Fluid transport properties under confined conditions

This paper was presented at the 4th Micro and Nano Flows Conference (MNF2014), which was held at University College, London, UK. The conference was organised by Brunel University and supported by the Italian Union of Thermofluiddynamics, IPEM, the Process Intensification Network, the Institution of Mechanical Engineers, the Heat Transfer Society, HEXAG - the Heat Exchange Action Group, and the Energy Institute, ASME Press, LCN London Centre for Nanotechnology, UCL University College London, UCL Engineering, the International NanoScience Community, www.nanopaprika.eu.The problem of adequate description of transport processes of fluids in confined conditions is solved using methods of nonequilibrium statistical mechanics. The «fluid–channel wall» system is regarded as a two-phase medium, in which each phase has a particular velocity and temperature. The obtained results show that the transfer equations describing transport processes in confined spaces should contain not only the stress tensor and the heat flux vector, but also the interfacial forces responsible for the transfer of momentum and heat due to the interaction with the wall surfaces. The stress tensor and the heat flux vector fluid can be expressed in terms of the effective viscosity and thermal conductivity. However, the constitutive relations contain additive terms that correspond to the fluid–surface interactions. Thus, not only do the fluid transport coefficients in nanochannels differ from the bulk transport coefficients, but also they are not determined only by the parameters of the fluid

Long Wavelength VCSELs and VCSEL-Based Processing of Microwave Signals

We address the challenge of decreasing the size, cost and power consumption for practical applications of next generation microwave photonics systems by using long-wavelength vertical cavity surface emitting lasers. Several demonstrations of new concepts of microwave photonics devices are presented and discussed

Transverse instabilities of multiple vortex chains in superconductor-ferromagnet bilayers

Using scanning tunneling microscopy and Ginzburg-Landau simulations we explore vortex configurations in magnetically coupled NbSe$_2$-Permalloy superconductor-ferromagnet bilayer. The Permalloy film with stripe domain structure induces periodic local magnetic induction in the superconductor creating a series of pinning-antipinning channels for externally added magnetic flux quanta. Such laterally confined Abrikosov vortices form quasi-1D arrays (chains). The transitions between multichain states occur through propagation of kinks at the intermediate fields. At high fields we show that the system becomes non-linear due to a change in both the number of vortices and the confining potential. The longitudinal instabilities of the resulting vortex structures lead to vortices `levitating' in the anti-pinning channels.Comment: accepted in PRB-Rapid

К ВОПРОCУ ОПТИМИЗАЦИИ ПРОЦЕCCОВ ЛЕТНО-ТЕХНИЧЕCКОЙ ЭКCПЛУАТАЦИИ ВОЗДУШНЫХ CУДОВ ПО КРИТЕРИЮ МИНИМАЛЬНОГО РАCХОДА ТОПЛИВА

Potentially new ways to improve civil aircraft fuel efficiency, based on the aircraft maintenance process optimization are considered. The data confirming the advisability of their further in-depth study and implementation in civil aviation airlines activity is given.It is shown that one of the reasons provoking the increase of fuel consumption at the cruising flight stage might be the necessity of the bypass of meteorological areas and of the flight altitude or airspeed change. These events are occasional. At the same time the most advantageous methods aimed at improving fuel efficiency are continuous aircraft climb or descent.One of these research directions is the implementation of continuous descent mode, rational routes of approach to the airfield, climb, choice of optimal flight modes in flights. This program is called “SESAR”. While its realization within the framework of the EC it is planned to reduce fuel consumption by 5 million tons a year due to its economy by 10 % after each flight. The similar program “NextGen” of air traffic optimization is accepted and is realized nowadays in the USA. The purpose of this program is annual improvement of fuel efficiency not less than by 2 % a year.Based on the conducted research the expanded list of recommendations for the realization of aircraft continuous descent system in flight, providing renunciation of horizontal flight areas at idling engines is presented.Рассматриваются новые потенциально возможные пути повышения топливной эффективности гражданских воздушных судов, основанные на оптимизации процесса летно-технической эксплуатации воздушных судов. Приводятся данные, подтверждающие целесообразность их дополнительного углубленного исследования и внедрения в практику работы авиакомпаний гражданской авиации.Показано, что одной из причин, вызывающей увеличение потребления топлива на крейсерском этапе полета, может являться необходимость обхода метеорологических зон и связанное с этим изменение высоты полета или воздушной скорости. Такие события носят эпизодический характер. В то же время наиболее выгодными приемами, направленными на повышение топливной эффективности, являются такие, как выполнение непрерывного набора высоты и снижения воздушных судов.Одним из таких направлений исследования является внедрение в производство полетов режимов непрерывного снижения, рациональных маршрутов подлета к аэропорту посадки, набора высоты, выбор оптимальных профилей полета. Данная программа получила название SESAR. При реализации данной программы в рамках ЕС планируется сократить потребление топлива на 5 миллионов тонн в год за счет его экономии на 10 % по результатам каждого полета. Аналогичная программа NextGen оптимизации процессов воздушного движения принята и в настоящее время реализуется в США. Целью данной программы является ежегодное повышение топливной эффективности не менее чем на 2 % в год.По результатам проведенного исследования представлен расширенный перечень рекомендаций по реализации системы непрерывного снижения воздушных судов при производстве полетов, предусматривающей отказ от горизонтальных участков полета при режиме работы двигателей на малом газе