在两级式AC-DC变换器中,前级功率因数校正(power factor correction,PFC)固有的瞬时功率波动特性会造成母线电压存在二倍频纹波,影响后级CLLLC谐振变换器的输出电压质量。针对以上问题,该文提出了基于二阶广义积分(second order general...在两级式AC-DC变换器中,前级功率因数校正(power factor correction,PFC)固有的瞬时功率波动特性会造成母线电压存在二倍频纹波,影响后级CLLLC谐振变换器的输出电压质量。针对以上问题,该文提出了基于二阶广义积分(second order generalized integral,SOGI)的可变增益母线电压纹波前馈控制方法。采用SOGI提取母线电压纹波信息,基于品质因数Q与电压增益的关系和母线电压纹波对归一化频率的影响,解析了母线电压纹波对CLLLC谐振变换器输出电压的影响机理,得到Q值与前馈增益系数Ka的关系,采用仿真寻优加数据拟合的方法得到前馈可变增益系数曲线。仿真和实验结果表明,相比于无前馈控制,所提控制方法对CLLLC谐振变换器的输出电压纹波具有较好的抑制效果,输出电压纹波降低了72%,验证了所提算法的有效性。展开更多
Background: ACS is a leading cause of mortality worldwide, but it is unknown whether the advanced age of patients constitutes a prognostic factor. Objective: The present study compared the burden of risk factors and t...Background: ACS is a leading cause of mortality worldwide, but it is unknown whether the advanced age of patients constitutes a prognostic factor. Objective: The present study compared the burden of risk factors and the prognosis of ACS in older and younger patients in order to improve their management. Methods. A retrospective analysis of a series of ACS patients admitted from January to December 2022 to intensive care unit of the cardiology department at the South Francilian Hospital Center. Results: The files of 551 patients including 60 elderly subjects (10.9%) were analyzed. Average age was 81.7 ± 6.1 years for the elderly, 54.5 ± 11.9 years for the younger patients. Men predominated in both age categories (p = 0.014) and were older than women (59.2 ± 14.3 vs 53.1 ± 13.2 years;p = 0.014). Obesity (p = 0.007), smoking (p = 0.002) and dyslipidemia (p = 0.022) were the cardiovascular risk factors found more in elderly patients, hypertension (p < 0.001) and diabetes (p < 0.001) in the youngest. NSTEMI (66.3%) predominated in both the elderly (55.0%) and the younger (60.8%) subjects. Treatment consisted of immediate angioplasty in 66.1%, including 61.7% elderly subjects and 66.6% younger subjects (p = 0.224). Death was significantly associated with the severity of coronary lesions (p < 0.001) and chronic renal failure (p = 0.006), with no significant influence of age. Conclusion: The proportion of elderly subjects with ACS is not negligible. Comorbidities increase the prognosis, without age per se being associated with death.展开更多
Seed priming is an effective seed pretreatment technology that enhances germination and overall crop performance by optimizing seed hydration and metabolic processes before planting.Seed quality is a critical determin...Seed priming is an effective seed pretreatment technology that enhances germination and overall crop performance by optimizing seed hydration and metabolic processes before planting.Seed quality is a critical determinant of cotton(Gossypium hirsutum)crop performance,influencing germination,plant vigor,and yield.This study evaluates the effects of seed priming with potassium salts(1%and 2%KCl and K2SO4)on germination,morphological traits,and Cry1Ac gene expression in three Bt cotton cultivars(IUB-2013,NIAB-878B,FH-142)as Cry1Ac enhance the pest resistance in Bt cotton and reduce the plant’s dependence on chemical insecticides.Seeds were primed for six hours,air-dried,and sown in the field.Germination rates,plant height,number of bolls per plant,boll weight,seed cotton yield,and ginning outturn(GOT)were assessed at crop maturity.Cry1Ac gene expression was quantified to explore the influence of priming treatments on transgene activity.Results demonstrated that 1%K2SO4 priming significantly enhanced germination and yield-related traits,with Cry1Ac expression peaking in the IUB-2013 cultivar under 1%K2SO4 treatment.These findings suggest that potassium-based halopriming improves cotton seedling establishment and Bt gene expression.This study addresses the critical gaps in understanding the effects of seed halopriming on morphological traits,germination,and expression of the Cry1Ac gene in Bt cotton while providing a novel eco-friendly and cost-effective halopriming approach,offering the potential to improve cotton production.展开更多
This study addresses the challenges posed by dispersive soil in various engineering fields,including hydraulic and agricultural engineering,by exploring the effects of physical adsorption on soil modification.The prim...This study addresses the challenges posed by dispersive soil in various engineering fields,including hydraulic and agricultural engineering,by exploring the effects of physical adsorption on soil modification.The primary objective is to identify an environmentally friendly stabilizer that can alleviate cracking and erosion resulting from soil dispersivity.Activated carbon(AC),known for its porous nature,was examined for its potential to enhance soil strength and erosion resistance.The charge neutralization process was evaluated by monitoring pH and conductivity,in addition to a comprehensive analysis of microscopic and mineral properties.The results show that high sodium levels or low clay contents result in the dispersive nature of soil in water.However,the incorporation of AC can transform such soil into a non-dispersive state.Moreover,both soil strength and erosion resistance exhibited enhancements with increasing AC content and curing duration.The incorporation of AC resulted in a maximum 5.6-fold increase in unconfined compressive strength and a 1.8-fold increase in tensile strength for dispersive soil.Notably,a significant correlation was observed during the curing phase among soil dispersivity,mechanical properties,and pH values.Microscopic analyses revealed that the porous structure of AC facilitated a filling effect and enhanced adsorption capacity,which contributed to improved soil characteristics and reduced dispersivity.The release of hydrogen ions and the formation of aggregates promote water stability.Validation tests conducted on dispersive soil from northern Shaanxi demonstrated the efficacy of physical adsorption using AC as a viable method for modifying dispersive soil in the water conservancy hub.展开更多
The rapid development of new energy power generation technology and the transformation of power electronics in the core equipment of source-grid-load drives the power system towards the“double-high”development patte...The rapid development of new energy power generation technology and the transformation of power electronics in the core equipment of source-grid-load drives the power system towards the“double-high”development pattern of“high proportion of renewable energy”and“high proportion of power electronic equipment”.To enhance the transient performance of AC/DC hybrid microgrid(HMG)in the context of“double-high,”aπtype virtual synchronous generator(π-VSG)control strategy is applied to bidirectional interface converter(BIC)to address the issues of lacking inertia and poor disturbance immunity caused by the high penetration rate of power electronic equipment and new energy.Firstly,the virtual synchronous generator mechanical motion equations and virtual capacitance equations are used to introduce the virtual inertia control equations that consider the transient performance of HMG;based on the equations,theπ-type equivalent control model of the BIC is established.Next,the inertia power is actively transferred through the BIC according to the load fluctuation to compensate for the system’s inertia deficit.Secondly,theπ-VSG control utilizes small-signal analysis to investigate howthe fundamental parameters affect the overall stability of the HMG and incorporates power step response curves to reveal the relationship between the control’s virtual parameters and transient performance.Finally,the PSCAD/EMTDC simulation results show that theπ-VSG control effectively improves the immunity of AC frequency and DC voltage in the HMG system under the load fluctuation condition,increases the stability of the HMG system and satisfies the power-sharing control objective between the AC and DC subgrids.展开更多
文摘Background: ACS is a leading cause of mortality worldwide, but it is unknown whether the advanced age of patients constitutes a prognostic factor. Objective: The present study compared the burden of risk factors and the prognosis of ACS in older and younger patients in order to improve their management. Methods. A retrospective analysis of a series of ACS patients admitted from January to December 2022 to intensive care unit of the cardiology department at the South Francilian Hospital Center. Results: The files of 551 patients including 60 elderly subjects (10.9%) were analyzed. Average age was 81.7 ± 6.1 years for the elderly, 54.5 ± 11.9 years for the younger patients. Men predominated in both age categories (p = 0.014) and were older than women (59.2 ± 14.3 vs 53.1 ± 13.2 years;p = 0.014). Obesity (p = 0.007), smoking (p = 0.002) and dyslipidemia (p = 0.022) were the cardiovascular risk factors found more in elderly patients, hypertension (p < 0.001) and diabetes (p < 0.001) in the youngest. NSTEMI (66.3%) predominated in both the elderly (55.0%) and the younger (60.8%) subjects. Treatment consisted of immediate angioplasty in 66.1%, including 61.7% elderly subjects and 66.6% younger subjects (p = 0.224). Death was significantly associated with the severity of coronary lesions (p < 0.001) and chronic renal failure (p = 0.006), with no significant influence of age. Conclusion: The proportion of elderly subjects with ACS is not negligible. Comorbidities increase the prognosis, without age per se being associated with death.
基金National Natural Science Foundation of China(3216045632360474+2 种基金32360486)grants from the Provincial Basic Research Program(Natural Science)([2020]1Z018)Provincial Key Technology R&D Program([2021]YiBan272).
文摘Seed priming is an effective seed pretreatment technology that enhances germination and overall crop performance by optimizing seed hydration and metabolic processes before planting.Seed quality is a critical determinant of cotton(Gossypium hirsutum)crop performance,influencing germination,plant vigor,and yield.This study evaluates the effects of seed priming with potassium salts(1%and 2%KCl and K2SO4)on germination,morphological traits,and Cry1Ac gene expression in three Bt cotton cultivars(IUB-2013,NIAB-878B,FH-142)as Cry1Ac enhance the pest resistance in Bt cotton and reduce the plant’s dependence on chemical insecticides.Seeds were primed for six hours,air-dried,and sown in the field.Germination rates,plant height,number of bolls per plant,boll weight,seed cotton yield,and ginning outturn(GOT)were assessed at crop maturity.Cry1Ac gene expression was quantified to explore the influence of priming treatments on transgene activity.Results demonstrated that 1%K2SO4 priming significantly enhanced germination and yield-related traits,with Cry1Ac expression peaking in the IUB-2013 cultivar under 1%K2SO4 treatment.These findings suggest that potassium-based halopriming improves cotton seedling establishment and Bt gene expression.This study addresses the critical gaps in understanding the effects of seed halopriming on morphological traits,germination,and expression of the Cry1Ac gene in Bt cotton while providing a novel eco-friendly and cost-effective halopriming approach,offering the potential to improve cotton production.
基金financially supported by the National Postdoctoral Program for Innovative Talents(Grant No.BX20200287)the National Natural Science Foundation of China(Grant Nos.52079116 and 52378322).
文摘This study addresses the challenges posed by dispersive soil in various engineering fields,including hydraulic and agricultural engineering,by exploring the effects of physical adsorption on soil modification.The primary objective is to identify an environmentally friendly stabilizer that can alleviate cracking and erosion resulting from soil dispersivity.Activated carbon(AC),known for its porous nature,was examined for its potential to enhance soil strength and erosion resistance.The charge neutralization process was evaluated by monitoring pH and conductivity,in addition to a comprehensive analysis of microscopic and mineral properties.The results show that high sodium levels or low clay contents result in the dispersive nature of soil in water.However,the incorporation of AC can transform such soil into a non-dispersive state.Moreover,both soil strength and erosion resistance exhibited enhancements with increasing AC content and curing duration.The incorporation of AC resulted in a maximum 5.6-fold increase in unconfined compressive strength and a 1.8-fold increase in tensile strength for dispersive soil.Notably,a significant correlation was observed during the curing phase among soil dispersivity,mechanical properties,and pH values.Microscopic analyses revealed that the porous structure of AC facilitated a filling effect and enhanced adsorption capacity,which contributed to improved soil characteristics and reduced dispersivity.The release of hydrogen ions and the formation of aggregates promote water stability.Validation tests conducted on dispersive soil from northern Shaanxi demonstrated the efficacy of physical adsorption using AC as a viable method for modifying dispersive soil in the water conservancy hub.
基金funded by“The Fourth Phase of 2022 Advantage Discipline Engineering-Control Science and Engineering”,grant number 4013000063.
文摘The rapid development of new energy power generation technology and the transformation of power electronics in the core equipment of source-grid-load drives the power system towards the“double-high”development pattern of“high proportion of renewable energy”and“high proportion of power electronic equipment”.To enhance the transient performance of AC/DC hybrid microgrid(HMG)in the context of“double-high,”aπtype virtual synchronous generator(π-VSG)control strategy is applied to bidirectional interface converter(BIC)to address the issues of lacking inertia and poor disturbance immunity caused by the high penetration rate of power electronic equipment and new energy.Firstly,the virtual synchronous generator mechanical motion equations and virtual capacitance equations are used to introduce the virtual inertia control equations that consider the transient performance of HMG;based on the equations,theπ-type equivalent control model of the BIC is established.Next,the inertia power is actively transferred through the BIC according to the load fluctuation to compensate for the system’s inertia deficit.Secondly,theπ-VSG control utilizes small-signal analysis to investigate howthe fundamental parameters affect the overall stability of the HMG and incorporates power step response curves to reveal the relationship between the control’s virtual parameters and transient performance.Finally,the PSCAD/EMTDC simulation results show that theπ-VSG control effectively improves the immunity of AC frequency and DC voltage in the HMG system under the load fluctuation condition,increases the stability of the HMG system and satisfies the power-sharing control objective between the AC and DC subgrids.
