100 Mb/s optical-repeater experiment employing graded-index fibres

An optical-repeater error-rate experiment is described in which graded-index fibres up to 8 km long are used as a transmission medium. It is shown that 100 Mb/s modulation can be achieved with sufficiently high quality that the received signal can be regenerated for a given bit rate up to the 8 km fibre tested.     

Consecutive reaction kinetics involving a layered structure of the granule in UASB reactors

A consecutive-reaction kinetic model for the sucrose-fed upflow anaerobic sludge bed (UASB) reactor that accounts for a layered structure of the granule and the mass fraction of methanogens (f) is proposed. When the UASB reactor was maintained at the volumetric loading rates (VLR) of 7.9-13.8 kg chemical oxygen demand (COD)/m(3) d, the accumulated volatile fatty acids (VFAs) increased with increasing VLR, whereas the experimental f decreased with increasing VLR. This was primarily because methanogenesis was the rate-limiting step and the sucrose-fed granule was a layered structure. The calculated residual concentrations of sucrose and the intermediates VFAs using the layered-structure model are less deviated from the experimental measurements than those using the homogeneous-structure model. The calculated effectiveness factors for sucrose uptake and intermediates VFAs uptake (eta(1); eta(2)) ranged from 0.18 to 0.35 and 0.65 to 0.96, respectively, indicating that the overall substrate (sucrose or intermediates VFAs) removal in the UASB reactor was diffusion-controlled, especially at the VLRs of 7.9-10.6. kg COD/m(3) d. This finding was also confirmed by the simulated concentration profiles of sucrose and VFAs in the UASB-granule. From the simulation results, the effect of internal mass transfer resistance on overall substrate (sucrose) removal should not be neglected, especially for a granule size of greater than 2.0 mm.     

More than 1000 channel optical frequency chain generation fromsingle supercontinuum source with 12.5 GHz channel spacing

More than 1000 optical frequency channels are generated with 12.5 GHz spacing from a single supercontinuum source. 600-700 channels for the wavelength range 1512-1580 nm are confirmed to offer SNRs and Q factors sufficient for multi-span 2.5 Gbit/s DWDM transmission     

Fabrication of high-aspect-ratio amorphous perfluorinated polymer structure for total internal reflection fluorescence microscopy

A method to fabricate microstructures that are ideal for optical applications was developed. This method enabled structures with a high aspect ratio to be fabricated from an amorphous perfluorinated polymer, CYTOP, which has an identical refractive index to that of water. Using the method, a microwell array device was developed for the purpose of high-throughput protein quantification. Evaluation of the optical properties of the array using total internal reflection fluorescence (TIRF) microscopy demonstrated that the device did not interfere with TIRF imaging at the bottom of each microwell. This method can expand the possible applications of biophotonic devices as well as TIRF imaging.     

Vision‐Based Hierarchical Recognition for Dismantling Robot Applied to Interior Renewal of Buildings

Abstract: New robotic systems are going to play an essential role in the future dismantling service for renewing office interiors in buildings. In dismantling tasks, robots are expected to be able to find and remove very small parts such as screws and bolts. Such recognition of small parts is difficult for robots. The article describes a vision‐based hierarchical recognition applied to dismantling tasks where large structures are detected at first, thus small parts attached to these structures are detected easier. Regarding the items in the ceiling side, after the dismantling task of the ceiling panels, it is necessary to remove carefully the screws that once held these panels to the light gauge steel (LGS), with the purpose of reusing it. With the pose detection of the large structure (LGS) and considering a robot arm with a stereo camera on its tip, a trajectory near that structure can be computed to detect the small parts, in this case the screws. The large structure is detected by using a process of line detection in 2D and its 3D pose is measured with the stereo camera. During the motion along the structure, the screws are detected by applying a multi‐template matching process to every captured image. Followed by, the Support Vector Machine (SVM), which recognizes those screw candidates with high true positive rate and low false positive one. These rates are improved with a temporal multi‐image integration for tracking the screw candidates. In the experiment, 10 actual screws distributed in 1.1 m along a linear segment on the LGS are successfully recognized with a few false positives and with a final computed 3D position of 2 mm in average. Feasibility of methodology is evaluated by experimentation under different lighting conditions in a realistic environment. Experimental results show that the method works well to be applied in an actual dismantling site.     

Fabrication of Pd–DNA and Pd–CNT hybrid nanostructures for hydrogen sensors

This review reports fabrication methods for ordered metallic nanostructures such as nanowires and nanoparticles based on deoxyribonucleic acid (DNA) templates. The phosphate groups in DNA are negatively charged; consequently, the DNA conformation may mineralize metals, e.g., palladium (Pd) at a relatively high metal concentration. We successfully form unique spherically shaped moss-like hybrid Pd nanoparticles using the small compacted globular state of DNA by controlling the reductive reaction. Pd can absorb hydrogen to become PdH_x, and hydrogen storage increases the electrical resistance and volume of Pd materials. Hence, the use of this material is attracting growing interest as a reliable, cheap, ultracompact, and safe hydrogen sensor. Pd–DNA hybrid nanoparticles can be used as highly sensitive hydrogen sensors, which exhibit a switch response that depends on the volume expansion in a cyclic atmosphere exchange. This paper also shows the fabrications of Pd–carbon nanotube (CNT) hybrid nanostructures.     

Improvement of carbon monoxide analysis in fish meat

Carbon monoxide (CO) treatment of fish meat of tuna, yellowtail, tilapia etc. is not allowed in Japan, since it can maintain the red color for a longer period than the microbiological shelf life of fish meat. The official method for quantification of CO has a problem, in that a part of the CO is lost during the preparation of the fish sample. To solve this problem, we modified the official method in this study. We also applied this modified method to survey the contents of CO in tuna, yellowtail, young yellowtail, and tilapia. As a result, the modified method was found to be more suitable for CO quantification than the official method. An inter-laboratory study by 4 laboratories confirmed that the CO content of many samples of tilapia exceeded the regulation value, apparently due to the higher recovery of CO, compared to the official method. Therefore, it was suggested that the regulation value in the case of tilapia should be changed if this method is introduced as an official method.     

A new approach to cutting state monitoring in end-mill machining

A new cutting state monitoring approach is proposed for the real-time predicting of the machining trouble and the surface quality of the machined products. In this approach, the relationships among the mechanical model of cutting process and its corresponding time series model, the surface roughness of the machined workpiece are evaluated through theoretical analysis and experimental investigation. It is therefore revealed that there is the linear relationships among the AR parameter a₁, the stiffness k₃ of cutting model and surface roughness P_z, and consequently the cutting process state can be estimated by only monitoring time series parameter a₁ of vibration signal measured during machining operation. In particular, it was found that the variation in the surface roughness of P_z=3–5 μm can be fully monitored.