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This paper presents an observer to estimate grid voltage parameters, including frequency, amplitude and phase angle, for the variable frequency AC systems of more electric aircraft. Regarding grid voltage as a dynamic system with an unknown grid frequency, a parametric model is established, and then, an adaptive observer is developed to estimate grid voltage parameters with zero steady-state error...
Riding on the waves of deep neural networks, deep metric learning has achieved promising results in various tasks by using triplet network or Siamese network. Though the basic goal of making images from the same category closer than the ones from different categories is intuitive, it is hard to optimize the objective directly due to the quadratic or cubic sample size. Hard example mining is widely...
A robust governor is provided for Switched Reluctance Motor (SRM) in presence of nonlinearities, and strong coupling based on fuzzy PID control. At first, PID control and fuzzy control are constructed respectively for SRM, moreover, a series of comparison simulations are achieved including low speed, medium speed and high speed. Simulations show robust governor enables the system reduced by at least...
This paper presents an addition and multiplication computation cell using pulse train time amplifier (TA) and time register (TR), which could be easily extend to large-scale computation. The proposed pulse train TA exploits a delay cell ring to realize large input range. In TR a gated delay line with MOS capacitor is adopted to achieve both large number computation and high resolution. Finally, a...
With an increase in acceptance of face recognition systems, the desire for accurate biometric authentication — face recognition, has increased. Nowadays, the fundamental limitations of existing systems are, the vulnerabilities of false verification via a picture or simple video of a person. In this paper, it is inspired by how humans can perform reliable spoofing detection only based on the available...
YARN provides support for a variety of computing frameworks and different types of jobs, different types of computing tasks and jobs can be run on the YARN platform, different job types can divided into batch jobs and interactive jobs. As for the single job, it can be divided into three kinds: the small job, the middle job and the big job. Based on the different combinations and quantities of these...
A novel space vector PWM (SVPWM) strategy is proposed in this paper to balance the neutral-point voltage (NP) and the floating capacitor voltage for five-level active neutral-point-clamped (ANPC) converter. There are two different switching sequences in each small area. According to the NP offset, different switching sequences are used to control the NP voltage. Since the charge-discharge of the floating...
This paper proposes an improved energy management strategy for simultaneous power management of the photovoltaic grid-connected system with energy storage. Based on the DC bus voltage and the working states of grid, the PV system is divided into six working modes by the proposed energy management strategy. This can avoid the effect of grid failure on PV system, and achieve the optimal utilization...
Photovoltaic energy storage system meets the ever-growing demand for electricity, while ensuring the stability of power supply. Research of renewable energy-based microgrid system has become a hot topic, especially the study of Maximum Power Point Tracking (MPPT) and energy storage unit control strategies. This paper proposes an MPPT technique that combines gradient step size with conductance increment...
Improving the accuracy of power battery state of charge (SOC) estimation is an important basis for formulating and optimizing the control strategy of hybrid electric vehicle. Aiming at the problem of the traditional SOC large estimation error, a SOC estimation method based on self-recurrent wavelet neural network (SRWNN) is proposed. Firstly, the equivalent model of power battery and its SOC estimation...
Multiple vehicle detection and identification techniques have been widely applied to acquire road traffic information depending on various sensors, such as video camera, induction loop and magnetic sensor. Magnetic sensor can measure magnetic field distortion caused by the movement of vehicles and record reliable data. The precise volume and component of traffic flow can be obtained through reasonable...
With the rapid increase of the substation grade, the number of ultra-high voltage (UHV) transformer is increasing and the noise caused by the vibration of UHV transformer is becoming more and more serious. The vibration of UHV transformer is mainly generated from the magnetostrictive effect of the iron core and the action of the electromagnetic force of the winding. In this paper, the sound intensity...
A physical mechanism is presented which can generate coherent and tunable terahertz (THz) radiation. Due to the dramatical lifting of SPPs energy, the dispersion can cross the light line, thus, the SPPs excited by an moving electron beam can be transformed into THz radiation. The radiation power density is enhanced nearly three orders, up to 105 W/cm2. The radiation frequency can be widely tuned by...
Based on the parallel DTCs as delay cells, a 4-bit TDC with adjustable 0.7ps∼1.4ps resolution and 11ps∼22ps dynamic range is proposed in this paper. In this design, an extremely high resolution DTC is presented, achieving 15.6fs delay per LSB. By utilizing 16 DTCs which are adjusted to have the same time interval among two neighboring DTCs, a highly linear TDC is realized. To avoid the manual tuning,...
The terahertz optical response of a commensurate topologically insulator(TI)-graphene heterostructure is investigated. The interplay of interlayer hopping and topological band structure leads to additional selection rules for the inter band optical transition. The optical conductivity of such a system exhibits interesting features that do not occur in the two constituent surfaces separately. The transitions...
Graphene has been shown to be capable of supporting surface plasmon polaritons whose frequency is in the terahertz regime. We demonstrate that, due to the enhanced energy of surface plasmon in graphene, an optical bistability can occur in an air-graphene-dielectric structure.
With the rapid development of the power grid and the increase of power demand, the voltage level of the substation is improving rapidly. The noise caused by the transformer becomes a serious problem because it affects the health of the surrounding residents. In this paper, the noise of 1000kV transformer in Shanxi is measured and analyzed. The results show that the transformer noise has low frequency...
This paper presents a novel control strategy to reduce the DC-link voltage ripple for electrolytic capacitor-less PMSM drive system. By injecting the 3rd harmonic current into the driver system, the instantaneous power balance between the grid output power and the motor output power is achieved, so the DC-link voltage ripple is reduced obviously. For further improving the PMSM performance under DC-link...
Mechanical seals are widely used in the rotation parts in various applications, and the failure of them may cause serious consequences, such as pollution, corrosion, equipment retirement, heavy casualties and other economic losses. The leakage rate of mechanical seal is mainly determined by the film thickness between rotor ring and stator ring. Moreover, the film thickness is one of the most important...
Directly modulated semiconductor lasers for underwater wireless optical communication (UWOC) have limitations in output power and beam quality. Diode-pumped solid-state lasers (DPSSLs) have the merits of long lifetime, high stability, large power and good beam quality, which are promising to realize long-each UWOC. We compose a DPSSL with discrete components and measure its key parameters. The bandwidth...
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