The Experts below are selected from a list of 312 Experts worldwide ranked by ideXlab platform
Fadhel M Ghannouchi - One of the best experts on this subject based on the ideXlab platform.
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investigation of input output waveform engineered Continuous Inverse class f power amplifiers
IEEE Transactions on Microwave Theory and Techniques, 2019Co-Authors: Sagar K Dhar, Tushar Sharma, Ramzi Darraji, Damon G Holmes, Suhas Veetil Illath, Vince Mallette, Fadhel M GhannouchiAbstract:An in-depth analysis of the Continuous Inverse Class F power amplifier (PA) accounting for nonlinear input and output active device properties is presented. The analyses show possible ways of exploiting input nonlinearity to improve and maintain PA performance in a broadband operation and propose a flexible source second-harmonic design space which reduces the input matching network (MN) design complexities. Such exploitation of input nonlinearity can also alleviate performance degradation due to dynamic knee behavior of a practical field-effect transistor (FET) in Continuous Inverse Class F PA operation. The analyses are validated with vector load–pull (VLP) measurements and utilized to implement a broadband PA design. High-drain efficiency (DE) over 75% and output power more than 38 dBm are achieved over 0.8–1.4 GHz at constant 3-dB gain compression.
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Investigation of Input–Output Waveform Engineered Continuous Inverse Class F Power Amplifiers
IEEE Transactions on Microwave Theory and Techniques, 2019Co-Authors: Sagar K Dhar, Tushar Sharma, Ramzi Darraji, Damon G Holmes, Suhas Veetil Illath, Vince Mallette, Fadhel M GhannouchiAbstract:An in-depth analysis of the Continuous Inverse Class F power amplifier (PA) accounting for nonlinear input and output active device properties is presented. The analyses show possible ways of exploiting input nonlinearity to improve and maintain PA performance in a broadband operation and propose a flexible source second-harmonic design space which reduces the input matching network (MN) design complexities. Such exploitation of input nonlinearity can also alleviate performance degradation due to dynamic knee behavior of a practical field-effect transistor (FET) in Continuous Inverse Class F PA operation. The analyses are validated with vector load–pull (VLP) measurements and utilized to implement a broadband PA design. High-drain efficiency (DE) over 75% and output power more than 38 dBm are achieved over 0.8–1.4 GHz at constant 3-dB gain compression.
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On the Continuity of Continuous Inverse Class F Power Amplifiers
2018 IEEE MTT-S Latin America Microwave Conference (LAMC 2018), 2018Co-Authors: Sagar K Dhar, Tushar Sharma, Ramzi Darraji, Mohamed Helaoui, Fadhel M GhannouchiAbstract:Broadband and high efficiency operation of power amplifiers (PAs) are highly desirable for smart transmitting radio frequency (RF) front-ends. Among different techniques, Continuous mode harmonic tuned PAs offer attractive solution because of their methodological design procedures. However, the theory of such Continuous mode PAs assumes constant knee voltage operation which varies over operating drain current in a real device. This work examines the performance of Continuous mode Inverse class F PAs considering variable knee voltage which predicts PA performance more accurately of a real device. Analysis shows about 7% output power and efficiency drop from ideal value which is validated with load-pull measurements.
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High efficiency Continuous mode power amplifiers using waveform engineering
Proceedings of 2014 Mediterranean Microwave Symposium (MMS2014), 2014Co-Authors: Tushar Sharma, Ramzi Darraji, Fadhel M GhannouchiAbstract:This paper discusses the design of different broadband Continuous mode power amplifiers (PAs) using waveform engineering. The Continuous mode provides wider design space for the realization of broadband high efficiency PAs by proper tuning of fundamental, second, third and fourth harmonic impedances. This work discusses in detail the process of waveform synthesis for class-J, Continuous class-F and Continuous Inverse class-F PAs, which are the most popular Continuous mode classes. The validation of our analysis is performed using a 10-Watt Gallium Nitride (GaN) device from Cree Inc. Three different PAs are implemented in Advanced Design Systems (ADS). These PAs are operated in Class-J, Continuous class-F and Continuous Inverse class-F, respectively. Distinctive performance in terms of drain efficiency, output power and transducer gain over wide frequency band is exhibited. The operational class of each PA under study is verified depending on the shaping of voltage and current waveforms that are de-embedded at current generator plane of the packaged device.
Karl-hermann Neeb - One of the best experts on this subject based on the ideXlab platform.
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Norm Continuous Unitary Representations of Lie Algebras of Smooth Sections
International Mathematics Research Notices, 2014Co-Authors: Bas Janssens, Karl-hermann NeebAbstract:Let K→X be a smooth Lie algebra bundle over a σ-compact manifold X whose typical fiber is the compact Lie algebra k. We give a complete description of the irreducible bounded (i.e., norm Continuous) unitary representations of the Frechet–Lie algebra Γ(K) of all smooth sections of K, and of the LF-Lie algebra Γ_c(K) of compactly supported smooth sections. For Γ(K), irreducible bounded unitary representations are finite tensor products of so-called evaluation representations, hence in particular finite dimensional. For Γ_c(K), bounded unitary irreducible (factor) representations are possibly infinite tensor products of evaluation representations, which reduces the classification problem to results of Glimm and Powers on irreducible (factor) representations of UHF C^∗-algebras. The key part in our proof is the result that every irreducible bounded unitary representation of a Lie algebra of the form k⊗A, where A is a unital real complete Continuous Inverse algebra, is a finite product of evaluation representations. On the group level, our results cover in particular the bounded unitary representations of the identity component Gau(P)_0 of the group of smooth gauge transformations of a principal fiber bundle P→X with compact base and structure group, and the groups SU_n(A)_0 with A a complete involutive commutative Continuous Inverse algebra.
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Norm Continuous unitary representations of Lie algebras of smooth sections
arXiv: Representation Theory, 2013Co-Authors: Bas Janssens, Karl-hermann NeebAbstract:We give a complete description of the bounded (i.e. norm Continuous) unitary representations of the Fr\'echet-Lie algebra of all smooth sections, as well as of the LF-Lie algebra of compactly supported smooth sections, of a smooth Lie algebra bundle whose typical fiber is a compact Lie algebra. For the Lie algebra of all sections, bounded unitary irreducible representations are finite tensor products of so-called evaluation representations, hence in particular finite-dimensional. For the Lie algebra of compactly supported sections, bounded unitary irreducible (factor) representations are possibly infinite tensor products of evaluation representations, which reduces the classification problem to results of Glimm and Powers on irreducible (factor) representations of UHF C*-algebras. The key part in our proof is the classification of irreducible bounded unitary representations of Lie algebras that are the tensor product of a compact Lie algebra and a unital real Continuous Inverse algebra: every such representation is a finite product of evaluation representations. On the group level, our results cover in particular the bounded unitary representations of the identity component of the group of smooth gauge transformations of a principal fiber bundle with compact base and structure group, and the connected component of the group of special unitary n times n matrices with values in an involutive commutative Continuous Inverse algebra.
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When unit groups of Continuous Inverse algebras are regular Lie groups
arXiv: Functional Analysis, 2012Co-Authors: Helge Glöckner, Karl-hermann NeebAbstract:It is a basic fact in infinite-dimensional Lie theory that the unit group G(A) of a Continuous Inverse algebra A is a Lie group. We describe criteria ensuring that the Lie group G(A) is regular in Milnor's sense. Notably, G(A) is regular if A is Mackey-complete and locally m-convex.
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Lie group extensions associated to projective modules of Continuous Inverse algebras
arXiv: Operator Algebras, 2008Co-Authors: Karl-hermann NeebAbstract:We call a unital locally convex algebra $A$ a Continuous Inverse algebra if its unit group $A^\times$ is open and inversion is a Continuous map. For any smooth action of a, possibly infinite-dimensional, connected Lie group $G$ on a Continuous Inverse algebra $A$ by automorphisms and any finitely generated projective right $A$-module $E$, we construct a Lie group extension $\hat G$ of $G$ by the group $\GL_A(E)$ of automorphisms of the $A$-module $E$. This Lie group extension is a ``non-commutative'' version of the group $\Aut(\V)$ of automorphism of a vector bundle over a compact manifold $M$, which arises for $G = \Diff(M)$, $A = C^\infty(M,\C)$ and $E = \Gamma\V$. We also identify the Lie algebra $\hat\g$ of $\hat G$ and explain how it is related to connections of the $A$-module $E$.
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Lie group extensions associated to projective modules of Continuous Inverse algebras
2008Co-Authors: Karl-hermann NeebAbstract:We call a unital locally convex algebra A a Continuous Inverse algebra if its unit group A ◊ is open and inversion is a Continuous map. For any smooth action of a, possibly infinite-dimensional, connected Lie group G on a Continuous Inverse algebra A by automorphisms and any finitely generated projective right A-module E, we construct a Lie group extension b G of G by the group GLA(E) of automorphisms of the A-module E. This Lie group extension is a "non-commutative" version of the group Aut(V) of automorphism of a vector bundle over a compact manifold M , which arises for G = Di (M), A = C 1 (M,C) and E = V. We also identify the Lie algebra bg of b G and explain how it is related to connections of the A-module E.
Dariu M Gavrila - One of the best experts on this subject based on the ideXlab platform.
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general sum multi agent Continuous Inverse optimal control
International Conference on Robotics and Automation, 2021Co-Authors: Christian Neumeyer, Frans A Oliehoek, Dariu M GavrilaAbstract:Modeling possible future outcomes of robot-human interactions is of importance in the intelligent vehicle and mobile robotics domains. Knowing the reward function that explains the observed behavior of a human agent is advantageous for modeling the behavior with Markov Decision Processes (MDPs). However, learning the rewards that determine the observed actions from data is complicated by interactions. We present a novel Inverse reinforcement learning (IRL) algorithm that can infer the reward function in multi-agent interactive scenarios. In particular, the agents may act boundedly rational (i.e., sub-optimal), a characteristic that is typical for human decision making. Additionally, every agent optimizes its own reward function which makes it possible to address non-cooperative setups. In contrast to other methods, the algorithm does not rely on reinforcement learning during inference of the parameters of the reward function. We demonstrate that our proposed method accurately infers the ground truth reward function in two-agent interactive experiments.1
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Diversity in Action: General-Sum Multi-Agent Continuous Inverse Optimal Control
arXiv: Learning, 2020Co-Authors: Christian Muench, Frans A Oliehoek, Dariu M GavrilaAbstract:Traffic scenarios are inherently interactive. Multiple decision-makers predict the actions of others and choose strategies that maximize their rewards. We view these interactions from the perspective of game theory which introduces various challenges. Humans are not entirely rational, their rewards need to be inferred from real-world data, and any prediction algorithm needs to be real-time capable so that we can use it in an autonomous vehicle (AV). In this work, we present a game-theoretic method that addresses all of the points above. Compared to many existing methods used for AVs, our approach does 1) not require perfect communication, and 2) allows for individual rewards per agent. Our experiments demonstrate that these more realistic assumptions lead to qualitatively and quantitatively different reward inference and prediction of future actions that match better with expected real-world behaviour.
Andreas Zuefle - One of the best experts on this subject based on the ideXlab platform.
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Continuous Inverse ranking queries in uncertain streams
Statistical and Scientific Database Management, 2011Co-Authors: Thomas Bernecker, Hanspeter Kriegel, Nikos Mamoulis, Matthias Renz, Andreas ZuefleAbstract:This paper introduces a scalable approach for Continuous Inverse ranking on uncertain streams. An uncertain stream is a stream of object instances with confidences, e.g. observed positions of moving objects derived from a sensor. The confidence value assigned to each instance reflects the likelihood that the instance conforms with the current true object state. The Inverse ranking query retrieves the rank of a given query object according to a given score function. In this paper we present a framework that is able to update the query result very efficiently, as the stream provides new observations of the objects. We will theoretically and experimentally show that the query update can be performed in linear time complexity. We conduct an experimental evaluation on synthetic data, which demonstrates the efficiency of our approach.
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SSDBM - Continuous Inverse ranking queries in uncertain streams
Lecture Notes in Computer Science, 2011Co-Authors: Thomas Bernecker, Hanspeter Kriegel, Nikos Mamoulis, Matthias Renz, Andreas ZuefleAbstract:This paper introduces a scalable approach for Continuous Inverse ranking on uncertain streams. An uncertain stream is a stream of object instances with confidences, e.g. observed positions of moving objects derived from a sensor. The confidence value assigned to each instance reflects the likelihood that the instance conforms with the current true object state. The Inverse ranking query retrieves the rank of a given query object according to a given score function. In this paper we present a framework that is able to update the query result very efficiently, as the stream provides new observations of the objects. We will theoretically and experimentally show that the query update can be performed in linear time complexity. We conduct an experimental evaluation on synthetic data, which demonstrates the efficiency of our approach.
Sagar K Dhar - One of the best experts on this subject based on the ideXlab platform.
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investigation of input output waveform engineered Continuous Inverse class f power amplifiers
IEEE Transactions on Microwave Theory and Techniques, 2019Co-Authors: Sagar K Dhar, Tushar Sharma, Ramzi Darraji, Damon G Holmes, Suhas Veetil Illath, Vince Mallette, Fadhel M GhannouchiAbstract:An in-depth analysis of the Continuous Inverse Class F power amplifier (PA) accounting for nonlinear input and output active device properties is presented. The analyses show possible ways of exploiting input nonlinearity to improve and maintain PA performance in a broadband operation and propose a flexible source second-harmonic design space which reduces the input matching network (MN) design complexities. Such exploitation of input nonlinearity can also alleviate performance degradation due to dynamic knee behavior of a practical field-effect transistor (FET) in Continuous Inverse Class F PA operation. The analyses are validated with vector load–pull (VLP) measurements and utilized to implement a broadband PA design. High-drain efficiency (DE) over 75% and output power more than 38 dBm are achieved over 0.8–1.4 GHz at constant 3-dB gain compression.
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Investigation of Input–Output Waveform Engineered Continuous Inverse Class F Power Amplifiers
IEEE Transactions on Microwave Theory and Techniques, 2019Co-Authors: Sagar K Dhar, Tushar Sharma, Ramzi Darraji, Damon G Holmes, Suhas Veetil Illath, Vince Mallette, Fadhel M GhannouchiAbstract:An in-depth analysis of the Continuous Inverse Class F power amplifier (PA) accounting for nonlinear input and output active device properties is presented. The analyses show possible ways of exploiting input nonlinearity to improve and maintain PA performance in a broadband operation and propose a flexible source second-harmonic design space which reduces the input matching network (MN) design complexities. Such exploitation of input nonlinearity can also alleviate performance degradation due to dynamic knee behavior of a practical field-effect transistor (FET) in Continuous Inverse Class F PA operation. The analyses are validated with vector load–pull (VLP) measurements and utilized to implement a broadband PA design. High-drain efficiency (DE) over 75% and output power more than 38 dBm are achieved over 0.8–1.4 GHz at constant 3-dB gain compression.
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On the Continuity of Continuous Inverse Class F Power Amplifiers
2018 IEEE MTT-S Latin America Microwave Conference (LAMC 2018), 2018Co-Authors: Sagar K Dhar, Tushar Sharma, Ramzi Darraji, Mohamed Helaoui, Fadhel M GhannouchiAbstract:Broadband and high efficiency operation of power amplifiers (PAs) are highly desirable for smart transmitting radio frequency (RF) front-ends. Among different techniques, Continuous mode harmonic tuned PAs offer attractive solution because of their methodological design procedures. However, the theory of such Continuous mode PAs assumes constant knee voltage operation which varies over operating drain current in a real device. This work examines the performance of Continuous mode Inverse class F PAs considering variable knee voltage which predicts PA performance more accurately of a real device. Analysis shows about 7% output power and efficiency drop from ideal value which is validated with load-pull measurements.