Light Scattering by Cholesteric Skyrmions

We study the light scattering by localized quasi planar excitations of a Cholesteric Liquid Crystal known as spherulites. Due to the anisotropic optical properties of the medium and the peculiar shape of the excitations, we quantitatively evaluate the cross section of the axis-rotation of polarized light. Because of the complexity of the system under consideration, first we give a simplified, but analytical, description of the spherulite and we compare the Born approximation results in this setting with those obtained by resorting to a numerical exact solution. The effects of changing values of the driving external static electric (or magnetic) field is considered. Possible applications of the phenomenon are envisaged.Comment: 18 pages, 14 figure

Segmentation of the Visiting Friends and Relatives Travel Market

The visiting friends and relatives (VFR) travel market is a significant segment of the tourism industry, accounting for 76% of all trips to Illinois in 1991. This study determined the demographic, geographic, and psychographic characteristics and the benefits sought by those visiting friends and relatives in a Central Illinois Community. A self-administered questionnaire was sent to a systematic random sample of 660 inquirers to the local Convention and Visitors Bureau. Descriptive statistics were used to describe the following: (a) mode of transportation; (b) number of trips and length of stay; (c) demographic profile; (d) economic impact; and (e) impact of local university. The results of the study defined three VFR travel market segments, two of which closely resembled market segments profiled by Plog

An assessment of the effect of supersonic aircraft operations on the stratospheric ozone content

An assessment of the potential effect on stratospheric ozone of an advanced supersonic transport operations is presented. This assessment, which was undertaken because of NASA's desire for an up-to-date evaluation to guide programs for the development of supersonic technology and improved aircraft engine designs, uses the most recent chemical reaction rate data. From the results of the present assessment it would appear that realistic fleet sizes should not cause concern with regard to the depletion of the total ozone overburden. For example, the NOx emission of one type designed to cruise at 20 km altitude will cause the ozone overburden to increase by 0.03% to 0.12%, depending upon which vertical transport is used. These ozone changes can be compared with the predictions of a 1.74% ozone decrease (for 100 Large SST's flying at 20 km) made in 1974 by the FAA's Climatic Impact Assessment Program

Application of HTFC powered by LNG on a cruise ship: a case study

The 8th European Fuel Cell Technology & Applications Piero Lunghi Conference - EFC19, aims to bring together academia, research world, industry, public sector to exchange and share their experiences and research results on all aspects of Hydrogen and Fuel Cells technologies and clean energy. It also provides a premier interdisciplinary platform for researchers, practitioners and educators to present and discuss the most recent innovations, trends, and concerns as well as practical challenges encountered and solutions adopted in the fields of Hydrogen and Fuel Cells technologies and clean energy. EFC19 promotes the exchange of ideas on several topics, covering different areas, such as Transport, Infrastructures, Energy Storage, Energy Generation and Cross-cutting& Overarching. In particular, EFC19 covers research activities and studies on material development, manufacturing processes, modelling, diagnostics and process control, system engineering, market and deployment, demonstration and real-world experience. The Proceedings of the Conference collect 220 abstracts of papers presented during the Conference

Instalações.

Selecionando locais para as instalações. Instalações: abrigos, apriscos, baias para reprodutores, setor de manejo, sala de ordenha, quarentenario e ambulatório. Istalações para crescimento e engorda. Cercas para caprinos: convencionais e móveis. Equipamento para as instalações: comedouros, comedouros para concentrados, fenis, comedouros de concentrados e feno, comedouros conjugados as cercas, saleiro, manejo de dejetos

Non-linear Isolator for Vibration and Force Transmission Control of Unbalanced Rotating Machines

Purpose: The objective of this paper is to investigate with simulations how non-linear spring and non-linear damper components of isolators can be employed to effectively reduce both the oscillations and the force transmitted to ground in the whole spinning range of unbalanced rotating machines. Methods: The principal goal of this paper is twofold. First, to present a concise and consistent formulation based on the harmonic balance approach for the vibration response of spinning machines mounted on linear/non-linear, softening/hardening, un-tensioned/pre-tensioned springs and linear/non-linear dampers. Second, to provide a comprehensive overview of the vibration and force transmission control with non-linear isolators specifically tailored to unbalanced machines. Results: The study has shown that, the best vibration isolation is provided by a pre-tensioned linear and cubic softening spring combined with a linear and negative quadratic damper. The pre-tensioned spring should be designed in such a way as it holds the weight of the machine and thus produces on the vibrating machine a symmetric elastic restoring force proportional to the linear and cubic powers of the displacement. The cubic softening stiffness should then be tuned to minimise the frequency, and thus the amplitude, of the resonant response of the fundamental mode of the machine and elastic suspension system, while preserving stability and a desired static deflection. In parallel, to reduce the force transmission to ground above the fundamental resonance frequency, the negative quadratic damping effect should be tailored to maximize the energy absorption at higher frequencies. Conclusion: The study has shown that non-linear spring and non-linear damper components can be effectively employed to control the vibration and force transmission in the whole spinning range of the machine. In particular, a pre-tensioned softening cubic non-linear spring can be used to mitigate the vibration and force transmission at low frequencies, close to the fundamental natural frequencies of the elastically suspended machine. Also, a negative quadratic non-linear damper can be used to tailor the energy dissipation of the isolator in such a way as to have high damping at low frequencies and low damping at higher frequencies, which enhances the vibration and force transmission control at low frequencies and, rather importantly, mitigates the force transmission at higher frequencies