Minimum-energy state estimation for systems with perspective outputs

This paper addresses the state estimation of systems with perspective outputs. We derive a minimum-energy estimator which produces an estimate of the state that is "most compatible" with the dynamics, in the sense that it requires the least amount of noise energy to explain the measured outputs. Under suitable observability assumptions, the estimate converges globally asymptotically to the true value of the state in the absence of noise and disturbance. In the presence of noise, the estimate converges to a neighborhood of the true value of the state. These results are also extended to solve the estimation problem when the measured outputs are transmitted through a network. In that case, we assume that the measurements arrive at discrete-time instants, are time-delayed, noisy, and may not be complete. We show that the redesigned minimum-energy estimator preserves the same convergence properties. We apply these results to the estimation of position and orientation for a mobile robot that uses a monocular charged-coupled device (CCD) camera mounted on-board to observe the apparent motion of stationary points. In the context of our application, the estimator can deal directly with the usual problems associated with vision systems such as noise, latency and intermittency of observations. Experimental results are presented and discussed.     

Degradation of wine industry wastewaters by photocatalytic advanced oxidation.

Wine industry wastewaters contain a high concentration of organic biodegradable compounds as well as a great amount of suspended solids. These waters are difficult to treat by conventional biological processes because they are seasonal and a great flow variation exists. Photocatalytic advanced oxidation is a promising technology for waters containing high amounts of organic matter. In this study we firstly investigated the application of H2O2 as oxidant combined with light (artificial or natural) in order to reduce the organic matter in samples from wine industry effluents. Secondly, we studied its combination with heterogeneous catalysts: titanium dioxide and clays containing iron minerals. The addition of photocatalysts to the system reduces the required H2O2 concentration. Although the H2O2/TiO2 system produces higher efficiencies, the H2O2/clays system requires a H2O2 dosage between three and six times lower.     

An Investigation of Milk Powders Produced by a Laboratory-Scale Spray Dryer

A mini spray dryer has been used to investigate morphological changes that occur to milk particles during the spray drying process. We have found that the mini spray dryer is ideal for such investigations, because phenomena such as skin and vacuole formation in particles can be analyzed without the added complication of particle agglomeration, which only occurs in much larger spray dryers where particle number concentrations are higher. We have confirmed observations made by various researchers that the bulk density of spray-dried milk powder is greatly affected by the drying temperature, due to the strong influence of the latter on the porosity of the particles. In addition, we have attempted to explain observations made by various workers that fat accumulates preferentially at the surface of a particle during drying by postulating that fluid fat is transported towards the surface, via a network of cracks and pores, by the development of a vacuole overpressure which is also responsible for the inflation of the particle. Finally, we have shown that milk powders can be spray dried a second time, by reconstitution with water, with no change to the thermodynamic characteristics of the resultant powder. Thus, milk concentrates for spray drying research can be prepared from already-spray-dried milk powders rather than using the more arduous evaporation method to concentrate unprocessed milk.     

Acidogenic fermentation of blended food‐waste in combination with primary sludge for the production of volatile fatty acids

The performance of a laboratory‐scale anaerobic acidogenic fermenter fed with a mixture of blended kitchen food‐waste and primary sludge from a sewage treatment plant was investigated for the production of volatile fatty acids (VFA). The operating variables for acidogenic fermentation were kitchen food‐waste content (10 and 25 wt %), hydraulic retention time (HRT: 1, 3 and 5 days), temperature (ambient: 18 ± 2 °C, and mesophilic: 35 ± 2 °C) and pH (varied from 5.2 to 6.7). The experimental results indicated that effluent VFA concentrations and VFA production rates were higher at ambient temperature than at mesophilic conditions. The net amount of VFA with 10 wt % food‐waste increased up to 920 mg dm^?3 with an increase of HRT, but contrasting results (a decrease of 2610 mg dm^?3) were found due to the conversion of VFA into biogas in the case of 25 wt % food‐waste, which increased significantly at HRT of 3–5 days. In terms of biogas composition (CO₂ and CH₄), the organic matter was converted into CO₂ through the oxidative pathway by facultative species at low temperature while mesophilic temperature and optimum pH (6.3–7.8) played a pivotal role in increasing rate of conversion of VFA into biogas by methanogenesis. Rates of VFA production and their conversion are dependent on the food‐waste content in the mixture. Yet, the higher concentration of food‐waste (25% compared with 10%) did not produce VFA proportionally due to the increased rate of conversion of VFA into gaseous products. The maximum VFA production rate (0.318 g VFA_produced g^?1 VS_fed day^?1) was achieved in the 10 wt % food‐waste at ambient temperature and at a 5‐day HRT. Copyright © 2005 Society of Chemical Industry     

A brief introduction to functional MRI.

IEEE Engineering in Medicine and Biology Magazine focuses on modern methods for the analysis of data from functional magnetic resonance imaging (fMRI) studies. Accordingly, the guest editors have seen fit to begin with a brief article on the history, mechanisms and methods behind fMRI. This is followed by the presentation of recent significant progress in paradigm design for fMRI as well as development of other methods for assessing the functional anatomy of the human brain, such as diffusion tensor imaging, for mapping white matter fiber tracts. Thus, the future appears to promise a more integrative approach to functional brain imaging, in which data from multiple modalities are entered into comprehensive analyses of brain function and connectivity.     

Displacement Discontinuity Method for Fracture Mechanics Analysis of Reissner Plates: Static and Dynamic

This paper is concerned with the displacement discontinuity method applied to the shear deformable plates (Reissner’s and Mindlin’s theories) with cracks subjected to static and dynamic loads. Fundamental solutions of dislocation are derived using the Fourier transform method and the Laplace transformation technique. Boundary integral equations are presented in terms of rotations/displacement on the crack surfaces. The Chebyshev polynomials of the second kind are used to evaluate the integral equations with hypersingular kernels on the crack boundaries and determine the stress intensity factors at the crack tips. Comparisons are made with other numerical solutions to demonstrate the proposed method is accurate both for static and dynamic problems.     

Effects of solid retention time on the performance of submerged anoxic/oxic membrane bioreactor.

In this study, four similar bench-scale submerged Anoxic/Oxic Membrane Bioreactors (MBR) were used simultaneously to investigate the effects of solids retention time (SRT) on organic and nitrogen removal in MBR for treating domestic wastewater. COD removal efficiencies in all reactors were consistently above 94% under steady state conditions. Complete conversion of NH(4+)-N to NO(3-)-N was readily achieved over a feed NH(4+)-N concentration range of 30 to 50 mg/L. It was also observed that SRT did not significantly affect the nitrification in the MBR systems investigated. The average denitrification efficiencies for the 3, 5, 10 and 20 days SRT operations were 43.9, 32.6, 47.5 and 66.5%, respectively. In general, the average effluent nitrogen concentrations, which were mainly nitrate, were about 22.2, 27.6, 21.7 and 13.9 mg/L for the 3, 5, 10 and 20 days SRT systems, respectively. The rate of membrane fouling at 3 days SRT operation was more rapid than that observed at 5 days SRT. No fouling was noted in the 10 days and 20 days SRT systems during the entire period of study.     

Gorillas (Gorilla gorilla) and Orangutans (Pongo pygmaeus) Encode Relevant Problem Features in a Tool-Using Task.

Two important elements in problem solving are the abilities to encode relevant task features and to combine multiple actions to achieve the goal. The authors investigated these 2 elements in a task in which gorillas (Gorilla gorilla) and orangutans (Pongo pygmaeus) had to use a tool to retrieve an out-of-reach reward. Subjects were able to select tools of an appropriate length to reach the reward even when the position of the reward and tools were not simultaneously visible. When presented with tools that were too short to retrieve the reward, subjects were more likely to refuse to use them than when tools were the appropriate length. Subjects were proficient at using tools in sequence to retrieve the reward. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Detection of fatty acid beta-oxidizing syntrophic bacteria by fluorescence in situ hybridization.

A new 16S rRNA-targeted oligonucleotide probe, specific for the cluster of fatty acid beta-oxidizing syntrophic bacteria of the family Syntrophomonadaceae was designed for fluorescence in situ hybridization. This probe was evaluated with target as well as non-target cultures. Moreover this probe was assessed with butyrate and oleate degrading enrichment cultures and methanogenic sludges from full-scale plants. The results showed that the probe revealed the presence of fatty acid beta-oxidizing syntrophic bacteria in some of the samples analyzed. However, cell quantification was possible only in enrichment cultures and in a flocculent sludge from a reactor that treats lipid-rich wastewaters, but not in methanogenic granular sludges from upflow anaerobic sludge blanket reactors.     

Arthur Norberg, the Charles Babbage Institute, and the History of Computing

This issue of the IEEE annals of the history of computing originated with a desire to mark the retirement of Charles Babbage Institute founding director Arthur Norberg. In so doing, a number of Norberg's peers were invited to help celebrate and honor the CBI director's career while also appraising the history of computing field that Norberg helped create.