A novel framework for enhancing marine dual fuel engines environmental and safety performance via digital twins

The Internet of Things (IoT) advent and digitalisation has enabled the effective application of the digital twins (DT) in various industries, including shipping, with expected benefits on the systems safety, efficiency and environmental footprint. The present research study establishes a novel framework that aims to optimise the marine DF engines performance-emissions trade-offs and enhance their safety, whilst delineating the involved interactions and their effect on the performance and safety. The framework employs a DT, which integrates a thermodynamic engine model along with control function and safety systems modelling. The DT was developed in GT-ISE© environment. Both the gas and diesel operating modes are investigated under steady state and transient conditions. The engine layout is modified to include Exhaust Gas Recirculation (EGR) and Air Bypass (ABP) systems for ensuring compliance with ‘Tier III’ emissions requirements. The optimal DF engine settings as well as the EGR/ABP systems settings for optimal engine efficiency and reduced emissions are identified in both gas and diesel modes, by employing a combination of optimisation techniques including multi-objective genetic algorithms (MOGA) and Design of Experiments (DoE) parametric runs. This study addresses safety by developing an intelligent engine monitoring and advanced faults/failure diagnostics systems, which evaluates the sensors measurements uncertainty. A Failure Mode Effects and Analysis (FMEA) is employed to identify the engine safety critical components, which are used to specify operating scenarios for detailed investigation with the developed DT. The integrated DT is further expanded, by establishing a Faulty Operation Simulator (FOS) to simulate the FMEA scenarios and assess the engine safety implications. Furthermore, an Engine Diagnostics System (EDS) is developed, which offers intelligent engine monitoring, advanced diagnostics and profound corrective actions. This is accomplished by developing and employing a Data-Driven (DD) model based on Neural Networks (NN), along with logic controls, all incorporated in the EDS. Lastly, the manufacturer’s and proposed engine control systems are combined to form an innovative Unified Digital System (UDS), which is also included in the DT. The analysis of marine (DF) engines with the use of an innovative DT, as presented herein, is paving the way towards smart shipping.The Internet of Things (IoT) advent and digitalisation has enabled the effective application of the digital twins (DT) in various industries, including shipping, with expected benefits on the systems safety, efficiency and environmental footprint. The present research study establishes a novel framework that aims to optimise the marine DF engines performance-emissions trade-offs and enhance their safety, whilst delineating the involved interactions and their effect on the performance and safety. The framework employs a DT, which integrates a thermodynamic engine model along with control function and safety systems modelling. The DT was developed in GT-ISE© environment. Both the gas and diesel operating modes are investigated under steady state and transient conditions. The engine layout is modified to include Exhaust Gas Recirculation (EGR) and Air Bypass (ABP) systems for ensuring compliance with ‘Tier III’ emissions requirements. The optimal DF engine settings as well as the EGR/ABP systems settings for optimal engine efficiency and reduced emissions are identified in both gas and diesel modes, by employing a combination of optimisation techniques including multi-objective genetic algorithms (MOGA) and Design of Experiments (DoE) parametric runs. This study addresses safety by developing an intelligent engine monitoring and advanced faults/failure diagnostics systems, which evaluates the sensors measurements uncertainty. A Failure Mode Effects and Analysis (FMEA) is employed to identify the engine safety critical components, which are used to specify operating scenarios for detailed investigation with the developed DT. The integrated DT is further expanded, by establishing a Faulty Operation Simulator (FOS) to simulate the FMEA scenarios and assess the engine safety implications. Furthermore, an Engine Diagnostics System (EDS) is developed, which offers intelligent engine monitoring, advanced diagnostics and profound corrective actions. This is accomplished by developing and employing a Data-Driven (DD) model based on Neural Networks (NN), along with logic controls, all incorporated in the EDS. Lastly, the manufacturer’s and proposed engine control systems are combined to form an innovative Unified Digital System (UDS), which is also included in the DT. The analysis of marine (DF) engines with the use of an innovative DT, as presented herein, is paving the way towards smart shipping

Cardiovascular morbidity and mortality after kidney transplantation

Kidney transplantation is the optimal treatment for patients with end stage renal disease (ESRD) who would otherwise require dialysis. Patients with ESRD are at dramatically increased cardiovascular (CV) risk compared to the general population. As well as improving quality of life, successful transplantation accords major benefits by reducing cardiovascular risk in these patients. Worldwide, cardiovascular disease remains the leading cause of death with a functioning graft and therefore is a leading cause of graft failure. This review focuses on the mechanisms underpinning excess cardiovascular morbidity and mortality and current evidence for improving cardiovascular risk in kidney transplant recipients. Conventional cardiovascular risk factors such as hypertension, diabetes mellitus, dyslipidaemia, and pre-existing ischaemic heart disease are all highly prevalent in this group. In addition, kidney transplant recipients exhibit a number of risk factors associated with pre-existing renal disease. Furthermore, complications specific to transplantation may ensue includingreduced graft function, side effects of immunosuppression and post transplantation diabetes mellitus. Strategies to improve cardiovascular outcomes post transplantation may include pharmacological intervention including lipid lowering or antihypertensive therapy, optimisation of graft function, lifestyle intervention and personalising immunosuppression to the individual patients risk profile

Should we ligate arteriovenous fistulas in asymptomatic patients after kidney transplantation?

No abstract available

Studies of the vasculopathy of Chronic Kidney Disease using iron-enhanced and cardiac Magnetic Resonance Imaging

Use of conventional contrast agents, both iodinated or gadolinium-based, in patients with late-stage chronic kidney disease (CKD) are limited by the risks for additional acute kidney injury and nephrogenic systemic fibrosis (NSF), respectively, that must be balanced by the critical nature of the radiologic study for the well being of the patient. In addition, current techniques have reduced accuracy for arterial diagnosis in the presence of arteriosclerotic calcification or have limitations in assessing peripheral and central vein patency. To overcome these challenges we examined whether ferumoxytol-based vascular magnetic resonance imaging (MRI) can offer a practical solution to both gadolinium-based and iodinated contrast agents when assessing vessel anatomy. We focused on two district groups of patients: a) kidney transplant candidates and b) patients requiring vascular access creation for haemodialysis. Kidney transplantation is the treatment of choice for suitable patients with end-stage renal disease (ESRD) with around 90 000 kidney transplants performed every year worldwide. Approximately 25% of patients with CKD have evidence of peripheral arterial disease (PAD) on non-invasive studies. Even though PAD does not preclude transplantation, revascularisation procedures may be required before listing. Characterisation of PAD in kidney transplant candidates relies on history, physical examination and imaging studies. Imaging studies with vascular mapping, including computed tomography angiography (CTA), provide precise preoperative anatomy of vascular and extravascular systems allowing the surgeon to determine if kidney transplantation is possible, whether presurgical procedures are necessary, and the best surgical technique for each candidate. Until now the widespread use of CTA in the workup of potential kidney transplant recipients has been limited because of the perceived increased risk of nephrotoxicity in patients with residual renal function. Preoperative sonographic mapping of arm vessels is essential for creating permanent haemodialysis access and used for arterial and venous evaluation to optimise arteriovenous fistula (AVF) placement. But Duplex ultrasound (US) is limited by an inherent operator-dependence, the inability to provide direct evidence of central stenosis and the lack of image manipulation and reconstruction to inform the surgeon about vascular anatomical course and tortuosity. Contrast-enhanced MR angiography provides excellent visualisation of both central and upper extremity vessels. However, the risk of NSF in advanced CKD has curtailed its use in arteriovenous access planning. The alternative option of traditional iodinated contrast-based CT angiography risks nephrotoxicity in patients with residual renal function. Arteriovenous fistula is considered the preferred type of access for maintenance haemodialysis, however it may contribute to maladaptive cardiovascular remodelling. The creation of an AVF leads to a localised area of high flow shunting of blood from the arterial to venous circulation, and exposes the low pressure, high capacitance venous system to the high pressure, low capacitance arterial system. Immediately following creation, AVF is associated with an increase in cardiac output, predominantly as a consequence of reduced systemic vascular resistance, increased myocardial contractility, and an increase in stroke volume and heart rate. Over time, because of the increase in blood volume, the right atrial pressure, pulmonary artery pressure, and left ventricular (LV) end-diastolic pressure gradually increase until the myocardium decompensates, the LV dilates, the ejection fraction declines, and the patient has symptoms of heart failure. Ferumoxytol has been increasingly used for MR angiography, particularly for patients with CKD. Ferumoxytol is a carbohydrate-coated ultra-small paramagnetic iron oxide approved for intravenous treatment of iron deficiency anaemia. However, ferumoxytol was originally designed as an intravascular contrast agent for MRI, and therefore, has powerful imaging attributes not present in other intravenous iron products nor the extracellular gadolinium-based contrast agents. A large molecular weight of 750 kD for ferumoxytol delays contrast extravasation, allowing slow administration or application before the patient is transferred to the MRI suite. The glomerulus does not filter ferumoxytol. Removal of ferumoxytol occurs via circulating macrophages with the remaining iron oxide particles taken up by the reticuloendothelial system of the liver, spleen and bone marrow. Given its half-life of approximately 15 hours, ferumoxytol allows enhancement of both the arterial and venous vasculature without the need for bolus timing. As part of this thesis, we have applied novel techniques using ferumoxytol-enhanced MR angiography (FeMRA) whilst planning transplantation or haemodialysis in two comparative cohort studies. To optimise our MRI protocol and ferumoxytol dosing regime, we also performed preliminary feasibility and dose-finding studies. The first cohort included patients undergoing CTA of iliac vasculature prior to listing for kidney transplantation. The second cohort included patients undergoing US vascular mapping prior to upper limb AVF creation for haemodialysis. A third cohort consisted of study participants in the second cohort who underwent cardiac magnetic resonance imaging (CMR) at baseline and 6 weeks after AVF surgery to assess changes in cardiovascular anatomical and functional parameters. We compared outcomes of interest including quality of image and diagnostic accuracy in a head-to-head design between CTA or Duplex US and FeMRA. For the CMR study, changes in outcomes of interest from baseline to follow-up scans were assessed. All three studies are briefly discussed below. In a prospective study of 36 kidney transplant candidates, FeMRA was compared with CTA for assessment of arterial and vein diameter, calcification, and signal. FeMRA was comparable to CTA for evaluating arterial diameter and calcification and offered improved venous depiction. Two transplant surgeons identified vein abnormalities critical to venous anastomosis planning in 11% of patients with FeMRA. These findings favor FeMRA and could improve clinical practice. In a prospective study of 59 participants with CKD requiring upper limb vascular mapping, FeMRA identified 15 central vessel stenoses and characterised 37% of arterial sections as unsuitable for AVF creation compared with 26% for Duplex US (p = 0.01). Ferumoxytol-enhanced MR angiography independently predicted successful fistula outcome for models including and excluding central vasculature. Compared with Duplex US, FeMRA had superior detection of central vein stenosis and arterial disease that correlated with outcomes of arteriovenous fistula surgery for haemodialysis. In a prospective study of 40 participants who underwent CMR imaging before and an average time of 6.4 weeks after AVF creation, a mean increase of 7.4 g (p = 0.02) was observed in LV myocardial mass. The changes were more pronounced in high blood flow arteriovenous fistulas (15.5 g, p = 0.003). Significant increases in LV end-diastolic volumes, cardiac output, and cardiac index were also seen after AVF creation (p < 0.04). These data support further investigation of the impact of routine AVF creation in CKD patients on clinical outcomes. Our results demonstrate that ferumoxytol-enhanced MR angiography is a robust method for vascular mapping of patients with advanced CKD with similar or higher yield compared with the currently employed imaging techniques. Ferumoxytol’s favorable pharmacodynamics allows imaging of predialysis patients without concerns for iodine or gadolinium contrast toxicity

Stability upgrade of a typical Philippine ferry

The waterborne transport in the Philippines has been a sensitive subject amplified by the lack of rules and regulations to restrict ship-owners profit-driven decisions, leading to overloading, with significant impact on ship stability. Most of the Tier-II vessels are using solid ballast to balance trim and increase static stability at the expense of freeboard. To improve matters whilst facilitating the currently adopted process, solutions are required that offer additional buoyancy with increased stability. To this end, a solution is proposed here through the addition of sponsons, providing the required level of intact stability and residual floatability/stability, using a typical Ro-Pax. In this paper, a case study is presented to demonstrate the validity of the proposed solution

A novel methodology for marine dual fuel engines sensors diagnostics and health management

The sensors abnormalities, faults, failure detection and diagnosis for marine engines are considered crucial for ensuring the engine safe and smooth operation. The development of such system(s) is typically based on the manufacturers experience on sensors and actuators faults and failure events. This study aims to introduce a novel methodology for the sensors diagnostics and health management in marine dual fuel engines by employing a combination of thermodynamic, functional control and data-driven models. The concept of an Engine Diagnostics System (EDS) is developed to provide intelligent engine monitoring, advanced sensors' faults detection as well as timely and profound corrective actions. This system employs a neural networks (NN) Data-Driven (DD) model along with appropriate logic controls. The DD model is set up based on the derived steady state data from a thermodynamic model of high fidelity and is capable of real-time prediction of the engine health condition behaviour. The concept of a novel Unified Digital System (UDS) is proposed that combines the engine's existing control and diagnostic systems with the EDS. The functionality of the UDS system is validated by employing a digital twin of the considered marine dual fuel engine by investigating scenarios for assessing the engine performance that entail abnormalities in the engine’s speed and boost pressure sensors. The simulation results demonstrate that the developed UDS is capable of sufficiently capturing the engine’s sensors abnormalities and applying appropriate corrective actions to restore the engine operation in its original state. This study benefits the development future systems facilitating the engines condition assessment and self-correction of the engine sensors' abnormalities, which will be required for smart and autonomous shipping

Towards marine dual fuel engines digital twins - integrated modelling of thermodynamic processes and control system functions

This study aims at developing an integrated model that combines detailed engine thermodynamic modelling and the control system functional modelling paving the way towards the development of fidel digital twins. To sufficiently represent the combustion process, a multi-Wiebe function approach was employed along with a database for storing the Wiebe functions parameters and the use of quadratic interpolation. The developed model was employed for the systematic investigation of a marine four-stroke dual fuel engine response during demanding transient operation with modes switching and load changes. The derived results are analysed for identifying the engine critical components and their effect on the engine operational limitations. The results demonstrate that the developed model can sufficiently represent the engine and its subsystems/components behaviour and effectively capture the engine control systems functionality. The appropriate turbocharger matching along with the sufficient design of the exhaust gas waste gate valve and fuels control systems are crucial for ensuring the smooth engine operation of dual fuel engines

Continued monitoring of acute kidney injury survivors might not be necessary in those regaining an estimated glomerular filtration rate > 60 mL/min at 1 year

Background. Severe acute kidney injury (AKI) among hospitalized patients often necessitates initiation of short-term dialysis. Little is known about the long-term outcome of those who recover to normal renal function. The aim of this study was to determine the long-term renal outcome of patients experiencing AKI requiring dialysis secondary to hypoperfusion injury and/or sepsis who recovered to apparently normal renal function. Methods. All adult patients with AKI requiring dialysis in our centre between 1 January 1980 and 31 December 2010 were identified. We included patients who had estimated glomerular filtration rate (eGFR) &gt;60 mL/min/1.73 m2 12 months or later after the episode of AKI. Patients were followed up until 3 March 2015. The primary outcome was time to chronic kidney disease (CKD) (defined as eGFR persistently &lt;60 mL/min/1.73 m2) from first dialysis for AKI. Results. Among 2922 patients with a single episode of dialysis-requiring AKI, 396 patients met the study inclusion criteria. The mean age was 49.8 (standard deviation 16.5) years and median follow-up was 7.9 [interquartile range (IQR) 4.8–12.7] years. Thirty-five (8.8%) of the patients ultimately developed CKD after a median of 5.3 (IQR 2.8–8.0) years from first dialysis for AKI giving an incidence rate of 1 per 100 person-years. Increasing age, diabetes and vascular disease were associated with higher risk of progression to CKD [adjusted hazard ratios (95% confidence interval): 1.06 (1.03, 1.09), 3.05 (1.41, 6.57) and 3.56 (1.80, 7.03), respectively]. Conclusions. Recovery from AKI necessitating in-hospital dialysis was associated with a very low risk of progression to CKD. Most of the patients who progressed to CKD had concurrent medical conditions meriting monitoring of renal function. Therefore, it seems unlikely that regular follow-up of renal function is beneficial in patients who recover to eGFR &gt;60 mL/min/1.73 m2 by 12 months after an episode of AKI

Ferumoxytol-enhanced magnetic resonance angiography for the assessment of potential kidney transplant recipients

Objectives: Traditional contrast-enhanced methods for scanning blood vessels using magnetic resonance imaging (MRI) or CT carry potential risks for patients with advanced kidney disease. Ferumoxytol is a superparamagnetic iron oxide nanoparticle preparation that has potential as an MRI contrast agent in assessing the vasculature. Methods: Twenty patients with advanced kidney disease requiring aorto-iliac vascular imaging as part of pre-operative kidney transplant candidacy assessment underwent ferumoxytol-enhanced magnetic resonance angiography (FeMRA) between December 2015 and August 2016. All scans were performed for clinical indications where standard imaging techniques were deemed potentially harmful or inconclusive. Image quality was evaluated for both arterial and venous compartments. Results: First-pass and steady-state FeMRA using incremental doses of up to 4 mg/kg body weight of ferumoxytol as intravenous contrast agent for vascular enhancement was performed. Good arterial and venous enhancements were achieved, and FeMRA was not limited by calcification in assessing the arterial lumen. The scans were diagnostic and all patients completed their studies without adverse events. Conclusions: Our preliminary experience supports the feasibility and utility of FeMRA for vascular imaging in patients with advanced kidney disease due for transplant listing, which has the advantages of obtaining both arteriography and venography using a single test without nephrotoxicity