Advanced Materials Research Vols. 834-836

Abstract: Strengthening the study on whiskers influence on the reliability of lead-free soldering can improve welding technology and contribute to the overall development of the electronics industry. This paper provides an overview of the study on lead-free solder technology and development, summaries the materials, processes and other reliability issues and welding reliability problems of lead-free solder, finally gives an overview of the research status of whiskers formation mechanism and reliability.

Abstract: Lithium tantalate (LT) is a kind of excellent pyroelectric materials that can be made into high performance pyroelectric detector. As the detector voltage response and detection rate inversely proportional to the thickness of the infrared sensing element, So the thinning of lithium tantalate crystals becomes a key of success. This design uses CMP method to produce 50 μm thickness of LT wafer, and via charge integration method with computer automatic test system to test the pyroelectric coefficient of crystals with different thickness and surface roughness. The pyroelectric coefficient of crystal achieved 203 μC·m^-2k^-1 proves the favorable pyroelectric properties.

Abstract: The twist effects of the bands during the rotation of rectangular bases are analysed in two-dimensional gyromagnetic photonic crystals with a square lattice. We find that extrema’s position have been dislocated from the high-symmetry line in the whole area of the first Brillouin zone (BZ), resulting in erroneous values for the band gap. These make us to calculate the whole first BZ to obtain the authentic band structure instead of boundary calculation.

Abstract: Measuring the clamp-on pressure of high pressure fuel pipe is a shortcut for obtaining injection parameters and fault diagnosis of the fuel injection pumps [1,. Based on the analysis of the fuel injection process of fuel injection pump, analyzed the differences of practical injection process and geometric injection process, and obtained the theory waveform feature points of diesel engine high pressure pipe fuel injection process. In order to obtain the clamp-on pressure waveform which feature points consistent with the theoretical waveform, designed the hardware filter based on MAX293. Considering the clamp-on pressure signal sometimes must also meet the requirements of no delay, designed frequency domain filter. Two filtering methods have reached the expected results.

Abstract: This paper presents a new method to compensate thermocouple sensor non-linearity based on laguerre orthogonal polynomial basis functions neural network. The mathematical model is established based on laguerre artificial neural network for non-linearity compensation. The principle and training algorithms of laguerre orthogonal polynomial basis functions neural network are introduced. The results show that non-linearity compensation method has the advantages of high precision, good real time and strong robustness, etc. The maximum non-linearity error is 0.17%.

Abstract: Aimed at Marine satellite navigation receiver out-field anti-jamming test problem, interference patterns, interference power, ways of setting up the jammer are discussed in this paper. It proposes constraint conditions, calculation methods and evaluation methods of the test system on the lake. The actual design and test use show that the system can better simulate Marine satellite navigation receiver using conditions, and can complete receiver anti-jamming out-field test.

Abstract: As a typical application of Internet of Things (IoT), the issue of protecting security of WSN will be an important problem effecting the expansion of IoT. Since the nodes of WSN are always arranged in an open environment, they are easy to be captured by adversaries. Traditional detections of capture always judge the attack by comparing the absence time of nodes with a certain threshold. In actual applications of WSN, the uncertainty of radio environment and transmission ability of nodes incurs problem of determination of threshold. According to the quality-quantity uncertainty conversion ability of Cloud Model, it is practical to calculate the absence time of nodes in a certain area, to establish the cloud of wireless environment. The threshold will be determined by cloud of wireless environment. Then, Cloud-based First Stage Detection (CFSD) is proposed to detect the node capture attacks in WSN. Simulation results verify that this approach can improve the accuracy of detection and decrease the false alarm probability.

Abstract: In₂O₃ nanotowers have been fabricated on Au item-shaped parallel electrodes using thermal evaporation of the mixed powders of In₂O₃ and graphite with Au catalysts. The morphology and structure of the prepared nanorods are determined on the basis of field-emission scanning electron microscopy (FESEM) and x-ray diffraction (XRD). The self-assembly grown sensors of In₂O₃ nanotowers have excellent performance in sensor response to hydrogen concentration of 1000 ppm under operated temperature of 300°C.

Abstract: In order to solve problems in adaptive learning of diagnosis knowledge, the fault diagnosis system of computer numerical control (CNC) based on multi-agent system (MAS) is studied and the learning mechanism based on artificial immune network is proposed. The structural model of immune network and the corresponding artificial immune algorithm are also designed. The experiment result indicates that that proposed algorithm has faster learning speed and higher classification accuracy.

Abstract: Electromagnetic tomography (EMT) is a recent imaging technique. Its purpose is to determine the distribution of electrical conductivity and magnetic permeability in a given region of interest. EMT is based on the principle of electromagnetic induction. This distribution is computed from the measurements of the induced voltages at several coils placed around the region which are produced by the application of different excitation patterns . Usually images are obtained through inversion of the projection data. The paper represents a fundamental investigation of the potential of using electromagnetic measurements for industrial tomography application. This paper concentrates on image reconstruction of either electrically conducting material or magnetically permeable materials. Finally a number of potential industrial applications for the EMT technique are discussed.