About

Amr Baz is a Minta Martin Professor, Keystone Professor, and Director of the Smart Materials and Structures Research Center at the Department of Mechanical Engineering, University of Maryland. He holds a Ph.D. from the University of Wisconsin, Madison, obtained in 1973. His research interests focus on active and passive control of vibration and noise, active constrained layer damping, magnetic composites, and acoustic metamaterials. He has contributed significantly to the development of active nonreciprocal metamaterials, eigen-structure control strategies, and energy harvesting using acoustic metamaterials. Professor Baz has been recognized with numerous awards for his research and teaching, including the ASME Adaptive Structures and Material Systems Award, the SPIE Smart Structures and Materials Lifetime Achievement Award, and the University of Maryland Distinguished Teaching-Scholar Award. He is actively involved in editorial roles for several scientific journals related to vibration, acoustics, and smart structures. His work encompasses the development of innovative control strategies and metamaterials with applications in ground platforms, sound absorption, and structural stability. Throughout his career, he has made foundational contributions to the understanding and application of active and nonreciprocal acoustic and mechanical metamaterials, establishing himself as a leading figure in his field.

Research topics

• Computer Science
• Acoustics
• Physics
• Optics
• Telecommunications
• Optoelectronics
• Materials science
• Quantum mechanics

Selected publications

• On the Ziegler destabilization paradox

  Acta Mechanica · 2025-03-25

  article1st authorCorresponding
  PublisherDOI

• Acoustic Black Hole With Functionally Graded Perforated Rings: Modeling and Experimental Performance

  Journal of vibration and acoustics · 2025-06-06 · 2 citations

  articleOpen accessSenior author

  Abstract This article presents a comprehensive theoretical and experimental investigation of a novel class of acoustic black hole (ABH) waveguides that harnesses the functionality of an array of optimally designed functionally graded perforated rings (FGPR). Through this approach, the developed ABH exhibits inherent energy dissipation characteristics derived from the flow through the perforations, which enhances its acoustic absorption behavior, resulting in rapid attenuation of the propagating waves as it traverses the length of the waveguide. Accordingly, this article presents a comsol-based finite element modeling (FEM) approach to predict the behavior of this class of ABH. The model aims to demonstrate the merits of the proposed ABH as an effective means for absorbing sound propagation. Numerical simulations are conducted to showcase the advantages and behavior of the proposed ABH configurations in comparison with the predictions of our previously developed transfer matrix model (TMM). The theoretical predictions of both the FEM and TMM models are validated against experimental results which are collected using manufactured prototypes of the ABH/FGPR that are tested using the ACUPRO impedance tube. Comparisons between the predicted and measured results show close agreements.

  PublisherOA PDFDOI

• Bandgap, dispersion, and non-reciprocal characteristics of an active Willis metamaterial

  The Journal of the Acoustical Society of America · 2025-07-01 · 1 citations

  articleOpen access1st authorCorresponding

  Active Willis metamaterials (AWM) have attracted considerable attention, recently, by virtue of their unique electro-elastic coupling, controllability, and observability characteristics. In this paper, these characteristics are utilized to further demonstrate other unique bandgap, dispersion, and non-reciprocal capabilities that distinguishes them from conventional materials. A one-dimensional example of a piezoelectric-based AWM is presented to demonstrate the tunability of the bandgap and dispersion characteristics during forward and backward propagations. In the selected example, the AWM consists of two dissimilar masses connected by a piezoelectric spring. Lagrange dynamics approach is employed to develop the equations governing the Willis coupling, the piezoelectric coupling, and to reveal the inherent control abilities of the bandgap and dispersion characteristics. With this developed controlled-based structure of the AWM, it is shown that the AWM can simultaneously monitor and control both the physical properties as well as spatial width and the spectral location of the bandgaps while controlling the wave number and acoustical impedance at specific desirable levels. It is envisioned that the developed simple one-dimensional AWM model has revealed more interesting wave propagation and control capabilities which can help investigating more complex configurations of the AWM's.

  PublisherOA PDFDOI

• Acoustic black hole with functionally graded perforated rings and sound absorbing layers: Theory and experiments

  Journal of low frequency noise, vibration and active control · 2025-05-07 · 1 citations

  articleOpen accessSenior authorCorresponding

  This paper presents a theoretical and experimental study of the acoustic characteristics of a class of Acoustic Black Hole waveguides (ABH) with Functionally Graded Perforated Rings (FGPR) which are sandwiching Sound Absorbing Layers (SAL). This class of ABH has enhanced energy dissipation characteristics derived from the simultaneous flow through the perforations and the sound absorbing layers. With such capabilities, the proposed ABH/FGPR provides rapid attenuation of the propagating waves as it travels along the length of the waveguide. The prediction of the behavior and the optimal design of the proposed ABH/FGPR are carried out using a COMSOL-based finite element modeling (FEM) approach. Numerical simulations are conducted to demonstrate the merits and behavior of various favorable configurations of the proposed ABH. The predictions of the FEM are compared to validate their accuracies. The theoretical predictions are further validated against experimental results using the ACUPRO impedance tube. Comparisons between the predictions and measurements reveal close agreements. Furthermore, the obtained results emphasize the importance of using SAL in extending the energy absorbing characteristics of the proposed ABH/FGPR over broad frequency range even with fewer number of rings.

  PublisherDOI

• Active Willis metamaterials with programmable density and stiffness

  Journal of Applied Physics · 2024-07-09 · 6 citations

  articleOpen access1st authorCorresponding

  Investigation and implementation of Active Willis Metamaterials (AWM) have been done exclusively, in all the available literature, by approaches that do not rely on any solid control theory basis. When coupled with piezoelectric control elements, the available approaches have not included, from the first principles, the exact form of the constitutive relationship of the piezoelectric materials. Furthermore, in all these approaches, stability analysis, robustness, ability to accommodate uncertainty or parameter changes, or consideration of disturbance rejection has not been addressed at all. More importantly, the available formulations have always mixed the flow and effort variables of the AWM, resulting in a form that is totally incompatible for the use in generating, investigating, or even designing any appropriate sensing or control applications of the material. In this paper, the piezoelectric-based AWM is modeled, from the first principles, to develop a constitutive coupling form that enables its use in actuation, sensing, and as an integrated controller that can be analyzed, designed, and optimized using the classical, optimal, and robust control system theories. Lagrange dynamics formulation is used to generate the equations governing the Willis coupling, the piezoelectric coupling, as well as the active robust controller. With this developed controlled-based structure of the AWM, the inherent and powerful capabilities of the AWM that lie in its ability to robustly control the material properties themselves such as the compliance (or stiffness) and specific volume (or density) are demonstrated in great detail via several numerical examples. Controlling these properties enables the AWM to be used in numerous important and imaginative applications such as cloaking, beam shifting, beam focusing, as well as many other applications that are limited only by our imagination.

  PublisherDOI

• Stability and Bandgap Characteristics of Periodic Marine Risers

  Vibration · 2024-06-26

  articleOpen accessSenior authorCorresponding

  This paper presents the concept of periodic marine risers, which is investigated in a comprehensive theoretical manner to establish tools for the design and prediction of the performance characteristics of this class of risers. The presented concept of periodic risers introduces an optimally placed and designed array of periodic inserts that reinforce the conventional riser to, on the one hand, enhance its elastic instability threshold to internal flows and, on the other hand, introduce stop/pass band characteristics that can trap the vortex shedding excitations in order to mitigate their effects. Such a concept has not been investigated in the literature. The effectiveness of the concept is investigated and demonstrated theoretically by modeling the dynamics of these risers using finite element analysis and developing their instability threshold to internal flows, as well as their bandgap characteristics by extracting the eigenvalues of the associated transfer matrices. Comparisons are established between the performance characteristics of these periodic risers and conventional risers to demonstrate the merits and limitations of the proposed concept.

  PublisherDOI

• The Biology and Laboratory Paradigm Shift: A Review of Machine Learning and Artificial Intelligence in Biomolecular Data Interpretation and Predictive Modeling

  Saudi Journal of Medicine and Public Health · 2024-12-31

  reviewOpen access

  Background: The life sciences are experiencing an explosion of data from high-throughput genomics, proteomics, and metabolomics. It is a challenging problem to interpret the complex data sets in parallel with developments in artificial intelligence (AI) and machine learning (ML). Aim: This review categorizes the groundbreaking contribution of AI/ML to biomolecular data science during the period 2015-2024, elucidating its use in multi-omics analysis, protein structure prediction, and experimental automation. Methods: We performed a systematic literature review highlighting the application of sophisticated computational models such as deep neural networks, graph neural networks, and transformer architectures in diverse biomolecular data. Results: Our results establish that AI/ML has changed the discipline at its core. These technologies facilitate the discovery of new biomarkers and drug targets from multi-omics data and have made breakthrough achievements in protein structure prediction using AlphaFold2. In addition, AI is now automating experimental design, making closed-loop systems that accelerate discovery. Conclusion: AI and ML are no longer ancillary tools but intrinsic drivers of a new paradigm in molecular biology. Although data quality and interpretability challenges persist, the incorporation of AI is imperative for decoding the patterns of complex biological systems and developing personalized medicine.

  PublisherDOI

• The Biology and Laboratory Paradigm Shift: A Review of Machine Learning and Artificial Intelligence in Biomolecular Data Interpretation and Predictive Modeling

  Saudi Journal of Medicine and Public Health · 2024-12-31

  articleOpen access

  Background: The life sciences are experiencing an explosion of data from high-throughput genomics, proteomics, and metabolomics. It is a challenging problem to interpret the complex data sets in parallel with developments in artificial intelligence (AI) and machine learning (ML). Aim: This review categorizes the groundbreaking contribution of AI/ML to biomolecular data science during the period 2015-2024, elucidating its use in multi-omics analysis, protein structure prediction, and experimental automation. Methods: We performed a systematic literature review highlighting the application of sophisticated computational models such as deep neural networks, graph neural networks, and transformer architectures in diverse biomolecular data. Results: Our results establish that AI/ML has changed the discipline at its core. These technologies facilitate the discovery of new biomarkers and drug targets from multi-omics data and have made breakthrough achievements in protein structure prediction using AlphaFold2. In addition, AI is now automating experimental design, making closed-loop systems that accelerate discovery. Conclusion: AI and ML are no longer ancillary tools but intrinsic drivers of a new paradigm in molecular biology. Although data quality and interpretability challenges persist, the incorporation of AI is imperative for decoding the patterns of complex biological systems and developing personalized medicine.

  PublisherOA PDFDOI

• Acoustic black hole with functionally graded perforated rings

  Journal of Applied Physics · 2024-06-18 · 10 citations

  articleOpen accessSenior author

  A new class of acoustic black hole (ABH) waveguides is presented, which relies in its operation on an array of optimally designed functionally graded perforated rings (FGPRs). In this manner, the developed ABH is provided with built-in energy dissipation characteristics generated by virtue of the flow through perforations, which enhances its acoustic absorption behavior and makes the speed of the propagating waves vanish faster when reaching the end of the waveguide. Furthermore, the particular design of the rings enables sandwiching of additional porous absorbing layers between the rings to further boost the absorption characteristics of the proposed ABH. Accordingly, the operating principle of the new class of ABH is radically different from that of the conventional ABH that employs sequential solid-flat rings of decreasing inner radii to create a virtual power law taper necessary for generating the black hole effect, but through reactive means rather than the effective dissipative means of the proposed ABH. Therefore, this paper develops a transfer matrix modeling (TMM) approach to model the absorption and reflection characteristics of the new class of ABH, in an attempt to predict its behavior, optimize the selection of its design parameters, and more importantly, demonstrate its merits as effective means for controlling sound propagation. Numerical examples are presented to highlight the merits and behavior of the proposed ABH. Predictions of the TMM are validated against experimental results that are available in the literature for one and two micro-perforated plates. Comparisons are also established between the ABH with FGPR and the conventional ABH in order to distinguish the behavior and underlying principles of their operations.

  PublisherDOI

• Why active Willis metamaterials? A controllability and observability perspective

  The Journal of the Acoustical Society of America · 2024-11-01 · 3 citations

  article1st authorCorresponding

  Recently, active Willis metamaterials (AWM) have been the focus of extensive investigations because of their unique electro-elastic coupling characteristics. However, the treatments of this class of materials have been carried out exclusively, in all the available literature, by approaches that do not rely on solid control theory basis. In this paper, the emphasis is placed on revealing very important control features that are inherent to this class of materials because of their Willis coupling characteristics. These features lie in the enhanced controllability and observability properties of the AWM as compared to non-Willis active materials. Such control properties enable the AWM to possess broad sensing and actuation capabilities that can lend this material to be an effective means for monitoring and controlling the behavior of numerous critical applications, such as acoustic cloaking, particularly when integrated with appropriate robust control strategies. A simple example of a piezoelectric-based AWM is presented to demonstrate its effective control capabilities and distinguish this class of materials from conventional materials. In the selected example, the AWM is structured from two dissimilar masses connected by a piezoelectric spring. Lagrange dynamics formulation is utilized to generate the equations governing the Willis coupling, the piezoelectric coupling, and reveal the inherent control features. With this developed controlled-based structure of the AWM, it is shown that the AWM can simultaneously monitor and control both the strain and velocity whereas the conventional active material, which is formed from two similar masses connected by a piezoelectric spring, can only measure and control the strain alone. It is envisioned that the revealed control metrics for the simple one-dimensional AMW example can serve as means for investigating the potential of AMW's of higher dimensionality.

  PublisherDOI

Recent grants

• Shape and Health Monitoring of Morphing Structures

  NSF · $230k · 2006–2009

Frequent coauthors

• Osama J. Aldraihem

  King Saud University

  61 shared

• S. Poh

  University of Maryland, College Park

  41 shared

• W. Akl

  Nile University

  35 shared

• Massimo Ruzzene

  University of Colorado Boulder

  34 shared

• Mostafa Nouh

  21 shared

• Jong‐Suk Ro

  Chung-Ang University

  20 shared

• Tung-Huei Chen

  National Yang Ming Chiao Tung University

  17 shared

• John J. Gilheany

  Catholic University of America

  12 shared

Education

• Ph.D, Mechanical Engineering

  University of Wisconsin Madison

  1973

Awards & honors

• Fellow, American Society of Mechanical Engineers (1996)
• Who’s Who of American Inventors (1996)
• Engineering Alumni Association Outstanding Faculty Research…
• ASME Adaptive Structures and Material Systems Award (2009)
• Pi Tau Sigma Purple Camshaft Teaching Award (2009)