137 research outputs found
Corrigendum:Deep Learning for Whole Slide Image Analysis: An Overview (Front. Med. (2019), 6, (264), 10.3389/fmed.2019.00264)
No full textEqual contribution was incorrectly attributed to the authors. Instead, the statement “These authors have contributed equally to this work” should be removed.In the published article, Peter D Caie was incorrectly listed as the corresponding author. Instead, Neofytos Dimitriou should be the corresponding author. The corresponding author’s email address should read [email protected]. The authors apologize for these errors and state that these do not change the scientific conclusions of the article in any way. The original article has been updated.</p
A Web Application for the Photon Strength Function Database
No full textA specialized web application has been developed to manage, query, and visualize photon strength function (PSF) data, compiled as a part of an IAEA Coordinated Research Project. This application significantly advances accessibility and interaction with the data over existing platforms, improving upon the capabilities of the prior resource. Central to this application is the database structure, crucial for efficient data management and retrieval. Built using the Django framework, the Web application’s user interface presents queried data and search results in an accessible format. t provides details on basic nuclear properties, including the atomic number (Z), mass number (A), multipolarity, energy range, and the experimental methods used. In addition, the application offers functionalities for searching and sorting data by author names or publication years, facilitating refined navigation through the extensive PSF data repository. A notable feature is the dynamic data visualization tool that utilizes Plotly to create interactive graphs. The platform also features a comprehensive data processing pipeline that ensures data integrity and accessibility
Improving jack-up capabilities
No full textSo far jack-ups have successfully operated in depths of 80 to 100 m and some are capable of operating in water depths of up to 150 m. In order to circumvent the depth limitation, it was suggested by Heerema Marine Contractors (HMC) that a base could be designed with the ability to support a jack-up rig, thereby increasing its operational depth capability. Such a support structure for jack-ups (named SSfJ) that can possibly be mobilized and demobilized by an HMC vessel would allow HMC to offer its services to another part of the Oil and Gas industry, the Drilling and Workover sector. A first investigation into the feasibility of this idea is carried out in this thesis. The focus of the thesis is placed on determining whether a 3-legged North Sea drilling jack-up can potentially survive on a SSfJ and on the calculation of the structural characteristics of the SSfJ that are required for enabling a jack-up to do so. The first step in this research was to verify if there is a commercial driver for the SSfJ. Therefore a market research took place which focused on the North Sea offshore drilling industry and showed that there is a need for high spec and deep water jack-ups and a great need for reduction in drilling costs. The driver was therefore clear, namely that there is a need to design a SSfJ that will enable jack-ups to operate in deeper water without much increase in costs. Then, based on market information it was decided to consider a SSfJ that would add 30m of water depth capability to the GustoMSC CJ 70 jack-up type. The main (technical) part of the thesis focused on identifying how the jack-up integrity will be influenced when it is placed on the SSfJ and what structural characteristics the SSfJ should have in order to enable a jack-up to survive on it through the harshest North Sea environmental conditions. The influence of the use of the SSfJ was assessed via reasonable assumptions that were then verified with analysis in the software SACS. The required structural characteristics of the SSfJ were identified as the SSfJ stiffness and rotational fixity at the SSfJ – jack-up interface. Recommended values for these characteristics were identified via an iterative procedure that includes a simplified dynamic analysis method that uses a Dynamic Amplification Factor. The results were then verified with a more accurate method that employs the time domain simulations in SACS. The outcome of the research is that the jack-up integrity is not influenced negatively by the use of SSfJ and that if the SSfJ has the recommended structural characteristics then the jack-up can survive the harshest environmental conditions in the North Sea.Bottom Founded StructuresOffshore and DredgingMechanical, Maritime and Materials Engineerin
Skeletal muscle mitochondrial dysfunction mediated by Pseudomonas aeruginosa quorum-sensing transcription factor MvfR: reversing effects with anti-MvfR and mitochondrial-targeted compounds
No full textABSTRACT Sepsis and chronic infections with Pseudomonas aeruginosa, a leading “ESKAPE” bacterial pathogen, are associated with increased morbidity and mortality and skeletal muscle atrophy. The actions of this pathogen on skeletal muscle remain poorly understood. In skeletal muscle, mitochondria serve as a crucial energy source, which may be perturbed by infection. Here, using the well-established backburn and infection model of murine P. aeruginosa infection, we deciphered the systemic impact of the quorum-sensing transcription factor MvfR (multiple virulence factor regulator) by interrogating, 5 days post-infection, its effect on mitochondrial-related functions in the gastrocnemius skeletal muscle and the outcome of the pharmacological inhibition of MvfR function and that of the mitochondrial-targeted peptide, Szeto-Schiller 31 (SS-31). Our findings show that the MvfR perturbs adenosine triphosphate generation, oxidative phosphorylation, and antioxidant response, elevates the production of reactive oxygen species, and promotes oxidative damage of mitochondrial DNA in the gastrocnemius muscle of infected mice. These impairments in mitochondrial-related functions were corroborated by the alteration of key mitochondrial proteins involved in electron transport, mitochondrial biogenesis, dynamics and quality control, and mitochondrial uncoupling. Pharmacological inhibition of MvfR using the potent anti-MvfR lead, D88, we developed, or the mitochondrial-targeted peptide SS-31 rescued the MvfR-mediated alterations observed in mice infected with the wild-type strain PA14. Our study provides insights into the actions of MvfR in orchestrating mitochondrial dysfunction in the skeletal murine muscle, and it presents novel therapeutic approaches for optimizing clinical outcomes in affected patients.IMPORTANCESkeletal muscle, pivotal for many functions in the human body, including breathing and protecting internal organs, contains abundant mitochondria essential for maintaining cellular homeostasis during infection. The effect of Pseudomonas aeruginosa (PA) infections on skeletal muscle remains poorly understood. Our study delves into the role of a central quorum-sensing transcription factor, multiple virulence factor regulator (MvfR), that controls the expression of multiple acute and chronic virulence functions that contribute to the pathogenicity of PA. The significance of our study lies in the role of MvfR in the metabolic perturbances linked to mitochondrial functions in skeletal muscle and the effectiveness of the novel MvfR inhibitor and the mitochondrial-targeted peptide SS-31 in alleviating the mitochondrial disturbances caused by PA in skeletal muscle. Inhibiting MvfR or interfering with its effects can be a potential therapeutic strategy to curb PA virulence
Enhanced Simulation of Guided Waves and Damage Localization in Composite Strips Using the Multiresolution Finite Wavelet Domain Method
No full textA multiresolution finite wavelet domain method, that utilizes Daubechies wavelet and scaling functions for the hierarchical approximation of state variables, is presented. The multiresolution approximation yields a hierarchical set of equations of motion involving the coarse component of generalized displacements, while additional equations of finer components are subsequently added. A coarse solution is first calculated, and finer solutions can be sequentially superimposed on the coarse solution until convergence to the final solution is achieved. Moreover, it is shown that each resolution can model specific bandwidths of wavenumbers, thus providing a unique capability to separate coexisting wave modes and detect converted and reflected waves in the presence of damage. Two wavelet-based beam elements are explored, the first encompasses the Timoshenko shear beam theory and the second a high-order layerwise laminate theory for the accurate prediction of both symmetric and antisymmetric guided waves. Numerical results illustrate the inherent property of the method to a priori localize and isolate coexisting guided wave modes and their conversions, induced by different material regions and weak or debonded layer interfaces, thus demonstrating the method’s intrinsic capabilities towards the design of wave-based SHM systems.Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Structural Integrity & Composite
Analysis and Simulation of an Anode Supported Solid Oxide Fuel Cell Single Channel for Operation with Biosyngas and Methane
No full textA three-dimensional thermo-fluid model coupled with electrochemical reaction for an anode-supported planar SOFC has been developed to investigate the internal processes and temperature distribution within a single cell unit for the design proposed by the Energy research Center of the Netherlands (ECN) in cooperation with TU Delft. The SOFC developed is for operation with natural gas. In this work, operation with biosyngas is evaluated. The electrochemical reactions, heat and mass transfer phenomena between the solid and gas phases have all been included in the cell model. The object is to investigate the complete cell using the models developed and make comparisons for the cell performance when fed with hydrogen, methane and different biosyngas compositions, come up with suggestions for efficient and ideal SOFC operation conditions when fed with different fuels and investigate safety issues under different working conditions. In order to clarify the goals of this work, the following questions have to be answered \u95 Is operation with biosyngas safe for the SOFC (Ni oxidation, carbon deposition)? \u95 Is operation with methane safe for the SOFC (Ni oxidation, carbon deposition)? \u95 What is the impact of different fuel compositions on SOFC performance? \u95 What is the impact of the steam reforming reaction of methane on the SOFC performance for operation with biosyngas and methane? \u95 What constructive suggestions can be made for further development of SOFCs?MSc Sustainable Energy TechnologyProcess and EnergyMechanical, Maritime and Materials Engineerin
Planning for the regeneration of listed buildings for vulnerable social groups using Zero-Energy and Circular Principles: The case of the refugee settlements of Alexandra’s Avenue in Athens, Greece
No full textThe present thesis discusses social, cultural, economic and environmental aspects of problems related to heritage building depreciation, homelessness and lack of affordable housing, with a focus on the more vulnerable social groups. It additionally argues the mitigation of the impact of the cities and the building sector on climate crisis. The aim of the thesis is to find a sustainable, in terms of longevity and feasibility, connection between the unexploited building stock and the shelter-less people, for the benefit of the users, the society and the environment alike, through zero-energy design and circular adaptation. The study analyzes the possible approach of renovation and adaptive reuse of the existing, untapped, residential buildings in order to meet the current climate regulations and future occupants’ needs. A literature review examines three main domains separately: zero-energy design, circularity and collective housing. A case study analysis of alternative collective housing models in particular monitors the porosity of this plan and its ability to be combined with zero-energy and circular principles. This research offers the opportunity to recognize possible methodologies that can then be applied on a specific case study. Research is consolidated in the case of the refugee settlement complex of Alexandra’s Avenue (1933-36), in the city of Athens, and seeks to propose a number of recommendations for its renovation, energy upgrade, redevelopment and reuse. The fact that the research refers to listed buildings, constitutes the biggest limitation, in terms of design decisions. The case study it-self, clearly depicts the afore-mentioned issues in the Athenian context, and alongside includes building, social, historic and other characteristics that compose an ideal example for an energy efficient, user-oriented, adaptive reuse.A step-by-step approach is adopted in order to develop (re)design methodologies for the energy transition and circular adaptation of the case study. In addition, a possible network of interactions between the involved stakeholders is proposed so as to create a holistic and functional business model. Ultimately, the thesis proposes an inclusive and integrated framework for the renovation of the existing, old, heritage, building stock, driven by zero-energy and circular principles, for the less-favored, towards a new typology of social and collective housing. The development of this framework is based on facts and data that can make it potentially applicable to similar cases elsewhere. Further research on the topic would help facilitate the transition to integrated frameworks of renovation processes.Architecture, Urbanism and Building Sciences | Building Technolog
Evaluation on the Effect of Buoyancy on the flow, heat transfer and performance of a Printed Circuit Heat Exchanger A Numerical Study
No full textOne of the biggest threats that humanity is currently facing is the climate change. The amount of greenhouse gases emissions and specifically the amount of CO2 in the atmosphere has increased and is projected to increase even more in the next years. One possible solution is the use of supercritical CO2 as an alternative working fluid in power cycles (e.g., Rankine and Brayton cycle). Supercritical fluids operate at pressures and temperature higher than their corresponding critical pressure and temperature value. They behave as a single-phase substances with variable thermophysical properties. CO2 at supercritical conditions is denser than supercritical water and steam which can affect the efficiency and the design of multiple mechanical components. printed circuit heat exchangers due to their unique design are suitable for supercritical application. They are compact heat exchangers which can operate at high pressures and temperatures and they can achieve high effectiveness. Because of the rapid variation of the thermophysical properties, heat transfer and flow characteristics in supercritical conditions are affected. Three typical heat transfer modes can occur: 1) Normal Heat Transfer, 2) Deteriorated Heat Transfer and 3) Enhanced Heat Transfer. Furthermore, induced forces due to the density difference also known as buoyancy effects are observed in these conditions and can affect both the flow, the heat transfer of the fluid and thus the performance of the heat exchanger. The main focus of this study is the induced buoyancy effects inside a printed circuit heat exchanger at laminar flow. Initially, a printed circuit heat exchanger is designed based on the literature. Using this heat exchanger geometry two sets of simulations are conducted in OpenFOAM. In the first set of simulations the Reynolds number and the flow thermal capacity are kept constant while the Grashof number is kept nearly constant in order to determine the dependence of Grashof number on the buoyancy effects. In the second set of simulations the Reynolds number, the flow thermal capacity and temperature difference are kept constant to evaluate the performance of the heat exchanger under real working conditions. Three geometries are under investigation (0.015/ 0.03/ 0.06 m) in three different orientations. 1) Vertical Upwards (Assisted Buoyancy), 2) Vertical Downwards (Opposed Buoyancy) and 3) Horizontal.In the assisted buoyancy cases the induced buoyancy effects produce an M-shape velocity profile due to the acceleration of the flow near the walls and the deceleration of the flow in the centre of the channel. In this orientation the heat transfer coefficient and the Nusselt number increase and enhanced heat transfer is observed. On the other hand, in the opposed buoyancy cases the velocity near the walls decelerates and accelerates in the centre of the channel resulting to the formation of a Bell-shape velocity profile. Both the heat transfer coefficient and the Nusselt number in this orientation decreases and therefore deteriorated heat transfer is observed. It is also shown that in the opposed buoyancy cases the intense buoyancy effects can produce instabilities of the flow and recirculation zones inside the heat exchanger. Instead of the expected deteriorated heat transfer, the produced instabilities result in enhancement of heat transfer. In the horizontal cases, depending on the conditions, heating or cooling, the maximum streamwise velocity is shifted at the bottom surface (Heating conditions) and at the top surface (Cooling conditions). The formation of the secondary flow inside the horizontal heat exchangers produces an average increase of the heat transfer coefficient and the Nusselt number, thus enhancement of heat transfer. The performance of the printed circuit heat exchanger in the three orientations is also evaluated. It is shown that buoyancy effects can directly affect the effectiveness and the performance of the heat exchanger. In the cases where enhancement of heat transfer is observed (Assisted Buoyancy and Horizontal) the heat exchanger’s effectiveness increases. For the Opposed Buoyancy cases decrease of the effectiveness is observed due to the deterioration of heat transfer inside the heat exchanger. Important parameters when investigating buoyancy effects inside the heat exchanger are the diameter of the geometry (Directly proportional to the magnitude of the buoyancy effects) and the Grashof number (Differentiates between all the cases and can be used as an indication of the importance of the buoyancy effects). In all the aforementioned cases the overall heat transfer coefficient is affected which has a direct impact on the design (Length) and the cost of the heat exchanger. Mechanical Engineerin
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