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An Integrated Active Measurement Programming Environment
Get PDFActive Internet measurement is not a zero-risk activity, and access to Internet measurement vantage points typically requires navigating trust relationships among actors involved in deploying, operating, and using the infrastructure. Operators of vantage points (VPs) must balance VP capability against who gets access: the more capable a vantage point, the riskier it is to allow access. We propose an integrated active measurement programming environment that: (1) allows a platform operator to specify the measurements that a user can run, which allows the platform operator to communicate to the VP’s host what their vantage point will do, and (2) provides users with reference implementations of measurement functions that act as building blocks to more complex measurements. We first review active measurement infrastructures and how technical and usability goals have evolved over the years. We prototype and deploy an integrated active measurement programming environment on an existing measurement infrastructure, and illustrate its potential with several case studies.</p
Guidance to solid state electrochemical impedance spectroscopy
Get PDFElectrochemical Impedance Spectroscopy (EIS) is a much valued research tool for studying electrochemical cells, systems and devises. With this non-invasive technique mass and charge transport and storage is studied by measuring the response to a sinusoidal perturbation signal (voltage or current) over a wide frequency range. The frequency dependent relation between perturbation and response can be presented as a complex valued impedance, admittance, dielectric, etc. Acquisition of the spectra is relatively easy with modern automated Frequency Response Analysis (FRA) systems, but the interpretation is often complicated. Lack of experience can lead to misinterpretation and inadequate presentation of results. Data validation with a Kramers-Kronig consistency check is an essential starting point for the data analysis process. The Complex Nonlinear Least Squares (CNLS) analysis method, based on an Equivalent Circuit Model (ECM) or a special transfer function is still the most used procedure for data interpretation. Inversion of impedance data to a Distribution Function of Relaxation Times (DFRT) is gaining significant attention. Sufficient knowledge of, and experience with these techniques is required for arriving at a trustworthy result. Unfortunately, many manuscripts lack a thorough evaluation of the obtained results. In several cases these problems pass uncorrected the peer review system. This contribution provides a brief overview of mistakes quite often made in EIS analysis. It tries to provide guidance for the inexperienced scientists. Simultaneously, to support prospective reviewers of EIS related manuscripts, a checklist is presented with common EIS analysis and interpretation errors.</p
Changing Health Goals with Personal Informatics
Get PDFPeople's health goals change as their contexts, needs, and values evolve. Personal informatics (PI) literature recognizes the importance of supporting goal change; however, little is known about how these tools can best support the changes people go through with their goals. To understand how PI are currently involved in goal change, we conducted a survey (N=80) and interview (N=10) study with people who had recently changed their health goals. Overall, we found that PI gave limited support to people during goal changes. Changes were driven by four actors (i.e., who and what influences the goal change): internal motivations, contexts, PI, and social surroundings. We further highlight five factors related to goal change (i.e., the ways in which the actors affect goal change): challenge, self-efficacy, changing priorities, learning, and enjoyment. We discuss how PI could better support people in goal change by considering different implementations and interactions of actors and factors.</p
Automated tuning and characterization of a single-electron transistor charge sensor
Get PDFWe present an automated protocol for tuning single-electron transistors (SETs) or single-hole transistors (SHTs) to operate as precise charge sensors. Using minimal device-specific information, the protocol performs measurements to enable the selection and ranking of high-sensitivity operating points. It also characterizes key device parameters, such as dot radius and gate lever arms, through acquisition and analysis of Coulomb diamonds. Demonstration on an accumulation-mode silicon SET at 1.5 K highlights its potential in the 1-2 K range for "hot" spin qubits in scalable quantum computing systems. This approach significantly reduces the tuning time compared to manual methods, with future improvements aimed at faster runtimes and dynamic feedback for robustness to charge fluctuations
PV on façades:A financial, technical and environmental assessment
Get PDFAs roof space has become increasingly occupied, facades serve as an alternative for deploying PV, often in the form of Building-Integrated Photovoltaics (BIPV). In this study, a comprehensive analysis over multiple years of the value of integrating PV on facades with different configurations is provided. The comparison comprises financial, technical and environmental metrics and spans the Dutch and German electricity sector. As expected, due to the much higher yield of optimally oriented PV, it generates higher revenues and reduce more CO2 emissions than facade PV. Over the course of five years of this study, south, east, and west facades reduce 1725, 1492, 1335 kg of CO2 emission per kWp of PV installation, while this is 2434 for the optimally oriented PV. However, analyzing the value factor of PV-generated electricity shows east and west facade are increasingly generating more economic value compared to optimally-oriented PV: the value factor or capture rate of optimally-oriented PV decreased to 0.73 in 2023, whereas the value factor for east facade and west facade remained higher (0.87 and 0.84, respectively). From a technical viewpoint, facade PV results in much higher self-consumption ratios 42% for east facade, 46% for west facade, compared to only 30% for optimally-oriented (all 1 kWp installed per 1 MWh demand). Concluding, facade PV, while having a much lower yield than optimally oriented PV, does hold some significant advantages over optimally-oriented PV – mainly in technical terms and in economic terms. Therefore, facade PV can be seen as a very promising option for the PV sector in general, and the BIPV sector specifically – especially in a more and more congested electricity grid.</p
Mixed reality meets circular economy:The case of battery lifecycle management
Get PDFDespite recent digitalization efforts across European industries, research gaps persist in applying mixed reality (MR) within circular economy (CE) frameworks. Specifically, there is limited exploration of data integration, an unclear value proposition for digital tools, and minimal engagement from business perspectives. Despite growing interest, a structured framework mapping MR applications to CE processes remains underexplored. This paper addresses this gap by mapping MR modules to CE practices across lifecycle phases, illustrating specific use cases in design, manufacturing, use, and end-of-life stages. The paper also exploits MR applications for sustainable battery manufacturing, using real-time data to monitor and guide disassembly and recycling processes. This work contributes to advancing sustainable practices and facilitating the transition to circular business models by demonstrating the role of MR in promoting efficient resource use, disassembly, and recycling within a closed-loop system.</p
Spaceborne hyperspectral sensing for geoscience mapping:Comparisons and examples for geological applications
Get PDFGraphene-Coated Paraffin Composites:Numerical Investigation of Effective Thermal Properties
No full textThis thesis presents a numerical study of graphene-coated paraffin composites for thermal energy storage. Using OpenFOAM and periodic representative volume elements, it examines how microscale features like sphere size, coating thickness, and volume fraction influence heat conduction and thermal response. The work defines numerical resolution criteria, introduces thermal reaction time, and explores the thermodynamic limit of conductivity in multisphere systems. At high volume fractions, early signs of percolation are observed. The results show that graphene coatings enhance performance when geometry and resolution are properly controlled, providing a numerical foundation for the design of efficient and responsive composites
Perceiving and Countering Marine Biofouling:Structure, Forces, and Processes at Surfaces in Sea Water Across the Length Scales
Get PDFIn marine industries, severe economic losses are caused by accumulating organisms on surfaces in biofouling processes. Establishing a universal and nontoxic protocol to eliminate biofouling has been a notoriously difficult task due to the complexity of the marine organisms’ interactions with surfaces and the chemical, mechanical, and morphological diversity of the surfaces involved. The tremendous variety of environmental parameters in marine environments further complicates this field. For efficient surface engineering to combat fouling, secretion, chemical structure, and properties of biobased adhesives and adhesion mechanisms must be understood. Advanced characterization techniques, like Atomic Force Microscopy (AFM), now allow one to study the three parameters determining surface adhesion and, eventually, fouling, i.e., morphology, chemistry, and surface mechanical modulus. By AFM, characterization can now be performed across length scales from nanometers to hundreds of micrometers. This review provides an up-to-date account of the most promising AFM-based approaches for imaging and characterizing natural adhesives provided by marine organisms. We summarize the current understanding of the molecular basis and the related relevant processes of marine fouling. We focus on applications of AFM “beyond imaging”, i.e., to study interactions between adhesives and the surfaces involved. Additionally, we discuss the performance enhancement of polymer antifouling coatings using information derived from AFM. Knowledge and control of marine adhesion can be applied to prevent marine fouling, as well as to design bioadhesives to enhance potential medical applications. We present some milestone results and conclude with an outlook discussing novel possibilities for designing antifouling coatings and medical bioadhesives.</p
Rubber-like and Antifouling Poly(trimethylene carbonate-ethylphosphonate) Copolymers with Tunable Hydrolysis
Get PDFControlling the degradation and cell interaction of polymer materials is vital for numerous applications. Transitioning from enzymatic to nonenzymatic hydrolysis offers precise control over degradation processes. In this study, we synthesized high molar mass poly(trimethylene carbonate) (PTMC)-polyphosphonate copolymers to achieve distinctive antifouling and controlled degradation properties. 2-Ethyl-2-oxo-1,3,2-dioxaphospholane (EtPPn) is copolymerized with trimethylene carbonate (TMC) to random P(TMC-co-EtPPn) copolymers through ring-opening copolymerization, utilizing Sn(Oct)2 as the catalyst. Copolymers with molar masses reaching up to Mn = 218 kg/mol and molar mass dispersities of D̵ < 1.9 are obtained. To maintain hydrophobicity, 10 and 20 mol % of hydrophilic phosphonate units are incorporated into PTMC-copolymers. While copolymers with 10 mol % EtPPn display mechanical properties akin to the homopolymer PTMC, a deviation in elongation at break and yield strength results when 20 mol % EtPPN is incorporated. PTMC-PPE copolymers demonstrate antifouling behavior, i.e., cell repulsion for human mesenchymal stem cells (hMSCs) and inhibited enzymatic degradation by lipase in contrast to PTMC-homopolymers. Conversely, P(TMC-co-EtPPn) undergo abiotic hydrolytic degradation with hydrolysis rates increasing with increasing phosphonate contents. In conclusion, copolymerization with EtPPn enables the switch from enzymatic PTMC degradation to adjustable hydrolytic degradation, offering controlled stabilities of such copolymers in the desired applications.</p