Effect of the Submerged Vortex Cavitation Occurred in Pump Suction Intake on Hydraulic Forces of Mixed Flow Pump Impeller

The effect of submerged vortices on the hydraulic forces of a mixed flow pump impeller was studied using a model pump with an intake sump. The experiments comprise observation of submerged vortices reaching the impeller with a high-speed video camera and measurement of the velocity distribution around the submerged vortex by PTV (particle tracking velocimetry) to obtain the strength of the vortex. Measurement results are compared with CFD (computational fluid dynamics) calculation to evaluate their accuracy. Hydraulic forces on the model pump when the submerged vortex reached the pump impeller was measured with load cells. The relationship between the strength of the submerged vortex and the effect of the vortex on the fluctuation of the hydraulic forces are describe

Simulation des écoulements diphasiques dans les stations de pompage

The purpose of the present study is to develop numerical tools for two-phase flow ploblems in pumping stations. Reliable simulation methods of two-phase flow are inevitable in nuclear engineering field because computer programs are important design tools for nuclear reactors which are exposed to severe ambient conditions of high temperature, high pressure and gamma ray irradiation. Mock-up tests of nuclear thermal-hydraulics are very difficult. Hitachi Ltd. has created advanced computer programs for multi-dimensional two-phase flow to analize reactor systems and components. The numerical methods enable accurate and stable interface calculation in spite of large density ratio between the phases, because non-staggered finite volume method, which is suitable for treatment of discontinuity, and minimum numerical diffusion are adopted. The multi-dimensional computer programs employ two types of two-phase flow model. The first one is the extended two-fluid model, which has capability of both interface tracking and ordinary two-fluid model calculations. This model is appropriate for the present purpose because it can treat free surface of channels and entrained bubbly mixture due to breaking waves. The second one is the improved VOF (Volume of Fluid) method in which PLIC (Piecewise Linear Interface Calculation) technique was employed. The interface state calculation is simplified by approximating cubic calculation cells to spherical ones. These computer program were applied to hydraulic studies in Hitachi Industries Co., Ltd., a vender of fluid machinery and pumping systems. It is necessary to evacuate air downstream from siphon outlets as bubble entrainment by water flow in order to operate the plant effectively after pumping station start-up. Experiments were carried out by using a reduced scale test-section. The test section was made of transparent acryl and the cross-section was rectangular. Free surface of water layer on the inclined wall and entrained bubbly mixture into the water pool due to water layer collision with free surface were observed by a video camera. The extended two-fluid model results of transient water level and pressures in the simulated siphon outlets were in good agreement with the experimental data. The predicted pressure histories at the crest and the pump site were in good agreement with the experimental data. The sedimentation in a inlet channel of a pump station was carried out. Three dimensional free surface flow was calculated by the improved VOF method and behavior of suspended sediment in the flow field is calculated. The surface wave velocity in the shallow channel was in good agreement with the theoretical one. Sediment particles had size distribution and drag force and gravity and buoyancy was taken into consideration. Critical tractive force of the sediment on floor was estimated from Schields’ correlation. The predictions of sedimentation area and suspended fraction agreed well with experimental data. These results showed that the present computer programs were able to treat key two-phase flow phenomena in pumping stations

Adjuvant chemotherapy with S-1 after curative chemoradiotherapy in patients with locoregionally advanced squamous cell carcinoma of the head and neck: Reanalysis of the ACTS-HNC study.

BACKGROUND:Chemoradiotherapy (CRT) has improved organ preservation or overall survival (OS) of locoregionally advanced head and neck squamous cell cancer (LAHNSCC), but in clinical trials of conventional CRT, increasing CRT intensity has not been shown to improve OS. In the Adjuvant ChemoTherapy with S-1 after curative treatment in patients with Head and Neck Cancer (ACTS-HNC) phase III study, OS of curative locoregional treatments improved more with adjuvant chemotherapy with S-1 (tegafur gimeracil oteracil potassium) than with tegafur/uracil (UFT). ACTS HNC study showed the significant efficacy of S-1 after curative radiotherapy in sub-analysis. We explored the efficacy of S-1 after curative CRT in a subset of patients from the ACTS-HNC study. METHODS:Patients with stage III, IVA, or IVB LAHNSCC were enrolled in this study to evaluate the efficacy of S-1 compared with UFT as adjuvant chemotherapy after curative CRT in the ACTS-HNC study. Patients received S-1 at 80-120 mg/day in two divided doses for 2 weeks, followed by a 1-week rest, or UFT 300 or 400 mg/day in two or three divided doses daily, for 1 year. The endpoints were OS, disease-free survival, locoregional relapse-free survival, distant metastasis-free survival (DMFS), and post-locoregional relapse survival. RESULTS:One hundred eighty patients (S-1, n = 87; UFT, n = 93) were included in this study. Clinical characteristics of the S-1 and UFT arms were similar. S-1 after CRT significantly improved OS (hazard ratio [HR], 0.46; 95% confidence interval [CI], 0.22-0.93) and DMFS (HR, 0.50; 95% CI, 0.26-0.97) compared with UFT. CONCLUSION:As adjuvant chemotherapy, S-1 demonstrated better efficacy for OS and DMFS than UFT in patients with LAHNSCC after curative CRT and may be considered a treatment option following curative CRT. For this study was not preplanned in the ACTS-HNC study, the results is hypothesis generating but not definitive

Randomized Phase III Trial of Adjuvant Chemotherapy with S-1 after Curative Treatment in Patients with Squamous-Cell Carcinoma of the Head and Neck (ACTS-HNC)

<div><p>Background</p><p>We conducted a phase III study to evaluate S-1 as compared with UFT as control in patients after curative therapy for stage III, IVA, or IVB squamous-cell carcinoma of the head and neck (SCCHN).</p><p>Patients and Methods</p><p>Patients were randomly assigned to the UFT group (300 or 400 mg day^-1 for 1 year) or the S-1 group (80, 100, or 120 mg day^-1 for 1 year). The primary end point was disease-free survival (DFS). Secondary end points were relapse-free survival, overall survival (OS), and safety.</p><p>Results</p><p>A total of 526 patients were enrolled, and 505 were eligible for analysis. The 3-year DFS rate was 60.0% in the UFT group and 64.1% in the S-1 group (HR, 0.87; 95%CI, 0.66-1.16; p = 0.34). The 3-year OS rate was 75.8% and 82.9%, respectively (HR, 0.64; 95% CI, 0.44-0.94; p = 0.022). Among grade 3 or higher adverse events, the incidences of leukopenia (5.2%), neutropenia (3.6%), thrombocytopenia (2.0%), and mucositis/stomatitis (2.4%) were significantly higher in the S-1 group.</p><p>Conclusions</p><p>Although DFS did not differ significantly between the groups, OS was significantly better in the S-1 group than in the UFT group. S-1 is considered a treatment option after curative therapy for stage III, IVA, IVB SCCHN.</p><p>Trial Registration</p><p><a href="http://ClinicalTrials.gov" target="_blank">ClinicalTrials.gov</a> NCT00336947 <a href="http://clinicaltrials.gov/show/NCT00336947" target="_blank">http://clinicaltrials.gov/show/NCT00336947</a></p></div

Overall survival in the CRT group.

<p>(A) OS derived from Kaplan–Meier curves. (B) HR and corresponding CI were calculated using Cox proportional hazard model. <i>P</i> values were calculated based on stratified log-rank test. Abbreviations: CI, confidence interval. HR, hazard ratio. OS, overall survival.</p

Patient characteristics.

<p>Patient characteristics.</p

Definition of definitive treatment.

<p>Abbreviations: RT, radiotherapy. CRT, chemoradiotherapy.</p

Treatment completion rates.

<p>Treatment completion rates.</p