Performance analysis of ladder-secondary-linear induction motor with two different secondary types using Magnetic Equivalent Circuit.

This paper proposes a Magnetic Equivalent Circuit (MEC) method to model the Ladder-Secondary-Linear Induction Machines (LS-LIMs), where the model accuracy can be determined as desired. This method makes it much easier to change parameters of motor include poles and slots number as well as its dimension than the Finite Element Method (FEM). The end-effect phenomenon is considered in the model by two virtual zones with arbitrary length at the both exit and entrance ends of the primary for saturable LS-LIMs. The proposed MEC method also makes it possible to investigate the motor performance under different secondary structures (two types), bars material and their width. Finally, FEM and experimental results are given to evaluate the accuracy of the proposed method, and simulation time is compared with 2D-FEM. In a general overview, modeling the end-effect and saturation phenomena, analyzing the impacts of different secondary structures and bars width on the performance of motor are studied by the suggested MEC method in the present work.

Efficient removal of crystal violet from aqueous solutions with Centaurea stem as a novel biodegradable bioadsorbent using response surface methodology and simulated annealing: Kinetic, isotherm and thermodynamic studies.

The novel green bioadsorbent, Centaurea stem, was utilized for crystal violet removal from aqueous solutions. SEM and FT-IR were used for characterization of Centaurea stem. The effects of the pH, time, temperature, bioadsorbent amount, and initial dye concentration were investigated. Response surface methodology was used to depict the experimental design and the optimized data of pH 12.57, time 19.661, temperature 38.94 °C, amount of bioadsorbent 12.218 mg, and initial dye concentration 36.62 mg L-1 were achieved. Moreover, artificial neural network (ANN) and simulated annealing (SA) were applied for prediction and optimization of the process respectively. The SA acquired optimum conditions of 10.114, 7.892 min, 25.127 °C, 64.405 mg L-1, 14.54 mg for pH, time, temperature, initial dye concentration, and bioadsorbent amount, respectively which were more close to the experimental results and indicated higher ability of SA-ANN in prediction and optimization of the process. The adsorption isotherms confirm the experimental data were appropriately fitted to the Langmuir model with high adsorption capacity of 476.190 mg g-1. The thermodynamic parameters were evaluated. The positive ΔH° and ΔS° values described endothermic nature of adsorption. The adsorption of crystal violet followed the pseudo-second order kinetic model.

Meropenem Utilization Evaluation in a Referral Teaching Hospital in Iran.

OBJECTIVE: Inappropriate use of antibiotics is associated with detrimental effects including emergence of antibiotic resistance. This study aimed to evaluate the use of meropenem, an extended-spectrum antibiotic, in a referral teaching hospital to detect different types of errors in its prescription. METHODS: In a cross-sectional study performed over a 6-month period (2014-2015), hospitalized adult patients who received meropenem for any indication were randomly selected. The collected data included the indication for prescription and its correctness, the basis of prescription (empirical or culture based), administered dose, duration of treatment, the status of demanding sample culture in the case of empirical prescription, the status of dose adjustment in the case of renal impairment, and the treatment outcome. FINDINGS: Over the study period, 123 patients were evaluated. The most frequent indication for prescription of meropenem was pneumonia (31.7%) and soft-tissue infections (18.7%). Out of these prescriptions, 62.6% (77 prescriptions) were incorrect. All meropenem prescriptions were initially empirical. Furthermore, sample culture and antibiotic susceptibility test were requested for only 52% of patients (n = 66). Treatment duration was correct for 53.7% of patients. Seventeen patients (13.8%) received an inappropriate dose of the antibiotic. Furthermore, of 51 patients who needed meropenem dose adjustment because of renal impairment, 17 patients (33.33%) received unadjusted dose. CONCLUSION: High rate of errors exists in the utilization of meropenem in our hospital, especially in the rank order of selection for treatment (indication), dose adjustment, and treatment duration. Therefore, modification strategies are necessary to promote the rational use of meropenem in this center.

Cage-rotor induction motor inter-turn short circuit fault detection with and without saturation effect by MEC model.

The inter-turn short fault for the Cage-Rotor-Induction-Machine (CRIM) is studied in this paper and its local saturation is taken into account. However, in order to observe the exact behavior of machine, the Magnetic-Equivalent-Circuit (MEC) and nonlinear B-H curve are proposed to provide an insight into the machine model and saturation effect respectively. The electrical machines are generally operated near to their saturation zone due to some design necessities. Hence, when the machine is exposed to a fault such as short circuit or eccentricities, it is operated within its saturation zone and thus, time and space harmonics are integrated and as a result, current and torque harmonics are generated which the phenomenon cannot be explored when saturation is dismissed. Nonetheless, inter-turn short circuit may lead to local saturation and this occurrence is studied in this paper using MEC model. In order to achieve the mentioned objectives, two and also four-pole machines are modeled as two samples and the machines performances are analyzed in healthy and faulty cases with and without saturation effect. A novel strategy is proposed to precisely detect inter-turn short circuit fault according to the stator׳s lines current signatures and the accuracy of the proposed method is verified by experimental results.