A hybrid electronically coupled current comparator

A new versatile electronically coupled current comparator is presented in the paper. Its simpler design is more convenient for manufacturing yet it retains high accuracy in either manual or automated version. It provides a resolution of one part in 10/sup 6/ and has an estimated uncertainty less than 5/spl middot/10/sup -6/ in magnitude and less than 5 /spl mu/rad in phase at power frequencies.     

Electromechanical bending response of PZT/CNT-based polymer laminates subjected to concentrated load

This paper presents the electromechanical behavior of piezoelectric/carbon nanotube (CNT)-based polymer laminates under three-point bending. The laminate was fabricated using thin lead zirconate titanate (PZT) and multi-walled carbon nanotube (MWNT)-based polycarbonate layers. The three-point bending tests were conducted on the PZT/MWNT-based polycarbonate laminates, and the dependence of the displacement and output voltage due to mechanical loads on the nanotube content and the material dimensions were measured and discussed. The output power was then calculated. This study showed that the piezoelectric/CNT-based polymer laminates can generate power without external load resistance.     

A new algorithm for explicit adaptation of time delay

By using an adaptive technique similar to the one developed by Etter and Stearns (1981), a novel constrained algorithm for explicit time delay estimation (TDE) is derived. The adaptive process provides an unbiased delay estimate and its respective performance surface, learning characteristics and delay variance will be given. The mean-square error surface, though a function of the estimated delay only, is multimodal and proper initialization is required to guarantee global convergence. Simulation results are included to validate the convergence behavior of the TDE system     

Determination of Critical Concentrations of Silica and/or Calcia for Abnormal Grain Growth in Alumina

Minimum amounts of SiO₂ and CaO required for inducing abnormal grain growth in alumina were determined using ultrapure alumina (>99.999%) and sintering at 1900°C for 1 h in a contamination-free condition. The critical concentrations of silicon in cationic mole fractions in alumina were 300 ppm without calcium, 200 ppm with 10 ppm calcium, and 150 ppm with 20 ppm calcium. The critical concentration of calcium alone was 30 ppm. These concentrations seemed to match approximately the solubility limits reported in the literature, which suggested that the abnormal grain growth in commercially pure alumina was indeed related with the formation of a small amount of liquid phase during sintering.     

Influence of acid‐treated talc and Na2CO3 flux on mineralogical phase composition and porosity in steatite ceramics

The work aimed with the effect of preceramic mixtures containing natural talc (Tc) or acid‐treated talc (Tc‐ac) supplemented by montmorillonite (Mt) or kaolinite (Ka), and the flux Na₂CO₃ on the mineral phase composition, porosity and pore size distribution in the steatite ceramics prepared using solid state sintering at 1300°C. The samples were analyzed using X‐ray diffraction and porometry techniques and scanning electron microscopy. Application of Mt or Ka in preceramic mixtures with provided comparable results. The acidification of talc using hydrochloric acid resulted in partial release of Mg²⁺ from the structure. The ratio of SiO₂:MgO in Tc was 35:65 (wt%) and 70:30 (wt%) in Tc‐ac. Tc, clay minerals, and flux Na₂CO₃ in the MgO–Al₂O₃–SiO₂–Na₂O glass system resulted to the separation of forsterite and protoenstatite, while Tc‐ac provided crystallization of protoenstatite at the expense of clinoenstatite in highly porous ceramics. The preceramic mixtures were precursors of bimodal pore size distribution at prepared steatite ceramics.     

MIMO radar OFDM chirp waveform diversity design with sparse modeling and joint optimization

In multiple-input multiple-output radar systems, the employed waveforms should have a large time-bandwidth product, good correlation property and satisfactory ambiguity function performance. This paper proposes a orthogonal frequency division multiplexing (OFDM) chirp waveform diversity design scheme with sparse modeling and joint optimization of the waveform code matrix and amplitude matrix. First, we formulate the waveform diversity design as a mathematical optimization problem with sparse modeling and optimally design a code matrix to select the hopping frequencies for each waveform. Thereafter, the waveform amplitudes are adaptively designed by minimizing the cross-correlation peaks with genetic algorithm. The proposed method can easily generate multiple pseudo-orthogonal waveforms with satisfactory correlation and ambiguity function performance. Additionally, the impacts of waveform number, hopping frequency interval and selectable frequency index are discussed. The superiority of the proposed OFDM chirp waveform design over existing methods is verified by extensive simulation results.     

The Role of KV7.3 in Regulating Osteoblast Maturation and Mineralization

KCNQ (K_V7) channels are voltage-gated potassium (K_V) channels, and the function of K_V7 channels in muscles, neurons, and sensory cells is well established. We confirmed that overall blockade of K_V channels with tetraethylammonium augmented the mineralization of bone-marrow-derived human mesenchymal stem cells during osteogenic differentiation, and we determined that K_V7.3 was expressed in MG-63 and Saos-2 cells at the mRNA and protein levels. In addition, functional K_V7 currents were detected in MG-63 cells. Inhibition of K_V7.3 by linopirdine or XE991 increased the matrix mineralization during osteoblast differentiation. This was confirmed by alkaline phosphatase, osteocalcin, and osterix in MG-63 cells, whereas the expression of Runx2 showed no significant change. The extracellular glutamate secreted by osteoblasts was also measured to investigate its effect on MG-63 osteoblast differentiation. Blockade of K_V7.3 promoted the release of glutamate via the phosphorylation of extracellular signal-regulated kinase 1/2-mediated upregulation of synapsin, and induced the deposition of type 1 collagen. However, activation of K_V7.3 by flupirtine did not produce notable changes in matrix mineralization during osteoblast differentiation. These results suggest that K_V7.3 could be a novel regulator in osteoblast differentiation.     

Preparation of highly emissive,thermally stable,UV‐cured polysilsesquioxane/ZnO nanoparticle composites

A high molecular weight polysilsesquioxane (LPMSQ)/ZnO nanocomposite was prepared by blending a methacryl‐substituted polysilsesquioxane and PMMA‐coated ZnO nanoparticle (NP) followed by UV‐curing process. These LPMSQ/ZnO nanocomposites gave high thermal and mechanical stabilities originated from the rigid ladder structured siloxane backbone of LPMSQ. The polysilsesquioxane and surface‐modified ZnO nanoparticles showed excellent compatibility between MMA groups in LPMSQ‐ and PMMA‐capped ZnO nanoparticles to give well‐dispersed LPMSQ/ZnO nanocomposites. Mechanically pliant and flexible free standing films were obtained, and the photo and optical properties of these hybrid nanocomposites were examined. The high photoluminescent properties were maintained even after severe thermal treatments exceeding 400°C. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42333.     

Beyond the basemap of science: mapping multiple structures in research portfolios: evidence from Hungary

As a novel tool for evaluating research competences of R&D actors, science overlay maps have recently been introduced in the scientometric literature, with associated measures for assessing the degree of diversification in research profiles. In this study, we continue the elaboration of this approach: based on science overlay maps (called here m-maps), a new type of map is introduced to reveal the competence structure of R&D institutions (i-maps). It is argued, that while m-maps represent the multidisciplinarity of research profiles, i-maps convey the extent of interdisciplinarity realized in them. Upon i-maps, a set of new measures are also proposed to quantify this feature. With these measures in hand, and also as a follow-up to our previous work, we apply these measures to a sample of Hungarian Research Institutions (HROs). Based on the obtained rankings, a principal component analysis is conducted to reveal main structural dimensions of researh portfolios (of HROs) covered by these measures. The position of HROs along these dimensions then allows us to draw a typology of organizations, according to various combinations of inter- and multidisciplinarity characteristic of their performance.