Quasiperiodic forced vibrations of a beam interacting with a nonlinear spring

Summary A simply supported beam with fixed ends and an attached strongly nonlinear spring is considered. As the forced bending vibrations of the beam have moderate amplitudes, the stretching force is a nonlinear function of the deflection. The vibrations are presented as a series with respect to the modes of the beam without attachment. Applying the Bubnov-Galerkin procedure, an infinite system of ordinary differential equations is derived. Using the multiple scales method, the quasiperiodic vibrations in the region of the combination resonance are analyzed in the paper. The system vibrations, when the nonlinear spring is attached in different points, are analyzed. Applicability of the nonlinear spring for mitigation of a combination resonance is discussed.     

An investigation of the relation between the temperature dependences of the initial unbalance and the output signal of resistance strain sensor bridge circuits

The relation between the initial unbalance and the output signal of bridge circuits when acted upon simultaneously by the physical factor being measured and the temperature of the surroundings when the bridge is supplied from a voltage or current source is investigated. Analytic relations are obtained which explain the temperature dependence of the useful output voltage under external physical action. __________ Translated from Izmeritel’naya Tekhnika, No. 1, pp. 48–49, 2007.     

Utilization of waste of Al - B fiber composites for obtaining new powder and sintered materials

Composite powder based on AlB has been obtained by crushing pieces of industrial-waste Al - B fiber composite material at room temperature. The original design of a high precision microhardness tester made it possible to estimate the properties of powder particles both in the near-surface layers and under them. The aluminum fraction in the powder was established to represent a new structurally nonhomogenous material with increased microhardness (1.5 GPa), which grows up to 4 GPa in the near-surface layers. This is caused by formation of defects and stable oxides on external and internal interfaces in the aluminum matrix during crushing. To optimize the process of AlB powder sintering, adhesion on clean and real Al - B and Al/Al interfaces at various temperatures was investigated. By sintering at 910 K, new ceramic materials have been obtained with a density of 2200 kg/m³ and a strength of 90 MPa.     

Floor free 10-Gb/s transmission with directly modulated GaInNAs-GaAs 1.35-/spl mu/m laser for metropolitan applications

Among the new semiconductor materials for telecom devices, the GaInNAs-GaAs structure presents interesting properties for low-cost applications, like high differential gain and high T/sub 0/. Another key aspect of the performance is the behavior of the GaInNAs-GaAs based lasers under high bit rate direct modulation. Here, we demonstrate the dynamic capabilities of GaInNAs-GaAs three-quantum-well ridge structure through 2.5-Gb/s directly modulated laser emission and transmission on standard fiber, in the temperature range 25/spl deg/C-85/spl deg/C. Besides transmission is demonstrated up to 10 Gb/s at 25/spl deg/C on the same fiber, without penalty and bit-error-rate floor.     

Method for the Microwave Measurement of Carrier Lifetime in Lightly Doped Silicon Ingots

A further investigation is conducted into a new microwave method for evaluating bulk lifetime in silicon ingots     

Glyconanoparticle-DNA interactions: an atomic force microscopy study.

Glyconanoparticles which present carbohydrate and amino groups motifs at their surface were produced. These particles were highly stable and soluble in aqueous solutions. The presence of the carbohydrate groups also allowed the inclusion of more strongly binding groups, without affecting solubility. The binding of a model DNA, plasmid by these nanoparticles was studied by atomic force microscopy, transmission electron microscopy, and gel electrophoresis. Significant differences between the nanoparticles based on their affinities for the DNA were found, with implications for their potential use as nonviral gene delivery agents.     

Structure modification of rapidly solidified Al-11 wt% Si alloy by the addition of 2 wt% Fe

An investigation of the structure formation of as-cast Al-11 wt% Si (AlSi11) and Al-11 wt% Si-2 wt% Fe (AlSi11Fe2) rapidly solidified (RS) ribbons is performed. Ribbon samples are examined in detail using Auger electron spectroscopy (AES) and transmission electron microscopy (TEM). A nanoscale thickness layer of Si-precipitations, at both Al-grains boundary and oxide/Al-matrix interface, is found to be characteristic for “pure” AlSi11 ribbons. For Fe-doped ribbons, this layer comprises Fe-containing phase also, which appears to possess amorphous nature and is situated between the Si-grains and Al-matrix. A possible mechanism of altering the thermally activated volume diffusion of elements, due to the effect of Fe on the structure modification, is speculated based on the obtained results.