The mode-locked unstable resonator YAG laser

Experimental results on mode-locked action of a polarization coupled unstable resonator YAG laser are reported. The main features of this oscillator are ～ 20 mJ per pulse, good spatial profile and high focusable energy.     

Patient-specific finite element analysis of popliteal stenting

Nitinol self-expanding stents are used for the endovascular management of peripheral artery diseases of the popliteal artery, which is located behind the knee joint. Unfortunately, the complex kinematics of the artery during the leg flexion leads to severe loading conditions, favouring the mechanical failure of the stent, calling for a specific biomechanical analysis. For this reason, in the present study we reconstruct by medical image analysis the patient-specific popliteal kinematics during leg flexion, which is subsequently exploited to compute the mechanical response of a stent model, virtually implanted in the artery by structural finite element analysis (FEA). The medical image analysis indicates a non-uniform configuration change of the artery during the leg flexion, leading to an increase of the vessel curvature above the knee. The computed mechanical response of the stent reflects the non-uniform configuration change of the artery as after the flexion the average stress is higher in the part of the stent located above the knee. Although the proposed analysis is limited to a case-study, it shows the capability of patient-specific FEA simulations to compute the mechanical response of a stent model subjected to the complex and severe loading conditions of the popliteal artery during leg flexion.     

Efficient all-solid-state tunable source based on a passively Q-switched high-power Nd:YAG laser

Received: 27 May 1997/Revised version: 20 June 1997     

Isogeometric Collocation: Cost Comparison with Galerkin Methods and Extension to Adaptive Hierarchical NURBS Discretizations

Collocation is based on the discretization of the strong form of the underlying partial differential equations, which requires basis functions of sufficient order and smoothness. Consequently, the use of isogeometric analysis (IGA) for collocation suggests itself, since splines can be readily adjusted to any order in polynomial degree and continuity required by the differential operators. In addition, they can be generated for domains of arbitrary geometric and topological complexity, directly linked to and fully supported by CAD technology. The major advantage of isogeometric collocation over Galerkin type IGA is the minimization of the computational effort for numerical quadrature. (© 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)     

A model for the optimization of double-clad fiber laser operation

Received: 27 October 1997/Revised version: 12 January 1998     

Enhancement of high-frequency acoustic cavitation effects by a low-frequency stimulation

The cavitation effects given by a high-frequency pulsed ultrasound field are studied with and without the stimulation of a low-frequency field. Sonoluminescence intensity and subharmonic one-half intensity of the high-frequency field are measured. The stimulation gives a sharp rise of both subharmonic and sonoluminescence intensities.     

Generation of a single picosecond pulse using Raman backscattering

The second harmonic pulse train from a mode-locked NdYAG Self-Filtering Unstable Resonator has been compressed by a factor of 2.3 using Raman backscattering. Single pulses of 7.4 picoseconds at=0.68m and with 70 percent success probability have been obtained.