668 results about "Sluice" patented technology

A subcutaneous needle conduit attaches directly to a blood vessel or other biological boundary structure. The subcutaneous needle conduit is tapered such that a proximal end is wider than a distal end. A body of the subcutaneous needle conduit guides the tip of a needle or other canula from the proximal end to the distal end. The subcutaneous needle conduit may be funnel-shaped. An elongated funnel shape may be used to selectively provide access to a plurality of desired access sites along an axis of a blood vessel. Other shapes, such as sluice-shaped, may also be used. The subcutaneous needle conduit may be located beneath the skin surface using, for example, tactile sensation, magnetism, metal detection, detection of a signal emitted from a minute transponder, detection of light emission, or through other detection methods.

The invention discloses a reservoir, sluice and pump cluster combined saltwater tide control and scheduling method. The method comprises the following steps of: S1. establishing a Pearl River basin distributed hydrological model based on EasyDHM; S2. establishing a backbone reservoir cluster saltwater tide control and scheduling model; S3. calculating a flow process of a key node of the basin by utilizing the Pearl River basin distributed hydrological model based on EasyDHM, and inputting the flow process into the reservoir cluster saltwater tide control and scheduling model, thus obtaining a flow control process of a downstream key section through the model; and S4. determining a draining sluice, a freshwater releasing for water replenishing and saltwater tide control time and a draining saltwater tide control flow by utilizing a sluice and pump cluster freshwater releasing for water replenishing and saltwater tide control scheduling model. The reservoir, sluice and pump cluster combined saltwater tide control and scheduling method analyzes the runoff characteristics of the Pearl River basin in a dry season, forecasts the inflowing process of the key section of the basin during a drought period, and establishes an optimized scheduling model for the backbone reservoir cluster of the basin, thus achieving the coupling, nesting and rolling correction of real-time scheduling schemes on the basis of optimizing the scheduling schemes, overcoming the disadvantages brought by a deterministic scheduling model, and greatly improving the utilization rate of water resources during a scheduling period.

An apparatus for the cleaning of a turbine engine comprises a towable wash cart having a reservoir for cleaning fluid. The reservoir is connected through a pump system to a wash ring operatively mounted to the cart. The wash ring has a plurality of spray nozzles about its periphery arid positionably adjustable for directing an atomized spray of the cleaning fluid into an inlet of the engine. The cart and wash ring is aligned with the engine such that there is no physical contact between the wash ring and engine during the entirety of the cleaning process. While a preferred cleaning fluid is pure water, the reservoir may be segmented to carry a number of different cleaning solutions, which can be mixed in a manifold of the pump system as may be desired for a particular cleaning process. The reservoirs may be heated and insulated to maintain the cleaning solutions at an elevated temperature. A sluice cart may be provided to collect cleaning fluid draining fur the engine for delivery to a collection tank on the wash cart.

This application relates to a method and system for tracking and managing a cargo container. The system comprises an electronic seal device mounted on the cargo container, a portable device, a fixed device provided on sluice door, a guide device and a computer bound thereof, and a background management center system. The method and system for tracking and managing the cargo container according to the present invention can realize visible and transparent tracking, monitoring of any cargo container, such that risky and dangerous cargo containers can be effectively selected for a particular sampling inspection to ensure the shipment safety of the cargo container and realize the international antiterrorism of the cargo containers.

The invention discloses a valve torque continuous test device which is used for testing torque when a valve (1) is opened and closed. The test device comprises a valve drive mechanism (2), a torque sensor (3), a valve opening data acquiring system (4) and a computer operation control system (5), wherein the torque sensor (3) is arranged at the connecting position of the valve drive mechanism (2) and the valve (1). The invention also discloses a corresponding test method which can continuously test the opening and closing torque of a butterfly valve, a ball valve and a sluice valve in a torque range and the dynamic torque thereof in the opening and closing process. The precision of the torque sensor is 0.5 percent; a measuring error of a torque test system is smaller than or equal to 1 percent; the device can display a torque value of any opening position in the opening and closing process of the valve and output and print a curve graph of the valve opening position corresponding to a torque valve; and the device can adopt an electric drive way and a manual drive way which are in mutual noninterference.

The invention relates to a method for culturing finless eel and freshwater crayfish in a pond, which includes (1) selecting pond or low-level pond, or opening ditches such as 'curve', 'well' or 'field' font, keeping sluice above 1.5m in the pond or ditch; (2) clearing and sterilizing the pond, keeping the water depth for 30cm, fertilizing and planting aquatic; (3)the net box of finless eel being an open style, planting water peanut in the box; (4) regulating water quality by stocking silver carp and bighead carp, putting healthy fingerlings of the freshwater crayfish one off in the last decades of April (100kg / 666m2), or putting mature fingerlings of the freshwater crayfish whose female and male ratio is 2:1 in the autumn; (5) stocking young finless eels from the last ten-day of April to the first ten-day of May or the last decades of July (1kg / m2); (6) feeding food per day, the amount of which are 5-8% of the weight of freshwater crayfish; (7)subduing feeds after young finless eels are put in the box and hungry for 3 days, the weight ratio of minced earthworm or fresh fish and finless eel is 5:1, 4:1, 3:1 and 2:1; (8) strengthening water quality management, fertilizing management and prophylaxis osamu work of the aquaculture water and inside the net box.

The invention discloses a deformation monitoring and state early-warning method for a hydraulic structure of a sluice station, thereby determining operation state of the hydraulic structure, performing real-time early warning on unsafe states and ensuring safe operation of water conservancy project. The method particularly comprises the steps of a step of selecting an engineering monitoring point; a step of acquiring monitoring information; a step of analyzing and comparing monitoring information; a step of processing an analysis result; and a step of performing state early-warning. The deformation monitoring and state early-warning method can realize functions such as issuing monitoring information and data analysis result and engineering state early-warning; real-time analysis is performed on the safety of a sluice and a pump station building so that personnel masters the deformation amount of the building in time and analyzes the change trend; furthermore a suggestion is brought forward for engineering management, engineering inspection and engineering maintenance, thereby ensuring safe operation of engineering equipment; and furthermore the personnel monitors the engineering state of the sluice station by means of terminal equipment, thereby facilitating management operation for the sluice station and improving operation efficiency.

The inventors have reached the idea of a film formation apparatus including a film formation chamber, a removal chamber, two sluice valves provided apart from each other between the film formation chamber and the removal chamber, and a shadow mask transfer mechanism. The film formation chamber includes an evaporation source, and the removal chamber includes a parallel plate plasma source and a shadow mask stage. The film formation apparatus has a film formation mode in which a shadow mask overlapped with an object is transferred by the shadow mask transfer mechanism and a film is formed on the object; and a cleaning mode in which the shadow mask is irradiated with plasma by the plasma source, the shadow mask being held between an upper electrode and a lower electrode by the shadow mask stage.

A dewatering conveyor system for dewatering chunks of petroleum coke or the like material which is mixed with large volumes of water, wherein the conveyor employs lateral drag bars, the top flight of which conveyor slides forwardly on a screening deck having dewatering screens, and the bottom flight of which conveyor slides rearwardly on a sluice deck underlying the screening deck, wherein a major portion of the conveyor rearward of its discharge end is contained by tail end wall means and side and bottom wall means which can contain large volumes of coke and water, wherein, for handling large volumes of water the discharge end of the conveyor is elevated, e.g., up to 20 ft. or more above the tail end of the conveyor such that water dropping thru the screens will run down toward the tail end of the conveyor and leave the discharge end above the water line, and wherein a drain port is located thru the bottom wall means at a tail end portion thereof.

There is provided with a complex ocean power system combining ocean current power generation for generating electricity by forming a plurality of ocean current generators in front and rear of sluice structures of tidal power dams and sluice power generation for generating electricity by forming a plurality of ocean current generators in sluice conduits of the sluice structures, comprising: constructing barrages, which cross over the sea, to make up a lake; installing sluice structures of tidal power dams between the barrages 10 to generate electricity by changing a potential energy difference between seawaters caused by tides and ebbs to kinetic energy; installing ocean current generators in front and rear of the sluice structures and in the sluice conduits of the sluice structures to generate electricity by rotating turbine blades using the flow of the incoming seawater from a sea side into a lake side during flood tide and the flow of the seawater discharged from the lake side into the sea side during ebb tide; and installing sluice gates in the sluice structures 102, 210 to close and open the sluice conduits during flood tide and ebb tide.

The invention relates to a general accurate grinding clamp with an adjustable sluice valve flashboard and belongs to the technical field of machining. The general accurate grinding clamp comprises a wedge angle slope moldboard with an upper surface provided with a workpiece, one end of the wedge angle slope moldboard is used for fixing a retaining plate for limiting the workpiece, and two sides of the wedge angle slope moldboard are provided with compression bolts for pressing and holding the workpiece through pressing plates. The general accurate grinding clamp is characterized in that one end of the wedge angle slope moldboard for fixing the retaining plate is hinged onto a base plate, one end of the wedge angle slope moldboard far away from the retaining plate is padded on an adjusting base plate with preset slope, and the lower ends of a locking bolt penetrating through the adjusting base plate and an adjustable bolt screwed on the adjusting base plate are respectively connected with and support on the base plate. When the flashboard to be machined is placed on the wedge angle slope moldboard, the retaining plate can be used for locating, the pressing plates can be used for pressing and fixing, when the angle of inclination needs tuning slightly, users can only screw the adjustable bolt, change hinged inclination of the wedge angle slope moldboard and then adjust, the locking bolt is used for locking, and the general accurate grinding clamp is convenient.

The invention discloses a preparation method of a spectrum standard sample for 1420 aluminum lithium alloy, which comprises the following steps: performing composition design, and weighing corresponding raw materials for melting according to the designed mass ratio; putting the raw materials for melting into melting equipment for melting; performing sampling analysis after melting, according to the analysis result, adjusting chemical components by adopting the method of adjusting chemical components step by step, finally adjusting the element Li, and adopting a solvent including LiF and LiCl for covering during adding Li; refining by adopting argon before casting, protecting a sluice by adopting argon during casting, and taking a segregation test piece and a metallographical test piece from a cast ingot by cutting for test; performing peeling, homogenization heat treatment and extrusion on the cast ingot conforming to the standards, and cutting the bar material formed through extrusion to obtain a standard sample. Through the adoption of the standard sample prepared through the method, the chemical component analysis and composition control on the 1420 aluminum lithium alloy can be realized, particularly the content of Na can be accurately tested, and the calibration standards can be provided for the normal production and quality inspection of aluminum lithium alloy.

The invention relates to a device system for online monitoring pressure and flow of supplied water in real time, which comprises a monitoring control center by wireless signal transmission and monitoring control stations dispersed and arranged for each water customer; and the monitoring control station comprises a remote signal transmission water meter (2), an intelligent data collector (3), a water guide electromagnetic valve (11), a remote control water power valve (12), a microwave data transmission radio station (6) or a GPRS / CDMA (21), a pressure sensor (4), a single input digital displaying instrument (5), a power supply I, a programmable controller (8), a sound and light alarming device (10), a common sluice valve (17), a bypass valve (18) and the like. The monitoring control center comprises a power supply II, the microwave data transmission radio station (6) or an Internet (22), an industrial controller operating software (9), the programmable controller (8), the sound and light alarming device (10) and the like. The device system can realize the functions of monitoring the pressure and flow of the supplied water of the water customer on line in real time, pre-charging water fee of the customers, automatically descending the water fee along the accumulated water consumption amount of the customer, reminding the customer of paying the water fee in advance, automatically cutting off the water supply by remote control when defaulting, automatically supplying water by remote control after payment and the like.

A sluice assembly for separating heavy particles from slurry is provided. The sluice assembly includes one or more sluice boxes having decks made of plastic having a Shore D hardness between 50-75, a static coefficient of friction less than 0.3 and a kinetic coefficient of friction less than 0.2. In a preferred embodiment, the sluice assembly includes a pair of sluice boxes in which a top sluice box is positioned above the bottom sluice box so that slurry flowing from the downstream end of the first sluice box is received by the upstream end of the bottom sluice box. The bottom deck includes tapered riffles which are arranged to provide “V” shaped diverters for diverting heavier particles for collection. The sluice box upper deck may include laterally extending riffles for collection of heavier particles.

A machine is employed for recovering heavy metals and precious or semi precious minerals, such as gold, copper, lead, diamonds, and garnets from placer, or hard rock ore. The machine employs a cylindrical, annular outer drum mounted for rotation at an inclination to the horizontal and including at least one spiral vane extending the length of its inner surface. A cylindrical, annular inner barrel is mounted within the drum and has an upper fragmentation section, an intermediate screened section, and a lower discharge section. A spray of water is directed into the inner barrel and a water spray bar is located in the annulus between the inner barrel and the outer drum. A fine sluice box is located to receive under one-quarter material input from a side trommel and a coarse sluice box located to receive discharge from the side trommel and discharge from the fine sluice box. The sluice box includes a plurality of landings, matting and screens upon which heavy materials, such as gold or precious stones, collect.

This invention discloses ocean tide power generation equipment and method, which contains V-shape check dam, overtopped dam, water storage reservoir, drainage reservoir, water intake gate, drainage sluice and power generator set. When the ocean is on the tide, open intake gate, close sluice in ebb, use the water level difference to generate electricity. Said V-shape check dam can collect sea water as the tide is small. Said invention has low cost and stable operation.

The invention discloses a siphoning type reservoir desilting and screening device and a use method of the siphoning type reservoir desilting and screening device. The siphoning type reservoir desilting and screening device comprises a swinging and stirring mud sucking nozzle, a mud sucking state sensor, a water power depositing material screening device and the like. A row of anchor blocks which are vertical to the axis of a dam are arranged on an upstream dam slope, a dam top and a downstream dam slope of the reservoir dam. Water sucking pipes and mud sucking pipes are installed on the anchor blocks in parallel. Mud sucking hoses are loaded on a row of floating boats on the water surface of the water reservoir. The mud sucking state sensor is arranged on the suspended ceiling part of a derrick mast of the head of a powerboat, a steel wire rope penetrates through a fixed pulley which is connected with the mud sucking state sensor to lift and sink the swinging and stirring mud sucking nozzle to the sediment deposit layer at the bottom of the water reservoir. A water power depositing material screening device, a material field, a depositing pool, a water diversion sluice and a water diversion canal are arranged at the foot of the downstream dam. The siphon principle is used by the siphoning type reservoir desilting and screening device to perform desilting on a reservoir zone, power is provided for the depositing material screening device and the screened sand and gravel materials are used as construction materials. Water is introduced into the canal for irrigation. The siphoning type reservoir desilting and screening device can reasonably utilize water resources and protect the water environment.

The invention provides a parking lot parking monitoring identification system and a method thereof. The system comprises a backstage server, a wireless communication module, at least one entrance camera which is fixedly arranged at an entrance of a parking lot, multiple aisle cameras fixedly arranged in a parking lot aisle, and an entrance sluice. The entrance camera captures a license plate number according to a license plate image capturing instruction output by the entrance sluice and forms entrance license plate image information and outputs the information to the backstage server, and the backstage obtains entrance vehicle license plate number information according to the entrance license plate image information; multiple aisle cameras output real-time image information to the backstage server, and the backstage obtains aisle vehicle license plate number information according to the real-time image information; the backstage server compares the entrance vehicle license plate number information with the aisle vehicle license plate number information to obtain vehicle parking location information corresponding to the vehicle information. In this way, automatic matching identification of license plate numbers and corresponding parking space information in the parking lot is achieved, and then the identification is regarded as a basis for reversely seeking vehicles in an intelligent parking system.

The invention provides a drainage structure for controlled drainage of a tunnel and a tunnel drainage system with the same. The drainage structure for controlled drainage of the tunnel comprises two drain pipes, wherein the two drain pipes are connected and the diameters of the two drain pipes are different. The diameter of the drain pipe A is smaller than the diameter of the drain pipe B. One end of the drain pipe A is sealed, and the sealed end of the drain pipe A stretches into the drain pipe B. The drainage structure further comprises a spring, the spring is fixedly connected with the bottom of the sealed end of the drain pipe A, a sluice valve block matched with the cross section of the drain pipe A in size is arranged at the movable end of the spring, a plurality of water outlets are formed between the bottom end of the drain pipe A and the sluice valve block, and the sluice valve block is connected into the drain pipe A in a sliding mode through a plug. The drainage structure and the tunnel drainage system with the drainage structure are simple, have the moderate drainage effect, can further ingeniously eliminate calcium crystals (or suspended sediment) adhering to the inner portions of the drain pipes, and are high in operability, wide in practicability and capable of effectively promoting the development of drainage systems of tunnels which are high in ecological system requirement or tunnels in limestone areas.

The invention provides a one-dimensional river network generalization and high-performance one-two-dimensional coupled flood analysis method, comprising the steps of establishing a one-dimensional river network model, a confluence type unit model, a whole basin river network coupling model and a two-dimensional shallow water model. Zero-dimensional storage and nodal equations are computed, and control condition model elements are selected. The control effects of weir, sluice and pump on flow are analyzed by using control condition model elements. When the two-dimensional shallow water model isnumerically discretized, the position of variables in the computational grid is determined, and the flux, bottom slope source and friction drag source in the two-dimensional shallow water model are calculated. A spatial second-order accuracy scheme is constructed and a variety of boundary conditions are set. According to the data, a set of flood control control system is formed, and the numericalsimulation of the operation mode of engineering control is carried out to achieve the effective simulation and forecast of flood.

The invention provides a tide-sensitive river network water environment treatment method based on an MIKE model, and the method comprises the following steps: step 1, establishing a river network model based on MIKE, and improving the stability and precision of the model through a method of space step length control, terrain recheck and group gate assignment operation through a time sequence; step2, determining a water replenishing and activating scheme; and step 3, determining a water supplementing process and a water supplementing amount. Complex water flow characteristics of a tidal rivernetwork are used; an HD of an MIKE11 model is used; the AD module constructs a one-dimensional hydrodynamic force and water quality model; the model can directly determine the planned flow of the sluice and the pump station and the flow and concentration of a pollution source afflux point; outputting a water level process line of each section of the river and a process line of pollutant concentration; decision bases are provided for implementation and arrangement of water replenishing and flowing water and river regulation projects in a river network area, tidal power and existing sluice dispatching and water replenishing are fully utilized, the project operation cost is low, implementation is facilitated, river surges are connected into a whole, the river surge water environment is improved, and meanwhile flood regulation is facilitated.

The method is for feeding a chips-slurry from a low-pressure to a high-pressure system during the continuous cooking of chemical cellulose pulp. The feed takes place through a sluice feeder 53′ between these systems. The sluice feeder is provided with a rotor with through-pockets 1, 2 that are alternately connected with the low- or the high-pressure system. A recirculation line 54′, that has a high-pressure pump 57′, extends from the first outlet 53b′ of the sluice feeder to the second inlet 53c′ of the sluice feeder for transporting the fluid that has been expelled from the pockets of the sluice feeder when these are located in their first position. The fluid expels the chips mixture from the pockets of the sluice feeder in their second position and is essentially exclusively constituted by the fluid that has been expelled from the pockets in their first position.

The invention relates to an automatic tapping machine for valve-connected nut of sluice valve, which is characterized by mainly consisting of a bed body, a main axis provided with a workpiece clamping mechanism, a transmission, as well as a middle carriage and a small carriage which are respectively fixed with an air cylinder; the small carriage is fixedly provided with a tool rest; the tool rest is fixedly provided with a tool; the main axis is supported on a headstock and is connected with the transmission mechanism. The automatic tapping machine for valve-connected nut of sluice valve has the beneficial effects of being suitable for producing common civil sluice valve, being capable of reducing the cost, improving the work efficiency, and adapting the demand of very low market price. 4,500 nuts can be produced for worker in single shift.

The invention is a hydraulic controllable gate valve, belonging to a hydraulic driven gate valve, applied to water feeding and discharging engineering and comprising a main body and an auxiliary hydraulic pumping station; the main body comprises valve body, hydraulic motor, connection frame, drive nut, screw rod, clamp ring and copper cover; the hydraulic motor is connected with the drive nut through spline, the drive nut is axially located through the clamp ring and connection frame, and the hydraulic motor and the clamp ring are both fixed on the connection frame; the screw rod is connected with the drive nut through spiral auxiliary; the auxiliary hydraulic pump station comprises oil tank, hydraulic pump, electromagnetic directional valve and overflow valve; the inlet of the hydraulic pump is connected with the oil tank and its outlet is connected with the mouth P of the electromagnetic directional valve, the hydraulic motor is connected with mouths A and B of the electromagnetic directional valve, and the overflow valve is connected with the outlet end of the hydraulic pump.

The invention discloses a steel hydraulic river sluice which comprises a control system and a plurality of sluice gate units. Each sluice gate unit comprises a secondary concrete sluice gate groove, amain anchor bolt embedded part, a sluice gate body, a sensor, an oil cylinder, a swing oil cylinder, a hydraulic system and a limiting switch. All the sluice gate bodies harmoniously move on the whole. According to the river sluice, rising and falling of the multiple sluice gate units are automatically controlled; during outage caused by flooding, hydraulic oil can be pressed back to an oil tankthrough the self-weight of water, and the water level is controlled to achieve safe flood discharge; through the combined-type design, the installation process is simplified, no middle sluice pier isneeded, and maintenance is easy, convenient and feasible; the arc-shaped sluice gate bodies and a stiffened plate can effectively smoothen a water flow; the sluice is supported through the oil cylinders and the swing oil cylinders, and a foundation is simple; no mechanical bearing is needed, no guiding groove is needed so that a water seal cannot be blocked by sand entering of the guiding groove,and no space is occupied by a hydraulic arm; and information collected by the sensors is transmitted to the control system, and the control system sends an instruction to the hydraulic systems to automatically control the oil cylinders to adjust the elevation angles, namely the water retaining heights, of the sluice gate bodies.

The invention discloses a method of measuring floodgate opening. The method comprises the steps of arranging a position switch along the position where a hoist drive gear is lifted or lowered, the position switch together with a counter of a measuring device composes a counting circuit to acquire the tooth number of the gears; the position acquires a position limit signal when the floodgate is fully opened or closed; when the floodgate is lifted or lowered, the measuring device transforms the rotation tooth number of the host drive gear to floodgate opening through opening calculation according to a tooth number signal, the position limit signal and a lifting or lowering signal. When the measuring device obtains the signals that the floodgate is fully opened or closed, the counter resets. The method of measuring floodgate opening is easy to measure, high in precision, less in error and is convenient and easy to operate, which is particularly suitable to measure the opening of dam floodgate.

The invention provides an anti-freezing liquid interior pressure difference transfer control valve which comprises a valve body and a valve core comprising a control chamber. The valve core part moves vertically along a valve lever shaft in the valve body. The valve body comprises a handwheel, a screw, an upper valve cover and a lower valve cover and is provided with a liquid inlet, a liquid outlet and a middle opening that are communicated; the middle opening of the valve body is connected with the bottom of the lower valve cover in a sealing manner, the axis of the liquid inlet of the valve body and the axis of the liquid outlet are distributed at a certain angel; the valve core comprises a pair of liners of the same shape, a lower patch, a seal sleeve, a valve lever, a large valve plate, a lower patch and a small valve plate, wherein, the valve lever can move freely relative to the central direction of a sealing opening at the middle of the main valve body. The transfer control valve has the advantages that the control valve is especially suitable for the working environment with an external temperature of the valve lower than 0 DEG C; when a pump is started, a sluice is closed and the valve is opened slowly strictly according to the operation rules of the pump, and when the pump is stopped, the large valve plate is first closed, keyholes at the circumference of the small patch are relieved from pressure, the small valve plate and the valve lever are pulled slowly downward to be closed; therefore, the control valve is not afraid of freezing environment, completely removes liquid breakdown and fulfills automatic control and sealing non-return without an external motive force.

The invention discloses a colloid mill stator and rotor and a colloid mill comprising the stator and rotor, and belongs to the field of machinery. According to the colloid mill stator and rotor provided by the invention, the end surface of a stator disc and the end surface of a rotor disc are provided with concentric annular distribution toothed sections; a sluice channel is formed between adjacent toothed sections; straight teeth are arranged on the toothed section at the outermost layer of the end surface of the static disc; trapezoidal teeth are arranged on the toothed sections at the other layers of the end surface of the stator disc; the tooth height of each straight tooth is smaller than the tooth height of each trapezoidal tooth on the end surface of the stator disc; a blind groove is formed in the outer edge of the sluice channel between two adjacent straight teeth; inclined teeth are arranged on the toothed section at the outermost layer of the end surface of the rotor disc; trapezoidal teeth are arranged on the other various layers of the end surface of the rotor disc; the tooth height of each inclined tooth is smaller than the tooth height of each trapezoidal tooth of the end surface of the rotor disc; and a blind groove is formed in the inner edge of the sluice channel between two adjacent inclined teeth. The colloid mill comprising the stator and rotor disclosed by the invention is simple in structure, high in shearing efficiency and long in service life.