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In this paper, the Doppler spectrum of backscattered echoes from moving target above time-varying sea surfaces is investigated by utilizing the quasi-stationary algorithm, i.e., approximating the time-domain problem by repeatedly implementing the frequency-domain method. In order to fast and accurately solve the composite scattering problem of time-varying sea surfaces with a Low-flying small target above it, a hybrid algorithm of Kirchhoff approximation (KA) and method method-of-moments (MoM) is utilized in this paper for analyzing the Doppler spectrum signatures. The effect of the speed of flying target on Doppler spectrum signatures of a low-flying small target above time-varying sea surface is investigated in this paper.

This work reveals tht with increasing loading rate the critical event for cleavage fracture can be changed from a crack propagation-controlling model through a mixed controlling model of the propagation and nucleation then to a crack nucleation-controlling model.

In this paper, the mechanical and thermal properties of compressed thin film titanium films with 150nm thickness deposited on an organic glass substrate under mechanical and thermal loads were measured and characterized. In order to simulate the thin films in IT which subjected compound loads and to produce the buckle modes, the external uniaxial compression and thermal loading are subjected to the specimen by the symmetric loading device and the electrical resistance film in this experiment. The temperature of the thin film deposited on substrate was measured using thermoelectric couple. The range of temperature accords with the temperature range of the MEMS. It is found that the size and number of the delamination and buckling of the film are depended upon the pre-fixed mechanical loading. The transient conduction and thermal stability of the film and substrate was studied with finite element method.

The nervous system of Caenorhabditis elegans comprises circumferential and longitudinal axon tracts. Netrin UNC-6 is required for the guidance of circumferential axon migrations and is expressed by ventral neuroglia and neurons in temporally and spatially regulated patterns. Migrating axons mediate the UNC-6 signal through the UNC-5 and UNC-40 receptors. It is thought that UNC-6 is secreted and becomes associated with basement membranes and cell surfaces to form gradients that direct circumferentially migrating axons toward or away from the ventral UNC-6 sources. Little is known about the effects of UNC-6 on longitudinally migrating axons. In unc-6, unc-5, and unc-40 null mutants, some longitudinal nerves are dorsally or ventrally misdirected. Furthermore, the organization of axons are disrupted within nerves. We show that cells ectopically expressing UNC-6 can redirect the migrations of some neighboring longitudinal axons, suggesting that the gradients postulated to direct circumferential migration also help specify the dorsoventral positions of these longitudinal nerves. We also manipulated the temporal and spatial expression pattern of UNC-6 by two different means. First, we removed the PVT midline neuron which expresses UNC-6 for a short time during axon outgrowths. Second, we expressed UNC-6 uniformly in the nervous system throughout development. The results suggest that changing UNC-6 expression patterns modify the distribution of the cue by providing new localized sources. This new guidance information is critical for organizing the axons of longitudinal nerves.