- 标题
- 摘要
- 关键词
- 实验方案
- 产品
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[IEEE 2018 OCEANS - MTS/IEEE Kobe Techno-Ocean (OTO) - Kobe (2018.5.28-2018.5.31)] 2018 OCEANS - MTS/IEEE Kobe Techno-Oceans (OTO) - DEMON Spectrum Extraction Method Using Empirical Mode Decomposition
摘要： The noise radiated by a ship is modulated at a rate dictated by some parameters of the propeller and engine (number of blades, rotational speed). Evaluation of that modulation provides information on the ship, such as the shaft rotation frequency, that can be used for ship classification. The method for estimation of the envelope modulation is known as DEMON (Detection of Envelope Modulation on Noise). Traditionally, the ship noise is bandpass filtered in different frequency bands before the envelope analysis. The bandwidth and the number of the bandpass filters is not known. In this paper a new DEMON spectrum extraction method is proposed using empirical mode decomposition (EMD), in which the band number and width are automatically determined. In performance test, a feedforward neural network is used for 5 kinds ship noise classification, and the percentage of correct classification reaches 91.6%.
关键词： DEMON,empirical mode decomposition,Detection of envelope modulation on noise,feedforward neural network,EMD
更新于2025-09-23 15:22:29
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[IEEE 2018 IEEE 3rd Optoelectronics Global Conference (OGC) - Shenzhen (2018.9.4-2018.9.7)] 2018 IEEE 3rd Optoelectronics Global Conference (OGC) - Signal Quality Improvement in Optical PPM-CDMA Systems Based SIC Scheme
摘要： Optical pulse position modulation-code division multiple access (PPM-CDMA) system with an interference theoretically analyzed. Successive interference cancellation (SIC) scheme has the ability to suppress the overlapping between the users by subtracting the strongest one from the original received signals one by one until all users detected. Different optical codes have been used for the comparison purpose; results show that the system with SIC scheme using modified quadratic congruence codes has better performance than the system using modified prime code as signature codes. In addition, the system with SIC scheme significantly superior to the one without SIC scheme.
关键词： code division multiple access,optical communication,interference cancellation,pulse position modulation
更新于2025-09-23 15:22:29
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[IEEE 2018 IEEE International Students' Conference on Electrical, Electronics and Computer Science (SCEECS) - Bhopal (2018.2.24-2018.2.25)] 2018 IEEE International Students' Conference on Electrical, Electronics and Computer Science (SCEECS) - Solar Power Based Three-Level Neutral Clamped Inverter Fed DTFC-SVM of an IM Drive
摘要： This paper presents a solar power based three-level neutral clamped inverter (3LNCI) fed induction motor drive (IMD) with space vector modulation based direct torque and flux control (DTFC-SVM) for the water pumping applications. Due to the robustness and the flexible operating characteristics, induction motor is most suitable for water pump system. A DC/DC boost converter along with perturb and observe method of maximum power point tracking (MPPT) control technique is employed to draw sophisticated power from the solar photovoltaic (PV) array. The DTFC-SVM of an IMD using 3LNCI is proposed for improving performance and reducing the ripple contents of torque, flux and stator currents. The proposed method is simulated in MATLAB/SIMULINK environment and simulated results are presented under various operating conditions.
关键词： photovoltaic array,space vector modulation,induction motor drive,three-level diode clamped inverter,Direct torque and flux control
更新于2025-09-23 15:22:29
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Evaluation of Low-Temperature Saturation Velocity in β -(Al?Ga???)?O?/Ga?O? Modulation-Doped Field-Effect Transistors
摘要： We report on the high-field transport characteristics and saturation velocity in a modulation-doped β-(AlxGa1?x)2O3/Ga2O3 heterostructure. The formation of a 2-D electron gas (2DEG) in the modulation-doped structure was confirmed from the Hall measurements, and the 2DEG channel mobility increased from 143 cm2/V·s at room temperature to 1520 cm2/V·s at 50 K. The high electron mobility at 50 K made it feasible to achieve velocity saturation inside the channel. The saturation velocity was estimated based on both pulsed current–voltage measurements and small-signal radio frequency (RF) measurements. The measured velocity–field profile suggested a saturation velocity above 1.1 × 107 cm/s at 50 K. The small-signal RF characteristics were measured for the fabricated modulation-doped field-effect transistors with a Pt-based Schottky contact. The current gain cutoff frequency (ft) and maximum oscillation frequency (fmax) showed significant increases from 4.0/11.8 GHz at room temperature to 17.4/40.8 GHz at 50 K for the device with gate length of LG = 0.61 μm. The analysis of the low temperature ft based on device simulations indicated a peak velocity of 1.2 × 107 cm/s. The three-terminal off-state breakdown measurement further suggested an average breakdown field of 3.22 MV/cm. The high saturation velocity and high breakdown field in β-Ga2O3 make it a promising candidate for high-power and high-frequency device applications.
关键词： mobility,β-Ga2O3,modulation-doped field-effect transistor (MODFET),2-D electron gas (2DEG),saturation velocity,high breakdown field
更新于2025-09-23 15:22:29
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Manipulation of nanomechanical resonator via shaking optical frequency
摘要： Cavity optomechanical system has made rapid advances in the past decades, which is mainly used to study the macroscopic quantum effects of the micromechanical resonators, such as the ground-state cooling of the mechanical resonator, mechanical squeezing, entanglement, macroscopic quantum superposition, etc. Owing to the unique advantages of optomechanical systems, numerous potential applications have been proposed, e.g., the ultrahigh precision metrology, exploring the quantum-classical boundary, and studying the weak signal transducer. The progress of the gravitational-wave detection is a great example for the application of optomechanics. In recent years, the periodically modulated optomechanical systems have attracted significant attention, which have been used to study various macroscopic quantum effects. However, in those modulation proposals, most of them focus on modulating the driven laser field, which results in the first-order moments of the system operators and the effective optomechanical coupling changing periodically to achieve and study some quantum effects. On the other hand, the frequency modulated quantum systems also exhibit a rich behavior and display nonequilibrium properties that are absent in their static counterparts, such as the phenomena of motional averaging and narrowing, Landau–Zener–Stückelberg–Majorana interference, and the formation of dressed states with the appearance of sidebands in the spectrum. However, in cavity optomechanical systems, the study of the influence coming from the frequency modulation is relatively rare to date. In this paper, we study an usual cavity optomechanical system where the frequency of the optical mode is shaken periodically. As we all know, the stability of optomechanical systems is closely related to the effective optomechanical coupling strength. For an excessively large coupling strength, the optomechanical systems are unstable and the studying is also meaningless. However, we find that the shaking optical mode can reduce the effective optomechanical coupling strength arbitrarily when the shaking frequency is much larger than the mechanical resonator frequency, and the deeply physical mechanism can be explained through the Raman-scattering and frequency domain pictures. The result indicates that it will be possible to study the steady quantum effects of optomechanical system even with strong coupling where the standard optomechanical systems without frequency modulation are always unstable. In order to verify the above analyses, we study the ground-state cooling of the mechanical resonator and the entanglement between the optical and mechanical modes in the conventional unstable region, and the results indicate that the final mean phonon number and entanglement not only can be achieved but also can be modulated by the optical shaking parameters. Our proposal provides a method to study the macroscopic quantum effects even in conventional unstable region.
关键词： micromechanical resonator cooling,entanglement,frequency modulation,optomechanics
更新于2025-09-23 15:22:29
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On the Complexity Reduction of the 2nd-order Volterra Nonlinear Equalizer for IM/DD systems
摘要： To cope with the various nonlinear signal distortions in IM/DD transmission systems, a theoretical analysis on the Volterra nonlinear equalizer (VNLE) is provided, focusing on computational complexity aspects. The analysis yields a simple reduced-complexity scheme for the 2nd-order VNLE (R2-VNLE) based on a performance-complexity trade-off. An experimental verification is performed with single-sideband 28-GBaud PAM-4 electro-absorption modulated signals, generated by a distributed-feedback laser, over transmission distances of up to 80-km of standard single-mode fiber in the C-band. A comparison of the results for different equalization schemes, including a signal-signal beat interference mitigation technique, shows superior performance for the R2-VNLE.
关键词： PAM-4,Volterra filter,direct detection,Nonlinear equalization,optical interconnects,intensity modulation
更新于2025-09-23 15:22:29
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Performance analysis of adaptive OFDM modulation scheme in VLC vehicular communication network in realistic noise environment
摘要： Optical wireless communications (OWC) has emerged as a strong candidate for wireless communications, due to the capacity limitation in the radio frequency (RF) spectrum. Especially visible light communication (VLC) has great potential for short-range outdoor vehicular communications, as vehicle LED lights also transmit data. However, outdoor VLC channels vary fast and, experience multipath scattering and reflection resulting in time domain dispersion. Outdoor VLC links are also subjected to high levels of ambient noise, especially from the sun. Orthogonal frequency-division multiplexing (OFDM), which has proven robustness to multi path fading and noise effects in RF links can also be deployed in VLC links. In this paper, optical OFDM (O-OFDM) along with adaptive modulation scheme is investigated in VLC for vehicle to vehicle (V2V) communications. A (2 × 2) multiple input multiple output (MIMO) channel, with multiple polarimetric bidirectional reflections and realistic sunlight interference is considered. Two schemes of O-OFDM; direct current biased optical OFDM (DCO-OFDM) and asymmetrically clipped optical OFDM (ACO-OFDM) are investigated. Simulation results of the proposed model show increase in data rates up to 50 Mbps along with reduced bit error rate (BER) under both line of sight (LOS) and non-LOS and high noise conditions.
关键词： V2V,Optical OFDM,Adaptive modulation,VLC,Bit loading,MIMO
更新于2025-09-23 15:22:29
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Secure Point-to-Multipoint Communication Using the Spread Spectrum Assisted Orthogonal Frequency Diverse Array in Free Space
摘要： Wireless communication security has been increasingly important nowadays. Directional modulation (DM) is seen as a promising wireless physical layer security technology. Traditional DM is a transmit-side technology that projects digitally modulated information signals in the desired directions (or at the desired locations) while simultaneously distorting the constellation formats of the same signals in other directions (or at all other locations). However, these directly exposed digitally modulated information signals are easily intercepted by eavesdroppers along the desired directions (or around the desired locations). A new DM scheme for secure point-to-multipoint communication based on the spread spectrum assisted orthogonal frequency diverse array (short for SS-OFDA-M-DM) is proposed in this paper. It can achieve point-to-multipoint secure communication for multiple cooperative receivers at different locations. In the proposed SS-OFDA-M-DM scheme, only cooperative users that use specific DM receivers with right spread spectrum parameters can retrieve right symbols. Eavesdroppers without knowledge of spread spectrum parameters cannot intercept useful signals directly at the desired locations. Moreover, they cannot receive normal symbols at other locations either even if the right spread spectrum parameters are known. Numerical simulation results verify the validity of our proposed scheme.
关键词： Frequency diverse array,Spread spectrum,Directional modulation,Secure point-to-multipoint communication
更新于2025-09-23 15:22:29
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A 65 nm 19.1-to-20.4 GHz Sigma-Delta Fractional-N Frequency Synthesizer with Two-Point Modulation for FMCW Radar Applications
摘要： A 19.1-to-20.4 GHz sigma-delta fractional-N frequency synthesizer with two-point modulation (TPM) for frequency modulated continuous wave (FMCW) radar applications is presented. The FMCW synthesizer proposes a digital and voltage controlled oscillator (D/VCO) with large continuous frequency tuning range and small digital controlled oscillator (DCO) gain variation to support TPM. By using TPM technique, it avoids the correlation between loop bandwidth and chirp slope, which is beneficial to fast chirp, phase noise and linearity. The start frequency, bandwidth and slope of the FMCW signal are all reconfigurable independently. The FMCW synthesizer achieves a measured phase noise of ?93.32 dBc/Hz at 1MHz offset from a 19.25 GHz carrier and less than 10 μs locking time. The root-mean-square (RMS) frequency error is only 112 kHz with 94 kHz/μs chirp slope, and 761 kHz with a fast slope of 9.725 MHz/μs respectively. Implemented in 65 nm CMOS process, the synthesizer consumes 74.3 mW with output buffer.
关键词： FMCW radar,fractional-N,two-point modulation,CMOS,phase locked loop,frequency synthesizer
更新于2025-09-23 15:22:29
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Diffraction Focal Position and Vector Diffraction Theory for Micro Holographic Storage Systems
摘要： In this study, we proposed a method to determine the optimal focal position for micro-holographic storage systems, using vector diffraction theory; the theory provides exact solutions when the numerical aperture (NA) exceeds 0.6. The best diffraction focus was determined by the position and wavelength corresponding to minimal spherical aberration. The calculated refractive index modulation, polarization illumination, and boundary conditions at the interface of different media were analyzed. From the results of our analysis, we could confirm the size of micrograting as a function of NA and wavelength, based on vector diffraction theory, compared with scalar diffraction theory which defines the micrograting by . To demonstrate our analysis, we adapted an optical alignment method using a Twyman-Green interferometer, and could obtain good agreement between analysis and experimental results.
关键词： microholographic storage system,diffraction focus,vector diffraction theory,scalar diffraction theory,diffraction efficiency,refractive index modulation,interferogram,polarization
更新于2025-09-23 15:22:29