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In this paper, the non isolated grid connected inverter control strategy is adopted. The simulation model of photovoltaic grid connected inverter is built in MATLAB. Realize the same frequency and phase of grid connected current and grid voltage, the sine degree of grid connected current waveform is better, and realize the islanding detection function. In the experiment platform, the control idea is further verified, and the simulation is proved to be correct.

The basic elements of internal solitary waves (ISWs) were obtained by vertically placed sensors in the laboratory experiment and in-situ observation. The vertical characteristics of the amplitude and waveform are analysed experimentally and observationally. Then the experimental and observational results were compared with the theoretical model. The study shows that the experimental amplitude-frequency relationship is closer to that in the two-layer model while the observational amplitude-frequency relationship is more approaching to that in the continuously stratified model. Experimental and observational results reveal that the amplitude of ISWs increase first and then decrease with an increasing depth. The sech 2 function of the KdV theory can describe the waveforms of ISWs at different depths well.

Based on new signal generation technologies such as vector signal modulation and arbitrary waveform editing and playback, the transmitter resources are multiplexed by each signal component at the same time or sharing time to generate flexible and dense composite signals and solve the problem of complex electromagnetic environment construction under the limited hardware.

Background: Spinal cord stimulation (SCS) has emerged as state-of-the-art evidence-based treatment for chronic intractable pain related to spinal and peripheral nerve disorders. Traditionally delivered as steady-state, paraesthesia-producing electrical stimulation, newer technology has augmented the SCS option and outcome in the last decade. Objective: To present an overview of the traditional and newer SCS waveforms. Materials and Methods: We present a short literature review of SCS waveforms in reference to newer waveforms and describing paraesthesia-free, high frequency, and burst stimulation methods as well as advances in waveform paradigms and programming modalities. Pertinent literature was reviewed, especially in the context of evolution in the waveforms of SCS and stimulation parameters. Results: Conventional tonic SCS remains one of the most utilized and clinically validated SCS waveforms. Newer waveforms such as burst stimulation, high-frequency stimulation, and the sub-perception SCS have emerged in the last decades with favorable results with no or minimal paraesthesia, including in cases otherwise intractable to conventional tonic SCS. The recent evolution and experience of closed-loop SCS is promising and appealing. The experience and validation of the newer SCS waveforms, however, remain limited but optimistic. Conclusions: Advances in SCS device technology and waveforms have improved patient outcomes, leading to its increased utilization of SCS for chronic pain. These improvements and the development of closed-loop SCS have been increasingly promising development and foster a clinical translation of improved pain relief as the years of research and clinical study beyond conventional SCS waveform come to fruition.

Coastal zones are challenging areas for sensing by satellite altimeters because reflected signals from non-water surfaces and from calm sea surfaces in small bays and ports inside the radar footprint lead to erroneous powers in return waveforms. Accordingly, these contaminated waveforms do not follow the so-called Brown model in conventional retracking algorithms and fail to derive qualified ranges. Consequently, the estimated water level is erroneous as well. Therefore, selecting an optimized retracker for post-processing waveforms is significantly important to achieve a qualified water level estimation. To find the optimized retracker, we employed a methodology to minimize the effect of erroneous powers on retracked range corrections. To this end, two new approaches were presented, one based on a waveform decontamination method and the other based on a waveform modification method. We considered the first meaningful sub-waveforms in the decontaminated waveforms and in the modified waveforms to be processed with a threshold retracker. To assess their performance, we also retracked the decontaminated and modified full-waveforms. The first meaningful sub-waveform and full-waveform in the original waveforms were retracked to compare the performance of the modified and decontaminated waveform retracking with the original waveform retracking. To compare the results of our sub-waveform retracking algorithms with those of external sub-waveform retracking algorithms, the (Adaptive Leading Edge Sub-waveform) ALES database was also used. In our retracking scenarios, we used the Sentinel-3A SRAL Altimeter to estimate the water levels over the study area within 10 km from the coastlines in both the Persian Gulf and the Bay of Biscay from June 2016 to October 2020. The water levels from processing L2 products were estimated as well. We evaluated our retracking scenarios and L2, as well as the ALES processing results, against the tide gauges. Our analysis showed that within 0–10 km from the coast, the first meaningful sub-waveform of the decontaminated waveforms had the best performance. We reached maximum RMS improvements in this scenario of 53% and 86% over the Persian Gulf and the Bay of Biscay, respectively, in comparison with L2 processing. Over these distances from the coast, the first sub-waveform from the original waveforms and the modified waveforms stayed in the second and third order of performance. The ALES database with an RMS ranging from 13 to 51 cm had a worse performance than all of our sub-waveform retracking scenarios.

For the underwater acoustic (UAC) positioning system based on continuous waveform signal, the time-delay estimation of the Line-of-sight (Los) is not robust under the UAC strongly time-varying multipath channel. So an anti-multipath time-delay detection algorithm based on dual-delta (DD) correlators is proposed in this paper to address the issue. The algorithm uses a differential processing code-phase discriminator model to improve the traditional delay-locked-loop (DLL) time-delay detection algorithm, and combines it with the signal tracking loop adapted to the UAC channel condition to estimate time-delay. Theoretical analysis indicates that due to the reduction of local code interval and the differential processing operation, the proposed algorithm effectively mitigates the effect of time-varying multipath signals on time-delay estimation compared with conventional methods. Simulation analysis further demonstrates that the proposed algorithm can robustly detect the Los and achieve high-precision time-delay estimation under the time-varying multipath channel. The algorithm shows great potential for practical applications.

Chopper systems are typically used to provide beam time structure and ensure the safety of accelerator operation by deflecting the beam away. The reliability of conventional choppers is entirely based on high-voltage (HV) pulsed power supplies. However, when the power supply fails to charge the electrostatic deflection plate, the beam cannot be cut off, and it will enter the downstream accelerator. To meet the strict beam stopping time requirements of the China Initiative Accelerator Driven System (CiADS), novel E × B chopper design has been developed based on a permanent magnet and an electrostatic deflection plate. This design not only ensures the safety of the accelerator but also provides the necessary pulse waveform. The device is small, highly reliable, and suitable for most accelerators. Moreover, beam dynamics simulations have been conducted to evaluate the chopper’s influence on beam quality, and its beam cutting capability has been analyzed.

Calibration for Heterodyne Laser-Doppler Vibrometers (HLDV) is important for its accuracy and reliability. ISO 166063-41 provides primary and secondary calibration specifications for HLDV only in the frequency range from 0.4Hz to 50kHz, which can’t meet current demand for higher frequency. To be specific, the vibration exciter limits calibration frequency to a higher range. With this in mind, the electric calibration is presented. As a substitution method, the high precision arbitrary waveform generator replaces the optical module to output synthesized Doppler heterodyne signals which can cover all the required frequency. In addition, a commercial demodulator is used for calibration in the frequency range up to 1MHz. By theoretical introduction and experimental verification, this method offers significant improvement and thus potential over existing methods for HLDV calibration.