A distributed end-to-end overload control mechanism for networks of SIP servers.

The Session Initiation Protocol (SIP) is an application-layer control protocol standardized by the IETF for creating, modifying and terminating multimedia sessions. With the increasing use of SIP in large deployments, the current SIP design cannot handle overload effectively, which may cause SIP networks to suffer from congestion collapse under heavy offered load. This paper introduces a distributed end-to-end overload control (DEOC) mechanism, which is deployed at the edge servers of SIP networks and is easy to implement. By applying overload control closest to the source of traf?c, DEOC can keep high throughput for SIP networks even when the offered load exceeds the capacity of the network. Besides, it responds quickly to the sudden variations of the offered load and achieves good fairness. Theoretic analysis and extensive simulations verify that DEOC is effective in controlling overload of SIP networks.

Probe-based end-to-end overload control for networks of SIP servers

The Session Initiation Protocol (SIP) has been adopted by the IETF as the control protocol for creating, modifying and terminating multimedia sessions. Overload occurs in SIP networks when SIP servers have insufficient resources to handle received messages. Under overload, SIP networks may suffer from congestion collapse due to current ineffective SIP overload control mechanisms. This paper introduces a probe-based end-to-end overload control (PEOC) mechanism, which is deployed at the edge servers of SIP networks and is easy to implement. By probing the SIP network with SIP messages, PEOC estimates the network load and controls the traffic admitted to the network according to the estimated load. Theoretic analysis and extensive simulations verify that PEOC can keep high throughput for SIP networks even when the offered load exceeds the capacity of the network. Besides, it can respond quickly to the sudden variations of the offered load and achieve good fairness.

An end to support for renewables? The wrong battle to fight. CEPS Commentary, October 2013

On 11 October 2013, the CEOs of 10 large European energy utilities issued a warning that the European energy infrastructure is “in jeopardy” and called for an end to support for renewables on grounds that wind and solar were mature technologies that no longer required such support. Given the unlikelihood, however, that EU decision-makers would renege on their decarbonisation or renewable energy targets, Fabio Genoese asks in this commentary whether it would not be a better strategy for conventional generators to explore new business models built around a ‘reliability pricing system’, in which nearly 100% reliability would be guaranteed for base load but not for peak demand.

A review of human tolerance to side impact. Final report.

National Highway Traffic Safety Administration, Office of Crashworthiness, Washington, D.C.

Response of belted dummy and cadaver to side impact. Final report.

National Highway Traffic Safety Administration, Washington, D.C.

The modernized end-to-end forecast process for quantitative precipitation information : hydrometeorological requirements, scientific issues, and service concepts /

"January 1999."

An end to bugling.

Mode of access: Internet.

End-to-end modelling of the HEG shock tunnel

We demonstrate an end-to-end computational model of the HEG shock tunnel as a way to extract more precise test flow conditions and as a way of getting predictions of new operating conditions. For a selection of established operating conditions, the L1d program was used to simulate the one-dimensional gas-dynamic processes within the whole of the facility. The program reproduces the compression tube performance reliably and, with the inclusion of a loss factor near the upstream-end of the compression tube, it provides a good estimate of the equilibrium pressure in the shock-reflection region over the set of six standard operating conditions for HEG.

Organizing to reorganize:doing end-to-end management in practice

This paper takes a practice perspective on organizing, re-conceptualizing coordination mechanisms as dynamic activities that are under continuous construction and modification in order to socially accomplish intra-organizational relationships and activities. The paper is based on the case of Servico, an organization undergoing a major reorganization of its value chain in response to a change in government regulation. We examine the specific performances through which the ostensive and abstract character of a coordination mechanism, ‘end-to-end management’, is defined and refined into a set of activities that actors can use to effect the re-organization of relationships between two divisions during the delivery of a critical regulatory goal. We find six cycles of iteration between the ostensive and performative nature of end-to-end, which progressively help to organize three phases in the reorganization of Servico; absence, presence and formalization. The discussion examines the processual evolution of these cycles and phases and their implications for the way that reorganization occurred. We draw these findings together in a process model that makes contributions to the literature on organizing, on ostensive and performative routines, and on organizational restructuring.

Organizing to reorganize:doing end-to-end management in practice

This paper takes a practice perspective on organizing, re-conceptualizing coordination mechanisms as dynamic activities that are under continuous construction and modification in order to socially accomplish intra-organizational relationships and activities. The paper is based on the case of Servico, an organization undergoing a major reorganization of its value chain in response to a change in government regulation. We examine the specific performances through which the ostensive and abstract character of a coordination mechanism, ‘end-to-end management’, is defined and refined into a set of activities that actors can use to effect the re-organization of relationships between two divisions during the delivery of a critical regulatory goal. We find six cycles of iteration between the ostensive and performative nature of end-to-end, which progressively help to organize three phases in the reorganization of Servico; absence, presence and formalization. The discussion examines the processual evolution of these cycles and phases and their implications for the way that reorganization occurred. We draw these findings together in a process model that makes contributions to the literature on organizing, on ostensive and performative routines, and on organizational restructuring.

The implementation of a functional query language front-end to a relational database system. Available in 2 volumes.

Database systems have a user interface one of the components of which will normally be a query language which is based on a particular data model. Typically data models provide primitives to define, manipulate and query databases. Often these primitives are designed to form self-contained query languages. This thesis describes a prototype implementation of a system which allows users to specify queries against the database in a query language whose primitives are not those provided by the actual model on which the database system is based, but those provided by a different data model. The implementation chosen is the Functional Query Language Front End (FQLFE). This uses the Daplex functional data model and query language. Using FQLFE, users can specify the underlying database (based on the relational model) in terms of Daplex. Queries against this specified view can then be made in Daplex. FQLFE transforms these queries into the query language (Quel) of the underlying target database system (Ingres). The automation of part of the Daplex function definition phase is also described and its implementation discussed.

End-to-end versus hop-by-hop soft state refresh for multi-hop signalling systems

To ensure state synchronization of signalling operations, many signaling protocol designs choose to establish “soft” state that expires if it is not refreshed. The approaches of refreshing state in multi-hop signaling system can be classified as either end-to-end (E2E) or hop-by-hop (HbH). Although both state refresh approaches have been widely used in practical signaling protocols, the design tradeoffs between state synchronization and signaling cost have not yet been fully investigated. In this paper, we investigate this issue from the perspectives of state refresh and state removal. We propose simple but effective Markov chain models for both approaches and obtain closed-form solutions which depict the state refresh performance in terms of state consistency and refresh message rate, as well as the state removal performance in terms of state removal delay. Simulations verify the analytical models. It is observed that the HbH approach yields much better state synchronization at the cost of higher signaling cost than the E2E approach. While the state refresh performance can be improved by increasing the values of state refresh and timeout timers, the state removal delay increases largely for both E2E and HbH approaches. The analysis here shed lights on the design of signaling protocols and the configuration of the timers to adapt to changing network conditions.