1,002 research outputs found
Lipschitz geometry of complex surfaces: analytic invariants and equisingularity
We prove that the outer Lipschitz geometry of a germ 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 : 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
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
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
Dust control handbook for industrial minerals mining and processing
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
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
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