Background: Poor management of postoperative pain results in physiological and psychological side effects with higher morbidity. Erector spinae plane block (ESPB) has shown efficacy in controlling pain in many surgeries. Dexmedetomidine has improved the quality of analgesia in many regional techniques. This study aimed to assess the analgesic outcome of adding dexmedetomidine to bupivacaine in ultrasound (US) guided ESPB for perioperative analgesia for thoracic cancer surgeries. Patients and Methods: In this randomized controlled, double-blind study, 42 patients aged 18-65 years, ASA (American Society of Anesthesiologists) physical status II, scheduled for thoracotomy for cancer surgeries under general anesthesia were included. Patients were allocated into two equal groups: group 1 (ESPB by 28 ml bupivacaine 0.25% + 2 mL saline) and group 2 (ESPB 28 ml bupivacaine 0.25% + 2 mL dexmedetomidine 0.5 µg/kg). Blocks were performed before anesthesia induction. Results: Group 2 consumed lower intraoperative fentanyl and postoperative morphine and had a lower pain score at rest and cough compared to group 1. Group 2 had prolonged time to first request of rescue analgesia compared to group 1. Postoperative nausea and vomiting, and sedation were comparable between both groups. No block-related complications were observed. Conclusions: Adding dexmedetomidine to bupivacaine in US-guided ESPB provided more effective and safe analgesia in thoracotomy.

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One of the recent methods to improve the performance of horizontal axis wind turbine is to attach a winglet at the tip of the blade of these turbines. Winglets reduce the effect of vortex flow at the blade tip and thus improve the performance of the blade. This article presents a parametric study using the computational fluid dynamics (CFD) modeling to investigate the capability of a winglet to increase the turbine power of swept blades as well as straight blades of a horizontal axis wind turbine. The effects of winglet direction, cant angle, and twist angle are studied for two winglet orientations: upstream and downstream directions. The numerical simulation was performed using ANSYS Fluent computational fluid dynamics code. A three-dimensional computational domain, cylindrical rotationally periodic, was used in the computations. The k-ω shear-stress transport turbulence model was adopted to demonstrate turbulence in the flow. Results show that horizontal axis wind turbine with winglet and sweep could enhance more power compared to their equivalent straight or swept blade. The best improvement in the coefficient of power is 4.39% at design tip speed ratio. This is achieved for downstream swept blades with winglets pointing in the upstream direction and having cant and twist angles of 40° and 10°, respectively.

Due to the renewed interest in the effect of misalignment on the dynamic characteristics of journal bearings, this paper presents a study of the effect of misalignment on the dynamic characteristics of journal bearings. A 2D finite difference program is developed and used for this study. The results show that there are a total of 16 stiffness and 16 damping coefficients considering horizontal and vertical displacements and rotations. The variation of these coefficients with journal tilting (i.e., angular misalignment) is illustrated. It is shown that misalignment can have a significant effect on the bearings’ dynamic characteristics.

This work is concerned with the study of the slip phenomenon in centrifugal pumps and the evaluation of its dependence on the flow rate for a four-bladed pump. The finite volume method is used, and the impeller domain is represented by a structured grid topology. The calculations assume a rotationally periodic boundary condition, while the frozen rotor technique is used to model the interaction between the pump impeller and its surrounding volute casing. The simulation uses an implicit time integration of the dynamic equations and is carried out using the commercial ANSYS CFX-solver. Results from the simulation are found in reasonable agreement with the pump performance curve with a maximum relative error of 4% in the range of flow coefficient from 0.8 to 1.2. The calculated values of the slip factor, as a function of the flow rate, show good agreement with the Qiu’s mathematical model while retaining the default value of the defined shape factor F = 0.52. In this particular study, the results show that although the slip factor improves with the increase of either the number of blades or splitter length, the corresponding predicted hydraulic efficiency decreases due to the increasing friction loss.