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Search Results: 1 - 10 of 56813 matches for " LOU Yan-Jing "
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Change in floristic composition and species diversity of plant community along environment gradient in Honghe National Nature Reserve, China

LOU Yan-Jing,ZHAO Kui-Yi,MA Ke-Ping,

生态学报 , 2007,
Abstract: 以洪河自然保护区两类典型湿地——河漫滩湿地与碟形洼地湿地的植物群落为研究对象,探讨其物种组成及物种多样性的梯度变化规律。结果表明,由沼泽至岛状林的梯度上:(1)各群落建群种、优势种和伴生种的种类及其优势度,地表覆盖藓类等组成特征均变化明显;(2)群落的物种丰富度呈逐渐增加格局,丰富度指数分别为26、41、51、68和82;(3)群落的α多样性的变化格局与丰富度格局不太一致,Shannon-Wiener多样性与Pielou均匀度的变化格局基本一致,呈不规则"N"型格局,Simpson优势度的变化格局正好与它们相反,呈不规则倒"N"型格局;上述格局的两个"拐点"出现在沼泽化草甸群落和湿草甸群落中;(4)群落的β多样性——相异性系数和Cody指数均呈先降后升的格局,二者的最小值出现在沼泽化草甸群落和湿草甸群落之间,最大值出现在灌丛草甸和岛状林群落之间;研究认为,典型湿地植物群落物种组成和物种丰富度的梯度变化主要于生境的变化有关,α多样性的变化格局主要与生境的变化和优势种的生物学特性有关,β多样性的格局的原因比较复杂,尚需进一步探讨。
The Changes of the Soil Hydrothermal Condition and the Dynamics of C, N after the Mire Tillage

SONG Chang-chun,WANG Yi-yong,YAN Bai-xing,LOU Yan-jing,ZHAO Zhi-chun,

环境科学 , 2004,
Abstract: The wetlands gain increasing attention to its crucial ecological and environmental function. The tillage of the mires in the Sanjiang Plain has played the important role in regulation of the region ecological balance and climate. Prior to tillage, the mean soil temperature of the topsoil (10 cm) in mire from June to September was 12.72 degrees C +/- 4.12 degrees C, distinctly lower than that of the tilled soil, which was 16.71 degrees C +/- 3.81 degrees C. However, the daily mean evaporation of 4.87 mm +/- 3.78 mm in the mire was larger than that of the tilled soil with mean soil temperature of 2.66 mm +/- 3.78 mm from May to September. The alteration of the oxidization-reduction condition and the augment of the soil temperature led to the increases of soil organic matter (SOM) decomposition ratio and the soil respiration flux, the mean soil respiration (CO2) flux (946.36 +/- 195.78) mg x (m2 x h)(-1)] was 6 times larger than that of the mire (153.75 +/- 82.59) mg x (m2 x h)(-1)] from August to September. At the initial stage (5-7a) of the mire tillage, the SOM and the nutrients levels change significantly, but after the 15-20a of continuous cultivation, the SOM loss curve came to a relative stable value. The lessen of the input and strength of the decomposition rate of SOM resulted in the accretion of soil bulk capacity and specific gravity, its changing trend was similar to the changing of the soil organic carbon (SOC) loss.
Characteristics of the soil seed banks and relationships with the vegetation in restored wetlands in Sanjiang Plain, northeast of China

WANG Guo-Dong,L Xian-Guo,JIANG Ming,WANG Ming,ZHAO Kui-Yi,LOU Yan-Jing,

植物生态学报 , 2012,
Abstract: Aims Seed banks are an important source of regenerative material in wetlands. Our objective was to study characteristics of the soil seed banks and relationships with the vegetation in different restoration successional stages. Methods We collected soil seed banks from different depths (0–5 cm, 5–10 cm and rhizomes) from farmed wetland, restored wetland in different successional stages and natural wetland and germinated them under two water regimes (flooded and non-flooded) in a greenhouse. We used quadrats to survey vegetation structure in natural wetland and restored wetlands of different successional stages. Important findings With increased the restoration time, seed bank composition and size increased, and the vegetation community showed succession from a xerophyte-dominated community to a wetland community dominated by Calamagrostis angustifolia. Number of species germinated from the seed banks was 24, 29 and 39, while 21, 25 and 14 species were recorded in the vegetation of in 7-year restored wetland, 14-year restored wetland and natural wetland, respectively. Wetland type, water regime, depth of burial significantly influenced both the species richness and seedling emergence (p < 0.01). Seed density varied with depth so that seed density was higher in 0–5 cm than in 5–10 cm. The seed density in 0–5 cm was four times as that in 5–10 cm in natural wetland while it was just 1.3 times in restored wetland. The similarity between layers was low. More species germinated under non-flooded condition than flooded and the life forms differed. Because the restoration time was short, the similarity between seed bank and vegetation in different restoration successional stages was always <30%. Many wetland species germinated from rhizome fragments, especially C. angustifolia and other wetland species. Our research suggests that the seed bank could retain and restore several wetland species in different restoration successional stages, which can be valuable for vegetation succession and wetland restoration.
An Available Transmission Time Routing Metric for Wireless Ad-Hoc Sensor Networks
Yan-jing Sun,Xue Liu,Bei-bei Zhang
International Journal of Distributed Sensor Networks , 2011, DOI: 10.1155/2011/815987
Abstract: Routing metric is very important for performance of wireless ad hoc sensor networks. ETX and ETT routing metrics cannot accurately estimate the average transmission time since they do not take back-off scheme of IEEE 802.11 in Mac layer into account. We present a new available transmission time (ATT) routing metric based on IEEE 802.11 DCF, which considers available link bandwidth and also takes physical transmission rates into account. A plugin for OLSR routing protocol daemon is implemented on Linux platform, and experiments are taken to compare ATT with ETX and ETT. Our results show that the ATT metric has the lowest packet loss rate and the lowest jitter rate among the analyzed metrics. ATT also outweigh other two metrics in the network performance, so it is the most appropriate for wireless ad hoc sensor networks. 1. Introduction Wireless ad hoc sensor network combines advantages of both wireless LAN and mobile ad hoc networks. It has become the key technology of next generation wireless networks [1]. IEEE 802.11 protocol is widely used as standard. It supports fixed infrastructure and ad hoc operation modes. Wireless nodes working in Ad Hoc mode, can construct routing in multihop collaborative manner. Wireless ad-hoc networks support multihops communication between access points to improve communication coverage and ensure connectivity. Thus, power consumption and mobility is not a major problem, routing protocols generally concern about the link quality [2–4]. Appropriate routing metric is significant for the performance of routing protocols. In [5], expected transmission count (ETX) routing metric is proposed. It considers the impact of links’ packet loss rate on network performance. To further improve the performance of routing protocols, expected transmission time (ETT) is proposed in [6], which is based on the ETX and takes the influence of data transmission rate into consideration. Experiments show that ETT outweighs ETX [7] in network performance. Considering the link-competitive interference of IEEE 802.11 DCF, a new routing metric of expected data rate (EDR) is proposed in [7]. Reference [8] gives a theoretical analysis on various routing metrics and proposes several essential requirements for routing metric design. On the basis of EDR, a new routing metric which comprehensively take interpath and intrapath interference as well as channel diversity is presented and validated by simulation in [9]. In [10], the ETT-routing metric for open link state routing (OLSR) is implemented and tested in wireless test beds. Test results show that ETT
Molecular Evolution of Trehalose-6-Phosphate Synthase (TPS) Gene Family in Populus, Arabidopsis and Rice
Hai-Ling Yang, Yan-Jing Liu, Cai-Ling Wang, Qing-Yin Zeng
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0042438
Abstract: Trehalose-6-phosphate synthase (TPS) plays important roles in trehalose metabolism and signaling. Plant TPS proteins contain both a TPS and a trehalose-6-phosphate phosphatase (TPP) domain, which are coded by a multi-gene family. The plant TPS gene family has been divided into class I and class II. A previous study showed that the Populus, Arabidopsis, and rice genomes have seven class I and 27 class II TPS genes. In this study, we found that all class I TPS genes had 16 introns within the protein-coding region, whereas class II TPS genes had two introns. A significant sequence difference between the two classes of TPS proteins was observed by pairwise sequence comparisons of the 34 TPS proteins. A phylogenetic analysis revealed that at least seven TPS genes were present in the monocot–dicot common ancestor. Segmental duplications contributed significantly to the expansion of this gene family. At least five and three TPS genes were created by segmental duplication events in the Populus and rice genomes, respectively. Both the TPS and TPP domains of 34 TPS genes have evolved under purifying selection, but the selective constraint on the TPP domain was more relaxed than that on the TPS domain. Among 34 TPS genes from Populus, Arabidopsis, and rice, four class I TPS genes (AtTPS1, OsTPS1, PtTPS1, and PtTPS2) were under stronger purifying selection, whereas three Arabidopsis class I TPS genes (AtTPS2, 3, and 4) apparently evolved under relaxed selective constraint. Additionally, a reverse transcription polymerase chain reaction analysis showed the expression divergence of the TPS gene family in Populus, Arabidopsis, and rice under normal growth conditions and in response to stressors. Our findings provide new insights into the mechanisms of gene family expansion and functional evolution.
Fast SAR image segmentation method based on grey fuzzy entropy

MA Miao,LU Yan-jing,

计算机应用研究 , 2009,
Abstract: Aiming at the special character of noise in SAR image, this paper presented a fast SAR image segmentation method based on grey fuzzy entropy, in which not only utilized the gray level information of each pixel, but also involved its spatial correlation information within the eight neighborhood pixels. To decrease the noise-sensibility of the traditional fuzzy entropy methods, it introduced the theory of grey relational analysis to modify the existing fuzzy membership function by selecting the referential sequence and the compared sequences from the original image, and then employed the grey correlation degree of the two kinds of sequences to better the membership function. Consequently, designed a grey fuzzy entropy function to locate the best segmenting threshold. In addition, used PSO, as an swarm intelligent tool, to speed up the segmenting procedure. Some experimental results indicate that the method not only ignores the disturbance of inherent speckle in SAR image, but also provides with some better segmented objects.
Extraction of YC-2 from Sinonovacula constricta and its antioxidant activity
缢蛏YC-2 蛋白的提取及抗氧化作用研究

ZHAO Yan-jing,PEI Bo,HU Hong,WANG Ying,

海洋科学 , 2010,
Abstract: Protein YC-2 was isolated from Sinonovacula constricta by water extraction, ammonia sulphate precipitation (80% saturation), ion exchange chromatography, and gel chromatography, and concentrated by freeze drying. SDS-PAGE and the thiobarbituric acid (TBA) method were used to identify various components and their antioxidant activities in Sinonovacula constricta extracxts. We found that YC-2, a dimeric proteins with a 61 ku large subunit and a 45 ku small subunit, had a high oxidation resistance, the removal rate on ? OH being 99.7 % at 0.627 g/L.
Improved Study Based on DV-Hop Localization Algorithm

WANG Xin-sheng,ZHAO Yan-jing,LI Hai-tao,

计算机科学 , 2011,
Abstract: DV-Hop is a typical rangcfrec localization algorithm for wireless sensor network. Estimably calculating the average hop-distance is one of the most important factors which decide the final localization precision. The average hop-distance estimated only by the nearest anchor node was used in classical DV-Hop localization algorithm, so it brings larger localization error. In order to improve the localization accuracy of the nodes, an improved algorithm based on the original algorithm was proposed. The average hop-distance which is estimated by multiple anchor nodes was considered to use and weighted average hop-distance was introduced instead of the average hop-distance which is used in the classical algorithm. The simulation results indicate that the novel algorithm reduces the localization error caused by the calculation of hop-distance effectively, and improves localization accuracy at the same network environment.
Fast SAR image segmentation method based on grey Tsallis entropy

MA Miao,LU Yan-jing,TIAN Hong-peng,

计算机应用研究 , 2009,
Abstract: Aiming at the speckle noise in SAR image and slow segmentation speed, the paper suggested a fast SAR image segmentation method based on grey theory and Tsallis entropy. In the method, after deduced an approximation image and a gradient image respectively from the origin image via wavelet transform, constructed their approximation-gradient cooccurrence matrix. On the basis of the matrix, designed a 2D grey Tsallis entropy model to locate the best threshold value via grey theory and Tsallis entropy. Additionally, introduced particle swarm optimization (PSO) to speed up the segmentation procedure. Some experimental results indicate that the new algorithm not only shortens the segmenting time obviously, but also ignores the disturbance of inherent speckle in SAR image and illustrates some flexibility in segmenting different objects.
Method of chaotic signals estimation and track based on improved logistic map

HAN Yan-jing,HE Shi-biao,GU Cheng,
,何世彪,谷 诚

计算机应用研究 , 2012,
Abstract: It has been pointed out that chaotic signals could be estimated and tracked by Kalman filter, which solves the problem of chaos synchronization. Unscented Kalman filter UKF technique has a better performance than extended Kalman filter EKF which is based on the first order linearization. But UKF costs too much time on operation in spread spectrum communication system based on improved Logistic chaotic mapping and its algorithm is complex too. It responsed to these shortcomings and also because of the improved Logistic mapping's highest item of Taylor expansion is second-order, this paper proposed so applying the second-order EKF to receiver. It is showed that the receiving system can be accurate to the second order Taylor expansion, which has the same performance as the UKF. Comparing with the UKF, second-order EKF is more simple in algorithm and faster in operation. Simulation results show that second-order EKF is better than UKF in computing speed and complexity, while they have the same BER.
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