Online Capacitor Voltage Transformer Measurement Error State Evaluation Method Based on In-Phase Relationship and Abnormal Point Detection

The assessment of the measurement error status of online Capacitor Voltage Transformers (CVT) within the power grid is of profound significance to the equitable trade of electric energy and the secure operation of the power grid. This paper advances an online CVT error state evaluation method, anchored in the in-phase relationship and outlier detection. Initially, this method leverages the in-phase relationship to obviate the influence of primary side fluctuations in the grid on assessment accuracy. Subsequently, Principal Component Analysis (PCA) is employed to meticulously disentangle the error change information inherent in the CVT from the measured values and to compute statistics that delineate the error state. Finally, the Local Outlier Factor (LOF) is deployed to discern outliers in the statistics, with thresholds serving to appraise the CVT error state. Experimental results incontrovertibly demonstrate the efficacy of this method, showcasing its prowess in effecting online tracking of CVT error changes and conducting error state assessments. The discernible enhancements in reliability, accuracy, and sensitivity are manifest, with the assessment accuracy reaching an exemplary 0.01%.

Determination of gross α and β activities in Zouma River based on online HPGe gamma measurement system

This paper describes a low-cost and fast method to evaluate gross α and β^(-) radioactivities in natural water based on an online high-purity germanium detector gamma measurement system.The major gamma activities in natural water are provided by natural and artificial radionuclides such as ^(40) K,^(137)Cs,and radionuclides belonging to ^(238)U and ^(232)Th series.The main a emitters related to gamma emissions in natural water are ^(224)Ra(240.98 keV)and ^(226)Ra(186.21 keV),and the β^(-) emitters are ^(40) K(1460.85 keV),^(214)Bi(609.31 keV),^(208)Tl(583.19 keV),and ^(214)Pb(351.93 keV).The formula for gross α and β^(-) activity concentration is based on these radionuclides,and the short half-life decay products are considered in the calculation.The detection efficiency of the device across energy region(0–3 MeV)is obtained through Monte Carlo simulation,and a calibration experiment is conducted to verify the simulation results.Gamma radioactivity is measured continuously for 114 d in Pixian County and Dongfeng Canal located in the Zouma River,Chengdu,Sichuan Province,China.A comparison of the calculation results and monitoring data from the Sichuan Management and Monitoring Center Station of Radioactive Environment indicates that the percentage and absolute error of a activity concentration is lower than 53%and 0.02 Bq/L,respectively,and that of β-activity concentration is lower than 33.2%and 0.016 Bq/L,respectively.The method can rapidly determine gross α and β^(-) activity concentrations in natural water online.

Online dynamic measurement of saturation-capillary pressure relation in sandy medium under water level fluctuation

An online dynamic method based on electrical conductivity probe, tensiometer and datataker was presented to measure saturation-capillary pressure （S-p） relation in water-light nonaqueous phase liquid （LNAPL） two-phase sandy medium under water level fluctuation. Three-electrode electrical conductivity probe （ECP） was used to measure water saturation. Hydrophobic tensiometer was obtained by spraying waterproof material to the ceramic cup of commercially available hydrophilic tensiometer. A couple of hydrophilic tensiometer and hydrophobic tensiometer were used to measure pore water pressure and pore LNAPL pressure of the sandy medium, respectively. All the signals from ECP and tensiometer were collected by a data taker connected with a computer. The results show that this method can finish the measurement of S-R relation of a complete drainage or imbibition process in less than 60 min. It is much more timesaving compared with 10-40 d of traditional methods. Two cycles of water level fluctuation were produced, and four saturation-capillary pressure relations including two stable residual LNAPL saturations of the sandy medium were obtained during in 350 h. The results show that this method has a good durable performance and feasibility in the porous medium with complicated multiphase flow. Although further studies are needed on the signal stability and accuracy drift of the ECP, this online dynamic method can be used successfully in the rapid characterization of a LNAPL migration in porous media.

Roller Profile Online Measurement Based on Ultrasonic Circulation Pulse-echo Technology

In order to meet the high precision requirement of wide steel strip in industry field, a novel online measurement of roller profile based on sonic circulation and pulse-echo technology was introduced. All kinds of the factors influencing the accuracy of roller profile online measurement were analyzed in detail and error compensation analysis of system was accordingly presented. In order to reduce count error, field program gate array(FPGA) was introduced and a highprecision data acquisition system was designed based on digital phase-shift technology. Experiments indicate that the standard deviation of measure data was 7.27 μm, which showed the feasibility and validity of the proposed method, and realized the roll profile measurement with high precision.

Experimental study by online measurement of the precipitation of nickel hydroxide: Effects of operating conditions

The objective of this work is using the online measurement method to study the process of precipitation of nickel hydroxide in a single-feed semi-batch stirred reactor with an internal diameter ofD = 240mm. The effects of impeller speed, impeller type, impeller diameter and feed location on the mean particle size d43 and particle size distribution （PSD） were investigated, d43 and PSD were measured online using a Malvern Insitec Liquid Pro- cess Sizer every 20 s. It was found that d43 varied between 13 kwh and 26 lain under different operating conditions, and it decreased with increasing impeller diameter. When feeding at the off-bottom distance of D/2 under lower impeller speeds, d43 was significantly smaller than that at D/3. PSDs were slightly influenced by operating conditions.

A Flexible Calibration Method of Laser Light-Sectioning System for Online 3D Measurement

A flexible calibration method based on a front-coated flat mirror is proposed for a laser light-sectioning three-dimensional(3D)measurement system. Since the calibration target and its mirror image are spatially separated and can be recorded in an image by a camera,the proposed method requires only a single composite image that contains a non-planar checkerboard pattern,a laser strip projected on the target and their mirror images to complete the calibration of the camera and the laser plane in one step. Levenberg-Marquardt(LM)algorithm is used to optimize the system parameters,and the measurement accuracy and speed are improved to enable online 3D inspection. Static and dynamic online 3D measurements are carried out on a cup and a triple stepped shaft,respectively,to validate the proposed method. The shaft has two steps with the depth of(0.5±0.01)mm and(2±0.01)mm to be measured online when the shaft is rotated and translated at the same time. The measurement results can be output at a frequency of 7 to 11 readings per second with standard deviations of 0.040 mm and 0.051 mm. The experimental results verify the effectiveness and flexibility of the proposed method.

Development of Online Machining and Measurement System in Die and Mold Manufacturing： Concept and Fundamental Experiments

The corrective machining to compensate the resulting errors is usually tried at plural times based on the trial-and-error process when the machining is realized in die and mold manufacturing. This corrective machining has an influence on accuracy and efficiency and is an important factor. The measurement system for measuring the forms of die and mold at all times is essential in order to machine the die and mold with high accuracy and efficiency. However, the problems of management and operation errors are found in compensating process of die and mold machining. In this paper, an online machining and measurement system in die and mold manufacturing is developed in order to overcome these problems. In this online system, 2-axis control system is added to a surface roughness measuring instrument, and both NC machining program and measured data are linked and controlled using a same computer. Therefore, the machining and measurement can be recognized for consistent process, and can be realized on the machine. This system has the advantages such as the high accuracy, low-price, and online convenience and so on. The possibility of practical use of this online system was investigated by fundamental experiments.

Early warning method for thermal runaway of lithium-ion batteries under thermal abuse condition based on online electrochemical impedance monitoring

Early warning of thermal runaway(TR)of lithium-ion batteries(LIBs)is a significant challenge in current application scenarios.Timely and effective TR early warning technology is urgently required considering the current fire safety situation of LIBs.In this work,we report an early warning method of TR with online electrochemical impedance spectroscopy(EIS)monitoring,which overcomes the shortcomings of warning methods based on traditional signals such as temperature,gas,and pressure with obvious delay and high cost.With in-situ data acquisition through accelerating rate calorimeter(ARC)-EIS test,the crucial features of TR were extracted using the RReliefF algorithm.TR mechanisms corresponding to the features at specific frequencies were analyzed.Finally,a three-level warning strategy for single battery,series module,and parallel module was formulated,which can successfully send out an early warning signal ahead of the self-heating temperature of battery under thermal abuse condition.The technology can provide a reliable basis for the timely intervention of battery thermal management and fire protection systems and is expected to be applied to electric vehicles and energy storage devices to realize early warning and improve battery safety.

ONLINE GRINDING WHEEL WEAR COMPENSATION BY IMAGE BASED MEASURING TECHNIQUES

Automatic compensation of grinding wheel wear in dry grinding is accomplished by an image based online measurement method. A kind of PC-based charge-coupled device image recognition system is schemed out, which detects the topography changes of the grinding wheel surface. Profile data, which corresponds to the wear and the topography, is measured by using a digital image processing method. The grinding wheel wear is evalualed by analyzing the position deviation of the grinding wheel edge. The online wear compensation is achieved according to the measure results. The precise detection and automatic compensation system is integrated into an open structure CNC curve grinding machine. A practical application is carried out to fulfil the precision curve grinding. The experimental results confirm the benefits of the proposed techniques, and the online detection accuracy is less than 5 um. The grinding machine provides higher precision according to the in-process grinding wheel error compensation.

On the Advantages and Disadvantages of Online English Teaching and Improvement Measures

With the rapid development and wide application of the network,many universities conform to the development of thetimes and actively carry out online English teaching.Online teaching is an important choice for higher education in modern times.It takes the Internet as the transmission system and uses the characteristics and resources of the network to create a meaningfullearning environment different from traditional teaching,which is beneficial to students’learning.After decades of development,ithas become a good teaching mode in addition to the traditional classroom teaching model.However,because its development inChina is still in its infancy,there are inevitably some shortcomings.This article discusses the advantages and disadvantages of on-line English teaching and puts forward some improvement measures.

A Technology for Online Parameter Identification of Permanent Magnet Synchronous Motor

Accuracy of the motor parameters is important in realizing high performance control of permanent magnet synchronous motor(PMSM).However,the inductance and resistance of motor winding vary with the change of temperature,rotor position and current frequency.In this paper,a technology based on circuit model is introduced for realizing online identification of the parameter of PMSM.In the proposed method,a set of nonlinear equations containing the parameters to be identified is established.Considering that it is very difficult to obtain the analytical solution of a nonlinear system of equations,Newton iterative method is used for solving the equations.Both the simulation and testing results confirm the effectiveness of the method presented.

Source apportionment of PM_(2.5)using PMF combined online bulk and single-particle measurements:Contribution of fireworks and biomass burning

Fireworks(FW)could significantly worsen air quality in short term during celebrations.Due to similar tracers with biomass burning(BB),the fast and precise qualification of FW and BB is still challenging.In this study,online bulk and single-particle measurements were combined to investigate the contributions of FW and BB to the overall mass concentrations of PM_(2.5)and specific chemical species by positive matrix factorization(PMF)during the Chinese New Year in Hong Kong in February 2013.With combined information,fresh/aged FW(abundant ^(140)K_(2)NO_(3)^(+)and ^(213)K_(3)SO_(4)^(+)formed from ^(113)K_(2)Cl^(+)discharged by fresh FW)can be extracted from the fresh/aged BB sources,in addition to the Second Aerosol,Vehicles+Road Dust,and Sea Salt factors.The contributions of FW and BB were investigated during three high particle matter episodes influenced by the pollution transported from the Pearl River Delta region.The fresh BB/FW contributed 39.2%and 19.6%to PM_(2.5)during the Lunar Chinese New Year case.However,the contributions of aged FW/BB enhanced in the last two episodes due to the aging process,evidenced by high contributions from secondary aerosols.Generally,the fresh BB/FW showed more significant contributions to nitrate(35.1%and15.0%,respectively)compared with sulfate(25.1%and 5.9%,respectively)and OC(14.8%and11.1%,respectively)on average.In comparison,the aged FW contributed more to sulfate(13.4%).Overall,combining online bulk and single-particle measurement data can combine both instruments’advantages and provide a new perspective for applying source apportionment of aerosols using PMF.

Effect of introducing an online system on the follow-up of elbow arthroplasty

AIM To evaluate the effect of introducing a structured online follow-up system on the response rate.METHODS Since June 2015 we have set up an electronic followup system for prosthesis in orthopedic patients. This system allows prospective data gathering using both online and paper questionnaires. In the past all patients received questionnaires on paper. This study includes only patients who received elbow arthroplasty. Response rates before and after introduction of the online database were compared. After the implementation,completeness of the questionnaires was compared between paper and digital versions. For both comparisons Fisher's Exact tests were used.RESULTS A total of 233 patients were included in the study. With the introduction of this online follow-up system,the overall response rate increased from 49.8% to 91.6%(P < 0.01). The response rate of 92.0% in the paper group was comparable to 90.7% in the online group(P > 0.05).Paper questionnaires had a completeness of 54.4%,which was lower compared to the online questionnaires where we reached full completeness(P < 0.01). Furthermore,non-responders proved to be younger with a mean age of 52 years compared to a mean age 62 years of responders(P < 0.05).CONCLUSION The use of a structured online follow-up system increased the response rate. Moreover,online questionnaires are more complete than paper questionnaires.

Malicious Activities Prediction Over Online Social Networking Using Ensemble Model

With the vast advancements in Information Technology,the emergence of Online Social Networking(OSN)has also hit its peak and captured the atten-tion of the young generation people.The clone intends to replicate the users and inject massive malicious activities that pose a crucial security threat to the original user.However,the attackers also target this height of OSN utilization,explicitly creating the clones of the user’s account.Various clone detection mechanisms are designed based on social-network activities.For instance,monitoring the occur-rence of clone edges is done to restrict the generation of clone activities.However,this assumption is unsuitable for a real-time environment and works optimally during the simulation process.This research concentrates on modeling and effi-cient clone prediction and avoidance methods to help the social network activists and the victims enhance the clone prediction accuracy.This model does not rely on assumptions.Here,an ensemble Adaptive Random Subspace is used for clas-sifying the clone victims with k-Nearest Neighbour(k-NN)as a base classifier.The weighted clone nodes are analysed using the weighted graph theory concept based on the classified results.When the weighted node’s threshold value is high-er,the trust establishment is terminated,and the clones are ranked and sorted in the higher place for termination.Thus,the victims are alert to the clone propaga-tion over the online social networking end,and the validation is done using the MATLAB 2020a simulation environment.The model shows a better trade-off than existing approaches like Random Forest(RF),Naïve Bayes(NB),and the standard graph model.Various performance metrics like True Positive Rate(TPR),False Alarm Rate(FAR),Recall,Precision,F-measure,and ROC and run time analysis are evaluated to show the significance of the model.

Recommendations for Using Wiki in Online Group Projects in Engineering Education

Although Web 2.0 tools like blogs and wikis have been used for supporting collaborative learning in higher education, there are not many reports about implementation of that resource on engineering in Brazil. In this way, the main purpose of this research is to use a wiki platform for online activities and evaluate how students collaborate with each other in online tasks. It was investigated how collaboration can be measured on wiki platform During four-week online activities, 40 students of Civil Engineering course were monitored on Wikispaces~ platform. All students＇ actions were analyzed and classified as low, medium, or high level of collaboration. The data were collected through the statistical reports of Wikispaces~ and Google Analytics platforms. It computed 336 students＇ actions： 16.67% as high level, 45.24% as medium, and 38.10% as low. During informal interview, most of students （70%） related that wiki was a nice tool for collaboration work. The results indicated that wiki platform is an important way to develop innovative activities and tasks for the purpose of improving engineers＇ abilities and skills such as： writing communication, organization, collaboration, and critical thinking development.

Non-intelligence Factors in Online English Learning

In the process of online English learning,learning efficiency is influenced by various non-intelligence factors.Non-intelligence factors include learning motivation,self-efficacy,cultural background knowledge and online learning strategies which play crucial roles in online English learning.This paper analyses the non-intelligence factors affecting students'online English learning and put forwards some measures to enhance online English learning.

基于中红外吸收光谱的痕量水汽在线测量

痕量水汽检测在半导体芯片制造、大气模型研究、高纯气体制备等方面发挥重要作用。针对痕量水汽浓度的精确、快速测量的需求,提出基于5020 nm中红外激光器的可调谐半导体激光吸收光谱(TDLAS)技术对高纯氮气中的痕量水汽进行实时在线测量的方案。气体在中红外波段具有高选择性和吸收能力的特点,在此波段进行痕量水汽检测具有选择性好、灵敏度高、响应时间短等优点。根据HITRAN数据库中光谱参数对水汽吸收谱线进行仿真,仿真结果表明H2O在5020.36 nm处有强吸收,且无其他气体干扰,选取该谱线对高纯氮气中的水汽吸收进行研究。选用5020 nm中心波长的带间级联激光器(ICL)作为光源搭建TDLAS实验系统。激光器输出激光分为两路,一路作为参考光路,用于获得吸收池外的背景水汽吸收,另一路为测量光路,通过Herriott吸收池获得待测气体中的水汽吸收,吸收池内光程L=10 m。探测器将接收到的光信号转换为电信号,经放大电路放大后被采集并传输到计算机,采样频率为25 MHz。分别对参考、测量光路信号进行基线拟合和Voigt线型拟合,得到水汽的吸光度曲线和积分吸光度,通过计算扣除测量光路中的背景水汽吸收,得到高纯氮气中的痕量水汽浓度。将上述反演过程的算法嵌入软件平台,对采集的透射光强数据直接进行反演处理,实时得到吸收池内高纯氮气中的水汽浓度值,响应时间为12 s。待水汽浓度值稳定后,取30次测量结果的平均值作为各批次高纯氮气水汽浓度的实验结果。实验结果表明,测量得到的各批次高纯氮气的痕量水汽浓度与国家标准要求的高纯氮气中水汽浓度之间的偏差小于±5%,最大偏差为-3.04%,对实验结果进行误差分析,计算得到水汽体积分数的不确定度最大为0.159×10^(-6)。该实验装置可以在中红外波段对高纯气体中痕量水汽浓度进行准确、可靠的在线测量,为中红外波段进行痕量气体在线监测提供一种切实可行的方案。

Online measurement of alkalinity in anaerobic co-digestion using linear regression method

Alkalinity is a reliable indicator of process stability in anaerobic digestion system.Total alkalinity(TA)and partial alkalinity(PA)are usually monitored offline as indicators for the status of anaerobic digestion process.In order to online monitor TA and PA,the linear regression method was used as estimator to predict alkalinity via software sensor method.Parameters,namely,pH,oxidation and reduction potential(ORP),and electrical conductivity(EC),were used as input variables.EC was the most significant parameter with TA and PA.Multiple linear regression(MLR)models and simple linear regression models with EC were constructed to predict TA and PA in anaerobic co-digestion system.On the basis of the evaluation of prediction accuracy,the applications of linear regression models were better for monitoring PA than TA.MLR models provided higher accuracy for alkalinity prediction than simple linear regression models.The two MLR models based on single-phase anaerobic digestion system were also feasible to predict TA in anaerobic co-digestion systems.However,the accuracy of these models should be improved by calibrating for broad applications of linear regression method in online alkalinity measurement.

Online Power System Voltage Stability Index for LCC HVDC Using Local Measurements

This paper proposes an online power system voltage stability index(PVSI Online)that quantifies power system voltage stability in real time between an AC network and LCC HVDC using only local measurements.Previous methods relied on using telecommunications to inform a change in a predetermined AC network model.The proposed method uses local measurements of voltage and current from the HVDC using a newly developed,numerically robust technique called Moving Window Covariance to detect a change in the AC network in real time.These network parameters are fed to a newly devised index that accurately models and captures the dynamics of the interaction between an LCC HVDC and AC network.The index is used to quantify stability,but also to advise network operation.In an onset of instability due to network degradation,the proposed index can provide a power order value for the HVDC to restore stability.All as a self-contained module that can be implemented within a HVDC scheme.

Feedback regulation system for spraying parameters based on online droplet mass deposit measurements

In order to effectively optimize and regulate spraying parameters based on actual spraying performance and improve pesticide utilization rate,in this research,a feedback regulation system for the regulation of spraying parameters was designed based on droplet mass deposit online measurement.The system consisted of an online droplet mass deposit measurement module,wireless transmission module,decision module,and spraying parameters regulation module.First,the droplet mass deposits on the sampling points were measured.Based on the deviation between the measured and expected droplet mass,the expected spraying parameters were determined by the decision module.The spraying parameter was regulated to the expected value by regulating the pulse duty cycle on the pump motor using a micro control unit and a relay.Evaluation tests were conducted indoors using an indoor spraying platform and outdoors using an unmanned aerial vehicle.The results showed that the relative errors between the expected and measured droplet mass deposit after regulation were 6.84%and 11.48%for the indoor and outdoor tests,respectively.Therefore,an optimal spraying performance was observed after regulation.This research provided an experimental platform to quickly optimize spraying parameters and also provided technical references for precision spraying.