The technology for stepper drive that can achieve accurate motion in the hydraulic field has always been urgently needed in the industry. This paper proposes a hydraulic stepper drive based on five high speed on/off valves and two miniature plunger cylinders. The stepper drive discretizes the continuous flow medium into fixed small steps through the miniature plunger cylinder and realizes the state control of the drive through the logic action of the high speed on/off valve. This paper improves the current stepper drive and establishes a mathematical model to analyze the error of the drive and calculate the position of the actuator. In addition, through simulation research, the performance parameters such as the single-step step characteristic and pressure characteristic of the stepper drive are studied. The results show that, compared with the technology of current stepper drive, this stepper drive can effectively remove the “post step” phenomenon, greatly improve the stepper accuracy of the stepper drive, and have a more excellent performance.

Aim: To investigate clinical efficacy of transjugular intrahepatic portal shunt (TIPS) for the treatment of cirrhotic portal hypertension. Methods: 71 cases of patients with cirrhotic portal hypertension and esophageal and gastric variceal bleeding hospitalized from January 2014 to June 2017 were enrolled and treated with TIPS. The change of portal pressure and serum biochemical indexes before and after TIPS were compared, and re-hemorrhage rate, ascites incidence, complications, and survival rate were calculated. Results: 71 patients (male/female 47/24, aged 29-77 years, average 48.9 ± 9.8 years) with cirrhotic portal hypertension received TIPS. The success rate of TIPS was 93% (66/71). During 1-24 months (mean 12.5 ± 7 months) follow-up of 66 patients, 61 cases survived and 5 cases died. The portal pressure decreased significantly from 40.48 ± 3.15 cmH2O to 23.59 ± 4.41 cmH2O after TIPS (P < 0.05). During the follow-up, the incidence of hepatic encephalopathy was 12.1%, the incidence of re-hemorrhage was 18.2%, and there were 4 cases of stent dysfunction, with 1 case of bare stent and 3 cases of dual stent. Conclusion: TIPS is an effective procedure for the treatment of cirrhotic portal hypertension complications, since it can reduce portal pressure and significantly alleviate ascites. Liver function is impaired in short-term after TIPS, but TIPS has no significant effect on liver function in middle-term.

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“The very sun irradiates their gorgeous palace, but never bypasses our tatty hut: sunshine is equal.” -Shakespeare Equity is the common desire of all people in this world, and it is also a silently tacit agreement between countries and the strategic balance they want to pursue. However, the recent asteroid mining craze seems to be quietly influencing the existing equity degree around the globe. We developed the World Resource Equity Assessment Model (WREAM) and other related models in order to measure the equity degree of the earth as a regional system and to propose policies to regulate it.In this paper, we reviewed the relevant literature, then collected the required data and performed data pre-processing. Next, for the problem we faced, we developed a model that can assess the degree of equity of any regional system. In this model, we combined subjective hierarchical analysis with objective entropy weighting to obtain the weights of each indicator, and then calculated the IP and OP (Input and Output) for each country using the TOPSIS integrated evaluation method. By introducing the Pearson correlation linear coefficients fitted with the one-dimensional linear regression, the degree of global equity was judged by judging the magnitude of the one-dimensional linear regression coefficients. Then, we applied this World Resource Equity Assessment Model to 10 countries. we made predictions for possible future visions of asteroid mining for pre-policy interventions and post-policy interventions.