With the arrival of the era of big data, the scale of network has grown at an incredible rate, which has brought challenges to community discovery. Local community discovery is a kind of community discovery that does ...
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ISBN:
(数字)9783030050900
ISBN:
(纸本)9783030050900;9783030050894
With the arrival of the era of big data, the scale of network has grown at an incredible rate, which has brought challenges to community discovery. Local community discovery is a kind of community discovery that does not need to know global information about network. A quantity of local community discovery algorithms have been put forward by researchers. Traditional local community discovery generally needs to define local community modularity Q, and greedily add nodes to the community when DQ > 0, which is easy to fall into the local optimal solution. Inspired by the ideal of simulated annealing, greedy algorithm with probability LCDGAP is proposed to detect local community in this paper, which can be applied to all algorithms that perform greedy addition. We permit that the node can be aggregated into the community with a certain probability when DQ < 0. At the same time, we guarantee that this probability will be getting smaller with the increase of program running time, ensuring the program's convergence and stability. Experimental result proves that LCDGAP performs effectively not only in real-world dataset but also computer-generated dataset.
Wireless sensor networks (WSNs) is believed to be the first of the top ten technologies that will change the world in the future. With the development of WSNs in the military and commercial fields, the security of WSN...
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ISBN:
(纸本)9781424413119
Wireless sensor networks (WSNs) is believed to be the first of the top ten technologies that will change the world in the future. With the development of WSNs in the military and commercial fields, the security of WSNs is becoming more and more important. The classical security mechanisms, namely authentication and encryption, can prevent some outsider attacks;however, these mechanisms are inefficient in detecting selective forwarding attacks on compromised nodes. Based on the observations above, in this paper, an improved greedy algorithm based on reputation evaluation mechanism is proposed to enforce cooperation among the nodes of WSNs and defend against the selective forwarding attacks. The performance of the improved greedy algorithm is verified by simulation, and the simulation result shows that the proposed algorithm can effectively resist the attacks of internal malicious nodes, it has better performance than the original greedy algorithm in terms of packet delivery ratio and drop ratio while there exist attack nodes.
This paper proposes a new technique of state estimation (SE) for electric power systems. In the proposed scheme, the Phasor Measurement Units (PMU) are first placed optimally using greedy algorithm for cost reduction,...
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ISBN:
(纸本)9781467385879
This paper proposes a new technique of state estimation (SE) for electric power systems. In the proposed scheme, the Phasor Measurement Units (PMU) are first placed optimally using greedy algorithm for cost reduction, while complete observability of system is also obtained. The SE uses a linear measurement model to obtain the estimated states directly, without any iteration, thereby improves the quality of the estimated data base. To reveal the efficacy of the proposed scheme it has been tested on standard IEEE 5-bus, 14-bus, 30-bus, 57-bus and 118-Bus test systems and the test results are presented.
In this paper, we consider the problem of optimizing lifetime consumption under a habit formation model, both with and without an exogenous pension. Unlike much of the existing literature, we apply a power utility to ...
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In this paper, we consider the problem of optimizing lifetime consumption under a habit formation model, both with and without an exogenous pension. Unlike much of the existing literature, we apply a power utility to the ratio of consumption to habit, rather than to their difference. The martingale/duality method becomes intractable in this setting, so we develop a greedy version of this method that is solvable using Monte Carlo simulation. We investigate the behavior of the greedy solution, and explore what parameter values make the greedy solution a good approximation to the optimal one.
Materialized views aim to improve the response time of analytical queries posed on a data warehouse. This entails that they contain information that provides answers to most future queries. The selection of such infor...
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ISBN:
(纸本)9783642167317
Materialized views aim to improve the response time of analytical queries posed on a data warehouse. This entails that they contain information that provides answers to most future queries. The selection of such information from the data warehouse is referred to as view selection. View selection deals with selection of appropriate sets of views to improve the query response time. Several view selection algorithms exist in literature, most of them being greedy based. The greedy algorithm HRUA, which selects top-k views from a multidimensional lattice, is considered the most fundamental greedy based algorithm. It selects views having the highest benefit, computed in terms of size, for materialization. Though the views selected using HRUA are beneficial with respect to size, they may not account for a large number of future queries and may hence become an unnecessary overhead. This problem is addressed by the Query Answering greedy algorithm (QAGA) proposed in this paper. QAGA uses both the size of the view, and the frequency of previously posed queries answered by each view, to compute the profits of all views in each iteration. Thereafter it selects, from among them, the most profitable view for materialization. QAGA is able to select views which are beneficial with respect to size and have a greater likelihood of answering future queries. Further, experimental results show that QAGA, as compared to HRUA, is able to select views capable of answering greater number of queries. Though HRUA incurs a lower total cost of evaluating all the views, QAGA has a lower total cost of answering all the queries leading to an improvement in the average query response time. This in turn facilitates decision making.
Measuring software similarity base on software design artifacts has been one of the research topics in software engineering. Software similarity measurement is used in software reuse, clone detection, and learning ass...
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ISBN:
(纸本)9781728114743
Measuring software similarity base on software design artifacts has been one of the research topics in software engineering. Software similarity measurement is used in software reuse, clone detection, and learning assessment. Previous research focus on universal modeling language design artifacts. These design artifacts concern on the semantic and structure of a set of objects within a system and their interaction with themselves and objects outside the system. There are also design artifacts that model how data or information transformed into different forms, sizes, and time. This study focus on developing diagram similarity measurement base on one of those artifacts, i.e., object-oriented data flow diagrams. The measurement uses the greedy approach to calculate the similarity score of two diagrams using four elements derived from elements of object oriented data flow diagram, i.e. external entities, processes, data stores, and classes. The initial experimentation result shows that the proposed diagram similarity measurement is feasible.
Speckle is a significant problem that hinders optical heterodyne signal detection via the array detector method, with the efficiency of existing phase compensation algorithms severely limited by the number of array el...
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Speckle is a significant problem that hinders optical heterodyne signal detection via the array detector method, with the efficiency of existing phase compensation algorithms severely limited by the number of array elements. This study simplifies the original phase compensation model and proposes a phase compensation calculation method based on a greedy algorithm. Numerical and experimental results show that the proposed algorithm is stable and 3-4 orders of magnitude faster than the others, avoiding the performance degradation typically associated with an increasing array number, enabling real-time data processing. This suggests that high application potential in areas such as synthetic aperture lidar and laser vibration measurement.
作者：
Fink, JiriHurink, Johann L.Univ Twente
Fac Elect Engn Math & Comp Sci POB 217 NL-7500 AE Enschede Netherlands Charles Univ Prague
Fac Math & Phys Dept Theoret Comp Sci & Math Log Malostranske Namesti 25 Prague 11800 Czech Republic
This paper studies a planning problem for heating water. Hereby, boilers (e.g. gas or electric boilers, heat pumps or microCHPs) are used to heat the water and store it for domestic demands. We consider a simple boile...
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This paper studies a planning problem for heating water. Hereby, boilers (e.g. gas or electric boilers, heat pumps or microCHPs) are used to heat the water and store it for domestic demands. We consider a simple boiler which is either turned on or turned off and has a buffer of limited capacity. The energy needed to run the boiler has to be bought on a day-ahead market, so we are interested in a planning which minimizes the cost to supply the boiler with energy. We present a greedy algorithm whose time complexity is O(T alpha(T)) where T is the number of time intervals and alpha is the inverse of Ackermann function. (C) 2021 Elsevier B.V. All rights reserved.
The binary quadratic programming problem (BQP) is an NP-hard problem and has a large number of applications. In this paper, an iterated greedy algorithm with k-opt local search (IGKLS) is proposed for the BQP. Iterate...
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ISBN:
(纸本)9781467327435;9781467327428
The binary quadratic programming problem (BQP) is an NP-hard problem and has a large number of applications. In this paper, an iterated greedy algorithm with k-opt local search (IGKLS) is proposed for the BQP. Iterated greedy (IG) algorithm has already been applied to a variety of optimization problems, and shown to be simple but with excellent search performance. The proposed iterated greedy algorithm consists of two central phases, destruction and construction phases. As a local search algorithm, k-opt local search is applied after the construction phase. The computational results showed that the proposed iterated greedy algorithm outperformed state-of-the-art methods for huge size BQP instances.
Finding the optimization of power allocation of subcarrier is always a challenge in MIMO-OFDMA schemes in order to maximize the capacity of the system. Resources allocation is process how set of network is decide in w...
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ISBN:
(纸本)9781509011780
Finding the optimization of power allocation of subcarrier is always a challenge in MIMO-OFDMA schemes in order to maximize the capacity of the system. Resources allocation is process how set of network is decide in wireless system. This research is to study restriction of proportional rate and total power among user in MIMO-OFDMA scheme and the power allocation and capacity of subcarrier in the scheme. The objectives are to suggest by using greedy Power Allocation for capacity increment in MIMO-OFDMA system and to evaluate the system by greedy Subcarrier Allocation. Simulation results show that the proposed algorithm can improve the capacity of the network compared with the waterfilling when using signal-to-noise ratio (SNR) with value 6dB. The proposed algorithm shows comparison between the noise to sub-channel ratio and power allocation in the midst of data sub-channel for 25, 75 and 100 users. It shows that there is no significant difference in power allocation of data subcarriers even if the number of users is increased.
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