scholarly journals Reconfigurable Floquet elastodynamic topological insulator based on synthetic angular momentum bias

2020 ◽  
Vol 6 (29) ◽  
pp. eaba8656
Author(s):  
Amir Darabi ◽  
Xiang Ni ◽  
Michael Leamy ◽  
Andrea Alù
Keyword(s):  
Angular Momentum ◽  
Integrated Circuits ◽  
Phononic Crystal ◽  
Operating Conditions ◽  
Modulation Scheme ◽  
Topological Order ◽  
Interfacial Wave ◽  
Wave Transport ◽  
Momentum Bias ◽  
Mechanical Logic

Originating with the discovery of the quantum Hall effect (QHE) in condensed matter physics, topological order has been receiving increased attention also for classical wave phenomena. Topological protection enables efficient and robust signal transport; mechanical topological insulators (TIs), in particular, are easy to fabricate and exhibit interfacial wave transport with minimal dissipation, even in the presence of sharp edges, defects, or disorder. Here, we report the experimental demonstration of a phononic crystal Floquet TI (FTI). Hexagonal arrays of circular piezoelectric disks bonded to a PLA substrate, shunted through negative electrical capacitance, and manipulated by external integrated circuits, provide the required spatiotemporal modulation scheme to break time-reversal symmetry and impart a synthetic angular momentum bias that can induce strong topological protection on the lattice edges. Our proposed reconfigurable FTI may find applications for robust acoustic emitters and mechanical logic circuits, with distinct advantages over electronic equivalents in harsh operating conditions.

Analysing integration issues of the microgrid system with utility grid network

2021 ◽  
Vol 22 (1) ◽  
pp. 113-127
Author(s):  
Mulualem Tesfaye ◽  
Baseem Khan ◽  
Om Prakash Mahela ◽  
Hassan Haes Alhelou ◽  
Neeraj Gupta ◽  
...  
Keyword(s):  
Renewable Energy ◽  
Distribution System ◽  
Reactive Power ◽  
Renewable Energy Sources ◽  
Operating Conditions ◽  
Control Mode ◽  
Voltage Source ◽  
Modulation Scheme ◽  
Main Challenge ◽  
Utility Grid

Abstract Generation of renewable energy sources and their interfacing to the main system has turn out to be most fascinating challenge. Renewable energy generation requires stable and reliable incorporation of energy to the low or medium voltage networks. This paper presents the microgrid modeling as an alternative and feasible power supply for Institute of Technology, Hawassa University, Ethiopia. This microgrid consists of a 60 kW photo voltaic (PV) and a 20 kW wind turbine (WT) system; that is linked to the electrical distribution system of the campus by a 3-phase pulse width modulation scheme based voltage source inverters (VSI) and supplying power to the university buildings. The main challenge in this work is related to the interconnection of microgrid with utility grid, using 3-phase VSI controller. The PV and WT of the microgrid are controlled in active and reactive power (PQ) control mode during grid connected operation and in voltage/frequency (V/F) control mode, when the microgrid is switched to the stand-alone operation. To demonstrate the feasibility of proposed microgrid model, MATLAB/Simulink software has been employed. The performance of fully functioning microgrid is analyzed and simulated for a number of operating conditions. Simulation results supported the usefulness of developed microgrid in both mode of operation.

scholarly journals New Thick-Film Microwave Elements for Microwave Integrated Circuits

1983 ◽  
Vol 11 (1) ◽  
pp. 1-20 ◽  
Author(s):  
Janusz J. Gondek ◽  
Marek A. Wójcicki ◽  
Jan Cąber
Keyword(s):  
Thin Film ◽  
Integrated Circuits ◽  
Mathematical Models ◽  
Thick Film ◽  
Technological Process ◽  
Operating Conditions ◽  
Microwave Integrated Circuits ◽  
Thin Film Technology ◽  
Strip Lines ◽  
Constituent Elements

The realisation of microwave integrated circuits consisting of numerous elements and components, both passive and active, takes place in steps. Initially, experimental constituent elements are designed and constructed, and only after it is found that they satisfy the operating conditions, can they be integrated into a sub-system. As a result of this we obtain complicated Microwave Integrated Circuits (MICs). Initially however one has to construct basic MIC elements such as: resonators, filters, couplings, Y branch joints, circulators, etc. During research over several years carried out at the Microelectronics Department, Institute of Electronics, of the Mining and Metallurgical University of Kraków and devoted to the application of thick-film technology to MIC, the authors have devised and constructed several microwave elements using strip-lines and this paper reports of the results of their studies.Pastes produced by DU PONT/USA were used. New mathematical models for designing thick-film microwave elements have been elaborated using computer techniques. These programmes have differed from analogous ones for MIC realized by thin-film technology can be adapted, after certain modifications, to the realisation of MIC. The authors have introduced new technological operations, not used so far, to the technological process. This has made possible the production of thick-film microwave elements with parameters comparable to those obtained in thin-film technology.

Demonstration of Orbital Angular Momentum State Conversion using Two Hybrid 3D Photonic Integrated Circuits

2014 ◽  
Author(s):  
Chuan Qin ◽  
Binbin Guan ◽  
Ryan Scott ◽  
Roberto Proietti ◽  
Nicolas K. Fontaine ◽  
...  
Keyword(s):  
Angular Momentum ◽  
Integrated Circuits ◽  
Orbital Angular Momentum ◽  
Photonic Integrated Circuits ◽  
Momentum State ◽  
Angular Momentum State ◽  
Two Hybrid

Polarization Diversified Integrated Circuits for Orbital Angular Momentum Multiplexing

2015 ◽  
Vol 27 (10) ◽  
pp. 1056-1059 ◽  
Author(s):  
Binbin Guan ◽  
Chuan Qin ◽  
Ryan P. Scott ◽  
Nicolas K. Fontaine ◽  
Tiehui Su ◽  
...  
Keyword(s):  
Angular Momentum ◽  
Integrated Circuits ◽  
Orbital Angular Momentum

scholarly journals A Unified Controller for Multi-State Operation of the Bi-Directional Buck–Boost DC-DC Converter

Energies ◽  
2021 ◽  
Vol 14 (23) ◽  
pp. 7921
Author(s):  
Gabriel R. Broday ◽  
Gilney Damm ◽  
William Pasillas-Lépine ◽  
Luiz A. C. Lopes
Keyword(s):  
Feedback Linearization ◽  
Power Flow ◽  
Negative Impact ◽  
Input Voltage ◽  
Operating Conditions ◽  
Modulation Scheme ◽  
Control Loops ◽  
Variable Control ◽  
Wide Range ◽  
The Right

DC grid interfaces for supercapacitors (SCs) are expected to operate with a wide range of input voltages with fast dynamics. The class-C DC-DC converter is commonly used in this application because of its simplicity. However, it does not work if the output voltage (V2) becomes smaller than the input voltage (V1). The non-isolated bi-directional Buck–Boost DC-DC converter does not have this limitation. Its two half-bridges provide a means for controlling the power flow operating in the conventional dual-state mode, as well as multi-state, tri, and quad modes. These can be used for mitigating issues such as the Right Half Plane (RHP) zero that has a negative impact on the dynamic response of the system. Multi-state operation typically requires multi-variable control, which is not easy to realize with conventional PI-type controllers. This paper proposes a unified controller for multi-state operation. It employs a carrier-based modulation scheme with three modulation signals that allows the converter to operate in all four possible states and eight different modes of operation. A mathematical model is developed for devising a multi-variable control scheme using feedback linearization. This allows the design of control loops with simple PI controllers that can be used for all multi-state modes under a wide range of operating conditions with the same performance. The proposed scheme is verified by means of simulations.

Multifunctional One-dimensional Phononic Crystal Structures Exploiting Interfacial Acoustic Waves

2009 ◽  
Vol 1188 ◽  
Author(s):  
Albert C To ◽  
Bong Jae Lee
Keyword(s):  
Acoustic Waves ◽  
Filter Design ◽  
Phononic Crystal ◽  
Stop Band ◽  
Phononic Crystals ◽  
Thermal Barrier ◽  
Interfacial Wave ◽  
Lateral Direction ◽  
One Dimensional ◽  
Wave Filter

AbstractThe present study demonstrates that interfacial acoustic waves can be excited at the interface between two phononic crystals. The interfacial wave existing between two phononic crystals is the counterpart of the surface electromagnetic wave existing between two photonic crystals. While past works on phononic crystals exploit the unique bandgap phenomenon in periodic structures, the present work employs the Bloch wave in the stop band to excite interfacial waves that propagate along the interface and decay away from the interface. As a result, the proposed structure can be used as a wave filter as well as a thermal barrier. In wave filter design, for instance, the incident mechanical wave energy can be guided by the interfacial wave to the lateral direction; thus, its propagation into the depth is inhibited. Similarly, in thermal barrier design, incident phonons can be coupled with the interfacial acoustic wave, and the heat will be localized and eventually dissipated at the interface between two phononic crystals. Consequently, the thermal conductivity in the direction normal to the layers can be greatly reduced. The advantage of using two phononic crystals is that the interfacial wave can be excited even at normal incidence, which is critical in many engineering applications. Since the proposed concept is based on a one-dimensional periodic structure, the analysis, design, and fabrication are relatively simple compared to other higher dimensional material designs.

Topologically robust sound wave transport in two-dimensional phononic crystal with a circular rod arrangement in water

2020 ◽  
Vol 59 (SK) ◽  
pp. SKKA05
Author(s):  
Kenshi Okuno ◽  
Kenji Tsuruta
Keyword(s):  
Sound Wave ◽  
Phononic Crystal ◽  
Two Dimensional ◽  
Wave Transport

Reliability of GaN on Si FETs and MMICs

2009 ◽  
Vol 1195 ◽  
Author(s):  
Donald A. Gajewski ◽  
Walter Nagy ◽  
Allen W. Hanson ◽  
J.W. Johnson ◽  
K J Linthicum
Keyword(s):  
Integrated Circuits ◽  
Field Effect Transistors ◽  
Temperature Cycling ◽  
Operating Conditions ◽  
Accelerated Life Test ◽  
Operating Life ◽  
Worst Case ◽  
Technology Platforms ◽  
Volume Production ◽  
Gan On Si

AbstractThis paper reviews the reliability results for the gallium nitride on silicon (GaN-on-Si) technologies for commercial and military communications markets. Two technology platforms have been qualified for volume production: one consisting of discrete heterostructure field effect transistors (HFETs) and the other consisting of HFETs integrated with passive components to form monolithic microwave integrated circuits (MMICs). The technology platform qualifications for volume production have been achieved through intrinsic reliability tests on the active and passive device elements as well as extrinsic reliability tests at the product level. This paper presents reliability results on accelerated life test (ALT), high temperature operating life under DC and RF stress (DC/RF-HTOL), electrostatic discharge (ESD), ramped voltage breakdown, electromigration, temperature cycling, robustness under voltage standing wave ratio (VSWR) mismatch conditions, and diode stability. Degradation and breakdown mechanisms are discussed in relation to material properties reliability. The results show that the HFET and MMIC technology platforms display reliable performance for 20 year product lifetime at worst case operating conditions.

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