Orion Capsule Parachute Assembly System (CPAS) Overload Testing Approach and Results

The qualification of the Orion Capsule Parachute Assembly System (CPAS) system includes exposure to loads and dynamic pressures above the required values as validation of the parachutes' structural integrity. As outlined in the certification plan, each of the four parachutes of the system are to be subjected to 110% of their respective maximum dynamic pressure requirements. The Main and Drogue parachutes have satisfied this overload condition in drop testing and due to cost and schedule constraints, the Forward Bay Cover Parachute (FBCP) and Pilot parachute were subjected to the overload condition in the ground testing described in this document. The test objectives and pass/fail criteria were established and require the parachutes to achieve and maintain a target riser load (associated with a minimum of 110% dynamic pressure overload) for a minimum of three seconds while sustaining no failures of any structural members (vent hoop, radials, suspension line) or any damage which propagates into catastrophic failure of the canopy. Considering the assumptions and limitations associated with the ground testing (primarily non-uniform flow field of the ground test system and variations in parachute manufacturing), a method of establishing the desired overload condition was determined by the technical community and covers the 2-sigma bounds of the drag area distribution derived from drop testing. On June 27, 2017 the testing was executed at the High Velocity Airflow System (HiVAS) facility located at the Weapon Survivability Laboratory (WSL) at the Naval Air Warfare Center, Weapons Division (NAWCWD) China Lake. Engineering Development Unit (EDU) parachutes were used as pathfinders to gain experience with achieving the test conditions. Additional runs were executed to measure the airflow at the same location as the canopy skirt, although this data is not required to satisfy the test objectives and parachute pass/fail criteria. The qualification parachutes were successfully exposed to the target conditions and sustained only minor damage

Cell Mergers and Their Impact on Cloud-to-Ground Lightning Over the Houston Area

A previous hypothesis advanced from observational studies such as METROMEX suggests that the intensity, frequency, and organization of cumulus convection may be impacted by the forcing of enhanced merger activity downstream of urban zones. A resulting corollary is that cities may exert an indirect anthropogenic forcing of parameters related to convection and associated phenomena such as lightning and precipitation. This paper investigates the urban merger hypothesis by examining the role of convective cell mergers on the existence and persistence of the Houston lightning "anomaly", a local maximum in cloud-to-ground (CG) lightning activity documented to exist over and east of Houston. Using eight summer seasons of peak columnar radar reflectivity, CG lightning data and a cell-tracking algorithm, a two-dimensional cell merger climatology is created for portions of eastern Texas and Louisiana. Results from the tracking and analysis of over 3.8 million cells indicate that merger-driven enhancements in convection induce a positive response (O 46%) in ground-flash densities throughout the domain, with areas of enhanced lightning typically being co-located with areas of enhanced merger activity. However, while mergers over the Houston area (relative to elsewhere in the domain) do result in more vigorous convective cells that produce larger CG flash densities, we find that CG lightning contributions due to mergers are distributed similarly throughout the domain. Hence while we demonstrate that cell mergers do greatly impact the production of lightning, the urban cell merger hypothesis does not uniquely explain the presence of a local lightning maximum near and downstream of Houston

NASA CPAS Drogue Textile Riser Feasibility Study

Steel cable was chosen for the lower end of the drogue and main parachute risers on NASA's Orion Multi Purpose Crew Vehicle Parachute Assembly System (CPAS) to protect the risers from extreme temperatures and abrasion should they contact the crew module during deployment, as was done for Apollo. Due to the weight and deployment complexity inherent in steel, there was significant interest in the possibility of substituting textile for steel for the drogue and main parachute risers. However, textile risers could be damaged when subjected to high temperature and abrasion. Investigations were consequently performed by a subset of the authors to determine whether sacrificial, non-load-bearing textile riser covers could be developed to mitigate the thermal and abrasion concerns. Multiple material combinations were tested, resulting in a cover design capable of protecting the riser against severe riser/crew module contact interactions. A feasibility study was then conducted to evaluate the performance of the textile drogue riser cover in relevant abrasive environments. This paper describes the testing performed and documents the results of this feasibility study

Comparison of UVB and UVC irradiation disinfection efficacies on Pseudomonas Aeruginosa biofilm

Disinfection routines are important in all clinical applications. The uprising problem of antibiotic resistance has driven major research efforts towards alternative disinfection approaches, involving light-based solutions. Pseudomonasaeruginosa (P. aeruginosa) is a common bacterium that can cause skin, soft tissue, lungs, kidney and urinary tract infections. Moreover, it can be found on and in medical equipment causing often cross infections in hospitals. The objective of this study was to test the efficiency, of two different light-based disinfection treatments, namely UVB and UVC irradiation, on P. aeruginosa biofilms at different growth stages. In our experiments a new type of UV light emitting diodes (LEDs) were used to deliver UV irradiation on the biofilms, in the UVB (296nm) and UVC (266nm) region. The killing rate was studied as a function of dose for 24h grown biofilms. The dose was ramped from 72J/m2 to 10000J/m2. It was shown that UVB irradiation was more effective than UVC irradiation in inactivating P. aeruginosa biofilms. No colony forming units (CFU) were observed for the UVB treated biofilms when the dose was 10000 J/m2 (CFU in control sample: 7.5 x 104). UVB irradiation at a dose of 20000J/m2 on mature biofilms (72h grown) resulted in a 3.9 log killing efficacy. The fact that the wavelength of 296nm exists in daylight and has such disinfection ability on biofilms gives new perspectives for applications within disinfection at hospitals

Use of Blends in Commercial Refrigeration Systems: Fractionation characteristics and material compatibility of R448A

The development of lower global warming potential (GWP) blends offers an alternative for the widely used high GWP fluids such as R404A. Commercial refrigeration systems for supermarkets are a common example for such systems. These kinds of systems show relatively large refrigerant leakage rates of 15% to 20% per year. The newly developed R404A lower GWP alternatives are zeotropic blends, meaning they show a temperature glide during phase change processes in the evaporator and condenser of the system. Because of the glide, there is a concern within end users that the blend components could separate, or fractionate, during a leak event. Â This paper will describe the results from tests carried out to determine the effect of refrigerant fractionation and its effect on the performance of an actual refrigeration system subject to multiple leak events. The second part of this paper provides characteristics for the solubility and miscibility of R448A with POE oil and results from a material compatibility study of R448A with common materials used in refrigeration equipment

Amphiphilic polyanhydride nanoparticles stabilize bacillus anthracis protective antigen

Advancements toward an improved vaccine against Bacillus anthracis, the causative agent of anthrax, have focused on formulations composed of the protective antigen (PA) adsorbed to aluminum hydroxide. However, due to the labile nature of PA, antigen stability is a primary concern for vaccine development. Thus, there is a need for a delivery system capable of preserving the immunogenicity of PA through all the steps of vaccine fabrication, storage, and administration. In this work, we demonstrate that biodegradable amphiphilic polyanhydride nanoparticles, which have previously been shown to provide controlled antigen delivery, antigen stability, immune modulation, and protection in a single dose against a pathogenic challenge, can stabilize and release functional PA. These nanoparticles demonstrated polymer hydrophobicity-dependent preservation of the biological function of PA upon encapsulation, storage (over extended times and elevated temperatures), and release. Specifically, fabrication of amphiphilic polyanhydride nanoparticles composed of 1,6-bis(p-carboxyphenoxy)hexane and 1,8-bis(p-carboxyphenoxy)-3,6- dioxaoctane best preserved PA functionality. These studies demonstrate the versatility and superiority of amphiphilic nanoparticles as vaccine delivery vehicles suitable for long-term storage

Thresholds for the Oxford Hip Score after total hip replacement surgery:a novel approach to postoperative evaluation

Abstract Background This is a prospective cohort study to define the thresholds to distinguish patients with a satisfactory or unsatisfactory outcome after total hip replacement (THR) based on patient-reported outcome measures (PROMs) including the Oxford Hip Score (OHS), and using patient satisfaction and patient-perceived function as global transition items. The thresholds are intended to be used as a tool in the process of determining which patients are in need of postoperative outpatient evaluation. Methods One hundred and three THR patients who had completed a preoperative questionnaire containing the OHS questionnaire were invited to complete the same questionnaire and supplementary questions at a mean of 6 (4–9) months after surgery. Correlations between outcome measures and anchors were calculated using Pearson’s correlation coefficient. Thresholds were established by receiver operating characteristic (ROC) analysis, using multiple anchors. Results Significant correlations were found between outcome measures and anchors. Thresholds were determined for outcome measures coupled with satisfaction, patient-perceived function and a combination thereof using a cut-off of 50 and 70. Conclusions We have established a set of thresholds for Oxford scores that may help determine which THR patients are in need of postoperative evaluation. These thresholds can be implemented in clinical practice. Level of evidence Level 3