1,002 research outputs found

    Lipschitz geometry of complex surfaces: analytic invariants and equisingularity

    Full text link
    We prove that the outer Lipschitz geometry of a germ (X,0)(X,0) of a normal complex surface singularity determines a large amount of its analytic structure. In particular, it follows that any analytic family of normal surface singularities with constant Lipschitz geometry is Zariski equisingular. We also prove a strong converse for families of normal complex hypersurface singularities in C3\mathbb C^3: Zariski equisingularity implies Lipschitz triviality. So for such a family Lipschitz triviality, constant Lipschitz geometry and Zariski equisingularity are equivalent to each other.Comment: Added a new section 10 to correct a minor gap and simplify some argument

    Strong field QED in lepton colliders and electron/laser interactions

    Get PDF
    Studies of strong field particle physics processes in electron/laser interactions and lepton collider interaction points are reviewed. These processes are defined by the high intensity of the electromagnetic fields involved and the need to take them into account as fully as possible. The main theoretical framework considered is the Furry picture. In this framework, the influence of a background electromagnetic field in the Lagrangian is calculated non perturbatively, involving exact solutions for quantised charged particles in the background field. These "dressed" particles go on to interact perturbatively with other particles. The background field starts to polarise the vacuum, in effect rendering it a dispersive medium. Particles encountering this dispersive vacuum obtain a lifetime, either radiating or decaying into pair particles at a rate dependent on the intensity of the background field. In fact, the intensity of the background field enters into the coupling constant of the strong field QED Lagrangian, influencing all particle processes. A number of new phenomena occur. Particles gain an intensity dependent rest mass shift that accounts for their presence in the dispersive vacuum. Multi photon events involving more than one external field photon occur at each vertex. Higher order processes which exchange a virtual strong field particle, resonate via the lifetimes of the unstable strong field states. Two main arenas of strong field physics are reviewed; those occurring in relativistic electron interactions with intense laser beams, and those occurring in the beam beam physics at the interaction point of colliders. This review outlines the theory, describes its significant novel phenomenology and details the experimental schema required to detect strong field effects and the simulation programs required to model them.Comment: Review article, 56 pages, 29 figures. Version 2 has corrected errata, 1 new reference, 5 updated figure

    Solution-Processed Perovskite Photodetectors

    Get PDF
    Photodetectors enable conversion from light signals to electrical signals and are widely used in both the civil and military field for applications such as missile guidance, optical communication, imaging and biomedical sensing. Although various semiconductors have been employed in photodetectors, their high cost and complexity of fabrication have hindered their further development. Recently, perovskites have attracted substantial interest due to their impressive optoelectronic properties, including tuneable bandgaps, large absorption coefficient, long diffusion length and high carrier mobility. However, perovskites are generally not stable when exposed to ambient air, which seriously degrades the device performance. In this thesis, all-inorganic perovskite quantum dot (QD)-based photodetectors are investigated to enhance the material quality, device photoresponse and environmental stability. Three efficient strategies are developed to optimise the material film morphology and optical properties, as well as light confinement. I also managed to develop perovskite QD detectors on flexible substrates. Firstly, caesium lead bromide (CsPbBr3) QDs were optimised by blending ZnO nanoparticles (NPs), and further employed in a heterostructured photodetector. The as-fabricated device exhibited an improved photoresponse, including a 10-fold improved responsivity (0.4 mA W-1) and a short response time of 73.5 ms, as well as an excellent air stability (~ 7 month) due to the enhanced film morphology and optical properties after the decoration of ZnO NPs. Secondly, CsBr/KBr additives and a photovoltaic architecture were developed to further boost the device performance. An enhanced surface morphology and crystal quality with reduced defects were achieved by CsBr/KBr mediation. The resulting flexible photodetectors exhibited a better photoresponse, good flexibility and outstanding electrical stability. Specifically, this optimized photodetector showed a high responsivity of 10.1 A W-1, a large detectivity approaching 1014 Jones, and an on/off ratio around 104. In addition to the material optimisations, anodic aluminium oxide plasmonic structures were adopted with control of geometry and decoration of metallic NPs in the perovskite photodetectors, which enabled efficient light transmission and collection, and resulted in a 40-fold enhancement in device photoresponse. In the future, I will continue to focus on material and structural optimisations to develop high-performance and stable optoelectronics. In addition, perovskite-based focal plane arrays have great potential to be investigated

    Book reports

    Get PDF

    Dust control handbook for industrial minerals mining and processing

    Get PDF
    Throughout the mining and processing of minerals, the mined ore undergoes a number of crushing, grinding, cleaning, drying, and product sizing operations as it is processed into a marketable commodity. These operations are highly mechanized, and both individually and collectively these processes can generate large amounts of dust. If control technologies are inadequate, hazardous levels of respirable dust may be liberated into the work environment, potentially exposing workers. Accordingly, federal regulations are in place to limit the respirable dust exposure of mine workers. Engineering controls are implemented in mining operations in an effort to reduce dust generation and limit worker exposure.NIOSHTIC no. 2004022

    Proceedings of FORM 2022. Construction The Formation of Living Environment

    Get PDF
    This study examines the integration of building information modelling (BIM) technologies in operation & maintenance stage in the system of managing real estate that helps to reduce transaction costs. The approach and method are based on Digital Twin technology and Model Based System Engineering (MBSE) approach. The results of the development of a service for digital facility management and digital expertise are presented. The connection between physical and digital objects is conceptualized
    • …
    corecore