Thermal-imaging technologies for detecting damage during high-cycle fatigue

A high-speed and high-sensitivity thermographic-infrared (IR) imaging system has been used for nondestructive evaluation of specimen-temperature evolutions during high-cycle fatigue experiments. The relationship among the temperature, stress-strain state, and fatigue behavior is discussed. Both thermodynamics and heat-transfer theories are applied to model and quantify the observed temperature variations during fatigue. The predicted and measured temperature evolutions and inelastic strains during fatigue were found to be in good agreement. During fatigue experiments, in-situ observations as well as qualitative and quantitative analyses of Lüders-band evolutions, crack propagation, plastic zones, and final fracture have been performed by thermography, which can open up wide applications of thermography in detecting the in-situ heat-related processes, including mechanical damages and phase transformations, of materials and structural components.     

Fatigue crack growth behavior of pressure vessel steels and submerged arc weldments in a high-temperature pressurized water environment

The fatigue crack growth rate (FCGR) properties of SA508 C1 2a and SA533 Gr A C1 2 pressure vessel steels and the corresponding automatic submerged are weldments were developed in a high-temperature pressurized water (HPW) environment at 288 °C (550°F) and 7.2 MPa (1044 psi) at load ratios of 0.02 and 0.50. The HPW enviromment FCGR properties of these pressure vessel steels and submerged arc weldments were generally conservative, compared with the approrpriate American Society of Mechanical Engineers (ASME) Section XI water environmental reference curve. The growth rate of fatigue cracks in the base materials, however, was considerably faster in the HPW environment than in a corresponding 288°C (550°F) base line air environment. The growth rate of fatigue cracks in the two submerged are weldments was also accelerated in the HPW environment but to a significantly lesser degree than that demonstrated by the corresponding base materials. In the air environment, fatigue striations were observed, independent of material and load ratio, while in the HPW environment, some intergranular facets were present. The greater environmental effect on crack growth rates displayed by the base materials, as compared with the weldments, was attributed to a different sulfide composition and morphology.     

Temperature stabilization of ferrimagnetic resonance field in epitaxial YIG by Ga,La substitution

An impediment to the use of epitaxial YIG (yttrium iron garnet) in microwave devices has been the drift of the ferrimagnetic resonance field with temperature. This drift arises from the temperature sensitivity of the demagnetizing and anisotropy fields. By substituting Ga for some of the Fe and La for some of the Y in liquid phase epitaxial YIG, the demagnetizing and anisotropy field contributions to the drift were made self compensating. Temperature stability was thus achieved in perpendicular resonance. In parallel resonance there was a substantial reduction in drift.     

Cardiac tamponade in Taiwan

We describe two sibs with chorioretinal dystrophy, hypogonadotrophic hypogonadism, and cerebellar ataxia, Boucher-Neuh?user syndrome, a rare but distinct pleiotropic single gene disorder with an autosomal recessive pattern of inheritance. The cases presented illustrate that this syndrome is still poorly recognised. We provide a review and analysis of previously reported cases and the differential diagnosis, which might aid in the identification of additional cases.     

Corrosion fatigue crack propagation testing with the KRAK-GAGE® in salt water

The application of a relatively new, thin-film bondable transducer, commercially available under the name KRAK-GAGE®2, was evaluated for corrosion fatigue crack propagation tests in a sea water (3.5%NaCl) environment at ambient temperature on an HY 80 steel. Fatigue crack growth data generated by this method are shown to be consistent with those obtained by the compliance method and the commonly used optical/visual measurements. Thus, this new instrumentation system appears to be a valuable addition for corrosion fatigue crack growth testing. Furthermore, test data acquisition and analysis of the KRAK-GAGE and the compliance method were computer automated, which results in considerable cost savings for such customarily labor intensive fatigue crack propagation experiments. Additionally, the FRAC-TOMAT/KRAK-GAGE instrumentation system can be utilized for direct test machine control, permitting completely automated fatigue crack growth testing.     

Reference model selection and adaptive control for induction motordrives

An adaptive model-following speed controller for induction motor drives is proposed and implemented. This adaptive controller is easy to implement since, for the controlled plant, only the output signal is fed back. In order to choose a reference model with the desired drive dynamic behavior, a two-degree-of-freedom (2-DOF) controller is designed, using a systematic procedure based on the prescribed drive specifications. The reference model of the adaptive system is chosen as the transfer function of the controlled drive system by the 2-DOF controller in the nominal case. An adaptation signal is augmented to let the prescribed specifications be maintained under a wide range of operating conditions     

C + L-band hybrid amplifier using FBGs for dispersion compensation and power equalisation

A serial type, C+L-band hybrid amplifier based on a single pump laser diode is proposed. Dispersion management and gain equalisation among C+L-band channels are realised simultaneously. Pump reflectors and double-pass schemes are used to increase the pump slope efficiency. The power variation is reduced from 6.5 to 0.2 dB among C + L band channels.