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Deng Z.,Northwestern Polytechnical University | Huang Y.,Northwestern Polytechnical University | Li X.,Xian Special Equipment Inspection Institute | Zhang T.,Northwestern Polytechnical University
Xibei Gongye Daxue Xuebao/Journal of Northwestern Polytechnical University | Year: 2015

Fatigue driving has become an important factor in traffic accidents; warning through timely monitoring of driver fatigue may reduce the incidence of traffic accidents. Using the image processing and the driver's actual situation, we separate driver's face in the background region, use optimized equal illumination method and optimized mouthmap method respectively to extract characteristic parameters of the eyes and the mouth, firstly establish fatigue classifier to identify driver fatigue based on fuzzy neural network classifier, and then implement the driver fatigue detection system in DSP system. Experimental results and their analysis show preliminarily that the system with strong practicability can meet the requirements of dynamic recognition of general fatigue. © 2015, Northwestern Polytechnical University. All right reserved. Source


Lu Y.,Northwestern Polytechnical University | Lu Y.,Xian Special Equipment Inspection Institute | Li J.-L.,Northwestern Polytechnical University | Yang J.-F.,Xian Jiaotong University | Li P.,Northwestern Polytechnical University
Wuji Cailiao Xuebao/Journal of Inorganic Materials | Year: 2015

The co-continuous β-Si3N4 reinforced Al matrix composites were fabricated through squeeze casting of porous β-Si3N4 preforms with porosity of 53.43% which obtained by pressureless sintering. The influences of heat-treatment temperature on the microstructures and mechanical properties of co-continuous β-Si3N4 reinforced Al matrix composites were investigated. With the heat-treatment temperature increase, the degree of interfacial reaction, dislocation density increase, and vickers hardness increases, while fracture toughness decreases, accompanied by flexural strength increasing until 850℃ and then decreasing. The fracture mode of composites changes gradually from ductile intergranular rupture to brittle intergranular rupture. When being heat-treated at 850℃, the composites obtain the optimum mechanical properties with the reaction layer of about 20-50 nm. ©, 2015, Science Press. All right reserved. Source


Lu Y.,Northwestern Polytechnical University | Lu Y.,Xian Special Equipment Inspection Institute | Li J.L.,Northwestern Polytechnical University | Yang J.F.,Xian Jiaotong University | Li P.,Northwestern Polytechnical University
Materials Science Forum | Year: 2014

A new method for preparing porous AlN ceramics with high porosity had been developed by carbothermal reduction of die-pressed green bodies composed of alumina, carbon, sintering additives and AlN seeds. The influences of sintering additives and sintering temperature on the microstructure and mechanical properties of porous AlN ceramics were investigated. XRD analysis proved that complete formation of AlN phase except for minor of glass phase. SEM analysis showed that the resultant porous AlN ceramics occupied fine microstructure and a uniform pore structure. Porous AlN ceramics with a porosity of 41~66% and a strength of 2.7~ 51.8 MPa were obtained. © (2014) Trans Tech Publications, Switzerland. Source


Lu Y.,Xian Special Equipment Inspection Institute | Yang J.,Xian Jiaotong University | Chen Z.,Xian Special Equipment Inspection Institute | Han J.,Xian Special Equipment Inspection Institute | And 2 more authors.
Materials Science Forum | Year: 2013

Porous TiN ceramics with high porosity and uniform pore structure was prepared following the carbothermal reduction reaction between TiO2 and carbon. Influences of sintering additives and particle size of TiO2 on the microstructure and mechanical properties of porous TiN ceramics were investigated. Microstructure and mechanical properties of porous TiN ceramics were studied by XRD, SEM and three-point bending measurement. XRD analysis proved that the TiN phase has completely formed after reaction. In addition, SEM analysis showed that the resultant porous TiN ceramics were composed of fine grains with uniform pore structure. The addition of La2O3 not only accelerated the densification of porous TiN ceramics, but also decreased the porosity and increased the flexural strength. With a decrease in TiO2 particle size, the linear shrinkage increased and the porosity decreased accordingly. © (2013) Trans Tech Publications, Switzerland. Source


Lu Y.,Northwestern Polytechnical University | Lu Y.,Xian Special Equipment Inspection Institute | Li J.L.,Northwestern Polytechnical University | Yang J.F.,Xian Jiaotong University | And 3 more authors.
Materials Science Forum | Year: 2014

The co-continuous AlN composites with different Al contents were fabricated through the squeeze casting of porous AlN preform with varied porosities obtained by carbothermal reduction. The effects of volume fraction of Al phase and the heat treatment temperature on the mechanical properties of composites were investigated. The change of the mechanical properties of composites with the Al content was in line with the mixed rule. With an increase in the Al content, the fracture toughness increased, the Vickers hardness and the flexural strength decreased. The toughen mechanism of composites included ductile rupture and microcrack toughening. The avoiding of excessive interface reaction between AlN and Al was beneficial to the mechanical properties of composites. With an increase in the heat treatment temperature, the stress and the dislocation due to mismatch in the coefficients of thermal expansion increased, the fracture toughness decreased, the vickers hardness and the flexural strength increased. © (2014) Trans Tech Publications, Switzerland. Source

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