Volume 2 Issue 3
Authors: Dequn Kong; Qingsuo Liu; Lianjie Yuan; Zhanji Dong
Abstract: This paper designed a nanostructured, low-temperature bainite in a novel bainitic steel with low alloy content of 2.83 wt% in total. Relationships of microstructural characteristic between adjacent bainite sheaves in a prior austenite grain are multiform. Most of the bainite sheaves are randomly distributed in matrix phase, and some specific sheaves are interestingly observed. Butterfly bainite sheaves with angle of 30° are found, and perpendicular sheaves are also obtained.
Keywords: Microstructural Characterization; Bainite; Austempering; Phase Transformations; Nanostructure
Authors: Muhammad Abdul; Umar F. Zubairy; Farhan Saif
Abstract: One dimensional laser logistic map is derived from semi-classical theory of single mode laser and discussed. Later, we write lasers in a ring cavity, with a system of two maps symmetrically coupled. The theoretical system reveals complicated dynamics. We investigated bifurcation phenomenon and crises behavior for the system.
Keywords: Discrete Maps; Instability Behaviour of Strange Attractor; Bifurcation
Authors: Jun Zhou; Xingyi Zhang; Youhe Zhou
Abstract: Levitation force relaxation phenomenon in a superconducting levitation system composed of the high temperature superconducting materials (HTSs) and permanent magnet (PM) materials (or PM guideway) is not avoidable because of the flux creep, an intrinsic feature of the HTSs. In this paper, the influences of the temperature cycle on levitation force relaxation with time were investigated. Some novel experimental results were found and these results are a benefit to the understanding of the HTSs levitation system.
Keywords: Temperature Cycling; Levitation Force Relaxation with Time; High Temperature Superconducting Levitation System
Authors: S.T. Surzhikov; D. A. Storozhev
Abstract: Numerical simulation model of a Direct Current Discharge (DCD) in external magnetic field is used for analysis of behavior of normal DCD at the initial time instants after switching-on of transversal magnetic field. Numerical simulation results are presented for two-dimensional glow discharge at pressure 5 Torr, Emf of power supply of 2 kVolt, and magnetic field induction of B = 0.05 T. The model is based on the diffusion-drift theory of gas discharge consisting of continuity and momentum conservation equations for electron and ion fluids, as well as the Poisson equation for the self-consistent electric field. Feature of our approach is to calculate electron transport coefficients for diffusion-drift model by solving the electron Boltzmann equation. It is shown that the switching-on of transversal magnetic field gives rise to the DCD plasma oscillations. The plasma oscillations are observed also in moving DCD in perpendicular direction to applied electric and magnetic field.
Keywords: Glow Discharge in a Magnetic Field; Electron Kinetic in a Magnetic Field; Diffusion-drift Model of Glow Discharge in a Magnetic Field
Authors: Dhouha Maatar; Regis Fournier; Zied Lachiri; Amine Naitali
Abstract: The aim of this study is to define the effects of influence of the gender, age, height, weight, direction, visual and proprioceptive entries on the mean center of pressure (COP) positions. For that we examined 25 healthy subjects aged between 19-42 years during the quiet stance under static conditions: keeping outspread foot and opened eyes (FO_EO), tighten foot and opened eyes (FT_EO), outspread foot and closed eyes (FO_EC), tightened foot and closed eyes (FT_EC). Experimental results show that since the majority of subjects are right-handled the mean COP position (MCOPP) is on the right sight. They also show that the increase of height moves the COP on the right and forward. The decrease of age and weight moves the COP on the right and forward. It is also displayed that males COP is situated more in the right sight than females COP. Results also show that with absence of visual information, people lean more on forward and the increase of distance between feet lean the COP on backward and to the right.
Keywords: Center of Pressure Displacement; Age; Gender; Weight; Height; Vision; Proprioception; Direction
Authors: Kunihiko Ishihara; Taisuke Tamehira; Masanori Tsuji; Masashi Ichimiya
Abstract: In heat exchangers such as boilers and gas heaters, tube banks are set in a duct such that water passes through inside the tubes and warm gas outside the tubes. Due to the external flow, the resonance phenomenon called the self-sustained tone occurs at a certain velocity. The self-sustained tone might cause noise problems in the surroundings, cause losses due to plant shutdown, etc. The insertion of baffle plates in the duct is one of a few countermeasures of the self-sustained tone. However, the mechanism of suppression of the self-sustained tone is not understood. Therefore, the use of the baffle plate in the tube bank has unclear points for instance baffle plate length and the insertion conditions. Thus, the purpose of this study is to clarify a new mechanism of suppression of the self-sustained tone by baffle plate insertion and the best insertion conditions for baffle plates in tube banks.
Keywords: Self-Sustained Tone; Baffle Plate; Boiler Tube Bank
Authors: Siti Nor Ain Mohamed Ghazali; Norhudah Seman; Mohamad Kamal A Rahim; Sharul Kamal Abdul Rahim
Abstract: This paper presents the planar design of three-section quadrature hybrid coupler for frequency operation of 2 to 6 GHz. This coupler offers a tight coupling of 3 dB and measured return loss better than 13 dB which occupies the size of 50 mm × 20 mm excluding the 50 Ω SMA ports. The proposed quadrature hybrid design is implementing the microstrip-to-slotline transition with multilayer structure. The configuration of this design consists of two substrates layers and one layer ofa ground plane in the middle of the two substrates. Where, the proposed design is formed by rectangular-shaped microstrip line at the top and bottom with rectangular slot at the common ground plane. CST Microwave Studio software is used for coupler design and optimization. Then, the simulated results are compared to the measured results for verification. The characteristics of electric field for odd and even-mode are presented via cross section analysis of the coupler design.
Keywords: Cross-section Analysis; Coupler; Wideband; Microstrip-slot; Quadrature Hybrid
Authors: Fukushi Kawakami; Susumu Inamoto; Shinichi Terazono; Yasuo Inoue; Takayuki Sano
Abstract: As is often experienced, windnoise behaviour on the microphone seems somehow different from those following hydrodynamics or aeromechanics. Based on the preliminary investigation, prototype windscreen was developed for ultralow-frequency noise from wind-generated power facilities or heat-pomp water heater (EcoCute). The performance was discussed and examined from the concentrated viewpoints: (1) reduction of wind noise, (2) insertion loss and (3) water-proof/dew-condensation prevention capability, all about the outermost layer of the screen, as well as the possibility of extending the wind noise reduction by numerical or physical approach. The result implies items (1)-(3) deeply depend on the shape and material of the screen and, above all, the insertion loss on microphone mounting condition inside the screen as well. The new windscreen exhibits around 30 dB reduction below 1kHz, and insertion loss less than ±2dB in 1 Hz-20 kHz. Furthermore, in six-month observation on (3), water leak or dew condensation inside the screen was not found even under the local downpour of 30.5mm/h recorded in July 2010 at Miyazaki, Japan. Finally, numerical compensation by mounting two microphones inside and outside the windscreen, as well as physical approach of employing additional independent wind barrier, both indicated the possibility of additional 10-15dB (45 dB or more in total) reductions each.
Keywords: Infrasound from Wind-generated Power Facility; Waterproof Windscreen; 0-dB Compensation
Authors: Weiguo Yang; Michael A. Fiddy
Abstract: We revisit Pendry’s theory of the “perfect lens” made of a negative index material (NIM) slab and explicitly treat the situation of a lossy NIM. We show that the usual boundary conditions prohibit the situation of ideal lossless NIM where and . We further demonstrate that at the boundary of air and lossy NIM, all input evanescent waves will be refracted into decaying propagating waves inside the NIM, with different spatial frequency components having different propagation directions. Due to the different and non-zero real part of the propagation constant inside the lossy NIM, these high spatial frequency components will not all contribute constructively to the image formed inside the lossy NIM. Accordingly, the information contained in these high spatial frequency components will be lost, making sub-diffraction-limited imaging impossible inside the lossy NIM and in turn for the lossy NIM slab lens’ external image plane.
Keywords: Negative Refraction; Perfect Lens; Electro-Magnetic Boundary Conditions