Abstract: A technique for protecting a structure from an impact with ice involves providing a horizontal spall initiator extending from the wall a distance of 1 to 10 cm, the horizontal spall initiator being resilient to the ice impact, and formed by blade segments having a blade width less than ½ a thickness of an expected hard zone of the ice; and situating the horizontal spell initiator at an elevation of the expected hard zone. Situating the horizontal spall initiator at an elevation of the hard zone may involve providing an elevation control mechanism (e.g. buoyancy, mechanical, or hydrodynamic), or may involve a panel with a plurality of horizontal spell initiators at respective elevations. The horizontal spell initiator may be driven.

Abstract: A technique for protecting a structure from an impact with ice involves providing a horizontal spall initiator extending from the wall a distance of 1 to 10 cm, the horizontal spall initiator being resilient to the ice impact, and formed by blade segments having a blade width less than ½ a thickness of an expected hard zone of the ice; and situating the horizontal spell initiator at an elevation of the expected hard zone. Situating the horizontal spall initiator at an elevation of the hard zone may involve providing an elevation control mechanism (e.g. buoyancy, mechanical, or hydrodynamic), or may involve a panel with a plurality of horizontal spell initiators at respective elevations. The horizontal spell initiator may be driven.

Abstract: A technique for optical measurement of a thickness of a layer on a surface uses diffuse reflections at opposite boundaries of the layer, operates on transparent, or translucent layers. The thickness is determined by computing a separation between the centers of the two diffuse reflections, and using the index of refraction of the layer, and geometric properties of a beam and detector with respect to the surface. The technique is useful for quantifying thickness of a layer of rime ice, glaze ice, frosted ice, or water, for example.

Abstract: A technique for optical measurement of a thickness of a layer on a surface uses diffuse reflections at opposite boundaries of the layer, operates on transparent, or translucent layers. The thickness is determined by computing a separation between the centers of the two diffuse reflections, and using the index of refraction of the layer, and geometric properties of a beam and detector with respect to the surface. The technique is useful for quantifying thickness of a layer of rime ice, glaze ice, frosted ice, or water, for example.

Abstract: Apparatus for detecting loads applied to a surface, including a platen providing a continuous surface which is stiff relative to the loads being detected, a load receiving sheet extending over the platen surface and having an outer surface exposed to the loads, and, preferably, a layer of deformable material underlying the sheet and which is deformed when loads are applied to the sheet. A separator having regularly spaced apertures or gaps lies between the deformable layer and the platen surface, this being thin enough that loads to be measured applied to the outer surface of the sheet cause parts of the deformable layer to be pushed through the apertures or gaps into contact with the platen surface. The platen is preferably transparent, and a video camera is provided for viewing the platen surface and detecting areas where the deformable layer contacts the platen surface.

Abstract: Apparatus for sensing and/or measuring load distribution applied to a surface, having a platen providing a continuous, stiff, unapertured surface, a flexible load receiving sheet extending over the platen surface, and a layer of deformable material separating and capable of contacting both the platen surface and the load receiving sheet and which is compressed in thickness when loads are applied to the sheet. The deformable layer is provided with regularly spaced voids, for example holes or gaps, such that the deformable material bulges into these voids when compressed across its thickness. Either the platen or the load receiving sheet is transparent, and the deformable layer is viewed through a surface of the transparent member to detect reductions in the areas of the voids caused by loading of the load receiving sheet. The viewing may be done by a video camera.

Abstract: A method and an apparatus are disclosed for remotely determining the thickness of a transparent or semi-transparent suspended sheet or solid or liquid layer, e.g. ice, on a solid surface which is either light-absorbent or highly reflective. The invention proposes directing a coherent beam of light onto a location on the layer such that the beam undergoes partial reflection from the top of the layer and partial reflection from the bottom of the layer or the underlying surface. Due to the coherency of the beam, two overlapping speckle patterns are produced which give rise to an interference pattern having interference fringes. The pattern can be caused to shift across the field of view and the shift, determined by a number of the passing interference fringes can be interpreted in terms of the thickness of the layer.

Abstract: An apparatus and method are provided for remotely detecting ice on a polarization preserving surface. A target location on the surface is irradiated with two cross-polarized beams of coherent light. A determination is then made as to whether the speckle patterns from each of the two beams interfere with one another. If interference of the speckle patterns from the two beams is detected, ice or some other birefringent material is said to be present on the surface.

Abstract: There is described a method and apparatus for detection and thickness evaluation of a buildup of a solid, e.g. ice, or liquid on a solid surface, such as ice on a body of an aircraft. The apparatus comprises a source of a narrow beam of radiation and a means for remote evaluation of the size of a luminous area created on the solid surface by the beam. The method of the invention involves measuring the size of the luminous area and determining the thickness of any built-up layer, if sufficiently transparent, using a formula which uses the dependency of the size of the luminous are on the thickness of the layer and the refraction index of the medium. Differentiation between ice and a liquid is possible by evaluating regularity of illumination of the luminous area.

Abstract: There is described a method and apparatus for detection and thickness evaluation of a buildup of ice or liquid on a solid surface, especially on a body of an aircraft. The apparatus comprises a source of a narrow beam of radiation and a means for remote evaluation of the size of a luminous area created on the solid surface by the beam. The method of the invention involves measuring the size of the luminous area and determining the thickness of any built-up layer, if sufficiently transparent, using a formula which uses the dependency of the size of the luminous are on the thickness of the layer and the refraction index of the medium. Differentiation between ice and a liquid is possible by evaluating regularity of illumination of the luminous area.