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Sample records for cm elliptic curves

  1. On the independence of Heegner points associated to distinct quadratic imaginary fields on CM elliptic curves

    CERN Document Server

    Sahinoglu, Hatice

    2011-01-01

    This paper is a complementary to the work Rosen-Silverman, which derives a criteria on the number fields for the independence of Heegner points associated to them on non-CM elliptic curves. This paper shows that the same criteria holds for CM elliptic curves. Generalisation to Heegner points associated to a fixed conductor order of the fields can also be found in this paper.

  2. Formula and 2-adic valuation of L(1) of elliptic curves with CM by -3

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    For the rational integers λ≡1, 3, or 5 (mod 6), considering elliptic curves y2=x3-2433Dλ over the field (-3), the formula for the value at s=1 of Hecke L-series attached to such elliptic curves, expressed as a finite sum of values of Weierstrass -functions, is obtained. Moreover, when λ≡3 (mod 6), the lower bounds of 2-adic valuations of these values are also obtained. These results are consistent with the predictions of the conjecture of Birch and Swinnerton-Dyer in a sense, and have generalized and advanced some results in recent literature.

  3. Special values of L-series attached to two families of CM elliptic curves

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Consider two families of elliptic curves y2 x3 D1 x and y2= x3 4 3 2=x3-D1x and y2=x3-2433D22 over fields ( --1 )and ( -3 ) respectively. Formulae expressed by Weierstrass _qfunctions are given for special values of Hecke L-se ries attached to such elliptic curves. The lower bounds of 2-adic and 3-adic valuations of these values of Hecke L-series as well as criteria for reaching these bounds are obtained. These results are consistent with the predictions of the conjec ture of Birch and Swinnerton-Dyer; and some results in recent literature for more special case and for 2-adic valuation are also developed.

  4. CM elliptic curves and p-adic valuations of their L-series at s=1

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    For rational integers γ and λ, consider two families of (-1) and (-3) respectively. General formulae expressed by Weierstrass -functions are given for special values of Hecke L-series attached to such elliptic curves. The uniform lower bounds of 2-adic and 3-adic valuations of these values of Hecke L-series as well as global criteria for reaching these bounds are obtained. Moreover, when γ=2 and λ=2, 4, further results of 2-adic and 3-adic valuations are obtained for the corresponding curves in more general case of D1 and some restricted D2 respectively. These results are consistent with the predictions of the conjecture of Birch and Swinnerton-Dyer, and greatly develop and generalize some results in recent literature for more special cases.

  5. The Arithmetic of Elliptic Curves

    CERN Document Server

    Silverman, Joseph H

    2009-01-01

    Treats the arithmetic theory of elliptic curves in its modern formulation, through the use of basic algebraic number theory and algebraic geometry. This book discusses the necessary algebro-geometric results, and offers an exposition of the geometry of elliptic curves, and the formal group of an elliptic curve.

  6. Heegner modules and elliptic curves

    CERN Document Server

    Brown, Martin L

    2004-01-01

    Heegner points on both modular curves and elliptic curves over global fields of any characteristic form the topic of this research monograph. The Heegner module of an elliptic curve is an original concept introduced in this text. The computation of the cohomology of the Heegner module is the main technical result and is applied to prove the Tate conjecture for a class of elliptic surfaces over finite fields; this conjecture is equivalent to the Birch and Swinnerton-Dyer conjecture for the corresponding elliptic curves over global fields.

  7. Rational points on elliptic curves

    CERN Document Server

    Silverman, Joseph H

    2015-01-01

    The theory of elliptic curves involves a pleasing blend of algebra, geometry, analysis, and number theory. This book stresses this interplay as it develops the basic theory, thereby providing an opportunity for advanced undergraduates to appreciate the unity of modern mathematics. At the same time, every effort has been made to use only methods and results commonly included in the undergraduate curriculum. This accessibility, the informal writing style, and a wealth of exercises make Rational Points on Elliptic Curves an ideal introduction for students at all levels who are interested in learning about Diophantine equations and arithmetic geometry. Most concretely, an elliptic curve is the set of zeroes of a cubic polynomial in two variables. If the polynomial has rational coefficients, then one can ask for a description of those zeroes whose coordinates are either integers or rational numbers. It is this number theoretic question that is the main subject of this book. Topics covered include the geometry and ...

  8. Amicable pairs and aliquot cycles for elliptic curves

    CERN Document Server

    Stange, Katherine E

    2009-01-01

    An amicable pair for an elliptic curve E/Q is a pair of primes (p,q) of good reduction for E satisfying #E(F_p) = q and #E(F_q) = p. In this paper we study elliptic amicable pairs and analogously defined longer elliptic aliquot cycles. We show that there exist elliptic curves with arbitrarily long aliqout cycles, but that CM elliptic curves (with j not 0) have no aliqout cycles of length greater than two. We give conjectural formulas for the frequency of amicable pairs. For CM curves, the derivation of precise conjectural formulas involves a detailed analysis of the values of the Grossencharacter evaluated at a prime ideal P in End(E) having the property that #E(F_P) is prime. This is especially intricate for the family of curves with j = 0.

  9. Rank of K2 of elliptic curves

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    We prove that (i) rank(K2(E)) 1 for all elliptic curves E defined over Q with a rational torsion point of exact order N 4; (ii) rank(K2(E)) 1 for all but at most one R-isomorphism class of elliptic curves E defined over Q with a rational torsion point of exact order 3. We give some sufficient conditions for rank(K2(EZ)) 1.

  10. Rank of K2 of elliptic curves

    Institute of Scientific and Technical Information of China (English)

    JI QingZhong; QIN HouRong

    2009-01-01

    We prove that (i) rank(K2(E))≥1 for all elliptic curves E defined over Q with a rational torsion point of exact order N≥ 4;(ii) rank(K2(E))≥1 for all but at most one R-isomorphism class of elliptic curves E defined over Q with a rational torsion point of exact order 3.We give some sufficient conditions for rank(K2(Ez))≥1.

  11. EFFICIENT MAPPING METHODS FOR ELLIPTIC CURVE CRYPTOSYSTEMS

    Directory of Open Access Journals (Sweden)

    O.SRINIVASA RAO

    2010-08-01

    Full Text Available The generic name for collection of tools designed to protect data and thwart hackers is Computer Security. The major change that affected security was the introduction of distributed systems and the use of networks and communication facilities for carrying data between terminal user and computer and computer and computer. Network security measures are needed to protect data transmission. Suppose that we had a way of masking the contents of messages or other information traffic so that an attacker, even if he or she captured the message, would be unable to extract the information from the message. The common technique for doing masking is encryption. The encryption is done by using Symmetric key or public key Algorithms. The most commonly used public key algorithms are 1. Rivest Shamir Adelman(RSA and 2 Elliptic Curve cryptography In this paper two different mapping methods of the alphanumeric characters on to the x-y co ordinate of the Elliptic curve defined over a finite field Zp is proposed. The methods are 1 Static (One-to-One Mapping Method and 2 Dynamic (One-to-N Mapping Method. Dynamic mapping method will increase the strength of the Elliptic Cryptosystem. The Results have been attached. The hardness of the elliptic curve discrete logarithm problem (ECDLP is crucial for the security of elliptic curve cryptographic schemes. This report describes the state-of-the-art in mapping the alphanumerical characters on to the x-y coordinates of the elliptic curve points.

  12. Flavor Symmetry and Galois Group of Elliptic Curves

    CERN Document Server

    Hattori, Chuichiro; Matsuoka, Takeo; Nakanishi, Kenichi

    2009-01-01

    A new approach to the generation structure of fermions is proposed. We consider a brane configuration in which the brane intersection yields a two-torus in the extra space. It is assumed that the two-torus is discretized and is given by the torsion points of the elliptic curve over Q . We direct our attention to the arithmetic structure of the elliptic curve with complex multiplication (CM). In our approach the flavor symmetry including the R-parity has its origin in the Galois group of elliptic curves with CM. We study the possible types of the Galois group. The Galois group is shown to be an extension of Z_2 by some abelian group. A phenomenologically viable example of the Galois group is presented, in which the characteristic texture of fermion masses and mixings is reproduced and the mixed-anomaly conditions are satisfied.

  13. Spectral Curves of Operators with Elliptic Coefficients

    Directory of Open Access Journals (Sweden)

    J. Chris Eilbeck

    2007-03-01

    Full Text Available A computer-algebra aided method is carried out, for determining geometric objects associated to differential operators that satisfy the elliptic ansatz. This results in examples of Lamé curves with double reduction and in the explicit reduction of the theta function of a Halphen curve.

  14. Conditionally bounding analytic ranks of elliptic curves

    CERN Document Server

    Bober, Jonathan W

    2011-01-01

    We describe a method for bounding the rank of an elliptic curve under the assumptions of the Birch and Swinnerton-Dyer conjecture and the generalized Riemann hypothesis. As an example, we compute, under these conjectures, exact upper bounds for curves which are known to have rank at least as large as 20, 21, 22, 23, and 24. For the known curve of rank at least 28, we get a bound of 30.

  15. Polynomial Interpolation in the Elliptic Curve Cryptosystem

    Directory of Open Access Journals (Sweden)

    Liew K. Jie

    2011-01-01

    Full Text Available Problem statement: In this research, we incorporate the polynomial interpolation method in the discrete logarithm problem based cryptosystem which is the elliptic curve cryptosystem. Approach: In this study, the polynomial interpolation method to be focused is the Lagrange polynomial interpolation which is the simplest polynomial interpolation method. This method will be incorporated in the encryption algorithm of the elliptic curve ElGamal cryptosystem. Results: The scheme modifies the elliptic curve ElGamal cryptosystem by adding few steps in the encryption algorithm. Two polynomials are constructed based on the encrypted points using Lagrange polynomial interpolation and encrypted for the second time using the proposed encryption method. We believe it is safe from the theoretical side as it still relies on the discrete logarithm problem of the elliptic curve. Conclusion/Recommendations: The modified scheme is expected to be more secure than the existing scheme as it offers double encryption techniques. On top of the existing encryption algorithm, we managed to encrypt one more time using the polynomial interpolation method. We also have provided detail examples based on the described algorithm.

  16. Pseudorandom Bits From Points on Elliptic Curves

    CERN Document Server

    Farashahi, Reza R

    2010-01-01

    Let $\\E$ be an elliptic curve over a finite field $\\F_{q}$ of $q$ elements, with $\\gcd(q,6)=1$, given by an affine Weierstra\\ss\\ equation. We also use $x(P)$ to denote the $x$-component of a point $P = (x(P),y(P))\\in \\E$. We estimate character sums of the form

  17. Elliptic Tales Curves, Counting, and Number Theory

    CERN Document Server

    Ash, Avner

    2012-01-01

    Elliptic Tales describes the latest developments in number theory by looking at one of the most exciting unsolved problems in contemporary mathematics--the Birch and Swinnerton-Dyer Conjecture. The Clay Mathematics Institute is offering a prize of 1 million to anyone who can discover a general solution to the problem. In this book, Avner Ash and Robert Gross guide readers through the mathematics they need to understand this captivating problem. The key to the conjecture lies in elliptic curves, which are cubic equations in two variables. These equations may appear simple, yet they arise from

  18. Classification of Isomonodromy Problems on Elliptic Curves

    CERN Document Server

    Levin, A; Zotov, A

    2013-01-01

    We consider the isomonodromy problems for flat $G$-bundles over punctured elliptic curves $\\Sigma_\\tau$ with regular singularities of connections at marked points. The bundles are classified by their characteristic classes. These classes are elements of the second cohomology group $H^2(\\Sigma_\\tau,{\\mathcal Z}(G))$, where ${\\mathcal Z}(G)$ is the center of $G$. For any complex simple Lie group $G$ and arbitrary class we define the moduli space of flat bundles, and in this way construct the monodromy preserving equations in the Hamiltonian form and their Lax representations. In particular, they include the Painlev\\'e VI equation, its multicomponent generalizations and elliptic Schlesinger equations. The general construction is described for punctured curves of arbitrary genus. We extend the Beilinson-Drinfeld description of the moduli space of Higgs bundles to the case of flat connections. This local description allows us to establish the Symplectic Hecke Correspondence for a wide class of the monodromy preser...

  19. The Selmer Groups of Elliptic Curves

    Institute of Scientific and Technical Information of China (English)

    Fu Zheng WANG

    2003-01-01

    Let E/K be an elliptic curve with K-rational p-torsion points. The p-Selmer group of Eis described by the image of a map λK and hence an upper bound of its order is given in terms of theclass numbers of the S-ideal class group of K and the p-division field of E.

  20. Principal $G$-bundles over elliptic curves

    CERN Document Server

    Friedman, R; Witten, Edward; Friedman, Robert; Morgan, John W.; Witten, Edward

    1997-01-01

    Let $G$ be a simple and simply connected complex Lie group. We discuss the moduli space of holomorphic semistable principal $G$-bundles over an elliptic curve $E$. In particular, we give a new proof of a theorem of Looijenga and Bernshtein-Shvartsman, that the moduli space is a weighted projective space. The method of proof is to study the deformations of certain unstable bundles coming from special maximal parabolic subgroups of $G$. We also discuss the associated automorphism sheaves and universal bundles, as well as the relation between various universal bundles and spectral covers.

  1. Verifiable (t, n) Threshold Signature Scheme Based on Elliptic Curve

    Institute of Scientific and Technical Information of China (English)

    WANG Hua-qun; ZHAO Jun-xi; ZHANG Li-jun

    2005-01-01

    Based on the difficulty of solving the ECDLP (elliptic curve discrete logarithm problem) on the finite field,we present a (t, n) threshold signature scheme and a verifiable key agreement scheme without trusted party. Applying a modified elliptic curve signature equation, we get a more efficient signature scheme than the existing ECDSA (elliptic curve digital signature algorithm) from the computability and security view. Our scheme has a shorter key, faster computation, and better security.

  2. Encryption of Data using Elliptic Curve over Finite fields

    CERN Document Server

    Kumar, D Sravana; Chandrasekhar, A; 10.5121/ijdps.2012.3125

    2012-01-01

    Cryptography is the study of techniques for ensuring the secrecy and authentication of the information. Public-key encryption schemes are secure only if the authenticity of the public-key is assured. Elliptic curve arithmetic can be used to develop a variety of elliptic curve cryptography (ECC) schemes including key exchange, encryption and digital signature. The principal attraction of elliptic curve cryptography compared to RSA is that it offers equal security for a smaller key-size, thereby reducing the processing overhead. In the present paper we propose a new encryption algorithm using some Elliptic Curve over finite fields

  3. Elliptic curves and positive definite ternary forms

    Institute of Scientific and Technical Information of China (English)

    WANG; Xueli(

    2001-01-01

    [1]Pei Dingyi, Rosenberger, G. , Wang Xueli, The eligible numbers of positive definite ternary forms, Math. Zeitschriften,2000, 235: 479-497.[2]Wang Xueli, Pei Dingyi, Modular forms of 3/2 weight and one conjecture of Kaplansky, preprint.[3]Jones, B., The regularity of a genus of positive ternary quadratic forms, Trans. Amer. Math. Soc., 1931, 33: 111-124.[4]Kaplansky, I., The first nontrivial genus of positive definite ternary forms, Math. Comp., 1995, 64: 341-345.[5]Antoniadis, J. A., Bungert, M., Frey, G., Properties of twists of elliptic curves, J. Reine Angew Math., 1990, 405: 1-28.

  4. An algorithm for DLP on anomalous elliptic curves over Fp

    Institute of Scientific and Technical Information of China (English)

    祝跃飞; 裴定一

    2002-01-01

    This paper improves the method of discrete logarithm on anomalous elliptic curves, and establishes an isomorphism from E(Fp) to Fp which can be more easily implemented. Fruthermore, we give an optimized algorithm for discrete logarithm on anomalous elliptic curves E(Fp).

  5. On the average exponent of elliptic curves modulo $p$

    CERN Document Server

    Freiberg, Tristan

    2012-01-01

    Given an elliptic curve $E$ defined over $\\mathbb{Q}$ and a prime $p$ of good reduction, let $\\tilde{E}(\\mathbb{F}_p)$ denote the group of $\\mathbb{F}_p$-points of the reduction of $E$ modulo $p$, and let $e_p$ denote the exponent of said group. Assuming a certain form of the Generalized Riemann Hypothesis (GRH), we study the average of $e_p$ as $p \\le X$ ranges over primes of good reduction, and find that the average exponent essentially equals $p\\cdot c_{E}$, where the constant $c_{E} > 0$ depends on $E$. For $E$ without complex multiplication (CM), $c_{E}$ can be written as a rational number (depending on $E$) times a universal constant. Without assuming GRH, we can determine the average exponent when $E$ has CM, as well as give an upper bound on the average in the non-CM case.

  6. ISOGENOUS OF THE ELLIPTIC CURVES OVER THE RATIONALS

    Institute of Scientific and Technical Information of China (English)

    Abderrahmane Nitaj

    2002-01-01

    An elliptic curve is a pair (E, O), where E is a smooth projective curve of genus 1 and O is a point of E, called the point at infinity. Every elliptic curve can be given by a Weierstrass equationE: y2 + a1xy + a3y = x3 + a2x2 + a4x + a6.Let Q be the set of rationals. E is said to be difined over Q if the coefficients ai, i =1, 2, 3, 4, 6 are rationals and O is defined over Q.Let E/Q be an elliptic curve and let E(Q)tors be the torsion group of points of E defined over Q. The theorem of Mazur asserts that E(Q)tors is one of the following 15 groupsWe say that an elliptic curve E′/Q is isogenous to the elliptic curve E if there is an isogeny,i.e. a morphism φ: E → E′ such that φ(O) = O, where O is the point at infinity.We give an explicit model of all elliptic curves for which E(Q)tors is in the form Z/mZ where m = 9, 10, 12 or Z/2Z × Z/2mZ where m = 4, according to Mazur's theorem.Morever, for every family of such elliptic curves, we give an explicit model of all their isogenous curves with cyclic kernels consisting of rational points.

  7. Cryptanalysis and Improvement of Signcryption Schemes on Elliptic Curves

    Institute of Scientific and Technical Information of China (English)

    LI Xiang-xue; CHEN Ke-fei; LI Shi-qun

    2005-01-01

    In this paper, we analyze two signcryption schemes on elliptic curves proposed by Zheng Yu-liang and Hideki Imai. We point out a serious problem with the schemes that the elliptic curve based signcryption schemes lose confidentiality to gain non-repudiation. We also propose two improvement versions that not only overcome the security leak inherent in the schemes but also provide public verifiability or forward security. Our improvement versions require smaller computing cost than that required by signature-thenencryption methods.

  8. Software Implementation of Elliptic Curve Encryption over Binary Field

    Institute of Scientific and Technical Information of China (English)

    ZHANG Xianfeng; QIN Zhiguang; ZHOU Shijie; LIU Jinde

    2003-01-01

    The mathematical theory for elliptic curve encryption based on optimal normal basis (ONB) over Fm2 is introduced. Then an elliptic curve cryptography(ECC) based encryption scheme is analyzed and designed. The mechanism for key exchange based on Diffie-Hellman is described in details for further applications. Based on these theoretic foundations, the software based on ECC is developed and an application is provided. The software is characterized by excellent security as well as high efficiency.

  9. On algebraically integrable differential operators on an elliptic curve

    CERN Document Server

    Etingof, Pavel

    2010-01-01

    We discuss explicit classification of algebraically integrable (i.e., finite gap) differential operators on elliptic curves with one and several poles. After giving a new exposition of some known results (based on differential Galois theory), we describe a conjectural classification of third order algebraically integrable operators with one pole (obtained using Maple), in particular discovering new "isolated" ones, living on special elliptic curves defined over $\\Bbb Q$. We also discuss algebraically integrable operators with several poles, with and without symmetries, and connect them to elliptic Calogero-Moser systems (in the case with symmetries, to the crystallographic ones, introduced recently by Felder, Ma, Veselov, and the first author).

  10. Implementation of Elliptic Curve Cryptography in Binary Field

    Science.gov (United States)

    Susantio, D. R.; Muchtadi-Alamsyah, I.

    2016-04-01

    Currently, there is a steadily increasing demand of information security, caused by a surge in information flow. There are many ways to create a secure information channel, one of which is to use cryptography. In this paper, we discuss the implementation of elliptic curves over the binary field for cryptography. We use the simplified version of the ECIES (Elliptic Curve Integrated Encryption Scheme). The ECIES encrypts a plaintext by masking the original message using specified points on the curve. The encryption process is done by separating the plaintext into blocks. Each block is then separately encrypted using the encryption scheme.

  11. Zeta Functions for Elliptic Curves I. Counting Bundles

    CERN Document Server

    Weng, Lin

    2012-01-01

    To count bundles on curves, we study zetas of elliptic curves and their zeros. There are two types, i.e., the pure non-abelian zetas defined using moduli spaces of semi-stable bundles, and the group zetas defined for special linear groups. In lower ranks, we show that these two types of zetas coincide and satisfy the Riemann Hypothesis. For general cases, exposed is an intrinsic relation on automorphism groups of semi-stable bundles over elliptic curves, the so-called counting miracle. All this, together with Harder-Narasimhan, Desale-Ramanan and Zagier's result, gives an effective way to count semi-stable bundles on elliptic curves not only in terms of automorphism groups but more essentially in terms of their $h^0$'s. Distributions of zeros of high rank zetas are also discussed.

  12. On some special classes of complex elliptic curves

    CERN Document Server

    Canepa, Bogdan

    2011-01-01

    In this paper we classify the complex elliptic curves $E$ for which there exist cyclic subgroups $C\\leq (E,+)$ of order $n$ such that the elliptic curves $E$ and $E/C$ are isomorphic, where $n$ is a positive integer. Important examples are provided in the last section. Moreover, we answer the following question: given a complex elliptic curve E, when can one find a cyclic subgroup $C$ of order $n$ of $(E,+)$ such that $(E,C)\\sim(\\frac{E}{C},\\frac{E[n]}{C})$, $E[n]$ being the $n$-torsion subgroup of $E$, classifying in this way the fixed points of the action of the Fricke involution on the open modular curves $Y_0(n)$

  13. Binary Sequences from a Pair of Elliptic Curves

    Institute of Scientific and Technical Information of China (English)

    CHEN Zhixiong; ZHANG Ning; XIAO Guozhen

    2006-01-01

    A family of binary sequences were constructed by using an elliptic curve and its twisted curves over finite fields. It was shown that these sequences possess "good" cryptographic properties of 0-1 distribution, long period and large linear complexity. The results indicate that such sequences provide strong potential applications in cryptography.

  14. Eliminating line of sight in elliptic guides using gravitational curving

    DEFF Research Database (Denmark)

    Klenø, Kaspar H.; Willendrup, Peter Kjær; Bergbäck Knudsen, Erik

    2011-01-01

    result in a breakdown of the geometrical focusing mechanism inherent to the elliptical shape, resulting in unwanted reflections and loss of transmission. We present a new and yet untried idea by curving a guide in such a way as to follow the ballistic curve of a neutron in the gravitational field, while...

  15. Advanced topics in the arithmetic of elliptic curves

    CERN Document Server

    Silverman, Joseph H

    1994-01-01

    In the introduction to the first volume of The Arithmetic of Elliptic Curves (Springer-Verlag, 1986), I observed that "the theory of elliptic curves is rich, varied, and amazingly vast," and as a consequence, "many important topics had to be omitted." I included a brief introduction to ten additional topics as an appendix to the first volume, with the tacit understanding that eventually there might be a second volume containing the details. You are now holding that second volume. it turned out that even those ten topics would not fit Unfortunately, into a single book, so I was forced to make some choices. The following material is covered in this book: I. Elliptic and modular functions for the full modular group. II. Elliptic curves with complex multiplication. III. Elliptic surfaces and specialization theorems. IV. Neron models, Kodaira-Neron classification of special fibers, Tate's algorithm, and Ogg's conductor-discriminant formula. V. Tate's theory of q-curves over p-adic fields. VI. Neron's theory of can...

  16. The CM class number one problem for curves

    NARCIS (Netherlands)

    Kilicer, P.

    2016-01-01

    The main subject of this thesis is the CM class number one problem for curves of genus g, in the cases g=2 and g=3. The problem asks for which CM fields of degree 2g with a primitive CM type are the corresponding CM curves of genus g defined over the reflex field. Chapter 1 is an introduction to ab

  17. Steinitz class of elliptic curves with complex multilication

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Let E be any elliptic curve having complex multiplication by the ring CK of integers of the quadratic number field K= Q(- D). Let H be the Hilbert class field of K. The Mordell-Weil group E(H) of H-rational points is a module over the Dedekind domain CK, its structure depends on its Steinitz class. Here the Steinits class is determined when D is any prime number. This result advances the result for the specific elliptic curves when D=10.A general theorem on structure of modules over Dedekind domain is also proposed.

  18. An Elliptic Curve-based Signcryption Scheme with Forward Secrecy

    CERN Document Server

    Toorani, Mohsen; 10.3923/jas.2009.1025.1035

    2010-01-01

    An elliptic curve-based signcryption scheme is introduced in this paper that effectively combines the functionalities of digital signature and encryption, and decreases the computational costs and communication overheads in comparison with the traditional signature-then-encryption schemes. It simultaneously provides the attributes of message confidentiality, authentication, integrity, unforgeability, non-repudiation, public verifiability, and forward secrecy of message confidentiality. Since it is based on elliptic curves and can use any fast and secure symmetric algorithm for encrypting messages, it has great advantages to be used for security establishments in store-and-forward applications and when dealing with resource-constrained devices.

  19. A SECURE PROXY SIGNATURE SCHEME BASED ON ELLIPTIC CURVE CRYPTOSYSTEM

    Institute of Scientific and Technical Information of China (English)

    Hu Bin; Jin Chenhui

    2006-01-01

    Proxy signature is a special digital signature which enables a proxy signer to sign messages on behalf of the original signer. This paper proposes a strongly secure proxy signature scheme and a secure multi-proxy signature scheme based on elliptic curve cryptosystem. Contrast with universal proxy signature schemes, they are secure against key substitute attack even if there is not a certificate authority in the system,and also secure against the original signer's forgery attack. Furthermore, based on the elliptic curve crypto system, they are more efficient and have smaller key size than other system. They can be used in electronics transaction and mobile agent environment.

  20. Galois Lines for Normal Elliptic Space Curves

    Institute of Scientific and Technical Information of China (English)

    Ma. Cristina Lumakin Duyaguit; Hisao Yoshihara

    2005-01-01

    Let C be a curve, and l and lO be lines in the projective three space P3.Consider a projection πl: P3... → lO with center l, where l ∩ lO = 0. Restricting πl to C,we obtain a morphism πl |C: C → lO and an extension of fields (πl|C)*: k(lO) → k(C). If this extension is Galois, then l is said to be a Galois line. We study the defining equations,automorphisms and the Galois lines for quartic curves, and give some applications to the theory ofplane quartic curves.

  1. New digital signature protocol based on elliptic curves

    OpenAIRE

    Abid, Ounasser; Ettanfouhi, Jaouad; Khadir, Omar

    2013-01-01

    In this work, a new digital signature based on elliptic curves is presented. We established its efficiency and security. The method, derived from a variant of ElGamal signature scheme, can be seen as a secure alternative protocol if known systems are completely broken.

  2. Computing endomorphism rings of elliptic curves under the GRH

    CERN Document Server

    Bisson, Gaetan

    2011-01-01

    We design a probabilistic algorithm for computing endomorphism rings of ordinary elliptic curves defined over finite fields that we prove has a subexponential runtime in the size of the base field, assuming solely the generalized Riemann hypothesis. Additionally, we improve the asymptotic complexity of previously known, heuristic, subexponential methods by describing a faster isogeny-computing routine.

  3. On Elliptic Curves Via Heron Triangles and Diophantine Triples

    Directory of Open Access Journals (Sweden)

    F. Izadi

    2014-09-01

    Full Text Available In this article, we construct families of elliptic curves arising from the Heron triangles and Diophantine triples with the Mordell-Weil torsion subgroup of Z/2Z × Z/2Z. These families have ranks at least 2 and 3, respectively, and contain particular examples with rank equal to 7

  4. Singular Fibers in Barking Families of Degenerations of Elliptic Curves

    CERN Document Server

    Okuda, Takayuki

    2012-01-01

    Takamura established a theory on splitting families of degenerations of complex curves. He introduced a powerful method for constructing a splitting family, called a barking family, in which there appear not only a singular fiber over the origin but also singular fibers over other points, called subordinate fibers. In this paper, for the case of degenerations of elliptic curves, we determine the types of these subordinate fibers.

  5. Efficient method for finding square roots for elliptic curves over OEF

    CSIR Research Space (South Africa)

    Abu-Mahfouz, Adnan M

    2009-01-01

    Full Text Available Elliptic curve cryptosystems like others public key encryption schemes, require computing a square roots modulo a prime number. The arithmetic operations in elliptic curve schemes over Optimal Extension Fields (OEF) can be efficiently computed...

  6. A Review on Elliptic Curve Cryptography for Embedded Systems

    CERN Document Server

    Afreen, Rahat

    2011-01-01

    Importance of Elliptic Curves in Cryptography was independently proposed by Neal Koblitz and Victor Miller in 1985.Since then, Elliptic curve cryptography or ECC has evolved as a vast field for public key cryptography (PKC) systems. In PKC system, we use separate keys to encode and decode the data. Since one of the keys is distributed publicly in PKC systems, the strength of security depends on large key size. The mathematical problems of prime factorization and discrete logarithm are previously used in PKC systems. ECC has proved to provide same level of security with relatively small key sizes. The research in the field of ECC is mostly focused on its implementation on application specific systems. Such systems have restricted resources like storage, processing speed and domain specific CPU architecture.

  7. Two-Center Black Holes, Qubits and Elliptic Curves

    CERN Document Server

    Lévay, Péter

    2011-01-01

    We relate the U-duality invariants characterizing two-center extremal black hole solutions in the stu, st^2 and t^3 models of N=2, d=4 supergravity to the basic invariants used to characterize entanglement classes of four-qubit systems. For the elementary example of a D0D4-D2D6 composite in the t^3 model we illustrate how these entanglement invariants are related to some of the physical properties of the two-center solution. Next we show that it is possible to associate elliptic curves to charge configurations of two-center composites. The hyperdeterminant of the hypercube, a four-qubit polynomial invariant of order 24 with 2894276 terms, is featuring the j invariant of the elliptic curve. We present some evidence that this quantity and its straightforward generalization should play an important role in the physics of two-center solutions.

  8. On Lehmer's Conjecture for Polynomials and for Elliptic Curves

    CERN Document Server

    Silverman, Joseph H

    2010-01-01

    A number of authors have proven explicit versions of Lehmer's conjecture for polynomials whose coefficients are all congruent to 1 modulo m. We prove a similar result for polynomials f(X) that are divisible in (Z/mZ)[X] by a polynomial of the form 1+X+...+X^n for some n > \\epsilon*deg(f). We also formulate and prove an analogous statement for elliptic curves.

  9. A Directly Public Verifiable Signcryption Scheme based on Elliptic Curves

    CERN Document Server

    Toorani, Mohsen; 10.1109/ISCC.2009.5202242

    2010-01-01

    A directly public verifiable signcryption scheme is introduced in this paper that provides the security attributes of message confidentiality, authentication, integrity, non-repudiation, unforgeability, and forward secrecy of message confidentiality. It provides the attribute of direct public verifiability so anyone can verify the signcryption without any need for any secret information from the corresponding participants. The proposed scheme is based on elliptic curve cryptography and is so suitable for environments with resource constraints.

  10. ELLIPTIC CURVE CRYPTOGRAPHY BASED AUTHENTICATED KEY AGREEMENT WITH PRE-SHARED PASSWORD

    Institute of Scientific and Technical Information of China (English)

    Sui Aifen; Lucas C.K.Hui; Yang Yixian; K.P.Chow

    2005-01-01

    Based on elliptic curve Diffie-Hellman algorithm, an Elliptic Curve Authenticated Key Agreement (ECAKA) protocol with pre-shared password is proposed. Its security relies on the Elliptic Curve Discrete Logarithm Problem (ECDLP). It provides identity authentication,key validation and perfect forward secrecy, and it can foil man-in-the-middle attacks.

  11. Isomorphism and Generation of Montgomery-Form Elliptic Curves Suitable for Cryptosystems

    Institute of Scientific and Technical Information of China (English)

    LIU Duo; SONG Tao; DAI Yiqi

    2005-01-01

    Many efficient algorithms of Montgomery-form elliptic curve cryptology have been investigated recently. At present, there are no reported studies of the isomorphic class of the Montgomery-form elliptic curve over a finite field. This paper investigates the isomorphism of Montgomery-form elliptic curves via the isomorphism of Weierstrass-form elliptic curves and gives a table of (nearly) all the forms of Montgomery-form elliptic curves suitable for cryptographic usage. Then, an algorithm for generating a secure elliptic curve with Montgomery-form is presented. The most important advantages of the new algorithm are that it avoids the transformation from an elliptic curve's Weierstrass-form to its Montgomery-form, and that it decreases the probability of collision. So, the proposed algorithem is quicker, simpler, and more efficient than the old ones.

  12. Cryptography on elliptic curves over p-adic number fields

    Institute of Scientific and Technical Information of China (English)

    XU MaoZhi; ZHAO ChunLai; FENG Min; REN ZhaoRong; YE JiQing

    2008-01-01

    In this paper we introduce a cryptosystem based on the quotient groups of the group of rational points of an elliptic curve defined over p-adic number field. Some addi-tional parameters are taken in this system, which have an advantage in performing point multiplication while keeping the security of ECC over finite fields. We give a method to select generators of the cryptographic groups, and give a way to represent the elements of the quotient groups with finitely bounded storage by establishing a bijection between these elements and their approximate coordinates. The addition formula under this representation is also presented.

  13. Distribution of some sequences of points on elliptic curves

    DEFF Research Database (Denmark)

    Lange, Tanja; Shparlinski, Igor

    2007-01-01

    We estimate character sums over points on elliptic curves over a finite field of q elements. Pseudorandom sequences can be constructed by taking linear combinations with small coefficients (for example, from the set {−1, 0, 1}) of a fixed vector of points, which forms the seed of the generator. W...... consider several particular cases of this general approach which are of special practical interest and have occurred in the literature. For each of them we show that the resulting sequence has good uniformity of distribution properties....

  14. A Secure Elliptic Curve-Based RFID Protocol

    Institute of Scientific and Technical Information of China (English)

    Santi Martínez; Magda Valls; Concepcó Roig; Josep M. Miret; Francesc Giné

    2009-01-01

    Nowadays, the use of Radio Frequency Identification (RFID) systems in industry and stores has increased.Nevertheless, some of these systems present privacy problems that may discourage potential users. Hence, high confidence and efficient privacy protocols are urgently needed. Previous studies in the literature proposed schemes that are proven to be secure, but they have scalability problems. A feasible and scalable protocol to guarantee privacy is presented in this paper.The proposed protocol uses elliptic curve cryptography combined with a zero knowledge-based authentication scheme. An analysis to prove the system secure, and even forward secure is also provided.

  15. Constructing Pairing-Friendly Elliptic Curves under Embedding Degree 1 for Securing Critical Infrastructures.

    Science.gov (United States)

    Wang, Maocai; Dai, Guangming; Choo, Kim-Kwang Raymond; Jayaraman, Prem Prakash; Ranjan, Rajiv

    2016-01-01

    Information confidentiality is an essential requirement for cyber security in critical infrastructure. Identity-based cryptography, an increasingly popular branch of cryptography, is widely used to protect the information confidentiality in the critical infrastructure sector due to the ability to directly compute the user's public key based on the user's identity. However, computational requirements complicate the practical application of Identity-based cryptography. In order to improve the efficiency of identity-based cryptography, this paper presents an effective method to construct pairing-friendly elliptic curves with low hamming weight 4 under embedding degree 1. Based on the analysis of the Complex Multiplication(CM) method, the soundness of our method to calculate the characteristic of the finite field is proved. And then, three relative algorithms to construct pairing-friendly elliptic curve are put forward. 10 elliptic curves with low hamming weight 4 under 160 bits are presented to demonstrate the utility of our approach. Finally, the evaluation also indicates that it is more efficient to compute Tate pairing with our curves, than that of Bertoni et al.

  16. Constructing Pairing-Friendly Elliptic Curves under Embedding Degree 1 for Securing Critical Infrastructures

    Science.gov (United States)

    Dai, Guangming

    2016-01-01

    Information confidentiality is an essential requirement for cyber security in critical infrastructure. Identity-based cryptography, an increasingly popular branch of cryptography, is widely used to protect the information confidentiality in the critical infrastructure sector due to the ability to directly compute the user’s public key based on the user’s identity. However, computational requirements complicate the practical application of Identity-based cryptography. In order to improve the efficiency of identity-based cryptography, this paper presents an effective method to construct pairing-friendly elliptic curves with low hamming weight 4 under embedding degree 1. Based on the analysis of the Complex Multiplication(CM) method, the soundness of our method to calculate the characteristic of the finite field is proved. And then, three relative algorithms to construct pairing-friendly elliptic curve are put forward. 10 elliptic curves with low hamming weight 4 under 160 bits are presented to demonstrate the utility of our approach. Finally, the evaluation also indicates that it is more efficient to compute Tate pairing with our curves, than that of Bertoni et al. PMID:27564373

  17. Monopoles and Modifications of Bundles over Elliptic Curves

    Directory of Open Access Journals (Sweden)

    Andrey M. Levin

    2009-06-01

    Full Text Available Modifications of bundles over complex curves is an operation that allows one to construct a new bundle from a given one. Modifications can change a topological type of bundle. We describe the topological type in terms of the characteristic classes of the bundle. Being applied to the Higgs bundles modifications establish an equivalence between different classical integrable systems. Following Kapustin and Witten we define the modifications in terms of monopole solutions of the Bogomolny equation. We find the Dirac monopole solution in the case R × (elliptic curve. This solution is a three-dimensional generalization of the Kronecker series. We give two representations for this solution and derive a functional equation for it generalizing the Kronecker results. We use it to define Abelian modifications for bundles of arbitrary rank. We also describe non-Abelian modifications in terms of theta-functions with characteristic.

  18. Constructing elliptic curve isogenies in quantum subexponential time

    CERN Document Server

    Childs, Andrew M; Soukharev, Vladimir

    2010-01-01

    Given two elliptic curves over a finite field having the same cardinality and endomorphism ring, it is known that the curves admit an isogeny between them, but finding such an isogeny is believed to be computationally difficult. The fastest known classical algorithm takes exponential time, and prior to our work no faster quantum algorithm was known. Recently, public-key cryptosystems based on the presumed hardness of this problem have been proposed as candidates for post-quantum cryptography. In this paper, we give a subexponential-time quantum algorithm for constructing isogenies, assuming the Generalized Riemann Hypothesis (but with no other assumptions). This result suggests that isogeny-based cryptosystems may be uncompetitive with more mainstream quantum-resistant cryptosystems such as lattice-based cryptosystems. As part of our algorithm, we also obtain a second result of independent interest: we provide a new subexponential-time classical algorithm for evaluating a horizontal isogeny given its kernel i...

  19. A THRESHOLD BLIND SIGNATURE FROM WEIL PAIRING ON ELLIPTIC CURVES

    Institute of Scientific and Technical Information of China (English)

    Cheng Xiangguo; Xu Weidong; Wang Xinmei

    2006-01-01

    The idea behind a (t, n) threshold blind signature is that a user can ask at least t out ofn players of a group to cooperate to generate a signature for a message without revealing its content. This paper first presents a new blind signature scheme from Weil pairing on elliptic curves. Based on this scheme, a threshold blind signature scheme is proposed. It is efficient and has the security properties of robustness and unforgeability. In the proposed scheme, the group manger is introduced to take the role of distributing the group secret key to each player. However, he cannot forge the players to generate partial blind signatures (Each partial blind signature depends on not only the secret key of the player, but also a random number the player picks). Compared with a threshold signature with a trusted third party, its advantage is obvious; Compared with a threshold signature without a trusted third party, it is more simple and efficient.

  20. String Theory on Elliptic Curve Orientifolds and KR-Theory

    Science.gov (United States)

    Doran, Charles; Méndez-Diez, Stefan; Rosenberg, Jonathan

    2015-04-01

    We analyze the brane content and charges in all of the orientifold string theories on space-times of the form , where E is an elliptic curve with holomorphic or anti-holomorphic involution. Many of these theories involve "twistings" coming from the B-field and/or sign choices on the orientifold planes. A description of these theories from the point of view of algebraic geometry, using the Legendre normal form, naturally divides them into three groupings. The physical theories within each grouping are related to one another via sequences of T-dualities. Our approach agrees with both previous topological calculations of twisted KR-theory and known physics arguments, and explains how the twistings originate from both a mathematical and a physical perspective.

  1. Holomorphic Principal Bundles Over Elliptic Curves III: Singular Curves and Fibrations

    OpenAIRE

    2001-01-01

    Let G be a simple and simply connected complex linear algebraic group. In this paper, we discuss the generalization of the parabolic construction of holomorphic principal G-bundles over a smooth elliptic curve to the case of a singular curve of arithmetic genus one and to a fibration of Weierstrass cubics over a base B. Except for G of type E_8, the method gives a family of weighted projective spaces associated to a sum of line bundles over B. Working with the universal family of Weierstrass ...

  2. On the non-commutative Local Main Conjecture for elliptic curves with complex multiplication

    CERN Document Server

    Venjakob, Otmar

    2012-01-01

    This paper is a natural continuation of the joint work [6] on non-commutative Main Conjectures for CM elliptic curves: now we concentrate on the local Main Conjecture or more precisely on the epsilon-isomorphism conjecture by Fukaya and Kato in [20]. Our results rely heavily on Kato's unpublished proof of (commutative) epsilon-isomorphisms for one dimensional representations of G_{Q_p} in [24]. For the convenience of the reader we give a slight modification or rather reformulation of it in the language of [20] and extend it to the (slightly non-commutative) semi-global setting.

  3. On several families of elliptic curves with arbitrary large Selmer groups

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    In this paper,we calculate the ()-Selmer groups S()(E/Q) and S()(E/Q) of elliptic curves y2 = x(x + εpD)(x + εqD) via the descent method.In particular,we show that the Selmer groups of several families of such elliptic curves can be arbitrary large.

  4. A New Digital Multilevel Proxy Signature Scheme Based on Elliptic Curve Cryptography

    Institute of Scientific and Technical Information of China (English)

    QIN Yanlin; WU Xiaoping

    2006-01-01

    Based on the analysis of elliptic curve digital signature algorithm(ECDSA),aiming at multilevel proxy signature in which the original signer delegates the digital signature authority to several proxies and its security demands, a new multilevel proxy signature scheme based on elliptic curve discrete logarithm problem(ECDLP) is presented and its security are proved.

  5. On the Surjectivity of Galois Representations Associated to Elliptic Curves over Number Fields

    CERN Document Server

    Larson, Eric

    2012-01-01

    Given an elliptic curve $E$ over a number field $K$, the $\\ell$-torsion points $E[\\ell]$ of $E$ define a Galois representation $\\gal(\\bar{K}/K) \\to \\gl_2(\\ff_\\ell)$. A famous theorem of Serre states that as long as $E$ has no Complex Multiplication (CM), the map $\\gal(\\bar{K}/K) \\to \\gl_2(\\ff_\\ell)$ is surjective for all but finitely many $\\ell$. We say that a prime number $\\ell$ is exceptional (relative to the pair $(E,K)$) if this map is not surjective. Here we give a new bound on the largest exceptional prime, as well as on the product of all exceptional primes of $E$. We show in particular that conditionally on the Generalized Riemann Hypothesis (GRH), the largest exceptional prime of an elliptic curve $E$ without CM is no larger than a constant (depending on $K$) times $\\log N_E$, where $N_E$ is the absolute value of the norm of the conductor. This answers affirmatively a question of Serre.

  6. Addition Sequence Method of Scalar Multiplication of Elliptic Curve over OEF

    Institute of Scientific and Technical Information of China (English)

    LIU Duo; DAI Yi-qi

    2005-01-01

    A new elliptic curve scalar multiplication algorithm is proposed. The algorithm uses the Frobenius map on optimal extension field (OEF) and addition sequence. We introduce a new algorithm on generating addition sequence efficiently and also give some analysis about it. Based on this algorithm, a new method of computing scalar multiplication of elliptic curve over an OEF is presented. The new method is more efficient than the traditional scalar multiplication algorithms of elliptic curve over OEF. The comparisons of traditional method and the new method are also given.

  7. TWO FAST ALGORITHMS FOR COMPUTING POINT SCALAR MULTIPLICATIONS ON ELLIPTIC CURVES

    Institute of Scientific and Technical Information of China (English)

    You Lin; Wen Qiaoyan; Xu Maozhi

    2004-01-01

    The key operation in Elliptic Curve Cryptosystems(ECC) is point scalar multiplication. Making use of Frobenius endomorphism, Miiller and Smart proposed two efficient algorithms for point scalar multiplications over even or odd finite fields respectively. This paper reduces thementation of our Algorithm 1 in Maple for a given elliptic curve shows that it is at least as twice fast as binary method. By setting up a precomputation table, Algorithm 2, an improved version of Algorithm 1, is proposed. Since the time for the precomputation table can be considered free,Algorithm 2 is about (3/2) log2 q - 1 times faster than binary method for an elliptic curve over Fq.

  8. A blind digital signature scheme using elliptic curve digital signature algorithm

    OpenAIRE

    BÜTÜN, İsmail; DEMİRER, Mehmet

    2013-01-01

    In this study, we propose a blind digital signature (BDS) scheme based on the elliptic curve digital signature algorithm that increases the performance significantly. The security of our scheme is based on the difficulty of the elliptic curve discrete algorithm problem. Therefore, it offers much smaller key lengths for the desired security levels, along with much faster cryptographic processes, leading to fewer hardware and software requirements. According to our simulation results, ...

  9. A Heuristic Method of Scalar Multiplication of Elliptic Curve over OEF

    Institute of Scientific and Technical Information of China (English)

    LIU Duo; LUO Ping; DAI Yi-qi

    2006-01-01

    Elliptic curve cryptosystem is the focus of public key cryptology nowadays, for it has many advantages RSA lacks. This paper introduced a new heuristic algorithm on computing multiple scalar multiplications of a given point. Based on this algorithm, a new method of computing scalar multiplication of elliptic curve over optimal extension field (OEF) using Frobenius map was presented. The new method is more efficient than the traditional ones. In the last part of this paper, the comparison was given in the end.

  10. Elliptic Curve Cryptography with Security System in Wireless Sensor Networks

    Science.gov (United States)

    Huang, Xu; Sharma, Dharmendra

    2010-10-01

    The rapid progress of wireless communications and embedded micro-electro-system technologies has made wireless sensor networks (WSN) very popular and even become part of our daily life. WSNs design are generally application driven, namely a particular application's requirements will determine how the network behaves. However, the natures of WSN have attracted increasing attention in recent years due to its linear scalability, a small software footprint, low hardware implementation cost, low bandwidth requirement, and high device performance. It is noted that today's software applications are mainly characterized by their component-based structures which are usually heterogeneous and distributed, including the WSNs. But WSNs typically need to configure themselves automatically and support as hoc routing. Agent technology provides a method for handling increasing software complexity and supporting rapid and accurate decision making. This paper based on our previous works [1, 2], three contributions have made, namely (a) fuzzy controller for dynamic slide window size to improve the performance of running ECC (b) first presented a hidden generation point for protection from man-in-the middle attack and (c) we first investigates multi-agent applying for key exchange together. Security systems have been drawing great attentions as cryptographic algorithms have gained popularity due to the natures that make them suitable for use in constrained environment such as mobile sensor information applications, where computing resources and power availability are limited. Elliptic curve cryptography (ECC) is one of high potential candidates for WSNs, which requires less computational power, communication bandwidth, and memory in comparison with other cryptosystem. For saving pre-computing storages recently there is a trend for the sensor networks that the sensor group leaders rather than sensors communicate to the end database, which highlighted the needs to prevent from the man

  11. Seiberg-Witten curves and double-elliptic integrable systems

    CERN Document Server

    Aminov, G; Mironov, A; Morozov, A; Zotov, A

    2014-01-01

    An old conjecture claims that commuting Hamiltonians of the double-elliptic integrable system are constructed from the theta-functions associated with Riemann surfaces from the Seiberg-Witten family, with moduli treated as dynamical variables and the Seiberg-Witten differential providing the pre-symplectic structure. We describe a number of theta-constant equations needed to prove this conjecture for the $N$-particle system. These equations provide an alternative method to derive the Seiberg-Witten prepotential and we illustrate this by calculating the perturbative contribution. We provide evidence that the solutions to the commutativity equations are exhausted by the double-elliptic system and its degenerations (Calogero and Ruijsenaars systems). Further, the theta-function identities that lie behind the Poisson commutativity of the three-particle Hamiltonians are proven.

  12. Seiberg-Witten curves and double-elliptic integrable systems

    Science.gov (United States)

    Aminov, G.; Braden, H. W.; Mironov, A.; Morozov, A.; Zotov, A.

    2015-01-01

    An old conjecture claims that commuting Hamiltonians of the double-elliptic integrable system are constructed from the theta-functions associated with Riemann surfaces from the Seiberg-Witten family, with moduli treated as dynamical variables and the Seiberg-Witten differential providing the pre-symplectic structure. We describe a number of theta-constant equations needed to prove this conjecture for the N-particle system. These equations provide an alternative method to derive the Seiberg-Witten prepotential and we illustrate this by calculating the perturbative contribution. We provide evidence that the solutions to the commutativity equations are exhausted by the double-elliptic system and its degenerations (Calogero and Ruijsenaars systems). Further, the theta-function identities that lie behind the Poisson commutativity of the three-particle Hamiltonians are proven.

  13. Collisions in Fast Generation of Ideal Classes and Points on Hyperelliptic and Elliptic Curves

    DEFF Research Database (Denmark)

    Lange, Tanja; Shparlinski, Igor

    2005-01-01

    Koblitz curves have been proposed to quickly generate random ideal classes and points on hyperelliptic and elliptic curves. To obtain a further speed-up a different way of generating these random elements has recently been proposed. In this paper we give an upper bound on the number of collisions...

  14. FPGA Based High Speed SPA Resistant Elliptic Curve Scalar Multiplier Architecture

    Directory of Open Access Journals (Sweden)

    Khalid Javeed

    2016-01-01

    Full Text Available The higher computational complexity of an elliptic curve scalar point multiplication operation limits its implementation on general purpose processors. Dedicated hardware architectures are essential to reduce the computational time, which results in a substantial increase in the performance of associated cryptographic protocols. This paper presents a unified architecture to compute modular addition, subtraction, and multiplication operations over a finite field of large prime characteristic GF(p. Subsequently, dual instances of the unified architecture are utilized in the design of high speed elliptic curve scalar multiplier architecture. The proposed architecture is synthesized and implemented on several different Xilinx FPGA platforms for different field sizes. The proposed design computes a 192-bit elliptic curve scalar multiplication in 2.3 ms on Virtex-4 FPGA platform. It is 34% faster and requires 40% fewer clock cycles for elliptic curve scalar multiplication and consumes considerable fewer FPGA slices as compared to the other existing designs. The proposed design is also resistant to the timing and simple power analysis (SPA attacks; therefore it is a good choice in the construction of fast and secure elliptic curve based cryptographic protocols.

  15. The Ising model: from elliptic curves to modular forms and Calabi-Yau equations

    Energy Technology Data Exchange (ETDEWEB)

    Bostan, A [INRIA Paris-Rocquencourt, Domaine de Voluceau, B.P. 105 78153 Le Chesnay Cedex (France); Boukraa, S [LPTHIRM and Departement d' Aeronautique, Universite de Blida, Blida (Algeria); Hassani, S; Zenine, N [Centre de Recherche Nucleaire d' Alger, 2 Bd. Frantz Fanon, BP 399, 16000 Alger (Algeria); Van Hoeij, M [Florida State University, Department of Mathematics, 1017 Academic Way, Tallahassee, FL 32306-4510 (United States); Maillard, J-M [LPTMC, UMR 7600 CNRS, Universite de Paris, Tour 23, 5eme etage, Case 121, 4 Place Jussieu, 75252 Paris Cedex 05 (France); Weil, J-A, E-mail: alin.bostan@inria.fr, E-mail: boukraa@mail.univ-blida.dz, E-mail: hoeij@mail.math.fsu.edu, E-mail: maillard@lptmc.jussieu.fr, E-mail: jacques-arthur.weil@unilim.fr, E-mail: njzenine@yahoo.com [XLIM, Universite de Limoges, 123 Avenue Albert Thomas, 87060 Limoges Cedex (France)

    2011-01-28

    We show that almost all the linear differential operators factors obtained in the analysis of the n-particle contributions of the susceptibility of the Ising model for n {<=} 6 are linear differential operators associated with elliptic curves. Beyond the simplest differential operators factors which are homomorphic to symmetric powers of the second order operator associated with the complete elliptic integral E, the second and third order differential operators Z{sub 2}, F{sub 2}, F{sub 3}, L-tilde {sub 3} can actually be interpreted as modular forms of the elliptic curve of the Ising model. A last order-4 globally nilpotent linear differential operator is not reducible to this elliptic curve, modular form scheme. This operator is shown to actually correspond to a natural generalization of this elliptic curve, modular form scheme, with the emergence of a Calabi-Yau equation, corresponding to a selected {sub 4}F{sub 3} hypergeometric function. This hypergeometric function can also be seen as a Hadamard product of the complete elliptic integral K, with a remarkably simple algebraic pull-back (square root extension), the corresponding Calabi-Yau fourth order differential operator having a symplectic differential Galois group SP(4,C). The mirror maps and higher order Schwarzian ODEs, associated with this Calabi-Yau ODE, present all the nice physical and mathematical ingredients we had with elliptic curves and modular forms, in particular an exact (isogenies) representation of the generators of the renormalization group, extending the modular group SL(2,Z) to a GL(2,Z) symmetry group.

  16. The history of the universe is an elliptic curve

    CERN Document Server

    Coquereaux, Robert

    2014-01-01

    Friedmann-Lemaitre equations with contributions coming from matter, curvature, cosmological constant, and radiation, when written in terms of conformal time u rather than in terms of cosmic time t, can be solved explicitly in terms of standard Weierstrass elliptic functions. The spatial scale factor, the temperature, the densities, the Hubble function, and almost all quantities of cosmological interest (with the exception of t itself) are elliptic functions of u, in particular they are bi-periodic with respect to a lattice of the complex plane, when one takes u complex. After recalling the basics of the theory, we use these explicit expressions, as well as the experimental constraints on the present values of density parameters (we choose for the curvature density a small value in agreement with experimental bounds) to display the evolution of the main cosmological quantities for one real period 2 omega_r of conformal time (the cosmic time t never end but it goes to infinity for a finite value u_f < 2 omeg...

  17. A Fair E-Cash Scheme Based on Elliptic Curve Cryptography

    Institute of Scientific and Technical Information of China (English)

    WANG Changji; WU Jianping; DUAN Haixin

    2004-01-01

    A new fair off-line electronic cash scheme on elliptic curve cryptography was presented. The new scheme is more efficient than those by extending fair off-line electronic cash scheme from finite field into elliptic curve cryptography and introducing a new elliptic curve discrete logarithm assumption. The expiry date and denomination are embedded into the blindly signed coin by integrating partially blind signature with restrictive blind signature. A bank need not use different public keys for different coin values, shops and users need not carry a list of bank's public keys to verify in their electronic wallet. At the same time, the bank just needs to keep undue electronic coins for double spending check in his database, thus bank's database can be dramatically reduced.

  18. Elliptic Curves of Twin-Primes Over Gauss Field and Diophantine Equations

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    @@  Let p, q be twin prime numbers with q-p=2 . Consider the elliptic curves E=E :   y2 = x (x+σp)(x+σq).  (σ=1)  (1) E=Eσ is also denoted as E+ or E- when =+1 or -1.Here the Mordell-Weil group and the rank of the elliptic curve Eover the Gaussfield K=Q(2-1) (and over the rationalfield Q) will be determined in several cases; andresults of solutions forrelated Diophantine equations and simultaneous Pellianequations will be given. The arithmetic constructsover Q of the elliptic curve E have been studiedin [1], the Selmer groups are determined, results on Mordell- Weil group, rank, Shafarevich-Tate group, and torsion subgroups are also obtained. Results on torsion subgroups in [2] will be used here to determine E(K).

  19. The difference between the Weil height and the canonical height on elliptic curves

    Science.gov (United States)

    Silverman, Joseph H.

    1990-10-01

    Estimates for the difference of the Weil height and the canonical height of points on elliptic curves are used for many purposes, both theoretical and computational. In this note we give an explicit estimate for this difference in terms of the j-invariant and discriminant of the elliptic curve. The method of proof, suggested by Serge Lang, is to use the decomposition of the canonical height into a sum of local heights. We illustrate one use for our estimate by computing generators for the Mordell-Weil group in three examples.

  20. Digital Multi-Signature Scheme Based on the Elliptic Curve Cryptosystem

    Institute of Scientific and Technical Information of China (English)

    Tzer-Shyong Chen; Kuo-Hsuan Huang; Yu-Fang Chung

    2004-01-01

    In the study,the digital multi-signature scheme,constructed by the integration of one-way hash function and identification scheme,are proposed based on the elliptic curve cryptosystem(ECC).To the efficiency in performance,the ECC has been generally regarded as positive; and the security caused by the Elliptic Curve Discrete Logarithm Problem(ECDLP)is highly also taken highly important.The main characteristic of the proposed scheme is that the length of the multi-signature is fixed rather than changeable and it will not increase with the number of group members.

  1. Solving the Multi-discrete Logarithm Problems over a Group of Elliptic Curves with Prime Order

    Institute of Scientific and Technical Information of China (English)

    Jun Quan LI; Mu Lan LIU; Liang Liang XIAO

    2005-01-01

    In this paper, we discuss the expected number of steps in solving multi-discrete logarithm problems over a group of elliptic curves with prime order by using Pollard's rho method and parallel collision search algorithm. We prove that when using these algorithms to compute discrete logarithms,the knowledge gained through computing many logarithms does not make it easier for finding other logarithms. Hence in an elliptic cryptosystem, it is safe for many users to share the same curve, with different private keys.

  2. Curve counting on elliptically fibered Calabi-Yau 3-folds

    CERN Document Server

    Oberdieck, Georg

    2016-01-01

    Let $X$ be a Calabi-Yau threefold and let $X \\to S$ be an elliptic fibration with integral fibers. We use a derived autoequivalence and wall-crossing to prove a functional equation for the generating series of Pandharipande-Thomas invariants of $X$ over reduced classes in the base. The generating series is expressed as Noether-Lefschetz terms (counting sections and conjectured to be modular forms) times universal Jacobi forms coming from the fiber geometry. Parallel results are proven for the topological Euler characteristic of the moduli spaces. We exhibit applications and compare to known results for the Schoen Calabi-Yau, the product $\\mathrm{K3} \\times E$ and for abelian threefolds. We prove that the generating series of Pandharipande-Thomas invariants for $\\mathrm{K3} \\times E$ with respect to a primitive class on the $\\mathrm{K3}$ is a quasi-Jacobi form. We also discuss the relationship to the Noether-Lefschetz theory of K3 fibered Calabi-Yau threefolds in the case of the STU-model.

  3. Broken bracelets, Molien series, paraffin wax and an elliptic curve of conductor 48

    CERN Document Server

    Amdeberhan, Tewodros; Moll, Victor H

    2011-01-01

    This paper introduces the concept of necklace binomial coefficients motivated by the enumeration of a special type of sequences. Several properties of these coefficients are described, including a connection between their roots and an elliptic curve. Further links are given to a physical model from quantum mechanical supersymmetry as well as properties of alkane molecules in chemistry.

  4. Elliptic Curves of High Rank with Nontrivial Torsion Group over $\\Q$

    OpenAIRE

    2001-01-01

    We construct elliptic curves over $\\Q$ of high Mordell--Weil rank, with a nontrivial torsion subgroup. We improve the rank records for the cases $\\Z/2\\Z \\times \\Z/2\\Z$, $\\Z/3\\Z$, $\\Z/4\\Z$, $\\Z/5\\Z$, $\\Z/6\\Z$, $\\Z/7\\Z$ and $\\Z/8\\Z$.

  5. A key distribution scheme using elliptic curve cryptography in wireless sensor networks

    CSIR Research Space (South Africa)

    Louw, J

    2016-12-01

    Full Text Available Conference on Industrial Informatics (INDIN), 19-21 July 2016, Futuroscope-Poitiers, France A key distribution scheme using elliptic curve cryptography in wireless sensor networks J. Louw ; G. Niezen ; T. D. Ramotsoela ; A. M. Abu-Mahfouz Abstract...

  6. Integrated x-ray reflectivity measurements of elliptically curved pentaerythritol crystals

    Energy Technology Data Exchange (ETDEWEB)

    Haugh, M. J.; Jacoby, K. D.; Ross, P. W. [National Security Technologies, LLC, Livermore, California 94551 (United States); Regan, S. P.; Magoon, J.; Shoup, M. J. III [Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14623 (United States); Barrios, M. A.; Emig, J. A.; Fournier, K. B. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States)

    2012-10-15

    The elliptically curved pentaerythritol (PET) crystals used in the Supersnout 2 x-ray spectrometer on the National Ignition Facility at Lawrence Livermore National Laboratory have been calibrated photometrically in the range of 5.5-16 keV. The elliptical geometry provides broad spectral coverage and minimizes the degradation of spectral resolution due to the finite source size. The reflectivity curve of the crystals was measured using a x-ray line source. The integrated reflectivity (R{sub I}) and width of its curve ({Delta}{Theta}) were the measurements of major interest. The former gives the spectrometer throughput, and the latter gives the spectrometer resolving power. Both parameters are found to vary considerably with the radius of curvature of the crystal and with spectral energy. The results are attributed to an enhanced mosaic effect due to the increase in curvature. There are also contributions from the crystal cleaving and gluing processes.

  7. Fourier-Mukai and Nahm transforms for holomorphic triples on elliptic curves

    Science.gov (United States)

    García-Prada, Oscar; Hernández Ruipérez, Daniel; Pioli, Fabio; Tejero Prieto, Carlos

    2005-12-01

    We define a Fourier-Mukai transform for a triple consisting of two holomorphic vector bundles over an elliptic curve and a homomorphism between them. We prove that in some cases, the transform preserves the natural stability condition for a triple. We also define a Nahm transform for solutions to natural gauge-theoretic equations on a triple—vortices—and explore some of its basic properties. Our approach combines direct methods with dimensional reduction techniques, relating triples over a curve with vector bundles over the product of the curve with the complex projective line.

  8. An Interoperability Consideration in Selecting Domain Parameters for Elliptic Curve Cryptography

    Science.gov (United States)

    Ivancic, Will (Technical Monitor); Eddy, Wesley M.

    2005-01-01

    Elliptic curve cryptography (ECC) will be an important technology for electronic privacy and authentication in the near future. There are many published specifications for elliptic curve cryptosystems, most of which contain detailed descriptions of the process for the selection of domain parameters. Selecting strong domain parameters ensures that the cryptosystem is robust to attacks. Due to a limitation in several published algorithms for doubling points on elliptic curves, some ECC implementations may produce incorrect, inconsistent, and incompatible results if domain parameters are not carefully chosen under a criterion that we describe. Few documents specify the addition or doubling of points in such a manner as to avoid this problematic situation. The safety criterion we present is not listed in any ECC specification we are aware of, although several other guidelines for domain selection are discussed in the literature. We provide a simple example of how a set of domain parameters not meeting this criterion can produce catastrophic results, and outline a simple means of testing curve parameters for interoperable safety over doubling.

  9. On the high rank $\\pi/3$ and $2\\pi/3$-congruent number elliptic curves

    CERN Document Server

    Janfada, A S

    2011-01-01

    In this article, we try to find high rank elliptic curves in the family $E_{n,\\theta}$ defined over $\\mathbb Q$ by the equation $y^2=x^3+2snx-(r^2-s^2)n^2x$, where $0 < \\theta < \\pi$, $\\cos(\\theta) = s/r$ is rational with $0\\leq |s| elliptic curves are related to the $\\theta$-congruent number problem as a generalization of the classical congruent number problem. We consider two special cases $\\theta=\\pi/3$ and $\\theta=2\\pi/3$. Then by searching in a certain known family of $\\theta$-congruent numbers and using Mestre-Nagao sum as a sieving tool, we find some square free integers $n$ such that $E_{n, \\theta}(\\mathbb Q)$ has Mordell-Weil rank up to 7 in the first case and 6 in the second case.

  10. On θ-Congruent Numbers, Rational Squares in Arithmetic Progressions, Concordant Forms and Elliptic Curves

    Directory of Open Access Journals (Sweden)

    Erich Selder

    2015-01-01

    Full Text Available The correspondence between right triangles with rational sides, triplets of rational squares in arithmetic succession and integral solutions of certain quadratic forms is well-known. We show how this correspondence can be extended to the generalized notions of rational θ-triangles, rational squares occurring in arithmetic progressions and concordant forms. In our approach we establish one-to-one mappings to rational points on certain elliptic curves and examine in detail the role of solutions of the θ-congruent number problem and the concordant form problem associated with nontrivial torsion points on the corresponding elliptic curves. This approach allows us to combine and extend some disjoint results obtained by a number of authors, to clarify some statements in the literature and to answer some hitherto open questions.

  11. A Novel Elliptic curve cryptography Processor using NoC design

    CERN Document Server

    Javashi, Hamid

    2011-01-01

    In this paper, we propose an elliptic curve key generation processor over GF(2m) and GF(P) with Network-on-Chip (NoC) design scheme based on binary scalar multiplication algorithm. Over the Two last decades, Elliptic Curve Cryptography (ECC) has gained increasing acceptance in the industry and the academic community. This interest is mainly caused by the same level of security with relatively small keys provided by ECC comparing to large key size in Rivest Shamir Adleman (RSA). Parallelism can be utilized in different hierarchy levels as shown in many publications. By using NoC, a new method with the reduced latency of point multiplication (with parallel field arithmetic) is introduced in this paper.

  12. High-performance hardware architecture of elliptic curve cryptography processor over GF(2163)

    Institute of Scientific and Technical Information of China (English)

    Yong-ping DAN; Xue-cheng ZOU; Zheng-lin LIU; Yu HAN; Li-hua YI

    2009-01-01

    We propose a novel high-performance hardware architecture of processor for elliptic curve scalar multiplication based on the Lopez-Dahab algorithm over GF(2163) in polynomial basis representation. The processor can do all the operations using an efficient modular arithmetic logic unit, which includes an addition unit, a square and a carefully designed multiplication unit. In the proposed architecture, multiplication, addition, and square can be performed in parallel by the decomposition of computation. The point addition and point doubling iteration operations can be performed in six multiplications by optimization and solution of data dependency. The implementation results based on Xilinx Virtexll XC2V6000 FPGA show that the proposed design can do random elliptic curve scalar multiplication GF(2163) in 34.11 μs, occupying 2821 registers and 13 376 LUTs.

  13. Design of highly efficient elliptic curve crypto-processor with two multiplications over GF(2163)

    Institute of Scientific and Technical Information of China (English)

    DAN Yong-ping; ZOU Xue-cheng; LIU Zheng-lin; HAN Yu; YI Li-hua

    2009-01-01

    In this article, a parallel hardware processor is presented to compute elliptic curve scalar multiplication in polynomial basis representation. The processor is applicable to the operations of scalar multiplication by using a modular arithmetic logic unit (MALU). The MALU consists of two multiplications, one addition, and one squaring. The two multiplications and the addition or squaring can be computed in parallel. The whole computations of scalar multiplication over GF(2163) can be performed in 3 064 cycles. The simulation results based on Xilinx Virtex2 XC2V6000 FPGAs show that the proposed design can compute random GF(2163) elliptic curve scalar multiplication operations in 31.17 μs, and the resource occupies 3 994 registers and 15 527 LUTs, which indicates that the crypto-processor is suitable for high-performance application.

  14. Implementation of diffie-Hellman key exchange on wireless sensor using elliptic curve cryptography

    DEFF Research Database (Denmark)

    Khajuria, Samant; Tange, Henrik

    2009-01-01

    This work describes a low-cost public key cryptography (PKC) based solution for security services such as authentication as required for wireless sensor networks. We have implemented a software approach using elliptic curve cryptography (ECC) over GF (2m) in order to obtain stronger cryptography....... from Crossbow. Results has shown that the point calculation can be done fairly amount of time with relatively small space consumption......This work describes a low-cost public key cryptography (PKC) based solution for security services such as authentication as required for wireless sensor networks. We have implemented a software approach using elliptic curve cryptography (ECC) over GF (2m) in order to obtain stronger cryptography...

  15. Computation of ATR Darmon points on non-geometrically modular elliptic curves

    CERN Document Server

    Guitart, Xavier

    2012-01-01

    ATR points were introduced by Darmon as a conjectural construction of algebraic points on certain elliptic curves for which in general the Heegner point method is not available. So far the only numerical evidence, provided by Darmon--Logan and G\\"artner, concerned curves arising as quotients of Shimura curves. In those special cases the ATR points can be obtained from the already existing Heegner points, thanks to results of Zhang and Darmon--Rotger--Zhao. In this paper we compute for the first time an algebraic ATR point on a curve which is not uniformizable by any Shimura curve, thus providing the first piece of numerical evidence that Darmon's construction works beyond geometric modularity. To this purpose we improve the method proposed by Darmon and Logan by removing the requirement that the real quadratic field be norm-euclidean, and accelerating the numerical integration of Hilbert modular forms.

  16. Monodromy of a Class of Logarithmic Connections on an Elliptic Curve

    Directory of Open Access Journals (Sweden)

    Francois-Xavier Machu

    2007-08-01

    Full Text Available The logarithmic connections studied in the paper are direct images of regular connections on line bundles over genus-2 double covers of the elliptic curve. We give an explicit parametrization of all such connections, determine their monodromy, differential Galois group and the underlying rank-2 vector bundle. The latter is described in terms of elementary transforms. The question of its (semi-stability is addressed.

  17. An Elliptic Curve Cryptography-Based RFID Authentication Securing E-Health System

    OpenAIRE

    2015-01-01

    Mobile healthcare (M-health) systems can monitor the patients’ conditions remotely and provide the patients and doctors with access to electronic medical records, and Radio Frequency Identification (RFID) technology plays an important role in M-health services. It is important to securely access RFID data in M-health systems: here, authentication, privacy, anonymity, and tracking resistance are desirable security properties. In 2014, He et al. proposed an elliptic curve cryptography- (ECC-) b...

  18. Sums of two biquadrate and elliptic curves of rank $\\geq 4$

    CERN Document Server

    Izadi, F A; Nabardi, K

    2012-01-01

    Let $n$ be an odd number which can be written in two different ways as sums of two biquadrate. Then we show that the elliptic curves $y^2=x^3-nx$ have rank$\\geq 4$. If $n$ is even number with the same property, then the rank$\\geq 3$. Moreover, some examples of ranks equal to 4, 5, 6, 7, and 8 are given.

  19. Design of an Elliptic Curve Cryptography Processor for RFID Tag Chips

    Directory of Open Access Journals (Sweden)

    Zilong Liu

    2014-09-01

    Full Text Available Radio Frequency Identification (RFID is an important technique for wireless sensor networks and the Internet of Things. Recently, considerable research has been performed in the combination of public key cryptography and RFID. In this paper, an efficient architecture of Elliptic Curve Cryptography (ECC Processor for RFID tag chip is presented. We adopt a new inversion algorithm which requires fewer registers to store variables than the traditional schemes. A new method for coordinate swapping is proposed, which can reduce the complexity of the controller and shorten the time of iterative calculation effectively. A modified circular shift register architecture is presented in this paper, which is an effective way to reduce the area of register files. Clock gating and asynchronous counter are exploited to reduce the power consumption. The simulation and synthesis results show that the time needed for one elliptic curve scalar point multiplication over GF(2163 is 176.7 K clock cycles and the gate area is 13.8 K with UMC 0.13 μm Complementary Metal Oxide Semiconductor (CMOS technology. Moreover, the low power and low cost consumption make the Elliptic Curve Cryptography Processor (ECP a prospective candidate for application in the RFID tag chip.

  20. Efficient Implementation of Elliptic Curve Cryptography Using Low-power Digital Signal Processor

    CERN Document Server

    Malik, Muhammad Yasir

    2011-01-01

    RSA(Rivest, Shamir and Adleman)is being used as a public key exchange and key agreement tool for many years. Due to large numbers involved in RSA, there is need for more efficient methods in implementation for public key cryptosystems. Elliptic Curve Cryptography(ECC) is based on elliptic curves defined over a finite field. Elliptic curve cryptosystems(ECC) were discovered by Victor Miller and Neal Koblitz in 1985.This paper comprises of five sections. Section I is introduction to ECC and its components. Section II describes advantages of ECC schemes and its comparison with RSA. Section III is about some of the applications of ECC. Section IV gives some embedded implementations of ECC. Section V contains ECC implementation on fixed point Digital Signal Processor(TMS320VC5416). ECC was implemented using general purpose microcontrollers and Field Programmable Gate Arrays (FPGA) before this work. DSP is more powerful than microcontrollers and much economical than FPGA. So this implementation can be efficiently u...

  1. Secure Antnet Routing Algorithm for Scalable Adhoc Networks Using Elliptic Curve Cryptography

    Directory of Open Access Journals (Sweden)

    V. Vijayalakshmi

    2007-01-01

    Full Text Available The secure end-to-end route discovery in the decentralized Mobile Adhoc Networks (MANETs should have to meet the requirements of prevention of DoS attacks on data traffic, should be adaptive and fault tolerant and must have high speed, low energy overhead and scalability for future development. In this research a secure routing using antnet mechanism and mutual authentication using Elliptic Curve Cryptography (ECC has been proposed to meet the above requirements. The common perception of public key cryptography is that it is not well suited for adhoc networks as they are very complex and slow. Against this popular belief, this research implements Elliptic Curve Cryptography -a public key cryptography scheme. ECC provides a similar level of security to conventional integer-based public-key algorithms, but with much shorter keys. Because of the shorter keys ECC algorithms run faster, require less space and consume less energy. These advantages make ECC a better choice of public key cryptography, especially for a resource constrained systems like MANETs. Using the antnet routing algorithm, the highly trustable route will be selected for data transfer and each Mobile Node (MN in MANET maintains the trust value of its one-hop neighbors. The mutual authentication between source and destination is done by master key exchange using Elliptic Curve Cryptography (ECC. v

  2. Design of an Elliptic Curve Cryptography processor for RFID tag chips.

    Science.gov (United States)

    Liu, Zilong; Liu, Dongsheng; Zou, Xuecheng; Lin, Hui; Cheng, Jian

    2014-09-26

    Radio Frequency Identification (RFID) is an important technique for wireless sensor networks and the Internet of Things. Recently, considerable research has been performed in the combination of public key cryptography and RFID. In this paper, an efficient architecture of Elliptic Curve Cryptography (ECC) Processor for RFID tag chip is presented. We adopt a new inversion algorithm which requires fewer registers to store variables than the traditional schemes. A new method for coordinate swapping is proposed, which can reduce the complexity of the controller and shorten the time of iterative calculation effectively. A modified circular shift register architecture is presented in this paper, which is an effective way to reduce the area of register files. Clock gating and asynchronous counter are exploited to reduce the power consumption. The simulation and synthesis results show that the time needed for one elliptic curve scalar point multiplication over GF(2163) is 176.7 K clock cycles and the gate area is 13.8 K with UMC 0.13 μm Complementary Metal Oxide Semiconductor (CMOS) technology. Moreover, the low power and low cost consumption make the Elliptic Curve Cryptography Processor (ECP) a prospective candidate for application in the RFID tag chip.

  3. On the Mordell-Weil group of elliptic curves induced by families of Diophantine triples

    OpenAIRE

    Mikić, Miljen

    2015-01-01

    The problem of the extendibility of Diophantine triples is closely connected with the Mordell-Weil group of the associated elliptic curve. In this paper, we examine Diophantine triples $\\{k-1,k+1,c_l(k)\\}$ and prove that the torsion group of the associated curves is $\\mathbb{Z}/2\\mathbb{Z} \\times \\mathbb{Z}/2\\mathbb{Z}$ for $l=3,4$ and $l\\equiv 1$ or $2 \\pmod{4}$. Additionally, we prove that the rank is greater than or equal to 2 for all $l\\ge2$. This represents an improvement of previous res...

  4. Design And Implementation of Low Area/Power Elliptic Curve Digital Signature Hardware Core

    Directory of Open Access Journals (Sweden)

    Anissa Sghaier

    2017-06-01

    Full Text Available The Elliptic Curve Digital Signature Algorithm(ECDSA is the analog to the Digital Signature Algorithm(DSA. Based on the elliptic curve, which uses a small key compared to the others public-key algorithms, ECDSA is the most suitable scheme for environments where processor power and storage are limited. This paper focuses on the hardware implementation of the ECDSA over elliptic curveswith the 163-bit key length recommended by the NIST (National Institute of Standards and Technology. It offers two services: signature generation and signature verification. The proposed processor integrates an ECC IP, a Secure Hash Standard 2 IP (SHA-2 Ip and Random Number Generator IP (RNG IP. Thus, all IPs will be optimized, and different types of RNG will be implemented in order to choose the most appropriate one. A co-simulation was done to verify the ECDSA processor using MATLAB Software. All modules were implemented on a Xilinx Virtex 5 ML 50 FPGA platform; they require respectively 9670 slices, 2530 slices and 18,504 slices. FPGA implementations represent generally the first step for obtaining faster ASIC implementations. Further, the proposed design was also implemented on an ASIC CMOS 45-nm technology; it requires a 0.257 mm2 area cell achieving a maximum frequency of 532 MHz and consumes 63.444 (mW. Furthermore, in this paper, we analyze the security of our proposed ECDSA processor against the no correctness check for input points and restart attacks.

  5. Non-Simply-Connected Gauge Groups and Rational Points on Elliptic Curves

    CERN Document Server

    Aspinwall, Paul S; Aspinwall, Paul S.; Morrison, David R.

    1998-01-01

    We consider the F-theory description of non-simply-connected gauge groups appearing in the E8 x E8 heterotic string. The analysis is closely tied to the arithmetic of torsion points on an elliptic curve. The general form of the corresponding elliptic fibration is given for all finite subgroups of E8 which are applicable in this context. We also study the closely-related question of point-like instantons on a K3 surface whose holonomy is a finite group. As an example we consider the case of the heterotic string on a K3 surface having the E8 gauge symmetry broken to (E6 x SU(3))/Z3 or SU(9)/Z3 by point-like instantons with Z3 holonomy.

  6. SPEED UP RATIONAL POINT SCALAR MULTIPLICATIONS ON ELLIPTIC CURVES BY FROBENIUS EQUATIONS

    Institute of Scientific and Technical Information of China (English)

    You Lin; Zhao Junzhong; Xu Maozhi

    2006-01-01

    Let q be a power of a prime and φ be the Frobenius endomorphism on E(Fqk), then q = tφ- φ2.Applying this equation, a new algorithm to compute rational point scalar multiplications on elliptic curves by finding a suitable small positive integer s such that qs can be represented as some very sparse φ-polynomial is proposed. If a Normal Basis (NB) or Optimal Normal Basis (ONB) is applied and the precomputations are considered free, our algorithm will cost, on average, about 55% to 80% less than binary method, and about rithm. In addition, an effective algorithm is provided for finding such integer s.

  7. Efficient Dynamic Threshold Group Signature Scheme Based on Elliptic Curve Cryptosystem

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The short secret key characteristic of elliptic curve cryptosystem (ECC) are integrated with the (t,n ) threshold method to create a practical threshold group signature scheme characterized by simultaneous signing. The scheme not only meets the requirements of anonymity and traceability of group signature but also can withstand Tseng and Wangs conspiracy attack. It allows the group manager to add new members and delete old members according to actual application, while the system parameters have a little change. Cryptanalysis result shows that the scheme is efficient and secure.

  8. USING MODIFIED STERN SERIES FOR DIGITAL SIGNATURE AUTHENTICATION IN ELLIPTIC CURVE CRYPTOGRAPHY

    Directory of Open Access Journals (Sweden)

    Latha Parthiban

    2011-12-01

    Full Text Available This paper presents the generation of digital signature along with message recovery based on Elliptic Curve Cryptography (ECC and knapsack algorithm. In digital signature along with message recovery scheme, signature alone is sent and message is recovered from the signature (r, s. ECC provides greater security with less key size, when compared to integer factorization and discrete logarithm system. As the strength of knapsack algorithm depends on the selection of the series, the proposed algorithm uses modified Stern series which not only reduces the time complexity but also provides better security.

  9. A secure RFID mutual authentication protocol for healthcare environments using elliptic curve cryptography.

    Science.gov (United States)

    Jin, Chunhua; Xu, Chunxiang; Zhang, Xiaojun; Zhao, Jining

    2015-03-01

    Radio Frequency Identification(RFID) is an automatic identification technology, which can be widely used in healthcare environments to locate and track staff, equipment and patients. However, potential security and privacy problems in RFID system remain a challenge. In this paper, we design a mutual authentication protocol for RFID based on elliptic curve cryptography(ECC). We use pre-computing method within tag's communication, so that our protocol can get better efficiency. In terms of security, our protocol can achieve confidentiality, unforgeability, mutual authentication, tag's anonymity, availability and forward security. Our protocol also can overcome the weakness in the existing protocols. Therefore, our protocol is suitable for healthcare environments.

  10. Fast algorithms for computing isogenies between ordinary elliptic curves in small characteristic

    CERN Document Server

    De Feo, Luca

    2010-01-01

    The problem of computing an explicit isogeny between two given elliptic curves over F_q, originally motivated by point counting, has recently awaken new interest in the cryptology community thanks to the works of Teske and Rostovstev & Stolbunov. While the large characteristic case is well understood, only suboptimal algorithms are known in small characteristic; they are due to Couveignes, Lercier, Lercier & Joux and Lercier & Sirvent. In this paper we discuss the differences between them and run some comparative experiments. We also present the first complete implementation of Couveignes' second algorithm and present improvements that make it the algorithm having the best asymptotic complexity in the degree of the isogeny.

  11. An efficient hardware architecture of a scalable elliptic curve crypto-processor over GF(2n)

    Science.gov (United States)

    Tawalbeh, Lo'ai; Tenca, Alexandre; Park, Song; Koc, Cetin

    2005-08-01

    This paper presents a scalable Elliptic Curve Crypto-Processor (ECCP) architecture for computing the point multiplication for curves defined over the binary extension fields (GF(2n)). This processor computes modular inverse and Montgomery modular multiplication using a new effcient algorithm. The scalability feature of the proposed crypto-processor allows a fixed-area datapath to handle operands of any size. Also, the word size of the datapath can be adjusted to meet the area and performance requirements. On the other hand, the processor is reconfigurable in the sense that the user has the ability to choose the value of the field parameter (n). Experimental results show that the proposed crypto-processor is competitive with many other previous designs.

  12. Composite Field Multiplier based on Look-Up Table for Elliptic Curve Cryptography Implementation

    Directory of Open Access Journals (Sweden)

    Marisa W. Paryasto

    2013-09-01

    Full Text Available Implementing a secure cryptosystem requires operations involving hundreds of bits. One of the most recommended algorithm is Elliptic Curve Cryptography (ECC. The complexity of elliptic curve algorithms and parameters with hundreds of bits requires specific design and implementation strategy. The design architecture must be customized according to security requirement, available resources and parameter choices. In this work we propose the use of composite field to implement finite field multiplication for ECC implementation. We use 299-bit keylength represented in GF((21323 instead of in GF(2299. Composite field multiplier can be implemented using different multiplier for ground-field and for extension field. In this paper, LUT is used for multiplication in the ground-field and classic multiplieris used for the extension field multiplication. A generic architecture for the multiplier is presented. Implementation is done with VHDL with the target device Altera DE2. The work in this paper uses the simplest algorithm to confirm the idea that by dividing field into composite, use different multiplier for base and extension field would give better trade-off for time and area. This work will be the beginning of our more advanced further research that implements composite-field using Mastrovito Hybrid, KOA and LUT.

  13. System Level Design of Reconfigurable Server Farms Using Elliptic Curve Cryptography Processor Engines

    Directory of Open Access Journals (Sweden)

    Sangook Moon

    2014-01-01

    Full Text Available As today’s hardware architecture becomes more and more complicated, it is getting harder to modify or improve the microarchitecture of a design in register transfer level (RTL. Consequently, traditional methods we have used to develop a design are not capable of coping with complex designs. In this paper, we suggest a way of designing complex digital logic circuits with a soft and advanced type of SystemVerilog at an electronic system level. We apply the concept of design-and-reuse with a high level of abstraction to implement elliptic curve crypto-processor server farms. With the concept of the superior level of abstraction to the RTL used with the traditional HDL design, we successfully achieved the soft implementation of the crypto-processor server farms as well as robust test bench code with trivial effort in the same simulation environment. Otherwise, it could have required error-prone Verilog simulations for the hardware IPs and other time-consuming jobs such as C/SystemC verification for the software, sacrificing more time and effort. In the design of the elliptic curve cryptography processor engine, we propose a 3X faster GF(2m serial multiplication architecture.

  14. Elliptic curves and their torsion subgroups over number fields of type (2, 2,

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Suppose that E:y2=x(x+M)(x+N) is an elliptic curve, where Melliptic curve E over any number field F, it is shown that E(L)tors=E(F)tors holds for almost all extensions L/F of degree p(a prime number). These results have remarkably developed the recent results by Kwon about torsion subgroups over quadratic fields.

  15. Hardware Realization of Fast Multi-Scalar Elliptic Curve Point Multiplication by Reducing the Hamming Weights Over GF(p

    Directory of Open Access Journals (Sweden)

    Nagaraja Shylashree

    2014-09-01

    Full Text Available We present a new hardware realization of fast elliptic curve Multi-Scalar Point Multiplication (MSPM using the sum of products expansion of the scalars. In Elliptic curve point Multiplication latency depends on the number of one’s (Hamming Weight in the binary representation of the scalar multiplier. By reducing the effective number of one’s in the multiplier, the multiplication speed is automatically increased. Therefore we describe a new method of effectively reducing the Hamming weight of the scalar multipliers thereby reduces the number of Point Adders when multi scalar multiplication is needed. The increase in speed achieved outweighs the hardware cost and complexity.

  16. Secure and efficient elliptic curve cryptography resists side-channel attacks

    Institute of Scientific and Technical Information of China (English)

    Zhang Tao; Fan Mingyu; Zheng Xiaoyu

    2009-01-01

    An embedded cryptosystem needs higher reconfiguration capability and security. After analyzing the newly emerging side-channel attacks on elliptic curve cryptosystem (ECC), an efficient fractional width-w NAF (FWNAF) algorithm is proposed to secure ECC scalar multiplication from these attacks. This algorithm adopts the fractional window method and probabilistic SPA scheme to recondigure the pre-computed table, and it allows designers to make a dynamic configuration on pre-computed table. And then, it is enhanced to resist SPA, DPA, RPA and ZPA attacks by using the random masking method. Compared with the WBRIP and EBRIP methods, our proposals has the lowest total computation cost and reduce the shake phenomenon due to sharp fluctuation on computation performance.

  17. A Criterion for Elliptic Curves with Second Lowest 2-Power in L(1)(Ⅱ)

    Institute of Scientific and Technical Information of China (English)

    Chun Lai ZHAO

    2005-01-01

    Let D = p1p2… pm, where pi, p2,...,pm are distinct rational primes with p1 ≡ p2 ≡3(mod 8), pi ≡1(mod 8)(3 ≤ i ≤ m), and m is any positive integer. In this paper, we give a simple combinatorial criterion for the value of the complex L-function of the congruent elliptic curve ED2 : y2 = x3-D2x at s = 1, divided by the period ω defined below, to be exactly divisible by 22m-2, the second lowest 2-power with respect to the number of the Gaussian prime factors of D. As a corollary, we obtain a new series of non-congruent numbers whose prime factors can be arbitrarily many. Our result is in accord with the predictions of the conjecture of Birch and Swinnerton-Dyer.

  18. An efficient RFID authentication protocol to enhance patient medication safety using elliptic curve cryptography.

    Science.gov (United States)

    Zhang, Zezhong; Qi, Qingqing

    2014-05-01

    Medication errors are very dangerous even fatal since it could cause serious even fatal harm to patients. In order to reduce medication errors, automated patient medication systems using the Radio Frequency Identification (RFID) technology have been used in many hospitals. The data transmitted in those medication systems is very important and sensitive. In the past decade, many security protocols have been proposed to ensure its secure transition attracted wide attention. Due to providing mutual authentication between the medication server and the tag, the RFID authentication protocol is considered as the most important security protocols in those systems. In this paper, we propose a RFID authentication protocol to enhance patient medication safety using elliptic curve cryptography (ECC). The analysis shows the proposed protocol could overcome security weaknesses in previous protocols and has better performance. Therefore, the proposed protocol is very suitable for automated patient medication systems.

  19. Two-Factor User Authentication with Key Agreement Scheme Based on Elliptic Curve Cryptosystem

    Directory of Open Access Journals (Sweden)

    Juan Qu

    2014-01-01

    Full Text Available A password authentication scheme using smart card is called two-factor authentication scheme. Two-factor authentication scheme is the most accepted and commonly used mechanism that provides the authorized users a secure and efficient method for accessing resources over insecure communication channel. Up to now, various two-factor user authentication schemes have been proposed. However, most of them are vulnerable to smart card loss attack, offline password guessing attack, impersonation attack, and so on. In this paper, we design a password remote user authentication with key agreement scheme using elliptic curve cryptosystem. Security analysis shows that the proposed scheme has high level of security. Moreover, the proposed scheme is more practical and secure in contrast to some related schemes.

  20. On local-global divisibility by $p^n$ in elliptic curves

    CERN Document Server

    Paladino, Laura; Viada, Evelina

    2011-01-01

    Let $ p $ be a prime number and let $k$ be a number field, which does not contain the field $\\mathbb{Q} (\\zeta_p + \\bar{\\zeta_p})$. Let $\\mathcal{E}$ be an elliptic curve defined over $k$. We prove that if there are no $k$-rational torsion points of exact order $p$ on $\\mathcal{E}$, then the local-global principle holds for divisibility by $p^n$, with $n$ a natural number. As a consequence of the deep theorems of Merel, Mazur and Kamienny we deduce that, for $p$ larger than a constant $C ([k:\\mathbb{Q}])$, depending only on the degree of $k$, there are no counterexamples to the local-global divisibility principle. In particular, for the rational numbers $C(1)=7$ and for quadratic fields $C(2)=13$.

  1. Bagger-Witten line bundles on moduli spaces of elliptic curves

    CERN Document Server

    Gu, W

    2016-01-01

    In this paper we discuss Bagger-Witten line bundles over moduli spaces of SCFTs. We review how in general they are `fractional' line bundles, not honest line bundles, twisted on triple overlaps. We discuss the special case of moduli spaces of elliptic curves in detail. There, the Bagger-Witten line bundles does not exist as an ordinary line bundle, but rather is necessarily fractional. As a fractional line bundle, it is nontrivial (though torsion) over the uncompactified moduli stack, and its restriction to the interior, excising corners with enhanced stabilizers, is also fractional. We review and compare to results of recent work arguing that well-definedness of the worldsheet metric implies that the Bagger-Witten line bundle is torsion, and give general arguments on the existence of universal structures on moduli spaces of SCFTs, in which superconformal deformation parameters are promoted to nondynamical fields ranging over the SCFT moduli space.

  2. Mordell-Weil groups and Selmer groups of twin-prime elliptic curves

    Institute of Scientific and Technical Information of China (English)

    邱德荣; 张贤科

    2002-01-01

    Let E = Eσ : y2 = x(x + σp)(x + σq) be elliptic curves, where σ = ±1, p and q are primenumbers with p+2 = q. (i) Selmer groups S(2)(E/Q), S(φ)(E/Q), and S(φ)(E/Q) are explicitly determined,e.g. S(2)(E+1/Q)= (Z/2Z)2, (Z/2Z)3, and (Z/2Z)4 when p ≡ 5, 1 (or 3), and 7(mod 8), respectively. (ii)When p ≡ 5 (3, 5 for σ = -1) (mod 8), it is proved that the Mordell-Weil group E(Q) ≌ Z/2Z Z/2Z,symbol, the torsion subgroup E(K)tors for any number field K, etc. are also obtained.

  3. Elliptic Curve Based Zero Knowledge Proofs and Their Applicability on Resource Constrained Devices

    CERN Document Server

    Chatzigiannakis, Ioannis; Spirakis, Paul G; Stamatiou, Yannis C

    2011-01-01

    Elliptic Curve Cryptography (ECC) is an attractive alternative to conventional public key cryptography, such as RSA. ECC is an ideal candidate for implementation on constrained devices where the major computational resources i.e. speed, memory are limited and low-power wireless communication protocols are employed. That is because it attains the same security levels with traditional cryptosystems using smaller parameter sizes. Moreover, in several application areas such as person identification and eVoting, it is frequently required of entities to prove knowledge of some fact without revealing this knowledge. Such proofs of knowledge are called Zero Knowledge Interactive Proofs (ZKIP) and involve interactions between two communicating parties, the Prover and the Verifier. In a ZKIP, the Prover demonstrates the possesion of some information (e.g. authentication information) to the Verifier without disclosing it. In this paper, we focus on the application of ZKIP protocols on resource constrained devices. We st...

  4. A User Authentication Scheme Based on Elliptic Curves Cryptography for Wireless Ad Hoc Networks.

    Science.gov (United States)

    Chen, Huifang; Ge, Linlin; Xie, Lei

    2015-07-14

    The feature of non-infrastructure support in a wireless ad hoc network (WANET) makes it suffer from various attacks. Moreover, user authentication is the first safety barrier in a network. A mutual trust is achieved by a protocol which enables communicating parties to authenticate each other at the same time and to exchange session keys. For the resource-constrained WANET, an efficient and lightweight user authentication scheme is necessary. In this paper, we propose a user authentication scheme based on the self-certified public key system and elliptic curves cryptography for a WANET. Using the proposed scheme, an efficient two-way user authentication and secure session key agreement can be achieved. Security analysis shows that our proposed scheme is resilient to common known attacks. In addition, the performance analysis shows that our proposed scheme performs similar or better compared with some existing user authentication schemes.

  5. Attack on Digital Multi-Signature Scheme Based on Elliptic Curve Cryptosystem

    Institute of Scientific and Technical Information of China (English)

    Duo Liu; Ping Luo; Yi-Qi Dai

    2007-01-01

    The concept of multisignature, in which multiple signers can cooperate to sign the same message and any verifier can verify the validity of the multi-signature, was first introduced by Itakura and Nakamura.Several multisignature schemes have been proposed since.Chen et al.proposed a new digital multi-signature scheme based on the elliptic curve cryptosystem recently.In this paper, we show that their scheme is insecure, for it is vulnerable to the so-called active attacks, such as the substitution of a "false" public key to a "true" one in a key directory or during transmission.And then the attacker can sign a legal signature which other users have signed and forge a signature himself which can be accepted by the verifier.

  6. Hardware Activation by Means of PUFs and Elliptic Curve Cryptography in Field-Programmable Devices

    Directory of Open Access Journals (Sweden)

    Luis Parrilla

    2016-01-01

    Full Text Available Reusable design using IP cores requires of efficient methods for protecting the Intellectual Property of the designer and the corresponding license agreements. In this work, a new protection procedure establishing an activation protocol in a similar way to the activation process in the software world is presented. The procedure, named SEHAS (Secure Hardware Activation System allows the distribution of cores in either Blocked (not functioning or Demo (functioning with limited features modes, while ensuring the license agreements by identifying not only the IP core but also the implementation device, using Physically Unclonable Functions (PUF. Moreover, SEHAS secures the exchange of information between the core and the core vendor using an Elliptic Curve Cryptosystem (ECC. This secure channel allows the IP core vendor to send a unique Activation Code to the core in order to switch it to the Activated Mode, thus enabling all its features.

  7. A singular property of the supersingular elliptic curve in characteristic 2

    CERN Document Server

    Zapponi, Leonardo

    2010-01-01

    Let $E$ be the supersingular elliptic curve defined over the field $k=\\bar{\\bold F}_2$, which is unique up to $k$-isomorphism. Denote by $0_E$ its identity element and let $C\\cong\\bold A^1_k$ the quotient of $E-\\{0_E\\}$ under the action of the group $\\mbox{Isom}_k(E)$ (which is non-abelian, of order $24$). The main result of this paper asserts that the set $C(k)$ naturally parametrizes $k$-isomorphism classes of Lam\\'e covers, which are tamely ramified covers $X\\to\\bold P^1$ unramified outside three points having a particular ramification datum. This fact is surprising for two reasons: first of all, it is the first non-trivial example of a family of covers of the projective line unramified outside three points which is parametrized by the geometric points of a curve. Moreover, when considered in arbitrary characteristic, the explicit construction of Lam\\'e covers is quite involved and their arithmetic properties still remain misterious. The simplicity of the problem in characteristic $2$ has many deep consequ...

  8. An Elliptic Curve Based Schnorr Cloud Security Model in Distributed Environment.

    Science.gov (United States)

    Muthurajan, Vinothkumar; Narayanasamy, Balaji

    2016-01-01

    Cloud computing requires the security upgrade in data transmission approaches. In general, key-based encryption/decryption (symmetric and asymmetric) mechanisms ensure the secure data transfer between the devices. The symmetric key mechanisms (pseudorandom function) provide minimum protection level compared to asymmetric key (RSA, AES, and ECC) schemes. The presence of expired content and the irrelevant resources cause unauthorized data access adversely. This paper investigates how the integrity and secure data transfer are improved based on the Elliptic Curve based Schnorr scheme. This paper proposes a virtual machine based cloud model with Hybrid Cloud Security Algorithm (HCSA) to remove the expired content. The HCSA-based auditing improves the malicious activity prediction during the data transfer. The duplication in the cloud server degrades the performance of EC-Schnorr based encryption schemes. This paper utilizes the blooming filter concept to avoid the cloud server duplication. The combination of EC-Schnorr and blooming filter efficiently improves the security performance. The comparative analysis between proposed HCSA and the existing Distributed Hash Table (DHT) regarding execution time, computational overhead, and auditing time with auditing requests and servers confirms the effectiveness of HCSA in the cloud security model creation.

  9. An Elliptic Curve Based Schnorr Cloud Security Model in Distributed Environment

    Science.gov (United States)

    Muthurajan, Vinothkumar; Narayanasamy, Balaji

    2016-01-01

    Cloud computing requires the security upgrade in data transmission approaches. In general, key-based encryption/decryption (symmetric and asymmetric) mechanisms ensure the secure data transfer between the devices. The symmetric key mechanisms (pseudorandom function) provide minimum protection level compared to asymmetric key (RSA, AES, and ECC) schemes. The presence of expired content and the irrelevant resources cause unauthorized data access adversely. This paper investigates how the integrity and secure data transfer are improved based on the Elliptic Curve based Schnorr scheme. This paper proposes a virtual machine based cloud model with Hybrid Cloud Security Algorithm (HCSA) to remove the expired content. The HCSA-based auditing improves the malicious activity prediction during the data transfer. The duplication in the cloud server degrades the performance of EC-Schnorr based encryption schemes. This paper utilizes the blooming filter concept to avoid the cloud server duplication. The combination of EC-Schnorr and blooming filter efficiently improves the security performance. The comparative analysis between proposed HCSA and the existing Distributed Hash Table (DHT) regarding execution time, computational overhead, and auditing time with auditing requests and servers confirms the effectiveness of HCSA in the cloud security model creation. PMID:26981584

  10. Pseudorandom Bit Sequence Generator for Stream Cipher Based on Elliptic Curves

    Directory of Open Access Journals (Sweden)

    Jilna Payingat

    2015-01-01

    Full Text Available This paper proposes a pseudorandom sequence generator for stream ciphers based on elliptic curves (EC. A detailed analysis of various EC based random number generators available in the literature is done and a new method is proposed such that it addresses the drawbacks of these schemes. Statistical analysis of the proposed method is carried out using the NIST (National Institute of Standards and Technology test suite and it is seen that the sequence exhibits good randomness properties. The linear complexity analysis shows that the system has a linear complexity equal to the period of the sequence which is highly desirable. The statistical complexity and security against known plain text attack are also analysed. A comparison of the proposed method with other EC based schemes is done in terms of throughput, periodicity, and security, and the proposed method outperforms the methods in the literature. For resource constrained applications where a highly secure key exchange is essential, the proposed method provides a good option for encryption by time sharing the point multiplication unit for EC based key exchange. The algorithm and architecture for implementation are developed in such a way that the hardware consumed in addition to point multiplication unit is much less.

  11. On Elliptic Curve Primality Proving%关于椭圆曲线素性证明

    Institute of Scientific and Technical Information of China (English)

    张李军

    2008-01-01

    This paper describes the Atkin's elliptic curves primality proving algorithm and discusses all implementationdetails of this algorithm. Finally it gives the implemention of this algorithm by software and exhibits an example explicitly.This algorithm is implemented with software and this software is used to test some general large integers and acquire agood testing result. For the purpose of understanding this algorithm more clearly, a typical example is provided finally.%文章给出了由Atkin提出的一种非常有效的素性测试方法即椭圆曲线素性证明算法,详细讨论了具体实施该算法的所有细节,而且通过在计算机上编程获得了其软件实现,并用该软件来测试一般的大整数的素性,取得了很好的效果.为了清晰地展示该算法的过程,文章在最后给出了一个详细的算例.

  12. Resource efficiency of hardware extensions of a 4-issue VLIW processor for elliptic curve cryptography

    Science.gov (United States)

    Jungeblut, T.; Puttmann, C.; Dreesen, R.; Porrmann, M.; Thies, M.; Rückert, U.; Kastens, U.

    2010-12-01

    The secure transmission of data plays a significant role in today's information era. Especially in the area of public-key-cryptography methods, which are based on elliptic curves (ECC), gain more and more importance. Compared to asymmetric algorithms, like RSA, ECC can be used with shorter key lengths, while achieving an equal level of security. The performance of ECC-algorithms can be increased significantly by adding application specific hardware extensions. Due to their fine grained parallelism, VLIW-processors are well suited for the execution of ECC algorithms. In this work, we extended the fourfold parallel CoreVA-VLIW-architecture by several hardware accelerators to increase the resource efficiency of the overall system. For the design-space exploration we use a dual design flow, which is based on the automatic generation of a complete C-compiler based tool chain from a central processor specification. Using the hardware accelerators the performance of the scalar multiplication on binary fields can be increased by the factor of 29. The energy consumption can be reduced by up to 90%. The extended processor hardware was mapped on a current 65 nm low-power standard-cell-technology. The chip area of the CoreVA-VLIW-architecture is 0.24 mm2 at a power consumption of 29 mW/MHz. The performance gain is analyzed in respect to the increased hardware costs, as chip area or power consumption.

  13. A secure RFID authentication protocol for healthcare environments using elliptic curve cryptosystem.

    Science.gov (United States)

    Zhao, Zhenguo

    2014-05-01

    With the fast advancement of the wireless communication technology and the widespread use of medical systems, the radio frequency identification (RFID) technology has been widely used in healthcare environments. As the first important protocol for ensuring secure communication in healthcare environment, the RFID authentication protocols derive more and more attentions. Most of RFID authentication protocols are based on hash function or symmetric cryptography. To get more security properties, elliptic curve cryptosystem (ECC) has been used in the design of RFID authentication protocol. Recently, Liao and Hsiao proposed a new RFID authentication protocol using ECC and claimed their protocol could withstand various attacks. In this paper, we will show that their protocol suffers from the key compromise problem, i.e. an adversary could get the private key stored in the tag. To enhance the security, we propose a new RFID authentication protocol using ECC. Detailed analysis shows the proposed protocol not only could overcome weaknesses in Liao and Hsiao's protocol but also has the same performance. Therefore, it is more suitable for healthcare environments.

  14. Lightweight Data Aggregation Scheme against Internal Attackers in Smart Grid Using Elliptic Curve Cryptography

    Directory of Open Access Journals (Sweden)

    Debiao He

    2017-01-01

    Full Text Available Recent advances of Internet and microelectronics technologies have led to the concept of smart grid which has been a widespread concern for industry, governments, and academia. The openness of communications in the smart grid environment makes the system vulnerable to different types of attacks. The implementation of secure communication and the protection of consumers’ privacy have become challenging issues. The data aggregation scheme is an important technique for preserving consumers’ privacy because it can stop the leakage of a specific consumer’s data. To satisfy the security requirements of practical applications, a lot of data aggregation schemes were presented over the last several years. However, most of them suffer from security weaknesses or have poor performances. To reduce computation cost and achieve better security, we construct a lightweight data aggregation scheme against internal attackers in the smart grid environment using Elliptic Curve Cryptography (ECC. Security analysis of our proposed approach shows that it is provably secure and can provide confidentiality, authentication, and integrity. Performance analysis of the proposed scheme demonstrates that both computation and communication costs of the proposed scheme are much lower than the three previous schemes. As a result of these aforementioned benefits, the proposed lightweight data aggregation scheme is more practical for deployment in the smart grid environment.

  15. Elliptic Curve Cryptography-Based Authentication with Identity Protection for Smart Grids.

    Directory of Open Access Journals (Sweden)

    Liping Zhang

    Full Text Available In a smart grid, the power service provider enables the expected power generation amount to be measured according to current power consumption, thus stabilizing the power system. However, the data transmitted over smart grids are not protected, and then suffer from several types of security threats and attacks. Thus, a robust and efficient authentication protocol should be provided to strength the security of smart grid networks. As the Supervisory Control and Data Acquisition system provides the security protection between the control center and substations in most smart grid environments, we focus on how to secure the communications between the substations and smart appliances. Existing security approaches fail to address the performance-security balance. In this study, we suggest a mitigation authentication protocol based on Elliptic Curve Cryptography with privacy protection by using a tamper-resistant device at the smart appliance side to achieve a delicate balance between performance and security of smart grids. The proposed protocol provides some attractive features such as identity protection, mutual authentication and key agreement. Finally, we demonstrate the completeness of the proposed protocol using the Gong-Needham-Yahalom logic.

  16. Elliptic Curve Cryptography-Based Authentication with Identity Protection for Smart Grids.

    Science.gov (United States)

    Zhang, Liping; Tang, Shanyu; Luo, He

    2016-01-01

    In a smart grid, the power service provider enables the expected power generation amount to be measured according to current power consumption, thus stabilizing the power system. However, the data transmitted over smart grids are not protected, and then suffer from several types of security threats and attacks. Thus, a robust and efficient authentication protocol should be provided to strength the security of smart grid networks. As the Supervisory Control and Data Acquisition system provides the security protection between the control center and substations in most smart grid environments, we focus on how to secure the communications between the substations and smart appliances. Existing security approaches fail to address the performance-security balance. In this study, we suggest a mitigation authentication protocol based on Elliptic Curve Cryptography with privacy protection by using a tamper-resistant device at the smart appliance side to achieve a delicate balance between performance and security of smart grids. The proposed protocol provides some attractive features such as identity protection, mutual authentication and key agreement. Finally, we demonstrate the completeness of the proposed protocol using the Gong-Needham-Yahalom logic.

  17. Security Enhanced User Authentication Protocol for Wireless Sensor Networks Using Elliptic Curves Cryptography

    Directory of Open Access Journals (Sweden)

    Younsung Choi

    2014-06-01

    Full Text Available Wireless sensor networks (WSNs consist of sensors, gateways and users. Sensors are widely distributed to monitor various conditions, such as temperature, sound, speed and pressure but they have limited computational ability and energy. To reduce the resource use of sensors and enhance the security of WSNs, various user authentication protocols have been proposed. In 2011, Yeh et al. first proposed a user authentication protocol based on elliptic curve cryptography (ECC for WSNs. However, it turned out that Yeh et al.’s protocol does not provide mutual authentication, perfect forward secrecy, and key agreement between the user and sensor. Later in 2013, Shi et al. proposed a new user authentication protocol that improves both security and efficiency of Yeh et al.’s protocol. However, Shi et al.’s improvement introduces other security weaknesses. In this paper, we show that Shi et al.’s improved protocol is vulnerable to session key attack, stolen smart card attack, and sensor energy exhausting attack. In addition, we propose a new, security-enhanced user authentication protocol using ECC for WSNs.

  18. Compression of Tate Pairings on Elliptic Curves%椭圆曲线Tate对的压缩

    Institute of Scientific and Technical Information of China (English)

    胡磊

    2007-01-01

    利用有限域包含的循环群之间的映射,给出了特征为素数p,MOV次数为3的超奇异椭圆曲线上的一类Tate对的两种有效压缩方法,它们分别将Tate对的值从6logp比特长的串压缩到3logp和2logp比特长.两种压缩方法的实现均使用原有Tate对的优化算法的代码,不需要针对压缩对编写新的实现代码,而且两种压缩对的实现均保持原有Tate对的实现速度.%In this paper, utilizing maps between cyclic groups contained in a finite field, two efficient methods for compressing a Tate pairing defined on a supersingular elliptic curve with prime characteristic p and MOV degree 3 are presented. They compress a pairing value from a string of length of 6logp bits to ones of 3logp and 2logp bits, respectively, and an implementation for both the compressed pairings makes use of the codes for the optimized algorithm of the original pairing and no new code is needed. Both the compressed pairings achieve the speed of the original implementation.

  19. Optical identity authentication scheme based on elliptic curve digital signature algorithm and phase retrieval algorithm.

    Science.gov (United States)

    Fan, Desheng; Meng, Xiangfeng; Wang, Yurong; Yang, Xiulun; Peng, Xiang; He, Wenqi; Dong, Guoyan; Chen, Hongyi

    2013-08-10

    An optical identity authentication scheme based on the elliptic curve digital signature algorithm (ECDSA) and phase retrieval algorithm (PRA) is proposed. In this scheme, a user's certification image and the quick response code of the user identity's keyed-hash message authentication code (HMAC) with added noise, serving as the amplitude and phase restriction, respectively, are digitally encoded into two phase keys using a PRA in the Fresnel domain. During the authentication process, when the two phase keys are presented to the system and illuminated by a plane wave of correct wavelength, an output image is generated in the output plane. By identifying whether there is a match between the amplitude of the output image and all the certification images pre-stored in the database, the system can thus accomplish a first-level verification. After the confirmation of first-level verification, the ECDSA signature is decoded from the phase part of the output image and verified to allege whether the user's identity is legal or not. Moreover, the introduction of HMAC makes it almost impossible to forge the signature and hence the phase keys thanks to the HMAC's irreversible property. Theoretical analysis and numerical simulations both validate the feasibility of our proposed scheme.

  20. Instanton geometry and quantum A{sub {infinity}} structure on the elliptic curve

    Energy Technology Data Exchange (ETDEWEB)

    Herbst, M. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Lerche, W. [European Lab. for Particle Physics (CERN), Geneva (Switzerland); Nemeschansky, D. [University of Southern California, Los Angeles, CA (United States). Dept. of Physics

    2006-03-15

    We first determine and then study the complete set of non-vanishing A-model correlation functions associated with the 'long-diagonal branes' on the elliptic curve. We verify that they satisfy the relevant A{sub {infinity}} consistency relations at both classical and quantum levels. In particular we find that the A{sub {infinity}} relation for the annulus provides a reconstruction of annulus instantons out of disk instantons. We note in passing that the naive application of the Cardy-constraint does not hold for our correlators, confirming expectations. Moreover, we analyze various analytical properties of the correlators, including instanton flops and the mixing of correlators with different numbers of legs under monodromy. The classical and quantum A{sub {infinity}} relations turn out to be compatible with such homotopy transformations. They lead to a non-invariance of the effective action under modular transformations, unless compensated by suitable contact terms which amount to redefinitions of the tachyon fields. (orig.)

  1. Security enhanced user authentication protocol for wireless sensor networks using elliptic curves cryptography.

    Science.gov (United States)

    Choi, Younsung; Lee, Donghoon; Kim, Jiye; Jung, Jaewook; Nam, Junghyun; Won, Dongho

    2014-06-10

    Wireless sensor networks (WSNs) consist of sensors, gateways and users. Sensors are widely distributed to monitor various conditions, such as temperature, sound, speed and pressure but they have limited computational ability and energy. To reduce the resource use of sensors and enhance the security of WSNs, various user authentication protocols have been proposed. In 2011, Yeh et al. first proposed a user authentication protocol based on elliptic curve cryptography (ECC) for WSNs. However, it turned out that Yeh et al.'s protocol does not provide mutual authentication, perfect forward secrecy, and key agreement between the user and sensor. Later in 2013, Shi et al. proposed a new user authentication protocol that improves both security and efficiency of Yeh et al.'s protocol. However, Shi et al.'s improvement introduces other security weaknesses. In this paper, we show that Shi et al.'s improved protocol is vulnerable to session key attack, stolen smart card attack, and sensor energy exhausting attack. In addition, we propose a new, security-enhanced user authentication protocol using ECC for WSNs.

  2. Three-Factor User Authentication and Key Agreement Using Elliptic Curve Cryptosystem in Wireless Sensor Networks.

    Science.gov (United States)

    Park, YoHan; Park, YoungHo

    2016-12-14

    Secure communication is a significant issue in wireless sensor networks. User authentication and key agreement are essential for providing a secure system, especially in user-oriented mobile services. It is also necessary to protect the identity of each individual in wireless environments to avoid personal privacy concerns. Many authentication and key agreement schemes utilize a smart card in addition to a password to support security functionalities. However, these schemes often fail to provide security along with privacy. In 2015, Chang et al. analyzed the security vulnerabilities of previous schemes and presented the two-factor authentication scheme that provided user privacy by using dynamic identities. However, when we cryptanalyzed Chang et al.'s scheme, we found that it does not provide sufficient security for wireless sensor networks and fails to provide accurate password updates. This paper proposes a security-enhanced authentication and key agreement scheme to overcome these security weaknesses using biometric information and an elliptic curve cryptosystem. We analyze the security of the proposed scheme against various attacks and check its viability in the mobile environment.

  3. Conference Elliptic Curves, Modular Forms and Iwasawa Theory : in honour of John H. Coates' 70th birthday

    CERN Document Server

    Zerbes, Sarah

    2016-01-01

    Celebrating one of the leading figures in contemporary number theory – John H. Coates – on the occasion of his 70th birthday, this collection of contributions covers a range of topics in number theory, concentrating on the arithmetic of elliptic curves, modular forms, and Galois representations. Several of the contributions in this volume were presented at the conference Elliptic Curves, Modular Forms and Iwasawa Theory, held in honour of the 70th birthday of John Coates in Cambridge, March 25-27, 2015. The main unifying theme is Iwasawa theory, a field that John Coates himself has done much to create. This collection is indispensable reading for researchers in Iwasawa theory, and is interesting and valuable for those in many related fields. .

  4. Pulsating Different Curves of Zero Velocity around Triangular Equilibrium Points in Elliptical Restricted Three-Body Problem

    Directory of Open Access Journals (Sweden)

    A. Narayan

    2013-01-01

    Full Text Available The oblateness and the photogravitational effects of both the primaries on the location and the stability of the triangular equilibrium points in the elliptical restricted three-body problem have been discussed. The stability of the triangular points under the photogravitational and oblateness effects of both the primaries around the binary systems Achird, Lyeten, Alpha Cen-AB, Kruger 60, and Xi-Bootis, has been studied using simulation techniques by drawing different curves of zero velocity.

  5. René Schoof's Algorithm for Determining the Order of the Group of Points on an Elliptic Curve over a Finite Field

    OpenAIRE

    McGee, John J.

    2006-01-01

    Elliptic curves have a rich mathematical history dating back to Diophantus (c. 250 C.E.), who used a form of these cubic equations to find right triangles of integer area with rational sides. In more recent times the deep mathematics of elliptic curves was used by Andrew Wiles et. al., to construct a proof of Fermat's last theorem, a problem which challenged mathematicians for more than 300 years. In addition, elliptic curves over finite fields find practical application in the areas of cr...

  6. Secure Ubiquitous Sensor Network based on Elliptic Curve MenezesQu Vanstoneas Status Data Supply of EnvironmentinDisaster Management

    Directory of Open Access Journals (Sweden)

    Ismed Jauhar

    2016-03-01

    Full Text Available Along with the many environmental changes, it enables a disaster either natural or man-made objects. One of the efforts made to prevent disasters from happening is to make a system that is able to provide information about the status of the environment that is around. Many developments in the sensor system makes it possible to load a system that will supply real-time on the status of environmental conditions with a good security system. This study created a supply system status data of environmental conditions, especially on bridges by using Ubiquitous Sensor Network. Sensor used to detect vibrations are using an accelerometer. Supply of data between sensors and servers using ZigBee communication protocol wherein the data communication will be done using the Elliptic Curve Integrated security mechanisms Encryption Scheme and on the use of Elliptic Curve key aggrement Menezes-Qu-Vanstone. Test results show the limitation of distance for communication is as far as 55 meters, with the computation time for encryption and decryption with 97 and 42 seconds extra time for key exchange is done at the beginning of communication . Keywords: Ubiquitous Sensor Network, Accelerometer, ZigBee,Elliptic Curve Menezes-Qu-Vanstone

  7. From Holonomy of the Ising Model Form Factors to n-Fold Integrals and the Theory of Elliptic Curves

    Directory of Open Access Journals (Sweden)

    Salah Boukraa

    2007-10-01

    Full Text Available We recall the form factors $f^(j_{N,N}$ corresponding to the $lambda$-extension $C(N,N; lambda$ of the two-point diagonal correlation function of the Ising model on the square lattice and their associated linear differential equations which exhibit both a "Russian-doll" nesting, and a decomposition of the linear differential operators as a direct sum of operators (equivalent to symmetric powers of the differential operator of the complete elliptic integral $E$. The scaling limit of these differential operators breaks the direct sum structure but not the "Russian doll" structure, the "scaled" linear differential operators being no longer Fuchsian. We then introduce some multiple integrals of the Ising class expected to have the same singularities as the singularities of the $n$-particle contributions $chi^{(n}$ to the susceptibility of the square lattice Ising model. We find the Fuchsian linear differential equations satisfied by these multiple integrals for $n = 1, 2, 3, 4$ and, only modulo a prime, for $n = 5$ and 6, thus providing a large set of (possible new singularities of the $chi^{(n}$. We get the location of these singularities by solving the Landau conditions. We discuss the mathematical, as well as physical, interpretation of these new singularities. Among the singularities found, we underline the fact that the quadratic polynomial condition $1 + 3w + 4w^2 = 0$, that occurs in the linear differential equation of $chi^{(3}$, actually corresponds to the occurrence of complex multiplication for elliptic curves. The interpretation of complex multiplication for elliptic curves as complex fixed points of generators of the exact renormalization group is sketched. The other singularities occurring in our multiple integrals are not related to complex multiplication situations, suggesting a geometric interpretation in terms of more general (motivic mathematical structures beyond the theory of elliptic curves. The scaling limit of the (lattice

  8. Magnetization curves for non-elliptic cylindrical samples in a transverse field

    Indian Academy of Sciences (India)

    Debjani Karmakar; K V Bhagwat

    2001-01-01

    Using recent results for the surface current density on cylindrical surfaces of arbitrary cross-section producing uniform interior magnetic field and an assumed set of flux-fronts, solutions of Bean’s critical state model for cylindrical samples with non-elliptic cross-section are presented. Magnetization hysteresis loops for two cross-sections with different aspect ratios are obtained. A comparison with some exact results shows the limitations of this approach.

  9. High-resolution X-ray focusing concave (elliptical) curved crystal spectrograph for laser-produced plasma

    Institute of Scientific and Technical Information of China (English)

    Shali xiao(肖沙里); Yingjun Pan(潘英俊); Xianxin Zhong(钟先信); Xiancai Xiong(熊先才); Guohong Yang(杨国洪); Zongli Liu(刘宗礼); Yongkun Ding(丁永坤)

    2004-01-01

    The X-ray spectrum emitted from laser-produced plasma contains plentiful information.X-ray spectrometer is a powerful tool for plasma diagnosis and studying the information and evolution of the plasma.X-ray concave(elliptical)curved crystals analyzer was designed and manufactured to investigate the properties of laser-produced plasma.The experiment was carried out on Mianyang Xingguang-ⅡFacility and aimed at investigating the characteristics of a high density iron plasma.Experimental results using KAP,LIF,PET,and MICA curved crystal analyzers are described,and the spectra of Au,Ti laser-produced plasma are shown.The focusing crystal analyzer clearly gave an increase in sensitivity over a flat crystal.

  10. Fast Parallel Molecular Algorithms for DNA-Based Computation: Solving the Elliptic Curve Discrete Logarithm Problem over GF(2n

    Directory of Open Access Journals (Sweden)

    Kenli Li

    2008-01-01

    Full Text Available Elliptic curve cryptographic algorithms convert input data to unrecognizable encryption and the unrecognizable data back again into its original decrypted form. The security of this form of encryption hinges on the enormous difficulty that is required to solve the elliptic curve discrete logarithm problem (ECDLP, especially over GF(2n, n∈Z+. This paper describes an effective method to find solutions to the ECDLP by means of a molecular computer. We propose that this research accomplishment would represent a breakthrough for applied biological computation and this paper demonstrates that in principle this is possible. Three DNA-based algorithms: a parallel adder, a parallel multiplier, and a parallel inverse over GF(2n are described. The biological operation time of all of these algorithms is polynomial with respect to n. Considering this analysis, cryptography using a public key might be less secure. In this respect, a principal contribution of this paper is to provide enhanced evidence of the potential of molecular computing to tackle such ambitious computations.

  11. Elliptic curves and their torsion subgroups over number fields of type (2, 2,

    Institute of Scientific and Technical Information of China (English)

    QIU; Derong; ZHANG; Xianke

    2001-01-01

    [1]Shi Zhong-ci, On the accuracy of the quasi-conforming and generalize conforming finite elements, Chin. Ann. Math., 1990, 11B: 148.[2]Shi Zhong-ci, Chen Shao-chun, Huang Hong-ci, Plate elements with high accuracy, Collec. Geom. Anal. Math. Phys. (ed. Li Ta-Tsien), Singapore: World Scientific, 1997, 155—164.[3]Chen Shao-chun, Shi Zhong-ci, Double set parameter method for the construction of the element stiffness matrix, Mathematica Numerica Sinica (in Chinese), 1991, 13: 286.[4]Ciarlet, P., The Finite Element Method for Elliptic Problems, Amsterdam: North-Holland, 1978.

  12. Supporting Symmetric 128-bit AES in Networked Embedded Systems: An Elliptic Curve Key Establishment Protocol-on-Chip

    Directory of Open Access Journals (Sweden)

    Roshan Duraisamy

    2007-02-01

    Full Text Available The secure establishment of cryptographic keys for symmetric encryption via key agreement protocols enables nodes in a network of embedded systems and remote agents to communicate securely in an insecure environment. In this paper, we propose a pure hardware implementation of a key agreement protocol, which uses the elliptic curve Diffie-Hellmann and digital signature algorithms and enables two parties, a remote agent and a networked embedded system, to establish a 128-bit symmetric key for encryption of all transmitted data via the advanced encryption scheme (AES. The resulting implementation is a protocol-on-chip that supports full 128-bit equivalent security (PoC-128. The PoC-128 has been implemented in an FPGA, but it can also be used as an IP within different embedded applications. As 128-bit security is conjectured valid for the foreseeable future, the PoC-128 goes well beyond the state of art in securing networked embedded devices.

  13. Supporting Symmetric 128-bit AES in Networked Embedded Systems: An Elliptic Curve Key Establishment Protocol-on-Chip

    Directory of Open Access Journals (Sweden)

    Strangio MaurizioAdriano

    2007-01-01

    Full Text Available The secure establishment of cryptographic keys for symmetric encryption via key agreement protocols enables nodes in a network of embedded systems and remote agents to communicate securely in an insecure environment. In this paper, we propose a pure hardware implementation of a key agreement protocol, which uses the elliptic curve Diffie-Hellmann and digital signature algorithms and enables two parties, a remote agent and a networked embedded system, to establish a 128-bit symmetric key for encryption of all transmitted data via the advanced encryption scheme (AES. The resulting implementation is a protocol-on-chip that supports full 128-bit equivalent security (PoC-128. The PoC-128 has been implemented in an FPGA, but it can also be used as an IP within different embedded applications. As 128-bit security is conjectured valid for the foreseeable future, the PoC-128 goes well beyond the state of art in securing networked embedded devices.

  14. On Fibonacci Numbers Which Are Elliptic Carmichael

    Science.gov (United States)

    2014-12-27

    On Fibonacci numbers which are elliptic Carmichael Florian Luca School of Mathematics University of the Witwatersrand P. O. Box Wits 2050, South...CM elliptic curve with CM field different from Q( √ −1), then the set of n for which the nth Fibonacci number Fn is elliptic Carmichael for E is of...number. 1. REPORT DATE 27 DEC 2014 2. REPORT TYPE 3. DATES COVERED 00-00-2014 to 00-00-2014 4. TITLE AND SUBTITLE On Fibonacci Numbers Which Are

  15. On Fibonacci Numbers Which Are Elliptic Korselt Numbers

    Science.gov (United States)

    2014-11-17

    On Fibonacci numbers which are elliptic Korselt numbers Florian Luca School of Mathematics University of the Witwatersrand P. O. Box Wits 2050, South...is a CM elliptic curve with CM field Q( √ −d), then the set of n for which the nth Fibonacci number Fn satisfies an elliptic Korselt criterion for Q...SUBTITLE On Fibonacci Numbers Which Are Elliptic Korselt Numbers 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) 5d

  16. HIERARCHICAL ACCESS CONTROL IN DYNAMIC PEER GROUPS USING SYMMETRIC POLYNOMIAL AND TREE BASED GROUP ELLIPTIC CURVE DIFFIE HELLMAN SCHEME

    Directory of Open Access Journals (Sweden)

    Nafeesa Begum Jeddy

    2014-01-01

    Full Text Available Hierarchical Access Control in group communication is an active area of research which is difficult to achieve it. Its primary objective is to allow users of a higher authority group to access information or resource held by lower group users and preventing the lower group users to access information held by higher class users. Large collection of collaborative applications in organizations inherently has hierarchical structures for functioning, where providing security by efficient group key management is a big challenging issue. While preserving centralized methods for hierarchical access control, it is difficult to achieve efficiency as a single membership change will result in lot of changes which are difficult to maintain. So, using distributed key agreement techniques is more appropriate for this scenario. This study explore on novel group key agreement approach, which combines both the symmetric polynomial scheme and Tree Based Group elliptic Curve key exchange. Also, it yields a secure protocol suite that is good in fault-tolerant and simple. The efficiency of SP-TGECDH is better than many other schemes. Using TGECDH makes the scheme suitable small Low powered devices.

  17. An improved three party authenticated key exchange protocol using hash function and elliptic curve cryptography for mobile-commerce environments

    Directory of Open Access Journals (Sweden)

    S.K. Hafizul Islam

    2017-07-01

    Full Text Available In the literature, many three-party authenticated key exchange (3PAKE protocols are put forwarded to established a secure session key between two users with the help of trusted server. The computed session key will ensure secure message exchange between the users over any insecure communication networks. In this paper, we identified some deficiencies in Tan’s 3PAKE protocol and then devised an improved 3PAKE protocol without symmetric key en/decryption technique for mobile-commerce environments. The proposed protocol is based on the elliptic curve cryptography and one-way cryptographic hash function. In order to prove security validation of the proposed 3PAKE protocol we have used widely accepted AVISPA software whose results confirm that the proposed protocol is secure against active and passive attacks including replay and man-in-the-middle attacks. The proposed protocol is not only secure in the AVISPA software, but it also secure against relevant numerous security attacks such as man-in-the-middle attack, impersonation attack, parallel attack, key-compromise impersonation attack, etc. In addition, our protocol is designed with lower computation cost than other relevant protocols. Therefore, the proposed protocol is more efficient and suitable for practical use than other protocols in mobile-commerce environments.

  18. An Enhanced Biometric Based Authentication with Key-Agreement Protocol for Multi-Server Architecture Based on Elliptic Curve Cryptography.

    Science.gov (United States)

    Reddy, Alavalapati Goutham; Das, Ashok Kumar; Odelu, Vanga; Yoo, Kee-Young

    2016-01-01

    Biometric based authentication protocols for multi-server architectures have gained momentum in recent times due to advancements in wireless technologies and associated constraints. Lu et al. recently proposed a robust biometric based authentication with key agreement protocol for a multi-server environment using smart cards. They claimed that their protocol is efficient and resistant to prominent security attacks. The careful investigation of this paper proves that Lu et al.'s protocol does not provide user anonymity, perfect forward secrecy and is susceptible to server and user impersonation attacks, man-in-middle attacks and clock synchronization problems. In addition, this paper proposes an enhanced biometric based authentication with key-agreement protocol for multi-server architecture based on elliptic curve cryptography using smartcards. We proved that the proposed protocol achieves mutual authentication using Burrows-Abadi-Needham (BAN) logic. The formal security of the proposed protocol is verified using the AVISPA (Automated Validation of Internet Security Protocols and Applications) tool to show that our protocol can withstand active and passive attacks. The formal and informal security analyses and performance analysis demonstrates that the proposed protocol is robust and efficient compared to Lu et al.'s protocol and existing similar protocols.

  19. An Enhanced Biometric Based Authentication with Key-Agreement Protocol for Multi-Server Architecture Based on Elliptic Curve Cryptography.

    Directory of Open Access Journals (Sweden)

    Alavalapati Goutham Reddy

    Full Text Available Biometric based authentication protocols for multi-server architectures have gained momentum in recent times due to advancements in wireless technologies and associated constraints. Lu et al. recently proposed a robust biometric based authentication with key agreement protocol for a multi-server environment using smart cards. They claimed that their protocol is efficient and resistant to prominent security attacks. The careful investigation of this paper proves that Lu et al.'s protocol does not provide user anonymity, perfect forward secrecy and is susceptible to server and user impersonation attacks, man-in-middle attacks and clock synchronization problems. In addition, this paper proposes an enhanced biometric based authentication with key-agreement protocol for multi-server architecture based on elliptic curve cryptography using smartcards. We proved that the proposed protocol achieves mutual authentication using Burrows-Abadi-Needham (BAN logic. The formal security of the proposed protocol is verified using the AVISPA (Automated Validation of Internet Security Protocols and Applications tool to show that our protocol can withstand active and passive attacks. The formal and informal security analyses and performance analysis demonstrates that the proposed protocol is robust and efficient compared to Lu et al.'s protocol and existing similar protocols.

  20. Vector Bundles over Elliptic Fibrations

    CERN Document Server

    Friedman, R; Witten, Edward; Friedman, Robert; Morgan, John W.; Witten, Edward

    1997-01-01

    This paper gives various methods for constructing vector bundles over elliptic curves and more generally over families of elliptic curves. We construct universal families over generalized elliptic curves via spectral cover methods and also by extensions, and then give a relative version of the construction in families. We give various examples and make Chern class computations.

  1. A new two-round dynamic authenticated contributory group key agreement protocol using elliptic curve Diffie–Hellman with privacy preserving public key infrastructure

    Indian Academy of Sciences (India)

    Vankamamidi S Naresh; Nistala V E S Murthy

    2015-10-01

    In this paper a new two-round authenticated contributory group key agreement based on Elliptic Curve Diffie–Hellman protocol with Privacy Preserving Public Key Infrastructure (PP-PKI) is introduced and is extended to a dynamic authenticated contributory group key agreement with join and leave protocols for dynamic groups. The proposed protocol provides such security attributes as forward secrecy, backward secrecy, and defense against man in the middle (MITM) and Unknown keyshare security attacks and also authentication along with privacy preserving attributes like anonymity, traceability and unlinkability. In the end, they are compared with other popular Diffie–Hellman and Elliptic Curve Diffie–Hellman based group key agreement protocols and the results are found to be satisfactory.

  2. Geometry of Higgs bundles over elliptic curves related to automorphisms of simple Lie algebras, Calogero-Moser systems, and KZB equations

    Science.gov (United States)

    Levin, A. M.; Olshanetsky, M. A.; Zotov, A. V.

    2016-08-01

    We construct twisted Calogero-Moser systems with spins as Hitchin systems derived from the Higgs bundles over elliptic curves, where the transition operators are defined by arbitrary finite-order automorphisms of the underlying Lie algebras. We thus obtain a spin generalization of the twisted D'Hoker-Phong and Bordner-Corrigan-Sasaki-Takasaki systems. In addition, we construct the corresponding twisted classical dynamical r-matrices and the Knizhnik-Zamolodchikov-Bernard equations related to the automorphisms of Lie algebras.

  3. Extending the IEEE 802.15.4 Security Suite with a Compact Implementation of the NIST P-192/B-163 Elliptic Curves

    Directory of Open Access Journals (Sweden)

    Abdellah Touhafi

    2013-07-01

    Full Text Available Typically, commercial sensor nodes are equipped with MCUsclocked at a low-frequency (i.e., within the 4–12 MHz range. Consequently, executing cryptographic algorithms in those MCUs generally requires a huge amount of time. In this respect, the required energy consumption can be higher than using a separate accelerator based on a Field-programmable Gate Array (FPGA that is switched on when needed. In this manuscript, we present the design of a cryptographic accelerator suitable for an FPGA-based sensor node and compliant with the IEEE802.15.4 standard. All the embedded resources of the target platform (Xilinx Artix-7 have been maximized in order to provide a cost-effective solution. Moreover, we have added key negotiation capabilities to the IEEE 802.15.4 security suite based on Elliptic Curve Cryptography (ECC. Our results suggest that tailored accelerators based on FPGA can behave better in terms of energy than contemporary software solutions for motes, such as the TinyECC and NanoECC libraries. In this regard, a point multiplication (PM can be performed between 8.58- and 15.4-times faster, 3.40- to 23.59-times faster (Elliptic Curve Diffie-Hellman, ECDH and between 5.45- and 34.26-times faster (Elliptic Curve Integrated Encryption Scheme, ECIES. Moreover, the energy consumption was also improved with a factor of 8.96 (PM.

  4. Extending the IEEE 802.15.4 security suite with a compact implementation of the NIST P-192/B-163 elliptic curves.

    Science.gov (United States)

    de la Piedra, Antonio; Braeken, An; Touhafi, Abdellah

    2013-07-29

    Typically, commercial sensor nodes are equipped with MCUsclocked at a low-frequency (i.e., within the 4-12 MHz range). Consequently, executing cryptographic algorithms in those MCUs generally requires a huge amount of time. In this respect, the required energy consumption can be higher than using a separate accelerator based on a Field-programmable Gate Array (FPGA) that is switched on when needed. In this manuscript, we present the design of a cryptographic accelerator suitable for an FPGA-based sensor node and compliant with the IEEE802.15.4 standard. All the embedded resources of the target platform (Xilinx Artix-7) have been maximized in order to provide a cost-effective solution. Moreover, we have added key negotiation capabilities to the IEEE 802.15.4 security suite based on Elliptic Curve Cryptography (ECC). Our results suggest that tailored accelerators based on FPGA can behave better in terms of energy than contemporary software solutions for motes, such as the TinyECC and NanoECC libraries. In this regard, a point multiplication (PM) can be performed between 8.58- and 15.4-times faster, 3.40- to 23.59-times faster (Elliptic Curve Diffie-Hellman, ECDH) and between 5.45- and 34.26-times faster (Elliptic Curve Integrated Encryption Scheme, ECIES). Moreover, the energy consumption was also improved with a factor of 8.96 (PM).

  5. 基于FPGA的椭圆曲线密码(ECC)算法硬件设计%Hardware Design of Elliptic Curve Cryptography(ECC) Based on FPGA

    Institute of Scientific and Technical Information of China (English)

    赵曼; 徐和根

    2013-01-01

    Elliptic curve cryptosystem ( ECC) is a public key encryption system with the most secure unit key security at present, the application of FPGA and hardware design to implement the ECC cryptography have become a concern in the field of information security. The further study of the elliptic curve encryption and decryption is based on the theory, using the verilog hardware description language and schematic design method to achieve the ECC encryption algorithm, with high-speed and low-power characteristics.%椭圆曲线密码体制(elliptic curve cryptosystem,ECC)是目前已知的单位密钥安全性最高的一种公钥加密体制,使用FPGA等硬件设计方法来实现ECC密码系统已成为信息安全领域引人关注的研究.该文在深入研究椭圆曲线加解密理论基础上,使用Verilog硬件描述语言和原理图输入法共同实现了ECC加密算法,具有高速、低功耗的特点.

  6. Elliptic Carmichael Numbers and Elliptic Korselt Criteria

    CERN Document Server

    Silverman, Joseph H

    2011-01-01

    Let E/Q be an elliptic curve, let L(E,s)=\\sum a_n/n^s be the L-series of E/Q, and let P be a point in E(Q). An integer n > 2 having at least two distinct prime factors will be be called an elliptic pseudoprime for (E,P) if E has good reduction at all primes dividing n and (n+1-a_n)P = 0 (mod n). Then n is an elliptic Carmichael number for E if n is an elliptic pseudoprime for every P in E(Z/nZ). In this note we describe two elliptic analogues of Korselt's criterion for Carmichael numbers, and we analyze elliptic Carmichael numbers of the form pq.

  7. Elliptic algebras

    Energy Technology Data Exchange (ETDEWEB)

    Odesskii, A V [L.D. Landau Institute for Theoretical Physics, Russian Academy of Sciences, Moscow (Russian Federation)

    2002-12-31

    This survey is devoted to associative Z{sub {>=}}{sub 0}-graded algebras presented by n generators and n(n-1)/2 quadratic relations and satisfying the so-called Poincare-Birkhoff-Witt condition (PBW-algebras). Examples are considered of such algebras, depending on two continuous parameters (namely, on an elliptic curve and a point on it), that are flat deformations of the polynomial ring in n variables. Diverse properties of these algebras are described, together with their relations to integrable systems, deformation quantization, moduli spaces, and other directions of modern investigations.

  8. Comparison of Hanna and Hessburg-Barron trephine and punch systems using histological, anterior segment optical coherence tomography, and elliptical curve fitting models.

    Science.gov (United States)

    Moshirfar, Majid; Calvo, Charles M; Kinard, Krista I; Williams, Lloyd B; Sikder, Shameema; Neuffer, Marcus C

    2011-01-01

    This study analyzes the characteristics of donor and recipient tissue preparation between the Hessburg-Barron and Hanna punch and trephine systems by using elliptical curve fitting models, light microscopy, and anterior segment optical coherence tomography (AS-OCT). Eight millimeter Hessburg-Barron and Hanna vacuum trephines and punches were used on six cadaver globes and six corneal-scleral rims, respectively. Eccentricity data were generated using measurements from photographs of the corneal buttons and were used to generate an elliptical curve fit to calculate properties of the corneal button. The trephination angle and punch angle were measured by digital protractor software from light microscopy and AS-OCT images to evaluate the consistency with which each device cuts the cornea. The Hanna trephine showed a trend towards producing a more circular recipient button than the Barron trephine (ratio of major axis to minor axis), ie, 1.059 ± 0.041 versus 1.110 ± 0.027 (P = 0.147) and the Hanna punch showed a trend towards producing a more circular donor cut than the Barron punch, ie, 1.021 ± 0.022 versus 1.046 ± 0.039 (P = 0.445). The Hanna trephine was demonstrated to have a more consistent trephination angle than the Barron trephine when assessing light microscopy images, ie, ±14.39° (95% confidence interval [CI] 111.9-157.7) versus ±19.38° (95% CI 101.9-150.2, P = 0.492) and OCT images, ie, ±8.08° (95% CI 106.2-123.3) versus ±11.16° (95% CI 109.3-132.6, P = 0.306). The angle created by the Hanna punch had less variability than the Barron punch from both the light microscopy, ie, ±4.81° (95% CI 101.6-113.9) versus ±11.28° (95% CI 84.5-120.6, P = 0.295) and AS-OCT imaging, ie, ±9.96° (95% CI 95.7-116.4) versus ±14.02° (95% CI 91.8-123.7, P = 0.825). Statistical significance was not achieved. The Hanna trephine and punch may be more accurate and consistent in cutting corneal buttons than the Hessburg-Barron trephine and punch when evaluated using

  9. Comparison of Hanna and Hessburg-Barron trephine and punch systems using histological, anterior segment optical coherence tomography, and elliptical curve fitting models

    Science.gov (United States)

    Moshirfar, Majid; Calvo, Charles M; Kinard, Krista I; Williams, Lloyd B; Sikder, Shameema; Neuffer, Marcus C

    2011-01-01

    Background: This study analyzes the characteristics of donor and recipient tissue preparation between the Hessburg-Barron and Hanna punch and trephine systems by using elliptical curve fitting models, light microscopy, and anterior segment optical coherence tomography (AS-OCT). Methods: Eight millimeter Hessburg-Barron and Hanna vacuum trephines and punches were used on six cadaver globes and six corneal-scleral rims, respectively. Eccentricity data were generated using measurements from photographs of the corneal buttons and were used to generate an elliptical curve fit to calculate properties of the corneal button. The trephination angle and punch angle were measured by digital protractor software from light microscopy and AS-OCT images to evaluate the consistency with which each device cuts the cornea. Results: The Hanna trephine showed a trend towards producing a more circular recipient button than the Barron trephine (ratio of major axis to minor axis), ie, 1.059 ± 0.041 versus 1.110 ± 0.027 (P = 0.147) and the Hanna punch showed a trend towards producing a more circular donor cut than the Barron punch, ie, 1.021 ± 0.022 versus 1.046 ± 0.039 (P = 0.445). The Hanna trephine was demonstrated to have a more consistent trephination angle than the Barron trephine when assessing light microscopy images, ie, ±14.39° (95% confidence interval [CI] 111.9–157.7) versus ±19.38° (95% CI 101.9–150.2, P = 0.492) and OCT images, ie, ±8.08° (95% CI 106.2–123.3) versus ±11.16° (95% CI 109.3–132.6, P = 0.306). The angle created by the Hanna punch had less variability than the Barron punch from both the light microscopy, ie, ±4.81° (95% CI 101.6–113.9) versus ±11.28° (95% CI 84.5–120.6, P = 0.295) and AS-OCT imaging, ie, ±9.96° (95% CI 95.7–116.4) versus ±14.02° (95% CI 91.8–123.7, P = 0.825). Statistical significance was not achieved. Conclusion: The Hanna trephine and punch may be more accurate and consistent in cutting corneal buttons than

  10. Application of Elliptic Curve Cryptography in CA Mobile Payment%椭圆曲线密码在移动支付CA中的应用

    Institute of Scientific and Technical Information of China (English)

    王艳红; 袁春花

    2014-01-01

    The mobile payment based on mobile phone or some other mobile terminals brings people convenience, but its security is-sues are also increasingly prominent. By exploring the structure of mobile payment system and the elliptic curve cryptography system, in view of the security problems of the mobile payment system, this paper designs a CA trust model in the mobile payment system, after analyzing the model, the ellipse curve algorithm is applied to it, ensuring the security of the mobile payment system.%基于手机等移动终端的移动支付在带给大家快捷方便的同时,移动支付的安全性问题也日益突出。通过探讨移动支付系统结构以及椭圆曲线密码系统,针对移动支付系统存在的安全问题,设计了移动支付系统中一种CA的信任模型,对该模型分析之后,将椭圆曲线算法应用到其中,保证了移动支付系统的安全。

  11. Comparison of Hanna and Hessburg-Barron trephine and punch systems using histological, anterior segment optical coherence tomography, and elliptical curve fitting models

    Directory of Open Access Journals (Sweden)

    Moshirfar M

    2011-08-01

    Full Text Available Majid Moshirfar1, Charles M Calvo2, Krista I Kinard1, Lloyd B Williams1, Shameema Sikder3, Marcus C Neuffer11University of Utah, Department of Ophthalmology and Visual Sciences, Salt Lake City, UT, USA; 2University of Nevada, School of Medicine, Las Vegas, NV, USA; 3Wilmer Eye Institute, Johns Hopkins University, Baltimore, MD, USABackground: This study analyzes the characteristics of donor and recipient tissue preparation between the Hessburg-Barron and Hanna punch and trephine systems by using elliptical curve fitting models, light microscopy, and anterior segment optical coherence tomography (AS-OCT.Methods: Eight millimeter Hessburg-Barron and Hanna vacuum trephines and punches were used on six cadaver globes and six corneal-scleral rims, respectively. Eccentricity data were generated using measurements from photographs of the corneal buttons and were used to generate an elliptical curve fit to calculate properties of the corneal button. The trephination angle and punch angle were measured by digital protractor software from light microscopy and AS-OCT images to evaluate the consistency with which each device cuts the cornea.Results: The Hanna trephine showed a trend towards producing a more circular recipient button than the Barron trephine (ratio of major axis to minor axis, ie, 1.059 ± 0.041 versus 1.110 ± 0.027 (P = 0.147 and the Hanna punch showed a trend towards producing a more circular donor cut than the Barron punch, ie, 1.021 ± 0.022 versus 1.046 ± 0.039 (P = 0.445. The Hanna trephine was demonstrated to have a more consistent trephination angle than the Barron trephine when assessing light microscopy images, ie, ±14.39° (95% confidence interval [CI] 111.9–157.7 versus ±19.38° (95% CI 101.9–150.2, P = 0.492 and OCT images, ie, ± 8.08° (95% CI 106.2–123.3 versus ± 11.16° (95% CI 109.3–132.6, P = 0.306. The angle created by the Hanna punch had less variability than the Barron punch from both the light microscopy

  12. Provably Secure Signcryption Scheme Based on Elliptic Curve%基于椭圆曲线的可证明安全的签密方案

    Institute of Scientific and Technical Information of China (English)

    任艳丽; 陆梅宁

    2011-01-01

    A signcryption scheme can realize signature and encryption simultaneously, and its cost is smaller than the sum of signature and encryption. However, most signcryption schemes do not have strict security proof. This paper proposes a signcryption scheme based on difficult problems of elliptic curve group. The scheme is efficient and only needs one pair operation. It proves that the scheme is semantic secure and unforgeable in the standard model. Moreover, the scheme has non-repudiation, forward security and public verification.%签密方案可以同时实现保密和认证,且实现代价小于加密和签名之和,但大多数签密方案都没有严格的安全证明.为此,基于椭圆曲线群上的困难问题提出一个可证明安全的签密方案.方案仅需要一次双线性对运算,实现快速.在标准模型下,证明该方案既具有密文不可区分性与签名不可伪造性,也具有不可否认性、前向安全性和公开可验证性.

  13. An algorithm based on elliptic interpolation for generating random curves%一种基于椭圆插值的随机曲线生成算法

    Institute of Scientific and Technical Information of China (English)

    李玲; 魏玮

    2012-01-01

    在计算机图形学中,建立复杂的结构或形状的模型是一个核心问题.随机曲线的生成在计算机游戏,电影,建筑模型,城市规划和虚拟现实等领域中,也扮演着十分重要的角色.本文主要研究二值图像中随机产生曲线的算法,算法首先采用随机的方法产生初始点和终结点,再利用椭圆内随机插值的方法产生插值点,以新产生的点和其相邻点做为初始点与终结点,再利用椭圆内随机插值的方法产生新的插值点,依此类推最后得到由诸多插值点组成的整条曲线.该过程中为了保证曲线收敛,假设先产生的插值点对曲线的形成趋势影响大,后产生的随机点对曲线的形成趋势影响小.并且,在插值过程中,只对相邻插值点进行下一步插值.结合椭圆内产生的随机曲线的过程,使用Visual C++软件来实现随机曲线的生成算法并进行结果的详细分析,同时做相应的说明和结论来改善用户交互系统.%The building of geometric models with complex shapes and structures is one of the key issues in computer graphics. Random curves also play important roles in many domains such as computer games, movies, architectural models, urban planning, virtual reality etc. In this paper, we present a novel synthesis algorithm for procedurally generating random curves in binary image. The first step is to generate the starting point and ending point randomly; The second step is to generate the interpolative point by using the elliptic interpolation method; The third step is to generate the next new interpolative point by starting with the new point and ending with its adjacent point. These new points though quite few, finally constitute the whole curve. To ensure the convergence of the curve, we firstly assume that the earlier interpolative points have more impact on the trend of the curve, while the latter points has less impact. The second assumption is to generate new points only between the

  14. Elliptic Curve Cryptography with Java

    Science.gov (United States)

    Klima, Richard E.; Sigmon, Neil P.

    2005-01-01

    The use of the computer, and specifically the mathematics software package Maple, has played a central role in the authors' abstract algebra course because it provides their students with a way to see realistic examples of the topics they discuss without having to struggle with extensive computations. However, Maple does not provide the computer…

  15. Degenerating the elliptic Schlesinger system

    Science.gov (United States)

    Aminov, G. A.; Artamonov, S. B.

    2013-01-01

    We study various ways of degenerating the Schlesinger system on the elliptic curve with R marked points. We construct a limit procedure based on an infinite shift of the elliptic curve parameter and on shifts of the marked points. We show that using this procedure allows obtaining a nonautonomous Hamiltonian system describing the Toda chain with additional spin sl(N, ℂ) degrees of freedom.

  16. On the rank of elliptic curves over $\\mathbf{Q}(\\sqrt{-3})$ with torsion groups $\\mathbf{Z}/3\\mathbf{Z} \\times \\mathbf{Z}/3\\mathbf{Z}$ and $\\mathbf{Z}/3\\mathbf{Z} \\times \\mathbf{Z}/6\\mathbf{Z}$

    OpenAIRE

    2011-01-01

    We construct elliptic curves over the field $\\mathbf{Q}(\\sqrt{-3})$ with torsion group $\\mathbf{Z}/3\\mathbf{Z} \\times \\mathbf{Z}/3\\mathbf{Z}$ and ranks equal to 7 and an elliptic curve over the same field with torsion group $\\mathbf{Z}/3\\mathbf{Z} \\times \\mathbf{Z}/6\\mathbf{Z}$ and rank equal to 6.

  17. Elliptic scattering equations

    Energy Technology Data Exchange (ETDEWEB)

    Cardona, Carlos [Physics Division, National Center for Theoretical Sciences, National Tsing-Hua University,Hsinchu, Taiwan 30013 (China); Gomez, Humberto [Instituto de Fisica - Universidade de São Paulo,Caixa Postal 66318, 05315-970 São Paulo, SP (Brazil); Facultad de Ciencias Basicas, Universidad Santiago de Cali,Calle 5 62-00 Barrio Pampalinda, Cali, Valle (Colombia)

    2016-06-16

    Recently the CHY approach has been extended to one loop level using elliptic functions and modular forms over a Jacobian variety. Due to the difficulty in manipulating these kind of functions, we propose an alternative prescription that is totally algebraic. This new proposal is based on an elliptic algebraic curve embedded in a ℂP{sup 2} space. We show that for the simplest integrand, namely the n−gon, our proposal indeed reproduces the expected result. By using the recently formulated Λ−algorithm, we found a novel recurrence relation expansion in terms of tree level off-shell amplitudes. Our results connect nicely with recent results on the one-loop formulation of the scattering equations. In addition, this new proposal can be easily stretched out to hyperelliptic curves in order to compute higher genus.

  18. Dynamical Masses of Elliptical Galaxies

    CERN Document Server

    Gerhard, O E

    2002-01-01

    Recent progress in the dynamical analysis of elliptical galaxy kinematics is reviewed. Results reported briefly include (i) the surprisingly uniform anisotropy structure of luminous ellipticals, (ii) their nearly flat (to $\\sim 2R_e$) circular velocity curves, (iii) the Tully-Fisher and $M/L - L$ relations and the connection to the Fundamental Plane, and (iv) the large halo mass densities implied by the dynamical models.

  19. 椭圆曲线 y2= px(x2-2)的整数点%The Integral Points on the Elliptic Curve y2 =px(x2-2)

    Institute of Scientific and Technical Information of China (English)

    赵晶晶

    2016-01-01

    Let p be a positive prime such that p is square free.We proved that if every prime divisor q of p satis fies q≡3(mod8),then the elliptic curve in title has no positive integer points;if every prime divi-sor q of p satisfies q≡5(mod 8),then the elliptic curve in title has at most two positive integer points.%设 p 是大于1的无平方因子的正奇数。证明了如果 p 的素因素 q 都满足 q≡3(mod 8),则椭圆曲线 y2= px(x2-2)无正整数点;如果 p 的素因素 p 都满足 q≡5(mod 8),则椭圆曲线 y2=px(x2-2)至多有2组正整数点。

  20. Spatial curved beam model and mechanical analysis of elliptical spiral stairs%椭圆旋转楼梯的空间曲梁模型与内力分析

    Institute of Scientific and Technical Information of China (English)

    周平槐; 张群力; 杨学林

    2012-01-01

    建筑中经常出现曲线型旋转楼梯,其内力分析较为复杂,国内少见这种楼梯的计算理论。结合实际工程,利用微分几何等数学方法,建立了椭圆旋转楼梯中心线为椭圆螺旋线、楼梯内外边线则为中心线主法矢上的等距线的数学模型的空间曲梁模型。基于楼梯的曲梁简化计算模型,同时选用了接近于实际作用的荷载等效作用曲线,推导出在单位力和均布荷载作用下梯梁上任一点的内力计算公式,并与有限元分析结果作了比较。分析表明,空间曲梁模型能较好地描述椭圆旋转楼梯的几何性质,公式推导和有限元分析所得的内力十分接近。其他旋转形式的楼梯,也可参考上述方法建立与其形状一致的数学模型以及内力分析,为设计提供依据。%There are many curve spiral stairs which inner forces are hard to analyze in buildings, and theories and methods of these stairs are rare domestically. Under the background of the project, the spatial curve beam differential model is established by mathematical method such as differential geometry and so on, which the center curve as elliptical helix, and the inside and outside edges as offset curves on the main normal vector of the center curve. The curve beam is modeled simply. After the equal load-curve is adopted, calculation formulas of inner forces under unit load and under vertical uniform load are obtained. Compared with the results of finite element methods ( FEM ) , it shows that mathematical modeling is in agreement with elliptical spiral stairs, the inner forces from formulations and FEM are similar. It can be reference for spiral stairs to establish the mathematical model and then analyze inner forces for design these stairs.

  1. 基于椭圆曲线的云存储数据完整性的验证研究%Validation of cloud storage data integrity based on elliptic curve

    Institute of Scientific and Technical Information of China (English)

    陈志忠

    2016-01-01

    Since the commonly⁃used cloud storage data integrity verification scheme can′t meet the requirement of data vali⁃dation,the cloud storage data integrity verification scheme ECPDP based on elliptic curve is put forward. The elliptic curve schemes of cloud storage data integrity verification with two⁃party participation,three⁃party participation and dynamic verifica⁃tion were designed respectively. And then the performance comparison experiments for the traditional PDP and ECPDP cloud storage data integrity verification schemes were performed based on OpenSSL code library. The experimental results show that the ECPDP scheme is better than the traditional PDP scheme in the aspects of protocol pretreatment performance,verification performance and challenge performance,and has high protocol safety.%针对当前常用的云存储数据完整性验证方案已无法适应数据验证需要的问题,提出了基于椭圆曲线的云存储数据完整性验证方案ECPDP,分别设计了二方参与、三方参与和动态验证的云存储数据验证的椭圆曲线方案。然后基于OpenSSL密码库对传统PDP和ECPDP云存储数据完整性验证方案进行了性能对比实验,实验结果表明,ECPDP方案在协议的预处理性能、验证性能及挑战性能方面均较传统的PDP协议有所提高,且不降低协议的安全性。

  2. Split-CM points and central values of Hecke L-series

    CERN Document Server

    Hopkins, Kimberly

    2010-01-01

    Split-CM points are points of the moduli space h_2/Sp_4(Z) corresponding to products $E \\times E'$ of elliptic curves with the same complex multiplication. We prove that the number of split-CM points in a given class of h_2/Sp_4(Z) is related to the coefficients of a weight 3/2 modular form studied by Eichler. The main application of this result is a formula for the central value $L(\\psi_N, 1)$ of a certain Hecke L-series. The Hecke character $\\psi_N$ is a twist of the canonical Hecke character $\\psi$ for the elliptic Q-curve A studied by Gross, and formulas for $L(\\psi, 1)$ as well as generalizations were proven by Villegas and Zagier. The formulas for $L(\\psin, 1)$ are easily computable and numerical examples are given.

  3. Elliptic and magneto-elliptic instabilities

    Directory of Open Access Journals (Sweden)

    Lyra Wladimir

    2013-04-01

    Full Text Available Vortices are the fundamental units of turbulent flow. Understanding their stability properties therefore provides fundamental insights on the nature of turbulence itself. In this contribution I briely review the phenomenological aspects of the instability of elliptic streamlines, in the hydro (elliptic instability and hydromagnetic (magneto-elliptic instability regimes. Vortex survival in disks is a balance between vortex destruction by these mechanisms, and vortex production by others, namely, the Rossby wave instability and the baroclinic instability.

  4. Chaotic properties of the elliptical stadium

    CERN Document Server

    Markarian, R K; De Pinto-Carvalho, S; Markarian, Roberto; Kamphorst, Sylvie Oliffson; de Carvalho, Sonia Pinto

    1995-01-01

    The elliptical stadium is a curve constructed by joining two half-ellipses, with half axes a>1 and b=1, by two straight segments of equal length 2h. In this work we find bounds on h, for a close to 1, to assure the positiveness of a Lyapunov exponent. We conclude that, for these values of a and h, the elliptical stadium billiard mapping is ergodic and has the K-property.

  5. A Study of Hyperelliptic Curves in Cryptography

    Directory of Open Access Journals (Sweden)

    Reza Alimoradi

    2016-08-01

    Full Text Available Elliptic curves are some specific type of curves known as hyper elliptic curves. Compared to the integer factorization problem(IFP based systems, using elliptic curve based cryptography will significantly decrease key size of the encryption. Therefore, application of this type of cryptography in systems that need high security and smaller key size has found great attention. Hyperelliptic curves help to make key length shorter. Many investigations are done with regard to improving computations, hardware and software implementation of these curves, their security and resistance against attacks. This paper studies and analyzes researches done about security and efficiency of hyperelliptic curves.

  6. Random Matrix Theory and Elliptic Curves

    Science.gov (United States)

    2014-11-24

    the Riemann zeta-function higher up than ever previously reached – so the support led to a new world-record for the verification of the Riemann...frequency of vanishing of quadratic twists of modular L-functions, In Number Theory for the Millennium I: Proceedings of the Millennial Conference on

  7. Elliptic Curve Blind Digital Signature Schemes

    Institute of Scientific and Technical Information of China (English)

    YOULin; YANGYixian; WENQiaoyan

    2003-01-01

    Blind signature schemes are important cryptographic protocols in guaranteeing the privacy or anonymity of the users.Three new blind signature schemes and their corresponding generalizations are pro-posed. Moreover, their securities are simply analyzed.

  8. Manin Matrices, Quantum Elliptic Commutative Families and Characteristic Polynomial of Elliptic Gaudin Model

    Directory of Open Access Journals (Sweden)

    Dmitri Talalaev

    2009-12-01

    Full Text Available In this paper we construct the quantum spectral curve for the quantum dynamical elliptic gl_n Gaudin model. We realize it considering a commutative family corresponding to the Felder's elliptic quantum group E_{τ,h}(gl_n and taking the appropriate limit. The approach of Manin matrices here suits well to the problem of constructing the generation function of commuting elements which plays an important role in SoV and Langlands concept.

  9. Manin Matrices, Quantum Elliptic Commutative Families and Characteristic Polynomial of Elliptic Gaudin model

    CERN Document Server

    Rubtsov, V; Talalaev, D

    2009-01-01

    In this paper we construct the quantum spectral curve for the quantum dynamical elliptic gl(n) Gaudin model. We realize it considering a commutative family corresponding to the Felder's elliptic quantum group and taking the appropriate limit. The approach of Manin matrices here suits well to the problem of constructing the generation function of commuting elements which plays an important role in SoV and Langlands concept.

  10. ECM using Edwards curves

    DEFF Research Database (Denmark)

    Bernstein, Daniel J.; Birkner, Peter; Lange, Tanja;

    2013-01-01

    This paper introduces EECM-MPFQ, a fast implementation of the elliptic-curve method of factoring integers. EECM-MPFQ uses fewer modular multiplications than the well-known GMP-ECM software, takes less time than GMP-ECM, and finds more primes than GMP-ECM. The main improvements above the modular......-arithmetic level are as follows: (1) use Edwards curves instead of Montgomery curves; (2) use extended Edwards coordinates; (3) use signed-sliding-window addition-subtraction chains; (4) batch primes to increase the window size; (5) choose curves with small parameters and base points; (6) choose curves with large...

  11. Efficacy of CM-Wire, M-Wire, and Nickel-Titanium Instruments for Removing Filling Material from Curved Root Canals: A Micro-Computed Tomography Study.

    Science.gov (United States)

    Rodrigues, Clarissa Teles; Duarte, Marco Antonio Hungaro; de Almeida, Marcela Milanezi; de Andrade, Flaviana Bombarda; Bernardineli, Norberti

    2016-11-01

    The aim of this ex vivo study was to evaluate the removal of filling material after using CM-wire, M-wire, and nickel-titanium instruments in both reciprocating and rotary motions in curved canals. Thirty maxillary lateral incisors were divided into 9 groups according to retreatment procedures: Reciproc R25 followed by Mtwo 40/.04 and ProDesign Logic 50/.01 files; ProDesign R 25/.06 followed by ProDesign Logic 40/.05 and ProDesign Logic 50/.01 files; and Gates-Glidden drills, Hedström files, and K-files up to apical size 30 followed by K-file 40 and K-file 50 up to the working length. Micro-computed tomography scans were performed before and after each reinstrumentation procedure to evaluate root canal filling removal. Statistical analysis was performed with Kruskal-Wallis, Friedman, and Wilcoxon tests (P material removal were found in the 3 groups of teeth. The use of Mtwo and ProDesign Logic 40/.05 rotary files did not enhance filling material removal after the use of reciprocating files. The use of ProDesign Logic 50/.01 files significantly reduced the amount of filling material at the apical levels compared with the use of reciprocating files. Association of reciprocating and rotary files was capable of removing a large amount of filling material in the retreatment of curved canals, irrespective of the type of alloy of the instruments. The use of a ProDesign Logic 50/.01 file for apical preparation significantly reduced the amount of remnant material in the apical portion when compared with reciprocating instruments. Copyright © 2016 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

  12. Planar elliptic growth

    Energy Technology Data Exchange (ETDEWEB)

    Mineev, Mark [Los Alamos National Laboratory

    2008-01-01

    The planar elliptic extension of the Laplacian growth is, after a proper parametrization, given in a form of a solution to the equation for areapreserving diffeomorphisms. The infinite set of conservation laws associated with such elliptic growth is interpreted in terms of potential theory, and the relations between two major forms of the elliptic growth are analyzed. The constants of integration for closed form solutions are identified as the singularities of the Schwarz function, which are located both inside and outside the moving contour. Well-posedness of the recovery of the elliptic operator governing the process from the continuum of interfaces parametrized by time is addressed and two examples of exact solutions of elliptic growth are presented.

  13. Arithmetic of Shimura curves

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    This is the note for a series of lectures that the author gave at the Centre de Recerca Matemtica (CRM), Bellaterra, Barcelona, Spain on October 19–24, 2009. The aim is to give a comprehensive description of some recent work of the author and his students on generalisations of the Gross-Zagier formula, Euler systems on Shimura curves, and rational points on elliptic curves.

  14. Quantitative analysis of spirality in elliptical galaxies

    CERN Document Server

    Dojcsak, Levente

    2013-01-01

    We use an automated galaxy morphology analysis method to quantitatively measure the spirality of galaxies classified manually as elliptical. The data set used for the analysis consists of 60,518 galaxy images with redshift obtained by the Sloan Digital Sky Survey (SDSS) and classified manually by Galaxy Zoo, as well as the RC3 and NA10 catalogues. We measure the spirality of the galaxies by using the Ganalyzer method, which transforms the galaxy image to its radial intensity plot to detect galaxy spirality that is in many cases difficult to notice by manual observation of the raw galaxy image. Experimental results using manually classified elliptical and S0 galaxies with redshift <0.3 suggest that galaxies classified manually as elliptical and S0 exhibit a nonzero signal for the spirality. These results suggest that the human eye observing the raw galaxy image might not always be the most effective way of detecting spirality and curves in the arms of galaxies.

  15. Projected Elliptical Distributions

    Institute of Scientific and Technical Information of China (English)

    Winfried Stute; Uwe Werner

    2005-01-01

    We introduce a new parametrization of elliptically contoured densities and study the associated family of projected (circular) distributions. In particular we investigate the trigonometric moments and some convolution properties.

  16. Effects of Surface Emitting and Cumulative Collisions on Elliptic Flow

    Institute of Scientific and Technical Information of China (English)

    LIU Jian-Li; WU Feng-Juan; ZHANG Jing-Bo; TANG Gui-Xin; HUO Lei

    2008-01-01

    @@ The integral and differential elliptic flow of partons is calculated using the multiphase transport model for Au+Au collisions at centre-of-mass energy √SNN=200 GeV.It is shown that elliptic flow of partons freezing out at early time,which is affected mainly by surface emittance,decreases with time and elliptic flow of partons freezing out at late time,which is dominated by cumulative collisions,increases with time.The elliptic flow of partons freezing out early has a large contribution to the flatting of curve of final differential elliptic flow at large transverse momentum.It is argued that the effect of surface emittance is not neglectable.

  17. $\\mathcal{D}$-elliptic sheaves and odd Jacobians

    CERN Document Server

    Papikian, Mihran

    2011-01-01

    We examine the existence of rational divisors on modular curves of $\\mathcal{D}$-elliptic sheaves and on Atkin-Lehner quotients of these curves over local fields. Using a criterion of Poonen and Stoll, we show that in infinitely many cases the Tate-Shafarevich groups of the Jacobians of these Atkin-Lehner quotients have non-square orders.

  18. Solitons on Noncommutative Torus as Elliptic Algebras and Elliptic Models

    CERN Document Server

    Hou, B Y; Shi, K J; Yue, R H; Hou, Bo-Yu; Peng, Dan-tao; Shi, Kang-Jie; Yue, Rui-Hong

    2001-01-01

    For the noncommutative torus ${\\cal T}$, in case of the N.C. parameter $\\theta = \\frac{Z}{n}$ and the area of ${\\cal T}$ is an integer, we construct the basis of Hilbert space ${\\cal H}_n$ in terms of $\\theta$ functions of the positions of $n$ solitons. The Wilson loop wrapping the solitons around the torus generates the algebra ${\\cal A}_n$. We find that ${\\cal A}_n$ is isomorphic to the $Z_n \\times Z_n$ Heisenberg group on $\\theta$ functions. We find the explicit form for the solitons local translation operators, show that it is the generators $g$ of an elliptic $su(n)$, which transform covariantly by the global gauge transformation of the Wilson loop in ${\\cal A}_n$. Then by acting on ${\\cal H}_n$ we establish the isomorphism of ${\\cal A}_n$ and $g$. Then it is easy to give the projection operators corresponding to the solitons and the ABS construction for generating solitons. We embed this $g$ into elliptic Gaudin and C.M. models to give the dynamics. For $\\theta$ generic case, we introduce the crossing p...

  19. Origin of the colour-magnitude relation of elliptical galaxies

    CERN Document Server

    Kodama, T; Kodama, Tadayuki; Arimoto, Nobuo

    1996-01-01

    Evolutionary models of elliptical galaxies are constructed by using a new population synthesis code. Model parameters are calibrated to reproduce the observed colour-magnitude (CM) relation of Coma ellipticals in $V-K$ vs. $M_{V}$ diagram. The SEDs are degenerated in stellar age and metallicity. An attempt is performed to break this degeneracy, by simulating evolution of the CM relation of elliptical galaxies, based on the two alternative interpretations; i.e., the CM relation reflects different mean stellar age or various stellar metallicity. A confrontation with the CM diagrams of E/S0 galaxies in the two distant clusters Abell 2390 ($z=0.228$) and Abell 851 ($z=0.407$) reinsures previous contentions that the CM relation is primarily a metallicity effect. This conclusion does not depend either on the model parameters, or on the cosmological parameters adopted.

  20. Elliptic grid generation based on Laplace equations and algebraic transformations

    Energy Technology Data Exchange (ETDEWEB)

    Spekreuse, S.P. [National Aerospace Lab., Amsterdam (Netherlands)

    1995-04-01

    An elliptic grid generation method is presented to generate boundary conforming grids in domains in 2D and 3D physical space and on minimal surfaces and parametrized surfaces in 3D physical space. The elliptic grid generation method is based on the use of a composite mapping. This composite mapping consists of a nonlinear transfinite algebraic transformation and an elliptic transformation. The elliptic transformation is based on the Laplace equations for domains, or on the Laplace-Beltrami equations for surfaces. The algebraic transformation maps the computational space one to-one onto a parameter space. The elliptic transformation maps the parameter space one-to-one onto the domains or surfaces. The composition of these two mapping is a differentiable one-to-one mapping from computational space onto the domains or surfaces and has a nonvanishing Jacobian. This composite mapping defines the grid point distribution in the interior of the domains or surfaces. For domains and minimal surfaces, the composite mapping obeys a nonlinear elliptic Poisson system with control functions completely defined by the algebraic transformation. The solution of the Poisson systems is obtained by Picard iteration and black-box multigrid solvers. For parametrized curved surfaces, it is not necessary to define and solve a nonlinear elliptic Poisson system. Instead a linear elliptic system and an inversion problem is solved to generate the grid in the interior of the surface.

  1. Elliptic hypergeometric functions

    CERN Document Server

    Spiridonov, V P

    2016-01-01

    This is author's Habilitation Thesis (Dr. Sci. dissertation) submitted at the beginning of September 2004. It is written in Russian and is posted due to the continuing requests for the manuscript. The content: 1. Introduction, 2. Nonlinear chains with the discrete time and their self-similar solutions, 3. General theory of theta hypergeometric series, 4. Theta hypergeometric integrals, 5. Biorthogonal functions, 6. Elliptic hypergeometric functions with |q|=1, 7. Conclusion, 8. References. It contains an outline of a general heuristic scheme for building univariate special functions through self-similar reductions of spectral transformation chains, which allowed construction of the differential-difference q-Painleve equations, as well as of the most general known set of elliptic biorthogonal functions comprising all classical orthogonal polynomials and biorthogonal rational functions. One of the key results of the thesis consists in the discovery of genuinely transcendental elliptic hypergeometric functions d...

  2. Rarefied elliptic hypergeometric functions

    CERN Document Server

    Spiridonov, V P

    2016-01-01

    We prove exact evaluation formulae for two multiple rarefied elliptic beta integrals related to the simplest lens space. These integrals generalize the multiple type I and II van Diejen-Spiridonov integrals attached to the root system $C_n$. Symmetries of the rarefied elliptic analogue of the Euler-Gauss hypergeometric function are described and the corresponding generalization of the hypergeometric equation is constructed. An extension of the latter function to the root system $C_n$ and applications to some eigenvalue problems are briefly discussed.

  3. On the computing of the Artin Root Number of the elliptic curve Ed2:y2 = x3 - d2 x over the Gaussian integers%关于椭圆曲线Ed2:y2=x3-d2x的Artin Root Number的计算

    Institute of Scientific and Technical Information of China (English)

    佘东明

    2013-01-01

    作者给出了一类椭圆曲线 Ed2:y2= x3- d2 x的Artin Root Number的精确表达式,这里d=π1⋯πrω1⋯ωs q1⋯qt是一些互不相同的“标准”的高斯素数的乘积。这是在赵春来的相关结果的推广。%We give an explicit formula of the Artin root number of the class of elliptic curves Ed2 :y2 = x3- d2 x ,w here d = π1 ...πrω1 ...ωsq1 ...qt is a product of distinct ‘canonical’ Gaussian prime numbers .It is a slight generalization of the relative result from Zhao Chunlai .

  4. Introducing elliptic, an R Package for Elliptic and Modular Functions

    Directory of Open Access Journals (Sweden)

    Robin K. S. Hankin

    2006-01-01

    Full Text Available This paper introduces the elliptic package of R routines, for numerical calculation of elliptic and related functions. Elliptic functions furnish interesting and instructive examples of many ideas of complex analysis, and the package illustrates these numerically and visually. A statistical application in fluid mechanics is presented.

  5. Elliptical flexure hinges

    Science.gov (United States)

    Smith, Stuart T.; Badami, Vivek G.; Dale, Jami S.; Xu, Ying

    1997-03-01

    This paper presents closed form equations based on a modification of those originally derived by Paros and Weisbord in 1965, for the mechanical compliance of a simple monolithic flexure hinge of elliptic cross section, the geometry of which is determined by the ratio ɛ of the major and minor axes. It is shown that these equations converge at ɛ=1 to the Paros and Weisbord equations for a hinge of circular section and at ɛ ⇒∞ to the equations predicted from simple beam bending theory for the compliance of a cantilever beam. These equations are then assessed by comparison with results from finite element analysis over a range of geometries typical of many hinge designs. Based on the finite element analysis, stress concentration factors for the elliptical hinge are also presented. As a further verification of these equations, a number of elliptical hinges were manufactured on a CNC milling machine. Experimental data were produced by applying a bending moment using dead weight loading and measuring subsequent angular deflections with a laser interferometer. In general, it was found that predictions for the compliance of elliptical hinges are likely to be within 12% for a range of geometries with the ratio βx(=t/2ax) between 0.06 and 0.2 and for values of ɛ between 1 and 10.

  6. Elliptic Quantum Billiard

    NARCIS (Netherlands)

    Waalkens, Holger; Wiersig, Jan; Dullin, Holger R.

    1997-01-01

    The exact and semiclassical quantum mechanics of the elliptic billiard is investigated. The classical system is integrable and exhibits a separatrix, dividing the phase space into regions of oscillatory and rotational motion. The classical separability carries over to quantum mechanics, and the Schr

  7. AGB Connection and Ultraviolet Luminosity Excess in Elliptical Galaxies

    CERN Document Server

    Buzzoni, Alberto

    2008-01-01

    Relying on infrared surface brightness fluctuactions to trace AGB properties in a sample of elliptical galaxies in the Virgo and Fornax clusters, we assess the puzzling origin of the "UV-upturn" phenomenon, recently traced down to the presence of a hot horizontal branch stellar component. We find that the UV-upturn actually signals a profound change in the c-m diagram of stellar populations in elliptical galaxies, involving both the hot stellar component and red-giant evolution.

  8. Elliptic Schlesinger system and Painleve VI

    Energy Technology Data Exchange (ETDEWEB)

    Chernyakov, Yu [Institute of Theoretical and Experimental Physics, Moscow (Russian Federation); Levin, A M [Institute of Oceanology, Moscow (Russian Federation); Olshanetsky, M [Institute of Theoretical and Experimental Physics, Moscow (Russian Federation); Zotov, A [Institute of Theoretical and Experimental Physics, Moscow (Russian Federation)

    2006-09-29

    We consider an elliptic generalization of the Schlesinger system (ESS) with positions of marked points on an elliptic curve and its modular parameter as independent variables (the parameters in the moduli space of the complex structure). This system was originally discovered by Takasaki (hep-th/9711095) in the quasi-classical limit of the SL(N) vertex model. Our derivation is purely classical. ESS is defined as a symplectic quotient of the space of connections of bundles of degree 1 over the elliptic curves with marked points. The ESS is a non-autonomous Hamiltonian system with pairwise commuting Hamiltonians. The system is bi-Hamiltonian with respect to the linear and introduced here quadratic Poisson brackets. The latter are the multi-colour form of the Sklyanin-Feigin-Odesski classical algebras. The ESS is the monodromy independence condition on the complex structure for the linear systems related to the flat bundle. The case of four points for a special initial data is reduced to the Painleve VI equation in the form of the Zhukovsky-Volterra gyrostat, proposed in our previous paper.

  9. Elliptic Genera and 3d Gravity

    Energy Technology Data Exchange (ETDEWEB)

    Benjamin, Nathan; /Stanford U., ITP /SLAC; Cheng, Miranda C.N.; /Amsterdam U., Inst. Math.; Kachru, Shamit; /Stanford U., ITP /SLAC; Moore, Gregory W.; /Rutgers U., Piscataway; Paquette, Natalie M.; /Stanford U., ITP /SLAC

    2016-03-30

    We describe general constraints on the elliptic genus of a 2d supersymmetric conformal field theory which has a gravity dual with large radius in Planck units. We give examples of theories which do and do not satisfy the bounds we derive, by describing the elliptic genera of symmetric product orbifolds of K3, product manifolds, certain simple families of Calabi–Yau hypersurfaces, and symmetric products of the “Monster CFT”. We discuss the distinction between theories with supergravity duals and those whose duals have strings at the scale set by the AdS curvature. Under natural assumptions, we attempt to quantify the fraction of (2,2) supersymmetric conformal theories which admit a weakly curved gravity description, at large central charge.

  10. 基于有向性椭圆曲线的改进数字签密算法研究%Improved Digital Signcryption Algorithm Based on Cryptographic Elliptic Curve

    Institute of Scientific and Technical Information of China (English)

    陈画

    2013-01-01

    This article expounds basic information related to digital signature and digital signcryption. Based on the integrated analysis on various existing digital signature programs and signcryption programs, and utilizing the difficulty of oval curve discrete logarithmic problem, this paper proposes the improved digital signcryption algorithm on the basis of aeoplotropism ellipitc curve so as to meet the optimized target of reducing seeking inverse operation in the process of signcryption proof procedure. Aeoplotropism means only the specipient can make the signcryption. Experiments show that this improved algorithm has a significant effect of accelerating operation.%论文首先介绍了数字签名及数字签密的相关基础知识,在综合分析现存各类数字签名方案和签密方案的基础上,以减少签名验证过程中的求逆运算为优化目标,利用椭圆曲线离散对数问题的难解性,该文提出了一类基于有向性椭圆曲线的改进数字签密算法,有向性即只有指定的接收者才能解签密,通过实验证明,该改进算法能够加快运算速度,具有显著的优化效果.

  11. Retrieval of Rayleigh Wave Ellipticity from Ambient Vibration Recordings

    Science.gov (United States)

    Maranò, Stefano; Hobiger, Manuel; Fäh, Donat

    2017-01-01

    The analysis of ambient vibrations is a useful tool in microzonation and geotechnical investigations. Ambient vibrations are composed to a large part of surface waves, both Love and Rayleigh waves. One reason to analyse surface waves is that they carry information about the subsurface. The dispersion curve of Rayleigh waves and Love waves can be retrieved using array processing techniques. The Rayleigh wave ellipticity, including the sense of rotation of the particle motion, can also be retrieved using array techniques. These quantities are used in an inversion procedure aimed at obtaining a structural model of the subsurface. The focus of this work is the retrieval of Rayleigh wave ellipticity. We show applications of the (ML) method presented in Maranó et al. (2012) to a number of sites in Switzerland. The sites examined are chosen to reflect a wide range of soil conditions that are of interest in microzonation studies. Using a synthetic wavefield with known structural model, we compare our results with theoretical ellipticity curves and we show the accuracy of the considered algorithm. The sense of rotation of the particle motion (prograde vs. retrograde) is also estimated. In addition, we show that by modelling the presence of both Love and Rayleigh waves it is possible to mitigate the disruptive influence of Love waves on the estimation of Rayleigh wave ellipticity. Using recordings from several real sites, we show that it is possible to retrieve the ellipticity curve over a broad range of frequencies. Fundamental modes and higher modes are retrieved. Singularities of the ellipticity, corresponding to a change of the sense of rotation from prograde to retrograde (or vice versa), are detected with great accuracy. Knowledge of Rayleigh wave ellipticity, including the sense of rotation, is useful in several ways. The ellipticity angle allows us to pinpoint accurately the frequency of singularities (i.e., peaks and zeros of the H/V representation of the

  12. Ellipticity induced in vacuum birefringence

    CERN Document Server

    Torgrimsson, Greger

    2014-01-01

    We consider signals of photon-photon scattering in laser-based, low energy experiments. In particular, we consider the ellipticity induced on a probe beam by a strong background field, and compare it with a recent worldline expression for the photon polarisation flip amplitude. When the probe and the background are plane waves, the ellipticity is equal to the flip amplitude. Here we investigate the ellipticity-amplitude relation for more physical fields.

  13. Nonlinear elliptic systems

    Directory of Open Access Journals (Sweden)

    DJAIRO G. DEFIGUEIREDO

    2000-12-01

    Full Text Available In this paper we treat the question of the existence of solutions of boundary value problems for systems of nonlinear elliptic equations of the form - deltau = f (x, u, v,Ñu,Ñv, - deltav = g(x, u, v, Ñu, Ñv, in omega, We discuss several classes of such systems using both variational and topological methods. The notion of criticality takes into consideration the coupling, which plays important roles in both a priori estimates for the solutions and Palais-Smale conditions for the associated functional in the variational case.

  14. Degenerate elliptic resonances

    CERN Document Server

    Gentile, G

    2004-01-01

    Quasi-periodic motions on invariant tori of an integrable system of dimension smaller than half the phase space dimension may continue to exists after small perturbations. The parametric equations of the invariant tori can often be computed as formal power series in the perturbation parameter and can be given a meaning via resummations. Here we prove that, for a class of elliptic tori, a resummation algorithm can be devised and proved to be convergent, thus extending to such lower-dimensional invariant tori the methods employed to prove convergence of the Lindstedt series either for the maximal (i.e. KAM) tori or for the hyperbolic lower-dimensional invariant tori

  15. Image Ellipticity from Atmospheric Aberrations

    CERN Document Server

    De Vries, W H; Asztalos, S J; Rosenberg, L J; Baker, K L

    2007-01-01

    We investigate the ellipticity of the point-spread function (PSF) produced by imaging an unresolved source with a telescope, subject to the effects of atmospheric turbulence. It is important to quantify these effects in order to understand the errors in shape measurements of astronomical objects, such as those used to study weak gravitational lensing of field galaxies. The PSF modeling involves either a Fourier transform of the phase information in the pupil plane or a ray-tracing approach, which has the advantage of requiring fewer computations than the Fourier transform. Using a standard method, involving the Gaussian weighted second moments of intensity, we then calculate the ellipticity of the PSF patterns. We find significant ellipticity for the instantaneous patterns (up to more than 10%). Longer exposures, which we approximate by combining multiple (N) images from uncorrelated atmospheric realizations, yield progressively lower ellipticity (as 1 / sqrt(N)). We also verify that the measured ellipticity ...

  16. Ubiquitous CM and DM

    Science.gov (United States)

    Crowley, Sandra L.

    2000-01-01

    Ubiquitous is a real word. I thank a former Total Quality Coach for my first exposure some years ago to its existence. My version of Webster's dictionary defines ubiquitous as "present, or seeming to be present, everywhere at the same time; omnipresent." While I believe that God is omnipresent, I have come to discover that CM and DM are present everywhere. Oh, yes; I define CM as Configuration Management and DM as either Data or Document Management. Ten years ago, I had my first introduction to the CM world. I had an opportunity to do CM for the Space Station effort at the NASA Lewis Research Center. I learned that CM was a discipline that had four areas of focus: identification, control, status accounting, and verification. I was certified as a CMIl graduate and was indoctrinated about clear, concise, and valid. Off I went into a world of entirely new experiences. I was exposed to change requests and change boards first hand. I also learned about implementation of changes, and then of technical and CM requirements.

  17. Elliptic flow in small systems due to elliptic gluon distributions?

    Science.gov (United States)

    Hagiwara, Yoshikazu; Hatta, Yoshitaka; Xiao, Bo-Wen; Yuan, Feng

    2017-08-01

    We investigate the contributions from the so-called elliptic gluon Wigner distributions to the rapidity and azimuthal correlations of particles produced in high energy pp and pA collisions by applying the double parton scattering mechanism. We compute the 'elliptic flow' parameter v2 as a function of the transverse momentum and rapidity, and find qualitative agreement with experimental observations. This shall encourage further developments with more rigorous studies of the elliptic gluon distributions and their applications in hard scattering processes in pp and pA collisions.

  18. Perturbation of sectorial projections of elliptic pseudo-differential operators

    DEFF Research Database (Denmark)

    Booss-Bavnbek, Bernhelm; Chen, Guoyuan; Lesch, Matthias;

    2012-01-01

    Over a closed manifold, we consider the sectorial projection of an elliptic pseudo-differential operator A of positive order with two rays of minimal growth. We showthat it depends continuously on A when the space of pseudo-differential operators is equipped with a certain topology whichwe...... explicitly describe. Our main application deals with a continuous curve of arbitrary first order linear elliptic differential operators over a compact manifold with boundary. Under the additional assumption of the weak inner unique continuation property, we derive the continuity of a related curve...... of Calderón projections and hence of the Cauchy data spaces of the original operator curve. In the Appendix, we describe a topological obstruction against a verbatim use of R. Seeley’s original argument for the complex powers, which was seemingly overlooked in previous studies of the sectorial projection....

  19. Some new addition formulae for Weierstrass elliptic functions.

    Science.gov (United States)

    Eilbeck, J Chris; England, Matthew; Onishi, Yoshihiro

    2014-11-08

    We present new addition formulae for the Weierstrass functions associated with a general elliptic curve. We prove the structure of the formulae in n-variables and give the explicit addition formulae for the 2- and 3-variable cases. These new results were inspired by new addition formulae found in the case of an equianharmonic curve, which we can now observe as a specialization of the results here. The new formulae, and the techniques used to find them, also follow the recent work for the generalization of Weierstrass functions to curves of higher genus.

  20. The two-loop sunrise integral and elliptic polylogarithms

    Energy Technology Data Exchange (ETDEWEB)

    Adams, Luise; Weinzierl, Stefan [Institut fuer Physik, Johannes Gutenberg-Universitaet Mainz (Germany); Bogner, Christian [Institut fuer Physik, Humboldt-Universitaet zu Berlin (Germany)

    2016-07-01

    In this talk, we present a solution for the two-loop sunrise integral with arbitrary masses around two and four space-time dimensions in terms of a generalised elliptic version of the multiple polylogarithms. Furthermore we investigate the elliptic polylogarithms appearing in higher orders in the dimensional regularisation ε of the two-dimensional equal mass solution. Around two space-time dimensions the solution consists of a sum of three elliptic dilogarithms where the arguments have a nice geometric interpretation as intersection points of the integration region and an elliptic curve associated to the sunrise integral. Around four space-time dimensions the sunrise integral can be expressed with the ε{sup 0}- and ε{sup 1}-solution around two dimensions, mass derivatives thereof and simpler terms. Considering higher orders of the two-dimensional equal mass solution we find certain generalisations of the elliptic polylogarithms appearing in the ε{sup 0}- and ε{sup 1}-solutions around two and four space-time dimensions. We show that these higher order-solutions can be found by iterative integration within this class of functions.

  1. A Secured Authentication Protocol for SIP Using Elliptic Curves Cryptography

    Science.gov (United States)

    Chen, Tien-Ho; Yeh, Hsiu-Lien; Liu, Pin-Chuan; Hsiang, Han-Chen; Shih, Wei-Kuan

    Session initiation protocol (SIP) is a technology regularly performed in Internet Telephony, and Hyper Text Transport Protocol (HTTP) as digest authentication is one of the major methods for SIP authentication mechanism. In 2005, Yang et al. pointed out that HTTP could not resist server spoofing attack and off-line guessing attack and proposed a secret authentication with Diffie-Hellman concept. In 2009, Tsai proposed a nonce based authentication protocol for SIP. In this paper, we demonstrate that their protocol could not resist the password guessing attack and insider attack. Furthermore, we propose an ECC-based authentication mechanism to solve their issues and present security analysis of our protocol to show that ours is suitable for applications with higher security requirement.

  2. On Primitive Elements in Finite Fields and on Elliptic Curves

    Science.gov (United States)

    Shparlinskiĭ, I. E.

    1992-02-01

    An asymptotic formula for the number of primitive polynomials of the form f (x) + a, a = 1, ..., h, where f (x)inFp[x], is obtained, "on the average" over all polynomials f of fixed degree, and an estimate for the number of "sparse" factorable polynomials is also obtained.

  3. Elliptic Curve Cryptography on Smart Cards Without Coprocessors

    Science.gov (United States)

    2000-09-20

    Lecture Notes in Computer Science , 1998...implementation for arithmetic operations in GF (2n). In Asiacrypt ’96. Springer-Verlag Lecture Notes in Computer Science , 1996. [9] E. De Win, S. Mister, B...pages 252–266, Berlin, 1998. Springer-Verlag Lecture Notes in Computer Science . [10] P. Gaudry, F. Hess, and N. P. Smart. Constructive and

  4. Cryptanalysis of an Elliptic Curve-based Signcryption Scheme

    CERN Document Server

    Toorani, Mohsen

    2010-01-01

    The signcryption is a relatively new cryptographic technique that is supposed to fulfill the functionalities of encryption and digital signature in a single logical step. Although several signcryption schemes are proposed over the years, some of them are proved to have security problems. In this paper, the security of Han et al.'s signcryption scheme is analyzed, and it is proved that it has many security flaws and shortcomings. Several devastating attacks are also introduced to the mentioned scheme whereby it fails all the desired and essential security attributes of a signcryption scheme.

  5. Secure Authentication of WLAN Based on Elliptic Curve Cryptosystem

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The security of wireless local area network (WLAN) becomes a bottleneck for its further applications.At present, many standard organizations and manufacturers of WLAN try to solve this problem. However, owing to the serious secure leak in IEEE802.11 standards, it is impossible to utterly solve the problem by simply adding some remedies. Based on the analysis on the security mechanism of WLAN and the latest techniques of WLAN security, a solution to WLAN security was presented. The solution makes preparation for the further combination of WLAN and Internet.

  6. The Performance Impact of Elliptic Curve Cryptography on DNSSEC Validation

    NARCIS (Netherlands)

    Rijswijk-Deij, van Roland; Hageman, Kasper; Sperotto, Anna; Pras, Aiko

    2017-01-01

    The Domain Name System is a core Internet infrastructure that translates names to machine-readable information, such as IP addresses. Security flaws in DNS led to a major overhaul, with the introduction of the DNS Security Extensions. DNSSEC adds integrity and authenticity to the DNS using digital s

  7. Making the case for elliptic curves in DNSSEC

    NARCIS (Netherlands)

    Rijswijk-Deij, van Roland; Sperotto, Anna; Pras, Aiko

    2015-01-01

    The Domain Name System Security Extensions (DNSSEC) add authenticity and integrity to the DNS, improving its security. Unfortunately, DNSSEC is not without problems. DNSSEC adds digital signatures to the DNS, significantly increasing the size of DNS responses. This means DNSSEC is more susceptible t

  8. Cubic Curves, Finite Geometry and Cryptography

    CERN Document Server

    Bruen, A A; Wehlau, D L

    2011-01-01

    Some geometry on non-singular cubic curves, mainly over finite fields, is surveyed. Such a curve has 9,3,1 or 0 points of inflexion, and cubic curves are classified accordingly. The group structure and the possible numbers of rational points are also surveyed. A possible strengthening of the security of elliptic curve cryptography is proposed using a `shared secret' related to the group law. Cubic curves are also used in a new way to construct sets of points having various combinatorial and geometric properties that are of particular interest in finite Desarguesian planes.

  9. Elliptical X-Ray Spot Measurement

    CERN Document Server

    Richardson, R A; Weir, J T; Richardson, Roger A.; Sampayan, Stephen; Weir, John T.

    2000-01-01

    The so-called roll bar measurement uses a heavy metal material, optically thick to x-rays, to form a shadow of the x-ray origination spot. This spot is where an energetic electron beam interacts with a high Z target. The material (the "roll bar") is slightly curved to avoid alignment problems. The roll bar is constructed and positioned so that the x-rays are shadowed in the horizontal and vertical directions, so information is obtained in two dimensions. If a beam profile is assumed (or measured by other means), the equivalent x-ray spot size can be calculated from the x-ray shadow cast by the roll bar. Thus the ellipticity of the beam can be calculated, assuming the ellipse of the x-ray spot is aligned with the roll bar. The data is recorded using a scintillator and gated camera. Data will be presented from measurements using the ETA II induction LINAC. The accuracy of the measurement is checked using small elliptical targets.

  10. 关于椭圆曲线y2=x(x+σp)(x+σq)在类数为1虚二次域上的Selmer群及Mordell-Weil群结构%On the Selmer Groups and Mordell-Weil Groups of Elliptic Curves y2 =x(x ± p)(x ± q) Over Imaginary Quadratic Number Fields of Class Number One

    Institute of Scientific and Technical Information of China (English)

    李修美

    2013-01-01

    设p,q为奇素数且q-p=2.本文将在类数为1的虚二次域上考虑椭圆曲线y2=x(x±p)(x±q)及其对偶曲线,并在某些具体条件下给出它们的赛莫群和沙法列维奇-泰特群的(ψ)-(2-)部分的信息.%Let p and q be odd prime numbers with q-p =2.The (ψ)-Selmer groups,Shafarevich-Tate groups((ψ)-and 2-paxt) and their dual ones as well the Mordell-Weil groups of elliptic curves y2 =x(x ± p)(x ± q) over imaginary quadratic number fields of class number one are determined explicitly in many cases.

  11. A Lower Bound for Chaos on the Elliptical Stadium

    CERN Document Server

    Canale, E; Oliffson-Kamphorst, S; De Pinto-Carvalho, S; Canale, Eduardo; Markarian, Roberto; Kamphorst, Sylvie Oliffson; Carvalho, Sonia Pinto de

    1997-01-01

    The elliptical stadium is a plane region bounded by a curve constructed by joining two half-ellipses by two parallel segments of equal length. The billiard inside it, as a map, generates a two parameters family of dynamical systems. It is known that the system is ergodic for a certain region of the parameter space. In this work we study the stability of a particular family of periodic orbits obtaining good bounds for the chaotic zone.

  12. 21 cm Intensity Mapping

    CERN Document Server

    Peterson, Jeffrey B; Ansari, Reza; Bandura, Kevin; Bond, Dick; Bunton, John; Carlson, Kermit; Chang, Tzu-Ching; DeJongh, Fritz; Dobbs, Matt; Dodelson, Scott; Darhmaoui, Hassane; Gnedin, Nick; Halpern, Mark; Hogan, Craig; Goff, Jean-Marc Le; Liu, Tiehui Ted; Legrouri, Ahmed; Loeb, Avi; Loudiyi, Khalid; Magneville, Christophe; Marriner, John; McGinnis, David P; McWilliams, Bruce; Moniez, Marc; Palanque-Delabruille, Nathalie; Pasquinelli, Ralph J; Pen, Ue-Li; Rich, Jim; Scarpine, Vic; Seo, Hee-Jong; Sigurdson, Kris; Seljak, Uros; Stebbins, Albert; Steffen, Jason H; Stoughton, Chris; Timbie, Peter T; Vallinotto, Alberto; Wyithe, Stuart; Yeche, Christophe

    2009-01-01

    Using the 21 cm line, observed all-sky and across the redshift range from 0 to 5, the large scale structure of the Universe can be mapped in three dimensions. This can be accomplished by studying specific intensity with resolution ~ 10 Mpc, rather than via the usual galaxy redshift survey. The data set can be analyzed to determine Baryon Acoustic Oscillation wavelengths, in order to address the question: 'What is the nature of Dark Energy?' In addition, the study of Large Scale Structure across this range addresses the questions: 'How does Gravity effect very large objects?' and 'What is the composition our Universe?' The same data set can be used to search for and catalog time variable and transient radio sources.

  13. Energy and the Elliptical Orbit

    Science.gov (United States)

    Nettles, Bill

    2009-03-01

    In the January 2007 issue of The Physics Teacher, Prentis, Fulton, Hesse, and Mazzino describe a laboratory exercise in which students use a geometrical analysis inspired by Newton to show that an elliptical orbit and an inverse-square law force go hand in hand. The historical, geometrical, and teamwork aspects of the exercise are useful and important. This paper presents an exercise which uses an energy/angular momentum conservation model for elliptical orbits. This exercise can be done easily by an individual student and on regular notebook-sized paper.

  14. Analysis and prediction of area- and energy-consumption of optimized polynomial multipliers in hardware for arbitrary GF(2{sup n}) for elliptic curve cryptography; Analyse und Vorhersage des Flaechen- und Energieverbrauches-optimaler Hardware Polynom-Multiplizierer fuer GF(2{sup n}) fuer elliptische Kurven Kryptographie

    Energy Technology Data Exchange (ETDEWEB)

    Dyka, Zoya

    2012-04-13

    During recent years elliptic curve cryptography (ECC) has gained significant attention especially for devices with scarce resources such as wireless sensor nodes. Hardware implementations are considered to be the key enabler for using ECC on this class of devices. Out of the operations needed to execute ECC the polynomial multiplication is the one which is investigated most since it is one of the most complex field operations and executed very often. The majority of research papers focuses on reducing the number of partial- multiplications while neglecting the increased effort for additions of the partial products. This thesis investigates how the latter can be optimized. A reduction of additions can be achieved by using pre-defined processing sequences for summing up partial products. In this work a method to find the optimized processing sequence is presented. It is applied to 10 multiplication methods of polynomials over GF(2{sup n}). For example when applied to the generalized Karatsuba multiplication [18] the optimized processing sequence saves up to 39 per cent of XOR-gates in average for polynomials with a length up to 600 bits. In addition it is known that combining different multiplication methods reduced the total complexity of the multiplier. For example using the classical MM for calculation of small partial products in combination with other MMs can improve chip-parameters of the resulting multipliers. An optimal combination of several multiplication approaches for which the optimized processing sequence of XOR-operations is used reduces the area and energy consumption of the resulting multiplier significantly. This work presents an algorithm to determine the optimal combination of multiplication methods with pre-defined processing sequences for hardware implementation of an highly efficient polynomial multiplier in GF(2{sup n}). The combinations determined by this algorithm save in average 12 % of the chip-area for polynomials with a length up to 600

  15. Anomalous RR Lyrae stars(?). III. CM Leonis

    CERN Document Server

    Fabrizio, L D; Marconi, M; Carretta, E; Ivans, I I; Bragaglia, A; Tomaso, S D; Merighi, R; Smith, H A; Sneden, C; Tosi, M P

    2002-01-01

    Time series of B,V,I CCD photometry and radial velocity measurements from high resolution spectroscopy (R=30,000) covering the full pulsation cycle are presented for the field RR Lyrae star CM Leonis. The photometric data span a 6 year interval from 1994 to 1999, and allow us to firmly establish the pulsation mode and periodicity of the variable. The derived period P=0.361699 days (+/- 0.000001) is very close to the value published in the Fourth Edition of the General Catalogue of Variable Stars (P=0.361732 days). However, contrary to what was previously found, the amplitude and shape of the light curve qualify CM Leo as a very regular first overtone pulsator with a prominent hump on the rising branch of its multicolour light curves. According to an abundace analysis performed on three spectra taken near minimum light (0.42 < phase < 0.61), CM Leo is a metal-poor star with metal abundance [Fe/H]=-1.93 +/- 0.20. The photometric and radial velocity curves of CM Leo have been compared with the predictions ...

  16. Elliptic Flow Measurement at ALICE

    NARCIS (Netherlands)

    Simili, E.L.

    2008-01-01

    In view of the upcoming ALICE experiment, a dedicated detector to study ultra-relativistic heavy ion collisions at the Large Hadron Collider (LHC) at CERN, the present thesis has been devoted to the study of Elliptic Flow, i.e. the azimuthal anisotropy in the momenta distribution of the final state

  17. Energy and the Elliptical Orbit

    Science.gov (United States)

    Nettles, Bill

    2009-01-01

    In the January 2007 issue of "The Physics Teacher," Prentis, Fulton, Hesse, and Mazzino describe a laboratory exercise in which students use a geometrical analysis inspired by Newton to show that an elliptical orbit and an inverse-square law force go hand in hand. The historical, geometrical, and teamwork aspects of the exercise are useful and…

  18. Fourier Series and Elliptic Functions

    Science.gov (United States)

    Fay, Temple H.

    2003-01-01

    Non-linear second-order differential equations whose solutions are the elliptic functions "sn"("t, k"), "cn"("t, k") and "dn"("t, k") are investigated. Using "Mathematica", high precision numerical solutions are generated. From these data, Fourier coefficients are determined yielding approximate formulas for these non-elementary functions that are…

  19. The ESS elliptical cavity cryomodules

    Science.gov (United States)

    Darve, Christine; Bosland, Pierre; Devanz, Guillaume; Olivier, Gilles; Renard, Bertrand; Thermeau, Jean-Pierre

    2014-01-01

    The European Spallation Source (ESS) is a multi-disciplinary research centre under design and construction in Lund, Sweden. This new facility is funded by a collaboration of 17 European countries and is expected to be up to 30 times brighter than today's leading facilities and neutron sources. The ESS will enable new opportunities for researchers in the fields of life sciences, energy, environmental technology, cultural heritage and fundamental physics. A 5 MW long pulse proton accelerator is used to reach this goal. The pulsed length is 2.86 ms, the repetition frequency is 14 Hz (4 % duty cycle), and the beam current is 62.5 mA. The superconducting section of the Linac accelerates the beam from 80 MeV to 2.0 GeV. It is composed of one string of spoke cavity cryomodule and two strings of elliptical cavity cryomodules. These cryomodules contain four elliptical Niobium cavities operating at 2 K and at a frequency of 704.42 MHz. This paper introduces the thermo-mechanical design, the prototyping and the expected operation of the ESS elliptical cavity cryomodules. An Elliptical Cavity Cryomodule Technology Demonstrator (ECCTD) will be built and tested in order to validate the ESS series production.

  20. TWO PROBLEMS OF HERMITE ELLIPTIC EQUATIONS

    Institute of Scientific and Technical Information of China (English)

    Huaug Feirain

    2009-01-01

    In this article, the author investigates some Hermite elliptic equations in a modified Sobolev space introduced by X. Ding [2]. First, the author shows the existence of a ground state solution of semilinear Hermite elliptic equation. Second, the author studies the eigenvalue problem of linear Hermite elliptic equation in a bounded or unbounded domain.

  1. The Satake sextic in elliptic fibrations on K3

    CERN Document Server

    Malmendier, Andreas

    2016-01-01

    We describe explicit formulas relevant to the F-theory/heterotic string duality that reconstruct from a specific Jacobian elliptic fibration on the Shioda-Inose surface covering a generic Kummer surface the corresponding genus-two curve using the level-two Satake coordinate functions. We derive explicitly the rational map on the moduli space of genus-two curves realizing the algebraic correspondence between a sextic curve and its Satake sextic. We will prove that it is not the original sextic defining the genus-two curve, but its corresponding Satake sextic which is manifest in the F-theory model, dual to the $\\mathfrak{so}(32)$ heterotic string with an unbroken $\\mathfrak{so}(28)\\oplus \\mathfrak{su}(2)$ gauge algebra.

  2. Elliptic Diophantine equations a concrete approach via the elliptic logarithm

    CERN Document Server

    Tzanakis, Nikos

    2013-01-01

    This book presents in a unified way the beautiful and deep mathematics, both theoretical and computational, on which the explicit solution of an elliptic Diophantine equation is based. It collects numerous results and methods that are scattered in literature. Some results are even hidden behind a number of routines in software packages, like Magma. This book is suitable for students in mathematics, as well as professional mathematicians.

  3. Highly curved microchannel plates

    Science.gov (United States)

    Siegmund, O. H. W.; Cully, S.; Warren, J.; Gaines, G. A.; Priedhorsky, W.; Bloch, J.

    1990-01-01

    Several spherically curved microchannel plate (MCP) stack configurations were studied as part of an ongoing astrophysical detector development program, and as part of the development of the ALEXIS satellite payload. MCP pairs with surface radii of curvature as small as 7 cm, and diameters up to 46 mm have been evaluated. The experiments show that the gain (greater than 1.5 x 10 exp 7) and background characteristics (about 0.5 events/sq cm per sec) of highly curved MCP stacks are in general equivalent to the performance achieved with flat MCP stacks of similar configuration. However, gain variations across the curved MCP's due to variations in the channel length to diameter ratio are observed. The overall pulse height distribution of a highly curved surface MCP stack (greater than 50 percent FWHM) is thus broader than its flat counterpart (less than 30 percent). Preconditioning of curved MCP stacks gives comparable results to flat MCP stacks, but it also decreases the overall gain variations. Flat fields of curved MCP stacks have the same general characteristics as flat MCP stacks.

  4. An improved elliptic guide concept for a homogeneous neutron beam without direct line of sight

    CERN Document Server

    Zendler, C; Lieutenant, K

    2014-01-01

    Ballistic neutron guides are efficient for neutron transport over long distances, and in particular elliptically shaped guides have received much attention lately. However, elliptic neutron guides generally deliver an inhomogeneous divergence distribution when used with a small source, and do not allow kinks or curvature to avoid a direct view from source to sample. In this article, a kinked double-elliptic solution is found for neutron transport to a small sample from a small (virtual) source, as given e.g. for instruments using a pinhole beam extraction with a focusing feeder. A guide consisting of two elliptical parts connected by a linear kinked section is shown by VITESS simulations to deliver a high brilliance transfer as well as a homogeneous divergence distribution while avoiding direct line of sight to the source. It performs better than a recently proposed ellipse-parabola hybrid when used in a ballistic context with a kinked or curved central part. Another recently proposed solution, an analyticall...

  5. Transmission eigenvalues for elliptic operators

    CERN Document Server

    Hitrik, Michael; Ola, Petri; Päivärinta, Lassi

    2010-01-01

    A reduction of the transmission eigenvalue problem for multiplicative sign-definite perturbations of elliptic operators with constant coefficients to an eigenvalue problem for a non-selfadjoint compact operator is given. Sufficient conditions for the existence of transmission eigenvalues and completeness of generalized eigenstates for the transmission eigenvalue problem are derived. In the trace class case, the generic existence of transmission eigenvalues is established.

  6. Monte Carlo simulations for focusing elliptical guides

    Energy Technology Data Exchange (ETDEWEB)

    Valicu, Roxana [FRM2 Garching, Muenchen (Germany); Boeni, Peter [E20, TU Muenchen (Germany)

    2009-07-01

    The aim of the Monte Carlo simulations using McStas Programme was to improve the focusing of the neutron beam existing at PGAA (FRM II) by prolongation of the existing elliptic guide (coated now with supermirrors with m=3) with a new part. First we have tried with an initial length of the additional guide of 7,5cm and coatings for the neutron guide of supermirrors with m=4,5 and 6. The gain (calculated by dividing the intensity in the focal point after adding the guide by the intensity at the focal point with the initial guide) obtained for this coatings indicated that a coating with m=5 would be appropriate for a first trial. The next step was to vary the length of the additional guide for this m value and therefore choosing the appropriate length for the maximal gain. With the m value and the length of the guide fixed we have introduced an aperture 1 cm before the focal point and we have varied the radius of this aperture in order to obtain a focused beam. We have observed a dramatic decrease in the size of the beam in the focal point after introducing this aperture. The simulation results, the gains obtained and the evolution of the beam size will be presented.

  7. The Closest Point Method and Multigrid Solvers for Elliptic Equations on Surfaces

    KAUST Repository

    Chen, Yujia

    2015-01-01

    © 2015 Society for Industrial and Applied Mathematics. Elliptic partial differential equations are important from both application and analysis points of view. In this paper we apply the closest point method to solve elliptic equations on general curved surfaces. Based on the closest point representation of the underlying surface, we formulate an embedding equation for the surface elliptic problem, then discretize it using standard finite differences and interpolation schemes on banded but uniform Cartesian grids. We prove the convergence of the difference scheme for the Poisson\\'s equation on a smooth closed curve. In order to solve the resulting large sparse linear systems, we propose a specific geometric multigrid method in the setting of the closest point method. Convergence studies in both the accuracy of the difference scheme and the speed of the multigrid algorithm show that our approaches are effective.

  8. Elliptically distributed lozenge tilings of a hexagon

    CERN Document Server

    Betea, Dan

    2011-01-01

    We present a detailed study of a 4 parameter family of elliptic weights on tilings of a hexagon introduced by Borodin, Gorin and Rains, and generalize some of their results. In the process, we connect the combinatorics of the model with the theory of elliptic special functions. We first analyze some properties of the measure and introduce canonical coordinates that are useful for combinatorially interpreting results. We then show how the computed $n$-point function (called the elliptic Selberg density) and transitional probabilities connect to the theory of $BC_n$-symmetric multivariate elliptic special functions and difference operators discovered by Rains. In particular, the difference operators intrinsically capture the combinatorial model under study, while the elliptic Selberg density is a generalization (deformation) of probability distributions pervasive in the theory of random matrices and interacting particle systems. Based on quasi-commutation relations between elliptic difference operators, we cons...

  9. Parameter likelihood of intrinsic ellipticity correlations

    CERN Document Server

    Capranico, Federica; Schaefer, Bjoern Malte

    2012-01-01

    Subject of this paper are the statistical properties of ellipticity alignments between galaxies evoked by their coupled angular momenta. Starting from physical angular momentum models, we bridge the gap towards ellipticity correlations, ellipticity spectra and derived quantities such as aperture moments, comparing the intrinsic signals with those generated by gravitational lensing, with the projected galaxy sample of EUCLID in mind. We investigate the dependence of intrinsic ellipticity correlations on cosmological parameters and show that intrinsic ellipticity correlations give rise to non-Gaussian likelihoods as a result of nonlinear functional dependencies. Comparing intrinsic ellipticity spectra to weak lensing spectra we quantify the magnitude of their contaminating effect on the estimation of cosmological parameters and find that biases on dark energy parameters are very small in an angular-momentum based model in contrast to the linear alignment model commonly used. Finally, we quantify whether intrins...

  10. Non-paraxial Elliptical Gaussian Beam

    Institute of Scientific and Technical Information of China (English)

    WANG Zhaoying; LIN Qiang; NI Jie

    2001-01-01

    By using the methods of Hertz vector and angular spectrum transormation, the exact solution of non-paraxial elliptical Gaussion beam with general astigmatism based on Maxwell′s equations is obtained. We discussed its propagation characteristics. The results show that the orientation of the elliptical beam spot changes continuously as the beam propagates through isotropic media. Splitting or coupling of beam spots may occur for different initial spot size. This is very different from that of paraxial elliptical Gaussian beam.

  11. Multiple elliptic gamma functions associated to cones

    CERN Document Server

    Winding, Jacob

    2016-01-01

    We define generalizations of the multiple elliptic gamma functions and the multiple sine functions, associated to good rational cones. We explain how good cones are related to collections of $SL_r(\\mathbb{Z})$-elements and prove that the generalized multiple sine and multiple elliptic gamma functions enjoy infinite product representations and modular properties determined by the cone. This generalizes the modular properties of the elliptic gamma function studied by Felder and Varchenko, and the results about the usual multiple sine and elliptic gamma functions found by Narukawa.

  12. Nonparaxial Propagation of Vectorial Elliptical Gaussian Beams

    Directory of Open Access Journals (Sweden)

    Wang Xun

    2016-01-01

    Full Text Available Based on the vectorial Rayleigh-Sommerfeld diffraction integral formulae, analytical expressions for a vectorial elliptical Gaussian beam’s nonparaxial propagating in free space are derived and used to investigate target beam’s propagation properties. As a special case of nonparaxial propagation, the target beam’s paraxial propagation has also been examined. The relationship of vectorial elliptical Gaussian beam’s intensity distribution and nonparaxial effect with elliptic coefficient α and waist width related parameter fω has been analyzed. Results show that no matter what value of elliptic coefficient α is, when parameter fω is large, nonparaxial conclusions of elliptical Gaussian beam should be adopted; while parameter fω is small, the paraxial approximation of elliptical Gaussian beam is effective. In addition, the peak intensity value of elliptical Gaussian beam decreases with increasing the propagation distance whether parameter fω is large or small, and the larger the elliptic coefficient α is, the faster the peak intensity value decreases. These characteristics of vectorial elliptical Gaussian beam might find applications in modern optics.

  13. Nonlinear elliptic-parabolic problems

    CERN Document Server

    Kim, Inwon C

    2012-01-01

    We introduce a notion of viscosity solutions for a general class of elliptic-parabolic phase transition problems. These include the Richards equation, which is a classical model in filtration theory. Existence and uniqueness results are proved via the comparison principle. In particular, we show existence and stability properties of maximal and minimal viscosity solutions for a general class of initial data. These results are new even in the linear case, where we also show that viscosity solutions coincide with the regular weak solutions introduced in [Alt&Luckhaus 1983].

  14. Chopper z-scan technique for elliptic Gaussian beams.

    Science.gov (United States)

    Dávila-Pintle, J A; Reynoso-Lara, E; Bravo-García, Y E

    2016-09-05

    This paper reports an improvement to the chopper z-scan technique for elliptic Gaussian beams. This improvement results in a higher sensitivity by measuring the ratio of eclipsing time to rotating period (duty cycle) of a chopper that eclipses the beam along the main axis. It is shown that the z-scan curve of the major axis is compressed along the z-axis. This compression factor is equal to the ratio between the minor and major axes. It was found that the normalized peak-valley difference with respect to the linear value does not depend on the axis along which eclipsing occurs.

  15. Automorphic forms for elliptic function fields

    CERN Document Server

    Lorscheid, Oliver

    2010-01-01

    Let $F$ be the function field of an elliptic curve $X$ over $\\F_q$. In this paper, we calculate explicit formulas for unramified Hecke operators acting on automorphic forms over $F$. We determine these formulas in the language of the graph of an Hecke operator, for which we use its interpretation in terms of $\\P^1$-bundles on $X$. This allows a purely geometric approach, which involves, amongst others, a classification of the $\\P^1$-bundles on $X$. We apply the computed formulas to calculate the dimension of the space of unramified cusp forms and the support of a cusp form. We show that a cuspidal Hecke eigenform does not vanish in the trivial $\\P^1$-bundle. Further, we determine the space of unramified $F'$-toroidal automorphic forms where $F'$ is the quadratic constant field extension of $F$. It does not contain non-trivial cusp forms. An investigation of zeros of certain Hecke $L$-series leads to the conclusion that the space of unramified toroidal automorphic forms is spanned by the Eisenstein series $E(\\...

  16. Felder's elliptic quantum group and elliptic hypergeometric series on the root system A_n

    CERN Document Server

    Rosengren, Hjalmar

    2010-01-01

    We introduce a generalization of elliptic 6j-symbols, which can be interpreted as matrix elements for intertwiners between corepresentations of Felder's elliptic quantum group. For special parameter values, they can be expressed in terms of multivariable elliptic hypergeometric series related to the root system A_n. As a consequence, we obtain new biorthogonality relations for such series.

  17. Elliptical Fourier analysis: fundamentals, applications, and value for forensic anthropology.

    Science.gov (United States)

    Caple, Jodi; Byrd, John; Stephan, Carl N

    2017-02-17

    The numerical description of skeletal morphology enables forensic anthropologists to conduct objective, reproducible, and structured tests, with the added capability of verifying morphoscopic-based analyses. One technique that permits comprehensive quantification of outline shape is elliptical Fourier analysis. This curve fitting technique allows a form's outline to be approximated via the sum of multiple sine and cosine waves, permitting the profile perimeter of an object to be described in a dense (continuous) manner at a user-defined level of precision. A large amount of shape information (the entire perimeter) can thereby be collected in contrast to other methods relying on sparsely located landmarks where information falling in between the landmarks fails to be acquired. First published in 1982, elliptical Fourier analysis employment in forensic anthropology from 2000 onwards reflects a slow uptake despite large computing power that makes its calculations easy to conduct. Without hurdles arising from calculation speed or quantity, the slow uptake may partly reside with the underlying mathematics that on first glance is extensive and potentially intimidating. In this paper, we aim to bridge this gap by pictorially illustrating how elliptical Fourier harmonics work in a simple step-by-step visual fashion to facilitate universal understanding and as geared towards increased use in forensic anthropology. We additionally provide a short review of the method's utility for osteology, a summary of past uses in forensic anthropology, and software options for calculations that largely save the user the trouble of coding customized routines.

  18. Matrix factorizations and elliptic fibrations

    Science.gov (United States)

    Omer, Harun

    2016-09-01

    I use matrix factorizations to describe branes at simple singularities of elliptic fibrations. Each node of the corresponding Dynkin diagrams of the ADE-type singularities is associated with one indecomposable matrix factorization which can be deformed into one or more factorizations of lower rank. Branes with internal fluxes arise naturally as bound states of the indecomposable factorizations. Describing branes in such a way avoids the need to resolve singularities. This paper looks at gauge group breaking from E8 fibers down to SU (5) fibers due to the relevance of such fibrations for local F-theory GUT models. A purpose of this paper is to understand how the deformations of the singularity are understood in terms of its matrix factorizations. By systematically factorizing the elliptic fiber equation, this paper discusses geometries which are relevant for building semi-realistic local models. In the process it becomes evident that breaking patterns which are identical at the level of the Kodaira type of the fibers can be inequivalent at the level of matrix factorizations. Therefore the matrix factorization picture supplements information which the conventional less detailed descriptions lack.

  19. Matrix factorizations and elliptic fibrations

    Directory of Open Access Journals (Sweden)

    Harun Omer

    2016-09-01

    Full Text Available I use matrix factorizations to describe branes at simple singularities of elliptic fibrations. Each node of the corresponding Dynkin diagrams of the ADE-type singularities is associated with one indecomposable matrix factorization which can be deformed into one or more factorizations of lower rank. Branes with internal fluxes arise naturally as bound states of the indecomposable factorizations. Describing branes in such a way avoids the need to resolve singularities. This paper looks at gauge group breaking from E8 fibers down to SU(5 fibers due to the relevance of such fibrations for local F-theory GUT models. A purpose of this paper is to understand how the deformations of the singularity are understood in terms of its matrix factorizations. By systematically factorizing the elliptic fiber equation, this paper discusses geometries which are relevant for building semi-realistic local models. In the process it becomes evident that breaking patterns which are identical at the level of the Kodaira type of the fibers can be inequivalent at the level of matrix factorizations. Therefore the matrix factorization picture supplements information which the conventional less detailed descriptions lack.

  20. Weak homology of elliptical galaxies

    CERN Document Server

    Bertin, G; Principe, M D

    2002-01-01

    We start by studying a small set of objects characterized by photometric profiles that have been pointed out to deviate significantly from the standard R^{1/4} law. For these objects we confirm that a generic R^{1/n} law, with n a free parameter, can provide superior fits (the best-fit value of n can be lower than 2.5 or higher than 10), better than those that can be obtained by a pure R^{1/4} law, by an R^{1/4}+exponential model, and by other dynamically justified self--consistent models. Therefore, strictly speaking, elliptical galaxies should not be considered homologous dynamical systems. Still, a case for "weak homology", useful for the interpretation of the Fundamental Plane of elliptical galaxies, could be made if the best-fit parameter n, as often reported, correlates with galaxy luminosity L, provided the underlying dynamical structure also follows a systematic trend with luminosity. We demonstrate that this statement may be true even in the presence of significant scatter in the correlation n(L). Pr...

  1. Principal Curves on Riemannian Manifolds

    DEFF Research Database (Denmark)

    Hauberg, Søren

    2015-01-01

    Euclidean statistics are often generalized to Riemannian manifolds by replacing straight-line interpolations with geodesic ones. While these Riemannian models are familiar-looking, they are restricted by the inflexibility of geodesics, and they rely on constructions which are optimal only...... in Euclidean domains. We consider extensions of Principal Component Analysis (PCA) to Riemannian manifolds. Classic Riemannian approaches seek a geodesic curve passing through the mean that optimize a criteria of interest. The requirements that the solution both is geodesic and must pass through the mean tend...... from Hastie & Stuetzle to data residing on a complete Riemannian manifold. We show that for elliptical distributions in the tangent of spaces of constant curvature, the standard principal geodesic is a principal curve. The proposed model is simple to compute and avoids many of the pitfalls...

  2. Isolated elliptical galaxies in the local Universe

    CERN Document Server

    Lacerna, I; Avila-Reese, V; Abonza-Sane, J; del Olmo, A

    2015-01-01

    We have studied a sample of 89 very isolated elliptical galaxies at z < 0.08 and compared their properties with elliptical galaxies located in a high-density environment such as the Coma supercluster. Our aim is to probe the role of environment on the morphological transformation and quenching of elliptical galaxies as a function of mass. In addition, we elucidate about the nature of a particular set of blue and star-forming isolated ellipticals identified here. We study physical properties of ellipticals such as color, specific star formation rate, galaxy size and stellar age as a function of stellar mass and environment based on SDSS data. We analyze in more detail the blue star-forming isolated ellipticals through photometric characterization using GALFIT and infer their star formation history using STARLIGHT. Among the isolated ellipticals ~ 20% are blue, 8% are star-forming and ~ 10% are recently quenched, while among the Coma ellipticals ~ 8% are blue and just <= 1% are star-forming or recently qu...

  3. Spatial scan statistics using elliptic windows

    DEFF Research Database (Denmark)

    Christiansen, Lasse Engbo; Andersen, Jens Strodl; Wegener, Henrik Caspar

    of confocal elliptic windows and propose a new way to present the information when a spatial point process is considered. This method gives smooth changes for smooth expansions of the set of clusters. A simulation study is used to show how the elliptic windows outperforms the usual circular windows...

  4. Elliptic annular Josephson tunnel junctions in an external magnetic field: the statics

    DEFF Research Database (Denmark)

    Monaco, Roberto; Granata, Carmine; Vettoliere, Antonio

    2015-01-01

    symmetric electrodes a transverse magnetic field is equivalent to an in-plane field applied in the direction of the current flow. Varying the ellipse eccentricity we reproduce all known results for linear and ring-shaped JTJs. Experimental data on high-quality Nb/Al-AlOx/Nb elliptic annular junctions...... or in the perpendicular direction. We report a detailed study of both short and long elliptic annular junctions having different eccentricities. For junctions having a normalized perimeter less than one the threshold curves are derived and computed even in the case with one trapped Josephson vortex. For longer junctions...

  5. Elliptically fibered Calabi–Yau manifolds and the ring of Jacobi forms

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Min-xin, E-mail: minxin@ustc.edu.cn [Interdisciplinary Center for Theoretical Study, University of Science and Technology of China, Hefei, Anhui 230026 (China); Katz, Sheldon, E-mail: katz@math.uiuc.edu [Department of Mathematics, University of Illinois at Urbana–Champaign, 1409 W. Green St., Urbana, IL 61801 (United States); Klemm, Albrecht, E-mail: aklemm@th.physik.uni-bonn.de [Bethe Center for Theoretical Physics (BCTP), Physikalisches Institut, Universität Bonn, 53115 Bonn (Germany)

    2015-09-15

    We give evidence that the all genus amplitudes of topological string theory on compact elliptically fibered Calabi–Yau manifolds can be written in terms of meromorphic Jacobi forms whose weight grows linearly and whose index grows quadratically with the base degree. The denominators of these forms have a simple universal form with the property that the poles of the meromorphic form lie only at torsion points. The modular parameter corresponds to the fibre class while the role of the string coupling is played by the elliptic parameter. This leads to very strong all genus results on these geometries, which are checked against results from curve counting.

  6. International Workshop on Elliptic and Parabolic Equations

    CERN Document Server

    Schrohe, Elmar; Seiler, Jörg; Walker, Christoph

    2015-01-01

    This volume covers the latest research on elliptic and parabolic equations and originates from the international Workshop on Elliptic and Parabolic Equations, held September 10-12, 2013 at the Leibniz Universität Hannover. It represents a collection of refereed research papers and survey articles written by eminent scientist on advances in different fields of elliptic and parabolic partial differential equations, including singular Riemannian manifolds, spectral analysis on manifolds, nonlinear dispersive equations, Brownian motion and kernel estimates, Euler equations, porous medium type equations, pseudodifferential calculus, free boundary problems, and bifurcation analysis.

  7. PARTITION PROPERTY OF DOMAIN DECOMPOSITION WITHOUT ELLIPTICITY

    Institute of Scientific and Technical Information of China (English)

    Mo Mu; Yun-qing Huang

    2001-01-01

    Partition property plays a central role in domain decomposition methods. Existing theory essentially assumes certain ellipticity. We prove the partition property for problems without ellipticity which are of practical importance. Example applications include implicit schemes applied to degenerate parabolic partial differential equations arising from superconductors, superfluids and liquid crystals. With this partition property, Schwarz algorithms can be applied to general non-elliptic problems with an h-independent optimal convergence rate. Application to the time-dependent Ginzburg-Landau model of superconductivity is illustrated and numerical results are presented.

  8. Microwave gas breakdown in elliptical waveguides

    Energy Technology Data Exchange (ETDEWEB)

    Koufogiannis, I. D.; Sorolla, E., E-mail: eden.sorolla@epfl.ch; Mattes, M. [École Polytechnique Fédérale de Lausanne, Laboratoire d’Électromagnétisme et d' Acoustique (LEMA), Station 11, CH-1015 Lausanne (Switzerland)

    2014-01-15

    This paper analyzes the microwave gas discharge within elliptical waveguides excited by the fundamental mode. The Rayleigh-Ritz method has been applied to solve the continuity equation. The eigenvalue problem defined by the breakdown condition has been solved and the effective diffusion length of the elliptical waveguide has been calculated, what is used to find the corona threshold. This paper extends the microwave breakdown model developed for circular waveguides and shows the better corona withstanding capabilities of elliptical waveguides. The corona breakdown electric field threshold obtained with the variational method has been compared with the one calculated with the Finite Elements Method, showing excellent agreement.

  9. Elliptic Functions with Disconnected Julia Sets

    Science.gov (United States)

    Koss, Lorelei

    2016-06-01

    In this paper, we investigate elliptic functions of the form fΛ = 1/(1 + (℘Λ)2), where ℘Λ is the Weierstrass elliptic function on a real rhombic lattice. We show that a typical function in this family has a superattracting fixed point at the origin and five other equivalence classes of critical points. We investigate conditions on the lattice which guarantee that fΛ has a double toral band, and we show that this family contains the first known examples of elliptic functions for which the Julia set is disconnected but not Cantor.

  10. Principal Curves on Riemannian Manifolds.

    Science.gov (United States)

    Hauberg, Soren

    2016-09-01

    Euclidean statistics are often generalized to Riemannian manifolds by replacing straight-line interpolations with geodesic ones. While these Riemannian models are familiar-looking, they are restricted by the inflexibility of geodesics, and they rely on constructions which are optimal only in Euclidean domains. We consider extensions of Principal Component Analysis (PCA) to Riemannian manifolds. Classic Riemannian approaches seek a geodesic curve passing through the mean that optimizes a criteria of interest. The requirements that the solution both is geodesic and must pass through the mean tend to imply that the methods only work well when the manifold is mostly flat within the support of the generating distribution. We argue that instead of generalizing linear Euclidean models, it is more fruitful to generalize non-linear Euclidean models. Specifically, we extend the classic Principal Curves from Hastie & Stuetzle to data residing on a complete Riemannian manifold. We show that for elliptical distributions in the tangent of spaces of constant curvature, the standard principal geodesic is a principal curve. The proposed model is simple to compute and avoids many of the pitfalls of traditional geodesic approaches. We empirically demonstrate the effectiveness of the Riemannian principal curves on several manifolds and datasets.

  11. Growth curves for Laron syndrome.

    OpenAIRE

    Laron, Z; Lilos, P; Klinger, B.

    1993-01-01

    Growth curves for children with Laron syndrome were constructed on the basis of repeated measurements made throughout infancy, childhood, and puberty in 24 (10 boys, 14 girls) of the 41 patients with this syndrome investigated in our clinic. Growth retardation was already noted at birth, the birth length ranging from 42 to 46 cm in the 12/20 available measurements. The postnatal growth curves deviated sharply from the normal from infancy on. Both sexes showed no clear pubertal spurt. Girls co...

  12. New non-linear equations and modular form expansion for double-elliptic Seiberg-Witten prepotential

    Energy Technology Data Exchange (ETDEWEB)

    Aminov, G. [ITEP, Moscow (Russian Federation); Moscow Institute of Physics and Technology, Dolgoprudny (Russian Federation); Mironov, A. [ITEP, Moscow (Russian Federation); Lebedev Physics Institute, Moscow (Russian Federation); National Research Nuclear University MEPhI, Moscow (Russian Federation); Institute for Information Transmission Problems, Moscow (Russian Federation); Morozov, A. [ITEP, Moscow (Russian Federation); National Research Nuclear University MEPhI, Moscow (Russian Federation); Institute for Information Transmission Problems, Moscow (Russian Federation)

    2016-08-15

    Integrable N-particle systems have an important property that the associated Seiberg-Witten prepotentials satisfy the WDVV equations. However, this does not apply to the most interesting class of elliptic and double-elliptic systems. Studying the commutativity conjecture for theta functions on the families of associated spectral curves, we derive some other non-linear equations for the perturbative Seiberg-Witten prepotential, which turn out to have exactly the double-elliptic system as their generic solution. In contrast with the WDVV equations, the new equations acquire non-perturbative corrections which are straightforwardly deducible from the commutativity conditions. We obtain such corrections in the first non-trivial case of N = 3 and describe the structure of non-perturbative solutions as expansions in powers of the flat moduli with coefficients that are (quasi)modular forms of the elliptic parameter. (orig.)

  13. New non-linear equations and modular form expansion for double-elliptic Seiberg-Witten prepotential

    CERN Document Server

    Aminov, G; Morozov, A

    2016-01-01

    Integrable N-particle systems have an important property that the associated Seiberg-Witten prepotentials satisfy the WDVV equations. However, this does not apply to the most interesting class of elliptic and double-elliptic systems. Studying the commutativity conjecture for theta-functions on the families of associated spectral curves, we derive some other non-linear equations for the perturbative Seiberg-Witten prepotential, which turn out to have exactly the double-elliptic system as their generic solution. In contrast with the WDVV equations, the new equations acquire non-perturbative corrections which are straightforwardly deducible from the commutativity conditions. We obtain such corrections in the first non-trivial case of N=3 and describe the structure of non-perturbative solutions as expansions in powers of the flat moduli with coefficients that are (quasi)modular forms of the elliptic parameter.

  14. Selection effects at 21cm

    NARCIS (Netherlands)

    Briggs, FH; Davies, JI; Impey, C; Phillipps, S

    1999-01-01

    Surveys in the 21cm line of neutral hydrogen are testing the completeness of the catalogs of nearby galaxies. The remarkable observational fact is that the potential wells that confine gas to sufficient density that it can remain neutral in the face of ionizing radiation also provide sites for star

  15. Elliptical instability in terrestrial planets and moons

    CERN Document Server

    Cébron, David; Moutou, Claire; Gal, Patrice Le; 10.1051/0004-6361/201117741

    2012-01-01

    The presence of celestial companions means that any planet may be subject to three kinds of harmonic mechanical forcing: tides, precession/nutation, and libration. These forcings can generate flows in internal fluid layers, such as fluid cores and subsurface oceans, whose dynamics then significantly differ from solid body rotation. In particular, tides in non-synchronized bodies and libration in synchronized ones are known to be capable of exciting the so-called elliptical instability, i.e. a generic instability corresponding to the destabilization of two-dimensional flows with elliptical streamlines, leading to three-dimensional turbulence. We aim here at confirming the relevance of such an elliptical instability in terrestrial bodies by determining its growth rate, as well as its consequences on energy dissipation, on magnetic field induction, and on heat flux fluctuations on planetary scales. Previous studies and theoretical results for the elliptical instability are re-evaluated and extended to cope with ...

  16. Theory of the quadrature elliptic birdcage coil.

    Science.gov (United States)

    Leifer, M C

    1997-11-01

    This paper presents the theory of the quadrature birdcage coil wound on an elliptic cylindrical former. A conformal transformation of the ellipse to a circular geometry is used to derive the optimal sampling of the continuous surface current distribution to produce uniform magnetic fields within an elliptic cylinder. The analysis is rigorous for ellipses of any aspect ratio and shows how to produce quadrature operation of the elliptic birdcage with a conventional hybrid combiner. Insight gained from the transformation is also used to analyze field homogeneity, find the optimal RF shield shape, and specify component values to produce the correct current distribution in practice. Measurements and images from a 16-leg elliptic birdcage coil at both low and high frequencies show good quadrature performance, homogeneity, and sensitivity.

  17. AC Dielectrophoresis Using Elliptic Electrode Geometry

    Directory of Open Access Journals (Sweden)

    S. M. Rezaul Hasan

    2011-01-01

    Full Text Available This paper presents negative AC dielectrophoretic investigations using elliptic electrode geometry. Simulations of the electric field gradient variation using various ratios of the semimajor and the semiminor axis were carried out to determine the optimum elliptic geometry for the dielectrophoretic electrokinetics of specimen in an assay with laminar (low Reynolds number fluid flow. Experimental setup of the elliptic electrode assembly using PCB fabrication and electrokinetic accumulation of specimen in a dielectrophoretic cage is also being reported. Using an actuating signal between 1 kHz and 1 MHz, successful trapping of 45 μm polystyrene beads suspended in distilled water was demonstrated due to negative dielectrophoresis near 100 kHz using the novel elliptic electrode.

  18. Elliptic Polylogarithms and Basic Hypergeometric Functions

    CERN Document Server

    Passarino, Giampiero

    2016-01-01

    Multiple elliptic polylogarithms can be written as (multiple) integrals of products of basic hypergeometric functions. The latter are computable, to arbitrary precision, using a q-difference equation and q-contiguous relations.

  19. The formation history of elliptical galaxies

    CERN Document Server

    De Lucia, G; White, S D M; Croton, D; Kauffmann, G; Lucia, Gabriella De; Springel, Volker; White, Simon D. M.; Croton, Darren; Kauffmann, Guinevere

    2006-01-01

    We take advantage of the largest high-resolution simulation of cosmic structure growth ever carried out -- the Millennium Simulation of the concordance LambdaCDM cosmogony -- to study how the star formation histories, ages and metallicities of elliptical galaxies depend on environment and on stellar mass. We concentrate on a galaxy formation model which is tuned to fit the joint luminosity/colour/morphology/clustering distribution of low redshift galaxies. Massive ellipticals in this model have higher metal abundances, older luminosity-weighted ages, shorter star formation timescales, but lower assembly redshifts than less massive systems. Within clusters the typical masses, ages and metal abundances of ellipticals are predicted to decrease, on average, with increasing distance from the cluster centre. We also quantify the effective number of progenitors of ellipticals as a function of present stellar mass, finding typical numbers below 2 for M* < 10^{11} Msun, rising to about 5 for the most massive system...

  20. Dynamical family properties and dark halo scaling relations of giant elliptical galaxies

    CERN Document Server

    Gerhard, O E; Saglia, R P; Bender, R; Gerhard, Ortwin; Kronawitter, Andi; Bender, Ralf

    2001-01-01

    Based on a uniform dynamical analysis of line-profile shapes for 21 luminous round elliptical galaxies, we have investigated the dynamical family relations of ellipticals: (i) The circular velocity curves (CVCs) of elliptical galaxies are flat to within ~10% for R>~0.2R_e. (ii) Most ellipticals are moderately radially anisotropic; their dynamical structure is surprisingly uniform. (iii) Elliptical galaxies follow a Tully-Fisher (TF) relation, with v_c^max=300 km/s for an L_B^* galaxy. At given v_c^max, they are ~1 mag fainter in B and appear to have slightly lower baryonic mass than spirals even for maximum M/L_B. (iv) The luminosity dependence of M/L_B is confirmed. The tilt of the Fundamental Plane is not caused by dynamical non-homology, nor only by an increasing dark matter fraction with L. It is, however, consistent with stellar population models based on published metallicities and ages. The main driver is therefore probably metallicity, and a secondary population effect is needed to explain the K-band ...

  1. Heavy Flavour Electron Elliptic Flow

    CERN Document Server

    Gutierrez Ortiz, Nicolas Gilberto

    Due to the large mass of the Charm and Beauty quarks, they are c reated in the very first moments of the ultra-high energy nucleus-nucleus collisions taking place at the CERN LHC, therefore, they should be unaware of the geome try of the colli- sion system and carry no azimuthal anisotropies. Similarly , the energy loss via gluon radiation for these massive quarks should be suppressed, th e so-called dead cone ef- fect. Although the observation of elliptic flow in the electro ns produced through the semileptonic decay of these heavy mesons is an indirect meas urement, throughout this thesis it will be shown that a strong correlation exists between the momentum anisotropy of the mother and daughter particles. In the low t ransverse momentum region such measurement would establish whether or not the s ystem reaches local thermal equilibrium. While at large transverse momentum, t he observation of collec- tivity for the heavy flavours can be understood only if the col lisional and radiative in-medium interaction...

  2. Dust processing in elliptical galaxies

    CERN Document Server

    Hirashita, Hiroyuki; Villaume, Alexa; Srinivasan, Sundar

    2015-01-01

    We reconsider the origin and processing of dust in elliptical galaxies. We theoretically formulate the evolution of grain size distribution, taking into account dust supply from asymptotic giant branch (AGB) stars and dust destruction by sputtering in the hot interstellar medium (ISM), whose temperature evolution is treated by including two cooling paths: gas emission and dust emission (i.e. gas cooling and dust cooling). With our new full treatment of grain size distribution, we confirm that dust destruction by sputtering is too efficient to explain the observed dust abundance even if AGB stars continue to supply dust grains, and that, except for the case where the initial dust-to-gas ratio in the hot gas is as high as $\\sim 0.01$, dust cooling is negligible compared with gas cooling. However, we show that, contrary to previous expectations, cooling does not help to protect the dust; rather, the sputtering efficiency is raised by the gas compression as a result of cooling. We additionally consider grain grow...

  3. Integral Models of Extremal Rational Elliptic Surfaces

    CERN Document Server

    Jarvis, Tyler J; Ricks, Jeremy R

    2009-01-01

    Miranda and Persson classified all extremal rational elliptic surfaces in characteristic zero. We show that each surface in Miranda and Persson's classification has an integral model with good reduction everywhere (except for those of type X_{11}(j), which is an exceptional case), and that every extremal rational elliptic surface over an algebraically closed field of characteristic p > 0 can be obtained by reducing one of these integral models mod p.

  4. An elliptic quantum algebra for sl$_{2}$

    CERN Document Server

    Foda, O E; Jimbo, M; Kedem, R; Miwa, T; Yan, H

    1994-01-01

    An elliptic deformation of \\widehat{sl}_2 is proposed. Our presentation of the algebra is based on the relation RLL=LLR^*, where R and R^* are eight-vertex R-matrices with the elliptic moduli chosen differently. In the trigonometric limit, this algebra reduces to a quotient of that proposed by Reshetikhin and Semenov-Tian-Shansky. Conjectures concerning highest weight modules and vertex operators are formulated, and the physical interpretation of R^* is discussed.

  5. Formation, Evolution and Properties of Isolated Field Elliptical Galaxies

    CERN Document Server

    Niemi, Sami-Matias; Nurmi, Pasi; Saar, Enn

    2010-01-01

    [Abridged] We study the properties, evolution and formation mechanisms of isolated field elliptical galaxies. We create a mock catalogue of isolated field elliptical galaxies from the Millennium Simulation Galaxy Catalogue, and trace their merging histories. The formation, identity and assembly redshifts of simulated isolated and non-isolated elliptical galaxies are studied and compared. Observational and numerical data are used to compare age, mass, and the colour-magnitude relation. Our results, based on simulation data, show that almost seven per cent of all elliptical galaxies brighter than -19mag in B-band can be classified as isolated field elliptical galaxies. Isolated field elliptical galaxies show bluer colours than non-isolated elliptical galaxies and they appear younger, in a statistical sense, according to their mass weighted age. Isolated field elliptical galaxies also form and assemble at lower redshifts compared to non-isolated elliptical galaxies. About 46 per cent of isolated field elliptical...

  6. The “loxodromic”curve and the herringbone

    Directory of Open Access Journals (Sweden)

    Roberto Corazzi

    2012-06-01

    Full Text Available In hemisphere domes the development of the spirals of the herringbone creates a “loxodromic” curve. The curve of the herringbone comes closer and closer to the poles of the sphere. A structure with an octagonal base, presents greater difficulties in the application of this technique; its structure does not have the same continuity as the round dome; as observed previously, each "vela" is a portion of an elliptical cylinder, and not a sphere.

  7. Fabrication of elliptical SRF cavities

    Science.gov (United States)

    Singer, W.

    2017-03-01

    The technological and metallurgical requirements of material for high-gradient superconducting cavities are described. High-purity niobium, as the preferred metal for the fabrication of superconducting accelerating cavities, should meet exact specifications. The content of interstitial impurities such as oxygen, nitrogen, and carbon must be below 10 μg g-1. The hydrogen content should be kept below 2 μg g-1 to prevent degradation of the quality factor (Q-value) under certain cool-down conditions. The material should be free of flaws (foreign material inclusions or cracks and laminations) that can initiate a thermal breakdown. Traditional and alternative cavity mechanical fabrication methods are reviewed. Conventionally, niobium cavities are fabricated from sheet niobium by the formation of half-cells by deep drawing, followed by trim machining and electron beam welding. The welding of half-cells is a delicate procedure, requiring intermediate cleaning steps and a careful choice of weld parameters to achieve full penetration of the joints. A challenge for a welded construction is the tight mechanical and electrical tolerances. These can be maintained by a combination of mechanical and radio-frequency measurements on half-cells and by careful tracking of weld shrinkage. The main aspects of quality assurance and quality management are mentioned. The experiences of 800 cavities produced for the European XFEL are presented. Another cavity fabrication approach is slicing discs from the ingot and producing cavities by deep drawing and electron beam welding. Accelerating gradients at the level of 35-45 MV m-1 can be achieved by applying electrochemical polishing treatment. The single-crystal option (grain boundary free) is discussed. It seems that in this case, high performance can be achieved by a simplified treatment procedure. Fabrication of the elliptical resonators from a seamless pipe as an alternative is briefly described. This technology has yielded good

  8. Elliptic solutions of the restricted Toda chain, Lame polynomials and generalization of the elliptic Stieltjes polynomials

    Energy Technology Data Exchange (ETDEWEB)

    Vinet, Luc [Universite de Montreal, PO Box 6128, Station Centre-ville, Montreal QC H3C 3J7 (Canada); Zhedanov, Alexei [Donetsk Institute for Physics and Technology, Donetsk 83114 (Ukraine)

    2009-10-30

    We construct new families of elliptic solutions of the restricted Toda chain. The main tool is a special (so-called Stieltjes) ansatz for the moments of corresponding orthogonal polynomials. We show that the moments thus obtained are related to three types of Lame polynomials. The corresponding orthogonal polynomials can be considered as a generalization of the Stieltjes-Carlitz elliptic polynomials.

  9. Exposition on affine and elliptic root systems and elliptic Lie algebras

    CERN Document Server

    Azam, Saeid; Yousofzadeh, Malihe

    2009-01-01

    This is an exposition in order to give an explicit way to understand (1) a non-topological proof for an existence of a base of an affine root system, (2) a Serre-type definition of an elliptic Lie algebra with rank =>2, and (3) the isotropic root multiplicities of those elliptic Lie algebras.

  10. Adaptive Finite Element Methods for Elliptic Problems with Discontinuous Coefficients

    KAUST Repository

    Bonito, Andrea

    2013-01-01

    Elliptic PDEs with discontinuous diffusion coefficients occur in application domains such as diffusions through porous media, electromagnetic field propagation on heterogeneous media, and diffusion processes on rough surfaces. The standard approach to numerically treating such problems using finite element methods is to assume that the discontinuities lie on the boundaries of the cells in the initial triangulation. However, this does not match applications where discontinuities occur on curves, surfaces, or manifolds, and could even be unknown beforehand. One of the obstacles to treating such discontinuity problems is that the usual perturbation theory for elliptic PDEs assumes bounds for the distortion of the coefficients in the L∞ norm and this in turn requires that the discontinuities are matched exactly when the coefficients are approximated. We present a new approach based on distortion of the coefficients in an Lq norm with q < ∞ which therefore does not require the exact matching of the discontinuities. We then use this new distortion theory to formulate new adaptive finite element methods (AFEMs) for such discontinuity problems. We show that such AFEMs are optimal in the sense of distortion versus number of computations, and report insightful numerical results supporting our analysis. © 2013 Societ y for Industrial and Applied Mathematics.

  11. The Structure of Galaxies: III. Two Structural Families of Ellipticals

    CERN Document Server

    Schombert, James M

    2015-01-01

    Using isophotal radius correlations for a sample of 2MASS ellipticals, we have constructed a series of template surface brightness profiles to describe the profile shapes of ellipticals as a function of luminosity. The templates are a smooth function of luminosity, yet are not adequately matched to any fitting function supporting the view that ellipticals are weakly non-homologous with respect to structure. Through comparison to the templates, it is discovered that ellipticals are divided into two families; those well matched to the templates and a second class of ellipticals with distinctly shallower profile slopes. We refer to these second type of ellipticals as D class, an old morphological designation acknowledging diffuse appearance on photographic material. D ellipticals cover the same range of luminosity, size and kinematics as normal ellipticals, but maintain a signature of recent equal mass dry mergers. We propose that normal ellipticals grow after an initial dissipation formation era by accretion of...

  12. Effects of electron irradiation and temperature on 1 ohm-cm and 10 ohm-cm silicon solar cells

    Science.gov (United States)

    Nicoletta, C. A.

    1973-01-01

    One OHM-cm and 10 OHM-cm silicon solar cells were exposed to 1.0 MeV electrons at a fixed flux of 10 to the 11th power e/sq cm/sec and fluences of 10 to the 13th power, 10 to the 14th power and 10 to the 15th power e/sq.cm. 1-V curves of the cells were made at room temperature, - 63 C and + or - 143 C after each irradiation. A value of 139.5 mw/sq cm was used as AMO incident energy rate per unit area. The 10 OHM-cm cells appear more efficient than 1 OHM-cm cells after exposure to a fluence greater than 10 to the 14th power e/sq cm. The 1.0 MeV electron damage coefficients for both 1 OHM-cm and 10 OHM-cm cells are somewhat less than those for previously irradiated cells at room temperature. The values of the damage coefficients increase as the cell temperatures decrease. Efficiencies pertaining to maximum power output are about the same as those of n on p silicon cells evaluated previously.

  13. Fast Bilinear Maps from the Tate-Lichtenbaum Pairing on Hyperelliptic Curves

    DEFF Research Database (Denmark)

    Frey, Gerhard; Lange, Tanja

    2006-01-01

    Pairings on elliptic curves recently obtained a lot of attention not only as a means to attack curve based cryptography but also as a building block for cryptosystems with special properties like short signatures or identity based encryption. In this paper we consider the Tate pairing on hyperell...

  14. AGN feedback in elliptical galaxies: numerical simulations

    CERN Document Server

    Ciotti, L

    2011-01-01

    The importance of feedback (radiative and mechanical) from massive black holes at the centers of elliptical galaxies is not in doubt, given the well established relation among black hole mass and galaxy optical luminosity. Here, with the aid of high-resolution hydrodynamical simulations, we discuss how this feedback affects the hot ISM of isolated elliptical galaxies of different mass. The cooling and heating functions include photoionization plus Compton heating, the radiative transport equations are solved, and the mechanical feedback due to the nuclear wind is also described on a physical basis; star formation is considered. In the medium-high mass galaxies the resulting evolution is highly unsteady. At early times major accretion episodes caused by cooling flows in the recycled gas produced by stellar evolution trigger AGN flaring: relaxation instabilities occur so that duty cycles are small enough to account for the very small fraction of massive ellipticals observed to be in the QSO-phase, when the accr...

  15. Local identities involving Jacobi elliptic functions

    Indian Academy of Sciences (India)

    Avinash Khare; Arul Lakshminarayan; Uday Sukhatme

    2004-06-01

    We derive a number of local identities involving Jacobi elliptic functions and use them to obtain several new results. First, we present an alternative, simpler derivation of the cyclic identities discovered by us recently, along with an extension to several new cyclic identities. Second, we obtain a generalization to cyclic identities in which successive terms have a multiplicative phase factor exp$(2i=s)$, where $s$ is any integer. Third, we systematize the local identities by deriving four local `master identities' analogous to the master identities for the cyclic sums discussed by us previously. Fourth, we point out that many of the local identities can be thought of as exact discretizations of standard non-linear differential equations satisfied by the Jacobi elliptic functions. Finally, we obtain explicit answers for a number of definite integrals and simpler forms for several indefinite integrals involving Jacobi elliptic functions.

  16. Nonlinear elliptic equations of the second order

    CERN Document Server

    Han, Qing

    2016-01-01

    Nonlinear elliptic differential equations are a diverse subject with important applications to the physical and social sciences and engineering. They also arise naturally in geometry. In particular, much of the progress in the area in the twentieth century was driven by geometric applications, from the Bernstein problem to the existence of Kähler-Einstein metrics. This book, designed as a textbook, provides a detailed discussion of the Dirichlet problems for quasilinear and fully nonlinear elliptic differential equations of the second order with an emphasis on mean curvature equations and on Monge-Ampère equations. It gives a user-friendly introduction to the theory of nonlinear elliptic equations with special attention given to basic results and the most important techniques. Rather than presenting the topics in their full generality, the book aims at providing self-contained, clear, and "elementary" proofs for results in important special cases. This book will serve as a valuable resource for graduate stu...

  17. The elliptic model for social fluxes

    CERN Document Server

    Herrera-Yagüe, C; Smoreda, Z; Couronné, T; Zufiria, PJ; González, MC

    2013-01-01

    We analyze the anonymous communications patterns of 25 million users from 3 different countries. Grouping costumer by their location (most used phone tower or billing zip code) we build social networks at three levels: tower, city and region for each of the three countries. We propose an elliptic model, which considers the number of relationships between two locations is reversely proportional to the population in the ellipse whose focuses are in such locations. We compare the performance of this model to recent transportation models and find elliptic model overcomes their performance in all scenarios, showing human relationships are at least as influenced by geographical factors as human mobility is.

  18. Electromagnetic Invisibility of Elliptic Cylinder Cloaks

    Institute of Scientific and Technical Information of China (English)

    YAO Kan; LI Chao; LI Fang

    2008-01-01

    Structures with unique electromagnetic properties are designed based on the approach of spatial coordinate transformations of Maxwell's equations.This approach is applied to scheme out invisible elliptic cylinder cloaks,which provide more feasibility for cloaking arbitrarily shaped objects.The transformation expressions for the anisotropic material parameters and the field distribution are derived.The cloaking performances of ideal and lossy elliptic cylinder cloaks are investigated by finite element simulations. It is found that the cloaking performance will degrade in the forward direction with increasing loss.

  19. Effects of proton irradiation and temperature on 1 ohm-cm and 10 ohm-cm silicon solar cells

    Science.gov (United States)

    Nicoletta, C. A.

    1973-01-01

    The 1 ohm-cm and 10 ohm-cm silicon solar cells were exposed to 1.0 MeV protons at a fixed flux of 10 to the 9th power P/sq cm-sec and fluences of 10 to the 10th power, 10 to the 11th power, 10 to the 12th power and 3 X 10 to the 12th power P/sq cm. I-V curves of the cells were made at room temperature, 65 C and 165 C after each irradiation. A value of 139.5 mw/sq cm was taken as AMO incident energy rate per unit area. Degradation occurred for both uncovered 1 ohm-cm and 10 ohm-cm cells. Efficiencies are generally higher than those of comparable U.S. cells tested earlier. Damage (loss in maximum power efficiency) with proton fluence is somewhat higher for 10 ohm-cm cells, measured at the three temperatures, for fluences above 2 X 10 to the 11th power P/sq cm. Cell efficiency, as expected, changes drastically with temperature.

  20. Buckling of elliptical rings under uniform external pressure

    Energy Technology Data Exchange (ETDEWEB)

    Tang, Y.

    1991-04-03

    A thin, elastic elliptical ring is subjected to uniform external pressure. The lowest critical pressure is computed and presented for various ratio of the major axis to the minor axis of the elliptical ring. It is found that the critical pressure for an elliptical ring is higher than that for the circular ring whose diameter is equal to the major axis of the elliptical ring. It can be shown that under the same external pressure, the axial force developed in the elliptical ring is less than that developed in the corresponding circular ring. Thus, a higher pressure is required to buckle the elliptical rings. Therefore, by changing the shape of the ring from circular to elliptical, the capability of the ring to sustain the external pressure can be increased substantially. The results of this study can be useful in the design of elliptical reinforcing rings and thin-walled tubes subjected to external pressure.

  1. Slow Wave Characteristics of Helix Structure with Elliptical Cross Section

    Institute of Scientific and Technical Information of China (English)

    XIE Jian-Xiang; WEI Yan-Yu; GONG Yu-Bin; Fu Cheng-Fang; YUE Ling-Na; WANG Wen-Xiang

    2007-01-01

    We present a novel helix slow wave structure with an elliptical cross section shielded by an elliptical waveguide.The rf characteristics including dispersion properties,interaction impedance of zero mode in this structure have been studied in detail.The theoretical results reveal that weaker dispersion even abnormal dispersion characteristics is obtained with the increasing eccentricity of the elliptical waveguide,while the interaction impedance is enhanced by enlarging the eccentricity of elliptical helix.

  2. The arithmetic of elliptic fibrations in gauge theories on a circle

    Science.gov (United States)

    Grimm, Thomas W.; Kapfer, Andreas; Klevers, Denis

    2016-06-01

    The geometry of elliptic fibrations translates to the physics of gauge theories in F-theory. We systematically develop the dictionary between arithmetic structures on elliptic curves as well as desingularized elliptic fibrations and symmetries of gauge theories on a circle. We show that the Mordell-Weil group law matches integral large gauge transformations around the circle in Abelian gauge theories and explain the significance of Mordell-Weil torsion in this context. We also use Higgs transitions and circle large gauge transformations to introduce a group law for genus-one fibrations with multi-sections. Finally, we introduce a novel arithmetic structure on elliptic fibrations with non-Abelian gauge groups in F-theory. It is defined on the set of exceptional divisors resolving the singularities and divisor classes of sections of the fibration. This group structure can be matched with certain integral non-Abelian large gauge transformations around the circle when studying the theory on the lower-dimensional Coulomb branch. Its existence is required by consistency with Higgs transitions from the non-Abelian theory to its Abelian phases in which it becomes the Mordell-Weil group. This hints towards the existence of a new underlying geometric symmetry.

  3. The arithmetic of elliptic fibrations in gauge theories on a circle

    Energy Technology Data Exchange (ETDEWEB)

    Grimm, Thomas W. [Max-Planck-Institut für Physik,Föhringer Ring 6, 80805 Munich (Germany); Institute for Theoretical Physics,Utrecht University, Leuvenlaan 4, 3584 CE Utrecht (Netherlands); Center for Extreme Matter and Emergent Phenomena,Utrecht University, Leuvenlaan 4, 3584 CE Utrecht (Netherlands); Kapfer, Andreas [Max-Planck-Institut für Physik,Föhringer Ring 6, 80805 Munich (Germany); Klevers, Denis [Theory Group, Physics Department, CERN,CH-1211, Geneva 23 (Switzerland)

    2016-06-20

    The geometry of elliptic fibrations translates to the physics of gauge theories in F-theory. We systematically develop the dictionary between arithmetic structures on elliptic curves as well as desingularized elliptic fibrations and symmetries of gauge theories on a circle. We show that the Mordell-Weil group law matches integral large gauge transformations around the circle in Abelian gauge theories and explain the significance of Mordell-Weil torsion in this context. We also use Higgs transitions and circle large gauge transformations to introduce a group law for genus-one fibrations with multi-sections. Finally, we introduce a novel arithmetic structure on elliptic fibrations with non-Abelian gauge groups in F-theory. It is defined on the set of exceptional divisors resolving the singularities and divisor classes of sections of the fibration. This group structure can be matched with certain integral non-Abelian large gauge transformations around the circle when studying the theory on the lower-dimensional Coulomb branch. Its existence is required by consistency with Higgs transitions from the non-Abelian theory to its Abelian phases in which it becomes the Mordell-Weil group. This hints towards the existence of a new underlying geometric symmetry.

  4. F-Theory Compactifications with Multiple U(1)-Factors: Constructing Elliptic Fibrations with Rational Sections

    CERN Document Server

    Cvetic, Mirjam; Piragua, Hernan

    2013-01-01

    We study F-theory compactifications with U(1)xU(1) gauge symmetry on elliptically fibered Calabi-Yau manifolds with a rank two Mordell-Weil group. We find that the natural presentation of an elliptic curve E with two rational points and a zero point is the generic Calabi-Yau onefold in dP_2. We determine the birational map to its Tate and Weierstrass form and the coordinates of the two rational points in Weierstrass form. We discuss its resolved elliptic fibrations over a general base B and classify them in the case of B=P^2. A thorough analysis of the generic codimension two singularities of these elliptic Calabi-Yau manifolds is presented. This determines the general U(1)xU(1)-charges of matter in corresponding F-theory compactifications. The matter multiplicities for the fibration over P^2 are determined explicitly and shown to be consistent with anomaly cancellation. Explicit toric examples are constructed, both with U(1)xU(1) and SU(5)xU(1)xU(1) gauge symmetry. As a by-product, we prove the birational eq...

  5. The Arithmetic of Elliptic Fibrations in Gauge Theories on a Circle

    CERN Document Server

    Grimm, Thomas W; Klevers, Denis

    2016-01-01

    The geometry of elliptic fibrations translates to the physics of gauge theories in F-theory. We systematically develop the dictionary between arithmetic structures on elliptic curves as well as desingularized elliptic fibrations and symmetries of gauge theories on a circle. We show that the Mordell-Weil group law matches integral large gauge transformations around the circle in Abelian gauge theories and explain the significance of Mordell-Weil torsion in this context. We also use Higgs transitions and circle large gauge transformations to introduce a group law for genus-one fibrations with multi-sections. Finally, we introduce a novel arithmetic structure on elliptic fibrations with non-Abelian gauge groups in F-theory. It is defined on the set of exceptional divisors resolving the singularities and divisor classes of sections of the fibration. This group structure can be matched with certain integral non-Abelian large gauge transformations around the circle when studying the theory on the lower-dimensional ...

  6. Elliptical instability in hot Jupiter systems

    CERN Document Server

    Cébron, David; Gal, Patrice Le; Moutou, Claire; Leconte, J; Sauret, Alban

    2013-01-01

    Several studies have already considered the influence of tides on the evolution of systems composed of a star and a close-in companion to tentatively explain different observations such as the spin-up of some stars with hot Jupiters, the radius anomaly of short orbital period planets and the synchronization or quasi-synchronization of the stellar spin in some extreme cases. However, the nature of the mechanism responsible for the tidal dissipation in such systems remains uncertain. In this paper, we claim that the so-called elliptical instability may play a major role in these systems, explaining some systematic features present in the observations. This hydrodynamic instability, arising in rotating flows with elliptical streamlines, is suspected to be present in both planet and star of such systems, which are elliptically deformed by tides. The presence and the influence of the elliptical instability in gaseous bodies, such as stars or hot Jupiters, are most of the time neglected. In this paper, using numeri...

  7. The sunrise integral and elliptic polylogarithms

    CERN Document Server

    Adams, Luise; Weinzierl, Stefan

    2016-01-01

    We summarize recent computations with a class of elliptic generalizations of polylogarithms, arising from the massive sunrise integral. For the case of arbitrary masses we obtain results in two and four space-time dimensions. The iterated integral structure of our functions allows us to furthermore compute the equal mass case to arbitrary order.

  8. Nonlinear quasimodes near elliptic periodic geodesics

    CERN Document Server

    Albin, Pierre; Marzuola, Jeremy L; Thomann, Laurent

    2011-01-01

    We consider the nonlinear Schr\\"odinger equation on a compact manifold near an elliptic periodic geodesic. Using a geometric optics construction, we construct quasimodes to a nonlinear stationary problem which are highly localized near the periodic geodesic. We show the nonlinear Schr\\"odinger evolution of such a quasimode remains localized near the geodesic, at least for short times.

  9. Nonlinear second order elliptic equations involving measures

    CERN Document Server

    Marcus, Moshe

    2013-01-01

    This book presents a comprehensive study of boundary value problems for linear and semilinear second order elliptic equations with measure data,especially semilinear equations with absorption. The interactions between the diffusion operator and the absorption term give rise to a large class of nonlinear phenomena in the study of which singularities and boundary trace play a central role.

  10. Nomenclature of polarized light - Elliptical polarization

    Science.gov (United States)

    Clarke, D.

    1974-01-01

    Alternative handedness and sign conventions for relating the orientation of elliptical polarization are discussed. The discussion proceeds under two headings: (1) snapshot picture, where the emphasis for the convention is contained in the concept of handedness; and (2) angular momentum consideration, where the emphasis for the convention is strongly associated with mathematical convention and the sign of the fourth Stokes parameter.

  11. Regression Model With Elliptically Contoured Errors

    CERN Document Server

    Arashi, M; Tabatabaey, S M M

    2012-01-01

    For the regression model where the errors follow the elliptically contoured distribution (ECD), we consider the least squares (LS), restricted LS (RLS), preliminary test (PT), Stein-type shrinkage (S) and positive-rule shrinkage (PRS) estimators for the regression parameters. We compare the quadratic risks of the estimators to determine the relative dominance properties of the five estimators.

  12. Circular and Elliptic Submerged Impinging Water Jets

    Science.gov (United States)

    Claudey, Eric; Benedicto, Olivier; Ravier, Emmanuel; Gutmark, Ephraim

    1999-11-01

    Experiments and CFD have been performed to study circular and elliptic jets in a submerged water jet facility. The tests included discharge coefficient measurement to evaluate pressure losses encountered in noncircular nozzles compared to circular ones. Three-dimensional pressure mappings on the impingement surface and PIV measurement of the jet mean and turbulent velocity have been performed at different compound impingement angles relative to the impingement surface and at different stand-off distances. The objective was to investigate the effect of the non-circular geometry on the flow field and on the impact region. The tests were performed in a close loop system in which the water was pumped through the nozzles into a clear Plexiglas tank. The Reynolds numbers were typically in the range of 250000. Discharge coefficients of the elliptic nozzle was somewhat lower than that of the circular jet but spreading rate and turbulence level were higher. Pressure mapping showed that the nozzle exit geometry had an effect on the pressure distribution in the impact region and that high-pressure zones were generated at specific impact points. PIV measurements showed that for a same total exit area, the elliptic jets affected a surface area that is 8the equivalent circular. The turbulence level in the elliptic jet tripled due to the nozzle design. Results of the CFD model were in good agreement with the experimental data.

  13. Spatial scan statistics using elliptic windows

    DEFF Research Database (Denmark)

    Christiansen, Lasse Engbo; Andersen, Jens Strodl; Wegener, Henrik Caspar

    2006-01-01

    The spatial scan statistic is widely used to search for clusters. This article shows that the usually applied elimination of secondary clusters as implemented in SatScan is sensitive to smooth changes in the shape of the clusters. We present an algorithm for generation of a set of confocal elliptic...

  14. Fluxon Dynamics in Elliptic Annular Josephson Junctions

    DEFF Research Database (Denmark)

    Monaco, Roberto; Mygind, Jesper

    2016-01-01

    We analyze the dynamics of a magnetic flux quantum (current vortex) trapped in a current-biased long planar elliptic annular Josephson tunnel junction. The system is modeled by a perturbed sine-Gordon equation that determines the spatial and temporal behavior of the phase difference across the tu...

  15. Solving Nonlinear Wave Equations by Elliptic Equation

    Institute of Scientific and Technical Information of China (English)

    FU Zun-Tao; LIU Shi-Da; LIU Shi-Kuo

    2003-01-01

    The elliptic equation is taken as a transformation and applied to solve nonlinear wave equations. It is shown that this method is more powerful to give more kinds of solutions, such as rational solutions, solitary wave solutions,periodic wave solutions and so on, so it can be taken as a generalized method.

  16. Spatial scan statistics using elliptic windows

    DEFF Research Database (Denmark)

    Christiansen, Lasse Engbo; Andersen, Jens Strodl; Wegener, Henrik Caspar

    2006-01-01

    windows and propose a new way to present the information when a spatial point process is considered. This method gives smooth changes for smooth expansions of the set of clusters. A simulation study is used to show how the elliptic windows outperforms the usual circular windows. The proposed method...

  17. On an asymptotically linear elliptic Dirichlet problem

    Directory of Open Access Journals (Sweden)

    Zhitao Zhang

    2002-01-01

    Full Text Available Under very simple conditions, we prove the existence of one positive and one negative solution of an asymptotically linear elliptic boundary value problem. Even for the resonant case at infinity, we do not need to assume any more conditions to ensure the boundness of the (PS sequence of the corresponding functional. Moreover, the proof is very simple.

  18. Decay of eigenfunctions of elliptic PDE's

    DEFF Research Database (Denmark)

    Herbst, Ira; Skibsted, Erik

    We study exponential decay of eigenfunctions of self-adjoint higher order elliptic operators on Rd. We show that the possible critical decay rates are determined algebraically. In addition we show absence of super-exponentially decaying eigenfunctions and a refined exponential upper bound....

  19. Weight Function Method for Stress Intensity Factor of Internal Surface Semi-elliptical Crack in Elliptical Holes

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The hatches for inspecting are usually designed with elliptical holes in airplane structures, so computation of the stress intensity factor of three dimensional crack at elliptical holes is pivotal for damage tolerance analysis of these structures. In this paper, weight function is derived for a two dimensional through cracks at elliptical holes by applying a compounding method. Stress intensity factor formulas for an internal surface semi-elliptical crack in elliptical holes are obtained using the three dimensional weight function method. Stress intensity factors for an internal surface semi-elliptical crack in elliptical holes under remote tension are computed. At the same time, research on how radius of curvature for elliptical holes affect stress intensity factors was conducted. Stress intensity factors decrease when radius of curvature increases. Some results and conclusions which are of practical value are given.

  20. Performances study of UWB monopole antennas using half-elliptic radiator conformed on elliptical surface

    Science.gov (United States)

    Djidel, S.; Bouamar, M.; Khedrouche, D.

    2016-04-01

    This paper presents a performances study of UWB monopole antenna using half-elliptic radiator conformed on elliptical surface. The proposed antenna, simulated using microwave studio computer CST and High frequency simulator structure HFSS, is designed to operate in frequency interval over 3.1 to 40 GHz. Good return loss and radiation pattern characteristics are obtained in the frequency band of interest. The proposed antenna structure is suitable for ultra-wideband applications, which is, required for many wearable electronics applications.

  1. Jacobi-Bessel Analysis Of Antennas With Elliptical Apertures.

    Science.gov (United States)

    Rahmat-Samii, Y.

    1989-01-01

    Coordinate transformation improves convergence pattern analysis of elliptical-aperture antennas. Modified version of Jacobi-Bessel expansion for vector diffraction analysis of reflector antennas uses coordinate transformation to improve convergence with elliptical apertures. Expansion converges rapidly for antennas with circular apertures, but less rapidly for elliptical apertures. Difference in convergence behavior between circular and elliptical Jacobi-Bessel algorithms indicated by highest values of indices m, n, and p required to achieve same accuracy in computed radiation pattern of offset paraboloidal antenna with elliptical aperture.

  2. Analysis of the Dynamic Characteristics of Elliptical Gears

    Science.gov (United States)

    Liu, Xing; Nagamura, Kazuteru; Ikejo, Kiyotaka

    To date, elliptical gear has been commonly used in automobile, automatic machinery, pumps, flow meters and printing presses for its particular non-uniform rotation. However, the dynamic characteristics of elliptical gears have not been clarified yet. In this study, The calculation as well as the experiment of two elliptical gears, which are a single elliptical gear and a double elliptical gear, is carried out to analyze the dynamic characteristics of elliptical gears. General factors including the torque, the rotation speed and the tooth root stress of the test gears are investigated. According to the analysis conducted in this study, the dynamic input torque variation of elliptical gear becomes larger along with the increase of operating gear rotation speed and the experimental one increases much faster than the calculated one over the Critical Rotation Speed of Tooth Separation (CRSTS) of elliptical gear. The experimental input rotation speed varies according to the variation of input torque, leading to the difference between the experimental output rotation speed and the desired one. The calculation results of the CRSTS of elliptical gears are almost equal to the experimental ones. The dynamic load variation ratios of elliptical gear at different angular position as well as their changing trends with operating gear rotation speed are quite different from each other. And the experimental dynamic load variation ratios of elliptical gear show difference from the calculated ones because of tooth separation and tooth impact. The agreement of the calculation and experimental results proves the validity of this study.

  3. Mining the Suzaku Archive for Elliptical Galaxies

    Science.gov (United States)

    Loewenstein, Michael

    Despite significant progress, our understanding of the formation and evolution of giant elliptical galaxies is incomplete. Many unresolved details about the star formation and assembly history, dissipation and feedback processes, and how these are connected in space and time relate to complex gasdynamical processes that are not directly observable, but that leave clues in the form of the level and pattern of heavy element enrichment in the hot ISM. The low background and relatively sharp spectral resolution of the Suzaku X-ray Observatory XIS CCD detectors enable one to derive a particularly extensive abundance pattern in the hot ISM out to large galactic radii for bright elliptical galaxies. These encode important clues to the chemical and dynamical history of elliptical galaxies. The Suzaku archive now includes data on many of the most suitable galaxies for these purposes. To date, these have been analyzed in a very heterogeneous manner -- some at an early stage in the mission using instrument calibration and analysis tools that have greatly evolved in the interim. Given the level of maturity of the data archive, analysis software, and calibration, the time is right to undertake a uniform analysis of this sample and interpret the results in the context of a coherent theoretical framework for the first time. We propose to (1) carefully and thoroughly analyze the available X-ray luminous elliptical galaxies in the Suzaku database, employing the techniques we have established in our previous work to measure hot ISM abundance patterns. Their interpretation requires careful deconstruction within the context of physical gasdynamical and chemical evolutionary models. Since we have developed models for elliptical galaxy chemical evolution specifically constructed to place constraints on the history and development of these systems based on hot ISM abundances, we are uniquely positioned to interpret -- as well as to analyze -- X-ray spectra of these objects. (2) We will

  4. Mode crosstalk matrix measurement of a 1  km elliptical core few-mode optical fiber.

    Science.gov (United States)

    Milione, Giovanni; Ip, Ezra; Li, Ming-Jun; Stone, Jefferey; Peng, Gaozhu; Wang, Ting

    2016-06-15

    The spatial modes of a 1 km elliptical core few-mode optical fiber (6 spatial modes) are analyzed by using liquid crystal on silicon spatial light modulators to measure the fiber's mode crosstalk matrix in Hermite-Gaussian, Laguerre-Gaussian, and linearly polarized spatial mode bases. It is shown that the fiber's spatial modes can be described by Hermite-Gaussian modes, which can propagate 1 km over the optical fiber with <-20  dB (1%) average mode crosstalk even when the fiber has multiple 1 cm diameter bends. The use of elliptical core few-mode optical fibers for space division multiplexing in data centers is discussed.

  5. A technique for measuring the quality of an elliptically bent pentaerythritol [PET(002)] crystal.

    Science.gov (United States)

    Haugh, M J; Jacoby, K D; Barrios, M A; Thorn, D; Emig, J A; Schneider, M B

    2016-11-01

    We present a technique for determining the X-ray spectral quality from each region of an elliptically curved PET(002) crystal. The investigative technique utilizes the shape of the crystal rocking curve which changes significantly as the radius of curvature changes. This unique quality information enables the spectroscopist to verify where in the spectral range that the spectrometer performance is satisfactory and where there are regions that would show spectral distortion. A collection of rocking curve measurements for elliptically curved PET(002) has been built up in our X-ray laboratory. The multi-lamellar model from the XOP software has been used as a guide and corrections were applied to the model based upon measurements. But, the measurement of RI at small radius of curvature shows an anomalous behavior; the multi-lamellar model fails to show this behavior. The effect of this anomalous RI behavior on an X-ray spectrometer calibration is calculated. It is compared to the multi-lamellar model calculation which is completely inadequate for predicting RI for this range of curvature and spectral energies.

  6. A technique for measuring the quality of an elliptically bent pentaerythritol [PET(002)] crystal

    Science.gov (United States)

    Haugh, M. J.; Jacoby, K. D.; Barrios, M. A.; Thorn, D.; Emig, J. A.; Schneider, M. B.

    2016-11-01

    We present a technique for determining the X-ray spectral quality from each region of an elliptically curved PET(002) crystal. The investigative technique utilizes the shape of the crystal rocking curve which changes significantly as the radius of curvature changes. This unique quality information enables the spectroscopist to verify where in the spectral range that the spectrometer performance is satisfactory and where there are regions that would show spectral distortion. A collection of rocking curve measurements for elliptically curved PET(002) has been built up in our X-ray laboratory. The multi-lamellar model from the XOP software has been used as a guide and corrections were applied to the model based upon measurements. But, the measurement of RI at small radius of curvature shows an anomalous behavior; the multi-lamellar model fails to show this behavior. The effect of this anomalous RI behavior on an X-ray spectrometer calibration is calculated. It is compared to the multi-lamellar model calculation which is completely inadequate for predicting RI for this range of curvature and spectral energies.

  7. The Hodge-elliptic genus, spinning BPS states, and black holes

    CERN Document Server

    Kachru, Shamit

    2016-01-01

    We perform a refined count of BPS states in the compactification of M-theory on $K3 \\times T^2$, keeping track of the information provided by both the $SU(2)_L$ and $SU(2)_R$ angular momenta in the $SO(4)$ little group. Mathematically, this four variable counting function may be expressed via the motivic Donaldson-Thomas counts of $K3 \\times T^2$, simultaneously refining Katz, Klemm, and Pandharipande's motivic Donaldson-Thomas counts on $K3$ and Oberdieck-Pandharipande's Gromov-Witten counts on $K3 \\times T^2$. This provides the first full answer for motivic curve counts of a compact Calabi-Yau threefold. Along the way, we develop a Hodge-elliptic genus for Calabi-Yau manifolds -- a new counting function for BPS states that interpolates between the Hodge polynomial and the elliptic genus of a Calabi-Yau.

  8. The generalized Euler-Poinsot rigid body equations: explicit elliptic solutions

    Science.gov (United States)

    Fedorov, Yuri N.; Maciejewski, Andrzej J.; Przybylska, Maria

    2013-10-01

    The classical Euler-Poinsot case of the rigid body dynamics admits a class of simple but non-trivial integrable generalizations, which modify the Poisson equations describing the motion of the body in space. These generalizations possess first integrals which are polynomial in the angular momenta. We consider the modified Poisson equations as a system of linear equations with elliptic coefficients and show that all the solutions of it are single-valued. By using the vector generalization of the Picard theorem, we derive the solutions explicitly in terms of sigma-functions of the corresponding elliptic curve. The solutions are accompanied by a numerical example. We also compare the generalized Poisson equations with the classical third order Halphen equation.

  9. Collisionless evaporation from cluster elliptical galaxies

    CERN Document Server

    Muccione, V

    2003-01-01

    We describe a particular aspect of the effects of the parent cluster tidal field (CTF) on stellar orbits inside cluster Elliptical galaxies. In particular we discuss, with the aid of a simple numerical model, the possibility that collisionless stellar evaporation from elliptical galaxies is an effective mechanism for the production of the recently discovered intracluster stellar populations. A preliminary investigation, based on very idealized galaxy density profiles (Ferrers density distributions), showed that over an Hubble time, the amount of stars lost by a representative galaxy may sum up to the 10% of the initial galaxy mass, a fraction in interesting agreement with observational data. The effectiveness of this mechanism is due to the fact that the galaxy oscillation periods near equilibrium configurations in the CTF are comparable to stellar orbital times in the external galaxy regions. Here we extend our previous study to more realistic galaxy density profiles, in particular by adopting a triaxial Her...

  10. Elliptic differential equations theory and numerical treatment

    CERN Document Server

    Hackbusch, Wolfgang

    2017-01-01

    This book simultaneously presents the theory and the numerical treatment of elliptic boundary value problems, since an understanding of the theory is necessary for the numerical analysis of the discretisation. It first discusses the Laplace equation and its finite difference discretisation before addressing the general linear differential equation of second order. The variational formulation together with the necessary background from functional analysis provides the basis for the Galerkin and finite-element methods, which are explored in detail. A more advanced chapter leads the reader to the theory of regularity. Individual chapters are devoted to singularly perturbed as well as to elliptic eigenvalue problems. The book also presents the Stokes problem and its discretisation as an example of a saddle-point problem taking into account its relevance to applications in fluid dynamics.

  11. Performance of an elliptically tapered neutron guide

    Science.gov (United States)

    Mühlbauer, Sebastian; Stadlbauer, Martin; Böni, Peter; Schanzer, Christan; Stahn, Jochen; Filges, Uwe

    2006-11-01

    Supermirror coated neutron guides are used at all modern neutron sources for transporting neutrons over large distances. In order to reduce the transmission losses due to multiple internal reflection of neutrons, ballistic neutron guides with linear tapering have been proposed and realized. However, these systems suffer from an inhomogeneous illumination of the sample. Moreover, the flux decreases significantly with increasing distance from the exit of the neutron guide. We propose using elliptically tapered guides that provide a more homogeneous phase space at the sample position as well as a focusing at the sample. Moreover, the design of the guide system is simplified because ellipses are simply defined by their long and short axes. In order to prove the concept we have manufactured a doubly focusing guide and investigated its properties with neutrons. The experiments show that the predicted gains using the program package McStas are realized. We discuss several applications of elliptic guides in various fields of neutron physics.

  12. Performance of an elliptically tapered neutron guide

    Energy Technology Data Exchange (ETDEWEB)

    Muehlbauer, Sebastian [Physik-Department E21, Technische Universitaet Muenchen, D-85747 Garching (Germany)]. E-mail: sebastian.muehlbauer@frm2.tum.de; Stadlbauer, Martin [Physik-Department E21, Technische Universitaet Muenchen, D-85747 Garching (Germany); Boeni, Peter [Physik-Department E21, Technische Universitaet Muenchen, D-85747 Garching (Germany); Schanzer, Christan [Labor fuer Neutronenstreuung, Paul Scherrer Institut, CH-5232 Villingen PSI (Switzerland); Stahn, Jochen [Labor fuer Neutronenstreuung, Paul Scherrer Institut, CH-5232 Villingen PSI (Switzerland); Filges, Uwe [Labor fuer Neutronenstreuung, Paul Scherrer Institut, CH-5232 Villingen PSI (Switzerland)

    2006-11-15

    Supermirror coated neutron guides are used at all modern neutron sources for transporting neutrons over large distances. In order to reduce the transmission losses due to multiple internal reflection of neutrons, ballistic neutron guides with linear tapering have been proposed and realized. However, these systems suffer from an inhomogeneous illumination of the sample. Moreover, the flux decreases significantly with increasing distance from the exit of the neutron guide. We propose using elliptically tapered guides that provide a more homogeneous phase space at the sample position as well as a focusing at the sample. Moreover, the design of the guide system is simplified because ellipses are simply defined by their long and short axes. In order to prove the concept we have manufactured a doubly focusing guide and investigated its properties with neutrons. The experiments show that the predicted gains using the program package McStas are realized. We discuss several applications of elliptic guides in various fields of neutron physics.

  13. Modelling elliptically polarised Free Electron Lasers

    CERN Document Server

    Henderson, J R; Freund, H P; McNeil, B W J

    2016-01-01

    A model of a Free Electron Laser operating with an elliptically polarised undulator is presented. The equations describing the FEL interaction, including resonant harmonic radiation fields, are averaged over an undulator period and generate a generalised Bessel function scaling factor, similar to that of planar undulator FEL theory. Comparison between simulations of the averaged model with those of an unaveraged model show very good agreement in the linear regime. Two unexpected results were found. Firstly, an increased coupling to harmonics for elliptical rather than planar polarisarised undulators. Secondly, and thought to be unrelated to the undulator polarisation, a signficantly different evolution between the averaged and unaveraged simulations of the harmonic radiation evolution approaching FEL saturation.

  14. The invertible double of elliptic operators

    DEFF Research Database (Denmark)

    Booss-Bavnbek, Bernhelm; Lesch, Matthias; Zhu, Chaofeng

    We construct a canonical invertible double for general first order elliptic differential operators over smooth compact manifolds with boundary and derive a natural formula for the Calderon projector which yields a generalization of the famous Cobordism Theorem. Assuming symmetric principal symbol...... of the tangential operator and unique continuation property (UCP) from the boundary, we obtain the continuous dependence of the Calderon projection on the data. The details of our results are available on arxiv arXiv:0803.4160 .......We construct a canonical invertible double for general first order elliptic differential operators over smooth compact manifolds with boundary and derive a natural formula for the Calderon projector which yields a generalization of the famous Cobordism Theorem. Assuming symmetric principal symbol...

  15. Electron capture from coherent elliptic Rydberg states

    Energy Technology Data Exchange (ETDEWEB)

    Day, J.C.; DePaola, B.D.; Ehrenreich, T.; Hansen, S.B.; Horsdal-Pedersen, E.; Leontiev, Y.; Mogensen, K.S. [Institute of Physics and Astronomy, University of Aarhus, DK-8000 Aarhus C (Denmark)

    1997-12-01

    Experimental relative cross sections for electron capture by singly charged ions (Na{sup +}) from coherent elliptic states of principal quantum number n=25 are presented. An interval of reduced impact velocities from about 1{endash}2 is covered. Absolute reaction cross sections could not be determined precisely, but the eccentricity of the coherent elliptic states and their orientation relative to the ion-impact velocity were varied to expose the dependence of the electron-capture process on the initial motion of the electron. The dependencies on eccentricity and orientation are generally strong and they vary sharply with impact velocity. Qualitatively, the observations agree fairly well with classical trajectory Monte Carlo (CTMC) calculations, as expected for the large quantum numbers involved, but significant deviations of a systematic nature do remain, showing that some aspects of the capture reactions studied are described poorly by classical physics as represented by the CTMC model. {copyright} {ital 1997} {ital The American Physical Society}

  16. The Shapes and Ages of Elliptical Galaxies

    CERN Document Server

    De Jong, R S; Jong, Roelof S. de; Davies, Roger L.

    1996-01-01

    In this paper we investigate the relation between the detailed isophotal shape of elliptical galaxies and the strength of the H beta absorption in their spectra. We find that disky galaxies have higher H beta indices. Stellar population synthesis models show that the H beta line is a good age indicator, hence disky galaxies tend to have younger mean ages than boxy galaxies. We show that the observed trend can be brought about by a contaminating young population, which we associate with the disky component. This population need only account for a small fraction of the total mass, for example if a contaminating population of age of 2 Gyrs is superimposed on an old (12 Gyr) elliptical galaxy, then the observed trend can be explained if it contributes only 10% to the total mass. The size of this effect is consistent with the estimates of disk-to-total light ratios from surface photometry.

  17. Fast adaptive elliptical filtering using box splines

    CERN Document Server

    Chaudhury, Kunal Narayan; Unser, Michael

    2009-01-01

    We demonstrate that it is possible to filter an image with an elliptic window of varying size, elongation and orientation with a fixed computational cost per pixel. Our method involves the application of a suitable global pre-integrator followed by a pointwise-adaptive localization mesh. We present the basic theory for the 1D case using a B-spline formalism and then appropriately extend it to 2D using radially-uniform box splines. The size and ellipticity of these radially-uniform box splines is adaptively controlled. Moreover, they converge to Gaussians as the order increases. Finally, we present a fast and practical directional filtering algorithm that has the capability of adapting to the local image features.

  18. MIB Galerkin method for elliptic interface problems

    Science.gov (United States)

    Xia, Kelin; Zhan, Meng; Wei, Guo-Wei

    2014-01-01

    Summary Material interfaces are omnipresent in the real-world structures and devices. Mathematical modeling of material interfaces often leads to elliptic partial differential equations (PDEs) with discontinuous coefficients and singular sources, which are commonly called elliptic interface problems. The development of high-order numerical schemes for elliptic interface problems has become a well defined field in applied and computational mathematics and attracted much attention in the past decades. Despite of significant advances, challenges remain in the construction of high-order schemes for nonsmooth interfaces, i.e., interfaces with geometric singularities, such as tips, cusps and sharp edges. The challenge of geometric singularities is amplified when they are associated with low solution regularities, e.g., tip-geometry effects in many fields. The present work introduces a matched interface and boundary (MIB) Galerkin method for solving two-dimensional (2D) elliptic PDEs with complex interfaces, geometric singularities and low solution regularities. The Cartesian grid based triangular elements are employed to avoid the time consuming mesh generation procedure. Consequently, the interface cuts through elements. To ensure the continuity of classic basis functions across the interface, two sets of overlapping elements, called MIB elements, are defined near the interface. As a result, differentiation can be computed near the interface as if there is no interface. Interpolation functions are constructed on MIB element spaces to smoothly extend function values across the interface. A set of lowest order interface jump conditions is enforced on the interface, which in turn, determines the interpolation functions. The performance of the proposed MIB Galerkin finite element method is validated by numerical experiments with a wide range of interface geometries, geometric singularities, low regularity solutions and grid resolutions. Extensive numerical studies confirm

  19. Elliptic stars in a chaotic night

    CERN Document Server

    Jaeger, T

    2010-01-01

    We study homeomorphisms of the two-torus, homotopic to the identity, whose rotation set has non-empty interior. For such maps, we give a purely topological characterisation of elliptic islands in a chaotic sea in terms of local rotation subsets. We further show that the chaotic regime defined in this way cannot contain any Lyapunov stable points. In order to demonstrate our results, we introduce a parameter family inspired by an example of Misiurewicz and Ziemian.

  20. On a fourth order superlinear elliptic problem

    Directory of Open Access Journals (Sweden)

    M. Ramos

    2001-01-01

    Full Text Available We prove the existence of a nonzero solution for the fourth order elliptic equation $$Delta^2u= mu u +a(xg(u$$ with boundary conditions $u=Delta u=0$. Here, $mu$ is a real parameter, $g$ is superlinear both at zero and infinity and $a(x$ changes sign in $Omega$. The proof uses a variational argument based on the argument by Bahri-Lions cite{BL}.

  1. Photoacoustic cell using elliptical acoustic focusing

    Science.gov (United States)

    Heritier, J.-M.; Fouquet, J. E.; Siegman, A. E.

    1982-01-01

    A photoacoustic cell has been developed in the form of an elliptical cylinder in which essentially all the acoustic energy generated by a laser beam passing down one axis is focused onto a cylindrical acoustic tranducer located along the other axis. Preliminary measurements on a liquid-filled cell of this design show high sensitivity and a notably clean impulse response. A similar design may be useful for photoacoustic measurements in vapors as well.

  2. Evaluation of Fifth Degree Elliptic Singular Moduli

    CERN Document Server

    Bagis, Nikos

    2012-01-01

    Our main result in this article is a formula for the extraction of the solution of the fifth degree modular polynomial equation i.e. the value of $k_{25^nr_0}$, when we know only two consecutive values $k_{r_0}$ and $k_{r_0/25}$. By this way we reduce the problem of solving the depressed equation if we known two consecutive values of the Elliptic singular moduli $k_r$.

  3. Deformed Virasoro Algebras from Elliptic Quantum Algebras

    Science.gov (United States)

    Avan, J.; Frappat, L.; Ragoucy, E.

    2017-09-01

    We revisit the construction of deformed Virasoro algebras from elliptic quantum algebras of vertex type, generalizing the bilinear trace procedure proposed in the 1990s. It allows us to make contact with the vertex operator techniques that were introduced separately at the same period. As a by-product, the method pinpoints two critical values of the central charge for which the center of the algebra is extended, as well as (in the gl(2) case) a Liouville formula.

  4. MIB Galerkin method for elliptic interface problems.

    Science.gov (United States)

    Xia, Kelin; Zhan, Meng; Wei, Guo-Wei

    2014-12-15

    Material interfaces are omnipresent in the real-world structures and devices. Mathematical modeling of material interfaces often leads to elliptic partial differential equations (PDEs) with discontinuous coefficients and singular sources, which are commonly called elliptic interface problems. The development of high-order numerical schemes for elliptic interface problems has become a well defined field in applied and computational mathematics and attracted much attention in the past decades. Despite of significant advances, challenges remain in the construction of high-order schemes for nonsmooth interfaces, i.e., interfaces with geometric singularities, such as tips, cusps and sharp edges. The challenge of geometric singularities is amplified when they are associated with low solution regularities, e.g., tip-geometry effects in many fields. The present work introduces a matched interface and boundary (MIB) Galerkin method for solving two-dimensional (2D) elliptic PDEs with complex interfaces, geometric singularities and low solution regularities. The Cartesian grid based triangular elements are employed to avoid the time consuming mesh generation procedure. Consequently, the interface cuts through elements. To ensure the continuity of classic basis functions across the interface, two sets of overlapping elements, called MIB elements, are defined near the interface. As a result, differentiation can be computed near the interface as if there is no interface. Interpolation functions are constructed on MIB element spaces to smoothly extend function values across the interface. A set of lowest order interface jump conditions is enforced on the interface, which in turn, determines the interpolation functions. The performance of the proposed MIB Galerkin finite element method is validated by numerical experiments with a wide range of interface geometries, geometric singularities, low regularity solutions and grid resolutions. Extensive numerical studies confirm the

  5. A Jacobian elliptic single-field inflation

    Energy Technology Data Exchange (ETDEWEB)

    Villanueva, J.R. [Universidad de Valparaiso, Instituto de Fisica y Astronomia, Valparaiso (Chile); Centro de Astrofisica de Valparaiso, Valparaiso (Chile); Gallo, Emanuel [FaMAF, Universidad Nacional de Cordoba, Cordoba (Argentina); Instituto de Fisica Enrique Gaviola (IFEG), CONICET, Cordoba (Argentina)

    2015-06-15

    In the scenario of single-field inflation, this field is described in terms of Jacobian elliptic functions. This approach provides, when constrained to particular cases, analytic solutions already known in the past, generalizing them to a bigger family of analytical solutions. The emergent cosmology is analyzed using the Hamilton-Jacobi approach and then the main results are contrasted with the recent measurements obtained from the Planck 2015 data. (orig.)

  6. A Jacobian elliptic single-field inflation

    CERN Document Server

    Villanueva, J R

    2015-01-01

    In the scenario of single-field inflation, this field is done in terms of Jacobian elliptic functions. This approach provides, when constrained to particular cases, analytic solutions already known in the past, generalizing them to a bigger family of analytical solutions. The emergent cosmology is analysed using the Hamilton-Jacobi approach and then, the main results are contrasted with the recent measurements obtained from the Planck 2015 data.

  7. Radio Mode Outbursts in Giant Elliptical Galaxies

    CERN Document Server

    Nulsen, Paul; Forman, William; Churazov, Eugene; McNamara, Brian; David, Laurence; Murray, Stephen

    2009-01-01

    Outbursts from active galactic nuclei (AGN) affect the hot atmospheres of isolated giant elliptical galaxies (gE's), as well as those in groups and clusters of galaxies. Chandra observations of a sample of nearby gE's show that the average power of AGN outbursts is sufficient to stop their hot atmospheres from cooling and forming stars, consistent with radio mode feedback models. The outbursts are intermittent, with duty cycles that increases with size.

  8. Limits of Functions and Elliptic Operators

    Indian Academy of Sciences (India)

    Siddhartha Gadgil

    2004-05-01

    We show that a subspace of the space of real analytical functions on a manifold that satisfies certain regularity properties is contained in the set of solutions of a linear elliptic differential equation. The regularity properties are that is closed in $L^2(M)$ and that if a sequence of functions $f_n$ in converges in $L^2(M)$, then so do the partial derivatives of the functions $f_n$.

  9. LAMINAR FLUID FLOW IN HELICAL ELLIPTICAL PIPE

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    In this paper, using an orthogonal curvilinear coordinate system and solving the complete N-S equations, we analyzed the flow in a helical elliptical duct by the perturbation method. The first-order solutions of the stream function Ψ, axial velocity w and the velocity of secondary flow (u, v) were obtained. The effects of torsion, curvature and the axial pressure gradient on the secondary flow were discussed in detail. The study indicates that the torsion has first-order effect on the secondary flow in a helical elliptical pipe, the secondary flow is dominated by torsion when the axial pressure gradient is small and for increasing gradient the secondary flow is eventually dominated by the effect due to curvature. The fact that the torsion has no effect on fluid flow in a helical pipe with a circular cross section was also confirmed. The most important conclusion is that the flow in a helical elliptical pipe to the first-order can be obtained as a combination of the flow in a toroidal pipe and the flow in a twisted pipe.

  10. The Stellar Halos of Massive Elliptical Galaxies

    CERN Document Server

    Greene, Jenny E; Comerford, Julia M; Gebhardt, Karl; Adams, Joshua J

    2012-01-01

    We use the Mitchell Spectrograph (formerly VIRUS-P) on the McDonald Observatory 2.7m Harlan J. Smith Telescope to search for the chemical signatures of massive elliptical galaxy assembly. The Mitchell Spectrograph is an integral-field spectrograph with a uniquely wide field of view (107x107 sq arcsec), allowing us to achieve remarkably high signal-to-noise ratios of ~20-70 per pixel in radial bins of 2-2.5 times the effective radii of the eight galaxies in our sample. Focusing on a sample of massive elliptical galaxies with stellar velocity dispersions sigma* > 150 km/s, we study the radial dependence in the equivalent widths (EWs) of key metal absorption lines. By twice the effective radius, the Mgb EWs have dropped by ~50%, and only a weak correlation between sigma* and Mgb EW remains. The Mgb EWs at large radii are comparable to those seen in the centers of elliptical galaxies that are approximately an order of magnitude less massive. We find that the well-known metallicity gradients often observed within ...

  11. Elliptic Solvers for Adaptive Mesh Refinement Grids

    Energy Technology Data Exchange (ETDEWEB)

    Quinlan, D.J.; Dendy, J.E., Jr.; Shapira, Y.

    1999-06-03

    We are developing multigrid methods that will efficiently solve elliptic problems with anisotropic and discontinuous coefficients on adaptive grids. The final product will be a library that provides for the simplified solution of such problems. This library will directly benefit the efforts of other Laboratory groups. The focus of this work is research on serial and parallel elliptic algorithms and the inclusion of our black-box multigrid techniques into this new setting. The approach applies the Los Alamos object-oriented class libraries that greatly simplify the development of serial and parallel adaptive mesh refinement applications. In the final year of this LDRD, we focused on putting the software together; in particular we completed the final AMR++ library, we wrote tutorials and manuals, and we built example applications. We implemented the Fast Adaptive Composite Grid method as the principal elliptic solver. We presented results at the Overset Grid Conference and other more AMR specific conferences. We worked on optimization of serial and parallel performance and published several papers on the details of this work. Performance remains an important issue and is the subject of continuing research work.

  12. Multiphasic growth curve analysis.

    NARCIS (Netherlands)

    Koops, W.J.

    1986-01-01

    Application of a multiphasic growth curve is demonstrated with 4 data sets, adopted from literature. The growth curve used is a summation of n logistic growth functions. Human height growth curves of this type are known as "double logistic" (n = 2) and "triple logistic" (n = 3) growth curves (Bock

  13. Elliptical Galaxies: Rotationally Distorted, After All

    Directory of Open Access Journals (Sweden)

    Caimmi, R.

    2009-12-01

    Full Text Available On the basis of earlier investigations onhomeoidally striated Mac Laurin spheroids and Jacobi ellipsoids (Caimmi and Marmo2005, Caimmi 2006a, 2007, different sequences of configurations are defined and represented in the ellipticity-rotation plane, $({sf O}hat{e}chi_v^2$. The rotation parameter, $chi_v^2$, is defined as the ratio, $E_mathrm{rot}/E_mathrm{res}$, of kinetic energy related to the mean tangential equatorial velocity component, $M(overline{v_phi}^2/2$, to kineticenergy related to tangential equatorial component velocity dispersion, $Msigma_{phiphi}^2/2$, andresidual motions, $M(sigma_{ww}^2+sigma_{33}^2/2$.Without loss of generality (above a thresholdin ellipticity values, the analysis is restricted to systems with isotropic stress tensor, whichmay be considered as adjoint configurationsto any assigned homeoidally striated density profile with anisotropic stress tensor, different angular momentum, and equal remaining parameters.The description of configurations in the$({sf O}hat{e}chi_v^2$ plane is extendedin two respects, namely (a from equilibriumto nonequilibrium figures, where the virialequations hold with additional kinetic energy,and (b from real to imaginary rotation, wherethe effect is elongating instead of flattening,with respect to the rotation axis.An application is made toa subsample $(N=16$ of elliptical galaxies extracted from richer samples $(N=25,~N=48$of early type galaxies investigated within theSAURON project (Cappellari et al. 2006, 2007.Sample objects are idealized as homeoidallystriated MacLaurinspheroids and Jacobi ellipsoids, and theirposition in the $({sf O}hat{e}chi_v^2$plane is inferred from observations followinga procedure outlined in an earlier paper(Caimmi 2009b. The position of related adjoint configurations with isotropic stresstensor is also determined. With a singleexception (NGC 3379, slow rotators arecharacterized by low ellipticities $(0lehat{e}<0.2$, low anisotropy parameters$(0ledelta<0

  14. Effects of magnets with non-unit magnetic permeability on an elliptically polarizing undulator.

    Science.gov (United States)

    Wang, C; Chang, L H; Chang, C H; Lin, M C; Hwang, C S; Chen, J R

    1998-05-01

    This study employs the three-dimensional magnetostatic code TOSCA to assess numerically the effects of NdFeB magnets with non-unit magnetic permeability on an elliptically polarizing undulator. A reduction of a few percent of the on-axis magnetic field strength is predicted. In addition, a deviation of +/-100 G cm uncompensated dipole steering is predicted in a phase shift of 180 degrees for the elliptically polarizing undulator EPU5.6 (having a period length of 56 mm) at the minimum gap of 18 mm, which is related primarily to the configuration of the device end scheme. Results presented herein demonstrate that implementing an active compensation mechanism is a prerequisite for minimizing the orbit distortion during phase-shift adjustment, particularly for operating such a polarizing undulator in a third-generation machine having a median energy similar to that of the 1.5 GeV storage ring at SRRC.

  15. A Piezoelectric Screw Dislocation Interacting with an Elliptical Piezoelectric Inhomogeneity Containing a Confocal Elliptical Rigid Core

    Institute of Scientific and Technical Information of China (English)

    蒋纯志; 谢超; 刘又文

    2011-01-01

    The electro-elastic interaction between a piezoelectric screw dislocation and an elliptical piezoelectric inhomogeneity, which contains an electrically conductive confocal elliptical rigid core under remote anti-plane shear stresses and in-plane electrical load is dealt with. The anaJytical solutions to the elastic field and the electric field, the interracial stress fields of inhomogeneity and matrix under longitudinal shear and the image force acting on the dislocation are derived by means of complex method. The effect of material properties and geometric configurations of the rigid core on interracial stresses generated by a remote uniform load, rigid core and material electroelastic properties on the image force is discussed.

  16. Caloric curve of star clusters.

    Science.gov (United States)

    Casetti, Lapo; Nardini, Cesare

    2012-06-01

    Self-gravitating systems, such as globular clusters or elliptical galaxies, are the prototypes of many-body systems with long-range interactions, and should be the natural arena in which to test theoretical predictions on the statistical behavior of long-range-interacting systems. Systems of classical self-gravitating particles can be studied with the standard tools of equilibrium statistical mechanics, provided the potential is regularized at small length scales and the system is confined in a box. The confinement condition looks rather unphysical in general, so that it is natural to ask whether what we learn with these studies is relevant to real self-gravitating systems. In order to provide an answer to this question, we consider a basic, simple, yet effective model of globular clusters: the King model. This model describes a self-consistently confined system, without the need of any external box, but the stationary state is a nonthermal one. In particular, we consider the King model with a short-distance cutoff on the interactions, and we discuss how such a cutoff affects the caloric curve, i.e., the relation between temperature and energy. We find that the cutoff stabilizes a low-energy phase, which is absent in the King model without cutoff; the caloric curve of the model with cutoff turns out to be very similar to that of previously studied confined and regularized models, but for the absence of a high-energy gaslike phase. We briefly discuss the possible phenomenological as well as theoretical implications of these results.

  17. Measuring Shapes of Cosmological Images I Ellipticity and Orientation

    CERN Document Server

    Rahman, N A; Rahman, Nurur; Shandarin, Sergei F.

    2003-01-01

    We suggest a set of morphological measures that we believe can help in quantifying the shapes of two-dimensional cosmological images such as galaxies, clusters, and superclusters of galaxies. The method employs non-parametric morphological descriptors known as the Minkowski functionals in combination with geometric moments widely used in the image analysis. For the purpose of visualization of the morphological properties of contour lines we introduce three auxiliary ellipses representing the vector and tensor Minkowski functionals. We study the discreteness, seeing, and noise effects on elliptic contours as well as their morphological characteristics such as the ellipticity and orientation. In order to reduce the effect of noise we employ a technique of contour smoothing. We test the method by studying simulated elliptic profiles with various ellipticities ranging from E0 to E7 and illustrate the usefulness by measuring ellipticities and orientations of $K_s$ images of eight elliptics, three spirals and one p...

  18. Inverse Coefficient Problems for Nonlinear Elliptic Variational Inequalities

    Institute of Scientific and Technical Information of China (English)

    Run-sheng Yang; Yun-hua Ou

    2011-01-01

    This paper is devoted to a class of inverse coefficient problems for nonlinear elliptic variational inequalities. The unknown coefficient of elliptic variational inequalities depends on the gradient of the solution and belongs to a set of admissible coefficients. It is shown that the nonlinear elliptic variational inequalities is unique solvable for the given class of coefficients. The existence of quasisolutions of the inverse problems is obtained.

  19. The Evolution of Elliptic Flow Under First Order Phase Transition

    Institute of Scientific and Technical Information of China (English)

    冯启春; 王清尚; 刘剑利; 任延宇; 张景波; 霍雷

    2012-01-01

    Elliptic flow for non-central Au+Au collisions at √SNN=200 GeV is investigated with a 2+1 dimensional hydrodynamic model. We analyze the softening effect by the velocity along the axis. The contribution of the elliptic flow from the QGP phase, mixed phase and hadron gas phase is studied. The relation between the sound horizon and evolution of the elliptic flow is discussed.

  20. Quadrature Uncertainty and Information Entropy of Quantum Elliptical Vortex States

    OpenAIRE

    Banerji, Anindya; Panigrahi, Prasanta. K.; Singh, Ravindra Pratap; Chowdhury, Saurav; Bandyopadhyay, Abir

    2012-01-01

    We study the quadrature uncertainty of the quantum elliptical vortex state using the associated Wigner function. Deviations from the minimum uncertainty states were observed due to the absence of the Gaussian nature. In our study of the entropy, we noticed that with increasing vorticity, entropy increases for both the modes. We further observed that, there exists an optimum value of ellipticity which gives rise to maximum entanglement of the two modes of the quantum elliptical vortex states. ...

  1. Multiple sine, multiple elliptic gamma functions and rational cones

    CERN Document Server

    Tizzano, Luigi

    2015-01-01

    We define generalizations of the multiple elliptic gamma functions and the multiple sine functions, labelled by rational cones in $\\mathbb{R}^r$. For $r=2,3$ we prove that the generalized multiple elliptic gamma functions enjoy a modular property determined by the cone. This generalizes the modular properties of the elliptic gamma function studied by Felder and Varchenko. The generalized multiple sine enjoy a related infinite product representation, generalizing the results of Narukawa for the ordinary multiple sine functions.

  2. Gas-Phase Oxidation of Cm+ and Cm2+ -- Thermodynamics of neutral and ionized CmO

    Energy Technology Data Exchange (ETDEWEB)

    Gibson, John K; Haire, Richard G.; Santos, Marta; Pires de Matos, Antonio; Marcalo, Joaquim

    2008-12-08

    Fourier transform ion cyclotron resonance mass spectrometry was employed to study the products and kinetics of gas-phase reactions of Cm+ and Cm2+; parallel studies were carried out with La+/2+, Gd+/2+ and Lu+/2+. Reactions with oxygen-donor molecules provided estimates for the bond dissociation energies, D[M+-O](M = Cm, Gd, Lu). The first ionization energy, IE[CmO], was obtained from the reactivity of CmO+ with dienes, and the second ionization energies, IE[MO+](M = Cm, La, Gd, Lu), from the rates of electron-transfer reactions from neutrals to the MO2+ ions. The following thermodynamic quantities for curium oxide molecules were obtained: IE[CmO]= 6.4+-0.2 eV; IE[CmO+]= 15.8+-0.4 eV; D[Cm-O]= 710+-45 kJ mol-1; D[Cm+-O]= 670+-40 kJ mol-1; and D[Cm2+-O]= 342+-55 kJ mol-1. Estimates for the M2+-O bond energies for M = Cm, La, Gd and Lu are all intermediate between D[N2-O]and D[OC-O]--i.e., 167 kJ mol-1< D[M2+-O]< 532 kJ mol-1 -- such that the four MO2+ ions fulfill the thermodynamic requirement for catalytic O-atom transport from N2O to CO. It was demonstrated that the kinetics are also favorable and that the CmO2+, LaO2+, GdO2+ and LuO2+ dipositive ions each catalyze the gas-phase oxidation of CO to CO2 by N2O. The CmO2+ ion appeared during the reaction of Cm+ with O2 when the intermediate, CmO+, was not collisionally cooled -- although its formation is kinetically and/or thermodynamically unfavorable, CmO2+ is a stable species.

  3. 77 FR 8877 - ICD-9-CM Coordination and Maintenance (C&M) Committee Meeting

    Science.gov (United States)

    2012-02-15

    ... HUMAN SERVICES Centers for Disease Control and Prevention ICD-9-CM Coordination and Maintenance (C&M... Standards Staff, announces the following meeting. Name: ICD-9-CM Coordination and Maintenance (C&M... ), for questions about the registration process. Purpose: The ICD-9-CM Coordination and...

  4. THE MIXED PROBLEM FOR DEGENERATE ELLIPTIC EQUATIONS OF SECOND ORDER

    Institute of Scientific and Technical Information of China (English)

    Guochun Wen

    2005-01-01

    The present paper deals with the mixed boundary value problem for elliptic equations with degenerate rank 0. We first give the formulation of the problem and estimates of solutions of the problem, and then prove the existence of solutions of the above problem for elliptic equations by the above estimates and the method of parameter extension. We use the complex method, namely first discuss the corresponding problem for degenerate elliptic complex equations of first order, afterwards discuss the above problem for degenerate elliptic equations of second order.

  5. Heterodyne detector for measuring the characteristic of elliptically polarized microwaves

    DEFF Research Database (Denmark)

    Leipold, Frank; Nielsen, Stefan Kragh; Michelsen, Susanne

    2008-01-01

    In the present paper, a device is introduced, which is capable of determining the three characteristic parameters of elliptically polarized light (ellipticity, angle of ellipticity, and direction of rotation) for microwave radiation at a frequency of 110 GHz. The device consists of two...... be calculated. Results from measured and calculated wave characteristics of an elliptically polarized 110 GHz microwave beam for plasma heating launched into the TEXTOR-tokamak experiment are presented. Measurement and calculation are in good agreement. ©2008 American Institute of Physics...

  6. SOLVABILITY FOR NONLINEAR ELLIPTIC EQUATION WITH BOUNDARY PERTURBATION

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The solvability of nonlinear elliptic equation with boundary perturbation is considered. The perturbed solution of original problem is obtained and the uniformly valid expansion of solution is proved.

  7. Partial differential equations IX elliptic boundary value problems

    CERN Document Server

    Egorov, Yu; Shubin, M

    1997-01-01

    This EMS volume gives an overview of the modern theory of elliptic boundary value problems. The contribution by M.S. Agranovich is devoted to differential elliptic boundary problems, mainly in smooth bounded domains, and their spectral properties. This article continues his contribution to EMS 63. The contribution by A. Brenner and E. Shargorodsky concerns the theory of boundary value problems for elliptic pseudodifferential operators. Problems both with and without the transmission property, as well as parameter-dependent problems are considered. The article by B. Plamenevskij deals with general differential elliptic boundary value problems in domains with singularities.

  8. Note on twisted elliptic genus of K3 surface

    Energy Technology Data Exchange (ETDEWEB)

    Eguchi, Tohru, E-mail: eguchi@yukawa.kyoto-u.ac.j [Yukawa Institute for Theoretical Physics, Kyoto University, Kyoto 606-8502 (Japan); Hikami, Kazuhiro, E-mail: KHikami@gmail.co [Department of Mathematics, Naruto University of Education, Tokushima 772-8502 (Japan)

    2011-01-03

    We discuss the possibility of Mathieu group M{sub 24} acting as symmetry group on the K3 elliptic genus as proposed recently by Ooguri, Tachikawa and one of the present authors. One way of testing this proposal is to derive the twisted elliptic genera for all conjugacy classes of M{sub 24} so that we can determine the unique decomposition of expansion coefficients of K3 elliptic genus into irreducible representations of M{sub 24}. In this Letter we obtain all the hitherto unknown twisted elliptic genera and find a strong evidence of Mathieu moonshine.

  9. Colors of Ellipticals from GALEX to Spitzer

    Science.gov (United States)

    Schombert, James M.

    2016-12-01

    Multi-color photometry is presented for a large sample of local ellipticals selected by morphology and isolation. The sample uses data from the Galaxy Evolution Explorer (GALEX), Sloan Digital Sky Survey (SDSS), Two Micron All-Sky Survey (2MASS), and Spitzer to cover the filters NUV, ugri, JHK and 3.6 μm. Various two-color diagrams, using the half-light aperture defined in the 2MASS J filter, are very coherent from color to color, meaning that galaxies defined to be red in one color are always red in other colors. Comparison to globular cluster colors demonstrates that ellipticals are not composed of a single age, single metallicity (e.g., [Fe/H]) stellar population, but require a multi-metallicity model using a chemical enrichment scenario. Such a model is sufficient to explain two-color diagrams and the color-magnitude relations for all colors using only metallicity as a variable on a solely 12 Gyr stellar population with no evidence of stars younger than 10 Gyr. The [Fe/H] values that match galaxy colors range from -0.5 to +0.4, much higher (and older) than population characteristics deduced from Lick/IDS line-strength system studies, indicating an inconsistency between galaxy colors and line indices values for reasons unknown. The NUV colors have unusual behavior, signaling the rise and fall of the UV upturn with elliptical luminosity. Models with blue horizontal branch tracks can reproduce this behavior, indicating the UV upturn is strictly a metallicity effect.

  10. Velocity dispersion around ellipticals in MOND

    CERN Document Server

    Tiret, O; Angus, G W; Famaey, B; Zhao, H S

    2007-01-01

    We investigate how different models that have been proposed for solving the dark matter problem can fit the velocity dispersion observed around elliptical galaxies, on either a small scale (~ 20kpc) with stellar tracers, such as planetary nebulae, or large scale (~ 200kpc) with satellite galaxies as tracers. Predictions of Newtonian gravity, either containing pure baryonic matter, or embedded in massive cold dark matter (CDM) haloes, are compared with predictions of the modified gravity of MOND. The standard CDM model has problems on a small scale, and the Newtonian pure baryonic model has difficulties on a large scale, while a fit with MOND is possible on both scales.

  11. Three Dimensional Interface Problems for Elliptic Equations

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The author studies the structure of solutions to the interface problems for second order linear elliptic partial differential equations in three space dimension. The set of singular points consists of some singular lines and some isolated singular points. It is proved that near a singular line or a singular point, each weak solution can be decomposed into two parts, a singular part and a regular part. The singular parts are some finite sum of particular solutions to some simpler equations, and the regular parts are bounded in some norms, which are slightly weaker than that in the Sobolev space H2.

  12. Young circumnuclear disks in elliptical galaxies

    Science.gov (United States)

    Sil'Chenko, Olga K.

    2009-04-01

    By means of integral-field spectroscopy with the Multi-Pupil Field/Fiber Spectrograph of the Russian 6-m telescope we have studied the central parts of NGC 759 and NGC 83— regular (non-interacting, without strong nuclear activity) round red luminous ( M B =-20.8--21.6) elliptical galaxies which are however known to possess molecular gas. In both galaxies we have found central stellar disks with the extension of 1-2 kpc along the radius which are evidently being formed just now.

  13. Energy loss as the origin of an universal scaling law of the elliptic flow

    CERN Document Server

    Andrés, Carlota; Pajares, Carlos

    2016-01-01

    It is shown that the excellent scaling of the elliptic flow found for all centralities, species and energies from RHIC to the LHC for $p_{T}$ less than the saturation momentum is a consequence of the energy lost by a parton interacting with the color field produced in a nucleus-nucleus collision. In particular, the deduced shape of the scaling curve describes correctly all the data. We discuss the possible extensions to higher $p_{T}$, proton-nucleus and proton-proton collisions as well as higher harmonics.

  14. Application of multiquadric method for numerical solution of elliptic partial differential equations

    Energy Technology Data Exchange (ETDEWEB)

    Sharan, M. [Indian Inst. of Tech., New Delhi (India); Kansa, E.J. [Lawrence Livermore National Lab., CA (United States); Gupta, S. [Govt. Girls Sr. Sec. School I, Madangir, New Delhi (India)

    1994-01-01

    We have used the multiquadric (MQ) approximation scheme for the solution of elliptic partial differential equations with Dirichlet and/or Neumann boundary conditions. The scheme has the advantage to use the data points in arbitrary locations with an arbitrary ordering. Two dimensional Laplace, Poisson and Biharmonic equations describing the various physical processes, have been taken as the test examples. The agreement is found to be very good between the computed and exact solutions. The method also provides an excellent approximation with curve boundary.

  15. Energy loss as the origin of a universal scaling law of the elliptic flow

    Energy Technology Data Exchange (ETDEWEB)

    Andres, Carlota; Pajares, Carlos [Universidade de Santiago de Compostela, Instituto Galego de Fisica de Altas Enerxias IGFAE, Santiago de Compostela, Galicia (Spain); Braun, Mikhail [Saint Petersburg State University, Department of High-Energy Physics, Saint Petersburg (Russian Federation)

    2017-03-15

    It is shown that the excellent scaling of the elliptic flow found for all centralities, species and energies from RHIC to the LHC for p{sub T} less than the saturation momentum is a consequence of the energy lost by a parton interacting with the color field produced in a nucleus-nucleus collision. In particular, the deduced shape of the scaling curve describes correctly all the data. We discuss the possible extensions to higher p{sub T}, proton-nucleus and proton-proton collisions as well as higher harmonics. (orig.)

  16. Weak Elliptical Distortion of the Milky Way Potential traced by Open Clusters

    Institute of Scientific and Technical Information of China (English)

    Zi Zhu

    2008-01-01

    From photometric observations and star counts, the existence of a bar in the cen-tral few kpc of the Galaxy is suggested. It is generally thought that our Galaxy is surrounded by a massive invisible halo. The gravitational potential of the Galaxy is therefore made non-axisymmetric generated by the central tfiaxial bar, by the outer triaxial halo, and/or by the spiral structures. Selecting nearly 300 open clusters with complete spatial velocity measure-ments and ages, we were able to construct the rotation curve of the Milky Way within a range of 3 kpc of the Sun. Using a dynamic model for an assumed elliptical disk, a clear weak el-liptical potential of the disk with ellipticity of ε(R0) = 0.060 ± 0.012 is detected, the Sun is found to be near the minor axis, displaced by 30°± 3°. The motion of the clusters is suggested to be on an oval orbit rather than on a circular one.

  17. A Non-Zero Hadronic Elliptic Flow with a Vanished Partonic Elliptic Flow in a Coalescence Scenario

    Institute of Scientific and Technical Information of China (English)

    LIU Jian-Li; SHAN Lian-Qiang; FENG Qi-Chun; WU Feng-Juan; ZHANG Jing-Bo; TANG Gui-Xin; HUO Lei

    2009-01-01

    The elliptic flow of a hadron is calculated using a quark coalescence model based on the quark phase space distribution produced by a free streaming locally thermalized quark in a two-dimensional transverse plane at initial time. Without assuming the quark's elliptic flow, it is shown that the hadron obtains a non-zero elliptic flow in this model. The elliptic flow of the hadron is shown to be sensitive to both space momentum correlation and the hadron's internal structure. Quark number scaling is obtained only for some special cases.

  18. Spinal curves (image)

    Science.gov (United States)

    There are four natural curves in the spinal column. The cervical, thoracic, lumbar, and sacral curvature. The curves, along with the intervertebral disks, help to absorb and distribute stresses that occur from everyday activities such as walking or from ...

  19. Contractibility of curves

    Directory of Open Access Journals (Sweden)

    Janusz Charatonik

    1991-11-01

    Full Text Available Results concerning contractibility of curves (equivalently: of dendroids are collected and discussed in the paper. Interrelations tetween various conditions which are either sufficient or necessary for a curve to be contractible are studied.

  20. Parametrizing Algebraic Curves

    OpenAIRE

    Lemmermeyer, Franz

    2011-01-01

    We present the technique of parametrization of plane algebraic curves from a number theorist's point of view and present Kapferer's simple and beautiful (but little known) proof that nonsingular curves of degree > 2 cannot be parametrized by rational functions.

  1. Thermodynamics of Inozemtsev's elliptic spin chain

    Science.gov (United States)

    Klabbers, Rob

    2016-06-01

    We study the thermodynamic behaviour of Inozemtsev's long-range elliptic spin chain using the Bethe ansatz equations describing the spectrum of the model in the infinite-length limit. We classify all solutions of these equations in that limit and argue which of these solutions determine the spectrum in the thermodynamic limit. Interestingly, some of the solutions are not selfconjugate, which puts the model in sharp contrast to one of the model's limiting cases, the Heisenberg XXX spin chain. Invoking the string hypothesis we derive the thermodynamic Bethe ansatz equations (TBA-equations) from which we determine the Helmholtz free energy in thermodynamic equilibrium and derive the associated Y-system. We corroborate our results by comparing numerical solutions of the TBA-equations to a direct computation of the free energy for the finite-length hamiltonian. In addition we confirm numerically the interesting conjecture put forward by Finkel and González-López that the original and supersymmetric versions of Inozemtsev's elliptic spin chain are equivalent in the thermodynamic limit.

  2. Hadronic Transport Effects on Elliptic Flow

    Institute of Scientific and Technical Information of China (English)

    李娜; 施梳苏

    2011-01-01

    Elliptic flow v2 is considered as a probe to study partonic collectivity,and the measurement v2/e can be used to describe the hydro behavior of the colliding system.We study the the effect of the hadronic process on the momentum anisotropy parameter v2 in a multiphase transport model.It is found that hadronic rescattering will depress the v2 signal built up at the partonic phase.A similar mass hierarchy is observed in the model as in the experiment at RHIC.We find that different particle species will approach the same ideal hydro limit if the hadronic process is excluded.%Elliptic Bow V2 is considered as a probe to study partonic collectivity, and the measurement V2/S can be used to describe the hydro behavior of the colliding system. We study the the effect of the hadronic process on the momentum anisotropy parameter vi in a multiphase transport model. It is found that hadronic rescattering will depress the V2 signal built up at the partonic phase. A similar mass hierarchy is observed in the model as in the experiment at RHIC. We find that different particle species will approach the same ideal hydro limit if the hadronic process is excluded.

  3. The Ellipticity Distribution of Ambiguously Blended Objects

    CERN Document Server

    Dawson, William A; Tyson, J Anthony; Jee, M James

    2014-01-01

    Using overlapping fields with space-based Hubble Space Telescope (HST) and ground-based Subaru Telescope imaging we identify a population of blended galaxies that would not be easily distinguished with ground-based monochromatic imaging alone, which we label as 'ambiguous blends'. For the depth targeted with the Large Synoptic Survey Telescope (LSST), the ambiguous blend population is both large (~14%) and has a distribution of ellipticities that is markedly different from that of unblended objects in a way that will likely be important for the weak lensing measurements. Most notably, we find that ambiguous blending results in a ~14% increase in shear noise (or ~12% decrease in the effective number density of galaxies, $n_{eft}$) due to 1) larger intrinsic ellipticity dispersion, 2) a scaling with the galaxy number density $N_{gal}$ that is shallower than 1/$\\sqrt{N_{gal}}$. For the LSST Gold Sample (i<25.3) there is a $\\sim$7\\% increase in shear noise (or ~7% decrease in $n_{eff}$)

  4. Colors of Ellipticals from GALEX to Spitzer

    CERN Document Server

    Schombert, J

    2016-01-01

    Multi-color photometry is presented for a large sample of local ellipticals selected by morphology and isolation. The sample uses data from GALEX, SDSS, 2MASS and Spitzer to cover the filters NUV, ugri, JHK and 3.6mum. Various two-color diagrams, using the half-light aperture defined in the 2MASS J filter, are very coherent from color to color, meaning that galaxies defined to be red in one color are always red in other colors. Comparison to globular cluster colors demonstrates that ellipticals are *not* composed of a single age, single metallicity (e.g., [Fe/H]) stellar population, but require a multi-metallicity model using a chemical enrichment scenario. Such a model is sufficient to explain two-color diagrams and the color-magnitude relations for all colors using only metallicity as a variable on a solely 12 Gyrs stellar population with no evidence of stars younger than 10 Gyrs. The [Fe/H] values that match galaxy colors range from -0.5 to +0.4, much higher (and older) than population characteristics dedu...

  5. Picone-type inequalities for nonlinear elliptic equations and their applications

    Directory of Open Access Journals (Sweden)

    Takaŝi Kusano

    2001-01-01

    Full Text Available Picone-type inequalities are derived for nonlinear elliptic equations, and Sturmian comparison theorems are established as applications. Oscillation theorems for forced super-linear elliptic equations and superlinear-sublinear elliptic equations are also obtained.

  6. Expansion Velocity Investigation of the Elliptical Planetary Nebula NGC 6803

    Science.gov (United States)

    Choi, Younsu Choi; Lee, Seong-Jae; Hyung, Siek

    2008-12-01

    Using the spectral data in the 3700 to 10050 Å wavelength range secured with the Hamilton Echelle Spectrograph (HES) at the Lick observatory, we have investigated the expansion velocities and the physical conditions of the elliptical planetary nebula NGC 6803. Various forbidden and permitted lines, e.g. HI, HeI, HeII, [OIII], [NII], [ArIII], and [SII], indicate complicated but systematic physical conditions variation: electron temperatures T_{ɛ} ˜ 9000 - 11,000 K and electron number densities N_{ɛ} ˜ 2000 - 9000 cm^{-3}. The line profile analysis of these ions also indicates the systematic change or the acceleration of the expansion velocities in the range of 10 - 22 kms. We show that the velocity gradient and physical condition found in various ions are closely related to the prolate ellipsoidal structure of NGC 6803. The expansion velocity and the ionic abundance of O^{2+} were derived based on the OII and [OIII] lines. In spite of the discrepancy of ionic abundances derived by the two cases and their line profiles, the expansion velocities of them agree well. We find that the ratios of the red to blue line component of the HeII & OII lines are different from those of the [OIII] or other forbidden lines that indicates a possible involvement of emission of HeII & OII lines. This subtle difference and the different physical condition of the lines are likely to be caused by the elongated geometry and the latitude dependence of the emission zone.

  7. Propagating Characteristics of Confocal Elliptical Waveguide Filled with Multilayered Dielectrics

    Institute of Scientific and Technical Information of China (English)

    熊天信; 杨儒贵

    2004-01-01

    Using the method of separation of variables in the elliptical coordinate system, a recursive formula for the electromagnetic fields in a confocal elliptical waveguide filled with multi-layered homogeneous isotropic media is derived; then the eigenequation for it is given. When an elliptical waveguide becomes a circular waveguide, the electromagnetic fields and the eigenequation of the circular waveguide can be obtained from the eigenequation of the elliptical waveguide using the asymptotic formulae of Mathieu and modified Mathieu functions for a large radial coordinate in the elliptical coordinate system, and the eigenequation of a circular waveguide filled with multilayered dielectrics can be treated as a special case of an elliptical waveguide.In addition, some numerical examples are presented to analyze the propagating characteristics influenced by the permittivity, permeability of dielectrics filled in the elliptical waveguide, etc. The results show that changing the permittivity or permeability of the dielectrics filled in the waveguide and the major semiaxis value of the i-th layer can change the propagating characteristics of an elliptical waveguide.

  8. Effect of the earth's ellipticity on the lunar tidal potential

    Science.gov (United States)

    Dahlen, F. A.

    1993-01-01

    The earth's orbital acceleration about the moon is influenced by its ellipticity. In this paper it shown that the ellipticity affects tidal gravity by contributing directly to the lunar tide-generating potential (in addition to effecting the elastic-gravitational response of the solid earth and oceans to this potential).

  9. QUASILINEAR ELLIPTIC BOUNDARY VALUE PROBLEMS WITH DISCONTINUOUS NONLINEARITIES

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    In this paper we shall consider a discontinuous nonlinear nonmonotone elliptic boundary value problem, i.e. a quasilinear elliptic hemivariational inequality. This kind of problems is strongly motivated by various problems in mechanics. By use of the notion of the generalized gradient of Clarke and the theory of pseudomonotone operators, we will prove the existence of solutions.

  10. Exact Jacobian Elliptic Function Solutions to sinh-Gordon Equation

    Institute of Scientific and Technical Information of China (English)

    FU Zun-Tao; LIU Shi-Kuo; LIU Shi-Da

    2006-01-01

    In this paper, two transformations are introduced to solve sinh-Gordon equation by using the knowledge of elliptic equation and Jacobian elliptic functions.It is shown that different transformations are required in order to obtain more kinds of solutions to the sinh-Gordon equation.

  11. Free Fermionic Elliptic Reflection Matrices and Quantum Group Invariance

    CERN Document Server

    Cuerno, R

    1993-01-01

    Elliptic diagonal solutions for the reflection matrices associated to the elliptic $R$ matrix of the eight vertex free fermion model are presented. They lead through the second derivative of the open chain transfer matrix to an XY hamiltonian in a magnetic field which is invariant under a quantum deformed Clifford--Hopf algebra.

  12. Free Boundary Value Problems for Abstract Elliptic Equations and Applications

    Institute of Scientific and Technical Information of China (English)

    Veli SHAKHMUROV

    2011-01-01

    The free boundary value problems for elliptic differential-operator equations are studied.Several conditions for the uniform maximal regularity with respect to boundary parameters and the Fredholmness in abstract Lp-spaces are given.In application,the nonlocal free boundary problems for finite or infinite systems of elliptic and anisotropic type equations are studied.

  13. Elliptic Equation and New Solutions to Nonlinear Wave Equations

    Institute of Scientific and Technical Information of China (English)

    FU Zun-Tao; LIU Shi-Kuo; LIU Shi-Da

    2004-01-01

    The new solutions to elliptic equation are shown, and then the elliptic equation is taken as a transformationand is applied to solve nonlinear wave equations. It is shown that more kinds of solutions are derived, such as periodicsolutions of rational form, solitary wave solutions of rational form, and so on.

  14. THz and infrared metamaterial polarization converter with tunable ellipticity

    DEFF Research Database (Denmark)

    Markovich, D. L.; Andryieuski, Andrei; Lavrinenko, Andrei

    2012-01-01

    In this contribution we present the metamaterial based polarization converter from linear to elliptical polarization with a desired ellipticity and ellipse orientation. We show two designs with the conversion efficiency 50% for the frequencies around 1 THz and 193 THz. The proposed device is real...

  15. CM: Becoming a technology firm (teaching case)

    NARCIS (Netherlands)

    Burg, van J.C.; Reymen, I.M.M.J.; Dolmans, S.A.M.

    2011-01-01

    Founded in 2000 as a Short Message Service (SMS) marketing company for discos (clubs), CM evolved into a technology provider for SMS services. By 2008, CM was market leader in The Netherlands, a position won by offering high quality services at low prices. In 2010, the founders of the company were l

  16. Elliptic Curves, Algebraic Geometry Approach in Gravity Theory and Uniformization of Multivariable Cubic Algebraic Equations

    OpenAIRE

    2008-01-01

    Based on the distinction between the covariant and contravariant metric tensor components in the framework of the affine geometry approach and the s.c. "gravitational theories with covariant and contravariant connection and metrics", it is shown that a wide variety of third, fourth, fifth, seventh, tenth- degree algebraic equations exists in gravity theory. This is important in view of finding new solutions of the Einstein's equations, if they are treated as algebraic ones. Since the obtained...

  17. Analysis and Enhancement of a Password Authentication and Update Scheme Based on Elliptic Curve Cryptography

    Directory of Open Access Journals (Sweden)

    Lili Wang

    2014-01-01

    Full Text Available Recently, a password authentication and update scheme has been presented by Islam and Biswas to remove the security weaknesses in Lin and Huang’s scheme. Unfortunately, He et al., Wang et al., and Li have found out that Islam and Biswas’ improvement was vulnerable to offline password guessing attack, stolen verifier attack, privilege insider attack, and denial of service attack. In this paper, we further analyze Islam and Biswas’ scheme and demonstrate that their scheme cannot resist password compromise impersonation attack. In order to remedy the weaknesses mentioned above, we propose an improved anonymous remote authentication scheme using smart card without using bilinear paring computation. In addition, the verifier tables are no longer existent, and the privacy of users could be protected better. Furthermore, our proposal not only inherits the advantages in Islam and Biswas’ scheme, but also provides more features, including preserving user anonymity, supporting offline password change, revocation, reregistration with the same identifier, and system update. Finally, we compare our enhancement with related works to illustrate that the improvement is more secure and robust, while maintaining low performance cost.

  18. Design of elliptic curve cryptoprocessors over GF(2^163) using the Gaussian normal basis

    OpenAIRE

    Paulo Cesar Realpe; Vladimir Trujillo-Olaya; Jaime Velasco-Medina

    2014-01-01

    En este trabajo se presenta la implementación eficiente en hardware de criptoprocesadores que permiten llevar a cabo la multiplicación escalar kP sobre el campo finito GF(2163) usando dos multiplicadores a nivel de digito. Las operaciones aritméticas de campo finito fueron implementadas usando la representación de bases normales Gaussianas (GNB), y la multiplicación escalar kP fue implementada usando el algoritmo de López-Dahab, el algoritmo de bisección de punto 2-NAF y el método w-tNAF para...

  19. Cryptanalysis of an Efficient Signcryption Scheme with Forward Secrecy Based on Elliptic Curve

    CERN Document Server

    Toorani, Mohsen; 10.1109/ICCEE.2008.147

    2010-01-01

    The signcryption is a relatively new cryptographic technique that is supposed to fulfill the functionalities of encryption and digital signature in a single logical step. Several signcryption schemes are proposed throughout the years, each of them having its own problems and limitations. In this paper, the security of a recent signcryption scheme, i.e. Hwang et al.'s scheme is analyzed, and it is proved that it involves several security flaws and shortcomings. Several devastating attacks are also introduced to the mentioned scheme whereby it fails all the desired and essential security attributes of a signcryption scheme.

  20. Area Efficient Hardware Implementation of Elliptic Curve Cryptography by Iteratively Applying Karatsuba's Method

    CERN Document Server

    Dyka, Zoya

    2011-01-01

    Securing communication channels is especially needed in wireless environments. But applying cipher mechanisms in software is limited by the calculation and energy resources of the mobile devices. If hardware is applied to realize cryptographic operations cost becomes an issue. In this paper we describe an approach which tackles all these three points. We implemented a hardware accelerator for polynomial multiplication in extended Galois fields (GF) applying Karatsuba's method iteratively. With this approach the area consumption is reduced to 2.1 mm^2 in comparison to. 6.2 mm^2 for the standard application of Karatsuba's method i.e. for recursive application. Our approach also reduces the energy consumption to 60 per cent of the original approach. The price we have to pay for these achievement is the increased execution time. In our implementation a polynomial multiplication takes 3 clock cycles whereas the recurisve Karatsuba approach needs only one clock cycle. But considering area, energy and calculation sp...

  1. On the Adoption of the Elliptic Curve Digital Signature Algorithm (ECDSA) in DNSSEC

    NARCIS (Netherlands)

    van Rijswijk, Roland M.; Jonker, Mattijs; Sperotto, Anna

    2016-01-01

    The Domain Name System Security Extensions (DNSSEC) are steadily being deployed across the Internet. DNSSEC extends the DNS protocol with two vital security properties, authenticity and integrity, using digital signatures. While DNSSEC is meant to solve security issues in the DNS, it also introduces

  2. A secured authentication protocol for wireless sensor networks using elliptic curves cryptography.

    Science.gov (United States)

    Yeh, Hsiu-Lien; Chen, Tien-Ho; Liu, Pin-Chuan; Kim, Tai-Hoo; Wei, Hsin-Wen

    2011-01-01

    User authentication is a crucial service in wireless sensor networks (WSNs) that is becoming increasingly common in WSNs because wireless sensor nodes are typically deployed in an unattended environment, leaving them open to possible hostile network attack. Because wireless sensor nodes are limited in computing power, data storage and communication capabilities, any user authentication protocol must be designed to operate efficiently in a resource constrained environment. In this paper, we review several proposed WSN user authentication protocols, with a detailed review of the M.L Das protocol and a cryptanalysis of Das' protocol that shows several security weaknesses. Furthermore, this paper proposes an ECC-based user authentication protocol that resolves these weaknesses. According to our analysis of security of the ECC-based protocol, it is suitable for applications with higher security requirements. Finally, we present a comparison of security, computation, and communication costs and performances for the proposed protocols. The ECC-based protocol is shown to be suitable for higher security WSNs.

  3. A Multiserver Biometric Authentication Scheme for TMIS using Elliptic Curve Cryptography.

    Science.gov (United States)

    Chaudhry, Shehzad Ashraf; Khan, Muhammad Tawab; Khan, Muhammad Khurram; Shon, Taeshik

    2016-11-01

    Recently several authentication schemes are proposed for telecare medicine information system (TMIS). Many of such schemes are proved to have weaknesses against known attacks. Furthermore, numerous such schemes cannot be used in real time scenarios. Because they assume a single server for authentication across the globe. Very recently, Amin et al. (J. Med. Syst. 39(11):180, 2015) designed an authentication scheme for secure communication between a patient and a medical practitioner using a trusted central medical server. They claimed their scheme to extend all security requirements and emphasized the efficiency of their scheme. However, the analysis in this article proves that the scheme designed by Amin et al. is vulnerable to stolen smart card and stolen verifier attacks. Furthermore, their scheme is having scalability issues along with inefficient password change and password recovery phases. Then we propose an improved scheme. The proposed scheme is more practical, secure and lightweight than Amin et al.'s scheme. The security of proposed scheme is proved using the popular automated tool ProVerif.

  4. Universal adelic groups for imaginary quadratic number fields and elliptic curves

    NARCIS (Netherlands)

    Angelakis, Athanasios

    2015-01-01

    The 1st chapter is of an introductory nature. It discusses the basic invariants of algebraic number fields and asks whether or to which extent such invariants characterize the number field. It surveys some of the older results in the area before focusing on the case of absolute abelian Galois groups

  5. On the Adoption of the Elliptic Curve Digital Signature Algorithm (ECDSA) in DNSSEC

    NARCIS (Netherlands)

    Rijswijk-Deij, van Roland; Jonker, Mattijs; Sperotto, Anna

    2016-01-01

    The Domain Name System Security Extensions (DNSSEC) are steadily being deployed across the Internet. DNSSEC extends the DNS protocol with two vital security properties, authenticity and integrity, using digital signatures. While DNSSEC is meant to solve security issues in the DNS, it also introduces

  6. Topology of algebraic curves an approach via dessins d'enfants

    CERN Document Server

    Degtyarev, Alex

    2012-01-01

    The book summarizes the state and new results on the topology of trigonal curves in geometrically ruled surfaces. Emphasis is placed upon various applications of the theory to related areas, most notably singularplane curves of small degree, elliptic surfaces, and Lefschetz fibrations (both complex and real), and Hurwitz equivalence of braid monodromy factorizations. The monograph conveys recent knowledge about related objects and is of interest to researchers and graduate students in the fields of topology and of complex and real algebraic varieties.

  7. Dynamic susceptibility of onion in ferromagnetic elliptical nanoring

    Science.gov (United States)

    Mu, Congpu; Song, Jiefang; Xu, Jianghong; Wen, Fusheng

    2016-06-01

    Micromagnetic simulation was performed to investigate the equilibrium state and dynamic susceptibility spectra of magnetic elliptical nanoring. There are two equilibrium states (onion and vortex) obtained in elliptical nanoring. The onion state can be used to record information in MRAM. And it is important to investigate the dynamic susceptibility spectra of onion state, which is closely related to writing and reading speed of magnetic memory devices. Those results show that two or three resonance peaks are found under different thickness of elliptical nanoring with onion state, respectively. The low resonance frequency of two resonance peaks is increasing with the arm width of the elliptical ring, but is decreasing with the thickness. However, the high frequency of two resonance peaks is decreasing with the arm width of the elliptical ring.

  8. Dynamic susceptibility of onion in ferromagnetic elliptical nanoring

    Directory of Open Access Journals (Sweden)

    Congpu Mu

    2016-06-01

    Full Text Available Micromagnetic simulation was performed to investigate the equilibrium state and dynamic susceptibility spectra of magnetic elliptical nanoring. There are two equilibrium states (onion and vortex obtained in elliptical nanoring. The onion state can be used to record information in MRAM. And it is important to investigate the dynamic susceptibility spectra of onion state, which is closely related to writing and reading speed of magnetic memory devices. Those results show that two or three resonance peaks are found under different thickness of elliptical nanoring with onion state, respectively. The low resonance frequency of two resonance peaks is increasing with the arm width of the elliptical ring, but is decreasing with the thickness. However, the high frequency of two resonance peaks is decreasing with the arm width of the elliptical ring.

  9. Quadrature Uncertainty and Information Entropy of Quantum Elliptical Vortex States

    CERN Document Server

    Banerji, Anindya; Singh, Ravindra Pratap; Chowdhury, Saurav; Bandyopadhyay, Abir

    2013-01-01

    We study the quadrature uncertainty of the quantum elliptical vortex state using the associated Wigner function. Deviations from the minimum uncertainty states were observed due to the absence of the Gaussian nature. In our study of the entropy, we noticed that with increasing vorticity, entropy increases for both the modes. We further observed that, there exists an optimum value of ellipticity which gives rise to maximum entanglement of the two modes of the quantum elliptical vortex states. A further increase in ellipticity reduces the entropy thereby resulting in a loss of information carrying capacity. We check the validity of the entropic inequality relations, namely the subaddivity and the Araki-Lieb inequality. The later was satisfied only for a very small range of the ellipticity of the vortex while the former seemed to be valid at all values.

  10. Multipacting studies in elliptic SRF cavities

    Science.gov (United States)

    Prakash, Ram; Jana, Arup Ratan; Kumar, Vinit

    2017-09-01

    Multipacting is a resonant process, where the number of unwanted electrons resulting from a parasitic discharge rapidly grows to a larger value at some specific locations in a radio-frequency cavity. This results in a degradation of the cavity performance indicators (e.g. the quality factor Q and the maximum achievable accelerating gradient Eacc), and in the case of a superconducting radiofrequency (SRF) cavity, it leads to a quenching of superconductivity. Numerical simulations are essential to pre-empt the possibility of multipacting in SRF cavities, such that its design can be suitably refined to avoid this performance limiting phenomenon. Readily available computer codes (e.g.FishPact, MultiPac,CST-PICetc.) are widely used to simulate the phenomenon of multipacting in such cases. Most of the contemporary two dimensional (2D) codes such as FishPact, MultiPacetc. are unable to detect the multipacting in elliptic cavities because they use a simplistic secondary emission model, where it is assumed that all the secondary electrons are emitted with same energy. Some three-dimensional (3D) codes such as CST-PIC, which use a more realistic secondary emission model (Furman model) by following a probability distribution for the emission energy of secondary electrons, are able to correctly predict the occurrence of multipacting. These 3D codes however require large data handling and are slower than the 2D codes. In this paper, we report a detailed analysis of the multipacting phenomenon in elliptic SRF cavities and development of a 2D code to numerically simulate this phenomenon by employing the Furman model to simulate the secondary emission process. Since our code is 2D, it is faster than the 3D codes. It is however as accurate as the contemporary 3D codes since it uses the Furman model for secondary emission. We have also explored the possibility to further simplify the Furman model, which enables us to quickly estimate the growth rate of multipacting without

  11. Investigating the Density of Isolated Field Elliptical Galaxies

    Science.gov (United States)

    Ulgen, E. Kaan

    2016-02-01

    In this thesis, 215.590 elliptical galaxies with M(r) ≤ -21 in the CFHTLS-W1 field which is covering 72 sq. deg on the sky are examined . Criterion given by Smith et al. (2004) has been used to determine isolated elliptical galaxies. 118 isolated elliptical galaxies have been determined in total. By using g, r and i photometric bands, the true-colour images of candidates are produced and visually inspected. In order to have a clean list of IfEs some candidates are excluded from the final sample after visual inspection. The final sample consists of 60 IfEs which corresponds to the 0.027 per cent of the whole sample. In other words, IfE density in the W1 is 0.8 IfE / sq.deg. Since the formation of the ellipticals in the isolated regions is not known clearly, it is crucial to determine IfEs and compare their photometric and morphological properties to the normal or cluster ellipticals. When the (g-i) distributions of three different elliptical galaxy class are compared, it is found that they have almost the same colours. When the redshift distributions of the galaxies are considered, it can be seen that IfEs formed later than the cluster and normal ellipticals. The average redshift of IfEs is determined as zphot=0.284, while for normal and cluster ellipticals, it is, respectively, 0.410 and 0.732. In addition, when the effective radii of the three elliptical systems are considered, it is found that the IfEs are bigger than the other two elliptical classes.

  12. Three-particle integrable systems with elliptic dependence on momenta and theta function identities

    Energy Technology Data Exchange (ETDEWEB)

    Aminov, G., E-mail: aminov@itep.ru [Institute of Theoretical and Experimental Physics, Moscow (Russian Federation); Moscow Institute of Physics and Technology, Dolgoprudny (Russian Federation); Mironov, A., E-mail: mironov@itep.ru [Institute of Theoretical and Experimental Physics, Moscow (Russian Federation); Theory Department, Lebedev Physics Institute, Moscow (Russian Federation); Morozov, A., E-mail: morozov@itep.ru [Institute of Theoretical and Experimental Physics, Moscow (Russian Federation); Zotov, A., E-mail: zotov@itep.ru [Institute of Theoretical and Experimental Physics, Moscow (Russian Federation); Moscow Institute of Physics and Technology, Dolgoprudny (Russian Federation); Steklov Mathematical Institute, Russian Academy of Sciences, Moscow (Russian Federation)

    2013-11-04

    We claim that some non-trivial theta-function identities at higher genus can stand behind the Poisson commutativity of the Hamiltonians of elliptic integrable systems, which were introduced in [1,2] and are made from the theta-functions on Jacobians of the Seiberg–Witten curves. For the case of three-particle systems the genus-2 identities are found and presented in the Letter. The connection with the Macdonald identities is established. The genus-2 theta-function identities provide the direct way to construct the Poisson structure in terms of the coordinates on the Jacobian of the spectral curve and the elements of its period matrix. The Lax representations for the two-particle systems are also obtained.

  13. Three-particle Integrable Systems with Elliptic Dependence on Momenta and Theta Function Identities

    CERN Document Server

    Aminov, G; Morozov, A; Zotov, A

    2013-01-01

    We claim that some non-trivial theta-function identities at higher genus can stand behind the Poisson commutativity of the Hamiltonians of elliptic integrable systems, which are made from the theta-functions on Jacobians of the Seiberg-Witten curves. For the case of three-particle systems the genus-2 identities are found and presented in the paper. The connection with the Macdonald identities is established. The genus-2 theta-function identities provide the direct way to construct the Poisson structure in terms of the coordinates on the Jacobian of the spectral curve and the elements of its period matrix. The Lax representations for the two-particle systems are also obtained.

  14. Rayleigh waves ellipticity and mode mis-identification in multi-channel analysis of surface waves

    DEFF Research Database (Denmark)

    Boaga, Jacopo; Cassiani, Giorgio; Strobbia, Claudio

    dispersion curve which is then inverted. Typically, single component vertical and multi channel receivers are used. In most cases the inversion of the dispersion properties is carried out assuming that the experimental dispersion curve corresponds to a single mode, mostly the fundamental Rayleigh mode......-identification known as ‘osculation’ (‘kissing’). In general it is called ‘osculation point’ the point where the energy peak shifts at low frequencies from the fundamental to the first higher mode. This jump occurs, with a continuous smooth transition, around a well-define frequency where the two modes get very close...... the vertical component of ground motion, as the mode osculation is linked to the Rayleigh wave ellipticity polarization, and therefore we conclude that multi-component data, using also horizontal receivers, can help discern the multi-modal nature of surface waves. Finally we introduce a-priori detectors...

  15. Winding light beams along elliptical helical trajectories

    CERN Document Server

    Wen, Yuanhui; Zhang, Yanfeng; Chen, Hui; Yu, Siyuan

    2016-01-01

    Conventional caustic methods in real or Fourier space produced accelerating optical beams only with convex trajectories. We develop a superposition caustic method capable of winding light beams along non-convex trajectories. We ascertain this method by constructing a one-dimensional (1D) accelerating beam moving along a sinusoidal trajectory, and subsequently extending to two-dimensional (2D) accelerating beams along arbitrarily elliptical helical trajectories. We experimentally implement the method with a compact and robust integrated optics approach by fabricating micro-optical structures on quartz glass plates to perform the spatial phase and amplitude modulation to the incident light, generating beam trajectories highly consistent with prediction. The theoretical and implementation methods can in principle be extended to the construction of accelerating beams with a wide variety of non-convex trajectories, thereby opening up a new route of manipulating light beams for fundamental research and practical ap...

  16. Globular Cluster System erosion in elliptical galaxies

    CERN Document Server

    Capuzzo-Dolcetta, Roberto

    2009-01-01

    In this paper we analyze data of 8 elliptical galaxies in order to study the difference between their globular cluster systems (GCSs) radial distributions and those of the galactic stellar component. In all the galaxies studied here the globular cluster system density profile is significantly flatter toward the galactic centre than that of stars. If this difference is interpreted as a depauperation of the initial GC population, the estimated number of missing globular clusters is significant, ranging from 21% to 71% of their initial population abundance in the eight galaxies examined. The corresponding mass lost to the central galactic region is 7x10^7-1.85x10^9 solar masses. All this mass carried toward central galactic regions have likely had an important feedback on the innermost galactic region, including its violent transient activity (AGN) and local massive black hole formation and growth.

  17. Aeroacoustic properties of supersonic elliptic jets

    Science.gov (United States)

    Kinzie, Kevin W.; McLaughlin, Dennis K.

    1999-09-01

    The aerodynamic and acoustic properties of supersonic elliptic and circular jets are experimentally investigated. The jets are perfectly expanded with an exit Mach number of approximately 1.5 and are operated in the Reynolds number range of 25 000 to 50 000. The reduced Reynolds number facilitates the use of conventional hot-wire anemometry and a glow discharge excitation technique which preferentially excites the varicose or flapping modes in the jets. In order to simulate the high-velocity and low-density effects of heated jets, helium is mixed with the air jets. This allows the large-scale structures in the jet shear layer to achieve a high enough convective velocity to radiate noise through the Mach wave emission process.

  18. Applications of Elliptic Integral and Elliptic Function to Electric Power Cable Problems

    Science.gov (United States)

    Watanabe, Kazuo

    The paper proposes an application of elliptic function to a new measuring method of electric resistivity of outer-semiconductive layer of XLPE cable. The new measuring method may substitute the conventional method. The resistivity can be obtained easily by measuring resistance between two electrodes which are attached to a circumferential edge on one side of the outer-semiconductive layer of a cable core sample. The solution process is applicable to heat conduction as well as hydromechanics.

  19. PURCELL EFFECT IN EXTREMELY ANISOTROPIC ELLIPTIC METAMATERIALS

    Directory of Open Access Journals (Sweden)

    Alexander V. Chebykin

    2014-11-01

    Full Text Available The paper deals with theoretical demonstration of Purcell effect in extremely anisotropic metamaterials with elliptical isofrequency surface. This effect is free from association with divergence in density of states unlike the case of hyperbolic metamaterials. It is shown that a large Purcell factor can be observed without excitation of modes with large wave vectors in one direction, and the component of the wave vector normal to the layers is less than k0. For these materials the possibility is given for increasing of the power radiated in the medium, as well as the power radiated from material into free space across the medium border situated transversely to the layers. We have investigated isofrequency contours and the dependence of Purcell factor from the frequency for infinite layered metamaterial structure. In the visible light range strong spatial dispersion gives no possibility to obtain enhancement of spontaneous emission in metamaterial with unit cell which consists of two layers. This effect can be achieved in periodic metal-dielectric layered nanostructures with a unit cell containing two different metallic layers and two dielectric ones. Analysis of the dependences for Purcell factor from the frequency shows that the spontaneous emission is enhanced by a factor of ten or more only for dipole orientation along metamaterial layers, but in the case of the transverse orientation radiation can be enhanced only 2-3 times at most. The results can be used to create a new type of metamaterials with elliptical isofrequency contours, providing a more efficient light emission in the far field.

  20. Modeling and Fitting Exoplanet Transit Light Curves

    Science.gov (United States)

    Millholland, Sarah; Ruch, G. T.

    2013-01-01

    We present a numerical model along with an original fitting routine for the analysis of transiting extra-solar planet light curves. Our light curve model is unique in several ways from other available transit models, such as the analytic eclipse formulae of Mandel & Agol (2002) and Giménez (2006), the modified Eclipsing Binary Orbit Program (EBOP) model implemented in Southworth’s JKTEBOP code (Popper & Etzel 1981; Southworth et al. 2004), or the transit model developed as a part of the EXOFAST fitting suite (Eastman et al. in prep.). Our model employs Keplerian orbital dynamics about the system’s center of mass to properly account for stellar wobble and orbital eccentricity, uses a unique analytic solution derived from Kepler’s Second Law to calculate the projected distance between the centers of the star and planet, and calculates the effect of limb darkening using a simple technique that is different from the commonly used eclipse formulae. We have also devised a unique Monte Carlo style optimization routine for fitting the light curve model to observed transits. We demonstrate that, while the effect of stellar wobble on transit light curves is generally small, it becomes significant as the planet to stellar mass ratio increases and the semi-major axes of the orbits decrease. We also illustrate the appreciable effects of orbital ellipticity on the light curve and the necessity of accounting for its impacts for accurate modeling. We show that our simple limb darkening calculations are as accurate as the analytic equations of Mandel & Agol (2002). Although our Monte Carlo fitting algorithm is not as mathematically rigorous as the Markov Chain Monte Carlo based algorithms most often used to determine exoplanetary system parameters, we show that it is straightforward and returns reliable results. Finally, we show that analyses performed with our model and optimization routine compare favorably with exoplanet characterizations published by groups such as the

  1. 什么是CM ROM?

    Institute of Scientific and Technical Information of China (English)

    方祺骏

    2011-01-01

    我的手机是MOTO的ME525,最近我在论坛上看到有一个叫CM7的2.3版ROM,请问这个ROM是怎么回事,安全稳定吗? CM是CyanogenMod的缩写庀是一个免费的、团队协作发布的Android第三方编译ROM。CM5可以理解成2.1版RoM,CM6就是2.2版ROM,而CM7代表2.3版RoM。

  2. CM()CN D-computable state

    Institute of Scientific and Technical Information of China (English)

    LIU DongDong; DI YaoMin

    2008-01-01

    The notions of D-computable state and D-concurrence are generalized to the CM()CN system. A class of D-computable state on CM()CN is given and the calculating method of the lower bound of D-concurrence is provided. The obvious expression of the lower bound of D-concurrence for the state mixed by two D-pure states is derived.

  3. Pencils on real curves

    CERN Document Server

    Coppens, Marc

    2011-01-01

    We consider coverings of real algebraic curves to real rational algebraic curves. We show the existence of such coverings having prescribed topological degree on the real locus. From those existence results we prove some results on Brill-Noether Theory for pencils on real curves. For coverings having topological degree 0 we introduce the covering number k and we prove the existence of coverings of degree 4 with prescribed covering number.

  4. Conducting Retrospective Ontological Clinical Trials in ICD-9-CM in the Age of ICD-10-CM

    Science.gov (United States)

    Venepalli, Neeta K; Shergill, Ardaman; Dorestani, Parvaneh; Boyd, Andrew D

    2014-01-01

    OBJECTIVE To quantify the impact of International Classification of Disease 10th Revision Clinical Modification (ICD-10-CM) transition in cancer clinical trials by comparing coding accuracy and data discontinuity in backward ICD-10-CM to ICD-9-CM mapping via two tools, and to develop a standard ICD-9-CM and ICD-10-CM bridging methodology for retrospective analyses. BACKGROUND While the transition to ICD-10-CM has been delayed until October 2015, its impact on cancer-related studies utilizing ICD-9-CM diagnoses has been inadequately explored. MATERIALS AND METHODS Three high impact journals with broad national and international readerships were reviewed for cancer-related studies utilizing ICD-9-CM diagnoses codes in study design, methods, or results. Forward ICD-9-CM to ICD-10-CM mapping was performing using a translational methodology with the Motif web portal ICD-9-CM conversion tool. Backward mapping from ICD-10-CM to ICD-9-CM was performed using both Centers for Medicare and Medicaid Services (CMS) general equivalence mappings (GEMs) files and the Motif web portal tool. Generated ICD-9-CM codes were compared with the original ICD-9-CM codes to assess data accuracy and discontinuity. RESULTS While both methods yielded additional ICD-9-CM codes, the CMS GEMs method provided incomplete coverage with 16 of the original ICD-9-CM codes missing, whereas the Motif web portal method provided complete coverage. Of these 16 codes, 12 ICD-9-CM codes were present in 2010 Illinois Medicaid data, and accounted for 0.52% of patient encounters and 0.35% of total Medicaid reimbursements. Extraneous ICD-9-CM codes from both methods (Centers for Medicare and Medicaid Services general equivalent mapping [CMS GEMs, n = 161; Motif web portal, n = 246]) in excess of original ICD-9-CM codes accounted for 2.1% and 2.3% of total patient encounters and 3.4% and 4.1% of total Medicaid reimbursements from the 2010 Illinois Medicare database. DISCUSSION Longitudinal data analyses post-ICD-10

  5. JUMPING THE CURVE

    Directory of Open Access Journals (Sweden)

    René Pellissier

    2012-01-01

    Full Text Available This paper explores the notion ofjump ing the curve,following from Handy 's S-curve onto a new curve with new rules policies and procedures. . It claims that the curve does not generally lie in wait but has to be invented by leadership. The focus of this paper is the identification (mathematically and inferentially ofthat point in time, known as the cusp in catastrophe theory, when it is time to change - pro-actively, pre-actively or reactively. These three scenarios are addressed separately and discussed in terms ofthe relevance ofeach.

  6. Lensing Measurements of the Ellipticity of LRG Dark Matter Halos

    CERN Document Server

    Clampitt, Joseph

    2015-01-01

    Lensing measurements of the shapes of dark matter halos can provide tests of gravity theories and possible dark matter interactions. We measure the quadrupole weak lensing signal from the elliptical halos of 70,000 SDSS Luminous Red Galaxies. We use a new estimator that nulls the spherical halo lensing signal, isolating the shear due to anisotropy in the dark matter distribution. One of the two Cartesian components of our estimator is insensitive to the primary systematic, a spurious alignment of lens and source ellipticities, allowing us to make robust measurements of halo ellipticity. Our best-fit value for the ellipticity of the surface mass density is 0.24, which translates to an axis ratio of 0.78. We rule out the hypothesis of no ellipticity at the 4-sigma confidence level, and ellipticity 0.89) at the 2-sigma level. We discuss how our measurements of halo ellipticity are revised to higher values using estimates of the misalignment of mass and light from simulations. Finally, we apply the same techniqu...

  7. Effective Elliptic Models for Efficient Wavefield Extrapolation in Anisotropic Media

    KAUST Repository

    Waheed, Umair bin

    2014-05-01

    Wavefield extrapolation operator for elliptically anisotropic media offers significant cost reduction compared to that of transversely isotropic media (TI), especially when the medium exhibits tilt in the symmetry axis (TTI). However, elliptical anisotropy does not provide accurate focusing for TI media. Therefore, we develop effective elliptically anisotropic models that correctly capture the kinematic behavior of the TTI wavefield. Specifically, we use an iterative elliptically anisotropic eikonal solver that provides the accurate traveltimes for a TI model. The resultant coefficients of the elliptical eikonal provide the effective models. These effective models allow us to use the cheaper wavefield extrapolation operator for elliptic media to obtain approximate wavefield solutions for TTI media. Despite the fact that the effective elliptic models are obtained by kinematic matching using high-frequency asymptotic, the resulting wavefield contains most of the critical wavefield components, including the frequency dependency and caustics, if present, with reasonable accuracy. The methodology developed here offers a much better cost versus accuracy tradeoff for wavefield computations in TTI media, considering the cost prohibitive nature of the problem. We demonstrate the applicability of the proposed approach on the BP TTI model.

  8. Detections of 2 cm formaldehyde emissions towards Galactic star-forming regions with 6 cm counterpart

    Science.gov (United States)

    Chen, Xi; Shen, Zhi-Qiang; Li, Xiao-Qiong; Yang, Kai; Li, Juan; Wang, Jun-Zhi; Wu, Ya-Jun; Zhao, Rong-Bin; Wang, Jin-Qing; Dong, Jian; Jiang, Dong-Rong; Li, Bin

    2017-01-01

    We report the detections of H2CO emission at the 2 cm transition towards Galactic star-forming regions with known 6 cm counterpart using the Shanghai Tianma Radio Telescope (TMRT). One significant detection (in NGC7538) and two possible detections (in G23.01-0.41 and G29.96-0.02) were made. Comparing with previous observations, we found that there is a time lag of appearance of 2 cm and 6 cm emissions detected in NGC7538, contradicting with the prediction of radiative pumping via radio continuum radiation. Combinations of the variability of 6 cm masers in NGC7538 suggest that collisional pumping via high-velocity shocks could better explain the 6 cm H2CO maser emission. Under this scheme, excitation of the 2 cm maser may require a higher collision energy compared to the 6 cm transition.

  9. Dusty Feedback from Massive Black Holes in Two Elliptical Galaxies

    Science.gov (United States)

    Temi, P.; Brighenti, F.; Mathews, W. G.; Amblard, A.; Riguccini, L.

    2013-01-01

    Far-infrared dust emission from elliptical galaxies informs us about galaxy mergers, feedback energy outbursts from supermassive black holes and the age of galactic stars. We report on the role of AGN feedback observationally by looking for its signatures in elliptical galaxies at recent epochs in the nearby universe. We present Herschel observations of two elliptical galaxies with strong and spatially extended FIR emission from colder grains 5-10 kpc distant from the galaxy cores. Extended excess cold dust emission is interpreted as evidence of recent feedback-generated AGN energy outbursts in these galaxies, visible only in the FIR, from buoyant gaseous outflows from the galaxy cores.

  10. Connecting Jacobi elliptic functions with different modulus parameters

    Indian Academy of Sciences (India)

    Avinash Khare; Uday Sukhatme

    2004-11-01

    The simplest formulas connecting Jacobi elliptic functions with different modulus parameters were first obtained over two hundred years ago by John Landen. His approach was to change integration variables in elliptic integrals. We show that Landen’s formulas and their subsequent generalizations can also be obtained from a different approach, using which we also obtain several new Landen transformations. Our new method is based on recently obtained periodic solutions of physically interesting non-linear differential equations and remarkable new cyclic identities involving Jacobi elliptic functions.

  11. New Elliptic Solutions of the Yang-Baxter Equation

    Science.gov (United States)

    Chicherin, D.; Derkachov, S. E.; Spiridonov, V. P.

    2016-07-01

    We consider finite-dimensional reductions of an integral operator with the elliptic hypergeometric kernel describing the most general known solution of the Yang-Baxter equation with a rank 1 symmetry algebra. The reduced R-operators reproduce at their bottom the standard Baxter's R-matrix for the 8-vertex model and Sklyanin's L-operator. The general formula has a remarkably compact form and yields new elliptic solutions of the Yang-Baxter equation based on the finite-dimensional representations of the elliptic modular double. The same result is also derived using the fusion formalism.

  12. Jacobi-Bessel analysis of reflector antennas with elliptical apertures

    Science.gov (United States)

    Rahmat-Samii, Yahya

    1987-01-01

    Although many reflector antennas possess circular projected apertures, there are recent satellite and ground antenna applications for which it is desirable to employ reflectors with elliptical apertures. Here a modification of the Jacobi-Bessel expansion is presented for the diffraction analysis of reflectors with elliptical apertures. A comparative study is also performed between this modified Jacobi-Bessel algorithm and the one which uses the Jacobi-Bessel expansion over a circumscribing circular region. Numerical results are presented for offset reflectors with elliptical and circular apertures and the improved convergence properties of the modified algorithm are highlighted.

  13. A Simple Birefringent Terahertz Waveguide Based on Polymer Elliptical Tube

    Institute of Scientific and Technical Information of China (English)

    WANG Jing-Li; YAO Jian-Quan; CHEN He-Ming; LI Zhong-Yang

    2011-01-01

    We propose a simple birefringent terahertz (THz) waveguide which is a polymer elliptical tube with a cross section of elliptical ring structure. It can be achieved by stretching a normal circular-tube in one direction. Simulations based on the full-vector finite element method (FEM) show that this kind of waveguides exhibits high birefringence on a level of 10-2 over a wide THz frequency range. Moreover, as a majority of modal power is trapped in the air core inside the polymer elliptical tube, the THz waveguide guiding loss caused by material absorption can be reduced effectively.

  14. Chatter Suppression with Ultrasonic Elliptical Vibration Based on Energy Principle

    Institute of Scientific and Technical Information of China (English)

    MA Chun-xiang; E Shamoto; T Moriwaki

    2005-01-01

    A new method is proposed to suppress chatter, in which the ultrasonic elliptical vibration is added on the cutting tool edge. It results in the fact that the rake face of tool is separated from the chip and the direction of the frictional force between the rake face and the chip is reversed in each cycle of elliptical vibration cutting. The experimental investigations show that the chatter can be suppressed effectively by adding ultrasonic elliptical vibration on the cutting tool edge. In order to make clear the reason of chatter suppression, the mechanism of chatter suppression is analyzed theoretically from the viewpoint of energy.

  15. Adaptive control for autonomous rendezvous of spacecraft on elliptical orbit

    Institute of Scientific and Technical Information of China (English)

    Shan Lu; Shijie Xu

    2009-01-01

    A strategy for spacecraft autonomous rendezvous on an elliptical orbit in situation of no orbit information is developed. Lawden equation is used to describe relative motion of two spacecraft. Then an adaptive gain factor is introduced, and an adaptive control law for autonomous rendezvous on the elliptical orbit is designed using Lyapunov approach. The relative motion is proved to be ultimately bounded under this control law, and the final relative position error can achieve the expected magnitude. Simulation results indicate that the adaptive control law can realize autonomous rendezvous on the elliptical orbit with relative state information only.

  16. Perturbation of essential spectra of exterior elliptic problems

    DEFF Research Database (Denmark)

    Grubb, Gerd

    2011-01-01

    For a second-order symmetric strongly elliptic differential operator on an exterior domain in ℝ n , it is known from the works of Birman and Solomiak that a change in the boundary condition from the Dirichlet condition to an elliptic Neumann or Robin condition leaves the essential spectrum...... an extension of the spectral asymptotics formula for the difference between inverses of elliptic problems. The proofs rely on Kreĭn-type formulae for differences between inverses, and cutoff techniques, combined with results on singular Green operators and their spectral asymptotics....

  17. Multilevel quadrature of elliptic PDEs with log-normal diffusion

    KAUST Repository

    Harbrecht, Helmut

    2015-01-07

    We apply multilevel quadrature methods for the moment computation of the solution of elliptic PDEs with lognormally distributed diffusion coefficients. The computation of the moments is a difficult task since they appear as high dimensional Bochner integrals over an unbounded domain. Each function evaluation corresponds to a deterministic elliptic boundary value problem which can be solved by finite elements on an appropriate level of refinement. The complexity is thus given by the number of quadrature points times the complexity for a single elliptic PDE solve. The multilevel idea is to reduce this complexity by combining quadrature methods with different accuracies with several spatial discretization levels in a sparse grid like fashion.

  18. The rotation curve of spiral galaxies and its cosmological implications

    CERN Document Server

    Florido, E

    2000-01-01

    We review the topic of rotation curves of spiral galaxies emphasizing the standard interpretation as evidence for the existence of dark matter halos. Galaxies other than spirals and late-type dwarfs may also possess great amounts of dark matter, and therefore ellipticals, dwarf spirals, lenticulars and polar ring galaxies are also considered. Furthermore, other methods for determining galactic dark matter, such as those provided by binaries, satellites or globular clusters, have to be included. Cold dark matter hierarchical models constitute the standard way to explain rotation curves, and thus the problem becomes just one aspect of a more general theory explaining structure and galaxy formation. Alternative theories also are included. In the magnetic model, rotation curves could also be a particular aspect of the whole history of cosmic magnetism during different epochs of the Universe. Modifications of Newtonian Dynamics provide another interesting possibility which is discussed here.

  19. Simulating Supernova Light Curves

    Energy Technology Data Exchange (ETDEWEB)

    Even, Wesley Paul [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Dolence, Joshua C. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2016-05-05

    This report discusses supernova light simulations. A brief review of supernovae, basics of supernova light curves, simulation tools used at LANL, and supernova results are included. Further, it happens that many of the same methods used to generate simulated supernova light curves can also be used to model the emission from fireballs generated by explosions in the earth’s atmosphere.

  20. Tempo curves considered harmful

    NARCIS (Netherlands)

    Desain, P.; Honing, H.

    1993-01-01

    In the literature of musicology, computer music research and the psychology of music, timing or tempo measurements are mostly presented in the form of continuous curves. The notion of these tempo curves is dangerous, despite its widespread use, because it lulls its users into the false impression th

  1. Pairings on hyperelliptic curves

    CERN Document Server

    Balakrishnan, Jennifer; Chisholm, Sarah; Eisentraeger, Kirsten; Stange, Katherine; Teske, Edlyn

    2009-01-01

    We assemble and reorganize the recent work in the area of hyperelliptic pairings: We survey the research on constructing hyperelliptic curves suitable for pairing-based cryptography. We also showcase the hyperelliptic pairings proposed to date, and develop a unifying framework. We discuss the techniques used to optimize the pairing computation on hyperelliptic curves, and present many directions for further research.

  2. Retrospectives: Engel Curves

    National Research Council Canada - National Science Library

    Andreas Chai; Alessio Moneta

    2010-01-01

    ..., Professor of Economics, University of Illinois, Chicago, at jpersky@uic.edu jpersky@uic.edu.. Introduction Introduction Engel curves describe how household expenditure on particular goods or Engel curves describe how household expenditure on particular goods or services depends on household income. The name comes from the German st...

  3. Tornado-Shaped Curves

    Science.gov (United States)

    Martínez, Sol Sáez; de la Rosa, Félix Martínez; Rojas, Sergio

    2017-01-01

    In Advanced Calculus, our students wonder if it is possible to graphically represent a tornado by means of a three-dimensional curve. In this paper, we show it is possible by providing the parametric equations of such tornado-shaped curves.

  4. Organizing the Parameter Space of the Global 21-cm Signal

    CERN Document Server

    Cohen, Aviad; Barkana, Rennan; Lotem, Matan

    2016-01-01

    The early star-forming Universe is still poorly constrained, with the properties of high-redshift stars, the first heating sources, and reionization highly uncertain. This leaves observers planning 21-cm experiments with little theoretical guidance. In this work we explore the possible range of high-redshift parameters including the star formation efficiency and the minimal mass of star-forming halos; the efficiency, spectral energy distribution, and redshift evolution of the first X-ray sources; and the history of reionization. These parameters are only weakly constrained by available observations, mainly the optical depth to the cosmic microwave background. We use realistic semi-numerical simulations to produce the global 21-cm signal over the redshift range $z = 6-40$ for each of 181 different combinations of the astrophysical parameters spanning the allowed range. We show that the expected signal fills a large parameter space, but with a fixed general shape for the global 21-cm curve. Even with our wide s...

  5. The curve shortening problem

    CERN Document Server

    Chou, Kai-Seng

    2001-01-01

    Although research in curve shortening flow has been very active for nearly 20 years, the results of those efforts have remained scattered throughout the literature. For the first time, The Curve Shortening Problem collects and illuminates those results in a comprehensive, rigorous, and self-contained account of the fundamental results.The authors present a complete treatment of the Gage-Hamilton theorem, a clear, detailed exposition of Grayson''s convexity theorem, a systematic discussion of invariant solutions, applications to the existence of simple closed geodesics on a surface, and a new, almost convexity theorem for the generalized curve shortening problem.Many questions regarding curve shortening remain outstanding. With its careful exposition and complete guide to the literature, The Curve Shortening Problem provides not only an outstanding starting point for graduate students and new investigations, but a superb reference that presents intriguing new results for those already active in the field.

  6. Lensing Reconstruction using redshifted 21cm Fluctuations

    CERN Document Server

    Zahn, O; Zahn, Oliver; Zaldarriaga, Matias

    2005-01-01

    We investigate the potential of second generation measurements of redshifted 21 cm radiation from the epoch of reionization (EOR) to reconstruct the matter density fluctuations along the line of sight. To do so we generalize the quadratic methods developed for the Cosmic Microwave Background (CMB) to 21cm fluctuations. The three dimensional signal can be analyzed into a finite number of line of sight Fourier modes that contribute to the lensing reconstruction. In comparison with reconstruction using the CMB, 21cm fluctuations have a disadvantage of relative featurelessness, which can be compensated for by the fact that there are multiple uncorrelated backgrounds. The multiple redshift information allows to reconstruct relatively small scales even if one is limited by angular resolution. We estimate that a square kilometer of collecting area is needed with a maximal baseline of 3 km to achieve lensing reconstruction noise levels an order of magnitude below CMB quadratic estimator constraints at $l=1000$, and c...

  7. TETRAHEDRAL Cm INTERPOLATION BY RATIONAL FUNCTIONS

    Institute of Scientific and Technical Information of China (English)

    Guo-liang Xu; Chuan I Chu; Wei-min Xue

    2001-01-01

    A general local Cm(m ≥ 0) tetrahedral interpolation scheme bypolynomials of degree 4m + l plus low order rational functions from the given data is proposed. The scheme can have either 4m + l order algebraic precision if C2m data at vertices and Cm data on faces are given or k + E[k/3] + 1 order algebraic precision if Ck (k ≤ 2m) data are given at vertices. The resulted interpolant and its partial derivatives of up to order m are polynomials on the boundaries of the tetrahedra.

  8. Electron energy spectrum in core-shell elliptic quantum wire

    Directory of Open Access Journals (Sweden)

    V.Holovatsky

    2007-01-01

    Full Text Available The electron energy spectrum in core-shell elliptic quantum wire and elliptic semiconductor nanotubes are investigated within the effective mass approximation. The solution of Schrodinger equation based on the Mathieu functions is obtained in elliptic coordinates. The dependencies of the electron size quantization spectrum on the size and shape of the core-shell nanowire and nanotube are calculated. It is shown that the ellipticity of a quantum wire leads to break of degeneration of quasiparticle energy spectrum. The dependences of the energy of odd and even electron states on the ratio between semiaxes are of a nonmonotonous character. The anticrosing effects are observed at the dependencies of electron energy spectrum on the transversal size of the core-shell nanowire.

  9. Concentrating solutions of some singularly perturbed elliptic equations

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    We study singularly perturbed elliptic equations arising from models in physics or biology, and investigate the asymptotic behavior of some special solutions. We also discuss some connections with problems arising in differential geometry.

  10. Maximum Principle for Nonlinear Cooperative Elliptic Systems on IR N

    Institute of Scientific and Technical Information of China (English)

    LEADI Liamidi; MARCOS Aboubacar

    2011-01-01

    We investigate in this work necessary and sufficient conditions for having a Maximum Principle for a cooperative elliptic system on the whole (IR)N.Moreover,we prove the existence of solutions by an approximation method for the considered system.

  11. Topology of the elliptical billiard with the Hooke's potential

    OpenAIRE

    Radnović Milena

    2015-01-01

    Using Fomenko graphs, we present a topological description of the elliptical billiard with Hooke's potential. [Projekat Ministarstva nauke Republike Srbije, br. 174020: Geometry and Topology of Manifolds and Integrable Dynamical Systems

  12. Topology of the elliptical billiard with the Hooke's potential

    Directory of Open Access Journals (Sweden)

    Radnović Milena

    2015-01-01

    Full Text Available Using Fomenko graphs, we present a topological description of the elliptical billiard with Hooke's potential. [Projekat Ministarstva nauke Republike Srbije, br. 174020: Geometry and Topology of Manifolds and Integrable Dynamical Systems

  13. Semilinear elliptic problems on unbounded subsets of the Heisenberg group

    Directory of Open Access Journals (Sweden)

    K. Tintarev

    2001-03-01

    Full Text Available In this paper we discuss the applications of an abstract version of concentration compactness to minimax problems. In particular, we prove the existence of solutions to semilinear elliptic problems on unbounded subsets of the Heisenberg group.

  14. Some function spaces and elliptic partial differential equations

    Directory of Open Access Journals (Sweden)

    Pietro Zamboni

    1987-11-01

    Full Text Available In this paper we compare some function spaces which are relevant to an integral inequality.An unique continuation result for nonnegative solution of elliptic P.D.E.'s is also proved.

  15. On a quasilinear elliptic eigenvalue problem with constraint

    Institute of Scientific and Technical Information of China (English)

    2004-01-01

    Via construction of pseudo gradient vector field and descending flow argument, we prove the existence of one positive, one negative and one sign-changing solutions for a quasilinear elliptic eigenvalue problem with constraint.

  16. ON AN ELLIPTIC PROBLEM INVOLVING CRITICAL AND SUBLINEAR GROWTH

    Institute of Scientific and Technical Information of China (English)

    YANG Haitao

    2002-01-01

    In this paper, the author considers an elliptic problem with critical and sublinear growth. Some results about the multiplicity and uniqueness of the positive solutions are given by making use of variational method and bifurcation theory.

  17. Existence of solutions for elliptic systems with critical Sobolev exponent

    Directory of Open Access Journals (Sweden)

    Pablo Amster

    2002-06-01

    Full Text Available We establish conditions for existence and for nonexistence of nontrivial solutions to an elliptic system of partial differential equations. This system is of gradient type and has a nonlinearity with critical growth.

  18. Stable equilibria of elliptic roly-poly toys

    Science.gov (United States)

    Hong, Seok-In

    2016-11-01

    As an instructive (gravitational potential) energy approach, we show that the elliptic roly-poly has a richer and more useful profile (including the tilted configuration) of stable equilibria than conventional spherical or cylindrical roly-polys.

  19. On mixed finite element techniques for elliptic problems

    Directory of Open Access Journals (Sweden)

    M. Aslam Noor

    1983-01-01

    mildly nonlinear elliptic problems by means of finite element methods of mixed type. The technique is based on an extended variational principle, in which the constraint of interelement continuity has been removed at the expense of introducing a Lagrange multiplier.

  20. Electromagnetic fields and Green functions in elliptical vacuum chambers

    CERN Document Server

    Persichelli, Serena; Migliorati, Mauro; Palumbo, Luigi; Vaccaro, Vittorio; CERN. Geneva. ATS Department

    2017-01-01

    In this paper, we discuss the electromagnetic interaction between a point charge travelling inside a waveguide of elliptical cross section, and the waveguide itself. By using a convenient expansion of the Mathieu functions, useful in particular for treating a variety of problems in applied mathematics and physics with elliptic geometry, we first obtain the longitudinal electromagnetic field of a point charge (Green function) in free space in terms of elliptical coordinates. This expression allows, then, to calculate the scattered field due to the boundary conditions in our geometry. By summing the contribution of the direct or primary field and the indirect field scattered by the boundary, after a careful choice of some expansion expressions, we derive a novel formula of the longitudinal electric field, in any transverse position of the elliptical cross section, generated by the charge moving along the longitudinal axis of the waveguide. The obtained expression is represented in a closed form, it can be diffe...

  1. Mergers of elliptical galaxies and the fundamental plane

    NARCIS (Netherlands)

    Gonzalez-Garcia, AC; van Albada, TS; AvilaReese,; Firmani, C; Frenk, CS; Allen, YC

    2003-01-01

    N-body simulations have been carried out in order to explore the final state of elliptical galaxies after encounters and more expecifically whether the Fundamental Plane (FP hereafter) relation is affected by merging.

  2. epsnoise: Pixel noise in ellipticity and shear measurements

    Science.gov (United States)

    Melchior, Peter; Viola, Massimo

    2012-04-01

    epsnoise simulates pixel noise in weak-lensing ellipticity and shear measurements. This open-source python code can efficiently create an intrinsic ellipticity distribution, shear it, and add noise, thereby mimicking a "perfect" measurement that is not affected by shape-measurement biases. For theoretical studies, we provide the Marsaglia distribution, which describes the ratio of normal variables in the general case of non-zero mean and correlation. We also added a convenience method that evaluates the Marsaglia distribution for the ratio of moments of a Gaussian-shaped brightness distribution, which gives a very good approximation of the measured ellipticity distribution also for galaxies with different radial profiles. We provide four shear estimators, two based on the ɛ ellipticity measure, two on χ. While three of them are essentially plain averages, we introduce a new estimator which requires a functional minimization.

  3. Elliptical hole in a bulk superconductor under electromagnetic forces

    Energy Technology Data Exchange (ETDEWEB)

    Yong Huadong; Zhou Youhe [Key Laboratory of Mechanics on Western Disaster and Environment, Ministry of Education, Lanzhou 730000 (China); Department of Mechanics, Lanzhou University, Lanzhou 730000 (China)

    2009-02-15

    A simple model is presented for the distribution of flux-pinning-induced stress in a superconductor around an elliptical hole and the singular stress field near crack tips. The magnetic behavior is described by the critical state, the original Bean model. It is assumed that the perturbation brought upon by the elliptical hole on the critical current density is not significant. Explicit expressions for the stress field in the vicinity of an elliptical hole are derived based on the complex variable method. Furthermore, the stress intensity factor at the tip of a slender crack is determined. An exact solution is found during the decreasing field and field-cooling process. Dependence of the stress field on the parameters including the applied field, shape of the elliptical hole or superconductor slab is investigated. The results show that the applied field and geometry parameter have obvious effects on the distribution of the stress.

  4. Elliptical hole in a bulk superconductor under electromagnetic forces

    Science.gov (United States)

    Yong, Hua-Dong; Zhou, You-He

    2009-02-01

    A simple model is presented for the distribution of flux-pinning-induced stress in a superconductor around an elliptical hole and the singular stress field near crack tips. The magnetic behavior is described by the critical state, the original Bean model. It is assumed that the perturbation brought upon by the elliptical hole on the critical current density is not significant. Explicit expressions for the stress field in the vicinity of an elliptical hole are derived based on the complex variable method. Furthermore, the stress intensity factor at the tip of a slender crack is determined. An exact solution is found during the decreasing field and field-cooling process. Dependence of the stress field on the parameters including the applied field, shape of the elliptical hole or superconductor slab is investigated. The results show that the applied field and geometry parameter have obvious effects on the distribution of the stress.

  5. Quasi-Hopf twistors for elliptic quantum groups

    CERN Document Server

    Jimbo, M; Odake, S; Shiraishi, J

    1997-01-01

    The Yang-Baxter equation admits two classes of elliptic solutions, the vertex type and the face type. On the basis of these solutions, two types of elliptic quantum groups have been introduced (Foda et al., Felder). Fronsdal made a penetrating observation that both of them are quasi-Hopf algebras, obtained by twisting the standard quantum affine algebra U_q(g). In this paper we present an explicit formula for the twistors in the form of an infinite product of the universal R matrix of U_q(g). We also prove the shifted cocycle condition for the twistors, thereby completing Fronsdal's findings. This construction entails that, for generic values of the deformation parameters, representation theory for U_q(g) carries over to the elliptic algebras, including such objects as evaluation modules, highest weight modules and vertex operators. In particular, we confirm the conjectures of Foda et al. concerning the elliptic algebra A_{q,p}(^sl_2).

  6. Vertical elliptic operator for efficient wave propagation in TTI media

    KAUST Repository

    Waheed, Umair bin

    2015-08-19

    Elliptic wave extrapolation operators require significantly less computational cost than the ones for transversely isotropic (TI) media. However, it does not provide accurate wavefield representation or imaging for the prevalent TI media. We propose a new vertical elliptically anisotropic (VEA) wave equation by decomposing the acoustic TI pseudo-differential wave equation. The decomposition results in a vertical elliptic differential equation and a scalar operator. The new VEA-like wave equation shares the same dispersion relation as that of the original acoustic TI wave equation. Therefore, the kinematic contents are correctly matched to the original equation. Moreover, the proposed decomposition yields better amplitude properties than the isotropic decomposition without increasing the computational load. Therefore, it exhibits better cost versus accuracy tradeoff compared to the isotropic or the tilted elliptic decompositions. We demonstrate with numerical examples that the proposed methodology is numerically stable for complex models and is free from shear-wave artifacts.

  7. Effect of flow fluctuations and nonflow on elliptic flow methods

    Energy Technology Data Exchange (ETDEWEB)

    Ollitrault, Jean-Yves; Poskanzer, Arthur M.; Voloshin, Sergei A.

    2009-04-16

    We discuss how the different estimates of elliptic flow are influenced by flow fluctuations and nonflow effects. It is explained why the event-plane method yields estimates between the two-particle correlation methods and the multiparticle correlation methods. It is argued that nonflow effects and fluctuations cannot be disentangled without other assumptions. However, we provide equations where, with reasonable assumptions about fluctuations and nonflow, all measured values of elliptic flow converge to a unique mean v_2,PP elliptic flow in the participant plane and, with a Gaussian assumption on eccentricity fluctuations, can be converted to the mean v_2,RP in the reaction plane. Thus, the 20percent spread in observed elliptic flow measurements from different analysis methods is no longer mysterious.

  8. Elliptic Solvers with Adaptive Mesh Refinement on Complex Geometries

    Energy Technology Data Exchange (ETDEWEB)

    Phillip, B.

    2000-07-24

    Adaptive Mesh Refinement (AMR) is a numerical technique for locally tailoring the resolution computational grids. Multilevel algorithms for solving elliptic problems on adaptive grids include the Fast Adaptive Composite grid method (FAC) and its parallel variants (AFAC and AFACx). Theory that confirms the independence of the convergence rates of FAC and AFAC on the number of refinement levels exists under certain ellipticity and approximation property conditions. Similar theory needs to be developed for AFACx. The effectiveness of multigrid-based elliptic solvers such as FAC, AFAC, and AFACx on adaptively refined overlapping grids is not clearly understood. Finally, a non-trivial eye model problem will be solved by combining the power of using overlapping grids for complex moving geometries, AMR, and multilevel elliptic solvers.

  9. Quasiconformal mappings and degenerate elliptic and parabolic equations

    Directory of Open Access Journals (Sweden)

    Filippo Chiarenza

    1987-11-01

    Full Text Available In this paper two Harnak inequalities are proved concerning a degenerate elliptic and a degenerate parabolic equation. In both cases the weight giving the degeneracy is a power of the jacobian of a quasiconformal mapping.

  10. Optimal Rendezvous and Docking Simulator for Elliptical Orbits Project

    Data.gov (United States)

    National Aeronautics and Space Administration — It is proposed to develop and implement a simulation of spacecraft rendezvous and docking guidance, navigation, and control in elliptical orbit. The foundation of...

  11. Learning Curve? Which One?

    Directory of Open Access Journals (Sweden)

    Paulo Prochno

    2004-07-01

    Full Text Available Learning curves have been studied for a long time. These studies provided strong support to the hypothesis that, as organizations produce more of a product, unit costs of production decrease at a decreasing rate (see Argote, 1999 for a comprehensive review of learning curve studies. But the organizational mechanisms that lead to these results are still underexplored. We know some drivers of learning curves (ADLER; CLARK, 1991; LAPRE et al., 2000, but we still lack a more detailed view of the organizational processes behind those curves. Through an ethnographic study, I bring a comprehensive account of the first year of operations of a new automotive plant, describing what was taking place on in the assembly area during the most relevant shifts of the learning curve. The emphasis is then on how learning occurs in that setting. My analysis suggests that the overall learning curve is in fact the result of an integration process that puts together several individual ongoing learning curves in different areas throughout the organization. In the end, I propose a model to understand the evolution of these learning processes and their supporting organizational mechanisms.

  12. Elliptic Genus of E-strings

    CERN Document Server

    Kim, Joonho; Lee, Kimyeong; Park, Jaemo; Vafa, Cumrun

    2014-01-01

    We study a family of 2d N=(0,4) gauge theories which describes at low energy the dynamics of E-strings, the M2-branes suspended between a pair of M5 and M9 branes. The gauge theory is engineered using a duality with type IIA theory, leading to the D2-branes suspended between an NS5-brane and 8 D8-branes on an O8-plane. We compute the elliptic genus of this family of theories, and find agreement with the known results for single and two E-strings. The partition function can in principle be computed for arbitrary number of E-strings, and we compute them explicitly for low numbers. We test our predictions against the partially known results from topological strings, as well as from the instanton calculus of 5d Sp(1) gauge theory. Given the relation to topological strings, our computation provides the all genus partition function of the refined topological strings on the canonical bundle over 1/2 K3.

  13. Nonlinear Elliptic Differential Equations with Multivalued Nonlinearities

    Indian Academy of Sciences (India)

    Antonella Fiacca; Nikolaos Matzakos; Nikolaos S Papageorgiou; Raffaella Servadei

    2001-11-01

    In this paper we study nonlinear elliptic boundary value problems with monotone and nonmonotone multivalued nonlinearities. First we consider the case of monotone nonlinearities. In the first result we assume that the multivalued nonlinearity is defined on all $\\mathbb{R}$. Assuming the existence of an upper and of a lower solution, we prove the existence of a solution between them. Also for a special version of the problem, we prove the existence of extremal solutions in the order interval formed by the upper and lower solutions. Then we drop the requirement that the monotone nonlinearity is defined on all of $\\mathbb{R}$. This case is important because it covers variational inequalities. Using the theory of operators of monotone type we show that the problem has a solution. Finally in the last part we consider an eigenvalue problem with a nonmonotone multivalued nonlinearity. Using the critical point theory for nonsmooth locally Lipschitz functionals we prove the existence of at least two nontrivial solutions (multiplicity theorem).

  14. Thermodynamics of Inozemtsev's Elliptic Spin Chain

    CERN Document Server

    Klabbers, Rob

    2016-01-01

    We study the thermodynamic behaviour of Inozemtsev's long-range elliptic spin chain using the Bethe ansatz equations describing the spectrum of the model in the infinite-length limit. We classify all solutions of these equations in that limit and argue which of these solutions determine the spectrum in the thermodynamic limit. Interestingly, some of the solutions are not selfconjugate, which puts the model in sharp contrast to one of the model's limiting cases, the Heisenberg xxx spin chain. Invoking the string hypothesis we derive the thermodynamic Bethe ansatz equations (TBA-equations) from which we determine the Helmholtz free energy in thermodynamic equilibrium and derive the associated Y-system. We corroborate our results by comparing numerical solutions of the TBA-equations to a direct computation of the free energy for the finite-length hamiltonian. In addition we confirm numerically the interesting conjecture put forward by Finkel and Gonz\\'alez-L\\'opez that the original and supersymmetric versions of...

  15. Maribo - a new CM fall from Denmark

    DEFF Research Database (Denmark)

    Haack, Henning; Grau, Thomas; Bischoff, Addi

    2012-01-01

    Maribo is a new Danish CM chondrite, which fell on January 17, 2009, at 19:08:28 CET. The fall was observed by many eye witnesses and recorded by a surveillance camera, an all sky camera, a few seismic stations, and by meteor radar observatories in Germany. A single fragment of Maribo with a dry...

  16. Stress analysis of electrostrictive material with an elliptic defect

    Institute of Scientific and Technical Information of China (English)

    Jiang; Quan; (蒋泉); Kuang; Zhenbang; (匡震邦)

    2003-01-01

    It is shown that the constitutive equation and electric body force used to discuss the stress analysis of electrostrictive material in some previous literature are not appropriate. This paper presents the corrected stress solution for the infinite plane with an insulated elliptic hole under an applied electrical field. The numerical result obtained for the PMN material constants show that the stress near the end of the narrow elliptic hole is the tensile stress.

  17. Elliptic partial differential equations existence and regularity of distributional solutions

    CERN Document Server

    Boccardo, Lucio

    2013-01-01

    Elliptic partial differential equations is one of the main and most active areas in mathematics. In our book we study linear and nonlinear elliptic problems in divergence form, with the aim of providing classical results, as well as more recent developments about distributional solutions. For this reason the book is addressed to master's students, PhD students and anyone who wants to begin research in this mathematical field.

  18. Center for Elliptic Quantum Group Eτ,η(sln)

    Institute of Scientific and Technical Information of China (English)

    ZHAO Shao-You; SHI Kang-Jie; YUE Rui-Hong

    2003-01-01

    We give the center of the elliptic quantum group in general cases. Based on the dynamical Yang-Baxter relation and the fusion method, we prove that the center commutes with all generators of the elliptic quantum group. Then for a kind of assumed form of these generators, we find that the coefficients of these generators form a new type of closed algebra. We also give the center for the algebra.

  19. Depth-resolved measurements with elliptically polarized reflectance spectroscopy.

    Science.gov (United States)

    Bailey, Maria J; Sokolov, Konstantin

    2016-07-01

    The ability of elliptical polarized reflectance spectroscopy (EPRS) to detect spectroscopic alterations in tissue mimicking phantoms and in biological tissue in situ is demonstrated. It is shown that there is a linear relationship between light penetration depth and ellipticity. This dependence is used to demonstrate the feasibility of a depth-resolved spectroscopic imaging using EPRS. The advantages and drawbacks of EPRS in evaluation of biological tissue are analyzed and discussed.

  20. The stability for the Cauchy problem for elliptic equations

    CERN Document Server

    Alessandrini, Giovanni; Rosset, Edi; Vessella, Sergio

    2009-01-01

    We discuss the ill-posed Cauchy problem for elliptic equations, which is pervasive in inverse boundary value problems modeled by elliptic equations. We provide essentially optimal stability results, in wide generality and under substantially minimal assumptions. As a general scheme in our arguments, we show that all such stability results can be derived by the use of a single building brick, the three-spheres inequality.

  1. Banana orbits in elliptic tokamaks with hole currents

    Science.gov (United States)

    Martin, P.; Castro, E.; Puerta, J.

    2015-03-01

    Ware Pinch is a consequence of breaking of up-down symmetry due to the inductive electric field. This symmetry breaking happens, though up-down symmetry for magnetic surface is assumed. In previous work Ware Pinch and banana orbits were studied for tokamak magnetic surface with ellipticity and triangularity, but up-down symmetry. Hole currents appear in large tokamaks and their influence in Ware Pinch and banana orbits are now considered here for tokamaks magnetic surfaces with ellipticity and triangularity.

  2. On elliptic cylindrical Kadomtsev-Petviashvili equation for surface waves

    CERN Document Server

    Khusnutdinova, K R; Matveev, V B; Smirnov, A O

    2012-01-01

    The `elliptic cylindrical Kadomtsev-Petviashvili equation' is derived for surface gravity waves with nearly-elliptic front, generalising the cylindrical KP equation for nearly-concentric waves. We discuss transformations between the derived equation and two existing versions of the KP equation, for nearly-plane and nearly-concentric waves. The transformations are used to construct important classes of exact solutions of the derived equation and corresponding approximate solutions for surface waves.

  3. Cotton-Type and Joint Invariants for Linear Elliptic Systems

    Directory of Open Access Journals (Sweden)

    A. Aslam

    2013-01-01

    that Cotton-type invariants derived from these two approaches are identical. Furthermore, Cotton-type and joint invariants for a general system of two linear elliptic equations are also obtained from the Laplace-type and joint invariants for a system of two linear hyperbolic equations equivalent to the system of linear elliptic equations by complex changes of the independent variables. Examples are presented to illustrate the results.

  4. Slip Flow in Elliptic Microducts with Constant Heat Flux

    Directory of Open Access Journals (Sweden)

    Marco Spiga

    2012-01-01

    Full Text Available This paper outlines a numerical model for determining the dynamic and thermal performances of a rarefied fluid flowing in a microduct with elliptical cross-section. A slip flow is considered, in laminar steady state condition, in fully developed forced convection, with Knudsen number in the range 0.001−0.1, in H1 boundary conditions. The velocity and temperature distributions are determined in the elliptic cross-section, for different values of both aspect ratio γ and Knudsen number, resorting to the Comsol Multiphysics software, to solve the momentum and energy equations. The friction factors (or Poiseuille numbers and the convective heat transfer coefficients (or Nusselt numbers are calculated and presented in graphs and tables. The numerical solution is validated resorting to data available in literature for continuum flow in elliptic cross-sections (Kn = 0 and for slip flow in circular ducts (γ=1. A further benchmark is carried out for the velocity profile for slip flow in ellipticalcross-sections, thanks to a recent analytical solution obtained using elliptic cylinder coordinates and the separation of variables method. The Poiseuille and Nusselt numbers for elliptic cross-sections are discussed. The results may be used to predict pressure drop and heat transfer performance in metallic microducts with elliptic cross-section, produced by microfabrication for microelectromechanical systems (MEMS.

  5. The redshift evolution of the stellar populations in elliptical galaxies

    CERN Document Server

    Bender, R; Bruzual, A G; Bender, Ralf; Ziegler, Bodo; Bruzual, Gustavo

    1996-01-01

    Velocity dispersions \\sigma and Mg absorption line-strengths Mg_b have been measured for a sample of 16 ellipticals in 3 clusters at a redshift of 0.37. Like local cluster ellipticals, these objects show a correlation between Mg_b and \\sigma. However, at any given \\sigma, the mean Mg_b of the ellipticals at z=0.37 is weaker than the mean Mg_b of their local relatives in the Coma and Virgo clusters. The Mg_b weakening is smallest for the most luminous ellipticals and larger for the fainter objects. This is unambiguous evidence for {\\it small but significant passive evolution} of the stellar populations of elliptical galaxies with redshift. It requires that the bulk of the stars in cluster ellipticals has formed at z>2. The most luminous objects may even have formed at z>4. The Mg_b-\\sigma test is a very reliable estimator for the evolution of old stellar populations because it is virtually independent from the stellar initial mass function (IMF) and from the metallicities of the galaxies. Furthermore, the infl...

  6. Aspects of quantum field theory in curved space-time

    Energy Technology Data Exchange (ETDEWEB)

    Fulling, S.A. (Texas A and M Univ., College Station, TX (USA). Dept. of Mathematics)

    1989-01-01

    The theory of quantum fields on curved spacetimes has attracted great attention since the discovery, by Stephen Hawking, of black-hole evaporation. It remains an important subject for the understanding of such contemporary topics as inflationary cosmology, quantum gravity and superstring theory. The topics covered include normal-mode expansions for a general elliptic operator, Fock space, the Casimir effect, the Klein 'paradox', particle definition and particle creation in expanding universes, asymptotic expansion of Green's functions and heat kernels, and renormalization of the stress tensor. (author).

  7. SRHA calibration curve

    Data.gov (United States)

    U.S. Environmental Protection Agency — an UV calibration curve for SRHA quantitation. This dataset is associated with the following publication: Chang, X., and D. Bouchard. Surfactant-Wrapped Multiwalled...

  8. ROBUST DECLINE CURVE ANALYSIS

    Directory of Open Access Journals (Sweden)

    Sutawanir Darwis

    2012-05-01

    Full Text Available Empirical decline curve analysis of oil production data gives reasonable answer in hyperbolic type curves situations; however the methodology has limitations in fitting real historical production data in present of unusual observations due to the effect of the treatment to the well in order to increase production capacity. The development ofrobust least squares offers new possibilities in better fitting production data using declinecurve analysis by down weighting the unusual observations. This paper proposes a robustleast squares fitting lmRobMM approach to estimate the decline rate of daily production data and compares the results with reservoir simulation results. For case study, we usethe oil production data at TBA Field West Java. The results demonstrated that theapproach is suitable for decline curve fitting and offers a new insight in decline curve analysis in the present of unusual observations.

  9. Similarity of skeletal objects in the range 10{sup -5} cm to 10{sup 23} cm

    Energy Technology Data Exchange (ETDEWEB)

    Kukushkin, A.B.; Rantsev-Kartinov, V.A

    2002-12-30

    The similarity of distinctive skeletal structures (namely, cartwheels and tubules) in the range 10{sup -5}-10{sup 23} cm is found. The former analysis of dust deposits in tokamak (10{sup -6}-10{sup -3} cm) and of electric discharges in tokamaks, Z-pinches, plasma focus and vacuum spark (10{sup -2}-10 cm) is extended here to hail particles (1-10 cm), tornado (10{sup 3}-10{sup 5} cm), and various objects in space (10{sup 11}-10{sup 23} cm). The similarity and the observed trend toward self-similarity within above skeletal structures suggest all of them, similarly to skeletons in the particles of dust and hail, to be basically a fractal condensed matter which, similarly to submicron dust skeletons, is assembled from nanotubular blocks.

  10. Interpreting Sky-Averaged 21-cm Measurements

    Science.gov (United States)

    Mirocha, Jordan

    2015-01-01

    Within the first ~billion years after the Big Bang, the intergalactic medium (IGM) underwent a remarkable transformation, from a uniform sea of cold neutral hydrogen gas to a fully ionized, metal-enriched plasma. Three milestones during this epoch of reionization -- the emergence of the first stars, black holes (BHs), and full-fledged galaxies -- are expected to manifest themselves as extrema in sky-averaged ("global") measurements of the redshifted 21-cm background. However, interpreting these measurements will be complicated by the presence of strong foregrounds and non-trivialities in the radiative transfer (RT) modeling required to make robust predictions.I have developed numerical models that efficiently solve the frequency-dependent radiative transfer equation, which has led to two advances in studies of the global 21-cm signal. First, frequency-dependent solutions facilitate studies of how the global 21-cm signal may be used to constrain the detailed spectral properties of the first stars, BHs, and galaxies, rather than just the timing of their formation. And second, the speed of these calculations allows one to search vast expanses of a currently unconstrained parameter space, while simultaneously characterizing the degeneracies between parameters of interest. I find principally that (1) physical properties of the IGM, such as its temperature and ionization state, can be constrained robustly from observations of the global 21-cm signal without invoking models for the astrophysical sources themselves, (2) translating IGM properties to galaxy properties is challenging, in large part due to frequency-dependent effects. For instance, evolution in the characteristic spectrum of accreting BHs can modify the 21-cm absorption signal at levels accessible to first generation instruments, but could easily be confused with evolution in the X-ray luminosity star-formation rate relation. Finally, (3) the independent constraints most likely to aide in the interpretation

  11. Large Curved Surface Measurement

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The measurement principle of large curved surface through theodolite industry survey system is introduced. Two methods are suggested with respect to the distribution range of curved surface error. The experiments show that the measurement precision can be up to 0.15mm with relative precision of 3×10-5. Finally, something needed paying attention to and the application aspects on theodolite industry survey system are given.

  12. Counting curves on surfaces

    OpenAIRE

    2015-01-01

    In this paper we consider an elementary, and largely unexplored, combinatorial problem in low-dimensional topology. Consider a real 2-dimensional compact surface $S$, and fix a number of points $F$ on its boundary. We ask: how many configurations of disjoint arcs are there on $S$ whose boundary is $F$? We find that this enumerative problem, counting curves on surfaces, has a rich structure. For instance, we show that the curve counts obey an effective recursion, in the general framework of to...

  13. Synchrotron radiation from a curved plasma channel laser wakefield accelerator

    CERN Document Server

    Palastro, J P; Hafizi, B; Chen, Y -H; Johnson, L A; Penano, J R; Helle, M H; Mamonau, A A

    2016-01-01

    A laser pulse guided in a curved plasma channel can excite wakefields that steer electrons along an arched trajectory. As the electrons are accelerated along the curved channel, they emit synchrotron radiation. We present simple analytical models and simulations examining laser pulse guiding, wakefield generation, electron steering, and synchrotron emission in curved plasma channels. For experimentally realizable parameters, a ~2 GeV electron emits 0.1 photons per cm with an average photon energy of multiple keV.

  14. Elliptic Bessel processes and elliptic Dyson models realized as temporally inhomogeneous processes

    Science.gov (United States)

    Katori, Makoto

    2016-10-01

    The Bessel process with parameter D > 1 and the Dyson model of interacting Brownian motions with coupling constant β > 0 are extended to the processes in which the drift term and the interaction terms are given by the logarithmic derivatives of Jacobi's theta functions. They are called the elliptic Bessel process, eBES(D), and the elliptic Dyson model, eDYS(β), respectively. Both are realized on the circumference of a circle [0, 2πr) with radius r > 0 as temporally inhomogeneous processes defined in a finite time interval [0, t∗), t∗ < ∞. Transformations of them to Schrödinger-type equations with time-dependent potentials lead us to proving that eBES(D) and eDYS(β) can be constructed as the time-dependent Girsanov transformations of Brownian motions. In the special cases where D = 3 and β = 2, observables of the processes are defined and the processes are represented for them using the Brownian paths winding round a circle and pinned at time t∗. We show that eDYS(2) has the determinantal martingale representation for any observable. Then it is proved that eDYS(2) is determinantal for all observables for any finite initial configuration without multiple points. Determinantal processes are stochastic integrable systems in the sense that all spatio-temporal correlation functions are given by determinants controlled by a single continuous function called the spatio-temporal correlation kernel.

  15. Elliptic Bessel processes and elliptic Dyson models realized as temporally inhomogeneous processes

    CERN Document Server

    Katori, Makoto

    2016-01-01

    The Bessel process with parameter $D>1$ and the Dyson model of interacting Brownian motions with coupling constant $\\beta >0$ are extended to the processes, in which the drift term and the interaction terms are given by the logarithmic derivatives of Jacobi's theta functions. They are called the elliptic Bessel process, eBES$^{(D)}$, and the elliptic Dyson model, eDYS$^{(\\beta)}$, respectively. Both are realized on the circumference of a circle $[0, 2 \\pi r)$ with radius $r >0$ as temporally inhomogeneous processes defined in a finite time interval $[0, t_*), t_* < \\infty$. Transformations of them to Schr\\"odinger-type equations with time-dependent potentials lead us to proving that eBES$^{(D)}$ and eDYS$^{(\\beta)}$ can be constructed as the time-dependent Girsanov transformations of Brownian motions. In the special cases where $D=3$ and $\\beta=2$, observables of the processes are defined and the processes are represented for them using the Brownian paths winding round a circle and pinned at time $t_*$. We...

  16. Redundant Array Configurations for 21 cm Cosmology

    CERN Document Server

    Dillon, Joshua S

    2016-01-01

    Realizing the potential of 21 cm tomography to statistically probe the intergalactic medium before and during the Epoch of Reionization requires large telescopes and precise control of systematics. Next-generation telescopes are now being designed and built to meet these challenges, drawing lessons from first-generation experiments that showed the benefits of densely packed, highly redundant arrays--in which the same mode on the sky is sampled by many antenna pairs--for achieving high sensitivity, precise calibration, and robust foreground mitigation. In this work, we focus on the Hydrogen Epoch of Reionization Array (HERA) as an interferometer with a dense, redundant core designed following these lessons to be optimized for 21 cm cosmology. We show how modestly supplementing or modifying a compact design like HERA's can still deliver high sensitivity while enhancing strategies for calibration and foreground mitigation. In particular, we compare the imaging capability of several array configurations, both ins...

  17. "Dehydrated" chondrules from the Murchison (CM) chondrite

    OpenAIRE

    Inoue, Mutsuo; Nakamura,Noboru

    1996-01-01

    Two "dehydrated" chondrules (MC-5 and MC-27) were obtained from close to the fusion crust of the Murchison (CM) meteorite. They have a porphyritic texture with angular or rounded (relict) olivines containing abundant voids, recrystallized olivines, and numerous interstitial Fe oxide grains embedded in groundmass glass. This peculiar texture is similar to that of the fusion crust from the Orgueil (CI) chondrite, indicating that the texture formed during the reheating at the atmospheric entry o...

  18. Constraining dark matter through 21-cm observations

    Science.gov (United States)

    Valdés, M.; Ferrara, A.; Mapelli, M.; Ripamonti, E.

    2007-05-01

    Beyond reionization epoch cosmic hydrogen is neutral and can be directly observed through its 21-cm line signal. If dark matter (DM) decays or annihilates, the corresponding energy input affects the hydrogen kinetic temperature and ionized fraction, and contributes to the Lyα background. The changes induced by these processes on the 21-cm signal can then be used to constrain the proposed DM candidates, among which we select the three most popular ones: (i) 25-keV decaying sterile neutrinos, (ii) 10-MeV decaying light dark matter (LDM) and (iii) 10-MeV annihilating LDM. Although we find that the DM effects are considerably smaller than found by previous studies (due to a more physical description of the energy transfer from DM to the gas), we conclude that combined observations of the 21-cm background and of its gradient should be able to put constrains at least on LDM candidates. In fact, LDM decays (annihilations) induce differential brightness temperature variations with respect to the non-decaying/annihilating DM case up to ΔδTb = 8 (22) mK at about 50 (15) MHz. In principle, this signal could be detected both by current single-dish radio telescopes and future facilities as Low Frequency Array; however, this assumes that ionospheric, interference and foreground issues can be properly taken care of.

  19. Comparison of elliptical training, stationary cycling, treadmill walking and overground walking. Electromyographic patterns.

    Science.gov (United States)

    Prosser, Laura A; Stanley, Christopher J; Norman, Tracy L; Park, Hyung S; Damiano, Diane L

    2011-02-01

    The most common functional motor goal of lower extremity rehabilitation is to improve walking ability. For reasons of feasibility, safety or intensity, devices are frequently used to facilitate or augment gait training. The objective of this study was to compare the muscle activity patterns of the rectus femoris and semitendinosus muscles during four conditions: overground walking, treadmill walking, stationary cycling, and elliptical training. Ten healthy adults (six male, four female; mean age 22.7±2.9 years, range 20-29) participated and surface electromyographic data were recorded. Linear envelope curves were generated and time normalized from 0 to 100% cycle. The mean plus three standard deviations from a static trial was used as the threshold for muscle activity. Repeated measures analysis of variance procedures were used to detect differences between conditions. Elliptical training demonstrated greater rectus femoris activity and greater rectus femoris/semitendinosus coactivation than all other conditions. Consistent with previous work, treadmill walking demonstrated greater rectus femoris activity than overground walking. Minimal differences in semitendinosus activation were observed between conditions, limited to lower peak activity during cycling compared to treadmill walking. These results provide normative values for rectus femoris and semitendinosus activation for different locomotor training methods and may assist in selecting the most appropriate training device for specific patients. Clinicians and researchers should also consider the kinematic and kinetic differences between tasks, which cannot necessarily be inferred from muscle activation patterns.

  20. Constraining the ellipticity of strongly magnetized neutron stars powering superluminous supernovae

    Science.gov (United States)

    Moriya, Takashi J.; Tauris, Thomas M.

    2016-07-01

    Superluminous supernovae (SLSNe) have been suggested to be powered by strongly magnetized, rapidly rotating neutron stars which are often called magnetars. In this process, rotational energy of the magnetar is radiated via magnetic dipole radiation and heats the supernova ejecta. However, if magnetars are highly distorted in their geometric shape, rotational energy is mainly lost as gravitational wave radiation and thus such magnetars cannot power SLSNe. By simply comparing electromagnetic and gravitational wave emission time-scales, we constrain upper limits to the ellipticity of magnetars by assuming that they power the observed SLSNe. We find that their ellipticity typically needs to be less than about a few 10-3. This indicates that the toroidal magnetic field strengths in these magnetars are typically less than a few 1016 G so that their distortions remain small. Because light-curve modelling of SLSNe shows that their dipole magnetic field strengths are of the order of 1014 G, the ratio of poloidal to toroidal magnetic field strengths is found to be larger than ˜0.01 in magnetars powering SLSNe.