This section was written by Associate Editor Jean Thilmany.

LUNAR LOOK

On his fourth voyage to the Americas, Christopher Columbus, stranded on Jamaica and in need of assistance from the native residents, used a prediction of the lunar eclipse of February 29, 1504, as a show of power. Now, thanks to researchers at Rensselaer Polytechnic Institute in Troy, N.Y., we can see what that lunar eclipse—and virtually any other—looked like.

The researchers have developed a way to use computer graphics to simulate and render lunar eclipses, which occur when the moon passes into the Earth’s shadow. The computer-generated images, which their creators said are virtually indistinguishable from actual photos of eclipses, offer a chance to look back into history at famous eclipses or to get a peek at future eclipses calculated to occur in the coming years, said Barbara Cutler, assistant professor of computer science at Rensselaer.

The appearance of lunar eclipses varies considerably, with the moon ranging from nearly invisible jet black to deep red, rust, bright copper-red, or orange. The moon’s appearance depends on several different factors, including how sunlight is refracted and scattered in the Earth’s atmosphere.

The Rensselaer model uses celestial geometry of the sun, Earth, and moon, along with data for the Earth’s atmosphere and the moon’s peculiar optical properties to create picture-perfect images of lunar eclipses, Cutler said.

The software can also be configured to show how the eclipse would appear from any geographical perspective on Earth. For example, the same eclipse would look different depending on whether it was viewed in New York, Seattle, or Rome.

“Our models may help with investigations into historical atmospheric phenomena and they could also be of interest to artists looking to add this special effect to their toolbox,” Cutler said.

Theodore Yapo, a graduate student, worked with Cutler to combine and configure models for sunlight, the solar system, and different layers and different effects of the Earth’s atmosphere to develop their lunar eclipse models. To validate the method, the pair compared digital photos of the Feb. 21, 2008, total lunar eclipse with computer-rendered models of the same eclipse. The rendered images were nearly indistinguishable from the photos, Cutler said.

SLOW JAM

For motorists stuck in traffic, the feeling is like being trapped in tar. But researchers looking for a new way to study some kinds of traffic jams say that they behave more like gas explosions.

Normally a traffic tie-up occurs when vehicles reach some kind of bottleneck—such as road construction or an accident—that restricts or halts movement. But the team comprising researchers from the University of Alberta in Edmonton and the Massachusetts Institute of Technology in Cambridge is studying what they call phantom traffic jams, which seem to happen without obvious explanation.

Phantom traffic jams can be created by something as simple as a single driver tapping lightly on the brakes, which inadvertently starts a chain reaction of over-braking by drivers in the following vehicles, said Morris Flynn, a mechanical engineering professor at the University of Alberta.

From an innocuous beginning, eventually a long line of traffic comes to a complete stop. On major freeways in North America, phantom traffic jams can involve hundreds of vehicles and can snarl traffic for hours, Flynn said.

Flynn worked with researchers from MIT to come up with a way to mathematically model phantom jams. To calculate the severity of phantom traffic jams for highways with various speed limits and traffic volumes, the researchers decided to create a model that would mirror the behavior of gas. The behavior could be analyzed via software based on the mathematical model.

“We treat traffic as a chemically reacting gas,” Flynn said. “That is, in the research team’s eyes, traffic flow is a gas and the start of a traffic jam is an explosion and that force ripples outwards engulfing everything in its path.

“Once a detonation wave begins, it keeps expanding outwards,” Flynn added. “By the same token, a phantom traffic jam may start with only a handful of vehicles but then quickly grow in scale and severity.”

The research was published online in June in Physical Review E, published by the American Physical Society.

SECOND SEARCH

First there was Lycos, then Google, and now Microsoft’s Bing is competing to be the world’s most powerful search engine. But no matter how good a search engine you use, you may still need to change your search terms at least once to get to the information you seek.

One researcher at Pennsylvania State University has raised the possibility that the search engine may one day refine the search terms for you, automatically. That researcher has analyzed nearly one million Web searches to detect patterns of query reformulation; he then created models to predict those reformulations.

“The key finding in the research is that we are moving from descriptive aspects to predictive models in Web searching,” said the researcher, Jim Jansen, associate professor of information sciences and technology at the State College, Pa., campus.

Jansen and his colleagues found that 22 percent of queries were reformulated or changed to more precisely convey the information for which the user was searching.

Users typically reformulated their query late in their search session, Jansen said.

“But it appears that the assistance to narrow the query and alternate query terms would be most beneficial immediately after the initial query submission,” he said.

Jansen said his look at how users reformulate their initial query in order to return more pertinent information could lead to more advanced search engines.

“Given that one can predict future states of query formulation based on previous and present states with a reasonable degree of accuracy, one can design information systems that provide query reformulation assistance and automated searching assistance systems,” he said.

CAD CATALOG

Boeing Co. of Chicago recently adopted a 3-D part catalog management and hosting solution that will let engineers share data across multiple CAD systems and among products via a centralized catalog database.

Boeing recently implemented a searchable 3-D parts catalog that lets engineers search for CAD parts. That way, the engineers don’t have to recreate parts  when they’re designing aircraft.

The aircraft maker’s engineering strategy includes using a single source of data for all standard parts. The part geometry is housed in a digital catalog that all engineers can search.

This allows engineers to automatically create standard parts, said Joe Hafner. He’s the product manager for Partsolutions of Milford, Ohio, which makes the product Boeing is using.

The vendor’s 3-D part catalog management allows for quick part access. It also helps engineers comply with Boeing’s engineering strategy, Hafner said.

The catalog includes a search function, which helps engineers reuse already designed parts rather than designing them again from scratch.

The application is integrated with all Boeing design-engineering software, Hafner said.

FISHY ROBOT

As boats and ships ply the waters close to shore, they do unseen damage: They churn up seabeds and riverbeds. This churning action can erode the shoreline and have a deleterious impact on marine plants and aquatic-animal populations.

Researchers are studying an old solution to this problem. They have created a robot with moves that are modeled on fish’s motion. A ship that moves as a fish does through water would erode the shoreline much less than do today’s ships, according to the team at Darmstadt University of Technology in Germany that created the robot.

The team first analyzed videos that depict a fish moving through water. Based on that analysis, they developed a prototype fish robot that duplicated those movements.

Including its tail fin, the fish robot, which is a 5:1 scale model of a gilt-head sea bream, is nearly five feet long.

The fish robot, dubbed Smoky, consists of a skeleton composed of ten segments enshrouded in an elastic skin. The segments are free to move relative to one another, which creates a snaking motion similar to that of a fish swimming through water, according to a statement from the university.

The fish robot’s soft-drive action prevents the churning up of seabeds and riverbeds.

The researchers working on Smoky said they are also studying other fish movements to refine their robot in an attempt to make it even more efficient.

The team is now testing and refining its fish robot using the locomotion patterns of various species of fish to improve its efficiency. The researchers hope to develop a model that is practical for use in future ship and boat locomotion.

FINDING THE LIGHT

Engineers at Dialight Lumidrives, a maker of light emitting diode fixtures in York, England, have turned to a software application to help them quickly select heat sinks that fit within their specialized lighting fixtures.

LEDs can provide light for up to 50,000 hours—as long as the diode’s junction temperature is kept below 248 °F, said Stephen Dixon, senior design engineer at the company.

At temperatures above that, LED lifetime drops considerably.

As is the case with most lighting, LED luminaires are typically air-cooled, which calls for an efficient heat sink that works in any environment.

To address heat removal, engineers at Dialight Lumidrives consider third-party heat sink solutions and also design their own customized heat sinks from die-cast and extruded aluminum, Dixon said.

In order to consider all options, engineers at the company sought a quick way to evaluate heat sink design.

“We want a fast idea of how well a given heat sink will work,” Dixon said. “But we don’t want to have to spend a long time on CAD setup. Our engineers assume static conditions and are not interested in patterns of airflow.

“We want to be able to take a CAD file, paste in some material attributes, add a heat source, run a simulation, and examine results in a few minutes,” he added.

To get quick results, the engineering team now creates its mechanical designs in Pro/Engineer Wildfire from PTC of Needham, Mass. It then simulates and analyses the sink using FloEFD.Pro from the Mentor Graphics’ mechanical analysis division, formerly Flomerics, of Marlborough, Mass. The analysis tool is embedded in the CAD system.

Engineers can now quickly perform a simulation without the need to import the CAD file into a separate analysis package, Dixon said.

Without the simulation and analysis software, engineers may need to make three design iterations to find the right heat sink, Dixon said.

“With the new simulation software, engineers’ predicted results from simulations are spot-on with experimental results so we can get an efficient heat sink design on the first go-around,” he added.

BRIEFLY NOTED

Bunkspeed of Los Angeles has released its HyperShot plug-in for the Pro/Engineer CAD package. The plug-in creates a direct link between HyperShot, a digital camera for 3-D data, and Pro/Engineer Wildfire 2, 3, and 4. /// A maker of 3-D printers, Z Corp. of Burlington, Mass., has released its zp150, a composite build material for its ZPrinter 450 and ZPrinter 650 3-D printers. The material improves the strength and color of 3-D printed models, according to its developer. /// CGTech of Irvine, Calif., the developer of Vericut numerical control simulation and analysis software, announced an enhanced Pro/Engineer-to-Vericut user interface.  /// Vistagy Inc. of Waltham, Mass., has released SyncroFIT 2009, which enables engineers to specify fasteners and holes, load catalog parts, and validate adherence to design rules when creating large aerostructures. /// Savoy Computing Services Ltd., of Kent, England, which makes AutoTrack, vehicle swept path analysis software, has released an update that allows users to access online vehicle libraries. /// The Open Design Alliance of Phoenix has launched DWGdirect.NET, an ODA platform component built for use with the Microsoft .NET framework. The component can read and write DWG/DXF files, render drawings, and edit entity-level properties. /// An authorized Autodesk publisher of interactive courses, TEDCF Publishing of Springville, Calif., has released Autodesk Inventor 2010: Assemblies and Advanced Concepts. It’s the second in a series of certified courses for Autodesk Inventor 2010. /// Knovel of New York, the developer of an online resource that helps engineers find technical information, has launched Knovel Math, available as a Web-based service. The application documents and validates Mathcad worksheets of engineering calculations from reference works. /// PTC of Needham, Mass., has acquired Relex Software Corp. of Greensburg, Pa. Relex provides software and services for analyzing design and field data to help evaluate product reliability.