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S. van Engelen H. Bovenhuis P.P.J. van der Tol M.H.P.W. Visker 《Journal of dairy science》2018,101(3):2226-2234
International environmental agreements have led to the need to reduce methane emission by dairy cows. Reduction could be achieved through selective breeding. The aim of this study was to quantify the genetic variation of methane emission by Dutch Holstein Friesian cows measured using infrared sensors installed in automatic milking systems (AMS). Measurements of CH4 and CO2 on 1,508 Dutch Holstein Friesian cows located on 11 commercial dairy farms were available. Phenotypes per AMS visit were the mean of CH4, mean of CO2, mean of CH4 divided by mean of CO2, and their log10-transformations. The repeatabilities of the log10-transformated methane phenotypes were 0.27 for CH4, 0.31 for CO2, and 0.14 for the ratio. The log10-transformated heritabilities of these phenotypes were 0.11 for CH4, 0.12 for CO2, and 0.03 for the ratio. These results indicate that measurements taken using infrared sensors in AMS are repeatable and heritable and, thus, could be used for selection for lower CH4 emission. Furthermore, it is important to account for farm, AMS, day of measurement, time of day, and lactation stage when estimating genetic parameters for methane phenotypes. Selection based on log10-transformated CH4 instead of the ratio would be expected to give a greater reduction of CH4 emission by dairy cows. 相似文献
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32Si是宇宙射线与空气中的Ar通过散裂反应产生的长寿命放射性核素,利用32Si可以开展广泛的应用研究。然而作为放射性核素关键数据的32Si半衰期数据仍然存在较大的偏差,这在很大程度上阻碍了32Si的应用。本工作利用中国原子能科学研究院的加速器质谱系统开展了32Si半衰期的测量。通过反应堆辐照Mg2P2O7生产32Si并制备出用于加速器质谱测量和活度测量的样品;利用加速器质谱技术进行了32Si/Si绝对比值的测定;通过液闪对样品进行了放射性活度测量,从而实现了32Si半衰期的测定,得到32Si的半衰期值为(182±16)a。 相似文献
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An Adaptive Measurement Scheme (AMS) is investigated with Compressed Sensing (CS) theory in Cognitive Wireless Sensor Network (C-WSN). Local sensing information is collected via energy detection with Analog-to-Information Converter (AIC) at massive cognitive sensors, and sparse representation is considered with the exploration of spatial temporal correlation structure of detected signals. Adaptive measurement matrix is designed in AMS, which is based on maximum energy subset selection. Energy subset is calculated with sparse transformation of sensing information, and maximum energy subset is selected as the row vector of adaptive measurement matrix. In addition, the measurement matrix is constructed by orthogonalization of those selected row vectors, which also satisfies the Restricted Isometry Property (RIP) in CS theory. Orthogonal Matching Pursuit (OMP) reconstruction algorithm is implemented at sink node to recover original information. Simulation results are performed with the comparison of Random Measurement Scheme (RMS). It is revealed that, signal reconstruction effect based on AMS is superior to conventional RMS Gaussian measurement. Moreover, AMS has better detection performance than RMS at lower compression rate region, and it is suitable for large-scale C-WSN wideband spectrum sensing. 相似文献
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为研究Cu元素对AMS6308钢耐温性的影响,采用SEM、TEM、EBSD、相分析和力学性能测试等手段,研究了不同回火温度下,AMS6308钢(含2%Cu)与不含Cu对比试验钢的组织与力学性能,探讨AMS6308钢中Cu元素对提高抗回火性能的作用。结果表明,随着回火温度提高,AMS6308钢强度先升后降,450 ℃出现峰值,并且整个回火温度区间强度均高于无Cu钢。400 ℃以下温度回火,Cu元素提高整体强度与抗回火性能,主要依靠固溶强化、增加M6C相的析出强化、细晶强化3种方式的共同作用,主要强化机制是M6C相析出强化。400 ℃以上温度回火,Cu元素主要依靠ε-Cu相的析出强化,提高强度与抗回火性能。ε-Cu相通过与位错的交互作用,产生强烈的沉淀强化,并在更高回火温度下,使钢保持较为完整的板条结构。 相似文献
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Fabien Prgaldiny Franois Krummenacher Birahim Diagne Franois Pêcheux Jean‐Michel Sallese Christophe Lallement 《International Journal of Numerical Modelling》2006,19(3):239-256
This paper presents a new compact model for the undoped, long‐channel double‐gate (DG) MOSFET under symmetrical operation. In particular, we propose a robust algorithm for computing the mobile charge density as an explicit function of the terminal voltages. It allows to greatly reduce the computation time without losing any accuracy. In order to validate the analytical model, we have also developed the 2D simulations of a DG MOSFET structure and performed both static and dynamic electrical simulations of the device. Comparisons with the 2D numerical simulations give evidence for the good behaviour and the accuracy of the model. Finally, we present the VHDL‐AMS code of the DG MOSFET model and related simulation results. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献