Alex Clay Cushley

Alex Clay Cushley
Royal Military College of Canada · Department of Physics and Space Science

BSc, BEd, MSc, PhD, RMC, OCT

About

84
Publications
13,947
Reads
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75
Citations
Introduction
I am a veteran of the Canadian Forces and recently completed my PhD in physics at the Royal military College of Canada. My main research involves using signals of opportunity for ionospheric sounding, to reconstruct maps of the ionospheric electron content. Other activities include setting up them satellite communications ground station at RMC, and development of space-based Automatic Dependent Surveillance Broadcast for the dual purpose of air traffic management and ionospheric sounding.
Education
September 2010 - May 2013
September 2009 - May 2010
Queen's University
Field of study
  • Education (Intermediate/Senior Physics and Mathematics)
September 2004 - May 2009
Royal Military College of Canada
Field of study
  • Space Science

Publications

Publications (84)
Article
Full-text available
Numerical modeling has demonstrated that Automatic Identification System (AIS) signals can be used not only to estimate vertical total electron content (TEC) to supplement current TEC maps and data assimilation models but also to reconstruct two-dimensional (2-D) electron density maps of the ionosphere using computerized tomography. A ray tracing m...
Presentation
Full-text available
Using the Faraday rotation of AIS signals from ships for ionospheric sounding; vertical total electron content (VTEC) and 2d electron density mapping using ray tracing and computerized ionospheric tomography (CIT). Paper in preparation.
Poster
Full-text available
Numerical modelling has demonstrated that signals of opportunity, such as Automatic Dependent Surveillance Broadcast (ADS-B), Automatic Identification System (AIS) and amateur radio signals are subject to Faraday rotation (FR) as they pass through the ionosphere and may be useful for ionospheric sounding in addition to their intended operational pu...
Article
A plane polarized electromagnetic (EM) wave that propagates through a plasma, (anti-)parallel to a magnetic field, experiences a gradual rotation of its plane of polarization called Faraday rotation (FR). The FR angle depends on the integrated product of the electron density and the strength of the parallel magnetic field projection to the radio wa...
Poster
Full-text available
A plane polarized electromagnetic (EM) wave that propagates through a plasma, (anti-)parallel to a magnetic field, experiences a gradual rotation of its plane of polarization called Faraday rotation (FR). The FR angle depends on the integrated product of the electron density and the strength of the parallel magnetic field projection to the radio wa...
Poster
Full-text available
Radio waves propagating through plasma in the Earth’s ambient magnetic field experience Faraday rotation; the plane of the electric field of a linearly polarized wave changes as a function of the distance travelled through a plasma. Linearly polarized radio waves at 1090 MHz frequency are emitted by Automatic Dependent Surveillance Broadcast (ADS-B...
Poster
Full-text available
A plane polarized electromagnetic (EM) wave that propagates through a plasma, (anti-)parallel to a magnetic field, experiences a gradual rotation of its plane of polarization called Faraday rotation (FR). The FR angle depends on the integrated product of the electron density and the strength of the parallel magnetic field projection to the radio wa...
Poster
Full-text available
Radio waves propagating through plasma in the Earth’s ambient magnetic field experience Faraday rotation (FR); the plane of the electric field of a linearly polarized wave changes as a function of the distance travelled through a plasma. Linearly polarized radio waves at 1090 Mhz frequency are emitted by Automatic Dependent Surveillance Broadcast (...
Article
Radio waves propagating through plasma in the Earth's ambient magnetic field experience Faraday rotation; the plane of the electric field of a linearly polarized wave changes as a function of the distance travelled through a plasma. Linearly polarized radio waves at 1090 MHz frequency are emitted by Automatic Dependent Surveillance Broadcast (ADS-B...
Presentation
Full-text available
A plane polarized electromagnetic (EM) wave that propagates through a plasma, (anti-)parallel to a magnetic field, suffers a gradual rotation of its plane of polarization called Faraday rotation (FR). Likewise, radio beacon signals that traverse the ionospheric plasma encounter a (anti-)parallel component of Earths geomagnetic field and the anisotr...
Poster
Full-text available
Automatic Dependent Surveillance Broadcast (ADS-B) is a technology developed to track the position and movement of aircraft through intermittent broadcasts of their identity, itinerary and position state vectors to ground based receivers and other aircraft within range. The system is intended to replace radar as the standard for air traffic control...
Presentation
Full-text available
Radio waves propagating through plasma in the Earth’s ambient magnetic field experience Faraday rotation; the plane of a linearly polarized wave changes as a function of the distance travelled through a plasma. Linearly polarized radio waves at 1090 MHz frequency are emitted by ADS-B devices which are installed on most commercial aircraft. These ra...
Poster
Full-text available
A plane polarized electromagnetic (EM) wave that propagates through a plasma, (anti-)parallel to a magnetic field, suffers a gradual rotation of its plane of polarization called Faraday rotation (FR). Likewise, radio beacon signals that traverse the ionospheric plasma encounter a (anti-)parallel component of Earths geomagnetic field and the anisotr...
Presentation
Full-text available
A plane polarized wave that propagates through a plasma, parallel to a magnetic field, suffers a gradual rotation of its plane of polarization called Faraday rotation (FR). Likewise, radio beacon signals that traverse the ionospheric plasma encounter a parallel component of Earths geomagnetic field and the anisotropy of the medium. Many authors use...
Presentation
Full-text available
The Global Navigation Satellite System constellations have been used to collect sufficient total electron content (TEC) measurements over unique propagation paths using ground-based receivers to produce global ionospheric maps and to satisfy the ill-posed problem of tomographic reconstruction of the ionospheric electron content. The approach is con...
Poster
Full-text available
F Previous work has shown that FR measurements can be used to obtain the TEC along the paths [6, 18]. The program was used to generate TEC outputs from rays that passed from given locations, at an initial elevation angle through the input electron density profile to a given satellite location [18]. The TEC and raypath geometry are used to reconstru...
Conference Paper
Full-text available
Amateur radio and other transmissions used for dedicated purposes, such as the Automatic Packet Reporting System (APRS) and Automatic Dependent Surveillance Broadcast (ADS-B), are signals that exist for another reason, but can be used for ionospheric sounding. Whether mandated and government funded or voluntarily constructed and operated, the...
Presentation
Full-text available
Amateur radio and other signals used for dedicated purposes, such as the Automatic Position Reporting System (APRS) and Automatic Dependent Surveillance Broadcast (ADS-B), are signals that exist for another reason, but can be used for ionospheric sounding. Whether mandated and government funded or voluntarily constructed and operated, these network...
Conference Paper
Full-text available
The proposed launch of CanX-7, carrying a space-borne ADS-B receiver developed by the Royal Military College of Canada will create a unique opportunity to study the modification of the 1090 MHz radio waves following propagation through the ionosphere from the transmitting aircraft to the passive satellite receiver. Our previous work has successfull...
Article
Full-text available
Key Points: • The modeled ionospheric electron densities were reconstructed using CIT • Mesoscale ionospheric features can be detected without a priori knowledge Abstract Numerical modeling has demonstrated that Automatic Dependent Surveillance Broadcast (ADS-B) signals can be used to reconstruct two-dimensional (2-D) electron density maps of the i...
Conference Paper
Full-text available
tool to prioritize other instrument campaigns (eg, Incoherent Scatter Radar). The final reconstruction used a quiet profile a priori guess to refine the altitude distribution of the features. Input electron density profile to ray-trace. Reconstruction without a priori guess. Reconstruction with quiet a priori guess. Conclusion • CIT with ADS-B data...
Conference Paper
Full-text available
Numerical modelling has demonstrated that ADS-B signals can be used to reconstruct two dimensional (2D) electron density maps of the ionosphere using techniques for computerized tomography (CT). Ray-tracing techniques were used to determine the characteristics of individual waves, including the wave path and the state of polarization at the satelli...
Thesis
Full-text available
The proposed launch of a CubeSat carrying the first space-borne ADS-B receiver by RMCC will create a unique opportunity to study the modification of radio waves following propagation through the ionosphere as the signals propagate from the transmitting aircraft to the passive satellite receiver(s). Experimental work is described which successfully...
Presentation
Full-text available
Computerized Ionospheric Tomography: Reconstruction of Ionosphere Electron Density Profiles Using Modelled TEC Measurements From ADS-B Model.
Conference Paper
Full-text available
The Royal Military College of Canada (RMCC) plans to demonstrate a technology that has the potential to vastly improve the management of air traffic and reduce green house emissions produced by inefficient flight routes. RMCC proposes a microsatellite mission, SABRE, which will be equipped with an Automatic Dependent Surveillance - Broadcast (ADS-B...
Conference Paper
Full-text available
As part of its research program in space mission analysis & design, and proposed CubeSat operations, the Royal Military College of Canada (RMCC) Center for Space Research (CSR) has developed an amateur satellite communication ground station. The ground station has been implemented to support staff and student research, teaching and learning opportu...
Article
Full-text available
Automatic Dependent Surveillance - Broadcast (ADS-B) is a system in which aircraft continually transmit their identity and GPS-derived navigational information. ADS-B networks for air traffic monitoring have already been implemented in areas around the world, but ground stations cannot be installed in mid-ocean and are difficult to maintain in the...

Questions

Questions (36)
Question
The AGM-114 Hellfire missile has a tail control surfaces. Tail control is best for high angle-of- attack (AOA) and for air-to-air whereas the AGM-114 is an air-to-ground missile mostly launched at ground targets from an effective range of 8-11 miles (depends on variant). Does anyone know how this discrepancy can be explained?
Question
When a shaped charge detonates there is a jet component and a slug. It is my understanding that the jet is a high temperature, high pressure flow of molten metal that erodes the targets armor, whereas the slug is like a cork or plug to direct the flow into the target rather for maximum penetration. A colleague told some of the students that it is a misconception that the jet is molten metal and that it is really solid metal because it doesn't have time to change phase and acts like a super fluid. Is the jet resulting from a shaped charge molten metal or solid?
Question
I have found different characteristic values given for the standoff distance to achieve optimal jet formation and therefore penetration using a shaped charge. Walter and Zukas give 2-4 cone diameters. Another plot I saw peaked at 60 cm for a 10 cm CD and the acceptable range was 2-6 CD. Is there an equation to determine the optimum theoretical standoff distance for a shaped charge? I suspect such an equation would take into account the cone liner material, density, mass ratio to explosive material to liner, liner thickness, etc. What is the optimum standoff distance for a shaped charge to achieve maximum penetration?
Question
For a radial charge geometry in a solid rocket, is there an equation or rule of thumb to determine the minimum hole size in the solid propellant charge? I suspect the answer is "no" since an infinitesimally small hold diameter would result in an axial burn geometry, OR that it is relates to the Web Fraction: bf = b / r, where Web Thickness (b) is the minimum thickness of the grain to burning surface or casing, and r is the grain radius.
Question
NASA's unmanned X-34 shcramjet demonstration sub-orbital aircraft is air-launched from Orbital Sciences Corp.’s L-1011, a commercial jetliner originally modified to carry the company’s expendable Pegasus launch vehicle. I understand that shcramjet engines need to be boosted to supersonic velocity before they start to work, but I am wondering, "why they are air-launched rather than boosted using a rocket from the ground?"
I suspect it has something to do with reducing vibrations and g-forces on instruments and sensors, or concurrently demonstrating reusable launch vehicle technology, other than the Pegasus, which is considered expendable. I am wondering about the cost difference as well.
Question
I am teaching a course and came across applications of inductors in remote detonating systems, detonators and fuzes like the FMU-143 penatrating bomb fuze system, but I have not found much information on how excatly they are used.
I assume they are used as isolation transformers for safety reasons but would like to know more. For example, " The flux compression generator is one alternative to capacitors. When fired, it creates a strong electromagnetic pulse, which is inductively coupled into one or more secondary coils connected to the bridge wires or slapper foils. "
I think this would be an interesting example for my students (especially since I am at a military College). Any information and references would be appreciated.
Thank you in advance for your contributions.
Question
I was reading this article from 1974 and wondered whether others felt like the list of considerations that led to the most appropriate journal to publish in has changed drastically.
Herbert Inhaber, Is there a pecking order in physics journals? Physics Today 27, 5, 39 (1974); https://doi.org/10.1063/1.3128587.
" There is the matter of audience; of the probable delay between acceptance and publication; of article format (letter, review, standard research report). If the article is potentially controversial, the author may estimate its chances of being accepted by different journals. Considerations of national pride may sway the choice: An author may submit a work to a journal in his own country rather than to one that has a greater circulation and impact but is published in a foreign country. "
Personally, I usually gravitate to submitting to the same journal that most of my references are from since that would likely be the most relevant audience. I have never published in a Canadian journal, but have reviewed articale submitted to the Canadian Journal of Physics and noticed many authors from countries that lack reputable journals will submit manuscripts to North American and European journals, particularly those with little or no publication fees. I don't think time between submission to publication is relevant at all with the internet, online publishing or pre-prints and self-publishing sites like arxiv.org.
I am very interested what others think. In particular, what do you think is the most important consideration today: impact factor, open access, immediacy, publication cost, or something else?
Thank you in advance for your contributions to this discussion!
Question
What is the highest critical frequency f0F2 ever recorded? Is anyone aware of a paper/reference or published ionogram for the reflection of 50 MHz (or higher) radio waves by the Ionosphere at incidence?
"At incidence, generally frequencies below 10 MHz are reflected but with active events frequencies up to 50 MHz and higher may also be reflected by the E-layer."
Thank you for your contributions in advance!
Best regards,
Alex
Question
I just read the following article from Physics Today called Commentary: On the quality and costs of science publication:
I think this article echos some of the concerns for scientific publication, particularly the trad-offs between cost and quality. I started another discussion about 2 months ago looking for a journal in my field with a reasonably high impact factor, but low (or no) publication costs because the availability of funds for this coming year are uncertain..
If I don't have the funds for high quality pay-to-publish journals like AGU, is it better to use a preprint server like arXiv.org (or even Research Gate), or to publish in low impact free journals? Furthermore, should we as scientists be making a conscious and concerted effort to move away from pay-to-publish journals to improve the access to publishing and quality science?
Question
Hello,
I have a research paper in preparation but am uncertain whether I will have enough funds available to publish in the journal that I usually publish in (Radio Science). The topic is Ionospheric Tomography Using Signals of Opportunity.
What would be a reputable free alternative? I found Advances in Radio Science (ARS) but there is a limit on the length and my paper is currently about 10-16k words with 17-20 figures.
Best regards,
Alex
Question
Typical values of vertical total electron content (VTEC) seem to be about 1 to 100 TECu. I was wondering, what is the highest value of TEC (slant or vertical) that has ever been recorded? Please provide a reference. Thank you in advance for your contributions to this discussion.
Best regards,
Alex

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