期刊文献+
共找到5篇文章
< 1 >
每页显示 20 50 100
船舶动力机械螺旋桨在不同湍流的动力性能仿真
1
作者 刘伟 万志勇 《舰船科学技术》 北大核心 2018年第10X期4-6,共3页
不同动力机械螺旋桨在湍流环境下进行动力性能仿真过程中,存在量化误差较大的问题,为此提出船舶动力机械螺旋桨在不同湍流的动力性能仿真。分别设计螺旋桨动力性能仿真平台硬件结构和软件系统,实现螺旋桨动力性能仿真平台构建;基于仿真... 不同动力机械螺旋桨在湍流环境下进行动力性能仿真过程中,存在量化误差较大的问题,为此提出船舶动力机械螺旋桨在不同湍流的动力性能仿真。分别设计螺旋桨动力性能仿真平台硬件结构和软件系统,实现螺旋桨动力性能仿真平台构建;基于仿真平台对船舶动力机械螺旋桨湍流流体动力学进行分析,通过平台大数据技术,实现船舶动力机械螺旋桨在不同湍流的动力性能仿真分析。试验数据表明,本文系统仿真效果与常规仿真方法相比,量化准确率提升10.25%,适合不同环境下的船舶螺旋桨动力性能分析。 展开更多
关键词 船舶动力 机械螺旋桨 湍流动力 性能仿真
下载PDF
Synthesis of Salmon Calcitonin Analogs Using Fmoc-based Chemistry on MBHA Resins
2
作者 Bin YANG Zhen Kai DING +1 位作者 Zong Jin HAN Qi Kai ZHANG(Beijing Institute of Pharmacology and Toxicology, Beijing 100850) 《Chinese Chemical Letters》 SCIE CAS CSCD 1999年第7期549-552,共4页
Peptide analogs of salmon calcitonin (sCT) were synthesized by using Fmoc-based chemistry on MBHA resins. Salmon calcitonin was modified by 1) cysteines at positions 1 and 7 were replaced by valine and alanine respect... Peptide analogs of salmon calcitonin (sCT) were synthesized by using Fmoc-based chemistry on MBHA resins. Salmon calcitonin was modified by 1) cysteines at positions 1 and 7 were replaced by valine and alanine respectively to result in open chain analogs, 2) the glycine at position 30 was replaced by alanine, D-alanine and sarcosine respectively, and 3) some residues were deleted besides the above two modifications. A modified two-step deprotection / cleavage procedure, in which a solvent of TFA / TMSBr / thioanisole / EDT / m-cresol combines with HF cleavage, was adopted in SPPS. 展开更多
关键词 salmon calcitonin analogs Fmoc-based SPPS MBHA resin the two-step deprotection/cleavage procedure
下载PDF
贸易自由化与中国性别就业差异 被引量:4
3
作者 席艳乐 陈小鸿 《现代财经(天津财经大学学报)》 CSSCI 北大核心 2014年第7期80-91,102,共13页
选用CHIP数据库1995、2002和2007年的城镇调查数据,利用截面Probit模型和Heckman两步法来研究贸易自由化对中国两性就业差异的影响。研究表明:随着贸易自由化程度的提升,个体劳动参与率呈现上升趋势;但是,贸易自由化对不同技能个体劳动... 选用CHIP数据库1995、2002和2007年的城镇调查数据,利用截面Probit模型和Heckman两步法来研究贸易自由化对中国两性就业差异的影响。研究表明:随着贸易自由化程度的提升,个体劳动参与率呈现上升趋势;但是,贸易自由化对不同技能个体劳动力的就业状况存在着显著差异化的影响。总体而言,无论对于男性或女性劳动力,贸易自由化对高技能两性劳动力的就业促进效应更为明显,而对低技能劳动力的就业促进作用相对较小,甚至更多为负;而对于同一技能的两性劳动力而言,贸易自由化对男性就业的影响要大于女性。因此,进一步完善开放型经济体系、提高女性教育水平意义重大。 展开更多
关键词 贸易自由化 性别就业差异 heckman两步法 截面Probit模型
原文传递
Statistical Inferences in a Partially Linear Model with Autoregressive Errors
4
作者 Xiao-hui LIU Yu WANG +1 位作者 Ya-wen FAN Yu-zi LIU 《Acta Mathematicae Applicatae Sinica》 SCIE CSCD 2022年第4期822-842,共21页
In this paper,we consider the statistical inferences in a partially linear model when the model error follows an autoregressive process.A two-step procedure is proposed for estimating the unknown parameters by taking ... In this paper,we consider the statistical inferences in a partially linear model when the model error follows an autoregressive process.A two-step procedure is proposed for estimating the unknown parameters by taking into account of the special structure in error.Since the asymptotic matrix of the estimator for the parametric part has a complex structure,an empirical likelihood function is also developed.We derive the asymptotic properties of the related statistics under mild conditions.Some simulations,as well as a real data example,are conducted to illustrate the finite sample performance. 展开更多
关键词 partially linear model autoregressive errors two-step procedure profile empirical likelihood
原文传递
Generalized Cointegrated Time Series: Representation and Estimation
5
作者 ZHANG Xibin and ZHANG Shiying School of Management,Tianjin University,300072,P.R.China 《Systems Science and Systems Engineering》 CSCD 1998年第2期9-16,共8页
Cointegration analysis is often of special interest in the analysis of nonstationary vector valued time series, especially for the vector with higher order integrated components. In this paper we present the represen... Cointegration analysis is often of special interest in the analysis of nonstationary vector valued time series, especially for the vector with higher order integrated components. In this paper we present the representation theorem for a generalized cointegrated system, and formulate the generalized error correction model(GECM). We also provide the modified EG two step procedure to estimate the parameters in a GECM. The paper extends some important results of cointegration into the analysis of generalized cointegration, and is of great importance in the analysis of nonstationary time series. 展开更多
关键词 generalized error-correction model(GECM) representation theorem modified EG two-step procedure.
原文传递
上一页 1 下一页 到第
使用帮助 返回顶部