In the previous study, two Inside Temperature (IT dQ=0 and IT IM ) methods for estimating the temperature distributions in steady wave fronts in a thermoviscous material were established and the IT IM method was shown qualitatively to be effective for shock compressions where the effect of viscosity was distinguished. In this paper, these two methods are applied to the shock compressions of Yittria-doped Tetragonal Zirconia (YTZ) that is a thermoviscous material with a multiple shock Hugoniot. The YTZ Hugoniot consists of three partial curves including two kinks, that are the Hugoniot Elastic Limit (HEL) and the phase transition point. The shock temperatures evaluated by the IT IM method were close to the accurate temperatures obtained by the Walsh-Christian method in the whole stress range to 140 GPa examined here. Furthermore, the inside temperature distributions were approximately accurate because the effect of viscosity was distinguished in the shock compression. By these facts, it was considered that the fundamental assumption and the assumption on heat transport used in the IT IM method were valid and as a result, this method was effective. In addition, the influence of heat transport on the temperatures and thermoelastic stresses was examined.

One of the most crucial problems that the petroleum industry has been facing for quite some time, is the damage done to the sandstone formations by the produced water that is pumped into the ground during secondary oil recovery. The drastic reduction in permeability of these sandstone beds due to the water-shock, is a great concern in petroleum industry. The changes in produced water composition has made secondary oil recovery difficult. The decreasing permeability of the bed, increases the pumping and equipment cost to a great extent. The control of clay release is essential to the economic and effective operations in many oil fields. The main topic of this research is the effect of electrolytic composition in produced water on the clay particles pumped into sandstone formations or through sand-filters. Earlier studies [1–5] have revealed that high pH and low salt concentrations of water lead to release of clay from sand-grains. Also, there might be some clay particles injected into the ground with the produced water. These injected clays get captured by the sandstone bed. Both the release and capture of clays changes the porosity of bed and the surface area of sandstone particles and thus, reduces the permeability of the bed drastically. This paper just presents the experimental work done to predict the release of indigenous clay in the sand filter in aqueous phase flow. Future work will concentrate more on actual filtration experiments to release of indigenous clays and capture of injected clays in aqueous phase flow and the release-capture phenomena in two phase flows as well. In produced water operations, oil companies need to remove particles from the injection water to avoid formation damage. Consolidated Sand Cartridge filters are an inexpensive alternative compared to tradition means of filtering the particles. This work demonstrates the capability and advantages of these filters. The filter has properties similar to that of sandstone and so, results of clay migration study for the filter may be similar to sandstone bed as well. The Consolidated Sand filter is superior compared to conventional cylindrical sand filters in that its outer surface is expanded out into a six-lobe geometry with a larger surface area for filtration. Hence higher flow rates are achieved through the filter at a given pressure drop and the life of filter increases. Also, it has a glue bound sand structure which reduces the release of clay compared to the conventional sand filters. However, the disadvantage of the filter is that it is bulky and heavy and it adds to the disposal cost for the user. This work serves the dual purpose of characterizing the consolidated sand cartridge filter and also, studying the phenomena of clay release and capture in the sand filter to determine the optimum combination of pH and salt-concentration for minimal permeability loss. The phenomenon of clay release and capture is explained on basis of zeta potential of the particles, which characterize the surface charge of the particles.

Many protective devices, as well as spare and standby systems, exhibit what are known as non self-announcing failures; that is, failures can be observed only by inspection. Inspections can usually reveal only whether the device is operational or not, and not the level of deterioration of the device. This paper considers the availability of such systems when degradation is driven by an exogenous random environment. We allow this environment to be quite general; it includes both continuous (graceful) degradation and degradation due to discrete shocks. For periodic inspection schemes, we compute the limiting average availability and discuss opportunities for more effective inspection policies.

The temperature distributions in overdriven steady wave fronts in 2024 Al shocked up to 80 GPa were predicted using the thermoelastic theory (Wallace theory), where the viscous stress is neglected, and the thermoviscous theory (Sano-Abe theory). The Wallace theory was improved by applying a more exact equation to the bulk modulus. As shock loading was increased, the difference between the temperature distributions predicted using each theory was greater. This tendency of the difference was similar for shocks up to 250 GPa in Pt. Thus, temperature distributions in overdriven steady wave fronts cannot be effectively evaluated using thermoelastic theory.

The purpose of this study is to establish an Inside Temperature (IT) method for estimating temperatures in steady wave fronts in a thermoviscous material. A fundamental assumption that the material in the wave front, was approximately in an equilibrium state was used in this method. A further assumption that heat transport was neglected was used in the IT dQ=0 method, while in the IT IM method, the work done by the thermal stress was offset by heat transport. Two irreversible thermodynamic equations for the temperature in the wave front derived were connected with the Hugoniot function and the Mie-Grüneisen equation, respectively. To verify the efficacy of the IT method, three temperature distributions were estimated qualitatively using an equation for entropy including no assumption on heat transport, that including the assumption used in the IT dQ=0 method, and that in the IT IM method. These three distributions suggested that the temperatures were overestimated by the IT dQ=0 method, while the IT IM method was effective for shock compressions where the effect of viscosity was distinguished.

Dynamic instability induced by the initiation and development of mechanical faults in a rotary element is known to have a large negative impact on the reliability and operation safety of an entire system. This type of nonlinear system response is generally perturbed by shock impulses of extremely short time scale and amplitude. Thus difficulty presents itself in identifying and isolating features indicative of the presence and progression of faults possibly leading to mechanical deterioration. The perturbed and deteriorated states of a bearing-shaft system subjected to the actions of various types of commonly seen mechanical faults are investigated using the Numerical Hilbert Transform. The presented approach characterizes and realizes temporal events of both short and long time scales as instantaneous frequencies in the joint time-frequency domain. Examples are given to demonstrate the feasibility of applying the approach to the characterization of various deteriorating bearing states and the identification of parameters associated with several failure modes.

In order to accurately predict particle velocity profiles of steady shock wave fronts propagating in solid materials, a new numerical calculation method was proposed. The present method was based on one-dimensional Lagrangian finite difference wave code, and shock viscous stresses evaluated theoretically were introduced into the present numerical code. The shock viscous stress that is one of the important parameters to shape the rising profile of the shock wave front was calculated by the inside temperature estimate method for the steady shock wave fronts. The present calculation method was applied to the uniaxial strain problem of 6061-T6 aluminum at some stress levels below 8.86 GPa, where the elastic and plastic steady shock waves will appear. The results of the present calculation could reproduce more accurately the experimental data measured by the velocity interferometer system (VISAR). In addition, the present calculation was applied to a shock stress level of 20 GPa to investigate the shock viscous effects in the overdriven shock wave rising profile.

The paper presents the most recent developments on electronic bridge control applied to a bridge located along a southern Italian Motorway in an area where a landslip is in slow yet continuous motion. A previous bridge was closed for beam misalignment caused by the landslip action. A new bridge was recently designed with much sturdier foundations, but even during the initial construction phases it was evident that a static solution was undesirable, if not impossible. Jet, based on the observations of the last twenty years, the foreseen movements are relatively small, 20 cm being the maximum horizontal measured displacement in that period. A further version of the bridge has thus been proposed, characterised by lighter and longer decks, in order to negotiate the section with fewer elements. Moreover, the monitoring and repositioning systems have been thoroughly redesigned, to allow an almost continuous adjustment of the bridge decks, severely limiting the realignment times, in order to reduce traffic interruptions. A reduced number of interferometric lasers have been used, using rotating drums with mirrors individually preset to sweep the entire measuring field. The lifters, in their present version, should substitute the props, being used as active connections between pillars and decks, thus being able to support all traffic induced dynamic stresses in the vertical direction. The lifters have also been made sturdier eliminating all ball bearings in favour of teflon sheets. In addition, computer controlled lateral supports have been added to the system, allowing to move the deck horizontally while transmitting traffic or hearth-quake shocks to the pillars. On the top of each lifter an elastic interface bearing strain gauges will enable the measurement of tangential stresses as well as uneven distribution of the load, providing further information on the need of beams realignment.