Characteristics of defect states in periodic railway track structure

To overcome the ill-conditioned matrix problem of the traditional transfer matrix method, the Floquet transform method and supercell technology are used to study the defect states of the periodic track structure. By solving the equations of the supercell directly, the propagation characteristics of elastic waves in the track structure with defects are analyzed. The existence of defects destroys the periodicity of track structure, thus resulting in the formation of defect states within the band gaps. Moreover, the elastic wave is localized near the defect position at the frequency of the defect state. The formation mechanism of the defect state in track structure can be explained by the local resonance at the defect. With the expansion of the defect range, the number of local resonance modes that can be formed near the defect increases, thus generating multiple defect states. Furthermore, the defect state enhances the vibration of the structure adjacent to the defect. Therefore, the vibration transmission coefficient in a finite-length range can be used to detect the defect characteristics in the track structure, and the defect degree can be evaluated by the peak frequency of the vibration transmission coefficient within the band gap.

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Deformation Law and Control Limit of CRTSIII Slab Track under Subgrade Frost Heave

Applied Sciences ◽

10.3390/app11083520 ◽

2021 ◽

Vol 11 (8) ◽

pp. 3520

Author(s):

Xiaopei Cai ◽

Qian Zhang ◽

Yanrong Zhang ◽

Qihao Wang ◽

Bicheng Luo ◽

...

Keyword(s):

High Speed ◽

Base Plate ◽

Element Model ◽

Middle Part ◽

Railway Track ◽

Frost Heave ◽

Track Structure ◽

Slab Track ◽

Plastic Damage ◽

Track Irregularity

In order to find out the influence of subgrade frost heave on the deformation of track structure and track irregularity of high-speed railways, a nonlinear damage finite element model for China Railway Track System III (CRTSIII) slab track subgrade was established based on the constitutive theory of concrete plastic damage. The analysis of track structure deformation under different subgrade frost heave conditions was focused on, and amplitude the limit of subgrade frost heave was put forward according to the characteristics of interlayer seams. This work is expected to provide guidance for design and construction. Subgrade frost heave was found to cause cosine-type irregularities of rails and the interlayer seams in the track structure, and the displacement in lower foundation mapping to rail surfaces increased. When frost heave occured in the middle part of the track slab, it caused the greatest amount of track irregularity, resulting in a longer and higher seam. Along with the increase in frost heave amplitude, the length of the seam increased linearly whilst its height increased nonlinearly. When the frost heave amplitude reached 35 mm, cracks appeared along the transverse direction of the upper concrete surface on the base plate due to plastic damage; consequently, the base plate started to bend, which reduced interlayer seams. Based on the critical value of track structures’ interlayer seams under different frost heave conditions, four control limits of subgrade frost heave at different levels of frost heave amplitude/wavelength were obtained.

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Modelling a temperature regime of a railway track structure and its comparison with the results of experimental measurements

Computers in Railways XIV ◽

10.2495/cr140201 ◽

2014 ◽

Author(s):

S. Hodas

Keyword(s):

Temperature Regime ◽

Railway Track ◽

Track Structure ◽

Experimental Measurements

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PRELIMINARY RESULTS AND CONCLUSIONS FROM THE EXPERIMENTAL MONITORING OF THERMAL REGIME OF RAILWAY TRACK STRUCTURE

WIT Transactions on State-of-the-art in Science and Engineering - Railway Engineering, Design and Operation ◽

10.2495/tdi-v1-n3-529-539/023 ◽

2016 ◽

pp. 223-233

Author(s):

L. IŽVOLT ◽

P. DOBEŠ ◽

M. PITOŇÁK

Keyword(s):

Thermal Regime ◽

Railway Track ◽

Track Structure ◽

Preliminary Results

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Insights on the impact of photophysical processes and defect states evolution on the emission properties of surface-modified ZnO nanoplates for application in photocatalysis and hybrid LEDs

Physical Chemistry Chemical Physics ◽

10.1039/d1cp05110e ◽

2021 ◽

Author(s):

Dhritiman Banerjee ◽

Payal Banerjee ◽

Asit Kumar Kar

Keyword(s):

Zinc Oxide ◽

Optical Properties ◽

Surface Modification ◽

Defect State ◽

Defect States ◽

Emission Properties ◽

Photophysical Processes ◽

State Densities ◽

Surface Modified ◽

The Impact

The effects of surface modification on the defect state densities, optical properties, photocatalytic and quantum efficiencies of zinc oxide (ZnO) nanoplates have been studied in this work. Here, the aim...

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Reducing of negative heavy axle load impact on the railway track structure

10.1063/5.0063962 ◽

2021 ◽

Author(s):

Alexey Kolos ◽

Andrei Petriaev ◽

Irina Kolos ◽

Anastasia Konon

Keyword(s):

Railway Track ◽

Track Structure ◽

Load Impact

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Experimental monitoring and numerical modeling of thermal regime of railway track structure - preliminary results and conclusions

Canadian Journal of Civil Engineering ◽

10.1139/cjce-2016-0199 ◽

2017 ◽

Vol 44 (4) ◽

pp. xxx-xxx

Keyword(s):

Numerical Modeling ◽

Thermal Regime ◽

Railway Track ◽

Track Structure ◽

Preliminary Results

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The Nature of Native and Light Induced Defect States in i-layers of High Quality a-Si:H Solar Cells Derived from Dark Forward-Bias Current-Voltage Characteristics

MRS Proceedings ◽

10.1557/proc-862-a11.4 ◽

2005 ◽

Vol 862 ◽

Cited By ~ 4

Author(s):

J. Deng ◽

M. L. Albert ◽

J. M. Pearce ◽

R. W. Collins ◽

C. R. Wronski

Keyword(s):

Solar Cells ◽

Forward Bias ◽

Bias Current ◽

Defect State ◽

Defect States ◽

High Quality ◽

Hydrogen Dilution ◽

Current Voltage ◽

Current Voltage Characteristics ◽

Gap States

AbstractResults are presented on the defect state distributions in intrinsic a-Si:H layers with and without hydrogen dilution in p-i-n solar cells obtained directly from the analysis of dark forwardbias current-voltage (JD-V) characteristics. It is shown that there are distinct differences in the distributions of both native and light induced defect states between the two types of i-layers. Computer simulations using these distributions are presented which show excellent agreement with the experimental results not only for the JD-V but more importantly for the bias dependent differential diode quality factor n(V) characteristics. Results are also presented on the nature of the gap states and their evolution with light induced degradation as well as their effects on the performance and stability of high quality a-Si:H solar cells.

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Experimental Study of the Influence of Extremely Repeated Thermal Loading on a Ballastless Slab Track-Bridge Structure

Applied Sciences ◽

10.3390/app10020461 ◽

2020 ◽

Vol 10 (2) ◽

pp. 461 ◽

Cited By ~ 1

Author(s):

Lingyu Zhou ◽

Tianyu Wei ◽

Guangchao Zhang ◽

Yingying Zhang ◽

Mahunon Akim Djibril Gildas ◽

...

Keyword(s):

Thermal Loading ◽

Reduction Rate ◽

Railway Track ◽

Track Structure ◽

Structural System ◽

Loading Test ◽

Slab Track ◽

Loading Tests ◽

Three Stages ◽

Track Bridge

To study the initiation and expansion of the interlayer gap of the China Railway Track System Type II (CRTS-II) ballastless slab track structure under the action of repeated thermal loading as well as the influence of the interlayer gap on the displacement, strain and stiffness of the track structure, a 1/4 scale three-span ballastless slab track simply supported bridge structural system specimen was developed and 18 cycles of extremely thermal loading tests were carried out. Static loading tests were carried out before and after the repeated thermal loading test and the effects of the repeated temperature loading on the mechanical properties of the structural system were analyzed. The test results show that under repeated temperature loading, there is a gap between the track slab and cement emulsified asphalt (CA) mortar near the fixed end section of the beam (close to the shear slots). The interlayer gap gradually expands to the mid-span section in a “stepped” shape in three stages: initiation, expansion and stabilization. Under the same temperature load, the camber of the concrete box beam decreases gradually while that of the track structure increases gradually with the increase of the interlayer gap length. During the three stages of interlayer gap development, the track structure stiffness degrades gradually, and the fastest reduction rate during the expansion stage. At the end of the 18th cycle of thermal loading, a degradation of 14.96% and 2.52% is observed in the stiffness of the track structure and that of the ballastless track-bridge structural system, respectively.

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Electrical Defect State Distribution in Single Crystal ZnO Schottky Barrier Diodes

Coatings ◽

10.3390/coatings10030206 ◽

2020 ◽

Vol 10 (3) ◽

pp. 206

Author(s):

Jinhee Park ◽

You Seung Rim ◽

Pradeep Senanayake ◽

Jiechen Wu ◽

Dwight Streit

Keyword(s):

Single Crystal ◽

Band Gap ◽

Schottky Barrier ◽

Deep Level ◽

Depletion Region ◽

Intrinsic Defect ◽

Defect State ◽

Schottky Barrier Diodes ◽

Defect States ◽

State Distribution

The characterization of defect states in a hydrothermally grown single crystal of ZnO was performed using deep-level transient spectroscopy in the temperature range of 77–340 K. The native intrinsic defect energy level within the ZnO band gap occurred in the depletion region of ZnO Schottky barrier diodes. A major defect level was observed, with a thermal activation energy of 0.27 eV (E3) within the defect state distribution from 0.1 to 0.57 eV below the conduction band minimum. We confirmed the maximum defect concentration to be 3.66 × 1016 cm−3 at 0.27 eV (E3). As a result, we clearly confirmed the distribution of density of defect states in the ZnO band gap.

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