https://biblio.ugent.be/publication/685594/file/1130605.pdf

Review of Particle Physics

The Pythia program can be used to generate high-energy-physics ''events'', i.e. sets of outgoing particles produced in the interactions between two incoming particles. The objective is to provide as accurate as possible a representation of event properties in a wide range of reactions, within and beyond the Standard Model, with emphasis on those where strong interactions play a role, directly or indirectly, and therefore multihadronic final states are produced. The physics is then not understood well enough to give an exact description; instead the program has to be based on a combination of analytical results and various QCD-based models. This physics input is summarized here, for areas such as hard subprocesses, initial- and final-state parton showers, underlying events and beam remnants, fragmentation and decays, and much more. Furthermore, extensive information is provided on all program elements: subroutines and functions, switches and parameters, and particle and process data. This should allow the user to tailor the generation task to the topics of interest.

/pdf/pythia-6-4-physics-and-manual-3dvwmijpnq.pdf

PYTHIA 6.4 Physics and Manual

We review the field of cavity optomechanics, which explores the interaction between electromagnetic radiation and nano- or micromechanical motion This review covers the basics of optical cavities and mechanical resonators, their mutual optomechanical interaction mediated by the radiation pressure force, the large variety of experimental systems which exhibit this interaction, optical measurements of mechanical motion, dynamical backaction amplification and cooling, nonlinear dynamics, multimode optomechanics, and proposals for future cavity quantum optomechanics experiments In addition, we describe the perspectives for fundamental quantum physics and for possible applications of optomechanical devices

Cavity Optomechanics

Bose-Einstein condensation (BEC) has been observed in a dilute gas of sodium atoms. A Bose-Einstein condensate consists of a macroscopic population of the ground state of the system, and is a coherent state of matter. In an ideal gas, this phase transition is purely quantum-statistical. The study of BEC in weakly interacting systems which can be controlled and observed with precision holds the promise of revealing new macroscopic quantum phenomena that can be understood from first principles.

Bose-Einstein condensation in a gas of sodium atoms

Topological photonics is a rapidly emerging field of research in which geometrical and topological ideas are exploited to design and control the behavior of light. Drawing inspiration from the discovery of the quantum Hall effects and topological insulators in condensed matter, recent advances have shown how to engineer analogous effects also for photons, leading to remarkable phenomena such as the robust unidirectional propagation of light, which hold great promise for applications. Thanks to the flexibility and diversity of photonics systems, this field is also opening up new opportunities to realize exotic topological models and to probe and exploit topological effects in new ways. This article reviews experimental and theoretical developments in topological photonics across a wide range of experimental platforms, including photonic crystals, waveguides, metamaterials, cavities, optomechanics, silicon photonics, and circuit QED. A discussion of how changing the dimensionality and symmetries of photonics systems has allowed for the realization of different topological phases is offered, and progress in understanding the interplay of topology with non-Hermitian effects, such as dissipation, is reviewed. As an exciting perspective, topological photonics can be combined with optical nonlinearities, leading toward new collective phenomena and novel strongly correlated states of light, such as an analog of the fractional quantum Hall effect.

Topological Photonics

In this study, the test performance of high-resolution digital off-axis holography for the non-spherical droplet characteristics and spatial distribution in the primary breakup region of a pressure-swirl nozzle were experimentally investigated, with spatial resolution of 4.5μm and 3.0μm. The field of interest (FOI) was restricted within 9 mm downstream of the nozzle outlet, where the primary and some secondary breakup processes take place. The liquid investigated here is RP-3 kerosene, and the injection pressure and liquid temperature were controlled in the range of 0.5 ∼ 1.0 MPa and 250 ∼ 291 K separately. Clear spray morphology and deformed droplet image were obtained through the holographic reconstruction process. Droplet extraction criteria were proposed to distinguish deformed droplets from ligaments. The overall drop size and ellipticity distribution were quantified and discussed. The results show that the overall drop size distributions near the nozzle are also typical single-peaked curves. The proportions of non-spherical droplet increase as the fuel pressure and temperature increase. The spatial Sauter mean diameter (SMD) distributions of spray at different positions downstream of the nozzle were calculated, with the grid size of 1 × 1 × 1 mm3, showing the doughnut-like annular SMD and droplet number distribution profiles of the hollow conical spray. As the temperature and fuel pressure decrease, SMD distribution becomes uneven and larger. Fine droplets exist in the region where the perforation and primary breakup process occur, and the SMD increases over the axial distance due to the breakup process of ligaments near the nozzle. Results also prove that digital off-axis holography presented here is expected to realize the 3D viewing of the conical liquid sheet and statistical quantification of the droplet where primary and secondary breakup processes mainly occurred. 

Conical liquid sheet morphology and 3D droplet distribution of aviation kerosene pressure-swirl spray with digital off-axis holography

Process data in contemporary thermal power plants shows the characteristics of large capacity, strong coupling, and high-order nonlinearity, which brings great challenges to process monitoring and fault detection. A deep representation learning fault detection scheme based on stacked sparse denoising autoencoder (SSDAE) is proposed in this paper. Specifically, to enhance the capabilities of noise reduction and feature representation for complex industrial data, the sparse denoising autoencoder (SDAE) is proposed by considering both noise and sparsity constraints. Then, a deep learning architecture is constructed by stacking multiple SDAEs layer by layer to achieve a highly nonlinear representation capability. Based on the low-dimensional representation and residual distance of SSDAE, three monitoring indicators, RE2, MD2, and ZD2, are designed by different distance metrics and the k-nearest neighbor (KNN) discriminant rule. The effectiveness of the proposed method is validated by studying a nonlinear numerical case and a practical power plant pulverizing system. The experimental results demonstrate that the proposed method can effectively detect incipient and slight faults that are difficult to detect with traditional methods.

Incipient fault detection and process monitoring of thermal power plant pulverizing system based on deep representation learning

Lithium-ion batteries (LIBs) thermal safety issues such as thermal runaway (TR) triggered by thermal or mechanical abuse have been one of the most important factors hindering its development at present. In order to effectively release the excessive pressure caused by TR, a safety vent is used as a reliable safety device in commercial LIBs. However, the current interrupt device (CID) and vent activation behaviour and mechanism are still unclear in the mesoscale. Herein, finite element simulations of metallic material deformation and failure during CID and vent activation at preset dynamic incremental pressure loads and various constant temperatures for a commercial 18650 LIB were carried out by introducing the Johnson-Cook (J-C) damage model in this study. The three-dimensional evolution, dynamical and mechanical analysis of the deformation to damage behaviour are quantitatively characterized. The CID- and vent-activation pressure based on the J-C damage criterion is significantly higher than the pressure value corresponding to the maximum von Mises stress. The results show fracture strain of the burst disk notch and plate will not exceed 0.93 % and 0.048 % respectively when the TR reaches the onset temperature. The temperature-dependent activation time reduction rate was developed to quantify the effect of temperature on the CID-and vent-activation times, indicating that TR temperature's effect on vent activation is significantly stronger than that of CID. These results may provide a reliable guide to LIB safety design. 

Ying Wu

Papers

Conical liquid sheet morphology and 3D droplet distribution of aviation kerosene pressure-swirl spray with digital off-axis holography

Incipient fault detection and process monitoring of thermal power plant pulverizing system based on deep representation learning

Thermal runaway-induced current interrupt device and vent activation behaviour in an 18650 lithium-ion battery cap using the Johnson-Cook criterion