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Search Results: 1 - 10 of 42638 matches for " Rudan Xu "
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An Image Encryption Algorithm Utilizing Julia Sets and Hilbert Curves
Yuanyuan Sun, Lina Chen, Rudan Xu, Ruiqing Kong
PLOS ONE , 2014, DOI: 10.1371/journal.pone.0084655
Abstract: Image encryption is an important and effective technique to protect image security. In this paper, a novel image encryption algorithm combining Julia sets and Hilbert curves is proposed. The algorithm utilizes Julia sets’ parameters to generate a random sequence as the initial keys and gets the final encryption keys by scrambling the initial keys through the Hilbert curve. The final cipher image is obtained by modulo arithmetic and diffuse operation. In this method, it needs only a few parameters for the key generation, which greatly reduces the storage space. Moreover, because of the Julia sets’ properties, such as infiniteness and chaotic characteristics, the keys have high sensitivity even to a tiny perturbation. The experimental results indicate that the algorithm has large key space, good statistical property, high sensitivity for the keys, and effective resistance to the chosen-plaintext attack.
Image Retrieval Based on Fractal Dictionary Parameters
Yuanyuan Sun,Rudan Xu,Lina Chen,Xiaopeng Hu
Mathematical Problems in Engineering , 2013, DOI: 10.1155/2013/689602
Abstract: Content-based image retrieval is a branch of computer vision. It is important for efficient management of a visual database. In most cases, image retrieval is based on image compression. In this paper, we use a fractal dictionary to encode images. Based on this technique, we propose a set of statistical indices for efficient image retrieval. Experimental results on a database of 416 texture images indicate that the proposed method provides a competitive retrieval rate, compared to the existing methods. 1. Introduction With the popularity of the computer and the rapid development of multimedia technology, image information is growing rapidly. How to effectively manage these resources has become a focus of many scholars’ study. The early image retrieval technology is based on text, which relies on manual work that it could hardly meet the users’ needs. Subsequently, a concept of content-based image retrieval (CBIR) is proposed. A new time has come that image management system can analyze image and extract features automatically. Nowadays, CBIR is used in many techniques, including fractal-based image retrieval. Fractal image coding is based on approximating an image by an attractor of a set of affine transformations [3]. To a certain extent, fractal codes reflect spatial relationships between regions, which can describe image content. Sloan [4] first proposed fractal codes based on CBIR. Zhang et al. [5] presented an approach to texture-based image retrieval that determines image similarity on the basis of matching fractal codes. Pi et al. [3] proposed four statistical indices utilizing histograms of range block mean and contrast scaling parameters. Huang et al. [2] used a new statistical method based on kernel density estimation. All of the aforementioned retrieval indices are based on techniques which are similar to traditional fractal coding and are generated by image self-similarity. In this paper, we propose a retrieval method, regarding a shared dictionary as a medium and using the similarity between images and the dictionary as retrieval indices. All the data obtained in the experiments reflect the differences between query image and the dictionary. The remainder of the paper is organized as follows. Section 2 introduces the fractal image coding based on the fractal dictionary. The proposed indices and retrieval method are described in Section 3. Experiment results are reported in Section 4, which is followed by the conclusion. 2. Fractal Image Coding Based On Set Images can be viewed as vectors and can be encoded by a set of transforms. Usually,
A Novel Fractal Coding Method Based on M-J Sets
Yuanyuan Sun, Rudan Xu, Lina Chen, Ruiqing Kong, Xiaopeng Hu
PLOS ONE , 2014, DOI: 10.1371/journal.pone.0101697
Abstract: In this paper, we present a novel fractal coding method with the block classification scheme based on a shared domain block pool. In our method, the domain block pool is called dictionary and is constructed from fractal Julia sets. The image is encoded by searching the best matching domain block with the same BTC (Block Truncation Coding) value in the dictionary. The experimental results show that the scheme is competent both in encoding speed and in reconstruction quality. Particularly for large images, the proposed method can avoid excessive growth of the computational complexity compared with the traditional fractal coding algorithm.
Más allá de la querella benthamista: el gobierno de Ultramaria
Paola Rudan
Araucaria , 2010,
Abstract: El ensayo propone una lectura de la querella benthamista, un choque que duró veinte a os acerca de la cuestión de la ense anza de la ciencia benthamiana del derecho en las universidades colombianas, tendente a superar las contraposiciones habituales entre el benthamismo de Santander y el antibenthamismo de Bolívar. En la primera parte, se examina la difusión de la obra de Bentham en Suramérica, así como su correspondencia directa con ambos líderes independentistas. En la segunda parte, se analizan los discursos políticos y constitucionales de Santander y Bolívar al objeto de indagar la cuestión de la recepción de Bentham en el contexto colombiano, esto es, el modo en el que su doctrina fue usada políticamente transformándose en Benthamismo. Yendo más allá de la querella benthamista se aspira así a mostrar cómo la doctrina benthamiana es desde el principio, incluso para Bolívar, un instrumento fundamental a utilizar en el gobierno de Ultramaria.
Tra i due litiganti: o del segreto successo di Jeremy Bentham in Ultramaria
Paola Rudan
Scienza & Politica : per una Storia delle Dottrine , 2010, DOI: 10.6092/issn.1825-9618/2759
Abstract: Tra i due litiganti: o del segreto successo di Jeremy Bentham in Ultramaria
The Uncomfortable Feminism of a "Political Theorist" Il femminismo scomodo di una "Political Theorist"
Paola Rudan
Scienza & Politica : per una Storia delle Dottrine , 2012, DOI: 10.6092/issn.1825-9618/3200
Abstract: Moving from the publication of the Italian translation of Wendy Brown’s Politics out of History, the essay discusses of two crucial issues for contemporary feminist political theory: the demand for rights and the politics of sexual difference. Concerning the first one, Brown’s peculiar position – her well known critique of rights and her conception of rights as an empty signifier that historically did and still could catalyze powerful political instances – is read through a close understanding of her conception of the relationship between theory and politics. Concerning the second one, it is argued that Brown’s discourse allows to point out the risks implied by the politics of sexual difference both when it does not understand that difference could be a lever for the reproduction of contemporary political power, most of all when “the subject”, however “different”, is conceived as the unavoidable premise of political discourse. A partire dalla pubblicazione della traduzione italiana di La politica fuori dalla storia, di Wendy Brown, il saggio discute due questioni centrali per la teoria politica femminista contemporanea: la rivendicazione di diritti e la politica della differenza sessuale. Rispetto al primo tema, la peculiare posizione di Brown – la sua ben nota critica e la sua concezione dei diritti come significanti vuoti che hanno storicamente e ancora possono catalizzare potenti istanze politiche – è letta attraverso la sua articolazione del rapporto tra teoria e politica; quanto al secondo tema, si suggerisce che il discorso di Brown permetta di sottolineare i rischi impliciti nella politica della differenze sessuale quando essa non si misuri con la capacità del potere contemporaneo di alimentarsi di differenze, e in particolare quando “il soggetto” – per quanto “differente” – continua a essere pensato come presupposto inevitabile del discorso politico.
Syntheses and lyotropic liquid crystal properties of a series of sandwich-type tungstoarsenates heteropoly compounds with As/W ratio of 4/30
Rudan Huang,Lihua Bi,Enbo Wang,Baoli Fei,Lin Xu,Changwen Hu
Chinese Science Bulletin , 1999, DOI: 10.1007/BF02887119
Abstract: A series of sandwich-type tungstoarsenates heteropoly compounds with As/W ratio of 4/30, Na16[As4W30M4(H2O)2O112].XH2O (M = Zn, Cu, Co, Ni, Mn and Cd), have been synthesized for the first time and structurally characterized by elemental analysis, IR and183W NMR spectra. The crystal structure of Na16[As4W30Cu4(H2O)2O112] · 63H2O was determined to be a triclinic system, of P1 symmetry,a = 1.272 l(3) nm,b = 2.451 6(5) nm,c = 2.6.15 0(5) nm, α = 89.90(3)°, β =77.32(3)°, γ = 89.96(3)°,Z = 2. Using tetrahepty lammonium bromide as a phase transfer reagent, [As4W30Cu4(H2O)2O112]16 was transferred from aqueous solution to organic phase (benzene), and the heteropolyanion lost the coordination water molecules to form the coordination-unsaturated ion. After lactic acid was added to the benzene solution, the coordination-saturation was recovered. By esterification reaction between lactic acid and cholesterin, the latter was attached to the heteropolyanion indirectly. Therefore, a new type of lyotropic liquid crystal was obtained, which was characterized by a polarimicroscope, DSC and variable temperature wide-angle X-ray diffraction.
On the Structure and Closure-Conditionof the Hydrodynamic Model
Massimo Rudan,Giorgio Baccarani
VLSI Design , 1995, DOI: 10.1155/1995/42492
Economic Possibilities and Management of Solar Energy Use in Tourism
Economia : Seria Management , 2013,
Abstract: Due to its geographical position and its climate conditions, Croatia as a tourism destination has numerous and completely untapped potentials in solar energy application. Every tourism coastal and island settlement could resolve their key issues in hotels, private accommodation, and other tourism bearers by applying the district heating/cooling systems. Specific condition along the Adriatic Coast should be indicated, with increase in energy security representing an important tourism factor. Authors' research, undertaken among the management of the Kvarner tourism destination, shows only 36% of hotels apply mostly one form of renewable energy source - solar energy, converting it into thermal energy for domestic hot water and heating systems, and seldom use photovoltaic systems for conversion into electric energy. Analysis of survey results of hotel management shows 64% of hotels use no forms of renewable energy sources, nor plan to apply them. The analysis results clearly indicate Croatian numerous benefits and opportunities for significant increase in use of renewable sources, particularly in camping tourism. Its efficacy depends on overcoming both the perceived and well-known barriers, and particularly on weak but in the future indispensable connection of all relevant policies – energy, industrial, agricultural, tourism, environmental protection, construction and areal planning – in order to ensure conditions for sustainable development, with renewable energy sources forming its essential part.
Calculation of Transport Parameters of SiO2 Polymorphs
Elena Gnani,Susanna Reggiani,Renato Colle,Massimo Rudan
VLSI Design , 2001, DOI: 10.1155/2001/64901
Abstract: Silica polymorphs have been analyzed, that are similar to the amorphous phase of SiO2; specifically, the α- and β-quartz, and the α- and β-cristobalite have been addressed. Two different ab initio methods have been used to calculate the full-band structure and the electronic properties of the polymorphs. In particular, the Hartree-Fock (HF) and Density-Functional Theory (DFT) approaches have been selected. A comparison of the energy-band branches and DOS shapes is reported, showing the similarities of the electrical properties that characterize the polymorphs under study. Finally, some relevant properties are compared for the analyzed set of polymorphs.
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