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The Connection Between Resistance Training, Climbing Performance, and Injury Prevention
Get PDFBackground: Climbing is an intricate sport composed of various disciplines, holds, styles, distances between holds, and levels of difficulty. In highly skilled climbers the potential for further strength-specific adaptations to increase performance may be marginal in elite climbers. With an eye on the upcoming 2024 Paris Olympics, more climbers are trying to maximize performance and improve training strategies. The relationships between muscular strength and climbing performance, as well as the role of strength in injury prevention, remain to be fully elucidated. This narrative review seeks to discuss the current literature regarding the effect of resistance training in improving maximal strength, muscle hypertrophy, muscular power, and local muscular endurance on climbing performance, and as a strategy to prevent injuries.
Main Body: Since sport climbing requires exerting forces against gravity to maintain grip and move the body along the route, it is generally accepted that a climber`s absolute and relative muscular strength are important for climbing performance. Performance characteristics of forearm flexor muscles (hang-time on ledge, force output, rate of force development, and oxidative capacity) discriminate between climbing performance level, climbing styles, and between climbers and non-climbers. Strength of the hand and wrist flexors, shoulders and upper limbs has gained much attention in the scientific literature, and it has been suggested that both general and specific strength training should be part of a climber`s training program. Furthermore, the ability to generate sub-maximal force in different work-rest ratios has proved useful, in examining finger flexor endurance capacity while trying to mimic real-world climbing demands. Importantly, fingers and shoulders are the most frequent injury locations in climbing. Due to the high mechanical stress and load on the finger flexors, fingerboard and campus board training should be limited in lower-graded climbers. Coaches should address, acknowledge, and screen for amenorrhea and disordered eating in climbers.
Conclusion: Structured low-volume high-resistance training, twice per week hanging from small ledges or a fingerboard, is a feasible approach for climbers. The current injury prevention training aims to increase the level of performance through building tolerance to performance-relevant load exposure and promoting this approach in the climbing field
Döpking, Lars: Fiskalische Herrschaft. Steuern, Staat und Politik in Italien seit 1945, 512 S., Hamburger Edition, Hamburg 2023.
Get PDFDer deutsche Leser – und nicht nur er – assoziiert beim Thema ‚Steuer – Italien‘ wohl in erster Linie Bestechung, Steuerflucht und brutale Razzien der Guardia di Finanza in den Urlaubsorten der Reichen und Schönen. Vielleicht weiß er auch, dass in Italien bis in die 1980er Jahre direkte Steuern vielfach von Steuerpächtern eingezogen wurden, und noch Ältere erinnern sich womöglich, dass nur wenig früher an den Ortseingängen noch Zollstellen waren, die dort von LKWs städtische Zuschlagsteuern kassierten. Und möglicherweise wurde ihm in den 1990er Jahren ja auch in Neapel oder anderswo im Süden nach dem Besuch eines Ladens oder Restaurants von „accompagnatori fiscali“ angeboten, sie die nächsten 500 Meter zu begleiten, um nötigenfalls den kontrollierenden ‚Finanzern‘ einen Kassenbon vorweisen zu können. Von allen diesen Dingen ist in Lars Döpkings Buch auch die Rede, aber es liefert keine Chronique scandaleuse, sondern seriöse Forschung
SSMSPC: self-supervised multivariate statistical in-process control in discrete manufacturing processes
Get PDFSelf-supervised learning has demonstrated state-of-the-art performance on various anomaly detection tasks. Learning effective representations by solving a supervised pretext task with pseudo-labels generated from unlabeled data provides a promising concept for industrial downstream tasks such as process monitoring. In this paper, we present SSMSPC a novel approach for multivariate statistical in-process control (MSPC) based on self-supervised learning. Our motivation for SSMSPC is to leverage the potential of unsupervised representation learning by incorporating self-supervised learning into the general statistical process control (SPC) framework to develop a holistic approach for the detection and localization of anomalous process behavior in discrete manufacturing processes. We propose a pretext task called Location + Transformation prediction, where the objective is to classify both, the type and the location of a randomly applied augmentation on a given time series input. In the downstream task, we follow the one-class classification setting and apply the Hotelling’s T² statistic on the learned representations. We further propose an extension to the control chart view that combines metadata with the learned representations to visualize the anomalous time steps in the process data which supports a machine operator in the root cause analysis. We evaluate the effectiveness of SSMSPC with two real-world CNC-milling datasets and show that it outperforms state-of-the-art anomaly detection approaches, achieving 100% and 99.6% AUROC, respectively. Lastly, we deploy SSMSPC at a CNC-milling machine to demonstrate its practical applicability when used as a process monitoring tool in a running process
Finite-Element Simulation of Homogenized Field Models for Foil Windings
Get PDFIn electrical engineering, foil windings are used in various application areas, such as transformers or magnet systems.
A foil winding is a coil that is built from winding a conducting foil that is insulated at its surface.
There exists a standard model that allows to efficiently simulate foil windings in a low to medium frequency range.
It uses a homogenization technique that prevents the resolution of the typically very thin foil and rather models the foil winding as a whole.
Currently, the switching frequency in power electronics components is increasing as higher frequencies allow to build smaller devices with better performance.
At higher frequencies, capacitive effects become relevant for foil windings.
They can drastically change the behavior of foil windings because above a certain frequency, a foil winding behaves like a capacitor and no longer like a coil.
Until now, there did not exist a general homogenization model for the simulation of foil windings that includes capacitive effects.
The standard model only considers resistive and inductive effects but neglects capacitive effects.
At the same time, a brute force simulation with a full resolution of the details in the foil winding is infeasible due to very high computational costs.
This dissertation develops a finite element model for foil windings that includes capacitive effects at moderate computational costs.
The model consists of two parts.
First, it uses a homogenization of the materials in the foil winding domain that allows to reduce the spatial resolution of the mesh, thereby reducing the computational costs immensely.
Second, it defines conditions that ensure the correct current to flow through the foil winding.
These conditions enforce conductive currents to flow through the turns and displacement currents to flow across the insulation between the turns.
Both parts of the model are implemented into the finite element solver Pyrit in Python.
The homogenization is validated and verified with high-resolution reference simulations.
Simulation results with the entire model are compared to measurement results for two distinct foil windings, showing the capability of the developed model to predict the behavior of foil windings for a large frequency range.
The simulations confirm the transition from a resistive behavior at low frequencies via an inductive behavior at medium frequencies to a capacitive behavior at high frequencies
Crystal structure of pentamethylpyrylium triiodide, [(CH₃)₅C₅O][I₃]
Get PDFC₁0H₁₅I₃O, orthorhombic, Pnma (no. 62), a = 13.750(3) Å, b = 7.288(2) Å, c = 15.140(3) Å, V = 1517.2 ų, Z = 4, Rgt(F) = 0.031, wRref(F²) = 0.071, T = 150 K
QUICK‐B‐WIM: Large scale application of a moving force identification method on a railway bridge
No full textGlobally, infrastructure faces the challenge of aging bridges and increasing traffic loads. Extended operational availability and safety of the bridge structures can be enabled by Structural Health Monitoring (SHM) methods. For this, knowledge of the actual vehicle loads is of crucial importance for evaluation of the remaining service life. Direct measurement of the moving loads, however, is either very cumbersome and requires considerable financial effort or in some cases even impossible. Bridge Weigh‐In‐Motion (B‐WIM) methods use the structural responses of bridge structures to determine the external vehicle loads. The present contribution deals with the testing of a novel moving force identification (MFI) method, denoted as Quick‐BWIM (QBWIM) under real operating conditions. In this study, 43 train crossings within 18 hours were investigated and compared with a nearby axle load measurement point. QBWIM achieves an average error of only 1.1% with a standard deviation of 7.5% for individual axles and an average error of 2.1% with a standard deviation of 1.5% for the identification of gross vehicle weights (GVW). This study shows that QBWIM can meet European and US guidelines even under poor conditions and is able to reliably determine axle loads in real time
Integrated-optics heralded controlled-NOT gate for polarization-encoded qubits
Get PDFRecent progress in integrated-optics technology has made photonics a promising platform for quantum networks and quantum computation protocols. Integrated optical circuits are characterized by small device footprints and unrivalled intrinsic interferometric stability. Here, we take advantage of femtosecond-laser-written waveguides’ ability to process polarization-encoded qubits and present an implementation of a heralded controlled-NOT gate on chip. We evaluate the gate performance in the computational basis and a superposition basis, showing that the gate can create polarization entanglement between two photons. Transmission through the integrated device is optimized using thermally expanded core fibers and adiabatically reduced mode-field diameters at the waveguide facets. This demonstration underlines the feasibility of integrated quantum gates for all-optical quantum networks and quantum repeaters
Biphoton generation in quadratic waveguide arrays: A classical optical simulation
Get PDFQuantum entanglement became essential in understanding the non-locality of quantum mechanics. In optics, this non-locality can be demonstrated on impressively large length scales, as photons travel with the speed of light and interact only weakly with their environment. Spontaneous parametric down-conversion (SPDC) in nonlinear crystals provides an efficient source for entangled photon pairs, so-called biphotons. However, SPDC can also be implemented in nonlinear arrays of evanescently coupled waveguides which allows the generation and the investigation of correlated quantum walks of such biphotons in an integrated device. Here, we analytically and experimentally demonstrate that the biphoton degrees of freedom are entailed in an additional dimension, therefore the SPDC and the subsequent quantum random walk in one-dimensional arrays can be simulated through classical optical beam propagation in a two-dimensional photonic lattice. Thereby, the output intensity images directly represent the biphoton correlations and exhibit a clear violation of a Bell-like inequality
Novel Insights into Enhanced Stability of Li‐Rich Layered and High‐Voltage Olivine Phosphate Cathodes for Advanced Batteries through Surface Modification and Electron Structure Design
Get PDFThe design of cathode/electrolyte interfaces in high‐energy density Li‐ion batteries is critical to protect the surface against undesirable oxygen release from the cathodes when batteries are charged to high voltage. However, the involvement of the engineered interface in the cationic and anionic redox reactions associated with (de‐)lithiation is often ignored, mostly due to the difficulty to separate these processes from chemical/catalytic reactions at the cathode/electrolyte interface. Here, a new electron energy band diagrams concept is developed that includes the examination of the electrochemical‐ and ionization‐ potentials evolution upon batteries cycling. The approach enables to forecast the intrinsic stability of the cathodes and discriminate the reaction pathways associated with interfacial electronic charge‐transfer mechanisms. Specifically, light is shed on the evolution of cationic and anionic redox in high‐energy density lithium‐rich 0.33Li₂MnO₃·0.67LiNi₀.₄Co₀.₂Mn₀.₄O₂ (HE‐NCM) cathodes, particularly those that undergo surface modification through SO₂ and NH₃ double‐gas treatment to suppress the structural degradation. The chemical composition and energy distribution of the occupied and unoccupied electronic states at the different charging/discharging states are quantitatively estimated by using advanced spectroscopy techniques, including operando Raman spectroscopy. The concept is successfully demonstrated in designing artificial interfaces for high‐voltage olivine structure cathodes enabling stable battery operation up to 5.1 V versus Li⁺/Li
Phänomenologische Betrachtung des elektrischen Verhaltens schrägverzahnter Stirnräder zur Identifikation sensorisch nutzbarer Effekte
Get PDFDie Zustandsüberwachung von Getrieben und Maschinenelementen, wie z. B. Verzahnungen, gewinnt mit der fortschreitenden Digitalisierung zunehmend an Bedeutung. Für präzise Steuerungs- und Regelungsanwendungen sowie die Überwachung von Betriebszuständen werden zuverlässige Zustandsinformationen benötigt. Diese benötigten Zustandsinformationen werden durch sensorische Funktionen erfasst und einer Informationsverarbeitung zugeführt. Bei großen Distanzen oder komplexen Übertragungspfaden zwischen Mess- und Interessensort wird von ex-situ-Messungen gesprochen, die eine höhere Störan-fälligkeit und einen erhöhten Auswerteaufwand mit sich bringen. Ziel aktueller Forschungsvorhaben ist es, sensorische Funktionen unmittelbar am Interessensort zu integrieren, um die Vorteile einer sogenannten in-situ-Messung zu erschließen.
In der aktuellen Forschung sowie ersten praktischen Anwendungen wird das Konzept sensorisch nutzbarer Maschinenelemente (engl. Sensory utilizable Machine Elements, SuME) untersucht bzw. umgesetzt. Dabei werden physikalische Effekte in Maschinenelementen sensorisch genutzt, wie z. B. die elektrischen Eigenschaften tribologischer Kontakte in Wälzlagern zur Überwachung von Belastungen und Schadenszuständen. Auch für Verzahnungen wird an der Integration sensorischer Funktionen geforscht, wobei die Nutzung der elektrischen Eigenschaften des Zahnkontakts bislang nicht im Fokus stehen.
Die vorliegende Arbeit untersucht die Potentiale und Grenzen einer sensorischen Nutzung der elektrischen Eigenschaften des Zahnkontakts zwischen schrägverzahnten Stirnrädern. Hierfür werden zwei geometrisch verschiedene Verzahnungen systematisch in verschiedenen Betriebspunkten mittels elektrischer Impedanzanalyse untersucht. Die Ergebnisse zeigen, dass die vorherrschenden Schmierungszustände im Zahnkontakt identifiziert und quantitativ beschrieben werden können: Während der Grenzflächenreibung zeigt sich ein resistives elektrisches Verhalten, das über die Mischreibung hin zur Flüssigkeitsreibung in ein kapazitives Verhalten übergeht. Drehzahl, Drehmoment und Schmierstofftemperatur beeinflussen die elektrischen Eigenschaften ebenfalls in signifikantem Maß. Zudem zeigt das elektrische Impedanzsignal des Zahnkontakts zwischen schrägverzahnten Stirnrädern einen charakteristischen Verzahnungsabdruck, der Informationen zur Eingriffsstrecke, zu herstellungsbedingten Teilungsabweichungen sowie zu künstlich aufgebrachten Oberflächenveränderungen liefert.
Die Arbeit verdeutlicht das Potential der elektrischen Impedanzanalyse für die Zustandsüberwachung von schrägverzahnten Stirnrädern. Das Messverfahren erlaubt die unmittelbare sensorische Erfassung von Zustandsinformationen im Zahnkontakt während des Betriebs und kann die Weiterentwicklung und die Optimierung von Getrieben und Verzahnungen unterstützen. Grenzen des Messverfahrens ergeben sich jedoch durch die elektrisch parallele Erfassung mehrerer Zahnkontakte aufgrund einer hohen Überdeckung der Zahneingriffe sowie durch die noch fehlenden elektrischen Modelle des Zahnkontakts zwischen schrägverzahnten Stirnrädern. Damit zeigt die vorliegende Arbeit die umfassenden Potentiale einer elektrischen Impedanzanalyse im Rahmen der Zustandsüberwachung von schrägverzahnten Stirnrädern auf und bietet Impulse für nachfolgende Forschungsarbeiten