An almost symmetric Strang splitting scheme for nonlinear evolution equations.
Einkemmer, Lukas; Ostermann, Alexander
2014-07-01
In this paper we consider splitting methods for the time integration of parabolic and certain classes of hyperbolic partial differential equations, where one partial flow cannot be computed exactly. Instead, we use a numerical approximation based on the linearization of the vector field. This is of interest in applications as it allows us to apply splitting methods to a wider class of problems from the sciences. However, in the situation described, the classic Strang splitting scheme, while still being a method of second order, is not longer symmetric. This, in turn, implies that the construction of higher order methods by composition is limited to order three only. To remedy this situation, based on previous work in the context of ordinary differential equations, we construct a class of Strang splitting schemes that are symmetric up to a desired order. We show rigorously that, under suitable assumptions on the nonlinearity, these methods are of second order and can then be used to construct higher order methods by composition. In addition, we illustrate the theoretical results by conducting numerical experiments for the Brusselator system and the KdV equation.
An Efficient Multi-keyword Symmetric Searchable Encryption Scheme for Secure Data Outsourcing
Vasudha Arora; S.S. Tyagi
2016-01-01
Symmetric searchable encryption (SSE) schemes allow a data owner to encrypt its data in such a way that it could be searched in encrypted form. When searching over encrypted data the retrieved data, search query, and search query outcome everything must be protected. A series of SSE schemes have been proposed in the past decade. In this paper, we are going to propose our an efficient multi-keyword symmetric searchable encryption scheme for secure data outsourcing and evaluate the performance ...
Dynamic Symmetric Key Mobile Commerce Scheme Based on Self-Verified Mechanism
Directory of Open Access Journals (Sweden)
Jiachen Yang
2014-01-01
Full Text Available In terms of the security and efficiency of mobile e-commerce, the authors summarized the advantages and disadvantages of several related schemes, especially the self-verified mobile payment scheme based on the elliptic curve cryptosystem (ECC and then proposed a new type of dynamic symmetric key mobile commerce scheme based on self-verified mechanism. The authors analyzed the basic algorithm based on self-verified mechanisms and detailed the complete transaction process of the proposed scheme. The authors analyzed the payment scheme based on the security and high efficiency index. The analysis shows that the proposed scheme not only meets the high efficiency of mobile electronic payment premise, but also takes the security into account. The user confirmation mechanism at the end of the proposed scheme further strengthens the security of the proposed scheme. In brief, the proposed scheme is more efficient and practical than most of the existing schemes.
Schur rings and non-symmetric association schemes on 64 vertices
DEFF Research Database (Denmark)
Jørgensen, Leif Kjær
2010-01-01
In this paper we enumerate essentially all non-symmetric association schemes with three classes, less than 96 vertices and with a regular group of automorphisms. The enumeration is based on a computer search in Schur rings. The most interesting cases have 64 vertices. In one primitive case...
Charge Orbits of Symmetric Special Geometries and Attractors
Bellucci, S; Günaydin, M; Marrani, A; Bellucci, Stefano; Ferrara, Sergio; Gunaydin, Murat; Marrani, Alessio
2006-01-01
We study the critical points of the black hole scalar potential $V_{BH}$ in N=2, d=4 supergravity coupled to $n_{V}$ vector multiplets, in an asymptotically flat extremal black hole background described by a 2(n_{V}+1)-dimensional dyonic charge vector and (complex) scalar fields which are coordinates of a special K\\"{a}hler manifold. For the case of homogeneous symmetric spaces, we find three general classes of regular attractor solutions with non-vanishing Bekenstein-Hawking entropy. They correspond to three (inequivalent) classes of orbits of the charge vector, which is in a 2(n_{V}+1)-dimensional representation $R_{V}$ of the U-duality group. Such orbits are non-degenerate, namely they have non-vanishing quartic invariant (for rank-3 spaces). Other than the 1/2-BPS one, there are two other distinct non-BPS classes of charge orbits, one of which has vanishing central charge. The three species of solutions to the N=2 extremal black hole attractor equations give rise to different mass spectra of the scalar fl...
On the security of 3D Cat map based symmetric image encryption scheme
Energy Technology Data Exchange (ETDEWEB)
Wang Kai [Department of Radio Engineering, Southeast University, Nanjing 210096 (China); Pei, W.-J. [Department of Radio Engineering, Southeast University, Nanjing 210096 (China)]. E-mail: wjpei@seu.edu.cn; Zou, Liuhua [Department of Radio Engineering, Southeast University, Nanjing 210096 (China); Song Aiguo [Department of Instrument Science and Engineering, Southeast University, Nanjing 210096 (China); He Zhenya [Department of Radio Engineering, Southeast University, Nanjing 210096 (China)
2005-08-22
A 3D Cat map based symmetric image encryption algorithm, which significantly increases the resistance against statistical and differential attacks, has been proposed recently. It employs a 3D Cat map to shuffle the positions of image pixels and uses the Logistic map to diffuse the relationship between the cipher-image and the plain-image. Based on the factor that it is sufficient to break this cryptosystem only with the equivalent control parameters, some fundamental weaknesses of the cryptosystem are pointed out. With the knowledge of symbolic dynamics and some specially designed plain-images, we can calculate the equivalent initial condition of diffusion process and rebuild a valid equivalent 3D Cat matrix. In this Letter, we will propose a successful chosen-plain-text cryptanalytic attack, which is composed of two mutually independent procedures: the cryptanalysis of the diffusion process and the cryptanalysis of the spatial permutation process. Both theoretical and experimental results show that the lack of security discourages the use of these cryptosystems for practical applications.
Novel Noncommutative Cryptography Scheme Using Extra Special Group
Gautam Kumar; Hemraj Saini
2017-01-01
Noncommutative cryptography (NCC) is truly a fascinating area with great hope of advancing performance and security for high end applications. It provides a high level of safety measures. The basis of this group is established on the hidden subgroup or subfield problem (HSP). The major focus in this manuscript is to establish the cryptographic schemes on the extra special group (ESG). ESG is showing one of the most appropriate noncommutative platforms for the solution of an open problem. The ...
Secure Dynamic ID-based user authentication scheme using symmetric encryption and smart cards
Martínez-Peláez, Rafael; Universidad de la Salle Bajío; Saavedra-Benítez, Yésica Imelda; Instituto Tecnológico de Toluca; Velarde-Alvarado, Pablo; Ruiz-Ibarra, Joel; Universidad Estatal de Sonora; Toral-Cruz, Homero; Universidad de Quintana Roo; Aguilar-Vargas, Enrique; Universidad de La Salle Bajío
2016-01-01
In 2004, Das, Saxena & Gulati introduced a new scheme called dynamic ID-based with the purpose of avoiding identity theft attack. Since then, many schemes have been proposed with the intention to improve security in different ways. Then, Sood et al. proposed a new scheme and claimed that it is more secure than Liou, Lin & Wang’s scheme. However, cryptanalysis study demonstrates that it is still vulnerable to guessing secret key attack, impersonation attack and steal information from a...
Novel Noncommutative Cryptography Scheme Using Extra Special Group
Directory of Open Access Journals (Sweden)
Gautam Kumar
2017-01-01
Full Text Available Noncommutative cryptography (NCC is truly a fascinating area with great hope of advancing performance and security for high end applications. It provides a high level of safety measures. The basis of this group is established on the hidden subgroup or subfield problem (HSP. The major focus in this manuscript is to establish the cryptographic schemes on the extra special group (ESG. ESG is showing one of the most appropriate noncommutative platforms for the solution of an open problem. The working principle is based on the random polynomials chosen by the communicating parties to secure key exchange, encryption-decryption, and authentication schemes. This group supports Heisenberg, dihedral order, and quaternion group. Further, this is enhanced from the general group elements to equivalent ring elements, known by the monomials generations for the cryptographic schemes. In this regard, special or peculiar matrices show the potential advantages. The projected approach is exclusively based on the typical sparse matrices, and an analysis report is presented fulfilling the central cryptographic requirements. The order of this group is more challenging to assail like length based, automorphism, and brute-force attacks.
Directory of Open Access Journals (Sweden)
Xiaoqiang Di
Full Text Available Both symmetric and asymmetric color image encryption have advantages and disadvantages. In order to combine their advantages and try to overcome their disadvantages, chaos synchronization is used to avoid the key transmission for the proposed semi-symmetric image encryption scheme. Our scheme is a hybrid chaotic encryption algorithm, and it consists of a scrambling stage and a diffusion stage. The control law and the update rule of function projective synchronization between the 3-cell quantum cellular neural networks (QCNN response system and the 6th-order cellular neural network (CNN drive system are formulated. Since the function projective synchronization is used to synchronize the response system and drive system, Alice and Bob got the key by two different chaotic systems independently and avoid the key transmission by some extra security links, which prevents security key leakage during the transmission. Both numerical simulations and security analyses such as information entropy analysis, differential attack are conducted to verify the feasibility, security, and efficiency of the proposed scheme.
Nakayama, Ryohei; Hizukuri, Akiyoshi; Yamamoto, Koji; Nakako, Nobuo; Nagasawa, Naoki; Takeda, Kan
2012-02-01
It is difficult to detect sentinel lymph nodes (SLNs) around an injection point of radiopharmaceuticals mapped in lymphoscintigrams. The purpose of this study was to develop a computer-aided detection (CAD) scheme for SLNs by a subtraction technique using the symmetrical property in the mapped injection point. Our database consisted of 78 lymphoscintigrams with 86 SLNs. In our CAD scheme, the mapped injection point of radiopharmaceuticals was first segmented from the lymphoscintigram using a gray-level thresholding technique. Lymphoscintigram was then divided into four regions by vertical and horizontal straight lines through the center of the segmented injection point. One of the four divided regions was defined as the target region. The correlation coefficients based on pixel values were calculated between the target region and each of the other three regions. The region with the highest correlation coefficient among three regions was selected as the similar region to the target region. The values of pixels on the target region were subtracted by the values of the corresponding pixels on the similar region. This procedure was repeated until every divided region had been used as target region. SLNs were segmented by applying a gray-level thresholding technique to the subtracted image. With our CAD scheme, sensitivity and the number of false positives were 95.3% (82/86) and 2.51 per image, respectively. Our CAD scheme achieved a high level of detection accuracy, and would have a great potential in assisting physicians to detect SLNs in lymphoscintigrams.
Sirenko, Kostyantyn
2011-01-01
An accurate and efficient finite-difference time-domain (FDTD) method for characterizing transient waves interactions on axially symmetric structures is presented. The method achieves its accuracy and efficiency by employing localized and/or fast Fourier transform (FFT) accelerated exact absorbing conditions (EACs). The paper details the derivation of the EACs, discusses their implementation and discretization in an FDTD method, and proposes utilization of a blocked-FFT based algorithm for accelerating the computation of temporal convolutions present in nonlocal EACs. The proposed method allows transient analyses to be carried for long time intervals without any loss of accuracy and provides reliable numerical data pertinent to physical processes under resonant conditions. This renders the method highly useful in characterization of high-Q microwave radiators and energy compressors. Numerical results that demonstrate the accuracy and efficiency of the method are presented.
A Symmetric RZ-DPSK Based Colorless NG-PON using Optical Carrier Suppression Scheme
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AFTAB HUSSAIN
2017-01-01
Full Text Available In this paper a simultaneous transmission of a 10 Gbps RZ-DPSK data signal for downstream as well as for upstream is proposed and successfully simulated. An OCS (Optical Carrier Suppression scheme for generation of second order dual side-band optical carrier is utilized by quadrupling a 10 GHz clockfrequency with a 10 GHz LN-MZM (Lithium-Niobate Mach-Zehnder-Modulator. The upper side second order band is used to generate a RZ-DPSK (Return to Zero-Differential Phase Shift Keying data signal at the OLT (Optical Line Terminal. At the receiving ONU (Optical Network Unit 50 km away from the OLT the unmodulated lower side second order band coupled with the downlink transmitted signal is utilized for the uplink modulation of 10 Gbps data in RZ-DPSK format. The simulation results show that the performance of the single-tone RZ-DPSK data modulation format is a suitable choice for the WDMPON (Wavelength Division Multiplexing-Passive Optical Network link with a transmission span of 50 km. The proposed architecture eliminates the need of any pulse carver and mid-span power amplifiers along with the requirement of any power splitting device used in the ONU for colorless uplink transmission. In this scheme, high data rate transmission over long distance is achieved. This scheme merges the boundaries of local access networks and MAN (Metropolitan Area Networks. The proposed scheme is a highly robust, cost effective, backward compatible as well as future proof WDM-PON architecture.
Hampel, Uwe; Freyer, Richard
1996-12-01
We present a reconstruction scheme which solves the inverse linear problem in optical absorption tomography for radially symmetric objects. This is a relevant geometry for optical diagnosis in soft tissues, e.g. breast, testis and even head. The algorithm utilizes an invariance property of the linear imaging operator in homogeneously scattering media. The inverse problem is solved in the Fourier space of the angular component leading to a considerable dimension reduction which allows to compute the inverse in a direct way using singular value decomposition. There are two major advantages of this approach. First the inverse operator can be stored in computer memory and the computation of the inverse problem comprises only a few matrix multiplications. This makes the algorithm very fast and suitable for parallel execution. On the other hand we obtain the spectrum of the imaging operator that allows conclusions about reconstruction limits in the presence of noise and gives a termination criterion for image synthesis. To demonstrate the capabilities of this scheme reconstruction results from synthetic and phantom data are presented.
Directory of Open Access Journals (Sweden)
B. ZHANG
2012-12-01
Full Text Available This paper is concerned with a rate-splitting based transmission strategy for the two-user symmetric Gaussian interference channel that contains common messages only. Each transmitter encodes its common message into multiple layers by multiple codebooks that drawn from one separate code book, and transmits the superposition of the messages corresponding to these layers; each receiver decodes the messages from all layers of the two users successively. Two schemes are proposed for decoding order and optimal power allocation among layers respectively. With the proposed decoding order scheme, the sum-rate can be increased by rate-splitting, especially at the optimal number of rate-splitting, using average power allocation in moderate and weak interference regime. With the two proposed schemes at the receiver and the transmitter respectively, the sum-rate achieves the inner bound of HK without time-sharing. Numerical results show that the proposed optimal power allocation scheme with the proposed decoding order can achieve significant improvement of the performance over equal power allocation, and achieve the sum-rate within two bits per channel use (bits/channel use of the sum capacity.
Application of Central Upwind Scheme for Solving Special Relativistic Hydrodynamic Equations
Yousaf, Muhammad; Ghaffar, Tayabia; Qamar, Shamsul
2015-01-01
The accurate modeling of various features in high energy astrophysical scenarios requires the solution of the Einstein equations together with those of special relativistic hydrodynamics (SRHD). Such models are more complicated than the non-relativistic ones due to the nonlinear relations between the conserved and state variables. A high-resolution shock-capturing central upwind scheme is implemented to solve the given set of equations. The proposed technique uses the precise information of local propagation speeds to avoid the excessive numerical diffusion. The second order accuracy of the scheme is obtained with the use of MUSCL-type initial reconstruction and Runge-Kutta time stepping method. After a discussion of the equations solved and of the techniques employed, a series of one and two-dimensional test problems are carried out. To validate the method and assess its accuracy, the staggered central and the kinetic flux-vector splitting schemes are also applied to the same model. The scheme is robust and efficient. Its results are comparable to those obtained from the sophisticated algorithms, even in the case of highly relativistic two-dimensional test problems. PMID:26070067
Kiely, A; O'Meara, S; Fitzgerald, N; Regan, A M; Durcan, P; McGuire, G; Kelly, M E
2017-03-10
The Special Type Consultation (STC) scheme is a fee-for-service reimbursement scheme for General Practitioners (GPs) in Ireland. Introduced in 1989, the scheme includes specified patient services involving the application of a learned skill, e.g. suturing. This study aims to establish the extent to which GPs believe this scheme is appropriate for current General Practice. This is an embedded mixed-methods study combining quantitative data on GPs working experience of and qualitative data on GPs attitudes towards the scheme. Data were collected by means of an anonymous postal questionnaire. The response rate was 60.4% (n=159.) Twenty-nine percent (n=46) disagreed and 65% (n=104) strongly disagreed that the current list of special items is satisfactory. Two overriding themes were identified: economics and advancement of the STC process. This study demonstrates an overwhelming consensus among GPs that the current STC scheme is outdated and in urgent need of revision to reflect modern General Practice.
LENUS (Irish Health Repository)
Kiely, A
2017-03-01
The Special Type Consultation (STC) scheme is a fee-for-service reimbursement scheme for General Practitioners (GPs) in Ireland. Introduced in 1989, the scheme includes specified patient services involving the application of a learned skill, e.g. suturing. This study aims to establish the extent to which GPs believe this scheme is appropriate for current General Practice. This is an embedded mixed-methods study combining quantitative data on GPs working experience of and qualitative data on GPs attitudes towards the scheme. Data were collected by means of an anonymous postal questionnaire. The response rate was 60.4% (n=159.) Twenty-nine percent (n=46) disagreed and 65% (n=104) strongly disagreed that the current list of special items is satisfactory. Two overriding themes were identified: economics and advancement of the STC process. This study demonstrates an overwhelming consensus among GPs that the current STC scheme is outdated and in urgent need of revision to reflect modern General Practice.
Energy Technology Data Exchange (ETDEWEB)
Clarisse, J.M
2007-07-01
A numerical scheme for computing linear Lagrangian perturbations of spherically symmetric flows of gas dynamics is proposed. This explicit first-order scheme uses the Roe method in Lagrangian coordinates, for computing the radial spherically symmetric mean flow, and its linearized version, for treating the three-dimensional linear perturbations. Fulfillment of the geometric conservation law discrete formulations for both the mean flow and its perturbation is ensured. This scheme capabilities are illustrated by the computation of free-surface mode evolutions at the boundaries of a spherical hollow shell undergoing an homogeneous cumulative compression, showing excellent agreement with reference results. (author)
a Cumulus Parameterization Study with Special Attention to the Arakawa-Schubert Scheme
Kao, Chih-Yue Jim
Arakawa and Schubert (1974) developed a cumulus parameterization scheme in a framework that conceptually divides the mutual interaction of the cumulus convection and large-scale disturbance into the categories of large -scale budget requirements and the quasi-equilibrium assumption of cloud work function. We have applied the A-S scheme through a semi-prognostic approach to two different data sets: one is for an intense tropical cloud band event; the other is for tropical composite easterly wave disturbances. Both were observed in GATE. The cloud heating and drying effects predicted by the Arakawa-Schubert scheme are found to agree rather well with the observations. However, it is also found that the Arakawa-Schubert scheme underestimates both condensation and evaporation rates substantially when compared with the cumulus ensemble model results (Soong and Tao, 1980; Tao, 1983). An inclusion of the downdraft effects, as formulated by Johnson (1976), appears to alleviate this deficiency. In order to examine how the Arakawa-Schubert scheme works in a fully prognostic problem, a simulation of the evolution and structure of the tropical cloud band, mentioned above, under the influence of an imposed large-scale low -level forcing has been made, using a two-dimensional hydrostatic model with the inclusion of the Arakawa-Schubert scheme. Basically, the model result indicates that the meso-scale convective system is driven by the excess of the convective heating derived from the Arakawa-Schubert scheme over the adiabatic cooling due to the imposed large-scale lifting and induced meso-scale upward motion. However, as the convective system develops, the adiabatic warming due to the subsidence outside the cloud cluster gradually accumulates into a secondary temperature anomaly which subsequently reduces the original temperature contrast and inhibits the further development of the convective system. A 24 hour integration shows that the model is capable of simulating many
Mickens, R. E.
1984-01-01
Work on the construction of finite difference models of differential equations having zero truncation errors is summarized. Both linear and nonlinear unidirectional wave equations are discussed. Results regarding the construction of zero truncation error schemes for the full wave equation and Burger's equation are also briefly reported.
DEFF Research Database (Denmark)
Liu, Zhou
the proposed protection strategy in this thesis, a real time simulation platform based on Real Time Digital Simulator (RTDS) and LabVIEW is built. In this platform, the cases of cascaded blackouts are simulated on the test system simplified from the East Denmark power system. For the MAS based control system......, the distributed power system agents are set up in RTDS, while the agents in higher level are designed by LabVIEW toolkits. The case studies and simulation results demonstrate the effectiveness of real time application of the proposed MAS based special protection and emergency control scheme against the cascaded...
Preface to the special issue on next-generation multiplexing schemes in fiber-based systems
Sillard, Pierre; Essiambre, René-Jean; Jung, Yongmin; Yamamoto, Takashi
2017-02-01
Since the beginning of optical communications in the late 70s, capacity has kept up with the exponential growth of traffic demand. This has been enabled by many technologies among which the most up-to-date wavelength multiplexing combined with coherent detection of polarized-multiplexed quadrature-amplitude-modulated signals. There is, however, a growing realization that this might no longer be sufficient and that next-generation multiplexing schemes are needed to avoid an imminent capacity crunch.
Directory of Open Access Journals (Sweden)
NICOLAE ECOBICI
2010-01-01
Full Text Available In the same time with the crisis deepening in Romania, pawn businessesare also growing. In this paper we discussed several issues concerning the choice of the schemeof registration and determination of value added tax at Pawn Shops, together with the tax andaccounting implications of this choice. Therefore, we presented the theoretical aspectsregarding the likelihood of Pawn Shops to choose the special scheme for second-hand goods, asthey are covered by the Fiscal Code. At the end of this paper we presented based on an examplethe tax and accounting implications of such special scheme as compared with the “normal”scheme regarding VAT at the Pawn Shops in Romania.
Matsui, Ryosuke
2013-01-01
This paper intends to review the historical development and related issues involved in the employment of persons with disabilities under the Law on Employment Promotion of Persons with Disabilities in Japan in light of the UN Convention on the Rights of Persons with Disabilities (CRPD). The actual situations of the special subsidiary company system, which was established by the Law to assist large-sized enterprises in achieving their legally mandated quota, were analyzed, based on the relevant data and materials published by the government and other sources. The targeted enterprises could achieve the highest employment rates of persons with disabilities through the establishment of special subsidiary companies. However, various studies on these companies have revealed that more effort is needed to improve the quality of employment of their workers with disabilities in light of the UN Convention on the Rights of Persons with Disabilities (CRPD).
DEFF Research Database (Denmark)
Ciontea, Catalin-Iosif; Bak, Claus Leth; Blaabjerg, Frede
2017-01-01
Distribution networks are evolving toward the vision of microgrids, which are defined as power systems that contain both loads and Distributed Energy Resources and operate in a grid-connected or islanded mode. Correct operation of the OverCurrent protection is compromised in a typical microgrid...... Medium Voltage microgrid using PSCAD and simulation results prove its effectiveness against various Single Phase to Ground faults. The proposed method solves some of the protection issues associated with a high penetration level of Distributed Generation, as it is less sensitive to the variable short...... because the fault current is significantly lower in the islanded mode compared to the grid-connected mode and consequently a single set of settings for the OC relays is not sufficient. This paper propose a communication-assisted protection scheme that is able to operate correctly in a radial Medium...
Symmetric Key Authentication Services Revisited
Crispo, B.; Popescu, B.C.; Tanenbaum, A.S.
2004-01-01
Most of the symmetric key authentication schemes deployed today are based on principles introduced by Needham and Schroeder [15] more than twenty years ago. However, since then, the computing environment has evolved from a LAN-based client-server world to include new paradigms, including wide area
SPECIAL ASPECTS OF INITIAL OPTICAL SCHEME SELECTION FOR DESIGN OF NON-IMAGING OPTICAL SYSTEMS
Directory of Open Access Journals (Sweden)
R. V. Anitropov
2016-01-01
system for surgical room was obtained, consisting of three identical domes. The illuminator designed with the use of the proposed methodology showed high energy efficiency (92.3%. Practical Relevance. The results can find application in optical design of non-imaging systems having various functionality, for example, illuminators, concentrators, etc. and can provide import substitution of similar foreign devices. The results can be useful by engineers specializing in the design and/or operation of non-imaging optical systems.
Energy Technology Data Exchange (ETDEWEB)
Kachel, Markus [Becker Buettner Held Rechtsanwaelte Wirtschaftspruefer Steuerberater, Berlin (Germany)
2012-07-01
The special equalisation scheme in Sects. 50 ff EEG is a very important tool for industrial policy in Germany. The regulations have significantly reduced the power acquisition cost of the privileged organisations and will be further enhanced from 2013. The contribution describes the changes and discusses new and older legal problems occurring in practice.
Directory of Open Access Journals (Sweden)
Hajdukiewicz Agnieszka
2014-06-01
Full Text Available The schemes for identifying and protecting the names of agricultural products and foods having specific qualities, have been launched by European Union as a part of its complex agricultural quality policy. The main objective of this article is to examine different aspects of three of the schemes, developed for products with specific characteristics resulting from a particular origin or farming method: PDO (Protected Designation of Origin, PGI (Protected Geographical Indication and TSG (Traditional Speciality Guarantied. The focus is mainly on the economic issues of the production and marketing of products and foodstuffs registered under particular schemes. The methodology includes studying the existing literature and European regulations on the subject, collecting and analysing statistical data as well as examining a short practical case.
Olafsson, Gestur; Helgason, Sigurdur
1996-01-01
This book is intended to introduce researchers and graduate students to the concepts of causal symmetric spaces. To date, results of recent studies considered standard by specialists have not been widely published. This book seeks to bring this information to students and researchers in geometry and analysis on causal symmetric spaces.Includes the newest results in harmonic analysis including Spherical functions on ordered symmetric space and the holmorphic discrete series and Hardy spaces on compactly casual symmetric spacesDeals with the infinitesimal situation, coverings of symmetric spaces, classification of causal symmetric pairs and invariant cone fieldsPresents basic geometric properties of semi-simple symmetric spacesIncludes appendices on Lie algebras and Lie groups, Bounded symmetric domains (Cayley transforms), Antiholomorphic Involutions on Bounded Domains and Para-Hermitian Symmetric Spaces
Jiang, Haiyong
2016-04-11
We present an automatic algorithm for symmetrizing facade layouts. Our method symmetrizes a given facade layout while minimally modifying the original layout. Based on the principles of symmetry in urban design, we formulate the problem of facade layout symmetrization as an optimization problem. Our system further enhances the regularity of the final layout by redistributing and aligning boxes in the layout. We demonstrate that the proposed solution can generate symmetric facade layouts efficiently. © 2015 IEEE.
Symmetrization of Facade Layouts
Jiang, Haiyong
2016-02-26
We present an automatic approach for symmetrizing urban facade layouts. Our method can generate a symmetric layout through minimally modifying the original input layout. Based on the principles of symmetry in urban design, we formulate facade layout symmetrization as an optimization problem. Our method further enhances the regularity of the final layout by redistributing and aligning elements in the layout. We demonstrate that the proposed solution can effectively generate symmetric facade layouts.
Sman, van der R.G.M.
2006-01-01
In the special case of relaxation parameter = 1 lattice Boltzmann schemes for (convection) diffusion and fluid flow are equivalent to finite difference/volume (FD) schemes, and are thus coined finite Boltzmann (FB) schemes. We show that the equivalence is inherent to the homology of the
A branch-and-cut algorithm for the symmetric two-echelon capacitated vehicle routing problem
DEFF Research Database (Denmark)
Jepsen, Mads Kehlet; Spoorendonk, Simon; Røpke, Stefan
2013-01-01
This paper presents an exact method for solving the symmetric two-echelon capacitated vehicle routing problem, a transportation problem concerned with the distribution of goods from a depot to a set of customers through a set of satellite locations. The presented method is based on an edge flow...... model that is a relaxation and provides a valid lower bound. A specialized branching scheme is employed to obtain feasible solutions. Out of a test set of 93 instances the algorithm is able to solve 47 to optimality surpassing previous exact algorithms....
Symmetric cryptographic protocols
Ramkumar, Mahalingam
2014-01-01
This book focuses on protocols and constructions that make good use of symmetric pseudo random functions (PRF) like block ciphers and hash functions - the building blocks for symmetric cryptography. Readers will benefit from detailed discussion of several strategies for utilizing symmetric PRFs. Coverage includes various key distribution strategies for unicast, broadcast and multicast security, and strategies for constructing efficient digests of dynamic databases using binary hash trees. • Provides detailed coverage of symmetric key protocols • Describes various applications of symmetric building blocks • Includes strategies for constructing compact and efficient digests of dynamic databases
On the symmetric α-stable distribution with application to symbol error rate calculations
Soury, Hamza
2016-12-24
The probability density function (PDF) of the symmetric α-stable distribution is investigated using the inverse Fourier transform of its characteristic function. For general values of the stable parameter α, it is shown that the PDF and the cumulative distribution function of the symmetric stable distribution can be expressed in terms of the Fox H function as closed-form. As an application, the probability of error of single input single output communication systems using different modulation schemes with an α-stable perturbation is studied. In more details, a generic formula is derived for generalized fading distribution, such as the extended generalized-k distribution. Later, simpler expressions of these error rates are deduced for some selected special cases and compact approximations are derived using asymptotic expansions.
Substring-Searchable Symmetric Encryption
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Chase Melissa
2015-06-01
Full Text Available In this paper, we consider a setting where a client wants to outsource storage of a large amount of private data and then perform substring search queries on the data – given a data string s and a search string p, find all occurrences of p as a substring of s. First, we formalize an encryption paradigm that we call queryable encryption, which generalizes searchable symmetric encryption (SSE and structured encryption. Then, we construct a queryable encryption scheme for substring queries. Our construction uses suffix trees and achieves asymptotic efficiency comparable to that of unencrypted suffix trees. Encryption of a string of length n takes O(λn time and produces a ciphertext of size O(λn, and querying for a substring of length m that occurs k times takes O(λm+k time and three rounds of communication. Our security definition guarantees correctness of query results and privacy of data and queries against a malicious adversary. Following the line of work started by Curtmola et al. (ACM CCS 2006, in order to construct more efficient schemes we allow the query protocol to leak some limited information that is captured precisely in the definition. We prove security of our substring-searchable encryption scheme against malicious adversaries, where the query protocol leaks limited information about memory access patterns through the suffix tree of the encrypted string.
Directory of Open Access Journals (Sweden)
Xuefeng Zhu
2014-09-01
Full Text Available We introduce here the concept of acoustic parity-time (PT symmetry and demonstrate the extraordinary scattering characteristics of the acoustic PT medium. On the basis of exact calculations, we show how an acoustic PT-symmetric medium can become unidirectionally transparent at given frequencies. Combining such a PT-symmetric medium with transformation acoustics, we design two-dimensional symmetric acoustic cloaks that are unidirectionally invisible in a prescribed direction. Our results open new possibilities for designing functional acoustic devices with directional responses.
Plane Symmetric Cosmological Model with Quark and Strange ...
Indian Academy of Sciences (India)
Abstract. We studied plane symmetric cosmological model in the presence of quark and strange quark mat- ter with the help of f(R, T) theory. To decipher solutions of plane symmetric space-time, we used power law relation between scale factor and deceleration parameter. We considered the special law of variation of.
Minimal surfaces in symmetric spaces with parallel second ...
Indian Academy of Sciences (India)
Xiaoxiang Jiao
2017-07-31
Jul 31, 2017 ... surfaces, both in a symmetric space and a complex two-dimensional Kähler symmetric space. Here we use a general moving frame, not a Darboux frame. It is an interesting problem to study parallel submanifolds in a special Riemannian sym- metric space. In fact, these submanifolds have been discussed ...
Counting with symmetric functions
Mendes, Anthony
2015-01-01
This monograph provides a self-contained introduction to symmetric functions and their use in enumerative combinatorics. It is the first book to explore many of the methods and results that the authors present. Numerous exercises are included throughout, along with full solutions, to illustrate concepts and also highlight many interesting mathematical ideas. The text begins by introducing fundamental combinatorial objects such as permutations and integer partitions, as well as generating functions. Symmetric functions are considered in the next chapter, with a unique emphasis on the combinatorics of the transition matrices between bases of symmetric functions. Chapter 3 uses this introductory material to describe how to find an assortment of generating functions for permutation statistics, and then these techniques are extended to find generating functions for a variety of objects in Chapter 4. The next two chapters present the Robinson-Schensted-Knuth algorithm and a method for proving Pólya’s enu...
Symmetric Tensor Decomposition
DEFF Research Database (Denmark)
Brachat, Jerome; Comon, Pierre; Mourrain, Bernard
2010-01-01
We present an algorithm for decomposing a symmetric tensor, of dimension n and order d, as a sum of rank-1 symmetric tensors, extending the algorithm of Sylvester devised in 1886 for binary forms. We recall the correspondence between the decomposition of a homogeneous polynomial in n variables....... Exploiting this duality, we propose necessary and sufficient conditions for the existence of such a decomposition of a given rank, using the properties of Hankel (and quasi-Hankel) matrices, derived from multivariate polynomials and normal form computations. This leads to the resolution of systems...
Symmetric Spaces in Supergravity
Ferrara, Sergio
2008-01-01
We exploit the relation among irreducible Riemannian globally symmetric spaces (IRGS) and supergravity theories in 3, 4 and 5 space-time dimensions. IRGS appear as scalar manifolds of the theories, as well as moduli spaces of the various classes of solutions to the classical extremal black hole Attractor Equations. Relations with Jordan algebras of degree three and four are also outlined.
Energy Technology Data Exchange (ETDEWEB)
Amore, Paolo, E-mail: paolo.amore@gmail.com [Facultad de Ciencias, CUICBAS, Universidad de Colima, Bernal Díaz del Castillo 340, Colima, Colima (Mexico); Fernández, Francisco M., E-mail: fernande@quimica.unlp.edu.ar [INIFTA (UNLP, CCT La Plata-CONICET), División Química Teórica, Diag. 113 y 64 (S/N), Sucursal 4, Casilla de Correo 16, 1900 La Plata (Argentina); Garcia, Javier [INIFTA (UNLP, CCT La Plata-CONICET), División Química Teórica, Diag. 113 y 64 (S/N), Sucursal 4, Casilla de Correo 16, 1900 La Plata (Argentina); Gutierrez, German [Facultad de Ciencias, CUICBAS, Universidad de Colima, Bernal Díaz del Castillo 340, Colima, Colima (Mexico)
2014-04-15
We study both analytically and numerically the spectrum of inhomogeneous strings with PT-symmetric density. We discuss an exactly solvable model of PT-symmetric string which is isospectral to the uniform string; for more general strings, we calculate exactly the sum rules Z(p)≡∑{sub n=1}{sup ∞}1/E{sub n}{sup p}, with p=1,2,… and find explicit expressions which can be used to obtain bounds on the lowest eigenvalue. A detailed numerical calculation is carried out for two non-solvable models depending on a parameter, obtaining precise estimates of the critical values where pair of real eigenvalues become complex. -- Highlights: •PT-symmetric Hamiltonians exhibit real eigenvalues when PT symmetry is unbroken. •We study PT-symmetric strings with complex density. •They exhibit regions of unbroken PT symmetry. •We calculate the critical parameters at the boundaries of those regions. •There are exact real sum rules for some particular complex densities.
Homogenous finitary symmetric groups
Directory of Open Access Journals (Sweden)
Otto. H. Kegel
2015-03-01
Full Text Available We characterize strictly diagonal type of embeddings of finitary symmetric groups in terms of cardinality and the characteristic. Namely, we prove the following. Let kappa be an infinite cardinal. If G=underseti=1stackrelinftybigcupG i , where G i =FSym(kappan i , (H=underseti=1stackrelinftybigcupH i , where H i =Alt(kappan i , is a group of strictly diagonal type and xi=(p 1 ,p 2 ,ldots is an infinite sequence of primes, then G is isomorphic to the homogenous finitary symmetric group FSym(kappa(xi (H is isomorphic to the homogenous alternating group Alt(kappa(xi , where n 0 =1,n i =p 1 p 2 ldotsp i .
Chen, Yan; Feng, Huijuan; Ma, Jiayao; Peng, Rui; You, Zhong
2016-06-01
The traditional waterbomb origami, produced from a pattern consisting of a series of vertices where six creases meet, is one of the most widely used origami patterns. From a rigid origami viewpoint, it generally has multiple degrees of freedom, but when the pattern is folded symmetrically, the mobility reduces to one. This paper presents a thorough kinematic investigation on symmetric folding of the waterbomb pattern. It has been found that the pattern can have two folding paths under certain circumstance. Moreover, the pattern can be used to fold thick panels. Not only do the additional constraints imposed to fold the thick panels lead to single degree of freedom folding, but the folding process is also kinematically equivalent to the origami of zero-thickness sheets. The findings pave the way for the pattern being readily used to fold deployable structures ranging from flat roofs to large solar panels.
Porcine focal symmetrical poliomyelomalacia.
Wilson, T.M.; Drake, T R
1982-01-01
An acute afebrile paretic condition was diagnosed in 16 of 100 feeder pigs between eight to ten weeks of age. Nine pigs died acutely and seven pigs were euthanized. Macroscopic lesions in the ventral horns of the cervical, thoracic, lumbar and sacral segments of the spinal cord consisted of focal, bilateral, grey depressed areas. There was a bilateral symmetrical focal poliomyelomalacia histopathologically characterized by microcavitation, endothelial and glial cell proliferation and infiltra...
Design and Analysis of Symmetric Primitives
DEFF Research Database (Denmark)
Lauridsen, Martin Mehl
The subject of this thesis is the study of symmetric cryptographic primitives. We investigate these objects from three different perspectives: cryptanalysis, design and implementation aspects. The first part deals with cryptanalysis of symmetric primitives, where one tries to leverage a property...... of the design to achieve some adversarial goal. Two of the most successful types of cryptanalysis are differential- and linear attacks. We apply variants of differential cryptanalysis to the lightweight block cipher SIMON which was proposed by researchers from the National Security Agency (NSA) in 2013...... linear cryptanalysis. We apply this model to the standardized block cipher PRESENT. Finally, we present very generic attacks on two authenticated encryption schemes, AVALANCHE and RBS, by pointing out severe design flaws that can be leveraged to fully recover the secret key with very low complexity...
Symmetrization of binary random variables
Kagan, Abram; Mallows, Colin L.; Shepp, Larry A.; Vanderbei, Robert J.; Vardi, Yehuda
1999-01-01
A random variable [math] is called an independent symmetrizer of a given random variable [math] if (a) it is independent of [math] and (b) the distribution of [math] is symmetric about [math] . In cases where the distribution of [math] is symmetric about its mean, it is easy to see that the constant random variable [math] is a minimum-variance independent symmetrizer. Taking [math] to have the same distribution as [math] clearly produces a symmetric sum, but it may not be of minimum variance....
Porcine focal symmetrical poliomyelomalacia.
Wilson, T M; Drake, T R
1982-04-01
An acute afebrile paretic condition was diagnosed in 16 of 100 feeder pigs between eight to ten weeks of age. Nine pigs died acutely and seven pigs were euthanized. Macroscopic lesions in the ventral horns of the cervical, thoracic, lumbar and sacral segments of the spinal cord consisted of focal, bilateral, grey depressed areas. There was a bilateral symmetrical focal poliomyelomalacia histopathologically characterized by microcavitation, endothelial and glial cell proliferation and infiltration of eosinophils. Clinical and pathological findings resemble spontaneous and experimental lesions associated with acute nicotinamide deficiency and selenium toxicosis in swine.
An Optimal Symmetric Secret Distribution of Star Networks
2007-01-01
instantiation in ad-hoc networks. Computer Comunications , (29):200–215, 2006. [5] Aiyer A.S., Alvisi L, and Gouda M. G. Key grids: A protocol family for...assigning symmetric keys. In IEEE International Conference on Network Protocols, 2006. [6] Eschenauer L and Gligor V. D. A key- management scheme for
Box-Cox symmetric distributions and applications to nutritional data
Ferrari, Silvia L. P.; Fumes, Giovana
2016-01-01
We introduce the Box-Cox symmetric class of distributions, which is useful for modeling positively skewed, possibly heavy-tailed, data. The new class of distributions includes the Box-Cox t, Box-Cox Cole-Gree, Box-Cox power exponential distributions, and the class of the log-symmetric distributions as special cases. It provides easy parameter interpretation, which makes it convenient for regression modeling purposes. Additionally, it provides enough flexibility to handle outliers. The usefuln...
Directory of Open Access Journals (Sweden)
Giuseppe Di Maio
2008-04-01
Full Text Available The subject of hyperspace topologies on closed or closed and compact subsets of a topological space X began in the early part of the last century with the discoveries of Hausdorff metric and Vietoris hit-and-miss topology. In course of time, several hyperspace topologies were discovered either for solving some problems in Applied or Pure Mathematics or as natural generalizations of the existing ones. Each hyperspace topology can be split into a lower and an upper part. In the upper part the original set inclusion of Vietoris was generalized to proximal set inclusion. Then the topologization of the Wijsman topology led to the upper Bombay topology which involves two proximities. In all these developments the lower topology, involving intersection of finitely many open sets, was generalized to locally finite families but intersection was left unchanged. Recently the authors studied symmetric proximal topology in which proximity was used for the first time in the lower part replacing intersection with its generalization: nearness. In this paper we use two proximities also in the lower part and we obtain the lower Bombay hypertopology. Consequently, a new hypertopology arises in a natural way: the symmetric Bombay topology which is the join of a lower and an upper Bombay topology.
Holographic Spherically Symmetric Metrics
Petri, Michael
The holographic principle (HP) conjectures, that the maximum number of degrees of freedom of any realistic physical system is proportional to the system's boundary area. The HP has its roots in the study of black holes. It has recently been applied to cosmological solutions. In this article we apply the HP to spherically symmetric static space-times. We find that any regular spherically symmetric object saturating the HP is subject to tight constraints on the (interior) metric, energy-density, temperature and entropy-density. Whenever gravity can be described by a metric theory, gravity is macroscopically scale invariant and the laws of thermodynamics hold locally and globally, the (interior) metric of a regular holographic object is uniquely determined up to a constant factor and the interior matter-state must follow well defined scaling relations. When the metric theory of gravity is general relativity, the interior matter has an overall string equation of state (EOS) and a unique total energy-density. Thus the holographic metric derived in this article can serve as simple interior 4D realization of Mathur's string fuzzball proposal. Some properties of the holographic metric and its possible experimental verification are discussed. The geodesics of the holographic metric describe an isotropically expanding (or contracting) universe with a nearly homogeneous matter-distribution within the local Hubble volume. Due to the overall string EOS the active gravitational mass-density is zero, resulting in a coasting expansion with Ht = 1, which is compatible with the recent GRB-data.
Saccades during symmetrical vergence.
Coubard, Olivier A; Kapoula, Zoï
2008-04-01
When the eyes verge symmetrically along the median plane from far to near (convergence) or near to far (divergence), small saccades often occur. The current study aimed to: (i) characterize saccades during symmetrical vergence, (ii) describe the chronometry of saccade relative to that of vergence, and (iii) determine whether saccades mediate prefrontal control of vergence. In Experiment 1, we recorded horizontal saccades during vergence in ten normals using an infrared tracker. Transcranial magnetic stimulation (TMS) was delivered over dorsolateral prefrontal cortex to assess its contribution in saccade production. In Experiment 2, saccades during vergence were recorded in horizontal and vertical planes in two other normals using a video-based tracker. Horizontal saccades, either pure or oblique (Exp.1), occurred in 84.0% of trials, 58 ms after vergence onset, and averaged 1.5 degrees in amplitude. An idiosyncratic directional bias to the right was found for the rate and the latency of saccades. Prefrontal TMS had no influence on any saccade parameter. Pure horizontal, pure vertical and oblique saccades (Exp.2) occurred, respectively, in 60.4%, 72.4% and 25.4% of trials, 168 ms, 121 ms and 146 ms after vergence onset, averaging 1.1 degrees , 1.2 degrees and 1.5 degrees in amplitude. Chronometry of saccades during vergence suggests that they do not participate to vergence triggering, and that prefrontal control of vergence previously reported was not mediated by saccades.
Detecting internally symmetric protein structures
Directory of Open Access Journals (Sweden)
Basner Jodi
2010-06-01
Full Text Available Abstract Background Many functional proteins have a symmetric structure. Most of these are multimeric complexes, which are made of non-symmetric monomers arranged in a symmetric manner. However, there are also a large number of proteins that have a symmetric structure in the monomeric state. These internally symmetric proteins are interesting objects from the point of view of their folding, function, and evolution. Most algorithms that detect the internally symmetric proteins depend on finding repeating units of similar structure and do not use the symmetry information. Results We describe a new method, called SymD, for detecting symmetric protein structures. The SymD procedure works by comparing the structure to its own copy after the copy is circularly permuted by all possible number of residues. The procedure is relatively insensitive to symmetry-breaking insertions and deletions and amplifies positive signals from symmetry. It finds 70% to 80% of the TIM barrel fold domains in the ASTRAL 40 domain database and 100% of the beta-propellers as symmetric. More globally, 10% to 15% of the proteins in the ASTRAL 40 domain database may be considered symmetric according to this procedure depending on the precise cutoff value used to measure the degree of perfection of the symmetry. Symmetrical proteins occur in all structural classes and can have a closed, circular structure, a cylindrical barrel-like structure, or an open, helical structure. Conclusions SymD is a sensitive procedure for detecting internally symmetric protein structures. Using this procedure, we estimate that 10% to 15% of the known protein domains may be considered symmetric. We also report an initial, overall view of the types of symmetries and symmetric folds that occur in the protein domain structure universe.
1991-01-01
their Butterfly Scheme Reference, and to Margaret O’Connell for translating it from BBN’s text-formatting language to ours. Special thanks to Richard ... Stallman , Bob Chassell, and Brian Fox, all of the Free Software Foundation, for creating and maintaining the Texinfo formatting language in which this
Minimally symmetric Higgs boson
Energy Technology Data Exchange (ETDEWEB)
Low, Ian
2015-06-01
Models addressing the naturalness of a light Higgs boson typically employ symmetries, either bosonic or fermionic, to stabilize the Higgs mass. We consider a setup with the minimal amount of symmetries: four shift symmetries acting on the four components of the Higgs doublet, subject to the constraints of linearly realized SU(2)(L) x U(1)(Y) electroweak symmetry. Up to terms that explicitly violate the shift symmetries, the effective Lagrangian can be derived, irrespective of the spontaneously broken group G in the ultraviolet, and is universal among all models where the Higgs arises as a pseudo-Nambu-Goldstone boson. Very high energy scatterings of vector bosons could provide smoking gun signals of a minimally symmetric Higgs boson.
Baryon symmetric big bang cosmology
Stecker, F. W.
1978-01-01
Both the quantum theory and Einsteins theory of special relativity lead to the supposition that matter and antimatter were produced in equal quantities during the big bang. It is noted that local matter/antimatter asymmetries may be reconciled with universal symmetry by assuming (1) a slight imbalance of matter over antimatter in the early universe, annihilation, and a subsequent remainder of matter; (2) localized regions of excess for one or the other type of matter as an initial condition; and (3) an extremely dense, high temperature state with zero net baryon number; i.e., matter/antimatter symmetry. Attention is given to the third assumption, which is the simplest and the most in keeping with current knowledge of the cosmos, especially as pertains the universality of 3 K background radiation. Mechanisms of galaxy formation are discussed, whereby matter and antimatter might have collided and annihilated each other, or have coexisted (and continue to coexist) at vast distances. It is pointed out that baryon symmetric big bang cosmology could probably be proved if an antinucleus could be detected in cosmic radiation.
Directory of Open Access Journals (Sweden)
Giuseppe Dattoli
1996-05-01
Full Text Available q analog of bessel functions, symmetric under the interchange of q and q^ −1 are introduced. The definition is based on the generating function realized as product of symmetric q-exponential functions with appropriate arguments. Symmetric q-Bessel function are shown to satisfy various identities as well as second-order q-differential equations, which in the limit q → 1 reproduce those obeyed by the usual cylindrical Bessel functions. A brief discussion on the possible algebraic setting for symmetric q-Bessel functions is also provided.
DEFF Research Database (Denmark)
Juhl, Hans Jørn; Stacey, Julia
2001-01-01
It is usual practice to evaluate the success of a labelling scheme by looking at the awareness percentage, but in many cases this is not sufficient. The awareness percentage gives no indication of which of the consumer segments that are aware of and use labelling schemes and which do not....... In the spring of 2001 MAPP carried out an extensive consumer study with special emphasis on the Nordic environmentally friendly label 'the swan'. The purpose was to find out how much consumers actually know and use various labelling schemes. 869 households were contacted and asked to fill in a questionnaire....... 664 households returned a completed questionnaire. There were five answering categories for each label in the questionnaire: * have not seen the label before. * I have seen the label before but I do not know the precise contents of the labelling scheme. * I have seen the label before, I do not know...
An Efficient Quantum Somewhat Homomorphic Symmetric Searchable Encryption
Sun, Xiaoqiang; Wang, Ting; Sun, Zhiwei; Wang, Ping; Yu, Jianping; Xie, Weixin
2017-04-01
In 2009, Gentry first introduced an ideal lattices fully homomorphic encryption (FHE) scheme. Later, based on the approximate greatest common divisor problem, learning with errors problem or learning with errors over rings problem, FHE has developed rapidly, along with the low efficiency and computational security. Combined with quantum mechanics, Liang proposed a symmetric quantum somewhat homomorphic encryption (QSHE) scheme based on quantum one-time pad, which is unconditional security. And it was converted to a quantum fully homomorphic encryption scheme, whose evaluation algorithm is based on the secret key. Compared with Liang's QSHE scheme, we propose a more efficient QSHE scheme for classical input states with perfect security, which is used to encrypt the classical message, and the secret key is not required in the evaluation algorithm. Furthermore, an efficient symmetric searchable encryption (SSE) scheme is constructed based on our QSHE scheme. SSE is important in the cloud storage, which allows users to offload search queries to the untrusted cloud. Then the cloud is responsible for returning encrypted files that match search queries (also encrypted), which protects users' privacy.
Symmetric Decomposition of Asymmetric Games.
Tuyls, Karl; Pérolat, Julien; Lanctot, Marc; Ostrovski, Georg; Savani, Rahul; Leibo, Joel Z; Ord, Toby; Graepel, Thore; Legg, Shane
2018-01-17
We introduce new theoretical insights into two-population asymmetric games allowing for an elegant symmetric decomposition into two single population symmetric games. Specifically, we show how an asymmetric bimatrix game (A,B) can be decomposed into its symmetric counterparts by envisioning and investigating the payoff tables (A and B) that constitute the asymmetric game, as two independent, single population, symmetric games. We reveal several surprising formal relationships between an asymmetric two-population game and its symmetric single population counterparts, which facilitate a convenient analysis of the original asymmetric game due to the dimensionality reduction of the decomposition. The main finding reveals that if (x,y) is a Nash equilibrium of an asymmetric game (A,B), this implies that y is a Nash equilibrium of the symmetric counterpart game determined by payoff table A, and x is a Nash equilibrium of the symmetric counterpart game determined by payoff table B. Also the reverse holds and combinations of Nash equilibria of the counterpart games form Nash equilibria of the asymmetric game. We illustrate how these formal relationships aid in identifying and analysing the Nash structure of asymmetric games, by examining the evolutionary dynamics of the simpler counterpart games in several canonical examples.
DEFF Research Database (Denmark)
van Leeuwen, Theo
2013-01-01
This chapter presents a framework for analysing colour schemes based on a parametric approach that includes not only hue, value and saturation, but also purity, transparency, luminosity, luminescence, lustre, modulation and differentiation.......This chapter presents a framework for analysing colour schemes based on a parametric approach that includes not only hue, value and saturation, but also purity, transparency, luminosity, luminescence, lustre, modulation and differentiation....
Conformal Killing Vectors Of Plane Symmetric Four Dimensional Lorentzian Manifolds
Khan, Suhail; Bokhari, Ashfaque H; Khan, Gulzar Ali; Mathematics, Department of; Peshawar, University of; Pakhtoonkhwa, Peshawar Khyber; Pakistan.,; Petroleum, King Fahd University of; Minerals,; 31261, Dhahran; Arabia, Saudi
2015-01-01
In this paper, we investigate conformal Killing's vectors (CKVs) admitted by some plane symmetric spacetimes. Ten conformal Killing's equations and their general forms of CKVs are derived along with their conformal factor. The existence of conformal Killing's symmetry imposes restrictions on the metric functions. The conditions imposing restrictions on these metric functions are obtained as a set of integrability conditions. Considering the cases of time-like and inheriting CKVs, we obtain spacetimes admitting plane conformal symmetry. Integrability conditions are solved completely for some known non-conformally flat and conformally flat classes of plane symmetric spacetimes. A special vacuum plane symmetric spacetime is obtained, and it is shown that for such a metric CKVs are just the homothetic vectors (HVs). Among all the examples considered, there exists only one case with a six dimensional algebra of special CKVs admitting one proper CKV. In all other examples of non-conformally flat metrics, no proper ...
Dynamic Restarting Schemes for Eigenvalue Problems
Energy Technology Data Exchange (ETDEWEB)
Wu, Kesheng; Simon, Horst D.
1999-03-10
In studies of restarted Davidson method, a dynamic thick-restart scheme was found to be excellent in improving the overall effectiveness of the eigen value method. This paper extends the study of the dynamic thick-restart scheme to the Lanczos method for symmetric eigen value problems and systematically explore a range of heuristics and strategies. We conduct a series of numerical tests to determine their relative strength and weakness on a class of electronic structure calculation problems.
Mesotherapy for benign symmetric lipomatosis.
Hasegawa, Toshio; Matsukura, Tomoyuki; Ikeda, Shigaku
2010-04-01
Benign symmetric lipomatosis, also known as Madelung disease, is a rare disorder characterized by fat distribution around the shoulders, arms, and neck in the context of chronic alcoholism. Complete excision of nonencapsulated lipomas is difficult. However, reports describing conservative therapeutic measures for lipomatosis are rare. The authors present the case of a 42-year-old man with a diagnosis of benign symmetric lipomatosis who had multiple, large, symmetrical masses in his neck. Multiple phosphatidylcholine injections in the neck were administered 4 weeks apart, a total of seven times to achieve lipolysis. The patient's lipomatosis improved in response to the injections, and he achieved good cosmetic results. Intralesional injection, termed mesotherapy, using phosphatidylcholine is a potentially effective therapy for benign symmetric lipomatosis that should be reconsidered as a therapeutic option for this disease.
Spherically symmetric perfect fluid solutions
Energy Technology Data Exchange (ETDEWEB)
Hajj-Boutros, J.
1985-04-01
Many exact solutions for the spherically symmetric perfect fluid distribution of matter with shear, acceleration, and expansion are obtained. One of them is expressed in terms of Painleve's third transcendent.
Symmetric Cryptography (Dagstuhl Seminar 16021)
Armknecht, Frederik; Iwata, Tetsu; Nyberg, Kaisa; Preneel, Bart
2016-01-01
From 10.01.2016 to 15.01.2016, the Seminar 16021 in Symmetric Cryptography was held in Schloss Dagstuhl-Leibniz Center for Informatics. It was the fifth in the series of the Dagstuhl seminars "Symmetric Cryptography" held in 2007, 2009, 2012, and 2014. During the seminar, several participants presented their current research, and ongoing work and open problems were discussed. Abstracts of the presentations were given during the seminar. The first section describes the seminar topics and g...
Feedback-Based Collaborative Secrecy Encoding over Binary Symmetric Channels
Amariucai, George
2009-01-01
In this paper we propose a feedback scheme for transmitting secret messages between two legitimate parties, over an eavesdropped communication link. Relative to Wyner's traditional encoding scheme \\cite{wyner1}, our feedback-based encoding often yields larger rate-equivocation regions and achievable secrecy rates. More importantly, by exploiting the channel randomness inherent in the feedback channels, our scheme achieves a strictly positive secrecy rate even when the eavesdropper's channel is less noisy than the legitimate receiver's channel. All channels are modeled as binary and symmetric (BSC). We demonstrate the versatility of our feedback-based encoding method by using it in three different configurations: the stand-alone configuration, the mixed configuration (when it combines with Wyner's scheme \\cite{wyner1}), and the reversed configuration. Depending on the channel conditions, significant improvements over Wyner's secrecy capacity can be observed in all configurations.
On the construction of symmetric nonnegative matrix with prescribed Ritz values
Directory of Open Access Journals (Sweden)
Alimohammad Nazari
2014-09-01
Full Text Available In this paper for a given prescribed Ritz values that satisfy inthe some special conditions, we find a symmetric nonnegativematrix, such that the given set be its Ritz values.
Geometrical Inverse Preconditioning for Symmetric Positive Definite Matrices
Directory of Open Access Journals (Sweden)
Jean-Paul Chehab
2016-07-01
Full Text Available We focus on inverse preconditioners based on minimizing F ( X = 1 − cos ( X A , I , where X A is the preconditioned matrix and A is symmetric and positive definite. We present and analyze gradient-type methods to minimize F ( X on a suitable compact set. For this, we use the geometrical properties of the non-polyhedral cone of symmetric and positive definite matrices, and also the special properties of F ( X on the feasible set. Preliminary and encouraging numerical results are also presented in which dense and sparse approximations are included.
Practical schemes for privacy and security enhanced RFID
Hoepman, J.H.; Joosten, R.
2010-01-01
Proper privacy protection in RFID systems is important. However, many of the schemes known are impractical, either because they use hash functions instead of the more hardware efficient symmetric encryption schemes as a efficient cryptographic primitive, or because they incur a rather costly key
Particle-vortex symmetric liquid
Mulligan, Michael
2016-01-01
We introduce an effective theory with manifest particle-vortex symmetry for disordered thin films undergoing a magnetic field-tuned superconductor-insulator transition. The theory may enable one to access both the critical properties of the strong-disorder limit, which has recently been confirmed [Breznay et al., PNAS 113, 280 (2016)] to exhibit particle-vortex symmetric electrical response, and the metallic phase discovered earlier [Mason and Kapitulnik, Phys. Rev. Lett. 82, 5341 (1999)] in less disordered samples. Within the effective theory, the Cooper-pair and field-induced vortex degrees of freedom are simultaneously incorporated into an electrically-neutral Dirac fermion minimally coupled to an (emergent) Chern-Simons gauge field. A derivation of the theory follows upon mapping the superconductor-insulator transition to the integer quantum Hall plateau transition and the subsequent use of Son's particle-hole symmetric composite Fermi liquid. Remarkably, particle-vortex symmetric response does not requir...
Differential geometry and symmetric spaces
Helgason, Sigurdur
2001-01-01
Sigurdur Helgason's Differential Geometry and Symmetric Spaces was quickly recognized as a remarkable and important book. For many years, it was the standard text both for Riemannian geometry and for the analysis and geometry of symmetric spaces. Several generations of mathematicians relied on it for its clarity and careful attention to detail. Although much has happened in the field since the publication of this book, as demonstrated by Helgason's own three-volume expansion of the original work, this single volume is still an excellent overview of the subjects. For instance, even though there
Symmetric normalisation for intuitionistic logic
DEFF Research Database (Denmark)
Guenot, Nicolas; Straßburger, Lutz
2014-01-01
We present two proof systems for implication-only intuitionistic logic in the calculus of structures. The first is a direct adaptation of the standard sequent calculus to the deep inference setting, and we describe a procedure for cut elimination, similar to the one from the sequent calculus......, but using a non-local rewriting. The second system is the symmetric completion of the first, as normally given in deep inference for logics with a DeMorgan duality: all inference rules have duals, as cut is dual to the identity axiom. We prove a generalisation of cut elimination, that we call symmetric...
On the Moduli Space of non-BPS Attractors for N=2 Symmetric Manifolds
Ferrara, Sergio
2007-01-01
We study the ``flat'' directions of non-BPS extremal black hole attractors for N=2, d=4 supergravities whose vector multiplets' scalar manifold is endowed with homogeneous symmetric special Kahler geometry. The non-BPS attractors with non-vanishing central charge have a moduli space described by real special geometry (and thus related to the d=5 parent theory), whereas the moduli spaces of non-BPS attractors with vanishing central charge are certain Kahler homogeneous symmetric manifolds. The moduli spaces of the non-BPS attractors of the corresponding N=2, d=5 theories are also indicated, and shown to be rank-1 homogeneous symmetric manifolds.
Symmetrical progressive erythro-keratoderma
Directory of Open Access Journals (Sweden)
Sunil Gupta
1999-01-01
Full Text Available A 13-year-old male child had gradually progressive, bilaterall, symmetrical, erythematous hyperkeratotic plaques over knees, elbows, natal cleft, dorsa of hands and feet with palmoplantar keratoderma. High arched palate, fissured tongue and sternal depression (pectus-excavatum were unusual associations.
Vassiliev Invariants from Symmetric Spaces
DEFF Research Database (Denmark)
Biswas, Indranil; Gammelgaard, Niels Leth
We construct a natural framed weight system on chord diagrams from the curvature tensor of any pseudo-Riemannian symmetric space. These weight systems are of Lie algebra type and realized by the action of the holonomy Lie algebra on a tangent space. Among the Lie algebra weight systems, they are ...
Symmetrical Extensions of Dirichlet Operators
Us, A G
1997-01-01
There is constructed and considered the extension of classical Diriclet operator corresponding to uniformly log-concave measure in the space of symmetric differential forms. Sufficient conditions for its essential self-adjointness in one-dimensional case as well as for the same of its "sypersymmetric" part in general situations are given.
Understanding symmetrical components for power system modeling
Das, J C
2017-01-01
This book utilizes symmetrical components for analyzing unbalanced three-phase electrical systems, by applying single-phase analysis tools. The author covers two approaches for studying symmetrical components; the physical approach, avoiding many mathematical matrix algebra equations, and a mathematical approach, using matrix theory. Divided into seven sections, topics include: symmetrical components using matrix methods, fundamental concepts of symmetrical components, symmetrical components –transmission lines and cables, sequence components of rotating equipment and static load, three-phase models of transformers and conductors, unsymmetrical fault calculations, and some limitations of symmetrical components.
On convergence completeness in symmetric spaces | Moshokoa ...
African Journals Online (AJOL)
convergence complete symmetric space. As applications of convergence completeness, we present some fixed point results for self-maps defined on a symmetric space. Keywords: completeness; convergence completeness; fixed points; metric ...
Parity-Time Symmetric Photonics
Zhao, Han
2018-01-17
The establishment of non-Hermitian quantum mechanics (such as parity-time (PT) symmetry) stimulates a paradigmatic shift for studying symmetries of complex potentials. Owing to the convenient manipulation of optical gain and loss in analogy to the complex quantum potentials, photonics provides an ideal platform for visualization of many conceptually striking predictions from the non-Hermitian quantum theory. A rapidly developing field has emerged, namely, PT symmetric photonics, demonstrating intriguing optical phenomena including eigenstate coalescence and spontaneous PT symmetry breaking. The advance of quantum physics, as the feedback, provides photonics with brand-new paradigms to explore the entire complex permittivity plane for novel optical functionalities. Here, we review recent exciting breakthroughs in PT symmetric photonics while systematically presenting their underlying principles guided by non-Hermitian symmetries. The potential device applications for optical communication and computing, bio-chemical sensing, and healthcare are also discussed.
Maximally Symmetric Composite Higgs Models
Csáki, Csaba; Ma, Teng; Shu, Jing
2017-09-01
Maximal symmetry is a novel tool for composite pseudo Goldstone boson Higgs models: it is a remnant of an enhanced global symmetry of the composite fermion sector involving a twisting with the Higgs field. Maximal symmetry has far-reaching consequences: it ensures that the Higgs potential is finite and fully calculable, and also minimizes the tuning. We present a detailed analysis of the maximally symmetric S O (5 )/S O (4 ) model and comment on its observational consequences.
Symmetric two-coordinate photodiode
Directory of Open Access Journals (Sweden)
Dobrovolskiy Yu. G.
2008-12-01
Full Text Available The two-coordinate photodiode is developed and explored on the longitudinal photoeffect, which allows to get the coordinate descriptions symmetric on the steepness and longitudinal resistance great exactness. It was shown, that the best type of the coordinate description is observed in the case of scanning by the optical probe on the central part of the photosensitive element. The ways of improvement of steepness and linear of its coordinate description were analyzed.
Additive operator-difference schemes splitting schemes
Vabishchevich, Petr N
2013-01-01
Applied mathematical modeling isconcerned with solving unsteady problems. This bookshows how toconstruct additive difference schemes to solve approximately unsteady multi-dimensional problems for PDEs. Two classes of schemes are highlighted: methods of splitting with respect to spatial variables (alternating direction methods) and schemes of splitting into physical processes. Also regionally additive schemes (domain decomposition methods)and unconditionally stable additive schemes of multi-component splitting are considered for evolutionary equations of first and second order as well as for sy
Dispersion in a bent-solenoid channel with symmetric focusing
Energy Technology Data Exchange (ETDEWEB)
Wang, Chun-xi [Argonne National Lab. (ANL), Argonne, IL (United States)
2001-08-21
Longitudinal ionization cooling of a muon beam is essential for muon colliders and will be useful for neutrino factories. Bent-solenoid channels with symmetric focusing has been considered for beam focusing and for generating the required dispersion in the ``emittance exchange'' scheme of longitudinal cooling. In this paper, we derive the Hamiltonian that governs the linear beam dynamics of a bent-solenoid channel, solve the single-particle dynamics, and give equations for determining the lattice functions, in particular, the dispersion functions.
Geometries and interpolations for symmetric positive definite matrices
DEFF Research Database (Denmark)
Feragen, Aasa; Fuster, Andrea
2017-01-01
In this survey we review classical and recently proposed Riemannian metrics and interpolation schemes on the space of symmetric positive definite (SPD) matrices. We perform simulations that illustrate the problem of tensor fattening not only in the usually avoided Frobenius metric, but also...... the visualization of scale and shape variation in tensorial data. With the paper, we will release a software package with Matlab scripts for computing the interpolations and statistics used for the experiments in the paper (Code is available at https://sites.google.com/site/aasaferagen/home/software)....
Immanant Conversion on Symmetric Matrices
Directory of Open Access Journals (Sweden)
Purificação Coelho M.
2014-01-01
Full Text Available Letr Σn(C denote the space of all n χ n symmetric matrices over the complex field C. The main objective of this paper is to prove that the maps Φ : Σn(C -> Σn (C satisfying for any fixed irre- ducible characters X, X' -SC the condition dx(A +aB = dχ·(Φ(Α + αΦ(Β for all matrices A,В ε Σ„(С and all scalars a ε C are automatically linear and bijective. As a corollary of the above result we characterize all such maps Φ acting on ΣИ(С.
Scheme Program Documentation Tools
DEFF Research Database (Denmark)
Nørmark, Kurt
2004-01-01
This paper describes and discusses two different Scheme documentation tools. The first is SchemeDoc, which is intended for documentation of the interfaces of Scheme libraries (APIs). The second is the Scheme Elucidator, which is for internal documentation of Scheme programs. Although the tools...
Symmetric large momentum transfer for atom interferometry with BECs
Abend, Sven; Gebbe, Martina; Gersemann, Matthias; Rasel, Ernst M.; Quantus Collaboration
2017-04-01
We develop and demonstrate a novel scheme for a symmetric large momentum transfer beam splitter for interferometry with Bose-Einstein condensates. Large momentum transfer beam splitters are a key technique to enhance the scaling factor and sensitivity of an atom interferometer and to create largely delocalized superposition states. To realize the beam splitter, double Bragg diffraction is used to create a superposition of two symmetric momentum states. Afterwards both momentum states are loaded into a retro-reflected optical lattice and accelerated by Bloch oscillations on opposite directions, keeping the initial symmetry. The favorable scaling behavior of this symmetric acceleration, allows to transfer more than 1000 ℏk of total differential splitting in a single acceleration sequence of 6 ms duration while we still maintain a fraction of approx. 25% of the initial atom number. As a proof of the coherence of this beam splitter, contrast in a closed Mach-Zehnder atom interferometer has been observed with up to 208 ℏk of momentum separation, which equals a differential wave-packet velocity of approx. 1.1 m/s for 87Rb. The presented work is supported by the CRC 1128 geo-Q and the DLR with funds provided by the Federal Ministry of Economic Affairs and Energy (BMWi) due to an enactment of the German Bundestag under Grant No. DLR 50WM1552-1557 (QUANTUS-IV-Fallturm).
Classification of symmetric toroidal orbifolds
Energy Technology Data Exchange (ETDEWEB)
Fischer, Maximilian; Ratz, Michael; Torrado, Jesus [Technische Univ. Muenchen, Garching (Germany). Physik-Department; Vaudrevange, Patrick K.S. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)
2012-09-15
We provide a complete classification of six-dimensional symmetric toroidal orbifolds which yield N{>=}1 supersymmetry in 4D for the heterotic string. Our strategy is based on a classification of crystallographic space groups in six dimensions. We find in total 520 inequivalent toroidal orbifolds, 162 of them with Abelian point groups such as Z{sub 3}, Z{sub 4}, Z{sub 6}-I etc. and 358 with non-Abelian point groups such as S{sub 3}, D{sub 4}, A{sub 4} etc. We also briefly explore the properties of some orbifolds with Abelian point groups and N=1, i.e. specify the Hodge numbers and comment on the possible mechanisms (local or non-local) of gauge symmetry breaking.
Symmetric functions and Hall polynomials
MacDonald, Ian Grant
1998-01-01
This reissued classic text is the acclaimed second edition of Professor Ian Macdonald's groundbreaking monograph on symmetric functions and Hall polynomials. The first edition was published in 1979, before being significantly expanded into the present edition in 1995. This text is widely regarded as the best source of information on Hall polynomials and what have come to be known as Macdonald polynomials, central to a number of key developments in mathematics and mathematical physics in the 21st century Macdonald polynomials gave rise to the subject of double affine Hecke algebras (or Cherednik algebras) important in representation theory. String theorists use Macdonald polynomials to attack the so-called AGT conjectures. Macdonald polynomials have been recently used to construct knot invariants. They are also a central tool for a theory of integrable stochastic models that have found a number of applications in probability, such as random matrices, directed polymers in random media, driven lattice gases, and...
Chaaban, Anas
2016-03-01
The symmetric K-user interference channel is studied with the goal of characterizing its capacity region in the strong interference regime within a constant gap. The achievable rate region of a scheme combining rate-splitting at the transmitters and interference alignment and successive decoding/computation at the receivers is derived. Next it is shown that this scheme achieves the so-called greedy-max corner points of the capacity region within a constant gap. By combining this result with previous results by Ordentlich et al. on the sum-capacity of the symmetric interference channel, a constant gap characterization of the capacity region for the strong interference regime is obtained. This leads to the first approximate characterization of the capacity region of the symmetric K-user IC. Furthermore, a new scheme that achieves the sum-capacity of the channel in the strong interference regime within a constant gap is also proposed, and the corresponding gap is calculated. The advantage of the new scheme is that it leads to a characterization within a constant gap without leaving an outage set contrary to the scheme by Ordentlich et al..
Spherically symmetric conformal gravity and "gravitational bubbles"
Berezin, V A; Eroshenko, Yu N
2016-01-01
The general structure of the spherically symmetric solutions in the Weyl conformal gravity is described. The corresponding Bach equation are derived for the special type of metrics, which can be considered as the representative of the general class. The complete set of the pure vacuum solutions is found. It consists of two classes. The first one contains the solutions with constant two-dimensional curvature scalar of our specific metrics, and the representatives are the famous Robertson-Walker metrics. One of them we called the "gravitational bubbles", which is compact and with zero Weyl tensor. The second class is more general, with varying curvature scalar. We found its representative as the one-parameter family. It appears that it can be conformally covered by the thee-parameter Mannheim-Kazanas solution. We also investigated the general structure of the energy-momentum tensor in the spherical conformal gravity and constructed the vectorial equation that reveals clearly the same features of non-vacuum solu...
On symplectic and symmetric ARKN methods
Shi, Wei; Wu, Xinyuan
2012-06-01
Symplecticness and symmetry are favorable properties for solving Hamiltonian systems. For the oscillatory second-order initial value problems of the form q+ωq=f(q,q), adapted Runge-Kutta-Nyström methods (ARKN methods, in short notation) were investigated by several authors. In a wide range of physical applications from molecular dynamics to nonlinear wave propagation, an important class of the problems is Hamiltonian systems for which symplectic methods should be preferred. Hence it is quite natural to raise a question of the symplecticness for ARKN methods. In this paper we investigate the symplecticness conditions of ARKN methods for separable Hamiltonian systems. We conclude that there exist only one-stage explicit symplectic ARKN (SARKN, in short notation) methods under the symplecticness conditions of ARKN methods. The SARKN methods have a special form and the algebraic order cannot exceed 2. We also point out that no ARKN method can be symmetric. An explicit SARKN method of order two is proposed with the analysis of phase and stability properties. The numerical results accompanied show good performance for the new explicit symplectic algorithm in comparison with the popular symplectic methods in the scientific literature.
Symmetric Key Services Markup Language (SKSML)
Noor, Arshad
Symmetric Key Services Markup Language (SKSML) is the eXtensible Markup Language (XML) being standardized by the OASIS Enterprise Key Management Infrastructure Technical Committee for requesting and receiving symmetric encryption cryptographic keys within a Symmetric Key Management System (SKMS). This protocol is designed to be used between clients and servers within an Enterprise Key Management Infrastructure (EKMI) to secure data, independent of the application and platform. Building on many security standards such as XML Signature, XML Encryption, Web Services Security and PKI, SKSML provides standards-based capability to allow any application to use symmetric encryption keys, while maintaining centralized control. This article describes the SKSML protocol and its capabilities.
Novel addressing scheme for passive antiferroelectric liquid crystal displays
Quintana, Xabier; Castillo, P. L.; Oton, Jose; Bennis, N.; Lara, A.; Urruchi, V.; Dabrowski, Roman S.
2004-09-01
In this work, the use of antiferroelectric liquid crystals for high-end passive displays has been explored. Antiferroelectric gray levels arise from a double symmetric hysteresis loop that can be stabilized by a constant holding voltage. This driving scheme is passive multiplexing compatible, but limitations appear when the multiplexing rate increases. We have developed new waveforms and driving schemes for high multiplexing level at video rate. The problem of accumulated voltage on bias level arising from data voltages is tackled as well.
Generalized geometry and non-symmetric gravity
Jurco, Branislav; Khoo, Fech Scen; Schupp, Peter; Vysoky, Jan
2015-01-01
Generalized geometry provides the framework for a systematic approach to non-symmetric metric gravity theory and naturally leads to an Einstein-Kalb-Ramond gravity theory with totally anti-symmetric contortion. The approach is related to the study of the low-energy effective closed string gravity actions.
Equivariant embeddings of Hermitian symmetric spaces
Indian Academy of Sciences (India)
E-mail: Laurent.Clozel@math.u-psud.fr. MS received 28 November 2006; revised 3 April 2007. Abstract. We prove that equivariant, holomorphic embeddings of Hermitian symmetric spaces are totally geodesic (when the image is not of exceptional type). Keywords. Complex variables; metric geometry (symmetric spaces). 1.
On completeness in symmetric spaces | Moshokoa | Quaestiones ...
African Journals Online (AJOL)
In the literature completeness for symmetric spaces is done through the classical Cauchy criterion for metric spaces. However, unlike the situation in metric spaces a convergent sequence in a symmetric space is not necessarily a Cauchy sequence. In the paper we introduce a notion of convergence completeness for ...
An accurate scheme by block method for third order ordinary ...
African Journals Online (AJOL)
A block linear multistep method for solving special third order initial value problems of ordinary differential equations is presented in this paper. The approach of collocation approximation is adopted in the derivation of the scheme and then the scheme is applied as simultaneous integrator to special third order initial value ...
Spherically symmetric charged compact stars
Energy Technology Data Exchange (ETDEWEB)
Maurya, S.K. [University of Nizwa, Department of Mathematical and Physical Sciences, College of Arts and Science, Nizwa (Oman); Gupta, Y.K. [Jaypee Institute of Information Technology University, Department of Mathematics, Noida, Uttar Pradesh (India); Ray, Saibal [Government College of Engineering and Ceramic Technology, Department of Physics, Kolkata, West Bengal (India); Chowdhury, Sourav Roy [Seth Anandaram Jaipuria College, Department of Physics, Kolkata, West Bengal (India)
2015-08-15
In this article we consider the static spherically symmetric metric of embedding class 1. When solving the Einstein-Maxwell field equations we take into account the presence of ordinary baryonic matter together with the electric charge. Specific new charged stellar models are obtained where the solutions are entirely dependent on the electromagnetic field, such that the physical parameters, like density, pressure etc. do vanish for the vanishing charge. We systematically analyze altogether the three sets of Solutions I, II, and III of the stellar models for a suitable functional relation of ν(r). However, it is observed that only the Solution I provides a physically valid and well-behaved situation, whereas the Solutions II and III are not well behaved and hence not included in the study. Thereafter it is exclusively shown that the Solution I can pass through several standard physical tests performed by us. To validate the solution set presented here a comparison has also been made with that of the compact stars, like RX J 1856 - 37, Her X - 1, PSR 1937+21, PSRJ 1614-2230, and PSRJ 0348+0432, and we have shown the feasibility of the models. (orig.)
Complex {PT}-symmetric extensions of the nonlinear ultra-short light pulse model
Yan, Zhenya
2012-11-01
The short pulse equation u_{xt}=u+\\frac{1}{2}(u^2u_x)_x is PT symmetric, which arises in nonlinear optics for the ultra-short pulse case. We present a family of new complex PT-symmetric extensions of the short pulse equation, i[(iu_x)^{\\sigma }]_t=au+bu^m+ic[u^n(iu_x)^{\\epsilon }]_x \\,\\, (\\sigma ,\\, \\epsilon ,\\,a,\\,b,\\,c,\\,m,\\,n \\in {R}), based on the complex PT-symmetric extension principle. Some properties of these equations with some chosen parameters are studied including the Hamiltonian structures and exact solutions such as solitary wave solutions, doubly periodic wave solutions and compacton solutions. Our results may be useful to understand complex PT-symmetric nonlinear physical models. This article is part of a special issue of Journal of Physics A: Mathematical and Theoretical devoted to ‘Quantum physics with non-Hermitian operators’.
PERIODIC-ORBITS IN K-SYMMETRICAL DYNAMICAL-SYSTEMS
BRANDS, H; LAMB, JSW; HOVEIJN, [No Value
1995-01-01
A map L is called k-symmetric if its kth iterate L(k) possesses more symmetry than L, for some value of k. In k-symmetric systems, there exists a notion of k-symmetric orbits. This paper deals with k-symmetric periodic orbits. We derive a relation between orbits that are k-symmetric with respect to
A symmetric positive definite formulation for monolithic fluid structure interaction
Robinson-Mosher, Avi
2011-02-01
In this paper we consider a strongly coupled (monolithic) fluid structure interaction framework for incompressible flow, as opposed to a loosely coupled (partitioned) method. This requires solving a single linear system that combines the unknown velocities of the structure with the unknown pressures of the fluid. In our previous work, we were able to obtain a symmetric formulation of this coupled system; however, it was also indefinite, making it more difficult to solve. In fact in practice there have been cases where we have been unable to invert the system. In this paper we take a novel approach that consists of factoring the damping matrix of deformable structures and show that this can be used to obtain a symmetric positive definite system, at least to the extent that the uncoupled systems were symmetric positive definite. We use a traditional MAC grid discretization of the fluid and a fully Lagrangian discretization of the structures for the sake of exposition, noting that our procedure can be generalized to other scenarios. For the special case of rigid bodies, where there are no internal damping forces, we exactly recover the system of Batty et al. (2007) [4]. © 2010 Elsevier Inc.
Random matrix theory and symmetric spaces
Energy Technology Data Exchange (ETDEWEB)
Caselle, M.; Magnea, U
2004-05-01
In this review we discuss the relationship between random matrix theories and symmetric spaces. We show that the integration manifolds of random matrix theories, the eigenvalue distribution, and the Dyson and boundary indices characterizing the ensembles are in strict correspondence with symmetric spaces and the intrinsic characteristics of their restricted root lattices. Several important results can be obtained from this identification. In particular the Cartan classification of triplets of symmetric spaces with positive, zero and negative curvature gives rise to a new classification of random matrix ensembles. The review is organized into two main parts. In Part I the theory of symmetric spaces is reviewed with particular emphasis on the ideas relevant for appreciating the correspondence with random matrix theories. In Part II we discuss various applications of symmetric spaces to random matrix theories and in particular the new classification of disordered systems derived from the classification of symmetric spaces. We also review how the mapping from integrable Calogero-Sutherland models to symmetric spaces can be used in the theory of random matrices, with particular consequences for quantum transport problems. We conclude indicating some interesting new directions of research based on these identifications.
On large N limit of symmetric traceless tensor models
Klebanov, Igor R.; Tarnopolsky, Grigory
2017-10-01
For some theories where the degrees of freedom are tensors of rank 3 or higher, there exist solvable large N limits dominated by the melonic diagrams. Simple examples are provided by models containing one rank 3 tensor in the tri-fundamental representation of the O( N)3 symmetry group. When the quartic interaction is assumed to have a special tetrahedral index structure, the coupling constant g must be scaled as N -3/2 in the melonic large N limit. In this paper we consider the combinatorics of a large N theory of one fully symmetric and traceless rank-3 tensor with the tetrahedral quartic interaction; this model has a single O( N ) symmetry group. We explicitly calculate all the vacuum diagrams up to order g 8, as well as some diagrams of higher order, and find that in the large N limit where g 2 N 3 is held fixed only the melonic diagrams survive. While some non-melonic diagrams are enhanced in the O( N ) symmetric theory compared to the O( N )3 one, we have not found any diagrams where this enhancement is strong enough to make them comparable with the melonic ones. Motivated by these results, we conjecture that the model of a real rank-3 symmetric traceless tensor possesses a smooth large N limit where g 2 N 3 is held fixed and all the contributing diagrams are melonic. A feature of the symmetric traceless tensor models is that some vacuum diagrams containing odd numbers of vertices are suppressed only by N -1/2 relative to the melonic graphs.
A class of symmetric controlled quantum operations
Energy Technology Data Exchange (ETDEWEB)
Vaccaro, John A.; Steuernagel, O.; Huelga, S.F. [Division of Physics and Astronomy, Department of Physical Sciences, University of Hertfordshire, Hatfield (United Kingdom)
2001-09-07
Certain quantum gates, such as the controlled-NOT gate, are symmetric in terms of the operation of the control system upon the target system and vice versa. However, no operational criteria yet exist for establishing whether or not a given quantum gate is symmetrical in this sense. We consider a restricted, yet broad, class of two-party controlled gate operations for which the gate transforms a reference state of the target into one of an orthogonal set of states. We show that for this class of gates it is possible to establish a simple necessary and sufficient condition for the gate operation to be symmetric. (author)
Energy decomposition scheme based on the generalized Kohn-Sham scheme.
Su, Peifeng; Jiang, Zhen; Chen, Zuochang; Wu, Wei
2014-04-03
In this paper, a new energy decomposition analysis scheme based on the generalized Kohn-Sham (GKS) and the localized molecular orbital energy decomposition analysis (LMO-EDA) scheme, named GKS-EDA, is proposed. The GKS-EDA scheme has a wide range of DFT functional adaptability compared to LMO-EDA. In the GKS-EDA scheme, the exchange, repulsion, and polarization terms are determined by DFT orbitals; the correlation term is defined as the difference of the GKS correlation energy from monomers to supermolecule. Using the new definition, the GKS-EDA scheme avoids the error of LMO-EDA which comes from the separated treatment of EX and EC functionals. The scheme can perform analysis both in the gas and in the condensed phases with most of the popular DFT functionals, including LDA, GGA, meta-GGA, hybrid GGA/meta-GGA, double hybrid, range-separated (long-range correction), and dispersion correction. By the GKS-EDA scheme, the DFT functionals assessment for hydrogen bonding, vdW interaction, symmetric radical cation, charge-transfer, and metal-ligand interaction is performed.
Cambridge community Optometry Glaucoma Scheme.
Keenan, Jonathan; Shahid, Humma; Bourne, Rupert R; White, Andrew J; Martin, Keith R
2015-04-01
With a higher life expectancy, there is an increased demand for hospital glaucoma services in the United Kingdom. The Cambridge community Optometry Glaucoma Scheme (COGS) was initiated in 2010, where new referrals for suspected glaucoma are evaluated by community optometrists with a special interest in glaucoma, with virtual electronic review and validation by a consultant ophthalmologist with special interest in glaucoma. 1733 patients were evaluated by this scheme between 2010 and 2013. Clinical assessment is performed by the optometrist at a remote site. Goldmann applanation tonometry, pachymetry, monoscopic colour optic disc photographs and automated Humphrey visual field testing are performed. A clinical decision is made as to whether a patient has glaucoma or is a suspect, and referred on or discharged as a false positive referral. The clinical findings, optic disc photographs and visual field test results are transmitted electronically for virtual review by a consultant ophthalmologist. The number of false positive referrals from initial referral into the scheme. Of the patients, 46.6% were discharged at assessment and a further 5.7% were discharged following virtual review. Of the patients initially discharged, 2.8% were recalled following virtual review. Following assessment at the hospital, a further 10.5% were discharged after a single visit. The COGS community-based glaucoma screening programme is a safe and effective way of evaluating glaucoma referrals in the community and reducing false-positive referrals for glaucoma into the hospital system. © 2014 Royal Australian and New Zealand College of Ophthalmologists.
Topics and Research Directions for Symmetric Cryptography
Biryukov, Alex; Daemen, Joan; Lucks, Stefan; Vaudenay, Serge
2017-01-01
This is a summary of the open discussion on future research topics for symmetric cryptography chaired by Stefan Lucks. During this session participants were suggesting topics of potential future interest.
Martingale Rosenthal inequalities in symmetric spaces
Energy Technology Data Exchange (ETDEWEB)
Astashkin, S V [Samara State University, Samara (Russian Federation)
2014-12-31
We establish inequalities similar to the classical Rosenthal inequalities for sequences of martingale differences in general symmetric spaces; a central role is played here by the predictable quadratic characteristic of a martingale. Bibliography: 26 titles.
Spherically symmetric inhomogeneous dust collapse in higher ...
Indian Academy of Sciences (India)
We consider a collapsing spherically symmetric inhomogeneous dust cloud in higher dimensional space-time. We show that the central singularity of collapse can be a strong curvature or a weak curvature naked singularity depending on the initial density distribution.
Multiple Symmetric Lipomatosis: A Diagnostic Dilemma
Directory of Open Access Journals (Sweden)
Mladen Mimica
2013-01-01
Full Text Available Introduction. Multiple symmetric lipomatosis, or Madelung's disease, is a rare condition which is characterized with large symmetrical accumulation of noncapsulated fat tissue in upper arms, neck, and shoulder areas. The disease etiology is unknown, with the highest incidence in the Mediterranean region. Case Presentation. Here, we present the case of Madelung's disease with symmetric fat distribution throughout the neck and history of alcoholism. The patient was treated from several diseases associated with alcoholism and hospitalized several times, but the diagnosis of Madelung's disease was omitted. The thyroid gland disease was excluded, while enlargement of the neck adipose tissue was attributed to obesity. Conclusions. This study points out possible diagnostic mistakes when a physician is not aware of a differentiation diagnosis of symmetrically enlarged neck masses, especially in geographic regions with high incidence of this disease.
Resistor Networks based on Symmetrical Polytopes
National Research Council Canada - National Science Library
Moody, Jeremy; Aravind, P.K
2015-01-01
This paper shows how a method developed by Van Steenwijk can be generalized to calculate the resistance between any two vertices of a symmetrical polytope all of whose edges are identical resistors...
Analytical results for non-Hermitian parity–time-symmetric and ...
Indian Academy of Sciences (India)
Abstract. We investigate both the non-Hermitian parity–time-(PT-)symmetric and Hermitian asymmetric volcano potentials, and present the analytical solution in terms of the confluent Heun function. Under certain special conditions, the confluent Heun function can be terminated as a polynomial, thereby leading to certain ...
Morse potential, symmetric Morse potential and bracketed bound-state energies
Czech Academy of Sciences Publication Activity Database
Znojil, Miloslav
2016-01-01
Roč. 31, č. 14 (2016), s. 1650088 ISSN 0217-7323 R&D Projects: GA ČR GA16-22945S Institutional support: RVO:61389005 Keywords : quantum bound states * special functions * Morse potential * symmetrized Morse potential * upper and lower energy estimates * computer-assisted symbolic manipulations Subject RIV: BE - Theoretical Physics Impact factor: 1.165, year: 2016
Analytical results for non-Hermitian parity–time-symmetric and ...
Indian Academy of Sciences (India)
We investigate both the non-Hermitian parity–time-(PT-)symmetric and Hermitianasymmetric volcano potentials, and present the analytical solution in terms of the confluent Heun function. Under certain special conditions, the confluent Heun function can be terminated as a polynomial, thereby leading to certain exact ...
Symmetric states: Their nonlocality and entanglement
Energy Technology Data Exchange (ETDEWEB)
Wang, Zizhu; Markham, Damian [CNRS LTCI, Département Informatique et Réseaux, Telecom ParisTech, 23 avenue d' Italie, CS 51327, 75214 Paris CEDEX 13 (France)
2014-12-04
The nonlocality of permutation symmetric states of qubits is shown via an extension of the Hardy paradox and the extension of the associated inequality. This is achieved by using the Majorana representation, which is also a powerful tool in the study of entanglement properties of symmetric states. Through the Majorana representation, different nonlocal properties can be linked to different entanglement properties of a state, which is useful in determining the usefulness of different states in different quantum information processing tasks.
Finite-volume scheme for anisotropic diffusion
Energy Technology Data Exchange (ETDEWEB)
Es, Bram van, E-mail: bramiozo@gmail.com [Centrum Wiskunde & Informatica, P.O. Box 94079, 1090GB Amsterdam (Netherlands); FOM Institute DIFFER, Dutch Institute for Fundamental Energy Research, The Netherlands" 1 (Netherlands); Koren, Barry [Eindhoven University of Technology (Netherlands); Blank, Hugo J. de [FOM Institute DIFFER, Dutch Institute for Fundamental Energy Research, The Netherlands" 1 (Netherlands)
2016-02-01
In this paper, we apply a special finite-volume scheme, limited to smooth temperature distributions and Cartesian grids, to test the importance of connectivity of the finite volumes. The area of application is nuclear fusion plasma with field line aligned temperature gradients and extreme anisotropy. We apply the scheme to the anisotropic heat-conduction equation, and compare its results with those of existing finite-volume schemes for anisotropic diffusion. Also, we introduce a general model adaptation of the steady diffusion equation for extremely anisotropic diffusion problems with closed field lines.
Graph state-based quantum authentication scheme
Liao, Longxia; Peng, Xiaoqi; Shi, Jinjing; Guo, Ying
2017-04-01
Inspired by the special properties of the graph state, a quantum authentication scheme is proposed in this paper, which is implemented with the utilization of the graph state. Two entities, a reliable party, Trent, as a verifier and Alice as prover are included. Trent is responsible for registering Alice in the beginning and confirming Alice in the end. The proposed scheme is simple in structure and convenient to realize in the realistic physical system due to the use of the graph state in a one-way quantum channel. In addition, the security of the scheme is extensively analyzed and accordingly can resist the general individual attack strategies.
Simple and High-Accurate Schemes for Hyperbolic Conservation Laws
Directory of Open Access Journals (Sweden)
Renzhong Feng
2014-01-01
Full Text Available The paper constructs a class of simple high-accurate schemes (SHA schemes with third order approximation accuracy in both space and time to solve linear hyperbolic equations, using linear data reconstruction and Lax-Wendroff scheme. The schemes can be made even fourth order accurate with special choice of parameter. In order to avoid spurious oscillations in the vicinity of strong gradients, we make the SHA schemes total variation diminishing ones (TVD schemes for short by setting flux limiter in their numerical fluxes and then extend these schemes to solve nonlinear Burgers’ equation and Euler equations. The numerical examples show that these schemes give high order of accuracy and high resolution results. The advantages of these schemes are their simplicity and high order of accuracy.
Hardware Realization of Chaos-based Symmetric Video Encryption
Ibrahim, Mohamad A.
2013-05-01
This thesis reports original work on hardware realization of symmetric video encryption using chaos-based continuous systems as pseudo-random number generators. The thesis also presents some of the serious degradations caused by digitally implementing chaotic systems. Subsequently, some techniques to eliminate such defects, including the ultimately adopted scheme are listed and explained in detail. Moreover, the thesis describes original work on the design of an encryption system to encrypt MPEG-2 video streams. Information about the MPEG-2 standard that fits this design context is presented. Then, the security of the proposed system is exhaustively analyzed and the performance is compared with other reported systems, showing superiority in performance and security. The thesis focuses more on the hardware and the circuit aspect of the system’s design. The system is realized on Xilinx Vetrix-4 FPGA with hardware parameters and throughput performance surpassing conventional encryption systems.
Conformable heat equation on a radial symmetric plate
Directory of Open Access Journals (Sweden)
Avci Derya
2017-01-01
Full Text Available The conformable heat equation is defined in terms of a local and limit-based definition called conformable derivative which provides some basic properties of integer order derivative such that conventional fractional derivatives lose some of them due to their non-local structures. In this paper, we aim to find the fundamental solution of a conformable heat equation acting on a radial symmetric plate. Moreover, we give a comparison between the new conformable and the existing Grunwald-Letnikov solutions of heat equation. The computational results show that conformable formulation is quite successful to show the sub-behaviors of heat process. In addition, conformable solution can be obtained by a analytical method without the need of a numerical scheme and any restrictions on the problem formulation. This is surely a significant advantageous compared to the Grunwald-Letnikov solution.
Thermoacoustic focusing lens by symmetric Airy beams with phase manipulations
Liu, Chen; Xia, Jian-Ping; Sun, Hong-Xiang; Yuan, Shou-Qi
2017-12-01
We report the realization of broadband acoustic focusing lenses based on two symmetric thermoacoustic phased arrays of Airy beams, in which the units of thermoacoustic phase control are designed by employing air with different temperatures surrounded by rigid insulated boundaries and thermal insulation films. The phase delays of the transmitted and reflected units could cover a whole 2π interval, which arises from the change of the sound velocity of air induced by the variation of the temperature. Based on the units of phase control, we design the transmitted and reflected acoustic focusing lenses with two symmetric Airy beams, and verify the high self-healing focusing characteristic and the feasibility of the thermal insulation films. Besides, the influences of the bending angle of the Airy beam on the focusing performance are discussed in detail. The proposed acoustic lens has advantages of broad bandwidth (about 4.8 kHz), high focusing performance, self-healing feature, and simple structure, which enable it to provide more schemes for acoustic focusing. It has excellent potential applications in acoustic devices.
Love, Patrick G.; Guthrie, Victoria L.
1999-01-01
Summarizes William Perry's intellectual scheme and places it in the context of the 1990's. Perry's scheme of cognitive development, though more than thirty years old, is still being used by practitioners today to enhance practice in and out of the classroom. It laid a foundation for new research to extend, challenge, and build onto the scheme.…
Generation of symmetric Dicke states of remote qubits with linear optics.
Thiel, C; von Zanthier, J; Bastin, T; Solano, E; Agarwal, G S
2007-11-09
We propose a method for generating all symmetric Dicke states, either in the long-lived internal levels of N massive particles or in the polarization degrees of freedom of photonic qubits, using linear optical tools only. By means of a suitable multiphoton detection technique, erasing Welcher-Weg information, our proposed scheme allows the generation and measurement of an important class of entangled multiqubit states.
The limiting form of symmetric instability in geophysical flows
Griffiths, Stephen
2017-04-01
The stability of parallel flow with vertical shear, density stratification and background rotation is of fundamental importance in geophysical fluid dynamics. For a flow with vertical shear Uz and buoyancy frequency N, the dominant instability is typically a symmetric instability (sometimes known as slantwise convection) when 1/4 Uz2. Symmetric instability, which in its simplest form has no along-stream variations, is known to be active in both the troposphere and upper ocean. The corresponding (symmetric) inviscid linear stability problem has been well studied for the case of constant Uz and N, and has some interesting mathematical properties (e.g., non-separable governing PDE, an absence of normal mode solutions in rectangular domains). Here, for the first time, a general theory of symmetric instability is given when Ri varies smoothly with height, thinking of the more realistic case where an unstable layer with Ri 1. The mathematical theory is developed for horizontally periodic disturbances to a basic state with arbitrary smooth N(z), but constant Uz. An asymptotic analysis is used to derive expressions for the most unstable mode, which occurs in the limit of large cross-isentropic wavenumber and takes the form of solutions trapped within the unstable layer; the same result is derived using an interesting generalised parcel dynamics argument, which explicitly shows how the trapping is linked to vertical variations of the potential vorticity. A separate asymptotic analysis is given for the small wavenumber limit, where only one such trapped mode may exist, as expected from the spectral theory of the Schrödinger equation. These two limiting results are shown to be consistent with an exact solution of the linear stability problem that can be obtained for a special choice of N(z). The asymptotic analysis can be extended to allow for weak diffusion at arbitrary Prandtl number, yielding an explicit diffusive scale selection at large wavenumber. Numerical simulations
Analytical Study on Propagation Dynamics of Optical Beam in Parity-Time Symmetric Optical Couplers
Zhou, Zheng; Zhu, Bo; Zhang, Li-Juan
2015-04-01
We present exact analytical solutions to parity-time (PT) symmetric optical system describing light transport in PT-symmetric optical couplers. We show that light intensity oscillates periodically between two waveguides for unbroken PT-symmetric phase, whereas light always leaves the system from the waveguide experiencing gain when light is initially input at either waveguide experiencing gain or waveguide experiencing loss for broken PT-symmetric phase. These analytical results agree with the recent experimental observation reported by Rüter et al. [Nat. Phys. 6 (2010) 192]. Besides, we present a scheme for manipulating PT symmetry by applying a periodic modulation. Our results provide an efficient way to control light propagation in periodically modulated PT-symmetric system by tuning the modulation amplitude and frequency. Supported by the National Natural Science Foundation of China under Grant No. 11465008, the Hunan Provincial Natural Science Foundation under Grant Nos. 2015JJ4020 and 2015JJ2114, the Scientific Research Fund of Hunan Provincial Education Department under Grant No. 14A118
Adaptive Optics Metrics & QC Scheme
Girard, Julien H.
2017-09-01
"There are many Adaptive Optics (AO) fed instruments on Paranal and more to come. To monitor their performances and assess the quality of the scientific data, we have developed a scheme and a set of tools and metrics adapted to each flavour of AO and each data product. Our decisions to repeat observations or not depends heavily on this immediate quality control "zero" (QC0). Atmospheric parameters monitoring can also help predict performances . At the end of the chain, the user must be able to find the data that correspond to his/her needs. In Particular, we address the special case of SPHERE."
Improved synthesis of C-2-symmetrical pyridinediols and synthesis of C-s-symmetrical pyridinediols
Koning, B; Hulst, R; Stroetinga, R; Kellogg, RM
Base-induced reaction of 2,6-dimethylpyridine (2,6-lutidine) (1) with two equivalents of various ketones has been reported to provide C-2-symmetrical pyridine diols 3. Closer examination reveals that competitive di-addition to a single methyl group can occur providing C-s-symmetrical pyridine diols
Chiral light by symmetric optical antennas
Mekonnen, Addis; Zubritskaya, Irina; Jönsson, Gustav Edman; Dmitriev, Alexandre
2014-01-01
Chirality is at the origin of life and is ubiquitous in nature. An object is deemed chiral if it is non-superimposable with its own mirror image. This relates to how circularly polarized light interacts with such object, a circular dichroism, the differential absorption of right and left circularly polarized light. According to the common understanding in biology, chemistry and physics, the circular dichroism results from an internal chiral structure or external symmetry breaking by illumination. We show that circular dichroism is possible with simple symmetric optical nanoantennas at symmetric illumination. We experimentally and theoretically demonstrate that two electromagnetic dipole-like modes with a phase lag, in principle, suffice to produce circular dichroism in achiral structure. Examples of the latter are all visible spectrum optical nanoantennas, symmetric nanoellipses and nanodimers. The simplicity and generality of this finding reveal a whole new significance of the electromagnetic design at a nan...
Revisiting the optical $PT$-symmetric dimer
Morales, J D Huerta; López-Aguayo, S; Rodríguez-Lara, B M
2016-01-01
Optics has proved a fertile ground for the experimental simulation of quantum mechanics. Most recently, optical realizations of $\\mathcal{PT}$-symmetric quantum mechanics have been shown, both theoretically and experimentally, opening the door to international efforts aiming at the design of practical optical devices exploiting this symmetry. Here, we focus on the optical $\\mathcal{PT}$-symmetric dimer, a two-waveguide coupler were the materials show symmetric effective gain and loss, and provide a review of the linear and nonlinear optical realizations from a symmetry based point of view. We go beyond a simple review of the literature and show that the dimer is just the smallest of a class of planar $N$-waveguide couplers that are the optical realization of Lorentz group in 2+1 dimensions. Furthermore, we provide a formulation to describe light propagation through waveguide couplers described by non-Hermitian mode coupling matrices based on a non-Hermitian generalization of Ehrenfest theorem.
Revisiting the Optical PT-Symmetric Dimer
Directory of Open Access Journals (Sweden)
José Delfino Huerta Morales
2016-08-01
Full Text Available Optics has proved a fertile ground for the experimental simulation of quantum mechanics. Most recently, optical realizations of PT -symmetric quantum mechanics have been shown, both theoretically and experimentally, opening the door to international efforts aiming at the design of practical optical devices exploiting this symmetry. Here, we focus on the optical PT -symmetric dimer, a two-waveguide coupler where the materials show symmetric effective gain and loss, and provide a review of the linear and nonlinear optical realizations from a symmetry-based point of view. We go beyond a simple review of the literature and show that the dimer is just the smallest of a class of planar N-waveguide couplers that are the optical realization of the Lorentz group in 2 + 1 dimensions. Furthermore, we provide a formulation to describe light propagation through waveguide couplers described by non-Hermitian mode coupling matrices based on a non-Hermitian generalization of the Ehrenfest theorem.
de Bont, Chris
2018-01-01
This booklet was written to share research results with farmers and practitioners in Tanzania. It gives a summary of the empirical material collected during three months of field work in the Mawala irrigation scheme (Kilimanjaro Region), and includes maps, tables and photos. It describes the history of the irrigation scheme, as well current irrigation and farming practices. It especially focuses on the different kinds of infrastructural improvement in the scheme (by farmers and the government...
A Relativistic Symmetrical Interpretation of Quantum Mechanics
Heaney, Michael B.
This poster describes a relativistic symmetrical interpretation (RSI) which postulates: quantum mechanics is intrinsically time-symmetric, with no arrow of time; the fundamental objects of quantum mechanics are transitions; a transition is fully described by a complex transition amplitude density with specified initial and final boundary conditions, and; transition amplitude densities never collapse. This RSI is compared to the Copenhagen Interpretation (CI) for the analysis of Einstein's bubble experiment using both the Dirac and Klein-Gordon equations. The RSI has no zitterbewegung in the particle's rest frame, resolves some inconsistencies of the CI, and gives intuitive explanations of some previously mysterious quantum effects.
Symmetry theorems via the continuous steiner symmetrization
Directory of Open Access Journals (Sweden)
L. Ragoub
2000-06-01
Full Text Available Using a new approach due to F. Brock called the Steiner symmetrization, we show first that if $u$ is a solution of an overdetermined problem in the divergence form satisfying the Neumann and non-constant Dirichlet boundary conditions, then $Omega$ is an N-ball. In addition, we show that we can relax the condition on the value of the Dirichlet boundary condition in the case of superharmonicity. Finally, we give an application to positive solutions of some semilinear elliptic problems in symmetric domains for the divergence case.
Negative-energy {P} {T}-symmetric Hamiltonians
Bender, Carl M.; Hook, Daniel W.; Klevansky, S. P.
2012-11-01
The non-Hermitian {P} {T}-symmetric quantum-mechanical Hamiltonian H = p2 + x2(ix)ɛ has real, positive and discrete eigenvalues for all ɛ ⩾ 0. These eigenvalues are analytic continuations of the harmonic-oscillator eigenvalues En = 2n + 1 (n = 0, 1, 2, 3, …) at ɛ = 0. However, the harmonic oscillator also has negative eigenvalues En = -2n - 1 (n = 0, 1, 2, 3, …), and one may ask whether it is equally possible to continue analytically from these eigenvalues. It is shown in this paper that for appropriate {P} {T}-symmetric boundary conditions the Hamiltonian H = p2 + x2(ix)ɛ also has real and negative discrete eigenvalues. The negative eigenvalues fall into classes labeled by the integer N (N = 1, 2, 3, …). For the Nth class of eigenvalues, ɛ lies in the range (4N - 6)/3 article is part of a special issue of Journal of Physics A: Mathematical and Theoretical devoted to ‘Quantum physics with non-Hermitian operators’.
Practical Leakage-Resilient Symmetric Cryptography
DEFF Research Database (Denmark)
Faust, Sebastian; Pietrzak, Krzysztof; Schipper, Joachim
2012-01-01
Leakage resilient cryptography attempts to incorporate side-channel leakage into the black-box security model and designs cryptographic schemes that are provably secure within it. Informally, a scheme is leakage-resilient if it remains secure even if an adversary learns a bounded amount of arbitr......Leakage resilient cryptography attempts to incorporate side-channel leakage into the black-box security model and designs cryptographic schemes that are provably secure within it. Informally, a scheme is leakage-resilient if it remains secure even if an adversary learns a bounded amount...
Picosecond optical nonlinearities in symmetrical and unsymmetrical ...
Indian Academy of Sciences (India)
We present our experimental results on the picosecond nonlinear optical. (NLO) studies of symmetrical and unsymmetrical phthalocyanines, examined using the. Z-scan technique. Both the open-aperture ... Z-scan measurements were performed using the amplified Ti:sapphire laser system. (LEGEND, Coherent) delivering ...
Cuspidal discrete series for semisimple symmetric spaces
DEFF Research Database (Denmark)
Andersen, Nils Byrial; Flensted-Jensen, Mogens; Schlichtkrull, Henrik
2012-01-01
We propose a notion of cusp forms on semisimple symmetric spaces. We then study the real hyperbolic spaces in detail, and show that there exists both cuspidal and non-cuspidal discrete series. In particular, we show that all the spherical discrete series are non-cuspidal. (C) 2012 Elsevier Inc. All...
Unidirectional Nonlinear PT-symmetric Optical Structures
Ramezani, Hamidreza; El-Ganainy, Ramy; Christodoulides, Demetrios N
2010-01-01
We show that non-linear optical structures involving a balanced gain-loss profile, can act as unidirectional optical valves. This is made possible by exploiting the interplay between the fundamental symmetries of parity (P) and time (T), with optical nonlinear effects. This novel unidirectional dynamics is specifically demonstrated for the case of an integrable PT-symmetric nonlinear system.
Efficient and convenient synthesis of symmetrical carboxylic ...
African Journals Online (AJOL)
An efficient and convenient procedure for the synthesis of symmetrical carboxylic anhydrides from carboxylic acids with sulfated zirconia by PEG-1000 phase transfer catalysis has been developed. The reactions proceeded under mild and solvent-free conditions to provide the carboxylic anhydrides in good to excellent ...
efficient and convenient synthesis of symmetrical carboxylic
African Journals Online (AJOL)
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ABSTRACT. An efficient and convenient procedure for the synthesis of symmetrical carboxylic anhydrides from carboxylic acids with sulfated zirconia by PEG-1000 phase transfer catalysis has been developed. The reactions proceeded under mild and solvent-free conditions to provide the carboxylic anhydrides in good to.
Fourier inversion on a reductive symmetric space
Ban, E.P. van den
1999-01-01
Let X be a semisimple symmetric space. In previous papers, [8] and [9], we have dened an explicit Fourier transform for X and shown that this transform is injective on the space C 1 c (X) ofcompactly supported smooth functions on X. In the present paper, which is a continuation of these papers, we
Biomechanical benefits of symmetrical strengthening of hip ...
African Journals Online (AJOL)
There is abundant literature encouraging athletes to engage in concurrent strength training. However, little emphasis is placed on the value of biomechanics with regard to symmetrical strengthening of force-couple relationships. A review of literature reveals 565 biomechanical papers versus 2085 physiological papers ...
Picosecond optical nonlinearities in symmetrical and unsymmetrical ...
Indian Academy of Sciences (India)
Home; Journals; Pramana – Journal of Physics; Volume 75; Issue 5. Picosecond optical nonlinearities in symmetrical and unsymmetrical phthalocyanines studied using the Z-scan technique. S Venugopal Rao P T Anusha L Giribabu Surya P Tewari. Conributed Papers Volume 75 Issue 5 November 2010 pp 1017-1023 ...
Symmetrized solutions for nonlinear stochastic differential equations
Directory of Open Access Journals (Sweden)
G. Adomian
1981-01-01
Full Text Available Solutions of nonlinear stochastic differential equations in series form can be put into convenient symmetrized forms which are easily calculable. This paper investigates such forms for polynomial nonlinearities, i.e., equations of the form Ly+ym=x where x is a stochastic process and L is a linear stochastic operator.
Exact solutions of the spherically symmetric multidimensional ...
African Journals Online (AJOL)
The complete orthonormalised energy eigenfunctions and the energy eigenvalues of the spherically symmetric isotropic harmonic oscillator in N dimensions, are obtained through the methods of separation of variables. Also, the degeneracy of the energy levels are examined. KEY WORDS: - Schrödinger Equation, Isotropic ...
Unary self-verifying symmetric difference automata
CSIR Research Space (South Africa)
Marais, Laurette
2016-07-01
Full Text Available We investigate self-verifying nondeterministic finite automata, in the case of unary symmetric difference nondeterministic finite automata (SV-XNFA). We show that there is a family of languages Ln=2 which can always be represented non...
Noncommutative spherically symmetric spacetimes at semiclassical order
Fritz, Christopher; Majid, Shahn
2017-07-01
Working within the recent formalism of Poisson-Riemannian geometry, we completely solve the case of generic spherically symmetric metric and spherically symmetric Poisson-bracket to find a unique answer for the quantum differential calculus, quantum metric and quantum Levi-Civita connection at semiclassical order O(λ) . Here λ is the deformation parameter, plausibly the Planck scale. We find that r, t, d r, d t are all forced to be central, i.e. undeformed at order λ, while for each value of r, t we are forced to have a fuzzy sphere of radius r with a unique differential calculus which is necessarily nonassociative at order λ2 . We give the spherically symmetric quantisation of the FLRW cosmology in detail and also recover a previous analysis for the Schwarzschild black hole, now showing that the quantum Ricci tensor for the latter vanishes at order λ. The quantum Laplace-Beltrami operator for spherically symmetric models turns out to be undeformed at order λ while more generally in Poisson-Riemannian geometry we show that it deforms to □f+λ2ωαβ(Ricγα-Sγα)(∇^βdf)γ+O(λ2) in terms of the classical Levi-Civita connection \\widehat\
The symmetric Mellin transform in quantum calculus
Directory of Open Access Journals (Sweden)
Brahim Kamel Brahim
2015-12-01
Full Text Available In this paper, we define the q-analogue of Mellin Transform symmetric under interchange of q and 1/q, and present some of its main properties and explore the possibility of using the integral transform to solve a class of differential equations q-differences.
Symmetric intersections of Rauzy fractals | Sellami | Quaestiones ...
African Journals Online (AJOL)
In this article we study symmetric subsets of Rauzy fractals of unimodular irreducible Pisot substitutions. The symmetry considered is re ection through the origin. Given an unimodular irreducible Pisot substitution, we consider the intersection of its Rauzy fractal with the Rauzy fractal of the reverse substitution. This set is ...
Stochastic calculus for symmetric Markov processes
Chen, Z.-Q.; Fitzsimmons, P.J.; Kuwae, K; Zhang, T.-S.
2008-01-01
Using time-reversal, we introduce a stochastic integral for zero-energy additive functionals of symmetric Markov processes, extending earlier work of S. Nakao. Various properties of such stochastic integrals are discussed and an It\\^{o} formula for Dirichlet processes is obtained.
The Mathematics of Symmetrical Factorial Designs
Indian Academy of Sciences (India)
The Mathematics of Symmetrical Factorial Designs. Mausumi Bose (nee Sen) obtained her MSc degree in. Statistics from the Calcutta. University and PhD degree from the Indian Statistical. Institute. She is on the faculty of the Indian. Statistical Institute. Her main field of research interest is design and analysis of experiments.
An investigation of embeddings for spherically symmetric ...
Indian Academy of Sciences (India)
symmetric spacetimes as they are relevant in astrophysics and cosmology, and we concen- trate on Einstein spaces because of their role in higher-dimensional particle physics, as well as their geometric simplicity. Because the usual method of solving the five-dimensional metric for a chosen four-dimensional space leads to ...
Spherically symmetric inhomogeneous dust collapse in higher ...
Indian Academy of Sciences (India)
Higher dimensional space-time; naked singularity; cosmic censorship. PACS Nos 04.20.Dw; 04.50. ... The existence of strong curvature naked singularities in gravitational collapse of spherically symmetric space-times ..... distributions (in an appropriate metric space) can be discussed along the lines of [16]. 3. Strength of the ...
The Mathematics of Symmetrical Factorial Designs
Indian Academy of Sciences (India)
Home; Journals; Resonance – Journal of Science Education; Volume 8; Issue 9. The Mathematics of Symmetrical Factorial Designs. Mausumi Bose. General Article Volume 8 Issue 9 September 2003 ... Author Affiliations. Mausumi Bose1. Applied Statistics Unit Indian Statistical Institute 203, BT Road Kolkata 700 108, India.
The Symmetric Rudin-Shapiro Transform
DEFF Research Database (Denmark)
Harbo, Anders La-Cour
2003-01-01
A method for constructing spread spectrum sequences is presented. The method is based on a linear, orthogonal, symmetric transform, the Rudin-Shapiro transform (RST), which is in many respects quite similar to the Haar wavelet packet transform. The RST provides the means for generating large sets...
Progressive symmetric exfoliative ichthyosis | Al Aboud | Sudanese ...
African Journals Online (AJOL)
... defined ichthyosiform patches on extremities. There is a history of similar condition in her cousin. We believe that this case represent a new autosomal recessive disorder of cornification that may be better refer to it as ''progressive symmetric exfoliative ichthyosis''. Sudanese Journal of Dermatology Vol. 3(3) 2005: 137-140 ...
Nonlinear eigenvalue problems and PT-symmetric quantum mechanics
Bender, Carl M.
2017-07-01
Semiclassical (WKB) techniques are commonly used to find the large-energy behavior of the eigenvalues of linear time-independent Schrödinger equations. In this talk we generalize the concept of an eigenvalue problem to nonlinear differential equations. The role of an eigenfunction is now played by a separatrix curve, and the special initial condition that gives rise to the separatrix curve is the eigenvalue. The Painlevé transcendents are examples of nonlinear eigenvalue problems, and semiclassical techniques are devised to calculate the behavior of the large eigenvalues. This behavior is found by reducing the Painlevé equation to the linear Schrödinger equation associated with a non-Hermitian PT-symmetric Hamiltonian. The concept of a nonlinear eigenvalue problem extends far beyond the Painlevé equations to huge classes of nonlinear differential equations.
Towards Symbolic Encryption Schemes
DEFF Research Database (Denmark)
Ahmed, Naveed; Jensen, Christian D.; Zenner, Erik
2012-01-01
, namely an authenticated encryption scheme that is secure under chosen ciphertext attack. Therefore, many reasonable encryption schemes, such as AES in the CBC or CFB mode, are not among the implementation options. In this paper, we report new attacks on CBC and CFB based implementations of the well...
Multiresolution signal decomposition schemes
J. Goutsias (John); H.J.A.M. Heijmans (Henk)
1998-01-01
textabstract[PNA-R9810] Interest in multiresolution techniques for signal processing and analysis is increasing steadily. An important instance of such a technique is the so-called pyramid decomposition scheme. This report proposes a general axiomatic pyramid decomposition scheme for signal analysis
Directory of Open Access Journals (Sweden)
R. Sitharthan
2016-09-01
Full Text Available This paper aims at modelling an electronically coupled distributed energy resource with an adaptive protection scheme. The electronically coupled distributed energy resource is a microgrid framework formed by coupling the renewable energy source electronically. Further, the proposed adaptive protection scheme provides a suitable protection to the microgrid for various fault conditions irrespective of the operating mode of the microgrid: namely, grid connected mode and islanded mode. The outstanding aspect of the developed adaptive protection scheme is that it monitors the microgrid and instantly updates relay fault current according to the variations that occur in the system. The proposed adaptive protection scheme also employs auto reclosures, through which the proposed adaptive protection scheme recovers faster from the fault and thereby increases the consistency of the microgrid. The effectiveness of the proposed adaptive protection is studied through the time domain simulations carried out in the PSCAD⧹EMTDC software environment.
Wu, Jiaye; Yang, Xiangbo
2017-10-30
In this paper, we construct a 1D PT-symmetric Thue-Morse aperiodic optical waveguide network (PTSTMAOWN) and mainly investigate the ultrastrong extraordinary transmission and reflection. We propose an approach to study the photonic modes and solve the problem of calculating photonic modes distributions in aperiodic networks due to the lack of dispersion functions and find that in a PTSTMAOWN there exist more photonic modes and more spontaneous PT-symmetric breaking points, which are quite different from other reported PT-symmetric optical systems. Additionally, we develop a method to sort spontaneous PT-symmetric breaking point zones to seek the strongest extraordinary point and obtain that at this point the strongest extraordinary transmission and reflection arrive at 2.96316 × 105 and 1.32761 × 105, respectively, due to the PT-symmetric coupling resonance and the special symmetry pattern of TM networks. These enormous gains are several orders of magnitude larger than the previous results. This optical system may possess potential in designing optical amplifier, optical logic elements in photon computers and ultrasensitive optical switches with ultrahigh monochromatity.
Symmetric protein architecture in protein design: top-down symmetric deconstruction.
Longo, Liam M; Blaber, Michael
2014-01-01
Top-down symmetric deconstruction (TDSD) is a joint experimental and computational approach to generate a highly stable, functionally benign protein scaffold for intended application in subsequent functional design studies. By focusing on symmetric protein folds, TDSD can leverage the dramatic reduction in sequence space achieved by applying a primary structure symmetric constraint to the design process. Fundamentally, TDSD is an iterative symmetrization process, in which the goal is to maintain or improve properties of thermodynamic stability and folding cooperativity inherent to a starting sequence (the "proxy"). As such, TDSD does not attempt to solve the inverse protein folding problem directly, which is computationally intractable. The present chapter will take the reader through all of the primary steps of TDSD-selecting a proxy, identifying potential mutations, establishing a stability/folding cooperativity screen-relying heavily on a successful TDSD solution for the common β-trefoil fold.
On the Generalized Degrees of Freedom of the K-user Symmetric MIMO Gaussian Interference Channel
Mohapatra, Parthajit
2011-01-01
This work derives inner and outer bounds on the generalized degrees of freedom (GDOF) of the K-user symmetric MIMO Gaussian interference channel (IC). For the inner bound, an achievable GDOF is derived by employing a combination of treating interference as noise, zero-forcing (ZF) at the receivers, interference alignment (IA), and extending the Han-Kobayashi (HK) scheme to K users, depending on the number of antennas and the INR/SNR level. An outer bound on the GDOF is derived, using a combination of the notion of cooperation and providing side information to the receivers. Several interesting conclusions are drawn from the expressions derived. For example, when K > N/M+1, a combination of the HK and IA schemes performs the best among the schemes considered. However, for N/M < K <= N/M+1, HK scheme outperforms other schemes and also found to be GDOF optimal. In this case, ZF-receiving coincides with HK scheme at alpha = 1 and GDOF optimal also.
A Modified Computational Scheme for the Stochastic Perturbation Finite Element Method
Directory of Open Access Journals (Sweden)
Feng Wu
Full Text Available Abstract A modified computational scheme of the stochastic perturbation finite element method (SPFEM is developed for structures with low-level uncertainties. The proposed scheme can provide second-order estimates of the mean and variance without differentiating the system matrices with respect to the random variables. When the proposed scheme is used, it involves finite analyses of deterministic systems. In the case of one random variable with a symmetric probability density function, the proposed computational scheme can even provide a result with fifth-order accuracy. Compared with the traditional computational scheme of SPFEM, the proposed scheme is more convenient for numerical implementation. Four numerical examples demonstrate that the proposed scheme can be used in linear or nonlinear structures with correlated or uncorrelated random variables.
Multiplication Symmetric Convolution Property for Discrete Trigonometric Transforms
Do Nyeon Kim; Rao, K.R.
2009-01-01
The symmetric-convolution multiplication (SCM) property of discrete trigonometric transforms (DTTs) based on unitary transform matrices is developed. Then as the reciprocity of this property, the novel multiplication symmetric-convolution (MSC) property of discrete trigonometric transforms, is developed.
Energy Technology Data Exchange (ETDEWEB)
Willcock, J J; Lumsdaine, A; Quinlan, D J
2008-08-19
Tabled execution is a generalization of memorization developed by the logic programming community. It not only saves results from tabled predicates, but also stores the set of currently active calls to them; tabled execution can thus provide meaningful semantics for programs that seemingly contain infinite recursions with the same arguments. In logic programming, tabled execution is used for many purposes, both for improving the efficiency of programs, and making tasks simpler and more direct to express than with normal logic programs. However, tabled execution is only infrequently applied in mainstream functional languages such as Scheme. We demonstrate an elegant implementation of tabled execution in Scheme, using a mix of continuation-passing style and mutable data. We also show the use of tabled execution in Scheme for a problem in formal language and automata theory, demonstrating that tabled execution can be a valuable tool for Scheme users.
Symmetric, discrete fractional splines and Gabor systems
DEFF Research Database (Denmark)
Søndergaard, Peter Lempel
2006-01-01
In this paper we consider fractional splines as windows for Gabor frames. We introduce two new types of symmetric, fractional splines in addition to one found by Unser and Blu. For the finite, discrete case we present two families of splines: One is created by sampling and periodizing the continu......In this paper we consider fractional splines as windows for Gabor frames. We introduce two new types of symmetric, fractional splines in addition to one found by Unser and Blu. For the finite, discrete case we present two families of splines: One is created by sampling and periodizing...... the continuous splines, and one is a truly finite, discrete construction. We discuss the properties of these splines and their usefulness as windows for Gabor frames and Wilson bases....
Representations of the infinite symmetric group
Borodin, Alexei
2016-01-01
Representation theory of big groups is an important and quickly developing part of modern mathematics, giving rise to a variety of important applications in probability and mathematical physics. This book provides the first concise and self-contained introduction to the theory on the simplest yet very nontrivial example of the infinite symmetric group, focusing on its deep connections to probability, mathematical physics, and algebraic combinatorics. Following a discussion of the classical Thoma's theorem which describes the characters of the infinite symmetric group, the authors describe explicit constructions of an important class of representations, including both the irreducible and generalized ones. Complete with detailed proofs, as well as numerous examples and exercises which help to summarize recent developments in the field, this book will enable graduates to enhance their understanding of the topic, while also aiding lecturers and researchers in related areas.
Young—Capelli symmetrizers in superalgebras†
Brini, Andrea; Teolis, Antonio G. B.
1989-01-01
Let Supern[U [unk] V] be the nth homogeneous subspace of the supersymmetric algebra of U [unk] V, where U and V are Z2-graded vector spaces over a field K of characteristic zero. The actions of the general linear Lie superalgebras pl(U) and pl(V) span two finite-dimensional K-subalgebras B and [unk] of EndK(Supern[U [unk] V]) that are the centralizers of each other. Young—Capelli symmetrizers and Young—Capelli *-symmetrizers give rise to K-linear bases of B and [unk] containing orthogonal systems of idempotents; thus they yield complete decompositions of B and [unk] into minimal left and right ideals, respectively. PMID:16594014
Axially symmetric static sources of gravitational field
Hernandez-Pastora, J. L.; Herrera, L.; Martin, J.
2016-12-01
A general procedure to find static and axially symmetric, interior solutions to the Einstein equations is presented. All the so obtained solutions, verify the energy conditions for a wide range of values of the parameters, and match smoothly to some exterior solution of the Weyl family, thereby representing globally regular models describing non-spherical sources of gravitational field. In the spherically symmetric limit, all our models converge to the well known incompressible perfect fluid solution. The key stone of our approach is based on an ansatz allowing to define the interior metric in terms of the exterior metric functions evaluated at the boundary source. Some particular sources are obtained, and the physical variables of the energy-momentum tensor are calculated explicitly, as well as the geometry of the source in terms of the relativistic multipole moments. The total mass of different configurations is also calculated, it is shown to be equal to the monopole of the exterior solution.
Factored Facade Acquisition using Symmetric Line Arrangements
Ceylan, Duygu
2012-05-01
We introduce a novel framework for image-based 3D reconstruction of urban buildings based on symmetry priors. Starting from image-level edges, we generate a sparse and approximate set of consistent 3D lines. These lines are then used to simultaneously detect symmetric line arrangements while refining the estimated 3D model. Operating both on 2D image data and intermediate 3D feature representations, we perform iterative feature consolidation and effective outlier pruning, thus eliminating reconstruction artifacts arising from ambiguous or wrong stereo matches. We exploit non-local coherence of symmetric elements to generate precise model reconstructions, even in the presence of a significant amount of outlier image-edges arising from reflections, shadows, outlier objects, etc. We evaluate our algorithm on several challenging test scenarios, both synthetic and real. Beyond reconstruction, the extracted symmetry patterns are useful towards interactive and intuitive model manipulations.
Coulomb's law in maximally symmetric spaces
Vakili, B.; Gorji, M. A.
2012-01-01
We study the modifications to the Coulomb's law when the background geometry is a $n$-dimensional maximally symmetric space, by using of the $n$-dimensional version of the Gauss' theorem. It is shown that some extra terms are added to the usual expression of the Coulomb electric field due to the curvature of the background space. Also, we consider the problem of existence of magnetic monopoles in such spaces and present analytical expressions for the corresponding magnetic fields and vector p...
Compensator configurations for load currents' symmetrization
Rusinaru, D.; Manescu, L. G.; Dinu, R. C.
2016-02-01
This paper approaches aspects regarding the mitigation effects of asymmetries in 3-phase 3-wire networks. The measure consisting in connecting of load current symmetrization devices at the load coupling point is presented. A time-variation of compensators parameters is determined as a function of the time-recorded electrical values. The general sizing principle of the load current symmetrization reactive components is based on a simple equivalent model of the unbalanced 3-phase loads. By using these compensators a certain control of the power components transits is ensured in the network. The control is based on the variations laws of the compensators parameters as functions of the recorded electrical values: [B] = [T]·[M]. The link between compensator parameters and measured values is ensured by a transformation matrix [T] for each operation conditions of the supply network. Additional conditions for improving of energy and efficiency performance of the compensator are considered: i.e. reactive power compensation. The compensator sizing algorithm was implemented into a MATLAB environment software, which generate the time-evolution of the parameters of load current symmetrization device. The input data of application takes into account time-recording of the electrical values. By using the compensator sizing software, some results were achieved for the case of a consumer connected at 20 kV busbar of a distribution substation, during 24 hours measurement session. Even the sizing of the compensators aimed some additional network operation aspects (power factor correction) correlated with the total or major load symmetrizations, the harmonics aspects of the network values were neglected.
Dirichlet forms and symmetric Markov processes
Oshima, Yoichi; Fukushima, Masatoshi
2010-01-01
Since the publication of the first edition in 1994, this book has attracted constant interests from readers and is by now regarded as a standard reference for the theory of Dirichlet forms. For the present second edition, the authors not only revised the existing text, but also added some new sections as well as several exercises with solutions. The book addresses to researchers and graduate students who wish to comprehend the area of Dirichlet forms and symmetric Markov processes.
Dynamic contributions to symmetric fragmentation processes
Schulte, H.; Jäckel, B.; Esterlund, R. A.; Knaack, M.; Westmeier, W.; Rox, A.; Patzelt, P.
1989-11-01
Angular-distribution anisotropies of fission/fissionlike products from the reactions 5.3 and 7.5 MeV/u 40Ar+ 197Au have been determined as a function of exit-channel mass asymmetry α. At sufficiently large α, the angular distributions become asymmetric about 90° in the rest frame, indicating that the symmetric fragmentation component in this system includes contributions from dynamic processes.
Irreducible complexity of iterated symmetric bimodal maps
Directory of Open Access Journals (Sweden)
J. P. Lampreia
2005-01-01
Full Text Available We introduce a tree structure for the iterates of symmetric bimodal maps and identify a subset which we prove to be isomorphic to the family of unimodal maps. This subset is used as a second factor for a ∗-product that we define in the space of bimodal kneading sequences. Finally, we give some properties for this product and study the ∗-product induced on the associated Markov shifts.
On bounds for symmetric divergence measures
Furuichi, S.; Yanagi, K.; Kuriyama, K.
2017-06-01
In the paper [1], tight bounds for symmetric divergence measures applying the results established by G.L.Gilardoni. In this article, we report on two kinds of extensions for the Sason's results, namely a classical q-extension and a non-commutative(quantum) extension. Especially, we improve Sason's bound of the summation of the absolute value for the difference between two probability distributions, applying the parameter q of Tsallis entropy, under a certain assumption.
An algebraic approach to symmetric extended formulations
Braun, Gábor; Pokutta, Sebastian
2012-01-01
Extended formulations are an important tool to obtain small (even compact) formulations of polytopes by representing them as projections of higher dimensional ones. It is an important question whether a polytope admits a small extended formulation, i.e., one involving only a polynomial number of inequalities in its dimension. For the case of symmetric extended formulations (i.e., preserving the symmetries of the polytope) Yannakakis established a powerful technique to derive lower bounds and ...
Resistor Networks based on Symmetrical Polytopes
Directory of Open Access Journals (Sweden)
Jeremy Moody
2015-03-01
Full Text Available This paper shows how a method developed by Van Steenwijk can be generalized to calculate the resistance between any two vertices of a symmetrical polytope all of whose edges are identical resistors. The method is applied to a number of cases that have not been studied earlier such as the Archimedean polyhedra and their duals in three dimensions, the regular polytopes in four dimensions and the hypercube in any number of dimensions.
A Symmetric Algorithm for Golden Ratio in Hyper-Horadam Numbers
Directory of Open Access Journals (Sweden)
Mustafa Bahşi
2016-01-01
Full Text Available We study some ratios related to hyper-Horadam numbers such as Wnr/Wn-1r while n→∞ by using a symmetric algorithm obtained by the recurrence relation ank=ank-1+an-1k, where Wnr is the nth hyper-Horadam number. Also, we give some special cases of these ratios such as the golden ratio and silver ratio.
Spherically symmetric thick branes cosmological evolution
Bernardini, A. E.; Cavalcanti, R. T.; da Rocha, Roldão
2015-01-01
Spherically symmetric time-dependent solutions for the 5D system of a scalar field canonically coupled to gravity are obtained and identified as an extension of recent results obtained by Ahmed et al. (JHEP 1404:061. arXiv:1312.3576 [hep-th], 2014). The corresponding cosmology of models with regularized branes generated by such a 5D scalar field scenario is also investigated. It has been shown that the anisotropic evolution of the warp factor and consequently the Hubble like parameter are both driven by the radial coordinate on the brane, which leads to an emergent thick brane-world scenario with spherically symmetric time dependent warp factor. Meanwhile, the separability of variables depending on fifth dimension, , which is exhibited by the equations of motion, allows one to recover the extra dimensional profiles obtained in Ahmed et al. (2014), namely the extra dimensional part of the scale (warp) factor and the scalar field dependence on . Therefore, our results are mainly concerned with the time dependence of a spherically symmetric warp factor. Besides evincing possibilities for obtaining asymmetric stable brane-world scenarios, the extra dimensional profiles here obtained can also be reduced to those ones investigated in Ahmed et al. (2014).
Song, Yi; Ni, Jiang-Li; Wang, Zhang-Yin; Lu, Yan; Han, Lian-Fang
2017-10-01
We present a new scheme for deterministically realizing the mutual interchange of quantum information between two distant parties via selected quantum states as the shared entangled resource. We first show the symmetric bidirectional remote state preparation (BRSP), where two single-qubit quantum states will be simultaneously exchanged in a deterministic manner provided that each of the users performs single-qubit von Neumann measurements with proper measurement bases as well as appropriate unitary operations, depending essentially on the outcomes of the prior measurements. Then we consider to extend the symmetric protocol to an asymmetric case, in which BRSP of a general single-qubit state and an arbitrary two-qubit state is investigated successfully. The necessary quantum operations and the employed quantum resources are feasible according to the present technology, resulting in that this protocol may be realizable in the realm of current physical experiment.
Ma, Lihong; Jin, Weimin
2018-01-01
A novel symmetric and asymmetric hybrid optical cryptosystem is proposed based on compressive sensing combined with computer generated holography. In this method there are six encryption keys, among which two decryption phase masks are different from the two random phase masks used in the encryption process. Therefore, the encryption system has the feature of both symmetric and asymmetric cryptography. On the other hand, because computer generated holography can flexibly digitalize the encrypted information and compressive sensing can significantly reduce data volume, what is more, the final encryption image is real function by phase truncation, the method favors the storage and transmission of the encryption data. The experimental results demonstrate that the proposed encryption scheme boosts the security and has high robustness against noise and occlusion attacks.
On the harmonic starlike functions with respect to symmetric ...
African Journals Online (AJOL)
In the present paper, we introduce the notions of functions harmonic starlike with respect to symmetric, conjugate and symmetric conjugate points. Such results as coefficient inequalities and structural formulae for these function classes are proved. Keywords: Harmonic functions, harmonic starlike functions, symmetric points, ...
14 CFR 23.331 - Symmetrical flight conditions.
2010-01-01
... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Symmetrical flight conditions. 23.331... Flight Loads § 23.331 Symmetrical flight conditions. (a) The appropriate balancing horizontal tail load... inertia loads corresponding to any of the symmetrical flight conditions specified in §§ 23.333 through 23...
A Digital Signature Scheme Based on MST3 Cryptosystems
Directory of Open Access Journals (Sweden)
Haibo Hong
2014-01-01
Full Text Available As special types of factorization of finite groups, logarithmic signature and cover have been used as the main components of cryptographic keys for secret key cryptosystems such as PGM and public key cryptosystems like MST1, MST2, and MST3. Recently, Svaba et. al proposed a revised MST3 encryption scheme with greater security. Meanwhile, they put forward an idea of constructing signature schemes on the basis of logarithmic signatures and random covers. In this paper, we firstly design a secure digital signature scheme based on logarithmic signatures and random covers. In order to complete the task, we devise a new encryption scheme based on MST3 cryptosystems.
Energy Technology Data Exchange (ETDEWEB)
Bonaventura, L. [GKSS-Forschungszentrum Geesthacht GmbH (Germany). Inst. fuer Hydrophysik
1998-12-31
A semiimplicit, semiLagrangian scheme for the fully compressible Euler equations of the atmosphere has been developed using a Cartesian coordinate system with height as the vertical coordinate. As a result, an efficient algorithm is obtained, which only requires the solution of a symmetric and well conditioned system at each timestep. Furthermore, no spurious flows are generated around steep orography. Numerical simulations of well known lee wave test cases demonstrate the soundness and feasibility of the proposed scheme. (orig.) 34 refs.
Semantically Secure Symmetric Encryption with Error Correction for Distributed Storage
Directory of Open Access Journals (Sweden)
Juha Partala
2017-01-01
Full Text Available A distributed storage system (DSS is a fundamental building block in many distributed applications. It applies linear network coding to achieve an optimal tradeoff between storage and repair bandwidth when node failures occur. Additively homomorphic encryption is compatible with linear network coding. The homomorphic property ensures that a linear combination of ciphertext messages decrypts to the same linear combination of the corresponding plaintext messages. In this paper, we construct a linearly homomorphic symmetric encryption scheme that is designed for a DSS. Our proposal provides simultaneous encryption and error correction by applying linear error correcting codes. We show its IND-CPA security for a limited number of messages based on binary Goppa codes and the following assumption: when dividing a scrambled generator matrix G^ into two parts G1^ and G2^, it is infeasible to distinguish G2^ from random and to find a statistical connection between G1^ and G2^. Our infeasibility assumptions are closely related to those underlying the McEliece public key cryptosystem but are considerably weaker. We believe that the proposed problem has independent cryptographic interest.
Energy Technology Data Exchange (ETDEWEB)
Placidi, M.; Jung, J. -Y.; Ratti, A.; Sun, C.
2014-07-25
This paper describes beam distribution schemes adopting a novel implementation based on low amplitude vertical deflections combined with horizontal ones generated by Lambertson-type septum magnets. This scheme offers substantial compactness in the longitudinal layouts of the beam lines and increased flexibility for beam delivery of multiple beam lines on a shot-to-shot basis. Fast kickers (FK) or transverse electric field RF Deflectors (RFD) provide the low amplitude deflections. Initially proposed at the Stanford Linear Accelerator Center (SLAC) as tools for beam diagnostics and more recently adopted for multiline beam pattern schemes, RFDs offer repetition capabilities and a likely better amplitude reproducibility when compared to FKs, which, in turn, offer more modest financial involvements both in construction and operation. Both solutions represent an ideal approach for the design of compact beam distribution systems resulting in space and cost savings while preserving flexibility and beam quality.
Marlet, Renaud
2013-01-01
This book presents the principles and techniques of program specialization - a general method to make programs faster (and possibly smaller) when some inputs can be known in advance. As an illustration, it describes the architecture of Tempo, an offline program specializer for C that can also specialize code at runtime, and provides figures for concrete applications in various domains. Technical details address issues related to program analysis precision, value reification, incomplete program specialization, strategies to exploit specialized program, incremental specialization, and data speci
A smart nonstandard finite difference scheme for second order nonlinear boundary value problems
Erdogan, Utku; Ozis, Turgut
2011-01-01
A new kind of finite difference scheme is presented for special second order nonlinear two point boundary value problems. An artificial parameter is introduced in the scheme. Symbolic computation is proposed for the construction of the scheme. Local truncation error of the method is discussed.
Nanotribology of Symmetric and Asymmetric Liquid Lubricants
Directory of Open Access Journals (Sweden)
Shinji Yamada
2010-03-01
Full Text Available When liquid molecules are confined in a narrow gap between smooth surfaces, their dynamic properties are completely different from those of the bulk. The molecular motions are highly restricted and the system exhibits solid-like responses when sheared slowly. This solidification behavior is very dependent on the molecular geometry (shape of liquids because the solidification is induced by the packing of molecules into ordered structures in confinement. This paper reviews the measurements of confined structures and friction of symmetric and asymmetric liquid lubricants using the surface forces apparatus. The results show subtle and complex friction mechanisms at the molecular scale.
Symmetry theorems via the continuous steiner symmetrization
L. Ragoub
2000-01-01
Using a new approach due to F. Brock called the Steiner symmetrization, we show first that if $u$ is a solution of an overdetermined problem in the divergence form satisfying the Neumann and non-constant Dirichlet boundary conditions, then $Omega$ is an N-ball. In addition, we show that we can relax the condition on the value of the Dirichlet boundary condition in the case of superharmonicity. Finally, we give an application to positive solutions of some semilinear elliptic problems in symmet...
Cryptanalysis of Some Lightweight Symmetric Ciphers
DEFF Research Database (Denmark)
Abdelraheem, Mohamed Ahmed Awadelkareem Mohamed Ahmed
In recent years, the need for lightweight encryption systems has been increasing as many applications use RFID and sensor networks which have a very low computational power and thus incapable of performing standard cryptographic operations. In response to this problem, the cryptographic community...... of the international standards in lightweight cryptography. This thesis aims at analyzing and evaluating the security of some the recently proposed lightweight symmetric ciphers with a focus on PRESENT-like ciphers, namely, the block cipher PRESENT and the block cipher PRINTcipher. We provide an approach to estimate...
A complete hierarchical key management scheme for heterogeneous wireless sensor networks.
Chen, Chien-Ming; Zheng, Xinying; Wu, Tsu-Yang
2014-01-01
Heterogeneous cluster-based wireless sensor networks (WSN) attracted increasing attention recently. Obviously, the clustering makes the entire networks hierarchical; thus, several kinds of keys are required for hierarchical network topology. However, most existing key management schemes for it place more emphasis on pairwise key management schemes or key predistribution schemes and neglect the property of hierarchy. In this paper, we propose a complete hierarchical key management scheme which only utilizes symmetric cryptographic algorithms and low cost operations for heterogeneous cluster-based WSN. Our scheme considers four kinds of keys, which are an individual key, a cluster key, a master key, and pairwise keys, for each sensor node. Finally, the analysis and experiments demonstrate that the proposed scheme is secure and efficient; thus, it is suitable for heterogeneous cluster-based WSN.
Indian Academy of Sciences (India)
Home; Journals; Resonance – Journal of Science Education; Volume 6; Issue 2. Electronic Commerce - Payment Schemes. V Rajaraman. Series Article Volume 6 Issue 2 February 2001 pp 6-13. Fulltext. Click here to view fulltext PDF. Permanent link: http://www.ias.ac.in/article/fulltext/reso/006/02/0006-0013 ...
Alternative health insurance schemes
DEFF Research Database (Denmark)
Keiding, Hans; Hansen, Bodil O.
2002-01-01
In this paper, we present a simple model of health insurance with asymmetric information, where we compare two alternative ways of organizing the insurance market. Either as a competitive insurance market, where some risks remain uninsured, or as a compulsory scheme, where however, the level...... competitive insurance; this situation turns out to be at least as good as either of the alternatives...
Symmetric solutions of evolutionary partial differential equations
Bruell, Gabriele; Ehrnström, Mats; Geyer, Anna; Pei, Long
2017-10-01
We show that for a large class of evolutionary nonlinear and nonlocal partial differential equations, symmetry of solutions implies very restrictive properties of the solutions and symmetry axes. These restrictions are formulated in terms of three principles, based on the structure of the equations. The first principle covers equations that allow for steady solutions and shows that any spatially symmetric solution is in fact steady with a speed determined by the motion of the axis of symmetry at the initial time. The second principle includes equations that admit breathers and steady waves, and therefore is less strong: it holds that the axes of symmetry are constant in time. The last principle is a mixed case, when the equation contains terms of the kind from both earlier principles, and there may be different outcomes; for a class of such equations one obtains that a spatially symmetric solution must be constant in both time and space. We list and give examples of more than 30 well-known equations and systems in one and several dimensions satisfying these principles; corresponding results for weak formulations of these equations may be attained using the same techniques. Our investigation is a generalisation of a local and one-dimensional version of the first principle from Ehrnström et al (2009 Int. Math. Res. Not. 2009 4578-96) to nonlocal equations, systems and higher dimensions, as well as a study of the standing and mixed cases.
Electroweak Baryogenesis in R-symmetric Supersymmetry
Energy Technology Data Exchange (ETDEWEB)
Fok, R.; Kribs, Graham D.; Martin, Adam; Tsai, Yuhsin
2013-03-01
We demonstrate that electroweak baryogenesis can occur in a supersymmetric model with an exact R-symmetry. The minimal R-symmetric supersymmetric model contains chiral superfields in the adjoint representation, giving Dirac gaugino masses, and an additional set of "R-partner" Higgs superfields, giving R-symmetric \\mu-terms. New superpotential couplings between the adjoints and the Higgs fields can simultaneously increase the strength of the electroweak phase transition and provide additional tree-level contributions to the lightest Higgs mass. Notably, no light stop is present in this framework, and in fact, we require both stops to be above a few TeV to provide sufficient radiative corrections to the lightest Higgs mass to bring it up to 125 GeV. Large CP-violating phases in the gaugino/higgsino sector allow us to match the baryon asymmetry of the Universe with no constraints from electric dipole moments due to R-symmetry. We briefly discuss some of the more interesting phenomenology, particularly of the of the lightest CP-odd scalar.
Experimental insertions made of two symmetric triplets
D'Amico, T E
1998-01-01
The reported study is based on the analytical treatment developed for an experimental collider insertion made of two symmetric triplets,the inner triplet located near the interaction point (IP) and th e outer triplet preceding a regular lattice. These two triplets are assumed to be symmetric in their geometry and quadrupole strengths, but not in their Twiss parameters. The method is applied to an i nsertion of the type of an experimental LHC insertion. The drift between the IP and the first quadrupole is fixed and the inner triplet is constrained to achieve a beta-crossing with equal and opposit e slopes (alpha-values) in the two planes. The outer triplet acts then as a FODO transformer from beta-crossing to beta-crossing in order to match the lattice. The analysis provides in a given paramet er interval all the existing solutions for the distance between triplets and the total insertion length, as functions of one gradient and the quadrupole separation in the inner triplet. The variation of the quadrupole st...
The modelling of symmetric airfoil vortex generators
Reichert, B. A.; Wendt, B. J.
1996-01-01
An experimental study is conducted to determine the dependence of vortex generator geometry and impinging flow conditions on shed vortex circulation and crossplane peak vorticity for one type of vortex generator. The vortex generator is a symmetric airfoil having a NACA 0012 cross-sectional profile. The geometry and flow parameters varied include angle-of-attack alfa, chordlength c, span h, and Mach number M. The vortex generators are mounted either in isolation or in a symmetric counter-rotating array configuration on the inside surface of a straight pipe. The turbulent boundary layer thickness to pipe radius ratio is delta/R = 0. 17. Circulation and peak vorticity data are derived from crossplane velocity measurements conducted at or about 1 chord downstream of the vortex generator trailing edge. Shed vortex circulation is observed to be proportional to M, alfa, and h/delta. With these parameters held constant, circulation is observed to fall off in monotonic fashion with increasing airfoil aspect ratio AR. Shed vortex peak vorticity is also observed to be proportional to M, alfa, and h/delta. Unlike circulation, however, peak vorticity is observed to increase with increasing aspect ratio, reaching a peak value at AR approx. 2.0 before falling off.
Analysis of non-symmetrical flapping airfoils
Tay, W. B.; Lim, K. B.
2009-08-01
Simulations have been done to assess the lift, thrust and propulsive efficiency of different types of non-symmetrical airfoils under different flapping configurations. The variables involved are reduced frequency, Strouhal number, pitch amplitude and phase angle. In order to analyze the variables more efficiently, the design of experiments using the response surface methodology is applied. Results show that both the variables and shape of the airfoil have a profound effect on the lift, thrust, and efficiency. By using non-symmetrical airfoils, average lift coefficient as high as 2.23 can be obtained. The average thrust coefficient and efficiency also reach high values of 2.53 and 0.61, respectively. The lift production is highly dependent on the airfoil’s shape while thrust production is influenced more heavily by the variables. Efficiency falls somewhere in between. Two-factor interactions are found to exist among the variables. This shows that it is not sufficient to analyze each variable individually. Vorticity diagrams are analyzed to explain the results obtained. Overall, the S1020 airfoil is able to provide relatively good efficiency and at the same time generate high thrust and lift force. These results aid in the design of a better ornithopter’s wing.
Trade Specialization Indices: Two Competing Models
Saleh, Samsubar; Widodo, Tri
2010-01-01
Revealed Comparative Advantage (RCA) index by Balassa (1965) is intensively applied in empirical studies on countries’ comparative advantage or trade specialization.Asymmetric problem in the criteria of RCA index encourages Dalum et al. (1998) and Laursen (1998) to make Revealed Symmetric Comparative Advantage (RSCA) index. Thesetwo indexes are commonly employed in econometric models for analyzing countries’ trade specialization. This paper aims to compare theoretically and empirically the tw...
An effective and secure key-management scheme for hierarchical access control in E-medicine system.
Odelu, Vanga; Das, Ashok Kumar; Goswami, Adrijit
2013-04-01
Recently several hierarchical access control schemes are proposed in the literature to provide security of e-medicine systems. However, most of them are either insecure against 'man-in-the-middle attack' or they require high storage and computational overheads. Wu and Chen proposed a key management method to solve dynamic access control problems in a user hierarchy based on hybrid cryptosystem. Though their scheme improves computational efficiency over Nikooghadam et al.'s approach, it suffers from large storage space for public parameters in public domain and computational inefficiency due to costly elliptic curve point multiplication. Recently, Nikooghadam and Zakerolhosseini showed that Wu-Chen's scheme is vulnerable to man-in-the-middle attack. In order to remedy this security weakness in Wu-Chen's scheme, they proposed a secure scheme which is again based on ECC (elliptic curve cryptography) and efficient one-way hash function. However, their scheme incurs huge computational cost for providing verification of public information in the public domain as their scheme uses ECC digital signature which is costly when compared to symmetric-key cryptosystem. In this paper, we propose an effective access control scheme in user hierarchy which is only based on symmetric-key cryptosystem and efficient one-way hash function. We show that our scheme reduces significantly the storage space for both public and private domains, and computational complexity when compared to Wu-Chen's scheme, Nikooghadam-Zakerolhosseini's scheme, and other related schemes. Through the informal and formal security analysis, we further show that our scheme is secure against different attacks and also man-in-the-middle attack. Moreover, dynamic access control problems in our scheme are also solved efficiently compared to other related schemes, making our scheme is much suitable for practical applications of e-medicine systems.
Phase transition in the PT-symmetric spin-1/2 quantum chain
Karnaukhov, Igor N.
2012-11-01
We study a PT-symmetric spin-1/2 chain in which spins are located at the vertices connected and exchange interact along links. The model presented has exact solution for arbitrary values of the exchange integrals. The ground-state phase diagram consists of two states with different static Z2 gauge fields; all Z2 charges are equal to +1 or -1. These states are separated by a quantum critical point ψc = π/4, ψc is a critical value of the phase, that defines the PT-symmetric exchange interactions of spins inside the cell. The single-particle spectrum of the Majorana fermions in the sectors with uniform fluxes is defined by flat-band fermion states at ψ = 0, π/2 and band states at 0 article is part of a special issue of Journal of Physics A: Mathematical and Theoretical devoted to ‘Quantum physics with non-Hermitian operators’.
Fuzzy Pattern Recognition Based on Symmetric Fuzzy Relative Entropy
Shi, Y F; He, L.H.; Chen, J.
2009-01-01
Based on fuzzy similarity degree, entropy, relative entropy and fuzzy entropy, the symmetric fuzzy relative entropy is presented, which not only has a full physical meaning, but also has succinct practicability. The symmetric fuzzy relative entropy can be used to measure the divergence between different fuzzy patterns. The example demonstrates that the symmetric fuzzy relative entropy is valid and reliable for fuzzy pattern recognition and classification, and its classification precision is v...
Selectively strippable paint schemes
Stein, R.; Thumm, D.; Blackford, Roger W.
1993-03-01
In order to meet the requirements of more environmentally acceptable paint stripping processes many different removal methods are under evaluation. These new processes can be divided into mechanical and chemical methods. ICI has developed a paint scheme with intermediate coat and fluid resistant polyurethane topcoat which can be stripped chemically in a short period of time with methylene chloride free and phenol free paint strippers.
Geometric inequalities in spherically symmetric spacetimes
Csukás, Károly Z.
2017-07-01
In geometric inequalities ADM mass plays more fundamental role than the concept of quasi-local mass. This paper is to demonstrate that using the quasi-local mass some new insights can be acquired. In spherically symmetric spacetimes the Misner-Sharp mass and the concept of the Kodama vector field provides an ideal setting to the investigations of geometric inequalities. We applying the proposed new techniques to investigate the spacetimes containing black hole or cosmological horizons but we shall also apply them in context of normal bodies. Most of the previous investigations applied only the quasi-local charges and the area. Our main point is to include the quasi-local mass in the corresponding geometrical inequalities. This way we recover some known relations but new inequalities are also derived.
Primordial two-component maximally symmetric inflation
Enqvist, K.; Nanopoulos, D. V.; Quirós, M.; Kounnas, C.
1985-12-01
We propose a two-component inflation model, based on maximally symmetric supergravity, where the scales of reheating and the inflation potential at the origin are decoupled. This is possible because of the second-order phase transition from SU(5) to SU(3)×SU(2)×U(1) that takes place when φ≅φcinflation at the global minimum, and leads to a reheating temperature TR≅(1015-1016) GeV. This makes it possible to generate baryon asymmetry in the conventional way without any conflict with experimental data on proton lifetime. The mass of the gravitinos is m3/2≅1012 GeV, thus avoiding the gravitino problem. Monopoles are diluted by residual inflation in the broken phase below the cosmological bounds if φcUSA.
Scaling model for symmetric star polymers
Ramachandran, Ram; Rai, Durgesh K.; Beaucage, Gregory
2010-03-01
Neutron scattering data from symmetric star polymers with six poly (urethane-ether) arms, chemically bonded to a C-60 molecule are fitted using a new scaling model and scattering function. The new scaling function can describe both good solvent and theta solvent conditions as well as resolve deviations in chain conformation due to steric interactions between star arms. The scaling model quantifies the distinction between invariant topological features for this star polymer and chain tortuosity which changes with goodness of solvent and steric interaction. Beaucage G, Phys. Rev. E 70 031401 (2004).; Ramachandran R, et al. Macromolecules 41 9802-9806 (2008).; Ramachandran R, et al. Macromolecules, 42 4746-4750 (2009); Rai DK et al. Europhys. Lett., (Submitted 10/2009).
Laziness of Symmetric and Separable States
S P, Suma; Sirsi, Swarnamala
2017-07-01
An N-partite state is considered lazy, if the entropy rate of one subsystem with respect to time is zero under any coupling to the other subsystems. In this paper, we show that all biaxial or purely second rank tensor polarized systems are lazy. Such a system can be produced in the laboratory by the interaction of a spin-1 nuclei with non-zero quadrupole moment like H 2, N 14 with an external quadrupole field found in suitable crystal lattice. We then investigate the 'laziness'(property of the system to be lazy) of N-qubit mixed symmetric separable states and enumerate the conditions for them to be lazy. Further, we study the laziness of direct product states on application of a global and local noisy channels.
Bidding behavior in a symmetric Chinese auction
Directory of Open Access Journals (Sweden)
Mauricio Benegas
2015-01-01
Full Text Available This paper purposes a symmetric all-pay auction where the bidders compete neither for an object nor the object itself but for a lottery on receive. That lottery is determined endogenously through the bids. This auction is known as chance auction or more popularly as Chinese auction. The model considers the possibility that for some bidders the optimal strategy is to bid zero and to rely on luck. It showed that bidders become less aggressive when the lottery satisfies a variational condition. It was also shown that luck factor is decisive to determine if the expected payoff in Chinese auction is bigger or smaller than expected payoff in standard all-pay auction.
Minimal Left-Right Symmetric Dark Matter.
Heeck, Julian; Patra, Sudhanwa
2015-09-18
We show that left-right symmetric models can easily accommodate stable TeV-scale dark matter particles without the need for an ad hoc stabilizing symmetry. The stability of a newly introduced multiplet either arises accidentally as in the minimal dark matter framework or comes courtesy of the remaining unbroken Z_{2} subgroup of B-L. Only one new parameter is introduced: the mass of the new multiplet. As minimal examples, we study left-right fermion triplets and quintuplets and show that they can form viable two-component dark matter. This approach is, in particular, valid for SU(2)×SU(2)×U(1) models that explain the recent diboson excess at ATLAS in terms of a new charged gauge boson of mass 2 TeV.
Symmetric functions and B sub N -invariant spherical harmonics
Dunkl, C F
2002-01-01
The wavefunctions of a quantum isotropic harmonic oscillator modified by reflecting barriers at the coordinate planes in N-dimensional space can be expressed in terms of certain generalized spherical harmonics. These are associated with a product-type weight function on the sphere. Their analysis is carried out by means of differential-difference operators. The symmetries of this system involve the Weyl group of type B, generated by permutations and changes of sign of the coordinates. A new basis for symmetric functions as well as an explicit transition matrix to the monomial basis is constructed. This basis leads to a basis for invariant spherical harmonics. The determinant of the Gram matrix for the basis in the natural inner product over the sphere is evaluated. When the underlying parameter is specialized to zero, the basis consists of ordinary spherical harmonics with cube group symmetry, as used for wavefunctions of electrons in crystals. The harmonic oscillator can also be considered as a degenerate in...
Uncertainty evaluation method for axi-symmetric measurement machines
Directory of Open Access Journals (Sweden)
Muelaner Jody Emlyn
2016-01-01
Full Text Available This paper describes a method of uncertainty evaluation for axi-symmetric measurement machines. Specialized measuring machines for the inspection of axisymmetric components enable the measurement of properties such as roundness (radial runout, axial runout and coning. These machines typically consist of a rotary table and a number of contact measurement probes located on slideways. Sources of uncertainty include the probe calibration process, probe repeatability, probe alignment, geometric errors in the rotary table, the dimensional stability of the structure holding the probes and form errors in the reference hemisphere which is used to calibrate the system. The generic method is described and an evaluation of an industrial machine is described as a worked example. Expanded uncertainties, at 95% confidence, were then calculated for the measurement of; radial runout (1.2 μm with a plunger probe or 1.7 μm with a lever probe; axial runout (1.2 μm with a plunger probe or 1.5 μm with a lever probe; and coning/swash (0.44 arcseconds with a plunger probe or 0.60 arcseconds with a lever probe.
14 CFR 25.331 - Symmetric maneuvering conditions.
2010-01-01
... AIRCRAFT AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY AIRPLANES Structure Flight Maneuver and Gust Conditions § 25.331 Symmetric maneuvering conditions. (a) Procedure. For the analysis of the maneuvering...
Symmetric Markov Processes, Time Change, and Boundary Theory (LMS-35)
Chen, Zhen-Qing
2011-01-01
This book gives a comprehensive and self-contained introduction to the theory of symmetric Markov processes and symmetric quasi-regular Dirichlet forms. In a detailed and accessible manner, Zhen-Qing Chen and Masatoshi Fukushima cover the essential elements and applications of the theory of symmetric Markov processes, including recurrence/transience criteria, probabilistic potential theory, additive functional theory, and time change theory. The authors develop the theory in a general framework of symmetric quasi-regular Dirichlet forms in a unified manner with that of regular Dirichlet forms
FFLP problem with symmetric trapezoidal fuzzy numbers
Directory of Open Access Journals (Sweden)
Reza Daneshrad
2015-04-01
Full Text Available The most popular approach for solving fully fuzzy linear programming (FFLP problems is to convert them into the corresponding deterministic linear programs. Khan et al. (2013 [Khan, I. U., Ahmad, T., & Maan, N. (2013. A simplified novel technique for solving fully fuzzy linear programming problems. Journal of Optimization Theory and Applications, 159(2, 536-546.] claimed that there had been no method in the literature to find the fuzzy optimal solution of a FFLP problem without converting it into crisp linear programming problem, and proposed a technique for the same. Others showed that the fuzzy arithmetic operation used by Khan et al. (2013 had some problems in subtraction and division operations, which could lead to misleading results. Recently, Ezzati et al. (2014 [Ezzati, R., Khorram, E., & Enayati, R. (2014. A particular simplex algorithm to solve fuzzy lexicographic multi-objective linear programming problems and their sensitivity analysis on the priority of the fuzzy objective functions. Journal of Intelligent and Fuzzy Systems, 26(5, 2333-2358.] defined a new operation on symmetric trapezoidal fuzzy numbers and proposed a new algorithm to find directly a lexicographic/preemptive fuzzy optimal solution of a fuzzy lexicographic multi-objective linear programming problem by using new fuzzy arithmetic operations, but their model was not fully fuzzy optimization. In this paper, a new method, by using Ezzati et al. (2014’s fuzzy arithmetic operation and a fuzzy version of simplex algorithm, is proposed for solving FFLP problem whose parameters are represented by symmetric trapezoidal fuzzy number without converting the given problem into crisp equivalent problem. By using the proposed method, the fuzzy optimal solution of FFLP problem can be easily obtained. A numerical example is provided to illustrate the proposed method.
Symmetric Topological Phases and Tensor Network States
Jiang, Shenghan
Classification and simulation of quantum phases are one of main themes in condensed matter physics. Quantum phases can be distinguished by their symmetrical and topological properties. The interplay between symmetry and topology in condensed matter physics often leads to exotic quantum phases and rich phase diagrams. Famous examples include quantum Hall phases, spin liquids and topological insulators. In this thesis, I present our works toward a more systematically understanding of symmetric topological quantum phases in bosonic systems. In the absence of global symmetries, gapped quantum phases are characterized by topological orders. Topological orders in 2+1D are well studied, while a systematically understanding of topological orders in 3+1D is still lacking. By studying a family of exact solvable models, we find at least some topological orders in 3+1D can be distinguished by braiding phases of loop excitations. In the presence of both global symmetries and topological orders, the interplay between them leads to new phases termed as symmetry enriched topological (SET) phases. We develop a framework to classify a large class of SET phases using tensor networks. For each tensor class, we can write down generic variational wavefunctions. We apply our method to study gapped spin liquids on the kagome lattice, which can be viewed as SET phases of on-site symmetries as well as lattice symmetries. In the absence of topological order, symmetry could protect different topological phases, which are often referred to as symmetry protected topological (SPT) phases. We present systematic constructions of tensor network wavefunctions for bosonic symmetry protected topological (SPT) phases respecting both onsite and spatial symmetries.
Dynamical systems and spherically symmetric cosmological models
He, Yanjing
2006-06-01
In this thesis we present a study of the timelike self-similar spherically symmetric cosmological models with two scalar fields with exponential potentials. We first define precisely the timelike self-similar spherically symmetric (TSS) spacetimes. We write the TSS metric in a conformally isometric form in a coordinate system adapted to the geometry of the spacetime manifold. In this coordinate system, both the metric functions of the TSS spacetimes and the potential functions of the scalar fields can be simplified to four undetermined functions of a single coordinate. As a result, the Einstein field equations reduce to an autonomous system of first-order ODEs and polynomial constraints in terms of these undetermined functions. By introducing new bounded variables as well as a new independent variable and solving the constraints, we are able to apply the theory of dynamical systems to study the properties of the TSS solutions. By finding invariant sets and associated monotonic functions, by applying the LaSalle Invariance Principle and the Monotonicity Principle, by applying the [straight phi] t -connected property of a limit set, and using other theorems, we prove that all of the TSS trajectories are heteroclinic trajectories. In addition, we conduct numerical simulations to confirm and support the qualitative analysis. We obtain all possible types of TSS solutions, by analyzing the qualitative behavior of the original system of ODES from those of the reduced one. We obtain asymptotic expressions for the TSS solutions (e.g., the asymptotic expressions for the metric functions, the source functions and the Ricci scalar). In particular, self-similar flat Friedmann-Robertson-Walker spacetimes are examined in order to obtain insights into the issues related to the null surface in general TSS spacetimes in these coordinates. A discussion of the divergence of the spacetime Ricci scalar and the possible extension of the TSS solutions across the null boundary is presented
Towards time symmetric N-body integration
Dehnen, Walter
2017-11-01
Computational efficiency demands discretized, hierarchically organized and individually adaptive time-step sizes (known as the block-step scheme) for the time integration of N-body models. However, most existing N-body codes adapt individual step sizes in a way that violates time symmetry (and symplecticity), resulting in artificial secular dissipation (and often secular growth of energy errors). Using single-orbit integrations, I investigate various possibilities to reduce or eliminate irreversibility from the time-stepping scheme. Significant improvements over the standard approach are possible at little extra effort. However, in order to reduce irreversible step-size changes to negligible amounts, such as suitable for long-term integrations of planetary systems, more computational effort is needed, while exact time reversibility appears elusive for discretized individual step sizes.
Energy Technology Data Exchange (ETDEWEB)
Bruckman, W.
1986-11-15
The inverse scattering method of Belinsky and Zakharov is used to investigate axially symmetric stationary vacuum soliton solutions in the five-dimensional representation of the Brans-Dicke-Jordan theory of gravitation, where the scalar field of the theory is an element of a five-dimensional metric. The resulting equations for the spacetime metric are similar to those of solitons in general relativity, while the scalar field generated is the product of a simple function of the coordinates and an already known scalar field solution. A family of solutions is considered that reduce, in the absence of rotation, to the five-dimensional form of a well-known Weyl-Levi Civita axially symmetric static vacuum solution. With a suitable choice of parameters, this static limit becomes equivalent to the spherically symmetric solution of the Brans-Dicke theory. An exact metric, in which the Kerr-scalar McIntosh solution is a special case, is given explicitly.
BRAIN TUMOR SEGMENTATION WITH SYMMETRIC TEXTURE AND SYMMETRIC INTENSITY-BASED DECISION FORESTS.
Bianchi, Anthony; Miller, James V; Tan, Ek Tsoon; Montillo, Albert
2013-04-01
Accurate automated segmentation of brain tumors in MR images is challenging due to overlapping tissue intensity distributions and amorphous tumor shape. However, a clinically viable solution providing precise quantification of tumor and edema volume would enable better pre-operative planning, treatment monitoring and drug development. Our contributions are threefold. First, we design efficient gradient and LBPTOP based texture features which improve classification accuracy over standard intensity features. Second, we extend our texture and intensity features to symmetric texture and symmetric intensity which further improve the accuracy for all tissue classes. Third, we demonstrate further accuracy enhancement by extending our long range features from 100mm to a full 200mm. We assess our brain segmentation technique on 20 patients in the BraTS 2012 dataset. Impact from each contribution is measured and the combination of all the features is shown to yield state-of-the-art accuracy and speed.
CANONICAL BACKWARD DIFFERENTIATION SCHEMES FOR ...
African Journals Online (AJOL)
CANONICAL BACKWARD DIFFERENTIATION SCHEMES FOR SOLUTION OF NONLINEAR INITIAL VALUE PROBLEMS OF FIRST ORDER ORDINARY DIFFERENTIAL EQUATIONS. ... Global Journal of Mathematical Sciences ... KEY WORDS: backward differentiation scheme, collocation, initial value problems. Global Jnl ...
Cryptanalysis and improvement of multiparty quantum secret sharing schemes
Energy Technology Data Exchange (ETDEWEB)
Wang Tianyin [State key Laboratory of Networking and Switching Technology, Beijing University of Posts and Telecommunications, Beijing 100876 (China); School of Mathematical Science, Luoyang Normal University, Luoyang 471022 (China)], E-mail: wangtianyin@yahoo.cn; Wen Qiaoyan; Gao Fei; Lin Song [State key Laboratory of Networking and Switching Technology, Beijing University of Posts and Telecommunications, Beijing 100876 (China); Zhu Fuchen [National Laboratory for Modern Communications, PO Box 810, Chengdu 610041 (China)
2008-12-22
A scheme of multiparty quantum secret sharing of classical messages (QSSCM) [Z.J. Zhang et al., Opt. Commun. 269 (2007) 418] was proposed. Lin et al. [S. Lin et al., Opt. Commun. 281 (2008) 4553] showed the last agent can obtain half of the secret in Z.J. Zhang's et al. three-party QSSCM scheme and gave an improved version. We further show the first agent and the last agent can obtain all the secret without introducing any error in Zhang's et al. multiparty QSSCM scheme by a special attack with quantum teleportation. We also present an improved version.
AN ADVANCED LEAKAGE SCHEME FOR NEUTRINO TREATMENT IN ASTROPHYSICAL SIMULATIONS
Energy Technology Data Exchange (ETDEWEB)
Perego, A. [Institut für Kernphysik, Technische Universität Darmstadt, Schlossgartenstraße 2, D-64289 Darmstadt (Germany); Cabezón, R. M. [Physics Department, University of Basel, Klingelbergstrasse 82, CH-4056 Basel (Switzerland); Käppeli, R., E-mail: albino.perego@physik.tu-darmstadt.de [Seminar for Applied Mathematics, ETH Zürich, Rämistrasse 101, 8092 Zürich (Switzerland)
2016-04-15
We present an Advanced Spectral Leakage (ASL) scheme to model neutrinos in the context of core-collapse supernovae (CCSNe) and compact binary mergers. Based on previous gray leakage schemes, the ASL scheme computes the neutrino cooling rates by interpolating local production and diffusion rates (relevant in optically thin and thick regimes, respectively) separately for discretized values of the neutrino energy. Neutrino trapped components are also modeled, based on equilibrium and timescale arguments. The better accuracy achieved by the spectral treatment allows a more reliable computation of neutrino heating rates in optically thin conditions. The scheme has been calibrated and tested against Boltzmann transport in the context of Newtonian spherically symmetric models of CCSNe. ASL shows a very good qualitative and a partial quantitative agreement for key quantities from collapse to a few hundreds of milliseconds after core bounce. We have proved the adaptability and flexibility of our ASL scheme, coupling it to an axisymmetric Eulerian and to a three-dimensional smoothed particle hydrodynamics code to simulate core collapse. Therefore, the neutrino treatment presented here is ideal for large parameter-space explorations, parametric studies, high-resolution tests, code developments, and long-term modeling of asymmetric configurations, where more detailed neutrino treatments are not available or are currently computationally too expensive.
Building Secure Public Key Encryption Scheme from Hidden Field Equations
Directory of Open Access Journals (Sweden)
Yuan Ping
2017-01-01
Full Text Available Multivariate public key cryptography is a set of cryptographic schemes built from the NP-hardness of solving quadratic equations over finite fields, amongst which the hidden field equations (HFE family of schemes remain the most famous. However, the original HFE scheme was insecure, and the follow-up modifications were shown to be still vulnerable to attacks. In this paper, we propose a new variant of the HFE scheme by considering the special equation x2=x defined over the finite field F3 when x=0,1. We observe that the equation can be used to further destroy the special structure of the underlying central map of the HFE scheme. It is shown that the proposed public key encryption scheme is secure against known attacks including the MinRank attack, the algebraic attacks, and the linearization equations attacks. The proposal gains some advantages over the original HFE scheme with respect to the encryption speed and public key size.
Bonus Schemes and Trading Activity
Pikulina, E.S.; Renneboog, L.D.R.; Ter Horst, J.R.; Tobler, P.N.
2013-01-01
Abstract: Little is known about how different bonus schemes affect traders’ propensity to trade and which bonus schemes improve traders’ performance. We study the effects of linear versus threshold (convex) bonus schemes on traders’ behavior. Traders purchase and sell shares in an experimental stock
Bonus schemes and trading activity
Pikulina, E.S.; Renneboog, L.D.R.; ter Horst, J.R.; Tobler, P.N.
2014-01-01
Little is known about how different bonus schemes affect traders' propensity to trade and which bonus schemes improve traders' performance. We study the effects of linear versus threshold bonus schemes on traders' behavior. Traders buy and sell shares in an experimental stock market on the basis of
Transverse Hilbert schemes and completely integrable systems
Directory of Open Access Journals (Sweden)
Donin Niccolò Lora Lamia
2017-12-01
Full Text Available In this paper we consider a special class of completely integrable systems that arise as transverse Hilbert schemes of d points of a complex symplectic surface S projecting onto ℂ via a surjective map p which is a submersion outside a discrete subset of S. We explicitly endow the transverse Hilbert scheme Sp[d] with a symplectic form and an endomorphism A of its tangent space with 2-dimensional eigenspaces and such that its characteristic polynomial is the square of its minimum polynomial and show it has the maximal number of commuting Hamiltonians.We then provide the inverse construction, starting from a 2ddimensional holomorphic integrable system W which has an endomorphism A: TW → TW satisfying the above properties and recover our initial surface S with W ≌ Sp[d].
Optimization of Train Trip Package Operation Scheme
Directory of Open Access Journals (Sweden)
Lu Tong
2015-01-01
Full Text Available Train trip package transportation is an advanced form of railway freight transportation, realized by a specialized train which has fixed stations, fixed time, and fixed path. Train trip package transportation has lots of advantages, such as large volume, long distance, high speed, simple forms of organization, and high margin, so it has become the main way of railway freight transportation. This paper firstly analyzes the related factors of train trip package transportation from its organizational forms and characteristics. Then an optimization model for train trip package transportation is established to provide optimum operation schemes. The proposed model is solved by the genetic algorithm. At last, the paper tests the model on the basis of the data of 8 regions. The results show that the proposed method is feasible for solving operation scheme issues of train trip package.
Geometric multiaxial representation of N -qubit mixed symmetric separable states
SP, Suma; Sirsi, Swarnamala; Hegde, Subramanya; Bharath, Karthik
2017-08-01
The study of N -qubit mixed symmetric separable states is a longstanding challenging problem as no unique separability criterion exists. In this regard, we take up the N -qubit mixed symmetric separable states for a detailed study as these states are of experimental importance and offer an elegant mathematical analysis since the dimension of the Hilbert space is reduced from 2N to N +1 . Since there exists a one-to-one correspondence between the spin-j system and an N -qubit symmetric state, we employ Fano statistical tensor parameters for the parametrization of the spin-density matrix. Further, we use a geometric multiaxial representation (MAR) of the density matrix to characterize the mixed symmetric separable states. Since the separability problem is NP-hard, we choose to study it in the continuum limit where mixed symmetric separable states are characterized by the P -distribution function λ (θ ,ϕ ) . We show that the N -qubit mixed symmetric separable states can be visualized as a uniaxial system if the distribution function is independent of θ and ϕ . We further choose a distribution function to be the most general positive function on a sphere and observe that the statistical tensor parameters characterizing the N -qubit symmetric system are the expansion coefficients of the distribution function. As an example for the discrete case, we investigate the MAR of a uniformly weighted two-qubit mixed symmetric separable state. We also observe that there exists a correspondence between the separability and classicality of states.
Sparse symmetric preconditioners for dense linear systems in electromagnetism
Carpentieri, Bruno; Duff, Iain S.; Giraud, Luc; Monga Made, M. Magolu
2004-01-01
We consider symmetric preconditioning strategies for the iterative solution of dense complex symmetric non-Hermitian systems arising in computational electromagnetics. In particular, we report on the numerical behaviour of the classical incomplete Cholesky factorization as well as some of its recent
Synthesis & Characterization of New bis-Symmetrical Adipoyl ...
African Journals Online (AJOL)
Full Title: Synthesis and Characterization of New bis-Symmetrical Adipoyl, Terepthaloyl, Chiral Diimido-di-L-alanine Diesters and Chiral Phthaloyl-L-alanine Ester of Tripropoxy p-tert-Butyl Calix[4]arene and Study of Their Hosting Ability for Alanine and Na+. Bis-symmetrical tripropoxy p-tert-butyl calix[4]arene esters were ...
Bilateral symmetric autosomal dominant sector chorioretinopathy with late maculopathy
DEFF Research Database (Denmark)
Fledelius, Hans C; Rosenberg, Thomas
2012-01-01
To describe the long-term course of bilateral symmetric autosomal dominant sector chorioretinopathy in a 79-year-old man who was diagnosed at age 31.......To describe the long-term course of bilateral symmetric autosomal dominant sector chorioretinopathy in a 79-year-old man who was diagnosed at age 31....
Axially Symmetric Bianchi Type-I Bulk-Viscous Cosmological ...
Indian Academy of Sciences (India)
Home; Journals; Journal of Astrophysics and Astronomy; Volume 34; Issue 3. Axially Symmetric Bianchi ... The present study deals with spatially homogeneous and anisotropic axially symmetric Bianchi type-I cosmological model with time variable cosmological term in the presence of bulk viscous fluid. The Einstein's field ...
FACES WITH LARGE DIAMETER ON THE SYMMETRICAL TRAVELING SALESMAN POLYTOPE
SIERKSMA, G; TIJSSEN, GA
This paper deals with the symmetric traveling salesman polytope and contains three main theorems. The first one gives a new characterization of (non)adjacency. Based on this characterization a new upper bound for the diameter of the symmetric traveling salesman polytope (conjectured to be 2 by M.
New approach to solve symmetric fully fuzzy linear systems
Indian Academy of Sciences (India)
In this paper, we present a method to solve fully fuzzy linear systems with symmetric coefﬁcient matrix. The symmetric coefﬁcient matrix is decomposed into two systems of equations by using Cholesky method and then a solution can be obtained. Numerical examples are given to illustrate our method.
Entangling capabilities of symmetric two-qubit gates
Indian Academy of Sciences (India)
matrices constitute a 3 × 3 linearly independent, experimentally realizable [4] Cartesian tensor operators which can also provide different symmetric logic gates for quantum pro- cessing tasks. As these two qubit symmetric gates are capable of producing entanglement of quantum states, quantifying their entangling capability ...
Non-symmetrical separated flow along the parabolic wing
Gaifullin, A. M.; Zhvick, V. V.
2017-10-01
Inviscid incompressible separated flow along the parabolic wing is explored. The partition is placed in the symmetry plane. The problem is considered without an assumption of flow symmetry. Self-similar solution is constructed. Both symmetrical and non-symmetrical solutions are observed. Fields of self-similar trajectories and stability are analysed.
On spherically symmetric singularity-free models in relativistic ...
Indian Academy of Sciences (India)
These observations led to the search of spherically symmetric singularity-free cosmo- logical models with a perfect fluid source characterized by isotropic pressure This search resulted in construction of two spherically symmetric singularity-free relativistic cosmo- logical models, describing universes filled with non-adiabatic ...
Symmetric form-invariant dual Pearcey beams.
Ren, Zhijun; Fan, Changjiang; Shi, Yile; Chen, Bo
2016-08-01
We introduce another type of Pearcey beam, namely, dual Pearcey (DP) beams, based on the Pearcey function of catastrophe theory. DP beams are experimentally generated by applying Fresnel diffraction of bright elliptic rings. Form-invariant Bessel distribution beams can be regarded as a special case of DP beams. Subsequently, the basic propagation characteristics of DP beams are identified. DP beams are the result of the interference of two half DP beams instead of two classical Pearcey beams. Moreover, we also verified that half DP beams (including special-case parabolic-like beams) generated by half elliptical rings (circular rings) are a new member of the family of form-invariant beams.
Symmetric metamaterials based on flower-shaped structure
Energy Technology Data Exchange (ETDEWEB)
Tuong, P.V. [Department of Physics, Quantum Photonic Science Research Center and Research Institute for Nature Sciences, Hanyang University, Seoul 133-791 (Korea, Republic of); Institute of Material Sciences, Vietnam Academy of Science and Technology, Hanoi (Viet Nam); Park, J.W. [Department of Physics, Quantum Photonic Science Research Center and Research Institute for Nature Sciences, Hanyang University, Seoul 133-791 (Korea, Republic of); Rhee, J.Y. [Sungkyunkwan University, Suwon (Korea, Republic of); Kim, K.W. [Sunmoon University, Asan (Korea, Republic of); Cheong, H. [Sogang University, Seoul (Korea, Republic of); Jang, W.H. [Electromagnetic Wave Institute, Korea Radio Promotion Association, Seoul (Korea, Republic of); Lee, Y.P., E-mail: yplee@hanyang.ac.kr [Department of Physics, Quantum Photonic Science Research Center and Research Institute for Nature Sciences, Hanyang University, Seoul 133-791 (Korea, Republic of)
2013-08-15
We proposed new models of metamaterials (MMs) based on a flower-shaped structure (FSS), whose “meta-atoms” consist of two flower-shaped metallic parts separated by a dielectric layer. Like the non-symmetric MMs based on cut-wire-pairs or electric ring resonators, the symmetrical FSS demonstrates the negative permeability at GHz frequencies. Employing the results, we designed a symmetric negative-refractive-index MM [a symmetric combined structure (SCS)], which is composed of FSSs and cross continuous wires. The MM properties of the FSS and the SCS are presented numerically and experimentally. - Highlights: • A new designed of sub-wavelength metamaterial, flower-shaped structure was proposed. • Flower-shaped meta-atom illustrated effective negative permeability. • Based on the meta-atom, negative refractive index was conventionally gained. • Negative refractive index was demonstrated with symmetric properties for electromagnetic wave. • Dimensional parameters were studied under normal electromagnetic wave.
Topological states in partially-PT-symmetric azimuthal potentials
Kartashov, Yaroslav V; Torner, Lluis
2015-01-01
We introduce partially-parity-time-symmetric (pPT-symmetric) azimuthal potentials composed from individual PT-symmetric cells located on a ring, where two azimuthal directions are nonequivalent in a sense that in such potentials excitations carrying topological dislo-cations exhibit different dynamics for different directions of energy circulation in the initial field distribution. Such non-conservative ratchet-like structures support rich families of stable vortex solitons in cubic nonlinear media, whose properties depend on the sign of the topological charge due to the nonequivalence of azimuthal directions. In contrast, oppositely charged vortex solitons remain equivalent in similar fully PT-symmetric potentials. The vortex solitons in the pPT- and PT-symmetric potentials are shown to feature qualitatively different internal current distributions, which are described by different discrete rotation symmetries of the intensity profiles.
Energy Technology Data Exchange (ETDEWEB)
Akbar, M.M., E-mail: akbar@utdallas.edu
2017-06-10
It is well known that static spherically symmetric spacetimes can admit foliations by flat spacelike hypersurfaces, which are best described in terms of the Painlevè–Gullstrand coordinates. The uniqueness and existence of such foliations were addressed earlier. In this paper, we prove, purely geometrically, that any possible foliation of a static spherically symmetric spacetime by an arbitrary codimension-one spherical spacelike geometry, up to time translation and rotation, is unique, and we find the algebraic condition under which it exists. This leads us to what can be considered as the most natural generalization of the Painlevè–Gullstrand coordinate system for static spherically symmetric metrics, which, in turn, makes it easy to derive generic conclusions on foliation and to study specific cases as well as to easily reproduce previously obtained generalizations as special cases. In particular, we note that the existence of foliation by flat hypersurfaces guarantees the existence of foliation by hypersurfaces whose Ricci curvature tensor is everywhere non-positive (constant negative curvature is a special case). The study of uniqueness and the existence concurrently solves the question of embeddability of a spherical spacelike geometry in one-dimensional higher static spherically symmetric spacetimes, and this produces known and new results geometrically, without having to go through the momentum and Hamiltonian constraints.
Directory of Open Access Journals (Sweden)
M.M. Akbar
2017-06-01
Full Text Available It is well known that static spherically symmetric spacetimes can admit foliations by flat spacelike hypersurfaces, which are best described in terms of the Painlevè–Gullstrand coordinates. The uniqueness and existence of such foliations were addressed earlier. In this paper, we prove, purely geometrically, that any possible foliation of a static spherically symmetric spacetime by an arbitrary codimension-one spherical spacelike geometry, up to time translation and rotation, is unique, and we find the algebraic condition under which it exists. This leads us to what can be considered as the most natural generalization of the Painlevè–Gullstrand coordinate system for static spherically symmetric metrics, which, in turn, makes it easy to derive generic conclusions on foliation and to study specific cases as well as to easily reproduce previously obtained generalizations as special cases. In particular, we note that the existence of foliation by flat hypersurfaces guarantees the existence of foliation by hypersurfaces whose Ricci curvature tensor is everywhere non-positive (constant negative curvature is a special case. The study of uniqueness and the existence concurrently solves the question of embeddability of a spherical spacelike geometry in one-dimensional higher static spherically symmetric spacetimes, and this produces known and new results geometrically, without having to go through the momentum and Hamiltonian constraints.
Statistical physics of the symmetric group
Williams, Mobolaji
2017-04-01
Ordered chains (such as chains of amino acids) are ubiquitous in biological cells, and these chains perform specific functions contingent on the sequence of their components. Using the existence and general properties of such sequences as a theoretical motivation, we study the statistical physics of systems whose state space is defined by the possible permutations of an ordered list, i.e., the symmetric group, and whose energy is a function of how certain permutations deviate from some chosen correct ordering. Such a nonfactorizable state space is quite different from the state spaces typically considered in statistical physics systems and consequently has novel behavior in systems with interacting and even noninteracting Hamiltonians. Various parameter choices of a mean-field model reveal the system to contain five different physical regimes defined by two transition temperatures, a triple point, and a quadruple point. Finally, we conclude by discussing how the general analysis can be extended to state spaces with more complex combinatorial properties and to other standard questions of statistical mechanics models.
Symmetrical collision of multiple vortex rings
Hernández, R. H.; Reyes, T.
2017-10-01
In this work, we investigate the motion, interaction, and simultaneous collision between many initially stable vortex rings arranged symmetrically in two initial configurations, three and six rings making an angle of 60 and 120° between their straight path lines, respectively. We report results for laminar vortex rings in air obtained through numerical simulations of the ring velocity, pressure, and vorticity fields, both in free flight and during the entire collision. Each collision was studied for small Reynolds numbers R e formed by laterally expanding dipolar arms with top and bottom secondary vortex rings. The case of six colliding rings produces, as secondary structures, two big rings moving in opposite directions, a process that reminds us of the head-on collision of two rings [T. T. Lim and T. B. Nickels, "Instability and reconnection in the head-on collision of two vortex rings," Nature 357, 225-227 (1992)] under a hypothetical time reversal transformation. Both collisions display a characteristic kinetic energy evolution where mean collision stages can be identified within the range of Reynolds numbers investigated here.
Triple symmetric key cryptosystem for data security
Fuzail, C. Md; Norman, Jasmine; Mangayarkarasi, R.
2017-11-01
As the technology is getting spreads in the macro seconds of speed and in which the trend changing era from human to robotics the security issue is also getting increased. By means of using machine attacks it is very easy to break the cryptosystems in very less amount of time. Cryptosystem is a process which provides the security in all sorts of processes, communications and transactions to be done securely with the help of electronical mechanisms. Data is one such thing with the expanded implication and possible scraps over the collection of data to secure predominance and achievement, Information Security is the process where the information is protected from invalid and unverified accessibilities and data from mishandling. So the idea of Information Security has risen. Symmetric key which is also known as private key.Whereas the private key is mostly used to attain the confidentiality of data. It is a dynamic topic which can be implemented over different applications like android, wireless censor networks, etc. In this paper, a new mathematical manipulation algorithm along with Tea cryptosystem has been implemented and it can be used for the purpose of cryptography. The algorithm which we proposed is straightforward and more powerful and it will authenticate in harder way and also it will be very difficult to break by someone without knowing in depth about its internal mechanisms.
PT-symmetric quantum state discrimination.
Bender, Carl M; Brody, Dorje C; Caldeira, João; Günther, Uwe; Meister, Bernhard K; Samsonov, Boris F
2013-04-28
The objective of this paper is to explain and elucidate the formalism of PT quantum mechanics by applying it to a well-known problem in conventional Hermitian quantum mechanics, namely the problem of state discrimination. Suppose that a system is known to be in one of two quantum states, |ψ(1)> or |ψ(2)>. If these states are not orthogonal, then the requirement of unitarity forbids the possibility of discriminating between these two states with one measurement; that is, determining with one measurement what state the system is in. In conventional quantum mechanics, there is a strategy in which successful state discrimination can be achieved with a single measurement but only with a success probability p that is less than unity. In this paper, the state-discrimination problem is examined in the context of PT quantum mechanics and the approach is based on the fact that a non-Hermitian PT-symmetric Hamiltonian determines the inner product that is appropriate for the Hilbert space of physical states. It is shown that it is always possible to choose this inner product so that the two states |ψ(1)> and |ψ(2)> are orthogonal. Using PT quantum mechanics, one cannot achieve a better state discrimination than in ordinary quantum mechanics, but one can instead perform a simulated quantum state discrimination, in which with a single measurement a perfect state discrimination is realized with probability p.
A note on a one-parameter family of non-symmetric number triangles
Directory of Open Access Journals (Sweden)
Maria Irene Falcão
2012-01-01
Full Text Available The recent growing interest in special Clifford algebra valued polynomial solutions of generalized Cauchy-Riemann systems in \\((n + 1\\-dimensional Euclidean spaces suggested a detailed study of the arithmetical properties of their coefficients, due to their combinatoric relevance. This concerns, in particular, a generalized Appell sequence of homogeneous polynomials whose coefficient set can be treated as a one-parameter family of non-symmetric triangles of fractions. The discussion of its properties, similar to those of the ordinary Pascal triangle (which itself does not belong to the family, is carried out in this paper.
Plane Symmetric Viscous Fluid Cosmological Models with Varying Λ-Term
Pradhan, Anirudh; Pandey, Purnima; Jotania, Kanti; Yadav, Mahesh Kumar
2007-11-01
Plane symmetric viscous fluid cosmological models of the universe with a variable cosmological term are investigated. The viscosity coefficient of bulk viscous fluid is assumed to be a power function of mass density whereas the coefficient of shear viscosity is to be proportional to rate of expansion in the model. We have also obtained a special model in which the shear viscosity is assumed to be zero. The cosmological constant Λ is found to be a decreasing function of time and a positive which is supported by results from recent supernovae Ia observations. Some physical and geometric properties of the models are also discussed.
Translationally symmetric extended MHD via Hamiltonian reduction: Energy-Casimir equilibria
Kaltsas, D. A.; Throumoulopoulos, G. N.; Morrison, P. J.
2017-09-01
The Hamiltonian structure of ideal translationally symmetric extended MHD (XMHD) is obtained by employing a method of Hamiltonian reduction on the three-dimensional noncanonical Poisson bracket of XMHD. The existence of the continuous spatial translation symmetry allows the introduction of Clebsch-like forms for the magnetic and velocity fields. Upon employing the chain rule for functional derivatives, the 3D Poisson bracket is reduced to its symmetric counterpart. The sets of symmetric Hall, Inertial, and extended MHD Casimir invariants are identified, and used to obtain energy-Casimir variational principles for generalized XMHD equilibrium equations with arbitrary macroscopic flows. The obtained set of generalized equations is cast into Grad-Shafranov-Bernoulli (GSB) type, and special cases are investigated: static plasmas, equilibria with longitudinal flows only, and Hall MHD equilibria, where the electron inertia is neglected. The barotropic Hall MHD equilibrium equations are derived as a limiting case of the XMHD GSB system, and a numerically computed equilibrium configuration is presented that shows the separation of ion-flow from electro-magnetic surfaces.
Federal Laboratory Consortium — Supporting Navy special weapons, the division provides an array of engineering services, technical publication support services, logistics support services, safety...
Comparison of eigensolvers for symmetric band matrices.
Moldaschl, Michael; Gansterer, Wilfried N
2014-09-15
We compare different algorithms for computing eigenvalues and eigenvectors of a symmetric band matrix across a wide range of synthetic test problems. Of particular interest is a comparison of state-of-the-art tridiagonalization-based methods as implemented in Lapack or Plasma on the one hand, and the block divide-and-conquer (BD&C) algorithm as well as the block twisted factorization (BTF) method on the other hand. The BD&C algorithm does not require tridiagonalization of the original band matrix at all, and the current version of the BTF method tridiagonalizes the original band matrix only for computing the eigenvalues. Avoiding the tridiagonalization process sidesteps the cost of backtransformation of the eigenvectors. Beyond that, we discovered another disadvantage of the backtransformation process for band matrices: In several scenarios, a lot of gradual underflow is observed in the (optional) accumulation of the transformation matrix and in the (obligatory) backtransformation step. According to the IEEE 754 standard for floating-point arithmetic, this implies many operations with subnormal (denormalized) numbers, which causes severe slowdowns compared to the other algorithms without backtransformation of the eigenvectors. We illustrate that in these cases the performance of existing methods from Lapack and Plasma reaches a competitive level only if subnormal numbers are disabled (and thus the IEEE standard is violated). Overall, our performance studies illustrate that if the problem size is large enough relative to the bandwidth, BD&C tends to achieve the highest performance of all methods if the spectrum to be computed is clustered. For test problems with well separated eigenvalues, the BTF method tends to become the fastest algorithm with growing problem size.
Dynamic properties of symmetric optothermal microactuator
You, Q. Y.; Zhang, H. J.; Wang, Y. D.; Chen, J. J.
2017-10-01
This paper proposes a method of a symmetric optothermal microactuator (S-OTMA) directly driven by laser pulse. Based on the principle of thermal flux, a dynamic model is established describing the laser-induced optothermal temperature rise and optothermal expansion of the S-OTMA’s expansion arm. The dynamic optothermal expansion and the relationship between the expansion amplitude and laser pulse frequency are simulated, indicating that the expansion arm expands and reverts periodically with the same frequency of the laser pulse, and that the expansion amplitude decreases with the increase of laser pulse frequency. Experiments have been further conducted on a micro-fabricated S-OTMA under a laser pulse of 3.3 mW power and 2-18 Hz frequency. It is shown that the S-OTMA can periodically deflect in accordance with the same frequency of the laser pulse, with a maximum response frequency of at least 18 Hz. The maximum deflection (vibration) amplitude is measured to be 13.7 µm (at 2 Hz), and the amplitude decreases as the frequency increases. Both the theoretical model and experiments prove that the S-OTMA is capable of implementing direct laser-controlled microactuation in which only ~3 mW laser power is demanded. Furthermore, bi-directional actuation of the optothermal microactuator (such as S-OTMA) can be easily achieved by alternately irradiating either arm of the microactuator. This work may broaden the applications of the S-OTMA, as well as optothermal microactuators in MEMS/MOEMS and micro/nano-technology.
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.
Small-scale classification schemes
DEFF Research Database (Denmark)
Hertzum, Morten
2004-01-01
Small-scale classification schemes are used extensively in the coordination of cooperative work. This study investigates the creation and use of a classification scheme for handling the system requirements during the redevelopment of a nation-wide information system. This requirements classificat....... This difference between the written requirements specification and the oral discussions at the meetings may help explain software engineers general preference for people, rather than documents, as their information sources.......Small-scale classification schemes are used extensively in the coordination of cooperative work. This study investigates the creation and use of a classification scheme for handling the system requirements during the redevelopment of a nation-wide information system. This requirements....... While coordination mechanisms focus on how classification schemes enable cooperation among people pursuing a common goal, boundary objects embrace the implicit consequences of classification schemes in situations involving conflicting goals. Moreover, the requirements specification focused on functional...
Honohan, Patrick
1987-01-01
A Ponzi scheme is an arrangement whereby a promoter offers an investment opportunity with attractive dividends, but where the only basis for the dividends is the future receipts from new investors. The first of these two notes explores some of the analytical properties of a Ponzi scheme, addressing in particular the question whether it is possible for a Ponzi scheme to exist if all the participants are rational. The second note briefly examines the collapse of the PMPA insurance company whos...
Casadevall, Arturo; Fang, Ferric C
2014-04-01
As the body of scientific knowledge in a discipline increases, there is pressure for specialization. Fields spawn subfields that then become entities in themselves that promote further specialization. The process by which scientists join specialized groups has remarkable similarities to the guild system of the middle ages. The advantages of specialization of science include efficiency, the establishment of normative standards, and the potential for greater rigor in experimental research. However, specialization also carries risks of monopoly, monotony, and isolation. The current tendency to judge scientific work by the impact factor of the journal in which it is published may have roots in overspecialization, as scientists are less able to critically evaluate work outside their field than before. Scientists in particular define themselves through group identity and adopt practices that conform to the expectations and dynamics of such groups. As part of our continuing analysis of issues confronting contemporary science, we analyze the emergence and consequences of specialization in science, with a particular emphasis on microbiology, a field highly vulnerable to balkanization along microbial phylogenetic boundaries, and suggest that specialization carries significant costs. We propose measures to mitigate the detrimental effects of scientific specialism.
Remarks on quantum duopoly schemes
Fraçkiewicz, Piotr
2016-01-01
The aim of this paper is to discuss in some detail the two different quantum schemes for duopoly problems. We investigate under what conditions one of the schemes is more reasonable than the other one. Using the Cournot's duopoly example, we show that the current quantum schemes require a slight refinement so that they output the classical game in a particular case. Then, we show how the amendment changes the way of studying the quantum games with respect to Nash equilibria. Finally, we define another scheme for the Cournot's duopoly in terms of quantum computation.
DEFF Research Database (Denmark)
Rotbart, Noy Galil
times, effectively eliminating the second penalty mentioned. We continue this theoretical study in several ways. First, we dedicate a large part of the thesis to the graph family of trees, for which we provide an overview of labeling schemes supporting several important functions such as ancestry......, routing and especially adjacency. The survey is complemented by novel contributions to this study, among which are the first asymptotically optimal adjacency labeling scheme for bounded degree trees, improved bounds on ancestry labeling schemes, dynamic multifunctional labeling schemes and an experimental...
DEFF Research Database (Denmark)
Mousten, Birthe; Laursen, Anne Lise
2016-01-01
Across different fields of research, one feature is often overlooked: the use of language for specialized purposes (LSP) as a cross-discipline. Mastering cross-disciplinarity is the precondition for communicating detailed results within any field. Researchers in specialized languages work cross......-disciplinarily, because they work with both derivative and contributory approaches. Derivative, because specialized language retrieves its philosophy of science as well as methods from both the natural sciences, social sciences and humanistic sciences. Contributory because language results support the communication...... science fields communicate their findings. With this article, we want to create awareness of the work in this special area of language studies and of the inherent cross-disciplinarity that makes LSP special compared to common-core language. An acknowledgement of the importance of this field both in terms...
Foundations of Grothendieck duality for diagrams of schemes
Lipman, Joseph
2009-01-01
The first part written by Joseph Lipman, accessible to mid-level graduate students, is a full exposition of the abstract foundations of Grothendieck duality theory for schemes (twisted inverse image, tor-independent base change,...), in part without noetherian hypotheses, and with some refinements for maps of finite tor-dimension. The ground is prepared by a lengthy treatment of the rich formalism of relations among the derived functors, for unbounded complexes over ringed spaces, of the sheaf functors tensor, hom, direct and inverse image. Included are enhancements, for quasi-compact quasi-separated schemes, of classical results such as the projection and Künneth isomorphisms. In the second part, written independently by Mitsuyasu Hashimoto, the theory is extended to the context of diagrams of schemes. This includes, as a special case, an equivariant theory for schemes with group actions. In particular, after various basic operations on sheaves such as (derived) direct images and inverse images are set up, ...
PT -symmetric dimer of coupled nonlinear oscillators
Indian Academy of Sciences (India)
Note that there are two special cases (i.e. when q = −1, −1/3) when A2 only satisfies quadratic equation. 5.5 A novel exact solution of the RWA equations. In addition to the solutions just discussed, the coupled eqs (69) and (70) also have a novel exact solution φ1 = e(γ /2)t−(ia/γ ) sinh(γ t+φ)−ibt , φ2 = e−(γ /2)t−(ia/γ ) sinh(γ ...
Flow-separation patterns on symmetric forebodies
Keener, Earl R.
1986-01-01
Flow-visualization studies of ogival, parabolic, and conical forebodies were made in a comprehensive investigation of the various types of flow patterns. Schlieren, vapor-screen, oil-flow, and sublimation flow-visualization tests were conducted over an angle-of-attack range from 0 deg. to 88 deg., over a Reynolds-number range from 0.3X10(6) to 2.0X10(6) (based on base diameter), and over a Mach number range from 0.1 to 2. The principal effects of angle of attack, Reynolds number, and Mach number on the occurrence of vortices, the position of vortex shedding, the principal surface-flow-separation patterns, the magnitude of surface-flow angles, and the extent of laminar and turbulent flow for symmetric, asymmetric, and wake-like flow-separation regimes are presented. It was found that the two-dimensional cylinder analogy was helpful in a qualitative sense in analyzing both the surface-flow patterns and the external flow field. The oil-flow studies showed three types of primary separation patterns at the higher Reynolds numbers owing to the influence of boundary-layer transition. The effect of angle of attack and Reynolds number is to change the axial location of the onset and extent of the primary transitional and turbulent separation regions. Crossflow inflectional-instability vortices were observed on the windward surface at angles of attack from 5 deg. to 55 deg. Their effect is to promote early transition. At low angles of attack, near 10 deg., an unexpected laminar-separation bubble occurs over the forward half of the forebody. At high angles of attack, at which vortex asymmetry occurs, the results support the proposition that the principal cause of vortex asymmetry is the hydrodynamic instability of the inviscid flow field. On the other hand, boundary-layer asymmetries also occur, especially at transitional Reynolds numbers. The position of asymmetric vortex shedding moves forward with increasing angle of attack and with increasing Reynolds number, and moves
Symmetric-Galerkin BEM simulation of fracture with frictional contact
CSIR Research Space (South Africa)
Phan, AV
2003-06-14
Full Text Available A symmetric-Galerkin boundary element framework for fracture analysis with frictional contact (crack friction) on the crack surfaces is presented. The algorithm employs a continuous interpolation on the crack surface (utilizing quadratic boundary...
Optical solitons in periodically managed PT-symmetric media
Abdullaev, F. Kh.; Galimzyanov, R. M.
2018-03-01
The dynamics of light beams in the nonlinear optical media with periodically modulated in the longitudinal direction parity-time distribution of the complex refractive index is investigated. The possibility of dynamical stabilization of PT-symmetric solitons is demonstrated.
Characteristics of a typical lifting symmetric supercritical airfoil
Ramaswamy, MA
1987-01-01
The theoretical aerodynamic characteristics of a typical lifting symmetric supercritical airfoil demonstrating its superiority over thenaca 0012 airfoil from which it was derived are presented in this paper. Further, limited experimental results confirming the theoretical inference are also presented.
Synthesis of symmetrical systems of discrete power functions
Directory of Open Access Journals (Sweden)
А. Я. Білецький
2003-03-01
Full Text Available The procedure of building up symmetrical matrixes, which form systems of basis digital power functions, is worked out and some peculiarities of using them for the spectral analysis of signals are discussed
Systems of Differential Equations with Skew-Symmetric, Orthogonal Matrices
Glaister, P.
2008-01-01
The solution of a system of linear, inhomogeneous differential equations is discussed. The particular class considered is where the coefficient matrix is skew-symmetric and orthogonal, and where the forcing terms are sinusoidal. More general matrices are also considered.
Estimation of Time Varying Autoregressive Symmetric Alpha Stable
National Aeronautics and Space Administration — In this work, we present a novel method for modeling time-varying autoregressive impulsive signals driven by symmetric alpha stable distributions. The proposed...
Estimation of Time-Varying Autoregressive Symmetric Alpha Stable
National Aeronautics and Space Administration — In the last decade alpha-stable distributions have become a standard model for impulsive data. Especially the linear symmetric alpha-stable processes have found...
Quantum Symmetric Cooperative Game with a Harmonious Coalition
Elgazzar, A. S.; Elrayes, H. A.
2017-12-01
The concept of forming harmonious coalitions is introduced to both classical and quantum symmetric cooperative games. In both the cases, players are motivated to form coalitions. Also, the main feature of the cooperative game is conserved.
Symmetrization of mathematical model of charge transport in semiconductors
Directory of Open Access Journals (Sweden)
Alexander M. Blokhin
2002-11-01
Full Text Available A mathematical model of charge transport in semiconductors is considered. The model is a quasilinear system of differential equations. A problem of finding an additional entropy conservation law and system symmetrization are solved.
Effect of dividing daylight in symmetric prismatic daylight collector
Yeh, Shih-Chuan; Lu, Ju-Lin; Cheng, Yu-Chin
2017-04-01
This paper presented a symmetric prismatic daylight collector to collect daylight for the natural light illumination system. We analyzed the characteristics of the emerging light when the parallel light beam illuminate on the horizontally placed symmetric prismatic daylight collector. The ratio of the relative intensities of collected daylight that emerging from each surface of the daylight collector shown that the ratio is varied with the incident angle during a day. The simulation of the emerging light of the daylight collector shown that the ratio of emerging light is varied with the tilted angle when sunshine illuminated on a symmetric prismatic daylight collector which was not placed horizontally. The integration of normalized intensity is also varied with the tilted angle. The symmetric prismatic daylight collector with the benefits of reducing glare and dividing intensity of incident daylight, it is applicable to using in the natural light illumination system and hybrid system for improving the efficiency of utilizing of solar energy.
Use of Symmetrical Number Systems in Electronic Warfare
2013-12-01
undersampling techniques based on co- prime sampling rates and symmetrical number systems have been introduced. Symmetrical 1 number systems based on coprime...well–known (and easily derivable by using the prime number theorem [69]) that PN# = exp[(1+o(1))n logn]. Assume N ≥ 6. It is immediate that PN#> (N +1...plotted against the values of M̂RSNS, and the data points were curve fitted to a quadratic polynomial using MATLAB’s curve fitting toolbox, resulting in
Stochastic thermodynamics for Ising chain and symmetric exclusion process.
Toral, R; Van den Broeck, C; Escaff, D; Lindenberg, Katja
2017-03-01
We verify the finite-time fluctuation theorem for a linear Ising chain in contact with heat reservoirs at its ends. Analytic results are derived for a chain consisting of two spins. The system can be mapped onto a model for particle transport, namely, the symmetric exclusion process in contact with thermal and particle reservoirs. We modify the symmetric exclusion process to represent a thermal engine and reproduce universal features of the efficiency at maximum power.
Horizon Quantum Mechanics: spherically symmetric and rotating sources
Giusti, Andrea
2017-12-01
In this paper we discuss some mathematical aspects of the horizon wave-function formalism, also known in the literature as horizon quantum mechanics. In particular, first we review the structure of both the global and local formalism for static spherically symmetric sources. Then, we present an extension of the global analysis for rotating black holes and we also point out some technical diffculties that arise while attempting the local analysis for non-spherically symmetric sources.
NEW SYMMETRIC ENCRYPTION SYSTEM BASED ON EVOLUTIONARY ALGORITHM
A. Mouloudi
2015-01-01
In this article, we present a new symmetric encryption system which is a combination of our ciphering evolutionary system SEC [1] and a new ciphering method called “fragmentation”. This latter allows the alteration of the appearance frequencies of characters from a given text. Our system has at its disposed two keys, the first one is generated by the evolutionary algorithm, the second one is generated after “fragmentation” part. Both of them are symmetric, session keys and strengt...
Baum, Brian; Dionne, Jennifer; Alaeian, Hadiseh; Jankovic, Vladan; Lawrence, Mark
2016-09-01
Metasurfaces offer exotic optical properties, which often originate from carefully designed material geometries. With locked geometries, these metasurfaces are difficult or impossible to change post-fabrication. Here, we theoretically explore a nano-scale coaxial structure capable of adjustably manipulating the polarization, phase, and spatial distribution of light through the introduction of parity-time (PT) symmetric perturbations. Coaxial waveguides possess degenerate modes, corresponding to different orbital angular momentum (OAM) states. The degeneracy of OAM modes can be lifted through the introduction of any non-zero amount of gain and loss into the structure in a way that matches the azimuthal periodicity of the degenerate mode pair. New hybrid complex conjugate modes are created which lose their pure OAM nature and are either amplifying or lossy. We confirm this behavior using both a Hamiltonian formulation and degenerate perturbation theory, and propose this selective excitation and absorption scheme as a new method of filtering for mode division multiplexing in on-chip nanophotonic systems. In addition to the creation of new hybrid modes, we show that these PT-symmetric perturbations in coaxial apertures are capable of converting incident circularly polarized light into linearly polarized light with unity efficiency. Further, due to the localization of field intensity within the gain sections, it is possible to rotate linear polarization and induce up to a pi-phase shift. We describe how our PT-symmetric coaxial aperture could function as a reconfigurable meta-atom for phase, amplitude, and polarization controlled meta-surfaces, and discuss routes toward unity-efficiency, reconfigurable holography.
Finite size effects in the averaged eigenvalue density of Wigner random-sign real symmetric matrices
Dhesi, G. S.; Ausloos, M.
2016-06-01
Nowadays, strict finite size effects must be taken into account in condensed matter problems when treated through models based on lattices or graphs. On the other hand, the cases of directed bonds or links are known to be highly relevant in topics ranging from ferroelectrics to quotation networks. Combining these two points leads us to examine finite size random matrices. To obtain basic materials properties, the Green's function associated with the matrix has to be calculated. To obtain the first finite size correction, a perturbative scheme is hereby developed within the framework of the replica method. The averaged eigenvalue spectrum and the corresponding Green's function of Wigner random sign real symmetric N ×N matrices to order 1 /N are finally obtained analytically. Related simulation results are also presented. The agreement is excellent between the analytical formulas and finite size matrix numerical diagonalization results, confirming the correctness of the first-order finite size expression.
A stationary cylindrically symmetric spacetime which admits CTCs and its physical interpretation
Ahmed, Faizuddin
2017-11-01
Here we present a stationary cylindrically symmetric spacetime which is free from curvature divergence, and satisfy pure radiation field as matter-energy content with positive constant energy density. The metric admits circular closed timelike curves (CTCs) everywhere outside a finite region and the stability of these curves under small linear perturbations is studied, and found to be linearly stable. The metric is of type N in the Petrov classification scheme, and it has a shearfree geodesic null congruence. The physical interpretation of this solution, based on the study of the equation of the geodesic deviation, will be presented. It is demonstrated that, this solution can be understood as exact transverse gravitational waves with amplitudes Ψ4.
Two-point motional Stark effect diagnostic for Madison Symmetric Torus
Energy Technology Data Exchange (ETDEWEB)
Ko, J.; Den Hartog, D. J.; Caspary, K. J.; Den Hartog, E. A. [University of Wisconsin-Madison, Madison, Wisconsin 53706 (United States); Pablant, N. A. [University of California-San Diego, La Jolla, California 92093 (United States); Summers, H. P. [University of Strathclyde, Glasgow G1 1XQ, Scotland (United Kingdom)
2010-10-15
A high-precision spectral motional Stark effect (MSE) diagnostic provides internal magnetic field measurements for Madison Symmetric Torus (MST) plasmas. Currently, MST uses two spatial views - on the magnetic axis and on the midminor (off-axis) radius, the latter added recently. A new analysis scheme has been developed to infer both the pitch angle and the magnitude of the magnetic field from MSE spectra. Systematic errors are reduced by using atomic data from atomic data and analysis structure in the fit. Reconstructed current density and safety factor profiles are more strongly and globally constrained with the addition of the off-axis radius measurement than with the on-axis one only.
Modeling of I-V characteristics in symmetric double-gate polysilicon thin-film transistors
Directory of Open Access Journals (Sweden)
Xiaoyu Ma
2017-06-01
Full Text Available A new closed-form approximation for surface potential and drain current (DC in symmetric double-gate polysilicon thin-film transistors (DG poly-Si TFTs is proposed. The solution of the surface potential is single-piece and suitable for a wide range of gate voltages under different conditions. A comparison with numerical results shows that this scheme gives an accurate description of surface potential. The development of surface-potential-based compact model for I-V characteristics is achieved based on this calculation. Finally, the validity of the model is verified by comparisons with various experimental data. It is showing that the model is accurate over a wide range of operation regions.
Solutions for the conductivity of multi-coated spheres and spherically symmetric inclusion problems
Pham, Duc Chinh
2018-02-01
Variational results on the macroscopic conductivity (thermal, electrical, etc.) of the multi-coated sphere assemblage have been used to derive the explicit expression of the respective field (thermal, electrical, etc.) within the spheres in d dimensions (d=2,3). A differential substitution approach has been developed to construct various explicit expressions or determining equations for the effective spherically symmetric inclusion problems, which include those with radially variable conductivity, different radially variable transverse and normal conductivities, and those involving imperfect interfaces, in d dimensions. When the volume proportion of the outermost spherical shell increases toward 1, one obtains the respective exact results for the most important specific cases: the dilute solutions for the compound inhomogeneities suspended in a major matrix phase. Those dilute solution results are also needed for other effective medium approximation schemes.
Deng, C B; Brower, D L
2010-10-01
The multichannel interferometer system on the helically symmetric experiment (HSX) stellarator is reconfigured to perform far-forward collective scattering measurements of electron density fluctuations. The collective scattering system has nine viewing chords with 1.5 cm spacing. Scattered power is measured using a homodyne detection scheme. Far-forward collective scattering provides a line-integrated measurement of fluctuations within the divergence of the probe beam covering wavenumber range: k(⊥)<2 cm(-1). The perpendicular wavenumber consists of poloidal and radial contributions that vary with chord position. Both coherent modes and broadband fluctuation are measured. When HSX is operated without quasihelical symmetry at B(T)=1 T and n(e)∼4×10(12) cm(-3), a coherent electrostatic fluctuation is observed.
Deep learning of symmetrical discrepancies for computer-aided detection of mammographic masses
Kooi, Thijs; Karssemeijer, Nico
2017-03-01
When humans identify objects in images, context is an important cue; a cheetah is more likely to be a domestic cat when a television set is recognised in the background. Similar principles apply to the analysis of medical images. The detection of diseases that manifest unilaterally in symmetrical organs or organ pairs can in part be facilitated by a search for symmetrical discrepancies in or between the organs in question. During a mammographic exam, images are recorded of each breast and absence of a certain structure around the same location in the contralateral image will render the area under scrutiny more suspicious and conversely, the presence of similar tissue less so. In this paper, we present a fusion scheme for a deep Convolutional Neural Network (CNN) architecture with the goal to optimally capture such asymmetries. The method is applied to the domain of mammography CAD, but can be relevant to other medical image analysis tasks where symmetry is important such as lung, prostate or brain images.
Symmetric Kullback-Leibler Metric Based Tracking Behaviors for Bioinspired Robotic Eyes
Directory of Open Access Journals (Sweden)
Hengli Liu
2015-01-01
Full Text Available A symmetric Kullback-Leibler metric based tracking system, capable of tracking moving targets, is presented for a bionic spherical parallel mechanism to minimize a tracking error function to simulate smooth pursuit of human eyes. More specifically, we propose a real-time moving target tracking algorithm which utilizes spatial histograms taking into account symmetric Kullback-Leibler metric. In the proposed algorithm, the key spatial histograms are extracted and taken into particle filtering framework. Once the target is identified, an image-based control scheme is implemented to drive bionic spherical parallel mechanism such that the identified target is to be tracked at the center of the captured images. Meanwhile, the robot motion information is fed forward to develop an adaptive smooth tracking controller inspired by the Vestibuloocular Reflex mechanism. The proposed tracking system is designed to make the robot track dynamic objects when the robot travels through transmittable terrains, especially bumpy environment. To perform bumpy-resist capability under the condition of violent attitude variation when the robot works in the bumpy environment mentioned, experimental results demonstrate the effectiveness and robustness of our bioinspired tracking system using bionic spherical parallel mechanism inspired by head-eye coordination.
Symmetric Kullback-Leibler Metric Based Tracking Behaviors for Bioinspired Robotic Eyes.
Liu, Hengli; Luo, Jun; Wu, Peng; Xie, Shaorong; Li, Hengyu
2015-01-01
A symmetric Kullback-Leibler metric based tracking system, capable of tracking moving targets, is presented for a bionic spherical parallel mechanism to minimize a tracking error function to simulate smooth pursuit of human eyes. More specifically, we propose a real-time moving target tracking algorithm which utilizes spatial histograms taking into account symmetric Kullback-Leibler metric. In the proposed algorithm, the key spatial histograms are extracted and taken into particle filtering framework. Once the target is identified, an image-based control scheme is implemented to drive bionic spherical parallel mechanism such that the identified target is to be tracked at the center of the captured images. Meanwhile, the robot motion information is fed forward to develop an adaptive smooth tracking controller inspired by the Vestibuloocular Reflex mechanism. The proposed tracking system is designed to make the robot track dynamic objects when the robot travels through transmittable terrains, especially bumpy environment. To perform bumpy-resist capability under the condition of violent attitude variation when the robot works in the bumpy environment mentioned, experimental results demonstrate the effectiveness and robustness of our bioinspired tracking system using bionic spherical parallel mechanism inspired by head-eye coordination.
El-Nahal, Fady I.
2017-01-01
We investigate a wavelength-division-multiplexing passive optical network (WDM-PON) with centralized lightwave and direct detection. The system is demonstrated for symmetric 10 Gbit/s differential phase-shift keying (DPSK) downstream signals and on-off keying (OOK) upstream signals, respectively. A wavelength reused scheme is employed to carry the upstream data by using a reflective semiconductor optical amplifier (RSOA) as an intensity modulator at the optical network unit (ONU). The constant-intensity property of the DPSK modulation format can keep high extinction ratio ( ER) of downstream signal and reduce the crosstalk to the upstream signal. The bit error rate ( BER) performance of our scheme shows that the proposed 10 Gbit/s symmetric WDM-PON can achieve error free transmission over 25-km-long fiber transmission with low power penalty.
Bracing Zonohedra With Special Faces
Directory of Open Access Journals (Sweden)
Nagy Gyula
2015-12-01
Full Text Available The analysis of simpler preliminary design gives useful input for more complicated three-dimensional building frame structure. A zonohedron, as a preliminary structure of design, is a convex polyhedron for which each face possesses central symmetry. We considered zonohedron as a special framework with the special assumption that the polygonal faces can be deformed in such a way that faces remain planar and centrally symmetric, moreover the length of all edges remains unchanged. Introducing some diagonal braces we got a new mechanism. This paper deals with the flexibility of this kind of mechanisms, and investigates the rigidity of the braced framework. The flexibility of the framework can be characterized by some vectors, which represent equivalence classes of the edges. A necessary and sufficient condition for the rigidity of the braced rhombic face zonohedra is posed. A real mechanical construction, based on two simple elements, provides a CAD prototype of these new mechanisms.
Bates, Alice P; Kennedy, Rodney A
2015-01-01
We propose a sampling scheme on the sphere and develop a corresponding spherical harmonic transform (SHT) for the accurate reconstruction of the diffusion signal in diffusion magnetic resonance imaging (dMRI). By exploiting the antipodal symmetry, we design a sampling scheme that requires the optimal number of samples on the sphere, equal to the degrees of freedom required to represent the antipodally symmetric band-limited diffusion signal in the spectral (spherical harmonic) domain. Compared with existing sampling schemes on the sphere that allow for the accurate reconstruction of the diffusion signal, the proposed sampling scheme reduces the number of samples required by a factor of two or more. We analyse the numerical accuracy of the proposed SHT and show through experiments that the proposed sampling allows for the accurate and rotationally invariant computation of the SHT to near machine precision accuracy.
Shao, X.; Veldhuis, Raymond N.J.
2013-01-01
The helper data scheme utilizes a secret key to protect biometric templates. The current helper data scheme requires binary feature representations that introduce quantization error and thus reduce the capacity of biometric channels. For spectral-minutiae based fingerprint recognition systems,
CANONICAL BACKWARD DIFFERENTIATION SCHEMES FOR ...
African Journals Online (AJOL)
This paper describes a new nonlinear backward differentiation schemes for the numerical solution of nonlinear initial value problems of first order ordinary differential equations. The schemes are based on rational interpolation obtained from canonical polynomials. They are A-stable. The test problems show that they give ...
Willcocks, Ann
2017-01-01
Environmental stewardship schemes are an important driver of biodiversity and habitat improvement throughout England, with the provision of funding to land managers to deliver effective land management that will benefit wildlife, habitats, natural resources and the population. Participation in agri-environment schemes is voluntary and much is done to encourage scheme participation. Dartmoor is a designated landscape, a National Park, and a Special Area of Conservation and encompasses areas...
A New Privacy-preserving Path Authentication Scheme using RFID for Supply Chain Management
Directory of Open Access Journals (Sweden)
LEE, Y.
2013-02-01
Full Text Available This paper presents a privacy-preserving path-authentication method for supply chain management using RFID. Compared with previous works, our scheme employs only symmetric encryption and message authentication codes. This reduces computation and communication overhead. The proposed method also supports high-level privacy without the need for tamper-proof tags as compared with the previous methods. Performance analysis demonstrates that the proposed scheme requires far less computation resource than recent works, proving that less than 1 minute is enough to verify 100000 RFIDs in a conventional reader environment.
Zheng, Yuanlin; Yuan, Wen; Chen, Xianfeng; Cao, Zhuangqi
2012-04-23
A widebandwidth optical delay line is a useful device for various fascinating applications, such as optical buffering and processing of ultrafast signal. Here, we experimentally demonstrated effective slow light of sub-picosecond signal over 10 THz frequency range by employing the wide slow light modes in thick symmetrical metal-cladding optical waveguide (SMCOW). Ultrahigh-order guided modes travelling as slow light in waveguide together with strong confinement provided by metal-cladding makes this scheme nearly material dispersion independent and compatible with wide bandwidth operation. © 2012 Optical Society of America
Radiative Yukawa couplings in the simplest left-right symmetric model
Gabrielli, Emidio; Marzola, Luca; Raidal, Martti
2017-02-01
We revisit a recent solution to the flavor hierarchy problem based on the paradigm that Yukawa couplings are, rather than fundamental constants, effective low energy couplings radiatively generated by interactions in a hidden sector of the theory. In the present paper we show that the setup required by this scenario can be set by gauge invariance alone, provided that the standard model gauge group be extended to the left-right symmetric group of S U (2 )L×S U (2 )R×U (1 )Y. The simplest scheme in which Yukawa couplings are forbidden at the tree-level organises the right-handed fermions into doublets and presents an additional Higgs S U (2 )R doublet, responsible for the spontaneous breaking of the S U (2 )R gauge sector. The flavor and chiral symmetry breaking induced by the S U (2 )R breaking is transferred at the one-loop level to the standard model via the dynamics of the hidden sector, which effectively regulates the spread of the effective Yukawa couplings. The emerging left-right symmetric framework recovers additional appealing features typical of these models, allowing for instance to identify the hypercharges of the involved fermions with their B -L charges and offering a straightforward solution to the strong C P problem. The scheme gives rise to a distinguishing phenomenology that potentially can be tested at the LHC and future colliders through the same interactions that result in the radiative generation of Yukawa couplings, as well as by exploiting the properties of the additional S U (2 )R Higgs doublet.
Multiuser Switched Diversity Scheduling Schemes
Shaqfeh, Mohammad; Alouini, Mohamed-Slim
2012-01-01
Multiuser switched-diversity scheduling schemes were recently proposed in order to overcome the heavy feedback requirements of conventional opportunistic scheduling schemes by applying a threshold-based, distributed, and ordered scheduling mechanism. The main idea behind these schemes is that slight reduction in the prospected multiuser diversity gains is an acceptable trade-off for great savings in terms of required channel-state-information feedback messages. In this work, we characterize the achievable rate region of multiuser switched diversity systems and compare it with the rate region of full feedback multiuser diversity systems. We propose also a novel proportional fair multiuser switched-based scheduling scheme and we demonstrate that it can be optimized using a practical and distributed method to obtain the feedback thresholds. We finally demonstrate by numerical examples that switched-diversity scheduling schemes operate within 0.3 bits/sec/Hz from the ultimate network capacity of full feedback sys...
Tokunaga self-similarity for symmetric homogeneous Markov chains
Kovchegov, Y.; Zaliapin, I.
2010-12-01
Hierarchical branching organization is ubiquitous in nature. It is readily seen in river basins, drainage networks, bronchial passages, botanical trees, and snowflakes, to mention but a few. Empirical evidence suggests that one can describe many natural hierarchies by so-called Tokunaga self-similar trees (SSTs) [Shreve, 1969; Tokunaga, 1978; Ossadnik, 1992; Peckham, 1995; Newman et al., 1997; Pelletier and Turcotte, 2000]; Tokunaga SST have been proven to describe the Galton-Watson critical branching [Burd et al., 2000] and a general particle coagulation process [Gabrielov et al., 1999]. Tokunaga SSTs form a special two-parametric class of SSTs that preserves its statistical properties under the operation of pruning, i.e., cutting the leaves. It has been conjectured (Webb and Zaliapin, 2009; Zaliapin et al. 2009) that Tokunaga self-similarity is a characteristic property of the inverse aggregation (coagulation) process. This study provides further evidence in support of this hypothesis by focusing on trees that describe the topological structure of level sets of a time series, so-called level-set trees (LST). We prove that the LST for a symmetric homogeneous Markov chain (HMC) is a Tokunaga SST with the same parameters as the famous Shreve tree and critical Galton-Watson tree. We show, furthermore, that the Tokunaga property holds for any transformation F[X(G(t))] of a symmetric HMC X(t), where F and G are monotone increasing functions, and as a result - for the regular Brownian motion. At the same time, the Tokunaga property does not hold in general in asymmetric HMCs, a Brownian motion with a drift, ARMA, and some other conventional models. We discuss the relation of our results to the Tokunaga self-similarity of the nearest-neighbor trees for random point sets. References: 1. Gabrielov, A., W.I. Newman, D.L. Turcotte (1999) An exactly soluble hierarchical clustering model: inverse cascades, self-similarity, and scaling. Phys. Rev. E, 1999, 60, 5293-5300. 2
The new social housing scheme in Nigeria: How beneficial for the ...
African Journals Online (AJOL)
The Nigerian government recently inaugurated a Special Committee on National Social Housing Scheme (NSHS) with a presidential mandate to provide housing for its less privileged citizens. In the pilot phase of the scheme, the committee was to build 18,000 units of houses across the country before the end of 2006.
DEFF Research Database (Denmark)
Schultz, Ulrik Pagh; Lawall, Julia Laetitia; Consel, Charles
2000-01-01
Design patterns offer many advantages for software development, but can introduce inefficiency into the final program. Program specialization can eliminate such overheads, but is most effective when targeted by the user to specific bottlenecks. Consequently, we propose that these concepts...
A numerical scheme for modelling reacting flow with detailed chemistry and transport.
Energy Technology Data Exchange (ETDEWEB)
Knio, Omar M. (The Johns Hopkins University, Baltimore, MD); Najm, Habib N.; Paul, Phillip H. (Eksigent Technologies LLC, Livermore, CA)
2003-09-01
An efficient projection scheme is developed for the simulation of reacting flow with detailed kinetics and transport. The scheme is based on a zero-Mach-number formulation of the compressible conservation equations for an ideal gas mixture. It is a modified version of the stiff operator-split scheme developed by Knio, Najm & Wyckoff (1999, J. Comput. Phys. 154, 428). Similar to its predecessor, the new scheme relies on Strang splitting of the discrete evolution equations, where diffusion is integrated in two half steps that are symmetrically distributed around a single stiff step for the reaction source terms. The diffusive half-step is integrated using an explicit single-step, multistage, Runge-Kutta-Chebyshev (RKC) method, which replaces the explicit, multi-step, fractional sub-step approach used in the previous formulation. This modification maintains the overall second-order convergence properties of the scheme and enhances the efficiency of the computations by taking advantage of the extended real-stability region of the RKC scheme. Two additional efficiency-enhancements are also explored, based on an extrapolation procedure for the transport coefficients and on the use of approximate Jacobian data evaluated on a coarse mesh. By including these enhancement schemes, performance tests using 2D computations with a detailed C{sub 1}C{sub 2} methane-air mechanism and a detailed mixture-averaged transport model indicate that speedup factors of about 15 are achieved over the previous split-stiff scheme.
Kumari, Saru; Khan, Muhammad Khurram; Kumar, Rahul
2013-08-01
To ensure reliable telecare services some user authentication schemes for telecare medical information system (TMIS) have been presented in literature. These schemes are proposed with intent to regulate only authorized access to medical services so that medical information can be protected from misuse. Very recently Jiang et al. proposed a user authentication scheme for TMIS which they claimed to provide enhanced privacy. They made use of symmetric encryption/decryption with cipher block chaining mode (CBC) to achieve the claimed user privacy. Their scheme provides features like user anonymity and user un-traceability unlike its preceding schemes on which it is built. Unluckily, authors overlook some important aspects in designing their scheme due to which it falls short to resist user impersonation attack, guessing attacks and denial of service attack. Besides, its password change phase is not secure; air message confidentiality is at risk and also has some other drawbacks. Therefore, we propose an improved scheme free from problems observed in Jiang et al.'s scheme and more suitable for TMIS.
DEFF Research Database (Denmark)
Mousten, Birthe; Laursen, Anne Lise
2016-01-01
Across different fields of research, one feature is often overlooked: the use of language for specialized purposes (LSP) as a cross-discipline. Mastering cross-disciplinarity is the precondition for communicating detailed results within any field. Researchers in specialized languages work cross-d...... of more empirical studies and in terms of a greater application of the results would give language specialists in trade and industry a solid and updated basis for communication and language use....... science fields communicate their findings. With this article, we want to create awareness of the work in this special area of language studies and of the inherent cross-disciplinarity that makes LSP special compared to common-core language. An acknowledgement of the importance of this field both in terms......Across different fields of research, one feature is often overlooked: the use of language for specialized purposes (LSP) as a cross-discipline. Mastering cross-disciplinarity is the precondition for communicating detailed results within any field. Researchers in specialized languages work cross...
Dumbser, Michael; Peshkov, Ilya; Romenski, Evgeniy; Zanotti, Olindo
2017-11-01
In this paper, we propose a new unified first order hyperbolic model of Newtonian continuum mechanics coupled with electro-dynamics. The model is able to describe the behavior of moving elasto-plastic dielectric solids as well as viscous and inviscid fluids in the presence of electro-magnetic fields. It is actually a very peculiar feature of the proposed PDE system that viscous fluids are treated just as a special case of elasto-plastic solids. This is achieved by introducing a strain relaxation mechanism in the evolution equations of the distortion matrix A, which in the case of purely elastic solids maps the current configuration to the reference configuration. The model also contains a hyperbolic formulation of heat conduction as well as a dissipative source term in the evolution equations for the electric field given by Ohm's law. Via formal asymptotic analysis we show that in the stiff limit, the governing first order hyperbolic PDE system with relaxation source terms tends asymptotically to the well-known viscous and resistive magnetohydrodynamics (MHD) equations. Furthermore, a rigorous derivation of the model from variational principles is presented, together with the transformation of the Euler-Lagrange differential equations associated with the underlying variational problem from Lagrangian coordinates to Eulerian coordinates in a fixed laboratory frame. The present paper hence extends the unified first order hyperbolic model of Newtonian continuum mechanics recently proposed in [110,42] to the more general case where the continuum is coupled with electro-magnetic fields. The governing PDE system is symmetric hyperbolic and satisfies the first and second principle of thermodynamics, hence it belongs to the so-called class of symmetric hyperbolic thermodynamically compatible systems (SHTC), which have been studied for the first time by Godunov in 1961 [61] and later in a series of papers by Godunov and Romenski [67,69,119]. An important feature of the
Research on multi-user encrypted search scheme in cloud environment
Yu, Zonghua; Lin, Sui
2017-05-01
Aiming at the existing problems of multi-user encrypted search scheme in cloud computing environment, a basic multi-user encrypted scheme is proposed firstly, and then the basic scheme is extended to an anonymous hierarchical management authority. Compared with most of the existing schemes, the scheme not only to achieve the protection of keyword information, but also to achieve the protection of user identity privacy; the same time, data owners can directly control the user query permissions, rather than the cloud server. In addition, through the use of a special query key generation rules, to achieve the hierarchical management of the user's query permissions. The safety analysis shows that the scheme is safe and that the performance analysis and experimental data show that the scheme is practicable.
Coordinated renewable energy support schemes
DEFF Research Database (Denmark)
Morthorst, P.E.; Jensen, S.G.
2006-01-01
This paper illustrates the effect that can be observed when support schemes for renewable energy are regionalised. Two theoretical examples are used to explain interactive effects on, e.g., the price of power, conditions for conventional power producers, and changes in import and export of power...... RES-E support schemes already has a common liberalised power market. In this case the introduction of a common support scheme for renewable technologies will lead to more efficient sitings of renewable plants, improving economic and environmental performance of the total power system...
Conserving GW scheme for nonequilibrium quantum transport in molecular contacts
DEFF Research Database (Denmark)
Thygesen, Kristian Sommer; Rubio, Angel
2008-01-01
demonstrate that the one-shot G(0)W(0) approximation can produce severe errors, in particular, at high bias. Finally, we consider a benzene molecule between featureless leads. It is found that the molecule's highest occupied molecular orbital-lowest unoccupied molecular orbital gap as calculated in GW......We give a detailed presentation of our recent scheme to include correlation effects in molecular transport calculations using the nonequilibrium Keldysh formalism. The scheme is general and can be used with any quasiparticle self-energy, but for practical reasons, we mainly specialize to the so...
The Grothendieck-Riemann-Roch theorem for group scheme actions
Koeck, B.
1998-01-01
Let G be a group or a group scheme. We establish formulas for the equivariant Euler characteristic of locally free G-modules on a projective G-scheme X: We prove an Adams- Riemann-Roch theorem and, under a certain continuity assumption for the push-forward map, a Grothendieck-Riemann- Roch theorem in (higher) equivariant algebraic K-theory. Furthermore, we present the following applications: The Adams-Riemann-Roch theorem specializes to an interchanging rule between Adams operations and induc...
Symmetrical Parameterization of Rigid Body Transformations for Biomolecular Structures.
Kim, Jin Seob; Chirikjian, Gregory S
2018-01-01
Assessing preferred relative rigid body position and orientation is important in the description of biomolecular structures (such as proteins) and their interactions. In this article, we extend and apply the "symmetrical parameterization," which we recently introduced in the kinematics community, to address problems in structural biology. We also review parameterization methods that are widely used in structural biology to describe relative rigid body motions (in particular, orientations) as a basis for comparison. The new symmetrical parameterization is useful in describing the relative biomolecular rigid body motions, where the parameters are symmetrical in the sense that the subunits of a complex biomolecular structure are described in the same way for the corresponding motion and its inverse. The properties of this new parameterization, singularity analysis, and inverse kinematics are also investigated in more detail. Finally, parameterization is applied to real biomolecular structures and a potential application to structure modeling of symmetric macromolecules to show the efficacy of the symmetrical parameterization in the field of computational structural biology.
Optomechanically induced absorption in parity-time-symmetric optomechanical systems
Zhang, X. Y.; Guo, Y. Q.; Pei, P.; Yi, X. X.
2017-06-01
We explore the optomechanically induced absorption (OMIA) in a parity-time- (PT -) symmetric optomechanical system (OMS). By numerically calculating the Lyapunov exponents, we find out the stability border of the PT -symmetric OMS. The results show that in the PT -symmetric phase the system can be either stable or unstable depending on the coupling constant and the decay rate. In the PT -symmetric broken phase the system can have a stable state only for small gain rates. By calculating the transmission rate of the probe field, we find that there is an inverted optomechanically induced transparency (OMIT) at δ =-ωM and an OMIA at δ =ωM for the PT -symmetric optomechanical system. At each side of δ =-ωM there is an absorption window due to the resonance absorption of the two generated supermodes. Comparing with the case of optomechanics coupled to a passive cavity, we find that the active cavity can enhance the resonance absorption. The absorption rate at δ =ωM increases as the coupling strength between the two cavities increases. Our work provides us with a promising platform for controlling light propagation and light manipulation in terms of PT symmetry, which might have potential applications in quantum information processing and quantum optical devices.
A Novel Iris Segmentation Scheme
Directory of Open Access Journals (Sweden)
Chen-Chung Liu
2014-01-01
Full Text Available One of the key steps in the iris recognition system is the accurate iris segmentation from its surrounding noises including pupil, sclera, eyelashes, and eyebrows of a captured eye-image. This paper presents a novel iris segmentation scheme which utilizes the orientation matching transform to outline the outer and inner iris boundaries initially. It then employs Delogne-Kåsa circle fitting (instead of the traditional Hough transform to further eliminate the outlier points to extract a more precise iris area from an eye-image. In the extracted iris region, the proposed scheme further utilizes the differences in the intensity and positional characteristics of the iris, eyelid, and eyelashes to detect and delete these noises. The scheme is then applied on iris image database, UBIRIS.v1. The experimental results show that the presented scheme provides a more effective and efficient iris segmentation than other conventional methods.
Good governance for pension schemes
Thornton, Paul
2011-01-01
Regulatory and market developments have transformed the way in which UK private sector pension schemes operate. This has increased demands on trustees and advisors and the trusteeship governance model must evolve in order to remain fit for purpose. This volume brings together leading practitioners to provide an overview of what today constitutes good governance for pension schemes, from both a legal and a practical perspective. It provides the reader with an appreciation of the distinctive characteristics of UK occupational pension schemes, how they sit within the capital markets and their social and fiduciary responsibilities. Providing a holistic analysis of pension risk, both from the trustee and the corporate perspective, the essays cover the crucial role of the employer covenant, financing and investment risk, developments in longevity risk hedging and insurance de-risking, and best practice scheme administration.
Breeding schemes in reindeer husbandry
Directory of Open Access Journals (Sweden)
Lars Rönnegård
2003-04-01
Full Text Available The objective of the paper was to investigate annual genetic gain from selection (G, and the influence of selection on the inbreeding effective population size (Ne, for different possible breeding schemes within a reindeer herding district. The breeding schemes were analysed for different proportions of the population within a herding district included in the selection programme. Two different breeding schemes were analysed: an open nucleus scheme where males mix and mate between owner flocks, and a closed nucleus scheme where the males in non-selected owner flocks are culled to maximise G in the whole population. The theory of expected long-term genetic contributions was used and maternal effects were included in the analyses. Realistic parameter values were used for the population, modelled with 5000 reindeer in the population and a sex ratio of 14 adult females per male. The standard deviation of calf weights was 4.1 kg. Four different situations were explored and the results showed: 1. When the population was randomly culled, Ne equalled 2400. 2. When the whole population was selected on calf weights, Ne equalled 1700 and the total annual genetic gain (direct + maternal in calf weight was 0.42 kg. 3. For the open nucleus scheme, G increased monotonically from 0 to 0.42 kg as the proportion of the population included in the selection programme increased from 0 to 1.0, and Ne decreased correspondingly from 2400 to 1700. 4. In the closed nucleus scheme the lowest value of Ne was 1300. For a given proportion of the population included in the selection programme, the difference in G between a closed nucleus scheme and an open one was up to 0.13 kg. We conclude that for mass selection based on calf weights in herding districts with 2000 animals or more, there are no risks of inbreeding effects caused by selection.
Iterative Speedup by Utilizing Symmetric Data in Pricing Options with Two Risky Assets
Directory of Open Access Journals (Sweden)
Dohyun Pak
2017-01-01
Full Text Available The Crank–Nicolson method can be used to solve the Black–Scholes partial differential equation in one-dimension when both accuracy and stability is of concern. In multi-dimensions, however, discretizing the computational grid with a Crank–Nicolson scheme requires significantly large storage compared to the widely adopted Operator Splitting Method (OSM. We found that symmetrizing the system of equations resulting from the Crank–Nicolson discretization help us to use the standard pre-conditioner for the iterative matrix solver and reduces the number of iterations to get an accurate option values. In addition, the number of iterations that is required to solve the preconditioned system, resulting from the proposed iterative Crank–Nicolson scheme, does not grow with the size of the system. Thus, we can effectively reduce the order of complexity in multidimensional option pricing. The numerical results are compared to the one with implicit Operator Splitting Method (OSM to show the effectiveness.
Flux-corrected transport algorithms preserving the eigenvalue range of symmetric tensor quantities
Lohmann, Christoph
2017-12-01
This paper presents a new approach to constraining the eigenvalue range of symmetric tensors in numerical advection schemes based on the flux-corrected transport (FCT) algorithm and a continuous finite element discretization. In the context of element-based FEM-FCT schemes for scalar conservation laws, the numerical solution is evolved using local extremum diminishing (LED) antidiffusive corrections of a low order approximation which is assumed to satisfy the relevant inequality constraints. The application of a limiter to antidiffusive element contributions guarantees that the corrected solution remains bounded by the local maxima and minima of the low order predictor. The FCT algorithm to be presented in this paper guarantees the LED property for the maximal and minimal eigenvalues of the transported tensor at the low order evolution step. At the antidiffusive correction step, this property is preserved by limiting the antidiffusive element contributions to all components of the tensor in a synchronized manner. The definition of the element-based correction factors for FCT is based on perturbation bounds for auxiliary tensors which are constrained to be positive semidefinite to enforce the generalized LED condition. The derivation of sharp bounds involves calculating the roots of polynomials of degree up to 3. As inexpensive and numerically stable alternatives, limiting techniques based on appropriate estimates are considered. The ability of the new limiters to enforce local bounds for the eigenvalue range is confirmed by numerical results for 2D advection problems.
A Novel Symmetrical Split Ring Resonator Based on Microstrip for Microwave Sensors
Directory of Open Access Journals (Sweden)
Alahnomi Rammah A.
2016-02-01
Full Text Available In this paper, novel symmetrical split ring resonator (SSRR is proposed as a suitable component for performance enhancement of microwave sensors. SSRR has been employed for enhancing the insertion loss of the microwave sensors. Using the same device area, we can achieve a high Q-factor of 141.54 from the periphery enhancement using Quasi-linear coupling SSRR, whereas loose coupling SSRR can achieve a Q-factor of 33.98 only. Using Quasi-linear coupling SSRR, the Q-factor is enhanced 4.16 times the loose coupling SSRR using the same device area. After the optimization was made, the SSRR sensor with loose coupling scheme has achieved a very high Qfactor value around 407.34 while quasi-linear scheme has achieved high Q-factor value of 278.78 at the same operating frequency with smaller insertion loss. Spurious passbands at 1st, 2nd, 3rd, and 4th harmonics have been completely suppressed well above -20 dB rejection level without visible changes in the passband filter characteristics. The most significant of using SSRR is to be used for various industrial applications such as food industry, quality control, bio-sensing medicine and pharmacy. The simulation result that Quasi-linear coupling SSRR is a viable candidate for the performance enhancement of microwave sensors has been verified.
Lagrangian formulation of symmetric space sine-Gordon models
Bakas, Ioannis; Shin, H J; Park, Q Han
1996-01-01
The symmetric space sine-Gordon models arise by conformal reduction of ordinary 2-dim \\sigma-models, and they are integrable exhibiting a black-hole type metric in target space. We provide a Lagrangian formulation of these systems by considering a triplet of Lie groups F \\supset G \\supset H. We show that for every symmetric space F/G, the generalized sine-Gordon models can be derived from the G/H WZW action, plus a potential term that is algebraically specified. Thus, the symmetric space sine-Gordon models describe certain integrable perturbations of coset conformal field theories at the classical level. We also briefly discuss their vacuum structure, Backlund transformations, and soliton solutions.
Accessing the exceptional points of parity-time symmetric acoustics
Shi, Chengzhi; Dubois, Marc; Chen, Yun; Cheng, Lei; Ramezani, Hamidreza; Wang, Yuan; Zhang, Xiang
2016-01-01
Parity-time (PT) symmetric systems experience phase transition between PT exact and broken phases at exceptional point. These PT phase transitions contribute significantly to the design of single mode lasers, coherent perfect absorbers, isolators, and diodes. However, such exceptional points are extremely difficult to access in practice because of the dispersive behaviour of most loss and gain materials required in PT symmetric systems. Here we introduce a method to systematically tame these exceptional points and control PT phases. Our experimental demonstration hinges on an active acoustic element that realizes a complex-valued potential and simultaneously controls the multiple interference in the structure. The manipulation of exceptional points offers new routes to broaden applications for PT symmetric physics in acoustics, optics, microwaves and electronics, which are essential for sensing, communication and imaging. PMID:27025443
Radon transformation on reductive symmetric spaces:Support theorems
DEFF Research Database (Denmark)
Kuit, Job Jacob
2013-01-01
We introduce a class of Radon transforms for reductive symmetric spaces, including the horospherical transforms, and derive support theorems for these transforms. A reductive symmetric space is a homogeneous space G/H for a reductive Lie group G of the Harish-Chandra class, where H is an open...... subgroup of the fixed-point subgroup for an involution σ on G. Let P be a parabolic subgroup such that σ(P) is opposite to P and let NP be the unipotent radical of P. For a compactly supported smooth function ϕ on G/H, we define RP(ϕ)(g) to be the integral of NP∋n↦ϕ(gn⋅H) over NP. The Radon transform RP...... is based on the relation between the Radon transform and the Fourier transform on G/H, and a Paley–Wiener-shift type argument. Our results generalize the support theorem of Helgason for the Radon transform on a Riemannian symmetric space....
Energy flows in 𝒫𝒯-symmetric waveguides
Zezyulin, Dmitry A.; Barashenkov, I. V.; Konotop, Vladimir V.
2017-09-01
A parity-time (𝒫𝒯-) symmetric structure can be implemented by coupling an active element to a lossy one. Any stationary process in such a bicentric configuration must be sustained by the energy flux directed from active region to the domain of dissipation. We study these energy currents arising in 𝒫𝒯-symmetric systems and examine the dependence of the flux strength on the gain-and-loss amplitude. First, we address stationary spatially localized modes and demonstrate the existence of the anomalous regime, where the increase of the gain-and-loss rate produces the drop of the flux through the gain-loss interface. Additionally, we consider spatially extended nonlinear patterns in the form of 𝒫𝒯-symmetric through-flows. Some nonlinear solutions are found in exact analytical form.
Free vibration of symmetric and sigmoid functionally graded nanobeams
Hamed, M. A.; Eltaher, M. A.; Sadoun, A. M.; Almitani, K. H.
2016-09-01
The objective of this paper was the investigation of vibration characteristics of both nonlinear symmetric power and sigmoid functionally graded nonlocal nanobeams. The volume fractions of metal and ceramic are assumed to be distributed through a beam thickness by sigmoid law distribution and symmetric power function. Structures with symmetric distribution with mid-plane such as ceramic-metal-ceramic and metal-ceramic-metal are proposed. Nonlocal differential Eringen's elasticity is exploited to incorporate size dependency of nanobeam. The kinematic relations of Euler-Bernoulli beam are proposed, with the assumption of a small strain. A nonlocal equation of motion of nanobeam is derived by using principle of virtual work and then discretized by finite element method to obtain numerical solution. Numerical results show the effects of the function distribution, gradient index and nonlocal parameter on natural frequencies of macro- and nanobeam. This model is helpful in the mechanical design of nanoelectromechanical systems manufactured from FGM.
Small N=2 Extremal Black Holes in Special Geometry
Ceresole, Anna; Marrani, Alessio
2010-01-01
We provide an intrinsic classification of the large and small orbits for N=2, 4D extremal black holes on symmetric spaces which does not depend on the duality frame used for the charges or on the special coordinates. A coordinate independent formula for the fake superpotential W, which (at infinity) represents the black hole ADM mass, is given explicitly in terms of invariants of the N=2 special geometry.
Small N=2 extremal black holes in special geometry
Ceresole, Anna; Ferrara, Sergio; Marrani, Alessio
2010-10-01
We provide an intrinsic classification of the large and small orbits for N=2, 4D extremal black holes on symmetric spaces which does not depend on the duality frame used for the charges or on the special coordinates. A coordinate independent formula for the fake superpotential W, which (at infinity) represents the black hole ADM mass, is given explicitly in terms of invariants of the N=2 special geometry.
African Journals Online (AJOL)
Sarra
Introduction. Nephrology is a relatively recent speciality which was. Introduced in tunisia during the nineteenYsixties by. Professor Hassouna Ben Ayed. He introduced peritoneal dialysis, the artificial Nidney and renal biopsy in the department of medicine of Charles Nicole hospital in tunis. Prof. H. Ben Ayed received his ...
Symmetric bends how to join two lengths of cord
Miles, Roger E
1995-01-01
A bend is a knot securely joining together two lengths of cord (or string or rope), thereby yielding a single longer length. There are many possible different bends, and a natural question that has probably occurred to many is: "Is there a 'best' bend and, if so, what is it?"Most of the well-known bends happen to be symmetric - that is, the two constituent cords within the bend have the same geometric shape and size, and interrelationship with the other. Such 'symmetric bends' have great beauty, especially when the two cords bear different colours. Moreover, they have the practical advantage o
Positive projections of symmetric matrices and Jordan algebras
DEFF Research Database (Denmark)
Fuglede, Bent; Jensen, Søren Tolver
2013-01-01
An elementary proof is given that the projection from the space of all symmetric p×p matrices onto a linear subspace is positive if and only if the subspace is a Jordan algebra. This solves a problem in a statistical model.......An elementary proof is given that the projection from the space of all symmetric p×p matrices onto a linear subspace is positive if and only if the subspace is a Jordan algebra. This solves a problem in a statistical model....
Conformally symmetric traversable wormholes in f( G) gravity
Sharif, M.; Fatima, H. Ismat
2016-11-01
We discuss non-static conformally symmetric traversable wormholes for spherically symmetric spacetime using the model f(G)=α Gn, where n>0 and α is an arbitrary constant. We investigate wormhole solutions by taking two types of shape function and found that physically realistic wormholes exist only for even values of n. We also check the validity of flare-out condition, required for wormhole construction, for the shape functions deduced from two types of equation of state. It is found that this condition is satisfied by these functions in all cases except phantom case with non-static conformal symmetry.
Nonspherically Symmetric Collapse in Asymptotically AdS Spacetimes
Bantilan, Hans; Figueras, Pau; Kunesch, Markus; Romatschke, Paul
2017-11-01
We numerically simulate gravitational collapse in asymptotically anti-de Sitter spacetimes away from spherical symmetry. Starting from initial data sourced by a massless real scalar field, we solve the Einstein equations with a negative cosmological constant in five spacetime dimensions and obtain a family of nonspherically symmetric solutions, including those that form two distinct black holes on the axis. We find that these configurations collapse faster than spherically symmetric ones of the same mass and radial compactness. Similarly, they require less mass to collapse within a fixed time.
IS PT -SYMMETRIC QUANTUM THEORY FALSE AS A FUNDAMENTAL THEORY?
Directory of Open Access Journals (Sweden)
Miloslav Znojil
2016-06-01
Full Text Available Yi-Chan Lee et al. claim (cf. Phys. Rev. Lett. 112, 130404 (2014 that the “recent extension of quantum theory to non-Hermitian Hamiltonians” (which is widely known under the nickname of “PT-symmetric quantum theory” is “likely false as a fundamental theory”. By their opinion their results “essentially kill any hope of PT-symmetric quantum theory as a fundamental theory of nature”. In our present text we explain that their toy-model-based considerations are misleading and that they do not imply any similar conclusions.
Color-symmetric superconductivity in a phenomenological QCD model
DEFF Research Database (Denmark)
Bohr, Henrik; Providencia, C.; Providencia, J. da
2009-01-01
In this paper, we construct a theory of the NJL type where superconductivity is present, and yet the superconducting state remains, in the average, color symmetric. This shows that the present approach to color superconductivity is consistent with color singletness. Indeed, quarks are free...... in the deconfined phase, but the deconfined phase itself is believed to be a color singlet. The usual description of the color superconducting state violates color singletness. On the other hand, the color superconducting state here proposed is color symmetric in the sense that an arbitrary color rotation leads...
CRKSPH - A Conservative Reproducing Kernel Smoothed Particle Hydrodynamics Scheme
Frontiere, Nicholas; Owen, J Michael
2016-01-01
We present a formulation of smoothed particle hydrodynamics (SPH) that employs a first-order consistent reproducing kernel function, exactly interpolating linear fields with particle tracers. Previous formulations using reproducing kernel (RK) interpolation have had difficulties maintaining conservation of momentum due to the fact the RK kernels are not, in general, spatially symmetric. Here, we utilize a reformulation of the fluid equations such that mass, momentum, and energy are all manifestly conserved without any assumption about kernel symmetries. Additionally, by exploiting the increased accuracy of the RK method's gradient, we formulate a simple limiter for the artificial viscosity that reduces the excess diffusion normally incurred by the ordinary SPH artificial viscosity. Collectively, we call our suite of modifications to the traditional SPH scheme Conservative Reproducing Kernel SPH, or CRKSPH. CRKSPH retains the benefits of traditional SPH methods (such as preserving Galilean invariance and manif...
DEFF Research Database (Denmark)
Kleindienst, Ingo; Geisler Asmussen, Christian; Hutzschenreuter, Thomas
2012-01-01
little about performance implications, if we do not know, and do not ask, how the firm has diversified. Therefore, building on the two broad arguments of operating flexibility and location-specific commitment, we develop a theoretical framework that focuses on the extent to which a firm's international...... arbitrage strategy is characterized by specialization versus replication and argue that these different strategies may have differential impact on profitability and risk reduction. Developing a sophisticated measure of international specialization and using a unique panel data set of 92 German MNEs to test......Whether and how international diversification and cross-border arbitrage affects firm performance remains one of the major unresolved research questions in the strategy and international business literatures. We propose that knowing how much a firm has internationally diversified tells us very...
Multiuser switched diversity scheduling schemes
Shaqfeh, Mohammad
2012-09-01
Multiuser switched-diversity scheduling schemes were recently proposed in order to overcome the heavy feedback requirements of conventional opportunistic scheduling schemes by applying a threshold-based, distributed, and ordered scheduling mechanism. The main idea behind these schemes is that slight reduction in the prospected multiuser diversity gains is an acceptable trade-off for great savings in terms of required channel-state-information feedback messages. In this work, we characterize the achievable rate region of multiuser switched diversity systems and compare it with the rate region of full feedback multiuser diversity systems. We propose also a novel proportional fair multiuser switched-based scheduling scheme and we demonstrate that it can be optimized using a practical and distributed method to obtain the feedback thresholds. We finally demonstrate by numerical examples that switched-diversity scheduling schemes operate within 0.3 bits/sec/Hz from the ultimate network capacity of full feedback systems in Rayleigh fading conditions. © 2012 IEEE.
Staff Association
2011-01-01
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Staff Association
2010-01-01
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On split Lie algebras with symmetric root systems
Indian Academy of Sciences (India)
... family of its minimal ideals, each one being a simple split Lie algebra with a symmetric root system and having all its nonzero roots connected. Author Affiliations. Antonio J Calderón Martín1. Departamento de Matemáticas, Universidad de Cádiz, 11510 Puerto Real, Cádiz, Spain. Dates. Manuscript received: 24 May 2007 ...
A nine-level hybrid symmetric cascaded multilevel converter for ...
Indian Academy of Sciences (India)
Indrajit Sarkar
Therefore, due to this limitation of asymmetric or hybrid cascaded converters on input power quality, the use of these converters is popular for electric vehicle applications, and have limited industrial use [20]. Several attempts have been made to increase the number of output voltage levels of symmetric CHB–MLCs as well.
Heat kernel analysis for Bessel operators on symmetric cones
DEFF Research Database (Denmark)
Möllers, Jan
2014-01-01
We investigate the heat equation corresponding to the Bessel operators on a symmetric cone $Ω=G/K$. These operators form a one-parameter family of elliptic self-adjoint second order differential operators and occur in the Lie algebra action of certain unitary highest weight representations...
Constructing I[subscript h] Symmetrical Fullerenes from Pentagons
Gan, Li-Hua
2008-01-01
Twelve pentagons are sufficient and necessary to form a fullerene cage. According to this structural feature of fullerenes, we propose a simple and efficient method for the construction of I[subscript h] symmetrical fullerenes from pentagons. This method does not require complicated mathematical knowledge; yet it provides an excellent paradigm for…
Truncated VSV solutions to symmetric rank-deficient problems
Fierro, Richardo D.; Hansen, Per Christian
2001-01-01
Symmetric VSV decompositions are new rank-revealing decompositions that exploit and preserve symmetry. Truncated VSV solutions are stabilized solutions computed by neglecting blocks in the VSV decomposition with small norm. We compare the truncated VSV solutions with truncated SVD solutions and give perturbation bounds for the VSV solutions. Numerical examples illustrate our results.
Truncated VSV solutions to symmetric rank-deficient problems
DEFF Research Database (Denmark)
Fierro, Richardo D.; Hansen, Per Christian
2001-01-01
Symmetric VSV decompositions are new rank-revealing decompositions that exploit and preserve symmetry. Truncated VSV solutions are stabilized solutions computed by neglecting blocks in the VSV decomposition with small norm. We compare the truncated VSV solutions with truncated SVD solutions...... and give perturbation bounds for the VSV solutions. Numerical examples illustrate our results....
Truncated VSV Solutions to Symmetric Rank-Deficient Problems
DEFF Research Database (Denmark)
Fierro, Ricardo D.; Hansen, Per Christian
2002-01-01
Symmetric VSV decompositions are new rank-revealing decompositions that exploit and preserve symmetry. Truncated VSV solutions are stabilized solutions computed by neglecting blocks in the VSV decomposition with small norm. We compare the truncated VSV solutions with truncated SVD solutions...... and give perturbation bounds for the VSV solutions. Numerical examples illustrate our results....
Axially Symmetric Bianchi Type-I Bulk-Viscous Cosmological ...
Indian Academy of Sciences (India)
Abstract. The present study deals with spatially homogeneous and anisotropic axially symmetric Bianchi type-I cosmological model with time variable cosmological term in the presence of bulk viscous fluid. The Einstein's field equations are solved explicitly by time varying decel- eration parameter q. Consequences of the ...
Optical fluxes in coupled PT -symmetric photonic structures
Ge, Li; Makris, Konstantinos G.; Zhang, Lingxuan
2017-08-01
In this work we first examine transverse and longitudinal fluxes in a PT -symmetric photonic dimer using a coupled-mode theory. Several surprising understandings are obtained from this perspective: The longitudinal flux shows that the PT transition in a dimer can be regarded as a classical effect, despite its analogy to PT -symmetric quantum mechanics. The longitudinal flux also indicates that the so-called giant amplification in the PT -symmetric phase is a subexponential behavior and does not outperform a single gain waveguide. The transverse flux, on the other hand, reveals that the apparent power oscillations between the gain and loss waveguides in the PT -symmetric phase can be deceiving in certain cases, where the transverse power transfer is in fact unidirectional. We also show that this power transfer cannot be arbitrarily fast even when the exceptional point is approached. Finally, we go beyond the coupled-mode theory by using the paraxial wave equation and also extend our discussions to a PT diamond and a one-dimensional periodic lattice.
Characterisation of a highly symmetrical miniature capacitive triaxial accelerometer
Lotters, Joost Conrad; Lötters, Joost Conrad; Olthuis, Wouter; Veltink, Petrus H.; Bergveld, Piet
1997-01-01
A highly symmetrical cubic capacitive triaxial accelerometer for biomedical applications has been designed, realised and tested. The sensors are available in two outer dimensions, namely 2×2×2 and 5×5×5 mm3. The devices are mounted on a standard IC package for easy testing. Features of the sensor
From PT-symmetric quantum mechanics to conformal field theory
Indian Academy of Sciences (India)
One of the simplest examples of a P T -symmetric quantum system is the scaling Yang–Lee model, a quantum field theory with cubic interaction and purely imaginary coupling. We give a historical review of some facts about this model in ≤ 2 dimensions, from its original definition in connection with phase transitions in the ...
An invariant symmetric non-selfadjoint differential operator
Thomas, Erik G.F.
2002-01-01
Let D be a symmetric left invariant differential operator on a unimodular Lie group G of type I. Then we show that D is essentially self-adjoint if and only if for almost all pi is an element of (G) over cap, with respect to the Plancherel measure, the operator pi(D) is essentially self-adjoint.
On the stability of convex symmetric polytopes of matrices
Directory of Open Access Journals (Sweden)
Gilner de la Hera Martinez
2000-01-01
Full Text Available In this warticle we investigate the stability properties of a convex symmetric time-varying second-order matrix's polytope depending on a real positive parameter $r$. We apply the results obtained to the calculation of the stability radius of a second order matrix under affine general perturbations, and under linear structured multiple perturbations.
PEO nanocomposite polymer electrolyte for solid state symmetric ...
Indian Academy of Sciences (India)
Physical and electrochemical properties of polyethylene oxide (PEO)-based nanocomposite solid polymer electrolytes (NPEs) were investigated for symmetric capacitor applications. Nanosize fillers, i.e., Al2O3 and SiO2 incorporated polymer electrolyte exhibited higher ionic conductivity than those with filler-free composites ...
SUSY formalism for the symmetric double well potential
Indian Academy of Sciences (India)
SUSY; moving boundary condition; exactly solvable; symmetric double well; NH3 molecule. PACS Nos 02.30.Ik; 03.50. ... Various work has been done to construct the integrable potentials by SUSY Darboüx for- malism. If the boundary .... ϵj being the energy eigenvalue for the jth level. So the obtained potential [1,4,5] is.
Symmetric/asymmetric bifurcation behaviours of a bogie system
DEFF Research Database (Denmark)
Xue-jun, Gao; Ying-hui, Li; Yuan, Yue
2013-01-01
Based on the bifurcation and stability theory of dynamical systems, the symmetric/asymmetric bifurcation behaviours and chaotic motions of a railway bogie system under a complex nonlinear wheel–rail contact relation are investigated in detail by the ‘resultant bifurcation diagram’ method with slo...
Entangling capabilities of symmetric two-qubit gates
Indian Academy of Sciences (India)
2014-07-25
Jul 25, 2014 ... Our work addresses the problem of generating maximally entangled two spin-1/2 (qubit) symmetric states using NMR, NQR, Lipkin–Meshkov–Glick Hamiltonians. Time evolution of such Hamiltonians provides various logic gates which can be used for quantum processing tasks. Pairs of spin-1/2s have ...
first principles derivation of a stress function for axially symmetric
African Journals Online (AJOL)
HOD
In this work, a stress function is derived from first principles to describe the behaviour of three dimensional axially symmetric elasticity problems involving linear elastic, isotropic homogeneous materials. In the process, the fifteen governing partial differential equations of linear isotropic elasticity were reduced to the solution ...
A New Formulation for Symmetric Implicit Runge-Kutta-Nystrom ...
African Journals Online (AJOL)
We further coverted the uniformly accurate order six block hybrid method to symmetric Implicit Runge-Kutta –Nystrom Method by using the direct method as those invented by Nystrom.The convergence of the method is achieved as shown in the table of results. Journal of the Nigerian Association of Mathematical Physics, ...
Separator-Integrated, Reversely Connectable Symmetric Lithium-Ion Battery.
Wang, Yuhang; Zeng, Jiren; Cui, Xiaoqi; Zhang, Lijuan; Zheng, Gengfeng
2016-02-24
A separator-integrated, reversely connectable, symmetric lithium-ion battery is developed based on carbon-coated Li3V2(PO4)3 nanoparticles and polyvinylidene fluoride-treated separators. The Li3V2(PO4)3 nanoparticles are synthesized via a facile solution route followed by calcination in Ar/H2 atmosphere. Sucrose solution is used as the carbon source for uniform carbon coating on the Li3V2(PO4)3 nanoparticles. Both the carbon and the polyvinylidene fluoride treatments substantially improve the cycling life of the symmetric battery by preventing the dissolution and shuttle of the electroactive Li3V2(PO4)3. The obtained symmetric full cell exhibits a reversible capacity of ≈ 87 mA h g(-1), good cycling stability, and capacity retention of ≈ 70% after 70 cycles. In addition, this type of symmetric full cell can be operated in both forward and reverse connection modes, without any influence on the cycling of the battery. Furthermore, a new separator integration approach is demonstrated, which enables the direct deposition of electroactive materials for the battery assembly and does not affect the electrochemical performance. A 10-tandem-cell battery assembled without differentiating the electrode polarity exhibits a low thickness of ≈ 4.8 mm and a high output voltage of 20.8 V. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
On the generation techniques of axially symmetric stationary metrics
Indian Academy of Sciences (India)
General relativity; Einstein's equations; relation between solution generating techniques; soliton technique; method of Gutsunaev–Manko. ... and the soliton technique (for two-soliton solutions) of Belinskii–Zakharov, for generating solutions of axially symmetric stationary space-times in general relativity is discussed.
Symmetric equilibrium strategies in game theoretic real option models
Thijssen, J.J.J.; Huisman, K.J.M.; Kort, P.M.
2012-01-01
This paper considers the problem of investment timing under uncertainty in a duopoly framework. When both firms want to be the first investor a coordination problem arises. Here, a method is proposed to deal with this coordination problem, involving the use of symmetric mixed strategies. The method
Symmetric Equilibrium Strategies in Game Theoretical Real Option Models
Thijssen, J.J.J.; Huisman, K.J.M.; Kort, P.M.
2002-01-01
This paper considers the problem of investment timing under uncertainty in a duopoly framework.When both firms want to be the first investor a coordination problem arises.Here, a method is proposed to deal with this coordination problem, involving the use of symmetric mixed strategies.The method is
Perturbation approximation for orbits in axially symmetric funnels
Nauenberg, Michael
2014-11-01
A perturbation method that can be traced back to Isaac Newton is applied to obtain approximate analytic solutions for objects sliding in axially symmetric funnels in near circular orbits. Some experimental observations are presented for balls rolling in inverted cones with different opening angles, and in a funnel with a hyperbolic surface that approximately simulates the gravitational force.
Experimental technique of calibration of symmetrical air pollution ...
Indian Academy of Sciences (India)
not be correct. This would result in incorrect pre- dictions by the model. In this paper an attempt has been made to develop experimental technique to produce Symmetric Air Pollution Model Index. (SAPMI) that could be used to test the accuracy of the predictions made through such models, before they are actually applied ...
On the generation techniques of axially symmetric stationary metrics
Indian Academy of Sciences (India)
On the generation techniques of axially symmetric stationary metrics. S CHAUDHURI. Department of Physics, Gushkara Mahavidyalaya, Gushkara, Burdwan 713 128, India. Address for correspondence: Chaudhuri Lane, R.K. Palli, Badamtala, Burdwan 713 101, India. MS received 18 October 2000; revised 1 June 2001.
Finite symmetric trilinear integral transform of distributions. Part II
Directory of Open Access Journals (Sweden)
G. L. Waghmare
2006-01-01
Full Text Available The finite symmetric trilinear integral transform is extended to distributions by using quite different technique than Zemanian (1968 and Dube (1976 and an inversion formula is established using Parseval's identity. The operational calculus generated is applied to find the temperature inside an equilateral prism of semi-infinite length.
Symmetrical waveguide devices fabricated by direct UV writing
DEFF Research Database (Denmark)
Færch, Kjartan Ullitz; Svalgaard, Mikael
2002-01-01
Power splitters and directional couplers fabricated by direct UV writing in index matched silica-on-silicon samples can suffer from an asymmetrical device performance, even though the UV writing is carried out in a symmetrical fashion. This effect originates from a reduced photosensitivity...
Symmetric Electrodes for Electrochemical Energy-Storage Devices.
Zhang, Lei; Dou, Shi Xue; Liu, Hua Kun; Huang, Yunhui; Hu, Xianluo
2016-12-01
Increasing environmental problems and energy challenges have so far attracted urgent demand for developing green and efficient energy-storage systems. Among various energy-storage technologies, sodium-ion batteries (SIBs), electrochemical capacitors (ECs) and especially the already commercialized lithium-ion batteries (LIBs) are playing very important roles in the portable electronic devices or the next-generation electric vehicles. Therefore, the research for finding new electrode materials with reduced cost, improved safety, and high-energy density in these energy storage systems has been an important way to satisfy the ever-growing demands. Symmetric electrodes have recently become a research focus because they employ the same active materials as both the cathode and anode in the same energy-storage system, leading to the reduced manufacturing cost and simplified fabrication process. Most importantly, this feature also endows the symmetric energy-storage system with improved safety, longer lifetime, and ability of charging in both directions. In this Progress Report, we provide the comprehensive summary and comment on different symmetric electrodes and focus on the research about the applications of symmetric electrodes in different energy-storage systems, such as the above mentioned SIBs, ECs and LIBs. Further considerations on the possibility of mass production have also been presented.
Symmetrical and asymmetrical growth restriction in preterm-born children
Bocca-Tjeertes, Inger; Bos, Arend; Kerstjens, Jorien; de Winter, Andrea; Reijneveld, Sijmen
OBJECTIVE: To determine how symmetric (proportionate; SGR) and asymmetric (disproportionate; AGR) growth restriction influence growth and development in preterms from birth to 4 years. METHODS: This community-based cohort study of 810 children comprised 86 SGR, 61 AGR, and 663 non-growth restricted
Report on the Dynamical Evolution of an Axially Symmetric Quasar ...
Indian Academy of Sciences (India)
The role of the angular momentum in the regular or chaotic character of motion in an axially symmetric quasar model is examined. It is found that, for a given value of the critical angular momentum , there are two values of the mass of the nucleus for which transition from regular to chaotic motion occurs.
Enhanced Antenna Performances Using Planar Circularly Symmetric EBG's
Maagt, P. de; Llombart, N.; Neto, A.; Gerini, G.
2005-01-01
Planar circularly symmetric (PCS) electromagnetic band-gap (EBG) substrates have recently been proposed to suppress surface waves (Llombart, N. et al., 2004). The application of PCS-EBG to reduce the surface waves excited by an antenna printed on a dielectric slab is discussed. The study starts from
Symmetric Dimethylarginine in Cats with Hypertrophic Cardiomyopathy and Diabetes Mellitus
DEFF Research Database (Denmark)
Langhorn, R.; Kieler, I. N.; Koch, J.
2018-01-01
Background: Symmetric dimethylarginine (SDMA) has been increasingly used as a marker of early chronic kidney disease (CKD) in cats, but little is known about the influence of comorbidities on SDMA in this species. Hypothesis: Hypertrophic cardiomyopathy (HCM) and diabetes mellitus (DM), independe...
Bilaterally symmetrical foramina on the parietal bone of the bovine ...
African Journals Online (AJOL)
Different bovine skull developmental defects have been reported with variable frequency of occurrence. We hereby report a bilaterally symmetrical parietal foramina in a processed skull meant for osteological practical at the Department of Veterinary Anatomy, University of Jos, Nigeria. The depths of each of the foramina ...
An optimal version of an inequality involving the third symmetric ...
Indian Academy of Sciences (India)
yuanshufeng2003@163.com. MS received 28 April 2006; revised 12 August 2008. Abstract. Let (GA)[k] n (a), An(a), Gn(a) be the third symmetric mean of k degree, the arithmetic and geometric means of a1,...,an (ai > 0,i = 1,...,n), respectively. By means of descending dimension method, we prove that the maximum of p is.
Plane Symmetric Cosmological Model with Quark and Strange ...
Indian Academy of Sciences (India)
Home; Journals; Journal of Astrophysics and Astronomy; Volume 38; Issue 1. Plane Symmetric Cosmological Model with Quark and Strange Quark Matter in f ( R , T ) Theory of Gravity. P. K. AGRAWAL D. D. PAWAR. Research Article Volume 38 Issue 1 March 2017 Article ID 2 ...
Coupled dilaton and electromagnetic field in cylindrically symmetric ...
Indian Academy of Sciences (India)
An exact solution is obtained for coupled dilaton and electromagnetic ﬁeld in a cylindrically symmetric spacetime where an axial magnetic ﬁeld as well as a radial electric ﬁeld both are present. Depending on the choice of the arbitrary constants our solution reduces either to dilatonic gravity with pure electric ﬁeld or to that ...
Directory of Open Access Journals (Sweden)
Bin Gao
2016-08-01
Full Text Available Abstract The single image super-resolution (SISR problem represents a class of efficient models appealing in many computer vision applications. In this paper, we focus on designing a proximal symmetric alternating direction method of multipliers (SADMM for the SISR problem. By taking full exploitation of the special structure, the method enjoys the advantage of being easily implementable by linearizing the quadratic term of subproblems in the SISR problem. With this linearization, the resulting subproblems easily achieve closed-form solutions. A global convergence result is established for the proposed method. Preliminary numerical results demonstrate that the proposed method is efficient and the computing time is saved by nearly 40% compared with several state-of-the-art methods.
Spectral and thermodynamical properties of symmetric nuclear matter with Gogny interaction
Energy Technology Data Exchange (ETDEWEB)
Ventura, J. (Departament d' Estructura i Constituents de la Materia, Facultat de Fisica, Universitat de Barcelona, E-08028 Barcelona (Spain)); Polls, A. (Departament d' Estructura i Constituents de la Materia, Facultat de Fisica, Universitat de Barcelona, E-08028 Barcelona (Spain)); Vinas, X. (Departament d' Estructura i Constituents de la Materia, Facultat de Fisica, Universitat de Barcelona, E-08028 Barcelona (Spain)); Hernandez, E.S. (Departamento de Fisica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, RA-1428 Buenos Aires (Argentina))
1994-10-03
The finite range effects of an effective force on the single particle properties and the particle-hole effective interaction are investigated in a wide interval of temperatures. The calculations are performed in a framework of a thermal Hartree-Fock method using the D1-Gogny density dependent interaction. First, the behaviour of the single particle potential, effective mass and the momentum distribution is discussed. The competition between statistical correlations and mean field effects is studied by analyzing the relative momentum distribution and the two-body distribution function. Secondly, a possible extension of the Landau Fermi liquid theory to finite temperatures is discussed in the context of symmetric nuclear matter. Special attention is devoted to the meaning of the Landau parameters and to the requirements for thermodynamic stability. In particular, the relation between the nuclear incompressibility and the F[sub 0][sup ss]-Landau amplitude at finite temperatures is carefully analyzed. ((orig.))
Propagation of symmetric tunable dual airy beam through ABCD optical system
Wen, Wei; Chu, Xiuxiang
2014-12-01
A simple mathematical model is proposed to describe symmetric tunable dual Airy beam (STDAB) [Opt. Lett. 39 (2014) 2370; Opt. Lett. 38 (2013) 1286; Opt. Lett. 37 (2012) 3402]. This beam is composed of two conventional Airy beams with a tunable parameter which have several distinguishing features. For example, the intensity distribution of the beam can be Gaussian, elliptical Gaussian, rectangular Gaussian or dumbbell shaped with difference tunable parameters. Based on the Collins integral formula, an analytical expression of the STDAB passing through a paraxial ABCD optical system is derived. For special cases, the propagation properties of the beams in free space and in chiral medium, passing a thin lens and passing a fractional Fourier transformation system are studied.
Positive radially symmetric solution for a system of quasilinear biharmonic equations in the plane
Directory of Open Access Journals (Sweden)
Joshua Barrow
2015-01-01
Full Text Available We study the boundary value system for the two-dimensional quasilinear biharmonic equations $$\\displaylines{ \\Delta (|\\Delta u_i|^{p-2}\\Delta u_i=\\lambda_iw_i(xf_i(u_1,\\ldots,u_m,\\quad x\\in B_1,\\cr u_i=\\Delta u_i=0,\\quad x\\in\\partial B_1,\\quad i=1,\\ldots,m, }$$ where $B_1=\\{x\\in\\mathbb{R}^2:|x|<1\\}$. Under some suitable conditions on $w_i$ and $f_i$, we discuss the existence, uniqueness, and dependence of positive radially symmetric solutions on the parameters $\\lambda_1,\\ldots,\\lambda_m$. Moreover, two sequences are constructed so that they converge uniformly to the unique solution of the problem. An application to a special problem is also presented.
Modulation Schemes for Wireless Access
Directory of Open Access Journals (Sweden)
F. Vejrazka
2000-12-01
Full Text Available Four modulation schemes, namely minimum shift keying (MSK, Gaussianminimum shift keying (GMSK, multiamplitude minimum shift keying(MAMSK and ÃÂ€/4 differential quadrature phase shift keying (ÃÂ€/4-QPSKare described and their applicability to wireless access is discussedin the paper. Low complexity receiver structures based on differentialdetection are analysed to estimate the performance of the modulationschemes in the additive Gaussian noise and the Rayleigh and Riceenvelope fast fading channel. The bandwidth efficiency is calculated toevaluate the modulation schemes. The results show that the MAMSK schemegives the greatest bandwidth efficiency, but its performance in theRayleigh channel is rather poor. In contrast, the MSK scheme is lessbandwidth efficient, but it is more resistant to Rayleigh fading. Theperformance of ÃÂ€/4-QPSK signal is considerably improved by appropriateprefiltering.
Electrical Injection Schemes for Nanolasers
DEFF Research Database (Denmark)
Lupi, Alexandra; Chung, Il-Sug; Yvind, Kresten
2014-01-01
Three electrical injection schemes based on recently demonstrated electrically pumped photonic crystal nanolasers have been numerically investigated: 1) a vertical p-i-n junction through a post structure; 2) a lateral p-i-n junction with a homostructure; and 3) a lateral p-i-n junction....... For this analysis, the properties of different schemes, i.e., electrical resistance, threshold voltage, threshold current, and internal efficiency as energy requirements for optical interconnects are compared and the physics behind the differences is discussed....
Side-coupled slab-symmetric structure for high-gradient acceleration using terahertz power
Directory of Open Access Journals (Sweden)
R. B. Yoder
2005-11-01
Full Text Available A slab-symmetric dielectric-loaded accelerator structure, consisting of a vacuum gap between dielectric-lined conducting walls, is described. The device is resonantly excited by an external drive laser which is side coupled into the acceleration region; a novel coupling scheme, which consists of an array of narrow, equally spaced slots in the upper structure boundary, is presented and analyzed in detail. This structure partakes of the advantages of earlier slab-symmetric optical acceleration proposals, but will use a terahertz-frequency external radiation source (λ=340 μm, allowing realistic electron beams to be used in a proof-of-principle experiment. Two- and three-dimensional electromagnetic simulations are used to verify the mode patterns and study the effects of the couplers, including time-dependent calculations of the filling of the structure and particle-in-cell computations of the beam wakefields. Details of the resonance are found to be highly sensitive to the coupling slot geometry: the presence of the couplers can lead to frequency detuning, changes in the field breakdown limits and overall Q factor, and distortions of the field pattern. Beam wakefields are enhanced by the presence of the slots, but found to have no significant effect on the beam transport. The resonant accelerating fields, which are nearly constant along the short transverse direction, are found to have between 10 and 15 times the amplitude of the driving radiation, with only a small (<10% admixture of other nonaccelerating modes. Field gradients are computed to be near 100 MV/m when the structure is driven with 100 MW of terahertz laser power. Possible manufacturing methods for a prototype device are discussed.
Staff Association
2011-01-01
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Staff Association
2011-01-01
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Association du personnel
2011-01-01
Are you a member of the Staff Association? Did you know that as a member you can benefit from the following special offers: BCGE (Banque Cantonale de Genève): personalized banking solutions with preferential conditions. TPG: reduced rates on annual transport passes for active and retired staff. Aquaparc: reduced ticket prices for children and adults at this Swiss waterpark in Le Bouveret. Walibi: reduced prices for children and adults at this French attraction park in Les Avenières. FNAC: 5% reduction on FNAC vouchers. For more information about all these offers, please consult our web site: http://association.web.cern.ch/association/en/OtherActivities/Offers.html
Papp, E
2003-01-01
The DELTA not = 1 generalization of the q-symmetrized Harper equation is discussed in terms of wavefunctions expressed by Laurent series. Proceeding by recursion leads to a nontrivial DELTA-dependent generalization of the characteristic energy polynomial, with a special emphasis on a continuous dependence on the commensurability parameter. The multiplicity parameter which is responsible for the amount of coprime realizations of the commensurability parameter is also accounted for. The present energies have been derived so as to reproduce particular ones obtained before as limiting cases.
Directory of Open Access Journals (Sweden)
Yanrong Lu
2016-06-01
Full Text Available WSNs (Wireless sensor networks are nowadays viewed as a vital portion of the IoTs (Internet of Things. Security is a significant issue in WSNs, especially in resource-constrained environments. AKA (Authentication and key agreement enhances the security of WSNs against adversaries attempting to get sensitive sensor data. Various AKA schemes have been developed for verifying the legitimate users of a WSN. Firstly, we scrutinize Amin-Biswas’s currently scheme and demonstrate the major security loopholes in their works. Next, we propose a lightweight AKA scheme, using symmetric key cryptography based on smart card, which is resilient against all well known security attacks. Furthermore, we prove the scheme accomplishes mutual handshake and session key agreement property securely between the participates involved under BAN (Burrows, Abadi and Needham logic. Moreover, formal security analysis and simulations are also conducted using AVISPA(Automated Validation of Internet Security Protocols and Applications to show that our scheme is secure against active and passive attacks. Additionally, performance analysis shows that our proposed scheme is secure and efficient to apply for resource-constrained WSNs.
Lu, Yanrong; Li, Lixiang; Peng, Haipeng; Yang, Yixian
2016-06-08
WSNs (Wireless sensor networks) are nowadays viewed as a vital portion of the IoTs (Internet of Things). Security is a significant issue in WSNs, especially in resource-constrained environments. AKA (Authentication and key agreement) enhances the security of WSNs against adversaries attempting to get sensitive sensor data. Various AKA schemes have been developed for verifying the legitimate users of a WSN. Firstly, we scrutinize Amin-Biswas's currently scheme and demonstrate the major security loopholes in their works. Next, we propose a lightweight AKA scheme, using symmetric key cryptography based on smart card, which is resilient against all well known security attacks. Furthermore, we prove the scheme accomplishes mutual handshake and session key agreement property securely between the participates involved under BAN (Burrows, Abadi and Needham) logic. Moreover, formal security analysis and simulations are also conducted using AVISPA(Automated Validation of Internet Security Protocols and Applications) to show that our scheme is secure against active and passive attacks. Additionally, performance analysis shows that our proposed scheme is secure and efficient to apply for resource-constrained WSNs.
White, Jeffrey A.; Baurle, Robert A.; Fisher, Travis C.; Quinlan, Jesse R.; Black, William S.
2012-01-01
The 2nd-order upwind inviscid flux scheme implemented in the multi-block, structured grid, cell centered, finite volume, high-speed reacting flow code VULCAN has been modified to reduce numerical dissipation. This modification was motivated by the desire to improve the codes ability to perform large eddy simulations. The reduction in dissipation was accomplished through a hybridization of non-dissipative and dissipative discontinuity-capturing advection schemes that reduces numerical dissipation while maintaining the ability to capture shocks. A methodology for constructing hybrid-advection schemes that blends nondissipative fluxes consisting of linear combinations of divergence and product rule forms discretized using 4th-order symmetric operators, with dissipative, 3rd or 4th-order reconstruction based upwind flux schemes was developed and implemented. A series of benchmark problems with increasing spatial and fluid dynamical complexity were utilized to examine the ability of the candidate schemes to resolve and propagate structures typical of turbulent flow, their discontinuity capturing capability and their robustness. A realistic geometry typical of a high-speed propulsion system flowpath was computed using the most promising of the examined schemes and was compared with available experimental data to demonstrate simulation fidelity.
Distance labeling schemes for trees
DEFF Research Database (Denmark)
Alstrup, Stephen; Gørtz, Inge Li; Bistrup Halvorsen, Esben
2016-01-01
We consider distance labeling schemes for trees: given a tree with n nodes, label the nodes with binary strings such that, given the labels of any two nodes, one can determine, by looking only at the labels, the distance in the tree between the two nodes. A lower bound by Gavoille et al. [Gavoill...
Distance labeling schemes for trees
DEFF Research Database (Denmark)
Alstrup, Stephen; Gørtz, Inge Li; Bistrup Halvorsen, Esben
2016-01-01
(log(n)) bits for constant ε> 0. (1 + ε)-stretch labeling schemes with polylogarithmic label size have previously been established for doubling dimension graphs by Talwar [Talwar, STOC, 2004]. In addition, we present matching upper and lower bounds for distance labeling for caterpillars, showing that labels...
Homogenization scheme for acoustic metamaterials
Yang, Min
2014-02-26
We present a homogenization scheme for acoustic metamaterials that is based on reproducing the lowest orders of scattering amplitudes from a finite volume of metamaterials. This approach is noted to differ significantly from that of coherent potential approximation, which is based on adjusting the effective-medium parameters to minimize scatterings in the long-wavelength limit. With the aid of metamaterials’ eigenstates, the effective parameters, such as mass density and elastic modulus can be obtained by matching the surface responses of a metamaterial\\'s structural unit cell with a piece of homogenized material. From the Green\\'s theorem applied to the exterior domain problem, matching the surface responses is noted to be the same as reproducing the scattering amplitudes. We verify our scheme by applying it to three different examples: a layered lattice, a two-dimensional hexagonal lattice, and a decorated-membrane system. It is shown that the predicted characteristics and wave fields agree almost exactly with numerical simulations and experiments and the scheme\\'s validity is constrained by the number of dominant surface multipoles instead of the usual long-wavelength assumption. In particular, the validity extends to the full band in one dimension and to regimes near the boundaries of the Brillouin zone in two dimensions.
Symmetrical peripheral gangrene: Unusual complication of dengue fever.
Patel, M L; Sachan, Rekha; Verma, Amita; Shyam, Radhey
2016-01-01
Symmetrical peripheral gangrene (SPG) is a rare clinical entity, infective, and noninfective both types of etiologies are responsible. The basic underlying pathology in SPG is being disseminated intravascular coagulation and carries a high mortality. Here, we describe a 52-year-old male with dengue fever, who developed bilateral symmetrical dry gangrene of both hand and feet. His dengue IgM antibody was positive. All the peripheral pulses of the affected limbs were palpable. Color Doppler study of upper and lower limb vessels showed normal flow. The patient was managed with intravenous fluids, low molecular weight heparin, and fresh frozen plasma. His general condition was improved within 72 h with no further progression of gangrene. Clinician should suspect the possibility of SPG while dealing a case of dengue fever presenting as peripheral gangrene.
Modified reactive tabu search for the symmetric traveling salesman problems
Lim, Yai-Fung; Hong, Pei-Yee; Ramli, Razamin; Khalid, Ruzelan
2013-09-01
Reactive tabu search (RTS) is an improved method of tabu search (TS) and it dynamically adjusts tabu list size based on how the search is performed. RTS can avoid disadvantage of TS which is in the parameter tuning in tabu list size. In this paper, we proposed a modified RTS approach for solving symmetric traveling salesman problems (TSP). The tabu list size of the proposed algorithm depends on the number of iterations when the solutions do not override the aspiration level to achieve a good balance between diversification and intensification. The proposed algorithm was tested on seven chosen benchmarked problems of symmetric TSP. The performance of the proposed algorithm is compared with that of the TS by using empirical testing, benchmark solution and simple probabilistic analysis in order to validate the quality of solution. The computational results and comparisons show that the proposed algorithm provides a better quality solution than that of the TS.
Affine equivalence of cubic homogeneous rotation symmetric Boolean functions
Cusick, Thomas W
2010-01-01
Homogeneous rotation symmetric Boolean functions have been extensively studied in recent years because of their applications in cryptography. Little is known about the basic question of when two such functions are affine equivalent. The simplest case of quadratic rotation symmetric functions which are generated by cyclic permutations of the variables in a single monomial was only settled in 2009. This paper studies the much more complicated cubic case for such functions. A new concept of \\emph{patterns} is introduced, by means of which the structure of the smallest group G_n, whose action on the set of all such cubic functions in $n$ variables gives the affine equivalence classes for these functions under permutation of the variables, is determined. We conjecture that the equivalence classes are the same if all nonsingular affine transformations, not just permutations, are allowed. This conjecture is verified if n < 22. Our method gives much more information about the equivalence classes; for example, in t...
Distal acquired demyelinating symmetric (DADS) neuropathy associated with colorectal adenocarcinoma.
Ayyappan, Sujith; Day, Timothy; Kiers, Lynette
2015-06-01
Paraneoplastic neuropathies are well recognized as a remote effect of cancer, and subacute sensory neuronopathy is a recognized syndrome. Demyelinating neuropathies are relatively rare. Distal acquired demyelinating symmetric (DADS) neuropathy associated with lymphoproliferative disease has been reported previously. We present the association of DADS neuropathy with solid tumor. We report the clinical presentation, electrophysiology, and progress of DADS neuropathy in a patient later found to have colorectal adenocarcinoma. A patient presented with subacute onset of symmetric distal sensory and motor symptoms. Electrophysiology was typical of DADS neuropathy. Anti-MAG antibodies were initially positive at low titer, and indirect immunofluorescence analysis for anti-nuclear antibodies revealed autoantibodies to centromere nuclear protein-F (CENP-F). There was clinical and electrophysiologic resolution after tumor resection. This case describes the presentation of DADS neuropathy as a paraneoplastic syndrome in a patient later found to have colorectal adenocarcinoma. © 2014 Wiley Periodicals, Inc.
Control of Wind Turbines during Symmetrical and Asymmetrical Grid Faults
DEFF Research Database (Denmark)
Göksu, Ömer
grid code requirements, which are targeting to make the WPPs operate in a closer manner to the conventional power plants. Common to most of the grid codes, WPPs are required to stay connected during short-circuit grid faults, and also inject reactive current in order to support the grid voltage...... regulation. The uninterrupted operation of WPPs is required even when the grid voltage drops down to zero; and the current injection requirement is defined as positive sequence reactive current irrespective of the fault type; symmetrical or asymmetrical. In this project, the response of full-scale converter...... type wind turbines (WTs), in an AC connected WPP, is investigated and control algorithms are designed for minimum disrupted operation and improved grid support, for both symmetrical and asymmetrical grid faults. WTs’ response with conventional control algorithms is studied regarding the impact...
Symmetrical and overloaded effect of diffusion in information filtering
Zhu, Xuzhen; Tian, Hui; Chen, Guilin; Cai, Shimin
2017-10-01
In physical dynamics, mass diffusion theory has been applied to design effective information filtering models on bipartite network. In previous works, researchers unilaterally believe objects' similarities are determined by single directional mass diffusion from the collected object to the uncollected, meanwhile, inadvertently ignore adverse influence of diffusion overload. It in some extent veils the essence of diffusion in physical dynamics and hurts the recommendation accuracy and diversity. After delicate investigation, we argue that symmetrical diffusion effectively discloses essence of mass diffusion, and high diffusion overload should be published. Accordingly, in this paper, we propose an symmetrical and overload penalized diffusion based model (SOPD), which shows excellent performances in extensive experiments on benchmark datasets Movielens and Netflix.
Information Retrieval and Criticality in Parity-Time-Symmetric Systems
Kawabata, Kohei; Ashida, Yuto; Ueda, Masahito
2017-11-01
By investigating information flow between a general parity-time (P T -)symmetric non-Hermitian system and an environment, we find that the complete information retrieval from the environment can be achieved in the P T -unbroken phase, whereas no information can be retrieved in the P T -broken phase. The P T -transition point thus marks the reversible-irreversible criticality of information flow, around which many physical quantities such as the recurrence time and the distinguishability between quantum states exhibit power-law behavior. Moreover, by embedding a P T -symmetric system into a larger Hilbert space so that the entire system obeys unitary dynamics, we reveal that behind the information retrieval lies a hidden entangled partner protected by P T symmetry. Possible experimental situations are also discussed.
PT -symmetric spectral singularity and negative-frequency resonance
Pendharker, Sarang; Guo, Yu; Khosravi, Farhad; Jacob, Zubin
2017-03-01
Vacuum consists of a bath of balanced and symmetric positive- and negative-frequency fluctuations. Media in relative motion or accelerated observers can break this symmetry and preferentially amplify negative-frequency modes as in quantum Cherenkov radiation and Unruh radiation. Here, we show the existence of a universal negative-frequency-momentum mirror symmetry in the relativistic Lorentzian transformation for electromagnetic waves. We show the connection of our discovered symmetry to parity-time (PT ) symmetry in moving media and the resulting spectral singularity in vacuum fluctuation-related effects. We prove that this spectral singularity can occur in the case of two metallic plates in relative motion interacting through positive- and negative-frequency plasmonic fluctuations (negative-frequency resonance). Our work paves the way for understanding the role of PT -symmetric spectral singularities in amplifying fluctuations and motivates the search for PT symmetry in novel photonic systems.
PT-symmetric ladders with a scattering core
Energy Technology Data Exchange (ETDEWEB)
D' Ambroise, J. [Department of Mathematics, Amherst College, Amherst, MA 01002-5000 (United States); Lepri, S. [CNR – Consiglio Nazionale delle Ricerche, Istituto dei Sistemi Complessi, via Madonna del piano 10, I-50019 Sesto Fiorentino (Italy); Istituto Nazionale di Fisica Nucleare, Sezione di Firenze, via G. Sansone 1, I-50019 Sesto Fiorentino (Italy); Malomed, B.A. [Department of Physical Electronics, School of Electrical Engineering, Faculty of Engineering, Tel Aviv University, Tel Aviv 69978 (Israel); Kevrekidis, P.G. [Department of Mathematics and Statistics, University of Massachusetts, Amherst, MA 01003-9305 (United States)
2014-08-01
We consider a PT-symmetric chain (ladder-shaped) system governed by the discrete nonlinear Schrödinger equation where the cubic nonlinearity is carried solely by two central “rungs” of the ladder. Two branches of scattering solutions for incident plane waves are found. We systematically construct these solutions, analyze their stability, and discuss non-reciprocity of the transmission associated with them. To relate the results to finite-size wavepacket dynamics, we also perform direct simulations of the evolution of the wavepackets, which confirm that the transmission is indeed asymmetric in this nonlinear system with the mutually balanced gain and loss. - Highlights: • We model a PT-symmetric ladder system with cubic nonlinearity on two central rungs. • We examine non-reciprocity and stability of incident plane waves. • Simulations of wavepackets confirm our results.
PT-Symmetric Real Dirac Fermions and Semimetals.
Zhao, Y X; Lu, Y
2017-02-03
Recently, Weyl fermions have attracted increasing interest in condensed matter physics due to their rich phenomenology originated from their nontrivial monopole charges. Here, we present a theory of real Dirac points that can be understood as real monopoles in momentum space, serving as a real generalization of Weyl fermions with the reality being endowed by the PT symmetry. The real counterparts of topological features of Weyl semimetals, such as Nielsen-Ninomiya no-go theorem, 2D subtopological insulators, and Fermi arcs, are studied in the PT symmetric Dirac semimetals and the underlying reality-dependent topological structures are discussed. In particular, we construct a minimal model of the real Dirac semimetals based on recently proposed cold atom experiments and quantum materials about PT symmetric Dirac nodal line semimetals.
Synthesis of novel symmetrical macrocycle via oxidative homocoupling of bisalkyne
Energy Technology Data Exchange (ETDEWEB)
Kamalulazmy, Nurulain; Hassan, Nurul Izzaty [School of Chemical Sciences and Food Technology, Universiti Kebangsaan Malaysia, 43600 UKM Bangi, Selangor Darul Ehsan (Malaysia)
2014-09-03
A novel symmetrical macrocycle has been synthesised via oxidative homocoupling of bisalkyne, diprop-2-ynyl pyridine-2,6-dicarboxylate mediated by copper (I) iodide (CuI) and 4-dimethylaminopyridine (DMAP). The precursor compound was synthesised from 2,6-pyridine dicarbonyl dichloride and propargyl alcohol in the presence of triethylamine. The reaction mixture was stirred overnight and further purified via column chromatograpy with 76% yield. Single crystal for X-ray study was obtained by recrystallization from acetone. Subsequently, a symmetrical macrocycle was synthesised from oxidative homocoupling of precursor compound in open atmosphere. The crude product was purified by column chromatography to furnish macrocycle compound with 5% yield. Both compounds were characterised by IR, {sup 1}H and {sup 13}C NMR and mass spectral techniques. The unusual conformation of the bisalkyne and twisted conformation of designed macrocycle has influence the percentage yield. This has been studied thoroughly by X-ray crystallography and electronic structure calculations.
Color symmetrical superconductivity in a schematic nuclear quark model
DEFF Research Database (Denmark)
Bohr, Henrik; Providencia, C.; da Providencia, J.
2010-01-01
In this letter, a novel BCS-type formalism is constructed in the framework of a schematic QCD inspired quark model, having in mind the description of color symmetrical superconducting states. In the usual approach to color superconductivity, the pairing correlations affect only the quasi-particle......In this letter, a novel BCS-type formalism is constructed in the framework of a schematic QCD inspired quark model, having in mind the description of color symmetrical superconducting states. In the usual approach to color superconductivity, the pairing correlations affect only the quasi...... charge is automatically insured. We stress that the present note is concerned with the description of quark matter in terms of effective models, such as the NJL model, which are solely expressed in terms of fermion operators, so that in them the gluonic gauge fields are not present....
Parametric comparison of EMDS algorithm with some symmetric cryptosystems
Directory of Open Access Journals (Sweden)
Mani Arora
2017-07-01
Full Text Available Over the last decades owing to the incredible boost in the electronics industry and wireless technology, there has been an extraordinary outburst in the extent of digital data transmitted via the internet by means of handheld chic devices. The hefty amount of transmitted data requires data to be safe and sound in addition to transmission speed should be swift. In this document we have prepared qualitatively cryptanalysis of our proposed technique ’EMDS’ and evaluated against it with further preferred symmetric algorithms. We have analyzed the diverse variety of symmetric algorithms by following the tangible approach and examined dissimilar parameters implicated. This document endows with estimation of ten of the majority of frequent algorithms. A contrast has been carried out connecting those algorithms and EMDS based on diverse parameters.
Faraoni, Valerio
2013-01-01
This book offers an essential bridge between college-level introductions and advanced graduate-level books on special relativity. It begins at an elementary level, presenting and discussing the basic concepts normally covered in college-level works, including the Lorentz transformation. Subsequent chapters introduce the four-dimensional worldview implied by the Lorentz transformations, mixing time and space coordinates, before continuing on to the formalism of tensors, a topic usually avoided in lower-level courses. The book’s second half addresses a number of essential points, including the concept of causality; the equivalence between mass and energy, including applications; relativistic optics; and measurements and matter in Minkowski spacetime. The closing chapters focus on the energy-momentum tensor of a continuous distribution of mass-energy and its covariant conservation; angular momentum; a discussion of the scalar field of perfect fluids and the Maxwell field; and general coordinates. Every chapter...
Association du personnel
2011-01-01
Are you a member of the Staff Association? Did you know that as a member you can benefit from the following special offers: BCGE (Banque Cantonale de Genève): personalized banking solutions with preferential conditions. TPG: reduced rates on annual transport passes for active and retired staff. Aquaparc: reduced ticket prices for children and adults at this Swiss waterpark in Le Bouveret. Walibi: reduced prices for children and adults at this French attraction park in Les Avenières. FNAC: 5% reduction on FNAC vouchers. For more information about all these offers, please consult our web site: http://association.web.cern.ch/association/en/OtherActivities/Offers.html
Staff Association
2011-01-01
Are you a member of the Staff Association? Did you know that as a member you can benefit from the following special offers: BCGE (Banque Cantonale de Genève): personalized banking solutions with preferential conditions. TPG: reduced rates on annual transport passes for all active and retired staff. Aquaparc: reduced ticket prices for children and adults at this Swiss waterpark in Le Bouveret. Walibi: reduced prices for children and adults at this French attraction park in Les Avenières. FNAC: 5% reduction on FNAC vouchers. For more information about all these offers, please consult our web site: http://association.web.cern.ch/association/en/OtherActivities/Offers.html
2007-01-01
A special wide-load convoy will affect traffic between Hall 180 (Meyrin site) and Point 1 (ATLAS) on Tuesday 29 May. The following measures will be in place: Partial closure of Route Arago and Route Einstein between 9.00 a.m. and 12 midday, depending on the rate at which the convoy advances. Closure of Route Einstein between 12 and 2.00 p.m. between Building 104 and Route Veksler (see diagram). Closure of Entrance B in both directions between 12 and 2.30 p.m. Please use Entrance A. For safety reasons, cyclists and pedestrians will not be allowed to ride or walk alongside the convoy. Please comply with the instructions given by the convoy officers. TS-IC Group (tel : 160319 - 163012)
A Fully Symmetric and Completely Decoupled MEMS-SOI Gyroscope
Abdelhameed SHARAF; Sherif SEDKY; Mohamed SERRY; Amro ELSHURAFA; Mahmoud ASHOUR; S. E.-D. HABIB
2011-01-01
This paper introduces a novel MEMS gyroscope that is capable of exciting the drive mode differentially. The structure also decouples the drive and sense modes via an intermediate mass and decoupling beams. Both drive and sense modes are fully differential enabling control over the zero-rate-output for the former and maximizing output sensitivity using a bridge circuit for the latter. Further, the structure is fully symmetric about the x- and y- axes which results in minimizing the temperature...
Bound Electron States in Skew-symmetric Quantum Wire Intersections
2014-01-01
for electronic transport studies was to confine resonant- tunneling heterostructures laterally with a fabrication-imposed po- tential. This approach...Research Office P.O. Box 12211 Research Triangle Park, NC 27709-2211 Quantum Wires, Crossed Nanowires , Trapped Electron States, Quantum Dots REPORT...realistic systems such as semiconductor nanowire films and carbon nanotube bundles. Bound electron states in skew-symmetric quantum wire intersections by
Mechanisms and Management of Diabetic Painful Distal Symmetrical Polyneuropathy
Tesfaye, Solomon; Boulton, Andrew J.M.; Dickenson, Anthony H.
2013-01-01
Although a number of the diabetic neuropathies may result in painful symptomatology, this review focuses on the most common: chronic sensorimotor distal symmetrical polyneuropathy (DSPN). It is estimated that 15–20% of diabetic patients may have painful DSPN, but not all of these will require therapy. In practice, the diagnosis of DSPN is a clinical one, whereas for longitudinal studies and clinical trials, quantitative sensory testing and electrophysiological assessment are usually necessary...
The relativistic Boltzmann equation on a spherically symmetric gravitational field
Takou, Etienne; Ciake Ciake, Fidèle L.
2017-10-01
In this paper, we consider the Cauchy problem for the relativistic Boltzmann equation with near vacuum initial data where the distribution function depends on the time, the position and the impulsion. We consider this equation on a spherically symmetric gravitational field spacetime. The collision kernel considered here is for the hard potentials case. We prove the existence of a unique global (in time) mild solution in a suitable weighted space.
Singularity in Gravitational Collapse of Plane Symmetric Charged Vaidya Spacetime
Sharif, M
2010-01-01
We study the final outcome of gravitational collapse resulting from the plane symmetric charged Vaidya spacetime. Using the field equations, we show that the weak energy condition is always satisfied by collapsing fluid. It is found that the singularity formed is naked. The strength of singularity is also investigated by using Nolan's method. This turns out to be a strong curvature singularity in Tipler's sense and hence provides a counter example to the cosmic censorship hypothesis.
Procrustes Problems for General, Triangular, and Symmetric Toeplitz Matrices
Directory of Open Access Journals (Sweden)
Juan Yang
2013-01-01
Full Text Available The Toeplitz Procrustes problems are the least squares problems for the matrix equation AX=B over some Toeplitz matrix sets. In this paper the necessary and sufficient conditions are obtained about the existence and uniqueness for the solutions of the Toeplitz Procrustes problems when the unknown matrices are constrained to the general, the triangular, and the symmetric Toeplitz matrices, respectively. The algorithms are designed and the numerical examples show that these algorithms are feasible.
Cylindrically symmetric cosmological model in the presence of bulk ...
Indian Academy of Sciences (India)
2016-09-06
Sep 6, 2016 ... (2016) 87: 47 c Indian Academy of Sciences. DOI 10.1007/s12043-016-1235-5. Cylindrically symmetric cosmological model in the presence of bulk stress with varying. V G METE1,∗, A S NIMKAR2 and V D ELKAR3. 1Department of Mathematics, R.D.I.K. & K.D. College, Badnera-Amravati 444 701, India.
Braneworld Inflation in Supergravity with a Shift Symmetric K $\\"{a ...
Indian Academy of Sciences (India)
We propose a new solution to the η -problem in supergravity using a shift symmetric K\\"{a}hler potential in the context of the Randall–Sundrum type II model. We focus on a F-term supergravity inflation with a minimal K\\"{a}hler potential taking into account the radiative corrections. The slow-roll conditions are ensured by the ...
Unidirectional Invisibility induced by PT-Symmetric Periodic Structures
Lin, Zin; Ramezani, Hamidreza; Eichelkraut, Toni; Kottos, Tsampikos; Cao, Hui; Christodoulides, Demetrios N.
2011-01-01
We show that parity-time (PT) symmetric Bragg periodic structures, near the spontaneous PT - symmetry breaking point, can act as unidirectional invisible media. In this regime, the re flection from one end is diminished while it is enhanced from the other. At the same time the transmission coefficient and phase, are indistinguishable from those expected in the absence of a grating. The phenomenon is robust even in the presence of Kerr non-linearities, and it can also effectively suppress opti...
Engineering wavefront caustics trajectories in ${\\cal PT}$-symmetric lattices
Bender, Nicholas; Kottos, Tsampikos
2015-01-01
We utilize caustic theory in ${\\cal PT}-$symmetric lattices to design focusing and curved beam dynamics. We show that the gain and loss parameter in these systems provides an addition degree of freedom which allows for the design of the same caustics trajectories with different intensity distribution in the individual waveguides. Moreover we can create aberration-free focal points at any paraxial distance $z_f$, with anomalously large focal intensity.
The Phase Space Formulation of Time-Symmetric Quantum Mechanics
Directory of Open Access Journals (Sweden)
Charlyne de Gosson
2015-11-01
Full Text Available Time-symmetric quantum mechanics can be described in the Weyl–Wigner–Moyal phase space formalism by using the properties of the cross-terms appearing in the Wigner distribution of a sum of states. These properties show the appearance of a strongly oscillating interference between the pre-selected and post-selected states. It is interesting to note that the knowledge of this interference term is sufficient to reconstruct both states. Quanta 2015; 4: 27–34.
${ \\mathcal P }{ \\mathcal T }$-symmetric interpretation of unstable effective potentials
Bender, Carl M.; Mavromatos, Nick E.; Sarkar, Sarben
2016-01-01
The conventional interpretation of the one-loop effective potentials of the Higgs field in the Standard Model and the gravitino condensate in dynamically broken supergravity is that these theories are unstable at large field values. A ${ \\mathcal P }{ \\mathcal T }$-symmetric reinterpretation of these models at a quantum-mechanical level eliminates these instabilities and suggests that these instabilities may also be tamed at the quantum-field-theory level.
New Classes of Quasi-helically Symmetric Stellarators
Energy Technology Data Exchange (ETDEWEB)
L.P. Ku and A.H. Boozer
2010-08-09
New classes of quasi-helically symmetric stellarators with aspect ratios ≤ 10 have been found which are stable to the perturbation of magnetohydrodynamic modes at plasma pressures of practical interest. These configurations have large rotational transform and good quality of flux surfaces. Characteristics of some selected examples are discussed in detail. The feasibility of using modular coils for these stellarators has been investigated. It is shown that practical designs for modular coils can be achieved.
Vibrational motion in a symmetric, double minimum potential
DEFF Research Database (Denmark)
Spanget-Larsen, Jens
2015-01-01
Molecular vibrational motion in a symmetric, double minimum potential is treated by means of a quartic model potential, by reference to the tables published by Jaan Laane and the results of harmonic analyses for the stationary points. The inversion vibration of ammonia is treated in detail. - Not...... on the harmonic approximation for polyatomic molecules are appended. - Presented at a NORFA Workshop in Hirtshals, Denmark, August 1997....
Noncommutative symmetric functions III: Deformations of Cauchy and convolution algebras
Directory of Open Access Journals (Sweden)
Gérard H. E. Duchamp
1997-12-01
Full Text Available This paper discusses various deformations of free associative algebras and of their convolution algebras. Our main examples are deformations of noncommutative symmetric functions related to families of idempotents in descent algebras, and a simple q-analogue of the shuffle product, which has unexpected connections with quantum groups, hyperplane arrangements, and certain questions in mathematical physics (the quon algebra, generalized Brownian motion.
Quasi-homologous spherically symmetric branes and their symmetry breaking
Energy Technology Data Exchange (ETDEWEB)
Abdalla, M.C.B.; Carlesso, P.F. [UNESP - Universidade Estadual Paulista, Instituto de Fisica Teorica, Rua Dr. Bento Teobaldo Ferraz, 271, Bloco II, Barra-Funda, Caixa Postal 70532-2, Sao Paulo, SP (Brazil); Hoff da Silva, J.M. [UNESP - Universidade Estadual Paulista, Departamento de Fisica e Quimica, Guaratingueta, SP (Brazil)
2013-06-15
We revisit the dynamical system-based approach of spherically symmetric vacuum braneworlds, pointing out and studying the existence of a transcritical bifurcation as the dark pressure parameter changes its sign, we analyze some consequences of not discard the brane cosmological constant. For instance, it is noteworthy that the existence of an isothermal state equation between the dark fluid parameters cannot be obtained via the requirement of a quasi-homologous symmetry of the vacuum. (orig.)
On the structure and convergence of the symmetric Zassenhaus formula
Arnal, Ana; Casas, Fernando; Chiralt, Cristina
2017-08-01
We propose and analyze a symmetric version of the Zassenhaus formula for disentangling the exponential of two non-commuting operators. A recursive procedure for generating the expansion up to any order is presented which also allows one to get an enlarged domain of convergence when it is formulated for matrices. It is shown that the approximations obtained by truncating the infinite expansion considerably improve those arising from the standard Zassenhaus formula.
An introduction to spherically symmetric loop quantum gravity black holes
Energy Technology Data Exchange (ETDEWEB)
Gambini, Rodolfo [Instituto de Física, Facultad de Ciencias, Iguá 4-225, esq. Mataojo, 11400 Montevideo (Uruguay); Pullin, Jorge [Department of Physics and Astronomy, Louisiana State University, Baton Rouge, LA 70803-4001 (United States)
2015-03-26
We review recent developments in the treatment of spherically symmetric black holes in loop quantum gravity. In particular, we discuss an exact solution to the quantum constraints that represents a black hole and is free of singularities. We show that new observables that are not present in the classical theory arise in the quantum theory. We also discuss Hawking radiation by considering the quantization of a scalar field on the quantum spacetime.
Twofold Transition in PT-symmetric Coupled Oscillators
2013-12-26
2Dipartimento di Matematica e Fisica Ennio De Giorgi, Università del Salento and I. N. F. N. Sezione di Lecce, Via Arnesano, I-73100 Lecce, Italy...resonators with experimental coupling constant κ . Such a system is PT -symmetric if one resonator has an optically driven gain and the other...resonator has a balanced loss. The experimental setup is shown schematically in Fig. 1. We examine here the properties of the mathematical model on a
Time-symmetric universe model and its observational implication
Energy Technology Data Exchange (ETDEWEB)
Futamase, T.; Matsuda, T.
1987-08-01
A time-symmetric closed-universe model is discussed in terms of the radiation arrow of time. The time symmetry requires the occurrence of advanced waves in the recontracting phase of the Universe. We consider the observational consequences of such advanced waves, and it is shown that a test observer in the expanding phase can observe a time-reversed image of a source of radiation in the future recontracting phase.
Characterizing and approximating eigenvalue sets of symmetric interval matrices
DEFF Research Database (Denmark)
Hladík, Milan; Daney, David; Tsigaridas, Elias
2011-01-01
We consider the eigenvalue problem for the case where the input matrix is symmetric and its entries are perturbed, with perturbations belonging to some given intervals. We present a characterization of some of the exact boundary points, which allows us to introduce an inner approximation algorith......, that in many case estimates exact bounds. To our knowledge, this is the first algorithm that is able to guarantee exactness. We illustrate our approach by several examples and numerical experiments....
Dynamics of entanglement of bosonic modes on symmetric graphs
Ghahari, F.; Karimipour, V.; Shahrokhshahi, R.
2007-04-01
We investigate the dynamics of an initially disentangled Gaussian state on a general finite symmetric graph. As concrete examples we obtain properties of this dynamics on mean field graphs (also called fully connected or complete graphs) of arbitrary sizes. In the same way that chains can be used for transmitting entanglement by their natural dynamics, these graphs can be used to store entanglement. We also consider two kinds of regular polyhedron which show interesting features of entanglement sharing.
Dynamics of entanglement of bosonic modes on symmetric graphs
Energy Technology Data Exchange (ETDEWEB)
Ghahari, F. [Department of Physics, Sharif University of Technology, P.O. Box 11365-9161, Tehran (Iran, Islamic Republic of)]. E-mail: ghaharikermani@mehr.sharif.edu; Karimipour, V. [Department of Physics, Sharif University of Technology, P.O. Box 11365-9161, Tehran (Iran, Islamic Republic of)]. E-mail: vahid@sharif.edu; Shahrokhshahi, R. [Department of Physics, Sharif University of Technology, P.O. Box 11365-9161, Tehran (Iran, Islamic Republic of)]. E-mail: shahrokhshahi@mehr.sharif.edu
2007-04-02
We investigate the dynamics of an initially disentangled Gaussian state on a general finite symmetric graph. As concrete examples we obtain properties of this dynamics on mean field graphs (also called fully connected or complete graphs) of arbitrary sizes. In the same way that chains can be used for transmitting entanglement by their natural dynamics, these graphs can be used to store entanglement. We also consider two kinds of regular polyhedron which show interesting features of entanglement sharing.
Factoring symmetric indefinite matrices on high-performance architectures
Jones, Mark T.; Patrick, Merrell L.
1990-01-01
The Bunch-Kaufman algorithm is the method of choice for factoring symmetric indefinite matrices in many applications. However, the Bunch-Kaufman algorithm does not take advantage of high-performance architectures such as the Cray Y-MP. Three new algorithms, based on Bunch-Kaufman factorization, that take advantage of such architectures are described. Results from an implementation of the third algorithm are presented.
Constrained field theories on spherically symmetric spacetimes with horizons
Fernandes, Karan; Lahiri, Amitabha; Ghosh, Suman
2017-02-01
We apply the Dirac-Bergmann algorithm for the analysis of constraints to gauge theories defined on spherically symmetric black hole backgrounds. We find that the constraints for a given theory are modified on such spacetimes through the presence of additional contributions from the horizon. As a concrete example, we consider the Maxwell field on a black hole background, and determine the role of the horizon contributions on the dynamics of the theory.
Computing approximate (symmetric block) rational Krylov subspaces without explicit inversion
Mach, Thomas; Pranić, Miroslav S.; Vandebril, Raf
2013-01-01
It has been shown, see TW623, that approximate extended Krylov subspaces can be computed —under certain assumptions— without any explicit inversion or system solves. Instead the necessary products A-1v are obtained in an implicit way retrieved from an enlarged Krylov subspace. In this paper this approach is generalized to rational Krylov subspaces, which contain besides poles at infinite and zero also finite non-zero poles. Also an adaption of the algorithm to the block and the symmetric ...
The heat kernel and Hardy's theorem on symmetric spaces of ...
Indian Academy of Sciences (India)
R. Narasimhan (Krishtel eMaging) 1461 1996 Oct 15 13:05:22
that is, the Plancherel measure is of at most polynomial growth. Let G/K be the Riemannian symmetric space equipped with a G-invariant Riemannian metric and the Laplace–Beltrami operator on G/K. Then there exists a unique family of smooth function ht,t > 0, with the following properties: (i) ht is K-biinvariant, for each t ...
Nonstatic plane-symmetric solutions for Einstein-Maxwell equations
Energy Technology Data Exchange (ETDEWEB)
Hajj-Boutros, J.; Sfeila, J.
1985-11-16
The general solution of the Einstein-Maxwell field equations is obtained under the assumptions that 1) the source of the gravitational field is a charged dust, 2) the space-time is plane-symmetric, 3) the metric is of the form ds/sup 2/ = dt/sup 2/ - exp (2u(t, z)) dz/sup 2/ - Z/sup 2/(z) T/sup 2/(t)(dx/sup 2/ + dy/sup 2/). (orig.).
IDEALS GENERATED BY LINEAR FORMS AND SYMMETRIC ALGEBRAS
Directory of Open Access Journals (Sweden)
Gaetana Restuccia
2016-01-01
Full Text Available We consider ideals generated by linear forms in the variables X1 : : : ;Xn in the polynomial ring R[X1; : : : ;Xn], being R a commutative, Noetherian ring with identity. We investigate when a sequence a1; a2; : : : ; am of linear forms is an ssequence, in order to compute algebraic invariants of the symmetric algebra of the ideal I = (a1; a2; : : : ; am.
Symmetrical, bi-electrode supported solid oxide fuel cell
Cable, Thomas L. (Inventor); Sofie, Stephen W. (Inventor)
2009-01-01
The present invention is a symmetrical bi-electrode supported solid oxide fuel cell comprising a sintered monolithic framework having graded pore electrode scaffolds that, upon treatment with metal solutions and heat subsequent to sintering, acquire respective anodic and cathodic catalytic activity. The invention is also a method for making such a solid oxide fuel cell. The graded pore structure of the graded pore electrode scaffolds in achieved by a novel freeze casting for YSZ tape.
Energetic-electron-driven instability in the helically symmetric experiment.
Deng, C B; Brower, D L; Breizman, B N; Spong, D A; Almagri, A F; Anderson, D T; Anderson, F S B; Ding, W X; Guttenfelder, W; Likin, K M; Talmadge, J N
2009-07-10
Energetic electrons generated by electron cyclotron resonance heating are observed to drive instabilities in the quasihelically symmetric stellarator device. The coherent, global fluctuations peak in the plasma core and are measured in the frequency range of 20-120 kHz. Mode propagation is in the diamagnetic drift direction of the driving species. When quasihelical symmetry is broken, the mode is no longer observed. Experimental observations indicate that the unstable mode is acoustic rather than Alfvénic.
A case of symmetrical lipomatosis of the tongue and a literature review
Energy Technology Data Exchange (ETDEWEB)
Kim, Byung Je; Lee, Eun Joo; Yeo, Soo Hyun; Chang, Hyuk won; Kim, Sang Hyon; Sohn, Sung Il; Lee, Sang Kwon [Keimyung University College of Medicine, Dongsan Medical Center, Daegu (Korea, Republic of)
2013-09-15
Symmetrical lipomatosis of the tongue is an extremely rare condition. To date, few cases have been reported in the literature. Symmetrical lipomatosis remains controversial as to whether it is identical to benign symmetrical lipomatosis or not. We present an extremely rare case of symmetrical lipomatosis of the tongue in a 77-year-old male. We reviewed the literature and discussed the clinical characteristics as well as the role of imaging studies of this disease.
Natalie 2.0: Sparse Global Network Alignment as a Special Case of Quadratic Assignment
Directory of Open Access Journals (Sweden)
Mohammed El-Kebir
2015-11-01
Full Text Available Data on molecular interactions is increasing at a tremendous pace, while the development of solid methods for analyzing this network data is still lagging behind. This holds in particular for the field of comparative network analysis, where one wants to identify commonalities between biological networks. Since biological functionality primarily operates at the network level, there is a clear need for topology-aware comparison methods. We present a method for global network alignment that is fast and robust and can flexibly deal with various scoring schemes taking both node-to-node correspondences as well as network topologies into account. We exploit that network alignment is a special case of the well-studied quadratic assignment problem (QAP. We focus on sparse network alignment, where each node can be mapped only to a typically small subset of nodes in the other network. This corresponds to a QAP instance with a symmetric and sparse weight matrix. We obtain strong upper and lower bounds for the problem by improving a Lagrangian relaxation approach and introduce the open source software tool Natalie 2.0, a publicly available implementation of our method. In an extensive computational study on protein interaction networks for six different species, we find that our new method outperforms alternative established and recent state-of-the-art methods.
Continuous-time symmetric Hopfield nets are computationally universal.
Síma, Jirí; Orponen, Pekka
2003-03-01
We establish a fundamental result in the theory of computation by continuous-time dynamical systems by showing that systems corresponding to so-called continuous-time symmetric Hopfield nets are capable of general computation. As is well known, such networks have very constrained Lyapunov-function controlled dynamics. Nevertheless, we show that they are universal and efficient computational devices, in the sense that any convergent synchronous fully parallel computation by a recurrent network of n discrete-time binary neurons, with in general asymmetric coupling weights, can be simulated by a symmetric continuous-time Hopfield net containing only 18n + 7 units employing the saturated-linear activation function. Moreover, if the asymmetric network has maximum integer weight size w(max) and converges in discrete time t*, then the corresponding Hopfield net can be designed to operate in continuous time Theta(t*/epsilon) for any epsilon > 0 such that w(max)2(12n) computation models, our result implies that any polynomially space-bounded Turing machine can be simulated by a family of polynomial-size continuous-time symmetric Hopfield nets.
Review on symmetric structures in ductile shear zones
Mukherjee, Soumyajit
2017-07-01
Symmetric structures in ductile shear zones range widely in shapes and geneses. Matrix rheology, its flow pattern, its competency contrast with the clast, degree of slip of the clast, shear intensity and its variation across shear zone and deformation temperature, and degree of confinement of clast in shear zones affects (independently) the degree of symmetry of objects. Kinematic vorticity number is one of the parameters that govern tail geometry across clasts. For example, symmetric and nearly straight tails develop if the clast-matrix system underwent dominantly a pure shear/compression. Prolonged deformation and concomitant recrystallization can significantly change the degree of symmetry of clasts. Angular relation between two shear zones or between a shear zone and anisotropy determines fundamentally the degree of symmetry of lozenges. Symmetry of boudinaged clasts too depends on competency contrast between the matrix and clast in some cases, and on the degrees of slip of inter-boudin surfaces and pure shear. Parasitic folds and post-tectonic veins are usually symmetric.
Development of Wireless Endoscope with Symmetrical Motion Characteristics
Directory of Open Access Journals (Sweden)
Jian Guo
2014-09-01
Full Text Available In the biomedical field, a wireless microrobot in a pipe which can move smoothly in water or other aqueous mediums has been urgently demanded. In this paper, several methods of designing a novel microrobot with symmetrical motion characteristics have been discussed and a new kind of wireless microrobot has been developed. According to the modelling analysis, we considered two kinds of common cases occurring in vertical motion, which required gravity compensation. Based on two groups of simulations and experiments on forward-backward motion, upward-downward motion and inclined plane motion, the results and dynamic error evaluation indicated that the wireless microrobot with symmetrical structure could realize similar kinematic characteristics in the horizontal motion. The gravity compensation played an important role in the design process, and the performance of the vertical motion had been improved by gravity compensation. With this method, we made the wireless microrobot realize symmetrical motion characteristics, and simplified the control strategies. Finally, a control panel for our system was designed, which could control the current motion states more intuitively and far more easily through the buttons. The developed wireless microrobot would be very useful in the industrial application and microsurgery application.
Changes in perceived egocentric direction during symmetric vergence.
Sridhar, Deepika; Bedell, Harold E
2013-01-01
The Wells-Hering's laws of perceived egocentric visual direction (EVD) assume that information about eye position includes equal contributions from both eyes. An implication of this assumption is that only versional eye movements should lead to a change in perceived EVD. Previously, we showed that a differential weighting of eye-position information occurs in some individuals during asymmetric vergence. To extend this finding, we determined here whether a differential weighting of eye-position information occurs also during symmetric vergence eye movements. Open-loop pointing responses to a bright target were obtained in five subjects to estimate the contribution of each eye's position information to perceived EVD during symmetric vergence demands that ranged from 6 prism diopters base in to 18 prism diopters base out. In all five subjects, the slopes of the lines fit to the pointing responses were in the direction that was predicted from an unequal weighting of eye-position information. We conclude that symmetric vergence movements can result in a change in perceived visual direction, contrary to an assumption of the Wells-Hering's laws.
Understanding Symmetric Smoothing Filters: A Gaussian Mixture Model Perspective
Chan, Stanley H.; Zickler, Todd; Lu, Yue M.
2017-11-01
Many patch-based image denoising algorithms can be formulated as applying a smoothing filter to the noisy image. Expressed as matrices, the smoothing filters must be row normalized so that each row sums to unity. Surprisingly, if we apply a column normalization before the row normalization, the performance of the smoothing filter can often be significantly improved. Prior works showed that such performance gain is related to the Sinkhorn-Knopp balancing algorithm, an iterative procedure that symmetrizes a row-stochastic matrix to a doubly-stochastic matrix. However, a complete understanding of the performance gain phenomenon is still lacking. In this paper, we study the performance gain phenomenon from a statistical learning perspective. We show that Sinkhorn-Knopp is equivalent to an Expectation-Maximization (EM) algorithm of learning a Gaussian mixture model of the image patches. By establishing the correspondence between the steps of Sinkhorn-Knopp and the EM algorithm, we provide a geometrical interpretation of the symmetrization process. This observation allows us to develop a new denoising algorithm called Gaussian mixture model symmetric smoothing filter (GSF). GSF is an extension of the Sinkhorn-Knopp and is a generalization of the original smoothing filters. Despite its simple formulation, GSF outperforms many existing smoothing filters and has a similar performance compared to several state-of-the-art denoising algorithms.
Testing whether and when abstract symmetric patterns produce affective responses.
Directory of Open Access Journals (Sweden)
Marco Bertamini
Full Text Available Symmetry has a central role in visual art, it is often linked to beauty, and observers can detect it efficiently in the lab. We studied what kind of fast and automatic responses are generated by visual presentation of symmetrical patterns. Specifically, we tested whether a brief presentation of novel symmetrical patterns engenders positive affect using a priming paradigm. The abstract patterns were used as primes in a pattern-word interference task. To ensure that familiarity was not a factor, no pattern and no word was ever repeated within each experiment. The task was to classify words that were selected to have either positive or negative valence. We tested irregular patterns, patterns containing vertical and horizontal reflectional symmetry, and patterns containing a 90 deg rotation. In a series of 7 experiments we found that the effect of affective congruence was present for both types of regularity but only when observers had to classify the regularity of the pattern after responding to the word. The findings show that processing abstract symmetrical shapes or random pattern can engender positive or negative affect as long as the regularity of the pattern is a feature that observers have to attend to and classify.
Bright Solitons in a PT-Symmetric Chain of Dimers
Directory of Open Access Journals (Sweden)
Omar B. Kirikchi
2016-01-01
Full Text Available We study the existence and stability of fundamental bright discrete solitons in a parity-time- (PT- symmetric coupler composed by a chain of dimers that is modelled by linearly coupled discrete nonlinear Schrödinger equations with gain and loss terms. We use a perturbation theory for small coupling between the lattices to perform the analysis, which is then confirmed by numerical calculations. Such analysis is based on the concept of the so-called anticontinuum limit approach. We consider the fundamental onsite and intersite bright solitons. Each solution has symmetric and antisymmetric configurations between the arms. The stability of the solutions is then determined by solving the corresponding eigenvalue problem. We obtain that both symmetric and antisymmetric onsite mode can be stable for small coupling, in contrast to the reported continuum limit where the antisymmetric solutions are always unstable. The instability is either due to the internal modes crossing the origin or the appearance of a quartet of complex eigenvalues. In general, the gain-loss term can be considered parasitic as it reduces the stability region of the onsite solitons. Additionally, we analyse the dynamic behaviour of the onsite and intersite solitons when unstable, where typically it is either in the form of travelling solitons or soliton blow-ups.
Understanding Symmetric Smoothing Filters: A Gaussian Mixture Model Perspective.
Chan, Stanley H; Zickler, Todd; Lu, Yue M
2017-11-01
Many patch-based image denoising algorithms can be formulated as applying a smoothing filter to the noisy image. Expressed as matrices, the smoothing filters must be row normalized, so that each row sums to unity. Surprisingly, if we apply a column normalization before the row normalization, the performance of the smoothing filter can often be significantly improved. Prior works showed that such performance gain is related to the Sinkhorn-Knopp balancing algorithm, an iterative procedure that symmetrizes a row-stochastic matrix to a doubly stochastic matrix. However, a complete understanding of the performance gain phenomenon is still lacking. In this paper, we study the performance gain phenomenon from a statistical learning perspective. We show that Sinkhorn-Knopp is equivalent to an expectation-maximization (EM) algorithm of learning a Gaussian mixture model of the image patches. By establishing the correspondence between the steps of Sinkhorn-Knopp and the EM algorithm, we provide a geometrical interpretation of the symmetrization process. This observation allows us to develop a new denoising algorithm called Gaussian mixture model symmetric smoothing filter (GSF). GSF is an extension of the Sinkhorn-Knopp and is a generalization of the original smoothing filters. Despite its simple formulation, GSF outperforms many existing smoothing filters and has a similar performance compared with several state-of-the-art denoising algorithms.
Symmetric Moeller/Bhabha luminosity monitor for the OLYMPUS experiment
Energy Technology Data Exchange (ETDEWEB)
Perez Benito, Roberto [Johannes Gutenberg Universitaet Mainz (Germany); Collaboration: OLYMPUS-Collaboration
2013-07-01
Recent determinations of the proton electric to magnetic form factor ratio indicate an unexpected discrepancy between the ratio obtained using polarisation transfer measurements and the ratio from the Rosenbluth separation technique in unpolarised cross section measurements. This discrepancy has been explained theoretically as the effect of two-photon exchange. The OLYMPUS experiment at DESY proposed to measure the ratio of positron-proton and electron-proton elastic scattering cross sections. The experiment utilised beams of electrons and positrons in the DORIS ring at 2.0 GeV incident on an unpolarized internal hydrogen gas target and the BLAST detector from the MIT-Bates Linear Accelerator Center with modest upgrades. In order to reduce the systematic error from the determination of luminosity, redundant measurements of the relative luminosity were necessary. The symmetric Moeller/Bhabha luminosity monitor built at the University of Mainz consisted of two symmetric arrays of lead fluoride (PbF{sub 2}) crystals. Results on the performance of the symmetric Moeller/Bhabha luminosity monitor are presented in this contribution.
Lee, Myoung-Jae; Jung, Young-Dae
2017-12-01
The dispersion relation for electrostatic Hasegawa surface wave propagating on the interface of a cold dusty plasma slab whose constituents are collisional electrons, collisional streaming ions and dust grains is derived. We have found that there exist high- and low-frequency branches for both symmetric and anti-symmetric modes in the plasma slab. The real frequency of the wave is found to decrease as the ion collision frequency increases for both modes. In the case of the low-frequency branch, the phase velocity of the Hasegawa surface wave in a slab is always faster (slower) than that in a semi-bounded plasma for symmetric mode (anti-symmetric mode). We also found that the Hasegawa surface waves can be damped by the collisional dissipation. However, the characteristic of damping is quite different for the two modes: the magnitude of damping rate for symmetric (anti-symmetric) mode increases (decreases) as the slab thickness decreases.
Directory of Open Access Journals (Sweden)
Farhad Ali
2016-08-01
Full Text Available In this paper we find the Noether symmetries of the Lagrangian of cylindrically symmetric static spacetimes. Using this approach we recover all cylindrically symmetric static spacetimes appeared in the classification by isometries and homotheties. We give different classes of cylindrically symmetric static spacetimes along with the Noether symmetries of the corresponding Lagrangians and conservation laws.
Some Basic Properties of Uniformly Symmetrically Continuous (Real Valued) Functions on Metric Spaces
Manuharawati; Yunianti, D. N.; Jakfar, M.
2018-01-01
We give the definition of uniform symmetric continuity for real valued functions defined on a metric space. Then we investigate the basic properties of uniformly symmetrically continuous functions and compare them with those of symmetrically continuous functions and uniformly continuous functions. Several examples are also given.
Support Schemes and Ownership Structures
DEFF Research Database (Denmark)
Ropenus, Stephanie; Schröder, Sascha Thorsten; Costa, Ana
for promoting combined heat and power and energy from renewable sources. These Directives are to be implemented at the national level by the Member States. Section 3 conceptually presents the spectrum of national support schemes, ranging from investment support to market‐based operational support. The choice...... an introduction to the policy context for mCHP. Section 1 describes the rationale for the promotion of mCHP by explaining its potential contribution to European energy policy goals. Section 2 addresses the policy context at the supranational European level by outlining relevant EU Directives on support schemes......In recent years, fuel cell based micro‐combined heat and power has received increasing attention due to its potential contribution to energy savings, efficiency gains, customer proximity and flexibility in operation and capacity size. The FC4Home project assesses technical and economic aspects...
Network Regulation and Support Schemes
DEFF Research Database (Denmark)
Ropenus, Stephanie; Schröder, Sascha Thorsten; Jacobsen, Henrik
2009-01-01
-in tariffs to market-based quota systems, and network regulation approaches, comprising rate-of-return and incentive regulation. National regulation and the vertical structure of the electricity sector shape the incentives of market agents, notably of distributed generators and network operators....... This article seeks to investigate the interactions between the policy dimensions of support schemes and network regulation and how they affect the deployment of distributed generation. Firstly, a conceptual analysis examines how the incentives of the different market agents are affected. In particular......At present, there exists no explicit European policy framework on distributed generation. Various Directives encompass distributed generation; inherently, their implementation is to the discretion of the Member States. The latter have adopted different kinds of support schemes, ranging from feed...
Subranging scheme for SQUID sensors
Penanen, Konstantin I. (Inventor)
2008-01-01
A readout scheme for measuring the output from a SQUID-based sensor-array using an improved subranging architecture that includes multiple resolution channels (such as a coarse resolution channel and a fine resolution channel). The scheme employs a flux sensing circuit with a sensing coil connected in series to multiple input coils, each input coil being coupled to a corresponding SQUID detection circuit having a high-resolution SQUID device with independent linearizing feedback. A two-resolution configuration (course and fine) is illustrated with a primary SQUID detection circuit for generating a fine readout, and a secondary SQUID detection circuit for generating a course readout, both having feedback current coupled to the respective SQUID devices via feedback/modulation coils. The primary and secondary SQUID detection circuits function and derive independent feedback. Thus, the SQUID devices may be monitored independently of each other (and read simultaneously) to dramatically increase slew rates and dynamic range.
An efficient compression scheme for bitmap indices
Energy Technology Data Exchange (ETDEWEB)
Wu, Kesheng; Otoo, Ekow J.; Shoshani, Arie
2004-04-13
When using an out-of-core indexing method to answer a query, it is generally assumed that the I/O cost dominates the overall query response time. Because of this, most research on indexing methods concentrate on reducing the sizes of indices. For bitmap indices, compression has been used for this purpose. However, in most cases, operations on these compressed bitmaps, mostly bitwise logical operations such as AND, OR, and NOT, spend more time in CPU than in I/O. To speedup these operations, a number of specialized bitmap compression schemes have been developed; the best known of which is the byte-aligned bitmap code (BBC). They are usually faster in performing logical operations than the general purpose compression schemes, but, the time spent in CPU still dominates the total query response time. To reduce the query response time, we designed a CPU-friendly scheme named the word-aligned hybrid (WAH) code. In this paper, we prove that the sizes of WAH compressed bitmap indices are about two words per row for large range of attributes. This size is smaller than typical sizes of commonly used indices, such as a B-tree. Therefore, WAH compressed indices are not only appropriate for low cardinality attributes but also for high cardinality attributes.In the worst case, the time to operate on compressed bitmaps is proportional to the total size of the bitmaps involved. The total size of the bitmaps required to answer a query on one attribute is proportional to the number of hits. These indicate that WAH compressed bitmap indices are optimal. To verify their effectiveness, we generated bitmap indices for four different datasets and measured the response time of many range queries. Tests confirm that sizes of compressed bitmap indices are indeed smaller than B-tree indices, and query processing with WAH compressed indices is much faster than with BBC compressed indices, projection indices and B-tree indices. In addition, we also verified that the average query response time
Supporting Argumentation Schemes in Argumentative Dialogue Games
Directory of Open Access Journals (Sweden)
Wells Simon
2014-03-01
Full Text Available This paper reports preliminary work into the exploitation of argumentation schemes within dialogue games. We identify a property of dialogue games that we call “scheme awareness” that captures the relationship between dialogue game systems and argumentation schemes. Scheme awareness is used to examine the ways in which existing dialogue games utilise argumentation schemes and consequently the degree with which a dialogue game can be used to construct argument structures. The aim is to develop a set of guidelines for dialogue game design, which feed into a set of Dialogue Game Description Language (DGDL extensions in turn enabling dialogue games to better exploit argumentation schemes.
An Arbitrated Quantum Signature Scheme without Entanglement*
Li, Hui-Ran; Luo, Ming-Xing; Peng, Dai-Yuan; Wang, Xiao-Jun
2017-09-01
Several quantum signature schemes are recently proposed to realize secure signatures of quantum or classical messages. Arbitrated quantum signature as one nontrivial scheme has attracted great interests because of its usefulness and efficiency. Unfortunately, previous schemes cannot against Trojan horse attack and DoS attack and lack of the unforgeability and the non-repudiation. In this paper, we propose an improved arbitrated quantum signature to address these secure issues with the honesty arbitrator. Our scheme takes use of qubit states not entanglements. More importantly, the qubit scheme can achieve the unforgeability and the non-repudiation. Our scheme is also secure for other known quantum attacks.
A biometric signcryption scheme without bilinear pairing
Wang, Mingwen; Ren, Zhiyuan; Cai, Jun; Zheng, Wentao
2013-03-01
How to apply the entropy in biometrics into the encryption and remote authentication schemes to simplify the management of keys is a hot research area. Utilizing Dodis's fuzzy extractor method and Liu's original signcryption scheme, a biometric identity based signcryption scheme is proposed in this paper. The proposed scheme is more efficient than most of the previous proposed biometric signcryption schemes for that it does not need bilinear pairing computation and modular exponentiation computation which is time consuming largely. The analysis results show that under the CDH and DL hard problem assumption, the proposed scheme has the features of confidentiality and unforgeability simultaneously.
Quantum gauge freedom in very special relativity
Directory of Open Access Journals (Sweden)
Sudhaker Upadhyay
2017-02-01
Full Text Available We demonstrate Yokoyama gaugeon formalism for the Abelian one-form gauge (Maxwell as well as for Abelian two-form gauge theory in the very special relativity (VSR framework. In VSR scenario, the extended action due to introduction of gaugeon fields also possesses form invariance under quantum gauge transformations. It is observed that the gaugeon field together with gauge field naturally acquire mass, which is different from the conventional Higgs mechanism. The quantum gauge transformation implements a shift in gauge parameter. Further, we analyze the BRST symmetric gaugeon formalism in VSR which embeds only one subsidiary condition rather than two.
Quantum gauge freedom in very special relativity
Energy Technology Data Exchange (ETDEWEB)
Upadhyay, Sudhaker, E-mail: sudhakerupadhyay@gmail.com [Centre for Theoretical Studies, Indian Institute of Technology Kharagpur, Kharagpur-721302, West Bengal (India); Panigrahi, Prasanta K., E-mail: pprasanta@iiserkol.ac.in [Indian Institute of Science Education and Research Kolkata, Mohanpur 741246, West Bengal (India)
2017-02-15
We demonstrate Yokoyama gaugeon formalism for the Abelian one-form gauge (Maxwell) as well as for Abelian two-form gauge theory in the very special relativity (VSR) framework. In VSR scenario, the extended action due to introduction of gaugeon fields also possesses form invariance under quantum gauge transformations. It is observed that the gaugeon field together with gauge field naturally acquire mass, which is different from the conventional Higgs mechanism. The quantum gauge transformation implements a shift in gauge parameter. Further, we analyze the BRST symmetric gaugeon formalism in VSR which embeds only one subsidiary condition rather than two.
Increasing stability and accuracy of the lattice Boltzmann scheme: recursivity and regularization
Malaspinas, Orestis
2015-01-01
In the present paper a lattice Boltzmann scheme is presented which exhibits an increased stability and accuracy with respect to standard single- or multi-relaxation-time (MRT) approaches. The scheme is based on a single-relaxation-time model where a special regularization procedure is applied. This regularization is based on the fact that, for a-thermal flows, there exists a recursive way to express the velocity distribution function at any order (in the Hermite series sense) in terms of the ...
Association du personnel
2012-01-01
Special discount to the members of the Staff Association Aquaparc Discounted prices on admission of whole day. Children from 5 to 15 years: 26.– CHF instead of 35.– CHF; Adults from 16 years: 32.– CHF instead of 43.– CHF.Tickets on sale to the Staff Association Secretariat. BCGE Account management on salary account and annual subscription to credit cards free of charge. Other benefits on mortgage loan and financial planning. Comédie de Genève 20% off on full price tickets (also available for partner): from 24 to 32 CHF a ticket instead of 30 to 40 CHF depending on the shows. Ezee Suisse 15% off on the range of electric bikes upon presentation of your Staff Association membership card before payment. FNAC 5% discount on gifts card available in four Swiss shops without any restriction. Gifts card on sale to the Staff Association Secretariat. FutureKids 15% off for the Staff Association members who enrol their children of 5 to 16 years old in ...
Fern-like rGO/BiVO4 Hybrid Nanostructures for High-Energy Symmetric Supercapacitor.
Patil, Santosh S; Dubal, Deepak P; Deonikar, Virendrakumar G; Tamboli, Mohaseen S; Ambekar, Jalindar D; Gomez-Romero, Pedro; Kolekar, Sanjay S; Kale, Bharat B; Patil, Deepak R
2016-11-23
Herein, we demonstrate the synthesis of rGO/BiVO4 hybrid nanostructures by facile hydrothermal method. Morphological studies reveal that rGO sheets are embedded in the special dendritic fern-like structures of BiVO4. The rGO/BiVO4 hybrid architecture shows the way to a rational design of supercapacitor, since these structures enable easy access of electrolyte ions by reducing internal resistance. Considering the unique morphological features of rGO/BiVO4 hybrid nanostructures, their supercapacitive properties were investigated. The rGO/BiVO4 electrode exhibits a specific capacitance of 151 F/g at the current density of 0.15 mA/cm2. Furthermore, we have constructed rGO/BiVO4 symmetric cell which exhibits outstanding volumetric energy density of 1.6 mW h/cm3 (33.7 W h/kg) and ensures rapid energy delivery with power density of 391 mW/cm3 (8.0 kW/kg). The superior properties of symmetric supercapacitor can be attributed to the special dendritic fern-like BiVO4 morphology and intriguing physicochemical properties of rGO.
Marica, Aurora
2014-01-01
This work describes the propagation properties of the so-called symmetric interior penalty discontinuous Galerkin (SIPG) approximations of the 1-d wave equation. This is done by means of linear approximations on uniform meshes. First, a careful Fourier analysis is constructed, highlighting the coexistence of two Fourier spectral branches or spectral diagrams (physical and spurious) related to the two components of the numerical solution (averages and jumps). Efficient filtering mechanisms are also developed by means of techniques previously proved to be appropriate for classical schemes like finite differences or P1-classical finite elements. In particular, the work presents a proof that the uniform observability property is recovered uniformly by considering initial data with null jumps and averages given by a bi-grid filtering algorithm. Finally, the book explains how these results can be extended to other more sophisticated conforming and non-conforming finite element methods, in particular to quad...
Directory of Open Access Journals (Sweden)
Shin-Yan Chiou
2013-01-01
Full Text Available Mobile authentication can be used to verify a mobile user’s identity. Normally this is accomplished through the use of logon passwords, but this can raise the secret-key agreement problem between entities. This issue can be resolved by using a public-key cryptosystem, but mobile devices have limited computation ability and battery capacity and a PKI is needed. In this paper, we propose an efficient, non-PKI, authenticated, and blind issued symmetric key protocol for mobile access control systems. An easy-to-deploy authentication and authenticated key agreement system is designed such that empowered mobile devices can directly authorize other mobile devices to exchange keys with the server upon authentication using a non-PKI system without trusted parties. Empowered mobile users do not know the key value of the other mobile devices, preventing users from impersonating other individuals. Also, for security considerations, this system can revoke specific keys or keys issued by a specific user. The scheme is secure, efficient, and feasible and can be implemented in existing environments.
Time-reversal symmetric work distributions for closed quantum dynamics in the histories framework
Miller, Harry J. D.; Anders, Janet
2017-06-01
A central topic in the emerging field of quantum thermodynamics is the definition of thermodynamic work in the quantum regime. One widely used solution is to define work for a closed system undergoing non-equilibrium dynamics according to the two-point energy measurement scheme. However, due to the invasive nature of measurement the two-point quantum work probability distribution cannot describe the statistics of energy change from the perspective of the system alone. We here introduce the quantum histories framework as a method to characterise the thermodynamic properties of the unmeasured, closed dynamics. Constructing continuous power operator trajectories allows us to derive an alternative quantum work distribution for closed quantum dynamics that fulfils energy conservation and is time-reversal symmetric. This opens the possibility to compare the measured work with the unmeasured work, contrasting with the classical situation where measurement does not affect the work statistics. We find that the work distribution of the unmeasured dynamics leads to deviations from the classical Jarzynski equality and can have negative values highlighting distinctly non-classical features of quantum work.
Frequency-domain and time-domain solvers of parabolic equation for rotationally symmetric geometries
He, Zi; Chen, Ru-Shan
2017-11-01
Both the frequency-domain and the time-domain body of revolution parabolic equations (FD-BoR-PE, TD-BoR-PE) are derived in this paper. By taking advantage of the rotationally symmetrical property, better performance of the PE method can be achieved for the analysis of bodies of revolution (BoRs). In each transverse plane, only the unknowns of a line, which starts from the center and passes through the node on the generatrix, need to be calculated. Then the unknowns for each transverse plane can be obtained by Fourier series summation for each Fourier mode and the calculation can be taken with a marching manner along the paraxial direction of the PE. As a result, the computational resources can be reduced greatly when compared with the traditional CN, alternating direction implicit (ADI) and alternating group explicit (AGE) finite difference schemes. Both the propagating and scattering problems are given to demonstrate the validity and efficiency of the proposed methods.
Quantum broadcast scheme and multi-output quantum teleportation via four-qubit cluster state
Yu, Yan; Zha, Xin Wei; Li, Wei
2017-02-01
In this paper, two theoretical schemes of the arbitrary single-qubit states via four-qubit cluster state are proposed. One is three-party quantum broadcast scheme, which realizes the broadcast among three participants. The other is multi-output quantum teleportation. Both allow two distant receivers to simultaneously and deterministically obtain the arbitrary single-qubit states, respectively. Compared with former schemes of an arbitrary single-qubit state, the proposed schemes realize quantum multi-cast communication efficiently, which enables Bob and Charlie to obtain the states simultaneously in the case of just knowing Alice's measurement results. The proposed schemes play an important role in quantum information, specially in secret sharing and quantum teleportation.
Directory of Open Access Journals (Sweden)
Y. Lee
2014-12-01
Full Text Available In orthogonal frequency division multiplexing (OFDM systems, an integer part of a frequency offset (IFO that causes ambiguity in data demodulation is estimated generally by comparing correlations between the received and local signals for IFO candidates. In this paper, we propose an IFO estimation scheme that provides a tradeoff between the estimation performance and the computational complexity including a conventional scheme as a special case. In the proposed scheme, template signals are formed by combining frequency-shifted training symbols, allowing the receiver to reduce the number of IFO candidates in the estimation process. Numerical results illustrate the tradeoff of the proposed scheme: The proposed scheme exhibits a tradeoff between the correct estimation probability and the computational complexity taking the number of the training symbols used to construct the template signal as a parameter.
Directory of Open Access Journals (Sweden)
G.G. Zhemerov
2015-08-01
Full Text Available Purpose. Three-phase energy supply system with a symmetrical resistive load operates in mode with the highest possible efficiency in a case of zero instantaneous reactive power and the absence of pulsations instantaneous active power. When load parameters are changed, three-phase energy supply system starts to operate in a mode with additional energy losses. The goal of the paper is to determinate the relations between the components of additional losses and their rezone. Methodology. We have applied the modern theory of instantaneous active and reactive power, the graphical filling complex branched energy supply system of simplified design scheme, the theory of electrical circuits, computer Matlab-simulation. Results. We have developed an universal relation to determine the components of total power loss in the three-phase supply systems with symmetrical three-phase sinusoidal voltage source and any possible load. Further verification of this relation in the Matlab-model of three-phase energy supply system shows its high accuracy. Originality. For the first time, we have carried out relation between RMS reactive and RMS active power instantaneous pulsation and the corresponding components of additional losses. Consequently it becomes possible to offer a unique method of weighting evaluation. Practical value. We have developed position for detecting the causes of additional losses in three-phase supply systems with symmetrical sinusoidal voltage source, as well as to substantiate the correctness of the choice of filter-compensating device. We have developed a Matlab-model which allows to investigate the energy efficiency of three-phase energy supply system and to calculate the components of additional power losses of any possible reasons for their occurrence.
METAPHORIC MECHANISMS IN IMAGE SCHEME DEVELOPMENT
National Research Council Canada - National Science Library
Pankratova, S.A
2017-01-01
.... In the summary the author underscores that both ways of image scheme development are of importance to cognitive science, both heuristic epiphora and image-based diaphora play a significant role in the explication of image scheme development.
Hagen, Wim J H; Wan, William; Briggs, John A G
2017-02-01
Cryo-electron tomography (cryoET) allows 3D structural information to be obtained from cells and other biological samples in their close-to-native state. In combination with subtomogram averaging, detailed structures of repeating features can be resolved. CryoET data is collected as a series of images of the sample from different tilt angles; this is performed by physically rotating the sample in the microscope between each image. The angles at which the images are collected, and the order in which they are collected, together are called the tilt-scheme. Here we describe a "dose-symmetric tilt-scheme" that begins at low tilt and then alternates between increasingly positive and negative tilts. This tilt-scheme maximizes the amount of high-resolution information maintained in the tomogram for subsequent subtomogram averaging, and may also be advantageous for other applications. We describe implementation of the tilt-scheme in combination with further data-collection refinements including setting thresholds on acceptable drift and improving focus accuracy. Requirements for microscope set-up are introduced, and a macro is provided which automates the application of the tilt-scheme within SerialEM. Copyright © 2016 The Authors. Published by Elsevier Inc. All rights reserved.
Energy Technology Data Exchange (ETDEWEB)
Baxevanou, Catherine A.; Vlachos, Nicolas S.
2004-07-01
This paper is a comparative study of combining turbulence models and interpolation schemes to calculate turbulent flow around a NACA0012 airfoil before and after separation. The calculations were carried out using the code CAFFA of Peric, which was appropriately modified to include more numerical schemes and turbulence models. This code solves the Navier-Stokes equations for 2D incompressible flow, using finite volumes and structured, collocated, curvilinear, body fitted grids. Seven differencing schemes were investigated: central, upwind, hybrid, QUICK, Harten-Yee upwind TVD with five limiters, Roe-Sweby upwind TVD with three limiters, and Davis-Yee symmetric TVD with three limiters. Turbulence effects were incorporated using four turbulence models: standard {kappa}-{epsilon}, {kappa}-{omega} high Re with wall functions, {kappa}-{omega} high Re with integration up to the wall, and the {kappa}-{omega} low Re model. A parametric study showed that best results are obtained: a) for the {kappa}-{epsilon} model, when using the Harten-Yee upwind TVD scheme for the velocities and the upwind interpolation for the turbulence properties {kappa} and {epsilon}, and b) for the {kappa}-{omega} models, when using the Harten-Yee upwind TVD scheme with different limiters for the velocities and the turbulence quantities {kappa} and {omega}. The turbulence models that integrate up to the wall are more accurate when separation appears, while those using wall functions converge much faster. (Author)
Energy Technology Data Exchange (ETDEWEB)
Baxevanou, C.A.; Vlachos, N.S.
2004-07-01
This paper is a comparative study of combining turbulence models and interpolation schemes to calculate turbulent flow around a NACA0012 airfoil before and after separation. The calculations were carried out using the code CAFFA of Peric, which was appropriately modified to include more numerical schemes and turbulence models. This code solves the Navier-Stokes equations for 2D incompressible flow, using finite volumes and structured, collocated, curvilinear, body fitted grids. Seven differencing schemes were investigated: central, upwind, hybrid, QUICK, Harten-Yee upwind TVD with five limiters, Roe-Sweby upwind TVD with three limiters, and Davis-Yee symmetric TVD with three limiters. Turbulence effects were incorporated using four turbulence models: standard k-{epsilon}, k-{omega} high Re with wall functions, k-{omega} high Re with integration up to the wall, and the k-{omega} low Re model. A parametric study showed that best results are obtained: a) for the k-{epsilon} model, when using the Harten-Yee upwind TVD scheme for the velocities and the upwind interpolation for the turbulence properties k and {epsilon}, and b) for the k-{omega}, models, when using the Harten-Yee upwind TVD scheme with different limiters for the velocities and the turbulence quantities k and {omega}. The turbulence models that integrate up to the wall are more accurate when separation appears, while those using wall functions converge much faster. (author)
The Terwilliger algebra of an almost-bipartite P- and Q-polynomial association scheme
Caughman, John S.; MacLean, Mark S.; Terwilliger, Paul M.
2005-01-01
Let $Y$ denote a $D$-class symmetric association scheme with $D \\geq 3$, and suppose $Y$ is almost-bipartite P- and Q-polynomial. Let $x$ denote a vertex of $Y$ and let $T=T(x)$ denote the corresponding Terwilliger algebra. We prove that any irreducible $T$-module $W$ is both thin and dual thin in the sense of Terwilliger. We produce two bases for $W$ and describe the action of $T$ on these bases. We prove that the isomorphism class of $W$ as a $T$-module is determined by two parameters, the ...
Key management schemes using routing information frames in secure wireless sensor networks
Kamaev, V. A.; Finogeev, A. G.; Finogeev, A. A.; Parygin, D. S.
2017-01-01
The article considers the problems and objectives of key management for data encryption in wireless sensor networks (WSN) of SCADA systems. The structure of the key information in the ZigBee network and methods of keys obtaining are discussed. The use of a hybrid key management schemes is most suitable for WSN. The session symmetric key is used to encrypt the sensor data, asymmetric keys are used to encrypt the session key transmitted from the routing information. Three algorithms of hybrid key management using routing information frames determined by routing methods and the WSN topology are presented.
The Ubiquity of Smooth Hilbert Schemes
Staal, Andrew P.
2017-01-01
We investigate the geography of Hilbert schemes that parametrize closed subschemes of projective space with a specified Hilbert polynomial. We classify Hilbert schemes with unique Borel-fixed points via combinatorial expressions for their Hilbert polynomials. We realize the set of all nonempty Hilbert schemes as a probability space and prove that Hilbert schemes are irreducible and nonsingular with probability greater than $0.5$.
MIRD radionuclide data and decay schemes
Eckerman, Keith F
2007-01-01
For all physicians, scientists, and physicists working in the nuclear medicine field, the MIRD: Radionuclide Data and Decay Schemes updated edition is an essential sourcebook for radiation dosimetry and understanding the properties of radionuclides. Includes CD Table of Contents Decay schemes listed by atomic number Radioactive decay processes Serial decay schemes Decay schemes and decay tables This essential reference for nuclear medicine physicians, scientists and physicists also includes a CD with tabulations of the radionuclide data necessary for dosimetry calculations.
THROUGHPUT ANALYSIS OF EXTENDED ARQ SCHEMES
African Journals Online (AJOL)
PUBLICATIONS1
and Wait (SW), Selective Repeat (SR), Stutter. (ST) and Go-Back-N (GBN) (Lin and Costello,. 2003). Combinations of these schemes lead to mixed mode schemes which include the SR-. GBN, SR-ST1 and SR-ST2. In the mixed mode schemes, when a prescribed number of failures occur in the SR mode, the GBN or ST ...
The Original Management Incentive Schemes
Richard T. Holden
2005-01-01
During the 1990s, the structure of pay for top corporate executives shifted markedly as the use of stock options greatly expanded. By the early 2000s, as the dot-com boom ended and the Nasdaq stock index melted down, these modern executive incentive schemes were being sharply questioned on many grounds—for encouraging excessive risk-taking and a short-run orientation, for being an overly costly and inefficient method of providing incentives, and even for tempting managers of firms like Enron,...
The mathematics of Ponzi schemes
Artzrouni, Marc
2009-01-01
A first order linear differential equation is used to describe the dynamics of an investment fund that promises more than it can deliver, also known as a Ponzi scheme. The model is based on a promised, unrealistic interest rate; on the actual, realized nominal interest rate; on the rate at which new deposits are accumulated and on the withdrawal rate. Conditions on these parameters are given for the fund to be solvent or to collapse. The model is fitted to data available on Charles...
Hydrological Validation of The Teb Scheme On A Suburban Basin
Lemonsu, A.; Masson, V.; Noilhan, J.
The aim of this work is to validate the hydrological part of the TEB (Town Energy Balance) scheme (Masson, 2000), using the measurements recorded in the Reze basin (Nantes, France). The Reze basin is a residential area of 4.7 Ha, which is made of individual houses and gardens. On this site, hydrological parameters have been con- tinuously collected from 1991 to 1998, specially the flows from the sanitary sewer. A 6-year simulation with TEB off-line is done on a single grid point and the simulated runoff is compared with the observations. The modelisation of the water exchanges is quite simple in the TEB scheme and sup- poses that the urban materials are perfectly impervious. This work shows that the re- laxation of this hypothesis is necessary for roads: allowing for an infiltration process over roads critically improves the Nash criteria. This new infiltration parameterization in the model is coherent with micro-measurements made for such pavement.
Baryon symmetric big-bang cosmology. [matter-antimatter symmetry
Stecker, F. W.
1978-01-01
The framework of baryon-symmetric big-bang cosmology offers the greatest potential for deducing the evolution of the universe as a consequence of physical laws and processes with the minimum number of arbitrary assumptions as to initial conditions in the big-bang. In addition, it offers the possibility of explaining the photon-baryon ratio in the universe and how galaxies and galaxy clusters are formed, and also provides the only acceptable explanation at present for the origin of the cosmic gamma ray background radiation.
Control of Power in Parity-Time -Symmetric Lattices
Kozlov, Maksim
2015-01-01
We investigate wave transport properties of Parity-Time (PT) symmetric lattices that are periodically modulated along the direction of propagation. We demonstrate that in the regime of unbroken PT-symmetry the system Floquet-Bloch modes may interfere constructively leading to either controlled oscillations or linear power absorption and amplification occurring exactly at the phase transition point. The differential power response is effected by the overlap of the gain and loss system distribution with wave intensity pattern that is formed through Rabi oscillations engaging the coupled Floquet-Bloch modes.
The Topology of Three-Dimensional Symmetric Tensor Fields
Lavin, Yingmei; Levy, Yuval; Hesselink, Lambertus
1994-01-01
We study the topology of 3-D symmetric tensor fields. The goal is to represent their complex structure by a simple set of carefully chosen points and lines analogous to vector field topology. The basic constituents of tensor topology are the degenerate points, or points where eigenvalues are equal to each other. First, we introduce a new method for locating 3-D degenerate points. We then extract the topological skeletons of the eigenvector fields and use them for a compact, comprehensive description of the tensor field. Finally, we demonstrate the use of tensor field topology for the interpretation of the two-force Boussinesq problem.
A Symmetrical Interpretation of the Klein-Gordon Equation
Heaney, Michael B.
2013-06-01
This paper presents a new Symmetrical Interpretation (SI) of relativistic quantum mechanics which postulates: quantum mechanics is a theory about complete experiments, not particles; a complete experiment is maximally described by a complex transition amplitude density; and this transition amplitude density never collapses. This SI is compared to the Copenhagen Interpretation (CI) for the analysis of Einstein's bubble experiment. This SI makes several experimentally testable predictions that differ from the CI, solves one part of the measurement problem, resolves some inconsistencies of the CI, and gives intuitive explanations of some previously mysterious quantum effects.
Hardware Realization of Chaos Based Symmetric Image Encryption
Barakat, Mohamed L.
2012-06-01
This thesis presents a novel work on hardware realization of symmetric image encryption utilizing chaos based continuous systems as pseudo random number generators. Digital implementation of chaotic systems results in serious degradations in the dynamics of the system. Such defects are illuminated through a new technique of generalized post proceeding with very low hardware cost. The thesis further discusses two encryption algorithms designed and implemented as a block cipher and a stream cipher. The security of both systems is thoroughly analyzed and the performance is compared with other reported systems showing a superior results. Both systems are realized on Xilinx Vetrix-4 FPGA with a hardware and throughput performance surpassing known encryption systems.
Unidirectional Invisibility induced by PT-Symmetric Periodic Structures
Lin, Zin; Eichelkraut, Toni; Kottos, Tsampikos; Cao, Hui; Christodoulides, Demetrios N; 10.1103/PhysRevLett.106.213901
2011-01-01
We show that parity-time (PT) symmetric Bragg periodic structures, near the spontaneous PT - symmetry breaking point, can act as unidirectional invisible media. In this regime, the re flection from one end is diminished while it is enhanced from the other. At the same time the transmission coefficient and phase, are indistinguishable from those expected in the absence of a grating. The phenomenon is robust even in the presence of Kerr non-linearities, and it can also eff?ectively suppress optical bistabilities.
Control of power in parity-time symmetric lattices
Kozlov, Maksim; Tsironis, G. P.
2015-10-01
We investigate wave transport properties of parity-time (PT) symmetric lattices that are periodically modulated along the direction of propagation. We demonstrate that in the regime of unbroken PT-symmetry, the system Floquet-Bloch modes may interfere constructively leading to either controlled oscillations or power absorption and unlimited amplification occurring exactly at the phase-transition point. The differential power response is affected by the overlap of the gain and loss system distribution with wave intensity pattern that is formed through Rabi oscillations engaging the coupled Floquet-Bloch modes.
DSM complete synthetic seismograms: SH, spherically symmetric, case
Cummins, Phil R.; Geller, Robert J.; Hatori, Tomohiko; Takeuchi, Nozomu
1994-04-01
We present a new technique, based om the Direct Solution Method (DSM) (Geller et al., 1990; Hara et al., 1991; Geller and Ohminato, 1994), for calculating SH (toroidal) synthetic seismograms for spherically symmetric, isotropic, media. No asymptotic approximations are used and the synthetics, which fully include both body and surface waves, can be computed for a broad range of frequencies. Our algorithm accurately handles sources that require discontinuities in the vertically dependent part of the displacement. We use matrix operators that minimize the numerical error of the solutions. An example synthetic profile is presented for a 600km deep source in the IASP91 model for the period range 4-5000s.
Gravitation-Wave Emission in Shift-Symmetric Horndeski Theories.
Barausse, Enrico; Yagi, Kent
2015-11-20
Gravity theories beyond general relativity typically predict dipolar gravitational emission by compact-star binaries. This emission is sourced by "sensitivity" parameters depending on the stellar compactness. We introduce a general formalism to calculate these parameters, and show that in shift-symmetric Horndeski theories stellar sensitivities and dipolar radiation vanish, provided that the binary's dynamics is perturbative (i.e., the post-Newtonian formalism is applicable) and cosmological-expansion effects can be neglected. This allows one to reproduce the binary-pulsar-observed orbital decay.