The reason the idea of a "tsunami bomb" was considered was basically because little was known about tsunamis in the 1940s. Tsunamis are generated by a vertical disturbance of the water column, with the chief perpetrators being undersea earthquakes (that cause vertical shifts in the sea floor), volcano eruptions and the recently popularized meteorite impact scenario.
It would be extremely difficult to target such a thing since they are basically created by the equivalent of impulse or point sources and propagate in a circle around the point of origin. Those who think that shape charges could be used to target tsunamis should sit in a bathtub and attempt to target a surface gravity wave by poking their finger or dropping their rubber ducky in the water. You can push a whole lot of water in one direction, but that would be an advective process that would propagate not nearly as far as a wave.
The damage done by tsunamis is due to their kinetic energy being transformed into potential energy when they near land. After generation, they travel at tremendous speeds through the ocean. The speed of propagation is basically SQRT(G*H) where G is the gravitational constant and H the depth of the water, i.e. hundreds of miles an hour in the deep ocean. Their surface signature, on the other hand, is lost in the noise of the other waves on the ocean surface.
When they near land and the seafloor shallows, the hundreds of miles an hour worth of kinetic energy is transformed into a huge wall of water that, while moving much more slowly than before, still packs a hell of a wallop. Another key factor is the general variation of the seafloor topography as it shallows. Refraction and reflection processes can focus energy such that what would be a 5-10 foot wave on a flatly sloping beach could be several times higher. This is basically the same process that makes some beaches much better for surfing since the offshore topography focuses the wave energy.
You could probably use an explosion to effectively generate a tsunami if the situation were just right, i.e. you have a seafloor configuration near your target favorable for refraction processes significantly increasing the size of your generated wave. Otherwise it would take one hell of a huge explosion to impart the same sort of energy you get from a massive seafloor shift or a large bolide impact, and that could end up doing as much damage to you as to your target.
As to the suggestion that additional waves can be generated to cancel out a tsunami, ponder (for just a second, Pinky) how you can cancel out a tsunami that has reached the shore and become a huge wall of water. At that point it's no longer a wave since nonlinear processes have turned turned the tsunami into an advective process. And if you attempt to cancel it out while its still a wave in the deep sea the counter-wave and the original will certainly sum to zero at some point, and then continue on in opposite directions to wreak havoc.
I'd recommend checking out the University of Washington's Tsunami site for further theoretical and historical information. On a side note, many of the foundations of modern oceanography were laid by the research performed by Walter Munk and others during WWII. Most of the work involved wave forecasting such that the wave environment during certain invasions could be predicted sufficiently accurately to avoid overly large surf conditions.
There is indeed a version of grep for XML-based records. It's called sgrep (structured grep) and "is a tool for searching and indexing text, SGML, XML and HTML files and filtering text streams using structural criteria." It is based on the concept of regions, i.e. nonempty text substrings that are typically occurrences of constant stsrings, SGML tags, or meaningful text elements recognizable via delimiting strings or the built-in SGML, XML and SGML parser.
The LinuXML Project is "devoted to changing the UNIX de facto standard for inter-process communication (IPC) and storage from line-based ASCII records to XML."
Slashdot Mirror
It would be extremely difficult to target such a thing since they are basically created by the equivalent of impulse or point sources and propagate in a circle around the point of origin. Those who think that shape charges could be used to target tsunamis should sit in a bathtub and attempt to target a surface gravity wave by poking their finger or dropping their rubber ducky in the water. You can push a whole lot of water in one direction, but that would be an advective process that would propagate not nearly as far as a wave.
The damage done by tsunamis is due to their kinetic energy being transformed into potential energy when they near land. After generation, they travel at tremendous speeds through the ocean. The speed of propagation is basically SQRT(G*H) where G is the gravitational constant and H the depth of the water, i.e. hundreds of miles an hour in the deep ocean. Their surface signature, on the other hand, is lost in the noise of the other waves on the ocean surface.
When they near land and the seafloor shallows, the hundreds of miles an hour worth of kinetic energy is transformed into a huge wall of water that, while moving much more slowly than before, still packs a hell of a wallop. Another key factor is the general variation of the seafloor topography as it shallows. Refraction and reflection processes can focus energy such that what would be a 5-10 foot wave on a flatly sloping beach could be several times higher. This is basically the same process that makes some beaches much better for surfing since the offshore topography focuses the wave energy.
You could probably use an explosion to effectively generate a tsunami if the situation were just right, i.e. you have a seafloor configuration near your target favorable for refraction processes significantly increasing the size of your generated wave. Otherwise it would take one hell of a huge explosion to impart the same sort of energy you get from a massive seafloor shift or a large bolide impact, and that could end up doing as much damage to you as to your target.
As to the suggestion that additional waves can be generated to cancel out a tsunami, ponder (for just a second, Pinky) how you can cancel out a tsunami that has reached the shore and become a huge wall of water. At that point it's no longer a wave since nonlinear processes have turned turned the tsunami into an advective process. And if you attempt to cancel it out while its still a wave in the deep sea the counter-wave and the original will certainly sum to zero at some point, and then continue on in opposite directions to wreak havoc.
I'd recommend checking out the University of Washington's Tsunami site for further theoretical and historical information. On a side note, many of the foundations of modern oceanography were laid by the research performed by Walter Munk and others during WWII. Most of the work involved wave forecasting such that the wave environment during certain invasions could be predicted sufficiently accurately to avoid overly large surf conditions.
There is indeed a version of grep for XML-based records. It's called sgrep (structured grep) and "is a tool for searching and indexing text, SGML, XML and HTML files and filtering text streams using structural criteria." It is based on the concept of regions, i.e. nonempty text substrings that are typically occurrences of constant stsrings, SGML tags, or meaningful text elements recognizable via delimiting strings or the built-in SGML, XML and SGML parser.
The LinuXML Project is "devoted to changing the UNIX de facto standard for inter-process communication (IPC) and storage from line-based ASCII records to XML."