Теоретический метод управления расходом перекачиваемой среды по положению запирающих элементов трубопроводной арматуры

Any object located in the pipeline, including the flow meter, leads to a drop in pressure in the pipeline and the need to increase the power of the pumps. Therefore, it seems promising to reduce energy consumption for pumping fluid in the pipeline by reducing the number of flow meters installed after shut-off and control valves and to predict the flow rate of the pumped medium by the position of the locking element in the valve. This will also lead to a reduction in the cost of transporting media by reducing the number of metering devices. In order to solve this complex problem in pipeline transport, the article solves a number of regional problems of hydromechanics based on the finite element method. In order to simplify the acquaintance with these solutions, as well as their practical application by engineers, the article proposes «parametric stationary vortex flow models in such types of shut-off and control valves as a ball valve, butterfly valve, wedge gate valve, angle valve. Without prejudice to generality of the technique, water is considered as an example of a pumped medium. The analysis was performed using FLOTRAN CFD software of ANSYS10 ED program». The article describes in detail the capabilities of both the graphical interface and the command line. Creating models is accompanied by full comments on the actions, which allows any user to master these models. All stages of building models are considered in detail: construction of a solid-state model, selection of elements, appointment of properties of the pumped media, appointment of boundary conditions, as well as solving the problem and viewing the results. «It has been established that the flow rate of the medium is affected both by the geometry of the considered types of shut-off and control valves», and the position of the locking element. The technique can be applied to any designs of pipe fittings associated with calculation of movement of a viscous fluid.Любой объект, расположенный в трубопроводе, в том числе расходомер, приводит к падению давления в трубопроводе и необходимости повышения мощности насосов. Поэтому представляется перспективным снизить энергозатраты на перекачку среды в трубопроводе за счёт уменьшения количества расходомеров, устанавливаемых после запорно-регулирующей арматуры, и прогнозировать расход перекачиваемой среды по положению запирающего элемента в арматуре. Это приведёт также к уменьшению затрат на транспортировку сред за счёт уменьшения количества приборов учёта. В статье с целью решения данной комплексной проблемы на трубопроводном транспорте на основе метода конечных элементов решается ряд краевых задач гидромеханики. С целью упрощения знакомства с данными решениями, а также их применения на практике инженерами, в статье предложены «параметрические модели вихревого стационарного течения в таких видах запорно-регулирующей арматуры, как шаровой кран, дисковый затвор, клиновая задвижка, угловой клапан. Без ущерба общности методики, в качестве примера перекачиваемой среды рассматривается вода. Анализ выполнен средствами FLOTRAN CFD программы ANSYS10 ED». В статье детально описываются возможности как графического интерфейса, так и командной строки. Создание моделей сопровождается полными комментариями о действиях, что позволяет любому пользователю освоить данные модели. Подробно рассмотрены все этапы построения моделей: построение твёрдотельной модели, выбор элементов, назначение свойств перекачиваемых сред, назначение краевых условий, а также решение задачи и просмотр результатов. «Установлено, что на расход среды оказывает влияние, как геометрия рассмотренных видов запорно-регулирующей арматуры, так» и положение запирающего элемента. Методика может быть применена для любых конструкций трубопроводной арматуры, связанных с расчётом движения вязкой жидкости

PEN: a low energy test of lepton universality

Allowed charged $\pi$ meson decays are characterized by simple dynamics, few available decay channels, mainly into leptons, and extremely well controlled radiative and loop corrections. In that sense, pion decays represent a veritable triumph of the standard model (SM) of elementary particles and interactions. This relative theoretical simplicity makes charged pion decays a sensitive means for testing the underlying symmetries and the universality of weak fermion couplings, as well as for studying pion structure and chiral dynamics. Even after considerable recent improvements, experimental precision is lagging far behind that of the theoretical description for pion decays. We review the current state of experimental study of the pion electronic decay $\pi^+ \to e^+\nu_e(\gamma)$, or $\pi_{e2(\gamma)}$, where the $(\gamma)$ indicates inclusion and explicit treatment of radiative decay events. We briefly review the limits on non-SM processes arising from the present level of experimental precision in $\pi_{e2(\gamma)}$ decays. Focusing on the PEN experiment at the Paul Scherrer Institute (PSI), Switzerland, we examine the prospects for further improvement in the near term.Comment: 11 pages, 5 figures; paper presented at the XIII International Conference on Heavy Quarks and Leptons, 22-27 May 2016, Blacksburg, Virginia, US

PEN experiment: a precise measurement of the pi+ -> e+ nu decay branching fraction

A new measurement of $B_{\pi e2}$, the $\pi^+ \to e^+\nu(\gamma)$ decay branching ratio, is currently under way at the Paul Scherrer Institute. The present experimental result on $B_{\pi e2}$ constitutes the most accurate test of lepton universality available. The accuracy, however, still lags behind the theoretical precision by over an order of magnitude. Because of the large helicity suppression of the $\pi_{e2}$ decay, its branching ratio is susceptible to significant contributions from new physics, making this decay a particularly suitable subject of study.Comment: 4 pages, 3 figures, talk given at the Tenth Conference on the Intersections of Particle and Nuclear Physics (CIPANP 2009), La Jolla/San Diego, CA, 26-31 May 2009; to appear in Proceedings to be published by the American Institute of Physic

Effective anisotropy of thin nanomagnets: beyond the surface anisotropy approach

We study the effective anisotropy induced in thin nanomagnets by the nonlocal demagnetization field (dipole-dipole interaction). Assuming a magnetization independent of the thickness coordinate, we reduce the energy to an inhomogeneneous onsite anisotropy. Vortex solutions exist and are ground states for this model. We illustrate our approach for a disk and a square geometry. In particular, we obtain good agreement between spin-lattice simulations with this effective anisotropy and micromagnetic simulations.Comment: ReVTeX, 14 pages, 6 figure