Constant Rate of Momentum Change Ejector: simulation, experiments and flow visualisation

An ejector is a momentum-transfer device that requires no external mechanical input or moving parts. However, ejectors have low performance due to irreversibilities such as viscous losses and shocks in the primary stream and diffuser. It has previously been argued that by maintaining a constant rate of momentum change along the ejector duct, shock losses could be eliminated or at least minimised, and so the Constant Rate of Momentum Change (CRMC) ejector was introduced. The CRMC configuration appears to have significant potential, but the CRMC design prescription relies on: (1) an arbitrary choice for the constant rate of momentum change along the length of the duct; and (2) complete mixing between primary and secondary streams at the entrance to the duct. This thesis investigates the themes of shock losses and mixing within a CRMC ejector using physical experiments and computational simulation. The CRMC ejector duct and the primary nozzle were manufactured using 3D printing technology and then an experimental test bench using air as the working fluid was assembled and successfully tested. The primary nozzle had a throat diameter of 3.2mm and an exit diameter of 13.6 mm; the CRMC duct had a throat diameter of 25.48 mm. Extensive experimental tests were carried out for primary pressure between 200 kPa and 270 kPa, and secondary pressure between 0.6 kPa and 5 kPa. The results demonstrate the primary nozzle exit position within the entrainment region has a limited effect on the ejector performance in terms of the entrainment ratio and critical back pressures. A gas dynamic model was used to compare the performance of the present CRMC ejector with different ejector profiles (both conventional and CRMC) working with different fluids. The CRMC ejector showed a slightly better performance in terms of entrainment ratio and compression ratio. When CFD simulations of the present CRMC ejector were compared with a conventional ejector at a similar operating condition, the total pressure of the CRMC ejector remained 15% larger than the conventional ejector but this higher performance was due to different primary flow shock structures, not due to improvements in the compression process within the diffuser. Differences in the primary flow structure are thought to be caused by the different contraction angle of the secondary flow area. Higher entrainment ratio and compression ratio were simulated for the CRMC ejector relative to the conventional ejector but were not as high as expected from the CRMC design. To investigate the mixing of the flow within the CRMC ejector, a laser-based visualization technique was developed. A transparent CRMC ejector test section was designed, fabricated, and operated in the ejector system using air as the working fluid. The laser-based flow visualisation used a laser light beam of diameter of 1mm to illuminate the seeded secondary flow and thus, the unmixed primary flow was defined. The wall static pressure of the seeded flow agrees well with that of the unseeded flow which indicates that the seeding has a very small effect on the flow. Analysis of the images by digital image processing tools enabled identification of the jet core flow length which was found to lie between 65mm and 95mm from the nozzle exit at the selected operating conditions. The primary and secondary flows entering the CRMC duct are certainly not fully mixed as assumed in the CRMC design prescription. Furthermore, enhancement of the distribution of the wall static pressure and centreline total pressure is not directly attributable to the CRMC prescription. The modest performance improvements associated with the present CRMC design relative to the performance of a conventional duct should be balanced against the added complexity associated with manufacturing a CRMC duct when considering the CRMC design for future applications

Cloud-based applications for manufacturing SMEs: A model to analyse critical cloud adoption barriers

Poster presented at Cranfield University’s 2019 Manufacturing Doctoral Community event

Transpleural systemic artery-pulmonary artery communications in the absence of chronic inflammatory lung disease. A case series and review of the literature

AIM: To describe the causes and computed tomography (CT) and angiographic appearances of transpleural systemic artery-pulmonary artery shunts in patients without chronic inflammatory lung disease and determine their best management. MATERIALS AND METHODS: All patients referred to a tertiary referral unit between January 2013 and January 2020 in whom a diagnosis of a systemic-pulmonary artery communication without underlying chronic inflammatory lung disease was subsequently made have been included in this report. Medical records and imaging findings were reviewed retrospectively. RESULTS: Ten patients (male: female ratio = 7:3; median age 42 years [range 22-70 years]) with systemic artery-pulmonary artery shunts without chronic inflammatory lung disease were identified. Five were misdiagnosed as having a pulmonary arteriovenous malformation and had been referred for embolisation. In six patients, there was either a history of accidental or iatrogenic thoracic trauma or of inflammatory disease involving the pleura, and in two patients, in whom a previous medical history could not be obtained, there were CT features suggesting previous pleural inflammatory disease. Two shunts were thought to be congenital. All individuals were asymptomatic other than one with localised thoracic discomfort that dated from the time of surgery. All patients were managed conservatively and have remained well with a median follow-up of 4.5 years (range 1-11.3 years). CONCLUSIONS: Localised transpleural systemic artery-pulmonary artery shunts in the absence of chronic inflammatory lung disease are usually related to previous thoracic trauma/intervention or abdominal or pulmonary sepsis involving a pleural or diaphragmatic surface. Congenital shunts are rare. The present study and much of the literature supports conservative management

Prevalence of ‘pouch failure’ of the ileoanal pouch in ulcerative colitis: A systematic review and meta-analysis

Background and aims The ileoanal pouch (IPAA) provides patients with ulcerative colitis (UC) that have not responded to medical therapy an option to retain bowel continuity and defecate without the need for a long-term stoma. Despite good functional outcomes, some pouches fail, requiring permanent diversion, pouchectomy, or a redo pouch. The incidence of pouch failure ranges between 2 and 15% in the literature. We conducted a systematic review and meta-analysis aiming to define the prevalence of pouch failure in patients with UC who have undergone IPAA using population-based studies. Methods We searched Embase, Embase classic and PubMed from 1978 to 31st of May 2021 to identify cross-sectional studies that reported the prevalence of pouch failure in adults (≥ 18 years of age) who underwent IPAA for UC. Results Twenty-six studies comprising 23,389 patients were analysed. With < 5 years of follow-up, the prevalence of pouch failure was 5% (95%CI 3–10%). With ≥ 5 but < 10 years of follow-up, the prevalence was 5% (95%CI 4–7%). This increased to 9% (95%CI 7–16%) with ≥ 10 years of follow-up. The overall prevalence of pouch failure was 6% (95%CI 5–8%). Conclusions The overall prevalence of pouch failure in patients over the age of 18 who have undergone restorative proctocolectomy in UC is 6%. These data are important for counselling patients considering this operation. Importantly, for those patients with UC being considered for a pouch, their disease course has often resulted in both physical and psychological morbidity and hence providing accurate expectations for these patients is vital

Mina Alsafi_Girls* on Rock 2024 Evidence

Girls* on Rock is a 12-day rock climbing and backcountry wilderness expedition for high school girls* (including female-identifying and non-binary youth). Learners engage in scientific inquiry and artistic exploration while camping, hiking, and rock climbing in the Rocky Mountains. In small groups, the participants design and carry out research projects. They then deliver their findings to a public audience. Throughout the expedition, participants engage in various art forms, exploring the various ways to tell a story. Learners demonstrate leadership skills such as communication and conflict resolution and wilderness skills such as setting up camp, navigation, and rock climbing. Evidence required to earn micro-credential includes research presentation, self-reflection, and skills checklist.</p

Mina Alsafi_Girls* on Rock Research Presentation - Flowers’ Impact on Nitrogen in the Soil

At Wheeler Lake the soil showed evidence that it impacted plant life. This called for more research to investigate more about the specific contents in the soils with different plants involved.</p

Glycogen synthase kinases 3α and 3β in cardiac myocytes: regulation and consequences of their inhibition

Inhibition of glycogen synthase kinase 3β (GSK3β) as a consequence of its phosphorylation by protein kinase B/Akt (PKB/Akt) has been implicated in cardiac myocyte hypertrophy in response to endothelin-1 or phenylephrine. We examined the regulation of GSK3α (which we show to constitute a significant proportion of the myocyte GSK3 pool) and GSK3β in cardiac myocytes. Although endothelin increases phosphorylation of GSK3 and decreases its activity, the response is less than that induced by insulin (which does not promote cardiac myocyte hypertrophy). GSK3 phosphorylation induced by endothelin requires signalling through the extracellular signal-regulated kinase 1/2 (ERK1/2) cascade and not the PKB/Akt pathway, whereas the reverse is true for insulin. Cardiac myocyte hypertrophy involves changes in morphology, and in gene and protein expression. The potent GSK3 inhibitor 1-azakenpaullone increases myocyte area as a consequence of increased cell length whereas phenylephrine increases both length and width. Azakenpaullone or insulin promotes AP1 transcription factor binding to an AP1 consensus oligonucleotide, but this was significantly less than that induced by endothelin and derived principally from increased binding of JunB protein, the expression of which was increased. Azakenpaullone promotes significant changes in gene expression (assessed by Affymetrix microarrays), but the overall response is less than with endothelin and there is little overlap between the genes identified. Thus, although GSK3 may contribute to cardiac myocyte hypertrophy in some respects (and presumably plays an important role in myocyte metabolism), it does not appear to contribute as significantly to the response induced by endothelin as has been maintained