Alexander Melkozerov

Improved design of modal filter for electronics protection

A new structure of modal filter which is more relevant for lightning protection of electronics than previously considered structures is proposed. Decrease of modal filter length or increase of original pulse width by factor of 10 and increase of modal filter attenuation from factor of 2 up to factor of 5 is shown. Condition for equal magnitudes of decomposed pulses and analytic formula for their values against a ratio of even to odd mode characteristic impedances are derived. Dependence of these values on coupling is shown for practical parameters of the new structure based on FR-4. On the basis of the calculated data an experimental prototype of an improved modal filter has been made. An experimental investigation has been performed.

The Dynamics of Self-Adaptive Multirecombinant Evolution Strategies on the General Ellipsoid Model

The optimization behavior of the self-adaptation (SA) evolution strategy (ES) with intermediate multi-recombination [(μ/μ_I, λ)-σSA-ES] using isotropic mutations is investigated on convex-quadratic functions (referred to as ellipsoid model). An asymptotically exact quadratic progress rate formula is derived. This is used to model the dynamical ES system by a set of difference equations. The solutions of this system are used to analytically calculate the optimal learning parameter τ. The theoretical results are compared and validated by comparison with real (μ/μ_I, λ)-σSA-ES runs on two ellipsoid test model cases. The theoretical results clearly indicate that using a model-independent learning parameter τ leads to suboptimal performance of the (μ/μI, λ)-σSA-ES on objective functions with changing local condition numbers as often encountered in practical problems with complex fitness landscapes.

Design of printed modal filters for computer network protection

Preliminary results of simple printed structures (modal filters) design for mitigation of short pulse lightning effects on computer networks are considered. For two types of two-conductor coupled lines on a dielectric substrate the L, C, Z matrixes, per unit length propagation delays and their absolute and relative differences are calculated. These differences are maximized using the parametric optimization of conductor width and separation by genetic algorithms for substrate thickness 0.5 mm and relative permittivity 5. It is demonstrated that differences of per unit length propagation delays for specially designed printed structures may be considerably more than the one for existing flat cables. Proper use of similar structures is proposed for lightning protection.

Noisy optimization: a theoretical strategy comparison of ES, EGS, SPSA & IF on the noisy sphere

This paper presents a performance comparison of 4 direct search strategies in continuous search spaces using the noisy sphere as test function. While the results of the Evolution Strategy (ES), Evolutionary Gradient Search (EGS), Simultaneous Perturbation Stochastic Approximation (SPSA) considered are already known from literature, Implicit Filtering (IF) as the fourth strategy is firstly analyzed in this paper. After a short review of ES, EGS, and SPSA, the derivation of the quality gain formula of IF is sketched. Using the results, a comparison of the strategies is performed that worked out the similarities and differences of the strategies.

Simple and free mitigation of short pulse lightning effects by flat power cables

Three-conductor flat power cables as simple and cost free mitigation of short pulse lightning effects are considered. For six types of commonly available cables their L, C, Z matrixes, per unit length propagation delays and their differences are calculated. It is shown that proper use of inherent properties of similar cables is possible for lightning protection. It is demonstrated that flat cables without air gaps in cross section are more suitable for this aim.

On the analysis of self-adaptive evolution strategies on elliptic model: first results

In this paper, first results on the analysis of self-adaptive evolution strategies (ES) with intermediate multirecombination on the elliptic model are presented. Equations describing the ES behavior on the ellipsoid will be derived using a deterministic approach and experimentally verified. A relationship between newly obtained formulae for the elliptic model and previous theoretical results will be discussed.

On the behaviour of weighted multi-recombination evolution strategies optimising noisy cigar functions

Cigar functions are convex quadratic functions that are characterised by the presence of only two distinct eigenvalues of their Hessian, the smaller one of which occurs with multiplicity one. Their ridge-like topology makes them a useful test case for optimisation strategies. This paper extends previous work on modelling the behaviour of evolution strategies with isotropically distributed mutations optimising cigar functions by considering weighted recombination as well as the effects of noise on optimisation performance. It is found that the same weights that have previously been seen to be optimal for the sphere and parabolic ridge functions are optimal for cigar functions as well. The influence of the presence of noise on optimisation performance depends qualitatively on the trajectory of the search point, which in turn is determined by the strategys mutation strength as well as its population size and recombination weights. Analytical results are obtained for the case of cumulative step length adaptation.

σ-Self-Adaptive Weighted Multirecombination Evolution Strategy with Scaled Weights on the Noisy Sphere

This paper presents a performance analysis of the recentlyproposed σ-self-adaptive weighted recombinationevolution strategy (ES) with scaled weights. The steady statebehavior of this ES is investigated for the non-noisy and noisycase, and formulas for the optimal choice of the learning parameterare derived allowing the strategy to reach maximal performance. Acomparison between weighted multirecombination ES withσ-self-adaptation (σSA) and withcumulative step size adaptation (CSA) shows that the self-adaptiveES is able to reach similar (or even better) performance as its CSAcounterpart on the noisy sphere.

Mutative σ-self-adaptation can beat cumulative step size adaptation when using weighted recombination

This paper proposes the σ-self-adaptive weighted multirecombination evolution strategy (ES) and presents a performance analysis of this newly engineered ES. The steady state behavior of this strategy is investigated on the sphere model and a formula for the optimal choice of the learning parameter is derived allowing the ES to reach maximal performance. A comparison between weighted multirecombination ES with σ-self-adaptation (σSA) and with cumulative step size adaptation (CSA) shows that the σ-self-adaptive ES can exhibit the same performance and can even outperform its CSA counterpart for a range of learning parameters.

Towards an Analysis of Self-Adaptive Evolution Strategies on the Noisy Ellipsoid Model

This paper analyzes the multi-recombinant self-adaptive evolution strategy (ES), denoted as(μ/μI, λ)-σSA-ES on the convex-quadratic function class under the influence of noise, which is referred to as noisy ellipsoid model. Asymptotically exact progress rate and self-adaptation response measures are derived (i.e., for N → ∞, N - search space dimensionality) for the considered objective function model and verified using experimental ES runs.