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The column-to-beam flexural strength ratio (CBFSR) has been used in many seismic codes to achieve the strong column-weak beam (SCWB) failure mode in reinforced concrete (RC) frames, in which plastic hinges appear earlier in beams than in columns. However, seismic investigations show that the required limit of CBFSR in seismic codes usually cannot achieve the SCWB failure mode under strong earthquakes. This study investigates the failure modes of RC frames with different CBFSRs. Nine typical three-story RC frame models with different CBFSRs are designed in accordance with Chinese seismic codes. The seismic responses and failure modes of the frames are investigated through time-history analyses using 100 ground motion records. The results show that the required limit of the CBFSR that guarantees the SCWB failure mode depends on the beam-column connection type and the seismic intensity, and different types of beam-column connections exhibit different failure modes even though they are designed with the same CBFSR. Recommended CBFSRs are proposed for achieving the designed SCWB failure mode for different types of connections in RC frames under different seismic intensities. These results may provide some reference for further revisions of the SCWB design criterion in Chinese seismic codes.

An adaptive targets detector used in polarimetric high resolution radars is presented based on generalized likelihood ratio test (GLRT) criterion. The detector can ensure CFAR property for range-distributed targets in compound-Gaussian clutter. The simulation shows that the proposed detector achieves in general a better detection performance than its counterparts.

It is usually not convenient to use the functions supplied by Visual DSP++ to operate peripherals interactively during debug when an emulator is used. In this paper we develop a simple framework which offers a configurable graphic user interface (GUI), a component to manipulate digital signal processor (DSP) memory and a virtual register mechanism. This framework can help DSP developer with modifying peripherals' registers using a user-friendly dialog. Though the framework is developed using Python, a DSP developer who may not be familiar with Python can manipulate it easily.

Most methods of angular estimation for unresolved targets are based on Swerling II targets model. These methods rely upon the use of pulse-to-pulse frequency agility. In this paper we consider the case that the fluctuation of targets observed are slow, research how the RCS fluctuation of targets affects monopulse radar system and then we address a method of resolving two unresolved targets based on the statistical feature of monopulse angular estimation for slow fluctuation targets. The result of simulation demonstrates that this method is effective.

Non-coherent radar backscattering from chaff clouds is studied, employing a polarimetric radar cross section. Two orthogonally polarimetric scattering cross sections are derived. Both mathematical analysis and measurements show that the depolarization phenomenon is remarkable in radar echo of chaff clouds.

The noncoherent processing can alleviate the effect of phase imbalances in receiver channels of monopulse radar. In this paper, a novel noncoherent processing scheme, which uses logarithmic amplifiers, is considered and explicit expressions are derived for the indicated angle as a function of various imbalances in the receiver channels. Its performance is then analyzed using shift in null position and deviation in slope of the angle sensitivity curve as criteria. Its performance in some aspect is superior to that of the conventional monopulse processing due to symmetrical channels and wide dynamic range.

A tri-pole filter is proposed as a video integrator for scanning radar. Coefficients optimization of the tri-pole filter is carried out via genetic algorithm (GA) which evaluates the fitness of individual using a new function in time-domain. The tri-pole filter requires only 0.1 dB increase in signal-to-noise ratio to provide the same detection capability as the optimum integrator. Moreover, it has better stability than two-pole filter because the distance between its poles and unit circle is further. The tri-pole filter is analyzed and it is shown that its performance is superior to that of the two-pole filter.

The measurements of the two-closely spaced targets are merged when the target echoes are not resolved in angle or radial velocity. Conventional monopulse radar will only obtain single DOA measurement of the centroid. The paper provides an approach to extract direction-of-arrival (DOA) of the target. This method is simple and effective, though it requires complex measurements of signal and a priori knowledge of the polarization scattering characteristics of interference.

This paper investigates conventional theory of angular glint based on phase gradient method and considers that it only was expressed as phase distortion of radar echoes, independent of radar antenna parameters. The analysis demonstrates that echo's non-uniform illumination to radar antenna leads to target glint, which causes the distortion of antenna directional diagram at the same time. The paper also regards the distortion of antenna directional diagram as the result of some non-distortional directional diagrams' addition after rotation and weighting, which provides a convenient method to calculate glint error of complicated-target accurately. The simulation results present that the glint error using the new model is more appropriate than using conventional one.

A focused minimum variance distortionless (MVDR) beamformer for broadband adaptive beamforming is formulated and contrasted with the conventional beamformer. The proposed beamformer involves a preprocessor that focuses the signal spaces at different frequencies to a common one and an MVDR beamformer as the narrowband beamformer following the pre-processor. The merits that result as a consequence are improved computational efficiency of focusing and adaptivity and high beamforming resolution of MVDR with short observation times.

Angular glint caused by a target of dual point sources is discussed in phase gradient method. Deterministic relation between phase gradient and RCS is deduced. On the basis of that, a RCS based compensation method of angular glint is presented. The validity is verified by simulation. For target of multi-point sources, compensation for angular glint error is similar if it is treated as a target of dual point sources.