2,372 research outputs found
Variation in the thickness of a fluid interface due to internal wave propagation:a lattice Boltzmann simulation
The change in the thickness of an interface between two immiscible fluids due to the propagation of an internal capillary-gravity wave along the interface is considered using a Bhatnagar, Gross and Krook (BGK) lattice Boltzmann model of a binary of fluid. The vertical thickness of the interface is recorded from the simulations since this is the most easily measured quantities in any simulation or experiment. The vertical thickness is then related to the actual thickness (perpendicular to the interface) which is seen to vary with the phase of the wave. The positions of the maxima and minimum thicknesses are seen to be approximately constant relative to the phase of the propagating wave and the range of variation of the thickness decreases at approximately the same rate as the wave amplitude is damped. A simplified model for the interface is considered which predicts a similar variation due to the interface being stretched as the internal wave propagates
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Development of a low-cost, electricity-generating Rankine cycle, alcohol-fuelled cooking stove for rural communities
This article describes a novel design and construction of a helical tube flash boiler that uses a 2kW nominal methylated spirit burner to heat an approximately 2.5m long coil of copper pipe fed by a nominal 8 bar electrically operated solenoid water pump. The final embodiment is for superheated steam to be converted to electricity and the waste exit heat from the generator used either for cooking or for ethanol pro duction for low-income families in developing countries. The performance of the flash boiler has been evaluated experimentally based on the well-known “Direct-Method”; by carefully measuring both the flow of the fuel and the steam. It found that the pressure inside the pipe can reach up to 7.4 bar and the temperature of the steam released by the flashing process can reach 255°C utilising a low-cost water pump. The research results prese nted in this paper demonstrate that flash boiler stove has a great potential for generating high-temperature steam for developing a low-cost cooking stove
Measuring the Intrarenal Distribution of Glomerular Volumes from Histological Sections.
M.S. Thesis. University of Hawaiʻi at Mānoa 2017
Integrated Numerical Modelling System for Extreme Wave Events at the Wave Hub Site
This paper examines an extreme wave event which occurred during a storm at the Wave Hub site in 2012. The extreme wave of 9.57 m height was identified from a time series of the heave data collected by an Oceanor Seawatch Mini II Buoy deployed at the site. An energy density spectrum was derived from this time series and then used to drive a physical model, which represents the extreme wave at 1:20 scale in Plymouth University’s new COAST Lab. The NewWave technique was used to define the input to the physical model. The experiment is reproduced in a numerical wave tank using the fully nonlinear CFD library OpenFOAM® and the wave generation toolbox waves2Foam. Results are evaluated, and issues regarding the predictions of a numerical model that is driven by the NewWave input signal are discussed. This study sets the basis for further research in coupling field data, physical modelling and numerical modelling in a more efficient and balanced way. This will lead to the new approach of composite modelling that will be implemented in future work
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The Influence of Heat Input Ratio on Electrical Power Output of a Dual-Core Travelling-Wave Thermoacoustic Engine
This paper presents an analytical and experimental investigation of an electricity generator that employs a two-stage looped tube travellin -wave thermoacoustic prime-mover to deliver acoustic power from heat energy, a loudspeaker to extract electricity from sound energy and a tuning stub to compensate the changes in the acoustic field within the engine to enable close to travelling wave operation at the loudspeaker. Furthermore, the paper explains how to enhance the output power utilizing different heat input ratios through the engine cores. A well-known thermoacoustic design tool called Delta EC is used to simulate the wave propagation through the different parts of the system. The electrical power predicted from the low-cost prototype was 24.4 W acoustic power which confirms the potential for developing low-cost thermoacoustic electricity generator for heat recov ery from low-grade heat sources. The electrical power can be increased to 31.3 W using different heating power percentages through the two units. The verified experimental data shows good agreement with DeltaEC results
Custodians of contemporary pluralism? Acas' evolving role in addressing conflict during a time of economic and regulatory flux
AbstractThis paper charts the development of Acas over the last two decades as it responds to the changing context of British employment relations. While dispute resolution services have evolved to focus on individual disputes, Acas has remained true to its pluralist roots through its training and advisory services that continue to promote ‘good employment relations’
Modelling and system identification of a stiff stay wire fence machine
This paper investigates a severe gear backlash problem encountered in a stiff stay machine that is capable of producing a 26 line fence up to 2.6 metres in height at a speed of 80 stays/minute. Related problems in the literature, typically concentrate on the effect of gear
backlash on the ability to control a shaft. However, in this case, very good control of the reference speed of the shaft was maintained in spite of the gear backlash. The problem was that the commanded torques were excessively large and threatened to damage the gear box.
This problem motivated a complete analysis of the systems dynamics including the development of a model to better understand the response and allow the identification of external loads on the system. It was found that the method of sensing the shaft position
(resolvers) was a major factor as well as the upgrading of the motor which was over responding to disturbances in the shaft. The model was validated using several torque
limiting experiments and gave accurate prediction of the machine’s major dynamics. The simulation tool developed provides the basis to predict the effect of different loads, wire types and/or motors on the machine for future designs minimizing the amount of experimentation on the machine
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Exploratory analysis using machine learning to predict for chest wall pain in patients with stage I non-small-cell lung cancer treated with stereotactic body radiation therapy.
Background and purposeChest wall toxicity is observed after stereotactic body radiation therapy (SBRT) for peripherally located lung tumors. We utilize machine learning algorithms to identify toxicity predictors to develop dose-volume constraints.Materials and methodsTwenty-five patient, tumor, and dosimetric features were recorded for 197 consecutive patients with Stage I NSCLC treated with SBRT, 11 of whom (5.6%) developed CTCAEv4 grade ≥2 chest wall pain. Decision tree modeling was used to determine chest wall syndrome (CWS) thresholds for individual features. Significant features were determined using independent multivariate methods. These methods incorporate out-of-bag estimation using Random forests (RF) and bootstrapping (100 iterations) using decision trees.ResultsUnivariate analysis identified rib dose to 1 cc < 4000 cGy (P = 0.01), chest wall dose to 30 cc < 1900 cGy (P = 0.035), rib Dmax < 5100 cGy (P = 0.05) and lung dose to 1000 cc < 70 cGy (P = 0.039) to be statistically significant thresholds for avoiding CWS. Subsequent multivariate analysis confirmed the importance of rib dose to 1 cc, chest wall dose to 30 cc, and rib Dmax. Using learning-curve experiments, the dataset proved to be self-consistent and provides a realistic model for CWS analysis.ConclusionsUsing machine learning algorithms in this first of its kind study, we identify robust features and cutoffs predictive for the rare clinical event of CWS. Additional data in planned subsequent multicenter studies will help increase the accuracy of multivariate analysis
"Royal wench" : investigating gender and power in the Antony and Cleopatra plays of the English Renaissance
In 1592, Mary Sidney Herbert, the Countess of Pembroke, published her dramatic version of the Antony and Cleopatra story, Antonius. In fairly quick succession, Samuel Daniel and Samuel Brandon published their own versions, The Tragedie of Cleopatra (1594) and The Tragicomeodi of the Vertuous Octavia (1598), of the ancient and tragic tale of love and politics. This study is an investigation into how these particular plays, using the same source story, illustrate the complex issues of gender and power in early modern England. In particular, I focus on how each writer's construction of the figures of Cleopatra and Antony illuminates how Renaissance cultural constructions of gender and power were made even more complex with the presence of Elizabeth I on the throne. Pembroke's Antonius seeks to subvert the cultural definitions of gender and power. Daniel uses his play to undermine the subversion of gender roles that Pembroke presents by returning to the figures of Antony and Cleopatra the traits with which they were invested in early modern culture. Brandon also resists the alternate reading of gender and power found in Antonius by presenting a positive vision of female power, Octavia, who reasserts the cultural definitions of gender and power. Brandon also explores more intensely the issues of power itself; that is, he moves from issues of gender and power to the issue of a ruler as a private and public person regardless of gender. My study also examines how changes in the power structure affect the use of the Antony and Cleopatra story. William Shakespeare's Anthony and Cleopatra (1606-1608) and Thomas May's The Tragedy of Cleopatra: Queen of Aegypt (1626), and John Dryden's All For Love (1678), all written after the death of Elizabeth I, reveal that the ancient source story continued to be a relevant text for political investigation regardless of the gender of the monarch. By examining the ways in which these plays interact with the cultural constructions of gender and power and how they interact with each other, this study illustrates the complex relationship of literature and culture as well as literature with literature
Diabetic Retinopathy Screening Using Computer Vision
6-pagesDiabetic Retinopathy (DR) is one of the main causes of blindness and visual impairment in
developed countries, stemming solely from diabetes mellitus. Current screening methods using fundus
images rely on the experience of the operator as they are manually examined. Automated methods based
on neural networks and other approaches have not provided sensitivity or specificity above 85%. This
work presents a computer vision based method that directly identifies hard exudates and dot
haemorrhages (DH) from 100 digital fundus images from a graded database of images using standard
computer vision techniques, and clinical observation and knowledge. Sensitivity and specificity in
diagnosis are 95-100% in both cases. Positive and negative prediction values (PPV, NPV) were 95-100%
for both cases. The overall method is general, computationally efficient and suitable for further clinical
trials to test both accuracy and the ability to the track DR status over time
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