Shock tube studies of thermal radiation of diesel-spray combustion under a range of spray conditions

A tailored interface shock tube and an over-tailored interface shock tube were used to measure the thermal energy radiated during diesel-spray combustion of light oil, α-methylnaphthalene and cetane by changing the injection pressure. The ignition delay of methanol and the thermal radiation were also measured. Experiments were performed in a steel shock tube with a 7 m low-pressure section filled with air and a 6 m high-pressure section. Pre-compressed fuel was injected through a throttle nozzle into air behind a reflected shock wave. Monochromatic emissive power and the power emitted across all infrared wavelengths were measured with IR-detectors set along the central axis of the tube. Time-dependent radii where soot particles radiated were also determined, and the results were as follows. For diesel spray combustion with high injection pressures (from 10 to 80 MPa), the thermal radiation energy of light oil per injection increased with injection pressure from 10 to 30 MPa. The energy was about 2% of the heat of combustion of light oil at P _inj = about 30 MPa. At injection pressure above 30 MPa the thermal radiation decreased with increasing injection pressure. This profile agreed well with the combustion duration, the flame length, the maximum amount of soot in the flame, the time-integrated soot volume and the time-integrated flame volume. The ignition delay of light oil was observed to decrease monotonically with increasing fuel injection pressure. For diesel spray combustion of methanol, the thermal radiation including that due to the gas phase was 1% of the combustion heat at maximum, and usually lower than 1%. The thermal radiation due to soot was lower than 0.05% of the combustion heat. The ignition delays were larger (about 50%) than those of light oil. However, these differences were within experimental error.

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An abridged version of this paper was presented at the 18th Int. Symposium on Shock Waves at Sendai, Japan during July 21 to 26, 1991 and at the 19th Int. Symposium on Shock Waves at Marseille, France during July 26 to 30, 1993.     

A six-axis hybrid vibration isolation system using active zero-power control supported by passive weight support mechanism

This paper presents a six-degree-of-freedom hybrid vibration isolation system integrated with an active negative suspension, an active-passive positive suspension and a passive weight support mechanism. The aim of the research consists in maximizing the system and control performances, and minimizing the system development and maintenance costs. The vibration isolation system is, fundamentally, developed by connecting an active negative suspension realized by zero-power control in series with an active-passive positive suspension. The system could effectively isolate ground vibrations in addition to suppress the effect of on-board generated direct disturbances of the six-axis motions, associated with vertical and horizontal directions. The system is further reinforced by introducing a passive weight support mechanism in parallel with the basic system. The modified system with zero-power control allows simplified design of the isolation table without power consumption. It also offers enhanced performance on direct disturbance suppression and large payload supporting capabilities, without degrading transmissibility characteristics. A mathematical model of the system is presented and, therefore, analyzed to demonstrate that zero-compliance to direct disturbance could be generated by the developed system. Experimental demonstrations validate the proposed concept that exhibits high stiffness of the isolation table to static and dynamic direct disturbances, and good transmissibility characteristics against ground vibration. Further improvements of the vibration isolation system and the control system are discussed as well.     

Change in the dispersion states of short-length-cellulose nanofibers upon dilution investigated by a time-domain nuclear magnetic resonance (TD-NMR)

Cellulose - A short-length cellulose nanofiber (CNF) aqueous sol, prepared by a high-pressure homogenizer, showed a rapid longer relaxation time (T2) in the low-field 1H-nuclear magnetic resonance...     

Molecular doping in amorphous selenium

The transport properties of vacuum evaporated selenium doped with small quantities of atoms (Li, Ga, In, Cl, etc.), and compounds (LiCl, GaF₃, In₂O₃, etc.) are examined using time-of-flight technique. When doped with certain compounds (for example, GeO₂), electrons and holes show comlex transport behavior different from the compensation effect due to co-doping of the component atoms (Ge, O). This suggests that these compounds are taken into selenium in the “molecular form”.     

Inhibitors of skin-tumor promotion. VIII. Inhibitory effects of euglobals and their related compounds on Epstein-Barr virus activation. (1)

Twelve euglobals from Eucalyptus globulus and their twenty-six related compounds were examined for their inhibitory effects on Epstein-Barr virus activation by a short-term in vitro assay. The results showed that most of the euglobals having monoterpene structures, and euglobal-III (8) had strong inhibitory activity. Grandinol (18), homograndinols (19 and 20), and compounds 26, 27, 28, and 32 showed stronger inhibitory effects. Based on the results, the structural requirements for the activity of these compounds were discussed.