Vibrations of a vehicle excited by real road profiles

Based on experimental data obtained from the Lublin III delivery car, we have performed a vibration analysis of the vehicle suspension system. Vertical accelerations on the left and right sides of the suspension system were measured. Experiments were carried out on three types of road surfaces: (a) asphalt, (b) sett, and (c) railway cross. The acceleration signals were examined using Fourier transform, multiscale entropy analysis and continuous wavelet transform. These methods reveal the characteristics of the vibration patterns produced by the various road surface profiles. Our results can be used to assess the efficacy of a vehicle suspension system under different road conditions.     

Strain Localization During Compressive Deformation of Mg-Gd Alloy

Metallurgical and Materials Transactions A - Strain localization occurring at advanced deformation under compression of Mg-0.28 at. pctGd alloy has been studied. The strain localization develops in...     

An arrayed waveguide grating based multiplexer and interrogator for Fabry-Perot sensors

In this paper, we propose an interrogation system capable of multiplexing four identical Fabry-Perot (FP) interferometric sensors using two wavelength-division multiplexing devices. One is a 40-channel DWDM channel monitor, the other a four-channel CWDM device. The sensors are connected to the output channels of the CWDM device in order to assign a portion of the spectrum to each sensor. The reflected spectra are then analyzed using the DWDM channel monitor. By monitoring the power incident on each of the DWDM channels, the four sensor reflection spectra can be reconstructed in software and information relating to the measurand obtained. Based on software simulations and previous laboratory experiments with single sensors, it is predicted that this system would be capable of interrogating four EFPI strain sensors simultaneously at frequencies greater than 5 kHz with a resolution of approximately 2 /spl mu//spl epsiv/ and a range of 3000 /spl mu//spl epsiv/.     

Synthesis and Magnetic Properties of Ni-Zirconia Composites

A novel method has been developed for the fabrication of composite magnetic films on various conductive substrates. Cathodic electrolytic deposition was used as the technique to obtain thin films from solutions of nickel and zirconium salts. The hydroxide deposits were converted to Ni-ZrO₂composites after sintering in reducing conditions. Deposit yield was studied in the constant current deposition mode. Deposits were evaluated using X-ray analysis and magnetic measurements. Results of dc and ac measurements performed in different magnetic fields, temperatures, and frequencies demonstrated the magnetic properties of the composites.     

The Peculiarities of Magnetic Flux Dynamics at Magnetothermal Instability in Textured Bi2Sr2CaCu2O8+δ

The magnetic flux dynamics was investigated in a textured Bi₂Sr₂CaCu₂O₈₊ sample using a miniature Hall probe placed on the surface of the superconductor. The process of magnetic flux penetration into the superconductor was found to have a complex structure and consist of two processes with different time scales. The first one has a length of tens of microseconds and is considered as locally adiabatic. The second one has a length comparable with the time of thermal diffusion. The importance of the above two processes in the development of magnetic instability is analyzed.     

New crystal plasticity constitutive model for large strain deformation in single crystals of magnesium

A new rate-dependent elastic–viscoplastic crystal plasticity constitutive model (CPCM) to simulate the large strain deformation in magnesium alloys is presented. The observed intragranular plastic deformation mechanisms of primary extension, primary contraction, and secondary extension (double) twinning are accounted for. The basal and non-basal slip systems in the parent grain, primary and double twins were also incorporated in the model. The crystallographic planes and directions of various slip and twinning systems are calculated. The slip-induced shear in the parent grain, as well as primary and secondary twinned regions are simulated. The twinning-induced shear from the primary and secondary twinned regions are also computed. In the model the texture evolution in the parent, as well as primary and secondary twinned regions are tracked. Separate resistance evolution functions for all the slip and twinning systems were considered. The interactions between various slip and twinning systems are accounted for in a comprehensive manner. Using the proposed CPCM, the plastic deformation in a magnesium single crystal in simple shear strain path is simulated. The contributions of various plastic deformation mechanisms to the macroscopic plastic deformation of the magnesium single crystal in this strain path are presented. The importance of identifying the active plastic deformation in a given strain path on a magnesium single crystal for a reliable model prediction was shown with an example.     

Magnetic crosstalk compensation for an optical current transducer

In this paper, we analyze the errors associated with magnetic crosstalk within point type, or unlinked, optical current transducers (OCTs) working in a three-phase electric current transmission systems. For many practical conductor arrangements, the magnetic crosstaIk may introduce errors unacceptable for the accuracy requirements demanded from the OCT. A solution to this problem is devised around a unique compensation method which solves, in real time, a set of linear equations, each representing the instantaneous output signal from one phase current sensor     

Single atomic layer detection of Ca and defect characterization of Bi-2212 with EELS in HA-ADF STEM

By forming a small electron probe in a scanning transmission electron microscope equipped with a high-angle annular dark-field (HA-ADF) detector, the Bi-O atomic planes in Bi2Sr2CaCu2O(8+delta) (Bi-2212) can be directly observed with the incoherent Z-contrast imaging technique. Using a combination of electron energy loss spectroscopy (EELS) and HA-ADF imaging, we were able to detect the Ca signals from individual Ca atomic planes in this structure, so that the Ca distribution could be probed within individual unit cells. This high-spatial-resolution EELS technique has been successfully applied to characterize planar defects such as the half-unit cell intergrowth of Bi-2201 on the nanometer scale. Present results show that EELS, in conjunction with high-resolution HA-ADF imaging, provides a powerful tool to study chemical and structural nature of this material on the atomic scale.     

Dynamic strain measurement using an extrinsic Fabry-Perot interferometric sensor and an arrayed waveguide grating device

In this paper, we demonstrate an interrogation system, based on an arrayed waveguide grating, capable of monitoring dynamic strain in a cantilever beam at frequencies up to 5 kHz (limited by the actuator) with a similar precision to resistive strain gauges.