Estimation of the penetration angle of a man-made tunnel using time of arrival measured by short-pulse cross-borehole radar

Geophysics ◽  
2010 ◽  
Vol 75 (3) ◽  
pp. J11-J18 ◽  
Author(s):  
Sang-Wook Kim ◽  
Se-Yun Kim ◽  
Sangwook Nam
Keyword(s):  
Arrival Time ◽  
Short Pulse ◽  
Test Site ◽  
Radar System ◽  
Time Of Arrival ◽  
Arrival Times ◽  
Borehole Radar ◽  
Deep Underground ◽  
Electromagnetic Signals ◽  
Amplitude Level

The relatively fast propagation of electromagnetic signals through empty man-made tunnels has played a key role in detecting deep underground tunnels using a short-pulse cross-borehole radar system. Our cross-borehole radar system measured the pulse signatures of an obliquely penetrating tunnel using eight different borehole pairs at a test site in Korea. Compared to the arrival times of the first peaks, the arrival times of the first received signals at an appropriate amplitude level provided an increasingly clear indication of the empty tunnel as its penetration angle became more oblique. A quadratic relationship between the arrival time of the first received signal and the oblique angle of the empty tunnel was obtained in pure granite.

scholarly journals Periodic Changes in Intensity and Arrival Time of Pulses from the Vela Pulsar: Evidence for Free Precession?

1996 ◽  
Vol 160 ◽  
pp. 101-102
Author(s):  
A.A. Deshpande ◽  
P.M. McCulloch
Keyword(s):  
Arrival Time ◽  
Time Of Arrival ◽  
Free Precession ◽  
Dual Frequency ◽  
Arrival Times ◽  
Routine Monitoring ◽  
Vela Pulsar ◽  
Observed Behaviour ◽  
Pulse Arrival ◽  
Periodic Changes

We present dual-frequency measurements on the Vela pulsar with a view to study the slow variations in the pulsed flux and the apparent differences in the pulse arrival times. We examine the data for correlated variations between the pulse intensities and arrival times at the two frequencies and discuss two main possibilities in order to explain the observed behaviour.The data presented here consists of a) Pulse intensities, S635& S950, at S635& S950MHz respectively and b) the ‘residual’ differences in the time of arrival of the pulse at the lower frequency, ΔTOA, with respect to that at the higher frequency. These data, over a span of ~1300 days (during 1988-92), were obtained as a part of the routine monitoring of the Vela pulsar from Mt. Pleasant Observatory of University of Tasmania, Hobart (see McCullochet al. 1990).

Borehole radar applied to characterization of fracture zones

1989 ◽  
Vol 20 (2) ◽  
pp. 149 ◽  
Author(s):  
O. Olsson ◽  
L. Falk ◽  
O. Forslund ◽  
B. Niva ◽  
E. Sandberg
Keyword(s):  
Granitic Rock ◽  
Short Pulse ◽  
3D Models ◽  
Radar System ◽  
Fracture Zones ◽  
Borehole Logging ◽  
Single Hole ◽  
Pulse Radar ◽  
Borehole Radar

A new short-pulse radar system (RAMAC) developed by ABEM AB has now been in operation for three years during which more than 100 km of borehole logging has been performed. The bulk of the surveys have been in granites and gneisses.The RAMAC system operates at centre frequencies in the interval 20 to 60 MHz. At those frequencies single-hole reflection ranges of 50 to 150 m are normally obtained in gneissic and granitic rock. Cross-hole ranges have in some cases exceeded 300 m. The large probing range in combination with resolution of the order of a few metres makes borehole radar a unique technique for investigation of fracture zones in crystalline rock.Case histories illustrate application of the RAMAC system in three different configurations (single-hole reflection, cross-hole reflection, and cross-hole tomography) and demonstrate how combination of these three can yield consistent 3D models of fracture zones and other structures.

Quantifying Optical Tip-Timing Probe Error With Laboratory Apparatus

2011 ◽  
Author(s):  
Bruce D. Hockaday
Keyword(s):  
Arrival Time ◽  
Optical Signal ◽  
Data Conversion ◽  
Time Of Arrival ◽  
Optical Probes ◽  
Engine Operation ◽  
Timing Resolution ◽  
Blade Tip ◽  
Dynamic Errors ◽  
Made In

Detection of airfoil time of arrival with optical probes has been evolving since the 1980s. Time of arrival data are used to infer airfoil stresses caused by vibration through a sequence of manipulations. The data conversion begins by converting arrival time to blade position, so blade deflection can be determined from the expected non-vibrating position. Various methods are used in the industry to convert deflection data to frequency, amplitude, and stress, which is beyond the scope of this paper. Regardless of the analytical approach used, producing accurate stress information relies on the precise detection and measurement of time of arrival, which equates to blade position. Recent improvements have been made in time of arrival system accuracy by running faster clocks to increase temporal resolution of the measurement. Greater timing resolution, afforded by clock speed, will have diminishing returns when probe and blade-tip interactions begin producing dominant errors. In the case of optical probes, the blade-tip needs to be treated as a curved reflector in the optical system that is capable of introducing dynamic errors. In engine operation the blade-tip moves axially under the probe from untwist, static deflection, and vibration, causing the light to reflect from different parts of the blade-tip. This relative movement between the probe and blade-tip cause the arrival time to change dynamically. Neglecting the dynamic arrival errors caused by the blade-tip’s optical properties will result in blade deflection-errors that propagate into the stress information. This paper presents a laboratory study that quantifies time of arrival errors due to optical interaction with tip radii. The study reports measured arrival position error as a function of location and optical signal power levels. The work is presented in terms of arrival position, producing information that is independent of rotational speed, and vibratory mode.

Distribution of arrival times in cosmic ray showers

1978 ◽  
Vol 10 (4) ◽  
pp. 730-735
Author(s):  
H. S. Green
Keyword(s):  
Cosmic Radiation ◽  
Three Dimensional ◽  
Stochastic Theory ◽  
Cosmic Ray ◽  
Time Of Arrival ◽  
Air Showers ◽  
Actual Distribution ◽  
Arrival Times ◽  
Primary Particles ◽  
Theoretical Analyses

The theoretical analyses of the extensive air showers developing from the cosmic radiation has its origins in the work of Carlson and Oppenheimer (1937) and Bhabha and Heitler (1937), at a time when it was thought that such showers were initiated by electrons. The realization that protons and other nuclei were the primary particles led to a reformulation of the theory by Heitler and Janossy (1949), Messel and Green (1952) and others, in which the production of energetic pions and the three-dimensional development of air showers were accounted for. But as the soft (electromagnetic) component of the cosmic radiation is the most prominent feature of air showers at sea level, there has been a sustained interest in the theory of this component. Most of the more recent work, such as that by Butcher and Messel (1960) and Thielheim and Zöllner (1972) has relied on computer simulation; but this method has disadvantages in terms of accuracy and presentation of results, especially where a simultaneous analysis of the development of air showers in terms of several physical variables is required. This is so for instance when the time of arrival is one of the variables. Moyal (1956) played an important part in the analytical formulation of a stochastic theory of cosmic ray showers, with time as an explicit variable, and it is essentially this approach which will be adopted in the following. The actual distribution of arrival times is cosmic ray showers, for which results are obtained, is of current experimental interest (McDonald, Clay and Prescott (1977)).

scholarly journals Detection of specific areas and densities for ultrasound tomography

2019 ◽  
pp. 121-127
Author(s):  
Victoria Erofeeva ◽  
Vasilisa Galyamina ◽  
Kseniya Gonta ◽  
Anna Leonova ◽  
Oleg Granichin ◽  
...  
Keyword(s):  
Image Reconstruction ◽  
Ultrasound Imaging ◽  
Arrival Time ◽  
Detection Accuracy ◽  
Problem Solution ◽  
Ultrasound Tomography ◽  
Arrival Times ◽  
Whole Process ◽  
Imaging Reconstruction ◽  
Tomography Data

In this paper we consider the problem of ultrasound tomography. Recently, an increased interest in ultrasound tomography has been caused by non-invasiveness of the method and increased detection accuracy (as compared to radiation tomography), and also ultrasound tomography does not put at risk human health. We study possibilities of detection of specific areas and determining their density using ultrasound tomography data. The process of image reconstruction based on ultrasound data is computationally complex and time consuming. It contains the following parts: calculation of the time-of-flight (TOF) of a signal, detection of specific areas, calculation of density of specific areas. The calculation of the arrival time of a signal is a very important part, because the errors in the calculation of quantities strongly influence the total problem solution. We offer ultrasound imaging reconstruction technology that can be easily parallelized. The whole process is described: from extracting the arrival times of signals raw data feeding from physical receivers to obtaining the desired results.

Mobile Enabled RFID-GPS Based Bus Tracking System

2014 ◽  
Vol 6 (4) ◽  
pp. 10-34 ◽  
Author(s):  
Suresh Sankaranarayanan ◽  
Paul Hamilton
Keyword(s):  
Public Transportation ◽  
Tracking System ◽  
Research Work ◽  
Transportation Systems ◽  
Urban Transport ◽  
Time Of Arrival ◽  
Rfid Technology ◽  
Arrival Times ◽  
Traffic Lights ◽  
Bus Stops

Public transportation in many countries is being used as a means of transport for travelling and accordingly people would prefer these public transportation to be scheduled properly, on time and the frequency be adequately fixed for commuters to make good use of it. It has been found that quite an amount of research work has been carried out, by way of using RFID technology in the public transportation systems towards the tracking of passengers when they board and exit buses. In addition research has also been carried out in using GPS towards the tracking of buses along with RFID technology at traffic lights, bus stops, intersections etc and also displaying expected arrival times on LCD screen at bus stops along with their current positions. Taking these aspects into consideration, an intelligent mobile bus tracking system for the Jamaican Urban Transport Corporation has been proposed and validated as a case study. The proposed system also enables commuters towards tracking the bus of their choice and also knowing their expected arrival times. So taking the above aspects into consideration, in this research the authors have proposed and validated on how control center of a bus company could track the location of a bus based on information received from RFID reader and GPS Transmitter positioned at various Bus stops and in the Bus and accordingly the expected time of arrival calculated for displaying the information on commuter's handset via Gmap. The implementation of the bus tracking scheme has been carried out using Adobe Flash player and Java.

scholarly journals Analysis of the Borehole Effect in Borehole Radar Detection

Sensors ◽  
2020 ◽  
Vol 20 (20) ◽  
pp. 5812
Author(s):  
Wentian Wang ◽  
Sixin Liu ◽  
Xuzhang Shen ◽  
Wenjun Zheng
Keyword(s):  
Relative Permittivity ◽  
Mutual Coupling ◽  
Propagation Speed ◽  
Wave Pattern ◽  
Radar System ◽  
Circular Array ◽  
Multiple Reflections ◽  
Borehole Radar ◽  
The One ◽  
Transmitting Antenna

The directional borehole radar can accurately locate and image the geological target around the borehole, which overcomes the shortcomings that the conventional borehole radar can only detect the depth of the target and the distance from the borehole. The directional borehole radar under consideration consists of a transmitting antenna and four receiving antennas equally distributed on the ring in the borehole. The nonuniformity caused by the borehole and sonde, as well as the mutual coupling among the four receiving antennas, will have a serious impact on the received signal and then cause interference to the azimuth recognition for the targets. In this paper, Finite difference time domain (FDTD), including the subgrid, is applied to study these effects and interferences, and the influence of borehole, sonde, and mutual coupling among the receiving antennas is found. The results show that, without considering the sonde and the fluid in the borehole, the one transmitting and one receiving borehole radar system does not have resonance, but the wave pattern of the reflected wave will have obvious distortion. For the four receiving antennas of the borehole radar system, there is obvious resonance, which is caused by the multiple reflections between the receiving antennas. However, when the fluid in the borehole is water and the relative permittivity of the sonde is low to a certain extent, the resonance disappears; that is, the generation of resonance requires a large relative permittivity material between the receiving antennas. When the influence of the sonde is considered, the resonance disappears because the relative permittivity of the sonde is low, which makes the propagation speed of the electromagnetic wave between the antennas accelerate and lose the conditions for resonance. In addition, the diameters of the sonde and the circular array of the receiving antennas can affect the received signal: the higher the diameter of the sonde and the higher the diameter of the circular array are, the better the differentiation of the received signal. The development of the research provides scientific guidance for the design and application of borehole radar in the future.

scholarly journals On optimal periodic dividend and capital injection strategies for spectrally negative Lévy models

2018 ◽  
Vol 55 (4) ◽  
pp. 1272-1286 ◽  
Author(s):  
Kei Noba ◽  
José-Luis Pérez ◽  
Kazutoshi Yamazaki ◽  
Kouji Yano
Keyword(s):  
Arrival Time ◽  
Arrival Times ◽  
Classical Sense ◽  
Capital Injection ◽  
Dividend Payments ◽  
Poisson Arrival ◽  
Optimal Dividend ◽  
Injection Strategies

Abstract De Finetti’s optimal dividend problem has recently been extended to the case when dividend payments can be made only at Poisson arrival times. In this paper we consider the version with bail-outs where the surplus must be nonnegative uniformly in time. For a general spectrally negative Lévy model, we show the optimality of a Parisian-classical reflection strategy that pays the excess above a given barrier at each Poisson arrival time and also reflects from below at 0 in the classical sense.

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