Low-voltage low-power Gm-C filters: a modified configuration for improving performance

In this paper, after addressing the effect of finite output impedance of Gm cells on the performance of Gm-C filters, a modified configuration suitable for low-voltage operation is presented. In the proposed architecture, to efficiently increase the output impedance, body-driven impedance boosting is employed. The circuit-level topology of Gm cells is modified in order to increase the output impedance with minimized power consumption. To show the effectiveness of the proposed scheme, a 0.9-V 5-th order Butterworth low-pass filter with 8 MHz cutoff frequency is designed and simulated in 90-nm CMOS technology. Employing the proposed technique, power consumption is reduced from 0.7 mW to 0.5 mW.     

Structural,morphologic and optical characterization of In(2−x)Al x S3

Aluminum-doped indium sulfide thin films are deposited on glass by spray pyrolysis technique. The structure and the surface morphology of these films were characterized by X-ray diffraction and atomic force microscopy. The effects of aluminum ratio z and substrate temperature T _s, on the film structure and grain size are discussed. The influence of aluminum ratio on surface morphology is revealed by scanning electron microscope. Besides, energy dispersive spectrometry technique is used to compare atomic aluminum concentration in the film with aluminum ratio z in spray solution. Optical properties are studied by a spectrophotometer in the wavelength range 350–850 nm, at room temperature. Optical transmission and grain size are found to be maximal for z = 1.8 %. Moreover, band-gap energy is found to increase with aluminum ratio.     

Isoperimetric Inequalities for a Wedge-Like Membrane

For a wedge-like membrane, Payne and Weinberger proved in 1960 an isoperimetric inequality for the fundamental eigenvalue which in some cases improves the classical isoperimetric inequality of Faber–Krahn. In this work, we introduce “relative torsional rigidity” for this type of membrane and prove new isoperimetric inequalities in the spirit of Saint-Venant, Pólya–Szeg?, Payne, Payne–Rayner, Chiti, and Talenti, which link the eigenvalue problem with the boundary value problem in a fundamental way.     

Sensitivity and stability analysis on the first and second levels of efficiency score relative to data error

In data envelopment analysis (DEA), efficient decision making units (DMUs) are of primary importance as they define the efficient frontier. The current paper develops a new sensitivity analysis approach for a category DMUs and finds the stability radius for all efficient DMUs. By means of combining some classic DEA models and with the condition that the efficiency scores of efficient DMUs remain unchanged, we are able to determine what perturbations of the data can be tolerated before efficient DMUs become inefficient. Our approach generalizes the conventional sensitivity analysis approach in which the inputs of efficient DMUs increase and their outputs decrease, while the inputs of inefficient DMUs decrease and their outputs increase. We find the maximum quantity of perturbations of data so that all first level efficient DMUs remain at the same level.     

Sulfamic acid immobilized on amino‐functionalized magnetic nanoparticles: A new and active magnetically recoverable catalyst for the synthesis of N‐heterocyclic compounds

Sulfamic acid immobilized on amino‐functionalized magnetic nanoparticles (MNPs/DETA‐SA) was successfully fabricated and characterized using various techniques. Diameters of approximately 15 nm for the MNPs/DETA‐SA were observed from scanning electron microscopy images. The as‐fabricated nanocomposite was applied as an efficient and magnetically reusable catalyst for the synthesis of 2,3‐dihydroquinazoline‐4(1H)‐one and polyhydroquinoline derivatives. All products were obtained in good to excellent yields. Recovery tests confirm that the catalyst can be readily recovered using an external magnet and reused many times without significant loss of its catalytic activity.     

Zirconium oxide complex‐functionalized MCM‐41 nanostructure: an efficient and reusable mesoporous catalyst for oxidation of sulfides and oxidative coupling of thiols using hydrogen peroxide

Zirconium oxide complex‐functionalized mesoporous MCM‐41 (Zr‐oxide@MCM‐41) as an efficient and reusable catalyst is reported for the oxidation of sulfides into sulfoxides using hydrogen peroxide (H₂O₂) as the oxidant, with short reaction times in good to excellent yields at room temperature under solvent‐free conditions. Also, a simple and efficient method is reported for the oxidative coupling of thiols into corresponding disulfides in good to high yields using H₂O₂ as oxidant in the presence of Zr‐oxide@MCM‐41 as recoverable catalyst in ethanol at room temperature. A series of sulfides and thiols possessing functional groups was successfully converted into corresponding products. After completion of reactions the catalyst was easily separated with simple filtration from the reaction mixture and reused for several consecutive runs without significant loss of catalytic efficiency. The mesoporous catalyst was characterized using Fourier transform infrared spectroscopy, Brunauer–Emmett–Teller surface area measurements, X‐ray diffraction, transmission and scanning electron microscopies, energy‐dispersive X‐ray spectroscopy and thermogravimetric analysis. Copyright © 2015 John Wiley & Sons, Ltd.     

A linear programming approach to test efficiency in multi-objective linear fractional programming problems

In a multi-objective linear fractional programming problem (MOLFPP), it is often useful to check the efficiency of a given feasible solution, and if the solution is efficient, it is useful to check strong or weak efficiency. In this paper, by applying a geometrical interpretation, a linear programming approach is achieved to test weak efficiency. Also, in order to test strong efficiency for a given weakly efficient point, a linear programming approach is constructed.     

Green Function Bounds and Parabolic Potentials on a Half-Space

By proving a lower and an upper bound for Green's function of certain parabolic operators with Lipschitz coefficients in 0\} {\text{ and }}0 < T < + \infty $$ " align="middle" border="0"> , we give a characterization of the associated parabolic potentials and we study in a last part the boundary behaviour of these potentials for n=1.