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Xiaodong Wang,Xingguo Liu1,Boqiang Qin,Zhaojun Gu,Hao Xu,Hao Zhu,Guofeng Cheng,Huang Liu 한국생태학회 2015 Journal of Ecology and Environment Vol.38 No.3
In order to understand the mechanisms of conversion between different algal dominance, an experiment was performed in a greenhouse from 22 June to 10 July 2011. The experiment included a treatment group subjected to three instances of nutrient enrichment and a control with no nutrient enrichment. The initial water was dominated by Ankistrodesmus of Chlorophyta. The average water temperature at 08:30 h and 14:00 h during the experiment was 31.6°C and 34.6°C, respec¬tively. The results showed that the total nitrogen (TN), total phosphorus (TP), dissolved total nitrogen (DTN), dissolved total phosphorus (DTP), and soluble reactive phosphorus (SRP) concentrations in the treatment were significantly higher than in the control (P < 0.05). However, the TN/TP and DTN/DTP in the control was higher than in the treatment (P < 0.05). The dominant algae in the control did not change during the experiment, while the dominant algae in the treat¬ment switched to Planktothrix of Cyanophyta on day 9. The chlorophyll a (Chl-a), wet weight of all algae, wet weight of Cyanophyta, and percentage of Cyanophyta in the control were all significantly lower than in the treatment (P < 0.05). Amounts of zooplankton, especially rotifers, were present at the end of the experimental period. The density of rotifers between the control and treatment was not significantly different (P > 0.05), while the copepod density in the treatment was higher than in the control (P < 0.05). We conclude that green algae dominance quickly switches to cyanobacteria dominance after nutrient enrichment in a greenhouse with elevated temperature
A New Special Biometric Identity Based Signature Scheme
Xiaodong Liu,Quan Miao,Daxing Li 보안공학연구지원센터 2008 International Journal of Security and Its Applicat Vol.2 No.1
We propose a new special identity based signature scheme that make uses of fractal transform and entropy arrangement algorithm to generate the public key string from a biometric measurement of signer. A biometric reading provided by the alleged signer would be enough to verify the signature. The characteristic of this scheme is that When verifier finished the verification on the signature, he can compare the biometric information reconstructed by public key with that provided by signer to ensure the relationship between the public key and signer. So, this makes the verification more convenient and intuitionistic. Finally, we describe two possible attacks on this system and suggest ways to combat it.
A Control Method to Make LQR Robust: A Planes Cluster Approaching Mode
Xiaodong Liu,Yunjie Wu,Yu Zhang,Song Xiao 제어·로봇·시스템학회 2014 International Journal of Control, Automation, and Vol.12 No.2
Linear quadratic regulator (LQR) is an optimal controller being used for linear systems, and it can minimize the comprehensive quadratic performance index (QPI) with respect to convergence error and control consumption. However, LQR lacks the robust property to cope with parameter perturbations and external disturbances. Aiming at the above deficiency of LQR, a robust LQR (RLQR) is proposed for linear systems under the guideline of planes cluster approaching mode (PCAM). In the proposed RLQR, one nonlinear item is introduced into control law, and it cooperates with the other linear item to guarantee the global asymptotic stability in the presence of equivalent disturbances. The conditions of global asymptotic stability are deduced by the method of Lyapunov function. Simulation results present that, the chosen LTI plant using RLQR possesses smaller QPI in the existence of time-varying disturbances, compared with the conventional LQR and sliding mode controller (SMC).
A Queuing based Network I/O Scheduling with QoS Guarantee for Virtual Machine
Xiaodong Liu,Zhengying Wen,Miao Wang 보안공학연구지원센터 2015 International Journal of Future Generation Communi Vol.8 No.6
Since multiple VMs share the same network interface card (NIC). The I/O operation of one virtual machine is affected by others. The quality of service (QoS) of the network is hardly guaranteed. This paper presents a queuing based I/O scheduling for big data processing via the cloud, an efficient scheduling strategy with quality of service (QoS) guarantee. Our proposed scheme uses a queuing system to control the I/O bandwidth and provide QoS guarantee for each application. The proposed techniques are implemented on the xen virtual machine monitor (VMM) and evaluated with micro-benchmarks on Linux operation system.
An Ant Colony based Routing Algorithm for Wireless Sensor Network
Xiaodong Liu,Songyang Li,Miao Wang 보안공학연구지원센터 2016 International Journal of Future Generation Communi Vol.9 No.6
Wireless sensor network (WSN) is a new research area of computer science and technology and has a wide application future,more and more attention. It will be much market in application of military, health, home, environment, etc. In WSN, sensor devices have limited supply of energy. The sensor death due to dissipating battery energy is one of the fundamental design issues in WSNs. Hence, energy efficiency is argued to be the most important requirement for WSN. Aiming at the limitation of energy of wireless sensor network node, this paper presents a routing algorithm which is based on the ant’s capability of finding the best paths between a food source and their nests. The pheromone and the energy of the node and delay of the node were combined to affect the pheromone concentration in optimization.Simulation results show that it can balance energy consumption between nodes and prolong the lifecycle of the whole network.
Research On A Flexible Waveform Power Amplifier Adopting Switch-Linear Hybrid(SLH) Scheme
Xiaodong Liu,Sucheng Liu,Lusheng Ge 전력전자학회 2007 ICPE(ISPE)논문집 Vol.- No.-
A novel power amplifier adopting Switch-Linear Hybrid Scheme (SLH-FWPA) is introduced to accomplish flexible waveforms power amplification in a high bandwidth at high output power rating. The final output stage of SLH-FWPA is derived from linear power amplifier architecture to maintain excellent output quality and well dynamic performance; and meanwhile using tracking power supplies for the linear output stage to acquire total system efficiency above 80% generally. Theoretic analysis for SLH-FWPA is given and experimental results verify the implementation of SLH-FWPA.
Xiaodong Liu,Yunjie Wu,Baiting Liu 제어·로봇·시스템학회 2012 International Journal of Control, Automation, and Vol.10 No.5
Considering sliding mode control (SMC) method using the estimation of upper bound on disturbances in motor servo system, if the upper bound is underestimated, the position tracking precision is poor. Contrarily, the control input is overlarge and even chatters violently. To solve the above problems, an adaptive sliding mode controller (ASMC) is proposed. It utilizes a fuzzy decision maker (FDM), which exports the estimation of upper bound on disturbances according to the information of position tracking error and control input. The computer simulations on a dc motor present that the proposed method guarantees satisfactory position tracking accuracy and the chattering at control input is evidently suppressed. Moreover, the output of FDM is sensitive to the changes of disturbances real-timely and precisely. Subsequently, the proposed scheme possesses strong robust performance against disturbances in motor servo system.
Formal Description of the Virtual Machines System Framework
Xiaodong Liu,Li He,Hating Xu 보안공학연구지원센터 2015 International Journal of Multimedia and Ubiquitous Vol.10 No.3
Virtual resources have the duality of hardware and software, which brings new challenges to virtual resources management and manipulation. There is urgent need for formally describing virtual resources in order to effectively reason about virtual resources allocation, scheduling and management. This paper describes the virtual resources and their dynamic behavior. We first give the formal definition of the resources pool and the virtual machine (VM). Then, we describe the dynamic behavior of VMs. In particular, we present a formal description of how virtual resources are used by VMs. This paper reveals the logical laws of virtual resources and their dynamic behaviors and makes the virtualization theory system more rigorous.
Comparison of image masking methods for pump impeller blade region PIV experiments
Xiaodong Liu,Tingting Yan,Qiang Zhong,Zhuqing Liu,Fujun Wang,Yaojun Li,Wei Yang 대한기계학회 2021 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.35 No.6
Due to the blade reflection effect when applying the PIV technology to the internal flow field measurement of rotating machinery, the blade area requires special treatment. In this paper, zero-value, particle image, random number, and mean-value masking methods are compared and analyzed based on particle images from the PIV challenge and rotating impeller. The peak significance and coordinates deviations are used as the masking effect evaluation criteria. The results indicate that an increase in the interrogation window masking area proportion causes a weakening of the PIV calculation particle cluster displacement peak value. The peak position is shifted, which leads to the wrong velocity vector. The masking area proportion should not be higher than 0.7, 0.5, 0.19, and 0.22 for mean-value, random number, zero-value, and particle image masking methods, respectively. The results show that flow field calculation results near the blade boundary are more accurate for mean-value masking.