Category Archives: model

Blood Moon Representation



I got up this morning very early. My goal was to see the lunar eclipse, which in Plano, Texas, occurred between 5:25 and 5:35AM CST today (October 8, 2014). A total eclipse is often called a blood moon. The Incans and Mayans had a wonderful story where the jaguar would eat the moon. Hence the reddish color. The sky was very clear up until 5:30 when a few clouds obscured the viewing. A lunar eclipse is when the earth is between the moon and the sun. Just prior to the eclipse, there was a sliver of white from the sun on the right side (toward the West). But then, the eclipse happened, and it was very impressive. I tried capturing it with my iPhone. Nothing worked correctly. I kept getting pop-up messages about the phone wanting to access my photos, and then I must have pressed the "selfie" mode by mistake and I was taking pictures of myself.  I couldn't see the phone (forgot the reading glasses). After a while, I put down the technology and just spent my time experiencing. The lesson here is that, at the core, it is our personal experience that precedes any art or science that we may do with the world. We can re-create our experience, thus creating something we call art so we can share our experience with others. Or we can observe and find patterns: science. Just before I headed back home, I kept on hearing a song in my head that would not go away: "And if your head explodes with dark forebodings too. I'll see you on the dark side of the moon."  Pink Floyd. And then it occurred to me that we were all, for an instant, on the dark side.

Sensing Simulation Models


When I teach modeling and simulation, I tend to focus mostly on the structure of models. I start with a thorough discussion of time and systems concepts, and then move on to cover different sorts of dynamic models in both discrete and continuous space. In the past, I had relied on using examples purely from the real world in emphasizing the importance of modeling. For example, all fast food restaurants, manufacturing lines, and theme parks have one thing in common: queuing networks. A queuing network is a dynamic model abstraction of what happens in these things: objects (often people) wait in line, get served, and move on.  In teaching queuing, and other, models, I am trying something new this Fall. I am starting with human-interaction and media being the means by which to get students interested in modeling. For example, the single server queue (SSQ) shown above has an operation that can be both seen and heard. This one is programmed in Max/Msp (which is a visual language with strong roots in music, imagery, and video). The SSQ is experienced, by tying events to an audio synthesizer. Everything is in software. An SSQ becomes an audiovisual instrument.


Bipolar Thinking


Bipolar thinking could mean many things, but I refer to it as thinking with two poles, connecting art and science. let's call the poles the north and south poles since the earth can be used as a metaphor. At the north pole, we put down a flag labeled "mental concept." The art of abstraction, as with mathematical thinking, is to dwell near the north pole. At the north pole, representations involving the senses do not exist. One must walk in the direction of the south pole, which means in any direction, for more sensory experience. The term "abstract" is used in art as well, however, art relates to the senses and for pure abstraction found in mathematics, there is only thought. At the south pole, we have pure experience. Let me give an example from mathematics: the circle. We learn in mathematics that the circle is a concept, an idea and that anything you hear, touch, or see is not a circle-- it is a representation of the circle concept. This means that things drawn on paper, spoken, or writing the word "circle" are not circles. Where do you position yourself on the earth: do you inhabit the poles, or are you somewhere near the equator? Maybe you live in Iceland or Borneo? My suggestion is that we should be constantly walking between two poles without being overly attracted to either one. Every time I see an object that reminds me of a circle, I celebrate the uniqueness of that object, taking time to experience it. But then, I am drawn to the wonderful reduction, abstraction, and concept of circle--all of the experienced objects are identical near the north pole. This bipolar thinking is common at the lab because we are creating representations of math and computing concepts. Thankfully, we do not actually have to pack our snowshoes.

Preserve the Model


Van Gogh produced compelling artwork ahead of his time. This one is called "Wheat field with cypresses" from 1889. The original is in the National Gallery in London. How do we archive this kind of work? Clearly, digital scans of all varieties and wavelengths can be employed to record the static painting. But that is the final product. No art is static. It is all dynamic, time-based media, to use a phrase coined within media studies. The only reason why we think of Van Gogh's artistry as static is that there is no recorded process of how it was created over time. Contrast this situation against the products of modern cinema and video games.  These products are the result of complex models of geometry and dynamics. So, if you want to archive a video game, best to archive the process, the shape, and the behaviors. Preserve the simulation models rather than an end-product.  How something changes over time is precious and ultimately more valuable than what emerges from the end of a creative pipeline. Even with packages such as Photoshop or Gimp, there is a process that is stored as a dynamic stack of human interaction events. That is what we ought to be saving wherever possible. The focus on process, and on model, can also have an effect on how we think of art-not only from the perspective of archiving. Musicians and performers are used to modeling. Maybe, the rest of us should jump on board.

Computing as Science


My last post referred to the TEDx talk given a few weeks ago at the University of Texas at Dallas. The subject was "Computing Everywhere." This talk was based on a paper I wrote for the 2014 ACM SIGSIM-PADS conference recently held in Denver. The paper entitled "Computing as Model-Based Empirical Science" can now be found in the ACM Digital Library. To see computing everywhere, or to see it as a science like physics or biology, the first step is to distinguish "computing" from "computer." Computing is based on information structures and processes. Computers use whatever technologies are available (since the 1940s, electricity and electronics) to facilitate computing. The argument for the Universe as a Computer, under the name Digital Physics, is a related hypothesis although at a finer level of granularity.

Design for a Model


The above design is from William Lawson's "A New Orchard and Garden" which was published in 1618, and available from Project Gutenberg. Note the hexagonal tree configuration labeled B. Design is with us everywhere from Lawson's garden to the physical feel and visual layout of your phone. Design is also central to the task of modeling. I was recently reading Chris Conley's Leveraging Design's Core Competencies, and was struck by the importance of three concepts: #2: the ability to work at a level of abstraction appropriate to the situation at hand, #3: the ability to model and visualize solutions even with imperfect information, and #7: the ability to use form to embody ideas and to communicate their value. These concepts are central to modeling as employed within STEM (Science, Technology, Engineering, and Mathematics).  In Computer Science, we employ models for many tasks. These models are designs for artificial languages. Send this information through node X, and split the result across nodes Y and Z. Plant the apple tree at node A, which is fed from stream B.

The Humanities Affect


I was fortunate over the past three weeks to have presented at, and collaborated with, two excellent universities: The University of Kansas (KU) and Southern Methodist University (SMU). I gave invited talks at each. At KU, the talk was inside of their Institute for Digital Research in the Humanities (IDRH), and at SMU, their Computer Science Colloquium.  The talk was the same at KU and SMU, and centered on the notion that the arts and humanities can affect computing in deep ways. To consider this new set of connections, we must go beyond thinking of computing only as a technology. Stretching ourselves in this fashion is natural for mathematicians and computer scientists, but not so much for everyone else. We also need to divorce computing from technology in how we see the world. The world is full of computing if we define computing as the study of information dynamics. A video (or click on the photo of Nefertiti above) was recorded and rendered at IDRH at KU. Can we get beyond thinking of computing as something that occurs inside of boxes? If we can, then computing becomes even more embedded in culture.


Making the Abstract Concrete


During Engineering Week at the end of February, the Creative Automata Lab hosted an onslaught of visitors of all ages. We showed several projects representing the Lotka-Volterra predator-prey relationship, a mechanical integrator using simulated sand, and the use of force feedback in embodied interactions with the distributive law of algebra. A video was produced from the projects, and students are interviewed for their perspectives. The video can be seen by using this link or by clicking on the photo of the ATEC Building shown above.

Models of Addition



Isn't addition like this: 1 + 2 = 3 ? If your technology is a typewriter, it is. This is certainly true for this blog since my human-machine interface is quite limited. And that is an interesting aspect of modeling: all models are tied to the technologies used to design and create them. So, if you have a marble quarry, then all of your models will look like stone. And if you use a typewriter or, equivalently, the modern keyboard, then your models will look like Arial, Helvetica, Times Roman, or whatever font family you happen to employ. For Szücs (Similitude and Modeling, 1980), the above mechanical components are models of addition. It is a way of thinking about mathematics using the technologies required to make gears and pulleys. There is nothing magical about typography in mathematics--it is just cheap and therefore useful for communication and standardization. Something that is not immediately apparent, but important, is that the models of addition contain the parameter of time. The addition using standard notation for simple addition is S(t) = a(t) + b(t).

Engineering Week


Our Creative Automata Lab had its open house during the Engineering Week celebrations on Saturday, February 22nd (yesterday between 10am and 2pm CST in Dallas). The turnout was phenomenal. I have to thank the organizers of the week-long event and to all of my students who created amazing demonstrations for everyone. What are the summary points? People like to touch things, play with them, and understand fairly complex mathematical and computing phenomena by experiencing them firsthand; hearing, seeing, and interacting. Writing on the whiteboard doesn't cut it any more. The two 3D printers (Maker Bots) in the lab were exciting for visitors not so much because 3d printing is a new phenomenon, but because these printers have visible moving parts. You can see what is happening because the printers  are designed to show their internal components, a bit like the Centre Georges Pompidou in Paris. We'll be sorting out lessons-learned from the event for some time to come. Next up will be blog posts on our exhibits and the video that was compiled based on student thoughts and the lab mission.


Steampunk Automata


There is something interesting about the Steampunk movement. Steampunk takes inspiration from the past to reinvent the future. I am reminded of the fictional worlds created by H. G. Wells and Jules Verne. The above image is from Indulgy and is an example of Steampunk and fashion. There are subtle connections to 19th century engineering where scientists such as Maxwell and Kelvin did modeling of mathematics that was touchable, where cause and effect were clear and visible. We see the raw elements of computing (e.g., information flows) everywhere we look and yet it is with classic machines from the past that we find information-rich experiences as indicated in Organum Hydraulicum. Steampunk, and its inroads into theatre, fiction, and fashion may be partially a result of our deep human need to touch, see, and hear information. To model, Steampunk style.


Inter-Species Dynamics


The Lotka-Volterra model representation challenge was discussed earlier as a goal for our lab in preparation for Engineering Week, culminating in a set of demonstrations to be given on February 22, 2014. The image shown is a partial screen shot of a simulation created by Karen Doore, a PhD student in Computer Science, also working in the Creative Automata Lab. The time-based dynamics of predator-prey are seen on the right hand side and may look familiar to most modelers of ecological systems where predators and prey interact, causing the population levels to oscillate. The diagram on the left differs from the representational norm--it is an interactive Javascript sketch of an analog water computer. The water computer stems from an underlying modeling language formalism called System Dynamics. Water levels depict the predator and prey populations rising and falling. Input and output valve settings are a function of population levels sensed with water floats. The equations are also represented in a way that the coefficients change inside the equation text, but not shown in this figure due to lack of space. Here are the implemented equations:

\frac{dP}{dt} = -Pm + bHP ; \frac{dH}{dt} = Hr - aHP