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This paper aims to demonstrate the benefits of using different impeder materials for induction tube welding systems.

To show the difference in using various impeder materials, a new approach was taken to model tube welding systems in two and three dimensions. Three-dimensional (3-D) electromagnetic models were used to determine the current distribution along the weld vee as well as the permeability of the tube along the length of the welding system. Two-dimensional (2-D) coupled electromagnetic plus thermal models with rotational movement were used to determine the temperature distribution in the heat-affected zone.

Simulation results suggest upwards of 25 per cent system power savings when using a soft magnetic composite (SMC) impeder rather than the traditional ferrites.

There is currently a lack of experimental data to validate the models, but future work will include comparison of models to real-world trials.

When dealing with tube welding systems, there are possibilities to improve process efficiency or increase production quality and output by improving the impeder material.

While simulations of tube welding systems have been done previously, studies on improving impeder materials are rarely carried out. This paper brings to light possible improvements to be made to induction tube welding systems.

Effect of unstable “wavy” temperature distribution on the part surface during the process of induction heating of ferromagnetic materials was observed and reported by two Russian scientists in 1940 (Babat and Lozinskii, 1940). They reported that under certain conditions, one can observe periodical or quasi-periodical bright stripes on the part surface when its temperature passes through the Curie point. In time, these stripes expand and merge, forming a normal temperature pattern. They called this phenomenon “polosatiy nagrev” (striation heating). Let us call it the “zebra effect” for simplicity. It can exist for a relatively long time, from several seconds to several tens of seconds. Several explanations of the zebra effect were proposed with not very convincing arguments. The purpose of this study is to improve the understanding of this effect.

Wider spreading of induction technology and use of computer simulation of induction processes create a demand and open new possibilities for study of the zebra effect. This study provides an overview of the available information about the zebra effect and gives new explanation of this phenomenon based on existing experimental data and new results of simulation. Conditions for zebra occurrence and its technological importance or limitations are discussed.

Computer simulation using the Flux 2D program allows to demonstrate the striation (zebra) effect that can appear in the process of heating magnetic materials and reproduce main experimental findings related to this effect. Simulation provides a great opportunity to investigate the zebra phenomenon in virtual reality, providing qualitatively correct results. Results of simulation show that the zebra effect can appear in a relatively narrow range of material properties and operating conditions. The main factor is a big enough gradient of permeability near the Curie point. At present, it is difficult to expect high quantitative accuracy of simulation due to multiple assumptions in simulation algorithms and insufficient or inaccurate information about the material properties near the Curie point.

Several explanations of the zebra effect were proposed with not very convincing arguments. There were concerns that the zebra effect could set significant limits on the use of induction heating for surface hardening due to non-uniform temperature distribution along the part (Babat and Lozinskii, 1940; Babat, 1965; Lozinskii, 1949, 1969). However, it did not happen. There were no complaints from scientists or practitioners regarding any negative effect of the zebra phenomenon. Moreover, the authors of this paper did not find any original publications on this issue for more than half a century. Only few old induction experts confirm that they observed the zebra effect or something similar, whereas a great majority of induction community members never heard about it.

This presentation is a continuation of the presentation made at IHS 98. The topics remain the same; however, the content is updated to reflect the improvements in both computer software and hardware and some new studies made by Centre for Induction Technology, Inc. (CIT). Several examples are presented that show the results of computer simulation studies and their verification by means of empirical studies. These examples include 1‐D, 2‐D and 3‐D computer simulation of various induction heating systems. Special attention is paid to 3‐D electromagnetic simulation, including a fundamental study of the end and edge effects for induction heating of slabs and the historical perspective of this case.

The US General Services Administration (GSA) sought to identify innovative and best practices in real property management at the state level, with the intent that sharing these practices may lead to creative new approaches throughout all levels of government. The resulting study focused on four aspects of real property management and identified the following states as exemplars: (1) Acquisition and construction (Maryland, Minnesota, Utah) (2) Operations and maintenance (Michigan, Missouri, Utah) (3) Web‐enabled software (Texas, Washington) (4) Public‐private partnerships (Arizona, Washington) Many of these best practices have resulted in streamlined operations, cost savings, and innovative solutions to complex problems. They offer new ideas for real property management. In order to perform the study, GSA contracted with George Washington (GW) University. The GSA study team included the following members: Marjorie Lomax, Director of the Evaluation and Outreach Division, Andrea Wohlfeld Kuhn, Project Team Leader, and team members Dennis Goldstein, Sheldon Greenberg,Robert Harding, Jonathan Herz and Rebekah Pearson. The GW team was under the direction of Dr Kathryn Newcomer, PhD, Principal Investigator, with Robin Kane and Howard Smith as Research Associates. The following paper is an excerpt of the study. The entire document can be downloaded at http://www.gsa.gov/statesrpbp

Interest in developing institutional explanations of political and economic behavior has blossomed among social scientists since the early 1980s. Three intellectual perspectives are now prevalent: rational choice theory, historical institutionalism and a new school of organizational analysis. This paper summarizes, compares and contrasts these views and suggests ways in which cross‐fertilization may be achieved. Particular attention is paid to how the insights of organizational analysis and historical institutionalism can be blended to provide fruitful avenues of research and theorizing, especially with regard to the production, adoption, and mobilization of ideas by decision makers.

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Current US tax laws provide investors an incentive to time the sales of their bonds to minimize tax liability. This gives rise to a tax-timing option that affects bond value. In reality, corporate bond investors’ tax-timing strategy is complicated by risk of default. Existing term structure models have ignored the effect of the tax-timing option, and how much corporate bond value is due to the tax-timing option is unknown. In this chapter, we assess the effects of taxes and stochastic interest rates on the timing option value and equilibrium price of corporate bonds by considering discount and premium amortization, multiple trading dates, transaction costs, and changes in the level and volatility of interest rates. We find that the value of the tax-timing option accounts for a substantial proportion of corporate bond price even when interest rate volatility is low. Ignoring the timing option value results in overestimation of credit spread, and underestimation of default probability and the marginal investor’s income tax rate. These estimation biases generally increase with bond maturity and credit risk.