The mid-ordovician oolitic ironstones of North Wales

Thesis submitted in partial fulfillment of the degree of Doctor of Philosophy of the Council for National Academic Awards (CNAA).Oolitic ironstones occur within the Lower Palaeozoic Welsh Basin as isolated deposits found over a wide geographical area. There are two phases of ironstone deposition, a minor Upper Arenig phase and a Mid-Ordovician (Upper Llanvirn to basal Caradoc) phase. Both correlate with eustatic falls of sea level which exposed the Irish Sea Landmass lying immediately to the northwest. This exposure resulted in deep chemical weathering and generation of lateritic soils. Erosion of this material formed the source for the oolitic' ironstones in the Welsh Basin. The ironstones formed above stratigraphic hiatuses on sediment starved shallow water shoals, formed by synsedimentary faulting. These shoals were the favourable sites for the formation of berthierine peloids, which formed the nuclei for ooids. Additionally, they were also the site for the accumulation of berthierine mud, which was closely linked with the development of ferruginous algal mats. Bacterial reduction of organic material associated with ironstones, supplied the necessary reducing conditions for the formation and preservation of berthierine from a kaolinite/iron oxide precursor. Ooids formed by rolling over the muddy surface and mechanically accreting berthierine. Subsequent tidal current reworking of this sediment resulted in the formation of the characteristic lithological features of the ironstones, representing a shallowing-up sequence. Progressive current winnowing led to the formation of a sequence with an upward increasing ooid content and decreasing mud content. The upper facies of the ironstones is an ooid bar deposit worked by tidal currents. Cessation of current reworking allowed faunal colonisation of the bar with significant bioturbation of the sediment, destroying primary sedimentary structures. The presence of some grain-ironstones indicate the original sedimentary state of the upper facies. Tectonic instability during deposition, by synsedimentary faulting, resulted in the formation of disturbed ironstones, and debris flows within the ironstone sequences. Many features of the ironstones are diagenetic in origin, especially the formation of phosphate nodules within the ironstone sequence. These formed just below the sediment/sea water interface, and some nodules were reworked into overlying beds. The source was phosphorus released from adsorption on clays and iron oxides, and also released from organic material. Later siderite development in the ironstones is indicated by the presence of primary cements in grain-ironstones and secondary alterations in pack-ironstones. The generation of diagenetic siderite was dependant upon the amount of organic material within the ironstones, bacterial reduction of which resulted in the formation of bicarbonate and ferrous ions. Sane ironstones were subsequently altered during the Caradoc phase of volcanic activity. The formation of magnetite and stilpnomelane within the ironstones were caused by metasanatic activity associated with dolerite sills and microgranite intrusions. Siderite alteration and base metal sulphides resulted fram late stage hydrothermal activity by some microgranites. Contact metarrorphism by granophyric intrusions led to the extensive replacement of the ironstones by pyrite. Regional metarrorphism resulted in the progressive change of berthierine to chamosite and increased lattice ordering of chamosite

For hospitalized dementia patients, do nonpharmacological interventions reduce agitation?

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Subtractive clustering Takagi-Sugeno position tracking for humans by low-cost inertial sensors and velocity classification

In this work, open-loop position tracking using low-cost inertial measurement units is aided by Takagi-Sugeno velocity classification using the subtractive clustering algorithm to help generate the fuzzy rule base. Using the grid search approach, a suitable window of classified velocity vectors was obtained and then integrated to generate trajectory segments. Using publicly available experimental data, the reconstruction accuracy of the method is compared against four competitive pedestrian tracking algorithms. The comparison on selected test data, has demonstrated more competitive relative and absolute trajectory error metrics. The proposed method in this paper is also verified on an independent experimental data set. Unlike the methods which use deep learning, the proposed method has shown to be transparent (fuzzy rule base). Lastly, a sensitivity analysis of the velocity classification models to perturbations from the training orientation at test time is investigated, to guide developers of such data-driven algorithms on the granularity required in an ensemble modelling approach. The accuracy and transparency of the approach may positively influence applications requiring low-cost inertial position tracking such as augmented reality headsets for emergency responders.Engineering and Physical Sciences Research Council (EPSRC): EP/S513623/1 BAE System

Indirect tuning of a complementary orientation filter using velocity data and a genetic algorithm

In this paper, the accuracy of inertial sensor orientation relative to the level frame is improved through optimal tuning of a complementary filter by a genetic algorithm. While constant filter gains have been used elsewhere, these may introduce errors under dynamic motions when gyroscopes should be trusted more than accelerometers. Optimal gains are prescribed by a Mamdani fuzzy rule base whose membership functions are found using a genetic algorithm and experimental data. Furthermore, model fitness is not based directly on orientation but the error between estimated and ground truth velocities. This paper has three interrelated novel elements. The main novelty is the indirect tuning method, which is simple, low-cost and requires a single camera and inertial sensor. The method is shown to increase tracking accuracy compared with popular baseline filters. Secondary novel elements are the bespoke genetic algorithm and the time agnostic velocity error metric. The contributions from this work can help improve the localization accuracy of assets and human personnel. This research has a direct impact in command and control by improving situational awareness and the ability to direct assets to safe locations using safer routes. This results in increasing safety in applications such as firefighting and battlespace.This research is funded by the Engineering and Physical Sciences Research Council (EPSRC) iCASE Grant reference EP/S513623/1 and BAE Systems

Increasing Use of Intermittent Auscultation for Low-Risk Laboring Women

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