Propagation of fire fronts in forests

AbstractA moving boundary value problem is considered to investigate the one-dimensional propagation of fire fronts in forests. The problem is solved by the finite difference method with real physical parameters of forests. The theoretical and experimental results are compared to determine the sensitivity of the model for forecasting and control of forest fires

Finite difference model for tidal flows in the Arabian Gulf

AbstractA two-dimensional hydrodynamical model for tidal flows in the Arabian Gulf is developed. The model uses variable mesh-sizes to handle a more detailed tidal current filed in selected sub-regions. In this study, a three-block model scheme is developed in which the deep areas are covered by a relatively coarse grid and the shallow coastal areas by a finer grid. The third block, which is a super-fine mesh in the area of Dhahran, Bahrain and the West coast of Qatar, is included in the model to predict the more detailed tidal current field in this area. A finite difference model is utilized to solve the partial differential equations considered in the model

Foreign Body Removal by Snare Loop: During Intracranial Stent Procedure

We present a case of successful retrieval of an intracranial stent using a snare wire. A 52-year-old woman presented with left border zone infarction. On cerebral angiography, the C6 segment of the left internal carotid artery (ICA) showed significant stenosis. We attempted stenting of the lesion, although stent dislodgement occurred in the ICA C4 segment. We successfully removed it using a snare loop, and there were no complications during the procedure

Percutaneous Transhepatic Release of an Impacted Lithotripter Basket and Its Fractured Traction Wire Using a Goose-Neck Snare: a Case Report

In a patient with a distal common bile duct stone, a fracture of the traction wire of the basket occurring during the performance of mechanical lithotripsy resulted in the impaction of the lithotripter basket with a stone. The impacted lithotripter basket combined with a fracture of the traction wire is a rare complication of endoscopic stone removal. We were able to pull the impacted basket using an Amplatz goose-neck snare inserted via the percutaneous transhepatic route, which resulted in the freeing of the entrapped stone into the dilated supra-ampullary bile duct. The fractured traction wire and basket could be safely removed by pulling the traction wire from the mouth. The present report is the first to describe the safe and effective use of an Amplatz goose-neck snare for the management of a lithotripter basket impacted with a stone and a fractured traction wire

Safety and Efficacy of the FRED Jr Flow Re-Direction Endoluminal Device for Intracranial Aneurysms: Retrospective Multicenter Experience With Emphasis on Midterm Results

Background and Purpose: Flow diversion is increasingly used as an endovascular treatment for intracranial aneurysms. In this retrospective multicenter study, we analyzed the safety and efficacy of the treatment of intracranial, unruptured, or previously treated but recanalized aneurysms using Flow Re-Direction Endoluminal Device (FRED) Jr with emphasis on midterm results. Materials and Methods: Clinical and radiological records of 150 patients harboring 159 aneurysms treated with FRED Jr at six centers between October 2014 and February 2020 were reviewed and consecutively included. Clinical outcome was measured by using the modified Rankin Scale (mRS). Anatomical results were assessed according to the O’Kelly-Marotta (OKM) scale and the Cekirge-Saatci Classification (CSC) scale. Results: The overall complication rate was 24/159 (16%). Thrombotic-ischemic events occurred in 18/159 treatments (11%). These resulted in long-term neurological sequelae in two patients (1%) with worsening from pre-treatment mRS 0–2 and mRS 4 after treatment. Complete or near-complete occlusion of the treated aneurysm according to the OKM scale was reached in 54% (85/158) at 6-month, in 68% (90/133) at 1-year, and in 83% (77/93) at 2-year follow-up, respectively. The rates of narrowing or occlusion of a vessel branch originating from the treated aneurysm according to the CSC scale were 11% (12/108) at 6-month, 20% (17/87) at 1-year, and 23% (13/57) at 2-year follow-up, respectively, with all cases being asymptomatic. Conclusions: In this retrospective multicenter study, FRED Jr was safe and effective in the midterm occlusion of cerebral aneurysms. Most importantly, it was associated with a high rate of good clinical outcome

Behçet's Disease Combined with Various Types of Fistula

Behçet's disease (BD) is a chronic, relapsing, multisystem disorder, characterized by recurrent oral ulcer, genital ulcers, eye lesion, and skin lesion. The underlying pathology is nonspecificvasculitis of all vessel sizes, and severe vasculitis can result in fistula formation of neighboring tissues due to a necroticprocess. Herein, eleven cases of BD combined with fistula are presented. In the present study, various types of fistula were associated; enterocutaneous fistula in six patients, and rectovaginal fistula in two. The other three patients showed aortoduodenal fistula, urethrovaginal fistula and urethrocutaneous fistula. They were treated with a corrective operation, but the prognoses were poor due to frequent relapses

Off-design performance of concentrated solar heat and coal double-source boiler power generation with thermocline energy storage

Integration of solar thermal energy into a coal-fired power station is a promising technology for many coal-dependent countries. This work investigated the off-design performance of such a dual heat source boiler power generation from a system-level modelling approach. As an example study, heat from a solar power tower (SPT) was integrated into a 660 MW supercritical coal-fired power unit, and two integration schemes were considered. A system level analytical model was established that coupled the transient process of heliostat field with one-tank thermocline thermal energy storage. The off-design performance of such a hybrid system in one typical year was analyzed accordingly. The results revealed the importance of the seasonal variation of direct normal insolation (DNI), thermal energy storage scheme and integration methodology. Both the quality of sunshine and the amount of sun flux could influence the solar power efficiency; while an increase in the storage volume could decrease the discharging efficiency. Under the maximum capacity of DNI, increasing the storage capacity by 1 h could improve the efficiency by 0.5–0.8%. For either integration scheme, the coal consumption could be economized at least 9 × 103 ton per year. The maximum of solar efficiency for Scheme I, where solar energy was used to heat the superheat steam, could reach 20.42%, which also came with a penalty of reduced efficiency of thermal receiver. Under the minimum storage capacity, the solar efficiency for Scheme I was changed from 16.7% to 19.6%, while for Scheme II the change was from 14.7% to 17.3%