72 research outputs found
Proactive TCP mechanism to improve Handover performance in Mobile Satellite and Terrestrial Networks
Emerging standardization of Geo Mobile Radio (GMR-1) for satellite system is
having strong resemblance to terrestrial GSM (Global System for Mobile
communications) at the upper protocol layers and TCP (Transmission Control
Protocol) is one of them. This space segment technology as well as terrestrial
technology, is characterized by periodic variations in communication properties
and coverage causing the termination of ongoing call as connections of Mobile
Nodes (MN) alter stochastically. Although provisions are made to provide
efficient communication infrastructure this hybrid space and terrestrial
networks must ensure the end-to-end network performance so that MN can move
seamlessly among these networks. However from connectivity point of view
current TCP performance has not been engineered for mobility events in
multi-radio MN. Traditionally, TCP has applied a set of congestion control
algorithms (slow-start, congestion avoidance, fast retransmit, fast recovery)
to probe the currently available bandwidth on the connection path. These
algorithms need several round-trip times to find the correct transmission rate
(i.e. congestion window), and adapt to sudden changes connectivity due to
handover. While there are protocols to maintain the connection continuity on
mobility events, such as Mobile IP (MIP) and Host Identity Protocol (HIP), TCP
performance engineering has had less attention. TCP is implemented as a
separate component in an operating system, and is therefore often unaware of
the mobility events or the nature of multi-radios' communication. This paper
aims to improve TCP communication performance in Mobile satellite and
terrestrial networks.Comment: 5 pages, 2 figure
Imperatives and Challenges of Resource Description and Access (RDA) Implementation in Libraries in a Developing Country
In recent times, information products are becoming more often packaged and repackaged in electronic formats. Cataloguing these resources is a core responsibility of libraries and librarians. A major emerging standardization tool for cataloguing electronic resources is the âresource description and accessâ (RDA). This article examined the imperatives of RDA implementation among libraries in a developing countryâNigeria. It reviewed global trends and observed the poor RDA implementation level among libraries in Nigeria. It also identified challenges of RDA implementation peculiar to a developing country like Nigeria. The article further outlined strategies that would help to deal with the identified challenges. It concluded that the implementation of RDA is not optional, but mandatory for Nigerian libraries if they must be and remain relevant in the competitive world of librarianship
Quantifying Assurance in Learning-enabled Systems
Dependability assurance of systems embedding machine learning(ML)
components---so called learning-enabled systems (LESs)---is a key step for
their use in safety-critical applications. In emerging standardization and
guidance efforts, there is a growing consensus in the value of using assurance
cases for that purpose. This paper develops a quantitative notion of assurance
that an LES is dependable, as a core component of its assurance case, also
extending our prior work that applied to ML components. Specifically, we
characterize LES assurance in the form of assurance measures: a probabilistic
quantification of confidence that an LES possesses system-level properties
associated with functional capabilities and dependability attributes. We
illustrate the utility of assurance measures by application to a real world
autonomous aviation system, also describing their role both in i) guiding
high-level, runtime risk mitigation decisions and ii) as a core component of
the associated dynamic assurance case.Comment: Author's pre-print version of manuscript accepted for publication in
the Proceedings of the 39th International Conference in Computer Safety,
Reliability, and Security (SAFECOMP 2020
Rectification of ârestrained vs unrestrainedâ
For furnace testing of fireâresistant floor and roof assemblies in the United States, the ASTM E 119 standard (and similarly the UL 263 standard) permits two classifications for boundary conditions: ârestrainedâ and âunrestrained.â When incorporating tested assemblies into an actual structural system, the designer, oftentimes a fire protection or structural engineer, must judge whether a ârestrainedâ or âunrestrainedâ classification is appropriate for the application. It is critical that this assumption be carefully considered and understood, as many qualified listings permit a lesser thickness of applied fire protection for steel structures (or less concrete cover for concrete structures) to achieve a certain fire resistance rating if a ârestrainedâ classification is confirmed, as compared with an âunrestrainedâ classification. The emerging standardization of structural fire engineering practice in the United States will disrupt centuryâlong norms in the manner to which structural behavior in fire is addressed. For instance, the current edition of the ASCE/SEI 7 standard will greatly impact how designers consider restraint. Accordingly, this paper serves as an exposĂ© of the ârestrained vs unrestrainedâ paradigm in terms of its paradoxical nature and its controversial impact on the industry. More importantly, potential solutions toward industry rectification are provided for the first time in a contemporary study of this paradigm
Correlation, price discovery and co-movement of ABS and equity
Asset-backed securitization (ABS) has become a viable and increasingly attractive risk management and refinancing method either as a standalone form of structured finance or as securitized debt in Collateralized Debt Obligations (CDO). However, the absence of industry standardization has prevented rising investment demand from translating into market liquidity comparable to traditional fixed income instruments, in all but a few selected market segments. Particularly low financial transparency and complex security designs inhibits profound analysis of secondary market pricing and how it relates to established forms of external finance. This paper represents the first attempt to measure the intertemporal, bivariate causal relationship between matched price series of equity and ABS issued by the same entity. In a two-dimensional linear system of simultaneous equations we investigate the short-term dynamics and long-term consistency of daily secondary market data from the U.K. Sterling ABS/MBS market and exchange traded shares between 1998 and 2004 with and without the presence of cointegration. Our causality framework delivers compelling empirical support for a strong co-movement between matched price series of ABS-equity pairs, where ABS markets seem to contribute more to price discovery over the long run. Controlling for cointegration, risk-free interest and average market risk of corporate debt hardly alters our results. However, once we qualify the magnitude and direction of price discovery on various security characteristics, such as the ABS asset class, we find that ABS-equity pairs with large-scale CMBS/RMBS and credit card/student loan ABS reveal stronger lead-lag relationships and joint price dynamics than whole business ABS. JEL Classifications: G10, G12, G2
Experience in the exploitation of a large control system
Experience of a four-year exploitation of the large control system of the CERN PS accelerator complex is presented with special emphasis on the parameters which are very sensitive to the exploitation team productivity. The software tools suite used in this daily maintenance is described and a particular analysis of the power and benefits of advance software technology used for the architecture of this suite is explained. The integration of this suite in the Control System is presented, as well as its use in the Control System development phase. Some considerations of the potential benefit of an Object Oriented equipment access are outlined
Accelerating transition to virtual research organisation in social science (AVROSS) : final report
This report is the fourth deliverable of the AVROSS study (Accelerating Transition to Virtual Research Organisation in Social Science, AVROSS).
The study aims were to identify the requirements and options for accelerating the transition from traditional research to virtual research organisations through e-Infrastructures. The reason for this focus is that it is clear that "soft" sciences have both much to gain and a key role to play in promoting e-Infrastructure uptake across the disciplines, but to date have not been the fastest adopters of advanced grid-based e-Infrastructure. Our recommendations to EU policy-makers can be expected to point the way to changing this situation, promoting e-Infrastructure in Europe in these disciplines, with clear requirements to developers and expected impact in several other disciplines with related requirements, such as e-Health
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