Fangmin Li

The HMM-based Modeling for the Energy Level Prediction in Wireless Sensor Networks

The energy conservation is the intrinsic issue of the wireless sensor network (WSN). The lack of energy of some necessary sensor nodes will affect the accurate data aggregation as well as the effective lifetime of the network. In this paper, the problem of predicting which energy level the WSNs or nodes stay in is addressed. Since the primitive method that exchanges messages through nodes could not directly predict the energy level, the stochastic modeling based on hidden Markov model (HMM) is proposed to solve the problem. The energy is divided into several energy levels, i.e. different energy ranges of sensor nodes. Since the state of energy level is the random variable with the value of different energy levels at some time, which holds the characteristic of the Markov chain, it can be modeled as a left-right HMM. Since the energy level cannot be obtained directly, the energy consumption of sensor nodes at a certain time is used as observation states in HMM. Since HMM can perform training process during the running of the WSN, the method can adjust itself to make the best adaptation to the desirable one. Then the trained HMM model can be applied to the prediction of the energy level of the network or sensor nodes. The implementation and simulation of the proposed approach are given in this paper. The simulation shows that the model can effectively predict the energy level and reflect the tendency of the energy consumption, and be applied to other protocols such as energy-efficient routing protocols and so on.

An Optimal Power-Controlled Topology Control for Wireless Sensor Networks

The efficacy of topology control has been shown to be a vital process to maximize the network lifetime of wireless sensor networks. In this paper, we present a distributed topology algorithm with transmission power adjustment based on optimal number of neighbors to raise the network energy-efficiency and the network throughput by reducing channel competition intensity and simplifying the complexity of initial network topology. In the algorithm, every node can adjust its transmission power level and calculate its optimal transmission power according to the optimal number of neighbors, and a virtual clustering scheme based on optimal transmission power is proposed for network topology control, where the network connectivity is also guaranteed. Analysis and simulation results demonstrate the correctness and effectiveness of our algorithm.

Research of UWB signal propagation attenuation model in coal mine

Now, the study of UWB signals propagation attenuation model concentrates mainly on residential indoor environment. In this paper, the monitor of the personnel and equipments in tunnel of coal mine is regarded as application background, the environment in coal mine is looked as a kind of special indoor environment. On the basis of residential indoor UWB propagation model, the tunnel of coal mine is divided into near-field region and far-field region according to Fresnel theory. The propagation mode of UWB signal is mainly multimode in near-field region and mainly waveguide in far-field region. Considering the additional ullage factors that caused by the factors of tunnel, such as personnel and coal transports and slicers etc at the same time, this paper puts forward the UWB signal propagation attenuation model in coal mine. Aiming at the parameter of symbol BER, comparison and analysis that based on the existing residential indoor propagation attenuation model and the model of this paper is done.

Data Transfer Protocol in Bridge Structural Health Monitor System using Wireless Sensor Network

In this paper, a structure health monitor (SHM) system for the bridge is introduced, of which wireless communication and embedding techniques are deployed. After summing up the wireless communication techniques and time synchronization requirements in practical application, a data transfer protocol based on clock synchronization and reliability in wireless sensor networks is proposed, and then its time synchronization error analysis are discussed. All of the related work contributes to the development of a commercial, cost-effective, and reliable SHM system

The design and implementation of process system based on optical fiber Bragg grating sensing signal

In this paper, an optical fiber Bragg grating (FBG) sensing signal process system is designed using the hardware kernel S3C44B0, a 32-bit microprocessor produced by SumSung, and the operation system uCOS-II. The FBG sensing signal demodulating principle and the crucial problems and their solutions in system design are analyzed in detail. Experimental result is also shown in this paper.

A street lamp clustered-control system based on wireless sensor and actuator networks

In order to resolve the problems of city street lamp control and management, a street lamp clustered-control system based on wireless sensor and network (WSANs) is proposed in this paper. In the system, the related information of vehicles running on the road will be detected by the sensors deploying along the both side of the road, and then the sensing data will be passed to the actuators being equipped on the lamps through multi-hop wireless communication. The actuators gather the information from the sensors and regulate the brightness of the lamp by the distributed and cooperated control algorithm. According the security rulers of driving a vehicle, a certain number of lamps in a security distance before and after the vehicle will be turned on. The street lamp clustered-control system is good at energy saving and validated by the experiment results.

Directed diffusion based on link-stabilizing clustering for wireless sensor networks

Reducing power consumption to extend network lifetime with limited energy resource is one of the most important challenges in wireless sensor networks. In addition, the issue of real-time communication is also very important in some practical applications. A directed diffusion algorithm based on link-stabilizing clustering (DDLSC), which is a delay-energy aware routing protocol for wireless sensor networks is proposed in this paper. DDLSC enable a wide range of tradeoffs between delay and energy consumption. The two major components of DDLSC are: a novel stable clustering scheme that forms a wireless sensor network into two layers and the cluster heads construct a virtual backbone for multi-hop communications, and a directed diffusion routing protocol based on the clustering scheme. It is simple, fast to converge, fully distributed and dynamic, and be scalable to the change in network size, density and topology. The performance of DDLSC remains very good even in largescale sensor networks, and it scales with density. Through analysis and simulation evaluations, we show that DDLSC improves the packet delay and system energy consumption compared to other current data-centric routing protocols.

Embedded Technology and Its Application in Digital Manufacturing

The paper mainly introduce the relationship between embedded technology and digital manufacturing, describes the application of embedded technology in digital manufacturing fields, and provides a typical example-NC system based on ARM and DSP, in which the ARM takes charge of the G code input, compiling and interpretation, the simulation display, the users interface and the network interface etc, while the DSP is mainly in charge of real-time tasks such as interpolation computation and path control. Example shows that embedded technology has perspective application in manufacturing industry and we believe it will bring forward an impressive renovation in digital manufacturing fields.

The Application of Embedded Technology in NC System

The paper analyzes the inherent drawbacks of the traditional NC system based IPC, puts forward and then provides the embedded NC system with the architecture of ARM and DSP, in which the ARM takes charge of the G code input, compiling and interpretation, the simulation display, the user’s interface and the network interface etc, while the DSP is mainly in charge of real-time tasks such as interpolation computation and path control. The paper also introduces the hardware and software design in detail. Experiments show that NC system built on the embedded technology can reduce the system hardware scale, facilitate application development, cut down the costs and promote the system’s reliability and real-time performance.

An efficient backoff algorithm for QoS guaranteeing in wireless networks

Wireless networks are required to guarantee the Quality of Service (QoS), including throughput, fairness, delay, etc. IEEE802.11 MAC protocol employs a typical backoff mechanism, Binary Exponential Backoff (BEB) algorithm, to avoid collisions when multiple users try to access the shared wireless channel. Many works on QoS guaranteeing point out that the BEB algorithm introduces the unfairness and serious delay problem into channel access. To solve the problem above, this paper proposes a novel backoff algorithm, which adopts a retransmission counter to measure the network congestion situation. The proposed algorithm also divides the contention window interval into small intervals, and in different intervals, it leverages different backoff strategies. Performance of this algorithm is compared with BEB and other improved backoff algorithms through simulation. The analysis and simulation results show that the proposed backoff algorithm can provide better QoS guaranteeing in terms of throughput, fairness, and delay.