optimal design of constrained fir filters without phase response specifications finite impulse response fir filters without phase response specifications have found many applications in signal processing and communications it is shown in this paper that the constrained lp magnitude error design of such an fir filter is equivalent to a constrained lp approximation of a given response with a phase equal to that of the optimal filter of the original problem an iterative method is then proposed to compute that phase by converting the nonconvex constrained lp magnitude error problem into a series of convex constrained lp elliptic frequency response error subproblems it is also shown that the solutions of these convex subproblems converge to a karush kuhn tucker point of the original problem the convergence and its model parameter and initial condition dependence are shown through the designs of fir filters without time domain constraints the iterative method is then applied to the minimax design of evidence filters nyquist filters and step response constrained filters and to the lp design of pulse shaping filters for ultra wideband systems design examples demonstrate that the proposed method obtains better filters in terms of magnitude error group delay and spectrum utilization efficiency than existing methods

permutable products of supersoluble groups we investigate the structure of finite groups that are the mutually permutable product of two supersoluble groups we show that the supersoluble residual is nilpotent and the fitting quotient group is metabelian these results are consequences of our main theorem which states that such a product is supersoluble when the intersection of the two factors is core free in the group

on σ subnormal and σ permutable subgroups of finite groups let i i i be some partition of the set p of all primes that is p i i i and i j for all i j let g be a finite group we say that g is primary if g is a i group for some i i soluble if every chief factor of g is primary we say that a set h h1 ht of hall subgroups of g where hi is primary i 1 t is a complete hall set of type of g if hi hj 1 for all i j and g h1 ht we say that a subgroup a of g is subnormal in g if there is a subgroup chain a a0 a1 an g such that either ai 1 is normal in ai or ai ai 1 ai is primary for all i 1 t permutable in g if g has a complete hall set h of type such that a is hg permutable in g that is ahx hxa for all x g and all h h we study the relationship between the subnormal and permutable subgroups of g in particular we prove that every permutable subgroup of g is subnormal and we classify finite soluble groups in which every subnormal subgroup is permutable

pseudo qmf banks with near equiripple performance a novel method using the parks mcclellan equiripple design procedure obtains a linear phase spectral factor of an equiripple approximate 2mth band lowpass filter this filter which is an equiripple prototype of an m channel pseudo qmf bank is modified to make it a closer approximation of a linear phase spectral factor of a 2mth band filter reducing the maximum overall reconstruction error to the order of the stopband ripple while slightly compromising equiripple performance

quasilinear hyperbolic parabolic equations of one dimensional viscoelasticity abstract we study the global existence of solutions of initial boundary value problems for a quasilinear hyperbolic parabolic equation describing the longitudinal motion of a one dimensional viscoelastic rod we treat a variety of nonhomogeneous boundary conditions requiring separate analyses because they lead to distinctive physical effects we employ a constitutive equation giving the stress as a general nonlinear function of the strain and the strain rate all global analyses of this and related problems except that of dafermos j differential equations 1969 71 86 have employed a stress that is merely affine in the strain rate dafermos s assumptions are far more appropriate for shearing motions than for longitudinal motions our constitutive equation satisfies the physically natural requirement that an infinite amount of compressive stress is needed to produce a total compression at any point of the rod this requirement is the source of a severe singularity in the governing partial differential equations which is particularly acute when time dependent dirichlet data are prescribed the further novel yet physically reasonable restrictions we impose on the constitutive function yield estimates that preclude a total compression anywhere at any finite time the resulting estimates are crucial for the global existence theory we obtain

some new characterizations of pst groups abstract let h and b be subgroups of a finite group g such that g n g h b then we say that h is quasipermutable respectively s quasipermutable in g provided h permutes with b and with every subgroup respectively with every sylow subgroup a of b such that h a 1 in this paper we analyze the influence of s quasipermutable and quasipermutable subgroups on the structure of g as an application we give new characterizations of soluble pst groups

interpolated lir mth band filter design with allpass subfilters we propose a new allpass based structure for the iir mth and 2mth band filters these filters consist of m allpass filters and an interpolation filter sum of two allpasses consequently the proposed structure is very efficient in implementation by choosing the allpass phase appropriately the resulting phase response of the iir mth band filter becomes approximately linear an example is designed and compared with fir mth band filters

finite groups with subgroups supersoluble or subnormal abstract the aim of this paper is to study the structure of finite groups whose non subnormal subgroups lie in some subclasses of the class of finite supersoluble groups

totally permutable products of certain classes of finite groups abstract subgroups a and b of a finite group are said to be totally permutable if every subgroup of a permutes with every subgroup of b the behaviour of finite pairwise totally permutable products are studied with respect to certain classes of groups including the class of groups where all the subnormal subgroups permute with all the maximal subgroups the so called sm groups and also the class of groups where all the subnormal subgroups are permutable the so called pt groups

derivative controlled design of linear phase fir filters via waveform moments a new method for designing linear phase finite impulse response fir filters is proposed by using the blockwise waveform moments the proposed method yields linear phase fir filters whose magnitude response and its derivatives to a certain order take the prescribed values at equally spaced frequency points the design procedure only needs to solve a system of linear equations whose size is slightly smaller than the degree of the resulting filter in addition the inversion of the linear equations can be essentially precomputed therefore the proposed design method is computationally efficient in particular for some important cases i e the maximally flat r regular l sup th band fir filters a closed form formula can be obtained it is also shown that the resulting r regular l sup th band fir filters have the zero intersymbol interference property

radially symmetric motions of nonlinearly viscoelastic bodies under live loads this paper treats radially symmetric motions of nonlinearly viscoelastic circular cylindrical and spherical shells subjected to the live loads of centrifugal force and time dependent hydrostatic pressures the governing equations are exact versions of those for 3 dimensional continuum mechanics so shell does not connote an approximate via some shell theory these motions are governed by quasilinear third order parabolic hyperbolic equations having but one independent spatial variable the principal part of such a partial differential equation is determined by a general family of nonlinear constitutive equations the presence of strains in two orthogonal directions requires a careful treatment of constitutive restrictions that are physically natural and support the analysis the interaction of geometrically exact formulations the compatible use of general constitutive equations for material response and the presence of live loads show how these factors play crucial roles in the behavior of solutions in particular for different kinds of live loads there are thresholds separating materials that produce qualitatively different dynamical behavior the analysis using classical methods covers infinite time blowup for cylindrical shells subject to centrifugal forces infinite time blowup for cylindrical shells subject to steady and time dependent hydrostatic pressures finite time blowup for spherical shells subject to steady and time dependent hydrostatic pressures and the preclusion of total compression this paper concludes with a sketch using some modern methods of the existence of regular solutions until the time of blowup

theory of regular m band wavelet bases orthonormal m band wavelet bases have been constructed and applied by several authors this paper makes three main contributions first it generalizes the minimal length k regular 2 band wavelets of daubechies 1988 to the m band case by deriving explicit formulas for k regular m band scaling filters several equivalent characterizations of k regularity are given and their significance explained second two approaches to the construction of the m 1 wavelet filters and associated wavelet bases are described one relies on a state space characterization with a novel technique to obtain the unitary wavelet filters the other uses a factorization approach third this paper gives a set of necessary and sufficient condition on the m band scaling filter for it to generate an orthonormal wavelet basis the conditions are very similar to those obtained by cohen 1990 and lawton 1990 for 2 band wavelets

hall subgroups and π separable groups abstract let g be a finite group and a set of primes in this paper some new criteria for separable groups and solvable groups in terms of hall subgroups are proved the main results are the following theorem g is a separable group if and only if 1 g satisfies e and e 2 g satisfies e q and e p for all p q theorem g is a separable group if and only if 1 g satisfies e and e 2 g satisfies e p q for all p and q

maxflat fractional delay iir filter design fractional delay fd filters are an important class of digital filters and are useful in various signal processing applications this paper discusses a design problem of fd infinite impulse response iir filters with the maxflat frequency response in frequency domain first a flatness condition of fd filters at an arbitrarily specified frequency point is described and then a system of linear equations is derived from the flatness condition therefore a set of filter coefficients can be easily obtained by solving this system of linear equations for a special case in which the frequency response is required to be maxflat at omega 0 or pi a closed form expression for its filter coefficients is derived by solving a linear system of vandermonde equations it is also shown that the existing maxflat fd finite impulse response fir and iir filters are special cases of the fd iir filters proposed in this paper finally some examples are presented to demonstrate the effectiveness of the proposed filters

on some classes of supersoluble groups finite groups g for which for every subgroup h and for all primes q dividing the index g h there exists a subgroup k of g such that h is contained in k and k h q are called y groups groups in which subnormal subgroups permute with all sylow subgroups are called pst groups in this paper a local version of the y property leading to a local characterisation of y groups from which the classical characterisation emerges is introduced the relationship between pst groups and y groups is also analysed

linear matrix inequality formulation of spectral mask constraints with applications to fir filter design the design of a finite impulse response fir filter often involves a spectral mask that the magnitude spectrum must satisfy the mask specifies upper and lower bounds at each frequency and hence yields an infinite number of constraints in current practice spectral masks are often approximated by discretization but in this paper we derive a result that allows us to precisely enforce piecewise constant and piecewise trigonometric polynomial masks in a finite and convex manner via linear matrix inequalities while this result is theoretically satisfying in that it allows us to avoid the heuristic approximations involved in discretization techniques it is also of practical interest because it generates competitive design algorithms based on interior point methods for a diverse class of fir filtering and narrowband beamforming problems the examples we provide include the design of standard linear and nonlinear phase fir filters robust chip waveforms for wireless communications and narrowband beamformers for linear antenna arrays our main result also provides a contribution to system theory as it is an extension of the well known positive real and bounded real lemmas

near perfect reconstruction pseudo qmf banks a novel approach to the design of m channel pseudo quadrature mirror filter qmf banks is presented in this approach the prototype filter is constrained to be a linear phase spectral factor of a 2mth band filter as a result the overall transfer function of the analysis synthesis system is a delay moreover the aliasing cancellation ac constraint is derived such that all the significant aliasing terms are canceled consequently the aliasing level at the output is comparable to the stopband attenuation of the prototype filter in other words the only error at the output of the analysis synthesis system is the aliasing error which is at the level of stopband attenuation using this approach it is possible to design a pseudo qmf bank where the stopband attenuation of the analysis and thus synthesis filters is on the order of spl minus 100 db moreover the resulting reconstruction error is also on the order of spl minus 100 db several examples are included

sylow permutable subnormal subgroups of finite groups abstract an extension of the well known frobenius criterion of p nilpotence in groups with modular sylow p subgroups is proved in the paper this result is useful to get information about the classes of groups in which every subnormal subgroup is permutable and sylow permutable

on σ supersoluble groups and one generalization of clt groups abstract let g be a finite group and i i i be a partition of the set of all primes p a chief factor h k of g is said to be central in g if the semidirect product h k g c g h k is a i group for some i i the group g is said to be nilpotent if either g 1 or every chief factor of g is central let g n be the nilpotent residual of g that is the intersection of all normal subgroups n of g with nilpotent quotient g n then we say that g is supersoluble if each chief factor of g below g n is cyclic in this paper we study properties of supersoluble groups and also consider some applications of such groups in the theory of generalized clt groups

criteria for permutability to be transitive in finite groups abstract a group g is a pt group if for subgroups h and k with h permutable in k and k permutable in g it is always the case that h is permutable in g it is shown that a finite group is a soluble pt group if and only if each subgroup of a sylow subgroup is permutable in the sylow normalizer

self sustained oscillations of nonlinearly viscoelastic layers we study the motion of an incompressible nonlinearly viscoelastic layer subject to a slip stick frictional force applied to one of its faces by a moving belt this system is governed by a third order quasi linear parabolic hyperbolic partial differential equation subject to complicated boundary conditions we use a refined version of the hopf bifurcation theorem to show that this problem admits periodic solutions for the belt speed near critical values with the number of such solutions increasing as the viscosity of the layer decreases to verify the hypotheses of this theorem we must devote considerable effort to the tricky analysis of how the spectrum of the linearized problem depends on the belt speed and material parameters our analysis is complemented with both computations and a proof of the topological fact that the computed disposition of the eigenvalues does not omit any others we complete our study with a perturbation analysis justified by the hopf bifurcation theorem

on hall subnormally embedded and generalized nilpotent groups abstract a subgroup h of a finite group g is said to be hall subnormally embedded in g if h is a hall subgroup of the subnormal closure h s g in this paper some new characterizations for finite groups are obtained based on the assumption that some subgroups are hall subnormally embedded

groups with chernikov conjugacy classes in which sylow permutability is a transitive relation a subgroup h of a periodic group g is said to be sylow permutable in g if hs sh for every sylow subgroup s of g like normality sylow permutability is not a transitive relation in this paper we characterize periodic locally soluble groups with chernikov conjugacy classes periodic locally soluble cc groups in which sylow permutability is a transitive relation pst groups describing their structure in a very detailed way then extending the structure of finite soluble pst groups moreover we give an effective construction of these groups

on totally permutable products of finite groups this paper has been published in journal of algebra 293 1 269 278 2005 copyright 2005 by elsevier http dx doi org 10 1016 j jalgebra 2005 01 033

moment of cepstrum and its applications it is shown that the moments of a signal sequence and of its corresponding cepstral sequence are related in a way which obviates the need for the direct calculation of the cepstral coefficients hence an ideal calculation for the moments of the cepstrum is possible even if the duration of the cepstrum is infinite it is also possible to describe all the properties of a signal sequence from its moments the effectiveness of this method is demonstrated in the problems of homomorphic deconvolution and echo removal it is also shown that in linear filtering problems the moments of the minimum phase sequence are calculated from the corresponding linear phase sequence without actually calculating the minimum phase sequence for a discrete time real signal sequence with finite duration complete equivalence is demonstrated between the signal sequence and its moments this permits a new description and a new set of design specifications based on moments for such systems

clt groups with normal or abnormal subgroups abstract finite groups g for every divisor d of the order of g if there exists a subgroup h of g of order d such that h is normal or abnormal are called c groups in this paper c groups are characterized as certain extensions of nilpotent normal subgroups by subgroups of prime power order

a method for design of mth band filters the objective of this paper is to present a theory constraints and a design method for nonlinear phase halfband and mth band filters based on a time domain property the constraints and properties in the frequency domain are derived they are the generalization of the well known conditions for linear phase mth band filters having found all necessary conditions we present the design method based on an eigenfilter that minimizes the mean squared errors the design method is also extended to the design of nonlinear phase mth band filters with properties of r regularity or equiripple stopband attenuation or impulse responses that have complex coefficients design examples of various mth band filters with different properties are presented discussed and compared with the linear phase case

the parabolic hyperbolic system governing the spatial motion of nonlinearly viscoelastic rods this paper treats initial boundary value problems governing the motion in space of nonlinearly viscoelastic rods of strain rate type it introduces and exploits a set of physically natural constitutive hypotheses to prove that solutions exist for all time and depend continuously on the data the equations are those for a very general properly invariant theory of rods that can suffer flexure torsion extension and shear in this theory the contact forces and couples depend on strains measuring these effects and on the time derivatives of these strains

on σ local fitting classes abstract let be a partition of the set of all primes p if g is a finite group and f is a fitting class of finite groups the symbol g denotes the set i i g and f f g we call any function f of the form f fitting classes a hartley function or simply h function and we put l r f g g 1 or g 1 and g g i g i f i for all i g if there is an h function f such that f l r f then we say that f is local and f is a local definition of f in this paper we describe some properties of local fitting classes and prove that 1 every local fitting class can be defined by a unique h function f such that f i f i g i f and f i is a lockett class for all i f 2 the product of two local fitting classes is also a local fitting class moreover we also discuss the n multiply local fitting classes

global attractors for degenerate partial differential equations from nonlinear viscoelasticity abstract we study several problems for the forced motion of light uniform nonlinearly viscoelastic bodies carrying heavy attachments a reduced problem for such motions is obtained by setting the ratio of the inertia of the viscoelastic body to the inertia of the attachment equal to zero using methods from infinite dimensional dynamical systems theory we prove that the degenerate partial differential equation of this reduced problem has an attractor and that this attractor is contained in an invariant two dimensional manifold on which solutions are governed by the classical ordinary differential equation for the forced motion of a particle on a massless spring

group classes and mutually permutable products abstract let g a b be the mutually permutable product of the nontrivial subgroups a and b of the group g then a or b contains a nontrivial normal subgroup of g it is also established that s g a s a where s u is the solvable radical of u these facts lead to some generalized results about mutually permutable products of sc groups it is also shown that if g is a pts group then a and b are pst groups

an iteration scheme for the design of equiripple mth band fir filters a new iterative procedure for the design of approximate equiripple mth band fir filters is presented if the deviation from the nyquist condition in the initial filter obtained using standard methods is small enough then the error is reduced in the resultant filter without significant change in the equiripple stop band attenuation

global attractors for quasilinear parabolic hyperbolic equations governing longitudinal motions of nonlinearly viscoelastic rods abstract we prove the existence of a global attractor and estimate its dimension for a general family of third order quasilinear parabolic hyperbolic equations governing the longitudinal motion of nonlinearly viscoelastic rods carrying an end mass and subject to interesting body forces the simplest version of the equations has the form w t t n w x w x t x where n is defined on 0 r and is a strictly increasing function of each of its arguments with n as its first argument goes to 0 this limit characterizes a total compression a source of technical difficulty which new delicate a priori estimates prevent we determine how the dimension of the attractor varies with the ratio of the mass of the rod to that of the end mass giving conditions ensuring that the dimension is small the estimates of dimension illuminate asymptotic analyses of the governing equation as this mass ratio goes to 0

some characterizations of finite σ soluble pσt groups abstract let i i i be some partition of the set of all primes p and g a finite group g is said to be soluble if every chief factor h k of g is a i group for some i i h k a set h of subgroups of g is said to be a complete hall set of g if every member 1 of h is a hall i subgroup of g for some i and h contains exactly one hall i subgroup of g for every i i such that i g a subgroup a of g is said to be permutable in g if g has a complete hall set h such that a h x h x a for all x g and all h h we obtain characterizations of finite soluble groups g in which permutability is a transitive relation in g

snakes oriented families of periodic orbits their sources sinks and continuation abstract poincare observed that for a differential equation x x depending on a parameter each periodic orbit generally lies in a connected family of orbits in x space in order to investigate certain large connected sets denoted q of orbits containing a given orbit we introduce two indices an orbit index and a center index defined at certain stationary points we show that genetically there are two types of hopf bifurcation those we call sources 1 and sinks 1 generically if the set q is bounded in x space and if there is an upper bound for periods of the orbits in q then q must have as many source hopf bifurcations as sink hopf bifurcations and each source is connected to a sink by an oriented one parameter snake of orbits a snake is a maximal path of orbits that contains no orbits whose orbit index is 0 see fig 1 1

solvable pst groups strong sylow bases and mutually permutable products article history as ubgrouph of a group g is said to permute with the subgroup k of g if hk kh s ubgroupsh and k are mutually permutable totally permutable i ng if every subgroup of h permutes with k and every subgroup of k permutes with h if every subgroup

biorthogonal coiflets coiflets are filter banks where the sum of the number of vanishing moments of the analysis and synthesis limit functions is maximum for a given support width it is known how to design biorthogonal coiflets with odd length filters however the precise relationship among the vanishing moments of the analysis and synthesis scaling functions is unknown this is the first problem solved in this correspondence second biorthogonal coiflets with even length filters which have remained unknown previously are designed and the relationship among the vanishing moments of the analysis and synthesis limit functions shown a generalization of the bernstein polynomial is advanced each of these two wavelet families is parametrized by three integers the design is based on explicit formulae

dynamics as a mechanism preventing the formation of finer and finer microstructure we study the dynamics of pattern formation in the one dimensional partial differential equation u u w u x x u xxt u 0 text u u x t text x in 0 1 text t 0 proposed recently by ball holmes james pego swart bhjps as a mathematical cartoon for the dynamic formation of microstructures observed in various crystalline solids here w is a double well potential like 1 4 ux 2 1 2 what makes this equation interesting and unusual is that it possesses as a lyapunov function a free energy consisting of kinetic energy plus a nonconvex elastic energy but no interfacial energy contribution which does not attain a minimum but favours the formation of finer and finer phase mixtures e u u t int limits 0 1 frac u t 2 2 w u x frac u 2 2 dx our analysis of the dynamics confirms the following surprising and striking difference between statics and dynamics conjectured in bhjps on the basis of numerical simulations of swart holmes sh while minimizing the above energy predicts infinitely fine patterns mathematically weak but not strong convergence of all minimizing sequences unvn of e u v in the sobolev space w1p 0 1 l2 0 1 solutions to the evolution equation of ball et al typically develop patterns of small but finite length scale mathematically strong convergence in w1p 0 1 l2 0 1 of all solutions u t ut t with low initial energy as time t

subgroups permutable with all sylow subgroups fix a finite group g whenever s is a nonempty set of subgroups of g let sh denote the set of all subgroups h of g permutable with all s g s h so that the complex product hs s sh is their join it is obvious that s is closed with respect to joins in case s s syl g is the set of all sylow subgroups of g for all primes it is also closed with respect to intersec w x h tions kegel 4 so that syl g is a lattice the present paper may be seen as continuation of kegel s work to be more precise it aims to continue the first part of his work the second one being completed by w x kleidman 5 h syl g is the full subgroup lattice of g precisely when g g n is nilpotent the formation n of nilpotent groups will play a central role in general as usual we denote by g the nilpotent residual of g for subgroups h and k of g we write h s f h x and h k s k x g k 2 x x h x g k for the k core and the k closure of h respectively h s y1 x hx h k h suppose h g syl g then h and h do belong to syl g for all k n k but h usually does not nor does it the commutator group h9 nor the centre z h on the other hand we know that there is a unique subgroup of h minimal subject to containing h n and belonging to h syl g this is always a normal subgroup of g

constraints on the cutoff frequencies of mth band linear phase fir filters constraints are derived for the cutoff frequencies of linear phase fir mth band filters such that the filters have good passband and stopband characteristics i e ones that very closely approximate an ordinary non mth band filter designed using some optimal method constraints on lowpass filters are first considered and the results are extended to multiband filters

closed form design of generalized maxflat r regular fir m th band filters using waveform moments mth band filters have found numerous applications in multirate signal processing systems filter banks and wavelets in this paper the design problem of generalized maxflat r regular finite impulse response fir mth band filters with a specified integer group delay at omega 0 is considered and the closed form expression for its impulse response is presented the filter coefficients are directly derived by solving a linear system of vandermonde equations that are obtained from the regularity condition of the maxflat r regular fir mth band filters via the blockwise waveform moments differing from the conventional fir mth band filters with exactly linear phase responses the generalized fir mth band filters proposed in this paper have an arbitrarily specified integer group delay at omega 0 moreover a new efficient implementation of the generalized maxflat r regular fir mth band filters is proposed by making use of the relationship between the filter coefficients in the closed form solution finally several design examples are presented to demonstrate the effectiveness of the proposed fir mth band filters

on mutually permutable products of finite groups abstract in this paper a structural theorem about mutually permutable products of finite groups is obtained this result is used to derive some results on mutually permutable products of groups whose chief factors are simple some earlier results on mutually permutable products of supersoluble groups appear as particular cases

quasilinear equations for viscoelasticity of strain rate type we consider the quasilinear m m system of partial differential equations that governs the motion of a viscoelastic material of strain rate type on a bounded domain in mathbb r n the dependence of the stress on both the strain and strain rate is nonlinear and our hypotheses allow for a potential energy which is a nonconvex function of the strain the critical hypothesis is that the dependence of the stress function on the strain rate is uniformly strictly monotone in the sense of minty and browder we prove the existence and uniqueness of weak solutions to a natural initial boundary value problem for a large class of constitutive functions we then treat the question of h2 regularity of solutions and show that while regularity in the initial data is preserved solutions do not in general become more regular than their initial data this generalizes a result for the semilinear case due to rybka

weak solutions for a class of nonlinear systems of viscoelasticity the principal focus of the article is the construction of classical weak solutions of the initial value problem for a class of systems of viscoelasticity in arbitrary spatial dimension the class of systems studied is large enough to incorporate certain requirements dictated by frame indifference and also has a structure which allows for a variational treatment of the time discretized problem weak solutions for this system are constructed under certain monotonicity hypotheses and are shown to satisfy various a priori estimates in particular giving improved regularity for the time derivative also measure valued solutions are obtained under a uniform dissipation condition which is much weaker than monotonicity a special case of the viscoelastic system is the gradient flow of a non convex potential for which measure valued solutions are here obtained a new result in the vectorial case furthermore in this setting it is possible to show that these measure valued solutions satisfy a certain property which ensures they coincide with the classical weak solution when this exists as for example in the convex case where existence and uniqueness are well known

on the modeling and computations of nonlinear thermodynamics in sma wires we present a mathematical model describing the thermodynamic behavior of shape memory alloy wires as well as a computational technique to solve the resulting system of partial differential equations the model consists of continuum level conservation equations based on a new construction of the helmholtz free energy potential this construction allows specification of material constants for different shape memory wires the computational technique introduces a viscosity based continuation method which allows the model to handle dynamic applications where the temporally local behavior of solutions is desired computational experiments document that this combination of modeling and solution techniques appropriately predicts the thermally and stress induced martensitic phase transitions as well as the hysteretic behavior and production of latent heat associated with such materials

extensions with overlap abstract let n be a normal subgroup of the group g by a result of p hall g is nilpotent if n and g n are nilpotent we are looking for group classes c and characteristic subgroups f n of n such that the statement above with belongs to c f n substituted for is nilpotent n remains true

generalized kyp lemma unified frequency domain inequalities with design applications the celebrated kalman yakubovic spl caron popov kyp lemma establishes the equivalence between a frequency domain inequality fdi and a linear matrix inequality and has played one of the most fundamental roles in systems and control theory this paper first develops a necessary and sufficient condition for an s procedure to be lossless and uses the result to generalize the kyp lemma in two aspects the frequency range and the class of systems and to unify various existing versions by a single theorem in particular our result covers fdis in finite frequency intervals for both continuous discrete time settings as opposed to the standard infinite frequency range the class of systems for which fdis are considered is no longer constrained to be proper and nonproper transfer functions including polynomials can also be treated we study implications of this generalization and develop a proper interface between the basic result and various engineering applications specifically it is shown that our result allows us to solve a certain class of system design problems with multiple specifications on the gain phase properties in several frequency ranges the method is illustrated by numerical design examples of digital filters and proportional integral derivative controllers

design of fir nyquist filters with low group delay a new method is proposed for designing fir nyquist filters with zero crossing impulse response and low group delay it is first shown that fir nyquist filters that satisfy the zero crossing time domain condition have a frequency response property where both the magnitude and phase responses in the passband are dependent on the stopband response therefore the design problem will become a magnitude approximation in the stopband the proposed procedure is based on the formulation of a linear problem by using the multiple remez exchange algorithm in the stopband directly hence the filter coefficients can be computed by solving linear equations and the optimal solution with an equiripple stopband response is easily obtained after applying an iteration procedure although the proposed nyquist filters have an approximate linear phase response its group delay is lower than the conventional fir nyquist filters the proposed procedure is computationally efficient because it only solves a set of linear equations finally the characteristics of the low delay fir nyquist filters are examined and the performance is compared with the conventional fir nyquist filters

finite soluble groups with permutable subnormal subgroups abstract a finite group g is said to be a pst group if every subnormal subgroup of g permutes with every sylow subgroup of g we shall discuss the normal structure of soluble pst groups mainly defining a local version of this concept a deep study of the local structure turns out to be crucial for obtaining information about the global property moreover a new approach to soluble pt groups i e soluble groups in which permutability is a transitive relation follows naturally from our vision of pst groups our techniques and results provide a unified point of view for t groups pt groups and pst groups in the soluble universe showing that the difference between these classes is quite simply their sylow structure

design and hybrid realization of fir nyquist filters with quantized coefficients and low sensitivity to timing jitter a design of finite impulse response fir nyquist filters with zero intersymbol interference isi and low sensitivity to timing jitter is presented using an affine scaling linear programming algorithm a near optimum quantized coefficient set can be obtained in a feasible computational time by varying a parameter the design provides a tradeoff between the tail energy of the impulse response in the time domain and the stopband of the magnitude response in the frequency domain we also present a pipelined multiplier free fir filter realization with periodically time varying ptv coefficients based on a hybrid form the realizations exploit the coefficient symmetry to reduce the hardware by about one half by placing most of the shifts followed by addition toward the back end of the structure hardware is reduced due to the shorter wordlength of the adders the proposed structure has a provision to increase the speed by adjusting a design parameter but at the expense of more hardware

some classes of finite groups and mutually permutable products this paper has been published in journal of algebra 319 8 3343 3351 2008 copyright 2008 by elsevier http dx doi org 10 1016 j jalgebra 2007 12 001