1,027 research outputs found
THE RELIABILITY MODEL OF A SELECTED CLASS OF THE HIERARCHICAL SYSTEMS
The paper analyses digital systems a with three-level hierarchical structure. It has taken into
account reliability and functional aspects of the system. A reliability-functional model of the proposed
digital system has been presented
Demographic Trends and the Pension Problem in Poland
Projections of expenditures for old age pensions, survivor pensions, and disability pensions were made for the period 1985-2050 on the basis of future developments in population structure by age, sex, and marital status. Five demographic scenarios were formulated: (i) a Benchmark scenario, with demographic rates kept constant at their 1980-84 level; (ii) a Fertility scenario, with a decline of the Total Fertility Rate (TFR) towards replacement level; (iii) a Mortality scenario, with reductions in mortality rates of 30 percent for females, and 45 percent for males; (iv) a Western scenario, which combines extreme demographic conditions of several West European countries: a TFR of 1.28, proportions never-marrying of one-third, one-third of all marriages ending in divorce, and male and female life expectancies of 74 and 81 years, respectively; and (v) a National scenario, with a TFR declining to 1.6. Under all scenarios, the share of the elderly will rise, and that of children will diminish, with the most significant developments under the Western and the National scenarios.
Due to uncertain economic conditions in Poland, results of the pension model should be interpreted with great care. Yet, assuming no changes in the current pension system, the calculations point to a considerable growth in expenditures, ranging from some 65 percent (Benchmark and National scenario) to about 120 percent (Mortality scenario and Western scenario) for the period 1985-2050. The increase is particularly steep during the years 2000-2015. The ratio between contributions and benefits deteriorates from its current level of 1.13 to a ratio between 0.90 (Benchmark scenario) and 0.44 (Western scenario) in the year 2050
Mapping the spin-dependent electron reflectivity of Fe and Co ferromagnetic thin films
Spin Polarized Low Energy Electron Microscopy is used as a spin dependent
spectroscopic probe to study the spin dependent specular reflection of a
polarized electron beam from two different magnetic thin film systems:
Fe/W(110) and Co/W(110). The reflectivity and spin-dependent
exchange-scattering asymmetry are studied as a function of electron kinetic
energy and film thickness, as well as the time dependence. The largest value of
the figure of merit for spin polarimetry is observed for a 5 monolayer thick
film of Co/W(110) at an electron kinetic energy of 2eV. This value is 2 orders
of magnitude higher than previously obtained with state of the art Mini-Mott
polarimeter. We discuss implications of our results for the development of an
electron-spin-polarimeter using the exchange-interaction at low energy.Comment: 5 pages, 4 figure
Symbolic Extraction for Estimating Analog Layout Parasitics in Layout-Aware Synthesis
This paper presents a new layout parasitics extraction paradigm, symbolic extraction, for use in layout-aware analog synthesis methodologies. Unlike traditional post-layout extraction, symbolic extraction extracts layout parasitics in symbolic form from parameterized layouts. As a result, parasitic values can be calculated directly from given circuit and layout parameters. In layout-aware circuit synthesis process, tasks of time-consuming layout re-gerenarion and re-extraction can be replaced by this fast parasitics calculation step. In the paper, we discuss how to integrate symbolic extraction into the existing analog design flow and how symbolic extraction can be implemented
Bond stretching phonon softening and angle-resolved photoemission kinks in optimally doped Bi2Sr1.6La0.4Cu2O6 superconductors
We report the first measurement of the optical phonon dispersion in optimally
doped single layer Bi2Sr1.6La0.4Cu2O6+delta using inelastic x-ray scattering.
We found a strong softening of the Cu-O bond stretching phonon at about
q=(0.25,0,0) from 76 to 60 meV, similar to the one reported in other cuprates.
A direct comparison with angle-resolved photoemission spectroscopy measurements
taken on the same sample, revealed an excellent agreement in terms of energy
and momentum between the ARPES nodal kink and the soft part of the bond
stretching phonon. Indeed, we find that the momentum space where a 63 meV kink
is observed can be connected with a vector q=(xi,0,0) with xi~0.22, which
corresponds exactly to the soft part of the bond stretching phonon mode. This
result supports an interpretation of the ARPES kink in terms of electron-phonon
coupling.Comment: submited to PR
Instability of two dimensional graphene: Breaking sp2 bonds with soft X-rays
We study the stability of various kinds of graphene samples under soft X-ray
irradiation. Our results show that in single layer exfoliated graphene (a
closer analogue to two dimensional material), the in-plane carbon-carbon bonds
are unstable under X-ray irradiation, resulting in nanocrystalline structures.
As the interaction along the third dimension increases by increasing the number
of graphene layers or through the interaction with the substrate (epitaxial
graphene), the effect of X-ray irradiation decreases and eventually becomes
negligible for graphite and epitaxial graphene. Our results demonstrate the
importance of the interaction along the third dimension in stabilizing the long
range in-plane carbon-carbon bonding, and suggest the possibility of using
X-ray to pattern graphene nanostructures in exfoliated graphene.Comment: 4 pages, 3 figures, Phys. Rev. B rapid communication, in pres
Intrinsic Insulating Ground State in Transition Metal Dichalcogenide TiSe2
The transition metal dichalcogenide TiSe has received significant
research attention over the past four decades. Different studies have presented
ways to suppress the 200~K charge density wave transition, vary low temperature
resistivity by several orders of magnitude, and stabilize magnetism or
superconductivity. Here we give the results of a new synthesis technique
whereby samples were grown in a high pressure environment with up to 180~bar of
argon gas. Above 100~K, properties are nearly unchanged from previous reports,
but a hysteretic resistance region that begins around 80~K, accompanied by
insulating low temperature behavior, is distinct from anything previously
observed. An accompanying decrease in carrier concentration is seen in Hall
effect measurements, and photoemission data show a removal of an electron
pocket from the Fermi surface in an insulating sample. We conclude that high
inert gas pressure synthesis accesses an underlying nonmetallic ground state in
a material long speculated to be an excitonic insulator.Comment: 11 pages, 7 figure
A high-efficiency spin-resolved phototemission spectrometer combining time-of-flight spectroscopy with exchange-scattering polarimetry
We describe a spin-resolved electron spectrometer capable of uniquely
efficient and high energy resolution measurements. Spin analysis is obtained
through polarimetry based on low-energy exchange scattering from a
ferromagnetic thin-film target. This approach can achieve a similar analyzing
power (Sherman function) as state-of-the-art Mott scattering polarimeters, but
with as much as 100 times improved efficiency due to increased reflectivity.
Performance is further enhanced by integrating the polarimeter into a
time-of-flight (TOF) based energy analysis scheme with a precise and flexible
electrostatic lens system. The parallel acquisition of a range of electron
kinetic energies afforded by the TOF approach results in an order of magnitude
(or more) increase in efficiency compared to hemispherical analyzers. The lens
system additionally features a 90{\deg} bandpass filter, which by removing
unwanted parts of the photoelectron distribution allows the TOF technique to be
performed at low electron drift energy and high energy resolution within a wide
range of experimental parameters. The spectrometer is ideally suited for
high-resolution spin- and angle-resolved photoemission spectroscopy
(spin-ARPES), and initial results are shown. The TOF approach makes the
spectrometer especially ideal for time-resolved spin-ARPES experiments.Comment: 16 pages, 11 figure
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