SCOPE: Scalable Composite Optimization for Learning on Spark

Many machine learning models, such as logistic regression~(LR) and support vector machine~(SVM), can be formulated as composite optimization problems. Recently, many distributed stochastic optimization~(DSO) methods have been proposed to solve the large-scale composite optimization problems, which have shown better performance than traditional batch methods. However, most of these DSO methods are not scalable enough. In this paper, we propose a novel DSO method, called \underline{s}calable \underline{c}omposite \underline{op}timization for l\underline{e}arning~({SCOPE}), and implement it on the fault-tolerant distributed platform \mbox{Spark}. SCOPE is both computation-efficient and communication-efficient. Theoretical analysis shows that SCOPE is convergent with linear convergence rate when the objective function is convex. Furthermore, empirical results on real datasets show that SCOPE can outperform other state-of-the-art distributed learning methods on Spark, including both batch learning methods and DSO methods

Nonlinear robust controller design for thyristor controlled series compensation

Makalenin ilk sayfası mevcut.The problem of transient stability for a single machine infinite bus system with thyristor controlled series compensation (TCSC) is addressed in this paper. The system does not need to be linearized, and the damping coefficient is measured inaccurately. A nonlinear robust controller and a parameter updating law are obtained simultaneously based on modified adaptive backstepping sliding mode control and Lyapunov methods. The closed-loop error system is guaranteed to be asymptotically stable. The simulation results show that rapid speed response anal strong robustness can be obtained by the proposed method than the conventional adaptive backstepping and adaptive backstepping sliding mode control methods. The proposed method can be also be applied to other nonlinear systems with lower-triangular structure

Adaptive coordinated passivation control for generator excitation and thyristor controlled series compensation system

The problem of transient stability for a single machine infinite bus system with the generator excitation and thyristor controlled series compensation (TCSC) is addressed via the coordinated passivation method. The system does not need to be linearized. Two types of uncertainties, namely, the damping coefficient uncertainty and the modeling error of TCSC, are considered. First, an excitation control input and a parameter updating law are obtained simultaneously via adaptive back-stepping and Lyapunov methods to achieve stability of the zero dynamics subsystem. Then, a reactance modulated input is derived to ensure the feedback passivity of the whole system, based on which a stabilizing controller for the closed-loop system is designed. Simulation results show that the proposed controller produces better transient performance than the conventional direct feedback linearization controller

Maximally localized states and quantum corrections of black hole thermodynamics in the framework of a new generalized uncertainty principle

As a generalized uncertainty principle (GUP) leads to the effects of the minimal length of the order of the Planck scale and UV/IR mixing, some significant physical concepts and quantities are modified or corrected correspondingly. On the one hand, we derive the maximally localized states --- the physical states displaying the minimal length uncertainty associated with a new GUP proposed in our previous work. On the other hand, in the framework of this new GUP we calculate quantum corrections to the thermodynamic quantities of the Schwardzschild black hole, such as the Hawking temperature, the entropy, and the heat capacity, and give a remnant mass of the black hole at the end of the evaporation process. Moreover, we compare our results with that obtained in the frameworks of several other GUPs. In particular, we observe a significant difference between the situations with and without the consideration of the UV/IR mixing effect in the quantum corrections to the evaporation rate and the decay time. That is, the decay time can greatly be prolonged in the former case, which implies that the quantum correction from the UV/IR mixing effect may give rise to a radical rather than a tiny influence to the Hawking radiation.Comment: 27 pages, 10 figures, 4 tables; v2: 30 pages, sections 3-6 substantially revised but conclusions unchanged; v3: 27 pages, clarifications added; v4: 29 pages, clarifications and references added, final version to appear in Advances in High Energy Physic

Profit Maximizing Planning and Control of Battery Energy Storage Systems for Primary Frequency Control

We consider a two-level profit-maximizing strategy, including planning and control, for battery energy storage system (BESS) owners that participate in the primary frequency control (PFC) market. Specifically, the optimal BESS control minimizes the operating cost by keeping the state of charge (SoC) in an optimal range. Through rigorous analysis, we prove that the optimal BESS control is a “state-invariant” strategy in the sense that the optimal SoC range does not vary with the state of the system. As such, the optimal control strategy can be computed offline once and for all with very low complexity. Regarding the BESS planning, we prove that the the minimum operating cost is a decreasing convex function of the BESS energy capacity. This leads to the optimal BESS sizing that strikes a balance between the capital investment and operating cost. Our work here provides a useful theoretical framework for understanding the planning and control strategies that maximize the economic benefits of BESSs in ancillary service markets

Do Linear Dispersions of Classical Waves Mean Dirac Cones?

By using the \vec{k}\cdot\vec{p} method, we propose a first-principles theory to study the linear dispersions in phononic and photonic crystals. The theory reveals that only those linear dispersions created by doubly-degenerate states can be described by a reduced Hamiltonian that can be mapped into the Dirac Hamiltonian and possess a Berry phase of -\pi. Triply-degenerate states can also generate Dirac-like cone dispersions, but the wavefunctions transform like a spin-1 particle and the Berry phase is zero. Our theory is capable of predicting accurately the linear slopes of Dirac/Dirac-like cones at various symmetry points in a Brilliouin zone, independent of frequency and lattice structure

Bright Soliton Solution of (1+1)-Dimensional Quantum System with Power-Law Dependent Nonlinearity

We study the nonlinear dynamics of (1+1)-dimensional quantum system in power-law dependent media based on the nonlinear Schrödinger equation (NLSE) incorporating power-law dependent nonlinearity, linear attenuation, self-steepening terms, and third-order dispersion term. The analytical bright soliton solution of this NLSE is derived via the F-expansion method. The key feature of the bright soliton solution is pictorially demonstrated, which together with typical analytical formulation of the soliton solution shows the applicability of our theoretical treatment