21,778 research outputs found
Experimental investigations of solid nitrogen formed by cryopumping
Density, thermoconductivity, and sticking coefficient of nitrogen condensate formed on cryopum
Impact pressure probe response characteristics in high speed flows, with transition Knudsen numbers
Impact pressure probe response characteristics in free-molecular and continuum flows with transition Knudsen number
Impact pressure probe reponse characteristics in high speed flows with transition knudsen numbers
Impact pressure probe response characteristics in high speed flows with transition Knudsen number
<i>H</i><sub>2</sub> and mixed <i>H</i><sub>2</sub>/<i>H</i><sub>∞</sub> Stabilization and Disturbance Attenuation for Differential Linear Repetitive Processes
Repetitive processes are a distinct class of two-dimensional systems (i.e., information propagation in two independent directions) of both systems theoretic and applications interest. A systems theory for them cannot be obtained by direct extension of existing techniques from standard (termed 1-D here) or, in many cases, two-dimensional (2-D) systems theory. Here, we give new results towards the development of such a theory in H2 and mixed H2/H∞ settings. These results are for the sub-class of so-called differential linear repetitive processes and focus on the fundamental problems of stabilization and disturbance attenuation
Control and Filtering for Discrete Linear Repetitive Processes with H infty and ell 2--ell infty Performance
Repetitive processes are characterized by a series of sweeps, termed passes, through a set of dynamics defined over a finite duration known as the pass length. On each pass an output, termed the pass profile, is produced which acts as a forcing function on, and hence contributes to, the dynamics of the next pass profile. This can lead to oscillations which increase in amplitude in the pass to pass direction and cannot be controlled by standard control laws. Here we give new results on the design of physically based control laws for the sub-class of so-called discrete linear repetitive processes which arise in applications areas such as iterative learning control. The main contribution is to show how control law design can be undertaken within the framework of a general robust filtering problem with guaranteed levels of performance. In particular, we develop algorithms for the design of an H? and dynamic output feedback controller and filter which guarantees that the resulting controlled (filtering error) process, respectively, is stable along the pass and has prescribed disturbance attenuation performance as measured by and – norms
Study of porous wall low density wind tunnel diffusers
Porous wall wind tunnel diffusers used with low density hypersonic nozzl
Assignment of the NV0 575 nm zero-phonon line in diamond to a 2E-2A2 transition
The time-averaged emission spectrum of single nitrogen-vacancy defects in
diamond gives zero-phonon lines of both the negative charge state at 637 nm
(1.945 eV) and the neutral charge state at 575 nm (2.156 eV). This occurs
through photo-conversion between the two charge states. Due to strain in the
diamond the zero-phonon lines are split and it is found that the splitting and
polarization of the two zero-phonon lines are the same. From this observation
and consideration of the electronic structure of the nitrogen-vacancy center it
is concluded that the excited state of the neutral center has A2 orbital
symmetry. The assignment of the 575 nm transition to a 2E - 2A2 transition has
not been established previously.Comment: 5 pages, 5 figure
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