摘要:
A system supporting the formation and propagation of tunable highly nonlinear pulses using granular chains composed of non-spherical granular systems. Such a system may be used to support the creation of tunable acoustic band gaps in granular crystals formed of particles with different geometries (spherical or not) in which the tunability is achieved by varying the static precompression, type of excitation and/or pulse amplitude in the system.
摘要:
A tunable frequency acoustic rectifier that is a granular crystal composed of a statically compressed one-dimensional array of particles in contact, containing a light mass defect near a boundary. The tunable frequency acoustic rectifier is nonlinear and contains tunable pass and stop bands in their dispersion relation. Vibrations at selected frequencies applied to the granular crystal from the side near the defect will cause the system to bifurcate at a critical input amplitude and subsequently jump to quasiperiodic and chaotic states with broadband frequency content. Some of this frequency content lies within the pass bands and will propagate through the crystal. Vibrations at the same frequencies applied to the other side of the granular crystal will not bifurcate, and little energy is transmitted.
摘要:
Syntheses of carbon nanotubes (CNT) are disclosed. The syntheses can take place on a thermally oxidized silicon surface placed inside a furnace prior to a reaction. The setup can have many variables that could affect the resulting CNT arrays, including flow rate and composition of carrier gas, flow rate and composition of precursor solution, and temperature. By varying such variables the density of the resulting CNT arrays can be controlled.
摘要:
A method and system supporting the formation and propagation of tunable highly nonlinear pulses using granular chains composed of non-spherical granular systems. Such a method and system may be used to support the creation of tunable acoustic band gaps in granular crystals formed of particles with different geometries (spherical or not) in which the tunability is achieved by varying the static precompression, type of excitation and/or pulse amplitude in the system.
摘要:
A method and system for creating highly nonlinear solitary waves for use in performing nondestructive evaluation of structures and materials. The method and system use an apparatus having a spring loaded adjustable striker, a chain of granular particles, and a reloading device that allows for repeated activation of the adjustable striker.
摘要:
A method and apparatus for nondestructive evaluation (NDE) of structures and materials using a highly nonlinear medium for the generation and detection of one or multiple highly nonlinear pulses (or highly nonlinear waves) impinging on a material or structure. The apparatus includes pulse exciters that induce the propagation of highly nonlinear, weakly nonlinear or linear stress waves in the material, system, or structure to be inspected and/or detectors for the observation and the detection of the output waves from the material/structure being tested. The NDE method includes the use of the tunable highly nonlinear apparatus as impulse exciter alone, or in combination with an accelerometer or a nonlinear sensor to detect the outgoing pulse.
摘要:
Systems and methods for creating sound bullets are described. Such sound bullets are created by controlling and/or redirecting highly nonlinear acoustic waves or pulses propagating through an array of actuators. The controlling and/or redirecting of the acoustic waves or pulses is achieved though methods such as applying pre-compressive forces to the array of actuators or by selection of size, shape and/or material of the actuators.
摘要:
A method and apparatus for nondestructive evaluation (NDE) of structures and materials using a highly nonlinear medium for the generation and detection of one or multiple highly nonlinear pulses (or highly nonlinear waves) impinging on a material or structure. The apparatus includes pulse exciters that induce the propagation of highly nonlinear, weakly nonlinear or linear stress waves in the material, system, or structure to be inspected and/or detectors for the observation and the detection of the output waves from the material/structure being tested. The NDE method includes the use of the tunable highly nonlinear apparatus as impulse exciter alone, or in combination with an accelerometer or a nonlinear sensor to detect the outgoing pulse.
摘要:
A method and system for creating highly nonlinear solitary waves for use in performing nondestructive evaluation of structures and materials. The method and system use an apparatus having a spring loaded adjustable striker, a chain of granular particles, and a reloading device that allows for repeated activation of the adjustable striker.
摘要:
Systems and methods for creating sound bullets are described. Such sound bullets are created by controlling and/or redirecting highly nonlinear acoustic waves or pulses propagating through an array of actuators. The controlling and/or redirecting of the acoustic waves or pulses is achieved though methods such as applying pre-compressive forces to the array of actuators or by selection of size, shape and/or material of the actuators.