inside this episode control and
optimization . The numerical gymnastics
needed to solve earth and space bound
problems . But first examining social
media to gain a better view of
revolutionary communication .
Social media and social networks have
changed the landscape culturally and
politically the world over . Most
social media platforms were created as
means to strengthen connections among
friends and family , to share
information with like minded
individuals and to advertise products
and services directly to a target
market . But from flash mobs to
political protests , social media also
quickly proved a valuable resource for
mobilization .
The arab spring started with a death in
early january protesters took to the
streets of Tunisia in solidarity with a
young fruit vendor who despairing of
the brutal system under which he lived ,
set himself on fire . It was a death
that gave life to a movement that was
to alter the course of the Middle East
and north africa .
There's no question social media played
a part in arab spring . Just how much
effect did social media have mps .
Researchers sought to answer this
question in mind . All public data on
twitter related to Egypt sort of by
accident . We got access to the twitter
data . I belong to a list serve that
someone had sent out a message that
this twitter data from the arab spring
was available and probably some really
good ideas about how to analyze it . It
was one million tweets and we tried to
see if we could actually do anything
with it . And after quickly breaking
the computer , he finally figured out
how to actually begin to analyze the
data and then we're able to actually
really tease out some really
interesting questions from the data
itself . They generated a user by user
network where a direct tie was drawn
between two users . If one of the users
sent a message to the other or a user
retweeted the message to another , the
initial look at the data and it looked
like what we would call it , either bad
hair day or an exploding death star .
And we had to find ways of drilling
down and teasing out some of the
aspects of it . So we ended up using
some subgroup protection or community
detection algorithms to kind of pull
apart the network . So we could
actually better analyze it . We end up
finding out that just because I ended
up sending out something from one
person and another person sent
something out from that person if that
central node was celebrity , those
other two people , they won't be
talking to each other . But what we end
up seeing when we ended up looking at
those that were around activist
accounts of people that were actually
very much involved in the protests ,
um there might be these key nodes and
they'd be linked to a whole bunch of
other people but the people they're
linked to would be connected to each
other as well . So it was these really
thick spots in the network In the end
this network included
196,670 users .
526,976
ties between them . It was not the
number of connections made , but what
was said and repeated through these
connections . Central activists frame
grievances in ways that brought people
together and possibly help mobilize
them for action . Social movement
theory argues that a number of factors
need to come into place in order for a
social movement to get off the ground
to get people out on the street and
actually motivated to do things . They
need to have enough resources and they
have to have sort of a vulnerable
status quo . But one of the most
important factors is that the
grievances have to be framed in ways
that resonate with the target audience .
And one of the professors here in the
defense analysis department , Glenn
Robinson talks about framing at sort of
the bumper sticker approach to
grievances is that you can , if you can
frame the grievances in short ,
distinct and snappy messages um
then it can it can resonate with the
crowd and you actually get people out
in the streets and so we saw what was
going on with the tweets was not not
obviously all the tweets that were out
there , but in general a lot of these
tweets we hypothesized were motivating
for us for getting these people out in
the streets . One account that was
fairly prominent in Arabic was this
fake hosting mubarak account . And so
it's just a parody account . It's not
real at all , but it was sending up
messages at the same time that hosting
mubarak was addressing the country and
saying things like fool me once shame
on you , fool me twice shame on
everyone else and things about how many
um assassination attempts that he ended
up surviving and he ended up framing
those new mubarak as a bad person , a
bad character . Um and it was able to
effectively it was able to counter
message . Um but the real Hosni mubarak
was saying and it was actually quite
prominent , I mean his message is
actually connected with a lot of
different people engaging social media
users and creating cohesive pockets of
sympathetic groups increased the
likelihood of certain topics to trend
and gain more visibility in the past .
What you often saw was social movements
was that the media would be the
gatekeeper . So if you want to actually
have the wider population access your
message , you need to sell it to the
media who will then show it to everyone
else in in the country or in the state
or in the world . And now what you're
actually seeing a lot of times is that
the media itself is using social media
in order to figure out what's going on
in what they should be covering . So
the relationship between the media and
the social movements has changed
someone with the use of these
technologies where you can access
hundreds of millions of people . This
video is one of hundreds , possibly
thousands uploaded to social media
websites like Youtube in the past few
weeks , purporting to show government
attacks on the baba AMR district of
Homs . In the absence of many foreign
journalists , social media has become
one of the key tools for telling the
outside world what's happening .
One of the things that we have been
doing lately was , I mean , expanding
this research to looking at what's
going on in Syria , which is a
different focus because a lot of times
we were looking at trying to understand
how these different groups were kind of
popping up . So you had the Free Syrian
Army , you had the Jabal al Nusra , you
have now uh the Islamic state of Iraq
and uh Sham . Uh so all these different
groups have been popping out and we've
been actually able to , we just
actually had a report come out um
myself and Greg Freeman and other
research associate , um the Office of
the Secretary of Defense rapid reaction
Technology office sponsored us to try
to see how these different groups were
using social media . They've been
fairly prolific on their social media
usage . The goals are different , but
you now have frames and counter frames
going on . So you have either ISIS or
ISil are good people or you have other
people calling them Daesh , which is uh
Arabic , it's the Arabic version of
their acronym and those people are
typically saying things negative about
um ISIS or ISIL and so you have these
many , many different frames . You have
the kurdish opinion on things . You
have the free Syrian army opinion of
things . You have the pro assad opinion
on what's going on . And so trying to
look at these different social media
presence . It's really by using like
the pattern of ties , you can actually
start pulling apart these different
groups and kind of being able to better
understand what's going on
when we return control and optimization
takes us to space and beyond .
It's been 60 years since we started
traveling to space , almost 45 years
since we first walked on the moon and
more than 15 years since the
international space station has been in
orbit . So it's hard not to have that
been there done that attitude or even
to have sticker shock when looking at
the price tag of planned future
missions . Thankfully scientists ,
especially those that NPS have been
working hard to find new ways to
improve current mission strategies ,
essentially getting the most bang for
your buck . This next segment is the
first of two parts on control and
optimization . Control and optimization
is basically related to trying to find
ways of operating a given system more
effectively or more efficiently
depending on the system you're dealing
with the results that you get when you
apply some of these ideas can be just
breathtaking are very , very striking
and examples of optimal control . You
really can find them everywhere . You
can think about U A . V . S attitude
control of the spacecraft or satellite
going to mars or going to the moon . I
can take one path and it may cost me a
certain amount of fuel or take a
certain amount of time or I can take
another one which may cost me less fuel
or less time . If you were to apply the
standard ideas on how to maneuver that
system it may tell you we just can't
get that information . So optimal
control is really all about the idea of
finding the best path to take which
will minimize the cost and maximize the
objective that you're trying to realize .
Coming up 48 seconds mark 48 seconds
max q maximum dynamic pressure in the
vehicle . Pseudo spectral optimal
control is actually a mathematical and
computational theory . So it's one of
those , it's a really neat um
combination of a bunch of ideas from
from various areas that was developed
by Professor Isaac Michael Ross and Dr .
Fariba Peru in around the year 2000 or
so . And it really has given us the
opportunity to solve a classic problems
that before this idea really were not
solvable . Maybe the best way to think
about pseudo spectral optimal control
is to think about your iphone pseudo
spectral optimal control theory is like
a generic tool for solving optimal
control problems . Just like your
iphone is a kind of platform that you
can load different kinds of apps onto .
So if pseudo spectral optimal control
is the iphone , the apps that we
integrate with this um optimal control
framework are the different kinds of
problems that we want to solve . So one
of the neat things about pseudo
spectral optimal control is that we
actually have had the opportunity to
take the theory from the laboratory and
the computer and actually implement it
In practice . So way back in 2006 , we
used pseudo spectral optimal control
techniques to find a way to maneuver
the international space station through
very large angles . So we wanted to
rotate the whole thing 90 or 180°
without using thrusters . The first
time we've been doing a major maneuver
with normally to do this kind of
maneuver , we have to fire off the
thrusters because they have the power
that we need to perform this large
angle rotation . It's just a little
white knuckle for
failing the station . That's
essentially what they're doing using
pseudo spectral optimal control
techniques . What we were able to
figure out is how to use the gravity
torque that is part of the space
environment , which is existing on
orbit in a way that we could actually
use those torques to help us maneuver
the station and in doing so we could
achieve these large angle maneuvers
without the need to fire the thrusters .
Okay , the maneuver is over everybody's
real happy back here , you know , now
they're gonna want to do it all the
time . So because we're able to do this
each time , we need to do a large angle
slough like this or a large angle
maneuver , we could save upwards of $1
million dollars in fuel costs and
that's a pretty big deal .
Just to give you a kind of different
perspective on how it works . You can
think about sailing a boat into the
wind and intuitively if the wind is
coming at you , you would think that
it's impossible to propel yourself
forward . But it turns out that if you
figure out how to steer that boat
properly , you actually can collect
some of the force of the wind and use
that to propel yourself forward . So
it's really kind of the same concept
that was employed on the international
space station , but instead of using
the wind , we're using the gravity
torque that's available in the space
environment . A few years later we
applied the same set of tools to solve
what we call the shortest time maneuver
problem for the Nasa space telescope
called Trace . The idea there is not to
say fuel , but to figure out how we can
re point the telescope as quickly as
possible kind of on orbit demonstration
of how many images can we collect in a
given amount of time . So for trace
were able to demonstrate for the first
time how we're able to solve the
shortest time maneuvers and actually
implement them on a real system , a
real system that's actually already
been on orbit for a number of years .
So up until around the time suit of
spectral techniques have been developed .
People knew about this idea . There was
some papers written in the early 90s
and a bunch of simulation studies that
have been done to see what kind of
benefit you can get . But the tools
were just not at the stage , they
needed to be to attack and solve a
problem for a real system . Real system
has all kinds of intricate bells and
whistles that we need to consider and
when we try to use some of the old
techniques for solving these problems
for that purpose , they fall flat on
their face . So pseudo spectral optimal
control ideas really opened the door to
being able to take some of these
concepts that people have been toying
around with and thinking that they
might work if only we had the right
tools to solve the problem and actually
get those from the drawing board and
implemented on practice after the break .
A crippled space telescope finds new
life and how optimal control can be
applied to public health .
Nasa's kepler mission has confirmed the
discovery of the first Earth sized
planets outside our solar system
orbiting a sun like star , three super
Earth sized planets orbiting in the
habitable zone of their stars . The
first system of multiple planets
orbiting a pair of stars or as
astronomers call it a circum binary
system . The kepler spacecraft is
actually a really neat spacecraft in
that it has very , very stringent
requirements . What kepler is is
actually a telescope that Nasa put on
orbit to find planets . And it turns
out that finding a planet requires you
to point the telescope at a certain
section of the sky very accurately .
And the kicker is that you have to be
able to maintain this accuracy for very ,
very long periods of time . The idea
being that the method , which is used
to detect the planets sort of , is
driving this long time requirement of
being able to point in a particular
spot .
So Kepler was designed with all of the
right hardware to be able to do this .
But in the spring of 2013 , the
second of four of Kepler's reaction
wheels failed and so that effectively
crippled the spacecraft . The envy that
kepler's in there is a strong torque
that is being produced on the vehicle
that comes from the sense and the sun's
emitting all these photons and whatnot
and those actually can press against
the body of the spacecraft and cause it
to rotate around . And so one of the
key challenges for kepler was given
that we only have two wheels . How do
we control those two wheels in such a
way that we can minimize the drift
that's induced by the solar pressure .
And so the idea behind the different
control concepts that was developed is
essentially to use the reaction wheels
in a very special way that helps reduce
the effect of that solar pressure as
much as possible and for as long as
possible . Some of the things that
we're working with Nasa now in terms of
supporting the kepler mission is to be
able to look at different ways . We can
apply optimal control ideas to help
make that mission a little bit more
efficient in terms of fuel usage . The
idea here is that kepler's on orbit ,
we have nail a control system in place
to be able to perform planet hunting
types of missions and how long will the
remaining fuel on board last us ?
Basically . What we'd like to be able
to do is minimize or reduce as much as
possible the consumption of fuel for
the routine day to day operations of
the spacecraft with the idea being that
the more fuel we can conserve now , the
longer we can keep that spacecraft
producing scientific data
in frigid , silent darkness , a million
miles from earth , an immense space
telescope scans the heavens
shielded from the sun , earth and moon ,
It pursues profound mysteries . How do
planets form ? How did matter come
together to make the first stars and
Galaxies where among the stars might we
find life astronomers
worldwide will seek answers Using the
unprecedented capabilities of the web
space telescope
James webb space telescope as you know ,
is a very , very expensive piece of
scientific instrumentation . And what
we'd like to be able to do is get the
most bang for a buck from that system .
And so one of the ideas that would be
very cool to explore and possibly bring
to some level of fruition Is the
ability to reduce the amount of time it
takes to have the James Webb re point
to a new scientific target . One of the
things that we did sort of back of the
envelope computations and we kind of
figured that if we can shave off even
1% of each of the James Webb sloughs
as we perform the mission , that could
amount to more than $10 million dollars
of additional scientific data that we
can collect . That's a pretty big deal .
Slough is actually just our scientific
jargon for a maneuver that takes us
from pointing in one direction to
another . So if we're pointing at Star
A . And we want to point the spacecraft
at Star B . We call a slew the maneuver
between those two points . Now , one of
the things we've observed in working
with different systems is that 1% is
very easy to get . We usually get 2030 ,
sometimes even 50% improvement in
performance . So if you map that The
smallest number 20% uh to that $10
million 1% savings , you can see that
implementing some of these new concepts
really will go a long way to helping us
maximize the benefit we get from some
of these new systems .
There's also a number of different
fields that can use optimal control
techniques in order to further or
advance what they're able to do . And
one of those fields , for example , is
the medical field , um , looking at
disease control and how to curb the
spreading of infectious diseases . The
idea of posing that problem as an
optimal control problem is not new .
People know that you can do that . The
problem is that some of these other
fields outside of aerospace do not have ,
in my opinion as well , developed a set
of tools as some of the tools that we
have available to us to solve these
different kinds of aerospace problems .
And so what that really forces the
researchers and some of these different
areas to do is simplify the problems
that they're solving because those are
the only kinds of problems that they
feel they cancel with the tools that
they have . So I'm hoping that at some
point , some of these other areas will
begin to see all of the neat things
that we can do in aerospace and
possibly adopt or adapt some of the
tools that we have developed and bring
them into these other areas . And the
reason why I think this is gonna be
very important and lead to some very
cool results is because it allows those
researchers to stop basically saying
what problem can I solve and start
asking the question what problems
should I solve ? And hopefully , those
problems will get closer and closer to
reality , because the researchers there
now know that they have the tools that
they need to be able to solve this .