48 research outputs found
MAXIMUM VOLUME-TO-STRESS RATIO FOR A TWO-RADII-CONTOUR DIAPHRAGM PUMP
Analytical methods were employed to determine the maximum volume-to- stress ratio for a two-radii-contour diaphragm pump. A proposed failure criterion considers the effect of biaxial stresses on fatigue failure through. the use of the Mises-Hencky criterion for fatigue failure. By use of the proposed criterion, it was determined that an optimunn ratio of the two radii does exist, its value being dependent on the ratio of diphragm thickness to diaphragm deflection. Values for the optimum ratio of the two radii (where the ratio of radii is defined as the radius of the central pcrtion of the diaphragm contour divided by the radius of the outer pontion of the diaphragm) range from 1.94 to 7.33 as the ratio of diaphragm thickness to diaphragm deflection varies from 0.5 to 0.05, respectively. (auth
Recommended from our members
High Flux Isotope Reactor power upgrade status
A return to 100-MW operation is being planned for the High Flux Isotope Reactor (HFIR). Recent improvements in fuel element manufacturing procedures and inspection equipment will be exploited to reduce hot spot and hot streak factors sufficiently to permit the power upgrade without an increase in primary coolant pressure. Fresh fuel elements already fabricated for future use are being evaluated individually for power upgrade potential based on their measured coolant channel dimensions
Nonprofit governance: Improving performance in troubled economic times
Nonprofit management is currently pressured to perform effectively in a weak economy. Yet, nonprofit governance continues to suffer from unclear conceptions of the division of labor between board of directors and executive directors. This online survey of 114 executive directors aims to provide clarification and recommendations for social administration
Gastrazole (JB95008), a novel CCK2/gastrin receptor antagonist, in the treatment of advanced pancreatic cancer: results from two randomised controlled trials
Gastrin has been shown to be a growth stimulant in pancreatic cancer cells. Gastrazole is a potent and selective gastrin receptor antagonist. Two randomised blinded trials were conducted to assess the effect of gastrazole in advanced pancreatic cancer. Patients with biopsy-proven, inoperable pancreatic carcinoma were recruited. Trial A compared protracted venous infusion (PVI) gastrazole with PVI placebo, whereas trial B compared PVI gastrazole with PVI fluorouracil (5-FU). Eighteen patients were randomised in trial A. Gastrazole produced significantly better survival compared to placebo (median 7.9 months vs 4.5 months; 1-year survival: 33 vs 11%, respectively; log rank P=0.02). No difference in toxicity was seen between gastrazole and placebo, except central venous catheter and pump complications. Ninety-eight patients were randomised in trial B. No significant survival difference was detected between gastrazole and 5-FU (median: 3.6 vs 4.2 months; 1-year survival: 13.2 vs 26.2%, respectively; log rank P=0.42). Toxicity of gastrazole was mild with significantly less diarrhoea (P=0.03), stomatitis (P<0.001) and handβ foot syndrome (P<0.001) compared to 5-FU. Quality of life (QoL) assessment showed similar QoL between gastrazole and 5-FU at baseline and no significant differences occurred with treatment either between arms or within arms. Compared to placebo, patients with advanced pancreatic cancer treated with gastrazole appeared to live longer, albeit in a very small trial and will require confirmation with large-scale randomised data. However, it did not produce survival advantage over PVI 5-FU. Lack of toxicity for gastrazole may allow its combination with cytotoxic drugs
Deletion of toxinβantitoxin systems in the evolution of Shigella sonnei as a host-adapted pathogen
Recommended from our members
Maximum Volume-to-Stress Ratio for a Two-Radii-Contour Diaphragm Pump
Analytical methods were employed to determine the maximum volume-to- stress ratio for a two-radii-contour diaphragm pump. A proposed failure criterion considers the effect of biaxial stresses on fatigue failure through. the use of the Mises-Hencky criterion for fatigue failure. By use of the proposed criterion, it was determined that an optimunn ratio of the two radii does exist, its value being dependent on the ratio of diphragm thickness to diaphragm deflection. Values for the optimum ratio of the two radii (where the ratio of radii is defined as the radius of the central pcrtion of the diaphragm contour divided by the radius of the outer pontion of the diaphragm) range from 1.94 to 7.33 as the ratio of diaphragm thickness to diaphragm deflection varies from 0.5 to 0.05, respectively. (auth
A Reassessment of PWR Pressure Vessel Integrity During Overcooling Accidents, Considering 3-D Flaws
Recommended from our members
A probabilistic approach to the evaluation of the PTS (pressurized thermal shock) issue
The pressurized-thermal-shock (PTS) issue is concerned with the possibility of failure of pressurized-water-reactor (PWR) pressure vessels under a very specific set of conditions. These conditions include: (1) the occurrence of reactor transients that subject the vessel to severe thermal shock as well as the normal pressure loading, (2) the existence of sharp, crack-like defects (flaws) at the inner surface of the vessel wall, and (3) high enough fast neutron fluence and concentrations of copper and nickel in the vessel wall to result in a extensive radiation-included reduction in the fracture toughness of the vessel material. Under these conditions, the mechanism for vessel failure involves propagation of the flaws through the vessel wall, in which case adequate containment of coolant for the core might not be possible. The portion of the vessel of concern is the so-called beltline region because, it is directly opposite the core (high influence rate), it is adjacent to the coolant downcomer (potential for thermal shock), and coolant leakage in this area would tend to uncover the core. This document discusses the behavior of flaws in reactor pressure vessels under pressure and thermal-shock loading conditions