Evaluation and Optimization of Resource Allocation among Multiple Networks

( Dexiang Meng ),( Dongchen Zhang ),( Shoufeng Wang ),( Xiaoyan Xu ),( Wenwen Yao ) 한국인터넷정보학회 2013 KSII Transactions on Internet and Information Syst Vol.7 No.10

Many telecommunication operators around the world have multiple networks. The networks run by each operator are always of different generations, such as 2G and 3G or even 4G systems. Each system has unique characters and specified requirements for optimal operation. It brings about resource allocation problem among these networks for the operator, because the budget of each operator is limited. However, the evaluation of resource allocation among various networks under each operator is missing for long, not to mention resource allocation optimization. The operators are dying for an algorithm to end their blind resource allocation, and the Resource Allocation Optimization Algorithm for Multi-network Operator (RAOAMO) proposed in this paper is what the operators want. RAOAMO evaluates and optimizes resource allocation in the view of overall cost for each operator. It outputs a resource distribution target and corresponding optimization suggestion. Evaluation results show that RAOAMO helps operator save overall cost in various cases.

Control Strategy Design of Grid-Connected and Stand-Alone Single-Phase Inverter for Distributed Generation

Fenghuang Cai,Dexiang Lu,Qiongbin Lin,Wu Wang 전력전자학회 2016 JOURNAL OF POWER ELECTRONICS Vol.16 No.5

Dual-mode photovoltaic power system should be capable of operating in grid-connected (GC) and stand-alone (SA) modes for distributed generation. Under different working modes, the optimal parameters of inverter output filters vary. Inverters commonly operate in GC mode, and thus, a small capacitance is beneficial to the GC topology for achieving a reasonable compromise. A predictive current control scheme is proposed to control the grid current in GC mode and thereby obtain high-performance power. As filter are not optimal under SA mode, a compound control strategy consisting of predictive current control, instantaneous voltage control, and repetitive control is proposed to achieve low total harmonic distortion and improve the output voltage spectrum. The seamless transfer between GC mode and SA mode is illustrated in detail. Finally, the simulation and experimental results of a 4 ㎸A prototype demonstrate the effectiveness of the proposed control strategy.

Individual Aesthetic Differences Evaluation of Yan’an Urban Forests in the Loess Plateau China

Mingxia Zhang,Dexiang Wang,Zhitao Wang,Xinping Zhang,Ganggang Zhang,Yong Xu 보안공학연구지원센터 2014 International Journal of Multimedia and Ubiquitous Vol.9 No.10

A Composite Index-based Approach for Hierarchical Assessment of Forest Ecosystem Health : An Example of Pinus tabulaeformis

Mingxia Zhang,Dexiang Wang,Zhao Xu,Qiuju Guo 보안공학연구지원센터 2014 International Journal of Multimedia and Ubiquitous Vol.9 No.7

Environmental factors and underlying mechanisms of tree community assemblages of pine-oak mixed forests in the Qinling Mountains, China

Zongzheng Chai,Defang Fan,Dexiang Wang 한국식물학회 2016 Journal of Plant Biology Vol.59 No.4

Understanding the mechanisms of assembly of tree communities is very important for restoring and managing pine-oak mixed forests in the Qinling Mountains, China, but the essential mechanisms remain largely unexplored. The objective of this research was to uncover the underlying mechanisms of species coexistence and to identify the key environmental factors influencing the tree community assemblages in these forests. We investigated tree species and 15 environmental factors of topography, soil properties, and stand development of pine-oak mixed forests at an elevation of 1000-2000 m a.s.l. in the Qinling Mountains. Six classical models for the distribution of species abundance were used to fit the observed distributions; a clustering analysis was conducted to divide the ecological species groups, and a redundancy analysis examined the relationship between species assemblages and various environmental factors. Zipf-Mandelbrot, neutral-theory, log-normal, and Zipf models performed well in fitting the patterns of species-abundance distribution in the pine-oak mixed forests, which was related to the complexity of the community structure of the forests. A special combination of the Zipf-Mandelbrot and neutral-theory models, however, best explained the mechanism of species coexistence for the forests and indicated that these forests were progressive successional communities able to maintain stable development during succession. In addition, multiple factors controlled the tree community assemblage of pine-oak mixed forests in the mountainous regions, although available potassium, slope aspect, average tree DBH, and slope position were significant environmental variables.

Control Strategy Design of Grid-Connected and Stand-Alone Single-Phase Inverter for Distributed Generation

Cai, Fenghuang,Lu, Dexiang,Lin, Qiongbin,Wang, Wu The Korean Institute of Power Electronics 2016 JOURNAL OF POWER ELECTRONICS Vol.16 No.5

Dual-mode photovoltaic power system should be capable of operating in grid-connected (GC) and stand-alone (SA) modes for distributed generation. Under different working modes, the optimal parameters of inverter output filters vary. Inverters commonly operate in GC mode, and thus, a small capacitance is beneficial to the GC topology for achieving a reasonable compromise. A predictive current control scheme is proposed to control the grid current in GC mode and thereby obtain high-performance power. As filter are not optimal under SA mode, a compound control strategy consisting of predictive current control, instantaneous voltage control, and repetitive control is proposed to achieve low total harmonic distortion and improve the output voltage spectrum. The seamless transfer between GC mode and SA mode is illustrated in detail. Finally, the simulation and experimental results of a 4 kVA prototype demonstrate the effectiveness of the proposed control strategy.

Origin of dolomitization in the Lower Cretaceous Bayanhua Group dolomitized rocks, Bayindulan Sag, Erlian Basin

Fugui He,Xianzhi Gao,Xianzheng Zhao,Huilai Wang,Dexiang Yang,Quan Wang 한국지질과학협의회 2017 Geosciences Journal Vol.21 No.4

The Bayindulan Sag situated in Erlian Basin, northeast China, is characterized by pervasive dolomitization in Upper A4 Member to Lower T1 Member of Bayanhua Group. These stratum in the Lower Cretaceous Bayanhua Group were deposited in a lacustrine environments. The main objective of this study is to identify the origin of dolomitization and distribution model of dolomitized rocks. Based on petrographic examination, mud-crystal dolomites (<0.03 mm), silt-crystal dolomites (0.03–0.1 mm) and fine-crystal dolomites (0.1– 0.25 mm) have been observed, and the former two types were predominant. Meanwhile, only one type of dolomite have been defined: replacive dolomite. A variety of dolomite textures have also been observed, the major ones of them are scattered, blocky, joined and annular textures. These dolomites have strongly depleted oxygen isotopic values from –17.48‰ to –6.96‰ with the average of –10.48‰ (PDB), carbon isotopic values from 0.24‰ to 8.37‰ with the average of 5.39‰ (PDB). The obvious depletion of oxygen isotopic was presented as a result of the increase in temperature with progressive burial, and the high carbon isotopic content of dolomites maybe result from the involvement of CO2 in the dolomitization process. These CO2 were generated by bio-methanation which commonly took place in moderately deep burial environments. The Sr values from 62.4 ppm to 262 ppm as well as the Sr/Ba ratios from 0.24 to 0.76 in Tengyi Formation mudstones indicate the freshwater lacustrine sedimentary environments. Taking the petrographic and geochemical data into consideration, the conclusion that the dolomites have formed in a freshwater environments during deep burial depths at temperatures of at least 60 °C can be drawn. Petrographic observations and mineralogy analyses indicate that dolomitization is closely associated with tuffaceous materials, the Mg needed for the dolomitization is provided by dissolution of tuffaceous materials and dolomitization is most probably driven by tuffaceous materials alteration at elevated temperatures.