Off-Line Determination of the Optimal Command Policies for a Sludge Drying Application

The main objective of this work is to develop, using a predictive control method, an off-line determination of the operating parameters for a sludge drying stage. At each time step, two operating parameters are identified by simultaneously minimizing three objective functions over a finite horizon. A laboratory dryer is briefly presented and used, in order to evaluate the suitability of the direct model employed to simulate sludge drying. Surface temperature, drying kinetics, and evaporated mass flux obtained from experimental measurements are compared to numerical simulations. Afterward, the optimization procedure is carried out and the results are discussed.     

第8届国际景观双年展

第1届欧洲风景园林双年展始于1999年,这在当时属于首创,同时奠定了我国与欧洲互相交流风景园林理念的热情与决心。从那时以后,这一事件成为了风景园林师、风景园林系学生的交集点,以及宣传欧洲风景园林行业重要性的工具。显然,若非以下各组织单位的支持与合作,双年展将不可能得到巩固与发展：     

Continuous Synthesis of Organozinc Halides Coupled to Negishi Reactions

The Negishi cross‐coupling is a powerful C C bond forming reaction. The method is less commonly used relative to other cross‐coupling methods in part due to lack of availability of organozinc species. While organozinc species can be prepared, problems with reproducibility and handling of these sensitive species can complicate these reactions. Herein, we describe the continuous formation, using an activated packed‐bed of metallic zinc, and subsequent use of organozinc halides. We demonstrate that a single column of zinc can provide excellent yields of organozinc halides and that they can be used downstream in subsequent Negishi cross‐couplings. The preparation of the zinc column and the scope of the reaction are discussed.

     

Synthesis of Dihydroisobenzofurans via Palladium‐Catalyzed Sequential Alkynylation/Annulation of 2‐Bromobenzyl and 2‐Chlorobenzyl Alcohols under Microwave Irradiation

The palladium‐catalyzed synthesis of dihydroisobenzofurans has been performed by sequential Sonogashira cross‐coupling/cyclization reactions between terminal alkynes and 2‐(hydroxymethyl)bromo‐ and chlorobenzenes in methanol as solvent at 130 °C under microwave irradiation. A 4,4′‐dichlorobenzophenone oxime‐derived chloro‐bridged palladacycle is an efficient pre‐catalyst to perform this tandem process using 2‐dicyclohexylphosphanyl‐2′,4′,6′‐triisopropylbiphenyl (Xphos) as ancillary ligand and potassium hydroxide as base in the absence of a copper cocatalyst. Under these conditions, functionalized 2‐bromo‐ and 2‐chlorobenzaldehydes are also suitable partners in the domino process affording phthalans in good yields. All the reactions can be performed under air and employing reagent‐grade chemicals under low loading conditions (1 mol% Pd).

     

Neurofuzzy model based predictive control for thermal batch processes

In many cases, it is difficult to derive a precise mathematical model, based on first principles, for a given process. Besides, the computation of the solution of models obtained through this methodology may require a large computational effort making them useless for real time tasks like control or optimization. Neurofuzzy modelling, which permits an easy way to derive successful models, is a good alternative which can be employed to overcome such limitations.In this paper, together with the neurofuzzy modelling, several strategies based on non-linear predictive control are presented. The low computational cost associated with neurofuzzy models and controllers makes them suitable candidates to be implemented into industrial Programmable Logic Controllers (PLC). Both the model and controllers are validated and implemented in a pilot plant for the thermal sterilization of solid canned food in steam retorts and based on the results, a comparison between the different predictive control strategies is presented.     

Stress corrosion cracking mechanism of prestressing steels in bicarbonate solutions

Prestressing steels occasionally fail by a process named “stress corrosion cracking”. This process has not been fully elucidated and several theories exists in order to explain the cases in which real structures have collapsed. This paper briefly mentions the different theories and identifies the progress in understanding whether it is necessary to use a testing method, which is able to separate the different steps and mechanisms contributing to the failures.This paper presents the methodology used for inducing controlled localized attack to study the susceptibility of the high strength steels resistance to stress corrosion cracking (SCC). The method is designed to study the growth of cracks initiated from a mechanical notch; the crack is not produced by fatigue.It consists of several stages: coating of the bar with epoxy resin, generation of a small notch, constant load and controlled potential test in the media, mechanical test in air and fractographic study. It allows us to calculate the crack propagation rate and the fracture toughness in the same test.Finally, it has been possible to apply the surface mobility mechanism (SMM) in order to identify the SCC mechanism that operates.     

Analysis of optochemical absorbance sensors based on bidimensional planar ARROW microoptics

A new approach for developing absorbance optochemical sensors is presented in this paper. It is based on a planar microoptic circuit where an optochemically active membrane, which responds selectively to a compound, is deposited in the device, yielding a part of the guiding planar structure. Light is propagated through the membrane, which changes its spectral absorption properties and controls the selectivity of the measurements by means of several immobilised compounds. This way, high sensitivity of the device can be easily obtained due to relatively long light paths through the membrane, and low response times can be achieved as the analyte diffusion occurs perpendicularly to the light path and through a thin membrane. Experimental results on measurements of the concentration of a specific ion in solution using the fabricated sensors are also presented.     

Effect of laser cleaning on granite color

This article presents the effect of laser radiation on the color of ornamental granites used for external cladding. The laboratory experimentation was undertaken on a widely used coarse‐grain granite commercially known as Rosa Porriño. The irradiation was carried out with a Q‐switched Nd:YAG laser at 1064 nm and several energy densities (fluences) on polished surfaces, dry and wet, uncoated, and artificially coated‐simulating a black crust. Laser effects on the granite surface were determined by color measurements with a colorimeter. These measurements made possible to determine probable damage due to laser radiation and the diverse response of different minerals. The analysis of the data also suggests potential causes for the color change and applicability limits of the technique. The a*‐parameter, or red–green component, is the most affected, leading to a change in h_ab (hue) and was interpreted as a result in variations in the Fe compounds, which strongly condition stone color. No significant changes in L* (luminosity or lightness) or C_ab* (chroma) may indicate no relevant alterations in the surface polish. When using laser irradiation to remove black layers on granite surfaces, variations of L* can be indicative of the cleaning effectiveness. This research results may be useful to select laser parameters when managing ornamental granite cleaning operations. However, they also suggest the need of further experimentation in specific techniques of analysis as well as different laser wavelengths. © 2007 Wiley Periodicals, Inc. Col Res Appl, 32, 152 – 159, 2007     

Mathematical Model of Biofiltration of VOCs: Effect of Nitrate Concentration and Backwashing

The affect of nitrate concentration and reactor backwashing on biofilter performance is evaluated using a dynamic mathematical model of the biodegradation process of volatile organic compounds in a trickle bed biofilter packed with uniform synthetic solids. Experimental observations from a bench-scale biofilter system treating ether were used to develop and validate the model. Experience acquired in biofiltration of volatile organic compounds has demonstrated that although these two factors—nitrate and backwashing—are secondary when organic packing material is used, they are essential when the packing media is synthetic. The operation of a synthetic media packed reactor requires the addition of nutrients necessary for biodegradation. Since nitrate was utilized as the nitrogen source in this system, it was included in the model as a limiting substrate (nutrient). A negative affect of excessive accumulation of biomass in the reactor on biofilter performance has also been observed in highly loaded synthetic media biofilters. This problem was solved by removing excessive biomass via full media fluidization and backwashing of the reactor. The affect of periodic backwashing was included in the model as a reduction in the biofilm thickness and a new approach to calculate the reactor specific surface area after backwashing. The unknown model parameters that correspond to nitrate limitations were estimated. The mathematical model was then used for simulation and analyses of the affect of these two factors on the biodegradation process.     

Rights and Argumentation in Open Multi-Agent Systems

As utility calculus cannot account for an important part of agents' behaviour in Multi-Agent Systems, researchers have progressively adopted a more normative approach. Unfortunately, social laws have turned out to be too restrictive in real-life domains where autonomous agents' activity cannot be completely specified in advance. It seems that a halfway concept between anarchic and off-line constrained interaction is needed. We think that the concept of right suits this idea. Rights improve coordination and facilitate social action in Multi-Agent domains.Rights allow the agents enough freedom, and at the same time constrain them (prohibiting specific actions). Besides, rights can be understood as the basic concept underneath open normativesystems where the agents reason about the code they must abide by. Typically, in such systems this code is underspecified. On the other hand, the agents might not have complete knowledge about the rules governing their interaction. Conflict situations arise, thus, when the agents have different points of view as to how to apply the code. We have extended Parsons's et al. argumentation protocol (Parsons et al. 1998a, b) to normative systems to deal with this problem.