Geometrical shape optimization in fluid mechanics using FreeFem++

Structural and Multidisciplinary Optimization - In this article, we present simple and robust numerical methods for two-dimensional geometrical shape optimization problems, in the context of...     

A robust algorithm for white blood cell nuclei segmentation

Multimedia Tools and Applications - Segmentation of white blood cell nucleus is a crucial step in white blood cell counting and classification system based on peripheral blood smear images. It is...     

High-level synthesis for FPGAs: code optimization strategies for real-time image processing

High-level synthesis (HLS) is a potential solution to increase the productivity of FPGA-based real-time image processing development. It allows designers to reap the benefits of hardware implementation directly from the algorithm behaviors specified using C-like languages with high abstraction level. In order to close the performance gap between the manual and HLS-based FPGA designs, various code optimization forms are made available in today’s HLS tools. This paper proposes a HLS source code and directive manipulation strategy for real-time image processing by taking into account the applying order of different optimization forms. Experiment results demonstrate that our approach can improve more effectively the test implementations comparing to the other optimization strategies.     

A second-order blind source separation method for bilinear mixtures

In this paper, we are interested in the problem of Blind Source Separation using a Second-order Statistics (SOS) method in order to separate autocorrelated and mutually independent sources mixed according to a bilinear (BL) model. In this context, we propose a new approach called Bilinear Second-order Blind Source Separation, which is an extension of linear SOS methods, devoted to separate sources present in BL mixtures. These sources, called extended sources, include the actual sources and their products. We first study the statistical properties of the different extended sources, in order to verify the assumption of identifiability when the actual sources are zero-mean and when they are not. Then, we present the different steps performed in order to estimate these actual centred sources and to extract the actual mixing parameters. The obtained results using artificial mixtures of synthetic and real sources confirm the effectiveness of the new proposed approach.     

Smoke gas analysis by Fourier transform infrared spectroscopy – summary of the SAFIR project results

The determination of toxic components from fire gases is difficult because the environment is hot, reactions are often temperature dependent, and a lot of soot may be produced. Due to the different properties of the gas components, a different time‐consuming procedure for each species has traditionally been used. The use of FTIR (Fourier transform infrared) spectrometers as a continuous monitoring technique overcomes many of the problems in smoke gas analyses. FTIR offers an opportunity to set up a calibration and prediction method for each gas showing a characteristic spectral band in the infrared region of the spectrum. The objective of the SAFIR project was to further develop the FTIR gas analysis of smoke gases to be an applicable and reliable method for the determination of toxic components in combustion gases related to fire test conditions. The optimum probe design, filter parameters and the most suitable sampling lines in terms of flow rate, diameter, construction material and operating temperature have been specified. In the large scale, special concern was given to the probe design and the effects of the probe location as well as practical considerations of the sampling line length. Quantitative calibration and prediction methods have been constructed for different components present in smoke gases. Recommendations on how to deal with interferents, non‐linearities and outliers have been provided and a verification method for the spectrometer for unexpected variations and for the different models have been described. FTIR measurement procedures in different fire test scenarios have been studied using the recommendations of this project for measurement techniques and analysis and an interlaboratory trial of the FTIR technique in smoke gas analysis was carried out to define the repeatability and reproducibility of the method in connection with a small scale fire test method, the cone calorimeter. Copyright © 2000 John Wiley & Sons Ltd.     

A fair method for centralized optimization of multi-TSO power systems

This paper addresses the problem of centralized optimization of an interconnected power system partitioned into several regions controlled by different transmission system operators (TSOs). It is assumed that those utilities have agreed to transferring some of their competencies to a centralized control center, which is in charge of setting the control variables in the entire system to satisfy every utility’s individual objective. This paper proposes an objective method for centralized optimization of such multi-TSO power systems, which relies on the assumption that each TSO has a real-valued optimization function focusing on its control area only. This method is illustrated on the IEEE 118 bus system partitioned into three TSOs. It is applied to the optimal reactive power dispatch problem, where the control variables are the voltage settings for generators and compensators. After showing that the method has some properties of fairness, namely freedom from envy, efficiency, accountability, and altruism, we emphasize its robustness with respect to certain biased behavior of the different TSOs.     

The fission yeast spindle orientation checkpoint: a model that generates tension?

In all eukaryotes, the alignment of the mitotic spindle with the axis of cell polarity is essential for accurate chromosome segregation as well as for the establishment of cell fate, and thus morphogenesis, during development. Studies in invertebrates, higher eukaryotes and yeast suggest that astral microtubules interact with the cell cortex to position the spindle. These microtubules are thought to impose pushing or pulling forces on the spindle poles to affect the rotation or movement of the spindle. In the fission yeast model, where cell division is symmetrical, spindle rotation is dependent on the interaction of astral microtubules with the cortical actin cytoskeleton. In these cells, a bub1-dependent mitotic checkpoint, the spindle orientation checkpoint (SOC), is activated when the spindles fail to align with the cell polarity axis. In this paper we review the mechanism that orientates the spindle during mitosis in fission yeast, and discuss the consequences of misorientation on metaphase progression.     

Failure mechanisms of H13 die on relation to the forging process – A case study of brass gas valves

In the hot forging industry, die life is an important process factor because of the cost involved in lost production, replacement of die blocks and operative handling of the dies. There is still no consensus, however, on the type of wear affecting dies or the dominant mechanisms for die failure, which varies from one situation to another. This metallographic study of a failed industrial hot forging die used to forge gas cylinder valves has indicated various failure modes. Although plastic deformation and thermal fatigue are usually quoted as the main causes of damage, oxidative and abrasive wear, fatigue cracking and chipping appeared to bet he most important in this study. Feedback coupling of fatigue and wear effects are detected. Detailed scanning electron microscopy observations and energy-dispersive X-ray and optical profilometry analysis suggest that these failures might very depending on their localisation on the die surfaces and show a complex mechanisms related to the variation of process parameters.     

Functionalized porous glass for the removal and the confinement of ruthenium from radioactive solutions

An original approach to immobilize ruthenium species and then transform them into RuO₂ nanoparticles is presented that uses hybrid-functionalized glasses. First, different chemical graftings of functional groups (acetylacetonate, amine, nitrile, pyridine and thiol) in porous glass were used to extract ruthenium-containing complexes ([Ru(CH₃N)₄Cl₂] and Ru(NO)(NO₃)₃) from solutions. The best functional groups to selectively coordinate Ru complexes and thus extract it from the solutions have been determined. Then, the obtained Ru-containing composite glass was heated under air to remove the organic species and to obtain RuO₂ nanoparticles inside a glass with centimetre scale geometric form. The as-obtained materials were studied by transmission electron microscopy (TEM), scanning electron microscopy (SEM), nitrogen physisorbtion measurements, elemental analysis and X-ray diffraction (XRD).