. 1 mm. Therefore fluoroplastic coatings are mostly applied where it is a question of providing light corrosion prevention or anti-adhesivity and with parts of complex design which can neither be lined nor enveloped as e.g. agitors, spherical inserts, perforated plates, etc. 相似文献
68.
Higher levels of thymidylate synthase gene expression are observed in pulmonary as compared with hepatic metastases of colorectal adenocarcinoma 总被引:1,自引:0,他引:1
69.
JF Tisdale Y Hanazono SE Sellers BA Agricola ME Metzger RE Donahue CE Dunbar 《Canadian Metallurgical Quarterly》1998,92(4):1131-1141
The possibility of primitive hematopoietic cell ex vivo expansion is of interest for both gene therapy and transplantation applications. The engraftment of autologous rhesus peripheral blood (PB) progenitors expanded 10 to 14 days were tracked in vivo using genetic marking. Stem cell factor (SCF)/granulocyte colony-stimulating factor (G-CSF)-mobilized and CD34-enriched PB cells were divided into two equal aliquots and transduced with one of two retroviral vectors carrying the neomycin-resistance gene (neo) for 4 days in the presence of interleukin-3 (IL-3), IL-6, and SCF in the first 5 animals, IL-3/IL-6/SCF/Flt-3 ligand (FLT) in 2 subsequent animals, or IL-3/IL-6/SCF/FLT plus an autologous stromal monolayer (STR) in the final 2. At the end of transduction period, one aliquot (nonexpanded) from each animal was frozen, whereas the other was expanded under the same conditions but without vector for a total of 14 days before freezing. After total body irradiation, both the nonexpanded and expanded transduced cells were reinfused. Despite 5- to 13-fold higher cell and colony-forming unit (CFU) doses from the expanded fraction of marked cells, there was greater short- and long-term marking from the nonexpanded cells in all animals. In animals receiving cells transduced and expanded in the presence of IL-3/IL-6/SCF/FLT, engraftment by the marked expanded cells was further diminished. This discrepancy was even more pronounced in the animals who received cells transduced and expanded in the presence of FLT and autologous stroma, with no marking detectable from the expanded cells. Despite lack of evidence for expansion of engrafting cells, we found that the addition of FLT and especially STR during the initial brief transduction period increased engraftment with marked cells into a clinically relevant range. Levels of marked progeny cells originating from the nonexpanded aliqouts were significantly higher than that seen in previous 4 animals receiving cells transduced in the presence of IL-3/IL-6/SCF, with levels of 10% to 20% confirmed by Southern blotting from the nonexpanded IL-3/IL-6/SCF/FLT/STR graft compared with 0.01% in the original IL-3/IL-6/SCF cohort. These results suggest that, although expansion of PB progenitors is feasible ex vivo, their contribution towards both short- and long-term engraftment is markedly impaired. However, a brief transduction in the presence of specific cytokines and stromal support allows engraftment with an encouraging number of retrovirally modified cells. 相似文献
70.
Stand der Erkenntnisse und Ziel der eigenen Versuche. Anlagenbeschreibung und Betriebsbeobachtungen. Untersuchung der Schlackenbildung während der Schrottvorwärmung. Änderungen der Roheisenzusammensetzung durch Reaktionen mit den Vorwärmschlacken. Betrachtungen zur Sauerstoffbilanz. 相似文献