Abstract: An optical beam delivery device includes: a first length of fiber having a first refractive index profile (RIP) to enable modification of one or more beam characteristics of an optical beam having a first beam shape; an a second length of fiber having at least one beam-shaping confinement region and situated to receive the optical beam from the first length of fiber, wherein the at least one beam shape-modifying confinement region has a quadrilateral cross-section.

Abstract: A method of casting a low alloy steel using a mold is disclosed. The method includes receiving the mold having a foam pattern disposed within a sand casing. The received foam pattern is coated with a permeable refractory coating and is disposed between compacted sand and the sand casing. The method further includes pouring a molten metal comprising a low alloy steel having a carbon content in a range from about 0.1 to about 0.4 percent into the mold so as to vaporize the foam pattern and remove gasification products through the permeable refractory coating, to form a low alloy steel casting. Further, the method includes removing the low alloy steel casting from the mold.

Abstract: A method of materials processing using an optical beam includes: launching the optical beam into a first length of fiber having a first refractive-index profile (RIP); coupling the optical beam from the first length of fiber into a second length of fiber having a second RIP; modifying one or more beam characteristics of the optical beam in the first length of fiber, in the second length of fiber, or in the first and second lengths of fiber; and/or generating an output beam, having the modified one or more beam characteristics of the optical beam, from the second length of fiber. The first RIP can be the same as or differ from the second RIP. The modifying of the one or more beam characteristics can include changing the one or more beam characteristics from a first state to a second state. The first state can differ from the second state.

Abstract: Systems and methods for modifying an optical beam and adjusting one or more beam characteristics of an optical beam are provided. The system may include a first length of fiber operably coupled with an optical beam source and configured to receive an optical beam therefrom. The system may also include a perturbation device operably coupled with the first length of fiber and configured to modify the optical beam traversing therethrough, and a second length of fiber operably coupled with the first length of fiber and configured to receive the modified optical beam therefrom. The system may further include a beam shaping assembly configured to receive the modified optical beam from the second length of fiber, adjust one or more beam characteristics of the modified optical beam, and direct the adjusted optical beam to a downstream process.

Abstract: An optical beam delivery system, includes: an optical beam source; a fiber assembly situated to receive and modify one or more beam characteristics of an optical beam; and a nonlinear frequency-conversion stage in optical communication with the fiber assembly and situated to receive and frequency-convert an optical beam from a first wavelength to one or more second wavelengths. The fiber assembly includes: a first length of fiber comprising a first RIP formed to enable modification of the one or more beam characteristics of the optical beam by a perturbation device, and a second length of fiber having a second RIP coupled to the first length of fiber, the second RIP formed to confine at least a portion of modified beam characteristics of the optical beam within one or more confinement regions. The first RIP and the second RIP are different.

Abstract: A method for forming an article includes: forming a melt pool; exposing the melt pool to an optical beam having at least one beam characteristic; forming a keyhole cavity in the melt pool, the keyhole cavity having at least one keyhole cavity property; and modifying the at least one beam characteristic in response to a change in the keyhole cavity property.

Abstract: A method of processing by controlling one or more beam characteristics of an optical beam may include: launching the optical beam into a first length of fiber having a first refractive-index profile (RIP); coupling the optical beam from the first length of fiber into a second length of fiber having a second RIP and one or more confinement regions; modifying the one or more beam characteristics of the optical beam in the first length of fiber, in the second length of fiber, or in the first and second lengths of fiber; confining the modified one or more beam characteristics of the optical beam within the one or more confinement regions of the second length of fiber; and/or generating an output beam, having the modified one or more beam characteristics of the optical beam, from the second length of fiber. The first RIP may differ from the second RIP.

Abstract: A method for forming an article includes providing a material having a first material property; forming a melt pool by exposing the material to an optical beam having at least one beam characteristic, wherein the melt pool has at least one melt pool property determinative of a second material property of the material; and modifying the at least one beam characteristic in response to a change in the melt pool property.

Abstract: A method of making a porous three-dimensional object.

Abstract: A ductile iron composition including, by weight: about 3.1% to about 3.6% C; about 3.5% to about 4.0% Si; about 0.035% to about 0.050% Mg; about 0.001% to about 0.004% Ce; up to about 0.005% Sb; about 0.008% to about 0.016% S; up to about 0.04% P; up to about 0.3% Mn; and balance iron and incidental impurities; The ductile iron composition includes a ratio of Sb/Ce greater than or equal to about 1.25, has a ferritic microstructure and graphite nodules, and greater than about 65% of the graphite nodules having a highly spherical geometry. A method and apparatus for forming a ductile iron composition are also disclosed.

Abstract: Refractory slurry for use in coating a foam cluster to provide a foam pattern for lost foam casting is provided. The slurry includes a catalyst capable of catalyzing reactions for vaporizing the foam cluster. A foam pattern with a refractory coating including the catalyst and processes for preparing the foam pattern and using the foam pattern are also provided.

Abstract: A method of casting a low alloy steel using a mold is disclosed. The method includes receiving the mold having a foam pattern disposed within a sand casing. The received foam pattern is coated with a permeable refractory coating and is disposed between compacted sand and the sand casing. The method further includes pouring a molten metal comprising a low alloy steel having a carbon content in a range from about 0.1 to about 0.4 percent into the mold so as to vaporize the foam pattern and remove gasification products through the permeable refractory coating, to form a low alloy steel casting. Further, the method includes removing the low alloy steel casting from the mold.

Abstract: Various turbine component preforms are disclosed having near-net shape features. In one embodiment, a turbine casing preform is disclosed. The turbine casing preform includes an as-cast body comprising a partially cylindrical wall section of a turbine casing, the wall section having an inner surface and an outer surface. The turbine casing preform also includes a circumferentially-extending vane slot formed in the wall section on the inner surface. In another embodiment, a turbine nozzle diaphragm preform is disclosed. The turbine nozzle diaphragm preform includes an as-cast body comprising a partially-cylindrical wall section of a turbine nozzle diaphragm having an inner surface and an outer surface. The turbine nozzle diaphragm preform also includes an as-cast, circumferentially-extending seal member projecting from one of the outer surface or inner surface.

Abstract: Refractory slurry for use in coating a foam cluster to provide a foam pattern for lost foam casting is provided. The slurry includes a catalyst capable of catalyzing reactions for vaporizing the foam cluster. A foam pattern with a refractory coating including the catalyst and processes for preparing the foam pattern and using the foam pattern are also provided.

Abstract: Various turbine component preforms are disclosed having near-net shape features. In one embodiment, a turbine casing preform is disclosed. The turbine casing preform includes an as-cast body comprising a partially cylindrical wall section of a turbine casing, the wall section having an inner surface and an outer surface. The turbine casing preform also includes a circumferentially-extending vane slot formed in the wall section on the inner surface. In another embodiment, a turbine nozzle diaphragm preform is disclosed. The turbine nozzle diaphragm preform includes an as-cast body comprising a partially-cylindrical wall section of a turbine nozzle diaphragm having an inner surface and an outer surface. The turbine nozzle diaphragm preform also includes an as-cast, circumferentially-extending seal member projecting from one of the outer surface or inner surface.

Abstract: A shaped antenna element that radically reduces the physical size needed for resonance without the use of lossy loading elements, while at the same time allowing direct connection to a coaxial feeder. The element is composed of at least two sub-elements in close proximity to each other, coupled electrically to each other such that the radiation resistance of the composite element is increased substantially. The composite element can be used either as an antenna or part of an antenna that consists of multiple such elements in order to provide increased directivity.

Abstract: A shaped antenna element that radically reduces the physical size needed for resonance without the use of lossy loading elements, while at the same time allowing direct connection to a coaxial feeder. The element is composed of at least two sub-elements in close proximity to each other, coupled electrically to each other such that the radiation resistance of the composite element is increased substantially. The composite element can be used either as an antenna that consists of multiple such elements in order to provide increased directivity.

Abstract: In a nuclear-reactor power-generating installation having a main and an auxiliary steam-generating boiler, both arranged to receive heat from the reactor core (for example by circulation of reactor coolant gas), and having a turbogenerator which includes a multistage steam turbine through whose stages the steam from the main boiler passes in sequence, there being a steam reheater unit connected between two of the stages to provide reheating of the steam from the main boiler, the invention provides that the auxiliary boiler is connected to supply to the reheater unit steam which reheats the said steam from the main boiler.

Abstract: In a nuclear reactor installation comprising a fluid-cooled nuclear heat source within a primary pressure vessel, the latter is enclosed within a secondary containment means which comprises a lower wall portion surrounding the primary pressure vessel, an annular portion extending out from the lower wall portion, and an upper portion integral with the annular portion and extending over it and over the primary pressure vessel and housing handling means for lifting fuel and other reactor components through normally sealed vertical penetrations in the roof of the primary pressure vessel (giving access to the reactor core) and in the said annular portion (giving access to new and spent fuel stores and other auxiliary facilities disposed outside the secondary containment and wholly or partly below the said annular portion).

Abstract: A gas-cooled nuclear reactor has a main circulatory system for the gaseous coolant incorporating one or more main energy converting units, such as gas turbines, and an auxiliary circulatory system for the gaseous coolant incorporating at least one steam generating boiler arranged to be heated by the coolant after its passage through the reactor core to provide steam for driving an auxiliary steam turbine, such an arrangement providing a simplified start-up procedure also providing emergency duties associated with long term heat removal on reactor shut down.