Radiation‐driven inertial fusion targets for implosion experiments: Theoretical analysis and numerical simulations

1991 ◽  
Vol 3 (7) ◽  
pp. 1717-1727 ◽  
Author(s):  
N. A. Tahir ◽  
R. C. Arnold
Keyword(s):  
Theoretical Analysis ◽  
Numerical Simulations ◽  
Inertial Fusion

scholarly journals Theoretical Analysis and Design of an Innovative Coil Structure for Transcranial Magnetic Stimulation

2021 ◽  
Vol 11 (4) ◽  
pp. 1960
Author(s):  
Naming Zhang ◽  
Ziang Wang ◽  
Jinhua Shi ◽  
Shuya Ning ◽  
Yukuo Zhang ◽  
...  
Keyword(s):  
Electromagnetic Field ◽  
Transcranial Magnetic Stimulation ◽  
Theoretical Analysis ◽  
Numerical Simulations ◽  
Magnetic Stimulation ◽  
Influential Factors ◽  
Intersection Angle ◽  
Electromagnetic Field Distribution ◽  
Analysis And Design ◽  
Coil Structure

Previous research showed that pulsed functional magnetic stimulation can activate brain tissue with optimum intensity and frequency. Conventional stimulation coils are always set as a figure-8 type or Helmholtz. However, the magnetic fields generated by these coils are uniform around the target, and their magnetic stimulation performance still needs improvement. In this paper, a novel type of stimulation coil is proposed to shrink the irritative zone and strengthen the stimulation intensity. Furthermore, the electromagnetic field distribution is calculated and measured. Based on numerical simulations, the proposed coil is compared to traditional coil types. Moreover, the influential factors, such as the diameter and the intersection angle, are also analyzed. It was demonstrated that the proposed coil has a better performance in comparison with the figure-8 coil. Thus, this work suggests a new way to design stimulation coils for transcranial magnetic stimulation.

Mathematical Model Establishment and Analysis on the Pipe Deformation under External Pressure with the Ovality

2013 ◽  
Vol 760-762 ◽  
pp. 2263-2266
Author(s):  
Kang Yong ◽  
Wei Chen
Keyword(s):  
Mathematical Model ◽  
Theoretical Analysis ◽  
Yield Strength ◽  
Residual Stresses ◽  
Numerical Simulations ◽  
Significant Influence ◽  
External Pressure ◽  
Pipe Diameter ◽  
Axial Loads ◽  
The Stability

Beside the residual stresses and axial loads, other factors of pipe like ovality, moment could also bring a significant influence on pipe deformation under external pressure. The Standard of API-5C3 has discussed the influences of deformation caused by yield strength of pipe, pipe diameter and pipe thickness, but the factor of ovality degree is not included. Experiments and numerical simulations show that with the increasing of pipe ovality degree, the anti-deformation capability under external pressure will become lower, and ovality affecting the stability of pipe shape under external pressure is significant. So it could be a path to find out the mechanics relationship between ovality and pipe deformation under external pressure by the methods of numerical simulations and theoretical analysis.

An Alternative Carcass Design to Prevent Flow-Induced Pulsations in Flexibles

2021 ◽  
Author(s):  
N. González Díez ◽  
S. P. C. Belfroid ◽  
T. Iversen Solfeldt ◽  
C. Kristiansen
Keyword(s):  
Pressure Drop ◽  
Theoretical Analysis ◽  
Numerical Simulations ◽  
Steel Strip ◽  
Point Of View ◽  
Theoretical Point ◽  
Adjacent Structures ◽  
Operational Constraints ◽  
Short Time ◽  
Fatigue Failures

Abstract Flow-induced pulsations (FLIP) are pressure oscillations generated inside of flexibles used in dry gas applications that can cause unacceptable vibration levels and eventually failure of equipment. Because of the design of inner layer of the flexibles, the carcass, the frequency of the pulsations is high, potentially leading to fatigue failures of adjacent structures in a relatively short time. The traditional carcass is made of a steel strip formed into an interlocked s-shape in a series of preforming and winding steps. To enable bending of the pipe, gaps are present between each winding with a shape that can cause FLIP. The gaps can be reduced, and the profiles optimized, but they will always be able to generate FLIP at a certain gas velocity. To remove the risk of FLIP in dry gas projects and ensure that operator does not get operational constraints, an alternative carcass design has been developed. This is essentially a conventional agraff carcass but with an additional cover strip to close the gap, making the resulting carcass nearly smooth bore in nature. With a smooth bore this carcass can be used for flexibles which have a risk of FLIP or to produce pipes with a lower internal roughness. This alternative design can be manufactured and can therefore build on the large manufacturing and design experience of the traditional strip carcass. This alternative carcass technology is to undergo a full qualification process, in which the risk of flow induced pulsations is an essential component. With the investigated alternative carcass design, the cavities present in the traditional agraff designs are covered. It is expected that the risk due to the appearance of FLIP is therefore eliminated. Theoretical analysis, numerical simulations and scaled experiments are used to explore the risk for the alternative technology to create FLIP. The theoretical analysis is based on existing knowledge and literature. The numerical simulations and scaled tests are done to generate direct evidence for the end statements resulting from the qualification process. Numerical simulations follow the power balance method presented by the same authors in earlier papers. The same applies to the techniques used for the scaled tests. The main outcome of the qualification presented here are the pressure drop performance and the anti-FLIP capabilities of the design. The new design performs significantly better than the nominal design carcass for the same purpose. The pressure drop coefficients found are close to those expected for a normal, non-corrugated pipe, and thus the recommendation given by the API 17J standard does not apply to this design. The pressure drop coefficient is dependent on the installation direction of the flexible with respect to the flow. No signs of FLIP are found for the nominal design of the investigated carcass technology. This is the case for either installation direction. This is explained from a theoretical point of view, but also numerical and experimental evidence are provided.

Theoretical analysis and numerical simulations of turbulent jets in a wave environment

2020 ◽  
Vol 32 (3) ◽  
pp. 035105 ◽  
Author(s):  
Sara Barile ◽  
Diana De Padova ◽  
Michele Mossa ◽  
Stefano Sibilla
Keyword(s):  
Theoretical Analysis ◽  
Numerical Simulations ◽  
Turbulent Jets

Control of amplitude death by coupling range in a network of fractional-order oscillators

2020 ◽  
Vol 34 (31) ◽  
pp. 2050303
Author(s):  
Rui Xiao ◽  
Zhongkui Sun
Keyword(s):  
Theoretical Analysis ◽  
Numerical Simulations ◽  
Fractional Order ◽  
Coupling Strength ◽  
Low Frequency ◽  
System Size ◽  
Coupled Systems ◽  
Amplitude Death ◽  
Function Relationship ◽  
The Relationship

We investigate the oscillating dynamics in a ring of network of nonlocally delay-coupled fractional-order Stuart-Landau oscillators. It is concluded that with the increasing of coupling range, the structures of death islands go from richness to simplistic, nevertheless, the area of amplitude death (AD) state is expanded along coupling delay and coupling strength directions. The increased coupling range can prompt the coupled systems with low frequency to occur AD. When system size varies, the area of death islands changes periodically, and the linear function relationship between periodic length and coupling range can be deduced. Thus, one can modulate the oscillating dynamics by adjusting the relationship between coupling range and system size. Furthermore, the results of numerical simulations are consistent with theoretical analysis.

Study of Liquid-Metal Based Heating Method for Temperature Gradient Focusing Purpose

2013 ◽  
Vol 135 (9) ◽  
Author(s):  
M. Gao ◽  
L. Gui ◽  
J. Liu
Keyword(s):  
Optimal Design ◽  
Temperature Gradient ◽  
Liquid Metal ◽  
Theoretical Analysis ◽  
Numerical Simulations ◽  
Microfluidic Channels ◽  
Heating Method ◽  
Electrical Heater ◽  
Temperature Gradient Focusing ◽  
A New Technique

Temperature gradient focusing (TGF) is a highly efficient focusing technique for the concentration and separation of charged analytes in microfluidic channels. The design of an appropriate temperature gradient is very important for the focusing efficiency. In this study, we proposed a new technique to generate the temperature gradient. This technique utilizes a microchannel filled with liquid-metal as an electrical heater in a microfluidic chip. By applying an electric current, the liquid-metal heater generates Joule heat, forming the temperature gradient in the microchannel. To optimize the temperature gradient and find out the optimal design for the TGF chip, numerical simulations on four typical designs were studied. The results showed that design 1 can provide a best focusing method, which has the largest temperature gradient. For this best design, the temperature is almost linearly distributed along the focusing microchannel. The numerical simulations were then validated both theoretically and experimentally. The following experiment and theoretical analysis on the best design also provide a useful guidance for designing and fabricating the liquid-metal based TGF microchip.

Theoretical Analysis of a Reactive Reinforcement Method for Cylindrical Explosion-Containment Vessels

2014 ◽  
Vol 137 (1) ◽  
Author(s):  
Sui Yaguang ◽  
Zhang Dezhi ◽  
Tang Shiying ◽  
Li Jie ◽  
Lin Qizhao
Keyword(s):  
Shock Wave ◽  
Theoretical Analysis ◽  
Plastic Strain ◽  
Numerical Simulations ◽  
Circumferential Strain ◽  
Theoretical Calculations ◽  
Practical Application ◽  
Related Research ◽  
Explosion Loading ◽  
Approximate Expressions

A method for cylindrical explosion-containment vessels was presented, which used symmetrical implosion loading cooperating with the vessels to control the out-explosion loading, increasing the anti-explosion ability of explosion-containment vessels. In this study, theoretical analysis was developed first and response of cylindrical vessels loaded with implosion and out-explosion was discussed. Approximate expressions for final circumferential strain were obtained. Comparison between the theoretical calculations and the numerical simulations showed that the proposed method could effectively reduce the plastic strain of cylindrical explosion-containment vessels. The theoretical analysis introduced in this study can provide reference for related research. In addition, problems such as spall and defense of shock wave need to be solved before the presented method could be carried out in practical application.

The phenomenon of super energy flows in the anisotropic left-handed material

Open Physics ◽  
2013 ◽  
Vol 11 (1) ◽  
Author(s):  
Bai Xu ◽  
Guan Yu ◽  
Li Xia ◽  
Zhi Wang
Keyword(s):  
Theoretical Analysis ◽  
Numerical Simulations ◽  
Parallel Plate ◽  
Average Power ◽  
Electromagnetic Parameters ◽  
Left Handed ◽  
Energy Flows ◽  
Parallel Plate Waveguide ◽  
Time Average

AbstractThe super energy flows generated and transmitted have been investigated in a parallel-plate waveguide, which is filled with air and the anisotropic left-handed materials. Theoretical analysis and numerical simulations show that the propagation modes of the anisotropic super waveguide are consistent with those of the isotropic waveguides [1–3]. They also show that the loss of electromagnetic parameters size of waveguide will influence the amplitude of time-average power flows.

scholarly journals Theoretical Study and Optimization of the Biochemical Reaction Process by Means of Feedback Control Strategy

2013 ◽  
Vol 2013 ◽  
pp. 1-13 ◽  
Author(s):  
Kaibiao Sun ◽  
Andrzej Kasperski ◽  
Yuan Tian
Keyword(s):  
Mathematical Model ◽  
Feedback Control ◽  
Theoretical Analysis ◽  
Numerical Simulations ◽  
Control Strategy ◽  
Theoretical Study ◽  
Biomass Productivity ◽  
Reaction Process ◽  
Biochemical Reaction ◽  
Feedback Control Strategy

The aim of this work is to present a theoretical analysis and optimization of a biochemical reaction process by means of feedback control strategy. To begin with, a mathematical model of the biochemical reaction process with feedback control is formulated. Then, based on the formulated model, the analysis of system's dynamics is presented. The optimization of the bioprocess is carried out, in order to achieve maximal biomass productivity. It is shown that during the optimization, the bioprocess with impulse effects loses the possibility of synchronization and strives for a simple continuous bioprocess. The analytical results presented in the work are validated by numerical simulations for the Tessier kinetics model.

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