Assessment of the operating characteristics of the SSME LOX turbopump pump-end bearing

A bearing/shaft model of the SSME LOX turbopump was developed using the SHABERTH bearing/shaft math modeling computer code. A previously developed bearing/shaft thermal model of the SSME LOX turbopump turbine and bearing was used in conjunction with SHABERTH to evaluate the thermomechanical operating characteristics of the LOX turbopump end bearings. Results show that for the two unmounted diametrical clearances evaluated (4.0 mils and 6.3 mils), the inboard pump end bearing supports about 81% of the isolator load for the small clearance and 77% of the isolator load for the larger clearance. Bearing clearance changes due to thermal effects were 40% for the 4.0 mil diametrical clearance case and 19% for the 6.3 mil clearance case evaluated. The thermal analysis included evaluation of bearing temperatures for a subcooled case and a saturated case. Results indicate that no drastic temperature change occurred between the two cases. Since the rolling element and race surfaces of the subcooled case were at temperatures sufficiently high enough to be vapor blanketed, exceeding saturation temperature at the bearing inlet did not increase surface temperatures greatly

Advanced rocket engine cryogenic turbopump bearing thermal model

A lumped node thermal model was developed representing the Space Shuttle Main Engine (SSME) liquid oxygen (LOX) turbopump turbine end bearings operating in a cryogenically cooled bearing tester. Bearing elements, shaft, carrier, housing, cryogen flow characteristics, friction heat, and fluid viscous energy are included in the model. Heat transfer characteristics for the regimes of forced convection boiling are modeled for liquid oxygen (LOX) and liquid nitrogen (LN2). Large temperature differences between the cryogenic fluid and baring contact surfaces require detailed nodal representation in these areas. Internal loads and friction heat are affected by temperature dependent operating clearances requiring iterations between bearing thermal and mechanical models. Analyses indicate a thermal-mechanical coupling resulting in reduced operating clearances, increased loading and heating which can contribute to premature bearing failure. Contact surfaces operate at temperatures above local saturation resulting in vapor rather than liquid in the contacts, precluding possible liquid film lubrication. Elevated temperatures can reduce lubrication, increase friction, and reduce surface hardness supporting a surface failure mode rather than subsurface fatigue

Stability of hexagonal solidification patterns

We investigate the dynamics of cellular solidification patterns using three-dimensional phase-field simulations. The cells can organize into stable hexagonal patterns or exhibit unsteady evolutions. We identify the relevant secondary instabilities of regular hexagonal arrays and find that the stability boundaries depend significantly on the strength of crystalline anisotropy. We also find multiplet states that can be reached by applying well-defined perturbations to a pre-existing hexagonal array.Comment: Minor changes, mainly in introduction and conclusion, one reference adde

What is Legal Doctrine

Legal doctrine is the currency of the law. In many respects, doctrine is the law, at least as it comes from courts. Judicial opinions create the rules or standards that comprise legal doctrine. Yet the nature and effect of legal doctrine has been woefully understudied. Researchers from the legal academy and from political science departments have conducted extensive research on the law, but they have largely ignored the others’ efforts. Part of the reason for this unfortunate disconnect is that neither has effectively come to grips with the descriptive meaning of legal doctrine. In this article, we attempt to describe the concept of legal doctrine and propound various theories of how legal doctrine may matter in judicial decision making and how those theories may be empirically tested

Judicial Citation to Legislative History: Contextual Theory and Empirical Analysis

Judge Leventhal famously described the invocation of legislative history as the equivalent of entering a crowded cocktail party and looking over the heads of the guests for one\u27s friends. The volume of legislative history is so great and varied, some contend, that judges cite it selectively to advance their policy agendas. In this article, we employ positive political and contextual theories of judicial behavior to examine how judges use legislative history. We consider whether opinion-writing judges, as Judge Leventhal might suggest, cite legislative history from legislators who share the same political-ideological perspective as the opinion-writing judge? Or do judges make such choices in a broader context than Judge Levanthal\u27s statement suggests. We posit that an opinion writing judge would cite legislative statements supporting an outcome preferred by the opinion-writing judge, when such statements come from legislators who share the same political-ideological perspective as the opinion-writing judge\u27s colleagues or superiors. This should be so regardless of whether the cited legislator shares the broader perspectives of the opinion-writing judge himself. Put in Leventhal\u27s terms, instead of looking for their own ideological friends, judges look over the heads of the guests for the legislative friends of the judge\u27s colleagues on the bench (or superiors on higher benches). We test this approach with court opinion data gathered from LEXIS and find evidence of hierarchy (high court oversight) and panel (co-members on a court) effects in citation to legislative history, effects that appear related to the political-ideological identification of judges who review or are co-members on a panel of the authoring judge. Specifically, we find that the higher the proportion of Republicans in the reviewing court or sitting on the same three-judge panel, the higher the proportion of legislative history cites that will be to Republican legislators, independent of the political orientation of the authoring judge

Judicial Citation to Legislative History: Contextual Theory and Empirical Analysis

Judge Leventhal famously described the invocation of legislative history as the equivalent of entering a crowded cocktail party and looking over the heads of the guests for one\u27s friends. The volume of legislative history is so great and varied, some contend, that judges cite it selectively to advance their policy agendas. In this article, we employ positive political and contextual theories of judicial behavior to examine how judges use legislative history. We consider whether opinion-writing judges, as Judge Leventhal might suggest, cite legislative history from legislators who share the same political-ideological perspective as the opinion-writing judge? Or do judges make such choices in a broader context than Judge Levanthal\u27s statement suggests. We posit that an opinion writing judge would cite legislative statements supporting an outcome preferred by the opinion-writing judge, when such statements come from legislators who share the same political-ideological perspective as the opinion-writing judge\u27s colleagues or superiors. This should be so regardless of whether the cited legislator shares the broader perspectives of the opinion-writing judge himself. Put in Leventhal\u27s terms, instead of looking for their own ideological friends, judges look over the heads of the guests for the legislative friends of the judge\u27s colleagues on the bench (or superiors on higher benches). We test this approach with court opinion data gathered from LEXIS and find evidence of hierarchy (high court oversight) and panel (co-members on a court) effects in citation to legislative history, effects that appear related to the political-ideological identification of judges who review or are co-members on a panel of the authoring judge. Specifically, we find that the higher the proportion of Republicans in the reviewing court or sitting on the same three-judge panel, the higher the proportion of legislative history cites that will be to Republican legislators, independent of the political orientation of the authoring judge

Judicial Citation to Legislative History: Contextual Theory and Empirical Analysis

Judge Leventhal famously described the invocation of legislative history as the equivalent of entering a crowded cocktail party and looking over the heads of the guests for one\u27s friends. The volume of legislative history is so great and varied, some contend, that judges cite it selectively to advance their policy agendas. In this article, we employ positive political and contextual theories of judicial behavior to examine how judges use legislative history. We consider whether opinion-writing judges, as Judge Leventhal might suggest, cite legislative history from legislators who share the same political-ideological perspective as the opinion-writing judge? Or do judges make such choices in a broader context than Judge Levanthal\u27s statement suggests. We posit that an opinion writing judge would cite legislative statements supporting an outcome preferred by the opinion-writing judge, when such statements come from legislators who share the same political-ideological perspective as the opinion-writing judge\u27s colleagues or superiors. This should be so regardless of whether the cited legislator shares the broader perspectives of the opinion-writing judge himself. Put in Leventhal\u27s terms, instead of looking for their own ideological friends, judges look over the heads of the guests for the legislative friends of the judge\u27s colleagues on the bench (or superiors on higher benches). We test this approach with court opinion data gathered from LEXIS and find evidence of hierarchy (high court oversight) and panel (co-members on a court) effects in citation to legislative history, effects that appear related to the political-ideological identification of judges who review or are co-members on a panel of the authoring judge. Specifically, we find that the higher the proportion of Republicans in the reviewing court or sitting on the same three-judge panel, the higher the proportion of legislative history cites that will be to Republican legislators, independent of the political orientation of the authoring judge

Judicial Citation to Legislative History: Contextual Theory and Empirical Analysis

Judge Leventhal famously described the invocation of legislative history as the equivalent of entering a crowded cocktail party and looking over the heads of the guests for one\u27s friends. The volume of legislative history is so great and varied, some contend, that judges cite it selectively to advance their policy agendas. In this article, we employ positive political and contextual theories of judicial behavior to examine how judges use legislative history. We consider whether opinion-writing judges, as Judge Leventhal might suggest, cite legislative history from legislators who share the same political-ideological perspective as the opinion-writing judge? Or do judges make such choices in a broader context than Judge Levanthal\u27s statement suggests. We posit that an opinion writing judge would cite legislative statements supporting an outcome preferred by the opinion-writing judge, when such statements come from legislators who share the same political-ideological perspective as the opinion-writing judge\u27s colleagues or superiors. This should be so regardless of whether the cited legislator shares the broader perspectives of the opinion-writing judge himself. Put in Leventhal\u27s terms, instead of looking for their own ideological friends, judges look over the heads of the guests for the legislative friends of the judge\u27s colleagues on the bench (or superiors on higher benches). We test this approach with court opinion data gathered from LEXIS and find evidence of hierarchy (high court oversight) and panel (co-members on a court) effects in citation to legislative history, effects that appear related to the political-ideological identification of judges who review or are co-members on a panel of the authoring judge. Specifically, we find that the higher the proportion of Republicans in the reviewing court or sitting on the same three-judge panel, the higher the proportion of legislative history cites that will be to Republican legislators, independent of the political orientation of the authoring judge

Citation to Legislative History: Empirical Evidence on Positive Political and Contextual Theories of Judicial Decision Making

We present empirical evidence suggesting that political context—judicial hierarchy and judicial panel dynamics—influences an authoring judge’s use of legislative history. Specifically, we find that to the extent that political ideology matters, a district court judge’s choice of legislative history is influenced, albeit mostly, by (1) the political makeup of the overseeing circuit court and (2) the political characteristics of a judge’s panel colleagues, as well as by the circuit court as a whole. These factors matter more than the authoring judge’s own political-ideological connection to the legislators. Put differently, an authoring judge will have a greater tendency to cite legislative history by legislators who share political affiliation with the colleagues and superiors of the authoring judge than legislators sharing the same political party affiliation as the authoring judge himself. These findings are consistent generally with positive political and contextual theories of judicial persuasion, collegiality, and strategic decision making