scholarly journals Effects of Long-Wavelength Track Irregularities Due to Thermal Deformations of Railway Bridge on Dynamic Response of Running Train

2018 ◽  
Vol 8 (12) ◽  
pp. 2549 ◽  
Author(s):  
Sung Ho Hwang ◽  
Sungil Kim ◽  
Kyoung-Chan Lee ◽  
Seung Yup Jang
Keyword(s):  
Temperature Change ◽  
Ride Comfort ◽  
Seasonal Temperature ◽  
Vertical Deformation ◽  
Railway Bridge ◽  
Body Acceleration ◽  
Long Wavelength ◽  
Track Irregularity ◽  
Fixed End ◽  
Track Irregularities

In a fixed-end arch railway bridge restraining the displacement and rotation at the support to constrain the longitudinal deformation of the superstructure, vertical deformation occurs according to temperature change. Due to such deformation, periodic change in long-wavelength track irregularity occurs, which, by increasing the vertical train body acceleration, degrades ride comfort. In the present study, the vertical deformation of a fixed-end arch railway bridge and the accompanying track irregularity changes were measured during the summer and winter, respectively. Based on the measured data, the relationships among the ambient temperature, the temperature of the bridge members, the deformation of the bridge, and the track irregularity were investigated. Additionally, the correlation between the train body acceleration and the long-wavelength track irregularity was examined, and a method of controlling long-wavelength track irregularity considering seasonal temperature change was discussed.

Dynamic Analysis of Linke Hofmann Busch Coach and Determination of its Sensitive Design Parameters Considering Suspended Equipments

2018 ◽  
Vol 10 (4) ◽  
Author(s):  
S.D. Singh ◽  
Rakesh Mathur ◽  
R.K. Srivastava
Keyword(s):  
Ride Comfort ◽  
Low Frequency ◽  
Comfort Level ◽  
Design Parameters ◽  
Bogie Frame ◽  
Long Wavelength ◽  
Stiffness And Damping ◽  
Sensitive Parameters ◽  
Track Irregularities

This study aims at dynamic behaviour of a Linke Hofmann Busch coach and its sensitive parameters against track irregularities considering various suspended equipment. The randomly distributed track irregularities characterized in terms of Indian Rail Road PSD standard are considered main source of excitation that produces undesired vibrations. The coach body and bogie frame subjected to 4 degree of freedom motions (bounce, lateral, roll and pitch) are modelled using finite element methodology where system matrices such as mass, stiffness and damping matrices are obtained for eigenvalue solution. Using modal parameters obtained as above and PSD of track irregularities, both vertical and lateral mean square acceleration responses (MSAR) are determined at various points of concern on coach body. It is observed that the vertical peak responses occur in low frequency range (0-10 Hz) which is caused by long wavelength irregularities of track that causes discomfort. It is also observed that constant peak lateral responses occur at still lower frequency as compared to vertical response which again causes discomfort to vehicle riders. This concludes that there is a further scope of improvement in comfort level with minor adjustments of suspended equipment of a LHB coach. A sensitivity analysis based on the partial derivatives against FRF displacement is conducted and most sensitive design parameters are obtained for optimization to improve ride comfort. It is suggested that if the mass of bio toilet tanks and relative position of battery box + transformer unit i.e. most sensitive parameters of suspended equipment are changed then the ride comfort can be improved

scholarly journals Effect of Long-Wavelength Track Irregularities on Vehicle Dynamic Responses

2019 ◽  
Vol 2019 ◽  
pp. 1-11 ◽  
Author(s):  
Tao Xin ◽  
Pengsong Wang ◽  
Yu Ding
Keyword(s):  
High Speed ◽  
Ride Comfort ◽  
Dynamic Responses ◽  
Vehicle Dynamic ◽  
Long Wavelength ◽  
High Speed Trains ◽  
Train Speed ◽  
Coupling Dynamic ◽  
Track Irregularities

Long-wavelength track irregularities have obvious influence on ride comfort and running stability of high-speed trains. Meanwhile, it brings risk to the inspection of track irregularities since ordinary inspection equipment has difficulties in covering long wavelengths. Previous research on the effect of long-wavelength track irregularities is rare. In order to find the relationship between long-wavelength irregularities and vehicle dynamic responses, a numerical vehicle-track coupling dynamic model based on multibody dynamics and finite element theories is established by using a self-compiling program. One case study is given as an example to show the methodology of determining the sensitive long wavelength and management amplitude of track longitudinal-level irregularities in high-speed railway. The simulation results show that the sensitive long wavelength has a strong correlation with train speed and natural frequency. The simulation and field test results are in good agreement.

Seasonal temperature variations influence tapetum mitosis patterns associated with reproductive fitness

Genome ◽  
2014 ◽  
Vol 57 (9) ◽  
pp. 517-521 ◽  
Author(s):  
Umesh C. Lavania ◽  
Surochita Basu ◽  
Jyotsana Singh Kushwaha ◽  
Seshu Lavania
Keyword(s):  
Climate Change ◽  
Temperature Change ◽  
Reproductive Fitness ◽  
Seasonal Temperature ◽  
Seed Fertility ◽  
Mild Winter ◽  
Differential Behavior ◽  
Sporogenous Tissue ◽  
Differential Behaviour ◽  
Environmentally Sensitive

Environmental stress in plants impacts many biological processes, including male gametogenesis, and affects several cytological mechanisms that are strongly interrelated. To understand the likely impact of rising temperature on reproductive fitness in the climate change regime, a study of tapetal mitosis and its accompanying meiosis over seasons was made to elucidate the influence of temperature change on the cytological events occurring during microsporogenesis. For this we used two species of an environmentally sensitive plant system, i.e., genus Cymbopogon Sprengel (Poaceae), namely Cymbopogon nardus (L.) Rendle var. confertiflorus (Steud.) Bor (2n = 20) and Cymbopogon jwaruncusha (Jones) Schult. (2n = 20). Both species flower profusely during extreme summer (48 °C) and mild winter (15 °C) but support low and high seed fertility, respectively, in the two seasons. We have shown that tapetal mitotic patterns over seasons entail differential behavior for tapetal mitosis. During the process of tapetum development there are episodes of endomitosis that form either (i) an endopolyploid genomically imbalanced uninucleate and multinucleate tapetum, and (or) (ii) an acytokinetic multinucleate genomically balanced tapetum, with the progression of meiosis in the accompanying sporogenous tissue. The relative frequency of occurrence of the two types of tapetum mitosis patterns is significantly different in the two seasons, and it is found to be correlated with the temperature conditions. Whereas, the former (genomically imbalanced tapetum) are prevalent during the hot summer, the latter (genomically balanced tapetum) are frequent under optimal conditions. Such a differential behaviour in tapetal mitosis vis-à-vis temperature change is also correspondingly accompanied by substantial disturbances or regularity in meiotic anaphase disjunction. Both species show similar patterns. The study underpins that tapetal mitotic behaviour per se could be a reasonable indicator to elucidate the effect of climate change on reproductive fitness.

scholarly journals Temperature monitoring of surface layers of the earth in Perm

2019 ◽  
Vol 265 ◽  
pp. 04004
Author(s):  
Andrey Ponomaryov ◽  
Aleksandr Zakharov
Keyword(s):  
Urban Development ◽  
Temperature Change ◽  
Temperature Fluctuations ◽  
Temperature Monitoring ◽  
Clay Soils ◽  
Seasonal Temperature ◽  
Surface Layers ◽  
The Earth ◽  
Geological Conditions ◽  
The City

The article presents the results of monitoring the temperature of the surface layers of the earth. Monitoring was carried out at two sites with engineering-geological conditions typical for Perm. The geological conditions of the first site are clay soils, the second site is sandy. The first site is located in a dense urban development, the second in an unfinished part of the city of Perm. The depth of the soil massif on which the temperature was monitored was: for the first site - 19 m, for the second site - 37 m. Based on monitoring results, a picture of the temperature change in the soil massif in time for both sites was obtained. In the article, the average monthly temperatures of the soil massif are plotted on both sites. The zone of fluctuations in the temperature of the soil massif is revealed depending on the temperature of the outside air. The depth of the zone of seasonal temperature fluctuations was 10m. Monitoring determined that the temperature of the ground mass is below 10m: for the first site + 12 ° C with a decrease in temperature to 10°C to a depth of 19m, for the second site - a constant + 6-7°C to a depth of 37m.

Experimental and numerical investigations of the dynamic responses of an asymmetrical arch railway bridge

2018 ◽  
Vol 232 (9) ◽  
pp. 2309-2323 ◽  
Author(s):  
Hongye Gou ◽  
Yannian He ◽  
Wen Zhou ◽  
Yi Bao ◽  
Genda Chen
Keyword(s):  
Ride Comfort ◽  
Three Dimensional ◽  
Element Model ◽  
Dynamic Responses ◽  
Dynamic Strain ◽  
Railway Bridge ◽  
Coupling System ◽  
Dimensional Finite Element ◽  
Train Speed ◽  
Three Dimensional Finite Element

The dynamic responses of an asymmetrical arch railway bridge subjected to moving trains are experimentally and numerically investigated in this study. The strains, displacements and accelerations at critical sections of the bridge were measured at different speeds of trains. A three-dimensional finite element model of the bridge–vehicle coupling system was established to understand the measured dynamic responses and was validated against the experimental results. The numerical model was used to analyze the influence of asymmetry on the dynamic responses of the bridge and the safety and ride comfort of trains. The results indicate that the dynamic responses of the bridge increase with the train speed. Braking of the train has the largest impact on the vertical dynamic displacement of the bridge. The maximum dynamic strain is in the arch rib. The longer half arch demonstrated much larger counterforce and dynamic responses than those of the shorter half arch, while the symmetrical structures tend to exhibit good symmetry. The asymmetrical arrangement of the bridge reduces the structural stiffness.

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