Stability and Strength of Rigid and Semirigid Plane Frameworks

A computational technique for incorporating stability and strength into the analysis of plane frameworks is presented. The procedure for computing critical and/or collapse loads and for identifying the corresponding failure mode is outlined. The analysis is based on nonlinear kinematic relations and linearly elastic material behavior except at the plastic hinges—concentrated plasticity. The connections can be treated either as rigid or as flexible. The supports, in general, contain rotational restraints. The developed solution methodology is applicable to all multistory‐multibay orthogonal frames. The examples analyzed in the paper include: (1) A single‐story‐two‐bay frame with rigid joint connections; (2) a single‐story‐three‐bay frame with flexible joint connections; (3) a two‐story‐single‐bay frame with both rigid and flexible joint connections; and (4) a three‐story‐two‐bay frame with rigid joint connections. In all cases the loading consists of a symmetric distribution of concentrated loads on the beams, applied at the midspan positions and at or near the beam‐to‐column joints. The effect of several geometric and structural parameters is assessed.     

Influence of selected water soluble carbohydrates on the dissolution profile of prednisolone

The utilization of three water soluble carbohydrates as carrier to improve the dissolution rate of prednisolone was studied. Coprecipitates and physical mixtures of the drug and the carriers in three different proportions were prepared and their dissolution profile was compared with the dissolution profile of the pure drug. The remarkably fast and erratic dissolution of prenisolone observed from the coprecipitates was possible due to the conversion of prednisolone into its metastable or amorphous form durning the coprecipitation process. The dissolution rate of the drug from the physical mixtures was much higher than from the pure drug itself. Effect of aging of the coprecipitate on the dissolution profile showed an increasing tendency of the dissolution curve to match with that of the corresponding physical mixture.     

Application of Magnetic Susceptibility to Study Low Iron Substitution in Tricalcium Aluminate

The magnetic susceptibilities of the tricalcium aluminate prepared containing 0.5, 1, or 2 wt% FeC₂O₄ or Fe₂O₃ before firing were measured at different temperatures and different magnetic field intensities. The Curie temperature of each compound is determined from the magnetic susceptibility temperature curves. The values of the effective magnetic moments were calculated from the experimental data for the different compounds. The variations in the magnetic properties and the magnetic constants with the type and concentration of iron added to C₃A confirm that the magnetic susceptibility measurements could be considered a good tool to estimate the solubility limit of iron in different forms in C₃A. Our data confirm also the previous data of IR measurements for such samples at low iron concentrations.     

Avalanche behavior of low-voltage power MOSFETs

This letter addresses the behavior of low voltage power MOSFETs under avalanche, with a paralleling point of view. It is shown that during avalanche, up-to-date technology MOSFET transistors exhibit a resistance far in excess of their on-state resistance (R/sub DSon/). A novel test setup is proposed to measure "avalanche" resistance. A simple model of breakdown voltage is then proposed. It becomes possible to perform fast simulations using this model to study current balance between paralleled transistors under avalanche operation. It is shown that considering avalanche resistance reduces the influence of breakdown voltage mismatches and allows for better current sharing.     

Assessment of Equity and Adequacy of Water Delivery in Irrigation Systems Using Remote Sensing-Based Indicators in Semi-Arid Region, Morocco

The irrigation performance criteria of equity and adequacy are of primary concern for irrigation managers. The input data required at various scales to assess irrigation performance, often not available, need costly intensive field campaigns. Remote sensing techniques, used to directly estimate crop evapotranspiration (ETc), became recently an attractive option to assess irrigation performance from individual fields to irrigation scheme or river basin scale. In this study, ETc maps were obtained by combining the FAO-56 dual approach with relationships between crop biophysical variables and NDVI (Normalized Difference Vegetation Index), using high spatial resolution time series of SPOT and Landsat images. This approach was applied for 2002/2003 growing season in Haouz plain, Morocco. Remote sensing-based indicators, reflecting equity and adequacy of the irrigation water delivery were estimated. Adequacy was determined according to Relative Irrigation supply (RIS), Depleted Fraction (DF) and Relative Evapotranspiration (RET) and equity according to the coefficient of variation of ETc. The analysis of these indicators exhibits a great variability among fields. Variability in irrigation performance at all levels, associated factors and possible improvements are discussed. This study demonstrates how remote sensing-based estimates of water consumption provide better estimates of irrigation performance at different scales than the traditional field survey methods.     

Dielectric properties of irradiated polymer/multiwalled carbon nanotube and its amino functionalized form

The polymer/multiwalled carbon nanotube [poly(vinyl alcohol) (PVA)/carboxyethyl acrylate (CEA)]‐multiwalled carbon nanotube (MWCNT) and its amino functionalized (PVA/CEA)‐MWCNT‐NH₂ nanocomposite samples were successfully synthesized by the chemical method in the form of films. The samples were irradiated with gamma‐ray doses of 50 and 100 kGy and with ion beam fluence of 2.5 × 10¹⁸ and 3.75 × 10¹⁸ ions cm^?2. The prepared nanocomposite samples were characterized using X‐ray diffraction and thermogravimetric analysis. The X‐ray diffraction and thermogravimetric analysis confirm the existence of the chemical crosslinking occurred in the polymer compositions. The AC electrical conductivity, electrical modulus, dielectric constant, and dielectric loss in the frequency range 10²–10⁶ Hz are measured at room temperature. The electrical conductivity is increased with MWCNT doping, gamma‐irradiation, and by ion beam irradiation. A comprehensive analysis of the results revealed that dielectric properties are improved due to the induced physicochemical changes and conductive networks induced by ion beam irradiation. The behavioral effect of these embedded nanoparticles in a PVA matrix on the microstructural, dielectric, and electric properties is analyzed for possible device applications. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46647.     

An efficient and lightweight multi‐scroll chaos‐based hardware solution for protecting fingerprint biometric templates

This paper presents a new efficient and lightweight approach for enhancing the security of biometric models, namely, fingerprint templates, against possible attacks. The proposed design is based on Vernam stream cipher in which the key generator is designed in the hardware manner. The designed cryptosystem consists of using multi‐scroll chaotic system that is characterized by a large key space and can be generated N×N grid multi‐scroll attractors, with a good behavior of chaotic dynamic. The hardware approach is carried out through describing Euler method by VHDL. Field‐programmable gate array (FPGA) experimental results validate the developed architecture while still providing a good compromise between hardware resources and performance. Indeed, security analysis also shows that the designed encryption algorithm is robust against statistical, brute force, and entropy attacks. Therefore, it can be considered as a lightweight security solution, which could be very useful in many embedded applications namely securing biometric authentication systems.     

Solving complex PIDE systems for pricing American option under multi-state regime switching jump–diffusion model

Based on exponential time differencing approach, an efficient second order method is developed for solving systems of partial integral differential equations. The method is implemented to solve American options under multi-state regime switching with jumps. The method is seen to be strongly stable ($L$-stable) and avoids any spurious oscillations caused by non-smooth initial data. The predictor–corrector nature of the method makes it highly efficient in solving nonlinear PIDEs in each regime with different volatilities and interest rates. Penalty method approach is applied to handle the free boundary constraint of American options. Numerical results are presented to illustrate the performance of the method for American options under Merton’s jump–diffusion models. Padé approximation of matrix exponential functions and partial fraction splitting technique are applied to construct computationally efficient version of the method. Efficiency, accuracy and reliability of the method are compared with those of the existing methods available in the literature.     

Pseudo Almost Automorphic Solutions of Recurrent Neural Networks with Time-Varying Coefficients and Mixed Delays

In this paper, existence, uniqueness and global exponential stability of pseudo almost automorphic solutions for a class of recurrent neural networks with time-varying coefficients and mixed delays are established by employing the fixed point theorem and differential inequality. Numerical example with graphical illustration is given to illuminate our main results.