Wyniki wyszukiwania - BazTech

1

Stan badań nad laserami kaskadowymi na zakres średniej podczerwieni w ITE

Bugajski M., Sobczak G., Pierścińska D., Michalak K., Gutowski P., Janus K., Pierściński K., Branas J., Kuzmicz A., Chmielewski K., Sankowska I.

Przegląd Elektrotechniczny

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2018

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R. 94, nr 8

35--38

PL

W artykule omówione zostaną paramery laserów kaskadowych wutwarzanych w Instytucie Technologii Elektronowej. Wskazane zostaną obszary w których lasery wytwarzane w kraju mogą konkurowac z podobnymi przyrządami wytwarzanymi za granicą.

EN

The paper describes the status of technology of mid-IR quantum cascade lasers (QCLs) based on GaAs/AlGaAs and InAlAs/InGaAs/InP material system developed at the Institute of Electron Technology. Two main types of lasers were investigated. First, was based on lattice matched active region designed for wavelengths of λ=9.0 μm-10.0 μm. The second, was based on strain-compensated active region designed for wavelengths of λ=4.5 μm-5.5 μm. Basic characteristics and parameters of all types of lasers are discussed. Possible applications in which the lasers developed at ITE can compete with those available on world market are indicated.

2

Wpływ temperatury czynnika suszącego na kinetykę suszenia kropel soku z buraków ćwikłowych

Peroń S., Michalak K., Surma M.

Inżynieria Rolnicza

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2010

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R. 14, nr 2

111-116

PL

Na stanowisku laboratoryjnym przeprowadzono doświadczenia nad suszeniem pojedynczych kropel koncentratu soku z buraków ćwikłowych o zawartości ekstraktu 30% przy temperaturach czynnika suszącego 50, 60, 70, 80, 90°C oraz jego stałej prędkości v=1m*s-1. Wpływ temperatury czynnika suszącego na spadek zawartości wody opisano równaniem wykładniczym. Określono też wielkość strumienia wilgoci.

EN

A laboratory setup was used to carry out experiments on drying single drops of garden beet juice concentrate with extract content of 30% for drying medium temperatures: 50, 60, 70, 80, 90°C, and its constant velocity v=1m*s-1. The impact of drying medium temperature on content drop.

3

Leki przeciw grypie. Synteza tamiflu® - leku gromadzonego, aby zapobiec epidemii ptasiej grypy

Karchier M., Michalak K., Wicha J.

Wiadomości Chemiczne

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2007

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[Z] 61, 1-2

7-42

EN

Influenza (flu) and related viral infections present a constant threat to public health. World-wide efforts have been recently initiated (coordinated by WHO) to prevent global epidemic in view of spreading deadly bird flu virus (H5N1) among people. Attention has been focused on Tamiflu® (1, Figure 1), synthetic, orally active drug manufactured by Hoffmann - La Roche On the surface of the flu virus there are located two proteins important for infecting animal cell: hemagglutinin and neuraminidase (sialidase). Hemagglutinin is responsible for the recognition of specific sialic acids in the cell membrane glycoconjugates; neuraminidase is involved in subsequent hydrolysis of sialic acid residue and is crucial for the virus propagation. Sialic acids are sugar-related keto-acids, as neuraminic acid 2. Their structure is specific for a given species. Functions of hemagglutinin or neuraminidase have been targeted in systematic search for anti-flu drugs. The first efficient neuraminidase competitive inhibitor Relanza® (Zanamivir) has been obtained as a mimic of hypothetic oxonium ion involved in sialic acid hydrolysis. Many structures related to Zanamivir have been investigated]. The most successful line of research has been aimed at synthesis of carbocyclic neuraminic acid derivatives from (-)-quinic or (-)-shikimic acids. The Gilead-Roche "first generation" analogue with the double bond oriented toward the hydroxy-group 33 proved more active than its counterpart 34. Further modification of the structure 33 was based on X-ray analysis of protein - inhibitor complexes and led to Tamiflu®. Prime synthesis of Tamiflu® from (-)-shikimic acid involved several steps. Since this starting material is rather expensive more economic approaches have been studied. The technological approach to the key epoxide 75 from (-)-quinic acid involves bicyclic lactone 70 controlled dehydration to form 73 and regiospecific acetal reduction using borane-dimethylsulfide complex in the presence of a silylating agent. Use of the developed methods and shikimic acid as the starting material allowed for an efficient access to the target epoxide 75. The epoxide 75 has been transformed into the final product in several steps. Most advanced synthetic routes transforming 75 into Tamiflu® rely upon the use of tert-butylamine and then diallylamine. Current studies on transformation of glucose into shikimic acid by genetically modified strain of Escherichia coli are likely to secure supplies of this convenient starting material for Tamiflu® production. E. J. Corey et al. have developed enantioselective total synthesis of Tamiflu®. [2+4] cycloaddition reaction of butadiene and trifluoroethylacrylate in the presence of a chiral oxazoborolidine catalyst provided cyclohex-3-enecarboxylic acid derivative (87, Scheme 19). Transformation of 87 into 99 embraced several steps, including the novel haloamidation (86 into 97). The synthesis route involved 12 steps and afforded Tamiflu® in 25% overall yield. Catalytic enantioselective reaction of the easily accessible meso-aziridine 101with trimethylsilylazide provided the cornerstone to total synthesis of Tamiflu® by M. Shibasaki et al. [48]. The synthetic route from azide 102 to the target involved several steps (Schemes 23 and 24). Among them the efficient allylic oxidation of 109 and the nickel-catalyzed conjugate addition of trimethylsilylcyanide to ?,?-unsaturated ketone 110 that contribute to general synthetic methodology. In the synthesis developed by Cong i Yao [51], the starting material - serine-derived aldehyde 117 (Garner's aldehyde, Scheme 25) has been selected from the "chiral pool". The synthesis involves a sequence of diastereoselective reactions and the ring-closure metathesis reaction (130 into 131) using the II generation Grubbs catalyst. Approaches to Tamiflu® illustrate the impressive achievements of organic synthesis. However, at present the high cost of this drug may hamper its broader application.

4

Dynamic Correlation Approach to Early Stopping in Neural Forecasting of Macroeconomic Indices

Michalak K., Raciborski R.

Journal of Applied Computer Science

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2007

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Vol. 15, nr 2

27-40

EN

Neural networks are commonly used for modelling he behaviour of macroeconomic indices. One of the issues that arise in neural networks applications is that when a neural network is trained for too long the quality of the predictions tends to drop with the increasing number of training iterations. To overcome this problem various methods of early stopping are employed. In this paper an early stopping method based on dynamic correlation between time series introduced in our previous work is validated on macroeconomic indices. In correlation-based approach the decision whether to stop training or not is based on the prediction error value calculated for the time series that has possibly the lowest mean dynamic correlation with the time series being predicted. Experimental results show advantages of dynamic correlation method in predicting the behaviour of industrial production indices for EU-25 member countries. Experiments show that correlation-based method produces lower forecast errors compared to the early stopping performed using a subset of historical samples from the same time series. The results obtained imply that this observation is of a high statistical significance.

5

Correlation-based feature selection strategy in classification problems

Michalak K., Kwaśnicka H.

International Journal of Applied Mathematics and Computer Science

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2006

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Vol. 16, no 4

503-511

EN

In classification problems, the issue of high dimensionality, of data is often considered important. To lower data dimensionality, feature selection methods are often employed. To select a set of features that will span a representation space that is as good as possible for the classification task, one must take into consideration possible interdependencies between the features. As a trade-off between the complexity of the selection process and the quality of the selected feature set, a pairwise selection strategy has been recently suggested. In this paper, a modified pairwise selection strategy is proposed. Our research suggests that computation time can be significantly lowered while maintaining the quality of the selected feature sets by using mixed univariate and bivariate feature evaluation based on the correlation between the features. This paper presents the comparison of the performance of our method with that of the unmodified pairwise selection strategy based on several well-known benchmark sets. Experimental results show that, in most cases, it is possible to lower computation time and that with high statistical significance the quality of the selected feature sets is not lower compared with those selected using the unmodified pairwise selection process.

6

Trialkylsilyl Triflates-Practical Diastereoselective Catalysts in Conjugate Addition Reaction of Silyl Ketene Acetals and alfa, beta-Unsaturated Ketones

Michalak K., Wicha J.

Polish Journal of Chemistry

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2004

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Vol. 78 / nr 2

205-215

EN

Catalytic effect of trimethylsilyl triflate (TMSOTf) or tert-butyldimethylsilyl triflate (TBSOTf) in conjugate addition reaction of the respective trialkylsilyl derivatives of thioester enolates (silyl ketene acetals) 2a-2e and _,_-unsaturated ketones 1a-1c has been studied. It was shown that silyl triflates are efficient catalysts with stereochemical profile similar to that of trityl hexachloroantimonate. The use of silyl triflates is particularly advantageous in tandem reactions involving conjugate addition as the first step.

7

Zastosowanie technologii informatycznej w projektowaniu systemów człowiek-obiekt techniczny

Michalak K., Ragin-Skorecka K.

Zeszyty Naukowe Politechniki Poznańskiej. Organizacja i Zarządzanie

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2002

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Nr 34

99--108

PL

W artykule przedstawiono zasady wykorzystania wiedzy ergonomicznej w projektowaniu urządzeń technicznych. Konieczność uzupełnienia wiedzy technicznej wiedzą ergonomiczną powoduje zmiany metodologiczne w projektowaniu. Projektowanie ergonomiczne wymaga użycia specyficznych kryteriów decyzyjnych zawierających wiedzę o człowieku. Aby wiedzę tę przybliżyć projektantom i konstruktorom maszyn, opracowano komputerowy program wspomagający podejmowanie decyzji projektowych poprawnych z punktu widzenia wymagań ergonomii.

EN

In the paper are shown the principles of applying of ergonomic knowledge to designing of technical equipment. The necessity of supplement of technical knowledge with ergonomic knowledge causes methodological changes in designing. Ergonomic designing requires use of specific decisional criterions including the knowledge about the human. In order to bring it closer to designers and machine constructors, the computer program was worked out to aid to take designed decisions, which are correct of ergonomic point of view.

8

Clustal W algorithm for multiple sequence alignment revisited

Błażewicz J., Formanowicz P., Kasprzak M., Michalak K., Wierzejewski P.

Foundations of Computing and Decision Sciences

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2001

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Vol. 26, No. 3

189-196

EN

Multiple sequence alignment is one of the most important problems arising in DNA and protein recognition. Clustal W is a well known and practically [ applied method used for solving the problem. In the paper, a modification of the algorithm is described which shortens considerably its mean running time. The modification uses graphs of partial alignments and operations on resulting semi-cliques. As shown by an extensive computational experiment running time is reduced up to 50%, as compared with the original approach.

9

Borland visual dbase 7.0 nowoczesne środowisko do tworzenia aplikacji bazodanowych.

Mazur H., Michalak K.

Prace Naukowe Wydziałowego Zakładu Informatyki Politechniki Wrocławskiej

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2000

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z. 1

97-104

PL

Artykuł omawia nowe elementy systemu Borland Visual dBASE 7.0 w stosunku do poprzednich wersji systemów dBASE. Zwraca uwagę na zalety i wady nowego systemu. Borland Visual dBASE 7.0 umożliwia zaawansowane programowanie zorientowane obiektowo przy czym dane są przechowywane w tabelach (zgodnie z modelem relacyjnym).

EN

The paper presents Borland Visual dBASE 7.0. Visual dBASE offers dozens of new features and language elements to provide you with a more productive, efficient work environment. This article describes the major enhancements.