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About 3,539 papers for “Nested set model”

Learning to Construct Nested Polar Codes: An Attention-Based Set-to-Element Model

Yang Li, Zhitang Chen, Guochen Liu et al. · IEEE Communications Letters · 2021

As capacity-achieving codes under successive cancellation (SC) decoding, nested polar codes have been adopted in 5G enhanced mobile broadband. To optimize the performance of the code construction under practical decoding, e.g. SC list (SCL) decoding, artificial intelligence based methods have been explored in the literature. However, the structure of nested polar codes has not been fully exploited for code construction. To address this issue, this letter transforms the original combinatorial optimization problem for the construction of nested polar codes into a policy optimization problem for sequential decision, and proposes an attention-based set-to-element model, which incorporates the nested structure into the policy design. Based on the proposed architecture for the policy, a gradient based algorithm for code construction and a divide-and-conquer strategy for parallel implementation are further developed. Simulation results demonstrate that the proposed construction outperforms the state-of-the-art nested polar codes for SCL decoding.

Cited by 18

An Improved Finite Control-Set Model Predictive Control for Nested Neutral Point Clamped Converter

Kourosh Khalaj Monfared, Yousef Neyshabouri, Hossein Iman‐Eini et al. · IEEE Transactions on Industrial Electronics · 2022

This article presents an improved model predictive control with a finite control set (IFCS-MPC) for a four-level nested neutral point clamped (4L-NNPC) inverter. Controlling flying capacitors (FCs) voltages of 4L-NNPC, especially at low output frequency, is a challenging issue. In the proposed method, the control objectives of 4L-NNPC (current, FCs voltages, and switching losses of power devices) are formulated in terms of model predictive control with finite control set (FCS-MPC). Furthermore, a computational burden reduction technique is introduced that reduces the search space from 216 to 96 switching states for a three-phase system. In addition to the current control, the proposed control method has the ability to control FCs voltages in the entire operating frequency range and also decreases the switching losses of the converter in comparison to the alternative methods. Also, it offers a lower computational burden than conventional FCS-MPC, which is of importance in implementation of MPC. The performance of the suggested method is verified on a 4L-NNPC in MATLAB/SIMULINK. Also, the experimental results are carried out based on a scaled-down hardware prototype validating the theoretical claims.

Cited by 15

Finite Control-Set Model Predictive Control (FCS-MPC) of Nested Neutral Point-Clamped (NNPC) Converter

Mehdi Narimani, Bin Wu, Venkata Yaramasu et al. · IEEE Transactions on Power Electronics · 2015

This paper proposes a model predictive control (MPC) strategy for a nested neutral point-clamped (NNPC) converter to control output currents and voltages of flying capacitors. The NNPC converter is a four-level converter topology for medium-voltage applications with interesting properties such as operating over a wide range of voltages (2.4–7.2 KV) without the need for connecting power semiconductor in series, high quality output voltage, less number of components compared to other classical four-level topologies. A discrete-time model of the converter is presented and all the control objectives are formulated in terms of the switching states. During each sampling interval, the predicted variables are assessed by the cost function and the best switching state which gives minimum value for the cost function is selected and applied to the converter gating terminals. The performances of the NNPC converter and predictive control scheme are verified through MATLAB/Simulink simulations and their feasibility is evaluated experimentally.

Cited by 159

Summary of model fitting results for the nested set of factors and four different families of distributions.

Frederick Feyrer (430927), Donald Portz (430928), Darren Odum (430929) et al. · Figshare · 2015

<p>H+V+T is main effects only, H:V+H:T+V:T is main effects and 2-way interactions, and H*V*T is main effects, 2-way and 3-way interactions. Po = Poisson, Q-Po = Quasi-Poisson, NB = Negative Binomial, ZINB = Zero Inflated Negative Binomial. The Var entries refer to the variance function for the distribution families. The Signif entries denote the significant factor effects, with superscripts ‘,*, and ** denoting significance at the 0.10, 0.05, and 0.01 levels, respectively. The reported AIC value for the Q-Po case is the Quasi-AIC value.</p>

Cited by 0Open access

Fast finite control set model predictive control for three-phase five-level nested neutral point piloted converter

Junjie Li, Dan Zhang, Jianguo Jiang · IECON 2017 - 43rd Annual Conference of the IEEE Industrial Electronics Society · 2017

Conventional finite control set model predictive control (FCS-MPC) for multilevel converters can realize multi-objective control and contain the nonlinear characteristics. However, conventional FCS-MPC may lead to high computational complexity and unwanted switching transition, which is not easy to implement. To solve the issues of computational burden and unwanted switching transition, this paper proposes the fast FCS-MPC for three-phase five-level nested neutral point piloted (NNPP) converter. According to the switching principle, the finite control subset of the effective candidates is obtained from all of the switching combinations, which significantly reduces the necessary iterations and computational complexity. The proposed fast FCS-MPC also avoids output level jump and unwanted switching transition. Moreover, the neutral-point voltage balance and reducing switching frequency are also taken into account in the cost function. Finally, the five-level NNPP converter simulation model is built. The simulation results verify the correctness of the proposed fast FCS-MPC.

Cited by 4

Simplified Finite-Set Model Predictive Control for Full-Frequency Operation of Five-Level Nested Neutral-Point-Clamped Inverters

Qingle Sun, Zifan Lin, Zhifu Wang et al. · IEEE Transactions on Power Electronics · 2024

This article proposes a simplified finite-set model predictive control (FS-MPC) algorithm for full-frequency operation of five-level nested neutral-point-clamped (5L-NNPC) inverters. Compared to the existing FS-MPC of 5L-NNPC inverters, the proposed algorithm substantially reduces the computational burden and simplifies the tuning of the weighting factor while ensuring low current harmonics and full-frequency capacitor voltage balance. The full-frequency operating conditions that the candidate sets should satisfy are first acquired considering the periodic characteristics of the capacitor voltages. On this basis, a computationally efficient varying candidate set selection method is proposed for high-frequency operation, while a simple compensation set is introduced for low-frequency operation. Besides, an online approach is proposed to calculate available switching states for different candidate sets, eliminating tedious offline preprocessing. Furthermore, a staged cost function evaluation method is presented to further simplify the computation. Experimental results validate the proposed algorithm.

Cited by 6

Evaluation of United Arab Emirates WRF two-way nested model on a set of thick coastal fog situations

Ajjaji Radi, Ahmad Awad Al-katheri, Khaled Al-chergui · 2015

United Arab Emirates (U.A.E.) is suffering almost all the year by the consequences of visibility reduction caused either by persistent dust and haze episodes or by the occurrence of thick fogs especially over marine and costal regions. Visibility drop due to fog usually happens during late night and early morning and could last several hours before dissipation. The U.A.E coastal fogs are generally advective caused by the north westerly surface flow draining huge amounts of moisture from the Arabian Gulf sea strait to the 600 km U.A.E western and southern coasts. The large contrast in temperature between land and sea especially during winter season accelerates the condensation process over land near the surface, and contributes to the formation of low stratiform clouds close to the surface since the very beginning of night time. The Weather Research and Forecasting model is among the tools used by the forecasters for fog prediction. It offers a large number of prognostic and diagnostic fog predictability parameters. However, UAE WRF is not always successful in predicting fog formation. Recently, during February and March 2008, among more than 10 thick fog situations, only 6 were correctly predicted. This study aims the scientific evaluation of multiple WRF fog ingredients like physical parameterizations schemes (microphysics, radiation, planetary boundary layer, surface, horizontal diffusion), horizontal and vertical resolution, assimilation techniques (3D-Var, Nudging), over a series of 2008 winter and spring fog situations. It has been found that the inner most nest with very fine resolution (1.4km), an adapted microphysics scheme (Lin et al.), an adequate planetary boundary scheme (Yonsei University)

Cited by 7

Control of Induction Motor Drive based on Nested Neutral Point Clamped Inverter using Finite Control-Set Model Predictive Method

Kourosh Khalaj Monfared, Hossein Iman-Eini, Yousef Neyshabouri · SHILAP Revista de lepidopterología · 2023

This paper presents a finite control set model predictive control for a four-level nested neutral point clamped converter (4L-NNPC) in electric drive application. Controlling the voltage of the flying capacitors (FCs) in this converter, especially at low output frequency, is challenging due to the lack of complete switching states to control the FCs voltages. In the proposed method, the main control objectives of the electrical motor and converter, i.e., the control of the torque, flux, and voltage of the FCs, have been formulated. A modified weighting factor for FC voltage objective in the cost function is introduced, which provides the full possibility of controlling voltage fluctuations of FCs, especially in low-frequency operation. The proposed control method, in addition to controlling the electric motor's required objectives, can control the voltage of the FCs of the converter in the entire operating frequency range. The performance of the proposed method has been simulated and verified on a 4L-NNPC converter using a 1500 HP, 4160 V electric drive in the MATLAB/Simulink software environment.

Cited by 0Open access

An Improved Finite Control Set Model Predictive Control with Complete Control of Flying-Capacitor Voltages for Four-Level Nested Neutral-Point Clamped Inverters

Yahui Zhang, Hua Chen, Chang Liu et al. · 2024

This article introduces an enhanced FCS-MPC technique that allows for full control of flying capacitor (FC) voltages in a four-level inverter. This method reduces the computational burden, decreases harmonic currents, and ensures balanced FC voltage levels. Firstly, the vector in the a-b-c coordinate system is converted to the g-h coordinate system. Then determine the region where the reference voltage vector is located, and the four-level vectors are converted into a two-level sector for calculation. Next, the influence of the switching state corresponding to the redundancy vector on the FC is analyzed, and the switching states which makes the FC voltage balance are selected. Finally, the duty cycle of the three basic voltage vectors is computed by the distance between the reference vector and the fixed vectors in the space vector diagram. The steady-state and the dynamic simulations are conducted to verify the effectiveness of the proposed FCS-MPC method.

Cited by 0

NestedCategBayesImpute: Modeling, Imputing and Generating Synthetic Versions of Nested Categorical Data in the Presence of Impossible Combinations

Quanli Wang, Olanrewaju Akande, Jingchen Hu, Jerry Reiter and Andres Barrientos · 2016

This tool set provides a set of functions to fit the nested Dirichlet process mixture of products of multinomial distributions (NDPMPM) model for nested categorical household data in the presence of impossible combinations. It has direct applications in imputing missing values for and generating synthetic versions of nested household data.

Cited by 1

Estimation with the Nested Logit Model

Silberhorn, Nadja, Boztuğ, Yasemin, Hildebrandt, Lutz · edoc Publication server (Humboldt University of Berlin) · 2007

Estimation with the Nested Logit Model: Specifications and Software Particularities Abstract: The paper discusses the nested logit model for choices between a set of mutually exclusive alternatives (e.g. brand choice, strategy decisions, modes of transportation, etc.). Due to the ability of the nested logit model to allow and account for similarities between pairs of alternatives, the model has become very popular for the empirical analysis of choice decisions. However the fact that there are two different specifications of the nested logit model (with different outcomes) has not received adequate attention. The utility maximization nested logit (UMNL) model and the non-normalized nested logit (NNNL) model have different properties, influencing the estimation results in a different manner. This paper introduces distinct specifications of the nested logit model and indicates particularities arising from model estimation. The effects of using various software packages on the estimation results of a nested logit model are shown using simulated data sets for an artificial decision situation.

Cited by 0Open access

Efficiency evaluation for the nested cube response surface design

Melvin Gail Linnell · Montana State University ScholarWorks (Montana State University) · 2015

The nested cube response surface design is defined and its attributes described.Variance, bias and potential estimators are evaluated for the nested cube design.The standard least-squares estimator is examined for the quadratic and cubic models.Estimable parameters in the cubic model are derived for the nested cube design as well as a set of select designs.A minimum bias estimator is examined where the true model is cubic and the fitted model is quadratic.The nested cube design was the only design of the set examined for which the estimator existed.Two measures of bias efficiency are introduced and used to compare the nested cube design to a set of selected designs.Variance efficiency is evaluated in terms of A-, V-, and D-efficiencies.A calculation formula for the determinant of the sum of squares matrix is derived for symetric designs with zero odd moments.Profiles of the variance are shown on selected vectors in the region of interest........

Cited by 0Open access

G.: Access and Exchange of Hierarchically Structured Resources on the Web with the NESTOR Framework

Maristella Agosti, Nicola Ferro, Gianmaria Silvello · 2009

Abstract—The paper addresses the problem of representing, managing and exchanging hierarchically structured data in the context of Digital Library (DL) systems in order to enhance the access and exchange DL resources on the Web. We propose the NEsted SeTs for Object hieRarchies (NESTOR) framework, which relies on two set data models — the “Nested Set Model (NS-M) ” and the “Inverse Nested Set Model (INS-M) ” — to enable the representation of hier-archical data structures by means of a proper organization of nested sets. In particular, we show how NESTOR can be effectively exploited to enhance Open Archives Initiative Protocol for Metadata Harvesting (OAI-PMH) for better access and exchange of hierarchical resources on the Web. Keywords-hierarchical structures; set data models; OAI-PMH; data access and exchange I.

Cited by 0

Microsatellite diversity and broad scale geographic structure in a model legume: building a set of nested core collection for studying naturally occurring variation in -2

Ronfort, Joëlle, Bataillon, Thomas, Santoni, Sylvain et al. · Figshare · 2011

<b>Copyright information:</b>Taken from "Microsatellite diversity and broad scale geographic structure in a model legume: building a set of nested core collection for studying naturally occurring variation in "BMC Plant Biology 2006;6():28-28.Published online 13 Dec 2006PMCID:PMC1762007.strategy (grey) are compared for various Core (collection) sizes. For each core size, the score of each method reported here is an average over a hundred independent core collections. The score of the set nested core collections retained to represent the diversity of our collection (CC8 to CC96) are represented by grey circles.

Cited by 0Open access

Microsatellite diversity and broad scale geographic structure in a model legume: building a set of nested core collection for studying naturally occurring variation in -2

Ronfort, Joëlle, Bataillon, Thomas, Santoni, Sylvain et al. · Figshare · 2011

<b>Copyright information:</b>Taken from "Microsatellite diversity and broad scale geographic structure in a model legume: building a set of nested core collection for studying naturally occurring variation in "BMC Plant Biology 2006;6():28-28.Published online 13 Dec 2006PMCID:PMC1762007.strategy (grey) are compared for various Core (collection) sizes. For each core size, the score of each method reported here is an average over a hundred independent core collections. The score of the set nested core collections retained to represent the diversity of our collection (CC8 to CC96) are represented by grey circles.

Cited by 0Open access