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1

Design and validation of a single-jack variable Mach number nozzle in a cryogenic transonic wind tunnel

Yu Chengguo, Zhang Zhili, Wang Ning, Nie Xutao, Peng Qiang, Chen Zhenhua

Journal of Theoretical and Applied Mechanics

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2022

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Vol. 60 nr 4

719--732

EN

The wind tunnel with variable Mach numbers controlled by a single jack is highly desired in the aerospace, automobile and building industry due to its superior controllability and working range. Decreasing the temperature of a test gas is an efficient and economical approach to achieving higher Reynolds numbers that accommodate all working statuses of test subjects, which however, brings new challenges to the wind tunnel design nowadays. This paper proposes a new design concept of a single-jack variable Mach number nozzle based on its particular cryogenic characteristics, as the nozzle is the core structure to achieve variable Mach numbers. The contours of the nozzle under different Reynolds numbers and Mach numbers are modeled and solved by an incomplete elliptic integral, followed by modification with cryogenic characteristics. A 0.3-m cryogenic wind tunnel is utilized as a validation platform for the nozzle design, resulting in designed contours being in line with the measured contours. Moreover, the root means square (RMS) deviations of Mach number 1.3 at the core position are controlled within 0.011 in low and high temperatures, which surpasses the other existing wind tunnels.

2

Application of the Plackett-Burman Design on Soil Fertility Determinants

Mehdaoui Imane, El Ouadrhiri Faiçal, Saoudi Hassani El Mokhtar, Ben Abbou Mohamed, Elhaji Mounia, Akhazane Mohamed, Taleb Mustapha, Rais Zakia

Journal of Ecological Engineering

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2022

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Vol. 23, nr 12

254--263

EN

In the present review article, a soil from the region of Fez-Sefrou Morocco was screened for some physicochemical characteristics using the Plackett-Burman model in order to determine the most important factors that promote its fertility. Five independent variables were selected: pH, electrical conductivity, humidity, organic matter, and C/N ratio. These variables were evaluated by statistical analysis, based on their significance, the value of the coefficient of determination and the Pareto chart. The results suggest that humidity and C/N ratio have an influence with a high level of confidence, while the other three show no significant effect on the content of nutrients in the soil. The analysis of the R2 variance value also showed that the models used for prediction were large and significant factors (p less than 0.05). Pareto chart plots for each response and its characteristics provided accurate data to select well-fitting variables for further optimization.

3

A geomorphodiversity map of the Soutpansberg Range, South Africa

Kori Edmore, Onyango Odhiambo Beneah Daniel, Chikoore Hector

Landform Analysis

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2019

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Vol. 38

13--24

EN

Within the emerging broad science of geodiversity, geomorphological diversity (geomorphodiversity) assesses the form of surface features of a place or region. This paper uses SRTM data and GIS techniques to assess geomorphological diversity of the Soutpansberg range, in Limpopo Province, South Africa. Suitable factors to assess geomorphological diversity were identified as geology, slope position, soil erodibility, landform position, relative heights, insolation, hydrography and ruggedness. Each factor was normalised to five classes by applying natural breaks. All the eight factors were weighted before overlaying. The weighting reveal that respectively, geology, slope and soils carry more weight. Ruggedness, relative height and insolation carry the least weight, in that order. The final geomorphodiversity map reveals that almost half of the Soutpansberg range has high to very high geomorphological diversity. We conclude that factor specific research can add more information to geomorphodiversity research and education.

4

Quantitative assessment of urban transport development – a spatial approach

Czech A., Biezdudnaja A., Lewczuk J., Razumowskij W.

Engineering Management in Production and Services

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2018

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Vol. 10, no. 1

32--44

EN

Urban transport is considered the basis of properly functioning cities and their development. The main aim of the paper is to attempt the assessment of urban transport development in selected voivodeships (provinces) as a crucial factor of macro logistics. The research also aimed to identify the underdeveloped areas of urban transport in Poland as the basis for the implementation of support policy. The source of information in the investigation process was data drawn from the Central Statistical Office in Poland for 2013–2016. In the scope of dealing with the research problem, chosen classical and order multivariate statistical measures were implemented into the research process. Next, the taxonomic measures for the years of interest served as the basis for the construction of the total (general) synthetic measure applicable to the entire period. The main results and findings of the research indicate that the level of urban transport development is correlated with the whole transportation system which affects the socio-economic development of some regions of Poland. The research can lead to a better understanding of Polish urban transportation development in selected regions. Hence, the results can be helpful in the investment process and for shaping the right transportation policy to improve the use of financial resources.

5

Dual mode 4th order active-RC low-pass filter with tunable cut-off frequency from 3 MHz to 20 MHz in 65 nm CMOS

Kiela K., Jurgo M., Navickas R.

Przegląd Elektrotechniczny

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2017

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R. 93, nr 1

263--267

EN

In this paper, a 4th order active-RC filter with two approximation modes and a tunable bandwidth from 3 MHz to 20 MHz is presented. The filter can be configured to achieve maximally flat in-band magnitude or phase response by using a dual mode resistor bank and has gain control. PVT induced parameter drift compensation is accomplished by using a reduced-in-size resistor bank structure made of series and parallel connected resistors. Furthermore, a, design method for the resistor bank is presented, that allows component value calculation based on accuracy and tuning step requirements. The power dissipation is bandwidth depended and ranges from 13 mW to 23 mW from a 1.2 V supply for the entire tuning range, while the SFDR is higher than 72 dB and 65 dB at min and max bandwidth settings respectively. The proposed filter is designed and its parameters verified by using 65 nm CMOS technology and occupy a layout area of 0.172mm2.

PL

W artykule przedstawiony aktywny RC filtr dolnoprzepustowy czwartego rzędu z dwoma trybami aproksymacji i przestrajaną częstotliwością graniczną od 3 MHz do 20 MHz w technologii 65 nm CMOS. Przedstawiono też metodę projektowania zestawu rezystorów, która umożliwia obliczenie wartości składnika w oparciu na wymagania dokładności i kroku regulowania.

6

The power of prediction process in the tests of ammunition elements

Ampuła D.

Journal of KONBiN

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2017

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No. 43

23--48

EN

The author reminds the definition of coefficient determination and the idea of the largest credibility method in the introduction of the article. Firstly, the aspect of new coefficient defined by McFadden as a power of prediction process and called pseudo R2 was characterized. The similar type of R2 coefficients proposed by other known statisticians were described. Moreover, the hierarchic way of building the logistic regress model, through adding next variables to adjust an estimated model to empirical data was introduced. Four kinds of variables were analysed, whose adjustment influence on the estimated logistic regress model was affected by the quantity of inconsistences which appeared in the data result. The calculations of parameter R2 made by the McFadden’s, Nagelkerke’s and Cox-Snell’s formulas were presented. Concise conclusions relating to the estimated logistic regress model on the basis of empirical data from tested MD-8 fuses type were introduced in the end of the article and this model was compared to values of R2 coefficient counted in the article. It was stated, that McFadden’s pseudo R2 parameter is most often used and it defines the power of prediction process.

PL

W artykule scharakteryzowano postać nowego współczynnika określonego przez McFadden-a jako moc procesu predykcji i nazywanego pseudo R2. Przedstawiono praktyczny przykład określania mocy predykcji w oparciu o wybrane dane empiryczne. Zaprezentowano hierarchiczny sposób budowy modelu regresji logistycznej, poprzez dołączanie kolejnych zmiennych w celu dopasowania szacowanego modelu do danych empirycznych. Analizowano cztery rodzaje zmiennych, których wpływ na dopasowanie szacowanego modelu regresji logistycznej był uzależniony od ilości niezgodności jakie wystąpiły w wynikach danych. Przedstawiono obliczenia parametru R2 wykonane za pomocą wzorów McFadden-a, Nagelkerke-a i Cox-Snell-a. Na końcu artykułu przedstawiono zwięzłe wnioski dotyczące oszacowanego modelu regresji logistycznej na podstawie danych empirycznych z badanych zapalników typu MD-8 oraz porównano ten model do obliczonych w artykule wartości współczynnika R2. Stwierdzono, że parametr pseudo R2 McFadden’a jest najczęściej używany i określa on moc procesu predykcji.

7

Regresja jako metoda procesu predykcji

Ampuła D.

Problemy Techniki Uzbrojenia

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2014

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R. 43, z. 130

67--78

PL

W artykule autor we wstępie przedstawia krótki rys historyczny a następnie zapoznaje czytelnika z metodą analizy regresji. Na początku scharakteryzowano funkcję regresji I i II rodzaju po czym na przykładzie podjętych decyzji podiagnostycznych zapalników typu B-23U, przedstawiono sposób wyznaczenia tych funkcji. Scharakteryzowano klasyczny model regresji liniowej oraz za pomocą ww. wyników badań przestawiono postać graficzną i analityczną funkcji regresji łącznie z wyliczonymi przedziałami ufności. Zgodnie z procedurą wyznaczania linii regresji dokonano także estymacji parametrów modelu regresji oraz weryfikacji tego modelu. Zaprezentowano również metodę określania predykcji na podstawie modelu regresji liniowej dla analizowanych w artykule zapalników typu B-23U. Przedstawiono graficzną interpretację przedziału predykcji dla ww. zapalników. Ze względu na obszerność artykułu, nie omówiono testów sprawdzających podczas weryfikacji statystycznej zaprezentowanego modelu regresji. W artykule zastosowano uniwersalne narzędzie statystyczne jakim jest program Statistica. Dzięki niemu przedstawiono interpretację graficzną oraz arkusze wyników analizowanych danych statystycznych zapalników typu B-23U. Na końcu artykułu przedstawiono zwięzłe wnioski dotyczące analizy regresji liniowej.

EN

: In the introduction of the article the author presents a short historical outline and then acquaints the reader with the method of the regress analysis. The function of regress 1st and 2nd kind is shown at the beginning and on the example undertaken after diagnostic decisions fuses type B-23U, the way of marking this function was introduced. The classic model of the linear regress was characterized and using the results of the tests the graphic and analytic figure of the regress function together with enumerate trust range was introduced. According to the procedure of making regress line, the estimation of the parameters regress model and verification of this model was also executed. The method of defining prediction on the basis linear regress model for analysed fuses type B-23U in article was presented. The graphic interpretation of the prediction range for this fuses was discussed. Due to the extensiveness article, tests checking during the statistical verification of the presented regress model were not outlined. In the article, the universal statistical tool was applied i.e. the Statistica programme. Thanks to it, the graphic interpretation and the sheets of analysed statistical results of the fuses type B-23U were introduced. Concise conclusions relating to analyses linear of regress were introduced at the end of the article.

8

Predykcja za pomocą metody najmniejszych kwadratów

Ampuła D.

Problemy Techniki Uzbrojenia

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2014

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R. 43, z. 129

39--48

PL

W artykule autor we wstępie przedstawia rys historyczny, a następnie zapoznaje czytelnika z metodą najmniejszych kwadratów. Na początku zaprezentowano problem wyboru postaci analitycznej modelu, uznając według literatury za priorytet wybór jak najmniej skomplikowaną postać tego modelu. Następnie przedstawiono sposób obliczania procesu predykcji za pomocą modelu analitycznego tej metody, korzystając z ustalonych wzorów. Nie wykonano jednak obliczeń dla przypadku danych statystycznych przedstawionych w tabeli z uwagi na dość skomplikowany sposób ich wyliczenia. Przedstawiono także sposób obliczenia współczynników równania regresji za pomocą oprogramowania Excel. Z uwagi na ograniczone możliwości tego oprogramowania, nie wykonano postaci graficznej uzyskanego równania regresji. W dalszej części zaprezentowano uniwersalne narzędzie statystyczne jakim jest program Statistica. Dzięki niemu przedstawiono metodę interpretacji przedstawionych danych statystycznych za pomocą metody najmniejszych kwadratów w celu uzyskania predykcji tych danych. Pokazano dwa przykładowe wykresy jako rozwiązanie przedstawionego problemu predykcji. Na końcu przedstawiono zwięzłe wnioski dotyczące predykcji za pomocą metody najmniejszych kwadratów.

EN

In the introduction of the article the author presents a historical outline and acquaints the reader with the method of the smallest squares. The problem of choosing the model’s analytic figure is shown at the beginning and according to literature, the priority of the choice as the least complicated figure of this model was adopted. The way of calculation of prediction process was introduced using the analytic model of this method, using settled formulas. However, calculations were not made for cases of statistical data introduced in the table due to difficult way of their calculation. The way of the coefficients calculation of the regress equation using Excel software was also outlined. Because of the limited possibilities of this software, the graphic figure of the received regress equation was not presented. In the further part, the universal statistical tool i.e. the Statistica programme was shown. Thanks to this programme, the method of statistical data interpretations was introduced using the method of the smallest squares in order to obtain the prediction of these data. There were showed two example graphs as the solution introduced of the prediction problem. Concise conclusions relating to prediction using the method of the smallest squares were included at the end of the article.

9

Errors-in-variables for mobile mapping algorithms in the presence of outliers

Schaffrin B., Uzun S.

Archiwum Fotogrametrii, Kartografii i Teledetekcji

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2011

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Vol. 22

377--387

EN

A few years ago, Schaffrin and Iz (2008) generalized the traditional Kalman filter in such a way that it could handle observation equations with errors-in-variables. This approach led to what has since become known as Total Kalman Filtering (TKF). A drawback, however, was that the usual “data snooping” techniques were no longer applicable in the same manner. Therefore, in the presence of outliers, new search techniques need to be devised in order to accommodate for those errors-in-variables with non-zero expectations. In this contribution, an attempt will be described to prepare a suitable algorithm for this purpose in the context of mobile mapping.

10

The method of capacity values determination in human joint gap

Wierzcholski K.

International Journal of Applied Mechanics and Engineering

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2002

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Vol. 7, Spec. is

65-71

EN

Analysis of carrying capacity for synovial unsymmetrical fluid flow in various geometry of human joints is presented in this paper. Following assumptions are taking into account: stationary, isothermal and incompressible synovial unsymmetrical fluid flow in magnetic field, rotational motion of bone head, squeeze of synovial fluid in human joint gap, changeable synovial non-Newtonian fluid viscosity, changeable gap height in human joint, and constant synovial fluid density.

11

Human joints treated by the unsteady magnetic field

Wierzcholski K.

International Journal of Applied Mechanics and Engineering

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2002

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Vol. 7, Spec. is

55-63

EN

Analytical calculations of pressure and velocity components in human hip joint for synovial unsymmetrical fluid flow are presented in this paper. Following assumptions are taking into account: unsteady, isothermal and incompressible synovial unsymmetrical non Newtonian synovial fluid flow, rotational motion of bone head, variable magnetic field and constant synovial fluid density. The method of solutions of hydrodynamic lubrication problem in human hip joint in presence of unsteady magnetic field is presented in this paper.