On efficiency limit of ZnO/CH3NH3PbI3/CuI perovskite solar cells
Organometal triiodide perovskites are promising, high-performance absorbers in solar cells. Considering the perovskite as a thin film absorber, we solve transport equations and analyse the efficiency of a simple heterojunction configuration as a function of electron–hole diffusion lengths. We found that for a thin film thickness of ~1 micron the maximum efficiency of ~31% could be achieved at the diffusion length of ~100 micron.
The paper deals with an investigation of relief formation in Europa's surface. Jupiter's satellite Europa is close in size to the Moon. Its surface is covered with a layer of ice crust of thickness 10-30 km. Europa's surface is of large interest, because under the ice crust there is an ocean of liquid water creating conditions for possible life. The entire ice surface of the satellite is covered with a system of bands, valleys, and ridges. These structures are explained by the fact, that the ice surface is rather mobile and it was repeatedly broken from internal stresses and large-scale tectonic processes. The analysis performed showed that compressing, extending, shearing and bending stresses can influence some arbitrarily separated section of Europe's ice surface. The computer simulation with a finite element method (FEM) was performed to see, what types of defects could arise from such effects. The heterogeneity of the satellite's ice cover in thickness, density and temperature was taking into account during the simulation. The calculations, carried out for the cross-section of a thawed ice structure's area, have shown that, the most dangerous, from the crack formation viewpoint, is the shear stress at loading application angles of ±90°. Using models of thawed ice patches in the distributed field of temperatures, the effect of mechanical gravitation-tidal forces on the formation of surface defects on Europa was studied. It is shown that fractures and cracks can have various forms depending on the stress-strained state arising in their vicinity. The formation of such defects is caused by the chaotic set of many factors, mechanic and temperature ones predominantly. Copyright © 2013 by the International Astronautical Federation. All rights reserved.
The following topics were dealt with: human/computer interfaces; texture, depth and motor perception; neural nets; fuzzy systems; learning; product/process design; simulation; robotics; visual system cybernetics; batch processes; image compression and interpretation; AI applications; fuzzy adaptive control; decision modelling; agile manufacturing; service sector; inductive algorithms; complex systems; Petri nets; real time imaging; KBS; machine recognition; requirements engineering; inspection and shop floor control; environmental decision making; medicine; supervisory control; discrete event systems; power systems; software methods; heuristic search; vision systems; database systems; information modelling; facility design and material handling; conflict resolution; emergency management; genetic algorithms; decision making and path planning; IVHS; senses approximation; intelligent user interface; robust controllers for mechanical systems; cognitive and learning systems; command and control systems; pilot associate systems; neural net applications; real time systems; mobile robot visual processes; medical applications; utility energy systems; machine recognition; computing systems design; software engineering; military applications; data analysis; stochastic processes; guided vehicles; and stability and compensation.
We present the results of Monte Carlo simulations of the charge carrier transport in a disordered molecular system containing spatial and energetic disorders using the dipolar glass model. Model parameters of the material were chosen to fit a typical polar organic photoconductor polycarbonate doped with 30% of aromatic hydrazone, whose transport properties are well documented in literature. Simulated carrier mobility demonstrates a usual Poole-Frenkel field dependence and its slope is very close to the experimental value without using any adjustable parameter. At room temperature transients are universal with respect to the electric field and transport layer hickness. At the same time, carrier mobility does not depend on the layer thickness and transients develop a well-defined plateau where the current does not depend on time, thus demonstrating a non-dispersive transport regime. Tails of the transients decay as power law with the exponent close to −2. This particular feature indicates that transients are close to the boundary between dispersive and non-dispersive transport regimes. Shapes of the simulated transients are in very good agreement with the experimental ones. In summary, we provide a first verification of a self-consistency of the dipolar glass transport model, where major transport parameters, extracted from the experimental transport data, are then used in the transport simulation, and the resulting mobility field dependence and transients are in very good agreement with the initial experimental data. © 2013 American Institute of Physics. [http://dx.doi.org/10.1063/1.4794791]
The results concern roll pass design for rolling a round bar of a 20mm diameter from a 55mm diameter input. Concerning materials, this roll pass design must cover a wide range of steels, from low-carbon micro-alloyed steels to stainless steels. The roll pass design proposal takes into consideration lower plasticity of certain steels. The comparison was enabled by suggesting two roll pass designs. The classical oval-round roll pass design, where the maximum extension coefficient is set to 1.55 in oval and 1.22 in round grooves. The second roll pass design uses a combination of smooth part of the roll (curves) and round roll passes. Distribution of the extension coefficient in individual passes is similar to that of oval-round series. The paper also compares values of energy-force parameters calculated analytically using the method of finite elements. If we compare the distribution of temperature, stress and size of the grain, it is proved that the oval-round roll pass designs are the best as far as the balanced distribution of the above-mentioned values is concerned. The roll pas design combining smooth part of the roll with a round part does not achieve such balance. However, its advantage lies in far lower requirement for the needed length of the working part of the roll. Five passes are carried out on the smooth part of the roll, which considerably cuts down the required length of the roll body. Therefore it is this variant that will be used in the laboratory of wire rolling created within the project RMSTC.
Our approach to the problem of charge carrier transport in homogeneous polymers assumes carrier hopping on a densely packed manifold of transport (hopping) centers retaining the short-range order of the respective single crystal. The central idea, which distinguishes it from the Bassler’s disorder theory, is that the energy scatter concerns only a small fraction of hopping centers, which begin to act as traps. The majority of isoenergetic centers build up a transfer band with microscopic mobility µ0 equal to that in the respective single crystal. The origin of the energy scatter (and traps themselves) is ascribed to the elementary voids of the fluctuation free volume forming an association with the normal hopping centers.
The dipolar disorder formalism (DDF) of Borsenberger and Bдssler has been further developed based on a unified approach treating the van der Waals and the dipolar disorder energies as being roportional to mean intersite distance in a certain power. Tested against real molecularly doped polymers with the concentration of the dopant changing in a wide range, this approach gives values of the exponent lying in the interval from _1.5 to _2.5. The total disorder is represented by an algebraic combination of four material parameters relating to the dopant and the polymer matrix weighted by their relative weight concentrations. What is important, we seem to get able to explain the near constancy of the total disorder when the concentration of the polar dopant changes. Until recently, this unusual behavior of the total disorder defied any reasonable explanation.
Mathematical and computer simulation of economic processes.
The dynamics of a two-component Davydov-Scott (DS) soliton with a small mismatch of the initial location or velocity of the high-frequency (HF) component was investigated within the framework of the Zakharov-type system of two coupled equations for the HF and low-frequency (LF) fields. In this system, the HF field is described by the linear Schrödinger equation with the potential generated by the LF component varying in time and space. The LF component in this system is described by the Korteweg-de Vries equation with a term of quadratic influence of the HF field on the LF field. The frequency of the DS soliton`s component oscillation was found analytically using the balance equation. The perturbed DS soliton was shown to be stable. The analytical results were confirmed by numerical simulations.
Radiation conditions are described for various space regions, radiation-induced effects in spacecraft materials and equipment components are considered and information on theoretical, computational, and experimental methods for studying radiation effects are presented. The peculiarities of radiation effects on nanostructures and some problems related to modeling and radiation testing of such structures are considered.
This volume presents new results in the study and optimization of information transmission models in telecommunication networks using different approaches, mainly based on theiries of queueing systems and queueing networks .
The paper provides a number of proposed draft operational guidelines for technology measurement and includes a number of tentative technology definitions to be used for statistical purposes, principles for identification and classification of potentially growing technology areas, suggestions on the survey strategies and indicators. These are the key components of an internationally harmonized framework for collecting and interpreting technology data that would need to be further developed through a broader consultation process. A summary of definitions of technology already available in OECD manuals and the stocktaking results are provided in the Annex section.