Dynamic data reconciliation: Alternative to Kalman filter

Process measurements are often corrupted with varying degrees of noise. Measurement noise undermines the performance of process monitoring and control systems. To reduce the impact of measurement noise, exponentially-weighted moving average and moving average filters are commonly used. These filters have good performance for processes under steady state or with slow dynamics. For processes with significant dynamics, more sophisticated filters, such as model-based filters, have to be used. The Kalman filter is a well known model-based filter that has been widely used in the aerospace industry. This paper discusses another model-based filter, the dynamic data reconciliation (DDR) filter. Both the Kalman and the DDR filters adhere to the same basic principle of using information from both measurements and models to provide a more reliable representation of the current state of the process. However, the DDR filter can more easily incorporated in a wide variety of model structures and is easier to understand and implement. Simulation results for a binary distillation column with four controlled variables showed that the DDR filters had equivalent performance to the Kalman filter in dealing with both white and autocorrelated noise.     

Complete amino acid sequence of Proteus mirabilis PR catalase. Occurrence of a methionine sulfone in the close proximity of the active site

The catalase of Proteus mirabilis PR, a peroxide-resistant (PR) mutant of Proteus mirabilis, binds strongly NADPH, which is a unique property among known bacterial catalases. The enzyme subunit consists of 484 amino acid residues for a mass of 55,647 daltons. The complete amino acid sequence was resolved through the combination of protein sequencing, mass spectrometry, and nucleotide sequencing of a PCR fragment. The sequence obtained was compared with that of other known catalases. Amino acids of the active site are all conserved as well as essential residues involved in NADPH binding. Among the amino acids interacting with the heme, a methionine sulfone was found at position 53, in place of a valine in most other catalases. The origin of oxidation of this methionine is unknown, but the presence of this modification could change iron accessibility by large substrates or inhibitors. This posttranslational modification was also demonstrated in the wild-type P. mirabilis catalase.     

Dynamic Characteristics of Solids Transportation in Rotary Dryers

An original method was proposed for the determination of the mean residence time in a continuous dryer, based on the step-change in the solids feed rate. The method has been validated through experiments performed in a pilot-scale rotary dryer. The effect of the solids flow rate, gas flow rate, dryer rotation speed, and dryer slope was quantified. Several design correlations to predict the residence time in rotary dryers were critically evaluated, and a new, more accurate correlation was derived.     

Human T lymphocyte proliferative response to resting porcine endothelial cells results from an HLA-restricted, IL-10-sensitive, indirect presentation pathway but also depends on endothelial-specific costimulatory factors

To investigate the mechanisms of cellular rejection in pig-to-human xenotransplantation, the proliferation of different human purified lymphocyte subpopulations in response to swine leukocyte Ag class II-negative porcine aortic endothelial cells (PAEC) was measured in the presence or absence of human autologous adherent cells (huAPC). CD8+ lymphocytes proliferated moderately in the absence of huAPC, and the immune response was slightly increased when huAPC were added. CD56+ lymphocytes failed to proliferate in response to PAEC whether huAPC were present or not. CD4+ lymphocytes alone did not proliferate in response to PAEC, but a strong proliferative response was observed in the presence of metabolically active huAPC. This response was totally abolished by mAbs directed against HLA class II molecules or by pretreatment of huAPC by human IL-10. Even in the presence of huAPC, CD4+ lymphocytes failed to respond to fixed PAEC or to PAEC-lysates, suggesting that PAEC must be viable to support lymphocyte proliferation. Finally, none of the nonendothelial porcine adherent cells tested was able to induce human lymphocyte proliferation, despite the fact that they also provided a large set of xenogeneic peptides. Our results show that the indirect presentation pathway of xenoantigens by huAPC to CD4+ lymphocytes is crucial in the response to porcine endothelial cells, and that IL-10 could be of therapeutic interest to prevent human lymphocyte activation by this pathway. Furthermore, we demonstrated that stimulatory signals specifically provided by endothelial cells are also necessary for this huAPC-restricted proliferative response.     

Silicon Substitution for Aluminum in Calcium Silicate Hydrates

²⁷Al MAS and multiquantum (MQ) MASNMR (magic-angle spinning nuclear magnetic resonance) spectroscopy were used to study the substitution of silicon by aluminum in calcium silicate hydrates (C-S-H), which are the main component of hydrated portland cement. Synthetic C-S-H samples were prepared, and their chemical stability was studied. Two-dimensional 3Q-MASNMR spectra revealed the chemical shift and quadrupolar parameters (delta_iso, nu_Q) that labeled aluminum sites in the C-S-H. Tetrahedral aluminum was observed in the bridging and nonbridging sites of the silicate chains.     

STUDY OF HEAT AND MASS TRANSFER DURING IR DRYING OF PAPER

A mathematical model has been developed to study the drying of paper using a gas-fired IR dryer. The model accounts for various phenomena : water and vapour mass transfer, conduction, convection and radiation heat transfer. The phenomenological equations are solved with a finite difference scheme, including a modified upwind differencing scheme to account for water migration within the paper sheet. The simulation results illustrate the basic underlying phenomena involved in IR paper drying and can be instrumental to the engineer to make the detailed analyses of such a drying process. A sensitivity analysis has shown that the drying rate is most sensitive to parameters governing the IR beat transfer process whereas the paper sheet temperature is most sensitive to parameters governing the mass transfer process with the surroundings.     

Effect of chemical treatments of sugar beet fibre on their physico-chemical properties and on their in-vitro fermentation

Chemically treated and dried sugar beet fibres were fermented in vitro in order to study the effects of chemical and physico-chemical parameters of dietary fibre on their colonic fermentation. Sugar beet fibre was treated with dilute alkali, removing mainly acetyl and methyl ester groups, and/or with dilute acids eliminating arabinose, galactose and certain uronic acid residues. The chemical treatments led to an increase in the hydration properties and fermentability by improvement of the accessibility of the remaining polysaccharides. However, if the chemically treated fibres were dried under harsh conditions (100°C), their hydration properties and their fermentability were limited, probably because of structural collapse of the fibre matrix. Whatever the conditions for chemical treatments and drying of the sugar beet fibres, it was possible to predict their fermentability from the water-binding capacity. Because of the relationship between the physiological effects of dietary fibres and the extent to which they are fermented, this result underlines the importance of the physico-chemical characterisation of the fibre in order to acquire a better knowledge of their physiological effects.     

ANALYTICAL TEMPERATURE DISTRIBUTION FOR MULTIDIMENSIONAL BODIES EXPOSED TO A CONSTANT SURFACE HEAT FLUX

For many decades, solutions for transient temperature distributions in multidimensional objects were determined by combining as a product the solutions of one-dimensional objects necessary to delimit the contour of these multidimensional objects. These product solutions are usually restricted to two types of boundary conditions: a constant wall temperature and a constant heat transfer coefficient

This paper considers the case of an object exposed to a constant surface heat flux. It is shown that when the surface of multidimensional object is submitted to a constant heat flux density, its temperature distribution can be obtained by the simple addition of one-dimensional temperature distributions. Only three one-dimensional solutions are necessary to solve all possible multidimensional problems. These are the solutions for a semi-infinite slab, an infinite plate and an infinite cylinder. The equations describing the temperature profile within each of these one-dimensional objects are presented as well as their graphical representations in a generalized form for rapid determination of temperatures.     

Antiproton-proton mass comparison with a radio-frequency mass spectrometer

The experiment aims at the reduction of the upper limit on a hypothetical CPT violation in the antiproton-proton system. A radio-frequency mass spectrometer (RFMS) has been designed and built to make the comparison of the charge to mass ratios of and p by measuring the ratios of the cyclotron frequencies of and H⁻ ions. At present, the RFMS is installed on-line to the LEAR facility at CERN. The resolving power has been found to be close to 3 × 10⁵ and it still could be improved. A decelerating system (RFQ) has been installed in order to decelerate antiprotons from 2 MeV to 200 keV and to match as well as possible the acceptance of the spectrometer. It is presently under test and data taking should take place in 1992.     

Photoperiodic modulation of monoamines and amino-acids involved in the control of prolactin and LH secretion in the ewe: evidence for a regulation of tyrosine hydroxylase activity

The aim of this study was to analyse medico-legal autopsy rates among Norwegian citizens who died in the two northernmost counties of Norway during the 20-year period 1973-1992. Medico-legal autopsy rate was defined as the number of medico-legal autopsies divided by the total number of deaths. The rates were calculated according to year of death, manner of death, sex, age, police district and county. The material included 1539 medico-legal autopsies. In the total 20-year period 37.9% (n = 1113) of the violent deaths and 1.2% (n = 426) of the natural deaths were subjected to medico-legal autopsy. The annual rates increased gradually up to 1987. In the last 5-year period 51.7% of the violent deaths and 2.1% of the natural deaths were subjected to medico-legal autopsy. Among violent deaths in this period the medico-legal autopsy rates were: suicides 65.7%, motor vehicle traffic accidents 58.3%, falls 8.6%, and other violent deaths 77.1%. Females dying after a fall and due to natural causes were significantly less frequently than males subjected to medico-legal autopsy. These two categories of death also revealed a significant decrease in autopsy rate with increasing age (age group 0-29, 30-59 and > or = 60 years) in each 5-year period. In cases of violent death the medico-legal autopsy rate according to police district varied from 24.1% to 88.9% in the last 5-year period. In conclusion, medico-legal autopsy rates depended on manner of death, sex, age and police district, besides changes in legislation.