Benzyl and platinum derivatives of organogermanes

The work described in this thesis is conveniently divided into three parts. PART A. Benzyl Derivatives of Germanium. Tetrabenzylgermane is cleaved by lithium in 1,2-dimethoxyethane to give moderate yields of tribenzylgermyl-lithium, but some dibenzyl-gerrnyl-dilithium is also produced. The germyl-lithium reagent does not attack the solvent at 0 , but at reflux temperature in the presence of an excess of lithium a progressive series of reactions takes place giving (PhCH(_2))(_3)GeMe, (PhCH(_2))(_2)GeMe(_2) and PhCH(_2)GeMe(_3). Many reactions of tribenzylgermyl-lithium are similar to those of other organolithium reagents. The reaction between tribenzylgermane and lithium is not selective. Both Ge-H and Ge-CH(_2)Ph bonds are cleaved, and this lack of selectivity is also shown by hexabenzyldigermane. Similar complications are evident in the reaction between butyl-lithium and tribenzylgermane. Both hydrogen-metal exchange to give (PhCH(_2))(_3)GeLi, and nucleophilic attack of Bu(^-) with displacement of either H(^-) or PhCH(_2)(^-) occurs. PART B. Triphenylgermylplatinum Complexes. Triphenylgermyl-lithium reacts with the complexes cis or trans (R(_3)P)(_2)PtCl(_2) [R = Et, n-Pr] to give (R(_3)P)(_2)Pt(GePh(_3))(_2). The iodide (R(_3)P)(_2)PtI(_2) reacts with triphenylgermyl-lithium partly by halogen-metal exchange, however, giving the lithio platinum derivatives (R(_3)P)(_2)Pt(Li) I and (R(_3)P)(_2)Pt(Li)GePh(_3). The complexes (R(_3)P)(_2) Pt(GePh(_3))(_2) are stable to air and water but decompose at 150 with cleavage of Ge-Pt, Ge-C and P-C bonds. Iodine, HCl, MeI, NgI(_2), C(_2)H(_4)Br(_2), PhLi and LiAlH(_4) all cleave both Ge-Pt bonds, and in some cases at least the reaction probably proceeds via platinum(IV) intermediates. Hydrogenolysis of one Ge-Pt bond takes place under extremely mild conditions, and this may also proceed via oxidation to a Pt(IV) complex. Stable alkoxy-platinum complexes, (R(_3)P)(_2)Pt(OR')GePh(_3), were produced by the action of alcohols on the intermediate (R(_3)P)(_2)Pt(I)GePh(_3). PART C. Infrared Spectra. Characteristic infrared frequencies are given for 90 organogermanes, including alkyls, aryls, hydrides, deuterides, halides and oxides, with the main object of assisting characterisation of similar compounds. Germanium-carbon stretching frequencies for trans and gauche forms of n-butylgermanes have been observed

Pattern Formation in a 2D Elastic Solid

We present a dynamical theory of a two-dimensional martensitic transition in an elastic solid, connecting a high-temperature phase which is nondegenerate and has triangular symmetry, and a low-temperature phase which is triply degenerate and has oblique symmetry. A global mode-based Galerkin method is employed to integrate the deterministic equation of motion, the latter of which is derived by the variational principle from a nonlinear, nonlocal Ginzburg-Landau theory which includes the sound-wave viscosity. Our results display (i) the phenomenon of surface nucleation, and (ii) the dynamical selection of a length scale of the resultant patterns.Comment: LaTeX, 14 pages with four post-script figures included by psfig. Three of these are colour, but viewable in black-and-white. Presented at the conference "Collective Phenomena in Physics: Pattern Formation in Fluids and Materials", University of Western Ontario, London, June 199

A report on the 6th European Conference on Structural Control

A short report is provided on the 6th European Conference on Structural Control which took place in Sheffield from 11–13 July 201

Robust methods for outlier detection and regression for SHM applications.

In this paper, robust statistical methods are presented for the data-based approach to structural health monitoring (SHM). The discussion initially focuses on the high level removal of the ‘masking effect’ of inclusive outliers. Multiple outliers commonly occur when novelty detection in the form of unsupervised learning is utilised as a means of damage diagnosis; then benign variations in the operating or environmental conditions of the structure must be handled very carefully, as it is possible that they can lead to false alarms. It is shown that recent developments in the field of robust regression can provide a means of exploring and visualising SHM data as a tool for exploring the different characteristics of outliers, and removing the effects of benign variations. The paper is not, in any sense, a survey; it is an overview and summary of recent work by the authors

On evolutionary system identification with applications to nonlinear benchmarks

This paper presents a record of the participation of the authors in a workshop on nonlinear system identification held in 2016. It provides a summary of a keynote lecture by one of the authors and also gives an account of how the authors developed identification strategies and methods for a number of benchmark nonlinear systems presented as challenges, before and during the workshop. It is argued here that more general frameworks are now emerging for nonlinear system identification, which are capable of addressing substantial ranges of problems. One of these frameworks is based on evolutionary optimisation (EO); it is a framework developed by the authors in previous papers and extended here. As one might expect from the ‘no-free-lunch’ theorem for optimisation, the methodology is not particularly sensitive to the particular (EO) algorithm used, and a number of different variants are presented in this paper, some used for the first time in system identification problems, which show equal capability. In fact, the EO approach advocated in this paper succeeded in finding the best solutions to two of the three benchmark problems which motivated the workshop. The paper provides considerable discussion on the approaches used and makes a number of suggestions regarding best practice; one of the major new opportunities identified here concerns the application of grey-box models which combine the insight of any prior physical-law based models (white box) with the power of machine learners with universal approximation properties (black box)

Experimental evaluation of environmental effects on a polymer-coated aluminium structure: a time-series analysis and pattern recognition approach

Temperature variation is an important issue that needs to be considered when trying to develop a reliable Structural Health Monitoring (SHM) strategy. In the case that a data-based approach is chosen for damage detection, environmental fluctuations could be erroneously regarded as an abnormal condition of the structure and could mask the presence of damage. One of the objectives of the current work is to examine a statistical pattern recognition approach for novelty detection under different temperature conditions. A second important issue that could hinder the reliability of a SHM strategy is any kind of nonlinear behaviour, not associated with damage, in a system. For the purposes of this paper, the dynamic behaviour of a polymer-coated aluminium structure with ribs fixed with bolts is examined. The autoregressive parameters are the damage sensitive features and later, it is performed Principal Component Analysis (PCA) for robust novelty detection that takes into account the temperature variation

Spent LWR fuel encapsulation and dry storage demonstration

In 1977 the Spent Fuel Handling and Packaging Program (SFHPP) was initiated by the Department of Energy to develop and test the capability to satisfactorily encapsulate typical spent fuel assemblies from commercial light-water nuclear power plants and to establish the suitability of one or more surface and near surface concepts for the interim dry storage of the encapsulated spent fuel assemblies. The E-MAD Facility at the Nevada Test Site, which is operated for the Department of Energy by the Advanced Energy Systems Division (AESD) of the Westinghouse Electric Corporation, was chosen as the location for this demonstration because of its extensive existing capabilities for handling highly radioactive components and because of the desirable site characteristics for the proposed storage concepts. This paper describes the remote operations related to the process steps of handling, encapsulating and subsequent dry storage of spent fuel in support of the Demonstration Program

Noise sensitivity of sub- and supercritically bifurcating patterns with group velocities close to the convective-absolute instability

The influence of small additive noise on structure formation near a forwards and near an inverted bifurcation as described by a cubic and quintic Ginzburg Landau amplitude equation, respectively, is studied numerically for group velocities in the vicinity of the convective-absolute instability where the deterministic front dynamics would empty the system.Comment: 16 pages, 7 Postscript figure

Critical exponents of directed percolation measured in spatiotemporal intermittency

A new experimental system showing a transition to spatiotemporal intermittency is presented. It consists of a ring of hundred oscillating ferrofluidic spikes. Four of five of the measured critical exponents of the system agree with those obtained from a theoretical model of directed percolation.Comment: 7 pages, 12 figures, submitted to PR

Resting-state functional connectivity and reading subskills in children

Individual differences in reading ability have been linked to characteristics of functional connectivity in the brain in both children and adults. However, many previous studies have used single or composite measures of reading, leading to difficulty characterizing the role of functional connectivity in discrete subskills of reading. The present study addresses this issue using resting-state fMRI to examine how resting-state functional connectivity (RSFC) related to individual differences in children\u27s reading subskills, including decoding, sight word reading, reading comprehension, and rapid automatized naming (RAN). Findings showed both positive and negative RSFC-behaviour relationships that diverged across different reading subskills. Positive relationships included increasing RSFC among left dorsal and anterior regions with increasing decoding proficiency, and increasing RSFC between the left thalamus and right fusiform gyrus with increasing sight word reading, RAN, and reading comprehension abilities. In contrast, negative relationships suggested greater functional segregation of attentional and reading networks with improved performance on RAN, decoding, and reading comprehension tasks. Importantly, the results suggest that although reading subskills rely to some extent on shared functional networks, there are also distinct functional connections supporting different components of reading ability in children