The behaviour of syntactic foam is strongly dependent on temperature and strain rate. This research focuses on the behaviour of syntactic foam made of epoxy and glass microballoons in the glassy, transition and rubbery regions. Both epoxy and epoxy foam are investigated separately under tension and shear loadings in order to study the strain rate and temperature effects. The results indicate that the strength and strain to failure data can be collapsed onto master curves depending on temperature reduced strain rate. The highest strain to failure occurs in the transition zone. The presence of glass microballoons reduces the strain to failure over the entire range considered, an effect that is particularly significant under tensile loading. However, as the microballoons increase the elastic modulus significantly in the rubbery zone but reduce it somewhat in the glassy zone, the effect on the strength is more complicated. Different failure mechanisms are identified over the temperature-frequency range considered. As the temperature reduced strain rate is decreased, the failure mechanism changes from microballoon fracture to matrix fracture and debonding between the matrix and microballoons.

A conventional inverse synthetic aperture radar image is a 2-D range-Doppler projection of a target and does not provide 3-D information. Three-dimensional imaging using an interferometric technique cannot separate scatterers that have been projected onto the same range-Doppler unit. Multiple-input-multiple-output (MIMO) radar, however, in addition to having a wide virtual aperture and a high cross-range resolution, could also obtain a target's 3-D image in one snapshot. We discuss in this paper the use of time-domain information to improve MIMO radar's imaging quality. A 3-D image alignment algorithm and a rotation vector estimation method are discussed. Simulation results show that image SNR is improved and cross-range sidelobes are mitigated.

Conventional inverse synthetic aperture radar image is a 2-D range-Doppler projection of a target and does not provide 3-D information. Its formation also requires complex motion compensation when the target is uncooperative and maneuvering. On the other hand, multiple-input and multiple-output (MIMO) radar, in addition to having a wide virtual aperture and high cross-range resolution, could also obtain a target's 3-D image in one snapshot and thus have avoided the complex motion compensation needed. In this paper, we propose a 3-D imaging algorithm using three MIMO configurations. The signal model is derived based on a modified zero correlation zone code. A strong scatterer selection criterion is also proposed for the construction of the target profile.

Multiple-input multiple-output (MIMO) radar transmits multiple-coded signals. In matched filter receiver, coded signals are required to have very good auto- and cross-correlation properties. These conditions are difficult to fulfill simultaneously when the lengths of the codes are short and there are many transmit antennas. In this correspondence, a receive filter matrix is designed using quadratic optimization method. The integrated correlations between the transmitted codes and the receive filter matrix in the area around zero shift are constrained under a prescribed level and the output noise power is minimized. A closed form solution is obtained. This integrated sidelobe level (ISL) method is computationally more efficient compared with the peak sidelobe level (PSL) method.

Large 2-D sparse array provides high angular resolution microwave images but artifacts are also induced by the high sidelobes of the beam pattern, thus, limiting its dynamic range. CLEAN technique has been used in the literature to extract strong scatterers for use in subsequent signal cancelation (artifacts removal). However, the performance of DFT parameters estimation based CLEAN algorithm for the estimation of the signal amplitudes is known to be poor, and this affects the signal cancelation. In this paper, DFT is used only to provide the initial estimates, and the maximum likelihood parameters estimation method with steepest descent implementation is then used to improve the precision of the calculated scatterers positions and amplitudes. Time domain information is also used to reduce the sidelobe levels. As a result, clear, artifact-free images could be obtained. The effects of multiple reflections and rotation speed estimation error are also discussed. The proposed method has been verified using numerical simulations and it has been shown to be effective.

Pseudo random codes are easily constructed and can be used in multiple-input multiple-output (MIMO) radar to provide for signal separation. However it has the drawbacks of high aperiodic cross-correlation and auto-correlation sidelobes. Fortunately, in some applications, codes with low correlations are needed only over a narrow window. In this paper, we introduce the Zero Correlation Zone Codes (ZCZC) which have zero correlations in a narrow zone. In other applications, the targets are stationary, which allows for using a long code sequence. In this case we propose an Extended Zero Correlation Zone Codes (EZCZC) where the zero correlation zone is extended to cover the whole sidelobes area. Design examples are given.