2,881 research outputs found
Gas Seal Pad With Herringbone-Grooved Rotor-Stiffness and Load Capacity
The principle of herringbone-grooved journal bearings has been applied to the case of a seal disc running under a finger seal pad. The inward pumping action of herringbone grooves on the disc generates load capacity and stiffness to maintain a fluid film and prevent contact of the pad and disc. This mechanism does not depend on a converging film under the pad, such as analyzed in previous works. Analysis shows that significant stiffness and load capacity can be supplied by herringbone grooves. In order for the grooves to be effective, the seal pressure drop must be taken outside of the grooved portion of the rotor, but this may be acceptable in order to gain freedom from maintaining a precise film convergence
Convergence rates in expectation for Tikhonov-type regularization of Inverse Problems with Poisson data
In this paper we study a Tikhonov-type method for ill-posed nonlinear
operator equations \gdag = F(
ag) where \gdag is an integrable,
non-negative function. We assume that data are drawn from a Poisson process
with density t\gdag where may be interpreted as an exposure time. Such
problems occur in many photonic imaging applications including positron
emission tomography, confocal fluorescence microscopy, astronomic observations,
and phase retrieval problems in optics. Our approach uses a
Kullback-Leibler-type data fidelity functional and allows for general convex
penalty terms. We prove convergence rates of the expectation of the
reconstruction error under a variational source condition as both
for an a priori and for a Lepski{\u\i}-type parameter choice rule
"Зелена" покрівля, як елемент захисту будинків
Розвиток міст на сучасному етапі потребує рішення низки проблем, пов'язаних з необхідністю будівництва обєктів у складних геомеханічних умовах [1], зсувонебезпечних територіях [2], реконструкцією житла, забезпечення енерго та ресурсоефективності будівель та споруд, тощо
Interference-filter-stabilized external-cavity diode lasers
We have developed external-cavity diode lasers, where the wavelength
selection is assured by a low loss interference filter instead of the common
diffraction grating. The filter allows a linear cavity design reducing the
sensitivity of the wavelength and the external cavity feedback against
misalignment. By separating the feedback and wavelength selection functions,
both can be optimized independently leading to an increased tunability of the
laser. The design is employed for the generation of laser light at 698, 780 and
852 nm. Its characteristics make it a well suited candidate for space-born
lasers.Comment: 12 pages, 5 figure
In the Interests of clients or commerce? Legal aid, supply, demand, and 'ethical indeterminacy' in criminal defence work
As a professional, a lawyer's first duty is to serve the client's best interests, before simple monetary gain. In criminal defence work, this duty has been questioned in the debate about the causes of growth in legal aid spending: is it driven by lawyers (suppliers) inducing unnecessary demand for their services or are they merely responding to increased demand? Research reported here found clear evidence of a change in the handling of cases in response to new payment structures, though in ways unexpected by the policy's proponents. The paper develops the concept of 'ethical indeterminacy' as a way of understanding how defence lawyers seek to reconcile the interests of commerce and clients. Ethical indeterminacy suggests that where different courses of action could each be said to benefit the client, the lawyer will tend to advise the client to decide in the lawyer's own interests. Ethical indeterminacy is mediated by a range of competing conceptions of 'quality' and 'need'. The paper goes on to question the very distinction between 'supply' and 'demand' in the provision of legal services
Necessary conditions for variational regularization schemes
We study variational regularization methods in a general framework, more
precisely those methods that use a discrepancy and a regularization functional.
While several sets of sufficient conditions are known to obtain a
regularization method, we start with an investigation of the converse question:
How could necessary conditions for a variational method to provide a
regularization method look like? To this end, we formalize the notion of a
variational scheme and start with comparison of three different instances of
variational methods. Then we focus on the data space model and investigate the
role and interplay of the topological structure, the convergence notion and the
discrepancy functional. Especially, we deduce necessary conditions for the
discrepancy functional to fulfill usual continuity assumptions. The results are
applied to discrepancy functionals given by Bregman distances and especially to
the Kullback-Leibler divergence.Comment: To appear in Inverse Problem
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