检索结果-内蒙古大学图书馆

Accuracy and speed of splitting methods for three-dimensional space-time fractional diffusion equation with ψ-Caputo derivatives

引用

MATHEMATICS AND COMPUTERS IN SIMULATION 2021年 188卷 226-240页

作者： Bohaienko, V. O. NAS Ukraine VM Glushkov Inst Cybernet Glushkov Ave 40 Kiev Ukraine

The paper deals with finite-difference schemes for a three-dimensional diffusion equation with psi-Caputo derivative with respect to the time and space variables. Theoretical and experimental estimates of accuracy and performance of implicit and splitting schemes are given. Finite-difference schemes are combined with algorithms that accelerate computations on the base of fixed memory principle and expansion of integral operator kernel into series. Computational experiments are conducted on a test problem that has an analytical solution for the case of the Caputo-Katugampola derivative. In the experiments we focus on the issue of interdependence between accuracy and speed of calculations. Based on the obtained estimates, we present an algorithm for automatic selection of optimal computational scheme. (C) 2021 International Association for Mathematics and Computers in Simulation (IMACS). Published by Elsevier B.V. All rights reserved.

关键词： Fractional differential equations psi-Caputo derivative Finite-difference method Splitting schemes optimal algorithm

来源：评论

学校读者我要写书评

暂无评论

Improved approximation algorithms for two-stage flexible flow shop scheduling

引用

JOURNAL OF COMBINATORIAL OPTIMIZATION 2021年第1期41卷 28-42页

作者： Peng, Anzhen Liu, Longcheng Lin, Weifeng Xiamen Univ Sch Math Sci Xiamen 361005 Peoples R China

A two-stage flexible flow shop scheduling is a manufacturing infrastructure designed to process a set of jobs, in which a single machine is available at the first stage and m parallel machines are available at the second stage. At the second stage, each task can be processed by multiple parallel machines. The objective is to minimize the maximum job completion time, i.e., the makespan. Sun et al. (J Softw 25:298-313, 2014) presented an O(n log n)-time 3-approximation algorithm for F2(1, Pm) vertical bar size(i)vertical bar C-max under some special conditions. Zhang et al. (J Comb Optim 39:1-14, 2020) presented a 2.5-approximation algorithm for F2(1, P2) vertical bar line(i)vertical bar C-max and a 2.67-approximation algorithm for F2(1, P3) vertical bar line(i)vertical bar C-max, which both run in linear time. In this paper, we achieved following improved results: for F2(1, P2) vertical bar line(i)vertical bar C-max, we present an O(n log n)-time 2.25-approximation algorithm, for F2(1, P3) vertical bar line(i)vertical bar C-max, we present an O(n log n)-time 7/3-approximation algorithm, for F2(1, Pm) vertical bar size(i)vertical bar C-max with the assumption min(1 <= i <= n) {p1(i)} >= max(1 <= i <= n) {p2i}, we present a linear time optimal algorithm.

关键词： Scheduling Two-stage flow shop Approximation algorithm optimal algorithm

来源：评论

学校读者我要写书评

暂无评论

Robust Capacity Planning for Project Management

引用

INFORMS JOURNAL ON COMPUTING 2021年第4期33卷 1533-1550页

作者： Conejo, Antonio J. Hall, Nicholas G. Long, Daniel Zhuoyu Zhang, Runhao Ohio State Univ Dept Integrated Syst Engn Columbus OH 43210 USA Ohio State Univ Dept Management Sci Columbus OH 43210 USA Chinese Univ Hong Kong Dept Syst Engn & Engn Management Shatin Hong Kong Peoples R China

We consider a significant problem that arises in the planning of many projects. Project companies often use outsourced providers that require capacity reservations that must be contracted before task durations are realized. We model these decisions for a company that, given partially characterized distributional information, assumes the worst-case distribution for task durations. Once task durations are realized, the project company makes decisions about fast tracking and outsourced crashing, to minimize the total capacity reservation, fast tracking, crashing, and makespan penalty costs. We model the company's objective using the target-based measure of minimizing an underperformance riskiness index. We allow for correlation in task performance, and for piecewise linear costs of crashing and makespan penalties. An optimal solution of the discrete, nonlinear model is possible for small to medium size projects. We compare the performance of our model against the best available benchmarks from the robust optimization literature, and show that it provides lower risk and greater robustness to distributional information. Our work thus enables more effective risk minimization in projects, and provides insights about how to make more robust capacity reservation decisions. Summary of Contribution: This work studies a financially significant planning problem that arises in project management. Companies that face uncertainties in project execution may need to reserve capacity with outsourced providers. Given that decision, they further need to plan their operational decisions to protect against a bad outcome. We model and solve this problem via adjustable distributionally robust optimization. While this problem involves two-stage decision making, which is computationally challenging in general, we develop a computationally efficient algorithm to find the exact optimal solution for instances of practical size.

关键词： project management capacity reservation adjustable distributionally robust optimization optimal algorithm

来源：评论

学校读者我要写书评

暂无评论

A Novel Secondary optimal Control for Multiple Battery Energy Storages in a DC Microgrid

引用

IEEE TRANSACTIONS ON SMART GRID 2020年第5期11卷 3716-3725页

作者： Zhou, Jianyu Shi, Mengxuan Chen, Yin Chen, Xia Wen, Jinyu He, Haibo Huazhong Univ Sci & Technol State Key Lab Adv Electromagnet Engn & Technol Wuhan 430074 Peoples R China Huazhong Univ Sci & Technol Sch Elect & Elect Engn Wuhan 430074 Peoples R China Univ Strathclyde Dept Elect & Elect Engn Glasgow G1 1XW Lanark Scotland Univ Rhode Isl Dept Elect Biomed & Comp Engn Kingston RI 02881 USA

The distributed controller consisting of a voltage controller and a power controller is commonly employed on the secondary control layer in the DC microgrid. In this paper, a novel optimal control based on the PI consensus algorithm is proposed for multiple battery energy storages (BESs) in an islanded DC microgrid. Compared with the conventional distributed voltage controller, the proposed scheme improves the system robustness to time delays. The steady-state analysis is conducted to verify that the proposed scheme can take effect in case of time delays. The impact of the secondary controller on the dynamics of the system under time delays is investigated by the eigenvalue analysis. Simulation results confirm that favorable power sharing and DC voltage regulation as well as robustness to time delays achieved by optimal control in an islanded microgrid with multiple BESs and constant power load (CPL).

关键词： DC microgrid battery energy storage distributed control optimal algorithm

来源：评论

学校读者我要写书评

暂无评论

Uncertainties and errors in algorithms for elevation gradients

引用

INTERNATIONAL JOURNAL OF GEOGRAPHICAL INFORMATION SCIENCE 2021年第2期35卷 296-320页

作者： Shi, Dong Yang, Qinke Zhu, Qifeng Jupp, David L. B. Long, Yongqing Northwest Univ Coll Urban & Environm Sci Xian Peoples R China Shaanxi Inst Zool Qinling Giant Panda Conservat & Res Ctr Xian Peoples R China CSIRO Land & Water Canberra ACT Australia

Elevation gradients are primary components of slope and aspect. Significant concerns remain when computing gradients if noise (perturbing non-DEM data) is present. There is still a need to find ways to balance accuracy of the gradient and stability to noise for specific types of DEM. In this study, six algorithms are compared using four DEMs and analyzed for stability to base level DEM noise and added random noise. Theoretical stability and accuracy of the formulae are analyzed using harmonic (frequency or spatial scale) response. The results provide a basis to determine the most appropriate algorithm for different situations. They show that: (1) the set (Evans-Young (EY), Sharpnack (Sp), Sobel (Sb)) has a better stability to noise ratio than the set (Zevenbergen (Z), Florinsky (F), Horn (H)). EY has the smoothest surface and the highest stability to noise ratio. If stability is the primary measure in mid-frequencies, EY is a good choice. (2) Sb is good because of its accuracy in mid to high frequencies. Out to the highest frequencies, Sb is the best. (3) F has potential but should not be used with very high-frequency noise. (4) H and Z should not be used when there is substantial noise.

关键词： Elevation gradient optimal algorithm harmonic response stability accuracy

来源：评论

学校读者我要写书评

暂无评论

Minimum Consistent Subset Problem for Trees 23rd

Minimum Consistent Subset Problem for Trees

引用

23rd International Symposium on Fundamentals of Computation Theory (FCT)

作者： Dey, Sanjana Maheshwari, Anil Nandy, Subhas C. Indian Stat Inst ACM Unit Kolkata India Carleton Univ Sch Comp Sci Ottawa ON Canada

ISBN: (纸本)9783030865931;9783030865924

In the minimum consistent subset (MCS) problem, a connected simple undirected graph G = (V, E) is given in which each vertex is colored by one of the possible colors {c(1), c(2), ..., c(k)};the objective is to compute a minimum size subset C subset of V such that for each vertex v is an element of V, one of its nearest neighbors in C, with respect to the hop-distance, is of the same color as the color of v. The decision version of the MCS problem is NP-complete even for planar graphs. We propose a polynomial-time algorithm for computing a minimum consistent subset of a bi-chromatic tree.

关键词： Consistent subset Graphs Trees optimal algorithm

来源：评论

学校读者我要写书评

暂无评论

MinSum Movement of Barrier and Target Coverage using Sink -based Mobile Sensors on the Plane 41

MinSum Movement of Barrier and Target Coverage using Sink -b...

引用

41st IEEE International Conference on Distributed Computing Systems (ICDCS)

作者： Guo, Longkun Zou, Wenjie Wu, Chenchen Xu, Dachuan Du, Dingzhu Qilu Univ Technol Sch Comp Sci & Technol Jinan Peoples R China Fuzhou Univ Coll Math & Comp Sci Fuzhou Peoples R China Tianjin Univ Technol Coll Sci Tianjin Peoples R China Beijing Univ Technol Dept Operat Res & Info Eng Beijing Peoples R China Univ Texas Dallas Dept Comp Sci Richardson TX 75083 USA

ISBN: (纸本)9781665445139

Emerging IoT applications have brought up new coverage problems with sink-based mobile sensors. In this paper, we first focus on the MinSum Sink-based Line Barrier Coverage (SLBC) problem of covering a line barrier with mobile sensors originated at sink stations distributed on the plane. The objective is to minimize the movement sum of the sensors for the sake of energy efficiency. When the sinks emit sensors with non -uniform radii, we prove the MinSum SLBC problem is AT -complete via reducing from the Partition problem that is known ArPcomplete. Then for the MinSum Sink -based on -a -Line Target Coverage (SLTC) problem of covering targets on a line, an exact algorithm is presented based on grouping the targets and transforming to the shortest path problem in the auxiliary graph induced by the vertices corresponding to the groups. The algorithm runs in time 0 (n2) when sinks emit sensors of uniform sensing radius, and in time 0 (I42122) for sensors of non-uniform radii, where n and R are respectively the number of targets and different radii. Eventually for SLBC, we propose a pseudo additive fully polynomial -time approximation scheme by extending the algorithm for SLTC. The algorithm runs in 0 (k2 (E) 2) time and computes a coverage with total movement provably bounded by opt+ for any fixed sufficiently small > 0, where opt, k and L are respectively the movement of an optimum solution, the number of sinks and the length of the barrier. At last, experiments are carried out to demonstrate the practical performance gain of our algorithms.

关键词： Barrier coverage target coverage optimal algorithm NP-complete approximation algorithm sink station

来源：评论

学校读者我要写书评

暂无评论

Scheduling UET-UCT DAGs of Depth Two on Two Processors 22

Scheduling UET-UCT DAGs of Depth Two on Two Processors

引用

22nd International Arab Conference on Information Technology (ACIT)

作者： Quaddoura, Ruzayn Samara, Gassan Zarqa Univ Dept Comp Sci Zarqa Jordan

ISBN: (纸本)9781665419956

Given n unit execution time (UET) tasks whose precedence constraints form a directed acyclic graph (DAG), the arcs are associated with unit communication time (UCT) delays. The problem is to schedule the tasks on two processors in order to minimize the makespan. Several polynomial algorithms in the literature are proposed for special classes of digraphs, but the complexity of solving this problem in general case stills a challenging open question. We propose in this paper a linear time algorithm to compute an optimal schedule for the class of DAGs of depth two.

关键词： Scheduling makespan precedence constraints optimal algorithm

来源：评论

学校读者我要写书评

暂无评论

Linear time algorithm for computing min-max movement of sink-based mobile sensors for line barrier coverage

引用

CONCURRENCY AND COMPUTATION-PRACTICE & EXPERIENCE 2022年第2期34卷

作者： Zou, Wenjie Guo, Longkun Huang, Peihuang Lin, Geng Mei, Hengquan Fuzhou Univ Coll Math & Comp Sci Fuzhou Peoples R China Qilu Univ Technol Sch Comp Sci Room 420 Jinan 250353 Peoples R China Minjiang Univ Coll Math & Data Sci Fuzhou Peoples R China

Witnessing broad energy-critical applications of barrier coverage in mobile and wireless sensor networks, emerging practical applications have recently brought a new barrier coverage model which uses sink-based mobile sensors for covering a given barrier with the aim of prolonging the lifespan of the coverage. In the model, a set of sink stations were distributed on the plane in which each sink can emit mobile sensors with an identical radius. The task is to cover a given line barrier with the emitted mobile sensors, aiming to minimize the maximum movement of the sensors so as to prolong the shortest lifespan among the sensors in coverage. In this paper, we first devise an algorithm for optimally solving the problem based on the properties of the structures called movement parity and tangent equilibrium points between the sinks. Then based on a more sophisticated geometric property of optimum solutions, we improve the runtime to a linear runtime O(k) which attains the possibly optimum runtime of the problem for k being the number of sinks. At last, numerical experiments are carried out to demonstrate the practical performance gain of our algorithms against baselines in literature.

关键词： barrier coverage equilibrium min‐ max movement optimal algorithm sink station

来源：评论

学校读者我要写书评

暂无评论

An optimal algorithm for computing the non-trivial circuits of a union of iso-oriented rectangles

引用

INFORMATION PROCESSING LETTERS 2013年第3期113卷 55-59页

作者： Alevizos, Panagiotis D. Univ Patras Dept Math GR-26500 Patras Greece

Given n rectangles R-1, ..., R-n on the plane with sides parallel to the coordinate axes, Lipski and Preparata (1981) [1] have presented a Theta(n log n) time and O(n log n) space algorithm for computing the non-trivial circuits of the union u = R-1 boolean OR ... boolean OR R-n. In this paper, we are presenting a simple algorithm, which computes the non-trivial circuits of u in Theta(n log n) time and Theta(n) space. (C) 2012 Elsevier B.V. All rights reserved.

关键词： Computational geometry Circuit Contour Rectilinear polygons optimal algorithm Sweep plane

来源：评论

学校读者我要写书评

暂无评论

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案：

请选择收藏分类：

通借通还

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：