Study on Characteristics of Various RF Transmission Line Structures on PES Substrate for Application to Flexible MMIC

In this work, the coplanar waveguide is fabricated on a PES (poly[ether sulfone]) substrate for application to a flexible monolithic microwave integrated circuit, and its RF characteristics were thoroughly investigated. The quality factor of the coplanar waveguide on PES is 40.3 at a resonance frequency of 46.7 GHz. A fishbone‐type transmission line (FTTL) structure is also fabricated on the PES substrate, and its RF characteristics are investigated. The wavelength of the FTTL on PES is 5.11 mm at 20 GHz, which is 55% of the conventional coplanar waveguide on PES. Using the FTTL, an impedance transformer is fabricated on PES. The size of the impedance transformer is 0.318 mm × 0.318 mm, which is 69.2% of the size of the transformer fabricated by the conventional coplanar waveguide on PES. The impedance transformer showed return loss values better than –12.9 dB from 5 GHz to 50 GHz and an insertion loss better than –1.13 dB in the same frequency range.     

InGaAsP microdisk lasers on AlxOy

InGaAsP microdisk lasers are fabricated on Al_xO_y by wafer fusion. Room-temperature continuous-wave operation with threshold pump power of 1.13 mW has been achieved from a 2.2-μm diameter microdisk laser. The lasing wavelength with incident pump power redshifts at a rate of 0.28 nm/mW which shows the improved thermal characteristics due to the high thermal conductivity of Al_xO _y bottom layer     

Memory-efficient real-time map building using octree of planes and points

This paper presents an octree-based map building algorithm for mobile home-service robots. The robot is equipped with a time-of-flight camera, which produces point clouds of the environment surfaces. Given the successive input of point clouds, a 3D map is incrementally computed in real time. The map is accurate and memory-efficient because the octree nodes containing points on a plane are merged and represented simply by an index to the plane. The real-time performance is achieved largely due to the parallel processing capability of the many-core Graphics Processing Unit used for plane extraction.     

A fault analysis of DC electric arc furnaces with SVC harmonic filters in a mini-mill plant

This paper proposes the most feasible solution to overcome the failure of the 2nd harmonic filter in the static VAR compensator (SVC) which operates with the DC electric arc furnace (EAF) at Gwangyang Steel Mill in Korea. In order to investigate the causes of this failure, various measurements were carried out on the DC EAF and the main transformer at the PCC (point of common connection). It was concluded that the two causes for the failure are; the inrush current in the main transformer, and the parallel resonance between the system impedance and the harmonic filter. Three solutions to suppress the transformer inrush current and another three solutions to avoid the parallel resonance are suggested. The feasibility of these solutions was verified through the computer simulation with PSCAD/EMTDC. The most feasible solution to avoid further failures of the 2nd harmonic filter was selected, based on the estimated result for the six optional solutions in the point of performance and cost.     

Effect of Ta addition on magnetic properties of (Fe45Pt55)1−x-Tax thin films

It was studied that FePt-Ta thin films prepared on MgO (1 0 0) buffer-layer by DC/RF magnetron co-sputtering have shown better magnetic properties and micro structural improvement. The Ta-doped FePt-Ta films indicate somewhat differences in micro structural ordering and the aspect of grain growth after annealing. With respect to magnetic property, the sample having 30% increased coercivity was obtained after a heat treatment at 700 °C. In particular the addition of Ta (5.5%) enhances the L1₀ ordering of FePt at relatively high temperature (above 500 °C).     

Spontaneous Formation of Liquid Crystals in Ultralarge Graphene Oxide Dispersions

A novel process is developed to synthesize graphene oxide sheets with an ultralarge size based on a solution‐phase method involving pre‐exfoliation of graphite flakes. Spontaneous formation of lyotropic nematic liquid crystals is identified upon the addition of the ultralarge graphene oxide sheets in water above a critical concentration of about 0.1 wt%. It is the lowest filler content ever reported for the formation of liquid crystals from any colloid, arising mainly from the ultrahigh aspect ratio of the graphene oxide sheets of over 30 000. It is proposed that the self‐assembled brick‐like graphene oxide nanostructure can be applied in many areas, such as energy‐storage devices and nanocomposites with a high degree of orientation.     

Effects of contact electrode size on the characteristics of polycrystalline-Si p-i-n solar cells

The effects of contact electrode size on the photo-voltaic characteristics of polycrystalline-Si p-i-n solar cells have been studied,with respect to a unit-cell pitch size of 1μm width.For the non-transparent Al contact electrode with a contact width of 0.05-0.2μm,the short-circuit current is obviously reduced with increasing contact width,due to a larger area of optical reflection by the electrode.On the other hand,even when using a transparent ITO(indium-tin-oxide) electrode,a larger width of contact e...     

A wedge crack in an anisotropic material under antiplane shear

A crack emanating from the apex of an infinite wedge in an anisotropic material under antiplane shear is investigated. An isotropic wedge crack subjected to concentrated forces is first solved by using the conformal mapping technique. The solution of an anisotropic wedge crack is obtained from that of the transformed isotropic wedge crack based on a linear transformation method. Expressions for the stress intensity factor for the anisotropic wedge crack with both concentrated and distributed loads are derived. The stress intensity factors are numerically calculated for generally orthotropic wedge cracks with various crack and wedge angles as well as anisotropic parameters.     

On quasi-static crushing of thin-walled steel structures in cold temperature: Experimental and numerical studies

The aim of the study reported herein was to investigate the effects of low temperatures on the crushing characteristics of steel plated structures. The motivation of this study is for the analysis of ship collisions in Arctic waters. A series of tensile coupon tests were performed to examine their material behaviour at low temperatures, and then quasi-static axial crushing tests were carried out on thin-walled square tubes. The test tubes were made of ASTM A500-type carbon steel, and both the tensile coupon tests of the material and the crushing tests of the tubes were performed in a liquid nitrogen cooled chamber. To reflect the conditions of the Arctic environment more realistically, the tensile coupon tests of the material were also carried out in a dry-ice cooled chamber. LS-DYNA nonlinear finite element method simulations applying a practical approach of modelling techniques were performed to investigate the structural crashworthiness of the thin-walled steel tubes numerically. The tests in the liquid nitrogen cooled chamber showed that the fracture strain of the material was not affected (reduced) by temperatures as low as −80 °C, although fracture strain was significantly reduced below −100 °C. The fracture strain results obtained in the dry-ice cooled chamber, however, show this strain to be affected (reduced) by low temperatures even between 0 °C and −80 °C, which is equivalent to the Arctic environment. It was also observed that fracture occurs in thin-walled tubes under crushing loads at low temperatures. The LS-DYNA computations also detected the fracture behaviour of test tubes in cold temperatures in a relevant way.     

接触面陷阱密度对a-InSnZnO薄膜晶体管器件电气性能的影响研究

We reported the influence of interface trap density（Nt） on the electrical properties of amorphous InSnZnO based thin-film transistors,which were fabricated at different direct-current（DC） magnetron sputtering powers.The device with the smallest N_t of 5.68×10¹¹ cm^-2 and low resistivity of 1.21×10^-3Ω·cm exhibited a turn-on voltage(V_ON) of-3.60 V,a sub-threshold swing（S.S） of 0.16 V/dec and an on-off ratio(I_ON/I_OFF) of⁸ x 108.With increasing N_t,the V_ON,S.S and I_ON/I_OFF were suppressed to-9.40 V,0.24 V/dec and 2.59×10⁸,respectively.The V_TH shift under negative gate bias stress has also been estimated to investigate the electrical stability of the devices.The result showed that the reduction in N_t contributes to an improvement in the electrical properties and stability.