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21.
The semiconducting lanthanide cuprates Pr2CuO4, Nd2CuO4, and Gd2CuO4 have been investigated using X-ray diffraction, magnetic susceptibility, and electron paramagnetic resonance techniques. The susceptibility and resonance studies indicate that the Cu2+ ions are ordered antiferromagnetically and that the exchange interactions involving the Ln3+ ions are relatively weak. The deviations from the Curie-Weiss law in Pr2CuO4 and Nd2CuO4 are in qualitative agreement with the predicted behavior for isolated Ln3+ ions under the influence of a crystal field. Hence these compounds provide interesting examples of planar Cu2+-ion antiferromagnets. 相似文献
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Using methods for the construction of Lyapunov functions, some Dulac functions are obtained that assure the nonexistence of closed paths for second-order dynamical systems 相似文献
24.
Maria Antònia Barceló Marc Saez Carme Saurina 《The Science of the total environment》2009,407(21):5501-5523
Background
There is evidence that geographic variability of social health inequalities continues to exist even after individual risk factors have been taken into account. However, relatively few studies have examined the contribution of exposure to air pollutants to those inequalities.Objectives
To study the geographic variability of inequalities in mortality and their associations with socioeconomic and environmental inequalities in small areas of the metropolitan of Barcelona during the period 1994 to 2003.Methods
As in the MEDEA Project, the small area unit was the census tract. Study population consisted of the residents of the metropolitan area of Barcelona. Response variables were all-cause and specific-cause standardized mortality ratio (SMR). Explanatory variables were deprivation index, summarizing socioeconomic variables of the census tracts, and estimates of air pollutant exposures. Bayesian hierarchical models were used in order to reduce the extra variability when using SMR and to assess associations between mortality and deprivation and air pollution.Results
Statistically significant associations with deprivation were found for the causes of death related to consumption of tobacco and alcohol for men and, besides lung cancer, diet-related causes for women. Statistically significant pollution coefficients were only found in the metropolitan area of Barcelona and in men. A positive interaction between pollutants and the deprivation index was statistically significant for respiratory mortality and PM10, and ischemic disease mortality and NO2, both for men.Conclusions
We found deprivation to be associated in a statistically significant way with the geographical variation in mortality in the census tracts of the metropolitan area of Barcelona, in the period 1994 to 2003. Those air pollutants more directly related with traffic modify some of these associations. 相似文献25.
Electrochemical treatment of the pollutants generated in an ink-manufacturing process 总被引:1,自引:0,他引:1
Cañizares P Louhichi B Gadri A Nasr B Paz R Rodrigo MA Saez C 《Journal of hazardous materials》2007,146(3):552-557
The effluents of ink-manufacturing processes contain a large variety of pollutants such as dyes, surfactants, biocides, water soluble solvents, etc. In this work, the electrochemical oxidation of several dyes (methylene blue and rhodamine B), solvents (monoethylene glycol, diethylene glycol and glycerol) and surfactants (sodium dodecylbenzenesulfonate) has been studied. To carry out the electrolyses, a bench-scale plant with a single-compartment electrochemical flow-cell was used. Boron doped diamond (BDD) was used as anode and stainless steel (AISI 304) as cathode. For all the compounds tested, the conductive diamond electrooxidation allows achieving the almost complete removal of COD of the waste with a very high current efficiency. The efficiencies of the electrochemical processes seem to depend on the current density and on the nature of the anions contained in the waste (chlorine, sulphate, phosphate). Thus, it has been observed that the use of chloride media favours the treatment of dyes. On the contrary, the use of sulphate- or phosphate-containing solutions improves the removal of the aliphatic compounds studied (solvents). These results suggest an important role of the mediated electrochemical processes on the overall performance of the reaction system. 相似文献
26.
Perez J. Saez de Adana F. Gutierrez O. Gonzalez I. Catedra M.F. Montiel I. Guzman J. 《Antennas and Propagation Magazine, IEEE》1999,41(2):94-98
FASANT is a computer tool for the analysis of antennas on-board satellites, ships, aircraft, and other complex bodies. The structure under analysis, which can be metallic or dielectric (with and/or without losses), must be modeled by plane and/or curved surfaces. The geometrical input files are in DXF format, and can be generated by the most commonly used computer-aided geometrical-design (CAGD) tools. The code can also be applied to the analysis of arrays and arbitrarily shaped reflectors. The kernel of the code is based on the uniform theory of diffraction (UTD). Special algorithms have been developed to speed up the ray-tracing computation for both flat and curved surfaces. FASANT can obtain far-field patterns, field levels at points near the structure, can calculate the mutual coupling between antennas or between array elements, and can show each ray-tracing mechanism 相似文献
27.
Non‐cryptographic hash functions (NCHFs) have an immense number of applications, ranging from compilers and databases to videogames and computer networks. Some of the most important NCHF have been used by major corporations in commercial products. This practical success demonstrates the ability of hashing systems to provide extremely efficient searches over unsorted sets. However, very little research has been devoted to the experimental evaluation of these functions. Therefore, we evaluated the most widely used NCHF using four criteria as follows: collision resistance, distribution of outputs, avalanche effect, and speed. We identified their strengths and weaknesses and found significant flaws in some cases. We also discuss our conclusions regarding general hashing considerations such as selection of the compression map. Our results should assist practitioners and engineers in making more informed choices regarding which function to use for a particular problem. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
28.
Secret sharing schemes with bipartite access structure 总被引:7,自引:0,他引:7
Padro C. Saez G. 《IEEE transactions on information theory / Professional Technical Group on Information Theory》2000,46(7):2596-2604
We study the information rate of secret sharing schemes whose access structure is bipartite. In a bipartite access structure there are two classes of participants and all participants in the same class play an equivalent role in the structure. We characterize completely the bipartite access structures that can be realized by an ideal secret sharing scheme. Both upper and lower bounds on the optimal information rate of bipartite access structures are given. These results are applied to the particular case of weighted threshold access structure with two weights 相似文献
29.
Yessica Saez Laszlo B. Kish Robert Mingesz Zoltan Gingl Claes G. Granqvist 《Journal of Computational Electronics》2014,13(1):271-277
We classify and analyze bit errors in the current measurement mode of the Kirchhoff-law–Johnson-noise (KLJN) key distribution. The error probability decays exponentially with increasing bit exchange period and fixed bandwidth, which is similar to the error probability decay in the voltage measurement mode. We also analyze the combination of voltage and current modes for error removal. In this combination method, the error probability is still an exponential function that decays with the duration of the bit exchange period, but it has superior fidelity to the former schemes. 相似文献
30.