Positive stabilization of a parabolic equation by controls localized on a curve

We consider the stabilization of the nonnegative solutions of linear parabolic equation by controls localized on a curve. The main results of the article give a necessary and sufficient condition for positive stabilizability in terms of the principal eigenvalue of a certain elliptic operator. In case of positive stabilizability, some feedback stabilizing controls are indicated.     

Search for narrow resonances in e+e− annihilation into hadrons at adone

A search for narrow resonances in the reaction e⁺e^? → hadrons in the mass regions 1915–2345 MeV and 2970–3090 MeV has been perforned at ADONE, the Frascati storage ring. With 90% confidence level our data exclude the production of narrow resonances with integrated cross section larger than 20% of the integrated cross section for production of the J/Ψ (3100 MeV).     

Complex and chaotic oscillations in a model for the catalytic hydrogen peroxide decomposition under open reactor conditions

Numerous periodic and aperiodic dynamic states obtained in a model for hydrogen peroxide decomposition in the presence of iodate and hydrogen ions (the Bray-Liebhafsky reaction) realized in an open reactor (CSTR), where the flow rate was the control parameter, have been investigated numerically. Between two Hopf bifurcation points, different simple and complex oscillations and different routes to chaos were observed. In the region of the mixed-mode evolution of the system, the transitions between two successive mixed-mode simple states are realized by period-doubling of the initial state leading to a chaotic window in which the next dynamic state emerges mixed with the initial one. It appears in increasing proportions in concatenated patterns until total domination. Thus, with increasing flow rate the period-doubling route to chaos was obtained, whereas with decreasing flow rate the peak-adding route to chaos was obtained. Moreover, in very narrow regions of flow rates, chaotic mixtures of mixed-mode patterns were observed. This evolution of patterns repeats until the end of the mixed-mode region at high flow rates that corresponds to chaotic mixtures of one large and many small amplitude oscillations. Starting from the reverse Hopf bifurcation point and decreasing the flow rate, simple small amplitude sinusoidal oscillations were encountered and then the period-doubling route to chaos. With a further decreasing flow rate, the mixed-mode oscillations emerge inside the chaotic window.     

One-dimensional nonlinear motions in electroelastic solids: Characteristics and shock waves

The general balance laws and jump relations of the nonlinear electroelasticity of anisotropic dielectrics presented in a previous work are systematically used to characterize and classify infinitesimal discontinuities and electroelastic shocks that can propagate in a simplified one-dimensional model. In particular, the characteristic speeds are obtained, the thermodynamical behavior of weak electroelastic shocks is established, and a classification of electroelastic shocks is given when the material admits a quadratic energy (so-called neo-Hookean case). The Hugoniot jump equation plays the fundamental role in the second point while electric switch-on and switch-off shocks can be exhibited in the classification. The work paves the way for a fully three-dimensional study in anisotropic ferroelectrics and ceramics.     

Preparation of Composite Filters Based on Porous Coordination Polymers by Using a Vacuum Filtration Method for Highly Efficient Removal of Particulate Matters

In this study, two novel crystal materials pcp1 and pcp1‐L have been synthesized successfully. The different conformations of the two crystals are mainly attributed to the introduction of the Schiff‐base ligand L ( L =(E)‐4‐methyl‐N‐((6‐methoxypyridin‐2‐yl)methylene)aniline). Subsequently, pcp1 and pcp1‐L composites have been firstly produced by a vacuum filtration method on various substrates (i.e., melamine foam, plastic mesh, carbon fiber cloth and glass cloth). The obtained robust composites show excellent performance in removing PMs owing to high ζ potential, microporous structure, large conjugation system and electron cloud‐exposed metal center (DFT calculations) of pcp1 and pcp1‐L . Particularly, pcp1‐L @glass cloth with low pressure drop exhibits high thermal stability and high long‐term reproducibility. Additionally, the high removal efficiency of pcp1‐L @glass cloth towards particulate matters could also be maintained, even achieving >99.9 % in the car exhaust gas field test.     

The 693 keV 2+′→2+ transition in154Gd

The multipolarity of the 2²⁺′→2⁺ transition in¹⁵⁴Gd has been investigated. The correlation coefficientA ₂₂=? 0.04±0.10 was determined on an electron — gamma directional correlation spectrometer, while the conversion coefficient α _K =0.046±0.002 was deduced by comparing the normalised electron and gamma intensities. From these values the quantities δ,q _K andX were calculated and compared with the theoretical predictions.     

Stabilization of a reaction-diffusion system modelling a class of spatially structured epidemic systems via feedback control

A two-component reaction-diffusion system modelling a class of spatially structured epidemic systems is considered. The system describes the spatial spread of infectious diseases mediated by environmental pollution. A relevant problem, related to the possible eradication of the epidemic, is the so called zero stabilization. In a series of papers, necessary conditions, and sufficient conditions of stabilizability have been obtained. It has been proved that it is possible to diminish exponentially the epidemic process in the whole habitat, just by reducing the concentration of the pollutant in a nonempty and sufficiently large subset of the spatial domain. The stabilizability with a feedback control of the harvesting type is related to the magnitude of the principal eigenvalue of a certain operator which is not selfadjoint. In this paper, we have proposed an approximating method for this principal eigenvalue. Further, we have faced the problem of finding the optimal position (by translation) of the support of the feedback stabilizing control in order to minimize both the infected population and the pollutant at a certain finite time.     

Null Controllability for the Dissipative Semilinear Heat Equation

We consider the exact null controllability problem for the semi- linear heat equation with dissipative nonlinearity in a bounded domain of Rⁿ . The main result of the article asserts that if the nonlinearity is even mildly superlinear, then global null controllability in an arbitrarily short time fails; instead we provide sharp estimates for the controllability time in terms of the size of the initial data.     

A comparative study on the performance of hybrid solar cells containing ZnSTe QDs in hole transporting layer and photoactive layer

In this paper, ZnSTe quantum dots-based hybrid solar cells (HSC) with two different device architectures have been investigated. The improved performance of the poly(3-hexylthiophene) (P3HT) and [6,6]phenyl C₇₁ butyric acid methyl ester (PC₇₁BM)-based bulk heterojunction (BHJ) solar cells by the incorporation of ZnSTe quantum dots (QDs) with an average size of 2.96 nm in PEDOT:PSS layer and active layer that have been demonstrated. Although the efficiency of both types of devices is almost the same, a close comparison reveals different reasons behind their improved performance. The device prepared with QDs in the HTL has shown reduced series resistance, increased shunt resistance, and improved mobility. On the other hand, QDs in the photoactive layer demonstrates increased photo-generation leading to improved efficiency.