深水细长柔性立管涡激振动响应形式判定参数研究

利用有限元数值模拟方法研究了深水细长柔性立管在正弦形式涡激升力作用下的动响应,并通过量纲分析结合函数拟合方式给出了判定立管涡激振动响应形式的无量纲参数的表达式和临界值,该参数与系统阻尼(包括流体阻尼和结构阻尼)、结构模态阶数及结构长度等有关。在实际海洋工程中,当设计或监测人员在预测立管的涡激振动响应时,可以先利用本文方法判定振动响应形式,然后根据响应形式选择合适的预报模型。

长白山森林植被资源对气候变化的响应分析

长白山森林植被对我国的气候有很强的调节作用,但在当前气候全球变化这一大背景下,长白山的森林植被资源也受到了一定影响。基于对当前气候变化主要形式的研究,结合对长白山森林植被资源变化形式的调查,分析了长白山森林植被资源对气候变化的响应情况,在此基础上提出消除正反馈响应的措施,提高对长白山森林植被的保护效果。

Differences in Light Response Curve and CO_2 Response Curve of Korla Fragrant Pear Trees in Different Training Systems

[Objective] This study was conducted to evaluate three training systems for Korla fragrant pear trees by comparing the characteristic parameters of light response curve and CO2 response curve, and to provide some theoretical basis for improving the pruning techniques of Korla fragrant pear trees. [Method] The light response curve and CO2 response curve of the trees trained to three systems were measured by LI-6400 portable photosynthesis system. The SPAD value was measured using SPAD-502 chlorophyll meter, and specific leaf weight was calculated, to evaluate the effects of the three training systems. [Result] The CO2 response curves of the three training systems were basically in agreement with their light response curves, but there were some differences in their characteristic parameters. Among the three training systems, the maximum net photosynthetic rate, apparent quantum yield and light compensation point of espalier trained trees were the highest, while their light saturation point was the lowest. The CO2 saturation point of delayed-open central leader trained trees and open center trained trees were 1 752 and 1 665 μmol/mol, both of which were much higher than that of espalier trained trees. In addition, the carboxylation efficiency and photorespiration rate of espalier trained trees were both higher than those of delayed-open central leader trained trees and open center trained trees, while the CO2 compensation point of espalier trained trees was the lowest. The leaf SPAD value of espalier trained trees was the largest, followed by that of open center trained trees, and the leaf SPAD value of delayed-open central leader trained trees was the smallest. In addition, the leaf area and specific leaf weight of espalier trained trees were both the highest, followed by those of open center trained trees. [Conclusion] Among the training systems for Korla fragrant pear trees, the espalier training system had better ability to capture light, higher photosynthetic productivity and strongest adaptability to light environment, and open center training system takes the second place. On the contrary, delayed-open central leader training system has the weakest adaptability to light environment, but it can adapt to a higher CO2 concentration. In summary, for the training of Korla fragrant pear trees, espalier training system, which has the highest theoretical yield, is the best among the three training systems, and delayed-open central leader training system is the worst.

Dynamic Response of Structure under Blast Load

The paper follows from the theory of explosion and interaction of an impact wave formed by the explosion and a structure. Firstly, the paper determines the parameters of the blast wave excited by a small charge explosion. The empirical formulas on the basis of our own experimental results are shown and used for the structure analysis. Evaluations of structures loaded by an explosion based on dynamic response in rotations round the central line of plate or beam systems during the dynamic load of this type is discussed in the paper and comparison of own limit values and published ones is presented. Blast loads typically produce very high strain rates in the range of 102 to 10-4 s-1. The effect of strain rate for concrete material is discussed. The formulas for increased compressive strength of concrete and steel reinforcement are presented. The ductility of structural members is influenced by the corresponding values under high strain rate of reinforcement, Damage to the structure is assessed accordingly firstly by the angle of rotation of the middle axis/surface, and secondly by the limit internal forces of the selected structure. The extreme nature of blast resistance makes it necessary to accept that structural members have some degree of inelastic response in most cases. This enables the application of structure dissipation using the ductility factor and increased of concrete strength. The limits are correlated with qualitative damage expectations. The methodology of dynamic response assessment and its application to the simple bridge structure is discussed.

Melanopsin-expressing retinal ganglion cell loss and behavioral analysis in the Thy1-CFP-DBA/2J mouse model of glaucoma

In this study, the role of melanopsin-expressing retinal ganglion cells （mRGCs） in the glaucoma-induced depressive behavioral response pattern was investigated. The CFP-D2 transgenic glaucoma animal model from five age groups was used in this study. Immunohistochemical labeling, quantitative analysis of mRGC morphology, open field test （OFT）, and statistical analysis were used. In comparison with C57 BL/6 mice, the age-matched CFP-D2 mice had significantly elevated intraocular pressure （lOP）. We observed parallel morphological changes in the retina, including a reduction in the density of cyan fluorescent protein- （CFP） expressing cells （cells mm^-2 at 2 months of age, 1309±26; 14 months, 878±30, P〈0.001）, mRGCs （2 months, 48_＋3; 14 months, 19±4, P〈0.001）, Brn3b-expressing RGCs （2 months, 1283±80; 14 months, 950±31, P〈0.001）, Brn-3b expressing mRGCs （5 months, 50.17%±5.5%; 14 months, 12.61%±3.8%, P〈0.001）, and reduction in the dendritic field size of mRGCs （mm^2 at 2 months, 0.077±0.015; 14 months, 0.065±0.015, P〈0.05）. CFP-D2 mice had hyperactive locomotor activity patterns based on OFT findings of the total distance traveled, number of entries into the center, and time spent in the center of the testing apparatus. The glaucoma induced hyperactive response pattern could be associated with dysfunctional mRGCs, most likely Brn-3b-positive mRGCs in CFP-D2 mice.

Nonlinear identification of electro-magnetic force model

Conventional attractive magnetic force models (proportional to the coil current squared and inversely proportional to the gap squared) cannot simulate the nonlinear responses of magnetic bearings in the presence of electromagnetic losses,flux leakage or saturation of iron.In this paper,based on results from an experimental set-up designed to study magnetic force,a novel parametric model is presented in the form of a nonlinear polynomial with unknown coefficients.The parameters of the proposed model are identified using the weighted residual method.Validations of the model identified were performed by comparing the results in time and frequency domains.The results show a good correlation between experiments and numerical simulations.