The impact of population size on the performance of GA

Genetic algorithm (GA) is an artificial intelligence search method that uses the process of evolution and natural selection theory and is under the umbrella of evolutionary computing algorithm. It is an efficient tool for solving optimization problems. Integration among (GA) parameters is vital for successful (GA) search. Such parameters include mutation and crossover rates in addition to population that are important issues in (GA). However, each operator of GA has a special and different influence. The impact of these factors is influenced by their probabilities; it is difficult to predefine specific ratios for each parameter, particularly, mutation and crossover operators. This paper reviews various methods for choosing mutation and crossover ratios in GAs. Next, we define new deterministic control approaches for crossover and mutation rates, namely Dynamic Decreasing of high mutation ratio/dynamic increasing of low crossover ratio (DHM/ILC), and Dynamic Increasing of Low Mutation/Dynamic Decreasing of High Crossover (ILM/DHC). The dynamic nature of the proposed methods allows the ratios of both crossover and mutation operators to be changed linearly during the search progress, where (DHM/ILC) starts with 100% ratio for mutations, and 0% for crossovers. Both mutation and crossover ratios start to decrease and increase, respectively. By the end of the search process, the ratios will be 0% for mutations and 100% for crossovers. (ILM/DHC) worked the same but the other way around. The proposed approach was compared with two parameters tuning methods (predefined), namely fifty-fifty crossover/mutation ratios, and the most common approach that uses static ratios such as (0.03) mutation rates and (0.9) crossover rates. The experiments were conducted on ten Traveling Salesman Problems (TSP). The experiments showed the effectiveness of the proposed (DHM/ILC) when dealing with small population size, while the proposed (ILM/DHC) was found to be more effective when using large population size. In fact, both proposed dynamic methods outperformed the predefined methods compared in most cases tested.

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Assessment of Equity in Access to Percutaneous Coronary Intervention (PCI) Centres in Poland

Healthcare ◽

10.3390/healthcare8020071 ◽

2020 ◽

Vol 8 (2) ◽

pp. 71 ◽

Cited By ~ 1

Author(s):

Justyna Rój ◽

Maciej Jankowiak

Keyword(s):

Percutaneous Coronary Intervention ◽

Population Size ◽

Gini Coefficient ◽

Coronary Intervention ◽

Invasive Procedures ◽

Invasive Treatment ◽

The Gini Coefficient ◽

Invasive Cardiology ◽

Percutaneous Coronary ◽

The Impact

The purpose of this study is to analyse the disparities in the distribution of percutaneous coronary intervention (PCI) centres in Poland and the impact of eventual inequities on access to the invasive treatment of acute myocardial infarctions (AMI). To examine the distribution of PCI centres against population size and geographic size in Poland, the Gini coefficient calculated based on the Lorenz Curve was engaged. In addition, the regression function was employed to estimate the impact of distribution of PCI centres on access to invasive procedures (coronarographies and primary percutaneous coronary intervention). Data were collected from the public statistical system and Polish National Health Fund database for the year 2018. The relation and the level of equity was measured based on the aggregated data at a district (voivodeship) level. The results of the Gini coefficient analysis show that the distribution of invasive cardiology units measured against population size is more equitable than when measured against geographic size. In addition, the regression analysis shows the moderate size of the positive correlation between number of PCI centres per 100,000 population and the number of all categories of the invasive treatment of AMI per 100,000 population, and the lack of similar correlation in case of the number of PCI centres expressed per 1000 km2, which could be evidence of an insufficiency of PCI centres in areas where the concentration of PCI centres per 100,000 population is lower. The main implication for policy makers that results from this research is the need for a correction of PCI centres distribution per 100,000 inhabitants to ensure better access to invasive procedures.

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Demographic Impact on Environment - A Case Study Focussing on CO2 Emission in China

Asia Pacific Journal of Public Health ◽

10.1177/101053959801000205 ◽

1998 ◽

Vol 10 (2) ◽

pp. 81-87

Author(s):

Kenji Hayashi ◽

Jianqun Gao

Keyword(s):

Population Size ◽

Urban Areas ◽

Fossil Fuels ◽

Energy Transition ◽

Population Increase ◽

High Fertility ◽

Economic Activities ◽

The North ◽

Per Capita ◽

The Impact

Carbon dioxide (CO2) emission derived from economic activities results primarily from the fossil fuels consumed. The variety of fossil fuels used, the degree of efficient consumption of energy, economic growth and national population size determine the total amount of CO2 emission in a country. Considering its population size as well as its potential for economic development, China is expected to play a key role in the global warming issue in concert with other industrialized Asian countries, including Japan. In the present study, the impact of population increase on total CO2 emission in China during the period 1982-1990 was analyzed. During the study period, population increase and CO2 emission per capita were 21 per cent and 70 per cent, respectively. In terms of population increase by region, some provinces in the inland areas and megacities, like Shanghai and Beijing, contributed the highest figures. To cope with high fertility in the inland areas as well as massive population inflow into the urban areas simultaneously, increasing the number of medium-sized cities to be located in the inland areas could be a solution. For CO2 emission per capita, the figures for the North-Eastcrn provinces and South-Eastern provinces along the coast are remarkable. The estimate of total emission of CO2 by 2010 is 1.6 million tons, a 74 per cent increase from 1992. Energy transition is the key to the stabilization of CO2 emission in China.

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Fire and its impact on avian population dynamics

Pacific Conservation Biology ◽

10.1071/pc970206 ◽

1997 ◽

Vol 3 (3) ◽

pp. 206 ◽

Cited By ~ 2

Author(s):

G. Barry Baker ◽

E. Belinda Dettmann ◽

Stephen J. Wilson

Keyword(s):

Population Size ◽

Fire Regimes ◽

Long Term Study ◽

Sclerophyll Forest ◽

In Fire ◽

Avian Populations ◽

The Impact ◽

Term Monitoring ◽

Probability Of Capture

Survival rate, population size, recruitment and probability of capture, derived from a long-term study of 20 passerine species in wet sclerophyll forest near Canberra, were used to measure the impact of a high intensity wildfire which burnt 70% of the study area. The wildfire significantly affected the population size of 13 species for a period of up to six years following the fire. Survival and recruitment were the least sensitive measures of impact and indicated a significant response to fire for only 2 of 10 species. We detected measurable effects of the fire for 17 of the 20 species studied. Many of these species had returned to prefire levels within three years, but for nine species the effects were still apparent six years later. Mark-recapture methodology provides an effective way of measuring the impact of fire regimes in forest environments. Long-term monitoring programmes should be established in fire-prone forest environments to contribute toward our understanding of fire, and its effect on avian populations. Such programmes have resource implications and researchers are urged to encourage the participation of the amateur bird banding community to contribute to such projects.

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Ökonomen, Publikationen und Zitationen: Ein europäischer Vergleich

Perspektiven der Wirtschaftspolitik ◽

10.1111/1468-2516.00009 ◽

2000 ◽

Vol 1 (2) ◽

pp. 143-160 ◽

Cited By ~ 6

Author(s):

Reiner Eichenberger ◽

Ursina Meier ◽

Rolf Arpagausz

Keyword(s):

Population Size ◽

European Countries ◽

Scholarly Journals ◽

Publishing Activity ◽

Western European ◽

Number Of Publications ◽

The Impact

Abstract This paper measures the publishing activity and the impact of European economists, 1986±1996. The analysis of the number of publications in selected scholarly journals and the citations shows that, relative to population size, the British economists are in the lead. They publish much more than their German, French and Italian colleagues. At the same time, their work seems also to be cited more often. However, compared to the economists from the small western European countries, the British dominance is much less pronounced. The latter seem to be much more focused on the international academic market than scholars from the large continental countries. 160

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Plant genotypic diversity increases population size of a herbivorous insect

Proceedings of The Royal Society B Biological Sciences ◽

10.1098/rspb.2011.0239 ◽

2011 ◽

Vol 278 (1721) ◽

pp. 3108-3115 ◽

Cited By ~ 42

Author(s):

Shunsuke Utsumi ◽

Yoshino Ando ◽

Timothy P. Craig ◽

Takayuki Ohgushi

Keyword(s):

Population Dynamics ◽

Population Size ◽

Natural Enemy ◽

Genotypic Variation ◽

Genotypic Diversity ◽

Community Genetics ◽

Aphid Population ◽

Herbivorous Insect ◽

Mixed Genotype ◽

The Impact

It is critical to incorporate the process of population dynamics into community genetics studies to identify the mechanisms of the linkage between host plant genetics and associated communities. We studied the effects of plant genotypic diversity of tall goldenrod Solidago altissima on the population dynamics of the aphid Uroleucon nigrotuberculatum . We found genotypic variation in plant resistance to the aphid in our experiments. To determine the impact of plant genotypic diversity on aphid population dynamics, we compared aphid densities under conditions of three treatments: single-genotype plots, mixed-genotype plots and mixed-genotype-with-cages plots. In the latter treatment plants were individually caged to prevent natural enemy attack and aphid movement among plants. The synergistic effects of genotypes on population size were demonstrated by the greater aphid population size in the mixed-genotype treatment than expected from additive effects alone. Two non-exclusive hypotheses are proposed to explain this pattern. First, there is a source–sink relationship among plant genotypes: aphids move from plant genotypes where their reproduction is high to genotypes where their reproduction is low. Second, natural enemy mortality is reduced in mixed plots in a matrix of diverse plant genotypes.

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