The effect of prewhirl on the internal aerodynamics and performance of a mixed flow research centrifugal compressor

The internal three-dimensional steady and time-varying flow through the diffusing elements of a centrifugal impeller were investigated using a moderate scale, subsonic, mixed flow research compressor facility. The characteristics of the test facility which permit the measurement of internal flow conditions throughout the entire research compressor and radial diffuser for various operating conditions are described. Results are presented in the form of graphs and charts to cover a range of mass flow rates with inlet guide vane settings varying from minus 15 degrees to plus 45 degrees. The static pressure distributions in the compressor inlet section and on the impeller and exit diffuser vanes, as well as the overall pressure and temperature rise and mass flow rate, were measured and analyzed at each operating point to determine the overall performance as well as the detailed aerodynamics throughout the compressor

Firm level factors that affect returns to real estate investment trusts

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Urban Studies and Planning, 2000.Includes bibliographical references (leaves 72-73).This thesis examines the historical financial data for publicly traded securities issued by Real Estate Investment Trusts (REITS). The inquiry isolates certain quantifiable firm specific financial data and organizes that data into pooled, time-series cross-sections. Annual returns to capital are determined for certain equity REITS from 1990 to 1999 and are used as the dependent variable in a statistical regression analysis. The analysis includes independent variables drawn from a database and includes variables to adjust results for the impact of macroeconomic factors. In addition, indexes for the broader markets are identified and included in the regressions to adjust for the impact of trends in the general market. Following adjustments for macroeconomic factors and general market trends the regression results identify various firm specific variables that display a statistically significant relationship to relative returns to capital in REIT securities over time. Negative impacts on returns are observed for increases in firm size and for certain debt features such as variable rate debt, unsecured debt, and total debt. Positive impacts on returns are associated with higher levels of asset growth as well as relatively higher levels of secured debt and preferred stock. The expected positive correlation of returns with increases in broader stock market indexes and negative correlation with increasing short-term interest rates is not displayed. For the period from 1993 to 1999, the data indicate an inverse correlation of REIT returns to the stock market as represented by the S&P 500 index and a direct relation with short-term interest rates. Interpretations of the results are provided in a form that relates the firm level determinates of returns to capital with the history of REITS and their organizational and tax characteristics. Alternatives for further inquiry are identified and implications for investors and REIT managers are discussed.by William B. Strange, III and Duo Tang.S.M

NASA MSFC hardware in the loop simulations of automatic rendezvous and capture systems

Two complementary hardware-in-the-loop simulation facilities for automatic rendezvous and capture systems at MSFC are described. One, the Flight Robotics Laboratory, uses an 8 DOF overhead manipulator with a work volume of 160 by 40 by 23 feet to evaluate automatic rendezvous algorithms and range/rate sensing systems. The other, the Space Station/Station Operations Mechanism Test Bed, uses a 6 DOF hydraulic table to perform docking and berthing dynamics simulations

Pennsylvania Folklife Vol. 30, No. 2

• A Search for the Origin of the Pennsylvania Barn • A Forebay Bank Barn in Texas • The Swiss Bank House Revisited: Messerschmidt-Dietz Cabin • Paul R. Wieand, Lehigh County Folk Artist • Aldes un Neies / Old & Newhttps://digitalcommons.ursinus.edu/pafolklifemag/1090/thumbnail.jp

Analytical techniques and the Air Force logistics readiness officer

The accelerated globalization of logistics activities over the last several decades has spurred a rapid expansion of port facilities all cross the world. However, the recent slowdown of international trade, coupled with a global financial crisis, has created an on-going glut of international port facilities throughout the world. Although the abundance of port facilities provides more transshipment options for carriers and shippers, it makes the port selection decision more complex and difficult. To cope with this new set of challenges, this paper proposes a hybrid data envelopment analysis (DEA)/ analytic hierarchy process (AHP) model that is designed to identify factors specifically influencing transshipment port selection, evaluates the extent of influence of those factors on a transshipment port selection decision, and then determines the most critical ones among various factors. To illustrate the usefulness of the proposed hybrid DEA/AHP model, major container hub ports in Far-East Asia were analyzed

Rose-Ringed Parakeets

Rose-ringed parakeets (Psittacula krameri; hereafter RRPA; Figure 1) are an invasive species in the United States, present in Alabama, Louisiana, Texas, and Virginia, and with established populations in California, Florida, and Hawaii. They are also the most successful species of invasive parakeet, worldwide. RRPA can cause significant damage to agriculture, including grains, oilseeds, fruits, and ornamental plants. Large flocks of RRPA roost near human infrastructure resulting in concerns about human health and safety (e.g., collisions with aircraft, disease transmission, feces accumulation, and noise complaints). The population growth and spread of RRPA is of conservation concern given the potential impact on native wildlife, spread of invasive plant seeds, and destruction of native plants. RRPA are an agricultural pest with a generalist diet and feeding behaviors that increase the severity of crop damage (Figure 2). RRPA damage corn by feeding on the anthers and pollen of the inflorescence, the tender cob stage, and the milky cob stage up until maturity. RRPA perch on sunflower heads and access the seeds that are hulled prior to consumption. Damage to tree fruits is greater on the top branches compared to the side and bottom branches. RRPA attack stored grains and eat unripe fruit, extending the damage period. RRPA often discard partially-eaten food. Crop damage varies with some fields experiencing more damage due to the timing of crop maturity or location (e.g., field or orchard edges have greater damage than interior). RRPA strip roosting trees (e.g., royal palms in Kauai) of their leaves. A long-term management plan that involves sustained lethal control is necessary to reduce invasive RRPA populations and their damage. In the meantime, the following damage management methods may provide short-term relief from RRPA damage

Bone mineral density and risk of heart failure in older adults: The Cardiovascular Health Study

Background Despite increasing evidence of a common link between bone and heart health, the relationship between bone mineral density ( BMD ) and heart failure ( HF ) risk remains insufficiently studied. Methods and Results We investigated whether BMD measured by dual‐energy x‐ray absorptiometry was associated with incident HF in an older cohort. Cox models were stratified by sex and interactions of BMD with race assessed. BMD was examined at the total hip and femoral neck separately, both continuously and by World Health Organization categories. Of 1250 participants, 442 (55% women) developed HF during the median follow‐up of 10.5 years. In both black and nonblack women, neither total hip nor femoral neck BMD was significantly associated with HF ; there was no significant interaction by race. In black and nonblack men, total hip, but not femoral neck, BMD was significantly associated with HF , with evidence of an interaction by race. In nonblack men, lower total hip BMD was associated with higher HF risk (hazard ratio, 1.13 [95% CI, 1.01–1.26] per 0.1 g/cm 2 decrement), whereas in black men, lower total hip BMD was associated with lower HF risk (hazard ratio, 0.74 [95% CI, 0.59–0.94]). There were no black men with total hip osteoporosis. Among nonblack men, total hip osteoporosis was associated with higher HF risk (hazard ratio, 2.83 [95% CI, 1.39–5.74]) compared with normal BMD . Conclusions Among older adults, lower total hip BMD was associated with higher HF risk in nonblack men but lower risk in black men, with no evidence of an association in women. Further research is needed to replicate these findings and to study potential underlying pathways. </jats:sec

Field responsive mechanical metamaterials.

Typically, mechanical metamaterial properties are programmed and set when the architecture is designed and constructed, and do not change in response to shifting environmental conditions or application requirements. We present a new class of architected materials called field responsive mechanical metamaterials (FRMMs) that exhibit dynamic control and on-the-fly tunability enabled by careful design and selection of both material composition and architecture. To demonstrate the FRMM concept, we print complex structures composed of polymeric tubes infilled with magnetorheological fluid suspensions. Modulating remotely applied magnetic fields results in rapid, reversible, and sizable changes of the effective stiffness of our metamaterial motifs

Evidence of a Large Novel Gene Pool Associated with Prokaryotic Genomic Islands

Microbial genes that are “novel” (no detectable homologs in other species) have become of increasing interest as environmental sampling suggests that there are many more such novel genes in yet-to-be-cultured microorganisms. By analyzing known microbial genomic islands and prophages, we developed criteria for systematic identification of putative genomic islands (clusters of genes of probable horizontal origin in a prokaryotic genome) in 63 prokaryotic genomes, and then characterized the distribution of novel genes and other features. All but a few of the genomes examined contained significantly higher proportions of novel genes in their predicted genomic islands compared with the rest of their genome (Paired t test = 4.43E-14 to 1.27E-18, depending on method). Moreover, the reverse observation (i.e., higher proportions of novel genes outside of islands) never reached statistical significance in any organism examined. We show that this higher proportion of novel genes in predicted genomic islands is not due to less accurate gene prediction in genomic island regions, but likely reflects a genuine increase in novel genes in these regions for both bacteria and archaea. This represents the first comprehensive analysis of novel genes in prokaryotic genomic islands and provides clues regarding the origin of novel genes. Our collective results imply that there are different gene pools associated with recently horizontally transmitted genomic regions versus regions that are primarily vertically inherited. Moreover, there are more novel genes within the gene pool associated with genomic islands. Since genomic islands are frequently associated with a particular microbial adaptation, such as antibiotic resistance, pathogen virulence, or metal resistance, this suggests that microbes may have access to a larger “arsenal” of novel genes for adaptation than previously thought

Patiromer to Enable Spironolactone Use in the Treatment of Patients with Resistant Hypertension and Chronic Kidney Disease: Rationale and Design of the AMBER Study

BACKGROUND: While chronic kidney disease (CKD) is common in resistant hypertension (RHTN), prior studies -evaluating mineralocorticoid receptor antagonists excluded patients with reduced kidney function due to risk of hyperkalemia. AMBER (ClinicalTrials.gov identifier NCT03071263) will evaluate if the potassium-binding polymer patiromer used concomitantly with spironolactone in patients with RHTN and CKD prevents hyperkalemia and allows more persistent spironolactone use for hypertension management. METHODS: Randomized, double-blind, placebo-controlled parallel group 12-week study of patiromer and spironolactone versus placebo and spironolactone in patients with uncontrolled RHTN and CKD. RHTN is defined as unattended systolic automated office blood pressure (AOBP) of -135-160 mm Hg during screening despite taking ≥3 antihypertensives, including a diuretic, and an angiotensin-converting enzyme inhibitor or an angiotensin receptor blocker -(unless not tolerated or contraindicated). The CKD inclusion criterion is an estimated glomerular filtration rate (eGFR) of 25 to ≤45 mL/min/1.73 m2. Screening serum potassium must be 4.3-5.1 mEq/L. The primary efficacy endpoint is the between-group difference (spironolactone plus patiromer versus spironolactone plus placebo) in the proportion of patients remaining on spironolactone at Week 12. RESULTS: Baseline characteristics have been analyzed as of March 2018 for 146 (of a targeted 290) patients. Mean (SD) baseline age is 69.3 (10.9) years; 52.1% are male, 99.3% White, and 47.3% have diabetes. Mean (SD) baseline serum potassium is 4.68 (0.25) mEq/L, systolic AOBP is 144.3 (6.8) mm Hg, eGFR is 35.7 (7.7) mL/min/1.73 m2. CONCLUSION: AMBER will define the ability of patiromer to facilitate the use of spironolactone, an effective antihypertensive therapy for patients with RHTN and CKD