Chen Z.,Hunan Environment Biological Polytechnic |
Yang N.,Hunan Environment Biological Polytechnic |
Yao X.,Hunan Environment Biological Polytechnic |
Tian X.,United Information Technology
Shengtai Xuebao/ Acta Ecologica Sinica | Year: 2012
Aims: We studied the life history and distribution of a Taiwania flousiana Gaussen population in Leigong Mountain, Guizhou Province, China, to explain population growth characteristics, and how biological and environmental factors affect population distribution and dynamics. Methods: T. flousiana, a rare and endangered plant, is distributed in patches on southeastern facing slopes at altitudes of 800-1300m on Leigong Mountain. We sampled trees in 30 plots (30m × 30m), and in each plot, we established 9 subplots (10m × 10m) to measure the shrubs, grasses and regeneration of this species. We recorded the diameter at breast height (DBH) of each tree, and then divided them into 13 size classes: S1, H ≤ 2. 5m (DBH < 5. 0cm); S2, H > 2. 5m (DBH < 5. 0cm); S3, 5. 0cm ≤ DBH < 10. 0cm; S4, 10. 0cm ≤ DBH < 15.0cm; S5, 15. 0cm ≤ DBH < 20. 0cm, and so on. We recorded the location of every T. flousiana individual using coordinates (x,y) within each subplot. We determined the population size and structure, life expectancy and survivorship curve of T. flousiana to analyze population structure and dynamics. Important findings: Because T. flousiana seedlings and big trees were rare, the structure and size classes of the population indicate the T. flousiana population is in decline. This appears to be caused by the species biological characteristics and environmental factors. The survivorship curve of this T. flousiana population generally matches the Deevey II type. There are 2 peaks of mortality in the 6th and 12th size classes caused by intraspecific competition for resources and physiological aging, respectively. The life expectancy of this species decreased monotonically during its life span, although T. flousiana seedlings and big trees were rare and had low survival rates. The species generally has a clumped distribution pattern, but this gradually changes over time from a clumped to a random pattern as trees matures from young to middle-aged to old trees. Populations tend to be clumped in the first five size classes, and are distributed-randomly from the 7th size class to the 13th size class. These different developmental stages were related to the biological and ecological characteristics of the species and to microenvironmental conditions. Meanings: We conclude T. flousiana conservation strategies should focus on seedling establishment and conservation, reducing human disturbance and enhancing genetic diversity between populations.
Tian X.-M.,Hunan University |
Zhang D.-F.,Hunan University |
Xie K.,Hunan University |
Hu C.,Hunan Environment Biological Polytechnic |
And 3 more authors.
Tongxin Xuebao/Journal on Communications | Year: 2012
A new set reconciliation algorithm was presented, which called counting-Bloom-filter based set reconciliation(CBFSR). This method represented sets S A and S B as counting Bloom filters, subtracts S A's counting Bloom filter from S B's counting Bloom filter, the differences denoted CBF(S B)-CBF(S A), then determined S B-S A elements in S B with CBF(S B)-CBF(S A), and finally performed union operation on S B-S A and S A. Simulation resdts show counting-Bloom-filter based set reconciliation combines the advantages of exact set reconciliation and approximate set reconciliation, besides gaining all S B-S A elements with single-round messgage exchanges, it can apply to update-intensive distributed systems because counting Bloom filters support element deletion operation.
Tian X.,Hunan University |
Zhang D.,Hunan University |
Xie K.,Hunan University |
Hu C.,Hunan Environment Biological Polytechnic |
And 2 more authors.
Proceedings of 2011 International Conference on Computer Science and Network Technology, ICCSNT 2011 | Year: 2011
We explore the problem of reconciling two similar sets that were maintained by distributed nodes while minimizing communication cost and reconciliation latency. This problem has a wide variety of applications including gossip protocol, mobile database synchronization, distributed file system and maintenance of routing tables in the face of node failures. Existing solutions to exact reconciliation are based on characteristic polynomial interpolation, but their latency is too long. To reduce the latency of such algorithms, we presented an exact set reconciliation algorithm based on Bloom filters (BFESR). The basic idea of BFESR is to obtain symmetric difference size in advance, thus characteristic polynomial values are wholesale transferred. At first, BFESR estimates symmetric difference size using Bloom filters, and calculates multiple polynomial values according to estimated symmetric difference set, and then interpolates rational polynomials, finally recovers the union of sets through factoring the rational polynomials. Theoretical analyses and experimental results show that, compared with the existing methods for exact set reconciliation, BFESR needs only a single round-trip to get the accurate union of sets in most cases, thus greatly reducing reconciliation latency. © 2011 IEEE.
Yi C.,Wuhan University |
Zhan H.,Hunan University of Technology |
Chen J.,Hunan Environment Biological Polytechnic |
Cheng S.,Wuhan University
Huanjing Kexue Xuebao/Acta Scientiae Circumstantiae | Year: 2011
In order to study the characteristics of aerobic granular sludge in a whisk-sequencing batch reactor, WSBR, the granulation effects of aerobic active sludge in the WSBR were compared with the sludge in a traditional SBR. The results indicated that with the same amount of pollyscrylamide, aerobic active sludge was found on 4th day in the WSBR with reasonable secondary flow field, while it was not found in the SBR until the 10th day. Moreover, the diameters of most aerobic active sludge found in WSBR were within the range of 0.9~1.5 mm, SVI was stabilized about of 50 mL·g -1, the specific gravity of granular sludge was increased by 0.0509, MLVSS/MLSS was increased to 81.32%, SOUR reached 1.387 mg·min -1·g -1 and the percentage of water contained in the sludge reached 93.23%. The compact bacteria structure of aerobic granular sludge found in WSBR was much better than that formed in the SBR, which indicated that with reasonable secondary flow field, good aerobic granular sludge could be rapidly formed by applying polyscrylamide coagulation sedimentation theory.
Yi C.,Hubei University |
Zhan H.-H.,China University of Mining and Technology |
Chen J.-D.,Hunan Environment Biological Polytechnic |
Cheng S.-G.,Hubei University
Zhongguo Kuangye Daxue Xuebao/Journal of China University of Mining and Technology | Year: 2012
In order to make active granules form aerobic granular sludge better and faster, based on the addition of polyacrylamide, we focused on the granulation effects of aerobic granular sludge of the secondary flow, using WSBR and the traditional SBR. The results indicate that aerobic active sludge is formed faster in WSBR than in the SBR. Moreover, the diameters of most aerobic active sludge found in WSBR are within the range of 0.9-1.5 mm, SVI is around a stable value of 50 mL/g, the specific gravity of granular sludge is increased by 0.0509, VSS is increased to 81.32%, SOUR reaches to 1.387 mg/(min·g). However, the diameters of most aerobic active sludge found in SBR are within the range of 1.5-2.0 mm, SVI is around a stable value of 70 mL/g, the specific gravity of granular sludge is only increased by 0.0396, VSS is increased to 72.31%, SOUR reaches to 1.063 mg/(min·g), and the percentage of contained water of sludge in SBR is 2.8% higher than that in traditional WSBR. The WSBR is significantly better than the SBR in the aspects of high concentrations of wastewater treatment and Microbial structure, which indicates that with reasonable secondary flow field, good aerobic granular sludge could be rapidly formed by applying PAM coagulation sedimentation theory and the granulation physical model of secondary flow coagulation is proposed.