Feed and reproductive efficiency differences between divergently selected lines for birthweight environmental variability in mice

Sustainability has come to play an important role in agricultural production. A way to combine efficiency with sustainability might be by searching for robust animals that can be selected for the homogeneity of certain traits. Furthermore, the optimization of feed efficiency is one of the challenges to improve livestock genetics programmes, but this might compromise reproductive efficiency. Animals from two divergent mouse lines, regarding variability of birthweight, were used to check whether homogeneity was also related to both feed and reproductive efficiency. The objective of this study was to use these divergent lines of mice to compare them with their feed efficiency and the reproductive capacity. Animal weight, weight gain, feed intake, relative intake and cumulated transformation index were considered as feed efficiency traits. Animals from the low line had both lower weight and feed intake from 21 to 56 days. They had a worse transforming index in the three last weeks when litter size was fitted as an effect of the model, but the lines become similar if the higher litter size of the low line was not included. Reproductively, the low line performed better considering the number of females having parturitions, the number of parturitions, and with higher litter size and survival in both parturitions. Hence, the low variability line was preferred because of reproductive efficiency without seriously affecting its feed efficiency. Homogeneity seemed to be related to robustness with similar feed efficiency but higher reproductive efficiency.     

模糊控制在水温电动比例调节控制系统中的应用

在电动比例调节器控制系统中,由于进入调节阀内冷、热水温度的随机性,而控制输出水温恒定性的特点,要求精确控制温度难度较大,采用模糊控制能够很好的解决上述问题,本文提出了一种采用CRI推理模糊查表法实现对比例调节阀的精确控制方案。     

任意秩多元线性模型中最优预测的稳健性

研究了任意秩多元线性模型中最优线性无偏预测的稳健性，即对任一线性可预测变量，得到了其关于协方差矩阵具有稳健性的充要条件.     

基于广义Arnold变换与支持向量机的图像水印算法

提出了一种基于广义Arnold变换与支持向量机模型的图像数字水印算法．选定的二值水印图像经过置乱以后,水印的嵌入位置通过广义Arnold变换随机产生,利用部分选定位置图像块中像素之间的关系来训练支持向量机,并采用水印嵌入增强处理技术,加强了水印的嵌入强度．在训练好的支持向量机辅助下,水印的检测过程可以看作是嵌入算法的一个逆过程．实验结果表明,该算法具有较好的鲁棒性,能有效抵抗Jpeg压缩、噪声等多种攻击．     

低频水印算法的研究与应用

数字水印技术作为版权保护的重要手段已在各行业得到广泛研究和应用,在DCT(离散余弦变换)域水印中如何保证水印稳健性和提高水印的不可见性是关键.本文给出了具有良好不可见性的DCT域中频数字水印和较强鲁棒性的低频水印算法,以及改进低频水印不可见性的方法.     

The design of torque dynamic sliding mode controller in permanent magnet synchronous generator for wind turbine

Permanent magnet synchronous generator for wind turbine is a multivariable nonlinear system with strong coupling. Considering the influence of the volatile parameters of the generator on the performance of vector control, the torque dynamic sliding-mode control strategy is further studied. The proposed first order dynamic sliding-mode control strategy reduces the chattering by using a new switch function constituted with derivative element. With the dynamic sliding-mode controller in the power outer loop, the PMSG vector control system shows excellent robustness and insensitivity to the parameters and disturbance, which is confirmed by simulation.     

线性天线阵列自抗扰的田间轮式小车控制系统研制

随着移动通信技术的发展,阵列技术也得到了广泛应用,并形成了智能天线的研究领域,而具有自适应和抗干扰能力的线性阵列天线是研究的热点。为此,提出了一种具有自抗扰能力的田间追随小车控制系统,并设计了小车的机械与传动结构。该小车利用线性阵列天线可以简单而灵活地操作控制信号,从而可以获得理想的空间定向波束,充分高效地利用用户信号,并删除或者抑制干扰信号。设计了田间追踪小车的样车,并设计了一个由N个天线单元组成的线性阵列。通过测试发现:小车在受外界转矩干扰后,系统的横向和纵向通道仍然能够很好地追随各自的设定值,具有较好的鲁棒性,可以保证在田间复杂环境和信号干扰的情况下,具有较高的作业效率和精度。     

Pole Normal Assignment for Linear Control Systems

The eigenvalues of a normal matrix are not sensitive to its elements perturbation. Based on the fact, the pole normal assignment problem for linear control systems is discussed. The aim is to find a state feedback control law. When the closed-loop system has desired poles and the closed-loop system matrix is a normal matrix, the robustness of the control system is enhanced. For linear constant systems, a necessary and sufficient condition is given to normal assignment of the desired poles. When the condition holds, a unified expression of the state feedback control laws is showed. An example is given for illustration of the proposed algorithm.     

Challenges to design-oriented breeding of root system architecture adapted to climate change

Roots are essential organs for capturing water and nutrients from the soil. In particular, root system architecture (RSA) determines the extent of the region of the soil where water and nutrients can be gathered. As global climate change accelerates, it will be important to improve belowground plant parts, as well as aboveground ones, because roots are front-line organs in the response to abiotic stresses such as drought, flooding, and salinity stress. However, using conventional breeding based on phenotypic selection, it is difficult to select breeding lines possessing promising RSAs to adapted to abiotic stress because roots remain hidden underground. Therefore, new breeding strategies that do not require phenotypic selection are necessary. Recent advances in molecular biology and biotechnology can be applied to the design-oriented breeding of RSA without phenotypic selection. Here I summarize recent progress in RSA ideotypes as “design” and RSA-related gene resources as “materials” that will be needed in leveraging these technologies for the RSA breeding. I also highlight the future challenges to design-oriented breeding of RSA and explore solutions to these challenges.     

基于复杂网络理论的西藏巴宜区森林景观空间结构研究

西藏巴宜区降水量丰富,但地质灾害频发,森林生态系统的水源涵养功能取决于森林景观空间结构的优劣,这对于区域生态稳定至关重要。以西藏巴宜区为研究区,基于复杂网络理论和景观生态学分析方法识别并构建区域森林景观空间网络,并运用复杂网络特征指标及鲁棒性分析方法分析该森林景观空间网络的拓扑结构特征及抗破坏能力。结果表明：西藏巴宜区的森林景观空间网络度分布呈现幂律分布,具有无标度性特征,该网络具有非均匀特性,网络结构稳定性较差,且随机攻击下的边与节点恢复鲁棒性优于恶意攻击下的恢复鲁棒性。