摘要:
A shock wave barrier comprises a periodic structure having the proper symmetry and local contrast modulation of the acoustic index to divert an incident shock wave by using constructive/destructive interference phenomena that produce a “band gap” in the transmission spectrum of the periodic structure. In general, shock wave energy within the band gap is reflected from the structure. Defect cavities may be formed in the periodic structure to create transmission resonances or “windows” in the band gap. A portion of the incident energy passes through the window and is concentrated in the defect cavities where it is dissipated by other means. The band gap can be quite wide, at least 50% of the center wavelength, and thus can provide an effective barrier from a wide variety of threats with varying blast pressure and range. The structure may be periodic in two or three dimensions providing a band gap barrier in two or three dimensions, respectively.
摘要:
An acoustic crystal explosive, which gains its properties from both its periodic structure and its composition, may be configured to suppress or enhance the sensitivity of detonation of the explosive in response to an acoustic wave. An explosive material and a medium (explosive or inactive) are arranged in a periodic array that provides local contrast modulation of the acoustic index to define a band gap in the acoustic transmission spectrum of the explosive materials. At least one defect cavity in the periodic array creates a resonance in the band gap. The defect cavity concentrates energy from an incident acoustic (shock) wave to detonate the explosive. Multiple defect cavities may be configured to provide a desired shaped charge or volumetric detonations. Means may be provided to reprogram the defect cavity(ies) to reconfigure the explosive.
摘要:
A shock wave barrier comprises a periodic structure having the proper symmetry and local contrast modulation of the acoustic index to divert an incident shock wave by using constructive/destructive interference phenomena that produce a “band gap” in the transmission spectrum of the periodic structure. In general, shock wave energy within the band gap is reflected from the structure. Defect cavities may be formed in the periodic structure to create transmission resonances or “windows” in the band gap. A portion of the incident energy passes through the window and is concentrated in the defect cavities where it is dissipated by other means. The band gap can be quite wide, at least 50% of the center wavelength, and thus can provide an effective barrier from a wide variety of threats with varying blast pressure and range. The structure may be periodic in two or three dimensions providing a band gap barrier in two or three dimensions, respectively.
摘要:
An acoustic crystal explosive, which gains its properties from both its periodic structure and its composition, may be configured to suppress or enhance the sensitivity of detonation of the explosive in response to an acoustic wave. An explosive material and a medium (explosive or inactive) are arranged in a periodic array that provides local contrast modulation of the acoustic index to define a band gap in the acoustic transmission spectrum of the explosive materials. At least one defect cavity in the periodic array creates a resonance in the band gap. The defect cavity concentrates energy from an incident acoustic (shock) wave to detonate the explosive. Multiple defect cavities may be configured to provide a desired shaped charge or volumetric detonations. Means may be provided to reprogram the defect cavity(ies) to reconfigure the explosive.
摘要:
An apparatus for displaying a scene with light in a range of infrared wavelengths, includes: an array of elements configured to emit light in a range of infrared wavelengths, each element having one or more nanotubes; a stimulator configured to apply a stimulus to each element in the array in order for each element to emit light in the range of infrared wavelengths; and a processor configured to send a signal to the stimulator in order to apply the stimulus to one or more selected elements in the array to display the scene.
摘要:
Isotopically-enriched graphene and isotope junctions are epitaxially grown on a catalyst substrate using a focused carbon ion beam technique. The focused carbon ion beam is filtered to pass substantially a single ion species including a single desired carbon isotope. The ion beam and filtering together provide a means to selectively isotopically-enrich the epitaxially-grown graphene from given carbon precursor and to selectively deposit graphene enriched with different carbon isotopes in different regions.
摘要:
An apparatus for displaying a scene with light in a range of infrared wavelengths, includes: an array of elements configured to emit light in a range of infrared wavelengths, each element having one or more nanotubes; a stimulator configured to apply a stimulus to each element in the array in order for each element to emit light in the range of infrared wavelengths; and a processor configured to send a signal to the stimulator in order to apply the stimulus to one or more selected elements in the array to display the scene.
摘要:
In an embodiment of methods and systems for optical focusing For laser guided seekers using negative index metamaterial, the methods and systems comprise a light focusing system comprising: a lens comprising a negative index metamaterial to focus at least one selected wavelength while defocusing other wavelengths, and a sensor upon which the lens focuses the selected wavelength.
摘要:
Stone Wales defect pairs in a carbon nanostructure are used to store energy. Energy is released by a chain reaction of phonons disrupting the defect pairs to generate more phonons until the lattice returns to its original hexagonal form and the energy is released in the form of lattice vibrations. Devices may be configured as a battery to release electrical energy in a controlled manner or as an explosive to release energy in an uncontrolled manner.
摘要:
Methods and systems for extracting energy from a heat source using photonic crystals with defect cavities generally comprise a photonic crystal, a cavity, and a converter. The photonic crystal is responsive to a heat source and generates an electromagnetic beam in response to incidence with the heat source. The photonic crystal exhibits a band gap such that wavelengths within the band gap are substantially confined within the photonic crystal. The cavity is substantially within the crystal and is responsive to the electromagnetic beam such that the cavity transmits the electromagnetic beam to a specified location. The converter is substantially collocated with the specified location and extracts energy in response to incidence with the electromagnetic beam.