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On emerging micro- and nanoscale thermofluidic technologies
This paper was presented at the 2nd Micro and Nano Flows Conference (MNF2009), which was held at Brunel University, West London, UK. The conference was organised by Brunel University and supported by the Institution of Mechanical Engineers, IPEM, the Italian Union of Thermofluid dynamics, the Process Intensification Network, HEXAG - the Heat Exchange Action Group and the Institute of Mathematics and its Applications.This paper highlights examples of my current research in heat transfer and fluidics at the interface of energy applications and micro- and nanoscale technologies. It is not the scope of this paper to present an
exhaustive account of all current and past activities related to its title. It is rather an account of current research in
my laboratory in this area, containing both the underlying scientific challenges as well as the hoped final outcome in terms of applications. To this end, examples from the areas of energy conversion, as well as energy
transport will be discussed. In the area of energy conversion an original, deformable, direct methanol microfuel cell will be presented made of lightweight, flexible, polymer-based materials. A basic understanding and control of two-phase flows (in this case methanol and carbon dioxide) in microchannels as well as novel materials processing and microfabrication methods are directly related to the performance of such energy conversion devices. In the area of energy conservation and reuse, examples from the information technology are employed. Specifically, new concepts of liquid (water) cooling of chips reaching heat removal rates in excess of 700 W/cm2 in domains with restricted heights of the order of one mm will be presented. One additional advantage of using water to cool high density electronics is energy reuse, due to the potentially much higher exergy content of the coolant compared to air cooled technologies. The last part of the paper focuses on the employment of functional nanostructures such as carbon nanotubes and nanowires of conductive and semiconductive
materials for the efficient transport of electricity and heat and the need for the development of novel technologies for the manufacturing, characterization as well as handling of such nanostructures
Channel Characterization for Chip-scale Wireless Communications within Computing Packages
Wireless Network-on-Chip (WNoC) appears as a promising alternative to
conventional interconnect fabrics for chip-scale communications. WNoC takes
advantage of an overlaid network composed by a set of millimeter-wave antennas
to reduce latency and increase throughput in the communication between cores.
Similarly, wireless inter-chip communication has been also proposed to improve
the information transfer between processors, memory, and accelerators in
multi-chip settings. However, the wireless channel remains largely unknown in
both scenarios, especially in the presence of realistic chip packages. This
work addresses the issue by accurately modeling flip-chip packages and
investigating the propagation both its interior and its surroundings. Through
parametric studies, package configurations that minimize path loss are obtained
and the trade-offs observed when applying such optimizations are discussed.
Single-chip and multi-chip architectures are compared in terms of the path loss
exponent, confirming that the amount of bulk silicon found in the pathway
between transmitter and receiver is the main determinant of losses.Comment: To be presented 12th IEEE/ACM International Symposium on
Networks-on-Chip (NOCS 2018); Torino, Italy; October 201
Powering down technology
This paper will examine the issue of energy consumption resulting from the use of technology. It will identify and evaluate potential solutions currently being deployed by data center managers. In addition, the paper will recommend guidelines for reducing energy consumption for both the individual and business consumer
Toward a Programmable FIB Caching Architecture
The current Internet routing ecosystem is neither sustainable nor economical.
More than 711K IPv4 routes and more than 41K IPv6 routes exist in current
global Forwarding Information Base (FIBs) with growth rates increasing. This
rapid growth has serious consequences, such as creating the need for costly FIB
memory upgrades and increased potential for Internet service outages. And while
FIB memories are power-hungry and prohibitively expensive, more than 70\% of
the routes in FIBs carry no traffic for long time periods, a wasteful use of
these expensive resources. Taking advantage of the emerging concept of
programmable data plane, we design a programmable FIB caching architecture to
address the existing concerns. Our preliminary evaluation results show that the
architecture can significantly mitigate the global routing scalability and poor
FIB utilization issues
High-speed imaging in fluids
High-speed imaging is in popular demand for a broad range of experiments in fluids. It allows for a detailed visualization of the event under study by acquiring a series of image frames captured at high temporal and spatial resolution. This review covers high-speed imaging basics, by defining criteria for high-speed imaging experiments in fluids and to give rule-of-thumbs for a series of cases. It also considers stroboscopic imaging, triggering and illumination, and scaling issues. It provides guidelines for testing and calibration. Ultra high-speed imaging at frame rates exceeding 1 million frames per second is reviewed, and the combination of conventional experiments in fluids techniques with high-speed imaging techniques are discussed. The review is concluded with a high-speed imaging chart, which summarizes criteria for temporal scale and spatial scale and which facilitates the selection of a high-speed imaging system for the applicatio
Pretreatment Processes of Biomass for Biorefineries: Current Status and Prospects
ProducciĂłn CientĂficaThis article seeks to be a handy document for the academy and the industry to get quickly up to speed on the current status and prospects of biomass pretreatment for biorefineries. It is divided into two biomass sources: vegetal and animal. Vegetal biomass is the material produced by plants on land or in water (algae), consuming sunlight, CO2, water, and soil nutrients. This includes residues or main products from, for example, intensive grass crops, forestry, and industrial and agricultural activities. Animal biomass is the residual biomass generated from the production of food from animals (e.g., manure and whey). This review does not mean to include every technology in the area, but it does evaluate physical pretreatments, microwave-assisted extraction, and water treatments for vegetal biomass. A general review is given for animal biomass based in physical, chemical, and biological pretreatments
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