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See detailAn inventory of emerging innovation project in belgium, Typical and traditional products: rural effect and agro-industrial problems, Parma – Italy ,
Van Huylenbroeck, I.; Verhaegen, Ingrid; Collet, Eric et al

in Proceeding of the 52nnd Seminar of the EAAE (1998)

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See detailInventory routing for perishable products
Rezaei Sadrabadi, Mahmood ULg

Doctoral thesis (2016)

We explore three problems in this thesis and develop solution methods for each problem. First, an inventory routing problem for a perishable product with stochastic demands is considered and different ... [more ▼]

We explore three problems in this thesis and develop solution methods for each problem. First, an inventory routing problem for a perishable product with stochastic demands is considered and different approximate solution methods are developed to solve. Based on computational experiments, the solution methods are compared in terms of average profit, service level, and actual freshness. The impact of relevant parameters on the performance of the solution methods is investigated. Managerial insights are drawn by analyzing the impact of shelf life and store capacity on the profit. The value of considering uncertainty and the value of accessing full information are measured. The computational results highlight that a simple ordering policy can often replace a more sophisticated solution method, while preserving the same efficacy. Second, we introduce a vehicle routing problem (VRP) where a set of stores places deterministic orders to a logistics service provider (LSP) for two successive periods. Deliveries requested in each period can be shifted by the LSP to the other period, possibly with modified quantities. The LSP incurs a penalty for any diversion from the initial delivery period. The data regarding shifted delivery quantities and penalties are provided by the stores. From the perspective of the LSP, diversions could be beneficial if savings in the routing costs outweigh the penalties. In this work, we introduce a new two-period VRP model where the LSP seeks to improve its total cost, compared to solving two independent VRPs with fixed delivery periods, by allowing deliveries to be shifted. We solve this model to optimality by an efficient branch-and-price algorithm implementing several cutting-edge techniques. We draw algorithmic and managerial insights based on our test instances. Third, a two-period VRP is considered where the orders placed by stores for each period can be partially shifted to the other period, given that the sum of the delivery quantities in two periods to each customer is fixed. A linear penalization of delivery shifts is assumed based on the quantity shifted. We represent two mixed integer linear programming (MILP) formulations for the problem. A column-row generation algorithm to solve the LP-relaxation of the first formulation is developed. To solve the LP-relaxation of the second formulation, we develop a column generation algorithm. Details of two label-setting algorithms to solve the pricing problems of the column-row generation and column generation algorithms are discussed. Numerical results can be compared with a similar model in which only full delivery shifts are allowed. [less ▲]

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See detailThe inventory-routing problem of returnable transport items with time windows and simultaneous pickup and delivery in closed-loop supply chains
Iassinovskaia, Galina; Limbourg, Sabine ULg; RIANE, Fouad

in International Journal of Production Economics (2016), (183), 570-582

Reducing environmental impact, related regulations and potential for operational benefits are the main reasons why companies share their returnable transport items (RTIs) among the different partners of a ... [more ▼]

Reducing environmental impact, related regulations and potential for operational benefits are the main reasons why companies share their returnable transport items (RTIs) among the different partners of a closed-loop supply chain. In this paper, we consider a producer, located at a depot, who has to distribute his products packed in RTIs to a set of customers. Customers define a time window wherein the service can begin. The producer is also in charge of the collection of empty RTIs for reuse in the next production cycle. Each partner has a storage area composed of both empty and loaded RTI stock, as characterized by initial levels and maximum storage capacity. As deliveries and returns are performed by a homogeneous fleet of vehicles that can carry simultaneously empty and loaded RTIs, this research addresses a pickup and delivery inventory-routing problem within time windows (PDIRPTW) over a planning horizon. A mixed-integer linear program is developed and tested on small-scale instances. To handle more realistic large-scale problems, a cluster first-route second matheuristic is proposed. [less ▲]

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See detailInventory-routing problem with pickups and deliveries of RTI in closed-loop supply chain
Iassinovskaia, Galina; Limbourg, Sabine ULg; Riane, Fouad

Conference (2014, July 17)

Reducing environmental impact, related regulations and potential for operational benefits are the main reasons why companies share their Returnable Transport Items (RTIs) among different partners of a ... [more ▼]

Reducing environmental impact, related regulations and potential for operational benefits are the main reasons why companies share their Returnable Transport Items (RTIs) among different partners of a closed-loop supply chain. This research deals with an inventory-routing problem with pickups and deliveries of RTIs. A mixed-integer linear program is developed and tested on small instances. To handle realistic large size problems, a clustering algorithm is coupled with a simulation model. This hybrid heuristic allows assessing the benefits of information and RTIs sharing among partners. [less ▲]

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See detailInventorying urban areas with Very High Resolution Satellite Images
Van de Voorde, Tim; Binard, Marc ULg; Op ’t Eyndt, Tom

in Ramon, J.; Ruiz, M.; Gold, M. (Eds.) Procredings of the 5th AGILE Conference on Geographical Information Science (2002)

Prior to the commercial availability of Very High Resolution (VHR) satellite imagery, the applicability of Earth Observation data in the urban planning sector was very limited. The spatial resolution of ... [more ▼]

Prior to the commercial availability of Very High Resolution (VHR) satellite imagery, the applicability of Earth Observation data in the urban planning sector was very limited. The spatial resolution of the imagery, supplied by platforms like Landsat TM and SPOT HRV, was too coarse to be of real practical use to urban planners and their applications. Satellite images of urban or sub-urban areas are characterized by large radiometric variations due to the small size and the diversity of the objects. This in turn causes a radiometric contamination between neighbouring pixels which renders object recognition nearly impossible. Satellite images with a higher resolution might alleviate this problem. The dawn of the VHR era was thus anticipated with great aspiration by urban remote sensing researchers. In the framework of a DWTC/OSTC Telsat 4 pilot project we proposed a methodology to employ IKONOS-21 imagery to develop an inventory of built-up, and un-built areas in Belgium’s Flemish region. Such an inventory can be of use to regional planning agencies that are responsible for the implementation of the government’s planning policies. In Flanders, AROHM (Administration of Spatial Planning, Housing, Monuments and landscapes) records, monitors, and evaluates the built-up areas. To do this, they need an extensive data input from the communities, which requires a lot of time and effort. A reliable and swift technique, based on earth observation data, and applicable for each residential area in Flanders, would be of great value to them. Not only would it allow them to make swift assessments more frequently, they could also double-check incoming data from the communities. The aforementioned project consisted of three parts: the visual interpretation of two study areas (Hasselt and Ghent), the automatic classification of these areas using both Maximum Likelihood and Neural Network classifiers, and the development of GIS procedures to transform the classified images into thematic maps like, for instance, a map of building densities. [less ▲]

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See detailInverse analysis in geotechnics: soil parameter identification by genetic algorithm
Levasseur, Séverine ULg; Malécot, Yann; Boulon, Marc et al

in 8th. World Congress on Computational Mechanics (WCCM8) & 5th. European Congress on Computational Methods in Applied Sciences and Engineering (ECCOMAS 2008) (2008)

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See detailInverse analysis on in situ geotechnical measurement using a genetic algorithm
Malécot, Yann; Levasseur, Séverine ULg; Boulon, Marc et al

in Pande, G. N.; Pietruszczak, S. (Eds.) Numerical Models in Geomechanics (2004)

This paper is dedicated to the identification of constitutive parameters of the Mohr-Coulomb constitutive model from in situ measurements. A general definition of an objective function is proposed. A ... [more ▼]

This paper is dedicated to the identification of constitutive parameters of the Mohr-Coulomb constitutive model from in situ measurements. A general definition of an objective function is proposed. A direct approach of inverse analysis is used to identify the shear modulus and the friction angle in four different situations. The first two examples deal with a “numerical” and with a real pressuremeter curve. A difficult convergence and a strong non unicity of solution is observed, which is classical in inverse analysis (ill posed problems). In a second stage, the horizontal displacements related to two excavation problems are used for identifying the two mechanical parameters. A clear minimum of the objective function is detected, giving a unique solution. The reasons of these differences are discussed and some ways of improving the interpretation of the pressuremeter test results are proposed. [less ▲]

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See detailInverse analysis techniques for parameter identification in simulation of excavation support systems
Rechea, Cecilia; Levasseur, Séverine ULg; Finno, Richard J

in Computers & Geotechnics (2008), 35(3), 331-345

Two numerical procedures are described that quantitatively identify a set of constitutive parameters that best represents observed ground movement data associated with deep excavations in urban ... [more ▼]

Two numerical procedures are described that quantitatively identify a set of constitutive parameters that best represents observed ground movement data associated with deep excavations in urban environments. This inverse problem is solved by minimizing an objective (or error) function of the weighted least-squares type that contains the difference between observed and calculated ground displacements. The problem is solved with two different minimization algorithms, one based on a gradient method and the other on a genetic algorithm. The objective function is shown to be smooth with a unique solution. Both methods are applied to lateral movements from synthetic and real excavations to illustrate various aspects of the implementation of the methods. The advantages and disadvantages of each method applied to excavation problems are discussed. [less ▲]

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See detailInverse control of prolactin and growth hormone gene expression: effect of thyroliberin on transcription and RNA stabilization
Laverriere, J. N.; Morin, A.; Tixier-Vidal, A. et al

in EMBO Journal (1983), 2(9), 1493-9

The hypothalamic tripeptide thyroliberin (TRH) regulates prolactin (PRL) and growth hormone (GH) synthesis inversely by modulating the levels of their specific mRNA. Changes in mRNA levels could involve ... [more ▼]

The hypothalamic tripeptide thyroliberin (TRH) regulates prolactin (PRL) and growth hormone (GH) synthesis inversely by modulating the levels of their specific mRNA. Changes in mRNA levels could involve both transcriptional and posttranscriptional events. To examine further these possibilities, we have investigated the effect of TRH on the biosynthesis and degradation of PRL and GH RNA in a rat pituitary tumor cell line. Newly synthesized PRL and GH RNA sequences were quantified in nuclear and cytoplasmic fractions by hybridization of 3H-labelled RNA to immobilized plasmid DNA containing either PRL or GH cDNA sequences. Steady-state levels of specific RNA were estimated by RNA blot hybridization. The results indicate that TRH increases in a rapid but transient manner the transcription of the PRL gene, and suggest that it does not alter the processing and the transport to the cytoplasm. In contrast, after a lag-time, TRH seems to induce a long-lasting inhibition on GH, as well as on overall gene transcription. Furthermore, we observed an effect of TRH on mRNA stability. TRH significantly increases the half-life of PRL mRNA. Our results also support the hypothesis that TRH decreases the half-life of GH mRNA. Such post-transcriptional action of TRH amplifies and prolongs the regulations exerted at the transcriptional level. [less ▲]

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See detailInverse Design of Compressor and Turbine Blades at Transonic Flow Conditions
Léonard, Olivier ULg; Van den Braembussche, René

in Proceedings of the ASME Turbo Expo 1992 (1992, June)

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See detailInverse dynamics of a flexible 3D robotic arm for a trajectory tracking task
Lismonde, Arthur ULg; Sonneville, Valentin; Bruls, Olivier ULg

Scientific conference (2016, May 30)

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See detailInverse dynamics of parallel kinematic manipulators with flexible links
Guimaraes Bastos Junior, Guaraci ULg; Seifried, Robert; Bruls, Olivier ULg

Conference (2012, May)

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See detailInverse dynamics of serial and parallel underactuated multibody systems using a DAE optimal control approach
Guimaraes Bastos Junior, Guaraci ULg; Seifried, Robert; Bruls, Olivier ULg

in Multibody System Dynamics (2013)

The inverse dynamics analysis of underactuated multibody systems aims at determining the control inputs in order to track a prescribed trajectory. This paper studies the inverse dynamics of non-minimum ... [more ▼]

The inverse dynamics analysis of underactuated multibody systems aims at determining the control inputs in order to track a prescribed trajectory. This paper studies the inverse dynamics of non-minimum phase underactuated multibody systems with serial and parallel planar topology, e.g. for end-effector control of flexible manipulators or manipulators with passive joints. Unlike for minimum phase systems, the inverse dynamics of non-minimum phase systems cannot be solved by adding trajectory constraints (servoconstraints) to the equations of motion and applying a forward time integration. Indeed, the inverse dynamics of a non-minimum phase system is known to be non-causal, which means that the control forces and torques should start before the beginning of the trajectory (preactuation phase) and continue after the end-point is reached (post-actuation phase). The existing stable inversion method roposed for general nonlinear non-minimum phase systems requires to derive explicitly the equations of the internal dynamics and to solve a boundary value problem. This paper proposes an alternative solution strategy which is based on an optimal control approach using a direct transcription method. The method is illustrated for the inverse dynamics of an underactuated serial manipulator with rigid links and four degrees-of-freedom and an underactuated parallel machine. An important advantage of the proposed approach is that it can be applied directly to the standard equations of motion of multibody systems either in ODE or in DAE form. Therefore, it is easier to implement this method in a general purpose simulation software. [less ▲]

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See detailINVERSE DYNAMICS OF UNDERACTUATED MULTIBODY SYSTEMS USING A DAE OPTIMAL CONTROL APPROACH
Guimaraes Bastos Junior, Guaraci ULg; Seifried, Robert; Bruls, Olivier ULg

in Proceedings of the ECCOMAS Thematic Conference (MULTIBODY DYNAMICS) 2011 (2011, July)

The inverse dynamics analysis of underactuated multibody systems aims at determining the control inputs in order to track a prescribed trajectory. This paper studies the inverse dynamics of non-minimum ... [more ▼]

The inverse dynamics analysis of underactuated multibody systems aims at determining the control inputs in order to track a prescribed trajectory. This paper studies the inverse dynamics of non-minimum phase underactuated multibody systems, e.g. for end-effector control of flexible manipulators or manipulators with passive joints. Unlike for minimum phase systems, the inverse dynamics of non-minimum phase systems cannot be solved by adding trajectory constraints to the equations of motion and by applying a forward time integration. Indeed, the inverse dynamics of a non-minimum phase system is known to be non-causal, which means that the control forces and torques should start before the beginning of the trajectory (pre-actuation phase) and continue after the end-point is reached (post-actuation phase). The existing stable inversion method proposed for general nonlinear non-minimum phase systems requires to derive explicitly the equations of the internal dynamics and to solve a boundary value problem. This paper proposes an alternative solution strategy which is based on an optimal control approach. The method is illustrated for the inverse dynamics of a planar underactuated manipulator with rigid links and four degrees-of-freedom. An important advantage of the proposed approach is that it can be applied directly to the standard equations of motion of multibody systems either in ODE or in DAE form. Therefore, it is easier to implement this method in a general purpose simulation software. [less ▲]

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See detailInverse Estimates of Anthropogenic Carbon Dioxide From Ocean Interior Carbon Measurements and Ocean General Circulation Models
Mikaloff Fletcher, S. E.; Gruber, N. P.; Jacobson, A. R. et al

Conference (2003, December)

The ocean is an important sink for atmospheric carbon dioxide, and the exchange of carbon dioxide between the atmosphere and ocean plays a critical role in determining the spatial distribution of ... [more ▼]

The ocean is an important sink for atmospheric carbon dioxide, and the exchange of carbon dioxide between the atmosphere and ocean plays a critical role in determining the spatial distribution of atmospheric carbon dioxide. However, there is still a great deal of uncertainty in both magnitude and regional patterns of anthropogenic uptake associated with estimates of oceanic carbon fluxes. Using a recently developed technique, exchange of anthropogenic carbon dioxide across the air-sea interface have been estimated from observations of dissolved inorganic carbon and nutrient concentrations and an Ocean General Circulation Model (OGCM) using a Green's function inverse modeling technique. Previous sensitivity studies have shown that model circulation error is an important source of error in the ocean inversion. In order to address the role of ocean circulation biases, inverse estimates of anthropogenic carbon air-sea gas exchange are presented using basis functions from a suite of seven different OGCM's. The robustness of the ocean inversion will be quantified and the effects of differences between approaches to modeling ocean circulation on the ocean carbon cycle will be explored. These results will be discussed in the context of recent atmospheric inverse estimates. [less ▲]

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See detailInverse estimates of anthropogenic CO2 uptake, transport, and storage by the ocean
Mikaloff Fletcher, S. E.; Gruber, N.; Jacobson, A. R. et al

in Global Biogeochemical Cycles (2006), 20(2),

[1] Regional air-sea fluxes of anthropogenic CO2 are estimated using a Green's function inversion method that combines data-based estimates of anthropogenic CO2 in the ocean with information about ocean ... [more ▼]

[1] Regional air-sea fluxes of anthropogenic CO2 are estimated using a Green's function inversion method that combines data-based estimates of anthropogenic CO2 in the ocean with information about ocean transport and mixing from a suite of Ocean General Circulation Models (OGCMs). In order to quantify the uncertainty associated with the estimated fluxes owing to modeled transport and errors in the data, we employ 10 OGCMs and three scenarios representing biases in the data-based anthropogenic CO2 estimates. On the basis of the prescribed anthropogenic CO2 storage, we find a global uptake of 2.2 +/- 0.25 Pg C yr(-1), scaled to 1995. This error estimate represents the standard deviation of the models weighted by a CFC-based model skill score, which reduces the error range and emphasizes those models that have been shown to reproduce observed tracer concentrations most accurately. The greatest anthropogenic CO2 uptake occurs in the Southern Ocean and in the tropics. The flux estimates imply vigorous northward transport in the Southern Hemisphere, northward cross-equatorial transport, and equatorward transport at high northern latitudes. Compared with forward simulations, we find substantially more uptake in the Southern Ocean, less uptake in the Pacific Ocean, and less global uptake. The large-scale spatial pattern of the estimated flux is generally insensitive to possible biases in the data and the models employed. However, the global uptake scales approximately linearly with changes in the global anthropogenic CO2 inventory. Considerable uncertainties remain in some regions, particularly the Southern Ocean. [less ▲]

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See detailInverse estimates of the oceanic sources and sinks of natural CO2 and the implied oceanic carbon transport
Mikaloff Fletcher, S. E.; Gruber, N.; Jacobson, A. R. et al

in Global Biogeochemical Cycles (2007), 21(1),

We use an inverse method to estimate the global-scale pattern of the air-sea flux of natural CO2, i.e., the component of the CO2 flux due to the natural carbon cycle that already existed in preindustrial ... [more ▼]

We use an inverse method to estimate the global-scale pattern of the air-sea flux of natural CO2, i.e., the component of the CO2 flux due to the natural carbon cycle that already existed in preindustrial times, on the basis of ocean interior observations of dissolved inorganic carbon (DIC) and other tracers, from which we estimate Delta C-gasex, i.e., the component of the observed DIC that is due to the gas exchange of natural CO2. We employ a suite of 10 different Ocean General Circulation Models (OGCMs) to quantify the error arising from uncertainties in the modeled transport required to link the interior ocean observations to the surface fluxes. The results from the contributing OGCMs are weighted using a model skill score based on a comparison of each model's simulated natural radiocarbon with observations. We find a pattern of air-sea flux of natural CO2 characterized by outgassing in the Southern Ocean between 44 degrees S and 59 degrees S, vigorous uptake at midlatitudes of both hemispheres, and strong outgassing in the tropics. In the Northern Hemisphere and the tropics, the inverse estimates generally agree closely with the natural CO2 flux results from forward simulations of coupled OGCM-biogeochemistry models undertaken as part of the second phase of the Ocean Carbon Model Intercomparison Project (OCMIP-2). The OCMIP-2 simulations find far less air-sea exchange than the inversion south of 20 degrees S, but more recent forward OGCM studies are in better agreement with the inverse estimates in the Southern Hemisphere. The strong source and sink pattern south of 20 degrees S was not apparent in an earlier inversion study, because the choice of region boundaries led to a partial cancellation of the sources and sinks. We show that the inversely estimated flux pattern is clearly traceable to gradients in the observed Delta C-gasex, and that it is relatively insensitive to the choice of OGCM or potential biases in Delta C-gasex. Our inverse estimates imply a southward interhemispheric transport of 0.31 +/- 0.02 Pg C yr(-1), most of which occurs in the Atlantic. This is considerably smaller than the 1 Pg C yr(-1) of Northern Hemisphere uptake that has been inferred from atmospheric CO2 observations during the 1980s and 1990s, which supports the hypothesis of a Northern Hemisphere terrestrial sink. [less ▲]

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See detailInverse Expression of Two Laminin Binding Proteins, 67lr and Galectin-3, Correlates with the Invasive Phenotype of Trophoblastic Tissue
van den Brule, F. A.; Price, J.; Sobel, M. E. et al

in Biochemical and Biophysical Research Communications (1994), 201(1), 388-93

Tumor invasion of host tissues and trophoblastic penetration of the endometrium share common biological features. Both processes involve the invasion of basement membranes, an event that is initiated by ... [more ▼]

Tumor invasion of host tissues and trophoblastic penetration of the endometrium share common biological features. Both processes involve the invasion of basement membranes, an event that is initiated by adhesion of cancer or trophoblast cells to basement membrane components and particularly to laminin. Adhesion to this latter glycoprotein is mediated through a variety of cell surface receptors. We have previously shown that the 67 kD Laminin Receptor (67LR) and a 31 kD Human Laminin Binding Protein, recently renamed galectin-3, are inversely modulated as the invasive phenotype of cancer cells progresses, with up regulation of the former, and down regulation of the latter, respectively. In this study, we examined the expression of these two proteins in 27 human trophoblastic specimens at different gestational ages using Northern and Western blot techniques. Expression of the 67LR increased from 7 weeks to a maximum at 12 weeks, when invasion is maximal, and then decreased. Expression of galectin-3 was inversely modulated by the gestational age, with a minimum expression at 12 weeks. Our data demonstrate that invasive trophoblast displays the same pattern of laminin binding proteins expression than invasive cancer cells, and further demonstrates that invasion of the extracellular matrix by trophoblast and cancer cells share common molecular mechanisms. [less ▲]

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