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Im Rahmen von Industrie 4.0 gilt das Konzept der Verwaltungsschale als eines der zentralen Ergebnisse. In diesem Beitrag wird das vom Lehrstuhl für Informations- und Automatisierungssysteme für die Prozess- und Werkstofftechnik der RWTH Aachen University entwickelte Python-SDK PyI40AAS zwei Jahre nach Beginn der Arbeiten vorgestellt. Es ist eine Realisierung des von der Plattform Industrie 4.0 veröffentlichten technologieneutralen UML-Modells für die Repräsentation von Informationen in der Verwaltungsschale. Zudem werden einige Design-Entscheidungen bei der Implementierung beleuchtet unddaraus Empfehlungen zur Weiterentwicklung des Metamodells abgeleitet.

Steffen Ganghof’s Beyond Presidentialism and Parliamentarism: Democratic Design and the Separation of Powers (Oxford University Press, 2021) posits that “in a democracy, a constitutional separation of powers between the executive and the assembly may be desirable, but the constitutional concentration of executive power in a single human being is not” (Ganghof, 2021). To consider, examine and theorise about this, Ganghof urges engagement with semi-parliamentarism. As explained by Ganghof, legislative power is shared between two democratically legitimate sections of parliament in a semi-parliamentary system, but only one of those sections selects the government and can remove it in a no-confidence vote. Consequently, power is dispersed and not concentrated in the hands of any one person, which, Ganghof argues, can lead to an enhanced form of parliamentary democracy. In this book review symposium, George Tsebelis, Michael Thies, José Antonio Cheibub, Rosalind Dixon and Daniel Bogéa review Steffen Ganghof’s book and engage with the author about aspects of research design, case selection and theoretical argument. This symposium arose from an engaging and constructive discussion of the book at a seminar hosted by Texas A&M University in 2022. We thank Prof José Cheibub (Texas A&M) for organising that seminar and Dr Anna Fruhstorfer (University of Potsdam) for initiating this book review symposium.

We reconsider the two-flavor version of the massive, chiral Gross-Neveu model in 1+1 dimensions. Its phase diagram as a function of baryon chemical potential, isospin chemical potential and temperature has previously been explored. We recapitulate the results, adding the missing tricritical curves. They can be determined exactly by extending the standard stability analysis, using fourth order almost degenerate perturbation theory. Results for three different bare masses are presented and discussed., Comment: 9 pages, 16 figures

In the massive chiral Gross-Neveu model, a phase boundary separates a homogeneous from an inhomogeneous phase. It consists of two parts, a second order line and a first order line, joined at a tricritical point. Whereas the first order phase boundary requires a full, numerical Hartree-Fock calculation, the second order phase boundary can be determined exactly and with less effort by a perturbative stability analysis. We extend this stability analysis to higher order perturbation theory. This enables us to locate the tricritical point exactly, without need to perform a Hartree-Fock calculation. Divergencies due to the emergence of spectral gaps in a spatially periodic perturbation are handled using well established tools from many body theory., Comment: 16 pages, 11 figures; v2: typo's corrected; v3: minor improvements

The Gross-Neveu model with ${\rm U}_L(N_f)\times{\rm U}_R(N_f)$ chiral symmetry is reconsidered in the large $N_c$ limit. The known analytical solution for the time dependent interaction of any number of twisted kinks and breathers is cast into a more revealing form. The ($x,t$)-dependent factors are isolated from constant coefficients and twist matrices. These latter generalize the twist phases of the single flavor model. The crucial tool is an identity for the inverse of a sum of two square matrices, derived from the known formula for the determinant of such a sum., 20 pages, no figure; v2: A remark and a reference added

We consider a version of the Gross-Neveu model in 1+1 dimensions with discrete chiral and continuous flavor symmetry (isospin). In 2+1 dimensions, this model is known as chiral Heisenberg Gross-Neveu model. Spontaneous symmetry breaking and the emergence of two massless and one massive scalar bosons are shown. A duality to the Nambu--Jona-Lasinio model with isospin is exhibited, provided that the isovector pseudoscalar mean field is constrained to a plane in isospin space. This enables us to find the phase diagram as a function of temperature, chemical potential and isospin chemical potential as well as twisted kinks. A bare mass term acts quite differently when added to this model as compared to other chiral variants of the Gross-Neveu model., 11 pages, 2 figures

The massive two-dimensional Nambu--Jona-Lasinio model with isospin (isoNJL) is reconsidered in the large $N_c$ limit. We continue the exploration of its phase diagram by constructing missing first-order phase boundaries. At zero temperature, a phase boundary in the plane of baryon and isospin chemical potentials separates the vacuum from a crystal phase. We derive it from the baryon spectrum of the isoNJL model which, in turn, is obtained via a numerical Hartree-Fock (HF) calculation. At finite temperature, a first-order phase boundary sheet is found using a thermal HF calculation. It interpolates smoothly between the zero temperature phase boundary and the perturbative sheet. The calculations remain tractable owing to the assumption that the charged pion condensate vanishes. In that case, most of the calculations can be done with methods developed in the past for solving the massive one-flavor NJL model., 13 pages, 2 tables, 6 figures; v2: typos corrected

The phase diagram of the two-dimensional Nambu--Jona-Lasinio model with isospin is explored in the large Nc limit with semiclassical methods. We consider finite temperature and include chemical potentials for all conserved charges. In the chiral limit, a full analytical solution is presented, expressed in terms of known results for the single-flavor Gross-Neveu and Nambu--Jona-Lasinio models. A novel crystalline structure appears and is shown explicitly to be thermodynamically more stable than the homogeneous phase at zero temperature. If we include a bare fermion mass, the problem reduces again to solved problems in one-flavor models provided that either the fermionic or the isospin chemical potentials vanish. In the general case, a stability analysis is used to construct the perturbative phase boundary between homogeneous and inhomogeneous phases. This is sufficient to get a good overview of the complete phase diagram. Missing non-perturbative phase boundaries requiring a full numerical Hartree-Fock calculation will be presented in future work., Comment: 14 pages, 8 figures; v2: references added, typos corrected

With more and more event-based neuromorphic hardware systems being developed at universities and in industry, there is a growing need for assessing their performance with domain specific measures. In this work, we use the methodology of converting pre-trained non-spiking to spiking neural networks to evaluate the performance loss and measure the energy-per-inference for three neuromorphic hardware systems (BrainScaleS, Spikey, SpiNNaker) and common simulation frameworks for CPU (NEST) and CPU/GPU (GeNN). For analog hardware we further apply a re-training technique known as hardware-in-the-loop training to cope with device mismatch. This analysis is performed for five different networks, including three networks that have been found by an automated optimization with a neural architecture search framework. We demonstrate that the conversion loss is usually below one percent for digital implementations, and moderately higher for analog systems with the benefit of much lower energy-per-inference costs., The final authenticated publication is available at Springer via https://doi.org/10.1007/978-3-030-61616-8_49

In the field of neuromorphic computing several hardware accelerators for spiking neural networks have been introduced, but few studies actually compare different systems. These comparative studies reveal difficulties in porting an existing network to a specific system and in predicting its performance indicators. Finding a common network architecture that is suited for all target platforms and at the same time yields decent results is a major challenge. In this contribution, we show that a winner-takes-all inspired network structure can be employed to solve Sudoku puzzles on three diverse hardware accelerators. By exploring several network implementations, we measured the number of solved puzzles in a set of 100 assorted Sudokus, as well as time and energy to solution. Concerning the last two indicators, our measurements indicate that it can be beneficial to port a network to an analogue hardware system.

The phase diagram of the two-dimensional Nambu-Jona-Lasinio (or chiral Gross-Neveu) model is characterized by an order parameter in the form of a chiral spiral. Its radius vanishes at a critical temperature, its period depends only on the chemical potential. We generalize these findings to chirally imbalanced systems by including a chiral chemical potential $\mu_5$. The relationship between the present, static approach and a previous, time dependent one is traced back to a half-local symmetry which the NJL$_2$ model shares with massless Dirac fermions, but which has been neglected so far. The structure of chiral spiral matter is further elucidated by computing fermion and antifermion momentum distribution functions, using a Bogoliubov transformation., Comment: 11 pages, 13 figures, v2: Extended comparison with previous works, 2 references added, typos corrected

As a consequence of axial current conservation, fermions cannot be localized in the massless NJL$_2$ model. In the case of twisted kinks, this manifests itself in a cancellation between valence fermion density and fermion density induced in the Dirac sea. To attribute the correct fermion number to these bound states requires an infrared regularization. Recently, this has been achieved by introducing a bare fermion mass, at least in the non-relativistic regime of small twist angles and fermion numbers. Here, we propose a simpler regularization by a finite box which preserves integrability and can be applied at any twist angle. A consistent and physically plausible assignment of fermion number to all twisted kinks emerges.

Twisted kinks in the massless NJL$_2$ model interpolate between two distinct vacua on the chiral circle. If one approaches the chiral limit from finite bare fermion masses $m_0$, the vacuum is unique and twist cannot exist. This issue is studied analytically in the non-relativistic limit, using a no-sea effective theory. We conclude that even in the massless limit, the interpretation of the twisted kink has to be revised. One has to attribute the fermion number of the valence state to the twisted kink. Fermion density is spread out over the whole space due to the massless pion field. The result can be pictured as a composite of a twisted kink (carrying energy, but no fermion number) and a partial winding of the chiral spiral (carrying fermion number, but no energy). This solves at the same time the puzzle of missing baryons with fermion number $N_f

Due to integrability, baryon-baryon scattering in the massless Gross-Neveu model at large N features only forward elastic scattering. A bare mass term breaks integrability and is therefore expected to induce backward elastic scattering as well as inelastic reactions. We confirm these expectations by a study of baryon-baryon scattering in the massive Gross-Neveu model near the non-relativistic limit. This restriction enables us to solve the time-dependent Hartree-Fock equations with controlled approximations, using a combination of analytical methods from an effective field theory and the numerical solution of partial differential equations., Comment: 14 pages, 18 figures

The two-dimensional, massless Gross-Neveu model with Nc colors and SU(2) isospin is studied analytically in the large Nc limit. The chiral SU(2)L X SU(2)R symmetry is broken spontaneously in the vacuum. Twisted kinks connecting two arbitrary points on the vacuum manifold S3 are constructed, and their properties are explored. The phase diagram as a function of temperature, baryon- and isospin chemical potential is discussed, with special emphasis on inhomogeneous phases. The preferred form of the condensate is a product of the real kink crystal and the chiral spiral. Kink-kink scattering is solved, using the general solution of the multicomponent Bogoliubov-de Gennes equation recently presented by Takahashi., Comment: 16 pages, no figure; v2: 2 figures, 2 references and short discussion added in sect. V, typos corrected, 17 pages

Parallel programming and effective partitioning of applications for embedded many-core architectures requires optimization algorithms. However, these algorithms have to quickly evaluate thousands of different partitions. We present a fast performance estimator embedded in a parallelizing compiler for streaming applications. The estimator combines a single execution-based simulation and an analytic approach. Experimental results demonstrate that the estimator has a mean error of 2.6% and computes its estimation 2848 times faster compared to a cycle accurate simulator.

Margin-closed itemsets have previously been proposed as a subset of the closed itemsets with a minimum margin constraint on the difference in support to supersets. The constraint reduces redundancy in the set of reported patterns favoring longer, more specific patterns. A variety of patterns ranging from rare specific itemsets to frequent general itemsets is reported to support exploratory data analysis and understandable classification models. We present DCI_Margin, a new efficient algorithm that mines the complete set of margin-closed itemsets. We modified the DCI_Closed algorithm that has low memory requirements and can be parallelized. The margin constraint is checked on-the-fly reusing information already computed by DCI_Closed. We thoroughly analyzed the behavior on many datasets and show how other data mining algorithms can benefit from the redundancy reduction.

We present a 2D- and 3D-lattice Boltzmann model for the treatment of free surface flows including gas diffusion. Interface advection and related boundary conditions are based on the idea of the lattice Boltzmann equation. The fluid dynamic boundary conditions are approximated by using the mass and momentum fluxes across the interface, which do not require explicit calculation of gradients. A similar procedure is applied to fulfill the diffusion boundary condition. Simple verification tests demonstrate the correctness of the algorithms. 2D- and 3D-foam evolution examples demonstrate the potential of the method.

A method and algorithm for reconstructing the three-dimensional (3D) surface of stems based on terrestrial laser scanner data from standing trees is presented. Laser scanning delivers a dense cloud of points, and this raw point data are filtered for deriving a digital terrain model and subsequent fitting of a parametric stem model. The stem model is made up of a sequence of successive cylinders that overlap in space; each cylinder is parameterized by its orientation and radius. The model is estimated iteratively from a given starting point and by adding cylinder segments. Successive segments are added whenever criteria on deviation in orientation and radius relative to the previous cylinder and a fit statistic to the point data are met. The method has proven applicable when applied to a European beech tree and a wild cherry tree from dense forest stands. The use of the resulting 3D reconstruction of tree stems in respect to diameter in breast height and height of crown base calculation, as well as taper, ...

With the term Architecture/Compiler Co-exploration, we denote the problem of simultaneously optimizing an application-specific instruction set processor (ASIP) architecture as well as its generated compiler. In this paper, we characterize the design space of both compiler frontend (intermediate code optimization) and backend (changes of the machine model) and present the workflow of our framework BUILDABONG. The project consists of four phases: (a) architecture entry and composition, (b) automatic simulator generation, (c) compiler generation (in particular, retargeting), and (d) automatic architecture/compiler design space exploration. We demonstrate the feasibility of our approach by a detailed case study.