Browsing by Subject "Simulated annealing"
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Item Open Access Application mapping algorithms for mesh-based network-on-chip architectures(Springer New York LLC, 2015-03) Tosun, S.; Ozturk, O.; Ozkan, E.; Ozen, M.Due to shrinking technology sizes, more and more processing elements and memory blocks are being integrated on a single die. However, traditional communication infrastructures (e.g., bus or point-to-point) cannot handle the synchronization problems of these large systems. Using network-on-chip (NoC) is a step towards solving this communication problem. Energy- and communication-efficient application mapping is a previously studied problem for mesh-based NoC architectures; however, there is still need for intelligent mapping algorithms since current algorithms either take too much running time or do not determine accurate results. To fill this need, in this study, we propose two mapping algorithms (one based on simulated annealing and one based on genetic algorithm) for energy- and communication-aware mapping problems of mesh-based NoC architectures. We compare these two algorithms with an integer linear programming-based method and a heuristic method using several multimedia and synthetic benchmarks.Item Open Access Assembly line balancing using genetic algorithms(Kluwer Academic Publishers, 2000) Sabuncuoğlu İ.; Erel, E.; Tanyer, M.Assembly Line Balancing (ALB) is one of the important problems of production/operations management area. As small improvements in the performance of the system can lead to significant monetary consequences, it is of utmost importance to develop practical solution procedures that yield high-quality design decisions with minimal computational requirements. Due to the NP-hard nature of the ALB problem, heuristics are generally used to solve real life problems. In this paper, we propose an efficient heuristic to solve the deterministic and single-model ALB problem. The proposed heuristic is a Genetic Algorithm (GA) with a special chromosome structure that is partitioned dynamically through the evolution process. Elitism is also implemented in the model by using some concepts of Simulated Annealing (SA). In this context, the proposed approach can be viewed as a unified framework which combines several new concepts of AI in the algorithmic design. Our computational experiments with the proposed algorithm indicate that it outperforms the existing heuristics on several test problems.Item Open Access Balancing of U-type assembly systems using simulated annealing(Taylor & Francis, 2001) Erel, E.; Sabuncuoğlu İ.; Aksu, B. A.The paper presents a new simulated annealing (SA)-based algorithm for the assembly line-balancing problem with a U-type con®guration. The proposed algorithm employs an intelligent mechanism to search a large solution space. U-type assembly systems are becoming increasingly popular in today’s modern production environments since they are more general than the traditional assem- bly systems. In these systems, tasks are to be allocated into stations by moving forward and backward through the precedence diagram in contrast to a typical forward move in the traditional assembly systems. The performance of the algorithm is measured by solving a large number of benchmark problems available in the literature. The results of the computational experiments indicate that the proposed SA-based algorithm performs quite eŒectively. It also yields the optimal solution for most problem instances. Future research directions and a compre- hensive bibliography are also provided here.Item Open Access Computer aided frequency planning for the radio and TV broadcasts(Institute of Electrical and Electronics Engineers, 1996-06) Altıntaş, Ayhan; Ocalı, O.; Topçu, Satılmış; Tanyer, S. G.; Köymen, HayrettinThe frequency planning of the VHF and UHF broadcasts in Turkey is described. This planning is done with the aid of computer databases and digital terrain map. The frequency offset is applied whenever applicable to increase the channel capacity. The offset assignment is done through simulated annealing algorithm. The international rules and regulations concerning Turkey are also considered.Item Open Access Customer order scheduling problem: a comparative metaheuristics study(Springer, 2007) Hazır, Ö.; Günalay, Y.; Erel, E.The customer order scheduling problem (COSP) is defined as to determine the sequence of tasks to satisfy the demand of customers who order several types of products produced on a single machine. A setup is required whenever a product type is launched. The objective of the scheduling problem is to minimize the average customer order flow time. Since the customer order scheduling problem is known to be strongly NP-hard, we solve it using four major metaheuristics and compare the performance of these heuristics, namely, simulated annealing, genetic algorithms, tabu search, and ant colony optimization. These are selected to represent various characteristics of metaheuristics: nature-inspired vs. artificially created, population-based vs. local search, etc. A set of problems is generated to compare the solution quality and computational efforts of these heuristics. Results of the experimentation show that tabu search and ant colony perform better for large problems whereas simulated annealing performs best in small-size problems. Some conclusions are also drawn on the interactions between various problem parameters and the performance of the heuristics.Item Open Access The design of finite-state machines for quantization using simulated annealing(IEEE, 1993) Kuruoğlu, Ercan Engin; Ayanoğlu, E.In this paper, the combinatorial optimization algorithm known as simulated annealing is used for the optimization of the trellis structure or the next-state map of the decoder finite-state machine in trellis waveform coding. The generalized Lloyd algorithm which finds the optimum codebook is incorporated into simulated annealing. Comparison of simulation results with previous work in the literature shows that this combined method yields coding systems with good performance.Item Open Access Design of trellis waveform coders with near-optimum structure(IET, 1992) Kuruoglu, E.E.; Ayanoglu, E.In this Letter the combinatorial optimisation algorithm known as simulated annealing is used for the optimisation of the trellis structure of the next-state map of the decoder finite-state machine in trellis waveform coding. The generalised Lloyd algorithm which finds the optimum codebook is incorporated into simulated annealing so that near-optimum coding systems are designed. Comparison of simulation results with previous work in the literature shows that this method yields better coding systems than those published in the literature.Item Open Access Efficient simulated annealing based solution approaches to the competitive single and multiple allocation hub location problems(Elsevier, 2018) Ghaffarinasab, N.; Motallebzadeh, A.; Jabarzadeh, Y.; Kara, Bahar Y.Hub location problems (HLPs) constitute an important class of problems in logistics with numerous applications in passenger/cargo transportation, postal services, telecommunications, etc. This paper addresses the competitive single and multiple allocation HLPs where the market is assumed to be a duopoly. Two firms (decision makers) sequentially decide on the configuration of their hub networks trying to maximize their own market shares. The customers choose one firm based on the cost of service provided by these firms. Mathematical formulations are presented for the problems of the first and second firms (the leader and the follower, respectively) and Simulated Annealing (SA) based solution algorithms are proposed for solving these problems both in single and multiple allocation settings. Extensive computational experiments show the capability of the proposed solution algorithms to obtain the optimal solutions in short computational times. Some managerial insights are also derived based on the obtained results.Item Open Access Examining the annealing schedules for RNA design algorithm(IEEE, 2016-07) Erhan, H. E.; Sav, Sinem; Kalashnikov, S.; Tsang, H. H.RNA structures are important for many biological processes in the cell. One important function of RNA are as catalytic elements. Ribozymes are RNA sequences that fold to form active structures that catalyze important chemical reactions. The folded structure for these RNA are very important; only specific conformations maintain these active structures, so it is very important for RNA to fold in a specific way. The RNA design problem describes the prediction of an RNA sequence that will fold into a given RNA structure. Solving this problem allows researchers to design RNA; they can decide on what folded secondary structure is required to accomplish a task, and the algorithm will give them a primary sequence to assemble. However, there are far too many possible primary sequence combinations to test sequentially to see if they would fold into the structure. Therefore we must employ heuristics algorithms to attempt to solve this problem. This paper introduces SIMARD, an evolutionary algorithm that uses an optimization technique called simulated annealing to solve the RNA design problem. We analyzes three different cooling schedules for the annealing process: 1) An adaptive cooling schedule, 2) a geometric cooling schedule, and 3) a geometric cooling schedule with warm up. Our results show that an adaptive annealing schedule may not be more effective at minimizing the Hamming distance between the target structure and our folded sequence's structure when compared with geometric schedules. The results also show that warming up in a geometric cooling schedule may be useful for optimizing SIMARD. © 2016 IEEE.Item Open Access Fault-tolerant topology generation method for application-specific network-on-chips(Institute of Electrical and Electronics Engineers, 2015) Tosun, S.; Ajabshir, V. B.; Mercanoglu, O.; Ozturk, O.As the technology sizes of integrated circuits (ICs) scale down rapidly, current transistor densities on chips dramatically increase. While nanometer feature sizes allow denser chip designs in each technology generation, fabricated ICs become more susceptible to wear-outs, causing operation failure. Even a single link failure within an on-chip fabric can halt communication between application blocks, which makes the entire chip useless. In this paper, we aim to make faulty chips designed with network-on-chip (NoC) communication usable. Specifically, we present fault-tolerant irregular topology-generation method for application-specific NoC designs. Designed NoC topology allows different routing path if there is a link failure on the default routing path. Additionally, we present a simulated annealing-based application mapping algorithm aiming to minimize total energy consumption of the NoC design. We compare fault-tolerant topologies with nonfault-tolerant application-specific irregular topologies on energy consumption, performance, and area using multimedia benchmarks and custom-generated graphs. Our results demonstrate that our method is able to determine fault-tolerant topologies with negligible area increase and better energy values.Item Open Access Generating short-term observation schedules for space mission projects(Kluwer Academic Publishers, 1999) Aktürk, M. S.; Kılıç, K.In this paper, we propose a new dispatching rule and a set of local search algorithms based on the filtered beam search, GRASP and simulated annealing methodologies to construct short-term observation schedules of space mission projects, mainly for NASA's Hubble Space Telescope (HST). The main features of generating short-term observations of HST are state dependent set up times, user specified deadlines, visibility windows of the targets and the priorities assigned to the observations. The objective of HST scheduling is to maximize the scientific return. We have tested the relative performances of the proposed algorithms including the nearest neighbor rule both in objective function value and computational time aspects by utilizing a full-factorial experimental design.Item Open Access A local search heuristic with self-tuning parameter for permutation flow-shop scheduling problem(IEEE, 2009) Dengiz, B.; Alabaş-Uslu, Ç.; Sabuncuoğlu, İhsanIn this paper, a new local search metaheuristic is proposed for the permutation flow-shop scheduling problem. In general, metaheuristics are widely used to solve this problem due to its NP-completeness. Although these heuristics are quite effective to solve the problem, they suffer from the need to optimize parameters. The proposed heuristic, named STLS, has a single self-tuning parameter which is calculated and updated dynamically based on both the response surface information of the problem field and the performance measure of the method throughout the search process. Especially, application simplicity of the algorithm is attractive for the users. Results of the experimental study show that STLS generates high quality solutions and outperforms the basic tabu search, simulated annealing, and record-to-record travel algorithms which are well-known local search based metaheuristics.Item Open Access Membrane-mediated interactions between disk-like inclusions adsorbed on vesicles(Frontiers Media S.A., 2022-10-17) Alizadeh-Haghighi, Elnaz; Karaei Shiraz, Arash; Bahrami, Amir HoushangSelf-assembly of membrane inclusions plays a key role in biological processes such as cellular signalling and trafficking and has potential applications for designing interfacial devices such as sensors and actuators. Despite intensive studies of curvature-mediated interactions, how membrane curvature modulates interactions between flat disk-like inclusions, adsorbed on vesicles, remains unknown. We use Monte Carlo simulations of a triangulated vesicle with simulated annealing to explore curvature-mediated interactions between disk-like rigid inclusions, induced by membrane elastic energy. We distinguish two distinct short and long-range curvature-mediated interactions for disk distances below and above the vesicle diameter. We observe short-range neutral interactions in the limit of small disks, where the vesicle appears as a flat bilayer to the disks. Beyond a certain size of disk-like inclusions, we find a transition from neutral to attractive short-range forces. Consistent with experiments, we also show that upon deflating vesicles, previously-attracted disks experience repulsive interactions. Our findings show how the vesicle curvature and the relative size between the disks and the vesicle determine the character of membrane-mediated interactions between adsorbed disk-like inclusions. Copyright © 2022 Alizadeh-Haghighi, Karaei Shiraz and Bahrami.Item Open Access New heuristic for the dynamic layout problem(Palgrave Macmillan, 2003) Erel, E.; Ghosh, J. B.; Simon, J. T.The dynamic layout problem addresses the situation where the traffic among the various units within a facility changes over time. Its objective is to determine a layout for each period in a planning horizon such that the total of the flow and the relocation costs is minimized. The problem is computationally very hard and has begun to receive attention only recently. In this paper, we present a new heuristic scheme, based on the idea of viable layouts, which is easy to operationalize. A limited computational study shows that, depending upon how it is implemented, this scheme can be reasonably fast and can yield results that are competitive with those from other available solution methods.Item Open Access Robot move sequence determining and multiple part-type scheduling in hybrid flexible flow shop robotic cells(Elsevier, 2016) Batur, G. D.; Erol, S.; Karasan, O. E.We focus on the scheduling problem arising in hybrid flexible flow shops which repeatedly produce a set of multiple part-types and where the transportation of the parts between the machines is performed by a robot. The cycle time of the cell is affected by the robot move sequence, part/machine assignments and part sequences. In a hybrid flexible flow shop in which there exist one machine in the first and two machines in the second stage, the problem of determining the best cycle time is modeled as a traveling salesman problem. In order to provide a solution methodology for realistic problem instances, a Simulated Annealing based heuristic is constructed and the problem is solved using two different neighborhood structures. The results are also compared against an effective proposed lower bound value.Item Open Access SIMARD: a simulated annealing based RNA design algorithm with quality pre-selection strategies(IEEE, 2017-12) Sav, Sinem; Hampson, D. J. D.; Tsang, H. H.Most of the biological processes including expression levels of genes and translation of DNA to produce proteins within cells depend on RNA sequences, and the structure of the RNA plays vital role for its function. RNA design problem refers to the design of an RNA sequence that folds into given secondary structure. However, vast number of possible nucleotide combinations make this an NP-Hard problem. To solve the RNA design problem, a number of researchers have tried to implement algorithms using local stochastic search, context-free grammars, global sampling or evolutionary programming approaches. In this paper, we examine SIMARD, an RNA design algorithm that implements simulated annealing techniques. We also propose QPS, a mutation operator for SIMARD that pre-selects high quality sequences. Furthermore, we present experiment results of SIMARD compared to eight other RNA design algorithms using the Rfam datset. The experiment results indicate that SIMARD shows promising results in terms of Hamming distance between designed sequence and the target structure, and outperforms ERD in terms of free energy. © 2016 IEEE.Item Open Access Simulated annealing for texture segmentation with Markov models(IEEE, 1989) Yalabık, M. Cemal; Yalabık, N.Binary textured images are segmented into regions of different textures. The binary Markov model is used, and model parameters are assumed to be unknown prior to segmentation. The parameters are estimated using a weighted-least-squares method, while segmentation is performed iteratively using simulated annealing. To speed up the annealing process, an initial coarse segmentation algorithm that quickly determines the approximate region categories using k-means clustering algorithm is used. The results look promising, and the computational costs can be reduced further by optimization of the computations.Item Open Access VLSI circuit partitioning for simulation and placement(Bilkent University, 1993-01) Tahboub, RadwanSimulation time of Very Large Scale Integrated (VLSI) circuits may be improved substantially upon the partitioning of the circuit into several smaller sub-circuits. Node Splitting (NS) is the underlying basis for partitioning of large integrated circuits into several, more manageable, and sometimes similar sub-circuits to enhance computer simulation efficiency. In this thesis, a partitioning scheme based on the NS is used to partition VLSI circuits efficiently. The proposed algorithms will be used as a preprocessing step to increase the efficiency of a VLSI analog circuit simulator designed by the EE Department at Bilkent University. With small modifications, the same algorithms are used to form clusters of transistors based on their interconnections. The clustered circuit will then be partitioned using well known heuristics such as Simulated Annealing and Kernighan-Lin to be used in VLSI placement. The results with this method have been superior to those with the conventional implementations. We have observed a factor of 3-4 speed-up in CPU time, together with 5-10% improvement in the cut size. Experimental results show that the proposed algorithms can be efficiently used in VLSI circuit partitioning for simulation and placement.