Analysis of the Impact of Plasma Sheath on GPS Antenna

The electromagnetic simulation software CST was used to analyze the effects of reentry plasma sheath on the GPS navigation antenna. The Impedance and radiation characteristics of antenna were studied on condition that the antenna was coated with uniform and nonuniform electron density distribution plasma sheath respectively. The results show that, the antenna coated with the uniform plasma sheath, the plasma electron density increasing, the antenna operating frequency moves to high-frequency and that the directivity decreases as well; when the antenna was coated with nonuniform plasma, with the higher electron peak density of plasma sheath, besides that the operating frequency also moves to high-frequency, the bandwidth stretches wide and the return loss reduces; the antenna radiation pattern distorts seriously at the electron peak density of 1018m-3.

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The Simulation Analysis of the High Speed Switch Valve Control the Cartridge Valve Based on AMEsim

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.971-973.827 ◽

2014 ◽

Vol 971-973 ◽

pp. 827-832

Author(s):

Yan Jin Qin ◽

Zhang Yong Wu ◽

Zi Yong Mo ◽

Xian Wang ◽

Juan Wang

Keyword(s):

Duty Cycle ◽

High Frequency ◽

High Speed ◽

Simulation Analysis ◽

Simulation Software ◽

Pulse Width Modulated ◽

Working Principle ◽

The Impact ◽

The Mathematical Model ◽

Valve Control

To establish the mathematical model of the system of high speed switch valve control the cartridge valve based on analyzing the working principle of the system,and then to analyze the impact of selecting different input signal of high speed solenoid valve and different duty cycle of PWM pulse width modulated signal through simulation software AMSEsim. The results obtained in the high-frequency performance is not very satisfactory, but in the low signal and moderate duty cycle, high-speed switch valve can be good linear control of the cartridge valve.

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The Impact of Noise Expose on the Hearing Threshold Extended High Frequency

Korean Journal of Occupational and Environmental Medicine ◽

10.35371/kjoem.2008.20.2.81 ◽

2008 ◽

Vol 20 (2) ◽

pp. 81 ◽

Cited By ~ 1

Author(s):

Nam Jeong Kim ◽

Joong Keun Kwon ◽

Ji Ho Lee

Keyword(s):

High Frequency ◽

Hearing Threshold ◽

The Impact

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Global Algorithmic Capital Markets

10.1093/oso/9780198829461.001.0001 ◽

2018 ◽

Cited By ~ 2

Keyword(s):

Public Policy ◽

Capital Markets ◽

Systemic Risk ◽

High Frequency ◽

Investor Protection ◽

High Frequency Trading ◽

Market Making ◽

Market Governance ◽

Policy Objectives ◽

The Impact

This book illustrates and assesses the dramatic recent transformations in capital markets worldwide and the impact of those transformations. ‘Market making’ by humans in centralized markets has been replaced by supercomputers and algorithmic high frequency trading operating in often highly fragmented markets. How do recent market changes impact on core public policy objectives such as investor protection, reduction of systemic risk, fairness, efficiency, and transparency in markets? The operation and health of capital markets affect all of us and have profound implications for equality and justice in society. This unique set of chapters by leading scholars, industry insiders, and regulators sheds light on these and related questions and discusses ways to strengthen market governance for the benefit of society at large.

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Crisis Management in Higher Education in the Time of Covid-19: The Case of Actor Training

Education Sciences ◽

10.3390/educsci11030132 ◽

2021 ◽

Vol 11 (3) ◽

pp. 132

Author(s):

Anna McNamara

Keyword(s):

Higher Education ◽

Crisis Management ◽

High Frequency ◽

High Reliability ◽

Actor Training ◽

Management Actions ◽

The Usa ◽

The Uk ◽

The Impact ◽

High Frequency Words

The impact of Covid-19 placed Higher Education leadership in a state of crisis management, where decision making had to be swift and impactful. This research draws on ethea of mindfulness, actor training techniques, referencing high-reliability organisations (HRO). Interviews conducted by the author with three leaders of actor training conservatoires in Higher Education institutions in Australia, the UK and the USA reflect on crisis management actions taken in response to the impact of Covid-19 on their sector, from which high-frequency words are identified and grouped thematically. Reflecting on these high-frequency words and the thematic grouping, a model of mindful leadership is proposed as a positive tool that may enable those in leadership to recognise and respond efficiently to wider structural frailties within Higher Education, with reference to the capacity of leaders to operate with increased mindfulness, enabling a more resilient organisation that unlocks the locus of control.

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Experimental and Numerical Study of Fracture Behavior of Rock-Like Material Specimens with Single Pre-Set Joint under Dynamic Loading

Materials ◽

10.3390/ma14102690 ◽

2021 ◽

Vol 14 (10) ◽

pp. 2690

Author(s):

Bo Pan ◽

Xuguang Wang ◽

Zhenyang Xu ◽

Lianjun Guo ◽

Xuesong Wang

Keyword(s):

Crack Initiation ◽

Crack Propagation ◽

Joint Angle ◽

Simulation Software ◽

Dissipated Energy ◽

Energy Structure ◽

Joint Angles ◽

Crack Penetration ◽

Before And After ◽

The Impact

The Split Hopkinson Pressure Bar (SHPB) is an apparatus for testing the dynamic stress-strain response of the cement mortar specimen with pre-set joints at different angles to explore the influence of joint attitudes of underground rock engineering on the failure characteristics of rock mass structure. The nuclear magnetic resonance (NMR) has also been used to measure the pore distribution and internal cracks of the specimen before and after the testing. In combination with numerical analysis, the paper systematically discusses the influence of joint angles on the failure mode of rock-like materials from three aspects of energy dissipation, microscopic damage, and stress field characteristics. The result indicates that the impact energy structure of the SHPB is greatly affected by the pre-set joint angle of the specimen. With the joint angle increasing, the proportion of reflected energy moves in fluctuation, while the ratio of transmitted energy to dissipated energy varies from one to the other. NMR analysis reveals the structural variation of the pores in those cement specimens before and after the impact. Crack propagation direction is correlated with pre-set joint angles of the specimens. With the increase of the pre-set joint angles, the crack initiation angle decreases gradually. When the joint angles are around 30°–75°, the specimens develop obvious cracks. The crushing process of the specimens is simulated by LS-DYNA software. It is concluded that the stresses at the crack initiation time are concentrated between 20 and 40 MPa. The instantaneous stress curve first increases and then decreases with crack propagation, peaking at different times under various joint angles; but most of them occur when the crack penetration ratio reaches 80–90%. With the increment of joint angles in specimens through the simulation software, the changing trend of peak stress is consistent with the test results.

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A Low-Profile HF Meandered Dipole Antenna with a Ferrite-Loaded Artificial Magnetic Conductor

Applied Sciences ◽

10.3390/app11052237 ◽

2021 ◽

Vol 11 (5) ◽

pp. 2237

Author(s):

Oh Heon Kwon ◽

Won Bin Park ◽

Juho Yun ◽

Hong Jun Lim ◽

Keum Cheol Hwang

Keyword(s):

High Frequency ◽

Dipole Antenna ◽

Unit Cell ◽

Operating Frequency ◽

High Permeability ◽

Magnetic Conductor ◽

Artificial Magnetic Conductor ◽

Low Profile ◽

Compact Size ◽

Binary Genetic Algorithm

In this paper, a low-profile HF (high-frequency) meandered dipole antenna with a ferrite-loaded artificial magnetic conductor (AMC) is proposed. To operate in the HF band while retaining a compact size, ferrite with high permeability is applied to the unit cell of the AMC. The operating frequency bandwidth of the designed unit cell of the AMC is 1.89:1 (19–36 MHz). Thereafter, a meandered dipole antenna is designed by implementing a binary genetic algorithm and is combined with the AMC. The overall size of the designed antenna is 0.06×0.06×0.002 λ3 at the lowest operating frequency. The proposed dipole antenna with a ferrite-loaded AMC is fabricated and measured. The measured VSWR bandwidth (<3) covers 20–30 MHz on the HF band. To confirm the performance of the antenna, a reference monopole antenna which operates on the HF band was selected, and the measured receiving power is compared with the result of the proposed antenna with the AMC.

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A simplified iterative approach for testing the pulse derailment of light rail vehicles across a viaduct to near-fault earthquake scenarios

Proceedings of the Institution of Mechanical Engineers Part F Journal of Rail and Rapid Transit ◽

10.1177/0954409720987410 ◽

2021 ◽

pp. 095440972098741

Author(s):

Ling-Kun Chen ◽

Peng Liu ◽

Li-Ming Zhu ◽

Jing-Bo Ding ◽

Yu-Lin Feng ◽

...

Keyword(s):

Ground Motions ◽

Simulation Software ◽

Light Rail ◽

Rail Transit ◽

Light Rail Transit ◽

Seismic Responses ◽

Near Fault ◽

Rail Vehicle ◽

Pulse Type ◽

The Impact

Near-fault (NF) earthquakes cause severe bridge damage, particularly urban bridges subjected to light rail transit (LRT), which could affect the safety of the light rail transit vehicle (“light rail vehicle” or “LRV” for short). Now when a variety of studies on the fault fracture effect on the working protection of LRVs are available for the study of cars subjected to far-reaching soil motion (FFGMs), further examination is appropriate. For the first time, this paper introduced the LRV derailment mechanism caused by pulse-type near-fault ground motions (NFGMs), suggesting the concept of pulse derailment. The effects of near-fault ground motions (NFGMs) are included in an available numerical process developed for the LRV analysis of the VBI system. A simplified iterative algorithm is proposed to assess the stability and nonlinear seismic response of an LRV-reinforced concrete (RC) viaduct (LRVBRCV) system to a long-period NFGMs using the dynamic substructure method (DSM). Furthermore, a computer simulation software was developed to compute the nonlinear seismic responses of the VBI system to pulse-type NFGMs, non-pulse-type NFGMs, and FFGMs named Dynamic Interaction Analysis for Light-Rail-Vehicle Bridge System (DIALRVBS). The nonlinear bridge seismic reaction determines the impact of pulses on lateral peak earth acceleration (Ap) and lateral peak land (Vp) ratios. The analysis results quantify the effects of pulse-type NFGMs seismic responses on the LRV operations' safety. In contrast with the pulse-type non-pulse NFGMs and FFGMs, this article's research shows that pulse-type NFGM derail trains primarily via the transverse velocity pulse effect. Hence, this study's results and the proposed method can improve the LRT bridges' seismic designs.

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