A mathematical model for assessment of material requirements for cable supported bridges: implications for conceptual design

Recent technological developments have led to improvements in the strengths of materials, such as the steel and wire ropes used in the construction of cable supported bridges. This, combined with technological advancements in construction, has encouraged the design of structures with increasing spans, leaving the question of material and environmental costs behind. This paper presents a refined mathematical model for the assessment of relative material costs of the supporting structures for cable-stayed and cable suspension bridges. The proposed model is more accurate than the ones published to date in that it includes the self weight of the cables and the pylons. Comparisons of material requirements for each type of bridge are carried out across a range of span/dip ratios. The basis of comparison is the assumption that each structure is made of the same material (steel) and carries an identical design load, q, exerted by the deck. Calculations are confined to a centre span of a three-span bridge, with the size of the span ranging from 500 m to 3000 m. Results show that the optimum span/dip ratio, which minimises material usage, is 3 for a cable-stayed (harp type) bridge, and 5 for a suspension structure. The inclusion of the self weight of cable in the analysis imposes limits on either the span, or span/dip ratio. This effect is quantified and discussed with reference to the longest cable-supported bridges in the world completed to date and planned in the future

Feasibility of active feedback control of rotordynamic instability

Some of the considerations involved in the use of feedback control as a means of eliminating or alleviating rotordynamic instability are discussed. A simple model of a mass on a flexible shaft is used to illustrate the application of feedback control concepts

Building Middle-Level Mathematics Teachers\u27 Capacities as Teachers and Leaders: The Math in the Middle Institute Partnership

This article describes professional development for middle-level mathematics teachers offered through the Math in the Middle Institute Partnership, a National Science Foundation-funded project to build teachers’ capacities to improve mathematics learning for all students. An overview of the project, including descriptions of its goals and curriculum are provided. Detailed descriptions of two mathematics courses and one pedagogy course are offered. The mathematics courses included here are the introductory course to the Math in the Middle Institute, as well as one of the final math courses of the Institute in which participants apply mathematical knowledge and processes to real-world problems. The pedagogy course features curriculum that enables teachers to acquire an understanding of the nature and purpose of action research, and launches teachers into planning and implementing systematic inquiry in their own mathematics classrooms around topics of their choosing. The varied abilities of teachers, as well as growth in teachers’ mathematical and pedagogical capacities, are represented by several samples of student work provided within the article. In addition, mathematical and pedagogical products of student work are also provided through the project’s URL links. Improving teacher quality is identified as a national need in mathematics education and one many universities and schools across the country are working in partnership to try to address. This article describes a professional development project aimed at improving mathematics teaching and learning in the middle grades. An overview of the project, along with a close look at several of its course offerings, are presented highlighting mathematical and pedagogical goals, challenges, and accomplishments

Barium release system

A chemical system is described for releasing a good yield of free barium neutral atoms and barium ions in the upper atmosphere and interplanetary space for the study of the geophysical properties of the medium. The barium is released in the vapor phase so that it can be ionized by solar radiation and also be excited to emit resonance radiation in the visible range. The ionized luminous cloud of barium becomes a visible indication of magnetic and electrical characteristics in space and allows determination of these properties over relatively large areas at a given time

Rocket having barium release system to create ion clouds in the upper atmosphere

A chemical system for releasing a good yield of free barium atoms and barium ions to create ion clouds in the upper atmosphere and interplanetary space for the study of the geophysical properties of the medium is presented

A study of oxidation kinetics of nickel metal in flowing air and oxygen-nitrogen mixtures

Oxidation kinetics of nickel sheet in flowing air and gas mixture

Understanding Teacher Leadership in Middle School Mathematics: A Collaborative Research Effort

We report findings from a collaborative research effort designed to examine how teachers act as leaders in their schools. We find that teachers educated by the Math in the Middle Institute act as key sources of advice for colleagues within their schools while drawing support from a network consisting of other teachers in the program and university-level advisors. In addition to reporting on our findings, we reflect on our research process, noting some of the practical challenges involved, as well as some of the benefits of collaboration

Whirling of the single mass rotor

Motion equations for whirling mass rotor on damped elastic shaf