Probe studies of silicon p-n junctions

The results of single-probe studies of thick and thin silicon p-n junctions are described. The electric fields in a diode with a p⁺-n junction and in a stabilitron with a p-n junction in the forward and reverse directions are studied. Measurements are made at various currents and temperatures. The p-n junctions are analyzed on the basis of the probe measurements.     

Generalized twist for the torsion of micropolar cylinders

Summary A problem of Truesdell concerning the theory of torsion is studied in the framework of micropolar elasticity.

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Sommario Un problema di Truesdell relativo alla teoria di torsione viene studiato nell'ambito dell'elasticità micropolare.

     

A generalized theory of linear micropolar thermoelasticity

Summary The linear theory of thermoelasticity established by Green and Lindsay with the help of an entropy production inequality proposed by Green and Laws is generalized to the case of a homogeneous micropolar continuum. The basic equations are derived using invariance conditions under superposed rigid body motions.

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Sommario La teoria lineare della termoelasticità stabilita da Green e Lindsay sulla base della disuguaglianza della produzione dell'entropia proposta da Green e Laws è generalizzata al caso di un continuo micropolare omogeneo. Le equazioni fondamentali vengono derivate usando condizioni di invarianza rispetto a moti rigidi sovrapposti.

     

The conjugate heat transfer of the partially heated microchannels

In this paper, the conjugate heat transfer of the water flow inside the microtube (D _i/D _o = 0.1/03 and 0.1/0.5 mm) was investigated. The laminar regime was considered with Re up to 200, input heat transfer rate of Q ₀ = 0.1 W and variable thermophysical properties of the water. Two different cases of the partial joule heating were considered for the tube wall. In the first case the tube wall was heated near the inlet of the tube (upstream heating) while, in the second case, the outlet portion of the wall was heated (downstream heating). In order to investigate the influence of the tube material on the heat transfer behavior and limits of the axial conduction inside the wall, three different tube wall materials were considered, stainless steel (k = 15.9 W/m K), silicon (k = 189 W/m K) and copper (k = 398 W/m K).     

Comparison between the Test and Simulation Results for PLA Structures 3D Printed,Bending Stressed

The additive manufacturing process is one of the technical domains that has had a sustained development in recent decades. The designers’ attention to equipment and materials for 3D printing has been focused on this type of process. The paper presents a comparison between the results of the bending tests and those of the simulation of the same type of stress applied on 3D-printed PLA and PLA–glass structures. The comparison of the results shows that they are close, and the simulation process can be applied with confidence for the streamline of filament consumption, with direct consequences on the volume and weight of additive manufactured structures. The paper determines whether the theories and concepts valid in the strength of materials can be applied to the additive manufacturing pieces. Thus, the study shows that the geometry of the cross-section, by its shape (circular or elliptical) and type (solid or ring shaped), influences the strength properties of 3D-printed structures. The use of simulation will allow a significant shortening of the design time of the new structures. Moreover, the simulation process was applied with good results on 3D-printed structures in which two types of filaments were used for a single piece (structure).     

Analysis of orthogonality and of orbits in affine iterated function systems

We introduce a duality for affine iterated function systems (AIFS) which is naturally motivated by group duality in the context of traditional harmonic analysis. Our affine systems yield fractals defined by iteration of contractive affine mappings. We build a duality for such systems by scaling in two directions: fractals in the small by contractive iterations, and fractals in the large by recursion involving iteration of an expansive matrix. By a fractal in the small we mean a compact attractor X supporting Hutchinson’s canonical measure μ, and we ask when μ is a spectral measure, i.e., when the Hilbert space has an orthonormal basis (ONB) of exponentials . We further introduce a Fourier duality using a matched pair of such affine systems. Using next certain extreme cycles, and positive powers of the expansive matrix we build fractals in the large which are modeled on lacunary Fourier series and which serve as spectra for X. Our two main results offer simple geometric conditions allowing us to decide when the fractal in the large is a spectrum for X. Our results in turn are illustrated with concrete Sierpinski like fractals in dimensions 2 and 3. Research supported in part by the National Science Foundation DMS 0457491.     

Stability for the Dirichlet Problem under Continuous Steiner Symmetrization

In this paper we prove the existence of a deformation transforming an arbitrary open set into the ball, which has the following properties: it keeps constant the measure, the kth eigenvalue of Laplace–Dirichlet operator is continuous from the left and the first eigenvalue is decreasing. The deformation is given by a sequence of continuous Steiner symmetrizations, and the behavior of the eigenvalues is related to the stability of the Dirichlet problem.     

Aspects of thermal transfer in heat treatment of alloy steels using concentrated solar energy

Journal of Thermal Analysis and Calorimetry - Heat treatments were applied to alloy steels (X210Cr12 and HS6-5-2-5) using concentrated solar energy as the thermal energy source. The characteristic...     

Constructive Néron Desingularization of algebras with big smooth locus

An algorithmic proof of the General Néron Desingularization theorem and its uniform version is given for morphisms with big smooth locus. This generalizes the results for the one-dimensional case (cf. [10 Pfister, G., Popescu, D. (2017). Constructive General Neron Desingularization for one dimensional local rings. J. Symbolic Comput. 80:570–580.[Crossref], [Web of Science ®] , [Google Scholar]], [7 Khalid, A., Pfister, G., Popescu, D. (2018). A uniform General Neron Desingularization in dimension one. J. Algebra Appli. 16. arXiv:AC/1612.03416. [Google Scholar]]).     

Ordered mesoporous silicon carbide (OM-SiC) via polymer precursor nanocasting

Ordered mesoporous SiC with high specific surface area (650-800 m(2) g(-1)) and well ordered pore structure was obtained via nanocasting of polycarbosilanes into SBA-15 and subsequent conversion of the polymer at 1300 degrees C.