Maintaining consistency in distributed systems

In systems designed as assemblies of independently developed components, concurrent access to data or data structures normally arises within individual programs, and is controlled using mutual exclusion constructs, such as semaphores and monitors. Where data is persistent and/or sets of operation are related to one another, transactions or linearizability may be more appropriate. Systems that incorporate cooperative styles of distributed execution often replicate or distribute data within groups of components. In these cases, group oriented consistency properties must be maintained, and tools based on the virtual synchrony execution model greatly simplify the task confronting an application developer. All three styles of distributed computing are likely to be seen in future systems - often, within the same application. This leads us to propose an integrated approach that permits applications that use virtual synchrony with concurrent objects that respect a linearizability constraint, and vice versa. Transactional subsystems are treated as a special case of linearizability

Options for reshaping the railway

In many countries the mismatch between what the railways offer and what the customers want has caused significant economic inefficiency and severe financial strains for the railways and their government owners. The concept of the railway as a monolithic entity is so strong in many countries as to be a roadblock against reshaping the railway. The authors explore four options which can be used to reshape the railways. First is the lines of business option which improves accountability and responsiveness to markets. The second is the competitive access option which introduces intramodal competition in selected markets, while maintaining unitary control over most railway operations. The third is the"wholesaler"option which would accomplish an excellent marketing job, but the actual operation would remain in monolithic hands. Finally there is the"toll rail enterprise"option which comes closest to reflecting a theoretical model of marketing effectiveness, however it would generate potential operating conflicts and higher transaction costs. The authors show that one generalization holds true in all circumstances: a monolithic railway does not function well in a market economy in competition with privately owned, properly regulated competitors - especially trucking. The authors point out that solutions will vary, but the universal objective as an economy becomes more market driven is to make the railway more market sensitive.Railways Transport,Roads&Highways,Environmental Economics&Policies,Banks&Banking Reform,ICT Policy and Strategies

Asset management and governance: an analysis of fleet management process issues in an asset-intensive organization

Efficient asset management is a key performance driver for asset-intensive organizations. Achieving high utilization and return on investment on physical assets are central corporate objectives for public and private organisations alike. Current approaches on asset management include the engineering and governance perspectives. Both perspectives offer valuable but incomplete insights on the management of asset performance: experience demonstrates that an exclusive focus on one or the other may lead to sub-optimal asset and organizational performance. In this paper, we investigate how an integrated approach to asset management can be constructed in the context of vehicle fleets. Beginning with an analysis of how the asset management process is operated through the asset lifecycle, we identify key engineering and organizational factors influencing asset performance. The relationships between factors are analyzed to provide an integrated fleet asset management approach

Barriers to industrial energy efficiency: a literature review

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Privatisation and Franchising of British Train Operations: the decline and derailment of the Great North Eastern Railway

As a result of the 1993 Railways Act, the British railways industry was privatised which resulted in the separation of ownership and control of the railway infrastructure (track, signals and stations) from that of passenger train operations. The Great North Eastern Railway (GNER), a major train operator, was unable to meet its contractual obligations shortly after successfully re-tendering for its second franchise. Within the context of incomplete contract theory, this paper discusses the main problems inherent in the franchising process and which specifically contributed to the collapse of GNER. In particular, the paper argues that the fragmented structure of asset ownership, the lack of coordination and investment incentives and flaws in the franchise method itself explain the demise of GNER and have undermined the general objectives of railway privatisation

Real Estate Equity Investments and the Institutional Lender: Nothing Ventured, Nothing Gained

We consider a setup in which the channel from Alice to Bob is less noisy than the channel from Eve to Bob. We show that there exist encoding and decoding which accomplish error correction and authentication simultaneously; that is, Bob is able to correctly decode a message coming from Alice and reject a message coming from Eve with high probability. The system does not require any secret key shared between Alice and Bob, provides information theoretic security, and can safely be composed with other protocols in an arbitrary context

From FPGA to ASIC: A RISC-V processor experience

This work document a correct design flow using these tools in the Lagarto RISC- V Processor and the RTL design considerations that must be taken into account, to move from a design for FPGA to design for ASIC