Public reporting burden for the collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing the collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing this burden, to Washington Headquarters Services, Directorate for Information Operations and Reports, 1215 Jefferson Davis Highway, Suite 1204, Arlington VA 22202-4302. Respondents should be aware that notwithstanding any other provision of law, no person shall be subject to a penalty for failing to comply with a collection of information if it does not display a currently valid OMB control number. The original document contains color images. ABSTRACTDespite its vital importance to the welfare and security of the nation, the Global Positioning System (GPS) constellation is populated with numerous satellites operating well beyond their design life. These aging satellites are more likely to malfunction, which can reduce service coverage, degrade accuracy, and in some cases, transmit dangerously inaccurate data. The Air Force currently subscribes to a launch to sustain (LTS) GPS satellite replenishment strategy. Under this strategy, new satellites are launched only after a satellite failure or just prior to a failure. The purpose of this monograph is to investigate whether the Air Force should forgo its LTS replenishment strategy in favor of a more aggressive launch to augment (LTA) strategy in order to proactively replace high-risk satellites and to accelerate modernization timelines. It will be shown that the explosive growth of GPS over the past fifteen years has outpaced the Air Force's strategy on satellite replenishment. The growing importance of GPS must be matched with a progressive replenishment strategy that sustains its reliability and improves its utility for military, civil, and commercial users. The LTS strategy has placed a disproportionate emphasis on operational efficiency at the expense of operational effectiveness and has impaired the timely insertion of critical new capabilities into the constellation. A LTA strategy would help to reverse this trend. The Global Positioning System (GPS) has become a vital component to both the military and civilian infrastructures. U.S. military forces have evolved from using its signal for routine navigation to depending on it for nearly every facet of combat operations. GPS is also seamlessly integrated into every major civil infrastructure, including transportation, communications, energy, commerce, banking, and emergency response services. In addition, the accuracy and worldwide availability of GPS has spawned a multi-billion dollar international market representing billions of dollars in annual tax revenue.Despite its vital importance, the GPS constellation is populated with numerous satellites operating well beyond their design life. These agin...
No abstract
The Valley Transit Authority is working with the Bay Area Rapid Transit (BART) to ultimately expand BART's existing light rail system south to San Jose. Several new stations are proposed as part of the Light Rail Track extension. However, two of the new stations will impact two existing large diameter water pipelines, owned by the Santa Clara Valley Water District. These existing lines have to be relocated away from the new stations. This paper will discuss the technical design aspects of installing new pipe and fittings into an existing 66" concrete pressure pipe raw water main and into an existing 42" steel pipe treated water main in order to properly relocate both lines. A key consideration in this modification to the existing lines is the thrust forces generated from the realignment. The thrust restraint of the old 66" line posed a number of challenges since the original pipe in this area did not have longitudinal thrust forces. Additionally the owner, the Santa Clara Valley Water District, has their own specialized thrust restraint procedure that is based on a 1960s paper. This approach is different than what is recommended by the AWWA in the pertinent AWWA design manuals. Other challenges encountered during the relocation design included a number of pipe design considerations such as internal and external load, buckling, and fittings design. Further complicating the relocation effort is the need to account for a special "rattle box" casing to protect existing gas lines under a new "floating slab" for the Light Rail Track at one location. Included in the discussion will be recommendations on a few "lessons learned" from the relocation design efforts. BACKGROUND
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