Day: 2011-04-19

RESCHEDULED: Bridge Collapses, Our Journey to Work, and other Transportation Challenges (April 19, 7:30 p.m.)

| David Levinson

Cancelled due to adverse weather … Rescheduled for October 18, 2011

I will extend my world tour to Rochester, Minnesota, home to the world famous Mayo Clinic, where I will talk about “Bridge Collapses, Our Journey to Work, and other Transportation Challenges” for the Sigma Xi: The Scientific Research Society


April 19, 7:30 p.m. **Leighton Auditorium, 3rd floor of Siebens Building**
Bridge Collapses, Our Journey to Work, and other Transportation Challenges
(04/19/2011)
David Levinson, Ph.D.
Associate Professor, Department of Civil Engineering, University of Minnesota
Director, Networks, Economics, and Urban Systems (NEXUS) Research Group
Note, this will also be on Second Life, on which the Mayo Clinic has an island.

Beautiful U Day : University of Minnesota

| David Levinson

Beautiful U Day : University of Minnesota

 

Beautiful U Day 2011 is tomorrow, Wednesday April 20. On Beautiful U Day there will be a number of public presentations on transportation and related topics, and a Transportation Expo and used bike sale on Northrop Plaza from 11am – 3pm. Come hear one of the following presentations and attend the Transportation Expo to learn more about sustainable transportation options or to purchased a used bicycle.

Presentations

  • On the East Bank at Coffman Memorial Union, Board Room, Third Floor
    • Will Your Next Car Be Electric? 11:00 am – Noon.  Jukka Kukkanen, PlugInConnect. Come and find out what electric vehicles are and why they might be a right solution for your future transportation needs. This presentation will give you an overview of upcoming models, key characteristics of electric vehicles and comparisons to the vehicles we presently drive. Learn also about investments, cost savings and environmental impacts of electric vehicles.  To prepare yourself  visit www.pluginconnect.com/basics.aspx to get information about electric vehicles.
    • Biofuels, Noon – 1:00 p.m. Active Energy Club student group presents on Biofuels of the future.  Stop by and find out more about the Energy Efficiency Student Alliance and Power Police.
    • Central Corridor Light Rail Transit Construction Impacts, 1:00 – 2:00 p.m. Bob Baker, Executive Director of Parking and Transportation Services at the U of M will provide a comprehensive overview of how the fast-approaching start of construction on the Central Corridor Light Rail Transit Line will impact the Twin Cities Campus.
  • In St. Paul at the Learning and Environmental Sciences Building (formerly VoTech), Room 380
    • Central Corridor Light Rail Transit Construction Impacts, 10:30 – 11:30 a.m. Bob Baker, Executive Director of Parking and Transportation Services at the U of M will provide a comprehensive overview of how the fast-approaching start of construction on the Central Corridor Light Rail Transit Line will impact the Twin Cities Campus.  Also available on UM Connect! https://umconnect.umn.edu/lr/
    • Decay, Fungi, and Biofuels, Noon – 1:00pm. Jonathan Schilling, Assistant Professor, Bioproducts and Biosystems Engineering.  Increasingly, wood-degrading fungi are in focus for their ability to thoroughly deconstruct wood and other nonedible plant tissues, a key stumbling block in commercial conversion of biomass to fuels or other chemicals. This is leading researchers, this presenter included, to look at the mechanisms of wood decomposition as a system instead of simply probing for wood preservative targets. In his talk, Schilling will outline how this type of research can help define a mechanism that is critical in the global carbon cycle while yielding information toward applying a fungal approach in industrial bioprocessing. Also available on UM Connect!  More information athttp://environment.umn.edu/news_events/events/frontiers.html
  • On the West Bank at the Humphrey Center, Stassen Room
    • Bike Sharing in the Twin Cities, 11:30 am – 12:45 p.m. Join Bill Dosset, Executive Director of NiceRide Minnesota, and Tony Hull, Non-Motorized Planning and Evaluation Analyst, Transit for Livable Communities | Bike Walk Twin Cities for a discussion of bike sharing in the Twin Cities.  RSVP to Laura Noble atlnoble@umn.edu

Transportation Expo

Rich Wieber’s Bicycle Stunt Show will dazzle Northrop Mall over the noon-hour as the ReUse Program bike sale offers hundreds of used bikes priced under $80 to the U community. The Expo on Northrop Plaza will feature the U’s sustainable transportation options, free or reduced bike tune-ups, and a competition to build the coolest “Frankenstein” bike from spare parts. Come see the Chevy Volt.  Sustainable commuters will receive a breakfast treat upon arrival at the campus carpool lot, bus stops or bike racks.  A drawing for one of the “Frankenstein” bikes will take place during President Bruininks address at 2:30 pm on Northrop Plaza.  For more information, see Beautiful U.

Moving bikes stay upright – but not for the reasons we thought

| David Levinson

Ars Technica reports: Moving bikes stay upright – but not for the reasons we thought

The phrase “just like riding a bike” is used to refer to something that, once learned, you never forget how to do. As it turns out, bikes make that easy on us. If a typical bicycle is moving forward fast enough, it tends to remain upright and steer in a straight line, even if the rider takes his or her hands off the handlebars. In fact, you can set a bicycle rolling without a rider at all, and it tends to remain upright and roll in a straight line.
…

To test the relative contributions of these factors, the authors eventually built their own computer model of a bicycle and started playing around with various features. It turned out that they could eliminate both the gyroscopic and the negative trail factors, and the bike would still be stable as long as it was moving faster than 2.3 meters (7.5 feet) per second. They could even move steering to the rear wheel and produce a stable design.

The apparently unreasonable stability of different bicycle designs must have suggested that their model had probably lost touch with reality, so the authors went out and built a bike with a counter-rotating wheel to get rid of gyroscopic effects, as well as a negligible (4mm) trailing between the front wheel and the steering. As their model predicted, it tended to stay upright, and would steer into any falls that their grad students tried to induce.

What their math can’t apparently tell them is why so many different bike designs tend to stay upright. “Why does this bicycle steer the proper amounts at the proper times to assure self-stability?” they muse. “We have found no simple physical explanation equivalent to the mathematical statement that all eigenvalues must have negative real parts.” In other words, they can see why the math works out the way it does, but can’t figure out what physical properties correspond to that.

The best they can surmise is that the stability is related to the ability of the bike to steer into a fall if it starts to lean, and that there are multiple ways of constructing a bike that does this.

Science, 2011. DOI: 10.1126/science.1201959