We describe a process algebraic approach to the semantics of replicated systems. We extend a subset of CCS with a replication operator to model systems with replicated synchronous majority voting. Based on an operational semantics, we de ne a bisimulation semantics. As the bisimulation semantics does not characterise fault tolerance we de ne preorders which introduces a hierarchy of faulty proc...

This topic discusses the application of digital-control to DC/DC-switching converters and how to model the digitally controlled system. The main blocks that appear in almost every digital controller—the error ADC, the compensator, and the digital PWM engine—are discussed and used to model small-signal characteristics such as frequency response, stability criteria, the effects of quantization, a...

The discussions and prototyping carried out during RLG Digital Image Access Project (DIAP) suggest a new data model for the bibliographic control of and access to digital image collections, one based on current, standard cataloging practice but enlarged to incorporate the additional detail, hierarchy, and version information needed to adequately describe digital collections. Though not addresse...

Electronic communication technologies continue to change the landscape of reference services. For many users, virtual communication is the preferred means of conversing. Synchronous virtual reference, similar to other synchronous means of communication, is an important method for reaching students and for providing teaching and learning opportunities. Grounded Theory (GT) research provides a me...

This article analyses the challenges and tasks of Digital Library. Focus on the library’s internal IT support management and based on the example of Fudan University, the author gives E-Support concept and divides the IT support architecture of digital library into three levels: the reader service and management platform, the library staff IT service platform and the technician service and mana...

Viterbi decoders are widely used in digital communication which dissipates huge quantity of power. High speed and low power of system can be achieved by applying asynchronous technique to the digital system. In this work we have designed VD with 4-state, 1/2-code rate synchronous and asynchronous Viterbi decoder. Dynamic power can be lower by reducing switching activity and this is occurring du...

Rapid Single Flux Quantum (RSFQ) logic is a superconducting digital circuit technology that has emerged as a possible alternative to advanced semiconductor technologies for large scale ultra-high speed, very low power digital applications. Timing of RSFQ circuits at frequencies of tens to hundreds of gigahertz is a challenging and still unresolved problem. In many circuit topologies of current ...

This paper introduces an approach to near timeoptimal control for synchronous buck dc–dc converters. The proposed proximate time-optimal digital (PTOD) controller is a combination of a constant-frequency pulsewidth modulation (PWM) controller employing a linear PID compensator close to a reference point, and a linear or nonlinear switching surface controller (SSC) away from the reference, toget...

Silicon technologies advances brought the possibility of integrating billions of transistors in a VLSI die. However, as these transistors become smaller due to fabrication method enhancements, some aspects that were negligible in older technologies emerge as difficulties for the design in current and future technology nodes. In this context, fully synchronous digital circuits become harder to b...