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The mixing within a full depth lock-exchange gravity current was investigated experimentally with planar laser-induced fluorescence PLIF. The scalar edge of the gravity current was identified via an edge detection algorithm. A strong mixing region located along this edge was extracted from the flow field and analyzed. A dimensionless background potential energy was defined to characterize the local mixing rate in this region, which showed a two-stage behavior. In the section near the nose, mixing rate oscillates strongly under the influence of the lobe and cleft shifting, while in the upper part, the mixing rate grows gradually under the mechanism of billows rolling up.

Gas–liquid mass transfer is a major issue in engineering processes such as wastewater treatment or biogas production since this phenomenon is directly linked to their design and efficiency. In recent years, much research has been done in this area but some gaps still remain in our knowledge of gas–liquid transfer, in particular concerning molecular diffusivity. The determination of molecular diffusivity is commonly based on empirical correlations, such as the widely used Wilke and Chang¹³ expression, valid under specific conditions and with relatively high uncertainties. In the present work, an innovative and promising technique is proposed to determine diffusion coefficients of gases in liquids. This technique is based on visualizing and quantifying oxygen diffusion across a flat gas–liquid interface, in a Newtonian medium, using planar laser induced fluorescence (PLIF) with inhibition. Particle image velocimetry (PIV) experiments were conducted to confirm the hydrodynamic flow field in the liquid phase. Results included the visualization of oxygen diffusion over time, and the quantification of this visualization. The oxygen diffusivity thus determined is in agreement with values found in the literature.

Changes in the curvature have not been reported in degenerative lumbar scoliosis (DLS) when the correction surgery was performed. The purpose of our study was to clarify the influence of the correction surgery of DLS. Twenty-one patients underwent corrective lumbar reconstruction surgery (1998–2003) only at the neurologically affected levels. The spinal curvature was retrospectively evaluated in these 21 patients with DLS using Cobb's methods. The mean preoperative Cobb's angle was 17.7° while the mean postoperative Cobb's angle was 6.1° (p < 0.0001) at 1 month after the surgery and 9.0° at the final follow-up. The correction rate was 65.2% at 1 month after the surgery and 50.2% at the final follow-up. Cobb's angle increased by 2.9°/43.4 months (mean, 0.80°/year) in these procedure. The surgical goals of DLS are the relief of neurological disorders and the cessation of the deterioration of spinal alignment. Strategies for DLS may include complete decompression, or correction of the spinal alignment in elderly patients with poor bone quality. Decompression and correction in the PLIF procedure only at neurologically affected levels may be one of the surgical procedures to challenge DLS.

This is a follow-up study of the surgical efficacy of posterior lumbar interbody fusion (PLIF) for degenerative spondylolisthesis. Over the past 17 years, the authors have applied 7 alternative forms of reinforcement/augmentation to the basic/simple PLIF in an attempt to minimize the rate of fusion complications such as graft collapse, delayed fusion and nonunion. Each variant of the PLIF, along with the basic PLIF was performed on a significant number of patients, yielding a large population for this study. Clinical, radiological and statistical analyses were performed to determine the success of each variant, the basic PLIF, as well as the efficacy of the PLIF in aggregate for cases of degenerative spondylolisthesis. 166 patients were enrolled in this study. The average post-surgical follow-up occurred at 60 months, with a range of 13–188 months encompassing all subjects. Group A (basic/simple PLIF with autologous iliac bone graft)'s rate of fusion complications was 50%. Group B (autologous graft with internal fixation) rate of fusion complications was 36%. Group C (VSP with intervertebral spacers) rate of fusion complications was 13%. The mean recovery rates increased in a stepwise fashion from Group A to B to C. The mean recovery rates in patients with optimal fusion was significantly higher than in patients with fusion complications. The authors conclude that rigid fixation and graft solidarity are essential for achieving optimal results when performing the PLIF. Optimal fusion was correlated with significantly better clinical results.

This paper presents an experimental investigation of the evolution of induced vortices as a solitary wave propagating past a submerged trench. The trajectories of moving fluid particles and transport of trench contents are also analyzed. Using the planar laser induced fluorescence (PLIF) visualization technique, the captured images of the motion of fluorescent dyed fluid particles indicate that, during the process of wave crest passing a trench, a clockwise vortex near the leading edge of the trench is formed and shown to grow vertically while the downstream-transporting front is expanded with more particles carried away from the trench. The incident wave-height has a strong influence on the displacement of moving fluid particles. The numerically determined maximum transporting distances downstream of the experimentally defined trenches were compared with a close match to the values estimated from the extracted images. The removal percentages of trench particles are heavily affected by the incident wave-height. For a square trench with an opening size of 50% of the water depth outside of the trench, numerically, it is found an α = 0.4 solitary wave can entrain nearly 60% of the particles that are initially settled in the trench.

Combustion test diagnose has always been one of the most important technologies for the development of aerospace engineering. Laser diagnostics techniques developed quickly in the past several years. They are used to measure the parameters of the combustion flow field such as velocity, temperature, components concentration with high space and time resolution and brought no disturbance. Planar Laser-Induced Fluorescence, Coherent Anti-Stokes Raman Scattering, Tunable Diode Laser Absorption Spectroscopy and Raman Scattering were introduced systemically in this paper. After analysis their own advantages and disadvantages, it is believed that Raman Scattering system is more suitable for research activities on aero-engine combustion systems.