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Antenna Placement and Performance Tradeoffs with Hand Blockage in Millimeter Wave Systems
摘要： The ongoing commercial deployment of millimeter wave systems brings into focus a number of practical issues in form factor user equipment (UE) design. With wavelengths becoming smaller, antenna gain patterns becoming directional, and link budgets critically dependent on beamforming, it becomes imperative to use a number of antenna modules at different locations of the UE for good performance. While more antennas/modules can enhance beamforming array gains, it comes with the tradeoff of higher component cost, power consumption of the associated radio frequency circuitry, and a beam management overhead in learning the appropriate beam weights. Thus, the goal of a good UE design is to provide robust spherical coverage corresponding to good array gains over the entire sphere around the UE with a low beam management overhead, complexity, and cost. The scope of this paper is to study the implications of two popular commercial millimeter wave UE designs (a face and an edge design) on spherical coverage. We show that analog beam codebooks can result in good performance for both the designs, and the edge design provides a better tradeoff in terms of robust performance (with hand blockage), beam management overhead, implementation complexity from an antenna placement standpoint and cost.
关键词： hand blockage,5G-New Radio,Millimeter wave,spherical coverage,commercial deployments,antenna placement,UE design,modular design
更新于2025-09-23 15:23:52
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[IEEE 2018 IEEE Energy Conversion Congress and Exposition (ECCE) - Portland, OR, USA (2018.9.23-2018.9.27)] 2018 IEEE Energy Conversion Congress and Exposition (ECCE) - High-Efficiency Weight-Optimized Fault-Tolerant Modular Multi-Cell Three-Phase GaN Inverter for Next Generation Aerospace Applications
摘要： The aircraft industry demands a significant increase in terms of efficiency and gravimetric power density of power converters for next generation aerospace applications. Between the two minimum targets, i.e. an efficiency > 98 % and a gravimetric power density > 10 kW/kg, the specification concerning the converter weight is the most challenging to fulfill. Since cooling systems and magnetic components dominate the weight breakdown of conventional converter concepts, multi-cell topologies, enabling improved semiconductors performance and reduced filtering requirements, are foreseen as promising solutions for the power electronics on board of More Electric Aircraft. On the other hand, the necessary simultaneous operation of a high number of cells inevitably limits the reliability of multi-cell converters if redundancy is not provided. In this paper, a favorable scaling trend of power density with respect to reliability, aiming to guarantee fault-tolerant operation without affecting the performance figures, is identified in modular multi-cell converters. Thus, a 45 kW weight-optimized modular multi-cell three-phase inverter featuring a redundant power stage is optimized, achieving an efficiency of 99 % and a gravimetric power density of 22.8 kW/kg.
关键词： Multi-Objective Optimization,Figure of Merit of Power Semiconductors,Power Converters Reliability,Modular Multi-Cell Inverter,More Electric Aircraft
更新于2025-09-23 15:23:52
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Development of the readout system for a time projection chamber prototype
摘要： A new GEM-TPC prototype with a laser calibration system is being designed to study the key issues of high-precision track detection whose aimed spatial resolution is better than 100 μm. Meanwhile, a readout system with scalability for the TPC is also being developed. Design of the readout system is based on the architecture of front-end ASICs and commercial ADCs for its advantages at high count rates. Given the requirement of several hundred channels, the system is composed of multiple front-end cards and DAQ boards. The DAQ boards are daisy-chained via bidirectional optical fibers, which transmit clock, trigger, data and control signals simultaneously. To achieve timing synchronization, the GigaBit Transceiver (GBT) firmware is employed to ensure fixed latency between the boards. This paper is focused on the design and setup of the DAQ system, including clock structure, trigger alignment, high-speed data acquisition, etc. The DAQ system consisting of 512 channels has been built, and tests have proved that the entire system works correctly and meets the expected requirements.
关键词： Trigger concepts and systems (hardware and software),Electronic detector readout concepts (gas, liquid),Modular electronics,Data acquisition concepts
更新于2025-09-23 15:22:29
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Photoinduced electron transfer kinetics of linked Ru-Co photocatalyst dyads
摘要： Two new supramolecular photocatalyst dyads based on the [Ru(2,2′-bipyridine)3]2+ photosensitizer linked to a macrocyclic Co(II)tetra(pyridyl) catalyst for proton reduction are reported. The dyads differ primarily in the bridging ligand which links the molecular modules; the first being a short and flexible linker, and the second a longer and electronically conjugated linker. Ultrafast transient optical spectroscopy was used to monitor the photoinduced kinetics of the dyads following visible excitation of the photosensitizer module. Direct comparison of transient spectra and kinetics indicates that there are indeed substantial differences between the ultrafast transient optical spectroscopy of the dyads, but there is no indication of oxidative quenching of the photosensitizer module by the catalyst module. These initial design and characterization studies of the linked Ru(II)—Co(II) dyads provide an important foundation for advanced designs of systems for efficient solar energy conversion by molecular architectures.
关键词： Ruthenium,Cobalt,Photoinduced electron transfer,Modular assembly,Photocatalyst dyads
更新于2025-09-23 15:22:29
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A Hybrid MMC-Based Photovoltaic and Battery Energy Storage System
摘要： This paper proposes a new configuration and its control strategy for a modular multilevel converter (MMC)-based photovoltaic (PV)-battery energy storage (BES) system. In the MMC-based PV-BES system, each PV submodule is interfaced from its dc side with multiple PV generators using isolated dual active bridge (DAB) dc-dc converters. One BES system is embedded into each arm of the converter and is connected to the dc port of the associated BES submodule using multiple isolated DAB converters. The embedded BES systems are used to smooth the output power of the PV generators and limit the rate of change of the power delivered to the host grid. Moreover, they enable compensation of power mismatches between the arms and legs of the system by exchanging power with the arms of the converter. The paper then proposes a hybrid power mismatch elimination strategy using a combination of power exchange with the arms of the converter and internal power flow control of the MMC. The proposed hybrid power mismatch elimination strategy employs BES systems and differential currents to compensate power mismatches and transfer power between the arms and legs of the converter, respectively. The effectiveness of the proposed power smoothing technique using the embedded BES systems and hybrid power mismatch elimination strategy is demonstrated using time-domain simulations conducted on a switched model of the PV-BES system in PSCAD/EMTDC software environment.
关键词： control,modular multilevel converter,power electronics,battery energy storage,photovoltaic,power mismatch,Differential current,energy conversion,integration
更新于2025-09-23 15:22:29
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Modular-value-based metrology with spin coherent pointers
摘要： We discuss an optimal modular-value-based measurement with a spin coherent pointer: A quantum system is exposed to a field whose strength is to be estimated through its modular value. We evaluate the quantum Fisher information as a figure of merit. We found that the modular-value-based measurement can reach the same ultimate precision limit of the estimation as those of measurements without postselections. The quantum Fisher information can be increased when the dimension of the pointer state increases. We also consider the pointer under a phase-flip error. Our study should motivate researchers to apply the modular-value-based measurements for quantum metrology.
关键词： Quantum Fisher information,Modular values,Weak values,Quantum metrology
更新于2025-09-23 15:21:21
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A novel photovoltaic battery energy storage system based on modular multilevel converter
摘要： Modular multilevel converters (MMCs) have been widely applied in photovoltaic battery energy storage systems (PV-BESSs). In this paper, a novel topology of PV-BESS based on MMC is proposed, where the batteries are connected to the sub-modules through DC-DC converters. It is necessary to analyze the control strategies of both DC-DC converters and MMC. Specifically, the capacitor voltage balancing and the modulation mode are important. The sorting method is proposed to balance the capacitor voltages in this paper. Moreover, carrier phase shift-square wave modulation with the highest voltage utilization ratio and the highest power transfer capability is proposed to generate PWM singles for MMC-PV-BESS. In order to verify the availability of the proposed control strategy, a simulation model is built and related experiments are carried out. The simulation results and experimental results are consistent with the theory. As a result, the voltages of all capacitors could be balanced, and the MMC-PV-BESS could reliably work.
关键词： photovoltaic,modular multilevel converter,battery energy storage system,DC-DC converter,control strategy
更新于2025-09-23 15:21:21
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[IEEE 2019 International Conference on Microwave and Millimeter Wave Technology (ICMMT) - Guangzhou, China (2019.5.19-2019.5.22)] 2019 International Conference on Microwave and Millimeter Wave Technology (ICMMT) - Design of Tightly Coupled Planar Ultrawideband Modular Antenna with Improved Low-frequency Gain Based on AMC Structure
摘要： A novel tightly coupled planar ultrawideband (UWB) modular antenna (PUMA) with improved low-frequency gain based on artificial magnetic conductor (AMC) is presented in this paper. Conventional PUMA becomes popular for ease of fabrication and low profile. However, it also suffers from low low-frequency gain. A dual-band (6-10.5 GHz, 12-18 GHz) AMC structure is introduced to help improve low-frequency gain. The proposed antenna possesses 3:1 bandwidth (VSWR<3). The low-frequency gain (6-10.5 GHz) of 1*16 and 4*4 array is improved by 8 dBi and 5 dBi respectively. The high-frequency gain (12-18 GHz) is improved by 2 dBi and 4 dBi. Detailed simulation is also presented.
关键词： modular antenna,low-frequency gain,AMC structure,Ultrawideband
更新于2025-09-23 15:21:01
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[IEEE 2018 XIII International Conference on Electrical Machines (ICEM) - Alexandroupoli, Greece (2018.9.3-2018.9.6)] 2018 XIII International Conference on Electrical Machines (ICEM) - Design of a GaN Based Integrated Modular Motor Drive
摘要： In this study, design procedure of an Integrated Modular Motor Drive (IMMD) is presented focusing on high power density. The design is based on a permanent magnet synchronous motor (PMSM) and GaN FETs. Fractional slot concentrated windings are used on the stator. Slot/pole combination and winding configuration is selected based on having low cogging torque and high winding factor. An extended motor drive inverter topology is proposed where 2-level voltage source inverters are connected both in series and parallel. Optimum selection of number of modules is discussed and power semiconductor devices are selected based on loss characterization. Optimum DC link capacitor bank is determined and the effect of interleaving is investigated. The performance of the motor is validated with ANSYS/Maxwell simulations. Motor drive performance is obtained with MATLAB/Simulink simulations. The efficiency of the motor drive is enhanced by 2% compared to a conventional motor drive. An overall system power density over 1 kW/lt has been achieved with the proposed series/parallel motor drive configuration having GaN FETs.
关键词： Permanent magnet synchronous motor,Modular motor,Power density,Gallium nitride,Integrated motor drive
更新于2025-09-23 15:21:01
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Polarization-Controlled Dual-Programmable Metasurfaces
摘要： Programmable metasurfaces allow dynamic and real-time control of electromagnetic (EM) waves in subwavelength resolution, holding extraordinary potentials to establish meta-systems. Achieving independent and real-time controls of orthogonally-polarized EM waves via the programmable metasurface is attractive for many applications, but remains considerably challenging. Here, a polarization-controlled dual-programmable metasurface (PDPM) with modular control circuits is proposed, which enables a dibit encoding capability in modifying the phase profiles of x- and y-polarized waves individually. The constructed extended interface circuit is able to extend the number of control interfaces from a field programmable gate array by orders of magnitude and also possesses memory function, which enhance hugely the rewritability, scalability, reliability, and stability of PDPM. As a proof-of-concept, a wave-based exclusive-OR logic gate platform for spin control of circularly-polarized waves, a fixed-frequency wide-angle dual-beam scanning system, and a dual-polarized shared-aperture antenna are demonstrated using a single PDPM. The proposed PDPM opens up avenues for realizing more advanced and integrated multifunctional devices and systems that have two independent polarization-controlled signal channels, which may find many applications in future-oriented intelligent communication, imaging, and computing technologies.
关键词： orthogonally-polarized electromagnetic waves,beam controls,digital logic platforms,modular control circuits,dual-programmable metasurfaces
更新于2025-09-23 15:19:57