Observations

Keywords:  Observations, Research Advice, Industry Future, Education, Biosensors, Solar Cells, Flexible Electronics, Percolation, machine learning, Reliability Physics

Is in-person education irrelevant?! 

I was puzzled when I first read that Socrates doubted the wisdom of "writing",  arguably the greatest invention of the human mind.  Socrates felt that "Writing is elixir not of memory, but of reminding; and it offers the appearance of wisdom, not true wisdom, for they will read many things without instruction and will therefore seem to know many things when are for the most part ignorant."  In other words, focusing on written words exclusively may preclude dialog --the Socratic method of a continual cross-examination of ideas between a teacher and a student. This deep criticism of writing applies equally well to online lectures that convey information, without an opportunity for dialog among students and professors.   A student may collect a lot of facts but may not know how to thread them or apply them to real-world problems. For that, mentorship is perhaps as relevant today as it was two thousand years ago during Socrates' time. 

Keyword: Advice

Problem-driven Research ... Insights from Bell Labs

I often tell my students that "research problems should be timely (i.e., specific topics of great current interest), but the solution timeless (i.e. a distilled essence of knowledge that travels across disciplines)."  I have discussed this perspective in several talks, (e.g.,  Computational Modeling: Experience from my Bell Lab Day , How to Write a Journal Paper).  Recently, my colleague Ali Shakouri sent me two articles that speak to this point from a broader perspective:  Venky Narayanmurthi's talk on research paradigms (https://discoveryresearch.org/events)   and Ralph Brown's article on innovation at Bell Labs (https://maceip.github.io/bell-labs-innovation/)  discuss issues of innovation and creativity in large organizations. Appropriately translated, their insights are equally relevant to  day-to-day decision-making regarding personal research. 

Keyword: Research Advice

A Great Career Advice: Ladders vs. Lattices

Apparently well-known advice,  I came across this fascinating description of the importance of broad, deep, and non-traditional experiences  while listening to a talk by  a senior executive from Eli Lilly:  "People climbing career ladders may go up faster, but people climbing career lattices may end up doing more interesting and innovative work. " Here are a few articles that discuss the topic. 

https://www.edsisolutions.com/blog/career-ladders-vs-career-lattices-tools-for-employee-development https://beleaderly.com/climbing-ladder-lattice-surprising-answer-three-women-leaders/

Keyword: Career advice

The Diffusion Puzzle in cm-Scale Bacteria, Brain, and Mold-Compounds 

We learned in high school that bacteria are microbes because we need a microscope to see these micron-sized objects.  Why are they so small, why do they not evolve to be larger? The short answer is diffusion bottleneck. It takes a small molecule an hour to diffuse 1 mm, or equivalently, 100 hours to diffuse 1 cm.  An mm-sized bacteria would be too slow to carry out its metabolic functions. They are just big enough so that all the metabolites are close at hand contained within the microscopic box defined by the cell membrane.  At least that was the theory until the giant cm-long bacteria (elegantly named Theomargarita magnifica) was discovered. How does T.  magnifica solve the diffuse problem?  J.-M. Volland offers a hypothesis (Science,  376, p. 1379, 2022; p. 1453, 2022). First, its nitrogen-filled vacuoles press all the cell machinery within a few microns of the membrane, so that nutrient uptake and waste out-diffusion are as easy as that of a small bacteria.  Second, the molecules needed for various physiological functions are distributed across the surface of the bacteria, therefore, the surface diffusion (through the micron-thick shell) rarely needs to go longer than 10s of micron. In effect, this large bacteria acts as a collection of smaller bacteria arranged on the spherical shell of the membrane.    The official of the East-India Company who ruled India would have been impressed with this "Divide (space) and Conquer (Diffusion)" strategy to manage affairs across vast lengthscales.  Indeed, the mathematics of biobarcode sensing can be used to understand the time-kinetics of these magnificent creatures. 

Nature seems to use this strategy of diffusion through restricted space in a variety of situations. For example, a (May 2022) Physics Today article "The Secret World in the Gaps Between Brain Cells," explains inter-cellular communication by molecular diffusion through extra-cellular space (ECS) within the brain. The maze-like space is defined by its porosity and tortuosity which could be just 10s of nm wide in many places. After a stroke, the swelling closes the pathways and leads to irreversible damage by preventing ion transport. Two measurement techniques, real-time iontophoresis (RTI) and integrated optical imaging (IOI),  quantify the diffusion process through the maze-line network.  

 Our work related to ion- and moisture diffusion in mold compounds seems to have many similarities to how molecules flow through the extra-cellular space. Porosity and tortuosity define the space and the physics of diffusion.  Our goal is to stop (chloride) ion diffusion and prevent bond-pad corrosion.  I am particularly intrigued by the role of dead space in the brain network that increases the tortuosity beyond \sqrt(3/2) and slows down the diffusion. I wonder if  block copolymers (used in the BEOL dielectrics) can be used to intentionally create these dead-spaces and suppress ion transport. 

Keywords: Biosensors, Reliability Physics, Observations 

How to Give a Talk: A Story by Ralph Bray

During the second world war, Prof.  Lark—Horovitz 's work on Germanium semiconductors at Purdue attracted a steady stream of top-notch scientists including Teller, Bardeen, Shockley, Weisskopf, Seitz, Lehovac, Brattain, Pearson. Unsure about Teller's background, a student asked: “At what level should I tell you about my work?” Teller replied, “Assume that I am infinitely ignorant and infinitely intelligent."  Great advice from an extraordinary man: A well-prepared, jargon-free talk that respects the audience will always be impressive. 

Keyword: Research Advice

A novelist's advice for writing a great science paper

I found the advice interesting and helpful.  

Integral of an inverse function -- A (very?) useful result ... 

Schnell and Mendoza writes in The Mathematical Gazette that for y=f(x), there is a well-known differential relation related to the inverse function:  1/f'(x) = (f^{-1})'(y), but few people realize that there is an integral formulation for the inverse function as well, namely,  \int (f^{-1}(y)dy = x f(x)- \int f(x) dx.  For example, if y=cos(x), then \int(cos^{-1}y dy = x cos(x)-sin(x) = y*cos^{-1}y - sin(cos^{-1}(y) = y*cos^{-1}y - (1-y^2)^0.5. Change the variable to x to find the integral of \int(cos^{-1}(x)!

We wanted a flying car, but we got twitter  ... Peter Theil

Technology observers such as Peter Theil has bemoaned the stagnation of technology breakthroughs over the last several decades. However,  with new mRNA vaccines, geothermal renewable energy,  self-driving cars, ultra-scaled fusion reactors,  etc. on the horizon,  a new dawn may be breaking, writes David Brooks of New York Times.  For renewable geothermal energy, the "sun under our feet"  may solve our energy needs for the foreseeable future,   David Roberts suggests in an elegant article in  Vox.    For people suffering through the 1918 influenza epidemic, it was impossible to foresee how technologies will transform and improve lives only a few decades later. Perhaps the 2019 Covid epidemic will usher in a time of comparable progress and development. 

A (Literary) Advisor ?!

When I work with a graduate student, I slowly assess what the student may need to be an independent researcher capable of reaching his/her full potential. A student comfortable with theoretical modeling may need to become comfortable in doing and understanding related experiments and vice versa, a shy student uncomfortable with public speaking may require practice and encouragement, others may need help with their writing -- most often with logical structure and overcoming the fear of a blank page.  One topic I have shied away from is any advice on is non-technical reading. In the old pre-Facebook days, foreign students were immersed among the American-born students and the informal liberal education happened by osmosis. This is no longer true. In preparing my foreign-born students for a career in America, do I have an obligation to point out the books that help one understand the uniqueness of the American experience? If so, what books should they read?  In a recent interview published in the New York Times, President Obama offers an interesting list: 

On "the top of his head, says Mr. Obama, he’d suggest Whitman’s poetry, Fitzgerald’s “The Great Gatsby,” Ellison’s “Invisible Man,” Steinbeck’s “The Grapes of Wrath,” Morrison’s “Song of Solomon,” “just about anything by Hemingway or Faulkner” and Philip Roth, whose novels capture that “sense of the tension around ethnic groups trying to assimilate, what does it mean to be American, what does it mean to be on the outside looking in?”

As for nonfiction: autobiographies of Frederick Douglass and Malcolm X, Thoreau’s “Walden,” Emerson’s “Self-Reliance,” Lincoln’s Second Inaugural Address, Dr. King’s “Letter From Birmingham Jail.” And Alexis de Tocqueville’s “Democracy in America,” which makes us remember, Mr. Obama said, “that America really was a break from the old world. It’s something we now take for granted or lose sight of, in part because a lot of modern cultures so embodies certain elements of America."

Keywords: Advice, Observations

Letter from a well-read and thoughtful colleague ....

Ashraf:

You ask, what books would help someone understand the uniqueness of the American experience. Out here in the Midwest, my list might be different from what those educated in the Ivy League schools would list.

For me, Lincoln is the real American – a self-educated product of the frontier. Could anyone be wiser or more eloquent than him?  Doris Kern Goodwin’s ”Team of Rivals” is a good place to start. Ulysses Grant was another product of the Midwest. Ron Chernow’s “Grant”, or Grant’s own “Personal Memoirs”, tell the story of this remarkable man. Also,  I’ve always thought Teddy Roosevelt’s energy illustrated the spirit of the country. Doris Kerns Goodwin’s “The Bully Pulpit” is excellent.

The pioneer’s experience is central to the American experience. Willa Cather’s masterpiece, “My Antonia,” tells the story of pioneers in Nebraska. Cather’s formative years were in Red Cloud Nebraska – a few miles from where my grandparents were farming when she wrote this book. “Song of the Lark,” which she wrote just before “My Antonia” tells the story of a girl raised in a small Colorado town who achieves artistic success as an opera singer. The idea that anyone, born anywhere in the U.S. is capable of whatever they dream of is very American. Look at Lincoln!

I recently discovered Wallace Stegner and have tried to read everything he wrote – fiction and non-fiction. He’s another example of someone who grew up in the frontier with little education or culture and became “the dean of Western writers” – although he always chafed at Eastern critics who considered him only a “regional talent.” “Big Rock Candy Mountain” tells the story of people seeking their fortune in the West. It’s considered a classic for understanding America and its rise. Stegner’s “Angle of Repose” won a Pulitzer Prize. It tells the story of a cultured woman married to a mining engineer and their life in the West. His later books, “Crossing to Safety,” “The Spectator Bird,” and “All the Little Live Things,” tell the story of a curmudgeon seeing traditional values disappear. His lecture, “The Twilight of Self-Reliance – Frontier Values and Contemporary America” says more on this. His biography of John Wesley Powell, “Beyond the Hundredth Meridian,” is more than a biography, it’s about the soul of the American West. "A River Runs Through It” by Norman Maclean is another classic about the American West. Maclean grew up in Montana and spent his life as a professor of English at the University of Chicago, and this is the only book he wrote, but his unfinished, “Young Men and Fire” is also very good.

For a book on what drives engineers in the U.S. to work so hard, there is nothing better than Tracy Kidder’s “Soul of a New Machine.” An EE professor used to assign this to a software engineering class so that the students knew what they were getting into.

That’s my random list of books about America.

Mark  Lundstrom

Keywords: Advice, Observations

On Writing Well 

Professors are professional writers: They constantly write research papers, proposals, and books. Except for the edits by their thesis supervisor and reading a few well-written papers in the field, most learn the art of writing by trial and error.  Yet, we scoff even at the suggestion of taking a formal course on writing:  We are busy, and typical writing instructors do not understand science writing.  This perspective is unfortunate because a well-written proposal has a higher probability of getting funded, and a well-written paper is more likely to be cited.  A recent American Scientist article by George Gopen titled "Getting the Point Across" (v. 110, p. 346, 2022) explains that writing improves significantly if the writer puts the most crucial information at the "stress position," namely, close to the period at the end of the sentence.  He explains how easy it is to use the three punctuation marks (period, colon, and semicolon) to create the stress positions anywhere in the sentence.  The idea is intuitively simple, and the rewards are immediate.  Gopen's website  (www.georgegopen.com) has other excellent articles, such as  "Science of Science Writing,"  "Measuring Plain English: Using Reader Expectations to Redefine Readability," "What's an Assignment Like You Doing in a Course Like This?: Writing to Learn Mathematics."  His Youtube lecture is also excellent; this is also good.  As professional writers, spending an afternoon reading these papers and listening to the lecture would be time very well-spent. 

Keywords: Advice, Observations

History of Electronics:  Purdue Stories

At the edge of the campus, an elegant life-size statue of young Neil Amstrong sits outside the building that bears his name. On the grass close-by, small children hop around in the replica of his footprints on the moon. Even a casual visitor to Purdue soon learns that this "cradle of astronauts" has produced the first and last man to land on the moon and Purdue astronauts have flown one-third of all the space missions! 

I sometimes wish that a visitor would also know about two giants of semiconductor device physics I have long admired: Ralph Bray and Mohamed Atalla. It is often said that the miracles of electronics defined the 20-th century. The century that started with the radio and telephone ended with personal computers and cellphones. This  transformation was supported by three revolutionary devices: vacuum tubes, bipolar transistors, and MOSFET. Purdue physics graduate student Ralph Bray narrowly missed out on the invention of the bipolar transistor. After his APS talk in Washington in April 1948, the Bell Labs rushed to publicize their own discovery of the transistor just months earlier in December 1947. Bell lab scientists eventually got the Nobel prize, but they acknowledged in their papers how  Ralph's work had informed their discovery.  (PBS documentary)

In 1959, Purdue alum Mohamed Atalla invented the other miracle device, the MOSFET. After completing his Ph.D. in Mechanical Engineering on "Fluid Flow in Square Diffusers", Atalla joined Bell Labs in 1949 (just months after the announcement of bipolar transistor) and was immediately drawn to semiconductor physics. In a burst of creativity within the next few years, he would invent oxide passivation, thermal oxidation, and eventually (with Dawon Kahng) the MOSFET with 20 micron channel and 100 nm gate oxide. (The transistors in our cellphones are just the scaled version of Atalla's invention, with 20 nm channel and 1nm gate oxide.) A restless visionary, Atalla soon left the semiconductor industry to work on the computer security problem. In the 1970s, he invented PIN and the Atalla box for secure bank communication. Next time you withdraw money from an ATM by punching in your PIN, it is likely that some version of the Atalla-box is securing your transaction! 

Well, we have all sorts of "statues" at Purdue: Some are immediately visible, for others you have to look a little harder!  

Keywords:  Observations, Transistors

Four Beautiful Lectures by Prof. Deleep Nair from IIT-Madras

From Elektron to Electrical Engineering This talk reviews the 2500-year-old history of electricity & magnetism until around 1880 CE when Electrical Engineering emerged as a profession.

The Story of Integrated Circuit Here the story begins circa 1880 CE and takes one of the many forks of Electrical

Engineering followed the development of solid-state electronics till the 1970s when Santa Clara Valley was renamed Silicon Valley.

The Planar Process by Jean Hoerni  In 1959, Jean Hoerni at Fairchild Semiconductor made the most important innovation in the history of the $580 billion semiconductor industry (2021 figure). He developed the planar process which made possible the manufacture of ultra-reliable transistors. It was also the all-important bridge from the transistor to the integrated circuit (IC).  In this talk, Prof. Nair discusses the historical and technical background, details of the invention, and finally how it led to the development of monolithic IC.

Semiconductor Manufacturing- Comparative Development of India, Taiwan, and Korea  The pervasive nature of semiconductors in our daily lives and the importance of East Asia in the semiconductor supply chain were realized by many only when there was a semiconductor shortage. The rise of E. Asian countries like Taiwan and South Korea from third world to the 1st world status in just over 30 years is one of the greatest stories of the 20th century. Both are smaller than the state of Tamil Nadu in area. India, Korea, and Taiwan started from similar conditions in the 1950s and yet they diverged so much. Electronics and Semiconductors played a big role in their economic transformation, which I call the 2nd divergence. In this talk, Prof. Nair reviews the history of these three nations and try to compare their development.

Keywords: History, Semiconductors

Datacenters, Solar Farms, and Implantable Sensors: Reliability and Self-Calibration of Autonomous Large Systems

Everyone knows about the first von Neumann paper on computer architecture, but we should be paying more attention to the other paper that focuses on reliability physics. In "Probabilistic Logics & Synthesis Of Reliable Organisms From Unreliable Components,"   In this paper, he writes "Our present treatment of error is unsatisfactory and ad hoc. It is the author’s conviction, voiced over many years, that error should be treated by thermodynamical methods, and be the subject of a thermodynamical theory, as information has been, by the work of L. Szilard and C. E. Shannon."  Our recent work fuses physics and information theory to address the fundamental reliability/variability of field-deployed wearable/implantable sensors. 

Transistor at 70:   Still remarkable and still surprising ... 

In the class that day, I had already drawn on the blackboard the band-diagram of a  Schottky junction diode  as well as the arrow indicating the majority carrier current flow across the junction.  I sometimes tell tidbits from the semiconductor history to keep the students awake! So I mentioned  that the first transistor (that earned Bardeen, Brattain, and Shockley the Nobel prize and started the semiconductor industry) also had  a pair of   Schottky barriers  for the emitter-base junction and the  base-collector junction.  I drew a quick energy band diagram of the point-contact transistor.  No sooner had I drawn the diagram, however, I realized that this transistor cannot possibly have a current gain!  I left the class with the embarassing  secret that even after teaching solid-state devices for 15 years,  I  still did not understand the most important experiment in the history of my field! 

Back in my office, a few  basic calculations showed that the current gain of a W-Ge-W transistor was indeed  smaller than 1.  Fortunately, the transistor was hooked up in the common-base configuration, and therefore the voltage-gain compensated the current-gain to provide an overall power-gain.  This is what the Bell Labs brass and the reporters saw in the now-famous  transistor demonstration in the 1948 New York press conference.   Had they hooked it up in a common-emitter configuration, well ... !

Rereading the  Bardeen's papers, I wonder if  he fully understood the transistor action because he  used his surface-state model to give an ad-hoc interpretation of the physics of a point-contact transistor.  I also realized that great advances can happen even if the physics is not yet fully understood.  In any case, what a remarkable device it was: Even after 70 years of its discovery,  it still has stories to tell and  power to surprise. 

For a elegantly written personal history of transistors, read R. M. Warner, Microelectronics: Its Unusual Origin and Personality, IEEE Trans. Elec. Dev. 48(11), 2457, 2001. 

Keyword: History, observation

Let us "Waste" Sensors and Transform the World by "Social Sensing"?!

As Moore's law for transistors took off in the 1970s, Carver Mead encouraged everyone to "Listen to the technology and find out what it's telling you." Presumably, Moore's law told him is to start "wasting transistors"! Gone are the days of expensive, individually tested, and gift-wrapped transistors where clever design and programming made the best use of a scarce resource. In the era of abundant, essentially-free transistors, one could use millions of transistors to do "silly" things -- like moving an arrow on a screen to click "yes" or "no" (previously done by a keyboard click Y/N). The genius of Carver Mead was to realize that "wasting" transistors is not easy, because it requires a new conceptual paradigm and design toolset, such as hardware compilers to translate CPU design directly to the underlying interconnected transistors, self-correcting inverting digital logic immune to variability and drift, place-and-route optimization for fast processing, and so on. 

Carver Mead's call to waste transistors has been on my mind recently as we have been working on printed electrochemical sensors by roll-to-roll manufacturing. Unlike the commercially-available, individually-packaged, highly-calibrated, and very expensive sensors (similar to the pre-Moore-era transistor), the R2R process produces dirt cheap sensors that cost more to test/package that to manufacture them! Who cares about a perfect, frequently calibrated sensors, when we can use quorum-sensing to produce reliable sensing based of dozens of imperfect, uncalibrated, unreliable sensors. With our ability to intelligently "waste sensors", the sensors could be liberated from the laboratory to continuously monitor without supervision analytes in people (smart healthcare), soil (smart agriculture), water (safe drinking), and/or environment (just as Moore's law liberated super-computers from the air-conditioned, glass-walled room to the billions of people across the world wielding their cellphone).  What an exciting time it is to contribute to the development of  next generation sensors. 

On the importance of skepticism 

Great scientists are visionaries and dreamers.  But visions and dreams can sometimes mislead. The author of the Principia,  Sir Issac Newton, spent several years of his life working on alchemy.   Today, Quantum computing, Mapping of the Brain,  Molecular Electronics are important topics of research. Notneheless, we will do well to listen and respond to the skeptics who make  reasoned arguments about the challenges ahead.  

The case against Quantum Computing by Mikhail Dyakonov

Read the fine print  by Scott Aaronson    

What's wrong with the brain-initiative proposals by Partha Mitra

What’s in Brian’s Brain? American Scientist, 101(4), 256-259, 2013. 

The Long History of Molecular Electronics    by H. Choi and CCM Mody

Molecular Electronics will change everything  in Wired Magazine 

The trouble with physics  by Lee Smolin

Lost in Math: How beauty leads physics astray  by Sabine Hossenfelder 

We have been here before ....  A hopeful  story of renewable resources 

Quick: Name a energy-related product for which countries are willing to go to war,  impose trade-embargo,   pass legislations to allow drilling, and send companies around the globe to find new deposits? If you answered "oil," you are right, obviously. But if you said bird-dropping (Quano), you will be right too!  

This year, Purdue is celebrating 150 years of its founding. In 1869, the world was  a very different place.  The population was rising and agriculture was booming,  but the soil  fertility around the world was collapsing.  Since the early days of the Spanish conquest, there was a rumor that Incas in Peru used a fertilizer so effective that they can get astounding yield in the same soil year after year (no crop rotation necessary).  The secret fertilizer turned out to be Quano.  The world could not get enough of it: it became Peru's main export for 30 years, its neighbors fought wars over it. In 1856, the Quano Act ensured that any quano-containing islands not yet claimed will be the property of the USA.  People soon realized that Quano contains nitrogen, phosphate, and potassium,  soil ingredients plants need.   Unfortunately, as is the case for other non-renewable natural resources, within 50 years the Quano supply was exhausted, the ecology of the islands permanently changed, and the economies that depended on it collapsed. 

In the mean time, however, the science of Quano helped scientists to look for a renewable alternative.  By 1910,  Harber-Bosch process began producing ammonia  (from nitrogen in the air) on an industrial scale. Today,  these "renewable"  fertilizers have quadrupled food production, so that only 15% of the land area feeds a population of 7 billion.  The story  gives me hope that modern-day Quano (aka oil) may give us sufficient time  to develop renewable alternatives (e.g. solar and wind) so that the world will prosper even after oil is long gone. When in 2169 Purdue celebrates its 300-year anniversary,  perhaps  people would regale in the story of oil the same way we now recall the story of Quano. 

Keywords: Obervations, Solar Cells, Industry Future

The sky is NOT falling ... 

The newspapers are full of stories of impending doom: Artificial Intelligence is taking over,  algorithm of search engines are biased and tools of oppression, Facebook is selling user data and companies are tracking our positions,  the children are forgetting to read, and it is easier to talk to the person across the world than to the neighbor across the street.  Perhaps we are living in a world of unintended consequences of digital revolution. 

And yet it is likely that we underestimate the positives and miracle of modern life.   I came to this conclusion after reading three deeply thoughtful books: Outnumbered by David Sumpter,  Factfulness by Hans Rosling, and Enlightenment Now by Steven Pinker.   Rosling and Pinker both use compelling statistics to show that the world has become a much better place over the last fifty years (perhaps the best it has ever been in the history of civilization), with hundreds of millions of people escaping extreme poverty,   child mortality is down significantly, life expectancy is at its all time high, and so on.  On the other hand,  David Sumpter elegantly argues that the algorithms are nowhere near as powerful as they claim to be and the limits of the information technology are already being tested in many applications.  

It appears that the sky is not falling (not yet at least!) and those who know actually become optimists!

Keywords: Observations, Industry Future

Power of analogies .... MEMS and Power Grids

I love analogies because analogies connect unrelated ideas and inspire new ones.  For example,  the physics of heat and particle diffusion,  Poisson equation, scalar stress field, etc.  are all described by a simple second order differential equation. You just to need to understand one problem deeply. Then, the physics of the lightning rod will guide you through the stress concentration at the crack-tip in fracture mechanics, the improved sensitivity of a nanowire sensor, the thermal shunts, and dummy-via to release heat diffusion bottleneck.   Just rename the variables, the standard solution in one field will become the talk-of-the-town in another field.  

Recently, I was reading  a Physics Today article by Scott Backhaus and Michael Chertkov titled "Getting a Grip on the Electrical Grid ."  The physics is beautiful and they use the Swing Equation for the phase to describe the phase-space of grid stability:  a local minimum defines a stable operation and a global minimum associated with the catastrophic voltage collapse.  I had a vague feeling that I must have seen this before -- no sooner I saw Fig. 2, I remembered.  The swing equation is just the position stability equation for a MEMS cantilever (with phase theta replaced by displacement y).  The local equilibrium is just the stabilized MEMS position within the first third of the gap; voltage collapse is equivalent to MEMS pull-in.  PV/wind can create transient collapse, just as a sudden electrostatic pulse can lead to transient pull-in.  Now, MEMS's travel/stability by reconfiguring the electrodes; can the same be done for electrical grids?  

Keywords: Observation, Phase transition

2018 EDS  Education Award: Acceptance Comments

I left Bell Labs confident that I knew semiconductor devices and reliability physics.  My students at Purdue, however, soon disabused of any ego I had with these “naïve” questions: 

"You said that a periodic Kronig-Penny model is necessary for  a bandgap, then how does an amorphous material develop a bandgap?  The derivation of Fermi-Dirac statistics does not account for Coulomb repulsion. Can you explain?  LED wavelengths are visible and vision evolved from the sun, then why are the energy peaks so dramatically different?  An infinite junction solar cell is exactly twice as efficient as a single junction cell. Coincidence? How is it possible that an NW-biosensor is  a thousandfold  more sensitive compared to a planar sensor, while the depleted charges are essentially the same, equal to the biomolecules?"

These “naïve” questions made me appreciate the essential difference between Schrodinger and Maxwell equations, Fock-space and renormalization of many-body interaction, the role of evolutionary biology, the geometry of PV thermodynamics, and the geometry of diffusion.  Some of my most original research contributions have been inspired by the questions I could not answer in class. 

I am grateful to the high-school teachers in Bangladesh who instilled my love for learning. I am grateful to my wife, Salmina Sadeq, for giving up her job and agreeing to move to Purdue to allow me to pursue this life of teaching and research.  And I dedicate this award to my colleague and friend  Gene Baraff and  Mark Lundstrom who taught me by their examples that teaching begins when you stop talking and start listening. Thank you.

Keyword: Research Advice

Machine Learning: Ptolemy vs. Newton 

I am teaching a course on data analysis and design of experiments, with a few lectures on the essence of machine learning. Machine learning has been used by Google, Amazon, Netflix, Facebook  for advertisement and recommendation systems.  One wonders if the approach could generalize to physics and engineering problems.  

We should be careful .... 

Machine learning is like Ptolemy's model of the solar system: highly accurate, but fundamentally wrong.  Given the "training data" collected by Greek astronomers over a  thousand years,  Ptolemy  model could fit the existing data very accurately.  In fact, planetariums still use the Ptolemy's cycle-epicycle model to project the night sky accurately.   Despite the accuracy,  NASA is well advised not to launch Juno spacecraft to Jupiter using the  Ptolemy "prediction".   The issue is that physics is all about large scale extrapolation: from a falling apple to the trajectory of the Haley's comet.  There, Ptolemy is not enough, we need  Newton.  Thus, to me Machine Learning is very useful (as Ptolemy's model was) but it should serve as a starting point for discovering the underlying physics of complex, emergent systems.  If Machine learning prompts many future Newtons (ok, nano-Newtons) to step forward and transform their fields, then it will have done its job.  Until then, let us not put away our mechanics or circuits books.  

Keywords: Observations, Education, machine learning

To see a World in a Grain of Sand And a Heaven in a Wild Flower ...

I first read the line  by  from Robert Blake almost 40 years ago and it has stayed with me ever since.   Recently, I was waiting to catch my plane at the Colorado airport, I  began reading the  book  "Storm in a Teacup: The Physics of Everyday Life"  by Helen Czerski.    As I turned the pages,  the 40-years in between just vanished and it felt like I was rereading Robert Blake all over again, but now in a different context. The ability of see the extraordinary in the ordinary  is a rare gift and to be able to write about it so elegantly is rarer skill.  Helen's book reminds me that deep beauty is all around us, including in the teacup we hold, provided we appreciate the physics, chemistry, and biology of everyday life. 

Keywords: Observations

The ideal design:  How to Solve Tomorrow's Crisis ... Today

Here is a Bell Lab story that explains the power of strategic system-oriented thinking  and the effect a visionary leader can have. 

Keywords: Industry Future, Education

Dielectric breakdown with a twist ... 

When I teach reliability physics, I explain that the thin oxides have long lifetime in part because the defect generation is uncorrelated. This is fortunate and extraordinary. Despite the superficial similarity with dielectric breakdown, mechanical fracture is generally correlated.  A remarkable example is the fracture of a pasta noodle, which fracture under stress at least in three pieces because the fracture energy released from one break propagates through the remaining the remaining tube to break the noodle a second time. This PNAS paper explains how  one can break the noodle into two pieces by stopping the energy propagation by twisting the noodle. 

Keywords:  Reliability Physics

The (renewable) sources of energy in the USA

Wind mills have really made a difference in some states, but solar energy less so ... 

https://www.nytimes.com/interactive/2018/12/24/climate/how-electricity-generation-changed-in-your-state.html?action=click&module=Top%20Stories&pgtype=Homepage

Keywords: Industry Future, Solar Cells

Touching the face of the sun ... 

Yesterday, the Parker Solar Probe left the earth for its seven-year journey to the sun. The probe is named after Dr. Eugene Parker at the University of Chicago who predicted the existence of solar winds in a short paper in Astrophysical Journal.  The solar wind consists of the charged particles ejected from the sun that reach the outer boundary of the solar system. The paper was simple (only a few lines of math), yet so extraordinary that the reviewers rejected it outright. The editor Dr. S.  Chandrasekhar overturned the reviews and published the paper.  By 1962, as Mariner 2 traveled to Venus, the measurements proved Dr. Parker right. The space-probe is a tribute to this extraordinary physicist.  

Keywords: Observations,  Solar Cells

The 1996 Altantic Montly article "Shipping Out " ...

by David Foster Wallace  provides one of the finest example of honest and precise writing.  Whether writing about a luxury cruise or about recent research finding, Wallace shows how to engage one's attention with detailed observation and vivid, authentic writing.  The article is long, but each sentence acts as a brushstroke of a giant canvass, interesting and insightful on their own. 

Keywords: Observation, education

At 2018 IPFA meeting  at Singapore ...

For the semiconductor experts,  the transistors have become  an abstract (almost mathematical) concept hidden underneath the black plastic cover of an IC. Yes, we know that the channel has shrunk to 10nm. If we break a large modern IC, we can give everyone in the planet one transistor, with a few leftover.  The number of transistors produced in a year is larger than the number of leaves in trees worldwide.  We are told that transistor channels are just 40-50 atoms long. A bacteria could carry of tens of these transistors without knowing that they are there.    I often feel that  none of these analogies are effective because they compare things for which we do not have an intuitive appreciation. 

For me, the images presented at IPFA changed all that.  The 3D X-ray  and acoustic tomography images brought into vivid relief the miniaturized  3D "city" of  bond pads, interconnects, and transistors that make a modern IC work. The TEM and SEM pictures that show the multitude of nm-thin layers of a transistor is mesmerizing.  These images reminded me of the miracle of modern ICs. 

The physics underlying the instruments used for failure analysis are astoundingly diverse and sophisticated.  IC fabrication is a truly collaborative effort -- every branch of physics and chemistry have contributed to make it work.  Next time I teach, I am going to pay homage to the unsung heroes of failure analysis in the first day of the class. 

Keywords: Observations,  Education,  Electronics, Percolation

HfO2, the new miracle material? 

I used to tell my students that Si is the miracle material,  given its ubiquitious use in modern electronics and availability of SiO2 as the native oxide.  More recently, I am beginning to think that the top honor could also go to HfO2: It saved Si technology once as a high-k dielectric, it may do so again as a ferroelectric/antiferroelectric negative capacitor for NCFET, and it works as resistive RAM memory for machine learning ICs.  

A wonderful life .... 

A wise and thoughtful article Prof. K. R. Sreenivasan on "A Life in Teaching and Turbulance."  What he says specifically about turbulance and personal interaction actually applies more broadly to other topics of science and engineering. 

Also,  Fred Rogers  had a favorite maxim, “deep and simple is far more essential than shallow and complex.”

Keywords: Observations, Education

The Unreasonable Effectiveness of Mathematics in the Natural Sciences ...

... was the title of an article published in 1960 by the physicist Eugene Wigner.  His point was  that there is no rational explanation for this gift that we neither undersand nor deserve.  An analogy by Stanislaw Lem helps demystify the math-physics correspondence . Consider a crazy tailor who has never interacted with a human, or a plant, or an animal. He simply makes random clothes, with different holes for the hands and legs and tubes for the body. The clothes are stored in a giant, free warehouse.  Anyone stopping by  -- a gurilla or an octopus --   will find something in the warehouse that fits. That's how math works. Mathematicians make structure without knowing/caring about applications.  If it applies to a problem, that is wonderful. This "survival of the fittest" theory obviates invoking the miraculous. 

Keywords: Observations, Education

Swarm Electrification for Solar 

Off-grid PV is inefficient. Since the battery is expensive, therefore one uses just enough storage for an average day . On a bright day, more than 30% of the energy is wasted. SOLshare is a Dhaka-based startup that connects these isolated systems into a mini DC grid through a device called SOLboxes.  Its hardware allows cable connection and its software tracks the energy transaction and billing.  For other success stories regarding minigrid, see a recent newsarticle. 

Keywords: Solar cells, Industry Future

Wheeler's  Rules of Writing :    https://aapt.scitation.org/doi/10.1119/1.19169   Read the footnote too!

Keyword. Research Advice

Four New Ways to Compute .... 

A recent article in IEEE Spectrum discusses four new ways to compute using: Quantum computers, Neuromorphic computers, Computing with wires, and evolving electronics. Computing with wires implement logic using the interconnected backend. Evolving electronics uses CNT percolating network and a collection of electrodes to do certain classification problem (Paper) 

Keyword: Observation, Industry Future, Percolation

The power of Nondimensionalized Model. 

 Nondimensionalized  models produce  physically universal and numericlly robust results.   For example, a vaiety of numbers (e.g. Reynold's number, Biot number, etc. )  arise from nondimensionalized  Navier-Strokes equation. The approach is directly related to Buckingham Pi theorem.  The topic is easily learned from the following articles.   

ODE: https://en.wikipedia.org/wiki/Nondimensionalization

PDE: https://link.springer.com/article/10.1007/s11071-015-2233-8

Examples: https://user.engineering.uiowa.edu/~fluids/Posting/Schedule/Example/Dimensional%20Analysis_11-03-2014.pdf

Coupled Equation: https://math.stackexchange.com/questions/845891/nondimensionalization-of-coupled-ode 

References: R. W. Robinett, "Dimensional Analysis at the Other Language of Physics," American Journal of Physics, 83(4), 353, 2015. 

History of Land Grant Universities

I have been at Purdue since 2004,  yet I did not fully appreciate the history and the mission of a  land grant university such as Purdue, until I read this article by Prof.  Neil E. Harl.  I thought incorrectly  that  President Lincoln was the visionary who proposed this idea. In fact, the visionary leader was Vermont congressman  Justin Morill who was a tireless and dogged  advocate for the idea. In 1862,  Lincoln signed The Morrill Act into law. The act was broadened by the Hatch Act (1887) and Smith-Lever act (1914).  The law envisions a land grant univeristy system  that  makes education accessible to all  and takes teaching, extension, and research as  three pillars of core mission. Prof. Harl suggests that we have sacrificed teaching and extension for research.  He blames the pursuit of ranking, prestige among peers, and industrial funding  for this unfortunate shift from the core mission.  This shift has severed the connection  to the real world problems and reduced our impact.  He suggests  that we reconsider the direction we are headed .... and I think it is about time we do so. 

Keyword: Observations, Education

Machine Learning -- Concepts Made Easy 

The basic concepts of machine learning is nicely explained in this elegant tutorial  (http://playground.tensorflow.org/).   The  concepts become crystal clear if you play this game for a few minutes.  The short course from google is also excellent, delivered in snall bites and with frequent quizzes to ensure learning. To understand the technical details, one needs to know few mapping functions (e.g. sigmoid) -- which is explained nicely explained in Nathan Brixius's article.  And the proof that neural network can compute any function is shown here in Neilson's introduction.  Other simple explanation connecting digital logic and machine learning is posted here.  Prof. Raj explains the connection more deeply.  If you have forgotten Karnaugh mapping, the youtube lectures can help. 

Keywords:  Education

Big Data and Machine Learning in the PV Industry

I found the following blogs from NextTracker -- a PV software company -- interesting. 

https://www.nextracker.com/2018/03/turning-data-into-action-for-solar-power-plant-owners/

https://www.nextracker.com/CloudisGood 

Although the focus is on data-enabled  operation and  maintenance, it is easy to see how much more could be done with the information provided. 

Keywords: Industry Future, Solar Cells

The little  "grapefruit" that could ... 

Khrushchev  derided  Vanguard 1 -- a aluminum sphere weighing only  1.46kg --  as a grapefruit satellite, but its successful launch  in March 1958 restored American national confidence.   One of the most interesting innovation was the use of  six monocrystalline silicon solar cells ( total area :150 cm2,  ouptut :1W, efficiency ~ 6%) that  continued to power the satellite for years before it fell silent in May 1964. The technology was invented just  four years earlier at Bell Labs in 1954 (Hans Ziegler of US Army overcame the steneous objection from the NAVY to include this 300 dollars per Watt technology) . Today the silent satellite continues to orbit the earth ( approaching ~200k revolutions ) and it will  to do so for another 200 years.  The solar cells do not work anymore, but their memory lives on in the success of the worldwide PV industry (331 TWh in 2016 and counting). 

Keywords: Obervations, Solar Cells

Machine Learning and Social Science

Historically,  social scientists and psychologists  have used small-scale, thoughtful experiments for glimpses into the motivations that drive our actions. With right experimental design, the results can be deeply insightful: consider the work of Stanley Milgram and Daniel Kahneman. More often than not,  the small sample size and the artificial setup have led to conclusions that could not be replicated.  Some of the foundational results in the field have been challenged.  Fortunately, the field is now being transformed by the abundance of data from Google, Amazon, Netflix, and other data companies.   Our clicks expose our souls better  than any survey question ever could. For  an interesting recent application, see  Physics Today article "Sociophysics" by Frank Schweitzer regarding the invasive percolation model for cultural diffusion, and a recent PNAS paper by  AD Pananos regarding the phase transition model of the relationship between vaccination and spread of epidemics. 

Keywords: Observations, Percolation, Phase transition

Elegant writing by scientists

The earth would look like "a pale blue dot" from the vantage point of someone who has traveled just a few light-days away.    American astronomer Carl Sagan writes: 

“Look again at that dot. That's here. That's home. That's us. On it everyone you love, everyone you know, everyone you ever heard of, every human being who ever was, lived out their lives. The aggregate of our joy and suffering, thousands of confident religions, ideologies, and economic doctrines, every hunter and forager, every hero and coward, every creator and destroyer of civilization, every king and peasant, every young couple in love, every mother and father, hopeful child, inventor and explorer, every teacher of morals, every corrupt politician, every "superstar," every "supreme leader," every saint and sinner in the history of our species lived there-on a mote of dust suspended in a sunbeam.

The Earth is a very small stage in a vast cosmic arena. Think of the endless cruelties visited by the inhabitants of one corner of this pixel on the scarcely distinguishable inhabitants of some other corner, how frequent their misunderstandings, how eager they are to kill one another, how fervent their hatreds. Think of the rivers of blood spilled by all those generals and emperors so that, in glory and triumph, they could become the momentary masters of a fraction of a dot.

Our posturings, our imagined self-importance, the delusion that we have some privileged position in the Universe, are challenged by this point of pale light. Our planet is a lonely speck in the great enveloping cosmic dark. In our obscurity, in all this vastness, there is no hint that help will come from elsewhere to save us from ourselves.

The Earth is the only world known so far to harbor life. There is nowhere else, at least in the near future, to which our species could migrate. Visit, yes. Settle, not yet. Like it or not, for the moment the Earth is where we make our stand.

It has been said that astronomy is a humbling and character-building experience. There is perhaps no better demonstration of the folly of human conceits than this distant image of our tiny world. To me, it underscores our responsibility to deal more kindly with one another, and to preserve and cherish the pale blue dot, the only home we've ever known.”

Keywords: Education, Observation

Google Trends: A rich source of data (and perhaps information)

Big data is big -- it is a topic of much enthusiam (and some skepticism.) Our keystrokes, voice messages,  camera pictures, gps locations, etc. act as always-on sensors of our thoughts and actions., revealing to google what we would not share with our closest friends. The torrent of data produced can be analyzed for information.  Type in the topic you are interested in and googletrends will tell you how the search for the term has evolved since 2004. If you wish to dive deeper,  you can download the data for further analysis. 

It costs less to make a brand new PV farm than to keep operating an old coal power plant ....

https://www.nytimes.com/2018/02/06/opinion/utility-embracing-wind-solar.html?action=click&pgtype=Homepage&clickSource=story-heading&module=opinion-c-col-left-region&region=opinion-c-col-left-region&WT.nav=opinion-c-col-left-region

Silk cools radiatively by using the atmospheric IR window 

Glass cools radiatively and so does silk, but apparently with a very different mechanism. 

see. https://www.nature.com/articles/s41467-017-02500-5

Keywords: Biophysics, Solar Cells

Nature is topological

APS News referred to these two intersting articles:  A paper by Shanker in PRX (DOI:10.1103/PhysRevX.7.031039) explains  how bacteria colony may use topological modes to transport biochemical signals. Another paper by Delplace in Science (DOI: 10.1126/Science/aan8819) shows that special types of ocean waves can travel through long distances by being topologially protected. 

Keywords: Physics, Observations

Being Mortal by Atul Gawande ... Thinking about the role of Engineers in Responding to a Social Crisis

Over the Thanksgiving weekend, I read this deeply moving book regarding how we live and how we die. Medicine has helped  prolong life, but the focus on life has left us profoundly unprepared for death.  Deeply impersonal nursing homes and old homes have become a portal for exiting the world, away from family and friends and the home we have always known.  Impersonal aggressive treatments with questionable benefits and very little input from the patients rob the last days of the life of a modicum of control or dignity. We treat because we can, not because we should.  A recent NYTimes article  describes a similar lonely end-of-life for the old people in Japan.  As a community, we are working on biosensors and wearable electronics: I wonder if engineers have any role to play in this emerging social crisis? 

Keyword: Observations, Biosensors, Flexible Electronics 

Shortest paper  in PRL  by F. Lenz, Phys. Rev. 82, 554 (1951).  It has 2 sentences, 27 words, 1 equation, 1 reference. 

It reads as follows: The most exact value at present for the ratio of proton to electron mass is mp/me=1836.15267389(17). Despite years of experimental improvements, that number still coincides, to good approximation, with the simple, unambiguous representation of 6 pi^5. 

Keyword: Obvervations

Fact vs. Fiction in solar cells

A careful measurement of efficiency is essential for the future of solar energy. The following article provides an interesting perspective

https://spectrum.ieee.org/energy/renewables/solarcell-squabble

Keyword: Solar Cells

Solar Energy harvesting from the Moon ?!

a-Si Modules could be manufactured at Moon itself -- A NASA TM  102102 by G. A. Landis (https://goo.gl/uRF5vd)  And this is one way the energy could be microwaved back to Earth. Not practical perhaps, but an interesting idea nonetheless!

Keyword: Solar Cells

Things are changing ... 

Driven by the requirements of platform companies. See 

What's Next for Transistors and What Does an AI Chip Look Like 

Keyword: Industry Future

A new meaning of nano-bio ...

A paper by Lepore et al. in 2D Materials demonstrate that  a spider that feeds on nanotubes and graphene-flakes produces stronger-than-natural silk. One wonders what the electro-thermal properties of these films be.

Keyword: Biosensors

Design of a solar farm ... catching a moving object

Recently,  Xingshu Sun -- a student in my group  -- noticed something strange regarding the orientation of  the solar panels close to Indianapolis airport.  Tahir Patel -- another student -- downloaded the google satellite image to show that some have been oriented N-S (natural for the northern hemisphere), but others across the street are oriented E-W -- which did not make sense.  Except it does! The E-W farms are on single axis tracker for which it is the standard orientation.  

It reminds me the very different strategies sunflowers take for looking at the sun. Young sunflowers track the sun East to West, because they need a lot of energy and despite the energy cost of tracking, they come out ahead. As they get older, they stop tracking and settle on a fixed tilt (typically East).

Keyword: Solar Cells

Hamming on "You and your research" ... How to define interesting problems

In 1995, Hamming recorded a set of lectures on the topic. He is infinitely interesting and relevant to the work we do everyday

https://www.youtube.com/playlist?list=PL2FF649D0C4407B30

The original article is posted here: http://www.cs.virginia.edu/~robins/YouAndYourResearch.pdf

Another related article: http://ieeecss.org/CSM/library/1999/feb1999/03-studentguidetoresearch.pdf

Here is how to define important research questions: https://dl.acm.org/citation.cfm?id=2043170

And, my talk on writing a research paper: https://www.youtube.com/watch?v=SpVVvKeUQFo

Keyword: Research Advice

Guessing takes courage: be brave, guess ...

Lawrance Weinstein: Guesstimation http://www.phy.ohiou.edu/~osaps13/osaps2013-Weinstein.pdf

Wikipedia: Back-of-the-envelop Problems:  https://en.wikipedia.org/wiki/Back-of-the-envelope_calculation

C. Swartz, Back of the envelop physics. 

S. Mahajan, "The Art of Insight in Science and Engineering: Mastering Complexity"

A. Santos, "How many licks ... "

Another interesting book is http://www.inference.org.uk/sanjoy/oom/book-letter.pdf 

Keyword: Research Advice 

Making figures, extracting data, creating library....

How do you take a ppt file and convert each slide into a separate PDF file, with all the white space removed? 

Use these three simple steps: 

1) Save the ppt file as a pdf file.      

2) Go to http://croppdf.com/ and upload the file. The whitespaces around the figures will be  removed. The file will now be called "... cropped.pdf"

3) Next, go to  https://www.splitpdf.com/, upload "... cropped pdf", select "Extract all pages into separate files", and define the label for the files (e.g. Slide) so that the output files are called Slide1, Slide2, etc. Now "Split" and get the files in a zip folder. The figures are now ready to be integrated with a book or a thesis. 

4) The following program automatically extracts data from a PNG (graphics) or jpeg (photo-heavy) plot

http://arohatgi.info/WebPlotDigitizer/   or,  http://arohatgi.info/WebPlotDigitizer/app/? 

5) Sometimes we need to convert a list of references to a BibTeX or endnote format. The following web-enabled software does it in minutes  http://git.macropus.org/citation-finder/ 

6)  Image creators: Biorender.com, https://www.circuit-diagram.org/editor/ 

Keyword: Research Advice, Tools

Why software companies are getting into chip making ... 

https://www.wired.com/story/the-rise-of-ai-is-forcing-google-and-microsoft-to-become-chipmakers 

Keywords: Industry trends

Feynman's lectures are online, beautifully rendered .. 

Always, always a pleasure to read Feynman. No matter how many times you read the notes, they always appear fresh, brimming with insights and surprises. What a wonderful resource. http://www.feynmanlectures.caltech.edu

Someday, I will make a list of "Feynman-like" books I have read over the years. Not as good, not as grand, but still sparkling with surprises and insights.  

Keyword: Education

A new book on Claude Shannon finally gives the scientist his due 

https://medium.com/the-mission/10-000-hours-with-claude-shannon-12-lessons-on-life-and-learning-from-a-genius-e8b9297bee8f

Keyword: Education

Good advice regarding writing papers, getting hired, and interesting topics ...

ACS publications has a new site called ACS Axial (http://axial.acs.org/). The articles are brief, but provide thoughtful commentary on wide variety of topics. 

Keyword: Research advice

Faculty Jobs are difficult to get, and ...

the application process can be confusing. Karen Kelsky's book "Professor is In" gives thoughtful advice. I may not agree with everything she says, but  overall the book is very helpful. 

Keyword: Research Advice

There is Plenty of Room at the Top!

• System vision for sustainable farming: http://biosense.rs/?page_id=7743&lang=en

• Driveless autonomous car: Intel buys Mobileye, a vision software company that works with 27 car company (http://www.cnbc.com/2017/03/14/intels-15-billion-purchase-of-mobileye-shakes-up-driverless-car-sector.html)

Keyword: Industry trends

A Short History of  Solar Energy

Photovoltaics may be new, but from the discovery of agriculture to bottle sunlight in crops,  to  the use of glass windows to heat the Roman homes, to the use of lens to concentrate sunlight for cooking, and the use of mirrors to burn the gathering enemy ships, etc. there have been endless attempts to use the solar energy for variety of applications.  

Inforgraphic on Solar Cells

Keyword: Education, Solar cells

The Strange Physics of Diffusion

The physics of diffusion is infinitely fascinating and continues to produce unexpected results. Consider a mixture of small and large spheres contained within an evaporating droplet. Remarkably, the large spheres always ends up in the bottom and the following paper explains why http://physics.aps.org/synopsis-for/10.1103/PhysRevLett.118.108002    There is an analogous explanation why an evaporating droplet pushes the smaller particles close to the edge -- and the larger particles are arranged sequentially inward. 

Keyword: Education, biosensors

A Modern Industrial Job -- Versatile Candidates Needed

Here is an excerpt from a recent job posting.  Here are some of the qualities the employer is looking for. 

• Experience in semiconductor packaging, solid mechanics, or related fields. (Theory)

• Good knowledge in semiconductor processing and associated materials.  (Fabrication)

• Familiarity with a range of imaging and analytical lab test equipment such as acoustic and x-ray imaging, SEM/ EDX/TEM/EEL techniques  (Characterization)

• Experience programming with formal language (C,C++) and a scripting language (AWK, PERL, Python, SQL, TCL).  (Software skill)

• Experience in empirical data collection and statistical data analysis, reliability statistics, and design of experiments (Statistical Analysis)

• Excellent communication skills, both written and verbal. High quality work, with attention to details. Capable of driving multiple projects independently and simultaneously.  Ability to become a strong team contributor as well as an individual contributor. (Soft skills) 

It is remarkable how versatile a candidate has to be to succeed in a modern industry! 

Keyword: Research advice

The Road Taken by H. Petroski

I find Henri Petroski's take on roads, bridges, and buildings delightful.  As I am reading this book, I am waking up to the engineering marvel of the road I take to work everyday. So mundane, yet so elegant.   Industrial Landscape by Brian Hayes  is similarly compelling. I wish these were the required reading for first-year engineering students. 

Keyword: Education, general

A (truly) Novel Statistics Book!  Andy Field: The Adventure in Statistics

Who says that statistics is dry ..... http://www.americanscientist.org/bookshelf/pub/stats-and-fiction

Keyword: Education, statistics

One may spend a lifetime to ...

...understand the biophysics of  a simple bacteria. Many of the things that we thought we knew  are actually wrong 

https://www.sciencedaily.com/releases/2014/05/140512155021.htm?utm_source=TrendMD&utm_medium=cpc&utm_campaign=ScienceDaily_TrendMD_1

Keyword: Education, biophysics

Droplets continue to surprise and other interesting papers ...

Water-in-oil droplets can be used a model for plant cells by decorating the water-oil interface with lipid bilayers. This is an emerging trend, using microfluidic systems to emulate various natural sensors, such as sweat grand or blood-brain barrier  AIP Biofludics publishes many interesting papers on related topics. 

If anyone interested in economics of small midwestern cities, this would be an interesting read ...

https://www.cicpindiana.com/wp-content/uploads/2016/08/Strategic-Plan-for-Economic-and-Community-Prosperity-in-the-Wabash-Heartland-Region-FINAL-7-5-2016.pdf

Interesting  books ... 

Life of Galileo by Bertott Brecht; In the matter of Oppenheimer by H. Kipphardt;   Fall Hall and the German Atomic Project of WWII by D. Cassidy,  Cosmology for the Curious D. Perlov and A. Vilenkin,   Fundamentals of Quantum Mechanics by T. Norsen, Cybersecurity of IOT by Kevin Fu, The Human Cost of Energy by M. Fischelli,  One Fluid Theory of Electricity by Benjamin Franklin,  Topology of n vs. p type semiconductor by S. Simayi and H. Takato;  Advice to a Young Scientist by P. B. Medawar,  The Art of the Soluble by P.B. Medawar;  The Places in Between by Roy Stewart; Fearful Symmetry -- Is God a geometer by Ian Stewart ; Catastrophe Theory and Its Applications; Letters to a Young Mathematian;  Erwin Schrodinger and the Quantum Revolution, John Gribbin. Ordinary Geniuses: Max Delbruck, George Gamow, a the Origins of Geomomics and Big Bang Theory" by M. Segre.

 Interesting authors

Carlo Rovelli, Ben Goldacre, Ian Stewart, Helen Czerski, Daniel Kahneman, Jordan Ellenberg, Tim Hartford, Brian Cox, Matt Ridley, Martin Gardner, Susan Greenfield, Steve Jones, Simon Singh, Hannah Fry, Steven Levitt, Nassim Taleb, Steven Pinker, Richard Dawkins, Nate Silver, Ed Yong, Alex Bellos, Phillip Ball, James Gleick, Steven Strogatz, Brian Green. 

Paper-based sensors and paper-folding by Origami and Kirigami

I wonder if it is possible to connect the two areas and create a theory of paper-sensors by mapping the time sequence of sensor reactions to the spatial sequence of an origami.  

Glucose sensors used a paper stripe to guide the blood to the reaction chamber.  Paper diagnostics (popularized by George Whitesides, Paul Yager)  generalizes the concept to multiple reagents, multiple reactions, and multiple end-products.  In contrast Origami involves paper folding for foldscope (Manu Prakash, Stanford) or paper robotics (Purdue). I find the simplicity of origami mathematics, as described by Robert Lang (https://www.youtube.com/watch?v=NYKcOFQCeno) and Erik Demaine (http://erikdemaine.org/). And here is a documentary (Between the fold: https://www.vanessagould.com/between-the-folds).  

How to start: Classify the paper-sensor reactions (e.g. time-delays ... one fold; braching ... two folds; etc.) Then map the information into basic fold-physics of origami. 

References:  (1) MIT Review  (https://www.technologyreview.com/s/419747/multistep-diagnostics-on-paper/) (2) http://www2.technologyreview.com/news/412187/tr10-paper-diagnostics/ (3) Paul Yager's work (https://bioe.uw.edu/portfolio-items/yager/) (4) Scientific American (https://www.scientificamerican.com/article/paper-diagnostic-tests-could-save-thousands-of-lives/) (5) NY Times: (https://www.nytimes.com/2005/02/15/science/origami-as-the-shape-of-things-to-come.html) (5) Origami and paper-folding: http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.466.6340&rep=rep1&type=pdf  (6) Review ... Turning a page: DOI: 10.1021/acs.chemrev.7b00024 Chem. Rev. 2017, 117, 8447−8480

Geometry and Physics

Kepler's music of the heavens based on the data from Tycho Brache:  The ratio of aximum and minimum angular speed : 4:5  for Saturn (major third), 5:6 for Jupitar (minor third); 2:3  (perfect fifth) for Mars, 24:25 for  Venus, and 15:16 for Earth.  Some thought that the secret to the universe depends on our ability to decode the planatery ochestra!  [J. R. Voelkel (1995), The music of the heavens: Kepler's harmonic astronomy," Physics Today 48(6), 59-60. 

Solar cells made easy ...

As engineers, we fuss about the details.  However, as the following videos show, big pictures simply explained can help as well. 

 https://www.youtube.com/watch?v=TqVRNupPmNI  ? 

 https://www.youtube.com/watch?v=TCq0K3DlFdc

https://www.youtube.com/watch?v=xM-uV_OSoG8

https://www.youtube.com/watch?v=xM-uV_OSoG8

Elegant work aries from asking deeply interesting questions

Itai Kohen on mechanics of fruit-fly,  Ahmad Rafsanjani on Origami, ..... 

All graduate students know the fable of "Rabbit's PhD Thesis

The moral is: "The title of your thesis doesn't matter. The subject doesn't matter. The research doesn't matter. All that matters is who your advisor is." A pretty damning indictment of the education system.   Over the years, however, I have realized that the story has a more positive connotation. Short-term connections have only transient effects, but long-term connections do not happen automatically – it requires energy, passion, resourcefulness, and strategy. All good things to have for any graduate student. 

On Coincidence  and Cross-Disciplinary Research .... 

The  professor who teaches immediately after me often waits patiently  outside the door as I wrap up my lecture.  When the class ends, I clean the blackboard and pick up my bag. He has already put down a thick book of Enviromental Science on the table, getting ready for the students. Beyond polite smiles, we do not have time for an introduction.  

On the last day of the semester, there is a lunch  to celebrate the service anniversary of the faculty members, I recongize him across the room. The annoucer says that he is  being honored for his 50-years of teaching.  After lunch,  I congratulate him and introduce myself as an Electrical Engineer.   His face brightens immediately as he tells me of his decades-long hobby of restoring old-vacuum tube radios, some dating back to 1930s. I am mesmarized as he talks about  heterodyning, level-shifters, intricacies of AM and FM bands, the detective work one needs to find the circuit diagram, and the Florida store he orders the tubes from.  His love for the subject, his passion, his knowledge sparkle.  I spent the whole semester as a temporal-neighbor without knowing how interesting a person he is, but  I now have a world-class mentor in analog electronics, who just happens to be a professor of civil engineering!  

Keywords: Observations

On Rereading Feynmann's "There is Plenty of Room at the Bottom"

The tone is amazing. The breadth is amazing: making, reading, and writing.  Invitation for facial recognition. Scaling ideas. Common facts. Technology details. 

Thinking about multi-functional devices ... 

A transistor amplifies, a solar cell transforms sunlight to electricity, a sensor senses analytes, and a battery provides storage.   We learn in school that the devices were developed with  a specific goal is mind and our job as engineers  is optimize core functionality of the device for the specific role it needs to play in a circuit or system.   This rigid single-device single-function paradigm is beginning to change.  After all, the traditional model  is akin to saying that simply because   a painter paints, a novelist write, and a professor teaches, they cannot or do not do anything else! I am beginning to see that reports of a solar cell using own output as the brightness sensor of the sky to orient itself to maximize output, a fuel-cell glucose sensor obviating  the battery  by using the energy of the reaction itself, the wires carrying the current to the transistors also serving as its personal  temperature-sensor,  a single-transistor serving as multi-color photo-detectors,  and a camera  charging  its own battery by working part-time as a solar cell part-time. What are the fundamental limits of these multi-use components and what are  the trade-off among efficiency, detection-limit, and sampling rate of these multi-use autonomous syspritems? These are fundamental questions for the era of self-sustaining and self-calibrating electronic devices needed for smart-health, smart-agricuture, and smart-everything systems. 

Keywords: Observations

A Time to grow and a time to pause ... 

African turquoise killfish uses diapause to extend it lifetime by 2 or 3.  When challenged by starvation or overcrowding, C. Elegans can lie dormant for 10-20 normal generations untoched by the passage of time to emerge better prepared to resume the normal function.  In fact, the lifetime can be extended, as if the period of pause has self-healed any damage done.  A related idea involves storing information in DNA of tough microbes, such as Halobacterium salinarum -- a hard to kill, salt-tolerant microbes that has 25 backup copies of each chromogome and can pack 300 MB of data per nucleus. You cannot kill them with poison, vacuum, radiation! And one can wake them up from hybernation after millions of years.  It does have a cryptonite, however!  Freshwater does it in.  

AgriPhotovoltaics: https://thecounter.org/agrivoltaics-farmland-solar-panels-clean-energy-crops/

Teaching electronics in a different way 

Youtube has varied content, to say the least! Yet,  youtube do provide content with deep insights that can transform how one thinks about "well-understood" issues. 

A recent debate about the correctness of the Kirchoff's law ...

https://www.youtube.com/watch?v=eqjl-qRy71w

https://www.youtube.com/watch?v=LzT_YZ0xCFY

https://www.youtube.com/watch?v=LGdN7rDB3XE

Kathy Loves on Physics and History ...

History of Ohm's law:  https://www.youtube.com/watch?v=fk_BpXlfZ8U

Wheatstone Bridge: https://www.youtube.com/watch?v=yCURsJoXHfs

On hype and doing science the right way

At Purdue, I have a good fortune to work with deeply thoughtful colleagues.  Among them, I enjoy reading Prof. Kinam Park's blog on that takes a long view of things. 

Data-Centric AI ... A new paradigm

• Holmes to Watson: It is a capital mistake to theorize before one has data. Insensibly one begins to twist fact to fit theories, instead of theories to suit facts." (Mastermind by Maria Konnikova) 

• "50 is better than 10000," Andrew Ng, Unbiggen AI. 

• Prof Alam (at 42:00) https://www.youtube.com/watch?v=x6cTLjUc5YA

• Prof Roy (at 48:00) https://www.youtube.com/watch?v=hsTSFOLrO2c&t=18587s

Giants come in all sizes 

Hermann Gummel (Sept. 5 at 99) and  James Lovelock (July 26th, 2022 at 103). One on the Gaia hypothesis and the other on a numerical technique called S-G techniques in an appendix of paper.

Reflections on CHIPS act

A NY Times article explains the challenge of the middle class. Can the jobs return? Without existential threat, can the elites change?  https://archive.nytimes.com/www.nytimes.com/interactive/2012/01/20/business/the-iphone-economy.html

A NYtimes articles on the CHIPS act: https://www.nytimes.com/2023/01/01/technology/us-chip-making-china-invest.html 

The new chip factories would take years to build and might not be able to offer the industry’s most advanced manufacturing technology when they begin operations. Companies could also delay or cancel the projects if they aren’t awarded sufficient subsidies by the White House. And a severe shortage in skills may undercut the boom, as the complex factories need many more engineers than the number of students who are graduating from U.S. colleges and universities.

Two books  

A PhD is not enough: A Guide to Survival in Science"  by Peter J. Feibelman (Sandia Distinguished Scientist). The Internet is not what you think it is: A History, A Philosophy, and a Warning"   Fragmentation of attention. Network existed all along.  Joseph Marie Jacquard's automated loom, capable of transferring a design onto silk that had been programmed into a sequence of punched cards. punched-card loom of 1808 provides a synthesis of https://www.youtube.com/watch?v=K6NgMNvK52A  https://www.youtube.com/watch?v=x_ijmjx7Xys 

David McCullough's book "The Pioneers" introduced me to the amazing history of the creation of the Northwest Territory, which would eventually become Ohio, Indiana, Illinois, Michigan, and Minnesota.  The 1783 Treaty at Paris recognized America's claim to these regions. The Ohio Company sent pioneers from New England to the Northwest Territory.  David tells the origin story through the work of Manasseh Cutler, a polymath (Yale graduate, politician, member of the American Association of Arts and Sciences, among many other things) had the purchase ratified by Congress in 1787, and concluded as the death of Samuel Hildreth, another polymath (doctor, geologist, painter, author), in 1863.  The story of the first settlement in Marrieta, Ohio,  is inspiring and the conflict with the Native Americans difficult to read. 

Addictive Reliability:  https://www.youtube.com/@mryeester 

chatGPT writes about the reliability of wearable biosensors!

Wearable biosensors are devices worn on the body that can measure biological data, such as heart rate, body temperature, and physical activity. They can be used for a variety of applications, including fitness tracking, medical monitoring, and disease management. Wearable biosensors can be integrated into clothing, jewelry, or even temporary tattoos, and can connect to smartphones or other devices to transmit data. Advancements in technology have led to the development of more sophisticated biosensors, such as those that can measure glucose levels for diabetes management. However, there is still ongoing research to improve the accuracy and reliability of these devices.

The reliability of wearable biosensors refers to their ability to consistently and accurately measure biological data. The accuracy of wearable biosensors can be influenced by various factors such as the type of sensor used, the location of the sensor on the body, and the environment in which the sensor is used. For example, some wearable biosensors may have a hard time measuring heart rate or oxygen levels in people with darker skin tones. Additionally, sensors can be affected by external factors such as movement, temperature, and humidity.

Research has shown that the reliability of wearable biosensors can vary widely, and many devices have been found to have relatively low levels of accuracy. Studies have found that some wearable biosensors can have large discrepancies between the data they collect and the actual biological data. One of the most common issues with wearable biosensors is that they often require calibration, which can be difficult to perform accurately and frequently.

To improve the reliability of wearable biosensors, researchers are developing new technologies and algorithms that can help to increase the accuracy and consistency of the data collected by these devices. There is ongoing research to improve the sensors themselves and to develop methods for correcting errors in the data they collect. Additionally, wearable biosensors are increasingly being tested in clinical settings to validate their accuracy and reliability.

Overall, the reliability of wearable biosensors is still an active area of research and development, and more work is needed to ensure that these devices can provide accurate and consistent data for various applications.

I could not have written it better! 

Purdue Resources

• Templates for Marketing and Communication: https://marcom.purdue.edu/

• Semiconductors at Purdue: https://engineering.purdue.edu/semiconductors 

What I learned from Responsible Conduct of Research Training

• Must acknowledge results that arose from formal and informal discussions at any setting

• Courtesy authorship, ghost authorship, etc. are deceptive and should be avoided. If you want to include someone, make sure the person makes a "significant intellectual  contribution."  Also, do not try to increase the publication  count by  "least publishable unit" publishing or "duplicate publishing." 

• The head of the research group, the person responsible for the overall project,  is typically listed last. 

• Multi-disciplinary research involves parallel research within disciplinary boundaries that are joined together at the end of the project; interdisciplinary research implies working together on a common problem from their respective disciplinary perspective; finally, transdisciplinary research refers to an even more collaborative form of work, where researchers approach a common from an integrated conceptual framework. 

• Conflict of interest can be institutional, moral, financial, and so on. It must be disclosed and officially managed.   

• Research misconduct is defined as fabrication, falsification, or plagiarism in proposing, performing, and reviewing results, or in reporting research results. 

• https://www.citiprogram.org/verify/?k1dd22cca-c1ad-4cb8-bae6-b6164dddf33c-28677350

• https://www.citiprogram.org/verify/?w4b321d14-41c8-4b97-8136-f8b55e563d09-28677350

Suggestions about writing the  Ph.D. Thesis 

1. Use the overleaf latex to write the thesis. 

2. Use a single ppt file for the figures. If, on average, there are 12 figures per chapter, then use slides 1-15 for Chapter 1, 16-30 for Chapter 2, etc. Keep the unused slides empty. Print the ppt into high-quality pdf, then use crop-pdf software to eliminate white spaces. 

3. Figure fonts should be Cambria.  Keep all the lines black, and consistently use just a few colors, e.g. black, magenta, Turquoise. 

4. The data for all the figures should be included in the Excel file. Use 1 sheet for each chapter.  Use the columns title to indicate Fig. 1,  Fig. 2, etc. 

5. Upload the ppt, pdf, and Excel files in the overleaf "Figures" folder. 

6. In the main file, use this helpful set of packages. Write the SI units using \SI{number}{unit} command. Use $ A\tsub{B}$ to write the subscripts.  And use \ce{H2O} to write all chemical equations. 

%%%%%%%%%%%%%

%  https://www.overleaf.com/latex/templates/purduethesis-template-for-purdue-university-theses-dissertations-etc/yttwrmtjyskn

\documentclass{PurdueThesis}

%  ======================================

%  Package for figures and circuit diagrams

%  ===========================================

% graphicx tutorial: https://latex-tutorial.com/?s=graphicx

\usepackage{graphicx}

%\usepackage{w-bookps_mod}

 \usepackage{caption}

\DeclareGraphicsExtensions{.pdf,.jpeg,.png,.jpg,.eps}

\usepackage{subcaption}

\usepackage[caption=false,font=footnotesize,subrefformat=parens,labelformat=parens]{subfig}

\pdfminorversion=7

% https://www.latex-tutorial.com/tutorials/circuitikz/

\usepackage{tikz}

\usepackage[siunitx]{circuitikz}

% Excellent circuit diagram maker: https://app.diagrams.net/  and https://www.youtube.com/watch?v=WRTELZP1l0Y  https://www.youtube.com/watch?v=uQDgtME-7DQ

% \usepackage[pgfplots]  https://www.youtube.com/watch?v=5jmIHOWpEg0 

% =================================== %

% Packages for Tables

% =================================== %

\usepackage{multirow}

\usepackage{booktabs}

\usepackage{threeparttable}

\usepackage{amsmath}

\usepackage{amsfonts}

\usepackage{amssymb}

\usepackage{diffcoeff}

\newcommand{\tsub}[1]{_{\mathrm{#1}}}

\newcommand{\tsup}[1]{^{\mathrm{#1}}}

\usepackage{mathtools}

\usepackage{multicol}

% =================================== %

% S.I. units system

% =================================== %

\usepackage{textcomp}

\usepackage{siunitx}

\sisetup{detect-weight = true} % to have the text style similar to surrounding

% =================================== %

% Appendix in the ToC

% =================================== %

\usepackage[titletoc]{appendix}

% =================================== %

% Abbreviations and Symbols

% =================================== %

\usepackage[acronym,nopostdot,shortcuts]{glossaries}

\makeindex

\usepackage{color,soul}

% Red Color and Green color

\DeclareRobustCommand{\hlred}[1]{{\sethlcolor{red}\hl{#1}}}

\DeclareRobustCommand{\hlgreen}[1]{{\sethlcolor{green}\hl{#1}}}

\usepackage{hyperref}

\hypersetup{

  colorlinks   = true, %Colours links instead of ugly boxes

  urlcolor     = magenta, %Colour for external hyperlinks

  linkcolor    = blue, %Colour of internal links

  citecolor     = red %Colour of citations

}

\urlstyle{same}

% ====================================================== 

% % subfigure reference ...

% Let us consider the simple system shown in \cref{fig_ch_2:buckling_stick}\subref{fig_ch_2:buckling_stick_a} constituted o 

%     % =================================== %

% \begin{figure}[t]

% \centering{

% \includegraphics[page=2]{figures/Landau_Electronics_Book_Figures_Cropped.pdf}

% \subfloat{\label{fig_ch_2:buckling_stick_a}}

% \subfloat{\label{fig_ch_2:buckling_stick_b}}               

% \subfloat{\label{fig_ch_2:buckling_stick_c}}    

% }

% \caption{\protect\subref{fig_ch_2:buckling_stick_a} Stick of total length $2L$ at rest. \protect\subref{fig_ch_2:buckling_stick_b} Situation with small pressure $F\tsub{P}$ applied from both sides of the stick. \protect\subref{fig_ch_2:buckling_stick_c} When the applied pressure exceeds a certain critical value $F\tsub{P,C}$ the stick buckles and becomes unstable.}

% \label{fig_ch_2:buckling_stick}

% \end{figure}

% % 

\setcounter{secnumdepth}{3}

\setcounter{tocdepth}{2}

\newcommand{\VT}[1]{\ensuremath{{V_{T#1}}}}

%% use a box to expand the macro before we put it into the section head:

\newbox\sectsavebox

\setbox\sectsavebox=\hbox{\boldmath\VT{xyz}}

\usepackage{import}

\usepackage{ifthen}

\usepackage{soul}

\usepackage{xcolor}

% =================================== %

% Package for Homework Boxing 

% =================================== %

\usepackage[most]{tcolorbox}

\newcounter{homework}[chapter]

\renewcommand{\thehomework}{\thechapter.\arabic{homework}}

\newcommand{\homework}[2][]

{ \refstepcounter{homework}

{ \vspace{.5\baselineskip} \noindent \hspace{0.01\textwidth}

% \fbox{

\begin{tcolorbox}[width=0.98\textwidth,breakable,

                 boxsep=0pt,   left=5pt,   right=5pt,   top=4pt,  arc=0pt,    boxrule=1pt,toprule=1pt,   % colback=white

                 ]

\vspace{.5\baselineskip}

{\bf Homework~\arabic{chapter}.\arabic{homework}: #1

\vspace{.5\baselineskip}\\}

#2

\vspace{.5\baselineskip}

\end{tcolorbox}

\vspace{.5\baselineskip}

}}

% =================================== %

% Package for comments and chemical formula

% =================================== %

\usepackage{verbatim}

\usepackage[version=4,arrows=pgf-filled,

textfontname=sffamily,

mathfontname=mathsf]{mhchem}

\usepackage[sectionbib,numbers]{natbib}

\usepackage{bibunits}

\defaultbibliography{Zotero}

\renewcommand{\bibname}{References}

%\usepackage{hyperref}

\usepackage[capitalise]{cleveref}

%\RequirePackage[capitalise,<option2>,...]{cleveref} 

\begin{document}

\newcommand{\subs}[2] {#1_\mathrm{#2}}