Study of the transmitter antenna gain for intersatellite laser communications

The gain of a transmitter for intersatellite communications is closely related to the performance of all the links. We calculate the transmitter telescope's gain with the help of the rigorous scalar diffraction theory and equivalent optical layout method. Furthermore, a comparison is performed with the conventional imaging method. The results show that the stop inside the telescope can affect the gain of the telescope. Finally, the gain is calculated under the condition of the aberrations. We find that different aberrations cause different effects. (C) 2006 Society of Photo-Optical Instrumentation Engineers.

Dammann SHG-FROG for characterization of the ultrashort optical pulses

In this paper we propose a very simple layout of multi-shot second-harmonic-generation (SHG) frequency-resolved optical gating (FROG) using three reflective Dammann gratings ( Dammann SHG-FROG) for characterization of the ultrashort optical pulses. One reflective Dammann gratings is used as the beamsplitter and the other two compensate the angular dispersion. Both theoretical and experimental results show that the distortions of the optical pulses introduced by the reflective Dammann gratings are very small. This device should be highly interesting for characterizing the ultrashort pulse. (C) 2005 Optical Society of America.

Study of the transmitter antenna gain for intersatellite laser communications

The gain of a transmitter for intersatellite communications is closely related to the performance of all the links. We calculate the transmitter telescope's gain with the help of the rigorous scalar diffraction theory and equivalent optical layout method. Furthermore, a comparison is performed with the conventional imaging method. The results show that the stop inside the telescope can affect the gain of the telescope. Finally, the gain is calculated under the condition of the aberrations. We find that different aberrations cause different effects. (C) 2006 Society of Photo-Optical Instrumentation Engineers.

一种高性能硅片曝光场分布优化算法

以提高光刻机应用性能为目的，提出了一种高性能硅片曝光场分布优化算法。由芯片尺寸计算得到最佳曝光场尺寸，使其最接近于光刻机提供的曝光场最大尺寸，提高了曝光系统的利用率；引入曝光场交错分布，减少了硅片边缘曝光场的交叠，提高了光刻产率；建立产率优先和良率优先两种优化方案，实现了产率和良率的共优。以实际芯片产品的参量为例，将本算法用于曝光过程，采用产率优先标准，曝光场数量减少了10％，而内场数量基本不变，提高了光刻的产率也确保了良率；采用良率优先标准，内场数量增长了10％，总的场数也有所减少，提高了光刻良率的可靠

Computational microscopy: turning megapixels into gigapixels

The layout of a typical optical microscope has remained effectively unchanged over the past century. Besides the widespread adoption of digital focal plane arrays, relatively few innovations have helped improve standard imaging with bright-field microscopes. This thesis presents a new microscope imaging method, termed Fourier ptychography, which uses an LED to provide variable sample illumination and post-processing algorithms to recover useful sample information. Examples include increasing the resolution of megapixel-scale images to one gigapixel, measuring quantitative phase, achieving oil-immersion quality resolution without an immersion medium, and recovering complex three dimensional sample structure.

A novel non-intrusive sampling technique for CO2 laser on-line beam monitoring utilising a silicon mirror

The measurement of high speed laser beam parameters during processing is a topic that has seen growing attention over the last few years as quality assurance places greater demand on the monitoring of the manufacturing process. The targets for any monitoring system is to be non-intrusive, low cost, simple to operate, high speed and capable of operation in process. A new ISO compliant system is presented based on the integration of an imaging plate and camera located behind a proprietary mirror sampling device. The general layout of the device is presented along with the thermal and optical performance of the sampling optic. Diagnostic performance of the system is compared with industry standard devices, demonstrating the high quality high speed data which has been generated using this system.

Comportamento Estrutural de Elementos em Aço Inoxidável

Atualmente, a utilização do aço inoxidável em elementos estruturais ainda é por muitos engenheiros e arquitetos, considerada uma solução extravagante para os problemas da engenharia. Todavia, mudanças de atitudes dentro da construção civil e uma transição global para um desenvolvimento sustentável e redução em impactos ambientais tem seguramente provocado um aumento no uso do aço inoxidável. A maioria das normas de projeto de aço inoxidável atuais ainda são baseadas em analogias assumidas com o comportamento de estruturas de aço carbono. Todavia, o aço inoxidável apresenta quatro curvas tensão versus deformação não-lineares sem patamar de escoamento e região de encruamento claramente definidos (tração e compressão, paralela e perpendicular a direção de laminação), modificando assim, seu o comportamento global. Na presente investigação foram utilizados o aço inoxidável austenítico 304, e o aço carbono USI 300, ambos com tensão de escoamento similares, mas com tensões últimas e ductilidades distintos. Em elementos estruturais submetidos a tensões normais de tração, usualmente a ruptura da seção líquida representa um dos estados limites últimos a serem verificados. Com o objetivo de se avaliar a resistência a tração de elementos estruturais aparafusados em aço inoxidável, este trabalho executou um programa experimental inovador envolvendo ligações aparafusadas defasadas sob tração. O programa experimental foi executado em peças de aço carbono e aço inoxidável de forma a comparar as principais semelhanças e diferenças entre estes dois tipos de aços estruturais. O programa experimental possibilitou que conclusões significativas no comportamento a tração destas ligações pudessem ser observadas. Dentre outras variáveis que controlam estes estados limites últimos foi verificada a influência significativa da espessura da placa de aplicação do carregamento, disposição, configuração e número de parafusos da ligação e propriedades do aço inoxidável como ductilidade e razão entre suas tensões de escoamento e de ruptura.

Perfil motivacional de las mujeres participantes en la prueba atlética de los 3000 metros obstáculos

[ES] Los 3000 metros obstáculos es una especialidad del atletismo ubicada dentro de las pruebas de medio fondo, que comprende la carrera plana y el paso de los obstáculos, incluyendo un foso agua llamado ría. Es la especialidad de atletismo con menos participantes en carrera ya sea en género femenino como en masculino, pero ¿A qué se debe esta baja participación? Tanto la alta exigencia técnica en carrera como los pasos de los obstáculos son una de las razones, ya que, el paso de la ría requiere una refinada técnica y dificultad adquirida. Este estudio analizará a distintas atletas, con el fin de crear el perfil motivacional de las atletas que compiten en esta prueba, encontrar las razones por las que se decantan por otras especialidades del atletismo y no por esta, y con ello averiguar las razones de la baja participación en esta modalidad.

Geotecnologias e recursos de multimídia no ensino de cartografia: percepção sócio ambiental do rio Alcântara no município de São Gonçalo/RJ

A disponibilidade gratuita na Internet de imagens de satélite e SIG somada à facilidade dos alunos no manuseio de multimídia através dos seus smartphones criam possibilidades para trabalhar com geotecnologias e recursos de multimídia no ensino de Cartografia. Nesta pesquisa foram avaliadas as contribuições, os limites e as possibilidades da inserção da tecnologia espacial, geoprocessamento e recursos de multimídia nas aulas de Geografia do sétimo ano da rede pública municipal de São Gonçalo/RJ; foi desenvolvida uma metodologia em meio digital, por meio da Internet, denominada Mapeando Meu Rio (MMR) cuja temática abordada foi a Percepção Socioambiental do Rio Alcântara. Observaram-se o interesse e o envolvimento dos alunos no decorrer das atividades propostas, por meio do uso de recursos de multimídia e geotecnologias como materiais de apoio à Educação Ambiental. Os resultados da avaliação do MMR mostraram que os alunos chegaram ao final do sétimo ano com dificuldades em relação à alfabetização cartográfica; isso foi constatado tanto na produção dos mapas mentais como também pela utilização do GPS, Google Earth e do ArcGIS Online. Os alunos tiveram dificuldades em utilizar os conhecimentos básicos da Cartografia para elaborar uma representação espacial, mais especificamente, legenda, coordenadas geográficas e orientação espacial. A alfabetização cartográfica não deve ser considerada como conteúdo que se restringe ao 6 ano, mas uma linguagem de comunicação para o entendimento da dinâmica espacial no decorrer do Ensino Fundamental e do Ensino Médio. As atividades geográficas deve permitir ao aluno melhorar a compreensão do espaço geográfico de uma maneira mais significativa para construir abstrações a partir da própria realidade, ou seja, do espaço vivido.

Report on proposed improvements to Teignmouth Harbour

This is the Report on Proposed Improvements to Teignmouth Harbour from 15th March, 1971 prepared for the Teignmouth Harbour Commission. It reviews the Scheme III Breakwater along the lines recommended by the Hydraulics Research Station and the implications of deepening the berths at the Eastern Quay to a depth of thirteen feet below chart datum. The layout of the Hydraulics Research Scheme III Breakwater, as described in Para.16 of their Report No. EX489 dated April 1970, is shown on the accompanying Key Plan to a scale of 1:2500. It contains a subsoil survey and boreholes structure. It goes through the permissible draughts of ships and turning area, training wall, deepening of the eastern quay dredging and sewage dispersal.

A CMOS analogue predistortion circuit for wideband optical fibre links

The laser is a major source of nonlinearity for optical fibre communication systems. In this paper, we propose a CMOS analogue predistortion circuit to reduce laser nonlinearity for wideband optical fibre links. The circuit uses a nonlinearity having the inverse transfer characteristic of the directly modulated vertical cavity surface emitting laser (VCSEL). It is shown by post-layout simulation that the predistortion circuit shows 12dBm improvement in the optical fibre system. The optical fibre transmitter front-end with predistortion lineariser is being fabricated using the austriamicrosystems (AMS) 0.3 5μm CMOS technology.

An experimental semi-active anti-roll system

The use of anti-roll bars to provide additional roll stiffness and therefore to reduce the trade-off between ride and rollover performance has previously been studied. However, little work has been carried out to investigate the benefits of a switchable roll stiffness. Such a semi-active anti-roll system has the ability to have a low roll stiffness during straight-ahead driving for improved ride performance and high roll stiffness during cornering for improved roll performance. Modelling of such a system is conducted and the model is validated against a semi-active anti-roll system fitted to an experimental vehicle. Experimental and theoretical investigations are used to investigate the performance of such a system with several different strategies employed to switch to the high-stiffness state. The use of an air suspension on the vehicle to roll into corners is also investigated, as is the possibility of exploiting the road layout by allowing the vehicle to be in a low-roll-stiffness configuration during a corner, and then to switch to the high-roll-stiffness configuration midcorner, hence 'locking in' a roll angle. The best rollover performance improvement that was achieved was 12.5 per cent. © IMechE 2008.

Segmentation and recognition using structure from motion point clouds

We propose an algorithm for semantic segmentation based on 3D point clouds derived from ego-motion. We motivate five simple cues designed to model specific patterns of motion and 3D world structure that vary with object category. We introduce features that project the 3D cues back to the 2D image plane while modeling spatial layout and context. A randomized decision forest combines many such features to achieve a coherent 2D segmentation and recognize the object categories present. Our main contribution is to show how semantic segmentation is possible based solely on motion-derived 3D world structure. Our method works well on sparse, noisy point clouds, and unlike existing approaches, does not need appearance-based descriptors. Experiments were performed on a challenging new video database containing sequences filmed from a moving car in daylight and at dusk. The results confirm that indeed, accurate segmentation and recognition are possible using only motion and 3D world structure. Further, we show that the motion-derived information complements an existing state-of-the-art appearance-based method, improving both qualitative and quantitative performance. © 2008 Springer Berlin Heidelberg.

A pilot plant for fish protein concentrate

This communication deals with the design aspect and functions of individual pieces of equipment of a pilot plant of fifty kg capacity for the production of fish protein concentrate (FPC) per day. Design is based on a solvent extraction process of wet pressed cake with an azeotropic mixture of hexane and ethyl alcohol. A flow sheet for the process and equipment layout has been indicated.

Pilot plant for production of fish ensilage and the economics of production

This communication describes the design aspect and functions of individual pieces of equipment of a pilot plant for the production of fish ensilage based on lactic acid fermentation process. Details about the equipment, process flow sheet and equipment layout of the pilot plant have been given. An attempt has been made to prepare an estimate of the cost of production of liquid ensilage and solid feed mix.