832results about "Voltage-current phase angle" patented technology

The invention relates to the technical field of power supply detection, and discloses a fire-fighting equipment power supply detection method and system.The detection method comprises the following steps that voltage fluctuation, current phase and ripple coefficients are collected through a multi-channel sensor group, a feature sequence is generated through sliding window noise reduction, the Euclidean distance is calculated through Z-score standardization, and a calibration instruction is generated when a threshold value is exceeded; kalman filtering adjusts frequency output detection parameters, fast Fourier transform is executed to extract harmonic amplitude to generate a suppression vector, and a least square reconstruction model outputs a state identifier; according to the method, voltage, current and ripples are collected through multiple channels, anti-interference performance and data integrity are enhanced through sliding window noise reduction, a threshold value is adjusted through Z-score and Euclidean distance self-matching, sampling frequency and detection parameters are optimized through Kalman filtering, harmonic characteristics are extracted through FFT, and the state is evaluated through a least square reconstruction model. And a multi-dimensional classification system is constructed by fusing the distortion rate and the phase deviation, so that the detection precision, the sensitivity and the response real-time performance are improved.

The invention relates to the technical field of electrical detection, in particular to an electricity meter load monitoring method and system based on an electric energy quality analyzer, and the method comprises the following steps: extracting three-phase voltage phase deviation characteristics in a disturbance period, combining with the comparison of a frequency band change trend and fundamental frequency power, recognizing an interference coupling section, and analyzing a jump frequency point; and outputting an ammeter load monitoring result. According to the method, the phase deviation angle of the three-phase voltage is extracted in the voltage disturbance period, and the cross-phase synchronization index is constructed, so that the synchronous response characteristics of different loads to disturbance can be accurately revealed, and the accuracy of load response attribution judgment is enhanced. On the basis of cross-phase synchronous analysis, a corresponding relation between frequency band characteristics and response attribution is constructed, so that load response subdivision has a phase difference identification capability and a frequency behavior calibration capability, and the discrimination robustness under a multi-source interference background is improved.

At least one example embodiment provides a system for controlling a heater in a non-combustible aerosol-generating device, the system comprising a memory storing computer-readable instructions and a controller configured to execute the computer-readable instructions to cause the non-combustible aerosol-generating device to apply a first power to the heater based on a first preheat temperature determine an estimated energy applied to the heater during application of the first power, and apply a second power to the heater based on the estimated energy, an energy threshold and a second preheat temperature, the second power being less than the first power.

The invention relates to a time-varying power high-precision calculation technology of an electric drive system under strong electromagnetic noise interference, and mainly solves the problem of inaccurate power calculation of the electric drive system under strong electromagnetic environment noise and frequency time-varying fluctuation scenes. According to the core technology, a dominant frequency fluctuation curve of a signal is obtained through dynamic tracking of a dominant frequency, and a dynamic band-pass filter changing along with the dominant frequency of the electric drive system is constructed; suppressing pulse noise by combining amplitude self-adaptive filtering of a nonlinear weighting function; a phase demodulation technology fusing zero crossing point correction and Hilbert transform is adopted to eliminate the phase interference problem caused by complex waveforms and weak noise signals; and finally, establishing a time-varying power physical model based on the sliding window. According to the technology, the power calculation accuracy of the electric driving system under the conditions of strong field environmental noise and continuous main frequency conversion is remarkably improved.

The invention belongs to the technical field of intelligent substations, and particularly relates to an intelligent nuclear phase method and system for a substation. According to the method, a dynamic priority evaluation model is constructed, multi-source data of four kinds of basic factors including voltage phase difference, environment temperature and humidity, equipment vibration and historical errors are synthesized, and a fuzzy comprehensive evaluation method is utilized to calculate weights and dynamically sort the weights; a multi-port phase scattering model is constructed based on transformer substation topology, impedance mismatch points are analyzed by means of a Smith chart, and dual-stage optimization is implemented; constructing a three-layer decision input set according to the optimization model, designing a fuzzy logic driven adaptive rule engine, dynamically outputting a working condition level and matching a nuclear phase strategy; multi-dimensional quality evaluation, dynamic updating of factor weights and optimization of fuzzy model parameters are carried out by monitoring indexes such as reflection coefficients in real time, abnormal mode recognition and compensation strategy solidification are realized by fusing LSTM and a graph neural network, a self-evolution closed-loop system is formed, and finally, crossing of a nuclear phase process from accurate matching to autonomous evolution is realized.

The invention discloses a log data processing method based on cable phase measurement, and particularly relates to the field of log data processing, which comprises the following steps: constructing a feature vector set containing multi-dimensional description, and establishing a classification reference of short-term and long-term feature abnormal modes of each cable number; monitoring the latest log record of each cable in real time, and generating abnormal recognition results corresponding to short-term fluctuation and long-term drift; establishing a first-level repair strategy based on short-term fluctuation anomaly characteristics, and generating a repair value sequence by using an interpolation algorithm to reconstruct short-term fluctuation anomaly data of the phase log; establishing a second-level repair strategy based on the long-term migration abnormal characteristics, and reconstructing the long-term migration abnormal data of the phase log based on polynomial fitting and piecewise regression; and performing abnormal identification on the data after the repair execution is finished again, judging whether the phase log data is repaired or not, if so, ending the log data repair, and if not, sending out a phase abnormal alarm signal.

The invention relates to an AC-DC integrated grounding fault positioning method and system, and the method comprises the steps: collecting the potential change data of a DC power supply system and the frequency characteristic data of an AC power supply system, and determining the electrical signal characteristics of stray current corrosion; decomposing the electric signal by using wavelet transform, and extracting direct-current and alternating-current components; determining a fault type according to the component amplitude; analyzing the potential gradient and the stray current flow direction in combination with a line topological structure, and determining the position of a fault point; measuring resistance to determine a grounding loop, and analyzing the correlation between corrosion distribution and electrical parameter characteristics; evaluating the influence of corrosion on the grounding path in combination with the material resistivity; according to the method, faults can be accurately recognized, fault points can be accurately positioned, the corrosion degree and the influence of the corrosion degree on the system can be evaluated, and effective support is provided for safe operation and maintenance of a subway power supply system.

The invention relates to the technical field of pulse resistance measurement, in particular to a Poe-based pulse type charging and discharging battery internal resistance measurement method. The method comprises the following steps: acquiring a total current state signal and a charging state signal of a battery pack in real time through a controller, and analyzing the total current state signal and the charging state signal to obtain a charging mode identifier; judging whether the battery pack is in a charging state or an idle state based on the charging mode identifier, if the battery pack is in the charging state, activating a bus power supply mode, and acquiring module working electric energy from a control bus through a Poe network interface; and when the charging state is judged, controlling the pulse injection unit to superpose high-frequency pulse charging current to the battery pack, and synchronously acquiring voltage transient data and current waveform data in a pulse action period according to the working electric energy of the module. Through high-frequency pulse charging and discharging, real-time internal resistance calculation and dynamic state monitoring, the problems of hysteresis, insufficient precision and difficult state judgment in traditional battery internal resistance measurement and health assessment are solved.

The invention relates to relay protection technology, specifically a method, system, and medium for fault arc suppression in distribution networks using closed-loop self-healing control. When a fault is detected in the distribution network, transient changes in the measured and virtual phase currents of each phase are obtained. The Pearson correlation coefficient between these changes is calculated to identify the target fault phase. The neutral point-to-ground voltage value is retrieved, and the target fault phase's voltage is adjusted to zero based on this value. The current from the fault phase, when its voltage is zeroed, is acquired. An injected current is then compensated at the neutral point to match this value, ensuring both the ground fault current and the fault phase voltage are reduced to zero. This method enhances the applicability of arc suppression for grounding faults in distribution networks.

The invention belongs to the technical field of power system measurement, and relates to a three-phase power parameter wireless synchronous measurement and vector analysis method and system, and the method comprises the following steps: generating and broadcasting a synchronous pulse code containing triggering phase information; generating a predicted phase angle; obtaining a comprehensive phase deviation value; performing dynamic feature separation processing on the comprehensive phase deviation value to generate a slowly-varying propagation delay feature and a transient prediction error feature; injecting the prediction error characteristics into a local phase predictor for calibration; acquiring phase voltage / current data based on the compensated sampling time, and calculating a fundamental wave effective value and a phase angle relative to a local calibration time reference; and packaging the fundamental wave effective value, the phase angle and the local timestamp into a simplified data packet and transmitting the simplified data packet to an analysis terminal. According to the method, the problems that in a traditional mode, satellite time service rejects signals in a substation indoor or underground scene, and synchronization interruption is easily caused by electromagnetic interference are solved.

The invention relates to the technical field of fault testing, in particular to a dry-type air-core reactor turn-to-turn short circuit monitoring method based on a magnetic field difference method. According to the method, regularization constraint is introduced in an initial baseline stage to construct a reference electromagnetic coupling matrix, a heat accumulation index is recursively analyzed based on three-phase current energy, a thermally-induced magnetic field drift model is fitted in combination with magnetic field residual errors, and combined with combined constraint of the reference electromagnetic coupling matrix and the thermal drift model, a three-phase electromagnetic coupling model is established. The normal thermally induced magnetic field drift component is dynamically stripped in real-time monitoring; and under the constraint of a reference electromagnetic coupling matrix, fitting and optimizing a current vector through weighted least square state estimation, and integrating magnetic field and current two-dimensional deviation to obtain a structure consistency deviation index for fault monitoring. According to the invention, monitoring is carried out in consideration of a linear electromagnetic transfer rule and nonlinear thermal drift compensation, a complex magnetic field environment and a variable load operation condition of the dry-type air-core reactor are adapted, and continuous and reliable monitoring guarantee is provided for long-term stable operation of equipment.

The invention discloses a transformer area phase identification method and system based on non-contact voltage measurement. The method comprises the following steps: acquiring voltage data of each monitoring node on a power line of target power distribution network transformer area power transmission equipment; performing intelligent judgment on the voltage data, and generating a corresponding high-frequency noise scene signal; in response to the high-frequency noise scene signal, a monitoring result of the target power distribution network area power transmission equipment is obtained in the process of processing the voltage data based on a Kalman filtering algorithm, the processing process is configured to obtain a first prediction result corresponding to each monitoring node based on a state prediction equation, and the first prediction result is configured to obtain a second prediction result corresponding to each monitoring node; inputting a fusion analysis result of a measurement noise matrix determined by a Bayesian fusion algorithm for each first prediction result and a feature extraction result of the corresponding voltage data into an observation update equation; and carrying out transformer area phase identification on the target power distribution network transformer area power transmission equipment based on a monitoring result so as to realize accurate detection of weak signals.

The invention discloses a power frequency phase adaptive acquisition device, and relates to the technical field of electric power signal measurement, the device acquires electric field data at a gap through an electric field sensor integrated on an edge shell, calculates electric field intensity fluctuation, and generates interference diagnosis information in combination with a preset interference determination threshold value; when the interference diagnosis information shows that effective interference exists, the electric field intensity variable quantity is calculated, a mapping model is established based on a proportionality coefficient obtained through an experiment so as to obtain zero crossing point offset, and the sampling trigger moment of a zero crossing point detection module is corrected; the clock synchronization module calculates a phase difference by taking the corrected trigger moment as a reference, dynamically adjusts a calibration frequency by combining a phase difference threshold value, and outputs a synchronized system clock signal; and the control system takes the synchronized system clock signal as a trigger signal, collects power frequency phase data according to a power frequency period, and stores the power frequency phase data to a database through a transmission unit, thereby realizing high-precision power frequency phase collection.

The invention discloses an electricity stealing behavior detection method and system based on an intelligent electric energy meter, and the method comprises the following steps: constructing a phase locking reference frame at the end of the intelligent electric energy meter, synchronously collecting a voltage phase and a current phase through high-precision time, generating a direction discrimination baseline, setting a zero-power crossing point and a direction overturning threshold value, and carrying out the detection of an electricity stealing behavior. Outputting a direction baseline consistency index as a direction identification reference; according to the invention, through phase locking, high-precision synchronization, neutral line drift analysis, multi-table data alignment and phase disturbance verification, accurate identification and causal confirmation of a current backward flow behavior are realized, a disturbance user is reversely positioned in combination with a disturbance fingerprint, an intervention instruction is output, and an identification-verification-positioning-control closed loop mechanism is constructed. And the anti-electricity-stealing capability and the metering accuracy of the intelligent electric energy meter in a complex power supply environment are obviously improved.

The invention relates to the technical field of power distribution network fault early warning, and discloses an early warning system and method for a power distribution network ground fault. The data acquisition module of the system acquires multi-mode monitoring data such as zero-sequence current waveform, grounding wire current amplitude phase, insulator leakage current and environment temperature and humidity of the power distribution network in real time, and comprehensively reflects the operation state of the power distribution network. And the feature fusion module performs spatial-temporal feature compensation on the multi-modal monitoring data to generate a fault feature tensor, so that the insulation degradation evolution period of the topological node of the power distribution network is determined, and the insulation state change is accurately evaluated. And the risk deduction module analyzes a dynamic communication path of the topological structure of the power distribution network, performs fault conduction modeling, determines a ground fault risk situation level in combination with multi-modal monitoring data, and comprehensively considers fault conduction characteristics and operation conditions. The early warning decision module generates a dynamic early warning strategy according to the insulation degradation evolution period and the risk situation level, and the early warning mode is flexibly adjusted.

The invention discloses a transformer area current characteristic identification method based on a correlation peak judgment method, and the method comprises the steps: collecting the synchronous phase information of a power grid, and generating and injecting a unique phase coding characteristic signal; current signals are collected at key nodes of the transformer area, and phase information is extracted; constructing a dynamic self-adaptive phase relation network, and extracting a feature vector with topology invariance; correlation analysis is carried out on the extracted feature vectors and a standard template, and an identification result is determined through adaptive correlation peak judgment; and dynamically adjusting system parameters according to an identification result. The method of combining phase coding and topology invariant features is adopted, and the method has the advantages of being high in anti-interference capacity, good in environment adaptability and high in recognition precision.

This invention relates to a system and method for calibrating energy meters, designed to enhance the accuracy of electrical power measurements. The system incorporates a computing device with specialized calibration software, interfaced with multiple energy meters via a network switch. Each energy meter is equipped with a CPU and DSP, facilitating precise phase angle measurements. A configurable three-phase reference source, connected via power cables, supplies standard calibration signals to the meters. The DSP measures phase angles based on calibration commands triggered by control signals received by the CPU. These measurements are then transmitted to the computing device, which calculates necessary offset corrections. The corrections are subsequently communicated back to the CPU for adjustment of the energy meters' analog-to-digital converter settings, thereby ensuring the meters' outputs are accurately aligned with calibrated standards. This system provides a robust framework for reliable, high-precision energy meter calibration.

The invention relates to the technical field of power system relay protection, in particular to a self-adaptive direction overcurrent protection method and system based on real-time load flow calculation. According to the method, operation data are collected and preprocessed in real time, current operation state parameters are obtained based on load flow calculation, and the action current constant value of direction overcurrent protection and the action angle constant value of a direction element are adjusted in a self-adaptive mode in combination with a network topology structure and protection configuration information. When the fault is judged, the real-time operation data and the adjusted action constant value are combined, so that the accurate judgment of the fault direction of a complex power grid structure including a distributed power supply, a micro-grid or an alternating current / direct current hybrid connection and the like and the reliable execution of the protection action are realized; therefore, the problems that a conventional protection constant value is fixed and is difficult to adapt to the change of a power grid operation mode and the fault characteristic change is caused by the access of a distributed power supply are effectively solved, and the selectivity, sensitivity and adaptability of overcurrent protection are remarkably improved.

According to the etching end point detection system for improving the TSV etching uniformity, the etching end point is accurately judged by monitoring electrical parameter changes in the etching process in real time, and therefore the TSV etching uniformity and quality are improved. The electrode laying device comprises a central electrode, a peripheral annular array electrode group and an electrical parameter monitoring module; a data processing and feedback control module; and an end point determination and alarm module. The electrical parameter monitoring module of the electrode laying device is connected to the data processing and feedback control module, and the data processing and feedback control module is connected with the end point judgment and alarm module.

The invention relates to a multi-source micro-grid inertial support detection method and device and a storage medium. The method comprises the steps that S1, a discretized original voltage sequential sequence and a discretized original current sequential sequence are collected; s2, respectively extracting a first voltage sequence and a first current sequence corresponding to a measurement moment based on the original voltage sequential sequence and the original current sequential sequence; s3, obtaining a measurement frequency and a voltage and current phase difference based on the first voltage sequence and the first current sequence, and obtaining an active power based on the voltage and current phase difference; s4, obtaining a reference frequency and a reference power based on the measurement frequencies and the active powers at the plurality of measurement moments; and S5, based on the reference frequency and the reference power, combining the measurement frequency and the active power at the measurement moment to obtain the equivalent inertia. Compared with the prior art, the method has the advantages that the measurement accuracy of the equivalent inertia in the multi-source micro-grid environment is improved, and the like.

The invention provides a broadband portable measuring system applied to rock and ore electrical parameter measurement, which comprises a sample frame, an execution module and a control terminal, and is characterized in that the sample frame comprises a first clamp box and a second clamp box for fixing a rock and ore sample, and a scale for measuring the length of the rock and ore sample; the scale is a connecting shaft of the first clamp box and the second clamp box; the execution module is electrically connected with the first clamp box and the second clamp box and is used for collecting response signals of the rock and ore samples through the emitted excitation signals; and the control terminal is electrically connected with the execution module, and is used for issuing a control instruction to control the execution module, receiving the collected data uploaded by the execution module, and calculating various electrical parameters of the rock and ore sample according to the collected data, thereby overcoming the defects that the existing measurement system can only support a smaller electrical impedance measurement range and a narrower frequency band measurement width; the measurement precision is low; and the measurement efficiency is low.

The invention relates to the technical field of electric power measurement online monitoring. The invention discloses a CVT error calculation method and device based on a virtual standard algorithm and a storage medium, and the method comprises the steps: collecting the voltage original waveform data of a plurality of CVTs in a homologous state in real time, and calculating the amplitude and phase of the data; constructing a steady-state data set; calculating an initial virtual standard; calculating an initial voltage ratio difference value and an initial voltage angle difference value; inverting a real-time virtual standard; calculating an overall virtual standard; calculating an instantaneous voltage ratio difference value and an instantaneous voltage angle difference value; and outputting a CVT state judgment result. According to the method, the accuracy of CVT error calculation is effectively improved, the state of the mutual inductor can be more accurately judged, and a powerful guarantee is provided for stable operation of a power system.

The present invention relates to a hair removal device, such as an electric shaver or epilator, comprising a hair cutting unit, a motor for driving the hair cutting unit, a measurement unit for measuring motor current and / or induced voltage and a cutting activity determinator for determining cutting activity from the half cycles of the signal of said measurement unit, wherein a wear determination unit is provided for determining wear of the hair cutting unit from the cutting activity signal of said cutting activity determinator.

The invention provides a three-phase alternating current phase angle measuring device and method, and belongs to the technical field of phase angle measurement. The three-phase alternating current phase angle measuring device comprises a main control chip and two metering chips. The main control chip has a fundamental wave zero-crossing function, the main control chip collects a phase angle A based on a fundamental wave zero-crossing interruption function and linear interpolation, the precision of the phase angle A is high, harmonic interference can be effectively avoided, the two metering chips collect a phase angle B and a phase angle C respectively, a single-phase chip and related peripheral circuits are reduced, the price is lower, and the cost is lower. The cost advantage is obvious.

The invention discloses a high-power and frequency-adjustable gyrotron loading test system for nuclear fusion, which relates to the technical field of nuclear fusion and comprises a 2-megawatt coaxial gyrotron with adjustable frequency of 170 / 240GHz and a loading test platform. The loading test platform comprises a gyrotron part loading system, a strong magnet system, a vacuumizing system, a power supply system, a load system, a cooling system, a monitoring and diagnosing system and a control system. The component loading system is used for precise assembly; the strong magnet system provides an adjustable strong magnetic field; the vacuumizing system maintains ultrahigh vacuum; the power supply system comprises a cathode power supply and a body power supply, and the body power supply is used as a high-voltage amplifier to realize 10kHz rapid power modulation; the cooling system provides independent active cooling; the load system simulates a real load; comprehensive detection of the monitoring and diagnosis system; and the control system realizes coordinated control and rapid protection. According to the invention, a complete solution is provided for development, test, operation and maintenance of the 2-megawatt-level and frequency-adjustable gyrotron.

The invention discloses a cable frequency spectrum phase detection method, device and equipment and a medium, and the method comprises the steps: employing two high-speed ADC modules to collect the input of two frequency signal sources in parallel, and each ADC is responsible for collecting the time domain data of one signal source; in a signal input stage, the FPGA is responsible for time sequence synchronization; inputting the signal data of each channel into a parallel processing module in the FPGA, and extracting the time domain characteristics of the signals through parallel calculation; the FPGA executes time domain analysis to obtain initial phase information of the signal; and signal synchronization and phase calculation: performing phase difference calculation of the dual-channel signals according to the obtained initial phase information through the FPGA, obtaining an initial phase relationship of the signals, and determining relative time delay of the signals. The two high-speed ADCs are used for collecting signals in parallel, accurate time sequence synchronization is achieved through the FPGA, the multi-channel signal synchronization problem is effectively solved, and consistency of signal data of all channels and high-precision phase detection are ensured.

The invention discloses a power grid power flow real-time calculation and state estimation method and system based on a PMU, and belongs to the technical field of electric measurement and electric fault positioning. The method comprises the following steps: synchronously measuring electrical variables, including a voltage phasor and a current phasor, of a power grid node through PMU equipment to obtain synchronous phasor data, and verifying time and topology consistency; the power grid observability grade is judged based on PMU configuration node distribution corresponding to the verified electric measurement data; directly generating a real-time state estimation result through linear calculation based on PMU electric measurement data if the whole domain is observable; and if a part is observable, fusing PMU and SCADA data, carrying out nonlinear state estimation through a weighted least square method, distributing a high weight for the PMU electrical measurement data, and dynamically adjusting the SCADA weight to suppress bad data. According to the method, through observability adaptive judgment, the precision and efficiency of state estimation are improved, a data basis is provided for power grid fault positioning, and the method is suitable for practical application scenes of various PMU coverage degrees.

The invention discloses an electric power system transient stability rapid response control method and system, and relates to the technical field of electric power systems, and the method comprises the steps: collecting a transient harmonic current signal generated by a power grid fault in real time through a harmonic detection unit connected to a DC bus of an energy storage converter, and calculating the phase offset of the transient harmonic current signal; generating a power control instruction through a pre-configured hardware mapping circuit based on the phase offset; acquiring a current differential signal by using a power grid line current sensor, and identifying a path of transient energy flowing to a key unit based on a power grid topological structure; for the path, dynamically forming a virtual high-impedance wall on the target line; and on a consumption path predefined according to the power grid topological structure, controlling the energy storage converter to operate in a current source mode and configuring a reverse power characteristic so as to absorb the energy flow turned by the virtual high-impedance wall.

The invention discloses a frequency sweep measurement method and system. The method comprises the following steps: acquiring a fundamental frequency reference phase of each measured equipment access point at a measurement moment; executing rough scanning of the first-stage injection; analyzing the coarse scanning response data to identify a target frequency band which needs to be subjected to second preset resolution measurement; executing fine scanning of second-stage injection for the target frequency band; and analyzing the fine scanning response data, and obtaining a stability contribution evaluation result of each tested device to the power grid system based on an analysis result of the fine scanning response data and an analysis result of the coarse scanning response data. According to the scheme of the invention, the method can achieve the quick recognition of the potential key frequency region in a broadband range through the hierarchical rough scanning and fine scanning strategies, and avoids the time-consuming high-resolution measurement in a whole frequency band. And then, high-resolution fine scanning is performed on the identified target frequency bands in a targeted manner, so that accurate and detailed response data can be obtained in the key region.

The invention belongs to the technical field of electric leakage safety protection, and discloses a remotely controllable electric leakage safety protection plug, which comprises an electric leakage risk preliminary identification module, a magnetic core saturation risk identification module, an advanced electric leakage risk diagnosis module and an abnormal remote difference control module. By setting a magnetic core saturation and electric leakage risk collaborative diagnosis mechanism, parameters such as direct current offset percentage and the like can be analyzed in real time to judge the magnetic core saturation risk, and then the electric leakage risk judgment result is combined to comprehensively identify the operation refusal risk, trigger voltage and current phase analysis and insulation resistance test, so that the electric leakage detection accuracy is improved, and the operation refusal caused by magnetic core saturation is prevented; and the power utilization safety is ensured. By setting a four-stage progressive diagnosis mechanism of preliminary electric leakage identification, magnetic core risk screening, advanced electric leakage risk diagnosis and differential management and control, electric leakage can be accurately identified, magnetic core saturation refusal operation can be prevented, remote intelligent management and control can be realized, and power utilization safety and management efficiency can be improved.