Differentiability of the Value Function of Nonclassical Optimal Growth Models

We consider an optimal growth (multi-sector) model with nonconvex technology. Using the Clarke results on generalized gradients, we prove that the value function has left and right derivatives with respect to the initial capital stock, without requiring supermodularity assumptions.     

Behaviour of Self-Standing CVD Diamond Film with Different Dominant Crystalline Surfaces in Thermal-Iron Plate Polishing

Self-standing CVD diamond films with different dominant crystalline surfaces are polished by the thermal-iron plate polishing method. The influence of the dominant crystalline surfaces on polishing etfficiency is investigated by measuring the removal rate and final roughness. The smallest rms roughness of 0.14 μm is measured with smallest removal rate in the films with the initial （220） dominant crystalline surface. Activation energy for the polishing is analysed by the Arrhenius relation. It is found that the values are 170kJ/mol, 222kJ/mol and 214kJ/mol for the film with three different dominant crystalline surfaces. Based on these values, the polishing cause is regarded as the graphitization-controlling process. In the experiment, we find that transformation of the dominant crystalline surfaces from （111） to （220） always appears in the polishing process when we polish the （111） dominant surface.     

One-pot four-component domino strategy for the synthesis of novel spirooxindole–pyrrolidine/pyrrolizidine-linked 1,2,3-triazole conjugates via stereo- and regioselective [3+2] cycloaddition reactions: In vitro antibacterial and antifungal studies

In this study, a series of highly diversified novel functionalized spirooxindolopyrrolidine and spirooxindolopyrrolizidine-linked 1,2,3-triazole conjugates have been synthesized by a one-pot, four-component condensation of (E)-2-(1-propargyl-2-oxoindoline-3-ylidene)acetophenones as bifunctional dipolarophiles, acenaphthenequinone, α-amino acids with substituted aryl azides using coinage metal catalysts. It was found that CuSO₄/Na ascorbate as a catalyst was more performant than Ag₂CO₃ or CuI. The single-crystal X-ray analysis of one of the cycloadducts proves the structure and the regiochemistry of this reaction. The compounds have been screened for their in vitro antibacterial and antifungal activities using the agar dilution method and display good activities.     

Study of dielectric properties of composite insulators for use in medium voltage overhead lines

The dielectric properties of composite insulator materials based on silicone are studied as a function of ageing factors (temperature, UV). Our study includes composite insulators used in the Tunisian Electricity and Gas Company STEG networks (medium voltage overhead lines). Macroscopic characterization using conventional normalized test was performed at the Center of Measurement Tests of El Omrane (Tunis). In the other hand, samples taken from treated insulator are investigated by dielectric spectroscopy technique. The measurement was carried out according to the same ageing factors. So the correlation between the results of standardized tests and those obtained by laboratory characterization is possible. The results of our measurements show the existence of significant dielectric losses in the case of samples that have been aged under temperature and UV radiation. We attribute these losses to the rate of added filler during material elaboration. The dielectric losses increase respectively with time and ageing factors. This increase is remarkable at the vicinity of industrial frequencies.     

Three-dimensional radiative transfer modeling using the control volume finite element method

In the present study, a three-dimensional algorithm for the treatment of radiative heat transfer in emitting, absorbing and scattering media is developed. The approach is based on the utilization of control volume finite element method (CVFEM) which, to the knowledge of the authors, is applied at the first time to 3D radiative heat transfer in participating media. The accuracy of the present algorithm is tested by comparing its predictions to other published works. Comparisons show that CVFEM produces good results. Moreover, this approach permits compatibility with other numerical methods used for computational fluids mechanics problems.     

Application of the lattice Boltzmann method to transient conduction and radiation heat transfer in cylindrical media

In this paper, the lattice Boltzmann method (LBM) is applied to solve the energy equation of a transient conduction-radiation heat transfer problem in a two-dimensional cylindrical enclosure filled with an emitting, absorbing and scattering media. The control volume finite element method (CVFEM) is used to obtain the radiative information. To demonstrate the workability of the LBM in conjunction with the CVFEM to conduction-radiation problems in cylindrical media, the energy equation of the same problem is also solved using the finite difference method (FDM). The effects of different parameters, such as the grid size, the scattering albedo, the extinction coefficient and the conduction-radiation parameter on temperature distribution within the medium are studied. Results of the present work are compared with those available in the literature. LBM-CVFEM results are also compared with those given by the FDM-CVFEM. In all cases, good agreement has been obtained.     

Control volume finite element method for radiation

In this paper a new methodology is presented by the authors for the numerical treatment of radiative heat transfer in emitting, absorbing and scattering media. This methodology is based on the utilisation of Control Volume Finite Element Method (CVFEM) and the use, for the first time, of matrix formulation of the discretized Radiative Transfer Equation (RTE). The advantages of the proposed methodology is to avoid problems that confronted when previous techniques are used to predict radiative heat transfer, essentially, in complex geometries and when there is scattering and/or non-black boundaries surfaces. Besides, the new formulation of the discretized RTE presented in this paper makes it possible to solve the algebraic system by direct or iterative numerical methods. The theoretical background of CVFEM and matrix formulation is presented in the text. The proposed technique is applied to different test problems, and the results compared favourably against other published works. Moreover this paper discusses in detail the effects of some radiative parameters, such as optical thickness and walls emissivities on the spatial evolution of the radiant heat flux. The numerical simulation of radiative heat transfer for different cases using the algorithm proposed in this work has shown that the developed computer procedure needs an accurate CPU time and is exempt of any numerical oscillations.     

Time dependence of secondary electron yield and of surface potential during charging of amorphous silica target

We study herein the charge evolution of a silica amorphous target submitted to an electronic bombardment. During the bombardment, the injected electronic charge and the primary energy as well as the surface bombardment of the target are controlled. The dynamics of the injected charge are described by combining measurements of the secondary electron and X-ray emission using a scanning electron microscope. Thus, we are able to access the evolution of the surface potential and secondary electron yield. Monte-Carlo calculations are used to simulate situations similar to our experiences and to study the effect of certain parameters (density of traps, energy of activation) inaccessible to the measures with our devices.     

Straightforward and Highly Diastereoselective Synthesis of a New Set of Functionalized Dispiropyrrolidines Involving Multicomponent 1,3‐Dipolar Cycloaddition with Azomethine Ylides

The diastereoselective synthesis of novel series of dispiropyrrolidines has been achieved by a one‐pot three‐component [3 + 2] cycloaddition reaction of (E)‐2‐arylideneindanones, glycine ethyl ester, and the cyclic diketones 1H‐indole‐2,3‐dione (isatin) or acenaphthenequinone. Moreover, we disclose an unprecedented epimerization of spiroadducts leading to a new family of dispiropyrrolidines with an unusual relative stereochemistry.     

Nonaxisymmetric radiative transfer in inhomogeneous cylindrical media with anisotropic scattering

In this paper, the control volume finite element method (CVFEM) is applied for the first time to solve nonaxisymmetric radiative transfer in inhomogeneous, emitting, absorbing and anisotropic scattering cylindrical media. Mathematical formulations as well as numerical implementation are given and the final discretized equations are based on similar meshes used for convective and conductive heat transfer in computational fluid dynamic analysis. In order to test the efficiency of the developed method, four nonaxisymmetric problems have been examined. Also, the grid dependence and the false scattering of the CVFEM are investigated and compared with the finite volume method and the discrete ordinates interpolation method.