Experiments on the Dynamic Behavior of a Supercritical Rotor

Introduction Experiments on the Dynamic Behavior of a Supercritical Rotor The increasing demand for higher speeds and lighter structures in turbomachinery encourages the use of rotors that operate in the supercritical speed range. For these rotors, design criteria must be established regarding the damping and balancing requirements that will ensure safe operation, especially at speeds near and at the bending critical speeds in the operating range. In addition to these requirements, there may be limitations related to instabilities. Sufficient external damping is essential in the application of supercritical rotors. The damping suppresses the potentially large deflections at the critical speeds. It may also be required to overcome other dynamic phenomena occurring in supercritical rotors. Among these are subharmonic resonance due to the non-linear character of the damper forces and instabilities due to internal friction, for example, from shrink fits, sleeves, bolted connections, splines, and flexible couplings. The balancing requirements for supercritical rotors also play an important role in the design phase of aircraft turbine engines. In the first place, balancing limits for production rotors must be attainable with available balancing equipment and methods. Additional problems must also be resolved, such as how to ensure the balance condition of rotors with components that have been replaced in the field. In order to gather experience with regard to the dynamic behavior of supercritical rotors, a number of test rotors has been run in a research program. It is the purpose of this paper to present test results for one of these rotors and to explain some of the aforementioned problems in the light of the data. Related Work The tests have been conducted in an available rig as an extension of a program of earlier investigations related to squeeze-film dampers [l-3]. In these investigations design details of dampers were considered, such as oil supply to the damper, end seals to approximate the "long bearing" condition, no end seals, squirrel cage or retainer springs to center the damper journal, etc. Similar efforts have been reported in the literature. Theoretical predictions of the behavior of closed and open ended dampers are given in Test Rotor The objective of the research program is to establish design criteria for supercritical rotors with respect to critical speeds and unbalance response. This is particularly important in the design of power turbine (PT) rotors which, in the compact arrangements of small aircraft turbine engines, are preferably chosen to be co-axial through the gas generator. Consequently, subcritical PT rotors generally present severe constraints on the design of the engine, especially on the bearing span, diameter and speed of the PT rotor, and on the bore and the length between the PT bearings of the gas generator rotor. The use of a supercritical PT rotor provides some relief on these constraints and, therefore, allows improvement in other basic engine design limits, such as cost, weight, and performance. A number of test rotors, at a scale suitable for testing in an available rig after a minimum of modifications, has been manufactured and is in the process of being tested. The present paper concerns one of them, a rotor on two bearings with an overhanging disk and a balancing collar on the shaf

DEVELOPMENT OF RAPD AND SSR MARKERS ASSOCIATED WITH OIL CONTENT IN FIVE PEANUT CULTIVARS

The peanut (Arachis hypogaea L.) is an important oilseed crop in tropical and subtropical regions of the world.Oil content has an important quality trait for peanut. However, the progress in genetic improvement of oil content is slow. Therefore, identification of molecular markers for oil content trait is  a great impact in molecular breeding. Nineteen RAPD and  ten SSR primers  were used to detect markers related to  oil content in peanut. The five peanut cultivars were grown for two seasons (2013, 2014) in   El-Nubaria, Al-Beheira Governorate, and Egypt. The results showed that, Gregory cultivar recorded the highest value of oil content, while Giza5 cultivar exhibited the lowest value of oil content in both seasons.  The results indicated the presence of five positive and nine negative RAPD markers and  two positive and  one negative SSR markers that could be considered as reliable markers for oil content  in peanut

Salvia fruticosa Induces Vasorelaxation in Rat Isolated Thoracic Aorta: Role of the PI3K/Akt/eNOS/NO/cGMP Signaling Pathway

Salvia fruticosa (SF) Mill. is traditionally used for its antihypertensive actions. However, little is known about its pharmacologic and molecular mechanisms of action. Here we determined the effects of an ethanolic extract of SF leaves on rings of isolated thoracic aorta from Sprague-Dawley rats. Our results show that SF extract increased nitric oxide production and relaxed endothelium-intact rings in a dose-dependent (0.3 µg/ml–1 mg/ml) manner, and the maximum arterial relaxation (Rmax) was significantly reduced with endothelium denudation. Pretreatment of endothelium-intact rings with L-NAME (a non-selective inhibitor of nitric oxide synthase, 100 µM), or ODQ (an inhibitor of soluble guanylyl cyclase, 10 µM) significantly diminished SF-mediated vasorelaxation. Furthermore, SF induced Akt phosphorylation as well as increased cGMP levels in rings treated with increasing doses of SF. Prior exposure to PI3K inhibitors, wortmannin (0.1 µM) or LY294002 (10 µM), decreased cGMP accumulation and attenuated the SF-induced vasorelaxation by approximately 50% (Rmax). SF-evoked relaxation was not affected by indomethacin, verapamil, glibenclamide, tetraethylammonium, pyrilamine or atropine. Taken together, our results indicate that SF induces endothelium-dependent vasorelaxation through the PI3K/Akt/eNOS/NO/sGC/cGMP signaling pathway. Our data illustrate the health-orientated benefits of consuming SF which may act as an antihypertensive agent to reduce the burden of cardiovascular complications.Scopu

Highly efficient adsorption of Cd(II) onto carboxylated camelthorn residues : applicability of three-parameter isotherm models, kinetics, and mechanism

A series of malonic acid treated camelthorn (MATC) sorbents were produced via the reaction of camelthorn biomass with malonic acid, and factors affecting the extent of modification were investigated, including malonic acid concentration, dehydration time and temperature. The optimum sorbent, by carboxylic acid content, was subsequently characterised for surface charge behaviour (pHPZC), surface chemical functionalities (FTIR), morphological structure (SEM), and available surface area. The sorbent was subsequently utilised for adsorption of Cd(II) ions from aqueous media, and parameters influencing adsorption at 30 °C, such as sorbent dose, initial solution pH, exposure time, metal concentration, were investigated. Isothermal analyses were performed using eight models, including two and three parameter equations, with appropriateness of fit assessed via non-linear regression analysis. The adsorption data indicated that the Langmuir model gives the most appropriate fit to experimental curves, with the models ordered as Langmuir >Hill > Toth >Sips > Jossens > Khan > Redlich-Peterson >Freundlich. The highest uptake (qmax) of 582.6 mg g-1 was determined at pH 6. The Freundlich constants, KF and n, at 30 °C were found to be 24.94 mg/g and 2.33, respectively. The value of n (2.33), being in the range 0–10, indicates that adsorption of Cd(II) ions onto malonic acid treated camelthorn biomass is favourable. Evaluation of a series of kinetic models, allowed elucidation of the adsorption mechanism, as a pseudo-second order model gave the most appropriate fit, indicating that chemisorption processes are involved. Cd(II) ions adsorption onto MATC is enhanced by a higher level of active surface sites but was show to be independent of surface area. The work presented here indicates that this sorbent offers effective adsorption potential for Cd(II) ions from water, with potential in wastewater processing

Attention deficit hyperactivity symptoms predict problematic mobile phone use

Attention-deficit-hyperactivity disorder (ADHD) is the most commonly diagnosed childhood disorder characterised by inattention, hyperactivity/impulsivity, or both. Some of the key traits of ADHD have previously been linked to addictive and problematic behaviours. The aim of the present study was to examine the relationship between problematic mobile phone use, smartphone addiction risk and ADHD symptoms in an adult population. A sample of 273 healthy adult volunteers completed the Adult ADHD Self-Report Scale (ASRS), the Mobile Phone Problem Usage Scale (MPPUS), and the Smartphone Addiction Scale (SAS). A significant positive correlation was found between the ASRS and both scales. More specifically, inattention symptoms and age predicted smartphone addiction risk and problematic mobile phone use. Our results suggest that there is a positive relationship between ADHD traits and problematic mobile phone use. In particular, younger adults with higher level of inattention symptoms could be at higher risk of developing smartphone addiction. The implication of our findings for theoretical frameworks of problematic mobile phone use and clinical practice are discussed

Effects of Expert Testimony and Interrogation Tactics on Perceptions of Confessions

Evidence obtained through the process of interrogation is frequently undermined by what can be perceived as overzealous interrogation tactics. Although the majority of psychologically oriented tactics are legally permissible, they nonetheless contribute to innocent suspects confessing to crimes they did not commit. The present study examined the effect of expert testimony and interrogation tactics on perceptions of a confession. 182 undergraduates read a transcript of a homicide trial that varied based on interrogation tactic: implicit threat of punishment (maximization) or leniency (minimization) and expert witness testimony (presence or absence of expert testimony). Analysis indicated that the type of interrogation tactic used in obtaining the confession affected participants\u27 perceptions of the coerciveness of the interrogation process

Teachers\u27 Use of YouTube in the United Arab Emirates: An Exploratory Study

Teachers around the world are using YouTube movies for different purposes. This mixed-methods study was a preliminary investigation of United Arab Emirates teachers\u27 perceptions about YouTube\u27s advantages in the classroom, current practices, and major challenges faced. Forty-five teachers completed an open-ended questionnaire. Results indicated that perceived advantages included supporting the learning process, increasing interest and efficiency, and enriching content. Moreover, findings revealed that the majority of participants were using videos for presentation purposes in teacher-led classrooms. Connectivity, technical issues, appropriateness of content, and administrative support were perceived as major challenges. © 2013 Copyright Taylor and Francis Group, LLC

Moving Towards Accountability for Reasonableness – A Systematic Exploration of the Features of Legitimate Healthcare Coverage Decision-Making Processes Using Rare Diseases and Regenerative Therapies as a Case Study

Background: The accountability for reasonableness (A4R) framework defines 4 conditions for legitimate healthcare coverage decision processes: Relevance, Publicity, Appeals, and Enforcement. The aim of this study was to reflect on how the diverse features of decision-making processes can be aligned with A4R conditions to guide decision-making towards legitimacy. Rare disease and regenerative therapies (RDRTs) pose special decision-making challenges and offer therefore a useful case study. Methods: Features operationalizing each A4R condition as well as three different approaches to address these features (cost-per-QALY-focused and multicriteria-based) were defined and organized into a matrix. Seven experts explored these features during a panel run under the Chatham House Rule and provided general and RDRT-specific recommendations. Responses were analyzed to identify converging and diverging recommendations. Results: Regarding Relevance, recommendations included supporting deliberation, stakeholder participation and grounding coverage decision criteria in normative and societal objectives. Thirteen of 17 proposed decision criteria were recommended by a majority of panelists. The usefulness of universal cost-effectiveness thresholds to inform allocative efficiency was challenged, particularly in the RDRT context. RDRTs raise specific issues that need to be considered; however, rarity should be viewed in relation to other aspects, such as disease severity and budget impact. Regarding Publicity, panelists recommended transparency about the values underlying a decision and value judgements used in selecting evidence. For Appeals, recommendations included a life-cycle approach with clear provisions for re-evaluations. For Enforcement, external quality reviews of decisions were recommended. Conclusion: Moving coverage decision-making processes towards enhanced legitimacy in general and in the RDRT context involves designing and refining approaches to support participation and deliberation, enhancing transparency, and allowing explicit consideration of multiple decision criteria that reflect normative and societal objectives