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1

Proactive safety assessment of urban through-roads based on GPS data

Ambros Jiří, Elgner Jan, Valentova Veronika, Bąk Radosław, Kieć Mariusz

Archives of Transport

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2024

|

Vol. 69, iss. 1

113--125

EN

Road safety is a worldwide issue, while urban roads account for a high share of serious road injuries, especially involving vulnerable road users, such as pedestrians or cyclists. Specifically, the safety of major roads through built up areas (through-roads) is insufficient due to mixed traffic conditions including vulnerable road users, varying driving behaviour, and many disruptions, which are combined with excessive speed. In this context, various traffic calming measures have been implemented to improve road safety, such as gateways or pedestrian refuge islands. However, the specific safety impacts of traffic calming combined with specific characteristics of through-roads are often unknown, since most traditional evaluations have been limited by small sample sizes of crash data, as well as wide variations in physical and road characteristics. To overcome the limitations of crash-based evaluations, we used the GPS-based data from a sample of 21 Czech and 12 Polish through-roads to develop the Speed-Safety Index, which combines speed, speed variance, and traffic volume. Our study has three novelty features: (1) To assess safety, we used speed and speed variance simultaneously. (2) To complete the missing link between specific traffic calming measures and safety, we validated the statistical relationship between the developed Speed-Safety Index and crash history. (3) To prove the usefulness of the developed index, we also showed its practical interpretation by proving the effect of spacing between traffic calming measures on safety. The index proved to be well correlated to crash frequency and it also proved the effect of spacing between traffic calming measures: the longer spacing, the smaller speed-reducing effect. The paper concludes with a discussion on the limitations, which we plan to address in further research, by moving from the current macro-perspective (Speed-Safety Index on the level of through-roads) to the micro-perspective (focusing on individual directions, locations, and traffic calming measures). We also plan to investigate the method’s applicability in different contexts. If the approach proves feasible, with reliable and valid results, it may become an alternative for a proactive network-wide road assessment, as called for by the European Road Infrastructure Safety Management Directive.

2

Zderzenie szynobusu z zespołem pojazdów. Zabrakło jednej sekundy…

Młodożeniec Marek

Paragraf na Drodze

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2023

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Nr 2

81--89

PL

W artykule omówiono przypadek zderzenia szynobusu z naczepą. Wskazano przyczynę zderzenia i wpływ przekroczenia dopuszczalnej prędkości przez prowadzącego szynobus na zaistnienie wypadku. Na zakończenie zwrócono uwagę, że do zapobieżenia tego typu zdarzeniom bardzo często wystarczające jest stosowanie się do przepisów art. 25 ust. 2 oraz art. 28 ust. 1 i 2 ustawy Prawo o ruchu drogowym.

EN

A case of railbus – semitrailer collision is discussed. The cause of the collision and the influence of the railbus driver exceeding the permissible speed on the occurrence of the accident are indicated. In conclusion it is emphasized that this type of accidents can very frequently be prevented by conforming to the regulations of art. 25 para. 2 and art. 28 para. 1 and 2 of the Road Traffic Act.

3

Ustalenie rzeczywistej prędkości tramwaju na podstawie wartości zarejestrowanych przez rejestrator ATM

Dąbkowski Paweł Grzegorz, Dylewski Sławomir

Paragraf na Drodze

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2023

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Nr 2

65--79

PL

Celem artykułu jest przedstawienie różnic pomiędzy prędkościami tramwaju zapisanymi w rejestratorze pojazdu a zmierzonymi urządzeniem pomiarowym i wprowadzenia propozycji zastosowania współczynnika korekcyjnego w celu ustalenia rzeczywistej prędkości tramwaju. W czasie eksperymentu realizowanego do jednej z opiniowanych spraw stwierdzono różnice pomiędzy wartościami prędkości zapisanymi w rejestratorze ATM i zmierzonymi urządzeniem VBOX Sport. Zauważono również, że już w rejestratorze zapisane są cztery prędkości, których wartości nie są takie same. W artykule przedstawiono źródła tych prędkości i obliczono współczynnik, który posłużył do odtworzenia rzeczywistych prędkości i przyspieszeń zarejestrowanych w czasie rzeczywistego zdarzenia.

EN

The aim of the article is to present the differences between the tram speeds recorded in the recorder and those measured with a measuring device, and to propose the use of a correlation coefficient to determine the real speed. During the experiment, performed for an expert witness opinion, differences were found between the speed values recorded in the ATM recorder and those measured with the VBOX Sport device. It was also noticed that four speeds of different values had already been recorded in the recorder. The sources of these speeds are presented and the correlation coefficient between the measured and recorded values, which was used to reproduce the actual speeds and accelerations recorded during the real event, is calculated.

4

Frictional Aspects of Operation for Centrifugal Accelerators with Radial Blades

Krupicz Bazyli, Barsukov Vladimir G., Ilkevich Maria A.

Tribologia

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2022

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nr 3

39--48

EN

The work aims to determine the friction effect and change the velocity and kinetic energy during the movement of solid particles along the rotating machine's radial blade surface. It has been previously shown that the influence of the frictional forces of the particle against the rotor disc is negligible compared to the influence of the centrifugal force and the friction force of the particle against the rotor blade. Based on the analysis of the differential equation solution for particle motion along the surface of the blades, it was established that the total sliding velocity of a particle increase intensively in the initial period of motion and approaches asymptotically to the values described by a linear function, practically independent of the initial position of the particle. The obtained analytical expressions enable the determination of change in the relative and total velocity of the particle, the angle between the respective velocity vectors and its kinetic energy. Changes in the values of these parameters were also estimated for a wide range of variability of the friction coefficient.

PL

Celem pracy jest określenie wpływu tarcia cząstek stałych na ich prędkość i straty energii kinetycznej podczas ruchu po powierzchni łopatek promieniowych maszyn wirnikowych. Wykazano, że wpływ sił tarcia cząstki o tarczę wirnika jest pomijalnie mały w porównaniu z wpływem siły odśrodkowej i siły tarcia cząstki o łopatkę wirnika. Na podstawie analizy rozwiązania równania różniczkowego ruchu cząstek po powierzchni łopatek ustalono, że całkowita prędkość poślizgu cząstki intensywnie wzrasta w początkowym okresie ruchu i zbliża się asymptotycznie do wartości opisanych funkcją liniową, praktycznie niezależną od położenia początkowego cząstki. Uzyskane wyrażenia analityczne umożliwiają określenie: zmiany prędkości względnej i całkowitej cząstki, kąta pomiędzy odpowiednimi wektorami prędkości oraz jej energii kinetycznej. Dokonano również oszacowania zmiany wartości tych parametrów dla szerokiego zakresu zmienności współczynnika tarcia.

5

Obowiązki kierujących pojazdami i pieszych przechodzących przez przejście dla pieszych po nowelizacji ustawy Prawo o ruchu drogowym

Stefański Ryszard A.

Paragraf na Drodze

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2022

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Nr 1

7--19

PL

Przedmiotem artykułu jest analiza zmian dotyczących przechodzenia pieszego po przejściu dla pieszych, wprowadzonych ustawą z dnia z dnia 25 lutego 2021 r. o zmianie ustawy Prawo o ruchu drogowym. Jego celem jest wykładnia użytego w art. 13 ust. 1a ustawy Prawo o ruchu drogowym (dalej p.r.d.) pojęcia pieszy wchodzący na przejście dla pieszych, a także jego obowiązków w postaci zachowania szczególnej ostrożności, niewchodzenia na jezdnię bezpośrednio przed jadący pojazd oraz niekorzystania z telefonu lub innego urządzenia elektronicznego. Rozważania zmierzały także do wyjaśnienia pozostających w związku z uprawnieniem pieszego obowiązków kierującego pojazdem zbliżającego się do przejścia dla pieszych polegających na zmniejszeniu prędkości tak, aby nie narazić na niebezpieczeństwo pieszego znajdującego się na tym przejściu albo na nie wchodzącego oraz ustąpieniu pierwszeństwa pieszemu wchodzącemu na to przejście. Dla osiągnięcia tych celów zostały wykorzystane takie metody badawcze jak analiza tekstu normatywnego, metoda językowa i logiczna. Artykuł ma znaczenie - ze względu na wyjaśnienie kontrowersji jakie rodzi art. 13 ust. 1a p.r.d. - przede wszystkim dla biegłych z zakresu ruchu drogowego oraz kierowców i pieszych.

EN

The subject of the article is an analysis of the amendments regarding a pedestrian walking across pedestrian crossing, introduced by the Act of February 25, 2021 amending the Act on Road Traffic. Its aim is to interpret the concept, provided in Article 13 (1a) of the Act on Road Traffic, of a pedestrian entering a pedestrian crossing as well as his/her duty to exercise special care, not to enter the road directly in front of a moving vehicle and not to use a telephone or other electric devices. The considerations were also aimed at clarifying the obligations, related to pedestrians rights, of the driver of the vehicle approaching the pedestrian crossing, consisting in reducing the speed so as not to endanger the pedestrian on this crossing or entering it, and giving way to a pedestrian entering the zebra crossing. To achieve these goals, research methods such as the analysis of the normative text together with linguistic and logical methods were used. The article is important as it clarifies the controversy arising from Art. 13 (1a) of the Act on Road Traffic primarily to road traffic experts, drivers and pedestrians.

6

Możliwości odtworzenia prędkości pojazdu na podstawie nagrania z kamery pokładowej

Tokař Stanislav

Paragraf na Drodze

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2022

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Nr 1

43--54

PL

Na podstawie dwóch zdarzeń drogowych pokazano, jakie są możliwości ustalania prędkości pojazdów przed kolizją z wykorzystaniem analizy nagrań wideo pochodzących z kamer pokładowych i geodezyjnego pomiaru miejsca zdarzenia. Pozyskane informacje pozwoliły na odtworzenie ruchu uczestników kolizji przy wykorzystaniu metody modelowania symulacyjnego, co dało możliwość wskazania na przyczyny kolizji.

EN

On the basis of two road traffic incidents the possibilities of specifying vehicles speeds prior to collision by analysing the video recordings from on-board cameras and geodetic measurements are shown. Owing to the thus obtained data it was possible to reconstruct the movements of the participants of the collisions, using the simulation modelling method, which enabled the identification of the causes of the collisions.

7

Simulation features of the impeller in a centrifugal pump

Mykhailiuk Vasyl, Fafaley Oleh, Deynega Ruslan, Mosora Yurii

Mining Machines

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2022

|

vol. 40, iss. 1

1--7

EN

To ensure the operability of machinery and equipment for the oil and gas industry, it is important to study their operation with subsequent improvement. This scientific work is devoted to highlighting the operation simulation of the impeller in a submersible centrifugal pump, because the pump itself is the main equipment in oil production. The main parts of a submersible centrifugal pump are its stages, consisting of an impeller and a guide vane. When the impeller rotates, a force interaction of the flow with the impeller blades occurs, while a pressure difference in the fluid flow on both sides of each blade arises. The pressure forces of the blades on the flow create a forced rotational and translational motion of the fluid, increasing its mechanical energy. It should be noted that the movement of fluid in pump sections is a rather complex process that is difficult to accurately describe analytically. However, today there are various computer programs (SOLIDWORKS FlowSimulation, ANSYS CFD, etc.) based on the finite volume method (FVM). To study the operation of a submersible centrifugal pump impeller, there has been built its threedimensional model. As a result of calculations, the distribution of pressure and velocity in the cross section of the impeller was obtained.

8

The influence of the police on vehicle speed in built-up areas

Dębiński Marcin, Bohatkiewicz Janusz

Budownictwo i Architektura

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2022

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Vol. 21, no 2

17--30

EN

In many cases, the effects of road accidents have significant impact on human health. This translates directly into society, in both material and emotional terms. The severity of the injury in a road event depends largely on the speed of the vehicles. Excessive vehicle speed is of particular concern in incidents involving vulnerable road users. As confirmed by literature analysis and research, in most cases drivers do not respect the speed limits introduced by the road signs. Existing solutions allow to introduce permanent or temporary speed control. This paper investigates speeding and driver behaviour in built-up areas near schools and pedestrian crossings. The aim of the research described in the paper is to determine the influence of the effectiveness of police actions on speed reduction and improvement of road safety.

9

Effect of the wind speed and direction on energy balance in building

Pilarska Malwina

Polish Technical Review

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2021

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No. 2

35--40

EN

In the present paper, the problems connected with the direction and velocities of the wind, having a significant effect on energy balance in a building, have been discussed. The discussed issue concerns the construction object (10-floor skyscraper) being shielded with many obstructions, which is affected by wind activity. The analysis concerns also the balance of heat energy of the discussed building which serves keeping of thermal comfort and by this, it is a summarization of heat profits in the building, obtained from internal heat sources and solar profits, connected with the losses, caused by heat transfer via external construction baffles and ventilation system. The problem connected with the wind and its role in the energy balance has been also presented. Apart from a good thermal insulation of external baffles, the coefficient of heat loss caused by heat transfer plays also a meaningful role. The mentioned building has been subjected to analysis which concerns the impact of the direction and speed of the wind on the heat transfer coefficient. The aim of the study was to determine the influence of the direction and speed of the wind on the value of heat transfer coefficient. As far as the dynamic values of surface heat coefficient are concerned, they have been presented in the table.

PL

W artykule zostały poruszone zagadnienia związane z kierunkiem oraz prędkością wiatru, który ma istotny wpływ na bilans energii w budynku. Została poruszona tutaj kwestia, która dotyczy obiektu budowlanego (10 piętrowego wieżowca) osłoniętego wieloma przeszkodami, na który ma wpływ działanie wiatru. Analiza dotyczy również bilansu energii cieplnej budynku , która służy do utrzymania komfortu cieplnego, a tym samym stanowi sumaryczne zestawienie zysków ciepła w budynku otrzymanego z wewnętrznych źródeł ciepła oraz zysków solarnych związanych ze stratami spowodowanymi przenikaniem przez zewnętrzne przegrody budowlane oraz wentylację. Została również przedstawiona kwestia związana z wiatrem oraz jego rolą w bilansie energii. Oprócz dobrej izolacji termicznej przegród zewnętrznych duże znaczenie ma tutaj współczynnik strat ciepła przez przenikanie. Budynek został poddany analizie, która dotyczy kierunku i prędkości wiatru na współczynnik przenikania ciepła, badanie miało na celu ustalenie jaki wpływ na wartość współczynnika przenikania ciepła ma kierunek i prędkość wiatru. Jeżeli chodzi o wartości dynamiczne przejmowania ciepła na zewnętrznej powierzchni zostały przedstawione w pracy w tabeli.

10

Prędkość ruchu dziecka na hulajnodze. Wyniki badań pilotażowych

Wyznakiewicz Paweł

Paragraf na Drodze

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2021

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Nr 2

67--73

PL

W artykule przedstawiono wyniki badań pilotażowych czasu przemieszczania się na zadanym odcinku drogi chłopca w wieku 11 lat na hulajnodze napędzanej siłą mięśni. Wykonując badania drogowe określano czas przejazdu hulajnogą odcinka pomiarowego długości 10 m ze stałą prędkością, a także czas przejazdu tego samego odcinka pomiarowego ze startu zatrzymanego. Próby wykonano dla jazdy wolnej, normalnej szybkiej. Podano wartości minimalne, maksymalne oraz wyznaczono średnie wartości czasów w zależności od tempa poruszania się. Na podstawie uzyskanych wyników obliczono średnie wartości prędkości hulajnogi, które wynoszą 2,6 m/s dla jazdy wolnej, 3,2 m/s dla jazdy normalnej i 4,5 m/s dla jazdy szybkiej.

EN

The aim of the article is to present the results of pilot studies on the time of covering a given distance by an 11-year-old boy on a human powered scooter. In the road tests the time of covering the distance of 10 m on a scooter at a constant speed and the time of covering this distance from a standing start were established. The tests were performed for a slow, normal and fast runs. The minimal and maximal values were given, and mean times vs. movement speed identified. Based on the results the mean values of the scooter movement were calculated: 2.6 m/s for slow run, 3.2 m/s for normal run and 4.5 m/s for fast run.

11

Jak biegły do spraw wypadków drogowych „może” wypowiadać się o intencjach obwinionego?

Księżopolski Jacek

Paragraf na Drodze

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2021

|

Nr 3

55--66

PL

Artykuł przedstawia metodę opiniowania zdarzeń drogowych, udokumentowanych zapisem monitoringu, w których istnieje podejrzenie świadomego sprowokowania kolizji przez jednego z uczestników. Rozważania oparto na konkretnym zdarzeniu, w którym taką możliwość sugerowały zarówno dowody osobowe, jak i informacje o uczestniczeniu jednego z kierujących w dużej ilości podobnych zdarzeń drogowych. Pomimo że w przedmiotowej sprawie pytania skierowane do biegłego były sformułowane wyjątkowo ogólnikowo, to w istocie sprowadzały się do ustalenia, czy intencją obwinionego - kierującego, posiadającego pierwszeństwo przejazdu, było sprowokowanie zderzenia w okolicznościach wskazujących na odpowiedzialność drugiego uczestnika zdarzenia za jego wystąpienie. Oczywistym jest, że bezpośrednia odpowiedź na tego typu pytania byłaby skazana na zarzut przekroczenia kompetencji, ale odpowiednio przygotowana analiza może dać organowi procesowemu podstawę do samodzielnego ustalenia, jakie były intencje obwinionego.

EN

A method of producing expert opinions on road traffic accidents evidenced by monitoring system recording, in which one of the participants is suspected of having deliberately orchestrated the collision is presented. The discussion was based on an actual event in which such a possibility was suggested by both the witnesses’ testimony as well as information on the participation of one of the drivers in a large number of similar events. Despite the fact that the questions the court expert was asked were formulated in an extremely general way, they were essentially aimed at establishing whether it was the intention of the defendant - the driver who had the right of way to provoke the collision in circumstances indicating the responsibility of the other participant. Obviously, a direct answer to this type of question was doomed to the complaint of exceeding the competences. However, an adequately formulated analysis may provide the judicial authority with a basis for an independent decision as to what the defendant’s intentions were.

12

Modelling of work of the rotor-type blade pump with revolving stator

Dmytriv V. T., Lanets O. S., Dmytriv I. V., Horodetskyy I. M.

International Journal of Applied Mechanics and Engineering

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2021

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Vol. 26, no. 4

17--28

EN

In the article, the analytical dependences of modelling the cell cross-sectional area between two adjacent blades of a rotary blade pump and capacity for a pump with fixed and rotating stators are given, and analytical dependences are derived to model the power necessary to overcome the friction forces of the blades. The forces acting on the radially placed blade of a rotary pump with a fixed stator (non-rotating or stationary) and a rotating stator are analyzed. Design and technological parameters that influence the pump capacity and power are taken into account. The power required for the movement of the pump blade without taking into account the compression of the air has the opposite character of the change as to the pump capacity The capacity of a rotary pump with a rotating stator is three times higher than that of a stationary stator. The rotary pump with a rotating stator, with six radially spaced blades, consumes 0.854 [kW] less power to overcome the blade friction of 1313 kW The results of modelling of the pump work are given.

13

Sight distances at unsignalized intersections: a comparison of guidelines and requirements for human drivers and autonomous vehicles

Magyari Zsofia, Koren Csaba, Kieć Mariusz, Borsos Attila

Archives of Transport

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2021

|

Vol. 59, iss. 3

7--19

EN

Many traffic accidents are caused by unforeseen and unexpected events in a site that was hidden from the driver's eyes. Road design parameters determining required visibility are based on relationships formulated decades ago. It is worth reviewing them from time to time in the light of technological developments. In this paper, sight distances for stopping and crossing situations are studied in relation to the assumed visual abilities of autonomous vehicles. Current sight distance requirements at unsignalized intersections are based among others on speeds on the major road and on accepted gaps by human drivers entering or crossing from the minor road. Since these requirements vary from country to country, regulations and sight terms of a few selected countries are compared in this study. From the comparison it is remarkable that although the two concepts, i.e. gap acceptance on the minor road and stopping on the major road have different back-grounds, but their outcome in terms of required sight distances are similar. Both distances are depending on speed on the major road: gap sight distances show a linear, while stopping sight distances a parabolic function. In general, European SSD values are quite similar to each other. However, the US and Australian guidelines based on gap acceptance criteria recommend higher sight distances. Human capabilities and limitations are considered in sight field requirements. Autonomous vehicles survey their environment with sensors which are different from the human vision in terms of identifying objects, estimating distances or speeds of other vehicles. This paper compares current sight field requirements based on conventional vehicles and those required for autonomous vehicles. Visibility requirements were defined by three vision indicators: distance, angle of view and resolution abilities of autonomous cars and human drivers. These indicators were calculated separately for autonomous vehicles and human drivers for various speeds on the main road and for intersections with 90° and 60° angles. It was shown that the required sight distances are 10 to 40 meters shorter for autonomous vehicles than for conventional ones.

14

Analysis of safety impact of paved shoulder width on Czech secondary roads

Ambros Jiří, Křivánková Zuzana, Zůvala Robert, Bucsuházy Kateřina, Frič Jindřich

Archives of Transport

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2021

|

Vol. 60, iss. 4

125--136

EN

Traffic safety is influenced, among other factors, by characteristics of the roads, which include the width of the shoulder. Shoulder width was noted to have a large effect on crash frequency, as well as on traffic speed. In this paper, we focused on paved shoulders. Previous studies confirmed that increasing the width of the paved shoulder is associated with a decrease in crash frequency. However, wider shoulders may encourage higher driving speed, which is related to an increase of impact speed and crash severity – this issue was hypothesized, but not statistically investigated. Thus, conclusions based on crashes and speeds contradict each other, and there is no simple answer to the question of the safety impact of wide shoulders. To address this gap, we analyzed a sample of two most typical categories of Czech secondary roads, which differ only in the paved shoulder width (S9.5 roads with 0.75m-wide shoulder, and S11.5 roads with 1.75m-wide shoulder) and thus present a suitable example for studying the safety impact of paved shoulder width. We used generalized linear models of crash frequency, and multinomial logistic models of crash severity (separately for single-vehicle and multi-vehicle crashes), as well as a statistical test of differences in speed for the two road categories. The results showed that: Firstly, there were fewer crashes on S11.5 roads compared to S9.5 roads; this was true for both single-vehicle and multi-vehicle crashes. Secondly, single-vehicle crashes on S11.5 roads were more severe compared to S9.5 roads; the change of severity in multi-vehicle crashes was not statistically significant. Thirdly, driving speeds on S11.5 roads were approx. by 7 km/h higher compared to S9.5 roads. These findings support the hypothesis of an association between wider shoulders, higher speeds, and increased crash severity, especially in the case of single-vehicle crashes. As a practical solution, various speed management measures, including widening to a 2+1 road, may be recommended.

15

Optymalizacja parametrów cięcia laserowego materiałów obuwniczych

Alvarez Joanna, Pieknik Marcin

Technologia i Jakość Wyrobów

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2020

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R. 65

79--91

PL

Przedstawiono wyniki optymalizacji parametrów laserowego cięcia materiałów obuwniczych, tj. prędkości oraz mocy. Testom poddano wybrane materiały zróżnicowane surowcem i/lub sposobem wytwarzania, grubością, a także docelowym przeznaczeniem. Na podstawie przeprowadzonych testów stwierdzono, że właściwości fizyczne promieniowania lasera CO2 – Maximus PRO (model: JSM 90 x 60), pozwalają zapewnić wysoką jakość obróbki dowolnych materiałów obuwniczych. Efekty wizualne cięcia zależą od precyzji ustawień ogniskowej pomiędzy płaską powierzchnią cięcia i głowicą lasera oraz parametrów prędkości i mocy lasera. Konieczny jest więc ich każdorazowy dobór na podstawie przeprowadzonych testów kontrolnych.

EN

The results of optimizing laser cutting parameters of footwear materials, i.e. speed and power, are presented. Selected materials were tested, differing in terms of raw material and/or manufacturing method, thickness and intended use. On the basis of the tests, it was found that the physical properties of CO2 laser radiation – Maximus PRO (model: JSM 90 x 60), ensure high quality processing of any footwear materials. The visual effects of the cut depend on the precision of the focal length settings between the flat cutting surface and the laser head, as well as the speed and laser power parameters. Therefore, it is necessary to always select them on the basis of the control tests.

16

Destruction of the Structure of Boiling Emulsions

Pavlenko Anatoliy, Melnyk Viktor

Rocznik Ochrona Środowiska

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2020

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Tom 22, cz. 1

70--81

EN

In this paper we consider the processes of dynamic interaction between the boiling particles of the dispersed phase of the emulsion leading to the large droplet breakup. It is indicated the differences in the consideration of forces that determine the crushing of non-boiling and boiling drops. It is determined the possibility of using the model to define the processes of displacement, deformation or fragmentation of the inclusion of the dispersed phase under the influence of a set of neighboring particles. The proposed method allows us to determine the main energy parameters of the homogenization process by boiling the emulsion.

PL

W tym artykule rozważamy procesy dynamicznej interakcji między wrzącymi cząsteczkami zdyspergowanej fazy emulsji, prowadzące do rozpadu dużych kropel. Wskazano na różnice w uwzględnianiu sił, które determinują kruszenie kropli niewrzących i wrzących. Określono możliwość wykorzystania modelu do zdefiniowania procesów przemieszczenia, deformacji lub fragmentacji włączenia fazy rozproszonej pod wpływem zestawu sąsiednich cząstek. Proponowana metoda pozwala określić główne parametry energetyczne procesu homogenizacji podczas ogrzewania i wrzenia emulsji.

17

Effect of engine speeds and dimethyl ether on methyl decanoate HCCI combustion and emission characteristics based on low-speed two-stroke diesel engine

Wang Shiye, Yao Li

Polish Maritime Research

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2020

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nr 2

85--95

EN

The combustion and emission characteristics of homogeneous charge compression ignition (HCCI) fuelled by methyl decanoate (MD) with different engine speeds and dimethyl ether (DME) mixing ratios are investigated in this work. Engine data of a MAN B&W 6S70MC low-speed two-stroke marine diesel engine were used for the reactor. The results show that a decrease of engine speed has little effect on the in-cylinder temperature and pressure of the engine at constant excess air coefficient of 1.5. Meanwhile, NOx emissions decrease with a decrease of engine speed in pure MD HCCI combustion. The results also indicate that NOx and CO2 emissions decrease significantly with an increase in the percentage of DME in MD and DME mixing combustion at a constant total mole fraction and engine speed of 85 revolutions per minute (r/min).

18

Obliczanie prędkości motocykla na podstawie długości śladów jego sunięcia pozostawionych na podłożu. Korekta wzoru podanego w publikacji C. Glynna i D. P. Wooda, opublikowanego w numerze 4/2016 czasopisma Paragraf na Drodze

Ciępka Piotr

Paragraf na Drodze

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2020

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Nr 4

71--77

PL

W artykule przedstawiono weryfikację zależności, podanej w publikacji Colyna Glynna i Denisa P. Wooda pt. Metody rekonstrukcji wypadków z udziałem motocykli. Szacowanie powypadkowej prędkości przewróconego motocykla na podstawie śladów jego sunięcia po podłożu. Artykuł ten został opublikowany w numerze 4/2016 czasopisma Paragraf na Drodze. Weryfikacja ta oparta została na rzeczywistym przypadku zdarzenia, które opiniował autor niniejszego artykułu. Przedstawiona sytuacja stanowi ilustrację zasady mówiącej, że nie można bezkrytycznie podchodzić do wyników obliczeń i każdy wynik należy kontrolować, pod kątem możliwości popełnienia błędu grubego. Autor, po powzięciu wątpliwości, dotarł do pierwotnego tekstu, w którym wykorzystywany w obliczeniach wzór miał nieco inną postać niż podana w przywołanym artykule, a jego zastosowanie dawało już wyniki zbieżne z oczekiwanymi. Na zakończenie autor zwrócił uwagę na błąd w taktyce awaryjnego zatrzymywania hamowania motocykla, jaki niejednokrotnie popełniają motocykliści, doprowadzając do położenia motocykla.

EN

Correction of the formula given in the paper by Colyn Glynn and Denis P. Wood Motorcycle reconstruction methods. Motorcycle speed evaluation from its post-crash slide distance is presented. The paper was published in the 4/2016 issue of Paragraph on the Road journal. The formula has been verified on a real-life road event the expert evidence of which was reported by the author of the present article. This case illustrates a principle which says that no calculation results should be approached uncritically and each result should be checked for the possibility of making a grave error. To dispel his doubts, the author reached for the source manuscript in which the formula employed in the calculations was slightly different than the one given in the paper referred to, and its use yielded results convergent with the expected ones. Finally, the author points out the unsuitable tactic of motorcycle emergency braking, frequently adopted by motorcycle riders, which ends in laying the motorcycle on its side.

19

Anemometric conditions in the area of Bydgoszcz in the years 1971–2010 using the example of the Bydgoszcz-Airport weather station

Łaszyca Edward Zbigniew

Geography and Tourism

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2020

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Vol. 8, No. 2

107--119

EN

This paper refers to the characteristics of anemometric conditions in the area of Bydgoszcz based on data sourced from the Bydgoszcz-Airport weather station in 1971–2010. Annual mean wind speed measured in a multi-annual period was higher in the winter half-year and lower in the summer half-year, which is typical of the climate of central Poland. In the analysed multi-annual period, the annual mean wind speed was 3.3 m·s-1. The annual curve of average wind directions in the multi-annual period was characterised by a prevailing share of west wind, followed by that of south, east and north winds. The prevailing average wind direction in the analysed multi-annual period was west wind (W), followed by southwest (SW), northwest (NW), southeast (SE), east (E), south (S), north (N) and northeast (NE) wind.

20

Where and when do drivers speed? A feasibility study of using probe vehicle data for speeding analysis

Ambros Jiří, Elgner Jan, Turek Richard, Valentova Veronika

Archives of Transport

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2020

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Vol. 53, iss. 1

103--113

EN

Speed is a critical transportation concept – it is one of the most important factors that road users consider in relation to route convenience and efficiency; at the same time speed has been recognized as the most influential risk factor. To improve speeding analyses, an emerging data source – probe vehicle data (also known as floating car data), may be used. This data enables obtaining information on vehicle speeds, without being limited in time and space. To prove the feasibility of using this data, a study was conducted on a sample of Prague expressway and collector roads. Firstly, probe data sample validity was checked through comparison to a traditional speed measurement technique – average speed control. Secondly, descriptive analysis of speeding was performed, focusing on speeding differences across homogeneous road segments in individual hour intervals. Thirdly, statistical models were also developed to explain which road parameters contribute to speeding. Analysis utilized cross-section and geometry parameters, which may potentially be related to speed choice and driving speed and speeding. In general, the applied concept proved as feasible: particularly night time was found more prone to speeding, and the rates were significantly different between segments. Statistical models indicated the statistically significant influence on speeding: lower speed limit, lower number of lanes, absence of roadside activities, or presence of horizontal curves. Information on these factors may be generalized and used for planning adequate speeding countermeasures. Final discussion also identified and described several challenges for future research, including free-flow speed estimation uncertainty, quality of speed-safety models, and potential multicollinearity of explanatory variables.