60 research outputs found

    Algorithms for Cell Layout

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    Cell layout is a critical step in the design process of computer chips. A cell is a logic function or storage element implemented in CMOS technology by transistors connected with wires. As each cell is used many times on a chip, improvements of a single cell layout can have a large effect on the overall chip performance. In the past years increasing difficulty to manufacture small feature sizes has lead to growing complexity of design rules. Producing cell layouts which are compliant with design rules and at the same time optimized w.r.t. layout size has become a difficult task for human experts. In this thesis we present BonnCell, a cell layout generator which is able to fully automatically produce design rule compliant layouts. It is able to guarantee area minimality of its layouts for small and medium sized cells. For large cells it uses a heuristic which produces layouts with a significant area reduction compared to those created manually. The routing problem is based on the Vertex Disjoint Steiner Tree Packing Problem with a large number of additional design rules. In Chapter 4 we present the routing algorithm which is based on a mixed integer programming (MIP) formulation that guarantees compliance with all design rules. The algorithm can also handle instances in which only part of the transistors are placed to check whether this partial placement can be extended to a routable placement of all transistors. Chapter 5 contains the transistor placement algorithm. Based on a branch and bound approach, it places transistors in turn and achieves efficiency by pruning parts of the search tree which do not contain optimum solutions. One major contribution of this thesis is that BonnCell only outputs routable placements. Simply checking the routability for each full placement in the search tree is too slow in practice, therefore several speedup strategies are applied. Some cells are too large to be solved by a single call of the placement algorithm. In Chapter 7 we describe how these cells are split up into smaller subcells which are placed and routed individually and subsequently merged into a placement and routing of the original cell. Two approaches for dividing the original cell into subcells are presented, one based on estimating the subcell area and the other based on solving the Min Cut Linear Arrangement Problem. BonnCell has enabled our cooperation partner IBM to drastically improve their cell design and layout process. In particular, a team of human experts needed several weeks to find a layout for their largest cell, consisting of 128 transistors. BonnCell processed this cell without manual intervention in 3 days and its layout uses 15% less area than the layout found by the human experts

    Timing-Driven Macro Placement

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    Placement is an important step in the process of finding physical layouts for electronic computer chips. The basic task during placement is to arrange the building blocks of the chip, the circuits, disjointly within a given chip area. Furthermore, such positions should result in short circuit interconnections which can be routed easily and which ensure all signals arrive in time. This dissertation mostly focuses on macros, the largest circuits on a chip. In order to optimize timing characteristics during macro placement, we propose a new optimistic timing model based on geometric distance constraints. This model can be computed and evaluated efficiently in order to predict timing traits accurately in practice. Packing rectangles disjointly remains strongly NP-hard under slack maximization in our timing model. Despite of this we develop an exact, linear time algorithm for special cases. The proposed timing model is incorporated into BonnMacro, the macro placement component of the BonnTools physical design optimization suite developed at the Research Institute for Discrete Mathematics. Using efficient formulations as mixed-integer programs we can legalize macros locally while optimizing timing. This results in the first timing-aware macro placement tool. In addition, we provide multiple enhancements for the partitioning-based standard circuit placement algorithm BonnPlace. We find a model of partitioning as minimum-cost flow problem that is provably as small as possible using which we can avoid running time intensive instances. Moreover we propose the new global placement flow Self-Stabilizing BonnPlace. This approach combines BonnPlace with a force-directed placement framework. It provides the flexibility to optimize the two involved objectives, routability and timing, directly during placement. The performance of our placement tools is confirmed on a large variety of academic benchmarks as well as real-world designs provided by our industrial partner IBM. We reduce running time of partitioning significantly and demonstrate that Self-Stabilizing BonnPlace finds easily routable placements for challenging designs – even when simultaneously optimizing timing objectives. BonnMacro and Self-Stabilizing BonnPlace can be combined to the first timing-driven mixed-size placement flow. This combination often finds placements with competitive timing traits and even outperforms solutions that have been determined manually by experienced designers

    High performance algorithms for large scale placement problem

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    Placement is one of the most important problems in electronic design automation (EDA). An inferior placement solution will not only affect the chip’s performance but might also make it nonmanufacturable by producing excessive wirelength, which is beyond available routing resources. Although placement has been extensively investigated for several decades, it is still a very challenging problem mainly due to that design scale has been dramatically increased by order of magnitudes and the increasing trend seems unstoppable. In modern design, chips commonly integrate millions of gates that require over tens of metal routing layers. Besides, new manufacturing techniques bring out new requests leading to that multi-objectives should be optimized simultaneously during placement. Our research provides high performance algorithms for placement problem. We propose (i) a high performance global placement core engine POLAR; (ii) an efficient routability-driven placer POLAR 2.0, which is an extension of POLAR to deal with routing congestion; (iii) an ultrafast global placer POLAR 3.0, which explore parallelism on POLAR and can make full use of multi-core system; (iv) some efficient triple patterning lithography (TPL) aware detailed placement algorithms

    Conception et mise au point de l'électronique frontale du détecteur de pied de gerbe (Preshower) de l'expérience CMS

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    Modern particle physics collider experiments consist of a number of macroscopic modules each consisting of large number of sensors measuring charge deposition from traversing particles. The CMS Preshower detector is designed as a sampling calorimeter producing electromagnetic showers for incident electrons and photons resulting from LHC p-p interactions. The ultimate aim is to provide neutral pion / gamma separation reducing the background to the most promising Higgs channel, SM Higgs to 2 photons. The detector has 4300 silicon sensors each subdivided into 32 channels with a total sensitive area of 16.4 m2. Front-end microelectronics ASICs must measure the charge of each channel accurately with low noise and over a wide dynamic range (4 fC to 1600 fC) at the rate of 40 MHz within a harsh radiation environment. This thesis presents the design and development of the Preshower front-end electronics ASIC development, PACE. The first chapter introduces the Preshower experiment and defines the specification for PACE as derived from the physics. The second chapter examines the radiation environment, its effect on electronic devices, and design techniques / technologies that can resist to LHC radiation levels. Chapters 3 to 5 present the design and results of two PACE developments examining analog memories based on current and voltage sampling techniques. Experimental results from a Preshower electro-mechanical prototype tested in a particle beam are also given

    Support des applications multimédia dans les réseaux de prochaine génération

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    RÉSUMÉ Les applications multimĂ©dia sont devenues tellement populaires que certaines d’entre elles sont utilisĂ©es quotidiennement par les usagers. Cette popularitĂ© peut ĂȘtre attribuĂ©e Ă  plusieurs facteurs, tels que la diversiïŹcation du contenu et des services oïŹ€erts, l’accĂšs en tout temps grĂące Ă  la mobilitĂ© et Ă  la nomadicitĂ©, ainsi qu’aux avancĂ©es au niveau des architectures et des protocoles utilisĂ©s, aïŹn de supporter les requis plus exigeants de ces applications. Par exemple, ce qui Ă©tait jadis un simple appel tĂ©lĂ©phonique, se transforme dĂ©sormais en une vidĂ©oconfĂ©rence, permettant Ă  un nombre dynamique d’usagers d’y participer. Un autre exemple d’application multimĂ©dia, qui connait Ă©galement un essor fulgurant, est IP TeleVision (IPTV), soit la technologie permettant la transmission de la tĂ©lĂ©vision, en direct et sur demande, sur des rĂ©seaux IP. On retrouve Ă©galement sa version mobile, soit Mobile IP TeleVision (MobileTV). Du cĂŽtĂ© des opĂ©rateurs, le focus est mis sur le dĂ©ploiement des rĂ©seaux de prochaine gĂ©nĂ©ration. Les opĂ©rateurs sans-ïŹl se tournent vers les technologies cellulaires de quatriĂšme gĂ©nĂ©ration, telles que 3GPP Long Term Evolution (LTE), alors que ceux qui oïŹ€rent les services ïŹlaires regardent plutĂŽt vers les rĂ©seaux basĂ©s sur la ïŹbre optique, tels que Fiber to the Home (FTTH). Ces rĂ©seaux promettent d’augmenter le dĂ©bit oïŹ€ert, ainsi que de rĂ©duire la latence, soit deux critĂšres importants pour le dĂ©ploiement des applications multimĂ©dia Ă  grande Ă©chelle. MalgrĂ© ces avancĂ©es technologiques, il existe encore plusieurs obstacles au bon fonctionnement des applications multimĂ©dia. Dans cette optique, cette thĂšse se penche sur trois problĂ©matiques importantes dans les rĂ©seaux de prochaine gĂ©nĂ©ration, chacune faisant l’objet d’un article scientiïŹque. Les deux premiers volets s’attardent sur la convergence des rĂ©seaux ïŹxes et mobiles, ou Fixed-Mobile Convergence (FMC). Cette convergence vient brouiller la distinction entre les rĂ©seaux mobiles et les rĂ©seaux ïŹxes. Entre autre, elle permet Ă  un usager d’avoir accĂšs Ă  ses services, autant sur le rĂ©seau cellulaire (LTE, par exemple) que sur un rĂ©seau local (Wireless Fidelity (WiFi), par exemple). Pour s’y faire, l’usager est gĂ©nĂ©ralement muni d’un terminal pouvant se connecter sur les deux rĂ©seaux. La premiĂšre problĂ©matique soulevĂ©e dans cette thĂšse est au niveau de la prise de dĂ©cision de la relĂšve. En eïŹ€et, les deux protocoles de mobilitĂ© les plus populaires, soit Mobile IP (MIP) et Proxy Mobile IP (PMIP), adoptent deux approches diamĂ©tralement opposĂ©es. Avec le premier protocole, ce sont l’usager et son terminal qui prennent entiĂšrement en charge la relĂšve. MĂȘme si cette approche permet la FMC, les opĂ©rateurs prĂ©fĂšrent plutĂŽt garder le contrĂŽle sur la prise de dĂ©cision, aïŹn de pouvoir optimiser leur rĂ©seau. En eïŹ€et, avec MIP, beaucoup de messages de signalisation sont envoyĂ©s, ce qui gaspille des ressources rĂ©seaux, surtout au niveau de l’accĂšs radio, la partie la plus prĂ©cieuse du rĂ©seau. De plus, en ne sollicitant pas le rĂ©seau, le terminal ne prend pas nĂ©cessairement les meilleures dĂ©cisions. Il peut donc basculer vers un rĂ©seau qui est plus chargĂ© et qui ne garantit pas nĂ©cessairement ses exigences au niveau de la qualitĂ© de service. De ce fait, le protocole PMIP a Ă©tĂ© proposĂ©. Son approche est exactement Ă  l’opposĂ© de celle de MIP, soit la mobilitĂ© qui est entiĂšrement gĂ©rĂ©e par le rĂ©seau. De ce fait, la mobilitĂ© est masquĂ©e au niveau du terminal, qui pense toujours se trouver dans son rĂ©seau mĂšre. GrĂące Ă  l’ajout de nouveaux nƓuds dans le rĂ©seau, qui gĂšrent la mobilitĂ© Ă  la place du terminal, on Ă©limine la signalisation sur l’accĂšs radio. De plus, les informations supplĂ©mentaires que le rĂ©seau dĂ©tient lui permettront de prendre une meilleure dĂ©cision. Par contre, le problĂšme avec ce protocole est que, sans l’intervention du terminal, il lui est impossible de dĂ©tecter toutes les situations de relĂšves. Dans plusieurs cas, le rĂ©seau ïŹxe de l’opĂ©rateur est masquĂ© par un rĂ©seau interne, par exemple un rĂ©seau WiFi, et la dĂ©tection de ce rĂ©seau n’est possible que grĂące Ă  l’intervention du terminal. Ainsi, PMIP n’est pas un protocole qui se prĂȘte bien au dĂ©ploiement de FMC. Le premier article, qui s’intitule « Client-Based Network-Assisted Mobile IPv6 », s’attaque donc Ă  ce problĂšme, en proposant un nouveau protocole, basĂ© sur Mobile IP v6 (MIPv6), et qui introduit l’implication du rĂ©seau. Le rĂ©sultat obtenu est un protocole hybride qui combine les avantages de MIPv6 et de Proxy Mobile IP v6 (PMIPv6). Pour s’y faire, deux Ă©tapes ont Ă©tĂ© nĂ©cessaires. La premiĂšre consiste en une refonte du protocole MIPv6 qui, dans son Ă©tat actuel, Ă©tait diïŹƒcile Ă  modiïŹer, Ă  cause de ses spĂ©ciïŹcations qui sont lourdes. Le rĂ©sultat de cette Ă©tape est un protocole beaucoup plus lĂ©ger et oïŹ€rant uniquement les fonctionnalitĂ©s de base. Les autres fonctionnalitĂ©s, telles que les mĂ©canismes de sĂ©curitĂ©, ont Ă©tĂ© sĂ©parĂ©es dans des modules. En deuxiĂšme lieu, un nouveau module a Ă©tĂ© proposĂ©, qui introduit un nouveau nƓud dans le rĂ©seau, capable de gĂ©rer la mobilitĂ© du terminal. Ainsi, la collaboration entre le terminal et ce nƓud permet de rĂ©duire les messages de signalisation et d’optimiser les dĂ©cisions au niveau des relĂšves, tout en oïŹ€rant le support pour FMC. La deuxiĂšme problĂ©matique, sur laquelle la thĂšse porte, se trouve au niveau de la transparence de la relĂšve entre les deux rĂ©seaux. On parle d’une relĂšve qui est transparente si cette derniĂšre n’engendre aucune interruption des services de l’usager. Par exemple, un appel en cours, qui est dĂ©marrĂ© sur le rĂ©seau cellulaire, ne doit pas ĂȘtre interrompu lorsque la connexion bascule sur le rĂ©seau local, et vice-versa. Les applications visĂ©es, par notre travail, sont les applications multimĂ©dia en temps rĂ©Ă©l, notamment IPTV et MobileTV (en mode tĂ©lĂ©vision en direct). Ces applications emploient des protocoles de multidiïŹ€usion permettant l’envoi optimisĂ© de donnĂ©es Ă  partir d’une ou de plusieurs sources vers plusieurs destinataires, avec un nombre minimal de paquets. Le problĂšme avec ces applications est que, lorsqu’une relĂšve verticale survient (dans le cadre de FMC par exemple), la connexion est rompue et doit ĂȘtre rĂ©Ă©tablie. Ceci est dĂ» au fait que le terminal change son adresse IP, ce qui le force Ă  rejoindre ses services Ă  partir de la nouvelle adresse. Cette dĂ©connexion rĂ©sulte en une perte de paquets, se traduisant par une interruption de l’application de l’usager. Le second article, qui s’intitule « Seamless handover for multicast Mobile IPv6 traïŹƒc », propose une solution Ă  ce problĂšme. Cette solution consiste en l’ajout d’un nouveau nƓud, dans le rĂ©seau, dont le rĂŽle est de mettre en tampon les paquets perdus, lors de la relĂšve du terminal. Ainsi, lorsque ce dernier recouvre sa connectivitĂ©, il est en mesure de rĂ©cupĂ©rer ces paquets auprĂšs de ce nƓud. L’application de l’usager se dĂ©roule alors sans interruption. La troisiĂšme problĂ©matique abordĂ©e dans cette thĂšse porte sur la planiïŹcation des rĂ©seaux d’accĂšs, aïŹn de supporter les requis des applications multimĂ©dia au niveau du dĂ©bit. Pour que la FMC soit rĂ©ussie, il faut que le rĂ©seau local puisse supporter les dĂ©bits nĂ©cessaires de l’application. Le rĂ©seau WiFi interne n’étant gĂ©nĂ©ralement pas un problĂšme, la limitation se trouve plutĂŽt au niveau de l’accĂšs ïŹlaire. AïŹn d’augmenter les dĂ©bits oïŹ€erts, les opĂ©rateurs ont introduit la ïŹbre optique dans leurs rĂ©seaux, complĂ©mentant ainsi les mĂ©thodes traditionnelles, tels les paires de cuivre torsadĂ©es et le cĂąble coaxial. Ainsi, de nouvelles technologies optiques hybrides ont Ă©tĂ© proposĂ©es. Dans un contexte o`u une infrastructure est dĂ©jĂ  existante, le choix d’une technologie hybride est trĂšs attrayant, car l’opĂ©rateur peut rentabiliser son investissement prĂ©cĂ©dent, minimisant ainsi le coĂ»t de la mise Ă  jour. Par contre, dans un environnement vierge, il n’existe pas d’infrastructure Ă  rĂ©utiliser. Le consensus, dans un tel scĂ©nario, est que la meilleure technologie Ă  dĂ©ployer est celle qui n’emploie que des liens en ïŹbre optique, car elle oïŹ€re les meilleurs dĂ©bits ainsi que la plus grande ïŹ‚exibilitĂ© au niveau de l’évolutivitĂ©. La diïŹ€Ă©rence, au niveau du coĂ»t, devient moins grande et n’est plus nĂ©cessairement le critĂšre principal au niveau du choix de la technologie Ă  dĂ©ployer. Une des diïŹƒcultĂ©s, qui compliquent la planiïŹcation, est que ces rĂ©seaux sont souvent dĂ©ployĂ©s par les opĂ©rateurs, en phases. La planiïŹcation doit ĂȘtre alors dynamique et prendre en considĂ©ration la nature Ă©volutive de la demande des clients. Le troisiĂšme article, qui s’intitule « Dynamic GreenïŹeld Fiber to the Home Planning », propose donc une modĂ©lisation dynamique du problĂšme de planiïŹcation des rĂ©seaux d’accĂšs en ïŹbre optique. Le rĂ©sultat est un modĂšle mathĂ©matique linĂ©aire, en nombres entiers, qui prend en entrĂ©e des paramĂštres, tels que les demandes des clients, et qui produit la planiïŹcation minimisant le coĂ»t total du rĂ©seau et ce, sur plusieurs phases. Les rĂ©sultats numĂ©riques obtenus en simulant notre modĂšle montrent sa supĂ©rioritĂ© par rapport aux mĂ©thodes sĂ©quentielles existantes.--------- ABSTRACT Multimedia applications have been gaining momentum and are ïŹnding their way into everyday life. Their popularity can be attributed to several factors, such as the diversiïŹcation of content and services, ubiquitous access thanks to the mobility and nomadicity, as well as advances in architectures and protocols used to support their most demanding requirements. For example, what was once a simple phone call has morphed nowadays into a videoconference, allowing a dynamic number of users to participate. Another example of a multimedia application that gained popularity is IP TeleVision (IPTV), which is the technology that allows the transmission of live and on demand television, on IP networks. There also exists a mobile version, called Mobile IP TeleVision (MobileTV). From the operators’ point of view, the focus is put on the deployment of next generation networks. Wireless operators are therefore deploying fourth generation cellular technologies, such as 3GPP Long Term Evolution (LTE), while those oïŹ€ering wired connectivity are looking into ïŹber optical based networks, such as Fiber to the Home (FTTH). These new networks increase the rate oïŹ€ered, as well as reduce latency, which are two important criteria for the deployment of large-scale multimedia applications. However, despite these advances, there still exist several obstacles hindering the proper operation of multimedia applications. This thesis therefore focuses on three important issues in next generation networks, each of these subjects leading to a scientiïŹc article. The ïŹrst two works deal with the issues of the Fixed-Mobile Convergence (FMC). This convergence is blurring the distinction between mobile and ïŹxed networks. Among other things, it allows a user to have access to its services, both on the cellular network (LTE, for example) as well as on a local network (Wireless Fidelity (WiFi), for example). This is usually accomplished by equipping the user with a device with that can connect to both networks. The ïŹrst issue raised in this thesis is about the decision of when to execute a handover. The two most popular mobility protocols, Mobile IP (MIP) and Proxy Mobile IP (PMIP), approach this problem with diametrically opposed views. With the ïŹrst protocol, the decision is made by the user and his device. Although this approach allows for FMC, operators would much rather have complete control over the decision-making, in order to optimize their network. Indeed, with MIP, many signaling messages are sent, wasting valuable network resources, especially at the radio access, which is the most precious part of the network. Furthermore, by not involving the network, the decision taken by the device will not be necessarily optimal. It might request to switch to a more overloaded network, that cannot meet its demands of Quality of Service (QoS). For these reasons, the PMIP protocol was proposed. Its approach is the opposite of that of MIP, the mobility being managed entirely by the network. By doing so, the device is actually shielded from any aspect of the mobility, and is fooled into thinking that its always in its home network. This is possible by introducing new nodes in the networks that act on its behalf, which eliminates all signaling on the radio link. In addition, since the network is usually better suited to make the right decision, because of the additional information it holds, the mobility is optimized. However, the big issue that arises is that, without the intervention of the terminal, it is impossible to detect all the handover possibilities. In many cases, the operator’s ïŹxed network is hidden by an internal network, usually a WiFi network, and the detection of the network is only possible with the help of the terminal. Thus, PMIP is not a protocol that is well suited to deploy FMC. The ïŹrst article, entitled “Client-Based Network-Assisted Mobile IPv6”, therefore addresses this problem by proposing a new protocol based on Mobile IP v6 (MIPv6), in which we introduce the involvement of the network. The result is a hybrid protocol that draws upon the strength of MIPv6 and Proxy Mobile IP v6 (PMIPv6). To accomplish this, two steps were required. The ïŹrst consisted of a complete overhaul of the MIPv6 protocol, as in its current state, it was near impossible to make any modiïŹcations, because of the complexity and heaviness of its speciïŹcations. The result is a much more lightweight protocol which provides only basic functionality. Other features, such as security mechanisms, were separated into modules. In the second step, we proposed a new module, which introduces a new node in the network that can handle the terminal mobility. Thus, the collaboration of the terminal and the new node reduces the signaling messages and optimizes the decisions for handing over, while still oïŹ€ering support for FMC. The second issue that this thesis tackles is the seamlessness of a handover between two networks. A handover is deemed seamless if it does not cause any disruption to the user’s services. For example, a call that is in progress on the cellular network should not be interrupted when the connection switches to a local network, and the same goes for the other way around. The applications targeted by our work are multimedia applications operating in real-time , such as IPTV and MobileTV (in live television mode). These applications employ multicast protocols that are optimized for the transmission of data from one or more sources to multiple receivers, while using the minimum number of packets required. The problem, however, with these applications is that when a vertical handover occurs (in the case of FMC, for example), the connection is lost and must be re-established. This is because the terminal changes its IP address, which forces it to rejoin the services from the new address. This disconnection results in a packet loss, which entails an interruption of the user application. The second article, entitled “Seamless handover for multicast Mobile IPv6 traïŹƒc”, proposes a solution to this problem. This is accomplished by introducing a new node in the network, whose role is to buïŹ€er the lost packets while the handover is occurring. Thus, when the device reconnects, it is able to recover these packets. The user application is therefore able to proceed without interruption. The third issue addressed in this thesis focuses on the planning of access networks, to support the high bandwidth required by multimedia applications. For the FMC to be successful, it is necessary that the local network supports the bandwidth requirements. The internal WiFi network is generally not an issue, the limitation rather lies in the wired network. To increase the oïŹ€ered rates, operators have started introducing ïŹber optic links in their networks, complementing the traditional links, such as twisted pair copper and coaxial cable. Thus, new hybrid optical technologies have been proposed. In a context where an infrastructure already exists, the choice of a hybrid technology is very attractive, because the operator can leverage its previous investment and minimize the cost of the upgrade. However, in a new environment, there is no infrastructure to reuse. Therefore, the consensus in such a scenario is that the best technology to deploy is the one that only uses ïŹber optic links, as it oïŹ€ers the best rates and the greatest scalability. The cost diïŹ€erence is smaller and therefore no longer the main criterion for selecting the technology to deploy. One of the diïŹƒculties of network planning is that these networks are often deployed by operators in phases. Therefore, the planning must be dynamic and take into account the changing nature of customer demands. The third article, entitled “Dynamic GreenïŹeld Fiber to the Home Planning”, proposes a dynamic model for the network planning problem of ïŹber optic networks. The result is a linear integer mathematical model, which takes input parameters, such as customer demands, and produces a planning that minimizes the total cost of the network, over all of the phases. The numerical results obtained when simulating our solution show its superiority compared to existing sequential methods

    Development, Characterization, and Analysis of Silicon Microstrip Detector Modules for the CBM Silicon Tracking System

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    The future Facility for Antiproton and Ion Research (FAIR) at GSI, Germany, will enable scientists to create tiny droplets of cosmic matter in the laboratory—matter subject to extreme conditions usually found in the interior of stars or during stellar collisions. The Compressed Baryonic Matter (CBM) experiment at FAIR aims to explore the quantum chromodynamics (QCD) phase diagram at high densities and moderate temperatures. By colliding heavy ions at relativistic beam energies, the conditions inside these supermassive objects can be recreated for an exceptionally short amount of time. The CBM detector is a fixed-target multi-purpose detector designed for measuring hadrons, electrons and muons in elementary nucleon and heavy-ion collisions over the full FAIR beam energy range delivered by the SIS100 synchrotron. One of the core detectors of CBM is the Silicon Tracking System (STS), responsible for measuring the momentum and tracks of up to 700 charged particles produced in a central nucleus-nucleus collisions. Due to the required momentum resolution, the material budget of the STS must be minimized. Therefore, the readout electronics and the cooling and mechanical infrastructure are placed out of the detector acceptance. The double-sided silicon microstrip sensors are connected to the self-triggering frontend electronics using low-mass flexible microcables with a length of up to 50 cm. The main goal of this thesis was to develop a high-density interconnection technology based on copper microcables. We developed a low-mass double-layered copper microcable at the edge of modern fabrication technology. Based on the copper microcable, we developed a novel high-density interconnection technology, comprising fine-grain solder paste printing on the microcable and gold stud bumping on the die. The gold stud--solder technology combines a high automation capability with good mechanical and electrical properties, making it an interesting technology also for future detector systems. Building on the gold stud--solder technology, a fully customized bonder machine was developed and constructed in hardware and software. Its main purpose is the realization of the challenging interconnection between the microcable and the sensor. Key components of the machine are four step motors with a sub-micron step resolution, a dual-camera pattern recognition system, a heatable, temperature-controlled bond head and sensor plate, as well as tailor-made mechanical supports for the STS detector modules. With the help of this bonder machine, a full-scale STS detector module in the copper technology was built. The noise performance of the copper module was evaluated in a bias voltage scan. Very low noise levels were observed. Measurements of the absolute value of the signal with a radioactive source allowed us to estimate the signal-to-noise ratio of the module. The results of these measurements give us confidence that STS modules based on the copper technology can achieve a satisfying performance comparable to the modules built in the aluminium technology. Another essential component of the STS detector module is the frontend electronics chip. During this work, the version 2.1 of the STS-XYTER readout ASIC was extensively characterized. Noise discrepancies between odd and even channels and increasingly higher noise towards the higher channel numbers had been observed in the predecessor chip. Our measurements of the STS-XYTER2.1 verified that both issues were successfully resolved. Furthermore, the noise behavior of the ASIC with respect to input load capacitance was studied. This is essential to parametrize expected noise levels for the many kinds of detector modules employed in the STS, to which the measured noise levels can then be compared. Measurements of the noise levels as a function of shaping time showed that the overall noise level is practically independent of shaper peaking time. Radiation tests with 50 MeV protons were performed with copper microcables connected to the ASIC in a non-powered state. No indications of damage to the chip and interconnects could be observed. Finally, a complete STS detector module in aluminium technology was subjected to a pencil-like monochromatic beam of 2.7 GeV/c protons at the Cooling Synchrotron at the research center JĂŒlich. Several essential performance criteria of the detector module were evaluated. The best coincidence between the STS and the reference fiber hodoscopes was established based on time information. An excellent time resolution of a few nanoseconds could be demonstrated. Based on the best coincidence, the spatial resolution of the full system was determined to be a few hundred microns. This is in line with expectations, as the resolution is limited by the fiber hodoscope resolution. Charge distributions of 1-strip clusters showed a clear separation between the noise and the proton signal peak, with a signal-to-noise ratio above 20 for the p-- and n-side. The charge collection efficiency of the module was estimated to be 96%96 \%. The COSY beamtime enabled a first-time evaluation of the full analysis software chain with real data and the evaluation of the full electronic readout chain of STS. The experience gained at COSY is immensely helpful for commissioning and data analysis in more complex beam environments such as mCBM, where a subsample of the CBM detectors is exposed to the particles created in a heavy-ion collision in run-time scenarios closely resembling the final CBM environment

    Indigenous Life Projects and Extractivism

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    Exploring indigenous life projects in encounters with extractivism, the present open access volume discusses how current turbulences actualise questions of indigeneity, difference and ontological dynamics in the Andes and Amazonia. While studies of extractivism in South America often focus on wider national and international politics, this contribution instead provides ethnographic explorations of indigenous politics, perspectives and worlds, revealing loss and suffering as well as creative strategies to mediate the extralocal. Seeking to avoid conceptual imperialism or the imposition of exogenous categories, the chapters are grounded in the respective authors’ long-standing field research. The authors examine the reactions (from resistance to accommodation), consequences (from anticipation to rubble) and materials (from fossil fuel to water) diversely related to extractivism in rural and urban settings. How can Amerindian strategies to preserve localised communities in extractivist contexts contribute to ways of thinking otherwise

    RÎle du cortex pariétal postérieur dans le processus d'intégration visuomotrice - connexions anatomiques avec le cortex moteur et activité cellulaire lors de la locomotion chez le chat

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    La progression d’un individu au travers d’un environnement diversifiĂ© dĂ©pend des informations visuelles qui lui permettent d’évaluer la taille, la forme ou mĂȘme la distance et le temps de contact avec les obstacles dans son chemin. Il peut ainsi planifier en avance les modifications nĂ©cessaires de son patron locomoteur afin d’éviter ou enjamber ces entraves. Ce concept est aussi applicable lorsque le sujet doit atteindre une cible, comme un prĂ©dateur tentant d’attraper sa proie en pleine course. Les structures neurales impliquĂ©es dans la genĂšse des modifications volontaires de mouvements locomoteurs ont Ă©tĂ© largement Ă©tudiĂ©es, mais relativement peu d’information est prĂ©sentement disponible sur les processus intĂ©grant l’information visuelle afin de planifier ces mouvements. De nombreux travaux chez le primate suggĂšrent que le cortex pariĂ©tal postĂ©rieur (CPP) semble jouer un rĂŽle important dans la prĂ©paration et l’exĂ©cution de mouvements d’atteinte visuellement guidĂ©s. Dans cette thĂšse, nous avons investiguĂ© la proposition que le CPP participe similairement dans la planification et le contrĂŽle de la locomotion sous guidage visuel chez le chat. Dans notre premiĂšre Ă©tude, nous avons examinĂ© l’étendue des connexions cortico-corticales entre le CPP et les aires motrices plus frontales, particuliĂšrement le cortex moteur, Ă  l’aide d’injections de traceurs fluorescents rĂ©trogrades. Nous avons cartographiĂ© la surface du cortex moteur de chats anesthĂ©siĂ©s afin d’identifier les reprĂ©sentations somatotopiques distales et proximales du membre antĂ©rieur dans la partie rostrale du cortex moteur, la reprĂ©sentation du membre antĂ©rieur situĂ©e dans la partie caudale de l’aire motrice, et enfin la reprĂ©sentation du membre postĂ©rieur. L’injection de diffĂ©rents traceurs rĂ©trogrades dans deux rĂ©gions motrices sĂ©lectionnĂ©es par chat nous a permis de visualiser la densitĂ© des projections divergentes et convergentes pariĂ©tales, dirigĂ©es vers ces sites moteurs. Notre analyse a rĂ©vĂ©lĂ© une organisation topographique distincte de connexions du CPP avec toutes les rĂ©gions motrices identifiĂ©es. En particulier, nous avons notĂ© que la reprĂ©sentation caudale du membre antĂ©rieur reçoit majoritairement des projections du cĂŽtĂ© rostral du sillon pariĂ©tal, tandis que la partie caudale du CPP projette fortement vers la reprĂ©sentation rostrale du membre antĂ©rieur. Cette derniĂšre observation est particuliĂšrement intĂ©ressante, parce que le cĂŽtĂ© caudal du sillon pariĂ©tal reçoit de nombreux inputs visuels et sa cible principale, la rĂ©gion motrice rostrale, est bien connue pour ĂȘtre impliquĂ©e dans les fonctions motrices volontaires. Ainsi, cette Ă©tude anatomique suggĂšre que le CPP, au travers de connexions Ă©tendues avec les diffĂ©rentes rĂ©gions somatotopiques du cortex moteur, pourrait participer Ă  l’élaboration d’un substrat neural idĂ©al pour des processus tels que la coordination inter-membre, intra-membre et aussi la modulation de mouvements volontaires sous guidage visuel. Notre deuxiĂšme Ă©tude a testĂ© l’hypothĂšse que le CPP participe dans la modulation et la planification de la locomotion visuellement guidĂ©e chez le chat. En nous rĂ©fĂ©rant Ă  la cartographie corticale obtenue dans nos travaux anatomiques, nous avons enregistrĂ© l’activitĂ© de neurones pariĂ©taux, situĂ©s dans les portions des aires 5a et 5b qui ont de fortes connexions avec les rĂ©gions motrices impliquĂ©es dans les mouvements de la patte antĂ©rieure. Ces enregistrements ont Ă©tĂ© effectuĂ©s pendant une tĂąche de locomotion qui requiert l’enjambement d’obstacles de diffĂ©rentes tailles. En dissociant la vitesse des obstacles de celle du tapis sur lequel le chat marche, notre protocole expĂ©rimental nous a aussi permit de mettre plus d’emphase sur l’importance de l’information visuelle et de la sĂ©parer de l’influx proprioceptif gĂ©nĂ©rĂ© pendant la locomotion. Nos enregistrements ont rĂ©vĂ©lĂ© deux groupes de cellules pariĂ©tales activĂ©es en relation avec l’enjambement de l’obstacle: une population, principalement situĂ©e dans l’aire 5a, qui dĂ©charge seulement pendant le passage du membre au dessus del’entrave (cellules spĂ©cifiques au mouvement) et une autre, surtout localisĂ©e dans l’aire 5b, qui est activĂ©e au moins un cycle de marche avant l’enjambement (cellules anticipatrices). De plus, nous avons observĂ© que l’activitĂ© de ces groupes neuronaux, particuliĂšrement les cellules anticipatrices, Ă©tait amplifiĂ©e lorsque la vitesse des obstacles Ă©tait dissociĂ©e de celle du tapis roulant, dĂ©montrant l’importance grandissante de la vision lorsque la tĂąche devient plus difficile. Enfin, un grand nombre des cellules activĂ©es spĂ©cifiquement pendant l’enjambement dĂ©montraient une corrĂ©lation soutenue de leur activitĂ© avec le membre controlatĂ©ral, mĂȘme s’il ne menait pas dans le mouvement (cellules unilatĂ©rales). Inversement, nous avons notĂ© que la majoritĂ© des cellules anticipatrices avaient plutĂŽt tendance Ă  maintenir leur dĂ©charge en phase avec l’activitĂ© musculaire du premier membre Ă  enjamber l’obstacle, indĂ©pendamment de sa position par rapport au site d’enregistrement (cellules bilatĂ©rales). Nous suggĂ©rons que cette disparitĂ© additionnelle dĂ©montre une fonction diversifiĂ©e de l’activitĂ© du CPP. Par exemple, les cellules unilatĂ©rales pourraient moduler le mouvement du membre controlatĂ©ral au-dessus de l’obstacle, qu’il mĂšne ou suive dans l’ordre d’enjambement, tandis que les neurones bilatĂ©raux sembleraient plutĂŽt spĂ©cifier le type de mouvement volontaire requis pour Ă©viter l’entrave. Ensembles, nos observations indiquent que le CPP a le potentiel de moduler l’activitĂ© des centres moteurs au travers de rĂ©seaux corticaux Ă©tendus et contribue Ă  diffĂ©rents aspects de la locomotion sous guidage visuel, notamment l’initiation et l’ajustement de mouvements volontaires des membres antĂ©rieurs, mais aussi la planification de ces actions afin d’adapter la progression de l’individu au travers d’un environnement complexe.When progressing through a varied environment, an individual will depend on visual information to evaluate the size, shape or the distance and time to contact of objects in his path. This will allow him to plan in advance the gait requirements necessary to avoid or step over these obstacles. This concept is also applicable in situations where the subject must reach a target, as with a predator chasing down its prey. The neural structures involved in generating voluntary gait modifications during locomotion have been extensively studied, but relatively little information is available on the processes that integrate visual information to plan these movements. Numerous studies in the primate suggest that the posterior parietal cortex (PPC) plays an important role in the preparation and execution of visually-guided reaching movements. In this thesis, we investigated the proposition that the PPC is similarly involved in the planning and control of visually-guided locomotion in the cat. Our first study examined the extent of cortico-cortical connections between the PPC and the more frontal motor areas, particularly the motor cortex, using injections of fluorescent retrograde tracers. We mapped the cortical surface of anaesthetized cats to identify the somatotopical representations of the distal and proximal forelimb in the rostral portion of the motor cortex, the forelimb representation in the caudal motor area, and also the hindlimb representation. The injection of different tracers in two selected regions, for every cat, allowed us to visualize the density of divergent and convergent parietal projections to these motor sites. Our analysis revealed a distinct topographical organization of parietal connections with all of the identified motor regions. In particular, the caudal motor representation of the forelimb primarily received projections from the rostral bank of the parietal cortex, while the caudal portion of the PPC strongly projected to the rostral forelimb representation. The latter observation is particularly interesting, since the caudal bank of the PPC receives numerous visual inputs and its target, the rostral motor region, is well-known for its involvement in voluntary motor functions. Therefore, this study suggests that the PPC, through extensive connections with the different somatotopic representations of the motor cortex, could constitute an ideal neural substrate for processes such as inter- and intra-limb coordination, as well as the modulation of visually-guided voluntary movements. Our second study tested the hypothesis that the PPC participates in the modulation and planning of voluntary gait modifications during locomotion in the cat. Using the cortical mapping established in our anatomical study, we recorded the activity of parietal neurons, localized in parts of areas 5a and 5b which are known to project strongly towards motor regions involved in forelimb movements. These recordings were obtained during a locomotion task requiring the cat to step over several obstacles of different sizes. By dissociating the speed of the obstacles from that of the treadmill onto which the cat is walking, our experimental protocol also allows us to increase the importance of visual information from the obstacles and to separate it from the influx of proprioceptive influx generated during locomotion. Our recordings revealed two groups of parietal cells on the basis of their activity in relation with the step over the obstacle: one population, mostly localized in area 5a, discharged solely as the lead forelimb passed over the obstacle (step-related cells), and another group, mainly found in area 5b, that showed significant activity at least one step cycle before the gait modification (step-advanced cells). Additionally, we observed an increase of cell activity in these groups, but particularly in step-advanced cells, when the speed of the obstacles was dissociated from that of the treadmill, demonstrating the growing importance of visual information as the task’s difficulty is increased. Finally, a great number of step-related cells were found to discharge specifically in correlation with muscle activity in the contralateral forelimb, regardless of whether or not it led over the obstacle (limb-specific cells). Inversely, the majority of step-advanced neurons tended to maintain their discharge in phase with the leading limb during the gait modification, independently of its position in relation with the recording site (limb-independent cells). We suggest that this additional disparity indicates diversified functions in PPC activity. For example, limb-specific cells could be involved in modulating the movement of the contralateral forelimb over the obstacle, regardless of its order of passage, while limb-independent neurons could instead specify the type of voluntary movement required to overcome the obstacle. Together, our observations indicate that the PPC can potentially influence the activity of motor centers through extensive cortical networks, and contributes to different aspects of visually-guided locomotion, such as initiation and modulation of voluntary forelimb movements, as well as the planning of these gait modifications to allow an individual to walk through a complex environment
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