Preventing broken-rail-caused derailments is a high priority for the rail industry and government. The current practice is to periodically inspect rails using non-destructive technologies such as ultrasonic rail inspection. Determining the optimal inspection frequency is a critical decision in railway infrastructure management. The objective of this paper is to develop an analytical framework t...

The problem of attempting to construct radar signals whose ambiguity functions are sharply peaked in both time and frequency gives rise to a quantitative concept of the irregularity of a distribution of points. The problem of maximizing the irregularity of N points distributed on a bounded closed interval is here examined. A discrete mathematical tool for studying the irregularity function is d...

Rail surface defects such as the abrasion, scratch and peeling often cause damages to the train wheels and rail bearings. An efficient and accurate detection of rail defects is of vital importance for the safety of railway transportation. In the past few decades, automatic rail defect detection has been studied; however, most developed methods use optic-imaging techniques to collect the rail su...

The type and magnitude of loads passing through the track superstructure have a great impact on both the design and the performance of concrete sleepers and fastening systems. To date, the majority of North American research focusing on quantifying rail infrastructure loading conditions has been conducted on heavy-haul freight railroads. However, the results and recommendations from these studi...

Impacts of livestock grazing in arid and semiarid environments are often concentrated in and around wetlands where animals congregate for water, cooler temperatures, and green forage. We assessed the impacts of winter-spring (November-May) cattle grazing on marsh vegetation cover and occupancy of a highly secretive marsh bird that relies on dense vegetation cover, the California Black Rail (Lat...

In this note a new measure of irregularity of a simple undirected graph G is introduced. It is named the total irregularity of a graph and is defined as irrt(G) = 1 2 ∑ u,v∈V (G) |dG(u)− dG(v)| , where dG(u) denotes the degree of a vertex u ∈ V (G). The graphs with maximal total irregularity are determined. It is also shown that among all trees of same order the star graph has the maximal total...

AIMS To determine the ownership and use of various assistive devices by older people living at home. METHOD A random sample of 1405 elderly people aged 65 years and over, in three health authorities, were asked about ownership and use of a number of disability aids, spectacles and hearing aids. RESULTS 74% of respondents owned one or more aid, 97% had spectacles and 16% a hearing aid. The m...

This chapter describes basic logic circuits. This can be seen as largely background material for applications in later chapters in the design of dividers and phase detectors in frequency synthesizers. The types of logic discussed will be CMOS rail-to-rail logic, CMOS current mode logic (CML), bipolar CML, and bipolar emitter coupled logic (ECL). Note that CML is a general term and applies to bo...