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See detailDesign and fabrication of a micromachined electrostatically suspended gyroscope
Damrongsak, Badin; Kraft, Michaël ULg; Rajgopal, S. et al

in Proceedings of the Institution of Mechanical Engineers - Part C - Journal of Mechanical Engineering Science (2008), 222(1), 53--63

The current paper describes the design and fabrication of a micromachined electrostatically suspended gyroscope. Electrostatic levitation is employed to suspend the rotor, eliminating the mechanical ... [more ▼]

The current paper describes the design and fabrication of a micromachined electrostatically suspended gyroscope. Electrostatic levitation is employed to suspend the rotor, eliminating the mechanical bearing and thus friction effects between the rotor and the substrate, hence improving long-term stability. The rate of rotation can be measured by detecting the torque-induced displacement of the spinning rotor using capacitive interface circuits. The device structure and its basic operating principle are described, as well as theoretical background and design considerations. The fabrication process of the gyroscope relies on glass/silicon/ glass stack bonding and deep dry etching and is outlined in detail. Initial prototypes realized with this fabrication process are presented and described. [less ▲]

Detailed reference viewed: 13 (0 ULg)
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See detailDesign and Fabrication of a self-aligning gas/liquid micropump.
Schabmueller, CGJ; Koch, M; Kraft, Michael ULg et al

in Proc. SPIE Micromachining and Microfabrication Conference - Microfluid Devices and Systems III (2000)

Detailed reference viewed: 13 (2 ULg)
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See detailDesign and Fabrication of a self-aligning gas/liquid micropump.
Schabmueller, CGJ; Koch, M; Kraft, Michael ULg et al

in Proc. SPIE Micromachining and Microfabrication Conference - Microfluid Devices and Systems III (2000)

Detailed reference viewed: 15 (2 ULg)
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See detailDesign and fabrication of a variable wall thickness two-stage scroll expander to be integrated in a micro-solar power plant
Dickes, Rémi ULg

Master's dissertation (2013)

Improving access to energy in developing countries without exacerbating climate change requires novel technical strategies. MicroCSP power plants using organic Rankine cycles (ORCs) are one example of a ... [more ▼]

Improving access to energy in developing countries without exacerbating climate change requires novel technical strategies. MicroCSP power plants using organic Rankine cycles (ORCs) are one example of a promising approach for meeting this challenge. Specifically, expander development has been identified as a critical component for enhancing the performances of small ORC units. The goal of this project is to develop an optimized two-stage scroll expander to be integrated in a MicroCSP power plant designed to supply remote, off-grid areas. The expansion requirements are firstly defined so as to meet production specifications. Then, employing a deterministic model and a selection process, optimal scroll geometries are chosen for both expansion stages. The deterministic model is executed with Matlab and accounts for the relevant physical phenomena i.e. radial and flank leakages, throttling losses at the intake and exhaust processes, friction between the two scrolls and mechanical losses in the different bearings. A performance enhancement of about 6\% of the isentropic efficiency is predicted in comparison with baseline practice. A CAD model of a single-stage prototype is developed in Solidworks following the main architectural features of a compliant HVAC scroll compressor. This CAD is updated and improved with the optimal scroll geometries and some parts are 3D printed to verify their mechanical assembly. Toolpaths to control CNC machines are generated using the CAM program HSMXpress and the parts constituting the expander prototype are manufactured in a machine shop. In conclusion, the properties of the enhanced scroll expander are evaluated in the context of a typical Micro-CSP plant. A simple steady state model in EES is developed to quantify how three parameters (T_ev, T_cond and eta_exp) influence the power plant overall sunlight to electricity conversion efficiency (a gain of 0.73% is predicted). This project underscores the importance of optimizing the expansion process and identifies further research pathways to progress towards this goal. [less ▲]

Detailed reference viewed: 263 (43 ULg)
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See detailDesign and fabrication of an electrode array sensor for probing the electric potential distribution at the mesoscopic scale in antistatic felts
Boutaayamou, Mohamed ULg; Lemaire, Philippe; Vanderheyden, Benoît ULg et al

in Measurement Science and Technology (2014), 25

We present an original voltage probe design for measuring the electric potential distribution at the mesoscopic scale (i.e., 1 mm–1 cm) in antistatic felts. The felts are composed of a mixture of non ... [more ▼]

We present an original voltage probe design for measuring the electric potential distribution at the mesoscopic scale (i.e., 1 mm–1 cm) in antistatic felts. The felts are composed of a mixture of non-conductive and metallic fibers and exhibit complex nonlinear electric behavior—including possibly nonlinearity and hysteresis effects—which may be due to localized electrical or electromechanical phenomena. The sensor consists of an array of 8 × 9 needle electrodes (phgr 160 µm at the shaft and less than phgr 50 µm toward the apex), which are mechanically maintained at fixed relative positions while their tips are inserted inside the fabric of the sample. The interelectrode distance is 1.5 mm and the overall active area is 12 × 12 mm². The electrical insulation resistance for nearest neighbor pairs of electrodes was found to be larger than 860 GΩ, thus making the sensor suitable for measuring antistatic felts with an electric resistance that typically does not exceed a few GΩ. The sensor was successfully used for measuring the distribution of the electric potential in a polyester fabric subjected to voltages of up to 6.2 kV, and in a sample containing 2% in weight of metallic fibers, demonstrating the presence of irreversible changes in that felt sample (i.e., with conductive fibers) at high voltages. It is concluded that the developed probe voltage is a promising technique that could be used for the assessment of the conduction mechanisms in the antistatic materials at the mesoscopic scale. [less ▲]

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See detailDesign and Implementation of a Distributed Lattice Boltzmann-based Fluid Flow Simulation Tool
Dethier, Gérard ULg

Doctoral thesis (2011)

Lattice Boltzmann-based (LB) simulations are well suited to the simulation of fluid flows in complex structures encountered in chemical engineering like porous media or structured packing used in ... [more ▼]

Lattice Boltzmann-based (LB) simulations are well suited to the simulation of fluid flows in complex structures encountered in chemical engineering like porous media or structured packing used in distillation and reactive distillation columns. These simulations require large amounts of memory (around 10 gigabytes) and would require very long execution times (around 2 years) if executed on a single powerful desktop computer. The execution of LB simulations in a distributed way (for example, using cluster computing) can decrease the execution time and reduces the memory requirements for each computer. Dynamic Heterogeneous Clusters (DHC) is a class of clusters involving computers inter-connected by a local area network; these computers are potentially unreliable and do not share the same architecture, operating system, computational power, etc. However, DHCs are easy to setup and extend, and are made of affordable computers. The design and development of a software system which organizes large scale DHCs in an efficient, scalable and robust way for implementing very large scale LB simulations is challenging. In order to avoid that some computers are overloaded and slow down the overall execution, the heterogeneity of computational power should be taken into account. In addition, the failure of one or several computers during the execution of a simulation should not prevent its completion. In the context of this thesis, a simulation tool called LaBoGrid was designed. It uses existing static load balancing tools and implements an original dynamic load balancing method in order to distribute the simulation in a way that minimizes its execution time. In addition, a distributed and scalable fault-tolerance mechanism based on the regular saving of simulation’s state is proposed. Finally, LaBoGrid is based on a distributed master-slave model that is robust and potentially scalable. [less ▲]

Detailed reference viewed: 333 (56 ULg)
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See detailDesign and implementation of a MASH2-0 Electromechanical Sigma-Delta Modulator for capacitive MEMS sensors using dual quantization method
Almutairi, Bader; Alsheri, Ali; Kraft, Michael ULg

in Journal of Microelectromechanical Systems (2015)

In this paper, a new control structure based on the dual quantization technique is presented for an electromechanical sigma–delta modulator (EM-SD M) applied to a microelectromechanical system (MEMS ... [more ▼]

In this paper, a new control structure based on the dual quantization technique is presented for an electromechanical sigma–delta modulator (EM-SD M) applied to a microelectromechanical system (MEMS) accelerometer. The modulator adopts a 2-0 multistage noise shaping structure (MASH2-0), taking the advantage of the intrinsic linearity of single-bit quantization and the reduced quantization error of multibit quantization in a single modulator. The sensor system is studied by the system-level modeling and the hardware implementation based on the field-programmable gate array technology. The study shows that, MASH2-0 shares the benefits of a MASH2-2 architecture of having an inherent stability, a high overload input level, and a high dynamic range compared with single-loop EM-SD M. However, the MASH2-0 architecture benefits from a considerably simpler implementation, while achieving a higher dynamic range and a higher signal-to-noise ratio compared with a MASH2-2 and a fourth-order single-loop SDM architecture. A capacitive MEMS accelerometer was designed and employed with this control system. Within a bandwidth of 1 kHz, the sensor achieved a noise floor level of −130 dB and a bias instability as low as 20 μg at an integration time of 40 s. Simulation estimated a full scale of ±20 g acceleration. The investigation confirms the concept of the MASH2-0 structure and shows its potential as a closed-loop interface for high-performance capacitive MEMS accelerometers. [less ▲]

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See detailDesign and implementation of a T impedance matching network for the radiocommunication subsystem aboard the OUFTI-1 nanosatellite
Boutaayamou, Mohamed ULg; Crosset, Nicolas ULg; Werner, Xavier ULg et al

in Proceedings of the URSI Forum 2014 (2014, November 18)

We describe how we handled an unexpected impedance matching issue on the receiver side (at UHF) of the radiocommunication system aboard the OUFTI-1 nanosatellite of the University of Liège. Our approach ... [more ▼]

We describe how we handled an unexpected impedance matching issue on the receiver side (at UHF) of the radiocommunication system aboard the OUFTI-1 nanosatellite of the University of Liège. Our approach relied on a combination of novel analytical developments combined with experimentation. [less ▲]

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See detailDesign and implementation of a ‘physical activity day’ for overweight and obese youth
Cloes, Marc ULg; DEWANDRE, Anne-Cécile ULg; LEBRETHON, Marie-Christine ULg et al

in Tijdschrift van de Belgische Kinderarts = Journal du Pédiatre Belge (2015, March), 17(1),

This study aimed to analyze the development and implementation of an adapted physical activity day expected to underline to overweight/obese youth the role of PA and hw they could be more active in their ... [more ▼]

This study aimed to analyze the development and implementation of an adapted physical activity day expected to underline to overweight/obese youth the role of PA and hw they could be more active in their daily life. [less ▲]

Detailed reference viewed: 47 (8 ULg)
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See detailDesign and implementation of an advanced state estimation software
Van Cutsem, Thierry ULg; Mili, Lamine; Vandeloise, Philippe

in Proc. IFAC Symposium on Power Systems and Power Plant control (1986)

Detailed reference viewed: 23 (0 ULg)
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See detailDesign and implementation of an optimized double closed-loop control system for MEMS vibratory gyroscope
Chen, Fang; Yuan, Weizheng; Chang, Honglong et al

in IEEE Sensors Journal (2014), 14(1), 184--196

Detailed reference viewed: 20 (0 ULg)
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See detailDesign and integrity assessment of high strength tubular structures for extreme loading conditions
Bursi, Oreste; Kumar, Anil; Demofonti, Giuseppe et al

Book published by European Commission (2012)

High Strength Steel (HSS) characterized by yield strength ranging between 500MPa to 700MPa has been available for many years. However, its use in onshore engineering is quite restrictive. Reasons were ... [more ▼]

High Strength Steel (HSS) characterized by yield strength ranging between 500MPa to 700MPa has been available for many years. However, its use in onshore engineering is quite restrictive. Reasons were threefold: i) Eurocodes covered steels with yield strength up to 460MPa; ii) higher costs than regular steel; iii) lack of conceptual design with HSS. Nonetheless very recently, there has been a growing trend for the use of HSS in tubular structures thanks to Eurocode 3 Part 1-12 (2006), that extended its scope to steel grades up to S690/S700MC. Along this line, the HITUBES project intended to develop performance-based designs and assessment procedures to make full use of HSS tubes up to S700MC for structures subject also to extreme repeated loads; in fact Eurocode 3 Part 1-12 imposes many limitations at the material, structural and design level. The ambitious targets are to increase the performance of tubular structures, reduce weights, construction and operating costs. The project covered the period 01/07/2008-31/12/2011, and main research work focussed on several aspects listed herein: literature survey; selection of finite element-based and identification dynamic analysis codes; selection of realistic Case Studies and FE analysis for the evaluation of actions and stresses; structural identification and health monitoring of a cable-stay and arch footbridges; tests planning and execution including welding procedure specifications; simulations of welded and bolted connections under monotonic, low-cycle and high-cycle fatigue loadings; simulation of Case studies and reliability analysis for quantification of realistic performance scenarios; SWOT analysis and monitoring of project activities. [less ▲]

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See detailDesign and methodology of the phase 3 trials for the clinical development of strontium ranelate in the treatment of women with postmenopausal osteoporosis
Meunier, P. J.; Reginster, Jean-Yves ULg

in Osteoporosis International (2003), 14(Suppl. 3), 66-76

The phase 3 program for strontium ranelate, a new oral agent in the treatment of women with postmenopausal osteoporosis, was aimed to assess the efficacy and safety of the daily oral dose of 2 g. This ... [more ▼]

The phase 3 program for strontium ranelate, a new oral agent in the treatment of women with postmenopausal osteoporosis, was aimed to assess the efficacy and safety of the daily oral dose of 2 g. This program was conducted in 12 countries, involved 75 centers, and was structured in 3 studies: FIRST (Fracture International Run-in for Strontium ranelate Trial), SOTI (Spinal Osteoporosis Therapeutic Intervention study) and TROPOS (TReatment Of Peripheral OSteoporosis). FIRST, a run-in open study, was designed to start the normalization of the calcium and vitamin D status of the patients, check all entry criteria, and ensure inclusion of a sufficient number of well-motivated patients in either one of the two therapeutic intervention protocols, SOTI or TROPOS: FIRST included 9,196 patients. SOTI and TROPOS were prospective, randomized, double-blind clinical trials comparing, in two parallel groups, the daily oral dose of 2 g of strontium ranelate with placebo, the patients of both groups receiving calcium and vitamin D according to their own deficiencies. The main objective of SOTI and TROPOS was to demonstrate a reduction in the incidence of postmenopausal women experiencing a new osteoporotic fracture (vertebral fracture in SOTI and nonvertebral fracture in TROPOS) over a 3-year treatment period, the total duration of the studies being 5 years. SOTI included 1,649 women with at least one osteoporotic vertebral fracture at inclusion and a lumbar BMD less than or equal to 0.840 g/cm(2). TROPOS included 5,091 women with a femoral neck BMD less than or equal to 0.600 g/cm(2). The phase 3 program for the clinical development of strontium ranelate in women with postmenopausal osteoporosis is a long-term program with the main statistical analysis after 3 years of treatment. Its aim is to demonstrate the effect of strontium ranelate on the axial and appendicular skeleton as well as its tolerability in osteoporotic patients with replete calcium and vitamin D stores. [less ▲]

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See detailDesign and modeling of new PAF antagonists - 1,4-bis-(3',4',5'-trimethoxybenzoyl)-2-substituted carbonyloxymethyl piperazines
Heymans, Françoise; Lamouri, Aazdine; Batt, Jean-Pierre et al

in Journal of Lipid Mediators and Cell Signalling (1994), 10(1-2), 153-154

Detailed reference viewed: 4 (1 ULg)
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See detailDesign and modeling of new platelet-activating factor antagonists.2. Synthesis and biological activity of 1,4-bis-(3',4',5'-trimethoxybenzoyl)-2-alkyl and 2-alkoxymethylpiperazines
Tavet, Fabrice; Lamouri, Aazdine; Heymans, Françoise et al

in Journal of Lipid Mediators and Cell Signalling (1996), 15

Detailed reference viewed: 36 (1 ULg)
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See detailDesign and modeling of new platelet-activating factor antagonists.3. Relative importance of hydrophobicity and electronic distribution in piperazinic series
Heymans, Françoise; Dive, Georges ULg; Lamouri, Aazdine et al

in Journal of Lipid Mediators and Cell Signalling (1996), 15(2), 161-173

Detailed reference viewed: 11 (1 ULg)
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See detailDesign and modeling of new platelet-activating-factor antagonists.1. Synthesis and biological activity of 1,4-bis(3',4',5'-trimethoxybenzoyl)-2-[[(substituted carbonyl and carbamoyl)oxy]methyl]piperazines
Lamouri, Aazdine; Heymans, Françoise; Tavet, Fabrice et al

in Journal of Medicinal Chemistry (1993), 36(8), 990-1000

Detailed reference viewed: 12 (1 ULg)
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See detailDesign and modelisation of a straylight facility for space optical instrument
Mazy, Emmanuel ULg; Stockman, Yvan ULg; Hellin, Marie-Laure ULg

in SPIE (Ed.) 2012 Optical system Design (in press)

In the framework of instrument calibration, straylight issues are a critical aspect that can deteriorate the optical performances of instrument. To cope with this, a new facility is designed dedicated for ... [more ▼]

In the framework of instrument calibration, straylight issues are a critical aspect that can deteriorate the optical performances of instrument. To cope with this, a new facility is designed dedicated for in-field and far field straylight characterization: up to 10-8 for in-field and up to 10-10 for far field straylight in the visible to NIR spectral ranges. Moreover, from previous straylight test performed at CSL, vacuum conditions are needed for reaching the 10-10 rejection requirement mainly to avoid air/dust diffusion. The major constrains are to design a straylight facility either for in-field and out-field straylight measurements. That requires high dynamic range at source level and a high radiance point source allowing small diverging collimated beam. Moreover, the straylight facility has to be implemented into a limited envelope and has to be built with vacuum compatible materials and black coating. As checking the facility performance requires an instrument better than the facility itself, that is no easy to find, so that the performances have been estimated through a modelisation into a non sequential optical software. This modelisation is based on CAD importation of mechanical design, on BRDF characteristics of black coating and on statistical averaging of ray tracing at instrument entrance. [less ▲]

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See detailDesign and modelisation of ASPIICS optics
Galy, Camille ULg; Fineschi, S.; Galano, D. et al

in Proc. SPIE Volume 9604 Solar Physics and Space Weather Instrumentation VI (2015, September 21)

In the framework of development of ASPIICS (Association of Spacecraft for Polarimetric and Imaging Investigation of the Corona of the Sun), the Centre Spatial de Liege is responsible of the optical design ... [more ▼]

In the framework of development of ASPIICS (Association of Spacecraft for Polarimetric and Imaging Investigation of the Corona of the Sun), the Centre Spatial de Liege is responsible of the optical design of the coronagraph and the optics will be manufactured by TOPTEC. The particularity of this coronagraph is to have an external occulter located 150 m ahead of the first imaging lens. This external occulter is re-imaged on an internal occulter which function is - as in a classical externally occulted Lyot coronagraph - to block the sun light diffracted by the external occulter and to reduce the straylight on the detector. The selection of this configuration is driven by the requirement to observe the corona as close as possible to the solar limb (i.e. 1 RSun) without imaging the limb itself. A requirement of 1.08 RSun is specified at optical design level to grant 1.2 Rsun at instrument level. The coronograph instrument is designed to have a field of view of 1.6° x 1.6° with a resolution of less than 6 arcsec. Its performances are limited by diffraction in a 530 – 590 nm wavelength range. This paper presents the optical design and demonstrates that by design the requirements are fulfilled within the misalignment, manufacturing and thermo-elastic error contributions. [less ▲]

Detailed reference viewed: 50 (28 ULg)