Research on the stability of the 3D frame on coral foundation subjected to impact load

This article presents an application of the finite element method (FEM) for the stability analysis of 3D frame (space bar system) on the coral foundation impacted by collision impulse. One-way joints between the rod and the coral foundation are described by the contact element. Numerical analysis shows the effect of some factors on the stability of the bar system on coral foundation. The results of this study can be used for stability analysis of the bar system on coral foundation subjected to sea wave load

Research and Design of an X-Band UHF Power Amplifier

Introduction. A method for designing power amplifiers for use in the transmitting channels of X-band transceiver modules is investigated. The design process was aimed at optimizing the relationship between the basic amplifier characteristics, including the operating frequency band, output power level, output linearity, high harmonics suppression, etc.  Aim. Investigation of a method for designing an X-band UHF power amplifier, which is capable of optimizing the relationship between its main characteristics.  Materials and methods. Theoretical calculations were combined with experimental studies into the design of a UHF power amplifier. The stages of the design process are described in detail, including major ideas, principal circuits, and strip circuits. Evaluations were conducted using the Keysight ADS high frequency circuit simulation tool.  Results. A method for designing X-band UHF power amplifiers on the basis of a close combination of theory, simulation, and experimental adjustment was described in detail.  Conclusion. A prototype of an X-band PA was developed; an approach to developing a methodology for manufacturing, measuring, and testing X-band PAs is described.Introduction. A method for designing power amplifiers for use in the transmitting channels of X-band transceiver modules is investigated. The design process was aimed at optimizing the relationship between the basic amplifier characteristics, including the operating frequency band, output power level, output linearity, high harmonics suppression, etc.  Aim. Investigation of a method for designing an X-band UHF power amplifier, which is capable of optimizing the relationship between its main characteristics.  Materials and methods. Theoretical calculations were combined with experimental studies into the design of a UHF power amplifier. The stages of the design process are described in detail, including major ideas, principal circuits, and strip circuits. Evaluations were conducted using the Keysight ADS high frequency circuit simulation tool.  Results. A method for designing X-band UHF power amplifiers on the basis of a close combination of theory, simulation, and experimental adjustment was described in detail.  Conclusion. A prototype of an X-band PA was developed; an approach to developing a methodology for manufacturing, measuring, and testing X-band PAs is described

Water-phase synthesis of cationic silica/polyamine nanoparticles

Functionalizing surfaces with amine groups through the hydrolytic condensation of aminotrialkoxysilanes is a typical approach when modifying silica particles for use in bioimaging, enzyme immobilization, and other applications. This processing step can be eliminated if amine-functionalized silica particles are directly prepared without using aminotrialkoxysilanes. Here, a one-pot, ambient-condition, water-phase method to synthesize silica-based nanoparticles (NPs) that present surface amine groups is described. The formation mechanism involves the electrostatic crosslinking of cationic polyallylamine hydrochloride by citrate anions and the infusion of the formed polymer/salt aggregates by silicic acid. The particles were unimodal with average diameters in the range of 40 to 100 nm, as determined by the size of the templating polymer/salt aggregates. Colorimetric analysis using Coomassie brilliant blue and zeta potential measurements confirmed the presence of surface amine groups of the hybrid silica/polymer NPs. Surface charge calculations indicated the hybrid NPs had a lower amine surface density than aminopropyltriethoxysilane-functionalized silica (0.057 #/nm 2 vs. 0.169 #/nm 2 at pH 7)

Dynamic stability analysis of laminated composite plates with piezoelectric layers

Research on the stability to determine the critical value of structures is a complex issue but of real significance. Piezoelectric composite plate is one of the structures which have the ability to control the mechanical behaviors under loads. One of the prominent capabilities of this structure is the ability to control its vibration and stability. Using the finite element method (FEM) and construction calculation program in Matlab, the authors analyzed the elastic stability of piezoelectric composite plates under dynamic in-plane loads, taking into account damping properties of the structure. Critical loads and other factors affecting the stability of the plate are investigated

Does more working women result in more single men?

The following report is going to discuss whether the relationship in the title exists. The theoretical approach suggests that both possibilities can happen due to the simple assumptions of the economic theories used in this research. Evidence shows a clear trend for a positive relationship between women’s working hours and the number of single men. However, the trend weakens over the time, possibly due to stabilisation of women’s wages more recently

Dynamic Analysis of Mindlin Plates Resting on a Viscoelastic Foundation Subjected to Moving Loads During Abrupt Braking using Moving Element Method

The paper proposes a new computational approach using the moving element method (MEM) for simulating the dynamic responses of Mindlin plate resting on a viscoelastic foundation subjected to moving loads during abrupt braking. In this approach, the governing equations as well as the plate element mass, damping and stiffness matrices are formulated in a convected coordinate in which the origin is attached to the applied point of the moving load. Thus, the proposed method simply treats the moving loads as ‘stationary’ at the nodes of the plate to avoid updating the locations of moving loads due to the change of the contact points on the plate. The interaction between the moving load and the plate during abrupt braking is accounted for through the vertical force and tangential wheel-pavement friction force. The effects of wheel sliding, load deceleration magnitude, friction coefficient, and plate thickness on the dynamic responses of plate are investigated