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121.
122.
Because of package, a single FBG has dual Bragg wavelength. One is sensitive to stress and the other is sensitive to temperature. By using the special mechanism, the wavelengths can be tuned by stress and temperature respectively. 相似文献
123.
Surface free energy of a solid surface gives a direct measure of intermolecular interactions at interfaces and has a strong influence on adsorption and adhesion behaviour. However few data are available for the surface free energies of electroless Ni–P based composition coatings. In this paper, the electroless Ni–P, Ni–P-surfactant, Ni–Cu–P, Ni–P–PTFE and Ni–Cu–P–PTFE composite coatings were prepared under various coating conditions. The chemical compositions, surface morphology and thickness of the coatings were measured using an energy dispersive X-ray microanalysis (EDX), a scanning electron microscope (SEM) and a digital micrometer respectively. The contact angles of water, diiodomethane and ethylene glycol on the coatings were measured automatically using dataphysics OCA-20 contact angle analyser. The surface free energy of the coatings and their components (e.g. dispersion, polar or acid/base portions) were calculated using various methods. The experimental results showed that the incorporation of surfactant or PTFE particles into Ni–P matrixes has a significant influence on the surface free energy of the coatings, while the incorporation of copper into Ni–P matrixes has no significant influence on the surface free energy of the coatings. 相似文献
124.
The effects of partial substitution of Mn for Co on the thermoelectric properties of Ca3MnxCo4−xO9 (x=0, 0.03, 0.9), prepared by sol-gel process, were investigated at the temperatures from 380 K down to 5 K. The results indicate that the substitution of Mn for Co results in increase in thermopower at temperatures >∼80 K, and substantial (23-31% at 300 K) decrease in lattice thermal conductivity in the whole temperature range investigated. The temperature behavior of ZT suggests that Ca3MnxCo4−xO9 with light Mn substitution would be a promising candidate for high-temperature thermoelectric applications. 相似文献
125.
126.
Summary Our purpose is to extend results due to P. Chandra and L. Leindler concerning the order of approximation by means of Fourier series for functions belonging to generalized Lipschitz-classes. 相似文献
127.
Positron-lifetime experiments have been carried out on two undoped n-type liquid encapsulated Czochralski (LEC)-grown InP samples with different stoichiometric compositions in the temperature range 10-300 K. For temperatures below 120 K for P-rich InP and 100 K for In-rich InP, the positron average lifetime began to increase rapidly and then leveled off, which was associated with the charge state change of hydrogen indium vacancy complexes from (VInH4)+ to (VInH4)0. This phenomenon was more obvious in P-rich samples that have a higher concentration of VInH4. The transformation temperature of approximately 120 K suggests that the complex VInH4 is a donor defect and that the ionization energy is about 0.01 eV. The ionization of neutral VInH4 accounted for the decrease of the positron average lifetime when the sample was illuminated with a photon energy of 1.32 eV at 70 K. These results provide evidence for hydrogen complex defects in undoped LEC InP. 相似文献
128.
This work is devoted to near-optimal controls of large-scale discrete-time nonlinear dynamic systems driven by Markov chains; the underlying problem is to minimize an expected cost function. Our main goal is to reduce the complexity of the underlying systems. To achieve this goal, discrete-time control models under singularly-perturbed Markov chains are introduced. Using a relaxed control representation, our effort is devoted to finding near-optimal controls. Lumping the states in each irreducible class into a single state gives rise to a limit system. Applying near-optimal controls of the limit system to the original system, near-optimal controls of the original system are derived. 相似文献
129.
Hongyong Zhao 《Journal of Mathematical Analysis and Applications》2003,282(2):437-443
The paper is devoted to the invariant set and periodic attractor for nonautonomous functional differential systems. Some sufficient criteria of the invariant set and periodic attractor are derived. Particularly, we have provided an estimate on existence range of periodic attractor by using the properties of nonnegative matrices and differential inequality technique. 相似文献
130.
The properties of pulsed laser vapor doping on p-Si(1 0 0) with a KrF (248 nm) excimer pulsed laser (248 nm) and BCl3 gas are reported in this paper. The doped samples are characterized by the resistance measured using a four-probe method, since the sheet resistance changes with the carrier concentration of the sample. The doping effects with the variation of laser energy density, pulse number, and the pressure of BCl3 were investigated in terms of the sheet resistance. In this way, the optimized parameters were obtained and used for the positive heavy doping on p-Si(1 0 0) and p-Si(1 1 1). Then, using a square mesh under the above conditions, an image doping was completed. Finally, the metal–semiconductor Ohmic contacts were realized by plating Ag and Cu films on the doped surface. 相似文献