Thermal history

Information about the times of thermal breakthrough and subsequent rates of thermal drawdown in enhanced geothermal systems (EGS) is necessary for reservoir management, designing fracture stimulation and well drilling programs, and forecasting economic return. Thermal breakthrough in heterogeneous porous media can be estimated using conservative tracers and assumptions about heat transfer rates; however, tracers that undergo temperature-dependent changes can provide more detailed information about the thermal profile along the flow path through the reservoir. To be effectively applied, the thermal reaction rates of such temperature sensitive traces must be well characterized for the range of conditions that exist in geothermal systems. Reactive tracers proposed in the literature include benzoic and

Effect of Mold Coating Materials and Thickness on Heat Transfer in Permanent Mold Casting of Aluminum Alloys A. HAMASAIID, MS DARGUSCH, CJ DAVIDSON, S. TOVAR, T. LOULOU, F. REZAI¨-ARIA, and G. DOUR ... These coatings maintain mechanical integrity and prevent ...

Annealing of the radiation damage generated in α-decay events is a common phenomenon in natural zircons. We have studied relationships between radiation damage, age and radionuclide content of natural zircons on a micro-scale. The degree of metamictisation was estimated by means of confocal laser–Raman spectroscopic measurements. Raman band broadening in well-ordered to moderately metamict zircons that have not experienced significant healing of the radiation damage since the time of their growth, shows a nearly linear dependence on the α-fluence. This dependence is proposed as a calibration line for examining unknown zircons in order to consider complete or incomplete damage storage, which may contribute to the understanding of the low-T thermal history of their host rocks. Seven examples for the application are presented. Radiation damage may anneal heterogeneously, with preferred re-ordering in more damaged micro-areas. Results suggest that single point defects do not anneal continuously over geologic periods of time but are, in contrast, a comparably stable type of radiation damage. In contrast to recrystallisation processes, structural recovery due to simple thermal annealing is not necessarily connected with loss of radiogenic Pb. The most prominent example for this are concordant zircons from Sri Lanka. Although they are excellent standards for U–Pb dating, Sri Lankan zircons should not be used as standards for structural radiation damage. The experimental work is completed by Monte Carlo simulations of α-decay events in zircon.

The Pinto shear zone is one of several Late Cretaceous shear zones within the eastern fringe of the Mesozoic magmatic arc of the southwest Cordilleran orogen that developed synchronous with continued plate convergence and backarc shortening. We demonstrate an extensional origin for the shear zone by describing the shear-zone geometry and kinematics, hanging wall deformation style, progressive changes in deformation

The increasing component packing density and consequent reduction in feature size in printed circuit assemblies (PCA's) continues to place manufacturers under extreme pressures. The most significant demand is for improved first-off process yields because of the high cost and technical difficulty of rework processes and concerns over the reliability of reworked products. The dominant process for the production of PCA's is reflow soldering of a stencil/screen printed solder paste to form the interconnection between the component termination and the substrate. It is crucial for the manufacturer to ensure that each termination experiences a suitable thermal history throughout the reflow cycle. Despite the advances in processes to cope with complex product features, such as increasing the uniformity and amount of heat transfer in the process, ensuring right-the-first-time is still a problem leading to increased lead-times, reduced yields and the scrapping of assemblies used to establish the ideal process parameters for each particular product. This paper describes the utilization of a predictive model as a tool for the off-line determination of the most appropriate process and its specific set-up for a PCA. Results are also presented where PCA design is altered to improve thermal mass distribution

The wealth of current knowledge on starch retrogradation is due in large measure to the wide array of analytical methods at the disposal of food scientists. Since retrogradation is a complex process affected by many factors, it is unlikely that any single method would be able to give a complete picture of the retrogradation properties of starch gels at both the macroscopic and molecular levels. Independent evidence derived from two or more methods allows cross comparisons that can provide a fuller understanding of this phenomenon. For quantitative measurement of rates of retrogradation, the “ideal” method should be simple, rapid, non-destructive, precise, and inexpensive. Comparisons of kinetic data from different sources should be made with caution; various factors (thermal history, in particular) that can lead to unjustifiable comparisons and erroneous conclusions should be carefully considered first. This review covers the general principles, capabilities, advantages, and limitations of various methods available to study starch retrogradation.

Apatite fission-track (FT) and (U–Th)/He analyses are used to constrain the low-temperature thermal history of the San Gabriel and San Bernardino Mountains (SGM and SBM), which are part of the southern California Transverse Ranges. FT ages from 33 SGM samples range from 3 to 64 Ma. Helium ages, ranging from 3 to 43 Ma, were obtained from 13 of these samples: all of the He ages are the same or younger than their respective FT ages. FT ages from 10 SBM samples were older, ranging from 45 to 90 Ma. The FT and ...

Carrageenophyte red seaweed from Oman, Hypnea bryoides, extracted using three different processes: an aqueous, a mild alkaline, and a more vigorous alkaline extraction was investigated. The resulting extract precipitated by alcohol was subject to chemical and rheological measurements. The total carbohydrate [ranged from 36.78 to 41.65 g/100 g], and ash [39.04 to 43.11 g/100 g] were the most abundant components in H. bryoides and contrary to the two, lipid content was found at a minimum [ranging from 2.95 to 3.38 g/100 g]. Alkali treatment with NaOH allowed complete conversion of kappa (κ) carrageenan form as detected by FTIR analysis. Total yield by alkali treatments gave higher yields (33%) compared with aqueous treatments (12%). However, subsequent aqueous treatment produced mixed carrageenan (μ and κ) with higher molecular weight compared with the alkali treatments which produced single carrageenan form (κ) with molecular weight of 4.1 × 10(5) Da. The effects of thermal history on gel-sol and sol-gel transition were investigated by differential scanning calorimeter (DSC) and rheology on a pure sample and 1.5% κ-carrageenan mixture added with 30 mM KCl. Transition temperatures from DSC and rheology showed comparable results and were in good agreement with those previously reported.

The 12th May 2008 Wenchuan earthquake in the Longmen Shan occurred on a large thrust fault largely inherited from an Indosinian structure itself probably controlled by an older structural heritage of the South China block continental margin. Within the whole northeast Tibet region, such a structural inheritance has had a major impact on the Tertiary deformation. It appears of primary importance to assess the pre-Tertiary tectonic evolution of the main blocks involved to understand the actual deformation in the eastern edge of Tibet ...

We review the current state of knowledge concerning microbial extremophiles and comets and the potential significance of comets to Astrobiology. We model the thermal history of a cometary body, regarded as an assemblage of boulders, dust, ices and organics, as it approaches a perihelion distance of ~ 1AU. The transfer of incident energy from sunlight into the interior leads to the melting of near surface ices, some under stable porous crust, providing possible habitats for a wide range of microorganisms. We provide data concerning new evidence for indigenous microfossils in CI meteorites, which may be the remains of extinct cometary cores. We discuss the dominant microbial communities of polar sea-ice, Antarctic ice sheet, and cryoconite environments as possible analogs for microbial ecosystems that may grow in sub-crustal pools or in ice/water films in comets.

Rheological properties of chocolate play a relevant role either in process design or texture definition. Nevertheless, only flow properties of molten product or mechanical properties of samples cooled at fixed temperature (usually 20 °C) are measured, whilst testing conditions close to the industrial applications (temperature close to 30 °C) are less common to be used. In this work, chocolate samples (cooled at 1 and 5 °C min−1) were characterised at 30 °C by using small-amplitude oscillations and low-stress creep tests, aiming at establishing how material properties are related to the chocolate microstructure. The effects of either 3 anhydrous milk fats (AMF), having different melting points, or sugar particle size were evaluated. It was found that addition of AMFs, owing to their solid content, can yield an increase in consistency; however, this effect is less relevant when coarse sugar is used, because of the broader particle size distribution, and it depends on the thermal history because of the different fat crystallisation time. Finally, creep tests resulted to be very sensitive in detecting changes in chocolate rheological properties.