Wolfram Blog http://blog.wolfram.com News, views, & ideas from the front lines at Wolfram Research Mon, 27 Oct 2014 18:25:33 +0000 en hourly 1 http://wordpress.org/?v=3.2.1 Calling All Goblins: Tweet-a-Program Halloween Code Challenge http://blog.wolfram.com/2014/10/27/calling-all-goblins-tweet-a-program-halloween-code-challenge/ http://blog.wolfram.com/2014/10/27/calling-all-goblins-tweet-a-program-halloween-code-challenge/#comments Mon, 27 Oct 2014 18:25:33 +0000 Wolfram Blog http://blog.internal.wolfram.com/?p=22220 Halloween is quickly approaching, and to help you gear up for trick-or-treating, costume parties, and pumpkin carving, we’re issuing another Tweet-a-Program Code Challenge! This time, instead of spaceships and planets, we want you to tweet us your spookiest Halloween-themed lines of Wolfram Language code. We’ll then use the Wolfram Language to randomly select three winning tweets (and a few of our favorites) to pin, retweet, and share with our followers. Winners will also be awarded a free Wolfram T-shirt!

Take some inspiration from these examples, while you come up with your creepy codes:

Tweet-a-Program skull

Tweet-a-Program Halloween

In order to win, your Halloween-themed submissions must be tweeted to us before the clock strikes midnight, Pacific time, on All Hallows’ Eve (11:59pm PDT, Friday, October 31). So you don’t waste needed code space, no hashtag is required with your original submission, but we encourage you to share your results by retweeting them with hashtag #SpookyCode.

We’re excited about the possibilities—just keep an eye on your creation and make sure that it doesn’t… come alive!

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Wolfram Data Summit 2014 http://blog.wolfram.com/2014/10/22/wolfram-data-summit-2014/ http://blog.wolfram.com/2014/10/22/wolfram-data-summit-2014/#comments Wed, 22 Oct 2014 16:01:05 +0000 Wolfram Blog http://blog.internal.wolfram.com/?p=22182 This year’s Wolfram Data Summit brought together innovators in data science, creators of connected devices, and leaders of major data repositories for two days of high-level discussion about challenges and opportunities facing the worldwide data community.

This annual Summit offers an exclusive group of thought leaders an opportunity to meet and share insights into new and ongoing projects. But in light of the high caliber and exceptionally broad interest of this year’s presentations—and for the first time ever—we are sharing videos of the Summit presentations with the public, including the keynote from Stephen Wolfram, CEO of Wolfram Research and creator of Wolfram|Alpha.

For more information on next year’s event or to apply for an invitation, please visit the Wolfram Data Summit website!

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Martin Gardner’s 100th Birthday http://blog.wolfram.com/2014/10/21/martin-gardners-100th-birthday/ http://blog.wolfram.com/2014/10/21/martin-gardners-100th-birthday/#comments Tue, 21 Oct 2014 14:56:35 +0000 Ed Pegg Jr http://blog.internal.wolfram.com/?p=21475 For today’s magic show:
A century ago,
Martin Gardner was born in Oklahoma.
He philosophized for his diploma.
He wrote on Hex and Tic-Tac-Toe.
The Icosian game and polyomino.
Flexagons from paper trim,
Samuel Loyd, the game of Nim.
Digital roots and Soma stairs,
mazes, logic, magic squares.
Squaring squares, the golden Phi.
Solved the spider and the fly.
Packing circles (with corrections),
ellipses, pi, and conic sections. Martin GardnerPenrose Tilings and Wieringa Roofs
Tiling with PentominosHamiltonian Tours on Polyhedra


Group theory braids and primal gaps,
Latin squares, the four-color maps.
Hypercubes and Turing machines,
curves of constant width, eight queens.
The Klein bottle when cut in halfs,
helices and Graceful Graphs.
The Arecibo message, divisibility tests.
The Ulam spiral, parity checks.
Bracing buildings that won’t tilt,
trisections, Mrs. Perkins’s Quilt.
Pascal’s triangle, ternary scoring,
bouncing balls for water pouring.
Constrained geometry construction,
e and patterns of induction.
The abacus and random walks,
cyclic numbers, sliding blocks.
Pythagorean theorem, gears,
art of M. C. Escher, spheres.
Dominoes and overhang jutting,
infinite series, fair cake cutting.
Aleph-Null and Aleph-One.
For Game of Life, a glider gun.
Paterson’s worms and knotted torus,
paper folding, Nine Men’s Morris.
A problem solved by Andrew Wiles.
Pigeonholes and Penrose tiles.
Peg solitaire, a loop of string,
folded dragon curves, I Ching.
Rep-tiles and Borromean rings.
The pentagons of Marjorie Rice,
shuffling, “The Kiss Precise,”
tetrahedra, cycloids, dice.
Diophantine analyses,
geometric fallacies.
Dice nontransitivity,
special relativity.
The list meanders on for days,
but that’s enough to give him praise.
The Circles of DescartesGolden Spiral
Mazes on Various Surfaces
Dandelin Spheres for an EllipseMondrian Four Coloring
Magic Squares and DesignsOverhanging Cards
Graceful GraphicsKnot Explorer
Bicycle Wheels Using Curves of Constant Width
Random Chord Paradox
Ammann ChairCurry Triangle ParadoxLooney Gears
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Summer has drawn to a close, and so too have our annual internships. Each year Wolfram welcomes a new group of interns to work on an exciting array of projects ranging all the way from Bell polynomials to food science. It was a season for learning, growth, and making strides across disciplinary and academic divides. The Wolfram interns are an invaluable part of our team, and they couldn’t wait to tell us all about their time here. Here are just a few examples of the work that was done.

2014 summer interns

Paco Jain

Paco Jain
Wolfram|Alpha Scientific Content,
Wolfram|Alpha
“This summer, I worked on adding scientific content to the physical systems domain in Wolfram|Alpha. While there is a lot to learn, everyone I worked with seemed enthusiastic to help me get up to speed, and I was able to form several valuable mentoring relationships. I also felt that I was given the resources and responsibility I needed to allow me to make meaningful contributions to the Wolfram|Alpha product. The experience has me already thinking about pursuing a full-time position at Wolfram!” As of October 2014, Paco is employed at Wolfram Research full time.
Daniel McDonald

Daniel McDonald
Wolfram|Alpha Scientific Content,
Bell Polynomials and Recursive Algorithms
“This summer at Wolfram|Alpha I worked as the Special Functions Intern. My primary project was reading mathematical literature in order to extract and verify formulas that could be useful for The Wolfram Functions Site as well as for possible Mathematica implementation. The most interesting part of my work involved creating a compendium of information about Mathematica‘s BellY function that computes various types of Bell polynomials, which are used in Faà di Bruno’s formula for computing arbitrary derivatives of the composition f(g) (as well as in generalizations of this formula for computing arbitrary derivatives of compositions of arbitrary depth). I devised an original functional recurrence that suggested a quick recursive algorithm for computing generalized Bell polynomials; as this algorithm ran much faster than Mathematica‘s at the time, it was implemented into Mathematica 10.0.1. This recurrence and thus the algorithm (with different base cases) can be applied in a more general environment, and I am currently drafting a paper to submit to an algorithms journal.”
Mark Peterson

Mark Peterson
Scientific Information Group,
Wolfram Demonstrations Project
“During my internship in the Scientific Information Group at Wolfram Research, my work has primarily been centered on the Wolfram Demonstrations Project. Essentially, Demonstrations are self-contained programs written in the Wolfram Language that are designed to appeal to the user in a highly intuitive and interactive way. Whether working on the Project directly or on alternate applications for its material, my time has been spent developing this sort of content.”
Visualizing the Thomson Problem
Jake Wood

Jake Wood
Mathematica Algorithms R&D,
Mathematica GeoGraphics
“Joining the Wolfram team earlier this summer was an exciting professional milestone for me. I am a big fan of not only the software that has come from Wolfram, but also the mission and ambition to proliferate and nurture big ideas. My patient mentor explained that I was to figure out how to make the generated maps in GeoGraphics (new in Mathematica 10) move around and update from mouse clicking and dragging. Additionally, the maps needed to be zoomable, similar to maps online used for navigation. Right now my prototypes deal with the maps themselves instead of the verbose layers of graphics data that Mathematica is capable of imbuing. In the future, though, who knows. Getting the panning and zooming to work proved a difficult task; however, the brunt of the summer was spent on improving the performance speed. No one wants to use an interactive map that is insufferably unresponsive. The utility of this application is pretty clear, as it is similar to programs that people already use daily.”

Jessica Zhang

Jessica Zhang
User Experience,
WolframTones
“People would think as a User Experience Designer I would only be designing detailed features within a product or workflow. However, at Wolfram, I not only got to do those things, I also got to take part in the bigger decision-making design processes, even as an intern. I was given the opportunity to learn a variety of skills that are important and also at the cutting edge of the field. Technical skills include wireframing, wireflowing, diagramming, and interface design. Oh, and also using the espresso machine!”

Andrew Blanchard

Andrew Blanchard
Wolfram|Alpha Scientific Content,
Named Physical Effects
“For my internship with Wolfram Alpha, I assembled a list of named physical effects. A typical effect provides a link between measurable physical quantities, which are already incorporated into Wolfram|Alpha. Thus, making information about known physical effects computable enables the exploration of relationships between measurable quantities. In addition, the searchable data provides a window into the relationship between the discovery of new effects and advances in the field of physics. By making scientific information searchable, Wolfram|Alpha is providing a wonderful service for researchers, students, and anyone curious about exploring science.”
Surojit Ganguli


Surojit Ganguli
Wolfram|Alpha Socioeconomic Content,
Computational Capabilities
“I was part of the team that was involved in increasing the computational capabilities of Wolfram|Alpha in the domain of vehicle dynamics. As a Computational Science and Engineering Minor at UIUC, the opportunity to explore the various ways in which computations are being performed at Wolfram was in itself a rewarding experience. As an additional bonus, I definitely improved in the area of functional programming by using Mathematica.”

Ying Qin

Ying Qin
Wolfram|Alpha Scientific Content,
Food Data
“I’ve been working on expanding food-related information in the Wolfram Knowledgebase. Among other things, this included the characterization and classification of food; I did research involving USDA data and other data sources. I was also working on expanding the food glossary, which gives a more detailed description of the available content. Furthermore, using my knowledge as a Food Science student, I was able to do things like classify fatty acids into groups. My advice to prospective interns is that you shouldn’t hesitate to apply even though your major is not computer science or engineering. As a Food Science major, I was happy to get involved here, and felt like it was a truly valuable experience.”

 

It’s been an amazing summer all around, and we couldn’t be happier with the contributions our interns have made. While we are sad to see some of them go, we are excited by the new talent that has been added to our team and can’t wait to see what next year will bring!

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Computation Meets Data Science in London, November 21 http://blog.wolfram.com/2014/10/13/computation-meets-data-science-in-london-november-21/ http://blog.wolfram.com/2014/10/13/computation-meets-data-science-in-london-november-21/#comments Mon, 13 Oct 2014 15:07:20 +0000 Conrad Wolfram http://blog.internal.wolfram.com/?p=21694 I’m usually going on about “computation,” or in education, “maths.” But I’ve come to appreciate just how much of computation’s utility in modern life centres around data (rather than, say, algebraic modelling).

Clearly data science is a major, growing, and vital field—one that’s relatively new in its current incarnation. It’s been born and is driven forward by new technology and our ability to collect, store, transmit, and “process” ever larger quantities of data.

But “processing” has often failed to elucidate what’s important in the data. We need answers, not just analytics; we need decisions, not just big data.

Computation in all its forms is a key to getting decisions from data. And funnily enough, it’s not only for analytics that computation’s used, but for enabling human language data interrogation, interactive deployment, and many other examples—crucial usability, not only raw computational power.

It’s to bring all these aspects together that we’re hosting a 1-day summit in London next month entitled “Master Your Data with [the Latest, Most Powerful!] Computation,” that’s with my [ ] editorial.

Master Your Data with Computation: Wolfram Technology Summit

Most people don’t recognise Wolfram as a key data science company. And yet over the last few years, we’ve built up a unique and integrated technology stack not only to offer the most powerful computations on data, but to optimise usability across the whole workflow and, crucially, to be a data science platform. In fact, expect announcements and key showcasing of new tech in London.

Now we have hosted the Wolfram Data Summit in the US for the last 5 years. The emphasis is a little different for our upcoming London summit, though related: “A high-level gathering of innovators in data science, creators of connected devices, and leaders of major data repositories.” In London, we’ll be focused on how new ideas can be deployed today in your organisation.

In the end, London will be a great follow-on, fill-out, and extension to many fields beyond democracy from my TEDx at the UK Parliament kick-off talk earlier this year, in which I addressed the question “Has more data led to better decisions and better democracy?”

Really hope we’ll see you there.

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First Tweet-a-Program Code Challenge: Space Week http://blog.wolfram.com/2014/10/07/first-tweet-a-program-code-challenge-space-week/ http://blog.wolfram.com/2014/10/07/first-tweet-a-program-code-challenge-space-week/#comments Tue, 07 Oct 2014 17:51:59 +0000 Wolfram Blog http://blog.internal.wolfram.com/?p=21584 In honor of World Space Week and this year’s theme of satellite navigation, “Space: Guiding Your Way,” we’re issuing a Tweet-a-Program Code Challenge focused on anything to do with space and getting there. You tweet us your “space-iest” line(s) of Wolfram Language code, and then we’ll use the Wolfram Language to randomly select three winning tweets (plus a few favorites) to shower with retweets, pin or post to our wall, and receive a free Wolfram T-shirt!

Any space-themed submissions tweeted to us @wolframtap all day Thursday and Friday (12am PDT Thursday, October 9 through 11:59pm PDT Friday, October 10) will be eligible to win. To not waste needed code space, no hashtag is required with your original submission, but we encourage you to share your results by retweeting them with hashtag #wsw2014 and #tapspaceweek.

In addition to satellite path tracking and real-time analysis, the Wolfram Language gives you access to all sorts of entities, formulas, and other functionality for astronomical computation and coding—from supernovas, comets, and constellations to the Sun, deep space, and other galaxies.

Maybe you want to remix the planets and their colors, as Stephen Wolfram did in one of his first Tweet-a-Program tweets:

Randomizing planet colors

Or create a 3D mesh visualization of the space shuttle, like @Porco_Mozo:

@Porco_Mozo

Wonder what it looks like to map Mars (or other celestial bodies) in the Bonne projection?

GeoGraphics[GeoModel->=[Mars],GeoProjection->"Bonne"]

Or generate an icon of the current Moon phase?

MoonPhase["Icon"]

Tweet us and see! Regardless of whether you’ve got a meteoric idea or more nebulous intentions, this is truly a stellar opportunity to show off your coding skills.

We can’t wait to see what you create—we’re sure it will be outta this world!

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New Books Based on Wolfram Technologies http://blog.wolfram.com/2014/10/06/new-books-based-on-wolfram-technologies/ http://blog.wolfram.com/2014/10/06/new-books-based-on-wolfram-technologies/#comments Mon, 06 Oct 2014 15:58:35 +0000 Jenna Giuffrida http://blog.internal.wolfram.com/?p=21274 Authors turn to Wolfram technologies to elucidate complex concepts, from physics to finance. Here is a roundup of the latest publications that feature the Wolfram Language and Mathematica.

New books group #1

Particle and Particle Systems Characterization: Small-Angle Scattering (SAS) Applications
by Wilfried Gille

Small-angle scattering (SAS) is the premier technique for the characterization of disordered nanoscale particle ensembles. SAS is produced by the particle as a whole and does not depend in any way on the internal crystal structure of the particle. Since the first applications of x-ray scattering in the 1930s, SAS has developed into a standard method in the field of materials science. SAS is a non-destructive method and can be directly applied for solid and liquid samples.

This book is geared to any scientist who might want to apply SAS to study tightly packed particle ensembles using elements of stochastic geometry. After completing the book, the reader should be able to demonstrate detailed knowledge of the application of SAS for the characterization of physical and chemical materials.

Computer Algebra in Quantum Field Theory: Integration, Summation and Special Functions
by Carsten Schneider and Johannes Blumlein

The book focuses on advanced computer algebra methods and special functions that have striking applications in the context of quantum field theory. It presents the state of the art and new methods for (infinite) multiple sums; multiple integrals, in particular Feynman integrals; and difference and differential equations in the format of survey articles. The presented techniques emerge from interdisciplinary fields: mathematics, computer science, and theoretical physics; the articles are written by mathematicians and physicists with the goal that both groups can learn from the other field, including most recent developments. Besides that, the collection of articles also serves as an up-to-date handbook of available algorithms/software that are commonly used or might be useful in the fields of mathematics, physics, or other sciences.

Mathematics for Physical Science and Engineering
by Frank E. Harris

Mathematics for Physical Science and Engineering is a complete text in mathematics for physical science that includes the use of symbolic computation to illustrate the mathematical concepts and enable the solution of a broader range of practical problems. Due to the increasing importance of symbolic computation and platforms such as Mathematica, the book begins by introducing that topic before delving into its core mathematical topics. Each of those subjects is described in principle and then applied through symbolic computing. The aim of the text is designed to clarify and optimize the efficiency of the student’s acquisition of mathematical understanding and skill and to provide students with a mathematical toolbox that will rapidly become of routine use in a scientific or engineering career.

Multimedia Maths
by Bieke Masselis and Ivo De Pauw

Multimedia Maths provides an accessible guide to understanding and using basic software applications including the golden section, co-ordinate systems, collision detection, vectors, and parameters.

Screen effects and image handling are explained at a complex level using a more detailed outline to build and develop on the basic transformations.

More advanced multimedia themes of quaternion rotation, fractal texture, Bézier curves, and B-splines are deconstructed and usefully linked to an interactive website that includes Mathematica files.

New books group #2

A Math Primer for Engineers
by Colin Walker Cryer

Mathematics and engineering are inevitably interrelated, and this interaction will steadily increase as the use of mathematical modeling grows. Although mathematicians and engineers often misunderstand one another, their basic approach is quite similar, as is the historical development of their respective disciplines. The purpose of this Math Primer is to provide a brief introduction to those parts of mathematics that are, or could be, useful in engineering, especially bioengineering. The aim is to summarize the ideas covered in each subject area without going into exhaustive detail. Formulas and equations have not been avoided, but every effort has been made to keep them simple in the hope of persuading readers that they are not only useful, but also accessible.

The wide range of topics covered includes introductory material such as numbers and sequences, geometry in two and three dimensions, linear algebra, and calculus. Building on these foundations, linear spaces, tensor analysis, and Fourier analysis are introduced. All these concepts are used to solve problems for ordinary and partial differential equations. Illustrative applications are taken from a variety of engineering disciplines, and the choice of a suitable model is considered from the point of view of both the mathematician and the engineer.

This book will be of interest to engineers and bioengineers looking for the mathematical means to help further their work, and it will offer readers a glimpse of many ideas that may spark their interest.

Financial Hacking: Evaluate Risks, Price Derivatives, Structure Trades, and Build Your Intuition Quickly and Easily
by Philip Maymin

This book teaches financial engineering in an innovative way by providing tools and a point of view to quickly and easily solve real, front-office problems. Projects and simulations are not just exercises in this book, but its true backbone. You will not only learn how to do state-of-the-art simulations and build exotic derivatives valuation models, you will also learn how to quickly make reasonable inferences based on incomplete information. This book will give you the expertise to make significant progress in understanding brand new derivatives given only a preliminary term sheet, thus making you valuable to banks, brokerage houses, trading floors, and hedge funds.

Financial Hacking is not about long, detailed mathematical proofs or brief summaries of conventional financial theories; it is about engineering-specific, useable answers to imprecise, but important questions. It is an essential book both for students and for practitioners of financial engineering.

MBAs in finance learn case-method and standard finance mainly by talking. Mathematical finance students learn the elegance and beauty of formulas mainly by manipulating symbols. But financial engineers need to learn how to build useful tools, and the best way to do that is to actually build them in a test environment, with only hypothetical profits or losses at stake; this book gives graduate students and others who are looking to move closer to trading operations the opportunity to do just that.

Introduction to Quantitative Methods for Financial Markets
by Hansjorg Albrecher, Andreas Binder, Volkmar Lautscham, and Philipp Mayer

Swaps, futures, options, structured instruments—a wide range of derivative products is traded in today’s financial markets. Analyzing, pricing, and managing such products often requires fairly sophisticated quantitative tools and methods. This book serves as an introduction to financial mathematics with special emphasis on aspects relevant in practice. In addition to numerous illustrative examples, algorithmic implementations are demonstrated using Mathematica and the software package UnRisk (available for both students and teachers). The content is organized in 15 chapters that can be treated as independent modules.

In particular, the exposition is tailored for classroom use in a bachelor’s or master’s program course, as well as for practitioners who wish to further strengthen their quantitative background.

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The Nobel Prize in Physics http://blog.wolfram.com/2014/10/01/the-nobel-prize-in-physics/ http://blog.wolfram.com/2014/10/01/the-nobel-prize-in-physics/#comments Wed, 01 Oct 2014 15:55:21 +0000 Richard Asher http://blog.internal.wolfram.com/?p=21019 The Nobel Prize in Physics ceremony is upon us once again! With the 2014 winner set to be revealed in Stockholm next week, we at Wolfram got to wondering how many of the past recipients have been Mathematica users.

We found no less than 10 Nobel Prize–winning physicists who personally registered copies of Mathematica. That’s at least one in every eight Physics laureates since 1980! And anecdotal evidence suggests that nearly every Nobel laureate uses Mathematica through their institution’s site license.

Frank Wilczek Wolfgang Ketterle John Forbes Nash, Jr.
Among them are Germany’s Wolfgang Ketterle and American Frank Wilczek. Ketterle was awarded the Nobel Prize in Physics in 2001 for his Bose–Einstein condensation work, and he accepted the award along with fellow physicists Eric Cornell and Carl Wieman. Wilczek, known for his discovery of asymptotic freedom, was selected for the Prize in 2004, along with co-researchers David Gross and Hugh Politzer.

It’s not just in Physics that Mathematica has shone on the Nobel stage. We’ve also had winners in Chemistry and Economics. The case of Economics we’re talking about is none other than famed genius John Forbes Nash. Nash, who was the subject of the film A Beautiful Mind and won the Nobel Memorial Prize in Economic Sciences in 1994, has been among our best-known users.

So rest assured we will be watching all of this month’s 2014 winner announcements with interest…

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Modeling Aircraft Flap System Failure Scenarios with SystemModeler http://blog.wolfram.com/2014/09/29/modeling-aircraft-flap-system-failure-scenarios-with-systemmodeler/ http://blog.wolfram.com/2014/09/29/modeling-aircraft-flap-system-failure-scenarios-with-systemmodeler/#comments Mon, 29 Sep 2014 15:59:01 +0000 Anneli Mossberg http://blog.internal.wolfram.com/?p=21317 Have you heard about the Boeing 747 Dreamlifter that flew to the wrong airport and was forced to land on too short of a runway? Luckily, that story had a happy ending, and no passengers were hurt. Still, it is a potentially dangerous scenario when the landing distance required (LDR) is longer than the runway, and there are other possible reasons for such a situation besides a pilot gone astray.

One potential cause of such a scenario is a flap system failure. Flaps are hinged devices located on the trailing edges of the wings, where their angular position can be adjusted to change the lift properties of the plane. For example, suitably adjusting the flap position can enable the plane to be flown at a lower speed while maintaining its lift, or allow it to be landed with a steeper angle of descent without any increase in speed. One of several resulting advantages is that the LDR becomes shorter. This makes me wonder: Could a small flap failure increase the LDR so much that the assigned runway is suddenly too short?

To answer such a question, you have to understand the effects that a failure on a component level have at a system level. How will the control system react to it? Can we somehow figure out how to detect it during a test procedure? Can we come up with a safety procedure to compensate for it, and what happens if the pilot or maintenance personnel for some reason fail to follow that procedure?

Hydraulics

Together with my colleague, engineer Olle Isaksson, we thought we’d use Wolfram SystemModeler 4 and the newly released Wolfram Hydraulic library to simulate and analyze some potential failures that can occur in the flap system of a Cessna 441 Conquest II aircraft.

Simulating potential failures

The desired angular position of the flaps on this Cessna aircraft is set manually by the pilot via the plane’s instrument panel. Which flap angle is preferable depends, among other factors, on which flight phase the plane is in, since that directly affects which flight characteristics are desired. For example, during takeoff, the flaps are extended to an angle of 10 degrees in order to provide extra lift force, and during landing, they’re extended to 30 degrees to increase both lift and drag force. These seemingly small adjustments to the flaps’ angular position allow for shorter runways, reduce the stress put on the aircraft, and give the pilot more time to react. For this particular aircraft, there are two additional positions: 0 degrees in mid-air and 20 degrees when approaching landing. Take a look at the video below for a short demonstration of how the flaps move.

To watch this video, you must have Adobe Flash Player 10.0 or higher installed and JavaScript enabled. You can download the latest version of Adobe Flash Player here.

The flap system of this Cessna aircraft is electrically operated and hydraulically actuated. This means that the flap system is controlled by electrical signals, but the actual movement of the flaps and landing gears is driven by a hydraulic system with pumps, valves, cylinders, and other useful components. The pilot controls the flap position through a flap selector switch located on the instrument panel. Changing the flap selector switch position sends out an electrical signal that, together with limit switches, energizes a bypass valve so that pressure builds up in the hydraulic power system.

Flap system

In tandem with bypass valve energization, a solenoid of the flap control valve becomes energized, resulting in an open connection between the cylinder (flap actuator) and the pump and reservoir. The hydraulic cylinder is mechanically connected to the flaps, which consequently causes the flaps to extend or retract when the cylinder moves in response to changes in chamber pressure.

Flap system

The Model

The Cessna flap system model, implemented in SystemModeler, consists of six customized components: a pilot, an electrical system, a power plant, a hydraulic power system, the flaps, and the landing gears.

Cessna flap system model

As shown above, the Cessna model is hierarchical, with several sub levels. The pilot model receives signals from both the electrical subsystem and the flaps, for example, in the form of system pressure data or information about the current flap position. The powerPlant subsystem contains two engines that connect to pumps in the hydraulicPower model, which in turn provides pressurized fluid to the flaps and landingGear subsystems. To avoid a blog post longer than Ulysses, I’m going to leave the detailed exploration of the models up to a forthcoming post, where the modeling process will be described in more detail.

Electrical components

Now that you have a general sense of the model components and their interactions, let’s take some time to think about some potential failures. Despite the risk of aggravating my slight fear of flying, I took a look at some accident reports for different Cessna aircraft. This revealed that failing limit switches, hydraulic leakages, and mechanical failures are examples of flap failures that affect the aircraft at a system level. So let’s include the following scenarios in the failure analysis:

1. A pipe in the flap subsystem is leaking.
2. The mechanical rod that connects the flap to the cylinder is broken.
3. An electrical failure in the flap control valve occurs in mid-air.

Let’s first take a look at the nominal scenario where everything works as it should, and the pilot can enjoy the perks of having a fully functioning flap system. The pilot moves the flap selector switch to positions 10° -> 20° -> 30° -> 0°, which corresponds to takeoff -> approach -> landing -> up. Note that this is quite an odd combination of flap commands to use in real life within a time span of 20 seconds, so it’s just a means of studying the system. It can for example be seen as a test run to see if the flaps are working properly.

First load the WSMLink and define the model.

WSMLink

My colleague Olle conveniently included different failure modes in several components in the Cessna model, so in order to investigate the effects of, for example, a pin-short in a solenoid, I simply have to change the failure mode parameter of a solenoid to pin-short, and then simulate the model.

Simulate model

In the nominal case, I want to make sure that the relevant failure parameters are set to 0, which means that the components are fully functioning. Since the failure modes are structural parameters, I need to use WSMSetValues instead of WSMParameterValues.

WSM Set Values

Which angles do the flaps actually take on compared to those commanded by the pilot in the nominal case?

WSMPlot

As can be seen, the angular position of the flaps follows the commands given by the pilot, with some delay due to the time it takes for the flaps to extend or retract.

Let’s also take a look at the pressure development in the hydraulic relief valve, which corresponds to the pressure supplied to the flaps. Another interesting aspect, especially for electrical failures, is the electrical signal that commands the flaps to extend.

Pressure development

In the plots above, we can see how the pressure peaks correspond to the retraction and extension of the flaps, and how the electrical signal peaks when an extend flap command is issued from the pilot.

Now let’s examine the other scenarios and see how they compare to the nominal scenario.

Scenario: Leaking Pipe

In this failure scenario, the flaps have the same initial position as in the nominal case, but there is a leaking pipe in the flap subsystem. The leakage is injected by changing the value of parameter fm for the pipe in question from 0 to 2.

Leaking pipe

The figures show a simulation of the system with a pipe leakage: to the left, the commanded flap angle and the actual flap angle; to the right, the pressure development in the hydraulic relief valve in subsystem hydraulicPower.

We can see that the leakage reduces system pressure, which in turn causes a reduction in cylinder force. The reduction leads to a slower flap movement, which, seen from a system perspective, curtails the response time. Such a scenario could potentially be dangerous if the pilot is in a situation where the flaps have to be moved quickly, for example, if the plane approaches the runway too fast or at a wrong angle.

Scenario: A Broken Rod

As previously mentioned, the flap subsystem contains a hydraulic cylinder that drives the movement of the flaps. In this scenario, let’s investigate what happens if the rod connected to the flaps is broken, which in the model means that no force can be transferred between the two ends of the rod.

Broken rod

In the two bottom plots, we can see that there is a pressure buildup in the system, and the electrical signal behaves as expected. Despite this, the flaps remain in the up position. Since the rod is broken, the cylinder cannot transfer any force at all to move the flaps (see upper right plot), independent of the flap switch command. In this case, the seemingly small component failure would actually lead to a longer LDR.

Scenario: Mid-Air Electrical Failure

Sometimes failures aren’t discovered until the plane is already in the air, and in such situations, it is even more important to be prepared and have safety procedures that can remedy any problems that might occur. Let’s for example explore the scenario when there is a mid-air electrical failure. The pilot failed to test the flaps before takeoff, and so the retraction command is first used in mid-air. The electrical failure occurs in the flap control valve where the up-solenoid has a pin-short. The shorted solenoid trips the circuit breaker in mid-air, causing the pilot to lose control over the flaps.

Mid-air electrical failure

From the pilot’s point of view, the failure isn’t noticeable until he or she tries to retract the flaps from 10 to 0 degrees, since the extend function is still initially functional. However, the second the pilot tries to move the flaps back up, the short circuit to ground is no longer isolated from the circuit breaker, and all control over the flaps is lost with the unpleasant side effect of the plane suddenly needing a longer runway. Seems like a pretty bad position to be in, right? Actually, it doesn’t necessarily have to be, if we can use our modeling expertise to model and test a safety procedure that might help the situation.

Scenario: Mid-Air Electrical Failure with a Safety Procedure

It’s possible to use the Cessna model to come up with a safety procedure that makes it possible to land the plane safely despite the mid-air electrical failure. Such a procedure could, for instance, be to move the switch to landing and then reset the circuit breaker. When reset, it should be possible to directly move the flaps to landing position and land safely, even though the retract function is still malfunctioning. So let’s see if this maneuver does the trick.

Failure with safety feature

The figures show a simulation of the system with a mid-air electrical failure where the shorted solenoid triggers an emergency flap extension.

The shorted solenoid trips the circuit breaker in mid-air, causing the pilot to lose control over the flaps. The pilot then puts the switch in landing position, resets the circuit breaker, and manages to extend the flaps.

What’s the Conclusion?

So, what about my original question: Could a flap failure increase the LDR so much that the assigned runway becomes too short?

Judging from the failure analysis just performed, it does seem like a plausible scenario. If the increase in the LDR resulting from a flap failure (for example, the mid-air electrical failure discussed above) exceeds the runway margin, then that could potentially happen. However, the model has not been created in cooperation with Cessna, and assumptions have been made regarding, for example, the electrical design and parameter values. In other words, it’s not possible to guarantee that all aspects of the model are 100% accurate or complete. Still, it shows the potential of using modeling as a means of exploring different failure scenarios, how faults can be detected, and how to design safety procedures.

I used Wolfram SystemModeler to analyze faults after a particular sequence of commands, something that could be done during a test procedure, for example. Using the same principles, it’s possible to use SystemModeler to perform fault-code coverage analysis for systems with diagnostic trouble codes. I also tested a proposed safety procedure, and seeing how that interacts and triggers different responses in the system as a whole, such tests have the potential to lead to a better understanding of the human-machine interaction.

If you want to try out some failure modeling yourself, or just get a feel for the tools that I have used in this blog, trial versions of both SystemModeler and Mathematica and available for download online. Also the Wolfram Hydraulic library, along with several other libraries from other domains, can be explored and downloaded from Wolfram’s brand new SystemModeler Library Store.

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Presentations Available from Wolfram Experts Live: New in Mathematica 10 http://blog.wolfram.com/2014/09/24/presentations-available-from-wolfram-experts-live-new-in-mathematica-10/ http://blog.wolfram.com/2014/09/24/presentations-available-from-wolfram-experts-live-new-in-mathematica-10/#comments Wed, 24 Sep 2014 16:35:53 +0000 Jamie Peterson http://blog.internal.wolfram.com/?p=21276 Following one of our most anticipated releases to date, we hosted the virtual workshop Wolfram Experts Live: New in Mathematica 10 to give the Wolfram community the details on this latest version of our flagship product Mathematica.

Mathematica 10

A dozen Wolfram experts and Mathematica developers came together at our headquarters—both in person and remotely via online connections—to take turns showing off new advances in usability, algorithmic functionality, and integration with the Wolfram Cloud. Presenters participated in a live Q&A with the online audience, and in turn were able to hear from Mathematica users and enthusiasts.

All presentations were recorded; videos of individual talks, complete with presentation notebooks, as well as the full event are now available.

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