The present study includes three parts—design and development of rotary liquid nitrogen applicator, investigation of machining performance under cryogenic application by using the developed applicator, and lastly comparison of the performances with dry and flood cutting. The surface milling of hardened EN 24 steel was performed at different speed-feed combinations corresponding to full factorial design plan (48 exp. runs). The effects of cutting speed, feed rate, and cutting conditions were investigated in respect of surface roughness, cutting force, and tool flank wear. The results of this study revealed the supremacy of cryogenic cooling in respect of all investigated quality characteristics. Lack of cooling and lubrication in dry cutting, and inadequate cooling and lubrication of flood cutting resulted in worse performance. On contrary, the double action cooling effect of cryogenic produces a superior performance, when passes through internal channel, firstly—due to an increased heat transfer rate caused by the primary and secondary flow within cutter, and secondly—because of the creation of a swirl flow at the outlet of the channel but within work surface. 相似文献
The reactivity of adsorbed NO (including NO2) and NH3 in the presence of 4.0% oxygen in He was examined over a pitch-based ACF calcined at 800°C. Regeneration at 30°C by 4% O2 in He without NH3 was found to be optimum for the recovery of the initial activity with complete removal of NO within 3 h, with minimum leaks of adsorbed NO and NH3. A higher temperature of 40°C for regeneration increased the liberation of adsorbed NO, and NH3 over ACF was rather slow at a lower temperature of 25°C, slow regeneration being achieved. Oxygen appears necessary to regenerate the ACF through enhancing the reaction of adsorbed NO and NH3 for the initial activity, which was ascribed to the catalytic activity for NO–NH3 and adsorption of both NO and NH3. NH3 in the gas phase appears to inhibit the regeneration reaction of adsorbed species, by using the leaking amount during the regeneration. 相似文献
On 16 April 2016, a Mw 7.0 earthquake occurred in Kumamoto city, Japan. The main shock induced two large landslides, namely the Aso Bridge landslide and the Aso Volcanological Laboratory landslide. Their topographical and geological conditions and motion features were investigated by using an unmanned aerial vehicle (UAV) and portable dynamic cone penetration tests (PPTs). The Aso Bridge landslide lies between elevations of 385 m and 725 m, with a total estimated volume of about 1,980,000 m3. The main body is composed of cohesive soil with lapilli and block. The Aso Volcanological Laboratory landslide lies on a slope between 483 m to 582 m, and the total volume is about 81,000 m3, with an average thickness of 4.5 m. The main body is composed of Kusasenrigahama volcanic pumice tephra beds. The material compositions and deposits of both landslides have low cohesion and easily induced shear failure for the two landslides. The sliding distance of the Aso Bridge landslide was long, the sliding direction almost unchanged from the scarp to the toe, and the sliding speed was rapid. The sliding distance of the Aso Volcanological Laboratory landslide, however, was short, the sliding direction changed from the N-direction at the scarp to the NW-direction at the toe, and the sliding speed was slow.
The electrochemical properties of 2,5-dimercapto-1,3,4-thiadiazole (DMcT)—polyaniline (PAn) composite films containing Pd nanoparticles (average diameter: 28 nm) were investigated. Compared to DMcT–PAn composite film, the DMcT–PAn composite film containing Pd nanoparticles showed enhanced redox current and discharge capacity. The enhanced activity is attributed to the nanosize dispersion of the Pd catalyst particles within the DMcT–PAn matrix. UV-Vis spectroscopy and X-ray photoelectron spectroscopy (XPS) results confirmed the interactions between DMcT and Pd nanoparticles. We have obtained the positive effect of Pd nanoparticles addition on the redox activity of the DMcT–PAn composite. 相似文献
We propose an image cross-connector using an organic photorefractive polymer. With this device, it is possible to perform a reconfigurable connection between multiple input–output image ports by setting the incident angle of individual control beams to minute levels. The use of a polymer can reduce the thickness of the index grating to be induced inside the medium, which can also reduce the distortion of the output image and bring about high precise image connection without an additional optical system. We conduct an experiment with a hole-transport polymer PATPD to verify the operations of an image cross-connector, in which different images from a vertical array of input images would be connected separately to two output ports by two control beams that were injected at different angles. 相似文献
Many experimental studies related to the flow-induced acoustic resonance closed side branches have been reported. However, few studies have reported on the effects of air/steam flow and steam wetness dependence on fluctuating pressure amplitude. Therefore, we investigated the effect of air/steam flow and steam wetness dependence on fluctuating pressure amplitude by conducting a high temperature and high pressure tests at the Hitachi Utility Steam Test Leading Facility (HUSTLE). The test section consisted of a main pipe and a side branch. The side branch was mounted on the long straight main pipe. Fluctuating pressures at the end face of the side branches were measured. The following two results were obtained; the first is that the air/steam flow had little effect on the fluctuating pressure amplitude normalized by dynamic pressure and frequency normalized by the resonance frequency; the second is that under the acoustic resonance (St = 0.41) and non-resonance (St = 0.55) conditions, fluctuating pressure and frequency changed little with steam wetness. The steam wetness during the boiling water reactor operation was less than 0.1%; thus, there was no effect of steam wetness on the acoustic pressure amplitude and the frequency under this operating condition. 相似文献
Si-based inorganic electronics have long dominated the semiconductor industry. However, in recent years conjugated polymers have attracted increasing attention because such systems are flexible and offer the potential for low-cost, large-area production via roll-to-roll processing. The state-of-the-art organic conjugated molecular crystals can exhibit charge carrier mobilities (μ) that nearly match or even exceed that of amorphous silicon (1-10 cm(2) V(-1) s(-1)). The mean free path of the charge carriers estimated from these mobilities corresponds to the typical intersite (intermolecular) hopping distances in conjugated organic materials, which strongly suggests that the conduction model for the electronic band structure only applies to μ > 1 cm(2) V(-1) s(-1) for the translational motion of the charge carriers. However, to analyze the transport mechanism in organic electronics, researchers conventionally use a disorder formalism, where μ is usually less than 1 cm(2) V(-1) s(-1) and dominated by impurities, disorders, or defects that disturb the long-range translational motion. In this Account, we discuss the relationship between the alternating-current and direct-current mobilities of charge carriers, using time-resolved microwave conductivity (TRMC) and other techniques including field-effect transistor, time-of-flight, and space-charge limited current. TRMC measures the nanometer-scale mobility of charge carriers under an oscillating microwave electric field with no contact between the semiconductors and the metals. This separation allows us to evaluate the intrinsic charge carrier mobility with minimal trapping effects. We review a wide variety of organic electronics in terms of their charge carrier mobilities, and we describe recent studies of macromolecules, molecular crystals, and supramolecular architecture. For example, a rigid poly(phenylene-co-ethynylene) included in permethylated cyclodextrin shows a high intramolecular hole mobility of 0.5 cm(2) V(-1) s(-1), based on a combination of flash-photolysis TRMC and transient absorption spectroscopy (TAS) measurements. Single-crystal rubrene showed an ambipolarity with anisotropic charge carrier transport along each crystal axis on the nanometer scale. Finally, we describe the charge carrier mobility of a self-assembled nanotube consisting of a large π-plane of hexabenzocoronene (HBC) partially appended with an electron acceptor. The local (intratubular) charge carrier mobility reached 3 cm(2) V(-1) s(-1) for the nanotubes that possessed well-ordered π-stacking, but it dropped to 0.7 cm(2) V(-1) s(-1) in regions that contained greater amounts of the electron acceptor because those molecules reduced the structural integrity of π-stacked HBC arrays. Interestingly, the long-range (intertubular) charge carrier mobility was on the order of 10(-4) cm(2) V(-1) s(-1) and monotonically decreased when the acceptor content was increased. These results suggest the importance of investigating charge carrier mobilities by frequency-dependent charge carrier motion for the development of more efficient organic electronic devices. 相似文献
A coupled thermal–electrical analysis of carbon fiber reinforced polymer composites (CFRP) exposed to simulated lightning current was conducted in order to elucidate the damage behavior caused by a lightning strike with the numerical results being compared to experimental results. Based on the experimental results and a preliminary analysis, the specific mechanism of electrical conduction through the thickness direction of CFRP following thermal decomposition was revealed to be a key parameter for accurate numerical simulation. In particular, assuming the electrical conductivity in the thickness direction to be linear with respect to temperature in the range from the epoxy decomposition temperature to carbon sublimation temperature produced reasonable numerical results. The delamination area and damage depth were estimated from numerical results and thermal decomposition behavior of CFRP with the estimated damage area agreeing qualitatively with the experimental results. Numerical results suggest that Joule heat generation significantly influences lightning strike damage. 相似文献
Properties of single grain boundaries in ZnO:rare-earth varistors were examined by the isothermal capacitance transient spectroscopy (ICTS) method. Micro-electrodes prepared by photolithography were used for measuring the behavior of single junctions in ZnO varistors. From current-voltage measurements, it was found that the non-linear exponents of single junctions varied from 3 to 14. Interface state levels existed at 0.9 eV below the conduction band edge for every junction. On the other hand, the interface state density varied from junction to junction and the non-linearity was shown to increase with increasing interface state density. 相似文献