994 resultados para Bai f, Lazare de, 1496?-1547.
Resumo:
The crack patterns generated in a real ceramic plate and in a plate stacked by ceramic slabs under quenching are experimentally studied. The results here reveal that there are some distinct differences between the two crack patterns. The reasons that caused the differences are the size and boundary effects of the slabs. These crack patterns are very useful to understand the failure mechanisms of ceramic materials in thermal shock.
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The catastrophic failure of heterogeneous brittle materials under impact loading is not fully understood. To describe the catastrophic failure behavior of heterogeneous brittle materials under impact loading, an elasto-statistical-brittle (ESB) model is proposed in this paper. The ESB model characterizes the disordered inhomogeneity of material at mesoscopic scale with the statistical description of the shear strength of mesoscopic units. If the applied shear stress reaches the strength, the mesoscopic unit fails, which causes degradation in the shear modulus of the material. With a simplified ESB model, the failure wave in brittle material under uni-axial compression is analyzed. It is shown that the failure wave is a wave of strain or particle velocity resulted from the catastrophic fracture in an elastically stressed brittle media when the impact velocity reaches a critical value. In addition, the failure wave causes an increase in the rear surface velocity, which agrees well with experimental observations. The critical condition to generate failure wave and the speed of failure wave are also obtained.
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The output characteristics of micro-solar cell arrays are analyzed on the basis of a modified model in which the shunt resistance between cell lines results in current leakage. The modification mainly consists of adding a shunt resistor network to the traditional model. The obtained results agree well with the reported experimental results. The calculation results demonstrate that leakage current in substrate affects seriously the performance of GaAs micro- solar cell arrays. The performance of arrays can be improved by reducing the number of cells per line. In addition, at a certain level of integration, an appropriate space occupancy rate of the single cell is recommended for ensuring high open circuit voltages, and it is more appropriate to set the rates at 80%-90% through the calculation.
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11.1 1400m 15 2 35 38 5 20 1.2 2200 m 2200 ( CJ ) 2200 m 2200 m 2200 (Cody ) 2800 3200 (Cody ) 2138 421 990 We have collected the specimens and gotten the biodiversity datas of BaiShuihe Nature Reserve in Peng Zhouanalysed the datasthe results as follows1. Diversity of the plant community along altitudinal gradient1.1 diversity of the plant communities along altitudinal gradientFrom 1400m to 3900m at Baishuihe Nature Reserve, 52 plots were investigatedwith an interval 100m in altitude diversity and diversity of plant communitiesand their variety along altitudinal gradient were studied. The results showed that indifferent successional layers of trees, richness and diversity decreased linearly withthe increase of altitude. But shrub and herb layers dont decrease linearly with theincrease of altitude. Tree species decreased from 15 species at 1400m so only 2species at timberline. Shrub and herb species decreased from 35 and 38 species at2000m to 5 and 20 species at 3800m respectively. Tree species are replacedobviously with the increase of altitude It shows that altitude includes manyenvironmental facts, which infect the distribution, structure and diversity of plant population.1.2 The variety of diversity along altitudinal gradient.The entironment changed obviously near 2200m according to our research. Forsimilarity(CJ) between neighboring plots above 2200m is larger than wich below it.It shows that below 2200mthe neighboring plots has more same speciesand thehabitats of neighboring plots has more similarity. Above 2200 is the other way round.The plant communites have higher species richness and species turnoverlargestly between neighboring plots because of the disturbance from humanity at lowaltitude. Between 2800m and 3200m species turnover not so obviously because ofmore Rhododendron live there.We should think over species and the types of plant communities effect thevariety of diversity along altitude gradient. Use more biodiversity indexs and fromseveral aspects to understand the variety of diversity along altitudinal gradient.2.Origin and characteristic features of Bai Shuihe Nature Reserve990 species of wild seed plants (belonging to 421 generas in 138 families) inthe floristic region of Bai Shuihe Nature Reserve were reported here. The statisticsand comparatively intensive analysis at generic and familiar levelss. Based on thestatisticsthe results show that both temperate and tropical distribution types areacounted for considerable proportion of the totalbut formal is a little moreimportant than the later. The North Temperate and E.Asia-N.America disjunctedpatterns are more concentrated in this area. These may be considered as thecharacteristic features of Bai Shuihe Nature Reserve flora, while many of them arearchaic and relic elements. According to above datathe floristic region of BaiShuihe Nature Reserve may be considered as a typical region in Chinese flora. Alsothe flora of Bai Shuihe Nature Reserve are originated since ancient time as a wellconserved Arctic-Tertiar flora.
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IEECAS SKLLQG
Resumo:
IEECAS SKLLQG
