Search results for "Operation"
showing 10 items of 2969 documents
On the numerical scheme employed in gyrotron interaction simulations
2012
We report on the influence of the numerical scheme employed in gyrotron interaction simulations. Results obtained with the Crank-Nicolson scheme are compared with those obtained with the Backward Time – Centred Space (BTCS) fully implicit scheme. We present realistic cases where, for discretisation parameters in the range usually used in gyrotron simulations, the results can be very different. Hence, the numerical scheme used can be responsible for obscuring the underlying physics if its convergence is not tested carefully.
Sub-kelvin current amplifier using DC-SQUID
2000
Abstract We have set up a system where a low-noise DC-SQUID is used as a current amplifier. The SQUID output is read using a wide band electronics unit based on the noise cancellation scheme. The SQUID has been installed in a compact Nanoway PDR50 dilution refrigerator, and superconducting transitions of Ti/Au thermometer strips for X-ray calorimeter applications have been measured. We can operate at 100 mK using a SQUID with Pd shunt resistors. Noise and bandwidth results of the setup are presented.
Symmetry of molecular properties
1993
The symmetry of coefficients in the expansion of a given molecular property are shown to be obtainable through well defined tensor methods. The analytical expansions required of various vibrational and rotational tensors are given up to the fourth degree in dynamical variables. To illustrate the method, some rovibrational properties of spherical tops are considered. The symmetry of the associated molecular constants is expressed, simultaneously, for XY4 and XY6 molecules, by algebraic relations involving the independent constants and the coupling symbols of the molecular symmetry group. To allow comparisons, some examples are given for which the symmetry of the constants has been published …
N-string vertices in string field theory.
1993
We give the general form of the vertex corresponding to the interaction of an arbitrary number of strings. The technique employed relies on the ``comma" representation of String Field Theory where string fields and interactions are represented as matrices and operations between them such as multiplication and trace. The general formulation presented here shows that the interaction vertex of N strings, for any arbitrary N, is given as a function of particular combinations of matrices corresponding to the change of representation between the full string and the half string degrees of freedom.
Reduced dynamical equations for solid-state lasers and VCSELs
2007
It is the aim of this presentation to show that a reduction in the number of coupled equations is feasible for spatio-temporal laser models with generic values of the pump and other parameters. Reduced equations have been derived via the application of two separate, yet equivalent, methods: one based on the CM and the other on operational calculus. The long term dynamics of the reduced models for solid-state lasers and VCSELs have been compared with that of the full systems by using both mathematical methods. Extensive numerical simulations for the complex dynamics of these and other laser models become suddenly feasible within reasonable computational time.
Switching quantum memory on and off
2015
Modifying the Markovian (memoryless) or non-Markovian (memory-keeping) nature of the environment-induced evolution of an open quantum system is crucial in quantum information theory, because it is linked to quantum memory control. A recent work (Brito and Werlang 2015 New J. Phys. 17 072001) shows that such a goal can be achieved without operating on unaccessible environmental features. In fact, transitions between Markovian and non-Markovian regimes of a qubit dynamics can be induced on demand if the qubit is coupled to a controlled auxiliary system. This is a step towards the improvement of quantum devices, aiming at exploiting dynamical memory effects by an external control.
Reconstruction of events recorded with the surface detector of the Pierre Auger Observatory
2020
Cosmic rays arriving at Earth collide with the upper parts of the atmosphere, thereby inducing extensive air showers. When secondary particles from the cascade arrive at the ground, they are measured by surface detector arrays. We describe the methods applied to the measurements of the surface detector of the Pierre Auger Observatory to reconstruct events with zenith angles less than 60 using the timing and signal information recorded using the water-Cherenkov detector stations. In addition, we assess the accuracy of these methods in reconstructing the arrival directions of the primary cosmic ray particles and the sizes of the induced showers.
Models and solution methods for the uncapacitatedr-allocationp-hub equitable center problem
2017
Hub networks are commonly used in telecommunications and logistics to connect origins to destinations in situations where a direct connection between each origin–destination (o-d) pair is impractical or too costly. Hubs serve as switching points to consolidate and route traffic in order to realize economies of scale. The main decisions associated with hub-network problems include (1) determining the number of hubs (p), (2) selecting the p-nodes in the network that will serve as hubs, (3) allocating non-hub nodes (terminals) to up to r-hubs, and (4) routing the pairwise o-d traffic. Typically, hub location problems include all four decisions while hub allocation problems assume that the valu…
Vecāku un skolotāju sadarbošanās veidi pirmsskolas izglītības pilnveidē
2021
Kvalifikācijas darbs izstrādāts par tēmu: “Vecāku un skolotāju sadarbošanās veidi pirmsskolas izglītības pilnveidē.” Darba autore: Inga Zača Darba vadītājs: Guna Svence Darba mērķis: Izpētīt pirmsskolas izglītības iestādes sadarbību veidus ar vecākiem. Izpētīt vecāku aktivitāti/ieinteresētību pirmsskolas izglītības iestādes pilnveidē. Darba struktūra: Kvalifikācijas darbs sastāv no divām daļām – teorētiskās un empīriskās daļas. Darba pirmā daļa sniedz priekšstatus par pedagoģiskās sadarbības jēdzienu vispārīgi, par sadarbības metodēm un formām, kā arī par iespējamām pedagoģiskām barjerām. Darba otrajā, empīriskajā daļā tiek atspoguļoti vecāku uzskati par sadarbību ar pirmskolas iestādi, vei…
On the hardness of evaluating criticality of activities in a planar network with duration intervals
2003
Complexity results for problems of evaluating the criticality of activities in planar networks with duration time intervals are presented. We show that the problems of asserting whether an activity is possibly critical, and of computing bounds on the float of an activity in these networks are NP-complete and NP-hard, respectively.