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We demonstrate experimentally spontaneous chirality in a whispering-gallery microresonator. Above an input threshold, the intensities of clockwise and counterclockwise propagating waves grow unbalanced, due to the Kerr-nonlinearity-modulated coupling between the counter-propagating waves.
We develop a cost-effective and highly reproducible method for manufacturing large-area dielectric metasurfaces. A high-performance silicon metasurface for generating cylindrical polarized vector beam is demonstrated as an example.
The electro-optic crosstalk between two parallel silicon Mach-Zehnder modulators is characterized. Up to 1.6 dB power penalty is observed for 36-Gb/s on-off-keying signals with a ∼-20 dB crosstalk, posing challenge to dense photonic integration.
It is a common issue to remove undesirable objects during reconstruction. The holes left behind are then needed to be given plausible information for the integrity. To complete the missing part of a 3D map generated from stereo inputs, the task can be separated into two operations which are repairing the color image and the depth map. In this paper, we design and release a specialized stereo dataset...
This paper proposes a transient modeling and analysis method for the fractional-order DC-DC converters in continuous conduction mode (CCM), in which a fractional-order Buck converter is taken as an example. By extending the usage of equivalent small parameter method (ESP), the converter is modeled by a general state vector differential equation. Then by adopting the principle of harmonic balance,...
This paper presents a new technique to optimize the efficiency of the Cascaded Buck-Boost (CBB) converters by using adaptive switching frequency selection algorithm. Such bidirectional DC-DC CBB topology is typically deployed in PV-Battery systems. A precise loss-model that accounts for component nonlinearities is developed in which an optimal switching frequency is chosen that corresponds to the...
Inverters are widely applied in industrial fields. To acquire the analytical solution of sinusoidal pulse width modulation (SPWM) Single-phase inverters, a traditional harmonic balance based method is extended, in which the double Fourier transform is used to describe the nonlinear switching function of the converter. Thus the steady-state periodic solution of the inverter can be obtained by our approach...
Reverse engineering binary code is notoriously difficult and, especially, understanding a binary's dynamic data structures. Existing data structure analyzers are limited wrt. program comprehension: they do not detect complex structures such as skip lists, or lists running through nodes of different types such as in the Linux kernel's cyclic doubly-linked list. They also do not reveal complex parent-child...
We give an adaptive algorithm that tests whether an unknown Boolean function f: {0,1}^n -≈ {0, 1} is unate (i.e. every variable of f is either non-decreasing or non-increasing) or ≥-far from unate with one-sided error and O(n^{3/4}/≥^2) many queries. This improves on the best adaptive O(n/≥)-query algorithm from Baleshzar, Chakrabarty, Pallavoor, Raskhodnikova...
Spontaneous chiral symmetry breaking is a ubiquitous property in nature and diverse fields of modern physics. However, such symmetry breaking has been elusive experimentally in the optical systems, which usually demands multiple identical subsystems [1]. As a prominent photonic device, the ultrahigh-Q whispering-gallery mode (WGM) microresonator supports clockwise (CW) and counterclockwise (CCW) propagating...
Large scale incorporation of wind farms may cause the issue of low inertia and lack of ability of frequency regulation in power systems. In this paper, the frequency control scheme of variable speed wind turbine under the whole wind condition was proposed. According to the reserve capacity required for the frequency regulation of the variable speed wind turbine, the de-loading scheme of the wind turbine...
The concept and technologies of fractional calculus have been increasingly applied to model and design circuits and electrical elements. In this work, by combining the principle of harmonic balance and equivalent small parameter method, we develop a new method of steady-state analysis for fractional-order DC-DC converters in discontinuous conduction mode (DCM). The effectiveness of the proposed scheme...
In this paper, we present a multi-sensory terrain classification algorithm with a generalized terrain representation using semantic and geometric features. We compute geometric features from lidar point clouds and extract pixel-wise semantic labels from a fully convolutional network that is trained using a dataset with a strong focus on urban navigation. We use data augmentation to overcome the biases...
While adding new capabilities, the distributed energy resource proliferation raises great concern about challenges such as dynamic fluctuations of voltages. For example, in a volatile setting with highly uncertain renewable generation and customer consumption, it is challenging to provide reliable power and voltage prediction for operational planning purposes to mitigate risks, e.g., over-voltages...
In dq-frame current control scheme for single-phase grid-connected inverters, an orthogonal signal generation (OSG) block is required to generate a virtual orthogonal signal. The OSG block makes the control system complicated and introduces extra disturbance, which deteriorates the dynamic performance. This paper presents a simplified dq-frame current controller for single-phase grid-connected inverters...
This paper presents a sensor-less control method for a stand-alone ship shaft generation system based on brushless doubly-fed machine (BDFM) with a novel wound rotor structure. A speed estimation based on the Model Reference Adaptive is introduced into the control winding field-oriented control method. The control block diagram is set up including the adjustable model and reference model and relevant...
In the applications like aerospace, it is very important to drive the motor with high precision and high efficiency. The traditional switching inverter drives output pulse mode voltage which results in lots of harmonics and influences the stability of motor drives. A multilevel-switching-linear hybrid (MSLH) scheme is proposed in the paper for the permanent magnet synchronous motor (PMSM) drives....
In this paper, two modified space vector pulse width modulation (SVPWM) methods are presented. The relationship of them is comprehensively studied. A variable factor ko is introduced into the unified voltage modulation method. Due to factor ko, the time duration of application of two zero state vectors is made changeable from 0 to 100% over the sampling period for their combined application, which...
With the accelerating process of urbanization, rural migrant workers flood into the cities. Research projects that aim at resettlement and employment promotion of these workers, social stability, as well as economic development have drawn attention of government and scholars alike. With respect to the matching problems of urban employment of rural migrant workers, grey incidence analysis and two-sided...
Prediction of aircraft Auxiliary Power Unit (APU) degradation plays an important role in aircraft health monitoring and condition-based maintenance. Due to complexity of the system and the variability and stochastic nature of the working environment, the degradation of the APU engine is hardly to be described by traditional deterministic time series analysis. Alternatively, advanced probabilistic...
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