Littérature scientifique sur le sujet « Firing unit »

Thesis (Masters Diploma (Electrical Engineering)--Cape Technikon, Cape Town, 1988<br>The subject of this thesis is the development of ahighly ruggedised, reliable electronic circuit. The circuit is to be used for the initiation of fuze heads and to charge a capacitor for later use in apyrotechnic chain. This circuit and its associated packaging will be called the firing unit. The thesis can be broadly divided into the following facets. I. The definition study, which defines what is needed and proposed means of achieving the customer requirements. 11. The design of the electronic circuitry in the system. Ii!. The design of the packaging containing the electronics. Iv. Adaptation of environmental testing, to verify system design. V. Implementation of environmental testing. Vi. Reliability analysis. Vii. Failure analysis and the determination of the effect of the supposed failure. Actions vto vii were used as inputs to improve 11 and ill, so achieving optimum performance and safety. The whole system was designed with the overriding objective of reliability and safety of personnel and equipment.

Muscle force is regulated by varying two main motor unit properties: the recruitment and the firing rates of motor units. Discrepancies still exist on the mechanisms involved in motor unit control and muscle force generation. This study investigated the behavior of motor unit firing rate during sustained fatiguing contractions and the motor unit parameters that are most likely to influence force fluctuation increase. We also studied the firing rate of motor units during linearly increasing force contractions up to maximum, or near maximum voluntary contraction force, at different rates of force increase, and developed an equation that models the firing rate behavior as a function of increasing excitation to the motor unit pool. Results were used to create a model of muscle force production that is based on verifiable physiological concepts and data. The model also includes the concept of common drive, i.e. of an oscillatory common input received by all motor units in the motor unit pool, the time-dependent changes of motor unit twitches, and a feedback loop to simulate force generation in a target-force tracking mode. Simulations showed that the model is able to mimic the force and firing rate patterns which have been experimentally observed during repeated contractions sustained to exhaustion: the excitation to the motoneuron pool must be adjusted in response to an increased or decreased force generation capacity of the muscle fibers, and the firing rates of all motor units respond consequently with a decreased or increased firing rate. The simulation of prolonged contractions showed that the increase in force variability may be attributed to the gradual recruitment of higherrecruitment threshold larger-amplitude force twitch motor units. The level of cross-correlation between firing rates appeared to influence force variability, whereas the variability in the firing rates had no clear effect on force variability.<br>Il controllo della forza muscolare si basa principalmente su due fenomeni: il reclutamento di unità motorie e la regolazione della loro frequenza di scarica. Molti aspetti riguardanti i meccanismi coinvolti nel controllo delle unità motorie e nella generazione di forza muscolare restano ancora da investigare. Parte del lavoro di questa tesi ha riguardato lo studio del comportamento della frequenza di scarica delle unità motorie e dei parametri alla base dell’incremento delle fluttuazioni dell’output di forza durante l’esecuzione di contrazioni muscolari sostenute fino all’affaticamento. Inoltre, è stato analizzato il comportamento della frequenza di scarica delle unità motorie durante lo svolgimento di contrazioni muscolari a livelli di forza crescente fino alla massima forza di contrazione volontaria (a diverse velocità di incremento della forza); ed è stata messa a punto una equazione in grado di modellare il comportamento della frequenza di scarica in funzione dell’eccitazione ricevuta dal pool di unità motorie. I risultati di questa prima analisi sono serviti per creare un modello di produzione della forza muscolare basato su dati fisiologici verificabili. Il modello include il concetto di “common drive”, ovvero di un input oscillatorio comune ricevuto da tutte le unità motorie del pool; la dipendenza temporale dei “twitch” di forza delle unità motorie; ed un “feedback loop” per simulare la generazione di forza in contrazioni in “target-force tracking mode”. Si è dimostrato come il modello sviluppato sia in grado di simulare il pattern di forza e il comportamento delle unità motorie sperimentalmente osservati durante l’esecuzione di contrazioni prolungate e sostenute fino all’affaticamento. In particolare, si è potuto osservare come l’eccitazione ricevuta dal pool di unità motorie si modifichi in seguito ad un aumento o ad una diminuzione della capacità di produrre forza delle fibre muscolari e come la variazione dell’eccitazione comporti di conseguenza una diminuzione o un aumento della frequenza di scarica delle unità motorie e del numero di unità motorie attive. La simulazione di contrazioni muscolari prolungate ha anche evidenziato come la crescente variabilità della forza muscolare sia da attribuire al reclutamento di unità motorie caratterizzate da “twitch” di ampiezza maggiore e da un maggiore grado di cross-correlazione tra la frequenza di scarica delle unità motorie attive, mentre la variabilità della frequenza di scarica non sembra influire sull’output di forza.

EMG signal decomposition is the process of resolving a composite EMG signal into its constituent motor unit potential trains (classes) and it can be configured as a classification problem. An EMG signal detected by the tip of an inserted needle electrode is the superposition of the individual electrical contributions of the different motor units that are active, during a muscle contraction, and background interference. <BR>This thesis addresses the process of EMG signal decomposition by developing an interactive classification system, which uses multiple classifier fusion techniques in order to achieve improved classification performance. The developed system combines heterogeneous sets of base classifier ensembles of different kinds and employs either a one level classifier fusion scheme or a hybrid classifier fusion approach. <BR>The hybrid classifier fusion approach is applied as a two-stage combination process that uses a new aggregator module which consists of two combiners: the first at the abstract level of classifier fusion and the other at the measurement level of classifier fusion such that it uses both combiners in a complementary manner. Both combiners may be either data independent or the first combiner data independent and the second data dependent. For the purpose of experimentation, we used as first combiner the majority voting scheme, while we used as the second combiner one of the fixed combination rules behaving as a data independent combiner or the fuzzy integral with the lambda-fuzzy measure as an implicit data dependent combiner. <BR>Once the set of motor unit potential trains are generated by the classifier fusion system, the firing pattern consistency statistics for each train are calculated to detect classification errors in an adaptive fashion. This firing pattern analysis allows the algorithm to modify the threshold of assertion required for assignment of a motor unit potential classification individually for each train based on an expectation of erroneous assignments. <BR>The classifier ensembles consist of a set of different versions of the Certainty classifier, a set of classifiers based on the nearest neighbour decision rule: the fuzzy <em>k</em>-NN and the adaptive fuzzy <em>k</em>-NN classifiers, and a set of classifiers that use a correlation measure as an estimation of the degree of similarity between a pattern and a class template: the matched template filter classifiers and its adaptive counterpart. The base classifiers, besides being of different kinds, utilize different types of features and their performances were investigated using both real and simulated EMG signals of different complexities. The feature sets extracted include time-domain data, first- and second-order discrete derivative data, and wavelet-domain data. <BR>Following the so-called <em>overproduce and choose</em> strategy to classifier ensemble combination, the developed system allows the construction of a large set of candidate base classifiers and then chooses, from the base classifiers pool, subsets of specified number of classifiers to form candidate classifier ensembles. The system then selects the classifier ensemble having the maximum degree of agreement by exploiting a diversity measure for designing classifier teams. The kappa statistic is used as the diversity measure to estimate the level of agreement between the base classifier outputs, i. e. , to measure the degree of decision similarity between the base classifiers. This mechanism of choosing the team's classifiers based on assessing the classifier agreement throughout all the trains and the unassigned category is applied during the one level classifier fusion scheme and the first combiner in the hybrid classifier fusion approach. For the second combiner in the hybrid classifier fusion approach, we choose team classifiers also based on kappa statistics but by assessing the classifiers agreement only across the unassigned category and choose those base classifiers having the minimum agreement. <BR>Performance of the developed classifier fusion system, in both of its variants, i. e. , the one level scheme and the hybrid approach was evaluated using synthetic simulated signals of known properties and real signals and then compared it with the performance of the constituent base classifiers. Across the EMG signal data sets used, the hybrid approach had better average classification performance overall, specially in terms of reducing the number of classification errors.

In questa tesi, sono state realizzate tre diverse board: un DC-DC per il supply, un control unit per programmare i segnali d'ingresso del driver, un firing unit che contiene il chip principale(driver e GaN). Abbiamo usato il nitruro di galio perché è meglio adatto del silicio ad alte frequenze. L'obbiettivo principale è di raggiungere 50A di picco di corrente con soli 5ns di pulse. Sono stati usati Altium design per il disegno delle board e Ansys per l'evaluazione delle induttanze parassite. Questo ultimo crea diversi problemi e può limitare il raggiungimento del picco di corrente. Quindi bisogna fare il layout tenendo molta attenzione ai parassiti<br>In our three years of work, we have achieved the realization of a Firing unit board with the GaN and driver in a system in package. Three different boards were realized: A first board with only the resistor, the second one with the resistor and a shunt resistor and a third board with the laser diode and a shunt resistor. A DC-DC was realized for the supply while a control unit was realized for the control of the input signals of the driver.Unfortunately, no measurements of the firing unit have been done yet as we are still waiting for the chip to be completed. The DC-DC and the control unit board have been measured and tested. LIDAR application is the most attractive and efficient solution for this market. The challenges of LIDAR application consist in the development of the electronics generating a current pulse of 50A that lasts for less than 5ns. The technical area of this activity is fully autonomous self-driving car, and in particular what helps an autonomous vehicle to understand the world around it.

Ongoing research studying the underlying mechanism and prevalence of Persistent Inward Currents (PICs) has posed a challenge to the conventional view that the firing rate of a motor unit is proportional to the amount of synaptic input it receives. Near the time of human motor unit recruitment during isometric muscle contraction, a sudden steep rise in firing rate is observed, which is suggested to result from rapid triggering of PICs, an intrinsic property of motor neurons. In evaluating the time constants associated with these steep rises in firing rate across different contractile speeds, it has been found that the time course of the steep rise is dependent on the time course of muscle contraction. This evidence suggests that the mechanism underlying this steep rise in firing rate is not PIC-associated, but rather depends on an alternate, unknown mechanism.

Gli ultimi anni dell'opera di Le Corbusier si presentano come i più controversi, offrendo un panorama che spazia dalla realizzazione alla disillusione, dall'incomprensione al riconoscimento internazionale. La tesi affronta quest'articolata produzione sotto molteplici punti di vista, cercando di operare una duplice lettura: una sincronica trasversalmente ai vari campi della sua attività, l'altra diacronica rispetto ai singoli temi. Il periodo 1957-1965 è studiato prendendo in considerazione l'opera artistica, gli scritti, la teoria urbanistica, i progetti non realizzati e l'architettura. In particolare, oggetto di grande attenzione è il "metodo operativo" di Le Corbusier: dall' idea all'architettura. Entrano in gioco, in questa fase, documenti inediti ed interviste ad allievi ed ex-collaboratori, tra i quali: Roger Aujame, Fernand Gardien, José Oubrerie, Claude Parent, Robert Rebutato, André Wogenscky, Dominique Claudius-Petit, fils d'Eugène Claudius-Petit. Particolare attenzione è data alle architetture di Firminy, inquadrate come un possibile frammento della sua urbanistica. La Maison de la Culture, lo stade, l'Unité d'Habitation e l'église de Saint-Pierre sono lette analiticamente: dall'idea originaria all'iter di elaborazione in atelier, dal cantiere alla realizzazione; ed oltre, affrotando la problematica vita di questi edifici dopo il completamento, i diversi interventi di restauro condotti ed in corso, ed i progetti futuri. In particolare, il completamento, i diversi interventi di restauro condotti ed in corso, ed i progetti futuri. In particolare, il completamento dell'église de Saint-Pierre è stato seguito in tempo reale, tra il 2003 e il 2006, a contatto con i progettisti, il cantiere e le imprese<br>Les derniers ans de l'oeuvre de Le Corbusier sont parmi les plus controversé de sa vie, y sont mélangés indissolublement: accomplissement et désillusion, incompréhension et célébrité. La thèse étudie cette production si articulée à partir de deux modalités d'analyse: une synchronique, transversalement aux différents domaines de son activité, l'autre diachronique par rapport à chaque thème de recherche. La période 1957-1965 est étudiée sous multiples points de vue: l'oeuvre plastique, les livres, les théories d'urbanisme, les projets réalisés et non. Dans cette complexité, l'étude de la "méthode de travail" de Le Corbusier s'est avérée être un passage décisif pour comprendre l'évolution qui conduit de l'idée à l'architecture. Nombreux entretiens avec anciens élèves et collaborateurs de Le Corbusier ont été conduits, notamment avec: Roger Aujame, Fernand Gardien, José Oubrerie, Claude Parent, Robert Rebutato, André Wogenscky, Dominique Claudius-Petit, fils d'Eugène Claudius-Petit. L'ensemble d'architectures de Le Corbusier à Firminy occupe un rôle de premier plan dans l'étude, soit sur le plan d'urbanisme, soit du point de vue architecturale. La Maison de la Culture, le Stade, l'Unité d'Habitation et l'église de Saint-Pierre sont étudiés analytiquement: de l'idée originaire à l'iter d'élaboration en atelier, du chantier à l'oeuvre réalisée; et, ensuite, la vie du bâtiment, les interventions de restauration et les projets en cours d'étude en 2005-2006. Enfin, une attention particulière a été donnée au projet de l'église de Saint-Pierre, dont l'achèvement a été suivi en "temps réel", entre 2003 et 2006, en liaison étroite avec les architectes, le chantier et les entreprises<br>The last years of Le Corbusier's work are the most debated and controversial of his life, they offer a wide panorama that roved freely from accomplishment to disillusion, from incomprehension to international acknowledgement. The thesis faces this articulated production from multiple points of view trying to make a double reading of his production: one synchronic that embrace crosswise the different domains of his activity, the second diachronic of every single theme research. The period 1957-1965 has been studied considering Le Corbusier's artistic activity, writings, town-planning vision, realized and non-realized architectural projects, focusing particularly on his "operating method": from idea to architecture. Many interesting interviews were conducted during the research, with personalities like: Roger Aujame, Fernand Gardien, José Oubrerie, Claude Parent, Robert Rebutato, André Wogenscky, Dominique Claudius-Petit, fils d'Eugène Claudius-Petit. The thesis focuses particularly on the architectural complex of Firminy which is, after Chandigarh, the most important fragment of Le Corbusier's town-planning teories. The Maison de la Culture, le Stade, the Unité d'Habitation and the Saint-Pierre church are deeply and widely analyzed: from the primary idea throughout all the evolution of the project in atelier, from construction process to achievement; and more after, including restoration projects and future plans for the site. A great attention was pointed to the achievement of the Firminy's Saint Pierre church, which has been followed in "real time", from 2003 to 2006, in connection with architects and the building contractors

碩士<br>國立成功大學<br>醫學工程研究所<br>86<br>AbstractAnalysis of single motor unit (MU) discharge patterns provides an understanding of the neurophysiologic basis for quantifying the motor control ability. The aim of this research is to apply the surface motor unit action potentials (MUAPs) measured with noninvasive multielectrode for studying the firing characteristics of stroke, neuropathy, myopathy, and healthy volunteers.To investigate the firing rate variation, the measures of singular value decomposition (SVD), joint interval histogram (JIH), and autoregessive model (AR), derived from interpulse interval (IPI) train, were adopted in this research. This study first verifies the JIH parameters, including slope and area obtained from the AR model of simulated IPI sequences. Our simulation results indicate that the JIH slope reflects the stability of firing sequence and the JIH area indicates the whole firing variation. However, the measurement of SVD slope is too sensitive to the data distribution which is discarded in later clinical studies. Furthermore, this study extends the JIH representation to the second-order AR model. For second-order AR model, the firing characteristics can be observed from the location of poles, in terms of radius and phasic angle in z- plane. The phasic angle of the dominated pole, i.e. with larger radius, can be used to quantify the firing stability. An IPI sequence with larger radian of phasic angle indicates better controllability and vice versus.For each of the recruited subjects, sessions of the electromyographic (EMG) signal from the first dorsal interosseus (1st DI) during voluntary and isometric contraction were recorded. A multistage approach, including spatial filtering for peak localization and spatial decomposition for overlapping MUAPs, was utilized for the MU activity analysis of stroke patients. From limited numbers of clinical cases, the changes of firing characteristics of stroke patient, a upper motor neuron disease, significantly differ from the normal mainly in JIH slope indicating lower firing stability. However, the subjects with neuropathy and myopathy have higher firing variation in comparison with that of normal subjects. Our results indicate that the extracted parameters of the JIH ellipse as well as AR model can provide quantitative assessment for motor control ability in stroke patients.

The aim of this study was to determine motor unit firing patterns during ischemic versus non-ischemic sustained submaximal isometric contractions of the tibialis anterior muscle. 10 healthy adults attended two experimental sessions approximately 48 hours apart. Both sessions were identical except that the fatigue task in one was performed with a pressure cuff placed above the knee and inflated to 180 mm Hg. Three 5s maximum voluntary contractions (MVCs) were performed prior to and after the fatigue task. Each participant held a target force of 20% MVC until endurance time (peak-to-peak tremor amplitude exceeded 5% MVC). Single motor unit firing rates (11 non ischemic, 9 ischemic) were recorded with intramuscular fine wire electrodes. Mean interspike intervals over 5s time bins were calculated at every 5% endurance time. The endurance time for the ischemic (3.7 ± 0.58 min) fatigue task was significantly (p<0.001) shorter than the non-ischemic (9.5 ± 0.57 min) task. There was no significant difference in mean motor unit firing rates between the two conditions (p=0.883). Within both tests, there was a significant decline in firing rate (ischemic initial: 12.95 ± 0.71 Hz, minimum: 11.41 ± 0.81 Hz, p=0.023; non-ischemic initial: 13.13 ± 0.87 Hz, minimum: 11.15 ± 0.48 Hz, p=0.012). The time to minimum firing rate was significantly (p<0.001) less in the ischemic (1.29 ± 0.2 min) compared to non-ischemic (3.14 ± 0.23 min) condition. Muscle ischemia significantly reduced endurance time and the time to minimum firing rate. However, there were no differences in average motor unit firing rates between the two conditions across the relative phases of endurance time.<br>text