NASA is a whole lot more than just the space program.. You'd like to see NASA's budget cut, but don't realize, that those cuts WON'T affect the space program.. The space program has been positioned as the most visible program at NASA, and they'll keep the funding for that going.. Cuts will affect the fundamental research programs. The groups who are trying to figure out how to reduce accoustic emissions (noise pollution) from subsonic jet flows, the crowd trying to pin down key parameters in hydrodynamic instabilities which affect our ability to lay down thin uniform films in high speed manufacturing processes (think photographic, or TFTs), etc...
Huh?.. How is SCSI or EIDE proprietary? I've had half a dozen PMacs over the last few years and not one of them required a proprietary HDD.. Now, Apple may not supply drivers with their hard disk tools for every drive out there, but all you need to do is grab a copy of FWB Toolkit (the personal edition ships for free with drives from a number of vendors) and you're golden..
So if we're not talking about the HDD, you must be talking about the 72 pin SIMMS, or the 168 pin DIMMS, and more recently PC100 or 133 SDRAM.. Nope, wait those aren't ay different than the RAM shipped for PCs.. Maybe it's the processor.. Who cares, the standard MacOS supports that, and so do netBSD, AUX, mkLinux, LinuxPPC, etc..
Re:...but will it keep up with the upgrades?
on
Laser-equipped 747
·
· Score: 1
I read a couple technical reports regarding the Air-Borne Laser project, and as I understand it, the missile must be identified and hit during the first few seconds of its launch. The longer it takes to identify, target, and hit the missile the less chance there is for success. The ABL structurally weakens the missile, and if lucky that weakened structure will crumple during launch. The biggest problem with the ABL program is that there's data that suggests that many missiles will continue to fly even with a severly damaged structure. The solid fuel boosters on the Challenger are the most notable example of this. During that accident the solid fuel damaged solid fuel booster burnt a hole in the external fuel tank causing the explosion, and then separated from the tank during the explosion, and continued to fly for an execeptional distance before exhausting their fuel. The point is, that even with an exhaust plume firing out the side of the rocket, melting the structure, it continued to fly a noticable distance.. So maybe we hit a missile with this laser. Big deal, if the tank isn't hit and the missile isn't completely destroyed, it may end up striking a foreign town rather than the aircraft it had targeted.
Re:...but will it keep up with the upgrades?
on
Laser-equipped 747
·
· Score: 1
There are much better ways to do this. For an example, take a look at the upgrade the Air Force will be making on the next group of C-17's.. They will all have an open loop flow control system in the jet nozzle to fan the thermal exhaust plume. This is a system that uses pulsed air to excite an instability in the structure of the jet, and results in enhanced mixing (at the expensive of increased accoustic emissions). The same technique should be possible on missiles.
I would almost rather see Apple throw itself behind HURD than cause more fragmentation amongst the BSDs.
Mac OS X does not use the BSD kernel. It uses the Mach kernel, just like HURD I believe..
As for the Linux replacing BSD question, forget it.. Mac OS X is an upgraded version of the NeXT OS, and the developers that Apple has working on this project are comfortable with the BSD layer. I personally run OS X PB on a B&W G3 and am constantly amazed. The interface is still a little slower than OS 9 and earlier, but the stabilty si very very nice. (It's funny, I can remember the last time my PowerBook crashed running OS 8.6.)
you are assuming that all gene are created equal. The likely metaphor might be a little like blue-print of a house. what happen if we change something randomly? will the house collapse? hot water pipe explode? or just the door handle kinda get crooked. plus, the gene map is pretty robust, mother-nature is no full in creating live. She device way to handle copying error.
Well.. I certainly agree that Mother Natue is pretty bright, and anyone who doesn't see that is pretty crazy.. But my point is that you're thinking about things in a VERY linear way.. A change in one gene has one specific quantifable effect. That maybe the way the genome works, but I'd be pretty surprised.. I prefer to think of it like I do with turbulent flows.. The genome is a set of initial conditions (input parameters) and the equations that govern the flow, or life in this case, are nonlinear and extremely sensitive to initial conditions. Small changes in the initial conditions can often be used to make enormous changes in the mean flow.. Don't believe me? Go take a look at some of the literature on "Turbulent Flow Control", where an excitation consisting of 0.001% of the mean momentum of the flow can occasionally be used to persuade a normally separating flows to reattach..
Let's think about this as a large software project.. You change a couple subroutines very subtly. Those changes may have little or no affect on the parameters you're monitoring, BUT what about the parameters that fall outside your view.. This may not be a huge problem when we're writing and compiling code for chips we have the specs to, but what happens when you're trying to code a "processor" that has an unknown set of parameters?.. Right now there are effictively an infinite number of possible solutions to the human genome. So, we have no equations and a whole bunch of unknowns!!!
I'm not entirely opposed to the idea of trying to reverse engineer the human genome (basically we're looking at the assembly for a processor we know nothing about, right?).. My concern is that we can't keep track of all the variables as we tweek the gene sequence.. Attempting to classify the internals of this black box is not as easy as passing white noise to it, and watching a few output ports.. How far can gene 2.2.18 be tweeked before the system becomes unstable?
Mother Nature has a great mechanism for eliminating copying errors.. Typically they're referred to as diseases, or mutations, and those errors usually weed out copies that are "weaker" in one form or another. That's sort of the premise of evolution as I understand it..
This is an honest question.. If there are thousands, millions, or billions of genes in an organsim, and I decide to make a subtle change to one of those genes how can we predict the effects of that change on the organism as a whole??
Let's simplify the problem a bit.. Let's say there are 10 genes in the organism of interest. We have no equation, or set of equations, to govern the response of the system to a change.. So the best option we have requires some sort of empirical approach. So I gather up a large subset of the population, examine each, and note their differences. Then I'd compute something like a two-point correlation tensor.. So if I have 10 genes and, coincidently I find 10 differences, that's a 10x10 matrix of relations between the "causes" and "effects". So that's not bad, right?
Wrong.. This is a non-linear system, and a subtle change in one gene may have an enormous impact on a handful of genes. Then another subtle change in a second gene, may negate the effects of the first change.. I'm curious what sort of training the geneticists working on these sequencing problems have with non-linear systems?
This is not an attack: I'm curious.. I've spent a lot of time over the last few years trying to get a handle on the inner workings of simple turbulent flows, and even with a set of governing equations to guide my efforts, the problem of predicting how subtle changes will affect my flow is non-trivial!.
I always get a chuckle when I read the predominantly Linux using readers of SlashDot badmouth the MacOS and/or Mac Users.. With that said, you may want to take a look at the general Mac OS X user forum at osx.macnn.com. Of particular relevence to this discussion are:
The MacOS isn't perfect, and neither is OS X.. A number of the reader submissions to the "customizing the interface" are questions and/or suggestions regarding turning off transparency, drop shadows, and making the windows rectangular.. These are adjustments that require a bit of work right now, but improve the effective speed of the interface. And you're right in claiming that they're not alterations that Apple is going to promote people making. But a handful of theme construction tools are already being put together, and the effects can be turned off if you want it bad enough..
I don't think so!! Six degrees of freedom would mean x,y,z translation, and roll, pitch and yaw moments.. If you've got a camera in each lamp post, you don't need any of the translation degrees. You just need to stitch the images (acquired simultaneously) together from each camera, and then pass them to a QuickTime VR viewer so the operator could float around the scene.. Hint: imagine shots such as those in the Matrix..
Of course, this is a non-issue with Macs, as Apples upgrade policy has always been "Buy a new one"
I'm sitting here in front of a Powerbook G3/400, while my B&W G3 500 (upgraded from 300 for $30 after I sold the g3/300 on eBay) serves files to a cluster of linux boxes via NFS from MOSX.. I haven't used a floppy disk for anything other than maintaining a few garbage Gateway and Dell machines for the last 4 years..
Your BIOS comment shows your ignorance. Macs, like Sun boxes I believe, use openFirmware rather than BIOS, and upgrading the OF is typically trivial (patches are typically shipped as small executables, run the executable, reboot the machine and you're done).
Here's a neat trick you can ask a Mac user to show you some time.. Launch the energy saver control panel under OS 8+, set the start up and shutdown/sleep schedule. Close the control panel. The machine will alter a few settings in OF. If you open the system disk control panel and click on the MOSX drive, before shutting down the machine. The OF will still watch the clock and fire up selected OS, even if you've told it to launch MOSX rather than OS 8+.. I've never seen a PC start-up and shutdown on its own, sure they can reboot, but I'm talking about effectively hitting the power button.
The dimples on golf balls act to trip the boundary layer from laminar to turbulent. This transition pushes the point of boundary layer separation to the trailing side of the ball, which reduces the pressure drag on the ball. Note: the transition from laminar to turbulent flow is probably the result of the dimples exciting instabilities in the BL
Now, as for flow control techniques for drag reduction and separation control, this is currently the most active area of fluid dynamics research. I just returned from the AIAA meeting in Denver and participated in a poster session where Boeing/Pratt & Whitney were showing off their C-17 project. Using pulsed jets of air to mix out the jet shear layer more rapidly. United Technologies Research Center had a poster, as well as a nice, talk discussing dynamic flow separation control on helicopter rotor blades. A group from UCDavis was showing off some MEMS MicroFlaps that they are investigating as potential replacments for the large overweight and extremely complex high lift devices found on most large aircraft. Then there was a group at Notre Dame, investigating Phased Plasma actuators (think surface mounted glow plugs) as a means of controlling high speed flows.
The passive techniques used in golf balls is also a large area of interest. I have spent a while talking to some folks from Princeton who've been making measurments for Callaway, and attempting to improve the flight characteristic of their balls. Someone mentioned vortex generators, and feel compelled to mention that NASA Langley, as well as a number of universities, has been playing with MicroVGs for quite a while now. There is also a group of folks using dynamic VGs and fluidic VGs (typically referred to as Synthetic Jets) in the research community.
The biggest problems with the application of flow control techniques to practical problems are size, weight, power requirements, and robustness. I could probably reduce the drag on my Honda appreciably within a couple weeks, using some of the stuff I play with in my lab. BUT the overall fuel efficiency may not make improve noticably due to the power requirements of active controll and passive techniques are typically tuned to a specific set of flow conditions. Then there's the car wash issue...
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NASA is a whole lot more than just the space program.. You'd like to see NASA's budget cut, but don't realize, that those cuts WON'T affect the space program.. The space program has been positioned as the most visible program at NASA, and they'll keep the funding for that going.. Cuts will affect the fundamental research programs. The groups who are trying to figure out how to reduce accoustic emissions (noise pollution) from subsonic jet flows, the crowd trying to pin down key parameters in hydrodynamic instabilities which affect our ability to lay down thin uniform films in high speed manufacturing processes (think photographic, or TFTs), etc...
Huh?.. How is SCSI or EIDE proprietary? I've had half a dozen PMacs over the last few years and not one of them required a proprietary HDD.. Now, Apple may not supply drivers with their hard disk tools for every drive out there, but all you need to do is grab a copy of FWB Toolkit (the personal edition ships for free with drives from a number of vendors) and you're golden..
So if we're not talking about the HDD, you must be talking about the 72 pin SIMMS, or the 168 pin DIMMS, and more recently PC100 or 133 SDRAM.. Nope, wait those aren't ay different than the RAM shipped for PCs.. Maybe it's the processor.. Who cares, the standard MacOS supports that, and so do netBSD, AUX, mkLinux, LinuxPPC, etc..
I read a couple technical reports regarding the Air-Borne Laser project, and as I understand it, the missile must be identified and hit during the first few seconds of its launch. The longer it takes to identify, target, and hit the missile the less chance there is for success. The ABL structurally weakens the missile, and if lucky that weakened structure will crumple during launch. The biggest problem with the ABL program is that there's data that suggests that many missiles will continue to fly even with a severly damaged structure. The solid fuel boosters on the Challenger are the most notable example of this. During that accident the solid fuel damaged solid fuel booster burnt a hole in the external fuel tank causing the explosion, and then separated from the tank during the explosion, and continued to fly for an execeptional distance before exhausting their fuel. The point is, that even with an exhaust plume firing out the side of the rocket, melting the structure, it continued to fly a noticable distance.. So maybe we hit a missile with this laser. Big deal, if the tank isn't hit and the missile isn't completely destroyed, it may end up striking a foreign town rather than the aircraft it had targeted.
There are much better ways to do this. For an example, take a look at the upgrade the Air Force will be making on the next group of C-17's.. They will all have an open loop flow control system in the jet nozzle to fan the thermal exhaust plume. This is a system that uses pulsed air to excite an instability in the structure of the jet, and results in enhanced mixing (at the expensive of increased accoustic emissions). The same technique should be possible on missiles.
I would almost rather see Apple throw itself behind HURD than cause more fragmentation amongst the BSDs.
Mac OS X does not use the BSD kernel. It uses the Mach kernel, just like HURD I believe..
As for the Linux replacing BSD question, forget it.. Mac OS X is an upgraded version of the NeXT OS, and the developers that Apple has working on this project are comfortable with the BSD layer. I personally run OS X PB on a B&W G3 and am constantly amazed. The interface is still a little slower than OS 9 and earlier, but the stabilty si very very nice. (It's funny, I can remember the last time my PowerBook crashed running OS 8.6.)
you are assuming that all gene are created equal. The likely metaphor might be a little like blue-print of a house. what happen if we change something randomly? will the house collapse? hot water pipe explode? or just the door handle kinda get crooked. plus, the gene map is pretty robust, mother-nature is no full in creating live. She device way to handle copying error.
Well.. I certainly agree that Mother Natue is pretty bright, and anyone who doesn't see that is pretty crazy.. But my point is that you're thinking about things in a VERY linear way.. A change in one gene has one specific quantifable effect. That maybe the way the genome works, but I'd be pretty surprised.. I prefer to think of it like I do with turbulent flows.. The genome is a set of initial conditions (input parameters) and the equations that govern the flow, or life in this case, are nonlinear and extremely sensitive to initial conditions. Small changes in the initial conditions can often be used to make enormous changes in the mean flow.. Don't believe me? Go take a look at some of the literature on "Turbulent Flow Control", where an excitation consisting of 0.001% of the mean momentum of the flow can occasionally be used to persuade a normally separating flows to reattach..
Let's think about this as a large software project.. You change a couple subroutines very subtly. Those changes may have little or no affect on the parameters you're monitoring, BUT what about the parameters that fall outside your view.. This may not be a huge problem when we're writing and compiling code for chips we have the specs to, but what happens when you're trying to code a "processor" that has an unknown set of parameters?.. Right now there are effictively an infinite number of possible solutions to the human genome. So, we have no equations and a whole bunch of unknowns!!!
I'm not entirely opposed to the idea of trying to reverse engineer the human genome (basically we're looking at the assembly for a processor we know nothing about, right?).. My concern is that we can't keep track of all the variables as we tweek the gene sequence.. Attempting to classify the internals of this black box is not as easy as passing white noise to it, and watching a few output ports.. How far can gene 2.2.18 be tweeked before the system becomes unstable?
Mother Nature has a great mechanism for eliminating copying errors.. Typically they're referred to as diseases, or mutations, and those errors usually weed out copies that are "weaker" in one form or another. That's sort of the premise of evolution as I understand it..
This is an honest question.. If there are thousands, millions, or billions of genes in an organsim, and I decide to make a subtle change to one of those genes how can we predict the effects of that change on the organism as a whole??
Let's simplify the problem a bit.. Let's say there are 10 genes in the organism of interest. We have no equation, or set of equations, to govern the response of the system to a change.. So the best option we have requires some sort of empirical approach. So I gather up a large subset of the population, examine each, and note their differences. Then I'd compute something like a two-point correlation tensor.. So if I have 10 genes and, coincidently I find 10 differences, that's a 10x10 matrix of relations between the "causes" and "effects". So that's not bad, right?
Wrong.. This is a non-linear system, and a subtle change in one gene may have an enormous impact on a handful of genes. Then another subtle change in a second gene, may negate the effects of the first change.. I'm curious what sort of training the geneticists working on these sequencing problems have with non-linear systems?
This is not an attack: I'm curious.. I've spent a lot of time over the last few years trying to get a handle on the inner workings of simple turbulent flows, and even with a set of governing equations to guide my efforts, the problem of predicting how subtle changes will affect my flow is non-trivial!.
I always get a chuckle when I read the predominantly Linux using readers of SlashDot badmouth the MacOS and/or Mac Users.. With that said, you may want to take a look at the general Mac OS X user forum at osx.macnn.com. Of particular relevence to this discussion are:
The MacOS isn't perfect, and neither is OS X.. A number of the reader submissions to the "customizing the interface" are questions and/or suggestions regarding turning off transparency, drop shadows, and making the windows rectangular.. These are adjustments that require a bit of work right now, but improve the effective speed of the interface. And you're right in claiming that they're not alterations that Apple is going to promote people making. But a handful of theme construction tools are already being put together, and the effects can be turned off if you want it bad enough..
... In a camera mounted in a lamp post?
I don't think so!! Six degrees of freedom would mean x,y,z translation, and roll, pitch and yaw moments.. If you've got a camera in each lamp post, you don't need any of the translation degrees. You just need to stitch the images (acquired simultaneously) together from each camera, and then pass them to a QuickTime VR viewer so the operator could float around the scene.. Hint: imagine shots such as those in the Matrix..
I'd give bonus points to anyone who links a system like the one described above to a real time set-up like the Redwood, CA police department is using to remotely monitor for gunshots in high crime areas.
I'm sitting here in front of a Powerbook G3/400, while my B&W G3 500 (upgraded from 300 for $30 after I sold the g3/300 on eBay) serves files to a cluster of linux boxes via NFS from MOSX.. I haven't used a floppy disk for anything other than maintaining a few garbage Gateway and Dell machines for the last 4 years..
Your BIOS comment shows your ignorance. Macs, like Sun boxes I believe, use openFirmware rather than BIOS, and upgrading the OF is typically trivial (patches are typically shipped as small executables, run the executable, reboot the machine and you're done).
Here's a neat trick you can ask a Mac user to show you some time.. Launch the energy saver control panel under OS 8+, set the start up and shutdown/sleep schedule. Close the control panel. The machine will alter a few settings in OF. If you open the system disk control panel and click on the MOSX drive, before shutting down the machine. The OF will still watch the clock and fire up selected OS, even if you've told it to launch MOSX rather than OS 8+.. I've never seen a PC start-up and shutdown on its own, sure they can reboot, but I'm talking about effectively hitting the power button.
The dimples on golf balls act to trip the boundary layer from laminar to turbulent. This transition pushes the point of boundary layer separation to the trailing side of the ball, which reduces the pressure drag on the ball. Note: the transition from laminar to turbulent flow is probably the result of the dimples exciting instabilities in the BL
Now, as for flow control techniques for drag reduction and separation control, this is currently the most active area of fluid dynamics research. I just returned from the AIAA meeting in Denver and participated in a poster session where Boeing/Pratt & Whitney were showing off their C-17 project. Using pulsed jets of air to mix out the jet shear layer more rapidly. United Technologies Research Center had a poster, as well as a nice, talk discussing dynamic flow separation control on helicopter rotor blades. A group from UCDavis was showing off some MEMS MicroFlaps that they are investigating as potential replacments for the large overweight and extremely complex high lift devices found on most large aircraft. Then there was a group at Notre Dame, investigating Phased Plasma actuators (think surface mounted glow plugs) as a means of controlling high speed flows.
The passive techniques used in golf balls is also a large area of interest. I have spent a while talking to some folks from Princeton who've been making measurments for Callaway, and attempting to improve the flight characteristic of their balls. Someone mentioned vortex generators, and feel compelled to mention that NASA Langley, as well as a number of universities, has been playing with MicroVGs for quite a while now. There is also a group of folks using dynamic VGs and fluidic VGs (typically referred to as Synthetic Jets) in the research community.
The biggest problems with the application of flow control techniques to practical problems are size, weight, power requirements, and robustness. I could probably reduce the drag on my Honda appreciably within a couple weeks, using some of the stuff I play with in my lab. BUT the overall fuel efficiency may not make improve noticably due to the power requirements of active controll and passive techniques are typically tuned to a specific set of flow conditions. Then there's the car wash issue...