Swirl-Loop Scavenging(SLS) improves the performance of 2-stroke aircraft diesel engine because the involved swirl may not only benefit the scavenging process, but also facilitate the fuel atomization and combustion. T...Swirl-Loop Scavenging(SLS) improves the performance of 2-stroke aircraft diesel engine because the involved swirl may not only benefit the scavenging process, but also facilitate the fuel atomization and combustion. The arrangement of scavenge port angles greatly influences incylinder flow distribution and swirl intensity, as well as the performance of the SLS engine. However, the mechanism of the effect and visualization experiment are rarely mentioned in the literature. To further investigate the SLS, Particle Image Velocimetry(PIV) experiment and Computational Fluid Dynamics(CFD) simulation are adopted to obtain its swirl distribution characteristics, and the effect of port angles on scavenging performance is discussed based on engine fired cycle simulation. The results illustrate that Reynolds Stress Turbulence model is accurate enough for in-cylinder flow simulation. Tangential and axial velocity distribution of the flow, as well as the scavenging performance, are mainly determined by geometric scavenge port angles ageom and βgeom . For reinforcement of scavenging on cross-sections and meridian planes, ageomvalue of27° and βgeom value of 60° are preferred, under which the scavenging efficiency reaches as high as 73.7%. Excessive swirl intensity has a negative effect on SLS performance, which should be controlled to a proper extent.展开更多
Exhaust resonance effect on the 2-stroke engine aspiration is investigated via one-dimensional simulation on GT-Power.Result shows that exhaust resonance is established when the number of oscillation periods per engin...Exhaust resonance effect on the 2-stroke engine aspiration is investigated via one-dimensional simulation on GT-Power.Result shows that exhaust resonance is established when the number of oscillation periods per engine cycle derived from the engine speed and exhaust length is an integer.Exhaust resonance may raise or lower the trapping ratio,and the specific effect depends on the value of the number of oscillation periods per engine cycle.There is a liner regression relationship between the trapping ratio and average after back pressure.The primary way to improve the trapping ratio with the exhaust resonance is to increase the average after back pressure.The optimum exhaust resonance state is the one that suits the port timings so that the peak of exhaust pressure lies within the after charging period,raising the average after back pressure.For the case where the exhaust duration is 184°CA and the scavenge duration is 111°CA,the optimum number of oscillation periods per engine cycle is 3.展开更多
目的探析老年非致残性脑卒中患者血清dickkopf相关蛋白1(dickkopf-related protein 1,DKK-1)、富亮氨酸α-2糖蛋白1(leucine-richα-2-glycoprotein-1,LRG1)水平变化与认知损害的关系。方法回顾性选择2023年1月至2024年12月衡水市人民...目的探析老年非致残性脑卒中患者血清dickkopf相关蛋白1(dickkopf-related protein 1,DKK-1)、富亮氨酸α-2糖蛋白1(leucine-richα-2-glycoprotein-1,LRG1)水平变化与认知损害的关系。方法回顾性选择2023年1月至2024年12月衡水市人民医院神经内科收治的老年非致残性脑卒中患者114例,根据蒙特利尔认知评估量表(Montreal cognitive assessment,MoCA)评分分为认知损害组35例(MoCA评分<26分)和认知正常组79例(MoCA评分≥26分)。检测DKK-1、LRG1水平,并分析二者水平变化与老年非致残性脑卒中患者认知损害的关系。结果认知损害组年龄、病灶体积及美国国立卫生研究院卒中量表评分明显高于认知正常组,差异有统计学意义(P<0.01)。认知损害组和认知正常组发病2周DKK-1、LRG1水平明显低于入院时,差异有统计学意义(P<0.05)。认知损害组发病2周DKK-1、LRG1水平明显高于认知正常组,差异有统计学意义(P<0.01)。多因素logistic回归分析显示,发病2周DKK-1(OR=1.049,95%CI:1.024~1.074,P<0.01)、LRG1(OR=1.043,95%CI:1.008~1.079,P<0.05)水平、年龄(OR=1.290,95%CI:1.073~1.552,P<0.01)、病灶体积(OR=1.977,95%CI:1.175~3.327,P<0.05)是老年非致残性脑卒中患者发生认知损害的危险因素。ROC曲线分析显示,老年非致残性脑卒中患者发病2周DKK-1、LRG1水平、年龄、病灶体积评估发生认知损害的曲线下面积分别为0.807、0.720、0.661、0.729(P<0.01)。结论老年非致残性脑卒中患者血清DKK-1、LRG1水平持续较高可能与认知损害风险存在一定的关联,临床可借助这两种指标进行辅助评估。展开更多
目的基于核苷酸结合寡聚化结构域样受体3/半胱氨酸蛋白酶-1(NLRP3/caspase-1)信号通路探究二甲双胍对2型糖尿病(T2DM)合并脑卒中患者认知功能的改善作用。方法选取2021年2月至2022年5月就诊于邯郸市中心医院的63例T2DM,按照随机数字表...目的基于核苷酸结合寡聚化结构域样受体3/半胱氨酸蛋白酶-1(NLRP3/caspase-1)信号通路探究二甲双胍对2型糖尿病(T2DM)合并脑卒中患者认知功能的改善作用。方法选取2021年2月至2022年5月就诊于邯郸市中心医院的63例T2DM,按照随机数字表法将其分为对照组(n=32)与试验组(n=31),对照组给予钠-葡萄糖共转运蛋白2抑制剂(SGLT-2i)类药物治疗,试验组在对照组基础上给予二甲双胍治疗,两组患者均连续治疗12周。收集患者临床资料,对比治疗前后两组简易精神量表(MMSE)得分、蒙特利尔认知评估量表(MoCA)得分、空腹血糖(FBG)、糖化血红蛋白(HbA1c)、餐后2小时血糖(2 hPBG)、外周单核细胞中NLRP3炎性小体蛋白表达水平、caspase-1蛋白表达水平及血清IL-8、IL-1β水平;采用Pearson线性相关分析治疗后NLRP3、caspase-1、IL-18、IL-1β与FBG的相关性。结果治疗后,试验组MMSE、MoCA得分均增高,且明显高于对照组(P<0.05),试验组FBG、HbA1c、2 h PBG水平低于对照组(P<0.05),试验组NLRP3、caspase-1蛋白水平和IL-18、IL-1β水平较对照组明显更低(P<0.05);经Pearson线性相关分析显示,治疗后NLRP3、caspase-1、IL-18、IL-1β与FBG呈正相关(P<0.05)。结论二甲双胍治疗能够改善T2DM合并脑卒中患者的认知功能,降低血糖水平和炎症反应,这可能与其对NLRP3/caspase-1信号通路的调节作用有关。展开更多
目的探讨乙醛脱氢酶2(aldehyde dehydrogenase 2,ALDH2)基因型多态性与急性缺血性脑卒中严重程度的关系。方法选取2022年3月至2023年9月于北京市昌平区医院神经内科住院的224例急性缺血性脑卒中患者作为研究对象,所有患者均行ALDH2基因...目的探讨乙醛脱氢酶2(aldehyde dehydrogenase 2,ALDH2)基因型多态性与急性缺血性脑卒中严重程度的关系。方法选取2022年3月至2023年9月于北京市昌平区医院神经内科住院的224例急性缺血性脑卒中患者作为研究对象,所有患者均行ALDH2基因型检测,根据检测结果分为GG组(n=136)与GA/AA组(n=88),GG组基因型为野生型(ALDH2*1/*1),GA/AA组基因型为基因突变杂合子型(ALDH2*1/*2)与纯合子型(ALDH2*2/*2)。比较两组临床资料Alberta卒中操作早期急性卒中分级CT(Alberta stroke program early CT score,ASPECT)评分、美国国立研究院卒中量表(National Institutes of Health Stroke scale,NIHSS)评分及Barthel指数(Barthel index,BI)。结果两组性别、年龄、体重指数、同型半胱氨酸、总胆固醇、三酰甘油、低密度脂蛋白胆固醇、高密度脂蛋白胆固醇及高血压病史、吸烟史、饮酒史占比比较差异均无统计学意义。GG组ASPECT评分、BI均高于GA/AA组,NIHSS评分低于GA/AA组,差异有统计学意义(P<0.05)。结论ALDH2基因型与急性缺血性脑卒中严重程度有关,ALDH2基因突变型患者急性缺血性脑卒中严重程度更严重。展开更多
基金supported by the Basic Research Program of the National Natural Science Foundation of China (Nos. 51775025 and 51205015)China Key Research and Development Plan (No.2018YFB0104100)。
文摘Swirl-Loop Scavenging(SLS) improves the performance of 2-stroke aircraft diesel engine because the involved swirl may not only benefit the scavenging process, but also facilitate the fuel atomization and combustion. The arrangement of scavenge port angles greatly influences incylinder flow distribution and swirl intensity, as well as the performance of the SLS engine. However, the mechanism of the effect and visualization experiment are rarely mentioned in the literature. To further investigate the SLS, Particle Image Velocimetry(PIV) experiment and Computational Fluid Dynamics(CFD) simulation are adopted to obtain its swirl distribution characteristics, and the effect of port angles on scavenging performance is discussed based on engine fired cycle simulation. The results illustrate that Reynolds Stress Turbulence model is accurate enough for in-cylinder flow simulation. Tangential and axial velocity distribution of the flow, as well as the scavenging performance, are mainly determined by geometric scavenge port angles ageom and βgeom . For reinforcement of scavenging on cross-sections and meridian planes, ageomvalue of27° and βgeom value of 60° are preferred, under which the scavenging efficiency reaches as high as 73.7%. Excessive swirl intensity has a negative effect on SLS performance, which should be controlled to a proper extent.
文摘Exhaust resonance effect on the 2-stroke engine aspiration is investigated via one-dimensional simulation on GT-Power.Result shows that exhaust resonance is established when the number of oscillation periods per engine cycle derived from the engine speed and exhaust length is an integer.Exhaust resonance may raise or lower the trapping ratio,and the specific effect depends on the value of the number of oscillation periods per engine cycle.There is a liner regression relationship between the trapping ratio and average after back pressure.The primary way to improve the trapping ratio with the exhaust resonance is to increase the average after back pressure.The optimum exhaust resonance state is the one that suits the port timings so that the peak of exhaust pressure lies within the after charging period,raising the average after back pressure.For the case where the exhaust duration is 184°CA and the scavenge duration is 111°CA,the optimum number of oscillation periods per engine cycle is 3.
基金supported by the Youth Fund Project of the National Natural Science Foundation of China(No.82204837)Zhejiang Provincial Natural Science Foundation(No.LQ23H290004)+1 种基金the Key Project of Zhejiang Provincial Natural Science Foundation(No.LZ25H310002)the General Project of the National Natural Science Foundation of China(No.82073824).#These authors contributed equally to this work.
文摘目的探析老年非致残性脑卒中患者血清dickkopf相关蛋白1(dickkopf-related protein 1,DKK-1)、富亮氨酸α-2糖蛋白1(leucine-richα-2-glycoprotein-1,LRG1)水平变化与认知损害的关系。方法回顾性选择2023年1月至2024年12月衡水市人民医院神经内科收治的老年非致残性脑卒中患者114例,根据蒙特利尔认知评估量表(Montreal cognitive assessment,MoCA)评分分为认知损害组35例(MoCA评分<26分)和认知正常组79例(MoCA评分≥26分)。检测DKK-1、LRG1水平,并分析二者水平变化与老年非致残性脑卒中患者认知损害的关系。结果认知损害组年龄、病灶体积及美国国立卫生研究院卒中量表评分明显高于认知正常组,差异有统计学意义(P<0.01)。认知损害组和认知正常组发病2周DKK-1、LRG1水平明显低于入院时,差异有统计学意义(P<0.05)。认知损害组发病2周DKK-1、LRG1水平明显高于认知正常组,差异有统计学意义(P<0.01)。多因素logistic回归分析显示,发病2周DKK-1(OR=1.049,95%CI:1.024~1.074,P<0.01)、LRG1(OR=1.043,95%CI:1.008~1.079,P<0.05)水平、年龄(OR=1.290,95%CI:1.073~1.552,P<0.01)、病灶体积(OR=1.977,95%CI:1.175~3.327,P<0.05)是老年非致残性脑卒中患者发生认知损害的危险因素。ROC曲线分析显示,老年非致残性脑卒中患者发病2周DKK-1、LRG1水平、年龄、病灶体积评估发生认知损害的曲线下面积分别为0.807、0.720、0.661、0.729(P<0.01)。结论老年非致残性脑卒中患者血清DKK-1、LRG1水平持续较高可能与认知损害风险存在一定的关联,临床可借助这两种指标进行辅助评估。
文摘目的基于核苷酸结合寡聚化结构域样受体3/半胱氨酸蛋白酶-1(NLRP3/caspase-1)信号通路探究二甲双胍对2型糖尿病(T2DM)合并脑卒中患者认知功能的改善作用。方法选取2021年2月至2022年5月就诊于邯郸市中心医院的63例T2DM,按照随机数字表法将其分为对照组(n=32)与试验组(n=31),对照组给予钠-葡萄糖共转运蛋白2抑制剂(SGLT-2i)类药物治疗,试验组在对照组基础上给予二甲双胍治疗,两组患者均连续治疗12周。收集患者临床资料,对比治疗前后两组简易精神量表(MMSE)得分、蒙特利尔认知评估量表(MoCA)得分、空腹血糖(FBG)、糖化血红蛋白(HbA1c)、餐后2小时血糖(2 hPBG)、外周单核细胞中NLRP3炎性小体蛋白表达水平、caspase-1蛋白表达水平及血清IL-8、IL-1β水平;采用Pearson线性相关分析治疗后NLRP3、caspase-1、IL-18、IL-1β与FBG的相关性。结果治疗后,试验组MMSE、MoCA得分均增高,且明显高于对照组(P<0.05),试验组FBG、HbA1c、2 h PBG水平低于对照组(P<0.05),试验组NLRP3、caspase-1蛋白水平和IL-18、IL-1β水平较对照组明显更低(P<0.05);经Pearson线性相关分析显示,治疗后NLRP3、caspase-1、IL-18、IL-1β与FBG呈正相关(P<0.05)。结论二甲双胍治疗能够改善T2DM合并脑卒中患者的认知功能,降低血糖水平和炎症反应,这可能与其对NLRP3/caspase-1信号通路的调节作用有关。
文摘目的探讨乙醛脱氢酶2(aldehyde dehydrogenase 2,ALDH2)基因型多态性与急性缺血性脑卒中严重程度的关系。方法选取2022年3月至2023年9月于北京市昌平区医院神经内科住院的224例急性缺血性脑卒中患者作为研究对象,所有患者均行ALDH2基因型检测,根据检测结果分为GG组(n=136)与GA/AA组(n=88),GG组基因型为野生型(ALDH2*1/*1),GA/AA组基因型为基因突变杂合子型(ALDH2*1/*2)与纯合子型(ALDH2*2/*2)。比较两组临床资料Alberta卒中操作早期急性卒中分级CT(Alberta stroke program early CT score,ASPECT)评分、美国国立研究院卒中量表(National Institutes of Health Stroke scale,NIHSS)评分及Barthel指数(Barthel index,BI)。结果两组性别、年龄、体重指数、同型半胱氨酸、总胆固醇、三酰甘油、低密度脂蛋白胆固醇、高密度脂蛋白胆固醇及高血压病史、吸烟史、饮酒史占比比较差异均无统计学意义。GG组ASPECT评分、BI均高于GA/AA组,NIHSS评分低于GA/AA组,差异有统计学意义(P<0.05)。结论ALDH2基因型与急性缺血性脑卒中严重程度有关,ALDH2基因突变型患者急性缺血性脑卒中严重程度更严重。
