Wyniki wyszukiwania - BazTech

1

Methodology for the Composite Tire Numerical Simulation Based on the Frequency Response Analysis

Karpenko Mykola, Skačkauskas Paulius, Prentkovskis Olegas

Eksploatacja i Niezawodność

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2023

|

Vol. 25, no. 2

art. no. 163289

EN

Reliability and maintenance analysis in transport focus on the main objective of accident and incident investigations that benefit to better understanding of the causes of accidents and prevention of them in the future. The conducted research presents theoretical and experimental research on composite pneumatic tire used in transport engineering. The approach of the numerical simulation sequence which is offered in this research facilitates engineers in efficient determination of the dynamic properties and behaviour of vehicle tire at design stage. The tire materials have been tested by employing piezoelectric micro-vibration tests and frequency analyses. The Finite Element Method used for numerical simulation in combination with experimental measurements based on optimization by material frequency response, was applied in modelling tire material behaviour avoiding problems of composite structure modelling. The obtained results indicate that the offered methodology can be used in numerical simulation of composite tire investigation and considering material viscos-elastic properties.

2

Analysis of the single stage cycloidal gearbox with lobe defects. Fault diagnosis attempts using coherence function and Morris minimum-bandwidth wavelets

Król Roman

Archive of Mechanical Engineering

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2023

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LXX, nr 3

409--431

EN

In this article, the frequency characteristics of the forces and torques in the various cycloidal gearbox designs were investigated. The aim of the article is the search for frequency patterns that could be used in the formulation of a fault diagnosis methodology. Numerical analysis was performed in the cycloidal gearbox without defects as well as in cycloidal gearboxes with lobe defects or with removed lobes. The results of the numerical analysis were obtained in the multibody dynamics model of the cycloidal gearbox, implemented in Fortran and using the 2nd-order Runge-Kutta method for the integration of the motion equations. The used model is planar and uses Hunt and Crossley’s nonlinear contact modelling algorithm, which was modified using the Heaviside function and backlash to fit cycloidal gearbox model convergence demands. In the analysis of fault diagnosis methods, the coherence function and Morris minimum-bandwidth wavelets were used. It is difficult to find a unique pattern in the results to use in the fault diagnosis because of the random characteristics of the torques at the input and output shafts. Based on obtained results, a promising, low-vibration cycloidal gearbox design with removed 7 lobes of the single wheel was studied using the FFT algorithm.

3

Importance of seismic wave frequency in FEM-based dynamic stress and displacement calculations of the earth slope

Fuławka Krzysztof, Kwietniak Anna, Lay Vera, Jaśkiewicz-Proć Izabela

Studia Geotechnica et Mechanica

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2022

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Vol. 44, nr 1

82--96

EN

Reliable assessment of earthen dams' stability and tailing storage facilities widely used in the mining industry is challenging, particularly under seismic load conditions. In this paper, we propose to take into account the effect of the dominant frequency of seismic load on the stability assessment of tailing/earthen dams. The calculations are performed by finite element modelling (FEM) with the Mohr–Coulomb failure criteria. To separate the frequency content from other dynamic parameters describing the seismic wave, synthetic waveforms with identical amplitude and attenuation characteristics, but differing spectral characteristics have been used. The analysis has been performed for three different slope angles and two scenarios of seismic wave propagation. Consequently, the changes of total displacement and shear stresses depending on the frequencies have been determined and clearly show that lower frequencies cause higher stress levels and displacement. Finally, the response surface methodology has been applied to determine how different parameters affect the slope stability under dynamic load conditions. Overall, this study is a first step to improve the existing methods to assess slope stability when considering seismic load.

4

Monitoring of helicopter swash-plate wear using the FAM-C diagnosis method

Gębura Andrzej, Kowalczyk Henryk, Tokarski Tomasz, Handzel Kacper, Klimaszewski Sławomir Jerzy, Zgrzywa Franciszek

Diagnostyka

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2022

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Vol. 23, No. 1

art. no. 2022104

EN

Helicopter rotor dynamics (blade vibrations, ground resonance, influence of forward speed, etc.) play an important role in the wear and tear of the transmission system and power unit. Particularly fast wear of these components is to be expected in military helicopters in combat conditions, where the flight dynamics parameters are often exceeded. The FAM-C method developed at the Air Force Institute of Technology in Poland has been used to assess and monitor this wear. This method can be used to monitor damage to helicopter propulsion and transmission, where other "classical" methods are less effective due to a very complicated system of forces, variable as to the direction of amplitude and frequency, causing vibrations in closely spaced kinematic pairs. For this reason, vibroacoustic and thermal effects are created around these kinematic pairs, which interfere with each other. In a helicopter, the propulsion unit, including the power transmission unit, is at the same time the carrier unit. This has forced designers to construct a propulsion system with a much greater number of joints and bearing supports. This article presents the possibilities of the FAM-C method for monitoring of swash-plate main bearing wear. The swash-plates are not formally part of the helicopter's propulsion unit but are used to direct the thrust vector of the blades i.e., they direct the helicopter's power vector. Since during this process their components are observable by the FAM-C method, the authors found it necessary to include issues related to their diagnosis in this study. In the FAM-C method, the signal from the AC generator during the normal operation of the helicopter is processed. Analysis of this signal allows simultaneous monitoring of multiple engine and transmission components simultaneously. It does not require any separate sensors for this purpose - one "full-time" alternator or tachometer generator is - with proper collection and processing of the output voltage signal - the source of a whole range of diagnostic information. Thus, one generator is an observer of the technical condition of many elements of the power unit simultaneously. What's more, the signal can be collected from any place in the electrical network, which makes it possible to install the measuring system in safe locations, even while the power train is running. Some examples of diagnostic symptoms leading to wear detection are described. Research based on analysis of these findings with the use of the FAM-C method is described in the paper. In the FAM-C method, signal from the AC generator used in routine operation of the helicopter is processed. Signal analysis enables simultaneous monitoring of several engine and transmission elements. Some examples of diagnostic symptoms used to detect wear are described in the paper.

5

Investigations on an influence of the material properties on vibrations of active rocker-bogie suspension

Sokół Krzysztof, Pierzgalski Maciej

Bulletin of the Polish Academy of Sciences. Technical Sciences

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2022

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Vol. 70, nr 1

art. no. e138239

EN

Unmanned vehicles are often used in everyday life, mostly by rescue teams or scientists exploring new terrains. In those constructions, the suspension has constant dimensions, which leads to many disadvantages and limits the application area. The solution to these problems can be creating a six-wheeled mobile platform that can dynamically change the wheelbase in relation to the area of action or terrain inclination angle. The active change in location of the center of gravity gives a possibility to access sloppy obstacles not available with classical suspensions. The main scope of this study is to investigate the influence of material properties on vibration frequency at different lengths of suspension members. The obtained results will allow finding the optimum material for producing a prototype unit.

6

Analysis of center of pressure displacements and head movements triggered by a visual stimulus created using the virtual reality technology

Wodarski Piotr, Jurkojć Jacek, Chmura Marta, Gruszka Grzegorz, Gzik Marek

Acta of Bioengineering and Biomechanics

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2022

|

Vol. 24, no. 1

20--28

EN

The purpose of the study was to determine how a stimulus presented in the virtual reality environment as a simulation of a fall off the stairs, triggers a loss of balance. The study also examined if the head movement measurements and the analysis in the frequency domain could increase the range of interpretation. Methods: 11 healthy individuals were tested, two [A1] were identified as more susceptible to the introduced disturbance, and one reported having dizziness, car sickness and fear of heights. Measurements of center of pressure (COP) and head positions were performed in the real and in the virtual environment. The beginning of the simulation was either unexpected or preceded by a signal. The analysis included standard parameters determined in time domain as well as the amplitude of the first harmonic from the fast Fourier transform (FFT). Results: The analysis did not reveal statistically significant differences between results obtained: in real and virtual environments, with and without the warning signal. It was possible to notice the effect of virtual disturbance in the three selected individuals; this was particularly evident in the analysis of the first harmonic of the FFT. Conclusions: The conducted tests revealed that the limitation of the analyses exclusively to the time domain could be insufficient for a comprehensive interpretation. The effect of introduced disturbance was particularly noticeable in the analysis of the first harmonic for head movement. The application of this parameter could enable a more accurate investigation of a strategy aimed at maintaining balance.

7

Assessment of the Change in the Tin Concentration in Bronzes to the Basic Components of the Sound of Bells

Cekus Dawid, Nadolski Maciej

Archives of Metallurgy and Materials

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2021

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Vol. 66, iss. 2

531--535

EN

The subject of the study was to determine the impact of changes in mechanical properties of high-tin bronzes on the basic components of the sound of a bell. Change in the tin concentration in the range of about 7.5 to 20 parts wt. in a casting alloy significantly affects the mechanical properties of the alloy such as Young’s modulus or hardness. The free vibrations of bells were obtained with the help of the finite element method. In the numerical analyses the mechanical properties of standard alloys were adopted. The obtained natural frequencies of the bell made of a bronze with different tin concentration in copper were compared with the acoustic properties of a real bell casted on the basis of the same ribs. A significant effect of the increase in the alloying share of tin on the obtained results was stated. In addition, the acoustic analysis of aluminum bronze C95500 have been performed. Based on the obtained results, authors stated that this material can replace the commonly used high tin bronze C91300 for the unit production of bells.

8

Free vibration analysis of imperfect functionally graded sandwich plates: analytical and experimental investigation

Njim E.K., Bakhy S.H., Al-Waily M.

Archives of Materials Science and Engineering

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2021

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Vol. 111, nr 2

49--65

EN

Purpose: This paper develops a new analytical solution to conduct the free vibration analysis of porous functionally graded (FG) sandwich plates based on classical plate theory (CPT). The sandwich plate made of the FGM core consists of one porous metal that had not previously been taken into account in vibration analysis and two homogenous skins. Design/methodology/approach: The analytical formulations were generated based on the classical plate theory (CPT). According to the power law, the material properties of FG plates are expected to vary along the thickness direction of the constituents. Findings: The results show that the porosity parameter and the power gradient parameter significantly influence vibration characteristics. It is found that there is an acceptable error between the analytical and numerical solutions with a maximum discrepancy of 0.576 % at a slenderness ratio (a/h =100), while the maximum error percentage between the analytical and experimental results was found not exceeding 15%. Research limitations/implications: The accuracy of analytical solutions is verified by the adaptive finite elements method (FEM) with commercial ANSYS 2020 R2 software. Practical implications: Free vibration experiments on 3D-printed FGM plates bonded with two thin solid face sheets at the top and bottom surfaces were conducted. Originality/value: The novel sandwich plate consists of one porous polymer core and two homogenous skins which can be widely applied in various fields of aircraft structures, biomedical engineering, and defense technology. This paper presents an analytical and experimental study to investigate the free vibration problem of a functionally graded simply supported rectangular sandwich plate with porosities. The objective of the current work is to examine the effects of some key parameters, such as porous ratio, power-law index, and slenderness ratio, on the natural frequencies and damping characteristics.

9

Wykorzystanie zaawansowanych metod przetwarzania sygnałów do analizy infradźwięków generowanych przez turbiny wiatrowe dużej mocy

Boczar Tomasz, Zmarzły Dariusz, Kozioł Michał, Wotzka Daria

Przegląd Elektrotechniczny

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2020

|

R. 96, nr 6

68--75

PL

W artykule zostaną przedstawione wyniki pomiarów i analizy sygnałów infradźwiękowych emitowanych pracą turbiny wiatrowej o mocy znamionowej 2 MW. Pomiary zostały przeprowadzone jednocześnie w trzech punktach pomiarowych, których odległość od turbiny wynosiła ok. 100 m. Analizy zostaną przeprowadzone przy wykorzystaniu przekształceń częstotliwościowych i analizy korelacyjnej dla pomiarów wykonanych przy zmiennych warunkach metrologicznych.

EN

The article will present the results of measurements and analysis of infrasound signals emitted by a wind turbine of rated power of 2 MW. The measurements were carried out simultaneously in three measurement points, of which the distance to the turbine was about 100 m. The analyses will be carried out with the use of frequency and correlation, for measurements obtained with variable meteorological conditions.

10

Planning of the experiment for the defining of the technical state of the transformer by using amplitude-frequency characteristic

Rubanenko Oleksandr, Grishchuk Maksim, Rubanenko Olena

Przegląd Elektrotechniczny

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2020

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R. 96, nr 3

118--124

EN

The article analyzes existing methods of diagnosing power transformers (PTs). The technique of experiment planning using D-optimal plans is investigated. According to the results of the study, a D-optimal plan of the frequency response measurements was created, which defines the algorithm of the studies. On the example of PT type TMG 1000/10 it is determined that 13 measurements are required to evaluate the condition of the PT during the interpretation of the results of the frequency response measurements. The method of determining the average frequency characteristic of PT is given. This amplitude-frequency characteristic can be used to check the PT status and to detect damage at an early stage of their development.

PL

Artykuł analizuje istniejące metody diagnozowania transformatorów mocy (TM). Badana jest technika planowania eksperymentu z wykorzystaniem planów optymalnych. Zgodnie z wynikami badań opracowano optymalny D-plan pomiarów odpowiedzi częstotliwościowej, który określa algorytm badań. Na przykładzie TM typu TMG 1000/10 ustalono, że do oceny stanu TM podczas interpretacji wyników pomiarów odpowiedzi częstotliwościowej potrzeba 13 pomiarów. Podano metodę wyznaczania charakterystyki średniej częstotliwości TM. Ta charakterystyka amplitudowo-częstotliwościowa może być u żywana do sprawdzania stanu TM i wykrywania uszkodzeń na wczesnym etapie ich rozwoju.

11

Monitoring of electric arc furnace supply voltage frequency using phasor analysis

Barczentewicz Szymon, Duda Krzysztof, Bień Andrzej

Przegląd Elektrotechniczny

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2020

|

R. 96, nr 5

51--54

EN

This paper presents the results of measurement experiment conducted in the operating steel plant. Frequency analysis of measured signals revealed an interesting phenomenon, as it happened that after switching off the electric arc furnace, the frequency of the supplying voltage and current increased slightly instead of decreasing, as we would normally expect. This abnormal frequency behaviour was identified by phasor analysis and also confirmed by the DTFT (Discrete Time Fourier Transform) analysis, and the MatrixPencil analysis.

PL

Artykuł prezentuje wyniki eksperymentu wykonanego w hucie stali. Analiza częstotliwości ujawniła ciekawe zjawisko, w którym po wyłączeniu pieca łukowego częstotliwości napięcia i prądu w wewnętrznej części huty zmniejszyła się zamiast zwiększyć, jak można by się spodziewać. To nieoczekiwane zjawisko zostało zarejestrowane z pomocą PMU i potwierdzone przez transformację Fouriera dla sygnałów dyskretnych oraz analizę MatrixPencil.

12

Analiza wpływu czynników zewnętrznych na wyniki pomiarów infradźwięków emitowanych przez turbiny wiatrowe

Boczar Tomasz, Zmarzły Dariusz, Kozioł Michał, Wotzka Daria

Przegląd Elektrotechniczny

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2020

|

R. 96, nr 7

113--120

PL

W artykule przedstawiono wyniki pomiarów i analiz sygnałów niskiej częstotliwości w zakresie od 1 do 10 kHz zarejestrowanych w farmie wiatrowej na południu Polski. W skład elektrowni wchodziło 15 turbin każda o mocy 2,05 MW. W części wynikowej artykułu zostaną przedstawione zależności ilustrujące wpływ zmian prędkości wiatru, a także odległości między punktami rejestracji a turbiną wiatrową na uzyskiwane zależności częstotliwościowe i czasowo-częstotliwościowe.

EN

The The paper presents the results of measurements and analyses of low frequency signals in the range from 1 to 10 kHz recorded in a wind farm in southern Poland. The power plant consisted of 15 turbines each with a capacity of 2,05 MW. In the resulting part of the article the dependencies illustrating the influence of wind speed changes and also distances between the recording stations and the wind turbine on the obtained frequency and time-frequency relationships will be presented.

13

Analysis of the influence of current frequency on the thermal field of the insulated busbar

Gołębiowski J., Zaręba M.

Bulletin of the Polish Academy of Sciences. Technical Sciences

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2020

|

Vol. 68, nr 1

89--97

EN

The paper analysed the influence of current frequency on the thermal field of the insulated busbar. Its physical model consists of two hollow cylinders and a solid cylinder with different material properties. In turn, the mathematical model is a system of heat conduction equations with the appropriate set of the boundary, initial and continuity conditions. The problem was solved using the modified Green’s method. As a result, the following characteristics and parameters of the busbar were determined as a functions of frequency: heating curves, local time constants, steady-state current ratings, and stationary temperature profiles. The results were positively verified by finite element method.

14

An Overview of the Noise Levels Measured in Industrial Facilities in Serbia and Implemented Methods of Protection

Luburić Uranija Kozmidis, Samardžić Selena, Lakatoš Robert, Mihailović Aleksandra, Veselinović Milka

Archives of Acoustics

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2020

|

Vol. 45, No. 3

499--510

EN

Noise is one of the most significant factors which not only disturbs working conditions, but has a large impact on workers’ health. This problem has existed in industries since the beginning and, despite technical and other solutions, it has not been solved. There is a large number of papers, supported with very detailed analyses, that investigate noise levels in industry or contain questionnaires about the impact of noise on workers’ overall health and work abilities. The purpose of this paper is to contribute to the global picture of sustainability and the development of strategies for improving the quality of working environment, with special attention to the generation of noise in different production processes in thirteen different industries in Novi Sad, Serbia. The paper also seeks to examine the advantages and drawbacks of the implemented protective methods and to provide some recommendations for their better implementation in order to contribute to solving this significant problem of today.

15

Monitorowanie częstotliwości pieca łukowego wykorzystujące technikę fazorową

Barczentewicz Szymon, Duda Krzysztof, Bień Andrzej

Zeszyty Naukowe Wydziału Elektrotechniki i Automatyki Politechniki Gdańskiej

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2019

|

Nr 67

115--118

PL

Artykuł prezentuje wyniki eksperymentu wykonanego w hucie stali. System pomiarowy wykorzystany do przeprowadzenia pomiarów jest oparty na systemie czasu rzeczywistego z układem FPGA, który pozwala na wykonanie pomiarów sygnałów analogowych. Trzy fazy napięcia i prądu zostały zmierzone w trzech wybranych punktach sieci zasilającej. Analiza częstotliwości ujawniła ciekawe zjawisko, w którym po wyłączeniu pieca łukowego częstotliwości napięcia i prądu w wewnętrznej części huty zmniejszyła się zamiast zwiększyć, jak można by się spodziewać. To nieoczekiwane zjawisko zostało zarejestrowane z pomocą PMU i potwierdzone przez analizę MatrixPencil. Przeprowadzone pomiary potwierdziły zasadność monitorowania częstotliwości napięcia zasilania pieców łukowych za pomocą analizy fazora.

EN

This paper presents the results of measurement experiment conducted in the operating steel plant. The measurement system was built with real time system with FPGA module, capable of measuring analog signals. Three phase voltages and currents were acquired in three selected points of supplying power network. Frequency analysis of measured signals revealed an interesting phenomenon, as it happened that after switching off the electric arc furnace, the frequency of the supplying voltage and current increased slightly instead of decreasing, as we would normally expect. This abnormal frequency behavior was identified by phasor analysis and also confirmed by DTFT (Discrete Time Fourier Transform) analysis, and MatrixPencil analysis. Performed measurements proved phasor analysis to be a useful application for electric arc furnace frequency monitoring.

16

The diagnostics of the emergency modes of the variablefrequency electric drive of the pumping complex

Zagirnyak Mykhaylo, Manko Roman, Korenkova Tetyana

Przegląd Elektrotechniczny

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2019

|

R. 95, nr 2

104--107

EN

The paper deals with the demonstration of the fact that the emergency modes that occur in the pipeline networks are accompanied by wave processes resulting in the variation of all parameters of the hydrosystem. We worked out the mathematical model of the automatic control system with the function of the pressure stabilization at the consumer. We obtained the curves representing the alteration of the dynamic processes in the pumping complex during emergency modes occurrence. We formulated the diagnostic signs and proposed the algorithm of the determination of the emergency modes.

PL

W artykule wskazano na fakt, iż tryby awaryjne występujące w sieci rurociągowej związane są z procesami falowymi wynikłym ze zmiany wszystkich parametrów hydrosystemu. Opracowany został model matematyczny systemu sterowania automatycznego z funkcją stabilizacji ciśnienia u odbiorcy. Otrzymano krzywe, reprezentujące zmienność procesów dynamicznych w układzie pompowania podczas wystąpienia trybów awaryjnych. Sformułowane zostały oznaczenia diagnostyczne oraz opracowano algorytm określający tryby awaryjne.

17

Pomiary drgań metalowej płyty ze stopu Hastelloy X

Strąk D., Mięsikowska M., Piasecka M., Michalski D.

Zeszyty Naukowe Wydziału Elektrotechniki i Automatyki Politechniki Gdańskiej

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2018

|

Nr 59

183--186

PL

Celem artykułu jest pomiar drgań metalowej płyty ze stopu Hastelloy X i ich analiza. Badania przeprowadzono z wykorzystaniem wzbudnika magnetycznego własnej konstrukcji oraz wibrometru laserowego PSV-500. Wprowadzenie płyty w drgania o różnej częstotliwości ma na celu wytworzenie sytuacji fizycznej podobnej do występującej na powierzchni grzejnej wymiennika ciepła. W pracy przedstawiono konstrukcję stanowiska badawczego i metodykę przeprowadzenia eksperymentów. Zarejestrowane sygnały analizowano w dziedzinie czasu i częstotliwości.

EN

The aim of this article is to measure vibrations of a metal plate of Hastelloy X alloy and its analysis. The research was performed using a magnetic inductor of authors design and a laser vibrometer PSV-500. The introduction of the plate into vibrations of different frequencies is aimed at creating a physical situation similar to that occurring on the heating surface of the heat exchanger. The work presents the construction of the test stand and the methodology of performing the experiments. The recorded signals were analyzed in terms of time and frequency domain.

18

Wybrane aspekty praktyczne modelowania i prognozowania rozwoju przestępczości

Wawrzyniak Z. M., Borowik G., Pytlak R., Cichosz P.

Przegląd Telekomunikacyjny + Wiadomości Telekomunikacyjne

|

2018

|

nr 11

880--886

PL

Liczba przestępstw, ich lokalizacja, powtarzalność, sezonowość, korelacja z czynnikami pogodowymi i możliwe prognozy to czynniki, które mogą pomagać Policji i administracji publicznej w dostosowaniu strategii planowania i interweniowania. Jednak rozwój wiedzy w jej obszarach aplikacyjnych, w tym także kryminalistyki i kryminologii, zależy głównie od sposobu tworzenia i przekazywania użytecznej informacji. W organizacjach Policji i organów ścigania wielu państw funkcjonuje duża liczba zautomatyzowanych systemów zarządzania. Metody predykcyjne w technikach policyjnych są obecnie szeroko stosowane i na ich podstawie organy ścigania rutynowo podejmują decyzje operacyjne. Celem tego artykułu jest przedstawienie zagadnień związanych z prognozowaniem w odniesieniu do procesu analizy wyników obserwacji, symulacji i przewidywań rozwoju wybranych przestępstw. W szczególności przedstawiono analizę przestępstw komunikacyjnych, kradzieży oraz interwencji policyjnych. Głównym eksperymentem było przeprowadzenie analizy częstotliwościowej zdarzeń oraz zbadanie relacji z atrybutami przestępczości i pogodowymi. Zarówno w przypadku interwencji policyjnych, jak i przestępstw komunikacyjnych można zauważyć wzrost natężenia zdarzeń co siedem dni. W przypadku kradzieży można stwierdzić, iż zdarzenia występują głównie na początku tygodnia, a większość z nich wystąpiła pomiędzy godzinami 10 i 15. Temperatura jest podstawowym czynnikiem pogodowym związanym z występowaniem aktów przemocy i innych przestępstw. Wyniki badań mogą być przydatne do modelowania i prognozowania użycia sił i środków policyjnych w celu skutecznego zapobiegania i zwalczania przestępczości.

EN

Considering the number of crimes, their location, repeatability, seasonality, correlation with weather factors, and possible forecasts, all these factors can help the police and public administration in adjusting the planning and intervening strategies. However, the development of knowledge in its application areas, including forensic science and criminology, depends mainly on the method of creating and transferring useful information. In police and law enforcement agencies, many countries use automated management systems. Prediction methods utilized in police techniques are now widely used, and on their basis, law enforcement agencies routinely make operational decisions. The purpose of this paper is to present issues related to forecasting in relation to the process of analyzing the results of observations, simulations, and forecasts for the development of selected crimes. In particular, the analysis of the communication crime, theft, and police intervention are presented. The key experiment was to perform frequency analysis of events and to investigate the relationship with criminal and weather attributes. One can observe an increase in the intensity of events every seven days for both, i.e. for the police interventions and the communication crimes. In the case of theft, it can be noticed that the events occur mainly at the beginning of the week, and most of them took place between 10 am and 3 pm. Furthermore, the temperature is the basic weather factor associated with the occurrence of violence and crime. The results of the research can be useful for modeling and forecasting the utilization of police forces to prevent and combat crime effectively.

19

Charakterystyka wieloletniej zmienności opadów na obszarach najbardziej narażonych na zjawiska ekstremalne. Część I - Obszar górnej Wisły

Twaróg B.

Gospodarka Wodna

|

2018

|

Nr 4

112--121

PL

Artykuł prezentuje wieloprzekrojową analizę opadów opartą na bazie danych GPCC, średnich miesięcznych na obszarze zlewni górnej Wisły. Analizie poddano dane z okresu 1901 do 2010 r. o rozdzielczości przestrzennej 0,5° x 0,5° długości i szerokości geograficznej. Na wstępie analizy wykonano oceny dokładności danych GPCC w stosunku do danych z okresu 1961-1990 dla obszaru Polski. W kolejnych krokach dane zostały przeanalizowane dla wybranych zlewni górnej Wisły w przekrojach miesięcy oraz okresów hydrologicznych z uwzględnieniem lata i zimy hydrologicznej. Wykonano analizę skupień, wskazując okresy posuszne oraz powodziowe. Dokonano oceny zjawiska okresowości opadów, jak również wykonano obliczenia trendów zmian klimatycznych.

EN

The article presents a multi-sectional analysis of precipitations based on the GPCC database, monthly averages in the area of the upper Vistula catchment area. The analysis covers the data from the period 1901-2010, of the spatial resolution of 0,5° x 0,5° of the geographical longitude and latitude. The analysis starts with an assessment of the GPCC data accuracy with regard to the data for the years 1961-1990 covering the territory of Poland. In the subsequent steps, the data are analysed per selected catchment areas of the upper Vistula River in monthly sections and per hydrological seasons, taking into account the hydrological summer and the hydrological winter. A cluster analysis indicates the drought and flood periods. The author also assesses the precipitations seasonality, as well as makes calculations of the climate change trends.

20

Charakterystyka wieloletniej zmienności opadów na obszarach najbardziej narażonych na zjawiska ekstremalne Część II - Obszar górnej i środkowej Odry

Twaróg B.

Gospodarka Wodna

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2018

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Nr 5

137--145

PL

Artykuł prezentuje wieloprzekrojową analizę opadów opartą na bazie danych GPCC, średnich miesięcznych w zlewni górnej i środkowej Odry. Analizie podda¬no dane z okresu 1901-2010, o rozdzielczości przestrzennej 0,5°x 0,5° długości i szerokości geograficznej. Dane te przeanalizowano w przekrojach miesięcy lat kalendarzowych, jak również lat hydrologicznych, z uwzględnieniem lata i zimy hydrologicznej. Wykonano analizę skupień, wskazując okresy posuszne oraz mokre. Dokonano oceny zjawiska okresowości opadów, jak również obliczono trendy zmian klimatycznych.

EN

The article presents a multi-sectional analysis of precipitations based on the GPCC database, monthly averages in the area of the upper and middle Oder catchment area. The analysis covers the data from the period 1901-2010, of the spatial resolution of 0,5°x 0,5° of the geographical longitude and latitude. The data are analysed in the calendar year monthly cross-sections, as well as hydrological years, taking into account the hydrological summer and the hydrological winter. A duster analysis indicates the drought and wet periods. The author also assesses the precipitations seasonality, as well as makes calculations of the climate change trends.