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See detailLocal search heuristics for large-scale discrete structural optimization with expensive black-box evaluations
Bay, Maud ULg; Crama, Yves ULg; Rigo, Philippe ULg

Report (2009)

This paper considers large-scale structural optimization problems featuring discrete variables, as well as nonlinear implicit constraints which can only be evaluated through time-expensive computations. A ... [more ▼]

This paper considers large-scale structural optimization problems featuring discrete variables, as well as nonlinear implicit constraints which can only be evaluated through time-expensive computations. A prominent application consists in the preliminary structural design of large ships, where many of the variables take their values in discrete sets which model standard element dimensions to be selected from catalogs, and where the evaluation of the constraints involves a complex structural analysis performed by black-box software. The resulting large-scale nonlinear combinatorial problems are particularly hard, and even nding a discrete feasible solution may prove challenging for some instances. In this paper, we propose two heuristics that combine local search methods and a sequential optimization method based on approximations of the implicit constraints. The heuristics are applied to the structural optimization of several large ships. For these instances, the heuristics provide discrete feasible solutions whose value is close to the optimal value of the continuous relaxation obtained by disregarding the discrete nature of the variables. [less ▲]

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See detailLocal Second Gradient Models and Damage Mechanics: 1D Post-Localization Studies in Concrete Specimens
Kotronis, Panagiotis; Collin, Frédéric ULg; Bésuelle, Pierre et al

in Exadaktylos, G.; Vardoulakis, Ioannis (Eds.) Bifurcations, Instabilities, Degradation in Geomechanics (2007)

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See detailLocal second gradient models and damage mechanics: application to concrete
Kotronis, Panagiotis; Chambon, René; Mazars, Jacky et al

Conference (2005)

The non linear behaviour of concrete is often simulated using local constitutive models based on the continuous damage mechanics theory. This approach however is not adequate for post-localisation studies ... [more ▼]

The non linear behaviour of concrete is often simulated using local constitutive models based on the continuous damage mechanics theory. This approach however is not adequate for post-localisation studies with strain softening. It is well known that spurious mesh dependence appears in computations and cases of failure without energy dissipation. In order to improve computational performance second grade local models are chosen to include a meso scale in the continuous damage model. This approach differs from the nonlocal one in the sense that it is a local theory with higher order stresses depending only on the local cinematic history. 1D numerical computations with concrete specimens are presented. Using a random initialisation of the iterative solver of the equilibrium equation we search the existence of various solutions for the boundary value study and also to see if the second grade term regularise the problem giving results that are mesh insensitive and objective. [less ▲]

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See detailLocal stability results for the collective behaviors of infinite populations of pulse-coupled oscillators
Mauroy, Alexandre ULg; Sepulchre, Rodolphe ULg

in Proceedings of the IEEE Conference on Decision and Control (2011)

In this paper, we investigate the behavior of pulse-coupled integrate-and-fire oscillators. Because the stability analysis of finite populations is intricate, we investigate stability results in the ... [more ▼]

In this paper, we investigate the behavior of pulse-coupled integrate-and-fire oscillators. Because the stability analysis of finite populations is intricate, we investigate stability results in the approximation of infinite populations. In addition to recovering known stability results of finite populations, we also obtain new stability results for infinite populations. In particular, under a weak coupling assumption, we solve for the continuum model a conjecture still prevailing in the finite dimensional case. © 2011 IEEE. [less ▲]

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See detailLocal Stakeholders’ Perceptions About the Introduction of Performance-Based Financing in Benin: A Case Study in Two Health Districts
Paul, Elisabeth ULg; Sossouhounto, Nadine; Eclou, Dieudonné

in International Journal of Health Policy and Management (2014), 3

Background: Performance-Based Financing (PBF) has been advanced as a solution to contribute to improving the performance of health systems in developing countries. This is the case in Benin. This study ... [more ▼]

Background: Performance-Based Financing (PBF) has been advanced as a solution to contribute to improving the performance of health systems in developing countries. This is the case in Benin. This study aims to analyse how two PBF approaches, piloted in Benin, behave during implementation and what effects they produce, through investigating how local stakeholders perceive the introduction of PBF, how they adapt the different approaches during implementation, and the behavioural interactions induced by PBF. Methods: The research rests on a socio-anthropological approach and qualitative methods. The design is a case study in two health districts selected on purpose. The selection of health facilities was also done on purpose, until we reached saturation of information. Information was collected through observation and semi-directive interviews supported by an interview guide. Data was analysed through contents and discourse analysis. Results: The Ministry of Health (MoH) strongly supports PBF, but it is not well integrated with other ongoing reforms and processes. Field actors welcome PBF but still do not have a sense of ownership about it. The two PBF approaches differ notably as for the organs in charge of verification. Performance premiums are granted according to a limited number of quantitative indicators plus an extensive qualitative checklist. PBF matrices and verification missions come in addition to routine monitoring. Local stakeholders accommodate theoretical approaches. Globally, staff is satisfied with PBF and welcomes additional supervision and training. Health providers reckon that PBF forces them to depart from routine, to be more professional and to respect national norms. A major issue is the perceived unfairness in premium distribution. Even if health staff often refer to financial premiums, actually the latter are probably too weak — and ‘blurred’ — to have a lasting inciting effect. It rather seems that PBF motivates health workers through other elements of its ‘package’, especially formative supervisions. Conclusion: If the global picture is quite positive, several issues could jeopardise the success of PBF. It appears crucial to reduce the perceived unfairness in the system, notably through enhancing all facilities’ capacities to ensure they are in line with national norms, as well as to ensure financial and institutional sustainability of the system. [less ▲]

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See detailLocal structure of liquid GeTe via neutron scattering and ab initio simulations
Raty, Jean-Yves ULg; Godlevsky, V. V.; Gaspard, Jean-Pierre ULg et al

in Physical Review. B, Condensed Matter and Materials Physics (2002), 65

We examine the local atomic order as well as some dynamic properties of the semiconducting liquid GeTe. We employ hot-neutron two-axis diffraction at three temperatures above the melting point and compare ... [more ▼]

We examine the local atomic order as well as some dynamic properties of the semiconducting liquid GeTe. We employ hot-neutron two-axis diffraction at three temperatures above the melting point and compare these results with ab initio molecular dynamics simulations. The simulations were based on interatomic forces derived from pseudopotentials constructed within density functional theory. At the melting temperature, the Peierls distortion responsible for the lower-temperature crystal phase is shown to manifest itself within the liquid structure. At higher temperatures in the liquid, increasing disorder in the Ge environment determines the eventual semiconductor-metal transition. The calculated kinematic viscosity of the liquid is found to agree with the experimental value and is shown to arise from the small diffusion coefficient of the Te atoms. [less ▲]

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See detailLocal Structure of Mn in (La1-xHox)2/3Ca1/3MnO3 Studied by X-ray Absorption Fine Structure
Pietnoczka, A.; Pekala, M.; Bacewicz, R. et al

in Acta Physica Polonica A (2010), 117(2), 257-261

Results of X-ray absorption fine structure measurements in manganites (La1-xHox)2/3Ca1/3MnO3 with 0.15 < x < 0.50 are presented. When LaMnO3 is doped with a divalent element such as Ca2+, substituting ... [more ▼]

Results of X-ray absorption fine structure measurements in manganites (La1-xHox)2/3Ca1/3MnO3 with 0.15 < x < 0.50 are presented. When LaMnO3 is doped with a divalent element such as Ca2+, substituting forLa3+, holes are induced in the filled Mn d orbitals. This leads to a strong ferromagnetic coupling between Mn sites. Ca ions in La1-xCaxMnO3 introduce a distortion of the crystal lattice and mixed valence Mn ions (Mn3+ and Mn4+). On the other hand, in manganites (La1-xHox)2/3Ca1/3MnO3 the substitution of La for Ho causes a lattice distortion and induces a disorder, which reduces a magnetic interaction. The ferromagnetic transition temperature and conductivity decrease very quickly with increasing x. The magnetic and transport properties of compounds depend on the local atomic structure around Mn ions. The information on the bond lengths and Debye–Waller factor are obtained from the extended X-ray absorption fine structure (EXAFS) data analysis. The charge state of Mn is determined from the position of the absorption edge in X-ray absorption near edge structure (XANES) data. XAFS results are in good agreement with magnetic characteristics of the studied materials. [less ▲]

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See detailThe Local Time Propagation of Electron and Proton Shock-Induced Aurora and the Role of the Interplanetary Magnetic Field and Solar Wind
Gérard, Jean-Claude ULg

Conference (2004, May 01)

Shock-induced aurora observed with satellite-borne ultraviolet imagers shows distinct characteristics from the more common and extensively studied aurora generated during magnetospheric substorms. It is ... [more ▼]

Shock-induced aurora observed with satellite-borne ultraviolet imagers shows distinct characteristics from the more common and extensively studied aurora generated during magnetospheric substorms. It is initiated in the noon sector immediately following dynamic pressure pulses associated with the arrival of enhanced solar wind plasma at the front of the magnetosphere. The brightness enhancement rapidly propagates toward the dawn and dusk sectors and may trigger the development of an auroral substorm on the nightside. The FUV imaging system on board the IMAGE satellite has the ability to discriminate between proton and electron precipitation. This feature has been used to study the morphology and dynamics of the electron and proton precipitation following pulse-induced magnetospheric perturbations. A set of 14 cases occurring during positive and negative Bz periods has been selected and studied. A different dynamics is observed for aurora caused by electron and proton precipitation. The important role played by the Bz component of the interplanetary magnetic field is analyzed as well. A correlation between the precipitated power deduced from FUV images and solar wind (SW) and interplanetary magnetic field (IMF) measured by ACE is presented. The effect of SW and IMF conditions prevailing before and during the shock on shock aurora is studied separately in order to distinguish the role of the preconditioning of the magnetosphere and the effects induced by the shock itself. The time evolution of the injected power is also studied in the entire oval and in individual MLT sectors. [less ▲]

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See detailLocal vs. wide-area undervoltage load shedding in the presence of induction motor loads
Otomega, Bogdan; Van Cutsem, Thierry ULg

in Proceedings of the IEEE PES PowerTech 2009 conference (2009, July)

In the presence of induction motor loads, long-term voltage instability may end up in a sharp voltage decrease, which makes the tuning of undervoltage load shedding more delicate. This paper first ... [more ▼]

In the presence of induction motor loads, long-term voltage instability may end up in a sharp voltage decrease, which makes the tuning of undervoltage load shedding more delicate. This paper first investigates the ability of a purely distributed load shedding scheme, previously proposed by the authors, to cope with these situations. Owing to difficulties to reconcile dependability and security, an alternative wide-area protection is considered. The latter consists of generators sending overexcitation signals to the load shedding controllers in order to allow the latter to act faster. Detailed time simulations of a test system are reported. [less ▲]

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See detailLocal-Level Monitoring in Decentralized Forest Management: Exploring the Spaces for Community Participation
Tol, Sokchea; Srey, Marona; Diepart, Jean-Christophe ULg

in Beaupre, Pauline; Taylor, Janet; Carson, Toby (Eds.) Emerging Trends, Challenges and Innovations Community Based Natural Resource Management (CBNRM) in Cambodia (2009)

This paper explores a participatory monitoring process initiated in Kampong Thom province with 3 Community Forestry (CF) sites where CF development was facilitated by Forestry Administration (FA) staff ... [more ▼]

This paper explores a participatory monitoring process initiated in Kampong Thom province with 3 Community Forestry (CF) sites where CF development was facilitated by Forestry Administration (FA) staff and externally supported by German Technical Support-Rural Development Programme (GTZ-RDP).The paper details the methodology used and the key outputs produced during the process, it highlights the four main principles of the principle, criteria, and indicator Monitoring and Evaluation (M&E) which are: (1) that forest health is maintained, (2) public well-being is improved, (3) community well-being is assured, and (4) external support is effective. The results show that in all three CF, the land integrity and the forest resource itself was improved between the baseline and follow-up surveys. Despite the positive results, many of the challenges and limitations were acknowledged including the difficulty in capturing all different points of view and opinions when there are such a large number of people involved and consulted as well as how this can lead to a slowdown within the whole process and is very expensive. The paper concludes suggesting that a local level monitoring system can help to build local capacity, improve decision-making, reduce conflict between local forest dependents and responsible authorities as well as empower local community members, especially marginalized groups. [less ▲]

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See detailLa localisation : un choix crucial - Winkellokalisatie : een doorslaggevende keuze
Merenne-Schoumaker, Bernadette ULg

in Quel avenir pour la distribution en Belgique? (1992)

The article attempts to compare the advantages and disadvantages of the major types of commercial locations: innercity, suburbs, malls, suburbs and main roads

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See detailLocalisation analysis in masonry using transformation field analysis
Chettah, A.; Mercatoris, Benoît ULg; Sacco, E. et al

in Engineering Fracture Mechanics (2013), 110

Transformation field analysis is used for the multi-scale analysis of cracking localisation in masonry. The evaluation of the corresponding consistent homogenised tangent stiffness required in acoustic ... [more ▼]

Transformation field analysis is used for the multi-scale analysis of cracking localisation in masonry. The evaluation of the corresponding consistent homogenised tangent stiffness required in acoustic tensor-based localisation analysis is derived. The average representative volume element mechanical response is studied for two sets of micro-mechanical material laws for mortar joints, based on damage and damage coupled with plasticity. Localisation analyses for stress proportional loading show that meaningful average localisation orientations are properly detected by the acoustic tensor-based loss of ellipticity criterion. The ability of the procedure to reproduce the failure envelope of running bond masonry subjected to uniform biaxial loads is demonstrated. The energetic aspects for the selection of localised solutions are discussed. It is shown that transformation field analysis yields meaningful homogenised localisation results, thereby allowing envisioning its use in nested multi-scale computations. © 2013 Elsevier Ltd. [less ▲]

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See detailLocalisation de la laminine, fibronectine, de la E-cadhérine et des intégrines dans l’endomètre et l’endométriose
BELIARD, Aude ULg; Donnez, J; Nisolle, Michelle ULg et al

in Reproduction Humaine et Hormones (1998), 2

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See detailLocalisation des activités
Devillet, Guénaël ULg; Kessler, Laurent; Klinkenberg, Anne-Catherine et al

Report (2001)

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See detailLocalisation des centres de radiothérapie : une analyse géographique exploratoire pour la Belgique
COTTEELS, C.; PEETERS, D.; COUCKE, Philippe ULg et al

in Cancer Radiotherapie (2012), 16(7), 604612

Purpose The distance between the patient's home and a radiotherapy department may represent a hurdle for the patient and influence treatment choice. Therefore, it is necessary to check whether the ... [more ▼]

Purpose The distance between the patient's home and a radiotherapy department may represent a hurdle for the patient and influence treatment choice. Therefore, it is necessary to check whether the geographical distribution of radiotherapy centers is in accordance with cancer incidence, taking also into account the cost of travelling to the radiotherapy department. The objective of this study is double; first, to map the current locations of radiotherapy centers across the country and second, to evaluate the observed spatial disparities with appropriate tools. Materials and methods A model of operational research (P-median) is used to suggest the optimal locations and allocations and to compare them with the current situation. This is an exploratory study with simple inputs. It helps to better understand the current geographical distribution of radiotherapy centers in Belgium as well as its possible limitations. Results–conclusion It appears that the current situation is on the average acceptable in terms of accessibility to the service and that the method presents huge potentialities for decision making so as to yield a spatial system that is both efficient and equitable. [less ▲]

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See detailLa localisation des grandes enseignes commerciales. Quelques observations à partir du cas de la Belgique
Merenne-Schoumaker, Bernadette ULg

in Barata Salgueiro Teresa (Ed.) Commerce, aménagement et urbanisme commercial- Public Policy and Urban Reatil Planning (1992)

Behavior analysis of location of large commercial firms initially for the case of Belgium

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See detailLa localisation des grandes zones logistiques
Merenne-Schoumaker, Bernadette ULg

in Bulletin de la Société Géographique de Liège (2007), (49), 31-40

The growth of logistics has recently fathered many new zones of specialized activities, called most of the times parks or logistic platforms. The objective of the article consists in understanding their ... [more ▼]

The growth of logistics has recently fathered many new zones of specialized activities, called most of the times parks or logistic platforms. The objective of the article consists in understanding their development and in identifying the logics of location. For this purpose, we have first tried to identify better the domain of activities: types of logistics, carried out operations, concerned sectors, concerned operators... Afterwards, on the basis of data mostly coming from professional circles, we have attempted to identify the factors and constraints of the new zones location, and to specify the mechanisms of the new real estate business linked to those zones, our goal consisting in bringing out the main principles of location on the scale of the countries, regions and sites choices. In the light of this first analysis, the logic seems pretty specific and takes place undoubtedly between the logic of industries and services. [less ▲]

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See detailLa localisation des industries. Enjeux et dynamiques
Merenne-Schoumaker, Bernadette ULg

Book published by PUR - 3e édition corrigée et mise à jour (2011)

Cinquième édition (deux chez Nathan Université et trois aux PUR) d'un manuel universitaire consacré à la Localisation des industries dont l'objectif est de chercher à expliquer les enjeux et les ... [more ▼]

Cinquième édition (deux chez Nathan Université et trois aux PUR) d'un manuel universitaire consacré à la Localisation des industries dont l'objectif est de chercher à expliquer les enjeux et les dynamiques au coeur des mutations industrielles en combinant les dimensions spatiales et temporelles et en articulant des démarches empiriques et théoriques. Quatre parties : Industrie et espace géographique; Composantes et mécanismes des changements; Dynamiques spatiales à quatre échelles et Logiques de localisation. Cette nouvelle édition comprend de nouveaux développements sur les liens entre industries et développement durable et sur l'industrialisation des pays émergents [less ▲]

Detailed reference viewed: 113 (9 ULg)