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Localized patterns and semi-strong interaction, a unifying framework for reaction–diffusion systems (2021)

Al Saadi, Fahad ; Champneys, Alan ; Verschueren, Nicolas

Oxford University Press

In: IMA Journal of Applied Mathematics. 2021; Published 2021 Aug 19. doi: 10.1093/imamat/hxab036. [early online release]

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Publikationsdatum: 2021-08-19

Beschreibung: Systems of activator–inhibitor reaction–diffusion equations posed on an infinite line are studied using a variety of analytical and numerical methods. A canonical form is considered, which contains all known models with simple cubic autocatalytic nonlinearity and arbitrary constant and linear kinetics. Restricting attention to models that have a unique homogeneous equilibrium, this class includes the classical Schnakenberg and Brusselator models, as well as other systems proposed in the literature to model morphogenesis. Such models are known to feature Turing instability, when activator diffuses more slowly than inhibitor, leading to stable spatially periodic patterns. Conversely in the limit of small feed rates, semi-strong interaction asymptotic analysis shows existence of isolated spike-like patterns. This paper describes the broad bifurcation structures that connect these two regimes. A certain universal two-parameter state diagram is revealed in which the Turing bifurcation becomes sub-critical, leading to the onset of homoclinic snaking. This regime then morphs into the spike regime, with the outer-fold being predicted by the semi-strong asymptotics. A rescaling of parameters and field concentrations shows how this state diagram can be studied independently of the diffusion rates. Temporal dynamics is found to strongly depend on the diffusion ratio though. A Hopf bifurcation occurs along the branch of stable spikes, which is subcritical for small diffusion ratio, leading to collapse to the homogeneous state. As the diffusion ratio increases, this bifurcation typically becomes supercritical and interacts with the homoclinic snaking and also with a supercritical homogeneous Hopf bifurcation, leading to complex spatio-temporal dynamics. The details are worked out for a number of different models that fit the theory using a mixture of weakly nonlinear analysis, semi-strong asymptotics and different numerical continuation algorithms.

Print ISSN: 0272-4960

Digitale ISSN: 1464-3634

Thema: Mathematik

Publiziert von Oxford University Press im Namen von Institute of Mathematics and its Applications.

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In This Issue (2021)

Oxford University Press

In: Microscopy. 2021; 70(2): 1-4. Published 2021 Mar 24. doi: 10.1093/jmicro/dfab010.

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Publikationsdatum: 2021-03-24

Print ISSN: 2050-5698

Digitale ISSN: 2050-5701

Thema: Elektrotechnik, Elektronik, Nachrichtentechnik , Allgemeine Naturwissenschaft , Physik

Publiziert von Oxford University Press im Namen von Japanese Society of Microscopy.

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On singular equivalences of Morita type with level and Gorenstein algebras (2021)

Dalezios, Georgios

Oxford University Press

In: Bulletin of the London Mathematical Society. 2021; blms.12486. Published 2021 Mar 23. doi: 10.1112/blms.12486. [early online release]

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Publikationsdatum: 2021-03-23

Print ISSN: 0024-6093

Digitale ISSN: 1469-2120

Thema: Mathematik

Publiziert von Oxford University Press

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Robust nonconforming virtual element methods for general fourth-order problems with varying coefficients (2021)

Dedner, Andreas ; Hodson, Alice

Oxford University Press

In: IMA Journal of Numerical Analysis. 2021; Published 2021 Mar 17. doi: 10.1093/imanum/drab003. [early online release]

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Publikationsdatum: 2021-03-17

Beschreibung: We present a class of nonconforming virtual element methods for general fourth-order partial differential equations in two dimensions. We develop a generic approach for constructing the necessary projection operators and virtual element spaces. Optimal error estimates in the energy norm are provided for general linear fourth-order problems with varying coefficients. We also discuss fourth-order perturbation problems and present a novel nonconforming scheme which is uniformly convergent with respect to the perturbation parameter without requiring an enlargement of the space. Numerical tests are carried out to verify the theoretical results. We conclude with a brief discussion on how our approach can easily be applied to nonlinear fourth-order problems.

Print ISSN: 0272-4979

Digitale ISSN: 1464-3642

Thema: Mathematik

Publiziert von Oxford University Press im Namen von Institute of Mathematics and its Applications.

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Deep convolutional neural network image processing method providing improved signal-to-noise ratios in electron holography (2021)

Asari, Yusuke ; Terada, Shohei ; Tanigaki, Toshiaki ; [weitere]

Oxford University Press

In: Microscopy. 2021; Published 2021 Mar 17. doi: 10.1093/jmicro/dfab012. [early online release]

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Publikationsdatum: 2021-03-17

Beschreibung: An image identification method was developed with the aid of a deep convolutional neural network (CNN) and applied to the analysis of inorganic particles using electron holography. Despite significant variation in the shapes of α-Fe2O3 particles that were observed by transmission electron microscopy, this CNN-based method could be used to identify isolated, spindle-shaped particles that were distinct from other particles that had undergone pairing and/or agglomeration. The averaging of images of these isolated particles provided a significant improvement in the phase analysis precision of the electron holography observations. This method is expected to be helpful in the analysis of weak electromagnetic fields generated by nanoparticles showing only small phase shifts.

Print ISSN: 2050-5698

Digitale ISSN: 2050-5701

Thema: Elektrotechnik, Elektronik, Nachrichtentechnik , Allgemeine Naturwissenschaft , Physik

Publiziert von Oxford University Press im Namen von Japanese Society of Microscopy.

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A study of the skylight coverage ratio for air-conditioned atriumsin the hot and humid regions (2021)

Lou, Siwei ; Huang, Yu ; Xia, Dawei ; [weitere]

Oxford University Press

In: International Journal of Low Carbon Technologies. 2021; Published 2021 Mar 17. doi: 10.1093/ijlct/ctab023. [early online release]

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Publikationsdatum: 2021-03-17

Beschreibung: The skylight on the roof of an atrium can be popular for commercial malls to illuminate the core area of the building. However, the solar radiation and its heat can get into the building together with the daylight, causing excessive cooling load. This paper studies the daylighting and energy performances of skylight coverage area for the air-conditioned atriums in the hot and humid regions. The energy performance with different atrium heights, glass types and the coverage ratios of the skylight are studied. The daylight performance was simulated by the ray-tracing Radiance and was transferred into EnergyPlus for energy evaluations. The finding suggested that, for hot and humid climates, the skylight coverage ratio should be controlled carefully to prevent the excessive solar heat gain. When the on/off lighting control is applied, the total energy consumption of the single-floor cases (or of the top floor for the multi-floor cases) leveled off when the coverage ratio of the skylight reached 9%. Thus, the skylight is favorable to the energy saving of the low-rise or single-floor commercial buildings only under the current assumptions, as the ground of the atrium cannot be well illuminated while the excessive solar radiation gets into the building. The skylight should be shaded in cooling seasons to prevent the excessive solar heat gains.

Print ISSN: 1748-1317

Digitale ISSN: 1748-1325

Thema: Energietechnik , Maschinenbau

Publiziert von Oxford University Press

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Further Mathematics, student choice and transition to university: part 2—non-mathematics STEM degrees (2021)

Lyakhova, Sofya ; Neate, Andrew

Oxford University Press

In: Teaching Mathematics and its Applications. 2021; Published 2021 Mar 22. doi: 10.1093/teamat/hrab004. [early online release]

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Publikationsdatum: 2021-03-22

Beschreibung: This is the second paper reporting the results of a study investigating student choices of optional post-16 advanced-level (A-level) Mathematics and Further Mathematics qualifications in the UK and their impact on the transition from school to university mathematics. Here, the opinions of non-mathematics Science, Technology, Engineering and Mathematics (STEM) undergraduate students (all of whom had previously studied A-level Mathematics) were accessed via a survey and individual interviews. The study found that Further Mathematics qualifications are perceived as advantageous for non-mathematics STEM degrees by students once they are at university but not when making A-level choices. While the students often perceived mathematics positively, this appears to influence the choice of A-level Mathematics but not Further Mathematics. The lack of support from teachers and parents, the lack of perceived utility of Further Mathematics qualifications and a perception that Further Mathematics is only useful for studying a mathematics degree could all be factors affecting the uptake of Further Mathematics. The identified perceived impact of Further Mathematics on the university transition is linked to studying more pure mathematics which may give students a better understanding of how to apply mathematics in the context of their degree. Some comparisons between the findings in Parts 1 and 2 of the study are included which suggests that the Further Mathematics qualification is better serving students intending to study a non-mathematics STEM degree rather than mathematics itself.

Print ISSN: 0268-3679

Digitale ISSN: 1471-6976

Thema: Mathematik

Publiziert von Oxford University Press im Namen von Institute of Mathematics and its Applications.

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A novel hybrid liquefied natural gas process with absorption refrigeration integrated with molten carbonate fuel cell (2021)

Mehrpooya, Mehdi ; Bahramian, Parimah ; Pourfayaz, Fathollah ; [weitere]

Oxford University Press

In: International Journal of Low Carbon Technologies. 2021; Published 2021 Mar 24. doi: 10.1093/ijlct/ctab021. [early online release]

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Publikationsdatum: 2021-03-24

Beschreibung: The production of liquefied natural gas (LNG) is a high energy-consuming process. The study of ways to reduce energy consumption and consequently to reduce operational costs is imperative. Toward this purpose, this study proposes a hybrid system adopting a mixed refrigerant for the liquefaction of natural gas that is precooled with an ammonia/water absorption refrigeration (AR) cycle utilizing the exhaust heat of a molten carbonate fuel cell, 700°C and 2.74 bar, coupled with a gas turbine and a bottoming Brayton super-critical carbon dioxide cycle. The inauguration of the ammonia/water AR cycle to the LNG process increases the cooling load of the cycle by 10%, providing a 28.3-MW cooling load duty while having a 0.45 coefficient of performance. Employing the hybrid system reduces energy consumption, attaining 85% overall thermal efficiency, 53% electrical efficiency and 35% fuel cell efficiency. The hybrid system produces 6300 kg.mol.h−1 of LNG and 146.55 MW of electrical power. Thereafter, exergy and sensitivity analyses are implemented and, accordingly, the fuel cell had an 83% share of the exergy destruction and the whole system obtained a 95% exergy efficiency.

Print ISSN: 1748-1317

Digitale ISSN: 1748-1325

Thema: Energietechnik , Maschinenbau

Publiziert von Oxford University Press

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Exergetic performance analysis of low GWP alternative refrigerants for R404A in a refrigeration system (2021)

Altinkaynak, Mehmet

Oxford University Press

In: International Journal of Low Carbon Technologies. 2021; Published 2021 Feb 23. doi: 10.1093/ijlct/ctaa104. [early online release]

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Publikationsdatum: 2021-02-23

Beschreibung: According to the regulation of European Union laws in 2014, it was inevitable to switch to low global warming potential (GWP) fluids in the refrigeration systems where the R404A working fluid is currently used. The GWP of R404A is very high, and the potential for ozone depletion is zero. In this study, energetic and exergetic performance assessment of a theoretical refrigeration system was carried out for R404 refrigerant and its alternatives, comparatively. The analyses were made for R448A, R449A, R452A and R404A. The results of the analysis were presented separately in the tables and graphs. According to the results, the cooling system working with R448A exhibited the best performance with a coefficient of performance (COP) value of 2.467 within the alternatives of R404A followed by R449A and R452A, where the COP values were calculated as 2.419 and 2.313, respectively. In addition, the exergy efficiencies of the system were calculated as 20.62%, 20.22% and 19.33% for R448A, R449A and R452A, respectively. For the base calculations made for R404A, the COP of the system was estimated as 2.477, where the exergy efficiency was 20.71%. Under the same operating conditions, the total exergy destruction rates for R404A, R448A, R449A and R452A working fluids were found to be 3.201 kW, 3.217 kW, 3.298 kW and 3.488 kW, respectively. Furthermore, parametric analyses were carried out in order to investigate the effects of different system parameters such as evaporator and condenser temperature.

Print ISSN: 1748-1317

Digitale ISSN: 1748-1325

Thema: Energietechnik , Maschinenbau

Publiziert von Oxford University Press

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On holomorphic matrices on bordered Riemann surfaces (2021)

Leiterer, Jürgen

Oxford University Press

In: Bulletin of the London Mathematical Society. 2021; blms.12470. Published 2021 Feb 17. doi: 10.1112/blms.12470. [early online release]

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Publikationsdatum: 2021-02-17

Print ISSN: 0024-6093

Digitale ISSN: 1469-2120

Thema: Mathematik

Publiziert von Oxford University Press

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Efficient adjustment sets in causal graphical models with hidden variables (2021)

Smucler, E ; Sapienza, F ; Rotnitzky, A

Oxford University Press

In: Biometrika. 2021; Published 2021 Mar 17. doi: 10.1093/biomet/asab018. [early online release]

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Publikationsdatum: 2021-03-17

Beschreibung: We study the selection of adjustment sets for estimating the interventional mean under a point exposure dynamic treatment regime, that is, a treatment rule that depends on the subject’s covariates. We assume a non-parametric causal graphical model with, possibly, hidden variables and at least one adjustment set comprised of observable variables. We provide the definition of a valid adjustment set for a point exposure dynamic treatment regime, which generalizes the existing definition for a static intervention. We show that there exists an adjustment set, referred to as optimal minimal, that yields the non-parametric estimator of the interventional mean with the smallest asymptotic variance among those that are based on observable minimal adjustment sets. An observable minimal adjustment set is a valid adjustment set such that all its variables are observable and the removal of any variable from it destroys validity. We provide similar optimality results for the class of observable minimum adjustment sets, that is, valid observable adjustment sets of minimum cardinality among the observable adjustment sets. Moreover, we show that if either no variables are hidden or if all the observable variables are ancestors of either treatment, outcome, or the variables that are used to decide treatment, a globally optimal adjustment set exists. We provide polynomial time algorithms to compute the globally optimal, optimal minimal, and optimal minimum adjustment sets. Because static interventions can be viewed as a special case of dynamic regimes, all our results also apply for static interventions.

Print ISSN: 0006-3444

Digitale ISSN: 1464-3510

Thema: Biologie , Mathematik , Medizin

Publiziert von Oxford University Press

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Design of a New Distributed NoSQL Database with Distributed Hash Tables (2021)

San Román Guzmán, Agustín ; Valdeolmillos, Diego ; Rivas, Alberto ; [weitere]

Oxford University Press

In: Logic Journal of the IGPL. 2021; Published 2021 Mar 17. doi: 10.1093/jigpal/jzab003. [early online release]

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Publikationsdatum: 2021-03-17

Beschreibung: Databases play a fundamental role in today’s world, being used by most companies, especially those that offer services through the Internet. Today there is a wide variety of database models, each adapted for use according to the specific requirements of each application. Traditionally, the relational models with centralized architectures have been used mostly due to their simplicity and general-purpose query language, which made relational systems suitable for almost any application. However, with the growth of the Internet in recent decades, both in the number of users and in the amount of information, those centralized models began to suffer availability and scalability issues. To address those issues, the use of decentralized architectures and alternative database models began to arise, eventually replacing relational databases and centralized architectures when the requirements on availability and scalability are high. Those database models alternative to the traditional relational model are grouped under the name of NoSQL (Not only Structured Query Language). In this article, we present a NoSQL database developed as an end of degree work, with a flexible data model based on documents and a fully decentralized architecture based on the Gossip protocol for node discovery and a distributed hash table, in particular the rendezvous hashing algorithm, used to distribute and replicate the data across all the nodes. The main goals of the system are to achieve high availability (the data should be almost always accessible) and high scalability (the system should be able to scale by increasing the number of nodes to increase its capacity both on data and number of users). High availability is achieved thanks to the replication of the data, while high scalability is achieved by its decentralized architecture, which allows multiple entry points from the requests, and the data distribution, effectively increasing the database capacity by increasing the number of nodes.

Print ISSN: 1367-0751

Digitale ISSN: 1368-9894

Thema: Mathematik

Publiziert von Oxford University Press

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Notes on conjunctive and Quasi degrees (2021)

Chitaia, Irakli ; Omanadze, Roland ; Sorbi, Andrea

Oxford University Press

In: Journal of Logic and Computation. 2021; Published 2021 Mar 31. doi: 10.1093/logcom/exab026. [early online release]

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Publikationsdatum: 2021-03-31

Beschreibung: In this article we prove the following results: (i) Every hemimaximal set has minimal $c_{1}$-degree, i.e. if $B$ is hemimaximal and $A$ is a c.e. set such that $A le _{c_{1}} B$ then either $B leq _{{c}_{1}} A$ or $A$ is computable. (ii) The $sQ$-degree of a c.e. set contains either only one or infinitely many c.e. $c$-degrees. (iii) If $A,B$ are c.e. cylinders in the same $sQ_{1}$-degree and $A

Print ISSN: 0955-792X

Digitale ISSN: 1465-363X

Thema: Informatik , Mathematik

Publiziert von Oxford University Press

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Slice‐torus link invariants, combinatorial invariants and positivity conditions (2021)

Collari, Carlo

Oxford University Press

In: Bulletin of the London Mathematical Society. 2021; blms.12485. Published 2021 Mar 16. doi: 10.1112/blms.12485. [early online release]

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Publikationsdatum: 2021-03-16

Print ISSN: 0024-6093

Digitale ISSN: 1469-2120

Thema: Mathematik

Publiziert von Oxford University Press

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Link Floer homology also detects split links (2021)

Wang, Joshua

Oxford University Press

In: Bulletin of the London Mathematical Society. 2021; blms.12482. Published 2021 Feb 28. doi: 10.1112/blms.12482. [early online release]

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Publikationsdatum: 2021-02-28

Print ISSN: 0024-6093

Digitale ISSN: 1469-2120

Thema: Mathematik

Publiziert von Oxford University Press

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Optimally convergent mixed finite element methods for the stochastic Stokes equations (2021)

Feng, Xiaobing ; Prohl, Andreas ; Vo, Liet

Oxford University Press

In: IMA Journal of Numerical Analysis. 2021; Published 2021 Mar 17. doi: 10.1093/imanum/drab006. [early online release]

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Publikationsdatum: 2021-03-17

Beschreibung: We propose some new mixed finite element methods for the time-dependent stochastic Stokes equations with multiplicative noise, which use the Helmholtz decomposition of the driving multiplicative noise. It is known (Langa, J. A., Real, J. & Simon, J. (2003) Existence and regularity of the pressure for the stochastic Navier--Stokes equations. Appl. Math. Optim., 48, 195--210) that the pressure solution has low regularity, which manifests in suboptimal convergence rates for well-known inf-sup stable mixed finite element methods in numerical simulations; see Feng X., & Qiu, H. (Analysis of fully discrete mixed finite element methods for time-dependent stochastic Stokes equations with multiplicative noise. arXiv:1905.03289v2 [math.NA]). We show that eliminating this gradient part from the noise in the numerical scheme leads to optimally convergent mixed finite element methods and that this conceptual idea may be used to retool numerical methods that are well known in the deterministic setting, including pressure stabilization methods, so that their optimal convergence properties can still be maintained in the stochastic setting. Computational experiments are also provided to validate the theoretical results and to illustrate the conceptual usefulness of the proposed numerical approach.

Print ISSN: 0272-4979

Digitale ISSN: 1464-3642

Thema: Mathematik

Publiziert von Oxford University Press im Namen von Institute of Mathematics and its Applications.

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A forward internal calculus for model generation in S4 (2021)

Fiorentini, Camillo ; Ferrari, Mauro

Oxford University Press

In: Journal of Logic and Computation. 2021; Published 2021 Mar 29. doi: 10.1093/logcom/exab014. [early online release]

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Publikationsdatum: 2021-03-29

Beschreibung: We propose an internal calculus to check the satisfiability of a set of formulas in ${ oldsymbol {S4}}$. Our calculus directly supports model extraction and is designed so to implement a forward proof-search strategy that can be understood as a top-down construction of a model. We prove that the extracted models have minimal height.

Print ISSN: 0955-792X

Digitale ISSN: 1465-363X

Thema: Informatik , Mathematik

Publiziert von Oxford University Press

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Regularity of Spectral Stacks and Discreteness of Weight-Hearts (2021)

Sosnilo, Vladimir

Oxford University Press

In: Quarterly Journal of Mathematics. 2021; Published 2021 Mar 30. doi: 10.1093/qmath/haab017. [early online release]

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Publikationsdatum: 2021-03-30

Beschreibung: We study regularity in the context of connective ring spectra and spectral stacks. Parallel to that, we construct a weight structure on the category of compact quasi-coherent sheaves on spectral quotient stacks of the form $X=[operatorname{Spec} R/G]$ defined over a field, where R is a connective ${{mathcal{E}}_infty}$-k-algebra and G is a linearly reductive group acting on R. Under reasonable assumptions, we show that regularity of X is equivalent to regularity of R. We also show that if R is bounded, such a stack is discrete. This result can be interpreted in terms of weight structures and suggests a general phenomenon: for a symmetric monoidal stable $infty$-category with a compatible bounded weight structure, the existence of an adjacent t-structure satisfying a strong boundedness condition should imply discreteness of the weight-heart. We also prove a gluing result for weight structures and adjacent t-structures, in the setting of a semi-orthogonal decomposition of stable $infty$-categories.

Print ISSN: 0033-5606

Digitale ISSN: 1464-3847

Thema: Mathematik

Publiziert von Oxford University Press

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The Image Milnor Number and Excellent Unfoldings (2021)

Giménez Conejero, R ; Nuño-Ballesteros, J J

Oxford University Press

In: Quarterly Journal of Mathematics. 2021; Published 2021 Mar 27. doi: 10.1093/qmath/haab019. [early online release]

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Publikationsdatum: 2021-03-27

Beschreibung: We show three basic properties of the image Milnor number µI(f) of a germ $fcolon(mathbb{C}^{n},S) ightarrow(mathbb{C}^{n+1},0)$ with isolated instability. First, we show the conservation of the image Milnor number, from which one can deduce the upper semi-continuity and the topological invariance for families. Second, we prove the weak Mond’s conjecture, which states that µI(f) = 0 if and only if f is stable. Finally, we show a conjecture by Houston that any family $f_tcolon(mathbb{C}^{n},S) ightarrow(mathbb{C}^{n+1},0)$ with $mu_I(,f_t)$ constant is excellent in Gaffney’s sense. For technical reasons, in the last two properties, we consider only the corank 1 case.

Print ISSN: 0033-5606

Digitale ISSN: 1464-3847

Thema: Mathematik

Publiziert von Oxford University Press

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Defining Bicircular Matroids in Monadic Logic (2021)

Funk, Daryl ; Mayhew, Dillon ; Newman, Mike

Oxford University Press

In: Quarterly Journal of Mathematics. 2021; Published 2021 Mar 29. doi: 10.1093/qmath/haab020. [early online release]

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Publikationsdatum: 2021-03-29

Beschreibung: We conjecture that the class of frame matroids can be characterized by a sentence in the monadic second-order logic of matroids, and we prove that there is such a characterization for the class of bicircular matroids. The proof does not depend on an excluded-minor characterization.

Print ISSN: 0033-5606

Digitale ISSN: 1464-3847

Thema: Mathematik

Publiziert von Oxford University Press

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Approximate controllability of semilinear retarded stochastic differential system with non-instantaneous impulses: Fredholm theory approach (2021)

Anukiruthika, K ; Durga, N ; Muthukumar, P

Oxford University Press

In: IMA Journal of Mathematical Control and Information. 2021; Published 2021 Mar 18. doi: 10.1093/imamci/dnab006. [early online release]

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Publikationsdatum: 2021-03-18

Beschreibung: This article deals with the approximate controllability of semilinear retarded integrodifferential equations with non-instantaneous impulses governed by Poisson jumps in Hilbert space. The existence of a mild solution is established by using stochastic calculus and a suitable fixed point technique. The approximate controllability of the proposed non-linear stochastic differential system is obtained by employing the theory of interpolation spaces and Fredholm theory. Finally, applications to the stochastic heat equation and retarded type stochastic Benjamin–Bona–Mahony equation are provided to illustrate the developed theoretical results.

Print ISSN: 0265-0754

Digitale ISSN: 1471-6887

Thema: Mathematik

Publiziert von Oxford University Press im Namen von Institute of Mathematics and its Applications.

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Independent sets in hypergraphs with a forbidden link (2021)

Fox, Jacob ; He, Xiaoyu

Oxford University Press

In: Proceedings of the London Mathematical Society. 2021; plms.12400. Published 2021 Mar 17. doi: 10.1112/plms.12400. [early online release]

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Publikationsdatum: 2021-03-17

Print ISSN: 0024-6115

Digitale ISSN: 1460-244X

Thema: Mathematik

Publiziert von Oxford University Press

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Dimension Reduction for Covariates in Network Data (2021)

Zhao, Junlong ; Liu, Xiumin ; Wang, Hansheng ; [weitere]

Oxford University Press

In: Biometrika. 2021; Published 2021 Feb 09. doi: 10.1093/biomet/asab006. [early online release]

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Publikationsdatum: 2021-02-09

Beschreibung: Summary A problem of major interest in network data analysis is to explain the strength of connections using context information. To achieve this, we introduce a novel approach named network-supervised dimension reduction by projecting covariates onto low-dimensional spaces for revealing the linkage pattern, without assuming a model.We propose a new loss function for estimating the parameters in the resulting linear projection, based on the notion that closer proximity in the low-dimension projection renders stronger connections. Interestingly, the convergence rate of our estimator is shown to depend on a network effect factor which is the smallest number that can partition a graph in a way similar to the graph coloring problem. Our methodology has interesting connections to principal component analysis and linear discriminant analysis, which we exploit for clustering and community detection. The methodology developed is further illustrated by numerical experiments and the analysis of a pulsar candidates data in astronomy.

Print ISSN: 0006-3444

Digitale ISSN: 1464-3510

Thema: Biologie , Mathematik , Medizin

Publiziert von Oxford University Press

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Automatic rational approximation and linearization of nonlinear eigenvalue problems (2021)

Lietaert, Pieter ; Meerbergen, Karl ; Pérez, Javier ; [weitere]

Oxford University Press

In: IMA Journal of Numerical Analysis. 2021; Published 2021 Feb 17. doi: 10.1093/imanum/draa098. [early online release]

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Publikationsdatum: 2021-02-17

Beschreibung: We present a method for solving nonlinear eigenvalue problems (NEPs) using rational approximation. The method uses the Antoulas–Anderson algorithm (AAA) of Nakatsukasa, Sète and Trefethen to approximate the NEP via a rational eigenvalue problem. A set-valued variant of the AAA algorithm is also presented for building low-degree rational approximations of NEPs with a large number of nonlinear functions. The rational approximation is embedded in the state-space representation of a rational polynomial by Su and Bai. This procedure perfectly fits the framework of the compact rational Krylov methods (CORK and TS-CORK), allowing solve large-scale NEPs to be efficiently solved. One advantage of our method, compared to related techniques such as NLEIGS and infinite Arnoldi, is that it automatically selects the poles and zeros of the rational approximations. Numerical examples show that the presented framework is competitive with NLEIGS and usually produces smaller linearizations with the same accuracy but with less effort for the user.

Print ISSN: 0272-4979

Digitale ISSN: 1464-3642

Thema: Mathematik

Publiziert von Oxford University Press im Namen von Institute of Mathematics and its Applications.

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A study on evaluation systems for optimized design GSHP and ES technologies used in HVAC systems (2021)

Zhou, Ruifang ; Gong, Dejian ; Zhu, Shengjie ; [weitere]

Oxford University Press

In: International Journal of Low Carbon Technologies. 2021; Published 2021 Feb 24. doi: 10.1093/ijlct/ctab017. [early online release]

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Publikationsdatum: 2021-02-24

Beschreibung: Due to the lack of suitable evaluation systems for heating, ventilation, air-conditioning (HVAC) systems with ground source heat pump (GSHP) and energy storage (ES) technologies, it is difficult to design a building HVAC system to achieve optimized design with regard to investment cost, energy saving and environmental protection. This is a study on developing a fuzzy evaluation system by including GSHP and ES with comprehensively determined weights into an HVAC system. A questionnaire method was used and the answers from 21 HVAC experts were analyzed to facilitate the modeling. Taking a commercial integrated project in Nanjing as an engineering case, the evaluation system was tested. If the system with a comprehensive merit value of 0.303 is adopted, the annual operating cost is reduced by 32.5%, the annual total life cycle cost is reduced by 26.5% and the primary energy consumption and carbon emissions are reduced by 10.5%, with the initial investment increased by 6.5%. This study revealed that the newly developed evaluation system is very useful for realizing the optimal design of HVAC systems.

Print ISSN: 1748-1317

Digitale ISSN: 1748-1325

Thema: Energietechnik , Maschinenbau

Publiziert von Oxford University Press

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General ways to improve FCR-adjusted selective confidence intervals (2021)

Zhao, Haibing

Oxford University Press

In: Biometrika. 2021; Published 2021 Feb 16. doi: 10.1093/biomet/asab010. [early online release]

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Publikationsdatum: 2021-02-16

Beschreibung: Recently, post-selection inference on thousands of parameters has attracted considerable research interest. Specifically, Benjamini & Yekutieli (2005) considered constructing confidence intervals after selection. They proposed adjusting the confidence levels of marginal confidence intervals for the selected parameters to ensure control of the false coverage-statement rate. Although Benjamini-Yekutieliâ€™s confidence intervals are widely used, they are uniformly inflated. In this article, two methods are proposed to narrow Benjamini-Yekutieliâ€™s confidence intervals. The first method improves the confidence intervals by incorporating the selection event into the calculation. The second method further narrows confidence intervals in which some parameters are selected with very small probabilities, which results in underutilization of the target level for control of the false coverage-statement rate. A breast cancer dataset is analyzed to compare the methods.

Print ISSN: 0006-3444

Digitale ISSN: 1464-3510

Thema: Biologie , Mathematik , Medizin

Publiziert von Oxford University Press

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Interpoint-Ranking Sign Covariance for Test of Independence (2021)

Moon, Haeun ; Chen, Kehui

Oxford University Press

In: Biometrika. 2021; Published 2021 Feb 16. doi: 10.1093/biomet/asab011. [early online release]

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Publikationsdatum: 2021-02-16

Beschreibung: Summary We generalize the sign covariance introduced by Bergsma & Dassios (2014) to multivariate random variables and beyond. The new interpoint-ranking sign covariance is applicable to general types of random objects as long as a meaningful similarity measure can be defined, and it is shown to be zero if and only if the two random variables are independent. The test statistic is a U-statistic, whose large sample behavior guarantees that the proposed test is consistent against general types of alternatives. Numerical experiments and data analyses demonstrate the great empirical performance of the proposed method.

Print ISSN: 0006-3444

Digitale ISSN: 1464-3510

Thema: Biologie , Mathematik , Medizin

Publiziert von Oxford University Press

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On bivalent semantics and natural deduction for some infectious logics (2021)

Belikov, Alex

Oxford University Press

In: Logic Journal of the IGPL. 2021; Published 2021 Feb 18. doi: 10.1093/jigpal/jzaa071. [early online release]

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Publikationsdatum: 2021-02-18

Beschreibung: In this work, we propose a variant of so-called informational semantics, a technique elaborated by Voishvillo, for two infectious logics, Deutsch’s ${mathbf{S}_{mathbf{fde}}}$ and Szmuc’s $mathbf{dS}_{mathbf{fde}}$. We show how the machinery of informational semantics can be effectively used to analyse truth and falsity conditions of disjunction and conjunction. Using this technique, it is possible to claim that disjunction and conjunction can be rightfully regarded as such, a claim which was disputed in the recent literature. Both ${mathbf{S}_{mathbf{fde}}}$ and $mathbf{dS}_{mathbf{fde}}$ are formalized in terms of natural deduction. This allows us to solve several problems: to develop a natural deduction calculus for ${mathbf{S}_{mathbf{fde}}}$ containing the standard form of disjunction elimination (in contrast to the calculus by Petrukhin), to introduce the first natural deduction calculus for $mathbf{dS}_{mathbf{fde}}$ and to reflect the fundamental symmetry between ${mathbf{S}_{mathbf{fde}}}$ and $mathbf{dS}_{mathbf{fde}}$ on proof-theoretical level forming a convenient basis for obtaining their well-known extensions $mathbf{K}^{mathbf{w}}_{mathbf{3}}$ and $mathbf{PWK}$.

Print ISSN: 1367-0751

Digitale ISSN: 1368-9894

Thema: Mathematik

Publiziert von Oxford University Press

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On the classic paradox of infinity and a related function (2021)

Wijeratne, Chanakya ; Zazkis, Rina

Oxford University Press

In: Teaching Mathematics and its Applications. 2021; Published 2021 Feb 25. doi: 10.1093/teamat/hrab001. [early online release]

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Publikationsdatum: 2021-02-25

Beschreibung: In this study we consider a classic paradox of infinity and its variations and suggest how the sources of misleading intuition can be analysed using the concept of uniform convergence of functions. We then examine how six mathematics honour students engage with a variation of the paradox. Despite their advanced mathematical training, the participants experienced considerable difficulty in addressing the presented paradoxical situation. Drawing on data from written responses and individual interviews, we describe the students’ approaches in an attempt to reconcile their intuitive perceptions with their mathematical computations.

Print ISSN: 0268-3679

Digitale ISSN: 1471-6976

Thema: Mathematik

Publiziert von Oxford University Press im Namen von Institute of Mathematics and its Applications.

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Braids groups and mapping class groups: The Birman–Hilden theory (2021)

Margalit, Dan ; Winarski, Rebecca R.

Oxford University Press

In: Bulletin of the London Mathematical Society. 2021; blms.12456. Published 2021 Feb 02. doi: 10.1112/blms.12456. [early online release]

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Publikationsdatum: 2021-02-02

Print ISSN: 0024-6093

Digitale ISSN: 1469-2120

Thema: Mathematik

Publiziert von Oxford University Press

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Magnitude homology of metric spaces and order complexes (2021)

Kaneta, Ryuki ; Yoshinaga, Masahiko

Oxford University Press

In: Bulletin of the London Mathematical Society. 2021; blms.12469. Published 2021 Feb 18. doi: 10.1112/blms.12469. [early online release]

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Publikationsdatum: 2021-02-18

Print ISSN: 0024-6093

Digitale ISSN: 1469-2120

Thema: Mathematik

Publiziert von Oxford University Press

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Imaging Simulation of Charged Nanowires in TEM with Large Defocus Distance (2021)

Shi, Te ; Liu, Shikai ; Tian, H ; [weitere]

Oxford University Press

In: Microscopy. 2021; Published 2021 Feb 26. doi: 10.1093/jmicro/dfab008. [early online release]

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Publikationsdatum: 2021-02-26

Beschreibung: In transmission electron microscope (TEM), both the amplitude and phase of electron beam change when electrons traverse a specimen. The amplitude is easily obtained by the square root of the intensity of a TEM image, while the phase affects defocused images. In order to obtain the phase map and verify the theoretical model of the interaction between electron beam and specimen, a lot of simulations have been performed by researchers. In this work, we have simulated defocus images of a SiC nanowire in TEM with the method of electron optics. Mean inner potential and charge distribution on the nanowire have been considered in the simulation. Besides, due to electron scattering coherence loss of the electron beam has been introduced. A dynamic process with Bayesian optimization was used in the simulation. With the infocus image as input and by adjusting fitting parameters the defocus image is determined with a reasonable charge distribution. The calculated defocus images are in a good agreement with the experimental ones. Here, we present a complete solution and verification method for solving nanoscale charge distribution in TEM.

Print ISSN: 2050-5698

Digitale ISSN: 2050-5701

Thema: Elektrotechnik, Elektronik, Nachrichtentechnik , Allgemeine Naturwissenschaft , Physik

Publiziert von Oxford University Press im Namen von Japanese Society of Microscopy.

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Performance characteristics of a heat pump using renewable transcritical CO2 refrigerant for heating water (2021)

Yunus, Mohammed ; Oreijah, Mowffaq M

Oxford University Press

In: International Journal of Low Carbon Technologies. 2021; Published 2021 Feb 23. doi: 10.1093/ijlct/ctab009. [early online release]

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Publikationsdatum: 2021-02-23

Beschreibung: Among non-toxic and inflammable working fluids, carbon dioxide (CO2) proving a possible choice of refrigerant is gaining full status because of its reducing capacity of global warming and ozone depletion. Heat pump (HP) equipment uses energy more rationally to heat water by reducing emissions and global warming caused by conventional refrigerants. HP capability demands an environmentally friendly refrigerant for their full utilization and high energy saving as well to attaining higher coefficient of performance (COP) without much design corrections. CO2 is checked for sustainability to eliminate the standardized refrigerants such as chlorofluorocarbons (CFC) and hydro-CFC. In this work, the performance of CO2 as an alternate refrigerant in HP for heating water at different pressure, flow rates, evaporator fan speed and preheating have been investigated. HP is accommodated with two condensers. The results showed that the increased mass flow rate had increased COP, overall heat transfer (HT) coefficient (U) and HT. However, logarithmic mean temperature difference was decreased for increasing evaporator’s fan speed and pressure. The outlet water temperature (TWO) of second condenser increased with decreasing water flow rate. Improved COP, HT and TWO of HP are observed from the experimental evaluation in case of preheating of water.

Print ISSN: 1748-1317

Digitale ISSN: 1748-1325

Thema: Energietechnik , Maschinenbau

Publiziert von Oxford University Press

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A rapid harmonic detection method for grid-connected photovoltaic when three-phase voltage is unbalanced (2021)

Wu, Tiezhou ; Wang, An ; Xu, Yawen

Oxford University Press

In: International Journal of Low Carbon Technologies. 2021; Published 2021 Feb 19. doi: 10.1093/ijlct/ctab015. [early online release]

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Publikationsdatum: 2021-02-19

Beschreibung: By using power electronic devices, photovoltaic grid-connected power generation may inject harmonics into the power system. As the photovoltaic grid-connected inverter has the same basic structure as the active power filter, so the unified control of the photovoltaic grid and active filtering can be achieved. When the current unified control system compensates harmonics of the grid side, it mainly uses ip-iq harmonic detection method, which is based on instantaneous reactive power theory. When the three-phase voltage is unbalanced, the method has a large voltage phase angle detection error and the signal of the low-pass filter tracking system is long, detection time delay and even failure occur. This paper proposes an improved fast harmonic detection method. When phase deviation or amplitude change occurs to the three-phase voltage, the positive and negative-sequence voltages are simultaneously park transformed. The negative-sequence component is filtered by the current average module to obtain the fundamental amount of the voltage, then the phase angle of the positive-sequence voltage is accurately calculated to improve the harmonic current detection accuracy. Through the study of the integral method, it is found that the least common multiple of each harmonic period can be used as the integral interval, and the integral value is also zero, so the detection delay time is reduced by replacing the low-pass filter with an integration module. The simulation results show that the proposed harmonic detection algorithm can accurately detect harmonics when the three-phase voltage is unbalanced, and about 0.057 s improve the harmonic detection speed compared with the commonly used ip-iq method.

Print ISSN: 1748-1317

Digitale ISSN: 1748-1325

Thema: Energietechnik , Maschinenbau

Publiziert von Oxford University Press

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IN THIS ISSUE (2021)

Oxford University Press

In: Microscopy. 2021; 70(1): 1-4. Published 2021 Feb 01. doi: 10.1093/jmicro/dfaa068.

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Publikationsdatum: 2021-02-01

Print ISSN: 2050-5698

Digitale ISSN: 2050-5701

Thema: Elektrotechnik, Elektronik, Nachrichtentechnik , Allgemeine Naturwissenschaft , Physik

Publiziert von Oxford University Press im Namen von Japanese Society of Microscopy.

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A spectral-in-time Newton–Krylov method for nonlinear PDE-constrained optimization (2021)

Güttel, Stefan ; Pearson, John W

Oxford University Press

In: IMA Journal of Numerical Analysis. 2021; Published 2021 Feb 25. doi: 10.1093/imanum/drab011. [early online release]

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Publikationsdatum: 2021-02-25

Beschreibung: We devise a method for nonlinear time-dependent partial-differential-equation-constrained optimization problems that uses a spectral-in-time representation of the residual, combined with a Newton–Krylov method to drive the residual to zero. We also propose a preconditioner to accelerate this scheme. Numerical results indicate that this method can achieve fast and accurate solution of nonlinear problems for a range of mesh sizes and problem parameters. The numbers of outer Newton and inner Krylov iterations required to reach the attainable accuracy of a spatial discretization are robust with respect to the number of collocation points in time and also do not change substantially when other problem parameters are varied.

Print ISSN: 0272-4979

Digitale ISSN: 1464-3642

Thema: Mathematik

Publiziert von Oxford University Press im Namen von Institute of Mathematics and its Applications.

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Heterogeneity-aware and communication-efficient distributed statistical inference (2021)

Duan, Rui ; Ning, Yang ; Chen, Yong

Oxford University Press

In: Biometrika. 2021; Published 2021 Feb 12. doi: 10.1093/biomet/asab007. [early online release]

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Publikationsdatum: 2021-02-12

Beschreibung: In multicentre research, individual-level data are often protected against sharing across sites. To overcome the barrier of data sharing, many distributed algorithms, which only require sharing aggregated information, have been developed. The existing distributed algorithms usually assume the data are homogeneously distributed across sites. This assumption ignores the important fact that the data collected at different sites may come from various subpopulations and environments, which can lead to heterogeneity in the distribution of the data. Ignoring the heterogeneity may lead to erroneous statistical inference. In this paper, we propose distributed algorithms which account for the heterogeneous distributions by allowing site-specific nuisance parameters. The proposed methods extend the surrogate likelihood approach (Wang et al., 2017; Jordan et al., 2018) to the heterogeneous setting by applying a novel density ratio tilting method to the efficient score function. The proposed algorithms maintain the same communication cost as existing communication-efficient algorithms. We establish a non-asymptotic risk bound for the proposed distributed estimator and its limiting distribution in the two-index asymptotic setting which allows both sample size per site and the number of sites to go to infinity. In addition, we show that the asymptotic variance of the estimator attains the Cramér-Rao lower bound when the number of sites is in rate smaller than the sample size at each site. Finally, we use simulation studies and a real data application to demonstrate the validity and feasibility of the proposed methods.

Print ISSN: 0006-3444

Digitale ISSN: 1464-3510

Thema: Biologie , Mathematik , Medizin

Publiziert von Oxford University Press

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The global finite-time synchronization of a class of chaotic systems via the variable-substitution and feedback control (2021)

Chen, Yun ; Xu, Yanyi ; Lin, Qian

Oxford University Press

In: IMA Journal of Mathematical Control and Information. 2021; Published 2021 Feb 13. doi: 10.1093/imamci/dnaa041. [early online release]

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Publikationsdatum: 2021-02-13

Beschreibung: This paper deals with the global finite-time synchronization of a class of third-order chaotic systems with some intersecting nonlinearities, which cover many famous chaotic systems. First, a simple, continuous and dimension-reducible control by the name of the variable-substitution and feedback control is designed to construct a master–slave finite-time synchronization scheme. Then, a global finite-time synchronization criterion for the synchronization scheme is proven and the synchronization time is analytically estimated. Subsequently, the criterion and optimization technique are applied to the well-known brushless direct current motor (BLDCM) system and the classic Lorenz system, respectively, further obtaining some new optimized synchronization criteria in the form of algebra. Two numerical examples for the BLDCM system and a numerical example for the Lorenz system are simulated and analyzed to verify the effectiveness of the theoretical results obtained in this paper.

Print ISSN: 0265-0754

Digitale ISSN: 1471-6887

Thema: Mathematik

Publiziert von Oxford University Press im Namen von Institute of Mathematics and its Applications.

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Statistical inference on shape- and size-indexes for counting processes (2021)

Sun, Yifei ; Chiou, Sy Han ; Marr, Kieren A ; [weitere]

Oxford University Press

In: Biometrika. 2021; Published 2021 Feb 12. doi: 10.1093/biomet/asab008. [early online release]

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Publikationsdatum: 2021-02-12

Beschreibung: Single-index models have gained increased popularity in time-to-event analysis owing to their model flexibility and advantage in dimension reduction. In this paper, we propose a semiparametric framework for the rate function of a recurrent event counting process by modelling its size and shape components with single-index models. With additional monotone constraints on the two link functions for the size and shape components, the proposed model possesses the desired directional interpretability of covariate effects and encompasses many commonly used models as special cases. To tackle the analytical challenges arising from leaving the two link functions unspecified, we develop a two-step rank-based estimation procedure to estimate the regression parameters with or without informative censoring. The proposed estimators are asymptotically normal, with a root-n convergence rate. To guide model selection, we develop hypothesis testing procedures for checking shape- and size-independence. Simulation studies and a data example on a hematopoietic stem cell transplantation study are presented to illustrate the proposed methodology.

Print ISSN: 0006-3444

Digitale ISSN: 1464-3510

Thema: Biologie , Mathematik , Medizin

Publiziert von Oxford University Press

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Minimal crossing number implies minimal supporting genus (2021)

Boden, Hans U. ; Rushworth, William

Oxford University Press

In: Bulletin of the London Mathematical Society. 2021; blms.12491. Published 2021 Apr 15. doi: 10.1112/blms.12491. [early online release]

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Publikationsdatum: 2021-04-15

Print ISSN: 0024-6093

Digitale ISSN: 1469-2120

Thema: Mathematik

Publiziert von Oxford University Press

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Estimation under matrix quadratic loss and matrix superharmonicity (2021)

Matsuda, T ; Strawderman, W E

Oxford University Press

In: Biometrika. 2021; Published 2021 Apr 20. doi: 10.1093/biomet/asab025. [early online release]

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Publikationsdatum: 2021-04-20

Beschreibung: Summary We investigate estimation of a normal mean matrix under the matrix quadratic loss. Improved estimation under the matrix quadratic loss implies improved estimation of any linear combination of the columns under the quadratic loss. First, an unbiased estimate of risk is derived and the Efron–Morris estimator is shown to be minimax. Next, a notion of matrix superharmonicity for matrix-variate functions is introduced and shown to have analogous properties with usual superharmonic functions, which may be of independent interest. Then, we show that the generalized Bayes estimator with respect to a matrix superharmonic prior is minimax. We also provide a class of matrix superharmonic priors that includes the previously proposed generalization of Stein’s prior. Numerical results demonstrate that matrix superharmonic priors work well for low rank matrices.

Print ISSN: 0006-3444

Digitale ISSN: 1464-3510

Thema: Biologie , Mathematik , Medizin

Publiziert von Oxford University Press

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Solving block low-rank linear systems by LU factorization is numerically stable (2021)

Higham, Nicholas J ; Mary, Theo

Oxford University Press

In: IMA Journal of Numerical Analysis. 2021; Published 2021 Apr 20. doi: 10.1093/imanum/drab020. [early online release]

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Publikationsdatum: 2021-04-20

Beschreibung: Block low-rank (BLR) matrices possess a blockwise low-rank property that can be exploited to reduce the complexity of numerical linear algebra algorithms. The impact of these low-rank approximations on the numerical stability of the algorithms in floating-point arithmetic has not previously been analysed. We present rounding error analysis for the solution of a linear system by LU factorization of BLR matrices. Assuming that a stable pivoting scheme is used, we prove backward stability: the relative backward error is bounded by a modest constant times $varepsilon $, where the low-rank threshold $varepsilon $ is the parameter controlling the accuracy of the blockwise low-rank approximations. In addition to this key result, our analysis offers three new insights into the numerical behaviour of BLR algorithms. First, we compare the use of a global or local low-rank threshold and find that a global one should be preferred. Second, we show that performing intermediate recompressions during the factorization can significantly reduce its cost without compromising numerical stability. Third, we consider different BLR factorization variants and determine the update–compress–factor variant to be the best. Tests on a wide range of matrices from various real-life applications show that the predictions from the analysis are realized in practice.

Print ISSN: 0272-4979

Digitale ISSN: 1464-3642

Thema: Mathematik

Publiziert von Oxford University Press im Namen von Institute of Mathematics and its Applications.

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Discrete locally finite full groups of Cantor set homeomorphisms (2021)

Garrido, Alejandra ; Reid, Colin D.

Oxford University Press

In: Bulletin of the London Mathematical Society. 2021; blms.12496. Published 2021 Apr 30. doi: 10.1112/blms.12496. [early online release]

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Publikationsdatum: 2021-04-30

Print ISSN: 0024-6093

Digitale ISSN: 1469-2120

Thema: Mathematik

Publiziert von Oxford University Press

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Uniqueness of minimal diffeomorphisms between surfaces (2021)

Marković, Vladimir

Oxford University Press

In: Bulletin of the London Mathematical Society. 2021; blms.12493. Published 2021 Apr 26. doi: 10.1112/blms.12493. [early online release]

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Publikationsdatum: 2021-04-26

Print ISSN: 0024-6093

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Thema: Mathematik

Publiziert von Oxford University Press

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Identifiability of causal effects with multiple causes and a binary outcome (2021)

Kong, Dehan ; Yang, Shu ; Wang, Linbo

Oxford University Press

In: Biometrika. 2021; Published 2021 Mar 12. doi: 10.1093/biomet/asab016. [early online release]

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Publikationsdatum: 2021-03-12

Beschreibung: Unobserved confounding presents a major threat to causal inference from observational studies. Recently, several authors suggest that this problem may be overcome in a shared confounding setting where multiple treatments are independent given a common latent confounder. It has been shown that under a linear Gaussian model for the treatments, the causal effect is not identifiable without parametric assumptions on the outcome model. In this note, we show that the causal effect is indeed identifiable if we assume a general binary choice model for the outcome with a non-probit link. Our identification approach is based on the incongruence between Gaussianity of the treatments and latent confounder, andnon-Gaussianity of a latent outcome variable. We further develop a two-step likelihood-based estimation procedure.

Print ISSN: 0006-3444

Digitale ISSN: 1464-3510

Thema: Biologie , Mathematik , Medizin

Publiziert von Oxford University Press

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Lp estimates for multilinear convolution operators defined with spherical measure (2021)

Shrivastava, Saurabh ; Shuin, Kalachand

Oxford University Press

In: Bulletin of the London Mathematical Society. 2021; blms.12483. Published 2021 Mar 02. doi: 10.1112/blms.12483. [early online release]

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Publikationsdatum: 2021-03-02

Print ISSN: 0024-6093

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Thema: Mathematik

Publiziert von Oxford University Press

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Intuitionistic multi-agent subatomic natural deduction for belief and knowledge (2021)

Więckowski, Bartosz

Oxford University Press

In: Journal of Logic and Computation. 2021; Published 2021 Mar 26. doi: 10.1093/logcom/exab013. [early online release]

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Publikationsdatum: 2021-03-26

Beschreibung: This paper proposes natural deduction systems for the representation of inferences in which several agents participate in deriving conclusions about what they believe or know, where belief and knowledge are understood in an intuitionistic sense. Multi-agent derivations in these systems may involve relatively complex belief (resp. knowledge) constructions which may include forms of nested, reciprocal, shared, distributed or universal belief/knowledge as well as attitudes de dicto/re/se. The systems consist of two main components: multi-agent belief bases which assign to each agent a subatomic system that represents the agent’s beliefs concerning atomic sentences and a set of multi-agent labelled rules for logically compound formulae. Derivations in these systems normalize. Moreover, normal derivations possess the subexpression property (a refinement of the subformula property) which makes them fully analytic. Relying on the normalization result, a proof-theoretic approach to the semantics of the intensional operators for intuitionistic belief/knowledge is presented which explains their meaning entirely by appeal to the structure of derivations. Importantly, this proof-theoretic semantics is autarkic with respect to its foundations as the systems (unlike, e.g. external/labelled proof systems which internalize possible worlds truth conditions) are not defined on the basis of a possible worlds semantics. Detailed applications to a logical puzzle (McCarthy’s three wise men puzzle) and to a semantical difficulty (Geach’s problem of intentional identity), respectively, illustrate the systems. The paper also provides comparisons with other approaches to intuitionistic belief/knowledge and multi-agent natural deduction.

Print ISSN: 0955-792X

Digitale ISSN: 1465-363X

Thema: Informatik , Mathematik

Publiziert von Oxford University Press

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State-of-charge estimation for second-life lithium-ion batteries based on cell difference model and adaptive fading unscented Kalman filter algorithm (2021)

Du, Banghua ; Yu, Zhang ; Yi, Shuhao ; [weitere]

Oxford University Press

In: International Journal of Low Carbon Technologies. 2021; Published 2021 Mar 16. doi: 10.1093/ijlct/ctab019. [early online release]

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Publikationsdatum: 2021-03-16

Beschreibung: Lithium-ion batteries retired from electric vehicles can provide considerable economic benefits when they are retired for secondary use. However, retired batteries after screening and restructuring still face the problem of inaccurate battery pack state-of-charge (SOC) estimation due to the existence of extreme inconsistency. To solve this problem, an adaptive fading unscented Kalman filtering (AFUKF) algorithm based on the cell difference model (CDM) is proposed in this paper for improving the accuracy of SOC estimation of retired lithium-ion battery packs. Firstly, an improved CDM based on a hypothetical Rint model is developed based on a second-order resistor/capacitor equivalent circuit model. Secondly, an AFUKF algorithm is developed to improve the adaptability and robustness of local state estimation against process modelling errors. Finally, characteristic data are obtained by conducting discharge tests on the screened retired lithium-ion batteries under specific operating conditions. The proposed method can improve the accuracy of SOC estimation of retired lithium-ion battery packs and provide a new idea for SOC estimation of retired lithium-ion battery packs, as shown by the simulated real experimental data.

Print ISSN: 1748-1317

Digitale ISSN: 1748-1325

Thema: Energietechnik , Maschinenbau

Publiziert von Oxford University Press

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The principal p‐blocks with four irreducible characters (2021)

Koshitani, Shigeo ; Sakurai, Taro

Oxford University Press

In: Bulletin of the London Mathematical Society. 2021; blms.12488. Published 2021 Mar 22. doi: 10.1112/blms.12488. [early online release]

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Publikationsdatum: 2021-03-22

Print ISSN: 0024-6093

Digitale ISSN: 1469-2120

Thema: Mathematik

Publiziert von Oxford University Press

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Preface (2021)

Oxford University Press

In: Journal of Logic and Computation. 2021; Published 2021 Mar 17. doi: 10.1093/logcom/exab012. [early online release]

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Publikationsdatum: 2021-03-17

Print ISSN: 0955-792X

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Thema: Informatik , Mathematik

Publiziert von Oxford University Press

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Inverses of Matérn Covariances on Grids (2021)

Guinness, Joseph

Oxford University Press

In: Biometrika. 2021; Published 2021 Mar 12. doi: 10.1093/biomet/asab017. [early online release]

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Publikationsdatum: 2021-03-12

Beschreibung: We conduct a study of the aliased spectral densities of Matérn covariance functions on a regular grid of points, providing clarity on the properties of a popular approximation based on stochastic partial differential equations. While others have shown that it can approximate the covariance function well, we find that it assigns too much power at high frequencies and does not provide increasingly accurate approximations to the inverse as the grid spacing goes to zero, except in the one-dimensional exponential covariance case.

Print ISSN: 0006-3444

Digitale ISSN: 1464-3510

Thema: Biologie , Mathematik , Medizin

Publiziert von Oxford University Press

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Deformations Of Multivalued Harmonic Functions (2021)

Donaldson, Simon

Oxford University Press

In: Quarterly Journal of Mathematics. 2021; Published 2021 Mar 31. doi: 10.1093/qmath/haab018. [early online release]

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Publikationsdatum: 2021-03-31

Beschreibung: We consider harmonic sections of a bundle over the complement of a codimension 2 submanifold in a Riemannian manifold, which can be thought of as multivalued harmonic functions. We prove a result to the effect that these are stable under small deformations of the data. The proof is an application of a version of the Nash-Moser implicit function theorem.

Print ISSN: 0033-5606

Digitale ISSN: 1464-3847

Thema: Mathematik

Publiziert von Oxford University Press

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Examples of noncompact nonpositively curved manifolds (2021)

Avramidi, Grigori ; Nguyễn‐Phan, T. Tâm

Oxford University Press

In: Bulletin of the London Mathematical Society. 2021; blms.12484. Published 2021 Mar 06. doi: 10.1112/blms.12484. [early online release]

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Publikationsdatum: 2021-03-06

Print ISSN: 0024-6093

Digitale ISSN: 1469-2120

Thema: Mathematik

Publiziert von Oxford University Press

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A composite framework for supporting user emotion detection based on intelligent taxonomy handling (2021)

Cuzzocrea, Alfredo ; Pilato, Giovanni

Oxford University Press

In: Logic Journal of the IGPL. 2021; Published 2021 Feb 16. doi: 10.1093/jigpal/jzaa047. [early online release]

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Publikationsdatum: 2021-02-16

Beschreibung: One of the most relevant issues of a social robot is its capability of catching the attention of a new acquaintance and empathize with her. The first steps towards a system which can be used by a social robot in order to be empathetic are illustrated in this paper. The system can analyze the Twitter ID of the new acquaintance, trying to detect the IAB (Interactive Advertising Bureau) Tier 1 categories that possibly can let arise in him/her a joyful feeling. Furthermore, it can retrieve news about that category and report them to the user, hopefully increasing his/her curiosity towards the system, improving the naturalness of the interaction. Moreover, the system is capable of querying Wikipedia in order to clarify any doubts that may arise in the user. A sample of a possible interaction is reported at the end of the paper.

Print ISSN: 1367-0751

Digitale ISSN: 1368-9894

Thema: Mathematik

Publiziert von Oxford University Press

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Improved lower bounds for the number of fields with alternating Galois group (2021)

Landesman, Aaron ; Lemke Oliver, Robert J. ; Thorne, Frank

Oxford University Press

In: Bulletin of the London Mathematical Society. 2021; blms.12490. Published 2021 Apr 19. doi: 10.1112/blms.12490. [early online release]

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Publikationsdatum: 2021-04-19

Print ISSN: 0024-6093

Digitale ISSN: 1469-2120

Thema: Mathematik

Publiziert von Oxford University Press

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Multiscale substitution tilings (2021)

Smilansky, Yotam ; Solomon, Yaar

Oxford University Press

In: Proceedings of the London Mathematical Society. 2021; plms.12404. Published 2021 Apr 19. doi: 10.1112/plms.12404. [early online release]

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Publikationsdatum: 2021-04-19

Print ISSN: 0024-6115

Digitale ISSN: 1460-244X

Thema: Mathematik

Publiziert von Oxford University Press

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On Eagleson's theorem in the non‐stationary setup (2021)

Hafouta, Yeor

Oxford University Press

In: Bulletin of the London Mathematical Society. 2021; blms.12477. Published 2021 Feb 27. doi: 10.1112/blms.12477. [early online release]

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Publikationsdatum: 2021-02-27

Print ISSN: 0024-6093

Digitale ISSN: 1469-2120

Thema: Mathematik

Publiziert von Oxford University Press

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A Minimum Aberration Type Criterion for Selecting Space-Filling Designs (2021)

Tian, Ye ; Xu, Hongquan

Oxford University Press

In: Biometrika. 2021; Published 2021 Mar 30. doi: 10.1093/biomet/asab021. [early online release]

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Publikationsdatum: 2021-03-30

Beschreibung: Space-filling designs are widely used in computer experiments. Inspired by the stratified orthogonality of strong orthogonal arrays, we propose a minimum aberration type criterion for assessing the space-filling properties of designs based on design stratification properties on various grids. A space-filling hierarchy principle is proposed as a basic assumption of the criterion. The new criterion provides a systematic way of classifying and ranking space-filling designs including various types of strong orthogonal arrays and Latin hypercube designs. Theoretical results and examples are presented to show that strong orthogonal arrays of maximum strength are favorable under the proposed criterion. For strong orthogonal arrays with the same strength, the space-filling criterion can further rank them based on their space-filling patterns.

Print ISSN: 0006-3444

Digitale ISSN: 1464-3510

Thema: Biologie , Mathematik , Medizin

Publiziert von Oxford University Press

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Wolff–Denjoy theorems in geodesic spaces (2021)

Huczek, A. ; Wiśnicki, A.

Oxford University Press

In: Bulletin of the London Mathematical Society. 2021; blms.12489. Published 2021 Apr 13. doi: 10.1112/blms.12489. [early online release]

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Publikationsdatum: 2021-04-13

Print ISSN: 0024-6093

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Thema: Mathematik

Publiziert von Oxford University Press

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Strongly self‐absorbing C∗‐algebras and Fraïssé limits (2021)

Ghasemi, Saeed

Oxford University Press

In: Bulletin of the London Mathematical Society. 2021; blms.12474. Published 2021 Feb 24. doi: 10.1112/blms.12474. [early online release]

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Publikationsdatum: 2021-02-24

Print ISSN: 0024-6093

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Thema: Mathematik

Publiziert von Oxford University Press

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Every 7‐Dimensional abelian variety over Qp has a reducible ℓ‐adic Galois representation (2021)

A'Campo, Lambert

Oxford University Press

In: Bulletin of the London Mathematical Society. 2021; blms.12472. Published 2021 Feb 25. doi: 10.1112/blms.12472. [early online release]

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Publikationsdatum: 2021-02-25

Print ISSN: 0024-6093

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Thema: Mathematik

Publiziert von Oxford University Press

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Radon measures and Lipschitz graphs (2021)

Badger, Matthew ; Naples, Lisa

Oxford University Press

In: Bulletin of the London Mathematical Society. 2021; blms.12473. Published 2021 Feb 23. doi: 10.1112/blms.12473. [early online release]

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Publikationsdatum: 2021-02-23

Print ISSN: 0024-6093

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Thema: Mathematik

Publiziert von Oxford University Press

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Corrigendum: Pseudo‐loop conditions (2021)

Gillibert, Pierre ; Jonušas, Julius ; Pinsker, Michael

Oxford University Press

In: Bulletin of the London Mathematical Society. 2021; blms.12471. Published 2021 Feb 25. doi: 10.1112/blms.12471. [early online release]

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Publikationsdatum: 2021-02-25

Print ISSN: 0024-6093

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Thema: Mathematik

Publiziert von Oxford University Press

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Sign non‐reversal property for totally non‐negative and totally positive matrices, and testing total positivity of their interval hull (2021)

Choudhury, Projesh Nath ; Kannan, M. Rajesh ; Khare, Apoorva

Oxford University Press

In: Bulletin of the London Mathematical Society. 2021; blms.12475. Published 2021 Feb 25. doi: 10.1112/blms.12475. [early online release]

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Publikationsdatum: 2021-02-25

Print ISSN: 0024-6093

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Thema: Mathematik

Publiziert von Oxford University Press

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Procurement modes for emergency supplies in the presence of disaster and commercial demands (2021)

Sun, Xiaochen ; Zhang, Jinghui ; Hu, Wei

Oxford University Press

In: IMA Journal of Management Mathematics. 2021; Published 2021 Apr 05. doi: 10.1093/imaman/dpab003. [early online release]

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Publikationsdatum: 2021-04-05

Beschreibung: This paper studies alternative procurement modes for emergency supplies in the presence of a public sector and a private supplier. A key feature of such a supply chain is that the private supplier must consider commercial demand in addition to disaster demand. Three procurement modes are analysed: an option mode (OM), an order-before-disaster mode (OBDM) and a procurement-after-disaster mode (PADM). We provide the optimal decisions associated with these three modes. Theoretical results in the OM show that a large order is not always better for the private supplier. From theoretical and numerical comparative analyses, no mode is absolutely superior. For the public sector, there are two thresholds. When the disaster probability is less than the low threshold, the revenues of all procurement modes are the same; when the disaster probability is larger than the high threshold, the OBDM has the highest revenue; otherwise, the OM has the highest revenue. However, for the private supplier, the PADM always has the highest revenue.

Print ISSN: 1471-678X

Digitale ISSN: 1471-6798

Thema: Mathematik

Publiziert von Oxford University Press im Namen von Institute of Mathematics and its Applications.

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Regularity for the two‐phase singular perturbation problems (2021)

Karakhanyan, Aram

Oxford University Press

In: Proceedings of the London Mathematical Society. 2021; plms.12402. Published 2021 Apr 06. doi: 10.1112/plms.12402. [early online release]

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Publikationsdatum: 2021-04-06

Print ISSN: 0024-6115

Digitale ISSN: 1460-244X

Thema: Mathematik

Publiziert von Oxford University Press

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Electron transfer in LiMn1.5Ni0.5O4 during charging studied with soft X-ray spectrometry (2021)

Okamoto, Ryosuke ; Terauchi, Masami

Oxford University Press

In: Microscopy. 2021; Published 2021 Apr 02. doi: 10.1093/jmicro/dfab014. [early online release]

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Publikationsdatum: 2021-04-02

Beschreibung: This is the first report on analyzing the chemical state of Li-ion battery electrodes at different states of charge by using a wavelength-dispersive spectrometer, which has a two-order improved energy resolution in the soft X-ray energy region compared with that of a conventional energy-dispersive X-ray analyzer. Electrodes containing LiMn1.5Ni0.5O4 were charged to prepare Li0.5Mn1.5Ni0.5O4 and λ-Mn0.75Ni0.25O2. The soft X-ray emission spectra obtained from those materials show that the O-K emission signal was drastically decreased throughout the charging process. This suggests that O-2p electron contributed to the electrochemical oxidation. The density of states and Bader charge evaluated from ab initio calculation support this result.

Print ISSN: 2050-5698

Digitale ISSN: 2050-5701

Thema: Elektrotechnik, Elektronik, Nachrichtentechnik , Allgemeine Naturwissenschaft , Physik

Publiziert von Oxford University Press im Namen von Japanese Society of Microscopy.

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A compound deep learning model for long range forecasting in electricity sale. (2021)

Tang, Tao ; Zhang, Yeqing ; Feng, Wenjiang

Oxford University Press

In: International Journal of Low Carbon Technologies. 2021; Published 2021 Apr 21. doi: 10.1093/ijlct/ctab028. [early online release]

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Publikationsdatum: 2021-04-21

Beschreibung: Accurate prediction of electricity sale has a positive effect on power companies in rationally arranging power supply plans, scientifically optimizing power resource allocation, improving power management efficiency, saving energy and reducing consumption. Predicting future electricity sale based on historical electricity sale data can essentially be summarized as a time series forecasting problem. This paper proposes a fast and memory-efficient method, which adopts the expressive power of deep neural networks and the time characteristics of sequence-to-sequence structure (parallel convolution and recurrent neural network) for long range forecasting in electricity sale. Through a large number of experiments and evaluation of real-world datasets, the effectiveness of the proposed method is proved and verified in terms of prediction accuracy, time consuming and training speed.

Print ISSN: 1748-1317

Digitale ISSN: 1748-1325

Thema: Energietechnik , Maschinenbau

Publiziert von Oxford University Press

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Uniform labelled calculi for preferential conditional logics based on neighbourhood semantics (2021)

Girlando, Marianna ; Negri, Sara ; Olivetti, Nicola

Oxford University Press

In: Journal of Logic and Computation. 2021; Published 2021 Apr 09. doi: 10.1093/logcom/exab019. [early online release]

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Publikationsdatum: 2021-04-09

Beschreibung: The preferential conditional logic $ mathbb{PCL} $, introduced by Burgess, and its extensions are studied. First, a natural semantics based on neighbourhood models, which generalizes Lewis’ sphere models for counterfactual logics, is proposed. Soundness and completeness of $ mathbb{PCL} $ and its extensions with respect to this class of models are proved directly. Labelled sequent calculi for all logics of the family are then introduced. The calculi are modular and have standard proof-theoretical properties, the most important of which is admissibility of cut that entails a syntactic proof of completeness of the calculi. By adopting a general strategy, root-first proof search terminates, thereby providing a decision procedure for $ mathbb{PCL} $ and its extensions. Finally, semantic completeness of the calculi is established: from a finite branch in a failed proof attempt it is possible to extract a finite countermodel of the root sequent. The latter result gives a constructive proof of the finite model property of all the logics considered.

Print ISSN: 0955-792X

Digitale ISSN: 1465-363X

Thema: Informatik , Mathematik

Publiziert von Oxford University Press

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A dual approach to Burkholder's Lp estimates (2021)

Bañuelos, Rodrigo ; Gałązka, Tomasz ; Osękowski, Adam

Oxford University Press

In: Bulletin of the London Mathematical Society. 2021; blms.12487. Published 2021 Apr 01. doi: 10.1112/blms.12487. [early online release]

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Publikationsdatum: 2021-04-01

Print ISSN: 0024-6093

Digitale ISSN: 1469-2120

Thema: Mathematik

Publiziert von Oxford University Press

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Bending laminations on convex hulls of anti‐de Sitter quasi‐circles (2021)

Merlin, Louis ; Schlenker, Jean‐Marc

Oxford University Press

In: Proceedings of the London Mathematical Society. 2021; plms.12401. Published 2021 Apr 08. doi: 10.1112/plms.12401. [early online release]

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Publikationsdatum: 2021-04-08

Print ISSN: 0024-6115

Digitale ISSN: 1460-244X

Thema: Mathematik

Publiziert von Oxford University Press

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A posteriori error estimation and space-time adaptivity for a linear stochastic PDE with additive noise (2021)

Majee, Ananta K ; Prohl, Andreas

Oxford University Press

In: IMA Journal of Numerical Analysis. 2021; Published 2021 Mar 25. doi: 10.1093/imanum/drab013. [early online release]

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Publikationsdatum: 2021-03-25

Beschreibung: We present a strong residual-based a posteriori error estimate for a finite element-based space-time discretization of the linear stochastic convected heat equation with additive noise. This error estimate is used for an adaptive algorithm that automatically selects deterministic mesh parameters in space and time. For every $n geq 0$, we find a new time-step $au _n$, a new spatial mesh ${mathcal M}_{n}$ terminating within finitely many iterations and a finite element value approximation $Y^n_h$ on this spatial mesh, which then approximates strongly the solution of the stochastic partial differential equation (SPDE) within a prescribed tolerance.

Print ISSN: 0272-4979

Digitale ISSN: 1464-3642

Thema: Mathematik

Publiziert von Oxford University Press im Namen von Institute of Mathematics and its Applications.

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Operando observation of magnetism in HDD writing heads by spin-polarized scanning electron microscopy (2021)

Kohashi, Teruo ; Motai, Kumi ; Matsuyama, Hideo ; [weitere]

Oxford University Press

In: Microscopy. 2021; Published 2021 Mar 04. doi: 10.1093/jmicro/dfab011. [early online release]

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Publikationsdatum: 2021-03-04

Beschreibung: Operando observation using spin-polarized scanning electron microscopy (spin SEM) has been demonstrated by detecting changes in the magnetization in the writing head of a hard disk drive (HDD) during operation. A current-applying system developed for use in the sample stage of a spin SEM enables imaging of the magnetization changes in the writing head of an HDD while the writing head is activated. Focused ion beam (FIB) technology is used to fabricate electric contacts between the head terminals and the sample holder electrodes. Tungsten film is deposited by FIB technology on the insulator around the writing head to prevent electrostatic charge buildup in the insulators during SEM measurement. This system is well suited for studying the characteristics of writing heads in HDDs in an activated state.

Print ISSN: 2050-5698

Digitale ISSN: 2050-5701

Thema: Elektrotechnik, Elektronik, Nachrichtentechnik , Allgemeine Naturwissenschaft , Physik

Publiziert von Oxford University Press im Namen von Japanese Society of Microscopy.

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Corrigendum to: Frame definability, canonicity and cut elimination in common sense modal predicate logics (2021)

Sawasaki, Takahiro ; Sano, Katsuhiko

Oxford University Press

In: Journal of Logic and Computation. 2021; Published 2021 Apr 21. doi: 10.1093/logcom/exab031. [early online release]

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Publikationsdatum: 2021-04-21

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Thema: Informatik , Mathematik

Publiziert von Oxford University Press

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Modeling Hessian-vector products in nonlinear optimization: new Hessian-free methods (2021)

Song, L ; Vicente, L N

Oxford University Press

In: IMA Journal of Numerical Analysis. 2021; Published 2021 Apr 06. doi: 10.1093/imanum/drab022. [early online release]

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Publikationsdatum: 2021-04-06

Beschreibung: In this paper we suggest two ways of calculating interpolation models for unconstrained smooth nonlinear optimization when Hessian-vector products are available. The main idea is to interpolate the objective function using a quadratic on a set of points around the current one, and concurrently using the curvature information from products of the Hessian times appropriate vectors, possibly defined by the interpolating points. These enriched interpolating conditions then form an affine space of model Hessians or model Newton directions, from which a particular one can be computed once an equilibrium or least secant principle is defined. A first approach consists of recovering the Hessian matrix satisfying the enriched interpolating conditions, from which then a Newton direction model can be computed. In a second approach we pose the recovery problem directly in the Newton direction. These techniques can lead to a significant reduction in the overall number of Hessian-vector products when compared to the inexact or truncated Newton method, although simple implementations may pay a cost in the number of function evaluations and the dense linear algebra involved poses a scalability challenge.

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Digitale ISSN: 1464-3642

Thema: Mathematik

Publiziert von Oxford University Press im Namen von Institute of Mathematics and its Applications.

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More for less: predicting and maximizing genomic variant discovery via Bayesian nonparametrics (2021)

Masoero, Lorenzo ; Camerlenghi, Federico ; Favaro, Stefano ; [weitere]

Oxford University Press

In: Biometrika. 2021; Published 2021 Feb 23. doi: 10.1093/biomet/asab012. [early online release]

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Publikationsdatum: 2021-02-23

Beschreibung: While the cost of sequencing genomes has decreased dramatically in recent years, this expense often remains non-trivial. Under a fixed budget, scientists face a natural trade-off between quantity and quality: spending resources to sequence a greater number of genomes or spending resources to sequence genomes with increased accuracy. Our goal is to find the optimal allocation of resources between quantity and quality. Optimizing resource allocation promises to reveal as many new variations in the genome as possible. In this paper, we introduce a Bayesian nonparametric methodology to predict the number of new variants in a follow-up study based on a pilot study. When experimental conditions are kept constant between the pilot and follow-up, we find that our prediction is competitive with the best existing methods. Unlike current methods, though, our new method allows practitioners to change experimental conditions between the pilot and the follow-up. We demonstrate how this distinction allows our method to be used for more realistic predictions and for optimal allocation of a fixed budget between quality and quantity.

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Digitale ISSN: 1464-3510

Thema: Biologie , Mathematik , Medizin

Publiziert von Oxford University Press

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Semirings of Evidence (2021)

Baur, Michael ; Studer, Thomas

Oxford University Press

In: Journal of Logic and Computation. 2021; Published 2021 Feb 24. doi: 10.1093/logcom/exab007. [early online release]

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Publikationsdatum: 2021-02-24

Beschreibung: In traditional justification logic, evidence terms have the syntactic form of polynomials, but they are not equipped with the corresponding algebraic structure. We present a novel semantic approach to justification logic that models evidence by a semiring. Hence justification terms can be interpreted as polynomial functions on that semiring. This provides an adequate semantics for evidence terms and clarifies the role of variables in justification logic. Moreover, the algebraic structure makes it possible to compute with evidence. Depending on the chosen semiring this can be used to model trust, probabilities, cost, etc. Last but not least the semiring approach seems promising for obtaining a realization procedure for modal fixed point logics.

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Thema: Informatik , Mathematik

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Cosine polynomials with few zeros (2021)

Juškevičius, Tomas ; Sahasrabudhe, Julian

Oxford University Press

In: Bulletin of the London Mathematical Society. 2021; blms.12468. Published 2021 Feb 03. doi: 10.1112/blms.12468. [early online release]

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Publikationsdatum: 2021-02-03

Print ISSN: 0024-6093

Digitale ISSN: 1469-2120

Thema: Mathematik

Publiziert von Oxford University Press

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Every bounded pseudo‐convex domain with Hölder boundary is hyperconvex (2021)

Chen, Bo‐Yong

Oxford University Press

In: Bulletin of the London Mathematical Society. 2021; blms.12478. Published 2021 Feb 26. doi: 10.1112/blms.12478. [early online release]

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Publikationsdatum: 2021-02-26

Print ISSN: 0024-6093

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Thema: Mathematik

Publiziert von Oxford University Press

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Labelled calculi for quantified modal logics with definite descriptions (2021)

Orlandelli, Eugenio

Oxford University Press

In: Journal of Logic and Computation. 2021; Published 2021 Apr 14. doi: 10.1093/logcom/exab018. [early online release]

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Publikationsdatum: 2021-04-14

Beschreibung: We introduce labelled sequent calculi for quantified modal logics with definite descriptions. We prove that these calculi have the good structural properties of G3-style calculi. In particular, all rules are height-preserving invertible, weakening and contraction are height-preserving admissible and cut is syntactically admissible. Finally, we show that each calculus gives a proof-theoretic characterization of validity in the corresponding class of models.

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Thema: Informatik , Mathematik

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Non-uniform ISS small-gain theorem for infinite networks (2021)

Mironchenko, Andrii

Oxford University Press

In: IMA Journal of Mathematical Control and Information. 2021; Published 2021 Aug 09. doi: 10.1093/imamci/dnab026. [early online release]

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Publikationsdatum: 2021-08-09

Beschreibung: We introduce the concept of non-uniform input-to-state stability for networks. It combines the uniform global stability with the uniform attractivity of any subnetwork while it allows for non-uniform convergence of all components. For an infinite network consisting of input-to-state stable subsystems, which do not necessarily have a uniform $mathscr{K}mathscr{L}$-bound on the transient behaviour, we show the following: if the gain operator satisfies the uniform small-gain condition, then the whole network is non-uniformly input-to-state stable and all its finite subnetworks are input-to-state stable.

Print ISSN: 0265-0754

Digitale ISSN: 1471-6887

Thema: Mathematik

Publiziert von Oxford University Press im Namen von Institute of Mathematics and its Applications.

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A two-stage method for improving discrimination and variable selection in DEA models (2021)

Xie, Qiwei ; Li, Rong ; Zou, Yanping ; [weitere]

Oxford University Press

In: IMA Journal of Management Mathematics. 2021; Published 2021 Aug 12. doi: 10.1093/imaman/dpab023. [early online release]

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Publikationsdatum: 2021-08-12

Beschreibung: One of the main challenges when applying data envelopment analysis (DEA) is the selection of appropriate input and output variables. This paper addresses this important problem using a novel two-stage method. In the first stage, we use entropy theory to generate a comprehensive efficiency score (CES) of each decision-making unit. In the second stage, we select input and output variables using the Bayesian information criterion, when CES is treated as a dependent variable and the input and output variables are used as explanatory variables. We use stochastic data to demonstrate that our proposed method can improve the discrimination power of DEA and determine the important input and output variables. Finally, we compare the proposed method with principal component analysis using datasets on carbon emissions in China. This comparison demonstrates the practical value of our proposed method.

Print ISSN: 1471-678X

Digitale ISSN: 1471-6798

Thema: Mathematik

Publiziert von Oxford University Press im Namen von Institute of Mathematics and its Applications.

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Currents, systoles, and compactifications of character varieties (2021)

Burger, M. ; Iozzi, A. ; Parreau, A. ; [weitere]

Oxford University Press

In: Proceedings of the London Mathematical Society. 2021; plms.12419. Published 2021 Aug 10. doi: 10.1112/plms.12419. [early online release]

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Publikationsdatum: 2021-08-10

Print ISSN: 0024-6115

Digitale ISSN: 1460-244X

Thema: Mathematik

Publiziert von Oxford University Press

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In This Issue (2021)

Oxford University Press

In: Microscopy. 2021; 70(4): 1-4. Published 2021 Aug 01. doi: 10.1093/jmicro/dfab024.

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Publikationsdatum: 2021-08-01

Print ISSN: 2050-5698

Digitale ISSN: 2050-5701

Thema: Elektrotechnik, Elektronik, Nachrichtentechnik , Allgemeine Naturwissenschaft , Physik

Publiziert von Oxford University Press im Namen von Japanese Society of Microscopy.

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Blurrings Of The J-Function (2021)

Aslanyan, Vahagn ; Kirby, Jonathan

Oxford University Press

In: Quarterly Journal of Mathematics. 2021; Published 2021 Aug 14. doi: 10.1093/qmath/haab037. [early online release]

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Publikationsdatum: 2021-08-14

Beschreibung: Inspired by the idea of blurring the exponential function, we define blurred variants of the j-function and its derivatives, where blurring is given by the action of a subgroup of $mathrm{GL}_2({mathbb{C}})$. For a dense subgroup (in the complex topology) we prove an Existential Closedness theorem which states that all systems of equations in terms of the corresponding blurred j with derivatives have complex solutions, except where there is a functional transcendence reason why they should not. For the j-function without derivatives we prove a stronger theorem, namely, Existential Closedness for j blurred by the action of a subgroup which is dense in $mathrm{GL}_2^+(mathbb{R})$, but not necessarily in $mathrm{GL}_2({mathbb{C}})$. We also show that for a suitably chosen countable algebraically closed subfield $C subseteq {mathbb{C}}$, the complex field augmented with a predicate for the blurring of the j-function by $mathrm{GL}_2(C)$ is model theoretically tame, in particular, ω-stable and quasiminimal.

Print ISSN: 0033-5606

Digitale ISSN: 1464-3847

Thema: Mathematik

Publiziert von Oxford University Press

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An HDG method for dissimilar meshes (2021)

Solano, Manuel ; Terrana, Sébastien ; Nguyen, Ngoc-Cuong ; [weitere]

Oxford University Press

In: IMA Journal of Numerical Analysis. 2021; Published 2021 Aug 13. doi: 10.1093/imanum/drab059. [early online release]

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Publikationsdatum: 2021-08-13

Beschreibung: We present a hybridizable discontinuous Galerkin (HDG) method for dissimilar meshes. The method is devised by formulating HDG discretizations on separate meshes and gluing these HDG discretizations through appropriate transmission conditions that weakly enforce the continuity of the numerical trace and the numerical flux across the dissimilar interfaces. The transmission conditions are based upon transferring the numerical flux from the first mesh to the second mesh and the numerical trace from the second mesh to the first one. The transfer of the numerical trace/flux from one mesh to the other relies on the extrapolation of the approximate flux, and is made to be consistent with the HDG methodology for conforming meshes. Stability of the HDG method is shown and the error analysis of the HDG method is established. Numerical results are presented to validate the theoretical results.

Print ISSN: 0272-4979

Digitale ISSN: 1464-3642

Thema: Mathematik

Publiziert von Oxford University Press im Namen von Institute of Mathematics and its Applications.

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Optimal portfolio execution with a Markov chain approximation approach (2021)

Chen, Jingnan ; Feng, Liming ; Peng, Jiming ; [weitere]

Oxford University Press

In: IMA Journal of Management Mathematics. 2021; Published 2021 Aug 16. doi: 10.1093/imaman/dpab025. [early online release]

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Publikationsdatum: 2021-08-16

Beschreibung: We study the problem of executing a large multi-asset portfolio in a short time period where the objective is to find an optimal trading strategy that minimizes both the trading cost and the trading risk measured by quadratic variation. We contribute to the existing literature by considering a multi-dimensional geometric Brownian motion model for asset prices and proposing an efficient Markov chain approximation (MCA) approach to obtain the optimal trading trajectory. The MCA approach allows us not only to numerically compute the optimal strategy but also to theoretically analyse the influence of factors such as price impact, risk aversion and initial asset price on the optimal strategy, providing both quantitative and qualitative guidance on the trading behaviour. Numerical results verify the theoretical conclusions in the paper. They further illustrate the effects of cross impact and correlations on the optimal execution strategy in a multi-asset liquidation problem.

Print ISSN: 1471-678X

Digitale ISSN: 1471-6798

Thema: Mathematik

Publiziert von Oxford University Press im Namen von Institute of Mathematics and its Applications.

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Asymptotics for 2D whispering gallery modes in optical micro-disks with radially varying index (2021)

Balac, Stéphane ; Dauge, Monique ; Moitier, Zoïs

Oxford University Press

In: IMA Journal of Applied Mathematics. 2021; Published 2021 Aug 10. doi: 10.1093/imamat/hxab033. [early online release]

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Publikationsdatum: 2021-08-10

Beschreibung: Whispering gallery modes [WGM] are resonant modes displaying special features: they concentrate along the boundary of the optical cavity at high polar frequencies and they are associated with complex scattering resonances very close to the real axis. As a classical simplification of the full Maxwell system, we consider 2D Helmholtz equations governing transverse electric or magnetic modes. Even in this 2D framework, very few results provide asymptotic expansion of WGM resonances at high polar frequency $mo infty $ for cavities with radially varying optical index. In this work, using a direct Schrödinger analogy, we highlight three typical behaviors in such optical micro-disks, depending on the sign of an ‘effective curvature’ that takes into account the radius of the disk and the values of the optical index and its derivative. Accordingly, this corresponds to abruptly varying effective potentials (step linear or step harmonic) or more classical harmonic potentials, leading to three distinct asymptotic expansions for ground state energies. Using multiscale expansions, we design a unified procedure to construct families of quasi-resonances and associate quasi-modes that have the WGM structure and satisfy eigenequations modulo a super-algebraically small residual ${mathscr{O}}(m^{-infty })$. We show using the black box scattering approach that quasi-resonances are ${mathscr{O}}(m^{-infty })$ close to true resonances.

Print ISSN: 0272-4960

Digitale ISSN: 1464-3634

Thema: Mathematik

Publiziert von Oxford University Press im Namen von Institute of Mathematics and its Applications.

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Discussion of ‘Estimating time-varying causal excursion effects in mobile health with binary outcomes’ (2021)

Guo, F Richard ; Richardson, Thomas S ; Robins, James M

Oxford University Press

In: Biometrika. 2021; 108(3): 541-550. Published 2021 Aug 12. doi: 10.1093/biomet/asab029.

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Publikationsdatum: 2021-08-12

Print ISSN: 0006-3444

Digitale ISSN: 1464-3510

Thema: Biologie , Mathematik , Medizin

Publiziert von Oxford University Press

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Realizations and orientation of implicit systems (2021)

Vafiadis, Dimitris

Oxford University Press

In: IMA Journal of Mathematical Control and Information. 2021; Published 2021 Aug 07. doi: 10.1093/imamci/dnab025. [early online release]

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Publikationsdatum: 2021-08-07

Beschreibung: The paper considers the problem of model orientation, i.e. the classification of the external signals into inputs and outputs. The problem is considered in the behavioural context where the external model is an autoregressive system. Orientation of a system automatically induces equivalent first order models in state–space or descriptor form via a realization procedure. A new realization procedure is proposed where the realization is implemented in two steps, first an intermediate ARMA realization is obtained. Then, this realization is transformed into the final descriptor system via an appropriate reduction procedure corresponding to the input/output partition of the external variables. Studying the dependency of the resulting system properties and invariants on the different selections of input and output variables and the structure of the initial external behaviour is considered in the paper.

Print ISSN: 0265-0754

Digitale ISSN: 1471-6887

Thema: Mathematik

Publiziert von Oxford University Press im Namen von Institute of Mathematics and its Applications.

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Rejoinder: ‘Estimating time-varying causal excursion effects in mobile health with binary outcomes’ (2021)

Qian, Tianchen ; Yoo, Hyesun ; Klasnja, Predrag ; [weitere]

Oxford University Press

In: Biometrika. 2021; 108(3): 551-555. Published 2021 Aug 12. doi: 10.1093/biomet/asab033.

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Publikationsdatum: 2021-08-12

Print ISSN: 0006-3444

Digitale ISSN: 1464-3510

Thema: Biologie , Mathematik , Medizin

Publiziert von Oxford University Press

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Stabilization of a class of switched dynamic systems: the Riccati-equation-based Approach (2021)

Bonilla, M ; Aguillón,, N A ; Ortiz Castillo, M A ; [weitere]

Oxford University Press

In: IMA Journal of Mathematical Control and Information. 2021; Published 2021 Aug 13. doi: 10.1093/imamci/dnab022. [early online release]

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Publikationsdatum: 2021-08-13

Beschreibung: Our paper deals with the stabilization of a class of time-dependent linear autonomous complex systems with a switched structure. The initially given switched dynamic system is assumed to be controlled by a specific state feedback strategy associated with the linear quadratic regulator (LQR) type control. The proposed control design guarantees stabilization of the closed-loop system for all of the possible location transitions. In the solution procedure of the Algebraic Riccati Equation related to the LQR control strategy, only the knowledge of the algebraic structure related to the switched system are needed. We prove that the proposed optimal LQR type state feedback control design stabilizes the closed-loop switched system for every possible active location. The theoretical approach proposed in this paper is finally applied to a model of the Single Wing Quadrotor Aircraft, when changing from its Quadrotor Flight Envelope to its Airplane Flight Envelope.

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Thema: Mathematik

Publiziert von Oxford University Press im Namen von Institute of Mathematics and its Applications.

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On the convergence and mesh-independent property of the Barzilai–Borwein method for PDE-constrained optimization (2021)

Azmi, Behzad ; Kunisch, Karl

Oxford University Press

In: IMA Journal of Numerical Analysis. 2021; Published 2021 Aug 05. doi: 10.1093/imanum/drab056. [early online release]

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Publikationsdatum: 2021-08-05

Beschreibung: Aiming at optimization problems governed by partial differential equations (PDEs), local R-linear convergence of the Barzilai–Borwein (BB) method for a class of twice continuously Fréchet-differentiable functions is proven. Relying on this result, the mesh-independent principle for the BB-method is investigated. The applicability of the theoretical results is demonstrated for two different types of PDE-constrained optimization problems. Numerical experiments are given, which illustrate the theoretical results.

Print ISSN: 0272-4979

Digitale ISSN: 1464-3642

Thema: Mathematik

Publiziert von Oxford University Press im Namen von Institute of Mathematics and its Applications.

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Discussion of ‘Estimating time-varying causal excursion effects in mobile health with binary outcomes’ (2021)

Kim, S ; Cho, H ; Bang, D ; [weitere]

Oxford University Press

In: Biometrika. 2021; 108(3): 529-533. Published 2021 Aug 12. doi: 10.1093/biomet/asaa094.

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Publikationsdatum: 2021-08-12

Beschreibung: Summary In this discussion, we examine the contributions of Qian et al. (2021) and potential applications of the newly developed estimator for the causal excursion effect in binary outcome data. Specifically, we consider extension of their method to count outcomes and observational data, propose an alternative use of their method for analysing excursion effect trajectories and discuss ways of improving estimator efficiency.

Print ISSN: 0006-3444

Digitale ISSN: 1464-3510

Thema: Biologie , Mathematik , Medizin

Publiziert von Oxford University Press

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In situ observation of the chemical bonding state of Si in the molten state of eutectic Au–Si alloy of Au81Si19 by using a soft X-ray emission spectroscopy electron microscope (2021)

Terauchi, Masami ; Umemoto, Naoya ; K. Sato, Yohei ; [weitere]

Oxford University Press

In: Microscopy. 2021; Published 2021 Aug 06. doi: 10.1093/jmicro/dfab029. [early online release]

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Publikationsdatum: 2021-08-06

Beschreibung: Phase diagram of Au–Si binary alloy system shows a large drop in melting temperature of about 1000K compared with that of Si at a composition of Au:Si = 81:19, where the melting temperature is about 636K. Mixing of Au and Si below the melting temperature was observed by transmission electron microscopy experiment, and it was found that the mixed region shows a diffraction pattern of a diffuse ring intensity indicating an amorphous structure of the mixed area. Si L-emission spectra, which reflect the energy state of bonding electrons of Si atom, of molten Au81Si19 alloy were measured for the first time to investigate the energy state of valence electrons of Si. The Si L-emission spectrum showed a characteristic loss of L1 peak, which is related to sp3 directional bonding in crystalline Si. The intensity profile is also different from that of molten Si reported. This suggests a characteristic atomic arrangement that exists in the molten state. The intensity profile also indicated a small density of state in the molten state at Fermi energy. The obtained spectrum was compared with the calculated density of state of possible crystal structures reported. The comparison suggested that Si atoms are surrounded by eight Au atoms in the molten state of Au81Si19 alloy. The formation of this local atomic arrangement can be an origin of a large drop of melting temperature at about Au:Si = 81:19.

Print ISSN: 2050-5698

Digitale ISSN: 2050-5701

Thema: Elektrotechnik, Elektronik, Nachrichtentechnik , Allgemeine Naturwissenschaft , Physik

Publiziert von Oxford University Press im Namen von Japanese Society of Microscopy.

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Research on control strategy of multi-source data fusion solar intelligent vehicle based on image recognition (2021)

Zhang, Lulin

Oxford University Press

In: International Journal of Low Carbon Technologies. 2021; Published 2021 Aug 07. doi: 10.1093/ijlct/ctab057. [early online release]

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Publikationsdatum: 2021-08-07

Beschreibung: Nowadays, the global energy and environmental problems are becoming more and more serious, which promotes the development and utilization of renewable and clean energy in various countries. Intelligent car involves many subjects such as electronic technology, artificial intelligence, automatic control technology, sensor technology and computer technology and has become an important part of the application of artificial intelligence. Solar cell is a necessary part of the normal operation of the solar intelligent car, which can provide clean energy for the intelligent car. In this paper, the image recognition technology is used to design the intelligent vehicle control system. According to the intelligent vehicle path recognition, the scale invariant feature transform (SIFT) algorithm is improved to improve the accuracy of intelligent vehicle recognition. Data fusion is used to process the data detected by multi-sensor, and the running state of intelligent vehicle is studied. An evaluation method of intelligent vehicle navigation parameters based on association rules and belief network is proposed. The maximum power point tracking control is realized by using the interference observation method to ensure that the intelligent vehicle can track the maximum power point of the solar cell.

Print ISSN: 1748-1317

Digitale ISSN: 1748-1325

Thema: Energietechnik , Maschinenbau

Publiziert von Oxford University Press

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A high-order fully discrete scheme for the Korteweg–de Vries equation with a time-stepping procedure of Runge–Kutta-composition type (2021)

Dougalis, Vassilios A ; Durán, Ángel

Oxford University Press

In: IMA Journal of Numerical Analysis. 2021; Published 2021 Aug 12. doi: 10.1093/imanum/drab060. [early online release]

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Publikationsdatum: 2021-08-12

Beschreibung: We consider the periodic initial-value problem for the Korteweg–de Vries equation that we discretize in space by a spectral Fourier–Galerkin method and in time by an implicit, high-order, Runge–Kutta scheme of composition type based on the implicit midpoint rule. We prove $L^{2}$ error estimates for the resulting semidiscrete and the fully discrete approximations. Some numerical experiments illustrate the results.

Print ISSN: 0272-4979

Digitale ISSN: 1464-3642

Thema: Mathematik

Publiziert von Oxford University Press im Namen von Institute of Mathematics and its Applications.

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Forty years of score-based soccer match outcome prediction: an experimental review (2021)

Hubáček, Ondřej ; Šourek, Gustav ; železný, Filip

Oxford University Press

In: IMA Journal of Management Mathematics. 2021; Published 2021 Aug 06. doi: 10.1093/imaman/dpab029. [early online release]

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Publikationsdatum: 2021-08-06

Beschreibung: We investigate the state-of-the-art in score-based soccer match outcome modelling to identify the top-performing methods across diverse classes of existing approaches to the problem. Namely, we bring together various statistical methods based on Poisson and Weibull distributions and several general ranking algorithms (Elo, Steph ratings, Gaussian-OD ratings) as well as domain-specific rating systems (Berrar ratings, pi-ratings). We review, reimplement and experimentally compare these diverse competitors altogether on the largest database of soccer results available to identify true leaders. Our results reveal that the individual predictions, as well as the overall performances, are very similar across the top models tested, likely suggesting the limits of this generic approach to score-based match outcome modelling. No study of a similar scale has previously been done.

Print ISSN: 1471-678X

Digitale ISSN: 1471-6798

Thema: Mathematik

Publiziert von Oxford University Press im Namen von Institute of Mathematics and its Applications.

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Study on the heterogeneous material coupling connection characteristics and mechanical strength of Oratosquilla oratoria mantis shrimp saddle (2021)

Liang, Yunhong ; Zhang, Hao ; Zhao, Qian ; [weitere]

Oxford University Press

In: Microscopy. 2021; 70(4): 361-367. Published 2021 Jan 22. doi: 10.1093/jmicro/dfab004.

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Publikationsdatum: 2021-01-22

Beschreibung: The microstructure, chemical composition and mechanical strength of heterogeneous materials of mantis shrimp (Oratosquilla oratoria) saddle were studied. As the key component of the striking system, the saddle comprised two distinct layers including outer layer and inner layer. The outer layer contained blocky microtubules and exhibited compact appearance. The inner layer presented a typical periodic lamellar structure. Due to the change of the thickness of the mineralized outer layer, the organic multilamellar structure became the foundation and enhanced the connection strength (4.55 MPa) at the connect regions between the saddle and merus exoskeleton and membrane, respectively. In the process of fracture, the lamellar structure dispersed the stress effectively by the change of the crack deflection direction and the microfibrils ordered arrangement. The exploration of mantis shrimp saddle region is beneficial to understand the striking system and provided the possibility for the stable connection of heterogeneous materials in engineering fields. The microstructure, heterogeneous material connection characteristics and high mechanical strength of saddle provide bionic models for the preparation of fiber-reinforced resin composites and soft composites.

Print ISSN: 2050-5698

Digitale ISSN: 2050-5701

Thema: Elektrotechnik, Elektronik, Nachrichtentechnik , Allgemeine Naturwissenschaft , Physik

Publiziert von Oxford University Press im Namen von Japanese Society of Microscopy.

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A simple preparation method for CLEM using pre-embedding immunohistochemistry with a novel fluorescent probe and stable embedding resin (2021)

Kanemaru, Takaaki ; Kondo, Teruyoshi ; Nakamura, Kei-ichiro ; [weitere]

Oxford University Press

In: Microscopy. 2021; 70(4): 368-374. Published 2021 Jan 22. doi: 10.1093/jmicro/dfab005.

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Publikationsdatum: 2021-01-22

Beschreibung: Correlative light and electron microscopy (CLEM) is an excellent approach for examining the cellular localization of biomolecules. Here, we developed a simple method for CLEM by combining pre-embedding immunohistochemistry with a novel fluorescent probe, namely Fluolid NS Orange, and an embedding resin called ʻDurcupan™ʼ. Specimens were embedded in Durcupan™ or LR White after immunolabeling and post-fixation using glutaraldehyde and osmium tetroxide. Next, ultrathin sections were prepared on a finder grid with navigation markers. The section of the specimen embedded in Durcupan™ was found to be more stable against electron beam irradiation than specimens embedded in LR White. A fluorescence light microscopy image and a transmission electron microscopy (TEM) image, at wide-field, and low magnification, were independently obtained with the same ultrathin section. Using the three corners between finder grid bars as landmarks, fluorescence light microscopy images were superimposed with wide-field, low-magnification TEM images to identify the region of interest, which was subsequently enlarged to ascertain cellular structures localized beneath fluorescent signals. However, the enlarged TEM images appeared blurred, and fluorescence signals had a hazy appearance. To resolve this, the enlarged TEM images were replaced by high-resolution TEM images focused directly on the region of interest, thereby facilitating the collection of high-resolution CLEM images. The simple sample processing method for CLEM using osmium-resistant Fluolid NS Orange and electron beam damage-resistant Durcupan™ allowed the determination of the precise localization of fluorescence signals at subcellular levels.

Print ISSN: 2050-5698

Digitale ISSN: 2050-5701

Thema: Elektrotechnik, Elektronik, Nachrichtentechnik , Allgemeine Naturwissenschaft , Physik

Publiziert von Oxford University Press im Namen von Japanese Society of Microscopy.

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