When you think of a beating heart, you might assume it beats at regular intervals, but in actuality, velocity and pressure change with every beat, and the time interval between each beat is different. Now a NASA-developed technology is helping researchers understand blood flow and pressure in ways that may improve treatment for victims of brain injury and stroke.

Medical professionals can use the data from Multimodal Pressure-Flow to create a reliable index of cerebral autoregulation and to help identify impairment of cerebral vasoreactivity, which is caused by medical syndromes that affect the brain, such as stroke, dementia, and traumatic brain injury. Shown here is the complex network of veins and arteries that carry blood to and from the brain.
Dr. Norden Huang, a scientist and mathematician at Goddard Space Flight Center, invented a set of algorithms for analyzing nonlinear and nonstationary signals that developed into a user-friendly signal processing technology for analyzing time-varying processes.

Efficient and adaptive, it can be used to analyze data sets for a wide variety of applications and even improves accuracy when used with linear and stationary signals. Dubbed the Hilbert-Huang Transform (HHT), it is a continuation and adaptation of early 20th century mathematician David Hilbert’s work on signal analysis.

An advantage of HHT over other common signal analysis techniques, like Fourier transforms, is that it is more precise and accurate, capable of sharper filtering while preserving the integrity of the data. It is also flexible with the types of data it can analyze, since it does not require the data sets to be linear and stationary.

As an added bonus, this series of algorithms is relatively easy to implement and operate.

While NASA designed the technology for structural health monitoring and damage detection, like nondestructive testing of the space shuttle orbiters, the applications outside of the Agency are nearly limitless. For example, the HHT method can assist in the understanding of sound and vibrations for highway noise reduction, submarine design, and speech and sound recognition analysis.

It can also help in environmental analysis, like mapping land and water topography or water and wind dynamics. Industrial applications include machine monitoring.

The work on this project led to a Federal Laboratory Consortium “Technology Leadership Award” for the HHT method in 2000, as well as recognition as one of R&D Magazine’s “R&D 100” (a list of the top 100 inventions of the year) in 2001, and the “NASA Government Invention of the Year” in 2003.


When NASA was founded, the U.S. Congress required that the Agency work to make its technologies available to the public. Traditionally, NASA has made public announcements of patents available for license, either through news releases or publication in the monthly Tech Briefs magazine.

Recently, Goddard experimented—successfully—with a new approach to transferring NASA technology to the public by placing a handful of licenses to its patents up for auction. At an auction managed by Ocean Tomo Federal Services LLC, an intellectual property auction house, licenses of 10 U.S. patents and 1 domestic patent application were sold to DynaDx Corporation , of Mountain View, California, a medical technology incubator that develops and markets products to improve clinical diagnostics and prediction of medical problems. This lot of patents included the HHT.

Product Outcome

DynaDx is now using the licensed NASA technology for medical diagnosis and prediction of brain blood flow-related problems, such as stroke, dementia, and traumatic brain injury.