Tianhuai Ding

Thin Flexible Pressure Sensor Array Based on Carbon Black/Silicone Rubber Nanocomposite

In this paper, the key technologies for the development of the thin flexible pressure sensor array based on carbon black/silicone rubber nanocomposite are reported. The piezoresistive mechanism of the nanocomposite is explained by analyzing the changes in effective conductive paths. The technical data of the sensor system are given. With the measurement range of 0-1 MPa, the maximum measurement deviation is less than 30 kPa.

Research on stress and electrical resistance of skin-sensing silicone rubber/carbon black nanocomposite during decompressive stress relaxation

The decompressive stress relaxation and decompressive resistance relaxation of skin-sensing silicone rubber/carbon black nanocomposite are investigated. The experimental results show that the instantaneous increment of the resistance increases with the increase of the instantaneous decrement of the pressure at the moment immediately after decompression. The compressive stress increases and the electrical resistance decreases gradually with time when the strain of the sample remains constant after decompression. The experimental data of the stress and electrical resistance during decompressive stress relaxation are fitted. The effects of the instantaneous pressure decrement on the exponentials and coefficients of the fitted function are also studied. By analyzing the changes in the effective conductive path and the polymer chain segments, the experimental phenomena have been explained and described.

Propagation of polarized light through textile material.

In this paper a detailed investigation, based on simulations and experiments of polarized light propagation through textile material, is presented. The fibers in textile material are generally anisotropic with axisymmetric structure. The formalism of anisotropic fiber scattering (AFS) at oblique incidence is first deduced and then, based on this formalism and considered multiscattering, a polarization-dependent Monte Carlo method is employed to simulate the propagation of polarized light in textile material. Taking cotton fiber assemblies as samples, the forward-scattering Mueller matrices are calculated theoretically through the AFS-based simulations and measured experimentally by an improved Mueller matrix polarimeter. Their variations according to sample thickness are discussed primarily. With these matrices polar-decomposed, a further discussion on the optical polarization properties of cotton fiber assemblies (i.e., depolarization Δ, diattenuation D, optical rotation ψ and linear retardance δ) versus the thickness is held. Simultaneously, a meaningful comparison of both the matrices and their polar decomposition, generated from the simulations based on isotropic fiber scattering (IFS), with those simulated based on AFS is made. Results show that the IFS-derived values are strikingly different from those that are AFS-derived due to ignoring the fiber anisotropy. Furthermore, all the AFS-derived results are perfectly consistent with those obtained experimentally, which suggests that the Monte Carlo simulation based on AFS has potential applications for light scattering and propagation in textile material.

Study on Virtual Measurement Technology for Near-Bit Dynamic Forces of Bottom-Hole Assembly

A virtual measurement system for investigating the dynamic behaviors of bottom-hole assembly (BHA) in measurement while drilling is designed and set up. Based on the working principle of system, a straight beam strain gauge sensor device and a virtual instrument-based dynamic force wireless measurement system are developed. The axial force, radial force and torque exerted on rotating simulated drillstring are detected multithreadedly in the laboratory. Then the lateral force is calculated. The dynamic force parameters of BHA composed of simulated drillstrings are measured under different weight on bit loads and deviation angles. The experimental results show that lateral force can facilitate the hole deviation control of BHA due to more sensitivity to weight on bit, deviation angle and BHA combination mode. The proposed measurement technology provides the experimental basis for the theoretical analyses of the hole deviation control mechanism of BHA.

Improved Design of Remote Wireless Transmission Terminal using GPRS/GSM Integrated Network

A GPRS/GSM hybrid communication method is designed to develop a low-power RTU (remote terminal unit) for sensor signal acquisition and data transmission of distributed monitoring systems in industrial fields. The hardware architecture, key technology and transmission protocol of RTU are illustrated. Considering to GPRS network congestions, the reliability design of RTU is analyzed. When GPRS connection fails, the RTU switches to the SMS mode to resume the data transmission such that data integrity is ensured. Besides, the RTU is provided with multiple data sampling interfaces and low power mode. The data transmission experimental results show that the average GPRS transmission delay is 1.126~2.669 s, and the data loss rate decreases to 0 in hybrid communication from 6.94%, in single GPRS mode.