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带式输送机软启动方式比较分析 被引量:2
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作者 池秋霞 《露天采矿技术》 CAS 2013年第6期44-45,共2页
阐述目前国内露天煤矿生产系统普遍应用的大功率、多电机、长距离带式输送机的几种软启动方式,对软启动方式进行性能价格比较,并得出结论。介绍了带式输送机的刚性启动和软启动方式的性能;对带式输送机的CST可控启动装置和液力耦合器两... 阐述目前国内露天煤矿生产系统普遍应用的大功率、多电机、长距离带式输送机的几种软启动方式,对软启动方式进行性能价格比较,并得出结论。介绍了带式输送机的刚性启动和软启动方式的性能;对带式输送机的CST可控启动装置和液力耦合器两种机械软启动方式和电气软启动器、变频器两种电气软启动方式的优缺点进行了对比,并对各种软启动方式的具体应用提出建议。 展开更多
关键词 带式输送机 软启动方式 性价比较
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Improvement Methods for Genetic Evaluation of Hanwoo Cows
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作者 T. S. Yoon J. J. Ha Y. H. Song 《Journal of Agricultural Science and Technology(A)》 2011年第8期1310-1313,共4页
A total of 1,101 heads were used to improve the selection of superior cows in Gangwon regional Hanwoo. Characteristics of each cow were analyzed using ultrasound evaluation and trace of reproductive potential. A compa... A total of 1,101 heads were used to improve the selection of superior cows in Gangwon regional Hanwoo. Characteristics of each cow were analyzed using ultrasound evaluation and trace of reproductive potential. A comparison of live carcass traits classified by parity was analyzed in all characteristics. The results of the comparison showed all characteristic increased rapidly after the 2nd parity, and decreased after the 4th parity (P 〈 0.01). The result of comparison classified by the group showed a tendency, whereas Back Fat Thickness Ultrasound (BFTU) and P8 Fat Thickness Ultrasound (P8-FTU) were significant (P 〈 0.01) thinnest in Pedigree group and using a lot of reproduction in advanced group. Also, we made comparisons of the cow's calves on the carcass traits among the group. High quality calves of the pedigree group showed 30.77%. These are the highest carcass traits in meat quality grade above 1+ and yield grade above A. Frequency of fertilization failure per rump fat thickness showed a significantly (P 〈 0.0|) higher difference. The average frequency of fertilization failure demonstrated 1.11 times of experimental Hanwoo cows. In the analysis, frequency of fertilization failure appeared 0.9 times at rump fat thickness below 5 mm. However, it is higher than average above 5 mm. The result of the study will be used to improve cows, select optimum semen, as well as contribute to the improvement of farms income. 展开更多
关键词 Hanwoo cow ULTRASOUND CHARACTERISTIC BREEDING
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Assessment of effectiveness of nature reserves on the Tibetan Plateau based on net primary production and the large sample comparison method 被引量:6
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作者 张镱锂 胡忠俊 +7 位作者 祁威 吴雪 摆万奇 李兰晖 丁明军 刘林山 王兆锋 郑度 《Journal of Geographical Sciences》 SCIE CSCD 2016年第1期27-44,共18页
Twenty-one typical coupled large samples were chosen from areas within and surrounding nature reserves on the Tibetan Plateau using the large sample comparison method(LSCM).To evaluate the effectiveness of the nature ... Twenty-one typical coupled large samples were chosen from areas within and surrounding nature reserves on the Tibetan Plateau using the large sample comparison method(LSCM).To evaluate the effectiveness of the nature reserves in protecting the ecological environment,the alpine grassland net primary production(NPP) of these coupled samples were compared and the differences between them before and after their establishment as protected areas were analyzed.The results showed that:(1) With respect to the alpine grassland NPP,the ecological and environmental conditions of most nature reserves were more fragile than those of the surrounding areas and also lower than the average values for the Tibetan Plateau.(2) Of the 11 typical nature reserves selected,the positive trend in the NPP for Manzetang was the most significant,whereas there was no obvious trend in Taxkorgan.With the exception of Selincuo,the annual NPP growth rate in the nature reserves covered by alpine meadow and wetland was higher than that in nature reserves consisting of alpine steppe and alpine desert.(3) There were notable findings in 21 typical coupled samples:(a) After the establishment of the nature reserves,the annual rate of increase in the NPP in 76% of samples inside nature reserves and 82% of samples inside national nature reserves was higher than that of the corresponding samples outside nature reserves.(b) The effectiveness of ecological protection of the Mid-Kunlun,Changshagongma,Zoige and Selincuo(Selin Co) nature reserves was significant; the effectiveness of protection was relatively sig-nificant in most parts of the Sanjiangyuan and Qiangtang nature reserves,whereas in south-east Manzetang and north Taxkorgan the protection effectiveness was not obvious.(c) The ecological protection effectiveness was significant in nature reserves consisting of alpine meadow,but was weak in nature reserves covered by alpine steppe.This study also shows that the advantage of large sample comparison method in evaluating regional ecology change.Careful design of the samples used,to ensure comparability between the samples,is crucial to the success of this LSCM. 展开更多
关键词 nature reserves protection effectiveness large sample comparison method net primary production Tibetan Plateau
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