Hierarchical representation of complex systems for supporting human decision making

The work presented in this paper is devoted to intelligent on-line supervision tools. In the proposed approach, the human operator remains in the decision loop, at the highest level, and acts on the process. To help operators make decisions, process knowledge is represented with a model whose complexity can be adapted on line to the operation needs at the request of the operator. The model thus helps to focus only on the phenomena that are relevant at a given time. To give the model explanatory capacity, it is represented as a causal directed graph, and allows the representation of temporal phenomena, which is fundamental for dynamic monitoring. A hierarchical representation of the functional properties of the process is proposed. The conception of a hierarchy of causal models with a top-down analysis is discussed. Path algebra is used to construct a higher-level graph on-line at the request of the operator from the most detailed graph, while conserving the semantics of the latter. No intermediate level is defined a priori; only the highest and lowest level graphs are fixed: the others are constructed dynamically. Finally, a study of how graphs can convey information on the dynamics of the process for approximate temporal reasoning that is largely sufficient for supervision purposes is analyzed. An example of a causal graph hierarchy for a nuclear process illustrates the method. As a final point, the use of such causal graphs in advanced industrial supervision tools is considered.     

Environmental and economic feasibility of sugarcane ethanol for the Mexican transport sector

This study analyzes the environmental and economic feasibility of ethanol produced from sugarcane for use as a potential gasoline substitute in the Mexican transport sector from 2010 to 2030. One scenario was created by projecting the historical trend of energy demand assuming that a fraction of this demand is satisfied with ethanol produced from the cultivation of 2.9 million hectares of sugarcane. A life cycle study was performed according to the recommendations from the European Union Directive on Renewable Energies (that include direct land use change emissions) and was used to estimate life cycle Greenhouse gas (GHG) emissions. The method used by Fingerman et al. (2010) was adopted to estimate the water consumption. In the economic analysis, the production cost of ethanol was calculated, and a mitigation cost for carbon dioxide equivalent emissions was estimated. The potential for employment generation was also estimated. The results demonstrate that water use increases by 29.4 times and that the costs increase by 10,706 million USD with the alternative scenario. This scenario, however, has the potential to create 560,619 direct jobs. Furthermore, GHG mitigation is confirmed since the reference scenario resulted in GHG gasoline life cycle emissions of 78.7 kgCO_2e/GJ while the alternative scenario resulted in Ethanol GHG emissions in the life cycle of 57.52 kgCO_2e/GJ.     

Metal–thermoplastic urethane hybrids in environmental exposure

The long-term properties of injection moulded metal–thermoplastic urethane (TPU) hybrids were studied. The hybrids manufactured with different metal substrates, namely copper, stainless steel and aluminium, were compared, using two surface modifications for copper and stainless steel. N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane was used as coupling agent. It is concluded that the bond mechanism of the silane on different substrate differs, affecting the long-term behaviour of the respective hybrids. The thick layers of silane coupling agent on copper and stainless steel are sensitive to hydrolysis; thus the resistance in humid conditions is quite low. The high temperature exposure increased the bond strength and the fraction of cohesive failure in TPU in copper–TPU, aluminium–TPU and polished steel–TPU hybrids. The last one has native mixed oxide, contrary to controlled oxidised stainless steel, where adhesion decreased after any long-term experiments. This is suggested to derive from hydrogen bonding of the coupling agent to the surface Fe₂O₃ oxide.     

Reuse of water purification sludge as raw material in cement production

The feasibility of partial replacement of siliceous raw material for cement production with water purification sludge (WPS) was investigated by X-ray diffraction, free-lime analysis, compressive strength testing and toxicity characteristics leaching procedure (TCLP). It is found that WPS has no negative effects on the consumption of free lime and the formation of clinker minerals. The samples with WPS from 4 to 10 wt.% have higher 3 days and 7 days strengths than the control. After 28 days, however, only WPS replacements <7% increased the strength of samples. It is noteworthy that heavy metals in WPS were almost completely incorporated into the clinkers, and up to 28 days the heavy metals were not detected in the leachates. From the above results of clinker minerals, compressive strength and leaching tests, it can be concluded that WPS has the potential to be utilized as an alternative raw material in cement production.     

Reduction of greenhouse gases using renewable energies in Mexico 2025

This study presents three scenarios relating to the environmental futures of Mexico up to the year 2025. The first scenario emphasizes the use of oil products, particularly fueloil, and represents the energy policy path that was in effect until 1990. The second scenario prioritizes the use of natural gas, reflecting the energy consumption pattern that arose in the mid-1990s as a result of reforms in the energy sector. In the third scenario, the high participation of renewable sources of energy, in particular renewable hydrogen, is considered feasible from a technical and economic point of view. The three scenarios are evaluated up to the year 2025 in terms of greenhouse gases (GHG), acid rain precursor gases (ARPG), and environment–energy intensity factors.     

Dry etching mechanism of copper and magnetic materials with UV illumination

To better understand the dry etching of copper and magnetic materials with UV illumination an etch mechanism is proposed based on the subprocesses occurring in an inductively coupled plasma (ICP) reactor. The photo-dissociation of Cl₂ provides chlorine-enriched environment near the surface, and UV photons enhance the surface reaction, leading to fast formation of metal chlorides on the surface with low activation energy. The overall etching process of metals with UV illumination is limited by absorption capacity of UV radiation by reaction products. The proposed etch mechanism also showed the potential gaseous etch products are CuCl, CuCl₂, Cu₂Cl, Cu₂Cl₂, Cu₂Cl₃, Cu₃Cl₂ and Cu₃Cl₃, while the dominant gas species are CuCl₂ and Cu₂Cl₃ with UV illumination. The ICP etching of magnetic materials in Cl₂/Ar discharges with UV illumination showed no enhancement in etch rate for NiFe, but a substantial enhancement for NiFeCo mainly due to the lower binding energy of NiFeCo relative to NiFe.     

Structural and physical properties of dietary fibres,and consequences of processing on human physiology

Dietary fibre encompasses very diverse macromolecules exhibiting a large variety of physico-chemical properties. They might be naturally present in the food (in cell walls of vegetables and fruits, for instance) or introduced in the food to improve their nutritional properties (e.g. bran in bread products) or their physical characteristics (e.g. gelling agents or improved resistance to storage). The properties that are nutritionally relevant are mainly the particle size and bulk volume, the surface area characteristics, the hydration and rheological properties, and the adsorption or entrapment of minerals and organic molecules. Amongst these properties, the viscosity and ion exchange capacity are the main contributors to metabolic effects (glucose and lipid metabolisms) whereas fermentation pattern, bulking effect and particle size are strongly involved in effects on colonic function. Technological treatments can modify the physico-chemical properties of the fibre. This can be further exploited to optimise both their techno-functional and physiological properties.     

Using object-oriented technology to design efficient IEEE-488.2 (GPIB) interface instruments

IEEE-488.2 interface (or popularly known as GPIB interface) -based instruments are very common in the test and measurement industry. The most important characteristics of the firmware for such instruments are small code size and ease of implementation and maintenance. Object-oriented (OO) techniques can be used to exploit their inherent advantages and the paper demonstrates the design of firmware for an IEEE-488.2-based instrument using OO techniques. The advantages of encapsulation allow for ease of comprehension besides ease of implementation and maintenance. This design was used to implement the firmware in a high-end test and measuring instrument and the advantages that ensued are discussed. As a consequence, an inadequacy in the IEEE-488.2 standard was detected which is also pointed out in the paper.