CVD grown nitrogen doped graphene is an exceptional visible-light driven phot...Pawan Kumar
The photocatalytic potential of large area CVD grown nitrogen doped graphene (NGr) has been explored though the chemical transformation of 4-nitrobenzene thiol into p,p'-dimercaptoazobenzene. Decoration of NGr with Ag nanocubes with rounded edges to form NGr/Ag nanohybrids resulted in a slight increase in the work-function and a decrease in the n-type character of NGr due to ground state transfer of negative charge from NGr to Ag. The Ag nanocubes exhibited a localized surface plasmon resonance (LSPR) at ~425 nm. When the NGr/Ag nanohybrids were illuminated with visible light of wavelength close to the LSPR peak, Kelvin probe force microscopy (KPFM) indicated a dramatic change in surface potential of −225 mV and Raman spectra detected electron accumulation in NGr, which are attributed to a high local field enhancement-mediated hot electron injection into NGr and the formation of long-lived charge separated states. Pristine nitrogen doped graphene and its coupled system with plasmonic Ag nanoparticles showed superior photocatalytic performance compared to bare plasmonic Ag catalyst. While standalone Ag NPs were unable to complete the transformation of 4-NBT into DMAB even at a laser power of 10 mW, NGr/Ag nanohybrids completed this transformation at a laser power of 1 mW, pointing to the high photoreduction strength of NGr/Ag. Density functional theory (DFT) based computational modeling was used to examine the electronic structure of graphene doped with graphitic, pyridinic and pyrrolic nitrogen dopant atoms. DFT results indicated an enhanced chemical reactivity of NGr due to stronger localization of charge at the dopant sites and a pronounced difference in the projected density of states (PDOS) for carbon atoms in proximity to, and distant from, the nitrogen dopant sites.
GlobalInvacom, a British company, invented the optical LNB and has since expanded its line of fibre optic products. They have introduced new versions of optical LNBs compatible with offset antennas as well as a system to transmit satellite and terrestrial signals over one optical cable. Most recently, GlobalInvacom developed an underground optical cable designed for burial and a housing that provides eight optical connections. The company continues to develop new solutions to expand the capabilities of its optical reception systems.
The document discusses applying a systems engineering approach to address issues with civil timekeeping. It poses questions about characterizing the problem, capturing requirements, and engaging stakeholders. It suggests comparing real and fictional models of timekeeping to understand requirements. The document emphasizes understanding the problem before proposing solutions and gaining consensus from stakeholders on requirements.
- MFG companies have high material costs, low operating margins, and asset-intensive business models with low returns.
- The industry is not very attractive due to fierce competition, dominant customers and suppliers that dictate prices and margins.
- MFG industries also experience high cyclicality with demand falling drastically during recessions.
Whitnee Alexandria Jenkins introduces herself, providing her birthdate, parents' names, siblings and their children. She notes that she played softball her whole life but is not playing in college this year. She lists her fears of frogs, bugs and crawling things. She states that she is an entrepreneur and elementary education major, and that she loves Jesus, being a mom, and secretly loves Alabama football.
This document defines and discusses foreign direct investment (FDI). It notes that FDI includes mergers and acquisitions as well as building new facilities. There are three main types of FDI: horizontal FDI which duplicates activities in new markets; platform FDI which uses one country as an export base; and vertical FDI which moves across different value chains. The document also examines factors that influence FDI decisions like market access and efficiency, and discusses advantages like technological development and disadvantages like lack of skills development in host countries.
Spartacus was originally a Thracian shepherd who joined the Roman army but grew tired of it. He tried to escape with his wife but was captured and sold into slavery. He became a skilled gladiator but planned an uprising with other gladiators. They successfully escaped the gladiator school and began raiding villas, growing their rebel army to 100,000 slaves and former gladiators led by Spartacus. They defeated several Roman generals in battle but Spartacus now plans to march on Sicily to cut off Rome's food supply.
CVD grown nitrogen doped graphene is an exceptional visible-light driven phot...Pawan Kumar
The photocatalytic potential of large area CVD grown nitrogen doped graphene (NGr) has been explored though the chemical transformation of 4-nitrobenzene thiol into p,p'-dimercaptoazobenzene. Decoration of NGr with Ag nanocubes with rounded edges to form NGr/Ag nanohybrids resulted in a slight increase in the work-function and a decrease in the n-type character of NGr due to ground state transfer of negative charge from NGr to Ag. The Ag nanocubes exhibited a localized surface plasmon resonance (LSPR) at ~425 nm. When the NGr/Ag nanohybrids were illuminated with visible light of wavelength close to the LSPR peak, Kelvin probe force microscopy (KPFM) indicated a dramatic change in surface potential of −225 mV and Raman spectra detected electron accumulation in NGr, which are attributed to a high local field enhancement-mediated hot electron injection into NGr and the formation of long-lived charge separated states. Pristine nitrogen doped graphene and its coupled system with plasmonic Ag nanoparticles showed superior photocatalytic performance compared to bare plasmonic Ag catalyst. While standalone Ag NPs were unable to complete the transformation of 4-NBT into DMAB even at a laser power of 10 mW, NGr/Ag nanohybrids completed this transformation at a laser power of 1 mW, pointing to the high photoreduction strength of NGr/Ag. Density functional theory (DFT) based computational modeling was used to examine the electronic structure of graphene doped with graphitic, pyridinic and pyrrolic nitrogen dopant atoms. DFT results indicated an enhanced chemical reactivity of NGr due to stronger localization of charge at the dopant sites and a pronounced difference in the projected density of states (PDOS) for carbon atoms in proximity to, and distant from, the nitrogen dopant sites.
GlobalInvacom, a British company, invented the optical LNB and has since expanded its line of fibre optic products. They have introduced new versions of optical LNBs compatible with offset antennas as well as a system to transmit satellite and terrestrial signals over one optical cable. Most recently, GlobalInvacom developed an underground optical cable designed for burial and a housing that provides eight optical connections. The company continues to develop new solutions to expand the capabilities of its optical reception systems.
The document discusses applying a systems engineering approach to address issues with civil timekeeping. It poses questions about characterizing the problem, capturing requirements, and engaging stakeholders. It suggests comparing real and fictional models of timekeeping to understand requirements. The document emphasizes understanding the problem before proposing solutions and gaining consensus from stakeholders on requirements.
- MFG companies have high material costs, low operating margins, and asset-intensive business models with low returns.
- The industry is not very attractive due to fierce competition, dominant customers and suppliers that dictate prices and margins.
- MFG industries also experience high cyclicality with demand falling drastically during recessions.
Whitnee Alexandria Jenkins introduces herself, providing her birthdate, parents' names, siblings and their children. She notes that she played softball her whole life but is not playing in college this year. She lists her fears of frogs, bugs and crawling things. She states that she is an entrepreneur and elementary education major, and that she loves Jesus, being a mom, and secretly loves Alabama football.
This document defines and discusses foreign direct investment (FDI). It notes that FDI includes mergers and acquisitions as well as building new facilities. There are three main types of FDI: horizontal FDI which duplicates activities in new markets; platform FDI which uses one country as an export base; and vertical FDI which moves across different value chains. The document also examines factors that influence FDI decisions like market access and efficiency, and discusses advantages like technological development and disadvantages like lack of skills development in host countries.
Spartacus was originally a Thracian shepherd who joined the Roman army but grew tired of it. He tried to escape with his wife but was captured and sold into slavery. He became a skilled gladiator but planned an uprising with other gladiators. They successfully escaped the gladiator school and began raiding villas, growing their rebel army to 100,000 slaves and former gladiators led by Spartacus. They defeated several Roman generals in battle but Spartacus now plans to march on Sicily to cut off Rome's food supply.
Este documento describe los principios fundamentales de la dinámica, incluyendo las cuatro fuerzas fundamentales, las leyes de Newton, y conceptos como fuerza, masa, cantidad de movimiento, impulso, y sistemas de referencia. Explica cómo las interacciones entre cuerpos dan lugar al movimiento y cómo la dinámica analiza el movimiento y las fuerzas que lo causan a través de solo tres leyes.
Soalan latihan matematik tahun 1 ( Ruang )Rose Merah
Dokumen berisi soalan latihan matematik tentang bentuk geometri seperti kuboid, kubus, segi empat sama, segi tiga, segi empat tepat, bulat, pentagon, dan bilangan sisi serta bucu objek geometri. Terdapat jawapan untuk setiap soalan beserta umpan balik sama ada jawapan benar atau salah.
El documento describe diferentes señales acústicas y luminosas utilizadas por agentes de tránsito y en semáforos para regular el tráfico. Los silbidos del agente de tránsito se usan para dar órdenes a los usuarios de las vías, donde combinaciones específicas de silbidos largos y cortos indican parada, vía libre o detener a un conductor. Las sirenas o pitos de los vehículos llaman la atención de conductores y peatones. Finalmente, existen semáforos vehiculares y peaton
IBM Business Analytics and Optimization - Traffic Management with IBM InfoSph...IBM Sverige
Professor Haris och hans forskare på KTH har ett samarbete med de som utvecklar InfoSphere Streams på IBM Research. I detta projektet analyseras trafikdata från Stockholmsområdet för att se hur man kan nyttja informationen på bästa sätt för att styra trafiken smartare och informera resenärerna om hur man tar sig fram på bästa sätt.
Förutom själva Stockholmsområdet, så analyserar man trafiken till/från Arlanda. Bland annat vill man prediktera sannolikheten för att man kommer i tid till sin flygavgång på Arlanda beroende på vilken tid man skall åka och beroende på vilket transportsätt man väljer. KTH är vinnare till priset för en smartare planet 2010.
Talare: Haris N. Koutsopoulos, Professor and Head of Transportation and Logistics Division, KTH
Denna presentation hölls på ett seminariepass för Business Analytics & Optimization under IBM Software Day 2010.
The document discusses Simplify, a framework for enabling fast functional simulation of multiprocessor system-on-chips (MPSoCs). Simplify uses an abstract MPSoC platform model to allow for easy modeling of MPSoC architectures and fast behavioral simulation. It integrates an operating system and supports tasks migration and communication between processors. Experimental results show that Simplify achieves scalable simulation performance and allows for online design, simulation, and debugging of MPSoCs.
This document summarizes a presentation given by Dominique Thomas on opportunities for new business models using grid computing. Some key points discussed include:
- Trends in high performance computing showing increasing demand for more computing power and data storage.
- European projects like BEinGRID and EGEE that are developing grid infrastructure for e-science applications.
- Challenges faced by CGGVeritas in seismic processing like needing more computing power and better management of large datasets and computing resources.
- Potential benefits of adopting grid computing for CGGVeritas including better optimization of IT resources, ability to solve more complex problems, knowledge sharing, and new business opportunities.
Distributed Data Analysis with Hadoop and R - OSCON 2011Jonathan Seidman
This document summarizes a presentation on interfacing Hadoop and R for distributed data analysis. It introduces Hadoop and R, describes options for running R on Hadoop including Hadoop Streaming and Hadoop Interactive (Hive), and provides an example use case of analyzing airline on-time performance data. Key points include interfacing Hadoop and R at the cluster level to bring parallel processing capabilities to R, and using tools like Hadoop Streaming and RHIPE to allow R code to be run on Hadoop clusters.
This document discusses various techniques for determining location using GPS and other methods. It provides examples of using GPS data with Arduino, including reading NMEA GPS data strings, using libraries like Adafruit_GPS and TinyGPS++, logging GPS data to an SD card, and visualizing logged GPS tracks on a site like GPSVisualizer. It also briefly mentions potential applications like autonomous route finding, parsing and processing GPS data, and using GPS with drones or wearable devices.
A2 Structure Of Source Models Measurement Methods R Buetikoferahmad bassiouny
The document discusses aircraft noise source modeling. It describes the structure of source models, including sound power level directivity, operation conditions and other parameters. It also discusses different measurement methods that can be used to obtain data for the source models, such as in-flight measurements under operational conditions, arranged in-flight measurements, and analyzing processed data from manufacturers. The measurements require precision tracking and synchronization to attribute sound recordings to specific aircraft types, speeds, thrust settings and other factors.
The document discusses cloud computing and the AIST Super Cloud. It provides details on 3 common cloud platforms: Infrastructure as a Service (IaaS), Platform as a Service (PaaS), and Software as a Service (SaaS). It then describes AIST's transition from its Super Cluster to the Green Cloud and newer Super Cloud, including hardware specifications. Key cloud management platforms are outlined, including Rocks, Eucalyptus, OpenStack, and OpenNebula. The document focuses on AIST's adoption and use of cloud computing technologies for research.
This document summarizes the number 1 supercomputers in the TOP500 list from 1993 to 2012. It profiles each system that achieved the top spot, including key details like the organization that owned it, specifications like the number of cores and theoretical peak performance, and interconnect technology. Over the past 20 years, the performance of the fastest supercomputers has grown enormously, from tens of gigaflops to tens of petaflops. Visitors to the TOP500 20th anniversary booth can view posters on each number 1 system and learn about trends that have emerged over the history of the list.
The document discusses MPEG-4, a standard for multimedia coding. It was originally intended for low bitrate coding but later expanded its scope. MPEG-4 allows coding of audio-visual objects rather than just pixels, supports interactivity and universal access. It includes parts for video, audio, and other functionalities. Key features of MPEG-4 video include coding of video object planes (VOPs), shape coding, and various scalabilities.
The document discusses the MPEG-4 standard for multimedia coding and transmission. MPEG-4 allows coding of audio-visual objects rather than just pixels, supports content-based interactivity, and aims for universal access and high compression over a wide bitrate range. It describes MPEG-4 video coding including video object planes (VOPs), shape coding, motion compensation, and supports features like spatial and temporal scalability.
The document discusses the MPEG-4 standard for multimedia coding and transmission. MPEG-4 allows coding of audio-visual objects rather than just pixels, supports content-based interactivity, and aims for universal access and high compression over a wide bitrate range. It describes MPEG-4 video coding including coding of video object planes using motion compensation and DCT, as well as shape coding using binary and grayscale alpha planes.
The document summarizes the key components of the outside local loop distribution plant that distributes telephone service from the central office to subscribers. It describes how the central office feeder cable terminates at the serving area interface, where distribution cables carry pairs to aerial drop wires or buried service wires. Key points like manholes, underground cables, and cable numbering systems are explained. The purpose is to provide reference on locating specific cable pairs to check for unauthorized equipment or gain a better understanding of the local distribution infrastructure.
The document discusses digital media production at VRT Medialab. It provides three case studies:
1) Media Asset Management - How to effectively reuse large amounts of unstructured content.
2) Non-linear Distribution - Using digital broadcasting and streaming to distribute radio online and on-demand.
3) Computer Integrated Manufacturing - Using CAD/CAM tools to integrate the production process for drama.
The document discusses the adoption of RDFa and structured data, also known as the "Wave", by major websites like Yahoo, Google, and Facebook between 2008-2010. It provides timelines showing when each site began supporting different types of structured data through RDFa, such as reviews, events, recipes, and products. The growing use of RDFa led to increases in backlinks and click-through rates, demonstrating the importance of structured data for search engine optimization.
This document discusses free-space optical (FSO) links, which transmit optical signals through the atmosphere without fiber. It provides a history of optical communication beginning with Bell's photophone in 1880. The document outlines the basic characteristics and advantages/disadvantages of FSO links. It also presents models to characterize laser beams, power budgets, and link margins for FSO systems. Overall, the document provides an overview of FSO link technology and modeling.
Este documento describe los principios fundamentales de la dinámica, incluyendo las cuatro fuerzas fundamentales, las leyes de Newton, y conceptos como fuerza, masa, cantidad de movimiento, impulso, y sistemas de referencia. Explica cómo las interacciones entre cuerpos dan lugar al movimiento y cómo la dinámica analiza el movimiento y las fuerzas que lo causan a través de solo tres leyes.
Soalan latihan matematik tahun 1 ( Ruang )Rose Merah
Dokumen berisi soalan latihan matematik tentang bentuk geometri seperti kuboid, kubus, segi empat sama, segi tiga, segi empat tepat, bulat, pentagon, dan bilangan sisi serta bucu objek geometri. Terdapat jawapan untuk setiap soalan beserta umpan balik sama ada jawapan benar atau salah.
El documento describe diferentes señales acústicas y luminosas utilizadas por agentes de tránsito y en semáforos para regular el tráfico. Los silbidos del agente de tránsito se usan para dar órdenes a los usuarios de las vías, donde combinaciones específicas de silbidos largos y cortos indican parada, vía libre o detener a un conductor. Las sirenas o pitos de los vehículos llaman la atención de conductores y peatones. Finalmente, existen semáforos vehiculares y peaton
IBM Business Analytics and Optimization - Traffic Management with IBM InfoSph...IBM Sverige
Professor Haris och hans forskare på KTH har ett samarbete med de som utvecklar InfoSphere Streams på IBM Research. I detta projektet analyseras trafikdata från Stockholmsområdet för att se hur man kan nyttja informationen på bästa sätt för att styra trafiken smartare och informera resenärerna om hur man tar sig fram på bästa sätt.
Förutom själva Stockholmsområdet, så analyserar man trafiken till/från Arlanda. Bland annat vill man prediktera sannolikheten för att man kommer i tid till sin flygavgång på Arlanda beroende på vilken tid man skall åka och beroende på vilket transportsätt man väljer. KTH är vinnare till priset för en smartare planet 2010.
Talare: Haris N. Koutsopoulos, Professor and Head of Transportation and Logistics Division, KTH
Denna presentation hölls på ett seminariepass för Business Analytics & Optimization under IBM Software Day 2010.
The document discusses Simplify, a framework for enabling fast functional simulation of multiprocessor system-on-chips (MPSoCs). Simplify uses an abstract MPSoC platform model to allow for easy modeling of MPSoC architectures and fast behavioral simulation. It integrates an operating system and supports tasks migration and communication between processors. Experimental results show that Simplify achieves scalable simulation performance and allows for online design, simulation, and debugging of MPSoCs.
This document summarizes a presentation given by Dominique Thomas on opportunities for new business models using grid computing. Some key points discussed include:
- Trends in high performance computing showing increasing demand for more computing power and data storage.
- European projects like BEinGRID and EGEE that are developing grid infrastructure for e-science applications.
- Challenges faced by CGGVeritas in seismic processing like needing more computing power and better management of large datasets and computing resources.
- Potential benefits of adopting grid computing for CGGVeritas including better optimization of IT resources, ability to solve more complex problems, knowledge sharing, and new business opportunities.
Distributed Data Analysis with Hadoop and R - OSCON 2011Jonathan Seidman
This document summarizes a presentation on interfacing Hadoop and R for distributed data analysis. It introduces Hadoop and R, describes options for running R on Hadoop including Hadoop Streaming and Hadoop Interactive (Hive), and provides an example use case of analyzing airline on-time performance data. Key points include interfacing Hadoop and R at the cluster level to bring parallel processing capabilities to R, and using tools like Hadoop Streaming and RHIPE to allow R code to be run on Hadoop clusters.
This document discusses various techniques for determining location using GPS and other methods. It provides examples of using GPS data with Arduino, including reading NMEA GPS data strings, using libraries like Adafruit_GPS and TinyGPS++, logging GPS data to an SD card, and visualizing logged GPS tracks on a site like GPSVisualizer. It also briefly mentions potential applications like autonomous route finding, parsing and processing GPS data, and using GPS with drones or wearable devices.
A2 Structure Of Source Models Measurement Methods R Buetikoferahmad bassiouny
The document discusses aircraft noise source modeling. It describes the structure of source models, including sound power level directivity, operation conditions and other parameters. It also discusses different measurement methods that can be used to obtain data for the source models, such as in-flight measurements under operational conditions, arranged in-flight measurements, and analyzing processed data from manufacturers. The measurements require precision tracking and synchronization to attribute sound recordings to specific aircraft types, speeds, thrust settings and other factors.
The document discusses cloud computing and the AIST Super Cloud. It provides details on 3 common cloud platforms: Infrastructure as a Service (IaaS), Platform as a Service (PaaS), and Software as a Service (SaaS). It then describes AIST's transition from its Super Cluster to the Green Cloud and newer Super Cloud, including hardware specifications. Key cloud management platforms are outlined, including Rocks, Eucalyptus, OpenStack, and OpenNebula. The document focuses on AIST's adoption and use of cloud computing technologies for research.
This document summarizes the number 1 supercomputers in the TOP500 list from 1993 to 2012. It profiles each system that achieved the top spot, including key details like the organization that owned it, specifications like the number of cores and theoretical peak performance, and interconnect technology. Over the past 20 years, the performance of the fastest supercomputers has grown enormously, from tens of gigaflops to tens of petaflops. Visitors to the TOP500 20th anniversary booth can view posters on each number 1 system and learn about trends that have emerged over the history of the list.
The document discusses MPEG-4, a standard for multimedia coding. It was originally intended for low bitrate coding but later expanded its scope. MPEG-4 allows coding of audio-visual objects rather than just pixels, supports interactivity and universal access. It includes parts for video, audio, and other functionalities. Key features of MPEG-4 video include coding of video object planes (VOPs), shape coding, and various scalabilities.
The document discusses the MPEG-4 standard for multimedia coding and transmission. MPEG-4 allows coding of audio-visual objects rather than just pixels, supports content-based interactivity, and aims for universal access and high compression over a wide bitrate range. It describes MPEG-4 video coding including video object planes (VOPs), shape coding, motion compensation, and supports features like spatial and temporal scalability.
The document discusses the MPEG-4 standard for multimedia coding and transmission. MPEG-4 allows coding of audio-visual objects rather than just pixels, supports content-based interactivity, and aims for universal access and high compression over a wide bitrate range. It describes MPEG-4 video coding including coding of video object planes using motion compensation and DCT, as well as shape coding using binary and grayscale alpha planes.
The document summarizes the key components of the outside local loop distribution plant that distributes telephone service from the central office to subscribers. It describes how the central office feeder cable terminates at the serving area interface, where distribution cables carry pairs to aerial drop wires or buried service wires. Key points like manholes, underground cables, and cable numbering systems are explained. The purpose is to provide reference on locating specific cable pairs to check for unauthorized equipment or gain a better understanding of the local distribution infrastructure.
The document discusses digital media production at VRT Medialab. It provides three case studies:
1) Media Asset Management - How to effectively reuse large amounts of unstructured content.
2) Non-linear Distribution - Using digital broadcasting and streaming to distribute radio online and on-demand.
3) Computer Integrated Manufacturing - Using CAD/CAM tools to integrate the production process for drama.
The document discusses the adoption of RDFa and structured data, also known as the "Wave", by major websites like Yahoo, Google, and Facebook between 2008-2010. It provides timelines showing when each site began supporting different types of structured data through RDFa, such as reviews, events, recipes, and products. The growing use of RDFa led to increases in backlinks and click-through rates, demonstrating the importance of structured data for search engine optimization.
This document discusses free-space optical (FSO) links, which transmit optical signals through the atmosphere without fiber. It provides a history of optical communication beginning with Bell's photophone in 1880. The document outlines the basic characteristics and advantages/disadvantages of FSO links. It also presents models to characterize laser beams, power budgets, and link margins for FSO systems. Overall, the document provides an overview of FSO link technology and modeling.
High-Performance In0.75Ga0.25As Implant-Free n-Type MOSFETs for Low Power App...ayubimoak
This document discusses high-performance implant-free (IF) n-type MOSFETs using an In0.75Ga0.25As channel for low power applications. Device simulations show that an IF InGaAs MOSFET with a 15nm gate length can achieve up to 1800 μA/μm drain current, 5100 μS/μm transconductance, and cutoff frequencies over 1600 GHz. The IF MOSFET structure avoids issues with channel doping and offers improved electrostatic control, enabling it to maintain high performance to shorter channel lengths compared to conventional MOSFETs.
This document provides an introduction to asynchronous input/output (AIO), IO reactors, callbacks, and context switches in POSIX realtime evented patterns. It discusses topics like the call stack, context switches between threads and fibers, different threading models in Ruby, the reactor pattern for event-driven programming, POSIX asynchronous IO extensions, AIO control blocks and operations, and how a fibered IO interpreter could improve performance for IO-bound applications.
NASA-NOAA Cooperative Supports for Aqua and Aura Missionsledlow
How NOAA and NASA established an effective working relationship at the Fairbanks Command and Data Acquisition Station. Presented at the 2005 Ground Systems Architecture Workshop.
The document discusses analyzing the brightness variation of the SX Phoenicis variable star XX Cyg using differential photometry on images taken with different optical filters. It outlines the background on variable stars, the author's senior thesis project to determine XX Cyg's period using brightness data from V and R filter images, and the theory that SX Phoenicis stars pulsate radially and nonradially. The methods section describes the telescope and camera used to acquire data, and the process of calibration, aperture photometry, and determining the period from the brightness information.
1. Astronomical
Data
Compression:
Algorithms
&
Architectures
Rob
Seaman
–
Na#onal
Op#cal
Astronomy
Observatory
William
Pence
–
NASA
/
Goddard
Space
Flight
Center
Richard
White
–
Space
Telescope
Science
Ins#tute
Séverin
Gaudet
–
Na#onal
Research
Council
Canada
See
also
poster
57,
“Op#mal
Compression
Methods
for
Floa#ng-‐point
Format
Images”,
Pence,
et
al.
Astronomical
Data
Analysis
SoAware
&
Systems
XIX
–
Sapporo,
Japan
2. Agenda
• Overview
–
Rob
• Tile
compression
and
CFITSIO
–
Bill
• Experiences
with
FITS
compression
in
a
large
astronomical
archive
–
Séverin
• Lossy
compression
–
Rick
• Open
discussion
• Door
prize!
Thanks
to
Pete
Marenfeld
&
Koji
Mukai
5
October
2009
2
3. Overview
• FITS
Ule
compression
• Rice
algorithm
• CFITSIO
/
FPACK
• IRAF
and
community
soAware
• The
ubiquity
of
noise:
opUmal
DN
encoding
• The
role
of
sparsity:
compressive
sensing
• An
informaUon
theory
example
5
October
2009
3
4. Overview
• FITS
Ule
compression
• Rice
algorithm
• CFITSIO
/
FPACK
• IRAF
and
community
soAware
• The
ubiquity
of
noise:
opUmal
DN
encoding
• The
role
of
sparsity:
compressive
sensing
• An
informaUon
theory
example
5
October
2009
4
5. References
• Too
many
ADASS
presentaUons
to
list
• See
references
within:
“Lossless
Astronomical
Image
Compression
and
the
Effects
of
Noise”,
Pence,
Seaman
&
White,
PASP
v121
n878
2009,
hPp://arxiv.org/abs/0903.2140v1
5
October
2009
5
6. FITS
Ule
compression
• ADASS
1999
(Pence,
White,
Greenfield,
Tody)
• FITS
ConvenUon
v2.1,
2009
• Images
mapped
onto
FITS
binary
tables
• Headers
remain
readable
• Tiling
permits
rapid
RW
access
• Supports
mulUple
compression
algorithms
• First
&
every
copy
can
be
compressed
5
October
2009
6
7. Rice
algorithm
• Fast
(difference
coding)
– near
opUmum
compression
raUo
– throughput
is
key,
not
just
storage
volume
• Numerical,
not
character-‐based
like
gzip
• Depends
on
pixel
value
so
BITPIX
=
32
compresses
to
same
size
as
BITPIX
=
16
5
October
2009
7
8. CFITSIO
/
FPACK
• fpack
can
be
swapped
in
for
gzip
&
funpack
for
gunzip
• Library
support
(eg,
CFITSIO)
allows
jpeg-‐like
access
–
compression
built
into
the
format
• More
opUons
means
more
parameters
–
sejng
appropriate
defaults
is
key
5
October
2009
8
9. IRAF
and
community
soAware
• Tile
compression
can
&
should
be
supported
by
all
soAware
that
reads
FITS
• Instrument
and
pipeline
soAware
may
benefit
strongly
from
wri#ng
compressed
FITS
• Transport
&
storage
always
benefit
• IRAF
fitsuUl
package
in
beta
tesUng
• Work
on
a
new
IRAF
FITS
kernel
pending
• VO
applicaUons
and
services
5
October
2009
9
10. The
ubiquity
of
noise
• Noise
is
incompressible
• Signals
are
correlated
– physically
– instrumentally
• Shannon
entropy:
H
=
–
Σ
p
log
p
– depends
only
on
the
probabiliUes
of
the
states
– measures
“irreducible
complexity”
of
the
data
5
October
2009
10
11. OpUmal
DN
encoding
• CCD
“square-‐rooUng”
• Variance
stabilizaUon,
more
generally
– many
staUsUcal
methods
assume
homoscedasUcity
– generalized
Anscombe
transform
• FoundaUons
of
the
empirical
world
view:
– ergodicity
(staUsUcal
homogeneity)
– Markov
processes
(memoryless
systems)
• hPp://www.aspbooks.org/publica#ons/411/101.pdf
5
October
2009
11
12. The
role
of
sparsity
• For
most
astronomical
data,
compression
raUo
depends
only
on
the
background
noise
– Sparse
signals
are
negligible
(in
whatever
axes)
– Noise
is
incompressible
R
=
BITPIX
/
(Nbits
+
K)
K
is
about
1.2
for
Rice
5
October
2009
12
13. Compression
raUo
Mosaic
II
Compression
correlates
closely
with
noise
DisUncUve
funcUonal
behavior
For
three
very
different
comp.
algorithms
R
For
flat-‐field
and
bias
exposures
as
well
as
for
science
data
That
is,
for
pictures
of:
the
sky
a
lamp
in
the
dome
no
exposure
at
all
Signal
doesn’t
maser!
16
Dec
2008
Noise
bits
14. –8–
A
beser
compression
diagram
15
R
1.2
R
=
BITPIX
/
(Nbits
+
K)
Lossy
algorithms
shi^
le^
to
move
down
Compressed bits per pixel
1.5
10
EffecUve
BITPIX:
2.0
BITEFF
=
BITPIX
/
R
5 K
BITEFF
=
Nbits
+
K
4 4.0
3
GZIP
Line
with:
2 Rice
1 Hcompress
Slope
=
1
0 0 Margin
for
improvement
Intercept
=
K
0 5 10 15
Nbits Noise
16
Dec
2008
Fig. 1.— Plot of compressed bits per pixel versus the number of noise bits in 16-bit synthetic
images. The solid lines are generated from the images that have N bits of pure noise, and the
15. Compressive
sensing
• Real
world
data
are
oAen
sparse
(correlated)
• Nyquist/Shannon
sampling
applies
broadly
• But
we
can
do
even
beser
if
we
sample
against
purpose-‐specific
axes:
hPp://www.dsp.ece.rice.edu/cs
hPp://nuit-‐blanche.blogspot.com
• Herschel
proof
of
concept,
Starck,
et
al.
• CS
is
about
the
sampling
theorem
• OpUmal
encoding
is
about
quanUzaUon
5
October
2009
15
16. An
informaUon
theory
example
hPp://www.mapsofconsciousness.com/12coins
example of objective
5
October
2009
16
About the Coins
If you like this game send feedback
17. Compression
=
opUmal
representaUon
A. 11
coins
all
the
same
+
1
coin,
idenUcal
except
for
weight
B. Scale
to
weigh
groups
of
coins
C. In
only
3
steps,
must
idenUfy:
the
coin
that
is
different
and
whether
it
is
light
or
heavy
“The
12-‐balls
Problem
as
an
IllustraUon
of
the
ApplicaUon
of
InformaUon
Theory”
–
R.H.
Thouless,
1970,
Math.
GazePe,
v54n389.
5
October
2009
17
18. How
to
solve
a
problem
• First,
define
the
problem
– second,
entertain
soluUons
– third,
iterate
(don’t
give
up)
• More
basic
yet,
what
is
the
goal?
– to
solve
the
problem?
– or
to
understand
how
to
solve
it?
• StaUng
a
problem
constrains
its
soluUons
5
October
2009
18
19. What
do
we
know?
• One
bit
discriminates
two
equally
likely
alternaUves
To
select
between
N
equal
choices,
Nbits
=
log2
N
• For
12-‐coin
problem,
Nbits
=
log2
(12)
+
1
=
log2
24
(must
also
disUnguish
light
vs.
heavy)
• InformaUon
provided
in
each
measurement
is
log2
3
(3
posiUons
for
scale:
le^,
right,
balanced)
• For
three
weighings,
Wbits
=
log2
33
=
log2
27
Meets
necessary
condiUon
that
Wbits
>=
Nbits
5
October
2009
19
20. Necessary,
but
not
sufficient
• A
strategy
is
also
necessary
such
that
Wbits
>=
Nbits
(remaining)
is
saUsfied
at
each
step
to
the
soluUon
• Nbits
is
the
same
thing
as
the
entropy
H
H
=
–
Σ
p
log
p
where
p
=
1/N
=
–
Σ
(1/N)
log
(1/N)
=
(Σ
(1/N))
log
N
=
log
N
H
=
log2
N
(in
bits)
5
October
2009
20
21. What
else
do
we
know?
• Physical
priors!
– only
one
coin
is
fake
– astronomical
data
occupy
sparse
phase
space
• FITS
arrays
=
images
(physical
priors)
– of
astrophysical
sources
– taken
through
physical
opUcs
– recorded
by
physical
electronics
– digiUzaUon
is
restricted
by
informaUon
theory
– possessing
a
disUncUve
noise
model
5
October
2009
21
26. ObservaUons
about
observaUons
• The
sequence
of
three
measurements
can
occur
in
any
order
• The
systemaUzaUon
of
the
soluUon
occurs
during
its
definiUon,
not
at
run
Ume
5
October
2009
26
27. Try
it
yourself
hPp://heasarc.gsfc.nasa.gov/fitsio/fpack
hPp://www.mapsofconsciousness.com/12coins
5
October
2009
27