A non-parametric semi-supervised discretization method

Semi-supervised classification methods aim to exploit labeled and unlabeled examples to train a predictive model. Most of these approaches make assumptions on the distribution of classes. This article first proposes a new semi-supervised discretization method, which adopts very low informative prior on data. This method discretizes the numerical domain of a continuous input variable, while keeping the information relative to the prediction of classes. Then, an in-depth comparison of this semi-supervised method with the original supervised MODL approach is presented. We demonstrate that the semi-supervised approach is asymptotically equivalent to the supervised approach, improved with a post-optimization of the intervals bounds location.     

Metal ion biosorption on chitosan for the synthesis of advanced materials

Chitosan is an aminopolysaccharide that binds metal ions through different mechanisms such as ion exchange, chelation or formation of ternary complex. The sorption performance depends on the characteristics of the solution (pH, presence of ligands, metal speciation) and the properties of the biopolymer (crystallinity, degree of deacetylation, molecular weight). Sorption performance is also controlled by the accessibility and availability of reactive groups (diffusion properties). These interactions chitosan/metal ions can be used for environmental applications (recovery of toxic or valuable metals) but also for the synthesis of new materials. Hybrid materials (chitosan/metal ion composites) can thus be used for manufacturing new sorbents with improved functionalities, supported catalysts, antimicrobial supports and sensors. The physical versatility of the biopolymer is an important criterion for designing these new materials: The conditioning of the material under the form of hydrogel beads, membranes, fibers and hollow fibers, foams and sponges enhances sorption performance and allows developing new applications.     

Evaluation of Light Scattering and Autofluorescent Properties of Brewer's Worts for Flow Cytometric Analysis of Yeast Viability

Flow cytometric methods for determining yeast viability are currently available. For effective analysis of yeast in breweries it is important that the light scattering properties of the sample medium (wort) do not interfere with that of target yeast cells. For this reason, a number of wort samples were analysed for their light scattering and autofluorescent properties, as well as their ability to bind the yeast viability dye, oxonol. Worts were found to produce light scattering that was sufficiently different from yeast, such that the two were clearly distinguishable by flow cytometry. Although oxonol bound to wort particles, computer software techniques allowed determination of yeast viability in worts.     

A dynamical model for the Utricularia trap

We propose a model that captures the dynamics of a carnivorous plant, Utricularia inflata. This plant possesses tiny traps for capturing small aquatic animals. Glands pump water out of the trap, yielding a negative pressure difference between the plant and its surroundings. The trap door is set into a meta-stable state and opens quickly as an extra pressure is generated by the displacement of a potential prey. As the door opens, the pressure difference sucks the animal into the trap. We write an ODE model that captures all the physics at play. We show that the dynamics of the plant is quite similar to neuronal dynamics and we analyse the effect of a white noise on the dynamics of the trap.     

Subsurface crack initiation and propagation mechanisms in gigacycle fatigue

In the very high cycle regime (N_f > 10⁷ cycles) cracks can nucleate on inclusions, “supergrains” and pores, which leads to fish-eye propagation around the defect. The initiation from an inclusion or other defect is almost equal to the total crack growth lifetime, perhaps much more than 99% of this lifetime in many cases. Integration of the Paris law allows one to predict the number of cycles to crack initiation. A cyclic plastic zone around the crack exists, and recording the surface temperature of the sample during the test may allow one to follow crack propagation and determine the number of cycles to crack initiation. A thermo-mechanical model has been developed. In this study several fish-eyes from various materials have been observed by scanning electron microscopy, and the fractographic results analyzed as they related to the mechanical and thermo-mechanical models.     

Remote plasma nitridation, deuterium anneal and pocket implant effects on NMOS hot carrier reliability

There are several advanced processes which are being actively studied as candidates for sub-0.25 μm technology. This paper studies the effects on NMOS hot carrier reliability from remote plasma nitrided oxide (RPNO), deuterium anneal and pocket implant. It is found that RPNO will not affect the SiO₂/Si interface. The hot carrier reliability is better for the same device channel current. This is due to making the effective oxide thickness thinner and achieving the same drive current with longer channel length. The deuterium anneal can improve the hot carrier reliability, even with nitride sidewall, if proper annealing is done. While the pocket implant can reduce short channel effects, the hot carrier lifetime is degraded unless optimization is done.     

Parallelization of structured,hierarchical adaptive mesh refinement algorithms

We describe an approach to parallelization of structured adaptive mesh refinement algorithms. This type of adaptive methodology is based on the use of local grids superimposed on a coarse grid to achieve sufficient resolution in the solution. The key elements of the approach to parallelization are a dynamic load-balancing technique to distribute work to processors and a software methodology for managing data distribution and communications. The methodology is based on a message-passing model that exploits the coarse-grained parallelism inherent in the algorithms. The approach is illustrated for an adaptive algorithm for hyperbolic systems of conservation laws in three space dimensions. A numerical example computing the interaction of a shock with a helium bubble is presented. We give timings to illustrate the performance of the method. Received: 28 April 1999 / Accepted: 25 November 1999     

弯曲荷载下混杂合成/金属螺栓连接的分析

采用试验研究和有限元分析方法,研究了混杂聚合物/金属螺栓连接的结构响应。主要研究目的是采用模数混合建筑方法为传统的船体建造技术提供比较方案。主要目标是实现防水混合连接的构思,为船体上使用的可移动板提供连接方法。改进的混合节点用于连接玻璃纤维增强复合材料板与金属底部基础。对各种几何尺寸及弯曲荷载的混合节点的性能进行了定量试验研究。试验结果显示,承受弯曲荷载时,带有金属盖板的节点比标准的螺栓节点具有更高的强度和转动刚度,同时也减小了节点的缝隙,因此提高了连接的整体防水能力。介绍了连接的局部壳单元和详细的实体单元有限元分析。简化的壳单元有限元模型被拓展到结构的整体模型中,并观察到了连接刚度与试验结果良好的相关性。采用详细的平面应变接触模型获取三维效果来预测连接的非线性响应。用本研究的结果选择连接的几何尺寸,并进行一个足尺四块板装配的静水压力试验。