Model based methodology development for energy recovery in ash heat exchange systems

Flash tank evaporation combined with a condensing heat exchanger can be used when heat exchange is required between two streams and where at least one of these streams is difficult to handle (in terms of solid particles content, viscosity, pH, consistency etc.). To increase the efficiency of heat exchange, a cascade of these units in series can be used. Heat transfer relationships in such a cascade are very complex due to their interconnectivity, thus the impact of any changes proposed is difficult to predict. In this report, a mathematical model of a single unit ash tank evaporator combined with a condensing heat exchanger unit is proposed. This model is then developed for a chain of the units. The purpose of this model is to allow an accurate evaluation of the effect and result of an alteration to the system. The resulting model is applied to the RUSAL Aughinish Alumina digester area

Heterogeneity in progression of prodromal features in Parkinson’s disease

Background: In the pre-diagnostic phase of Parkinson’s disease (PD), a range of motor and non-motor symptoms can occur. However, there is considerable variability in their onset and currently little information exists on the pattern of progression of clinical features before diagnosis. Methods: We analysed data from a survey amongst patients with PD from 11 European countries by the European Parkinson’s Disease Association. They completed questions on first occurrence of 21 pre-diagnostic features. A principal component analysis (PCA) with varimax rotation was performed to determine the co-occurrence of these features. Findings: 1,467 patients were included. Changes in movement were the most commonly reported features up to 4 years before diagnosis. However, at five or more years before diagnosis loss of sense of smell, sleep problems, fatigue and other non-motor features had been experienced most frequently. PCA of pre-diagnostic features’ duration revealed three factors with eigenvalues over Kaiser’s criterion of 1: a) a neuropsychiatric factor comprised of anxiety, depression, apathy, stress, and sleep problems; b) an axial factor defined by difficulty eating and/or swallowing problems, freezing, and falls/balance problems; and c) a motor factor with additional non-motor features. Bladder/bowel problems and tremor had low factor loadings on all components. However, in those with disease duration less than 5 years the autonomic features were associated with the axial factor and tremor loaded on both the motor and psychiatric symptom factors. Interpretation: The identified symptom complexes in the pre-diagnostic stage of PD may be reflective of a shared pattern of pathological disease progression

Breather decay into a vortex/anti-vortex pair in a Josephson Ladder

We present experimental evidence for a new behavior which involves discrete breathers and vortices in a Josephson Ladder. Breathers can be visualized as the creation and subsequent annihilation of vortex/anti-vortex pairs. An externally applied magnetic field breaks the vortex/anti-vortex symmetry and causes the breather to split apart. The motion of the vortex or anti-vortex creates multi-site breathers, which are always to one side or the other of the original breather depending on the sign of the applied field. This asymmetry in applied field is experimentally observed.Comment: 10 pages, 5 figure

Isolation and primary identification of shiga toxin producing Escherichia coli O157 in dairy cattle

During the last years, the significance of diseases associated etiologically to Shiga-toxin producing Escherichia coli (STEC) is continuously increasing at a global scale, while the O157 serotype is con-sidered as one of the most important pathogens of animal origin. Large ruminants play a key role in the epidemiology of E. coli diseases among men. Bovine faeces are a primary source of contamina-tion of the environment and foods with this agent. The purpose of this study was to test a specific, microbiological algorithm for primary identification of STEC isolates from bovine faeces using sorbi-tol McConkey agar supplemented with cefixime and tellurite. The attempts were focused not only on increasing the sensitivity and specificity of serotype identification, but also on optimisation of labour and analysis costs. From May 2013 to October 2014, a total number of 1104 faecal swab samples from calves 3 to 6 months of age were collected from 19 farms in different administrative and geo-graphical regions of Bulgaria. Thirty six sorbitol-negative E. coli isolates (3.26%) were detected as belonging to the O157 serotype after slide agglutination test

Industrial heat utilisation through water management

Paper presented at the 8th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Mauritius, 11-13 July, 2011.The focus of this paper is on the dependence between water and energy in industry and the way these resources can be managed in an integrated and more sustainable manner. The fundamental methodology supporting the concept of simultaneous management of water and energy is the process systems approach guided by deep understanding of the simultaneous mass and heat transfer, considering phase and pressure changes. Special attention in this case is paid to the utilisation of the latent heat of water evaporation and condensation (allowing for water and heat recycling). The paper takes a new view to water solutions management especially when processes experience difficulties for direct heat recovery. The paper also highlights the link between water management, heat recovery, process efficiency improvement and capacity de-bottlenecking, which bring additional positive impact of proposed methodologies. The advantages of efficiency improvement, water saving and improved environmental impact of proposed solutions are analysed and demonstrated on an industrial case.pm201

Field Theoretic Study of Bilayer Membrane Fusion: II. Mechanism of a Stalk-Hole Complex

We use self-consistent field theory to determine structural and energetic properties of intermediates and transition states involved in bilayer membrane fusion. In particular, we extend our original calculations from those of the standard hemifusion mechanism, which was studied in detail in the first paper of this series, to consider a possible alternative to it. This mechanism involves non-axial stalk expansion, in contrast to the axially symmetric evolution postulated in the classical mechanism. Elongation of the initial stalk facilitates the nucleation of holes and leads to destabilization of the fusing membranes via the formation of a stalk-hole complex. We study properties of this complex in detail, and show how transient leakage during fusion, previously predicted and recently observed in experiment, should vary with system architecture and tension. We also show that the barrier to fusion in the alternative mechanism is lower than that of the standard mechanism by a few $k_BT$ over most of the relevant region of system parameters, so that this alternative mechanism is a viable alternative to the standard pathway

Mass coupling and Q−1ofimpurity−limitednormalQ^{-1} of impurity-limited normal ^3$He in a torsion pendulum

We present results of the $Q^{-1}$ and period shift, $\Delta P$, for $^3$He confined in a 98% nominal open aerogel on a torsion pendulum. The aerogel is compressed uniaxially by 10% along a direction aligned to the torsion pendulum axis and was grown within a 400 $\mu$m tall pancake (after compression) similar to an Andronikashvili geometry. The result is a high $Q$ pendulum able to resolve $Q^{-1}$ and mass coupling of the impurity-limited $^3$He over the whole temperature range. After measuring the empty cell background, we filled the cell above the critical point and observe a temperature dependent period shift, $\Delta P$, between 100 mK and 3 mK that is 2.9$$ of the period shift (after filling) at 100 mK. The $Q^{-1}$ due to the $^3$He decreases by an order of magnitude between 100 mK and 3 mK at a pressure of $0.14\pm0.03$ bar. We compare the observable quantities to the corresponding calculated $Q^{-1}$ and period shift for bulk $^3$He.Comment: 8 pages, 3 figure

Supercooling of the A phase of 3He

Publisher Copyright: © 2023, The Author(s).Because of the extreme purity, lack of disorder, and complex order parameter, the first-order superfluid 3He A–B transition is the leading model system for first order transitions in the early universe. Here we report on the path dependence of the supercooling of the A phase over a wide range of pressures below 29.3 bar at nearly zero magnetic field. The A phase can be cooled significantly below the thermodynamic A–B transition temperature. While the extent of supercooling is highly reproducible, it depends strongly upon the cooling trajectory: The metastability of the A phase is enhanced by transiting through regions where the A phase is more stable. We provide evidence that some of the additional supercooling is due to the elimination of B phase nucleation precursors formed upon passage through the superfluid transition. A greater understanding of the physics is essential before 3He can be exploited to model transitions in the early universe.Peer reviewe

A lattice model for the kinetics of rupture of fluid bilayer membranes

We have constructed a model for the kinetics of rupture of membranes under tension, applying physical principles relevant to lipid bilayers held together by hydrophobic interactions. The membrane is characterized by the bulk compressibility (for expansion), the thickness of the hydrophobic part of the bilayer, the hydrophobicity and a parameter characterizing the tail rigidity of the lipids. The model is a lattice model which incorporates strain relaxation, and considers the nucleation of pores at constant area, constant temperature, and constant particle number. The particle number is conserved by allowing multiple occupancy of the sites. An equilibrium ``phase diagram'' is constructed as a function of temperature and strain with the total pore surface and distribution as the order parameters. A first order rupture line is found with increasing tension, and a continuous increase in proto-pore concentration with rising temperature till instability. The model explains current results on saturated and unsaturated PC lipid bilayers and thicker artificial bilayers made of diblock copolymers. Pore size distributions are presented for various values of area expansion and temperature, and the fractal dimension of the pore edge is evaluated.Comment: 15 pages, 8 figure

Using simulation and machine learning to maximise the benefit of intravenous thrombolysis in acute stroke in England and Wales: the SAMueL modelling and qualitative study

This is the final version. Available from the NIHR via the DOI in this record. Data were obtained from the Sentinel Stroke National Audit,19 managed through HQIP.26 SSNAP collects patient-level data on acute stroke admissions, with pre-hospital data recently added. SSNAP has near-complete coverage of all acute stroke admissions in the UK (outside Scotland) and is building up coverage of outcomes at 6 months. All hospitals admitting acute stroke participate in the audit, and year-on-year comparison with Hospital Episode Statistics27 confirms estimated case ascertainment of 95% of coded cases of acute stroke.Stroke is a common cause of adult disability. Expert opinion is that about 20% of patients should receive thrombolysis to break up a clot causing the stroke. Currently, 11–12% of patients in England and Wales receive this treatment, ranging between 2% and 24% between hospitals. Objectives: We sought to enhance the national stroke audit by providing further analysis of the key sources of inter-hospital variation to determine how a target of 20% of stroke patients receiving thrombolysis may be reached. Design: We modelled three aspects of the thrombolysis pathway, using machine learning and clinical pathway simulation. In addition, the project had a qualitative research arm, with the objective of understanding clinicians’ attitudes to use of modelling and machine learning applied to the national stroke audit. Participants and data source: Anonymised data were collected for 246,676 emergency stroke admissions to acute stroke teams in England and Wales between 2016 and 2018, obtained from the Sentinel Stroke National Audit Programme. Results: Use of thrombolysis could be predicted with 85% accuracy for those patients with a chance of receiving thrombolysis (i.e. those arriving within 4 hours of stroke onset). Machine learning models allowed prediction of likely treatment choice for each patient at all hospitals. A clinical pathway simulation predicted hospital thrombolysis use with an average absolute error of 0.5 percentage points. We found that about half of the inter-hospital variation in thrombolysis use came from differences in local patient populations, and half from in-hospital processes and decision-making. Three changes were applied to all hospitals in the model: (1) arrival to treatment in 30 minutes, (2) proportion of patients with determined stroke onset times set to at least the national upper quartile and (3) thrombolysis decisions made based on majority vote of a benchmark set of 30 hospitals. Any single change alone was predicted to increase national thrombolysis use from 11.6% to between 12.3% and 14.5% (with clinical decision-making having the most effect). Combined, these changes would be expected to increase thrombolysis to 18.3% (and to double the clinical benefit of thrombolysis, as speed increases also improve clinical benefit independently of the proportion of patients receiving thrombolysis); however, there would still be significant variation between hospitals depending on local patient population. For each hospital, the effect of each change could be predicted alone or in combination. Qualitative research with 19 clinicians showed that engagement with, and trust in, the model was greatest in physicians from units with higher thrombolysis rates. Physicians also wanted to see a machine learning model predicting outcome with probability of adverse effect of thrombolysis to counter a fear that driving thrombolysis use up may cause more harm than good. Limitations: Models may be built using data available in the Sentinel Stroke National Audit Programme only. Not all factors affecting use of thrombolysis are contained in Sentinel Stroke National Audit Programme data and the model, therefore, provides information on patterns of thrombolysis use in hospitals, but is not suitable for, or intended as, a decision aid to thrombolysis. Conclusions: Machine learning and clinical pathway simulation may be applied at scale to national audit data, allowing extended use and analysis of audit data. Stroke thrombolysis rates of at least 18% look achievable in England and Wales, but each hospital should have its own target. Future work: Future studies should extend machine learning modelling to predict the patient-level outcome and probability of adverse effects of thrombolysis, and apply co-production techniques, with clinicians and other stakeholders, to communicate model outputs.Health and Social Care Delivery Research (HSDR) Programm