检索结果-内蒙古大学图书馆

作者： Siyuan Liu Feng Qi Shaoyong Guo Linna Ruan State Key Laboratory of Networking and Switching Technology Beijing University of Posts and Telecommunications

The domain name system(DNS) is an important infrastructure in the network, and its main function is to provide users with domain name resolution services. The query timeliness of the domain name system is directly related to the access delay of Internet applications and the user's network. Massive domain name resolution requests will occupy network bandwidth and cause resolution delays. An ideal DNS caching mechanism can reduce the bandwidth pressure of resolution and shorten the resolution delay. This paper proposes an edge-side domain name caching algorithm based on group access. Through the processing and classification of domain name resolution logs, domain names are divided into four categories. In addition, this paper designs a caching mechanism(CPGA)based on a greedy algorithm to periodically cache and update different types of domain names. Finally, this paper compares this model with Random strategy and LRU strategy, and the hit rate of domain name resolution has been improved.

关键词： DNS cache Group access greedy algorithm Hit rate

来源：评论

学校读者我要写书评

暂无评论

Exploiting submodularity to quantify near-optimality in multi-agent coverage problems

引用

AUTOMATICA 2019年 100卷 349-359页

作者： Sun, Xinmiao Cassandras, Christos G. Meng, Xiangyu Boston Univ Div Syst Engn Brookline MA 02446 USA Boston Univ Ctr Informat & Syst Engn Brookline MA 02446 USA Univ Sci & Technol Beijing Sch Automat & Elect Engn Beijing 100083 Peoples R China

We consider optimal coverage problems for a multi-agent network aiming to maximize a joint event detection probability in an environment with obstacles. The objective function of this problem is non concave and no global optimum is guaranteed by gradient-based algorithms developed to date. In order to obtain a solution provably close to the global optimum, the selection of initial conditions is crucial. We first formulate the initial agent location generation as an additional optimization problem where the objective function is monotone submodular, a class of functions for which the performance obtained through a greedy algorithm solution is guaranteed to be within a provable bound relative to the optimal performance. We then derive two tighter bounds by exploiting the curvature information (total curvature and elemental curvature) of the objective function. We further show that the tightness of these lower bounds is complementary with respect to the sensing capabilities of the agents. The greedy algorithm solution can be subsequently used as an initial point of a gradient-based algorithm for the original optimal coverage problem. Simulation results are included to verify that this approach leads to significantly better performance relative to previously used algorithms. (C) 2018 Elsevier Ltd. All rights reserved.

关键词： Optimal coverage Multi-agent systems Submodular set function greedy algorithm Gradient method

来源：评论

学校读者我要写书评

暂无评论

Droplet movement control using fuzzy logic controller and image processing along with pin valves inside microfluidic device

引用

MEASUREMENT & CONTROL 2019年第9-10期52卷 1517-1531页

作者： Mehmood, Faisal Haider, Zeeshan Farooq, Umar Yin Baoqun Univ Sci & Technol China Dept Automat Hefei 230000 Anhui Peoples R China Univ Sci & Technol China Sch Informat Sci & Technol Dept Biomed Engn Hefei Anhui Peoples R China Zhejiang Univ Coll Informat Sci & Elect Engn Hangzhou Zhejiang Peoples R China

Most of the research studies nowadays are trying to bring automation to biomedical engineering and Lab on a Chip which is fast growing interdisciplinary field and has attracted researchers from various fields. The objective of this paper is to present an overall system to control droplet movement inside microfluidic channel using fuzzy logic controller, image processing algorithm, and microvalves installed within microfluidic channel. A state space model has been derived from circuit analogy approach to describe the microfluidic network. Furthermore, a COMSOL-based study is primed for device structure by means of droplet generation and controlling the droplet through fitted valves. Moreover, an image processing algorithm based on active contours has been proposed in this research to track the movement of the droplet through the channel. This droplet controlling method is utterly based on fuzzy controller as well as camera images to move the droplet at desired position by controlling flow rates inside the fluidic channel using valves installed inside the microfluidic device. The results indicate that the fuzzy logic controller performs much better in terms of stability and faster response as compared to conventional proportional-integral-derivative controller.

关键词： Fuzzy logic controller microfluidic microdroplets greedy algorithm

来源：评论

学校读者我要写书评

暂无评论

Bounds for two static optimization problems on routing and spectrum allocation of anycasting

引用

OPTICAL SWITCHING AND NETWORKING 2019年 31卷 144-161页

作者： Miyagawa, Yasutaka Watanabe, Yosuke Shigeno, Maiko Ishii, Kiyo Takefusa, Atsuko Yoshise, Akiko Univ Tsukuba Tsukuba Ibaraki 3058573 Japan Natl Inst Adv Ind Sci & Technol Tsukuba Ibaraki 3058568 Japan Natl Inst Informat Chiyoda Ku Tokyo 1018430 Japan

Elastic optical networks with optical-orthogonal frequency division multiplexing have been addressed enthusiastically for communication networks in the last decade because they result in high bandwidth efficiency. Routing and spectrum allocation (RSA) problems need to be solved when we transmit demands in an elastic optical network. This research deals with static RSA models for anycast transmission, which is one-to-one-of-many transmission in inter-datacenter networks. Two static RSA optimization models are considered. One minimizes the maximum number of spectrum slots needed to allocate given demands. The other maximizes the traffic volume of demands served under a given spectrum slot number. For both models, lower and upper bounds are developed in order to obtain exact optimal solutions. One-side bounds of the problems are evaluated by relaxing spectrum continuity constraints. For the other side bounds, several greedy algorithms are investigated. We conducted computational experiments to confirm whether relaxation problems can give tight bounds and to determine greedy algorithmic behaviors by using each of route selection criterion and each of demand ordering policies. The results show that the solutions obtained by relaxing spectrum continuity constraints are almost optimal. They also indicate that exact optimal solutions are obtained efficiently by using these bounds.

关键词： Elastic optical network Anycast greedy algorithm Integer linear programming

来源：评论

学校读者我要写书评

暂无评论

Generation of an equipment module database - A maximum coverage problem

引用

CHEMICAL ENGINEERING RESEARCH & DESIGN 2019年 148卷 164-168页

作者： Eilermann, Martin Schach, Constantin Sander, Peer Bramsiepe, Christian Schembecker, Gerhard TU Dortmund Univ Dept Biochem & Chem Engn Lab Plant & Proc Design Emil Figge Str 70 D-44227 Dortmund Germany Evonik Technol & Infrastruct GmbH Paul Baumann Str 1 D-45772 Marl Germany

Current challenges for (bio-)chemical industry require shorter project lead times. To reduce the lead time, the concept of module-based plant design was developed. Suitable equipment modules are selected from an equipment module database instead of time-consuming tailor-made equipment design. The quality of module-based plant design strongly depends on the quality of the equipment module database. An equipment module database should contain the least number of equipment modules covering as many industrial applications as possible. Hence, the generation of an equipment module database is a maximum coverage problem known from other disciplines, such as facility location. Within this work, the corresponding maximum coverage problem is formulated and solved by a randomized greedy algorithm. The approach for the generation of an equipment module database presented is exemplarily applied for liquid/liquid heat transfer applications provided by Evonik. It is shown, that less equipment modules are required for the same coverage of applications if the equipment module database is generated based on the maximum coverage problem than based on the existing methodology presented by Eilermann et al. (2017). Additionally, less computational effort is required. (C) 2019 Published by Elsevier B.V. on behalf of Institution of Chemical Engineers.

关键词： Module-based plant design Equipment module database Maximum coverage problem greedy algorithm

来源：评论

学校读者我要写书评

暂无评论

Diverse data selection via combinatorial quasi-concavity of distance covariance: A polynomial time global minimax algorithm

引用

DISCRETE APPLIED MATHEMATICS 2019年 265卷 182-191页

作者： Vepakomma, Praneeth Kempner, Yulia MIT 77 Massachusetts Ave Cambridge MA 02139 USA Holon Inst Technol Holon Israel

In this paper we show that the negative sample distance covariance function is a quasi-concave set function of samples of random variables that are not statistically independent. We use these properties to propose greedy algorithms to combinatorially optimize some diversity (low statistical dependence) promoting functions of distance covariance. Our greedy algorithm obtains all the inclusion-minimal maximizers of this diversity promoting objective. Inclusion-minimal maximizers are multiple solution sets of globally optimal maximizers that are not a proper subset of any other maximizing set in the solution set. We present results upon applying this approach to obtain diverse features (covariates/variables/predictors) in a feature selection setting for regression (or classification) problems. We also combine our diverse feature selection algorithm with a distance covariance based relevant feature selection algorithm of Kong et al. (2015) to produce subsets of covariates that are both relevant yet ordered in non-increasing levels of diversity of these subsets. (C) 2019 Elsevier B.V. All rights reserved.

关键词： Distance covariance Quasi-concave set function Minimax Maximin Diverse feature selection greedy algorithm Distance correlation Global optima in polynomial time

来源：评论

学校读者我要写书评

暂无评论

SOSP: a stepwise optimal sparsity pursuit algorithm for practical compressed sensing

引用

MULTIMEDIA TOOLS AND APPLICATIONS 2019年第1期78卷 3-26页

作者： Guo, Huijuan Han, Suqing Hao, Fei Park, Doo-Soon Min, Geyong Taiyuan Normal Univ Dept Comp Sci & Technol Taiyuan 030619 Shanxi Peoples R China Shaanxi Normal Univ Sch Comp Sci Xian 710119 Shaanxi Peoples R China Soonchunhyang Univ Dept Comp Software Engn Asan South Korea Univ Exeter Dept Math & Comp Sci Exeter Devon England

Compressed Sensing (CS), as a promising paradigm for acquiring signals, is playing an increasing important role in many real-world applications. One of the major components of CS is sparse signal recovery in which greedy algorithm is well-known for its speed and performance. Unfortunately, in many classic greedy algorithms, such as OMP and CoSaMP, the real sparsity is a key prior information, but it is blind. In another words, the true sparsity is not available for many practical applications. Due to this disadvantage, the performance of these algorithms are significantly reduced. In order to avoid too much dependence of classic greedy algorithms on the true sparsity, this paper proposed an efficient reconstruction greedy algorithm for practical Compressed Sensing, termed stepwise optimal sparsity pursuit (SOSP). Differs from the existing algorithms, the unique feature of SOSP algorithm is that the assumption of sparsity is needed instead of the true sparsity. Hence, the limitations of sparsity in practical application can be tackled. Based on an arbitrary initial sparsity satisfying certain conditions, the SOSP algorithm employs two variable step sizes to hunt for the optimal sparsity step by step by comparing the final reconstruction residues. Since the proposed SOSP algorithm preserves the ideas of original algorithms and innovates the prior information of sparsity, thus it is applicable to any effective algorithm requiring known sparsity. Extensive experiments are conducted in order to demonstrate that the SOSP algorithm offers a superior reconstruction performance in terms of discarding the true sparsity.

关键词： Compressed sensing Sparsity pursuit Estimated sparsity Reconstruction greedy algorithm

来源：评论

学校读者我要写书评

暂无评论

2D Partial Unwinding-A Novel Non-Linear Phase Decomposition of Images

引用

IEEE TRANSACTIONS ON IMAGE PROCESSING 2019年第10期28卷 4762-4773页

作者： Li, Yanting Zhang, Liming Qian, Tao Univ Macau Fac Sci & Technol Dept Math Taipa 999078 Macao Peoples R China Univ Macau Dept Comp & Informat Sci Fac Sci & Technol Taipa 999078 Macao Peoples R China Macau Univ Sci & Technol Macau Inst Syst Engn Taipa 999078 Macao Peoples R China

This paper aims at proposing a novel 2D non-linear phase decomposition of images, which performs the image processing tasks better than the traditional Fourier transformation (linear phase decomposition), but further, it has additional mathematical properties allowing more effective image analysis, including adaptive decomposition components and positive instantaneous phase derivatives. 1D unwinding Blaschke decomposition has recently been proposed and studied. Through factorization it expresses arbitrary 1D signal into an infinite linear combination of Blaschke products. It offers fast converging positive frequency decomposition in the form of rational approximation. However, in the multi-dimensional cases, the usual factorization mechanism does not work. As a consequence, there is no genuine unwinding decomposition for multi-dimensions. In this paper, a 2D partial unwinding decomposition based on algebraic transforms reducing multi-dimensions to the 1D case is proposed and analyzed. The result shows that the fast convergence offers efficient image reconstruction. The tensor type decomposing terms are mutually orthogonal, giving rise to 2D positive frequency decomposition. The comparison results show that the proposed method outperforms the standard greedy algorithm and the most commonly used methods in the Fourier category. An application in watermarking is presented to demonstrate its potential in applications.

关键词： Fourier transform hardy space greedy algorithm adaptive Fourier decomposition unwinding Blaschke decomposition Nevanlinna factorization

来源：评论

学校读者我要写书评

暂无评论

Optimal placement of imperfect water quality sensors in water distribution networks

引用

COMPUTERS & CHEMICAL ENGINEERING 2019年 121卷 200-211页

作者： de Winter, Casper Palleti, Venkata Reddy Worm, Daniel Kooij, Robert Erasmus Univ Erasmus Sch Econ Rotterdam Netherlands Singapore Univ Technol & Design Ctr Res Cyber Secur iTrust Singapore Singapore TNO Cyber Secur & Robustness The Hague Netherlands Univ Technol Delft Fac Elect Engn Math & Comp Sci Delft Netherlands

Water Distribution Networks (WDNs) are often susceptible to either accidental or deliberate contamination which can lead to poisoned water, many fatalities and large economic consequences. In order to protect against these intrusions or attacks, an efficient sensor network with a limited number of sensors should be placed in a WDN. In this paper, we focus on optimal sensor placements by introducing two greedy-based algorithms in which the imperfection of sensors and multiple objectives can be taken into account. The algorithms were tested using a medium scale urban WDN. It is shown that our algorithms are able to find sensor placements in reasonable time and that its solutions are close to optimal. Furthermore, relaxing the often used assumption that sensors work perfectly results in different sensor placements than were found before, indicating the importance to take sensor imperfection into account when placing sensors. (C) 2018 Elsevier Ltd. All rights reserved.

关键词： Water distribution networks Sensor placements Contaminant detection Imperfect sensors greedy algorithm

来源：评论

学校读者我要写书评

暂无评论

Resource Management in Multicloud IoT Radio Access Network

引用

IEEE INTERNET OF THINGS JOURNAL 2019年第2期6卷 3014-3023页

作者： Awais, Muhammad Ahmed, Ashfaq Ali, Syed Azhar Naeem, Muhammad Ejaz, Waleed Anpalagan, Alagan COMSATS Univ Islamabad Wah Campus Dept Elect & Comp Engn Wah Cantonment 47040 Pakistan Univ Engn & Technol Dept Elect Engn Taxila 47050 Pakistan Thompson Rivers Univ Dept Appl Sci & Engn Kamloops BC V2C 0C8 Canada Ryerson Univ Dept Elect & Comp Engn Toronto ON M5B 2K3 Canada

Cloud radio access network (CRAN) is a promising approach to provide ubiquitous and on demand access to future Internet of Things (IoT) networks. The existing CRANs assume a single cloud which suffers from computational complexity and signaling latency to support massive number of IoT devices in large scale network deployments. This paper focuses on the scheduling of IoT devices in a multicloud IoT network scenario. This paper considers the downlink of an IoT network consisting of multiple clouds, each coordinates a cluster of several base stations (BSs) allowing joint signal processing. The transmit frame of each BS is composed of several resource blocks (RBs). The multiple clouds are linked to the central cloud which performs scheduling of IoT devices and synchronization of transmit frames. The work models the IoT devices to RBs assignment problem considering the intercloud and intracloud interference. The optimization problem maximizes the overall network utilization under practical network constraints. Further, this paper also proposes a low complexity heuristic algorithm to solve the constraint resource allocation problem in linear time. Complexity analysis of proposed algorithm is carried out and simulations results for a number of IoT network scenarios demonstrate that proposed solution is numerically accurate and performs close to the optimal solution.

关键词： greedy algorithm Internet of Things (IoT) radio access networks resource allocation

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：