Optical Fractional Derivative Matched Correlator

We suggest a new optical matched correlator which combines the fractional derivative with the conventional correlation for application to space shift-invariant pattern recognition. This new correlator possesses the favorable feature of being able to enhance the discrimination capability and anti-interference to noise ability over that of the conventional matched spatial filter. Varying the fractional order enables one to trade off between the light efficiency and the discrimination ability of the correlator.     

Effects of crosslinker density on the polymer network structure in poly‐N,N‐dimethylacrylamide hydrogels

To investigate the effects of crosslinker density on the properties of hydrogels, compression tests, scanning electron microscopy (SEM), differential scanning calorimetry (DSC), and Raman measurements were performed on poly‐N,N‐dimethylacrylamide hydrogels. The results of the compression tests showed that the Young's modulus increases as the crosslinker density increases. To understand the mechanism of the change in the mechanical properties, the structures of the polymer networks and water and the molecular vibrations were analyzed using SEM, DSC, and Raman methods. From the SEM images, it was found that the porosity estimated from the mesh size and cell density increases with increasing crosslinker density. In addition, the DSC and Raman results show that the thickness of the bound water increases as the porosity increases, although the density of the polymer chains in the porous wall remains nearly constant. The increase in the number density of polymer chains can be one of the mechanisms contributing to the increase in the mechanical strength of the hydrogels at lower crosslinker density below 5 mol %, as proposed by previous studies. At higher crosslinker density, however, the number density of polymer chains does not increase with increasing crosslinker density. The present results suggest that the bound water plays an important role in strengthening the hydrogel. The water structure may be one of the dominant factors governing the chemical and physical properties of hydrogels. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2013 , 51, 1017–1027     

Synthesis of 8-bromo-5,12-tetracenequinone and 2-bromotetracene derivatives

A series of bromotetracenequinones 1 and bromotetracenes 2 were prepared from 4-bromophthalic anhydride. The parent tetracenequinone 1a and tetracene 2a were sparingly soluble in organic solvents. In contrast, dipropyl-substituted tetracenequinone 1b and tetracene 2b were a little more soluble. Preparation of dihexyl-substituted tetracene 2c proved to be difficult. Sonogashira coupling of 1b with trimethylsilylacetylene afforded the corresponding product.     

Co-doped Y2O3:Tb3+/Tm3+ multicolor emitting phosphors for thermometry

In this study, the new temperature-dependent phosphor, Y2O3:Tb3+/Tm3+, was investigated for high-temperature thermometry. The photoluminescence intensity at 456?nm emitted from Tm3+ was strong at temperatures higher than 1100?K, whereas the peak intensities emitted from Tb3+ decreased due to the thermal quenching effect. Thus, the intensity ratio between those emissions showed an appropriate variation for thermometry over a wide temperature range. In addition, the phosphors showed a distinct change of visible emission colors from green to blue with increasing temperature. These findings suggest the applicability of these phosphors in visual thermo-sensors.     

Enantioselective Synthesis of [9]‐ and [11]Helicene‐like Molecules: Double Intramolecular [2+2+2] Cycloaddition

The enantioselective synthesis of completely ortho‐fused [9]‐ and [11]helicene‐like molecules has been achieved through a rhodium‐mediated, intramolecular, double [2+2+2] cycloaddition of phenol‐ or 2‐naphthol‐linked hexaynes. Crystal structures and photophysical properties of these [9]‐ and [11]helicene‐like molecules have also been disclosed.     

A novel silver catalyst prepared by using superheated-steam as a heating medium for ethylene oxide production

A high-performance catalyst for the production of ethylene oxide by vapor phase oxidation of ethylene was developed and commercialized. High performance was achieved by the usage of a high surface area carrier with controlled pore distribution and surface acid-base properties, by the adoption of mixed amines to dissolve heat-decomposable silver salt, by the addition of effective additives, and by the introduction of a uniquely developed heat-treatment technology using superheated-steam as the heating medium. The catalyst thus prepared showed high activities because of homogeneously and highly dispersed silver and additive elements within the carrier. As a result, the reaction temperature could be lowered, which led to the improvement of not only the selectivity but also the catalyst life. Heat treatment with superheated-steam proved to have many advantages in producing high-performance catalysts and it is commercially favorable because it needs only a very short processing time.     

Non-Scanning Optical Coherence Tomography Using Off-Axis Interferometry with an Angular-Dispersion Imaging Scheme

We present a non-scanning approach for real-time optical coherence tomography (OCT). Our approach is based on an off-axis interferometer that laterally projects the time-of-flight or depth information of the sample onto an image sensor. To facilitate the use of an off-axis interferometer in OCT, an angular-dispersion imaging method has been developed. Theoretical analysis and experimental results are presented to demonstrate that this method is capable of demodulating the interferogram and thus permits a direct inspection of the depth-resolved image. Depth resolution and detection range of the present method are also studied.     

Optimal checkpointing intervals of three error detection schemes by a double modular redundancy

This paper considers three checkpointing schemes which combine a double modular redundancy and three types of checkpoints: compare-and-store-checkpoint (CSCP), store-checkpoint (SCP), and compare-checkpoint (CCP). An execution time of a task is divided equally into n intervals, and at the end of each interval, a CSCP is always placed. Further, each CSCP interval is also divided equally into m intervals, and at the end of each interval, either CCP or SCP is placed except the last one. Introducing the overheads of comparison, storage, and retry, the mean execution times to complete a task for three schemes are obtained, using the theory of probability. Optimal checkpointing intervals, which minimize the mean times, are analytically derived, and are numerically computed. Three schemes are compared as numerical examples and the best checkpointing scheme is chosen.