45results about How to "Timely detection and treatment" patented technology

The invention provides a video signal monitoring method and a video signal monitoring system. The video signal monitoring method comprises the steps of respectively selecting a source video image and a target video image corresponding to each timestamp from a source video signal and a target video signal according to a plurality of appointed timestamps; respectively extracting source feature information and target feature information from the source video image and the target video image corresponding to each timestamp, and computing a reference feature difference value corresponding to each timestamp; according to the reference feature difference value of any timestamp, the reference feature difference value of previous n1 frames of any timestamp and the reference feature difference value of latter n2 frames of any timestamp, determining a target feature difference value corresponding to the any timestamp; comparing the target feature difference value corresponding to the any timestamp with a predetermined threshold to determine whether the target video image corresponding to the any timestamp is abnormal, and counting the quantity of the abnormal target video images; and giving an alarm for prompting when determining that the target video signal is abnormal according to the quantity of the abnormal target video images.

The invention relates to a real-time wireless monitoring apparatus for early-warning on integral overturn of a bridge. The real-time wireless monitoring apparatus comprises a box, a slide rheostat, a fixed protective resistor, a voltage measuring instrument with a signal transmission device, a power source, a beam side surface fixing plate, a main beam limiting plate and a displacing vertical rod; the box is fixed on a pier by use of a pier connecting bolt; the slide rheostat, the fixed protective resistor and the voltage measuring instrument with the signal transmission device are arranged in the box; the slide rheostat, the fixed protective resistor and the power source are connected in series to form a circuit; the voltage measuring instrument with the signal transmission device is connected to the two ends of the slide rheostat; the beam side surface fixing plate is fixed on a main beam by use of a beam side surface fixing bolt; the main beam limiting plate is bent and connected with the beam side surface fixing plate; one end of the displacing vertical rod is connected to the main beam limiting plate, while the other end of the displacing vertical rod is connected to the sliding end of the slide rheostat. Compared with the prior art, the real-time wireless monitoring apparatus is capable of sending out relative vertical displacement between the main beam of the bridge and a support by use of a wireless signal in real time.

The invention discloses an energy dynamic environment monitoring method, which is applied to the field of energy dynamic environment monitoring. Related operation data of electric equipment are collected through a sensor, the collected data are sent to a data gateway, and the data gateway receives and stores the related operation data of the electric equipment and then enables the related operation data to be sent to a central server. The central server receives and analyzes the related operation data of the electric equipment, gives warning to abnormal data according to analysis results, and prompts users to take corresponding measures. The energy dynamic environment monitoring method can find and process the abnormal data in time, completes real-time monitoring of energy environment of the electric equipment and is high in monitoring efficiency and small in workload of machine room management personnel.

The invention discloses a safety production early warning system and method. The system comprises a production equipment measurement module, a safety equipment monitoring module, a processing analysis module, an evaluation index module, a risk model database, an early warning information platform and a monitoring room. According to the scheme, the data and the image of the equipment during normal production are pre-stored in the risk model database, and the score of the equipment is preset according to the importance degree of the equipment, so that the real-time data and the image in actual safety production can be conveniently compared and analyzed, and the operation conditions of the production line and each piece of equipment can be timely judged; therefore, timely alarm and early warning of different degrees can be made, and a powerful guarantee is provided for safe production. Meanwhile, according to the scheme, the risk factors in the actual safety production process can be subjected to identification analysis, risk quantification and risk alarm prompting through the safety production early warning system, and in this way, type identification and grade quantification processing can be conducted on the actual risk factors.

The invention discloses a biological sample detection instrument convenient to adjust. The biological sample detection instrument comprises a probe three-dimensional rotation positioning mechanism anda base. The probe three-dimensional rotation positioning mechanism comprises three layers which are rotationally connected in an up-down manner. The upper layer comprises a main box body. The middlelayer is a hollow circular ring plate. The lower layer is a rectangular branch box body. The main box body is rotationally supported in an annular sliding rail on the hollow circular ring plate through a plurality of uniformly distributed pulleys arranged at the bottom of the main box body. The bottom of the hollow circular ring plate is fixedly connected with the rectangular branch box body. Therectangular branch box body is fixedly connected to the top wall of the base. A transverse plate is fixedly connected to the inner wall of the rectangular branch box body. An objective table is connected to the top wall of the transverse plate in a sliding manner. A through groove matched with the objective table is formed in the side wall of the rectangular branch box body. A biological sample detection head can be conveniently adjusted, so that detection data with the relatively high precision is convenient to obtain, operation is simple and convenient, the working efficiency of biological sample detection is effectively improved, and the maximum probe movement range is realized on the basis of small-sized sliding rail design; and compared with traditional design that a probe is rotatable on a three-dimensional positioning framework, the adjustable measurement range is greatly expanded.

The invention discloses a train obstacle detection and comprehensive early warning protection system. The system comprises a radio wave communication ranging device, a laser radar detection device, avisual detection and analysis device, a contact type obstacle and a derailing detection device. The radio wave communication ranging device, the laser radar detection device and the visual detection and analysis device are mounted on the head of a train, and the contact type obstacle and the derailing detection device are mounted at the bottom of the head of the train. The radio wave communicationranging device, the laser radar detection device, the visual detection and analysis device, the contact type obstacle and the derailing detection device send acquired or detected data to a system host, and the system host receives data and transmits the intelligently-analyzed data to a man-machine interaction terminal. According to the train early warning protection system, a multi-sensor communication detection measure in which a non-contact manner and a contact manner are combined is adopted, other trains, obstacles and people are detected in an omni-bearing manner from a far distance to aclose distance to contact, other manners can continue to be used for detection under the condition that one detection manner fails, and the operation safety of the train is guaranteed.

The invention relates to a method for intelligently scheduling multiple OCR engines, and the method comprises the following steps: calling an OCR application interface to upload a to-be-identified file, and assigning the type of the to-be-identified file; determining consumption types of OCR engines for processing the file according to the type of the file to be identified, creating an OCR queue corresponding to each consumption type of OCR engine, and setting at least one OCR engine of each consumption type; When the to-be-identified file requests to enter the OCR queue corresponding to the OCR engine, firstly executing overtime detection for judging whether the OCR engine of the consumption type is overtime or not, and if not, enabling the to-be-identified file to enter the correspondingOCR queue, overtime, incapability of enqueuing and informing a user. The method has the advantages that the advantages of the OCR recognition engines of all consumption types are fully utilized to achieve high-performance and high-accuracy recognition, all the OCR recognition engines are dispatched in order, and queue congestion, system errors and engine paralysis are prevented.

The invention provides an address resolution protocol attack processing method and device, the method comprises the steps: a network port corresponding to each virtual local area network in at least one virtual local area network is monitored, each virtual local area network comprises at least one virtual host; an ARP (address resolution protocol) data packet sent by each virtual host through the network port is acquired in real time, and an MAC (media access control) address, a source MAC address and a source IP address of a data link layer in the ARP data packet are extracted; according to the MAC address, the source MAC address and the source IP address of the data link layer and a mapping relation between a pre-saved MAC address of a data chain layer and a pre-saved IP address of a network layer of the virtual host, an ARP attack type is determined; and according to the determined ARP attack type and a mapping relation between the preset ARP attack type and a processing instruction, the processing instruction corresponding to the ARP attack type is determined and executed. According to the embodiment of the invention, the ARP attack of the virtual host can be monitored in real time and processed in time.

The invention relates to the technical field of databases, in particular to a database maintenance method and device. The method comprises the steps: acquiring the calling times and / or the calling time of the SQL statements used by the user in the database, acquiring the low-efficiency SQL statements according to the calling times and / or the calling time of the SQL statements, and then deleting the low-efficiency SQL statements or pushing the rewriting prompt information corresponding to the low-efficiency SQL statements to the user, so the low-efficiency statements can be found and processed in time, the operation efficiency of the database can be improved, and the operation and maintenance difficulty of the database can be greatly reduced due to the fact that technicians do not need to learn businesses borne by the database.

The invention discloses a high-precision mechanical arm used for industrial control. The high-precision mechanical arm comprises a control panel, a device main body, wheels, an oil filling hole, a bottom supporting plate, a telescopic pole, a pedestal, a steel rack, a working plate, a connecting plate, a connecting rod, a display screen, an emergency stop button, a gear, a slide wheel, a fixed clamping board, a mechanical rod, a slide wheel hole, anti-sliding teeth, a clamping surface and rear-row anti-sliding teeth, wherein the wheels are arranged at the lower end of the device main body; thecontrol panel is arranged at the upper end of the device main body; and the display screen is arranged at the left side of the upper end of the control panel. According to the high-precision mechanical arm used for the industrial control disclosed by the invention, the wheels are mounted on the bottom, so that the device can be conveniently moved to a working position; the whole device is connected by the connecting rod, and is controlled through hydraulic transmission; moreover, the display screen on the control panel can display various data in work, so that the emergency stop button can bepressed down for enabling the device to stop work when an emergency condition occurs, and therefore, problems can be timely found and processed while safety is guaranteed.

The invention discloses a subway track water detection alarm system. The subway track water detection alarm system comprises a monitoring server, a monitoring computer, a detection alarm host computer, multiple detection terminals, a printer and a sound-light alarm device, wherein the detection alarm host computer comprises a first MSP430 single-chip microcomputer, a first power supply cell, a data storage circuit module, a first CAN bus communication circuit module, an Ethernet communication circuit module, a first button operation circuit module, a liquid crystal display screen and a voice alarm circuit module, the detection terminal comprises a second MSP430 single-chip microcomputer, a second power supply cell, a second CAN bus communication circuit module, a second button operation circuit module, a clock circuit module, a signal conditioning circuit module and a water level sensor. The system has a simple circuit structure, is convenient to use and operate, realizes automatic detection on the subway track water and alarm, saves manpower and material resources, can timely discover the water and process the water and further has properties of high work reliability and strong practicality.

The invention relates to a downhole switch sliding sleeve installation machine and an installation operation process. The machine comprises a conveying frame, two conveying frame units, an assembly detection unit, a driving air cylinder, and a synchronous plate, wherein the two conveying frame units are installed on the middle part of the conveying frame, the assembly detection unit is installed at the left end of the conveying frame, the driving air cylinder is installed at the right end of the conveying frame, and the synchronous plate is installed at a protruding end of the driving air cylinder. The downhole switch sliding sleeve installation machine and the installation operation process can solve the problems that because an inner drum is tightly sleeved with an outer drum, in the process of manual sleeving operation, the sleeving operation can only be successfully completed after repeated sleeving; that if the drums are forcibly sleeved with each other, slight bending of the drumbodies may be caused, so the degree of smooth sliding between the inner drum and the outer drum is lowered and a defective product is thereby made; and that because no specific equipment is applied to the detection of the degree of smoothness, a defect cannot be timely discovered and disposed.

The invention discloses a movable container intelligent modular breeding pigsty which comprises a frame and a top cover. Two parallel open surfaces are arranged on the frame, and the top cover is arranged on one open surface of the frame; the other open face of the frame is used for being in contact with the ground. The pigsty further comprises an erecting plate and a fence, the erecting plate is arranged on the frame, and the erecting plate is parallel to the two open faces; the fence is arranged on the erecting plate, a plurality of independent spaces are defined by the fence on the erecting plate, and the space is a moving space for pigs; a collecting tank is arranged at one end of the erecting plate; the collecting tank is used for collecting and fermenting excreta of the pigs; the frame is provided with an air pipe; the air pipe is connected with a fan.

The invention discloses a medical insurance mobile settlement data interaction system. The system comprises a POS machine body, wherein the front face of the POS machine body is provided with a camera, a first display screen and a keyboard in sequence from top to bottom, a voice speaker is embedded in the left side of the camera, the position, at the right side of the first display screen, of thePOS machine body is provided with a card slot, the card slot is internally provided with a medical card, the inner portion of the POS machine body is provided with a face recognition module, a medicalcard reading module, a keyboard input module, a POS machine controller, a GPS positioning module, a display module, a voice broadcast module and a 4G network module separately, the POS machine controller is arranged in the center of the inner portion of the POS machine body, and the GPS positioning module, the keyboard input module and the 4G network module are arranged under the POS machine controller in sequence from left to right. By arranging the face recognition module, the GPS positioning module and the 4G network module, the medical insurance mobile settlement data interaction system solves the problem that mobile payment is hard in a traditional medical insurance settlement mode.

The invention provides a novel anti-thunder box which comprises a box cover and a box body. A remote signaling device is arranged in the box body and comprises an information receiving unit and a remote signaling output interface. A sound-light alarming device is connected with the information receiving unit. The sound-light alarming device comprises a converting module and a warning module. The converting module is connected with the information receiving unit. The warning module comprises a warning indicating lamp and a warning sound source. The warning indicating lamp is arranged on the box cover. The warning sound source is arranged on the back face of the box cover. An SPD module is arranged in the box body. A lightning stroke counting device comprises a lightning stroke counter module and a counting displaying module. An intelligent detecting module is placed in the box body and comprises a data collecting unit, a data processing unit and a data sending unit. A communication interface is arranged on the box body. Remote control over the anti-thunder box is achieved.

The invention discloses a conveniently adjustable biological sample detection instrument, which comprises a three-dimensional rotating positioning mechanism of a probe and a base. The three-dimensional rotating positioning mechanism of the probe comprises three layers connected by up and down rotation, the upper layer includes a main box, the middle layer is a hollow ring plate, and the lower layer It is a rectangular branch box, in which the main box is rotatably supported in the annular slide rail on the hollow ring plate by a plurality of evenly distributed pulleys at the bottom, and the bottom of the hollow ring plate is fixedly connected with the rectangular branch box. The rectangular branch box is fixedly connected to the top wall of the base, the inner wall of the rectangular branch box is fixedly connected with a horizontal plate, and the top wall of the horizontal plate is slidably connected with a loading platform, and the side wall of the rectangular branch box is excavated There is a through slot that matches the stage; the invention can conveniently adjust the biological sample detection head, thereby facilitating the acquisition of detection data with high accuracy, and is easy to operate, thereby effectively improving the working efficiency of biological sample detection. In addition, the maximum probe movement range is realized on the basis of the small-sized slide rail design, and compared with the traditional rotatable design of the probe on the three-dimensional positioning structure, this design greatly improves the adjustable measurement range .

The invention discloses a monitoring tool and method for an ironic service in an openstack environment, and relates to the technical field of openstacks. The monitoring tool is based on a telegraf assembly and a promelteus assembly, and further comprises an ironic input plug-in, an ironic processor plug-in and a promelteus output plug-in which are added in the telegraf assembly. The implementationprocess of the monitoring method based on the tool comprises the following steps of: periodically calling an ironic api through an ironic input plug-in added to a telegram component, so as to confirmthe availability of an ironic service and acquire the information of a basic node; processing information collected by an ironic input plug-in and generating a corresponding index through the ironicinput plug-in which is added to a telgraf component; outputting an index generated by an ironic probe sensor plug-in of a telegram component to a probe output plug-in according to the index of the telegram component; and the promelteus component pulls the index from the promelteus output plug-in of the telegram component and analyzes the index, and sends an alarm when an exception occurs. According to the invention, the state of the ironic service can be conveniently monitored, an alarm can be timely generated when an abnormality occurs, and the abnormality can be timely discovered and handledin a production environment, so that a major accident is avoided.

The invention discloses a chip function detection deviceof an intelligent card, which comprises a base and a mounting base, wherein a groove is welded in the base, a clamping block is movably connected to the interior of the groove, the mounting base is located on the left side of the clamping block, a sealing strip is fixedly connected to the interior of the mounting base, and an anti-skid pad isfixedly connected to the front end of the sealing strip. A first mounting disc is movably connected to the upper portion of the base, a sliding rod is horizontally mounted on the left side of the first mounting disc, a fixing column is welded to the left side of the sliding rod, a linear motor is movably connected to the lower portion of the sliding rod, a limiting block is horizontally mounted on the left side of the linear motor, and a fixing disc is movably connected to the lower portion of the linear motor. And a scanner is fixedly connected below the fixing disc. The chip function detection device of the intelligent card can detect the chip of the intelligent card, so that the working reliability of the chip of the intelligent card can be improved, and meanwhile, the chip function detection device is simple in structure and can be conveniently maintained by a user.

The invention discloses an intelligent alarm device based on an air conditioning system, belongs to the field of intelligent alarm, relates to an information interaction technology, and is used for solving the problem that the heating and refrigerating capacity of an existing air conditioning system changes or even becomes poor and has no self-feedback alarm. According to the preset temperature value, the initial temperature average value and the air conditioner type setting, the predicted working duration is obtained through calculation, the real-time temperature value is obtained through the temperature collecting module in real time in the refrigerating or heating process of the air conditioner system, and after the corresponding time is reached, the temperature average value of the current time is compared with the preset temperature value; if the difference value between the average temperature value at the current time and the preset temperature value T is within the error range, the air conditioning system is normal, and when the difference value between the average temperature value at the current time and the preset temperature value T is outside the error range, the air conditioning system is abnormal; the problem that the performance of the air conditioner becomes poor and is not easy to find is solved and can be found and processed in time.

The invention discloses a high-frequency shaking vibrator remote monitoring and control system on the basis of cloud technologies. The high-frequency shaking vibrator remote monitoring and control system on the basis of the cloud technologies comprises a high-frequency shaking vibrator, field bus, a PLC (programmable logic controller), a gateway, a cloud platform, a local server and a mobile terminal. The remote monitoring and control system has the advantages that high-frequency shaking vibration can be carried out on stock on nets by the high-frequency shaking vibrator, accordingly, fibers can be uniformly distributed, and distribution of transverse fibers can be reinforced; industrial field data can be timely uploaded to the cloud platform by the aid of the cloud technologies, and shared software and hardware resources and information can be provided to computers and other mobile terminals according to requirements by the aid of the cloud technologies; remote visualization can be implemented, effects of timely monitoring and controlling the high-frequency shaking vibrator during work can be realized, the work performance of the high-frequency shaking vibrator can be guaranteed,and the quality of paper can be improved.

The invention provides a method for disk management and a system for the disk management. The method for the disk management includes the following steps: reserving a backup section in every subarea of a disk; orderly scanning every subarea in the disk, and judging if a bad track is existed in every subarea; if it is, marking the bad track and remapping to the backup section in the subarea where the bad track locates or the backup section in the subarea with the closest distance to the subarea where the bad track locates; recording the relationship of the remapping. Through distributing the backup section of the disk to every disk subarea, the mean track seeking distance is shortened, and further the track seeking time is reduced; the method and the system for the disk management can timely find out and handle the bad track of the disk, prolong the service life of the disk, and are good for ensuring the data safety.

The invention relates to a real-time wireless monitoring apparatus for early-warning on integral overturn of a bridge. The real-time wireless monitoring apparatus comprises a box, a slide rheostat, a fixed protective resistor, a voltage measuring instrument with a signal transmission device, a power source, a beam side surface fixing plate, a main beam limiting plate and a displacing vertical rod; the box is fixed on a pier by use of a pier connecting bolt; the slide rheostat, the fixed protective resistor and the voltage measuring instrument with the signal transmission device are arranged in the box; the slide rheostat, the fixed protective resistor and the power source are connected in series to form a circuit; the voltage measuring instrument with the signal transmission device is connected to the two ends of the slide rheostat; the beam side surface fixing plate is fixed on a main beam by use of a beam side surface fixing bolt; the main beam limiting plate is bent and connected with the beam side surface fixing plate; one end of the displacing vertical rod is connected to the main beam limiting plate, while the other end of the displacing vertical rod is connected to the sliding end of the slide rheostat. Compared with the prior art, the real-time wireless monitoring apparatus is capable of sending out relative vertical displacement between the main beam of the bridge and a support by use of a wireless signal in real time.

The invention belongs to the technical field of computer room management, and discloses a data center classification early warning method, which includes: constructing a risk event database; crawling risk event information; Obtain the risk level of the associated risk event according to the risk event database; obtain the feature value of the associated risk event according to the risk level of the associated risk event; obtain the warning level corresponding to the feature value according to the risk event database ; Send early warning information to the associated user of the associated risk event according to the warning level. The invention also discloses an electronic device and a computer-readable storage medium. The invention comprehensively monitors the risk events by crawling the risk event information, and warns the user by setting the risk level and the early warning level, so that the warning notification personnel are pertinent and the accuracy of the risk event early warning is improved.

The invention discloses a linear cutting machine tool for automobile part production and a using method thereof. The linear cutting machine tool comprises a machine base, a working table and a working groove, the working table is installed at the upper end of the machine base, the working groove is formed in the upper end of the working table, and insulating cooling liquid is contained in the working groove. The wire cutting machine tool has the beneficial effects that through the design of adjusting grooves, clamping plates and limiting bolts, the wire cutting machine tool can have a rapid adjusting function, when a metal wire shakes, the adjusting time can be greatly shortened when a worker adjusts the tightness of the metal wire, and therefore the working efficiency of the worker is improved; and through the design of a liquid level sensor and an alarm, the linear cutting machine tool can have a cooling medium alarm function, in the use process of the machine tool, a cooling medium is influenced by high temperature to generate a volatilization effect, and when the cooling medium is less and reaches a set threshold value, alarm information can be sent out, so that the worker can find and process in time, and the use safety of the machine tool is improved.

The invention discloses a convenient-to-adjust biological sample detection instrument. The convenient-to-adjust biological sample detection instrument comprises a probe three-dimensional rotary positioning mechanism and a base; the probe three-dimensional rotary positioning mechanism comprises three layers which are rotatably connected along a vertical direction, wherein the upper layer comprises a main box body, the middle layer is a hollow annular plate, and the lower layer is a rectangular branch box body; the main box body is rotationally supported in an annular sliding rail on the hollow annular plate through a plurality of uniformly distributed sliding wheels arranged at the bottom of the main box body; the bottom of the hollow annular plate is in fixed abut joint with with the rectangular branch box body; the rectangular branch box body is fixedly connected to the top wall of the base; a transverse plate is fixedly connected to the inner wall of the rectangular branch box body; an objective table is slidably connected to the top wall of the transverse plate; and a through groove matched with the objective table is dug in the side wall of the rectangular branch box body. According to the convenient-to-adjust biological sample detection instrument of the invention, a biological sample detection head can be conveniently adjusted, detection data with relatively high precision can be conveniently obtained, the operation is simple and convenient, and the working efficiency of biological sample detection is effectively improved; in addition, the maximized probe moving range is realized on the basis of the design of the small-size slide rail; and compared with the rotatable design of a traditional probe on a three-dimensional classification positioning framework, the Convenient-to-adjust biological sample detection instrument can greatly extend an adjustable measurement range.

The invention discloses a bidding amount cleaning method for a bidding announcement, and aims to solve the technical problem of inaccurate bidding amount obtained at present. The method comprises thefollowing steps: (1) data format conversion; (2) acquiring the industrial and commercial registration capital of the bid winning unit; (3) obtaining bid winning prices of historical bid winning itemsof the bid winning unit; and (4) verifying and cleaning according to the industrial and commercial registration capital and the bid winning prices of the historical bid winning items of the bid winning unit. The method has the beneficial technical effects of accurate data acquisition, high execution efficiency, high automation degree and reduction of manual work intensity.

The invention discloses a skeleton cable. The skeleton cable comprises a reinforcing piece, a skeleton, a waterproof sealing layer and an outer sheath which are sequentially arranged from inside to outside, a conductive unit is installed in a skeleton groove of the skeleton, and an installation groove is formed in the outer sheath. The skeleton cable further comprises: a flexible heat-conducting plate, wherein one end of the flexible heat-conducting plate is positioned in the skeleton groove, and the other end of the flexible heat-conducting plate penetrates through the waterproof sealing layer and the outer sheath and then enters the corresponding mounting groove; a thermoelectric power generation piece arranged in the mounting groove, wherein the hot end of the thermoelectric power generation piece is attached to and matched with a heat conduction part; a cooling fin arranged in the mounting groove and attached to and matched with the cold end of the thermoelectric power generation piece; a controller comprising a battery module and a communication module; and a temperature sensor arranged on the heat conduction part. The skeleton cable can generate electricity by itself through the temperature difference power generation structure, the temperature of the flexible heat- conducting plate can be detected through the temperature sensor, so that the temperature of a conductive unit in the skeleton groove is obtained, a signal can be transmitted to a server in time through the communication module of the controller, and a worker can find and process in time.

The invention discloses an automatic drain valve sewage discharge system which comprises a condensate water collecting tank and further comprises a self-turning plate water level sensor connected intothe condensate water collecting tank. A still kettle flange butt joint hole is formed in the upper end of the condensate water collecting tank and communicates with a condensate water flow stabilizing device in the condensate water collecting tank. An exhaust hole is formed in the bottom of the condensate water collecting tank and provided with a manual ball valve. Whether for the problem that cost is increased due to an obsolete coal boiler or steam from a power plant or in terms of energy conservation, emission reduction and environment protection, the PLC full-automatic drain and sewage discharge system of a still kettle has great practical significance.