scholarly journals ESTIMATING MAXIMUM PLAUSIBLE CONSERVED SYNTENY BETWEEN ORTHOLOGOUS GENOMES OF A SPECIES PAIR COMPARED IN AN EXHAUSTIVE SEARCH-SPACE

2016 ◽  
Vol 3 ◽  
pp. 1-9
Symmetry ◽  
2020 ◽  
Vol 12 (12) ◽  
pp. 2021
Author(s):  
Ahmad Asrul Ibrahim ◽  
Khairuddin Khalid ◽  
Hussain Shareef ◽  
Nor Azwan Mohamed Kamari

This paper proposes a technique to determine the possible optimal placement of the phasor measurement unit (PMU) in power grids for normal operating conditions. All possible combinations of PMU placement, including infeasible combinations, are typically considered in finding the optimal solution, which could be a massive search space. An integer search algorithm called the bounded search technique is introduced to reduce the search space in solving a minimum number of PMU allocations whilst maintaining full system observability. The proposed technique is based on connectivity and symmetry constraints that can be derived from the observability matrix. As the technique is coupled with the exhaustive technique, the technique is called the bounded exhaustive search (BES) technique. Several IEEE test systems, namely, IEEE 9-bus, IEEE 14-bus, IEEE 24-bus and IEEE 30-bus, are considered to showcase the performance of the proposed technique. An initial Monte Carlo simulation was carried out to evaluate the capability of the bounded search technique in providing a smaller feasible search space. The effectiveness of the BES technique in terms of computational time is compared with the existing exhaustive technique. Results demonstrate that the search space can be reduced tremendously, and the computational burden can be eased, when finding the optimal PMU placement in power grids.


Author(s):  
Tomasz Jastrzęb ◽  
Zbigniew J. Czech ◽  
Wojciech Wieczorek

AbstractThe computationally hard problem of finite language decomposition is investigated. A finite language L is decomposable if there are two languages L1 and L2 such that L = L1L2. Otherwise, L is prime. The main contribution of the paper is an adaptive parallel algorithm for finding all decompositions L1L2 of L. The algorithm is based on an exhaustive search and incorporates several original methods for pruning the search space. Moreover, the algorithm is adaptive since it changes its behavior based on the runtime acquired data related to its performance. Comprehensive computational experiments on more than 4000 benchmark languages generated over alphabets of various sizes have been carried out. The experiments showed that by using the power of parallel computing the decompositions of languages containing more than 200000 words can be found. Decompositions of languages of that size have not been reported in the literature so far.


Sensors ◽  
2020 ◽  
Vol 20 (21) ◽  
pp. 6140 ◽  
Author(s):  
Hassaan Hydher ◽  
Dushantha Nalin K. Jayakody ◽  
Kasun T. Hemachandra ◽  
Tharaka Samarasinghe

Deployment of unmanned aerial vehicles (UAVs) as aerial base stations (ABSs) has been considered to be a feasible solution to provide network coverage in scenarios where the conventional terrestrial network is overloaded or inaccessible due to an emergency situation. This article studies the problem of optimal placement of the UAVs as ABSs to enable network connectivity for the users in such a scenario. The main contributions of this work include a less complex approach to optimally position the UAVs and to assign user equipment (UE) to each ABS, such that the total spectral efficiency (TSE) of the network is maximized, while maintaining a minimum QoS requirement for the UEs. The main advantage of the proposed approach is that it only requires the knowledge of UE and ABS locations and statistical channel state information. The optimal 2-dimensional (2D) positions of the ABSs and the UE assignments are found using K-means clustering and a stable marriage approach, considering the characteristics of the air-to-ground propagation channels, the impact of co-channel interference from other ABSs, and the energy constraints of the ABSs. Two approaches are proposed to find the optimal altitudes of the ABSs, using search space constrained exhaustive search and particle swarm optimization (PSO). The numerical results show that the PSO-based approach results in higher TSE compared to the exhaustive search-based approach in dense networks, consuming similar amount of energy for ABS movements. Both approaches lead up to approximately 8-fold energy savings compared to ABS placement using naive exhaustive search.


2012 ◽  
Vol 15 (08) ◽  
pp. 1250081
Author(s):  
DUSTIN ARENDT ◽  
YANG CAO

It is usually difficult to reverse engineer a simple rule that exhibits some desirable and interesting behavior. We approach this problem by searching for dimer automaton rules exhibiting a broadly defined behavior, self-organization. We expected the simple and asynchronous nature of dimer automata to hinder self-organization, but an exhaustive search quickly yielded three rules that do, in fact, exhibit properties of self-organization. Two of these rules are applicable to actual physical phenomena, motivating searching for additional, more complex rules. However, exhaustive searches scale poorly here because of the rarity of interesting rules combined with the fast growth rate of the search space. To address these challenges we developed the evolutionary motifs algorithm. This algorithm finds the building blocks of the previously found dimer automaton rules, and combines them to form new rules in an evolutionary manner. Our evolutionary algorithm was more effective than an exhaustive search, producing a diverse population of rules exhibiting self-organization.


2010 ◽  
Vol 03 (04) ◽  
pp. 715-729
Author(s):  
L. K. Waters

Consider an M × N chess board with each space colored one of K colors. A chromatic rectangle is a rectangular collection of spaces with all four corner spaces colored the same. An M × N : K NCR board is an M × N board for which there exists a K coloring with no chromatic rectangles. If every K coloring includes a chromatic rectangle, then that board is called an M × N : K CR board. The classification as NCR versus CR has been settled for K ∈ {1, 2, 3} and all positive integers N and M. Note that transposition, or interchanging rows, columns, or colors, will preserve the existence of chromatic rectangles within a coloring. With this in mind, two colorings of a board are called equivalent if one can be produced from the other by such manipulations. This paper establishes that all 10 × 10 : 3 NCR colorings are equivalent. The results stem from characterizations of NCR colorings. These characterizations permit devising and implementing a backtracking algorithm for finding NCR colorings within a significantly restricted search space. In the 10 × 10 : 3 case, the restricted search space is small enough to complete an exhaustive search in about an hour. Several NCR colorings for larger boards, with K > 3, are also included.


Author(s):  
JAMES BILITSKI

The artificial mouth is a robotic device that simulates a human mouth. It consists of moveable lips and an adjustable air supply. In this study the use of a genetic algorithm to compute air pressure and lip pressure values so that the artificial mouth can correctly play five notes on a brass instrument is investigated. In order to properly play a brass instrument, a player must apply proper tension between the lips and apply proper airflow so that the lips vibrate at the proper frequency. A fast search algorithm was needed because it takes about 4 seconds to measure the frequency produced by each combination of pressure parameters. This measurement is slow because of the slow moving mechanics of the system and a delay produced while the notes are measured for pitch. The efficiency of this algorithm was compared to an exhaustive search. Experimentation was performed using various combinations of genetic parameters, including population size, crossover rate, and mutation rate. The genetic search was shown to be about 10 times faster than the exhaustive search because the genetic algorithm searches only very small portions of the search space.


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