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Model Based Separation of Overlapping Latent Fingerprints
Qijun Zhao,Jain, A. K. IEEE 2012 IEEE transactions on information forensics and sec Vol.7 No.3
<P>Latent fingerprints lifted from crime scenes often contain overlapping prints, which are difficult to separate and match by state-of-the-art fingerprint matchers. A few methods have been proposed to separate overlapping fingerprints to enable fingerprint matchers to successfully match the component fingerprints. These methods are limited by the accuracy of the estimated orientation field, which is not reliable for poor quality overlapping latent fingerprints. In this paper, we improve the robustness of overlapping fingerprints separation, particularly for low quality images. Our algorithm reconstructs the orientation fields of component prints by modeling fingerprint orientation fields. In order to facilitate this, we utilize the orientation cues of component fingerprints, which are manually marked by fingerprint examiners. This additional markup is acceptable in forensics, where the first priority is to improve the latent matching accuracy. The effectiveness of the proposed method has been evaluated not only on simulated overlapping prints, but also on real overlapped latent fingerprint images. Compared with available methods, the proposed algorithm is more effective in separating poor quality overlapping fingerprints and enhancing the matching accuracy of overlapping fingerprints.</P>
Guoqing Zhao,Qijun Zhao,Peng Li,Bo Wang 한국항공우주학회 2021 International Journal of Aeronautical and Space Sc Vol.22 No.3
Numerical simulations are performed to investigate the effects of different RPM (revolutions per minute) and different diameter on aerodynamic performances of tiltrotor in both hovering and cruise flight modes. The CLORNS code based on embedded grid and Reynold averaged Navier–Stokes equations is employed. According to the flight state of the tiltrotor, the corresponding comprehensive performance evaluation criteria and aerodynamic trimming strategy are established. On these bases, the numerical investigations on figure of merit and cruise efficiency of XV-15 tiltrotor with different RPM and diameter are conducted, and the results indicate that a large RPM is good for improving the hovering efficiency of tiltrotor, while in cruise mode, tiltrotor with small diameter (root-cut) and RPM helps to enhance the cruise efficiency.
Zhu Jintuo,Jiang Qijun,Ye Yuxuan,He Xinjian,Shao Jiang,Li Xinyu,Zhao Xijie,Xu Huan,Hu Qi 한국산업안전보건공단 산업안전보건연구원 2023 Safety and health at work Vol.14 No.4
Background: During hot environment work tasks with whole-body enclosed anti-bioaerosol suit, the combined effect of heavy sweating and exhaled hot humid air may cause the N95 medical respirator to saturate with water/sweat (i.e., water-blocking). Methods: 32 young male subjects with different body mass indexes (BMI) in whole-body protection (N95 medical respirator + one-piece protective suit + head covering + protective face screen + gloves + shoe covers) were asked to simulate waste collecting from each isolated room in a seven-story building at 27-28°C, and the weight, inhalation resistance (Rf), and aerosol penetration of the respirator before worn and after water-blocking were analyzed. Results: All subjects reported water-blocking asphyxia of the N95 respirators within 36-67 min of the task. When water-blocking occurred, the Rf and 10-200 nm total aerosol penetration (Pt) of the respirators reached up to 1270-1810 Pa and 17.3-23.3%, respectively, which were 10 and 8 times of that before wearing. The most penetration particle size of the respirators increased from 49-65 nm before worn to 115-154 nm under water-blocking condition, and the corresponding maximum size-dependent aerosol penetration increased from 2.5-3.5% to 20-27%. With the increase of BMI, the water-blocking occurrence time firstly increased then reduced, while the Rf, Pt, and absorbed water all increased significantly. Conclusions: This study reveals respirator water-blocking and its serious negative impacts on respiratory protection. When performing moderate-to-high-load tasks with whole-body protection in a hot environment, it is recommended that respirator be replaced with a new one at least every hour to avoid water-blocking asphyxia.
Aeroacoustic Characteristic Analyses of Coaxial Rotors in Hover and Forward Flight
Bo Wang,Chenkai Cao,Qijun Zhao,Xin Yuan,Zheng Zhu 한국항공우주학회 2021 International Journal of Aeronautical and Space Sc Vol.22 No.6
A numerical method combining computational fluid dynamics (CFD) method and Ffowcs Williams–Hawkings (FW–H) equations is established for predicting acoustic characteristics of the coaxial rigid rotor in hovering and forward flight. The unsteady Reynolds-averaged Navier–Stokes (URANS) solver coupled with the moving-embedded grid technique is established to obtain sound source information in the flowfield with high accuracy. On the basis of the accurate solution for the coaxial rotor flowfield, the blade–vortex interaction (BVI) noise in hovering state and the high-speed impulsive (HSI) noise in high-speed forward flight are estimated by the Farassat 1A formula and the FW–H equation with a penetrable data surface (FW–Hpds), respectively. Then the sound pressure distribution characteristics and sound radiation pattern for the coaxial rotor in a hovering state and in a forward flight are obtained through the comparative analysis of the sound pressure time histories and the distribution of sound pressure levels of the upper rotor, lower rotor, and coaxial rotor. The simulation results indicate that significant unsteady characteristics appear in blade aerodynamic loading due to the Venturi effect, blade–vortex interaction phenomenon, and action of the downwash existing in the coaxial rotor flowfield, causing the loading noise of the coaxial rotor to occupy the dominant position in hovering state; the counter-rotating characteristics of the upper and lower rotors cause a significant phase difference between their respective sound pressure waveforms, and the phase difference is determined by the angle between the observation point and the intersection position of the upper and lower blades; the difference with the single rotor in terms of the severe HSI noise generated in the high-speed forward flight is that the noise radiation intensity of the coaxial rotor along both sides in the forward direction exhibits an approximately symmetrical distribution.
A Novel Approach to Mugshot Based Arbitrary View Face Recognition
Dan Zeng,Shuqin Long,Jing Liu,Qijun Zhao 한국광학회 2016 Current Optics and Photonics Vol.20 No.2
Mugshot face images, routinely collected by police, usually contain both frontal and profile views. Existing automated face recognition methods exploited mugshot databases by enlarging the gallery withsynthetic multi-view face images generated from the mugshot face images. This paper, instead, proposesto match the query arbitrary view face image directly to the enrolled frontal and profile face images. Duringmatching, the 3D face shape model reconstructed from the mugshot face images is used to establishcorresponding semantic parts between query and gallery face images, based on which comparison is done. The final recognition result is obtained by fusing the matching results with frontal and profile face images. Compared with previous methods, the proposed method better utilizes mugshot databases without usingsynthetic face images that may have artifacts. Its effectiveness has been demonstrated on the Color FERETand CMU PIE databases.