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  • Author: Zoltán Szabó x
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LPV design of fault-tolerant control for road vehicles

The aim of the paper is to present a supervisory decentralized architecture for the design and development of reconfigurable and fault-tolerant control systems in road vehicles. The performance specifications are guaranteed by local controllers, while the coordination of these components is provided by a supervisor. Since the monitoring components and FDI filters provide the supervisor with information about the various vehicle maneuvers and the different fault operations, it is able to make decisions about necessary interventions into the vehicle motions and guarantee reconfigurable and fault-tolerant operation of the vehicle. The design of the proposed reconfigurable and fault-tolerant control is based on an LPV method that uses monitored scheduling variables during the operation of the vehicle.

Abstract

Experimental, also known as experience marketing, interactivity, gamification. These three terms became very popular in the past years, by 2018, they set up the the main guidelines of marketing trends but the terms are not all novel. The philosophers, psychologists, sociologist and marketing specialists have been dealing with the impacts of experiences and reactions on human nature.

This study is going to try to explore the relationship and relationships between the three terms more deeply. Before the final conclusions were drawn, three things had to be studied: what is experience, what interactivity means and what is the meaning of gamification. At the end of the article, a comprehensive picture the 3 main phenomenon emerges. The aforementioned terms often collapse, therefore sometimes it is hard to draw the real reports from the many literatures. To find out the answer, psychology had been called for help, which provided a precise point of reference for information processing.

Abstract

There are several methods of automotive diagnostics used in services to detect a large variety of faults and damages of various parts of engines of internal combustion. Undoubtedly, they are effective, but they are simply unable to find all types of mechanical faults occurring during the operation. This is the reason why authors of this paper tried to use a special tool, which has been proven for years for detecting faults of rolling element bearing in rotating machinery. During their research, the authors tried to find valuable results by measuring vibration of various parts of engines. Three items were tested, a Diesel engine and two Otto motors. A large number of measurements have been taken at various speed, at different points, in different directions, with different parameter setup, etc. However, there was one setup which has been applied to all three engines. It is the measurement setup of vibration velocity, in the frequency range of 2 Hz-300 Hz. Valuable consequences have been found regarding the clogging of the air filters and the exhaust systems. As a conclusion the authors expressed their opinion, that, apart from the traditional diagnostic methods used in services, vibration measurements can also be useful, especially for detecting faults of rolling element bearings.

Abstract

Antimicrobial peptides are natural substances that have played a role in the development of the adaptive immune system, and are currently involved in the prevention of infections, through their direct antimicrobial and immunomodulatory properties. While the amino acid composition and spatial structure vary, most antibacterial peptides have a positive surface charge, which allows them to bind to the negative bacterial membranes. Buforin II is a widely studied antimicrobial peptide first obtained through the structural modification of buforin I, a peptide isolated from Bufo gargarizans. The peptide showed significant antibacterial activity against Gram-positive and Gram-negative bacterial strains. The mechanism of action of buforin II differs from that of other antimicrobial peptides, as it binds directly to bacterial DNA and RNA. The aim of our study was to obtain recombinant buforin II with a ubiquitin fusion partner, through heterologous expression in Escherichia coli Rosetta™ (DE3)pLysS cells, using a laboratory scale biore-actor. The incubation of expression host cells in a bioreactor allowed the constant monitoring and control of the process parameters, leading to high biomass levels and an increased production rate of the peptide. The parameters used during incubation were: 37°C, pH=6.9 and dissolved oxygen level above 40%. Purification of the recombinant protein was accomplished by affinity chromatography using a Ni-chelate solid phase to which the 10xHistag of our construct showed affinity. Method optimisation consisted in the use of gradient and linear elution, of which the latter was found to be more effective. Digestion of the fusion partner from the target peptide was performed with ubiquitin carboxyl-terminal hydrolase enzyme. The expression and purification protocols developed in our experiment allow the production of a significant amount of buforin II, allowing its use for further research. Furthermore, the presented methods could be suitable for industrial production of the recombinant peptide..

Abstract

The chiral separation of three racemic immunomodulatory drugs, thalidomide, pomalidomide and lenalidomide was studied, using three cyclodextrin bonded stationary phases (β-, hydroxypropyl-β- and carboxymethyl-β-CD) in reversed-phase and polar organic mode. In polar organic mode, using acetonitrile and methanol, no chiral separation was observed. In reversed-phase mode pomalidomide showed chiral interactions with all selectors, while lenalidomide showed no chiral interactions with any of the cyclodextrins employed. Thalidomide showed chiral interactions with β-and carboxymethyl-β-CD, only. Based on these observations it can be concluded that the oxo group at position two is necessary for chiral recognition, while the aromatic primary amine group enhances it. Orthogonal experimental design was used to investigate the effect of the eluent composition, flow rate, and the column temperature on chiral separation. Concentration of the organic modifier was the most important factor among the investigated three variables showing high impact on the chiral separations. In the case of thalidomide optimized parameters (β-cyclodextrin-based stationary phase, 0.1% acetic acid/acetonitrile 95/5 (v/v), 5 °C column temperature, 0.6 ml/min flow rate) resulted in a resolution of 1.68 ± 0.02 between enantiomers. For pomalidomide, this value was 2.70 ± 0.02, under the circumstances as follows: β-cyclodextrin-based stationary phase, 0.1% acetic acid/acetonitrile 90/10 (v/v), 15 °C column temperature and 0.8 mL/min flow rate. Utilizing the experimental conditions employed on an LC-MS/MS system, concentrations as low as 2 ng/mL could be determined from mouse plasma for both substances. Elution sequences were determined with enantiopure standards and in both cases the R-enantiomers eluted first. The methods developed are suitable for the chiral separation of the abovementioned compounds and are sound starting points for bioanalytical method development.

Abstract

Objectives. Evaluation of the characteristics of sleep apnea (SA) in patients hospitalized with acute heart failure, considering that undiagnosed SA could contribute to early rehospitalization. Methods. 56 consecutive patients (13 women, 43 men, mean age 63.12 years) with acute heart failure, in stable condition, underwent nocturnal polygraphy before hospital discharge. The type and severity of SA was determined. Besides descriptive statistics, correlations between the severity of SA and clinical and paraclinical characteristics were also analyzed (t-test, chi-square test, significancy at alpha < 0.05). Results. 12 (21.4%) subjects were free of SA (AHI - apnea-hipopnea index <5/h), 15 (26.7%) had mild SA (AHI=5-14/h), 17 (30.3%) had moderate SA (AHI 15-30/h), and 12 (21.4 %) had severe SA (AHI>30/h). The apnea was predominantly obstructive (32 cases vs. 12 with central SA). Comparing the patients with mild or no SA with those with severe SA, we did not find statistically significant correlations (p>0.05) between the severity of SA and the majority of main clinical and paraclinical characteristics - age, sex, BMI, cardiac substrates of heart failure, comorbidities. Paradoxically, arterial hypertension (p=0.028) and atrial fibrillation (p=0.041) were significantly more prevalent in the group with mild or no SA. Conclusions. Before discharge, in the majority of patients hospitalized with acute heart failure moderate and severe SA is present, and is not related to the majority of patient related factors. Finding of significant SA in this setting is important, because its therapy could play an important role in preventing readmissions and improving prognosis.

Abstract

Objective: The study aimed at obtaining and characterizing levofloxacin-loaded, poly(ε-caprolactone) electrospun nanofiber formulations to be used as antibacterial wound dressings. Methods: Drug-loaded nanofibers were obtained by the electrospinning process and their morphology was determined using scanning electron microscopy. Structural analysis of the prepared nanofibers was carried out using differential scanning calorimetry and dissolution testing was performed in order to determine drug release. Results: Both nanofiberous formulations (containing 20 % and 50 % w/w levofloxacin) showed dimensions in the range of few hundred nanometers. Thermograms indicated that the formulation containing 20% levofloxacin was totally amorphized, showing a rapid release of the active, in 20 minutes. Conclusions: The poly(ε-caprolactone)-based electrospun nanofibers, containing levofloxacin presented suitable characteristics for obtaining potential antibacterial wound dressings.

Abstract

In type A aortic dissection (AoD) an early and accurate diagnosis is essential to improve survival, by applying urgent surgical repair. 3D transthoracic echocardiography (3D-TTE), an advanced noninvasive imaging technique, could offer a comprehensive evaluation of the ascending aorta and aortic arch in this regard. Both modalities of real-time 3D imaging – live 3D and full-volume aquisition – proved to be useful in evaluating the localization and extent of AoD. Our case illustrates the utility of 3D-TTE in the complex assessment AoD. By providing the proper anatomical dataset, 3D-TTE could facilitate considerably the diagnosis of type A AoD.

Abstract

The forest area in Hungary has increased during the last century from 1.1 to 2.0 million ha. The European Union supports further afforestation so roughly 15 -18 000 hectares are being planted each year, mostly on the Hungarian Great Plain. Water uptake of forests from groundwater can be significant in shallow groundwater areas of the Hungarian Great Plain especially in drought periods. Therefore forests can induce water table depression and subsurface salt accumulation above saline water table in areas with a negative water balance.

The impact of forests is examined by a systematic study on the Hungarian Great Plain., An oak forest and a pasture groundwater uptake and salt accumulation effect were compared at the stand scale. Under the forest the water table levels were roughly 0.5 m lower than under the pasture, and the groundwater uptake of the oak plot was more than twice as great. Larger forest groundwater use is not followed by a higher salt uptake. Therefore slight salt accumulation was measured both in the soil and also in the groundwater. Higher groundwater uptake may cause more significant salt accumulation under pronounced drought conditions of a warmer climate.

Abstract

A multi-level reconfiguration framework is proposed for fault tolerant control of over-actuated aerial vehicles, where the levels indicate how much authority is given to the reconfiguration task. On the lowest, first level the fault is accommodated by modifying only the actuator/sensor configuration, so the fault remains hidden from the baseline controller. A dynamic reallocation scheme is applied on this level. The allocation mechanism exploits the actuator/sensor redundancy available on the aircraft. When the fault cannot be managed at the actuator/sensor level, the reconfiguration process has access to the baseline controller. Based on the LPV control framework, this is done by introducing fault-specific scheduling parameters. The baseline controller is designed to provide an acceptable performance level along all fault scenarios coded in these scheduling variables. The decision on which reconfiguration level has to be initiated in response to a fault is determined by a supervisor unit. The method is demonstrated on a full six-degrees-of-freedom nonlinear simulation model of the GTM UAV.