Numerical and experimental investigations of the effect of temperature and moisture on the repose angle of railway ballast

2021 ◽  
pp. 095440972110393
Author(s):  
Jianxing Liu ◽  
Ping Wang ◽  
Ganzhong Liu ◽  
Shuai Du ◽  
Rong Chen ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Low Temperature ◽  
Angle Of Repose ◽  
Effect Of Temperature ◽  
Experimental Investigations ◽  
Railway Ballast ◽  
Influence Of Temperature ◽  
Surface Method ◽  
The Difference ◽  
Validity Tests

The angle of repose (AOR) is one of the key parameters used to comprehensively characterize the basic mechanical properties and stacking properties of granular materials. In this research, the influence of temperature and moisture on the stacking performance of railway ballast was studied through tests of the AOR. Additionally, the parameters of the discrete element method (DEM) for ballast beds with various temperatures and moisture levels were calibrated and combined with the response surface method. Then, the AORs of the ballast in different environments were simulated with the DEM, and the micromechanical properties of the ballast in dry, wet, low-temperature, and frozen environments were compared. The results showed that the AOR of the ballast in a frozen environment was smaller than that in a dry environment at the same low temperature (the difference could reach 8.48° at −30°C). The AOR of the ballast increased with the decrease of the temperature in a dry environment (18.44% increase between 20°C and −30°C). The AOR of the ballast decreased with the decrease of the temperature in a wet (frozen) environment (22.86% decrease between 20°C and −30°C). In addition, the validity tests of the AOR simulations of ballast proved that the obtained parameters could be used in the DEM models of ballast for the corresponding temperature and moisture. At the same time, it was found that with the change of temperature and moisture, the force chain network of the ballast would also change.

Low Temperature Densification of ZnO-Based Ceramic Using Phenolic Resin as Binder

2014 ◽  
Vol 668-669 ◽  
pp. 35-38
Author(s):  
Hui Zeng ◽  
Jing Jing Xie ◽  
Hai Tao Liu ◽  
Zheng Yi Fu
Keyword(s):  
Mechanical Properties ◽  
Boundary Layer ◽  
Low Temperature ◽  
Grain Boundary ◽  
Phenolic Resin ◽  
Bending Strength ◽  
Effect Of Temperature ◽  
Microstructure And Mechanical Properties

ZnO-based ceramic was densified at low temperature by using PSP as binder. The results showed that phenolic resin filled in the ZnO grain boundary layer. The sample has a well hardness of 0.8 GPa and bending strength of 78 MPa. The effect of temperature on the microstructure and mechanical properties was also investigated. It was found that the samples sintered at 300 °C showed higher density and better mechanical properties.

Effect of Temperature on Crater Formation and Ejecta Composition in Aluminum Alloy Targets

2012 ◽  
Vol 706-709 ◽  
pp. 768-773
Author(s):  
Masahiro Nishida ◽  
Koichi Hayashi ◽  
Junichi Nakagawa ◽  
Yoshitaka Ito
Keyword(s):  
Aluminum Alloy ◽  
High Temperature ◽  
Low Temperature ◽  
Room Temperature ◽  
Effect Of Temperature ◽  
Crater Formation ◽  
Influence Of Temperature ◽  
Gas Gun ◽  
Influence Of Temperature On ◽  
Increasing Temperature

The influence of temperature on crater formation and ejecta composition in thick aluminum alloy targets were investigated for impact velocities ranging from approximately 1.5 to 3.5 km/s using a two-stage light-gas gun. The diameter and depth of the crater increased with increasing temperature. The ejecta size at low temperature was slightly smaller than that at high temperature and room temperature. Temperature did not affect the size ratio of ejecta. The scatter diameter of the ejecta at high temperature was slightly smaller than those at low and room temperatures.

scholarly journals EFFECT OF TEMPERATURE AND pH OF MODIFICATION PROCESS ON THE PHYSICAL-MECHANICAL PROPERTIES OF MODIFIED CASSAVA STARCH

Molekul ◽  
2016 ◽  
Vol 11 (2) ◽  
pp. 248 ◽  
Author(s):  
Yudi Wicaksono ◽  
Nuri Nuri ◽  
Budipratiwi Wisudyaningsih
Keyword(s):  
Mechanical Properties ◽  
Cassava Starch ◽  
Effect Of Temperature ◽  
Swelling Power ◽  
Starch Modification ◽  
Compression Properties ◽  
Modification Process ◽  
The Difference ◽  
Starch Modifications ◽  
Pvp K30

The use of cassava starch for excipient in the manufacturing of the tablet has some problems, especially on physical-mechanical properties. The purpose of this study was to determine the effect of the differentness of temperature and pH in the process of modification on the physical-mechanical properties of modified cassava starch. Modifications were performed by suspending cassava starch into a solution of 3 % (w/v) PVP K30. The effect of the difference of temperature was observed at temperatures of 25; 45 and 65 0C, while the effect of the difference of pH was observed at pH of 4.0; 7.0 and 12.0. The results showed that the temperature and pH did not affect the physical-mechanical properties of the modified cassava starch. Modification of cassava starch at pH and temperature of 7.0 and 45 0C was produced modified cassava starch with the most excellent solubility, while the best swelling power were formed by the modification process at pH and temperature of 7.0 and 25 0C. Overall, the most excellent compression properties of modified cassava starch resulted from the modification process at pH 12.

The Effect of Mineral Admixtures on Mechanical Properties of High Performance Concrete at very Low Temperature

2014 ◽  
Vol 584-586 ◽  
pp. 1509-1513
Author(s):  
Nan Zhang ◽  
Juan Liao ◽  
Tao Zhang ◽  
Wen Zhan Ji ◽  
Bao Hua Wang ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Compressive Strength ◽  
Low Temperature ◽  
High Performance ◽  
High Performance Concrete ◽  
Splitting Tensile Strength ◽  
Mineral Admixtures ◽  
The Difference ◽  
Very Low Temperature

The effect of very low temperature on high performance concrete (HPC) mechanical properties is studied by using a reasonable testing method. The results show that the compressive strengths of concrete are increasing with lower temperatures. Fly ash (FA), compared to ground granulated blast-furnace slag (GGBFS), is positive to the compressive strength increasing at low temperature. The splitting tensile strengths of concrete appear a maximum at-40°C~-80°C. The compound replacement by GGBFS and FA makes the splitting tensile strength present the extreme value at higher temperature. At very low temperature, the single or compound replacement by mineral admixtures can result in the difference of the relationship between compressive strength and splitting tensile strength, and the degradation of concrete subjected to cold-thermal shocks.

The influence of physical factors on the survival and infectivity of miracidia ofSchistosoma mansoniandS. haematobiumI. Effect of temperature and ultra-violet light

1977 ◽  
Vol 51 (1) ◽  
pp. 73-85 ◽  
Author(s):  
S. K. Prah ◽  
C. James
Keyword(s):  
Low Temperature ◽  
Old Age ◽  
Ultra Violet ◽  
Effect Of Temperature ◽  
Physical Factors ◽  
Influence Of Temperature ◽  
Violet Light ◽  
Ultra Violet Radiation ◽  
Turbid Waters ◽  
Violet Radiation

ABSTRACTThe influence of temperature and ultra-violet radiation on the degree of activity, survival and infectivity of schistosome miracidia is profound. Miracidia ofSchistosoma mansoniandS. haematobiumwere affected equally. Only miracidia classified as “active” or “slow” were capable of penetration, a capacity they retained for about 17 hours at 19°C. Miracidia that were “lethargic” as a result of low temperature, old age or ultra-violet radiation lost their infective capacity. The conclusion, however, is that neither the temperatures encountered in the field nor the solar ultra-violet radiation penetrating turbid waters are likely to be harmful to miracidia and thus have no effect on the level of transmission.

Stress Field Simulation of Concrete Structure Considering Influence of Temperature on Autogenous Volume Deformation

2012 ◽  
Vol 482-484 ◽  
pp. 1321-1324
Author(s):  
Xiao Yue Zhang ◽  
Shao Ping Liu
Keyword(s):  
Stress Field ◽  
Concrete Structure ◽  
Influence Factors ◽  
Effect Of Temperature ◽  
Hydration Reaction ◽  
Volume Deformation ◽  
Influence Of Temperature ◽  
Field Simulation ◽  
Influence Of Temperature On ◽  
The Difference

Aotugenous volume deformation is one of the influence factors of stress field of concrete structure. Generally, the influence of temperature on autogenous volume strain is not considered in calculation. In fact, the difference of internal and surface temperature of concrete structure can lead to different hydration reaction and different autogeneous volume deformation. In order to find out the effect of temperature difference on aotogenous volume deformation and stress field of concrete structure, a model is established and a corresponding example is given. The result shows that it is necessary to take temperature effect into consideration while calculate autogenous volume deformation in stress field simulation of concrete structure.

The effect of temperature on high-resolution TEM image contrast

1995 ◽  
Vol 53 ◽  
pp. 640-641
Author(s):  
T. Geipel ◽  
W. Mader ◽  
P. Pirouz
Keyword(s):  
Form Factor ◽  
Inelastic Scattering ◽  
Accurate Method ◽  
Waller Factor ◽  
Effect Of Temperature ◽  
Specimen Thickness ◽  
Influence Of Temperature ◽  
Debye Waller Factor ◽  
Influence Of Temperature On ◽  
Atomic Form Factor

Temperature affects both elastic and inelastic scattering of electrons in a crystal. The Debye-Waller factor, B, describes the influence of temperature on the elastic scattering of electrons, whereas the imaginary part of the (complex) atomic form factor, fc = fr + ifi, describes the influence of temperature on the inelastic scattering of electrons (i.e. absorption). In HRTEM simulations, two possible ways to include absorption are: (i) an approximate method in which absorption is described by a phenomenological constant, μ, i.e. fi; - μfr, with the real part of the atomic form factor, fr, obtained from Hartree-Fock calculations, (ii) a more accurate method in which the absorptive components, fi of the atomic form factor are explicitly calculated. In this contribution, the inclusion of both the Debye-Waller factor and absorption on HRTEM images of a (Oll)-oriented GaAs crystal are presented (using the EMS software.Fig. 1 shows the the amplitudes and phases of the dominant 111 beams as a function of the specimen thickness, t, for the cases when μ = 0 (i.e. no absorption, solid line) and μ = 0.1 (with absorption, dashed line).

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