133 research outputs found
OZM Ball Drop Impact Tester (BIT‐132) vs. BAM Standard Method – a Comparative Investigation
Safety, performance, cost efficient synthesis and toxicity are the most important aspects of modern explosives. Sensitivity measurements are performed in accordance with different protocols all around the world. Sometimes the BAM drop hammer does not accurately reflect the sensitivity of an energetic material, in particular the sensitivity of primary explosives. Therefore, we present here preliminary results obtained using the novel ball drop tester (BIT‐132), manufactured by OZM research, following MIL‐STD‐1751 A (method 1016). The ball drop impact sensitivity tester is a device in which a free‐falling steel ball is dropped onto an unconfined sample, and is expected to produce more realistic results than the currently commonly used BAM method. The results obtained using the probit analysis were compared to those from the BAM drop hammer and friction tester. The following sensitive explosives were investigated: HMTD, TATP, TAT, Tetrazene, MTX‐1, KDNBF, KDNP, K2DNABT, Lead Styphnate Monohydrate, DBX‐1, Nickel(II) Hydrazine Nitrate, Silver Acetylide, AgN3, Pb(N3)2 RD‐1333, AgCNO, and Hg(CNO)2
Higher-dimensional multifractal value sets for conformal infinite graph directed Markov systems
We give a description of the level sets in the higher dimensional
multifractal formalism for infinite conformal graph directed Markov systems. If
these systems possess a certain degree of regularity this description is
complete in the sense that we identify all values with non-empty level sets and
determine their Hausdorff dimension. This result is also partially new for the
finite alphabet case.Comment: 20 pages, 1 figur
Bifurcations in the Space of Exponential Maps
This article investigates the parameter space of the exponential family
. We prove that the boundary (in \C) of every
hyperbolic component is a Jordan arc, as conjectured by Eremenko and Lyubich as
well as Baker and Rippon. In fact, we prove the stronger statement that the
exponential bifurcation locus is connected in \C, which is an analog of
Douady and Hubbard's celebrated theorem that the Mandelbrot set is connected.
We show furthermore that is not accessible through any nonhyperbolic
("queer") stable component.
The main part of the argument consists of demonstrating a general "Squeezing
Lemma", which controls the structure of parameter space near infinity. We also
prove a second conjecture of Eremenko and Lyubich concerning bifurcation trees
of hyperbolic components.Comment: 29 pages, 3 figures. The main change in the new version is the
introduction of Theorem 1.1 on the connectivity of the bifurcation locus,
which follows from the results of the original version but was not explicitly
stated. Also, some small revisions have been made and references update
Complex maps without invariant densities
We consider complex polynomials for and
, and find some combinatorial types and values of such that
there is no invariant probability measure equivalent to conformal measure on
the Julia set. This holds for particular Fibonacci-like and Feigenbaum
combinatorial types when sufficiently large and also for a class of
`long-branched' maps of any critical order.Comment: Typos corrected, minor changes, principally to Section
Rigidity of escaping dynamics for transcendental entire functions
We prove an analog of Boettcher's theorem for transcendental entire functions
in the Eremenko-Lyubich class B. More precisely, let f and g be entire
functions with bounded sets of singular values and suppose that f and g belong
to the same parameter space (i.e., are *quasiconformally equivalent* in the
sense of Eremenko and Lyubich). Then f and g are conjugate when restricted to
the set of points which remain in some sufficiently small neighborhood of
infinity under iteration. Furthermore, this conjugacy extends to a
quasiconformal self-map of the plane.
We also prove that this conjugacy is essentially unique. In particular, we
show that an Eremenko-Lyubich class function f has no invariant line fields on
its escaping set.
Finally, we show that any two hyperbolic Eremenko-Lyubich class functions f
and g which belong to the same parameter space are conjugate on their sets of
escaping points.Comment: 28 pages; 2 figures. Final version (October 2008). Various
modificiations were made, including the introduction of Proposition 3.6,
which was not formally stated previously, and the inclusion of a new figure.
No major changes otherwis
Assessment and prevalence of depression in women 45–55 years of age visiting gynecological clinics in Poland
¶The aims of the Polish survey were to assess efficacy of screening for depression in gynecological practice and to estimate prevalence of depressive disorders in midlife women visiting gynecologists. The study included 2262 female outpatients aged 45–55, who were screened by 120 gynecologists throughout Poland. Patients completed the Beck’s Depression Inventory (BDI) and were assessed by gynecologists to verify the presence of symptoms of a current Depressive Episode according to ICD-10 diagnostic criteria. Patients who obtained a score of 12 points or more on the BDI were referred for psychiatric evaluation, including the modified version of Mini International Neuropsychiatric Interview (MINI). The study showed that gynecologists in Poland are able to perform screenings for depression effectively in outpatient settings. Results also suggested that about 19% of women aged 45 to 55 years visiting gynecologists may suffer from depressive disorders.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/41736/1/737_2003_Article_019.pd
Thermodynamic formalism for contracting Lorenz flows
We study the expansion properties of the contracting Lorenz flow introduced
by Rovella via thermodynamic formalism. Specifically, we prove the existence of
an equilibrium state for the natural potential for the contracting Lorenz flow and for in an interval
containing . We also analyse the Lyapunov spectrum of the flow in terms
of the pressure
Set-valued orthogonal additivity
We study the set-valued Cauchy equation postulated for orthogonal vectors. We give its general solution as well as we look for selections of functions satisfying the equation
The Hausdorff and dynamical dimensions of self-affine sponges : a dimension gap result
We construct a self-affine sponge in R 3 whose dynamical dimension, i.e. the supremum of the Hausdorff dimensions of its invariant measures, is strictly less than its Hausdorff dimension. This resolves a long-standing open problem in the dimension theory of dynamical systems, namely whether every expanding repeller has an ergodic invariant measure of full Hausdorff dimension. More generally we compute the Hausdorff and dynamical dimensions of a large class of self-affine sponges, a problem that previous techniques could only solve in two dimensions. The Hausdorff and dynamical dimensions depend continuously on the iterated function system defining the sponge, implying that sponges with a dimension gap represent a nonempty open subset of the parameter space
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