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61.
Niskanen I Räty J Myllylä R Sutinen V Matsuda K Homma K Silfsten P Peiponen KE 《Applied spectroscopy》2012,66(7):786-790
We describe a method to determine the wavelength-dependent refractive index of liquids by measurement of light transmittance with a spectrophotometer. The method is based on using roughened glass slides with different a priori known refractive indices and immersing the slides into the transparent liquid with unknown refractive index. Using the dispersion data on the glass material it is possible to find the index match between the liquid and the glass slide, and hence the refractive index of the liquid. 相似文献
62.
63.
Ravazzani P Ruohonen J Tognola G Anfosso F Ollikainen M Ilmoniemi RJ Grandori F 《IEEE transactions on bio-medical engineering》2002,49(5):463-471
Magnetic stimulation of the nervous system is a non-invasive technique with a large number of applications in neurological diagnosis, brain research, and, recently, therapy. New applications require engineering modifications in order to decrease power consumption and coil heating. This can be accomplished by optimized coils with minimized resistance. In this study the influence of some frequency-related effects (skin and proximity effect) on the coil resistance will be discussed, together with the role played by wire shape, wire section, and twisting effect. The results show that the coil resistance increases with frequency. As an example, for a 20-mm2 circular wire section, the skin effect in the typical frequency range of magnetic stimulator devices (2-4 kHz) increases the coil resistance up to about 45% with respect to its dc value. Moreover, the influence of the frequency is lower for flat wire sections and reasonably small helix twist angle of the coil. 相似文献
64.
On the 23 March 2018, the most recent developments of the environmental impact assessment (EIA) law were examined by experts in Helsinki. The main theme of the conference was the comparison of the implementation experiences of various countries concerning the reformed EU EIA Directive. The European EIA debate was reflected against experiences in Canada. This paper examines the key points of the conference presentations and the lessons of the event. 相似文献
65.
This paper deals with wireless ATM and in particular with MAC (Medium Access Control) mechanisms. The requirements for wireless ATM MAC are discussed, and contentionbased and TDMA/reservation based MAC protocols are compared. The objective is to find out the suitability of current wireless MAC schemes for ATM interworking, in comparison to new wireless ATM MAC proposals. Two candidate mechanisms, EYNPMA used in HIPERLAN type 1, and a modified MDR protocol, are discussed in more detail and their performance in different traffic scenarios is evaluated through simulations. 相似文献
66.
Mika Ala-Korpela Jussi-Pekka Usenius Jyrki Keisala Aad van den Boogaart Pauli Vainio Jukka Jokisaari Seppo Soimakallio Risto Kauppinen 《Magma (New York, N.Y.)》1995,3(3-4):129-136
We present here a combination of time-domain signal analysis procedures for quantification of human brainin vivo
1H NMR spectroscopy (MRS) data. The method is based on a separate removal of a residual water resonance followed by a frequency-selective time-domain line-shape fitting analysis of metabolite signals. Calculation of absolute metabolite concentrations was based on the internal water concentration as a reference. The estimated average metabolite concentrations acquired from six regions of normal human brain with a single-voxel spin-echo technique for theN-acetylaspartate, creatine, and choline-containing compounds were 11.4±1.0,6.5±0.5, and 1.7±0.2 mmol kg–1 wet weight, respectively. The time-domain analyses ofin vivo
1H MRS data from different brain regions with their specific characteristics demonstrate a case in which the use of frequency-domain methods pose serious difficulties. 相似文献
67.
Neural networks can be evolved to control robot manipulators in tasks like target tracking and obstacle avoidance in complex
environments. Neurocontrollers are robust to noise and can be adapted to different environments and robot configurations.
In this paper, neurocontrollers were evolved to position the end effector of a robot arm close to a target in three different
environments: environments without obstacles, environments with stationary obstacles, and environments with moving obstacles.
The evolved neurocontrollers perform qualitatively like inverse kinematic controllers in environments with no obstacles and
like path-planning controllers based on Rapidly-exploring random trees in environments with obstacles. Unlike inverse kinematic
controllers and path planners, the approach reliably generalizes to environments with moving obstacles, making it possible
to use it in natural environments. 相似文献
68.
69.
This paper focuses on structural optimization of the so-called pumping kite wind generator whose operating principle consists in mechanically driving a ground-based electric generator by means of tethered kites. The employed mathematical model of the kite wind generator is based on the refined crosswind motion law derived under the assumption of equilibrium motion of the kite. The resulting simple approximate analytical formula for the mean mechanical power generated by the deploying kite is used for the constrained structural optimization of the pumping kite wind generator maximizing its electrical power output by adjusting the key structural parameters of the kite wind generator. 相似文献
70.
A total of 330 bee honey samples was analysed in 1986-1990, and the results are reported. Analysis was performed according to the method for the amitraz total residue determination by hydrolysis and steam distillation as described. 60% of the honeys were practically not contamined (total residue content amounting to 0.01 mg/kg), 8.5% of the honeys contained more than 0.05 mg/kg. Maximal values of 0.2-0.5 mg/kg were stated. 54% of the rape-honeys contained more than 0.01 mg/kg, 19% more than 0.05 mg/kg. 相似文献