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21.
Hybrid finite-element method for discretising cylindrically symmetric parts in electrotechnical models 总被引:1,自引:0,他引:1
In many technical devices such as transformers and electrical machines, large differences in geometric dimensions are observed. As a consequence, the generation of a 3D computational grid for the whole device leads to unacceptably large numbers of elements or can even fail. In addition to the commonly applied cartesian or cylindrical symmetries of the overall geometry, the model can be subdivided into parts featuring translational or cylindrical symmetries. Such parts are discretised separately, accounting for the local symmetry, and are then combined with the surrounding 3D model. Excitations and boundary conditions of the submodels are not necessarily symmetric but are expected to be smooth in the direction of the symmetry. Then, the field distribution at the interface is well approximated by a set of spectral elements along the dimension of symmetry. Coupling between the model parts is carried out by means of Lagrange multipliers. A single-phase transformer with thin insulation sheets is taken as an example to illustrate the proposed hybrid discretisation. The cross-section of the cylindrically symmetric part containing thin sheets, is represented by a fine 2D finite-element mesh so that all the geometrical details can be resolved, and the rest of the structure is discretised by a 3D mesh. Nevertheless, a fully 3D field distribution is calculated in all model parts. Only a small number of harmonic functions is needed to account for the azimuthal field variation at the cylindrical interface. Hence, the number of unknowns in the numerical model is reduced significantly, while a high level of accuracy is maintained 相似文献
22.
The authors report measurements of the α-factor and linewidth of DBR (distributed Bragg reflector) lasers fabricated with weak grating constants. Such devices exhibit detuned-loading effects, and the measured values depend strongly on the tuning current of the Bragg section. α-factor behavior is found to agree with earlier theoretical predictions. Linewidth behavior is shown to be dominated by carrier shot noise in the tuning section. A theoretical analysis of the DBR laser is outlined including detuned loading and carrier shot noise effect 相似文献
23.
Pilot experiments with electrodialysis and ozonation for the production of a fertiliser from urine. 总被引:1,自引:0,他引:1
W Pronk S Zuleeg J Lienert B Escher M Koller A Berner G Koch M Boller 《Water science and technology》2007,56(5):219-227
Pilot tests were performed with a process combination of electrodialysis and ozonation for the removal of micropollutants and the concentration of nutrients in urine. In continuous and batch experiments, maximum concentration factors up to 3.5 and 4.1 were obtained, respectively. The desalination capacity did not decrease significantly during continuous operation periods of several weeks. Membrane cleaning after 195 days resulted in approximately 35% increase in desalination rate. The Yeast Estrogen Screen (YES), a bioassay that selectively detects oestrogenic compounds, confirmed that about 90% of the oestrogenic activity was removed by electrodialysis. HPLC analysis showed that ibuprofen was removed to a high extent, while other micropollutants were below the detection limit. In view of the fact that ibuprofen is among the most rapidly transported micropollutants in electrodialysis processes, this result indicates that electrodialysis provides an effective barrier for micropollutants. Standardised plant growth tests were performed in the field with the salt solution resulting from the treatment by electrodialysis and subsequent ozonation. The results show that the plant height is comparable to synthetic fertilisers, but the crop yield is slightly lower. The latter is probably caused by volatilisation losses during field application, which can be prevented by improved application technologies. 相似文献
24.
Koch David Despotovic Miroslav Thaler Simon Zeppelzauer Matthias 《Applied Intelligence》2021,51(11):8106-8106
Applied Intelligence - A Correction to this paper has been published: https://doi.org/10.1007/s10489-021-02433-z 相似文献
25.
Gary Gibson Xia Sheng Dick Henze Si‐Ty Lam Patricia Beck Yoocharn Jeon Zhang‐Lin Zhou Brad Benson Qin Liu Gregg Combs Tim Koch Kent Biggs 《Journal of the Society for Information Display》2012,20(10):552-558
Reflective displays are advantageous in applications requiring low power or daylight readability. However, there are no low‐cost reflective technologies capable of displaying bright colors. By employing photoluminescence to more efficiently use ambient light, we created a prototype display that provides bright, full color in a simple, low‐cost architecture. This prototype includes a novel electrokinetic shutter, a layer that incorporates patterned luminescent red, green, and blue sub‐pixel elements, and a novel optical out‐coupling scheme. The luminescent elements convert otherwise‐wasted portions of the incident spectrum to light in the desired color band, resulting in improved color saturation and lightness. This prototype provides a color gamut that is superior to competing reflective display technologies that utilize color filters in single‐layer side‐by‐side sub‐pixel architectures. The current prototype is capable of switching in <0.5 s; future displays based on an alternative electro‐optic shutter technology should achieve video rate operation. A transflective version of this technology has also been prototyped. The transflective version utilizes its backlight with a power efficiency that is at least three times that of a conventional liquid crystal display. These photoluminescence‐based technologies enable a host of applications ranging from low‐power mobile products and retail pricing signage to daylight readable signage for outdoor advertising segments. 相似文献
26.
Mechanical alloying was used to synthesize NixZr1–x alloys from mixtures of intermetallic compound powders, and also from mixtures of intermetallic compound powders and pure elemental powders. The mechanically alloyed powders were amorphous in the range 0.24 x 0.85. This range is larger than amorphous alloys produced by the melt-spinning technique and mechanical alloying of elemental crystalline powders. Two-phase mixtures of the amorphous phase and the corresponding crystalline terminal solid solution were formed in the range 0.10 x 0.22, and x=0.90. It is found that the morphological development during mechanical alloying of these powders is different from mechanical alloying using only pure ductile crystalline elemental powders. The thermal stability has been investigated. The enthalpy and activation energy of crystallization for Ni-Zr amorphous powders prepared by mechanical alloying are lower than those for melt-spun samples of the same composition. The crystallization temperature of the mechanically alloyed Ni-Zr amorphous powders is higher than that of meltspun samples in the composition range Ni20Zr80 to Ni33Zr67 and Ni40Zr60 to Ni60Zr40. The presence of tiny crystallites as nucleation centres and high oxygen levels in the mechanically alloyed amorphous alloys might be responsible for the differences in crystallization behaviour. A new crystalline metastable phase was observed during crystallization studies of Ni24Zr76 amorphous powder. 相似文献
27.
Alexander Zimmermann Qais Z. Jaber Dr. Johannes Koch Steffen Riebe Dr. Cecilia Vallet Dr. Kateryna Loza Matthias Hayduk Dr. Kfir B. Steinbuch Prof. Shirley K. Knauer Prof. Micha Fridman Jun.-Prof. Jens Voskuhl 《Chembiochem : a European journal of chemical biology》2021,22(9):1563-1567
We report the characterization of amphiphilic aminoglycoside conjugates containing luminophores with aggregation-induced emission properties as transfection reagents. These inherently luminescent transfection vectors are capable of binding plasmid DNA through electrostatic interactions; this binding results in an emission “on” signal due to restriction of intramolecular motion of the luminophore core. The luminescent cationic amphiphiles effectively transferred plasmid DNA into mammalian cells (HeLa, HEK 293T), as proven by expression of a red fluorescent protein marker. The morphologies of the aggregates were investigated by microscopy as well as ζ-potential and dynamic light-scattering measurements. The transfection efficiencies using luminescent cationic amphiphiles were similar to that of the gold-standard transfection reagent Lipofectamine® 2000. 相似文献
28.
W. Stein H. Weiß O. Koch P. Neuhausen H. Baumann 《European Journal of Lipid Science and Technology》1970,72(11):956-959
Preparation of Esters of α-Sulfo-Fatty Acids A process for the continuous α-sulfonation of saturated fatty acid esters with SO3 was worked out and a special bleaching process was developed for these products. The conversion, i. e. the degree of sulfonation is of the order of 95–99%. Solvents, further processing steps or purification operations for the separation of by-products are not required. 相似文献
29.
Porosity in nanoporous ceramics produced by pyrolysis of organosilicon polymer at a temperature of 600°C was investigated using the BET method. Samples were molded from fractionated granules produced by single or double milling in a planetary mill of a polymer previously solidified and heat-treated at 200°C. Specific surface area depending on nanopores sharply decreases after the granules reach a size over 250 m in single milling and over 1000 m in double milling. An explanation for these facts is given in the context of synergism. 相似文献
30.
13C n.m.r. spectroscopy has been applied to investigate a number of coal tar and petroleum-derived carbon black feedstocks. Application of the J-modulated spin echo technique is especially rewarding, as this method renders the quaternary carbons directly detectable. Thus the quality of carbon black feedstocks can additionally be gauged on the basis of the contents of quaternary carbons, which is a direct indication of the carbon yield in the carbon black production process. 相似文献