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Background:. Emerging as an adjunct to breast-conserving surgery, oncoplastic breast surgery seeks to improve the cosmetic and functional outcomes for breast cancer surgery. The objective was to assess the potential advantages of using the latissimus dorsi (LD) flap, in comparison with local tissue rearrangement, in terms of aesthetic results and postoperative problems. Methods:. This study compared the outcomes of patients with a malignant tumor removed from the upper outer quadrant of the breast using a comparative nonrandomized control approach. Participants were split into two groups: reconstruction using local tissue rearrangement was performed on 20 patients (group A), and a pedicled LD flap was used to treat the same number of patients (group B). All patients were examined in the clinics’ outpatient setting. Every 3 months, the medical oncology team would do a thorough clinical assessment. Results:. Better aesthetic outcomes were significantly higher among patients with an LD flap. The LD flap was able to maintain breast shape in 90%, breast volume in 85%, and the nipple-areola complex direction in 90% of patients. Surgeons’ evaluation of both techniques reported significantly higher satisfaction for LD flap than local tissue replacement. Patient satisfaction was significantly higher among patients with an LD flap. With regard to the postoperative complications, there were no significant differences between either group. Conclusions:. Oncoplastic breast surgery with reconstruction using the pedicled LD flap provides maintenance of the shape of female breasts with better aesthetic outcomes and patient and surgeon satisfaction than reconstruction using local tissue rearrangement, with a comparable complication rate.

Paschen curves were studied using different cathode materials such as magnesium, zinc, and carbon graphite by discharge in argon gas of a pressure range between 0.08 and 3 Torr using a parallel plates configuration. The first and second Townsend coefficients ([alpha] and [gamma], respectively) and the ionization efficiency ([eta]) of different cathode materials were deduced from Paschen curves as a function of the reduced field (E/P). The minimum breakdown voltage was found to be about 242 V for Mg material, which has the lowest work function, while carbon graphite has a higher breakdown voltage of 283 V due to its higher work function. The second coefficient [gamma] was increased as a function of E/P and has higher values for materials of lower work functions, and a similar trend of [gamma] is obtained as a function of the ion mean energy. On the other hand, the first coefficient [alpha] has a reverse behavior with both E/P and the work function of the cathode materials compared with the second coefficient. The ionization efficiency of the three cathode materials is identical, as [eta] depends only on the gas properties and not the cathode material. [eta] has a maximum value of about 0.025 [V.sup.-1] for an E/P of about 185 V[cm.sup.-1][Torr.sup.-1], corresponding to the maximum ionizing ability of electrons. The validation of the breakdown results has been confirmed by conferring with other published experimental measurements. Key words: gas breakdown, Paschen curves, cathode work function, first Townsend coefficient, second Townsend coefficient, ionization efficiency. Nous etudions les courbes de Paschen en utilisant des cathodes faites de differents materiaux, a savoir le magnesium, le zinc et le graphite. Les decharge dans un gaz d'argon a une pression allant de 0.08 a 3 Torr, sont faites en utilisant la configuration des plaques paralleles. Nous deduisons les premier et deuxieme coefficients de Townsend ([alpha] et [gamma] respectivement) et l'efficacite d'ionisation ([eta]) des differentes cathodes, a partir des courbes de Paschen en tant que fonctions du champ reduit (E/P). Nous trouvons que la tension de claquage minimale, a 242 V, appartient au Mg qui a le plus bas travail de sortie, alors que pour le graphite, le claquage est a 283 V, a cause de sa plus haute valeur de travail de sortie. Le second coefficient [gamma] est une fonction croissante de E/P et a ses plus hautes valeurs pour les materiaux de plus faible energie de sortie et [gamma] a une tendance similaire en fonction de l'energie moyenne de l'ion. D'un autre cote, le premier coefficient [alpha] a un comportement inverse de [gamma] vis-a-vis de E/P et du travail de sortie de la cathode. L'efficacite d'ionisation des trois types de cathode est identique, parce que [eta] ne depend que des proprietes du gaz, et non du materiau de la cathode. y a une valeur maximale d'environ 0.025 [V.sup.-1] pour E/P d'environ 185 V[cm.sup.-1][Torr.sup.-1], correspondant a la valeur maximale de la facilite d'ionisation des electrons. La validation de ces resultats de claquage a ete confirmee par comparaison avec d'autres mesures experimentales deja publiees. [Traduit par la Redaction] Mots-cles : claquage dans un gaz, courbes de Paschen, travail de sortie de la cathode, premier coefficient de Townsend, second coefficient de Townsend, efficacite d'ionisation., Introduction Electric breakdown of gases is a process in which neutral gas is transformed into a conducting state [1]. The breakdown voltage [V.sub.b] is a function, mainly, of the gas [...]

Starting of three-phase wound rotor induction motors by stepped resistances added in the rotor circuit suffers from several problems. This paper suggestes a novel method of starting by inserting a parallel combination of resistance, inductance and capacitance in the rotor circuit. The proposed method guarantees a smooth and high starting torque over most of the starting period besides a controlled starting current. A mathematical model is developed based on a frequency domain quasi-steady state equivalent circuit. An optimization technique is, then, applied to determine the values of the rotor added elements such that minimum starting time is achieved subject to current and torque constraints. Experimental verification has been carried out, and the computed results are in good agreement with the measured values. Keywords: Induction motors, Methods of starting, Rotor impedance.

This paper presents a nonconventional method for fast starting of three phase wound rotor induction motors. This is achieved through shunting the stator and rotor windings across the supply for a predetermined short period. By this connection, the motor produces an extremely high starting torque. The feasibility of this basic idea has been confirmed through investigating the starting transients corresponding to this mode of operation. For this purpose, a rigorous state space mathematical model has been developed and simulated. The validity of the proposed method and the findings from the mathematical model have been confirmed experimentally. Keywords: Induction motors, Transient analysis, Methods of starting.

A scheme for fast starting of three phase induction motors is proposed. This scheme is based on starting the motor from a single phase supply with the help of a phase balancer properly selected for achieving maximum starting torque. As the speed reaches a predetermined value, a simple centrifugal switch is used to reconnect the motor to the three phase supply. The feasibility of the proposed scheme is proven through the development of a rigorous state space mathematical model and its associated digital simulation, followed by experimental verification. Keywords: Phase balancer, Induction motors, Transient analysis, Methods of starting.

The paper presents an accurate evaluation to the damping and synchronizing torques of a saturated salient pole generator. This objective is achieved by improving the accuracy of saturation representation end the method of computing damping and synchronizing torques. The alternator is represented by using a detailed circuit model which incorporates, properly, the saturation effects under steady-state and dynamic conditions. Based on this detailed model, the damping and synchronizing torque coefficients have been calculated by a least square algorithm which is unrestricted to the degree of complexity of the system. To generalize the conclusion, the damping and synchronizing torque coefficients have been calculated over a wide range of operating conditions. Furthermore, the effect of saturation on the operating boundaries is also exhibited. KEYWORD: Damping and synchronizing torques, saturation, salient-pole generators

This paper presents a comparative study on the starting performance of three phase wound-rotor induction motors under different methods of starting. These methods are on line direct starting, variable rotor resistance starting and double feed starting. In the double feed starting, the rotor winding is connected in parallel with the stator winding across the supply for a predetermined short period. By this connection, the motor produces an extremely high starting torque. For carrying out the investigations sought, a rigorous state space mathematical model has been developed and simulated. The effect of torsional dynamics has been taken into considerations. Keywords: Induction motors, Transient analysis. Starting methods