Contribution of Aboveground Litter Decomposition to Soil Respiration in a Subtropical Coniferous Plantation in Southern China

Yidong Wang,Huimin Wang,Zeqing Ma,Wuefa Wen,Qingkang Li,Yunfen Liu,Wiaomin Sun,Guirui Yu 한국기상학회 2009 Asia-Pacific Journal of Atmospheric Sciences Vol.45 No.2

Soil CO₂ efflux (RS) was monitored in a 23-year-old subtropical coniferous plantation in southern China from January 2004 to December 2006. Field measurements of RS with litterfall (CK) and without litterfall (NL) were conducted to evaluate the contribution of aboveground litter decomposition to RS. The results indicated that annual RS from CK ranged from 11.5 mg (C) m<SUP>-2</SUP>h<SUP>-1</SUP> in 2004 to 186.2 ㎎ (C) m<SUP>-2</SUP>h<SUP>-1</SUP> in 2006. The RS of NL was significantly lower than the RS of CK. RS was mainly determined by soil temperature (TS), but it was also affected by soil moisture. Together, both factors explained > 70%of the observed variations in RS. The temperature sensitivity (Q<SUB>10</SUB>) of RS from NLwas lower than that from CK by considering the soil moisture effect. On average, the annual RS of the coniferous plantation was estimated to be 669 g (C)m<SUP>-2</SUP>yr<SUP>-1</SUP> over the study period. The litterfall greatly enhanced the RS, and the respiration from aboveground litter accounted for about 33% of the total RS, in which the fresh litterfall decomposition accounted for a large proportion. The carbon pool of aboveground litter in this young conifer forest is expected to increase continuously.

Fractal Crushing of Solid Particles

Yidong Wang,Chengjian Shao,Yongfu Xu 대한토목학회 2017 KSCE JOURNAL OF CIVIL ENGINEERING Vol.21 No.3

It does not have widely accepted theory to study particle crushing up to now because of the complex and irregular physical structure of the particles. Fractal theory, which employs statistical concepts in order to explain particle crushing, may provide a solution to this problem. The particle size distributions are introduced to determine the fractal dimension. The relationship among the particle size, the crushing strength, crushing energy and the probability of survival of the particles are established based on the fractal model. The theoretical results are based on the spherical particles and ideal crushing experiments under static load. A total of 500 single slag particle crushing tests are carried out for natural slag particles of 2 to 35 mm in diameter. The agreement between the experimental and the theoretical results of the slag particles seems to be satisfactory. The method introduced in this paper not only apply to slag particles, but also any other fractal particles.

Anonymizing Graphs Against Weight-based Attacks with Community Preservation

Yidong Li,Hong Shen 한국정보과학회 2011 Journal of Computing Science and Engineering Vol.5 No.3

The increasing popularity of graph data, such as social and online communities, has initiated a prolific research area in knowledge discovery and data mining. As more real-world graphs are released publicly, there is growing concern about privacy breaching for the entities involved. An adversary may reveal identities of individuals in a published graph, with the topological structure and/or basic graph properties as background knowledge. Many previous studies addressing such attacks as identity disclosure, however, concentrate on preserving privacy in simple graph data only. In this paper, we consider the identity disclosure problem in weighted graphs. The motivation is that, a weighted graph can introduce much more unique information than its simple version, which makes the disclosure easier. We first formalize a general anonymization model to deal with weight-based attacks. Then two concrete attacks are discussed based on weight properties of a graph, including the sum and the set of adjacent weights for each vertex. We also propose a complete solution for the weight anonymization problem to prevent a graph from both attacks. In addition, we also investigate the impact of the proposed methods on community detection, a very popular application in the graph mining field. Our approaches are efficient and practical, and have been validated by extensive experiments on both synthetic and real-world datasets.

Design and analysis of multistage adaptive lateral deformation tracked robot

Yidong Bai,Lingyu Sun,Minglu Zhang 대한기계학회 2022 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.36 No.1

A multistage adaptive lateral deformation tracked robot is proposed based on module design. The mechanical structures of lateral and tracked deformations are established by analyzing the constraints of space barriers and the elastic potential energy change mechanism of internal storage. The interaction of the operating environment and the mechanism is analyzed during the deformation process, and the internal potential energy change mechanism is optimized using the NSGA-II algorithm. The dynamic model is established in RecurDyn software, and the main modules and their coupling relationships are analyzed. Finally, the robot prototype is fabricated, and the obstacle surmounting performance and deformation mode are verified through experimental tests. For small robots, it has the advantages of large load, long driving distance, strong obstacle surmounting ability, and stable steering on the slope, and for robots with the same size, it can increase or decrease its width, has stronger terrain passability and environmental adaptability, so that it can operate in different scenarios within the same mission.

Fast numerical simulation of sheet metal forming using the program QuickForm

Yidong Bao,Junwei Chen,Zhiguo Wang,Wenliang Chen,Wing Lee 한국소성가공학회 2010 기타자료 Vol.2010 No.6

The fast numerical simulation system QuickForm has been self-developed specially for sheet metal forming with complex geometries. In order to resolve the convergence problem of static implicit method due to the change of contact state, the uncoupling solution method of the non-linear differential equations is used in QucikForm program. The bending effect and drawing effect during forming procedure are treated into two separate processes in QuickForm system, so this uncoupling solution has two basic steps. Firstly an approximate method named pre-stressed membrane element is used to achieve the intermediate configuration of sheet in this incremental step before incremental step iteration. The sheet shape of intermediate configuration depends on the current tooling position. Secondly the nonlinear material flow within this intermediate configuration is carried out, which means the nodes of deformed sheet can only slide on this form. The highly efficient iterative solver can be used to the solution of linear equations since the improved conditioning of the linear equations resulting from the uncoupling solution. Numerical simulation results of complex parts demonstrate the higher efficiency and accuracy of the proposed special purpose program.

Anonymizing Graphs Against Weight-based Attacks with Community Preservation

Li, Yidong,Shen, Hong Korean Institute of Information Scientists and Eng 2011 Journal of Computing Science and Engineering Vol.5 No.3

The increasing popularity of graph data, such as social and online communities, has initiated a prolific research area in knowledge discovery and data mining. As more real-world graphs are released publicly, there is growing concern about privacy breaching for the entities involved. An adversary may reveal identities of individuals in a published graph, with the topological structure and/or basic graph properties as background knowledge. Many previous studies addressing such attacks as identity disclosure, however, concentrate on preserving privacy in simple graph data only. In this paper, we consider the identity disclosure problem in weighted graphs. The motivation is that, a weighted graph can introduce much more unique information than its simple version, which makes the disclosure easier. We first formalize a general anonymization model to deal with weight-based attacks. Then two concrete attacks are discussed based on weight properties of a graph, including the sum and the set of adjacent weights for each vertex. We also propose a complete solution for the weight anonymization problem to prevent a graph from both attacks. In addition, we also investigate the impact of the proposed methods on community detection, a very popular application in the graph mining field. Our approaches are efficient and practical, and have been validated by extensive experiments on both synthetic and real-world datasets.

QuickForm Simulation System of Sheet Metal Forming with Trial-and-error Contact Algorithm

Bao Yidong,Liu Lei,Lu Yu,Chen Wenliang 한국소성가공학회 2011 기타자료 Vol.2011 No.8

The QuickForm numerical simulation system has been self-developed specially for sheet metal forming with complex geometries. In order to resolve the convergence problem of static implicit method due to the change of contact state, the uncoupling solution method of the non-linear differential equations is used in QucikForm system. The bending effect and drawing effect during forming procedure are separated into two independent processes in QuickForm system. During bending effect solution, the contact state between the blank nodes and rigid tools should be determined by accurate contact algorithm. A trial-and-error contact algorithm is used in the bending effect calculation process of QuickForm system. The contact procedure is carried out before the solving of bending effect FEM equations, and the contact conditions are treated as the boundary conditions of FEM equations. Numerical simulation results of complex part demonstrate the higher efficiency and accuracy of this contact algorithm and the proposed special purpose program.

Kinetic Resolution of Allylic Alcohol with Chiral BINOL-Based Alkoxides: A Combination of Experimental and Theoretical Studies

Liu, Yidong,Liu, Song,Li, Dongmei,Zhang, Nan,Peng, Lei,Ao, Jun,Song, Choong Eui,Lan, Yu,Yan, Hailong American Chemical Society 2019 JOURNAL OF THE AMERICAN CHEMICAL SOCIETY - Vol.141 No.2

<P>The development and characterization of enantioselective catalytic kinetic resolution of allylic alcohols through asymmetric isomerization with chiral BINOL derivatives-based alkoxides as bifunctional Brønsted base catalysts were described in the study. A number of chiral BINOL derivatives-based alkoxides were synthesized, and their structure-enantioselectivity correlation study in asymmetric isomerization identified a promising chiral Brønsted base catalyst, which afforded various chiral secondary allylic alcohols (ee up to 99%, <I>S</I> factor up to >200). In the mechanistic study, alkoxide species were identified as active species and the phenol group of BINOL largely affected the high reactivity and enantioselectivity via hydrogen bonding between the chiral Brønsted base catalyst and substrates. The strategy is the first successful synthesis strategy of various chiral secondary allylic alcohols through enantioselective transition-metal-free base-catalyzed isomerization. The applicability of the strategy had been demonstrated by the synthesis of the bioactive natural product (+)-veraguensin.</P> [FIG OMISSION]</BR>

AI-based Simulation of Large Deformations of Geomaterials: A Case Study

Zhao , Yidong,Choo, Jinhyun 대한토목학회 2022 대한토목학회 학술대회 Vol.2022 No.10

An Improved Artificial Fish Swarm Algorithm based on Hybrid Behavior Selection

Zhehuang Huang,Yidong Chen 보안공학연구지원센터 2013 International Journal of Control and Automation Vol.6 No.5