BazTech - Yadda

1

Three-dimensional biomechanical modeling and simulation of trephine cutting cornea for keratoplasty

Su P., Lu D., Deng S., Zhang L., Hao Y., Yang Y.

Acta of Bioengineering and Biomechanics

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2018

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Vol. 20, no. 2

23--33

EN

Trephination is one of the basic operations of keratoplasty, and the biomechanical mechanism of the operation can be revealed based on three-dimensional modeling and simulation of trephine cutting cornea. Methods: Based on the analysis of the physical and biomechanical characteristics of corneal trephination, a three-dimensional numerical model of corneal trephination is built, where the cornea can be simplified to two layers structure including stroma and epithelium, and the trephine cuts the cornea under the vertical motion load and the rotational motion load. A three-dimensional failure criterion of corneal material is proposed based on the yield strength theory. On this basis, trephination simulation is carried out, and the units of corneal material are removed from the model when they meet the defined failure criterion. Results: Under the given parameters including the velocity, the angle and the angular velocity, the trephine force curves, include the linear cutting force and the rotary cutting force are obtained, and show the change of the forces with displacement during the process of trephination simulation. The maps of the equivalent stress show the destruction and deformation of the cornea. Then, the experiment of robotic trephination is carried out under the same parameters and the effectiveness of the simulation is evaluated. Conclusions: Based on mechanics theory and finite element method, the process of trephine cutting cornea has been reproduced, and the interaction mechanism is revealed, which lays the foundation for the development of real-time simulation and virtual system of the corneal surgery.

2

Partial Discharge Pattern Recognition of Medium-Voltage Switchgear Based on Association Rules Mining

Hao Y., Huang C., Zheng W.

Przegląd Elektrotechniczny

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2013

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R. 89, nr 4

176-179

EN

In the paper, a new partial discharge pattern recognition approach based on association rules mining is developed. Some statistical parameters are extracted from the sampled transient earth voltage data and classic Apriori algorithm is employed to mine the association rules between those parameters and the corresponding fault types. Moreover, using other experimental data obtained in the laboratory, the method is validated and made comparison with two conventional methods.

PL

W artykule opisano metodę wykrywania wyładowań niezupełnych, poprzez wyznaczenie reguł powiązanych z wystąpieniem tych wyładowań i ich wyszukiwanie. Dzięki analizie statystycznej danych dotyczących stanów nieustalonych napięcia oraz zastosowaniu algorytmu apriori, określono zasady powiązane z wystąpieniem zjawisk. Skuteczność działania rozwiązania została potwierdzona wynikami badań eksperymentalnych, które następnie porównano z dwoma konwencjonalnymi metodami.

3

Effect of 5 years long cessation of grazing on methane uptake in a semi-arid grassland

Zhou X., Hao Y.

Polish Journal of Ecology

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2010

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Vol. 58, nr 4

801-804

EN

Grazing exerts a key role in nutrient cycling in grassland ecosystems, however, little is known about the effects of short-term enclosure on methane (CH4) fluxes in a semi-arid steppe biome like this of Inner Mongolia. CH4 fluxes were measured in the Leymus chinensis (Trin) Tzvel. grassland using static chamber and gas chromatography (GC). Measurements were carried out twice per month over a growing season in 2004 at the two sites (one fenced since 1999 (UG99) and the other subjected to freely grazing (FG)). All CH4 fluxes were positive, indicating that this grassland functioned as the active atmospheric CH4 uptakes. During this period, the UG99 site (57.6 [plus or minus] 6.7 [mu]g C m[^-2] h[^-1]) had significantly higher mean CH4 uptake in comparison to the FG site (37.0 [plus or minus] 6.3 [mu]g C m[^-2] h[^-1]). A significant liner negative correlations between CH4 uptake and soil moisture (0.5 cm) at the both sites were found (P <0.05). The results indicated that short-term enclosure was helpful to improve CH4 uptake in this area.

4

Carbon storage of cycad and other gymnosperm ecosystems in China: implications to evolutionary trends

Ma Y., Jiang H., Wang B., Zhou G., Yu S., Peng S., Hao Y., Wei X., Liu J., Yu Z.

Polish Journal of Ecology

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2009

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Vol. 57, nr 4 (2

635-646

EN

Cycads are an ancient lineage of plants that originated in the Permian, which are vital to the interpretation of plant ecology. The evidence in the fossil records indicates that the morphological and anatomical features of cycads are remarkably similar to the extant taxa, which has been instrumental in our understanding the connections between the early origins of seed plants and their present-day counterparts. The cycad ecosystem is an important vegetation type throughout geological time. Research on the ecological function of the cycad plays a significant role in the study of evolutionary ecology. In this study, we investigated the biomass, productivity and total carbon storage (total of vegetation, litter, and soil carbon) of cycad (Cycas panzhihuaensis L. Zhou et S.Y. Yang) ecosystems in the National C. panzhihuaensis Reserve of China (latitude 26[degrees]37', longitude 101[degrees]35', at 1635 m altitude) by applying the site-standard tree sampling harvest. Cycads are considered to be rare and endangered species, and are in the list of key protected wild plants in the world. The National C. panzhihuaensis Reserve is in Southwestern China, which area approximately 1358 ha, growing approximately 20 000 C. panzhihuaensis individuals. 20 sample plots, each 5 x 5 m were established in the spring of 2006. The mean height of cycads within the stand was 0.44 m and the mean basal diameter was 23.2 cm. The biomass and productivity data for other communities was compiled from references published over the past 20 years throughout China. The biomass and productivity of cycad ecosystems (8.102 [plus or minus] 6.880 t C ha[^-1] and 1.183 [plus or minus] 0.975 t C ha[^-1] yr[^-1], respectively) are smaller than tree fern (Alsophila spinulosa (Wall. ex Hook.) R. M. Tryon) or gymnosperm (Pinaceae, Cupressaceae or Taxodiaceae for representative) ecosystems. The community biomass of Pinaceae-, Cupressaceae- or Taxodiaceae-dominated ecosystems are 6.8, 5.4, and 5.3 times larger than the cycad ecosystem, respectively. The productivity of each is 2.3, 2.8 and 3.8 times larger than the cycad ecosystem. Cycad is an ancient dioecious plant. However, the results show that the differences between the biomass of male and female cycads, as well as the productivity, are not significant.