المؤلفون: Wunsch, Carl¹ (AUTHOR) carl.wunsch@gmail.com

المصدر: IEEE Technology & Society Magazine. Jun2024, Vol. 43 Issue 2, p33-35. 3p.

مصطلحات موضوعية: GRAVITATIONAL waves, SHOCK waves, ELECTROMAGNETISM, WORLD War II, COLLECTIVE behavior, ROSSBY waves

مصطلحات جغرافية: DURHAM (N.C.)

Reviews & Products: OXFORD English Dictionary

People: WOOLF, Virginia, 1882-1941

مستخلص: The Oxford English Dictionary lists eight distinct meanings for the noun “wave” and 10 for the verb form. Physical phenomena of waves, as known by scientists and engineers, are ubiquitous and include those on water surfaces, in sound, seismology, clouds, electromagnetism, cosmic gravitational radiation, in sand, and so on. In the conventional technical sense, waves almost always have some mathematically stated connection between the wavelength (distance between crests), the phase speed (or frequency), and, sometimes, the amplitude. Various exceptions are known, including solitary waves (solitons) and shock waves. Often the waves are mere propagators of motion, but in other cases, they can transport material as well. With the evolution of the English language, the term “wave” has been invoked to describe a huge variety of phenomena ranging from waves of disease, disorder, and emotion, to hair (“permanent waves”), to crowd behavior in stadiums, to “waving” goodbye, to the World War II women's military WAVES, to the titles of novels—for example, from Virginia Woolf. [ABSTRACT FROM AUTHOR]

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المؤلفون: Mansoorzare, Hakhamanesh¹ hakha@knights.ucf.edu, Abdolvand, Reza¹

المصدر: IEEE Transactions on Microwave Theory & Techniques. Nov2022, Vol. 70 Issue 11, p5195-5204. 10p.

مصطلحات موضوعية: ACOUSTIC surface waves, LAMB waves, SIGNAL processing, LITHIUM niobate, ACOUSTIC phonons, WAVEGUIDES, RADIO interference, PIEZOELECTRIC thin films

مستخلص: This work explores micromachined heterostructured waveguides that leverage strong interactions between acoustic phonons and electrons to enable radio frequency (RF) signal amplification or attenuation. A thin-film piezoelectric-on-semiconductor stack is tailored to generate high electromechanical coupling Lamb waves that are impacted by high mobility electrons within a microacoustic waveguide. Lamb waves are generated by RF signal via interdigital electrodes on the piezoelectric layer; by applying a voltage to the semiconductor layer so that the electrons lead mechanical waves, the RF signal is amplified through the acoustoelectric (AE) effect. Conversely, the signals propagating faster or in the opposite direction of the electron flow undergo attenuation, rendering the waveguide nonreciprocal. Research on the AE effect dates to the mid-20th century and until now has been mostly focused on surface acoustic waves (SAWs). In this work, enabled by high-quality bonded thin films of lithium niobate (LN) and silicon (Si), it is shown that fundamental symmetric ($S0$) Lamb mode waveguides at 100 s of MHz can achieve more than 40 dB of AE gain and strong nonreciprocal transmission with less than 10 mW of bias power consumption. This could enable implementation of switches, delay lines, isolators, and circulators, which are critical for interference cancellation and full-duplex radio. The AE effect is observed to be stronger in some higher $S0$ harmonics, allowing for scaling to higher frequencies with optimized electrodes that have more relaxed critical dimensions. In addition, up to 5.5-dB sustained terminal gain measured in this work implies the potential for transistor-less amplifiers that could be implemented in concert with more traditional acoustic devices in a single-chip manner. [ABSTRACT FROM AUTHOR]

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المؤلفون: Jin, Xin¹ dutjinxin@mail.dlut.edu.cn, Chen, Xiyou¹ chenxy@dlut.edu.cn, Qi, Chen¹ qichen@dlut.edu.cn, Li, Tao¹ taott@mail.dlut.edu.cn

المصدر: IEEE Transactions on Industrial Electronics. Mar2023, Vol. 70 Issue 3, p2497-2507. 11p.

مصطلحات موضوعية: ELECTROMAGNETIC waves, OCEAN wave power, ELECTROMAGNETIC fields, ELECTROMAGNETIC theory, MAXWELL equations

الشركة/الكيان: TESLA Inc. TSLA

مستخلص: Single-wire power transmission (SWPT) is a power transmission method that uses only one wire to realize long-distance transmission of power. For deep insight, the theory of electromagnetic surface waves in this article is applied to reveal the principle of a long-distance large-scale SWPT system. Maxwell's equations under two different media in this system are established, based on them and the boundary conditions on the interface of the media, the propagation law of electromagnetic field energy in the SWPT system is analyzed. A simulation model is built by high frequency simulator structure (HFSS). The distribution law of the Poynting vector in different situations is studied to verify the correctness of the theoretical analysis. Moreover, long-distance transmission experiments are carried in the campus. It is shown that the transmission power can reach 300 W or 135 W when the transmission distance is 100 m or 200 m, respectively. [ABSTRACT FROM AUTHOR]

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المؤلفون: Arzhannikov, Andrey V.¹, Sinitsky, Stanislav L.¹, Popov, Sergei S.¹, Timofeev, Igor V.¹, Samtsov, Denis A.², Sandalov, Evgeny S.¹ e.s.sandalov@inp.nsk.su, Kalinin, Petr V.¹, Kuklin, Konstantin N.¹, Makarov, Maksim A.¹, Rovenskikh, Andrey F.¹, Stepanov, Vasilii D.¹, Annenkov, Vladimir V.¹, Glinsky, Vladimir V.¹

المصدر: IEEE Transactions on Plasma Science. Aug2022, Vol. 50 Issue 8, p2348-2363. 16p.

مصطلحات موضوعية: SUBMILLIMETER waves, ELECTRON beams, PLASMA density, RELATIVISTIC electron beams, ELECTRON plasma, PLASMA waves

مستخلص: This article presents the results of experimental studies on radiation flux generation in the submillimeter wavelength range due to a strong beam–plasma interaction. A relativistic electron beam (REB) with parameters 0.5 MeV/12 kA/ $6 \mu \text{s}$ pumps plasma waves in a plasma column with a length of ~2 m at a plasma density of $\sim 10^{15} {\mathrm{ cm}}^{-3}$ in a magnetic field of ~4 T. In the presence of density gradients in the plasma column, direct measurements of the energy content of the radiation flux 18 cm in diameter leaving the plasma column into the atmosphere showed that its value reaches 5–7 J. The pulse duration of the flux at half of its amplitude was about $0.5 \mu \text{s}$ , and therefore, the pulse power was at the level of ~10 MW. In this series of experiments, the spectral composition of the radiation flux in the frequency range of 0.1–0.5 THz and the energy distribution function of the beam electrons passed through the plasma have been measured. [ABSTRACT FROM AUTHOR]

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المؤلفون: Lan, Feng¹, Li, Mengzhen¹, Guo, Zugen¹, Zhang, Ruifeng¹, Luo, Jiezhong¹, Lai, Han¹, Duan, Zhaoyun¹, Gong, Yubin¹, Xiao, Fei¹, Travish, Gil², Gong, Huarong¹ hrgong@uestc.edu.cn

المصدر: IEEE Transactions on Electron Devices. Aug2022, Vol. 69 Issue 8, p4586-4591. 6p.

مصطلحات موضوعية: TRAVELING-wave tubes, SUBMILLIMETER waves, SLOW wave structures, FREE electron lasers, PHASE shifters, ELECTRON beams, ELECTROMAGNETIC waves

مستخلص: The folded-waveguide (FWG) traveling-wave tube (TWT) is a promising high-power terahertz (THz) amplifier. However, it is challenging to develop THz FWG-TWT with high beam–wave interaction efficiency. In this work, a phase jumping technology, which originates from free-electron lasers, is proposed to boost the beam–wave interaction efficiency of THz FWG-TWT. A modified slow wave structure acts as the phase shifter to adjust the phase gap between electron beam and electromagnetic wave. By jumping the phase gap to an appropriate value, the bunching center of electron beam keeps for a long time in the deceleration region. Thus, more energy is transferred to electromagnetic wave from bunching electron beam. To verify such proposition, a THz FWG-TWT example utilizing the phase jumping is presented in this article. Compared with conventional one, its efficiency within the operation bandwidth from 212 to 224 GHz is improved by 60%–140%. [ABSTRACT FROM AUTHOR]

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المؤلفون: Sun, Jiajiang¹ (AUTHOR) sunjiajiang@hust.edu.cn, Zhao, Jin¹ (AUTHOR) jinzhao617@163.com, Tian, Lisi² (AUTHOR) tianlisi@cumt.edu.cn, Song, Yujin¹ (AUTHOR) songyujin@hust.edu.cn, Liu, Yang¹ (AUTHOR) yangliu30@gmail.com

المصدر: IEEE Transactions on Power Electronics. Dec2022, Vol. 37 Issue 12, p14126-14140. 15p.

مصطلحات موضوعية: *BANDWIDTHS, AMPLITUDE modulation, SQUARE waves, NOISE, PERMANENT magnet motors, PULSE width modulation

مستخلص: The high-frequency (HF) signal injection method has been widely used in sensorless control for IPMSM drives. However, the audible noise caused by HF injection restricts the sensorless application. Moreover, the control bandwidth of systems based on sinusoidal multifrequency injection or variable-frequency injection for audible noise reduction is limited due to the need for filters. This article proposes a novel amplitude modulation multirandom frequency injection (AMMRI) method to improve control bandwidth and reduce audible noise. First, the detailed message signal modulation, error extraction, position tracking, and position estimation error compensation based on amplitude-modulated voltage signal are derived and analyzed. Because the filters for HF current and error extractions are removed, the control bandwidth is improved. Second, in order to reduce audible noise, the proposed AMMRI is derived by selecting the message signal according to equal-loudness contour. The proposed method improves the control bandwidth compared to conventional multifrequency injection and reduces audible noise compared to conventional square wave injection. Finally, experimental results verify the proposed method on a 1.5-kW IPMSM platform. [ABSTRACT FROM AUTHOR]

: Copyright of IEEE Transactions on Power Electronics is the property of IEEE and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

المؤلفون: Yu, Kailiang¹ (AUTHOR) 230198654@seu.edu.cn, Wang, Zheng¹ (AUTHOR) zwang@eee.hku.hk

المصدر: IEEE Transactions on Power Electronics. Nov2022, Vol. 37 Issue 11, p12973-12979. 7p.

مصطلحات موضوعية: *COST control, PERMANENT magnet motors, SQUARE waves, VOLTAGE

مستخلص: Position sensorless control of interior permanent magnet synchronous motors (IPMSMs) is of great importance for the sake of the cost reduction and robustness improvement. An improved position sensorless method based on adjustable high-frequency (HF) square-wave voltage injection has been proposed for the IPMSM drive under zero- and low-speed regions. The general detection method of position from positive- and negative-sequence HF current response has been developed by the simple algebraic operations of data at some adjacent sampling instants. In addition, the proposed method not only can retain the advantage of the removal of low-pass filters in current feedback but also can increase the voltage margin of inverter with adjustable frequency setting of HF signal compared with existing square-wave voltage injection methods. Comprehensive experimental results have been given to verify the proposed theoretical analysis. [ABSTRACT FROM AUTHOR]

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المؤلفون: Xiao, Hongfei¹ (AUTHOR) d202080611@hust.edu.cn, Peng, Han¹ (AUTHOR) misspenghan@163.com, Liu, Xianchao¹ (AUTHOR) m202071547@hust.edu.cn, Sun, Hanyi¹ (AUTHOR) sunhy@hust.edu.cn

المصدر: IEEE Transactions on Power Electronics. Nov2022, Vol. 37 Issue 11, p13192-13204. 13p.

مصطلحات موضوعية: *POWER resources, ELECTROMAGNETIC waves, ENERGY harvesting, MAGNETIC hysteresis, HYSTERESIS, ELECTRIC current rectifiers, HARMONIC distortion (Physics), HARMONIC analysis (Mathematics)

مستخلص: Utilizing coil inductor of electromagnetic vibration energy harvester (EVEH) to form single stage ac–dc boost converter can make the self-powered milli-power system more compact. However, large output current harmonics of EVEH significantly degraded the output power in such system. This article proposes a new approach of adopting hysteresis current control to realize maximum power point tracking (MPPT) and reduce current harmonics in inductor-less converter by using auxiliary coils. The output characteristics and correlations between multiple coils are firstly studied to verify the feasibility of using auxiliary coil to represent the output of main coil. The optimal winding strategy for main coil and auxiliary coils is revealed for no degradation on maximum output power of main coil. Based upon these, a completely self-powered multicoil EVEH system is designed with auxiliary coils as reference for MPPT controller and as auxiliary power supply in cold-start. Experiments show that the designed prototype can obtain 9.54 mW output power at acceleration of 3 m/s2, with the overall efficiency of 77.6%. To charge a 10 mF supercapacitor from zero to 5 V, an average output power of 7.27 mW can be obtained with an average charging efficiency of 62.4%. In addition, the start-up method adopting auxiliary coil allows the system to cold-start when the output voltage is lower as 0.5 V. The proposed approach has been demonstrated to achieve high overall efficiency in milli-power self-powered EVEH system and also has significant advantages in cost and volume compared with using external devices to obtain reference. [ABSTRACT FROM AUTHOR]

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المؤلفون: Katwe, Mayur¹ mayurkatwe@gmail.com, Singh, Keshav¹ keshav.singh@mail.nsysu.edu.tw, Clerckx, Bruno² b.clerckx@imperial.ac.uk, Li, Chih-Peng¹ cpli@faculty.nsysu.edu.tw

المصدر: IEEE Transactions on Communications. Nov2022, Vol. 70 Issue 11, p7365-7383. 19p.

مصطلحات موضوعية: MILLIMETER waves, FRACTIONAL programming, RIEMANNIAN manifolds, K-means clustering, DEGREES of freedom, BEAMFORMING

مستخلص: In this paper, a reconfigurable intelligent surfaces (RISs)-aided millimeter wave (mmWave) uplink (UL) rate-splitting multiple access (RSMA) system is investigated which targets to achieve better rate performance and enhanced coverage capability for multiple users. The considered UL RSMA model splits the rate for each user by dividing their message into multiple parts and hence exploits all the necessary degrees of freedom to achieve maximum capacity region and high user fairness. In particular, we focus on the sum-rate maximization for considered UL RSMA system subject to joint optimization of power allocation to the UL users and beamforming design, i.e., active receive beamforming at the base-station (BS) and passive beamforming at multiple RISs. To efficiently mitigate high inter-node interference in multi-user scenario, we first provided a low-complex user pairing scheme based on k-means clustering and then develop an effective low-cost alternating optimization framework to solve the joint optimization problem sub-optimally by decoupling the problem into different sub-problems of power allocation and beamforming design. Specifically, the sub-problems of power allocation and beamforming design are solved using successive convex approximation, Riemannian manifold and fractional programming techniques. Later, the unified solution based on block coordinate descent (BCD) algorithm is proposed. Extensive numerical simulations validate that the user-clustering effectively significantly improves the performance gain and the considered RSMA system outperforms the conventional multiple schemes in terms rate and user-fairness. Also, the exploitation of spatial correlation among each RIS elements i.e., non-diagonal phase-matrices at each RIS achieve better performance that conventional diagonal phase-matrices setting. [ABSTRACT FROM AUTHOR]

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المؤلفون: Xu, Jinpeng¹ xujinpeng@buaa.edu.cn, Cheng, Xiang² xiangcheng@pku.edu.cn, Bai, Lin¹ l.bai@buaa.edu.cn

المصدر: IEEE Transactions on Antennas & Propagation. Nov2022, Vol. 70 Issue 11, p10936-10950. 15p.

مصطلحات موضوعية: *STATISTICAL correlation, *STOCHASTIC models, MILLIMETER waves, ANTENNA arrays, TRANSFER functions, RADAR in aeronautics

مستخلص: In this article, a 3-D geometry-based stochastic model (GBSM) is proposed for millimeter wave (mmWave) massive multiple-input multiple-output (MIMO) unmanned aerial vehicle (UAV) channels. The proposed model is the first mmWave massive MIMO UAV two-cylinder GBSM that enables to jointly model the channel space-time-frequency non-stationarity by a novel variable parameter-based method. In this novel method, key parameters of UAV channels are assumed to vary in space, time, and frequency domains, and the effect of the unique UAV-related parameters is further taken into account, such as the UAV’s altitude, velocity, and moving directions. Based on the proposed model, some statistical properties are derived, including the time-variant transfer function (TVTF), space-time-frequency correlation function (STF-CF), Doppler power spectral density (PSD), and the standard deviation of Doppler frequency on antenna arrays. Simulation results show that the channel non-stationarity in space, time, and frequency domains can be captured, and the aforementioned UAV channel-related parameters have a great impact on channel statistics. Finally, the utility of the proposed model is validated by the excellent agreement between simulation results and measurements. [ABSTRACT FROM AUTHOR]

: Copyright of IEEE Transactions on Antennas & Propagation is the property of IEEE and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)