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81.
A study of size and charge-dependent separation of small particles in liquid using a traveling-field-type electric curtain device is made. The principle of the separation is to make use of the spatial harmonic components of the rotating traveling field produced by such a device, the first harmonic propagating in one direction, which plays a dominant role in the region distant from the electrodes, and the second harmonic propagating in the opposite direction, which becomes dominant near the electrodes. Small particles brought into this field undergo circular motion and, as a result of field nonuniformity, are repelled from the electrodes and drift in the direction of the dominant harmonics. The lighter or more charged particles are strongly repelled from the electrodes and swept by the first harmonic, while the heavier or less charged particles can approach the electrodes and are transported by the second harmonic in the opposite direction, thus enabling separation by mass and charge. First a theoretical investigation of this method is made to clarify the operation conditions for the separation, then the experimental observations of particle motion are made and scaling laws of transport velocity with the applied voltage and frequency are confirmed. Finally, an example of a cell separator design using this method is presented.  相似文献   
82.
Position controllers must handle kinetic energy exchanges during acceleration and deceleration of large inertias. Temporary buffer storage in capacitors is expensive. The system that can manage the power exchange with ease is the integrated controlled-current pulsewidth-modulated (PWM) rectifier/controlled-current PWM chopper link. Bidirectional power is accomplished by bidirectional current flow in the dc link for both modulators. The three-phase currents in the rectifier side are near sinusoidal in waveform at unity power factor. The performance of the system as a position controller in an environment of the sliding mode strategy is studied. The sliding mode strategy offers robust characteristics to the controller.  相似文献   
83.
Open microcellular foams of polyethylene terephthalate (PET)/polycarbonate (PC) blends were prepared by controlling their foaming behavior at the interface between these two polymers. Interface modification was a crucial factor in governing the foaming behavior and cell morphology of the blend foams: annealing at 280°C, i.e., conducting the transesterification reaction, generates a PET‐b‐PC copolymer, which lowers the interfacial tension, increases the affinity between PET and PC, and decreases the crystallinity of the PET domains. When CO2 foaming was performed at the interface modified with the copolymer, an interesting fibril‐like structure was formed. The cell density of the PET/PC blend then increased, and its cell size reduced to the microscale while maintaining a high open‐cell ratio. The effect of heat annealing (transesterification reaction) on CO2‐foaming was studied to reveal the relationship among the interface affinity, crystallinity, and degree of fibrillation. The optimal heat‐annealing procedure generated a fibril‐like structure in the PET/PC blend foams with a high cell density (7 × 1011 cm?3), small cell size (less than 2 μm), and 100% open‐cell ratio. POLYM. ENG. SCI., 55:375–385, 2015. © 2014 Society of Plastics Engineers  相似文献   
84.
To determine the behavior of hydrogen in tetralin, the reaction of tetralin with tritiated gaseous hydrogen was studied in a flow reactor at 400–450°C, 2.5–9.8 MPa for various residence times. The amount of hydrogen exchange between tetralin and tritiated hydrogen was estimated from the balance of hydrogen and tritium. Although yields of methylindan and naphthalene, and the hydrogen-exchange ratio (HER) of tetralin increased monotonously with residence time, these values were scarcely influenced by the reaction pressure at every temperature. It was thought that the formation of tetralyl radicals in this system would be the rate-determining step for both the conversions of tetralin into methylindan and naphthalene, and the hydrogen exchange of tetralin. Conversions of tetralin into methylindan and naphthalene, and the hydrogen-exchange reaction using the autoclave were very close to those using the flow reactor.  相似文献   
85.
Highly crystallized BaWO4 films have been prepared on a tungsten substrate in an alkaline solution containing barium ions by an electrochemical method with a constant direct current density of 1 mA/cm2 at room temperature (25°C). The average grain size was about 13 μm, and the thickness about 9 μm after a treatment time of 35 min. The dependence of cell voltage on deposition time was divided into three steps: conduction, anodic oxidation, and breakdown steps. The BaWO4 film formed during the first step. Electrochemical dissolution of metal tungsten occurred with an accompanying positive change of overpotential in the first step. The crystallization of BaWO4 was characterized by three-dimensional nucleation. In the second step, an amorphous tungsten oxide film formed, thereby increasing the potential. An electrical breakdown occurred in the third step, and the breakdown voltage (about 90 V) was practically the same as those of anodic tungsten oxide films.  相似文献   
86.
The decomposition of chlorofluorocarbons (CFCs) in the presence of water was examined over a variety of solid acid catalysts. The TiO2ZrO2 catalyst was found to have the highest activity and longest life among the catalysts examined. The activity of the TiO2ZrO2 catalysts depended upon the content of TiO2. At the contents of TiO2 from 58 to 90 mole%, the TiO2ZrO2 catalysts exhibited high activity, and these catalysts were proven to contain TiZrO4 crystal. From the study of the XRD peak intensity of the TiZrO4 crystal, it was highest on the TZ-58 which contained 58 mole% of TiO2, and decreased with increasing the content of TiO2. Furthermore, the conversion of CFC113 measured at 673 K was highest at TZ-58, and decreased gradually with increasing TiO2 content. Therefore, the TiZrO4 crystal influences the activity of decomposition of CFC113. However, the TiO2ZrO2 catalyst was gradually deactivated during the reaction due to the elimination of titanium atoms. A good relationship was found between the activity on TiO2ZrO2 catalyst and bond energy of CCl in the compounds of chlorofluorocarbons and hydrochlorocarbons, suggesting that the rate controlling step was the cleavage of CCl bond.  相似文献   
87.
Electromagnetic Shielding Properties of Woodceramics Made from Wastepaper   总被引:18,自引:0,他引:18  
Woodceramics are new porous carbon materials, which are made by impregnating woody materials with phenol resin and then thermoformed in a vacuum furnace and these have been shown to have electromagnetic shielding properties. In the recycling of wastepaper, ways of using the wastepaper other than for paper pulp are needed to be developed. In this study, we made Woodceramics from handbill advertisement paper and telephone directory paper, and measured their electromagnetic shielding properties in order to find new uses for wastepaper. The results showed that the Woodceramics made from wastepaper had an electric shielding effectiveness of 30 dB for 100 MHz and 40 to 43 dB for 300 MHz or higher, and had a magnetic shielding effectiveness of 30 dB for 100 MHz and 37 dB for about 400 MHz. An electric equivalent circuit of the pore model in the Woodceramics is introduced. In addition, it is proposed that the excellent electromagnetic shielding effectiveness of the Woodceramics is caused by dielectric loss.  相似文献   
88.
89.
Electrochemical decomposition of CO2 and CO gases using a porous cell of Ru-8 mol% yttria-stabilized zirconia (YSZ) anode/porous YSZ electrolyte/Ni–YSZ cathode system at 400–800 °C was studied by analyzing the flow rate and composition of outlet gas, current density, and phases and elementary distribution of the electrodes and electrolyte. A part of CO2 gas supplied at 50 ml/min was decomposed to solid carbon and O2 gas through the cell at the electric field strengths of 0.9–1.0 V/cm. The outlet gas at a flow rate of 3 ml/min included 61–63% CO2 and 37–39% O2 at 700–800 °C and the outlet gas at a flow rate of 50 ml/min included 73–96% (average 85%) CO2 and 4–27% (average 15%) O2 at 800 °C. On the other hand, the supplied CO gas was also decomposed to solid carbon, O2 and CO2 gases at 800 °C. The fraction of outlet gas at a flow rate of 50 ml/min during the CO decomposition at 800 °C for 5 h was 11–36% CO, 59–81% O2 and 2–9% CO2. The detailed decomposition mechanisms of CO2 and CO gases are discussed. Both Ni metal in the cathode and porous YSZ grains under the DC electric field have the ability to decompose CO gas into solid carbon and O2− ions or O2 gas.  相似文献   
90.
A soluble and stable one-handed helical conjugated polymer without the coexistence of any other chiral moieties was successfully synthesized by asymmetric-induced polymerization of a chiral monomer having two hydroxyl groups followed by desubstitution of the chiral groups in a solid membrane state. The reason for the success was the polymer reaction was carried out in the membrane state. This is an alternative method to obtain such a unique chiral polymer which was obtained only by the helix-sense-selective polymerization (HSSP) we reported before. In addition the efficiency of the chiral induction was higher than that of the HSSP. It is interesting that the “Membrane state” acted like as if a protecting group.  相似文献   
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