Advanced Software for Analysis of High-Speed Rolling-Element Bearings

COBRA-AHS is a package of advanced software for analysis of rigid or flexible shaft systems supported by rolling-element bearings operating at high speeds under complex mechanical and thermal loads. These loads can include centrifugal and thermal loads generated by motions of bearing components. COBRA-AHS offers several improvements over prior commercial bearing-analysis programs: It includes innovative probabilistic fatigue-life-estimating software that provides for computation of three-dimensional stress fields and incorporates stress-based (in contradistinction to prior load-based) mathematical models of fatigue life. It interacts automatically with the ANSYS finite-element code to generate finite-element models for estimating distributions of temperature and temperature-induced changes in dimensions in iterative thermal/dimensional analyses: thus, for example, it can be used to predict changes in clearances and thermal lockup. COBRA-AHS provides an improved graphical user interface that facilitates the iterative cycle of analysis and design by providing analysis results quickly in graphical form, enabling the user to control interactive runs without leaving the program environment, and facilitating transfer of plots and printed results for inclusion in design reports. Additional features include roller-edge stress prediction and influence of shaft and housing distortion on bearing performance

Field repetition and local mapping in the hippocampus and medial entorhinal cortex

Hippocampal place cells support spatial cognition and are thought to form the neural substrate of a global 'cognitive map'. A widely held view is that parts of the hippocampus also underlie the ability to separate patterns, or to provide different neural codes for distinct environments. However, a number of studies have shown that in environments composed of multiple, repeating compartments, place cells and other spatially modulated neurons show the same activity in each local area. This repetition of firing fields may reflect pattern completion, and may make it difficult for animals to distinguish similar local environments. In this review we will (a) highlight some of the navigation difficulties encountered by humans in repetitive environments, (b) summarise literature demonstrating that place and grid cells represent local and not global space, and (c) attempt to explain the origin of these phenomena. We argue that the repetition of firing fields can be a useful tool for understanding of the relationship between grid cells in the entorhinal cortex and place cells in the hippocampus, the spatial inputs shared by these cells, and the propagation of spatially-related signals through these structures

From Pabst to Pepsi: The Deinstitutionalization of Social Practices and the Creation of Entrepreneurial Opportunities

In this paper, we examine the dual role that social movement organizations can play in altering organizational landscapes by undermining existing organizations and creating opportunities for the growth of new types of organizations. Empirically, we investigate the impact of a variety of tactics employed by the Woman’s Christian Temperance Union (WCTU), the leading organizational representative of the American temperance movement, on two sets of organizations: breweries and soft drink producers. By delegitimating alcohol consumption, altering attitudes and beliefs about drinking, and promoting temperance legislation, the WCTU contributed to brewery failures. These social changes, in turn, created opportunities for entrepreneurs to found organizations producing new kinds of beverages by creating demand for alternative beverages, providing rationales for entrepreneurial action, and increasing the availability of necessary resources.Tolbert13_From_Pabst_to_Pepsi.pdf: 3878 downloads, before Oct. 1, 2020

Dragline roller track improvement. Volume I. Evaluation of low hardness dragline track materials in rolling contact. Final report, September 30, 1976-July 30, 1980

The Franklin Research Center (FRC), a Division of the Franklin Institute, was contracted by the Bureau of Mines to improve walking dragline roller tracks. The contract was subsequently transferred to the Department of Energy. The period from September 1977 to September 1978 covered laboratory rolling contact rig tests to evaluate typical low hardness dragline track materials. The results of this work are covered by DOE/ET/9121-1 Final Report, Volume I. The period from September 1978 to July 1980 covered field measurements of dragline roller circle loadings. The results of this work are covered by DOE/ET/9121-2 Final Report, Volume II. The laboratory rolling contact rig test results indicate that forged vacuum degassed air melt steel materials are recommended over air-melt cast materials for rollers and tracks. The steels tested exhibited good freedom from sensitivity to stress raisers like brinell marks and small holes or discontinuities (Volume I). The largest unknown in a recommended method for life testing roller tracks is the condition of the upper rotating frame structure and the lower tub supporting structure

Dragline roller track improvement. Volume 2. Field measurement of dragline roller circle loading. Final report, September 30, 1976-July 30, 1980

The period from September 1977 to September 1978 covered laboratory rolling contact rig tests to evaluate typical low hardness dragline track materials. The results of this work are covered by DOE/ET/9121-1 Final Report, Volume I. The period from September 1978 to July 1980 covered field measurements of dragline roller circle loadings. The results of this work are covered by DOE/ET/9121-2 Final Report, Volume II. During May 1979, a field test group visited the Beltona Mines in Warrior, Alabama, for the purpose of instrumenting and testing dragline roller circle loading. This testing was done both before and after the introduction of elastomeric padding between the upper track and rotating frame. The data collected indicates installation of an elastomeric pad between the rotation frame and the upper track reduced the strain in the upper track. The primary reason for these load and strain reductions was added flexibility provided by the elastomeric pad coupled with redistribution of local loads. Installation of the elastomeric pad also reduced the peak roller loads resulting from hard spots due to dragline construction. More field data is necessary to fully appreciate the positive and negative effects of elastomeric pad on roller track loading. This information can be obtained through more thorough testing and instrumentation program