Using classifiers to predict linear feedback shift registers

Proceeding of: IEEE 35th International Carnahan Conference on Security Technology. October 16-19, 2001, LondonPreviously (J.C. Hernandez et al., 2000), some new ideas that justify the use of artificial intelligence techniques in cryptanalysis are presented. The main objective of that paper was to show that the theoretical next bit prediction problem can be transformed into a classification problem, and this classification problem could be solved with the aid of some AI algorithms. In particular, they showed how a well-known classifier called c4.5 could predict the next bit generated by a linear feedback shift register (LFSR, a widely used model of pseudorandom number generator) very efficiently and, most importantly, without any previous knowledge over the model used. The authors look for other classifiers, apart from c4.5, that could be useful in the prediction of LFSRs. We conclude that the selection of c4.5 by Hernandez et al. was adequate, because it shows the best accuracy of all the classifiers tested. However, we have found other classifiers that produce interesting results, and we suggest that these algorithms must be taken into account in the future when trying to predict more complex LFSR-based models. Finally, we show some other properties that make the c4.5 algorithm the best choice for this particular cryptanalytic problem.Publicad

Two fuzziness indexes proposed by Kaufmann: observations about them

Professor Arnold Kaufmann did propose at least two types of indexes for estimating fuzziness in finite standard fuzzy sets. First one has an analogue formulation to that stated by Claude Shannon for measuring uncertainty in a given system. Shannon formulation estimates one type of uncertainty classified as conflict. The present paper will reveal the inconvenience of such an index for measuring fuzziness phenomena. In addition, it is proved algebraic equivalence between another index posed by Kaufmann and a fuzziness index proposed by Ronald Yager.Facultad de Informátic

Análisis, diseño y realización de antenas planas ranuradas multisatélite

A review of designs of linearly polarized parallel-plate slot antennas developed by the authors is presented. Different combinations are described: broadside beam, one and dual tilted-beam, one and dual polarized antennas. The antenna structure, the analysis methods and the feasibility of getting a dual beam and dual linearly polarized antenna with interesting characteristics and low cost are analyzed. Several designs are proposed and their features are studied. As a conclusion, it can be said that parallel- plate slot arrays are quite promising

Synthesis and characterization of polysulfone/layered double hydroxides nanocomposite membranes for fuel cell application

In the present study, sulfonated polysulfone (SPSU)/layered double hydroxide (LDH) composite membranes for use in proton exchange membrane fuel cells (PEMFCs) were investigated. Polysulfone (PSU) was sulfonated with trimethylsilyl chlorosulfonate in 1,2 dichloroethane at room temperature. Composite membranes were prepared by blending different amount (0, 1, 2, and 5%) of LDH nanoparticles with SPSU in dimethylacetamide (DMAc). The membranes were prepared by the casting method and the samples obtained were characterized by XRD, FTIR spectroscopy. The thermal behavior for all samples was evaluated by thermogravimetrical analysis (TGA). Finally electrochemical impedance spectroscopy (EIS) was used to study the membranes electrical properties. The EIS measurements were carried out with the membranes in contact with HCl solutions at different concentrations (103 ≤ c ≤101). Results show a clear dependence of the membrane electrical resistance with the sulfonation degree and the amount of the LDH addedAuthors thanks financial support received from the regional government (Comunidad de Madrid through MATERYENER S2009 PPQ-1626), and Spanish Government,MICINN (MAT2010-19837-CO6)

The histo structure of galls induced by aphids as a useful taxonomic character: the case of rectinasus (Hemiptera, Aphididae, Eriosomatinae)

P. 487-492Morphological differentiation of gall tissues induced on plants may play a role to characterize the real taxonomic position of the gall inducer. We verified this hypothesis with galls induced by Rectinasus buxtoni on Pistacia palaestina. There is controversy about the taxonomic localization of genus Rectinasus: in one classification it is situated with the genera Forda and Paracletus while in another it is linked to the genera Geoica and Baizongia. Histological examination of the walls of the galls reveals the presence of two opposed vascular bundles and an inner surface of the gall with cavities. These features place Rectinasus in the same group as Geoica and Baizongia, and not with Paracletus and Forda, whose galls have a different histological structure, as generally admitted.S

Inclusión de un índice de estimación de incertidumbre, distribución y cohesión de datos en el modelamiento borroso

Este trabajo presenta una propuesta de estimación de la incertidumbre y la calidad de agrupamiento producidos en la identificación de modelos mediante Sistemas de Inferencia Bor r osa del tipo Takagi-Sugeno (SIB TS). Además, propone la integración de tales medidas como criterios evaluador es del modelo con base en la incertidumbre y la partición borrosa generados durante su obtención. Tal estimación hará que el modelo obtenido sea el de menor incremento en la incertidumbre frente a los datos originales del proceso. Además, permite evaluar la distribución y densidad de los datos en los conjuntos bor r osos obtenidos durante el modelamiento usando SIB TS. Los valor es de tal índice pueden ser usados como complemento al modelo final cuando este es usado en cualquier tarea basada en modelo (diseño, optimización, control, etc.). Esas tareas suponen un modelo con incertidumbre uniforme del modelo (que se asume baja), en todo el espacio del modelo. Usando el índice pr opuesto, se puede calcular un valor más realista de la incertidumbre del modelo en cualquier punto del espacio del modelo

Efectos del vibrado del pino piñonero (Pinus pinea L.) en el vigor de los árboles: densidad de copa, crecimiento de guías y parásitos de debilidad

In the Northwest of Spain the mechanized harvesting of pine cones is more and more frequenIn order to quantify the effects of vibration on the vigor of the trees, parcels of stone pine were planted in plateau and countryside. Both the mechanized and manual harvests were analyzed in adult and young trees. The growth of the tree shoots was measured. The presence and abundance of three insect plagues was analyzed in those same trees: Tomicus piniperda, Rhyacionia buoliana and Thaumetopoea pityocampa. The average shoot length of those trees manually harvested was superior to that of those mechanically harvested. The difference was very significant in young trees (40-50 years old) in the countryside and in adult trees (more than 80 years) on the plateau. Rhyacionia buoliana was more abundant in adult trees that young trees, but the relation of its abundance with the harvest method was not seen. The presence of Tomicus piniperda was rare and was only detected in mechanically harvested stands. Thaumetopoea pityocampa was more frequent in trees harvested by hand than those harvested mechanically and was more abundant in young stands. The percentage tree of defoliation was low in all stands independent of harvest method.En el noroeste de España es cada vez más frecuente la recolección mecanizada de piña. Para cuantificar los efectos del vibrado sobre el vigor de los árboles se instalaron en montes de páramo y de campiña parcelas donde se realizó cosecha mecanizada y manual en arbolado adulto y joven. Se midió el crecimiento de los brotes y se analizó la presencia y abundancia de tres insectos plaga sobre estos árboles, Tomicus piniperda y Rhyacionia buoliana, considerados parásitos de debilidad, así como Thaumetopoea pityocampa. La longitud media de los brotes fue superior en árboles cosechados manualmente. La diferencia es importante en árboles jóvenes (40-50 años) de campiñas y en árboles adultos (más de 80 años) de páramos. Rhyacionia buoliana fue más abundante en árboles adultos que en arbolado joven, pero no se vio relación de su abundancia con el método de cosecha. Tomicus piniperda fue escaso y sólo se detectó en rodales cosechados mecanizadamente. Thaumetopoea pityocampa es más frecuente en rodales cosechados manualmente, y en rodales jóvenes lo que indica que selecciona los árboles de crecimiento más vigoroso para alimentarse. Los porcentajes de defoliación fueron bajos en todas las parcelas

Synthesis, structure, and photophysical properties of platinum(II) (N, C, N) pincer complexes derived from purine nucleobases

The synthesis of a series of Pt{κ3-N,C,N′-[L]}X (X = Cl, RC≡C) pincer complexes derived from purine and purine nucleosides is reported. In these complexes, the 6-phenylpurine skeleton provides the N,C-cyclometalated fragment, whereas an amine, imine, or pyridine substituent of the phenyl ring supplies the additional N′-coordination point to the pincer complex. The purine N,C-fragment has two coordination positions with the metal (N1 and N7), but the formation of the platinum complexes is totally regioselective. Coordination through the N7 position leads to the thermodynamically favored [6.5]-Pt{κ3-N7,C,N′-[L]}X complexes. However, the coordination through the N1 position is preferred by the amino derivatives, leading to the isomeric kinetic [5.5]-Pt{κ3-N1,C,N′-[L]}X complexes. Extension of the reported methodology to complexes having both pincer and acetylide ligands derived from nucleosides allows the preparation of novel heteroleptic bis-nucleoside compounds that could be regarded as organometallic models of Pt-induced interstrand cross-link. Complexes having amine or pyridine arms are green phosphorescence emitters upon photoexcitation at low concentrations in CH2Cl2 solution and in poly(methyl methacrylate) (PMMA) films. They undergo self-quenching at high concentrations due to molecular aggregation. The presence of intermolecular π–π stacking and weak Pt···Pt interactions was also observed in the solid state by X-ray diffraction analysis

Vacuum Energy and Renormalization on the Edge

The vacuum dependence on boundary conditions in quantum field theories is analysed from a very general viewpoint. From this perspective the renormalization prescriptions not only imply the renormalization of the couplings of the theory in the bulk but also the appearance of a flow in the space of boundary conditions. For regular boundaries this flow has a large variety of fixed points and no cyclic orbit. The family of fixed points includes Neumann and Dirichlet boundary conditions. In one-dimensional field theories pseudoperiodic and quasiperiodic boundary conditions are also RG fixed points. Under these conditions massless bosonic free field theories are conformally invariant. Among all fixed points only Neumann boundary conditions are infrared stable fixed points. All other conformal invariant boundary conditions become unstable under some relevant perturbations. In finite volumes we analyse the dependence of the vacuum energy along the trajectories of the renormalization group flow providing an interesting framework for dark energy evolution. On the contrary, the renormalization group flow on the boundary does not affect the leading behaviour of the entanglement entropy of the vacuum in one-dimensional conformally invariant bosonic theories.Comment: 10 pages, 1 eps figur

Insertion of isocyanides into zirconium-alkyl bonds of di-ansa-zirconocene complexes. X-ray molecular structure of [Zr{(SiMe2)2(η5-C5H3))Cl(η2-C(i-Pr)N(2,6-Me2C6H3)}]

New dicyclopentadienyl iminoacyl zirconium complexes have been prepared and characterized by NMR spectroscopy. The reaction of [Zr{SiMe2)2(η5-C5H3)2)Me2] with CNR (R  2,6-Me2C6H3, t-Bu) yields [Zr((SiMe2)2(η5-C5H3)2Me(η2-CMeNR)] (R = 2,6-Me2C6H3, t-Bu), which reacts with a stoichiometric amount of water to give the μ-oxo dimers [Zr{(SiMe2)2(η5-C5H3)2}(η2-CMeNR)]2(μ-O) (R = 2,6-Me2C6H3, t-Bu). The chloro neophyl complex [Zr{(SiMe2)2(η5-C5H3)2}Cl(CH2CMe2Ph)] and other β-hydrogen containing zirconium chloro alkyls [Zr{(SiMe2)2(η5-C5H3)2}CIR] (R  Et, n-Pr, i-Pr)_ with CN(2,6-Me2C6H3) to yield the related chloro iminoacyl complexes [Zr{(SiMe2)2(η5-C5H3)2)Cl}η2-CRN(2,6-Me2C6H3)}] (R  Et, n-Pr, i-Pr), whereas no reaction was observed when CN(t-Bu) was used. All the new iminoacyl complexes were characterized by 1H and 13C NMR spectroscopy and the X-ray molecular structure of [Zr{(SiMe2)2(η5-C5H3)2)Cl{η2-C(i-Pr)N(2,6-Me2C6H3)}] studied by diffraction methods to prove the expected ‘inside’ coordination of the iminoacyl nitrogen atom.BID-CONICIT (Venezuela)Comunidad Autónoma de Madri