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Introduction
Publications
Publications (89)
A new tracking detector will be installed as part of the Phase-2 upgrade of the CMS detector for the high-luminosity LHC era. This tracking detector includes the Inner Tracker, equipped with silicon pixel sensor modules, and the Outer Tracker, consisting of modules with two parallel stacked silicon sensors. The Outer Tracker front-end ASICs will be...
High-luminosity particle collider experiments such as the ones planned at the High-Luminosity Large Hadron Collider require ever-greater vertexing precision of the tracking detectors, necessitating reductions in the material budget of the detectors. Traditionally, the fractional radiation length ( x/X 0 ) of detectors is either estimated using know...
The Large Hadron Collider at CERN will undergo an upgrade in order to increase its luminosity to 7.5 × 10 ³⁴ cm ⁻² s ⁻¹ . The increased luminosity during this High-Luminosity running phase, starting around 2029, means a higher rate of proton-proton interactions, hence a larger ionizing dose and particle fluence for the detectors. The current tracki...
The Large Hadron Collider (LHC) at CERN will undergo major upgrades to increase the instantaneous luminosity up to 5–7.5×10 ³⁴ cm ⁻² s ⁻¹ . This High Luminosity upgrade of the LHC (HL-LHC) will deliver a total of 3000–4000 fb ⁻¹ of proton-proton collisions at a center-of-mass energy of 13–14 TeV. To cope with these challenging environmental conditi...
The Short Strip ASIC (SSA) is one of the four front-end chips designed for the upgrade of the CMS Outer Tracker for the High Luminosity LHC. Together with the Macro-Pixel ASIC (MPA) it will instrument modules containing a strip and a macro-pixel sensor stacked on top of each other. The SSA provides both full readout of the strip hit information whe...
VFAT3 is a 128-channel charge-sensitive front-end ASIC explicitly designed for the CMS GEM phase-2 upgrades. LHC is undergoing major upgrades for HL-LHC, where the particle rate is expected to increase up to 5 times with respect to the nominal LHC luminosity of 10 ³⁴ cm ⁻² s ⁻¹ . It is, therefore, necessary to monitor the evolution of the VFAT3 res...
To build silicon trackers of modern and future high-luminosity collider experiments, thousands of silicon strip modules have to be produced and tested. The modules in new trackers must reliably work usually during 5–10 years or more under harsh irradiation conditions, as it will be impossible to replace a failing module once installed inside the de...
The CMS Inner Tracker, made of silicon pixel modules, will be entirely replaced prior to the start of the High Luminosity LHC period. One of the crucial components of the new Inner Tracker system is the readout chip, being developed by the RD53 Collaboration, and in particular its analogue front-end, which receives the signal from the sensor and di...
During the operation of the CMS experiment at the High-Luminosity LHC the silicon sensors of the Phase-2 Outer Tracker will be exposed to radiation levels that could potentially deteriorate their performance. Previous studies had determined that planar float zone silicon with n-doped strips on a p-doped substrate was preferred over p-doped strips o...
Preconceptions are the subject of much research both in the field of pedagogy and in didactic spheres. They present a significant obstacle to the acquisition of new knowledge in many disciplines. Our work has enabled us to propose a formalism redefining each knowledge to be taught in a couple of elements: a model and a domain of validity1 (or DoV)....
Real-time particle track reconstruction in high energy physics experiments at colliders running at high luminosity is very challenging for trigger systems. To perform pattern-recognition and track fitting in online trigger system, the artificial Retina algorithm has been introduced in the field. Retina can be implemented in the state of the art FPG...
Les préconceptions ont été activement étudiées en tant qu’élément-clé des difficultés d’apprentissage. Elles ont été rapportées dans une large palette de disciplines, dont l’électricité. Nous investiguons ici l’application d’une formalisation particulière de ce phénomène à l’enseignement de la théorie des circuits en école d’ingénieurs. Notre démar...
The CMS detector at the CERN LHC features a silicon pixel detector as its innermost subdetector. The original CMS pixel detector has been replaced with an upgraded pixel system (CMS Phase-1 pixel detector) in the extended year-end technical stop of the LHC in 2016/2017. The upgraded CMS pixel detector is designed to cope with the higher instantaneo...
We propose a new instructional theory, the Domain of Validity (DoV) Framework, which offers a new way forward for designing teaching for conceptual change, while also resolving conflicts between existing theories related to common, difficult-to-change conceptions students have about particular scientific topics. We propose that knowledge consists o...
Real-time track tracking in high energy physics experiments at colliders running at high luminosity is very challenging for trigger systems. To perform pattern-recognition and track fitting in online trigger system, the artificial Retina algorithm has been introduced in the field. Retina can be implemented in the state of the art FPGA devices. Our...
Les erreurs récurrentes observées chez les étudiants peuvent parfois, voire souvent, être expliquées en exploitant l’idée de préconception selon laquelle un étudiant construit son apprentissage en s’appuyant sur des concepts antérieurs. Les préconceptions, parce qu’elles sont susceptibles d’entrer en conflit avec l’assimilation de nouveaux savoirs,...
During the high-luminosity phase of the LHC (HL-LHC), planned to start in 2027, the accelerator is expected to deliver an instantaneous peak luminosity of up to 7.5 x 10(34) cm(-2) s(-1). A total integrated luminosity of 3000 or even 4000 fb(-1) is foreseen to be delivered to the general purpose detectors ATLAS and CMS over a decade, thereby increa...
Positive position feedback is an attractive control law for the control of plants having no high frequency roll-off. The tuning of the parameters of the positive position feedback to obtain the desired closed-loop performance is quite challenging. This paper presents a technique to design the positive position feedback controller with the optimal d...
In 2017 a new pixel detector was installed in the CMS detector. This so-called Phase-1 pixel detector features four barrel layers in the central region and three disks per end in the forward regions. The upgraded pixel detector requires an upgraded data acquisition (DAQ) system to accept a new data format and larger event sizes. A new DAQ and contr...
Real-time track reconstruction in high-energy physics experiments at colliders running at high luminosity is very challenging for trigger systems. To perform pattern recognition and track fitting, artificial retina or Hough transformation algorithms have been introduced to the field typically implemented on state-of-the-art field programmable gate...
In response to the 2013 Update of the European Strategy for Particle Physics (EPPSU), the Future Circular Collider (FCC) study was launched as a world-wide international collaboration hosted by CERN. The FCC study covered an energy-frontier hadron collider (FCC-hh), a highest-luminosity high-energy lepton collider (FCC-ee), the corresponding 100 km...
In response to the 2013 Update of the European Strategy for Particle Physics (EPPSU), the Future Circular Collider (FCC) study was launched as a world-wide international collaboration hosted by CERN. The FCC study covered an energy-frontier hadron collider (FCC-hh), a highest-luminosity high-energy lepton collider (FCC-ee), the corresponding 100 km...
In response to the 2013 Update of the European Strategy for Particle Physics (EPPSU), the Future Circular Collider (FCC) study was launched as a world-wide international collaboration hosted by CERN. The FCC study covered an energy-frontier hadron collider (FCC-hh), a highest-luminosity high-energy lepton collider (FCC-ee), the corresponding 100 km...
Our research studies about student’s prior knowledge acting as learning difficulties (referred to as preconceptions) in electricity courses at university level led us to define knowledge as the association of two elements: a model and a domain of validity (DoV). This statement is the core of the DoV framework. This framework reveals its powerfulnes...
We review the physics opportunities of the Future Circular Collider, covering its e+e-, pp, ep and heavy ion programmes. We describe the measurement capabilities of each FCC component, addressing the study of electroweak, Higgs and strong interactions, the top quark and flavour, as well as phenomena beyond the Standard Model. We highlight the syner...
In response to the 2013 Update of the European Strategy for Particle Physics, the Future Circular Collider (FCC) study was launched, as an international collaboration hosted by CERN. This study covers a highest-luminosity high-energy lepton collider (FCC-ee) and an energy-frontier hadron collider (FCC-hh), which could, successively, be installed in...
In response to the 2013 Update of the European Strategy for Particle Physics, the Future Circular Collider (FCC) study was launched, as an international collaboration hosted by CERN. This study covers a highest-luminosity high-energy lepton collider (FCC-ee) and an energy-frontier hadron collider (FCC-hh), which could, successively, be installed in...
We review the physics opportunities of the Future Circular Collider, covering its e+e-, pp, ep and heavy ion programmes. We describe the measurement capabilities of each FCC component, addressing the study of electroweak, Higgs and strong interactions, the top quark and flavour, as well as phenomena beyond the Standard Model. We highlight the syner...
In response to the 2013 Update of the European Strategy for
Particle Physics (EPPSU), the Future Circular Collider (FCC) study
was launched as a world-wide international collaboration hosted by
CERN. The FCC study covered an energy-frontier hadron collider
(FCC-hh), a highest-luminosity high-energy lepton collider (FCC-ee),
the corresponding 100 km...
In response to the 2013 Update of the European Strategy for Particle Physics (EPPSU), the Future Circular Collider (FCC) study was launched as a world-wide international collaboration hosted by CERN. The FCC study covered an energy-frontier hadron collider (FCC-hh), a highest-luminosity high-energy lepton collider (FCC-ee), the corresponding 100 km...
In response to the 2013 Update of the European Strategy
for Particle Physics, the Future Circular Collider (FCC) study was
launched, as an international collaboration hosted by CERN. This
study covers a highest-luminosity high-energy lepton collider (FCCee) and an energy-frontier hadron collider (FCC-hh), which could,
successively, be installed in...
We review the physics opportunities of the Future Circular Collider, covering its e+e−, pp, ep and heavy ion
programmes.We describe the measurement capabilities of each FCC component, addressing the study of electroweak, Higgs
and strong interactions, the top quark and flavour, as well as phenomena beyond the Standard Model. We highlight the
synerg...
We introduce Gianduja, an automatic design method that generates communication-based behaviors for robot swarms. Gianduja extends Chocolate, a previously published design method. It does so by providing the robots with the capability to communicate using one message. The semantics of the message is not a priori fixed. It is the automatic design pro...
Un concept bien connu en didactique des sciences est celui de préconception. Fondé notamment par Piaget et Bachelard au début du XXe siècle, son essence est de considérer que l’élève n’arrive pas vierge dans une séquence d’apprentissage : ses connaissances préalables peuvent entrer en contradiction avec les connaissances à enseigner, jusqu’à consti...
This communication deals with misconceptions in the cognitive structure of 2nd-year engineering students at university level, especially in Circuit Theory. An examination analysis of almost 800 students’ examination scripts confirmed that these students are prone to misconceptions. Moreover, it revealed the latter are rarely, if ever, addressed by...
Real-time track reconstruction at high event rates is a major challenge for future experiments in high energy physics. To perform pattern-recognition and track fitting, artificial retina or Hough transformation methods have been introduced in the field which have to be implemented in FPGA firmware. In this note we report on a case study of a possib...
Il existe des similarités entre le processus d'apprentissage et le processus d'innovation scientifique (Espinoza, 2005). Tous deux consistent en la construction de nouvelles connaissances, en la création et l'acquisition de modèles toujours plus performants pour représenter la réalité. Selon Clement, « Si la recherche peut être vue comme une créati...
Cette communication traite des préconceptions présentes dans la structure cognitive d'étudiants universitaires dans le domaine des sciences, en particulier en théorie des circuits électriques. Une phase de diagnostic, via l'analyse de près de 800 copies d'examens, a révélé que nos étudiants sont sujets à des préconceptions rarement évoquées dans la...
For sub-28nm, process variations became more important. Clock distribution networks are sensitive to those variations because they lead to increased clock skew, which translates to a deterioration of the performance. In this scope, it is the first time that different existing processes are compared. We consider
self-aligned double patterning (SADP)...
In the past decades, the micro-electronic industry has been following the Moore's law to improve the performance of integrated circuits (ICs). However, it will probably be impossible to follow this law in the future due to physical limitations appearing with the miniaturization of the transistors below a certain threshold. In order to overcome this...
This paper presents a new sliding mode controller for the boost converter called Multi-Segments Sliding Mode Controller. This controller combines several switching functions. During transients, only one switching function is active, at any time, depending on the state of the converter. Hence, the transient is divided in several phases, with differe...
In the last decade, digital real-time emulators of power converters have replaced their analog counterparts, paving the way to the rapid prototyping of the controller. One of the main challenges with these emulators is the methodology employed to correctly simulate the abrupt changes in circuit behavior. In this paper we propose a diode control alg...
Cet article presente une partie des resultats d’une enquete menee en 2010 aupres des enseignants-chercheurs nommes a titre definitif de l’Universite libre de Bruxelles (ULB). Cette etude avait pour objectif de mieux connaitre la mission d’enseignement de cette population et de permettre, tant aux autorites de l’universite qu’aux acteurs concernes p...
A modular virtual data acquisition chain implemented on LabVIEW is presented in this article, which is intended to illustrate and teach instrumentation. The signal can be viewed at any point of the chain and under the influence of any parameter change. The acquisition chain accuracy and student applications are detailed in the case of an electroenc...
In this paper, we propose a new implementation method for the rapid prototyping of power converters. A Field-Programmable Gate Array emulates the temporal equations of the device while analog interfaces allow to use the platform to test control and protection systems in a nearly seamless way. A description of the converter based on an ideal on-off...
In past decades, the electronic industry has been following the Moore's law to improve the performance of CMOS integrated circuits (IC). However, it will probably be impossible to follow this law in the future due to physical limitations appearing with the miniaturization of the transistors below a certain threshold. In order to overcome this probl...
Recently, the academic and industrial communities have proposed new technologies in order to overcome the physical limitations of the silicon, and among them 3D-Stacked Integrated Circuits (3D-SIC). Manufacturing of 3D-SICs consists in piling up conventional CMOS ICs and creating vertical interconnections between them. This offers new perspectives...
As part of an instrumentation course, a problem-based learning framework was selected for laboratory instruction. Two acquisition chains were designed to help students carry out realistic instrumentation problems. The first tool is a virtual (simulated) modular acquisition chain that allows rapid overall understanding of the main problems in instru...
In this paper we present a design methodology and associated tool chain for efficient design of complex MPSoC architectures implemented using 3D-Stacked Integrated Circuits (3D-SIC). The proposed framework is based on a three step methodology that combines relatively accurate high-level, and two more accurate low-level prototyping tools. The high-l...
The paper presents Nessie, an original multicriteria exploration tool able to decide on functional and nonfunctional aspects of SoC's based on the application and platform descriptions and the costs (energy, execution time, area, ...). Indeed, the different performance prediction tools we can find in the literature, aiming at helping designers to t...
RESUME : Depuis 2002, la faculté des Sciences Appliquées de l'Université Libre de Bruxelles a introduit dans son cursus l'apprentissage par projet. Chaque année, les étudiants de BA1 (première année ingénieur civil) sont confrontés au défi de réaliser en groupe et sous la supervision d'un étudiant de MA1 (quatrième année) un dispositif technique co...
L'apprentissage par projet a été choisi pour les laboratoires du cours d'instrumentation. Deux chaînes d'acquisition ont été conçues de manière à fournir aux étudiants deux outils les aidant à réaliser leur projet. La première est une chaîne d'acquisition virtuelle permettant une compréhension rapide et globale des principaux problèmes de l'instrum...
To ensure low power consumption while maintaining flexibility and performance, future Systems-on-Chip (SoC) will combine several types of processor cores and data memory units of widely different sizes. To interconnect the IPs of these heterogeneous platforms, Networks-on-Chip (NoC) have been proposed as an efficient and scalable alternative to sha...
In this paper we present a flexible performance estimation tool called Nessie developed to provide system-on-chip designers with automated multi-objective design space exploration and its related tool called Yeti building and executing reusable closed-formed models. After reviewing the existing closed-formed expressions based and application/platfo...
This paper reports the development of a Wireless Body Area Network (WBAN) for sleep staging applications. A prototype biopotential sensor node has been designed for monitoring a multitude of biopotential signals. A system consisting of three of these nodes packaged in a headband enables wireless sleep stage monitoring. Preliminary results obtained...
We present a general learning model explaining in more depth how we learn (or fail to learn) models and theories. It specifically addresses the phenomenon of preconceptions introduced by the constructivist pedagogical approach. Nature of cognitive conflicts as well as existence, birth and resolution of preconceptions are clarified through a two-sta...
In this paper we present a general framework for the support of flexible models representation and execution in the context
of SoC design space exploration. Coming as a C++ library, it allows the user to gather models from its own and existing models
into larger and more complete models. Compared to existing modeling systems we introduce the notion...
Having analyzed recent papers, we present some new concepts helping to classify and understand the different kinds of models used in technology extrapolation, the specific discipline aimed at early technological bottlenecks detection and a priori performance estimation. We introduce several criteria allowing to organize explicitly the various relat...
Networks-on-chip have been proposed as the interconnect solution for building large systems-on-chip. Such platforms will be made of hardware cores, running concurrently to achieve high compute power and keep power consumption low. These platforms have many things in common with distributed systems. In this article we analyze the issues related to m...
To ensure low power consumption while maintaining flexibility and performance, future Systems-on-Chip (SoC) will combine several types of processor cores and data memory units of widely different sizes. To interconnect the IPs of these heterogeneous platforms, Networks-on-Chip (NoC) have been proposed as an efficient and scalable alternative to sha...
In design of high-frequency magnetic devices, various approaches have been used to provide calculation tools that are able to predict winding losses, including skin effect and proximity effect, in their two-dimensional (2-D) aspects. Up to now, these approaches have been mainly focused on giving quantitative results for specific cases. Because the...
Users expect future handheld devices to provide extended multimedia functionality and have long battery life. This type of application imposes heavy constraints on performance and power consumption and forces designers to optimize all parts of their platform. Evaluating the overall platform power breakdown is therefore critical to determine where t...
We provide a new closed-form formula that instantly calculates the 2D high-frequency ohmic losses (skin and proximity effects) in round wire windings. It has been obtained by overwriting the classical definition (shown to be erroneous) of the layer copper factor introduced in 1D analytical theories. Compared to similar previous formulas, the averag...
This paper deals with novel homogenization methods for the inclusion of skin and proximity effect in windings in finite-element (FE) models of electromagnetic devices. A general frequency-domain approach and its original extension to the time domain are proposed. In a preprocessing step the conductors (i.e. type of cross-section and packing, and fi...
In order to use Networks-on-Chip as communication infrastructure for heterogeneous, reconfigurable Systems-on-Chip, a set
of tools are needed that would allow for an evaluation of the performance of a particular network, and a fast implementation
of the system. In this paper we present two models that can be used in the design and implementation of...
Users expect future handheld devices to provide extended multimedia functionality and have long battery life. This type of application imposes heavy constraints on both (realtime) performance and energy consumption and forces designers to optimise all parts of their platform. In this experiment we focus on the different processor core design option...
In one-dimensional analytical theories aimed at calculating winding losses in magnetic devices, one usually introduces a "layer copper factor" to take layer porosity into account. The existence of this factor has been accepted since 1966 although it leads to nonphysical equations. This paper is a short theoretical discussion explaining: 1) how the...
Summary form only given. Optimum transformer design needs accurate windings losses calculation. The current harmonic spectrum and 2D field effects have both been reported to significantly influence the winding losses. Up to now, these two topics have always been treated separately. Thanks to a new analytical form which permits one to to include 2D...
This paper proposes an analysis of copper losses within a classical winding structure of power transformer (copper foil on secondary side). A model of such a structure with a semi-empirical formula, enhanced by 2D-finite element simulation, leads to further understanding of the copper losses mechanisms and associated design guidelines. Related prac...
A new formula aimed at calculating ohmic losses in switch-mode
power supply (SMPS) transformers is presented. It is based on intensive
two-dimensional (2-D) finite element method (FEM) simulations, the
results of which have been summarized in a closed-form formula following
a “semi-empirical” approach. The main benefit of this new
formula, specific...
In 1D analytical models aimed at calculating ohmic losses in magnetic devices subject to high-frequency effects, the “layer copper factor” is classically used to take layers composed of several conductors into account. The authors show that this well-known factor, introduced by Dowell in 1966, has no theoretical base due to an error in Dowell's ori...
Magnetic components play an important role in the technological
evolution towards increased power density of AC/DC power converters.
Planar transformers provide several advantages that have to be balanced
with the latest evolution of more classical transformer technology. This
paper analyses the interest of using planar transformer for AC/DC power...
A new closed-form formula aimed at calculating ohmic losses in switch-mode power supply transformers is presented. It is based on intensive 2D finite element method simulation. Only valid for one-layer-foil windings at the moment, it accurately covers cases where the classical Dowell's formula significantly underestimated the losses
The paper compares two methods for ohmic losses calculation in
switch-mode power supply transformers: Dowell's 1D approach and 2D
finite element method simulations (validated by measurements). Dowell's
method underestimates losses at the fundamental frequency for foil
windings, whereas harmonic losses are generally overestimated (depending
on condu...
We have developed a multi-objective performance exploration tool to help SoC designers to take decisions at the early stages of a flow. We demonstrate it on a real time video decoding application.
