Target tracking of autonomous robotic vehicles using range‐only measurements: a switched logic‐based control strategy

This paper considers the pursuing or target tracking problem where an autonomous robotic vehicle is required to move towards a maneuvering target using range‐only measurements. We propose a switched logic‐based control strategy to solve the pursuing problem that can be described as comprising a continuous cycle of two distinct phases: (1) the determination of the bearing, and (2) the steering control of the vehicle to follow the direction computed in the previous step while the range is decreasing. We provide guaranteed conditions under which the switched closed‐loop system achieves convergence of the relative distance error to a small neighborhood around zero. Simulation results are presented and discussed.Copyright © 2011 John Wiley & Sons, Ltd.     

Correlation Between Chemical Composition and Adherence of Cr and Co Coatings Deposited by Electric Arc

This paper presents the adhesive strength of FeCr and FeCoCr coatings produced by electric arc thermal spray process on carbon steel plates. Carbon steels are not resistant to corrosion and several methods are used in surface engineering to protect them from aggressive environments such as the marine one. The main objective of this work is the evaluation of the mechanical and metallurgical properties of coatings produced by thermal spray on carbon steel. Five chemical compositions were tested in order to give a large panel of possibility. Coatings were characterized by several methods to result in a screening of performance. The physical properties of coatings were also evaluated by adhesion quantification, using pull-off test, and microhardness measurement. The assessment of microstructural morphology by X-ray diffraction (XRD) and scanning electron microscopy (SEM) was made. The open circuit potential was monitored to evaluate the corrosion tendency. SEM results showed uniformity in the deposited layer and low amount of oxide and porosity. The adhesive strength of FeCoCr alloy coatings was higher than other coating conditions. In the immersion test, all sealed conditions presented high corrosion potential. Semi-quantitative phase calculation was performed by the Rietveld method using XRD. The presence of FeCr, FeCo, and austenite phases was determined. Based on the performed characterizations, the findings suggested that the FeCrCo deposition, with an epoxy sealing, is suitable to be used as an efficient coating of carbon steel in aggressive corrosive environments.     

Biocompatibility and cutaneous reactivity of cellulosic polysaccharide film in induced skin wounds in rats

The development of a skin substitute suitable for immediately performing the function of the lost dermis and epidermis could result in a positive impact on the treatment of patients with extensive skin lesions. A biopolymer film was applied to skin wounds to investigate the biocompatibility and cutaneous reaction and to test its activity as a mechanical barrier and conductor in the healing process. Forty Wistar rats of both sexes were used in the present study. Two excisions were performed in the dorsal part of the skin flaps. The polysaccharide film was applied over one of the incisions and other incision was washed with saline. The time spent for complete healing of both lesions was virtually the same in both groups, during 21 days of observation. The film remained attached to the bed of the exposed wound for an average period of 6 days. There were no statistically significant differences with regard to lesion measurement area at assessment times of 2nd, 7th and 14th postoperative days. At day 21, the scar area showed a significant difference (0.0229). After 40 days, all wounds were completely healed. No statistically significant differences were found between the histological parameters assessed in the experimental and control groups. The cellulosic polysaccharide film integrated well with the tissue showing high biocompatibility and low skin reactivity.     

Design and characterization of PNVCL-based nanofibers and evaluation of their potential applications as scaffolds for surface drug delivery of hydrophobic drugs

In this work, nanofiber scaffolds for surface drug delivery applications were obtained by electrospinning poly(N-vinylcaprolactam) (PNVCL) and its blends with poly(ε-caprolactone) and poly(N-vinylcaprolactam)-b-poly(ε-caprolactone). The process parameters to obtain smooth and beadless PNVCL fibers were optimized. The average fibers diameter was less than 1 μm, and it was determined by scanning electron microscopy analyses. Their affinity toward water was evaluated by measuring the contact angle with water. The ketoprofen release behavior from the fibers was analyzed using independent and model-dependent approaches. The low values of the release exponent (n < 0.5) obtained for 20 and 42 °C, indicating a Fickian diffusion mechanism for all formulations. Dissolution efficiencies (DEs) revealed the effect of polymer composition, methodology used in the electrospinning process, and temperature on the release rate of ketoprofen. PNVCL/poly(N-vinylcaprolactam)-b-poly(ε-caprolactone)-based nanofibers showed greater ability to control the in vitro release of ketoprofen, in view of reduced kinetic constant and DE, making this material promising system for controlling release of hydrophobic drugs. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48472.     

Characterization of novel thermoresponsive poly(butylene adipate-co-terephthalate)/poly(N-isopropylacrylamide) electrospun fibers

Polymer Bulletin - In this work, electrospun fibers of poly(butylene adipate-co-terephthalate) (PBAT) and poly(N-isopropylacrylamide) (PNIPAAm) blends, PBAT/PNIPAAm, with different mass ratios,...     

Personal multimedia services over a common home and access networking environment

This article presents a new end-to-end architecture model that will enable the deployment of a plethora of different multimedia services from diverse suppliers competitively coexisting over a common access and home networking environment. The model is focused on personal multimedia communication services and terminals. The proposed model is a segmentation of the end-to-end multimedia chain into several business segments. The interfaces among segments and functional entities inside each segment are identified and defined in the work. In order to study the impact level of the results achieved, a comparison with the approximation to NGN provided by current standardization bodies in the field (3GPP and TISPAN) is also included in the article. This comparison highlights the advantages of using this model as a solution to offer PMC services.     

Use of a new milk-clotting protease from Thermomucor indicae-seudaticae N31 as coagulant and changes during ripening of Prato cheese

Prato cheeses were manufactured using coagulant from Thermomucor indicae-seudaticae N31 or a commercial coagulant. Cheeses were characterised using the following analysis: yield; fat; acidity; moisture; ash; salt; pH; total nitrogen; total protein; NS-pH 4.6/NT*100; NS-TCA 12%/NT*100; casein electrophoresis; and RP-HPLC. The results were statistically analysed and revealed that the proteolytic indices were not significantly different throughout the 60 days of ripening of cheeses made with either coagulant. Even though there were some quantitative differences in the peptide profile of cheeses, the enzyme from T. indicae-seudaticae N31 was used in the production of good quality Prato cheese without having to change the established technological parameters of the process.     

Colour assays: An inside look into Alentejo traditional limewash paintings and coloured lime mortars

A series of colour assays were conducted taking into account old bibliographic recommendations and oral testimony regarding traditional lime painting technology from the Alentejo (South Portugal) region. The main objectives were: (a) the colorimetric analysis of paintings made with different limewash preparation methods; (b) the comparison between natural processed red and yellows ochre pigments (“home made” and from industrial origin) and synthetic iron oxides in different concentrations and lime proportions; (c) the evaluation of the colorimetric CIELAB coordinates during the lime carbonation process in coloured mortars and limewashes. The results shows that the evolution of L*, a*, and b* during the carbonation process is independent of pigment concentration and paint thickness but dependent of pigment composition and finishing technique (lime painting or coloured mortar). They also emphasize the importance of surface appearance attributes and its influence on the colorimetric parameters. © 2010 Wiley Periodicals, Inc. Col Res Appl, 36, 61–71, 2011     

Towards Test Purpose Generation from CTL Properties for Reactive Systems

This paper presents an approach for the generation of test purposes in the form of labelled transition systems from specifications of properties in CTL. The approach is aimed at adapting the model checking process, by extending search algorithms to perform further analysis so that examples and counter-examples can be extracted. An algorithm for the generation of test purposes through analysis over the examples and counter-examples is presented, along with a case study to show the correspondence between the CTL properties and the generated test purposes.