• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 36
  • 24
  • 20
  • 8
  • 6
  • 3
  • 3
  • 3
  • 2
  • 2
  • 2
  • 1
  • Tagged with
  • 118
  • 29
  • 21
  • 16
  • 15
  • 14
  • 13
  • 13
  • 12
  • 11
  • 11
  • 10
  • 10
  • 10
  • 10
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
111

Communication synaptique et non-synaptique entre neurones et cellules précurseurs d’oligodendrocytes dans le cortex somatosensoriel / Synaptic and non-synaptic communication between neurons and oligodendrocyte precursor cells in the somatosensory cortex

Maldonado Rojas, Paloma P. 09 December 2013 (has links)
Les cellules précurseur d'oligodendrocytes (CPOs) représentent la majeure source d'oligodendrocytesmyélinisants durant le développement post-natal. Ces progéniteurs, identifiés par l'expression du protéoglycane NG2, sont non seulement extrêmement abondants avant la myélinisation, mais ils persistent aussi dans le cerveau mature. À l'instar d'autres cellules non-neuronales, elles expriment un large panel de canaux ioniques et de récepteurs pour des neurotransmetteurs. Cependant, ils sont uniques de part leur capacité à recevoir de véritables contacts synaptiques neuronaux glutamatergiqueset GABAergiques. Durant cette thèse, nous avons caractérisé les propriétés électrophysiologiques des CPOs durant le développement post-natal du cortex en champ de tonneaux de la souris (premier mois post-natal). En effectuant des enregistrements de patch-clamp, des analyses par RT-PCR sur cellule unique et des analyses pharmacologiques, nous avons observé que la courbe I-V à rectification sortante devient linéaire durant le développement, résultant d'une régulation positive de l'expression des canaux potassiques de type Kir4.1. Dotés de ces canaux, les CPOs adultes sont capables de détecter les augmentations locales de potassium extracellulaire générées par l'activité neuronale. Cette régulation positive développementale des canaux Kir4.1 dans les CPOs révèle que ces cellules ont un gain de fonction durant le développement, leur conférant la capacité de communiquer avec les neurones via un mécanisme non-synaptique lié au potassium. Ce changement développemental soutient aussi l'idée que les CPOs sont probablement plus que des progéniteurs. Dans la deuxième partie de cette thèse, nous nous sommes intéressés à l'étude des patrons de connectivité du réseau GABAergique interneurones-CPOs dans le cortex en champ de tonneaux jeune (deuxième semaine post-natale). Dans un premier temps, nous avons tiré avantage de la haute précision latérale et axiale de la photolyse holographique en mono-photon pour stimuler les interneurones GABAergiques avec une résolution à l'échelle de la cellule, de manière à évoquer un potentiel d'action. Nous avons ensuite utilisé cette technique pour cartographier la connectivité entre interneurones et CPOs. Nous avons trouvé que la probabilité de connexion des CPOs est près de moitié moins que celle des cellules pyramidales, et implique plutôt une microcircuitrie locale. De plus, en effectuant des enregistrements pairés, nous avons observé que les CPOs sont contactés transitoirement par des interneurones à décharge rapide et à décharge régulière. Ces connections se caractérisents pour la présence d'un ou deux sites de libération uniquement. Étonnamment, les sites post-synaptiques contenant des récepteurs GABAA avec la sous-unité γ2 sont principalement connectés par les interneurones à décharge rapide, indiquant que ces cellules constituent une afférence spécifique auprès des CPOs. Ici nous décrivons pour la première fois l'émergence de réseaux corticaux spécifiques entre neurones et cellules non-neuronales. / Oligodendrocyte precursor cells (OPCs) are the main source of myelinating oligodendrocytes during postnatal development. These progenitors, identified by the expression of the proteoglycan NG2, are extremely abundant before myelination, but also persist in the mature brain. Similarly to other non-neuronal cells they express a wide range of ionic and ligand-gated ion channels. However, they are unique by their ability to receive truly glutamatergic and GABAergic synaptic contacts from neurons. During this thesis, we characterized the electrophysiological properties of OPCs during the postnatal development of the mouse somatosensory cortex (post postnatal month). By performing patch-clamp recordings, single-cell RT-PCR analyses and pharmacological approaches, we found that outwardly rectifying I-V curves become linear during development, as the result of an upregulation of Kir4.1 potassium channels. Endowed with these channels, adult OPCs are able to sense local extracellular potassium increases generated by neuronal activity. This developmental upregulation of Kir4.1 channels in OPCs revealed that these cells gain physiological properties during development, conferring them the capacity to communicate with neurons, via a non-synaptic potassium-mediated mechanism. This developmental change also supports the view that OPCs are probably more than simple progenitors. In the second part of this thesis, we were interested in study the connectivity patterns underlying the GABAergic interneuron-OPC network in the young somatosensory cortex (second postnatal week). First, we took advantage of the high lateral and axial precision of one-photon holographic photolysis to stimulate GABAergic interneurons at a single cell resolution in order to evoke an action potential. We then used this technique to map the connectivity between interneurons and OPCs. We found that the connectivity probability of OPCs was around half less than that of pyramidal cells and involved more local microcircuits. In addition, by performing paired-recordings, OPCs showed to be transiently contacted by fast-spiking (FSI) and non-fast-spiking (NFSI) interneurons, through single or double release sites. Interestingly, postsynaptic sites containing GABAA receptors with the γ2 subunit were predominantly connected by FSI, indicating that these cells provide a specific input to OPCs. Here we described for the first time the emergence of specific cortical network between neurons and non-neuronal cells. In conclusion, this thesis contributed to get a better understanding of the different modes of communication between neurons and OPCs and the establishment of new signaling mechanisms used by neurons to control the activity of these precursors.
112

Komplexní systém řízení výroby stroje plnící linky lahví / The complex control system of production of bottle filling line machine

Karola, Ladislav January 2012 (has links)
The Master’s Thesis is focused to introduction MES systems and factory information systems. Describes main advantages of applying MES systems and describes concept of Six Big Losses, which characterise main losses in production. For quantification of losses are used indicators like OEE. Next part is simulation data of Filler Machine and producing via OPC Server. Main application made in software SIMATIC IT by Siemens is collecting, processing and archiving data to PPA database due to rules and setups. Presentation of data is powered by Data Report which provides overview of efficiency and main losses in production.
113

Univerzální měřící ústředna / Universal Measurement Station

Šantavý, Marek January 2012 (has links)
The aim of this thesis is to create data acquisition application. The software module is designed for the industrial panel PC. Power Panel 520 from Bernecker + Reiner and the data acquisition board NI USB-6215 from National Instruments represent the fundamental hardware components for this project. Data acquisition and visualization tasks are controlled by a standalone application made in LabVIEW 2011. OPC, industrial standard in communication, is responsible for mutual interconnection between control (PLC) and data acquisition part. Network shared variables and Apple iPad 2 allow remote surveillance for operator. Finally, the creation of user-friendly interface and integration of technologies from different vendors, are main goals of this project.
114

Model třídicí linky v systému Tecnomatix Process Simulate / Sorting line model implemented by Tecnomatix Process Simulate

Prokop, Michal January 2017 (has links)
This master‘s thesis is about how to create a virtual model of a sorting line by using Tecnomatix Process Simulate program. In this master‘s thesis is describe non-robotics operation as a controlling conveyor, material flow, working with sensors and simulaton of manufactory process. In the second part of my master’s thesis I realise virtual commissioning for this model of sorting line. I made program for real PLC and conected with model of sorting line via OPC server. I made SCADA aplication for users too. This model will be used in lessons and students will program PLC for controlling. In master’s thesis I explain, how to work in simulation environment Tecnomatix Process Simulate too.
115

Development of Advanced Process Control for Controlling a Digital Twin as a Part of Virtual Commissioning

Uddin, Md Mehrab January 2021 (has links)
Over the last few decades, the complexity and variety of automation systems have increased dramatically. Commissioning has grown more and more critical for the entire industry. Conventional commissioning is time-consuming and expensive. It's always been a challenge in manufacturing to put new designs into production or implement new technologies, control codes, or tactics. In Virtual Commissioning (VC), control programs of the physical system's Digital Twin (DT) can be validated in Software-in-the-Loop (SIL) before the actual commissioning. The emergence of new VC tools and methods has become a tremendous advantage, bringing the values of shorter duration, flexibility, and lower risks to the commissioning process. In this thesis, advanced process control was developed using the software Matlab and Simulink in conjunction with the engineering tools S7-PLCSIM Advanced and STEP 7 TIA Portal to conduct VC. A VC approach with four key steps is taken to evaluate the possibility of validating advanced process control. The steps are modeling DT of a rolling mill, model-based control design, simulation model development in Simulink, communication between the simulation model and the PLC program using S-7 TIA Portal, and PLCSIM Advanced. Also, a simulated Human-Machine Interface was designed to operate and visualize the process. VC of the rolling mill process was verified and validated by Model-in-the-Loop (MIL) and SIL simulation. The simulation gives satisfactory results as both MIL and SIL show identical outputs of the process.
116

Robustness versus performance tradeoffs in PID tuning

Amiri, Mohammad Sadegh 11 1900 (has links)
Proportional, integral and derivative (PID) controller tuning guidelines in process industry have been in place for over six decades. Nevertheless despite their long design history PID tuning has remained an ‘art’ and no single comprehensive solution yet exists. In this study various considerations, with new and different perspectives, have been taken into account in PID tuning design. This study explores the issue of PID tuning from a practical point of view with particular focus on robust design in the presence of typical problems in process industry: process changes, valve stiction effects and unmeasured disturbances. The IMC tuning rule is recommended for setpoint tracking, while in the case of regulation, a newly proposed tuning rule, based on a combination of IMC and Ziegler-Nichols method, is demonstrated to give satisfactory results. The results were evaluated by simulation and were also validated on a computer-interfaced pilot scale continuous stirred tank heater (CSTH) process. / Chemical Engineering
117

Robustness versus performance tradeoffs in PID tuning

Amiri, Mohammad Sadegh Unknown Date
No description available.
118

Rhetoric or reality : US counterinsurgency policy reconsidered

Todd, Maurice L. January 2015 (has links)
This study explores the foundations of US counterinsurgency policy and doctrine in order to better understand the main historical influences on that policy and doctrine and how those influences have informed the current US approach to counterinsurgency. The results of this study indicate the US experience in counterinsurgency during the Greek Civil War and the Huk Rebellion in the Philippines had a significant influence on the development of US counterinsurgency policy and doctrine following World War II through the Kennedy presidency. In addition, despite a major diversion from the lessons of Greece and the Philippines during the Vietnam War, the lessons were re-institutionalized in US counterinsurgency policy and doctrine following the war and continue to have significant influence today, though in a highly sanitized and, therefore, misleading form. As a result, a major disconnect has developed between the “rhetoric and reality” of US counterinsurgency policy. This disconnect has resulted from the fact that many references that provide a more complete and accurate picture of the actual policies and actions taken to successfully defeat the insurgencies have remained out of the reach of non-government researchers and the general public. Accordingly, many subsequent studies of counterinsurgency overlook, or only provide a cursory treatment of, aspects that may have had a critical impact on the success of past US counterinsurgency operations. One such aspect is the role of US direct intervention in the internal affairs of a supported country. Another is the role of covert action operations in support of counterinsurgency operations. As a result, the counterinsurgency policies and doctrines that have been developed over the years are largely based on false assumptions, a flawed understanding of the facts, and a misunderstanding of the contexts concerning the cases because of misleading, or at least seriously incomplete, portrayals of the counterinsurgency operations.

Page generated in 0.0431 seconds