A linear optimization approach to the combined production planning model

Two fundamental processes usually arise in the production planning of many industries. The first one consists of deciding how many final products of each type have to be produced in each period of a planning horizon, the well-known lot sizing problem. The other process consists of cutting raw materials in stock in order to produce smaller parts used in the assembly of final products, the well-studied cutting stock problem. In this paper the decision variables of these two problems are dependent of each other in order to obtain a global optimum solution. Setups that are typically present in lot sizing problems are relaxed together with integer frequencies of cutting patterns in the cutting problem. Therefore, a large scale linear optimizations problem arises, which is exactly solved by a column generated technique. It is worth noting that this new combined problem still takes the trade-off between storage costs (for final products and the parts) and trim losses (in the cutting process). We present some sets of computational tests, analyzed over three different scenarios. These results show that, by combining the problems and using an exact method, it is possible to obtain significant gains when compared to the usual industrial practice, which solve them in sequence.     

Ageing of brazilwood dye in wool – a chromatographic and spectrometric study

Brazilwood was used in this work to dye wool mordanted with different amounts of copper(II) sulfate, alum and iron(II) sulfate. Two different dyeing methods were used: premordanting (MD) and simultaneous mordanting (M+D) procedures. In order to evaluate the influence of the mordant ion in the brazilein chromophore photodegradation, samples were subjected to artificial light ageing. Color measurements were made and, for the first time, LC-DAD-ESI-MS was used for chromophore analysis of the dyed fibers before and after light exposure. Mordant ion quantification was done after fiber acid digestion, by inductively coupled plasma-optical emission spectroscopy (ICP-OES) and flame atomic absorption spectroscopy (FAAS). Mordant metal ion, mordant bath concentration and dyeing procedure were found to have strong influence in the wool fiber hues. Color variation was more pronounced in the alum dyed samples. Overall, mordant quantification showed that the amount of metal ions found in the fibers is very small when compared to the original concentrations of the dyeing bath, being Cu the ion with greater affinity for the wool fibers. MD dyeing procedure yielded fibers with larger amounts of mordant metal ions and higher chromophore peak areas. Higher amounts of brazilein were extracted from wool mordanted with copper(II) sulfate. Finally, chromatographic analysis of the brazilwood dyed samples before and after light exposure resulted in the detection of Type C compound as an outcome of the photodegradation process.     

Diversified production of red figured pottery in Apulia (Southern Italy) in the late period

Late Apulian red figured pottery [1] from Egnatia (Fasano, Brindisi, Italy) was studied in order to widen the view on this ceramic class in Southern Italy. Inductively Coupled Plasma Mass Spectroscopy (ICP-MS) provided the samples elemental composition that allowed to make provenance hypotheses. Optical Microscopy (OM) and Scanning Electron Microscopy (SEM) with Energy Dispersive Spectrometry (EDS), supplied information about the minero-petrographic features of the objects to better understand their production technology. The set of results highlighted the contemporary presence in the Apulian land in the late 4th century BC of both local and imported finds and showed the existence of two different kinds of local production, the “classic” Attic and a peculiar one, characterized by the application of an engobe layer before the black gloss. Our previous studies resulted in the discovery that an engobe layer, with similar chemical and minero-petrographic characteristics, was present in finds from another site in central Apulia (Monte Sannace). So the discovery of red engobe on fragments from Egnatia, proves that its use was not an isolated occurrence, but was quite common in the production of red figured in Apulia during the Late period, appearing as a peculiar technological mark of Apulian potters.     

Misconceptions About Sound Among Engineering Students

Our first objective was to detect misconceptions about the microscopic nature of sound among senior university students enrolled in different engineering programmes (from chemistry to telecommunications). We sought to determine how these misconceptions are expressed (qualitative aspect) and, only very secondarily, to gain a general idea of the extent to which they are held (quantitative aspect). Our second objective was to explore other misconceptions about wave aspects of sound. We have also considered the degree of consistency in the model of sound used by each student. Forty students answered a questionnaire including open-ended questions. Based on their free, spontaneous answers, the main results were as follows: a large majority of students answered most of the questions regarding the microscopic model of sound according to the scientifically accepted model; however, only a small number answered consistently. The main model misconception found was the notion that sound is propagated through the travelling of air particles, even in solids. Misconceptions and mental-model inconsistencies tended to depend on the engineering programme in which the student was enrolled. However, students in general were inconsistent also in applying their model of sound to individual sound properties. The main conclusion is that our students have not truly internalised the scientifically accepted model that they have allegedly learnt. This implies a need to design learning activities that take these findings into account in order to be truly efficient.     

The Devil in the Detail: Contradictory national requirements and Bologna master degrees

This article compares the national-level requirements for master degree provision in England, Denmark and Portugal following the implementation of the Bologna Process, and ponders upon the reconcilability of these requirements in cross-national initiatives (e.g. joint degrees). In all three countries, master degrees have to comply with the national qualification frameworks, which have been verified against the Framework for Qualifications of the European Higher Education Area. Other regulations apply, however. In Denmark and Portugal, higher education degrees are tightly regulated by legislation, while the Academic Infrastructure developed by the Quality Assurance Agency in the UK acts as a broad reference for degree design, giving English institutions a high degree of freedom. Findings reveal the existence of contradictory requirements which have arisen further to policy adaptations, made possible by the non-legally binding character of Bologna and its loose policy mechanisms.     

Revisiting Quality Television: Audience Perceptions

ABSTRACT

This article analyzes what the audience understands by the concept of quality as applied to television channels. This research also examines the influence of the perceived quality of the different programs broadcasted by a channel on the perceived quality of the whole channel. The empirical part is based on the answers provided by a sample of 405 respondents in Spain. The factors found to be associated with the idea of quality television by the audience are somewhat different depending on the method used to assess it, which points to the existence of social desirability bias when asking directly about it. Notwithstanding these differences, entertainment is the characteristic that the audience most consistently associates with the concept of quality in television channels. The results also show that news programs, movies and magazines, and talk shows are the genres with a greatest influence on the assessment of the quality of a television channel by the audience.     

Metalinguistic skills in children: what develops?

Abstract

The aim of this study is to test developmental changes in metalinguistic skills in primary school children, using the distinction proposed by Bialystock (1986) between «analyzed knowledge» and «executive control», as two components of metalinguistic awareness involved in different tasks. 60 first, second and third grade children were individually interviewed on two tasks. In the first task (guided word substitution) children were asked to substitute an underlined word with five alternatives, thus producing new sentences to be judged on their semantic and/or morpho-syntactical acceptability. In the second task (free word substitution), children have to find out the word that can be cancelled and substituted with a new one. In both tasks children have to express an acceptability judgement, giving reasons for it. Each subject receives two scores for each task. Results from two-way Anova show that the «control» component does not change much, while the «analyzed knowledge» changes significantly, although also third grade children are more aware of semantic than of morpho-syntactic features of language.