Effects of Slow-Acting Brakes Application Time Regulated Limits on Freight In-Train Forces

2015 ◽  
Vol 809-810 ◽  
pp. 1133-1138
Author(s):  
Cătălin Cruceanu ◽  
Camil Ion Crăciun
Keyword(s):  
Numerical Simulations ◽  
Air Pressure ◽  
Application Time ◽  
Pressure Data ◽  
Longitudinal Dynamics ◽  
Filling Time ◽  
Tensile Forces ◽  
Filling Characteristics ◽  
Brake Cylinder

The paper originally investigates the influence of the admitted ranges of slow-acting filling time of brake cylinder on longitudinal dynamics of freight trains, using experimental air pressure data obtained in tests on filling characteristics. Mechanical and pneumatic models are summarized and numerical simulations were performed for a train composed of six wagon train, in different filling characteristics configurations. The results reflect significant effects on in-train forces values, while evolution and disposition of compression and tensile forces between neighbored vehicles in the long of the train are also affected.

Effects of Mechanical Wheel Slide Protection Devices Action on Railway Vehicles Braking Process

2015 ◽  
Vol 809-810 ◽  
pp. 1085-1090 ◽  
Author(s):  
Cătălin Cruceanu ◽  
Camil Ion Crăciun ◽  
Ioan Cristian Cruceanu
Keyword(s):  
Cast Iron ◽  
Numerical Simulations ◽  
High Power ◽  
Air Pressure ◽  
Simulation Program ◽  
Disc Brake ◽  
Railway Vehicles ◽  
Protection Devices ◽  
Braking Process ◽  
Brake Cylinder

The paper investigates the effects of mechanical wheel slide protection devices (WSPD) on the braking capacity for coaches equipped with disc or cast iron block brakes. Decelerations and jerks, that affect the passengers comfort, are also analyzed. An original simulation program, based on experimentally determined air pressure evolutions in brake cylinder is used for this purpose. Results of numerical simulations show that in the case of repeated actuations of mechanical WSPDs, disc brake vehicles are more affected in terms of braking capacity. Regarding jerks during braking actions, in both normal and low adhesion conditions, vehicles equipped with high power cast iron block brake with two pressure levels prove to be more affected.

scholarly journals The effects of filling characteristics on the longitudinal forces developed in the braking train

2019 ◽  
Vol 290 ◽  
pp. 08005
Author(s):  
Camil Ion Crăciun ◽  
Cătălin Cruceanu
Keyword(s):  
Compressed Air ◽  
Railway Vehicle ◽  
Inertial Forces ◽  
Longitudinal Dynamic ◽  
Dynamic Forces ◽  
Filling Characteristics ◽  
Brake Cylinder ◽  
Global Research

Determination of longitudinal dynamic forces, size assessment as well as their distribution in the train body is, and will be a subject of global research. As observed from the beginning of the evolution of the railway vehicle and the train itself, the main reason for the occurrence of longitudinal dynamic forces is represented by the differences in inertial forces between the consecutive train vehicles. These inertial forces are influenced by the braking forces developed on each vehicle. The brake with which a railway vehicle is equipped is the pneumatic brake with compressed air. It evacuates the air from the train’s general pipeline, increasing the pressure in the brake cylinders of each vehicle. The brake command and cylinder filling is more delayed on long trains compared to short ones. Thus, the brake can operate in two ways, the fast-action brake and the slow-action brake. In this paper, we aim to highlight the influence of the brake type by the brake cylinder filling characteristic of the dynamic longitudinal reactions. It will be analysed on a simplified train model the magnitude and distribution of longitudinal dynamic forces obtained using both braking systems.

scholarly journals Air pressure propagation through Wind Cave and Jewel Cave: How do pressure waves travel through barometric caves?

2021 ◽  
Vol 50 (3) ◽  
pp. 263-273
Author(s):  
Annika Gomell ◽  
Daniel Austin ◽  
Marc Ohms ◽  
Andreas Pflitsch
Keyword(s):  
Response Times ◽  
External Pressure ◽  
Black Hills ◽  
Air Pressure ◽  
Pressure Waves ◽  
Pressure Gradients ◽  
Pressure Data ◽  
Almost All ◽  
Pressure Changes ◽  
Pressure Propagation

In barometric caves, air pressure gradients between the outside atmosphere and the cave induce strong bidirectional compensating currents, which control almost all elements of speleoclimatology, including air temperature, humidity, and CO2 dynamics. Therefore, this study set out to investigate air pressure propagation through Wind Cave and Jewel Cave – two major barometric cave systems in the Black Hills of South Dakota, USA. Based on high-resolution air pressure data from both the surface and several measurement sites inside the caves, four systematic changes of pressure waves during their journey through the caves and their related speleoclimatological processes were identified and discussed: Compared to the outside atmosphere, the pressure signals within Wind Cave and Jewel Cave showed (1) an absolute displacement due to different altitudes of the measuring sites, (2) a delay related to the travel times of the pressure wave to the measuring sites, (3) a smoothing effect, and (4) a damping effect due to long response times of the caves to external pressure changes. The spatial distribution of the changes observed in this study shows that for Wind Cave, the cave opening and the narrow entrance area represent the main obstacle for pressure propagation, while for Jewel Cave, the deep areas have the greatest influence on the development of air pressure gradients. Our analyses provide completely new insights into the processes and mechanisms inside barometric caves, which will significantly contribute to the understanding of pressure-related airflow dynamics and all related elements of speleoclimatology.

scholarly journals Analysis of Air Pressure Distributions with Wavelets

2016 ◽  
Vol 26 (2) ◽  
Author(s):  
Andreas Baierl
Keyword(s):  
Time Series ◽  
Historical Data ◽  
Air Pressure ◽  
Dependence Structure ◽  
Pressure Data ◽  
Pressure Distributions ◽  
Time Period ◽  
Alternative Approach ◽  
Simulation Purpose ◽  
Parametric Approximation

The article constitutes an alternative approach to transform air pressure distributions for downscaling climate parameters. The objectives include a low-parametric approximation of original pressure surfaces and, in the following, the analysis of the dependence structure of temporal successive distributions for simulation purpose. Wavelets are applied to carry outthe transformation of the distributions. Based on these results, time series analysis is used for the further investigations.The underlying air pressure data covers the relevant region for the central Europeanweather. Daily historical data is available for the time period between 1946 and 1994.

German Bight Storminess over the Last Century

2020 ◽  
Author(s):  
Daniel Krieger ◽  
Oliver Krueger ◽  
Frauke Feser ◽  
Ralf Weisse ◽  
Birger Tinz ◽  
...  
Keyword(s):  
Time Series ◽  
Wind Speed ◽  
German Bight ◽  
Geostrophic Wind ◽  
Air Pressure ◽  
Offshore Wind ◽  
Pressure Data ◽  
Storm Activity ◽  
Wind Speeds ◽  
North East

<p>Assessing past storm activity provides valuable knowledge for economic and ecological sectors, such as the renewable energy sector, insurances, or health and safety. However, long time series of wind speed measurements are often not available as they are usually hampered by inhomogeneities due to changes in the surroundings of a measurement site, station relocations, and changes in the instrumentation. On the contrary, air pressure measurements provide mostly homogeneous time series as the air pressure is usually unaffected by such factors.</p><p>Therefore, we perform statistical analyses on historical pressure data measured at several locations within the German Bight (southeastern North Sea) between 1897 and 2018. We calculate geostrophic wind speeds from triplets of mean sea level pressure observations that form triangles over the German Bight. We then investigate the evolution of German Bight storminess from 1897 to 2018 through analyzing upper quantiles of geostrophic wind speeds, which act as a proxy for past storm activity. The derivation of storm activity is achieved by enhancing the established triangle proxy method via combining and merging storminess time series from numerous partially overlapping triangles in an ensemble-like manner. The utilized approach allows for the construction of robust, long-term and subdaily German Bight storminess time series. Further, the method provides insights into the underlying uncertainty of the time series.</p><p>The results show that storm activity over the German Bight is subject to multidecadal variability. The latest decades are characterized by an increase in activity from the 1960s to the 1990s, followed by a decline lasting into the 2000s and below-average activity up until present. The results are backed through a comparison with reanalysis products from four datasets, which provide high-resolution wind and pressure data starting in 1979 and offshore wind speed measurements taken from the FINO-WIND project. This study also finds that German Bight storminess positively correlates with storminess in the North-East Atlantic in general. In certain years, however, notably different levels of storm activity in the two regions can be found, which likely result from shifted large-scale circulation patterns.</p>

Predicting Shrinkage in Semi-Crystalline Injection Mouldings – The Influence of Pressure

2006 ◽  
Vol 514-516 ◽  
pp. 1501-1505 ◽  
Author(s):  
A.J. Pontes ◽  
António Sergio Pouzada
Keyword(s):  
Experimental Data ◽  
Numerical Simulations ◽  
Pressure Data ◽  
Melt Viscosity ◽  
Effect Of Pressure ◽  
Experimental Pressure ◽  
Pressure Evolution ◽  
Good Agreement

In this study, the as-moulded shrinkage and pressure data are obtained experimentally and compared with numerical simulations. The mouldings were produced in polypropylene (PP). The effect of pressure on viscosity in the predicted pressure evolution was analyzed and also its influence on the shrinkage. The results show that the rise of holding pressure determines the reduction of the shrinkage. Also, it was observed that the pressure predictions are qualitatively in good agreement with the experimental data. However noticeable quantitative discrepancies can be observed when the effect of pressure on viscosity is not considered. If the effect of pressure on the melt viscosity is considered the deviation between predicted and the experimental pressure evolution is substantially reduced.

scholarly journals Implementasi olah data tekanan udara ekstrim dari BMKG untuk meningkatkan hasil belajar siswa pada pokok bahasan tekanan Di SMP Negeri 4 kota Bengkulu

2019 ◽  
Vol 3 (3) ◽  
pp. 160-166
Author(s):  
Ria Agustin ◽  
Muhammad Farid ◽  
Nirwana Nirwana
Keyword(s):  
Learning Outcomes ◽  
Air Pressure ◽  
Instructional Materials ◽  
Control Group ◽  
Pressure Data ◽  
Teaching Materials ◽  
Control Group Design ◽  
Significance Level ◽  
Purposive Sampling ◽  
Group Design

AbstraCT[Implementation of Extreme Air Pressure Data Processing from BMKG to Improve Students Learning Outcomes on the Subject of Pressure in SMPN 4 Bengkulu City]. This Study aims to ;1) produce pressure simulations in the form of images as teaching materials on the concept of air pressure; 2) produce teaching materials in grapichal form so that they. This research is a quasi-experimental research based on purposive sampling technuque  with the   nonequivalent control group design. The sample in this study amounted to two classes, namely VIII.1 as a control class and VIII.2 as an experimental class with a total sample of 30 students in each class. the instrumen in thus study was in the form of objective testa of 10 questions with four answer choices. The results of the study show: 1) air pressure is influenced by temperature, altitude of place and the distribution of oceans and land. Highest air pressure of 1013,8 milibar, lowest air pressure of 1004,0 milibar and the average air pressure of 1008,6 milibar; 2) there are differences in learning outcomes between students taught with instructional materials of extreme air pressure data from BMKG with inquiry models with students taught with a discussion and assignment model shown by  thitung > ttabel ( 7,63 > 2,01) with a significance level 5 %. Keywords: Air pressure; temperature; height; Inquiry. (Received July 27, 2019; Accepted September 18, 2019; Published October 24, 2019) AbstrakPenelitian ini bertujuan untuk:1) mendeskripsikan tekanan udara tertinggi, terendah dan tekanan udara rata-rata, 2) mengetahui perbedaan hasil belajar kognitif siswa antara antara siswa yang diajar menggunakan olah data tekanan udara ekstrim dari BMKG dengan model inkuiri terhadap siswa yang diajarkan menggunakan model diskusi dan penugasan. Penelitian ini adalah penelitian eksperimen semu berdasarkan teknik Purposive Sampling dengan desain nonequivalent control group design. Sampel yang digunakan dalam penelitian ini berjumlah 2 kelas yaitu kelas VIII.1 sebagai kelas Kontrol dan kelas VIII.2 sebagai kelas ekeperimen dengan jumlah sampel dalam tiap kelas sebanyak 30 orang siswa. Instrumen yang digunakan dalam penelitian ini berupa tes objektif  sebanyak 10 soal dengan empat pilihan jawaban.  Hasil penelitian menunjukkan: 1) Tekanan udara dipengaruhi oleh temperature, ketinggian suatu tempat, serta sebaran lautan dan daratan. Tekanan udara tertinggi sebesar 1013,8 milibar, terendah 1004,0 milibar dan rata-rata tekanan udara sebesar 1008,6 milibar; 2) terdapat perbedaan hasil belajar kognitif antara siswa yang diajar menggunakan bahan ajar berupa olah data tekanan udara ekstrim BMKG dengan model inkuiri dengan siswa yang diajar dengan model pembelajaran diskusi dan penugasan yang ditunjukkan dengan thitung > ttabel ( 7,63 > 2,01)dengan taraf signifikasi 5%.Kata kunci: Tekanan udara; temperatur; ketinggian; model Inkuiri.

scholarly journals A Method for Correcting Air-Pressure Data Collected by Mini-AWS

2016 ◽  
Vol 26 (3) ◽  
pp. 182-189 ◽  
Author(s):  
Ji-Hun Ha ◽  
Yong-Hyuk Kim ◽  
Hyo-Hyuc Im ◽  
Deokwhan Choi ◽  
Yong Hee Lee
Keyword(s):  
Air Pressure ◽  
Pressure Data
Sign in / Sign up

Export Citation Format

Share Document