18 research outputs found
Space transfer vehicle concepts and requirements study, phase 2
This final report is a compilation of the Phase 1 and Phase 2 study findings and is intended as a Space Transfer Vehicle (STV) 'users guide' rather than an exhaustive explanation of STV design details. It provides a database for design choices in the general areas of basing, reusability, propulsion, and staging; with selection criteria based on cost, performance, available infrastructure, risk, and technology. The report is organized into the following three parts: (1) design guide; (2) STV Phase 1 Concepts and Requirements Study Summary; and (3) STV Phase 2 Concepts and Requirements Study Summary. The overall objectives of the STV study were to: (1) define preferred STV concepts capable of accommodating future exploration missions in a cost-effective manner; (2) determine the level of technology development required to perform these missions in the most cost effective manner; and (3) develop a decision database of programmatic approaches for the development of an STV concept
Rationale and design of the HIP fracture Accelerated surgical TreaTment And Care tracK (HIP ATTACK) Trial : a protocol for an international randomised controlled trial evaluating early surgery for hip fracture patients
© Author(s) (or their employer(s)) 2019. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.Peer reviewedPublisher PD
Strontium Isotopes Test Long-Term Zonal Isolation of Injected and Marcellus Formation Water after Hydraulic Fracturing
One concern regarding unconventional
hydrocarbon production from
organic-rich shale is that hydraulic fracture stimulation could create
pathways that allow injected fluids and deep brines from the target
formation or adjacent units to migrate upward into shallow drinking
water aquifers. This study presents Sr isotope and geochemical data
from a well-constrained site in Greene County, Pennsylvania, in which
samples were collected before and after hydraulic fracturing of the
Middle Devonian Marcellus Shale. Results spanning a 15-month period
indicated no significant migration of Marcellus-derived fluids into
Upper Devonian/Lower Mississippian units located 900–1200 m
above the lateral Marcellus boreholes or into groundwater sampled
at a spring near the site. Monitoring the Sr isotope ratio of water
from legacy oil and gas wells or drinking water wells can provide
a sensitive early warning of upward brine migration for many years
after well stimulation