FEM Analysis of Piezoelectric Resonator Polarization Process

The polarization of the piezoelectric resonator depends on the direction of the applied electric field. The direction of the applied electric field is determined by the shape of the resonator and the position of the electrodes. In case of resonators with electrodes incompletely covering their bases, an inhomogeneous electric field is generated, which results in an inhomogeneous polarization of the resonator. The resonator will be polarized in some places either in a direction other than the desired one or not polarized at all. The aim of this work is to analyze the polarization process on resonators with electrodes incompletely covering their bases. The physical description is given by the linear piezoelectric equations, the Gaussian equation for the description of the electric field and by Newton’s law of force. On this basis, a FEM model is developed and used to analyze the polarization process. The results of the calculation of the electric field vector distribution are presented. Finally, the areas are identified in which polarization in the desired direction is achieved in the resonator as well as the ones where no polarization occurs.

Modeling Multidimensional Public Opinion Polarization Process under the Context of Derived Topics

With the development of Internet technology, the speed of information dissemination and accelerated updates result in frequent discussion of topics and expressions of public opinion. In general, multi-dimensional discussion topics related to the same event are often generated in the network, and the phenomenon of multi-dimensional public opinion polarization is formed under the mutual influence of groups. This paper targets the phenomenon of multi-dimensional public opinion polarization under topic-derived situations as the research object. Firstly, this paper identifies the factors influencing multi-dimensional public opinion polarization, including the mutual influence of different topic dimensions and the interaction of viewpoints within the same topic. Secondly, the topic correlation coefficient is introduced to describe the correlation among topics in different dimensions, and the individual topic support degree is used to measure the influence of topics in different dimensions and that of information from external intervention on individual attitudes. Thirdly, a multi-dimensional public opinion polarization model is constructed by further integrating multi-dimensional attitude interaction rules. Finally, the influence of individual participation, topic status, topic correlation coefficient and external intervention information on the multi-dimensional public opinion polarization process is analyzed through simulation experiments. The simulation results show that:(1) when there is a negative correlation between multi-dimensional topics, as the number of participants on different dimensional topics becomes more consistent, the conflict between multi-dimensional topics will weaken the polarization effect of overall public opinion. However, the effect of public opinion polarization will be enhanced alongwith the enhancement in the confidence of individual opinions. (2) The intervention of external intervention information in different dimensions at different times will further form a multi-dimensional and multi-stage public opinion polarization, and when the multi-dimensional topics are negatively correlated, the intervention of external intervention information will have a stronger impact on the multi-dimensional and multi-stage public opinion polarization process. Finally, the rationality and validity of the proposed model are verified by a real case.

Tautomerism of para-Aminobenzylidene-para-methoxyaniline

ABSTRACT: In the early seventies received wide attention when Patai [1] published his book tagged the chemistry of the azomethane group and the aforementioned group is very important in the fields of chemistry, life sciences, chemical and pharmaceutical industries and medicine. The chemistry of imines includes two main groups is Schiff bases and oximes. as well as presence of double bonds in the imines facilitated the possibility of their presence in the form of two Geometrical Isomers. Curtin and Husser [2] are among the first to discover the presence of imines in two forms, syn and anti, and the inability to separate these two forms in the imines is attributed to the freedom to rotate around the double bonds between The carbon and nitrogen atoms, which reduce the occurrence of the polarization process in C=N and facilitate the rotation process [3]. Keywords: tautomerism, organic chemistry, azomethane group

Variational inequalities for ferroelectric constitutive modeling

This paper is concerned with modeling the polarization process in ferroelectric media. We develop a thermodynamically consistent model, based on phenomenological descriptions of free energy as well as switching and saturation conditions in form of inequalities. Thermodynamically consistent models naturally lead to variational formulations. We propose to use the concept of variational inequalities. We aim at combining the different phenomenological conditions into one variational inequality. In our formulation we use one Lagrange multiplier for each condition (the onset of domain switching and saturation), each satisfying Karush-Kuhn-Tucker conditions. An update for reversible and remanent quantities is then computed within one, in general nonlinear, iteration.

High-order mixed finite elements for an energy-based model of the polarization process in ferroelectric materials

An energy-based model of the ferroelectric polarization process is presented in the current contribution. In an energy-based setting, dielectric displacement and strain (or displacement) are the primary independent unknowns. As an internal variable, the remanent polarization vector is chosen. The model is then governed by two constitutive functions: the free energy function and the dissipation function. Choices for both functions are given. As the dissipation function for rate-independent response is non-differentiable, it is proposed to regularize the problem. Then, a variational equation can be posed, which is subsequently discretized using conforming finite elements for each quantity. We point out which kind of continuity is needed for each field (displacement, dielectric displacement and remanent polarization) is necessary to obtain a conforming method, and provide corresponding finite elements. The elements are chosen such that Gauss’ law of zero charges is satisfied exactly. The discretized variational equations are solved for all unknowns at once in a single Newton iteration. We present numerical examples gained in the open source software package Netgen/NGSolve.

NITROGEN MANAGEMENT – AN IMPORTANT DETERMINANT OF SUSTAINABLE AGRICULTURE

The aim of the paper is to identify changes in nitrogen management in individual agriculture and result assessment in the context of sustainable development. The paper showed the essential elements of nitrogen balancing on agricultural area. Research was conducted at a national as well as voivodship level, making it possible to determine the scale of diversity of regional nitrogen management in individual agriculture and verify the regional divergence process in this scope. Analysis was based on data collected during the Farm Structure Survey in 2007 and 2016 prepared by the Statistical Office in Olsztyn, for individual farms with at least 1 ha of UAA in GAEC. The period of research captured the trend of changes in nitrogen management on farms over a 10 year-period. Nitrogen gross balance was calculated on the basis of OECD and EUROSTAT methodology. The results indicated the need to improve nitrogen management to optimize it in relation to crop nutritional needs and local soil conditions. Not only environmental considerations but, above all, economic ones, are an important prerequisite for increasing farmer interest in such activities. Regional diversification of nitrogen economy is progressing, indicating an ongoing divergence (polarization) process. This process is the result of a number of different factors, including organizational and environmental ones.

Models of inhomogeneous polarization of ferroelectrics and their practical application

A three-dimensional mathematical model is proposed that describes the ferroelectric response of polycrystalline ferroelectrics to an electric field in the absence of mechanical stresses. It is based on the separation of the switching process into two related parts: the rotation of the spontaneous polarization vectors and the destruction of the domain wall fixing mechanisms. For each of the parts, the energy costs are calculated, which are the components of the energy balance in the real polarization process. The constitutive relations for the induced and residual components of the polarization vector of the representative volume are obtained. A number of numerical experiments were performed, which showed good agreement with the experimental data.

Поляризационные процессы в тонких слоях аморфного MoS-=SUB=-2-=/SUB=-, полученных методом высокочастотного магнетронного распыления

The polarization processes in thin layers of amorphous molybdenum disulfide MoS_2 are studied by dielectric spectroscopy techniques. The process of dipole-relaxation polarization is observed. The microscopic parameters of the system are calculated, and the relaxation time of the dipole-polarization process, as well as the activation energies E _ a and E _σ of the relaxation process and conductivity, respectively, are determined. The fact that the two activation energies are close to each other suggests that the processes of relaxation and charge transport are driven by the same mechanism.