Applied Mechanics and Materials Vols. 336-338

Abstract: To acquire a fast method for better volume estimation, a novel soft sensor technique is proposed in this paper. Based on the principle of energy conservation as well as the ideal gas law, mathematical models of charging and discharging process are set up. Afterwards, simulations are carried out to explore the relationship between the estimated volume and the pressure stable time. Finally, experiments with different pneumatic cylinders are conducted to select the suitable estimation mode and also optimize the parameters. Results show that in discharging mode, the average estimation error for volume estimation can be less than 4% with both low pressure and high pressure, making this method quite suitable for industrial application.

Abstract: This paper presents a time-domain CMOS oscillator-based temperature sensor with one-point calibration for test cost reduction. Compared with the former CMOS sensors with linear delay lines, the proposed work composed of a temperature-to-pulse generator with adjustable time gain and a time-to-digital converter (TDC) can achieve lower circuit complexity and smaller area. A temperature-dependent oscillator for temperature sensing was used to generate the period width proportional to absolute temperature (PTAT). With the help of calibration circuit, an adjustable-gain time amplifier was adopted to dynamically adjust the amplified width that was converted by the TDC into the corresponding digital code. After calibration, the fluctuation of the sensor output with process variation can be greatly reduced. The maximum inaccuracy after one-point calibration for six package chips was 1.6 °C within a 0 80 °C temperature range. The proposed sensor fabricated in a 0.35-μm CMOS process occupied a chip area of merely 0.07 mm², achieved a fine resolution of 0.047 °C/LSB, and consumed a low power of 25 μW@10 samples/s.

Abstract: A precise guided system needs an efficient control depending on a precise navigation algorithm, with the ability of getting an accurate initial attitude determination to guarantee the mission success. A navigation system is presented in this paper based on integration between inertial measuring unit and Global Positioning System via Kalman filter approach to satisfy an acceptant accuracy. The two well known Euler and Quaternion attitude determination techniques are implemented to evaluate the body orientation during motion. The carried out system is validated using both simulation data and experimental work. The simulation data is obtained using a six-degree-of-freedom model for a 122mm artillery rocket to obtain all ballistic trajectory parameters during flight. The experimental work is done using a land vehicle taking into consideration the initial attitude determination problem. The results showed high accuracy improvements with high data rates 200 Hz for full state navigation information (position, velocity and attitude).

Abstract: Soil salinization is one form of soil degradation. In this paper, the formation of physical topology known as node deployment in wireless sensor networks is studied based on the characteristics of wireless sensor networks. After calculating the value of the edge length of the grid, the minimum number nodes achieved according to the relationship between the radius of node sensing and radius of node communication. For data transmission, a mobile sink energy efficient routing algorithm based on the shortest path was applied to reduce the energy consumption.

Abstract: The addressing principle of distributed optical fiber Bragg grating (FBG) sensor based on frequency modulation continuous wave (FMCW) multiplexing technology was studied. The effect of grating position information, scanning time and scanning frequency range on the spectrum signals was analyzed by simulation. The FMCW multiplexing system, which was composed of the arbitrary waveform generator, light intensity modulator and multiplier etc, was established and the certifications were delivered by the experimental system.

Abstract: A metalized FBG pressure sensor encapsulated by dual bellows structure was designed based on the strain characteristics of optical fiber Bragg grating (FBG) and osmotic sensing principle. And the experimental system of dual bellows FBG pressure sensor is established. The experimental results show that the pressure sensitivity coefficient of dual bellows FBG pressure sensor is 184.98nm/MPa with the measuring range 10 kPa. The correlation coefficient is better than 99.9% and the resolution is up to 0.05% full scale (FS). The sensitivity of dual bellows structure is high, which indicate that the dual bellows structure encapsulation is suitable for the sensoring in small measuring range.

Abstract: This paper presents a low-power wireless sensor system scheme for monitoring aviation fuel leakage of depots. Based on MSP430 microcontroller and powered by a combination of lithium battery and solar energy, the system employs the photoionization detection (PID) technology to detect the oil leakage and wirelessly reports the detection results by CC2520 radio-frequency communication module. With a low-voltage PID integrated sensor and a specialized active gas-collecting device, the system can effectively measure the concentration of leakage in low power mode. Furthermore, an integrated temperature sensor is used to compensate environmental temperature influence on the PID sensor. The effectiveness analysis and power estimation of the system show that the proposed scheme is suitable for detecting aviation fuel leakage of depots.

Abstract: In recent years, Wireless Sensor Networks (WSNs) have been promising approaches for a variety of application monitoring and capturing the required data from the environment. Due to the restricted communication range and high density of sensor nodes, routing in WSNs has been considered an important field of research over the past decade. The most popular protocol for clustering in WSNs is Low Energy Adaptive Clustering Hierarchy (LEACH) which is based on adaptive clustering technique. The factors affecting LEACH efficiency include Cluster Head (CH), topology structure and routing algorithm. This paper provides in the past years the taxonomy of various clustering and routing techniques based on LEACH in WSNs. The paper highlights the primary principle of each improved protocol and emphasize on their advantages and disadvantages compared to the LEACH.

Abstract: Aiming at improving the identification and judgment on objectives of unmanned weapon system in the battlefield, this paper puts forward a new efficient method to infuse conflict evidence orienting towards shortcomings existing in the Dempster-Shafter (D-S) evidence theory when fusing conflict evidence. This paper is to improve the D-S Evidence Theory, by firstly conducting research on the influence of a certain operational environment on the sensors precision in the unmanned weapon system, and by secondly establishing sensors weight values based on fixed basic probability assignment by exploiting AHP. The improved approach can enhance the reliability of identification result, which has been proved via simulation experiments, and it improves the performance of target recognition system to a certain extent.

Abstract: Key Management is a fundamental security service in distributed sensor networks. The focus of this paper is to design a lightweight group key management scheme to safeguard the data packet passing on the sensor networks under different types of attacks. We propose an energy efficient level-based hierarchical system and build the secure route from the source node to sink node .We compromise between the energy consumption and the shortest path by utilizing the number of neighbors of a sensor when renewing a cluster head or choosing the next hop in the hierarchical clusters. In addition, our protocol contains group communication policies, group membership require-ments and an algorithm for generating a distributed group key for secure communication.