Detecting energy dependent neutron capture distributions in a liquid scintillator

A novel technique is being developed to estimate the effective dose of a neutron field based on the distribution of neutron captures in a scintillator. Using Monte Carlo techniques, a number of monoenergetic neutron source energies and locations were modelled and their neutron capture response was recorded. Using back propagation Artificial Neural Networks (ANN) the energy and incident direction of the neutron field was predicted from the distribution of neutron captures within a 6Li-loaded liquid scintillator. Using this proposed technique, the effective dose of 252Cf, 241AmBe and 241AmLi neutron fields was estimated to within 30% for four perpendicular angles in the horizontal plane. Initial theoretical investigations show that this technique holds some promise for real-time estimation of the effective dose of a neutron field

A novel approach to neutron dosimetry

Purpose: Having been overlooked for many years, research is now starting to take into account the directional distribution of neutron workplace fields. Existing neutron dosimetry instrumentation does not account for this directional distribution, resulting in conservative estimates of dose in neutron workplace fields (by around a factor of 2, although this is heavily dependent on the type of field). This conservatism could influence epidemiological studies on the health effects of radiation exposure. This paper reports on the development of an instrument which can estimate the effective dose of a neutron field, accounting for both the direction and the energy distribution. Methods: A 6Li-loaded scintillator was used to perform neutron assays at a number of locations in a 20 × 20 × 17.5 cm3 water phantom. The variation in thermal and fast neutron response to different energies and field directions was exploited. The modeled response of the instrument to various neutron fields was used to train an artificial neural network (ANN) to learn the effective dose and ambient dose equivalent of these fields. All experimental data published in this work were measured at the National Physical Laboratory (UK). Results: Experimental results were obtained for a number of radionuclide source based neutron fields to test the performance of the system. The results of experimental neutron assays at 25 locations in a water phantom were fed into the trained ANN. A correlation between neutron counting rates in the phantom and neutron fluence rates was experimentally found to provide dose rate estimates. A radionuclide source behind shadow cone was used to create a more complex field in terms of energy and direction. For all fields, the resulting estimates of effective dose rate were within 45% or better of their calculated values, regardless of energy distribution or direction for measurement times greater than 25 min. Conclusions: This work presents a novel, real-time, approach to workplace neutron dosimetry. It is believed that in the research presented in this paper, for the first time, a single instrument has been able to estimate effective dose

Organic Liquid Scintillators Based Source Localisation in Radiation Monitoring

No abstract available

Structural, magnetic, electrical, pseudocapacitive, and electrocatalytic properties of bilayered ruddlesden-popper oxides.

Ruddlesden Popper (RP) oxides are perovskite-derived functional materials with the general formula An-1Aʹ2BnO3n+1, where A/Aʹ is often a lanthanide or alkaline earth metal, and B is usually a transition metal. These materials contain perovskite-like connectivity, where BO6 units share apexes to form layers that are stacked above each other. The number of layers in each stack is represented by n in the above formula. The spaces between stacks are often occupied by lanthanide or alkaline-earth metals (Aʹ-site metals), which also reside in intra-stack spaces (A-site) between the octahedra. Oxide materials derived from perovskites have been studied for a wide range of applications, such as solar cells, batteries, catalysts, and capacitors. We have studied the electrocatalytic properties of RP materials for water splitting. This is an important application given the need for efficient and economical electrocatalysts for the two half-reactions of water-splitting, namely hydrogen-evolution reaction (HER) and oxygen-evolution reaction (OER). The benchmark catalysts to overcome the sluggish kinetics of OER and HER are Ru, Ir, and Pt-based catalysts. Such catalysts are expensive since they use precious metals, and some of them have stability issues. Owing to their compositional diversity and the thermodynamic stability, multi-element transition metal oxides are promising candidates for electrocatalytic water splitting. The variation of A and B-site metals in RP oxides can lead to changes in physical and chemical properties, such as crystal structure, magnetism, conductivity, and electrochemical catalysis. In this study, several bilayered (n = 2) RP oxides are synthesized followed by systematic study of magnetic, charge transport, pseudocapacitive, and electrocatalytic properties. The effect of structural symmetry on electrocatalytic properties in two isoelectronic materials, Sr2LaMn2O7 and Ca2LaMn2O7, which were synthesized by varying the A-site cation, was investigated. The structural changes identified are associated with systematic variation in the magnetic, electrical charge transport and electrocatalytic properties toward both components of water splitting, namely OER and HER. The effect of the B-site cation on electrocatalytic performance of two RP materials, Sr2LaFeMnO7 and Sr2LaCoMnO7 was also studied. Here, the variation in the B-site cation can result in significant changes in magnetic properties, charge-transport properties, and the activity toward the HER and OER processes. Together with the A/Aʹ and B-site changes of RP oxides, oxygen vacancies in these oxide materials strongly affect the properties including conductivity and electrocatalytic activity. Systematic trends in the series of materials, Sr3Ti2-xMxO7-δ (M = Mn, Fe, Co; x = 0, 1) were observed with the creation of oxygen vacancies which correlate with electrocatalytic and charge-transport properties. The bilayered RP materials have been also explored to understand the oxide intercalation based pseudocapacitance. The change in pseudocapacitive properties as a function of structural symmetry in two materials Ca2LaMn2O7 and Sr2LaMn2O7 was studied in the alkaline medium. Overall, in the bilayered RP oxides, the electrical, electrochemical and electrocatalytic characteristics can be modified by changing the elemental composition, symmetry, and oxygen vacancies

Access control, reverse access control and replication control in a world wide distributed system

In this paper we examine several access control problems that occur in an object-based distributed system that permits objects to be replicated on multiple machines. First, there is the classical access control problem, which relates to which users can execute which methods. Second, we identified a reverse access control problem, which concerns which replicas can execute which methods for authorized users. Finally, there is the issue of how updates are propagated securely from replica to replica. Our solution uses roles and preserves the scalability needed in a world-wide distributed system

Community Wellbeing Survey - Lane Cove

Lane Cove Council contracted UTS:CLG in 2014 to develop a community indicator framework to establish a set of indicators and measures of community wellbeing informed predominantly by the social issues aligned to Council’s Community Strategic Plan (CSP). The framework was built upon the objectives of the CSP and encompasses indicators and data sources that will increase Council’s awareness, knowledge and monitoring of current social issues and trends in Lane Cove

Big data analytics based short term electricity load forecasting model for residential buildings in smart grids

Electricity load forecasting has always been a significant part of the smart grid. It ensures sustainability and helps utilities to take cost-efficient measures for power system planning and operation. Conventional methods for load forecasting cannot handle huge data that has a nonlinear relationship with load power. Hence an integrated approach is needed that adopts a coordinating procedure between different modules of electricity load forecasting. We develop a novel electricity load forecasting architecture that integrates three modules, namely data selection, extraction, and classification into a single model. First, essential features are selected with the help of random forest and recursive feature elimination methods. This helps reduce feature redundancy and hence computational overhead for the next two modules. Second, dimensionality reduction is realized with the help of a t-stochastic neighbourhood embedding algorithm for the best feature extraction. Finally, the electricity load is forecasted with the help of a deep neural network (DNN). To improve the learning trend and computational efficiency, we employ a grid search algorithm for tuning the critical parameters of the DNN. Simulation results confirm that the proposed model achieves higher accuracy when compared to the standard DNN

Pacific Equatorial Age Transect : expeditions 320 and 321 of the riserless drilling platform from and to Honolulu, Hawaii (USA), Sites U1331–U1336, 5 March–4 May 2009 and Honolulu, Hawaii (USA), to San Diego, California (USA), Sites U1337–U1338, 4 May–22 June 2009

Integrated Ocean Drilling Program Expedition 320/321, "Pacific Equatorial Age Transect" (Sites U1331–U1338), was designed to recover a continuous Cenozoic record of the equatorial Pacific by coring above the paleoposition of the Equator at successive crustal ages on the Pacific plate. These sediments record the evolution of the equatorial climate system throughout the Cenozoic. As we gained more information about the past movement of plates and when in Earth's history "critical" climate events took place, it became possible to drill an age transect ("flow-line") along the position of the paleoequator in the Pacific, targeting important time slices where the sedimentary archive allows us to reconstruct past climatic and tectonic conditions. The Pacific Equatorial Age Transect (PEAT) program cored eight sites from the sediment surface to basement, with basalt aged between 53 and 18 Ma, covering the time period following maximum Cenozoic warmth, through initial major glaciations, to today. The PEAT program allows the reconstruction of extreme changes of the calcium carbonate compensation depth (CCD) across major geological boundaries during the last 53 m.y. A very shallow CCD during most of the Paleogene makes it difficult to obtain well-preserved carbonate sediments during these stratigraphic intervals, but Expedition 320 recovered a unique sedimentary biogenic sediment archive for time periods just after the Paleocene/Eocene boundary event, the Eocene cooling, the Eocene–Oligocene transition, the "one cold pole" Oligocene, the Oligocene–Miocene transition, and the middle Miocene cooling. Expedition 321, the second part of the PEAT program, recovered sediments from the time period roughly from 25 Ma forward, including sediments crossing the Oligocene/Miocene boundary and two major Neogene equatorial Pacific sediment sections. Together with older Deep Sea Drilling Project and Ocean Drilling Program drilling in the equatorial Pacific, we can delineate the position of the paleoequator and variations in sediment thickness from ~150°W to 110°W longitude