Performance analysis of flexible aircraft with active control

Small perturbation equations of motion of a flexible aircraft with an active control technology (ACT) system were developed to evaluate the stability and performance of the controlled aircraft. The total aircraft system was formulated in state vector format and the system of equations was completed with fully unsteady and low frequency aerodynamics for arbitrary, complex configurations based on a potential aerodynamic method. The ACT system equations were incorporated in the digital computer program FCAP (Flight Control Analysis Program) which can be used for the analysis of complete aircraft configurations, including control system, with either low frequency or fully unsteady aerodynamics. The application of classical performance analyses including frequency response, poles and zeros, mean square response, and time response in FCAP in state vector format was discussed

Aerodynamic interference effects on tilting proprotor aircraft

The Green's function method was used to study tilting proprotor aircraft aerodynamics with particular application to the problem of the mutual interference of the wing-fuselage-tail-rotor wake configuration. While the formulation is valid for fully unsteady rotor aerodynamics, attention was directed to steady state aerodynamics, which was achieved by replacing the rotor with the actuator disk approximation. The use of an actuator disk analysis introduced a mathematical singularity into the formulation; this problem was studied and resolved. The pressure distribution, lift, and pitching moment were obtained for an XV-15 wing-fuselage-tail rotor configuration at various flight conditions. For the flight configurations explored, the effects of the rotor wake interference on the XV-15 tilt rotor aircraft yielded a reduction in the total lift and an increase in the nose-down pitching moment. This method provides an analytical capability that is simple to apply and can be used to investigate fuselage-tail rotor wake interference as well as to explore other rotor design problem areas

Steady, oscillatory, and unsteady subsonic Aerodynamics, production version 1.1 (SOUSSA-P1.1). Volume 2: User/programmer manual

A user/programmer manual for the computer program SOUSSA P 1.1 is presented. The program was designed to provide accurate and efficient evaluation of steady and unsteady loads on aircraft having arbitrary shapes and motions, including structural deformations. These design goals were in part achieved through the incorporation of the data handling capabilities of the SPAR finite element Structural Analysis computer program. As a further result, SOUSSA P possesses an extensive checkpoint/ restart facility. The programmer's portion of this manual includes overlay/subroutine hierarchy, logical flow of control, definition of SOUSSA P 1.1 FORTRAN variables, and definition of SOUSSA P 1.1 subroutines. Purpose of the SOUSSA P 1.1 modules, input data to the program, output of the program, hardware/software requirements, error detection and reporting capabilities, job control statements, a summary of the procedure for running the program and two test cases including input and output and listings are described in the user oriented portion of the manual

Laparoscopy for extraperitoneal rectal cancer reduces short-term morbidity: Results of a systematic review and meta-analysis

BACKGROUND: The role of laparoscopy in the treatment of extraperitoneal rectal cancer is still controversial. The aim of the study was to evaluate differences in safety of laparoscopic rectal resection for extraperitoneal cancer, compared with open surgery. MATERIALS AND METHODS: A systematic review from 2000 to July 2012 was performed searching the MEDLINE and EMBASE databases (PROSPERO registration number CRD42012002406). We included randomized and prospective controlled clinical studies comparing laparoscopic and open resection for rectal cancer. Primary endpoints were 30-day mortality and morbidity. Then a meta-analysis was conducted by a fixed-effect model, performing a sensitivity analysis by a random-effect model. Relative risk (RR) was used as an indicator of treatment effect. RESULTS: Eleven studies, representing 1684 patients, met the inclusion criteria: four were randomized for a total of 814 patients. Mortality was observed in 1.2% of patients in the laparoscopic group and in 2.3% of patients in the open group, with an RR of 0.56 (95% CI 0.19–1.64, p = 0.287). The overall incidence of short-term complications was lower in the laparoscopic group (31.5%) compared to the open group (38.2%), with an RR of 0.83 (95% CI 0.73–0.94, p = 0.004). Surgical complications, wound complications, blood loss and the need for blood transfusion, time for bowel movement recovery, food intake recovery, and hospital stay were significantly lower or less frequent in the laparoscopic group. The incidence of intra-operative injuries, anastomotic leakages, and surgical re-interventions was similar in the two groups. Only operative time was in favour of the open group. CONCLUSIONS: Based on the evidence of both randomized and prospective controlled series, mortality was lower after laparoscopy although not significantly so, while the short-term morbidity RR, including subgroup analysis, was significantly lower after laparoscopy for extraperitoneal rectal cancer compared to open surgery

Formation and transport of oxidized reactive nitrogen, ozone, and secondary organic aerosol in Tokyo

Measurements of the major reactive nitrogen species (NOy)i (NOx, peroxyacyl nitrates, HNO3, and particulate nitrate (NO3-), total reactive nitrogen (NOy), volatile organic compounds, OH and HO2, and organic aerosol were made near the urban center of Tokyo in different seasons of 2003-2004 to study the processes involving oxidized forms of reactive nitrogen and O3. Generally, NOx constituted the dominant fraction of NOy throughout the seasons. The NOx/NOy and HNO3/NOy ratios were lowest and highest, respectively, in summer, owing to the seasonally high OH concentration. The fraction of NOy that remained in the atmosphere after emission (RNOy) decreased with the decrease in the NOx/NOy ratio in summer and fall. It is likely that the median seasonal-diurnal variations Of Ox = O3 + NO2 were controlled by those of the background O3 levels, photochemical O3 formation, and vertical transport. Ox showed large increases during midday under stagnant conditions in mid-August 2004. Their in situ production rates calculated by a box model were too slow to explain the observed increases. The high Ox was likely due to the accumulation of Ox from previous days in the upper part of the boundary layer (BL) followed by transport down to near the surface by mixing after sunrise. Considering the tight correlation between Ox and secondary organic aerosol (SOA), it is likely that SOA also accumulated during the course of sea-land breeze circulation in the BL. Copyright 2008 by the American Geophysical Union

Treatment of Lower-GI Post-Surgical Fistulas With the Over-the-Scope Clip

AbstractPost-surgical colorectal leaks and fistulas are severe complications that dramatically increase morbidity and mortality. Over-the-scope clip (OTSC) application, introduced in clinical practice in 2007, represents an innovative technique to seal the visceral wall for acute and chronic colorectal post-surgical leaks and fistula management. Endoscopic closure of colorectal post-surgical leaks and fistulas with OTSC is a safe technique that accomplishes a high success rate in both acute and chronic cases, including rectovaginal, rectovesical, and colocutaneous fistulas. Overall success rate is higher than 80%, as reported in the literature, in both acute and chronic situations. No OTSC-related complications have been described in the lower gastrointestinal tract so far. This article is part of an expert video encyclopedia

Crystallographic disorder and electron scattering on structural two-level systems in ZrAs1.4Se0.5

Single crystals of ZrAs1.4Se0.5 (PbFCl type structure) were grown by chemical vapour transport. While their thermodynamic and transport properties are typical for ordinary metals, the electrical resistivity exhibits a shallow minimum at low temperatures. Application of strong magnetic fields does not influence this anomaly. The minimum of the resistivity in ZrAs1.4Se0.5 apparently originates from interaction between the conduction electrons and structural two-level systems. Significant disorder in the As-Se substructure is inferred from X-ray diffraction and electron microprobe studies