Abstract: In practical engineering systems, unknown actuator, sensor or system component faults frequently occur, which results from component and interconnection failures, degrade control performance, system stability, and profitability, and even arise hazardous situation. To avoid abnormal activity like faults and maintain system control performance subject to faults occurring into the system, the Fault-tolerant Control (FTC) is a realistic approach to address the unwanted situation. The two-tank conical system is widely used in chemical and food process industries because of its greater advantages. The non-interacting configuration of the two-tank conical system is highly nonlinear due to its shape and varying area of the tank thought the height of the tank, as a consequence level control of this system is extremely difficult. The paper attributes to design a Passive Fault-tolerant Control Strategy (PFTCS) for a Two-tank conical Non Interacting Level Control System (TTCNILCS) subject to the major system (leak), sensor, and actuator faults with external process disturbances. PFTC will increase system control performance and system stability acceptable level in the presence of sensor, system, and actuator faults. The simulation results demonstrate the proposed PFTC strategy has definite fault tolerant ability against the system and actuator faults also it has good disturbance rejection capability. To verify the efficacy of the proposed PFTC strategy Mean Square Error (MSE) and Root Mean Square Error (RMSE) Integral Absolute Error (IAE) indices are used.

Resumen: En los sistemas de ingeniería práctica, con frecuencia ocurren fallas desconocidas en el actuador, sensor o componente del sistema, que resultan de fallas de componentes e interconexión, degradan el rendimiento del control, la estabilidad del sistema y la rentabilidad, e incluso surgen situaciones peligrosas. Para evitar actividades anormales como fallas y mantener el rendimiento del control del sistema sujeto a fallas que ocurren en el sistema, el Control tolerante a fallas (FTC) es un enfoque realista para abordar la situación no deseada. El sistema de dos tanques cónicos se usa ampliamente en las industrias químicas y de procesos alimentarios debido a sus mayores ventajas. La configuración no interactiva del sistema de dos tanques cónicos es altamente no lineal debido a su forma y al área variable del tanque a través de la altura del tanque, por lo que el control de nivel de este sistema es extremadamente difícil. Este trabajo se lo realiza para diseñar una estrategia de control tolerante a fallas pasivas (PFTCS) para un sistema de control de nivel sin interacción de dos tanques cónicos (TTCNILCS) sujeto al sistema principal (fugas), fallas del actuador con perturbaciones externas del proceso. PFTC aumentará el rendimiento del control del sistema y la estabilidad del sistema en un nivel aceptable en presencia de fallas del sistema y del actuador. Los resultados de la simulación demuestran que la estrategia PFTC propuesta tiene una capacidad de tolerancia a fallas definida contra las fallas del sistema y del actuador, y también tiene una buena capacidad de rechazo de perturbaciones. Para verificar la eficacia de la estrategia de PFTC propuesta, se utilizan los índices de Error absoluto cuadrático medio (MSE) y Error cuadrático medio (RMSE).

PURPOSE: Nerve sparing radical prostatectomy is the gold standard for the treatment of prostate cancer. Over the past decade, more and more surgeons and patients are opting for a robot-assisted procedure. The purpose of this paper is to briefly review different techniques and outcomes of nerve sparing robot assisted laparoscopic prostatectomy (RALP). MATERIALS AND METHODS: We performed a MEDLINE search from 2001 to 2009 using the keywords “robotic prostatectomy”, “cavernosal nerve”, “pelvic neuroanatomy”, “potency”, “outcomes” and “comparison”. Extended search was also performed using the references from these articles. RESULTS: Several techniques of nerve sparing are available in literature for RALP, which have been described in this manuscript. These include, “the veil of Aphrodite”, “athermal retrograde neurovascular release”, “clipless antegrade nerve sparing” and “clipless cautery free technique”. The comparative and the non comparative series showing outcomes of RALP have been described in the manuscript. CONCLUSIONS: The basic principles for nerve sparing revolve around minimal traction, athermal dissection, and approaching the correct planes. It has not been documented if any one technique is better than the other. Regardless of technique, patient selection, wise clinical judgment and a careful dissection are the keys to achieve optimal oncological outcomes following RALP.

OBJECTIVE: Optical coherence tomography (OCT) is a unique technology, developed to provide high resolution, cross sectional images of human tissue. The objective of this study was to explore the feasibility of OCT for the evaluation of positive surgical margins and extra capsular extension in robotic prostatectomy specimens and compare it to histopathology. MATERIAL AND METHODS: Radical prostatectomy was performed in 100 patients. Twenty OCT images of each specimen were taken from the base of the seminal vesicles (SV), apical and vesicle margins, peripheral and posterolateral area and any palpable nodule. Predictions were made regarding positive surgical margin, SV involvement, capsular invasion and compared with the final histopathology. RESULTS: A total of 2000 OCT images were taken and analyzed. Out of 100 specimens, 85 had T2 disease, 15 had T3 disease with a median Gleason's score of 7 (range 6 to 9) and 10 had positive surgical margins. We predicted 21 specimens to have positive margins based on OCT images out of which 7 were truly positive and 14 were falsely positive. Based on OCT images, 79 specimens were predicted to have negative margins out of which 76 were truly negative and 3 were falsely negative. We found the sensitivity, specificity, positive predictive value and negative predictive value to be 70%, 84%, 33% and 96% respectively. CONCLUSION: Our initial feasibility study established the template for the visual OCT characteristics of the prostate, SV and cancerous tissue. The negative predictive value of evaluating surgical margins was high.

Objectives: To present a contemporary review of the functional outcomes following robotic-assisted radical prostatectomy based on published postoperative erectile function and urinary continence data. Methods: A review of the available literature on Medline and PubMed databases was performed. Results: Factors affecting erectile function include age, preoperative SHIM scores, co-morbidities and nerve sparing techniques. Large robotic-assisted laparoscopic radical prostatectomy (RALP) series like the Vattikuti Institute’s and Ohio State University’s demonstrate early potency outcomes: 70% and 80% of patients, respectively, who underwent bilateral nerve sparing and had a pre-operative SHIM score 17, regained potency after a follow-up of 12 months. This has also been reproduced by smaller series, where 43% of patients achieved potency within 3 months postop and 68%, 79% of patients who underwent unilateral or bilateral nerve sparing, respectively, were able to have intercourse with or without PDE5 inhibitors after 12 months follow-up. Postoperative continence rates after RALP for larger series are 76%-92% and 95.2%-98% while that for smaller series range from 76% and 89% at 3 and 12 months, respectively. Conclusions: RALP is a safe, minimally invasive procedure that produces functional outcomes comparable to contemporary results of both open and laparoscopic prostatectomy.

Objetivos: Presentar una revisión actual de los resultados funcionales de la prostatectomía radical asistida por robot, basada en los datos publicados postoperatoriamente, relativos a función eréctil y continencia urinaria. Métodos: Se realizó una revisión de la literatura disponible en las bases de datos de Medline y PubMed. Resultados: Los factores que afectan la función eréctil incluyen la edad, la puntuación preoperatoria en el SHIM (Sexual Health Inventory for Men), co-morbilidad y técnicas de preservación nerviosa. Las grandes series de prostatectomía radical laparoscópica asistida por robot (PRLAR), como las del Instituto Vattikuti y la Ohio State University, comunican sus resultados iniciales de potencia sexual: 70% y 80% de los pacientes, respectivamente, que se sometieron a prostatectomía con preservación neurovascular bilateral y tenían un SHIM preoperatorio 17, recuperaron la potencia después de un seguimiento de 12 meses. Esto se ha producido también en otras series más pequeñas, donde el 43% de los pacientes recuperaron la potencia en los tres primeros meses postoperatorios y un 68%, 79% respectivamente de los pacientes que se sometieron a preservación neurovascular unilateral o bilateral, fueron capaces de mantener relaciones sexuales con o sin IPDE5 tras 12 meses de seguimiento. Los índices postoperatorios de continencia después de la PRLAR en las series más grandes son del 76%-92% y del 95.2%-98%, mientras que en las más pequeñas varían desde el 76% y el 89% a 3 y12 meses, respectivamente. Conclusiones: La PRLAR es un procedimiento mínimamente invasivo que presenta resultados funcionales comparables a los publicados en la actualidad de prostatectomía abierta o laparoscópica.