Abstract: A helmet configured to protect a human head against mild traumatic brain injury upon impact includes an outer shell and a liner consisting of pairs of fluid fillable flexible fluid chambers fluidly connected to each other by fluid connections between each of the pairs of fluid fillable flexible fluid chambers being spaced on opposite sides of the helmet and configured to fill a space between the head and the outer shell when the helmet is positioned on the head. Impact resistant flexible pads are also inside the liner and are spaced around an inner circumference of the outer shell adjacent to each of the fluid fillable flexible fluid chambers. A flexible inner shell inside the liner is configured to fit closely on the head.

Abstract: A rigid structure propellant management device (PMD) liquid storage tank includes an outer shell and internal structures inside the outer shell that include a plurality of vertical columns each made up of a stack of individual storage cells. Each of the storage cells has solid vertical sidewalls and top and bottom capillary windows that allow vertical liquid transfer between adjacent cells in a vertical column. The top and bottom capillary windows in each of the storage cells have permeabilities that result in a selected direction of liquid flow in each column. A piping and valve system may be connected to the top capillary window of a top storage cell and to the bottom capillary window of a bottom storage cell of each vertical column, configured to allow controlled liquid transfer between adjacent vertical columns so that locations of empty cells in the tank as liquid is drawn from the tank achieves a selected column by column drainage sequence and controls a center of mass of the tank.

Abstract: A metallic positive expulsion fuel tank with stress free weld seams may include a first hemispherical shell with a first edge; and a hemispherical rolling metal diaphragm with a first edge attached to the first hemispherical shell along matching first edges. A second hemispherical shell with a first edge may be attached to the first edge of the first hemispherical shell by a first weld seam thereby forming two interior chambers separated by the hemispherical rolling metal diaphragm. A pressurized gas inlet may be attached to the first hemispherical dome; and a fuel outlet fixture may be attached to the second hemispherical dome. The first weld seam may have been stress relieved by a localized post-weld heat treatment confined to an immediate vicinity of the first weld seam.

Abstract: A thin wall spinformed metallic tank shell includes a first region with a first thickness and at least one second region with a second thickness greater than the first thickness including structural features formed by an additive manufacturing process, where the features are added outside and inside of the metallic tank shell and can include: polar bosses added to one or both external polar regions of a spherical section of the tank; mounting tabs on a circumferential skirt of the tank; mounting rings containing threaded holes attached to the interior or exterior surface of the tank; mounting trunnions attached to the external surface of the tank; propellant management devices attached to the interior surface of the tank; structural reinforcement vanes and ribs attached to the inside surface of the tank; and brackets and/or shelves attached to the inside surface of the tank.

Abstract: A metallic positive expulsion fuel tank with stress free weld seams may include a first hemispherical shell with a first edge; a pressurized gas inlet attached to the first hemispherical shell; and a metallic cylinder with first and second edges attached to the first hemispherical shell along matching first edges by a first weld seam. The tank may also include a second hemispherical shell with a first edge attached to a fuel outlet fixture. An elastomeric diaphragm may be attached to the fuel outlet fixture on the second hemispherical shell. The second hemispherical shell may be attached to the second edge of the metallic cylinder along matching edges by a second weld seam thereby forming a positive expulsion fuel tank with two interior chambers separated by the elastomeric diaphragm. The first and second weld seams may be subjected to a localized post-weld stress relief heat treatment in which heating of the tank is confined to a distance of 2 inches (5.

Abstract: A rigid structure propellant management device (PMD) liquid storage tank includes an outer shell and internal structures inside the outer shell that include a plurality of vertical columns each made up of a stack of individual storage cells. Each of the storage cells has solid vertical sidewalls and top and bottom capillary windows that allow vertical liquid transfer between adjacent cells in a vertical column. The top and bottom capillary windows in each of the storage cells have permeabilities that result in a selected direction of liquid flow in each column. A piping and valve system may be connected to the top capillary window of a top storage cell and to the bottom capillary window of a bottom storage cell of each vertical column, configured to allow controlled liquid transfer between adjacent vertical columns so that locations of empty cells in the tank as liquid is drawn from the tank achieves a selected column by column drainage sequence and controls a center of mass of the tank.

Abstract: A method of forming a thick wall section on a specific region of a thin wall spinformed metallic tank shell includes forming a thin wall metallic tank shell blank by spinforming a metal sheet over a mandrel and removing the tank shell blank from the mandrel. The method further includes mounting the blank in an additive manufacturing system and adding metallic structural features to the tank shell according to a 3D model stored in memory in the additive manufacturing system.

Abstract: A method of performing a localized post weld heat treatment on a weld seam in a thin wall metallic body may include attaching thermocouples to the outside surface of the weld seam and covering the weld seam with a thermal insulating blanket. Cooling bands are attached to the outside of the body on both sides of the weld seam. An inert atmosphere enclosure with inlet and exhaust ports is fitted over the weld seam, thermal insulating blanket, and cooling bands. A power supply and control system for an induction coil or coils situated in close proximity to the weld seam are actuated and the weld seam is subjected to a heat treatment without thermally affecting regions of the metallic body adjacent to the weld seam and external to the cooling bands.

Abstract: A helmet configured to protect a human head against mild traumatic brain injury upon impact includes an outer shell and a liner consisting of fluid fillable flexible fluid chambers fluidly connected to each other by fluid connections. The fluid chambers being spaced around the circumference of the helmet and configured to fill a space between the head and the outer shell when the helmet is positioned on the head. Impact resistant flexible pads are also in the liner and are spaced around an inner circumference of the outer shell adjacent to each of the fluid fillable flexible fluid chambers. A flexible inner shell inside the liner is configured to fit closely on the head. The flexible fluid chambers are configured to compress in response to impacting of the helmet on an impact side and to force liquids through the fluid connections to inflate other fluid chambers inside the helmet thereby cushioning the head against a rebound impact on the inside of the helmet.

Abstract: A helmet configured to protect a human head against mild traumatic brain injury upon impact includes an outer shell and a liner consisting of pairs of fluid fillable flexible fluid chambers fluidly connected to each other by fluid connections between each of the pairs of fluid fillable flexible fluid chambers being spaced on opposite sides of the helmet and configured to fill a space between the head and the outer shell when the helmet is positioned on the head. Impact resistant flexible pads are also inside the liner and are spaced around an inner circumference of the outer shell adjacent to each of the fluid fillable flexible fluid chambers. A flexible inner shell inside the liner is configured to fit closely on the head.

Abstract: A metallic positive expulsion fuel tank with stress free weld seams may include a first hemispherical shell with a first edge; a pressurized gas inlet attached to the first hemispherical shell; and a metallic cylinder with first and second edges attached to the first hemispherical shell along matching first edges by a first weld seam. The tank may also include a second hemispherical shell with a first edge attached to a fuel outlet fixture. An elastomeric diaphragm may be attached to the fuel outlet fixture on the second hemispherical shell. The second hemispherical shell may be attached to the second edge of the metallic cylinder along matching edges by a second weld seam thereby forming a positive expulsion fuel tank with two interior chambers separated by the elastomeric diaphragm. The first and second weld seams may be subjected to a localized post-weld stress relief heat treatment in which heating of the tank is confined to a distance of 2 inches (5.

Abstract: A method of forming a thick wall section on a specific region of a thin wall spinformed metallic tank shell includes forming a thin wall metallic tank shell blank by spinforming a metal sheet over a mandrel and removing the tank shell blank from the mandrel. The method further includes mounting the blank in an additive manufacturing system and adding metallic structural features to the tank shell according to a 3D model stored in memory in the additive manufacturing system.

Abstract: A metallic positive expulsion fuel tank with stress free weld seams may include a first hemispherical shell with a first edge; and a hemispherical rolling metal diaphragm with a first edge attached to the first hemispherical shell along matching first edges. A second hemispherical shell with a first edge may be attached to the first edge of the first hemispherical shell by a first weld seam thereby forming two interior chambers separated by the hemispherical rolling metal diaphragm. A pressurized gas inlet may be attached to the first hemispherical dome; and a fuel outlet fixture may be attached to the second hemispherical dome. The first weld seam may have been stress relieved by a localized post-weld heat treatment confined to an immediate vicinity of the first weld seam.

Abstract: A method of performing a localized post weld heat treatment on a weld seam in a thin wall metallic body may include attaching thermocouples to the outside surface of the weld seam and covering the weld seam with a thermal insulating blanket. Cooling bands are attached to the outside of the body on both sides of the weld seam. An inert atmosphere enclosure with inlet and exhaust ports is fitted over the weld seam, thermal insulating blanket, and cooling bands. A power supply and control system for an induction coil or coils situated in close proximity to the weld seam are actuated and the weld seam is subjected to a heat treatment without thermally affecting regions of the metallic body adjacent to the weld seam and external to the cooling bands.

Abstract: A demisable fuel supply system for a satellite includes a pressurized aluminum alloy tank with an aluminum alloy propellant management device therein. The propellant management device (PMD) can have any capillary action surface tension fluid transport features known in the art. Selected inner surfaces of the tank and the PMD are covered with a plasma powder sprayed titanium based coating to guarantee propellant wettability and corrosion resistance of the fuel supply system.

Abstract: A demisable fuel supply system for a satellite includes a pressurized aluminum alloy tank with an aluminum alloy propellant management device therein. The propellant management device (PMD) can have any capillary action surface tension fluid transport features known in the art. Selected inner surfaces of the tank and the PMD are covered with a titanium based coating to guarantee propellant wettability and corrosion resistance of the fuel supply system.

Abstract: A demisable fuel supply system for a satellite includes a pressurized aluminum alloy tank with an aluminum alloy propellant management device therein. The propellant management device (PMD) can have any capillary action surface tension fluid transport features known in the art. Selected inner surfaces of the tank and the PMD are covered with a titanium based coating to guarantee propellant wettability and corrosion resistance of the fuel supply system.

Abstract: A demisable fuel supply system for a satellite includes a pressurized aluminum alloy tank with an aluminum alloy propellant management device therein. The propellant management device (PMD) can have any capillary action surface tension fluid transport features known in the art. Selected inner surfaces of the tank and the PMD are covered with a plasma powder sprayed titanium based coating to guarantee propellant wettability and corrosion resistance of the fuel supply system.

Abstract: Disclosed is a variable polarity power supply for arc welding that quickly switches between polarities in order to more easily re-establish the arc. The variable polarity power supply includes a current-limited boost circuit for providing increased open circuit voltage to re-establish the arc, while limiting the re-establishment current. The variable polarity power supply is particularly suitable for computer-controlled welding applications because it periodically restarts the arc in either direction without using high frequency radiation, and provides quick switching times along with a low reverse current to reduce the heat in the torch, thereby increasing the longevity of the torch.