428 research outputs found
Capital market imperfections, uncertainty and corporate investment in the Czech Republic
The well-known Klein-Monti model of bank behavior considers a monopolistic bank. We demonstrate that this modelās results on the comparative static effects of a change in the exogenous interbank market interest rate do not necessarily hold in oligopolistic Cournot or Stackelberg generalizations. Introducing asymmetries in the cost functions of the banks, or in their way of conduct, may imply counterintuitive effects on the individual banksā volumes of loans and deposits. Keywords: Bank behavior, Cournot oligopoly, Stackelberg oligopoly
Characterisation of an Electrostatic Vibration Harvester
Harvesting energy from ambient vibration is proposed as an alternative to
storage based power supplies for autonomous systems. The system presented
converts the mechanical energy of a vibration into electrical energy by means
of a variable capacitor, which is polarized by an electret. A lumped element
model is used to study the generator and design a prototype. The device has
been micromachined in silicon, based on a two-wafer process. The prototype was
successfully tested, both using an external polarization source and an
electret.Comment: Submitted on behalf of EDA Publishing Association
(http://irevues.inist.fr/EDA-Publishing
A new power MEMS component with variable capacitance
Autonomous devices such as wireless sensors and sensor networks need a long battery lifetime in a small volume. Incorporating micro-power generators based on ambient energy increases the lifetime of these systems while reducing the volume. This paper describes a new approach to the conversion of mechanical energy, available in vibrations, to electrical energy. The conversion principle is based on charge transportation between two parallel capacitors. An electret is used to polarize the device. A large-signal model was developed, allowing simulations of the behavior of the generator. A small-signal model was then derived in order to quantify the output power as a function of the design parameters. These models show the possibility of generating up to 40 muW with a device of 10 mm 2. A layout was made based on a standard SOI-technology, available in an MPW. With this design a power of 1 muW at 1020 Hz is expected
A Binary Orbit for the Massive, Evolved Star HDE 326823, a WR+O System Progenitor
The hot star HDE 326823 is a candidate transition-phase object that is
evolving into a nitrogen-enriched Wolf-Rayet star. It is also a known
low-amplitude, photometric variable with a 6.123 d period. We present new, high
and moderate resolution spectroscopy of HDE 326823, and we show that the
absorption lines show coherent Doppler shifts with this period while the
emission lines display little or no velocity variation. We interpret the
absorption line shifts as the orbital motion of the apparently brighter star in
a close, interacting binary. We argue that this star is losing mass to a mass
gainer star hidden in a thick accretion torus and to a circumbinary disk that
is the source of the emission lines. HDE 326823 probably belongs to a class of
objects that produce short-period WR+O binaries.Comment: 32 pages, 10 figures, accepted to the Astronomical Journa
The option to wait to invest and equilibrium credit rationing
Stiglitz and Weiss (1981) show that firms considering risky projects have higher reservation interest rates and hence it is optimal for a bank to reduce loan supply. In this note we show that when the risk involved in an investment will be resolved in the future, investors with riskier projects have a greater return from waiting. More risky projects have lower reservation interest rates and hence there is no motive for banks to ration credit demand
Motion-Based Generators for Industrial Applications
Scaling down of electronic systems has generated a large interest in the
research on miniature energy sources. In this paper a closer look is given to
the use of vibration based scavengers in industrial environments, where waste
energy is abundantly available as engine related vibrations or large amplitude
motions. The modeling of mechanical generators resulted in the design and
realization of two prototypes, based on electromagnetic and electrostatic
conversion of energy. Although the prototypes are not yet optimized against
size and efficiency, a power of 0.3 mW has been generated in a 5 Hz motion with
a 0.5 meter amplitude.Comment: Submitted on behalf of TIMA Editions
(http://irevues.inist.fr/tima-editions
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