Attrition rate of iron ore in the gas-solid fluidized beds with the wide size distribution

The effects of superficial gas velocity (Ug = 1.25 – 3.00 m/s) and distributor hole size (8.0 – 12.4 mm) on the attrition rate of iron ore in a gas-solid fluidized bed with 0.076 m ID ´ 3.7 m height with or without circulation were investigated. The particle density and the Sauter mean diameter of fresh iron ore were 3,705 kg/m3 and 357 m, respectively. When the kinetic energy rate from the orifice was equal or greater than 180 J/s, the trend of attrition rate could be determined. The attrition rate was determined by measuring the fractional mass of fine particle formation (- 500 m fraction) during 30 min without circulation. In experiments with circulation, the attrition rate was determined by measuring a different threshold size, 63 m. The attrition rate increases with increasing kinetic energy rate from the orifice (J/s). The kinetic energy rate from the orifice was calculated using the mass flow rate and orifice nozzle velocity. The correlation of attrition rate with the kinetic energy rate from the orifice was. When the bed height rapidly decreased below the jet length under very severe conditions, the attrition rate did not follow the correlation

The attrition rate of licensed chiropractors in California: an exploratory ecological investigation of time-trend data

<p>Abstract</p> <p>Background</p> <p>The authors hypothesized the attrition rate of licensed chiropractors in California has gradually increased over the past several decades. "Attrition" as determined for this study is defined as a loss of legal authority to practice chiropractic for any reason during the first 10 years after the license was issued. The percentage of license attrition after 10 years was determined for each group of graduates licensed in California each year between 1970 and 1998. The cost of tuition, the increase in the supply of licensed chiropractors and the ratio of licensed chiropractors to California residents were examined as possible influences on the rate of license attrition.</p> <p>Methods</p> <p>The attrition rate was determined by a retrospective analysis of license status data obtained from the California Department of Consumer Affairs. Other variables were determined from US Bureau of Census data, survey data from the American Chiropractic Association and catalogs from a US chiropractic college.</p> <p>Results</p> <p>The 10-year attrition rate rose from 10% for those graduates licensed in 1970 to a peak of 27.8% in 1991. The 10-year attrition rate has since remained between 20-25% for the doctors licensed between 1992-1998.</p> <p>Conclusions</p> <p>Available evidence supports the hypothesis that the attrition rate for licensed chiropractors in the first 10 years of practice has risen in the past several decades.</p

Attrition rates among student nurses at the Gondar college of medical sciences

Abstract: A retrospective analysis of academic performance of nursing students was done. From the 402 students admitted from 1984 to 1991, 267 (66.4%) graduated. The attrition rate showed an increase from 15.2% to 45.4%. Higher attrition rate (51.3%) was reported for females as compared to males (21.9%). No correlation between ESLCE result and academic performance was detected (r = 0.01) .The use of multiple admission criteria, increasing the duration of training and improving the learning environment are some of the recommendations suggested based on the study. [Ethiop. J. Health Dev. 1995;9(2):87-90

IMPROVED AMORPHOUS SOLID DISPERSION PERFORMANCE USING BINARY POLYMER COMBINATIONS

With increasing attrition rate of new molecular entities due to sub-optimum aqueou

The Individual Blood Cell Telomere Attrition Rate Is Telomere Length Dependent

Age-associated telomere shortening is a well documented feature of peripheral blood cells in human population studies, but it is not known to what extent these data can be transferred to the individual level. Telomere length (TL) in two blood samples taken at ∼10 years interval from 959 individuals was investigated using real-time PCR. TL was also measured in 13 families from a multigenerational cohort. As expected, we found an age-related decline in TL over time (r = –0.164, P<0.001, n = 959). However, approximately one-third of the individuals exhibited a stable or increased TL over a decade. The individual telomere attrition rate was inversely correlated with initial TL at a highly significant level (r = –0.752, P<0.001), indicating that the attrition rate was most pronounced in individuals with long telomeres at baseline. In accordance, the age-associated telomere attrition rate was more prominent in families with members displaying longer telomeres at a young age (r = –0.691, P<0.001). Abnormal blood TL has been reported at diagnosis of various malignancies, but in the present study there was no association between individual telomere attrition rate or prediagnostic TL and later tumor development. The collected data strongly suggest a TL maintenance mechanism acting in vivo, providing protection of short telomeres as previously demonstrated in vitro. Our findings might challenge the hypothesis that individual TL can predict possible life span or later tumor development

Utilizing Resilience and Persistence Strategies to Reduce African American Doctoral Attrition

The purpose of this qualitative phenomenological study is to explore the attrition rate of African American doctoral students and how to improve their retention and graduation using resilience and persistence. Across all disciplines, 40–60% of students who began doctoral programs did not persist to graduation (Falconer & Djokic, 2019; Mirick & Wladkowski, 2020). A semi-structured interview format was used to collect the data from 27 African American participants, 20 females and 7 males, who had already obtained their doctoral degrees. The study sought to explain the phenomenon of African American doctoral students who persevered to finish their degree, in spite of the overwhelming statistical attrition rate before them, and to identify the strategies they used to pull them through. The findings suggest African American doctoral students overwhelmingly relied on three strategies, time management, consistent communication with mentors/professors, and cohort/student support to push through their doctoral journey successfully. In addition, 81% of the participants, at one point or another, considered dropping out, a rate higher than the current attrition rate of 40–60%. The study provides recommendations for higher learning institutions, mentors, and students

Factors influencing attrition among learners : Faculty of Applied Social Sciences in OUM

This study examined factors affecting the attrition rate among learners in Open and Distance Learning (ODL) institution. The main focus of the study is to explore what factors cause the attrition, and what are the best ways or strategies to prevent the attrition rate among adult learners. There were 15 adult learners from the Faculty of Applied and Social Sciences (FASS) at Open University Malaysia (OUM) were taken from the population of dormant learners which were not registered for three concurrent semesters. The study found that the main factor of attrition was learners were overextended with too many responsibilities. The three ways to prevent attrition among learners were learners’ communication, learners’ mentoring, and learners’ awareness. It is recommended that the best practice for prevention learners’ attrition was learner itself. This study offered two benefits, factors affecting the attrition rate among adult learners and offered some ways in preventing attrition among adult learners from learners’ own perspective. Therefore, this study can be used as a benchmark for the faculty to handle the attrition cases for adult learners in open and distance learning institutions. (Abstract by author

Methodology of mechanical characterization of coated spherical materials

The aim of this work was to develop a methodology for the mechanical characterization of catalyst beads with a core-shell structure and more especially for coated spherical granules. Supports composed of an alpha alumina core coated by gamma alumina shell were shaped by pan coating to this purpose. The proposed methodology started with the characterization of the microstructure of the coating and the highlight of potential macro defects within. Thereafter three tests simulating mechanical stress, such as impact, compression (bulk crushing test), and shear (drum attrition test) are used. The operational parameters of these tests were also optimised in order to stress preferentially the shell of the coated materials. Among the evaluated tests, drum attrition seems to be most efficient for characterizing coated spherical granules

Explicit Analytical Expression for a Lanchester Attrition-Rate Coefficient for Bonder and Farrell’s m-Period Target-Engagement Policy

Working Paper #5, DTRA Project, July 9, 2001The purpose of this working paper is to give an explicit analytical expression for a Lanche s- ter-type attrition-rate coefficient for direct-fire combat in a heterogeneous-target environment with serial acquisition of targets for Bonder and Farrell’s m-period target-acquisition policy1. It develops this result (its main result) from Taylor’s [2001d] new important general result (that does not depend on the target-engagement policy of a firer type or even on the particulars of the target-acquisition process) for a Lanchester attrition-rate coefficient for serial acquisition by developing explicit ana- lytical expressions for the two key intermediate quantities on which the coefficient depends: namely, (1) expected time to acquire a target that will be engaged, (2) next-target-type-to-be-engaged probability. An analytical expression for the former quantity (the expect value) was recently developed by one of the authors (Taylor [2001e]), while the paper at hand develops such an expression for the latter probability. These two new important intermediate results have allowed us to develop the explicit analytical expression for a Lanchester attrition-rate coefficient for Bonder and Farrell’s target- acquisition policy via Taylor’s general expression for direct-fire combat in a heterogeneous-target environment with serial acquisition of targets. These analytical results are then verified against simulation results