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排序方式: 共有2137条查询结果,搜索用时 15 毫秒
101.
Linards Lap
inskis Kaspars Mlnieks Juris Blms Mris Knite Sven Oras Tanel Kmbre Sergei Vlassov Mikk Antsov Martin Timusk Andris utka 《大分子材料与工程》2020,305(1)
In the present work, the contact electrification of polymers that differ in adhesion strength is studied. Electrical current is measured along with adhesion in macroscale contacting‐separation experiments. Additionally, local adhesion and roughness are studied with atomic force microscopy to get deeper insight into relations between surface properties and electrification. Measurements reveal that higher surface charge is formed on more adhesive surfaces, thus confirming covalent bond cleavage as a mechanism for contact electrification of polymers. Investigated materials possess enhanced contact electrification making them attractive candidates for the conversion of mechanical energy to electrical in triboelectric nanogenerator devices. 相似文献
102.
Diederik Verkest Julio Leao Da Silva Jr. Chantal Ykman Kris Croes Miguel Miranda Sven Wuytack Francky Catthoor Gjalt De Jong Hugo De Man 《The Journal of VLSI Signal Processing》1999,21(3):185-194
MATISSE is a design environment intended for developing systems characterized by a tight interaction between control and data-flow behavior, intensive data storage and transfer, and stringent real-time requirements. Matisse bridges the gap from a system specification, using a concurrent object-oriented language, to an optimized embedded single-chip hardware/software implementation. Matisse supports stepwise exploration and refinement of dynamic memory management, memory architecture exploration, and gradual incorporation of timing constraints before going to traditional tools for hardware synthesis, software compilation, and inter-processor communication synthesis. With this approach, specifications of embedded systems can be written in a high-level programming language using data abstraction. Application of MATISSE on telecom protocol processing systems in the ATM area shows significant improvements in area usage and power consumption. 相似文献
103.
104.
L. Ingemarsson K. Hellström L.G. Johansson J.E. Svensson M. Halvarsson 《Intermetallics》2011,19(9):1319-1329
The oxidation of a Mo(Si,Al)2 composite is investigated at 1500 °C in dry air using exposure times from 1 to 1000 h. Cross sections are examined with Scanning Electron Microscopy (SEM) and the phase composition is analyzed by X-ray diffraction (XRD). The material forms a continuous and protective alumina layer, the growth of the alumina layer following parabolic kinetics. Immediately below the scale Mo(Si,Al)2 is replaced by a Mo5(Si,Al)3 layer due to the flux of aluminum to the scale. The Al concentration in the Mo(Si,Al)2 phase in the underlying substrate decreases from 27% before exposure to 16–17% after 1000 h. The continuous alumina layer becomes covered by a top layer consisting of alumina grains embedded in a viscous melt with approximate composition 7 Na2O–15 Al2O3–78 SiO2. With time, sodium is volatilized from the melt and the top scale layer transforms to a mixture of alumina, mullite and silica melt. 相似文献
105.
Sven Hermansson Fredrik Lind Henrik Thunman 《Chemical Engineering Research and Design》2011,89(11):2470-2476
Combustion of biomass for heat and power production is continuously growing in importance, because of incentives for replacing fossil energy resources with renewable ones. In biomass combustion, the moisture content of the fuel is an essential operation parameter, which often fluctuates for biomass fuels. Variation in moisture content complicates the operation of the furnaces and results in an uncertainty in the energy content of the fuel delivered to a plant. The fuel moisture-content in a furnace may be determined either by direct measurement on the entering fuel or by measuring the moisture and oxygen contents of the flue gases deriving the moisture content of the fuel. However, reliable methods of a motivated cost for the small to medium-scale furnaces are today not available. An exception is if the furnace is equipped with flue-gas condenser, which can be used to estimate the moisture content of the flue gases. A limitation of this method is, though, that not all furnaces have flue-gas condensers and that the measured signal has an inherent time delay.In this work, measurement of the relative humidity (RH) of the flue gases from a furnace is investigated as the central component in the on-line monitoring of the moisture content of the fuel in a furnace. The method was analysed with humid air in a laboratory environment and tested for accuracy and dynamical behaviour in two biomass-fired heat-production units, one circulating fluidised-bed boiler (CFB) and one grate furnace. The results show that the method, which is easy to calibrate on site, can be used to predict the moisture content of the biomass fuel in the grate furnace with very good precision (<4% error). Furthermore, the method detects variations in moisture content of the furnace flue gases due to changes in the moisture content of the combusted fuel within the order of seconds. Since the transport time of the flue gases from the furnace to the measurement position is of the same order of magnitude, the total time for detection of a change in the moisture content of the fuel is small enough for the signal to be used to control both the fuel feed and the combustion air in a grate furnace. 相似文献
106.
Satciety is a distributed parallel satisfiability (SAT) solver which focuses on tackling the domain-specific problems inherent to
one of the most challenging environments for parallel computing—Peer-to-Peer Desktop Grids. Satciety efficiently addresses issues related to resource volatility and heterogeneity, limited node and network capabilities, as
well as non-uniform communication costs. This is achieved through a sophisticated distributed task pool execution model, problem
size reduction through multi-stage SAT formula preprocessing, context-aware memory management, and adaptive topology-aware
distributed dynamic learning. Despite the demanding conditions prevailing in Desktop Grids, Satciety achieves considerable speedups compared to state-of-the-art sequential SAT solvers. 相似文献
107.
Die Dynamik der Technikentwicklung in den vergangenen Jahren konfrontiert Datenschützer immer wieder aufs Neue mit Risiken
für die Privatsph?re der Betroffenen — und es sieht so aus, als ob sich dies in den n?chsten Jahren und Jahrzehnten nicht
?ndern wird. Konzepte für einen lebenslangen Datenschutz erfordern ein Umdenken vom kurzatmigen Systementwurf zu langfristigen
und zukunftsf?higen Planungen. 相似文献
108.
Mladen Brnčić Tomislav Bosiljkov Marko Ukrainczyk Branko Tripalo Suzana Rimac Brnčić Sven Karlović Damir Karlović Damir Ježek Dražen Vikić Topić 《Food and Bioprocess Technology》2011,4(7):1296-1306
Production of extrudates from cereals is an often-used technological process in today’s world food industry. Extrudates from
corn flour produced using the twin-screw extrusion process and enriched with whey protein concentrate represent high-quality
source of proteins and fats. Whey protein concentrate (WPC) as a valuable source of proteins and minerals is one of the highest-quality
components for possible extrudate enrichment. In this paper, the influence of various WPC addition and some extrusion process
parameters such as feed moisture content (
Q\textH\text2 \textO Q_{{{\text{H}}_{\text{2}} {\text{O}}}} ) on physicochemical properties of directly expanded corn flour extrudates manufactured in twin-screw co-rotating extruder
was investigated. Whey protein concentrate was added in the following ratios 7.5%, 15% and 22.5% and water in 10.08, 12.18
and 14.28 L/h. Final composition of products is determined with measuring of protein, fat and water shares, water absorption
index (WAI) and water solubility index (WSI). With added WPC and with increase of water volume flow, there was a significant
rise in total protein, fat and water content in final products, as well as lowering of WSI and rising of WAI indexes. The
statistical analysis of the obtained data shows that the lowest WSI and the highest WAI had samples with the largest share
of WPC (22.5%) and water volume flow of 14.28 L/h. Colour is measured for each sample, and results were represented with hue
angle (H), chroma (C) and lightness (L) values. Process parameters, WPC and
Q\textH\text2 \textO Q_{{{\text{H}}_{\text{2}} {\text{O}}}} influence the increase of saturation of C and lightness of L colour value, while H value stays unchanged. Mean value of H
was 90.14 ± 1.06, which corresponds to dominance of yellow colour of samples. 相似文献
109.
The demand for biofuel pellets has increased considerably in recent years, causing shortage of the traditional raw materials sawdust and wood shavings. In this study, the costs and energy requirements for the production of pellets from agricultural raw materials were analysed. The materials studied were Salix, reed canary grass, hemp, straw, screenings, rape-seed meal, rape cake and distiller’s waste. Four production scales were analysed, having an annual output of 80,000, 8000, 800 and 80 tonnes of pellets per year. It was concluded that the raw materials of greatest interest were Salix and reed canary grass. They had competitive raw material costs and acceptable fuel properties and could be mixed with sawdust in existing large-scale pelleting factories. Straw had low production costs but can cause serious ash-related problems and should, as also is the case for screenings, be avoided in small-scale burners. Hemp had high raw material costs and is of less commercial interest, while distiller’s waste, rape-seed meal and rape cake had higher alternative values when used as protein feed. The scale of production had a crucial influence on production costs. The machinery was used much more efficiently in large-scale plants, resulting in clear cost savings. Small-scale pelleting, both static and mobile, required cheap raw materials, low labour costs and long utilisation times to be profitable. In most cases, briquetting would be more commercially viable. The energy use in manufacturing pellets from air-dried crops was generally no higher than when moist sawdust was used as the raw material. 相似文献
110.
Klaus Timmel Sven Eckert Gunter Gerbeth 《Metallurgical and Materials Transactions B》2011,42(1):68-80
This article describes laboratory experiments aimed at investigations of flow structures and related transport processes in
the continuous-casting mold under the influence of an external direct current (DC) magnetic field. The main value of cold
metal laboratory experiments consists in the capabilities to obtain quantitative flow measurements with a reasonable spatial
and temporal resolution. The experimental results presented here were obtained using a physical model operating with the room-temperature
alloy GaInSn. According to the concept of the electromagnetic brake, the impact of a DC magnetic field on the outlet flow
from the submerged entry nozzle (SEN) has been studied up to Hartmann numbers of approximately 400. The effect of the magnetic
field on the flow structure turned out to be complex. The flow measurements do not manifest a general braking effect, which
would be expected as an overall damping of the flow velocity and the related fluctuations all over the mold volume. Variations
of the wall conductivity showed a striking impact on the resulting flow structures. The experiments provide a substantial
database for the validation of respective numerical simulations. 相似文献