Study on the characteristics of gas permeability of coal under loaded stress

The #3 coal seam of Jinsheng Rundong Ltd. of Jin-Coal Group in Shanxi Province, China, has high gas content and pressure; however, it has a low gas permeability, which can easily cause gas enrichment and may cause accidents of coal and gas outbursts. In this work, the characteristics of gas seepage were thoroughly studied by designing and modifying the ‘complete stress-strain tri-axial servo temperature-controlled test system’. The study was conducted based on four factors: Axial pressure, confining pressure, effective stress and gas pressure. We found that the axial pressure has a weak impact on coal gas permeability, indicated by a linear relationship. The confining pressure, however, has a strong impact on gas permeability, showing an exponential relationship. The relationship between permeability and gas pressure was identified as a second-order polynomial function. The functional relationship between gas permeability and axial pressure, confining pressure, effective stress, gas pressure was analyzed. Investigation into the natural flow rate of gas, concentration of gas drainage and damping coefficient supported the conclusion from the experimental study on the characteristics of gas seepage under loaded stress

Non-Hermitian Kibble-Zurek mechanism with tunable complexity in single-photon interferometry

Non-Hermitian descriptions of quantum matter have seen impressive progress recently, with major advances in understanding central aspects such as their topological properties or the physics of exceptional points, the non-Hermitian counterpart of critical points. Here, we use single-photon interferometry to reconstruct the non-Hermitian Kibble-Zurek mechanism and its distinct scaling behavior for exceptional points, by simulating the defect production upon performing slow parameter ramps. Importantly, we are able to realise also higher-order exceptional points, providing experimental access to their theoretically predicted characteristic Kibble-Zurek scaling behaviour. Our work represents a crucial step in increasing the experimental complexity of non-Hermitian quantum time-evolution. It thus also furthers the quest to move the frontier from purely single-particle physics towards increasingly complex settings in the many-body realm.Comment: 8 pages, 6 figure

Demonstration of a photonic router via quantum walks

Motivated by the need for quantum computers to communicate between multiple, well separated qubits, we introduce the task of routing the quantum state from one input mode to a superposition of several output modes coherently. We report an experimental demonstration of a deterministic photonic routing protocol applied to an entangled state. We show in a quantum walk architecture, quantum networks perfectly route entangled states from an initial input mode to an arbitrary output mode coherently and deterministically. Our results demonstrate the key principle of a perfect router, opening a route toward data routing and transferring for quantum computing systems. The routing algorithm in our work can be applied to a wide range of physical systems, which provides a way for effective design of efficient routing protocols on practical quantum networks

Experimental verification of trade-off relation for coherence and disturbance

When a quantum system is sent through a noisy channel, it is usually disturbed. At the same time, the system undergoes decoherence and tends to lose some delicate quantum features. For a particular basis, the coherence of the state changes. Otherwise, if the system is not disturbed, its state might retain all of coherence. As quantum noisy channels lead to both disturbance and decoherence, it is natural to ask about the relation between disturbance and decoherence. Recently, a trade-off relation for coherence and disturbance has been presented by Sharma and Pati (2018 Phys. Rev. A 97 062308). In this paper, with entangled photon pairs and linear optics, we experimentally verify this trade-off relation for a single-qubit system undergoing various noisy channels. Our experimental results agree with the theoretical predictions and provide a quantitative understanding of the relation between quantum channels and resources

Influence of Dimple Diameter and Depth on Heat Transfer of Impingement-Cooled Turbine Leading Edge with Cross-Flow and Dimple

Today, impingement cooling structures with dimples can effectively ease the burden of turbine blades. This paper investigates the effect of dimple diameter and depth on the heat transfer of the target surface on a laminar-cooled turbine blade with a cross-flow and dimple numerically to find the mechanism behind it so that the dimple can be better used in turbine cooling. The commercial software ANSYS 19.2 and a baseline (BSL) turbulence model is used during the numerical computation. In this paper, the cross-flow Reynolds number varies from 15,000 to 60,000, while the jet Reynolds number remains at 30,000. When the cross-flow Reynolds number changes, due to the location change in vortexes generated inside or around the dimple, the two dimple parameters affect heat transfer differently. When the cross-flow Reynolds number is lower than the jet Reynolds number, dimples with smaller diameters and depths lead to better heat transfer performance. When the cross-flow Reynolds number exceeds the jet Reynolds number, dimples with bigger diameters and depths result in better heat exchange performance. The results also indicate that, while the dimple diameters remain constant, the rise of the cross-flow Reynolds number enhances the heat transfer of the dimple structure