Wyniki wyszukiwania - BazTech

1

Statistical Optimization of Underwater Lower-Frequency Sound Insulation for Locally Resonant Sonic Material Using Genetic Algorithm

Yuan Bo, Chen Yong, Tan Bilian, Li Bo

Archives of Acoustics

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2019

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Vol. 44, No. 2

365--374

EN

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.

2

Statistical optimization of the synthesis of plant-derived fatty acid esters of TMP over homogeneous organometallic tin catalyst

Nowicki J., Drabik J., Stańczyk D., Mosio-Mosiewski J., Woszczyński P.

Polish Journal of Chemical Technology

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2018

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Vol. 20, nr 2

61--70

EN

A class of very important industrial-grade biolubricants was synthesized from plant-derived fatty acids (oleic and isostearic acid) by direct esterifi cation of trimethylolpropane according to novel effective and high selective method using Sn bis(2-ethylhexanoate) as catalyst. Model transesterifi cation reactions were performed with oleic and isostearic acids to optimize the reaction conditions to obtain maximum content of TMP triesters. Used specifi c homogeneous Sn catalyst allows to obtain TMP esters with very high content of triesters, above of 94 wt% without deep vacuum purifying distillation. Both TMP esters were evaluated for their physicochemical and tribological properties using ASTM standards. Both TMP esters exhibited high viscosity indexes and excellent low temperature properties.

3

Statistical optimization of stress relieving parameters on closed cell aluminium foam using central composite design

Puspitasari D., Ginta T. L., Mustapha M., Sallih A., Puspitasari P.

Archives of Materials Science and Engineering

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2018

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Vol. 89, nr 2

55--63

EN

Purpose: This study concerns about the influence of stress relieving parameters on the hardness of closed cell aluminium foam using central composite design. Design/methodology/approach: The responses of three stress relieving parameters: heating temperature, holding time and stabilization temperature are studied and analysed through 20 experimental runs designed according to central composite design. The results of microhardness test corresponded to the microstructural evaluation of closed-cell aluminium foam using optical microscope. Analysis of Variance (ANOVA) technique is employed to study the significance of each parameter on the microhardness property. In this process the design has five levels for each parameter. The stress relieving process of the samples were performed using a vacuum furnace. The hardness test was conducted using a micro hardness tester LM247AT and the microstructure of the samples were obtained using optical microscopy technique. Findings: It was found that the highest value of hardness of 192.78 HV was obtained when the stress relieving process is set with the following parameters: heating (500°C); holding time (120 min) and stabilization temperature (450°C). Since higher heating temperature and longer holding time produce sample with larger grain size and has an adverse effect on the hardness value. Research limitations/implications: Liquid metal and powder metallurgical processing still produces a non-uniform and poorly reproducible cellular structure. This cellular structure demonstrates poor quality difference on decomposition and melting temperature, called anisotropic early expansion. Originality/value: To improve the poor cellular structure quality, stress relieving method is proposed in this study. Stress relieving method can improve the microstructure of the material.

4

Quasi-offline fair scheduling in third generation wireless data networks

Martyna J.

Journal of Telecommunications and Information Technology

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2013

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nr 3

112--114

EN

In 3G wireless data networks, network operators would like to balance system throughput while serving users fairly. This is achieved through the use of fair scheduling. However, this approach provides non-Pareto optimal bandwidth allocation when considering a network as a whole. In this paper an optimal offline algorithm that is based on the decomposition result for a double stochastic matrix by Birkhoff and von Neumann is proposed. A utility max-min fairness is suggested for the derivation of a double stochastic matrix. Using a numerical experiment, new approach improves the fairness objective and is close to the optimal solution.

5

Wykorzystanie metod statystycznych do określenia optymalnego przekroju żyły powrotnej w sieciach kablowych średniego napięcia

Benesz M., Tarko R.

Zeszyty Naukowe Wydziału Elektrotechniki i Automatyki Politechniki Gdańskiej

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2012

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Nr 31

31-34

PL

W artykule przedstawiono problematykę statystycznej analizy optymalnego przekroju żyły powrotnej w sieciach kablowych, przy uwzględnieniu danych rzeczywistych sieci rozdzielczych o znamionowym napięciu: 6 kV, 15 kV, 20 kV i 30kV. Przedstawiona analiza ma na celu określenie poziomu zagrożenia żył powrotnych kabli średniego napięcia wskutek przekroczenia ich obciążalności prądem zwarciowych. Analizy przekroczeń obciążalności zwarciowej żył powrotnych dokonano przy wykorzystaniu programów: Electromagnetic Transients Program - Alternative Transients Program (EMTP-ATP) oraz Statgraphics, wykorzystanych odpowiednio przy modelowaniu komputerowym zwarć podwójnych oraz przy analizie optymalizacji statystycznej doboru przekroju żyły powrotnej.

EN

This paper presents the problem of statistical analysis of the optimum cross-section of the return conductor, taking into account the actual data of the distribution network. The aim of this study was to determine the level of risk of venous return conductors as a result of exceeding their permissible load short-circuit current. Analysis was made using programs: The Electromagnetic Transients Program - Alternative Transients Program (EMTP-ATP) and Statgraphics, appropriately to computer modeling of double faults and the analysis of statistical optimization.

6

Betony wysokowartościowe - kryteria optymalizacji składu

Prokopski G., Franczyk M.

Budownictwo Ogólne i Konstrukcje Drewniane : zeszyt naukowy

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2008

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Nr 9

61--71

PL

W pracy przedstawiono zasady projektowania składu, a także efekty zastosowania wielokryterialnej optymalizacji statystycznej w analizie wyników badań betonów wysokowartościowych (BWW). Analizę i ocenę badań przeprowadzono w obszarze przyjętego planu doświadczeń. Efektem działań było uzyskanie rozwiązań preferowanych w zakresie składu betonów z uwagi na przyjęte kryteria optymalizacji.

EN

This paper presents the effect of use the mathematics methods optimization to design High Performance Concretes. The analyses and valuation of concretes property have realized in the plan experiences on the basis of 6 criteria optimization. The results of analyses have presented as the preferred solutions of concretes composition.