scholarly journals Impact Energy and Angular Dependence of L X-ray Emission from a Thick Polycrystalline Tungsten Element Induced by 15–25 keV Electrons

Atoms ◽  
2020 ◽  
Vol 8 (4) ◽  
pp. 82
Author(s):  
Bhupendra Singh ◽  
Suman Prajapati ◽  
Bhartendu K. Singh ◽  
R. Shanker
Keyword(s):  
Angular Dependence ◽  
Impact Energy ◽  
Intensity Ratio ◽  
Incidence Angle ◽  
Angular Variation ◽  
Measured Intensity ◽  
Polycrystalline Tungsten ◽  
Simulation Results ◽  
The Impact ◽  
Good Agreement

The impact energy and angular dependence of L X-rays of a thick polycrystalline tungsten (W; atomic number, Z = 74) target induced by 15–25 keV electrons has been measured at different angles varying from 15° to 75° at intervals of 5° using a Si PIN photodiode detector. The variation of measured relative intensity of Ll, Lα, Lβ and Lγ characteristic lines as a function of incidence angle is found to be anisotropic and the measured variation compares well with the PENELOPE simulation results. The angular variation of intensity ratio of Ll/Lα and Lβ/Lα shows anisotropic distribution, whereas the angular variation of the Lγ/Lα ratio exhibits almost isotropic distribution within the uncertainty of measurements. These measured ratios are found to be in good agreement with Monte Carlo (MC) calculations. The measured intensity ratios of Lβ/Lα and Lγ/Lα at a given incidence angle show a linear dependence with impact energy and exhibit good agreement with simulation results; however, the measured intensity ratio of Ll/Lα shows a non-linear variation with the impact energy and yields poor agreement with theoretical calculations.

scholarly journals Measuring Hydrometeors Using a Precipitation Microphysical Characteristics Sensor: Sampling Effect of Different Bin Sizes on Drop Size Distribution Parameters

2018 ◽  
Vol 2018 ◽  
pp. 1-15 ◽  
Author(s):  
Xichuan Liu ◽  
Taichang Gao ◽  
Yuntao Hu ◽  
Xiaojian Shu
Keyword(s):  
Drop Size ◽  
Rain Rate ◽  
Monte Carlo Model ◽  
Rain Gauge ◽  
Sampling Schemes ◽  
Distribution Parameters ◽  
Optimum Sampling ◽  
Simulation Results ◽  
The Impact ◽  
Good Agreement

In order to improve the measurement of precipitation microphysical characteristics sensor (PMCS), the sampling process of raindrops by PMCS based on a particle-by-particle Monte-Carlo model was simulated to discuss the effect of different bin sizes on DSD measurement, and the optimum sampling bin sizes for PMCS were proposed based on the simulation results. The simulation results of five sampling schemes of bin sizes in four rain-rate categories show that the raw capture DSD has a significant fluctuation variation influenced by the capture probability, whereas the appropriate sampling bin size and width can reduce the impact of variation of raindrop number on DSD shape. A field measurement of a PMCS, an OTT PARSIVEL disdrometer, and a tipping bucket rain Gauge shows that the rain-rate and rainfall accumulations have good consistencies between PMCS, OTT, and Gauge; the DSD obtained by PMCS and OTT has a good agreement; the probability of N0, μ, and Λ shows that there is a good agreement between the Gamma parameters of PMCS and OTT; the fitted μ-Λ and Z-R relationship measured by PMCS is close to that measured by OTT, which validates the performance of PMCS on rain-rate, rainfall accumulation, and DSD related parameters.

The penetration and ricochet of ogive-nosed rigid projectiles obliquely impacting metallic targets

2021 ◽  
pp. 204141962110377
Author(s):  
Yaniv Vayig ◽  
Zvi Rosenberg
Keyword(s):  
Experimental Data ◽  
Numerical Simulations ◽  
Dynamic Pressure ◽  
Oblique Impacts ◽  
Simulation Results ◽  
The Impact ◽  
Penetration Depths ◽  
Resistance To Penetration ◽  
Good Agreement

A large number of 3D numerical simulations were performed in order to follow the trajectory changes of rigid CRH3 ogive-nosed projectiles, impacting semi-infinite metallic targets at various obliquities. These trajectory changes are shown to be related to the threshold ricochet angles of the projectile/target pairs. These threshold angles are the impact obliquities where the projectiles end up moving in a path parallel to the target’s face. They were found to depend on a non-dimensional entity which is equal to the ratio between the target’s resistance to penetration and the dynamic pressure exerted by the projectile upon impact. Good agreement was obtained by comparing simulation results for these trajectory changes with experimental data from several published works. In addition, numerically-based relations were derived for the penetration depths of these ogive-nosed projectiles at oblique impacts, which are shown to agree with the simulation results.

Pseudopotential calculations of elastic scattering of low-energy electrons (< 20 eV) from neon atoms

1992 ◽  
Vol 70 (5) ◽  
pp. 305-310 ◽  
Author(s):  
Y. Frongillo ◽  
B. Plenkiewicz ◽  
P. Plenkiewicz ◽  
J.-P. Jay-Gerin
Keyword(s):  
Elastic Scattering ◽  
Energy Range ◽  
Cross Sections ◽  
Impact Energy ◽  
Theoretical Data ◽  
Low Energy ◽  
Pseudopotential Calculations ◽  
Low Energy Electrons ◽  
The Impact ◽  
Good Agreement

Pseudopotential calculations of phase shifts, differential, total, and momentum-transfer cross sections for electrons elastically scattered from neon atoms are reported in the impact energy range 0–20 eV. The results are found to be in very good agreement with existing experimental and other theoretical data.

scholarly journals Impact of Dielectric Constant on Embedded Antenna Efficiency

2014 ◽  
Vol 2014 ◽  
pp. 1-6 ◽  
Author(s):  
Van Thuan Nguyen ◽  
Chang Won Jung
Keyword(s):  
Dielectric Constant ◽  
Human Body ◽  
Human Muscle ◽  
Radiation Efficiency ◽  
Liquid Environment ◽  
Antenna Efficiency ◽  
Embedded Antennas ◽  
Simulation Results ◽  
The Impact ◽  
Good Agreement

The impact of dielectric constant on radiation efficiency of embedded antenna located inside human body or another liquid environment is investigated both analytically and numerically. Our research is analysed and simulated at 403 MHz in the MedRadio band (401–406 MHz) and within a block of 2/3 human muscle phantom. Good agreement is achieved between analysis and simulation results. This work provides a guidance in selecting insulator for embedded antennas.

Mechanism Study on the Impact of Low Pressure Accumulator with Mechanical Mechanics to Hydraulic Impactor

2014 ◽  
Vol 908 ◽  
pp. 296-300
Author(s):  
Zhong Yi Cao ◽  
Xiang Yang Huang ◽  
Wan Rong Wu
Keyword(s):  
Model Calculation ◽  
Impact Energy ◽  
Simulation Models ◽  
Mathematic Model ◽  
Low Pressure ◽  
Small Degree ◽  
Simulation System ◽  
Mechanism Study ◽  
Simulation Results ◽  
The Impact

To investigate the impact of low pressure accumulator to the performance of hydraulic impactor, mathematic model of hydraulic impactor was established. By application of AMESim, The simulation models of hydraulic impactor with low pressure accumulator and hydraulic impactor without low pressure accumulator were obtained. After model calculation, the displacement, velocity of the piston and the return pressure were shown in figures. Rationality of the simulation system was verified by the compare between simulation results and experimental results. The simulation results show that low pressure accumulator can increase the impact energy and frequency of hydraulic impactor in a small degree and reduce the impact of return pressure significantly. Article provides theory basis for the designation of hydraulic impactor.

scholarly journals Effect of specimen bed on the material removal due to the repetitive single ball impacts

2019 ◽  
Vol 20 (4) ◽  
pp. 401
Author(s):  
Mehdi Akhondizadeh ◽  
Meysam Atashafrooz
Keyword(s):  
Mass Loss ◽  
Impact Energy ◽  
Material Removal ◽  
Incidence Angle ◽  
High Energy ◽  
Test Machine ◽  
Positive Role ◽  
Ball Impact ◽  
Bed Material ◽  
The Impact

Specimen wear due to the repetitive single ball impact is investigated experimentally by a drop test machine. Effect of the impact energy, incidence angle and bed material is studied. Specimen mass loss is measured after 1000 impacts. The crater dimension on the specimen surface is measured to indicate its correlation with the wear variation. Results show that the rubber bed has the undeniable positive role in decrement of the wear due to impact comparing with the steel bed. A relation between the energies which give the same wear, in both cases of the rubber and steel bed, is extracted. Results can be helpful in designing the appropriate bed where the medium and high energy impacts encouraged.

Simulation Studies on the Influence of Impact Velocity on the PELE Penetrated and Broken Reinforced Concrete

2013 ◽  
Vol 690-693 ◽  
pp. 3108-3111 ◽  
Author(s):  
Xiao Jun Ye ◽  
Zhong Hua Du ◽  
Chuan Hui Hu ◽  
Cheng Jun Song ◽  
Xiao Sheng
Keyword(s):  
Finite Element Method ◽  
Reinforced Concrete ◽  
Impact Velocity ◽  
Simulation Studies ◽  
Residual Velocity ◽  
Software Simulation ◽  
Definite Effect ◽  
Simulation Results ◽  
The Impact ◽  
Good Agreement

In order to study the effect of the impact velocity for the penetrator with enhanced lateral effect (PELE) penetrating reinforced concrete (RC) targets, penetration of PELE filled nylon against RC target using the different velocity is simulated by LS-DYNA finite element method software. Simulation shows that the impact velocity have definite effect on broken RC. On condition of PELE having penetrated target, with farther increase of impact velocity, the area of PELE broken RC on the direction of decrease firstly and augmentation thereafter, the residual velocity after penetrating target is less at the same time; Take into account validity of lateral effect and general launching condition, selecting the impact velocity at the range of 800 m/s-1300 m/s is suitable for PELE broken RC. The simulation results are in good agreement with those of the experiments.

Modeling of Tread Block Contact Mechanics Using Linear Viscoelastic Theory3

2008 ◽  
Vol 36 (3) ◽  
pp. 211-226 ◽  
Author(s):  
F. Liu ◽  
M. P. F. Sutcliffe ◽  
W. R. Graham
Keyword(s):  
High Speed ◽  
Slip Rate ◽  
Material Model ◽  
Contact Forces ◽  
Block Modeling ◽  
Rate Dependent ◽  
Linear Viscoelastic Material ◽  
Linear Viscoelastic ◽  
The Impact ◽  
Good Agreement

Abstract In an effort to understand the dynamic hub forces on road vehicles, an advanced free-rolling tire-model is being developed in which the tread blocks and tire belt are modeled separately. This paper presents the interim results for the tread block modeling. The finite element code ABAQUS/Explicit is used to predict the contact forces on the tread blocks based on a linear viscoelastic material model. Special attention is paid to investigating the forces on the tread blocks during the impact and release motions. A pressure and slip-rate-dependent frictional law is applied in the analysis. A simplified numerical model is also proposed where the tread blocks are discretized into linear viscoelastic spring elements. The results from both models are validated via experiments in a high-speed rolling test rig and found to be in good agreement.

Dynamic model for high-speed rotors based on their experimental characterization

2017 ◽  
Vol 2 (4) ◽  
pp. 25
Author(s):  
L. A. Montoya ◽  
E. E. Rodríguez ◽  
H. J. Zúñiga ◽  
I. Mejía
Keyword(s):  
Dynamic Model ◽  
High Speed ◽  
Natural Frequencies ◽  
Mode Shapes ◽  
Experimental Characterization ◽  
Rotating Systems ◽  
Computing Performance ◽  
The Impact ◽  
Stiffness Distribution ◽  
Good Agreement

Rotating systems components such as rotors, have dynamic characteristics that are of great importance to understand because they may cause failure of turbomachinery. Therefore, it is required to study a dynamic model to predict some vibration characteristics, in this case, the natural frequencies and mode shapes (both of free vibration) of a centrifugal compressor shaft. The peculiarity of the dynamic model proposed is that using frequency and displacements values obtained experimentally, it is possible to calculate the mass and stiffness distribution of the shaft, and then use these values to estimate the theoretical modal parameters. The natural frequencies and mode shapes of the shaft were obtained with experimental modal analysis by using the impact test. The results predicted by the model are in good agreement with the experimental test. The model is also flexible with other geometries and has a great time and computing performance, which can be evaluated with respect to other commercial software in the future.

scholarly journals A New Method to Determine the Impact of Individual Field Quantities on Cycle-to-Cycle Variations in a Spark-Ignited Gas Engine

Energies ◽  
2021 ◽  
Vol 14 (14) ◽  
pp. 4136
Author(s):  
Clemens Gößnitzer ◽  
Shawn Givler
Keyword(s):  
Kinetic Energy ◽  
Flow Field ◽  
Turbulent Kinetic Energy ◽  
Negative Impact ◽  
Operating Conditions ◽  
Engine Operation ◽  
Gas Engine ◽  
Cycle Simulation ◽  
Simulation Results ◽  
The Impact

Cycle-to-cycle variations (CCV) in spark-ignited (SI) engines impose performance limitations and in the extreme limit can lead to very strong, potentially damaging cycles. Thus, CCV force sub-optimal engine operating conditions. A deeper understanding of CCV is key to enabling control strategies, improving engine design and reducing the negative impact of CCV on engine operation. This paper presents a new simulation strategy which allows investigation of the impact of individual physical quantities (e.g., flow field or turbulence quantities) on CCV separately. As a first step, multi-cycle unsteady Reynolds-averaged Navier–Stokes (uRANS) computational fluid dynamics (CFD) simulations of a spark-ignited natural gas engine are performed. For each cycle, simulation results just prior to each spark timing are taken. Next, simulation results from different cycles are combined: one quantity, e.g., the flow field, is extracted from a snapshot of one given cycle, and all other quantities are taken from a snapshot from a different cycle. Such a combination yields a new snapshot. With the combined snapshot, the simulation is continued until the end of combustion. The results obtained with combined snapshots show that the velocity field seems to have the highest impact on CCV. Turbulence intensity, quantified by the turbulent kinetic energy and turbulent kinetic energy dissipation rate, has a similar value for all snapshots. Thus, their impact on CCV is small compared to the flow field. This novel methodology is very flexible and allows investigation of the sources of CCV which have been difficult to investigate in the past.

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