Comparison between Multiobjective Population-Based Algorithms in Mechanical Problem

2011 ◽  
Vol 110-116 ◽  
pp. 2383-2389
Author(s):  
H.E. Radhi ◽  
S.M. Barrans
Keyword(s):  
Performance Metrics ◽  
Graphical Representation ◽  
Fitness Function ◽  
Average Distance ◽  
Optimization Methods ◽  
Population Based ◽  
Pareto Solutions ◽  
Numerical Performance ◽  
Definition Of ◽  
Pareto Fronts

The objective of this paper was to perform a comparative study among multiobjective optimization methods on practical problem by using modeFRONTIER optimization software, to determine the efficiency of each method. In order to measure the effectiveness and competence of each method, the lifting arm problem was chosen from the literature [1]. Two numerical performance metrics and one visual criterion were chosen for qualitative and quantitative comparisons:(1) the variance of solution distribution in the Pareto optimal regions, (2) the ratio between the number of resulting Pareto front members to total numbers fitness function calculations which is denoted by hit rate [2], and lastly (3) graphical representation of the Pareto fronts for discussion. These metrics were chosen to represent the quality, as well as speed of the algorithms by ensuring well extends solutions. The definition of the variance as the sum of the square difference between the distance of each Pareto solutions and the average distance between Pareto solutions, over the total number of Pareto solutions. Comparisons among the results obtained using different algorithms have been performed to verify their performance. The experiments carried out indicate that FMOGA-II obtains remarkable results regarding all metrics used.

Missing Data - Better "Not to Have Them", but What If You Do? (Part 1)

Marketing ZFP ◽  
2019 ◽  
Vol 41 (4) ◽  
pp. 21-32
Author(s):  
Dirk Temme ◽  
Sarah Jensen
Keyword(s):  
Missing Data ◽  
Statistical Power ◽  
Missing Values ◽  
Graphical Representation ◽  
Marketing Research ◽  
Likelihood Estimation ◽  
Parameter Estimates ◽  
Full Information Maximum Likelihood ◽  
Definition Of ◽  
Traditional Approaches

Missing values are ubiquitous in empirical marketing research. If missing data are not dealt with properly, this can lead to a loss of statistical power and distorted parameter estimates. While traditional approaches for handling missing data (e.g., listwise deletion) are still widely used, researchers can nowadays choose among various advanced techniques such as multiple imputation analysis or full-information maximum likelihood estimation. Due to the available software, using these modern missing data methods does not pose a major obstacle. Still, their application requires a sound understanding of the prerequisites and limitations of these methods as well as a deeper understanding of the processes that have led to missing values in an empirical study. This article is Part 1 and first introduces Rubin’s classical definition of missing data mechanisms and an alternative, variable-based taxonomy, which provides a graphical representation. Secondly, a selection of visualization tools available in different R packages for the description and exploration of missing data structures is presented.

scholarly journals Adaptive Gene Level Mutation

Algorithms ◽  
2021 ◽  
Vol 14 (1) ◽  
pp. 16
Author(s):  
Jalal Al-afandi ◽  
Horváth András
Keyword(s):  
Genetic Algorithms ◽  
Stochastic Optimization ◽  
Specific Problem ◽  
Traditional Approach ◽  
Fitness Function ◽  
Optimization Methods ◽  
Analytic Solutions ◽  
Problem Representation ◽  
Travelling Salesman ◽  
Gene Level

Genetic Algorithms are stochastic optimization methods where solution candidates, complying to a specific problem representation, are evaluated according to a predefined fitness function. These approaches can provide solutions in various tasks even, where analytic solutions can not be or are too complex to be computed. In this paper we will show, how certain set of problems are partially solvable allowing us to grade segments of a solution individually, which results local and individual tuning of mutation parameters for genes. We will demonstrate the efficiency of our method on the N-Queens and travelling salesman problems where we can demonstrate that our approach always results faster convergence and in most cases a lower error than the traditional approach.

Using single-cell cytometry to illustrate integrated multi-perspective evaluation of clustering algorithms using Pareto fronts

2021 ◽  
Author(s):  
Givanna H Putri ◽  
Irena Koprinska ◽  
Thomas M Ashhurst ◽  
Nicholas J C King ◽  
Mark N Read
Keyword(s):  
Single Cell ◽  
Performance Metrics ◽  
Clustering Algorithms ◽  
Latin Hypercube Sampling ◽  
Supplementary Information ◽  
Sequencing Data ◽  
Evaluation Protocol ◽  
Benchmark Datasets ◽  
Pareto Fronts ◽  
Parameter Values

Abstract Motivation Many ‘automated gating’ algorithms now exist to cluster cytometry and single-cell sequencing data into discrete populations. Comparative algorithm evaluations on benchmark datasets rely either on a single performance metric, or a few metrics considered independently of one another. However, single metrics emphasize different aspects of clustering performance and do not rank clustering solutions in the same order. This underlies the lack of consensus between comparative studies regarding optimal clustering algorithms and undermines the translatability of results onto other non-benchmark datasets. Results We propose the Pareto fronts framework as an integrative evaluation protocol, wherein individual metrics are instead leveraged as complementary perspectives. Judged superior are algorithms that provide the best trade-off between the multiple metrics considered simultaneously. This yields a more comprehensive and complete view of clustering performance. Moreover, by broadly and systematically sampling algorithm parameter values using the Latin Hypercube sampling method, our evaluation protocol minimizes (un)fortunate parameter value selections as confounding factors. Furthermore, it reveals how meticulously each algorithm must be tuned in order to obtain good results, vital knowledge for users with novel data. We exemplify the protocol by conducting a comparative study between three clustering algorithms (ChronoClust, FlowSOM and Phenograph) using four common performance metrics applied across four cytometry benchmark datasets. To our knowledge, this is the first time Pareto fronts have been used to evaluate the performance of clustering algorithms in any application domain. Availability and implementation Implementation of our Pareto front methodology and all scripts and datasets to reproduce this article are available at https://github.com/ghar1821/ParetoBench. Supplementary information Supplementary data are available at Bioinformatics online.

scholarly journals Cardiovascular disease prevalence in type 2 diabetes – an analysis of a large German statutory health insurance database

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Maximilian Gabler ◽  
Silke Geier ◽  
Lukas Mayerhoff ◽  
Wolfgang Rathmann
Keyword(s):  
Type 2 Diabetes ◽  
Cardiovascular Disease ◽  
Health System ◽  
Cardiovascular Complications ◽  
Population Based ◽  
Stratified Sample ◽  
Icd 10 ◽  
Definition Of ◽  
Observation Period

Abstract Background The aim of this study was to determine the prevalence of cardiovascular disease in persons with type 2 diabetes mellitus (T2D) in Germany. Methods A claims database with an age- and sex-stratified sample of nearly 4 million individuals insured within the German statutory health system was used. All patients aged ≥18 years with T2D documented between 1 January 2015 and 31 December 2015 and complete retrospective documentation of ≥5 years (continuous enrollment in the German statutory health system) before 2015 were selected based on a validated algorithm. Cardiovascular disease (CVD) events were identified based on ICD-10 and OPS codes according to a previous clinical study (EMPA-REG OUTCOME trial). Results The prevalence of T2D in Germany in 2015 was 9.9% (n = 324,708). Using a narrow definition of CVD, the 6-year observation period prevalence of CVD was estimated as 46.7% [95% CI: 46.52%;46.86%]. Applying a wider CVD definition, the proportion of T2D patients who showed a history of CVD was 57.1% [95% CI: 56.9%;57.24%]. The prevalence of CVD in patients with T2D ranged from 36.3 to 57.1%, depending on the observation period and definition of CVD. Conclusions The results underline the need for a population-based registration of cardiovascular complications in T2D.

Optimization Design of Trusses Based on Covariance Matrix Adaptation Evolution Strategy Algorithm

2012 ◽  
Vol 215-216 ◽  
pp. 133-137
Author(s):  
Guo Shao Su ◽  
Yan Zhang ◽  
Zhen Xing Wu ◽  
Liu Bin Yan
Keyword(s):  
Stochastic Optimization ◽  
Covariance Matrix ◽  
Optimization Problems ◽  
Fitness Function ◽  
Optimization Methods ◽  
Evolution Strategy ◽  
Covariance Matrix Adaptation ◽  
Study Results ◽  
Highly Nonlinear ◽  
Adaptation Evolution

Covariance matrix adaptation evolution strategy algorithm (CMA-ES) is a newly evolution algorithm. It has become a powerful tool for solving highly nonlinear multi-peak optimization problems. In many real-world optimization problems, the location of multiple optima is often required in a search space. In order to evaluate the solution, thousands of fitness function evaluations are involved that is a time consuming or expensive processes. Therefore, conventional stochastic optimization methods meet a special challenge for a very large number of problem function evaluations. Aiming to overcome the shortcoming of stochastic optimization methods in the high calculation cost, a truss optimal method based on CMA-ES algorithm is proposed and applied to solve the section and shape optimization problems of trusses. The study results show that the method is feasible and has the advantages of high accuracy, high efficiency and easy implementation.

scholarly journals Prevalence and burden of chronic bronchitis symptoms: results from the BOLD study

2017 ◽  
Vol 50 (5) ◽  
pp. 1700621 ◽  
Author(s):  
Filip Mejza ◽  
Louisa Gnatiuc ◽  
A. Sonia Buist ◽  
William M. Vollmer ◽  
Bernd Lamprecht ◽  
...  
Keyword(s):  
Lung Function ◽  
Lung Disease ◽  
Chronic Bronchitis ◽  
Airflow Obstruction ◽  
Population Based ◽  
Normal Lung ◽  
Increased Risk ◽  
Potential Risk Factors ◽  
Definition Of ◽  
Disease Study

We studied the prevalence, burden and potential risk factors for chronic bronchitis symptoms in the Burden of Obstructive Lung Disease study.Representative population-based samples of adults aged ≥40 years were selected in participating sites. Participants completed questionnaires and spirometry. Chronic bronchitis symptoms were defined as chronic cough and phlegm on most days for ≥3 months each year for ≥2 years.Data from 24 855 subjects from 33 sites in 29 countries were analysed. There were significant differences in the prevalence of self-reported symptoms meeting our definition of chronic bronchitis across sites, from 10.8% in Lexington (KY, USA), to 0% in Ile-Ife (Nigeria) and Blantyre (Malawi). Older age, less education, current smoking, occupational exposure to fumes, self-reported diagnosis of asthma or lung cancer and family history of chronic lung disease were all associated with increased risk of chronic bronchitis. Chronic bronchitis symptoms were associated with worse lung function, more dyspnoea, increased risk of respiratory exacerbations and reduced quality of life, independent of the presence of other lung diseases.The prevalence of chronic bronchitis symptoms varied widely across the studied sites. Chronic bronchitis symptoms were associated with significant burden both in individuals with chronic airflow obstruction and those with normal lung function.

scholarly journals Serum IGF1, metabolic syndrome, and incident cardiovascular disease in older people: a population-based study

2013 ◽  
Vol 168 (3) ◽  
pp. 393-401 ◽  
Author(s):  
Christa C van Bunderen ◽  
Mirjam M Oosterwerff ◽  
Natasja M van Schoor ◽  
Dorly J H Deeg ◽  
Paul Lips ◽  
...  
Keyword(s):  
Metabolic Syndrome ◽  
Older People ◽  
Population Based ◽  
Mortality Data ◽  
The Metabolic Syndrome ◽  
Longitudinal Aging Study Amsterdam ◽  
Aging Study ◽  
Definition Of ◽  
Relationship Of ◽  
The Relationship

ObjectiveHigh as well as low levels of IGF1 have been associated with cardiovascular diseases (CVD). The relationship of IGF1 with (components of) the metabolic syndrome could help to clarify this controversy. The aims of this study were: i) to investigate the association of IGF1 concentration with prevalent (components of) the metabolic syndrome; and ii) to examine the role of (components of) the metabolic syndrome in the relationship between IGF1 and incident CVD during 11 years of follow-up.MethodsData were used from the Longitudinal Aging Study Amsterdam, a cohort study in a representative sample of the Dutch older population (≥65 years). Data were available in 1258 subjects. Metabolic syndrome was determined using the definition of the US National Cholesterol Education Program Adult Treatment Panel III. CVD were ascertained by self-reports and mortality data.ResultsLevels of IGF1 in the fourth quintile were associated with prevalent metabolic syndrome compared with the lowest quintile (odds ratio: 1.59, 95% confidence interval (CI) 1.09–2.33). The middle up to the highest quintile of IGF1 was positively associated with high triglycerides in women. Metabolic syndrome was not a mediator in the U-shaped relationship of IGF1 with CVD. Both subjects without the metabolic syndrome and low IGF1 levels (hazard ratio (HR) 1.75, 95% CI 1.12–2.71) and subjects with the metabolic syndrome and high IGF1 levels (HR 2.28, 95% CI 1.21–4.28) demonstrated increased risks of CVD.ConclusionsIn older people, high-normal IGF1 levels are associated with prevalent metabolic syndrome and high triglycerides. Furthermore, this study suggests the presence of different pathomechanisms for both low and high IGF1 levels and incident CVD.

Abstract 17116: Incidence and Outcomes of Out-of-hospital Maternal Cardiac Arrest and Compliance With Resuscitation Guidelines

Circulation ◽  
2015 ◽  
Vol 132 (suppl_3) ◽  
Author(s):  
Alan A Lipowicz ◽  
Sheldon Cheskes ◽  
Sarah H Gray ◽  
Farida Jeejeebhoy ◽  
Janice Lee ◽  
...  
Keyword(s):  
Cardiac Arrest ◽  
Performance Metrics ◽  
Point Of Care ◽  
Survival Rates ◽  
Rare Event ◽  
Population Based ◽  
Childbearing Age ◽  
Child Bearing ◽  
Resuscitation Guidelines ◽  
Regional Health Authorities

Background: Published survival rates after out-of-hospital cardiac arrests (OHCA) are lower than in-hospital cardiac arrest (IHCA). Current estimates for the incidence and rate of survival for maternal cardiac arrest are published only for IHCA. There are no studies that report the incidence and outcomes of maternal OHCA. Current cardiopulmonary resuscitation guidelines contain specific maternal recommendations, although compliance with recommended benchmarks has not been reported. The objective of this study was to report maternal OHCA incidence, outcomes, and compliance with resuscitation and maternal specific guidelines. Methods: This was a population-based cohort study of consecutive maternal OHCA between May 2010 and April 2014. The denominator was estimated from the total regional population of all women of childbearing age obtained from census and age-specific pregnancy rates provided by regional health authorities. Resuscitation performance was measured against the 2010 AHA Guidelines. Results: A total of 6 maternal OHCA occurred amongst 1,085 OHCA occurring in females of child bearing age (15-49) over 4yrs; Incidence-1.85:100,000 (95% CI 1.76 to 1.95) vs. 19.4 per 100,000 (95% CI, 19.37 to 19.43). Maternal and neonatal survival to discharge was 16.7% and 33.3%, respectively. Compliance with CPR quality metrics averaged 83% with a range from 75% to 100%. Compliance with maternal-specific resuscitation guidelines averaged 46.9%, with a range from 0% to 100%. The only performance metrics with 100% compliance was intravenous line insertion above the diaphragm and prehospital activation of the maternal cardiac arrest team. Uterine displacement compliance was low at 0%. Conclusion: The incidence of maternal OHCA was 1.85:100,000, which is lower than the published estimate for maternal IHCA. Survival after OHCA for mother and for child was higher than OHCA occurring in non-pregnant adult females of child bearing age; however, the number of survivors was small (<5). Compliance rates with recommended resuscitation guidelines were high, yet compliance with maternal-specific guidelines were low suggesting targeted training and implementation optimization at the point of care is required to prepare for this rare event involving two lives.

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