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Dissertations / Theses on the topic 'Feedforward'

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Published: 4 June 2021

Last updated: 11 March 2023

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1

Johansson, Björn. "Feedforward Control in Dynamic Situations." Licentiate thesis, Linköping University, Linköping University, CSE - Cognitive Systems Engineering Laboratory, 2003. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-5690.

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This thesis proposal discusses control of dynamic systems and its relation to time. Although much research has been done concerning control of dynamic systems and decision making, little research exists about the relationship between time and control. Control is defined as the ability to keep a target system/process in a desired state. In this study, properties of time such as fast, slow, overlapping etc, should be viewed as a relation between the variety of a controlling system and a target system. It is further concluded that humans have great difficulties controlling target systems that have slow responding processes or "dead" time between action and response. This thesis proposal suggests two different studies to adress the problem of human control over slow responding systems and dead time in organisational control.

Report code: LiU-Tek-Lic-2003:17.

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Johansson, Björn. "Feedforward control in dynamic situations /." Linköping : Univ, 2003. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-5690.

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3

Smith, Alison M. "A wideband adaptive feedforward amplifier lineariser." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp04/mq24241.pdf.

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4

Khan, Altaf Hamid. "Feedforward neural networks with constrained weights." Thesis, University of Warwick, 1996. http://wrap.warwick.ac.uk/4332/.

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The conventional multilayer feedforward network having continuous-weights is expensive to implement in digital hardware. Two new types of networks are proposed which lend themselves to cost-effective implementations in hardware and have a fast forward-pass capability. These two differ from the conventional model in having extra constraints on their weights: the first allows its weights to take integer values in the range [-3,3] only, whereas the second restricts its synapses to the set {-1,0,1} while allowing unrestricted offsets. The benefits of the first configuration are in having weights which are only 3-bits deep and a multiplication operation requiring a maximum of one shift, one add, and one sign-change instruction. The advantages of the second are in having 1-bit synapses and a multiplication operation which consists of a single sign-change instruction. The procedure proposed for training these networks starts like the conventional error backpropagation procedure, but becomes more and more discretised in its behaviour as the network gets closer to an error minimum. Mainly based on steepest descent, it also has a perturbation mechanism to avoid getting trapped in local minima, and a novel mechanism for rounding off 'near integers'. It incorporates weight elimination implicitly, which simplifies the choice of the start-up network configuration for training. It is shown that the integer-weight network, although lacking the universal approximation capability, can implement learning tasks, especially classification tasks, to acceptable accuracies. A new theoretical result is presented which shows that the multiplier-free network is a universal approximator over the space of continuous functions of one variable. In light of experimental results it is conjectured that the same is true for functions of many variables. Decision and error surfaces are used to explore the discrete-weight approximation of continuous-weight networks using discretisation schemes other than integer weights. The results suggest that provided a suitable discretisation interval is chosen, a discrete-weight network can be found which performs as well as a continuous-weight networks, but that it may require more hidden neurons than its conventional counterpart. Experiments are performed to compare the generalisation performances of the new networks with that of the conventional one using three very different benchmarks: the MONK's benchmark, a set of artificial tasks designed to compare the capabilities of learning algorithms, the 'onset of diabetes mellitus' prediction data set, a realistic set with very noisy attributes, and finally the handwritten numeral recognition database, a realistic but very structured data set. The results indicate that the new networks, despite having strong constraints on their weights, have generalisation performances similar to that of their conventional counterparts.

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5

Shah, Jagesh V. (Jagesh Vijaykumar). "Learning dynamics in feedforward neural networks." Thesis, Massachusetts Institute of Technology, 1995. http://hdl.handle.net/1721.1/36541.

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Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1995.
Includes bibliographical references (leaves 108-115).
by Jagesh V. Shah.
M.S.

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6

Lotter, Paul. "Development of feedforward RF power amplifier." Thesis, Cape Peninsula University of Technology, 2006. http://hdl.handle.net/20.500.11838/2206.

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Thesis (MTech(Electrical Engineering))--Cape Peninsula University of Technology, 2006.
Electronic communication systems have become an integral part of our everyday lives. RF (Radio Frequency) power amplifiers form part of the fundamental building blocks of an electronic communication system. RF power amplifiers can also be one of the major causes of distortion in an electronic communication system. This thesis describes the linearity requirement for a RF power amplifier that is used in a transmitter section of an electronic communication system. Furthermore, five different linearisation techniques are presented and their characteristics compared. Since a power amplifier employing the Feedforward linearisation technique was designed, built and tested, this thesis focuses on the Feedforward technique. The design methods for the various Feedforward components are presented. The measured parameters of the Feedforward linearised amplifier are compared with the measured parameters of a non-linearised amplifier.

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7

Leonard, Julia Anne. "The feedforward control of posture and movement." Thesis, McGill University, 2013. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=114142.

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Goal-directed arm movements performed in the standing position potentially disturb the body's equilibrium as a result of the multi-linked structure of the musculoskeletal system. To compensate for these disturbances and ensure that stability is maintained, the central nervous system (CNS) organizes postural adjustments preceding and accompanying the voluntary movement in a feedforward manner (Massion 1992) using knowledge of the dynamics of the body (Bouisset and Zattara 1981). To date, most studies investigating the control of posture during voluntary movements in humans have focused on either the role of the postural activity preceding the movement or on the temporal structure of these anticipatory postural adjustments (APAs) with respect to the focal movement. As such, detailed knowledge about the spatial organization of postural activity is lacking. Furthermore, it is not clear how posture is coordinated when the goal of a voluntary movement changes online. Therefore, the studies in this thesis were aimed at addressing these questions to develop a greater understanding of the organization of feedforward postural control during voluntary movements. Muscle activity, kinetics and kinematics were recorded as subjects performed unperturbed and perturbed reaching movements to targets located in multiple directions while standing. Feedforward postural control strategies preceding and accompanying the reaching movements were quantified. Characterization of the spatial and temporal patterns of muscle activity and ground reaction forces of postural adjustments preceding reach movements revealed that muscle activity was directionally-tuned to reach direction and forces that were constrained to two principal directions. Also, muscle synergies were able to explain the spatial and temporal variability in postural muscle activity in the period preceding the reaching movements, suggesting that a modular organization of muscle recruitment is adopted for this task. Overall, these strategies are similar to those observed for feedback postural responses, suggesting that the CNS relies on shared neural structures for controlling posture in both modes of control. Lastly, the nature of postural control was examined when reaching movements were perturbed with a shift of the visual target after the reaching movement was initiated. Here, muscle activity in the legs was consistently modulated prior to changes in the muscle activity related to the online correction of the arm trajectory.Taken together, the findings of this thesis provide important insights into how the brain coordinates the control of posture and movement. This work provides a measure of feedforward postural control strategies in healthy, young adults as a first step to understanding how and why deficits in balance control may occur during the execution of voluntary movements in fall-prone individuals.
Les mouvements volontaires effectués dans la position debout peuvent engendrer des perturbations de l'équilibre en raison de la structure complexe du système musculo-squelettique. Pour amorcer ces perturbations et s'assurer que l'équilibre est maintenu, le système nerveux central (SNC) amorce le déplacement du centre de masse (CM) par la mise en jeu d'ajustements posturaux avant et accompagnant les mouvements programmés en mode proactif (Massion 1992) en utilisant des représentations internes du corps et de l'environnement. À ce jour, la majorité des études portant sur le contrôle de la posture lors des mouvements volontaires chez l'homme ont comme but soit l'identification du rôle ou la caractérisation de la structure temporelle de ces ajustements posturaux anticipateurs. Cependant, une connaissance approfondie concernant l'organisation spatiale de l'activité posturale est manquante. De plus, ce n'est pas évident comment la posture est coordonnée lorsque le but du mouvement change après le commencement du mouvement. Ainsi, les études présentées ici ont comme but de répondre à ces questions pour développer une meilleure compréhension de l'organisation centrale de la posture et le mouvement. Les signaux électromyographiques, les forces de réaction au sol et la cinématique tridimensionnelle ont été enregistrés pendant que les sujets effectuaient des mouvements de pointage vers des cibles distinctes dans la position debout. Les stratégies posturales organisées en mode proactif ont été quantifiées sans pertubations et avect des pertubations visuomotrices des movements d'atteinte. La caractérisation de l'organisation spatiale et temporelle de l'éléctromyographie et des forces appliquées au sol ont révélé que l'activité des muscles était biaisée vers la direction de pointage ('directionally-tuned') mais que les forces au sol étaient appliquées dans un nombre de directions limitées ('force constraint strategy'). De plus, la variabilité spatiale et temporelle de l'activité des muscles posturaux était expliquée par les synergies musculaires. Ceci suggère qu'une organisation modulaire est utilisée par le SNC pour faciliter la tâche de contrôle de la posture. Ces stratégies sont similaires à celles observées pour les ajustements posturaux compensatoires (à base de 'feedback' ou rétroaction), ce qui suggère que le SNC dépend des mêmes structures neuronales pour contrôler la posture dans la mode proactif et rétroactif. Par la suite, la nature du signal pour le contrôle de la posture a été examinée lors des mouvements de pointage qui ont été perturbés avec un déplacement de la cible visuelle après que le mouvement ait été commencé. Ici, l'activité musculaire dans les jambes était modulée avant la modulation de l'activité musculaire liée à la correction de la trajectoire du bras. Ensemble, les conclusions de cette thèse fournissent un aperçu important sur la façon dont le cerveau coordonne le contrôle de la posture et du mouvement. Les résultats présentés supportent la conclusion que les commandes centrales pour la posture et le mouvement interagissent dans le SNC, et que les structures neuronales sont partagées pour la posture organisée de façon anticipatoire, ou proactif, et compensatoire. Les stratégies posturales typiques dans les jeunes adultes en santé sont quantifiées et forment une base de données pour la comparaison avec des gens sujets au déséquilibre lors de la performance des mouvements volontaires.

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8

Unar, Mukhtiar Ali. "Ship steering control using feedforward neural networks." Thesis, University of Glasgow, 1999. http://theses.gla.ac.uk/4493/.

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One significant problem in the design of ship steering control systems is that the dynamics of the vessel change with operating conditions such as the forward speed of the vessel, the depth of the water and loading conditions etc. Approaches considered in the past to overcome these difficulties include the use of self adaptive control systems which adjust the control characteristics on a continuous basis to suit the current operating conditions. Artificial neural networks have been receiving considerable attention in recent years and have been considered for a variety of applications where the characteristics of the controlled system change significantly with operating conditions or with time. Such networks have a configuration which remains fixed once the training phase is complete. The resulting controlled systems thus have more predictable characteristics than those which are found in many forms of traditional self-adaptive control systems. In particular, stability bounds can be investigated through simulation studies as with any other form of controller having fixed characteristics. Feedforward neural networks have enjoyed many successful applications in the field of systems and control. These networks include two major categories: multilayer perceptrons and radial basis function networks. In this thesis, we explore the applicability of both of these artificial neural network architectures for automatic steering of ships in a course changing mode of operation. The approach that has been adopted involves the training of a single artificial neural network to represent a series of conventional controllers for different operating conditions. The resulting network thus captures, in a nonlinear fashion, the essential characteristics of all of the conventional controllers. Most of the artificial neural network controllers developed in this thesis are trained with the data generated through simulation studies. However, experience is also gained of developing a neuro controller on the basis of real data gathered from an actual scale model of a supply ship. Another important aspect of this work is the applicability of local model networks for modelling the dynamics of a ship. Local model networks can be regarded as a generalized form of radial basis function networks and have already proved their worth in a number of applications involving the modelling of systems in which the dynamic characteristics can vary significantly with the system operating conditions. The work presented in this thesis indicates that these networks are highly suitable for modelling the dynamics of a ship.

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9

Tebbs, Robert. "Functionality constraints in feedforward neuromorphic learning systems." Thesis, University of Surrey, 1995. http://epubs.surrey.ac.uk/804354/.

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10

Chen, Francis Xinghang. "Modeling human vision using feedforward neural networks." Thesis, Massachusetts Institute of Technology, 2016. http://hdl.handle.net/1721.1/112824.

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Thesis: M. Eng., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, 2016.
This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references (pages 81-86).
In this thesis, we discuss the implementation, characterization, and evaluation of a new computational model for human vision. Our goal is to understand the mechanisms enabling invariant perception under scaling, translation, and clutter. The model is based on I-Theory [50], and uses convolutional neural networks. We investigate the explanatory power of this approach using the task of object recognition. We find that the model has important similarities with neural architectures and that it can reproduce human perceptual phenomena. This work may be an early step towards a more general and unified human vision model.
by Francis Xinghang Chen.
M. Eng.

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11

Smith, Corne J. "Feedforward active noise reduction for aircraft headsets." Thesis, Stellenbosch : Stellenbosch University, 2003. http://hdl.handle.net/10019.1/49761.

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Thesis (MScEng)--University of Stellenbosch, 2003.
ENGLISH ABSTRACT: Active noise reduction (ANR) is a method of cancelling acoustic noise in a defined enclosure. Two methods exist to implement ANR, they are the analog feedback method and the digital feedforward method. Commercial ANR systems employing feedback methods have been around since the 1980's. Feedforward methods have however only become practically implemental with the age of fast real time digital signal processing. In current systems, feedback ANR is used to attenuate broadband noise whilst feedforward methods are used to attenuate narrow band or tonal noise [2]. This thesis investigates feedforward ANR to cancel broadband acoustic noise in aircraft headsets. Different adaptive filters, optimal configuration of adaptive filters and practical limitations to broadband attenuation for headsets are addressed. Results from this thesis show that at least 10dS noise energy attenuation is attainable over a bandwidth of 2.5kHz. A number of areas for further research are also identified.
AFRIKAANSE OPSOMMING: Aktiewe geraas beheer (AGS) is 'n metode om akoestiese geraas te kanselleer in 'n gedefinieerde omgewing. Twee metodes bestaan om AGS te implementeer. Hulle is die analoog terugvoer en digitale vorentoevoer metode. Kommersiële AGS wat die terugvoer metode gebruik is al in gebruik van die 1980's. Vorentoevoer metodes is egter eers sedert vinnige intydse digitale sein prosessering moontlik. In huidige stelsels word terugvoer AGS gebruik vir die attenuasie van wyeband geraas terwyl vorentoevoer metodes gebruik word om nouband of enkel toon geraas te kanselleer [2]. Die tesis ondersoek vorentoevoer AGS om wyeband akoestiese geraas te kanselleer in vliegtuig kopstukke. Verskillende aanpasbare filters, optimale opstelling van aanpasbare filters en praktiese beperkings tot wyeband attenuasie vir kopstukke word ondersoek. Resultate van die tesis wys dat ten minste 10dS geraas energie attenuasie behaal kan word oor 'n bandwydte van 2.5kHz. 'n Aantal areas vir verder navorsing is ook geïdentifiseer.

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Vipperman, Jeffrey S. "Adaptive feedforward control of broadband structural vibration." Thesis, This resource online, 1992. http://scholar.lib.vt.edu/theses/available/etd-12302008-063428/.

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13

Parsons, Kieran John. "Highly efficient broadband linearisation of RF amplifiers for satellite and cellular applications." Thesis, University of Bristol, 1996. http://hdl.handle.net/1983/2ea6d391-5273-4cd6-a3ab-8d8c780affac.

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14

Holter, Erik. "Feedforward for Stabilization of an Ammonia Synthesis Reactor." Thesis, Norwegian University of Science and Technology, Department of Engineering Cybernetics, 2010. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-9118.

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This thesis illustrates different control structures and tries to demonstrate how feedforward control can be used in stabilizing an unstable ammonia reactor with heat integration. The demonstration of feedforward is done under very special circumstances. While feedback control is necessary for stabilization of the reactor system, feedforward control can be used to avoid input constraints which would otherwise make the input saturate and thereby make the system unstable. It turned out that the ammonia reactor was not the best system to apply the feedforward strategies in question. The main reason is a combination of; the existence of the lower (undesired) steady-state operating point (corresponds to extinction of reaction), positive feedback from the heat exchanger and the manipulated variable range of actuation. The reason is that there are trade offs between making more of the (cold stream) mass flow go through the heat exchanger and making the cold stream mass flow get mixed with the reactor flow between the beds at the quench points. Letting more mass flow entering the heat exchanger will reduce the heat exchanger efficiency. Lowering the efficiency means that the hot stream mass flow through the heat exchanger can not liberate enough heat to the cold stream mass flow entering the heat exchanger. As a result of this, the reactor inlet temperature will decrease because of the positive feedback from the heat exchanger. Thus, it does not exist a range of actuation where the system can be stabilized when influenced by disturbance.

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Leong, Cheok Fan. "Approximation theory of multilayer feedforward artificial neural network." Thesis, University of Macau, 2002. http://umaclib3.umac.mo/record=b1446728.

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Coskun, Arslan Hakan. "Stochastic Characterization And Mathematical Analysis Of Feedforward Linearizers." Phd thesis, METU, 2003. http://etd.lib.metu.edu.tr/upload/626721/index.pdf.

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Feedforward is known to be one of the best methods for power amplifier linearization due to its superior linearization performance and broadband stable operation. However feedforward systems have relatively poor power efficiency and are complicated due to the presence of two nonlinear amplifiers and the requirements of amplitude, phase and delay matching within two different loops. In this thesis stochastic characterization of a simple feedforward system with autocorrelation analysis has been presented for Code Division Multiple Access (CDMA) applications taking the amplitude and delay mismatches into consideration. It has been assumed that, the input signal can be represented as Gaussian noise, main and error amplifiers can be modeled with third order AM/AM nonlinearities and there exists no phase mismatch within the loops. Hence closed form expressions, which relate the main channel and distorted adjacent channel power at any point in the feedforward circuitry to the system parameters, have been obtained. Consequently, a mathematical handy tool is achieved towards specifying the circuit parameters rapidly for optimum linearity performance and efficiency. The developed analytical model has been verified by Radio Frequency (RF) and system simulations. An alternative approach towards modeling feedforward systems for arbitrary signals has also been brought into consideration and has been verified with system simulations.

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Batbayar, Batsukh, and S3099885@student rmit edu au. "Improving Time Efficiency of Feedforward Neural Network Learning." RMIT University. Electrical and Computer Engineering, 2009. http://adt.lib.rmit.edu.au/adt/public/adt-VIT20090303.114706.

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Feedforward neural networks have been widely studied and used in many applications in science and engineering. The training of this type of networks is mainly undertaken using the well-known backpropagation based learning algorithms. One major problem with this type of algorithms is the slow training convergence speed, which hinders their applications. In order to improve the training convergence speed of this type of algorithms, many researchers have developed different improvements and enhancements. However, the slow convergence problem has not been fully addressed. This thesis makes several contributions by proposing new backpropagation learning algorithms based on the terminal attractor concept to improve the existing backpropagation learning algorithms such as the gradient descent and Levenberg-Marquardt algorithms. These new algorithms enable fast convergence both at a distance from and in a close range of the ideal weights. In particular, a new fast convergence mechanism is proposed which is based on the fast terminal attractor concept. Comprehensive simulation studies are undertaken to demonstrate the effectiveness of the proposed backpropagataion algorithms with terminal attractors. Finally, three practical application cases of time series forecasting, character recognition and image interpolation are chosen to show the practicality and usefulness of the proposed learning algorithms with comprehensive comparative studies with existing algorithms.

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Ekong, Donald Uwemedimo. "A fault tolerance technique for feedforward neural networks." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/nq24071.pdf.

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Castro, Núñez Milton David. "Feedforward/feedback control of an inverter-based compensator." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape4/PQDD_0019/MQ53134.pdf.

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Octavian, Stan. "New recursive algorithms for training feedforward multilayer perceptrons." Diss., Georgia Institute of Technology, 1999. http://hdl.handle.net/1853/13534.

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Sweet, Cameron. "Optical free space feedforward non-linearity correction system." Thesis, University of Warwick, 2003. http://wrap.warwick.ac.uk/2666/.

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Recent years have seen unprecedented growth in the popularity and deployment of mobile phones. As this continues, so the strain on existing mobile cellular radio network has also increased, leading to the need to investigate new technologies to relieve this pressure. The problem is being further exacerbated by the introduction of the 3rd generation of mobile communications, otherwise known as UMTS (Universal Mobile Telecommunications System), with the aim of offering multimedia services on pocket sized portable receivers. A major cost of the mobile radio network, in terms of both financial and social/environmental aspects, is the need apparent need for more base transceiver stations (BTS), due to the increased number of services, and the density of them. Therefore, judicious use of fewer, but more "intelligent" base stations, thereby reducing the overall system costs, and extra flexibility in the design of mobile cells would be desirable. This can be achieved by having the BTS antennas remotely positioned from the BTS by transmitting the radio signals down an optical fibre or, as in this project, over free space. The main application for this is in densely urban heavy use areas, where there is extensive reuse of both cell and cell cluster. This, along with building shadowing, would require a BTS on every corner, and where extra cell design flexibility would be desirable. Also, in remote rural areas, where various natural features, such as rivers or mountains can cause similar cell design problems, there is a need for this flexibility. The problem with this requirement is that the electrical to optical conversion process, involving a laser diode driver unit, is inherently non-linear, and, unless this is resolved, the desired signal will become unusable due to distortion. To overcome these nonlinearities, a novel correction may be used, based on an optical feedforward correction technique. The prototype system employs off-the-shelf components, and has one Fabry Perot laser diode (FP-LD) providing two signals (via a beam splitter), for a main path and one for the error path loop. The error path signal is detected by a receiver circuit, then mixed with a reference signal to produce a 'pure' error signal, which then modulates the second FP-LD. In contrast with previous fibre feedforward systems, where the two LD outputs are then combined in the optical fibre pre-reception, this system has to combine the signals post-reception. After the main signal and error signal are received and recombined, the non-linearities of the main path are predominantly cancelled by those present in the error path signal, leaving only the desired signal, free of non-linearities.

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Hofer, Daniel G. Sbarbaro. "Connectionist feedforward networks for control of nonlinear systems." Thesis, University of Glasgow, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.390248.

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Ahmad, Jamil. "A novel learning algorithm for feedforward neural network." Thesis, King's College London (University of London), 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.404310.

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Smith, G. Clark II. "Optimum Actuator Grouping in Feedforward Active Control Applications." Thesis, Virginia Tech, 1994. http://hdl.handle.net/10919/36561.

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Previous work has demonstrated the benefit of grouping actuators to increase the controllability of an active control system, without increasing the number of control channels. By driving two or more secondary sources with the same control input, one is also able to reduce the hardware cost and complexity. In this work, a time domain cost function is developed for on-line actuator grouping and active structural acoustic control (ASAC) of a simply-supported beam excited with a broadband disturbance. Three PZT actuators are mounted on the beam structure to control the wavenumber components corresponding to five radiation angles. The propagation angles are selected to represent the total radiated sound power. The point force disturbance is bandlimited random noise which encompasses the first three modes of beam vibration. Actuators are considered grouped when their compensators are equal. Therefore, the cost function presented here incorporates an additional non-quadratic term which penalizes the controller for differences between the feedforward compensator coefficients. The backpropagation neural network algorithm provides the proper procedure to determine the minimum of this cost function. The main disadvantage of using a stochastic gradient technique, while searching the prescribed control surface, is convergence to local minima. In this thesis, a resolution to this problem is suggested which incorporates using a variety of initial conditions. Two initialization conditions are considered: grouping actuators based upon weights determined by converging the filtered-x LMS algorithm and simultaneously grouping and controlling with the compensator weights initialized to small arbitrary numbers. Test cases of heavy and light grouping parameters were evaluated from both initial conditions. The computer simulations demonstrate the ability of this new form of the cost function to group actuators and control the error response with either initial condition. The heavy grouping cases achieved the same one channel control system from both initial conditions. The performance of the one channel solution was 1.5 dB lower than the performance of the ungrouped filtered-x LMS solution. The ability to select the different levels of grouping was demonstrated when the algorithm was initialized with the filtered-x LMS weights and run with light grouping parameters. For this case, the on-line algorithm grouped two actuators, but allowed the third actuator to exist independently. The performance of the two channel control system was only 0.6 dB less than the performance of the filtered-x LMS solution. In all grouping cases investigated, the convergence times of the grouping algorithm were within the same order as for the filtered-x LMS algorithm. The effect of uncorrelated error sensor noise on the actuator groupings is also briefly discussed.
Master of Science

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Lindberg, Martin. "Introducing Gestures: Exploring Feedforward in Touch-Gesture Interfaces." Thesis, Malmö universitet, Fakulteten för kultur och samhälle (KS), 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:mau:diva-23555.

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This interaction design thesis aimed to explore how users could be introduced to the different functionalities of a gesture-based touch screen interface. This was done through a user-centred design research process where the designer was taught different artefacts by experienced users. Insights from this process lay the foundation for an interactive, digital gesture-introduction prototype.Testing said prototype with users yielded this study's results. While containing several areas for improvement regarding implementation and behaviour, the prototype's base methods and qualities were well received. Further development would be needed to fully assess its viability. The user-centred research methods used in this project proved valuable for later ideation and prototyping stages. Activities and results from this project indicate a potential for designers to further explore the possibilities for ensuring the discoverability of touch-gesture interactions. For future projects the author suggests more extensive research and testing using a greater sample size and wider demographic.

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Redpath, Stuart Frederick. "Universal approximation properties of feedforward artificial neural networks." Thesis, Rhodes University, 2011. http://hdl.handle.net/10962/d1015869.

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In this thesis we summarise several results in the literature which show the approximation capabilities of multilayer feedforward artificial neural networks. We show that multilayer feedforward artificial neural networks are capable of approximating continuous and measurable functions from Rn to R to any degree of accuracy under certain conditions. In particular making use of the Stone-Weierstrass and Hahn-Banach theorems, we show that a multilayer feedforward artificial neural network can approximate any continuous function to any degree of accuracy, by using either an arbitrary squashing function or any continuous sigmoidal function for activation. Making use of the Stone-Weirstrass Theorem again, we extend these approximation capabilities of multilayer feedforward artificial neural networks to the space of measurable functions under any probability measure.

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Lartz, Douglas John. "Feedforward temperature control using a heat flux microsensor." Thesis, This resource online, 1993. http://scholar.lib.vt.edu/theses/available/etd-06302009-040309/.

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Uzuegbunam, Nkiruka M. A. "SELF-IMAGE MULTIMEDIA TECHNOLOGIES FOR FEEDFORWARD OBSERVATIONAL LEARNING." UKnowledge, 2018. https://uknowledge.uky.edu/ece_etds/124.

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This dissertation investigates the development and use of self-images in augmented reality systems for learning and learning-based activities. This work focuses on self- modeling, a particular form of learning, actively employed in various settings for therapy or teaching. In particular, this work aims to develop novel multimedia systems to support the display and rendering of augmented self-images. It aims to use interactivity (via games) as a means of obtaining imagery for use in creating augmented self-images. Two multimedia systems are developed, discussed and analyzed. The proposed systems are validated in terms of their technical innovation and their clinical efficacy in delivering behavioral interventions for young children on the autism spectrum.

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Fernández, Redondo Mercedes. "Hacia un diseño óptimo de la arquitectura Multilayer Feedforward." Doctoral thesis, Universitat Jaume I, 2001. http://hdl.handle.net/10803/10374.

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El objetivo de esta Tesis Doctoral ha sido básicamente el de realizar un estudio comparativo sobre los diferentes métodos existentes para resolver diversos aspectos referentes al diseño de la arquitectura de red neuronal Multilayer Feedforward, en problemas de clasificación de redes neuronales.
Los aspectos de diseño de la arquitectura de red neuronal estudiados han sido: codificación de entradas desconocidas, selección de la información de entrada a la red, selección del número de unidades ocultas, influencia en la capacidad de generalización del número de capas ocultas e inicialización de pesos de la red.
Para cada uno de los aspectos se ha realizado un estudio comparativo de los diferentes métodos existentes para resolver dicho problema. Como resultado recomendamos finalmente el uso de los mejores métodos a la hora de realizar una aplicación concreta.
The objective of this Doctoral Thesis was to carry a comparative study on several existent methods in order to solve different aspects of the design of Multilayer Feedforward architecture, in neural networks classification problems.
The aspects of design studied were: handling unknown input information, input selection, selection of the number of hidden units, influence in the generalization capability of the number of hidden layers and weight initialization.
For each one of these aspects, we carried out a comparative study of several existent methods in order to solve the problem. We recommend the use of the best methods in order to develop a concrete application.

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Dumitras, Adriana. "Feedforward neural network design with application to image subsampling." Thesis, University of British Columbia, 1999. http://hdl.handle.net/2429/41445.

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Feedforward artificial neural networks (FANNs), which have been successfully applied to various image processing tasks, are particularly suitable for image subsampling due to their high processing speed. However, the performance of FANNs in image subsampling, which depends on both the FANN topology and the FANN training algorithm, has not been acceptable so far. High performance image subsampling is important in many systems, such as subband decomposition systems, and scalable image and video processing systems. This thesis addresses the design of FANNs with application to image subsampling. More specifically, we focus on both the topological design of FANNs and the training algorithm, so that efficient FANN structures, yielding good performance in image subsampling, are obtained. That is, we aim at obtaining compact FANNs that yield good subsampled versions of the original images, such that if reconstructed, they are as close as possible to the original images. Moreover, we aim at obtaining better performance-speed tradeoffs than those of the traditional lowpass filtering and subsampling methods. First, we propose a design method for FANNs, which leads to compact tridiagonally symmetrical feedforward neural networks (TS—FANNs). Next, in order to address the problem of artifacts that generally appear in the reconstructed images after FANN-based subsampling, we propose a training method for FANNs. When applied to first-order (FOS) and multi-stage first-order (MFOS) image subsampling, the FANNs trained using our method outperform the traditional lowpass filtering and subsampling (LPFS) method, without requiring pre- or post-processing stages. Motivated by our observation that the computational demands of the MFOS process increase approximately linearly with the image size, we then combine the proposed methods and evaluate the performance-complexity tradeoffs of the resulting TS-FANNs in FOS and MFOS. We show that our TS-FANNs-based subsampling has important advantages over subsampling methods based on fully connected FANNs (FC—FANNs) and LPFS, such as significantly reduced computational demands, and the same, or better, quality of the resulting images. The main contributions of this thesis consist of a method for FANN design with tridiagonal symmetry constraints, a training algorithm for FANNs applied to image subsampling, the design and evaluation of the performance-speed tradeoffs of FC—FANNs in image subsampling, and the design and evaluation of the performancespeed tradeoffs of TS—FANNs in image subsampling. The FANN performance in image subsampling is evaluated objectively (using the peak signal-to-noise ratios), subjectively (by visual examination of the subsampled and of the reconstructed images), and in the context of a video coding application. The speed and memory demands of the designed FANN structures are evaluated in terms of the subsampling time and the number of FANN parameters, respectively.
Applied Science, Faculty of
Electrical and Computer Engineering, Department of
Graduate

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31

McPherson, Douglas S. "Ka-band vector modulator for LMCS adaptive feedforward linearizer." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape17/PQDD_0023/MQ27020.pdf.

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Cibere, Joseph John. "Calibration transfer methods for feedforward neural network based instruments." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/NQ63857.pdf.

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Sukhon, Mohammad. "Double-sampled digital-feedforward second-order delta-sigma modulator." Thesis, McGill University, 2009. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=32527.

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A 12-bit 2.8-MHz delta sigma modulator intended for ADSL applications is presented in this thesis. The design process evolved over two stages, namely, a system-level design stage followed by a circuit-level design stage. During the first phase of the design, the systemlevel parameters are selected and analog-circuit specifications are derived. The circuitlevel stage involved the design of analog circuitry such as operational amplifiers capable of meeting the system-level specifications. The circuit design was carried out in 1-V 65- nm CMOS technology. Double-sampling was employed to make the switched-capacitor circuits more power efficient. Input-signal feedforward was used to lower the signal swing at the output of the opamps. Digital input feedforward is used and presented as an alternative to analog input feedforward.
Un modulateur delta sigma 12-bit 2.8-MHz conçu pour des applications ADSL est présenté dans ce mémoire. Le processus de conception est décrit en deux phases: la conception au niveau du système suivie de la réalisation au niveau du circuit. Lors de la première phase, les paramètres du système sont choisis et les spécifications analogiques du circuit sont dérivées. La phase de l'implémentation du circuit impliquait la conception de circuits analogiques tels que amplificateurs opérationnels respectant les spécifications du système. La conception du circuit a été réalisée sur la technologie 1-V 65-nm CMOS. Le doubleéchantillonnage a été employé afin que les circuits de condensateurs-commutés soient plus économiques en terme de puissance. La technique d'action directe (feedforward) a été utilisée sur le signal d'entrée afin de réduire l'amplitude à la sortie des amplificateurs. La technique d'action directe digitale sur le signal d'entrée est utilisée et présentée comme une alternative à son homologue analogique.

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O'Kane, Dominic. "Statistical mechanical studies of autoassociative and feedforward neural networks." Thesis, University of Oxford, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.357443.

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Bennett, David William. "The design and performance of automatically-controlled feedforward amplifiers." Thesis, University of Bristol, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.296590.

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Collins, Simon Andrew. "Multi-axis analog adaptive feedforward cancellation of cryocooler vibration." Thesis, Massachusetts Institute of Technology, 1994. http://hdl.handle.net/1721.1/11940.

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37

Chi, Zi Qiang. "Fuzzy feedback control of piezoelectric actuator with feedforward compensation." Thesis, University of Macau, 2015. http://umaclib3.umac.mo/record=b3335773.

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38

Perez-Minana, Elena. "Nature of the learning algorithms for feedforward neural networks." Thesis, University of Edinburgh, 1997. http://hdl.handle.net/1842/30641.

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The "neural network" model (NN) comprised of relatively simple computing elements, operating in parallel, offers an attractive and versatile framework for exploring a variety of learning structures and processes for intelligent systems. Due to the amount of research developed in the last decade many types of "networks" have been defined. The one of interest here is the "multi-layer perceptron" as it is one of the simplest and it is considered a powerful representation tool whose complete potential has not been adequately exploited and whose limitations need yet to be specified in a formal and coherent framework. This dissertation addresses the theory of generalisation performance and architecture selection for the multi-layer perceptron; a subsidiary aim is to compare and integrate this model with existing data analysis techniques and exploit its potential by combining it with certain constructs from computational geometry creating a reliable, coherent network design process which conforms to the characteristics of a constructive learning algorithm. After discussing in general terms the motivation for this study, the multi-layer perceptron model is introduced and reviewed, along with the relevant supervised training algorithm, ie. backpropagation. In particular, it is argued that a network developed employing this model can in general be trained and designed in a much better way by extracting more information about the domains of interest through the application of certain geometric constructs in a preprocessing stage, specifically by generating the Voronoi Diagram and Delaunay Triangulation of the set of points comprising the training set and once a final architecture which performs appropriately on it has been obtained. Principal Component Analysis is applied to the outputs produced by the units in the network's hidden layer to eliminate the redundant dimensions of this space.

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Arechiga, Austin Podoll. "Sensitivity of Feedforward Neural Networks to Harsh Computing Environments." Thesis, Virginia Tech, 2018. http://hdl.handle.net/10919/84527.

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Neural Networks have proven themselves very adept at solving a wide variety of problems, in particular they accel at image processing. However, it remains unknown how well they perform under memory errors. This thesis focuses on the robustness of neural networks under memory errors, specifically single event upset style errors where single bits flip in a network's trained parameters. The main goal of these experiments is to determine if different neural network architectures are more robust than others. Initial experiments show that MLPs are more robust than CNNs. Within MLPs, deeper MLPs are more robust and for CNNs larger kernels are more robust. Additionally, the CNNs displayed bimodal failure behavior, where memory errors would either not affect the performance of the network, or they would degrade its performance to be on par with random guessing. VGG16, ResNet50, and InceptionV3 were also tested for their robustness. ResNet50 and InceptionV3 were both more robust than VGG16. This could be due to their use of Batch Normalization or the fact that ResNet50 and InceptionV3 both use shortcut connections in their hidden layers. After determining which networks were most robust, some estimated error rates from neutrons were calculated for space environments to determine if these architectures were robust enough to survive. It was determined that large MLPs, ResNet50, and InceptionV3 could survive in Low Earth Orbit on commercial memory technology and only use software error correction.
Master of Science

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Matevosian, Armond. "Hybrid adaptive feedforward control of structures to seismic inputs." Thesis, Virginia Tech, 1996. http://hdl.handle.net/10919/44969.

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The key conclusions of this research are: 1. The EFXLMS algorithm demonstrated superior performance than the FXLMS algorithm during fast adaptive processes, in particular for non-stationary inputs. 2. Good attenuation of the peak. and root-mean-square (rms) values of the structural responses using the hybrid control system were observed for most of the real accelerograms. It was also observed that the hybrid control system always improved the performance of the passive control system. 3. Peak. structural responses during sensor failures were observed to increase, in particular for the failure of the first error sensor. However, the peak. responses during these failures never reached the peak. values obtained by the system with passive control. This demonstrated the ability of the control system to contain the structural responses in light of the error sensor failures. 4. Peak. structural responses during control actuator failures were also observed to increase, in particular for the failure of the fIrst control actuator ADVAI. However, the peak. responses during these failures again never reached the peak. values obtained by the system using passive control. This demonstrated the ability of the control system to contain the structural responses in light of the control actuator failures. 5. The use of the adaptive control showed greater attenuation of the structural responses than that observed using the non-adaptive system. This demonstrated that the adaptive control system corrected for uncertainties and errors in the modeling process.
Master of Science

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Lane, Steven. "Time average feedforward control techniques for time varying systems." Thesis, This resource online, 1994. http://scholar.lib.vt.edu/theses/available/etd-06082009-170722/.

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Davila, Carlos Antonio. "Image super-resolution performance of multilayer feedforward neural networks." Diss., The University of Arizona, 1999. http://hdl.handle.net/10150/284549.

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Super-resolution is the process by which the bandwidth of a diffraction-limited spectrum is extended beyond the optical passband. Many algorithms exist which are capable of super-resolution; however most are iterative methods, which are ill-suited for real-time operation. One approach that has been virtually ignored in super-resolution research is the neural network approach. The Hopfield network has been a popular choice in image restoration applications, however it is also an iterative approach. We consider the feedforward architecture known as a Multilayer Perceptron (MLP), and present results on simulated binary and greyscale images blurred by a diffraction-limited OTF and sampled at the Nyquist rate. To avoid aliasing, the network performs as a nonlinear spatial interpolator while simultaneously extrapolating in the frequency domain. Additionally, a novel use of vector quantization for the generation of training data sets is presented. This is accomplished by training a nonlinear vector quantizer (NLIVQ), whose codebooks are subsequently used in the supervised training of the MLP network using Back-Propagation. The network shows good regularization in the presence of noise.

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Zhu, Mingjuan 1975. "Design of feedforward active ripple filters for power converters." Thesis, Massachusetts Institute of Technology, 1999. http://hdl.handle.net/1721.1/9491.

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Thesis (M.Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1999.
Includes bibliographical references (leaves 76-77).
An active ripple filter is an electronic circuit which cancels or suppresses the ripple current and EMI generated by the power stage of a power converter, thus reducing the passive filtration requirements. This thesis presents the design and evaluation of various current sensing and injection methods for feedforward active filter applications including a Rogowski-Coil sensor, a transformer sensor, a class A injector, and a current transformer based injector. The advantages, tradeoffs, and limitation of each approach are discussed in detail. This thesis also presents the design and evaluation of a prototype feedforword active filter which employs a Rogowski-Coil current sensor and a class A current injector on a 42V /14 V de/de power converter system. Quantitative comparisons between a hybrid passive/active filter and a purely passive filter having the same performance are presented. It is demonstrated that substantial improvements in filter mass and converter transient performance can be achieved using the proposed active ripple filtering method.
by Mingjuan Zhu.
M.Eng.

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Lau, Mian Mian. "Vulnerable Road Users Detection using Convolutional Deep Feedforward Network." Thesis, Curtin University, 2021. http://hdl.handle.net/20.500.11937/83745.

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A new convolutional deep feedforward network (C-DFN) is proposed to detect vulnerable road users at 57.9% misclassification rate using Caltech Dataset. Instead of going deeper, three C-DFN is stacked to achieve 43.4% misclassification rate. Part-based C-DFN further reduces the rate of 42.5% to tackle occlusion problem. In addition, investigation of adaptive activation functions are performed to understand the effect of saturated and non-saturated functions in mitigating the vanishing and exploding gradient issues of neural networks.

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Myoung, Suk Keun. "Low frequency feedforward and predistortion linearization of RF power amplifiers." Columbus, Ohio : Ohio State University, 2006. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1150416616.

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Coue, Dominique Xavier Henri Leon. "Feedforward artificial neural network design utilising subthreshold mode CMOS devices." Thesis, University of Plymouth, 1997. http://hdl.handle.net/10026.1/1633.

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This thesis reviews various previously reported techniques for simulating artificial neural networks and investigates the design of fully-connected feedforward networks based on MOS transistors operating in the subthreshold mode of conduction as they are suitable for performing compact, low power, implantable pattern recognition systems. The principal objective is to demonstrate that the transfer characteristic of the devices can be fully exploited to design basic processing modules which overcome the linearity range, weight resolution, processing speed, noise and mismatch of components problems associated with weak inversion conduction, and so be used to implement networks which can be trained to perform practical tasks. A new four-quadrant analogue multiplier, one of the most important cells in the design of artificial neural networks, is developed. Analytical as well as simulation results suggest that the new scheme can efficiently be used to emulate both the synaptic and thresholding functions. To complement this thresholding-synapse, a novel current-to-voltage converter is also introduced. The characteristics of the well known sample-and-hold circuit as a weight memory scheme are analytically derived and simulation results suggest that a dummy compensated technique is required to obtain the required minimum of 8 bits weight resolution. Performance of the combined load and thresholding-synapse arrangement as well as an on-chip update/refresh mechanism are analytically evaluated and simulation studies on the Exclusive OR network as a benchmark problem are provided and indicate a useful level of functionality. Experimental results on the Exclusive OR network and a 'QRS' complex detector based on a 10:6:3 multilayer perceptron are also presented and demonstrate the potential of the proposed design techniques in emulating feedforward neural networks.

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Warr, Paul. "Octave-band feedforward linearisation for software defined radio receiver amplifiers." Thesis, University of Bristol, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.340270.

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Cattell, Joseph Harry 1977. "Adaptive feedforward cancellation viewed from an oscillator amplitude control perspective." Thesis, Massachusetts Institute of Technology, 2003. http://hdl.handle.net/1721.1/28280.

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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2003.
Includes bibliographical references (p. 335-340).
This thesis presents methods of characterizing the convergence, error, stability, and robustness properties of Adaptive Feedforward Cancellation (AFC) for use on fast tool servos in high-precision turning applications. Previous work has shown that classical control techniques can be used to analyze the stability and robustness of an AFC loop. However, determination of the convergence and error properties of the closed-loop system to changes in the reference or disturbance signal is not an obvious output of these analyses. We have developed a method of viewing AFC from an oscillator amplitude control (OAC) perspective, which provides additional use of classical control techniques to determine the convergence and error properties of the closed-loop system. AFC is a form of repetitive control that can be used to significantly improve periodic trajectory following/disturbance rejection. Fast tool servos used in high-precision turning applications commonly follow periodic trajectories and develop large errors, which usually occur at integer harmonics of the fundamental spindle rotation frequency. We have developed a loop-shaping approach to designing multiple resonator AFC controllers and have implemented this design on a commercially available piezoelectric (PZ) driven FTS using a PC-based digital control system. Our view of Adaptive Feedforward Cancellation from an oscillator amplitude control perspective builds upon previous work in the literature. We use an averaging analysis to simplify the single resonator AFC system into two coupled single-input single-output (SISO) oscillator amplitude control loops and show that by using the correct rotation matrix, these loops are effectively decoupled. This simplification provides the use of classical control techniques to approximate the dynamics of the closedloop output to changes in the amplitude or frequency of the reference/disturbance signal. The simulated and experimental results conform well to our analytical predictions for sufficiently low gain values.
by Joseph Harry Cattell.
S.M.

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49

Batista, Flabio Alberto Bardemaker. "Tecnicas de compensação direta (Feedforward) empregando integradores em conversores PWM." reponame:Repositório Institucional da UFSC, 1996. https://repositorio.ufsc.br/handle/123456789/106435.

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Dissertação (mestrado) - Universidade Federal de Santa Catarina, Florianópolis, 1996.
Made available in DSpace on 2013-12-05T20:31:05Z (GMT). No. of bitstreams: 1 106211.pdf: 5441669 bytes, checksum: d0024da3e333d4d95d9b347661919b23 (MD5) Previous issue date: 1996
Estudo das principais características dos controladores feedforward aplicados a conversores CC-CC. Análise do controladores feedforward convencional, controle integral com reset (One Cycle Control - OCC), controle integral modulado (CIM) e controle ASDTIC (Analog Signal to Discrete Time Interval Converter). Verificação dos seguintes aspectos: formas de onda, princípio de funcionamento, comportamento estático e dinâmico, possibilidade de utilização em conversores que operam em condução descontínua (DCM) e capacidade de rejeição às perturbações de baixa freqüência, sendo esta última característica analisada em maior profundidade. Alguns dos resultados obtidos são verificados em experimentação ou por simulação digital (PSPICE). Implementação de um protótipo utilizando a combinação da malha de feedforward com a malha de realimentação para avaliar o efeito da combinação destas duas malhas na atenuação da ondulação do sinal de saída do conversor.

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Batista, Flabio Alberto Bardemaker. "Técnicas de compensação direta (Feedforward) empregando integradores em conversores PWM." reponame:Repositório Institucional da UFSC, 1996. https://repositorio.ufsc.br/handle/123456789/111756.

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