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See detailOptimization of particle packing by analytical and computer simulation approaches
He, Huan ULg; Stroeven, Piet; Stroeven, Martijn et al

in Computers and Concrete (2012), 9(2), 119-131

Optimum packing of aggregate is an important aspect of mixture design, since porosity may be reduced and strength improved. It may also cause a reduction in paste content and is thus of economic relevance ... [more ▼]

Optimum packing of aggregate is an important aspect of mixture design, since porosity may be reduced and strength improved. It may also cause a reduction in paste content and is thus of economic relevance too. Several mathematic packing models have been developed in the literature for optimization of mixture design. However in this study, numerical simulation will be used as the main tool for this purpose. A basic, simple theoretical model is used for approximate assessment of mixture optimization. Calculation and simulation will start from a bimodal mixture that is based on the mono-sized packing experiences. Tri-modal and multi-sized particle packing will then be discussed to find the optimum mixture. This study will demonstrate that computer simulation is a good alternative for mixture design and optimization when appropriate particle shapes are selected. Although primarily focusing on aggregate, optimization of blends of Portland cement and mineral admixtures could basically be approached in a similar way. [less ▲]

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See detailOptimization of PCR Conditions to Amplify Microsatellite Loci in Grapevine (Vitis vinifera L.) Genomic DNA
Ghaffari, Sana; Hasnaoui, Nejib ULg; Ferchichi, Ali

in Revue des Régions Arides (2009), 24

A total of three different primer pairs were optimized for polymerase chain reaction (PCR) to amplify microsatellite loci in total genomic DNA of grapevine (Vitis vinifera L.). Different concentrations of ... [more ▼]

A total of three different primer pairs were optimized for polymerase chain reaction (PCR) to amplify microsatellite loci in total genomic DNA of grapevine (Vitis vinifera L.). Different concentrations of MgCl2, DNA and different regimes of annealing temperature were optimized. For all the primer pairs, 2.5 mM MgCl2 concentration was found optimum. For DNA concentration, 100 ng in the final reaction volume was suitable for good amplification. Annealing temperatures 56°C, 61°C and 58°C were found optimum to amplify with primer pairs VVMD5, scu04vv and VMC8E6, respectively. The other reagents used in PCR and temperature regimes (denaturation and extension temperature) were kept constant. The protocol has been successfully applied producing scorable and clear amplicons in all cultivars studied. These loci can be used to evaluate the genetic variability and cultivar relatedness in autochthonous Vitis vinifera cultivars from Tunisia. [less ▲]

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See detailOptimization of pectin extraction from lemon by-product with acidified date juice using response surface methodology
Masmoudi, Manel; Besbes, Souhail; Chaabouni, Moncef et al

in Carbohydrate Polymers (2008), 74(2), 185-192

Response surface methodology was used to optimize pectin recovery from lemon by-product using an acidified date juice as extraction solution. When enriched in pectin, this latter can be useful for ... [more ▼]

Response surface methodology was used to optimize pectin recovery from lemon by-product using an acidified date juice as extraction solution. When enriched in pectin, this latter can be useful for preparation of date-lemon jelly. The effects of three parameters namely temperature, pH and extraction time, on pectin extraction were Studied. The fitted mathematical model allowed Lis to plot response surfaces as well as isoresponse curves and to determine optimal extraction conditions. Results clearly indicated that the temperature was the main factor influencing the pectin yield which increased with temperature and time or decreasing pH. The selected optimal conditions were: temperature 84.34 degrees C extraction time 3 h 34 min and pH 2.8. These conditions yielded about 11.21%, of pectin versus 10.89% for the predicted value. (C) 2008 Elsevier Ltd. All rights reserved. [less ▲]

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See detailOptimization of poly(2-(dimethylamino)ethyl methacrylate)-co-poly(ethyleneglycol)/DNA complexes designed for cell transfection
Grandfils, Christian ULg; Emonds-Alt, J.

in Minerva Biotecnologica (2005), 17(4), 237-243

Cell transfection relies upon the delivery of genomic material within cells in order to express selected DNA sequences. Non-viral gene delivery systems are preferable over viral vectors for several ... [more ▼]

Cell transfection relies upon the delivery of genomic material within cells in order to express selected DNA sequences. Non-viral gene delivery systems are preferable over viral vectors for several reasons: biosafety, low immunogenicity, higher loading capacity, and easiness of production. Their major drawbacks actually are their limited efficiency in vivo compared to viruses, their cytotoxicity and the fact that they are rapidly cleared up from the bloodstream. The aim of our study was to better characterize the physico-chemical behavior of the polycations based on poly(2-(dimethylamino)ethyl methacrylate)-co-poly(ethyleneglycol) and to control the formulation step to produce the polyelectrolyte complexes. [less ▲]

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See detailOptimization of polymerase chain reaction for detection of Clostridium botulinum type C and D in bovine samples
Prevot, V.; Tweepenninckx, F.; Van Nerom, E. et al

in Zoonoses and Public Health (2007), 54(8), 320-327

Botulism is a rare but serious paralytic illness caused by a nerve toxin that is produced by the bacterium Clostridium botulinum. The economic, medical and alimentary consequences can be catastrophic in ... [more ▼]

Botulism is a rare but serious paralytic illness caused by a nerve toxin that is produced by the bacterium Clostridium botulinum. The economic, medical and alimentary consequences can be catastrophic in case of an epizooty. A polymerase chain reaction (PCR)-based assay was developed for the detection of C. botulinum toxigenic strains type C and D in bovine samples. This assay has proved to be less expensive, faster and simpler to use than the mouse bioassay, the current reference method for diagnosis of C. botulinum toxigenic strains. Three pairs of primers were designed, one for global detection of C. botulinum types C and D (primer pair Y), and two strain-specific pairs specifically designed for types C (primer pair VC) and D (primer pair VD). The PCR amplification conditions were optimized and evaluated on 13 bovine and two duck samples that had been previously tested by the mouse bioassay. In order to assess the impact of sample treatment, both DNA extracted from crude samples and three different enrichment broths (TYG, CMM, CMM followed by TYG) were tested. A 100% sensitivity was observed when samples were enriched for 5 days in CMM followed by 1 day in TYG broth. False-negative results were encountered when C. botulinum was screened for in crude samples. These findings indicate that the current PCR is a reliable method for the detection of C. botulinum toxigenic strains type C and D in bovine samples but only after proper enrichment in CMM and TYG broth. [less ▲]

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See detailOptimization of POP analysis in small sample amounts.
L'Homme, Benjamin ULg; Focant, Jean-François ULg

Conference (2012, October)

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See detailOptimization of Production and Preliminary Characterization of New Exopolysaccharides from Gluconacetobacter hansenii LMG1524
Valepyn, Emmanuel ULg; Berezina, Nathalie; Paquot, Michel ULg

in Advances in Microbiology (2012), 2(4), 488-496

The influence of different carbon and nitrogen sources, of ethanol concentration, the optimal pH, temperature and me-dium composition were evaluated on extracellular polysaccharides (EPS) synthesis and ... [more ▼]

The influence of different carbon and nitrogen sources, of ethanol concentration, the optimal pH, temperature and me-dium composition were evaluated on extracellular polysaccharides (EPS) synthesis and bacterial growth of Gluconace-tobacter hansenii LMG1524, and preliminary characterization of EPS was investigated. The highest EPS yields were obtained using glycerol and ammonium sulphate as carbon and nitrogen sources, respectively. The increase of ethanol concentration in the medium did not influence the EPS synthesis but reduced the bacterial growth. The optimum tem-perature and pH for polysaccharides production were respectively 25 °C and 5; whereas for cell growth were respec-tively 30 °C and 4. The optimal culture medium composition was determined as follows : 10 g/L sucrose, 0.892 g/L (NH4)2SO4, 0.34 g/L NaNO3, 3 mL acetic acid, 1.5 g/L KH2PO4, 1.5 g/L K2HPO4 and 0.6 g/L MgSO4. The polysaccha-rides produced were of 14 and 10 polymerization degrees (DP) and constituted mainly of glucose, galactose and man-nose, in relative percent of 36.36, 33.94 and 22.42, respectively. [less ▲]

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See detailOPTIMIZATION OF RAPESEED MEAL USE FOR FATTENING BULLS
Paquay, R.; Mandiki, S.; Bister, J.-L. et al

Poster (1999)

Two experiments were conducted in order to optimize the incorporation of rapeseed meal (RPM) in diets for growing and fattening of bulls. In a first experiment, the effects of 20% of a low glucosinolate ... [more ▼]

Two experiments were conducted in order to optimize the incorporation of rapeseed meal (RPM) in diets for growing and fattening of bulls. In a first experiment, the effects of 20% of a low glucosinolate (LG) RPM (3.14 mmoles/g DM of concentrate) were studied. In a second experiment, various proportions (0, 10, 20, 34%) of an LG- industrial RPM were tested in order to determine the optimal level in diet of young bulls. Thirty six young Belgian White Blue bulls were used. In the two experiments, large amount of industrial RPM (20 - 34%) did not reduce animal performance whatever the parameter considered (liveweight, daily weight gains, food intake, feed conversion, carcass weight, dressing percentages). Values did not also vary with the level of LG-RPM in the diet. Any effects were observed on the thyroid weight and the size of thyroid follicles. The secretion of thyroid hormones was not affected by RPM except for a decrease (P < 0.05) in the production of thyroxin by thyroid tissue decreased (P < 0.05) with 34% in the diet in Experiment 2. Results concerning plasma testosterone and cortisol contrasted between the two experiments with negative effects or no influence of LG-RPM. It was concluded that levels 20 ≤ A < 34% of double 00 – RPM in diet may be used for fattening bulls but investigations are still needed to outline the long-term effects on steroids and reproductive performance [less ▲]

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See detailOptimization of recombinant human erythropoietin therapy after allogeneic hematopoietic stem cell transplantation.
Baron, Frédéric ULg; Sautois, Brieuc ULg; Baudoux, Etienne ULg et al

in Experimental hematology (2002), 30(6), 546-54

OBJECTIVE: Allogeneic hematopoietic stem cell transplantation (HSCT) is associated with prolonged anemia caused by defective erythropoietin (Epo) production. We enrolled 34 recipients of an allogeneic ... [more ▼]

OBJECTIVE: Allogeneic hematopoietic stem cell transplantation (HSCT) is associated with prolonged anemia caused by defective erythropoietin (Epo) production. We enrolled 34 recipients of an allogeneic HSCT in three consecutive trials to determine the optimal utilization of recombinant human erythropoietin (rhEpo) therapy in this setting. MATERIALS AND METHODS: In the first trial (n = 7), rhEpo 1400 U/kg/week was given from day 1 until a hemoglobin (Hb) level of 10 g/dL was achieved, for a maximum of 60 days. In the second trial, rhEpo 500 U/kg/week was given to achieve Hb levels of 13 to 14 g/dL in 13 anemic patients with fatigue 56 to 1440 days after transplant. In the third trial, rhEpo was scheduled to start on day 35 in 14 patients at a dose of 500 U/kg/week with the aim of achieving Hb levels of 13 to 14 g/dL. RESULTS: In trial 1, erythroid recovery to 1% reticulocytes and red blood cell transfusion independence were faster, but the number of transfusions was not reduced compared to 10 controls. Responses were brisk in trial 2, with transfusion independence achieved after a median of 1 week in 12 of 13 patients, and 2-g Hb increments or Hb values of 11, 12, and 13 g/dL after 6, 7, 10, and 10 weeks, respectively. Transfusions were significantly reduced in the first month of rhEpo therapy. In trial 3, transfusion independence was obtained after a median of 1 week in 13 of 14 patients, and 2-g Hb increments or Hb values of 11, 12, and 13 g/dL after 3, 4, 6, and 8 weeks, respectively. Transfusions rates were considerably reduced compared to the previous month in the same patients or compared to controls undergoing peripheral blood or marrow transplant without rhEpo. CONCLUSIONS: Anemia after allogeneic HSCT is exquisitely sensitive to rhEpo. The benefit is minimal when it is given early post-transplant, as used in all trials to date. However, the rate of major response is greater than 90% when rhEpo is started after day 35. These data provide the basis on which to conduct a prospective, randomized, placebo-controlled trial of rhEpo therapy after allogeneic HSCT. [less ▲]

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See detailOptimization of recombinant root-secreted IgGs production in Arabidopsis thaliana by screening cell wall mutants
Boulanger, Benoit ULg; Périlleux, Claire ULg; Tocquin, Pierre ULg

Poster (2012, April 18)

The production of complex heterologous proteins (e.g. monoclonal antibodies, mAbs) in plants has several advantages animal based systems such as low cost, scalability and limited risk of contamination by ... [more ▼]

The production of complex heterologous proteins (e.g. monoclonal antibodies, mAbs) in plants has several advantages animal based systems such as low cost, scalability and limited risk of contamination by human pathogens. mAbs are glycoproteins that require to be targeted to the plant secretory pathway in order to be properly folded and matured. They are ultimately delivered in the cell wall and are expected to be freely released in the extracellular space and the external medium, which would greatly simplify downstream processing. However, a significant part of plant produced and secreted mAbs remains bound to the cell wall, therefore hindering recovery. In this study, we evaluated the extra-cellular release of root-secreted proteins of wild-type plants and cell wall mutants of Arabidopsis thaliana. Recovered protein were either analyzed by SDS-PAGE for full proteome profiling or by gelatin zymography to reveal the activity of cell wall-bound proteases. The production, secretion and release of recombinant IgG will be eventually studied in transgenic hairy-roots generated from selected mutants. [less ▲]

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See detailOptimization of Service Start Time for an Elementary Shortest Path Problem
Kucukaydin, Hande ULg; Arda, Yasemin ULg; Crama, Yves ULg

Conference (2013, July 08)

We are concerned with an elementary shortest path problem with resource constraints (ESPPRC), where there is a capacitated single vehicle at the depot for serving a set of delivery and backhaul customers ... [more ▼]

We are concerned with an elementary shortest path problem with resource constraints (ESPPRC), where there is a capacitated single vehicle at the depot for serving a set of delivery and backhaul customers with a time window. On a given route, the vehicle can visit a backhaul customer only after all its delivery customers are visited, where the delivery and backhaul customers are considered to be two disjoint sets. Split deliveries and pick-ups are not allowed. In this problem, the vehicle may be assigned to several routes. In addition, the vehicle can begin servicing the customers at any desired time and can be used for at most a fixed amount of time that depends on the shift duration of the assigned driver. Distance and time based variable costs are incurred by serving the customers. Namely, the total cost depends on the total distance traveled and the total amount of time that the vehicle spends by performing the assigned multiple trips. On the other hand, serving a customer yields also a revenue. Therefore, the objective is to determine the optimal service start time of the vehicle from the depot along with the trips to be performed in order to minimize the total of the distance and time costs minus the collected revenues. Such a problem can be faced as the pricing subproblem in branch-and-price algorithms for vehicle routing problems with additional constraints, where the revenues are equivalent to the dual prizes of the visited vertices. In general, ESPPRC can be solved to optimality by using a dynamic programming algorithm. However, since the vehicle can start the service at any point in time and is paid based on the total time during which it has been used, our ESPPRC has to take an infinite number of Pareto-optimal states into account. Therefore, we adapt the well-known dynamic programming algorithm according to this feature and develop piecewise linear time functions that represent total traveling and waiting time depending on a variable start time at the depot. Consequently, we propose appropriate dominance rules to discard feasible paths that cannot lead to the optimal solution. Finally, computational results are presented. [less ▲]

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See detailOptimization of sheet metal forming processes using inverse problems methodology
KLEINERMANN, J. P.; Ponthot, Jean-Philippe ULg; Stainier, Laurent ULg

in Proceedings of COMPLAS 2003, VII International Conference on Computational Plasticity. Fundamentals and Applications (2003, April)

Detailed reference viewed: 18 (3 ULg)
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See detailOptimization of Ship Structure – Minimum Cost
Rigo, Philippe ULg

in Second International Shipbuilding Conference, ISC’98, Krylov Shipbuilding Research Inst. (1998, November)

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See detailOptimization of Shipyard Space Allocation and Scheduling using Heuristic Algorithm
Caprace, Jean-David ULg; Petcu, Cristian ULg; Velarde, Marco et al

in Journal of Marine Science & Technology (2013), 18(3), 404-417

In this paper we describe the development of a tool that allows planners to efficiently and effectively plan space within valuable areas of a shipyard. Traditionally, space is considered as resource ... [more ▼]

In this paper we describe the development of a tool that allows planners to efficiently and effectively plan space within valuable areas of a shipyard. Traditionally, space is considered as resource; however, it is difficult to accurately account for and plan its consumption with the current planning software tools available. The spatial scheduling tool described in this paper can be used by planners to manually or automatically reserve space within the shipyard for construction of large blocks over the entire ship erection period. The software is coupled with a heuristic optimization solver which is inspired by an algorithm used for "3D bin-packing problems". The result is the ability to efficiently generate and compare multiple space allocation alternatives in a reduced time with the ultimate goal of maintaining the critical ship erection schedule. Better solution than manual or semi-automatic allocation of blocks can be obtained through the optimization module. [less ▲]

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See detailOptimization of Stochastic Multi-Period Problems in Transportation
Pironet, Thierry ULg

Scientific conference (2013, July 09)

Présentation générale de la méthodologie et des travaux réalisés dans le domaine de l'optimisation de problèmes multi-périodes en transport dans le cadre de la thèse de Th. Pironet

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See detailOptimization of superconducting critical parameters by tuning the size and magnetization of arrays of magnetic dots
Silhanek, Alejandro ULg; Gillijns, W.; Milosevic, M. V. et al

in Physical Review. B, Condensed Matter and Materials Physics (2007), 76(10),

We investigate the nucleation of superconductivity in an Al film deposited on top of an array of micromagnets with perpendicular anisotropy by dc transport measurements. The absolute control of the ... [more ▼]

We investigate the nucleation of superconductivity in an Al film deposited on top of an array of micromagnets with perpendicular anisotropy by dc transport measurements. The absolute control of the magnetic state of the ferromagnets enabled us to explore the superconductor-normal-metal phase boundary as a function of the magnetization M of the dots. For a given external homogeneous field H, the magnetization of the dots can be tuned in such a way to optimize the field and current compensation in the sample, thus yielding a clear enhancement of the upper critical field H-c2. In addition, we theoretically demonstrate that the critical current I-c for a given temperature could be further enhanced by properly adjusting the size of the magnetic dots. These results are fully corroborated by the Ginzburg-Landau theory as well as analytic estimates. [less ▲]

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See detailOptimization of Surface Allocation using Heuristic Approaches
Langer, Yves; Bay, Maud ULg; Crama, Yves ULg et al

in COMPIT 2005 , Hambourg, Germany (2005, May)

In this paper, we present a scheduling problem that arises in factories producing large building blocks (in our case, a shipyard workshop producing prefabricated keel elements). The factory is divided in ... [more ▼]

In this paper, we present a scheduling problem that arises in factories producing large building blocks (in our case, a shipyard workshop producing prefabricated keel elements). The factory is divided in several equal size areas. The blocks produced in the factory are very large, and, once a building block is placed in the factory, it cannot be moved until all processes on the building block are finished. The blocks cannot overlap. The objective is to maximize the number of building blocks produced in the factory during a certain time window. To solve this problem, we propose heuristics inspired by techniques initially developed for the three-dimensional bin packing problem, e.g. Faroe and al. (2003), since constraints for both problems are quite similar. Starting from an unfeasible solution, where blocks can overlap, a Guided Local Search (GLS) heuristic is used to minimize the sum of total overlap. If a solution with zero overlap is found, then it is a feasible solution; otherwise the block with the biggest overlap is removed and the procedure is restarted. The GLS algorithm has been improved by Fast Local Search (FST) tech- niques in order to speed up convergence to a local minimum. Additionally, neighborhoods are restricted to their smallest size so as to allow their evaluation in polynomial-time. In a last step, we explain the additional real-life issues arising in the industrial application and how firm-specific constraints can be conveniently considered by the model. [less ▲]

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See detailOptimization of Surface Utilization Using Heuristic Approaches
Langer, Yves; Bay, Maud ULg; Crama, Yves ULg et al

in Ship Technology Research = Schiffstechnik (2005), 52(3), 141-147

We present a scheduling problem that arises in factories producing large building blocks. This is a three dimensional bin-packing problem with two spatial dimensions and a time dimension. We propose an ... [more ▼]

We present a scheduling problem that arises in factories producing large building blocks. This is a three dimensional bin-packing problem with two spatial dimensions and a time dimension. We propose an algorithm based on the guided local search heuristic of Faroe and al. (Informs Journal of Computing,vol.15, 2003). The algorithm is especially developped to consider real-life issues. Finally the algorithm is applied on an industrial problem and shows excellent performances in speed and quality of the solution. [less ▲]

Detailed reference viewed: 112 (30 ULg)