13,786 research outputs found
GOES-next navigation operations
The next generation of Geostationary Operational Environmental Satellites, GOES-I through -M (hereafter referred to as GOES-Next), begins a new era in the operation of weather satellites by the National Oceanic and Atmospheric Administration (NOAA). With a new spacecraft design, three-axis attitude stabilization, new ground support equipment, and improved methods of image navigation and registration that use on board compensation techniques to correct images for satellite motion, NOAA expects improved performance over the current series of dual-spin spacecraft. To meet these expectations, planning is currently underway for providing the complex and intensive operational environment that will meet the challenge of operating the GOES-Next spacecraft. This paper describes that operational environment
GOES I/M image navigation and registration
Image Navigation and Registration (INR) is the system that will be used on future Geostationary Operational Environmental Satellite (GOES) missions to locate and register radiometric imagery data. It consists of a semiclosed loop system with a ground-based segment that generates coefficients to perform image motion compensation (IMC). The IMC coefficients are uplinked to the satellite-based segment, where they are used to adjust the displacement of the imagery data due to movement of the imaging instrument line-of-sight. The flight dynamics aspects of the INR system is discussed in terms of the attitude and orbit determination, attitude pointing, and attitude and orbit control needed to perform INR. The modeling used in the determination of orbit and attitude is discussed, along with the method of on-orbit control used in the INR system, and various factors that affect stability. Also discussed are potential error sources inherent in the INR system and the operational methods of compensating for these errors
Evaluation of Flow Rate Correction in Water Pipeline Distribution Network by Two Numerical Methods of Solution
This study evaluates flow rate correction and approximate flow rates in loops for three different case studies of closed looped pipe distribution network systems using Hardy Cross and Newton Raphson. Darcy Weisbach head loss equation was also used to account for major losses. Manual calculation was initially done for each case study followed by a C-Sharp programming software which was developed to affirm the manual calculation. For one looped network, head loss around the loop converged from 25.60 m to 0.13 m at the third iteration. The two looped network head loss around each loop converged from 170.97 m and 8.92 m to 0.05 and 0.06 m for Hardy Cross at the sixth iteration while the head loss are 0.88 m and 0.24 m at the fourth iteration for both Hardy Cross and Newton Raphson method while for the three looped network, it has head losses around the three loops converged after the fourth iteration from 0.26, 1.36 and 18.32 m to 0.13, 0.11 and 0.10 m respectively for Hardy Cross at thirditeration while the head losses are 0.03, 0.00 and 0.05 m for Newton Raphson method. Newton Raphson method was found to have a better convergence pattern because it convergences in a uniform manner unlike Hardy Cross method. Also, the program developed gave almost but more accurate results as compared to that of manual calculations with the agreement between them rated at 98%. Some slight differences encountered in the mathematical terms calculated were as a result of some accumulated approximation errors.Keywords: Pipe Distribution Network, Head loss, Convergence, Iteratio
A Racial Impact Analysis of HB 1075/SB 201
The economic and social consequences of untreated (or under-treated) substance abuse among minors are significant. This report provides a racial impact analysis of HB 1075/SB 201, legislation approved in the 2012 General Assembly session that seeks to improve access and use of substance and alcohol services by minors. In short, this policy could go a long way to ensure that families are properly educated about these life-changing (and life-saving) programs; however our analysis raises concerns related to cultural competency that may serve to undermine the legislation’s goal. Virginia is incredibly diverse and its communities vary widely with its assets and risks. In this vein, we offer concrete recommendations to maximize the policy’s racial equity. Our analysis also sheds light on the ongoing challenge Virginia’s state agencies have had to address cultural competency within its services. Additional research is necessary to determine what service gaps may exist, which would increase or decrease the racial equity impact. By answering these questions, Virginia will be better prepared to further reduce alcohol and substance abuse by all minors
Electronic Commerce in the Retail Brokerage Industry: Trading Costs of Internet Versus Full Service Firms
Electronic brokerages on the Internet represent one of the most successful examples of
electronic commerce, having captured over 20% of retail stock trades. According to
economic theory, prices of commodities like securities should converge to one price in a
market with the transparency of the Internet. A review of published commissions for
online brokers shows that this "law of one price" does not appear to hold for the
commissions charged by retail brokers. In this paper we explore one possible explanation
for these differences in commissions. Specifically, we test whether the total cost of
trading, including commissions and savings based on the quality of execution, obeys the
law of one price. In a carefully designed experiment, we simultaneously purchased or
sold 100 share lots of stock using a voice-broker, an expensive online broker and an
inexpensive online broker in each trial. We found relatively few price improvements,
which are a measure of execution quality. The difference among brokers in obtaining
price improvements was not statistically significant. The brokers do exhibit statistically
significant differences in total trading costs; at a volume of 100 shares commission costs
dominate execution quality. We explore the implications of the findings for larger lot
sizes, choosing a broker, and electronic commerce in the brokerage industry.Information Systems Working Papers Serie
Absorption cross section and Hawking radiation in two-dimensional AdS black hole
We calculate the absorption coefficient of scalar field on the background of
the two-dimensional AdS black hole, which is of relevance to Hawking radiation.
For the massless scalar field, we find that there does not exist any massless
radiation.Comment: 6 pages, revtex, no figure
Cognitively-inspired Agent-based Service Composition for Mobile & Pervasive Computing
Automatic service composition in mobile and pervasive computing faces many
challenges due to the complex and highly dynamic nature of the environment.
Common approaches consider service composition as a decision problem whose
solution is usually addressed from optimization perspectives which are not
feasible in practice due to the intractability of the problem, limited
computational resources of smart devices, service host's mobility, and time
constraints to tailor composition plans. Thus, our main contribution is the
development of a cognitively-inspired agent-based service composition model
focused on bounded rationality rather than optimality, which allows the system
to compensate for limited resources by selectively filtering out continuous
streams of data. Our approach exhibits features such as distributedness,
modularity, emergent global functionality, and robustness, which endow it with
capabilities to perform decentralized service composition by orchestrating
manifold service providers and conflicting goals from multiple users. The
evaluation of our approach shows promising results when compared against
state-of-the-art service composition models.Comment: This paper will appear on AIMS'19 (International Conference on
Artificial Intelligence and Mobile Services) on June 2
Linking Community Service, Learning, and Enviromental Analytical Chemistry
In 1994, during a tour of the then-new natural sciences building- a $43 million teaching and research complex fully equipped with the latest in technology and instrumentation for chemistry and geology courses-a member of the Buffalo Public Schools Board of Education asked, How can the community [that paid for it] have access to this teaching and research equipment? That question triggered the effort reported here - a program to better link teaching and research to community service
Synthesis and Biological Evaluation of 5′-O-Dicarboxylic Fatty Acyl Monoester Derivatives of Anti-HIV Nucleoside Reverse Transcriptase Inhibitors
A number of 5′-O-dicarboxylic fatty acyl monoester derivatives of 3′-azido-3′-deoxythymidine (zidovudine, AZT), 2′,3′-didehydro-2′,3′-dideoxythymidine (stavudine, d4T), and 3′-fluoro-3′-deoxythymidine (alovudine, FLT) were synthesized to improve the lipophilicity and potentially the cellular delivery of parent polar 2′,3′-dideoxynucleoside (ddN) analogs. The compounds were evaluated for their anti-HIV activity. Three different fatty acids with varying chain length of suberic acid (octanedioic acid), sebacic acid (decanedioic acid), and dodecanedioic acid were used for the conjugation with the nucleosides. The compounds were evaluated for anti-HIV activity and cytotoxicity. All dicarboxylic ester conjugates of nucleosides exhibited significantly higher anti-HIV activity than that of the corresponding parent nucleoside analogs. Among all the tested conjugates, 5′-O-suberate derivative of AZT (EC50 = 0.10 nM) was found to be the most potent compound and showed 80-fold higher anti-HIV activity than AZT without any significant toxicity (TC50 \u3e500 nM)
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