Papers by Keyword: SAW

Abstract: SAW sensing technology has advantages of wireless, passive, small size, low cost, fast response, strong anti-electromagnetic radiation, measurable for moving or rotating objects, tolerable for wet dirty or high temperature and other harsh environments. Comparing with the traditional sensing methods, the test of SAW sensing technology can cover almost all the needs of digital substation internet of things.

Abstract: In order to study the electromagnetic interference on SAW (surface acoustic wave) wireless temperature measurement system of the corona discharge, the paper analyzes the characteristics of the frequency spectrum of corona discharge, models the corona discharge and studies its radiation characteristics by simulation on Matlab. Based on this, the experimental platforms of corona discharge is set up. The result of the experiment confirms that corona discharge causes electromagnetic interference to the system and the influence decreases as the distance between the sensor and discharge sources increase. Then the sensor should be kept a certain distance from the discharge sources.

Abstract: —In view of the inefficiency of coding, the complexity of signal extraction and the strict demands of machining in the existing multiple SAW tags system, an anti-collision technique based on Walsh Code was proposed. First, it encodes the 2PSK using the single antenna transmission structure, then it implements the orthogonal encoding of each tag in a multiple SAW tags system using Walsh coding, and finally the encoding information of each tag is acquired by reading the echo signals from the reader and doing cross-correlation operation with each code block in the orthogonal code-set. The proposed approach incorporates both the coding efficiency and the processing technology, simplifies the complexity of signal extraction, and achieves the goal of anti-collision of multiple SAW tags system. The theoretical analysis and simulation verify the feasibility of this technique.

Abstract: The TPMS can not only save fuel and protect the tire, but also make the driver more safety. Tire safety is attracting the driver's attention, the United States had developed laws to enforce the TPMS installation in the car and the deadline is in 2008. In this paper, the basic structure and the implement method of TPMS are introduced. The active sensors are already used in most of the TPMS applications. The SAW theory and some wireless passive SAW pressure and temperature sensors which suit for the TPMS application are illustrated, because the passive sensor is becoming the focus in the TPMS research field. Passive SAW sensor is the good choice for TPMS, according to its wireless, passive, zero age rate, small size etc. The wireless passive SAW TPMS is one of the most important research direction. In this paper, some kinds of passive SAW sensor are introduced, which are used in TPMS.

Abstract: Speed control is the core problem of cutting machine design, the past has been the experience of adjusting the cutting speed, the lack of theoretical basis, randomness. In view of this, according to the basic requirements of cutting efficiency maximization, deduces the removal rate and feed speed, time equation, solving the cutting efficiency problem exists in the design of machine, and established when the removal rate is constant, relation curves of shear rate and time. Use of the method of cutting machine design, can improve the accuracy and scientific design, has higher application value.

Abstract: In order to get the propagation characteristics of surface acoustic wave (SAW) along the piezoelectric crystals surface, the scheme of achieving the propagation characteristics of SAW device based on finite element analysis with ANSYS was proposed in this paper. In this scheme, the model of SAW device was built by the finite element analysis, and the parameter of the electrode and the substrate material was set. The geometry model of SAW device was meshed, and the continuous entity was divided into finite element model. The actual problems of boundary conditions and load in mechanical and electrical were applied to the model. By means of simulating a SAW device with center frequency at 100 MHz, the comparison and analysis between the simulation results and the theory results were presented. Experiments results confirm that the SAW energy is confined into a zone close to the piezoelectric crystals surface and is 1 to 2 wavelengths thick, and the amplitude and energy of the SAW will decrease rapidly with increasing depth.

Abstract: In this paper, the basic principles of the surface acoustic wave (SAW) formed in the periodically poled piezoelectric ceramic has been elaborated theoretically. The modal and harmonic analyses has been performed by utilizing ANSYS software for the periodically poled piezoelectric composite structure (adjacent piezoelectric polarization direction opposite) which composed by piezoelectric ceramic (PZT-4). The data of simulation result have been processed and obtained the following conclusion: the surface wave can be formed in the periodically poled piezoelectric domain with a relatively large amplitude, the motion track of each particle in the SAW is an ellipse by combined the transverse modal displacement and longitudinal modal displacement of each surface node. These conclusions are same as the theoretical values, the simulation results are very useful for designing SAW device with periodically poled piezoelectric ceramic.

Abstract: The finite element analysis on temperature field and stress field during submerged-arc welding (SAW) was carried out by means of assembly language of FORTRAN on the base of ABAQUS. A finite element model was established to study the effects on weld bead formation by using longitudinal magnetic field of low-frequency and different process parameters loaded with moving heat source. A practical SAW experiment was conducted to verify the results of the numerical simulation. It was shown that a molten pool with a wider weld face and a lower penetration could be obtained by the control of longitudinal magnetic field of low-frequency. In addition, the fusion line after this treatment was smoother than with conventional SAW. The results of practical SAW experiment were consistent with those of the numerical simulation. It was confirmed that the longitudinal magnetic field of low-frequency could contribute in diminishing the dilution rate and improving the performance of surfacing layers.

Abstract: The SAW delay-line sensor can obtain the energy of the RF pulse query signal through the wireless method. The RF pulse echo signal of the SAW delay-line sensor is significant effected by the different query pulse width of the RF pulse query signal, which is directly related to the sensor precision. The size of the IDT and reflectors, the distance between the IDT and reflector, and the distance among the different reflectors can affect the selection of the RF pulse query signal. The selection method of the query pulse width is discussed through the theoretical analysis and experimental analysis according to the SAW delay-line transmission characteristics. The query pulse width can be calculated directly through the design parameters of the SAW sensor.

Abstract: High-frequency surface acoustic waves (SAW) were generated and transmitted along single-crystal lithium niobate (LiNbO3). The standing surface waves (SSAW) formed between two parallel inter-digital transducers (IDTs) on a LiNbO3 substrate, were employed to drive the micro-drop mixer. An SSAW device was designed, micro-machined and tested. When an AC signal with the frequency of 61.4MHz was applied to the IDTs, vortex appeared in the drop consisted of two incompatible liquid (ink and glycerol). The evolution of the vortex was recorded in this work. With the evolution of the vortex, mixing process of two incompatible liquid has been demonstrated. The mixer is of significant relevance for many bio-technological applications and in particular for lab-on-chip. While the experimental liquids were mutually incompatible, the ink could only be divided into smaller drops.