Wide area control of SVCs for first swing stabilisation and damping in longitudinal systems

A non-linear Kalman filter based control strategy for SVCs located in major load groups is presented. This focusses on the limitation and damping of inter-area modes. It does this through treating local modes as noise and uses a tunable nonlinear control algorithm to improve both first swing stability and system damping. Simulation on a four machine system shows that the Kalman filer can successfully lock on to a desired inter-area mode and obtain a 31% improvement in critical clearing time as well as improved damping.

Dragline swing automation

Draglines are used extensively for overburden stripping in Australian open cut coal mines. This paper outlines the design of a computer control system to implement an automated swing cycle on a production dragline. Subsystems and sensors have been developed to satisfy the constraints imposed by the task, the harsh operating environment and the mine's production requirements.

Swing load stabilization for mining and construction applications

This paper discusses the issue of sensing and control for stabilizing a swinging load. Our work has focused in particular on the dragline as used for overburden stripping in open-pit coal mining, but many of the principles would also be applicable to construction cranes. Results obtained from experimental work on a full-scale production dragline are presented.

Dragline swing automation

Draglines are very large machines that are used to remove overburden in open-cut coal mines. This paper outlines the design of a computer control system to implement an automated swing cycle on a production dragline. Subsystems and sensors have been developed to satisfy the constraints imposed by the task, the harsh operating environment and the mine's production requirements.

Case study: Dragline swing to dump automation

Dragline Swing to Dump Automation By Peter Corke, CSIRO Manufacturing Technology/CRC for Mining Technology and Equipment (CMTE) Peter Corke presented a case study of a project to automate the dragline swing to dump operation. The project is funded by ACARP, BHP Coal, Pacific Coal and the CMTE and is being carried out on a dragline at Pacific Coal's Meandu mine near Brisbane. Corke began by highlighting that the minerals industry makes extensive use of large, mechanised machines. However, unlike other industries, mining has not adopted automation and most machines are controlled by human operators on board the machine itself. Choosing an automation target The dragline automation was chosen because: ò draglines are one of the biggest capital assets in a mine; ò performance between operators vary significantly, so improved capital utilisation is possible; ò the dragline is often the bottleneck in production; ò a large part of the operation cycle is spent swinging from dig to dump; and ò it is technically feasible. There has been a history of drag line automation projects, none with great success.

Swing Low

From Kurt Vonnegut to Stephen King, many novelists use metanarrative techniques to insert fictional versions of themselves in the stories they tell. The function of deploying such techniques is often to draw attention to the liminal space between the fictional constructs inherent in the novel as a form, and the real world from which the constructs draw inspiration, and indeed, are read by an audience. For emerging writers working in short form narratives, however, the structural demands of the short story or flash fiction make the use of similar techniques problematic in the level of depth to which they can be deployed. ‘Swing Low’ is the fifth in a series of short stories that work to overcome the structural limitations of a succinct form by developing a fractured fictional version of the author over a number of pieces and published across a range of sites. The accumulative affect is a richer metanarrative textual arrangement that also allows for the individual short stories to function independently.

Swing amplification of nonaxisymmetric perturbations in stars and gas in a sheared galactic disk

We present a study of the growth of local, nonaxisymmetric perturbations in gravitationally coupled stars and gas in a differentially rotating galactic disk. The stars and gas are treated as two isothermal fluids of different velocity dispersions, with the stellar velocity dispersion being greater than that for the gas. We examine the physical effects of inclusion of a low-velocity dispersion component (gas) on the growth of non-axisymmetric perturbations in both stars and gas, as done for the axisymmetric case by Jog & Solomon. The amplified perturbations in stars and gas constitute trailing, material, spiral features which may be identified with the local spiral features seen in all spiral galaxies. The formulation of the two-fluid equations closely follows the one-fluid treatment by Goldreich & Lynden-Bell. The local, linearized perturbation equations in the sheared frame are solved to obtain the results for a temporary growth via swing amplification. The problem is formulated in terms of five dimensionless parameters-namely, the Q-factors for stars and gas, respectively; the gas mass fraction; the shearing rate in the galactic disk; and the length scale of perturbation. By using the observed values of these parameters, we obtain the amplifications and the pitch angles for features in stars and gas for dynamically distinct cases, as applicable for different regions of spiral galaxies. A real galaxy consisting of stars and gas may display growth of nonaxisymmetric perturbations even when it is stable against axisymmetric perturbations and/or when either fluid by itself is stable against non-axisymmetric perturbations. Due to its lower velocity dispersion, the gas exhibits a higher amplification than do the stars, and the amplified gas features are slightly more tightly wound than the stellar features. When the gas contribution is high, the stellar amplification and the range of pitch angles over which it can occur are both increased, due to the gravitational coupling between the two fluids. Thus, the two-fluid scheme can explain the origin of the broad spiral arms in the underlying old stellar populations of galaxies, as observed by Schweizer and Elmegreen & Elmegreen. The arms are predicted to be broader in gas-rich galaxies, as is indeed seen for example in M33. In the linear regime studied here, the arm contrast is shown to increase with radius in the inner Galaxy, in agreement with observations of external galaxies by Schweizer. These results follow directly due to the inclusion of gas in the problem.

Pillar height dependent formation of unprecedented Pd-8 molecular swing and Pd-6 molecular boat via multicomponent self-assembly

Three-component self-assembly of a cis-blocked 90 degrees Pd(II) acceptor with a mixture of a tetraimidazole and a linear dipyridyl donor self-discriminated into unusual Pd-8 molecular swing (1) and Pd-6 molecular boat (2), which are characterized by single-crystal X-ray diffraction analysis; their ability to bind C-60 in solution is established by fluorescence titration.

Determinación de la actividad radicular del Lima tahiti citrus aurantifolia (christm,) swing, mediante la variación de almacenamiento del agua del suelo, utilizando técnicas nucleares

Con el objetivo de determinar la actividad radicular y el patrón de distribución de las raíces activas del lima Tahití Citrus aurantifolia (Christm.) Swing., mediante la variación de almacenamiento de agua del suelo utilizando técnicas nucleares, se condujo un experimento en la finca San Bernardo, municipio de Masatepe, Departamento de Masaya. Se escogieron plantas de la misma edad, pureza varietal, características vegetativas uniformes y se establecieron en cada unidad experimental 4 tratamientos (50, 100, 150,200 cm de distancia del tronco), por 2 repeticiones para un total de 16 observaciones y se cubrió con plástico de polietileno negro en un área de 19.63 m2 que corresponde a un circulo de radio igual a 250 cm del tronco a cada árbol. En la época seca se tomaron lecturas, y la información obtenida y analizada permite concluir que en árboles de limón Tahití de 6 años de edad, y en las condiciones edafoclimáticas y de manejo del cultivo en que se llevó el experimento, presenta su actividad radicular directamente proporcional a las distancias horizontales del tronco del árbol, mediante el consumo total de agua en el volumen de suelo (O - 90 cm de profundidad), y a la vez directamente proporcional cada 30 cm de profundidad para un perfil de suelo de (O - 90 cm de profundidad), lo que indica presencia de un sistema radicular extenso y profundo.

Troca de cuidados: estudo sobre as negociações dos casais adeptos do swing acerca da prevenção de DSTs/AIDS.

A presente pesquisa tem como principal objetivo investigar as características do casal heterossexual moderno praticante de swing. Em especial, busca-se compreender quais fatores influenciam as negociações dos adeptos acerca da prevenção de DSTs/Aids. O swing, também conhecido como troca de casais, é considerado uma das experiências possíveis de não exclusividade sexual dentro da relação conjugal, o que significa dizer que os parceiros que o praticam, em comum acordo, permitem a ocorrência de intercursos sexuais envolvendo terceiros e preferencialmente em ambientes compartilhados. O estabelecimento do swing enquanto estilo de vida é a principal premissa dos praticantes. A partir das observações etnográficas de festas swingers realizadas em uma boate na Zona Oeste da cidade do Rio de Janeiro, da análise dos discursos de casais informantes e do levantamento das pesquisas sobre swing realizadas no Brasil, Europa e Estados Unidos, foi possível refletir a respeito das particularidades socioculturais deste grupo, bem como apreender o conjunto de valores que o orientam. As trajetórias dos sujeitos, desde o descobrimento do swing até o envolvimento real com o universo em questão, também são abordados neste trabalho. Finalmente, procura-se descrever e analisar os principais aspectos em torno das condutas sexuais dos swingers e a relação destas com o uso ou desuso de estratégias preventivas a fim de suscitar reflexões contributivas às discussões sobre prevenção de DSTs/Aids entre swingers.

A fully integrated 660 MHz low-swing energy-recycling DC-DC converter

A fully integrated 0.18 μm DC-DC buck converter using a low-swing "stacked driver" configuration is reported in this paper. A high switching frequency of 660 MHz reduces filter components to fit on chip, but this suffers from high switching losses. These losses are reduced using: 1) low-swing drivers; 2) supply stacking; and 3) introducing a charge transfer path to deliver excess charge from the positive metal-oxide semiconductor drive chain to the load, thereby recycling the charge. The working prototype circuit converts 2.2 to 0.75-1.0 V at 40-55 mA. Design and simulation of an improved circuit is also included that further improves the efficiency by enhancing the charge recycling path, providing automated zero voltage switching (ZVS) operation, and synchronizing the half-swing gating signals. © 2009 IEEE.

Experimental Study on the Subthreshold Swing of Silicon Nanowire Transistors

SOI based wrap-gate silicon nanowire FETs are fabricated through electron beam lithography and wet etching. Dry thermal oxidation is used to further reduce the patterned fins cross section and transfer them into nanowires. Silicon nanowire FETs with different nanowire widths varying from 60 nm to 200 nm are fabricated and the number of the nanowires contained in a channel is also varied. The on-current (I-ON) and off-current (I-OFF) of the fabricated silicon nanowire FET are 0.59 mu A and 0.19 nA respectively. The subthreshold swing (SS) and the drain induced barrier lowering are 580 mV/dec and 149 mVN respectively due to the 30 nm thick gate oxide and 1015 cm(-3) lightly doped silicon nanowire channel. The nanowire width dependence of SS is shown and attributed to the fact that the side-gate parts of a wrap gate play a more effectual role as the nanowires in a channel get narrower. It seems the nanowire number in a channel has no effect on SS because the side-gate parts fill in the space between two adjacent nanowires.