Automatic transformation of logic models within engineering of embedded mechatronical units

Engineering of manufacturing systems is one of the most important aspects within the life cycle of manufacturing systems in terms of cost. Within the engineering process, several engineering activities are executed by different experts commonly using specific tools for the design of the different parts of the system. To reduce engineering costs beneath, two main approaches arise. The first is based on the use of libraries of mechatronical units as reusable artifacts. In this case, manufacturing systems are represented as a hierarchy of mechatronic units. The second option is to achieve the seamless connection of the different engineering tools exploiting a common data exchange format. This latter approach allows avoiding both double engineering and faults within the engineering process. Within this paper, a novel approach combining both options is proposed, and its effects are analyzed through an example. It considers the application of mechatronical units within the engineering process of manufacturing systems as well as a common data exchange format for the logic information required for designing the control system within the engineering of manufacturing systems. The latter provides a data exchange format for the overall engineering process, including not only model information exchange but also its embedding. This paper discusses the benefits of the data exchange format for logic models in detail.     

Computation and visualization of the MacAdam limits for any lightness, hue angle, and light source

We present a systematic algorithm capable of searching for optimal colors for any lightness L* (between 0 and 100), any illuminant (D65, F2, F7, F11, etc.), and any light source reported by CIE. Color solids are graphed in some color spaces (CIELAB, SVF, DIN99d, and CIECAM02) by horizontal (constant lightness) and transversal (constant hue angle) sections. Color solids plotted in DIN99d and CIECAM02 color spaces look more spherical or homogeneous than the ones plotted in CIELAB and SVF color spaces. Depending on the spectrum of the light source or illuminant, the shape of its color solid and its content (variety of distinguishable colors, with or without color correspondence) change drastically, particularly with sources whose spectrum is discontinuous and/or very peaked, with correlated color temperature lower than 5500 K. This could be used to propose an absolute colorimetric quality index for light sources comparing the volumes of their gamuts, in a uniform color space.     

Tuning morphology of siloxane bond-based polybenzoxazines by controlling the sol–gel and curing processes

Novel polybenzoxazine/polysilsesquioxane nanocomposites were synthesized with uniform and reproducible structural morphology, high T_g, and good thermal stability. Polysilsesquioxane was oriented in a nanometer-size lamellar structure. Benzoxazine monomer based on silane (BA-3aptms) was synthesized by reaction between bisphenol A, 3-(trimethoxysilyl)propylamine, and paraformaldehyde in a 1:2:4 molar ratio. Four experimental conditions of the two stage sol–gel process for polysilsesquioxane were studied, and their effect on the material characteristics investigated. In the first stage, hydrolysis was favored, while the second stage mostly consisted of condensation. The reaction condition with the longest hydrolysis time allowed the increase of the concentration of silanol units and the selective condensation, favoring the formation of a higher amount of cage-like cyclic structures. In addition, this experimental procedure was well controlled so that the sol–gel and oxazine-ring opening reactions were extremely reproducible from batch to batch. All processes were monitored by Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis and dynamic mechanical thermal analysis, scanning electron and transmission electron microscopies, and X-ray diffraction. A chemometric approach based on a multivariate curve resolution model was applied to the FTIR spectra, which allowed the identification of four reaction components associated with the sol–gel and the curing processes.     

Crystallization and properties of poly(ethylene terephthalate) copolymers containing 5-tert-butyl isophthalic units

The influence of incorporating 5-tert-butyl isophthalic units (^tBI) in the polymer chain of poly(ethylene terephthalate) (PET) on the crystallization behavior, crystal structure, and tensile and gas transport properties of this polyester was evaluated. Random poly(ethylene terephthalate-co-5-tert-butyl isophthalate) copolyesters (PET^tBI) containing between 5 and 40 mol% of ^tBI units were examined. Isothermal crystallization studies were performed on amorphous glassy films at 120 °C and on molten samples at 200 °C by means of differential scanning calorimetry. Furthermore, the non-isothermal crystallization behavior of the copolyesters was investigated. It was observed that both crystallinity and crystallization rate of the PET^tBI copolyesters tend to decrease largely with the comonomeric content, except for the copolymer containing 5 mol% of ^tBI units, which crystallized faster than PET. Fiber X-ray diffraction patterns of the semicrystalline PET^tBI copolyesters proved that they adopt the same triclinic crystal structure as PET with the comonomeric units being excluded from the crystalline phase. Although PET^tBI copolyesters became brittle for higher contents in ^tBI, the tensile modulus and strength of PET were barely affected by copolymerization. The incorporation of ^tBI units slightly increased the permeability of PET, but copolymers containing up to 20 mol% of the comonomeric units were still able to present barrier properties.     

Multiobjective optimization of multiproduct batch plants scheduling under environmental and economic concerns

In batch process scheduling, production trade‐offs arise from the simultaneous consideration of different objectives. Economic goals are expressed in terms of plant profitability and productivity, whereas the environmental objectives are evaluated by means of metrics originated from the use of life cycle assessment methodology. This work illustrates a novel approach for decision making by using multiobjective optimization. In addition, different metrics are proposed to select a possible compromise based on the distance to a nonexistent utopian solution, whose objective function values are all optimal. Thus, this work provides a deeper insight into the influence of the metrics selection for both environmental and economic issues while considering the trade‐offs of adopting a particular schedule. The use of this approach is illustrated through its application to a case study related to a multiproduct acrylic fiber production plant, special attention is put to the influence of product changeovers. © 2010 American Institute of Chemical Engineers AIChE J, 57: 2766–2782, 2010     

Inactivation of Aerosolized Viruses in Continuous Air Flow with Axial Heating

Thermal inactivation of viruses has been studied in relevance to food sterilization, water purification, and other “non-aerosol” applications, in which heat treatment is applied for a relatively long time. No data are available on the inactivation of airborne viruses exposed to dry heat for a short time, although this is relevant to bio-defense and indoor air quality control. In this study, we investigated inactivation of aerosolized MS2 viruses in a continuous air flow chamber with axial heating resulted from exposures during ～ 0.1–1 s. For an airborne virion, the characteristic exposure temperature, T _e , was defined utilizing the air temperature profiles in the chamber. The tests were conducted at two air flow rates, Q, which allowed for establishing different thermal flow regimes and exposure time intervals. The experimentally determined inactivation factor, IF, was subjected to correction to account for the temperature profiles. At T _e up to ～ 90°C (Q = 18 L/min) and up to ～ 140°C (Q = 36 L/min), the loss of viral infectivity was relatively modest (≤ 10). However, IF increased exponentially as T _e rose from ～ 90°C to ～ 160°C (for 18 L/min) or from ～ 140°C to ～ 230°C (for 36 L/min). Under specific thermal exposure conditions (～ 170°C and ～ 250°C, respectively), IF exceeded ～ 2.4 × 10⁴ (～ 99.996% infectivity loss)—the maximum quantifiable in this study. The airborne MS2 virions exposed to hot air for < 1 s were found to have survived much higher temperatures than those subjected to thermal treatment in liquid for minutes or hours. The findings are significant for establishing limitations of the heat-based bioaerosol control methods.     

Optimization of a HS-SPME-GC-MS Procedure for Beer Volatile Profiling Using Response Surface Methodology: Application to Follow Aroma Stability of Beers Under Different Storage Conditions

The optimization of the main experimental variables, such as extraction temperature, volume of sample and the extraction time of an HS-SPME/GC-MS procedure, for profiling beer volatile analysis was evaluated using response surface methodology. A central composite circumscribed design was employed to study the effect of the experimental variables on the extraction of 28 representative volatile compounds of beer flavour profile. The parameters of the models were estimated by multiple linear regressions. The strongest influence in the volatile extraction yield was the volume of the sample (V) and the extraction temperature (T), with a positive and a negative effect, respectively. The performance characteristics of the optimised method were also determined, showing adequate linear ranges, repeatability, detection and quantification limits. The optimised methodology was applied to the same beer sample stored during 5?months at three different temperature conditions (4, 20 and 40?°C). Sampling was performed monthly, and the results showed that the concentration of most volatile compounds decreased during beer storage, although the rate of decrease was clearly higher at room temperature (20?°C) compared with refrigeration conditions (4?°C). Accelerated ageing conditions (40?°C) showed the most different volatile profile. Sensory analysis also revealed large differences in the overall quality of the samples, showing that even at room temperature the aroma profile of beer is greatly modified during its shelf life.     

Plants' entry and exit in Swedish municipalities

Plants' entry and exit behaviour in Swedish municipalities are studied within a fixed-effect, integer-valued autoregressive model. Based on eight industrial sectors, 1985–1993, and all municipalities, models are estimated by a generalized method of moment estimator. Influences on entry and exit are systematic and spatially as well as temporally variable. Responses to explanatory variables differ between sectors. Average income, local unemployment and higher education are found to be important determinants of both entry and exit across sectors. Received: August 1999/Accepted: January 2001     

Can a knowledge‐based cluster be created? The case of the Barcelona 22@ district*

The aim of this paper is to evaluate the local policy that has promoted the formation of a cluster of knowledge‐based activities in the city of Barcelona. After decades of economic and industrial stagnation in a district called Poblenou, in the year 2000 the City Council of Barcelona implemented a plan to renew the area's urban and economic structure. Under the development plan, knowledge‐based firms were encouraged to set up in the area and thus to create a cluster of advanced activities. This paper examines the success of this local policy and aims to determine whether cluster amenities have played a part in attracting knowledge‐based firms. First, we evaluated the cluster implementation via a ‘difference‐in‐differences’ analysis, comparing the increase in the percentage of knowledge‐based firms in this specific area with the increase of these firms in other local areas. Second, to determine whether the cluster amenities are an important element in attracting knowledge‐based activities, we perform a multivariate regression to see if cluster amenities (as valued by firms in a survey) do have an effect on the decision of knowledge‐intensive firms to locate in the district. El propósito de este artículo es evaluar la política local que ha favorecido la formación de un conglomerado de actividades basadas en conocimiento en la ciudad de Barcelona. Después de décadas de estancamiento económico e industrial en un distrito llamado Poblenou, el Ayuntamiento de Barcelona implementó en el año 2000 un plan para renovar la estructura urbana y económica de la zona. Siguiendo el plan de desarrollo, se animó a las empresas de actividades basadas en conocimiento a que se establecieran en este área, creando con ello un conglomerado de actividades avanzadas. Este artículo examina el éxito de esta política local e intenta determinar si los servicios de conglomerado han jugado un papel a la hora de atraer a empresas de actividades basadas en conocimiento. Primero, evaluamos la implementación del conglomerado por medio de un análisis de diferencia en diferencias, al comparar el aumento del porcentaje de empresas de actividades basadas en conocimiento en este área específica con el aumento de estas empresas en otras áreas locales. Segundo, para determinar si las amenidades de conglomerado son un elemento importante a la hora de atraer actividades basadas en conocimiento, realizamos una regresión multivariante para observar si las amenidades de conglomerado (así valoradas por las empresas en una encuesta) afectan a la decisión de las empresas basadas en conocimiento de ubicarse en este distrito.      

Intracellular Polysilicon Barcodes for Cell Tracking

During the past decade, diverse types of barcode have been designed in order to track living cells in vivo or in vitro, but none of them offer the possibility to follow an individual cell up to ten or more days. Using silicon microtechnologies a barcode sufficiently small to be introduced into a cell, yet visible and readily identifiable under an optical microscope, is designed. Cultured human macrophages are able to engulf the barcodes due to their phagocytic ability and their viability is not affected. The utility of the barcodes for cell tracking is demonstrated by following individual cells for up to ten days in culture and recording their locomotion. Interestingly, silicon microtechnology allows the mass production of reproducible codes at low cost with small features (bits) in the micrometer range that are additionally biocompatible.