4,700 research outputs found

    The SPARC Toroidal Field Model Coil Program

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    Occupational health and safety issues in human-robot collaboration: State of the art and open challenges

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    Human-Robot Collaboration (HRC) refers to the interaction of workers and robots in a shared workspace. Owing to the integration of the industrial automation strengths with the inimitable cognitive capabilities of humans, HRC is paramount to move towards advanced and sustainable production systems. Although the overall safety of collaborative robotics has increased over time, further research efforts are needed to allow humans to operate alongside robots, with awareness and trust. Numerous safety concerns are open, and either new or enhanced technical, procedural and organizational measures have to be investigated to design and implement inherently safe and ergonomic automation solutions, aligning the systems performance and the human safety. Therefore, a bibliometric analysis and a literature review are carried out in the present paper to provide a comprehensive overview of Occupational Health and Safety (OHS) issues in HRC. As a result, the most researched topics and application areas, and the possible future lines of research are identified. Reviewed articles stress the central role played by humans during collaboration, underlining the need to integrate the human factor in the hazard analysis and risk assessment. Human-centered design and cognitive engineering principles also require further investigations to increase the worker acceptance and trust during collaboration. Deepened studies are compulsory in the healthcare sector, to investigate the social and ethical implications of HRC. Whatever the application context is, the implementation of more and more advanced technologies is fundamental to overcome the current HRC safety concerns, designing low-risk HRC systems while ensuring the system productivity

    Sizing the Actuators for a Dragon Fly Prototype

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    In order to improve the design of the actuators of a Dragon Fly prototype, we study the loads applied to the actuators in operation. Both external and inertial forces are taken into account, as well as internal loads, for the purposes of evaluating the influence of the compliance of the arms on that of the "end-effector". We have shown many inadequacies of the arms regarding the stiffness needed to meet the initial design requirements. In order to reduce these inadequacies, a careful structural analysis of the stiffness of the actuators is carried out with a FEM technique, aimed at identifying the design methodology necessary to identify the mechanical elements of the arms to be stiffened. As an example, the design of the actuators is presented, with the aim of proposing an indirect calibration strategy. We have shown that the performances of the Dragon Fly prototype can be improved by developing and including in the control system a suitable module to compensate the incoming errors. By implementing our model in some practical simulations, with a maximum load on the actuators, and internal stresses, we have shown the efficiency of our model by collected experimental data. A FEM analysis is carried out on each actuator to identify the critical elements to be stiffened, and a calibration strategy is used to evaluate and compensate the expected kinematic errors due to gravity and external loads. The obtained results are used to assess the size of the actuators. The sensitivity analysis on the effects of global compliance within the structure enables us to identify and stiffen the critical elements (typically the extremities of the actuators). The worst loading conditions have been evaluated, by considering the internal loads in the critical points of the machine structure results in enabling us the sizing of the actuators. So that the Dragon fly prototype project has been set up, and the first optimal design of the arms has been performed by means of FEM analysis

    Modeling the battery parameters that effect the fault current of a feeding BESS in LV grids

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    The popularity of renewable energy makes the use of battery energy storage systems (BESS) in the grid very attractive. BESS can support the intermittent power output of renewable energy sources. BESS can also provide a support during and after grid failure and even provide black-start capability in case of a blackout. Li-ion batteries are mainly used for these BESS because of their high energy density. In this thesis, the parameters affecting on the fault current of the battery in a BESS are modeled. In most studies around BESS, the inverter has gotten more attention than the battery part. However, the battery part behaves different than a simple DC voltage source. It is evaluated to what extent the behaviour of the battery affects the fault current fed by a BESS. The focus is on the open-circuit voltage (OCV) and internal resistance (Rint) of the battery. The state of charge (SoC), operating temperature, C-rate and state of health (SoH) of the battery affect this voltage and resistance. The behavior of the inverter is also taken into account to get a realistic BESS model. The developed model uses only data available in the manufacturer’s datasheets and information from existing studies. Today, a general fault model already exists for conventional generators, e.g., synchronous generators, but for inverter-based distributed energy resources (IBDER), e.g. BESS, there is not yet a generally accepted model for fault current calculations. There is a great need for simplified fault current models in the industry. These fault models are needed to get the overall dynamic fault response. One possible application is the sizing of overcurrent protection devices. If a BESS feeds in island mode, the available fault current will often be smaller due to the sensitive components that can handle less fault current than robust synchronous or asynchronous machines. These robust generators can provide high short-circuit currents for a short amount of time. The BESS model is incorporated into a simulation software program, here Matlab Simulink, to perform simulation

    Synthesis of multifunctional glyco-pseudodendrimers and glyco-dendrimers and their investigation as anti-Alzheimer agents

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    As the world population is aging, the cases of Alzheimer’s Disease (AD) are increasing. AD is a disorder of the brain which is characterized by the aggregation of amyloid beta (Aβ) plaques. This leads to the death of numerous brain cells thus affecting the cognitive and motor functions of the individual. Till date, no cure for the disease is available. Aβ are peptides with 40/42 amino acid residues but, their exact mechanism(s) of action in AD is under debate. Having different amino acid residues makes them susceptible to form hydrogen bonds. Dendrimers with sugar units are often referred to as glycopolymers and have been shown to have potential anti-amyloidogenic activity. However, they also have drawbacks, the synthesis involves multiple tedious steps, and dendrimers themselves offer only a limited number of functional units. Pseudodendrimers are another class of branched polymers based on hyperbranched polymers. Unlike the dendrimers, they are easy to synthesize with a dense shell of functional units on the surface. One of the main goals in this dissertation is the synthesis and characterization of pseudodendrimers and dendrimers based on 2,2-bis(hydroxymethyl)-propionic acid (bis-MPA), an aliphatic polyester scaffold, as it offers biocompatibility and easy degradability. Furthermore, they are decorated with mannose units on the surface using a ‘click’ reaction forming glyco-pseudodendrimers and glyco-dendrimers. A detailed characterization of their structures and physical properties was undertaken using techniques such as size exclusion chromatography, asymmetric flow field flow fractionation (AF4), and dynamic light scattering. The second main focus of this work has been to investigate the interaction of synthesized glyco-pseudodendrimers and glyco-dendrimers with Aβ 40 peptides. For this task, five different concentrations of the synthesized glycopolymers were tested with Aβ 40 using the Thioflavin T assay. The results of the synthesized polymers which produced the best results of showing maximum anti-aggregation behavior against Aβ 40 were confirmed with circular dichroism spectroscopy. AF4 was also used to investigate Aβ 40-glycopolymer aggregates, which has never been done before and constitutes the highlight of this dissertation. Atomic force microscopy was used to image Aβ 40-glycopseudodenrimer aggregates. A basic but important step in the development of drug delivery platforms is to evaluate the toxicity of the drugs synthesized. In this work, preliminary studies of the cytotoxicity of glyco-pseudodendrimers were performed in two different cell lines. Thus, this study comprises a preliminary investigation of the anti-amyloidogenic activity of glyco-pseudodendrimers synthesized on an aliphatic polyester backbone.:Abstract List of Tables List of Figures Abbreviations 1 Introduction 1.1 Objectives of the work 1.2 Thesis overview 2 Fundamentals and Literature 2.1 Alzheimer’s Disease and its impact 2.1.1 Neurological diagnosis of AD 2.1.2 Histopathology of AD 2.1.3 Amyloid precursor protein (APP) and its role in AD 2.2. Amyloid Beta (Aβ) peptide 2.2.1 Aβ peptide 2.2.2. Location and function 2.2.3 Amyloid hypothesis 2.2.4 The mechanism of Aβ aggregation 2.2.5 Amyloid fibrils 2.2.6 Toxicity of Aβ 2.3 Research methods to study Aβ aggregates 2.3.1 Models to study the mode of action of aggregates 2.3.2 Endogenous Aβ aggregates and synthetic aggregates 2.3.3 Strategies to alter aggregation of amyloids 2.4 Treatment and therapeutics 2.4.1 Current therapeutics 2.4.2 Current therapeutic research 2.4.2.1 Reduction of Aβ production 2.4.2.2 Reduction of Aβ plaque accumulation 2.4.2.2.1 Anti-amyloid aggregation agents 2.4.2.2.2 Metals 2.4.2.2.3 Immunotherapy 2.4.2.2.4 Dendrimers as potential anti-amyloidogenic agent 2.6 Dendrimers 2.6.1 Definition 2.6.2 Structure Table of Contents 2.6.3 Synthesis 2.6.4 Properties 2.7 Pseudodendrimers - a sub-class of hyperbranched polymer 2.7.1 Definition 2.7.2 Structure 2.7.3 Synthesis 3 Analytical Techniques 3.1 Size Exclusion Chromatography Coupled to Light Scattering (SEC-MALS) 3.2 Asymmetric Flow Field Flow Fractionation (AF4) 3.3 Dynamic Light Scattering 3.4 Molecular Dynamics Simulation 3.5 Nuclear Magnetic Resonance Spectroscopy 3.6 Thioflavin T fluorescence 3.6.1 Kinetic analysis 3.7 Circular Dichroism Spectroscopy 3.8 Atomic Force Microscopy 3.9 Cytotoxic assay 3.9.1 MTT assay 3.9.2 Determining the level of reactive oxygen species 3.9.3 Changes in mitochondrial transmembrane potential 3.9.4 Flow cytometric detection of phosphatidyl serine exposure 4 Experimental Details and Methodology 4.1 Details of chemicals/components used 4.1.1 Other materials 4.1.2 Peptide preparation 4.1.3 Buffer preparation 4.1.4 Fibril growth conditions 4.2 Synthesis and characterization of polymers 4.2.1 Synthesis and characterization of pseudodendrimers and dendrimers 4.2.1.1 Synthesis of hyperbranched polymer (1) 4.2.1.2 Synthesis of protected monomer 4.2.1.2.1 bis-MPA acetonide (2) 4.2.1.2.2 bis-MPA-acetonide anhydride (3) 4.2.1.3 Synthesis of protected pseudodendrimers (4, 6 and 8) and protected dendrimers (10, 12, and 14) 4.2.1.4 Deprotection of pseudodendrimers (5,7, and 9) and dendrimers (11,13 and 15) 4.2.2 Synthesis of glyco-pseudodendrimers and glyco-dendrimers 4.2.2.1 Pentynoic anhydride (16) 4.2.2.2 Synthesis of pentinate modified pseudodendrimers (17, 18 and 19) and dendrimers (20, 21 and 22) 4.2.2.3 3-Azido-1-propanol (23) 4.2.2.4 Mannose propyl azide tetraacetate (24) Table of Contents 4.2.2.5 Mannosepropylazide (25) 4.2.2.6 Glyco-pseudodendrimers (Gl-P) (26, 27 and 28) and glyco- dendrimers (Gl-D) (29, 30 and 31) 4.3 Analytical techniques and their general details 4.3.1 SEC-MALS - Instrumentation, software and analysis 4.3.2 AF4 - Instrumentation, software and analysis 4.3.2.1 Sample preparation 4.3.2.2 Method development for analysis of Gl-P and Gl-D 4.3.2.3 Method development for analysis of Aβ 40 and its interaction with Gl-P and Gl-D 4.3.3 Batch DLS - Instrumentation, software and analysis 4.3.3.1 Sample preparation 4.3.4 Theoretical calculations and molecular dynamics simulations 4.3.4.1 Ab-initio calculations 4.3.4.2 Modelling of the polymer structures 4.3.4.2.1 Pseudodendrimers 4.3.4.2.2 Dendrimers 4.3.4.2.3 Modification of the polymers with special end groups 4.3.4.2.4 Preparing of the THF solvent box 4.3.4.2.5 Solvation of the polymer structures 4.3.4.3 Molecular dynamics simulations 4.3.4.3.1 Evaluation of the simulation trajectories 4.4 Investigation of interaction of Gl-P and Gl-D with amyloid beta (Aβ 40) 4.4.1 ThT Assay - Instrumentation and software 4.4.1.1 Sample preparation 4.4.1.2 Kinetics based on ThT assay- software and data analysis 4.4.2 CD spectroscopy - Instrumentation and software 4.4.2.1 Sample preparation 4.4.3 AFM - Instrumentation and software 4.4.3.1 Substrate and sample preparation 4.4.3.2 Height determination and counting procedures 4.4.3.3 Topography and diameter 4.5 Cytotoxicity 4.5.1 Zeta potential 4.5.2 Cell culturing 4.5.3 Sample preparation 4.5.4 MTT assay 4.5.5 Changes in mitochondrial transmembrane potential (JC-1 method) 4.5.6 Flow cytometric detection of phosphatidyl serine exposure (Annexin V and PI method) 5 Results and Discussion 5.1 Synthesis and characterization of glyco-pseudodendrimers and glyco- dendrimers 5.1.1 Synthesis and characterization of hyperbranched polyester Table of Contents 5.1.2 Synthesis and characterization of pseudodendrimers P-G1-OH, P-G2-OH and P-G3-OH 5.1.3 Synthesis and characterization of dendrimers D-G4-OH, D-G5-OH and D-G6-OH 5.1.4 Synthesis and characterization of Gl-P and Gl-D 5.1.4.1 Molecular size determination of Gl-P and Gl-D using SEC 5.1.4.2 Particle size determination using batch DLS 5.1.4.3 Apparent densities 5.1.4.4 Molecular size determination of Gl-P and Gl-D using AF4 ..... 5.1.5 Molecular dynamics simulation 5.2 Investigation of interaction of Gl-P and Gl-D with amyloid beta (Aβ 40) ...... 5.2.1 ThT Assay 5.2.1.1 Kinetics based on ThT assay 5.2.2 CD spectroscopy 5.2.3 Time dependent AF4 5.3.2.1 Separation of Aβ 40 by AF4 5.3.2.2 Aβ 40 amyloid aggregation in the presence of Gl-P and Gl-D 5.2.4 AFM 5.2.4.1 Height 5.2.4.2 Topography and diameter 5.2.4.3 Length 5.2.4.4 Morphology 5.2.5 Cytotoxicity 5.2.5.1 MTT assay 5.2.5.2 Changes in mitochondrial transmembrane potential 5.2.5.3 Flow cytometric detection of phosphatidyl serine exposure 6 Conclusions and Outlook 7 Bibliography Appendix Acknowledgement

    Robot-Enabled Construction Assembly with Automated Sequence Planning based on ChatGPT: RoboGPT

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    Robot-based assembly in construction has emerged as a promising solution to address numerous challenges such as increasing costs, labor shortages, and the demand for safe and efficient construction processes. One of the main obstacles in realizing the full potential of these robotic systems is the need for effective and efficient sequence planning for construction tasks. Current approaches, including mathematical and heuristic techniques or machine learning methods, face limitations in their adaptability and scalability to dynamic construction environments. To expand the ability of the current robot system in sequential understanding, this paper introduces RoboGPT, a novel system that leverages the advanced reasoning capabilities of ChatGPT, a large language model, for automated sequence planning in robot-based assembly applied to construction tasks. The proposed system adapts ChatGPT for construction sequence planning and demonstrate its feasibility and effectiveness through experimental evaluation including Two case studies and 80 trials about real construction tasks. The results show that RoboGPT-driven robots can handle complex construction operations and adapt to changes on the fly. This paper contributes to the ongoing efforts to enhance the capabilities and performance of robot-based assembly systems in the construction industry, and it paves the way for further integration of large language model technologies in the field of construction robotics.Comment: 14 pages, 20 figures, submitted to IEEE Acces

    Leveraging elasticity theory to calculate cell forces: From analytical insights to machine learning

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    Living cells possess capabilities to detect and respond to mechanical features of their surroundings. In traction force microscopy, the traction of cells on an elastic substrate is made visible by observing substrate deformation as measured by the movement of embedded marker beads. Describing the substrates by means of elasticity theory, we can calculate the adhesive forces, improving our understanding of cellular function and behavior. In this dissertation, I combine analytical solutions with numerical methods and machine learning techniques to improve traction prediction in a range of experimental applications. I describe how to include the normal traction component in regularization-based Fourier approaches, which I apply to experimental data. I compare the dominant strategies for traction reconstruction, the direct method and inverse, regularization-based approaches and find, that the latter are more precise while the former is more stress resilient to noise. I find that a point-force based reconstruction can be used to study the force balance evolution in response to microneedle pulling showing a transition from a dipolar into a monopolar force arrangement. Finally, I show how a conditional invertible neural network not only reconstructs adhesive areas more localized, but also reveals spatial correlations and variations in reliability of traction reconstructions

    Acoustic Propagation Variation with Temperature Profile in Water Filled Steel Pipes at Pressure

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    Conventional pressure leak testing of buried pipelines compares measurements of pressure with pipe wall temperature. An alternative proposed method uses acoustic velocity measurements to replace pipe wall temperature measurements. Early experiments using this method identified anomalous results of rising acoustic velocities thought to be caused by air solution. This research investigated the anomalous acoustic velocity measurements by evaluation of acoustic velocity variation with pressure, temperature and air solution. Quiescent air solution rate experiments were carried out in water filled pipes. Computer modelling of the air bubble shape variation with pipe diameter was found to agree with bubble and drop experiments over the pipe diameter range from 100 mm to 1000 mm. Bubbles were found to maintain constant width over a large volume range confirmed by experiments and modelling

    Evaluation Methodologies in Software Protection Research

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    Man-at-the-end (MATE) attackers have full control over the system on which the attacked software runs, and try to break the confidentiality or integrity of assets embedded in the software. Both companies and malware authors want to prevent such attacks. This has driven an arms race between attackers and defenders, resulting in a plethora of different protection and analysis methods. However, it remains difficult to measure the strength of protections because MATE attackers can reach their goals in many different ways and a universally accepted evaluation methodology does not exist. This survey systematically reviews the evaluation methodologies of papers on obfuscation, a major class of protections against MATE attacks. For 572 papers, we collected 113 aspects of their evaluation methodologies, ranging from sample set types and sizes, over sample treatment, to performed measurements. We provide detailed insights into how the academic state of the art evaluates both the protections and analyses thereon. In summary, there is a clear need for better evaluation methodologies. We identify nine challenges for software protection evaluations, which represent threats to the validity, reproducibility, and interpretation of research results in the context of MATE attacks

    Systemic Circular Economy Solutions for Fiber Reinforced Composites

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    This open access book provides an overview of the work undertaken within the FiberEUse project, which developed solutions enhancing the profitability of composite recycling and reuse in value-added products, with a cross-sectorial approach. Glass and carbon fiber reinforced polymers, or composites, are increasingly used as structural materials in many manufacturing sectors like transport, constructions and energy due to their better lightweight and corrosion resistance compared to metals. However, composite recycling is still a challenge since no significant added value in the recycling and reprocessing of composites is demonstrated. FiberEUse developed innovative solutions and business models towards sustainable Circular Economy solutions for post-use composite-made products. Three strategies are presented, namely mechanical recycling of short fibers, thermal recycling of long fibers and modular car parts design for sustainable disassembly and remanufacturing. The validation of the FiberEUse approach within eight industrial demonstrators shows the potentials towards new Circular Economy value-chains for composite materials
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