Large scale optimization of transonic axial compressor rotor blades

[First Paragraphs] In the present work the Multipoint Approximation Method (MAM) by Toropov et al. (1993) has been applied to the shape optimization of an existing transonic compressor rotor (NASA rotor 37) as a benchmark case. Simulations were performed using the Rolls-Royce plc. PADRAM-HYDRA system (Shahpar and Lapworth 2003, Lapworth and Shahpar 2004) that includes the parameterization of the blade shape, meshing, CFD analysis, postprocessing, and objective/constraints evaluation. The parameterization approach adopted in this system is very flexible but can result in a large scale optimization problem. For this pilot study, a relatively coarse mesh has been used including around 470,000 nodes. The parameterization was done using 5 engineering blade parameters like axial movement of sections along the engine axis in mm (XCEN), circumferential movements of sections in degrees (DELT), solid body rotation of sections in degrees (SKEW), and leading/trailing edge recambering (LEM0/TEMO) in degrees. The design variables were specified using 6 control points at 0 % (hub), 20%, 40%, 60%, 80%, and 100% (tip) along the span. Thus the total number of independent design variables N was 30. B-spline interpolation was used through the control points to generate smooth design perturbations in the radial direction

Magnetic field induced transition in a wide parabolic well superimposed with superlattice

We study a $Al_{x}Ga_{x-1}As$ parabolic quantum wells (PQW) with $GaAs/Al_{x}Ga_{x-1}As$ square superlattice. The magnetotransport in PQW with intentionally disordered short-period superlattice reveals a surprising transition from electrons distribution over whole parabolic well to independent-layer states with unequal density. The transition occurs in the perpendicular magnetic field at Landau filling factor $\nu\approx3$ and is signaled by the appearance of the strong and developing fractional quantum Hall (FQH) states and by the enhanced slope of the Hall resistance. We attribute the transition to the possible electron localization in the x-y plane inside the lateral wells, and formation of the FQH states in the central well of the superlattice, driven by electron-electron interaction.Comment: 5 pages, 4 figure

Automation grade increasing of mine drainage equipment when powered pumps from the soft starter

У статті розглядається доцільність застосування пристроїв плавного пуску асинхронних електродвигунів для систем шахтного водовідливу. Запропоновано алгоритм запуску нерегульованого насоса з використанням аналогового сигналу по струму статора для формування сигналу компенсації швидкості регульованого електродвигуна. Здійснено моделювання та зроблений порівняльний аналіз системи шахтного водовідливу зі стандартним алгоритмом пуску і при використанні сигналу компенсації по струму з подальшою обробкою сигналу в перетворювачі частоти в SoftPLC.In artich feasibility of soft starters for asynchronous motors mine drainage systems is considered. Starting algorithm for unregulated pump using an analog signal by the stator current signal, generated for speed compensation of regulated motor, is proposed. Implemented modeling and comparative analysis of mine drainage systems with a standard starting algorithm and with using of compensation signal by current with the subsequent processing of the signal in the frequency converter with the SoftPLC.В статье рассматривается целесообразность применения устройств плавного пуска асинхронных электродвигателей для систем шахтного водоотлива. Предложен алгоритм запуска нерегулируемого насоса с использованием аналогового сигнала по току статора для формирования сигнала компенсации скорости регулируемого электродвигателя. Осуществлено моделирование, произведен сравнительный анализ системы шахтного водоотлива со стандартным алгоритмом пуска и при использовании сигнала компенсации по току с последующей обработкой сигнала в преобразователе частоты в SoftPLC

Improved molecular descriptors based on the optimization of correlation weights of local graph invariants

We report the calculation of boiling points for several alkyl alcohols through the use of improved molecular descriptors based on the optimization of correlation weights of local invariants of graphs. As local invariants we have used the presence of different chemical elements (i.e. C, H, and O) and the existence of different vertex degree values (i.e. 1, 2, 3 and 4). The inherent flexibility of the chosen molecular descriptor seems to be rather suitable to obtain satisfactory enough predictions of the property under study. Comparison with other similar approximation reveals a very good behavior of the present method. The use of higher order polynomials do not seem to be necessary to improve results regarding the simple linear fitting equations. Some possible future extensions are pointed out in order to achieve a more definitive conclusion about this approximation

Transient reconfigurable subangstrom-precise photonic circuits at the optical fiber surface

Transient fully reconfigurable photonic circuits can be introduced at the optical fiber surface with subangstrom precision. A building block of these circuits - a 0.7Å-precise nano-bottle resonator - is experimentally created by local heating, translated, and annihilated