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Chronic total occlusion (CTO) lesions are frequent in patients with peripheral and coronary artery disease, and associated with a higher risk of adverse events, including mortality, decreased quality of life, and increased health-care costs. Percutaneous intervention of CTO lesions has been associated with a lower procedural success rate, and current dedicated CTO devices may be of limited use for the non-CTO expert, and associated with increased intraprocedural complication rates. The SoundBite Crossing System (SoundBite Medical Solutions, Inc) is a newly developed device using shockwaves (short-duration, high-amplitude pressure pulses) to facilitate penetration of the proximal cap and crossing of the occlusion. The current report describes the first use of the SoundBite Crossing System in the recanalization of human ex vivo occluded arteries below the knee during a simulated procedure performed under fluoroscopy. Microcomputed tomography and histologic evaluation of the occluded and recanalized segment are provided to support therapeutic mechanism.

Chronic total occlusion (CTO) lesions are frequent in patients with peripheral and coronary artery disease, and are associated with a higher risk of adverse events, including mortality, decreased quality of life, and increased health-care costs. Percutaneous intervention of CTO lesions has been associated with a lower procedural success rate, and current dedicated CTO devices may be of limited use for non-CTO experts, and associated with increased intraprocedural complication rates. The SoundBite Crossing System (SoundBite Medical Solutions, Inc) is a newly-developed device using shockwaves (short-duration, high-amplitude pressure pulses) delivered to the tip of guidewire to facilitate penetration of the proximal cap and crossing of the occlusion. The current report describes the first-in-man use of the SoundBite Crossing System in the recanalization of two occluded lower-limb arteries.

High-g field combustion, such as in rotary ramjet engines, is a promising approach to reduce nitride oxides and combustor size by taking advantage of the flame acceleration due to the buoyancy of the products over the reactants. This paper presents a high-g field combustor design for a rim–rotor rotary ramjet engine. In this device, a premixed flow of air and fuel is ignited in the nonrotating inlet track and then swallowed and stabilized in the rotating combustion chamber. Outboard ignition frees the rotating structure from igniters, increasing the maximal tangential speed of the engine and thus its maximal efficiency. The rotating combustor design benefits from extreme centrifugal fields (105g to 107g) for both stabilizing the flame during ignition and maximize flame velocity. A simple buoyancy-driven combustion model allows estimating the combustor length and shows good agreement with numerical simulations, which demonstrate a combustion efficiency to be higher than 85%, even with some reactants bypass...

Producing closed-cell foams is generally cheaper and simpler than open-cell foams. However, the acoustic and filtration efficiency of closed-cell foam materials is generally poor because it is very difficult for fluid or acoustic waves to penetrate into the material. A new method using shock waves to remove the membranes closing the cell pores (known as reticulation) and thus to improve the acoustic and filtration behavior of closed-cell foam material is presented. Various shock treatments have been carried out on polyurethane and polyimide foams and the following conclusions were drawn: (1) reticulation efficiency increased and thus the airflow resistivity and tortuosity decreased when increasing the amplitude of the shock treatment; (2) the rigidity of the foam is decreased; (3) the process is reliable and repeatable and (4) obtained acoustic performance is comparable to classical thermal reticulation.

International audience; This paper presents the design and experimental results of a new micro gas turbine architecture exploiting counterflow within a single supersonic rotor. This new architecture, called the supersonic rim-rotor gas turbine (SRGT), uses a single rotating assembly incorporating a central hub, a supersonic turbine rotor, a supersonic compressor rotor, and a rim-rotor. This SRGT architecture can potentially increase engine power density while significantly reducing manufacturing costs. The paper presents the preliminary design of a 5 kW SRGT prototype having an external diameter of 72.5mm and rotational speed of 125,000 rpm. The proposed aerodynamic design comprises a single stage supersonic axial compressor, with a normal shock in the stator, and a supersonic impulse turbine. A pressure ratio of 2.75 with a mass flow rate of 130 g/s is predicted using a 1D aerodynamic model in steady state. The proposed combustion chamber uses an annular reverse-flow configuration, using hydrogen as fuel. The analytical design of the combustion chamber is based on a 0D model with three zones (primary, secondary, and dilution), and computational fluid dynamics (CFD) simulations are used to validate the analytical model. The proposed structural design incorporates a unidirectional carbon-fiberreinforced polymer rim-rotor, and titanium alloy is used for the other rotating components. An analytical structural model and numerical validation predict structural integrity of the engine at steady-state operation up to 1000 K for the turbine blades. Experimentation has resulted in the overall engine performance evaluation. Experimentation also demonstrated a stable hydrogen flame in the combustion chamber and structural integrity of the engine for at least 30 s of steady-state operation at 1000 K.

This paper reports on the design, microfabrication, characterization, and testing of the first instrumented micrometer-scale shock tube. This device was fabricated by a series of etching, deposition, and patterning processes of the different structural layers on a silicon substrate to first create an array of direct-sensing piezoelectric pressure sensors followed by the bonding of another substrate to create a microchannel. The resulting assembly is a rectangular channel with a hydraulic diameter of 34 μm and a length of 2000 μm, instrumented with five wall pressure sensors along its length. This device is used to characterize, for the first time, the propagation of shock waves at microscales, where transport effects such as wall friction and heat transfer are important. The results show shock-wave attenuation along the length of the microchannel in accordance with simple analytical models for these flows.

We present the results of a theoretical and experimental study into the influence of various putter head design features on the rotational dynamics of the ball following putter impact. It is found that ball launch conditions can be tailored by designing the putter head with the appropriate combinations of face loft, center of gravity and moment of inertia. Face treatments, such as inserts and grooves, effect the coefficient of restitution and friction coefficient at the contact point and thus provide additional design parameters to control the launch conditions of a putt. Experiments demonstrate that inserts and grooves can modulate the coefficient of restitution of the impact, but not in a manner that gets the ball rolling earlier for fixed length putts.

▪ Abstract The Richtmyer-Meshkov instability arises when a shock wave interacts with an interface separating two different fluids. It combines compressible phenomena, such as shock interaction and refraction, with hydrodynamic instability, including nonlinear growth and subsequent transition to turbulence, across a wide range of Mach numbers. This review focuses on the basic physical processes underlying the onset and development of the Richtmyer-Meshkov instability in simple geometries. It examines the principal theoretical results along with their experimental and numerical validation. It also discusses the different experimental approaches and techniques and how they can be used to resolve outstanding issues in this field.

The lack of a simple and effective wire for crossing chronic total occlusions (CTO) has led to the development of the SoundBite Crossing System. The SoundBite Crossing System is a recanalization tool, and is designed to assist placement of a conventional guidewire in the intraluminal space beyond

Experiments examining the interaction of shock waves with an interface separating two gases of different densities are reported. Flow visualization by the schlieren method and x-ray densitometry reveals that important secondary effects are introduced by the experimental apparatus, especially at the walls of the shock tube from shock wave/boundary layer interaction below, above, and at the interface itself. These effects can impair the observation of the primary phenomenon under study and can lead to the overall deformation of the interface. In particular, the thickness of the viscous boundary layer at the interface is computed using a familiar shock tube turbulent boundary layer model and the occurrence of bifurcation of reflected waves below and above the interface is successfully predicted based on classical bifurcation arguments. The formation of wall vortical structures at the interface is explained in terms of baroclinic vorticity deposition resulting from the interaction of reflected waves with the ...

The effect of varying the explosive sensitivity for a heterogeneous explosive formed of a packed bed of glass beads impregnated with liquid nitromethane (NM) sensitized with diethylenetriamine (DETA) is investigated. The changes in the dependence of critical charge diameter on bead size is investigated at concentrations of 5%, 10%, and 15% DETA over a range of bead diameters from 66 μm to 2.4 mm. Additional measurements are also performed on the critical diameter of the homogeneous liquid explosive itself. Three regions of behavior are identified for the bead-liquid explosive mixture. For bead sizes above approximately 1.5 mm, the critical diameter increases drastically as the amount of DETA is reduced from 15% to 10% and 5%. For bead sizes below approximately 1 mm, the critical diameter is nearly unchanged at concentrations of 10% and 15%. Between 1 and 1.5 mm, a region where the critical diameter increases sharply is found and detonation failure was observed in charge diameters of up to 60.5 mm. This transition region between the two others is found to be wider at lower DETA concentrations. This supports the previous proposition of two distinct mechanisms of detonation propagation which depend on the bead size: propagation through the pores of the media and propagation through the medium material itself.

Producing closed-cell foams is generally cheaper and simpler than open-cell foams. However, the acoustic efficiency of closed-cell foam materials is poor because it is very difficult for the acoustic waves to penetrate the material. A method to remove the membranes closing the cell pores (known as reticulations) and thus to improve the acoustic behavior of closed-cell foam material is presented. The method is based on the propagation of shock waves inside the foam aggregate where both the shock wave generator and the foam are in air at room conditions. Various shock treatments have been carried out on a Polyurethane foams and the following conclusions were drawn: (1) the reticulation rate increases and thus the airflow resistivity decreases while increasing the amplitude of the shock treatment; (2) the softness of the foam increases; (3) the process is reliable and repeatable and (4) the obtained acoustic performance is comparable to classical thermal reticulation.

This paper reports on the design and microfabrication of novel through silicon vias (TSV) that are compatible with high-temperature processing of piezoelectric structures. The present approach uses metal deposition in cavities etched in the SOI handle layer of the wafer and electrically isolated islands in the device layer. This design avoids the shortcomings of previous TSV designs, which either introduce large topologies on the wafer surface, include metals that cannot sustain high-temperature processing or use poor electrical insulators. TSVs microfabricated using this new approach exhibit good performance, specifically small resistance between the front and backside metal pads, isolation from the ground plane and small capacitance between the vias and the ground. These TSVs are eminently suitable for devices requiring high-temperature processing, such as thin-film piezoelectric sensors and actuators.

The acoustical power output of piezoelectric ultrasonic transducer is limited by the material breakdown voltage or the available driving electrical power. While there are well known ways to passively amplify monofrequency acoustic waves generated by a single transducer, e.g., with an exponential horn, there is no obvious way to similarly pump energy into a structure to produce high-intensity broadband acoustic pulses. It was found that the frequency dependant phase velocity inherent to dispersive waveguides can be advantageously exploited to generate high intensity planar pulse waves using a single transducer. With this amplification concept, gain factors as high as 15 have been measured, which can be exploited to produce shock waves in water with a conventional ultrasonic transducer and low power electronics. The paper will present the theoretical underpinnings of this method, as well as its experimental validation. Some potential biomedical applications of this technology will also be discussed.

The present invention is a noise reducing aspirator which is used to carry away air, water, saliva, dental debris from the mouth of a patient or surgical debris. The present invention comprises an open-ended large solid tubular housing having one end adapted to be connected to a source of suction and the other end adapted to be connected to an aspirator tip which will collect air, water, saliva and dental debris. The housing has a sufficient internal ejecting tubular passageway between the ends to accommodate rapid flow of air, water, saliva and dental debris therethrough. The housing includes chamfered pressure venting tubes of equal diameter circularly distributed around, and connecting to, a main suction tube via slanted pathways. The pressure venting tubes reduce and harmonize the noise level of the aspirator and avoid discomforting suction to the patient's tissue. The ends of the housing are designed to secure an aspirator tip or to a source of suction and are designed for easy removal and replacement. The aerodynamic contouring of the present invention ensures that the meeting points of the air flows are as smooth as possible so that shear layer turbulence is reduced to a minimum; resonating cavities, which could create and amplify sound, are eliminated; circular distribution of the pressure venting tubes flatten the intense directional sound peaks originating from the openings of each tube when sound from each tube collides with sound from the others and scatter; and a large solid housing and material selection dampen the minimal amounts of sound produced.