Technische Universität Dresden: Qucosa
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ViewR: architectural-Scale Multi-User Mixed Reality With Mobile Head-Mounted Displays
No full textThe emergence of mobile head-mounted displays with robust “inside-out” markerless tracking and video-passthrough permits the creation of novel mixed reality (MR) experiences in which architectural spaces of arbitrary size can be transformed into immersive multi-user visualisation arenas. Here we outline ViewR, an open-source framework for rapidly constructing and deploying architectural-scale multi-user MR experiences. ViewR includes tools for rapid alignment of real and virtual worlds, tracking loss detection and recovery, user trajectory visualisation and world state synchronisation between users with persistence across sessions. ViewR also provides control over the blending of the real and the virtual, specification of site-specific blending zones, and video-passthrough avatars, allowing users to see and interact with one another directly. Using ViewR, we explore the transformation of large architectural structures into immersive arenas by creating a range of experiences in various locations, with a particular focus on architectural affordances such as mezzanines, stairs, gangways and elevators. Our tests reveal that ViewR allows for experiences that would not be possible with pure virtual reality, and indicate that, with certain strategies for recovering from tracking errors, it is possible to construct large scale multi-user MR experiences using contemporary consumer virtual reality head-mounted displays
A social-oriented approach for Master Production Scheduling
No full textNumerous researchers have studied social aspects of hierarchical production planning. This work responds to research gaps identified in previous literature reviews. According to this, there is a need to consider social aspects and the economic impact of social improvements in a longer-term planning approach. To this end, work intensity as employee utilization is integrated into a general mixed-integer programming model for master production scheduling. Following existing fatigue functions, the relationship between work intensity and exhaustion is represented by an exhaustion function that depends on employee utilization. The economic implications are taken into account by exhaustion-dependent capacity load factors. It is demonstrated that the consideration of economic implications is necessary to evaluate social improvements. Otherwise, the monetary disadvantages are overestimated and the social improvements are negatively influenced. In addition, from a certain degree of work intensity reduction, demand peaks are smoothed out more strongly by pre-production, which requires more core employees, while the use of temporary employment is reduced.Zahlreiche Forscher haben sich mit sozialen Aspekten der hierarchischen Produktionsplanung befasst. Mit dieser Arbeit wird auf Forschungslücken reagiert, die in früheren Literaturübersichten festgestellt wurden. Demnach ist die Berücksichtigung sozialer Aspekte und der wirtschaftlichen Auswirkungen sozialer Verbesserungen in einem längerfristigen Planungsansatz erforderlich. Zu diesem Zweck wird die Arbeitsintensität als Mitarbeiterauslastung in ein allgemeines gemischt-ganzzahliges Programmierungsmodell für die Hauptproduktionsprogrammplanung integriert. In Anlehnung an bestehende Ermüdungsfunktionen wird die Beziehung zwischen Arbeitsintensität und Erschöpfung durch eine von der Mitarbeiterauslastung abhängige Erschöpfungsfunktion dargestellt. Die ökonomischen Implikationen werden durch erschöpfungsabhängige Kapazitätsbelastungsfaktoren berücksichtigt. Es wird gezeigt, dass die Berücksichtigung ökonomischer Implikationen notwendig ist, um soziale Verbesserungen zu bewerten. Andernfalls werden die monetären Nachteile überschätzt und die sozialen Verbesserungen werden dadurch negativ beeinflusst. Darüber hinaus werden ab einem bestimmten Grad der Arbeitsintensitätsreduzierung Nachfragespitzen stärker durch Vorproduktion geglättet, was eine höhere Stammbelegschaft erfordert, während der Einsatz von Leiharbeit reduziert wird
Dairy milk fouling detection using electrical resistance tomography.
No full textFouling during dairy milk processing presents a significant challenge, leading to energy inefficiency and product contamination. This study investigated the potential of Electrical Resistance Tomography (ERT) to detect fouling in dairy milk processing systems in a laboratory study. The laboratory setup consisted of a tank with 16 sensors and saline water with a conductivity of 5.23 mS/cm as the working fluid. Stainless steel cups were CNC-cut and loaded with foulants to match the varying fouling layer thicknesses, and were positioned in the tank to simulate fouling. Three distinct fouling thicknesses were generated by heating skim milk and whey protein at 80°C for various time periods. A reference measurement was obtained using a clean stainless-steel cup, and subsequent measurements with fouled cups were compared to generate conductivity maps. These tomographic images were statistically analysed and demonstrated a significant difference between the reference and fouled states. This study elucidates the potential of ERT for identifying fouling through changes in conductivity, and the tomograms clearly differentiate between the three fouling levels. Future research will focus on determining the minimum detectable fouling thickness and establishing a more precise correlation between the fouling layer thickness and conductivity changes and techniques such as Convolutional Neural networks. This approach offers a promising, non-invasive method for monitoring fouling in real time, potentially providing significant benefits to the dairy industry
Predictive fouling detection in dairy industry heat exchangers using sequence-to-sequence deep learning models
No full textFouling in heat exchangers challenges heat transfer efficiency, making its predictive detection crucial for the dairy industry. Despite numerous sensors integrated into production facilities, valuable data relevant to fouling prediction often remains underutilized. This study evaluates three Sequence-to-Sequence deep learning models—Long Short-Term Memory (LSTM), Encoder-Decoder LSTM, and Convolutional Neural Network LSTM (CNN-LSTM) to predict sensor profiles several minutes into the future and to estimate fouling based on a dataset from a full-scale dairy heat exchanger. Sensor data such as inlet hot water temperature, outlet product pressure, and pump power were treated as indicator for fouling and analyzed to estimate it. Evaluation metrics include mean squared error and mean absolute scaled error. Of the models tested, CNN-LSTM showed the lowest prediction error 12.3 for estimating the outlet product pressure, offering potential for early fouling detection in industrial applications. These findings demonstrate the feasibility of deep learning for improving heat exchanger maintenance strategies
Session 6 - Strategies and best practices in cleaning and disinfection; Chairwoman: Kathryn Whitehead
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The emergence of time with interactions in quantum and classical mechanics
No full textPhysicists are nowadays able to produce and measure light pulses with durations on the inconceivably small scale of attoseconds. While this allows them to probe and explore the dynamics of the most fundamental processes of the physical world on ever shorter time scales, the explicit nature of time itself still remains a mystery even today. This unresolved issue divides the scientific community into two distinct camps. Those in the first camp view time as a fundamental entity of nature, while those in the second camp view it as an effective or emergent quantity derived from more elementary principles. Proponents of the latter view advocate for a static global state as the fundamental entity, in which the whole encompasses a principal “system” and a “clock” as separate subsystems. In this context, the central notion is that of a state of the principal system being conditioned on the physical state of the clock. As a result, time or, more concretely, dynamics emerges from the inherent correlations between both subsystems contained in the global state. Two prominent quantum mechanical approaches for this “timeless” theory have been developed during the last decades. The first relies on a semiclassical treatment in the form of Born-Oppenheimer and Wentzel-Kramers-Brillouin approximations, but allows one to include interactions between system and clock. A second treatment, devised by Page and Wootters, works in abstract Hilbert space instead. Unfortunately, it is as of yet unable to generally deal with interactions and often relies on Hamiltonians of a special form.
The main objective of this thesis is to close the gap between both approaches through construction of an overarching framework in full generality, without relying on specific choices for the underlying subsystems or the Hamiltonians involved. To this end, we single out three central principles on which the previous approaches build, namely a global energy constraint, the existence of subsystems and a definition of the conditional state of the principal system. Based on them, we derive unitary system dynamics and the time-dependent Schrödinger equation with an exact memoryless effective potential from a timeless quantum mechanical formulation, namely the time-independent Schrödinger equation. We find that the traditionally presupposed time is replaced by a scalar path variable parametrizing a global state invariance generated by the energy constraint. Yet, this derivation deals exclusively with pure states and, to widen its scope, we extend the timeless approach to quantum mechanical mixed states and classical probability densities as well. A key concept is the minimization of a unitarity-violating term in the evolution equations, appearing in the presence of an interaction term between system and clock. Useful approximations and analytical and numerical examples complement our results and corroborate our derivations. As a further demonstration of the versatility of our approach, we explain how a long-suspected connection between imaginary-time formulations and inverse temperature in canonical ensembles could be traced to a common physical origin. Finally, we discuss the consequences of our newly developed framework, especially similarities to conventional open systems theory, and conclude with an outlook for future investigations
Collective dynamics of networked, nonlinear, and oscillatory systems
No full textHumanity today heavily relies on a multitude of nonlinear networked infrastructure systems that enable our communication and mobility as well, as the supply of water, gas, or electricity. Driving a network from the outside, increasing its connectivity or upgrading it, i.e., changing system parameters, may qualitatively change their collective dynamics. In particular, such changes may make systems more vulnerable to failure or dysfunction at all scales, also because experts on microscopic details in a given specific field of application may overlook implications on macroscopic and generic system dynamics.
In this work, we identify nonlinear phenomena and propose and work out mathematical analysis and approximation tools that help understand the dynamics of nonlinear and networked systems, supplementing the existing toolbox on complex systems in two directions.
First, we present a framework for analyzing the collective dynamics of generic nonlinear non-autonomous systems that are externally driven by fluctuations. We reveal a nonlinear average response to fluctuations and demonstrate that it is – despite largely absent in standard literature – present in almost all systems. Nonlinear systems thus generically exhibit average response dynamics that are shifted away from their original operating point despite being driven by zero-mean fluctuations. To predict these shifts, we work out a second-order response theory for general network dynamical systems. Furthermore, we introduce an analytical no-tipping condition, a self-consistency scheme that informs us about the driving amplitude up to which a nonlinear system is safely operable, i.e., exhibits responses local to its original operating point. Beyond that amplitude, systems tip and exhibit qualitatively different response dynamics. We illustrate the network response framework by examples of two classes of power grids models, with and without active voltage dynamics, demonstrating their applicability.
Second, we propose to analytically continue real-variable model systems to feature complex variables (and parameters) to help to understand their autonomous collective dynamics, in particular the transition to synchrony. We apply such a complexification to the paradigmatic Kuramoto model to gather insights into the transition to synchrony in finite-size populations. Analytical insights have been mostly limited to continuum dynamics to date, where derivations were based on the existence of stationary densities, while such invariants are missing in the relevant parameter regime for finite-size populations.
In the complexified systems, we demonstrate the existence of invariant states, complex locked states, for all allowed parameters. They help us to quantify the transition to synchrony in the finite-size real-variable systems. We furthermore generalize the mean-field approach and effective decoupling of variables to the analytically continued model by defining a quaternion order parameter. Such analytic model continuation and generalized order parameters may in the future help to understand collective dynamics, also beyond synchronization, of a range of networked systems.:Contents
Abstract 2
Zusammenfassung 3
1 Introduction 12
1.1 Driven nonlinear and networked systems . . . . . . . . . . . . . . . . . . . 12
1.2 Complexification as a tool to understand synchronization system dynamics 15
1.3 Synopsis of the thesis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
2 Fundamentals 17
2.1 Networks and basic concepts from graph theory . . . . . . . . . . . . . . . 17
2.2 Dynamical systems on networks . . . . . . . . . . . . . . . . . . . . . . . . 20
2.3 Mathematical methods for approximating dynamics and functions . . . . . 24
2.4 Power grid models . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
3 Fluctuation-driven, nonlinear and networked systems 31
3.1 Perturbation series for generic systems subject to external driving . . . . . 31
3.2 Power grid models in the framework of the general system settings . . . . . 33
3.3 Network of interacting variables . . . . . . . . . . . . . . . . . . . . . . . . 34
4 Linear response dynamics of driven systems 37
4.1 Derivation of the full linear response dynamics . . . . . . . . . . . . . . . . 37
4.2 Response regimes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
4.3 Response regimes extended to active voltage dynamics . . . . . . . . . . . 41
4.4 Localized response regime . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
4.5 Boosted fluctuation responses in power grids
with active voltage dynamics . . . . . . . . . . . . . . . . . . . . . . . . . . 46
4.6 Transient response arrival times . . . . . . . . . . . . . . . . . . . . . . . . 48
4.7 Responses arrive faster in power grids
with active voltage dynamics . . . . . . . . . . . . . . . . . . . . . . . . . . 50
4.8 Conclusion and outlook . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52
5 Nonlinear response dynamics of driven systems 56
5.1 Estimation of operating offset with second-order response theory . . . . . . 58
5.2 Operating offset theory for one-dimensional systems . . . . . . . . . . . . . 59
5.3 Operating offset theory for N-dimensional systems . . . . . . . . . . . . . . 61
5.4 Summary and outlook . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62
6 Analytical no-tipping condition for driven nonlinear systems 64
6.1 No-tipping condition for one-dimensional systems . . . . . . . . . . . . . . 64
6.2 No-tipping condition for asymmetrical systems . . . . . . . . . . . . . . . . 66
6.3 No-tipping condition for symmetrical systems . . . . . . . . . . . . . . . . 68
6.4 Approximations of the no-tipping condition . . . . . . . . . . . . . . . . . . 71
6.5 Naive approaches determining tipping points . . . . . . . . . . . . . . . . . 74
6.6 No-tipping condition for N-dimensional systems . . . . . . . . . . . . . . . 76
6.7 Critical perturbation strength for a synchronous generator . . . . . . . . . 77
6.8 Discussion and Outlook . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80
7 Synchronization in finite-size populations 82
7.1 Background and state of the art . . . . . . . . . . . . . . . . . . . . . . . . 84
7.1.1 The Adler equation . . . . . . . . . . . . . . . . . . . . . . . . . . . 84
7.1.2 The Winfree model . . . . . . . . . . . . . . . . . . . . . . . . . . . 85
7.1.3 The Kuramoto model . . . . . . . . . . . . . . . . . . . . . . . . . . 86
7.2 Analytic continuation to the complex plane . . . . . . . . . . . . . . . . . . 93
7.3 Analytic continuation of Kuramoto dynamics to the complex plane . . . . 95
7.3.1 Two-dimensional case . . . . . . . . . . . . . . . . . . . . . . . . . . 96
7.3.2 Complex locked states persist for all positive coupling strengths and
system sizes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102
7.3.3 Complex locked states help to determine finite order transition . . . 108
7.4 Mean field approach of the complexified Kuramoto model . . . . . . . . . . 113
7.4.1 The original order parameter is invalid on the complex plane . . . . 113
7.4.2 Quaternion order parameter redefines the original Kuramoto order
parameter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 114
7.4.3 Self-consistent approach to access complex locked states . . . . . . . 118
7.4.4 Continuum dynamics . . . . . . . . . . . . . . . . . . . . . . . . . . 119
7.5 Discussion and Outlook . . . . . . . . . . . . . . . . . . . . . . . . . . . . 120
8 Conclusion 123
8.1 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 123
8.2 Discussion and outlook . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 125
Bibliography 12
Two examples concerning existential undecidability in fields
No full textWe construct an existentially undecidable complete discretely valued field of mixed characteristic with existentially decidable residue field and decidable algebraic part, answering a question by Anscombe–Fehm in a strong way. Along the way, we construct an existentially decidable field of positive characteristic with an existentially undecidable finite extension, modifying a construction due to Kesavan Thanagopal
Summary
No full textCrises are part of life on earth and varying in scale (local, regional, global) and time (from short term to long term). Many of them are relevant for forestry and forestry education. Specially, the Covid-191 pandemic is a drastic example, which has had negative impacts on teaching and learning. In his introduction NORBERT WEBER (president of the SILVA Network) stated that this crisis perhaps could have a positive side-effect in a growing competence in digital teaching and learning in higher forestry education. Some examples are discussed below, expanded, as is the tradition in the SILVA Network, with contributions concerning higher forestry education