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排序方式: 共有262条查询结果,搜索用时 15 毫秒
61.
Olli Varis 《国际水资源开发杂志》2007,23(3):519-535
The pressure to shift increasingly to renewable energy sources is escalating. The Johannesburg World Summit of Sustainable Development of 2002 defined in its Plan of Implementation that the global share of renewable energy sources should be increased substantially. Today, renewables account for 13.1% of the world's primary energy production. Eighty per cent of all renewable energy comes from biomass and 16% from hydropower. These two sources will thus be set under particular growth pressure in future years. This paper assesses the water needs of current and future bioenergy production and concludes that it is one of the major water consumers of this planet, although much neglected in global water assessments. The pressure to increase the share of bioenergy in the global account puts a considerable strain on water resources in all continents, but the challenges will be most pronounced in Asia and Africa. 相似文献
62.
Timo Knuutila Mika Hirvikorpi Mika Johnsson Olli Nevalainen 《International Journal of Flexible Manufacturing Systems》2004,16(2):151-167
A variant of the classical job grouping problem (JGP) in printed circuit board (PCB) assembly is considered. Studies on JGPs have assumed a single feeder from which the components are retrieved and then placed on the PCB. Recent advances in technology have made it possible to use several different kinds (types) of feeders at the same time. In a JGP, the aim is to group the PCBs so that the cardinality of the grouping is minimal and each group can be processed without rearranging the contents of the feeder. In the job grouping problem with several feeder types (JGP-T) the goal is the same but instead of one linear feeder we have several feeders and each component is associated with a given feeder type which restricts its placement. We give a mathematical formulation for the JGP-T and show that it is hard to solve to optimality for problems of practical size. The connections of JGP-T to known problems are discussed. We also propose several efficient heuristics and compare their results against optimal solutions. 相似文献
63.
Olli Ant-Wuorinen 《Zeitschrift für Lebensmitteluntersuchung und -Forschung A》1935,70(5):389-391
Ohne Zusammenfassung 相似文献
64.
Petra S.Pálvölgyi Daniel Sebők Imre Szenti Eva Bozo Henri Ervasti Olli Pitkänen Jari Hannu Heli Jantunen Marko E.Leinonen Sami Myllymäki Akos Kukovecz Krisztian Kordas 《Nano Research》2021,14(5):1450-1456
In the next generation wireless communication systems operating at near terahertz frequencies, dielectric substrates with the lowest possible permittivity and loss factor are becoming essential. In this work, highly porous (98.9% ± 0.1%) and lightweight silica foams (0.025 ± 0.005 g/cm3), that have extremely low relative permittivity (εr = 1.018 ± 0.003 at 300 GHz) and corresponding loss factor (tan δ< 3 × 10?4 at 300 GHz) are synthetized by a template-assisted sol-gel method. After dip-coating the slabs of foams with a thin film of cellulose nanofibers, sufficiently smooth surfaces are obtained, on which it is convenient to deposit electrically conductive planar thin films of metals important for applications in electronics and telecommunication devices. Here, micropatterns of Ag thin films are sputtered on the substrates through a shadow mask to demonstrate double split-ring resonator metamaterial structures as radio frequency filters operating in the sub-THz band. 相似文献
65.
Olli H. Pakarinen Flyura Djurabekova Kai Nordlund 《Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms》2010,268(19):3163-3166
Swift heavy ion irradiation leaves a latent ion track around the ion path in many materials. Here we report computational molecular dynamics (MD) simulation results on track formation in several insulating materials, quartz, amorphous silica (a-SiO2), zinc oxide and diamond, concentrating especially in mass transport leading to density variations in the track volume during the initial stages of track formation. These details are largely unobservable in experiments due to the picosecond timescale and very local nature, and also in many computational models of track formation. Earlier a low-density core - high-density shell fine structure has been observed in latent tracks in amorphous silica, and here we study if other materials than silica show similar behavior. The results highlight the dynamical nature of track formation, that includes competing effects of heat and mass transport, rapid quenching of the heated area and recrystallization. 相似文献
66.
Aittokallio T Malminen JS Pahikkala T Polo O Nevalainen OS 《Computer methods and programs in biomedicine》2007,85(1):8-18
We describe an automated method for monitoring airflow dynamics in the upper airway of a sleeping subject. Its main task is to determine a set of inspiratory flow shape representatives and their relative incidence in a given respiratory airflow material. The flow shape clustering aims at reducing redundant information in the data, and thereby decreases the time needed to score overnight sleep recordings. Compared with previous computer-assisted systems, built on a pre-defined classification of prototype shapes, we require no a priori assumptions of the flow shape clusters to be discovered. The intrinsic flow shape clustering is performed with a modification of the Isodata algorithm, and the K-means clustering is used as a reference in comparison studies. The operation of the method is demonstrated on clinical sleep recordings both from patients with nocturnal breathing disorders and from non-symptomatic individuals. The feasible results obtained in the practical research design suggest that application of clustering algorithms to respiratory airflow measurements could give important insights into the subtle flow shape abnormalities underlying obstructive sleep-disordered breathing. 相似文献
67.
Anjana?SarkarEmail author Eduardo?Gracia-Espino Thomas?W?gberg Andrey?Shchukarev Melinda?Mohl Anne-Riikka?Rautio Olli?Pitk?nen Tiva?Sharifi Krisztian?Kordas Jyri-Pekka?MikkolaEmail author 《Nano Research》2016,9(7):1956-1968
Nanosized metal (Pt or Pd)-decorated TiO2 nanofibers (NFs) were synthesized by a wet impregnation method. CdSe quantum dots (QDs) were then anchored onto the metal-decorated TiO2 NFs. The photocatalytic performance of these catalysts was tested for activation and reduction of CO2 under UV-B light. Gas chromatographic analysis indicated the formation of methanol, formic acid, and methyl formate as the primary products. In the absence of CdSe QDs, Pd-decorated TiO2 NFs were found to exhibit enhanced performance compared to Pt-decorated TiO2 NFs for methanol production. However, in the presence of CdSe, Pt-decorated TiO2 NFs exhibited higher selectivity for methanol, typically producing ~90 ppmg?1·h?1 methanol. The CO2 photoreduction mechanism is proposed to take place via a hydrogenation pathway from first principles calculations, which complement the experimental observations. 相似文献
68.
Lorite Gabriela S. Ylä-Outinen Laura Janssen Lauriane Pitkänen Olli Joki Tiina Koivisto Janne T. Kellomäki Minna Vajtai Robert Narkilahti Susanna Kordas Krisztian 《Nano Research》2019,12(11):2894-2899
Nano Research - New strategies for spatially controlled growth of human neurons may provide viable solutions to treat and recover peripheral or spinal cord injuries. While topography cues are known... 相似文献
69.
Matti Nykänen Raul Hakli Satu Eloranta Olli Niinivaara 《Annals of Mathematics and Artificial Intelligence》2016,78(3-4):323-360
We tackle the problem that arises when an agent receives unbelievable information. Information is unbelievable if it conflicts with the agent’s convictions, that is, what the agent considers knowledge. We propose two solutions based on modifying the information so that it is no longer unbelievable. In one solution, the source and the receiver of the information cooperatively resolve the conflict. For this purpose we introduce a dialogue protocol in which the receiver explains what is wrong with the information by using logical interpolation, and the source produces a new assertion accordingly. If such cooperation is not possible, we propose an alternative solution in which the receiver revises the new piece of information by its own convictions to make it acceptable. 相似文献
70.
Miguel Bordallo López Jari Hannuksela Olli Silvén Markku Vehviläinen 《Multimedia Tools and Applications》2014,69(1):31-51
The small size of handheld devices, their video capabilities and multiple cameras are under-exploited assets. Properly combined, the features can be used for creating novel applications that are ideal for pocket-sized devices, but may not be useful in laptop computers, such as interactively capturing and analyzing images on the fly. In this paper we consider building mosaic images of printed documents and natural scenes from low resolution video frames. High interactivity is provided by giving a real-time feedback on the video quality, while simultaneously guiding the user’s actions. In our contribution, we analyze and compare means to reach interactivity and performance with sensor signal processing and GPU assistance. The viability of the concept is demonstrated on a mobile phone. The achieved usability benefits suggest that combining interactive imaging and energy efficient high performance computing could enable new mobile applications and user interactions. 相似文献