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1

Spatial and seasonal variations in the planktonic ciliate community and its relationship with environmental factors in Daya Bay, the South China Sea

Wu F., Huang J., Qi Z., Huang H.

Oceanological and Hydrobiological Studies

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2017

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Vol. 46, No. 2

212--222

EN

Planktonic ciliate composition, abundance and its response to environmental change were investigated during four seasons (winter of 2013, spring, summer and autumn of 2014) in Daya Bay, the South China Sea. A total of 41 species belonging to eight orders were identified, 14 of which were dominant. Planktonic ciliate communities showed a distinct seasonal pattern in ciliate abundance and a clear seasonal shift in the taxonomic composition. The largest number of ciliate species occurred in summer, whereas the highest abundance peaked in spring, mainly due to oligotrichids. In terms of spatial distribution, ciliate species were abundant in the area of artificial reefs, and ciliate abundance was higher in the Dapeng Cove aquaculture area and lower at the Daya Bay Nuclear Power Station. Clustering analysis demonstrated that the seasonal variations of the ciliate community structure were more obvious than spatial variations. Multivariate and univariate analyses illustrated that ciliate abundance was significantly correlated with the water nutrient level and chlorophyll-a concentration, temperature, salinity and dissolved oxygen. Moreover, the dominant abiotic environmental factors affecting the spatial pattern of ciliate communities varied between seasons.

2

Soil Fauna Significantly Contributes to Litter Decomposition at Low Temperatures in the Alpine/Subalpine Forests

Tan B., Wu F., Yang W., Xu Z., Zhang L., Liu Y.

Polish Journal of Ecology

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2015

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Vol. 63, nr 3

377--386

EN

Decomposition of litter is a crucial process in terrestrial ecosystems, determining global carbon budget and nutrient turnover. Soil faunas have been shown to accelerate the rates of litter decomposition and nutrient cycling in terrestrial ecosystems. Litter decomposition has recently been observed in winter in alpine/subalpine ecosystems, but the contribution of soil fauna to the decomposition process is not clear. Field experiment using litterbags was conducted in order to quantify the contributions of soil fauna to mass losses of fir (Abies faxoniana) and birch (Betula albosinensis) litters during a freeze-thaw season in three representative alpine/subalpine forests. The litterbags of mesh sizes 0.02 mm, 0.125 mm, 1.0 mm and 3.0 mm were placed on the forest floor in October 2010, and collected after each of the three stages of the freeze-thaw season: OF, the onset of freezing stage (26 October to December 31); DF, the deeply frozen stage (1 January to 4 March 2011); and TS, the thawing stage (5 March to 30 April 2011) over the entire 2010/2011 winter. Over the whole freeze-thaw period, the mass losses of fir litter were 11–12% (0.02 mm), 12–13% (0.125 mm), 14–15% (1.0 mm) and 17–19% (3.0 mm), and that of birch litter were 10–13% (0.02 mm), 12–15% (0.125 mm), 13–18% (1.0 mm) and 17–22% (3.0 mm), respectively, depending on the altitude. The mass losses caused by microfauna, mesofauna and macrofauna for the fir litter accounted for 6–9, 12–13 and 22–25%, respectively and that for the birch litter accounted for 8–11, 13–15 and 25–27%, respectively. Furthermore, the contributions of soil fauna to mass loss showed an increasing trend with increasing body size regardless of species at three stages of the freeze-thaw period. These results suggest that soil fauna contributes strongly to litter decomposition during the freeze-thaw period in alpine/subalpine regions.

3

The Static Unbalance Analysis and Its Measurement System For Gimbals Axes of an Inertial Stabilization Platform

Yang H., Zhao Y., Li M., Wu F.

Metrology and Measurement Systems

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2015

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Vol. 22, nr 1

51--68

EN

To reduce the influence of the static unbalance on an infrared missile guidance system, a new static unbalance measure system for the gimbals axes has been developed. Considering the coupling effects caused by a mass eccentricity, the static balance condition and measure sequence for each gimbal axis are obtained. A novel static unbalance test approach is proposed after analyzing the dynamic model of the measured gimbal axis. This approach is to drive the measured gimbal axis to do sinusoidal reciprocating motion in a small angle and collect its drive currents in real time. Then the static unbalance of the measured gimbal axis can be obtained by the current multi-cycle integration. Also a measuring system using the proposed approach has been developed. A balanced simulator is used to verify the proposed approach by the load and repeatability tests. The results show the proposed approach enhances the efficiency of the static unbalance measurement, and the developed measuring system is able to achieve a high precision with a greater stability.

4

One cabin equipment location method based on the visibility human-factor potential field

Ge Z., Wu F., Yang Y., Luo X.

Eksploatacja i Niezawodność

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2015

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Vol. 17, no. 2

236--242

EN

The visibility is the basic condition for cabin equipment location. For the description of human, object and obstacle, the humanfactor potential field concept is proposed in this paper, concluding the visibility potential field, the reachability potential field. The cabin equipment layout problem is modeled based on the basic visibility potential field model. The optimal layout optimization method is studied based on the particle swarm optimization (PSO) algorithm by natural selection. Finally, the applicability of the proposed idea is illustrated by numerical studies.

PL

Widoczność jest podstawowym warunkiem przy projektowaniu rozmieszczenia przyrządów pokładowych. W przedstawionej pracy zaproponowano pojęcie potencjałowego pola czynnika ludzkiego (human-factor potential field, HFPF), które służy do opisu czynnika ludzkiego, przedmiotów oraz przeszkód. HFPF obejmuje pojęcia potencjałowego pola widoczności oraz potencjałowego pola dostępu. Problem umiejscowienia elementów wyposażenia kabiny zamodelowano na podstawie podstawowego modelu potencjałowego pola widoczności. Metodę optymalizacji rozmieszczenia elementów wyposażenia badano w oparciu o algorytm optymalizacji rojem cząstek (PSO), metodą naturalnej selekcji. Zastosowanie proponowanej koncepcji zilustrowano na przykładzie badań numerycznych.

5

Soil fauna community dynamics during soil thawing period in the subalpine and alpine forests of Western China

Wu F., Yang W., Yang Y., Wang A., Tan B.

Polish Journal of Ecology

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2012

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Vol. 60, nr 4

755--766

EN

The frequently changed temperature could have great effects on soil fauna community during soil thawing period in cold areas. Therefore, soil faunas were investigated in both the soil organic layer (OL) and mineral soil layer (ML) in the primary fir (Abies faxoniana) forest (PF), fir and birch (Betula albosinensis) mixed forest (MF) and secondary fir forest (SF) in the eastern Qinghai–Tibet Plateau every ten days between March 5 and April 25, 2009. Soil macrofauna was picked up by hand in the fields. Mesofauna was collected and separated from the soil samples by Baermann and Tullgren methods, respectively. The dominated species of macrofauna belonged to Coleoptera and Diptera at the early stage of soil thawing, and to Coleoptera, Diptera, Araneae and Hymenoptera at the later stage. However, the dominated species of mesofauna belonged to Nematode, Collembola, and Acari in the whole soil thawing. The density, number of taxa, and diversity index of soil fauna showed significant change with temperature fluctuations and reached an obvious peak when soil temperatures rising above 0[degrees]C. The density and number of taxa of macrofauna in both the OL and ML were the lowest on March 5 in the three forests, but the density of mesofauna in both the OL and ML was the highest on March 25, except for the ML in the PF. These results implied that soil fauna community was sensitive to temperature fluctuations, which is important in understanding the ecological processes in the winter–spring transitional period.

6

Relationship between groundwater depth and pattern of net primary production in oasis-desert ecotone

Wu F., Deng J., Li T., Wang G., Wei X., Zhao C.

Polish Journal of Ecology

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2010

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Vol. 58, nr 4

681-692

EN

Pattern of plant biomass and net primary production was investigated in two localities (Minqin and Linze) of oasis-desert ecotone (ODE) in Northwest China, in order to recognize the spatial and temporal variability of vegetation under same regional climate with different groundwater depth. The average depth to groundwater was over 14.02 m at Minqin - marked further as DG (deep groundwater) and about 4.96 m at Linze - marked further as SG (shallow groundwater). We have measured plant biomass and net primary productivity (NPP) across species, three times per year for three consecutive years, in six plots along Minqin and Linze oasis-desert ecotone (further marked as DG and SG ODE), respectively. Our results showed that DG and SG ODEs had different growth responses to different groundwater depths. DG ODE exhibited higher inter-annual variation in annual NPP (ranged from 0.18 to 9.30 g m[^-2]) than did SG ODE (ranged from 0.42 to 17.99 g m[^-2]). Decrease of groundwater depth had apparently altered the seasonality of productivity in DG ODE systems, where precipitation in summer maintained plant growth, while ODE with high groundwater depth tended to have higher spring NPP in SG ODE. Spatial and temporal heterogeneity of NPP at the scale of our measurements was significantly greater in DG ODE than in SG ODE. SG ODE tended to support higher NPP than did DG ODE. In addition, the groundwater depth strongly influenced spatial and temporal heterogeneity of NPP in the desert ecosystems. Clearly, the desert ecosystem with higher groundwater depth is more stable and more resistant to long-term drought or climate shifts in arid regions. These investigations and quantitatively analysis are very significant for the execution of conservation and restoration in arid ecosystems.

7

Ergonomics Hazards Analysis of Linemen’s Power Line Fixing Work in China

Yu M., Sun L., Du J., Wu F.

International Journal of Occupational Safety and Ergonomics

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2009

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Vol. 15, No. 3

309--317

EN

This study used qualitative and quantitative methods, such as OWAS (Ovako working posture analysis system) and behavior observation, to analyze musculoskeletal disorder (MSD) risk factors of power line fixing work in China. Video-based sampling was used to record and analyze the frequency and posture of on-pole activities. Those key subtasks showed ergonomics characteristics of on-pole fixing tasks. Insulator-fixing was the longest subtask (33% of total working time). Bar-installing was the second longest (26% of total working time). It was evident that bar-installing and insulator-fixing were full of hazardous risks. The action categories of the 2 subtasks were higher than of the other ones. The 2 subtasks were also time-consuming, difficult and induced MSDs. Assistant linemen faced more hazardous factors than chief linemen.