Optimal filtering,fault detection and isolation for linear discrete‐time systems in a noisy environment

In this paper the state observer design and the fault detection and isolation problems are investigated in the context of linear discrete‐time state‐space models whose state equations are affected by (actuator) faults and disturbances. Model as well as measurement errors, described as zero‐mean white Gaussian noise, are also assumed to act additively on the state and on the output equations, respectively. Upon introducing several deterministic and stochastic goals, that constitute the mathematical formalization of very natural and practical requirements, necessary and sufficient conditions for the existence of an asymptotic state observer and an observer‐based fault detector and isolator, that achieve the above goals, are finally derived and a constructive procedure is described. Copyright © 2003 John Wiley & Sons, Ltd.     

An Experimental Study on the Air-Side Heat Transfer Coefficient and the Thermal Contact Conductance in Finned Tubes

The objective of this experimental study is to evaluate the heat transfer coefficient outside a tube with annular transverse fins, derived from strips of copper mechanically bound and coupled outside. Water is used as the heating medium, in turbulent conditions and flowing at different temperatures inside the tube. Petukhov's correlation has been selected to calculate the water heat transfer coefficient in the tube. The experimental data obtained are compared with a correlation from literature, and a similar trend is observed. A fitting of the data provides a correlation for the three tubes of different external diameter (30 mm, 22 mm, and 15.6 mm) that agrees very well with the experimental values. The thermal contact conductance is identified as the main reason for the difference between data and the original Briggs and Young correlation. An estimation of the contact conductance between fins and tubes provides values between 3500 and 11000 W/m²-K, slightly increasing with the air Reynolds number (based on the external diameter of the tube), whose range is 2000 to 8000. The thermal contact resistance is estimated and its importance is confirmed, contributing 30 to 50% to the total air-side thermal resistance in the tubes used in the experiments.     

Cosmic Low Temperature Physics: Making Molecules on Stardust

The lightest, simplest and the most abundant molecule in the universe, molecular hydrogen, is one of the most important in the physical and chemical evolution of the Cosmos: it is an essential ingredient in star formation by facilitating the cooling of a gravitationally collapsing cloud; and it enters, either neutral or charged, in most reactions to produce other molecules in space. Through its transitions, we learn about the physical and chemical environments it finds itself in. Its formation requires the help of sub-micron size dust grains, particles in interstellar space that once originated in the ejecta of late type stars, or in novae and supernovae. Until a decade and a half ago, little was known how this molecule is formed in interstellar space. Here I review experimental and theoretical studies of the formation of astrophysically important molecules, and molecular hydrogen in particular, on analogs of interstellar dust grains at low temperature. I will show that these studies touch important and still little understood aspects of elementary processes of atoms and molecules on surfaces at low temperature.     

A simple mechanical technique to obtain carbon nanoscrolls from graphite nanoplatelets

A simple approach for the bulk production of carbon nanoscrolls (CNSs) is described. This method is based on the application of shear-friction forces to convert graphite nanoplatelets into carbon nanoscrolls using a bi-axially oriented polypropylene (BOPP) surface. The combined action of shear and friction forces causes the exfoliation of graphite nanoplatelets and the simultaneous roll-up of graphite layers. Evidence of the CNS formation is given by optical microscopy, scanning electron microscopy, and transmission electron microscopy. These investigations reveal that the CNSs have a long tube-like and fusiform structure with a hollow core surrounded by few layers of graphene. Micro-Raman spectroscopy shows that the produced structures are not defect free, and optical spectroscopy reveals distinctive features due to the presence of two weak absorption bands at 224 and 324 nm.     

Terpenoids are widespread in actinomycetes: a correlation of secondary metabolism and genome data

The genomes of all bacteria with publicly available sequenced genomes have been screened for the presence of sesquiterpene cyclase homologues, resulting in the identification of 55 putative geosmin synthases, 23 homologues of 2-methylisoborneol synthases, and 98 other sesquiterpene cyclase homologues. Most of these enzymes by far were found in actinomycetes. The terpenoid volatiles from 35 strains, including 31 actinomycetes and four strains from other taxa, were collected by using a closed-loop stripping apparatus and identified by GC-MS. All of these bacteria apart from one strain encode sesquiterpene cyclase homologues in their genomes. The identified volatile terpenoids were grouped according to structural similarities and their biosynthetic relationship, and the results of these analyses were correlated to the available genome information, resulting in valuable new insights into bacterial terpene biosynthesis.     

Preparation,Characterization, and Properties of 7-Nitrotetrazolo[1,5-f ]furazano[4,5-b]pyridine 1-Oxide

ABSTRACT

The synthesis, characterization, and properties of 7-nitro-tetrazolo[1,5-f]furazano[4,5-b]pyridine 1-oxide (NFP) are reported. NFP is prepared by the diazotization of 3,6-di(hydrazino)-3,5-di(nitro)pyridine followed by the extrusion of molecular dinitrogen and ring closure.     

Synthesis of 3,6-bis(3-azido-1,2,4-triazol-1-yl)-1,2,4,5-tetrazine

The synthesis of 3,6-bis(3-azido-1,2,4-triazol-1-yl)-1,2,4,5-tetrazine (3) (BATTz) is described. The physical and explosive sensitivity properties of this material were determined. The heat of formation was measured to be 1376 kJ/mol by combustion calorimetry. Additionally, X-ray crystallography confirmed the structure of this high-nitrogen primary explosive.     

Development of enzyme-linked immunosorbent assays for Sudan dyes in chilli powder,ketchup and egg yolk

This study aimed at developing sensitive competitive enzyme-linked immunosorbent assays (ELISAs) for the banned Sudan dyes using polyclonal antibodies. Three different formats were developed and characterized in terms of sensitivity, selectivity and rapidity. A competitive indirect ELISA was developed, which showed an IC₅₀ of 3.8 µg l^–1. Two competitive direct ELISAs were also developed, in which the antibody was added before or simultaneously with the other reagents; the first showed an IC₅₀ of 8.3 µg l^–1 and the latter showed an IC₅₀ of 4.9 µg l^–1. Nevertheless, considering dilution of extracts which is needed to offset matrix interference, the limits of detection of the three formats were substantially the same (10 µg kg^–1). The antibodies in all three test formats were able to recognize Sudan I and partially Sudan II, III and IV; no cross-reactivity was observed with the five edible dyes. Twenty food samples, including chilli powder, paprika, ketchup, and egg, were extracted by a simple sample preparation and very limited dilution. Extracts were analyzed by the developed competitive direct ELISA with the simultaneous addition of reagents. A good correlation was observed (y = 1.19x–10.0, r ² = 0.991, n = 20) when the data was compared with that obtained through a conventional HPLC method.     

布宜诺斯艾利斯的绿色屋顶

项目地点:阿根廷布宜诺斯艾利斯项目类型:城市干预设计开工日期:未定这是为一项针对公共政策而设计的概念性项目,旨在大规模地推动布宜诺斯艾利斯现有住宅屋顶花园的建设。该项目获2005年豪瑞可持续建筑大奖赛拉丁美洲区金奖。