bluuebunny/crossref_metadata_2025 huggingface dataset:
Architecture of silver maple and its response to pruning near the power distribution network
Authors: Millet Jeanne , Bouchard André
Published: March 2003

The architectural analysis of silver maple (Acer saccharinum L.) in natural environments has revealed the sympodial nature of its growth, the three levels of organization that govern the development of its stems through an alternation of organization plans (hierarchic and polyarchic), as well as the characteristic traits of the three architectural units involved and of the four categories of differentiated axes. The growth responses of silver maple alongside streets were analyzed in four pruning contexts associated with tree position relative to the wires of the power distribution network. Data reveal that with increasing pruning pressure, the percentage of the crown composed of suckers becomes higher, as does their growth rate, indicating a greater disorganization of the structure of the crown. Silver maple is naturally capable of developing a low fork with limbs that have hierarchic development. However, the pruning has promoted the reverse, which is the appearance of a high fork and, after repeated prunings, a more polyarchic development of the crown, increasing the threat that trees represent for wires.
Spatial pattern of invading Dendroctonus micans (Coleoptera: Scolytidae) populations in the United Kingdom
Authors: Gilbert M , Fielding N , Evans H F , Grégoire J -C
Published: March 2003

The spatial pattern of Dendroctonus micans (Kug.) attacks on individual spruce stands was analysed at the regional scale in Britain using data collected between 1982 and 1984 by the British Forestry Commission. These survey data reflect at least 10 years of D. micans spread, in the absence of natural enemies and of pest management control measures. A large-scale spatial gradient in the attack density at the stand level was identified and modelled. The large-scale spatial trend model explained 31.3% of the variability, and divided the study area in three separate areas: a zone where the insect was well established and where attack density presented low variations, a transition zone where attack density sharply decreased, and a zone not yet colonized. Attack density was related to site and stand factors, and to landscape neighbourhood in a linear spatial regression model. The factors correlated to attack density and the spatial autocorrelation structure of remaining variability were found to vary according to the zones, reflecting the predominance of different ecological processes occurring in colonized and uncolonized areas. The shape and orientation of the large-scale spatial model was shown to be mostly influenced by the spatial distribution of early attacks.
Modeling Pinus strobus mortality following prescribed fire in Quetico Provincial Park, northwestern Ontario
Authors: Beverly Jennifer L , Martell David L
Published: March 2003

In forest ecosystems where ecologically beneficial fire impacts are promoted through the use of prescribed fire, predictive models of fire effects, such as tree mortality, are essential for assessing the ecological consequences of fire management options. Impact of tree size, fire intensity, and fuel characteristics on postfire eastern white pine (Pinus strobus L.) mortality was evaluated 10 months following a prescribed fire in Quetico Provincial Park, northwestern Ontario. A logistic regression model was developed to predict white pine mortality following an intense surface fire (1200 kW/m). Overall fire-caused mortality was relatively low (17.0%). Probability of mortality increased with increasing height of stem blackening, a surrogate measure of fire intensity, and decreased with increasing tree diameter at 1.3 m (DBH). White pine with [Formula: see text]20 cm DBH were found to be highly resistant to intense surface fire. The model can be used to predict postfire mortality in white pine stands with a mixedwood understory in the Great Lakes  St. Lawrence forest region of Ontario.
Coarse-scale population structure of pathogenicArmillariaspecies in a mixed-conifer forest in the Blue Mountains of northeast Oregon
Authors: Ferguson B A , Dreisbach T A , Parks C G , Filip G M , Schmitt C L
Published: March 2003

The coarse-scale population structure of pathogenic Armillaria (Fr.) Staude species was determined on approximately 16 100 ha of relatively dry, mixed-conifer forest in the Blue Mountains of northeast Oregon. Sampling of recently dead or live, symptomatic conifers produced 112 isolates of Armillaria from six tree species. Armillaria species identifications done by using a polymerase chain reaction based diagnostic and diploiddiploid pairings produced identical results: 108 of the isolates were Armillaria ostoyae (Romagn.) Herink and four were North American Biological Species X (NABS X). Five genets of A. ostoyae and one of NABS X were identified through the use of somatic incompatibility pairings among the putatively diploid isolates. Armillaria ostoyae genet sizes were approximately 20, 95, 195, 260, and 965 ha; cumulative colonization of the study area was at least 9.5%. The maximum distance between isolates from the 965-ha A. ostoyae genet was approximately 3810 m, and use of three estimates of A. ostoyae spread rate in conifer forests resulted in age estimates for the genet ranging from 1900 to 8650 years. Results are discussed in relation to possible mechanisms that influenced the establishment, expansion, and expression of these genets; the genetic structure and stability of Armillaria; and the implications for disease management in this and similar forests.
NEW MINIMUM UNCERTAINTY STATES FOR THERMO FIELD DYNAMICS
Authors: FAN HONGYI
Published: March 2003

In Takahashi–Umezawa Thermo Field Dynamics theory every operator a acting on real field space is accompanied by its image ã acting on fictitious field space, we propose a new uncertainty relation which embodies the finite temperature effect and derive the corresponding minimum uncertainty state — a new thermolized two-variable Hermite polynomial state.
RESIDUAL SYMMETRIES IN THE PRESENCE OF AN EM BACKGROUND
Authors: CARRION H. L. , ROJAS M. , TOPPAN F.
Published: April 2003

The symmetry algebra of a QFT in the presence of an external EM background (named "residual symmetry") is investigated within a Lie-algebraic, model-independent scheme. Some results previously encountered in the literature are extended here. In particular we compute the symmetry algebra for a constant EM background in D = 3 and D = 4 dimensions. In D = 3 dimensions the residual symmetry algebra, for generic values of the constant EM background, is isomorphic to [Formula: see text], with [Formula: see text] the centrally extended two-dimensional Poincaré algebra. In D = 4 dimension the generic residual symmetry algebra is given by a seven-dimensional solvable Lie algebra which is explicitly computed. Residual symmetry algebras are also computed for specific non-constant EM backgrounds and in the supersymmetric case for a constant EM background. The supersymmetry generators are given by the "square roots" of the deformed translations.
ALGEBRA OF CHIRAL CURRENTS ON THE PHYSICAL SURFACE
Authors: AMÉZAGA ALEXIS , LEIVA CARLOS
Published: April 2003

Using a particular structure for the Lagrangian action in a one-dimensional Thirring model and performing the Dirac's procedure, we are able to obtain the algebra for chiral currents which is entirely defined on the constraint surface in the corresponding Hamiltonian description of the theory.
IMPLEMENTING POWER LAW INFLATION WITH TACHYON ROLLING ON THE BRANE
Authors: SAMI M.
Published: March 2003

We study a minimally coupled tachyon field rolling down to its ground state on the FRW brane. We construct tachyonic potential which can implement power law inflation in the brane world cosmology. The potential turns out to be V0ϕ-1 on the brane and reduces to inverse square potential at late times when brane corrections to the Friedmann equation become negligible. We also do similar exercise with a normal scalar field and discover that the inverse square potential on the brane leads to power law inflation.
TWO-PHOTON DECAY RATES OF HEAVY QUARKONIA IN THE RELATIVISTIC QUARK MODEL
Authors: EBERT D. , FAUSTOV R. N. , GALKIN V. O.
Published: April 2003

Two-photon decay rates of pseudoscalar, scalar and tensor states of charmonium and bottomonium are calculated in the framework of the relativistic quark model. Both relativistic effects and one-loop radiative corrections are taken into account. The obtained results are compared with other theoretical predictions and available experimental data.
UNIVERSAL CALABI–YAU ALGEBRA: CLASSIFICATION AND ENUMERATION OF FIBRATIONS
Authors: ANSELMO F. , ELLIS J. , VOLKOV G. , NANOPOULOS D. V.
Published: March 2003

We apply a universal normal Calabi–Yau algebra to the construction and classification of compact complex n-dimensional spaces with SU (n) holonomy and their fibrations. This algebraic approach includes natural extensions of reflexive weight vectors to higher dimensions and a "dual" construction based on the Diophantine decomposition of invariant monomials. The latter provides recurrence formulas for the numbers of fibrations of Calabi–Yau spaces in arbitrary dimensions, which we exhibit explicitly for some Weierstrass and K3 examples.
TWO-DIMENSIONAL GRAVITY WITH AN INVARIANT ENERGY SCALE AND ARBITRARY DILATON POTENTIAL
Authors: MIGNEMI S.
Published: April 2003

We investigate a model of two-dimensional gravity with arbitrary scalar potential obtained by gauging a deformation of de Sitter or more general algebras, which accounts for the existence of an invariant energy scale. We obtain explicit solutions of the field equations and discuss their properties.
HAVE WE OBSERVED THE SKIN VIBRATION OF REALISTIC STRANGE STARS (ReSS)?
Authors: SINHA MONIKA , DEY JISHNU , DEY MIRA , RAY SUBHARTHI , BHOWMICK SIDDHARTHA
Published: April 2003

Skin vibration of ReSS and consequent resonance absorption can account for the absorption lines in the spectrum of X-ray emission from many compact stellar objects and in particular, the stars J1210-5226 and RXJ1856-3754. Observations of the X-ray spectrum of these stars is difficult to explain, if they are neutron stars.
BULK SHAPE OF BRANE-WORLD BLACK HOLES
Authors: CASADIO ROBERTO , MAZZACURATI LORENZO
Published: April 2003

We propose a method to extend to the bulk asymptotically flat static spherically symmetric brane-world metrics. We employ the multipole (1/r) expansion in order to allow the exact integration of the relevant equations along the (fifth) extra coordinate and make contact with the parametrized post-Newtonian formalism. We apply our method to three families of solutions previously appeared as candidates of black holes in the brane world and show that the shape of the horizon is very likely a flat "pancake" for astrophysical sources.
EARLY-UNIVERSE PHASE TRANSITIONS AND YANG–MILLS THEORIES
Authors: HWANG W.-Y. PAUCHY
Published: April 2003

Our universe expands and cools. The electroweak (EW) phase transition, which endows masses to the various particles, and QCD phase transition, which gives rise to confinement of quarks and gluons within hadrons in the true QCD vacuum, would presumably have taken place in the early universe, respectively, at around 10-11 s and at a time between 10-5 s and 10-4 s, or at the temperature of about 300 GeV and of about 150 MeV, respectively. There is little doubt that much of what we see today is rooted in phase transitions in the early Universe, overturns of our universe from one phase to a completely different phase. We wish to stress here that occurrence of such phase transitions is closely tied to our Nature's realization of Yang–Mills gauge theories at the moment of creation.
LOCAL CONTRIBUTION OF A QUANTUM CONDENSATE TO THE VACUUM ENERGY DENSITY
Authors: MODANESE GIOVANNI
Published: April 2003

We evaluate the local contribution gμνL of coherent matter with Lagrangian density L to the vacuum energy density. Focusing on the case of superconductors obeying the Ginzburg–Landau equation, we express the relativistic invariant density L in terms of low-energy quantities containing the pairs density. We discuss under which physical conditions the sign of the local contribution of the collective wave function to the vacuum energy density is positive or negative. Effects of this kind can play an important role in bringing the local changes in the amplitude of gravitational vacuum fluctuations — a phenomenon reminiscent of the Casimir effect in QED.
GHOST CONDENSATES IN YANG–MILLS THEORIES IN NONLINEAR GAUGES
Authors: LEMES V. E. R. , SARANDY M. S. , SORELLA S. P. , PICARIELLO M. , FAZIO A. R.
Published: April 2003

Ghost condensates of dimension two are analyzed in a class of nonlinear gauges in pure Yang–Mills theories. These condensates are related to the breaking of the SL (2, R) symmetry, present in these gauges.
RENORMALIZATION GROUP EQUATION OF QUARK–LEPTON MASS MATRICES IN THE SO(10) MODEL WITH TWO-HIGGS SCALARS
Authors: FUKUYAMA TAKESHI , KIKUCHI TATSURU
Published: April 2003

The renormalization group equations (RGEs) of the mass matrices of quarks and leptons in an SO(10) model with two-Higgs scalars in the Yukawa coupling are studied. This model is the minimal model of SUSY and non-SUSY SO(10) GUT which can reproduce all the experimental data. Non-SUSY SO(10) GUT model has the intermediate energy phase, Pati–Salam phase, and passes through the symmetry breaking pattern, SO (10) → SU (2)L × SU (2)R × SU (4)C → SU (2)L × U (1)Y × SU (3)C. Though minimal, it has, after the Pati–Salam phase, four Higgs doublets in Yukawa interactions. We consider the RGEs of the Yukawa coupling constants of quarks and charged leptons and of the coupling constants of the dimension-five operators of neutrinos corresponding to the above symmetry breaking pattern. The scalar quartic interactions are also incorporated.
RESIDUAL SMALLNESS AND WEAK CENTRALITY
Authors: KEARNES KEITH A. , KISS EMIL W.
Published: March 2003

We develop a method of creating skew congruences on subpowers of finite algebras using groups of twin polynomials, and apply it to the investigation of residually small varieties generated by nilpotent algebras. We prove that a residually small variety generated by a finite nilpotent (in particular, a solvable E-minimal) algebra is weakly abelian. Conversely, we show in two special cases that a weakly abelian variety is residually bounded by a finite number: when it is generated by an E-minimal, or by a finite strongly nilpotent algebra. This establishes the RS-conjecture for E-minimal algebras.
THE p-COCKCROFT PROPERTY OF THE SEMI-DIRECT PRODUCTS OF MONOIDS
Authors: ÇEVIK A. SINAN
Published: March 2003

The semi-direct product of arbitrary two monoids and a presentation for this product have received considerable attention, see for instance [12, 14, 15]. In [15], Wang defined a trivializer set of the Squier complex associated with this presentation. In this paper, as a main result, we discuss necessary and sufficient conditions for the standard presentation of the semi-direct product of any two monoids to be p-Cockcroft for any prime p or 0. Finally we present some applications of this main theorem.
THE BINARY ADDING MACHINE AND SOLVABLE GROUPS
Authors: SIDKI SAID
Published: March 2003

We prove that any solvable subgroup K of automorphisms of the binary tree, which contains the binary adding machine is an extension of a torsion-free metabelian group by a finite 2-group. If the group K is moreover nilpotent then it is torsion-free abelian.
PRIMITIVE ELEMENTS OF FREE METABELIAN ALGEBRAS OF RANK TWO
Authors: DRENSKY VESSELIN , YU JIE-TAI
Published: March 2003

Let F(x,y) be a relatively free algebra of rank 2 in some variety of algebras over a field K of characteristic 0. In this paper we consider the problem whether p(x,y) ∈ F(x,y) is a primitive element (i.e. an automorphic image of x): (i) If F(x,y)/(p(x,y)) ≅ F(z), the relatively free algebra of rank 1 (ii) If p(f,g) is primitive for some injective endomorphism (f,g) of F(x,y) (iii) If p(x,y) is primitive in a relatively free algebra of larger rank. These problems have positive solutions for polynomial algebras in two variables. We give the complete answer for the free metabelian associative and Lie algebras and some partial results for free associative algebras.
FREE SUBGROUPS OF THE GROUP OF INFINITE UNITRIANGULAR MATRICES
Authors: HOŁUBOWSKI WALDEMAR
Published: March 2003

In this note we give simple explicit examples of free subgroups of rank 2 in the group of infinite upper unitriangular matrices over integers. The proofs that the given subgroup is free are elementary. Using canonical projections mod p (p — any odd prime) we obtain also free subgroups in the group of finite state automata on alphabet of size p, extending results of Aleshin [1], Brunner–Sidki [2] and Olijnyk–Sushchansky [8, 9] in this direction. As application, we give the simple proofs of two classical results on free groups.
COMPLETE SYSTEMS OF SUBALGEBRAS
Authors: KISIELEWICZ ANDRZEJ
Published: March 2003

In the 1960s, G. Grätzer introduced the notion of the minimal extension property (MEP) of a finite sequence in order to investigate pn-sequences and free spectra of algebras. While there are many particular results on the MEP, stating that some sequences or families of sequences have the MEP, no general result has been obtained so far and the main general problems remain open.

In this paper we prove a fact about existence of finite complete systems of subalgebras, which generalizes a method used occasionally to prove the minimal extension property of a sequence. Using this we obtain some general results about minimal extensions and, along the way, a rather unexpected solution of one of the central open problems in the area.
BREADTH-FIRST SEARCH AND THE ANDREWS–CURTIS CONJECTURE
Authors: HAVAS GEORGE , RAMSAY COLIN
Published: March 2003

Andrews and Curtis conjectured in 1965 that every balanced presentation of the trivial group can be transformed into a standard presentation by a finite sequence of elementary transformations. Recent computational work by Miasnikov and Myasnikov on this problem has been based on genetic algorithms. We show that a computational attack based on a breadth-first search of the tree of equivalent presentations is also viable, and seems to outperform that based on genetic algorithms. It allows us to extract shorter proofs (in some cases, provably shortest) and to consider the length thirteen case for two generators. We prove that, up to equivalence, there is a unique minimum potential counterexample.
A NEW CLASS OF RIGID COXETER GROUPS
Authors: BAHLS PATRICK
Published: March 2003

A Coxeter group is said to be rigid if any two systems for that group yield isomorphic Coxeter diagrams. A Coxeter group is said to be strongly rigid if moreover the generating sets of any two systems are conjugate. We determine a new class of Coxeter groups which are rigid, and introduce the notion of reflection independence, a generalization of strong rigidity.
QUANDLES AT FINITE TEMPERATURES I
Authors: LOPES PEDRO
Published: April 2003

In [3] quandle cohomology is used to produce invariants for particular embeddings of codimension two; 2-cocycles give rise to invariants for (classical) knots and 3-cocycles give rise to invariants for knotted surfaces. This is done by way of a notion of coloring of a diagram. Also, these invariants have the form of the state-sums (or partition functions) used in Statistical Mechanics.

By a careful analysis of these colorings of diagrams we are able to come up with new invariants which correspond to calculation of the partition function at finite temperatures.
THE NONCOMMUTATIVE A-IDEAL OF A (2, 2p + 1)-TORUS KNOT DETERMINES ITS JONES POLYNOMIAL
Authors: GELCA RĂZVAN , SAIN JEREMY
Published: April 2003

The noncommutative A-ideal of a knot is a generalization of the A-polynomial, defined using Kauffman bracket skein modules. In this paper we show that any knot that has the same noncommutative A-ideal as the (2,2p + 1)-torus knot has the same colored Jones polynomials. This is a consequence of the orthogonality relation, which yields a recursive relation for computing all colored Jones polynomials of the knot.
LOOPS AND DISKS IN SURFACES AND HANDLEBODIES
Authors: ZABLOW JOEL
Published: April 2003

We consider a groupoid structure involving graphs and imbedded circles (resp. disks) in a closed orientable surface F (resp. the handleboby H it bounds). We look at generalized connected sums and related operations "induced" by certain morphisms, and introduce a quandle structure involving isotopy classes of imbedded circles and Dehn twists in F. Some relations between these operations are examined, and we look at characterizations of imbedded disks in H arising in this algebraic context.
SIMPLE NON-FINITE KNOTS ARE NOT PRIME IN HIGHER DIMENSIONS
Authors: KEARTON C. , WILSON S. M. J.
Published: April 2003

It has long been known that in high dimensions tbere are examples of irreducible knots which are not prime. Here we show that in fact there are no prime simple knots in high dimensions, with the possible exception of those whose homology is finite. In particular, the result holds for all simple (2q - 1)-knots, q > 1.
TOPOLOGICAL PROPERTIES OF CYCLICALLY PRESENTED GROUPS
Authors: CAVICCHIOLI ALBERTO , REPOVŠ DUŠAN , SPAGGIARI FULVIA
Published: April 2003

We introduce a family of cyclic presentations of groups depending on a finite set of integers. This family contains many classes of cyclic presentations of groups, previously considered by several authors. We prove that, under certain conditions on the parameters, the groups defined by our presentations cannot be fundamental groups of closed connected hyperbolic 3–dimensional orbifolds (in particular, manifolds) of finite volume. We also study the split extensions and the natural HNN extensions of these groups, and determine conditions on the parameters for which they are groups of 3–orbifolds and high–dimensional knots, respectively.
NORMAL SURFACES IN THE FIGURE-8 KNOT COMPLEMENT
Authors: KANG ENSIL
Published: April 2003

An approach to normal surface theory for non-compact 3-manifolds with respect to ideal pseudo-triangulations is described in [12]. The figure-8 knot complement with a given ideal pseudo-triangulation with two ideal tetrahedra is fully worked out. We construct all Q-fundamental surfaces and the remaining normal surfaces are obtained by linear geometric sums of these. We also construct all almost normal surfaces in the figure-8 knot complement. As a result we obtain an example which does not contain any normal or almost normal surface representing a minimal Seifert surface of the knot. This leads that the figure-8 knot is fibered.
HOW SMOOTH IS A DEVIL'S STAIRCASE?
Authors: DEKKING F. M. , LI WENXIA
Published: April 2003

Let the self-similar set C in R be defined by [Formula: see text] with a disjoint union, where the hj's are similitude mappings with ratios 0 < aj < 1. Let μ on C be the self-similar probability measure corresponding to the probability vector [Formula: see text], where ξ = dim HC is the Hausdorff dimension of C. Let S be the set of points at which the probability distribution function F of μ has no derivative, finite or infinite. We prove that dim H S = ( dim HC)2 and dim P S = dim B S = dim HC.
FRACTALS IN A FIRST YEAR UNDERGRADUATE SEMINAR
Authors: HUGHES JAMES R.
Published: April 2003

The study of basic fractal geometry can help build students' enthusiasm for learning early in their undergraduate careers. To most undergraduate students, fractals are new, visually appealing, useful, and mathematically accessible. As a result, fractals can be an effective vehicle for introducing and reinforcing multiple modes of learning, which at many institutions is one of the main goals of general first-year undergraduate education. This article describes how fractals are used in one institution's "Freshman Seminar" program to help accomplish these goals.
FRACTAL PROPERTIES, SEGMENT ANATOMY, AND INTERDEPENDENCE OF THE HUMAN PORTAL VEIN AND THE HEPATIC VEIN IN 3D
Authors: HAHN HORST K. , EVERTSZ CARL J. G. , PEITGEN HEINZ-OTTO , FASEL JEAN H. D.
Published: March 2003

The scaling properties of the portal vein and the hepatic vein are examined, based on three-dimensional computed tomography images of casts of human livers. In particular, a quantitative analysis of the branching ratio based on the Strahler ordering scheme as well as the diameter and length ratios are performed. To quantify the segment anatomy of the liver, the volume of supplied liver parenchyma is measured and related to the corresponding vessel radius. The implications of these findings for segment-oriented liver surgery are discussed. We also investigate the 3D interdependence of the intertwined portal and hepatic veins based on a concept of tree distance that will be introduced.
THE EXQUISITE GEOMETRIC STRUCTURE OF A CENTRAL LIMIT THEOREM
Authors: PUENTE CARLOS E.
Published: April 2003

Universal constructions of univariate and bivariate Gaussian distributions, as transformations of diffuse probability distributions via, respectively, plane- and space-filling fractal interpolating functions and the central limit theorems that they imply, are reviewed. It is illustrated that the construction of the bivariate Gaussian distribution yields exotic kaleidoscopic decompositions of the bell in terms of exquisite geometric structures which include non-trivial crystalline patterns having arbitrary n-fold symmetry, for any n > 2. It is shown that these results also hold when fractal interpolating functions are replaced by a more general class of attractors that are not functions.
FRACTAL GROWTH OF ZEOLITE COATINGS PREPARED BY THE SUBSTRATE HEATING METHOD
Authors: TATLIER MELKON
Published: March 2003

The nature of the zeolite 4A coatings prepared by using the substrate heating method was investigated. It was determined that the fractal dimensions of the surfaces of the coatings varied between about 1.14 and 1.19 with respect to the coating thickness in a mesh size range of about 1.5 μm - 48.5 μm. The fractal dimension value increased to some extent for the thicker zeolite coatings. It is hypothesized that the significance of nucleation is relatively high in the substrate heating method when compared to conventional synthesis methods and this leads to zeolite coatings with fractal surfaces and intercrystal porosity.
THE HAUSDORFF DIMENSION OF SUB-SELF-SIMILAR SETS
Authors: SHINMOTO JUNKO , TAKEO FUKIKO
Published: April 2003

This paper gives a method to obtain Hausdorff dimensions of sub-self-similar sets, where the ratios of similitudes are different. By using Gibbs measure and pressure in the sense of thermodynamic formalism, we obtain the Hausdorff dimensions of sub-self-similar sets in the space of infinite sequences. We then consider sub-self-similar sets in Rd and show how to calculate their Hausdorff dimensions under an open set condition.
SOME RESULTS OF CONVERGENCE OF CUBIC SPLINE FRACTAL INTERPOLATION FUNCTIONS
Authors: NAVASCUÉS M. ANTONIA , SEBASTIÁN M. VICTORIA
Published: April 2003

Fractal interpolation functions (FIFs) provide new methods of approximation of experimental data. In the present paper, a fractal technique generalizing cubic spline functions is proposed. A FIF f is defined as the fixed point of a map between spaces of functions. The properties of this correspondence allow to deduce some inequalities that express the sensitivity of these functions and their derivatives to those changes in the parameters defining them. Under some hypotheses on the original function, bounds of the interpolation error for f, f′ and f′′ are obtained. As a consequence, the uniform convergence to the original function and its derivative as the interpolation step tends to zero is proved. According to these results, it is possible to approximate, with arbitrary accuracy, a smooth function and its derivatives by using a cubic spline fractal interpolation function (SFIF).
SELF-SIMILARITY LIMITS OF GENOMIC SIGNATURES
Authors: WU ZUO-BING
Published: April 2003

It is shown that metric representation of DNA sequences is one-to-one. By using the metric representation method, suppression of nucleotide strings in the DNA sequences is determined. For a DNA sequence, an optimal string length to display genomic signature in chaos game representation is obtained by eliminating effects of the finite sequence. The optimal string length is further shown as a self-similarity limit in computing information dimension. By using the method, self-similarity limits of bacteria complete genomic signatures are further determined.
MODEL THE FRACTAL COMPONENT IN HEART RATE VARIABILITY AS A DYADIC BOUNDED CASCADE
Authors: LIN D. C.
Published: April 2003

The fractal component in the long-term heart rate variability (HRV) in health and in certain heart disease conditions were studied in the framework of dyadic random bounded cascade. The physiology of the fractal component was also proposed and tested in the simulation of HRV in autonomic nervous system blockade. Numerical results suggest the intrinsic mechanism behind HRV is of multiplicative nature and a "failure mechanism" due to the change of the fractal generating mechanism in certain heart diseases and in autonomic blockade.
ON THE MINKOWSKI DIMENSION OF FUNCTIONAL DIGRAPH
Authors: FENG ZHIGANG , CHEN GANG
Published: April 2003

Functional digraphs are sometimes fractal sets. As a special kind of fractal sets, the dimension properties of the functional digraph are studied in this paper. Firstly, the proof of a Minkowski dimension theorem is discussed and a new proof is given. Secondly, according to this dimension theorem, the Minkowski dimensions of the digraphs of the sum, deviation, product and quotient of two functions are discussed. And the relations between these Minkowski dimensions and the Minkowski dimensions of the digraphs of the two functions are established. In the conclusion, the maximum Minkowski dimension of the two functional digraphs plays a decisive part in the Minkowski dimensions of the digraphs of the sum, deviation, product and quotient of two functions.
Singapore Airlines: Accounting for Income Taxes
Authors: Kwok Winston , Ho Yew Kee
Published: April 2003

Singapore Airlines: Accounting for Income Taxes. A proposed standard on accounting for income taxes would affect the bottomline figures of many companies in Singapore, including a major international company, Singapore Airlines Ltd (SIA). Students have to assume the role of a financial analyst who would have to assess the impact of the change. This is a case that introduces some of the more contentious issues relating to deferred taxes and can be used in intermediate or advanced accounting courses, M.B.A. or executive programs, and courses in financial statement analysis. The objectives of the case are threefold. First, it helps students understand better the conceptual issues associated with deferred taxes. Secondly, it requires students to assess the impact of the proposed accounting changes on key financial figures and ratios. Thirdly, it engages the student to discuss the strategic implications of accounting standards on taxes in relation to management's ability to manage their bottomline numbers.
Gujarat Co-operative Milk Marketing Federation Ltd. (GCMMF)
Authors: Manikutty S.
Published: April 2003

Gujarat Cooperative Milk Marketing Federation (GCMMF) is a farmers' cooperative in India marketing the dairy products of the milk cooperatives in the State of Gujarat. It has been a successful enterprise, and its flagship brand Amul has become one of the best recognized brand names in India. Due to supply side difficulties thanks to the growth rate in milk procurement hitting a plateau, and intensified competition in the dairy products, GCMMF is considering diversification into processed foods such as juices, jams and sauces, possibly leveraging its name and brand image. The case describes the history of GCMMF, and the characteristics of the dairy as well as the processed foods businesses. The case also describes the organizational parameters of GCMMF to enable an assessment of its strengths and weaknesses. It ends with the question of whether to diversify, and if so, the implications; and if it does not, what it should do about its milk business.
Hi-Tech Communication Limited (HICOM)
Authors: Panda Abinash , Gupta Rajen K.
Published: April 2003

Hi-tech Communications Limited (HICOM) is an Indo-US joint venture between Communication Limited and Hi-tech Network System, incorporated in India in 1992 to provide satellite-based value-added business communications in India. It began providing satellite-based communication services in 1995. This case explores the leadership challenges and some of the organizational issues while the leader attempts systematically to develop a vision-driven strong organizational culture through various intervention mechanisms in HICOM. It is based on observations and a series of interviews conducted by the first author with the employees to explore their perceptions and feelings about the HICOM culture as experienced by them.
Qualcomm in China (A)
Authors: West Joel , Tan Justin
Published: March 2003

Case (A) is intended to introduce Qualcomm, its technology and its business model to provide c context for Qualcomm's efforts in China. It describes Qualcomm's development of CDMA and its single-minded effort to get CDMA adopted worldwide, and how the company's income (and valuation) is almost solely tied to a single technology. It also includes background on the cellular telephone industry and competing cellular technologies.
Dainik Bhaskar – Jaipur
Authors: Sinha Piyush Kumar , Pariher Kunjesh
Published: April 2003

Dainik Bhaskar, a Hindi newspaper, after achieving leadership in Madhya Pradesh, a central Indian State, is looking for growth opportunities. It is looking at the Hindi Belt and has identified Jaipur as the market to enter. Rajasthan Patrika dominates Jaipur with about 80% readership share. Dainik Bhaskar uses market research to understand and reach the readers and starts with a confirmed circulation. Within a very short time it has overhauled Rajasthan Patrika.

The case addresses the issue of identifying opportunities for growth by a language newspaper. It is unique because never before had a Hindi newspaper, and for that matter any language newspaper, gone beyond its stronghold. The case is also valuable because it indicates the detail that a company needs to bring into its marketing plan when fighting a long established competitor in a "habit" based product.

The case describes the process that Dainik Bhaskar adopted for analysing the potential in the identified markets and then choosing Jaipur as its target market. The innovative use of research to not only understand the readers but also lock them in for a long enough period to keep competition at bay is another aspect of the case. It is an instance where for the first time in India, a newspaper was launched with a confirmed circulation. The case is also unique in the sense that the launch was carried out without the support of the main daily, Rajasthan Patrika, as it was the main competitor. The case brings out the importance of following up a launch for sustaining leadership.

The case is useful in discussing the development of marketing strategies when tackling a monopolistic situation. The case can be used in marketing classes for bringing out the issues of growth, competition, product design, research, and market identification.
STABILITY CONJECTURE IN THE THEORY OF TENSEGRITY STRUCTURES
Authors: VOLOKH K. Y.
Published: April 2003

The general problem of the stability of tensegrity structures comprising struts and cables is formulated. It is conjectured that any tensegrity system with totally tensioned cables is stable independently of its topology, geometry and specific magnitudes of member forces.
EVALUATION OF MATHEMATICAL MODELS FOR PREDICTING WALKING-INDUCED VIBRATIONS OF HIGH-FREQUENCY FLOORS
Authors: PAVIC ALEKSANDAR , REYNOLDS PAUL , PRICHARD SARAH , LOVELL MATTHEW
Published: April 2003

This paper evaluates performance of three representative single-person walking excitation models which can be used to check vibration levels of high-frequency building floors accommodating highly sensitive equipment. The three models calculate vibration responses by harmonic, transient and spectral analyses, respectively.

The evaluation was based on a combined experimental and analytical work comprising modal testing of a prototype floor, repeated measurements of walking-induced vibrations, finite element modelling and model updating to match the measured modal properties. The updated and verified model was then used for the application of the three walking models results of which were then compared with their experimental counterparts.

It was found that all three models were on the "safe" side and overestimated responses measured in all response tests. However, the harmonic model which assumes high-frequency floor resonance caused by the 7th or 8th harmonic of the walking resulted in over-conservative response estimates order of magnitude higher than the maximum measured values in all response tests. Nevertheless, the model which describes walking across a high-frequency floor as pulses representing footfalls consistently overestimated responses by just about 20% and is, therefore, recommended for vibration serviceability checks of this type of floors.
APPLICATION OF THE MR LIQUIDS IN SEMI-ACTIVE CONTROL DEVICES
Authors: BARATTA ALESSANDRO , CORBI OTTAVIA
Published: April 2003

Magneto-rheological liquids are controllable liquids that under the action of a magnetic field can reversibly pass from the linear viscous liquid state with free-flow to the semi-solid one with a controlled stress-state. They are composed of typically non-colloidal magnetic micronized particles and possess a load carrying capacity higher than other, more controllable, fluids, such as electro-rheological liquids; moreover they are less sensitive to impurities and contaminations that may possibly occur in manufacturing. in the paper, the most suitable models for simulation of such devices are investigated with emphasis on evaluation of their efficiency as structural control systems.
SEISMIC ANALYSIS AND DESIGN EVALUATION OF CONTINUOUS PLATE-GIRDER BRIDGES: A CASE STUDY
Authors: NAZMY ALY S.
Published: April 2003

The currently-used AASHTO seismic design code for continuous plate-girder bridges built in areas of low to moderate seismicity is evaluated. The seismic behavior of a typical plate-girder bridge, designed according to the code, is studied in detail using a linear time-history analysis, and the peak response values of important parameters are computed. The effects of vertical ground excitation, seismic wave propagation, and change in support conditions on the bridge seismic response are investigated. The results are compared with those obtained using the current AASHTO seismic design code. The study concludes that the effect of vertical ground excitation on the plate-girder bending moments could be significant. It was found that the effect of seismic wave propagation on bending moments and shear forces in the bridge piers should be considered in the analysis of continuous plate girder bridges with several immovable supports when built in zones of low wave propagation speeds (e.g. 244 to 488 m/s). The study further concludes that AASHTO single mode spectral analysis slightly underestimates the forces in the bridge piers.
DYNAMIC AMPLIFICATION OF BRIDGE/VEHICLE INTERACTION: A PARAMETRIC STUDY FOR A SKEWED BRIDGE
Authors: ZENG HUAN , BERT CHARLES W.
Published: April 2003

The dynamic amplification of a bridge response due to moving vehicles has been the subject of numerous research efforts. The efforts indicate a common difficulty in treating the dynamic interaction. This paper presents a semi-analytical technique to solve the bridge/vehicle interaction problem. A skew bridge, idealized as a discretely stiffened thin isotropic plate, is considered. The natural frequencies and mode shapes of the bridge are computed by a pb-2 Rayleigh–Ritz method. The mode superposition principle is then applied. The dynamic response of the bridge to moving vehicle excitation is expressed in terms of mode shapes and normal coordinates. A three-dimensional three-axle vehicle model is developed and consists of 11 independent degrees of freedom. The bridge and the vehicle are treated as two separate systems connected only at the time-varying contact points. An iteration technique is used to deal with the true coupling between the bridge and the vehicle and to satisfy the compatibility of forces and displacements at the contact points. At last, a parametric study is conducted to investigate the dynamic amplification factor. The influences of vehicle type, axle spacing, traffic condition, span length, and skew angle are examined.
AXISYMMETRIC VIBRATION OF CYLINDRICAL SHELLS WITH INTERMEDIATE RING SUPPORTS
Authors: XIANG Y. , LIM C. W. , KITIPORNCHAI S.
Published: April 2003

This paper treats the axisymmetric vibration of thin circular cylindrical shells with intermediate ring supports based on the Goldenveizer–Novozhilov thin shell theory. An analytical method is proposed, and new exact solutions are presented to study the axisymmetric vibration characteristics of the ring supported cylindrical shells. In the proposed method, the state-space technique is employed to derive a homogenous differential equation system for a shell segment, and a domain decomposition approach is developed to cater for the continuity requirements between shell segments. Exact frequency parameters are presented for circular cylindrical shells that have multiple intermediate ring supports and various combinations of end support conditions. These exact vibration frequencies may serve as important benchmarks against which researchers can validate their numerical methods for such circular cylindrical shell problems.
ACTIVE VIBRATION CONTROL OF AN AIRCRAFT CABIN PANEL USING PIEZOELECTRIC SENSORS AND ACTUATORS
Authors: LEE Y. Y. , LAM K. C. , YUEN K. K. , LAM H. F. , YAO J.
Published: April 2003

In this paper, the active vibration suppression of an aircraft cabin panel embedded with piezoelectric sensors and actuators under sinusoidal or random excitation is studied experimentally. The Independent Modal Space Control (IMSC) approach is employed in the controller design. The piezoelectric sensors and actuators associated with the IMSC technique have been applied to the active vibration control of the aircraft panel, and shown to be effective in vibration control. A second order controller is selected in the control scheme to suppress the fundamental modal vibration response of the aircraft cabin panel. The mode shapes of the panel are experimentally obtained, and used as the parameters of the objective functions for minimizing the unwanted vibration responses by appropriately selecting the sensor and actuator gains. Based on the experimental results, it is found that the vibration levels of the open and closed loop systems differ by up to 5.0 dB (for sinusoidal excitation) and 7.4 dB (for random excitation), even when the control circuit is interfered by electrical and magnetic noises.
DEMODULATION BY COMPLEX-VALUED WAVELETS FOR STOCHASTIC PATTERN RECOGNITION
Authors: DAUGMAN JOHN
Published: April 2003

Samples from stochastic signals having sufficient complexity need reveal only a little unexpected shared structure, in order to reject the hypothesis that they are independent. The mere failure of a test of statistical independence can thereby serve as a basis for recognizing stochastic patterns, provided they possess enough degrees-of-freedom, because all unrelated ones would pass such a test. This paper discusses exploitation of this statistical principle, combined with wavelet image coding methods to extract phase descriptions of incoherent patterns. Demodulation and coarse quantization of the phase information creates decision environments characterized by well-separated clusters, and this lends itself to rapid and reliable pattern recognition.
TIME SCALE APPROACH FOR CHIRP DETECTION
Authors: MORVIDONE MARCELA , TORRESANI BRUNO
Published: April 2003

Two different approaches for joint detection and estimation of signals embedded in stationary random noise are considered and compared, for the subclass of amplitude and frequency modulated signals. Matched filter approaches are compared to time-frequency and time scale based approaches. Particular attention is paid to the case of the so-called "power-law chirps", characterized by monomial and polynomial amplitude and frequency functions. As target application, the problem of gravitational waves at interferometric detectors is considered.
ON PRECONDITIONING MULTIWAVELET SYSTEMS FOR IMAGE COMPRESSION
Authors: KIM WONKOO , LI CHING-CHUNG
Published: April 2003

This paper presents a study on applications of multiwavelet analysis to image compression. The biorthogonality and perfect reconstruction conditions are applied to multiwavelet filters. As a multiwavelet filter bank has multiple channels of inputs, the data structure of inputs to the multiwavelet system should be taken into consideration in multiwavelet decomposition and reconstruction algorithms. We investigate the data initialization problem by considering prefilters and postfilters that may give more efficient representations of the decomposed data. The interpolation postfilter and prefilter are formulated, which are capable to provide a better approximate image at each coarser resolution level. A design process is given to obtain both filters having compact supports, if exist. Image compression performances of three multiwavelet systems are studied in comparison to those of single wavelet systems.
STABILITY OF BIORTHOGONAL WAVELET BASES
Authors: CURRAN PAUL F. , McDARBY GARY
Published: April 2003

We investigate the lifting scheme as a method for constructing compactly supported biorthogonal scaling functions and wavelets. A well-known issue arising with the use of this scheme is that the resulting functions are only formally biorthogonal. It is not guaranteed that the new wavelet bases actually exist in an acceptable sense. To verify that these bases do exist one must test an associated linear operator to ensure that it has a simple eigenvalue at one and that all its remaining eigenvalues have modulus less than one, a task which becomes numerically intensive if undertaken repeatedly. We simplify this verification procedure in two ways: (i) we show that one need only test an identifiable half of the eigenvalues of the operator, (ii) we show that when the operator depends upon a single parameter, the test first fails for values of that parameter at which the eigenvalue at one becomes a multiple eigenvalue. We propose that this new verification procedure comprises a first step towards determining simple conditions, supplementary to the lifting scheme, to ensure existence of the new wavelets generated by the scheme and develop an algorithm to this effect.
M-BAND WAVELETS: APPLICATION TO TEXTURE SEGMENTATION FOR REAL LIFE IMAGE ANALYSIS
Authors: KUNDU MALAY K. , ACHARYYA MAUSUMI
Published: April 2003

This paper describes two examples of real-life applications of texture segmentation using M-band wavelets. In the first part of the paper, an efficient and computationally fast method for segmenting text and graphics part of a document image based on textural cues is presented. It is logical to assume that the graphics part has different textural properties than the non-graphics (text) part. So, this is basically a two-class texture segmentation problem. The second part of the paper describes a segmentation scheme for another real-life data such as remotely sensed image. Different quasi-homogeneous regions in the image can be treated to have different texture properties. Based on this assumption the multi-class texture segmentation scheme is applied for this purpose.