Computer Simulation of Musical Evolution: A Lesson from Whales

Simulating musical creativity using computers needs more than the ability to devise elegant computational implementations of sophisticated algorithms. It requires, firstly, an understanding of what phenomena might be regarded as music; and, secondly, an understanding of the nature of such phenomena — including their evolutionary history, their recursive-hierarchic structure, and the mechanisms by which they are transmitted within cultural groups. To understand these issues it is fruitful to compare human music, and indeed human language, with analogous phenomena in other areas of the animal kingdom. Whale song, specifically that of the humpback (Megaptera novaeangeliae), possesses many structural and functional similarities to human music (as do certain types of birdsong). Using a memetic perspective, this paper compares the “musilanguage” of humpbacks with the music of humans, and aims to identify a number of shared characteristics. A consequence of nature and nurture, these commonalities appear to arise partly from certain constraints of perception and cognition (and thus they determine an aspect of the environment within which the “musemes” (musical memes) constituting whale vocalizations and human music is replicated), and partly from the social-emotive-embodied and sexual-selective nature of musemic transmission. The paper argues that Universal-Darwinian forces give rise to uniformities of structure in phenomena we might regard as “music”, irrespective of the animal group — certain primates, cetaceans or birds - within which it occurs. It considers the extent to which whale song might be regarded as creative, by invoking certain criteria used to assess this attribute in human music. On the basis of these various comparisons, the paper concludes by attempting to draw conclusions applicable to those engaged in designing evolutionary music simulation/generation algorithms

Some results on Denault's capital allocation rule.

Denault (2001) introduces a capital allocation principle where the capital allocated to any risk unit is expressed in terms of the contribution of that risk to the aggregate conditional tail expectation. Panjer (2002) derives a closed-form expression for this allocation rule in the multivariate normal case. Landsman & Valdez (2003) generalize Panjer's result to the class of multivariate elliptical distributions. In this paper we provide an alternative and much simpler proof for the allocation formula in the elliptical case. Further, we show how to derive accurate closed-form approximations for Denault's allocation formula in case of lognormal risks.Capital allocation;

Flying-capacitor multilevel converter voltage balance dynamics for pure resistive load

Multilevel converters need voltage balancing to be able to generate an output voltage with high quality. Flying capacitor converter topology has a natural voltage balancing property. Voltage balance dynamics analytical research methods reported to date are essentially based on a frequency domain analysis using double fourier transform. These complicated methods are not truly analytical, which makes an understanding of parameter influence on time constants difficult. In this paper, a straightforward time domain approach based on stitching of switch intervals piece-wise analytical solutions to a DC modulated H-bridge flying capacitor converter is discussed. This method allows to obtain time-averaged discrete and continuous voltage balance dynamics models. Using small-parameter approximation for pure resistive loads, simple and accurate expressions for voltage balance time constants are deduced, revealing their dependence on load parameters, carrier frequency and duty ratio

An area-time efficient FPGA-implementation of online finite-set model based predictive controllers for flying capacitor inverters

Recently there has been an increase in the use of model-based predictive control (MBPC) for power-electronic converters. Especially for flying-capacitor multilevel converters (FCC) this offers an interesting possibility to simultaneously control output current and the capacitor voltages. The computational burden however is very high and often restrictive for a good implementation. In this paper a time and resource efficient design methodology is presented for the FPGA implementation of FCC MBPC. The control is fully implemented in programmable digital logic. Due to a parallel processing for the three converter phases and a fully pipelined calculation of the prediction stage an area-time efficient implementation is realized. Furthermore, this is achieved by using a high-level design tool. The implementation aspects for 3, 4 and 5-level FC inverters are discussed, with a focus on the 4-level case

Self-precharge in single-leg flying capacitor converters

Flying Capacitor (FC) multilevel pulse width modulated (PWM) converters are an attractive choice due to the natural voltage balance property. During start-up of the converter, care has to be taken that the power switches are not exposed to voltage overstress due to uncharged capacitors. A flying capacitor self-precharge technique is proposed which, by making use of natural balancing and a DC-bus rate control, makes the capacitors balance with a zero average load current. The DC-bus rate control depends on the capacitor voltage balance dynamics. The regular PWM natural balancing technique gives good results for even-level single-leg converter self-precharge, for odd-level converters a special switching pattern is necessary

Navigating Through the Maze of Business Process Change Methods

Business Process Management (BPM) is an approach adopted by many organizations for improving their business processes in order to serve their customers more efficiently and effectively. Literature on BPM offers a plethora of methods used as a guide when improving business processes. Some are promoted as methods for process reengineering, while others as methods for improvement, redesign, or innovation. The number of BPM methods is overwhelming, such that organizations are faced with the challenge to select one that best fits their needs. In this paper, we follow a systematic literature review approach to investigate the characteristics of existing BPM methods. We find that the ambition, nature and perspective of the methods are important to determine whether they can be used for radical or incremental process change. Our findings point to the lack of research done on methods for radical process change

On the evaluation of 'saving-consumption' plans.

Knowledge of the distribution function of the stochastically compounded value of a series of future (positive and/or negative) payments is needed for solving several problems in an insurance or finance environment, see e.g. Dhaene et al. (2002 a,b). In Kaas et al. (2000), convex lower bound approximations for such a sum have been proposed. In case of changing signs of the payments however, the distribution function or the quantiles of the lower bound are not easy to determine, as the approximation for the random compounded value of the payments will in general not be a comonotonic sum. In this paper, we present a method for determining accurate and easy computable approximations for risk measures of such a sum, in case one first has positive payments (savings), followed by negative ones (consumptions). This particular cashflow pattern is observed in 'saving - consumption' plans. In such a plan, a person saves money on a regular basis for a certain number of years. The amount available at the end of this period is then used to generate a yearly pension for a fixed number of years. Using the results of this paper one can find accurate and easy to compute answers to questions such as: 'What is the minimal required yearly savings effort a during a fixed number of years, such that one will be able to meet, with a probability of at least (1 - e), a given consumption pattern during the withdrawal period ?'Research; Evaluation; Knowledge; Distribution; Value; Problems; Insurance; Approximation; Sign; Quantile; Risk; Risk measure; Consumption; Probability;

Comparing approximations for risk measures of sums of non-independent lognormal random variables.

In this paper, we consider different approximations for computing the distribution function or risk measures related to a sum of non-independent lognormal random variables. Approximations for such sums, based on the concept of comonotonicity, have been proposed in Dhaene et al. (2002a,b). These approximations will be compared with two well-known moment matching approximations: the lognormal and the reciprocal Gamma approximation. We find that for a wide range of parameter values the comonotonic lower bound approximation outperforms the two classical approximations.Approximation; Choice; Comonotonicity; Criteria; Decision; Distribution; Dual theory; Lognormal; Market; Moment matching; Optimal; Order; Portfolio; Problems; Random variables; Reciprocal gamma; Research; Risk; Risk measure; Selection; Simulation; Theory; Time; Value; Variables;