Abstract: A three-dimensional (“3D”) printer.

Abstract: A trough for cooling and delivering molten metal to a casting station. The trough comprises a refractory portion for holding the molten metal and heat transfer means associated to external walls of the refractory portion for extracting heat from the molten metal. The heat transfer means may comprise a fluidized bed compartment for holding and fluidizing a fluidization material. Also, the heat transfer means may comprise a cooling jacket, an inner wall of the cooling jacket and the external walls of the refractory portion defining the fluidized bed compartment.

Abstract: A recovery boiler plant of a chemical pulp mill including: a boiler including a lower region with an outlet to discharge smelt; a dissolving tank proximate to the outlet and configured to receive smelt; a smelt spout coupled to the outlet and including a chute extending from the outlet to a position at or over an inlet to the dissolving tank; and a shielding room including walls, a ceiling and a floor, wherein one of the walls includes a wall of the boiler, and the shielding room encloses a volume adjacent the boiler and above the dissolving tank, wherein the enclosed volume includes and the smelt spout and a working area in front of the smelt spout.

Abstract: A snorkel nozzle (10) having a double shell core (16, 26) that defines an annular gap (40) between the shells and that has an array of baffles (66) arranged in the annular gap to define a serpentine flow path for cooling gases that pass through the annular gap.

Abstract: Devices capable of deterring or preventing bulk extraction of drugs from, for example, drug-delivery systems are exemplarily disclosed. In one embodiment, such a device may include a package releasably retaining a drug and an agent. The agent is configured to suppress a physiological effect of the drug when the agent contacts the drug or is coadministered with the drug. The cell package is configured such that an amount of the drug is selectively releasable with respect to the agent when the package is operably proximate to an encoded key. The package, however, may be configured to impose a relatively high likelihood that either the drug will not be accessed or the drug will be contaminated by the agent if access to the contents of the package is sought without the use of an encoded key.

Abstract: A snorkel nozzle (10) having a double shell core (16, 26) that defines an annular gap (40) between the shells and that has an array of baffles (66) arranged in the annular gap to define a serpentine flow path for cooling gases that pass through the annular gap.

Abstract: A digital manufacturing system comprises a build chamber, a build platform disposed within the build chamber, at least one extrusion line configured to heat a metal-based alloy up to a temperature between solidus and liquidus temperatures of the metal-based alloy, a deposition head disposed within the build chamber and configured to deposit the heated metal-based alloy onto the build platform in a predetermined pattern, an umbilical having a first end located outside of the build chamber and a second end connected to the deposition head, and at least one gantry assembly configured to cause relative motion between the build platform and the deposition head within the build chamber, where the at least one gantry assembly comprises a motor disposed outside of the build chamber.

Abstract: Various non-limiting embodiments disclosed herein relate to nozzle assemblies for conveying molten material, the nozzle assemblies comprising a body, which may be formed from a material having a melting temperature greater than the melting temperature of the molten material to be conveyed, and having a molten material passageway extending therethrough. The molten material passageway comprises an interior surface and a protective layer is adjacent at least a portion of the interior surface of the passageway. The protective layer may comprise a material that is essentially non-reactive with the molten material to be conveyed. Further, the nozzle assemblies according to various non-limiting embodiments disclosed herein may be heated, and may be self-inspecting. Methods and apparatus for conveying molten materials and/or atomizing molten materials using the nozzle assemblies disclosed herein are also provided.

Abstract: The invention relates to a tapping channel (1) for a metallurgical furnace, particularly for an electro-reducing furnace, comprised of at least one tapping brick (10, 11, 12) and of a cooling device in the vicinity of the tapping channel (1). The cooling device is provided in the form of a sleeve (14), which indirectly cools a tapping brick (2) and which at least partially surrounds the furnace wall (3) in the vicinity thereof.

Abstract: An air bearing gap control arrangement for injection molded solder filler heads. Also provided is a method of providing for a gap control for injection molded solder filler heads utilizing an air bearing arrangement. Provided is a C-ring seal, at the lower or dispensing region of the solder filler head structure, wherein the C-shape is open at the leading edge thereof. Hereby, a prevalent leading edge gap is tightly controlled by means of pressurized air in order to form an air bearing. Downstream of this leading edge is the molten solder, which is contained within a very narrow gap height between the solder filler head and the mold. As the solder fills the pits or recesses which are formed in the mold surface, air will rush out or be displaced from the pits towards the air bearing and is then expelled, while the deposited solder remains in place.

Abstract: This invention discloses a molten metal supply system that can supply molten metal to a downstream process at a constant pressure and molten metal flow rate. The molten metal supply system includes a molten metal supply source, a plurality of injectors, and a plurality of check valves.

Abstract: The invention pertains to a process and an apparatus for the discontinuous tapping of melts. An inductor surrounds a passage through which the melt is discharged from a vessel. The inductor applies radial electromagnetic energy to the passage to maintain the melt in a molten state. To stop flow of the melt through the passage, an outlet opening of the passage is closed and the inductor is electrically switched off while a cooling medium is flowed through the inductor. To begin flow of the melt, the outlet opening of the passage is opened and the inductor is electrically switched on.

Abstract: A nozzle for thin strip casting plants, especially for steel strip. In casting plants of this type, the liquid steel must be applied on a carrier from the nozzle forming a casting gap. At least one primary coil and a secondary coil are arranged at the nozzle, wherein the secondary coil is water-cooled and projects into the area of the casting gap.

Abstract: Tapping method for molten metal from containers (13) including at the lower part a tapping channel (14) associated at the end part with a discharge hole (15) substantially vertical or sub-vertical, the discharge hole (15) being associated at the lower part with a sliding interception device (19), wherein the tapping channel (14) comprises, associated with the walls, an electromagnetic device (17) with spirals (18) and a system for cooling the walls, wherein, during the end-of-tapping step of the liquid metal the sliding interception device (19) is activated by closing the discharge hole (15) and allowing the metal in the tapping channel (14) to solidify so as to form at least a layer which lines both the tapping channel (14) and the discharge hole (15) filling it completely, and that during the start-of-tapping step the sliding interception device (19) is activated by leaving the discharge hole (15) free and the metal which is blocking the discharge hole (15) is melted by means of the electromagnetic device (

Abstract: A refractory block for continuous casting comprising: a unitary assembly comprising: a plate brick having a top, a bottom, sides and a passageway therethrough, and a submerged nozzle having a top, a bottom, sides and a passageway therethrough, the sides of the submerged nozzle having a shoulder portion, the bottom of the plate brick joining the top of the submerged nozzle; a metal casing surrounding the unitary assembly such that the metal casing surrounds and supports a portion of the sides of the plate brick, a portion of the bottom of the plate brick and a portion of the sides of the submerged nozzle including the shoulder portion, and an air cooling jacket surrounding the metal casing.

Abstract: An apparatus for depositing a selected pattern of solder onto a substrate comprising: a substrate support having structure for bearing a substrate on which one or more electronic components are to be mounted; a solder ejector that defines a cavity for containing molten solder and an orifice for ejecting a stream of molten solder; a heater for heating the solder to a temperature above the melting point of solder; a vibrator coupled to the solder ejector to form droplets in the stream at the desired frequency for deposition onto the substrate; and a cooler, adapted to receive a coolant, disposed between the heater and the vibrator to maintain the temperature of the vibrator below that which would detrimentally affect the performance of the vibrator.

Abstract: In order to produce separate measured portions (1") of liquid solder, solid solder (1) in the form of wire or rod is guided through the longitudinal bore of a guide tube (20). A zone including the end (22) of the tube (20) is heated above the solder's melting temperature, in order to liquefy the solder. By contrast, an adjacent zone of the guide tube is cooled, whereby a positionally stable temperature transition is maintained in the tube (20). Thereby the amount of molten solder available above a narrowed outlet (62) is controlled. A drive mechanism (3) advances the solder (1) step by step so that the solid solder acts as a piston to eject portions of liquid solder through the aforesaid outlet (62). A suitable apparatus (5) for applying portions of solder to a substrate (4) can be raised and lowered (a). At its base it has a moulding die (6) connected to the outlet (62) that can be set down upon the substrate and has a moulding cavity open on its underside.

Abstract: A cooled elongated, preferably threaded and, tapered, metallurgical taphole plug and a method for using it are described. The plug is inserted into a taphole to cause a plug of molten material to freeze in the taphole such that molten material flow within the taphole is stopped. In one embodiment, the plug is comprised of an externally threaded, elongated member having a first end and a second end with a taper extending at least partially therebetween. The first, narrower end, which is inserted into the taphole, is cooled by a fluid flowing through an internal passage extending at least partially between the first and second ends. As the first end is cooled, the molten material adjacent the first end freezes around the tip of the first end, effectively plugging the taphole. The device is removed by discontinuing fluid flow and applying a rotational moment about the second end such that the threaded, tapered device backsout of the taphole.

Abstract: A segmented smelt spout comprising an assembly of different casting shapes wherein one shape constitutes the base segment, which is installable in a chemical recovery unit, and the other shapes are a combination of straight and curved cast segments, which can be used in different combinations to obtain varying spout angles and lengths with the latter segments being supported off the base segment and being held together by a tensioning means that maintains contact between the mating surfaces of each segment while permitting each individual segment to expand and contract thermally.

Abstract: The invention relates to an apparatus for the suspension smelting of sulfidic, finely divided raw materials containing metals, such as copper, nickel and lead, by using oxygen enrichment. In this method into the suspension smelting furnace (1) there is fed the raw material (4,5) to be smelted together with flux (6) and oxidizing gas (7) and the walls (18) of the reaction space of the suspension smelting furnace are cooled and at least two molten phases created (16,17). According to the invention the degree of oxygen enrichment of the oxidizing gas is at least 40% in order to raise the temperature of the particles in suspension to at least 200.degree. C.

Abstract: A liquid metal electromagnetic pump 17 operates by passing an electric current through the liquid metal in a direction transverse to an applied magnetic field and the longitudinal axis of the liquid metal flow pipe. The direction of the pump is reversible by reversing the electric current. It is used to transfer batches of contaminated solder from a reservoir 12 in a hot air solder leveller 11 to a treatment tank (TA or TB). Contamination of the solder is removed by a cleaning process and the liquid solder returned to the reservoir 12 after heating to the required process temperature.

Abstract: A smelt spout for a chemical recovery furnace comprises a trough of U-shaped profile fabricated as a casting in a nickel-chromium alloy containing a minor amount of niobium. A system incorporating the spout includes a cooling arrangement which delivers cooling air to the outside surface of the spout.

Abstract: A method of electroslag refining of metal is taught. The method includes the introduction of unrefined metal into an electroslag refining process in which the unrefined metal is first melted at the upper surface of the refining slag. The molten metal is refined as it passes through the molten slag. The refined metal is collected in a cold hearth apparatus having a skull of refined metal formed on the surface of the cold hearth for protecting the cold hearth from the leaching action of the refined molten metal. A cold finger bottom pour spout is formed at the bottom of the cold hearth to permit dispensing of molten refined metal from the cold hearth.

Abstract: In tapping method in which molten iron (16) and molten slag (18) are discharged from a blast furnace, a conducting pipe (30) is connected to the external side of a molten iron taphole (12), and an electromagnetic energy supply body (32) is disposed around the outer periphery of the conducting pipe (30), whereby a turning motion or a magnetic pressure due to an electromagnetic repulsive force to the molten iron flowing in the conducting pipe (30) for separating the molten iron (16) from the molten slag (18) thus controlling the discharge rates thereof. With this tapping method, it becomes possible to keep substantially constant the discharged amounts of molten iron and molten slag from the blast furnace during a period from the starting to the completion of the tapping and significantly reduce the number of drilling/blocking upon tapping, and hence to stabilize quality of products and save the tapping work.

Abstract: Device for the extraction by pouring at a regulatable flow rate a molten material in a cold structure melter. The melter has at least one part of a floor around a pouring orifice cooled by a flow of water and a heat source able to melt the material to be melted. An orifice is provided in the floor of the melter, whose diameter D is equal to or larger than the thickness H of the wall forming the melter. A metal sleeve is provided, whose base has a shoulder which can be adapted to the side walls of the orifice. The sleeve has a central passage forming the pouring tube for the molten material and a clearence is provided between the side walls of the orifice and the base of the sleeve in order to receive an insulating material between the sleeve and the cold floor of the melter. A device is provided beneath the floor of the melter having a cooled, sliding blade, equipped with an actuator controlling its movement in translation along the orifice, thus determining its more or less large opening or closing state.

Abstract: A spout for channeling smelt from a boiler through an opening in the walls of the boiler comprises a jacket having an inner wall and an outer wall. The outer wall is spaced a distance away from the inner wall and the jacket has one end insertable into the opening of the wall. The jacket defines a trough for carrying smelt from the boiler. An inlet communicates with the jacket for delivering a water flow to the jacket between the inner wall and the outer wall. An O-shaped tube communicates with the jacket at the inserted end of the jacket for receiving the water flow from between the inner wall and the outer wall of the jacket. An outlet communicates with the O-shaped tube near the inserted end for channeling the water flow from the O-shaped tube and out of the spout. A vacuum is used near the outlet for insuring a proper low pressure drop.

Abstract: A cooling member for positioning in the refractory wall of a cupola at a location spaced from a tap-hole has a heat-conductive member, such as a copper plate, in contact with a fluid-conducting member, such as a copper conduit. The cooling member is bent to form an L-shaped member, so that a pair of such members defines a channel at the tap-hole location. Refractory is provided on each side of the L-shaped member and forms the tap-hole on the interior within the channel thus formed. Alternative shapes for the cooling member are disclosed.

Abstract: A method for the electroslag refining of metal is provided. The method involves providing a refining vessel to contain an electroslag refining layer floating on a layer of molten refined metal. An ingot of unrefined metal is lowered into the vessel into contact with the molten electroslag layer. A refining current is passed through the slag layer to the ingot to cause surface melting at the interface between the ingot and the electroslag layer. As the ingot is surface melted at its point of contact with the slag, droplets of the unrefined metal are formed and these droplets pass down through the slag and are collected in a body of molten refined metal beneath the slag. The refined metal is held within a cold hearth. At the bottom of the cold hearth, a cold finger orifice is provided to permit the withdrawal of refined metal from the cold hearth apparatus. The refined metal passes from the cold finger orifice as a stream and is processed into a sound metal structure having desired grain structure.

Abstract: An apparatus that controls the flow of a stream of metal, such as produced from the bottom of a hearth, includes a cylindrical metallic nozzle body having a hollow wall which includes a slit extending substantially parallel to the axis of the cylinder so that there is no electrical continuity around the nozzle wall across the slit. The walls of the cylinder are preferably formed of hollow tubes through which cooling water is passed. A sensor senses a performance characteristic of the apparatus, such as the temperature of the nozzle body. An induction heating coil surrounds the nozzle body, and a controllable induction heating power supply is connected to the induction heating coil to provide power. A controller controls the power provided to the induction heating coil by the induction heating power supply responsive to an output signal of the sensor, so that a selected performance characteristic of the apparatus may be maintained.

Abstract: A fixed plate member, and a movable plate member is mounted against the fixed plate member. The fixed plate member consists of a fixed metal support plate having a plane outer metal surface and a cutout in which is accommodated a wear part made of refractory material which is pierced with at least one pouring orifice. The lower refractory surface of the refractory wear part is flush with the plane outer metal surface of the fixed metal support plate. The major portion of the rubbing surface of the fixed plate member and contact with the movable plate member consists of only the plane outer metal surface, while only the remaining minor portion consists of the lower refractory surface of the wear part.

Abstract: A nozzle assembly design and a method for making the nozzle assembly, as well as a method for controlling a continuous skull nozzle process employing the nozzle assembly are provided wherein the cooling heat transfer coefficient at the nozzle is increased to maintain a steady-state solidified layer of a noncontaminating liner material, the cooling heat transfer coefficient being increased by reducing the contact resistance between a nozzle outer wall member and an inner liner made of the noncontaminating material, the reduction in contact resistance being achieved by shrink-fitting the nozzle outer wall member around the inner liner to increase the contact pressure between those members.

Abstract: Apparatus for constraining the flow of molten metal from a tundish to a mould along the inner periphery of a tube mounted between them. A vertically movable stopper rod is seated at its lower end in a nozzle at the entrance to the tube the end being so designed as to cause an annular discharge of metal into the tube upon the stopper rod lifting from its seating, gas being injected through the stopper whereby to generate a gaseous void within the interior of the tube to promote the maintenance of the metal flow path of along the length of the inner periphery of the tube.

Abstract: A nozzle assembly is shown for depositing solder onto a series of conductive surfaces such as the mounting pads of a surface mount integrated circuit board. The nozzle assembly includes a nozzle head which has an interior bore for receiving an elongate heat source. The nozzle head also includes an orifice for receiving solid solder fed within the interior bore to contact the elongate heat source. The interior bore terminates in a solder reservoir for molten solder which is fed within the inteiror bore to contact the elongate heat source. The molten solder is dispensed through a tip opening to deposit uniform amounts of solder on each pad. A source of bleed gas is supplied to the interior of the assembly to protect the component parts and excluse oxygen from the interior of the assembly. A cover gas is also supplied to the solder site to reduce oxidation of the moltent solder and reduce the amount of flux required.

Abstract: A nozzle assembly is shown for depositing solder onto a series of conductive surfaces such as the mounting pads of a surface mount integrated circuit board. The nozzle assembly includes an upper nozzle mount and a removeable nozzle head which has an interior bore for receiving a portion of the nozzle mount and an elongate heat source. The nozzle head also includes an orifice for receiving solid solder fed within the interior bore to contact the elongate heat source. The interior bore terminates in a solder reservoir for molten solder which is fed within the interior bore to contact the elongate heat source. The molten solder is dispensed through a tip opening to deposit uniform amounts of solder on each pad.

Abstract: The invention relates to a method and apparatus for controlling the temperatures of a plurality of zones of a casting hearth or vessel. The invention also relates to a method for controlling the thickness of the solidified skull of castable material in the casting hearth or vessel. By the present invention, the efficiency of the skull casting process can be significantly improved by reducing the thickness of the skull and thereby increasing the amount of castable material which can remain molten and pourable.

Abstract: A heat transfer conduit for extracting heat from a molten metal in transit from a containing vessel or delivery system includes at least two elongate segments separable along separation lines which lie generally in the direction of a longitudinal center line of the conduit, which in use, define a unitary structure. The segments can be disassembled following use for the removal of solidified material and other matter from the conduit interior.

Abstract: The cooling device comprises a supply chamber disposed around a vertical duct and having a front wall which at a spacing intimately follows the shape of the vertical duct, and an evacuation chamber disposed around the supply chamber and separated therefrom by an intermediate wall. The front wall is formed with a number of passages extending towards the vertical duct. Some of these passages open into the supply chamber and the remainder of the passages are connected to tubes which extend through the supply chamber and the intermediate wall and open into the evacuation chamber. The supply chamber comprises means for supplying cooling liquid, and the evacuation chamber comprises means for evacuating cooling liquid.

Abstract: An integral transfer tube is produced comprised of a hollow high density ceramic oxide tube having its outer surface wall surrounded by a low density multilayered ceramic oxide shell, and having a heating element comprised of a heating wound portion and two end portions wherein the wound portion is intermediate the tube and the shell, and wherein at least a sufficient amount of the end portions are exposed for electrical attachment.

Abstract: A method and apparatus for casting a grain refined ingot from a metallic melt supplied to a casting mold through a feed tube. The feed tube is provided with at least one cooling passageway through which a cooling fluid cyclically flows to form a zone of fine dendrites on the inner peripheral surface of the mold. An inductor is provided to reheat the zone of fine dendrites to detach dendrite arms into the melt which serve as nuclei for grain refinement as the melt solidifies into a cast ingot in the mold.

Abstract: Melt flows down through downspouts into a basin defined by a pair of cooling rolls and side dams. Melt is decreased in flow rate to be supplied uniformly through a slit nozzle in a widthwise direction of the cooling rolls so that a solidified shell formed over the cooling rolls can be prevented from being melted again.

Abstract: A ladle for casting molten metal comprising an inner nozzle forming a casting channel and a ladle closing device comprising a fixed element and a moving element, the inner nozzle being surrounded by an annular cooling chamber along part of its length. The annular chamber (3) contains an annular ring (5), the interior of which communicates with a duct (6) supplying a cooling fluid, the hollow ring (5) extending into the annular chamber so as to surround the inner nozzle (12), and the wall of the ring (5) being formed with a number of orifices (7) distributed all along the ring so as to direct jets of cooling fluid on to the fixed plate (12) of the ladle cooling device around the casting hole in the plate (22).

Abstract: A spout for a recovery boiler such as those used in the papermaking industry. As in prior art spouts of this type, the spout is provided with an internal cavity to thereby permit water cooling of the spout. By this invention, a duct is provided for the internal cavity, the duct applying a portion of the coolant liquid to specific areas of the spout which in the past have failed. Further, the radius of curvature of the lowermost portion of the spout is increased by a factor of two. The useful life of the spout of this invention is in excess of twenty five weeks, as compared to a prior art spout whose useful life is about two weeks.

Abstract: An annular cooling chamber extends around the periphery of a ladle nozzle over at least some of the nozzle length, a hollow ring being so disposed in the annular chamber as to extend coaxially of the runner (casting channel), the ring wall being pierced with orifices along ring length. The ring interior communicates with a cooling fluid supply line, the wall of the annular chamber being formed with an aperture for removal of the cooling fluid distributed by the distributor ring in the annular chamber.

Abstract: The invention provides an arrangement for producing solid metal with fine solidification structure from liquid metal including the steps of transferring liquid metal with a minimum flow through a hollow carrier; the minimum bulk velocity of the metal through the carrier being 50 cm/sec.

Abstract: A molten metal teeming valve of the sliding gate type is equipped with means for the injection of gas for various purposes including refractory preheating, lancing, or cooling, etc. The gas injecting apparatus is arranged within the valve organization in a manner that will prevent impingement of the injected gas streams on the refractory valve elements thereby avoiding damage to such elements.

Abstract: Cold-hearth melt-spinning apparatus for adapted improved continuous casting of refractory and reactive alloys possesses (1) a cold crucible having a selectively grooved surface operative to reduce both melt "freezing" at the melt/crucible interface and input heating power requirements, and (2) a replaceable nozzle of a refractory material that is friction-fit in an aperture provided therefor in the crucible. The confronting nozzle/crucible walls define a thermally impeding interface which maintains the nozzle at a temperature sufficient to substantially eliminate melt "freezing" in and across the nozzle orifice. The melt is ejected as a molten jet from the crucible by pressure, rapidly quenched on a suitably configured spinning disk into either filaments or flakes, and passed to an environmentally protected processing compartment. Arc heating of the melt is provided by a water-cooled and selectively movable electrode.

Abstract: Very finely granular metal powders are produced by atomizing a liquid jet of metal by means of a gas jet which, in addition to a continuous band of sound frequencies, contains at least one discrete sound frequency which is at least 5 decibel above the average intensity of this band, and which is generated in a rotationally symmetrical device by means of a nozzle (4) which has the shape of a hollow cone and by means of an annular resonance space (7) with an annular edge (6) and is projected concentrically against the liquid jet of metal at a total opening angle of an average 35.degree. to 55.degree.. The atomization zone of the gas jet should preferably contain at least three discrete sound frequencies which are each at least 10 decibel above the sound intensity of the continuous band.

Abstract: An arrangement for controlling the pouring of a melt out of a crucible with a hole in the bottom which hole is blocked while the material is being melted with a closure plate that melts through locally as the result of heat transferred from the melt. To precisely establish the time at which the closure plate melts through, the plate is cooled from below while the starting material is being melted. Cooling is at least decreased and preferably terminated when it is time to pour out the melt. The plate can be cooled by a flow of a gas coolant directed against it or by contact with a cooling element that is raised into position against it from below.

Abstract: A taphole for a melting furnace includes a cylindrically shaped copper shell having a central opening through which molten material from a furnace passes and includes a reduced inner diameter portion defining an orifice. A plurality of narrow holes are formed in the shell wall adjacent the orifice but isolated therefrom and are interconnected to form a plurality of highly restrictive flow passages. Coaxially arranged about the copper shell is a coolant guide having a surface which is closely spaced from the copper thereby defining another highly restrictive flow passage which is also in communication with the plurality of passages around the orifice. A liquid coolant is supplied to the passages where the velocity of the same is made to accelerate to an ultrahigh velocity of at least 10 feet per second across nonworking surfaces of the copper shell forming parts of said passages to thereby sweep away steam generated upon the surfaces.

Abstract: A trough for delivering molten material flowing from a furnace includes an elongated copper member along which the material flows. A coolant guide is located beneath the copper member and is closely spaced therefrom so as to define a highly restrictive narrow coolant flow passage. A liquid coolant is supplied to the passage where the velocity of the same is made to accelerate to an ultrahigh velocity of at least 10 feet per second across the undersurface of the copper member to thereby sweep away steam generated upon the surface.