Abstract: Systems and methods recycle liquid(s) by introducing at least a portion of a first liquid from a first centrifuge into a tank. At least a portion of a second liquid is introduced from a second centrifuge into the tank. The first liquid and the second liquid are mixed together in the tank to produce a mixed liquid. At least a portion of the mixed liquid is introduced from the tank into the second centrifuge. Particles from the mixed liquid are separated using the second centrifuge, thereby producing the at least a portion of the second liquid that is introduced from the second centrifuge into the tank.

Abstract: A method and system for generating an ionized fluid, injecting the ionized fluid into fissures in a subterranean formation, pressurizing the ionized fluid, whereby the crystalline structure of a portion of the shale deposits located at the fissures are changed into suspended particles, whereby the depressurization of the ionized fluid forces the suspended particles out of the fissures, increasing the flow of hydrocarbons from those fissures.

Abstract: A drilling and grouting device comprises a drill string including a hollow elongate outer rod having a central axis and a hollow elongate inner rod located coaxially within said outer rod, wherein a first outer flow path is defined between said inner and outer rod, and a first central flow path is defined inside said inner rod, a drill bit aligned with said inner rod along said central axis and including a second central flow path, and a crossover part interposed between said inner rod and said drill bit along said central axis, which is configured to connect the first central flow path with a second outer flow path surrounding the drill bit to form a main path and to connect said first outer flow path with said second central flow path to form a secondary path. Also disclosed are systems and methods that include and use the device.

Abstract: A water pump control system is provided for vacuum excavation equipment. The water pump control system includes a control circuit for controlling a hydraulic actuation circuit configured to control a water pump circuit such that a water pressure produced by the water pump circuit does not exceed a desired water pressure. The hydraulic actuation circuit can include a proportional hydraulic valve, and the control circuit controls a water pump speed by monitoring a water pressure and adjusting an electric current flowing into the proportional valve to meet the desired water pressure. The control circuit can include a pressure transducer mounted to the water pump circuit to monitor the water pressure in real-time.

Abstract: The present invention relates to a vector sensor for measuring particle movement in a medium. The vector sensor comprises a magnetic body that is held at a certain distance from a magnetometer in such a way that the magnetic body can move in time with a passing particle movement, wherein the magnetometer is arranged to detect the oscillations in the magnetic field that the movements in the medium produce.

Abstract: A process for separating synthetic turf product comprising includes the consecutive steps of: (a) downsizing the synthetic turf product into a downsized turf material; (b) separating the downsized turf material by sieving into at least a first fraction substantially comprising a mixture of backing material and additional components and a second fraction substantially comprising grass fiber components; (c) separating the first fraction by specific gravity to provide a low density fraction and a high density fraction; (d) separating the second fraction by specific gravity and size by providing an airflow directed upwards in a separator configured to cause a swirling motion whereby a lighter fraction is entrained upwards in the air flow and a heavy fraction is allowed to fall downwards; and (e) collecting the low density fraction and the light fraction.

Abstract: A wellbore strengthening material collection system including a vibratory separator having a top deck, a middle deck, and a bottom deck, and also including a collection trough coupled to at least one of the decks and configured to receive wellbore strengthening materials from the at least one of the decks. Additionally, a collection trough including a body having an inlet and an outlet, an angled surface disposed within the body and at least on extension surface extending form the body and configured to secure the collection trough to a vibratory separator.

Abstract: Methods and processes for recycling base oils from spent invert emulsion drilling fluids may include frictionally heating a spent drilling fluid that comprises an invert emulsion and solids, wherein the solids are at about 50% or less by volume of the spent drilling fluid; and simultaneously evaporating oil and water from the invert emulsion at a temperature lower than an atmospheric boiling point for the oil.

Abstract: The present disclosure provides methods and techniques for manufacturing proppant or lost circulation material from drilling cuttings. In an example embodiment, a method for manufacturing proppant or lost circulation material from drilling cuttings includes obtaining solid drilling cuttings from drilling fluid, removing any remaining hydrocarbon from the solid drilling cuttings, and rending the solid drilling cuttings into a powder form. The method further includes using the powdered drilling cuttings as raw material in a proppant or lost circulation material manufacturing process. In an example embodiment, the proppant or lost circulation material manufacturing process can be sintering or flame spheroidization.

Abstract: A method and system for generating an ionized fluid, injecting the ionized fluid into fissures in a subterranean formation, pressurizing the ionized fluid, whereby the crystalline structure of a portion of the shale deposits located at the fissures are changed into suspended particles, whereby the depressurization of the ionized fluid forces the suspended particles out of the fissures, increasing the flow of hydrocarbons from those fissures.

Abstract: A system and method for the treatment of wastewater. In one aspect, the invention can be a method of treating wastewater comprising: a) introducing wastewater having a first turbidity level into a wastewater treatment system; b) injecting an aqueous polymer mixture into the wastewater to flocculate suspended solids within the wastewater; c) removing the flocculated suspended solids from the wastewater to form a treated water having a second turbidity, the second turbidity being lower than the first turbidity; and wherein the aqueous polymer mixture of step b) is formed by introducing a raw polymer into a re-circulated portion of the treated water.

Abstract: Methods and processes for recycling base oils from spent invert emulsion drilling fluids may include frictionally heating a spent drilling fluid that comprises an invert emulsion and solids, wherein the solids are at about 50% or less by volume of the spent drilling fluid; and simultaneously evaporating oil and water from the invert emulsion at a temperature lower than an atmospheric boiling point for the oil.

Abstract: A method of processing a return oil-based drilling fluid includes centrifuging a primarily fluids phase at a first speed and separating the primarily fluids phase into a first effluent and a first residual, centrifuging the first effluent at a second speed and separating the first effluent into a second effluent and a second residual, and centrifuging the second effluent at a third speed and separating the second effluent into a third effluent and a third residual. A surfactant, a polymer, combinations of surfactant(s) and polymer(s) and/or a wash water may be added to one or more of the return oil-based drilling fluid, the primarily fluids phase, the primarily solids phase, the first effluent, the second effluent, and the third effluent.

Abstract: A drilling system including a riser, a pressure vessel, a source of pressurized gas, and a main flow line which extends from the riser to the pressure vessel, the pressure vessel having a liquid inlet port connected to the main flow line, a gas inlet port connected to the source of pressurized gas, a liquid outlet port located in a lowermost portion of the pressure vessel, and a gas outlet port located in an uppermost portion of the pressure vessel.

Abstract: A method of extracting recovering oil from vegetable material in which oil bearing material is heated and subjected to sonication at least one frequency above 400 kHz, removing a first yield of oil by decanting and subjecting the retained material to centrifugal separation to separate out a second yield of oil. Preferably the raw vegetable material is passed through a screw press and the obtained material is heated and subjected to the ultrasonic treatment and then allowed to settle for a predetermined period before decanting the oil layer. Preferably two frequencies above 400 kHz are used, one below 1 MHz and the second from 1 MHz. There are many potential transducers arrangements possible for producing standing waves.

Abstract: A slug mitigation system for subsea pipelines includes a riser located between a low level and an upper (above sea-) level of a pipeline, where an inline separator, e.g. an “I-SEP”, is located upstream of a first stage separator. A throttling valve or fixed restriction is located downstream or upstream in series with the inline separator. Further aspects may also include a surface jet pump upstream of the in-line separator and/or a cyclonic separator downstream of the in-line separator.

Abstract: A method of extracting recovering oil from vegetable material in which oil bearing material is heated and subjected to sonication at least one frequency above 400 kHz, removing a first yield of oil by decanting and subjecting the retained material to centrifugal separation to separate out a second yield of oil. Preferably the raw vegetable material is passed through a screw press and the obtained material is heated and subjected to the ultrasonic treatment and then allowed to settle for a predetermined period before decanting the oil layer. Preferably two frequencies above 400 kHz are used, one below 1 MHz and the second from 1 MHz. There are many potential transducers arrangements possible for producing standing waves.

Abstract: A method for controlling a downhole pressure during drilling comprises continually sensing in real-time at least one real-time fluid property of an input fluid to a well and of a return fluid from the well. A wellhead setpoint pressure is calculated in real-time that results in a predetermined downhole pressure at a predetermined location in the well, where the calculation based, at least in part, on the at least one continually sensed real-time fluid property. The flow of the return fluid is controllably regulated to maintain the calculated wellhead setpoint pressure.

Abstract: A method and apparatus for remediating porous contaminated material. In the method, fuel material is combined with the contaminated material and a smoldering combustion process is initiated in the contaminated material to remediate the contaminated material. Control systems are provided to control the smoldering combustion process. The contaminated material may include oily waste, asbestos fibers, and/or at least one of a chlorinated solvent, a polychlorinated biphenyl (PCB), a dioxin, a furan and a polynuclear aromatic hydrocarbon (PAH).

Abstract: A system and method for separating two or more materials, such as a solid from a liquid, or a solid from a slurry, are provided. An exemplary system and method for separating drill cuttings from drilling fluids are provided, as well as a system and method of processing such separated drill cuttings. In another implementation, a system and method is provided for separating gold (or another mineral, element, or solid) from a slurry or liquid that includes mining cuttings.

Abstract: A system for detecting oil contaminated product and foreign matter within a product stream is provided. The system includes a first conveying means for delivering a product stream; a first detection apparatus for detecting oil contaminated product, the first detection apparatus positioned proximate the product stream, the first detection apparatus including a high intensity infrared light source directed at the product stream; and a high speed NIR spectrometer sensor tuned to detect a reflected signal from a taggant disposed in the oil of the oil contaminated product; a second detection apparatus for detecting foreign matter within a product stream, the second detection apparatus positioned proximate the product stream, the second detection apparatus including a light source for illuminating the product stream and a detector for detecting light reflected from the product stream; and a controller for determining whether the product stream contains oil contaminated product or foreign matter.

Abstract: A diverter system having stabbing dogs is provided. In one embodiment, such a system includes a diverter, a housing, and a plurality of stabbing dogs coupled to the housing. The stabbing dogs are positioned to enable locking elements of the stabbing dogs to be extended into recesses in the diverter to secure the diverter within the housing. At least one of the recesses in the diverter is connected to a fluid conduit within the diverter, and at least one stabbing dog includes a fluid passage that enables fluid to be routed into the fluid conduit within the diverter through the at least one stabbing dog. Additional systems, devices, and methods are also disclosed.

Abstract: A drill cuttings conveyance system includes a collection tank that includes a screw conveyor and a chamber operable to accommodate drill cuttings, the screw conveyer extending along a longitudinal axis of the collection tank from a first end of the chamber to a second end of the chamber; a port disposed at the second end of the chamber of the collection tank, the port including a channel operable to direct the drill cuttings from the chamber of the collection tank; a pump including an inlet connected to the port and operable to receive drill cuttings from the port, an outlet, and a pumping mechanism operable to direct the drill cuttings through the outlet of the pump; and a drag chain conveyor in communication with the chamber of the collection tank via an auxiliary opening, the drag chain conveyor being operable to remove drill cuttings from the collection tank.

Abstract: Embodiments of the present invention generally relate to methods and apparatus for centrifugal separation. In one embodiment, a separator includes an outer tubular having ends sealed from the environment and an inner tubular. The inner tubular is disposed within the outer tubular, has ends in fluid communication with a bore of the outer tubular, and is attached to the outer tubular. The separator further includes an inlet. The inlet is disposed through a wall of the outer tubular, in fluid communication with a bore of the inner tubular, and tangentially attached to the inner tubular so that fluid flow from the inlet to the inner tubular is centrifugally accelerated. The separator further includes a gas outlet in fluid communication with the outer tubular bore; and a liquid outlet in fluid communication with the outer tubular bore.

Abstract: A low headroom confined space drilling system is disclosed, comprising a low headroom drilling apparatus, a drilling fluid supply system, a drilling fluid collection system, and a drilling fluid recycling apparatus for supplying a recycled drilling fluid to the drilling apparatus. A method of installing a geoexchange borehole in an interior space of a building is also disclosed, comprising installing a borehole access chamber in a floor slab of a building, positioning a low headroom floor mounted rotary drilling apparatus over the borehole access chamber, providing a pressurized drilling fluid to the drill rod string and powering a rotary downhole drilling device attached to the drill rod string to advance the borehole to a desired depth, recovering a drilling fluid and drill cuttings from the borehole, removing drill cuttings from the recovered drilling fluid using the drilling fluid recycling apparatus and returning a recycled drilling fluid to the drilling apparatus.

Abstract: Methods and related systems are configured to treat a drilling fluid to cause water droplets to coalesce. One or more phases are thereafter separated from the treated drilling fluid. The oil and/or solids separated from the treated drilling fluid may be added to a base fluid.

Abstract: Embodiments disclosed herein relate to a fluid distribution apparatus. The fluid distribution apparatus has a housing including an inlet configured to receive a drilling material, a first outlet configured to direct a first portion of the drilling material onto a first separatory surface, and a second outlet configured to direct a second portion of the drilling material onto a second separatory surface. The fluid distribution apparatus further includes a screen disposed within the housing and configured to separate solids from the second portion of the drilling material directed through the second outlet onto the second separatory surface.

Abstract: Embodiments relate generally to drill cuttings conveyance systems comprising a collection tank, a port, and a pump. The collection tank comprises a chamber operable to accommodate drill cuttings and a screw conveyor. The screw conveyor extends along a longitudinal axis of the collection tank from a first end of the chamber to a second end of the chamber. The port comprises a channel operable to direct drill cuttings from the chamber of the collection tank to the pump. The pump comprises an inlet operable to receive drill cuttings from the port, an outlet, and a pumping mechanism operable to direct drill cuttings through the outlet of the pump.

Abstract: One embodiment of the invention disclosed is an apparatus for separating a solid material from a mixture containing oil, water, clay, sand, soil and drill cuttings. The apparatus comprise a series of processing cells and wash tanks. Hydrocyclonic devices are also used to further purify the solid mixture for disposal.

Abstract: The object of the present invention is a composition comprising amine compound and carboxylic acid compounds, wherein at least the amine compounds are alkoxylated, use thereof as a drilling fluid, and a method for using the drilling fluid

Abstract: This application relates to an apparatus and method for cleaning drill cuttings recovered from a wellbore. Specifically, the apparatus includes an effective system for handling and washing drill cuttings at a well site to remove hydrocarbon contaminants. The system successively washes hydrocarbon contaminated drill cuttings in organic solvent and water to remove and recover the hydrocarbon contaminates, and produce cleaned drill cuttings that may enable disposal of clean drill cuttings without further treatment.

Abstract: A vibratory separator including a separator deck including a hinge point, and a positive displacement mechanism coupled to the separator deck and configured to displace the separator deck to an angle of inclination is disclosed. A method of separating solids form a slurry, the method including pumping a slurry onto a separator deck, vibrating the separator deck, and displacing an end of the separator deck in an upwards or downwards direction with a positive displacement mechanism to a selected angle of inclination is also disclosed.

Abstract: A method of reclaiming a formate brine may include increasing the pH of a spent formate brine fluid comprising water-soluble polymers; treating the fluid with an oxidizing agent; and removing at least a portion of suspended solids from the fluid. Further, a method of reclaiming a formate brine may include lowering the pH of the spent formate brine fluid comprising water-soluble polymers; increasing the pH of the spent formate brine fluid to initiate precipitation of materials solubilized in the fluid; treating the fluid with an oxidizing agent to break down remaining water-soluble polymer; and recovering at least a portion of the formate brine.

Abstract: The present invention is generally directed to a closed loop apparatus, system, process or method adapted for processing drilling mud used in a down hole well drilling process such that any undesirable particulate such as cuttings will be substantially, if not completely separated from the dirty mud while at the same time allowing the recycled drilling mud to be continuously circulated with the drilling mud. In one embodiment, the present invention includes the following components, all in fluid or mud flow communication with one another and with an adjacent drilling rig: at least one clean mud mixing tank, at least one pump system, at least one dirty mud shakers, at least one optional conveyor belt system, at least one recycled mud reclamation tank and one or more filtering centrifugal pumps or centrifuge systems.

Abstract: A closed loop drilling fluids circulation system includes a first drilling fluid circulation system disposed at a first subterranean drill site. The first drilling fluid circulation system includes a supply tank for holding clean drilling fluid and a solids control device configured to separate solids from used drilling fluid. In addition, the system includes a central processing facility disposed at a location remote from the first drill site and configured to receive used drilling fluid from the solids control device and supply clean drilling fluid to the supply tank.

Abstract: A method of treating a wastewater is provided and can be used, for example, to treat a gas well hydrofracture wastewater. The method can involve precipitating barium as barium sulfate, precipitating calcium and strontium as calcium carbonate and strontium carbonate, precipitating magnesium hydroxide, and filtering out the metal compounds to form a recycle water. The recycle water produced from the method is also provided, as is a method for using the recycle water as a gas well hydrofracture water. In some embodiments, discharge water from a coal mine, and/or water from an abandoned coal mine, is used as a source of sulfate ions to precipitate barium as barium sulfate.

Abstract: There is provided a device and method for control of return flow from a borehole (18) where drill fluid is supplied from a surface rig (16) via a multi section drill string (4) to a bottom hole assembly (18), the drill pipe sections (6) having tool joints (8) that include an enlarged outer diameter portion (9), and where an annulus (12) is formed between a pipe (2) and the drill string (4), and where the annulus (12) is in fluid communication with or forms part of a return path (40) for the drill fluid, and where a choke (1) is positioned in the annulus (12), and where the length (L) of the choke (1) exceeds the distance (M) between the enlarged outer diameter portion (9) of two adjacent tool joints (8).

Abstract: This application relates to an apparatus and method for cleaning drill cuttings recovered from a wellbore. Specifically, the apparatus includes an effective system for handling and washing drill cuttings at a well site to remove hydrocarbon contaminants. The system successively washes hydrocarbon contaminated drill cuttings in organic solvent and water to remove and recover the hydrocarbon contaminates, and produce cleaned drill cuttings that may enable disposal of clean drill cuttings without further treatment.

Abstract: A drilling rig with continuous microwavable particulate treatment system for treating fluid from a wellbore on an offshore platform. The system uses a materials handling controller, a vibrating sieve device or filtering device to separate particulate from drilling fluid, a cuttings discharge collection device for continuously moving the slurry to a cuttings processing station, a treatment system controller controlling the continuous cuttings processing station that uses a microwave generator creating microwaves that heat the slurry and a plurality of non-deforming microwave heatable polishing and grinding media in a vibrating trough. The system continuously creates water vapor with oil droplets and cleaned cuttings, and a vapor recovery system is used for removing the oil droplets from the water vapor having a vapor recovery system controller in communication with the material handling controller and treatment system controller.

Abstract: The present invention relates to methods of drilling a wellbore wherein a drill-in fluid is foamed at the drill tool. A method in accordance with the present invention comprises providing a drill-in fluid comprising an aqueous fluid, a foaming agent, a foam stabilizer, a gas generating chemical and an encapsulated activator; introducing the drill-in fluid downhole into a drill string connected to a drill tool; and allowing the drill-in fluid to exit the drill tool where, upon exiting the drill tool, the encapsulated activator is de-capsulated sufficiently to react with the gas generating chemical such that a gas is generated within the drill-in fluid and thus foams the drill-in fluid.

Abstract: A method for optimizing drilling fluids by creating a proper particle size analysis and distribution curve of particle sizing within drilling fluid. The particle size distribution curve is maintained with a maximum particle sizing of 6 microns so as to not allow for coarser drilled solids to degrade beyond the point of mechanical separation to prevent a build-up of low gravity solids that can no longer be removed from the drilling fluid during the drilling operation due to their size. An optimal drilling system requires that drilling fluids be modified through the following process to attain the appropriate particle sizing distribution to: make the most efficient use of the drilling operation, reduce the amount to drilling fluids utilized, and reduce formation damage. The method generates corrective actions to modify the drilling fluids or adjust solids control equipment parameters, to obtain a unique particle size distribution throughout the drilling process.

Abstract: A continuous microwave particulate treatment system for treating fluid from a wellbore. The system uses a material handling controller, a vibrating sieve device or filtering device to separate particulate from drilling fluid, a cuttings discharge collection device for continuously moving the slurry to a cuttings processing station, a treatment system controller controlling the continuous cuttings processing station that uses a microwave generator creating microwaves that heat the slurry and a plurality of non-deforming microwave heatable polishing and grinding media in a vibrating trough. The system continuously creates water vapor with oil droplets and cleaned cuttings, and a vapor recovery system is used for removing the oil droplets from the water vapor having a vapor recovery system controller in communication with the material handling and treatment system controllers.

Abstract: A method for separating hydrocarbon content from a hydrocarbon contaminated matrix. The method includes controlling water content of a feed material having the hydrocarbon contaminated matrix; continuously conveying the feed material into a treatment cavity; exposing the feed material in a treatment area of the treatment cavity to microwave radiation arranged to cause rapid heating of at least a portion of the water content to form steam, wherein the rapid steam formation results in thermal desorption of at least a portion of the hydrocarbon content from the matrix; and continuously removing the treated matrix from the treatment cavity.

Abstract: A method of servicing a wellbore in a subterranean formation comprising placing a foamed wellbore servicing fluid into a wellbore; flowing the foamed wellbore servicing fluid back to the wellbore surface; and contacting the foamed wellbore servicing fluid with an immobilized defoaming agent structure comprising an inert substrate and a defoamer. A system comprising a foamed wellbore servicing fluid in contact with a de-foaming structure, wherein the de-foaming structure comprises a defoamer covalently bonded to an inert substrate.

Abstract: The present invention relates to an emulsion, consisting of an oil phase and an aqueous phase and comprising as emulsion components (?1) 15 to 40% by weight of at least one water-immiscible organic solvent as solvent of the oil phase, (?2) 15 to 40% by weight of water as solvent of the aqueous phase, (?3) 10 to 40% by weight of at least one surfactant, (?4) 10 to 40% by weight of an alkoxylated fatty alcohol and (?5) 0 to 25% by weight of at least one other additive, wherein the quantities by weight of the components (?1) to (?5) are each relative to the total weight of the emulsion, and together add up to 100% by weight. The invention further relates to a method for producing an emulsion, to the emulsion which can be obtained from said method, to the use of an emulsion, to a method for cleaning the surfaces of well holes, drilling devices or drillings, to a method for producing a well bore, and to a method for producing an oil or a gas.

Abstract: Aspects of the present disclosure also involved a method of processing waste, such as drill cuttings, involving the operations of receiving a waste material comprising a liquid material and a solid material, the waste material received directly from a source wherein the waste material is warm. The source may be a drilling operation and the waste material may be drill cuttings from the drilling operation. The method further involving pumping the warm waste material to a separation mechanism, such as a dryer, that separates a portion of the solid material (e.g., cuttings) from a portion of the liquid material (e.g., drilling fluid). The method may further involve mixing the separated solid material with a bioremediation agent.

Abstract: A system for conditioning drilling fluid includes a conditioning device having a first conduit configured to receive the drilling fluid, a flow restriction disposed adjacent the first conduit, the flow restriction comprising a fluid inlet and a fluid outlet, an impact plate disposed downstream of the flow restriction, a first chamber disposed between the flow restriction and the impact plate, and a second chamber disposed downstream of the impact plate, wherein the first chamber is fluidly connected to the second chamber. A method for conditioning drilling fluid using a conditioning device, includes pumping a drilling fluid through a flow restriction, accelerating the drilling fluid into a mixing chamber, subjecting the drilling fluid to elongational shearing, decelerating the drilling fluid against an impact plate, subjecting the drilling fluid to impact shearing, and emptying drilling fluid from the mixing chamber.

Abstract: A tank cleaning system for use at a drilling location, including a first cuttings storage vessel comprising an inlet and an outlet, at least one tank cleaning machine configured to clean a tank, a disposal vessel, and a module including a pump configured to facilitate the transfer of fluids from a clean water vessel to the at least one tank cleaning machine, and a fluid connection configured to facilitate the transfer of fluids from the outlet of the first cuttings storage vessel to the disposal vessel.

Abstract: In one aspect, embodiments disclosed herein relate to modular drilling system, the system comprising a first module comprising a first work surface; and a second module comprising a second work surface; wherein the first module is disposed above the second module. In another aspect, embodiments disclosed herein relate to a modular drilling system, the system comprising a first module; and a second module; wherein at least one of the first and second modules comprises oilfield process equipment disposed on the module around a center point.

Abstract: The present invention is generally directed to a closed loop apparatus, system, process or method adapted for processing drilling mud used in a down hole well drilling process such that any undesirable particulate such as cuttings will be substantially, if not completely separated from the dirty mud while at the same time allowing the recycled drilling mud to be continuously circulated with the drilling mud. In one embodiment, the present invention includes the following components, all in fluid or mud flow communication with one another and with an adjacent drilling rig: at least one clean mud mixing tank, at least one pump system, at least one dirty mud shakers, at least one optional conveyor belt system, at least one recycled mud reclamation tank and one or more filtering centrifugal pumps or centrifuge systems.