224 results about "Lower limit" patented technology

Provided is an image forming apparatus including: an image forming unit configured to form an image on a recording material; an exhaust fan configured to exhaust air inside the image forming apparatus; a CPU configured to control rotation of the exhaust fan; and a memory configured to store in advance a first control setting value for rotating the exhaust fan at a first target rotation speed. The CPU rotates the exhaust fan based on the first control setting value, and permits the image forming unit to form an image when a rotation speed of the exhaust fan becomes equal to or faster than a lower limit rotation speed for suppressing a discharge amount of UFPs. When a predetermined time period has elapsed, the CPU performs feedback control for the exhaust fan such that the exhaust fan is rotated faster than the first target rotation speed.

The invention provides a data exception early warning method and device based on a dynamic threshold model. The method comprises the following steps: firstly, constructing an index time sequence library and an event library for storing index and event information; fusing the historical same-period base line, the trend term and the event influence value and generating a base line through a dynamic weight formula; calculating upper and lower limits of a dynamic threshold by combining the fluctuation acceleration and a basic fluctuation coefficient; and finally, comparing the real-time index value with a threshold range to judge whether to give an alarm, and optimizing the model or updating the event library according to a manual labeling result. According to the method, dynamic and accurate early warning of data exception can be realized, service scene changes can be adapted, the early warning accuracy is continuously improved through feedback optimization, and powerful support is provided for stable service operation and efficient exception disposal.

The invention discloses an intelligent online monitoring method and system for a transformer, and the method comprises the steps: dividing historical data into a plurality of working condition intervals according to the historical working condition data, and enabling each working condition interval to have a numerical range corresponding to a working condition parameter; based on all historical operation data in the working condition interval, a dynamic reference range corresponding to the working condition interval is determined, and the dynamic reference range is a numerical value interval with an upper limit value and a lower limit value; obtaining a current operation parameter value and a corresponding current working condition parameter value of the target transformer in real time; determining a target working condition interval from the plurality of working condition intervals according to the current working condition parameter value; obtaining a target dynamic reference range corresponding to the target working condition interval; and when it is determined that the current operation parameter value is not located in the target dynamic reference range, it is determined that the transformer is abnormal, and an early warning signal is generated. The method is used for improving the early warning accuracy and reliability of transformer monitoring.

The invention relates to the technical field of FPC (Flexible Printed Circuit) laminated structure optimization, in particular to a module FPC laminated structure optimization system based on signal integrity, which comprises a laminated parameter sensitivity extraction module used for defining the thickness of a dielectric layer, the thickness of a copper foil and a dielectric constant as closed interval values with upper and lower boundaries according to FPC design specifications. According to the method, the accumulated deviation area and the normalized confidence score are obtained in combination with integral operation, conversion from a frequency domain to a time domain and from qualitative analysis to quantitative evaluation is achieved, tiny flaws of impedance continuity are captured, inferior paths are screened based on the confidence score, and a physical junction area is positioned. The geometric gravity center of the deviation area is calculated to be matched with the slope and the length of the gradient line, a smoothly-transited geometric figure is constructed, structural compensation can be achieved in areas where impedance is prone to sudden change such as a reinforcing plate junction and covering film pressing, and signal reflection caused by physical sudden change of a stacked structure is eliminated.

The invention discloses a reaction steam turbine through-flow method and system based on variable reaction degree optimization, and belongs to the technical field of steam turbine through-flow design. The method comprises the steps that an initial geometric model of a steam turbine through-flow part and thermal boundary conditions of all stages are obtained; inputting the initial geometric model and the thermal boundary conditions into a flow field solver, and solving a flow control equation to obtain an original flow field solution; constructing a functional taking through-flow efficiency as a target, and deducing an adjoint equation corresponding to the flow control equation; solving the adjoint equation to obtain gradient information of the target functional to each level of reaction degree; inputting the gradient information into a sequential quadratic programming optimizer, and iteratively updating the reactance of each stage by combining the maximum equivalent stress upper limit of the moving blade and the lower limit of the through-flow throat area to generate a variable reactance distribution scheme; and adjusting molded line geometric parameters of each stage of stationary blade and moving blade, and outputting optimized three-dimensional molded line data and a digital model file for numerical control machining. According to the method, the in-stage flow loss is reduced, and the design robustness is enhanced.

The invention discloses a distributed current limiting method, device and system and a storage medium. The method comprises the following steps: periodically generating and broadcasting a concurrent suggestion interval based on a local operation state; concurrence suggestion intervals generated by the service instance and from other service instances are received, intersection operation is carried out, a global feasible interval is obtained, the upper limit is the minimum value of the upper limits of all the concurrence suggestion intervals, and the lower limit is the maximum value of the lower limits of all the concurrence suggestion intervals; and determining a local current limiting threshold based on the global feasible interval and the local dynamic weight. Each service instance receives the concurrence suggestion interval and then performs intersection operation to determine the global feasible interval, so that the upper limit is monotonically not increased and cannot be exceeded, the security invariant constraint chain is obtained, a central coordinator or a global synchronous clock is not needed, and the global concurrence quantity does not exceed the security upper limit under any network condition; and determining a local current-limiting threshold value based on the global feasible interval and the local dynamic weight, and realizing refined and adaptive current-limiting management.

A heater power configuration method based on dual-objective collaborative optimization belongs to a heating optimization technology, and is characterized by comprising the following steps: firstly, establishing a three-dimensional geometric model of a heater; then performing grid division on the three-dimensional model, defining material attributes of each part and setting reasonable boundary conditions; determining a target temperature and a temperature uniformity index; constructing an optimization model which takes the target temperature as an optimization target function and takes the temperature uniformity as a constraint condition; determining an initial value range of the power density of the heater by using a parameterized scanning function; calling a parameter optimization module in the multi-physics field coupling simulation software, and carrying out iterative optimization on the power density parameter; after optimization calculation is completed, whether temperature uniformity meets set requirements or not is judged, if not, the upper limit and the lower limit of the power density are adjusted in combination with a simulation result, optimization is conducted again, and finally the optimal power parameter is output. Accurate configuration of the power of the heater is achieved, and the uniformity of a temperature field and the energy efficiency of the system are remarkably improved.

The invention belongs to an SDTW-IPAM-based short-term power load prediction method and system, electronic equipment and a storage medium. The method comprises the steps of data preprocessing, clustering analysis, single-class prediction model construction and future load prediction. The clustering analysis comprises setting of upper and lower limits of a cluster number, construction of a distance matrix, calculation of a Gap value and a standard error, selection of an optimal cluster number, generation of an initial center, clustering processing and normalization processing; according to the method, a distance measurement method is introduced into load clustering, so that the dynamic time sequence characteristics of a load curve can be described more accurately, the local time deformation of the load curve can be effectively identified, and the distinguishing capability of similar load days under the influence of weather, events or potential new energy fluctuation is improved; a clustering algorithm is improved by using statistics and an initialization strategy, so that the stability and the accuracy of performing mode recognition on complex load data are improved, and the load can be effectively divided into typical modes with different dynamic characteristics.

The invention discloses a refrigeration control method based on inverter compressor control, which relates to the technical field of refrigeration equipment control, and comprises the following steps: acquiring operation data of a refrigeration system according to a preset period, and extracting a thermal response characteristic representing a cooling rate attenuation acceleration by performing differential processing on an indoor temperature; and calculating a thermal rebound sensitivity characteristic by combining the frequency change gradient. A thermal inertia potential energy index representing the heat storage load of the enclosure structure is generated through time domain accumulation processing, a nonlinear drift modulation model is constructed accordingly, and a virtual set temperature and a dynamic frequency lower limit value are generated. And finally calculating a basic adjusting frequency based on the virtual set temperature, and selecting the maximum value of the basic adjusting frequency and the lower limit value of the dynamic frequency as a target driving frequency. Through cooperation of algorithm soft traction and physical hard lifting, the problem of overshoot oscillation in a complex thermal environment is solved, and temperature control stability and energy saving performance are improved.

The application relates to the field of photoetching technology, and particularly relates to a method and device for rapidly screening overlay mark manufacturability and computer equipment, which comprises the following steps: inputting preset range of process window conditions, selecting upper limit value and lower limit value as extreme process window conditions; calculating initial process variation bandwidth value based on the extreme process window conditions, and performing first screening on the initial process variation bandwidth value based on a preset screening ratio; calculating to-be-processed process window values corresponding to the screened process variation bandwidth values; performing second screening on the to-be-processed process window values based on a preset standard range to obtain final process window values; and screening the overlay marks corresponding to the final process window values. The application further provides a device and computer equipment. The problems of time and labor consumption in screening overlay mark manufacturability are solved.

The application discloses a method for determining the quality proportion of each grade based on the maximum utilization rate of cement gobi material, and belongs to the technical field of cement stabilized base. Firstly, the aggregate with a particle size greater than the maximum screen hole of a target grading is removed from the original gobi material, and the passing rate is normalized. According to the particle size from small to large, when the normalized passing rate B a of the first determined screen hole p a is not within the range of the set upper limit and the set lower limit of the passing rate, the first grade is set. The passing rate of each screen hole is corrected. According to the particle size from small to large, when the once corrected passing rate B b of the first determined screen hole p b修正1 is not within the range of the set upper limit and the set lower limit of the passing rate, the second grade is set. The passing rate of each screen hole is corrected. The grading is continued or stopped. The quality proportion of each grade is determined. The application can quickly determine the grading screen hole size with the maximum utilization rate of gobi material and the quality proportion of each grade under the condition that the specification requirements of the mixture grading are met.

The embodiment of the invention discloses an electric leakage detection method, device and equipment, a medium and a program product. Comprising the steps of obtaining a to-be-processed signal in an electric leakage judgment period; according to the to-be-processed signal, waveform peak points in the electric leakage determination period and peak left edge points corresponding to the waveform peak points are determined; determining every two adjacent peak left edge points as a peak left edge point group, and counting the total sampling number and the trough sampling number corresponding to each peak left edge point group; according to each total sampling number, each trough sampling number, a preset correction wave period sampling number lower limit value, a preset correction wave period sampling number upper limit value and a preset trough sampling number threshold value, determining a leakage waveform from correction waveforms corresponding to each peak left edge point group; and determining an electric leakage detection result according to the distribution condition of each electric leakage waveform in the electric leakage judgment period. The complexity and the data operand of a circuit required by electric leakage detection are reduced, and the stability and the universality of electric leakage detection are improved.

The invention belongs to a price determination method, and provides a method for determining upper and lower limits of contract price fluctuation of a power market and a related device, aiming at the technical problems that a price limit mechanism for setting fixed upper and lower limits of prices is adopted in the current power transaction, a price discovery suppression function exists, and violent price swing within a day cannot be effectively coped with. Calculating a positive excess sample and / or a negative excess sample, then taking the positive excess sample and / or the negative excess sample as input, and obtaining a morphological parameter and a scale parameter when a log-likelihood value of the positive excess sample and / or a log-likelihood value of the negative excess sample converges through generalized Pareto distribution iterative calculation; and finally, positive tail risk measurement index expected loss and / or negative tail risk measurement index expected loss are / is obtained through calculation and serve as an upper limit and a lower limit of contract price fluctuation of the electricity market. And the technical problem of violent price swing within the day can be effectively solved.

The disclosed vehicle control device (10) is provided with: a sum model (M1) in which the motion states of a left drive system and a right drive system during straight movement are modeled; a difference model (M2) in which the motion states of the left drive system and the right drive system during turning are modeled; a calculation unit (11); a restriction unit (12); a calculation unit (11) calculates a sum mode target slip rate (yS) and a difference mode target slip rate (yD). A restriction unit (12) sets upper limit values (ySH, yDH) and lower limit values (ySL, yDL) for the sum-mode target slip ratio (yS) and the difference-mode target slip ratio (yD), respectively, and restricts the target slip ratios (yS, yD). The control unit (13) controls the respective driving forces of the left drive system and the right drive system on the basis of the sum mode target slip rate (yS) and the difference mode target slip rate (yD) that have been limited, the sum model (M1), and the difference model (M2).

A proximity deciding device includes: a capacitive sensor electrode covered with a cover having a manipulation surface; a measurement circuit that measures capacitance between the capacitive sensor electrode and an indicating body; a proximity deciding unit that makes a decision as to whether a proximity state is in progress according to a difference obtained by subtracting a reference value from the capacitance; and a correcting unit that corrects the reference value. The correcting unit stores, in a storage unit, a lower limit, for accumulated inputs, based on the reference value before the proximity state; calculates, in the proximity state, a cumulative value for a change of the capacitance; updates the reference value according to a cumulative input value (cumulative value or lower limit); and sets the cumulative input value to the cumulative value or lower limit according to whether the cumulative value is larger or smaller than the lower limit.

The application discloses a code rate control method for inhibiting super-large I frame. According to the coding state of a current video sequence, the upper limit value of the coding bit number of the I frame which will not cause code rate control abnormality is calculated. According to the actual coding bit number, the quantization parameter and the intra-frame coding complexity of the previous coded I frame, in combination with the upper limit value of the coding bit number and the intra-frame coding complexity of the to-be-coded I frame, the lower limit value of the quantization parameter of the to-be-coded I frame is calculated. According to the quantization parameter of the previous coded P frame or B frame, the quantization parameter of the to-be-coded I frame which has inhibiting effect on the breathing effect is calculated. The larger value of the lower limit value of the quantization parameter of the to-be-coded I frame and the quantization parameter of the to-be-coded I frame which has inhibiting effect on the breathing effect is selected as the quantization parameter of the to-be-coded I frame, which is used in the actual coding process of the to-be-coded I frame. The application takes the video frame level quantization parameter as the operation core of the code rate control algorithm, which is more suitable for hardware implementation.

This invention belongs to the technical field of precision roll-to-roll manufacturing, specifically relating to a multi-level control method for the lateral sway of an ultrathin film in a roll-to-roll system. The method includes: setting up multi-level lateral correction units arranged sequentially along the running direction of the ultrathin film strip on the roll-to-roll system; real-time acquisition of lateral sway data at each level; and executing multi-level control of the ultrathin film lateral sway. The structure and control parameters of the fine-tuning correction unit satisfy the following: correcting the lateral position of the strip relative to the target position with a preset small stroke amplitude sway component; the structure and control parameters of the coarse-tuning correction unit satisfy the following: correcting the lateral position of the strip relative to the target position with a preset large stroke amplitude sway component; the lower limit of the small stroke amplitude is less than the target processing range, and the upper limit of the small stroke amplitude is greater than the lower limit of the large stroke amplitude. This invention can improve the processing accuracy of the processing area in the roll-to-roll manufacturing system, ensuring the overall stability of the system and the quality of the finished product.

The application provides a power control method and device, electronic equipment and a storage medium, wherein the method comprises: in the case of determining that a target motor is in normal operation, obtaining a target running speed of the target motor; determining a target interval in which the target running speed is located, obtaining an upper limit value and a lower limit value of the target interval; comparing the upper limit value of the target interval with the lower limit value of the target interval to obtain a first comparison result, and comparing the upper limit value of the target interval with an upper limit value of a reference interval to obtain a second comparison result, wherein the reference interval is another set interval except the target interval, and the lower limit value of the target interval is greater than or equal to the upper limit value of the reference interval; and adjusting the running power of the target motor according to the first comparison result and the second comparison result. Through the application, the problem that the motor performance cannot be maintained at a high performance condition when the motor is controlled at a constant power in the related art is solved.

The invention relates to an annealing optimization algorithm during impeller parameter sensitivity analysis and response surface mismatch. The algorithm specifically comprises the following steps: 1) analyzing the sensitivity of impeller parameter change to compressor performance change; 2) analyzing the construction reliability of the impeller optimization response surface; 3) an annealing algorithm optimization method of impeller parameters; s11, determining geometric characteristic parameters of the centrifugal compressor impeller to be optimized, and constructing a parameterized model; s12, determining output parameters of the optimized impeller; s13, determining the upper and lower limits of the optimization process of the geometric characteristic parameters of the centrifugal compressor impeller to be optimized; s14, constructing a sensitivity analysis test sample, and adopting Box-Behnken design to construct the sensitivity analysis test sample; and S15, impeller parameter sensitivity analysis. And S16, establishing an upper and lower limit interval different from the traditional input variable in S13. On the premise that professional knowledge needs in the impeller design and optimization process are not increased as much as possible, the method for extracting effective design variables, avoiding blind optimization, improving calculation efficiency and improving optimization logic reliability is provided.

The application discloses a kind of distributed current limiting method, device, system and storage medium, including periodically generating and broadcasting concurrent suggestion interval based on local running state;Receive concurrent suggestion interval generated by itself and from other service instances and carry out intersection operation, obtain global feasible interval, upper limit is the minimum value of the upper limit of all concurrent suggestion intervals, lower limit is the maximum value of the lower limit of all concurrent suggestion intervals;Determine local current limiting threshold based on global feasible interval and local dynamic weight.The intersection operation is carried out after each service instance of the application receives concurrent suggestion interval to determine global feasible interval, ensure that upper limit is monotonically not increased and upper limit cannot be exceeded, obtain safe invariant constraint chain, without central coordinator or global synchronous clock, in any network condition, guarantee that global concurrency is not more than safe upper limit, determine local current limiting threshold based on global feasible interval and local dynamic weight, realize fine, adaptive current limiting management.

The present invention aims at improving the convenience of parking assistance. A control device (111) of a driving assistance device (200) of the present invention controls an emergency brake device for causing an emergency brake operation based on a distance to an obstacle detected by a sonar (3) constituting a detection device mounted on a vehicle (1), and a parking assistance device for performing parking assistance of the vehicle (1). The sonar (3) constituting the detection device is predetermined with an upper limit value and a lower limit value for defining a range of the above-mentioned distance capable of detecting the obstacle. In a case where the above-mentioned distance between the vehicle (1) and the obstacle at a target position, i.e., a target parking position, where the vehicle (1) is caused to stop in the parking assistance is less than the lower limit value, the control device (111) invalidates the operation of the emergency brake device.

The utility model relates to the technical field of PXIE machine cases, and discloses a transversely-arranged PXIE machine case which comprises a case body, a control base is fixedly connected to the left side in the case body, an upper limiting plate is fixedly connected to the upper side in the case body, two sets of upper cooling fans are fixedly connected to the top end in the case body, and two sets of lower cooling fans are fixedly connected to the top end in the case body. Two groups of lower cooling fans are fixedly connected to the bottom end of the interior of the box body, a first ventilation opening is formed in the top end of the box body, a second ventilation opening is formed in the bottom end of the box body, and a slidable convenient-to-mount structure is arranged in the box body. Hardware is placed at the corresponding position of the lower limiting plate, after the hardware is fixedly connected with the lower limiting plate, the multiple sets of pulleys are arranged at the bottom end of the lower limiting plate, the two sets of sliding rails are fixedly connected to the bottom end in the box body, the multiple sets of pulleys are matched with the sliding rails in size, the pulleys move front and back on the corresponding sliding rails, and therefore rapid installation of the hardware is achieved.

The present application relates to a kind of cabin interior arrangement control method for the protection of pedestrian, comprising obtaining fine CAS structure of styling surface;Pedestrian protection test area is obtained;Target decomposition, make the score plan of row protection, determine the lower limit value of score according to development target, then according to the decomposition score of different vehicle, the score is decomposed into head type score and leg type score, and score chromatogram is drafted;Output limiting surface, according to the distribution state of score chromatogram, while cooperating with the mapping relationship between cabin interior space and score, the upper limit of the limiting surface of head type and leg type area is obtained, and the upper limit limiting surface is output;Cabin interior arrangement is completed using limiting surface.The present application is a kind of cabin interior arrangement control method for the protection of pedestrian, for guiding cabin interior arrangement;Vehicle cabin interior arrangement can be completed by using this method and meet the requirements of pedestrian protection, compared with traditional cabin interior arrangement mode, this method does not need to repeat and, greatly shorten the development cycle of pedestrian protection performance, improve the development efficiency of pedestrian protection.

Embodiments of the present disclosure provide a solution for video processing. A method for video processing is proposed. The method comprises: for a conversion between a current video block of a video and a bitstream of the video, limiting values of first samples associated with the current video block by using a clipping operation, at least one parameter of the clipping operation is indicated in the bitstream, and the at least one parameter comprises at least one of an upper limit value or a lower limit value; and performing the conversion based on the limited values.

The invention relates to the technical field of aircraft structure fatigue tests, and discloses an aircraft test loading lever non-collinear connecting device and a design method thereof.A connecting joint is designed to be of a structure with a U-shaped cross section, so that a dowel bar can be vertically inserted into a force transmission hole of a force transmission single lug; therefore, a force transmission path between a lever connection point and an airplane test loading point is changed, test force load application in a narrow space is realized, and the device has the characteristics of simple structural form, reliable connection mode, convenience in installation and the like; in the design process of the loading lever of the non-collinear connecting device, the lower limit value of the diameter of a dowel bar, the lower limit value of the diameter of a bolt hole and the minimum distance from the center of the bolt hole to the edge of a U-shaped supporting plate are analyzed in advance, and then the structural design of the loading lever, a force transmission single lug and a connecting joint is conducted according to the key parameters. The aircraft test loading lever non-collinear connecting device which is reasonable in structure and excellent in performance can be designed, and the requirement of an aircraft structure fatigue test is met.

The invention discloses an optimal design method and system for an injection mold, and relates to the technical field of injection mold optimizing.By constructing a cooling time statistical model of a qualified forming period, aggregation statistics is conducted on cooling lag time of all mold cavities and point locations in qualified samples, representative cooling time length distribution is established, and the optimal design of the injection mold is achieved. And a data basis is provided for cooling control. Through the output value of the cooling window function, the cooling process can be divided into a reasonable interval and an unreasonable interval, and traceable labels are formed in data recording and quality tracing. Meanwhile, in combination with the deviation degree of the upper bound and the lower bound, a cooling abnormal degree grading mechanism can be extended, and support is provided for intelligent adjustment strategy selection. An abnormal cooling lag point is identified through the effective cooling attenuation stage starting point Teff; through the normalized WS data, the abnormal deviation trend point of the temperature recovery curve can be visually found, and an accurate cooling deviation input basis is provided for a subsequent module, so that differential cooling control suggestions are supported.

The invention provides an encryption and decryption performance evaluation method and device, equipment and a medium, and the method comprises the steps: receiving an encryption and decryption performance test instruction, carrying out multiple times of encryption and decryption tests according to a length parameter and a target throughput range through employing an encryption and decryption algorithm corresponding to an encryption and decryption algorithm type, and carrying out the evaluation of the encryption and decryption performance according to the packet loss condition in each encryption and decryption test process; the upper bound or the lower bound of the target throughput range is adjusted until the deviation between the upper bound and the lower bound of the adjusted target throughput range is smaller than or equal to a preset deviation, the adjusted target throughput range is smaller than the target throughput range before adjustment, and test data in the multiple encryption and decryption test processes are obtained, the encryption and decryption performance evaluation result is determined according to the test data, the throughput range is adjusted through iteration, the throughput difference value can quickly approach the encryption and decryption performance critical point, and therefore the test frequency is remarkably reduced, and the encryption and decryption performance test efficiency is improved.

The present application relates to the technical field of capturing, and discloses a capturing method, an electronic device, a readable storage medium, and a program product. In the method, if an electronic device detects that a user performs a zoom operation on a captured image in a low-light environment, the captured image can be displayed at a target frame rate, the target frame rate being greater than a first lower limit value of a preset frame rate range of the electronic device and a first frame rate corresponding to a current exposure time. For example, the electronic device can increase the first lower limit value to a second lower limit value, use the second lower limit value as the target frame rate when the first frame rate is less than the second lower limit value, and display the captured image on the basis of the target frame rate. For another example, after obtaining the first frame rate, if the first frame rate is less than the first lower limit value, the electronic device does not display the captured image at the first lower limit value, but displays the captured image at the target frame rate greater than the first lower limit value. In the method, by increasing the display frame rate of the captured image, the display smoothness of the captured image during zooming in the low-light environment is improved.

A machine learning (ML)-based process proximity correction (PPC) method includes receiving a first layout of an after clean inspection (ACI) including patterns for manufacturing a semiconductor device, extracting features of a first pattern from the first layout, generating a prediction model through ML based on the features of the first pattern, generating an ACI target having a maximum process margin by comparing an upper limit value and a lower limit value of the ACI for at least one condition, generating a second layout of an after development inspection (ADI) by correcting the first layout to correspond to the ACI target, and predicting the ACI through the prediction model, based on the second layout of the ADI.

The invention relates to a device and a method for harvesting timber using a hydraulically controlled felling head (1) which comprises a gripper and saw unit, wherein the gripper and saw unit has two pivotable gripper arms (4) for harvested material (2) and a cutting element (6) for separating the harvested material (2), wherein the gripper arms (4) can be pivoted into an open state by applying pressure to a first hydraulic line (12a), and the gripper arms (4) can be pivoted into a closed state by applying pressure to a second hydraulic line (12b). According to the invention, the felling head (1) is provided with an opening width sensor (19), and a pressure sensor (15) is arranged in the second hydraulic line (12b), wherein the opening width sensor (19) and the pressure sensor (15) are connected to a controller (13) which is designed to detect a closed state by the pressure (p) measured by the pressure sensor (15) exceeding a predetermined lower limit value (Gp) and to generate a warning signal when a predetermined upper limit value (GW) of the opening width (W) is simultaneously detected in the closed state.