69 research outputs found
Decentralization and Financial Equilibrium in a Centrally Planned Economy (CPE)
This paper deals with the fundamental problem of socialist economies: how to ensure compatibility of financial equilibrium with efficient allocation of resources in a decentralized decision-making system. In order to ensure rational allocation of resources in a decentralized system, it is indispensable to apply marginal pricing of labour, materials and foreign currencies. In order to ensure financial equilibrium on the consumer market the financial system operates with average cost pricing rules, thus violating efficiency rules. Trying to solve this dilemma the constructors of economic reforms of the system give priority to financial equilibrium conditions by using average cost prices and exchange rates and correct them by subsidies differentiated for branches. This leads to bargaining processes and to the neglect of efficiency rules. The author proposes instead the use of a uniform subsidy of the central budget and presents variants of this systemic solution: in the form of a uniform subsidy to wage earners or in the form of a uniform subsidy to enterprises. The formalized analysis is included in the appendix
Energy: Prospects and Policy Issues in Intra-CMEA Relations
This paper presents an exploratory review of publications dealing with past trends and projections concerned with energy in intra-CMEA relations.
The research should be useful in the identification of directions for IIASA's research on "Mineral Markets and Trade". I hope that the collection of materials presented here may also be looked upon as the first stage of a study of energy-related issues in intra-CMEA relations.
Due to the strict time-limit imposed on this work, it was not possible to review all of the non-CMEA publications listed in the bibliography. However, the main weakness of this research lies in the lack of information from CMEA countries. This could possibly be overcome by collaborating directly with institutes in CMEA countries. Without this information, this review should be regarded as an incomplete working draft
High accuracy Raman measurements using the Stokes and anti-Stokes lines
We show that by measuring the separation between the Stokes and anti-Stokes peaks excited by two different laser lines we obtain a very precise determination of absolute phonon energies. The method is useful for measuring small changes of these energies with strain, temperature, laser power, etc. It doubles the changes and avoids the necessity of using the reference lines in the Raman spectra. The method can be applied for the determination of phonon deformation potentials, for the characterization of strained heteroepitaxial layers, and for micro-Raman analysis of strain in silicon integrated circuits. We give examples of phonon shifts in Si, Ge, GaAs, InAs, and GaP as a function of applied biaxial strain, laser power, and [email protected] ; [email protected]
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Evidence for “dark charge” from photoluminescence measurements in wide InGaN quantum wells
Wide (15-25 nm) InGaN/GaN quantum wells in LED structures were studied by time-resolved photoluminescence (PL) spectroscopy and compared with narrow (2.6 nm) wells in similar LED structures. Using below-barrier pulsed excitation in the microsecond range, we measured increase and decay of PL pulses. These pulses in wide wells at low-intensity excitation show very slow increase and fast decay. Moreover, the shape of the pulses changes when we vary the separation between them. None of these effects occurs for samples with narrow wells. The unusual properties of wide wells are attributed to the presence of “dark charge” i.e., electrons and holes in the ground states. Their wave functions are spatially separated and due to negligible overlap they do not contribute to emission. However, they screen the built-in field in the well very effectively so that excited states appear with significant overlap and give rise to PL. A simple model of recombination kinetics including “dark charge” explains the observations qualitatively
General boundary conditions for the envelope function in multiband k.p model
We have derived general boundary conditions (BC) for the multiband envelope
functions (which do not contain spurious solutions) in semiconductor
heterostructures with abrupt heterointerfaces. These BC require the
conservation of the probability flux density normal to the interface and
guarantee that the multiband Hamiltonian be self--adjoint. The BC are energy
independent and are characteristic properties of the interface. Calculations
have been performed of the effect of the general BC on the electron energy
levels in a potential well with infinite potential barriers using a coupled two
band model. The connection with other approaches to determining BC for the
envelope function and to the spurious solution problem in the multiband k.p
model are discussed.Comment: 15 pages, 2 figures; to be published in Phys. Rev. B 65, March 15
issue 200
Interface electronic states and boundary conditions for envelope functions
The envelope-function method with generalized boundary conditions is applied
to the description of localized and resonant interface states. A complete set
of phenomenological conditions which restrict the form of connection rules for
envelope functions is derived using the Hermiticity and symmetry requirements.
Empirical coefficients in the connection rules play role of material parameters
which characterize an internal structure of every particular heterointerface.
As an illustration we present the derivation of the most general connection
rules for the one-band effective mass and 4-band Kane models. The conditions
for the existence of Tamm-like localized interface states are established. It
is shown that a nontrivial form of the connection rules can also result in the
formation of resonant states. The most transparent manifestation of such states
is the resonant tunneling through a single-barrier heterostructure.Comment: RevTeX4, 11 pages, 5 eps figures, submitted to Phys.Rev.
Coherent state of a nonlinear oscillator and its revival dynamics
The coherent state of a nonlinear oscillator having a nonlinear spectrum is
constructed using Gazeau Klauder formalism. The weighting distribution and the
Mandel parameter are studied. Details of the revival structure arising from
different time scales underlying the quadratic energy spectrum are investigated
by the phase analysis of the autocorrelation function
New Method for Studying Biaxial Deformation Effects on Optical Spectra of Quantum Wells
The effects of large deformation were studied by preparing thin (20-30 μm) membranes with quantum-well layers on top. A small gas pressure of a few bar deforms the membrane substantially and changes the optical spectra of the quantum wells. We present the results of the photoluminescence and absorption from GaAs/AlGaAs and from InGaAs/GaAs quantum wells subjected to tensile and to compressive biaxial strain. The light-hole lines shift more than two times faster than the heavy-hole lines so that they cross under tensile strain
Wide Range Wavelength Tuning of InGaAsP/InP Laser Diodes
We present results of theoretical studies of external tuning for laser diodes based on InGaAsP/InP heterostructures at temperatures from 300 K down to 80 K and at hydrostatic pressures up to 2.27 GPa. The tuning range achieved by pressure and grating was 390 nm (from 1220 nm to 1610 nm). At lower temperatures the tuning range achieved with grating was significantly reduced. Our results indicate that pressure tuning is much more effective than temperature tuning when combined with tuning by external grating
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