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排序方式: 共有871条查询结果,搜索用时 15 毫秒
61.
The oxidation of AISI 316L(NG) stainless steel in simulated pressurised water reactor (PWR) coolant with or without addition of 1 ppm Zn at 280 °C for up to 96 h has been characterised in situ by electrochemical impedance spectroscopy (EIS), both at the corrosion potential and under anodic polarisation up to 0.5 V vs. the reversible hydrogen electrode (RHE). Additional tests were performed in simulated PWR coolant with the addition of 0.01 M Na2B4O7 to exclude the effect of pH excursions probably due to Zn hydrolysis reactions. The thickness and in-depth composition of the oxide films formed at open circuit and at 0.5 V vs. RHE in the investigated electrolytes have been estimated from X-ray photoelectron spectroscopy (XPS) depth profiles. The kinetic and transport parameters characterising the oxide layer growth have been estimated using a calculational procedure based on the mixed conduction model for oxide films. Successful simulations of both the EIS and XPS data have been obtained. The parameter estimates are discussed in terms of the effect of Zn on the oxide layers on stainless steel in PWR conditions. 相似文献
62.
63.
Timo Koch Karl-Heinz Heinig Michael Jentschel Hans G. B?rner 《Journal of research of the National Institute of Standards and Technology》2000,105(1):81-87
Crystal-GRID measurements have been performed with ZnS single crystals. For the first time, an asymmetric Crystal-GRID line shape could be observed. The preliminary data evaluation indicates that the reported lifetime of the 3221 keV level in 33S is too short. A value of about 60 fs has been found. Due to this “long” lifetime the line shape is much less structured than calculated with the reported lifetime. 相似文献
64.
Reconfiguring flexible machine modules of a PCB assembly line 总被引:2,自引:0,他引:2
Assembly of electronic components to Printed Circuit Boards (PCB) is a complicated manufacturing process and therefore its
control is usually divided into several subtasks which are handled separately. We consider the combined task of determining
a machine configuration and line balancing for a single assembly line of interconnected, reconfigurable machine modules and
one PCB type in production. The modules can be tailored to the needs of each PCB type by suitable assignments for placement
heads, nozzles and feeders. Out of these, the component-to-machine assignment appears to be most difficult and we propose
five different solution methods for it; brute force, random, greedy, local search and genetic algorithm. The genetic algorithm
outperformed the other methods in practical test. 相似文献
65.
Timo Kurz Alex Hakenjos Jrme Krmer Mario Zedda Carsten Agert 《Journal of power sources》2008,180(2):742-747
This work presents a control strategy for PEM fuel cell systems based on simultaneous impedance measurements on single cells. This control strategy distinguishes between flooding and drying of the cells in a stack and helps to run the stack at an optimal operating point. In the presented experiments, it has been found that impedance measurements can detect flooding phenomena in single cells minutes before they can be seen in related polarisation curves. It is shown that impedance measurements at two specific frequencies, one high and one low frequency impedance, are sufficient to predict voltage drops caused by flooding and drying. In flooding mode, the imaginary part of the low frequency impedance changes while the high frequency impedance remains stable and vice versa in drying mode. This technique reduces measuring time compared to the measurement of whole impedance spectra, without losing important information for the control of the system. 相似文献
66.
The ability of an agglomerated cellulose powder to total and plastic deformation was evaluated and compared with those of Avicel PH 101, Emcocel and an experimental depolymerized cellulose powder. The elastic recovery of compressed cellulose tablets was also measured. The effects of deformation of the material during the tableting process and recovery of tablet after maximum compression on the mechanical strength of tablets were also discussed.
The apparent net work done into tablets during compression as well as the yield pressures to total and plastic deformation, determined from the Heckel treatment, showed no great differences between the agglomerated cellulose powder and the other cellulose powders. Thus all the cellulose materials studied had rather similar ability to total, i.e. elastic and plastic, deformation and to permanent, i.e. pure plastic, deformation. The obvious fragmentation of the agglomerated cellulose powder already at low compressional pressure, however, seemed to be advantageous for the formation of strong compacts.
Both rapid and total elastic recovery of compressed cellulose tablets showed clear differences between the cellulose materials and these differences correlated with the previously measured strength of cellulose tablets. The agglomerated cellulose powder had the smallest tendency to both kind of elastic recoveries of tablets. Obviously, due to the large interparticle contact areas, the ability of this material to establish more bonds between adjacent particles during compression was greater than those of other celluloses. The elastic recovery was greatest for depolymerized cellulose tablets indicating the poorest binding ability of the particles of this material. 相似文献
The apparent net work done into tablets during compression as well as the yield pressures to total and plastic deformation, determined from the Heckel treatment, showed no great differences between the agglomerated cellulose powder and the other cellulose powders. Thus all the cellulose materials studied had rather similar ability to total, i.e. elastic and plastic, deformation and to permanent, i.e. pure plastic, deformation. The obvious fragmentation of the agglomerated cellulose powder already at low compressional pressure, however, seemed to be advantageous for the formation of strong compacts.
Both rapid and total elastic recovery of compressed cellulose tablets showed clear differences between the cellulose materials and these differences correlated with the previously measured strength of cellulose tablets. The agglomerated cellulose powder had the smallest tendency to both kind of elastic recoveries of tablets. Obviously, due to the large interparticle contact areas, the ability of this material to establish more bonds between adjacent particles during compression was greater than those of other celluloses. The elastic recovery was greatest for depolymerized cellulose tablets indicating the poorest binding ability of the particles of this material. 相似文献
67.
We describe how the cash-point service problem of Formal Methods ’99 is specified using DisCo [Dis, JKS91].
Received January 2000 / Accepted in revised form December 2000 相似文献
68.
One Question,Multiple Answers: Biochemical and Biophysical Screening Methods Retrieve Deviating Fragment Hit Lists 下载免费PDF全文
Dr. Johannes Schiebel Nedyalka Radeva Dr. Helene Köster Dr. Alexander Metz Timo Krotzky Dr. Maren Kuhnert Prof. Wibke E. Diederich Prof. Andreas Heine Dr. Lars Neumann Dr. Cedric Atmanene Dominique Roecklin Dr. Valérie Vivat‐Hannah Dr. Jean‐Paul Renaud Dr. Robert Meinecke Dr. Nina Schlinck Dr. Astrid Sitte Franziska Popp Dr. Markus Zeeb Prof. Gerhard Klebe 《ChemMedChem》2015,10(9):1511-1521
Fragment‐based lead discovery is gaining momentum in drug development. Typically, a hierarchical cascade of several screening techniques is consulted to identify fragment hits which are then analyzed by crystallography. Because crystal structures with bound fragments are essential for the subsequent hit‐to‐lead‐to‐drug optimization, the screening process should distinguish reliably between binders and non‐binders. We therefore investigated whether different screening methods would reveal similar collections of putative binders. First we used a biochemical assay to identify fragments that bind to endothiapepsin, a surrogate for disease‐relevant aspartic proteases. In a comprehensive screening approach, we then evaluated our 361‐entry library by using a reporter‐displacement assay, saturation‐transfer difference NMR, native mass spectrometry, thermophoresis, and a thermal shift assay. While the combined results of these screening methods retrieve 10 of the 11 crystal structures originally predicted by the biochemical assay, the mutual overlap of individual hit lists is surprisingly low, highlighting that each technique operates on different biophysical principles and conditions. 相似文献
69.
Mari Kallioinen Mika Mänttäri Jutta Nuortila-Jokinen Timo Sutela 《Desalination》2010,250(3):1002-1004
The total effluent load of a paper mill can be significantly decreased by recycling of purified clear filtrate (CF) back to paper-making process. The CF treated with membranes can be reused, for instance, as wire section shower water and in the dilution of chemicals. The main requirements for a membrane in CF treatment are high filtration capacity, high retention of turbidity and low fouling tendency. Previous studies have shown that the regenerated cellulose (RC) ultrafiltration (UF) membrane C30F (current trade name UC030T) is especially suitable for the treatment of paper mill process waters. Every paper-making process is, however, different. Thus, filtration experiments are required in order to find the most optimal membrane for the treatment of a certain process water. In this study the best membrane for the treatment of acidic clear filtrate (ACF) was searched. The performance of the C30F membrane was compared with five UF and three microfiltration (MF) membranes. The results revealed that in addition to the C30F membrane, also some other membranes produced high filtration capacity with ACF (approximately 200 L/(m2h bar)). All the tested membranes also retained over 90% of turbidity. The extremely hydrophilic C30F membrane had, however, lower fouling tendency compared to the other tested membranes. Therefore, it was concluded that the C30F membranes were the best possible membrane for the ACF treatment. 相似文献
70.
Vamsi Krishna Palukuru Jani Peräntie Mikko Komulainen Timo Tick Heli Jantunen 《Journal of the European Ceramic Society》2010,30(2):389-394
A tunable microwave phase shifter composed of a low-sintering-temperature, screen-printable barium strontium titanate (BST) film and silver metallization was fabricated on an alumina substrate and co-fired at 900 °C for 3 h. The dielectric properties of the films were characterized in a frequency range of 0.8–8 GHz using scattering parameter measurements and a quasi-static coplanar waveguide transmission line model. The temperature dependency of the films was measured through capacitance measurements in a frequency range of 0.5–2.5 GHz. The figure of merit (phase shift/dB of insertion loss) of the phase shifter was found to be 14.6 at 3 GHz with an applied bias field strength of 2.5 V/μm. The performance of the phase shifter is briefly discussed and compared with other phase shifters fabricated by direct screen-printing of BST films. 相似文献