Adolfo Maia

The evolutionary sound synthesis method

A mathematical model for interactive sound synthesis based on the application of Genetic Algorithms (GA) is presented. The Evolutionary Sound Synthesis Method (ESSynth) generates sequences of waveform variants by the application of genetic operators on an initial population of waveforms. We describe how the waveforms can be treated as genetic code, the fitness evaluation methodology and how genetic operations such as crossover and mutation are used to produce generations of waveforms. Finally, we discuss the results evaluating the generated sounds.

Magnetic monopoles without string in the Kähler–Clifford algebra bundle: A geometrical interpretation

In substitution for Dirac monopoles with string (and for topological monopoles), ‘‘monopoles without string’’ have recently been introduced on the basis of a generalized potential, the sum of a vector A, and a pseudovector γ5 B potential. By making recourse to the Clifford bundle C(τM,g) [(TxM,g)=R1,3; C(TxM,g)=R1,3], which just allows adding together for each x∈M tensors of different ranks, in a previous paper a Lagrangian and Hamiltonian formalism was constructed for interacting monopoles and charges that can be regarded as satisfactory from various points of view. In the present article, after having ‘‘completed’’ the formalism, a purely geometrical interpretation of it is put forth within the Kahler–Clifford bundle K(τ*M,g) of differential forms, essential ingredients being a generalized curvature and the Hodge decomposition theorem. Thus the way is paved for the extension of our ‘‘monopoles without string’’ to non‐Abelian gauge groups. The analogy with supersymmetric theories is apparent.

The classical problem of the charge and pole motion: a satisfactory formalism by Clifford algebras

Abstract In a previous paper of ours [Phys. Lett. B 173 (1986) 233; B 188 (1987) 511E] we put forth a theoretical approach to magnetic monopoles without a string which is formulated in a Clifford bundle. To “complete” our theory, we show that the Maxwell equations - with magnetic monopoles - do imply the correct couplings of the electric current and magnetic current with the electromagnetic field (and, therefore, imply the Lorentz forces and the correct motion equations). In other words, within our Clifford approach to classical electromagnetism, the motion equations and the couplings are derivable from the field equations, without any further recourse to a variational principle and without any ad hoc postulate. The price to pay for that result seems merely to be a very natural assumption, analogous to a similar one that is quite standard in general relativity.

Creating Soundscapes Using Evolutionary Spatial Control

A new way to control sound spatial dispersion using the ESSynth Method is introduced here. The Interaural Time Difference (ITD) is used as genotype of an evolutionary control of sound spatialization. Sound intensity and the ITD azimuth angle are used to define spatial dispersion and spatial similarity. Experimental results where crossover and mutation rates were used to create spatial sonic trajectories are discussed.

Soundscape design through evolutionary engines

Two implementations of an Evolutionary Sound Synthesis method using the Interaural Time Difference (ITD) and psychoacoustic descriptors are presented here as a way to develop criteria for fitness evaluation. We also explore a relationship between adaptive sound evolution and three soundscape characteristics: keysounds, key-signals and sound-marks. Sonic Localization Field is defined using a sound attenuation factor and ITD azimuth angle, respectively (Ii, Li). These pairs are used to build Spatial Sound Genotypes (SSG) and they are extracted from a waveform population set. An explanation on how our model was initially written in MATLAB is followed by a recent Pure Data (Pd) implementation. It also elucidates the development and use of: parametric scores, a triplet of psychoacoustic descriptors and the correspondent graphical user interface.

Absence of a zero-point ambiguity

Abstract We study in this work the ambiguity between the two definitions of vacuum energy, namely, the energy of the zero-point fields and the minimum of the effective potential. We name their difference the zero-point ambiguity (ZPA) and show that for a self-interacting mass scalar field in the geometry of Casimir plates and in N = m + 1 space-time dimensions the renormalized ZPA vanishes. So, it is undetectable via Casimir forces.

A computer environment for polymodal music

KYKLOS, an algorithmic composition program, is presented here. It generalises musical scales for use in composition as well as in performance. The sonic output of the system is referred to as polymodal music since it consists of four independent voices playing ‘synthetic modes’. KYKLOS is suitable for computer-assisted composition because it generates MIDI files which can be altered later by the composer. It can equally well be used in live performance for dynamic modification of parameters enabling realtime musical control.

A GENERALIZED DIRAC’S QUANTIZATION CONDITION FOR PHENOMENOLOGICAL NON-ABELIAN MAGNETIC MONOPOLES

We extend the Dirac’s quantization condition for the phenomenological non-Abelian magnetic monopoles whose theory was developed in a number of papers in the past few years.

Uma Demonstração de como o Método da Função Zeta para o Potencial Efetivo Elimina as Divergências

The calculation of the minimum of the e ective potential using the zeta function method is extremely advantagous, because the zeta function is regular at s = 0 and we gain immediately a finite result for the effective potential without the necessity of subtratction of any pole or the addition of infinite counter-terms. The purpose of this paper is to explicitly point out how the cancellation of the divergences occurs and that the zeta function method implicitly uses the same procedure used by Bollini-Giambiagi and Salam-Strathdee in order to gain -nite part of functions with a simple pole.The calculation of the minimum of the e ective potential using the zeta function method is extremely advantagous, because the zeta function is regular at s = 0 and we gain immediately a finite result for the effective potential without the necessity of subtratction of any pole or the addition of infinite counter-terms. The purpose of this paper is to explicitly point out how the cancellation of the divergences occurs and that the zeta function method implicitly uses the same procedure used by Bollini-Giambiagi and Salam-Strathdee in order to gain -nite part of functions with a simple pole.

MAGNETIC MONOPOLES WITHOUT STRINGS BY KÄHLER-CLIFFORD ALGEBRA: GEOMETRICAL INTERPRETATION OF A SATISFACTORY FORMALISM

In place of Dirac monopoles with string, we have recently introduced “monopoles without string” on the basis of a generalized potential, the sum of a vector A and a pseudovector γ5B potential. By having recourse to the (graded) Clifford algebra which allows adding together tensors of different ranks (e.g., scalars+pseudoscalars+vectors+pseudovectors+...), in a previous paper we succeeded in constructing a lagrangian and hamiltonian formalism for interacting monopoles that can be regarded as satisfactory from various points of view. In the present note, after having completed that formalism, we put forth a purely geometrical interpretation of it within the Kahler algebra on differential forms, essential ingredients being the natural introduction of a “generalized curvature” and the Hodge decomposition. We thus pave the way for the extension of our “monopoles without string” to non-abelian gauge groups. The analogies of this approach with supersymmetric theories are apparent.