This work is concerned with a structural characterization of the diagnosability property in Timed Continuous Petri Nets (TCPNs) systems under infinite server semantics. Regarding this problem, three novel results are presented. The first one is the introduction of structural sufficient conditions for diagnosability in TCPNs, which are based on the concepts of relative degree, system distinguishability, and parameter identification. To this aim, the concept of a simple directed path from other works is extended to diagnosable directed paths. These new paths include attribution-places, pre-join-places and post-join-places, which allows to deal with multiple non-concurrent tokens-leak faults, and enlarging the class of systems that can be analyzed. Based on these structural conditions, a novel methodology to place a reduced number of sensors that guarantees the net diagnosability is proposed. Finally, a diagnoser based on a modified Differential Evolution algorithm is presented, which introduces individual searching sets in orthogonal spaces to diagnose (detect, locate, and identify) faults when an error is detected, avoiding the use of a bank of diagnosers of other approaches. The effectiveness and applicability of the main results are illustrated through an illustrative example.
In a total of 85 patients with laryngeal carcinoma, four markers of alcohol abuse were analyzed. The Ggt and VCM were disturbed. We found no correlation between tumor location, lymph node metastases, T stage, and histological grade. 相似文献
This investigation deals with the fatigue behavior of a group of thermoplastics fortified with discontinuous glass fibers dispersed by an injection molding process. The thermoplastics included nylon, polystyrene and polyethylene reinforced with short (1/8 in.) and long (1/2 in.) glass fibers. Several aspects of the fatigue behavior are included in the study. First, classical S–N curves were generated under fluctuating tension with R = 0.05 to show the loss of strength due to cyclic load application. Next, the extent of progressive fatigue damage was established by measuring the residual strength after cyclic loading. Finally, hypotheses pertaining to the fatigue mechanisms operative in all four materials were made based on microscopic examinations of sections removed from fatiguedamaged specimens. 相似文献
The Baja California Peninsula is one of the richest regions of seaweed resources in México. The objective of this study was to determine the chemical composition of some marine algae species of Baja California Sur, with an economical potential due to their abundance and distribution, and to promote their use as food for human consumption and animal feeding. The algae studied were Green (Ulva spp., Enteromorpha intestinalis, Caulerpa sertularoides, Bryopsis hypnoides), Red (Laurencia johnstonii, Spyridia filamentosa, Hypnea valentiae) and Brown (Sargassum herporizum, S. sinicola, Padina durvillaei, Hydroclathrus clathrathus, Colpomenia sinuosa). The algae were dried and ground before analysis. In general, the results showed that algae had a protein level less than 11%, except L. johnstonii with 18% and low energy content. The ether extract content was lower than 1%. However, the algae were a good source of carbohydrates and inorganic matter. 相似文献
Nowadays it is known that the thermomechanical schedules applied during hot rolling of flat products provide the steel with improved mechanical properties.In this work an optimisation tool,OptiLam (OptiLam v.1),based on a predictive software and capable of generating optimised rolling schedules to obtain the desired mechanical properties in the final product is described.OptiLam includes some well-known metallurgical models which predict microstructural evolution during hot rolling and the transformation austenite/ferrite during the cooling.Furthermore,an optimisation algorithm,which is based on the gradient method,has been added,in order to design thermomechanical sequences when a specific final grain size is desired.OptiLam has been used to optimise rolling parameters,such as strain and temperature.Here,some of the results of the software validation performed by means of hot torsion tests are presented,showing also the functionality of the tool.Finally,the application of classical optimisation models,based on the gradient method,to hot rolling operations,is also discussed. 相似文献
The stability analysis of a vision-based control strategy for a quad rotorcraft UAV is addressed. In the present application, the imaging sensing system provides the required states for performing autonomous navigation missions, however, it introduces latencies and time-delays from the time of capture to the time when measurements are available. To overcome this issue, a hierarchical controller is designed considering a time-scale separation between fast and slow dynamics. The dynamics of the fast-time system are stabilized using classical proportional derivative controllers. Additionally, delay frequency and time domain techniques are explored to design a controller for the slow-time system. Simulations and experimental results consisting on a vision-based road following task are presented. 相似文献
Lignocellulosic–plastic composites are materials widely used in the construction industry; however, their mechanical performance and durability constitutes a serious issue due to the nature of the lignocellulosic component which makes it prone to biological degradation. This article gives account of the protective performance of a novel eco-friendly solvent based coating obtained from recycled expanded polystyrene dissolved with Limonene, and three different coating systems used generally for outside wood protection, applied on a Kraft paper for potential structural use. Three aspects were evaluated, namely coating interaction with the lignocellulosic substrate, water absorption and resistance to Nasutitermes corniger termite attack. Scanning electron microscopy revealed two types of interaction namely—adsorption and absorption—of the coatings systems in the fibrous structure. Coating absorption revealed better protection for water absorptiveness of the paper structure. After biotic exposure, sample weight loss and damaged structure were observed, highlighting the aggressiveness of this type of termites which attack any kind of material studied here, in order to reach their food source. 相似文献