On-line multiobjective automatic control system generation by evolutionary algorithms

Evolutionary algorithms are applied to the on- line generation of servo-motor control systems. In this paper, the evolving population of controllers is evaluated at run-time via hardware in the loop, rather than on a simulated model. Disturbances are also introduced at run-time in order to pro- duce robust performance. Multiobjective optimisation of both PI and Fuzzy Logic controllers is considered. Finally an on-line implementation of Genetic Programming is presented based around the Simulink standard blockset. The on-line designed controllers are shown to be robust to both system noise and ex- ternal disturbances while still demonstrating excellent steady- state and dvnamic characteristics

An engineering approach to modelling of dynamic insulation using ESP-r

The use of Dynamic Insulation (DI) can enable recovery of conduction heat loss through a building envelope. This is an active process that allows air to move through the fabric against the temperature gradient. Additionally it promises better indoor air quality, primarily due to filtration properties of the construction material [11]. This paper is concerned with quantifying the energy savings and enhancement of human comfort if this technology is integrated into a building. To ascertain the impact of the technology on whole-building performance, it is necessary to undertake detailed dynamic modelling. A suitable building and plant simulation computer tool (ESP-r) was employed to do this. A technique for modelling the dynamic insulation was developed and validated against known analytical solutions. A full-size test house was then simulated, in the UK climate, with and without DI. Comparative results show that better thermal comfort and energy savings are possible with the use of DI. The results obtained have been translated into suggestions for best practice

Uncertain Technological Change under Capital Mobility

The analysis in this paper shows that unpredictable variations in economic productivity may have a positive or negative effect on the average growth rate of output. This theoretical ambiguity result is not solely determined by the value of the elasticity of intertemporal substitution (of consumption) - as is the case in earlier analyses - but depends on two factors. That is, the growth-uncertainty relationship depends on whether returns to scale in knowledge creation are increasing or non-increasing and whether the elasticity of intertemporal substitution (of profits) is higher or lower than some critical value. Empirical studies concerning these two factors indicate that unpredictable variations in economic productivity have a negative effect on the average long-run growth rate

Endogenous Technological Change under Uncertainty

How does risk or uncertainty in the productivity of research affect the growth rate of the economy? To answer this question, a model of endogenous technological change is used where sustained growth stems from intentional investments in R&D from profit-maximizing firms. The uncertainty arises from the productivity of these investments in R&D. The main result of this analysis is that the relationship between long-run growth and uncertainty (on the productivity of knowledge creation) depends on two main factors - the returns to scale in knowledge creation (increasing or non-increasing) and the value of the elasticity of intertemporal substitution (higher or lower than some critical value).Based on empirical studies on the returns to scale in knowledge creation ("non-increasing") and the value of the elasticity of intertemporal substitution ("higher than the critical value"), we expect a negative relationship between long-run growth and uncertainty regarding the productivity of knowledge creation

On Taxation in a Two-Sector Endogenous Growth Model with Endogenous Labor Supply

This paper examines the effects of taxation on long-run growth in a two-sector endogenous growth model with (i) physical capital as an input in the education sector and (ii) leisure as an additional argument in the utility function. The analysis of the effects of taxation - including income taxation, capital income taxation and labor income taxation - distinguishes between the case with a unique (interior) balanced growth path and the case with multiple balanced growth paths. Due to the flexibility of labor supply, taxation of income may induce agents to spend more or less time on leisure activities. In the case of income taxation, where capital and labor income are taxed equally, the resulting effect on the growth rate is negative. The contribution of endogenous leisure is confined to reducing or increasing the size of the effect on the growth rate. If only capital income is taxed, the direction of the effect may reverse. In that case, the positive effect of the increase in total non-leisure time dominates the direct negative effect, implying that capital taxation increases the long-run growth rate

Class Action Suits and Social Change: The Organization and Impact of the Hill-Burton Cases

Symposium: The Sociology of Class Actions NOTE: A printing error labeled this issue Spring 1982, when it should have been labeled Summer 198

Influence of Vehicle Traffic Emissions on Spatial Variation of Ozone and its Precursors in Air of Port Harcourt City, Nigeria

This study aimed at assessing the influence of vehicle traffic on spatial variation of ozone (O3) and its vehicular emission precursors in the air of Port Harcourt city. Sampling was carried out in ten (10) sites, eight (8) located within the high traffic density area (study sites) and two (2) located within the very low traffic density area (reference sites). The precursor pollutants measured were nitrogen dioxide (NO2), carbon monoxide (CO) and volatile organic compounds (VOCSs). Ozone and the precursor pollutants were measured in situ using AeroQUAL 500 series portable ambient air analyzer while traffic flow survey was achieved by direct counting. Measurements were carried out at morning, evening and off-peak traffic periods respectively. The mean concentrations of ozone and the precursor pollutants were significantly higher (p = 0.05) in the study sites than in the reference sites. Mean concentrations were higher at peak traffic periods than at off-peak traffic periods except for ozone that was higher at off-peak than at morning peak. There was significant correlation between traffic density and each of the pollutants including ozone. The spatial variability in concentration of pollutants was influenced by vehicular traffic. VOCs and NO2 levels were higher than the National Ambient Air Quality Standard (NAAQS) limit of 0.05 ppm and 0.04 – 0.06 ppm respectively, O3 concentration was below the standard limit (0.06 ppm) but was at the verge of exceeding. Traffic emission within the city was significant and could be mitigated through regular monitoring and control

Psychometric Properties of the Grief Cognitions Questionnaire for Children (GCQ-C)

Negative thinking is seen as an important mediating factor in the development of prolonged grief disorder (PGD), a syndrome encompassing debilitating symptoms of grief. No measure of specific grief related cognitions is available yet. Based on an adult measure of negative thinking in adults we developed a questionnaire for children, the Grief Cognitions Questionnaire for Children (GCQ-C). This study investigated several psychometric properties of the GCQ-C. Both reliability and validity were investigated in this study, in which hundred fifty-one children and adolescents (aged 8–18 years) participated. Findings showed that items of the GCQ-C represented one underlying dimension. Furthermore, the internal consistency and temporal stability were found to be adequate. Third, the findings supported the concurrent validity (e.g., significant positive correlations with self-report indices of PGD, depression and posttraumatic stress disorder), convergent and divergent validity of the GCQ-C. This study provides further evidence for the importance of negative thinking in PGD in children and adolescents

List Coloring in the Absence of Two Subgraphs

list assignment of a graph G = (V;E) is a function L that assigns a list L(u) of so-called admissible colors to each u 2 V . The List Coloring problem is that of testing whether a given graph G = (V;E) has a coloring c that respects a given list assignment L, i.e., whether G has a mapping c : V ! f1; 2; : : :g such that (i) c(u) 6= c(v) whenever uv 2 E and (ii) c(u) 2 L(u) for all u 2 V . If a graph G has no induced subgraph isomorphic to some graph of a pair fH1;H2g, then G is called (H1;H2)-free. We completely characterize the complexity of List Coloring for (H1;H2)-free graphs