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State Recognition Based on Hidden Markov Model
Xu Yanyi,Lv Jinhua 보안공학연구지원센터 2016 International Journal of Multimedia and Ubiquitous Vol.11 No.2
This paper puts towards the improvement of the HMM algorithm, then proposed the HMM state identification model of the electronic equipment. It is verified by examples of the experiment, which results show that the HMM state recognition effect is better, recognition rate can reach 94%.Finally, and the experimental results were analyzed, and found the number of hidden states and have bigger influence on the model of training samples.
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Development of Data Monitoring Based on Virtual Instrument
Yanyi Xu,Yongshun Zhang 보안공학연구지원센터 2016 International Journal of Smart Home Vol.10 No.4
The objective of this work is the design and development of the Data Acquisition based on Virtual Instrument and Storage parts of a data monitoring that will be used for a certain control and guide equipment for electronic equipment. The data captured and stored in a database will be an application that will diagnose failure of control and guide equipment. Data acquisition and data Store were developed using finite-state machine model and Virtual Instrument. This paper focuses in the description of the Data Acquisition. The data monitoring is currently installed and applied on a certain control and guide equipment.
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Unified Model for Performance Analysis of IEEE 802.11 Ad Hoc Networks in Unsaturated Conditions
( Changchun Xu ),( Jingdong Gao ),( Yanyi Xu ),( Jianhua He ) 한국인터넷정보학회 2012 KSII Transactions on Internet and Information Syst Vol.6 No.2
IEEE 802.11 standard has achieved huge success in the past decade and is still under development to provide higher physical data rate and better quality of service (QoS). An important problem for the development and optimization of IEEE 802.11 networks is the modeling of the MAC layer channel access protocol. Although there are already many theoretic analysis for the 802.11 MAC protocol in the literature, most of the models focus on the saturated traffic and assume infinite buffer at the MAC layer. In this paper we develop a unified analytical model for IEEE 802.11 MAC protocol in ad hoc networks. The impacts of channel access parameters, traffic rate and buffer size at the MAC layer are modeled with the assistance of a generalized Markov chain and an M/G/1/K queue model. The performance of throughput, packet delivery delay and dropping probability can be achieved. Extensive simulations show the analytical model is highly accurate. From the analytical model it is shown that for practical buffer configuration (e.g. buffer size larger than one), we can maximize the total throughput and reduce the packet blocking probability (due to limited buffer size) and the average queuing delay to zero by effectively controlling the offered load. The average MAC layer service delay as well as its standard deviation, is also much lower than that in saturated conditions and has an upper bound. It is also observed that the optimal load is very close to the maximum achievable throughput regardless of the number of stations or buffer size. Moreover, the model is scalable for performance analysis of 802.11e in unsaturated conditions and 802.11 ad hoc networks with heterogenous traffic flows.
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Circuit Design for Front-End Electrocardiograph
Lv Jinhua,Xu Yanyi 보안공학연구지원센터 2016 International Journal of Multimedia and Ubiquitous Vol.11 No.5
This paper studies the characteristics of ECG signal. In order to complete ECG signal acquisition, the electrocardiograph front-end circuit includes instrumentation amplifier circuit, high-pass filter circuit, 50 Hz notch circuits, four-pass amplification circuit and low-pass filter circuit. To drive subsequent circuit accurately recorded ECG signal, through the Multisim simulation verifies the feasibility of the circuit, which are verified availability through the experimental test.
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Haiyan Wang,Chen Yu,Wanghui Xu,Yupeng Zhang,Yanyi Ma,Yan Lin 대한금속·재료학회 2021 METALS AND MATERIALS International Vol.27 No.12
An experimental study is performed on the microstructure transformation induced by rapid laser welding in the differentregions of Zr61.4Cu27.8Al4Ni6Y0.8bulk metallic glass (BMG). The laser input energy has a remarkable influence on themicrostructure and microhardness of the Zr-based BMGs. The microstructures in different regions of as-welded joints arediverse. Crystallization happens in heat-affected zone (HAZ) with crystalline dendritic phase of CuZr, which results in thedeterioration of the microhardness to 434.9 ± 17.1 HV in HAZ, much lower than that of parent material as 517 ± 5.0 HV. Meanwhile, the element profiles indicate that intragranular segregation of Cu element occurs during the crystallization process. In the center of molten zone (MZ), the structure is fully amorphous and its hardness is close to that of parent material. In the region transiting from MZ to HAZ, some nano-grains with an average size of 20–50 nm are identified. In addition,several flower-like nanostructured grains of Y2O3phase with a size ranging from 50 to 80 nm are formed in MZ’s matrix. The nanocrystallization is believed to be responsible for the enhancement of the Vickers hardness up to 560.1 ± 8.4 HV inthis region.
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