ON THE ACCELERATION OF OPTIMIZATION METHODS FOR THE PROBLEM OF SYNTHESIS OF MULTILAYER OPTICAL COATINGS

Five ways to speed up the multidimensional search in order to solve the problem of synthesis of multilayer optical coatings by using the methods of zero and first orders have been considered. The first way is to use an analytical derivative for the target quality function of the multilayer coating. It allows us to calculate accurately (within the computer arithmetic) the value of the gradient of a smooth objective function and generalized gradient of a non-smooth objective one. The first way requires the same number of arithmetic operations as well as finite-difference methods of calculating the gradient and the generalized gradient. The second way is to use a speedy finding of the objective function gradient using the prefix- and suffix-arrays in the analytical method of calculating the gradient. This technique allows us to reduce the number of arithmetic operations thrice for large-scale problems. The third way is the use of tabulating the values of trigonometric functions to calculate the characteristic matrices. This technique reduces the execution time of multiplication operations of characteristic matrices ten times depending on the computer’s specifications. For some computer architectures, this advantage is more than 140 times. The fourth method is the use of the golden section method for the one-dimensional optimization in the problems of synthesis of optical coatings. In particular, when solving one partial problem it is shown that the ternary search method requires approximately 40% more time than the golden section method. The fifth way is to use the effective implementation of multiplication of two matrices. It lies in changing the order of the second and third cycles for the well-known method of multiplying two matrices and fixing in a common variable value of the element of the first matrix. This allows us to speed up significantly the multiplication operation of two matrices. For matrices having 1000 x 1000 dimension the acceleration is from 2 to 15 times, depending on the computer's specifications.

Testing Performance (Time Analysis) of Nearest Neighbour (NN) Search Algorithms on K-d Trees

K-d tree (k-dimensional tree) is a space partitioning data structure for organizing points in a k-dimensional space. K-d tree, or Multidimensional Binary Search Tree is a useful data structure for several applications such as searches involving a multidimensional search key (e.g., Range Search and Nearest Neighbour Search). K-d trees are a special case of binary space partitioning trees.KNN Search is a searching algorithm with complexity O(N log N) {N= no. of data points}. This search algorithm is relatively better than brute force search {Complexity= O(n*k); where k=No. of neighbours searched, N=No. of Data Points in Kd tree} for dimensions N>>2D {N=No. of Points, D=Dimensionality of Tree}.Furthermore, Parallel KNN Search is much more efficient and performs better than KNN Search, as it harnesses parallel processing capabilities of computers and thus, results in better search time.This paper tests the time performance of KNN Search and Parallel KNN Search and compares them by plotting it on a 3D graph. A more comprehensive comparison is done by use of 2D graphs for each dimension(from 2 to 20).

Identifying the Locations of Atmospheric Pollution Point Source by Using a Hybrid Particle Swarm Optimization

This research aims to improve the particle swarm optimization (PSO) algorithm by combining a multidimensional search with a line search to determine the location of the air pollution point sources and their respective emission rates. Both multidimensional search and line search do not require the derivative of the cost function. By exploring a symmetric property of search domain, this innovative search tool incorporating a multidimensional search and line search in the PSO is referred to as the hybrid PSO (HPSO). Measuring the pollutant concentration emanating from the pollution point sources through the aid of sensors represents the first stage in the process of evaluating the efficiency of HPSO. The summation of the square of the differences between the observed concentration and the concentration that is theoretically expected (inverse Gaussian plume model or numerical estimations) is used as a cost function. All experiments in this research are therefore conducted using the HPSO sensing technique. To effectively identify air pollution point sources as well as calculate emission rates, optimum positioning of sensors must also be determined. Moreover, the frame of discussion of this research also involves a detailed comparison of the results obtained by the PSO algorithm, the GA (genetic algorithm) and the HPSO algorithm in terms of single pollutant location detection, respectively. In the case of multiple sources, only the findings based on PSO and HPSO algorithms are taken into consideration. This research eventually verifies and confirms that the HPSO does offer substantially better performance in the measuring of pollutant locations as well as emission rates of the air pollution point sources than the original PSO.

ON THE USE OF HEURISTIC ALGORITHMS IN THE PROBLEMS OF OPTIMAL PARAMET-RIC SYNTHESIS

The problem of optimal synthesis of engineering systems is considered, with due account for the ran-dom changes in their production and operational parameters. A number of ways and means of creating effective heuristic algorithms for multidimensional search optimization are proposed to solve the emerging problems. The paper focuses on the bat algorithm and the creation of its parallel modifica-tion.

Creation of the electronic archive of the first President of the Republic of Uzbekistan

The article discusses some aspects of the organization of the information system of the Archive of the First President of the Republic of Uzbekistan Islam Karimov. The problem of digitalization of archival activities is quite relevant for Uzbekistan due to the fact that traditional approaches to the construction of information retrieval mechanisms and the organization of information services in archiving today often do not correspond to the required level of efficiency and user needs. As part of the work carried out, the specific task was to organize a software environment for the formation of an electronic catalog of archived descriptions, filling databases of digitized copies of archival materials, as well as flexible multidimensional search and presentation of information. The way to solve this problem is to use the archival information system «AtoM». As a result, a database of digitized archival materials was created, reflecting the life and work of the First President of the Republic of Uzbekistan Islam Karimov, equipped with a developed search and reference apparatus.

COMPARING STEREO IMAGE MATCHING PERFORMANCE BY MULTIDIMENSIONAL SEARCH WINDOWS

<p><strong>Abstract.</strong> Image matching is a key technology for extraction of dense point cloud and 3D terrain information using satellite/aerial imagery. In image matching using brightness values of pixels, the size of search window is an important factor for determining the matching performance. In this study, we perform matching using multi-dimensional search windows applicable to area-based matching and compare the performance. Also, the search window is reconfigured by using the linear information existing on the image, and the matching is tried. Comparing the fixed search window and the multi-window matching results, it was confirmed that the multiple windows under the same conditions show relatively high accuracy. We can also see that the method of applying the line element has slightly better accuracy. As a result of applying the line element extraction technique, a large number of pixels are not extracted compared with the total image pixel amount. There was no significant difference in the results of visual analysis. However, we have confirmed that this technique has contributed to improving accuracy.</p>

Multiple Parameters Estimation of BOC Signal in Multipath Environment

For the multiple parameters estimation of BOC signal at the low SNR and multipath environment, the method which applies the characteristics of cyclic spectrum is developed. Firstly, the cyclic spectrum function of multipath BOC signal is derived. Then the cyclostationary property of BOC signal is analyzed. Finally, a novel parameter estimation algorithm of BOC signal, which makes use of the position of cyclic spectral peaks to estimate the carrier frequency, the subcarrier rate and PN code rate, is present. In the experiment the time-domain smoothing method is used to calculate the cyclic spectrum of BOC signal when the frequency is equal to zero in order to avoid the multidimensional search. At the same time using the method of the cumulative average can increase the SNR margin of the algorithm. Simulation results show that the multiple parameters of multipath BOC signal can be estimated effectively and the estimation performance is associated with the multipath environment.

Multidimensional Ontology-Based Information Retrieval for Academic Counseling

Conventional information retrieval can only locate documents containing user specified keywords. Integrating domain ontology with information retrieval extends the keyword-based search to semantic search and thus potentially improves the precision and recall of the document retrieval. In this paper, a set of new multidimensional ontology-based information retrieval algorithms is proposed for searching both specific and related terms. In particular, the relevant data properties of an instance, the relevant concepts, the relevant related concepts, and the related instances of a given user query can be identified from the domain ontology via the multidimensional search. Using the proposed algorithms, an intelligent counselling system which provides 24x7 online academic counselling services is developed. Through an interactive user-interface and domain ontology, the system facilitates students to find desired information by reviewing and refining their query. The article also outlines how to enable ontology-based searching for a conventional website.