Nonsingular terminal sliding mode control for the speed regulation of permanent magnet synchronous motor with parameter uncertainties

The drive performance of permanent magnet synchronous motor (PMSM) can be deteriorated due to various disturbances. In this paper, the problem of speed control for a PMSM system with parameter uncertainties is investigated. A new control algorithm based on nonsingular terminal sliding mode control (NTSMC) is proposed, where the controller is developed for speed regulation. Compared with conventional strategies, this new controller provides improved performance for speed regulation of PMSM when subject to parameter uncertainties, in that it achieves fast dynamic response and strong robustness. Simulation studies are conducted to verify the effectiveness of this proposed method

Continuity and changes in grandchild care and the risk of depression for Chinese grandparents: new evidence from CHARLS

ObjectivesAlthough studies have researched the mental effects of intergenerational care, little is known about the impact of transformations in caregiving intensity on depression. This study explores grand-parents’ depressive symptom outcomes in terms of changes over time in grandparental childcare, with considerations for subgroup differences.MethodUsing data from the 2015–2018 China Health and Retirement Longitudinal Study on grandparents aged 45 and older, we adopted generalized estimating equations to estimate the effects of seven category changes [(1) continued to provide high-intensity or (2) low-intensity care at both waves; (3) never provided care; (4) started caregiving; (5) ended caregiving; (6) provided less intensive care; and (7) provided more intensive care] over time in grandparental childcare on depressive symptoms among 17,701 grandparents with at least one grandchild, as well as how the impact varies by gender and urban/rural areas.ResultsGrandparents who decreased the intensity of care, stopped childcare, or offered continuous low-intensity care were associated with a lower level of depression compared with those providing no childcare. In addition, the benefit of continuous caregiving on mental health was especially noticeable in urban grandmothers.ConclusionProviding continuous low-intensity, decreased-intensity grandparenting and the cessation of caregiving were associated with a decreased level of depression for Chinese grandparents; however, there were complex interactions at play. Policies aimed at supporting grandparenting should consider caregiving intensity transitions relevant to gender and urban/rural residence

Engineering of Escherichia coli protein expression process development

It almost 30% protein drugs are expression by Escherichia coli, because of rapid growth and high production yield. We have developed E.coli base system for recombinant protein expression, scFv, Fab and vaccine. In this study we introduce example about process development for nutrient components selection. Shaker flasks were used for different nitrogen and carbon components screening by DoE. Seven media formulations for E. coli fermentation were used in this study. By changing nitrogen and carbon source ratio, product titer of target protein could be optimized, at least 1.4 folds increased. The best result from shaker flask was used in 250 mL parallel fermenter and pH, dissolved oxygen, feeding/induction strategy were evaluated. The processes from seed culture to harvest only require 64 hours. The optimized time was reduced to 32 hours. The result showed that both target protein expression and cell density value were comparable, but the total process time was significantly reduced by half Please click Additional Files below to see the full abstract