Bottleneck prediction and data-driven discrete-event simulation for a balanced manufacturing line

Bottleneck identification is a relevant tool for continuous optimization of production lines. In this work, we implement a data-driven discrete-event simulator (DDS) based on experimental distributions, obtained from real historical data. The DDS allows to analyse the behavior of a balanced manufacturing line at Bosch Thermotechnology, under different hypotheses. It shows that some scenarios perceived as likely to increase output may actually decrease production metrics, reveals the importance of line injection rates, and leads to the need for adequate real time bottleneck forecasting tools, which allow shift managers intervention in a useful time frame. Eleven prediction models are tested, where a random forest and a multi-layer perceptron attain the best performances (above 95% in all metrics). This data flow is operationalized through a micro-services pipeline which is briefly discussed.publishe

The obstacle problem at zero for the fractional p-Laplacian

In this paper we establish a multiplicity result for a class of unilateral, nonlinear, nonlocal problems with nonsmooth potential (variational-hemivariational inequalities), using the degree map of multivalued perturbations of fractional nonlinear operators of monotone type, the fact that the degree at a local minimizer of the corresponding Euler functional is equal one, and controlling the degree at small balls and at big balls.publishe

Sign changing solutions of a semilinear equation on Heisenberg group

Here, we studied an elliptic semilinear equation on a non-commutative manifold (the Heisenberg group) with a Dirichlet boundary condition. By using variational methods adapted to this setting, we prove that this problem possesses at least one positive solution and one sign changing solution for some values of the parameters

The Portuguese Manufacturing Sector during 2013-2016 after the Troika Austerity Measures

This work studies the effects of the Troika austerity measures on the Portuguese manufacturing firms in terms of efficiency scores. We adopted a non-parametric approach, which combines multidirectional efficiency analysis with other techniques, to examine two empirical hypotheses after the financial crisis and corresponding intervention of the Troika measures: (a) the performance of firms in the manufacturing sector has improved; (b) the manufacturing sector significantly acquired long-term debt but use it in an efficient way. Our results show that validation of the first hypothesis heavily depends on the firm size, and the second hypothesis is correct only with respect to long-term debt acquiring. In fact, some sectors have managed to maintain an acceptable level of efficiency, according to the circumstances, however, most of them have showed some inefficiency in the management of resources and less than 10% have been able to overcome the difficulties emerged after the intervention of the Troika. A common tool to overcome a crisis is the acquisition of long-term debts, which was done by 77% of firms; but with a lower gain, since it was the most efficient input resourced used. On the contrary, our results show that the number of employees and total assets are better leverage to maintain efficiency.publishe

Predictive maintenance on sensorized stamping presses by time series segmentation, anomaly detection, and classification algorithms

Sheet metal forming tools, like stamping presses, play an ubiquitous role in the manufacture of several products. With increasing requirements of quality and efficiency, ensuring maximum uptime of these tools is fundamental to marketplace competitiveness. Using anomaly detection and predictive maintenance techniques, it is possible to develop lower risk and more intelligent approaches to maintenance scheduling, however, industrial implementations of these methods remain scarce due to the difficulties of obtaining acceptable results in real-world scenarios, making applications of such techniques in stamping processes seldom found. In this work, we propose a combination of two distinct approaches: (a) time segmentation together with feature dimension reduction and anomaly detection; and (b) machine learning classification algorithms, for effective downtime prediction. The approach (a)+(b) allows for an improvement rate up to 22.971% of the macro F1-score, when compared to sole approach (b). A ROC AUC index of 96% is attained by using Randomized Decision Trees, being the best classifier of twelve tested. An use case with a decentralized predictive maintenance architecture for the downtime forecasting of a stamping press, which is a critical machine in the manufacturing facilities of Bosch Thermo Technology, is discussed.publishe

Towards an autonomous and intelligent airline operations control

Studies have estimated that irregular operations (flights affected by a disruption) can cost between 2% and 3% of the airline annual revenue and that a better recovery process could result in cost reductions of at least 20%. Even for small airlines this can represent millions of Euros. In this paper we propose a multi-agent system (MAS) whose members represent the roles, functionalities and competences existing in a typical Airline Operations Control Centre (AOCC), the airline entity responsible for managing the impact of irregular events on planned operations. This multiagent based system produces intelligent solutions in the sense that its outcomes are the result of an autonomous reaction and adaption to changes in the environment, solving partial problems simultaneously. We tested our MAS using real data from TAP Portuguese airline company and experimentally compared our system with solutions found by the human operators on TAP Portugal AOCC. A comparison was also made with a more traditional sequential approach that is the typical method followed by AOCCs when solving disruptions. Results from those comparisons show that it is possible to reduce costs and have a better integrated solution with the proposed system

Morphological analysis of Yarrowia lipolytica under stress conditions through image processing

Yarrowia lipolytica is an aerobic microrganism capable to produce important metabolites, has an intense secretory activity which drives efforts to be employed in industry (as a biocatalyst), in molecular biology and genetics studies. Dimorphism is refeered to fungi ability to growth in two distinct forms, usually as single oval cells os as a filament and to be reversible between each one. The cell shape is controlled by environmental factors and has been seeked by some authors [1,2,3]. Y. lipolytica has been considered an adequate model for dimorphism studies in yeasts since it has an efficient system for transformation and is easy to distinct between its morphological forms, on opposite to S. cerevisiae that do not produce true filaments and exhibits pseudohyphae growth under nitrogen limited conditions. Y. lipolytica has an hyphae diameter corresponding 60 to 100% of its single cell stage [4,5]. It is believed that Y. lipolytica dimorphism is related to defense mechanism from adverse conditions. The aim of this work resides on investigate morphological changes in Y. lipolytica under thermal and oxidative stress conditions. Yarrowia lipolytica (IMUFRJ 50682) was cultivated in YPD medium (glucose 2%, peptone 0.64%, yeast extract 1%) at 29oC and 160 rpm. Thermal stress experiments were carried employing a temperature shift (37oC / 1 h.). For oxidative ones, an addition of H2O2 was used to reach final concentration of 10mM. Both stress conditions were applied at exponential growth phase. Morphology was observed in a optic microscope (Axiolab, Zeiss) and cell characteristics were determined employing image processing analysis (Matlab v. 6.1, The Mathworks Inc.) and comparisons were carried on to a control system. A net increase around 22% on hyphae formation was detected as well as a significant increment in its length in relation to control system, when both thermal and oxidative stress was applied. The results herein obtained drives to consider a possible relationship between dimorphism and a cell response mechanism to stress conditions.Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq); Fundação para a Ciência e a Tecnologia (FCT); CAPES

Four solutions of an inhomogeneous elliptic equation with critical exponent and singular term

In this paper, we prove the existence of four nontrivial solutions of a elliptic equation with a Hardy singularity and show that at least one of them is sign changing. Our results extend some previous works on the literature, as Tarantello(1993), Kang-Deng(2005) and Hirano-Shioji(2005)

Galacto-oligosaccharides production during lactose hydrolysis by free Aspergillus oryzae β-galactosidase and immobilized on magnetic polysiloxane-polyvinyl alcohol

The synthesis of galacto-oligosaccharides (GOS) by the action of Aspergillus oryzae β-galactosidase free and immobilized on magnetic polysiloxane-polyvinyl alcohol (mPOS-PVA) was studied. A maximum GOS concentration of 26% (w/v) of total sugars was achieved at near 55% lactose conversion from 50%, w/v lactose solution at pH 4.5 and 40 °C. Trisaccharides accounted for more than 81% of the total GOS produced. GOS formation was not considerably affected by pH and temperature. The concentrations of glucose and galactose encountered near maximum GOS concentration greatly inhibited the reactions and reduced GOS yield. GOS formation was not affected by enzyme immobilization in the mPOS-PVA matrix, indicating the absence of diffusional limitations in the enzyme carrier. Furthermore, this water insoluble magnetic derivative was reutilized 10-times and retained about 84% of the initial activity. In addition, the kinetic parameters for various initial lactose concentrations were determined and compared for the free and immobilized enzyme.David F. M. Neri gratefully acknowledges support by the Programme Alpan, the European Union Programme of High Level Scholarships for Latin America (Scholarship No. E05D057787BR). Luiz B. Carvalho Jr. is recipient of a scholarship of the Brazilian National Research Council (CNPq)