Investigation of the interstitial oxygen behaviors in vanadium alloy: A first-principles study

Xingming Zhang,Yifan Li,Qiaoling He,Ruilian Li,Lei Deng,Liang Wang,Xunlin Liu,Jianfeng Tang,Huiqiu Deng,Wang-Yu Hu 한국물리학회 2018 Current Applied Physics Vol.18 No.2

This study aims at characterizing the interstitial Oxygen (O) behaviors in the Vanadium (V) Alloy by means of the first-principles calculations. For this, the interations between vacancy (Vac) and O interstitil atom are studied in detail to obtain the binding energies and stable structures of the complexes. It can be seen that monovacancy binding with two O atoms occupied the opposing octahedral stie are particularly stable, and is liable to form VacO2 cluster in the V alloys. According to the mass action analysis, the predicted temperature dependence of the concentration for VacOn complexes are presented. Apart from monovacancy, we also consider the trapping behavior of vacancy cluster on the O atoms. The results also prove that one vacancy can trap two O atoms in the V alloys. Based the diffusion theory, we obtain the diffusion coefficients as a function of temperature with or without the vacancy effect in the V alloys. The predicted O diffusion coefficients in defect-free V alloys from our first-principles calculations are in excellent ageement with the experimental data, meanings that the vacancy-limited mechanism does not play the key role for O diffusion in V alloys. Regarding the interactions between vacancy, solutes and O atom, combining with the diffusion barriers of O affected by vacancy and solute, we infer the formation mechanism of the precipitates in the V alloys.

Energy-efficient Routing in MIMO-based Mobile Ad hoc Networks with Multiplexing and Diversity Gains

( Hu Shen ),( Shaohe Lv ),( Xiaodong Wang ),( Xingming Zhou ) 한국인터넷정보학회 2015 KSII Transactions on Internet and Information Syst Vol.9 No.2

It is critical to design energy-efficient routing protocols for battery-limited mobile ad hoc networks, especially in which the energy-consuming MIMO techniques are employed. However, there are several challenges in such a design: first, it is difficult to characterize the energy consumption of a MIMO-based link; second, without a careful design, the broadcasted RREP packets, which are used in most energy-efficient routing protocols, could flood over the networks, and the destination node cannot decide when to reply the communication request; third, due to node mobility and persistent channel degradation, the selected route paths would break down frequently and hence the protocol overhead is increased further. To address these issues, in this paper, a novel Greedy Energy-Efficient Routing (GEER) protocol is proposed: (a) a generalized energy consumption model for the MIMO-based link, considering the trade-off between multiplexing and diversity gains, is derived to minimize link energy consumption and obtain the optimal transmit model; (b) a simple greedy route discovery algorithm and a novel adaptive reply strategy are adopted to speed up path setup with a reduced establishment overhead; (c) a lightweight route maintenance mechanism is introduced to adaptively rebuild the broken links. Extensive simulation results show that, in comparison with the conventional solutions, the proposed GEER protocol can significantly reduce the energy consumption by up to 68.74%.

Distributed Collision-Resolvable Medium Access Control for Wireless LANs with Interference Cancellation Support

( Hu Shen ),( Shaohe Lv ),( Xiaodong Wang ),( Xingming Zhou ) 한국인터넷정보학회 2014 KSII Transactions on Internet and Information Syst Vol.8 No.8

Medium access control is critical in wireless networks for efficient spectrum utilization. In this paper, we introduce a novel collision resolution method based on the technique of known interference cancellation, and propose a new MAC protocol named as CR-MAC, in which AP tries to decode all the collided data packets by combining partial retransmissions and known interference cancellation. As the collided transmissions are fully utilized, less retransmission is required, especially in a crowded network. The NS-2simulation and MATLAB numerical results show that, under various network settings, CR-MAC performs much better than the IEEE 802.11 DCF in terms of the aggregation throughput and the expected packet delay.

VPIT : An Improved Range-Free Localization Algorithm Using Voronoi Diagrams for Wireless Sensor Networks

Xingming Sun,Yachao Hu,Baowei Wang,Jian Zhang,Tao Li 보안공학연구지원센터 2015 International Journal of Multimedia and Ubiquitous Vol.10 No.8

Localization systems have been identified as key issues in the development and operation of wireless sensor networks. The global positioning system (GPS) solves the problem about localization, but it is not suitable for wireless sensor networks. Due to range-free localization approaches requiring low equipped hardware and easy to implement, it is widely used in WSNs localization system. When the node communication radius increases, the accuracy of area-based localization is reduced. It is important to improve the localization accuracy in this situation. In this paper, to improve the accuracy of the node localization, we propose a new range-free localization using Voronoi diagrams based approximate point-in-triangulation test (APIT) algorithm. We compare our algorithm with APIT. Simulation results show that the VPIT improved the precision of localization by narrowing the node's geometry region.

A Genetic Approach for Joint Link Scheduling and Power Control in SIC-enable Wireless Networks

( Xiaodong Wang ),( Hu Shen ),( Shaohe Lv ),( Xingming Zhou ) 한국인터넷정보학회 2016 KSII Transactions on Internet and Information Syst Vol.10 No.4

Successive interference cancellation (SIC) is an effective means of multi-packet reception to combat interference at the physical layer. We investigate the joint optimization issue of channel access and power control for capacity maximization in SIC-enabled wireless networks. We propose a new interference model to characterize the sequential detection nature of SIC. Afterward, we formulize the joint optimization problem, prove it to be a nondeterministic polynomial-time-hard problem, and propose a novel approximation approach based on the genetic algorithm (GA). Finally, we discuss the design and parameter setting of the GA approach and validate its performance through extensive simulations.

Cooperative Control Feedback: On Backoff Misbehavior of CSMA/CA MAC in Channel-Hopping Cognitive Radio Networks

Quan Liu,Yong Lu,Gang Hu,Shaohe Lv,Xiaodong Wang,Xingming Zhou 한국통신학회 2018 Journal of communications and networks Vol.20 No.6

Due to dynamic channel availability in cognitive radionetworks (CRNs), rendezvous problem is known as the mostchallenging issue in the design of media access control (MAC)protocol, which is a key step for secondary users (SUs) to startcommunication. With the concept of blind rendezvous, numerouschannel-hopping sequence (CHS) based rendezvous schemeshave been proposed to solve this problem in these years. Currently,little attention is paid to the design of a carrier sensing multipleaccess/collision avoidance (CSMA/CA) MAC based on theserendezvous schemes and also the rendezvous de-synchronizationproblem brought by multiple rendezvous networking paradigminto MAC design. To this end, we propose a cooperative channelhoppingbased CSMA/CA MAC (named CoCH-CSMA/CA MAC)which works on the top of existing CHS based rendezvous schemes. Resulting from the rendezvous de-synchronization problem, a newtype of collision, named false collision, is identified. As a SU cannotdiscern the false collision by itself, we design a cooperative controlfeedback scheme which employs correlation-based signal detectionto reduce the coordination overhead of cooperation and helps SUsto avoid backoff misbehavior. Moreover, we analyze the behavior ofour MAC protocol and its advantage. Extensive simulations provethat the cooperative control feedback scheme can effectively alleviatethe impact of rendezvous de-synchronization problem on backoffmisbehavior and improve network performance.

Metagenomics analysis of the eff ects of long-term stand age on benefi cial soil bacterial community structure under Chinese ancient mulberry farming practice

Yu Cui,Li Yong,Mo Rongli,Deng Wen,Zhu Zhixian,Hu Xingming 한국원예학회 2020 Horticulture, Environment, and Biotechnology Vol.61 No.6

The ecological distribution and activities of soil microbes can refl ect the infl uence of environmental factors on microbes andchanges in soil fertility. Understanding the community structure of the soil microbes is of great importance to maintaining soilhealth in ancient mulberry plantation ecosystems. In this study, the population structure of soil microorganisms in diff erentages of mulberry plantations was analyzed using high-throughput sequencing technology. A total of 1616, 1568, 1379 and1477 operational taxonomic units were acquired from samples of 3Y (3-year-old), 35Y (35-year-old), 200Y (200-year-old)and 600Y (600-year-old) soils, respectively. The results exhibited that the highest community diversity was found in 35Ysoil, followed by 200Y soil, and showed that the stand age strongly infl uenced the community structure of soil bacteria. Atotal of 23 phyla were detected in 12 samples, and the genus of bacteria that predominated the diff erent stand ages mainlyincluded; Phenylobacterium , Cohnella , Lactococcus , Sphingomonas , Bacillus , and Microbispora . The relative abundanceof Phenylobacterium accounts for 22.6–53.5% of the total abundance. This study showed that the richness and diversity ofthe soil bacteria decreased as the stand age increased in ancient mulberry plantations.