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Zhao G.-H.,Xidian University | Chen B.-X.,Xidian University | Gao Z.-Z.,National Information Control Laboratory
Xi Tong Gong Cheng Yu Dian Zi Ji Shu/Systems Engineering and Electronics | Year: 2010

Conventional pulse compression use a periodical echo of single receive antenna, which is modulated by a certain carrier-frequency, in other words, single spectrum is exploited. But for MIMO radar, as the multi-carrier-frequency signals are transmitted simultaneously, if the spectrum of the target echo after channel separation can be combined to form the whole band spectrum echo, the corresponding range resolution can improve several times as compared with the conventional method, and it will be more convenient for follow-up detection and tracking. Considering the difference between the frequency modulation band and the interval between the adjacent frequencies, the spectrum joint after channel separation will be overlapped or spaced. The methods of spectrum moving of each echo and the spectrum extrapolation with Root-MUSIC algorithm are proposed, by which high-resolution range profile of the target is obtained. Simulation results verify the validity of these methods. Source

Duan J.,National Information Control Laboratory | He Z.,University of Electronic Science and Technology of China
Journal of Systems Engineering and Electronics | Year: 2010

The proposed Doppler measurement technique shows that the Doppler measurements can be accomplished by a single pulse with multiple frequency components through optical fibre delay lines. Range and velocity ambiguity can be removed, and the velocity resolution can be improved dramatically by using long optical fibre delay lines. Furthermore, the velocity resolution can be modified by adjusting the length of optical fibre delay lines. In addition, the proposed radar can achieve high range resolution by using a single wideband pulse. As a result, the new approach can improve radar performance significantly. Source

Ren C.,National Information Control Laboratory
International Journal of Heat and Mass Transfer | Year: 2011

The capillary-driven flow with conductive, convective and evaporative heat transfer occurs in the capillary wick of a loop heat pipe, so-called the inverted meniscus evaporator. An axisymmetric two-dimensional mathematical model is developed to investigate the effects of heat flux and porous structure parameters on wick's working states and performances. The full effects of the interaction between the flowfield and the liquid-vapor interface are adequately considered in this model, as well as the capillary effect of evaporation and the combined effect of conductive, convective and evaporative heat transfer. Wick's performances are introduced and discussed while parametric effects are discussed in detail. Wick's working states are classified into three operating modes while all operating modes are discussed in detail. Furthermore, the phase-diagrams on the q-k t,l plane and the q-K plane are also obtained and discussed. © 2011 Elsevier Ltd. All rights reserved. Source

Geng Z.,Zhejiang University | Shi Z.,Zhejiang University | Yan X.-L.,Zhejiang University | Luo K.-S.,National Information Control Laboratory | Pan W.-W.,Zhejiang University
Journal of Computer Science and Technology | Year: 2015

Inverse lithography technology (ILT) is one of the promising resolution enhancement techniques (RETs), as the advanced integrated circuits (IC) technology nodes still use the 193 nm light source. Among all the algorithms for ILT, the level-set-based ILT (LSB-ILT) is a feasible choice with good production result in practice. However, existing ILT algorithms optimize masks at nominal process condition without giving sufficient attention to the process variations, and thus the optimized masks show poor performance with focus and dose variations. In this paper, we put forward a new LSB-ILT algorithm for process robustness improvement with fast convergence. In order to account for the process variations in the optimization, we adopt a new form of the cost function by adding the objective function of process variation band (PV band) to the nominal cost. We also adopt the hybrid conjugate gradient (CG) method to reduce the runtime of the algorithm. We perform experiments on ICCAD 2013 benchmarks and the results show that our algorithm outperforms the top two winners of the ICCAD 2013 contest by 6.5%. We also adopt the attenuated phase shift mask (att-PSM) in the experiment with test cases from industry. The results show that our new algorithm has a fast convergence speed and reduces the process manufacturability index (PMI) by 38.77% compared with the LSB-ILT algorithm without the consideration of PV band. © 2015, Springer Science+Business Media New York. Source

Liu C.-J.,Harbin Engineering University | Liu C.-J.,National Information Control Laboratory | Liu F.,National Information Control Laboratory | Zhang S.,Harbin Engineering University
Xi Tong Gong Cheng Yu Dian Zi Ji Shu/Systems Engineering and Electronics | Year: 2010

A novel direction of arrival (DOA) estimation algorithm for wideband sources is proposed. This technique estimates DOAs according to a new covariance matrix which is constructed by summing up the covariance matrices of various frequency bins. The new idea originates from the focusing transformation and its validity is proved theoretically. Afterwards, the optimal reference frequency is discussed in detail. The analysis of computational cost shows that the new algorithm has less computational burden compared with the conventional wideband DOA algorithms. Simulation results show that the new algorithm performs better than others and the criterion of choosing optimal reference frequency is also validated by simulations. Source

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