41 results about "Contamination index" patented technology

The invention relates to the technical field of electric energy quality monitoring and treatment, and discloses an electric energy quality abnormity traceability and purification strategy generation system, which comprises an electric energy acquisition module, a feature analysis module, an abnormity traceability module, a pollution evaluation module, a parameter optimization module and a strategy generation module. The electric energy acquisition module acquires waveform data of key nodes of a group network in real time and sets a monitoring interval; the feature analysis module decomposes the spectrum features to generate pollution feature vectors; the abnormity traceability module extracts a core index to establish a traceability rule; the pollution evaluation module identifies a propagation path and calculates a pollution index; the parameter optimization module deduces an optimal parameter generation deviation sequence; and the strategy generation module integrates the sequence to form a purification strategy. The system realizes accurate traceability and dynamic management of abnormities, improves analysis comprehensiveness and strategy intelligence level, and is suitable for power grid electric energy quality management and control.

The invention relates to the technical field of soil pollution analysis, and discloses a soil heavy metal intelligent evaluation method, system and terminal, and the method comprises a multi-source heterogeneous data fusion and preprocessing step, a dynamic spatial interpolation modeling step and an intelligent visualization and decision support step. The system corresponds to the method, and the terminal equipment corresponds to the system. According to the method, comprehensive data support for soil heavy metal pollution is realized through multi-source heterogeneous data fusion and preprocessing; through dynamic spatial interpolation modeling and a dynamic parameter adjustment mechanism, high-precision grid surface layer generation is realized, and the fitting precision of pollution spatial distribution is improved; intelligent pollution grading and multi-factor dynamic calculation of pollution indexes are realized through self-adaptive grading and pollution index calculation, and the accuracy of an analysis result is improved; through intelligent visualization and decision support, a dynamic and visual decision basis is provided for multi-department collaborative governance and risk early warning.

The invention belongs to the technical field of regional soil pollution evaluation and risk management, and particularly relates to a pollution grading evaluation and point source pollution identification method based on a regional soil environment background. The method comprises the following steps: determining a target area range and soil target pollutants; obtaining a current-stage soil environment background concentration data set of the target area, and calculating a statistical index of the data set; arranging regional soil pollution monitoring points, and monitoring the target pollutant content of the soil sample; and finally, the constructed pollution index evaluation model based on the soil environment background is adopted to calculate the single or combined pollution index of the soil at each point, the regional soil pollution grade and the environment quality are quantitatively evaluated, and the soil pollution point source is further identified. According to the method provided by the invention, based on the soil environment background content, the uncertainty of overestimation of non-point source pollution in a traditional soil pollution evaluation method is optimized, and the point source pollution point location can be accurately positioned.

The application relates to an anti-pollution performance accelerated testing device and method of a hydrogen production diaphragm of alkaline electrolytic water, and belongs to the field of electrochemistry. The method simulates the process of catalyst deposition under the real working condition of an electrolytic tank by adopting dynamic addition of catalyst particles, is closer to the actual operation environment of the electrolytic tank, introduces an anti-pollution index as an evaluation index based on test data, realizes quantitative evaluation of the anti-pollution performance of the diaphragm, can reflect the stability of long-term operation, and can also be used for estimating the failure time of the diaphragm and can be used for guiding operation and maintenance and selection.

The invention discloses a pollution grade evaluation method for an urban industrial pollution site, and relates to the technical field of pollution detection, and the method comprises the steps: employing an unmanned aerial vehicle-mounted air pollution detection instrument for inspection, collecting air pollution concentration data in real time, separating a background from a hot spot through a grid mean-standard deviation model, and carrying out the weighting to generate an air pollution index, based on the air pollution index, dynamically regulating and controlling the soil sampling density, carrying out secondary gridding point distribution in a field area, measuring soil pollution concentration data, and obtaining the soil pollution index by using the same'background + hot spot 'weighting strategy; fusing the soil pollution index and the air pollution index as a comprehensive pollution index, and comparing a four-level threshold value to immediately judge the site pollution level; according to the method, air-ground multi-dimensional anomalies are taken into consideration, high-risk area encryption sampling and low-risk area economic evaluation are realized, and an accurate, efficient and visual decision basis is provided for urban brown land redevelopment, treatment and resource release.

The application belongs to the technical field of vacuum equipment maintenance, and specifically discloses a molecular pump automatic purging pre-cleaning system and method. The system comprises a detection module, a control module and an execution module. The detection module collects flow, pressure, temperature and vibration parameters in real time through various sensors, obtains a pollution index PI through normalization and weighted operation, and accurately determines the pollution grade. The control module combines PID and fuzzy control algorithms and dynamically generates cleaning instructions in combination with an adaptive learning strategy. The execution module uses high-purity inert gas to complete the purging operation. The application solves the problems of low efficiency, unstable effect, easy damage to equipment and poor universality of traditional manual cleaning, can automatically adjust the cleaning cycle according to the load of the molecular pump, and has good hardware and software compatibility. The scheme has high automation degree and good cleaning effect, can reduce operation and maintenance cost and prolong the service life of the equipment, and is suitable for high-vacuum scenes such as semiconductor manufacturing, vacuum coating and particle accelerators.

The invention relates to the technical field of membrane filtration, in particular to a membrane pollution state determination method based on multi-dimensional operation parameter association. The membrane pollution state determination method based on multi-dimensional operation parameter association comprises the following steps: acquiring multi-dimensional input parameters of an ultrafiltration membrane system in a current operation state; and preprocessing the obtained multi-dimensional input parameters to obtain a multi-dimensional parameter data set. And inputting the multi-dimensional parameter data set into a pre-established optimal analysis model to obtain a current membrane pollution index PI. Comparing the current membrane pollution index PI with each preset pollution grade range, quantitatively judging to obtain the pollution state grade of the ultrafiltration membrane, and determining treatment measures according to the pollution state grade. The method has the technical effects and advantages that the problem of single historical working condition data is solved, the data preprocessing process is perfected, the model design is reasonable, the adaptability is high, the operation is simple and convenient, the practicability is high, and the service life of the ultrafiltration membrane is prolonged.

This invention provides a method and system for multidimensional risk coupling assessment and dynamic prediction of environmental capacity for heavy metals in soil. It relates to the field of data processing technology. Based on remote sensing spectral data and environmental physicochemical covariates of the target area, it inverts and generates heavy metal content data covering the target area. An integrated pollution index is calculated based on the heavy metal content data. Probability distributions are configured for exposure parameters of various population groups under different exposure pathways. Random sampling is performed on each exposure parameter according to the probability distributions. Health risk probabilities are determined based on the heavy metal content data and the sampled exposure parameters. The current environmental capacity is calculated based on risk control benchmarks and heavy metal content data. The current environmental capacity is extrapolated based on a preset annual heavy metal residue rate to obtain overload risk zones. This invention can extrapolate the changes in soil heavy metal environmental capacity over multiple future years, and can delineate and issue early warnings for capacity overload areas.

The present application relates to the technical field of power quality monitoring and treatment, and discloses a power quality abnormality tracing and purification strategy generation system, which comprises power collection, characteristic analysis, abnormality tracing, pollution assessment, parameter optimization and strategy generation modules.The power collection module collects grid key node waveform data in real time and sets a monitoring interval; the characteristic analysis module decomposes frequency spectrum characteristics to generate a pollution characteristic vector; the abnormality tracing module extracts core indexes to build a tracing rule; the pollution assessment module identifies a transmission path to calculate a pollution index; the parameter optimization module deduces optimal parameters to generate a deviation sequence; and the strategy generation module integrates the sequence to form a purification strategy.The system realizes accurate abnormality tracing and dynamic treatment, improves analysis comprehensiveness and strategy intelligentization level, and is suitable for power grid power quality management and control.

The invention discloses a detection method and system for agricultural land soil heavy metal pollution, and belongs to the technical field of soil heavy metal detection.The detection method comprises the steps that a dynamic grid division method is adopted for delimiting a detection area, and the detection area is divided into a plurality of space units; carrying out adaptive filtering and noise reduction processing on the in-situ rapid spectral signal to obtain denoised spectral data, and calculating the initial content of heavy metal elements in each space unit; constructing a multi-feature data set, training the multi-feature data set, and establishing a heavy metal pollution degree comprehensive evaluation model; and inputting the spatial unit feature data of the farmland to be detected into the comprehensive evaluation model, and outputting the comprehensive pollution index and risk level of each unit. According to the method and system for detecting heavy metal pollution of agricultural land soil provided by the invention, multi-source information can be fused, rapid and accurate detection can be realized, and the method has a dynamic risk assessment capability for detecting heavy metal pollution of agricultural land soil.

The invention relates to an intelligent disinfection control method and device for an electric otoscope. The method comprises the following steps: synchronously acquiring pollution spectrum data, ultraviolet intensity reference data, disinfection temperature and humidity data and a probe insertion state signal of an endoscopic optical window at the front end of a probe before disinfection is started to obtain a disinfection initial state vector; calculating a dynamic pollution index according to the disinfection initial state vector, the historical use frequency of the probe and the adjacent use time interval; matching a basic disinfection parameter according to the dynamic pollution index and a preset disinfection mapping table, and performing parameter dynamic calibration on the basic disinfection parameter according to the index deviation degree to generate a personalized disinfection protocol; performing process protection control in the process of executing the personalized disinfection protocol; and after disinfection is finished, carrying out cumulative ultraviolet dose standard verification and pollution spectrum data comparison verification. The reliability of the disinfection process is remarkably improved, and the risk of cross infection caused by human negligence is avoided.

The invention belongs to a mass spectrometry technology, and particularly provides a mass spectrometer anti-pollution performance dynamic monitoring method which comprises the following steps: A1, alternately injecting samples with the same concentration and blank products, and collecting a mass spectrum full-scanning spectrogram in real time; a2, extracting a time sequence pollution characteristic index according to the spectrogram, wherein the index comprises a background noise rise rate delta Nt / N0; a3, calculating a dynamic pollution index according to the characteristic index; a4, establishing a method for predicting a future cleaning critical point based on a dynamic pollution index sequence; and A5, a pollution boundary response threshold value is set, and a pollution cleaning strategy is fed back. The method has the advantages of high pollution monitoring capability and the like.

The invention discloses a method and a system for determining heavy metal pollution characteristics of water sediment, and relates to the technical field of environment monitoring and water environment governance, the system is characterized in that surface sediment samples are regularly collected at different positions of water in a mine area and an industrial gathering area, and a metal element data set and a reference data set are established; calculating a single-factor pollution index, and judging whether single metal exceeds the standard or not; integrating the single-factor pollution indexes to obtain a comprehensive pollution index, and determining the overall pollution level; whether manual input pollution exists or not is judged by calculating the geocumulative index; according to the method, correlation analysis, principal component analysis, factor analysis and GIS space statistics are combined, multi-dimensional indexes are extracted, pollution source analysis coefficients are calculated, agricultural non-point source or industrial emission dominant pollution types are determined, and corresponding prevention and control strategies are generated. According to the method, multilevel feature recognition and source analysis of sediment heavy metal pollution can be realized, and a scientific basis is provided for water area pollution treatment and risk management and control.

The application relates to a metal contamination online monitoring method, system, electronic equipment, storage medium and computer program product. The method comprises the following steps: acquiring spectrum data in a process cavity in a semiconductor process; calculating an SPE statistic of the spectrum data according to a principal component analysis model; when it is judged that the SPE statistic exceeds a preset control limit, the spectrum data is regarded as a contamination spectrum, and a metal contamination analysis step is entered, which comprises the following steps: acquiring the closest reference spectrum based on the process time stage of the contamination spectrum, and calculating a difference spectrum of the contamination spectrum and the reference spectrum; calculating a contamination index of the metal to be measured based on the original spectrum data and the difference spectrum; matching the contamination index of the metal to be measured with a preset metal characteristic spectrum database; when a matching result meets a preset condition, it is determined that metal contamination exists in the process cavity, and an alarm signal is output. The application can realize early warning and rapid response of metal contamination, thereby improving the process control level and product yield of semiconductor manufacturing.

The application provides an ecological risk assessment method and system for heavy metal contaminated soil, and relates to the technical field of soil pollution control. The method comprises the following steps: obtaining a soil sample set of a target area; constructing a spatial grid model of the target area according to the soil sample set; determining a comprehensive pollution index of a grid unit according to concentration distribution information of heavy metals; performing time series analysis on the spatial grid model to predict a dynamic migration trend of the heavy metal concentration corresponding to the grid unit; determining an exposure threshold of different ecological receptors in the grid unit; generating an ecological risk heat map of the target area according to the comprehensive pollution index, the dynamic migration trend and the exposure threshold; and determining a risk position and a safe position in the target area according to the ecological risk heat map and a preset threshold. Therefore, the ecological risk of the target area can be more comprehensively and accurately evaluated, and the accuracy and reliability of risk assessment are greatly improved.

The invention discloses a pathology laboratory ventilation control method, device and equipment and a storage medium, and the method comprises the steps: obtaining the pollutant concentration and environmental parameters in a pathology laboratory in real time, the pollutant concentration being the concentration of volatile organic compounds, and the environmental parameters comprising humidity and temperature; determining the comprehensive pollution index of the pathology laboratory based on the concentration, temperature and humidity of the volatile organic compounds; matching a corresponding ventilation control strategy from preset multi-stage ventilation response strategies according to the comprehensive pollution index; and adjusting the operation state of the ventilation system in the pathology laboratory based on the ventilation control strategy. Compared with the prior art, the ventilation strategy of the laboratory is dynamically adjusted in real time according to the conditions in the pathology laboratory, the pollution gas treatment efficiency is improved, and the energy consumption is reduced.

The present application relates to the technical field of intelligent detection, and discloses a cheese microbial contamination early warning method and system, the method comprising: gradient heating of a cheese to be tested, collecting volatile organic compounds at different temperature stages to obtain a gas sample of the cheese to be tested; using a multi-parameter sensor array to detect the gas sample to obtain sensor response data of the cheese to be tested; determining a weight coefficient set of the sensor in contamination index prediction according to real-time response intensity and historical data reliability of the sensor in the multi-parameter sensor array; data fusion of the sensor response data based on the weight coefficient set to obtain a microbial contamination index of the cheese to be tested; when the microbial contamination index exceeds a preset contamination threshold, generating a multi-level microbial contamination report of the cheese to be tested based on the microbial contamination index; the present application can improve the efficiency of cheese microbial contamination early warning.

An air conditioner and a method for operating the same are provided. A method for operating an air conditioner including a compressor that compresses and discharges a refrigerant, and an indoor heat exchanger that heat-exchanges the refrigerant and indoor air, the method for operating an air conditioner according to an embodiment includes a step of accumulating a contamination index of the indoor heat exchanger using indoor humidity and a temperature of the indoor heat exchanger as factors; and a step of comparing the accumulated contamination index with a first reference contamination index, and in which if the accumulated contamination index is equal to or greater than the first reference contamination index, the heat exchanger cleaning process is performed.

The invention discloses a method for evaluating radioactive contamination of a decommissioned uranium mine area based on multi-source data fusion, and relates to the field of uranium mine area governance, and the method comprises the steps: detecting the radon exhalation rate, the radon concentration, the gamma air absorbed dose rate and the radionuclide content in soil of a to-be-evaluated decommissioned uranium mine area; calculating the public radiation dose according to the radon concentration and the gamma air absorption dose rate of the decommissioned uranium mine area; detecting the radioactive element concentration in the surface water of the decommissioned uranium mine area and the radioactive element content in the water sediment; calculating a Nemerow index as a comprehensive pollution index of the surface water based on the concentration of radioactive elements in the surface water; calculating a geocumulative index based on the content of radioactive elements in the water-based sediment as a comprehensive pollution index of the water-based sediment; and performing radioactive pollution assessment on the decommissioned uranium mine area according to the radon exhalation rate of the decommissioned uranium mine area, the public radiation dose, the radionuclide content in the soil and the comprehensive pollution index of the surface water and the water sediment.

The present application belongs to the technical field of coal-fired power generation, and discloses a method for predicting the coal contamination characteristics of a thermal power plant. S1 obtains the volume of flue gas generated by complete combustion of raw coal; S2 burns the weighed raw coal, respectively records the flame temperature, gas-phase potassium concentration and gas-phase sodium concentration in the combustion process, and calculates the average temperature, gas-phase sodium release amount and gas-phase potassium release amount in the combustion process; S3 collects the ash after combustion and weighs the mass of the ash, respectively detects the ash melting point and the mass proportion of sodium oxide and potassium oxide in the ash; S4 calculates the release rate of alkali metal and uses the release rate of alkali metal to solve the solid-phase contamination index, calculates the gas-phase contamination index and sums it with the solid-phase contamination index to obtain the total contamination index, that is, to realize the prediction of the contamination characteristics. Through the present application, the problem that the contamination characteristics cannot be obtained according to the gaseous alkali metal released by coal combustion is solved.

The invention is applicable to the technical field of neutral leaching of zinc-containing waste, and particularly relates to a zinc-containing waste neutral leaching process parameter control method which comprises the following steps: acquiring real-time state parameters of raw materials in a reaction kettle; obtaining a pollution index according to the real-time state parameter; obtaining a first target parameter based on the pollution index and the real-time state parameter; based on the correlation between the real-time state parameters and the first target parameters, determining a first correlation feature of each parameter in the first target parameters; determining a second correlation feature of each parameter in the first target parameters based on the correlation among the first correlation feature, the real-time state parameter and the first target parameters; determining at least one parameter adjustment feature based on the first association feature and the second association feature; and adjusting the first target parameter according to the at least one parameter adjustment feature to obtain a second target parameter. Therefore, according to the method provided by the invention, the sulfuric acid mist and noise pollution can be effectively controlled while the high zinc leaching rate is ensured.

The invention discloses an underground water combined pollution cooperative treatment method, and relates to the technical field of underground water pollution treatment, an online sensor network is utilized to automatically and continuously collect concentration data of at least two pollutants in underground water, the concentration data is transmitted to a processing unit in real time, delay and errors of manual sampling are overcome, and an accurate basis is provided for analysis. The pollution degree is quantified through the combined pollution index, and the index integrates the concentration of each pollutant, the standard limit value and the weight coefficient. And dynamically calculating the dosage and the treatment time of the treatment agent according to the pollution index. The feeding amount formula considers an index, a water body volume and a temperature dependent reaction efficiency constant; the processing time is automatically deduced from the adding amount, the index and the adding rate, experience errors are avoided, and repeatability is improved.

The invention relates to the technical field of fuse protection cover detection, and discloses a defect detection method and system for a drop-out fuse protection cover, and the method comprises the steps: obtaining a protection cover image, and obtaining defect features; classifying the defect features into structural defects and surface defects; calculating a structure defect index; comparing the structure defect with a historical structure defect to obtain a structure deterioration index, and judging the grade of the structure defect according to the structure defect index and the structure deterioration index; obtaining pollution characteristics, obtaining pollution characteristic change conditions in a preset time period, obtaining pollution indexes according to the pollution characteristic change conditions, and determining pollution grades according to the pollution indexes; and obtaining a defect degradation grade, and carrying out maintenance early warning. According to the invention, full-process intelligent detection of the drop-out fuse protection cover from image acquisition, feature recognition, defect classification, defect quantification to early warning output is realized.

The invention discloses an urban soil pollution degree detection method, particularly relates to the technical field of soil detection, and comprises a sampling area division stage, a sampling stage, a soil pollutant content analysis stage and a data processing stage. The sampling area division stage is used for performing detailed area division according to different use purposes of local soil, performing soil sampling by adopting a snakelike point distribution sampling method, and detecting types and corresponding contents of pollutants in the soil by adopting physical and chemical means; the soil pollution index and the comprehensive pollution degree are calculated according to the detected data, the pollution degree is divided into five levels, and finally the urban soil pollution degree is obtained.By detecting the content of the pollutants in the soil and calculating and dividing the soil pollution index, the urban soil pollution degree can be known more visually, and the urban soil pollution degree can be obtained more accurately. And the environmental awareness of people is improved.

The invention discloses an in-situ passivation method of sulfate reducing bacteria for remediation of cadmium and copper combined polluted soil, which belongs to the field of environmental science and engineering, and comprises the following steps: finding a sampling point with the highest pollution level through spatial analysis characteristic analysis by utilizing a Nemel comprehensive pollution index calculation method, and carrying out enrichment culture on indigenous sulfate reducing bacteria from the sampling point; and calculating the comprehensive pollution index and longitude and latitude information of each sampling point, drawing a comprehensive pollution index spatial distribution diagram of the research area by utilizing ArcGIS, determining the position of a high-value area and the corresponding sampling point, and carrying out indigenous SRB bacterial liquid enrichment and the like by utilizing a soil sample at the point. In-situ remediation is carried out on cadmium and copper combined pollution at the same time, and ecological risks and food chain risks of cadmium and copper are reduced. Compared with traditional physical and chemical remediation, the method has the remarkable advantages of low investment, low operation cost, environmental friendliness and the like.

The application discloses a pollution flashover disaster risk assessment method and system based on insulator contamination and wetting index. First, the operation time of each insulator on a power transmission line and the pollution area grade, historical meteorological data and pollution flashover data of a related area are collected. An insulator contamination index assessment model and a wetting index model are constructed by using environmental contamination concentration, corrected meteorological data and pollution flashover data. The above models are used to predict the contamination index and the wetting index, and then a predicted pollution flashover comprehensive index is calculated. According to a preset risk level threshold, a corresponding alarm signal is sent to early warn possible insulator contamination or pollution flashover events, so that the safety and stability of the power transmission line are effectively improved.

The invention relates to a metal pollution online monitoring method and system, electronic equipment, a storage medium and a computer program product. The method comprises the following steps: acquiring spectral data in a process cavity in a semiconductor process; calculating the SPE statistic of the spectral data according to a principal component analysis model, taking the spectral data as a pollution spectrum when the SPE statistic is judged to exceed a preset control limit, and entering a metal pollution analysis step which comprises the following steps: acquiring a closest reference spectrum based on a process time stage of the pollution spectrum, and calculating a difference spectrum between the pollution spectrum and the reference spectrum; calculating the pollution index of the to-be-detected metal based on the original spectral data and the differential spectrum; and matching the pollution index of the to-be-detected metal with a preset metal characteristic spectrum database, when a matching result meets a preset condition, determining that metal pollution exists in the process cavity, and outputting an alarm signal. According to the application, early warning and quick response to metal pollution can be realized, so that the process control level and the product yield of semiconductor manufacturing are improved.

This invention provides a river and lake water ecological governance system, belonging to the field of water body ecological governance technology, comprising: a data acquisition module: real-time monitoring of key data of preset types of river and lake water bodies based on preset sensors; an index analysis module: determining the pollution index based on monitoring data, and then determining the pollution level and main pollutants of the water body; a water quality early warning module: providing water quality early warning based on the pollution index and preset pollution index thresholds; a coefficient evaluation module: determining several pollution decomposition zones based on the water quality early warning results, and then obtaining and evaluating the decomposition coefficient of each pollution decomposition zone in conjunction with the pollution level of the water body; and a scheme determination module: determining the pollution decomposition scheme based on the evaluation results and the main pollutants, reducing the lag and human error in traditional methods, and effectively improving the ecological environment of river and lake water bodies.

The invention relates to the technical field of semiconductor equipment monitoring, in particular to a guide rail cleanliness monitoring system and method for semiconductor equipment. The system comprises a signal acquisition module, a signal processing module, a pollution identification module and an evaluation decision module. A signal processing module performs signal analysis on the collected electrostatic induction signals and acoustic emission signals, and performs event detection in combination with motion state information to obtain a characteristic event list and a pollution index vector; the pollution identification module performs space-time correlation analysis on the feature event list to obtain an internal wear source, and identifies an external settlement source in combination with a pollution index vector; applying an excitation signal to the external settlement source, and identifying a silent pollution layer according to a response result; the evaluation decision module generates a comprehensive evaluation result of the cleanliness state of the guide rail based on the internal wear source, the external settlement source and the silent pollution layer; according to the invention, the online monitoring of the cleanliness of the guide rail and the accurate identification of the pollution source are realized, and the operation reliability of semiconductor equipment is improved.

The invention relates to the technical field of intelligent detection, and discloses a cheese microbial pollution early warning method and system.The method comprises the steps that to-be-detected cheese is subjected to gradient heating, volatile organic compounds at different temperature stages are collected respectively, and gas samples of the to-be-detected cheese are obtained; detecting the gas sample by using a multi-parameter sensor array to obtain sensor response data of the cheese to be detected; according to the real-time response intensity and historical data reliability of the sensors in the multi-parameter sensor array, determining a weight coefficient set of the sensors during pollution index prediction; performing data fusion on the sensor response data based on the weight coefficient set to obtain a microbial pollution index of the cheese to be detected; when the microbial pollution index exceeds a preset pollution threshold value, generating a multi-stage microbial pollution report of the cheese to be detected based on the microbial pollution index; the cheese microbial pollution early warning efficiency can be improved.