Constructal design associated with genetic algorithm to minimize the maximum deflection of thin stiffened steel plates

This paper deals with the application of stochastic technique allied to the constructal design (CD) method and computational modeling for the optimization of composed plates reinforced by stiffeners. More specifically, it seeks to determine the optimal geometric configuration of the stiffened plate that minimizes its maximum deflection. For this purpose, a simply supported rectangular plate (with no stiffeners) was adopted as a reference. Then, a set of geometric configurations was proposed, through the application of CD method, by transforming a volume fraction (ϕ) of the reference plate into longitudinal and transverse stiffeners, maintaining the total volume, in-plane dimensions, boundary conditions, and loading. Regarding the optimization procedure, the genetic algorithm (GA) was chosen as the optimization method, and the geometric parameters considered as degrees of freedom were as follows: the number of longitudinal (N_ls) and transverse (N_ts) stiffeners; the thickness of the longitudinal (t_ls) and transverse (t_ts) stiffeners; and longitudinal and transverse stiffeners' heights ratio (h_ts/h_ls). Moreover, several values of ϕ were considered. Results indicated a great influence of the geometry on the mechanical behavior of the stiffened plates, as the optimal geometric configuration obtained here led to a reduction of over 98% in the maximum deflection in comparison with the reference plate.     

SmartSenior: Automatic Content Personalization Through Semi-supervised Learning

Wireless Personal Communications - The adaption of user interface (UI) promises to greatly enhance user experience (UX). This is more evident when we focus on elderly people. However, to date there...     

Nearest Neighbor Searches on the GPU

We introduce a GPU grid-based data structure for massively parallel nearest neighbor searches for dynamic point clouds. The implementation provides real-time performance and it is executed on GPU, both grid construction and nearest neighbors (approximate or exact) searches. This minimizes the memory transfer between device and system memories, improving overall performance. The proposed algorithm may be used across different applications with static and dynamic scenarios. Moreover, our data structure supports three-dimensional point clouds and given its dynamic nature, the user can change the data structure’s parameters at runtime. The same applies to the number of neighbors to be found. Performance comparisons were made against previous works, endorsing the benefits of our solution. Finally, we were able to develop a real-time Point-Based Rendering application for validation of the data structure. Its drawbacks and data distribution’s impact on performance were analysed and some directions for further investigation are given.     

Comparative evaluation of purity of green energetic material (ammonium dinitramide) depending on refining method

Although the solid propellant, ammonium dinitramide (ADN, NH₄N(NO₂)₂) is safe and thermally stable, it requires high purity for practical commercial applications. Even a small amount of impurities in ADN can create negative effects, including catalyst poisoning and thruster nozzle cloggings when it is used as a liquid propellant. Thus, we explored several purification processes for the precipitated ADN particles, such as repetition extraction, adsorption by activated carbons, and low-temperature extraction. These purifying methods help to improve the chemical purity as evaluated by FTIR, UV-vis, DSC, and IC analyses. Among the purification processes, adsorption was found to be the best method, showing a final purity of 99.768% based on relative quantification by ion chromatography.     

Baseline Influence on Single-Frequency GPS Precise Heading Estimation

When using the signal from the Global Positioning System (GPS) for precise estimation of a vehicle’s heading, the main challenge is finding the integer ambiguities in the carrier phase measurements. If the distance between the receiver’s antennas, also known as baseline length, is used in the process of solving that challenge, the resulting solution’s stability and precision can be enhanced, particularly for single-frequency L1 receivers. This paper presents a study of the overall influence of this baseline length in the precision and accuracy of the heading estimation, using raw measurements from two GPS single-frequency L1 receivers. Conclusions are presented based on the results from field trials for baselines up to 8 m.     

Molecular Markers for Assessing Must Varietal Origin

Wine quality and market value greatly depend on the grapevine varietal composition, which may be characteristic of specific regions. In order to defend the distinct regions, Denominations of Origin were defined to protect against fraudulent practices. In this study, we evaluated the efficiency of two microsatellite-based systems (microsatellite (SSR) and intermicrosatellite (ISSR)) for must varietal composition determination and their potential role in certification purposes. Eleven Vitis vinifera L. varieties from leaf and monovarietal must DNA samples were screened with six SSR and 14 ISSR primers to discriminate polymorphisms. Principal coordinates analysis was performed with DCENTER on the resultant data using unweighted pair group mathematical average and revealed that ISSRs markers were not suitable for certification procedures, whereas nuclear SSR markers presented a complete correspondence between leaf and must samples, demonstrating that they were adequate for traceability purposes.     

Infiltration of Portuguese cobblestone pavements – An exploratory assessment using a double-ring infiltrometer

The present study aims to evaluate small-scale infiltration losses of Portuguese cobblestone pavements. This type of pavement consists of rectangular hand-cut natural stones, mainly limestone, with different sizes and it is the most usual type of pavement for sidewalks and squares in Portuguese villages and cities. Portuguese cobblestone pavement can also be seen in several urban environments worldwide. A double-ring infiltrometer under constant and falling head was used for the field research work. Portuguese cobblestone pavements with small and coarse blocks were studied. The latter yield lower infiltration rates when compared to the former. The results show that, despite the block size, Portuguese cobblestone pavement contribute to reduce runoff, when compared with other impervious urban pavements.     

Chemical mechanical planarization of copper bumps on printed circuit board

This paper deals with the planarization of copper bumps to improve the bonding performance and reliability of printed circuit board (PCB) manufacturing to improve by using flip chip during the fabrication process of the PCB. Authors tried to develop a novel planarization process using polishing techniques before the continuous process at the PCB fabrication. An experiment was implemented by mechanical polishing (MP) using alumina abrasives mixed with deionizer water (DIW), and by chemical mechanical polishing (CMP) added with oxidizer of HF. CMP showed superior results to MP with mirror surface less than Ra 3nm and minimum step height deviation of 1um, resulting in high bonding performance and reliability. Therefore, CMP is a strong tool for reserving a sufficient margin in the PCB manufacture process.     

Supporting history of art with colorimetry: The paintings of Amadeo de Souza‐Cardoso

Colour is a key element in paintings but its quantitative analysis is seldom used as an interpretative element in the context of the history of art. Here, we show how this can be accomplished by measuring and analyzing the colours of the paintings of the influential Portuguese painter Amadeo de Souza‐Cardoso (1887‐1918). His last paintings have been classified by art historians as the most successful and are considered a chromatically homogeneous nucleus in his career. However, there are no quantitative data supporting these considerations. To access this we compared 24 of his paintings (1911‐17) using hyperspectral imaging data. From estimates of the number of colours that can be perceived in each painting we show that in the later works Amadeo has expanded the range of colours by including more hues and more levels of lightness. Moreover, the paintings dated from 1917 have similar chromatic distributions in colour space. This colorimetric analysis revealed to be an important tool that provides quantitative support to the hypothesis formulated by art historians.