•PCHE’s model Incorporating actual channels geometries have been developed.•The performance of PCHEs has been evaluated using different channel geometries.•The effects of PCHE designs on the cycle’s ...performance have been reported.•Efficient designs for the PCHE’s have been suggested that enhance the cycle’s efficiency.
Several fin configurations have been proposed in the literature to address the poor hydraulic performance associated with the PCHEs. However, the effect of the heat exchangers with proposed channel geometries on the performance of supercritical carbon dioxide(sCO2) power cycle is missing. In this context, the current study deals with the effects of different designs of the PCHEs varied by proposed channel configurations, heat exchanger’s effectiveness and design value of inlet Reynolds number on the performance of sCO2 power cycle. Moreover, a multi-object optimization study to find the best bargain between cycle’s efficiency and heat exchanger’s size is carried out using five different fin configurations (straight, zigzag, C-shaped, S-shaped, and airfoil fin channel configuration), heat exchanger’s effectiveness and inlet Reynolds number as a design variable. Results shows that enhancement in the hydraulic characteristics for a channel geometry that comes at the cost of thermal performance may not benefit the system’s efficiency. Optimization results suggest that C-shaped channel and zigzag channel geometries correspond to the cycle’s maximum efficiency and heat exchanger’s minimum size respectively. Optimization results further highlight that the comparison of channel geometries should be performed while in the setting of complete power generation cycle to account for all the variables involved.
Reliable and efficient underwater acoustic communications are challenging problems because of complex underwater channel properties. With the recent advancements in underwater technologies, there is ...a need for a robust underwater communication system which can endure high data rate and optimize the use of resources like bandwidth and time. In this work, a blind deconvolution based equalizer is proposed, which uses the received signal to compute the channel impulse response estimates and equalizes the received signal using these channel impulse response estimates. The performance of the proposed system is tested with both simulated and real data. The real data were obtained during an experiment in September 2017 in TrondheimFjord. In the case of real data, the difference in performance in terms of mean square error between the proposed equalizer and the probe-based channel estimation equalizer is only 0.68 dB. This suggests that the proposed blind deconvolution technique can provide good channel estimates to equalize the underwater channel effects. In addition to that, it can save the resources allocated for the probe signal estimation.
The use of commercialised forced oscillation (FOT) devices to assess impedance in obstructive diseases such as asthma has gained popularity. However, it has yet to be fully established whether ...resistance and reactance measurements are comparable across different FOT devices, particularly in disease. We compared two commercially available FOT devices: Impulse Oscillometry (IOS) and TremoFlo FOT (Thorasys) in a) clinical adult population of healthy controls (n = 14), asymptomatic smokers (n = 17) and individuals with asthma (n = 73) and b) a 3D printed CT-derived airway tree model resistance, as well as a 3 L standardised volume reactance. Bland-Altman Plots and linear regressions were used to evaluate bias between the devices. Resistance measurements at both 5 and 20 Hz were numerically higher with IOS compared to FOT, with evidence of small and statistically significant proportional systematic bias and a positive Bland-Altman regression slope at both 5 and 20 Hz. In contrast, the IOS device recorded reactances that were less negative at both 5 Hz and 20 Hz and significantly smaller reactance areas when compared to TremoFlo. Larger statistically significant proportional systematic biases were demonstrated with both reactance at 5 Hz and reactance area (AX) between the devices with a negative Bland-Altman regression slope. The printed airway resistance and standardised volume reactance confirmed the observations seen in patients. We have demonstrated that the impulse oscillation system and TremoFlo FOT demonstrate comparative bias, particularly when comparing airway reactance in patients. Our results highlight the need for further standardisation across FOT measurement devices, specifically using variable test loads for reactance standardisation.
Eosinophilic airway inflammation is often present in asthma, and reduction of such inflammation results in improved clinical outcomes. We hypothesised that fevipiprant (QAW039), an antagonist of ...prostaglandin D2 receptor 2, might reduce eosinophilic airway inflammation in patients with moderate-to-severe eosinophilic asthma.
We performed a single-centre, randomised, double-blind, parallel-group, placebo-controlled trial at Glenfield Hospital (Leicester, UK). We recruited patients with persistent, moderate-to-severe asthma and an elevated sputum eosinophil count (≥2%). After a 2-week single-blind placebo run-in period, patients were randomly assigned (1:1) by the trial pharmacist, using previously generated treatment allocation cards, to receive fevipiprant (225 mg twice per day orally) or placebo, stratified by the use of oral corticosteroid treatment and bronchoscopy. The 12-week treatment period was followed by a 6-week single-blind placebo washout period. The primary outcome was the change in sputum eosinophil percentage from baseline to 12 weeks after treatment, analysed in the intention-to-treat population. All patients who received at least one dose of study drug were included in the safety analyses. This trial is registered with ClinicalTrials.gov, number NCT01545726, and with EudraCT, number 2011-004966-13.
Between Feb 10, 2012, and Jan 30, 2013, 61 patients were randomly assigned to receive fevipiprant (n=30) or placebo (n=31). Three patients in the fevipiprant group and four patients in the placebo group withdrew because of asthma exacerbations. Two patients in the fevipiprant group were incorrectly given placebo (one at the mid-treatment visit and one throughout the course of the study). They were both included in the fevipiprant group for the primary analysis, but the patient who was incorrectly given placebo throughout was included in the placebo group for the safety analyses. Between baseline and 12 weeks after treatment, sputum eosinophil percentage decreased from a geometric mean of 5·4% (95% CI 3·1-9·6) to 1·1% (0·7-1·9) in the fevipiprant group and from 4·6% (2·5-8·7) to 3·9% (CI 2·3-6·7) in the placebo group. Compared with baseline, mean sputum eosinophil percentage was reduced by 4·5 times in the fevipiprant group and by 1·3 times in the placebo group (difference between groups 3·5 times, 95% CI 1·7-7·0; p=0·0014). Fevipiprant had a favourable safety profile, with no deaths or serious adverse events reported. No patient withdrawals were judged by the investigator to be related to the study drug.
Fevipiprant reduces eosinophilic airway inflammation and is well tolerated in patients with persistent moderate-to-severe asthma and raised sputum eosinophil counts despite inhaled corticosteroid treatment.
Novartis Pharmaceuticals, AirPROM project, and the UK National Institute for Health Research.
Enantioselective total synthesis of (+)-sapinsigin H, (+)-agallochaol C, and (+)-16α, 17-dihydroxy-atisan-3-one has been accomplished starting from enantiopure Wieland–Miescher ketone. Key features ...of the syntheses include a benzannulation step to construct the tricyclic core, an oxidative dearomatization step to generate the diene, and a Diels–Alder reaction with ethylene gas to establish the bicyclo2.2.2octane framework. Efficient late-stage functionalisation of the A-ring by aerobic oxidation and Baeyer−Villiger oxidation completed the atisane target molecules.
To provide a clinical rationale for including impulse oscillometry (IOS) as a part of standard office-based asthma assessment.
PubMed and Google search, limited to English language and human disease, ...with the keywords IOS and asthma.
Articles included in this review were based on the expert opinion and previous publications by the authors.
In children, IOS was more useful than spirometry in identifying asthma and uncontrolled asthma and predicting loss of control and exacerbations. IOS predicts young children at risk for loss of lung function with age and the potential for early intervention to prevent further sequelae. In adults, peripheral airway impairment detected by IOS or spirometry (ie, forced expiratory flow between 25% and 75%) commonly occurs across severity, and each measure may be complementary in predicting loss of control even with normal forced expiratory volume in 1 second. Extrafine inhaled corticosteroids with or without long-acting β-agonists proved superior to standard particle aerosols in improving IOS-detected peripheral airway obstruction. Our data also suggest that currently available commercial reference values for lung resistance at 5 Hz and lung reactance at 5 Hz are applicable across diverse populations, but further studies are needed.
The findings of this review suggest that IOS can add value to traditional clinical and spirometric assessment and thus improve management of asthma in children and adults, as well as have the potential to detect early dysfunction of the peripheral airways, which may result in better outcomes.
We present a nonintrusive approach for combining high-fidelity simulations using Finite-Volume (FV) methods with Proper Orthogonal Decomposition (POD) and Galerkin Reduced-Order Modeling (ROM) ...methodology. By nonintrusive we here imply an approach that does not need specific knowledge about the high-fidelity Computational Fluid Dynamics (CFD) solver other than the velocity and pressure results given on an element mesh representing the related discrete interpolation spaces. The key step in the presented approach is the projection of the FV results onto suitable finite-element (FE) spaces and then use of classical POD Galerkin ROM framework. We do a numerical investigation of aerodynamic flow around an airfoil cross-section (NACA64) at low Reynolds number and compare the ROM results obtained with high-fidelity FV-generated snapshots against similar high-fidelity results obtained with FE using Taylor–Hood velocity and pressure spaces. Our results show that we achieve relative errors in the range of 1–10% in both H 1 -seminorm of the computed velocities and in the L 2 -norm of the computed pressure with reasonably few ROM modes. Similar accuracy was obtained for lift and drag.
Underwater sound propagation is very sensitive to geometric and environmental variations. The geometric variations are the motion of the source and/or receiver, while the environmental variations are ...due to surface motion and water column variations. In order to reduce the effects of these variations, it is necessary to understand their effects on sound propagation. In this paper, some water column variations are reported, and their effect on the underwater sound propagation is studied. These water column variations were observed during an experiment in the TrondheimFjord on 22 September 2016. Strong amplitude variations were observed in the channel impulse response during the experiment. The Doppler analysis was performed on the channel impulse response, which showed strong Doppler variations. The amplitude and Doppler variations suggested the presence of water column variations. To demonstrate the performance of the communication system, the time reversal combiner was implemented. The system performance was demonstrated by computing the mean squared error between the transmitted signal and the output of the combiner. The performance of the combiner degraded by ~2.5 dB in the presence of water column variations. Due to these variations, the amplitudes of the arrivals changed rapidly, which posed a great challenge for the time reversal combiner. These amplitude variations affected the focusing of the combiner and hence induced intersymbol interference and performance degradation. This work provides an insight into the effects of water column variations on underwater sound propagation and underwater acoustic communications.
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