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Dieser Beitrag gibt einen Überblick über die jüngsten Ergebnisse einer laufenden Pilotanwendung eines nichtlinearen MPC (Model Predictive Controller) für einen industriellen Polymerisationsprozess. Sowohl der MPC als auch der Soft-Sensor verwenden denselben digitalen Zwilling des verfahrenstechnischen Prozesses, ein dynamisches Fließschema-Modell hoher Genauigkeit, dasauf grundlegenden Bilanzgleichungen beruht und auch das Herzstück eines Schulungssystems für die Anlagenfahrer ist.

We introduce a new framework for solving an important class of computational problems involving finite permutation groups, which includes calculating set stabilisers, intersections of subgroups, and isomorphisms of combinatorial structures. Our techniques are inspired by and generalise 'partition backtrack', which is the current state-of-the-art algorithm introduced by Jeffrey Leon in 1991. But, instead of ordered partitions, we use labelled directed graphs to organise our backtrack search algorithms, which allows for a richer representation of many problems while often resulting in smaller search spaces. In this article we present the theory underpinning our framework, we describe our algorithms, and we show the results of some experiments. An implementation of our algorithms is available as free software in the GraphBacktracking package for GAP., Shorter and reworked version of arXiv:1911.04783; accepted for publication in Journal of Algebra; 35 pages, 9 figures, 4 tables

Purpose The results of a technique with a double reinsertion of the aponeurosis to the tarsus and aponeurosis to Whitnall’s ligament (ATW) were compared with a simple reinsertion of the aponeurosis to the tarsus (AT) in acquired aponeurotic palpebral ptosis surgery. Methods Analytical, observational, retrospective, cohort study. Seven hundred and twenty-two consecutive cases with acquired aponeurotic palpebral ptosis have been treated surgically between 2000 and 2012 and have been followed up for 5 years. The cases were divided into two cohorts according to the applied surgical technique (AT vs ATW). Results The mean postoperative MRD after 1 month in cohort AT was 1 mm lower than in ATW (3 ± 0.9 mm vs 4 ± 1 mm). The mean MRD in the long-term follow-up (5 years) was 1 mm lower in cohort AT than in ATW (2.9 ± 1.5 mm vs 3.9 ± 0.9 mm). The rate of long-term recurrence (5 years) was 15% higher in A-T than in A-T-W (20% vs 5%). 70.5% of the eyes studied intra-surgically presented gaps between the Whitnall ligament and the aponeurosis, an anatomical area that we describe as the upper transition zone (UTZ). In an independent analysis, only those patients with open UTZ were evaluated and it was observed that those operated with A-T-W presented elevations greater than 1 mm compared to those operated with the AT technique (4 ± 0.9 mm A-T-W vs 2.8 ± 1 mm A-T) and a much lower recurrence rate (5.4% A-T vs 38.09% A-T-W). Conclusions In our study, the A-T-W technique achieved better results in terms of palpebral elevation and fewer recurrences compared to the A-T technique in all cases studied with aponeurotic ptosis. However, it particularly demonstrates its superiority in patients with large gaps in the UTZ.

Model Predictive Control (MPC) is established as the most powerful and most successful method for multivariable control in the process industries. Most industrial applications of MPC rely on linear dynamic process models that are identified from active experiments on the plant. If a rigorous mechanistic model of the respective process unit already exists, it would be attractive to use this model directly inside an MPC algorithm. The PSE software “gPROMS Nonlinear Model Predictive Controller” (gNLMPC) provides precisely this functionality, and this paper describes its application to a polymerization reactor. Properties, features and advantages of linear and nonlinear MPC are compared systematically.

Der Artikel beschreibt ein Konzept für die Entwicklung und durchgängige Nutzung eines Digital Twins über den gesamten Lebenszyklus einer Prozessanlage. Dabei werden zuerst verschiedene Aspekte und Sichtweisen des Digital Twins definiert und erläutert. Die Möglichkeiten und der Nutzen für die verschiedenen Phasen des Lebenszyklus werden ausführlich dargestellt. Als praktisches Anwendungsbeispiel dient ein Steam Cracker zur Ethylenherstellung, für den das Konzept in Form eines Demonstrators realisiert ist.

Thin-film organic–inorganic hybrid perovskite (MeNH3PbI3) solar cells have displayed remarkably high photoconversion efficiencies, making their net-shaping as flexible device elements desirable for...

It is undecidable in general whether a given finitely presented group is word hyperbolic. We use the concept of pregroups, introduced by Stallings, to define a new class of van Kampen diagrams, which represent groups as quotients of virtually free groups. We then present a polynomial-time procedure which analyses these diagrams, and either returns an explicit linear Dehn function for the presentation, or returns fail, together with its reasons for failure. Furthermore, if our procedure succeeds we are often able to produce in polynomial time a word problem solver for the presentation that runs in linear time. Our algorithms have been implemented, and are often many orders of magnitude faster than KBMAG, the only comparable publicly available software., Comment: To appear in Journal of Symbolic Computation

Plasmonic nanoantennas allow for enhancing the spontaneous emission, altering the emission polarization, and shaping the radiation pattern of quantum emitters. A critical challenge for the experimental realizations is positioning a single emitter into the hotspot of a plasmonic antenna with nanoscale accuracy. We demonstrate a dynamic light-matter interaction nanosystem enabled by the DNA origami technique. A single fluorophore molecule can autonomously and unidirectionally walk into the hotspot of a plasmonic nanoantenna along a designated origami track. Successive fluorescence intensity increase and lifetime reduction are in situ monitored using single-molecule fluorescence spectroscopy, while the fluorophore walker gradually approaches and eventually enters the plasmonic hotspot. Our scheme offers a dynamic platform, which can be used to develop functional materials, investigate intriguing light-matter interaction phenomena, and serve as prototype system for examining theoretical models.

Die Rotatorenmanschettenruptur und die Schulterinstabilitat lassen sich durch eine strukturierte Anamnese und eine korperliche Untersuchung gut voneinander abgrenzen. Das ist wegen der unterschiedlichen Therapieansatze von hoher Bedeutung.

Unter dem Begriff „Schultersteife“ werden Erkrankungen subsummiert, deren Leitsymptom die eingeschrankte aktive und passive Beweglichkeit der Schulter ist. Im Allgemeinen versteht man darunter die sogenannte Frozen Shoulder mit ihrem typischen zyklischen Krankheitsverlauf. Von dieser primaren Schultersteife sind die sekundare Formen abzugrenzen, bei denen andere Ursachen die Bewegunglichkeit des Schultergelenks einschranken.

In this paper, we present two algorithms based on the Froidure-Pin Algorithm for computing the structure of a finite semigroup from a generating set. As was the case with the original algorithm of Froidure and Pin, the algorithms presented here produce the left and right Cayley graphs, a confluent terminating rewriting system, and a reduced word of the rewriting system for every element of the semigroup. If U is any semigroup, and A is a subset of U, then we denote by the least subsemigroup of U containing A. If B is any other subset of U, then, roughly speaking, the first algorithm we present describes how to use any information about , that has been found using the Froidure-Pin Algorithm, to compute the semigroup . More precisely, we describe the data structure for a finite semigroup S given by Froidure and Pin, and how to obtain such a data structure for from that for . The second algorithm is a lock-free concurrent version of the Froidure-Pin Algorithm. Postprint

Two finitely generated monoids are constructed, one finitely presented, the other not, whose (directed, unlabelled) Cayley graphs are isomorphic. Postprint

Bei Schmerzen, Kraftminderung, Bewegungseinschrankungen und Instabilitat im Schulterbereich sind eine systematische Anamnese und klinische Untersuchung des Schultergelenks unabdingbar. In vielen Fallen lasst sich dadurch bereits eine Diagnose stellen, die durch den gezielten Einsatz bildgebender Verfahren bestatigt werden kann.

The photoluminescence from aligned 7-atom wide armchair-edge graphene nanoribbons coupled to plasmonic nanoantennas was recently observed to display blinking. Photoluminescence blinking is a hallmark of emission from single quantum emitters. Here we explore the origin of the blinking. We study the influence of the local field enhancement in the vicinity of nanoantennas on the photoluminescence blinking. We observe a clear correlation between the blinking amplitudes and the plasmonic enhancement. For non-resonant metal nanostructures the blinking vanishes almost completely. Our results allow us to conclude that the blinking is an intrinsic feature of the emission from the graphene nanoribbons. This is in contrast to the case of single-molecule surface-enhanced Raman scattering, where it is known that ballistic charge transfer between plasmonic nanoparticles and the molecule under study critically contributes to the blinking.

On the one hand, process simulation has become an inherent part of design, engineering and operation of chemical production plants. On the other hand, process industry is moving to highly automated plants, with a distributed control system (DCS) at the core of these facilities. Considering both trends the integration of a process model into a DCS is the consecutive next step, which enables the online use of process models during plant operation. The details of technical integration as well as specific use cases such as soft-sensors and real-time optimization will be presented in this contribution. As introduction, a brief review of applications of simulation along the life-cycle of a process plant is given, leading to a vision for a digital twin concept.

Armchair graphene nanoribbons (AGNRs) with tunable band gap are a promising material for optoelectronic devices. We have earlier investigated the optical properties of seven atom wide AGNRs (7-AGNRs) and shown how photoluminescence emission at 1.8 eV is boosted via formation of defects in the atomic lattice of the ribbons by hydrogenation or by a photochemical process [1]. Here we probe the origin of this modification by measuring the extinction spectrum of a layer of AGNRs and demonstrate photodetection using AGNRs.

All authors thank the DFG (Wa 3089/6-1) and the EPSRC CCP CoDiMa (EP/M022641/1) for supporting this work. The first author would like to thank the Royal Society, and the EPSRC (EP/M003728/1). The third author would like to acknowledge support from the OpenDreamKit Horizon 2020 European Research Infrastructures Project (#676541). The first and third author thank the Algebra group at the Martin-Luther Universität Halle-Wittenberg for the hospitality and the inspiring environment. The fourth author wishes to thank the Computer Science Department of the University of St Andrews for its hospitality during numerous visits. We describe a family of new algorithms for finding the canonical image of a set of points under the action of a permutation group. This family of algorithms makes use of the orbit structure of the group, and a chain of subgroups of the group, to efficiently reduce the amount of search that must be performed to find a canonical image. We present a formal proof of correctness of our algorithms and describe experiments on different permutation groups that compare our algorithms with the previous state of the art. Publisher PDF

This paper studies the classes of semigoups and monoids with context-free and deterministic context-free word problem. First, some examples are exhibited to clarify the relationship between these classes and their connection with the notions of word-hyperbolicity and automaticity. Second, a study is made of whether these classes are closed under applying certain semigroup constructions, including direct products and free products, or under regressing from the results of such constructions to the original semigroup(s) or monoid(s)., 19 pages

We measure the absolute absorbance of a single layer of seven atom wide armchair graphene nanoribbons and study the influence of laser-induced defects on the absorption spectrum of the ribbons. We find that the absorption spectrum shows a broad peak at approximately 2.4 eV that is attributed to excitonic transitions and a smaller peak at 1.77 eV. The low-energy peak is diminished when we induce defects in the material. Simultaneously the photoluminescence is significantly enhanced. We thus attribute the 1.77 eV spectral feature in the absorption spectrum to a quenching state, which energetically coincides with the emission. Our results clearly demonstrate the significance of this state in photoluminescence processes in the ribbons. We additionally measure the dependence of the generation of defects on the energy of the incident photons and the photoluminescence excitation spectrum. The photoluminescence excitation efficiency peaks at a higher photon energy than the maximum absorption, hinting at an efficient decay from higher energetic states to the emissive state.

BACKGROUND Patients with atrial fibrillation (AF) have an increased risk of cognitive decline, potentially resulting from clinically unrecognized vascular brain lesions. OBJECTIVES This study sought to assess the relationships between cognitive function and vascular brain lesions in patients with AF. METHODS Patients with known AF were enrolled in a multicenter study in Switzerland. Brain magnetic resonance imaging (MRI) and cognitive testing using the Montreal Cognitive Assessment (MoCA) were performed in all participants. Large noncortical or cortical infarcts (LNCCIs), small noncortical infarcts (SNCIs), microbleeds, and white matter lesions were quantified by a central core laboratory. Clinically silent infarcts were defined as infarcts on brain MRI in patients without a clinical history of stroke or transient ischemic attack. RESULTS The study included 1,737 patients with a mean age of 73 ± 8 years (28% women, 90% taking oral anticoagulant agents). On MRI, LNCCIs were found in 387 patients (22%), SNCIs in 368 (21%), microbleeds in 372 (22%), and white matter lesions in 1715 (99%). Clinically silent infarcts among the 1,390 patients without a history of stroke or transient ischemic attack were found in 201 patients with LNCCIs (15%) and 245 patients with SNCIs (18%). The MoCA score was 24.7 ± 3.3 in patients with and 25.8 ± 2.9 in those without LNCCIs on brain MRI (p < 0.001). The difference in MoCA score remained similar when only clinically silent LNCCIs were considered (24.9 ± 3.1 vs. 25.8 ± 2.9; p < 0.001). In a multivariable regression model including all vascular brain lesion parameters, LNCCI volume was the strongest predictor of a reduced MoCA (β = -0.26; 95% confidence interval: -0.40 to -0.13; p < 0.001). CONCLUSIONS Patients with AF have a high burden of LNCCIs and other brain lesions on systematic brain MRI screening, and most of these lesions are clinically silent. LNCCIs were associated with worse cognitive function, even among patients with clinically silent infarcts. Our findings raise the question of MRI screening in patients with AF.

We couple photoluminescent semiconducting 7-atom wide armchair edge graphene nanoribbons to plasmonic nanoantenna arrays and demonstrate an enhancement of the photoluminescence and Raman scattering intensity of the nanoribbons by more than an order of magnitude averaged over large areas, and by three orders of magnitude in the hot spots of plasmonic antennas. The increase in signal allows us to study Raman spectra with high signal-to-noise ratio. Using plasmonic enhancement we are able to detect the off-resonant Raman scattering from the modified radial breathing-like mode (RBLM) due to physisorbed molecules, the 3rd order RBLM, and C-H vibrations. We find excellent agreement between experimental data and simulations describing the spectral dependence of the enhancement and modifications of the polarization anisotropy. The strong field gradients in the optical near-field further allow us to probe the subwavelength coherence properties of the phonon modes in the nanoribbons. We theoretically model this considering a finite phonon correlation length along the GNR direction. Our results allow estimating the correlation length in graphene nanoribbons.

Plasmon resonant arrays or meta-surfaces shape both the incoming optical field and the local density of states for emission processes. They provide large regions of enhanced emission from emitters and greater design flexibility than single nanoantennas. This makes them of great interest for engineering optical absorption and emission. Here we study the coupling of a single quantum emitter, a self-assembled semiconductor quantum dot, to a plasmonic meta-surface. We investigate the influence of the spectral properties of the nanoantennas and the position of the emitter in the unit cell of the structure. We observe a resonant enhancement due to emitter-array coupling in the far-field regime and find a clear difference from the interaction of an emitter with a single antenna.

One-dimensional (1D) graphene nanoribbons (GNRs) are promising materials for future electronics and optoelectronics. Their versatility in electronic properties makes it possible to use them as an active element in devices with a tunable band gap. Different from graphene, armchair-edge GNRs (AGNRs) are semiconducting with a direct bandgap [1-3]. However, until now their photophysical characterization has not been addressed properly due to the metal substrate on which they are grown. The substrate hinders measurements such as transmission and photoluminescence (PL). Here we transfer AGNRs with a width of N = 7 atoms from Au(788) to insulating substrates using an alignment-preserving method and investigate their photoluminescence properties.

© 2017 American Chemical Society. We demonstrate the alignment-preserving transfer of parallel graphene nanoribbons (GNRs) onto insulating substrates. The photophysics of such samples is characterized by polarized Raman and photoluminescence (PL) spectroscopies. The Raman scattered light and the PL are polarized along the GNR axis. The Raman cross section as a function of excitation energy has distinct excitonic peaks associated with transitions between the one-dimensional parabolic subbands. We find that the PL of GNRs is intrinsically low but can be strongly enhanced by blue laser irradiation in ambient conditions or hydrogenation in ultrahigh vacuum. These functionalization routes cause the formation of sp3 defects in GNRs. We demonstrate the laser writing of luminescent patterns in GNR films for maskless lithography by the controlled generation of defects. Our findings set the stage for further exploration of the optical properties of GNRs on insulating substrates and in device geometries.