On the Geometry of Rolling and Interpolation Curves on <Emphasis Type="Italic">S</Emphasis><Superscript><Emphasis Type="Italic">n</Emphasis></Superscript>, SO<Subscript><Emphasis Type="Italic">n</Emphasis></Subscript>, and Grassmann Manifolds

We present a procedure to generate smooth interpolating curves on submanifolds, which are given in closed form in terms of the coordinates of the embedding space. In contrast to other existing methods, this approach makes the corresponding algorithm easy to implement. The idea is to project the prescribed data on the manifold onto the affine tangent space at a particular point, solve the interpolation problem on this affine subspace, and then project the resulting curve back on the manifold. One of the novelties of this approach is the use of rolling mappings. The manifold is required to roll on the affine subspace like a rigid body, so that the motion is described by the action of the Euclidean group on the embedding space. The interpolation problem requires a combination of a pullback/push forward with rolling and unrolling. The rolling procedure by itself highlights interesting properties and gives rise to a new, but simple, concept of geometric polynomial curves on manifolds. This paper is an extension of our previous work, where mainly the 2-sphere case was studied in detail. The present paper includes results for the n-sphere, orthogonal group SO _n , and real Grassmann manifolds. In particular, we present the kinematic equations for rolling these manifolds along curves without slip or twist, and derive from them formulas for the parallel transport of vectors along curves on the manifold.      

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.     

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.     

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.     

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.     

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.     

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.     

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.     

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.     

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 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.     

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.     

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.     

Inhibition of NO emission by adding antioxidant mixture in <Emphasis Type="Italic">Jatropha</Emphasis> biodiesel on the performance and emission characteristics of a C.I. engine

In this paper, the effect of adding an antioxidant mixture in Jatropha biodiesel as fuel, in a single cylinder, direct injection compression ignition engine was experimentally investigated and the level of pollutants in the exhaust and performance characteristics of the engine were analyzed. Nine test fuels were prepared with three antioxidants, namely, Succinimide (C₄H₅NO₂), N,N-dimethyl-p-phenylenediamine-dihydrochloride (C₈H₁₄Cl₂N₂), and N-phenyl-p-phenylenediamine (C₆H₅NHC₆H₄NH₂) added to neat biodiesel at 500 parts per million (ppm), 1000 ppm and 2000 ppm and the observed experimental results were compared with those of neat biodiesel and neat diesel as base fuels. The comparison showed that NO emission was reduced drastically for the test fuels with the antioxidant addition of 2000 ppm. The maximum reduction of 10% of NO emission was observed for the antioxidant mixture in neat biodiesel, with a slight increase in unburned HC, CO and smoke opacity. In addition, the obtained experimental results reveal that the addition of two antioxidants as mixture in neat biodiesel caused improved NO emission reduction for all test fuels.     

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.     

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.     

Existence of Solutions and Approximate Controllability of Fractional Nonlocal Neutral Impulsive Stochastic Differential Equations of Order 1 &lt; <Emphasis Type="Italic">q</Emphasis> &lt; 2 with Infinite Delay and Poisson Jumps

In this paper, we study the existence of mild solutions and the approximate controllability of nonlinear fractional nonlocal neutral impulsive stochastic differential equations of order 1 < q < 2 with infinite delay and Poisson jumps in which the initial value belong to the abstract phase space C _h . The existence of mild solutions is derived with the help of Sadovskii’s fixed point theorem. The approximate controllability of the nonlinear fractional nonlocal neutral impulsive stochastic differential systems of order 1 < q < 2 with infinite delay and Poisson jumps is discussed under the assumption that the corresponding linear system is approximately controllable. Moreover, the approximate controllability of the above control system is established by using Lebesgue dominated convergence theorem. An example is provided to illustrate the theory.     

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.     

Current sensitivity and efficiency of a CdO-<Emphasis Type=Italic>p</Emphasis>CdTe-Mo structure at low light levels

It is shown that the CdO-pCdTe-Mo structure established on the basis of large-block p-type films has a spectral range of photosensitivity of Δλ = 480–830 nm, which fully covers the visible area of solar radiation. It was found that the CdO-pCdTe-Mo structure has a high integral sensitivity of S _int = 430–520 mA/lm and a high efficiency of illumination by light of E = 10–100 lx. The anomalous behavior of S _int and the efficiency of this structure are explained by an increase in the photocurrent due to redistribution of the potential between the barrier and the series resistance of the structure as a result of illumination.     

Photosensitivity of polycrystalline silicon fabricated by fivefold remelting of metallurgical silicon in a solar furnace and <Emphasis Type=Italic>n-p</Emphasis> structures made of this material

The spectral photosensitivity of polycrystalline silicon fabricated by fivefold remelting of metallurgical silicon in an outdoor solar furnace is investigated. It is found that a structure made of this material with two simple ohmic contacts possesses a voltaic photosensitivity in the IR range of the spectrum (0.3–1.0 eV). More-over, a structure made of this material by the diffusion of boron with an n-p transition also has an IR spectral sensitivity over a large range (0.3–1.8 eV).