Energy Efficiency and Energy Intensity

Energy efficiency or efficient energy usage is a goal, aiming to reduce energy consumption by adopting new technology/means. For example, using LED bulbs instead of CFLs for lighting purpose reduces both energy consumption and the cost. Energy efficiency is an important means to handle growing energy demands or for sustainable energy.

Energy Intensity is a quantitative metric for nation’s energy efficiency.  For a country, it is calculated as the ratio of the total energy units consumed and the total units of GDP over a calendar year. The lower its value, the better is the energy efficiency. A higher value of energy intensity means more money is being spent on energy to convert it into nation’s GDP, which is bad.

Better Presentations – II

In this post, I will write about the TED talk by Mr. Richard Greene, author of the book, “The Words that Shook the World: 100 Years of Unforgettable Speeches and Events”.  In the talk, “The 7 secrets of the greatest speakers in history“, Richard first explains seven ingredients of a great talk, and then he shows video snippets of few great speakers including Loe Gehring, Winston Churchill, John F. Kennedy, Martin Luther King, among others. Here, I will re-phrase only the seven ingredients of his talk in five bullet points

  1. Words, Voice tone, and Body language: Richard’s experience/research shows that words, voice tone, and body language affect 7%, 38% and 55% of the audiences respectively. This means that uttering correct words/speech and neither having a variation (fast/slow according to condition) in voice tone nor using body language (looking, moving) will attract only 7% of the audience and the remaining will feel lost. Therefore to remain connected with the audience during the entire presentation, the presenter should ensure all three in appropriate proportions.
  2. Compelling Message: Ensure that your presentation has only one idea and try to plant the same idea in the audience.
  3. Only Conversation: Richard explains the difference between performance, presentation, and conversation. He further points out that a speaker often thinks his “talk” as a performance or a presentation. Thinking talk as “performance” is absurd because performance relates to acting and the talk is not acting, thinking talk as a “presentation” is not fully true because then you only think of the audience and not of yourself. Instead, talk is “conversation”. In the words of Richard, “Talk/public speaking is nothing but a conversation from your heart about something that you are authentically passionate about. “
  4. Four Languages of Communication: Presenter should ensure that his(r) presentation has following four languages. (i) Visual: Show visual representation of as many concepts as possible (ii) Auditory: Summarize findings through stories (iii) Auditory digital:  Support findings with analytical and statistical measures/numbers (iv) Kinesthetic: Develop means of connecting with audience, i.e., audience should feel the message/idea
  5. Authentic Passion: This is the most important one among all the previously mentioned. The presenter must ensure that the message is worth to present.

Better Presentations – I

A few days back I attended a doctoral symposium along with my fellow PhDs at NIIT Universiy, Neemrana, Rajasthan. It was a two-day event in which 17 Ph.D. students from elite educational institutions of India and few experts from Industry and Academia (IIT Profs.) gave presentations. Each presentation was around 15 – 20 minutes followed by 1-2 questions. After the symposium, I along with my colleagues discussed the presentations, i.e., which presentations were catchy and what were the reasons for boring presentations. I won’t repeat the discussion here, but I would like to say that the debate intrigued me to dig deep and understand the characteristics of better presentations.

In this post and another subsequent post, I will nail down the ingredients of a better presentation. In all these posts I will present views of world-class presenters. This post is based on a TED (Technology, Entertainment, and Design) talk by  Chris Anderson,  “TED’s secret to great public speaking“. Chris is the owner of the TED, a non-profit organization, organizing talks on ideas worth sharing. Chris mentions that there is no unique formula for giving a better presentation. It is not like that you tell catchy stories on red-velvet, rather presentation is means of transferring an idea from a presenter to an audience. He defines this idea transformation process as a synchronization problem, i.e., if the speaker’s and listeners’ minds get synched with one another then idea gets transferred quickly without losing the audience. To make sure that the synchronization will happen between the two parties while presenting, Chris mentions that a speaker should prepare his(r) talk while ensuring following ingredients in a talk:

  1. Develop presentation around one idea: Make sure that the presentation surrounds around one idea. All slides should support the idea.
  2. Develop curiosity in the audience: Provide motivation of the presentation, i.e., why is the presentation important and why should audience pay attention. Also, ask questions in between –  this will ensure uninterrupted bonding between the two participating parties.
  3. Develop each piece of presentation while keeping audience’s awareness in mind:  This means that the presentation should be at listener’s cognition level. Wait! how is it possible while delivering technical stuff to a non-domain audience? The only way to handle this issue is to use “metaphors” as often as possible. Using metaphors at audience level will require a little bit of creativity and time but it is worth to spend the time to get this skill.
  4. Ensure that the presentation adds value to the audience: If you find that the presentation will help audience then you should present, else it is better not to present.

Latex space reducing hacks

  1. Reduce space above and below equations: Place following lines after \begin{document}

2.  Reduce space above and below section/subsection titles. Place these lines before beginning the document.

*{\section} {0pt}{2\baselineskip}{3\baselineskip}
\titlespacing*{\subsection} {0pt}{2\baselineskip}{3\baselineskip}

This answer is copied from this StackOverflow link. In Springer, llncs format I found this sucks but a hack around the same is provided in this StackOverflow answer. It really works!!.

Side by side latex figure/table placement

1.  Place two figures side by side with separate captions and labels [copied from


2. Place Table and a Figure side by side.   [source:

\usepackage{capt-of}% or \usepackage{caption}

    \begin{tabular}{ l r r r }
      Student & Hours/week & Grade \\
      Ada Lovelace & 2 & A \\
      Linus Thorvalds & 8 & A \\
      Bruce Willis & 12 & F \\
      Richard Stallman & 10 & B \\
      Grace Hopper & 12 & A \\
      Alan Turing & 8 & C \\
      Bill Gates & 6 & D \\
      Steve Jobs & 4 & E \\
    \caption{Student Database}
    \captionof{figure}{2-D scatterplot of the Student Database}

Insert Latex equations and tables in Powerpoint and Keynote

At times we need to copy the Latex equations and tables in our presentation slides prepared either in Microsoft Powerpoint or Apple Keynote. There are many options to do the same but here I will explain a simple approach

  1. Ensure that LatexiT is already installed on your machine. If it is not installed download a fresh copy from this link
  2. Open LatexiT and copy the required latex equation/table from your latex file into the LatexiT editor. Make sure that you remove- begin{table}, begin{equation} type of commands.   After copying, click on LaTeX it button at bottom right to generate equations and tables
  3. Once your equation/table is drawn, save the file using from File Menu.

There are different options for customizing the output such as font size, installing new packages.

Sustainable Energy

In Oxford dictionary sustainable means “able to be maintained at a certain rate or level.”  According to the United Nations sustainability is defined as “meeting the needs of the present without compromising the ability of future generations to meet their own needs .” The important question to ask is why we are discussing sustainable energy, and the answer is either we have limited sources of energy or we are polluting our environment at the incredibly fast rate. In fact, we are facing both of these challenges, but at the consumer level, we don’t realize these.

The major sources of energy are coal, oil and natural gas. Two major problems with these resources are they are: 1) limited and are getting depleted; this means that our future generations will face energy scarcity. 2) Coal, the main energy source emit lots of carbon dioxide, a green house gas which eventually results in the greenhouse effect. The greenhouse effect deals with heating of our climate which eventually melts the glaciers raises water levels and affects global ecosystem badly.

Sustainable energy aims to find solutions to our existing energy problem by proposing renewable energy sources which regenerate naturally and produce clean energy. These sources include solar, wind, water, biogas, geothermal energy. All these sources are inexhaustible. Sustainable energy also includes the practices of energy efficiency and conservation.

Stephen Pacala, an environment biologist at Princeton University mentions that we can handle the increasing carbon dioxide challenge with following four options:

  1. Efficiency: Develop technologies or appliances which are energy efficient
  2. Tripling our nuclear power plants
  3. Cleaning coal plants by burying carbon emissions
  4. Harnessing SUN’s energy using solar panels etc.

Eigen vectors and Eigen values

A point x in a two-dimensional space represents a vector because it has a magnitude and a direction with respect to the center (0, 0). A scalar multiplication of x represents another vector which lies on the same line (elongated or scaled down) as that of vector x.  When we multiply vector x with a matrix A, it again results in a vector but now the resultant vector will be either in the same previous direction as that of x or in a new direction. Also, the resultant vector will get either scaled up or down. If the resultant vector lies in the same direction then we say vector x is Eigen vector of matrix A, otherwise, it is not an Eigen vector. A 96 seconds youtube video explains the same concept visually.

Corresponding to Eigen vector, we too get a scalar value (\lambda) which on multiplying vector x results in the same vector as that obtained by above matrix multiplication. Mathematically,

A*x =   \lambda*x

Here, x refers to Eigen Vector and \lambda refers  to Eigen value.




Installing and configuring RaZberry

Follow these steps to install RaZberry:

  1. Format memory card using SDFormatter
  2. Download OS for Raspberry and burn OS image on memory card by  using Etcher software
  3. Enable display as mentioned in this post.
  4. Connect your Raspberry to Monitor and enable following in the Raspberry configuration: VNC, SSH
  5. Install screen: This will help in running scripts in the background even when ssh session disconnects
  6. Install Z-wave using instructions mentioned on Z-wave website