Three Dimensional Coupling between Elastic and Thermal Fields in the Static Analysis of Multilayered Composite Shells

This new work aims to develop a full coupled thermomechanical method including both the temperature profile and displacements as primary unknowns of the model.This generic full coupled 3D exact shell model permits the thermal stress investigation of laminated isotropic,composite and sandwich structures.Cylindrical and spherical panels,cylinders and plates are analyzed in orthogonal mixed curved reference coordinates.The 3D equilibrium relations and the 3D Fourier heat conduction equation for spherical shells are coupled and they trivially can be simplified in those for plates and cylindrical panels.The exponential matrix methodology is used to find the solutions of a full coupled model based on coupled differential relations with respect to the thickness coordinate.The analytical solution is based on theories of simply supported edges and harmonic relations for displacement components and sovra-temperature.The sovra-temperature magnitudes are directly applied at the outer faces through static state hypotheses.As a consequence,the sovra-temperature description is assumed to be an unknown variable of themodel and it is calculated in the sameway as the three displacements.The final systemis based on a set of coupled homogeneous differential relations of second order in the thickness coordinate.This system is reduced in a first order differential relation system by redoubling the number of unknowns.Therefore,the exponential matrix methodology is applied to calculate the solution.The temperature field effects are evaluated in the static investigation of shells and plates in terms of displacement and stress components.After an appropriate preliminary validation,new benchmarks are discussed for several thickness ratios,geometrical data,lamination sequences,materials and sovra-temperature values imposed at the outer faces.Results make evident the accordance between the uncoupled thermo-mechanical model and this new full coupled thermo-mechanical model without the need to separately solve the Fourier heat conduction relation.Both effects connected with the thickness layer and the related embedded materials are included in the conducted thermal stress analysis.

Study on Physiological Characteristics of Three Different Cold-resistant Tomato Strains

[Objective]The aim was to study cold-resistant indexes and physiological characters of three different cold-resisitant tomato strains selected under natural conditions. [Method]With 3-4 weeks tomato seedlings as tested materials,through simulating external environment conditions by the cold treatment in lab,the survival ratio and growth status of seedlings were identified; by studying the morphological change of in vitro leaves after cold treatment and determining the relative conductivity,the cold-resistant degree of different tomato strains was identified and the correlation between conductivity and survival rate was analyzed; the variation of soluble sugar and praline content in plant of tomato was determined under the condition of cold stress. [Result]The results showed that leaf morphological changes,size of conductivity and growth status of different tomato strains after cold treatment have significant differences; the variation of soluble sugar contents in plant has significant differences,while the variation of proline content has no significant differences. [Conclusion]There is a certain correlation between conductivity and survival rate under cold treatment conditions,and plant cold tolerance is related to accumulation of soluble sugar content.

CO_2, H_2O exchange and stomatal regulation of regenerated Camptotheca acuminata plantlets during ex vitro acclimatization

For finding the changes in CO2, H20 exchange and their stomatal regulation during ex vitro acclimatization of regenerated Camptotheca acuminata plantlets, the net photosynthesis rate （Pn）, respiration rate （Ro）, light compensation point （Lc） and light saturation point （Ls）, transpiration rate （Tr）, stomatal conductance （gs） and water use efficiency（WUE） were measured during 37 days of ex vitro acclimatization. The results showed that Pn sharply increased until 29 days, then slightly decreased. A substantial decrease in Lc and a substantial increase of Ls in the former two weeks were observed, indicating the light regime enlargement for effective leaf photosynthesis. Tr and gs abruptly decreased during the first week then linearly increased until 29days ex vitro acclimatization, reflecting the strong regulation effect of stomata on water changes of ex vitro acclimating plantlets. Stomatal regulation effect on CO2 exchange was different from that on water exchange, i.e. P, was almost independent of gs during the first week, while P. was significantly correlated with gs thereafter （i.e. dual patterns）. Different from dual patterns of gs-Pn relation, the Tr monotonously linearly increased with gs. Furthermore, WUE was almost independent on gs during the first week, while a marked decreasing tendency with gs was found thereafter. At the beginning of the acclimatization, WUE was mainly determined by photosynthetic capacity, while transpiration becomes a main determinant factor for WUE from 7 to 37 days＇ acclimatization.

Study of Ultra-drying on Vigor and Physiological Characteristics of Lespedeza bicolor Seeds

Ultra-drying (in a desiccator with silica gel) and accelerated aging (50 oC, 30 d) of Lespedeza bicolor seeds from the arid and semiarid areas of northwest China were studied. The results showed that in the moisture content of seed ( 43?70 g/kg), germination percentage and vigor indices had no significant differences; ultra-dried seeds had a stronger anti-aging ability than those with natural drying, and the best MC for the storage was 43 g/kg. Therefore, it was feasible to store L. bicolor seeds with ultra-dried moisture content.

Preparation and characterization of LSO-SDC composite electrolytes

The properties of LSO-SDC composite electrolytes prepared by the mixed powder with different LSO/SDC mass ratios were studied. The apatite-type lanthanum silicates La10Si6O27（LSO） and Sm0.2Ce0.8O1.9（SDC） were synthesized via sol-gel process and glycine-nitrate process（GNP）, respectively. The phase structure, microstructure, relative density, thermal expansion properties and oxygen ion conductivity of the samples were investigated by means of techniques such as X-ray diffraction（XRD）, scanning electron microscopy（SEM）, Archimedes method, dilatometer, and AC impedance spectroscopy. The results showed that SDC addition to the samples could enhance the density of the samples. However, the LSO-SDC composite electrolyte sintered at 1550 oC was over sintering when the SDC content was 50 wt.%. At the lower content of SDC（0–10 wt.%）, the decrease of conductivity was predominantly attributed to the reducing concentration of carriers. However, the conductivities of the composite electrolytes increased with the increasing SDC content（10 wt.%–40 wt.%） because of the enhanced percolation of highly conductive SDC component in the microstructure of composite electrolytes. In addition,the dependence of conductivity on p（O2） showed that LSO-SDC composite electrolytes were stable in the examined range of p（O2）.