Progress in Operational Analysis of Launch Vehicles in Nonstationary Flight

This paper presents recent results in an ongoing effort to understand and develop techniques to process launch vehicle data, which is extremely challenging for modal parameter identification. The primary source of difficulty is due to the nonstationary nature of the situation. The system is changing, the environment is not steady, and there is an active control system operating. Hence, the primary tool for producing clean operational results (significant data lengths and data averaging) is not available to the user. This work reported herein uses a correlation-based two step operational modal analysis approach to process the relevant data sets for understanding and development of processes. A significant drawback for such processing of short time histories is a series of beating phenomena due to the inability to average out random modal excitations. A recursive correlation process coupled to a new convergence metric (designed to mitigate the beating phenomena) is the object of this study. It has been found in limited studies that this process creates clean modal frequency estimates but numerically alters the damping

Characterization of Microgravity Environment on Mir

This paper presents the microgravity analysis results using dynamic response data collected during the first phase of the Mir Structural Dynamics Experiment (MiSDE). Although MiSDE was designed and performed to verify structural dynamic models, it also provided information for determining microgravity characteristics of the structure. This study analyzed ambient responses acquired during orbital day-to-night and night-to-day transitions, crew treadmill and ergometer exercises, and intentional crew activities. Acceleration levels for one-third octave bands were calculated to characterize the microgravity environment of the station. Spectrograms were also used to analyze the time transient nature of the responses. Detailed theoretical background and analysis results will also be included in the final draft

A Coupled Approach for Structural Damage Detection with Incomplete Measurements

This historical work couples model order reduction, damage detection, dynamic residual/mode shape expansion, and damage extent estimation to overcome the incomplete measurements problem by using an appropriate undamaged structural model. A contribution of this work is the development of a process to estimate the full dynamic residuals using the columns of a spring connectivity matrix obtained by disassembling the structural stiffness matrix. Another contribution is the extension of an eigenvector filtering procedure to produce full-order mode shapes that more closely match the measured active partition of the mode shapes using a set of modified Ritz vectors. The full dynamic residuals and full mode shapes are used as inputs to the minimum rank perturbation theory to provide an estimate of damage location and extent. The issues associated with this process are also discussed as drivers of near-term development activities to understand and improve this approach

Transvesical natural orifice transluminal endoscopic surgery (NOTES) nephrectomy with kidney morcellation: a proof of concept study

The authors acknowledge Karl Storz, Richard Wolf and Covidien for their support with equipment.What's known on the subject? and What does the study add? Until now, the transvaginal approach has been the only method of removing larger specimens from the abdominal cavity using natural orifi ce transluminal endoscopic surgery. There has been no means of extracting larger specimens in men and the means are restricted even in women, particularly in young women. The present study shows that the diffi culty of large specimen retrieval can be overcome, irrespective of the diameter of the chosen port, through natural orifi ces using morcellation.OBJECTIVE To show, in a porcine model, the feasibility of a complete transvesical natural orifi ce transluminal endoscopic surgery (NOTES) nephrectomy with kidney extraction after morcellation through the same port. MATERIALS AND METHODS Transvesical nephrectomy and morcellation were performed in six pigs at Minho University, Braga, Portugal after institutional review board approval. The transvesical port and the cystotomy were created under the guidance of a ureteroscope, while the remaining steps were done under the guidance of an operating telescope. Dissection of the renal vessels and kidney was performed using dissection grasping forceps and a vessel sealing system (LigaSure TM ; Covidien, Mansfi eld, MA, USA) and morcellation was done using a Piranha TM morcellator (Richard Wolf, Knittlingen, Germany). RESULTS There were no complications related to the creation of transvesical access. • The image provided by the telescope was superior to that of the ureteroscope, especially underwater. Morcellation was quick and effective, with the support of a fi xing needle through the abdominal wall, designed to fi x the kidney, after laceration of a bowel loop occurred in the first experiment. It was found that technical improvements are needed to ensure safety of NOTES morcellation. CONCLUSIONS Kidney morcellation after nephrectomy, using a natural orifi ce exclusively, is feasible. • Despite technical limitations, this proof of concept study can be regarded as a potential step towards the application of NOTES in urology.This study was supported by the Science & Technology Foundation (FCT), Portugal – PTDC/SAU-OSM/105578/2008

Robotic partial nephrectomy for posterior tumors through a retroperitoneal approach offers decreased length of stay compared with the transperitoneal approach: A propensity-matched analysis

INTRODUCTION: We sought to compare surgical outcomes between transperitoneal and retroperitoneal robotic partial nephrectomy (RPN) for posterior tumors. PATIENTS AND METHODS: Using our multi-institutional RPN database, we reviewed 610 consecutive cases for posterior renal masses treated between 2007 and 2015. Primary outcomes were complications, operative time, length of stay (LOS), surgical margin status, and estimated glomerular filtration rate (eGFR) preservation. Secondary outcomes were estimated blood loss, warm ischemia time (WIT), disease recurrence, and disease-specific mortality. Due to significant differences in treatment year and tumor size between approaches, retroperitoneal cases were matched 1:4 to transperitoneal cases based on propensity scores using the greedy algorithm. Outcomes were compared between approaches using the chi-square and Mann-Whitney U tests. RESULTS: After matching, 296 transperitoneal and 74 retroperitoneal cases were available for analysis, and matched groups were well balanced in terms of treatment year, age, gender, race, American Society of Anesthesiologists physical status classification (ASA) score, body mass index, tumor laterality, tumor size, R.E.N.A.L. (radius, exophytic/endophytic properties, nearness of tumor to the collecting system or sinus, anterior/posterior, location relative to polar lines) score, and hilar location. Compared with transperitoneal, the retroperitoneal approach was associated with significantly shorter mean LOS (2.2 vs 2.6 days, p = 0.01), but longer mean WIT (21 vs 19 minutes, p = 0.01). Intraoperative (p = 0.35) and postoperative complications (p = 0.65), operative time (p = 0.93), positive margins (p = 1.0), and latest eGFR preservation (p = 0.25) were not significantly different between approaches. No differences were detected in the other outcomes. CONCLUSIONS: Among high-volume surgeons, transperitoneal and retroperitoneal RPN achieved similar outcomes for posterior renal masses, although with slight differences in LOS and WIT. Retroperitoneal RPN may be an effective option for the treatment of certain small posterior renal masses

Probabilistic Structural Health Monitoring of the Orbiter Wing Leading Edge

A structural health monitoring (SHM) system can contribute to the risk management of a structure operating under hazardous conditions. An example is the Wing Leading Edge Impact Detection System (WLEIDS) that monitors the debris hazards to the Space Shuttle Orbiter s Reinforced Carbon-Carbon (RCC) panels. Since Return-to-Flight (RTF) after the Columbia accident, WLEIDS was developed and subsequently deployed on board the Orbiter to detect ascent and on-orbit debris impacts, so as to support the assessment of wing leading edge structural integrity prior to Orbiter re-entry. As SHM is inherently an inverse problem, the analyses involved, including those performed for WLEIDS, tend to be associated with significant uncertainty. The use of probabilistic approaches to handle the uncertainty has resulted in the successful implementation of many development and application milestones

Public perception of "scarless" surgery : a critical analysis of the literature

Evidence relating to the perception and view of patients and physicians on natural orifice transluminal endoscopic surgery (NOTES) and laparoendoscopic single-site surgery (LESS) was scrutinized. A comprehensive literature search was performed through PubMed. A total of 18 studies were included in the analysis. Patients demonstrated interest in scarless surgery, with a preference for LESS over NOTES. Safety and efficacy remain the key factors in the decision-making process of patients. With more information about the safety and reproducibility of LESS and NOTES, and with improved educational efforts, patients and physicians alike may feel more comfortable in widespread application of scarless surgery.(undefined

Prospective multi-center study of oncologic outcomes of robot-assisted partial nephrectomy for pT1 renal cell carcinoma

BACKGROUND: Partial nephrectomy has been increasingly recommended over radical nephrectomy for the management of small renal masses based on improved renal functional outcomes without sacrifice of oncologic effectiveness. Robot-assisted partial nephrectomy (RAPN) has been introduced in an effort to offer another minimally invasive option for nephron-sparing surgery. However, reports of RAPN have been limited to short-term perioperative outcomes. The goal of this study is to report and evaluate the initial oncologic outcomes of RAPN. Utilizing prospectively obtained data on RAPN performed by four surgeons at four separate tertiary care centers, we selected patients with unilateral, localized, non-familial, pathologically-confirmed pT1 renal cell carcinoma and a minimum post-operative follow-up of 12 months. METHODS: Utilizing prospectively obtained data on RAPN performed by four surgeons at four separate tertiary care centers, we selected patients with unilateral, localized, non-familial, pathologically-confirmed pT1 renal cell carcinoma and a minimum post-operative follow-up of 12 months. Survival analysis (disease-free, cancer-specific, and overall survival) was performed, and Kaplan-Meier curves were generated. RESULTS: RAPN was performed in 124 patients with a median tumor size of 3.0 cm (IQR 2.2-4.2 cm). Median follow-up was 29 months (range 12-46 months). Positive parenchymal surgical margins occurred in two patients (1.6 %), both of whom were recurrence-free at 30 and 34 months after surgery. The three-year Kaplan-Meier estimated disease-free survival was 94.9 %, cancer-specific survival was 99.1 %, and overall survival was 97.3 %. CONCLUSIONS: In our cohort of patients with small renal carcinomas who were followed for a median of 29 months, recurrence and survival outcomes were similar to those reported for open and laparoscopic partial nephrectomy. Further long-term outcomes will be needed to definitively claim that RAPN is oncologically equivalent to other surgical approaches