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linear programing formulations and algorithms for radiotherapy treatment planning

OPTIMIZATION METHODS & SOFTWARE 2006年第2期21卷 201-231页

作者： Olafsson, A Wright, SJ Univ Wisconsin Dept Comp Sci Madison WI 53706 USA Univ Wisconsin Dept Ind Engn Madison WI 53706 USA

Optimization has become an important tool in treatment planning for cancer radiation therapy. It may be used to determine beam weights, beam directions, and appropriate use of beam modifiers such as wedges and blocks, with the aim of delivering a required dose to the tumor, while sparing nearby critical structures and normal tissue. linear programing formulations are a core computation in many approaches to treatment planning, because of the abundance of highly developed linear programing software. However, these formulations of treatment planning often require a surprisingly large amount of time to solve - more than might be anticipated given the dimensions of the problems. Moreover, the choices of formulation, algorithm, and pivot rule that perform best from a computational viewpoint are sometimes not obvious, and the software's default choices are sometimes poor. This article considers several linear programing formulations of treatment planning problem and tests several variants of simplex and interior-point methods for solving them. Conclusions are drawn about the most effective formulations and variants.

关键词： linear programing simplex method interior-point method radiation therapy

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linear programing models for portfolio optimization using a benchmark

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EUROPEAN JOURNAL OF FINANCE 2019年第5期25卷 435-457页

作者： Park, Seyoung Song, Hyunson Lee, Sungchul Sungkyunkwan Univ Stat Dept Seoul South Korea Yonsei Univ Dept Math & Computat Sci & Engn Seoul South Korea

We consider the problem of constructing a perturbed portfolio by utilizing a benchmark portfolio. We propose two computationally efficient portfolio optimization models, the mean-absolute deviation risk and the Dantzig-type, which can be solved using linear programing. These portfolio models push the existing benchmark toward the efficient frontier through sparse and stable asset selection. We implement these models on two benchmarks, a market index and the equally-weighted portfolio. We carry out an extensive out-of-sample analysis with 11 empirical datasets and simulated data. The proposed portfolios outperform the benchmark portfolio in various performance measures, including the mean return and Sharpe ratio.

关键词： Mean-absolute deviation risk Dantzig portfolio optimization perturbation sparsity linear programing

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Incorporating linear programing and life cycle thinking into environmental sustainability decision-making: a case study on anchovy canning industry

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CLEAN TECHNOLOGIES AND ENVIRONMENTAL POLICY 2017年第7期19卷 1897-1912页

作者： Garcia-Herrero, I. Laso, J. Margallo, M. Bala, A. Gazulla, C. Fullana-i-Palmer, P. Vazquez-Rowe, I. Irabien, A. Aldaco, R. Univ Cantabria Dept Ingn Quim & Biomol Avda Castros S-N E-39005 Santander Spain UPF Life Cycle & Climate Change ESCI Passeig Pujades 1 Barcelona 08003 Spain Lavola Cosostenibilidad Rbla Catalunya 6 Barcelona 08007 Spain Pontificia Univ Catolica Peru Peruvian LCA Network Dept Engn Ave Univ 1801 San Miguel Peru

Life cycle assessment (LCA) is a powerful tool to support environmental informed decisions among product and process alternatives. LCA results reflect the process stage contributions to several environmental impacts, which should be made mutually comparable to help in the decision-making process. Aggregated environmental indexes enable the translation of this set of metrics into a one final score, by defining the attached weights to impacts. Weighting values reflect the corresponding relevance assigned to each environmental impact. Current weighing schemes are based on pre-articulation of preferences, without considering the specific features of the system under study. This paper presents a methodology that combines LCA methodology and linear programming optimisation to determine the environmental improvement actions that conduct to a more sustainable production. LCA was applied using the environmental sustainability assessment methodology to obtain two main indexes: natural resources (NR) and environmental burdens (EB). Normalised indexes were optimised to determine the optimal joint of weighting factors that lead to an optimised global Environmental Sustainability Index. The proposed methodology was applied to a food sector, in particular, to the anchovy canning industry in Cantabria Region (Northern Spain). By maximising the objective function composed of NR and EB variables, it is possible to find the optimal joint of weights that identify the best environmental sustainable options. This study proves that LCA can be applied in combination with linear programing tools as a part of the decision-making process in the development of more sustainable processes and products.

关键词： Anchovy Canning industry Life cycle assessment Optimisation linear programing

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Designing low-cost "heart healthy bread": Optimization using linear programing and 15-country comparison

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BMC Nutrition 2016年第1期2卷 1-10页

作者： Wilson, Nick Nghiem, Nhung Ryan, Sian Cleghorn, Christine Nair, Nisha Blakely, Tony Department of Public Health University of Otago Wellington PO Box 7343 Wellington New Zealand

Background: Bread is an important component of the diet in many countries and provides needed nutrients but also typically too much of other nutrients e.g., sodium. We therefore aimed to use linear programing to determine the optimal design of low-cost "heart healthy bread"(HHB) and to compare the results with commercial breads in 15 countries. Methods: Optimization using linear programing focused on achieving set loaf prices (at NZ$1.5 and $3) and for a range of minimal sodium levels. Then within those constraints, levels of alpha-linolenic acid (ALA) were maximized, then dietary fiber, and then polyunsaturated fatty acids. Data from New Zealand (NZ) was used for the HHB designs and comparison nutrient and price data came from breads in 15 high-income countries. Results: The optimized loaf costing NZ$1.50 in ingredients (HHB$1.5) was superior to the commercial white loafs in three out of the eight heart health nutrient categories. The optimized loaf that was high in linseed and cost NZ$3 in ingredients (HHB$3), was nutritionally superior to the commercial loafs with seeds/nuts in six out of the eight heart health categories (i.e., in terms of sodium, potassium, fatty acid ratio and fiber). In terms of value-per-weight, a commercial white loaf from the UK was slightly cheaper than the HHB$1.50 loaf (at US$0.07 vs US$0.10 per 100 g loaf). But compared to the other seed/nut loafs, the HHB$3 loaf was the best value at US$0.17 per 100 g, vs a mean of US$0.85 per 100 g across international comparators. Conclusions: This proof-of-concept study suggests it is possible to design breads that are nutritionally superior to commercially available breads from a heart health perspective, as well as being lower cost. Such HHB designs could be promoted by health agencies and utilized in conjunction with a government-funded bread voucher system for those at high risk of cardiovascular disease. © 2016 Wilson et al.

关键词： Alpha-linolenic acid Bread design Cardiovascular disease Fiber linear programing Optimization Saturated fat Sodium

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Lean Service Model for Maintenance Management Using a linear programing Approach 10

Lean Service Model for Maintenance Management Using a Linear...

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10th International Conference on Industrial Technology and Management (ICITM)

作者： Damian, Maria Chambilla, Maribel Viacava, Gino Eyzaguirre, Juan Raymundo, Carlos Univ Peruana Ciencias Aplicadas Ingn Ind Lima Peru Univ Peruana Ciencias Aplicadas Direcc Invest Lima Peru

ISBN: (纸本)9781665435857

This research proposed a design for a maintenance management model through lean service methodology to be applied in SMEs performing green area maintenance. The study aimed to determine the optimal maintenance process to enhance productivity. We proposed the implementation of tools, such as the work method, linear programing, and preventive maintenance, which helped efficiently standardize activities and optimize resources. We further implemented a linear programing approach to allocate properly employees and thus minimize downtime. These steps provided considerable benefits for companies and their customers;productivity increased from 77.5% to 86.6% with the application of these tools.

关键词： productivity lean service linear programing work method maintenance management efficiency

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Static Output Feedback Controller Design for Constrained MIMO Discrete-Time Positive System

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JOURNAL OF CONTROL AUTOMATION AND ELECTRICAL SYSTEMS 2025年第1期36卷 9-19页

作者： Bolajraf, Mohamed Abdelmalek Essaadi Univ Natl Sch Appl Sci Tetouna Dept Telecommun Ave 9 Avril Tetouan 2117 Morocco

This paper is concerned with synthesis problems for constrained multi-input multi-output (MIMO) discrete-time linear positive systems. First, the stabilization problem by taking static output feedback controller has been solved. The designed controller ensure the positivity and the asymptotic stability of the unconstrained closed-loop system. More precisely, necessary and sufficient conditions on the existence of such controller are established, and the desired gain matrix can be calculated easily through the solution of the proposed linear programming (LP) problem. Furthermore, MIMO discrete-time linear positive systems with constraints on the control inputs, or on the state variables are considered. For such systems, different constrained stabilization problems are formulated when static output feedback controller is used. Moreover, it is shown that these problems are solvable in terms of LP problems. In addition, we show how the obtained results can be extended to maximize the domain of attraction of the constrained discrete-time positive system. Finally, theoretical results are supported by a numerical simulation, and also by an application to certain pests dynamic process.

关键词： Stabilization Positive discrete-time linear systems Static output feedback linear programing Constrained controller

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Eric Ed013541: the Relationship of Learner Characteristics to Media Stimuli and programing Sequences

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2016年

[Auto Generated] 1.1 Purpose of the Study Page 5 6 2.0 METHODS 7 2.1 Subjects 2.2 Basic Design 2.3 Procedures 8 2.4 Environment 8 2.5 Developmental Test Population 9 2.6 Statistical Techniques and Computer Programs 9 3.0 RESULTS 11 3.1 Total IQ Score 11 3.2 Other Learner Characteristics 11 3.3 programing and Stimuli Modes 25 4.o DISCUSSION 37 4.1 Discussion of Hypotheses 37 11.2 Patterns Relating to Each Learner Characteristic 38 5.0 CONCLUSIONS 43 5.1 For this Study 43 5.2 The Findings as They

关键词： academic ability auditory stimuli branching characteristics ed013541: eric archive ethnic origins experiments filep, robert t. grade 8 instructional films intelligence learner learning linear programing media natural sciences programed instruction programing projection equipment sex (characteristics) socioeconomic status teaching machines visual stimuli

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New consumer-dependent energy management system to reduce cost and carbon impact in smart buildings

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SUSTAINABLE CITIES AND SOCIETY 2018年 39卷 740-750页

作者： Haidar, Nour Attia, Mohamed Senouci, Sidi-Mohammed Aglzim, El-Hassane Kribeche, Ali Asus, Zainab Binti Univ Bourgogne Franche Comte DRIVE EA1859 F-58000 Nevers France Univ Teknol Dept Appl Mech & Design Skudai Johor Malaysia

Buildings represent one of the most important energy consumers (about 40% and 55% of total U.S. and European energy consumption, respectively) and are regarded as non-negligible greenhouse gases emitters (39% of total greenhouse gases emission in U.S.). Hence, it becomes crucial to control buildings energy consumption in order to preserve energy resources and reduce greenhouse gases. For this reason, we propose in this paper a real time Consumer-Dependent Energy Management System (CD-EMS) in MicroGrids (i.e. a restricted form of the power grid) for smart buildings. The main new idea is to find a trade-off between the energy cost, either renewable or non-renewable, and its carbon impact. The other innovation is to transform the building manager to a Consum-Actor who participates directly on reducing greenhouse gas emission by fixing a consumer's acceptability margin that allows buying renewable energy, even if it is a little more expensive than non-renewable one. CD-EMS offers the best compromise between decreasing energy cost and reducing gas emissions. The problem is modeled as a linear program, resolved by Matlab, and implemented in a small-scale datacenter building prototype. The obtained results show a noticeable improvement in terms of cost and carbon impact where we prove that our system is able to reduce cost until 7.3%, and CO2 emission until 55.7%.

关键词： Energy management system Microgrid Energy storage management Cost minimization Carbon minimization linear programing Smart buildings

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Optimization of a Close-Fitting Volume RF Coil for Brain Imaging at 6.5 mT Using linear Programming

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IEEE TRANSACTIONS ON BIOMEDICAL ENGINEERING 2021年第4期68卷 1106-1114页

作者： Shen, Sheng Xu, Zheng Koonjoo, Neha Rosen, Matthew S. State Key Lab Power Transmiss Equipment & Syst Se Beijing Peoples R China MGH AA Martinos Ctr Biomed Imaging Charlestown MA 02129 USA Chongqing Univ State Key Lab Power Transmiss Equipment & Syst Se Chongqing 400044 Peoples R China Harvard Univ Dept Phys Cambridge MA 02138 USA Harvard Med Sch Boston MA 02115 USA

Objective: The use of a close-fitting roughly head-shaped volume coil for MRI (magnetic resonance imaging) has the merit of improving the filling factor and thus the SNR (signal-to-noise ratio) from the brain. However, the surface of the RF coil follows that of the head which makes it difficult to determine an optimal coil winding pattern. We describe here a new method to optimize a head-shaped RF coil with the objective of maximizing its SNR and RF-magnetic-field homogeneity for operation at ultra-low magnetic field (6.5 mT, 276 kHz). Methods: The approach consists of FEM (finite-element-method) simulation and linear programing based optimization. Results: We have implemented the optimization and further studied the relationship between the design requirements and the performance of the RF coil. Finally, we constructed an optimal RF coil and scanned both a head-shaped phantom and a human subject. Conclusion: The method we outline here provide new insight into the conductor layout needed for magnetic optimization of structurally complex coils, especially when tradeoffs between competing attributes (SNR and homogeneity in this case) must be made.

关键词： Radio frequency Magnetic resonance imaging Magnetic fields Signal to noise ratio Wires Finite element analysis RF coil optimization FEM simulation linear programing Ultra-low field MRI

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Graphs with many edge-colorings such that complete graphs are rainbow

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DISCRETE APPLIED MATHEMATICS 2023年第1期333卷 151-164页

作者： Bastos, Josefran de O. Hoppen, Carlos Lefmann, Hanno Oertel, Andy Schmidt, Dionatan R. Univ Fed Ceara Sobral Brazil Univ Fed Rio Grande Do Sul Porto Alegre Brazil Techn Univ Chemnitz Chemnitz Germany Lund Univ Lund Sweden

We consider a version of the Erdos-Rothschild problem for families of graph patterns. For any fixed k > 3, let r0(k) be the largest integer such that the following holds for all 2 < r < r0(k) and all sufficiently large n: The Turan graph Tk-1(n) is the unique n-vertex graph G with the maximum number of r-edge-colorings such that the edge set of any copy of Kk in G is rainbow. We use the regularity lemma of Szemeredi and linear programming to obtain a lower bound on the value of r0(k). For a more general family P of patterns of Kk, we also prove that, in order to show that the Turan graph Tk-1(n) maximizes the number of P-free r-edge-colorings over n-vertex graphs, it suffices to prove a related stability result.(c) 2023 Elsevier B.V. All rights reserved.

关键词： Rainbow colorings Erdos-Gallai problem Regularity lemma linear programing

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