摘要：A 1 x 25 star coupler is designed through calculation and beam propagation method (BPM) simulation. Improvement methods are focused on the design of the tapered waveguides in the device, improving the uniformity of the output light power of the star coupler. Utilizing the conventional Si process technology, the device is fabricated based on silicon-on-insulator (SOI) material. The test result shows that the star coupler has a perfect function of power splitting.

摘要：This work investigates the performance of various forward error correction codes, by which the MIMO-OFDM system is deployed. To ensure fair investigation, the performance of four modulations, namely, binary phase shift keying(BPSK), quadrature phase shift keying(QPSK), quadrature amplitude modulation(QAM)-16 and QAM-64 with four error correction codes(convolutional code(CC), Reed-Solomon code(RSC)+CC, low density parity check(LDPC)+CC, Turbo+CC) is studied under three channel models(additive white Guassian noise(AWGN), Rayleigh, Rician) and three different antenna configurations(2×2, 2×4, 4×4). The bit error rate(BER) and the peak signal to noise ratio(PSNR) are taken as the measures of performance. The binary data and the color image data are transmitted and the graphs are plotted for various modulations with different channels and error correction codes. Analysis on the performance measures confirm that the Turbo + CC code in 4×4 configurations exhibits better performance.

摘要：A novel optimization-based method for designing wavelet filter banks in image fusion is proposed. The filter bank design is formulated as a nonlinear optimization problem. The objective function of the optimization problem consists of both the performance metrics of the image fusion, such as the root mean square error （RMSE）, and those of individual filters. The optimization problem is solved using simulating annealing.

摘要：To maximize the throughput of frequency-selective multicast channel, the minimum-phase Finite Impulse Response (FIR) precoder design is investigated in this paper. This problem can be solved in two steps. Firstly, we focus on designing a nonminimum-phase FIR precoder under the criterion of maximizing the throughput, and develop two efficient algorithms for the FIR precoder design from perspectives of frequency domain and time domain. In the second step, based on the theory of spectral factorization, the nonminimum-phase FIR precoder is transformed into the corresponding minimum-phase FIR precoder by a classic iterative algorithm without affecting the throughput. Numerical results indicate that the achievable rate of the proposed design has remarkable improvement over that of existing schemes, moreover, the group delay introduced by the FIR precoder is minimized.

摘要：Uncertainty model validation has been studied for stable system by several authors. This paper considers uncertainty model validation for unstable systems. Under a similar assumption to study for stable systam, a necessary and suffident condition is obtained for unstable uncertainty models not to be invalidated, which generalizes the results of previous study and show that the uncertainty model validation for unstable systems is again a boundary interpolation problem.

摘要：The four-parameter lag-lead compensator design has received much attention in the last two decades. However, most approaches have been either trial-and-error or only for special cases. This paper presents a non-trial-and-error design method for four-parameter lag-lead compensators. Here, the compensator design problem is formulated into a polynomial function optimization problem and solved by using the recently developed sum-of-squares （SOS） techniques. This result not only provides a useful design method but also shows the power of the SOS techniques.

摘要：With the progress of high-bypass turbofan and the innovation of silencing nacelle in engine noise reduction, airframe noise has now become another important sound source besides the engine noise. Thus, reducing airframe noise makes a great contribution to the overall noise reduction of a civil aircraft. However, reducing airframe noise often leads to aerodynamic performance loss in the meantime. In this case, an approach based on artificial neural network is introduced. An established database serves as a basis and the training sample of a back propagation （BP） artificial neural network, which uses confidence coefficient reasoning method for optimization later on. Then the most satisfactory configuration is selected for validating computations through the trained BP network. On the basis of the artificial neural network approach, an optimization pro- cess of slat cove filler （SCF） for high lift devices （HLD） on the Trap Wing is presented. Aerody- namic performance of both the baseline and optimized configurations is investigated through unsteady detached eddy simulations （DES）, and a hybrid method, which combines unsteady DES method with acoustic analogy theory, is employed to validate the noise reduction effect. The numerical results indicate not merely a significant airframe noise reduction effect but also excellent aerodynamic performance retention simultaneously.

摘要：A novel mapping equivalent approach is proposed in this paper, which can be used for analyzing and realizing a memristor-based dynamical circuit equivalently by a nonlinear dynamical circuit with the same topologies and circuit parameters. A memristor-based chaotic circuit and the corresponding Chua＇s chaotic circuit with two output differentiators are taken as examples to illustrate this approach. Equivalent dynamical analysis and realization of the memristor-based chaotic circuit are performed by using Chua＇s chaotic circuit. The results indicate that the outputs of memristor-based chaotic circuit and the corresponding outputs of Chua＇s chaotic circuit have identical dynamics. The proposed approach verified by numerical simulations and experimental observations is useful in designing and analyzing memristor-based dynamical circuits.

摘要：This paper discusses the developement and investigation of a silica microbubble resonator(MBR) that is optimized to cancel mode dispersion with material dispersion, at a wavelength of approximately 1550 nm and maintain a quality factor of an optical mode as large as 5.4 × 10~7. Benefitting from the near-zero dispersion and high quality factor, a primary optical comb is generated in the MBR using cascaded four-wave mixing processes, which span over 300 nm with several tens of teeth. Furthermore, the frequency comb could be gradually tuned by mechanically stretching the MBR. This tunable Kerr comb has multiple potential applications in precision measurements and sensing applications, such as molecular spectroscopy and ranging.

摘要：We study the dynamic behaviour of two intracellufar calcium oscillators that are coupled through gap junctions both to Ca^2＋ and inositol（1,4,5）-trisphosphate （IP3）. It is found that synchronized anti-phase and in-phase oscillations of cytoplasmic cadcium coexist in parameters space. Especially, synchronized anti-phase oscillations only occur near the onset of a Hopf bifurcation point when the velocity of IP3 synthesis is increased. In addition, two kinds of coupling effects, i.e., the diffusions of Ca^2＋ and IP3 among cells on synchronous behaviour, are considered. We fnd that small coupling of Ca^2＋ and large coupling of IP3 facilitate the emergence of synchronized anti-phase oscillations. However, the result is contrary for the synchronized in-phase case. Our findings may provide a qualitative understanding about the mechanism of synchronous behaviour of intercellular calcium signalling.