4 research outputs found
Linear friction weld process monitoring of fixture cassette deformations using empirical mode decomposition
Due to its inherent advantages, linear friction welding is a solid-state joining process of increasing importance to the aerospace, automotive, medical and power generation equipment industries. Tangential oscillations and forge stroke during the burn-off phase of the joining process introduce essential dynamic forces, which can also be detrimental to the welding process. Since burn-off is a critical phase in the manufacturing stage, process monitoring is fundamental for quality and stability control purposes. This study aims to improve workholding stability through the analysis of fixture cassette deformations. Methods and procedures for process monitoring are developed and implemented in a fail-or-pass assessment system for fixture cassette deformations during the burn-off phase. Additionally, the de-noised signals are compared to results from previous production runs. The observed deformations as a consequence of the forces acting on the fixture cassette are measured directly during the welding process. Data on the linear friction-welding machine are acquired and de-noised using empirical mode decomposition, before the burn-off phase is extracted. This approach enables a direct, objective comparison of the signal features with trends from previous successful welds. The capacity of the whole process monitoring system is validated and demonstrated through the analysis of a large number of signals obtained from welding experiments
A hidden crisis: strengthening the evidence base on the current failures of rural groundwater supplies
New ambitious international goals for universal access to safe drinking water depend critically on the ability of development partners to accelerate and sustain access to groundwater. However, available evidence (albeit fragmented and methodologically unclear) indicates >30% of new groundwater-based supplies are non-functional within a few years of construction. Critically, in the absence of a significant systematic evidence base or analysis on supply failures, there is little opportunity to learn from past mistakes, to ensure more sustainable services can be developed in the future. This work presents a new and robust methodology for investigating the causes of non-functionality, developed by an interdisciplinary team as part of an UPGro catalyst grant. The approach was successfully piloted within a test study in NE Uganda, and forms a basis for future research to develop a statistically significant systematic evidence base to unravel the underlying causes of failure
Additional file 1: of The effect of universal maternal antenatal iron supplementation on neurodevelopment in offspring: a systematic review and meta-analysis
Part 1: Demonstration of search strategy for Medline; Part 2: Summary of the selected studies. (DOCX 24 kb
Double blind, randomised, placebo controlled study of a platelet activating factor antagonist, lexipafant, in the treatment and prevention of organ failure in predicted severe acute pancreatitis
Background—Platelet activating factor
(PAF) is believed to amplify the activity of
key mediators of the systemic inflammatory response syndrome (SIRS) in acute
pancreatitis, resulting in multiorgan dysfunction syndrome. We tested the hypothesis that a potent PAF antagonist,
lexipafant, could dampen SIRS and reduce organ failure in severe acute pancreatitis.
Methods—We conducted a randomised,
double blind, placebo controlled, multicentre trial of lexipafant (100 mg/24 hours
intravenously for seven days commenced
within 72 hours of the onset of symptoms)
involving 290 patients with an APACHE II
score >6. Power calculations assumed that
complications would be reduced from 40%
to 24%. Secondary end points studied
included severity of organ failure, markers of the inflammatory response, and
mortality rate.
Findings—Overall, 80/138 (58%) patients
in the placebo group and 85/148 (57%) in
the lexipafant group developed one or
more organ failures. The primary hypothesis was invalidated by the unexpected
finding that 44% of patients had organ
failure on entry into the study; only 39
(14%) developed new organ failure. Organ
failure scores were reduced in the lexipafant group only on day 3: median change
−1 (range −4 to +8) versus 0 (−4 to +10) in
the placebo group (p=0.04). Systemic sepsis affected fewer patients in the lexipafant
group (13/138 v 4/148; p=0.023). Local
complications occurred in 41/138 (30%)
patients in the placebo group and in 30/148
(20%) in the lexipafant group (20%;
p=0.065); pseudocysts developed in 19
(14%) and eight (5%) patients, respectively (p=0.025). Deaths attributable to
acute pancreatitis were not significantly
different. Interleukin 8, a marker of
neutrophil activation, and E-selectin, a
marker of endothelial damage, decreased
more rapidly in the lexipafant group (both
p<0.05); however, absolute values were not
different between the two groups.
Interpretation—The high incidence of
organ failure within 72 hours of the onset
of symptoms undermined the primary
hypothesis, and power calculations for
future studies in severe acute pancreatitis
will need to allow for this. Lexipafant had
no effect on new organ failure during
treatment. This adequately powered study
has shown that antagonism of PAF activity
on its own is not sufficient to ameliorate
SIRS in severe acute pancreatitis