Reduction in higher order effects on logic functions of asymmetricnonlinear optical fiber couplers by bandwidth limited amplification

Higher order effects such as third-order dispersion, shock effect, and soliton self-frequency shift on all-optical logic gates that use asymmetric nonlinear optical fiber couplers are investigated with the beam propagation method, and it is found that third-order dispersion seriously affects the operations of logic devices. In contrast to the case of nonvanishing third-order dispersion, the radiation is stimulated, and consequently the operations of the logic devices are degraded. In order to diminish the degradation, the bandwidth limited amplification is introduced. The logic functions can be improved by trapping only the soliton components in the finite gain-bandwidth     

Multiband single-layer frequency selective surface designed by combination of genetic algorithm and geometry-refinement technique

This paper proposes an optimization-design method for the frequency selective surface (FSS) based on the genetic algorithm (GA) incorporated with a geometry-refinement technique. The present method takes the connectivity condition of the elements into consideration, thereby resulting in an easy fabrication. As an example, we design the multiband single-layer FSS for transmitting L band (1.5 GHz band) and S band (2.5 GHz band) and also reflecting Ka band (20/30 GHz band). The designed FSS has bandwidths broader than previous FSSs. Finally, the validity of the present method is proved by the agreement between the calculated and the measured transmission responses for the designed FSS.     

Development of simulation software for MAG butt welding

MAG (metal active gas) arc welding is an important and widely used welding process that allows welding to proceed at high efficiency through appropriate selection of operating parameters, such as the welding current, welding speed, shielding gas composition, etc. Experimental determination of optimum operating parameters, however, is costly and time-consuming, although welding process simulations based on mathematical models are expected to be able to solve the problem of time and costs.     

Yielding behavior and its effect on uniform elongation in IF steel with various grain sizes

In the present study, IF steel specimens with different grain sizes ranging from 12 to 0.45 μm were fabricated by accumulative roll-bonding process and subsequent annealing. Tensile tests revealed that by decreasing the mean grain size down to an ultrafine range smaller than approximately 1.5 μm, yielding behavior of the IF steel gradually changed from continuous yielding to discontinuous yielding. An abrupt loss in the uniform elongation occurred, when the average grain size was smaller than about 1 μm. Hall–Petch analysis on the yield stress and uniform elongation implied that the abrupt loss in the uniform elongation in the UFG grain size range corresponded to the appearance of the discontinuous yielding behavior. As it has been found in many UFG materials, discontinuous yielding is believed to be a unique mechanical behavior of UFG materials, and it has significant importance on the uniform elongation of UFG materials.     

Analysis of energy service systems in urban areas and their CO2 mitigations and economic impacts

Three kinds of energy service system were examined as alternative energy systems in urban areas. A comparison of these energy systems was performed by finding Pareto optimum solutions for a multi-objective model. The model had two objective functions: CO₂ emission and cost to consumer. Various energy pricings were provided in the model as variables.     

Manipulation of small particles utilizing electrostatic force

We developed electrostatic system for manipulating small particles with diameters in the range of several micrometers to 100 μm. The electrostatic manipulation probe consists of a monopole pin electrode. When voltage is applied to the electrode, a dielectrophoresis force generated in the nonuniform electrostatic field is applied to the particle near the tip of the electrode. The particle is captured with the application of voltage, and then it is released from the probe by applying a high voltage of the opposite polarity. It is possible to manipulate not only insulative but also weakly conductive particles. A three-dimensional field calculation and a measurement of the adhesion force were conducted to evaluate the force balance for the capture and release of a particle. On the basis of these investigations, we demonstrated the manipulation of actual lunar dust returned by the Apollo 11 lunar surface mission.     

Acid resistance and verocytotoxin productivity of enterohemorrhagic Escherichia coli O157:H7 exposed to microwave

Abstract: We examined the acid resistance and verocytotoxin (VT) productivity of enterohemorrhagic Escherichia coli O157:H7 irradiated by microwave with a domestic microwave oven and a commercial microwave radiator equipped with a thermo‐regulator. When the cell suspension (5 mL) chilled at 0 °C was treated with a domestic microwave oven at weak power (2.45 GHz, 100 W) for 60 s, the living cell number was reduced by 2 orders (final temperature, about 65 °C). The surviving cells showed lower acid resistance and VT productivity than nonirradiated cells. To examine the nonthermal effect of microwave on acid resistance and VT productivity, the cells in Luria‐Bertani medium were intermittently irradiated to keep the culture temperature at 37 °C with the microwave radiator (2.45 GHz, 0.6 W/mL). The intermittent radiation slightly reduced the acid resistance, but clearly suppressed the VT productivity. Microwave oven is probably useful for reducing not only the living cell number but also the acid resistance and VT productivity of EHEC O157:H7.     

Spectral properties of nanoengineered Ag/Au bilayer rods fabricated by electron beam lithography

Ag/Au bimetallic nanoparticles possess the combinatory advantages of Au and Ag nanoparticles and can also be utilized to tune the properties of localized surface plasmon resonance. Ag/Au bilayer nanorods were prepared by electron beam lithography, and their spectral properties were investigated. Compared with Ag monolayer nanorods, Ag/Au bilayer nanorods show broader localized surface plasmon resonance bands, and the longitudinal mode and transverse mode localized surface plasmon bands show blueshift and redshift, respectively. The maximum near-field intensity of the longitudinal mode of the Ag/Au nanorod is less than half that of the Ag/Au nanorod without gold layer. Shape-induced modification of Ag/Au bilayer nanorods on their spectral properties was also discussed.     

Martensite/austenite interfaces in ultrafine grained Fe–Ni–C alloy

In this article, orientation relationships (ORs) at martensite/austenite interface (M/A interface) transformed from coarse-grained and ultrafine-grained austenites were investigated. The results showed that the OR at the M/A interfaces of lenticular martensite transformed from coarse-grained austenite was close to Kurdjumov–Sachs (K–S). The OR of butterfly martensite was close to K–S in the outer side of M/A interface and it deviated to Nishiyama–Wasserman (N–W) at the inner side of M/A interface. In contrast, the OR of lenticular martensite transformed from ultrafine-grained austenite was close to Greninger–Troiano (G–T), and the OR of butterfly martensite was close to K–S at outer side of M/A interface and it deviated to G–T at the inner side of M/A interface. The significantly small size of martensite plate transformed from ultrafine-grained austenite resulted in the different ORs from coarse-grained austenite.