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‣ Restricted stimulus control in stimulus control shaping with a capuchin monkey

Brino,Ana Leda de Faria; Galvão,Olavo de Faria; Barros,Romariz da Silva; Goulart,Paulo Roney Kilpp; McIlvane,William J.
Fonte: Pontificia Universidade Católica do Rio de Janeiro; Universidade de Brasília; Universidade de São Paulo Publicador: Pontificia Universidade Católica do Rio de Janeiro; Universidade de Brasília; Universidade de São Paulo
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/06/2012 Português
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Teaching the first instances of arbitrary matching-to-sample to nonhumans can prove difficult and time consuming. Stimulus control relations may develop that differ from those intended by the experimenter-even when stimulus control shaping procedures are used. We present, in this study, efforts to identify sources of shaping program failure with a capuchin monkey. Procedures began with a baseline of identity matching. During subsequent shaping trials, compound comparison stimuli had two components-one identical to and another different from the sample. The identical component was eliminated gradually by removing portions across trials (i.e., subtracting stimulus elements). The monkey performed accurately throughout shaping. At a late stage in the program, probe tests were conducted: (1) arbitrary matching trials that had all elements of the identical comparison removed and (2) other trials that included residual elements. During the test, the monkey performed at low levels on the former trials and higher levels on the latter. These results suggested that higher accuracy was due merely to continued control by the residual elements: the target arbitrary matching relations had not been learned. Thus, it appears that procedures that gradually transform identity matching baselines into arbitrary matching can fail by inadvertently shaping restricted control by residual elements. Subsequent probes at the end of the shaping series showed a successful transfer of stimulus control from identity to arbitrary matching after further programming steps apparently overcame the restricted stimulus control.

‣ Shaping Inputs to Reduce Vibration in Flexible Space Structures

Chang, Kenneth W.
Fonte: MIT - Massachusetts Institute of Technology Publicador: MIT - Massachusetts Institute of Technology
Formato: 132 p.; 19413117 bytes; 7151972 bytes; application/postscript; application/pdf
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Future NASA plans to launch large space strucutres solicit the need for effective vibration control schemes which can solve the unique problems associated with unwanted residual vibration in flexible spacecraft. In this work, a unique method of input command shaping called impulse shaping is examined. A theoretical background is presented along with some insight into the methdos of calculating multiple mode sequences. The Middeck Active Control Experiment (MACE) is then described as the testbed for hardware experiments. These results are shown and some of the difficulties of dealing with nonlinearities are discussed. The paper is concluded with some conclusions about calculating and implementing impulse shaping in complex nonlinear systems.

‣ Noise shaping techniques for analog and time to digital converters using voltage controlled oscillators

Straayer, Matthew A. Z. (Matthew Allen Zornig)
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 181 p.
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Advanced CMOS processes offer very fast switching speed and high transistor density that can be utilized to implement analog signal processing functions in interesting and unconventional ways, for example by leveraging time as a signal domain. In this context, voltage controlled ring oscillators are circuit elements that are not only very attractive due to their highly digital implementation which takes advantage of scaling, but also due to their ability to amplify or integrate conventional voltage signals into the time domain. In this work, we take advantage of voltage controlled oscillators to implement analog- and time-to-digital converters with first-order quantization and mismatch noise-shaping. To implement a time-to-digital converter (TDC) with noise-shaping, we present a oscillator that is enabled during the measurement of an input, and then disabled in between measurements. By holding the state of the oscillator in between samples, the quantization error is saved and transferred to the following sample, which can be seen as first-order noise-shaping in the frequency domain. In order to achieve good noise shaping performance, we also present key details of a multi-path oscillator topology that is able to reduce the effective delay per stage by a factor of 5 and accurately preserve the quantization error from measurement to measurement. An 11-bit...

‣ Collimation of electrons via three-dimensional spatial intensity shaping of laser focal volume

Brijesh, Prithviraj ; Meyerhofer, David D. ; Zuegel, Jonathan D.
Fonte: University of Rochester Publicador: University of Rochester
Tipo: Tese de Doutorado Formato: Number of Pages:xiii, 189 leaves
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Thesis (Ph. D.)--University of Rochester. Dept. of Physics and Astronomy, 2010.; Controlling the physics of laser-matter interactions depends on the properties of matter and the characteristic parameters of the laser beam. The dynamics of electrons in the focus of a laser pulse is governed by the spatial intensity profile. The time-averaged ponderomotive force arising from the inhomogeneities in the focal intensity distribution leads to the ejection of a diverging bunch of electrons. This research deals with reducing the divergence angle of the ejected electrons by spatially shaping the three-dimensional focal distribution of a high-intensity laser. A novel laser focus with a centrally peaked transverse focal intensity, transforming into an annular distribution along the laser-propagation direction, has been ex- perimentally demonstrated. The longitudinal profile of such a shaped laser focal volume is approximately in the form of a "horseshoe". The horseshoe focus was re- alized experimentally by an incoherent, coaxial combination of Laguerre-Gaussian and Gaussian modes generated from segmented optical elements. A beam-shaping optical system consisting of reflective segmented optical elements was designed, custom fabricated and fielded on a 10 J...

‣ Channel Estimation and Signal Detection for Multi-Carrier CDMA Systems with Pulse-Shaping Filter

Borran, Mohammad Jaber; Varshney, Prabodh; Vilpponen, Hannu; Papadimitriou, Panayiotis; Borran, Mohammad Jaber; Varshney, Prabodh; Vilpponen, Hannu; Papadimitriou, Panayiotis
Fonte: Universidade Rice Publicador: Universidade Rice
Tipo: Conference paper
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Conference paper; We consider the problem of digital communication in a fading environment using the Multi-Carrier CDMA technology. By incorporating the effect of the pulse-shaping filter in the channel estimation and signal detection modules, we develop new estimator and detector structures which significantly outperform the commonly used time-domain equalizers and matched filter detector. Our simulation results demonstrate the elimination of some of the error floors which one would experience if usual time-domain techniques were used to cancel the effect of nonideal pulse-shaping filter.

‣ Not Just a Matter of Time: Field Differences and the Shaping of Electronic Media

Kling, Rob; McKim, Geoffrey
Fonte: Rob Kling Center for Social Informatics Publicador: Rob Kling Center for Social Informatics
Tipo: Trabalho em Andamento Formato: 10176 bytes; 95696 bytes; image/jpeg; text/html
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The shift towards the use of electronic media in scholarly communication appears to be an inescapable imperative. However, these shifts are uneven, both with respect to field and with respect to the form of communication. Different scientific fields have developed and use distinctly different communicative forums, both in the paper and electronic arenas, and these forums play different communicative roles within the field. One common claim is that we are in the early stages of an electronic revolution, that it is only a matter of time before other fields catch up with the early adopters, and that all fields converge on a stable set of electronic forums. A social shaping of technology (SST) perspective helps us to identify important social forces – centered around disciplinary constructions of trust and of legitimate communication – that pull against convergence. This analysis concludes that communicative plurality and communicative heterogeneity are durable features of the scholarly landscape, and that we are likely to see field differences in the use of and meaning ascribed to communications forums persist, even as overall use of electronic communications technologies both in science and in society as a whole increases.; Indiana University

‣ The role of the Army National Guard in strategic shaping

Hutchinson, Andrew F.
Fonte: Monterey, California ; Naval Postgraduate School Publicador: Monterey, California ; Naval Postgraduate School
Tipo: Tese de Doutorado Formato: xii, 63 p.;28 cm.
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This thesis asks whether the Army National Guard is a capable instrument for strategically shaping the post-Cold War environment to meet United States foreign policy objectives. Further, it examines foreign policy and military benefits of Guard participation in strategic shaping missions. It focuses on the National Guard State Partnership Program (SPP) and the NATO partnership for Peace (PfP) program, although it also refers to National Guard peace operations deployments to Bosnia. The thesis provides background on SPP and PfP and discusses assets the National Guard possesses for strategic shaping, including force structure, expertise, and institutional culture. It addresses the effects strategic shaping missions have on the National Guard's traditional dual missions of providing a disciplined force ready to respond to local and state emergencies and providing properly trained and equipped units for mobilization in response to war and national emergencies. This thesis also compares and contrasts two similar case studies of strategic shaping: a current study of the SPP Partner Challenge 1999 and the NATO PfP Baltic Challenge 1998 exercises. The case studies illustrate capabilities and benefits of the National Guard in strategic shaping. Finally...

‣ Shaping Europe : France, Germany, and embedded bilateralism from the Elysée Treaty to twenty-first century politics

KROTZ, Ulrich; SCHILD, Joachim
Fonte: Oxford University Press Publicador: Oxford University Press
Tipo: Livro
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France and Germany have played a pivotal role in the history and politics of European integration. Yet, paradoxically, a study that systematically investigates the interrelated reality of Franco-German bilateralism and multilateral European integration has been conspicuously lacking. Formulating an approach the authors call "embedded bilateralism", this book offers exactly that. It scrutinizes in empirical and historical detail the bilateral Franco-German order and France and Germany's joint role in shaping Europe over the past half century. The book addresses two key questions regarding France and Germany in Europe from the Elysee Treaty to the twenty-first century: Why have France and Germany continued to hang together in an especially tight relationship for over five decades amidst frequently dramatic domestic change, lasting differences, and fundamental international transformation? And why has the joint Franco-German impact on shaping Europe's polity and European policies, while fundamental, proved so uneven across political domains and time? In answer to the first question, Shaping Europe argues that the actions and practices of the Franco-German order-its regularized bilateral intergovernmentalism, symbolic acts and practices...

‣ Shaping Europe : France, Germany, and embedded bilateralism from the Elysée Treaty to twenty-first century politics

KROTZ, Ulrich; SCHILD, Joachim
Fonte: Instituto Universitário Europeu Publicador: Instituto Universitário Europeu
Tipo: Livro
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This is a revised paperback version of 9780199660087 published in 2013 - http://hdl.handle.net/1814/25315. Contains new and revised materials.; France and Germany have played a pivotal role in the history and politics of European integration. Yet, paradoxically, a study that systematically investigates the interrelated reality of Franco-German bilateralism and multilateral European integration has been conspicuously lacking. Formulating an approach the authors call "embedded bilateralism", this book offers exactly that. It scrutinizes in empirical and historical detail the bilateral Franco-German order and France and Germany's joint role in shaping Europe over the past half century. The book addresses two key questions regarding France and Germany in Europe from the Elysée Treaty to the twenty-first century: Why have France and Germany continued to hang together in an especially tight relationship for over five decades amidst frequently dramatic domestic change, lasting differences, and fundamental international transformation? And why has the joint Franco-German impact on shaping Europe's polity and European policies, while fundamental, proved so uneven across political domains and time? In answer to the first question, Shaping Europe argues that the actions and practices of the Franco-German order-its regularized bilateral intergovernmentalism...

‣ A GEOMETRIC APPROACH TO ENERGY SHAPING

Gharesifard, BAHMAN
Fonte: Quens University Publicador: Quens University
Tipo: Tese de Doutorado Formato: 666735 bytes; application/pdf
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In this thesis is initiated a more systematic geometric exploration of energy shaping. Most of the previous results have been dealt wih particular cases and neither the existence nor the space of solutions has been discussed with any degree of generality. The geometric theory of partial differential equations originated by Goldschmidt and Spencer in late 1960s is utilized to analyze the partial differential equations in energy shaping. The energy shaping partial differential equations are described as a fibered submanifold of a $ k $-jet bundle of a fibered manifold. By revealing the nature of kinetic energy shaping, similarities are noticed between the problem of kinetic energy shaping and some well-known problems in Riemannian geometry. In particular, there is a strong similarity between kinetic energy shaping and the problem of finding a metric connection initiated by Eisenhart and Veblen. We notice that the necessary conditions for the set of so-called $ \lambda $-equation restricted to the control distribution are related to the Ricci identity, similarly to the Eisenhart and Veblen metric connection problem. Finally, the set of $ \lambda $-equations for kinetic energy shaping are coupled with the integrability results of potential energy shaping. The procedure shows how a poor design of closed-loop metric can make it impossible to achieve any flexibility in the character of the possible closed-loop potential function. The integrability results of this thesis have been used to answer some interesting questions about the energy shaping. In particular...

‣ Prompting and stimulus shaping procedures for teaching visual-motor skills to retarded children.

Mosk, M D; Bucher, B
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em //1984 Português
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Stimulus shaping appears to be a highly successful way to teach discrimination skills. In stimulus shaping, the topographical configuration of the stimuli is gradually changed over trials so that discrimination is at first easy, and then gradually more difficult. Stimulus shaping procedures might also be effective for training visual-motor tasks. Two experiments were conducted to assess the relative effectiveness of stimulus shaping and "traditional" prompting procedures. Pegboard skills were trained in Experiment 1. In Experiment 2 a self-care skill was trained, in which children learned to hang a toothbrush or a washcloth on a specific hook. Six low-functioning retarded children were studied in each experiment, using a within-subject alternating treatments design. Each participant received concurrent training on two related tasks, using stimulus shaping for one and a standard prompting procedure for the other. Training with the stimulus shaping procedure required less training time to criterion, always resulted in fewer errors, always required fewer and less intrusive therapist's prompts, and always resulted in greater density of reinforcement. These results demonstrate the value of stimulus shaping strategies for training visual-motor skills.

‣ Brain-computer interface: proposal of a shaping-based training

Silva-Sauer,Leandro da; Valero-Aguayo,Luis; Velasco-Álvarez,Francisco; Ron-Angevín,Ricardo; Sancha-Ros,Salvador
Fonte: SBEB - Sociedade Brasileira de Engenharia Biomédica Publicador: SBEB - Sociedade Brasileira de Engenharia Biomédica
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/06/2013 Português
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INTRODUCTION: Persons affected by certain motor disabilities such as amyotrophic lateral sclerosis can evolve with important motor and speech difficulties in communication. A BCI (Brain Computer Interface) is a system that allows interaction between the human brain and a computer, permitting the user to control a communication channel through his or her brain activity. It is based on the analysis and processing of electroencephalographic (EEG) signals to generate control commands. The present study focuses on the subjects' capability to improve the way they learn to control a BCI system. METHODS: Two training procedures were compared: standard and progressive shaping response. Six volunteers participated in a reversal single-subject ABAC design. RESULTS: The study showed that both procedures are equally effective in producing a differential responding in the EEG signals, with no significant differences between them. Nevertheless, there were significant differences when distinguishing two neuronal responses (relax state and hand-movement imagination). Also, in the analysis of individual signals, an adaptive process for the shaping process and a lower error rate in the idle response appeared. CONCLUSION: Both proposed training procedures...

‣ Constellation Shaping for Bit-Interleaved LDPC Coded APSK

Valenti, Matthew C.; Xiang, Xingyu
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 10/07/2012 Português
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An energy-efficient approach is presented for shaping a bit-interleaved low-density parity-check (LDPC) coded amplitude phase-shift keying (APSK) system. A subset of the interleaved bits output by a binary LDPC encoder are passed through a nonlinear shaping encoder whose output is more likely to be a zero than a one. The "shaping" bits are used to select from among a plurality of subconstellations, while the unshaped bits are used to select the symbol within the subconstellation. Because the shaping bits are biased, symbols from lower-energy subconstellations are selected more frequently than those from higher-energy subconstellations. An iterative decoder shares information among the LDPC decoder, APSK demapper, and shaping decoder. Information rates are computed for a discrete set of APSK ring radii and shaping bit probabilities, and the optimal combination of these parameters is identified for the additive white Gaussian noise (AWGN) channel. With the assistance of extrinsic-information transfer (EXIT) charts, the degree distributions of the LDPC code are optimized for use with the shaped APSK constellation. Simulation results show that the combination of shaping, degree-distribution optimization, and iterative decoding can achieve a gain in excess of 1 dB in AWGN at a rate of 3 bits/symbol compared with a system that does not use shaping...

‣ Potential-Based Shaping and Q-Value Initialization are Equivalent

Wiewiora, E.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 26/06/2011 Português
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Shaping has proven to be a powerful but precarious means of improving reinforcement learning performance. Ng, Harada, and Russell (1999) proposed the potential-based shaping algorithm for adding shaping rewards in a way that guarantees the learner will learn optimal behavior. In this note, we prove certain similarities between this shaping algorithm and the initialization step required for several reinforcement learning algorithms. More specifically, we prove that a reinforcement learner with initial Q-values based on the shaping algorithm's potential function make the same updates throughout learning as a learner receiving potential-based shaping rewards. We further prove that under a broad category of policies, the behavior of these two learners are indistinguishable. The comparison provides intuition on the theoretical properties of the shaping algorithm as well as a suggestion for a simpler method for capturing the algorithm's benefit. In addition, the equivalence raises previously unaddressed issues concerning the efficiency of learning with potential-based shaping.

‣ Waveform Shaping of Sonar Transducers for Improving the Vertical Resolution in Sub-bottom Sediments Profiling

Cobo, Pedro; Ranz Guerra, Carlos; Fernández, Alejandro; Anthony, David K.; Siguero, Manuel
Fonte: Springer Publicador: Springer
Tipo: Artículo Formato: 22195 bytes; application/pdf
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Final full-text version of the paper available at SpringerLink: http://dx.doi.org/10.1007/s11001-005-3709-6.; Vertical resolution is of fundamental importance in sonar exploration and is directly related to the duration of the acoustic pulse generated by the transducer. The shorter the radiated pulse, the higher the vertical resolution. Many sub-bottom profiling sonar systems use piezoelectric transducers because they are reversible and well understood. Piezoelectric projectors are normally resonant transducers, which are intrinsically narrowband. A piezoelectric transducer is usually driven by a tone-burst. However, it is possible to use Fourier techniques to find a pre-compensated electrical driving function so that the transducer radiates a prescribed wider band acoustic waveform. This technique can be applied to synthesize zero-phase cosine-magnitude, Gaussian, and bionic pulses, with a conventional sandwich transducer. Zero-phase cosine-magnitude waveforms provide minimum length pulses (and therefore maximum resolution) within a prescribed frequency band.The aim of this paper is to illustrate the synthesis of wideband acoustic pulses using an underwater piezoelectric projector. The conventional acoustic waveform radiated when a Tonpiltz transducer is transiently excited using a “click” and allows its frequency response function to be measured. This function is used to design the electrical signal which then drives the transducer so that it radiates the shortest pulse compatible with its mechanical response. The significant resolution enhancement of the waveform shaping process is illustrated by its application to a sediment wedge model.; Part of this work has been funded by MCYT (Spain) through Grant No. DPI2001-1613-C02-01.; Peer reviewed

‣ Novel Nonlinear Microscopy Techniques Based on Femtosecond Laser Pulse Shaping and Their Applications

Li, Baolei
Fonte: Universidade Duke Publicador: Universidade Duke
Tipo: Dissertação
Publicado em //2013 Português
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Nonlinear optical microscopy serves as a great tool for biomedical imaging due to its high resolution, deep penetration, inherent three dimensional optical sectioning capabilities and superior performance in scattering media. Conventional nonlinear optical microscopy techniques, e.g. two photon fluorescence and second harmonic generation, are based on detecting a small light signal emitted at a new wavelength that is well separated from the excitation light. However, there are also many other nonlinear processes, such as two-photon absorption and self-phase modulation, that do not generate light at new wavelengths and that have not been extensively explored for imaging. This dissertation extends the accessible mechanisms for contrast to the later nonlinear optical processes by combining femtosecond laser pulse shaping and homodyne detection. We developed a rapid pulse shaper with a relatively simple and compact instrument design that modifies the spectrum of individual laser pulses from an 80 MHz mode-locked laser. The pulse shaper enables simultaneous two-photon absorption and self-phase modulation imaging of various nanoparticles in-vitro with high sensitivity. We also applied this imaging technique to study the nonlinear optical response in graphene. Because our technology detects the nonlinear signature encoded within the laser pulse itself...

‣ Beam Shaping by a Periodic Structure of Left-handed Slabs

Shadrivov, Ilya; Sukhorukov, Andrey; Kivshar, Yuri
Fonte: American Physical Society Publicador: American Physical Society
Tipo: Conference paper
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A study was conducted on the properties of a periodic structure, consisting of the layers of a LH material of the width a, separated by right handed (RH) layers of the width b. Such a system can be regarded as an array of "perfect" lenses with the variation of the refractive index in one structural period. This paper analyzes the transmission propetis of a layered structure consisting of the slabs of positive and negative refractive inde materials and demonstrate the unique properties of the beam propagation and shaping.

‣ Iterative Viterbi Decoding, Trellis shaping and Multilevel Structure for High-Rate Parity-Concatenated TCM

Wang, Q; Wei, L; Kennedy, Rodney
Fonte: Institute of Electrical and Electronics Engineers (IEEE Inc) Publicador: Institute of Electrical and Electronics Engineers (IEEE Inc)
Tipo: Artigo de Revista Científica
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We define and apply a new algorithm called the iterative Viterbi decoding algorithm (IVA) to decode a high-rate parity-concatenated TCM system in which a trellis code is used as the inner code and a simple parity-check code is used as the outer code. With trellis shaping, the IVA can achieve a performance 1.25 dB away from the Shannon limit at a BER of 3 × 10-5 with low complexity. By augmenting the system with a binary BCH code, the error floor can be reduced to 10-9 with very little additional cost.

‣ Weight optimisation in H infinity loop-shaping

Lanzon, Alexander
Fonte: Pergamon-Elsevier Ltd Publicador: Pergamon-Elsevier Ltd
Tipo: Artigo de Revista Científica
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An optimisation problem is introduced which integrates a number of steps of the standard H∞ loop-shaping design procedure. This optimisation problem maximises the robust stability margin over allowable loop-shaping weights while ensuring that the result

‣ A Combined Application of H ∞ Loop Shaping and μ - Synthesis to Control High-Speed Flywheels

Lanzon, Alexander; Tsiotras, Panagiotis
Fonte: Institute of Electrical and Electronics Engineers (IEEE Inc) Publicador: Institute of Electrical and Electronics Engineers (IEEE Inc)
Tipo: Artigo de Revista Científica
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The development of robust controllers for high-speed flywheel rotors supported on active magnetic bearings (AMBs) has been extensively studied over the past decade. Such flywheels can be used as energy momentum wheels (EMWs) onboard spacecraft, and pose a challenging control problem due to their high flexibility, nontrivial parametric uncertainty, and rotor-speed dependence. A combined H∞ loop shaping and μ-synthesis approach is used in this paper to design controllers for EMWs supported on AMBs. This combination between these two well-established control methodologies is novel to the design of robust controllers for such systems. H∞ loop shaping guarantees (through the specification of loop-shaping weights) closed-loop performance and robustness to generic unstructured coprime factor uncertainty, whereas robustness to highly directional parametric uncertainty is incorporated through a μ-synthesis design. Furthermore, in order to reduce the computational complexity of the control design and the order of the synthesized controllers, a method is proposed in this paper to reduce the number of states that depend on the rotor speed. The proposed methodology is demonstrated through numerical simulations and experimental results.