Abstract: A fire apparatus includes a chassis, axles coupled to the chassis, a turntable rotatably coupled to the chassis, and an aerial ladder assembly pivotably coupled the turntable. The aerial ladder assembly includes a first ladder section extending longitudinally, a second ladder section extending longitudinally, and a support slidably coupling the second ladder section to the first ladder section such that the first ladder section supports the second ladder section. The support facilitates longitudinal movement of the second ladder section relative to the first ladder section between an extended position and a retracted position. The support is pivotably coupled to the first ladder section.

Abstract: The present invention pertains to a stepladder. The stepladder includes a ladder top having a plane having a front side and a rear side and a left side and a right side and a front side flange and a rear side flange and a left side flange and a right side flange. The stepladder includes a conduit holder slot for holding tubing, pipe and conduit. The conduit holder slot extends along the entire length of the top and in the right side and the left side. The conduit holder slot has a cross-section in the ladder top which is non-symmetrical. The stepladder includes a front section. The stepladder includes a rear section. A method for cutting a tube.

Abstract: The invention relates to a ground processing tool and a method for creating a borehole in the ground, wherein ground material is removed by the ground processing tool and blended with a fluid in the created borehole to form a suspension, which is suctioned away via at least one opening in the at least one mixing blade and via the conducting channel in the central shaft.

Abstract: An apparatus for use in a wellbore is disclosed that in one non-limiting embodiment includes a rotatable member, a thrust bearing coupled to the rotatable member, wherein the thrust bearing includes a bearing stack that further includes a unitary inner race member that includes a number of axially spaced inner races around an outer surface of the unitary inner race member. A set of bearing elements is placed in each inner race, and a separate outer race secures each set of bearing elements in each inner race.

Abstract: A well tool can include inner and outer seals interposed between components of the well tool, and a circumferential spacer which prevents contact between the inner seal and one of the components which displaces relative to the inner seal. A method of sealing between components of a well tool can include sealingly engaging an outer seal between the components, and disposing an inner seal between the components, including spacing the inner seal away from one of the components, whereby the inner seal sealingly contacts one of the components only after the well tool is disposed in a well. A drill bit can include inner and outer seals interposed between components of the drill bit, and a circumferential spacer which prevents contact between the inner seal and one of the components, the circumferential spacer being positioned upstream of the outer seal relative to a lubricant supply of the drill bit.

Abstract: An earth-boring tool includes a body and a rotating member disposed over a protrusion from the body and configured to rotate relative to the body. A bearing assembly may be disposed within a cavity of the rotating member. The bearing assembly may include an inner race coupled with the body and an outer race coupled with the rotating member. A bearing retainer may be affixed within the cavity of the rotating member and may retain the bearing assembly within the cavity of the rotating member. The earth-boring tool further includes a seal assembly including a sealing element rotationally coupled with the rotating member, the sealing element comprising a first sealing surface. A second sealing surface may be disposed on the inner race, and an energizing element urges the first sealing surface into sealing engagement with the second sealing surface.

Abstract: A cutting element assembly may include a support structure and a pin having a cylindrical exterior bearing surface. Retention elements may couple opposing ends of the pin to the support structure. The cutting element assembly also includes a rotatable cutting element including a table of polycrystalline hard material having an end cutting surface and a supporting substrate. The rotatable cutting element may have an interior sidewall defining a longitudinally extending through hole. The pin may be positioned within the through hole of the rotatable cutting element and may be supported on the opposing ends thereof by the support structure. Methods include drilling a subterranean formation including engaging a formation with one or more of the rotatable cutting elements.

Abstract: An earth-boring tool includes a body having a longitudinal axis. The earth-boring tool also includes blades extending longitudinally and generally radially from the body. The earth-boring tool may also include one or more polished superabrasive cutting elements located on at least one blade in at least one region of a face of the earth-boring tool, and one or more non-polished superabrasive cutting elements located on the at least one blade in at least another region of the face of the earth-boring tool. Methods include drilling a subterranean formation including engaging a formation with one or more polished superabrasive cutting elements and one or more non-polished superabrasive cutting elements of the earth-boring tool secured at selected locations of one or more regions of blades extending from a body of the earth-boring tool.

Abstract: A cutting element includes a table coupled to a substrate at an interface. The table includes a working surface opposite the interface and defined by a perimeter, a table thickness measured between the interface and the working surface, and a torque transmittable depression formed in the working surface of the table a distance away from the perimeter. The torque transmittable depression extends a depth into the table and has a cross-sectional profile with a torque transmittable shape. The depth of the depression may be greater than the thickness of the table, or an optional sensor may be placed in the depression.

Abstract: Tubing encapsulated cable consists of one or more electrical conductors and possibly one or more fiber optic cables sheathed in a corrosion resistant metallic alloy. However, pumping during the installation of tubing encapsulated cable is required to overcome the capstan effect of the tubing encapsulate cable inside the coil tubing as the tubing encapsulated cable travels through the coiled up wraps of coil tubing. In an embodiment of the invention the tubing encapsulated cable consists of one or more electrical conductors and possibly one or more fiber optic cables sheathed in a fiber reinforced composite sheath. Because there is little drag between the fiber encapsulated cable and the coil tubing, conventional pumping operations used to install braided wireline into coil tubing may not be required when installing fiber encapsulated cable into coil tubing.

Abstract: A drilling machine having: a string of telescopic rods provided with an excavation tool; a winch having a drum associated with a motor; a flexible pulling element connected on the one hand to the drum and on the other hand to the string of telescopic rods; a manual control element of the winch that can assume a first position, a second position and a third position; a control system configured for controlling the motor, in a first operating mode, so as to unwind the flexible pulling element from the drum when the manual control element is in the first position, wind the flexible pulling element on the drum in order to raise the string of telescopic rods when the manual control element is in the second position, stop the drum when the manual control element is in the third position; wherein it comprises a first manual selector adapted to select a second operating mode, and in that the control system is configured for controlling the motor, in the second operating mode, so as to wind the flexible pulling elemen

Abstract: A device for suspending a tubular from a floating vessel includes a first element which carries the tubular, a second element supported by the floating vessel, and a compression element which forms a connection between the first element and the second element. The compression element is pre-tensioned in an end stroke position so that, when the compression element is subjected to a force from the tubular which is below a pre-defined threshold force, the connection formed by the compression element between the first and second element is a rigid connection, and, when the compression element is subject to a force from the tubular which is higher than the pre-defined threshold force, the connection formed by the compression element between the first and second element is a compressible connection.

Abstract: Spring discs are rotationally locked to the mandrel are between pairs of actuation rings that feature a circumferential protrusion. On application of axial force release of a stored force from flexing, the protrusion engages a sloping portion of the spring disc and moves the sloping portion toward a more vertical orientation. Alternatively, a release of a stored force from flexing accomplishes the same result. Slots in the spring disc allow irregular growth to conform to surface irregularities of a surrounding surface. The discs can serve as anchors, centralizers or supports for a sealing element in a packer. Ends of fingers feature stiffeners to enhance strength. The discs can be stacked apart or together and oriented in the same or opposed directions. The can deliver an axial force when stacked and pushed toward flat and released.

Abstract: There is provided a downhole tool comprising a locator. The locator includes a wellbore coupler for becoming releasably retained relative to a locate profile; and a wellbore coupler release opposer configured for opposing release of the wellbore coupler from the retention relative to the locate profile. While the opposing of the release of the wellbore coupler from the retention relative to the locate profile is being effected by the wellbore coupler release opposer, relative displacement between the wellbore coupler release opposer and the wellbore coupler is effectible, with effect that the opposing is defeated. The locator also includes a displacement impeder for impeding the relative displacement between the wellbore coupler release opposer and the wellbore coupler.

Abstract: A method and apparatus for cutting and pulling a casing string from a well. A downhole casing pulling tool includes a tubular housing having a bore therethrough, a packer assembly configured to isolate an annulus between a casing and the tool, a slip assembly configured to engage the casing, and a piston assembly disposed in the bore of the tubular housing. The piston assembly is configured to operate an actuator, wherein the actuator is configured to operate at least one of the packer assembly and the slip assembly and modify a fluid pressure in the bore of the tubular housing.

Abstract: A disintegrable polymer composite comprises: a polymer component comprising one or more of the following: a cured cyanate ester; a crosslinked unsaturated polyester; or a crosslinked vinyl ester resin; and dissolvable glass comprising about 55 to about 80 wt. % of SiO2, 0 to about 35 wt. % of Na2O, 0 to about 35 wt. % of K2O, 0 to about 20 wt. % of CaO, 0 to about 10 wt. % of MgO, provided that the sum of the weights of Na2O and K2O is about 20 wt. % to about 40 wt. %, wherein each weight percent is based on the total weight of the dissolvable glass.

Abstract: Embodiments of the present disclosure include a test dart for wellbore pressure isolation. The test dart includes a body extending from a first end to a second end, the body having a bore extending therethrough, a diameter of the bore being greater at a first end than the second end. The test dart also includes a groove formed proximate the first end and extending radially outward from the bore and into the body. Additionally, the test dart includes an anti-rotation pin positioned between the groove and the second end, the anti-rotation pin extending radially outward from the body. The test dart further includes a check valve positioned in the bore, the check valve enabling flow in a single direction and being moveable between an open position to enable the flow and a closed position to block the flow.

Abstract: An inflating container filled with formation plugging fluid is deployed at the target zone by a rigless apparatus. The inflating container can be in valved fluid communication with an explosive filled container, the explosive being ignited using a firing mechanism that is attached to the explosive filled container. The explosion expands gases in the explosive filled container which pass into the inflation container and displace the formation plugging fluid into the balloon sections and through the weakened portions of the central balloon to penetrate the walls of the target zone. The expanded central balloon is melted by the heat of the chemical reaction and a portion adheres to the formation wall thereby sealing the undesirable target zone; thereafter, the remaining balloon sections are deflated or ruptured to permit the apparatus to be withdrawn through the production tubing.

Abstract: A technique facilitates plugging of a wellbore during, for example, a fracturing operation. A frac plug is constructed with an unobstructed internal passage and comprises a seal member combined with a plurality of slips for engaging a surrounding wall, e.g. a surrounding wellbore wall. Additionally, the frac plug comprises a lower sub having raised edges arranged to catch a ball during a flow back stage without blocking flow along the unobstructed internal passage.

Abstract: Downhole assemblies and methods for isolating a wellbore. A downhole tool can include a body having a bore or flowpath formed therethrough, and one or more sealing members disposed therein. The one or more sealing members can include an annular base and a curved surface having an upper face and a lower face, wherein one or more first radii define the upper face, and one or more second radii define the lower face, and wherein, at any point on the curved surface, the first radius is greater than the second radius. The sealing members can be disposed within the bore of the tool using one or more annular sealing devices disposed about the one or more sealing members.

Abstract: A system for control using a hydraulic fluid includes a hydraulic control line for flowing the hydraulic fluid, a fluid line in fluid communication with the hydraulic control line, a flow controller configured to regulate a flow of the hydraulic fluid in the fluid line, and a piezoelectric device in fluid communication with the hydraulic control line and configured to actuate the flow controller upon receiving a selected flow of the hydraulic fluid.

Abstract: A method and apparatus for completing a well that includes a subsurface barrier valve utilizes an injection valve which includes a variable orifice insert. The injection valve includes a mechanism for sensing pressure cycles that are employed during various well completion operations including pressure testing. The mechanism includes an indexing sleeve which will disable pressure functionality. Once this occurs, pressure cycling to open the barrier valve can proceed. Once the barrier valve opens, flow alone controls the injection valve during normal operations.

Abstract: A downhole tool comprises a body having a fluid inlet and a fluid outlet and configured to accelerate fluid flowing along a fluid flow path from the inlet to the outlet. The fluid outlet is configured to provide a radially directed and substantially circumferentially continuous stream of fluid. The stream of fluid may be used to clean or cut downhole tubing, such as casing.

Abstract: A removable hand guard is provided for installation on drilling rig hand tongs and used to protect the hands of workers from being accidentally crushed when gripping the tong handle. The hand guard can include resilient body and tabs, which allow the guard to be positioned on the tong handle. The hand guard can be locked into place using locks and fasteners. The hand guard can include a slot, which can form a secondary handle to be used by a second worker to maneuver the tongs.

Abstract: A wellhead assembly for use with a well that includes a production tree, a production line for carrying produced fluid from the production tree, and a choke in the production line. The choke assembly includes a turbine member that rotates in response to fluid flowing through the production line. The kinetic energy of the rotating turbine is converted into electricity by a generator that is coupled with the turbine member. Selectively impeding turbine rotation with a brake system introduces a pressure drop in the production line fluid, and which regulates flow of the production line fluid. The turbine member can be disposed in a straight run of the production line, or adjacent a bend in the production line.

Abstract: Embodiments are directed to modeling physical material flow relationships between injector wells and producer wells in a reservoir and to quantifying a level of uncertainty in a connection-based model. In one scenario, a computer system calculates pressure distribution within the reservoir using sensor data. Next, the computer system applies the calculated pressure distribution as an input to a tracer algorithm for an injector well and for a producer well to identify tracer flow values for materials flowing from the injector well to the producer well. The computer system further combines the identified tracer flow values to generate well allocation factors representing relationships in material flow.

Abstract: This invention is a method of developing a sedimentary basin containing hydrocarbons, by using basin simulation. Starting with gridded representations representative of a basin for each time step of a simulation, for each time step and in each cell of the gridded representation the following steps are performed. First a determination of at least one amount of biogenic gas produced in the cell for the time step is preformed followed by determining at least one amount of biogenic gas dissolved in water present in the cell at the time step, and determining therefrom an amount of free biogenic gas in the cell at the time step; then, accounting for advective transport of the quantity of biogenic gas dissolved in the water of the cell at the time step.

Abstract: A method for completing a wellbore extending through a subterranean formation may include installing a sandface completion assembly in the wellbore; pumping a solids free fluid comprising chemical precursors into an annulus formed between the subterranean formation and the sandface completion assembly; triggering and/or controlling chemical reaction between the chemical precursors to form a plurality of solid particles in the annulus.

Abstract: A method of forming a screen assembly includes arranging a first end portion of each of a plurality of rib members into a rib alignment jig, positioning a sleeve about the rib alignment jig with an inner surface of the sleeve abutting the first end portion of each of the plurality of rib members, and resistance welding the sleeve to the first end portion of each of the plurality of rib members.

Abstract: A screen filter assembly and method for filtering solids within a pump barrel of a pump system. The screen filter assembly is incorporated into a full-length plunger, which contains a screen to filter solids from dirty production fluid. By filtering dirty production fluid, the screen filter assembly keeps the solids off of the plunger and away from the pump barrel.

Abstract: An apparatus and method for specialized shaped charges that perforate similar sized diameter holes regardless of the fluid gaps between the shaped charge and the casing wall. Shaped charges having three conical or frusto-conical liner sections are disclosed, where the apex liner section has a larger conical angle than the outer liner section are disclosed.

Abstract: A positioning device includes a shaped charge holder. A plurality of shaped charge receptacles formed in the shaped charge holder are configured to arrange a plurality of shaped charges in a desired orientation. The shaped charges are detonated by a detonator in response to an initiation signal. The positioning device may be secured in a perforating gun module, with vertical and horizontal movement of the positioning being inhibited in the perforating gun module.

Abstract: There is provided an oil pumping apparatus including: (1) a connector connected to a device; (2) a top platform; (3) a roller disposed on a top platform; (4) a motor disposed on the top platform; (5) a driven belt to enable synchronous drives to operate the roller; (6) a load belt moveable over the roller, one end of the load belt being connected to the connector, and the other end of the load belt being connected to a balance box to balance the weight of the device; and (7) a control system for the apparatus. When the motor rotates in a clockwise direction, the motor drives the roller rotate in the clockwise direction and the device moves down vertically; and when the motor rotates in an anticlockwise direction, the motor drives the roller rotate in the anticlockwise direction and the device moves up vertically.

Abstract: A method for drilling a wellbore in the formation, wherein the wellbore is approximately horizontal; forming two or more fractures in the formation from the wellbore; receiving fracture performance data about the two or more fractures; analyzing the fracture performance data; selecting one or more fractures for injection and selecting one or more fractures for production based on the analysis of the fracture performance data; and completing the wellbore such that injection into the one or more fractures selected for injection and production from the one or more fractures selected for production may occur simultaneously.

Abstract: A method of hydraulic fracturing of an oil producing formation includes the provision of a heating apparatus which is transportable and that has a vessel for containing water. A water stream of cool or cold water is transmitted from a source to a mixer, the cool or cold water stream being at ambient temperature. The mixer has an inlet that receives cool or cold water from the source and an outlet that enables a discharge of a mix of cool or cold water and the hot water. After mixing in the mixer, the water assumes a temperature that is suitable for mixing with chemicals that are used in the fracturing process, such as a temperature of about 40°-120° F.+(4.4-48.9 C+). An outlet discharges a mix of the cool and hot water to surge tanks or to mixing tanks. In the mixing tanks, a proppant and an optional selected chemical or chemicals are added to the water which has been warmed.

Abstract: According to examples, system control may include accessing a plurality of procedures to control an operation of a system to prevent an occurrence of a fault in the system and/or a reduction of an output of the system. A highest ranked procedure may be learned from the plurality of procedures to control the operation of the system to prevent the occurrence of the fault in the system and/or the reduction of the output of the system. Real-time data associated with the system may be accessed. Further, the operation of the system may be controlled by applying the highest ranked procedure to prevent the occurrence of the fault in the system and/or the reduction of the output of the system.

Abstract: A method of modeling hydrocarbon flow from a fractured unconventional reservoir, where the formation has variability in stimulated reservoir properties caused by multi-stage fracturing treatment. A map is created which divides the formation into a plurality of closed production regions, each of which in turn is divided into a plurality of flow sub-systems extending between fractures in the formation. Production behavior is then calculated for each flow sub-system based on the geography and characteristics of the individual flow sub-system. Region hydrocarbon flow for each closed production region is determined by coupling the calculated production behavior of the flow sub-systems and the reservoir hydrocarbon flow can be modeled by aggregating the region hydrocarbon flows. Type curves showing the modeled hydrocarbon flow at selected points in time can then be plotted.

Abstract: The present invention relates to a downhole stimulation system for stimulating production. The system has first and second inflatable packers (6) for isolating a production zone (10), the packers being inflated through aperture (15), a sliding sleeve valve (17) arranged between the two packers, the sleeve having an opening (19) to provide fluid communication between the inside of the well tubular and the production zone. In operation the inflatable device is set downstream of the inflation aperture of the lower packer, the well is pressurized to move the tool downstream to open the sliding sleeve valve, whereafter fracturing fluid with proppants having a size which is smaller than that of the sliding sleeve opening (19) and larger than the packer inflation aperture (15), is pumped downhole using a displacement means such as a piston element.

Abstract: Methods and systems for facilitating extraction of subterranean hydrocarbons from a geologic structure. The present methods include causing corrosion of a base metal within a geologic structure to produce a gaseous product to increase pressure and form fractures in the geologic structure. Some embodiments of the present methods include injecting a fluid composition comprising the base metal into a wellbore (e.g., into a geologic structure via the wellbore).

Abstract: Methods and apparatus of pressure activated completion tools for hydraulic fracturing and related processes are provided. In some embodiments, the hydraulic fracturing apparatuses for accessing a subterranean formations can include a tubular body to be fluidly connected in-line with a completion string, the tubular body having at least one burst port configured to receive burst inserts (burst plugs), and a movable inner sleeve that can slide along the inside of the tubular body when exposed to hydraulic pressure from a first position to a second position. The tubular body can also have flow-port(s) that are blocked when the movable inner sleeve is in the first position and opened when the movable inner sleeve slides to the second position.

Abstract: A bladeless conical radial rotary machine method and system are disclosed. Turbo-machinery and methods are disclosed for a bladeless conical radial rotary machine wherein fluid is directed axially within the pump body to produce an axial output. The rotor comprises a plurality of spaced apart conical elements. The fluid is smoothly directed to any number of subsequent boundary layer pumping stages which are axially positioned with respect to each other. The fluid is smoothly directed to any number of subsequent boundary layer pumping stages which are axially positioned with respect to each other. A coupling between pumping stages is disclosed.

Abstract: The present disclosure is directed to systems and methods for rotating a drill string to mitigate stick-slip oscillations. An embodiment includes a method of rotating a drill string driven by a drive system using a control system. The method includes measuring torque values of the drive system with a torque sensor. The method also includes determining a frequency of stick-slip oscillations at the drive system based on the torque values using the control system. The method also includes determining an estimated instantaneous rotational speed of the drive system with the control system based on at least the frequency of stick-slip oscillations and a characteristic impedance of the drill string. The method also includes adjusting the estimated instantaneous rotational speed based on changes in the torque values to define an adjusted estimated instantaneous rotation speed with the control system.

Abstract: Monitoring one or more items of equipment associated with a borehole or other conduit. A sensor system includes a vibration sensor for sensing vibrations at one or more sensor locations associated with one or more items of the equipment and/or the borehole or other conduit. A processing system processes the sensor information to determine a characteristic of the operation of the one or more items of equipment and/or the borehole or other conduit.

Abstract: The current subject matter provides a tool and user interface for estimating a velocity at which a plunger of a rod lift pump system will impact a fluid within a well when the rod lift pump system is altered to operate under various conditions of pump fillage. In some embodiments, the estimated impact velocity can be determined using a velocity pattern characterizing a velocity and position of a plunger of a rod lift pump system operating under a condition of complete pump fillage. The estimated impact velocity can provide a user with useful insight into potential operation of the rod lift pump system when operating under various conditions of pump fillage.

Abstract: A technique facilitates protection of a sensitive component, e.g. a well tool component, against shock and vibration. The sensitive component may be positioned in a mechanical chassis which is mounted in a housing. The mechanical chassis is mounted in the housing via a damper system which may comprise various vibration and shock absorbing components, such as a vibration damper, a transverse shock damper, and/or an axial damper. In drilling applications, the housing may be coupled into a drill string although the damper system may be used in other types of applications.

Abstract: A system for guiding a well comprises a current source, a ground terminal electrically connected to the current source and grounded at the surface of the Earth, a reference wellbore comprising an intermediate casing (IC) that includes an IC electrical discontinuity and is electrically conductive between that the IC discontinuity and the IC bottom hole, a reference conductor electrically connected to the current source, a tubular that includes a tubular string electrical discontinuity (TSED), is electrically conductive between the TSED and the tubular bottom hole end (TBHE), and is inserted into the reference wellbore through the IC. Electrical connections exist between the tubular, the reference conductor, and the reference wellbore between the TSED and the TBHE, whereby current flowing through the reference conductor produces a magnetic field; magnetic sensors to sense the magnetic field and a guided wellbore is steered in response to the sensed magnetic field.

Abstract: The invention relates to DAS observation has been proven to be useful for monitoring hydraulic fracturing operations. While published literature has shown focus on the high-frequency components (>1 Hz) of the data, this invention discloses that much of the usable information may reside in the very low frequency band (0-50 milliHz). Due to the large volume of a DAS dataset, an efficient workflow has been developed to process the data by utilizing the parallel computing and the data storage. The processing approach enhances the signal while decreases the data size by 10000 times, thereby enabling easier consumption by other multi-disciplinary groups for further analysis and interpretation. The polarity changes as seen from the high signal to noise ratio (SNR) low frequency DAS images are currently being utilized for interpretation of completions efficiency monitoring in hydraulically stimulated wells.

Abstract: A system that is positionable in a wellbore can include a transceiver that is positionable external to a casing string and programmable to vary a number of data packets that are wirelessly transmitted by the transceiver. The number of data packets can correspond to an amount of data wirelessly transmitted by the transceiver about an environment in the wellbore.

Abstract: Apparatus, systems, and methods may operate to correct measured resistivity data for borehole effects to provide borehole-corrected apparent resistivity data for a non-invaded formation. Additional activity may include inverting the measured resistivity data or the borehole-corrected apparent resistivity data to provide non-invaded true resistivity values for the non-invaded formation, inverting the measured resistivity data to provide invaded true resistivity values for an invaded formation, determining true resistivity values for a geological formation associated with the measured resistivity data as a weighted combination of the non-invaded true resistivity values and the invaded true resistivity values, and operating a controlled device according to the true resistivity values for the geological formation.

Abstract: A method can include receiving acoustic emission data for acoustic emissions originating in a formation, performing a moment tensor analysis of the data, thereby yielding acoustic emission source parameters, determining at least one acoustic emission source parameter angle having a highest number of associated acoustic emission events, and calculating an in situ stress parameter, based on the acoustic emission source parameter angle. A system can include multiple sensors that sense acoustic emissions originating in a formation, and a computer including a computer readable medium having instructions that cause a processor to perform a moment tensor analysis of the data and yield acoustic emission source parameters, determine at least one acoustic emission source parameter angle having a highest number of associated acoustic emission events, and calculate an in situ stress parameter, based on the acoustic emission source parameter angle.