High Thermal Environment Research Articles

Distribution Law of High Temperature Mine's Thermal Environment Parameters and Study of Heat Damage's Causes

This essay begins with the accurate observation and analysis of the thermodynamic parameters such as temperature, pressure, wind speed, density, moisture content, relative humidity, enthalpy and humidity KaTa degree etc. And the relationship among these figures is pointed out. By the calculation of them we acquire the changing rules of Thermodynamic parameters and the distribution of Thermal source. According to that we can get the conclusion that the newly exposed rocks and the heat dissipation of fully mechanized coal mining face's surrounding rocks are mainly heat sources in coalmines. And it gives directions for governance of heat hazard in mines

Time relationships between volcanism–plutonism–alteration–mineralization in Cu-stratabound ore deposits from the Michilla mining district, northern Chile: a 40Ar/39Ar geochronological approach

The Michilla mining district comprises one of the most important stratabound and breccia-style copper deposits of the Coastal Cordillera of northern Chile, hosted by the Middle Jurassic volcanic rocks of the La Negra Formation. 40Ar/39Ar analyses carried out on igneous and alteration minerals from volcanic and plutonic rocks in the district allow a chronological sequence of several magmatic and alteration events of the district to be established. The first event was the extrusion of a thick lava series of the La Negra Formation, dated at 159.9 ± 1.0 Ma (2σ) from the upper part of the series. A contemporaneous intrusion is dated at 159.6 ± 1.1 Ma, and later intrusive events are dated at 145.5 ± 2.8 and 137.4 ± 1.1 Ma, respectively. Analyzed alteration minerals such as adularia, sericite, and actinolite apparently give valid 40Ar/39Ar plateau and miniplateau ages. They indicate the occurrence of several alteration events at ca. 160–163, 154–157, 143–148, and 135–137 Ma. The first alteration event, being partly contemporaneous with volcanic and plutonic rocks, was probably produced in a high thermal gradient environment. The later events may be related either to a regional low-grade hydrothermal alteration/metamorphism process or to plutonic intrusions. The Cu mineralization of the Michilla district is robustly bracketed between 163.6 ± 1.9 and 137.4 ± 1.1 Ma, corresponding to dating of actinolite coexisting with early-stage chalcocite and a postmineralization barren dyke, respectively. More precisely, the association of small intrusives (a dated stock from the Michilla district) with Cu mineralization in the region strongly suggests that the main Michilla ore deposit is related to a magmatic/hydrothermal event that occurred between 157.4 ± 3.6 and 163.5 ± 1.9 Ma, contemporaneous or shortly after the extrusion of the volcanic sequence. This age is in agreement with the Re–Os age of 159 ± 16 Ma obtained from the mineralization itself (Trista-Aguilera et al., Miner Depos, 41:99–105,2006).

新型転換炉「ふげん」用炉内中性子検出器の開発

In the Prototype Heavy Water Reactor "Fugen", Zircaloy-2 is used as in-core structural material for neutron economy. In-core neutron detectors for the Local Power Monitor are placed in heavy water moderator of 50°C. Such "Fugen" in-core conditions bring a high level thermal neutron flux environment, which burns away the neutron conversion material (235U) in the detector more rapidly compared to that of the light water reactors. Therefore, it was strongly required to realize a neutron detector which could work for a long time under such environment.To resolve this unexperienced subject, the authors started to develop an advanced in-core neutron detector for "Fugen" by adopting various technologies, The developed neutron detectors have smart structures and excellent characteristics such as (1) light weight structure to avoid gas displacement due to γ-heating, (2) structure of assembling detectors in a Zircaloy-2 tube, (3) wide range and linear current measuring performance and (4) long life performance by the use of mixed uranium (235U+234U). This kind of in-core neutron detector is now in the reactor core of "Fugen" nuclear power plant and is contributing to the high-efficient reactor operation.

On melting of the subducted oceanic crust: Effects of subduction induced mantle flow

Based on petrological and geochemical arguments, it is possible that arc magma is derived from subducted oceanic crust. In this paper, regional thermal models have been constructed to study the feasibility of melting cold subducted oceanic crusts at shallow depth (i.e. at depths of about 100 km) by a dynamic mantle. Calculated results suggest that plate subduction will generate an induced flow in the wedge above the subducting slab. This current continuously feeds hot mantle material into the corner and onto the slab surface. A high temperature thermal environment can be maintained in the vicinity of the wedge corner, immediately beneath the over-riding plate. Our regional models further demonstrate quantitatively that production of local melting is possible just about 30 km down dip from the asthenosphere wedge corner. Additional geological processes such as reasonable amounts of shear heating and minor dehydration (which will lower the local melting temperature) will further increase the probability of melting a cold subducted oceanic crust at shallow depth.

Physiological temperature response and embryonic mortality in stressed swine.

Physiological responses and some aspects of reproductive function were examined in mated female pigs subjected to a short-term heat stress during two intervals of early gestation. Trial 1 control and treated animals experienced temperatures of 24.0 and 40.2 degrees C, respectively, from days 2 through 13 of pregnancy. Trial 2 control and treated pigs were exposed to 23.3 and 40.4 degrees C, respectively, from days 14 through 25 of pregnancy. Both high thermal exposures caused significant increases (P less than 0.05) in rectal temperature. At body temperatures of 41.1 degrees C or above, animals became more active and behavioral patterns erratic. Stressed pigs in both trials exhibited adaptation to the short-term high thermal environment as treatment days progressed. Embryonic mortality in the stressed animals in trial 1 was greater than in controls, with the animals in the former group retaining a normal size litter or losing the entire litter by day of slaughter. A significant proportion (P less than 0.01) of litters from stressed animals contained degenerating fetuses at day 42 of gestation, suggesting a continuous or delayed effect of thermal stress on embryo survival.

Structural Ablative Plastics

Abstract Laminated reinforced plastics using carbon or silica fabrics and phenolic resins are widely used for ablative liners of rocket nozzles and for other applications requiring protection of structural elements in a high thermal environment. Under cyclic heating conditions, the phenolic resin chars, thereby providing ablation cooling; on cool-down, cracks and/or delaminations result in the majority of applications. On a reheat cycle, as in a multistart engine or other pulsed environment, a burn-through or other catastrophic failure may occur in the cracked areas.