Topological Anderson Insulator

Disorder plays an important role in two dimensions, and is responsible for striking phenomena such as metal insulator transition and the integral and fractional quantum Hall effects. In this paper, we investigate the role of disorder in the context of the recently discovered topological insulator, which possesses a pair of helical edge states with opposing spins moving in opposite directions and exhibits the phenomenon of quantum spin Hall effect. We predict an unexpected and nontrivial quantum phase termed "topological Anderson insulator," which is obtained by introducing impurities in a two-dimensional metal; here disorder not only causes metal insulator transition, as anticipated, but is fundamentally responsible for creating extended edge states. We determine the phase diagram of the topological Anderson insulator and outline its experimental consequences.Comment: 4 pages, 4 figure

A Mathematical Theory of the Topological Vertex

We have developed a mathematical theory of the topological vertex--a theory that was original proposed by M. Aganagic, A. Klemm, M. Marino, and C. Vafa in hep-th/0305132 on effectively computing Gromov-Witten invariants of smooth toric Calabi-Yau threefolds derived from duality between open string theory of smooth Calabi-Yau threefolds and Chern-Simons theory on three manifolds.Comment: 66 pages, 10 figures; notation simplified, references adde

Power Amplification and Coherent Combination Techniques for Terahertz Quantum Cascade Lasers

Power amplification and coherent combination are important ways to improve the output power and beam quality of single‐mode terahertz quantum cascade lasers (THz QCLs). Up to date, the tapered waveguide is the most convenient way to amplify the power of THz QCLs. The self‐focusing effect in tapered THz QCLs induces non‐monotonic behaviours of the peak power and far‐field beam divergence, which lead to the existence of optimal structural parameters. The surface and lateral grating techniques have also been employed in tapered THz QCLs to further improve the spectral purity. For coherent combinations, the progress of facet‐emitting phase‐locked arrays of THz QCLs is still limited due to both the lack of the understanding of dynamics of coupled QCLs and the difficulties in designing high‐performance coupled waveguides. We will briefly review the developments of coherent arrays of THz QCLs and present a design of monolithic QCL arrays with common coupled cavity to achieve the optical mutual injection, which may provide a new way for coherent combination of THz QCLs

Zacjeljivanje pukotina u metalu pulsnom strujom

Remanufacture engineering is an emerging industry that saves resources as well as protects the environment. However, cracks on remanufactured components can result in serious trouble. Therefore, in order to avoid unnecessary waste of resources and energy, these cracks should be repaired radically in order to ensure the smooth progressing of the remanufacturing process. Consequently, the crack healing technique of metal materials is very important in the field of remanufacturing. In this study, the U-shape vane stainless steel of a centrifugal compressor which had cracks was processed by pulse current using a high pulse current discharge device, and the influence of the streaming effect and Joule heating effect of pulse current on the crack healing of metal materials was studied, aiming to provide references for the better application of this technology in the remanufacturing field in the future. This work is licensed under a Creative Commons Attribution 4.0 International License.Obnavljanje uređaja i postrojenja pomaže u smanjenju troškova i očuvanju okoliša, ali ozbiljne probleme mogu uzrokovati pukotine na obnovljenim komponentama. Da bi se izbjeglo nepotrebno trošenje energije i sredstava, pukotine se moraju potpuno sanirati. Radi unaprjeđenja tehnike reparacije u ovoj je studiji kompresorska lopatica s pukotinama, izrađena od nehrđajućeg čelika, izložena djelovanju visokonaponske pulsne struje te je proučeno obnavljanje materijala pod utjecajem Jouleove topline i efekta strujanja. Ovo djelo je dano na korištenje pod licencom Creative Commons Imenovanje 4.0 međunarodna

10-Ethyl-10H-phenothia­zine-3-carbaldehyde

In the title mol­ecule, C15H13NOS, the two benzene rings of the tricyclic fused-ring system are inclined at 21.1 (1)°. In the crystal, weak C—H⋯O hydrogen bonds link the mol­ecules into chains along [001]. The crystal packing also exhibits π–π inter­actions with a distance of 3.801 (5) Å between the centroids of the benzene rings of neighbouring mol­ecules