Moving Object Scanning Apparatus and Method

Apparatus for scanning a moving object includes a visible waveband sensor oriented to collect a series of images of the object as it passes through a field of view. An image processor uses the series of images to form a composite image. The image processor stores image pixel data for a current image and predecessor image in the series. It uses information in the current image and its predecessor to analyse images and derive likelihood measures indicating probabilities that current image pixels correspond to parts of the object. The image processor estimates motion between the current image and its predecessor from likelihood weighted pixels. It generates the composite image from frames positioned according to respective estimates of object image motion. Image motion may alternatively be detected be a speed sensor such as Doppler radar sensing object motion directly and providing image timing signals

R-matrix-Floquet theory of multiphoton processes:VIII. A linear equations method

A new linear equations method for calculating the R-matrix, which arises in the R-matrix-Floquet theory of multiphoton processes, is introduced. This method replaces the diagonalization of the Floquet Hamiltonian matrix by the solution of a set of linear simultaneous equations which are solved, in the present work, by the conjugate gradient method. This approach uses considerably less computer memory and can be readily ported onto parallel computers. It will thus enable much larger problems of current interest to be treated. This new method is tested by applying it to three-photon ionization of helium at frequencies where double resonances with a bound state and autoionizing states are important. Finally, an alternative linear equations method, which avoids the explicit calculation of the R-matrix by incorporating the boundary conditions directly, is described in an appendix.

Relative biological effectiveness (RBE) and out-of-field cell survival responses to passive scattering and pencil beam scanning proton beam deliveries

The relative biological effectiveness (RBE) of passive scattered (PS) and pencil beam scanned (PBS) proton beam delivery techniques for uniform beam configurations was determined by clonogenic survival. The radiobiological impact of modulated beam configurations on cell survival occurring in- or out-of-field for both delivery techniques was determined with intercellular communication intact or physically inhibited. Cell survival responses were compared to those observed using a 6 MV photon beam produced with a linear accelerator. DU-145 cells showed no significant difference in survival response to proton beams delivered by PS and PBS or 6 MV photons taking into account a RBE of 1.1 for protons at the centre of the spread out Bragg peak. Significant out-of-field effects similar to those observed for 6 MV photons were observed for both PS and PBS proton deliveries with cell survival decreasing to 50-60% survival for scattered doses of 0.05 and 0.03 Gy for passive scattered and pencil beam scanned beams respectively. The observed out-of-field responses were shown to be dependent on intercellular communication between the in-and out-of-field cell populations. These data demonstrate, for the first time, a similar RBE between passive and actively scanned proton beams and confirm that out-of-field effects may be important determinants of cell survival following exposure to modulated photon and proton fields

Reversal of optic disc cupping after glaucoma surgery analyzed with a scanning laser tomograph

Objective: To detect and quantitate changes in optic nerve morphology after glaucoma surgery using the Heidelberg Retina Tomograph (HRT, Heidelberg Instruments, Heidelberg, Germany). Design: Nonconsecutive observational case series. Participants and Intervention: The authors prospectively enrolled 21 adult patients undergoing incisional glaucoma surgery for progressive glaucoma damage. Quantitative analysis of the optic nerve head by scanning laser tomography and automated perimetry were performed before and after glaucoma surgery. Main Outcome Measures: Changes in optic nerve parameters were subjected to linear regression analysis with respect to percent of postoperative reduction of intraocular pressure (IOP), as well as with respect to age, refraction, preoperative cup:disc ratio, and change in visual field parameters. Results: Seventeen patients had pre- and postoperative images suitable for analysis. Mean IOP at the time of image acquisition before surgery was 30.5 ± 12 mmHg, and after surgery 11.8 ± 5.2 mmHg (mean follow-up, 26 ± 7 weeks). Eleven of 13 (85%) patients having IOP reduction of greater than 40% showed improvement in optic disc parameters. All four patients with less than 25% reduction in IOP showed worsening of most parameters. Changes in optic disc parameters were highly correlated with percent IOP reduction and with age. The parameters in which change most strongly correlated with percent change of IOP were cup area, rim area, cup:disc ratio, and mean cup depth (each, P <0.005). The age of the patient correlated highly with change in maximum cup depth (P <0.005). Refraction and clinically determined cup:disc ratio correlated poorly with changes in measured optic disc parameters. Clinical improvement in visual fields was correlated with the degree of improvement of cup:disc ratio (P = 0.025). Conclusion: Most patients showing a 40% lowering of IOP after glaucoma surgery show improved optic nerve morphology as measured by the HRT. The amount of improvement correlated highly with the percent reduction of IOP.

A current-driven instability in parallel, relativistic shocks

Recently, Bell ( 2004 Mon. Not. R. Astron. Soc. 353 550) has reanalysed the problem of wave excitation by cosmic rays propagating in the pre-cursor region of a supernova remnant shock front. He pointed out a strong, non-resonant, current-driven instability that had been overlooked in the kinetic treatments by Achterberg ( 1983 Astron. Astrophys. 119 274) and McKenzie and Volk ( 1982 Astron. Astrophys. 116 191), and suggested that it is responsible for substantial amplification of the ambient magnetic field. Magnetic field amplification is also an important issue in the problem of the formation and structure of relativistic shock fronts, particularly in relation to models of gamma-ray bursts. We have therefore generalized the linear analysis to apply to this case, assuming a relativistic background plasma and a monoenergetic, unidirectional incoming proton beam. We find essentially the same non-resonant instability observed by Bell and show that also, under GRB conditions, it grows much faster than the resonant waves. We quantify the extent to which thermal effects in the background plasma limit the maximum growth rate.

Two-dimensional images of dissolved sulfide and metals in anoxic sediments by a novel diffusive gradients in thin film probe and optical scanning techniques

A novel diffusive gradients in thin film probe developed comprises diffusive gel layer of silver iodide (AgI) and a back-up Microchelex resin gel layer. 2D high-resolution images of sulfide and trace metals were determined respectively on the AgI gel by densitometric analysis and on the Microchelex resin layer with laser-ablation-inductively-coupled plasma mass spectrometry (LA-ICP-MS).We investigated the validity of the analytical procedures used for the determination of sulfide and trace metals. We found low relative standard deviations on replicate measurements, linear trace-metal calibration curves between the LA-ICP-MS signal and the true trace-metal concentration in the resin gel, and a good agreement of the sulfide results obtained with the AgI resin gel and with other analytical methods. The method was applied on anoxic sediment pore waters in an estuarine and marine system. Simultaneous remobilization of sulfide and trace metals was observed in the marine sediment.

Enhancing Linear Programming with Motion Modeling for Multi-target Tracking

In this paper we extend the minimum-cost network flow approach to multi-target tracking, by incorporating a motion model, allowing the tracker to better cope with longterm occlusions and missed detections. In our new method, the tracking problem is solved iteratively: Firstly, an initial tracking solution is found without the help of motion information. Given this initial set of tracklets, the motion at each detection is estimated, and used to refine the tracking solution.
Finally, special edges are added to the tracking graph, allowing a further revised tracking solution to be found, where distant tracklets may be linked based on motion similarity. Our system has been tested on the PETS S2.L1 and Oxford town-center sequences, outperforming the baseline system, and achieving results comparable with the current state of the art.

Diamond microelectrodes for corrosion studies

Este trabalho teve como objetivos a produção, caracterização e aplicação de microelétrodos (MEs) de diamante como sensores amperométricos e potenciométricos em sistemas de corrosão nos quais a agressividade do meio e a presença de produtos de corrosão, constituem obstáculos que podem diminuir o desempenho, ou inviabilizar a utilização, de outros tipos de sensores. Os microeléctrodos são baseados em filmes finos de diamante dopado com boro (BDD – Boron Doped Diamond) depositados sobre fios de tungsténio afiados, através do método de deposição química a partir da fase vapor, assistida por filamento quente (HFCVD – Hot Filament Chemical Vapor Deposition). A otimização das diversas etapas de fabricação dos MEs deu origem ao desenvolvimento de um novo sistema de afiamento eletroquímico para obtenção destes fios e a várias opções para a obtenção dos filmes de diamante condutor e seu isolamento com resinas para exposição apenas da ponta cilíndrica. A qualidade cristalina dos filmes de diamante foi avaliada por espectroscopia de Raman. Esta informação foi complementada com uma caracterização microestrutural dos filmes de diamante por microscopia eletrónica de varrimento (SEM), em que se fez a identificação da tipologia dos cristais como pertencendo às gamas de diamante nanocristalino ou microcristalino. Os filmes de BDD foram utilizados na sua forma não modificada, com terminações em hidrogénio e também com modificação da superfície através de tratamentos de plasma RF de CF4 e O2 indutores de terminações C-F no primeiro caso e de grupos C=O, C-O-C e C-OH no segundo, tal como determinado por XPS. A caracterização eletroquímica dos MEs não modificados revelou uma resposta voltamétrica com elevada razão sinal/ruído e baixa corrente capacitiva, numa gama de polarização quasi-ideal com extensão de 3 V a 4 V, dependente dos parâmetros de crescimento e pós-tratamentos de superfície. Estudou-se a reversibilidade de algumas reações heterogéneas com os pares redox Fe(CN)6 3-/4- e FcOH0/+ e verificou-se que a constante cinética, k0, é mais elevada em elétrodos com terminações em hidrogénio, nos quais não se procedeu a qualquer modificação da superfície. Estes MEs não modificados foram também testados na deteção de Zn2+ onde se observou, por voltametria cíclica, que a detecção da redução deste ião é linear numa escala log-log na gama de 10-5-10-2 M em 5 mM NaCl. Realizaram-se também estudos em sistemas de corrosão modelares, em que os microeléctrodos foram usados como sensores amperométricos para mapear a distribuição de oxigénio e Zn2+ sobre um par galvânico Zn-Fe, com recurso a um sistema SVET (Scanning Vibrating Electrode Technique). Foi possível detetar, com resolução lateral de 100 μm, um decréscimo da concentração de O2 junto a ambos os metais e produção de catiões de zinco no ânodo. Contudo verificou-se uma significativa deposição de zinco metálico na superfície dos ME utilizados. Os MEs com superfície modificada por plasma de CF4 foram testados como sensores de oxigénio dissolvido. A calibração dos microeléctrodos foi efetuada simultaneamente por voltametria cíclica e medição óptica através de um sensor de oxigénio comercial. Determinou-se uma sensibilidade de ~0.1422 nA/μM, com um limite de deteção de 0.63 μM. Os MEs modificados com CF4 foram também testados como sensores amperométricos com os quais se observou sensibilidade ao oxigénio dissolvido em solução, tendo sido igualmente utilizados durante a corrosão galvânica de pares Zn-Fe. Em alguns casos foi conseguida sensibilidade ao ião Zn2+ sem que o efeito da contaminação superficial com zinco metálico se fizesse sentir. Os microeléctrodos tratados em plasma de CF4 permitem uma boa deteção da distribuição de oxigénio, exibindo uma resposta mais rápida que os não tratados além de maior estabilidade de medição e durabilidade. Nos MEs em que a superfície foi modificada com plasma de O2 foi possível detetar, por cronopotenciometria a corrente nula, uma sensibilidade ao pH de ~51 mV/pH numa gama de pH 2 a pH 12. Este comportamento foi associado à contribuição determinante de grupos C-O e C=O, observados por XPS com uma razão O/C de 0,16. Estes MEs foram igualmente testados durante a corrosão galvânica do par Zn-Fe onde foi possível mapear a distribuição de pH associada ao desenvolvimento de regiões alcalinas causadas pela redução do oxigénio, acima da região catódica, e de regiões ácidas decorrentes da dissolução anódica do ânodo de zinco. Com o par galvânico imerso em 50 mM NaCl registou-se uma variação de pH aproximadamente entre 4,8 acima do ânodo de zinco a 9,3 sobre o cátodo de ferro. A utilização pioneira destes MEs como sensores de pH é uma alternativa promissora aos elétrodos baseados em membranas seletivas.

High field chemistry with scanning probes

Fabricating Ge and Si integrated structures with nanoscale accuracy is a challenging pursuit essential for novel advances in electronics and photonics. While several scanning probe-based techniques have been proposed, no current technique offers control of nanostructure size, shape, placement, and chemical composition. To this end, atomic force microscope direct write uses a high electric field (> 109 V m-1) to create nanoscale features as fast as 1 cm s-1 by reacting a liquid precursor with a biased AFM tip. In this work, I present the first results on fabricating inorganic nanostructures via AFM direct write. Using diphenylgermane (DPG) and diphenylsilane (DPS), carbon-free germanium and silicon nanostructures (SIMS, x-ray PEEM) are fabricated. For this chemistry, I propose a model that involves electron capture and precursor fragmentation under the high electric field. To verify this model, experimental data and simulations are presented. High field chemistry for DPG and DPS has also been demonstrated for both sequential deposition and the creation of nanoscale heterostuctures, in addition to microscale deposition using a flexible stamp approach. This high field chemistry approach to the deposition of organometallic precursors could offer a low-cost, high throughput alternative for future optical, electronic, and photovoltaic applications.

Adaptive-threshold region merging via path scanning

Region merging algorithms commonly produce results that are seen to be far below the current commonly accepted state-of-the-art image segmentation techniques. The main challenging problem is the selection of an appropriate and computationally efficient method to control resolution and region homogeneity. In this paper we present a region merging algorithm that includes a semi-greedy criterion and an adaptive threshold to control segmentation resolution. In addition we present a new relative performance indicator that compares algorithm performance across many metrics against the results from human segmentation. Qualitative (visual) comparison demonstrates that our method produces results that outperform existing leading techniques.

Transformador diferencial de variação linear: condicionamento de sinal e desmodulação síncrona

Dissertação para obtenção do grau de Mestre em Engenharia Eletrotécnica Ramo de Automação e eletrónica Industrial

Aplicação de um modelo de programação linear inteira mista (PLIM) na expansão da rede de distribuição de energia elétrica em Angola

Em Angola, apenas cerca de 30% da população tem acesso à energia elétrica, nível que decresce para valores inferiores a 10% em zonas rurais mais remotas. Este problema é agravado pelo facto de, na maioria dos casos, as infraestruturas existentes se encontrarem danificadas ou não acompanharem o desenvolvimento da região. Em particular na capital angolana, Luanda que, sendo a menor província de Angola, é a que regista atualmente a maior densidade populacional. Com uma população de cerca de 5 milhões de habitantes, não só há frequentemente problemas relacionados com a falha do fornecimento de energia elétrica como há ainda uma percentagem considerável de municípios onde a rede elétrica ainda nem sequer chegou. O governo de Angola, no seu esforço de crescimento e aproveitamento das suas enormes potencialidades, definiu o setor energético como um dos fatores críticos para o desenvolvimento sustentável do país, tendo assumido que este é um dos eixos prioritários até 2016. Existem objetivos claros quanto à reabilitação e expansão das infraestruturas do setor elétrico, aumentando a capacidade instalada do país e criando uma rede nacional adequada, com o intuito não só de melhorar a qualidade e fiabilidade da rede já existente como de a aumentar. Este trabalho de dissertação consistiu no levantamento de dados reais relativamente à rede de distribuição de energia elétrica de Luanda, na análise e planeamento do que é mais premente fazer relativamente à sua expansão, na escolha dos locais onde é viável localizar novas subestações, na modelação adequada do problema real e na proposta de uma solução ótima para a expansão da rede existente. Depois de analisados diferentes modelos matemáticos aplicados ao problema de expansão de redes de distribuição de energia elétrica encontrados na literatura, optou-se por um modelo de programação linear inteira mista (PLIM) que se mostrou adequado. Desenvolvido o modelo do problema, o mesmo foi resolvido por recurso a software de otimização Analytic Solver e CPLEX. Como forma de validação dos resultados obtidos, foi implementada a solução de rede no simulador PowerWorld 8.0 OPF, software este que permite a simulação da operação do sistema de trânsito de potências.

Linear Low Density Polyethylene-Biodegradability Using Bacteria from Marine Benthic Environment and Photodegradability Using Ultraviolet Light

Various compositions of linear low density polyethylene(LLDPE) containing bio-filler(either starch or dextrin)of various particle sizes were prepared.The mechanical,thermal,FTIR,morphological(SEM),water absorption and melt flow(MFI) studies were carried out.Biodegradability of the compositions were determined using a shake culture flask containing amylase producing bacteria(vibrios),which were isolated from marine benthic environment and by soil burial test. The effect of low quantities of metal oxides and metal stearate as pro-oxidants in LLDPE and in the LLDPE-biofiller compositions was established by exposing the samples to ultraviolet light.The combination of bio-filler and a pro-oxidant improves the degradation of linear low density polyethylene.The maleation of LLDPE improves the compatibility of the c blend components and thepro-oxidants enhance the photodegradability of the compatibilised blends.The responsibility studies on the partially biodegradable LLDPE containing bio-fillers and pro-oxidants suggest that the blends could be repeatedly reprocessed without deterioration in mechanical properties.

Modification of Linear Low Density Polyethylene for Improved Photo and Biodegradation

LLDPE was blended with poly (vinyl alcohol) and mechanical, thermal, spectroscopic properties and biodegradability were investigated. The biodegradability of LLDPE/PVA blends has been studied in two environments, viz. (1) a culture medium containing Vibrio sp. and (2) a soil environment over a period of 15 weeks. Nanoanatase having photo catalytic activity was synthesized by hydrothermal method using titanium-iso-propoxide. The synthesized TiO2 was characterized by X-Ray diffraction (XRD), BET studies, FTIR studies and scanning electron microscopy (SEM). The crystallite size of titania was calculated to be ≈ 6nm from the XRD results and the surface area was found to be about 310m2/g by BET method. SEM shows that nanoanatase particles prepared by this method are spherical in shape. Linear low density polyethylene films containing polyvinyl alcohol and a pro-oxidant (TiO2 or cobalt stearate with or without vegetable oil) were prepared. The films were then subjected to natural weathering and UV exposure followed by biodegradation in culture medium as well as in soil environment. The degradation was monitored by mechanical property measurements, thermal studies, rate of weight loss, FTIR and SEM studies. Higher weight loss, texture change and greater increments in carbonyl index values were observed in samples containing cobalt stearate and vegetable oil. The present study demonstrates that the combination of LLDPE/PVA blends with (I) nanoanatase/vegetable oil and (ii) cobalt stearate/vegetable oil leads to extensive photodegradation. These samples show substantial degradation when subsequent exposure to Vibrio sp. is made. Thus a combined photodegradation and biodegradation process is a promising step towards obtaining a biodegradable grade of LLDPE.

Self-consistent theory of current and voltage noise in multimode ballistic conductors

Electron transport in a self-consistent potential along a ballistic two-terminal conductor has been investigated. We have derived general formulas which describe the nonlinear current-voltage characteristics, differential conductance, and low-frequency current and voltage noise assuming an arbitrary distribution function and correlation properties of injected electrons. The analytical results have been obtained for a wide range of biases: from equilibrium to high values beyond the linear-response regime. The particular case of a three-dimensional Fermi-Dirac injection has been analyzed. We show that the Coulomb correlations are manifested in the negative excess voltage noise, i.e., the voltage fluctuations under high-field transport conditions can be less than in equilibrium.