Residual stress measurements in bevel gear after different production phases

This article discusses residual stress measurements by means of electrochemical removal of material layers with residual stresses and simultaneous measurement of strain on the opposite specimen side with strain gages. Exact measurements are impossible particularly because of the small bevel gear module. With the method presented, the average residual stresses in the tooth root plane and underlying layers are measured. Residual stress distribution after each consecutive production phase is plotted and analyzed. Residual stress measurements enable the engineer to adequately assess each individual production phase and by that improve the quality of the complete production process.     

Application of fuzzy logic and regression analysis for modeling surface roughness in face milliing

The objective of this study is to examine the influence of machining parameters on surface finish in face milling. A new approach in modeling surface roughness which uses artificial intelligence tools is described in this paper. This paper focuses on developing empirical models using fuzzy logic and regression analysis. The values of surface roughness predicted by these models are then compared. The results showed that the proposed system can significantly increase the accuracy of the product profile when compared to the conventional approaches, like regression analysis. The results indicate that the fuzzy logic modeling technique can be effectively used for the prediction of surface roughness in dry machining.     

A study of the mechanisms of corrosion inhibition of AA2024-T3 by vanadates using the split cell technique

The mechanisms of corrosion inhibition of AA2024-T3 by vanadates were studied in this work using the split cell technique and polarization curves. The electrochemical behavior of clear solutions containing metavanadates and orange solutions containing decavanadates was clearly distinctive. Injection of metavanadates to the cathode side of the different split cell setups greatly reduced the galvanic current, indicating a potent inhibition of the oxygen reduction kinetics. The galvanic current never exhibited a transient current peak, suggesting that metavanadates inhibit AA2024-T3 corrosion by a mechanism that does not involve electrochemical reduction. Injection of metavanadate to the anode side of the different split cells had no effect on the galvanic current. Injection of orange decavanadate to the cathode side of the AA2024-T3 split cell resulted in a large current peak, associated with the electrochemical reduction of decavanadate. However, decavanadates did not impart significant corrosion protection.     

Effects of cathodic electrodeposition parameters of cerium oxide film on the corrosion resistance of the 2024 Al alloy

Cerium oxide thin films obtained by cathodic electrodeposition on 2024 aluminium alloy have been studied. The coatings, obtained with electrochemical deposition, offer an effective corrosion protection and require a lower deposition time when compared to chemical conversion coatings. The coatings were obtained at room temperature by deposition from CeCl₃/H₂O₂ aqueous solutions and the influence of several parameters (CeCl₃ concentration, H₂O₂ concentration, deposition time, current intensity) on the corrosion resistance was studied. The composition, morphology and microstructure of the films have been characterized by SEM, XPS and AFM. The corrosion resistance was investigated through potentiodynamic tests in 3% NaCl solution.     

Controlling the hemodynamic response to laryngoscopy and endotracheal intubation

The hemodynamic response to the stress of laryngoscopy and endotracheal intubation does not present a problem for most patients. However, patients with cardiovascular or cerebral disease may be at increased risk of morbidity and mortality from the tachycardia and hypertension resulting from this stress. These hemodynamic effects gained notice after the introduction and use of muscle relaxants, such as curare and succinylcholine, for endotracheal intubation at the time of anesthesia induction. A variety of anesthetic techniques and drugs are available to control the hemodynamic response to laryngoscopy and intubation. The method or drug of choice depends on many factors, including the urgency and length of surgery, choice of anesthetic technique, route of administration, medical condition of the patient, and individual preference. The possible solutions number as many as the medications and techniques available and depend on the individual patient and anesthesia care provider. This paper reviews these medications and techniques to guide the clinician in choosing the best methods.     

Nondestructive study of liquids in single fir seeds using nuclear magnetic resonance and magic angle sample spinning

Magic angle sample spinning reduces line broadening which arises from differences in magnetic susceptibility. NMR spectra of liquid-like components in single fir seeds are recorded with superior resolution and sensitivity, thus facilitating nondestructive determination of oil composition. The results also show thatcis-5,cis-9-octadecadienoic, andcis-5,cis-9,cis-12-octadecatrienoic fatty acids are selectively esterified to the CH```2``-O- group of the glycerol backbone.     

Magnetic orientation studies of synthetic mesophase pitches

Previous studies have shown that mesophase spheres with Brooks-and-Taylor structure are nematic liquid crystals which oriënt with their molecular c-axes perpendicular to a magnetic field. Mesophase spheres in synthetic pitches made from anthracene and naphthalene with AlCl₃ show similar magnetic orientation behavior; however, they have a novel structure, which was elucidated with the use of sensitive tint microscopy and magnetic orientation experiments. In the proposed structure, the aromatic molecules within the bulk of the sphere, are stacked in parallel layers, similar to those in the Brooks-and-Taylor spheres. However, at the interface of the sphere with surrounding isotropic phase, the molecular planes are oriented parallel to the surface, unlike those observed in the Brooks-and-Taylor spheres.