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A Graded Modal Dependent Type Theory with a Universe and Erasure, Formalized
Get PDFWe present a graded modal type theory, a dependent type theory with grades that can be used to enforce various properties of the code. The theory has II-types, weak and strong Σ-types, natural numbers, an empty type, and a universe, and we also extend the theory with a unit type and graded Σ-types. The theory is parameterized by a modality, a kind of partially ordered semiring, whose elements (grades) are used to track the usage of variables in terms and types. Different modalities are possible. We focus mainly on quantitative properties, in particular erasure: with the erasure modality one can mark function arguments as erasable. The theory is fully formalized in Agda. The formalization, which uses a syntactic Kripke logical relation at its core and is based on earlier work, establishes major meta-theoretic properties such as subject reduction, consistency, normalization, and decidability of definitional equality. We also prove a substitution theorem for grade assignment, and preservation of grades under reduction. Furthermore we study an extraction function that translates terms to an untyped λ-calculus and removes erasable content, in particular function arguments with the "erasable" grade. For a certain class of modalities we prove that extraction is sound, in the sense that programs of natural number type have the same value before and after extraction. Soundness of extraction holds also for open programs, as long as all variables in the context are erasable, the context is consistent, and erased matches are not allowed for weak Σ-types
Fault localization for intelligent automation systems
No full textConventional programming of explicit control code is unsuitable for flexible and collaborative production systems. A model-based approach, which focuses on defining capabilities of a system, instead of specifying how to achieve them, provides an alternative for creating complex, scalable, and reliable systems. This is accomplished through the use of behavior models, and tools such as planning, synthesis, verification, and testing. However, developing such models is not without challenges, as it is possible to overlook or incorrectly specify potential behavior and constraints. This can result in unsolvable planning problems or plans that are invalid for other reasons. When plans are unobtainable, developers receive no feedback, which makes model adjustments a difficult and time-intensive task. This paper recognizes these challenges as crucial barriers for adopting model-based development of intelligent automation systems. To facilitate the development of such systems, an approach for detecting and localizing faults in behavior models is presented. Drawing inspiration from software fault localization techniques, the proposed method involves identifying suspicious resources, variables, and operations. The effectiveness of this approach is illustrated with an example use case
Joint optimal vehicle and recharging scheduling for mixed bus fleets under limited chargers
Get PDFOwing to the high acquisition costs, maintenance expenses, and inadequate charging infrastructure associated with electric buses, achieving a complete replacement of diesel buses with electric counterparts in the short term proves challenging. A substantial number of bus operators currently find themselves in a situation where they must integrate electric buses with their existing diesel fleets. Confronted with the constraints of limited electric bus range and charging infrastructure, the primary concern for bus operators is how to effectively utilize their mixed bus fleets to adhere to pre-established bus timetables while maximizing the deployment of electric buses, known for their zero pollution and cost-effective travel. Consequently, this paper introduces the concept of the joint optimization problem for vehicle and recharging scheduling within mixed bus fleets operating under constrained charging conditions. To tackle this issue, a mixed integer linear model is formulated to optimize the coordination of bus schedules and recharging activities within the context of limited charging infrastructure. By establishing a set of feasible charging activities, the problem of electric buses queuing for charging at constrained charging stations is transformed into a linear optimization model constraint. Numerical simulations are conducted within the real transit network of the Dalian Economic Development Zone in China. The results indicate that the judicious joint optimization of vehicle and charging scheduling significantly enhances the service frequency of electric buses while reducing operational costs for bus lines. Notably, the proportion of total trips performed by electric buses rises to 80.4%
Novel powertrain topologies for energy-efficient battery electric vehicles
Get PDFThe global transition towards sustainable transportation has underscored the importance of battery electric vehicles (BEVs), with a growing need for enhancement in powertrain energy efficiency to mitigate range anxiety and promote widespread adoption. In response to this need, there have been significant contributions from advancements on powertrain components, such as electric motors and inverters, towards increased energy efficiency. However, it is crucial to acknowledge that BEV powertrain efficiency is not simply a product of the efficiencies of electric motors and inverters. In this context, the exploration of novel powertrain topologies presents itself as an alternative and promising approach for further enhancing BEV powertrain efficiency. Moreover, when component-level advancements are integrated with innovative powertrain topologies, there is potential to push the boundaries of powertrain energy efficiency in BEVs.To this end, system simulation techniques are utilized in this thesis to evaluate different powertrain topologies in terms of energy efficiency over standard drive cycles, each operating under its optimal powertrain strategy. Specifically, two powertrain topologies are investigated in this thesis: 1) the Adaptive Front- and Rear-Axle Independently Driven (AFRID) powertrain features two clutches that enable the mechanical disconnection of two electric motors with differentiated high-efficiency operating areas, aiming to address the inherent high no-load losses of dual motor powertrains while utilizing the high-efficiency zone of each motor and leveraging torque distribution functionality to enhance overall efficiency. 2) The adjustable DC-link voltage powertrain allows the adjustment of DC-link voltage to an efficiency-favored level irrespective of the battery voltage, in response to dynamically changing driving conditions.The findings of this thesis indicate that the integration of both investigated powertrain topologies with state-of-the-art components can significantly enhance powertrain energy efficiency in comparison to conventional BEV powertrains. Importantly, these improvements in efficiency do not come at the expense of vehicle performance or driveability; in fact, vehicles equipped with these novel powertrain topologies are observed to exhibit superior performance and improved driveability, making them highly favorable options for the next generation of BEV powertrains
Refining the properties of the TOI-178 system with CHEOPS and TESS
No full textContext. The TOI-178 system consists of a nearby late K-dwarf transited by six planets in the super-Earth to mini-Neptune regime, with radii ranging from -1.1 to 2.9 R and orbital periods between 1.9 and 20.7 days. All planets but the innermost one form a chain of Laplace resonances. Mass estimates derived from a preliminary radial velocity (RV) dataset suggest that the planetary densities do not decrease in a monotonic way with the orbital distance to the star, contrary to what one would expect based on simple formation and evolution models. Aims. To improve the characterisation of this key system and prepare for future studies (in particular with JWST), we performed a detailed photometric study based on 40 new CHEOPS visits, one new TESS sector, and previously published CHEOPS, TESS, and NGTS data. Methods. First we updated the parameters of the host star using the new parallax from Gaia EDR3. We then performed a global analysis of the 100 transits contained in our data to refine the physical and orbital parameters of the six planets and study their transit timing variations (TTVs). We also used our extensive dataset to place constraints on the radii and orbital periods of potential additional transiting planets in the system. Results. Our analysis significantly refines the transit parameters of the six planets, most notably their radii, for which we now obtain relative precisions of -3%, with the exception of the smallest planet, b, for which the precision is 5.1%. Combined with the RV mass estimates, the measured TTVs allow us to constrain the eccentricities of planets c to g, which are found to be all below 0.02, as expected from stability requirements. Taken alone, the TTVs also suggest a higher mass for planet d than that estimated from the RVs, which had been found to yield a surprisingly low density for this planet. However, the masses derived from the current TTV dataset are very prior-dependent, and further observations, over a longer temporal baseline, are needed to deepen our understanding of this iconic planetary system
Signature of quantum criticality in cuprates by charge density fluctuations
Get PDFThe universality of the strange metal phase in many quantum materials is often attributed to the presence of a quantum critical point (QCP), a zero-temperature phase transition ruled by quantum fluctuations. In cuprates, where superconductivity hinders direct QCP observation, indirect evidence comes from the identification of fluctuations compatible with the strange metal phase. Here we show that the recently discovered charge density fluctuations (CDF) possess the right properties to be associated to a quantum phase transition. Using resonant x-ray scattering, we studied the CDF in two families of cuprate superconductors across a wide doping range (up to p = 0.22). At p* ≈ 0.19, the putative QCP, the CDF intensity peaks, and the characteristic energy Δ is minimum, marking a wedge-shaped region in the phase diagram indicative of a quantum critical behavior, albeit with anomalies. These findings strengthen the role of charge order in explaining strange metal phenomenology and provide insights into high-temperature superconductivity
Distinctive Processing Effects on Recovered Protein Isolates from Laurel (Bay) and Olive Leaves: A Comparative Study
Get PDFAlthough there is a well-known awareness of the nutritional potential of plant proteins, their utilization within food formulations is currently limited due to insufficient investigation of the functional properties or processing conditions. In this study, the protein contents of the remaining pulps of laurel (bay) (LL) and olive leaves (OL) after alcoholic washing (representing phenolic compound extraction), heat treatment (representing the usage of the leaves for tea brewing or as cooking aid), and deoiling process (representing oil extraction) were investigated. Bicinchoninic acid assay (BCA) indicated that the best protein yield was achieved with a direct isolation process after hexane oil removal. Both LL and OL isolates contained around 80% protein, but high temperature and alcohol content broke down the protein structure as well as decreased the final protein content (similar to 40%). Alcohol treatment appears to remove protein-bound phenols and increase fluorescence intensity in OL protein isolates while potentially causing structural alterations in LL proteins. In addition to a dramatic decrease in fluorescence intensity, the absolute zeta potentials of protein extracts of boiling OL and LL increased by 53 and 24%, respectively. The increased zeta potentials along with the decreased fluorescence intensity indicate the changes in the protein conformation and enhanced hydrophilicity of the protein structure, which can influence the functional properties of proteins. Protein extracts of deoiled LL had the highest Delta H value (180 mJ/mg), which is higher than other laurel and all olive protein samples. Laurel protein isolates became more thermally stable after hexane treatment. Moreover, the protein extracts after hexane treatment showed better emulsion capacity from both laurel (71.57%) and olive (61.87%). Water-binding capacity and thermal stability of the protein extracts from deoiled samples were higher than those of the other pretreatments, but the boiled samples showed higher oil-binding capacity due to protein denaturation. These findings indicate the importance of processing conditions in modulating protein properties for various applications
Symmetrical Doherty Power Amplifier with High Efficiency and Extended Bandwidth
No full textThis paper introduces a load modulation network for the Doherty power amplifier (PA). The proposed combiner network demonstrates inherent wideband characteristics and effectively addresses the impact of output parasitics resulting from the transistors, thereby achieving exceptional bandwidth performance. To validate the concept, a wideband prototype Doherty PA is designed and measured, employing GaN HEMT transistors. The experimental results exhibit a drain efficiency of 51-63 % at the peak output power and 41-53 % at 6-dB output power back-off across 1.6-2.7 GHz. Furthermore, the measured peak output power of 43.8\ub10.5 dBm within the same frequency range confirms the theoretical framework and demonstrates the promising potential of the proposed wideband Doherty PA for future applications in wireless transmitters
Untargeted plasma metabolomics and risk of colorectal cancer-an analysis nested within a large-scale prospective cohort
Get PDFBackgroundColorectal cancer (CRC) is a leading cause of cancer-related death worldwide, but if discovered at an early stage, the survival rate is high. The aim of this study was to identify novel markers predictive of future CRC risk using untargeted metabolomics.MethodsThis study included prospectively collected plasma samples from 902 CRC cases and 902 matched cancer-free control participants from the population-based Northern Sweden Health and Disease Study (NSHDS), which were obtained up to 26 years prior to CRC diagnosis. Using reverse-phase liquid chromatography-mass spectrometry (LC-MS), data comprising 5015 metabolic features were obtained. Conditional logistic regression was applied to identify potentially important metabolic features associated with CRC risk. In addition, we investigated if previously reported metabolite biomarkers of CRC risk could be validated in this study population.ResultsIn the univariable analysis, seven metabolic features were associated with CRC risk (using a false discovery rate cutoff of 0.25). Two of these could be annotated, one as pyroglutamic acid (odds ratio per one standard deviation increase = 0.79, 95% confidence interval, 0.70-0.89) and another as hydroxytigecycline (odds ratio per one standard deviation increase = 0.77, 95% confidence interval, 0.67-0.89). Associations with CRC risk were also found for six previously reported metabolic biomarkers of prevalent and/or incident CRC: sebacic acid (inverse association) and L-tryptophan, 3-hydroxybutyric acid, 9,12,13-TriHOME, valine, and 13-OxoODE (positive associations).ConclusionsThese findings suggest that although the circulating metabolome may provide new etiological insights into the underlying causes of CRC development, its potential application for the identification of individuals at higher risk of developing CRC is limited
Teaching Competencies
Get PDFIn search of a model of teaching competencies for engineering education, we led a focus group discussion as a workshop at SEFI2023, where we got practitioners’ perspectives on essential competencies for teaching. These were compared to a model of teaching competencies called the S2L model, developed and used at a technical university in Sweden. The aim of the workshop was to enrich the participants’ understanding of which competencies are essential for teaching and to challenge and improve the S2L model. After the workshop, the competencies collected from the participants were analysed using content analysis. The results show that the teaching competencies suggested by the participants fit into the S2L model, giving the model support. The participants agreed that a model for teaching competencies is very useful for educators, for example, in self-development and when supporting new colleagues, as a checklist and a common language. They also expressed that the workshop had widened their views on teaching competencies