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951.
952.
Twin Paradox and the Logical Foundation of Relativity Theory 总被引:3,自引:0,他引:3
We study the foundation of space-time theory in the framework of first-order logic (FOL). Since the foundation of mathematics has been successfully carried through (via set theory) in FOL, it is not entirely impossible to do the same for space-time theory (or relativity). First we recall a simple and streamlined FOL-axiomatization Specrel of special relativity from the literature. Specrel is complete with respect to questions about inertial motion. Then we ask ourselves whether we can prove the usual relativistic properties of accelerated motion (e.g., clocks in acceleration) in Specrel. As it turns out, this is practically equivalent to asking whether Specrel is strong enough to “handle” (or treat) accelerated observers. We show that there is a mathematical principle called induction (IND) coming from real analysis which needs to be added to Specrel in order to handle situations involving relativistic acceleration. We present an extended version AccRel of Specrel which is strong enough to handle accelerated motion, in particular, accelerated observers. Among others, we show that~the Twin Paradox becomes provable in AccRel, but it is not provable without IND. 相似文献
953.
Ata N. Al-Hussaini 《Applied Mathematics and Optimization》1989,20(1):63-69
A simple proof is given for the stochastic integral representation of a Fréchet differentiable functional of the paths of a given diffusion process. The proof begins when the functional depends on one coordinate, then passes to (by appropriate conditioning) a perhaps more difficult case—when the functional depends on a finite number of coordinates—and finally, by approximation, to the general case. 相似文献
954.
In 1979, Papadimitriou and Yannakakis gave a polynomial time algorithm for the scheduling of jobs requiring unit completion times when the precedence constraints form an interval order. The authors solve here the corresponding problem, for preemptive scheduling (a job can be interrupted to work on more important tasks, and completed at a later time, subject to the usual scheduling constraints.) The m-machine preemptive scheduling problem is shown to have a polynomial algorithm, for both unit time and variable execution times as well, when the precedence constraints are given by an interval order. 相似文献
955.
956.
This paper examines the performance of Commodity Trading Advisors (CTAs) using fixed and variable benchmarking models. In
order to avoid the troublesome passive and active commodity and managed futures benchmarks (indices) when examining the performance
of CTAs, we innovate by using data envelopment analysis (DEA). Because this alternative class has non-linear returns due to
long/short positions, and derivatives (i.e., dynamic trading strategies), DEA can alleviate the problems usually associated
with these indices. The effectiveness of using benchmarking models in a DEA setting will provide investors with an alternative
technique in assessing the performance and identifying efficient CTAs. 相似文献
957.
Three design techniques for stability analysis of longitudinally corrugated cylindrical shells are examined. The first two account for the true geometry of the shell and the third one replaces the corrugated shell with an equivalent orthotropic shell using reduction formulas. The exact formulations employ classical and Timoshenko-type theories. The techniques are analyzed by an example of sinusoidally corrugated shells. It is shown that the exact formulation permits finding practically important relations for corrugation parameters, which raises considerably the specific critical loads. 相似文献
958.
V. A. Astapenko A. S. Kubankin N. N. Nasonov V. V. Polyanskiĭ G. P. Pokhil V. I. Sergienko V. A. Khablo 《JETP Letters》2006,84(6):281-284
The spectra of the collimated polarization bremsstrahlung of 7-MeV electrons intersecting Al, Cu, and Ni polycrystalline films have been measured. Detailed quantitative comparison of the experimental data with theoretical predictions has been performed. It has been shown that the model of a polycrystal as an ensemble of randomly oriented single crystals adequately describes the experimental results. This makes it possible to expect the development of a new method of diagnostics of the atomic structure of partially ordered solids. 相似文献
959.
V. V. Shelkovnikov Z. M. Ivanova N. A. Orlova T. N. Gerasimova A. I. Plekhanov 《Optics and Spectroscopy》2002,92(6):884-891
The formation and properties of J-aggregates in thin solid films of pseudoisocyanines with long N-alkyl groups, obtained by centrifuging from solutions in organic solvents, were studied. It is shown for the first time that nonsymmetric cyanine dyes, containing a C2H5 group at one nitrogen atom and a C10H21, C15H31, or C18H37 group at another nitrogen atom, spontaneously form J-aggregates stable at room temperature and pressing a narrow absorption band with a half-width at half maximum of 200 cm?1. The thermal stability of J-aggregates in thin films of pseudoisocyanines with alkyl substituents decreases in the following order: C2H5-C2H5> C2H5-C6H13>C2H5-C18H37>C2H5-C10H21>C2H5-C15H31. By introducing 1-octadecyl-2-methylquinolinium iodide in the film, it was found that the J-aggregates studied consist of a small number (2–4) of dye molecules. 相似文献
960.
Y. Fukuda T. Kobayashi H. Yoshida T. Sekizawa N. Sanada 《Applied Surface Science》2002,190(1-4):279-283
Adsorption and decomposition of triethylindium (TEI: (C2H5)3In) on a GaP(0 0 1)-(2×1) surface have been studied by low-energy electron diffraction (LEED), Auger electron spectroscopy (AES), temperature-programmed desorption (TPD) and high-resolution electron energy loss spectroscopy (HREELS). It is found from the TPD result that ethyl radical and ethylene are evolved at about 300–400 and 450–550 K, respectively, as decomposition products of TEI on the surface. This result is quite different from that on the GaP(0 0 1)-(2×4) surface. The activation energy of desorption of ethyl radical is estimated to be about 93 kJ/mol. It is suggested that TEI is adsorbed molecularly on the surface at 100 K and that some of TEI molecules are dissociated into C2H5 to form P–C2H5 bonds at 300 K. The vibration modes related to ethyl group are decreased in intensity at about 300–400 and 450–550 K, which is consistent with the TPD result. The TEI molecules (including mono- and di-ethylindium) are not evolved from the surface. Based on the TPD and HREELS results, the decomposition mechanism of TEI on the GaP(0 0 1)-(2×1) surface is discussed and compared with that on the (2×4) surface. 相似文献