Top 5 challenges faced by Immigrants

Power of Immigrants

No matter whether you are planning for immigration or you are already an immigrant, it’s essential to gather as much information as you can, to understand the potential challenges you may face. Acknowledging there would be barriers in your way, is the first step in being a successful immigrants. In this article, we will look at some of those challenges and later, in a series of articles we will look at some of the solutions to tackle them.

  1. Language Problem

It is no surprise that the greatest barrier to integration into the host country is low language proficiency. Your ability in expressing your thoughts and needs, affects every aspects of your life. Language is a key communication indicator, which has a big impact on how others assess your general proficiency. Without a sufficient knowledge of official language in your host country, all your technical skills, qualifications and, experiences could be…

View original post 324 more words

How to simulate extinction cross section using the optical theorem?

I was asked to explain the method I used to simulate and find extinction cross section of the antennas in my paper. I thought I write a blog post for someone who might be looking for the same problem on the internet.

Well, there are basically two different methods. One method is to find the scattered fields by the scatterer. Then, one should calculate the power of scattered fields over the 4\pi steradian of the space. The power dissipated in the object should be also calculated. Then, one can find the extinction cross section by converting the sum of the absorbed and scattered powers into the cross section.

The second method, which is also simpler, is to use the optical theorem (see Wiki for further details). It readily relates extinction cross section with scattering amplitude of the object in the forward direction.

\sigma_{ext} = -\frac{4\pi}{k}  \Im{f(\hat{i},\hat{i})}

Therefore, we are down to finding scattering amplitude of the object. The method that I found simple to implement was introduced by Gustafsson et al (2012). This was introduced for the measurement purposes. I also used it to model the extinction cross section in full-wave EM packages like FEKO, CST, Ansys, etc. Based on this method, we place the scatterer in the origin. A spherical source is used to illuminate the scatterer, and the field is also recorded in the forward direction (AUT). We also measure(or simulate) without the presence of the scatterer. This is basically to get an account of the path loss and phase delay between the source and observation points.  Then, we can have:

Then, by the optical theorem, we can find the extinction cross section as:

\sigma_{ext}=\Im \{h\}


h=\frac{2\pi d}{k}( \frac{AUT-REF}{REF})^*.

Note 1: Time dependence

In the above discussions, a time dependence of \exp(j\omega t) is assumed. If one prefers $latex \exp(-j\omega t) dependence, he/she should change the sign in (1) and omit the conjugate operator in (2). I found this worth to mention since I was used to get negative cross sections while I measured my antennas in [1]. I spent almost two months, to measure, and re-measure, and re-measure the cross sections, and I was getting the negative cross sections. I started asking people about the issue. Finally, one of the authors in [2] pointed the time dpendence issue to me,

Note 2: On the modelling \sigma_{ext} of an antenna

Extinction cross section of an antenna can be found the same way as a general object. The only difference is one should add a load into the antenna terminals to setup the model or apparatus properly.

Note 3: 

The imaginary part of h stands for the extinction cross section, while I am not aware of any physical interpretation for the \Re h, though both of them have dimensions of the area. I believe intuitively one might somehow relate \Re h to the stored energy around the scatterer.

[1] M. Shahpari and D. V. Thiel, “The Impact of Reduced Conductivity on the Performance of Wire Antennas,” in IEEE Transactions on Antennas and Propagation, vol. 63, no. 11, pp. 4686-4692, Nov. 2015. doi: 10.1109/TAP.2015.2479241 arXiv: 1509.06709  RG: Priprint

[2] M. Gustafsson, J. B. Andersen, G. Kristensson and G. F. Pedersen, “Forward Scattering of Loaded and Unloaded Antennas,” in IEEE Transactions on Antennas and Propagation, vol. 60, no. 12, pp. 5663-5668, Dec. 2012. doi: 10.1109/TAP.2012.2214191 RG: Preprint



Matlab with Dual license keis

Those professionals who provide consultancy to different companies often need to use the license keies provided by the particular firm. This often involves using VPN connection to the server and also change of the license kies. Fortunately, change of the licenses are possible in Matlab. In this method illustrated in Matlab Central, we introduce a second license server, in case the connection to the first server is down, Matlab looks up the second license server. Having said that, the first server should be the most commonly used server since Matlab tries to ping it first and waits for its response. Running the Matlab with the second license is considerably slower.

The first method to make a dual license configuration work is by environment variables

To enable this configuration, follow the instructions below:

Create an environment variable, MLM_LICENSE_FILE, and set it to the port@host of the server machines in order. For example:



The second method is to edit the shortcut to the Matlab icon by:

C:\…\matlab.exe -c port@hostname1;port@hostname2

However, I don’t personally use the second method since it looks I have to edit all the shortcuts (Start Menu, Desktop, etc) to run Matlab.

Finaly, Matlab support team provides the following extra tips:

NOTE: If you are running an R13 client or below, you will not be able to run the license manager in the port range 27000-27009. To allow this failover, you will need to set the port number for the license manager to a range such as 1700-1711.

Also, a colon should be used rather than a semicolon on Non-Windows (Unix) systems.

For MATLAB Distributed Computing Server, worker licenses can be split up between two license server systems since each worker license is a seperate MDCS session.


Beginners guide to writing a manuscript in LaTeX —

Interactive course available now. LaTeX is a document preparation system for the communication and publication of scientific documents that include complex math expressions or non-Latin scripts, such as Arabic, Sanskrit and Chinese. It is widely used in many fields in academia, including mathematics, physics, computer science, statistics, economics and political science. In LaTeX the writer […]

via Beginners guide to writing a manuscript in LaTeX —

Do It Yourself (& not just on Tuesdays!)

Shut Up & Write Tuesdays

Here at Shut Up & Write Tuesdays we love it when the folks who make up our little community take an idea and run with it. At the moment we’re particularly enamoured with #diysuwt, the hashtag that folks are using to organise their own shut up & write sessions on Twitter.

If you like the Shut Up & Write Tuesdays model, but can’t make it to our sessions or prefer to write on other days, then #diysuwt is for you! Our lovely @SUWTUK host Louca-Mai Brady has put together the following tips, to help you get the hang of it…

  • Use the hashtag to notify others that you are going to be writing, to see if they want to join you, and to let them know when you are starting, finishing, and taking a break
  • Use the Pomodoro format to write in blocks of 25minutes, with a 5minute break between…

View original post 92 more words

Grants for electromagnetic research

I am writing this post thrilled with the fantastic news on the outcome of the first round of ARC grant announcements in 2016. On Friday 6th May, ARC announced the winners of ARC Laurette fellowships, ARC linkage projects, and ARC research hubs for collaboration with industry.

It is warm heartening that researchers from the University of Queensland and University of Adelaide could secure funding to do research on antennas, microwaves, and EM related projects.

Prof. Abbosh from ITEE of UQ is a leader on two industrial projects for collaboration with EM solutions and LICENSYS companies. The project with EM solutions is about providing satellite communications to those who live in rural and remote areas. This project is similar to one of the ARC discovery projects in our centre GBDTC which is led by Prof. Guo. Both grants promise to find innovative practical solutions to provide broadband internet to the remote areas.

Reconfigurable antennas for satellite on-the-move communications.

This project aims to design and develop low-cost reconfigurable end-user antennas that could be integrated with low-earth-orbit satellites so regional and remote Australians can access broadband. While broadband is taking its place alongside water and electricity as essential infrastructure, people in regional Australia lack genuine broadband services. These antennas are expected to give these communities reliable access to e-health services and distance education, and make their businesses more productive with access to new markets. The proposed antennas should also make broadband services available in the air, at sea, or on the move.

Another project is about collaboration with LICENSYS company and also QLD department of transport and main roads. It is anticipated that this project can provide real time information gathering about the roads and assist in making efficient decisions on the road and traffic management. Use of the radar technology in the heart of the project is something that I love 🙂 😉

In-road microwave system for traffic monitoring and vehicle identification.

This project aims to develop a cost-effective, in-road microwave radar system for traffic monitoring and vehicle identification. The ever increasing number of vehicles on our roads makes conventional approaches to traffic management less effective and prohibitively expensive. The new system will integrate chip-enabled license plate technology with novel microwave radar techniques to produce real-time data that supports immediate intervention for improved road safety, vehicle identification and driver validation. Multiple sensors will also provide uniquely rich data to improve traffic management decisions, road infrastructure planning and operation. This research could significantly reduce the effect of traffic incidents and congestions across Australia.

Prof. Fumeaux of Unversity of Adedaide is a founding member of a research hub for graphene research. Below is a summary of the mission statement of the research hub:

ARC Research Hub for Graphene Enabled Industry Transformation.

This research hub aims to provide the advanced materials industry with innovative solutions to tackle critical and complex challenges of national significance. The hub intends to leverage substantial existing and new investments to overcome fundamental scientific barriers and develop fit-for-purpose graphene products with and for its partners. Advanced materials, particularly graphene, are now considered promising for maintaining competitive advantages for industrial transformational progress; and advanced industries to drive prosperity where innovation underpins business to thrive globally. The anticipated impacts are long-term economic prosperity and growth.

I would like to warmly congratulate them and wish them all the best for their research.

P.S. Grant summaries are copied from the ARC RMS public website.

Electromagnetic section in arXiv

I stumbled upon a survey from arXiv admin team, few days ago when I loaded the arXiv front page. The survey was about the current and future needs of the arXiv library. Well,  I took the opportunity to share few comments about arXiv that I had in mind over the years. It took me around 10-15 minutes to complete the survey,  and I would recommend my peers to do so.

One of the first questions was which topics and categories should be added to arXiv? As a researcher involved and enthusiastic about the electromagnetic theory and its applications, I really feel that papers related to antennas, microwave, propagation of waves, and electromagnetic theory should be classified together. The current situation is really frustrating that we do not get enough support for such categories in arXiv. It is hard to keep track of preprints about our fields that are posted on arXiv. One reason is that each paper goes to a different category, that is not best suited to its contents. Therefore, not much attention is received for these preprints as they are not classified correctly. There are numerous examples of such preprints. For instance:

There are numerous examples of such preprints. For instance: a bunch of preprints from the researchers from Lund and KTH universities are classified as “classical physics” or “mathematical physics.” I agree that these papers are closely related to the above subjects, but they are more relevant to antennas and electromagnetics.

  • Gustafsson, Mats, and B. Lars G. Jonsson. “Stored electromagnetic energy and antenna Q.” arXiv preprint arXiv:1211.5521 (2012).
  • Nordebo, Sven, et al. “On the natural modes of helical structures.” arXiv preprint arXiv:1502.00496 (2015).
  • Jonsson, B. Lars G., and Mats Gustafsson. “Stored energies in electric and magnetic current densities for small antennas.” Proceedings of the Royal Society of London A: Mathematical, Physical and Engineering Sciences. Vol. 471. No. 2176. The Royal Society, 2015. arXiv:1410.8704 [physics.class-ph]
  • Jonsson, B. Lars G., Christos I. Kolitsidas, and Nasir Hussain. “Array antenna limitations.” Antennas and Wireless Propagation Letters, IEEE 12 (2013): 1539-1542. arXiv:1307.2925 [physics.class-ph]

Another example is from the works of my great friend Miloslav Čapek from Czech Technical University where his works are classified as computational physics, optics, and classical physics.

  • Jelinek, L., and M. Capek. “Optimal Currents on Arbitrarily Shaped Surfaces.” arXiv preprint arXiv:1602.05520 (2016).
  • Capek, Miloslav, and Lukas Jelinek. “Optimal Composition of Modal Currents For Minimal Quality Factor Q.” arXiv preprint arXiv:1602.04808(2016).
  • Capek, Miloslav, Pavel Hazdra, and Michal Masek. “On Some Theoretical and Numerical Aspects of Characteristic Mode Decomposition.” arXiv preprint arXiv:1509.02825 (2015).

My personal experience with arXiv submissions is that authors often do not get too much choice on which categories should be used for their preprints. Most of the time, arXiv administrators decide and override authors’ suggestions for the classification of preprints.


What can we do?

As individual researchers, we can participate in the survey and raise this need to arXiv admins. However, it might be more influential to write a succinct email to the arXiv admin and ask for the electromagnetic category in arXiv. Below is a link to the survey:

Another push might be to act as the community of scholars under the umbrella of IEEE AP-S, IEEE MTT-S, and IEEE EMC-S societies. Few years ago, IEEE Inf. Theory asked for such categories relevant to their field. That is why we see sub topics like Information Retrieval; Information Theory and Information Networks on arXiv.

I strongly believe that such category would be beneficial to all those active and interested in the EM theory and its applications. I hope EM community also support this idea!