期刊文献+
共找到5篇文章
< 1 >
每页显示 20 50 100
Combined Selection Index for New Yorkshire Dam Line with High Prolificacy
1
作者 孙华 宋忠旭 +3 位作者 彭先文 李良华 董斌科 梅书棋 《Agricultural Science & Technology》 CAS 2013年第10期1443-1445,1461,共4页
The combined selection index used in the breeding of new Yorkshire dam line with high prolificacy according to breeding objects was formulated as /:2.272E- BVNB-0.056EBVDAYS. After 5 generations breeding, the two mai... The combined selection index used in the breeding of new Yorkshire dam line with high prolificacy according to breeding objects was formulated as /:2.272E- BVNB-0.056EBVDAYS. After 5 generations breeding, the two main selected traits such as total number of born and age at 100 kg weight was 12.17 piglets/litter and 165.18 d, respectively. The genetic improvements per generates was 0.156 and -2.198, respec- tively. The breeding objects of the new Yorkshire dam line with high prolificacy were basically reached. It indicated that the methods and index could be used in pig breeding. 展开更多
关键词 New Yorkshire dam line with high prolificacy Breeding objects com- bined selection index
下载PDF
双转子发动机转子-机匣碰摩振动特征研究 被引量:12
2
作者 王俨剀 王理 +1 位作者 廖明夫 丁小飞 《机械科学与技术》 CSCD 北大核心 2014年第4期614-620,共7页
双转子发动机发生转静碰摩时,会出现高低压转子组合频率(频率和、频率差),但无法区分高、低压转子碰摩。采用简化的动力学模型,讨论双转子发动机转子与机匣碰摩的情况,认为碰摩力往往是一个旋转的力,并对碰摩的三种形式进行了理论分析... 双转子发动机发生转静碰摩时,会出现高低压转子组合频率(频率和、频率差),但无法区分高、低压转子碰摩。采用简化的动力学模型,讨论双转子发动机转子与机匣碰摩的情况,认为碰摩力往往是一个旋转的力,并对碰摩的三种形式进行了理论分析和数值仿真。发现高压转子发生碰摩时,会出现高压转子的整数倍频NΩH及组合频率NΩH±ΩL的频率成分;低压转子碰摩时,则会出现低压转子的整数倍频NΩL及组合频率NΩL±ΩH的频率成分。组合频率成分在转子上反映并不显著,在机匣的振动响应中则会很突出。开展了双转子碰摩实验研究,实验结果和发动机实测结果均验证了上述结果的正确性。 展开更多
关键词 双转子发动机 转子-机匣 转子碰摩 振动特征 组合频率 低压转子 频率成分 高压转子
下载PDF
Nonlinear magneto-electric response of a giant magnetostrictive/piezoelectric composite cylinder 被引量:4
3
作者 Yuan-Wen Gao Juan-Juan Zhang 《Acta Mechanica Sinica》 SCIE EI CAS CSCD 2012年第2期385-392,共8页
In this study, we investigate the nonlinear cou- pling magneto-electric (ME) effect of a giant magnetostric- tive/piezoelectric composite cylinder. The nonlinear consti- tutive relations of the ME material are taken... In this study, we investigate the nonlinear cou- pling magneto-electric (ME) effect of a giant magnetostric- tive/piezoelectric composite cylinder. The nonlinear consti- tutive relations of the ME material are taken into account, and the influences of the nonlinear material properties on the ME effect are investigated for the static and dynamic cases, respectively. The influences of different constraint conditions on the ME effect are discussed. In the dynamic case considering nonlinear material properties, the double frequency ME response (The response frequency is twice the applied magnetic frequency) is obtained and discussed, which can be used to explain the experiment phenomenon in which the input signal with frequency f is converted to the output signal with 2f in ME laminated structures. Some calculations on nonlinear ME effect are conducted. The obtained results indicate that the nonlinear material properties affect not only the magnitude of the ME effect in the static case but also the ME response frequency in the dynamic case 展开更多
关键词 Nonlinear coupling ME effect Layered com- posite cylinder. Double frequency ME response
下载PDF
基于深度信念网络的低风速风电参与微电网频率优化控制 被引量:8
4
作者 边晓燕 印良云 +3 位作者 丁炀 赵健 周歧斌 李东东 《电力自动化设备》 EI CSCD 北大核心 2020年第6期76-82,共7页
低风速分散式风电接入微电网使得微电网能够利用低风速风资源为负荷供电,但其低惯量的特点也对微电网的频率稳定性提出了挑战。为了探究微电网中低风速风电机组(LWTG)如何有效参与抑制微电网频率波动,在LWTG中引入虚拟惯量控制、超速控... 低风速分散式风电接入微电网使得微电网能够利用低风速风资源为负荷供电,但其低惯量的特点也对微电网的频率稳定性提出了挑战。为了探究微电网中低风速风电机组(LWTG)如何有效参与抑制微电网频率波动,在LWTG中引入虚拟惯量控制、超速控制和下垂控制。针对风电机组最小转子转速限制,通过理论分析确定了合适的LWTG的参数;针对超速控制存在的盲区问题,利用深度信念网络来优化不同风速下的减载率以及虚拟惯量控制、下垂控制的控制参数;在低风速风况下验证了优化后的参数能够有效减少负荷波动引起的微电网动态频率跌落幅度,并获得较好的调频效果。 展开更多
关键词 微电网 低风速 深度信念网络 调频 超速控制 风电机组
下载PDF
Growth of gas bubbles in the biotissues with convective acceleration
5
作者 S. A. Mohammadein K. G. Mohamed 《International Journal of Biomathematics》 2014年第6期223-238,共16页
This paper presents formulae and explanation about the growth of a convective gas bubble in the blood and other tissues of divers who surface too quickly, concentration distribution around the growing bubble is also p... This paper presents formulae and explanation about the growth of a convective gas bubble in the blood and other tissues of divers who surface too quickly, concentration distribution around the growing bubble is also presented. The formulae are valid all over the growth stages, i.e. under variable ambient pressure while the diver is ascending, and under constant ambient pressure at diving stops or at sea level. The mathematical model is solved analytically by using the method of combined variables. The growth process is affected by tissue diffusivity, concentration constant and the initial void fraction, which is the dominant parameter. Results show that, the time of the complete growth, in the convective growth model, is shorter than those earlier presented by Mohammadein and Mohamed [Concentration distribution around a growing gas bubble in tissue, Math. Biosci. 225(1) (2010) 11-17] and Srinivasan et al. [Mathematical models of diffusion- limited gas bubble dynamics in tissue, J. Appl. Physiol. 86 (1999) 732-741] for the growth of a stationary gas bubble, this explains the effect of bubble motion on consuming the oversaturated dissolved gas from the tissue into growing bubble which leads to increment in the growth rate to be more than those presented in the previous stationary models. 展开更多
关键词 Gas bubble concentration distribution convective growth method of com- bined variables.
原文传递
上一页 1 下一页 到第
使用帮助 返回顶部