A model metal potential exhibiting polytetrahedral clusters

Putative global minima have been located for clusters interacting with an aluminium glue potential for N<190. Virtually all the clusters have polytetrahedral structures, which for larger sizes involve an ordered array of disclinations that are similar to those in the Z, H and sigma Frank-Kasper phases. Comparisons of sequences of larger clusters suggest that the majority of the global minima will adopt the bulk face-centred-cubic structure beyond N=500.Comment: 14 pages, 7 figure

A continuum mechanic design aid for non-planar compliant mechanisms

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2002.Includes bibliographical references (p. 151-152).This thesis documents the development of CoMeT, a conceptual evaluation and detailed synthesis aid for the design of compliant mechanisms. The vision behind CoMeT is making the limiting step in flexure design the speed of the user's imagination, not proficiency with software tools. Sophisticated kinematic analysis routines are seamlessly integrated into a three dimensional finite element program. A user may interface through both a convenient GUI and the powerful MATLAB command line. CoMeT's element models have been shown to generally lie within 3% of traditional FEA predictions. The experimentally determined response of a typical complex mechanism differed by less than 10%, and CoMeT proved to be just as accurate as conventional FEA. In a brief user interaction study, a subject with one hour of CoMeT training was able to perform a two-variable optimization in half the time it took with traditional software. Observations suggest that CoMeT encourages the conceptual thought and high-level insights that are the key to success in mechanism design.by Patrick Andreas Petri.S.M

Surfactants and enhanced oil recovery

This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University.A large number of commercial and some novel Brunel synthesised surfactants have been studied with a view to their potential usefulness for enhanced oil recovery (EOR) application. Ethoxylated phenols and their sulphonated derivatives were given especially high priority. The surfactants were well-characterised in order to understand their EOR potential. High pressure liquid chromatography, mass spectrometry, Raman spectrometry, nuclear magnetic resonance spectrometry and other quantitative techniques were used. Aspects of their behaviour (as single components and as blends with co-surfactants and co-solvents) which have been considered in terms of: (i) phase behaviour with brine and hydrocarbons (ii) adsorption onto various oxide surfaces (iii) interfacial properties such as surface tension, wetting, contact angles and viscosity (iv) stability Three different blends using sulphonated surfactants which: (i) produce a microeinulsion which is stable to high salinity brines over a large temperature range (ii) exhibit low adsorption onto reservoir rock (iii) interfacial tension as low as 10-2mNm-1 have been subsequently optimised. Core flooding tests carried out under reservoir conditions produced an additional 20% of the original-oil-in-place.Funded by Mobil North Sea Ltd

Obiter Dicta

"Stitched together over five years of journaling, Obiter Dicta is a commonplace book of freewheeling explorations representing the transcription of a dozen notebooks, since painstakingly reimagined for publication. Organized after Theodor Adorno’s Minima Moralia, this unschooled exercise in aesthetic thought—gleefully dilettantish, oftentimes dangerously close to the epigrammatic—interrogates an array of subject matter (although inescapably circling back to the curiously resemblant histories of Western visual art and instrumental music) through the lens of drive-by speculation. Erick Verran’s approach to philosophical inquiry follows the brute-force literary technique of Jacques Derrida to exhaustively favor the material grammar of a signifier over hand-me-down meaning, juxtaposing outer semblances with their buried systems and our etched-in-stone intuitions about color and illusion, shape and value, with lessons stolen from seemingly unrelatable disciplines. Interlarded with extracts of Ludwig Wittgenstein but also Wallace Stevens, Cormac McCarthy as well as Roland Barthes, this cache of incidental remarks eschews what’s granular for the biggest picture available, leaving below the hyper-specialized fields of academia for a bird’s-eye view of their crop circles. Obiter Dicta is an unapologetic experiment in intellectual dot-connecting that challenges much long-standing wisdom about everything from illuminated manuscripts to Minecraft and the evolution of European music with lyrical brevity; that is, before jumping to the next topic.

ADAPTIVE SAMPLING METHODS FOR TESTING AUTONOMOUS SYSTEMS

In this dissertation, I propose a software-in-the-loop testing architecture that uses adaptive sampling to generate test suites for intelligent systems based upon identifying transitions in high-level mission criteria. Simulation-based testing depends on the ability to intelligently create test-cases that reveal the greatest information about the performance of the system in the fewest number of runs. To this end, I focus on the discovery and analysis of performance boundaries. Locations in the testing space where a small change in the test configuration leads to large changes in the vehicle's behavior. These boundaries can be used to characterize the regions of stable performance and identify the critical factors that affect autonomous decision making software. By creating meta-models which predict the locations of these boundaries we can efficiently query the system and find informative test scenarios. These algorithms form the backbone of the Range Adversarial Planning Tool (RAPT): a software system used at naval testing facilities to identify the environmental triggers that will cause faults in the safety behavior of unmanned underwater vehicles (UUVs). This system was used to develop UUV field tests which were validated on a hardware platform at the Keyport Naval Testing Facility. The development of test cases from simulation to deployment in the field required new analytical tools. Tools that were capable of handling uncertainty in the vehicle's performance, and the ability to handle large datasets with high-dimensional outputs. This approach has also been applied to the generation of self-righting plans for unmanned ground vehicles (UGVs) using topological transition graphs. In order to create these graphs, I had to develop a set of manifold sampling and clustering algorithms which could identify paths through stable regions of the configuration space. Finally, I introduce an imitation learning approach for generating surrogate models of the target system's control policy. These surrogate agents can be used in place of the true autonomy to enable faster than real-time simulations. These novel tools for experimental design and behavioral modeling provide a new way of analyzing the performance of robotic and intelligent systems, and provide a designer with actionable feedback

Droplet Microfluidics

Droplet microfluidics has dramatically developed in the past decade and has been established as a microfluidic technology that can translate into commercial products. Its rapid development and adoption have relied not only on an efficient stabilizing system (oil and surfactant), but also on a library of modules that can manipulate droplets at a high-throughput. Droplet microfluidics is a vibrant field that keeps evolving, with advances that span technology development and applications. Recent examples include innovative methods to generate droplets, to perform single-cell encapsulation, magnetic extraction, or sorting at an even higher throughput. The trend consists of improving parameters such as robustness, throughput, or ease of use. These developments rely on a firm understanding of the physics and chemistry involved in hydrodynamic flow at a small scale. Finally, droplet microfluidics has played a pivotal role in biological applications, such as single-cell genomics or high-throughput microbial screening, and chemical applications. This Special Issue will showcase all aspects of the exciting field of droplet microfluidics, including, but not limited to, technology development, applications, and open-source systems

Existence Criteria of One-General Constraint Mechanisms

Mechanical Engineerin

A Geoconservation perspective on the trace fossil record associated with the end – Ordovician mass extinction and glaciation in the Welsh Basin

In this thesis I have illustrated the value of our geological heritage and geodiversity by focussing on a particular detailed aspect of the geological and palaeontological record, i.e. the trace fossil record associated with the end Ordovician (Hirnantian) global glaciation and extinction episode. The major elements of this work that are new are: • a significantly improved understanding of the nature of the soft sediment deformation, and in particular the role of “debrites” as basal landslide decollements in the Lower Palaozic Llangrannog rock succession of West Wales, • a much more detailed description of the trace fossil ichnocoenose present in the Llangrannog succession than has previously been published • an improved understanding of the nature of the ecological perturbation associated with the Hirnantian (Late Ordovician) Glacial “ice-house”, and the apparent role of an opportunistic soft body fauna in filling ecological niches vacated as a consequence of the associated extinction. • Considerable thought has been given to the question of how to value abiotic nature, and it is argued that the methods of conservation valuation associated with “Geosystem services” and in particular “Natural Capital” hold considerable potential for the Geoconservation community to engage with the public and with policy makers. • As a direct result of this research, two formal proposals have been put forward for new RIGS sites, together with a new geological SSSI