The paper investigates the observer-based H ∞ synchronization for coronary artery time-delay system under the state immeasurement and external uncertainty. A Luenberger-like state observer, the observation system, is designed to realize the state reconstruction of the master system. Based on the Lyapunov stability theory and Lyapunov-Krasovskii functional (LKF), the observer-based synchronization control condition is derived for a coronary artery system subjected to the external uncertainty bounded by L 2 norm. By introducing the delay-interval bounds and delay-derivative limits in LKF, the time-delays are handled by the delay-range-dependent strategy. The tighter upper bound of inequality can be obtained to reduce the conservation by employing further improved result of Jensen inequality and reciprocally convex approach. Furthermore, a decoupling technique is utilized to render the separate and simple controller and observer synthesis condition, which can be further solved by applying the cone complementary linearization approach respectively. Numerical simulations are listed to exhibit the effectiveness of the presented methodology.

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In guided munitions, the shaped charge jet (SCJ) warhead is located behind the simulation compartment (including the control cabin, the steering gear cabin, and the guidance cabin). Therefore, the order of penetration of the SCJ is the simulation cabin and the target. To study the penetration performance of the SCJ to the target plate, the numerical simulation method is used to study the penetration performance of the designed warhead for the steel target at different standoffs, and the depth of penetration (DOP) at the best standoff is obtained, that is, the DOP of the steel target is about 128 mm. Additionally, the penetration performance of the SCJ warhead to target is studied by numerical simulation and experimental verification. Numerical simulation and experimental results show that the DOP of the SCJ warhead to the steel target is 50 mm without the simulation cabin, and about 30 mm with the simulation cabin. The results show that the penetration performance of SCJ is greatly weakened under the condition of non-optimal standoff, but the rear shaped charge warhead still has a strong penetration performance after completing the penetration of the simulated cabin.

Silicon carbide fiber reinforced silicon carbide ceramic matrix composite (SiCf/SiC composite) is characterized by a high strength-to-density ratio, high hardness, and high temperature resistance. However, due to the brittleness of the matrix material and the anisotropy of the reinforcing phase, it is a huge challenge for machining of the material. The milling method has advantages of a high material removal rate and applicability to complex surface geometry. However, no published literature on milling of SiCf/SiC composite has been found up to now. In this paper, high-speed milling of SiCf/SiC composites was carried out under dry conditions and cryogenic cooling using liquid nitrogen, respectively. Polycrystalline diamond (PCD) and chemical vapor deposition (CVD) diamond cutting tools were used for the milling work. The cutting performance of the two kinds of tools in high-speed milling of SiCf/SiC composites was studied. Tool failure modes and mechanisms were analyzed. The effects of the cooling approach on tool wear and machined surface quality were also investigated. The experimental results showed that under identical cutting parameters and cooling approaches, the PCD tool yielded better cutting performance in terms of a longer tool life and better surface quality than that of the CVD diamond tool. In dry machining, the failure modes of the CVD diamond tool were a large area of spalling on the rake face, edge chipping and severe tool nose fracture, whereas for the PCD tool, only a small area of spalling around the tool nose took place. Compared to the dry machining, the wear magnitudes of both PCD and CVD diamond tools were decreased in cryogenic machining. Additionally, the surface quality also showed significant improvements. This study indicates that the PCD tool is highly suitable for machining of SiCf/SiC composite, and that the cryogenic method can improve machining efficiency and surface quality.