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Scientists Discover Unexpected Side Effect to Cleaning Up Urban Air

12-19-17

For decades, efforts to reduce air pollution have led to cleaner air in U.S cities like Los Angeles, with subsequent improvements in public health. Those efforts have targeted both nitric oxides and hydrocarbons. Hydrocarbons are emitted from many sources including gasoline-powered cars, trucks, solvents, cleaners used both at home and in industrial settings, and even trees.  Professor Paul O. Wennberg and colleagues have found that there is another chemical pathway for forming organic hydroperoxides—one that occurs at nitric oxide levels substantially higher than can be found in the atmosphere over unpopulated regions. "This is chemistry that does not exist in any of the models of how nitric oxide and hydrocarbons interact," says Professor Wennberg. [Caltech story]

Tags: research highlights ESE Paul Wennberg

Two Holograms in One Surface

12-11-17

Andrei Faraon, Assistant Professor of Applied Physics and Materials Science, graduate student Seyedeh Mahsa Kamali, and colleagues have figured out a way to encode more than one holographic image in a single surface without any loss of resolution. The team developed silicon oxide and aluminum surfaces studded with tens of millions of tiny silicon posts, each just hundreds of nanometers tall. Each nanopost reflects light differently due to variations in its shape and size, and based on the angle of incoming light. [Caltech story]

Tags: research highlights Andrei Faraon APh Seyedeh Mahsa Kamali

Professor Hoffmann Elected to Chinese Academy of Engineering

11-27-17

Michael R. Hoffmann, Theodore Y. Wu Professor of Environmental Science, has been elected to the Chinese Academy of Engineering (CAE). Professor Hoffman was one of 18 foreign experts, including Microsoft founder Bill Gates, who were inducted into the CAE which is the foremost engineering academy in China. [CAE announcement]

Tags: honors ESE Michael Hoffmann

Engineers Model the California Reservoir Network

11-22-17

Professor Venkat Chandrasekaran and graduate student Armeen Taeb have developed an empirical statewide model of the California reservoir network. This work offers reservoir managers insight on how to plan and respond to drought conditions. "The bread and butter of hydrology is using physical laws to describe water phenomena. But the behavior of these reservoirs is not solely determined by physical laws of the water cycle, but also by demands and what these reservoirs are being used for," Taeb explains. [Caltech story]

Tags: EE research highlights CMS Venkat Chandrasekaran Armeen Taeb

The Microscopic Origin of Efficiency Droop in LEDs

11-20-17

Marco Bernardi, Assistant Professor of Applied Physics and Materials Science, and his colleagues’ semiconductor research has shown that the coupling between electrons and thermal vibrations may be sapping energy from Light-emitting diodes—or LEDs. "Our work shows for the first time that the ever-present interaction between electrons with lattice vibrations can, by itself, explain why excited electrons can leak out of the active layer and account for inefficiencies in GaN LEDs," Professor Bernardi says. [Caltech story]

Tags: APhMS research highlights Marco Bernardi

Engineers Create Stable Plasma Ring in Open Air

11-13-17

For the first time, Professor Morteza Gharib and colleagues have created a stable ring of plasma in open air using just a stream of water and a crystal plate. The team fired the water jet at surfaces of different textures and found that the smoother the surface, the clearer the structure of the plasma ring. The ring is stable, and as long as the water continues to flow, the ring maintains its shape and size. [Caltech story]

Tags: research highlights GALCIT MedE Morteza Gharib

Professor Desbrun Interviews Pixar President and Pixar Animation Senior Scientist

10-27-17

Listen to Professor Mathieu Desbrun’s conversation about the history and future of computer graphics research with Ed Catmull (co-founder, Pixar Animation Studios; president, Pixar and Walt Disney Animation Studios) and Tony DeRose (senior scientist, Pixar Animation Studios). [SIGGRAPH Spotlight: Episode 6]

Tags: research highlights CMS Mathieu Desbrun

Laser-Imaging Technology Brought into Focus

10-26-17

Lihong Wang, Bren Professor of Medical Engineering and Electrical Engineering, and colleagues have improved a technique for taking three-dimensional (3-D) microscopic images of tissue, allowing them to see inside living creatures with greater precision than before. "This gives us the ability to look through opaque materials and see what's inside," Professor Wang says. "It's like an extension of the human eye, like Superman's X-ray vision."  [Caltech story]

Tags: EE research highlights MedE Lihong Wang

Teaching Machines How to Learn

10-24-17

Animashree (Anima) Anandkumar, Bren Professor of Computing and Mathematical Sciences, develops efficient techniques to speed up optimization algorithms that underpin machine-learning systems. Speaking about the connections between industry and academia she explains,“bridging the gap between industry and academia is really important. It is a big part of what brought me to Caltech. The sooner we can take theory and deploy it practically, the faster innovation moves and the more impact it can have.” [Interview with Professor Anandkumar]

Tags: research highlights CMS Animashree Anandkumar

Studying Entropy in Metallic Glasses

10-10-17

Brent Fultz, Barbara and Stanley R. Rawn, Jr., Professor of Materials Science and Applied Physics, and colleagues have pinpointed that arrangement of atoms is the main source of an increase in entropy during the glass transition. One persistent mystery about metallic glasses occurs at the so-called "glass transition." A cold metallic glass is hard and brittle, but when it is heated past a certain point—the glass transition—it becomes soft. [Caltech story]

Tags: APhMS research highlights Brent Fultz MatSci