A Combinatorial Optimization Technique for the Sequential Decomposition of Erosions and Dilations

This paper presents a general algorithm for the automatic proof that an erosion (respectively, dilation) has a sequential decomposition or not. If the decomposition exists, an optimum decomposition is presented. The algorithm is based on a branch and bound search, with pruning strategies and bounds based on algebraic and geometrical properties deduced formally. This technique generalizes classical results as Zhuang and Haralick, Xu, and Park and Chin, with equivalent or improved performance. Finally, theoretical analysis of the proposed algorithm and experimental results are presented.     

Predicting the ideological orientation during the Spanish 24M elections in Twitter using machine learning

Through the application of machine learning techniques, this paper aims to estimate the importance of messages with ideological load during the elections held in Spain on May 24th, 2015 posted by Twitter’s users, as well as other variables associated with the publication of these types of messages. Our study collected and analysed 24,900 tweets associated to two of the main trending topics’ hashtags (#24M and #Elections2015) used in the election day and build a predictive model to infer the ideological orientation for the messages which made use of these hashtags during Election Day. This approach allows us to classify the ideological orientation of all collected tweets, instead of only tweets that explicitly express their ideological or partisan preferences in the messages. Using the ideological orientation for all tweets predicted by our model, it was possible to identify how messages with a defined ideological load were pushed forward by users with leftist tendencies. We also observed a relationship between these messages and the partisan orientation of those who published them.

     

Radioluminescence study of calcium tungstate crystalline powders and ceramics

In this paper, the optical absorption and radioluminescence (RL) of polycrystalline ceramic and powder CaWO₄ are studied. The samples were synthesized via a solid‐state method. Differential thermal analysis and thermogravimetric (DTA/TG) measurements indicate a minimum temperature of 700°C for calcination of precursors. The crystalline phase of the samples of calcium tungstate was investigated by X‐ray diffraction (XRD). The RL of the crystal powder and ceramics are in agreement with that present in the literature for bulk single crystals, presenting a single emission band centered at 420 nm when irradiated with β‐rays. UV‐vis absorption spectroscopy shows that the maximum absorption band of the CaWO₄ sample is at around 400 nm, indicating the presence of mixed valence states of W⁵⁺ and W⁶⁺, associated with a possible breaking of structural symmetry caused by WO₄ tetrahedral distortion.     

Smooth interfaces for spectral element method for the solution of incompressible Newtonian fluid flow

A smoothing technique is developed to calculate the interface conditions of spectral element method for solving the incompressible Newtonian fluid flow. The first derivative at the interface of spectral elements is calculated by using only the adjacent subdomains. Numerical simulations of an incompressible laminar fluid flow through a planar channel and a 2:1 planar contraction channel are presented for various Reynolds numbers.

Laser-Sintered Bismuth Germanate Ceramics as Scintillator Devices

We have investigated the potential use of Bi₄Ge₃O₁₂ (BGO) laser-sintered ceramics in scintillator devices for radiation detection. Relevant results from the characterization made during the ceramic processing are presented, such as particle size analysis, X-ray diffraction studies, and thermal analysis. Furthermore, we have compared the microstructure, relative density, thermoluminescent (TL) emission, and transparency degree of ceramic bodies sintered by CO₂ laser heating with a reference set of ceramics sintered in an electrical furnace, and also with single crystals grown by the Czochralski technique. It was observed that the laser-sintered BGO presented a relative density of 98% (±2%), better pore shrinkage, larger grains, and light transmission intensity 1.5 times higher than the BGO ceramics sintered in a furnace. The TL curves of all samples irradiated with UV and β−rays presented peaks at 75°, 102°, and 143°C, and provided strong indication that the intergrain defects have the same nature of the bulk defects and do not contribute with new traps in the temperature range studied. The relative areas of the total TL emission after β irradiation were 6,0:4,4:1 for the reference ceramic, laser sintered ceramic, and single crystal, respectively. For UV irradiated samples, this relation was 7,1:4,7:1. From these results, we have concluded that laser-sintered ceramics have an amount of charge traps lower than the conventionally sintered BGO samples, thus having a higher radioluminescence yield.     

COMPARISON AMONG PI, DMC, QDMC, AND GPC ALGORITHMS IN THE CONTROL OF THE SPOUTED BED DRYER

This article presents comparative analysis between the classical PI (proportional-integral control) and MPC (model predictive control) techniques for a drying process on spouted beds. The on-line experimental setups were carried out in a laboratory-scale plant of a spouted bed dryer. The main objective was to optimize the plant operation by searching for the best control structure to be used in future scale enlargement. The major drawbacks encountered in this kind of system were high interactivity among variables, a malfunction as a result of calculated variables out of the operational window, and modeling mismatch. Despite the robustness of the operational PI, the control actions of this strategy did not overcome the variable interactions. The DMC (dynamic matrix control) and the QDMC (quadratic dynamic matrix control) algorithms performed satisfactorily over the major drawbacks. Special attention was given to the latter algorithm due to its ability to hold the variables under constrained oscillations. However, the best results were found for the adaptive GPC (generalized predictive control) algorithm whose actions prevailed over the modeling mismatch due to the strong nonlinear behavior intrinsic to the process. The main goal of the present work is to describe a procedure that can be standardized for other types of dryers and different scales. This is especially the case for the adaptive GPC, whose control structure is independent of the dryer nature and scale and whose implementation does not require previous identification procedures (self-tuning) and/or structural changes.     

Role of surface chemistry and morphology in the reactive adsorption of metal ions on acid modified dry bean pods (Phaseolus vulgaris L.) organic polymers

The present study aimed at verifying the acid surface modification of dry bean pods subjected to alkaline pretreatment using tannic acid, poly(acrylic acid), and poly(acrylamide‐co‐acrylic acid) and evaluate their performances as adsorbents in the metal ions removal. Factorial design was used as a tool to study the variables that affects the modification processes. The results showed that there was an increase in the adsorption capacity after acidic changes, mainly for the tannic acid, achieving 45% increasing of removal of all metal ions. The variable pH had negative significant effect in the modification with tannic acid. When the modifying agent was the poly(acrylic acid), the variable initial concentration presented a positive significant effect. That means more poly(acrylic acid) was immobilized in the surface of the bean pod, resulting in higher capacity of adsorption. Temperature was significant variable in the modification with poly(acrylamide‐co‐acrylic acid), resulting in a strongly negative effect. Analyses of material characterization showed that soluble lipid fraction was removed after the alkaline treatment. Although no morphological changes were observed, there was an improving in the availability of the adsorbents sites after chemical modification. Further, the material exhibited thermal stability up to about 300 °C. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45879.     

Effect of exogenous amylase on lactation performance of dairy cows fed a high-starch diet

Exogenous amylase supplementation can increase starch and fiber digestibility in lactating dairy cows. We evaluated the effect of exogenous amylase supplementation on diets with high starch concentration (32% of dry matter). Twenty-eight Holstein cows (171 ± 80 d in milk, 4 primiparous) received a standard diet for 14 d and then a treatment for 63 d, in a covariate-adjusted randomized block design with repeated measures over time. Treatments were amylase [0.5 g of Ronozyme RumiStar (DSM Nutritional Products, Basel, Switzerland) per kg of total mixed ration dry matter] or control. The diets contained (% of dry matter): 39.4% corn silage, 11.2% rehydrated and ensiled mature corn grain, and 11.7% finely ground mature corn. Amylase increased milk yield (32.3 vs. 33.0 kg/d) and reduced dry matter intake (20.7 vs. 19.7 kg/d), increasing feed efficiency (1.52 vs. 1.63). Amylase also increased milk lactose synthesis (1.49 vs. 1.56 kg/d) and plasma glucose concentration (59.3 vs. 68.6 mg/dL). Secretions of milk fat and protein did not differ. Although milk urea N did not differ, amylase reduced the concentration of urea N in blood, suggesting an increase in ruminal starch degradation. However, the total-tract apparent digestibility of starch (96.3% of intake) and neutral detergent fiber (44.4% of intake), ruminal fermentation profile, and microbial yield estimated by urinary allantoin excretion did not differ. Cows fed amylase sorted in favor of long feed particles and against short particles, had shorter chewing activity (780 vs. 699 min/d), and had fewer meals per day (11.5 vs. 9.7). Amylase improved the feed efficiency of lactating cows fed a high-starch diet; the enzyme increased milk yield and reduced intake.     

Evidence of Superposition between Grooving Abrasion and Rolling Abrasion

In ball-cratering wear tests, two abrasive wear modes are commonly observed, grooving abrasion and rolling abrasion, which act in distinct areas. Observing this tendency, the aim of this article is to discuss the characterization of an intermediate condition, in which the superposition of the grooving and the rolling abrasive wear modes is observed. This phenomenon is referred to as microrolling abrasion due to the following particular characteristic: the rolling abrasion was found to act on the grooving abrasion. Additionally, in a defined sliding distance range and normal force range, microrolling abrasion is qualitatively observed to be proportional to the sliding distance and inversely proportional to the normal force.     

Metallurgical evaluation of austenitic stainless surfacing welding on SAE 4130 steel

The objective of this study was to make a metallurgical evaluation of the austenitic stainless surfacing welding on the sealing area of the riser tubes made of SAE 4130 steel. The study was divided into two steps. The first step aims to determine the dilution rate and deposition rate for the minimum and maximum levels of heat input according to the welding procedure specification (WPS) for TIG and SMAW processes, followed by analysis and study on the Schaeffler diagram in order to identify the welding consumable best-suited to attend the established quality criteria. This study identified the electrode 312 as the filler material for the first layer, and the electrodes 309 and 308 for the second layer, both using the maximum heat input of the WPS and the SMAW process, with benefits to productivity. The second step has as its objective the validation of the empirical results found in the 1st step, with the execution of surfacing welds with two layers each, and the metallurgical characterization of the welded joints by mechanical testing and microstructural analysis by optical and electronic microscopy. The results of mechanical testing and microstructure were considered satisfactory, filling the adopted quality criteria. An austenitic-ferritic microstructure with delta ferrite content between 10 and 15% was observed for both layers of the surfacing. The electrode 312 assumed a prominent position in the application of the first layer of the surfacing weld on the SAE 4130 steel, according to its higher content of delta ferrite and chromium, avoiding hot cracks formation. For the second layer, both the 309 and 308 may be used. All welds were made with high heat input, ensuring increased productivity, without significant change in the physical and mechanical characteristics.