Search

Abstract This paper presents the solutions to the spacecraft relative trajectory reconfiguration problem when a continuous thrust profile is used, and the reference orbit is circular. Given a piecewise continuous thrust profile, the proposed approach enables the computation of the control solution by inverting the linearized equations of relative motion parameterized using the mean relative orbit elements. The use of mean relative orbit elements facilitates the inclusion of the Earth's oblateness effects and offers an immediate insight into the relative motion geometry. Several reconfiguration maneuvers are presented to show the effectiveness of the obtained control scheme. Highlights • Novel linearized relative dynamics model accounting for the J2 perturbation and control. • Novel analytical continuous control solutions for spacecraft formation reconfiguration. • Demonstrated accuracy improvement of continuous strategy as compared with impulsive one. [ABSTRACT FROM AUTHOR]

Background: The commonest surgical procedure for management of morbid obesity in Europe is laparoscopic adjustable gastric banding (LAGB), even though laparoscopic vertical banded gastroplasty (LVBG) is still considered to be a gold standard restrictive option in bariatric surgery. A multicenter prospective study was designed to to assess the efficacy of LVBG in terms of weight loss and complication rates for obese patients who have indications for a restrictive procedure.Patients and Methods: Two-hundred morbidly obese patients (84.5% female) with a mean age of 41 years and mean body mass index (BMI) of 43.2 kg/m(2) underwent LVBG as described by MacLean. Five trocars were placed in standard positions as per laparoscopic upper gastrointestinal surgery. A vertical gastric pouch (30 ml) was created with circular (21 or 25mm) and endolinear stapling techniques, enabling definitive separation of the two parts of the stomach. The gastric outlet was calibrated with either a polypropylene mesh (5.5 cm in length and 1cm in width) or a nonadjustable silicone band. The median follow-up period was 30 months (range, 1-72 months).Results: One case had to be converted to open surgery (gastric perforation) and there was one death secondary to peritonitis of unknown etiology. The morbidity rate was 24%, comprising the following complications: gastric outlet stenosis (8%); staple line leak (2.5%); food trapping (1.5%); peritonitis (1%); thrombophlebitis (1.5%); pulmonary embolism (0.5%); and gastroesophageal reflux (9%). The excess weight loss achieved was 56.7% (1 year), 68.3% (2 years), and 65.1% (3 years).Conclusions: Laparoscopic vertical banded gastroplasty is an effective procedure for the surgical management of morbid obesity, especially for patients who present hyperphagia but are unable to manage the constraints of adjustable gastric banding. Laparoscopic vertical banded gastroplasty is safe, as demonstrated by an acceptable complication rate, of which gastric outlet stenosis, staple line leakage, and gastroesophageal reflux predominate. [ABSTRACT FROM AUTHOR]