"The Given Force Cannot be a Function of Acceleration"

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Through-conjugation of two phosphaalkyne (‘CP’) moieties mediated by a bimetallic scaffold†

Through-conjugation of two phosphaalkyne moieties within an isolable molecule is demonstrated for the first time with the synthesis of [{Ru(dppe)2}2{μ-(CC)2C6H4-p}(CP)2], via base induced desilylation of [{Ru(dppe)2}2{μ-(CC)2C6H4 p}Cl2]. The nature of the cyaphide ligands and their influence upon the bimetallic core are studied electrochemically

An assessment of the strength of knots and splices used as eye terminations in a sailing environment

Research into knots, splices and other methods of forming an eye termination has been limited, despite the fact that they are essential and strongly affect the performance of a rope. The aim of this study was to carry out a comprehensive initial assessment of the breaking strength of eye terminations commonly used in a sailing environment, thereby providing direction for further work in the field. Supports for use in a regular tensile testing machine were specially developed to allow individual testing of each sample and a realistic spread of statistical data to be obtained. Over 180 break tests were carried out on four knots (the bowline, double bowline, figure-of-eight loop and perfection loop) and two splices (three-strand eye splice and braid-on-braid splice). The factors affecting their strength were investigated. A statistical approach to the analysis of the results was adopted. The type of knot was found to have a significant effect on the strength. This same effect was seen in both types of rope construction (three-strand and braid-on-braid). Conclusions were also drawn as to the effect of splice length, eye size, manufacturer and rope diameter on the breaking strength of splices. Areas of development and further investigation were identified

Artifacts at 4.5 and 8.0 um in Short Wavelength Spectra from the Infrared Space Observatory

Spectra from the Short Wavelength Spectrometer (SWS) on ISO exhibit artifacts at 4.5 and 8 um. These artifacts appear in spectra from a recent data release, OLP 10.0, as spurious broad emission features in the spectra of stars earlier than ~F0, such as alpha CMa. Comparison of absolutely calibrated spectra of standard stars to corresponding spectra from the SWS reveals that these artifacts result from an underestimation of the strength of the CO and SiO molecular bands in the spectra of sources used as calibrators by the SWS. Although OLP 10.0 was intended to be the final data release, these findings have led to an additional release addressing this issue, OLP 10.1, which corrects the artifacts.Comment: 14 pages, AASTex, including 5 figures. Accepted by ApJ Letter

Battery charger with a capacitor-diode clamped LLC resonant converter

The paper proposes a novel battery charger through use of two serially-connected LLC resonant converters. The first stage utilises a capacitor-diode clamped LLC resonant converter which allows operation in both constant voltage (CV) and constant current (CC) modes, as found in most battery chargers, to be realised, whilst the second stage provides the necessary gain and line and load regulation. A design example is included that demonstrates the resulting converter topology operating under the full battery charging conditions and its inherent current-limiting capability. Experimental results are used to validate the underlying approach

Minimum charge-recovery time control with parallel connected buck converters

Optimal-time control to minimise a converter’s recovery time has thus far been reported only for single power module converters. This paper adapts the optimal-time control problem and applies it to converters based on multiple power modules. Additionally, a novel minimum charge-recovery time control is also proposed for the multiple power module converter which produces a recovery time shorter than that in the optimal-time control. A 20 W converter is used to demonstrate the improved characteristics under primary regions of operation. Results show that the transient recovery time during a load step change is improved by 75% compared to traditional optimal time control

From treebank resources to LFG F-structures

We present two methods for automatically annotating treebank resources with functional structures. Both methods define systematic patterns of correspondence between partial PS configurations and functional structures. These are applied to PS rules extracted from treebanks, or directly to constraint set encodings of treebank PS trees

The Modelling and Analysis of the Mechanics of Ropes

This book considers the modelling and analysis of the many types of ropes, linear fibre assemblies. The construction of these structures is very diverse and in the work these are considered from the modelling point of view. As well as the conventional twisted structures, braid and plaited structures and parallel assemblies are modelled and analysed, first for their assembly and secondly for their mechanical behaviour. Also since the components are assemblies of components, fibres into yarns, into strands, and into ropes the hierarchical nature of the construction is considered. The focus of the modelling is essentially toward load extension behaviour but there is reference to bending of ropes, encompassed by the two extremes, no slip between the components and zero friction resistance to component slip. Friction in ropes is considered both between the rope components, sliding, sawing and scissoring, and within the components, dilation and distortion, these latter modes being used to model component set, the phenomenon instrumental in rope proofing. The exploitation of the modelling is closed by the suggested modelling and analysis of component wear and life limitation and also of rope steady state heating. These will require extensive experimentation to extract the necessary coefficients, achievable by parallel testing of prototypes and similar structures. This development is focused on the modelling and analysis of ropes and other similar structures. All the modelling is based on the Principle of Virtual Work and admissible modes of deformation. Finally this book is directed towards the various industries involved in design, manufacture and use of ropes, stays and other similar structures

Exploring Teacher Perceptions of the Leadership Practices of Middle and High School Principals

As educators continue to restructure schools to better meet the needs of our everchanging society, the principal’s effective leadership practices become paramount as we enter the next generation of research into school effectiveness. This study of principals in a large urban school district endeavors to examine the differences in middle and high school teachers’ perceptions of the leadership practices of educational leaders. The sample consisted of 242 participants from 12 middle schools and 404 participants from 14 high schools. Each of the participants were administered Kouzes and Posner’s Leadership Practices Inventory which identified the teachers perceptions of their principal’s leadership practices in each of five dimensions: (a) challenging the process, (b) inspiring a shared vision, (c) enabling others to act, (d) modeling the way, and (e) encouraging the heart. Middle and high school teachers reported very similar perceptions of their principals’ leadership practices. Additional analysis indicates that both middle and high school principals most often exhibited the practices of “enabling others to act” and “modeling the way” and least often demonstrated the behavior of “encouraging the heart.

Dynamics of Warm-Absorbing Gas in Seyfert Galaxies: NGC 5548

A hydromagnetic (MHD) wind from a clumpy molecular accretion disk is invoked to explain observations of warm absorbing (WA) gas in UVX from Sy galaxies. This paper focuses on two issues: (1) compatibility of kinematics and dynamics of MHD wind with the observed properties of WAs; and (2) relationship between the UVX absorptions. We provide an in-depth comparison between the MHD model and the Sy 1 galaxy NGC 5548, which at high spectral resolution exhibits a number of discrete UV absorption components. We find that: (1) the total column densities of Ovii, Oviii and H, are reproduced by constraining the UV ion column densities of Civ and Nv in each component to lie within a factor of 2 of their observed values and optimizing over the possible sets of component ionization states and Civ column densities; (2) the WA exists in the outer part of the wind and is not a continuation of the flow in the BLR; and (3) the WA extends in radial and polar directions and is ionization-stratified. X-ray absorption is found to be heavily biased towards smaller r, and UV absorption originates at larger distances from the central continuum source. We show that the discrete absorption components along the line-of-sight are intrinsically clumpy. Density differences between kinematic components result in a range of ionization and recombination timescales. We further test the applicability of the MHD wind to WAs in general, by constructing a quasi-continuous flow model, and extending it to arbitrary aspect angles. We estimate the fraction of Sy 1s having detectable WAs with larger Ovii column density than Oviii, and the range of total H column densities. We also find that the ratio of Ovii to Oviii optical depths can serve as a new diagnostic of AGN aspect angle.Comment: Latex, 8 postscript figures. Astrophysical Journal, 536, June 10, in pres