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排序方式: 共有846条查询结果,搜索用时 15 毫秒
1.
In-situ full-field measurements became one of the drivers for process understanding, model creation, validation and inverse analysis. Therefore, a novel spatio-temporal optical flow method for the robust measurement of higher-order strain derivatives is proposed. This computer vision approach overcomes inherent restrictions of established DIC methods. For advanced process analysis of shear cutting processes, the deformation curvature (2nd-order displacement derivative) and the respective rate (3rd-order displacement derivative) are of high interest. For the first time, it is possible to quantify experimentally these higher-order derivatives in sufficient quality with the proposed spatio-temporal optical flow approach. In addition, interesting correlations between the microstructure of the material and macroscopic process results are determined. This demonstrates the potential of the novel in-situ measurement approach for the advanced process analysis of metal forming processes in general. 相似文献
2.
Sandra Fleischer Stefan C. Weiss Thomas Lucke Wolfram Seitz Wolfgang Schulz Walter H. Weber 《臭氧:科学与工程》2015,37(5):441-449
Although oxamic acid has been identified as an ozone oxidation product from several precursor compounds, concentrations for drinking water have not been published previously. This study shows results from a full-scale drinking water treatment plant, noting that the mean concentrations for oxamic acid reached 21.3 μg/L after ozonation and prior to filtration. Subsequent multiple-layer filtration removed 85% of oxamic acid on average, and mean concentrations in drinking water were 2 μg/L. Up to 5.9% of the oxamic acid found in ozone-treated groundwater may be formed from Chloridazon metabolites. 相似文献
3.
Andreas Winkel Wibke Dempwolf Eva Gellermann Magdalena Sluszniak Sebastian Grade Wieland Heuer Michael Eisenburger Henning Menzel Meike Stiesch 《International journal of molecular sciences》2015,16(2):4327-4342
Peri-implant infections from bacterial biofilms on artificial surfaces are a common threat to all medical implants. They are a handicap for the patient and can lead to implant failure or even life-threatening complications. New implant surfaces have to be developed to reduce biofilm formation and to improve the long-term prognosis of medical implants. The aim of this study was (1) to develop a new method to test the antibacterial efficacy of implant surfaces by direct surface contact and (2) to elucidate whether an innovative antimicrobial copolymer coating of 4-vinyl-N-hexylpyridinium bromide and dimethyl(2-methacryloyloxyethyl) phosphonate (VP:DMMEP 30:70) on titanium is able to reduce the attachment of bacteria prevalent in peri-implant infections. With a new in vitro model with semi-coated titanium discs, we were able to show a dramatic reduction in the adhesion of various pathogenic bacteria (Streptococcus sanguinis, Escherichia coli, Staphylococcus aureus, Staphylococcus epidermidis), completely independently of effects caused by soluble materials. In contrast, soft tissue cells (human gingival or dermis fibroblasts) were less affected by the same coating, despite a moderate reduction in initial adhesion of gingival fibroblasts. These data confirm the hypothesis that VP:DMMEP 30:70 is a promising antibacterial copolymer that may be of use in several clinical applications. 相似文献
4.
Avalanche‐Discharge‐Induced Electrical Forming in Tantalum Oxide‐Based Metal–Insulator–Metal Structures 下载免费PDF全文
Katharina Skaja Christoph Bäumer Oliver Peters Stephan Menzel Marco Moors Hongchu Du Manuel Bornhöfft Christoph Schmitz Vitaliy Feyer Chun‐Lin Jia Claus Michael Schneider Joachim Mayer Rainer Waser Regina Dittmann 《Advanced functional materials》2015,25(46):7154-7162
Oxide‐based metal–insulator–metal structures are of special interest for future resistive random‐access memories. In such cells, redox processes on the nanoscale occur during resistive switching, which are initiated by the reversible movement of native donors, such as oxygen vacancies. The formation of these filaments is mainly attributed to an enhanced oxygen diffusion due to Joule heating in an electric field or due to electrical breakdown. Here, the development of a dendrite‐like structure, which is induced by an avalanche discharge between the top electrode and the Ta2O5‐x layer, is presented, which occurs instead of a local breakdown between top and bottom electrode. The dendrite‐like structure evolves primarily at structures with a pronounced interface adsorbate layer. Furthermore, local conductive atomic force microscopy reveals that the entire dendrite region becomes conductive. Via spectromicroscopy it is demonstrated that the subsequent switching is caused by a valence change between Ta4+ and Ta5+, which takes place over the entire former Pt/Ta2O5‐x interface of the dendrite‐like structure. 相似文献
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6.
Landsiedel Justus Root Waleri Schramm Christian Menzel Alexander Witzleben Steffen Bechtold Thomas Pham Tung 《Nano Research》2020,13(10):2658-2664
Nano Research - Development of colored surfaces by formation of nano-structured aggregates is a widely used strategy in nature to color lightweight structures (e.g. butterflies) without the use of... 相似文献
7.
Redistribution of internal forces in the lateral bracing system / Schnittgrößenumlagerungen bei der Gebäudeaussteifung 下载免费PDF全文
Kenan Michel MSc. Prof. Dr.‐Ing. Wolfram Jäger Dr.‐Ing. Frank Steinigen 《Mauerwerk》2015,19(6):441-452
The lateral bracing system of a building should ensure the stability of the building, in terms of the usability and the total load capacity. The governing loads for the lateral bracing system are horizontal loads due to wind and earthquake. The horizontal loads are traditionally distributed to the bracing elements according to the uncracked elastic state dependent on the bending stiffness in the elastic (uncracked) state. This method does not allow consideration of non‐linear effects and load redistribution. Within the framework of the PRB Research Cooperation – Improving the Practical Use of Structural Design Standards through pre‐normative work – Subcontract 5: Masonry Construction, Subproject 3: “Large Shear Walls” [7], the cracked or plastic state can be taken into account through a displacement based approach. A matrix formulation for both the linear and cracked states has been derived and implemented. 相似文献
8.
Computational Economics - We study the functioning of informal value transfer systems through the example of Hawala. By complementing the institutional theory with computational experiments that... 相似文献
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10.
Fabien Paulot David Paynter Vaishali Naik Sergey Malyshev Raymond Menzel Larry W. Horowitz 《International Journal of Hydrogen Energy》2021,46(24):13446-13460
Hydrogen (H2) has been proposed as an alternative energy carrier to reduce the carbon footprint and associated radiative forcing of the current energy system. Here, we describe the representation of H2 in the GFDL-AM4.1 model including updated emission inventories and improved representation of H2 soil removal, the dominant sink of H2. The model best captures the overall distribution of surface H2, including regional contrasts between climate zones, when vd(H2) is modulated by soil moisture, temperature, and soil carbon content. We estimate that the soil removal of H2 increases with warming (2–4% per K), with large uncertainties stemming from different regional response of soil moisture and soil carbon. We estimate that H2 causes an indirect radiative forcing of 0.84 mW m?2/(Tg(H2)yr?1) or 0.13 mW m?2 ppbv?1, primarily due to increasing CH4 lifetime and stratospheric water vapor production. 相似文献