Multilevel Training of Binary Morphological Operators

The design of binary morphological operators that are translation-invariant and locally defined by a finite neighborhood window corresponds to the problem of designing Boolean functions. As in any supervised classification problem, morphological operators designed from a training sample also suffer from overfitting. Large neighborhood tends to lead to performance degradation of the designed operator. This work proposes a multilevel design approach to deal with the issue of designing large neighborhood-based operators. The main idea is inspired by stacked generalization (a multilevel classifier design approach) and consists of, at each training level, combining the outcomes of the previous level operators. The final operator is a multilevel operator that ultimately depends on a larger neighborhood than of the individual operators that have been combined. Experimental results show that two-level operators obtained by combining operators designed on subwindows of a large window consistently outperform the single-level operators designed on the full window. They also show that iterating two-level operators is an effective multilevel approach to obtain better results.

Socio-economic inequalities in women's fruit and vegetable intakes: a multilevel study of individual, social and environmental mediators

Objective: This study employed a multilevel design to test the contribution of individual, social and environmental factors to mediating socio-economic status (SES) inequalities in fruit and vegetable consumption among women. Design: A cross-sectional survey was linked with objective environmental data. Setting: A community sample involving 45 neighbourhoods. Subjects: In total, 1347 women from 45 neighbourhoods provided survey data on their SES (highest education level), nutrition knowledge, health considerations related to food purchasing, and social support for healthy eating. These data were linked with objective environmental data on the density of supermarkets and fruit and vegetable outlets in local neighbourhoods. Results: Multilevel modelling showed that individual and social factors partly mediated, but did not completely explain, SES variations in fruit and vegetable consumption. Store density did not mediate the relationship of SES with fruit or vegetable consumption. Conclusions: Nutrition promotion interventions should focus on enhancing nutrition knowledge and health considerations underlying food purchasing in order to promote healthy eating, particularly among those who are socio-economically disadvantaged. Further investigation is required to identify additional potential mediators of SES-diet relationships, particularly at the environmental level. © The Authors 2006.

Informatietechnologisch ontwerp van een PDKS®: begrippen, structuur, werkwijzen en gebruik in de praktijk

Een Pedagogisch-Didactische KernStructuur® (PDKS®) bestaat uit een diagnostische, met name op kerndoelen en curriculumspecificaties gebaseerde systematiek voor het ontwerpen en realiseren van ‘Optimaliserend Onderwijs’ en de bijbehorende speel-/leerprocessen voor elk kind of elke leerling. In dit document wordt een nieuw ontwerp van een praktijkgerichte PDKS®-systematiek uitgewerkt die is ingebed in een webapplicatie ten behoeve van gebruik in instellingen voor vóór- en vroegschoolse educatie en in scholen voor PO en VO. Doel van dit digitale curriculumbeheersysteem is om het voor genoemde instellingen, scholen en leerkrachten / docenten gemakkelijker te maken het onderwijs en de speel-/leerprocessen verantwoord te individualiseren. Dit wil zeggen: deze onderwijs- en leerprocessen adequaat voor te bereiden en in te zetten ter ondersteuning van de ontwikkeling en de leerbehoefte, het leerniveau en het leertempo van individuele leerlingen en groepjes leerlingen in een flexibel groeps- of klasverband. De groeps- of klasorganisatie van leerlingen wordt onafhankelijk(er) van leeftijd en leerlingen kunnen verantwoord, individueel of samen, de eigen speel-/leerprocessen méér zelf reguleren. Via de hier ontwikkelde, informatietechnologisch ingebedde PDKS® kunnen essentiële onderwijs- en leerprocessen worden geïntegreerd. Bijvoorbeeld diagnostiek gebaseerd op individuele én landelijke indicatoren (dubbele diagnostiek), passende instructie en speel-/leerprocessen, vrije curriculumactiviteiten, curriculuminformatie en -beheer, en systematische evaluatie op verschillende onderwijsniveaus (leerling, groepje, groep/klas, school, bovenschools, landelijk). Samenwerking met jeugdzorg wordt eenduidiger, gemakkelijker en méér preventief. De combinatie van resultaten van landelijk genormeerde toetsing en de schoolgebonden evaluatie van leerarrangementen levert tevens concreet zicht op de feitelijke ‘schoolkwaliteit’.

Optimaliseren van leren in en rond PO, VO en MBO.

In deze presentatie wordt ingegaan op mogelijkheden het onderwijs voor en het leren van jonge kinderen en leerlingen in het PO, VO en MBO te optimaliseren.

Electromagnetic and thermal design of a multilevel converter with high power density and reliability

Electric energy demand has been growing constantly as the global population increases. To avoid electric energy shortage, renewable energy sources and energy conservation are emphasized all over the world. The role of power electronics in energy saving and development of renewable energy systems is significant. Power electronics is applied in wind, solar, fuel cell, and micro turbine energy systems for the energy conversion and control. The use of power electronics introduces an energy saving potential in such applications as motors, lighting, home appliances, and consumer electronics. Despite the advantages of power converters, their penetration into the market requires that they have a set of characteristics such as high reliability and power density, cost effectiveness, and low weight, which are dictated by the emerging applications. In association with the increasing requirements, the design of the power converter is becoming more complicated, and thus, a multidisciplinary approach to the modelling of the converter is required. In this doctoral dissertation, methods and models are developed for the design of a multilevel power converter and the analysis of the related electromagnetic, thermal, and reliability issues. The focus is on the design of the main circuit. The electromagnetic model of the laminated busbar system and the IGBT modules is established with the aim of minimizing the stray inductance of the commutation loops that degrade the converter power capability. The circular busbar system is proposed to achieve equal current sharing among parallel-connected devices and implemented in the non-destructive test set-up. In addition to the electromagnetic model, a thermal model of the laminated busbar system is developed based on a lumped parameter thermal model. The temperature and temperature-dependent power losses of the busbars are estimated by the proposed algorithm. The Joule losses produced by non-sinusoidal currents flowing through the busbars in the converter are estimated taking into account the skin and proximity effects, which have a strong influence on the AC resistance of the busbars. The lifetime estimation algorithm was implemented to investigate the influence of the cooling solution on the reliability of the IGBT modules. As efficient cooling solutions have a low thermal inertia, they cause excessive temperature cycling of the IGBTs. Thus, a reliability analysis is required when selecting the cooling solutions for a particular application. The control of the cooling solution based on the use of a heat flux sensor is proposed to reduce the amplitude of the temperature cycles. The developed methods and models are verified experimentally by a laboratory prototype.

Power losses analysis and cooling system design of three topologies of multilevel inverters

This paper presents the comparison of three topologies of multilevel inverters applied to drive an induction motor of 500 kVA/4.16 kV. The multilevel inverters analyzed are: a neutral point clamped inverter, a symmetrical cascaded multilevel inverter and a hybrid asymmetrical cascaded multilevel inverter. The performance indexes used in the comparison are total harmonic distortion, first order distortion factor, semiconductors power losses distribution and heat-sink volume. The comparison is developed with the purpose of finding the efficiency and the heat-sink volume where the three systems present the same output filter. ©2008 IEEE.

Addressing Multilevel Program Complexity by Evaluation Design

In this paper, we present the evaluation design for a complex multilevel program recently introduced in Switzerland. The evaluation embraces the federal level, the cantonal program level, and the project level where target groups are directly addressed. We employ Pawson and Tilley’s realist evaluation approach, in order to do justice to the varying context factors that impact the cantonal programs leading to varying effectiveness of the implemented activities. The application of the model to the canton of Uri shows that the numerous vertical and horizontal relations play a crucial role for the program’s effectiveness. As a general learning for the evaluation of complex programs, we state that there is a need to consider all affected levels of a program and that no monocausal effects can be singled out in programs where multiple interventions address the same problem. Moreover, considering all affected levels of a program can mean going beyond the borders of the actual program organization and including factors that do not directly interfere with the policy delivery as such. In particular, we found that the relationship between the cantonal and the federal level was a crucial organizational factor influencing the effectiveness of the cantonal program.

Design of multilevel amplitude regenerative system

We propose a scheme for multilevel (nine or more) amplitude regeneration based on a nonlinear optical loop mirror (NOLM) and demonstrate through numerical modeling its efficiency and cascadability on circular 16-, 64-, and 256- symbol constellations. We show that the amplitude noise is efficiently suppressed. The design is flexible and enables variation of the number of levels and their positioning. The scheme is compatible with phase regenerators. Also, compared to the traditional single-NOLM configuration scheme, new features, such as reduced and sign-varied power-dependent phase shift, are available. The model is simple to implement, as it requires only two couplers in addition to the traditional NOLM, and offers a vast range of optimization parameters. © 2014 Optical Society of America.

Grid Integration of Offshore Wind Farms Using Modular Marx Multilevel Converters

This paper proposes the use of a Modular Marx Multilevel Converter, as a solution for energy integration between an offshore Wind Farm and the power grid network. The Marx modular multilevel converter is based on the Marx generator, and solves two typical problems in this type of multilevel topologies: modularity and dc capacitor voltage balancing. This paper details the strategy for dc capacitor voltage equalization. The dynamic models of the converter and power grid are presented in order to design the converter ac output voltages and the dc capacitor voltage controller. The average current control is presented and used for power flow control, harmonics and reactive power compensation. Simulation results are presented in order to show the effectiveness of the proposed (MC)-C-3 topology.

Design effect and interviewer effects: Evidence from the Spanish ESS3-2006 Data

In 2007 the first Quality Enhancement Meeting on sampling in the European SocialSurvey (ESS) took place. The discussion focused on design effects and inteviewereffects in face-to-face interviews. Following the recomendations of this meeting theSpanish ESS team studied the impact of interviewers as a new element in the designeffect in the response s variance using the information of the correspondent SampleDesign Data Files. Hierarchical multilevel and cross-classified multilevel analysis areconducted in order to estimate the amount of responses variation due to PSU and tointerviewers for different questions in the survey. Factor such as the age of theinterviewer, gender, workload, training and experience and respondent characteristicssuch as age, gender, renuance to participate and their possible interactions are alsoincluded in the analysis of some specific questions like trust in politicians and trustin legal system . Some recomendations related to future sampling designs and thecontents of the briefing sessions are derived from this initial research.

Multilevel Analysis of Trunk Surface Measurements for Noninvasive Assessment of Scoliosis Deformities.

Study Design. Reliability study. Objectives. To assess between-acquisition reliability of new multilevel trunk cross sections measurements, in order to define what is a real change when comparing 2 trunk surface acquisitions of a same patient, before and after surgery or throughout the clinical monitoring. Summary of Background Data. Several cross-sectional surface measurements have been proposed in the literature for noninvasive assessment of trunk deformity in patients with adolescent idiopathic scoliosis (AIS). However, only the maximum values along the trunk are evaluated and used for monitoring progression and assessing treatment outcome. Methods. Back surface rotation (BSR), trunk rotation (TR), and coronal and sagittal trunk deviation are computed on 300 cross sections of the trunk. Each set of 300 measures is represented as a single functional data, using a set of basis functions. To evaluate between-acquisition variability at all trunk levels, a test-retest reliability study is conducted on 35 patients with AIS. A functional correlation analysis is also carried out to evaluate any redundancy between the measurements. Results. Each set of 300 measures was successfully described using only 10 basis functions. The test-retest reliability of the functional measurements is good to very good all over the trunk, except above the shoulders level. The typical errors of measurement are between 1.20° and 2.2° for the rotational measures and between 2 and 6 mm for deviation measures. There is a very strong correlation between BSR and TR all over the trunk, a moderate correlation between coronal trunk deviation and both BSR and TR, and no correlation between sagittal trunk deviation and any other measurement. Conclusion. This novel representation of trunk surface measurements allows for a global assessment of trunk surface deformity. Multilevel trunk measurements provide a broader perspective of the trunk deformity and allow a reliable multilevel monitoring during clinical follow-up of patients with AIS and a reliable assessment of the esthetic outcome after surgery.