Abstract: A server system that includes a host device initiates an encrypted decision tree model executing on an accelerator coupled with the host device. The encrypted decision tree model encrypted uses an agreed upon encryption schema between the host device and a user device accessing the encrypted decision tree model. The host device receives an input, from the user device, to be evaluated using the encrypted decision tree model. The input is encrypted using the agreed upon encryption schema. The host device using the encrypted decision tree model evaluates the input from the user device without decrypting the input. The accelerator using the encrypted decision tree model generates an encrypted output based on the evaluating. The accelerator device provides the encrypted output to the user device.

Abstract: A method of state permutation logic locking (SPeLL) for sequential circuits. The method includes encrypting original states of a sequential circuit to produce encrypted states, by transitioning an initial order of the original states into a secret permutation of the encrypted states, where the secret permutation is different than the initial order. The method also includes determining a cryptographic key that corresponds to the transition from the initial order of the original states to the secret permutation of the encrypted states, and decrypting the encrypted states, by using the cryptographic key to transition from the secret permutation of the encrypted states back to the initial order of the original states.

Abstract: Improved heat exchangers according to several embodiments are provided. The heat exchangers provide improved heat transfer for air flow in wet and dry operating conditions, while minimizing pressure drop across the heat exchanger in some applications. According to one embodiment, an improved heat exchanger includes a plurality of metal foam fins between adjacent heat exchange conduits, the heat exchange conduits being arranged parallel to each other to define parallel flow paths between an inlet header and an outlet header. The metal foam fins occupy a cross-flow region between adjacent conduits, the fins having a fixed angular orientation or being rotatable in unison to vary the thermal capacitance of the heat exchanger.

Abstract: An improved method and system for treating flue gases from a natural gas furnace are provided. The method and system include an acidic gas trap (AGT) adsorber which enables the continuous adsorption and storage of SOx, NOx redox, and formic acid/CO/HC/CH4 oxidation, with a negligible pressure drop. The AGT adsorber includes a catalyst coating having a nanotube structure (e.g., a uniform nanostructure forest coating) or a uniform porous nanostructure of various low-cost oxides through scalable low temperature solution processes, including oxides of Ti, Cu, Ba, Mn, Zr, Zn, Sr, Ca, Li, K, Na, Al, or Ce.

Abstract: A method of capturing carbon dioxide (CO2) present in air is provided. The method includes adding a carbon-dioxide-capturing device to a heating, ventilation, and air conditioning (HVAC) system of a building. The carbon-dioxide-capturing device is added to one or both of an air handler and air-distribution ductwork of the HVAC system. The method further includes circulating air including carbon dioxide through the carbon-dioxide-capturing device in the HVAC system. A direct decarbonization system for capturing carbon dioxide present in air is also provided. The system includes an HVAC unit, air-distribution ductwork connected to the HVAC unit, and a carbon-dioxide-capturing device disposed in one or both of the HVAC unit and the air-distribution ductwork. Carbon dioxide gas present in air passing through the HVAC unit or the air-distribution ductwork is removable from the air by the carbon-dioxide-capturing device.

Abstract: A process for capturing carbon dioxide (CO2) present in a gas stream is provided. The process includes providing a cooling tower that treats a gas stream. The gas stream including CO2 is introduced into the cooling tower. A liquid carbon-dioxide-capturing media is released into the gas stream in the cooling tower. The carbon-dioxide-capturing media absorbs the CO2 in the gas stream, and the carbon-dioxide-capturing media including the absorbed CO2 is collected. An absorber for capture of CO2 in a gas stream is also provided. The absorber includes a cooling tower for treatment of a gas stream including CO2. The cooling tower includes an input for the gas stream, an outlet for a treated gas stream, and a sprayer that releases liquid carbon-dioxide-capturing media into the cooling tower. The carbon-dioxide-capturing media absorbs the CO2 from the gas stream in the cooling tower. A collector collects the carbon-dioxide-capturing media including absorbed CO2.

Abstract: A method for fabricating heat exchangers using additive manufacturing technologies. Additive manufacturing enables the manufacture of heat exchangers with complex geometries and/or with internal and external integral surface features. Additive manufacture also facilitates the manufacture of heat exchangers with regional variations, such as changes in size, shape and surface features. In one embodiment, the present invention provides a heat exchanger with a helicoidal shape that provides axial elastic compliance. In one embodiment, the internal channel of the heat exchanger varies along its length. The internal channel may have a cross-sectional area that increases progressively from one end to the other. In one embodiment, the external shape of the tubular structure may be non-circular to optimize heat transfer with an external heat transfer fluid. In one embodiment, the present invention provides a heat pipe with an internal wicking structure formed as an integral part of the additive manufacturing process.

Abstract: A medium for energy storage includes a plurality of capsules. Each capsule contains a phase changing material (PCM) configured to undergo a liquid-solid phase transition at a solidification temperature, TS. The PCM undergoes a relative volume change due to the phase transition. A shell is filled with the PCM. The shell contains a first heat-conducting material, and is configured to comply to the relative volume change. The relative volume change is configured to cause a buoyancy force, which acts on the capsule when the capsule is disposed in water at a water temperature, TW, to be larger than the capsule's weight for Tw>Ts, and equal to or smaller than the capsule's weight for Tw<Ts. The Ts can be within ±5° F. of a design water temperature To at the outlet of a water tank. The capsule can be neutrally buoyant in water at To.

Abstract: A heat exchanger apparatus includes a tube having a wall with an inner surface and an outer surface. The tube is configured to receive heat exchange fluid at one end, and output, when heated through the wall, vapor of the heat exchange fluid at the opposing end. A first layer of thermally conductive porous material is disposed on the inner surface of the tube. Heating equipment, a heat exchanger, and a method of heating are also disclosed.

Abstract: An improved method and system for treating flue gases from a natural gas furnace are provided. The method and system include an acidic gas trap (AGT) adsorber which enables the continuous adsorption and storage of SOx, NOx redox, and formic acid/CO/HC/CH4 oxidation, with a negligible pressure drop. The AGT adsorber includes a catalyst coating having a nanotube structure (e.g., a uniform nanostructure forest coating) or a uniform porous nanostructure of various low-cost oxides through scalable low temperature solution processes, including oxides of Ti, Cu, Ba, Mn, Zr, Zn, Sr, Ca, Li, K, Na, Al, or Ce.

Abstract: A method for fabricating heat exchangers using additive manufacturing technologies. Additive manufacturing enables the manufacture of heat exchangers with complex geometries and/or with internal and external integral surface features. Additive manufacture also facilitates the manufacture of heat exchangers with regional variations, such as changes in size, shape and surface features. In one embodiment, the present invention provides a heat exchanger with a helicoidal shape that provides axial elastic compliance. In one embodiment, the internal channel of the heat exchanger varies along its length. The internal channel may have a cross-sectional area that increases progressively from one end to the other. In one embodiment, the external shape of the tubular structure may be non-circular to optimize heat transfer with an external heat transfer fluid. In one embodiment, the present invention provides a heat pipe with an internal wicking structure formed as an integral part of the additive manufacturing process.

Abstract: Improved heat exchangers according to several embodiments are provided. The heat exchangers provide improved heat transfer for air flow in wet and dry operating conditions, while minimizing pressure drop across the heat exchanger in some applications. According to one embodiment, an improved heat exchanger includes a plurality of metal foam fins between adjacent heat exchange conduits, the heat exchange conduits being arranged parallel to each other to define parallel flow paths between an inlet header and an outlet header. The metal foam fins occupy a cross-flow region between adjacent conduits, the fins having a fixed angular orientation or being rotatable in unison to vary the thermal capacitance of the heat exchanger.