Automatic software upgrades for distributed systems

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2004.Includes bibliographical references (p. 156-164).Upgrading the software of long-lived, highly-available distributed systems is difficult. It is not possible to upgrade all the nodes in a system at once, since some nodes may be unavailable and halting the system for an upgrade is unacceptable. Instead, upgrades may happen gradually, and there may be long periods of time when different nodes are running different software versions and need to communicate using incompatible protocols. We present a methodology and infrastructure that address these challenges and make it possible to upgrade distributed systems automatically while limiting service disruption. Our methodology defines how to enable nodes to interoperate across versions, how to preserve the state of a system across upgrades, and how to schedule an upgrade so as to limit service disrup- tion. The approach is modular: defining an upgrade requires understanding only the new software and the version it replaces. The upgrade infrastructure is a generic platform for distributing and installing software while enabling nodes to interoperate across versions. The infrastructure requires no access to the system source code and is transparent: node software is unaware that different versions even exist. We have implemented a prototype of the infrastructure called Upstart that intercepts socket communication using a dynamically-linked C++ library. Experiments show that Upstart has low overhead and works well for both local-area-and Internet systems.by Sameer Ajmani.Ph.D

Automatic performance optimisation of component-based enterprise systems via redundancy

Component technologies, such as J2EE and .NET have been extensively adopted for building complex enterprise applications. These technologies help address complex functionality and flexibility problems and reduce development and maintenance costs. Nonetheless, current component technologies provide little support for predicting and controlling the emerging performance of software systems that are assembled from distinct components. Static component testing and tuning procedures provide insufficient performance guarantees for components deployed and run in diverse assemblies, under unpredictable workloads and on different platforms. Often, there is no single component implementation or deployment configuration that can yield optimal performance in all possible conditions under which a component may run. Manually optimising and adapting complex applications to changes in their running environment is a costly and error-prone management task. The thesis presents a solution for automatically optimising the performance of component-based enterprise systems. The proposed approach is based on the alternate usage of multiple component variants with equivalent functional characteristics, each one optimized for a different execution environment. A management framework automatically administers the available redundant variants and adapts the system to external changes. The framework uses runtime monitoring data to detect performance anomalies and significant variations in the application's execution environment. It automatically adapts the application so as to use the optimal component configuration under the current running conditions. An automatic clustering mechanism analyses monitoring data and infers information on the components' performance characteristics. System administrators use decision policies to state high-level performance goals and configure system management processes. A framework prototype has been implemented and tested for automatically managing a J2EE application. Obtained results prove the framework's capability to successfully manage a software system without human intervention. The management overhead induced during normal system execution and through management operations indicate the framework's feasibility

Remote hearing aid fitting

Includes abstract.Includes bibliographical references.Hearing aid fitting is a costly process due to the cost of hearing aids, audiologists' hourly rates, and large travelling distances caused by regionally sparse audiologist populations. This dissertation is focused on the development of a system which aims at reducing the severity of this problem

Utilising artificial neural networks (ANNs) towards accurate estimation of life-cycle costs for construction projects

This study aimed to establish a new model of Life Cycle Cost (LCC) for construction projects using Artificial Neural Networks (ANNs). Survey research and Costs Significant Items (CSIs) methods were conducted to identify the most important cost and non-cost factors affecting the estimation of LCC. These important factors are considered as input factors of the model. The results indicated that neural network models were able to estimate the cost with an average accuracy between 91%-95%

Accident Investigation and Learning to Improve Safety Management in Complex System: Remaining Challenges: Proceedings of the 55th ESReDA Seminar

Accident investigation and learning from events are fundamental processes in safety management, involving technical, human, organisational and societal dimensions. The European Safety, Reliability and Data Association, ESReDA, has a long tradition in gathering together experts in the field to work together, and to share and explore experiences of using various paradigms, approaches, methods databased and implementation of safety systems across different industries. The 55th ESReDA seminar on “Accident Investigation and Learning to Improve Safety Management in Complex System: Remaining Challenges” attracted more than 80 participants from industry, authorities, operators, research centres and academia. The seminar programme consisted of 22 technical papers, three keynote speeches and a workshop to debate about the remaining challenges of accident investigation and potential innovative breakthroughs.JRC.G.10-Knowledge for Nuclear Security and Safet

An evaluation of architects' readiness for conducting energy modelling using BIM tools to achieve high energy performance buildings in the UK and Canada

Buildings, consume more than 30% of the world's energy and is the world's largest energyconsuming sector, contributing nearly a quarter of the total global greenhouse gas emissions.Global warming is the result of emission of greenhouse gases, and this represents a significantexistential crisis. The effective design of buildings is one way to mitigate this issue and thisstarts with the design of the building. One of the architect's main responsibilities is thebuilding’s geometric design, which has a considerable impact on energy consumption.Building Performance Analysis (BPA) is generally conducted during the later design stagesoften in support of the mechanical and electrical design, such as heating and cooling systems.To achieve a High Energy Performance Building (HEPB), this research considers thepotential impact and implementation of a process which might bring the geometric designstage and energy analysis stages closer to each other. While architects usually deal withgeometrical design, much of energy performance analysis work is carried out by consultantenergy specialists. However, new BIM tools have the potential to make this stage of analysismore accessible to architects, who may not have specific building physics knowledge.The purpose of this study is to assess the acceptability of BIM based energy analysis tools toarchitects and assess their potential use in early stage energy analysis undertaken by nonspecialist architects. The aim of this research is to evaluate the conditions of the designprocess for HEPB in the UK and Canada and develop a series of recommendations to betterenable architects to address energy efficiency in the early stages of the design process byusing BIM tools.An abductive research approach is used to test existing theories regarding the ability of BIMto design and analyse green buildings. The survey of UK and Canadian architects identifiesissues such as; standards, underlying knowledge, client demand and the use of BIM tools toidentify applicability of the approach. The results from the study are used to understand theprocesses of HEPBs architectural design, including the sources and tools which are used. Therespondents’ familiarity with BIM, its tools and ability for doing tasks in the design andconstruction industry, specifically regarding HEPBs design and the potential barriers foremploying BIM are also considered.The recognised gap in the knowledge is to develop a better understanding of the issues of thedetachment of architects as first designers of buildings involved in geometrical design fromthe later stages (Building Performance Analysis) and the possible solutions that might beprovided by BIM tools. The contribution to knowledge of the research focuses around a betterunderstanding of the specific barriers for the implementation and use of BIM energy analysistools by architectural practices which will be achieved through finding weaknesses in thecurrent process of design process and discovering potential solutions

Earth resources technology satellite operations control center and data processing facility. Book 2 - Systems studies Final report

Systems analysis for ERTS NASA Data Processing Facility system and subsystem

Predictive testing and clinical genetic counselling services for Huntington disease in the Western Cape : an evaluation over eleven years

Includes bibliographical references (leaves 273-325)