The effect of the front-to-rear wheel torque distribution on vehicle handling: an experimental assessment

The front-to-rear wheel torque distribution influences vehicle handling and, ulti-mately, it affects key factors such as vehicle safety and performance. At a glance, due to part of the available tire-road friction being used for traction at the driven axle, a Front-Wheel-Drive (FWD) vehicle would be expected to be more understeering than a Rear-Wheel-Drive (RWD) vehicle. However, such effect may be counterbalanced, or even reversed, mainly due to the yaw moment caused by the lateral contribution of the traction forces at the front wheels. This paper proposes an experimental assessment, carried out on a fully electric vehicle with multiple mo-tors, allowing different front-to-rear wheel torque distributions. The results confirm that the yaw moment effect discussed is considerable, especially at low vehicle speeds and high steering an-gles. In particular, the RWD vehicle resulted more understeering than the FWD one at 30 km/h

Eliminating irreproducibility in SERS substrates

Irreproducibility in surface-enhanced Raman spectroscopy (SERS) due to variability among substrates is a source of recurrent debate within the field. It is regarded as a major hurdle towards the widespread adoption of SERS as a sensing platform. Most of the literature focused on developing substrates for various applications considers reproducibility of lower importance. Here, we address and analyse the sources of this irreproducibility in order to show how these can be minimised. We apply our findings to a simple substrate demonstrating reproducible SERS measurements with relative standard deviations well below 1% between different batches and days. Identifying the sources of irreproducibility and understanding how to reduce these can aid in the transition of SERS from the lab to real world applications.Isaac Newton Trust Leverhulme Trust Winton Programme for the Physics of Sustainability Trinity College, University of Cambridg

Vicinal Surfaces and the Calogero-Sutherland Model

A miscut (vicinal) crystal surface can be regarded as an array of meandering but non-crossing steps. Interactions between the steps are shown to induce a faceting transition of the surface between a homogeneous Luttinger liquid state and a low-temperature regime consisting of local step clusters in coexistence with ideal facets. This morphological transition is governed by a hitherto neglected critical line of the well-known Calogero-Sutherland model. Its exact solution yields expressions for measurable quantities that compare favorably with recent experiments on Si surfaces.Comment: 4 pages, revtex, 2 figures (.eps

Conformal Invariance in Percolation, Self-Avoiding Walks and Related Problems

Over the years, problems like percolation and self-avoiding walks have provided important testing grounds for our understanding of the nature of the critical state. I describe some very recent ideas, as well as some older ones, which cast light both on these problems themselves and on the quantum field theories to which they correspond. These ideas come from conformal field theory, Coulomb gas mappings, and stochastic Loewner evolution.Comment: Plenary talk given at TH-2002, Paris. 21 pages, 9 figure

Correlation decay and conformal anomaly in the two-dimensional random-bond Ising ferromagnet

The two-dimensional random-bond Ising model is numerically studied on long strips by transfer-matrix methods. It is shown that the rate of decay of correlations at criticality, as derived from averages of the two largest Lyapunov exponents plus conformal invariance arguments, differs from that obtained through direct evaluation of correlation functions. The latter is found to be, within error bars, the same as in pure systems. Our results confirm field-theoretical predictions. The conformal anomaly $c$ is calculated from the leading finite-width correction to the averaged free energy on strips. Estimates thus obtained are consistent with $c=1/2$, the same as for the pure Ising model.Comment: RevTeX 3, 11 pages +2 figures, uuencoded, IF/UFF preprin

Pulsed Molecular Optomechanics in Plasmonic Nanocavities: From Nonlinear Vibrational Instabilities to Bond-Breaking

Small numbers of surface-bound molecules are shown to behave as would be expected for opto-mechanical oscillators placed inside plasmonic nano-cavities that support extreme confinement of optical fields. Pulsed Raman scattering reveals superlinear Stokes emission above a threshold, arising from the stimulated vibrational pumping of molecular bonds under pulsed excitation shorter than the phonon decay time, and agreeing with pulsed optomechanical quantum theory. Reaching the parametric instability (equivalent to a phonon laser or ‘phaser’ regime) is however hindered by motion of gold atoms and molecular reconfiguration at phonon occupations approaching unity. We show how this irreversible bond breaking can ultimately limit the exploitation of molecules as quantum mechanical oscillators, but accesses optically-driven chemistry

Анализ влияния глобальных угроз на устойчивое развитие стран и регионов мира с помощью байесовских сетей доверия

Застосовано байєсівські мережі довіри для встановлення на якісному рівні причинно-наслідкових залежностей між глобальними загрозами і індексами сталого розвитку. Використання запропонованих в роботі методів синтезу мережі довіри та узагальнення результатів моделвання дозволило отримати цілісну інтерпетацію процесів впливу глобальних загроз на сталий розвиток країн і регіонів світу.Belief Bayesian Networks are used to establish the qualitative cause-effect relationships between global threats and indices of sustainable development. The method of belief network synthesis and the method of final results generalization were proposed. This made it possible to obtain a holistic understanding of effects of global threats to the sustainable development of countries and regions of the world

Role of charge patches in ion guiding through nanocapillaries in a PET polymer

We studied the dynamic properties of ion guiding through nanocapillaries in insulating polyethylene terephthalate (PET). The angular distribution of the transmitted ions was measured as a function of time. The temporal evolution of the angular transmission profiles was acquired for the capillary diameters of 200 and 400 nm. The tilt angle was varied from 0° to 6.5°. The transmission profiles exhibit significant changes in position as time varies. This observation is explained by the formation of temporary charge patches produced in the interior of the capillary besides the primary charge patch created in the entrance region.</p