Positivismo, educação e hegemonia

O exercício de reflexão presente neste estudo procura compreender e analisar a presença da filosofia positiva de Auguste Comte, entre finais do século XIX e início do século XX - momento de transformações econômicas, sociais e fundamentalmente política - entre os círculos intelectuais no Brasil, com particular interesse em sua introdução no pensamento educacional brasileiro. Com efeito, procuramos incidir nossa pesquisa pela difusão do positivismo na educação a partir de dois intelectuais específicos: Benjamin Constant e José Veríssimo. Por ambos, traçarem um debate que buscava, cada qual a seu modo, a partir do ideário positivista, empreender mudanças que trariam ao Brasil o progresso e a ordem civilizatória nos mesmos marcos que se dispunham na Europa ocidental e nos Estados Unidos. Intencionamos, deste modo, expressar que a formação de certas camadas intelectuais, centradas nos preceitos positivistas, manifestava a busca por hegemonia, no sentido explicitado por Antonio Gramsci (2000, 2004), de uma elite republicana e abolicionista, composta por frações militares, funcionários públicos, bem como, de uma pequena burguesia ainda em formação constituída por profissionais liberais, tais como, escritores, médicos, jornalistas, entre outros. Tal grupo, longe de expressarem um todo coeso, procurava disputar suas concepções de mundo junto ao Estado brasileiro.

Dual-Band Millimeter Wave Microstrip Patch Antenna with StubResonators for 28/38 GHz Applications

A dual band monopole antenna with triangle stubs operated at 28/38 GHz applications is introduced. The introduced dual band antenna is used for next 5G applications. The introduced antenna is designed on a Rogers RT 4003 with height h = 0.203 mm, dielectric constant ɛr = 3.55 and over dimensions of 12×12×0.237 mm3. The simulated results show that the presented design has two bands, the first one is from 25.9 to 30.4 GHz and the second is from 36.4 to 40.2 GHz with peak gain of 4.54 dB, 4.21 dB in the first and second frequencies respectively. The simulated radiation efficiency for the first and second frequencies is 94% and 96.6%, respectively. There are some small discrepancies between simulated and measured findings due to the fabrication and measurement equipment.

Effective dielectric permeability and electrical conductivity of polycrystalline PbTe films with disturbed stochiometry

This paper presents the study of the effective dielectric constant and electrical conductivity of polycrystalline PbTe films with disturbed stoichiometry. It is shown that superstoichiometric additions of Te and Pb within the limits of solubility by doping with PbTe contribute to a change in a wide range of concentrations of electrically active impurities and, consequently, to an increase in the dielectric constant (ɛ), electrical conductivity (σ) and absorption coefficient (α), in addition, the excess of these components strongly affects the amount of polarization.

Laminar Burning Velocity of Lean Methane/Air Flames under Pulsed Microwave Irradiation

Laminar burning velocity of lean methane/air flames exposed to pulsed microwave irradiation is determined experimentally as part of an effort to accurately quantify the enhancement resulting from exposure of the flame to pulsed microwaves. The experimental setup consists of a heat flux burner mounted in a microwave cavity, where the microwave has an average power of up to 250 W at an E-field in the range of 350–380 kV/m. Laminar burning velocities for the investigated methane/air flames increase from 1.8 to 12.7% when exposed to microwaves. The magnitude of the enhancement is dependent on pulse sequence (duration and frequency) and the strength of the electric field. From the investigated pulse sequences, and at a constant E-field and average power, the largest effect on the flame is obtained for the longest pulse, namely 50 μs. The results presented in this work are, to the knowledge of the authors, the first direct determination of laminar burning velocity on a laminar stretch-free flame exposed to pulsed microwaves.

Preparation and Study the Electrical and Optical Properties for (PVA-PEG-Sr2O3) Nanocomposites

In the presented work, the optical and electrical properties of composite materials (PVA-PEG-Sr2O3) were measured, as the electrical properties were verified at various frequencies in range of 100 Hz-6 MHz. In addition, the experimental results showed that the increase in frequency causes a reduction in the dielectric loss (δ) and dielectric constant (ɛ), and there is an increase in ɛ due to the increase in the content of antimony oxide (Sr2O3). It increases with increasing frequency and decreases with increasing Sr2O3 content in PVA-PEG-Sr2O3 compounds, the result of the optical properties of the nanoparticles (PVA-PEG-Sr2O3) showed that the values transmittance and energy gap were reduced with the increases in the concentrations of Sr2O3 NPs, whereas the values related to extinction coefficient, absorption coefficient, optical conductivity, refractive index, and dielectric constant (imaginary, real) were increased with increase in the concentration of Sr2O3 NPs.

Can the results of quantum refinement be improved with a continuum-solvation model?

Quantum refinement has repeatedly been shown to be a powerful approach to interpret and improve macromolecular crystal structures, allowing for the discrimination between different interpretations of the structure, regarding the protonation states or the nature of bound ligands, for example. In this method, the empirical restraints, used to supplement the crystallographic raw data in standard crystallographic refinement, are replaced by more accurate quantum mechanical (QM) calculations for a small, but interesting, part of the structure. Previous studies have shown that the results of quantum refinement can be improved if the charge of the QM system is reduced by adding neutralizing groups. However, this significantly increases the computation time for the refinement. In this study, we show that a similar improvement can be obtained if the original highly charged QM system is instead immersed in a continuum solvent in the QM calculations. The best results are typically obtained with a high dielectric constant (ɛ). The continuum solvent improves real-space Z values, electron-density difference maps and strain energies, and it normally does not affect the discriminatory power of the calculations between different chemical interpretations of the structure. However, for structures with a low charge in the QM system or with a low crystallographic resolution (>2 Å), no improvement of the structures is seen.

A Novel Metamaterial Inspired 2nd Iteration Koch Fractal Antenna for Wi-Fi, WLAN, C band and X band Wireless Communications

The rapid advancements in wireless technology desires compact, miniaturized, multiband and ultra wideband antennas. Fractal antennas have been proved as a source for fulfilling these demands. In this paper a 2nd order Koch fractal antenna of size 29.6 × 35.7mm2 designed on FR4-epoxy substrate material of dielectric constant (ɛr) 4.4 with a height of 1.6mm. This antenna is named as ANTENNA-1. To increase this antenna’s performance a meta material unit cell has been placed on the ground plane to serve multi band applications and is named as ANTENNA-2, which is the proposed antenna in this paper. The simulations have been carried out for both the antennas using ANSYS HFSS tool over the frequency sweep of (1-12GHz). The simulation results of proposed antenna producing 7 frequency bands which serves Wi-Fi, WLAN, C-band, and X band wireless communications. The simulation results like return loss, VSWR values have a good matching with the measured return loss, VSWR results of the fabricated antenna

Design of dual band slotted reconfigurable antenna using electronic switching circuit

This paper proposes a dual band reconfigurable microstrip slotted antenna for supporting the wireless local area network (WLAN) and worldwide interoperability for microwave access (WiMAX) applications, providing coverage where both directive and omni-directive radiations are needed. The design consists of a feedline, a ground plane with two slots and two gaps between them to provide the switching capability and a 1.6 mm thick flame retardant 4 (FR4) substrate (dielectric constant Ɛ=4.3, loss tangent δ=0.019), modeling an antenna size of 30x35x1.6 mm3. The EM simulation, which was carried out using the connected speech test (CST) studio suite 2017, generated dual wide bands of 40% (2-3 GHz) with -55 dB of S11 and 24% (5.2-6.6 GHz) higher than its predecessors with lower complexity and -60 dB of S11 in addition to the radiation pattern versatility while maintaining lower power consumption. Moreover, the antenna produced omnidirectional radiation patterns with over than 40% bandwith at 2.4 GHz and directional radiation patterns with 24% bandwith at the 5.8 GHz band. Furthermore, a comprehensive review of previously proposed designs has also been made and compared with current work.

Solvent dielectric effect on electrochemical properties of 3,4-propylenedioxythiophene

The present study is focused on the electrochemical properties of poly(3,4-propylene­dioxy­thiophene) (Poly(ProDOT)), electrocoated on the single carbon-fiber microelectrode (SCFME) in different electrolytic media, with different solvent dielectric constants (35.9, 41.7, 47.5, 53.3, 59.1 and 64.9). The highest deposition charge density of 24.49 mC cm-2 and the highest specific capacitance of 23.17 mF cm-2 were obtained for Poly(ProDOT) synthesized in a medium with the lowest solvent dielectric constant (e = 35.9). Electrochemical impedance spectroscopy (EIS) results of Poly(ProDOT) coated SCFME measured at open circuit potential showed continuously increased impedance magnitudes as ε was increased from 35.9 to 59.1. For all films, almost capacitive impedance responses at lower frequencies at least were obtained. The highest capacitance was observed for the polymer film synthesized in the medium of e = 35.9. The impedance of this film was also measured in different solvent mixtures with different dielectric constants at open circuit potential.

Compact Dualband Mimo Antenna for Wireless Communication

A compact dual band two element planar multiple input and multiple output (MIMO) antenna system is designed for Wireless applications. The Proposed design consists of two printed F shape slot radiators which are arranged symmetrically on the upper layer of the substrate. A patch with I shaped strip on the ground plane helps in reducing the mutual coupling between radiators and A circular ring slot is placed in ground plane to improve the bandwidth of antenna. The proposed module is designed on Fr-4 substrate whose dielectric constant (ɛr) is 4.4. The results show that the MIMO antenna has a resonance frequency at 2.2GHz, which is suitable for Wireless communications system applications and comes with a mutual coupling(s12) less than − 15 dB and the envelop correlation coefficient (ECC) did not exceed 0.02 in the entire operating band of the MIMO antenna part.