Sani Y. Harouna-Mayer, Songsheng Tao, ZiZhou Gong
et al.
An approach is described for studying texture in nanostructured materials. The approach implements the real-space texture pair distribution function (PDF), txPDF, laid out by Gong & Billinge {(2018). arXiv:1805.10342 [cond-mat]}. It is demonstrated on a fiber-textured polycrystalline Pt thin film. The approach uses 3D PDF methods to reconstruct the orientation distribution function of the powder crystallites from a set of diffraction patterns, taken at different tilt angles of the substrate with respect to the incident beam, directly from the 3D PDF of the sample. A real-space equivalent of the reciprocal-space pole figure is defined in terms of interatomic vectors in the PDF and computed for various interatomic vectors in the Pt film. Furthermore, it is shown how a valid isotropic PDF may be obtained from a weighted average over the tilt series, including the measurement conditions for the best approximant to the isotropic PDF from a single exposure, which for the case of the fiber-textured film was in a nearly grazing incidence orientation of ∼10°. Finally, an open-source Python software package, FouriGUI, is described that may be used to help in studies of texture from 3D reciprocal-space data, and indeed for Fourier transforming and visualizing 3D PDF data in general.
Hồ Phạm Thành Tâm, Nguyễn Thái Nghe, Nguyễn Chí Ngôn
et al.
Sử dụng năng lượng mặt trời trong nuôi trồng thủy sản là giải pháp phát triển bền vững mà nhà nước đang khuyến khích. Bài báo này nhằm mục tiêu giới thiệu và cung cấp phương pháp triển khai giải thuật dò tìm và bám theo điểm công suất cực đại của tấm pin quang điện (tấm pin năng lượng mặt trời) dựa trên độ điện dẫn của tấm pin (giải thuật Incremental Conductance Maximum Power Point Tracking – Ind. Cond. MPPT). Đây là phần quan trọng để tạo cơ sở triển khai sử dụng năng lượng mặt trời trong các ao nuôi, đặc biệt là giải quyết nhu cầu về năng lượng cho các dàn quạt nước ao tôm (dùng cho cung cấp ôxy và đảo nước trong ao), vì nó giúp khai thác tối đa nguồn năng lượng từ tấm pin năng lượng mặt trời. Dựa trên cơ sở lý thuyết về mô hình của tấm pin quang điện, giải thuật Incremental Conductance được triển khai trong cấu hình mạch chuyển đổi điện áp DC-DC kiểu boost xen kẽ được điều khiển bởi bộ điều khiển kỹ thuật số khả trình (vi điều khiển STM32F1). Kết quả triển khai cho thấy điện áp tại điểm công suất cực đại của hệ pin được duy trì ổn định, công suất trích xuất được điều khiển bám theo công suất khả dụng tối đa của hệ các tấm pin, hệ thống với giải thuật Ind...
In the present work we reply to the Comment by Catalan and Scott (cond-mat/0607500) on two of our papers. This Comment has been rejected from publication in Physical Review Letters and, hence, our Reply is based on the cond-mat version.
This is a reply to W. Zawadzki's paper (arXiv: cond-mat/0701378) on non-exietence of spin transverse force for a relativistic electron. The force was first proposed by the present author that the spin current will experience a transverse force in an electric field as a relativistic quantum mechanical effect, and in semiconductor with Rahsba spin-orbit coupling. Zawadzki's approach is based on an incorrect relation between the velocity and canonical momentum, and his conclusion is not true.
The comment criticisms (cond-mat/0501288) are completely out of line with the context of the commented theory (Phys. Rev. Lett. v.93, 217002 (2004)). The comment neglected essential parts of the theory, which actually addressed all relevant experimental observations. I argue that the coexistence of the large Nernst signal and the insulating-like in-plane resistivity in underdoped cuprates rules out the vortex scenario, but agrees remarkably well with our theory.
A recent paper "Emergence of scaling in random networks" (cond-mat/9910332) by Barabasi and Albert proposes a growth mechanism to produce a stationary scale free distribution of the number of edges per node in large networks such as the Web. The Barabasi-Albert model predicts that older vertices acquire new edges at the expense of younger ones, giving a strong correlation between the time a vertex is introduced and the number of edges it has. We present data from the Web showing that there is no such correlation and point to an alternative growth model which produces the correct relationship between the age of a site and the number of links it has.
The Comment of A. Pelissetto and E. Vicari (cond-mat/0610113) on our article (cond-mat/0609285) is based on misunderstandings of this article as well as on unfounded implicit assumptions. We clarify here the controversial points and show that, contrary to what is asserted by these authors, our paper is free of any contradiction and agrees with all well-established theoretical and experimental results. Also, we maintain that our work reveals pathologies in the (treatment of) perturbative approaches performed at fixed dimensions. In particular, we emphasize that the perturbative approaches to frustrated magnets performed either within the minimal substraction scheme without epsilon-expansion or in the massive scheme at zero momentum exhibit spurious fixed points and, thus, do not describe correctly the behaviour of these systems in three dimensions.
We critically discuss the arguments reported in cond-mat/0609285 by B. Delamotte, Yu. Holovatch, D. Ivaneyko, D. Mouhanna, and M. Tissier. We show that their conclusions are not theoretically founded. They are contradicted by theoretical arguments and numerical results. On the contrary, perturbative field theory provides a robust evidence for the existence of chiral fixed points in O(2) X O(N) systems with N>=2. The three-dimensional perturbative results are consistent with theory and with all available experimental and Monte Carlo results. They provide a consistent scenario for the critical behavior of chiral systems.
This document provides detailed descriptions of data acquisition and data analysis in support of the accompanying Article, cond-mat/0610721: Observation of the two-channel Kondo effect. Some of the most intriguing problems in solid state physics arise when the motion of one electron dramatically affects the motion of surrounding electrons. Traditionally, such highly-correlated electron systems have been studied mainly in materials with complex transition metal chemistry. Over the past decade, researchers have learned to confine one or a few electrons within a nanoscale semiconductor "artificial atom", and to understand and control this simple system in exquisite detail. In the accompanying Article, we combine such individually well-understood components to create a novel highly-correlated electron system within a nano-engineered semiconductor structure. We tune the system in situ through a quantum phase transition between two distinct states, one familiar and one subtly new. The boundary between these states is a quantum critical point: the exotic and previously elusive two-channel Kondo state, in which electrons in two reservoirs are entangled through their interaction with a single localized spin.
In a recent preprint ( cond-mat/0601398 ), D. Funfschilling and G. Ahlers describe a new effect, that they interpret as non-Boussinesq, in a convection cell working with ethane, near its critical point. They argue that such an effect could have spoiled the Chavanne {\it et al.} (Phys. Rev. Lett. {\bf 79} 3648, 1997) results, and not the Niemela {\it et al.} (Nature, {\bf 404}, 837, 2000) ones, which would explain the differences between these two experiments. We show that:-i)Restricting the Chavanne's data to situations as far from the critical point than the Niemela's one, the same discrepancy remains.-ii)The helium data of Chavanne show no indication of the effect observed by D. Funfschilling and G. Ahlers.
We review the main result of cond-mat/0503564. The Hamiltonian of the XXZ spin chain and the transfer matrix of the six-vertex model has the $sl_2$ loop algebra symmetry if the $q$ parameter is given by a root of unity, $q_0^{2N}=1$, for an integer $N$. We discuss the dimensions of the degenerate eigenspace generated by a regular Bethe state in some sectors, rigorously as follows: We show that every regular Bethe ansatz eigenvector in the sectors is a highest weight vector and derive the highest weight ${ar d}_k^{pm}$, which leads to evaluation parameters $a_j$. If the evaluation parameters are distinct, we obtain the dimensions of the highest weight representation generated by the regular Bethe state.