Distributionally <Emphasis Type="Italic">n</Emphasis>-Scrambled Set for Weighted Shift Operators

The aim of the present paper is to investigate distributionally n-scrambled sets for weighted shift operators. We prove that the unilateral weighted shift operator admits densely invariant distributionally n-ε-scrambled linear manifolds for any ε ∈ (0, 1) and any integer n ? 2, showing that this operator can exhibit maximal distributional n-chaos on a dense invariant linear manifold. Analogous results for the bilateral weighted shift operator are also obtained.     

Electrophysical properties of solar polycrystalline silicon and its <Emphasis Type="Italic">n</Emphasis><Superscript>+</Superscript>-<Emphasis Type="Italic">p</Emphasis> structures at elevated temperatures

Results of measurements of electrophysical parameters of polycrystalline silicon (PS) and p-n-junction based on it in the temperature ranges 20–500 and 20–200°C, respectively, are presented. Correlation is found between the temperature dependences of the conductivity, mobility, and concentration of the current carriers in PS and the current generation characteristics in n ⁺-p-structures, including those caused by the impurity photovoltaic effect.     

Thermovoltaic effect of <Emphasis Type="Italic">p</Emphasis>Si-<Emphasis Type="Italic">n</Emphasis>(Si<Subscript>2</Subscript>)<Subscript>1−x</Subscript>(ZnS)<Subscript>x</Subscript> structures

The pSi-n(Si₂)_1−x (ZnS) _x (0 ≤ x ≤ 0.92) structure, on which thermovoltaic effect is observed, has been obtained by means of liquid-phase epitaxy from tin solution-melt on plates of p-type technical silicon. This effect is explained by grain boundary defects and influence of ZnS impurities in a thin layer adjacent to the p-n-junction.     

The study of factors that influence on the effectiveness of the photoconversion of <Emphasis Type="Italic">n</Emphasis>-CdS/<Emphasis Type="Italic">p</Emphasis>-CdTe heterostructures

The load characteristics of n-CdS/p-CdTe heterostructures were studied at different lighting levels with monochromatic light (λ = 632.8 nm) and white light with different spectra of radiation. It was established that the efficiency of conversation of a structure increases with increased temperature upon lighting with white light from an incandescent lamp. The results will help to optimize the structure of photocells based on CdTe polycrystalline films.     

Optimization of parameters of <Emphasis Type="Italic">n</Emphasis>-branches of solar radiation thermoconverters

The optimization of the parameters of the n branches of solar radiation thermoconverters is considered.     

Remarks on Fractional Discrete Cone Control Systems with <Emphasis Type="Italic">n</Emphasis>-Orders and Their Stability

In the paper, fractional discrete cone control systems with n-orders are considered. Some relations between invariance and (asymptotic) stability properties of the presented systems are discussed. Operators employed to the considered systems are Caputo-, Riemman-Louville-, and Grünwald-Letnikov type ones. Cone systems with control, which are particular invariant systems with control, together with their stability and asymptotic stability properties are examined.     

When a Minimal Map Is Totally Transitive on a <Emphasis Type="Italic">G</Emphasis>-Space

In this paper, we introduce the notion of G-regular periodic decomposition (GRPD) for maps on G-spaces and investigate its relation with G-transitivity. It is shown that if a pseudoequivariant, G-transitive map on a G-space has a GRPD of some length n, then its nth iterate is not G-transitive. On the other hand, if a pseudoequivariant, G-transitive map on a G-space has a non-G-transitive nth iterate, then it admits a GRPD of length p for some prime p dividing n. Using the notion of GRPD, it is obtained that a pseudoequivariant, G-minimal map is totally G-transitive on a connected G-space.     

Weak Solutions and Energy Estimates for Singular <Emphasis Type="Italic">p</Emphasis>-Laplacian-Type Equations

This paper deals with the existence results and energy estimates of solutions for singular p-Laplacian-type equations if the nonlinear term admits some suitable conditions on the behavior at origin or perturbation property. In particular, for a precise localization of the parameter, we establish the existence of a non-zero solution and deduce the existence of solutions for positive values of the parameter, with requiring (p ? 1)–sublinearity of nonlinear part at the origin and the infinity. Finally, a multiplicity result and two illustrating examples are also given. The proof is based on a local minimum theorem for differentiable functionals.     

Ten years of <Emphasis Type="Italic">Energy Efficiency</Emphasis>: a bibliometric analysis

Energy Efficiency is an international journal dedicated to research topics connected to energy with a focus on end-use efficiency issues. In 2018, the journal celebrates its 10th anniversary. In order to mark it and analyze not only how the journal has been performing over the years, but also which are the trends for academic debate and research in this journal, this article presents a bibliometric overview of the publication and citation structure of the journal during period 2008–2017. The study relies on the Web of Science Core Collection and the Scopus database to collect the bibliographic results. Additionally, the work exploits the visualization of similarities (VOS) viewer software to map graphically the bibliographic material. The research analyses the most cited papers and the most popular keywords. Moreover, the paper studies how the journal connects with other international journals and identifies the most productive authors, institutions, and countries. The results indicate that the journal has rapidly grown over the years, obtained a merited position in the scientific community, with contributions from authors all over the world (with Europe as the most productive region). Moreover, the journal has focused so far mainly on energy efficiency issues in close relationship with policies and incentives, corporate energy efficiency, consumer behavior, and demand-side management programs, with both industrial, building and transport sectors widely involved. Our discussion concludes with suggested future research avenues, in particular towards coordinated efforts from different disciplines (technical, economic, and sociopsychological ones) to address the emerging energy efficiency challenges.     

The fabrication and investigation of <Emphasis Type="Italic">n</Emphasis>/CdS-<Emphasis Type="Italic">p</Emphasis>/CdTe-<Emphasis Type="Italic">n</Emphasis>/Si structures

Attempts to obtain heterojunctions between A²B⁶ (cadmium telluride and cadmium sulfide) compounds and silicon were made. The distributions of chemical components and some photoelectric properties of the surfaces of the produced layers were investigated.     

Semi-Analytical Simulation and Optimization of AlGaAs/GaAs <Emphasis Type="Italic">p-i-n</Emphasis> Quantum Well Solar Cell

This paper deals with a AlGaAs/GaAs p-i-n quantum well solar cell. The doped region are based on AlGaAs semiconductor while the intrinsic region “I” contain multi quantum well (MQW) system AlGaAs/GaAs. A semi-analytical model in the intrinsic region and numerical drift-diffusion model in doped regions are combined to extract the total current density of the cell versus voltage. The current-voltage (J-V) characteristics are generated for the AM1.5 solar spectrum. The effect of the Aluminum molar fraction x (Al_xGa_1–xAs), the number, the width, the depth of the wells and barriers in the “i” layer and the doping densities on the electrical outputs of the solar cell are also presented. The optimized solar cell reached a conversion efficiency of 28.72% with a short circuit current density of 36.9 mA/cm² and an open circuit voltage of 0.97 V.     

Quenching of Solutions to a Class of One-dimensional <Emphasis Type="Italic">p</Emphasis>-Laplacian Dirichlet Problems

This paper concerns with the quenching phenomenon of solutions to a class of one-dimensional p-Laplacian Dirichlet problems. It is shown that there exists a critical length for the special domain in the sense that the solution exists globally in time if the length of the special domain is less than this number while the solution quenches if the length is greater than this number. The location of the quenching points for quenching solutions is also studied.     

Hot-cool box calorimetric determination of the solar heat gain coefficient and the <Emphasis Type="Italic">U</Emphasis>-value of internal shading devices

In several developing countries, energy performance rating programs are currently in progress. Complex fenestration systems (CFS) are building components that play a key role in reducing energy consumption. The development and testing of equipment is central for beginning the energy efficiency rating process of complex glazing systems in these countries. This paper validates the use of a low-cost hot-cold box calorimeter for measurement of the solar heat gain coefficient (SGHC) and overall heat transfer coefficient (U-value) of interior shading systems. This work aims to determine the energy performance of three types of often employed shading systems: solar control films, interior horizontal venetian blinds, and indoor drapery curtains. Results show that the energy performance of solar shading devices studied depends on both their morphological and optical properties. The shading systems analyzed present similar U-values, where technological features are represented by the thickness and the thermal conductivity of the material. SHGC is mainly defined by the transmittance and, to a lesser extent, the absorptance of the systems, which differ significantly according to the analyzed shading device. The three types of curtains analyzed demonstrate an SHGC dependent on the fabrics openness factor: jacquard curtains (openness factor 0.05) present a SHGC of 0.7, whereas organza curtains (openness factor 0.45) have a SHGC of 0.82. The SHGC of the venetian blinds analyzed varies on average 36% according to the slat tilt (0°–45°). The solar control films examined modify their solar gain according to their spectral selectivity.     

Experimental investigation of <Emphasis Type="Italic">U</Emphasis> value of double-glazed window with inter-pane blinds using Taguchi techniques

In this research article, Taguchi L18 orthogonal array has been employed on guarded heat plate apparatus to determine ‘unit heat loss rate’ (U value) of a double-glazed window with inter-pane venetian blinds by varying processes and glazing system’s parameters, i.e. temperature difference between hot and cold plates, low-emissivity (low-e) coating and its location, slat angle of blinds, pane spacing and hot plate temperature (selected as per composite climate in India). The analyses of the raw data and signal-to-noise (S/N) ratio of the response parameters have been performed using analysis of variance (ANOVA). The insignificance of temperature of hot plate has been reiterated. The optimum parameters predicted on the basis of analyses of S/N ratio (pooled ANOVA) are (a) temperature difference of 10 °C, (b) presence of low-e coating on inner surface of outside pane, (c) slat angle of 90° and (d) pane spacing of 32 mm. The quantification of the influence of various parameters on U value has been done through prediction of percentage contribution. The significant parameters in order of their decreasing percentage contribution are presence of low-e coating (49.2 %), slat angle (32.52 %), temperature difference between hot and cold plates (8.76 %) and pane spacing (4.33 %), respectively.     

Quenching Phenomenon of Positive Radial Solutions for <Emphasis Type="Italic">p</Emphasis>-Laplacian with Singular Boundary Flux

This paper deals with the finite time quenching phenomenon of positive radial solutions for p-Laplacian with singular boundary flux. We also discuss the corresponding quenching rate.     

An intrinsic formulation of the problem on rolling manifolds

We present an intrinsic formulation of the kinematic problem of two n-dimensional manifolds rolling one on another without twisting or slipping. We determine the configuration space of the system, which is an n(n?+?3)/2-dimensional manifold. The conditions of no-twisting and no-slipping are encoded by means of a distribution of rank n. We compare the intrinsic point of view versus the extrinsic one. We also show that the kinematic system of rolling the n-dimensional sphere over $ {\mathbb{R}^n} $ is controllable. In contrast with this, we show that in the case of SE(3) rolling over $ \mathfrak{s}\mathfrak{e}(3) $ the system is not controllable, since the configuration space of dimension 27 is foliated by submanifolds of dimension 12.     

On singularly perturbed <Emphasis Type="Italic">q</Emphasis>-difference-differential equations with irregular singularity

We study a q-analog of a singularly perturbed Cauchy problem with irregular singularity in the complex domain. We construct solutions of this problem that are holomorphic on open half-q-spirals. Using a version of a q-analog of the Malgrange–Sibuya theorem obtained by J.-P. Ramis, J. Sauloy, and C. Zhang, we show the existence of a formal power-series solution in the perturbation parameter which is the q-asymptotic expansion of these holomorphic solutions.     

On the coincidence of two manifolds associated with the Calogero model

Let R be a root system, for example, the root system associated to a semisimple Lie algebra. In [1], V. A. Golubeva and V. P. Lexin constructed two algebraic manifolds (Bethe and Dunkl manifolds) using the “universal” Dunkl operators. These manifolds were defined as subsets of the complex space ℂ ^N of dimension equal to the number of roots of the root system under consideration. The first manifold (Bethe manifold) is characterized by the following property: the Laplace operator constructed by means of Dunkl operators coincides with the “universal” Hamiltonian of the Calogero model. The second one (Dunkl manifold) is characterized by the property: the “universal” Dunkl operators commute. In this paper, the manifolds associated with the irreducible root system of Coxeter type are considered. We give their construction supposing that these manifolds are embedded in ℂ ^N/2. A theoremon the coincidence of Bethe and Dunkl manifolds is proved.      

A survey of singular curves in sub-Riemannian geometry

Sub-Riemannian geometry is the geometry of a distribution ofk-planes on an-dimensional manifold with a smoothly varying inner product on thek-planes. Singular curves are singularities of the space of paths tangent to the distribution and joining two fixed points. This survey is devoted to the singular curves, which can be length minimizing geodesics, independent of the choice of inner product.     

Possibilities of increasing the efficiency of Si and CuInSe<Subscript>2</Subscript> solar cells

The paper proposes a method of increasing the efficiency of Si and CuInSe₂ solar cells using the impact ionization and impurity photovoltaic effect in pZnTe-pSi-nSi and pZnTe-pCuInSe₂-n(CuInSe₂)_1−x (2InAs) _x structures.