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Shooting darts with a blowgun is an extremely stealthy, and even lethal, hunting technique if the darts are poisoned with plant extracts or animal secretions. In Guyana, Suriname, French Guiana, some isolated areas in South America, and in the Amazon and Orinoco basins, blowgun hunters fill the tips of their darts with curare .
The launch tube was designed to be sealed at both ends, with the rear seal being blown off by the rocket motor and the front by pressurized gas released by the guidance system's gyroscope. In practice, both proved unreliable, but remedial action solved the problems.
Concrete work is efficient and controlled as CCS functions as ready-made forms; CCS with concrete forms a flexible slab that accommodates minor subgrade movement and prevents cracking. In medium and low flow-velocities, CCS with geomembranes and gravel cover can be used to create impermeable channels, thereby eliminating the need for concrete.
The kestrosphendone, or kestros, was a sling-launched dart, invented in 168 BC for the Third Macedonian War, probably similar to hand-thrown darts of the period. Casting one (according to surviving records) requires a specially designed sling with two unequal loops, though it is not clear whether this is a stave-sling or more closely resembles ...
The M829 dart has a ballistic nose and six tail fins made of aluminum. It is carried in the gun tube by a four-piece aluminum sabot, which separates into four "petals" soon after the round leaves the gun tube. [2] The propulsion system uses an obturating case base with a semi-combustible cartridge wall.
The tremie concrete placement method uses a vertical or nearly vertical pipe, through which concrete is placed by gravity feed below water level. [4]The lower end of the pipe is kept immersed in fresh concrete so that concrete rising from the bottom displaces the water above it, thus limiting washing out of the cement content of the fresh concrete at the exposed upper surface.
Shotcrete, gunite (/ ˈ ɡ ʌ n aɪ t /), or sprayed concrete is concrete or mortar conveyed through a hose and pneumatically projected at high velocity onto a surface. This construction technique was invented by Carl Akeley and first used in 1907. [1]: 7 The concrete is typically reinforced by conventional steel rods, steel mesh, or fibers.
By 1963, a new structural system of framed tubes had appeared in skyscraper design and construction. Fazlur Rahman Khan, a structural engineer from Bangladesh (then called East Pakistan) who worked at Skidmore, Owings & Merrill, defined the framed tube structure as "a three dimensional space structure composed of three, four, or possibly more frames, braced frames, or shear walls, joined at or ...