bluuebunny/crossref_metadata_2025 huggingface dataset:
In Vivo Phosphorylation of Partner Switching Regulators Correlates with Stress Transmission in the Environmental Signaling Pathway ofBacillus subtilis
Authors: Kim Tae-Jong , Gaidenko Tatiana A. , Price Chester W.
Published: September 2004

Exposure of bacteria to diverse growth-limiting stresses induces the synthesis of a common set of proteins which provide broad protection against future, potentially lethal stresses. AmongBacillus subtilisand its relatives, this general stress response is controlled by the σBtranscription factor. Signals of environmental and energy stress activate σBthrough a multicomponent network that functions via a partner switching mechanism, in which protein-protein interactions are governed by serine and threonine phosphorylation. Here, we tested a central prediction of the current model for the environmental signaling branch of this network. We used isoelectric focusing and immunoblotting experiments to determine the in vivo phosphorylation states of the RsbRA and RsbS regulators, which act in concert to negatively control the RsbU environmental signaling phosphatase. As predicted by the model, the ratio of the phosphorylated to unphosphorylated forms of both RsbRA and RsbS increased in response to salt or ethanol stress. However, these two regulators differed substantially with regard to the extent of their phosphorylation under both steady-state and stress conditions, with RsbRA always the more highly modified. Mutant analysis showed that the RsbT kinase, which is required for environmental signaling, was also required for the in vivo phosphorylation of RsbRA and RsbS. Moreover, the T171A alteration of RsbRA, which blocks environmental signaling, also blocked in vivo phosphorylation of RsbRA and impeded phosphorylation of RsbS. These in vivo results corroborate previous genetic analyses and link the phosphorylated forms of RsbRA and RsbS to the active transmission of environmental stress signals.
Processing of the Tail Lysozyme (gp5) of Bacteriophage T4
Authors: Ye Nanzhang , Nemoto Naoki
Published: September 2004

The processing site of gp5 has been determined to be between residues Val-390 and His-391, instead of Ser-351 and Ala-352 as previously reported (H. Kanamaru, N. C. Gassner, N. Ye, S. Takeda, and F. Arisaka, J. Bacteriol. 181:2739-2744). Moreover, the maturation of gp5 is abolished by null mutations in other hub genes, indicating that cleavage requires the interactions of several baseplate proteins.
EFFICIENT DYNAMIC LOOKUP FOR BURSTY ACCESS PATTERNS
Authors: SAHNI SARTAJ , KIM KUN SUK
Published: August 2004

Internet (IP) packet forwarding is typically done by finding the longest prefix in a router table that matches the packet's destination address. Although significant effort has been devoted to the development of data structures for static and dynamic router-tables for random packet-access-patterns, considerably less effort has been expended in the development of such structures for bursty access-patterns (i.e., streams of packets in which destination addresses repeat frequently within localized windows of packets). In this paper, we first formulate a variant, ACRBT (alternative collection of red-black trees), of the CRBT (collection of red-black trees) data structure proposed earlier for dynamic router-tables. By replacing the red-black trees used in the ACRBT with splay trees, we obtain the CST (collection of splay trees) structure in which search, insert, and delete take O( log n) amortized time per operation, where n is the number of prefixes in the router table. By replacing the front end of the CST with biased skip lists, we obtain the BSLPT (biased skip lists with prefix trees) structure in which search, insert, and delete take O( log n) expected time. The CST and BSLPT structures are designed so as to perform much better when the access pattern is bursty than when it is not. Experimental results using real IPv4 routing databases and synthetically generated search sequences as well as trace sequences are presented. For extremely bursty access patterns, the CST structure is best. Otherwise, the ACRBT is recommended. Our experiments also indicate that a supernode implementation of the ACRBT usually has better search performance than does the traditional one-element-per-node implementation.
ON MINIMIZING TOTAL COMPLETION TIME IN BATCH MACHINE SCHEDULING
Authors: POON CHUNG KEUNG , YU WENCI
Published: August 2004

We study the scheduling problem on a batch machine which is capable of processing a batch of jobs at a time. For a batch machine of capacity c, we designed an algorithm for minimizing the total completion time in O(n6c) time (for sufficiently large c). This improves the best previous time bound of O(nc(c-1)) given by Brucker et al [1]. We also designed a new algorithm with running time [Formula: see text].
QUANTUM AUTHENTICATION USING ENTANGLED STATES
Authors: LI XIAOYU , BARNUM HOWARD
Published: August 2004

A quantum authentication scheme is presented in this paper. Two parties share Einstein-Podolsky-Rosen(EPR) pairs previously as the identification token. They create auxiliary EPR pairs to interact with the identification token. Then the authentication is accomplished by a complete Bell state measurement. This scheme is proved to be secure. If no errors and eavesdroppers exist in the transmission, the identification token is unchanged after the authentication. So it can be reused.
A CLASS OF GRAPHS WHICH HAS EFFICIENT RANKING AND UNRANKING ALGORITHMS FOR SPANNING TREES AND FORESTS
Authors: EĞECIOĞLU ÖMER , REMMEL JEFFREY B. , WILLIAMSON S. GILL
Published: August 2004

Remmel and Williamson recently defined a class of directed graphs, called filtered digraphs, and described a natural class of bijections between oriented spanning forests of these digraphs and associated classes of functions [12]. Filtered digraphs include many specialized graphs such as complete k-partite graphs. The Remmel-Williamson bijections provide explicit formulas for various multivariate generating functions for the oriented spanning forests which arise in this context. In this paper, we prove another important property of these bijections, namely, that it allows one to construct efficient algorithms for ranking and unranking spanning trees or spanning forests of filtered digraphs G. For example, we show that if G=(V,E) is a filtered digraph and SP(G) is the collection of spanning trees of G, then our algorithm requires O(|V|) operations of sum, difference, product, quotient, and comparison of numbers less than or equal |SP(G)| to rank or unrank spanning trees of G.
ANALYSIS OF WEB SEARCH ALGORITHM HITS
Authors: HONG DAWEI , MAN SHUSHUANG
Published: August 2004

One of the well known Web search algorithms is HITS by Kleinberg [9]. We analyze the stability of HITS, when and how much outputs of HITS depend on initial values chosen by the algorithm. More importantly, we proposed a model for a type of hyperlink structures, which have been frequently observed on the Web, and we prove that in the model a crucial technical assumption made in HITS is satisfied, and accordingly HITS works well.
ON THE DESCRIPTIONAL COMPLEXITY OF LINDENMAYER SYSTEMS
Authors: DASSOW JÜRGEN
Published: August 2004

We define the number of productions and the number of symbols as measures of descriptional complexity for tabled interactionless Lindenmayer systems and their special cases. We investigate the decrease of the descriptional complexities if we go from a family to another one which has a larger generative capacity.
FAST ALGORITHMS FOR 3-D DOMINANCE REPORTING AND COUNTING
Authors: SHI QINGMIN , JAJA JOSEPH
Published: August 2004

We present in this paper fast algorithms for the 3-D dominance reporting and counting problems, and generalize the results to the d-dimensional case. Our 3-D dominance reporting algorithm achieves O( log n/ log log n+f) query time using O(n log ∊ n) space, where f is the number of points satisfying the query and ∊>0 is an arbitrarily small constant. For the 3-D dominance counting problem (which is equivalent to the 3-D range counting problem), our algorithm runs in O(( log n/ log log n)2) time using O(n log1+∊n/ log log n) space.
BAND EDGE EIGENFUNCTIONS AND EIGENVALUES FOR PERIODIC POTENTIALS THROUGH THE QUANTUM HAMILTON–JACOBI FORMALISM
Authors: SREE RANJANI S. , KAPOOR A. K. , PANIGRAHI P. K.
Published: August 2004

We demonstrate the procedure of finding the band edge eigenfunctions and eigenvalues of periodic potentials, through the quantum Hamilton–Jacobi formalism. The potentials studied here are the Lamé and associated Lamé, which belong to the class of elliptic potentials. The formalism requires an assumption about the singularity structure of the quantum momentum function p, obeying a Riccati type equation in the complex x-plane. Essential use is made of suitable conformal transformations, which lead to the eigenvalues and the eigenfunctions corresponding to the band edges, in a straightforward manner. Our study reveals interesting features about the singularity structure of p, underlying the band edge states.
BASIC SYMPLECTIC GEOMETRY FOR p-BRANES WITH THICKNESS IN A CURVED BACKGROUND
Authors: ESCALANTE ALBERTO
Published: August 2004

We show that the Witten covariant phase space for p-branes with thickness in an arbitrary background is endowed of a symplectic potential, which although is not important to the dynamics of the system, plays a relevant role on the phase space, allowing us to generate a symplectic structure for the theory and therefore give a covariant description of canonical formalism for quantization.
FAR-ULTRAVIOLET SURVEYS OF GLOBULAR CLUSTERS: HUNTING FOR THE PRODUCTS OF STELLAR COLLISIONS AND NEAR MISSES
Authors: KNIGGE CHRISTIAN
Published: August 2004

Globular clusters are gravitationally bound stellar systems containing on the order of 105 stars. Due to the high stellar densities in the cores of these clusters, close encounters and even physical collisions between stars are inevitable. These dynamical interactions can produce exotic types of single and binary stars that are extremely rare in the galactic field, but which may be important to the dynamical evolution of their host clusters. A common feature of these dynamically-formed stellar populations is that many of their members are relatively hot, and thus bright in the far-ultraviolet (FUV) waveband. In this short review, we describe how space-based FUV observations are being used to find and study these populations.
PURE STATES, MIXED STATES AND HAWKING PROBLEM IN GENERALIZED QUANTUM MECHANICS
Authors: SHALYT-MARGOLIN A. E.
Published: August 2004

This paper is the continuation of a study into the information paradox problem started by the author in his earlier works. As before, the key instrument is a deformed density matrix in quantum mechanics of the early universe. It is assumed that the latter represents quantum mechanics with fundamental length. It is demonstrated that the obtained results agree well with the canonical viewpoint that in the processes involving black holes pure states go to the mixed ones in the assumption that all measurements are performed by the observer in a well-known quantum mechanics. Also it is shown that high entropy for Planck's remnants of black holes appearing in the assumption of the generalized uncertainty relations may be explained within the scope of the density matrix entropy introduced by the author previously. It is noted that the suggested paradigm is consistent with the holographic principle. Because of this, a conjecture is made about the possibility for obtaining the generalized uncertainty relations from the covariant entropy bound at high energies in the same way as Bousso has derived Heisenberg's uncertainty principle for the flat space.
D-BRANE INTERACTIONS IN A GRAVITATIONAL SHOCK WAVE BACKGROUND
Authors: GIRARDELLO L. , PICCIONI C. , PORRATI M.
Published: August 2004

We study D-branes in the background of a gravitational shock wave. We consider the case of parallel D-branes located on opposite sides with respect to the shock wave. Their interaction is studied by evaluating the cylinder diagram using the boundary states technique. Boundary states are defined at each D-brane and their scalar product is evaluated after propagation through the shock wave. Taking the limit where the gravitational shock wave vanishes, we show that the amplitude evaluated is consistent with the flat spacetime result.
A NOTE ON TACHYONS IN THE $D3+\overline{D3}$ SYSTEM
Authors: MIAO YAN-GANG , MÜLLER-KIRSTEN HARALD J. W. , PARK DAE KIL
Published: August 2004

The periodic bounce of Born–Infeld theory of D3-branes is derived, and the BPS limit of infinite period is discussed as an example of tachyon condensation. The explicit bounce solution to the Born–Infeld action is interpreted as an unstable fundamental string stretched between the brane and its antibrane.
CORNWALL–JACKIW–TOMBOULIS EFFECTIVE POTENTIAL FOR CANONICAL NONCOMMUTATIVE FIELD THEORIES
Authors: MANDANICI GIANLUCA
Published: September 2004

We apply the Cornwall–Jackiw–Tomboulis (CJT) formalism to the scalar λφ4 theory in canonical-noncommutative space–time. We construct the CJT effective potential and the gap equation for general values of the noncommutative parameter θμν. We observe that under the hypothesis of translational invariance, which is assumed in the effective potential construction, differently from the commutative case (θμν=0), the renormalizability of the gap equation is incompatible with the renormalizability of the effective potential. We argue that our result, is consistent with previous studies, suggesting that a uniform ordered phase would be inconsistent with the infrared structure of canonical noncommutative theories.
PHASE SHIFTS AND RESONANCES IN THE DIRAC EQUATION
Authors: KENNEDY PIERS , DOMBEY NORMAN , HALL RICHARD L.
Published: September 2004

We review the analytic results for the phase shifts δl(k) in nonrelativistic scattering from a spherical well. The conditions for the existence of resonances are established in terms of time-delays. Resonances are shown to exist for p-waves (and higher angular momenta) but not for s-waves. These resonances occur when the potential is not quite strong enough to support a bound p-wave of zero energy. We then examine relativistic scattering by spherical wells and barriers in the Dirac equation. In contrast to the nonrelativistic situation, s-waves are now seen to possess resonances in scattering from both wells and barriers. When s-wave resonances occur for scattering from a well, the potential is not quite strong enough to support a zero momentum s-wave solution at E=m. Resonances resulting from scattering from a barrier can be explained in terms of the "crossing" theorem linking s-wave scattering from barriers to p-wave scattering from wells. A numerical procedure to extract phase shifts for general short range potentials is introduced and illustrated by considering relativistic scattering from a Gaussian potential well and barrier.
CARTESIAN PRODUCT OF SIMPLICIAL AND CELLULAR STRUCTURES
Authors: LIENHARDT PASCAL , SKAPIN XAVIER , BERGEY ANTOINE
Published: August 2004

Classical topology-based operations such as extrusion (or more generally Minkowski sums) are defined by a cartesian product of combinatorial structures describing the topology of geometric space subdivisions. In this paper, we define the cartesian product operation for four different structures: semi-simplicial sets, generalized maps, oriented maps and chains of maps. We follow a homogeneous framework allowing to define the cartesian product for any simplicial and cellular structures derived from simplicial sets and combinatorial maps. This results from the relationships already established between these structures and those used in computational geometry and geometric modeling. For esch structure we have studied, we additionally provide a time-optimal computation algorithm.
USING INVARIANTS TO EXTRACT GEOMETRIC CHARACTERISTICS OF CONIC SECTIONS FROM RATIONAL QUADRATIC PARAMETERIZATIONS
Authors: GOLDMAN RON , WANG WENPING
Published: August 2004

Extracting the geometric characteristics of conic sections, such as their center, axes and foci, from their defining equations is required for various applications in computer graphics and geometric modeling. Although there exist standard techniques for computing the geometric characteristics for conics in implicit form, in shape modeling applications conic sections are often represented by rational quadratic parameterizations. Here we present closed formulas for computing the geometric characteristics of conics directly from their quadratic parameterizations without resorting to implicitization procedures. Our approach uses the invariants of rational quadratic parameterizations under rational linear reparameterizations. These invariants are also used to give a complete characterization of degenerate tonics represented by rational quadratic parameterizations.
APPROXIMATING 3D POINTS WITH CYLINDRICAL SEGMENTS
Authors: ZHU BINHAI
Published: August 2004

In this paper, we study a 3D geometric problem originated from computing neural maps in the computational biology community: Given a set S of n points in 3D, compute k cylindrical segments (with different radii, orientations, lengths and no segment penetrates another) enclosing S such that the sum of their radii is minimized. There is no known result in this direction except when k=1. The general problem is strongly NP-hard and we obtain a polynomial time approximation scheme (PTAS) for any fixed k>1 in O(n3k-2/δ4k-3) time by returning k cylindrical segments with sum of radii at most (1+δ) of the corresponding optimal value, if exist. Our PTAS is built upon a simple (though slower) approximation algorithm for the case when k=1.
PATHWIDTH AND LAYERED DRAWINGS OF TREES
Authors: SUDERMAN MATTHEW
Published: August 2004

An h-layer drawing of a graph G is a planar drawing of G in which each vertex is placed on one of h parallel lines and each edge is drawn as a straight line between its end-vertices. In such a drawing, we say that an edge is proper if its endpoints lie on adjacent layers, flat if they lie on the same layer and long otherwise. Thus, a proper h-layer drawing contains only proper edges, a short h-layer drawing contains no long edges, an upright h-layer drawing contains no flat edges, and an unconstrained h-layer drawing contains any type of edge. In this paper, we derive upper and lower bounds on the number of layers required by proper, short, upright, and unconstrained layered drawings of trees. We prove that these bounds are optimal with respect to the pathwidth of the tree being drawn. Finally, we give linear-time algorithms for obtaining layered drawings that match these upper bounds.
COMPUTATIONAL GEOMETRY COLUMN 45
Authors: O'ROURKE JOSEPH
Published: August 2004

The algorithm of Edelsbrunner for surface reconstruction by "wrapping" a set of points in ℝ3is described.
ENTERPRISE ARCHITECTURE: ENABLING INTEGRATION, AGILITY AND CHANGE
Authors: HOOGERVORST JAN
Published: August 2004

Three core imperatives are essential for modern businesses and organizations: seamless integration of customer and operational processes, agility, and the ability to change. These imperatives are relevant in view of successfully executing strategic choices, but all too often not satisfied.

Businesses and organizations are complex adaptive socio-technical systems and can be viewed from two fundamentally different perspectives: the functional (black-box) perspective and the constructional (white-box) perspective. Management and governance of businesses and organizations regard the functional, black-box perspective, which is inherently ill-suited for addressing the imperatives mentioned. It will be argued that establishing system integration, agility and change requires a focus on the system's design, hence necessitates the constructional perspective.

The concept of architecture is considered fundamental for operationalizing the constructional perspective. Next to the more familiar notion of technology architecture, the concepts of business, organizational and information architecture are formally introduced and elucidated. Various domains within these architectures will be highlighted, whereby the importance of coherence and consistency is stressed, especially in view of the ability to change. Collectively, the four architectures are labeled Enterprise Architecture. Finally, enterprise architecture will be positioned as a crucial means for linking strategy development and execution.
PROJECT GRAAL: TOWARDS OPERATIONAL ARCHITECTURE ALIGNMENT
Authors: VAN ECK PASCAL , BLANKEN HENK , WIERINGA ROEL
Published: August 2004

This paper presents a framework for architecture alignment that can be positioned between approaches for software architecture, which concern software artefacts only, and strategic alignment models, which have a business focus. The framework is currently applied in case study research to find alignment patterns used in practice. First results presented in this paper indicate that the framework might yield an operationalization of strategic architecture alignment models. We also present an alignment pattern which shows a difference between how architectures are designed at the application level and the infrastructure level. We think this difference is significant for practical alignment models.
BRIDGING THE GAP BETWEEN BUSINESS MODELS AND WORKFLOW SPECIFICATIONS
Authors: DEHNERT JULIANE , VAN DER AALST WIL M. P.
Published: August 2004

This paper presents a methodology to bridge the gap between business process modeling and workflow specification. While the first is concerned with intuitive descriptions that are mainly used for communication, the second is concerned with configuring a process-aware information system, thus requiring a more rigorous language less suitable for communication. Unlike existing approaches the gap is not bridged by providing formal semantics for an informal language. Instead it is assumed that the desired behavior is just a subset of the full behavior obtained using a liberal interpretation of the informal business process modeling language. Using a new correctness criterion (relaxed soundness), it is verified whether a selection of suitable behavior is possible. The methodology consists of five steps and is illustrated using event-driven process chains as a business process modeling language and Petri nets as the workflow specification language.
CONCEPTS FOR MODELING ENTERPRISE ARCHITECTURES
Authors: JONKERS HENK , LANKHORST MARC , VAN BUUREN RENÉ , HOPPENBROUWERS STIJN , BONSANGUE MARCELLO , VAN DER TORRE LEENDERT
Published: August 2004

A coherent description of enterprise architecture provides insight, enables communication among stakeholders and guides complicated change processes. Unfortunately, so far no enterprise architecture description language exists that fully enables integrated enterprise modeling, because for each architectural domain, architects use their own modeling techniques and concepts, tool support, visualization techniques, etc. In this paper, we outline such an integrated language and we identify and study concepts that relate architectural domains. In our language, concepts for describing the relationships between architecture descriptions at the business, application, and technology levels play a central role, related to the ubiquitous problem of business-ICT alignment, whereas for each architectural domain we conform to existing languages or standards such as UML. In particular, usage of services offered by one layer to another plays an important role in relating the behaviour aspects of the layers. The structural aspects of the layers are linked through the interface concept, and the information aspects through realization relations.
A DISTRIBUTED, NEAR-OPTIMAL CALL SET-UP PROTOCOL FOR ALL-OPTICAL WAVELENGTH ROUTING NETWORKS
Authors: FREY MICHAEL , HUTTON JAMES
Published: September 2004

A simple distributed "no look-ahead" connection rule with little set-up delay and little control overhead is proposed for interconnection networks representative of all-optical wavelength-routing networks. This connection rule, or call set-up protocol, is designed for networks with installed wavelength changers and supports both dynamic fixed route and dynamic alternative route call set-up. The proposed protocol has near-optimal call set-up probability under the conditions of an elementary route resource model. The protocol also admits explicit analytical expressions for key protocol performance measures, such as call set-up probability and average number of changers used to set up a call.
BUCKLING AND POSTBUCKLING ANALYSIS OF LAMINATED CYLINDRICAL SHELLS USING THE THIRD-ORDER SHEAR DEFORMATION THEORY
Authors: ARCINIEGA R. A. , GONÇALVES P. B. , REDDY J. N.
Published: August 2004

In the present work the buckling and postbuckling behavior of laminated cylindrical shells under axial compression and lateral pressure loading are investigated. A nonlinear theory for thin cylinders incorporating the effects of transverse shear deformation is employed. A modal solution based on the Koiter theory is utilized to derive the nonlinear equilibrium equations for the postcritical behavior of the shell. The Rayleigh–Ritz method is used to obtain analytical solutions for the critical load through algebraic routines written in Maple. Prebuckling and postbuckling equations are also solved by using symbolic computation. The influence played by geometrical parameters of the cylinder and physical parameters of the laminate (i.e. fiber orientation of each lamina, material properties and number of layers) on the critical and postcritical behavior of the shell is examined. It is noticed that the stability of shells is highly dependent on laminate characteristics and, from these observations, it is concluded that specific configurations of laminates should be designed for each kind of application.
THERMAL BUCKLING OF CLAMPED CYLINDRICAL PANELS BASED ON FIRST-ORDER SHEAR DEFORMATION THEORY
Authors: AL-KHALEEFI ABDULLATEEF M.
Published: August 2004

Based on the first-order shear deformation shell theory, an analytical approach is developed to predict the thermal buckling response of an all-edge clamped cylindrical panel. The analytical approach adopts a double Fourier solution method suitable for cylindrical panels. The present solutions are compared with the finite element solutions obtained using ANSYS. The effects of various dimensional parameters are included in the study.
SEISMIC ASSESSMENT OF A RETROFITTED CHIMNEY BY FEM ANALYSIS AND FIELD TESTING
Authors: CHEN CHERN-HWA
Published: August 2004

The Chi-Chi Earthquake that struck Taiwan in 1999 damaged a 250 m tall chimney located in central Taiwan. To understand the dynamic behavior, failure trigger mechanism, and seismic performance of the chimney that has been rehabilitated, a study using experimental and analytical approaches was carried out. The ambient vibration test, together with a system identification approach, was used to evaluate the dynamic characteristics of the chimney. A subspace approach with an instrumental variable concept was used in the system identification. The dynamic behavior of the chimney was also simulated by a 3D finite element analysis using the commercial software SAP2000. Finally, the design code of ASCE 1975 was adopted to check the buckling capacity of the steel flues in the chimney structure. The results indicated that the calculated stresses correspond well with the actual damages observed in the steel flues.
EARTHQUAKE FLOOR SPECTRA FOR UNRESTRAINED BUILDING COMPONENTS
Authors: AL ABADI HAIDER A. , LAM NELSON T. K. , GAD EMAD F. , CHANDLER ADRIAN M.
Published: August 2004

This paper introduces the use of elastic displacement floor spectra to model the seismic performance behavior of unrestrained components. The displacement spectrum has the attribute of tracking period-shifts associated with "rocking" behavior. Analyses of the displacement floor spectra in high-rise buildings demonstrate the significance of contributions by the higher modes of vibration. Significantly, such higher mode contributions could not always be captured by established code procedures wherein the seismic demand on a building floor is obtained by linear interpolation between the seismic demand at the roof and ground level. The significant influence of the higher modes in high-rise buildings also precludes the use of simple static models to predict seismic demand. Results are also presented herein to demonstrate the sensitivity of the displacement floor spectrum to a multitude of modeling uncertainties.
DYNAMIC RESPONSE EVALUATION OF A FRAMED TYPE TURBO-GENERATOR FOUNDATION INCORPORATING DYNAMIC MODULUS AND OPERATING SPEED VARIATIONS
Authors: LAKSHMANAN N. , MUTHUMANI K. , GOPALAKRISHNAN N. , SATHISH KUMAR K.
Published: August 2004

Framed type foundation structures supporting turbo-generator machinery in a power plant have stringent vibration limits to ensure proper functioning of turbine generators without any breakdown. Current dynamic analysis methodology for such dynamically sensitive structures involves modal synthesis considering a single value of operating speed for the machinery and a uniform dynamic modulus for the frame material, which cannot be realized in site conditions. Such variations in the dynamic modulus across the whole structure and running speed of the machinery during normal operation have a profound impact on its dynamic performance which may result in alarmingly increasing amplitudes leading to subsequent breakdown of the machinery. A new methodology is outlined that combines the effects of the two variations by way of considering an enhanced range of speeds on either side of the operating speed for the modal synthesis process. This study shows the effects of variations in the dynamic modulus and operating speed on the peak dynamic response of a typical framed turbo-generator foundation structure. The modal synthesis process adopted in the study includes the significant modes in the sub-resonant range and a band of modes around the operating speed to obtain the peak response of the framed structure.
STRESS CONCENTRATION FACTORS AND FATIGUE FAILURE OF WELDED T-CONNECTIONS IN CIRCULAR HOLLOW SECTIONS UNDER IN-PLANE BENDING
Authors: MASHIRI FIDELIS RUTENDO , ZHAO XIAO-LING , GRUNDY PAUL
Published: August 2004

The fatigue behavior of welded thin-walled T-joints made up of both circular hollow section (CHS) braces and chords, subjected to cyclic in-plane bending, is described in this paper. CHS chords and braces are of thicknesses less than 4 mm. Current fatigue design guidelines show that the design of welded tubular nodal joints is restricted to thicknesses greater than or equal to 4 mm. The increased availability and use of thin-walled (t<4 mm) tubes of high-strength steels in recent years, in structures subjected to cyclic loading, means that it is important to study the fatigue behavior of welded thin-walled tubular nodal joints. In this paper, welded thin-walled CHS-CHS T-joints subjected to constant-stress-amplitude cyclic in-plane bending range are studied. The stress concentration factors (SCFs) determined experimentally at the brace and chord crown positions are shown to be about 30% and 40% respectively of the SCFs determined using parametric equations in existing fatigue design guidelines. The fatigue tests showed that in welded thin-walled CHS-CHS T-joints, a through-thickness crack occurs when the surface crack length along the weld toes in the chord has grown to a length equal to about 40% of the circumference of the brace member. An end of test failure criterion was proposed as an alternative to the through-thickness failure criterion, in obtaining data that is suitable for determining fatigue design S-N curves.
DEVELOPMENT OF 3D ELASTODYNAMIC INFINITE ELEMENTS FOR SOIL-STRUCTURE INTERACTION PROBLEMS
Authors: PARK KYOUNG-LAE , WATANABE EIICHI , UTSUNOMIYA TOMOAKI
Published: August 2004

This paper presents three-dimensional (3D) infinite elements for the multi-layered elastodynamics problems. There are three types of elements, namely horizontal, vertical and corner elements. They have been developed using wave functions in function spaces that can simulate real wave problems properly. The elements are extended forms of the axisymmetric infinite elements developed previously. Since these elements can simulate multiple layers and multiple wave numbers, the response of a 3D general structural system considering soil-structure interaction effect can be determined effectively. Numerical analyses are carried out for a rigid massless disk and square footings on the surface of various layer conditions for verification purposes. The calculated results are compared with existing analytical and numerical data and they were found to be in good agreement.
FREE VIBRATIONS OF HOMOGENEOUS AND LAYERED PIEZOELECTRIC HOLLOW SPHERES
Authors: RAMIREZ GUILLERMO , BUCHANAN GEORGE
Published: August 2004

A finite element formulation in spherical coordinates is presented for the study of the vibrations of piezoelectric homogeneous and layered hollow spheres. The finite element model is based on nine-node Lagrangian interpolation functions. Representative cases are considered including solid elastic spheres and hollow homogeneous and laminated piezoelectric spheres. The accuracy of the proposed formulation is verified by comparison with existing solutions showing excellent agreement. Several new results are presented for different piezoelectric materials in both tabular and graphical format.
EQUI-ATTRACTION AND THE CONTINUOUS DEPENDENCE OF PULLBACK ATTRACTORS ON PARAMETERS
Authors: LI DESHENG , KLOEDEN P. E.
Published: August 2004

The equi-attraction properties of uniform pullback attractors [Formula: see text] of nonautonomous dynamical systems (θ,ϕλ) with a parameter λ∈Λ, where Λ is a compact metric space, are investigated; here θ is an autonomous dynamical system on a compact metric space P which drives the cocycle ϕλon a complete metric state space X. In particular, under appropriate regularity conditions, it is shown that the equi-attraction of the family [Formula: see text] uniformly in p∈P is equivalent to the continuity of the setvalued mappings [Formula: see text] in λ with respect to the Hausdorff metric on the nonempty compact subsets of X.
TOWARDS A MORSE THEORY FOR RANDOM DYNAMICAL SYSTEMS
Authors: CRAUEL HANS , DUC LUU HOANG , SIEGMUND STEFAN
Published: August 2004

A generalization of the concepts of deterministic Morse theory to random dynamical systems is presented. Using the notions of attraction and repulsion in probability, the main building blocks of Morse theory such as attractor–repeller pairs, Morse sets, and the Morse decomposition are obtained for random dynamical systems.
ROBUST ASYMPTOTIC CONTROLLABILITY UNDER TIME-VARYING PERTURBATIONS
Authors: GRÜNE LARS
Published: August 2004

We investigate the effect of time-varying perturbations on the dynamical behavior of nonlinear control systems. More specifically, we study the effect of such perturbations on the controlled equivalent of asymptotically stable sets, i.e. asymptotically controllable sets. In the first part of this paper we illustrate by a simple example how different types of perturbations affect this dynamical behavior and use concepts from dynamical game theory in order to identify classes of perturbations which allow to model the effects of numerical discretization errors both in time and space. In the second part we introduce appropriate robustness properties and prove that these are inherent properties for asymptotically controllable sets under these classes of perturbations.
A CONTRIBUTION TO NONAUTONOMOUS INERTIAL MANIFOLDS
Authors: KOKSCH NORBERT
Published: August 2004

The goal of the paper is to construct nonautonomous inertial manifolds via outflowing invariant manifolds. As an example, a nonautonomous, nonlocal Burgers equation is considered.
A NONAUTONOMOUS SADDLE-NODE BIFURCATION PATTERN
Authors: FABBRI ROBERTA , JOHNSON RUSSELL , MANTELLINI FRANCESCA
Published: August 2004

In this paper we study certain differential equations depending on a small parameter ε which exhibit a bifurcation of saddle-node type as ε passes through zero. We use a classical averaging technique together with methods and results from the modern theory of nonautonomous differential equations.
ALMOST ALL NONAUTONOMOUS LINEAR STOCHASTIC DIFFERENTIAL EQUATIONS ARE REGULAR
Authors: CONG NGUYEN DINH
Published: August 2004

We prove that almost all nonautonomous linear stochastic differential equations are Lyapunov regular.
FINITE DIMENSIONALITY OF ATTRACTORS FOR NON-AUTONOMOUS DYNAMICAL SYSTEMS GIVEN BY PARTIAL DIFFERENTIAL EQUATIONS
Authors: LANGA J. A. , SCHMALFUSS B.
Published: August 2004

In the last decade, the concept of pullback attractor has become one of the usual tools to describe some qualitative properties of non-autonomous partial differential equations. A pullback attractor is a family of compact sets, invariant for the corresponding process related to the equation, and attracting from the past, and it assumes a natural generalization of the now classical concept of global attractor for autonomous partial differential equations. In this work we give sufficient conditions in order to prove the finite Hausdorff and fractal dimensionality of pullback attractors for non-autonomous infinite dimensional dynamical systems, and we apply our results to a generalized non-autonomous partial differential equation of Navier–Stokes type.
PULLBACK AND FORWARD ATTRACTORS FOR A DAMPED WAVE EQUATION WITH DELAYS
Authors: CARABALLO T. , KLOEDEN P. E. , REAL J.
Published: August 2004

The existence of a pullback (and also a uniform forward) attractor is proved for a damped wave equation containing a delay forcing term which, in particular, covers the models of sine–Gordon type. The result follows from the existence of a compact set which is uniformly attracting for the two-parameter semigroup associated to the model.
ATTRACTING SETS IN COCYCLE DELAY DIFFERENTIAL EQUATIONS AND IN THEIR RUNGE–KUTTA DISCRETIZATIONS
Authors: SCHROPP JOHANNES
Published: August 2004

We investigate the discretization of nonautonomous cocycle delay differential equations near uniform pullback attractors of arbitrary shape and show that for sufficiently small step sizes a Runge–Kutta discretization admits a discrete uniform pullback attractor located close to that of the original system.
INVARIANT MEASURES AND THEIR PROJECTIONS IN NONAUTONOMOUS DYNAMICAL SYSTEMS
Authors: ARTSTEIN ZVI
Published: August 2004

Invariant measure-type notions are examined for nonautonomous dynamical systems, namely, for flows whose dynamics is affected by an external parameter. The desired measures are obtained as projections of invariant measures of the shift flow on the lifted space of trajectories. The specific cases of multi-valued dynamics and controlled dynamics are examined in detail and other applications are pointed out.
ON LIPSCHITZ CONTINUITY OF THE TOP LYAPUNOV EXPONENT OF LINEAR PARAMETER VARYING AND LINEAR SWITCHING SYSTEMS
Authors: WIRTH FABIAN
Published: August 2004

We study families of time-varying linear systems, where time-variations have to satisfy restrictions on the dwell time, that is, on the minimum distance between discontinuities, as well as on the derivative in between discontinuities. For this class of systems we study continuity properties of the growth rate as a function of the systems' data. It is shown by example, that a straightforward topology on the space of systems does not yield the desired continuity result. A new natural metric is introduced and a continuity result is obtained. Furthermore, local Lipschitz continuity may be shown for the (generic) case of irreducible systems. The methods rely heavily on a recent converse Lyapunov theorem for the class under consideration.
FREQUENCY DOMAIN CONDITIONS FOR THE EXISTENCE OF ALMOST PERIODIC SOLUTIONS IN EVOLUTIONARY VARIATIONAL INEQUALITIES
Authors: REITMANN VOLKER , KANTZ HOLGER
Published: August 2004

Evolutionary variational inequalities are considered as control systems in a general rigged Hilbert space structure. Sufficient frequency domain conditions for boundedness and the existence of periodic and almost periodic solutions are derived. As an example a boundary control problem with periodic excitation function is considered.
Organisational Learning in the Context of Strategic Reorientation
Authors: Lines Rune , Johansen Svein Tvedt , Døving Erik
Published: August 2004

This study tested the influences of change novelty, participation and goal setting on organisational learning. The study was conducted following the strategic reorientation of a large telecommunication firm. Major findings were: (1) Participation in strategic change is positively related to organisational learning; (2) the use of goal setting as part of the implementation process enhances organisational learning; and (3) medium and high levels of change novelty is associated with higher levels of learning than low levels of change novelty.
Managing Knowledge Strategically: A Comparison of Managers' Perceptions between the Private and Public Sector in Australia
Authors: Zhou Albert Z.
Published: August 2004

This paper compares the perceptions of private and public sector managers in regard to knowledge management (KM), using data derived from a survey conducted in Australia. The objective is to develop understanding of the current practice to assist in developing strategies to improve public sector KM practice. Findings revealed that public sector respondents in Australia had a less developed understanding in KM and intellectual capital (IC), as compared to the private sector respondents. This poorer understanding had led to a much weaker KM practice in the public sector: KM initiatives were not commonly addressed at the strategic level; employees were less trained and developed; few measurement systems were developed and almost no incentive and reward measures were established. In addition, public sector respondents were less confident about the roles of organisational culture, organisational structure and IT in KM in their organisation. They had lower agreement on the role of organisational structure, culture and IT as knowledge creation and sharing facilitators. The study, to a certain extent, supports the proposition that industrial context has an effect on managers' perceptions of KM.
Team Coordination, Communication and Knowledge Sharing in SMEs and Large Organisations
Authors: Steinheider Brigitte , Al-Hawamdeh Suliman
Published: August 2004

Knowledge has become more and more the prime resource for companies due to innovative pressure and the increasing importance of knowledge work. To maximize the innovative potential, companies are challenged to share and integrate the knowledge of their employees in project and product development teams. Knowledge sharing thus becomes essential for the success of product development and business processes. However, research has revealed that collaboration and knowledge sharing in organisations are often problematic. In this paper we investigated the impact of organisational size and team structure on team coordination, communication and knowledge sharing in German R&D departments, as well as department heads' satisfaction with team performance. Results show that communication, coordination and knowledge sharing problems correlate with the size of the organisation and the structure of teams. Department heads in small and medium size enterprises with more dynamic structures indicate fewer collaboration problems in their product development teams and higher satisfaction with team performance compared to department heads in large enterprises. These findings emphasize the influence of structural factors on knowledge sharing processes and link knowledge sharing with outcome factors such as supervisors' satisfaction with team performance.
In Search of the Total Learning Experience (TLE): A Case Study of Singapore's e-Inclusive Society
Authors: Lim Eric T. K. , Weber Ian
Published: August 2004

This paper re-visits the ongoing e-learning phenomenon from a holistic perspective through the study of the world's first nationwide, e-inclusive society in Singapore. It draws upon the current literature for learning models, knowledge management and utilization of technology for electronic education to examine the contribution Singapore's National IT Literacy Program (NITLP) has made to drive the diffusion of Internet, broadband and e-transaction adoption in this island nation. In doing so, the case study tracks NITLP's development of continuous and progressive phases of infrastructure, infostructure and knowledge-structure integration to leverage Information and Communication Technologies (ICTs) more efficiently and effectively for the delivery of a holistic learning experience for Singapore's late IT adopters. The practical application of the implementation program is the provision of an evaluative tool for e-learning practitioners to enable an upward spiral of continuous feedback and improvements to the e-learning architecture and contribute more strategically to the development of a total learning experience. For the learner, the model generates strategic value from knowledge creating and sharing activities. The lessons learnt from Singapore's approach to developing its e-inclusive society are significant beyond just the experience of this island nation, as it serves as an indicator of how countries in the Asia-Pacific and internationally can conceptualize and implement national IT literacy programs within a framework of e-inclusive societies to promote knowledge-based economies.
Efficient Mining of Frequent Itemsets and a Measure of Interest for Association Rule Mining
Authors: Ahn Kwang-Il , Kim Jae-Yearn
Published: August 2004

Association rule mining is an important research topic in data mining. Association rule mining consists of two steps: finding frequent itemsets and then extracting interesting rules from the frequent itemsets. In the first step, efficiency is important since discovering frequent itemsets is computationally time consuming. In the second step, unbiased assessment is important for good decision making.

In this paper, we deal with both the efficiency of the mining algorithm and the measure of interest of the resulting rules. First, we present an algorithm for finding frequent itemsets that uses a vertical database. We also introduce a modified vertical data format to reduce the size of the database and an itemset reordering strategy to reduce the size of the intermediate tidsets. Second, we present a new measure to evaluate the interest of the resulting association rules. Our performance analysis shows that our proposed algorithm reduces the size of the intermediate tidsets that are generated during the mining process. The smaller tidsets make intersection operations faster. Using our interest-measuring test helps to avoid the discovery of misleading rules.
Leveraging Cognition for Competitive Advantage: A Knowledge-Based Strategy Process
Authors: Muthusamy Senthil K. , Palanisamy Ramaraj
Published: August 2004

The organisation that wants to build competitive advantages has to create and leverage its capabilities. One of the central bases for achieving competitive advantage is the organisational capability to create new knowledge and transfer it across various levels and parts of the organisation. Because knowledge is central to strategy formulation and implementation, knowledge management has become a key strategic task facing managers for achieving success in today's complex and dynamic environments. A major challenge facing strategic management is engineering and managing the individual and group level knowledge that facilitates better strategies and invokes commitment. A knowledge management based model of strategy formulation process is presented. Traditional strategy frameworks are evaluated and a comprehensive cognition and learning centered strategy framework is suggested as a better model of strategy formulation and implementation for achieving competitive advantage. The implications of the knowledge-based approach for strategic management practice and research are highlighted.