Rheological‐stiffness analysis of K+‐treated and CaCO3‐rich soils

Rheological methods are applied whenever flow behavior of substances needs to be investigated on a particle‐to‐particle scale executed by a parallel‐plate rheometer. Under oscillation, mechanical effects due to trafficking or vibrations caused by agricultural and forest machinery can be simulated by conducting amplitude‐sweep tests. Hooke's law of elasticity, Newton's law for ideal fluids (viscosity), Mohr‐Coulomb's equation, and, finally, Bingham's yielding are well‐known relationships and parameters in the field of rheology. This paper aims to introduce rheometry as a suitable method to determine the mechanical behavior of salt‐affected soils when subjected to external stresses. Potassium‐treated loamy sand from Halle and loamy silt from Kassel, both sites located in Germany, as well as loess from Israel, saturated with NaCl solutions in several concentrations were analyzed. From the stress‐strain–relationship parameters like the storage modulus G′ and the loss modulus G″, yield stress τ_y and the linear viscoelastic (LVE)–deformation range including the deformation limit γ_L, i.e., the transition from an elastic to a viscous state, were determined and calculated, respectively. With respect to salt effects, amplitude‐sweep tests on originally CaCO₃‐rich Avdat Loess show an increasing stability if saturated with higher NaCl concentrations. Comparable tests with K⁺‐rich substrates from Halle and Kassel evinced similar tendencies including the phenomenon of a critical K⁺ content, which becomes more obvious in case of the drained (–60h Pa) loamy‐silt samples from Kassel. Nevertheless, a higher microstructural stability is given in both substrates from Halle and Kassel, affected by different water contents, in general, which influence the exchange and availability of cations. The results verify that oscillatory tests are applicable for retracing salt‐induced effects, beside those ones, which are influenced by texture, current water content, and/or further chemical parameters.     

回归自变量的选择:Cp准则所有变量子集的回归

本文给出了一个计算所有可能变量子集的回归的BASIC程序,它充分考虑了BASIC语言内存较小的情况。并通过一个例子说用Cp准则选择回归自变量的方法。     

电极过程计算机研究

本文用计算机模拟了2-QADNm 线性扫描伏安曲线,模拟结果与实验数据十分接近,证实了所提出的电极反应机理,并估计了电极过程动力学参数。     

Three Phase Harmonic Power Flow Using PhaseComponent for Asymmetric Network

With the increasement of the harmonic quantity in power system ,single phase harmonic power flow calculation can't meet the needs. This paper discusses the components model in detail under harmonic condition in three phase distribution power system, include generator,transformer,line and load. Particularly, the transformer model considers the winding connection, the phase shifting among primary and secondary windings, and the off-normal tapping.The three-phase model of transformer, used in traditional harmonic power flow, may the preuent the model from converging, so the paper proposes a three phase back forward sweep harmonic load flow algorithm based on phase-components. At last, a test example was used to prove the algorithm. The results indicate that the proposed method is efficient.     

Stem quality assessment using terrestrial laser scanning technology: a case study of ash trees with a range of defects in two stands in Ireland

Information on stem quality of standing (broadleaf) timber is of great importance to the forestry sector to help optimise harvesting and marketing strategies. Manual assessment of such quality parameters in standing trees is extremely difficult, time consuming and costly. The objectives of this study were therefore to assess stem quality parameters such as taper, lean and sweep in ash (Fraxinus excelsior L.) stands, during leaves-on and leaves-off conditions, using terrestrial laser scanning technology, and to compare the estimated parameters with manually measured values in a mature and young stand. Diameter estimation was more accurate during the leaves-off condition in both stands, resulting in taper estimates that were closer to the manually obtained values as well. However, in general, the taper values did not match those obtained manually very closely. Given that the sample trees were chosen deliberately to include noticeable defects such as non-circularity, bending, swellings, knots resulting from the removal of branches and multiple leaders, this is not surprising. It probably is the case that the scanned data capture these defects more accurately than the manually collected data, especially when multi-scan data are used.     

厦门海域渔业资源现存量评析

2006-2007年夏季（2006年8月）、冬季（2007年1月）、春季（2007年4月）和秋季（2007年10月）在厦门海域利用底拖网渔船开展渔业资源调查．根据调查资料,对厦门海域（约2713km2）的渔业资源现状进行了评析．研究结果表明,4个季节渔业资源平均密度为981．97ks／km2,其中秋季居首位,约为1261．39ks／km2;冬季和夏季次之,分别为951．31kg/km2和936．93kg／km2,而春季资源密度最低,约为778．24kg/km2．各个季节的资源密度,鱼类均居首位,甲壳类次之,头足类最低．各季节鱼类优势种分别为：春季鱼类优势种有6种,以二长棘鲷（Parargyrops edita）幼鱼和短吻鳐（Leiognathus brevirostris）分别为第一和第二优势种;夏季有7种,以中华海鲶（Arius sinensis）和叫姑鱼（Johnius belengerii）分别为第一和第二优势种;秋季也有7种,以龙头鱼（Harpadon nehereus）、叫姑鱼和中华海鲶为主要优势种;冬季有4种,以叫姑鱼为最主要优势种．4个季节的平均渔业资源现存量约为1694．71t;渔业潜在可捕量约10523t．渔业资源分布与水温、水深及盐度关系较密切．该海域渔业资源已经明显衰退,急需加强渔业资源的管理和保护．     

基于选择消除分析挖掘豌豆耐冻相关基因

近年来，冬季的低温对豌豆生产造成严重损失。本试验对16 份极端耐冻豌豆和14 份极端冷敏感豌豆的全基因组重测序数据与参考基因组进行比对获得SNP，再基于过滤后的SNP 数据对所有材料进行系统发育树构建、主成分分析、连锁不平衡分析以及选择消除分析等，并依据选择消除分析的群体多样性（θπ）、杂合率（Hp）和群体分化（Fst）三者交集的前5%候选区域，最终筛选获得34 个与豌豆耐冻相关的基因。研究结果为豌豆耐冻品种选育和“冬豆北移”栽培模式提供理论支撑。