Contrast enhancement of medical ultrasound imaging with reversal phase-inversion pulse technology

A new ultrasound contrast imaging technique was proposed for eliminating the harmonic components from the emission signal transmitted by the broadband ultrasonic system.Reversal phase-inversion pulse was used for the first time to separate the contrast harmonics from the harmonics in the emission signal to improve the detection of contrast micro-bubbles.Based on the nonlinear acoustic theory of finite-amplitude effects and the associated distortion of the propagating wave,the Bessel-Fubini series model was applied to describe the nonlinear propagation effects of the reversal phase-inversion pulse,and the Church's equation for zero-thickness encapsulation model was used to produce the scattering-pulse of the bubble.For harmonic imaging,the experiment was performed using a 64-element linear array,which was simulated by Field II.The results show that the harmonic components from the emission signal can be completely cancelled,and the harmonics generated by the nonlinear propagation of the wave through the tissue,can be reduced by 15-30 dB.Compared with the short pulse,the reversal phase-inversion pulse can improve the contrast and definition of the harmonic image significantly.

Effect of Rare Earth on Microstructure and Corrosion Resistance of Pulse Reversal Current Electrodeposition Ni-Co Alloy Coatings

The effect of adding RE to plating bath on microstructure and corrosion resistance of Ni-Co alloy coatings prepared by pulse reversal current electrodeposition was studied by means of SEM/EDS, electrochemical analysis and corrosion mass loss etc. The results show that adding proper RE to plating solution can promote the microstructure of coatings compacter, the surface smoother and the crystal finer, and improve the corrosion resistance. The coatings exhibite the highest corrosion resistance when the concentration of RE reaches 0.25 g·L -1. The reason of increasing corrosion resistance by adding RE was also investigated.

FLOW CHARACTERISTICS OF WALLFLOW DIESEL PARTICULATE FILTER SYSTEM WITH REVERSE PULSE AIR REGENERATION

To simulate steady airflows inside of wall-flow diesel particulate filters （DPF） with different reverse blowing pipes collocation, a mathematical model of the flow in a DPF is established by an equivalent continuum approach. The experimental results agree well with the theoretical values calculated from the model. Simulation shows that the velocity and the pressure distribution of the filters in the regenerative process are key factors to the filter＇s regeneration. How to decrease the mal-distribution of the flow in the filter and how to achieve the better regenerative performance at the least cost of air consumption in the regenerative process are the ultimate goals of the study. Calculation and experiments show that the goals can be realized through adjusting the angle of two reverse blowing pipes and their relative location suitably.

Pulse cleaning flow models and numerical computation of candle ceramic filters

Analytical and numerical computed models are developed for reverse pulse cleaning system of candle ceramic filters. A standard turbulent model is demonstrated suitably to the designing computation of reverse pulse cleaning system from the experimental and one dimensional computational result. The computed results can be used to guide the designing of reverse pulse cleaning system, which is optimum Venturi geometry. From the computed results, the general conclusions and the designing methods are obtained.

Reversible storage of multiple light pulses in the EIT atomic medium

In this paper, we first present a full numerical simulation for the trapping and retrieval procedure of eight continuing '1' Guassian pulses (i.e., '11111111') in the electromagnetically induced transparency (BIT) medium. This simulation shows that an BIT medium has the ability to store multiple light pulses in a shape-preserving way. And we also, for the first time, give the formula evaluating the maximum number of pulses that can be stored by an EIT medium at one time. This work reveals a new possible way to the reversible storage of the photonic information.

Characterization and corrosion property of nano-rod-like HA on fluoride coating supported on Mg-Zn-Ca alloy×

The poor corrosion resistance of biodegradable magnesium alloys is the dominant factor that limits theirclinical application. In this study, to deal with this challenge, fluoride coating was prepared on MgeZneCa alloy as the inner coating and then hydroxyapatite (HA) coating as the outer coating was depositedon fluoride coating by pulse reverse current electrodeposition (PRC-HA/MgF2). As a comparative study,the microstructure and corrosion properties of the composite coating with the outer coating fabricatedby traditional constant current electrodeposition (TED-HA/MgF2) were also investigated. Scanningelectron microscopy (SEM) images of the coatings show that the morphology of PRC-HA/MgF2 coating isdense and uniform, and presents nano-rod-like structure. Compared with that of TED-HA/MgF2, thecorrosion current density of Mg alloy coated with PRC-HA/MgF2 coatings decreases from 5.72× 10^-5 A/cm2 to 4.32× 10^-7 A/cm^2, and the corrosion resistance increases by almost two orders of magnitude. Inimmersion tests, samples coated with PRC-HA/MgF2 coating always show the lowest hydrogen evolutionamount, and could induce deposition of the hexagonal structure-apatite on the surface rapidly. Theresults show that the corrosion resistance and the bioactivity of the coatings have been improved byadopting double-pulse current mode in the process of preparing HA on fluoride coating, and the PRC-HA/MgF2 coating is worth of further investigation.