Iterative Design Method Research Articles

Wide angle 2D beam splitter design based on vector diffraction theory

DOE with wide diffraction angle requires the feature size down to subwavelength. However, the emerging vectorial effect of light beam makes the scalar diffraction theory invalid. To address this problem, a hybrid iterative design method is proposed for 2D beam splitter in this work. Firstly, several initial solutions are obtained by non-paraxial scalar iterative Fourier transform algorithm (IFTA). Then, rigorous coupled wave analysis (RCWA) is used as evaluation function to compute the diffraction efficiency and uniformity. Combined with the Genetic Algorithm, the second optimization of DOE is implemented to obtain the final optimal surface relief structure. Numerical simulations and optical experiments are both performed to verify the proposed algorithm. The results obtained by the experiments and the simulation results are compared, and the relevance between the two results are above 80%. This work can open a new way for the 2D DOE design with wide diffraction angle.

An Iterative Method of the Structural-Parametric Design of Robust Systems with State Controllers

An iterative method for designing a robust control system with state controllers is proposed that includes a transformation of the plant structure to improve its controllability by correcting the singular values of the controllability Gramian and the subsequent synthesis of the basic controller for the corrected plant using modal control. This approach allows us to design systems satisfying the robust stability condition for the given intervals of variation of the plant parameters.

Computational Investigation of a Boundary-Layer-Ingestion Propulsion System

The present paper examines the potential propulsive and aerodynamic benefits of integrating a boundary-layer ingestion propulsion system into the Common Research Model geometry and the NASA tetrahedral unstructured software system. The numerical propulsion system simulation environment is used to generate engine conditions for computational fluid dynamics analyses. Improvements to the boundary-layer ingestion geometry are made using the constrained direct iterative surface curvature design method. The potential benefits of the boundary-layer ingestion system relating to cruise propulsive power are quantified using a power balance method, and a comparison to the baseline case is made. Iterations of the boundary-layer ingestion geometric design are shown, and improvements between subsequent boundary-layer ingestion designs are presented. Simulations are conducted for a cruise flight condition of Mach 0.85 at an altitude of 38,500 ft, with a Reynolds number of 40 million based on the mean aerodynamic chord and an angle of attack of 2 deg for all geometries. The results indicate an 8% reduction in engine power requirements at cruise for the boundary-layer ingestion configuration as compared to the baseline geometry. Small geometric alterations of the aft portion of the fuselage using constrained direct iterative surface curvature are shown to marginally increase the benefit from boundary-layer ingestion further, resulting in an 8.7% reduction in power requirements for cruise, as well as a drag reduction of approximately 12 counts over the baseline geometry.

Iterative Innovation Design Methods for Internet Products in the Era of Big Data

This paper aims to elaborate on the iterative innovation design methods of Internet products in the era of big data. Through the analysis of current Internet product iteration design practice, we examine the impact of big data thinking on Internet product design in terms of design scope, design concepts, and design methods, and we propose iterative innovation design methods relating to targeted advertising delivery, customizing users’ potential demands, and dynamic optimization of marketing promotion strategy. Finally, we discuss the advantages and precautions of using big data thinking on Internet product iterative design, proposing the appropriate advice for the development of the Internet product design.

효과적인 감정 분류를 위한 반복적 나이브 베이지안 분류기 설계

가우시안 나이브 베이지안 분류기는 지도 학습(Supervised Learninig)방법 중의 하나로 데이터의 분포를 가우시안으로 가정하고 베이즈룰을 이용하여 데이터를 분류한다. 이러한 가우시안 나이브 베이지안 분류기는 주로 사람의 감정 상태를 분류, 판단하는 연구에서 사용된다. 본 논문에서는 가우시안 나이브 베이지안 분류기에 반복 알고리즘을 적용시켜 더욱 효과적인 분류기 설계 방법을 제안한다. 기존의 방법의 경우 훈련 데이터(Training data)를 이용하여 고정된 분류기를 설계하고, 이 분류기를 검증 집합(Validation data)을 이용하여 평가하였다. 하지만 고정된 분류기는 감정과 같이 개개인의 차이로 인해 생기는 산발적인 데이터를 분류할 때 문제점이 발생하며 딥러닝이나 AI 분야에 적용하기 어렵다. 따라서 본 논문에서 기존의 가우시안 나이브 베이지안 분류기에 반복 알고리즘을 적용하여 이를 보안한다. 제안하는 방법에서는 검증 집합을 이용하여 평가할 때, 실제론 그 부류에 속하는 데이터이지만 오분류된 데이터를 기억한다. 오분류 데이터 개수가 일정 수준이 넘어가면 이를 기존의 훈련 집합에 포함하여 분류기를 재설계한다. 본 논문에서 제안하는 분류기의 성능을 평가하기 위해 DEAP 데이터 중 EEG 신호를 이용하였으며, 검증 결과 기존보다 정확도 높은 분류기를 얻을 수 있었다.

New design method for multi‐stack disc‐type hysteresis motors based on analytical calculations

Hysteresis motors are widely employed for a variety of high speed applications, thanks to their unique features. Usual design methods could not be used for these motors since the operation mechanism of hysteresis motors is also unique. However, an appropriately developed design method has not been provided by the few relevant published works. This study presents a new iterative design method, which is capable of being used for almost all hysteresis motor structures. Also, it is almost independent of the approach of obtaining the design equations. Multi-stack disc-type slotless structure has been selected as the case study, because of its interesting capabilities. Its design equations are derived by combining the fundamental laws of electromagnetism with the elliptical model of hysteresis loops. Some new techniques are introduced to increase the accuracy of these equations. A sample motor has been designed by applying the direct search optimisation to the proposed design method. The prototyped sample motor has been subjected to various tests. The measured operating characteristics show a great agreement with the design requirements.

Medical therapy and imaging fixed-field alternating-gradient accelerator with realistic magnets

NORMA is a design for a normal-conducting race track fixed-field alternating-gradient accelerator (FFAG) for protons from 50 to 350 MeV. In this article we show the development from an idealised lattice to a design implemented with field maps from rigorous two-dimensional (2D) and three-dimensional (3D) FEM magnet modelling. We show that whilst the fields from a 2D model may reproduce the idealised field to a close approximation, adjustments must be made to the lattice to account for differences brought about by the 3D model and fringe fields and full 3D models. Implementing these lattice corrections we recover the required properties of small tune shift with energy and a sufficiently-large dynamic aperture. The main result is an iterative design method to produce the first realistic design for a proton therapy accelerator that can rapidly deliver protons for both treatment and for imaging at up to 350 MeV. The first iteration is performed explicitly and described in detail in the text.

Optimization of a Construction of the Milling Combine on the Basis of a Moon Rover by Means of Technology of Imitating Dynamic Modeling

The work presents the comparative analysis of the options of a design of the milling combine created on the basis of a moon rover by means of imitating calculations. The work is focused on the section "The federal space program of Russia for 2016-2025 - "Basic space researches" according to which the problem of creation of the milling combine for carrying out geological researches on a surface of other planets is actual. The research objective is optimization of a design of the milling combine created on the basis of a moon rover by means of technology of ultrahigh and polygonal dynamic 3D modeling. For achievement of a goal the technological chain which is conditionally divided into some main stages was used. Due to the insistence to resources and specifics of tasks imitating modeling was carried out by means of hardware-software complexes. Results in the form of models of the milling combine and a lunar surface are received. The interactive simulator functioning in modern full-scale technologies of virtual reality for training of future operators when performing missions to the Moon is created. The design shape conforming to requirements received by an iterative method of design can be applied in systems of information support at all stages of life cycle of a product. Carrying out such works is a necessary condition of providing prospects of use of systems of modeling, both for carrying out examinations, and in interests of the solution of perspective tasks of designing of space equipment.

An Iterative Method for Control Gain Design of Multiagent Systems With Process Noise

This brief aims to optimize the consensus performance of multiple homogeneous agents, each of which is governed by a general discrete-time linear system with white process noise, exchange state information with its neighboring agents according to an undirected communication topology, and generates its local control in a linear way. The common control gain of agents determines the consensus performance, which is measured by the ultimate mean square deviation of the states of agents. The consensus performance optimization with respect to the control gain takes a nonlinear matrix inequality form and is difficult to solve. To handle this nonlinearity issue, this brief proposes an iterative method. At each iteration, a descent direction of the control gain is computed by solving two linear matrix inequality optimizations based on a given feasible control gain. Then, a line search algorithm is implemented to move the control gain along the obtained descent direction to improve the consensus performance. That updated control gain will work as the starting feasible control gain of the next iteration. This method can well handle the nonlinearity of the original consensus performance optimization and efficiently improve the consensus performance, which is confirmed by simulations.

Iterative method for the design of LP0m mode converter

An iterative method based on coupled mode theory and the steepest descent principle in a microwave waveguide is proposed in the optical waveguide for the design of a LP0m mode converter. After iterative design, a LP02-LP01 mode converter and a LP03-LP02 mode converter can achieve 99% conversion efficiency in our model. The 1dB bandwidth of a LP02-LP01 mode converter is measured as more than 130 nm. These optimum waveguides are simulated by RSoft software and indicate high conversion efficiency as well. Furthermore, we investigate the compatibility of the iterative method for mode converter design with initial waveguides of multiple taper shapes. The proposed method is promising for applications in mode division multiplexing systems.

Networked control design for coalitional schemes using game-theoretic methods

In this work, we present an iterative design method for a coalitional networked control scheme for linear systems. In this scheme, the links in the communication network are enabled or disabled depending on their contribution to the overall system performance. Likewise, the control law is adapted to these changes. In particular, new conditions are included at the design phase, in order to consider constraints on the links and the agents regarding the game theoretical tools utilized while optimizing the matrices that define the controller.

Alternative Multiplicative Iterative Method for Projection Matrix Design in Compressive Images

Projection matrix plays an important role in compressive sensing (CS). Small mutual coherence between a projection matrix and a sparsifying matrix is considered to enhance reconstruction performance in CS. The equiangular tight frame (ETF) was demonstrated with minimum mutual coherence in previous works. However, ETF does not exist for any dimensions. A practical solution is to make the production of a projection matrix and a sparsifying matrix become the nearest one to ETF. Here, the optimization objective is regarded as the minimization of error between them. First, a maximum-likelihood estimation model is presented to crack the minimization problem. Then an alternative multiplicative iteration method is employed to guarantee that the error will converge to the minimum efficiently. Experimental results show that the proposed method obtains smaller mutual coherence with better reconstruction performance compared to existing methods.

A superconducting manifold‐coupled triplexer with an iterative design method at X‐band

ABSTRACTThis paper presents a superconducting manifold‐coupled narrowband triplexer at X‐band frequency. The high Q‐value resonator is adopted to create a filter with low insertion loss. Impedance matching and iterative design methods are used to design the duplexer and manifold structure. Furthermore, metal shielding plates are used to separate the three channels to suppress the box resonant modes. The three bandwidths of the superconducting triplexer are all 60 MHz, and the center frequencies are 9.0, 9.12, and 9.24 GHz. The triplexer exhibits good performance at 65 K, with an insertion loss of 0.7 dB at 9.24 GHz. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:2949–2954, 2016

Iterative Beamformer Design for Multi-Node MIMO Two-Way Relay Networks Using Duality

In this paper, an iterative design method for beamformers is proposed for multiple-input multiple-output (MIMO) two-way relay networks with multiple pairs of source nodes. It is known that the joint beamformer design problem based on the minimum mean-square-error (MMSE) is known to be nonconvex, and it cannot be analytically solved. To manage this difficulty, a novel iterative algorithm is proposed, which uses duality relationships. First, the MSE duality for MIMO two-way relay networks with multiple pairs of nodes is presented. Moreover, the optimization problem is divided into three subproblems, which can be separately solved; then, the duality is applied to the proposed iterative algorithm, which provides closed-form solutions for all subproblems. The numerical results demonstrate that the proposed method improves network performance and can be applied to various communication systems that use the two-way relay network.

Ultra-high strength concrete made with recycled aggregate from sanitary ceramic wastes – The method of production and the interfacial transition zone

The article describes a new model of ultra-high strength concrete (UHSC) production. It was assumed that the components will be generally available in the concrete plant such as cement, plasticizing admixtures and pozzolanic additives. Aggregate used will be a post-production sanitary ceramic wastes, selected to the two fractions of 0–4mm and 4–8mm. The goal of this study was to produce concrete with the highest strength parameters using iterative design method of concrete mix. For so obtained concrete, its basic physical and mechanical parameters were examined, such as: compressive and tensile strength, bulk density, water absorption, water permeability and frost resistance. The examined parameters were compared with results obtained on the reference samples made with the same ingredients, only used aggregate was gravel (0–4mm) and basalt (4–8mm). In addition, the interfacial transition zone (ITZ) between cement paste and aggregate (ceramic and basalt) was analyzed, using Scanning Electron Microscope (SEM). On this basis, conclusions on the impact of the ITZ’s microstructure on the final characteristics of concrete were made. Own model of cement paste adhesion to the ceramic wastes aggregate was developed.

Evaluation of Variable Density and Data-Driven K-Space Undersampling for Compressed Sensing Magnetic Resonance Imaging.

The aim of this study was to investigate the influence of variable density and data-driven k-space undersampling patterns on reconstruction quality for compressed sensing (CS) magnetic resonance imaging to provide recommendations on how to avoid suboptimal CS reconstructions. First, we investigated the influence of randomness and sampling density on the reconstruction quality when using random variable density and variable density Poisson disk undersampling. Compressed sensing reconstructions on 1 knee and 2 brain data sets were compared with fully sampled data sets and reconstruction errors were measured. Sampling coherence was evaluated on the undersampling patterns to investigate whether there was a relation between this coherence measure and reconstruction error.Second, we investigated whether data-driven undersampling methods could improve reconstruction quality when 1 or more fully sampled scans are available as a training set. We implemented 3 different data-driven undersampling methods: (1) Monte Carlo optimization of variable density and variable density Poisson disk undersampling, (2) calculating sampling probabilities directly from the k-space power spectra of the training data, and (3) iterative design of undersampling patterns based on CS reconstruction errors in k-space.Two cross-validation experiments were set up using retrospective undersampling to evaluate the 3 data-driven methods and the influence of the size of the training set. Furthermore, in an experiment that included prospective under sampling, we show the practical applicability of 2 of the data-driven methods. Compressed sensing reconstruction quality was measured with both the normalized root-mean-square error metric and the mean structural similarity index measure. Different optimal variable sampling densities were found for each of the data sets, showing that the optimal sampling density is data dependent. Choosing a sampling density other than the optimal density decreased reconstruction quality. These results suggest that choosing a sampling density without having any reference scans is likely suboptimal. Furthermore, no meaningful correlation was found between sampling coherence and reconstruction error.For the data-driven methods, the iterative method yielded statistically significantly higher reconstruction quality in both retrospective and prospective experiments. In retrospective experiments, the power spectrum method yielded a reconstruction quality that was comparable with the data-driven variable density method. The size of the training set had only a minor influence on the reconstruction quality. Data-driven undersampling methods can be used to avoid suboptimal reconstruction quality in CS magnetic resonance imaging, provided that at least 1 fully sampled scan is available to train the data-driven method. The iterative design method resulted in the highest reconstruction quality.

Technology combined with a counseling protocol to stimulate physical activity of chronically ill patients in primary care.

An iterative user-centered design method was used to develop and test mobile technology (the It's LiFe! tool/monitor) embedded in primary care, followed by a three months feasibility study with 20 patients and three nurses. The tool consists of an accelerometer that transfers data to an app on a Smartphone, which is subsequently connected to a server. Physical activity levels are measured in minutes per day compared to pre-set activity goals, which are set by patients in dialogue with nurses. Nurses can monitor patients' physical activity via a secured website. The counseling protocol is based on the Five A's model and consists of a limited number of behavior change consultations intertwined with interaction with and responses from the tool. The technology supports nurses when performing physical activity counseling. Provided that no connectivity problems occur, the It's LiFe! intervention is feasible, and its longitudinal effects will be tested in a cluster RCT.

An Iterative Learning Control Design Method for Nonlinear Discrete-Time Systems with Unknown Iteration-Varying Parameters and Control Direction

An iterative learning control (ILC) scheme is designed for a class of nonlinear discrete-time dynamical systems with unknown iteration-varying parameters and control direction. The iteration-varying parameters are described by a high-order internal model (HOIM) such that the unknown parameters in the current iteration are a linear combination of the counterparts in the previous certain iterations. Under the framework of ILC, the learning convergence condition is derived through rigorous analysis. It is shown that the adaptive ILC law can achieve perfect tracking of system state in presence of iteration-varying parameters and unknown control direction. The effectiveness of the proposed control scheme is verified by simulations.

Analysis and Parameter Optimization of Start-Up Process for <italic>LLC</italic> Resonant Converter

There is a current spike in LLC resonant converter during start-up and frequency modulation method is adopted to limit the resonant current usually, which controls switching frequency decreasing from specific high frequency to steady-state frequency in exponential pattern with a time constant tau. However, it is hard to determine the crucial parameter of time constant of the exponential switching frequency sweep curve, due to the complexity in analyzing dynamic process of the converter. In this paper, the operation modes and characteristics under continued conductive mode and discontinued conductive mode are analyzed based on state-plane analysis and the boundary of two conductive modes is figured out. Then, the iteration calculation model of the LLC converter is proposed to predict the resonant current during start-up progress, and time constant of the existing soft start method is optimized using iteration algorithm. Using the proposed iterative design method, the current stress of LLC resonant converter is limited, as well as guaranteeing the response speed of output voltage.

Design of near-perfect-reconstructed transmultiplexer using different modulation techniques: A comparative study

In this paper, an efficient iterative method for design of near-perfect reconstructed transmultiplexer (NPR TMUX) is proposed for the prescribed roll-off factor (RF) and stop band attenuation (As). In this method, windowing technique has been used for the design of prototype filter, and different modulation techniques have been exploited for designing multi-channel transmultiplexer (TMUX). In this method, inter-channel interference (ICI) is iteratively minimized so that it approximately reduces to ideal value zero. Design example is given to illustrate the superiority of the proposed method over earlier reported work. A comparative study of the performance of different modulation techniques for designing TMUX is also presented.