With the gradually increase of the application of new energy in microgrids, Electric Spring (ES), as a new type of distributed compensation power electronic device has been widely studied. The Generalized Electric Spring (G-ES) is an improved topology, and the space limitation problem in the traditional topology is solved. Because of the mode of G-ES use in the power grid, a reasonable solution to the voltage loss of the critical section feeder is needed. In this paper, the voltage balance equation based on the feedforward compensation coefficient is established, and a two cascade control strategy based on the equation is studied. The first stage of the two cascade control strategy is to use communication means to realize the allocation of feedforward compensation coefficients, and the second stage is to use the coefficients to realize feedforward fixed angle control. Simulation analysis shows that the proposed control strategy does not affect the control accuracy of the critical load (CL), and effectively improves the operational range of the G-ES.

In this letter, we consider a global stabilization problem for a class of feedforward systems by an event-triggered control. This is an extended work of [10] in a way that there are uncertain feedforward nonlinearity and time-varying input delay in the system. First, we show that the considered system is globally asymptotically stabilized by a proposed event-triggered controller with a gain-scaling factor. Then, we also show that the interexecution times can be enlarged by adjusting a gain-scaling factor. A simulation example is given for illustration.

We propose a deep learning-based model for classifying pathological voices using a convolutional neural network and a feedforward neural network. The model uses combinations of heterogeneous parameters, including mel-frequency cepstral coefficients, linear predictive cepstral coefficients and higher-order statistics. We validate the accuracy of this model using the Massachusetts Eye and Ear Infirmary (MEEI) voice disorder database and the Saarbruecken Voice Database (SVD). Our model achieved an accuracy of 99.3% for MEEI and 75.18% for SVD. This model achieved an accuracy that is 7.18% higher than that of competitive models in previous studies.

We realize a multicore erbium-doped fiber amplifier (MC-EDFA) with 2dB optical gain improvement (average) by recycling the residual 0.98μm pump light from the MC-EDF output. Eight-channel per core wavelength division multiplexed (WDM) Nyquist PM-16QAM optical signal amplification is demonstrated over a 40-minute period. Furthermore, we demonstrate the proposed MC-EDFA's stability by using it to amplify a Nyquist PM-16QAM signal and evaluating the resulting Q-factor variation. We found that our scheme contributes to reducing the total power consumption of MC-EDFAs in spatial division multiplexing (SDM)/WDM networks by up to 33.5%.

As real-time embedded systems are required to accommodate various tasks with different levels of criticality, scheduling algorithms for MC (Mixed-Criticality) systems have been widely studied in the real-time systems community. Most studies have focused on MC uniprocessor systems whereas there have been only a few studies to support MC multiprocessor systems. In particular, although the ZL (Zero-Laxity) policy has been known to an effective technique in improving the schedulability performance of base scheduling algorithms on SC (Single-Criticality) multiprocessor systems, the effectiveness of the ZL policy on MC multiprocessor systems has not been revealed to date. In this paper, we focus on realizing the potential of the ZL policy for MC multiprocessor systems, which is the first attempt. To this end, we design the ZL policy for MC multiprocessor systems, and apply the policy to EDF (Earliest Deadline First), yielding EDZL (Earliest Deadline first until Zero-Laxity) tailored for MC multiprocessor systems. Then, we develop a schedulability analysis for EDZL (as well as its base algorithm EDF) to support its timing guarantee. Our simulation results show a significant schedulability improvement of EDZL over EDF, demonstrating the effectiveness of the ZL policy for MC multiprocessor systems.

In this letter, we investigate the problem of feedforward timing estimation for burst-mode satellite communications. By analyzing the correlation property of frame header (FH) acquisition in the presence of sampling offset, a novel data-aided feedforward timing estimator that utilizes the correlation peaks for interpolating the fractional timing offset is proposed. Numerical results show that even under low signal-to-noise ratio (SNR) and small rolloff factor conditions, the proposed estimator can approach the modified Cramer-Rao bound (MCRB) closely. Furthermore, this estimator only requires two samples per symbol and can be implemented with low complexity with respect to conventional data-aided estimators.

This paper proposes 1-bit feedforward distortion compensation for digital radio frequency conversion (DRFC) with 1-bit bandpass delta-sigma modulation (BP-DSM). The 1-bit BP-DSM allows direct RF signal transmission from a digitally modulated signal. However, it has been previously reported that 1-bit digital pulse trains with non-ideal rectangle waveform cause spectrum regrowth. The proposed architecture adds a feedforward path with another 1-bit BP-DSM and so can cancel out the distortion components at any target carrier frequency. Both the main signal and the distortion compensation signal are 1-bit digital pulse trains and so no additional analog RF circuit is required for distortion compensation. Simulation results show that the proposed method holds the adjacent channel leakage ratio to 60dB for LTE signal transmission. A prototype of the proposed 1-bit DRFC with an additional 1-bit BP-DSM in the feedforward path shows an ACLR of 50dB, 4dB higher than that of the conventional 1-bit DRFC.

We report the adaptability of the burst-mode erbium-doped fiber amplifier (BM-EDFA) for uplink transmission of sharply rising analog radio-over-fiber (RoF) signals by using long-term evolution (LTE) -Advanced format on a mobile front-haul. Recent drastically increased mobile data traffic is boosting the demand for high-speed radio communication technologies for next-generation mobile services to enhance user experience. However, the latency become increasingly visible as serious issues. Analog RoF technology is a promising candidate for a next generation mobile front-haul to realize low latency. For the uplink, an RoF signal may rise sharply in response to a burst of in-coming radio signals. We propose that a newly developed BM-EDFA is applied for such a sharply rising RoF signal transmission. The BM-EDFA that we designed using enhanced intrinsic saturation power EDF to suppress the gain transient caused by received optical power fluctuations with optical feedback. The new BM-EDFA was designed for a wider linear output power range and lower NF than the previous BM-EDFA. The observed range of received optical power satisfying an error vector magnitude of less than 8%rms achieved over 16dB. We consider that our BM-EDFAs with wide linear ranges of output power will be a key device for the LTE-Advanced RoF uplink signal transmission via optical access networks for the next-generation mobile front-haul.

In this paper, we propose a flexible and high-capacity front-haul link for the uplink transmission of high-speed mobile signals using a cascade of radio-on-radio (RoR) and radio-over-fiber (RoF) systems. To emulate the cases that may occur in the uplink direction, we experimentally investigate the performance of superposing an uplink bursty LTE-A signal on the cascaded system using optical packet signal transmission. The performance of systems using different types of erbium-doped fiber amplifiers (EDFAs), including a high-transient EDFA, an automatic-gain-control EDFA, and a burst-mode (BM) EDFA is evaluated and compared. We confirm that the dynamic transience of the EDFAs has a significant influence on the signal performance. By using a BM-EDFA, we confirm successful transmission of the uplink packetized LTE-A signal on the cascaded system. Both the measured error vector magnitude and the received optical power range metrics exceed the requirements. We also estimate the maximum transmission range of the RoR link, and it is confirmed that a sufficiently long range could be achieved for the applications in mobile front-haul networks.

Computing and power resources are often limited in real-time embedded control systems. In this paper, we resolve the trade-off problem between control performance and power consumption in a real-time embedded control system with a dynamic voltage and frequency scaling (DVFS) uniprocessor implementing multiple control tasks. We formulate an optimization problem whose cost function depends on both the control performance and the power consumption. We introduce an adapter into the real-time embedded control system that adaptively assigns deadlines of jobs and clock frequencies according to the plant's stability and schedulability by solving the optimization problem. In numerical simulations, we show that the proposed adapter can reduce the power consumption while maintaining the control performance.

We propose multi-core erbium-doped fiber amplifiers for next-generation optical amplifiers utilized by space-division multiplexing technologies. Multi-core erbium-doped fiber amplifiers were studied widely as a means for overcoming exponential growth of internet traffic in the backbone network. We consider two approaches to excitation of erbium irons; One is core-pumping scheme, the other is cladding-pumping scheme. For a core-pumping configuration, we evaluate its applicability to future ultra long-haul network. In addition, we demonstrate that cladding-pumping configuration will enable reduction of power consumption, size, and cost because one multimode pumping laser diode can excite several cores simultaneously embedded in a common cladding and amplify several signals passed through the multi-core erbium-doped fiber cores.

This paper proposes the state observer design for feedforward nonlinear systems with delayed output. It is shown that by using the Lyapunov-Krasovskii functional, the proposed design method ensures the asymptotic stability of estimation error for an arbitrarily large output delay. Finally, an illustrative example is given in order to show the effectiveness of our design method.

For battery based real-time embedded systems, high performance to meet their real-time constraints and energy efficiency to extend battery life are both essential. Real-Time Dynamic Voltage Scaling (RT-DVS) has been a key technique to satisfy both requirements. This paper presents EccEDF (Enhanced ccEDF), an efficient algorithm based on ccEDF. ccEDF is one of the most simple but efficient RT-DVS algorithms. Its simple structure enables it to be easily and intuitively coupled with a real-time operating system without incurring any significant cost. ccEDF, however, overlooks an important factor in calculating the available slacks for reducing the operating frequency. It calculates the saved utilization simply by dividing the slack by the period without considering the time needed to run the task. If the elapsed time is considered, the maximum utilization saved by the slack on completion of the task can be found. The proposed EccEDF can precisely calculate the maximum unused utilization with consideration of the elapsed time while keeping the structural simplicity of ccEDF. Further, we analytically establish the feasibility of EccEDF using the fluid scheduling model. Our simulation results show that the proposed algorithm outperforms ccEDF in all simulations. A simulation shows that EccEDF consumes 27% less energy than ccEDF.

With the fast development of mobile communication technologies, mobile multimedia services like mobile Video on Demand (VOD) are becoming prevalent. However, VOD streaming requires dedicated bandwidth to satisfy Quality of Service (QoS), and the limited wireless bandwidth will become insufficient to support the increasing number of mobile VOD users. In order to solve the problem, this paper proposes a Call Admission Control (CAC) approach which can accept new users even when the system bandwidth is insufficient. Our approach also guarantees continuous playback for subscribers by taking into account the service end time and the delay bound of the users. Simulation results demonstrate that the proposed scheme can increase the number of concurrent users and reduce the connection blocking probability significantly without playback interruption.

It is shown that simple preprocessing on the reference signals in multichannel feedforward ANC system can improve the convergence performance of the adaptive ANC algorithm. A fast and efficient blind preprocessing algorithm in frequency domain is proposed to reduce the computational complexity even that the reference sensors are located far from the noise sources. The permutation problem at different frequency bin is also addressed and solved by an independent vector analysis algorithm. The basic principle and performance comparison are given to verify our conclusion.

This letter proposes a method for choosing the best quantized beamforming vector that represents a subcarrier group, for coordinated beamforming in the downlink of multiuser multiple input multiple output-orthogonal frequency division multiplexing systems. The correlation between subcarriers is exploited for reducing the feedforward overhead, while maximizing the sum rate.

We consider a stabilization problem of a class of input-delayed nonlinear systems that have not only feedforward, but also some non-feedforward nonlinearity. While there are some existing results that deal with input-delayed non-feedforward nonlinear systems, they often assume a small input delay. It has been often the case that for a large input delay, the results are limited to only feedforward systems. In this letter, combined with the LMI approach in [3] and the reduction method in [5], we show that some feedforward and non-feedforward systems with a large delay in the input can be stabilized via the proposed controller.

We present the recovery of 2.5 Gb/s synchronous 16-point quadrature amplitude modulation data in real-time for an linewidth-times-symbol-duration ratio of 0.00048 after transmission over 1.6 km standard single mode fiber.

We describe a series of system measurements investigating the performance of a burst-mode or transient-suppressed (TS)-EDFA, specifically designed to reduce the impact of gain transients in dynamic optical networks. We assess the performance of this TS-EDFA in a variety of network contexts. We compare the performance of the TS-EDFA with conventional amplifiers (C-EDFAs) and show its compatibility with supplementary gain control techniques. Finally, we measure gain-transient accumulation along long links using a recirculating transmission loop and show that, for packet-transmission, the number of hops is limited by accumulated transients for a C-EDFA, but limited by accumulated noise for the TS-EDFA.

In an embedded control system, control performances of each job depend on its latency and a control algorithm implemented in it. In order to adapt a job set to optimize control performances subject to schedulability, we design several types of control software for each job, which will be called versions, and select one version from them when the job is released. A real-time system where each job has several versions is called a multiversion real-time system. A benefit and a CPU utilization of a job depend on the versions. So, it is an important problem to select a version of each job so as to maximize the total benefit of the system subject to a schedulability condition. Such a problem will be called an optimal configuration problem. In this paper, we assume that each version is specified by the relative deadline, the execution time, and the benefit. We show that the optimal configuration problem is transformed to a maximum path length problem. We propose an optimal algorithm based on the forward dynamic programming. Moreover, we propose sub-optimal algorithms to reduce computation times. The efficiencies of the proposed algorithms are illustrated by simulations.