A seismic retrofit method by connecting viscous dampers for microelectronics factories

The implementation of viscous dampers to microelectronics factories has been previously proved not to affect the micro‐vibration of the factories in operation so that the vibration‐sensitive manufacturing process will not be interfered. Therefore, a seismic retrofit strategy which employs the viscous dampers installed in between the exterior and interior structures of the ‘fab’ structure is proposed in the study. The design formulas corresponding to the proposed retrofit method are derived using the non‐proportional damping theory. Based on the study, it is found that the added damping ratio to the fab structure depends greatly on the frequency ratio of the two structures in addition to the damping coefficients of the added dampers. Outside the bandwidth of the frequency ratio in which the added damping ratio is very sensitive to the variation of the frequency ratio, the added damping ratio can be well captured using the classical damping theory. Copyright © 2007 John Wiley & Sons, Ltd.     

Quartz dissolution experiments at various pH, temperature and stress conditions: CLSM and ICP-AES investigations

To understand the effects of temperature, pH and mechanical stress on the pressure dissolution of quartz, two experiments using monocrystalline quartz samples were conducted. The first was a closed-fluid experiment to investigate the effect of pH, and the second was a flow-through experiment to investigate stress and temperature effects. To initiate the pressure dissolution, a pair of samples was immersed in a solution with a prescribed pH. The samples were stressed mechanically by pressing one sample against the other. In the closed-fluid experiments, the pH of the solution was fixed to 7, 9, 11 and 13, the applied stress was approximately 200 MPa and temperature 25°C. The flow-through experiments were conducted at three different temperatures (35, 50 and 75°C) at the same pH 11.7. The value of the applied stress was 7.32, 13.72, 21.42 or 25.27 MPa. During each of these dissolution tests, the solution was regularly sampled and analyzed by an Inductively Coupled Plasma-Atomic Emission Spectrometry technique to measure Si-concentration. With the measured Si-concentration, a dissolution rate constant was computed the different pH, stress and temperature conditions. The rate constant is proportional to pH, stress and temperature, as indicated in the literature. It should be noted that the rate constant for the highest stress (200 MPa) was considerably greater than for the other cases. In addition, island-channel patterns characterized by micro-cracks a few nanometers in length were seen on the dissolved parts of the samples. The findings and the measured data in this paper may be useful for the future development of theoretical models for pressure dissolution and its validation.     

Shear wave velocity and attenuation structure for the shallow crust of the southern Korean peninsula from short period Rayleigh waves

We analyzed the short period Rayleigh waves from the first crustal-scale seismic refraction experiment in the Korean peninsula, KCRUST2002, to determine the shear wave velocity and attenuation structure of the uppermost 1 km of the crust in different tectonic zones of the Korean peninsula and to examine if this can be related to the surface geology of the study area. The experiment was conducted with two large explosive sources along a 300-km long profile in 2002. The seismic traces, recorded on 170 vertical-component, 2-Hz portable seismometers, show distinct Rayleigh waves in the period range between 0.2 s and 1.2 s, which are easily recognizable up to 30–60 km from the sources. The seismic profiles, which traverse three tectonic regions (Gyeonggi massif, Okcheon fold belt and Yeongnam massif), were divided into five subsections based on tectonic boundaries as well as lithology. Group and phase velocities for the five subsections obtained by a continuous wavelet transform method and a slant stack method, respectively, were inverted for the shear wave models. We obtained shear wave velocity models up to a depth of 1.0 km. Overall, the shear wave velocity of the Okcheon fold belt is lower than that of the Gyeonggi and Yeongnam massifs by  0.4 km/s in the shallowmost 0.2 km and by 0.2 km/s at depths below 0.2 km. Attenuation coefficients, determined from the decay of the fundamental mode Rayleigh waves, were used to obtain the shear wave attenuation structures for three subsections (one for each of the three different tectonic regions). We obtained an average value of Q_β^− 1 in the upper 0.5 km for each subsection. Q_β^− 1 for the Okcheon fold belt ( 0.026) is approximately three times larger than Q_β^− 1 for the massif areas ( 0.008). The low shear wave velocity in the Okcheon fold belt is consistent with the high attenuation in this region.     

Pargasitic-kaersutitic amphibole from a basanitic diatreme at the Rosenberg,North of Kassel (North Germany)

The tuff and basanite of Rosenberg 20 km NW of Kassel are thus far unknown occurrences of megacrysts and polycrystalline aggregates of pargasitic-kaersutitic amphibole and of xenoliths of amphibole-bearing peridotite and pyroxenite. The amphiboles precipitated successively with gradually increasing Fe/Mg from the same magma from which the basanite was ultimately derived. The amphibole fractionation commenced within the upper mantle but may have continued into higher levels within the ascending melt.Amphibole and phlogopite fractionation together caused an increased Na/K ratio in the Rosenberg basanite. The crystallization of amphibole and phlogopite is genetically interrelated with the violent eruptive nature of the Rosenberg volcano. The release of vapour during the final stage of amphibole crystallization is indicated by the existence of coarsely vesicular amphibole megacrysts.