Temperature dependence of quantum lifetime in n-InGaAs/GaAs structures with strongly coupled double quantum wells

Longitudinal ρxx(B) and Hall ρxy(B) magnetoresistances are experimentally investigated as a function of in-plane and transverse magnetic fields in n-InGaAs/GaAs nanostructures with strongly-coupled double quantum wells in the temperature range T = 1.8-70 K and magnetic fields B = 0-9.0 T. Experimental data on the temperature dependence of quantum lifetime in diffusive (kBT/τtr ≪ 1) and ballistic (kBT/τtr ≫ 1) regimes are reported. It has been found that in the ballistic regime in the temperature range where kBT/EF < 0.1, the observed quadratic temperature dependence of quantum lifetime is determined by inelastic electron-electron scattering. However, the temperature dependence of quantum lifetime cannot be quantitatively described by the existing theories in the whole temperature range. © 2013 American Institute of Physics

Rational method of generation of combinations for parallel calculations in some combinatorial problems

Целью данной статьи являлась разработка нового способа нумерации сочетаний. Его особенностью является отсутствие в алгоритме циклов и ветвлений, что позволяет эффективно использовать его в многопоточном режиме. Для выполнения поставленной задачи были произведены разработка алгоритма, нахождение оптимального способа вычисления требуемых величин и оптимизация под многопоточные системы. По сравнению с классическими, данный метод показывает заметное увеличение производительности даже не в самых благоприятных условиях. Особенностью полученного алгоритма является независимое выполнение разных потоков вычисления, что очень важно при выполнении программы на процессорах SIMD архитектуры. Таким образом, разработанный способ нумерации имеет очевидные преимущества и может быть использован в задачах, решаемых методами комбинаторной оптимизации.The purpose of this paper is development of a new method of numbering combinations. Its feature is the absence of loops and branches in the algorithm, which allows using it effectively multithreaded. For this purpose the following tasks have been produced: development of an algorithm, finding an optimal method for calculating the required values and optimization for multi-threaded system. Compared to classical ones, proposed method showed a significant performance increase even in adverse conditions. Thus, the developed algorithm of numbering has obvious advantages, and can be used in tasks, solved by methods of combinatorial optimization

Hole-hole interaction in a strained Inx_xGa1−x_{1-x}As two dimensional system

The interaction correction to the conductivity of 2D hole gas in strained GaAs/In$_x$Ga$_{1-x}$As/GaAs quantum well structures was studied. It is shown that the Zeeman splitting, spin relaxation and ballistic contribution should be taking into account for reliable determination of the Fermi-liquid constant $F_0^\sigma$. The proper consideration of these effects allows us to describe both th temperature and magnetic field dependences of the conductivity and find the value of $F_0^\sigma$.Comment: 7 pages, 6 figure

Tunneling effects in tilted magnetic fields in n-InGaAs/GaAs structures with strongly coupled double quantum wells

The effects of tunneling between two parallel two-dimensional electron gases in n-InGaAs/GaAs nanostructures with strongly coupled double quantum wells with a change in the in-plane component of a tilted magnetic field (up to Bnorm of matrix = 9.0 T) in the temperature range T = 1.8-70.0 K are investigated. A nonmonotonic temperature dependence of the inverse quantum lifetime τq -(T) is obtained from analysis of the dependence of the longitudinal resistance on the parallel component of the tilted magnetic field at fixed temperatures, ρxx(Bnorm of matrix, T). The quadratic portion of this dependence is found to be due to the contribution of inelastic electron-electron scattering. The decrease in the inverse quantum lifetime τq -(T) at T &gt; 0.1T F cannot be described within known theories; it seems, it is not related to the processes of electron momentum relaxation. © 2013 Pleiades Publishing, Ltd

Количественная оценка изрезанности рисунка печатного шрифта и ее влияние на скорость чтения

Для оценки пространственных характеристик шрифтовых рисунков предложено использовать изрезанность — масштабно инвариантный показатель, основанный на идеях фрактальной геометрии. Он чувствителен к форме символов шрифта, которая влияет на разборчивость. Проведенный эксперимент продемонстрировал перспективность применения предложенного показателя для ранжирования шрифтов по скорости чтения.The irregularity, the scale invariant index, based on the ideas of fractal geometry, is proposed to use to assess the spatial features of font’s drawings. The indicator suggests sensitivity to the form of characters which affects font legibility. The conducted study showed the promise of applying the offered index for ranking fonts by reading speeds