A creep cavity growth model for creep-fatigue life prediction of a unidirectional W/Cu composite

A microstructural model was developed to predict creep-fatigue life in a (0)(sub 4), 9 volume percent tungsten fiber-reinforced copper matrix composite at the temperature of 833 K. The mechanism of failure of the composite is assumed to be governed by the growth of quasi-equilibrium cavities in the copper matrix of the composite, based on the microscopically observed failure mechanisms. The methodology uses a cavity growth model developed for prediction of creep fracture. Instantaneous values of strain rate and stress in the copper matrix during fatigue cycles were calculated and incorporated in the model to predict cyclic life. The stress in the copper matrix was determined by use of a simple two-bar model for the fiber and matrix during cyclic loading. The model successfully predicted the composite creep-fatigue life under tension-tension cyclic loading through the use of this instantaneous matrix stress level. Inclusion of additional mechanisms such as cavity nucleation, grain boundary sliding, and the effect of fibers on matrix-stress level would result in more generalized predictions of creep-fatigue life

Tax‐Exempt Hospitals’ Investments in Community Health and Local Public Health Spending: Patterns and Relationships

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/139924/1/hesr12739-sup-0001-AppendixSA1.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/139924/2/hesr12739_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/139924/3/hesr12739.pd

The Process of Control Design for the NASA Langley Minimast Structure

he NASA Langley Minimast Facility is an experimental flexible structure designed to emulate future large space structures. The Minimast system consists of a 18 bay, 20 meter-long truss beam structure which is cantilevered at its base from a rigid foundation. It is desired to use active control to attenuate the response of the structure at bay 10 and 18 due to impulse disturbances at bay 9 while minimizing actuator torque commanded from the torque wheel actuators. This paper details the design process used to select sensors for feedback and performance weights on the Minimast facility. Initially, a series of controllers are synthesized using H2 optimal control techniques for the given structural model, a variety of sensor locations and performance criteria to determine the "best" displacement sensor and/or accelerometers to be used for feedback. Upon selection of the sensors, controllers are formulated to determine the affect of using a reduced order model of the Minimast structure instead of the higher order structural analysis model for control design and the relationship between the actuator torque level and the closed-loop performance. Based on this information, controllers are designed using μ-synthesis techniques and implemented on the Minimast structure. Results of the implementation of these controllers on the Minimast experimental facility are presented

The Polarized Spectrum of Apm 08279+5255

We report the discovery of significant linear polarization (p > 1%) in the hyperluminous z=3.87 BALQSO APM~08279+5255. The polarization spectrum is complex, with properties similar to those of other, lower redshift but more highly polarized BALQSOs. The resonance emission lines are unpolarized while the absorption troughs show polarization similar to or higher than the continuum. In particular, an apparent increase of polarization in the trough covering 1000-1030 angstroms (rest) supports the interpretation of this feature as a broad absorption component associated with OVI/Ly_beta local to the QSO, as opposed to an intervening damped Ly_alpha absorption system. The elevated polarization in some of the absorption features implies that we view the scattered (polarized) spectrum through a sightline with less absorbing material than the direct spectrum. Therefore, the complex structure of the polarization spectrum in this brilliant lensed BALQSO suggests that it will be an important laboratory for studying the structure of QSOs at high redshift.Comment: 8 pages, 1 figure. Accepted for publication in The Astrophysical Journal Letter

ESTABLISHING POPULATION AND INDIVIDUAL BIOEQUIVALENCE CONFIDENCE INTERVALS

Average bioequivalence is used to assess pharmacokinetic properties of proposed generic drug before they are marketed. The limitations of average bioequivalence have led the U.S. Food and Drug Administration to propose the use of popUlation bioequivalence and individual bioequivalence. In this study, bootstrap confidence intervals were used to evaluate population bioequivalence and individual bioequivalence in the context of a 2 x 4 crossover experimental design. Two bioequivalence criteria were compared: the mean-squared difference criterion and a probability-based criterion. Simulations were conducted to study the properties of the bootstrap confidence intervals under each criterion in establishing population bioequivalence or individual bioequivalence. Various inter-subject, within-subject, and subject-by-formulation interaction variance components were considered

A promessa de Kalamazoo e sua interpretação: mudanças no clima escolar

The Kalamazoo Promise was announced in the fall of 2005, offering free college tuition at any public state college or university for graduates of the district who have gained acceptance to a postsecondary institution. This program was funded through the generous support of anonymous donors, and a federally-funded evaluation is underway to examine potential changes that result from its implementation. This paper situates perceptions of school climate in this moment of punctuated equilibrium of school reform, and in the context of this universal postsecondary scholarship program. This evaluation research draws from multiple data sources including interviews with educators, and surveys and interviews with students in the school district. Findings indicate that school climate has improved since the announcement of the program. We discuss the implications of research findings and the potential of the Kalamazoo Promise as a catalyst for systemic change in the district.La promesa de Kalamazoo se anunci en el otoo 2005, ofreciendo educacin universitaria gratuita en cualquier universidad pblica del estado a graduados del distrito que fueran aceptados en una universidad. Este programa fue financiado a travs de la apoyo de donantes annimos. Una evaluacin de los fondos federales est en marcha con el objetivo para verificar los posibles cambios que resulten de su implementacin. Este artculo presenta las percepciones del ambiente escolar en este particular punto de equilibrio de la reforma escolar, y en el contexto de este programa universal de becas universitarias. Esta investigacin de evaluacin utiliz mltiples fuentes de datos, incluyendo entrevistas con docentes, as como cuestionarios y entrevistas con estudiantes en distritos escolares. Los resultados indican que el clima escolar ha mejorado desde el inicio de la ejecucin del programa. Discutimos las implicaciones potenciales de los resultados de la Promesa Kalamazoo como un catalizador para el cambio sistmico en el distrito.A Promessa Kalamazoo foi anunciada no outono de 2005, oferecendo educao universitria gratuita em qualquer faculdade pblica do estado para graduados da regio que haviam recebido aceitao de uma instituio universitria. Tal programa foi financiado atravs do apoio de doadores annimos. Uma avaliao de financiamento federal est em andamento com o objetivo de verificar mudanas potenciais que resultam de sua implementao. O artigo apresenta percepes de clima escolar neste momento especfico de equilbrio da reforma escolar, bem como no contexto deste programa universal de bolsa universitria. Esta pesquisa de avaliao parte de mltiplas fontes de dados, incluindo entrevista com professores, alm de questionrios e entrevistas com alunos nas escolas distritais. Resultados indicam que o clima escolar melhorou desde o incio/implementao do programa. Discutimos as implicaes dos resultados e o potencial da Promessa Kalamazoo como catalisador para mudanas sistmicas na regio

The Cool ISM in Elliptical Galaxies. II. Gas Content in the Volume - Limited Sample and Results from the Combined Elliptical and Lenticular Surveys

We report new observations of atomic and molecular gas in a volume limited sample of elliptical galaxies. Combining the elliptical sample with an earlier and similar lenticular one, we show that cool gas detection rates are very similar among low luminosity E and SO galaxies but are much higher among luminous S0s. Using the combined sample we revisit the correlation between cool gas mass and blue luminosity which emerged from our lenticular survey, finding strong support for previous claims that the molecular gas in ellipticals and lenticulars has different origins. Unexpectedly, however, and contrary to earlier claims, the same is not true for atomic gas. We speculate that both the AGN feedback and merger paradigms might offer explanations for differences in detection rates, and might also point towards an understanding of why the two gas phases could follow different evolutionary paths in Es and S0s. Finally we present a new and puzzling discovery concerning the global mix of atomic and molecular gas in early type galaxies. Atomic gas comprises a greater fraction of the cool ISM in more gas rich galaxies, a trend which can be plausibly explained. The puzzle is that galaxies tend to cluster around molecular-to-atomic gas mass ratios near either 0.05 or 0.5.Comment: 37 pages, including 4 tables and 12 figures. Accepted for publication in the Astrophysical Journa

Cross-Sectional Assessment of Safety Culture Perceptions and Safety Behavior in Collegiate Aviation Programs in the United States

A cross-sectional quasi- mixed-method approach was used to determine the relationships between safety culture perceptions and safety reporting behavior among flight students with and without certified flight instructor (CFI) ratings. Respondents (n=259) were recruited from five collegiate aviation programs in the US and took part in the study. Survey Items adopted from the Collegiate Aviation Perception of Safety Culture Assessment Survey (CAPSCAS) were validated using factor analysis analyzed for reliability before use in the study. Researchers sought to find out if the safety reporting behavior (reporting frequency) of respondents could be predicted from their safety culture perceptions. Pearson’s Bivariate Correlation, Multiple Regressions, independent T-test of means, and Analysis of Covariance were used for data analyses. The findings indicated that the age of respondents, perceptions on the variables Reporting System and Safety Fundamentals were statistically significant predictors of safety reporting behavior. Additionally, there was no significant statistical difference in the mean safety reporting frequency between respondents with and without CFI ratings. A major theme from the qualitative part of the study was pressure to fly when conditions were considered unsafe, in order to meet ground course targets. These respondents felt that such pressures placed them under duress to fly when not fully fit psychologically, physiologically, and in adverse weather conditions. The inclusion of the collegiate program’s safety reporting process and procedures in a related academic course like Safety Management Systems (SMS) was found to be very beneficial in some collegiate programs. Researchers of this study recommend an extension of safety awareness programs to include all line personnel, students, and management involved in collegiate aviation programs. The awareness program must entail the process and procedures for effective safety reporting. Additionally, further validation of the CAPSCAS should be conducted. Qualitative approaches can be effectively utilized to gain a clearer understanding of safety culture perceptions, specifically, how age influences safety reporting behavior. Furthermore, analysis of safety culture perceptions among groups such as flight program management personnel and flight students can be compared and contrasted. These recommendations may assist the collegiate aviation community to enhance a positive organizational safety culture

An Examination of the Relationships between Safety Culture Perceptions and Safety Reporting Behavior among Non-Flight Collegiate Aviation Majors

Some collegiate aviation programs in the United States have adopted the voluntary Safety Management System (SMS) strongly advocated by the Federal Aviation Administration to build a proactive safety culture. While relevant safety culture research has primarily focused on flight personnel, there has been limited investigation on non-flight collegiate aviation majors (collegiate air traffic control, aviation management, and unmanned aerial systems students) perceptions on collegiate aviation safety. This study examined the relationship between safety culture perceptions and safety reporting behavior of non-flight major students at five collegiate aviation programs. One hundred and sixteen completed responses to a validated safety culture perception survey instrument were used for analysis (n = 116). The findings suggest an unfavorable perception on the Response and Feed-back scale and may indicate challenges with effective feedback from safety professionals for reports on safety issues made by respondents. The strong correlation between the perceptions of respondents on the reporting system and response and feed-back amplifies a need for greater diligence in providing feed-back to safety issues reported in collegiate aviation programs. A causal path analysis with mediating variables suggests the need for collegiate aviation management to provide resources that align safety performance indicators with safety objectives. The researchers recommend effective safety promotional programs that will improve the safety culture perceptions of non-flight aviation students