Estimation of dynamic rotor loads for the rotor systems research aircraft: Methodology development and validation

The Rotor Systems Research Aircraft uses load cells to isolate the rotor/transmission systm from the fuselage. A mathematical model relating applied rotor loads and inertial loads of the rotor/transmission system to the load cell response is required to allow the load cells to be used to estimate rotor loads from flight data. Such a model is derived analytically by applying a force and moment balance to the isolated rotor/transmission system. The model is tested by comparing its estimated values of applied rotor loads with measured values obtained from a ground based shake test. Discrepancies in the comparison are used to isolate sources of unmodeled external loads. Once the structure of the mathematical model has been validated by comparison with experimental data, the parameters must be identified. Since the parameters may vary with flight condition it is desirable to identify the parameters directly from the flight data. A Maximum Likelihood identification algorithm is derived for this purpose and tested using a computer simulation of load cell data. The identification is found to converge within 10 samples. The rapid convergence facilitates tracking of time varying parameters of the load cell model in flight

Non-interferometric Test of Collapse Models in Optomechanical Systems

The test of modifications to quantum mechanics aimed at identifying the fundamental reasons behind the un-observability of quantum mechanical superpositions at the macro-scale is a crucial goal of modern quantum mechanics. Within the context of collapse models, current proposals based on interferometric techniques for their falsification are far from the experimental state-of-the-art. Here we discuss an alternative approach to the testing of quantum collapse models that, by bypassing the need for the preparation of quantum superposition states might help us addressing non-linear stochastic mechanisms such as the one at the basis of the continuous spontaneous localisation model.Comment: 6 pages, accepted for publication in Phys. Rev. Lett.

Reliability and factorial structure of the farsi version of the Arabic scale of death anxiety in an iranian middle-aged sample

The present study aimed to explore the psychometric properties of the Arabic Scale of Death Anxiety (ASDA) in an Iranian middle-aged sample. A sample of 55 volunteer Iranian persons took part in the study. Cronbach's alpha of the ASDA was found to be high (0.91) and Spearman-Brown and Guttman Split-Half coefficients were 0.86. The factor analysis of the ASDA items yielded five factors accounting for 72.49 of the total variance and labeled (F1) fear of death and fear of dead people; (F2) fear of postmortem events and fear of tombs; (F3) fear of lethal disease; (F4) preoccupation with after death, and death fear in sleep; and (F5) fear of deprivation of own ones. The ASDA has a good validity and reliability, and it can be used in clinical, educational, and research settings. © 2016 Mahboubeh Dadfar and Fazel Bahrami

Potassium 2-oxoimidazolidine-1,3-diide: An effective and new catalyst for the grinding synthesis of (1H-indol-3-yl)methyl-2H-indan-1,3-diones

Potassium 2-oxoimidazolidine-1,3-diide (POImD) is easily used as an efficient and recyclable catalyst for the synthesis of 2H-indene-1,3-dione derivatives by a reaction between indoles, 2H-indene-1,3-dione and aldehydes at room temperature. All reactions are performed in humid POImD in high to excellent yield during short reaction time. Further, the catalyst can be reused and recovered for several times without loss of activity.               KEY WORDS: 1,3-Indandione, Indole, POImD, One pot reaction Bull. Chem. Soc. Ethiop. 2018, 32(2), 399-405.DOI: https://dx.doi.org/10.4314/bcse.v32i2.1

Thermal Assessment of Convective Heat Transfer in Air- Cooled PEMFC Stacks: An Experimental Study

AbstractThis study presents an experimental stack-level thermal and hydrodynamic assessment of a model air-cooled PEM fuel cell. To mimic the heat generation inside the MEA, rubber heater films are used. Pressure drop along the stack channels and temperature distribution on the bipolar plate surface are measured for the channel Reynolds number range of 200-500 and the stack input power range of 100-250W. Tests are performed with and without gas diffusion layers (GDL) to investigate the effect of GDL and its surface characteristics on the pressure drop and heat transfer. Our results indicate that, with the existing length of bipolar plates, a major part of plate minichannel is filled with the developing region. This leads to a higher heat transfer rates, thus more uniform stack temperature can be obtained with the penalty of higher fan power. The minimum measured temperature difference is about 10°C and the values become more pronounced when the Reynolds number decreases. The existence of the GDL is observed to have negligible effect on the pressure drop