scholarly journals Developments in GPR Based NDT for Ballastless Track of High-Speed Railways

2020 ◽  
Author(s):  
Xiaoting Xiao ◽  
Guiyun Tian ◽  
Dong Liu ◽  
Mark Robinson ◽  
Anthony Gallagher
Keyword(s):  
Concrete Structure ◽  
High Speed ◽  
Nondestructive Method ◽  
Experimental Results ◽  
Significant Challenge ◽  
The Past ◽  
Ballastless Track ◽  
The World ◽  
Network Analyser ◽  
Ground Penetrating

For the past decades, ballastless track has been developed and used successfully throughout the world. Due to the multi-layer concrete structure of a ballastless track, timely detection of problems becomes a significant challenge. Ground Penetrating Radar (GPR), as an effective nondestructive method, has been applied to ballastless track in the last ten years. This paper reviews the state-of-the-art of GPR for the ballastless track. The challenges and problems are highlighted and discussed. A Vector Network Analyser (VNA) based stepped-frequency GPR system is considered for the problems and detection requirements. The experimental results show that the proposed system can detect narrow cracks in the depth up to 50cm.

scholarly journals WebRTC - Realtime Communication for the Open Web Platform

Queue ◽  
2021 ◽  
Vol 19 (1) ◽  
pp. 77-93
Author(s):  
Niklas Blum ◽  
Serge Lachapelle ◽  
Harald Alvestrand
Keyword(s):  
High Speed ◽  
Network Access ◽  
The Past ◽  
Human Contact ◽  
High Speed Network ◽  
The World ◽  
Web Platform

In this time of pandemic, the world has turned to Internet-based, RTC (realtime communication) as never before. The number of RTC products has, over the past decade, exploded in large part because of cheaper high-speed network access and more powerful devices, but also because of an open, royalty-free platform called WebRTC. WebRTC is growing from enabling useful experiences to being essential in allowing billions to continue their work and education, and keep vital human contact during a pandemic. The opportunities and impact that lie ahead for WebRTC are intriguing indeed.

The Past of the Future of Computation

2018 ◽  
Author(s):  
James A. Anderson
Keyword(s):  
Artificial Intelligence ◽  
High Speed ◽  
The Other ◽  
Cognitive Tasks ◽  
Cognitive Tool ◽  
The Past ◽  
The World ◽  
The Future ◽  
Simple Step ◽  
A Current

Hand axes, language, and computers are tools that increase our ability to deal with the world. Computing is a cognitive tool and comes in several kinds: digital, analog, and brain-like. An analog telephone connects two telephones with a wire. Talking causes a current to flow on the wire. In a digital telephone the voltage is converted into groups of ones or zeros and sent at high speed from one telephone to the other. An analog telephone requires one simple step. A digital telephone requires several million discrete steps per second. Digital telephones work because the hardware has gotten much faster. Yet brains constructed of slow devices and using a few watts of power are competitive for many cognitive tasks. The important question is not why machines are becoming so smart but why humans are still so good. Artificial intelligence is missing something important probably based on hardware differences.

scholarly journals Vibration and Long-Term Performance Analysis of Pile-Plank-Supported Low Subgrade of Ballastless Track under Excitation Loads

2015 ◽  
Vol 2015 ◽  
pp. 1-12 ◽  
Author(s):  
Junjie Huang ◽  
Qian Su ◽  
Ting Liu ◽  
Xun Wang
Keyword(s):  
High Speed ◽  
Experimental Results ◽  
Soft Ground ◽  
Board Structure ◽  
High Speed Railway ◽  
Ballastless Track ◽  
Long Term Performance ◽  
Term Performance ◽  
Frequency Sweeping

Pile-plank structures are widely applied for high-speed railway built in soft ground in China. It can be used as a reinforcement to improve the behavior of subgrade by providing vertical confinement to increase their stiffness and strength and reduce the subgrade settlement of ballastless track. However, the use of pile-board structure for soft ground reinforcement of high-speed railway is hindered by the existing gap between applications and theories. To verify vibration characteristics and long-term performance of pile-plank-supported low subgrade of ballastless track and the benefit of pile-board structure, an experimental study was conducted on low subgrade of pile-board under excitation loads using both in situ frequency sweeping and cyclic loading experiments. The frequency sweeping experimental results show that the pile-plank-supported low subgrade has smooth stiffness along the longitudinal subgrade and can effectively control the progressive effects of train speed on dynamic stiffness of the subgrade, which ensures driving safety and comfort. The cycle loading experimental results show that the pile-plank-supported low subgrade has favorable long-term dynamic stability, and its dynamic response is uniform along the longitudinal subgrade.

Asphalt in trackbed design

2020 ◽  
Author(s):  
Chrysoula Voulgari
Keyword(s):  
Parametric Analysis ◽  
High Speed ◽  
Base Layer ◽  
The Past ◽  
Traffic Loads ◽  
The World ◽  
High Speed Trains ◽  
Induced Stresses ◽  
Resistant Layer ◽  
Potential Use

<p>Conventional all granular trackbed has been in use around the world for many years, presenting good results although requiring a certain level of ongoing maintenance. Increasing traffic loads and volumes and particularly the introduction of high-speed trains in the last few decades, have resulted in the need for new approaches. To reduce train load-induced stresses in the track subgrade, one approach that has been introduced is the use of a Hot Mix Asphalt (HMA) layer as a partial or full replacement of the granular sub-ballast.</p><p>During the past few decades the use of HMA as a sub-ballast layer within the track structure has steadily increased until it has become standard practice in many countries around the world (USA, Japan, Germany, Italy etc.). The HMA mix is designed similarly to the base layer of highway pavements. Specifically, it is designed to be a medium modulus, flexible, low voids, fatigue resistant layer that will accommodate high tensile strains without cracking .</p><p>This paper provides a review of the potential use of an asphalt layer to replace the granular sub-ballast during the railway trackbed design.  A literature review of the use of asphalt in trackbed construction and a parametric analysis have been carried out to compare traditional ‘all granular’ and more recent asphalt layer solutions for different subgrade stiffnesses. </p><p>Results indicate various advantages of the use of asphalt in the trackbed; improving trackbed performance and decreasing the overall cost and environmental impact.</p>

Experimental Evaluation of Hydrodynamic Bearings for a High Speed Turbocharger

2014 ◽  
Vol 136 (7) ◽  
Author(s):  
Robley G. Kirk
Keyword(s):  
Limit Cycle ◽  
Experimental Evaluation ◽  
High Speed ◽  
Experimental Results ◽  
Fluid Film ◽  
Pressure Pulsations ◽  
The Past ◽  
Film Instability ◽  
Tilting Pad ◽  
Engine Testing

Many high speed turbochargers are known to operate with limit cycle vibration as a result of fluid-film instability. The goal of this research was to achieve a stable synchronous response with a minimum of self-excited nonsynchronous contribution. Those vibration components excited by the engine harmonics and exhaust pressure pulsations were not the target of this research. This paper will review the experimental results of the fixed geometry fluid-film bearing designs selected to replace the standard stock floating-ring design. In addition, the paper documents a novel radial tilting pad bearing concept that was designed to replace the fixed geometry bearings, with a minimum of modification to the stock bearing housing. A summary of the on-engine testing over the past seven years is documented in this paper.

An Investigation into Permissions Requested by Mobile Banking on Android Platform

2018 ◽  
Vol 9 (2) ◽  
pp. 12-30
Author(s):  
Latifa Er-Rajy ◽  
M. Ahmed El Kiram
Keyword(s):  
Mobile Technology ◽  
High Speed ◽  
Mobile Apps ◽  
World Population ◽  
Mobile Banking ◽  
The Past ◽  
Man In The Middle ◽  
The World ◽  
User Data ◽  
Mobile Banking Applications

In the past, banking took place only inside bank rooms, which was a task for customers and bankers at the same time. But in our day, thanks to the high-speed development and growth of mobile technology, the mobile phone platform had the power to create great opportunities for customers of the physical bank due to its capabilities and coverage of the population; this can be proved by the number of mobile subscriptions that approximates the world population figures. In order to explore these opportunities, most banks have already launched their mobile apps or have redesigned the mobile version of their websites. Among the advantages of using mobile banking is that users have the ability to make banking transactions, online payments or transfers, anywhere and at any time. In this article, we investigated the danger of the permissions requested by mobile banking applications, their effects on sensitive user data and their relationship with the attack called “Man in the middle” and its different forms. We took Morocco as a case of study.

Materials for High Speed Circuit Boards

1987 ◽  
Vol 108 ◽  
Author(s):  
R. W. Seibold ◽  
R. T. Lamoureux ◽  
S. H. Goodman
Keyword(s):  
High Speed ◽  
Circuit Boards ◽  
The Past ◽  
Defense Systems ◽  
Hazardous Environments ◽  
Data Rates ◽  
The World

During the past five years, the computer you bought with 128 Kbytes of memory has been upgraded by the availability of 40 Mbyte storage and modems which allow instant access to databases around the world. The continuing need to perform more complex missions for modern defense systems in more hazardous environments will call for substantially higher data rates than are available today.

More than representation

2018 ◽  
Vol 31 (3) ◽  
pp. 83-104 ◽  
Author(s):  
Oliver J. T. Harris
Keyword(s):  
Critical Issue ◽  
Paradigm Shifts ◽  
Assemblage Theory ◽  
Significant Challenge ◽  
The Past ◽  
The Enlightenment ◽  
The World ◽  
History Of

In this article I examine how Deleuzian-inspired assemblage theory allows us to offer a new challenge to the enlightenment categories of thought that have dominated archaeological thinking. The history of archaeological thought, whilst superficially a series of paradigm shifts, can be retold as arguments constructed within distinctions between ideas and materials, present and past, and culture and nature. At the heart of all of these has been the critical issue of representation, of how the gap between people and the world can be bridged. In the last decade or so, however, archaeologists have begun to make a more significant challenge to these ideas, and have attempted to offer a critique of our enlightenment heritage that is ontologically, rather than epistemologically, inspired. Drawing on the manner in which assemblages allow for the vibrancy of matter, are non-anthropocentric, multiscalar and more-than-representational, this article argues that Deleuzian thought offers the best chance to rework our understanding of the past in this manner. This is explored through a case study of three scales of analysis of Neolithic Britain.

Experimental Evaluation of Hydrodynamic Bearings for a High Speed Turbocharger

2013 ◽  
Author(s):  
Robley G. Kirk
Keyword(s):  
Limit Cycle ◽  
Experimental Evaluation ◽  
High Speed ◽  
Experimental Results ◽  
Fluid Film ◽  
Pressure Pulsations ◽  
The Past ◽  
Film Instability ◽  
Tilting Pad ◽  
Engine Testing

Many high speed turbochargers are known to operate with limit cycle vibration as a result of fluid-film instability. The goal of this research was to achieve a stable synchronous response with a minimum of self-excited non-synchronous contribution. Those vibration components excited by the engine harmonics and exhaust pressure pulsations were not the target of this research. This paper will review the experimental results of the fixed geometry fluid-film bearing designs selected to replace the standard stock floating-ring design. In addition, the paper documents a novel radial tilting pad bearing concept that was designed to replace the fixed geometry bearings, with a minimum of modification to the stock bearing housing. A summary of the on-engine testing over the past seven years is documented in this paper.

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