Smart-MEMS based inertial measurement units: gyro-free approach to improve the grade

Microsystem Technologies - Inertial measurement units (IMU) are essentially a combination of acceleration and rotation rate sensors, generating position and attitude information. For tactical and...     

Behavior of Boron in Molten Aluminum and its Grain Refinement Mechanism

The mechanism of heterogeneous grain refining of aluminum by ultrafine elemental boron particles was investigated. In order to facilitate the observation of the boron-aluminum interface, a boron filament was introduced in a melt at 1013 K (740 °C) containing different levels of Ti. The Al/B interface was studied using transmission electron microscopy and different phases were identified using the electron diffraction method. The experimental results showed that boron is dissolved in pure aluminum while its dissolution is inhibited in presence of titanium solute. A thin layer of TiB₂ formed at the surface of boron thickens with residence time in the melt. The mechanisms by which aluminum is crystallized on boron are discussed.     

Evaluation of performance improvement by model predictive control in a renewable energy system with hydrogen storage

Nowadays islanded microgrids mostly rely on diesel generator. In order to reduce greenhouse emissions, two islanded microgrids with hydrogen storage have been installed and are currently working autonomously in Reunion Island and France. Energy management implemented on these stations fall in the myopic control category. This study aims to determine the performance improvement that could be achieve on such stations using model predictive control. Ability to supply to the loads and energy losses minimisation are our main objectives. Lifetime degradation is also taken in consideration. Simulations shows that significant improvement can be brought, with a 76% decrease of the station's defaults time and better fill rate of hydrogen tank and batteries. In the meantime, chemical and electrical losses are reduced by 38 and 11%, and the batteries degradations are decreased by around 1%. The relevance of taking into account the electrolyser and fuel cell degradations depends on the time-step of the control. These results give a performance target in order to implement a real-time model predictive control in the microgrids, and eventually can be used to better sizing of future microgrids with similar architecture.     

Real-time infinite horizon tracking with data fusion for augmented reality in a maritime operations context

In this paper, we propose a method for real-time horizon tracking (i.e., separation line between the sky and the sea) in a maritime operations context. We present the fusion of an image processing algorithm with the data obtained from the inertial measurement unit (IMU). The initial aim is to filter out environmental conditions using inertial information in order to combine a video stream with onboard electronic charts. This is achieved by the detection of the horizon with an image processing algorithm in an area defined by the IMU. We then present an evaluation of the algorithm with regard to the rate of detection of the horizon and the impact of the image resolution on the computational time. The purpose of developing this method is to create an augmented reality maritime operations application. We combine the video stream with electronic charts in a single display. We use the position of the horizon in the image to split the display into different areas. Then, we use transparency to display the video, the electronic charts or both.     

Electrostatic Halftoning

We introduce a new global approach for image dithering, stippling, screening and sampling. It is inspired by the physical principles of electrostatics. Repelling forces between equally charged particles create a homogeneous distribution in flat areas, while attracting forces from the image brightness values ensure a high approximation quality. Our model is transparent and uses only two intuitive parameters: One steers the granularity of our halftoning approach, and the other its regularity. We evaluate two versions of our algorithm: A discrete version for dithering that ties points to grid positions, as well as a continuous one which does not have this restriction, and can thus be used for stippling or sampling density functions. Our methods create very few visual artefacts, reveal favourable blue‐noise behaviour in the frequency domain, and have a lower approximation error under Gaussian convolution than state‐of‐the‐art methods.     

Sex differences in research funding,productivity and impact: an analysis of Québec university professors

Using the entire population of professors at universities in the province of Quebec (Canada), this article analyzes the relationship between sex and research funding, publication rates, and scientific impact. Since age is an important factor in research and the population pyramids of men and women are different, the role of age is also analyzed. The article shows that, after they have passed the age of about 38, women receive, on average, less funding for research than men, are generally less productive in terms of publications, and are at a slight disadvantage in terms of the scientific impact (measured by citations) of their publications. Various explanations for these differences are suggested, such as the more restricted collaboration networks of women, motherhood and the accompanying division of labour, women’s rank within the hierarchy of the scientific community and access to resources as well as their choice of research topics and level of specialization.     

Effect of processing procedures and conditions on structural,morphological, and rheological properties of polyethylene/polyamide/nanoclay blends

The article deals with the effect of processing procedures and conditions on structural, morphological, and rheological properties of ternary blends composed of polyethylene (PE), polyamide (PA)‐12, and organically modified montmorillonite nanoclay with selective affinity. Samples were prepared from PE/PA and PA/PE blends, either by simultaneous mixing or from a polymer/clay masterbatch, using two processing conditions. The results have shown the existence of a weight fraction threshold, above which no significant processing effect was observed. Below this weight fraction threshold, the results tend to underline the significant role of two parameters that depend on processing procedures and/or conditions: the contact time between PE and PA phases and the contact time between clay and PA. Clay structure, blend morphology, and rheological properties were all shown to depend on these two parameters, and also on the nature of the matrix (PE or PA), because of the selective affinity of clay toward polymer phases. POLYM. ENG. SCI., 2011. © 2011 Society of Plastics Engineers     

Novel regioregular poly(3-hexylthiophene)-based polycationic block copolymers

Regioregular poly(3-hexylthiophene) has been successfully incorporated into various poly(N,N-dimethylamino-2-ethyl methacrylate)-based block copolymers, i.e., P3HT-b-PDMAEMA, via Grignard metathesis (GRIM) method and atom transfer radical polymerization (ATRP) reactions. The structure of the diblock copolymers was fully confirmed by FT-IR, ¹H NMR spectroscopy, gel permeation chromatography (GPC), and ultraviolet–visible spectroscopy (UV–vis). The recovered copolymers could be treated by protonation of the pending tertiary amine functions and depending on the relative content in PDMAEMA, the copolymers could be solubilized in more polar solvents where P3HT alone proved to be totally insoluble.