208 results about "Container crane" patented technology

The invention discloses a large container crane intelligent early warning system based on personnel behavior analysis, and the system comprises the following steps: collecting operator behaviors, equipment operation states and environment parameters in real time through a multi-mode sensor network, constructing a dynamic data set, extracting behavior characteristics through a time difference embedding algorithm, and carrying out the early warning of the operator behaviors, the equipment operation states and the environment parameters; a multi-level spatial-temporal characteristic matrix is generated in combination with dynamic scene influence factors, regional risk factors are dynamically calculated by using a Bayesian inference model, comprehensive risk values are generated through an adaptive multi-objective optimization algorithm, risk levels are divided into low, medium and high classes, and a system triggers graded early warning responses according to the risk levels. And an optimized behavior adjustment suggestion is generated in combination with a quantum probability behavior prediction algorithm, and a feature extraction rule and risk assessment logic are dynamically optimized through a progressive learning algorithm to form a closed-loop optimization process. According to the invention, intelligent analysis and real-time early warning of personnel behaviors are realized, and the safety and adaptability of the crane in an operation environment are improved.

The invention discloses a steel wire rope derailment early warning method and system for a container crane pulley block, and the method comprises the steps: collecting real-time images of the pulley block and a steel wire rope, and achieving the automatic monitoring of the operation state of the steel wire rope through feature point detection and geometric transformation estimation; and by utilizing the structural knowledge of the pulley block, accurate derailment detection is carried out under the condition of a small number of samples or even almost no samples, so that the cost of data preparation and model training is reduced. The method is easy to control, a user only needs to manually specify masks of a pulley area, a cross beam area and a steel wire rope area and mark key structure feature points, the system can automatically extract features and perform subsequent automatic detection, and the method has good user friendliness and adaptability.

The utility model provides a port container crane which comprises a fixed frame, a movable frame is arranged at the front end of the fixed frame, pulleys are mounted at the bottom of the movable frame, two groups of rolling seats are mounted at the top of the fixed frame, rolling shafts in the rolling seats are in transmission connection through shaft rods, and sliding blocks are driven by bidirectional electric push rods to slide along a transverse frame. The transverse distance between the hooks and the lifting rope is adjusted, the first inserting rod and the second inserting rod are moved along the interior of the sliding frame, and then the distance between the side faces of the hooks is adjusted by fixing the extending lengths of the first inserting rod and the second inserting rod through bolts. The container is lifted and hoisted through the winding seat, then the rotating frame rotates from the vertical state to the horizontal state, the movable frame moves outwards, the hoisting assembly and the container are driven to move outwards, the container is conveniently conveyed to a transfer vehicle, and then the hoisting efficiency of the container is improved.

The invention relates to the technical field of port container crane grab bucket control, and particularly discloses an anti-swing grab bucket for port portal crane hoisting and an anti-swing method. The grab bucket posture detection mechanism can detect the posture of the hoisting grab bucket, the horizontal shaking preliminary reduction mechanism, the hoisting point adjusting mechanism and the horizontal shaking secondary reduction mechanism can restrain horizontal shaking of the hoisting grab bucket, and the winding and unwinding mechanism and the torsion detection mechanism can restrain vertical shaking of the hoisting grab bucket. The rotating and shaking hindering mechanism can restrain rotating and shaking of the lifting grab bucket, and all-directional shaking control can be conducted on the grab bucket in different shaking scenes through combination of the three.

The invention provides an operation safety early warning method and device for a special crane for a rail-mounted container, and relates to the technical field of crane operation safety, and the method comprises the following steps: integrating an unmanned aerial vehicle and an image monitoring module to obtain a multi-view image; the virtual reality technology is applied, the traction part of the special crane for the rail type container serves as the center, the visual range is expanded, environment information is overlaid, and a safe area and obstacle marks are obtained; constructing a monitoring sensor network, monitoring each part of the crane in real time, acquiring synchronous data and predicting maintenance requirements; and setting a dynamic control interval by using fuzzy logic, and establishing an operation safety early warning model for decision making. The method can solve the problem that in the prior art, potential safety hazards in the working environment cannot be comprehensively captured, safety areas and obstacles are difficult to recognize in real time, and consequently recognition of the potential safety hazards in the working environment is inaccurate, real-time monitoring of all parts of the special crane for the rail type container is achieved, and the working efficiency is improved. And the maintenance demand is predicted through data analysis, so that the timeliness and accuracy of maintenance are improved.

A full-unit lifting method for a quayside container crane includes calculating an overall center position of gravity of the quayside container crane full-unit; estimating a lifting height and a floating amplitude required by a main hook of a floating crane according to a water level differential at a dock and a height of the quayside container crane full-unit; selecting the floating crane and obtaining detailed parameters thereof according to basic lifting conditions of the floating crane; selecting a type of the main hook according to a weight of the quayside container crane full-unit, checking whether an interference between the boom of the floating crane and the front boom occurs, and determining an inclination angle of the floating crane during lifting; calculating a load on the lifting wire rope and selecting the lifting wire rope and a shackle; making preparations before lifting; and performing lifting at the dock.

The utility model discloses a container lifting appliance for a container ship. The container lifting appliance comprises a lifting appliance body, a guide frame and a driving mechanism, guide frames are installed on the front side, the rear side, the left end and the right end of the lifting tool body, each guide frame comprises a telescopic rod penetrating through the edge of the lifting tool body, one end of each telescopic rod is fixedly connected through a movable plate, a guide rod is fixed to the other end of each telescopic rod, and an inclined face is arranged at the lower end of each guide rod so as to make contact with a container in advance and guide the container in the descending process of the lifting tool. The driving mechanism comprises a motor fixed to the outer side of the lifting appliance body, an output shaft of the motor is connected with a lead screw, the lead screw penetrates through a threaded hole of the movable plate and is connected with a check block, and the motor drives the lead screw to rotate so as to drive the guide frame to conduct telescopic adjustment, so that the lifting appliance can be accurately in butt joint with the container in the shaking state. The lifting appliance butt joint error is reduced through the adjusting function of the guide frame, and the operation stability is improved.

The invention relates to the technical field of container hoisting, and particularly discloses a container crane for ports, which comprises a hoisting platform, lifting hooks are arranged at four corners of the bottom of the hoisting platform, the lifting hooks can move in the front-back and left-right directions, and two push plates capable of moving in the left-right direction and two L-shaped plates capable of moving up and down are arranged on one side of the hoisting platform. A first elastic piece is installed between the push plate and the lifting table, a second elastic piece capable of moving in the vertical direction is installed between the L-shaped plates and the lifting table, gears are installed on the opposite faces of the two L-shaped plates in the front-back direction, racks meshed with the gears are installed on the lifting table, and push assemblies used for pushing the gears to rotate are further installed on the L-shaped plates. The lifting platform has the beneficial effects that the situation that the lifting platform shakes in the lifting process can be avoided, positioning operation is conducted from one side of a container, lifting operation can be conducted under the condition that the containers are prevented from being dense, and fixing between the lifting hooks and the containers is rapidly completed.

The invention relates to the technical field of container wharf mechanical equipment, and discloses a container crane heightening device which is characterized in that two lower cross beams are arranged at the two ends of the bottom of a container crane, four walking trolleys are arranged at the four corners of the lower portions of the lower cross beams, and an anchoring mechanism is arranged below the middle position of each lower cross beam; the heightening device comprises four jacking devices, a plurality of flange jacking blocks and anchoring lengthening blocks, the jacking devices are arranged on the inner sides of the four walking trolleys below the lower cross beam, the four jacking devices jack the lower cross beam synchronously, the flange jacking blocks are fixed to the four walking trolleys and the lower cross beam, and the anchoring lengthening blocks are fixed to the flange jacking blocks. And an anchoring lengthening block is fixedly arranged on the anchoring mechanism. The invention further discloses a heightening method. According to the method, the cart part of the crane is heightened, the period is short, the cost is low, the construction safety is good, and the method is particularly suitable for occasions with the heightened height being 3 m or below.

The invention discloses a hoisting positioning remote control system and device for a port container crane, and relates to the technical field of cranes, the hoisting positioning remote control system comprises a remote control terminal, a network transmission unit, an equipment control unit, an offset detection unit, a monitoring and adjusting unit and a reason analysis unit. According to the invention, through sensor fusion detection and image auxiliary judgment of the offset detection unit, the accuracy of hanger position offset detection can be improved, offset detection is carried out before hoisting, during hoisting and after hoisting, and the positions, attitude data and video monitoring pictures of the hanger and the container can be checked in real time through the remote control terminal; position deviation of the lifting appliance is found in time, a remote control terminal sends an instruction to correct the deviation, the positioning precision of the lifting appliance is guaranteed, the lifting appliance can be rapidly and accurately aligned to a container, the grabbing effect on the container is guaranteed, stability is kept in the lifting process, and the situation that the container falls off due to gravity center deviation or shaking is avoided.

The utility model relates to the technical field of container cranes, in particular to a hoisting positioning device for a container crane, which is characterized in that a lifting appliance is mounted on the container crane in a liftable manner, a supporting bottom plate is mounted on the lifting appliance through a hoisting rope, limiting rods A are slidably connected to the left and right sides of the supporting bottom plate, and limiting rods B are slidably connected to the front and rear sides of the supporting bottom plate; according to the lifting appliance, lifting ropes are connected to four limiting rods A and limiting rods B, positioning frames are arranged on the container crane on the upper portion of the periphery of the lifting appliance in a sliding mode, a positioning telescopic frame is connected to the positioning frame at the bottommost in a sliding mode, a positioning rod is connected to the upper portion of the inner side of the positioning telescopic frame, and an upper suction cup is connected to the end of the positioning rod. A positioning mechanism A and a positioning mechanism B are mounted at the lower part of the inner side of the positioning telescopic frame and are used for supporting the limiting rod A and the limiting rod B, so that the hoisting process is safe and stable, and the use effect is good.

The invention relates to the technical field of remote control, in particular to a hoisting positioning remote control method and system for a port container crane, and the method comprises the following steps: collecting a space coordinate sequence of a lifting appliance, analyzing a vector included angle and a displacement length, generating a track curvature sequence, and generating risk points based on the comparison of curvature and space distance; the method comprises the following steps of: calculating the trajectory curvature and the spatial position of a lifting appliance, calculating the collision time advance, constructing a three-dimensional outer envelope surface based on a predicted value, calculating a stacking boundary error, performing projection calculation on a coverage proportion, and generating a lifting risk area. The lifting appliance movement is monitored in real time and potential risk points are identified by accurately calculating the trajectory curvature and the spatial position of the lifting appliance; the collision time is predicted by combining the ratio of the tangential speed to the spatial distance, the risk prediction precision is improved, three-dimensional pose analysis and error control enable the spatial error distribution of the lifting appliance to be finely managed, a risk area is calibrated in time, operation interruption is avoided, and the precision, safety and remote control capability of lifting operation are integrally improved.

The present invention relates to the technical field of intelligent manufacturing equipment industry, and more specifically to an intelligent scheduling method, system and storage medium for road-rail intermodal containers, including: obtaining historical environmental data of containers from a memory, preprocessing the historical environmental data, establishing a machine learning model, obtaining internal environmental data, calculating the length of time that materials in the container can be stored, prioritizing all containers, and arranging the stacking positions of containers in the road-rail intermodal logistics park yard based on the priority of the containers; selecting a genetic algorithm framework, creating a scheduling plan for the container, and taking different control measures for the container crane when the container crane executes the scheduling plan to prevent collisions between the container cranes. The present invention can complete the handling of the container before the materials in the container reach the critical conditions for storage.

The invention provides a container truck anti-hoisting method and system based on multi-line scanning, relates to the technical field of container cranes, and aims to avoid additional purchase of special equipment, reduce the number of hardware, simplify the system structure, reduce the debugging process and improve the production efficiency by utilizing an existing cart anti-collision laser scanner and an existing container truck guide laser scanner of a crane. The arrangement positions of existing cart anti-collision laser scanners and container truck guiding laser scanners are verified in use, the functions of the existing scanners are reasonably utilized by means of the existing scanners, interference risks cannot be additionally increased, and normal operation of anti-collision equipment, guiding equipment and the like of the crane is guaranteed; a fusion three-dimensional model is constructed by acquiring various information, and the states of the container truck, the lifting appliance and the surrounding environment can be comprehensively and accurately reflected; and when the container truck abnormally displaces and the speed of the lifting appliance exceeds the limit, an interlocking signal is triggered to stop, a reliable early warning mechanism is provided for preventing the container truck from being lifted, and the loading and unloading operation safety is effectively guaranteed.

A lubricating device for a pitching steel wire rope of a quayside container crane belongs to the technical field of steel wire rope lubrication and comprises a main body support, a lubricating sleeve capable of penetrating through a steel wire rope is arranged on the top side of the main body support, and an oil injection hole is formed in the lubricating sleeve; walking mechanisms arranged on the two sides of the lubricating sleeve are arranged at the two ends of the main body support correspondingly and can walk along the steel wire rope so as to drive the main body support to walk on the steel wire rope; an oil supply mechanism is arranged on the bottom side of the body support and connected with an oil conveying pipe, the oil conveying pipe is connected with an oil injection hole in the lubricating sleeve, and the oil supply mechanism can convey lubricating grease into an inner cavity of the lubricating sleeve through the oil conveying pipe and the oil injection hole. The lubricating device for the pitching steel wire rope of the quayside container crane is reasonable in design, simple in structure, convenient to use, good in lubricating effect, safe, reliable, capable of effectively improving working efficiency and reducing environmental pollution and suitable for popularization.

The invention discloses an electric energy feedback collection and load peak suppression system for a wharf crane, and relates to the technical field of wharf power supply and distribution and energy management. Wherein the wharf crane comprises a quayside container crane (quay crane), a rail or rubber-tyred container portal crane (gantry crane) and the like, which are called cranes for short hereinafter. According to the system, instantaneous power, average power, peak duration and power increasing rate of a wharf power station, feedback power and feedback electric energy of a crane, capacity and charging and discharging parameters of an energy storage device, and electric energy quality indexes of a power grid are collected in real time; respectively calculating a peak impact index, a feedback absorption coefficient, a peak valley switching coefficient and a harmonic suppression coefficient, and comparing and analyzing with a preset threshold to generate a corresponding strategy; and integrating the results of the modules, carrying out unified scheduling on the energy storage device, and realizing power fluctuation compensation and stable output through a smooth scheduling strategy, thereby constructing an operation mechanism. According to the method, the instantaneous peak power of the wharf power station can be effectively inhibited, the feedback energy consumption capability is improved, the peak-valley scheduling economy is optimized, the electric energy quality is improved, and the safety, stability and energy efficiency of system operation are improved.

The embodiment of the invention provides a hybrid power system of a quayside container crane and a control method, and relates to the technical field of hybrid power of quayside container cranes. The problems that due to the large power requirement of the quayside container crane, the power cannot be adapted when the hybrid power technology is applied, and the battery parallel connection risk is large are solved. The system comprises a DC bus, a bidirectional rectifier, a plurality of frequency converters, a plurality of charging and discharging branches and a control system. The plurality of charging and discharging branches are physically isolated and connected in parallel to the direct current bus, each charging and discharging branch comprises a battery pack and a bidirectional direct current converter, and the control system is used for calculating the distribution power of the single charging and discharging branch according to the real-time quay crane power requirement and the number of the online charging and discharging branches. The hybrid power control method for the quayside container crane is used for controlling the system, the distribution power of a single charging and discharging branch is accurately calculated through the real-time quayside crane power requirement and the number of online charging and discharging branches, and balanced charging and discharging between battery packs are achieved.

The present invention relates to the technical field of lithium battery replacement devices for container cranes, and discloses a lithium battery replacement device, including a lifting crane and a battery loading mechanism, wherein the battery loading mechanism is arranged on one side of the lifting crane, and one end of the lifting crane is fixedly connected to a suction lifting mechanism, and a linkage control mechanism is arranged on the lower side of the suction lifting mechanism, and a battery main body mechanism is fixedly connected to the lower side of the linkage control mechanism, and the battery main body mechanism is arranged inside the battery loading mechanism. In the present invention, the battery main body mechanism and the battery loading mechanism cooperate with each other, thereby alleviating the cumbersome disassembly and assembly operations and the inconvenience of replacement. Existing battery loading mechanisms mostly rely on bolts or simple clips for fixing, and the bolts are easy to loosen and the clips are easy to fail. Moreover, the suction lifting mechanism and the linkage control mechanism cooperate with each other, thereby improving the problems of time-consuming operation and high skill requirements for personnel when replacing lithium batteries, and difficulty in achieving rapid replacement.

The invention discloses a double-trolley shoreside bridge type container crane operation system, which is characterized in that two trolleys are arranged on a main beam of a crane, and the two trolleys respectively carry out container ship unloading and loading operation in different areas on a container ship in tandem in a step-by-step manner; and the two trolleys respectively implement ship loading and unloading operation inside and outside the gauge of the crane without mutual interference, and compared with a ship loading and unloading mode of a traditional main beam single trolley crane container, the ship loading and unloading operation efficiency of a container wharf is remarkably improved. According to the single-trolley crane, the two trolleys are arranged on the same main beam and the same track in tandem, the structure of an existing single-trolley crane can be directly transformed, new main beam and other structures do not need to be configured for newly-added trolleys, the single-trolley crane has the advantages of being simple in transformed structure and low in transformed cost, the loading and unloading efficiency is greatly improved, and meanwhile the loading and unloading cost is reduced. And the investment cost of the shoreside bridge crane is greatly reduced.

The utility model relates to a quayside container crane driver with a heat dissipation device, and belongs to the technical field of drivers. The crane driver comprises an electric control cabinet, a power supply control board, a driving control board and a power-off protector, the power supply control board and the driving control board are arranged on one side in the electric control cabinet, the two control boards are arranged in parallel, and a heat dissipation device is further arranged in the electric control cabinet. The heat dissipation device comprises a first mounting plate, a second mounting plate, a fixing plate and a heat dissipation fan, the fixing plate is connected with the first mounting plate and the second mounting plate, the heat dissipation fan is arranged on the fixing plate, the fixing plate is provided with a fixing through hole which penetrates through the end faces of the two sides and is used for mounting the heat dissipation fan, and an output port of the heat dissipation fan corresponds to the control panel. Through the heat dissipation device, heat accumulation in the electric control cabinet is relieved, and the probability that the two control panels are overheated and burnt is reduced.

This invention relates to the field of remote crane control technology, specifically a crane control device, comprising a cabinet, a support carrier, and a guardrail. The cabinet is mounted on the support carrier; the guardrail is also mounted on the support carrier; the support carrier is the crane's frame or trolley; a control mechanism is installed inside the cabinet, which receives control commands remotely sent from the control room; the control mechanism integrates the crane's electric hoist control unit, trolley control unit, and crane trolley control unit; it also includes: a detection mechanism installed inside the cabinet; and a protective mechanism installed inside the cabinet, used to detect if the cabinet becomes loose. This invention achieves remote control of port container cranes by controlling the movement of the trolley and crane units within the crane, as well as the movement of transported containers, through the control mechanism; and it eliminates the need for personnel to frequently climb the crane to maintain the cabinet, greatly improving the convenience of inspections.

This utility model discloses a container loading and unloading bridge weight sensor junction box, enabling wiring between the weight sensor and the electrical control box. The box includes a housing; a main control board with an intelligent main control module is installed inside the housing; a temperature sensor and a humidity sensor, controlled by the main control module, collect temperature and humidity data within the housing; and a wireless communication module controlled by the main control module. An external terminal with a display is installed outside the housing, communicating wirelessly with the main control module and receiving temperature and humidity data from the main control module, which is then displayed on the screen. In this utility model, because the temperature sensor and humidity sensor are installed inside the junction box to detect the internal temperature and humidity, and the external terminal with a display shows the internal temperature and humidity, the internal conditions of the housing can be understood without opening the box.

The embodiment of the invention provides a quayside container crane transfer platform, an impact resistance verification method thereof and a readable storage medium, and relates to quayside container crane transfer platforms. The problem that a quay crane transfer platform based on static elastic design is insufficient in high-energy instantaneous impact resistance and light weight can be solved. According to the verification method, the platform structure enters a controllable plastic deformation stage through finite element calculation. When the total strain energy T is larger than or equal to the impact potential energy E, it is indicated that the structure converts impact kinetic energy into internal energy of materials through deformation modes such as reinforcing rib buckling and panel plastic upheaval, and effective dissipation of the energy is completed. And when the maximum strain value epsilon is smaller than or equal to the limit strain epsilon max of the material, it is ensured that the plastic deformation of the bearing component is always within the ductility capacity range of the material. Impact energy is actively dissipated through structural deformation, and the platform can be lighter and the cost can be reduced in combination with a manufacturing process.

A container handling system, comprising a container crane configured to move a container between a container yard and a loading / unloading zone, the loading / unloading zone is configured to receive a transport vehicle for transporting the container. The loading / unloading zone further comprises a protective structure configured to cover a predetermined section of the loading / unloading zone.

The application provides a sling working condition detection method, a container crane and a port automation system. The method comprises the following steps: transforming a radar coordinate system into a target coordinate system, and calibrating the position of a sling center in the target coordinate system; obtaining radar information and calculating the edge position information of the sling in the current working condition according to the position of the sling center; calculating the relative position between the edge position of the sling and the to-be-lifted article according to the radar information and the edge position information, and judging whether the sling is in a safe working condition. The radar information obtained by the radar can be converted into a target coordinate system which is constructed according to the sling working environment, and the position information of the vehicle, the to-be-lifted article and the sling is identified. Whether the sling is in a safe working condition is judged by determining the relative position between the sling edge and the to-be-lifted article, so that the safety of the sling work is improved.

The invention discloses an active anti-swing and all-directional lifting appliance micro-motion system, relates to the technical field of cranes, solves the problems of efficiency loss and safety risk caused by lifting appliance swing of a traditional container crane, repeated correction cost of alignment deviation, adaptive fault of precision speed and automation requirements and the like, and comprises a crane carriage and a special lifting appliance, the hoisting trolley is connected with the winding system, the winding system comprises a plurality of steel wire ropes, the special lifting appliance comprises a lifting appliance upper frame and a plurality of steel wire rope fixing devices, the steel wire ropes are connected to the corresponding steel wire rope fixing devices, and corresponding moving devices are connected between the steel wire rope fixing devices and the lifting appliance upper frame. And the moving device drives the steel rope fixing device and the lifting appliance upper frame to move relatively. Through a winding system and a plurality of moving devices, a combined system of active anti-swing and omni-directional lifting appliance micro-motion is completed, and the dual effects of swing suppression and fine alignment are achieved.

The utility model relates to the technical field of transportation, in particular to an underground container logistics conveying module. Comprising a vehicle body used for transferring a container between a port and a freight station, and the vehicle body moves underground along a rail through a driving assembly; the positioning assembly is used for positioning the vehicle body and a lifting appliance of the container crane; the limiting assembly is used for limiting the movement of the container on the vehicle body; wherein a connector and a connecting groove which are matched with each other are arranged at the two ends of the vehicle body in the moving direction respectively, and a locking assembly used for preventing the connector from being separated from the connecting groove is arranged in the connecting groove. According to the utility model, the transfer efficiency is improved, the stable conveying of the container is ensured, the use flexibility is improved, and the application range is widened.

The invention provides a method for preventing a container from being scratched and a yard crane. According to the lifting appliance, under the working condition that the lifting appliance moves up and down when box grabbing and releasing operation is executed, the relative distance between the corner point pixel coordinates of the standard box at the target position and the edge of the adjacent box and the edge of the top face of the lock hole in different preset directions is calculated, and an alarm can be given under the condition that the relative distance is smaller than a threshold value; the function of preventing the container from being scratched when the lifting appliance moves up and down due to container grabbing and releasing is achieved, and then the technical effect that when the lifting appliance moves up and down during container grabbing and releasing operation, anti-collision early warning is conducted on the container, and therefore the working efficiency is improved is achieved. In this way, the technical problem that when the lifting appliance moves up and down during container grabbing and releasing operation, anti-collision early warning is difficult to conduct on the container is solved.

The application discloses a container front crane driving speed limit comprehensive control method and a crane. On the basis of cooperating with the speed limit control of an engine and a gearbox, a plurality of multi-dimensional reference signals for auxiliary speed limit control, such as a sling load, a large arm position, a hoisting box weight and the like, are provided by a sling controller, a large arm length angle sensor and a pressure sensor. Through the participation of the above-mentioned multi-element auxiliary signals, auxiliary speed limit can be carried out by detecting the load condition and the sling position, the safe height and the safe extension of the sling movement are indicated, and through the intuitive guidance prompt information, the driver can timely execute the correction operation, the visual obstruction or the large arm action overrun is avoided, and therefore the safety of the container crane driving and operation is improved. Further, in combination with the signal for detecting the container weight provided by the application, different levels of speed limit values can be set as required, the fine speed limit function is realized, the safety is ensured, and the crane operation efficiency can be improved.