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Dario Izzo

Optimal Control Probem in the CR3BP solved!!! - 7 views

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    This guy solved a problem many people are trying to solve!!! The optimal control problem for the three body problem (restricted, circular) can be solved using continuation of the secondary gravity parameter and some clever adaptation of the boundary conditions!! His presentation was an eye opener ... making the work of many pretty useless now :)
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    Riemann hypothesis should be next... Which paper on the linked website is this exactly?
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    hmmm, last year at the AIAA conference in Toronto I presented a continuation approach to design a DRO (three-body problem). Nothing new here unfortunately. I know the work of Caillau, although interesting what is presented was solved 10 years ago by others. The interest of his work is not in the applications (CR3BP), but in the research of particular regularity conditions that unfortunately make the problem limited practically. Look also at the work of Mingotti, Russel, Topputo and other for the (C)RTBP. Smart-One inspired a bunch of researchers :)
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    Topputo and some of the others 'inspired' researchers you mention are actually here at the conference and they are all quite depressed :) Caillau really solves the problem: as a one single phase transfer, no tricks, no misconvergence, in general and using none of the usual cheats. What was produced so far by other were only local solutions valid for the particular case considered. In any case I will give him your paper, so that he knows he is working on already solved stuff :)
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    Answer to Marek: the paper you may look at is: Discrete and differential homotopy in circular restricted three-body control
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    Ah! with one single phase and a first order method then it is amazing (but it is still just the very particular CRTBP case). The trick is however the homotopy map he selected! Why this one? Any conjugate point? Did I misunderstood the title ? I solved in one phase with second order methods for the less restrictive problem RTBP or simply 3-body... but as a strict answer to your title the problem has been solved before. Nota: In "Russell, R. P., "Primer Vector Theory Applied to Global Low-Thrust Trade Studies," JGCD, Vol. 30, No. 2", he does solve the RTBP with a first order method in one phase.
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    I think what is interesting is not what he solved, but how he solved the problem. But, are means more important than end ... I dunno
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    I also loved his method, and it looked to me that is far more general than the CRTBP. As for the title of this post, OK maybe it is an exageration as it suggests that no solution was ever given before, on the other end, as Marek would say "come on guys!!!!!"
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    The generality has to be checked. Don't you think his choice of mapping is too specific? he doesn't really demonstrate it works better than other. In addition, the minimum time choice make the problem very regular (i guess you've experienced that solving min time is much easier than mass max, optimality-wise). There is still a long way before maximum mass+RTBP, Topputo et al should be re-assured :p Did you give him my paper, he may find it interesting since I mention the homotopy on mu but for max mass:)
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    Joris, that is the point I was excited abut, at the conference HE DID present solutions to the maximum mass problem!! One phase, from LEO to an orbit around the moon .. amazing :) You will find his presentation on line.... (according to the organizers) I gave him the reference to you paper anyway, but no pdf though as you did not upload it on our web pages and I could not find it in the web. So I gave him some bibliography I had with be from the russians, and from Russell, Petropoulos and Howell, As far as I know these are the only ones that can hope to compete with this guy!!
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    for info only, my phd, in one phase: http://pdf.aiaa.org/preview/CDReadyMAST08_1856/PV2008_7363.pdf I prefered Mars than the dead rock Moon though!
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    If you send me the pdf I can give it to the guy .. the link you gave contains only the first page ... (I have no access till monday to the AIAA thingy)
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    this is why I like this Diigo thingy so much more than delicious ...
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    What do you mean by this comment, Leopold? ;-) Jokes apart: I am following the Diigo thingy with Google Reader (rss). Obviously, I am getting the new postings. But if someone later on adds a comment to a post, then I can miss it, because the rss doesn't get updated. Not that it's a big problem, but do you guys have a better solution for this? How are you following these comments? (I know that if you have commented an entry, then you get the later updates in email.) (For example, in google reader I can see only the first 5 comments in this entry.)
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    I like when there are discussions evolving around entries
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    and on your problem with the RSS Tamas: its the same for me, you get the comments only for entries that you have posted or that you have commented on ...
darioizzo2

(PDF) Comparison study of MPM and SPH in modeling hypervelocity impact problems - 1 views

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    Material point method is an efficient and promising method for simulating complex stuff. Not used much in Astro, a lot in gaming, cartoons etc.... Worth having a look in comparison with SPH in simulation (for example those connected to the HERAS mission)
jaihobah

Breakthrough method means CRISPR just got a lot more relevant to human health - 0 views

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    "scientists at Harvard University say they've modified the CRISPR method so it can be used to effectively reverse mutations involving changes in one letter of the genetic code. That's important because two-thirds of genetic illness in humans involve mutations where there's a change in a single letter."
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    "Efficient introduction of specific homozygous and heterozygous mutations using CRISPR/Cas9" http://www.nature.com/nature/journal/vaop/ncurrent/full/nature17664.html?WT.ec_id=NATURE-20160428&spMailingID=51249830&spUserID=MTEzODM0NjYzMzgS1&spJobID=903461217&spReportId=OTAzNDYxMjE3S0 As posted here previously, the number and importance of CRISPR is growing steadily, but still plenty of work to make it a reliable tool. Maybe, next work for the Molecular Engineering RF?
ESA ACT

Digital holographic microscopy reveals prey-induced changes in swimming behavior of pre... - 0 views

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    The study doesn't seem relevant to us - but the name of the method is just marvellous!
ESA ACT

Colours light up brain structure : Nature News - 0 views

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    A new and amazing method for neuron staining.
ESA ACT

The Sociocratic Method - 0 views

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    A method on how to run businesses based on consent (not consensus).
Thijs Versloot

Spotting East African Mammals in Open Savannah from Space - 1 views

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    A hybrid image classification method was employed for this specific purpose by incorporating the advantages of both pixel-based and object-based image classification approaches. This was performed in two steps: firstly, a pixel-based image classification method, i.e., artificial neural network was applied to classify potential targets with similar spectral reflectance at pixel level; and then an object-based image classification method was used to further differentiate animal targets from the surrounding landscapes through the applications of expert knowledge. As a result, the large animals in two pilot study areas were successfully detected with an average count error of 8.2%, omission error of 6.6% and commission error of 13.7%. The results of the study show for the first time that it is feasible to perform automated detection and counting of large wild animals in open savannahs from space
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    And Paul, it includes neural networks!
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    I kept telling you guys but you just laughed and laughed :))
jcunha

New method uses heat flow to levitate variety of objects - 1 views

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    Normally we associate levitation of objects to superconducting materials. Here a new technique is shown where levitation of a whole new range of materials is shown. "The large temperature gradient leads to a force that balances gravity and results in stable levitation," said Fung, the study's lead author. "We managed to quantify the thermophoretic force and found reasonable agreement with what is predicted by theory. This will allow us to explore the possibilities of levitating different types of objects." Paper at http://aip.scitation.org/doi/10.1063/1.4974489 New microgravity experiments possibility?
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    not really I fear .... "Typical sizes of the trapped particles are between 10 μm and 1 mm at a pressure between 1 and 10 Torr. The trapping stability is provided radially by the increasing temperature field and vertically by the transition from the free molecule to hydrodynamic behavior of thermophoresis as the particles ascend."
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    Might still be OK micro to mm sized experiments. The technique seems to be reliable and cheap enough to compete with other types of microgravity approaches - more research needed to define boundaries of course.
santecarloni

Laser gyroscope measures the Earth's 'wobble' - physicsworld.com - 2 views

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    An international team of researchers have developed a new type of gyroscope that is the first to measure the "wobble" in the rotational axis of the Earth from a ground-based laboratory. Astronomers normally track this wobble by continuously monitoring the position of distant objects, such as quasars. But this new method will provide a much simpler and cheaper alternative to these large-scale astronomical readings, the scientists claim.
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    is this of any use for spacecraft?
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    mmm it's like saying that you can replace satellite tracking by accelerometers on-board satellites... for Leo: you'd better put an atomic gyro on a spacecraft these laser gyro are huge !
Tom Gheysens

Programmable glue made of DNA directs tiny gel bricks to self-assemble | KurzweilAI - 3 views

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    New method could help to reconnect injured organs or build functional human tissues from the ground up
Dario Izzo

Climate scientists told to 'cover up' the fact that the Earth's temperature hasn't rise... - 5 views

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    This is becoming a mess :)
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    I would avoid reading climate science from political journals, for a less selective / dramatic picture :-) . Here is a good start: http://www.realclimate.org/ And an article on why climate understanding should be approached hierarcically, (that is not the way done in the IPCC), a view with insight, 8 years ago: http://www.princeton.edu/aos/people/graduate_students/hill/files/held2005.pdf
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    True, but fundings are allocated to climate modelling 'science' on the basis of political decisions, not solid and boring scientific truisms such as 'all models are wrong'. The reason so many people got trained on this area in the past years is that resources were allocated to climate science on the basis of the dramatic picture depicted by some scientists when it was indeed convenient for them to be dramatic.
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    I see your point, and I agree that funding was also promoted through the energy players and their political influence. A coincident parallel interest which is irrelevant to the fact that the question remains vital. How do we affect climate and how does it respond. Huge complex system to analyse which responds in various time scales which could obscure the trend. What if we made a conceptual parallelism with the L Ácquila case : Is the scientific method guilty or the interpretation of uncertainty in terms of societal mobilization? Should we leave the humanitarian aspect outside any scientific activity?
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    I do not think there is anyone arguing that the question is not interesting and complex. The debate, instead, addresses the predictive value of the models produced so far. Are they good enough to be used outside of the scientific process aimed at improving them? Or should one wait for "the scientific method" to bring forth substantial improvements to the current understanding and only then start using its results? One can take both stand points, but some recent developments will bring many towards the second approach.
jmlloren

Why starting from differential equations for computational physics? - 1 views

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    "The computational methods currently used in physics are based on the discretization of differential equations. This is because the computer can only perform algebraic operations. The purpose of this paper is to critically review this practice, showing how to obtain a purely algebraic formulation of physical laws starting directly from experimental measurements."
Marcus Maertens

New Method Confirms Humans and Neandertals Interbred - 0 views

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    Looks like the genetic evidence for the interbreding of homo sapiens and homo neanderthalensis becomes significant.
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    "Humans and Neanderthals interbred" - isn't that a bit weird since we call the result of the interbreeding "Humans" as well? This is a bit like saying "Ligers and Tigers interbred".
Isabelle Dicaire

Virtual Reality Meetings Are the New Awkward Teleconference | Motherboard - 1 views

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    Research on new working methods? - another interesting application of the Oculus!
jcunha

New methods to make longer streams of plasma with greater longevity could lead to laser... - 0 views

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    More developments in the laser filamentation community. Makes me wonder again about Christophe's ideas for a space-formed filament as new and efficient microwave waveguide.
Francesco Biscani

BBC News - Study hints at dark matter action - 0 views

shared by Francesco Biscani on 16 Feb 10 - Cached
Ma Ru liked it
  • "We can't rule them out as being a signal but we can't conclude that they are a signal."
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    Gotta love the scientific method :)
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    Have to remember this very useful sentence...
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    haha
santecarloni

Optical measurement of cycle-dependent cell growth - 0 views

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    Researchers developed a new imaging method that can measure cell mass using two beams of light, offering new insight into the much-debated problem of whether cells grow at a constant rate or exponentially. They found that mammalian cells show clear exponential growth only during the G2 phase of the cell cycle. This information has great implications not only for basic biology, but also for diagnostics, drug development and tissue engineering.
LeopoldS

Moodboarding Methods for Web Designers | Fuel Your Creativity - 0 views

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    WOuld this be useful for us. e.g. for the Ariadnet design?
nikolas smyrlakis

ACM award concerning the Complexity of Interactions in Markets, Social Networks, and On... - 0 views

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    "The Complexity of Nash Equilibria,", It also suggests that the Nash equilibrium may not be an accurate prediction of behavior in all situations. Daskalakis's research emphasizes the need for new, computationally meaningful methods for modeling strategic behavior in complex systems such as those encountered in financial markets, online systems, and social networks.
Dario Izzo

The SpaceShaft, a new Space Elevator concept - 0 views

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    Combined method of construction and transportation for access to space of distributed heavyweight cargo and personnel with safe, economical and renewable characteristics.
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