Direct dating of overprinting fluid systems in the Martabe epithermal gold deposit using highly retentive alunite

The Martabe deposits in Sumatra, Indonesia formed in a shallow crustal epithermal environment (200–350 °C) associated with mafic intrusions, usually recognised in domes, adjacent to an active right-lateral wrench system. Ten samples containing alunite were collected for high-resolution geochronology, to determine if overprinting fluid systems could be recognised by dating alunite separates. The heating time for each step was chosen to ensure reasonable uniformity in terms of the incremental percentage of 39Ar gas release during each of many steps, allowing age spectra to be analysed using the method of asymptotes and limits. Several distinct growth events could be recognised. In addition, each sample was subjected to ultra-high-vacuum (UHV) furnace step-heating, and 39Ar diffusion experiments conducted at the same time as 40Ar/39Ar geochronology, to determine the argon retentivity of the mineral grains being analysed. The heating schedule ensured Arrhenius data uniformly populated the inverse temperature axis, with sufficient detail to allow the application of the Fundamental Asymmetry Principle (FAP) during analysis of the Arrhenius spectrum. Results show activation energies between 370–660 kJ/mol. Application of Dodson’s recursion determines that closure temperatures would range from 400–560 °C for a cooling rate of 20 °C/Ma, which is higher than any possible temperature to be expected in the natural system. This gives confidence that the ages represent growth during periods of active fluid movement and alteration, since the deposit formed at temperatures < 200 °C at a depth of < 2 km. We conclude that gold in the Purnama pit was the result of fluid rock interactions during very short-lived mineral growth episodes at ~ 2.25 and ~2.00 Ma.

Which Strategy Saves the Most Energy for Stratified Water Heaters?

The operation of water heating uses a substantial amount of energy and is responsible for 30% of a household’s overall electricity consumption. Determining methods of reducing energy demand is crucial for countries such as South Africa, where energy supply is almost exclusively electrical, 88% of it is generated by coal, and energy deficits cause frequent blackouts. Decreasing the energy consumption of tanked water heaters can be achieved by reducing the standing losses and thermal energy of the hot water used. In this paper, we evaluate various energy-saving strategies that have commonly been used and determine which strategy is best. These strategies include optimising the heating schedule, lowering the set-point temperature, reducing the volume of hot water used, and installing additional thermal insulation. The results show that the best strategy was providing optimal control of the heating element, and savings of 16.3% were achieved. This study also determined that the magnitude of energy savings is heavily dependent on a household’s water usage intensity and seasonality.

Direct dating of overprinting fluid systems in the Martabe epithermal gold deposit using highly retentive alunite

The Martabe deposits in Sumatra, Indonesia formed in a shallow crustal epithermal environment (200–350 °C) associated with mafic intrusions, usually recognised in domes, adjacent to an active right-lateral wrench system. Ten samples containing alunite were collected for high-resolution 40Ar/39Ar geochronology, to determine if overprinting fluid systems could be recognised. At the same time, ultra-high-vacuum (UHV) furnace step-heating 39Ar diffusion experiments were conducted, to determine the argon retentivity of the mineral grains being analysed. The heating schedule chosen to ensure Arrhenius data uniformly populated the inverse temperature axis, with sufficient detail to allow the application of the Fundamental Asymmetry Principle (FAP) during data analysis. The heating time for each step was chosen to ensure reasonable uniformity in terms of incremental percentage gas release during each step. Results show activation energies between 360–500 kJ/mol, with normalised frequency factor between 1.89e14s−1 and 8.62e18s−1. Closure temperatures range from 390–519 °C for a cooling rates of 20 °C/Ma, giving confidence that the ages represent growth during periods of active fluid movement and alteration. The Martabe deposit formed at temperatures

The Effect of Heating Schedule on Physico-Chemical Properties of Instant Coffee of Liberika Tungkal Jambi

Abstract— The making of instant brewed coffee using co-crystallization method is strongly influenced by the heating schedule (HS) applied. Five levels of HS (HS1, HS2, HS3, HS4 and HS5) were studied on the physico-chemical properties of instant coffee of Liberika Tungkal Jambi. The treatment was applied in a completely randomized design with 4 replications. The coffee was extracted using a special coffee extractor in a ratio of hot water/coffee powder of 15/1. Parameters observed were moisture content, ash content, pH, solubility, and total dissolved solids. The data obtained were analyzed using ANOVA and DNMRT at 5% significance. The results showed that the physico-chemical properties of instant coffee had significant effect on moisture content, pH, solubility, and total dissolved solids but not on ash content. The optimal HS to produce Liberika Tungkal Jambi instant coffee with good quality was heating at 110oC in the beginning, followed by 90oC at the initiation of crystallization, and 75oC when crystal growth (HS3). HS3 produces instant coffee with water content 1.57-1.61%; ash content 6.12-6.16; pH 5.50-5.56; solubility 98.22-98.25; and total dissolved solids 8.47-8.53% Brix. Keywords— crystal growth,instant coffee, libtukom, recrystallization,

Using thermal transients at the outlet of electrical water heaters to recognise consumption patterns for heating schedule optimisation

In the midst of environmental concerns, and soaring energy costs and energy shortages, the efficiency of electrical household water heaters (EWHs) has been identified as an area with significant potential for savings. The benefits of applying optimised scheduling control for EWHs has been proven by various studies, however, little has been done to measure individual behaviour. This paper presents an alternative to the invasive and expensive solution of using water flow meters. A hardware and algorithmic solution is presented that uses thermal transients at the outlet of an EWH to measure consumption patterns. The results show that the approach is able to detect usage events with an accuracy of 91%. Despite the challenges related to thermal inaccuracies, event durations are estimated to within 2 minutes accuracy 79% of the time.