Abstract: A system and method are provided for storing and recovering electricity generated from conventional/renewable energy sources. A thermal energy storage vessel contains thermal storage fluid (“TSF”) comprising a eutectic ternary nitrate molten salt, induction heating elements, turbine pumps, a heat exchanger, and various data acquisition sensors like thermocouples and thermistors. The immersion heating elements receive the electricity generated from conventional and/or renewable energy source to heat the eutectic ternary nitrate molten salt to the desired temperature. Coiled tubing is deployed within the thermal containment vessel to be distribution systems for the power cycle working gas and heat exchange for the power cycle working gas. The power cycle working gas is delivered under pressure to a steam turbine. The turbine converts the energy into mechanical shaft work to drive an electricity generator to produce electricity.

Abstract: The disclosure provides a high-efficiency heat exchanger for a temperature control system of a fuel cell and a processing device thereof. The processing device includes a frame body and a power box. A bottom of the frame body is fixed to the ground by screws, and the power box is arranged at a side of the frame body for intelligent control. A displacement screw is arranged on a top of the frame body, and a sliding block driven by electricity is arranged on a surface of the displacement screw. Two ends of the displacement screw are respectively provided with a limit switch for controlling a limit position of the sliding block. A drive motor is arranged on a surface of the sliding block, and a displacement sensor is arranged on one side surface of the sliding block.

Abstract: Technologies are disclosed herein for a thin heat exchanger through which coolant may be pumped. The heat exchanger may include an envelope and a heat conduction layer provided over the envelope. The envelope may include one or more channels formed therein. The channels formed between the envelope and the conduction layer may extend the length of the heat exchange layer and be configured to carry coolant therethrough. The heat exchange layer may include an inlet manifold on a first end and an outlet manifold on another end opposing the first end. The inlet manifold may allow the flow of coolant into the heat exchange layer and the outlet manifold may allow the removal of the coolant from the heat exchange layer. Coolant flow may be controlled by a suction pump operating under computer control based at least in part on sensor data.

Abstract: A solar powered boiler assembly for producing steam with solar energy includes a bowl that is positioned in the ground. A boiler is positioned in the bowl and the boiler has a fluid therein. A dome is removably positioned on the bowl. A plurality of lenses each extends through the dome such that each of the lenses is exposed to sunlight. Each of the lenses focuses the sunlight onto the boiler to heat the boiler. In this way the boiler produces steam by heating the fluid therein. A reflector is coupled to the dome and the reflector is comprised of a light reflecting material for reflecting sunlight onto the lenses.

Abstract: Methods, apparatuses, and systems are disclosed for manufacturing a structure having layers that may operate in low pressure or vacuum environments. More particularly, methods, apparatuses, and systems are disclosed for minimizing the effects of voids by eliminating their contents in layers of bonded structures. In some implementations, a method for improving bonding within a layered structure comprises applying a bonding material layer to a substrate layer; disposing a wicking material in the bonding material layer, said wicking material having an outer surface; applying a surface material layer to the bonding material layer to form a layered structure; and curing the layered structure.

Abstract: The invention relates to a segment of a solar collector extending in a longitudinal direction, said segment being provided with a plate arrangement having a two-dimensional upper side on which a reflective layer is arranged. A plurality of rib elements are arranged on a lower side of the plate arrangement, each rib element extending transversely to the longitudinal direction of the solar collector. At least one rigidifying element, preferably at least one brace element, extends in the longitudinal direction of the solar collector, connecting the rib elements.

Abstract: Disclosed is a flexible organic light emitting display panel in which an upper substrate is larger in size than a lower substrate including a pad area. The flexible organic light emitting display panel includes, for example, a lower substrate, including a flexible lower base film and an organic light emitting diode (OLED) included in the flexible lower base film, and an upper substrate including a flexible upper base film and a multi-buffer which is coated on the flexible upper base film for preventing penetration of water.

Abstract: A simple and portable solar heat collector has a sheet of solar reflectors, each of the solar reflectors having a focal point, and tubing for routing heat absorbing fluid through the focal point of at least some of the solar reflectors. The tubing has an input tube for receiving heat absorbing fluid and an output tube for outputting heated heat absorbing fluid. The sheet of solar reflectors may have a sun-facing side and a non-sun-facing side. A first part of the tubing is adjacent to the non-sun-facing side of the sheet of solar reflectors, and a second part of the tubing extends from the first part of the tubing through holes in the sheet of solar reflectors to the focal point of at least some of the solar reflectors.

Abstract: Method and apparatus for a solar energy generating system to provide electricity to a structure ranging from a single family dwelling to multi-unit dwellings to commercial buildings, or a power plant or power grid. The system includes a solar collector having a magnifying lens to direct and focus sun rays to a solar energy collector, a heat transfer unit, boiler, a water heater backup system, a condenser unit and steam engine, and plural electrical energy storage units to store and dispense electricity to the selected type of electricity user.

Abstract: The present application relates to a solar array field (100) having an improved configuration, comprising a plurality of vacuum solar thermal panel (1) and a hydraulic circuit (10) for circulating a heat transfer fluid, said hydraulic circuit (10) comprising at least one circulation path (13, 14, 15, 16) connecting a low-temperature inlet (11) to a high-temperature outlet (12), said circulation path (13, 14, 15, 16) comprising a forward portion (15) successively traversing a plurality of vacuum solar thermal panels (1); said circulation path (13, 14, 15, 16) further comprising a return portion (16) connected downstream to said forward portion (15), said return portion (16) traversing the same vacuum solar thermal panels (1) in reverse order.

Abstract: Systems and methods for solar fluid heating in a multi-story building. A system in accordance with an aspect of the present disclosure includes solar collectors installed in solar-facing walls of the multi-story building, in which fluid receives thermal energy from the solar collectors. The system also includes fluid storage vessels. The system further includes a circulating pump coupled to the solar collectors to circulate the heated fluid between the solar collectors and the fluid storage vessels on a floor of the multi-story building.

Abstract: The present invention relates to a solar energy collector (18) including an outer casing (20) having at least one aperture (22) disposed therein and an absorber (24) disposed within the outer casing (20). The aperture (22) is arranged to receive a beam (16) of solar radiation therethrough so that the beam (16) is incident on the absorber (24). The absorber (24) is arranged in use to absorb the energy of the beam of solar radiation and to thereby convert solar radiation to heat energy to heat a fluid communicated through the absorber (24). The absorber (24) is arranged to be moved by a moving means to promote even heating of the absorber (24).

Abstract: A direct flow solar collector and solar hot water system are presented wherein high pressure connections are eliminated to lower installation costs while freeze and stagnation protection is provided by a cooling loop and a continuous circulation protocol. A novel fin design and a modular concept deliver manufacturing, shipping and assembly efficiencies while providing flexibility for customizing the collector configuration.

Abstract: A solar collection system is described that includes an elongate central truss angled upward from ground horizontal and mounted on a plurality of ground support legs, a collector subsystem mounted at one end of the central truss, a cross truss perpendicular to the central truss and mounted at an end of the central truss opposite the collector subsystem, and a reflector subsystem mounted on the cross truss. The collector subsystem includes a truncated trapezoid-shaped housing with a front side facing the reflector subsystem, the front side including a glassed-in opening fronting a V-shaped core heat mechanism enclosed within the housing interior that captures reflected photon energy from the reflector subsystem which heats a fluent medium within the V-shaped core heat mechanism for output to an external source for thermal power operations.

Abstract: A solar water heating system, including: (a) a solar heating collector, having: (i) an array of convex lenses; (ii) a panel disposed below the array of convex lenses, wherein the array of convex lenses focuses sunlight on the panel to heat areas of the panel; (iii) a fluid chamber disposed below the panel; and (iv) a plurality of members extending from the panel into the fluid chamber to transfer heat from the panel into fluid in the fluid chamber; (b) a fluid reservoir; (c) a fluid inlet line for moving fluid from the fluid reservoir into the fluid inlet of the solar heating collector; (d) fluid outlet line for moving fluid from the fluid chamber of the solar heating collector to the fluid reservoir; and (e) a pump for moving fluid cyclically through the fluid chamber of the solar collector and the fluid reservoir.

Abstract: A solar array is provided with a first heat-transfer fluid transporting line (parabolic trough loop) for transporting a first heat transfer fluid, and at least one further heat-transfer fluid transporting line for transporting a further heat transfer fluid arranged to receive solar energy from, for example, a parabolic-trough solar array. The first heat-transfer fluid transporting line and the further heat-transfer fluid transporting line are coupled to form an overall heat-transfer fluid transporting line (for example, as a parabolic trough loop). The first heat-transfer fluid transporting line is connected to at least one main line pump for pumping the first heat transfer fluid through the heat-transfer-fluid transporting line and the further heat-transfer fluid transporting line is connected to at least one further main line pump for pumping the further heat transfer fluid through the further heat-transfer-fluid transporting line. The first and further heat-transfer fluids may be the same fluid.

Abstract: A thermoregulation apparatus for a solar thermal energy capture system comprising a piping infrastructure in fluid communication with a fluid storage tank and one or more solar thermal energy collectors. The thermoregulation apparatus comprises: (i) a thermostatically actuated valve interposed the piping infrastructure downstream from the one or more solar energy collectors and upstream from the fluid storage tank, and (ii) piping for interconnecting the thermostatically actuated valve with the piping infrastructure, and the fluid storage tank. The thermostatically actuated valve can be configured for diverting the flow of working fluid away from the fluid storage tank when the temperature of the working fluid is below a selected set point for actuating the valve, and for diverting the flow of working fluid to the fluid storage tank when the temperature of the working fluid is about or greater than the selected set point.

Abstract: A method for operating a directly heated, solar-thermal steam generator is provided. As per the method, a nominal value Ms for the supply water mass flow M is conducted to an apparatus for adjusting the supply water mass flow M wherein, at the adjustment of the nominal value Ms for the supply water mass flow M, account is taken of a correction value KT, by which the thermal effects of storage or withdrawal of thermal energy in an evaporator are corrected.

Abstract: A drainback tank having a solar return pipe, at least a portion of the solar return pipe being located within the internal body of the tank, the solar return pipe having a hole that is in close proximity to the hole of an output pipe, such that the fluid in the solar return pipe flows into the output pipe and leaves the tank housing to be used to heat the fluid of a corresponding hot water tank via convection in a heat exchanger.

Abstract: A startup system for a solar boiler includes a main fluid circuit having a plurality of solar boiler panels for generating power from solar energy. An auxiliary fluid circuit is selectively connected in fluid communication with the main fluid circuit by a plurality of valves. An auxiliary boiler is operatively connected to the auxiliary fluid circuit. The valves connecting the auxiliary fluid circuit to the main fluid circuit are configured to be opened and closed to selectively place the auxiliary boiler in fluid communication with portions of the main fluid circuit to supply heat to the portions of the main fluid circuit in preparation to produce power from solar energy.

Abstract: The invention relates to a solar collector (1) comprising a collector housing (2), an absorber (3) arranged therein and having a heating medium fluid (13) flowing through it, to absorb solar radiation (28), a return line (6) leading to the absorber (3) and a flow line (7) leading away from the absorber (3). Thereby a pump (14) is arranged on or at least partially inside the collector housing (2) for circulating a heating medium fluid (13) through the absorber (3).

Abstract: A roofing installation system for optimally capturing solar thermal energy comprises a plurality of metal battens mounted horizontally onto a plurality of horizontal wooden battens, a plurality of slate modules mounted on the plurality of metal battens and connected in series to form a string, an inverter connected to each string, a thermal tubing containing liquid mounted on the plurality of metal battens, a heat exchanger connected to the thermal tubing, a heat pump connected to the thermal tubing and a circulation pump connected between the thermal tubing and the heat exchanger. The plurality of slate modules generates DC electricity from solar energy and the inverter converts the DC electricity to AC electricity to feed to a utility grid. The plurality of metal battens transfers thermal energy by running liquid in the thermal tubing which is extracted by the heat exchanger thereby producing domestic hot water.

Abstract: Molten salt solar receiver and procedure to reduce the temperature gradient in said receiver. The receiver consists of at least one panel of semi cylindrical geometry, formed by a combination of vertical pipes. The receiver (10) is supplied with a heat transfer fluid made up of molten salts which originate from a recirculation system which is composed of a mixture deposit (6), a hot salt storage tank (9) and a cold salt storage tank (8); the mixture tank (6) which is supplied by a part of the hot heat transfer fluid (4) which exits the receiver (10) and the cold heat transfer fluid (5) which exits the cold salt storage tank (8); the hot salt storage tank is connected to the exit of the receiver (10) so that a part of the heat transfer fluid which does not recirculate is stored (3).

Abstract: One or more hot water solar systems or solar collection assemblies are disclosed herein. The solar collection assemblies may include an insulating support assembly for supporting a tank above a nearby ground surface. An immersion vent having improved characteristics may be provided. A BTU meter positioned within an equipment cavity and having improved characteristics may be provided. Insulated tank supports having improved characteristics may be provided. A heat exchanger to panel sizing ratio for improved performance may be provided.

Abstract: In this presentation, we have shown new methods, devices, and systems, to concentrate the light for the solar cells, using refractive index variations, light funnels, liquid crystals, and other methods and materials. We have shown various methods for enhancing the solar cell efficiency. We have given many variations for each application.

Abstract: A solar receiver has an arrangement of heat transfer surfaces and a heat transfer fluid phase separator, such as a vertical steam/water separator, fluidly interconnected thereto. The receiver includes a plurality of heat transfer fluid filled components, and at least one alternate heat source. When various temperature measurements indicate freezing or solidification of the fluid is possible, the alternate heat source is activated to maintain a temperature of the fluid greater than the freezing/solidification point of the fluid. The application of the alternate heat source further induces natural circulation of the fluid within the components, further providing freeze/solidification protection to the receiver. A controller may be configured to receive sensed temperatures of the fluid, components, ambient air, etc., and use these temperatures relative to a threshold temperature to activate, vary output, and deactivate one or more alternate heat sources.

Abstract: The invention, in some embodiments, relates to solar energy collectors, and methods of use thereof. In some embodiments, the invention relates to liquid-air transpired solar energy collectors, and methods of use thereof. In some embodiments, the invention relates to thermal energy transfer systems that comprise solar energy collectors, and methods of use thereof. In some embodiments of the invention, methods of constructing solar energy collectors are provided.

Abstract: Systems, methods, and apparatus by which solar energy may be collected to provide electricity, heat, or a combination of electricity and heat are disclosed herein.

Abstract: A solar power tower system includes a solar tower receiver, a cold storage tank and a hot storage tank at the bottom of the tower receiver with a heat transfer fluid down pipe from the receiver and a working fluid up pipe into the receiver. A potential energy recovery system is located at the bottom of the tower configured such that it recovers part of the mechanical energy of the heat transfer fluid and uses it in the pumping of the working fluid to the receiver and providing power to other equipment in the solar power tower system in any kind of energy.

Abstract: The present invention relates to a solar thermal system which has improved use efficiency, enables heat acquired in a heat-collecting unit to be quickly used for a heating and hot water supply load, and can be operated in a stable manner.

Abstract: The present invention relates to a solar energy collector (18) including an outer casing (20) having at least one aperture (22) disposed therein and an absorber (24) disposed within the outer casing (20). The aperture (22) is arranged to receive a beam (16) of solar radiation therethrough so that the beam (16) is incident on the absorber (24). The absorber (24) is arranged in use to absorb the energy of the beam of solar radiation and to thereby convert solar radiation to heat energy to heat a fluid communicated through the absorber (24). The absorber (24) is arranged to be moved by a moving means to promote even heating of the absorber (24).

Abstract: An energy collecting module for assembling, together with a plurality of similar energy collecting module, a modular energy collecting system. The energy collecting module comprises a fluid channel having a lumen for conducting fluid from a first connectable opening to a second connectable opening and an energy collecting element mounted in front of the fluid channel for concentrating radiation along the fluid channel.

Abstract: The present invention relates to a solar water heating system including: a solar collector to which solar heat is collected; a solar collector circulation pipe adapted to circulate an operating medium on which the solar heat collected by the solar collector is accumulated therealong; a thermal storage tank in which the operating medium and the water used for living are heat-exchanged; a hot water circulation pipe communicating with the thermal storage tank; a freezing prevention valve located on one side of the hot water circulation pipe and adapted to be open and closed to allow the water in the thermal storage tank to selectively flow along the hot water circulation pipe; and a controller adapted to control the operation of the freezing prevention valve, thereby preventing the hot water circulation pipe from being frozen and destructed.

Abstract: A solar cell collector unit that materially contributes to a more efficient use and conservation of green energy includes a first metal sheet having alternating corrugated crest and valley portions on an upper surface and alternating open channels on an under surface and having a first dimension with a first peripheral edge about its entire perimeter. A second substantially flat metal sheet having a second dimension with a second peripheral edge about its entire perimeter and less than the first dimension. The first and second metal sheets overlie one another with flattened copper tubing disposed within the open channels and sandwiched there between, while crimping and folding the first peripheral edge over the second peripheral edge to form nested protuberances about its perimeter to provide stiffness and rigidity there about and forming a low cost single solar cell unit.

Abstract: A thermal absorber including a light-transparent reservoir having an alkali metal received therein, a housing sealingly coupled to the reservoir to define an enclosed volume, the housing including a thermal barrier wall that divides the volume into a cold chamber and a hot chamber, the cold chamber including a sump having a drain hole in fluid communication with the hot chamber, and at least one AMTEC cell supported by the cell supporting surface, the AMTEC cell extending through the cold chamber and the hot chamber.

Abstract: Solar energy conversion systems and methods use solar collectors and working fluid management systems to provide both efficient and safe operation under a wide range of operating conditions. In one embodiment, a solar collector and at least one fluid accumulator preferably with an integral heat exchanger, and at least two mass flow regulator valves enable working fluid flow into and out of the fluid accumulator.

Abstract: A reflector to reflect solar radiation, the reflector having a concave reflector surface, wherein the surface curves about a first axis and a second axis, the second axis being in a plane generally normal to the first axis and curved about the first axis. Also disclosed is an apparatus for collection and utilization of solar energy including at least one of the reflectors, and at least one photovoltaic cell associated with each surface and positioned relative to the associated surface so as to be positioned to receive radiation reflected by the associated surface and to convert the radiation to electrical energy. The apparatus further includes heat a conversion mechanism for converting excess solar radiation energy incident thereon to heat energy.

Abstract: The invention provides a system for collection of thermal energy. The system comprises an energy collector, an energy reservoir, an energy collection medium enclosed in a loop allowing fluid flow of the energy collection medium between the energy collector and the energy reservoir in a forward flow from the energy collector and in a backward flow to the energy collector for transferring energy between the energy collector and the energy reservoir, a collector pump adapted to control a flow rate of the energy collection medium, and a reservoir temperature measuring device being adapted to measure a reservoir temperature of the energy reservoir.

Abstract: A solar heating system and a method for controlling the system, the system including at least two solar collectors with different exposure, a load, a main supply line which branches into individual supply lines to the solar collectors, and a main return line into which lead individual return lines from the solar collectors, a distribution valve which is arranged at the branch-off of the main supply line to the individual supply lines or at the branch-off of the main return line to the individual return lines, and a pump for conveying a heat transfer medium.

Abstract: A solar collection system is described that includes an elongate central truss angled upward from ground horizontal and mounted on a plurality of ground support legs, a collector subsystem mounted at one end of the central truss, a cross truss perpendicular to the central truss and mounted at an end of the central truss opposite the collector subsystem, and a reflector subsystem mounted on the cross truss. The collector subsystem includes a truncated trapezoid-shaped housing with a front side facing the reflector subsystem, the front side including a glassed-in opening fronting a V-shaped core heat mechanism enclosed within the housing interior that captures reflected photon energy from the reflector subsystem which heats a fluent medium within the V-shaped core heat mechanism for output to an external source for thermal power operations.

Abstract: A light absorbing device for heating a medium by means of solar energy, comprising a first and second layer of which at least one is intended for solar energy absorption, forming a space there between in which a first medium is arranged to flow for said heating, and means arranged to allow said flowing, wherein at least one of said layers is flexible such that the surface exposed for solar energy absorption is reducible. The invention also relates to an at least partly flexible building construction.

Abstract: A solar panel comprises a conduit which in the usual way is designed to comprise a heat carrying medium for heat transfer between the solar panel and the surrounding environment. The conduit is placed so that it can be heated by the rays from the sun. The solar panel comprises a chemical heat pump of the type hermetically sealed unity tube with a reactor part, an evaporator/condenser part and a passage there between. The part of the unity tube comprising the reactor part of the chemical heat pump is positioned in heat conducting contact with the first conduit and thereby the part of the unity tube with the reactor part will be heated. The unity tube may be surrounded by a heat insulating part of vacuum jug type comprising an evacuated space between an outer wall and an inner wall. The inner wall may at its outwards facing surface comprise a radiation receiving part adapted to transform solar radiation to heat and which is in heat conducting contact with the first area and the first conduit.

Abstract: Apparatus to collect solar radiation using a series of lenses or mirrors that concentrate the solar energy onto targets. A gaseous working fluid flowing through the targets is heated and optionally supplied to a heat store having an internal walled labyrinth of a suitable material to store heat energy. A heat exchanger, turbine and electricity generator are coupled to the collection and storage apparatus so as to provide a power plant for the conversion of solar energy to electricity.

Abstract: Heat transfer fluid in vapour only state is cycled through solar collector(s) (12) and a sensible heat storage medium (14) to transfer heat from the solar collector(s) (12) to the sensible heat storage medium (14). The heat transfer fluid is a liquid at ambient temperature, but substantially in the vapour state throughout the entire cycle when in operation.

Abstract: A pump drained solar water heating system, includes a solar collector; a reversible pump; a reservoir for storing heat transfer fluid; an insulated water storage tank for storing the potable water; piping for fluidically connecting the pump to the solar collector, the heat transfer fluid reservoir; and a heat exchanger; and a controller for operating the pump to transmit fluid in a forward flow or reverse flow direction.

Abstract: The invention relates to a solar receiver with natural circulation for generating saturated steam, which uses water/steam as a heat-transfer fluid and includes a combined circuit for fluid recirculation (forced circulation and natural circulation). The system comprises: water-walls which receive the radiation on the surface thereof and inside which the working fluid changes phase; riser pipes through which the water/steam mix exiting the pipes of the receiver rises towards the boiler; downpipes through which the recirculation water descends from the boiler to the receiver; and a support pump in order to increase the incident power in the receiver and start up the plant when necessary.

Abstract: A solar thermal panel is disclosed. An example evacuated flat solar thermal panel includes a first evacuated cavity enclosed between first and second layers of material. A second evacuated cavity is enclosed between third and fourth layers of material. A high temperature working fluid cavity is enclosed between the second and third layers of material. A plurality of pillars are disposed between the first and second layers of material, and disposed between the third and fourth layers of material.

Abstract: A dual hybrid heating apparatus, method of assembly and operation to heat potable water in a tank by heat exchange with a fluid heated by free heat sources—waste heat from heat recovery units and insolation. Once a demand for heated potable water is satisfied, a controller issues commands that cause the fluid to bypass the tank and instead flow to a further heat exchanger. Temperature is monitored downstream—if excessive, then the fluid is sent to a heat dump. A further fluid is heated by heat exchange at the further heat exchanger and then routed to where a parabolic dish solar concentrator vaporizes it to turn a blade of a turbine generator to generate electricity. Heat is extracted from the vapor to form condensate, but the vapor also heats the condensate before being cooled by heat exchange with fluid cooled by a cooling tower.

Abstract: A hot blast heater capable of heating air using solar energy and providing hot air for daily life is provided. The hot blast heater includes a chamber, a lifting part, a control part and a pump. The chamber is configured to form an accommodation space to accommodate air, has an inlet/an outlet which are formed through a lower part and an upper part of the chamber, respectively, such that indoor air is received through the inlet and air inside the chamber is discharged through the outlet, and is formed using light passing material or thermal conductive material. The lifting part is installed lengthwise along two facing sides of the window to lift the chamber such that the air inside the chamber is heated through sunlight or solar heat introduced through the window. The control part controls operations of the lifting part. The pump is installed at the outlet of the chamber to forcedly discharge the heated air inside the chamber to an indoor space.

Abstract: A solar water heating system, including: (a) a solar heating collector, having: (i) an array of convex lenses; (ii) a panel disposed below the array of convex lenses, wherein the array of convex lenses focuses sunlight on the panel to heat areas of the panel; (iii) a fluid chamber disposed below the panel; and (iv) a plurality of members extending from the panel into the fluid chamber to transfer heat from the panel into fluid in the fluid chamber; (b) a fluid reservoir; (c) a fluid inlet line for moving fluid from the fluid reservoir into the fluid inlet of the solar heating collector; (d) fluid outlet line for moving fluid from the fluid chamber of the solar heating collector to the fluid reservoir; and (e) a pump for moving fluid cyclically through the fluid chamber of the solar collector and the fluid reservoir.