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Abundance and Dynamics of Soil Labile Carbon Pools Under Different Types of Forest Vegetation

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Pedosphere 2006年第4期16卷 505-511页

作者： JIANG pei-Kun xu Qiu-Fang Zhejiang Forestry College Lin＇an 311300 （China）

Soil organic matter (SOM) in forest ecosystems is not only important to global carbon (C) storage but also to sustainable management of forestland with vegetation types, being a critical factor in controlling the quantity and dynamics of SOM. In this field experiment soil plots with three replicates were selected from three forest vegetation types: broadleaf, Masson pine (Pinus massoniana Lamb.), and Chinese fir (Cunninghamia lanceolata Hook.). Soil total organic C (TOC), two easily oxidizable C levels (EOC1 and EOC2, which were oxidized by 66.7 mmol L-1 K_2Cr_2O_7 at 130-140℃and 333 mmol L-1 KMnO4 at 25℃, respectively), microbial biomass C (MBC), and water-soluble organic C (WSOC) were analyzed for soil samples. Soil under the broadleaf forest stored significantly higher TOC (P (?) 0.05). Because of its significantly larger total soil C storage, the soil under the broadleaf forest usually had significantly higher levels (P (?) 0.05) of the different labile organic carbons, EOC1, EOC2, MBC, and WSOC; but when calculated as a percentage of TOC each labile C fraction of the broadleaf forest was significantly lower (P (?)0.05) than one of the other two forests. Under all the three vegetation types temperature as well as quality and season of litter input generally affected the dynamics of different organic C fractions in soils, with EOC1, EOC2, and MBC increasing closely following increase in temperature, whereas WSOC showed an opposite trend.

关键词： dynamics forest soil labile organic C total organic C vegetation system

Numerical and Experimental Study of Blockage Effect Correction Method in Towing Tank

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China Ocean Engineering 2019年第5期33卷 522-536页

作者： GUO Chun-yu xu pei WANG Chao KAN Zi College of Shipbuilding Engineering Harbin Engineering University Harbin 150001 China Scool of Aeronautic Science and Engineering Beihang University Beijing 100191 China

When a ship model test is performed in a tank, particularly when the tank is small and the ship model is relatively large, the blockage effect will inevitably occur. With increased ship model scale and speed, the blockage effect becomes more obvious and must be corrected. In this study, the KRISO 3600 TEU Container Ship (KCS) is taken as a model and computational fluid dynamics techniques and ship resistance tests are applied to explore the mechanism and correction method of the blockage effect. By considering the degrees of freedom of the sinkage and trim, the resistance of the ship model is calculated in the infinite domain and for blockage ratios of 1.5%, 1.8%, 2.2%, and 3.0%. Through analysis of the free surface, pressure distribution, and flow field around the ship model, the action law of the blockage effect is studied. The Scott formula and mean flow correction formula based on the average cross sectional area are recommended as the main correction methods, and these formulas are improved using a factor for the return flow velocity correction based on comparison of the modified results given by different formulas. This modification method is verified by resistance test data obtained from three ship models with different scale ratios.

关键词： blockage effect ship model resistance blockage ratio KCS ship CFD

Experimental research on the influence of two cultivation practices on rainfall runoff-and (sandy and muddy) sediment-generating processes in purple soil environment

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Chinese Journal Of Geochemistry 2008年第4期27卷 370-376页

作者： xu pei WANG Yukuan FU Bin Institute of Mountain Hazards and Environment Chinese Academy of Sciences Chengdu 610041 China Graduate University of the Chinese Academy of Sciences Beijing 100049 China

Rainfall simulations have been conducted to study the soil erosion process of purple soil in two cultiva-tion practices—contour cultivation and downslope cultivation. Results showed that under the two cultivation prac-tices,the surface runoff can be described by the logarithmic function formula. In the initial period of rainfall,the amount of runoff increased with the rainfall duration and 20 minutes later it became relatively constant. The chang-ing process of soil erosion rate may be described by the logarithmic function formula. The erosion rate increased with the rainfall duration and 20 minutes later it also became constant. Under downslope cultivation condition,the soil erosion rate increased more significantly than that under contour cultivation condition in the case of gentle rain-fall intensity,and there is no obvious difference in erosion rate for downslope cultivation and contour cultivation practices. However,with increasing rainfall intensity the soil erosion rate under the downslope cultivation condition could be more than 30 times that under the contour cultivation condition. But this kind of difference would be re-duced to some extent in the case of heavy rain.

关键词：降雨量模拟土壤侵蚀径流等高线

Assessment of the Performance of WEPP in Purple Soil Area with Simulated Rainfall Experiments

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Journal of Mountain Science 2012年第4期9卷 570-579页

作者： FU Bin WANG Yukuan xu pei YAN Kun Key Laboratory of Mountain Hazards and Earth Surface Process ChineseAcademy of SciencesChengdu 610041China Institute of Mountain Hazards and Environment Chinese Academy of SciencesChengdu 610041China

The water erosion prediction project （WEPP） model is a popular water erosion prediction tool developed on the basis of the physical processes of water erosion. Although WEPP has been widely used around the world, its application in China is still insufficient. In this study, the performance of WEPP used to estimate the runoff and soil loss on purple soil （Calcaric Regosols in FAO taxonomy） sloping cropland was assessed with the data from runoff plots under simulated rainfall conditions. Based on measured soil properties, runoff and erosion parameters, namely effective hydraulic conductivity, inter-rill erodibility, rill erodibility, and critical shear stress were determined to be 2.68 mm h-1, 5.54 x l0^6 kg s-1 m-4, 0.027 s m-1 and 3-5 Pa, respectively, by using the recommended equations in the WEPP user manual. The simulated results were not good due to the low Nash efficiency of 0.41 for runoff and negative Nash efficiency for soil loss. After the four parameters were calibrated, WEPP performed better for soil loss prediction with a Nash efficiency of 0.76. The different results indicated that the equations recommended by WEPP to calculate parameters such as erodiblity and critical shear stress are not suitable for the purple soil areas, Sichuan Province, China. Although the predicted results can be accepted by optimizing the runoff and erosion parameters, more research related to the determination of erodibility and critical sheer stress must be conducted to improve the application of WEPP in the purple soil areas.

关键词： WEPP Soil erosion Simulated rainfall Purple soil Erodibility

Microclimate regulation efficiency of the rural homegarden agroforestry system in the Western Sichuan Plain,China

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Journal of Mountain Science 2019年第3期16卷 516-528页

作者： LIU Qin PENG pei-hao WANG Yu-kuan xu pei GUO Ying-man College of Earth Sciences Chengdu University of Technology Institute of Mountain Hazards and Environment Chinese Academy of Sciences University of Chinese Academy of Sciences

Traditional rural homegarden agroforestry systems(referred to as homegarden) in the Western Sichuan Plain of China are often referred to as "Linpan" in Chinese. These homegardens are usually composed of farm houses, trees, bamboos, and small patches of land for flowers, fruits and vegetables. Over the Western Sichuan Plain’s area of approximately 18,800 km^2, there were more than 200,000 homegardens, accommodating 72.5% of the region’s rural population. As a unique local, cultural, and ecological resource, homegardens continuously support peasant households with provisioning, regulation, and landscape ecosystem services. This study combined low height remote sensing used unmanned aerial vehicle(UAV) photography, field investigation, and instrument monitoring. We try to identify the composition and structural characteristics of homegardens, as well as climatic regulation effects of the different types of homegardens. Temperature data were collected both for summer(June to August 2016) and winter(December 2016 to February 2017). The result shows that:(1) the average area of homegardens was 0.67 ha(sizes ranging from 0.16 ha to 1.24 ha), and with vegetation coverage 43.5%-76.9%(including 310 plant species).(2)In comparision with outside the homegardens, the average temperature inside the homegardens was significantly lower in summer(approximately 0.31 ℃-0.90 ℃). Although, the lowest summer temperature was differentiatee in between 13:30-16:00. Especially, the thermal effects of the home gardens were ranged from 2.00℃-2.65℃ at high temperatures(≥30℃).(3) The cooling effect of homegardens were positively correlated(pX_4>X_5>X_2>X_1.(4)This study indicates the major role of homegardens for climate regulation and energy efficiency, providing suggestions for homegarden transformation and constructio

关键词： Homegarden Linpan Western Sichuan Plain Climate regulation Energy saving and emission reduction

Medium optimization for enhanced production of cytosine-substituted mildiomycin analogue (MIL-C) by Streptoverticillium rimofaciens ZJU 5119

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Journal of Zhejiang University-Science B(Biomedicine & Biotechnology) 2008年第1期9卷 77-84页

作者： Dan YE Zhi-nan xu pei-lin CEN Department of Chemical and Biochemical Engineering Zhejiang University Hangzhou 310027 China

Cytosine-substituted mildiomycin analogue （MIL-C） was produced effectively by supplementing cytosine into the culture of Streptoverticillium rimofaciens. In order to improve the yield of MIL-C, statistically-based experimental designs were applied to optimize the fermentation medium for S. rimofaciens ZJU 5119. Fifteen culture conditions were examined for their significances on MIL-C production using Plackett-Burman design. The Plackett-Burrnan design and one-variable-at-a-time design indicated that glucose and rice meal as the complex carbon sources, and peanut cake meal and NH4NO3 as the complex nitrogen sources were beneficial for MIL-C production in S. rimofaciens ZJU 5119. The results of further central composition design （CCD） showed that the optimal concentration of glucose, rice meal and peanut cake meal were 18.7 g/L, 64.8 g/L and 65.1 g/L, respectively. By using this optimal fermentation medium, the MIL-C concentration was increased up to 1336.5 mg/L, an approximate 3.8-fold improvement over the previous concentration （350.0 mg/L） with un-optimized medium. This work will be very helpful to the large-scale production of MIL-C in the future.

关键词： Cytosine-substituted mildiomycin analogue (MIL-C) Plackett-Burman design Response surface methodology Streptoverticillium rimofaciens Nucleoside antibiotic

Ince-Strutt Stability Charts for Ship Parametric Roll Resonance in Irregular Waves

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China Ocean Engineering 2017年第4期31卷 447-457页

作者： ZHANG Xiao YANG He-zhen XIAO Fei xu pei-ji National Key Laboratory on Ship Vibration &Noise China Ship Development and Design Center State Key Laboratory of Ocean Engineering School of Naval Architecture.Ocean and Civil EngineeringShanghai Jiao Tong University School of Civil and Environmental Engineering Nanyang Technological University

Ince-Strutt stability chart of ship parametric roll resonance in irregular waves is conducted and utilized for the exploration of the parametric roll resonance in irregular waves. Ship parametric roll resonance will lead to large amplitude roll motion and even wreck. Firstly, the equation describing the parametric roll resonance in irregular waves is derived according to Grim’s effective theory and the corresponding Ince-Strutt stability charts are obtained. Secondly, the differences of stability charts for the parametric roll resonance in irregular and regular waves are compared. Thirdly, wave phases and peak periods are taken into consideration to obtain a more realistic sea condition. The influence of random wave phases should be taken into consideration when the analyzed points are located near the instability boundary. Stability charts for different wave peak periods are various. Stability charts are helpful for the parameter determination in design stage to better adapt to sailing condition. Last, ship variables are analyzed according to stability charts by a statistical approach. The increase of the metacentric height will help improve ship stability.

关键词： parametric instability parametric rolling multi-frequency irregular waves Ince-Strutt stability chart

SHRIMP zircon U-Pb dating and its geological significance of Chibaisong gabbro in Tonghua area,Jilin Province,China

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Science China Earth Sciences 2006年第4期49卷 368-374页

作者： pei Fuping xu Wenliang YANG Debin ZHAO Quanguo College of Earth Sciences Jilin University Changchun 130061 China College of Earth Sciences Jilin University Changchun 130061 China College of Earth Sciences Jilin University Changchun 130061 China College of Earth Sciences Jilin University Changchun 130061 China

SHRIMP zircon U-Pb dating for Chibaisong No.1 gabbro in the Tonghua area, Jilin Prov- ince, is discussed in the paper. The cathodoluminescence (CL) images of the zircons indicate that they can be divided into two major types, i.e. euhedral-subhedral one with striped absorption and round one with obvious oscillatory zoning rims. The dating results of the zircons suggest that Chibai- song gabbro in the Tonghua area was formed at 134±7Ma—the Early Cretaceous. The concordia ages of 2497±13Ma, 787±35Ma, 321±10Ma, 217±11Ma of zircons imply that the Tonghua area might geologically be located in the convergent region of the Yangtze Block (YB) and the North China Block (NCB) in the early Mesozoic and the zircons should be caught during magma intrusion. The existence of the Early Cretaceous basic dyke swarm in the Tonghua area shows that an intensive extensional environment occurred in the Early Cretaceous. It is suggested that the magmatism and lithospheric extension in the Tonghua area should be related to the subduction of the Pacific plate.

关键词： zircon, gabbro, SHRIMP U-Pb dating, Tonghua area.

“PALPATION BY IMAGING”:MAGNETIC RESONANCE ELASTOGRAPHY

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Chinese Medical Sciences Journal 2006年第4期21卷 281-286页

作者： Lei xu pei-yi Gao Imaging Center of Neuroscience Beijing Tiantan Hospital Capital University of Medical Sciences Beijing 100050

Elasticity is an important physical property of human tissues. There is a tremendous difference in elasticity between normal and pathological tissues. Noninvasive evaluation of the elasticity of human tissues would be valuable for clinical practice. Magnetic resonance elastography(MRE)is a recently developed noninvasive imaging technique that can directly visualize and quantitatively measure tissue elasticity. This article reviewed the MRE technique and its current status.

关键词： magnetic resonance imaging elasticity tissue characterization