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To eliminate the angle deviation of magnetic encoder, this paper aims to propose a compensation method based on permanent magnet synchronous motor (PMSM) sensorless control. The paper also describes the experiments performed to verify the validity of this proposed method.

The proposed method uses PMSM sensorless control method to get high precision virtual angle value, and then get the deviation value between virtual position and magnetic angle which is used as compensation table. Oversampling linear interpolation tabulation method has been proposed to eliminate the noise signals. Finally, a magnetic encoder with precision (repeatability) 0.09° and unidirectional motion precision 0.03 is realized. The control system with an encoder running at 14,000 and 0.01 r/min showing high motion resolution is also realized.

Higher value of current in PMSM leads to a magnetic encoder with higher precision. When using oversampling linear interpolation to tabulate the compensation table, it is understood that more oversampling does not lead to a better result. Finally, validated by experiments, using eight intervals to calculate the mean value of angle deviation leads to the best result.

The angle deviation compensation method proposed in this paper has a great practical implication and a good commercial application. The method proposed in this paper could be effectively used to self-correct the magnetic encoder using arctangent method and also correct any rotary encoder sensor.

This paper originally proposes an adaptive correction method for a rotary encoder based on PMSM sensorless control. To eliminate the noise signals in an angle compensation table, over-sampling linear interpolation tabulation method has been proposed which also guarantees the precision of the compensation table.

The purpose of this paper is to investigate the corrosion behavior of X65 steel in the CO₂-saturated oil/water environment using mass loss method, potentiodynamic polarization technique and characterization of the corroded surface techniques.

The weight loss analysis, electrochemical study and surface investigation were carried out on X65 steel that had been immersed in the CO₂/oil/water corrosive medium to understand the corrosion behavior of gathering and transportation pipeline steel. The weight loss tests were carried out in a 3 L autoclave, and effects of water cut and temperature on the CO₂ corrosion rate of X65 steel were studied. Electrochemical studies were carried out in a three-electrode electrochemical cell with the test temperature was 60°C, and the CO₂ partial pressure was 1 atm by recording open circuit potential/time and potentiodynamic polarization characteristics. The surface and cross-sectional morphologies of corrosion product scales were characterized using scanning electron microscopy. The phases of corrosion product scales were investigated using x-ray diffraction.

The results showed that due to the wetting and adsorption of crude oil, the corrosion morphology of X65 steel changed under different water cuts. When the water cut of crude oil was 40-50 per cent, uniform corrosion occurred on the steel surface, accompanied by local pitting. While the water cut was 70-80 per cent, the resulting corrosion product scales were thick, loose and partial shedding caused platform corrosion. When the water cut was 90 per cent, the damaged area of platform corrosion was enlarged. Crude oil can hinder the corrosion scales from being dissolved by the corrosive medium, and change dimension and accumulation pattern of the crystal grain, thickness and structure of the corrosion scales. Under the corrosion inhibition effect of crude oil, the temperature sensitive point of X65 steel corrosion process moved to low temperature, appeared at about 50°C, lower corrosion rate interval was broadened and the corrosion resistance of X65 steel was enhanced.

The results can be helpful in selecting the applicable corrosion inhibitors and targeted anti-corrosion measures for CO₂-saturated oil/water corrosive environment.

This study aimed to facilitate a rapid evaluation of track service status and vehicle ride comfort based on car body acceleration. Consequently, a low-cost, data-driven approach was proposed for analyzing speed-related acceleration limits in metro systems.

A portable sensing terminal was developed to realize easy and efficient detection of car body acceleration. Further, field measurements were performed on a 51.95-km metro line. Data from 272 metro sections were tested as a case study, and a quantile regression method was proposed to fit the control limits of the car body acceleration at different speeds using the measured data.

First, the frequency statistics of the measured data in the speed-acceleration dimension indicated that the car body acceleration was primarily concentrated within the constant speed stage, particularly at speeds of 15.4, 18.3, and 20.9 m/s. Second, resampling was performed according to the probability density distribution of car body acceleration for different speed domains to achieve data balance. Finally, combined with the traditional linear relationship between speed and acceleration, the statistical relationships between the speed and car body acceleration under different quantiles were determined. We concluded the lateral/vertical quantiles of 0.8989/0.9895, 0.9942/0.997, and 0.9998/0.993 as being excellent, good, and qualified control limits, respectively, for the lateral and vertical acceleration of the car body. In addition, regression lines for the speed-related acceleration limits at other quantiles (0.5, 0.75, 2s, and 3s) were obtained.

The proposed method is expected to serve as a reference for further studies on speed-related acceleration limits in rail transit systems.

On the basis of corporate governance and agency cost theory, using the fifth sub-indicator of Fan et al. China Marketization Index as the regional investor protection index (IPI), the purpose of this paper is to explore the impact of equity incentives and regional investor protection on corporate payout policies and corporate performance.

This paper establishes ordinary least squares regression model to examine interactions between the effects of equity incentives and regional investor protection upon firms’ dividend payouts. In addition, the authors also explore whether the joint effects on payouts are altered in the presence of growth opportunities, and investigate the effects of interactions between equity incentives and regional investor protection on corporate performance.

The authors observe that firm managers appear to abuse equity incentives by increasing dividend payouts. However, regional investor protection can potentially restrain such behavior. The restraining effect depends on the firms’ growth opportunities, on the basis of which the effect on cash (stock) dividends is found to be weaker (stronger) in high-growth firms – and stronger (weaker) in low-growth firms. Further evidence indicates that the restraining effect of regional investor protection on selfish dividend-related behavior encouraged by equity incentives may also prove valuable in encouraging exploitation of these incentives so as to enhance corporate performance.

Since reforming investor protection laws and improving judicial quality are difficult and lengthy at a country level. Improving regional levels of investor protection, however, seems more feasible and effective. Through measures encouraging the development of intermediaries, increases in the number of lawyers – all of which seem likely to constrain behavior harmful to the interests of investors – the provincial administrations can reasonably expect to contribute toward improvements in the performance of firms and the development of the economy in their region. This paper provides encouragement to regional policy makers in China and in other developing countries.

This paper uses a regional index of investor protection to study the impact on corporate dividends and performance, in contrast with most previous studies, which have examined these issues at country or individual firm levels. The use of a regional-level investor IPI in this paper therefore fills a gap by coming in between the country- and firm-level indicators typically used in previous research, thus providing a new perspective on investor protection issues.

The purpose of this paper was to investigate the corrosion behaviour of API X65 pipeline steel in the simulated CO₂/oil/water emulsion using weight loss technique, potentiodynamic polarization technique and characterization of the corroded surface techniques.

The weight loss analysis, electrochemical study and surface investigation were carried out on API X65 pipeline steel that had been immersed in the CO₂/oil/water corrosive medium to understand the corrosion behaviour of gathering pipeline steel. The weight loss tests were carried out in a 3L autoclave, and effects of temperature, CO₂ partial pressure, water cut and flow velocity on the CO₂ corrosion rate of API X65 pipeline steel were studied. Electrochemical studies were carried out in a three-electrode electrochemical cell with the test temperature was 60°C, and the CO₂ partial pressure was 1 atm by recording open circuit potential/time and potentiodynamic polarization characteristics. The surface and cross-sectional morphologies of corrosion product scales were characterized using scanning electron microscopy. The phases of corrosion product scales were investigated using X-ray diffraction.

The results showed that water cut was the main controlling factor of API X65 steel corrosion under the conditions of CO₂/oil/water multiphase flow, and it had significant impact on corrosion morphology. In the case of higher water cut or pure water phase, general corrosion occurred on the steel surface. While water cut was below 70 per cent, corrosion morphology transformed into localized corrosion, crude oil decreased corrosion rate significantly and played a role of inhibitor. Crude oil hindered the corrosion scales from being dissolved by corrosive medium and changed dimension and accumulation pattern of the crystal grain, thickness and structure of the corrosion scales; thus, it influenced the corrosion rate. The primary corrosion product of API X65 steel was ferrous carbonate, which could act as a protective film at low water cut so that the corrosion rate can be reduced.

The results can be helpful in selecting the suitable corrosion inhibitors and targeted anti-corrosion measures for CO₂/oil/water corrosive environment.

The purpose of this paper is to study the corrosion behaviors of X70 steel under direct current (DC) interference at 0-1,200 A/m² in simulated soil solution.

The Tafel polarization curves of X70 steel under DC interference were tested using electrochemical method, the corrosion rate was calculated using weight-loss method and the change in steel surface was analyzed by optical microscopy.

The results showed that E-I polarization curves under 200-1,200 A/m² interference were linear; with an increase in the DC density, the corrosion potential of X70 steel shifted positively, solution pH after the weight-loss tests increased and corrosion rate increased linearly. A mathematical relationship between polarization resistance Rp and current density was established. Corrosion morphology indicated that pitting corrosion and crevice corrosion occurred on the X70 steel under DC interference in simulated soil solution.

All tests were conducted at a relative higher DC density (200-1,200 A/m²). The linear fitting method is proposed to fit data of Tafel polarization curves under DC interference. This study provides guidelines for safe operation of X70 steel pipelines.

When hydrogen evolution reaction occurs on a metal surface, on the one hand, the generated hydrogen atom may penetrate into the metal that causes the hydrogen embrittlement failure of materials; on the other hand, the hydrogen generation may increase the local pressure in the coating and cause coating blistering. The purpose of this study is to study the effect of NaCl concentration and pH on hydrogen evolution reaction of X60 steel.

A cathodic polarization curve 257E-2V vs OCP and EIS was obtained by conventional three-electrode system in different NaCl concentrations, 257E3.5 and pH. Second, various parameters such as hydrogen evolution, over-potential current–density polarization resistance and capacitance of double electric layer were obtained based on fitting of the experimental data. Finally, the reaction mechanism was determined by Tafel curves.

It was concluded that in different NaCl concentrations, diffusion layer induced by concentration polarization affects the diffusion process of H+ ions, which makes over-potential increase. Under great effect of concentration polarization, the reaction is different in acid and alkaline environments, and the dielectric layer shows the characteristic of meta-alkaline adsorption, which makes difference in mechanism.

This research not only has theoretical significance but also gains utilization prospect. Ultimately, this research could be applied to clear hydrogen evolution process and protect long-distance pipeline against delamination.

Counter-hedonic entertainment, characterized by evoking negative emotions in consumers, has emerged as one of the most popular and profitable forms of entertainment in Western countries. However, this entertainment type is not as popular in China as in Western countries. This study examines whether the free trial of counter-hedonic entertainment can promote the consumption of such entertainment and explores the moderating effect of contextual factors on this relationship.

This study investigates the promotional effectiveness of the free trial strategy on counter-hedonic entertainment through a quasi-experiment involving the broadcasting of a large-scale free counter-hedonic program. This study has analyzed the counter-hedonic consumption data from 31 major cities in China and employed econometric modeling to test the hypotheses.

Results show that the free trial of counter-hedonic entertainment can promote the sales of entertainment with similar categories. The follow-up moderation analyses show that the positive effect is amplified on days with less sunlight and for consumers with abundant (vs scarce) financial resources, thereby providing evidence to support the underlying drivers of the positive effect – the need for arousal and confidence frame. Meanwhile, the free trial of counter-hedonic entertainment also has a long-term effect after airing.

Based on existing research on consumers’ counter-hedonic consumption motivation, this study confirms the effectiveness and boundary conditions of the free trial strategy in promoting counter-hedonic entertainment consumption for the first time. The results also offer actionable insights for counter-hedonic entertainment marketers and practitioners.

The presence of alternating current (AC) causes serious damage on buried pipelines even when the off potential matches the −0.85 V/CSE criterion. The optimum cathodic protection potential (OCPP) is more accurate for cathodic protection. The paper aims to study how to get the optimum cathodic protection by electrochemical impedance spectroscopy (EIS) and the effects of AC on the OCPP.

This paper describes the application of EIS to investigate the OCPP of X70 steel in a soil simulating solution with different AC interferences.

The experimental results indicate that AC interference makes the OCPP decrease and the −0.85 V/CSE criterion is not reasonable when there is AC interference. When the AC voltage is less than 6 V, the OCPP is approximately −900 mV/SCE, and when AC voltage is more than 7 V, the OCPP is roughly −1,000 mV/SCE.

There have been some researches on the OCPP, and the paper is the first one to study the AC effects on the OCPP and found that the OCPP changed when there was AC interference.

The presence of alternating current (AC) causes serious damage on buried pipelines, even when the off potential meets the −0.85 V/CSE criterion. The optimum cathodic protection potential (OCPP) is more reliable for cathodic protection. The purpose of this paper is to study the effects of AC on the OCPP and, using electrochemical impedance spectroscopy (EIS), to investigate how to get the optimum cathodic protection.

The paper describes the application of EIS to investigate the OCPP of X70 steel in a soil simulating solution with different AC interferences.

The experimental results indicate that AC interference makes the OCPP decrease. It was determined that the −0.85 V/CSE criterion is not appropriate when there is AC interference. When the AC voltage was less than 6 V, the OCPP was approximately −900 mV/SCE, whereas when the AC voltage was more than 7 V, the OCPP was approximately −1,000 mV/SCE.

Although there have been previous research studies on the OCPP, this paper is the first to study the effects of AC interference on the OCPP and it has been confirmed that the OCPP changed when AC interference is present.