On the functional complexity of a two-dimensional interval search problem

2002 ◽  
Vol 12 (1) ◽  
Author(s):  
E.E. Gasanov ◽  
I.V. Kuznetsova
Keyword(s):  
Search Time ◽  
Search Problem ◽  
Two Dimensional ◽  
Worst Case ◽  
Logarithmic Average ◽  
Functional Complexity

AbstractWe suggest a modification of the Bentley-Maurer algorithm which solves a twodimensional interval search problem. This modification allows us to decrease the initially logarithmic average search time to constant, retaining the logarithmic worst-case search time. This algorithm depends on a parameter whose change results in variation of the needed memory from Ϭ(k

TWO-DIMENSIONAL RANGE SEARCH BASED ON THE VORONOI DIAGRAM

2005 ◽  
Vol 15 (02) ◽  
pp. 151-166
Author(s):  
TAKESHI KANDA ◽  
KOKICHI SUGIHARA
Keyword(s):  
Voronoi Diagram ◽  
Dimensional Space ◽  
Search Problem ◽  
Two Dimensional ◽  
Worst Case ◽  
Average Case ◽  
Range Search ◽  
Almost All ◽  
Set Of Points ◽  
Dimensional Range

This paper studies the two-dimensional range search problem, and constructs a simple and efficient algorithm based on the Voronoi diagram. In this problem, a set of points and a query range are given, and we want to enumerate all the points which are inside the query range as quickly as possible. In most of the previous researches on this problem, the shape of the query range is restricted to particular ones such as circles, rectangles and triangles, and the improvement on the worst-case performance has been pursued. On the other hand, the algorithm proposed in this paper is designed for a general shape of the query range in the two-dimensional space, and is intended to accomplish a good average-case performance. This performance is actually observed by numerical experiments. In these experiments, we compare the execution time of the proposed algorithm with those of other representative algorithms such as those based on the bucketing technique and the k-d tree. We can observe that our algorithm shows the better performance in almost all the cases.

scholarly journals Multi-Tier Heterogeneous Beam Management for Future Indoor FSO Networks

2021 ◽  
Vol 11 (8) ◽  
pp. 3627
Author(s):  
Michael B. Rahaim ◽  
Thomas D. C. Little ◽  
Mona Hella
Keyword(s):  
Management Strategy ◽  
Beam Steering ◽  
Search Time ◽  
Search Space ◽  
Analysis Framework ◽  
Free Space Optical ◽  
Optimization Analysis ◽  
Worst Case ◽  
Available Bandwidth ◽  
Space Optical Communication

To meet the growing demand for wireless capacity, communications in the Terahertz (THz) and optical bands are being broadly explored. Communications within these bands provide massive bandwidth potential along with highly directional beam steering capabilities. While the available bandwidth offers incredible link capacity, the directionality of these technologies offers an even more significant potential for spatial capacity or area spectral efficiency. However, this directionality also implies a challenge related to the network’s ability to quickly establish a connection. In this paper, we introduce a multi-tier heterogeneous (MTH) beamform management strategy that utilizes various wireless technologies in order to quickly acquire a highly directional indoor free space optical communication (FSO) link. The multi-tier design offers the high resolution of indoor FSO while the millimeter-wave (mmWave) system narrows the FSO search space. By narrowing the search space, the system relaxes the requirements of the FSO network in order to assure a practical search time. This paper introduces the necessary components of the proposed beam management strategy and provides a foundational analysis framework to demonstrate the relative impact of coverage, resolution, and steering velocity across tiers. Furthermore, an optimization analysis is used to define the top tier resolution that minimizes worst-case search time as a function of lower tier resolution and top tier range.

Robust Flutter Analysis of an Airfoil with Flap Freeplay Uncertainty

2008 ◽  
Vol 33-37 ◽  
pp. 1247-1252 ◽  
Author(s):  
Zhi Chun Yang ◽  
Ying Song Gu
Keyword(s):  
Control Surface ◽  
Two Dimensional ◽  
Advanced Technique ◽  
Worst Case ◽  
Wing Model ◽  
Freeplay Nonlinearity ◽  
Flutter Analysis ◽  
Flutter Boundary ◽  
Nominal Parameter ◽  
Flutter Margin

Modern robust flutter method is an advanced technique for flutter margin estimation. It always gives the worst-case flutter speed with respect to potential modeling errors. Most literatures are focused on linear parameter uncertainty in mass, stiffness and damping parameters, etc. But the uncertainties of some structural nonlinear parameters, the freeplay in control surface for example, have not been taken into account. A robust flutter analysis approach in μ-framework with uncertain nonlinear operator is proposed in this study. Using describing function method the equivalent stiffness formulation is derived for a two dimensional wing model with freeplay nonlinearity in its flap rotating stiffness. The robust flutter margin is calculated for the two dimensional wing with flap freeplay uncertainty and the results are compared with that obtained with nominal parameter values. It is found that by considering the perturbation of freeplay parameter more conservative flutter boundary can be obtained, and the proposed method in μ-framework can be applied in flutter analysis with other types of concentrated nonlinearities.

scholarly journals Multipurpose self-configuration of programmable photonic circuits

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Daniel Pérez-López ◽  
Aitor López ◽  
Prometheus DasMahapatra ◽  
José Capmany
Keyword(s):  
Signal Processing ◽  
High Speed ◽  
Two Dimensional ◽  
Photonic Circuits ◽  
Computational Optimization ◽  
Digital Electronics ◽  
Control Signals ◽  
Integration Density ◽  
Functional Complexity ◽  
Multiple Configuration

AbstractProgrammable integrated photonic circuits have been called upon to lead a new revolution in information systems by teaming up with high speed digital electronics and in this way, adding unique complementary features supported by their ability to provide bandwidth-unconstrained analog signal processing. Relying on a common hardware implemented by two-dimensional integrated photonic waveguide meshes, they can provide multiple functionalities by suitable programming of their control signals. Scalability, which is essential for increasing functional complexity and integration density, is currently limited by the need to precisely control and configure several hundreds of variables and simultaneously manage multiple configuration actions. Here we propose and experimentally demonstrate two different approaches towards management automation in programmable integrated photonic circuits. These enable the simultaneous handling of circuit self-characterization, auto-routing, self-configuration and optimization. By combining computational optimization and photonics, this work takes an important step towards the realization of high-density and complex integrated programmable photonics.

scholarly journals OceanMesh2D 1.0: MATLAB-based software for two-dimensional unstructured mesh generation in coastal ocean modeling

2019 ◽  
Vol 12 (5) ◽  
pp. 1847-1868 ◽  
Author(s):  
Keith J. Roberts ◽  
William J. Pringle ◽  
Joannes J. Westerink
Keyword(s):  
Ocean Circulation ◽  
Mesh Generation ◽  
Mesh Size ◽  
Unstructured Meshes ◽  
Coastal Ocean ◽  
Ocean Modeling ◽  
Force Balance ◽  
Generation Process ◽  
Two Dimensional ◽  
Worst Case

Abstract. OceanMesh2D is a set of MATLAB functions with preprocessing and post-processing utilities to generate two-dimensional (2-D) unstructured meshes for coastal ocean circulation models. Mesh resolution is controlled according to a variety of feature-driven geometric and topo-bathymetric functions. Mesh generation is achieved through a force balance algorithm to locate vertices and a number of topological improvement strategies aimed at improving the worst-case triangle quality. The placement of vertices along the mesh boundary is adapted automatically according to the mesh size function, eliminating the need for contour simplification algorithms. The software expresses the mesh design and generation process via an objected-oriented framework that facilitates efficient workflows that are flexible and automatic. This paper illustrates the various capabilities of the software and demonstrates its utility in realistic applications by producing high-quality, multiscale, unstructured meshes.

Study of interface reactions between Ti/Al/Ni/Au metallization and AlGaN/GaN heterostructures

Open Physics ◽  
2013 ◽  
Vol 11 (2) ◽  
Author(s):  
Wojciech Macherzyński ◽  
Bogdan Paszkiewicz
Keyword(s):  
Solid State ◽  
Structural Changes ◽  
Electron Gas ◽  
Solid State Reactions ◽  
Two Dimensional ◽  
Dimensional Electron ◽  
Two Dimensional Electron Gas ◽  
Metallic Contact ◽  
Worst Case ◽  
Dimensional Electron Gas

AbstractThe electrical characteristics, and the range of interface metal-semiconductor reactions of Ti/Al/Ni/Au metallization with AlGaN/GaN heterostructures at various annealing temperatures ranging from 715°C to 865°C, have been investigated. The relation between the depth of the interface solid state reaction and the current-voltage (I-V) characteristics of the ohmic contact, have been studied. It was observed, that the transition from nonlinear to linear I-V behaviour occurred after the annealing at 805°C. The structural changes in AlGaN/GaN heterostructures beneath the metallic contact after the thermal treatment, were investigated. After removing the metallization by etching, the atomic force microscope profiles and scanning electron microscope images, were studied to define the depth to which the interfacial solid state reactions between the metallization and the semiconductor structure take place. It was observed, that the changes in the heterostructures, caused by the interface m-s reactions, were observed up to a depth of 180 nm at 865°C. In the worst case, this could result in the complete removal of the two-dimensional electron gas under the metallization of the ohmic contacts. To study the influence of the annealing process parameters on the properties of the two-dimensional electron gas, the van der Pauw Hall mobility measurement was performed.

scholarly journals Anytime Heuristic Search

2007 ◽  
Vol 28 ◽  
pp. 267-297 ◽  
Author(s):  
E. A. Hansen ◽  
R. Zhou
Keyword(s):  
Heuristic Search ◽  
Search Algorithm ◽  
Search Time ◽  
Optimal Solution ◽  
Search Problem ◽  
A Algorithm ◽  
Solution Quality ◽  
Multiple Sequence ◽  
Anytime Algorithm ◽  
Heuristic Search Algorithm

We describe how to convert the heuristic search algorithm A* into an anytime algorithm that finds a sequence of improved solutions and eventually converges to an optimal solution. The approach we adopt uses weighted heuristic search to find an approximate solution quickly, and then continues the weighted search to find improved solutions as well as to improve a bound on the suboptimality of the current solution. When the time available to solve a search problem is limited or uncertain, this creates an anytime heuristic search algorithm that allows a flexible tradeoff between search time and solution quality. We analyze the properties of the resulting Anytime A* algorithm, and consider its performance in three domains; sliding-tile puzzles, STRIPS planning, and multiple sequence alignment. To illustrate the generality of this approach, we also describe how to transform the memory-efficient search algorithm Recursive Best-First Search (RBFS) into an anytime algorithm.

scholarly journals Worst-case & average-case Efficiency trade-offs for search problems

2021 ◽  
Author(s):  
Preeti Sharma
Keyword(s):  
Search Problem ◽  
Worst Case ◽  
Evacuation Time ◽  
Average Case ◽  
Deterministic Algorithms ◽  
Trade Offs ◽  
Time Work ◽  
Research Problems ◽  
Work Done ◽  
Vast Area

Evacuation problems fall under the vast area of search theory and operations research. Problems of evacuation of two robots on a unit disc have been studied for an efficient evacuation time. Work done so far has focused on improving the ’worst-case’ evacuation time with deterministic algorithms. We study the ’average-case’ evacuation time (randomized algorithms) while considering the efficiency trade-off between worst-case and average-case costs. Our other contribution is to analyze average-case and worst-case costs for the cowpath problem (another search problem) which helped us to set a parallel method for the evacuation problem.

A Novel Rule-Based Method for Individualized Spot Welding Sequence Optimization With Respect to Geometrical Quality

2019 ◽  
Vol 141 (11) ◽  
Author(s):  
Roham Sadeghi Tabar ◽  
Kristina Wärmefjord ◽  
Rikard Söderberg ◽  
Lars Lindkvist
Keyword(s):  
Genetic Algorithm ◽  
Sheet Metal ◽  
Spot Welding ◽  
Search Time ◽  
Search Problem ◽  
Optimization Approach ◽  
Hamiltonian Graph ◽  
Rule Based ◽  
Geometrical Quality ◽  
Welding Sequence

Abstract Spot welding is the predominant joining process for the sheet metal assemblies. The assemblies, during this process, are mainly bent and deformed. These deformations, along with the single part variations, are the primary sources of the aesthetic and functional geometrical problems in an assembly. The sequence of welding has a considerable effect on the geometrical variation of the final assembly. Finding the optimal weld sequence for the geometrical quality can be categorized as a combinatorial Hamiltonian graph search problem. Exhaustive search to find the optimum, using the finite element method simulations in the computer-aided tolerancing tools, is a time-consuming and thereby infeasible task. Applying the genetic algorithm to this problem can considerably reduce the search time, but finding the global optimum is not guaranteed, and still, a large number of sequences need to be evaluated. The effectiveness of these types of algorithms is dependent on the quality of the initial solutions. Previous studies have attempted to solve this problem by random initiation of the population in the genetic algorithm. In this paper, a rule-based approach for initiating the genetic algorithm for spot weld sequencing is introduced. The optimization approach is applied to three automotive sheet metal assemblies for evaluation. The results show that the proposed method improves the computation time and effectiveness of the genetic algorithm.

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