Vortex phase diagram in 1111-type CaFe0.89Co0.11AsF single crystal

Studying the vortex properties in high-Tc superconductors is crucial for understanding the high temperature superconducting mechanism. However, until now, only few vortex studies have been performed in 1111-type iron-based superconductors due to their smaller-sized single crystals. In this study, we have synthesized the millimeter-sized CaFe0.89Co0.11AsF single crystals by self-flux method. Three dimensional vortex nature was confirmed in the thermally activated flux flow region. Second magnetization peak was observed on the isothermal magnetization curves. Meanwhile, the dominated role of the normal point pinning was also confirmed. Finally, the various phase boundaries of the vortex were determined based on the analysis of the resistivity and magnetization data, and a complete vortex phase diagram of CaFe0.89Co0.11AsF single crystals was established.

VORTEX OPTIMIZATION ALGORITHM FOR SOLVING OPTIMAL REACTIVE POWER DISPATCH PROBLEM

In this paper, a new Vortex Optimization (VO) algorithm is proposed to solve the reactive power problem. The idea is generally focused on a typical Vortex flow in nature and enthused from some dynamics that are occurred in the sense of Vortex nature. In a few words, the algorithm is also a swarm-oriented evolutional problem solution methodology; since it comprises numerous techniques related to removal of feeble swarm members and trying to progress the solution procedure by supporting the solution space through fresh swarm members. In order to evaluate the performance of the proposed Vortex Optimization (VO) algorithm, it has been tested in Standard IEEE 30 bus systems and compared to other standard algorithms. Simulation results reveal about the best performance of the proposed algorithm in reducing the real power loss and static voltage stability margin index has been enhanced.

Effects of heat treatment on the microstructure and metallurgical properties of the explosively bonded 304 stainless steel—CK45 steel

In this research, the effects of heat treatment are studied on the microstructure and mechanical properties of the explosive bonding of 304 stainless steel plates and CK45 carbon steel with a constant explosive load and various standoff distances. The samples are heat treated in a furnace for 2-h and 4-h at 250℃ and 350℃. The results imply that by increasing the standoff distance from 4 to 5 mm, the impact kinetic energy increases and severe plastic deformation occurs in the bonding interface. The metallography results indicate the wave-vortex nature of the interface with the increase of standoff distance. In addition, heat treatment for 2 h at 350℃ leads to an increase in the thicknesses of intermetallic compounds in the interface. Also, the hardness decreases from 271 to 171 Vickers, and from 279 to 195 Vickers with 2 h of heat treatment at 350℃ in samples with standoff distances of 4 and 5 mm, respectively. Furthermore, the strengths of the samples decrease from 449 to 371 MPa, and from 510 to 433 MPa, respectively. Hardness and strength changes occur due to changes in the thickness of the intermetallic area and an increase in grain sizes.

Compact Heat Sink With Combined Structures of Dimples-Protrusions With Pin-Fins or Micro-Channels: Review, Simulation and Experimental Data

This work presents survey and selected results in the design of compact heat sinks for semiconductor industry that use concavities, dimples or protrusions, combined structures of dimples and pin-fins with or without micro-channels, and methods of manufacturing based on “wave” technology. Analysis and observations in this work are devoted to the study of flow structure and jet-vortex nature of heat transfer enhancement mechanisms in a single dimple, in an array of dimples and in dimpled channels at a different Reynolds number, dimple depth and dimple shape. Impulse and heat transfer analogy in channels with dimples and protrusions are also considered. The direct numerical simulation and experimental analysis are performed for channels with combined structure of dimples and pin-fins. The thermal resistance and dependences of Nusselt number on Reynolds number are reported for studied arrangements at which dimples do not act as surface vortex generators.

The Multiple-Vortex Nature of Tropical Cyclogenesis

This study explores the extent to which potential vorticity (PV) generation and superposition were relevant on a variety of scales during the genesis of Tropical Storm Allison. Allison formed close to shore, and the combination of continuous Doppler radar, satellite, aircraft, and surface observations allows for the examination of tropical cyclogenesis in great detail. Preceding Allison’s genesis, PV superposition on the large scale created an environment where decreased vertical shear and increased instability, surface fluxes, and low-level cyclonic vorticity coexisted. This presented a favorable environment for meso-α-scale PV production by widespread convection and led to the formation of surface-based, meso-β-scale vortices [termed convective burst vortices (CBVs)]. The CBVs seemed to form in association with intense bursts of convection and rotated around each other within the meso-α circulation field. One CBV eventually superposed with a mesoscale convective vortex (MCV), resulting in a more concentrated surface vortex with stronger pressure gradients. The unstable, vorticity-rich environment was also favorable for the development of even smaller, meso-γ-scale vortices that formed within the cores of deep convective cells. Several meso-γ-scale convective vortices were present in the immediate vicinity when a CBV developed, and the smaller vortices may have contributed to the formation of the CBV. The convection associated with the meso-γ vortices also fed PV into existing CBVs. Much of the vortex behavior observed in Allison has been documented or simulated in studies of other tropical cyclones. Multiscale vortex formation and interaction may be a common aspect of many tropical cyclogenesis events.