Impact of inter-particle collision on elbow erosion based on DSMC-CFD method

In this work, computational fluid dynamics (CFD) is used to study elbow erosion due to a gas–solid two-phase flow. In particular, the direct simulation Monte Carlo (DSMC) method is used to study the impact of inter-particle collision on the erosion behavior. The two-way coupled Euler–Lagrange method is used to solve the gas–solid flow, and the DSMC method is used to consider the collision behavior between particles. The effects of key factors, such as the particle concentration distribution and inter-particle collision, on the erosion ratio are evaluated and discussed. The effectiveness of the method is verified from experimental data. The results show that the inter-particle collision significantly influences the particle movement path and erosion ratio. When the inter-particle collision is considered, the maximum erosion position is offset. The erosion model proposed by Oka et al., who used the DSMC method, agrees best with the experimental data, and the average percentage error decreases from 39.2 to 27.4%.

A feasibility study on elbow erosion monitoring using active sensing approach and fractional Fourier transform

Elbow erosion monitoring is of great significance to the safety of pipeline systems and maintenance personnel. This paper proposes a new elbow erosion monitoring method, which combines the PZT (lead zirconate titanate) enabled active sensing with the fractional Fourier transform (FrRT), and takes the fractional-order energy peak of the stress wave signal as the damage index. Three 90°-elbows and three 90°-elbow assemblies were used in the experimental studies. Under different erosion degrees, the mass reduction of the three separate elbows was measured by high-precision electronic scale and the residual thickness of the three elbow assemblies was detected by ultrasonic thickness gauge. Two pieces of PZT patches were respectively used to excite and receive the signals in the active sensing. FrFT was used to distinguish the linear sweep signal components of stress wave signals from the energy of other interference or noise signals, and the fractional-order energy peak was used as the damage index. The results show that there is a one-to-one relationship between mass of erosion loss and damage index. Compared with the traditional time domain signal energy method, the new method has the advantage of eliminating the saturation phenomenon. The proposed method and damage index proposed in this paper will be a promising tool for real-time monitoring of elbow erosion.

The results of Baerveldt glaucoma implant surgery performed with the scleral flap and patch technique

Background: We report the results of Baerveldt glaucoma implant (BGI) surgery performed with the scleral flap and patch technique. Patients and methods: This was a retrospective analysis of 97 consecutive patients (107 eyes) who underwent BGI surgery with the scleral flap and patch, and were followed up for >1 year. We evaluated the patients’ post-operative intraocular pressure (IOP), corneal endothelial cell density, and complications (corneal edema, Hoffmann elbow exposure). Results: The preoperative IOP was 32.9 ± 8.6 mmHg. BGI surgery significantly decreased the IOP to 11.1 ± 3.8, 11.3 ± 3.6, 11.3 ± 4.2, 10.7 ± 3.8, and 11.4 ± 3.2 mmHg at 1, 2, 3, 4, and 5 years post-surgery ( p < 0.001), respectively. The success rates at 1, 2, 3, 4, and 5 years were 96.3%, 94.8%, 94.8%, 88.5%, and 88.5%, respectively. Failure occurred in six eyes. The reasons for failure were as follows: a postoperative IOP ⩾21 mmHg in one patient, and loss of light sensation in five patients. No patients required additional glaucoma surgery. There were no cases of Hoffmann elbow erosion. Corneal edema occurred in five patients. Conclusion: BGI surgery performed with the scleral flap and patch significantly decreased the IOP, and no case of Hoffmann elbow erosion was observed over the 5-year post-operative period.