Energy-Minimizing Idle Listening in WiFi-Equipped Mobile Devices

WiFi interface is known to be a primary energy consumer in mobile devices, and idle listening (IL) is the dominant source of energy consumption in WiFi.  Most existing protocols, such as the 802.11 power-saving mode (PSM), attempt to reduce the time spent in IL by sleep scheduling.   However, through an extensive analysis of real-world traffic, we found more than 60% of energy is consumed in IL, even with PSM enabled. 

Energy-Efficient Chip-to-Chip Communication at the Extremes of Computing

The scalability of CMOS technology has driven computation into a diverse range of applications across the power consumption, performance and size spectra. Communication is a necessary adjunct to computation, and whether in the context of high-performance computing, mobile devices or biomedical implants, chip-to-chip communication can take up a significant portion of the overall system power budget. A single interconnect methodology cannot address such a broad range of requirements efficiently.

Sparse Physics and its Applications to Energy Materials

The conventional approach to building physics models is based on physical intuition gained in prior studies of similar systems. Unfortunately, intuition is often faulty. We show that a recently developed technique from information science, compressive sensing (CS), provides a simple, efficient, and systematically improvable way of constructing models in a numerically robust and conceptually simple way. CS is a new paradigm for model building in physics - its models are sparse and just as robust or better than those built by current state-of-the-art approaches.

Confining Light on a Chip: The Science of Optical Micro-Resonators

Like a tuning fork for light, optical resonators have a characteristic set of frequencies at which it is possible to confine light waves. At these frequencies, optical energy can be efficiently stored for lengths of time characterized by the resonator Q factor, roughly the storage time in cycles of oscillation. In the last ten years there has been remarkable progress in boosting this storage time in micro and millimeter-scale optical resonators. Chip-based devices have attained Q factors of nearly 1 billion and micro-machined crystalline devices have provided Qs exceeding 100 billion.

In Situ Synchrotron Studies of Nanoparticle Formation and Growth in Supercritical Fluids

Nanoparticles form the cornerstone in many applications of nanotechnology, and their properties are highly dependent on specific particle characteristics. We have focused on synthesis in supercritical fluids since this approach offers an energy efficient green route for the production of nanomaterials with a very high degree of control of the particle characteristics. However, in order to tailor nanoparticle characteristics insight into their formation and growth is vital and this can be achieved through in situ studies.

The Changing Energy Landscape — A Summary of Key Issues and Trends

Drawing from numerous sources, this tutorial will summarize some of the more important recent developments in the field of energy and project current trends forward to develop some (hopefully) plausible scenarios for what might arise during the next few decades. Some key questions that will be addressed are: Is shale gas an energy bonanza,  an environmental hazard, or both? Will it sideline renewables and electric vehicles? Will it displace coal? Will solar become price competitive without subsidies, and if so when?

Semiconductor Nanostructures in Energy Devices

Semiconducting nanostructures offer potentially revolutionary advancements in the cost and performance of light emitting diodes for solid state lighting and photovoltaic energy converters. GaN based LEDs are usually fabricated on expensive substrates and suffer from a high density of threading dislocations. In addition, the high current performance of the devices is degraded by efficiency decreases (efficiency droop) that seem to be inherent to current designs.

Materials for Organic Photovoltaics: Non-Fullerene Acceptors and Low-Band Gap Dyes for BHJ OPVs

Organic photovoltaic devices (OPVs), that utilize organic small molecules and/or polymers to directly convert sunlight to electricity, are an attractive technology for sustainable, low cost, clean energy production.  For example, solution-processed bulk heterojunction (BHJ) OPVs have attracted much attention because of their potential for flexible, light-weight, large area and low-cost device fabrication.  In particular, fullerene compounds have been the dominating electron acceptor/transport material in BHJ OPVs.  However, fullerene compounds have some disadvantages, such as