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Number of results: 86
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Abstract

In this paper, the applications of the multivariate data analysis and optimization on vibration signals from compressors have been tested on the assembly line to identify nonconforming products. The multivariate analysis has wide applicability in the optimization of weather forecasting, agricultural experiments, or, as in this case study, in quality control. The techniques of discriminant analysis and linear program were used to solve the problem. The acceleration and velocity signals used in this work were measured in twenty-five rotating compressors, of which eleven were classified as good baseline compressors and fourteen with manufacturing defects by the specialists in the final acoustic test of the production line. The results obtained with the discriminant analysis separated the conforming and nonconforming groups with a significance level of 0.01, which validated the proposed methodology.
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Abstract

A transformer is an important part of power transmission and transformation equipment. Once a fault occurs, it may cause a large-scale power outage. The safety of the transformer is related to the safe and stable operation of the power system. Aiming at the problem that the diagnosis result of transformer fault diagnosis method is not ideal and the model is unstable, a transformer fault diagnosis model based on improved particle swarm optimization online sequence extreme learning machine (IPSO-OS-ELM) algorithm is proposed. The improved particle swarmoptimization algorithm is applied to the transformer fault diagnosis model based on the OS-ELM, and the problems of randomly selecting parameters in the hidden layer of the OS-ELM and its network output not stable enough, are solved by optimization. Finally, the effectiveness of the improved fault diagnosis model in improving the accuracy is verified by simulation experiments.
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Abstract

In the last decade, Poland has become one of the most active markets for unconventional hydrocarbon deposits exploration. At present, there are twenty concessions for the exploration and/or discovery of reserves, including shale gas. The area covered by exploration concessions constitutes ca. 7.5% of the country’s area. Four main stages can be distinguished In the shale gas development and exploitation project: the selection and preparation of the place of development of the wells, hydraulic drilling and fracturing, exploitation (production) and marketing, exploitation suppression and land reclamation. In the paper, the concept of cost analysis of an investment project related to the exploration and development of a shale gas field/area was presented. The first two stages related to the preparatory work, carried out on the selected site, as well as drilling and hydraulic fracturing were analyzed. For economic reasons, the only rational way to make shale gas reserves available is to use horizontal drilling, either singly or in groups. The number of drilling pads covering the concession area is a fundamental determinant of the development cost of the deposit. In the paper, the results of the cost analysis of various types of reaming method with an area of 25,000,000 m2 were presented. Cost estimates were prepared for two variants: group drilling for three types of drilling pads: with three, five and seven wells and for single wells. The results show that, as the number of horizontal wells increases, the total cost of the development of the deposit is reduced. For tree-wells pad, these costs are 7% lower than in the second variant, for five-well pads they are 11% lower, and for seven-well pads they are 11.5% smaller than in the second variant. Authors, using applied methodology, indicate the direction of further research that will enable the optimization of shale gas drilling operations.
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Abstract

Transport is one of the factors influencing the development of metropolitan areas. However, for its efficient work, numerous optimizations are required. Main tasks are shortening travel time, improving service quality and increasing the number of passengers served. The author has presented current studies on the field in optimization of public transport, mainly ways to optimize the transport network construction, based on large data sets about the population and their communication behaviour. Methods of combining various types of public transport with each other are presented. In the paper also are presents authors studies on the communication accessibility within the city of Cracow. Estimated distances from buildings to various types of public transport stops. The results were presented in aggregated form. Calculated communication speed of three types of public transport functioning in Cracow has also been discussed.
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Abstract

This article considers designing of a renewable electrical power generation system for self-contained homes away from conventional grids. A model based on a technique for the analysis and evaluation of two solar and wind energy sources, electrochemical storage and charging of a housing area is introduced into a simulation and calculation program that aims to decide, based on the optimized results, on electrical energy production system coupled or separated from the two sources mentioned above that must be able to ensure a continuous energy balance at any time of the day. Such system is the most cost-effective among the systems found. The wind system adopted in the study is of the low starting speed that meets the criteria of low winds in the selected region under study unlike the adequate solar resource, which will lead to an examination of its feasibility and profitability to compensate for the inactivity of photovoltaic panels in periods of no sunlight. That is a system with fewer photovoltaic panels and storage batteries whereby these should return a full day of autonomy. Two configurations are selected and discussed. The first is composed of photovoltaic panels and storage batteries and the other includes the addition of a wind system in combination with the photovoltaic system with storage but at a higher investment cost than the first. Consequently, this result proves that is preferable to opt for a purely photovoltaic system supported by the storage in this type of site and invalidates the interest of adding micro wind turbines adapted to sites with low wind resources.
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Abstract

The locally resonant sonic material (LRSM) is an artificial metamaterial that can block underwater sound. The low-frequency insulation performance of LRSM can be enhanced by coupling local resonance and Bragg scattering effects. However, such method is hard to be experimentally proven as the best optimizing method. Hence, this paper proposes a statistical optimization method, which first finds a group of optimal solutions of an object function by utilizing genetic algorithm multiple times, and then analyzes the distribution of the fitness and the Euclidean distance of the obtained solutions, in order to verify whether the result is the global optimum. By using this method, we obtain the global optimal solution of the low-frequency insulation of LRSM. By varying parameters of the optimum, it can be found that the optimized insulation performance of the LRSM is contributed by the coupling of local resonance with Bragg scattering effect, as well as a distinct impedance mismatch between the matrix of LRSM and the surrounding water. This indicates coupling different effects with impedance mismatches is the best method to enhance the low-frequency insulation performance of LRSM.
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Abstract

Hybrid Renewable Energy Systems connected to the traditional power suppliers are an interesting technological solution in the field of energy engineering and the integration of renewable systems with other energy systems can significantly increase in energy reliability. In this paper, an analysis and optimization of the hybrid energy system, which uses photovoltaic modules and wind turbines components connected to the grid, is presented. The system components are optimized using two objectives criteria: economic and environmental. The optimization has been performed based on the experimental data acquired for the whole year. Results showed the optimal configuration for the hybrid system based on economical objective, that presents the best compromise between the number of components and total efficiency. This achieved the lowest cost of energy but with relatively high CO2 emissions, while environmental objective results with lower CO2 emissions and higher cost of energy and presents the best compromise between the number of components and system net present cost. It has been shown that a hybrid system can be optimized in such a way that CO2 emission is maximally reduced and – separately – in terms of reducing the cost. However, the study shows that these two criteria cannot be optimized at the same time. Reducing the system cost increase CO2 emission and enhancing ecological effect makes the system cost larger. However, depends on strategies, a balance between different optimization criteria can be found. Regardless of the strategy used economic criteria – which also indirect takes environmental aspects as a cost of penalties – should be considered as a major criterion of optimization while the other objectives including environmental objectives are less important.
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Abstract

Games are among problems that can be reduced to optimization, for which one of the most universal and productive solving method is a heuristic approach. In this article we present results of benchmark tests on using 5 heuristic methods to solve a physical model of the darts game. Discussion of the scores and conclusions from the research have shown that application of heuristic methods can simulate artificial intelligence as a regular player with very good results.
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Abstract

The problem that this paper investigates, namely, optimization of overlay computing systems, follows naturally from growing need for effective processing and consequently, fast development of various distributed systems. We consider an overlay-based computing system, i.e., a virtual computing system is deployed on the top of an existing physical network (e.g., Internet) providing connectivity between computing nodes. The main motivation behind the overlay concept is simple provision of network functionalities (e.g., diversity, flexibility, manageability) in a relatively cost-effective way as well as regardless of physical and logical structure of underlying networks. The workflow of tasks processed in the computing system assumes that there are many sources of input data and many destinations of output data, i.e., many-to-many transmissions are used in the system. The addressed optimization problem is formulatedin the form of an ILP (Integer Linear Programing) model. Since the model is computationally demanding and NP-complete, besides the branch-and-bound algorithm included in the CPLEX solver, we propose additional cut inequalities. Moreover, we present and test two effective heuristic algorithms: tabu search and greedy. Both methods yield satisfactory results close to optimal.
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Abstract

The 802.11ax standard final specification is expected in 2019, however first parameters are just released. The target of the new standard is four times improvement of the average throughput within the given area. This standard is dedicated for usage in dense environment such as stadiums, means of municipal communication, conference halls and others. The main target is to support many users at the same time with the single access point. The question arises if the new standard will have higher throughput then previous ones in the single user mode. The author calculated the maximal theoretical throughput of the 802.11ax standard and compared the results with the throughput of older 802.11 standards such as 802.11n and 802.11ac. The new he-wifi-network example included in the ns-3.27 release of the NS-3 simulator was used to simulate the throughput between the access point and the user terminal. The results indicate that in some conditions the 802.11ac standard has higher throughput than the new 802.11ax standard.
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Abstract

Within the boundaries of many municipal urbanized areas, large grounds are found, from which the noise is emitted into the environment, surrounded by the regions liable to acoustic protection. Such a condition generates many problems including also those ones related to the lack of the fulfillment of requirements concerning environmental protection against excessive noise. Therefore the aim of vital importance is the proper management of municipal grounds, both in view of the investment in policy steering, especially of new investments, and in the case of activities aimed at maintaining or restoring (revitalizing) the acoustic properties on the grounds that have already been used or simply degraded before. Keeping the scale of the problem in mind, such activities must be carried on not temporarily, but must have a systemic character. The structure of every system is characterized by the appropriate relationships among their elements and the properties of those relationships. In case of the noise management system, the elements of such a system are the activities connected with the management itself that are the actions which rely on specifying the aims and causing their realization within the scope and on the grounds subject to the managing entity. The superior aim of such activities should be to supply the tools for improvement of management and in the process of taking decisions that relate to investments including the of optimization conditions and maintenance of socio-economic importance of such areas.
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Abstract

This paper presents the idea of increasing the effectiveness of slag decopperisation in an electric furnace in the "Głogów II" Copper Smelter by replacing the currently added CaCO3with a less energy-intensive technological additive. As a result of this conversion, one may expect improved parameters of the process, including process time or power consumption per cycle. The incentives to optimize the process are the benefits of increasing copper production in the company and the growing global demand for this metal. The paper also describes other factors that may have a significant impact on the optimization of the copper production process. Based on the literature analysis, a solution has been developed that improves the copper production process. The benefits of using a new technology additive primarily include increased share of copper in the alloy, reduced production costs, reduced amount of power consumed per cycle and reduced time it takes to melt. At the conclusion of the paper, the issues raised are highlighted, stressing that mastering the slag slurry process in electric furnaces requires continuous improvement.
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Abstract

A simulation-based optimization approach to design of phase excitation tapers for linear phased antenna arrays is presented. The design optimization process is accelerated by means of Surrogate-Based Optimization (SBO); it uses a coarse-mesh surrogate of the array element for adjusting the array’s active reflection coefficient responses and a fast surrogate of the antenna array radiation pattern. The primary optimization objective is to minimize side-lobes in the principal plane of the radiation pattern while scanning the main beam. The optimization outcome is a set of element phase excitation tapers versus the scan angle. The design objectives are evaluated at the high fidelity level of description using simulations of the discrete electromagnetic model of the entire array so that the effects of element coupling and other possible interaction within the array structure are accounted for. At the same time, the optimization process is fast due to SBO. Performance and numerical cost of the approach are demonstrated by optimizing a 16-element linear array of microstrip antennas. Experimental verification has been carried out for a manufactured prototype of the optimized array. It demonstrates good agreement between the radiation patterns obtained from simulations and from physical measurements (the latter constructed through superposition of the measured element patterns).
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Abstract

In this work, response surface optimization strategy was employed to enhance the biodegradation process of fresh palm oil mill effluent (POME) by Aspergillus niger and Trichoderma virens. A central composite design (CCD) combined with response surface methodology (RSM) were employed to study the effects of three independent variables: inoculum size (%), agitation rate (rpm) and temperature (°C) on the biodegradation processes and production of biosolids enriched with fungal biomass protein. The results achieved using A. niger were compared to those obtained using T. virens. The optimal conditions for the biodegradation processes in terms of total suspended solids (TSS), turbidity, chemical oxygen demand (COD), specific resistance to filtration (SRF) and production of biosolids enriched with fungal biomass protein in fresh POME treated with A. niger and T. virens have been predicted by multiple response optimization and verified experimentally at 19% (v/v) inoculum size, 100 rpm, 30.2°C and 5% (v/v) inoculum size, 100 rpm, 33.3°C respectively. As disclosed by ANOVA and response surface plots, the effects of inoculum size and agitation rate on fresh POME treatment process by both fungal strains were significant.
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Abstract

Geometric parameters of a ribbon impeller were optimized on the basis of numerical calculations obtained from the solution of our own 3D/2D hybrid model. The optimization was made taking into account mixing power and homogenization time for ribbon impellers with a different number of ribbons and width operating in a laminar motion for Newtonian fluid. Due to minimum mixing energy required to stir a unit volume of liquid the most efficient impeller appeared to be that with one ribbon of width equal to 0.1 to 0.15 of the mixing vessel diameter. Impellers with more than one ribbon needed much higher mixing power but did not increase significantly secondary circulation in the vessel. These impellers increased first of all primary circulation, i.e. they increased only circular motion of liquid in the vessel.
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Abstract

This paper presents a methodology for contact detection between convex quadric surfaces using its implicit equations. With some small modifications in the equations, one can model superellipsoids, superhyperboloids of one or two sheets and supertoroids. This methodology is to be implemented on a multibody dynamics code, in order to simulate the interpenetration between mechanical systems, particularly, the simulation of collisions with motor vehicles and other road users, such as cars, motorcycles and pedestrians. The contact detection of two bodies is formulated as a convex nonlinear constrained optimization problem that is solved using two methods, an Interior Point method (IP) and a Sequential Quadratic Programming method (SQP), coded in MATLAB and FORTRAN environment, respectively. The objective function to be minimized is the distance between both surfaces. The design constraints are the implicit superquadrics surfaces equations and operations between its normal vectors and the distance itself. The contact points or the points that minimize the distance between the surfaces are the design variables. Computational efficiency can be improved by using Bounding Volumes in contact detection pre-steps. First one approximate the geometry using spheres, and then Oriented Bounding Boxes (OBB). Results show that the optimization technique suits for the accurate contact detection between objects modelled by implicit superquadric equations.
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Abstract

This paper compares selected optimization-based methods for the analysis of multibody systems with redundant constraints. The following numerical schemes are examined: direct integration method, Udwadia-Kalaba formulation, two types of least-squares block solution method and Udwadia-Phohomsiri formulation. In order to compare efficiency of the algorithms, a series of simulations is performed on two exemplary McPherson struts. In the first variant, the mechanism has no redundant constraints whereas the other is overconstrained. Three constraint stabilization schemes are also compared in terms of integration errors.
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Abstract

New measurement technologies, e.g. Light Detection And Ranging (LiDAR), generate very large datasets. In many cases, it is reasonable to reduce the number of measuring points, but in such a way that the datasets after reduction satisfy specific optimization criteria. For this purpose the Optimum Dataset (OptD) method proposed in [1] and [2] can be applied. The OptD method with the use of several optimization criteria is called OptD-multi and it gives several acceptable solutions. The paper presents methods of selecting one best solution based on the assumptions of two selected numerical optimization methods: the weighted sum method and the "-constraint method. The research was carried out on two measurement datasets from Airborne Laser Scanning (ALS) and Mobile Laser Scanning (MLS). The analysis have shown that it is possible to use numerical optimization methods (often used in construction) to obtain the LiDAR data. Both methods gave different results, they are determined by initially adopted assumptions and – in relation to early made findings, these results can be used instead of the original dataset for various studies.
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Abstract

The box wing system is an unconventional way to connect the lifting surfaces that the designers willingly to use in prototypes of new aircrafts. The article present a way to quickly optimize the wing structure of box wing airplane that can be useful during conceptual design. At the beginning, there is presented theory and methods used to code optimization program. Structure analysis is based on FEM beam model, which is sufficient in conceptual design. Optimization is performed using hybrid method, connection of simple iteration and gradient descent methods. Finally, the program is validated by case study.
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