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141.
Tobias Nipkow 《Formal Aspects of Computing》1989,1(1):320-338
The subject of this paper is theorem proving based on rewriting and induction. Both principles are implemented as tactics within the generic theorem prover Isabelle. Isabelle's higher-order features enable us to go beyond first-order rewriting and express rewriting with conditionals, induction schemata, higher-order functions and program transformers. Applications include the verification and transformation of functional versions of insertion sort and quicksort. 相似文献
142.
Kristofer Fredin Erik M.J. Johansson Tobias Blom Maria Hedlund Stefan Plogmaker Hans Siegbahn Klaus Leifer Håkan Rensmo 《Synthetic Metals》2009,159(1-2):166-170
We describe a method to fill thin films of nanoporous TiO2 with solid organic hole-conducting materials and demonstrate the procedure specifically for use in the preparation of dye-sensitized solar cells. Cross-sections of the films were investigated by scanning electron microscopy and it was observed that a hot molten organic material fills pores that are 10 μm below the surface of the film. We characterized the incident photon to current conversion efficiency properties of the solid TiO2/organic dye/organic hole-conductor heterojunctions and the spectra show that the dye is still active after the melting process. 相似文献
143.
144.
Representation techniques are important issues when designing successful evolutionary algorithms. Within this field the use
of neutrality plays an important role. We examine the use of bit-wise neutrality introduced by Poli and López (2007) from a theoretical point of view and show that this mechanism only enhances mutation-based evolutionary algorithms if not
the same number of genotypic bits for each phenotypic bit is used. Using different numbers of genotypic bits for the bits
in the phenome we point out by rigorous runtime analyses that it may reduce the optimization time significantly. 相似文献
145.
In this contribution, we present our new adaptive Lattice Boltzmann implementation within the Peano framework, with special focus on nanoscale particle transport problems. With the continuum hypothesis not holding anymore on these small scales, new physical effects—such as Brownian fluctuations—need to be incorporated. We explain the overall layout of the application, including memory layout and access, and shortly review the adaptive algorithm. The scheme is validated by different benchmark computations in two and three dimensions. An extension to dynamically changing grids and a spatially adaptive approach to fluctuating hydrodynamics, allowing for the thermalisation of the fluid in particular regions of interest, is proposed. Both dynamic adaptivity and adaptive fluctuating hydrodynamics are validated separately in simulations of particle transport problems. The application of this scheme to an oscillating particle in a nanopore illustrates the importance of Brownian fluctuations in such setups. 相似文献
146.
Liv Furuberg Michal Mielnik Anja Gulliksen Lars Solli Ib-Rune Johansen Jörg Voitel Tobias Baier Lutz Riegger Frank Karlsen 《Microsystem Technologies》2008,14(4-5):673-681
We present results from the MicroActive project which develops an instrument for molecular diagnostics. The instrument is
first tested for patient screening for a group of viruses causing cervical cancer. Two disposable polymer chips with reagents
stored on-chip are developed and will be inserted into the instrument for each patient sample analysis. The first chip will
perform nucleic acid extraction from patient epithelial cervical cells, while mRNA amplification and fluorescent detection
takes place in the second chip. This paper reports results on the amplification chip. Purified sample is inserted into the
chip and split into ten smaller droplets for simultaneous amplification and detection of ten viruses. The droplets move in
parallel channels, each with two chamber extensions containing dried reagents. Experimental results on parallel droplet movement
using one external pump combined with hydrophobic restrictions show that the parallel droplet positions can be controlled.
There are four valves with increasing burst pressures between 800 and 4,500 Pa in each parallel channel, positioning the droplets
in metering zones and reaction chambers. The re-hydration times for the dried reagents in micro chambers have been monitored.
After sample insertion, uniform concentration of the reagents in the droplet was reached after respectively 60 s and 10 min.
These times are acceptable for successful amplification. Finally we show positive amplification of HPV type 16 viruses in
a micro chamber. 相似文献
147.
JD Tobias 《Canadian Metallurgical Quarterly》1997,44(12):1320-1321
148.
Albert Albers Tobias Deigendesch Hans-Georg Enkler Stefan Hauser Pablo Leslabay Jochen Oerding 《Microsystem Technologies》2008,14(12):1781-1787
Miniaturization of macroscopic mechanical systems enables the opening of new areas of application for micro technological
systems. Because of technological restrictions, especially when applying miniaturized conventional manufacturing techniques,
shape and material deviations cannot be scaled down in the same dimension like micro parts. Thus, the long-term objective
is to ensure the functioning by appropriate design measures. In doing so, determination of the transfer behavior by modeling
and simulation is required. This work presents two ways for ensuring the required properties of micro gears and describes
how the results do correlate. The experimental way uses the radial composite inspection as it is used in the macroscopic world.
The simulative way deploys a rolling simulation by utilization of finite element analysis. The virtual prototypes are originated
on measured real test gears. When comparing experiment and simulation of the rolling behavior, in some short and long wave
areas deviations can be recognized. These can be ascribed to the reduction from three to two dimensions when modeling. Other
deviations might be based on inaccuracies when mounting into the test rig. In other areas quite good correlations of test
and simulation could be ascertained. 相似文献
149.
Tobias Kiesewetter Yvonne Tomm Manuela Turrin Helmut Tributsch 《Solar Energy Materials & Solar Cells》1999,59(4):309
Layer-type microcrystalline powders of WS2, MoS2, WSe2 and MoSe2, which were tested for photoeffects with contact free microwave conductivity measurements, were incorporated into a nanostructured TiO2 matrix in an attempt to obtain macroscopic photocurrents. Even though only 10% of the microcrystals were found to be active in contact with an iodide/iodine solution, photocurrents of the order of 100 μA/cm2 to 1 mA/cm2 were measured. The photoelectrochemical behavior of microcrystals was studied with space resolved photocurrent and photovoltage measurement techniques and it was attempted to understand the mechanism of current generation via the TiO2/microcrystal/electrolyte interaction. Critical and still unresolved problems are recognized to be the control and optimization of photoeffects in microcrystals and the adjustment of doping levels of the two material faces. Only small photopotentials could be observed up to now, probably due to an insufficient and inhomogeneous doping of microcrystals. More research will be needed to determine whether this strategy could lead to realistic photovoltaic systems. 相似文献
150.
Uwe Klammert Elke Vorndran Tobias Reuther Frank A. Müller Katharina Zorn Uwe Gbureck 《Journal of materials science. Materials in medicine》2010,21(11):2947-2953
Synthetic bone replacement materials are of great interest because they offer certain advantages compared with organic bone
grafts. Biodegradability and preoperative manufacturing of patient specific implants are further desirable features in various
clinical situations. Both can be realised by 3D powder printing. In this study, we introduce powder-printed magnesium ammonium
phosphate (struvite) structures, accompanied by a neutral setting reaction by printing farringtonite (Mg3(PO4)2) powder with ammonium phosphate solution as binder. Suitable powders were obtained after sintering at 1100°C for 5 h following
20–40 min dry grinding in a ball mill. Depending on the post-treatment of the samples, compressive strengths were found to
be in the range 2–7 MPa. Cytocompatibility was demonstrated in vitro using the human osteoblastic cell line MG63. 相似文献