Development of a PIGE-Detection System for In-situ Inspection and Quality Assurance in the Evolution of Fast Rotating Parts in High Temperature Environment Manufactured From TiAl

Intermetallic γ-titanium aluminides are a promising material in high temperature technologies. Their high specific strength at temperatures above 700°C offers the possibility for their use as components of aerospace and automotive industries. With a specific weight of 50% of that of the widely used Ni-based superalloys TiAl is very suitable as material for fast rotating parts like turbine blades in aircraft engines and land based power stations or turbocharger rotors. Thus lower mechanical stresses and a reduced fuel consumption and CO2-emission are expected. To overcome the insufficient oxidation protection the halogen effect offers an innovative way. After surface doping using F-implantation or liquid phase-treatment with an F-containing solution and subsequent oxidation at high temperatures the formation of a protective alumina scale can be achieved. By using non-destructive ion beam analyses (PIGE, RBS) F was found at the metal/oxide interface. For analysis of large scale components a new vacuum chamber at the IKF was installed and became operative. With this prototype of in-situ quality assurance system for the F-doping of manufactured parts from TiAl some performance test measurements were done and presented in this paper.Received: 01 March 2013; Revised: 24 April 2013; Accepted: 25 April 201

The measurement of long period and secular deformation with deep borehole tiltmeters

Two clusters of instruments were emplaced in fractured bedrock in eastern Massachusetts in 1970 and 1975. The intrasite agreement at tidal periods was about two percent, but there is no agreement at longer periods. A strong temperature-induced annual component ranging from 3 to 15 urads was present on instruments installed at depths of 15-20m; it was not apparent on those at 100-120m. One instrument, in continuous operation for three years at 100m, showed a net drift of 0.3 urads down to the SW, with a maximum departure of 2.0 urads from the trend. Pore pressure variations, material corrosion and creep, and local movements are apparently the limiting factors to long-term measurements

Development of a PIGE-Detection System for in-situ Inspection and Quality Assurance in the Evolution of Fast Rotating Parts in High Temperature Environment Manufactured from TiAl

Intermetallic γ-titanium aluminides are a promising material in high temperature technologies. Their high specific strength at temperatures above 700°C offers the possibility for their use as components of aerospace and automotive industries. With a specific weight of 50% of that of the widely used Ni-based superalloys TiAl is very suitable as material for fast rotating parts like turbine blades in aircraft engines and land based power stations or turbocharger rotors. Thus lower mechanical stresses and a reduced fuel consumption and CO2-emission are expected. To overcome the insufficient oxidation protection the halogen effect offers an innovative way. After surface doping using F-implantation or liquid phase-treatment with an F-containing solution and subsequent oxidation at high temperatures the formation of a protective alumina scale can be achieved. By using non-destructive ion beam analyses (PIGE, RBS) F was found at the metal/oxide interface. For analysis of large scale components a new vacuum chamber at the IKF was installed and became operative. With this prototype of in-situ quality assurance system for the F-doping of manufactured parts from TiAl some performance test measurements were done and presented in this paper.Received: 01 March 2013; Revised: 24 April 2013; Accepted: 25 April 201

ANALYSIS OF THE ELECTRICAL CHARACTERISTICS IN MULTIPHASE FLOW THROUGH THE WIRE-MESH SENSOR

Many studies on the characterization of electrical properties of multiphase fluid are found in the literature. One of the main motivations of these efforts has been the development of instrumentation for the measurement of volumetric fraction using electrical sensors. Although one can find a variety of instruments for that purpose, relatively few works in the open literature present studies on the best range of measurement frequency and its effect on permittivity models. An experimental and theoretical study is presented, where the best frequency to measure the volumetric fraction in two and three-phase mixtures is selected. Several permittivity models are applied to measure the volumetric fraction. The fluids used in the experiments were tap water, deionized water, mineral oil, isopropyl alcohol and hexane. Known volumes of fluids were mixed until obtaining a homogeneous mixture. The data were taken by a 1×4 wire-mesh sensor (WMS) immersed in the mixture. The WMS had a gap between planes of 1.4 mm, the wires were 3 mm apart from each other and the diameter of the wires was of 0.2 mm. The experimental system consisted of a generator, an oscilloscope and conditioning circuits (formed by operational amplifiers). A frequency scan was performed between 7000 Hz and 20 MHz for each mixture. A total of 60 logarithmically spaced frequencies were applied

Tidal friction in the solid earth

The earth's imperfectly elastic response to body and loading tidal forces is discussed using complex Love numbers and complex mass loading coefficients. Exact analytical expressions were derived relating the energy dissipation within an inhomogeneous, compressible solid earth to the surface values of these complex characteristic numbers, thus relating the global dissipation function Q to the phase shifts in the potential, gravity, tilt, strain and displacement tides. Integration of a global ocean tidal model shows that energy dissipated in the solid earth due to ocean loading is at least 10% of that dissipated in the body tides

On the stress dependence of the earthquake b value

Laboratory experiments have shown that the b value in the size distribution of acoustic emission events decreases linearly with differential stress. There have been a number of observations that indicate that this relation may also hold for earthquakes. Here using a simple frictional strength model for stresses in the continental lithosphere combined with earthquake b values measured as a function of depth in a wide variety of tectonic regions, we verify and calibrate that relation, finding b = 1.23 ± 0.06 − (0.0012 ± 0.0003)(σ1 − σ3), where the stress difference (σ1 − σ3) is in megapascal. For subduction zones, we find that b value correlates linearly with the slab pull force and with the net reduction of plate interface normal force, both of which also indicate a negative linear relation between b value and differential stress

Effects of Surface Geology on Seismic Ground Motion Deduced from Ambient-Noise Measurements in the Town of Avellino, Irpinia Region (Italy)

The effects of surface geology on ground motion provide an important tool in seismic hazard studies. It is well known that the presence of soft sediments can cause amplification of the ground motion at the surface, particularly when there is a sharp impedance contrast at shallow depth. The town of Avellino is located in an area characterised by high seismicity in Italy, about 30 km from the epicentre of the 23 November 1980, Irpinia earthquake (M = 6.9). No earthquake recordings are available in the area. The local geology is characterised by strong heterogeneity, with impedance contrasts at depth. We present the results from seismic noise measurements carried out in the urban area of Avellino to evaluate the effects of local geology on the seismic ground motion. We computed the horizontal-to-vertical (H/V) noise spectral ratios at 16 selected sites in this urban area for which drilling data are available within the first 40 m of depth. A Rayleigh wave inversion technique using the peak frequencies of the noise H/V spectral ratios is then presented for estimating Vs models, assuming that the thicknesses of the shallow soil layers are known. The results show a good correspondence between experimental and theoretical peak frequencies, which are interpreted in terms of sediment resonance. For one site, which is characterised by a broad peak in the horizontal-to-vertical spectral-ratio curve, simple one-dimensional modelling is not representative of the resonance effects. Consistent variations in peak amplitudes are seen among the sites. A site classification based on shear-wave velocity characteristics, in terms of Vs30, cannot explain these data. The differences observed are better correlated to the impedance contrast between the sediments and basement. A more detailed investigation of the physical parameters of the subsoil structure, together with earthquake data, are desirable for future research, to confirm these data in terms of site response

Лазерное инициирование порошков тэна в условиях объемного сжатия

Определены энергетические пороги инициирования и исследована кинетика процесса взрывного разложения порошков тетранитрата пентаэритрита, объемносжатых до давления 5·108Н/м2, при воздействии импульсом лазерного излучения на длинах волн 1064 нм (область прозрачности) и 266 нм (область собственного поглощения). Реализованы условия низкопорогового инициирования для порошков чистого тэна первой, второй и четвертой гармониках излучения неодимового лазера

Reply to 'A Second Opinion on "Operational Earthquake Forecasting: Some Thoughts on Why and How," by Thomas H. Jordan and Lucile M. Jones,' by Stuart Crampin

In folklore, a "silver bullet" is an effective weapon against were-wolves and witches. In earthquake prediction, a silver bullet is a diagnostic precursor—a signal observed before an earthquake that indicates with high probability the location, time, and magnitude of the impending event (Jordan 2006). In his comment, Crampin (2010) claims that shear-wave splitting (SWS) observations provide a silver bullet. He asserts that seismology is thus capable of raising earthquake forecasting out of the low-probability environment to which we assigned it in our recent opinion piece (Jordan and Jones 2010)