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1.
A. Biedunkiewicz N. Gordon J. Straszko S. Tamir 《Journal of Thermal Analysis and Calorimetry》2007,88(3):717-722
Results of research work on oxidation of TiC/C nano-composites in air and under non-isothermal conditions are presented.
The oxidation of nano-crystalline titanium carbide as well as its carbon composites were studied using TG-DSC method in dry
air atmosphere. The investigated samples were as follows: commercial TiC nano-powders from Alfa Aesar (80 nm) and carbon composites
including nano-crystalline TiC (30 nm and 50, 10, 3 mass% of carbon in matrix). The measurements were executed in the Setaram
thermoanalyser TG-DSC 92-15 in non-isothermal conditions, with mass samples of 30±0.2 mg and constant heating rate in the
range 2–10 K min−1. 相似文献
2.
3.
Arie Tamir 《Mathematical Programming》1993,62(1-3):475-496
In the classicalp-center location model on a network there is a set of customers, and the primary objective is to selectp service centers that will minimize the maximum distance of a customer to a closest center. Suppose that thep centers receive their supplies from an existing central depot on the network, e.g. a warehouse. Thus, a secondary objective is to locate the centers that optimize the primary objective as close as possible to the central depot. We consider tree networks and twop-center models. We show that the set of optimal solutions to the primary objective has a semilattice structure with respect to some natural ordering. Using this property we prove that there is ap-center solution to the primary objective that simultaneously minimizes every secondary objective function which is monotone nondecreasing in the distances of thep centers from the existing central depot.Restricting the location models to a rooted path network (real line) we prove that the above results hold for the respective classicalp-median problems as well. 相似文献
4.
Synthesis and Characterization of Flexible Hydrogel Electrodes for Electrochemical Impedance Measurements of Protective Coatings on Metal Sculptures 下载免费PDF全文
A novel conductive anionic hydrogel was synthesized for use as a solid electrolyte for electrochemical impedance spectroscopy (EIS) characterization of the barrier properties of protective coatings on outdoor metalworks, such as bronze sculptures. The AMPS‐co‐PAA hydrogel was soaked in a variety of aqueous salt solutions and characterized by swelling capacity and conductivity in order to determine the most appropriate gel/liquid electrolyte combination for use on culturally significant objects. K2PIPES‐equilibrated hydrogels were selected as the preferred electrodes for this particular application and were used to measure the impedance of a coated substrate, yielding spectra similar to those from standard liquid cells. 相似文献
5.
The lateral shift of both the reflected and the transmitted beams are examined for incidence on layered configurations. In particular, beam displacements are evaluated at a layer placed between two different semi-infinite media. We find that the reflected beam may undergo a large displacement, which occurs in either a forward or a backward direction. The transmitted beam is also substantially displaced, but its shift occurs in a forward direction only. 相似文献
6.
7.
T. Tamir 《Applied Physics A: Materials Science & Processing》1981,25(3):201-210
Guided-wave methods used in the past to treat electromagnetic problems and applications in the microwave area have recently
been extended to cover work in fiber and integrated optics. The basic principles of these methods are reviewed briefly and,
in particular, the “open” properties of optical configurations are contrasted to the “closed” characteristics that describe
most microwave applications. These aspects are illustrated in the context of beam couplers of uniform and periodic varieties,
which are shown to lend themselves to rigorous treatment by microwave guided-wave methods that include both theoretical and
experimental facets. 相似文献
8.
At room temperature and below, the proton NMR spectrum of N-(trideuteriomethyl)-2-cyanoaziridine consists of two superimposed ABC patterns assignable to two N-invertomers; a single time-averaged ABC pattern is observed at 158.9°C. The static parameters extracted from the spectra in the temperature range from –40.3 to 23.2°C and from the high-temperature spectrum permit the calculation of the thermodynamic quantities ΔH0 = ?475±20 cal mol?1 (?1.987 ± 0.084 kJ mol?1) and ΔS0 = 0.43±0.08 cal mol?1 K?1 (1.80±0.33 J mol?1 K?1) for the cis ? trans equilibrium. Bandshape analysis of the spectra broadened by non-mutual three-spin exchange in the temperature range from 39.4–137.8°C yields the activation parameters ΔHtc≠ = 17.52±0.18 kcal mol?1 (73.30±0.75 kJ mol?1), ΔStc≠ = ?2.08±0.50 cal mol?1 K?1 (?8.70±2.09 J mol?1 K?1) and ΔGtc≠ (300 K) = 18.14±0.03 kcal mol?1 (75.90±0.13 kJ mol?1) for the trans → cis isomerization. An attempt is made to rationalize the observed entropy data in terms of the principles of statistical thermodynamics. 相似文献
9.
Costa et al. (Oper. Res. Lett. 31:21–27, 2003) presented a quadratic O(min (Kn,n
2)) greedy algorithm to solve the integer multicut and multiflow problems in a rooted tree. (n is the number of nodes of the tree, and K is the number of commodities). Their algorithm is a special case of the greedy type algorithm of Kolen (Location problems
on trees and in the rectilinear plane. Ph.D. dissertation, 1982) to solve weighted covering and packing problems defined by general totally balanced (greedy) matrices. In this communication
we improve the complexity bound in Costa et al. (Oper. Res. Lett. 31:21–27, 2003) and show that in the case of the integer multicut and multiflow problems in a rooted tree the greedy algorithm of Kolen
can be implemented in subquadratic O(K+n+min (K,n)log n) time. The improvement is obtained by identifying additional properties of this model which lead to a subquadratic transformation
to greedy form and using more sophisticated data structures.
相似文献
10.
We study the Tardos’ probabilistic fingerprinting scheme and show that its codeword length may be shortened by a factor of
approximately 4. We achieve this by retracing Tardos’ analysis of the scheme and extracting from it all constants that were
arbitrarily selected. We replace those constants with parameters and derive a set of inequalities that those parameters must
satisfy so that the desired security properties of the scheme still hold. Then we look for a solution of those inequalities
in which the parameter that governs the codeword length is minimal. A further reduction in the codeword length is achieved
by decoupling the error probability of falsely accusing innocent users from the error probability of missing all colluding
pirates. Finally, we simulate the Tardos scheme and show that, in practice, one may use codewords that are shorter than those
in the original Tardos scheme by a factor of at least 16.
相似文献