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Search Results: 1 - 10 of 344517 matches for " 王坤杰 "
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最大主应力预测点焊疲劳寿命研究
Fatigue Life Prediction for Spot Welded Joints Considering Major Principal Stress

,
- , 2016,
Abstract: 采用基于最大主应力的点焊疲劳寿命预测方法对拉剪受力状态下的电阻点焊疲劳寿命进行有限元模拟。使用壳单元、CWELD点焊连接单元建立点焊有限元模型,利用商业有限元软件Nastran进行线弹性分析。通过对比分析线弹性有限元分析结果、焊接接头疲劳试验数据,拟合出基于最大主应力的点焊疲劳寿命S-N曲线,并依据拟合的S-N曲线和有限元分析取得的最大主应力预测不同载荷水平下的点焊疲劳寿命。疲劳寿命预测结果与疲劳实验结果对比表明,不同载荷下的点焊疲劳寿命预测结果与实验寿命有良好的一致性。
The authors use major principal stress around the weld nugget of spot welding to predict fatigue life for spot welded joints in automotive body structures. The finite element model for spot welding specimens are established by using shell and CWELD elements. The stress field in the spot welding specimens is analyzed via Nastran software. Based on the computed major principal stress, the fatigue life is estimated by using the S-N curve which is from linear fitting based on the finite element analysis and fatigue test data of spot welding. The calculated fatigue life for spot welding is compared with the experimental to verify the validity of the calculation method. The used method is proven an effective in consolidating a series of fatigue data for spot welding subjected to tensile shear load
一种新的病态问题奇异值修正方案及其在大地测量中的应用
,欧吉
自然科学进展 , 2004,
Abstract: 根据观测方程设计矩阵奇异值的分布特点,将病态问题分为具有均匀下降型奇异值和阶梯型奇异值两种类型.针对均匀下降型奇异值提出了一种新的奇异值修正方案,其核心是将奇异值分成两部分分别修正.这种方案兼顾了解的分辨率与方差之间的折中,是一种更加合理的奇异值修正方案.经过实例验证,当法矩阵的条件数小于1010时,这种方案是非常有效的,与其他方法相比较,显著地提高了计算结果的精度.
鸭乙型肝炎病毒的致病性和致癌性研究──启东和高邮地区鸭的肝脏病理变化与血清中鸭乙型肝炎病毒的关系
张村 , 宝安 ,
扬州大学学报(农业与生命科学版) , 1994,
Abstract: ????为探讨鸭乙型肝炎病毒(DHBV)与鸭肝病及肝癌的关系,取鸭肝癌高发地区启东市2年以上鸭114只和低发地区高邮市1.5年以上鸭98只,分别经血清学检测鸭DHBV,逐个进行肝脏病理组织学检查,比较两地区带毒率和阳性鸭群与阴性鸭群的病变性质及程度,采用Ridit非参数检验方法,进行统计推断。发现无论是高邮鸭还是启东鸭,同一地区在相同条件下饲养的鸭群,DHBV阳性组和阴性组之间肝病的性质和程度以及肝癌检出率无显著差异;高邮阳性鸭群和启东阳性鸭群相比较,胆管增生、淀粉样变和细胞变性及肝癌检出卒等多项指标差异显著。进一步分析证明,造成这种差异的原因是由于病因不同所致。高邮鸭肝病发生的主要原因是东方次睾吸虫感染,而启东鸭肝病和肝癌发生的主要原因是黄曲霉毒素中毒。鸭乙型肝炎病毒的存在与否对两地区鸭群的肝病及肝癌的发生和发展,并无明显影响。
单频GPS快速定位中模糊度解算的一种新方法
欧吉,
科学通报 , 2003,
Abstract: 研究只利用几个历元的单频相位数据进行GPS快速定位的新方法.首先分析了GPS快速定位法矩阵的结构特性.基于Tikhonov正则化原理,针对这种特性,设计了一种正则化矩阵的构造方法.通过新的正则化矩阵的作用,减弱了法矩阵的病态性.新方法解算几个历元的单频GPS相位数据,可以得到比较准确的模糊度浮点解及其相应的均方误差矩阵,用均方误差矩阵代替协因数阵,结合LAMBDA方法,可准确快速地确定模糊度.以一个3km多的基线实测数据为例,新方法仅用5个历元(5秒)的单频L1相位数据,确定的整周模糊度值与长时间的Bernese软件解算的结果一致.197组序列解确定整周模糊度的成功率为100%.与传统的方法相比,新方法明显地提高了快速定位的准确性和效率.新方法在变形监测和准动态定位以及姿态确定等方面有良好的应用前景.
在线调整对到达运动中人体上肢刚性特性的影响
,左国
- , 2015, DOI: 10.3871/j.1004-7220.2015.04.355
Abstract: 目的 研究在线调整与运动中人体上肢刚性值之间的关系,提高人体刚性值测量的精度以及评判在线调整能力。方法 设计5类不同类型的上肢平面到达运动,通过施加快速扰动的方法,对运动过程的前期、前中期、中期、中后期和后期共5个位置的刚性值进行测量,探讨刚性值在受到在线调整影响时的变化规律,以及刚性幅值与运动精度之间的关系。结果 运动过程中刚性一直变化,而且刚性值的变化影响了最终的运动误差。运动过程中在线调整的发生会引起刚性幅值的改变,尤其是运动后期的刚性幅值,但是目前没有发现这一变化与在线调整发生的时间或者内容存在密切的联系。结论 在线调整在到达运动中扮演了重要的角色。考虑到在线调整的发生会引起刚性幅值的变化,在临床上,通过对患者在特定实验中刚性幅值的测量,结合其他医学诊断方法,可以更精确地表明患者当前在线调整功能的状况。
Objective To study the relationship between on-line correction and stiffness of the upper limb during human movements, so as to improve the measurement accuracy of stiffness and to assess the on-line correction capability. Methods Five kinds of upper limb goal-directed movements in a horizontal plane were designed. The stiffness values at 5 different positions, i.e. in the early period, early to mid period, mid period, mid to late period and late period separately during the movements with sudden perturbation were measured to investigate the regular pattern of human hand stiffness influenced by such on-line correction, as well as the relationship between the movement accuracy and hand stiffness. Results The stiffness was always varying during the movements, and the variation of the stiffness would influence the movement error. On-line correction during the movements could induce an increase in the value of stiffness amplitude, especially at the position in late period of the movement. However, no significant linkage was found between the change of stiffness and the occurrence time or content of on-line correction. Conclusions On-line correction plays an important role in goal-directed movements. Considering that on-line correction may cause a change in the amplitude of the stiffness, the on-line correction function of patients can be more accurately assessed by measuring stiffness value in specific experiments, combined with other medical diagnosis methods in clinic.
海洋酸化对海水青鳉性别分化的影响
宋露露,,宋佳
上海海洋大学学报 , 2018, DOI: 10.12024/jsou.20170502043
Abstract: 以海水青鳉作为研究对象,研究海洋酸化对其性别分化的影响。将刚受精的受精卵置于对照组(CO2浓度为480×10-6)和2个处理组(CO2浓度分别为1 000×10-6和2 000×10-6)的水体中,直到孵化出膜。将出膜后仔鱼饲养在对照组水体中至性成熟,然后通过形态学、组织学和遗传学方法,对每一尾实验鱼进行表现型和基因型的性别鉴定。经形态学判断,发现酸化处理组的雄雌比例显著高于对照组(P<0.01)。经形态学观察其第二性征和遗传学性别判断,对照组的青鳉从孵化到性成熟的个体中并未出现基因型和表现型性别不一致的个体,而在2个酸化处理组中,均有基因型为XX而表现型为雄性的个体,即性逆转雄性,性逆转率分别为38.4%和47.5%。
In this study, the effect of ocean acidification on sex differentation of marine medaka was studied. Fertilized eggs were incubated at three concentrations of CO2 (480×10-6, 1 000×10-6 and 2 000×10-6) and after hatching, the fry were bred under control condition (480×10-6) until adulthood. Phenotypic sex was judged from secondary sexual characteristics. The ratio of male to female in two treatment groups was significantly higher than that in the control group (P<0.01). Genotypic sex was determined by the presence or absence of the DMY gene. In the control group, phenotypic sex completely agreed with genotypic sex. However, in two treatment groups, there are some phenotypical males but genotypic female, which is sex-reversed XX male. The sex reversal rate was 38.4% and 47.5% at 1 000×10-6 and 2 000×10-6 concentration of CO2, respectively.
防治肾移植中缺血再灌注损伤的研究进展
Research progress on preventions of ischemia-reperfusion injury during kidney transplant

宫丽娜,
- , 2018, DOI: 10.7507/1001-5515.201804009
Abstract: 在肾移植中,虽然缺血再灌注损伤(IRI)诱发的非特异性炎症反应会导致移植肾生存能力的下降,但是 IRI 对肾移植远期存活率的影响是不确定的。本文综合回顾分析临床证据和实验室研究结果,以期阐明早期 IRI 与移植肾远期生存能力下降的关系。既往研究分析表明,早期 IRI 可能是通过功能性肾单位减少、移植血管损伤、慢性缺氧以及随后的纤维化等原因导致了移植失败。此外,IRI 也是诱发肾移植功能障碍、急性排斥反应和降低移植器官生存率的重要因素之一。因此,在肾移植中尝试用新的保护方法替代传统方法,或许可以更好地减轻缺血再灌注导致的肾损伤。本文通过综合回顾分析各种防治肾移植中 IRI 的新旧方法,希望可以有助于临床治疗。
During kidney transplant, the non-specific inflammatory response induced by ischemia-reperfusion injury (IRI) will lead to decreased survival ability of transplanted kidney. However, the effect of IRI on long-term survival rate of allograft is not sure. Here we illuminated the relationship between early IRI and decreased long-term survival ability of allograft by retrospectively analyzing the clinical evidences and laboratory investigations. Previous studies showed that early IRI resulted in the graft loss through reduction of renal functional mass, vascular injury, chronic hypoxia and subsequent fibrosis. IRI was also one of the main factors to induce dysfunction of transplanted kidney and acute rejection reaction, and to decrease the allograft survival. Therefore, it’s better to substitute traditional methods with novel measures during kidney transplant which may relieve the renal IRI much better.
RP-HPLC法测定中药材黄柏中小檗碱的含量
,朱红,大威,
中国中药杂志 , 1995,
Abstract: 用反相高效液相色谱法,安定为内标,ZorbaxC8柱,含30mmol/L。磷酸的乙腈-水(35:65)为流动相,于紫外346nm处测定了黄柏中小檗碱的含量。排除了巴马汀对小檗碱的干扰。平均回收率为101.7%,RSD为1.83%(n=20)。
基于反馈的精英教学优化算法
, , 振雷
自动化学报 , 2014, DOI: 10.3724/SP.J.1004.2014.01976
Abstract: ?精英教学优化算法(Elitistteaching-learning-basedoptimization,ETLBO)是一种基于实际班级教学过程的新型优化算法.本文针对ETLBO算法寻优精度低、稳定性差的问题,提出了反馈精英教学优化算法(FeedbackETLBO).在ETLBO算法的基础上,通过在学生阶段之后加入反馈阶段,增加了学生的学习方式,保持学生的多样性特性,提高算法的全局搜索能力.同时,反馈阶段是选举成绩较差的学生与教师交流,使成绩较差的学生快速向教师靠拢,使算法进行局部精细搜索,提高算法的寻优精度.对6个无约束及5个约束标准函数的测试结果表明,FETLBO算法与其他算法相比在寻优精度和稳定性上更具优势.最后将FETLBO算法应用于拉压弹簧优化设计问题及0-1背包问题,取得了满意结果.
纳米稀土氧化物/硫酸酯化壳聚糖杂化材料的制备及其抗凝血性能研究
高琦宽,,喜存
化学学报 , 2012, DOI: 10.6023/A1103231
Abstract: 利用接枝的方法制备了4种纳米RE2O3/硫酸酯化壳聚糖杂化材料(Nd2O3-TDI-CS,Eu2O3-TDI-CS,La2O3-TDI-CS,Sc2O3-TDI-CS,TDI=甲苯二异氰酸酯,CS=壳聚糖),用红外光谱、热重分析和扫描电镜表征了产物,结果表明壳聚糖接枝于经过活化后的纳米氧化物表面.抗凝血实验结果和复钙实验结果说明制备的4种杂化材料比纳米稀土氧化物具有更好的抗凝血性能.
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