液电混合直线驱动系统位置控制特性研究

提出了一种采用电-机械直线执行器和液压缸的液电混合直线驱动系统。为消除电-机械直线执行器和液压缸之间的耦合影响,液压泵和比例阀协同控制液压缸输出力和运行方向,满足系统负载力需求,电-机械直线执行器用于运动控制,并补偿液压缸输出力波动和外部干扰力。为实现上述目标,设计了基于扩张状态观测器的电-机械直线执行器自适应滑模控制方法,以估计的负载力调节泵压力和比例阀开度,对液压缸输出力进行调控。比例阀在系统运行中主要用于控制液压缸运动方向,阀开度较大,可显著降低节流损失。通过仿真和试验分析了系统的运行特性和能效特性。结果表明,该系统具有良好的位置控制特性,能量效率高,较传统阀控系统能耗减少51%。     

Cohort‐specific variation in juvenile coho salmon habitat use

In this study, we examined summer and fall freshwater rearing habitat use by juvenile coho salmon (Oncorhynchus kisutch) in the quickly urbanising Big Lake drainage in south‐central Alaska. Habitat use was assessed by regressing fish count data against habitat survey information across thirty study sites using generalised linear mixed models. Habitat associations were examined by age‐0 and age‐1+ cohorts separately, providing an opportunity to compare habitat use across different juvenile coho salmon life stages during freshwater rearing. Regression results indicated that the age‐0 cohorts were strongly associated with shallow, wide stream reaches with in‐stream vegetation, whereas age‐1+ cohorts were associated with deeper stream reaches. Furthermore, associations between fork length and habitat characteristics suggest cohort‐specific habitat use patterns are distinct from those attributable to fish size. Habitat use information generated from this study is being used to guide optimal fish passage restoration planning in the Big Lake drainage. Evidence for habitat use partitioning by age cohort during freshwater juvenile rearing indicates that pooling age cohorts into a single “juvenile” stage for the purposes of watershed management may mask important habitat use dynamics.     

试论速生丰产林持续发展的种苗问题及其对策

为保证福建省速生丰产林持续优质发展，系统分析了与营造速生丰产林相关的种苗基础和种苗问题，提出了与发展速生丰产林相适应的种苗对策．     

空间矩阵的线性空间性研究

针对矩阵函数求导时产生的情形,提出立体矩阵这一概念,建立起立体矩阵的初步理论知识体系,并总结了立体矩阵的运算的一系列基本性质,构造了实矩阵域,而后考虑了立体矩阵在实数域和矩阵线性空间。     

河流水质污染中的反问题（Ⅱ）

继续讨论了一类半线性抛物偏微分方程的反问题，在一定条件下，得到了问题的解的存在性，唯一性，并给出了近似解法。     

石羊河流域生态环境问题及综合整治意见

石羊河流域生态环境存在着严重的问题，主要是由于人口对生态环境的压力过大、水资源利用不当等因素引起的；对存在的问题进行了剖析，并从持续发展和综合生态系统的观点，将石羊河流域作为以水维系的生态系统整体。阐述了石羊河流域祁连山区实行造林和封育措施，绿洲平原区实行节水型持续农业的系统环境整治的技术措施与意见。     

Yield Stability of Winter Wheat (Triticum sp.) Cultivars and Lines

The purpose of this study was to compare responsiveness to environment as well as the stability of newly developed promising lines with traditional commercial cultivars. Subject research was conducted in Ankara between 1983-1989 on common and durum wheat cultivars and lines. Regression coefficient (b) was used as the criterion of genotypes' responsiveness to environment whereas deviation from regression (S²d) and coefficient of determination (r²) were used as stability parameters. Each experiment year was regarded as an environment and yield average of each year was used as the environmental index.
In consequence of the research, it was determined that new varieties with high yield, adaptable to diverse environments could be developed by means of hybridizations between parents having different genetic characteristics which were provided from diverse ecological regions.     

一类正规矩阵的反问题

In this paper, we consider the inverse problems for a kinds of normal matrices. Some necessary and sufficient conditions for existence of solution of these problems are given. The expression of the general solution is given.     

微卫星DNA与延边黄牛肉用生长性状关系

选择与肉牛主要生产性状紧密连锁的 5个微卫星位点 ,以肉牛线性体型评分方法作为衡量肉牛生长发育的指标 ,运用最小二乘法拟合线性模型 ,分析了延边黄牛肉用生产性状与微卫星标记的关系 ,并分析了微卫星 ETH10和IDVGA4 6位点的不同基因型与肉用生产性状的关系。结果表明 ,微卫星 EHT10位点的等位基因 2 0 9对外貌线性评定中的背线性状、肌肉度线性评定中的肩部性状有正面影响 ,等位基因 2 13对外貌线性评定中的系部、肌肉度线性评定中的尻形状和细致度线性评定中的骨骼及皮肤性状有正面影响 ,而等位基因 2 15对外貌线性评定中的背线性状、肌肉度线性评定中的尻形状有负面影响 ;微卫星 IDVGA4 6位点的等位基因 2 4 9对背线、前肢和后肢等外貌线性评定性状 ,肌肉度线性评定的腰宽以及细致度线性评定的骨骼和皮肤性状有正面影响 ,等位基因 2 0 3对外貌评定性状的头部、背线 ,肌肉度评定性状腰宽以及细致度评定性状骨骼和皮肤有负面影响 ,等位基因 2 4 5对腰宽性状也起到负面影响     

河北省承德地区防护林体系林种结构的最佳模式

本文用线性规划方法,把以防护效益为主并满足社会需求作为约束条件,使防护林工程的费用最小作为目标,计算出了河北省承德地区防护林体系林种结构的61个方案。对不同情况,如资金不足、取得较好的经济效益、解决木材供需矛盾以及其它条件的变化等等,可以从61个方案中选出一个最佳方案。