Advances in Switched-Mode Power Conversion Part I

A new concept in the design of switched-mode power conversion circuitry is presented. Because of its extreme simplicity, flexibility, and efficiency, it has the potential to replace some conventional electrical power processing methods currently in use. A thorough discussion of the background, development, and operation of the ?uk converter and several of its extensions is included. The coupled-inductor technique further improves efficiency and reduces size and weight. The basic converter and its extensions to two-quadrant and four-quadrant operation are attractive for many applications, i.e., solar (dc) to utility line (ac) power conversion, variable speed dc or ac motor drives, switching power supplies, uninterruptible power supplies, and many others.     

Two Algorithms for Determining the Most Reliable Path of a Network

This paper presents two algorithms for determining the most reliable paths of a communication network, taking into account both the reliabilities of nodes and links. A network is modeled by a linear graph. The first algorithm adapts a node labeling scheme; second is based on the shortest-path matrix algorithm. Both algorithms can be applied to oriented and nonoriented nonsymetric networks. The numerical examples confirm that both algorithms efficiently handle networks with hundreds of nodes and edges. The total amount of computation, expressed by the number of multiplications and comparisons, increases in the labeling procedure with the square of the number of nodes, and in the matrix method with the cube of the number of nodes.     

Development of new models for the estimation of deformation moduli in rock masses based on in situ measurements

Bulletin of Engineering Geology and the Environment - Knowledge of the deformation properties of the rock mass is essential for the stress–strain analysis of structures such as dams, tunnels,...     

New 32-QAM trellis codes for fading channels

The authors propose some new 32-QAM trellis codes for fading channels and examine the performance. The results show that the proposed codes achieve significant improvements relative to the known 32-QAM trellis codes.<>     

Design and performance analysis of the algorithms for channelallocation in cellular networks

The authors consider the problem of dynamic channel allocation in cellular networks. Each cell can use any channel, subject to the interference constraints. Channel allocation algorithms are executed by the network switch in a centralized way. The authors show how to design and use objective functions aimed at proper channel allocation and improvement of network performance. As a figure of merit of network performance, they consider the blocking probability in the network as a whole, and the maximum blocking probability in any particular cell of the network (“hot-spot” in the network). They designed three specific channel allocation policies, based on three different objective functions. Compared with two other benchmark policies, the approach shows significant improvement. Performance analysis of various channel allocation policies is virtually impossible without simulations, which are prohibitively time-consuming in the case of small blocking probabilities. The authors propose an original approximate method based on a short simulation and an analytic approximation. The method exhibits good accuracy and significant improvement in efficiency     

Space-time trellis codes for 8-PSK with two, three and fourtransmit antennas in quasi-static flat fading channels

Good 8-PSK space-time trellis codes (STTCs) for two, three and four transmit antennas are reported and the performance is evaluated by simulation. The new STTCs with three and four transmit antennas achieve large performance improvements over those with two transmit antennas     

Epidemiology of accidental home fires in Montreal2

Accidental home fires usually start in areas of the dwelling where people spend most of their time. The most frequent causes of fires are related to the activities of the residents, smoking being the most common. Persons who have home fires are, on average, younger than their controls, have more children, smoke in bed more and stay at home less often during the day. Typically, they live in apartment buildings where there has already been a fire, have less space available, but enjoy more fire protection than the controls. Home fires have characteristic seasonal, weekly and hourly distributions, as well as preponderance for older areas of the city. They are usually discovered by residents, smoke leading to detection in most cases, and most often occupants use their own telephones to alert firemen. This happens “immediately” after the discovery and the firemen are at the scene within 10 minutes in 90% of all instances. Extent of damage seems to be dependant on the time that elapses between the onset and the discovery of fires. No single variable can explain the occurences of accidental home fires. Yet, there appears to exist a person-building susceptible profile in which personal characteristics take precedence. Smoke detectors should become mandatory. Anti-smoking efforts should be enhanced. More care is needed when designing electrical power supplies in dwellings.