46 research outputs found

    Hera: evidence for multiple mineralization events and remobilization in a sediment-hosted Au-Pb-Zn-Ag deposit, Central New South Wales, Australia

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    The Hera Au-Ag-Pb-Zn deposit of central New South Wales, Australia with a total undepleted resource of 3.6 Mt @ 3.3 g/t Au, 25 g/t Ag, 2.6% Pb and 3.8% Zn occurs on the SE margin of the Cobar Basin. It is hosted by the shallow marine Mouramba Group and overlying turbiditic Amphitheatre Group. The siltstones comprise various mixtures of quartz, plagioclase, muscovite-phengite, biotite and clinochlore, along with accessory titanite and ilmenite. The deposit comprises a number of discrete lodes which are steeply west-dipping and strike NNW. Each lode has different abundances of the main ore minerals sphalerite, galena, chalcopyrite, pyrrhotite and electrum-gold. The North Pod and Far West lenses have the most diverse mineralogy in additionally containing arsenopyrite, native silver, gudmundite, Ag-tetrahedrite, acanthite, dyscrasite, native antimony, nisbite and breithauptite. Electrum (continuous spectrum from Ag-rich to Au-rich) is associated with sulfides in the main ore lenses while native gold occurs in the host rocks along cleavages/lineations and away from the main ore. The sulfur isotope data from across the deposit indicates a magmatic source. Most of the deposit has experienced greenschist facies metamorphism with pervasive green chlorite alteration, though the North Pod differs in being distinctly Ag- and Sb-rich and has reached at least amphibolite facies metamorphism with a garnet-wollastonite-vesuvianite-tremolite assemblage. Tremolite is relatively abundant throughout most of the deposit suggesting widespread low-T skarn alteration. Cross-cutting pegmatites comprise quartz, plagioclase (labradorite-andesine) and microcline. Hydrothermal remobilization is relatively extensive and best explains the unusual Ag-Sb-As assemblages of the North Pod and Far West lodes

    Intermittent conditioning of library archives: Microclimate analysis and energy impact

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    Libraries and archives house a majority of cultural heritage objects. The main purpose of libraries and archives is to provide suitable indoor climate conditions for preservation of their collection. In general, a large bulk of hygroscopic material is present which aids stable indoor climate conditions. Limited disturbances due to visitor presence occur in repositories and excludes to a large extent thermal comfort requirements. Library archives show potential of more tolerant setpoint control with permissible fluctuations. Little research is present into dynamic setpoint control and intermittent conditioning in libraries and archives. The aim of this study is to explore the possibility for intermittent conditioning and dynamic setpoint control on the energy impact and microclimate behavior in a library case study in The Netherlands. By means of a hygrothermal monitoring campaign from August 2016 to August 2017 the current indoor climate has been assessed under regular conditions and intervention periods (summer and winter) where the air handling unit was turned off. Both temporal and spatial measurements provided important information on microclimate behavior of the investigated repositories. A validated multi-zone model was used to investigate multiple setpoint strategies. Results show the potential of intermittent conditioning depending on whether dynamic setpoint conditions are used during operational hours (e.g. ASHRAE climate classes). If static conditions are applied, energy demand increases significantly, however, under dynamic setpoint control significant energy savings are possible. The lifetime multiplier is used to assess the chemical risks. The majority of investigated setpoint strategies show increased chemical risk

    Application of an integrated indoor climate, HVAC and showcase model for the indoor climate performance of a museum

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    This paper presents a case study on the performance based design of a HVAC system and controller of a museum. A famous museum in The Netherlands has reported possible damage to important preserved wallpaper fragments. The paper provides an evaluation of the current indoor climate by measurements, showing that the indoor climate performance does not satisfy the requirements for the preservation of old paper. To solve this problem we developed an integrated heat air and moisture (HAM) model consisting of models for respectively: the indoor climate, the HVAC system and controller and a showcase. The presented models are validated by a comparison of simulation and measurement results. The integrated model is used for the evaluation of a new HVAC controller design and the use of a showcase. It is concluded that it is not possible to satisfy the indoor climate within the recommended limits, exclusively by the use of a new control strategy. Furthermore in order to meet the recommendations, the wallpaper fragments should be placed in a showcase and a similar control strategy as presented in the paper, has to be implemented in order to limit the room air temperature change

    Energy efficient HVAC control in historical buildings: a case study for the Amsterdam Museum

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    Museums are often located in historical buildings. To provide suitable housing in a historical building for a museum, these buildings are usually adapted to suit the need for object preservation through HVAC control. Maintaining a strict indoor climate and limiting short fluctuations in indoor temperature and indoor relative humidity reduces risk on objects. However, this also results in a rather high energy demand and therefore rather high costs. Previous research showed the energy conservation possibilities for a museum with state-of-the-art building envelope by adapting setpoint strategies. A gap in literature is present in applying these strategies in historical museum buildings. The aim of this study is to make use of different setpoint strategies to provide an indication of possible energy conservation for a historical museum building with respect to object preservation and thermal comfort. The method used consists of a measurement campaign to establish the current indoor climate and a simulation study with different climate control strategies. The simulation study provides possibilities to assess energy efficient control strategies with preservation of valuable museum objects in mind. The Amsterdam Museum serves as a case study during this research. With the data obtained during the measurement campaign, a hygrothermal zone-simulation model was calibrated. The results of the different climate control strategies present the energy saving potential for historical museum buildings. It is concluded that using the adaptive thermal comfort guideline for temperature during opening hours, and letting the collection criteria developed by ASHRAE's climate classes determine the relative humidity during the day, can save up to approximately 15% for a historical museum building without increasing the risk to the collection

    Intermittent conditioning of library archives:Microclimate analysis and energy impact

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    \u3cp\u3eLibraries and archives house a majority of cultural heritage objects. The main purpose of libraries and archives is to provide suitable indoor climate conditions for preservation of their collection. In general, a large bulk of hygroscopic material is present which aids stable indoor climate conditions. Limited disturbances due to visitor presence occur in repositories and excludes to a large extent thermal comfort requirements. Library archives show potential of more tolerant setpoint control with permissible fluctuations. Little research is present into dynamic setpoint control and intermittent conditioning in libraries and archives. The aim of this study is to explore the possibility for intermittent conditioning and dynamic setpoint control on the energy impact and microclimate behavior in a library case study in The Netherlands. By means of a hygrothermal monitoring campaign from August 2016 to August 2017 the current indoor climate has been assessed under regular conditions and intervention periods (summer and winter) where the air handling unit was turned off. Both temporal and spatial measurements provided important information on microclimate behavior of the investigated repositories. A validated multi-zone model was used to investigate multiple setpoint strategies. Results show the potential of intermittent conditioning depending on whether dynamic setpoint conditions are used during operational hours (e.g. ASHRAE climate classes). If static conditions are applied, energy demand increases significantly, however, under dynamic setpoint control significant energy savings are possible. The lifetime multiplier is used to assess the chemical risks. The majority of investigated setpoint strategies show increased chemical risk.\u3c/p\u3
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