Higher-order Power Research Articles

One Kind of Band-Gap Voltage Reference Source with Piecewise High-Order Temperature Compensation and Power Supply Rejection Ratio

This paper designed a new band-gap voltage reference circuit with two-stage temperature compensation.It realizes non-linear temperature compensation by using NMOS-pipe leakage current and increases the power supply rejection ratio of the band-gap voltage reference source by introducing negative feedback between the operational amplifier and the power supply. What is more, the paper simulates the band-gap voltage reference source based on CSMC 0.5μm CMOS technique. The result as follow: the band-gap voltage reference source has the temperature coefficient of 8.2ppm/oC among-40-120oC with the supply voltage of 3V, the low-frequency power supply rejection ratio is 83dBat 27oC and the power supply rejection ratio is 71dB in 1KHz, the output voltage regulation is 1.05mV/V in the supply voltage range from 2.4V to 5V.

A Robust Passive Damping Method for LLCL-Filter-Based Grid-Tied Inverters to Minimize the Effect of Grid Harmonic Voltages

In order to minimize the effect of the grid harmonic voltages, harmonic compensation is usually adopted for a grid-tied inverter. However, a large variation of the grid inductance challenges the system stability in case a high-order passive filter is used to connect an inverter to the grid. Although in theory, an adaptive controller can solve this problem, but in such a case the grid inductance may need to be detected online, which will complicate the control system. This paper investigates the relationship between the maximum gain of the controller that still keeps the system stable and the Q-factor for a grid-tied inverter with an RL series or an RC parallel damped high-order power filter. Then, a robust passive damping method for LLCL-filter-based grid-tied inverters is proposed, which effectively can suppress the possible resonances even if the grid inductance varies in a wide range. Simulation and experimental results are in good agreement with the theoretical analysis.

2D DOA Estimation Using Sparse Representation of Higher-Order Power of Covariance Matrix

A novel two-dimensional (2D) direction-of-arrival (DOA) estimation algorithm utilizing a sparse signal representation of higher-order power of covariance matrix is proposed. Through applying the higher-order power of covariance matrix to construct a new sparse decomposition vector, this algorithm avoids the estimation of incident signal number and eigenvalue decomposition. And the hierarchical granularity-dictionary is studied, which forms the over-complete dictionary adaptively in the light of source signals’ distribution. Compared with MUSIC and L1-SVD, this algorithm not only provides a better 2D DOA performance but also possesses the capability of coherent signals estimation. Theoretical analysis and simulation results demonstrate the validity and robust of the proposed algorithm.

A DOA Estimation Algorithm in OFDM Radar-Communication System for Vehicular Application

According to IEEE Std 802.11p, a fast DOA estimation algorithm of multiple targets based on beam-forming techniques in OFDM radar-communication system for vehicular applications is discussed in this paper. The proposed algorithm has reduced computational complexity utilizing high order power of the inverse spatial covariance matrix without eigen-decomposition. Simulation results demonstrate it is suitable for vehicular application.

Ternary Interaction Parameters in Calphad Solution Models

For random, diluted, multicomponent solutions, the excess chemical potentials can be expanded in power series of the composition, with coefficients that are pressure- and temperature-dependent. For a binary system, this approach is equivalent to using polynomial truncated expansions, such as the Redlich-Kister series for describing integral thermodynamic quantities. For ternary systems, an equivalent expansion of the excess chemical potentials clearly justifies the inclusion of ternary interaction parameters, which arise naturally in the form of correction terms in higher-order power expansions. To demonstrate this, we carry out truncated polynomial expansions of the excess chemical potential up to the sixth power of the composition variables.

High performance hysteresis modulation technique for high‐order PFC circuits

A simple control strategy to reduce the total harmonic distortion in single-stage high-order power factor correction AC–DC circuits is presented. A variable hysteresis window is used to improve the system performance near the zero crossing of the input current by increasing the switching frequency near this region.

An Adaptive Shifted Power Method for Computing Generalized Tensor Eigenpairs

Several tensor eigenpair definitions have been put forth in the past decade, but these can all be unified under generalized tensor eigenpair framework, introduced by Chang, Pearson, and Zhang (2009). Given mth-order, n-dimensional real-valued symmetric tensors A and B, the goal is to find $\lambda \in R$ and $x \in R^n$, $x \neq 0$, such that $Ax^{m-1} = \lambda Bx^{m-1}$. Different choices for B yield different versions of the tensor eigenvalue problem. We present our generalized eigenproblem adaptive power method (GEAP) method for solving the problem, which is an extension of the shifted symmetric higher-order power method (SS-HOPM) for finding Z-eigenpairs. A major drawback of SS-HOPM was that its performance depended in choosing an appropriate shift, but our GEAP method also includes an adaptive method for choosing the shift automatically.

Cooperative output‐synchronisation of networked high‐order power integrators

In this study, we have considered the cooperative output synchronisation problem of non-linear multi-agent system. The dynamic of each agent in the network is a class of genuinely non-linear system, named as high-order power integrator that may be uncontrollable after linearisation around the origin. Disturbance is considered in the input channel of each agent as well. Combined Graph theory with the method of adding a power integrator, a distributed controller is designed recursively for each agent to achieve the control objective. The distributed controller of each agent has three parts: state feedback of itself, output information of its neighbours and an adaptive disturbance compensator. It is proved that when the undirected graph is connected, all agents’ outputs in the network can be synchronised, that is, cooperative output synchronisation is achieved. Simulation result is presented to verify its effectiveness.

B → D* zero-recoil formfactor and the heavy quark expansion in QCD: a systematic study

We present a QCD analysis of heavy quark mesons focussing on the B -> D* formfactor at zero recoil, F_D*(1). An advanced treatment of the perturbative corrections in the Wilsonian approach is presented. We estimate the higher-order power corrections to the OPE sum rule and describe a refined analysis of the nonresonant continuum contribution. In the framework of a model-independent approach, we show that the inelastic contribution in the phenomenological part of the OPE is related to the mQ-dependence of the hyperfine splitting and conclude that the former is large, lowering the prediction for F_D*(1) down to about 0.86. This likewise implies an enhanced yield of radial and D-wave charm excitations in semileptonic B decays and alleviates the problem with the inclusive yield of the wide excited states. We also apply the approach to the expectation values of dimension 7 and 8 local operators and to a few other issues in the heavy quark expansion.

Compact vortexlike solutions in a generalized Born-Infeld model

We study vortexlike solutions in a generalized Born-Infeld model. The model is driven by two distinct parameters, one which deals with the Born-Infeld term, and the other, which controls the presence of high-order power term in the covariant derivative of the Higgs field. We numerically solve the equations of motion and depict the main vortex features, for several values of the two parameters of the model. The results indicate the presence of compact vortex, when the parameter responsible for the high-order power in the derivative increases to sufficiently large values.

Analytical transfer matrix of a quadrupole fringe

The analytical linear transfer matrices for different quadrupole fringes including quadratic, high order power and exponential models are deduced in this paper. As an example, the transfer matrices of the quadrupole BEPCII 105Q are computed for the above three models and compared with hard edge and slice-by-slice models in cases of near 60° and 90° FODO cells. These models' results are much better than the hard edge model's, and can meet the requirement of accurate calculation.

Shifted Power Method for Computing Tensor Eigenpairs

Recent work on eigenvalues and eigenvectors for tensors of order $m \ge 3$ has been motivated by applications in blind source separation, magnetic resonance imaging, molecular conformation, and more. In this paper, we consider methods for computing real symmetric-tensor eigenpairs of the form $\boldsymbol{\mathscr{A}}\mathbf{x}^{m-1} = \lambda \mathbf{x}$ subject to $\|\mathbf{x}\|=1$, which is closely related to optimal rank-1 approximation of a symmetric tensor. Our contribution is a shifted symmetric higher-order power method (SS-HOPM), which we show is guaranteed to converge to a tensor eigenpair. SS-HOPM can be viewed as a generalization of the power iteration method for matrices or of the symmetric higher-order power method. Additionally, using fixed point analysis, we can characterize exactly which eigenpairs can and cannot be found by the method. Numerical examples are presented, including examples from an extension of the method to finding complex eigenpairs.

Design and implementation of reduced-order sliding mode controller for higher-order power factor correction converters

This study discusses a simple sliding surface design approach of a reduced-order sliding mode controller (ROSMC) for power factor correction, wherein a new and systematic technique for the selection of sliding surface co-efficients to implement ROSMC is attempted. Pade's approximation technique is used to obtain the reduced-order model. A prototype of front-end AC–DC converter followed by DC–DC Cuk converter controlled by ROSMC using a dSPACE signal processor is set up for 60 W. Experimental results are presented to validate the simulation results. Simulation and experimental results reveal that ROSMC control can achieve good output voltage regulation and also provide improved robustness in shaping the input current in the presence of load variations.

Shadow Map Anti-aliasing Algorithm with High-order Power Function Approximation

Shadow Map Anti-aliasing Algorithm with High-order Power Function Approximation

Finite-size effects for the gap in the excitation spectrum of the one-dimensional Hubbard model

We study finite-size effects for the gap of the quasiparticle excitation spectrum in the weakly interacting regime one-dimensional Hubbard model with on-site attraction. Two types of corrections to the result of the thermodynamic limit are obtained. Aside from a power law (conformal) correction due to gapless excitations which behaves as $1/{N}_{a}$, where ${N}_{a}$ is the number of lattice sites, we obtain corrections related to the existence of gapped excitations. First of all, there is an exponential correction which in the weakly interacting regime ($|U|\ensuremath{\ll}t$) behaves as $~$$\mathrm{exp}(\ensuremath{-}{N}_{a}{\ensuremath{\Delta}}_{\ensuremath{\infty}}/4t)$ in the extreme limit of ${N}_{a}{\ensuremath{\Delta}}_{\ensuremath{\infty}}/t\ensuremath{\gg}1$, where $t$ is the hopping amplitude, $U$ is the on-site energy, and ${\ensuremath{\Delta}}_{\ensuremath{\infty}}$ is the gap in the thermodynamic limit. Second, in a finite-size system a spin-flip producing unpaired fermions leads to the appearance of solitons with nonzero momenta, which provides an extra (nonexponential) contribution $\ensuremath{\delta}$. For moderate but still large values of ${N}_{a}{\ensuremath{\Delta}}_{\ensuremath{\infty}}/t$, these corrections significantly increase and may become comparable with the $1/{N}_{a}$ conformal correction. Moreover, in the case of weak interactions where ${\ensuremath{\Delta}}_{\ensuremath{\infty}}\ensuremath{\ll}t$, the exponential correction exceeds higher-order power law corrections in a wide range of parameters, namely for ${N}_{a}\ensuremath{\lesssim}(8t/{\ensuremath{\Delta}}_{\ensuremath{\infty}})\mathrm{ln}(4t/|U|)$, and so does $\ensuremath{\delta}$ even in a wider range of ${N}_{a}$. For a sufficiently small number of particles, which can be of the order of thousands in the weakly interacting regime, the gap is fully dominated by finite-size effects.

転写率，遺伝係数による板断面<br>プロフィル推定モデルの高精度化

Sectional thickness profile control is one of the important size control demands for highly accurate flat products. Profile prediction is necessary for setting up profile control devices in flat rolling mills. The profile prediction of flat products is performed by analyses using complicated models and FEM models. These analyses need a long elapse time even with the fastest computers, and are difficult to apply in actual mill operations. To solve such problems, an equation involving the transcription ratio of the roll profile and the inheritance ratio of the inlet profile is used. To obtain a highly accurate prediction, consistent ratios and other factors are needed for the equation. There are only a few studies of this equation in which such ratios are numerically discussed, especially with regard to prediction accuracy. In this paper, the accuracy of the profile prediction equation is discussed using a simple quasi-three dimensional rolling model that we developed. It is clear that the mechanical crown of the profile prediction equation must be defined anew, and that a combination of a quadratic curve and a high-order power curve is necessary for such an equation.

Effects of phonon dimensionality in the specific heat of multiwall carbon nanotubes at low temperatures

We have measured the specific heat at constant pressure, Cp, of three different samples of multiwall carbon nanotubes (MWNT). For all samples, Cp departs from a graphitic behavior at T < 120 K. Cp measurements show a temperature threshold from a linear regime for intermediate temperature to a higher-order power law for low temperatures. Moreover, it was found that this crossover only depends on the internal structure of the individual MWNT and not on the spatial order of the MWNT within a bundle.

An analytical solution of the stiffness equation for linear guideway type recirculating rollers with arbitrarily crowned profiles

This article derives the stiffness equation for linear guideway type (LGT) recirculating rollers with arbitrarily crowned profiles. Recirculating rollers compressed between a carriage and a profile rail are simulated as rollers compressed between two plates, and each roller is divided into three parts: two crowned and one cylindrical. The superposition method is introduced to obtain the stiffness equation for a crowned roller, for which rollers with circular, quadratic, cubic, fourth-order power, and exponential profiles were analysed. A model of discrete normal springs is used to obtain the stiffness equation for LGT recirculating rollers. The results reveal that a higher-order power can make an LGT with higher stiffness. The stiffness of the exponential profile is close to that of the fourth power profile. Therefore, recirculating rollers with an exponential profile, a small crowned depth, and a large crowned length seem to be optimal, obtaining a higher LGT stiffness and a lower edge stress concentration.

Nonlinear calculating method of pile settlement

To study calculating method of settlement on top of extra-long large-diameter pile, the relevant research results were summarized. The hyperbola model, a nonlinear load transfer function, was introduced to establish the basic differential equation with load transfer method. Assumed that the displacement of pile shaft was the high order power series of buried depth, through merging the same orthometric items and arranging the relevant coefficients, the solution which could take the nonlinear pile-soil interaction and stratum properties of soil into account was solved by power series. On the basis of the solution, by determining the load transfer depth with criterion of settlement on pile tip, the method by making boundary conditions compatible was advised to solve the load— settlement curve of pile. The relevant flow chart and mathematic expressions of boundary conditions were also listed. Lastly, the load transfer methods based on both two-broken-line model and hyperbola model were applied to analyzing a real project. The related coefficients of fitting curves by hyperbola were not less than 0.96, which shows that the hyperbola model is truthfulness, and is propitious to avoid personal error. The calculating value of load—settlement curve agrees well with the measured one, which indicates that it can be applied in engineering practice and making the theory that limits the design bearing capacity by settlement on pile top comes true.

Designing the coordinate transformation function for non-magnetic invisibility cloaking

An optical invisibility cloak based on a transformation approach has recently been proposed by a reduced set of material properties due to their easier implementation in reality and little need for an inhomogeneous permeability distribution, but the drawback of undesired scattering caused by the impedance mismatching at the outer boundary is unavoidable in such a cloak. By properly designing the coordinate transformation function to ensure impedance matching at the outer surface, we show that the performance of a nonmagnetic cylindrical cloak could be improved with minimized scattering fields. Using either a single high order power function or an optimized piecewise continuous power function, a cylindrical non-magnetic cloak has been designed with nearly perfect cloaking performance, which is better than those generated with a linear or a quadratic function. Due to the monotonicity of the designed power functions, the resulting cloak has no restriction on the size of the cloaking shell, therefore is suitable for both thick and thin cloaking structures.