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RF peak power reduction in CAIPIRINHA excitation by interslice phase optimization

NMR IN BIOMEDICINE 2015年第11期28卷 1393-1401页

作者： Sbrizzi, Alessandro Poser, Benedikt A. Tse, Desmond H. Y. Hoogduin, Hans Luijten, Peter R. van den Berg, Cornelis A. T. Univ Med Ctr Utrecht Imaging Div Utrecht Netherlands Maastricht Univ Fac Psychol & Neurosci Maastricht Netherlands Maastricht Univ Med Ctr Dept Radiol Maastricht Netherlands

The purpose of this work was to show that the overall peak power of RF pulses for CAIPIRINHA excitation can be substantially reduced by applying interslice phase relaxation. The optimal phases are scan dependent and can be quickly calculated by the proposed method. The multi-band RF pulse design is implemented as the minimization of a linear objective function with quadratic constraints. The interslice phase is considered to be a variable for optimization. In the case of a phase cycling scheme (CAIPIRINHA), the peak power is considered over all pulses. The computation time (about 1s) is compatible with online RF pulse design. It is shown that the optimal interslice phases depend on the CAIPIRINHA scheme used and that RF peak power is reduced when the CAIPIRINHA phase cycling is taken into account in the optimization. The proposed method is extremely fast and results in RF pulses with low peak power for CAIPIRINHA excitation. The MATLAB implementation is given in the appendix;it allows for online determination of scan-dependent phase parameters. Furthermore, the method can be easily extended to pTx shimming systems in the context of multi-slice excitations, and this possibility is included in the software. Copyright (c) 2015 John Wiley & Sons, Ltd.

关键词： RF pulse design CAIPIRINHA multi-band RF peak power interslice phase relaxation simultaneous multi-slice active-set linear program

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THE DYNAMIC BERTH ALLOCATION PROBLEM: A linearIZED FORMULATION

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RAIRO-OPERATIONS RESEARCH 2015年第3期49卷 473-494页

作者： Simrin, Ahmed Diabat, Ali Masdar Inst Sci & Technol Dept Engn Syst & Management Abu Dhabi U Arab Emirates

International shipping is a multi-billion dollar business which has undergone significant growth during the last decade. Considerable benefits could be gained by improving and optimizing container terminal operations. One specific challenge facing container terminals is the berth allocation problem, referred to as (BAP). In this paper, a new formulation is proposed for the dynamic berth allocation problem (DBAP). Initially the problem was formulated as a non-linear mixed integer program, followed by incorporating techniques to present an equivalent mixed integer program (MIP). A genetic algorithm (GA) heuristic was developed and applied to different instances of the problems, and through computational experiments the best, average, and worst case performances were analyzed to determine the efficiency of the algorithms.

关键词： Container terminal linear program non-linear program dynamic berth allocation

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An inference-proof approach to privacy-preserving horizontally partitioned linear programs

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OPTIMIZATION LETTERS 2014年第1期8卷 267-277页

作者： Hong, Yuan Vaidya, Jaideep Rutgers State Univ Management Sci & Informat Syst Dept Newark NJ 07102 USA Rutgers State Univ CIMIC Newark NJ 07102 USA

Mangasarian (Optim. Lett., 6(3), 431-436, 2012) proposed a constraints transformation based approach to securely solving the horizontally partitioned linear programs among multiple entities-every entity holds its own private equality constraints. More recently, Li et al. (Optim. Lett., doi: 10.1007/s11590-011-0403-2, 2012) extended the transformation approach to horizontally partitioned linear programs with inequality constraints. However, such transformation approach is not sufficiently secure - occasionally, the privately owned constraints are still under high risk of inference. In this paper, we present an inference-proof algorithm to enhance the security for privacy-preserving horizontally partitioned linear program with arbitrary number of equality and inequality constraints. Our approach reveals significantly less information than the prior work and resolves the potential inference attack.

关键词： linear program Privacy Security Horizontally partitioned data

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A Homogeneous Smoothing-type Algorithm for Symmetric Cone linear programs

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Acta Mathematicae Applicatae Sinica 2014年第3期30卷 647-662页

作者： Wei-Zhe GU Zheng-Hai HUANG Department of Mathematics School of ScienceTianjin University

In this paper, we investigate a smoothing-type algorithm for solving the symmetric cone linear program （（SCLP） for short） by making use of an augmented system of its optimality conditions. The algorithm only needs to solve one system of linear equations and to perform one line search at each iteration. It is proved that the algorithm is globally convergent without assuming any prior knowledge of feasibility/infeasibility of the problem. In particular, the algorithm may correctly detect solvability of （SCLP）. Furthermore, if （SCLP） has a solution, then the algorithm will generate a solution of （SCLP）, and if the problem is strongly infeasible, the algorithm will correctly detect infeasibility of （SCLP）.

关键词： linear program symmetric cone Euclidean Jordan algebra smoothing algorithm global conver-gence

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Parametric optimization with uncertainty on the left hand side of linear programs

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COMPUTERS & CHEMICAL ENGINEERING 2014年 60卷 31-40页

作者： Khalilpour, Rajab Karimi, I. A. Natl Univ Singapore Dept Chem & Biomol Engn Singapore 117576 Singapore

Although parametric optimization with uncertainties on the objective function (OF) or on the so-called "right-hand-side" (RHS) of the constraints has been addressed successfully in recent papers, very little work exists on the same with uncertainties on the left-hand-side (LHS) of the constraints or in the coefficients of the constraint matrix. The goal of this work has been to develop a systematic method to solve such parametric optimization problems. This is a very complex problem and we have begun with the simplest of optimization problems, namely the linear programming problem with a single parameter on the LHS. This study reviews the available work on parametric optimization, describes the challenges and issues specific to LHS parametric linear programming (LHS-pLP), and presents a solution algorithm using some classic results from matrix algebra. (C) 2013 Elsevier Ltd. All rights reserved.

关键词： Parametric programming Left-hand-side Uncertainty linear program LP

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Stochastic Model Predictive Control for Optimal Economic Operation of a Residential DC Microgrid

Stochastic Model Predictive Control for Optimal Economic Ope...

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IEEE International Conference on Industrial Technology (ICIT)

作者： Gulin, Marko Matusko, Jadranko Vasak, Mario Univ Zagreb Fac Elect Engn & Comp Lab Renewable Energy Syst Zagreb 41000 Croatia

ISBN: (纸本)9781479978007

In this paper we present power flow optimization of a residential DC microgrid that consists of photovoltaic array, batteries stack and fuel cells stack with electrolyser, and is connected to the grid via bidirectional power converter. The optimization problem aims to minimize microgrid operating costs and is formulated using a linear program that takes into account the storages charge and discharge efficiency. To account for power predictions uncertainty, optimization problem is defined in a stochastic framework by using chance constraints. Since we assume that the error in realization of power predictions will he compensated by utility grid, chance constraints are defined for power exchange between the microgrid and the utility grid. Finally, we investigate a stochastic model predictive control for the closed-loop power management in the microgrid. Performance verification of the proposed approach is performed on simulations for two-month period.

关键词： Microgrid Stochastic Model Predictive Control linear program Power Flow Optimization Chance Constraints

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A New Procedure for Solving Integer linear programming Problems

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ARABIAN JOURNAL FOR SCIENCE AND ENGINEERING 2014年第6期39卷 5265-5269页

作者： Tantawy, S. F. Helwan Univ Dept Math Fac Sci Cairo 11795 Egypt

This paper presents a new procedure for solving the integer linear programming problem when the objective function is a linear function and the set of constraints is in the form of linear inequality constraints. The proposed procedure is based on the conjugate gradient projection method together with the use of the spirit of Gomory cut. The main idea behind our method is to move through the feasible region through a sequence of points in the direction that improves the objective function. Since methods based on vertex information may have difficulties as the problem size increases, therefore, the present method can be considered as an interior point method, which had been proved to be less sensitive to problem size. A simple production example is given to clarify the theory of this new procedure.

关键词： linear program Integer linear programming Conjugate gradient

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Energy and Cost Minimization of Bidirectional Frequency Regulation Service by EV Following FERC Order 755

Energy and Cost Minimization of Bidirectional Frequency Regu...

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General Meeting of the IEEE-Power-and-Energy-Society

作者： Mojdehi, Mohammad Nikkhah Ghosh, Prasanta Fardad, Makan Syracuse Univ Dept Elect Engn & Comp Sci Syracuse NY 13244 USA

ISBN: (纸本)9781467380409

Increasing share of renewable energy sources in the electric sector, forces the system operators to include new resources for frequency regulations with fast ramping. Electric vehicles (EVs) with fast charging and short battery reaction time are becoming promising source for frequency regulations. Therefore, it is worthwhile to evaluate EV's abilities and associated cost to participate in the frequency regulation activity. In this paper, we first present a linear model of EV operating in charging/discharging mode and impact of battery degradation during these activities. We then define a cost function for EV operation and its minimization using linear programming. After calculating the optimal operating points of EV, a novel framework was developed to calculate optimal bidding components of EV, regulation capacity and energy cost function to participate in the regulation market. Simulation results show the efficiency of the developed linear model. Results also provide pathways for possible opportunities of revenue stream for the EV owner, by offering the regulation up/down services, without limiting the EV owners level of comfort.

关键词： electric vehicle frequency regulation linear program battery degradation

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The OPF Model and Algorithm for "Source-Grid Load" Interactive Optimal Regulation Participated with Flexible Load 5

The OPF Model and Algorithm for "Source-Grid Load" Interacti...

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5th International Conference on Electric Utility Deregulation and Restructuring and Power Technologies (DRPT)

作者： Li, Qi Cui, Xueshen Jiang, Limin Guo, Bingqing Yang, Xu North China Elect Power Univ Sch Elect Engn Beijing Peoples R China China Elect Power Res Inst Inst Power Supply & Efficiency Beijing Peoples R China Beijing HUASHANG Energy Management Ltd Co Beijing Peoples R China

ISBN: (纸本)9781467371063

Flexible load has increasingly becoming an important means of regulating the power grid and consuming new energy, as well as an important part of "source-grid-load" coordination control. On the other hand, nowadays typical new energy resources such as wind and solar energy are being accessed to the power grid in a large scale, but the phenomenon of abandoning wind or solar energy is very serious since the effect of channel bottlenecks or little load consumption. Aiming at solving this problem, and combining with the possibility of adjusting load flexibly because of the loose electricity price in the new situation of Chinese electric power reform, this paper gives the DC OPF model for the "source-grid-load" interactive optimal regulation based on the traditional OPF model. To be precise, this model puts forward the goal of maximizing the system-wide social net marginal benefit, which is on the basic of any time section with balanced power flow in the system, and considers the marginal cost of the source and network side as well as the net marginal benefit of the load side, to research the optimization operation strategy of the large-scale new energy, conventional power and flexible load. Then linear program algorithm is deduced based on basic mathematics model foundation. The example is simulated under the goal of maximizing the social net marginal benefit with MATLAB/linprog, the results show the effectiveness of the model and algorithm. There is no convergence problems in the model and algorithm presented in this paper. In addition, the compute speed is fast. On the one hand, the scheduling decision can meet the security, economy, reliability and other operational requirements of the power system. On the other hand, the regulation value of the "source-grid-load" interaction which participated with flexible load can be fully reflected. In a word, this paper provides new ideas of OPF for future "relatively independent" power dispatching / trading platform.

关键词： optimal power flow "source-grid-load" interaction DC power flow social net marginal benefit linear program

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Embedded Second-Order Cone programming with Radar Applications

Embedded Second-Order Cone Programming with Radar Applicatio...

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IEEE High Performance Extreme Computing Conference (HPEC)

作者： Mountcastle, Paul Henretty, Tom Naqvi, Aale Lethin, Richard Reservoir Labs Inc New York NY 10012 USA

ISBN: (纸本)9781467392860

Second-order cone programming (SOCP) is required for the solution of underdetermined systems of linear equations with complex coefficients, subject to the minimization of a convex objective function. This type of computational problem appears in compressed radar sensing, where the goal is to reconstruct a sparse image in a generalized space of phase model parameters whose dimension is higher than the number of complex measurements. In order to enforce sparsity in the final rectified radar image, the sum of moduli of a complex vector, called the l(1) norm, must be minimized. This norm differs from what is ordinarily encountered in compressed sensing for digital photographic data and video, in that the convex optimization that must be performed involves an SOCP rather than a linear program. We illustrate the role of this type of optimization in radar signal processing by means of examples. The examples point to a significant generalization that encompasses and unifies a wide class of radar signal processing algorithms that can be implemented in software by means of SOCP solvers. Finally, we show how modern SOCP solvers are optimized for efficient solution of these problems in the context of embedded signal processing on small autonomous platforms.

关键词： convex programming image reconstruction linear programming radar imaging complex vector compressed radar sensing convex objective function convex optimization digital photographic data digital photographic video embedded second-order cone programming embedded signal processing final rectified radar image linear equations linear program phase model parameters radar applications radar signal processing small autonomous platforms sparse image reconstruction underdetermined systems Compressed sensing Image reconstruction Imaging Mathematical model Radar imaging Radar signal processing

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