High resolution approach for the localization of buried defects in the multi-frequency eddy current imaging of metallic structures

A high resolution approach is proposed to quantitatively estimate the depth of defects buried in planar metallic structures. This approach associates a multiple signal characterization (MUSIC) algorithm with an original eddy current imager. The interactions of the eddy currents and the defects are modelled by a set of virtual magnetic sources propagating in a spherical manner up to the surface of the structure. The defect localization is carried out using the MUSIC algorithm, applied to the multi-frequency observation of the magnetic field distribution at the surface of the structure. Accurate results obtained on simulated and experimental data relative to defects buried down to 5.4 mm in an aluminium layered structure validate the approach.     

Thermal runaway analysis of a three-phase reactor for LCO hydrotreatment

Safety is a high-priority topic for the chemical industry to minimize the frequency and severity of accidents while keeping the productivity and quality of the production. The processes that may undergo thermal runaways due to exothermic reactions are at the heart of the risks of accidents. The study of such highly reactive systems is essential to achieve a safe and productive operation of existing processes and to ensure inherently safe new designs. It is well known that the stationary analysis with the van Heerden criterion must be satisfied, however, this is not sufficient to ensure reactor stability. Only dynamic analysis can provide an accurate answer concerning the safe operation of the reactor. Most of the reported stability studies are carried out for relatively simple systems (pseudo-homogeneous models, simple reaction schemes). This work presents the dynamic thermal stability study of a refining process (hydrotreatment of light cycle oils) carried out with real gasoils at industrial operating conditions. A 1D dynamic model that accurately represents the reactive system (gas–liquid–solid) was developed and validated with experimental pilot plant data. This mathematical model was used to perform the thermal stability analysis of the dynamic system using a perturbation method. The effect of the variation of the heat transfer coefficient on the thermal stability is presented. The spectral analysis of the eigenvalues indicating the stable/unstable behavior of the reactive system was compared with dynamic simulations. An excellent agreement was found between the simulations and the stability analysis. The case of oscillating behavior is also described. The frequencies of oscillation determined by the stability analysis are compared to the frequencies calculated by Fourier transform applied to the simulated signal. The reactor behavior and the oscillations features are accurately predicted with this stability analysis method.     

Cobalt and Nickel Nanopillars on Aluminium Substrates by Direct Current Electrodeposition Process

A fast and cost-effective technique is applied for fabricating cobalt and nickel nanopillars on aluminium substrates. By applying an electrochemical process, the aluminium oxide barrier layer is removed from the pore bottom tips of nanoporous anodic alumina templates. So, cobalt and nickel nanopillars are fabricated into these templates by DC electrodeposition. The resulting nanostructure remains on the aluminium substrate. In this way, this method could be used to fabricate a wide range of nanostructures which could be integrated in new nanodevices.     

Multi-Attack Intrusion Detection System for Software-Defined Internet of Things Network

Currently, the Internet of Things (IoT) is revolutionizing communication technology by facilitating the sharing of information between different physical devices connected to a network. To improve control, customization, flexibility, and reduce network maintenance costs, a new Software-Defined Network (SDN) technology must be used in this infrastructure. Despite the various advantages of combining SDN and IoT, this environment is more vulnerable to various attacks due to the centralization of control. Most methods to ensure IoT security are designed to detect Distributed Denial-of-Service (DDoS) attacks, but they often lack mechanisms to mitigate their severity. This paper proposes a Multi-Attack Intrusion Detection System (MAIDS) for Software-Defined IoT Networks (SDN-IoT). The proposed scheme uses two machine-learning algorithms to improve detection efficiency and provide a mechanism to prevent false alarms. First, a comparative analysis of the most commonly used machine-learning algorithms to secure the SDN was performed on two datasets: the Network Security Laboratory Knowledge Discovery in Databases (NSL-KDD) and the Canadian Institute for Cybersecurity Intrusion Detection Systems (CICIDS2017), to select the most suitable algorithms for the proposed scheme and for securing SDN-IoT systems. The algorithms evaluated include Extreme Gradient Boosting (XGBoost), K-Nearest Neighbor (KNN), Random Forest (RF), Support Vector Machine (SVM), and Logistic Regression (LR). Second, an algorithm for selecting the best dataset for machine learning in Intrusion Detection Systems (IDS) was developed to enable effective comparison between the datasets used in the development of the security scheme. The results showed that XGBoost and RF are the best algorithms to ensure the security of SDN-IoT and to be applied in the proposed security system, with average accuracies of 99.88% and 99.89%, respectively. Furthermore, the proposed security scheme reduced the false alarm rate by 33.23%, which is a significant improvement over prevalent schemes. Finally, tests of the algorithm for dataset selection showed that the rates of false positives and false negatives were reduced when the XGBoost and RF algorithms were trained on the CICIDS2017 dataset, making it the best for IDS compared to the NSL-KDD dataset.     

Ultraviolet optical and microstructural properties of MgF2 and LaF3 coatings deposited by ion-beam sputtering and boat and electron-beam evaporation

Single layers of MgF2 and LaF3 were deposited upon superpolished fused-silica and CaF2 substrates by ion-beam sputtering (IBS) as well as by boat and electron beam (e-beam) evaporation and were characterized by a variety of complementary analytical techniques. Besides undergoing photometric and ellipsometric inspection, the samples were investigated at 193 and 633 nm by an optical scatter measurement facility. The structural properties were assessed with atomic-force microscopy, x-ray diffraction, TEM techniques that involved conventional thinning methods for the layers. For measurement of mechanical stress in the coatings, special silicon substrates were coated and analyzed. The dispersion behavior of both deposition materials, which was determined on the basis of various independent photometric measurements and data reduction techniques, is in good agreement with that published in the literature and with the bulk properties of the materials. The refractive indices of the MgF2 coatings ranged from 1.415 to 1.440 for the wavelength of the ArF excimer laser (193 nm) and from 1.435 to 1.465 for the wavelength of the F2 excimer laser (157 nm). For single layers of LaF3 the refractive indices extended from 1.67 to 1.70 at 193 nm to approximately 1.80 at 157 nm. The IBS process achieves the best homogeneity and the lowest surface roughness values (close to 1 nm(rms)) of the processes compared in the joint experiment. In contrast to MgF2 boat and e-beam evaporated coatings, which exhibit tensile mechanical stress ranging from 300 to 400 MPa, IBS coatings exhibit high compressive stress of as much as 910 MPa. A similar tendency was found for coating stress in LaF3 single layers. Experimental results are discussed with respect to the microstructural and compositional properties as well as to the surface topography of the coatings.     

Anesthesia in surgery for epilepsy

OBJECTIVES: To evaluate the efficacy of general anesthesia during epileptic surgery. MATERIAL AND METHODS: A retrospective study of 64 patients who received general anesthesia during epileptic surgery. In the preoperative period, anticonvulsive medication was adjusted in accordance with plasma levels and withdrawn entirely 8 hours before surgery. After premedication with droperidol and fentanyl, a balanced anesthetic technique was applied, based on pentothal, pancuronium (or vecuronium), fentanyl, N2O and isoflurane. Continuous monitoring of ECG, arterial blood pressure, pulse oximetry, ET CO2 and neuromuscular function. Isoflurane was stopped for 10 min after the opening of the duramadre so that ECoG could be recorded and methohexital or propofol was given in some cases in order to activate the epileptogenic focus. Muscular relaxation was restored intraoperatively following the study of somatosensory evoked potentials. Immediate and later complications related to anesthesia or surgery were recorded. RESULTS: The surgical procedure performed in most cases was temporal or frontal resection, with a mean duration for anesthesia of 377 +/- 50 min and for surgery of 318 +/- 50 min. Only one patient received local anesthesia and no hemodynamic changes were observed. Perioperative complications were cerebral edema (4 cases), arrhythmia (2 cases) and bronchospasm (1 case). Postoperative complications were as follows: 3 of 9 patients undergoing callosotomy required mechanical ventilation for 24 hours, 4 patients experienced language alterations, 3 wounds were infected, 2 cases of hemiplegia were observed, 1 status epilepticus occurred after administration of propofol and there was 1 case of respiratory distress. Anticonvulsive medication was given parenterally after surgery. CONCLUSIONS: General anesthesia is a safe and effective method for epileptic surgery, with local anesthesia providing additional sedation for isolated cases. Appropriate treatment requires an understanding of the pharmacokinetics and pharmacodynamics of the drugs used, as well as knowledge of the condition and the anticonvulsive medications used.     

Bartonella henselae infection in immunocompetent patients: cat scratch disease

BACKGROUND: Cat scratch disease, whose etiologic agent is Bartonella henselae, is a benign disease in immunocompetent subjects, characterized by lymphadenopathy of prolonged course and occasional involvement of other organs such as liver, spleen, central nervous system, eye and lung. In immunocompromised patients, the infection is bacteremic and disseminated. AIM: To report Chilean cases of cat scratch disease. PATIENTS AND METHODS: Ten children (seven male, aged between 6 and 13 years old) with histologically or serologically confirmed cat scratch disease are reported. RESULTS: Lymphadenopathy location was pre auricular in four cases, axillary in two, inguinal in two and epitrochlear in two. Three children had fever over 39 degrees C and two had a parinaud syndrome. Nine children had a history of cat scratch and one of a cat byte. Six had an erythrocyte sedimentation rate over 40. Lymph node ultrasound examination was a useful diagnostic tool. Two patients had splenic granulomas. Lymph node biopsies were obtained in four cases, showing a suppurative granulomatous lymphadenitis in all and a positive Warthin-Starry stain in two. Serology, done in patients without histological confirmation was positive with titles ranging from 1:64 to 1:8192. All patients had a satisfactory outcome with regression of lymphadenopathy. CONCLUSIONS: Infections by Bartonella hemselae occur in the Chilean population and must be considered in the differential diagnosis of regional lymph node enlargement.     

LDPC-based space-time coded OFDM systems: Turbo-EM receiver design with channel state information guessing algorithms

In this paper we study some turbo receiver architectures employing low-density parity check (Ldpc) codes together with orthogonal frequency division multiplexing (Ofdm) for high data rate wireless transmissions. Different demodulation schemes based on expectation-maximization (Em) algorithm are studied along with the channel impulse response (Em) algorithms. We studied differentCir guessing algorithms including the EM-based algorithms such as a space-alternating generalized expectation-maximization algorithm (Sage). It is shown that the proposed turbo-Em receiver employing a soft maximum a posteriori (Map)Em demodulator and a belief propagationLdpc decoder can perform within 1 dB from the ergodic capacity of the studiedMimo ofdm channels. Besides, we find that a suboptimum structure based on a soft interference cancellationMmse filtering demodulator exhibits negligible loss in non-correlated fadingMimo channels but suffer extra performance loss in highly correlatedMimo channels.     

A new cacospongionolide inhibitor of human secretory phospholipase A2 from the Tyrrhenian sponge Fasciospongia cavernosa and absolute configuration of cacospongionolides

A new inhibitor of human secretory phospholipase A2 (PLA2), cacospongionolide E (4a), has been isolated from the Tyrrhenian sponge Fasciospongia cavernosa. The structure was proposed on the basis of spectroscopic data and by chemical transformations. The absolute configuration of cacospongionolides 2a-4a was established using the modified Mosher's method. Cacospongionolide E was the most potent inhibitor toward human synovial PLA2, showing higher potency than the reference compound manoalide and exerting no signs of toxicity on human neutrophils. It showed high activity in the Artemia salina bioassay and moderate toxicity in the fish (Gambusia affinis) lethality assay.