Quantitative evaluation of multi-process collaborative operation in steelmaking–continuous casting sections

The quantitative evaluation of multi-process collaborative operation is of great significance for the improvement of production planning and scheduling in steelmaking–continuous casting sections(SCCSs). However, this evaluation is difficult since it relies on an in-depth understanding of the operating mechanism of SCCSs, and few existing methods can be used to conduct the evaluation, due to the lack of full-scale consideration of the multiple factors related to the production operation. In this study, three quantitative models were developed, and the multiprocess collaborative operation level was evaluated through the laminar-flow operation degree, the process matching degree, and the scheduling strategy availability degree. Based on the evaluation models for the laminar-flow operation and process matching levels, this study investigated the production status of two steelmaking plants, plants A and B, based on actual production data. The average laminar-flow operation(process matching) degrees of SCCSs were obtained as 0.638(0.610) and 1.000(0.759) for plants A and B, respectively, for the period of April to July 2019. Then, a scheduling strategy based on the optimization of the furnace-caster coordinating mode was suggested for plant A. Simulation experiments showed higher availability than the greedy-based and manual strategies. After the proposed scheduling strategy was applied,the average process matching degree of the SCCS of plant A increased by 4.6% for the period of September to November 2019. The multi-process collaborative operation level was improved with fewer adjustments and interruptions in casting.

Modeling of LF refining process:a review

With the increasing demand for energy conservation and emission reduction,more attentions have been paid to the intelligentization,greenization and low carbonization during the transformation and upgrading of steelmaking plants.Ladle furnace(LF)refining is one of the key procedures in steelmaking process and has been widely used in steelmaking plants for its high equipment matching degree,low equipment investment and outstanding refining performance.According to the main tasks of LF refining process,the modeling methods of temperature prediction model,slag-making model,alloying model,argon blowing model and model of inclusions behavior were systematically reviewed,and the advantages and disadvantages of each modeling method were summarized.In addition,the technical framework for the future has also been proposed based on existing works,including classification of raw materials,graphic representation of knowledge,introduction,upgradation and management of device/equipment,customization of steelmaking,modeling of refining process,synergy of models,intelligentization of decision-making,automation of control,and digitization of processes and operations,aiming to provide a reference for the modeling and intelligent development of LF refining process.

Characteristics of and Risk Factors Associated with Self-Reported Sexual Repression among Internal Migrants in China: A Large-Scale Cross-Sectional Study

Objective:This large-scale cross-sectional study aims to identify the characteristics of and risk factors associated with sexual repression among internal migrants in China.Methods:Between August 2013 and August 2015,a total of 8,669 internal migrants from four major cities in China(Beijing,Shanghai,Chengdu,and Chongqing)voluntarily participated in our study.They were interviewed,and the data on their demographic information,occupation,and sexual activities were collected.The Chi-square test and multiple logistic regressions were conducted to identify significant associations.A stepwise method was adopted for the selection of variables.Results:There were 3,597(41.49%)males and 5,072(58.51%)females in total.A higher percentage of males reported that they felt sexual repression compared to females(14.43%vs.9.21%).After adjusting for other covariates,the consequence was showed that male migrants working for more than 5 days were more likely to report sexual repression(odds ratio[OR]=1.40,P<0.05).Living in a collective dormitory with others was also a risk factor for male migrants.The longer males spent with their partners,the less sexual repression occurred(OR=0.94,P<0.05).Similarly,agricultural household registration status and working for more than 5 days increased the risk for sexual repression among female migrants(OR=1.41 and OR=1.46,respectively,P<0.05).Frequent and constructive communication also protected females against sexual repression(P<0.05).Well-educated females experienced relatively less sexual repression when compared to their counterparts with less education(P<0.05).Conclusions:Sexual repression was significantly associated with a few demographic,occupational,and sexual risk factors.Meaningful differences have been identified between male and female migrants.More effective intervention programs such as safeguard measures and welfare policies should be designed and implemented for a majority of female migrants and for those with agricultural household registration status.