490 research outputs found
Peracetic Acid Pulping of Aspen Chips
Ten cooks were carried out after an acceptable experimental procedure was found.
The brightness obtained was extremely high when compared to conventional cooks. All cooks gave a very low permanganate number. The yield ranged from 60 percent to 54 percent with 58 to 96 percent peracetic acid on the oven dry weight of the chips
Design and testing of the LITE Variable Field Stop mechanism
The Variable Field Stop (VFS) is a rotary mechanism that reliably positions any of four aperture plates in the optical path of a spaceflight experiment, limiting the amount of light reaching the detectors. This paper discusses the design, operation, and testing of the VFS
Book Reviews
Book Reviews of: Stephen Jay Gould, The Mismeasure of Man (Norton) Saul Bellow, The Dean\u27s December (Harper and Row) John Noble Wilford, The Mapmakers (Alfred Knopf
Entry Descent and Landing Workshop Proceedings
Entry mass at Mars is limited by the payload size that can be carried by a rigid capsule that can fit inside the launch vehicle fairing. Landing altitude at Mars is limited by ballistic coefficient (mass per area) of entry body. Inflatable technologies allow payload to use full diameter of launch fairing, and deploy larger aeroshell before atmospheric interface, landing more payload at a higher altitude. Also useful for return of large payloads from Low Earth Orbit (LEO)
Development and Test Plans for the MSR EEV
The goal of the proposed Mars Sample Return mission is to bring samples from the surface of Mars back to Earth for thorough examination and analysis. The Earth Entry Vehicle is the passive entry body designed to protect the sample container from entry heating and deceleration loads during descent through the Earth s atmosphere to a recoverable location on the surface. This paper summarizes the entry vehicle design and outlines the subsystem development and testing currently planned in preparation for an entry vehicle flight test in 2010 and mission launch in 2013. Planned efforts are discussed for the areas of the thermal protection system, vehicle trajectory, aerodynamics and aerothermodynamics, impact energy absorption, structure and mechanisms, and the entry vehicle flight test
Lunar lander conceptual design
A conceptual design is presented of a Lunar Lander, which can be the primary vehicle to transport the equipment necessary to establish a surface lunar base, the crew that will man the base, and the raw materials which the Lunar Station will process. A Lunar Lander will be needed to operate in the regime between the lunar surface and low lunar orbit (LLO), up to 200 km. This lander is intended for the establishment and operation of a manned surface base on the moon and for the support of the Lunar Space Station. The lander will be able to fulfill the requirements of 3 basic missions: A mission dedicated to delivering maximum payload for setting up the initial lunar base; Multiple missions between LLO and lunar surface dedicated to crew rotation; and Multiple missions dedicated to cargo shipments within the regime of lunar surface and LLO. A complete set of structural specifications is given
Patient-specific dendritic cell vaccines with autologous tumor antigens in 72 patients with metastatic melanoma.
Aim: Metastatic melanoma patients were treated with patient-specific vaccines consisting of autologous dendritic cells loaded with antigens from irradiated cells from short-term autologous tumor cell lines.
Patients & methods: A total of 72 patients were enrolled in a single-arm Phase I/II (NCT00948480) trial or a randomized Phase II (NCT00436930).
Results: Toxicity was minimal. Median overall survival (OS) was 49.4 months; 5-year OS 46%. A 5-year OS was 72% for 18 recurrent stage 3 without measurable disease when treated and 53% for 30 stage 4 without measurable disease when treated. A total of 24 patients with measurable stage 4 when treated (median of four prior therapies) had an 18.5 months median OS and 46% 2-year OS.
Conclusion: This dendritic cell vaccine was associated with encouraging survival in all three clinical subsets. Clinicaltrial.gov NCT00436930 and NCT00948480
Attitude Control Performance of IRVE-3
The Inflatable Reentry Vehicle Experiment 3 (IRVE-3) launched July 23, 2012, from NASA Wallops Flight Facility and successfully performed its mission, demonstrating both the survivability of a hypersonic inflatable aerodynamic decelerator in the reentry heating environment and the effect of an offset center of gravity on the aeroshell's flight L/D. The reentry vehicle separated from the launch vehicle, released and inflated its aeroshell, reoriented for atmospheric entry, and mechanically shifted its center of gravity before reaching atmospheric interface. Performance data from the entire mission was telemetered to the ground for analysis. This paper discusses the IRVE-3 mission scenario, reentry vehicle design, and as-flown performance of the attitude control system in the different phases of the mission
Human Mars Entry, Descent and Landing Architecture Study: Deployable Decelerators
NASAs Entry, Descent and Landing Architecture Study uses a trajectory simulation framework to evaluate various technologies and concepts of operations for human scale EDL at Mars. The study results inform agency technology investments. This paper summarizes the design assumptions and analysis of two deployable entry concepts performed in Phase 2 of the study. The entry concepts include a rigid deployable called the Adaptable Deployable Entry Placement Technology and an inflatable concept called the Hypersonic Inflatable Aerodynamic Decelerator. This paper describes the concept operations of these vehicles to deliver a 20-metric ton payload to the surface of Mars. Details of vehicle design and flight performance are summarized along with results of analysis on the aft body heating and its effect on the payload. Finally, recommended technology investments based on the results are presented
Impact of Vehicle Flexibility on IRVE-II Flight Dynamics
The Inflatable Re-entry Vehicle Experiment II (IRVE-II) successfully launched from Wallops Flight Facility (WFF) on August 17, 2009. The primary objectives of this flight test were to demonstrate inflation and re-entry survivability, assess the thermal and drag performance of the reentry vehicle, and to collect flight data for refining pre-flight design and analysis tools. Post-flight analysis including trajectory reconstruction outlined in O Keefe3 demonstrated that the IRVE-II Research Vehicle (RV) met mission objectives but also identified a few anomalies of interest to flight dynamics engineers. Most notable of these anomalies was high normal acceleration during the re-entry pressure pulse. Deflection of the inflatable aeroshell during the pressure pulse was evident in flight video and identified as the likely cause of the anomaly. This paper provides a summary of further post-flight analysis with particular attention to the impact of aeroshell flexibility on flight dynamics and the reconciliation of flight performance with pre-flight models. Independent methods for estimating the magnitude of the deflection of the aeroshell experienced on IRVE-II are discussed. The use of the results to refine models for pre-flight prediction of vehicle performance is then described
- …