Three-dimensional flow visualization system by holographic interferometry

A holographic system has been developed to visualize a three-dimensional fluid flow. The system consists principally of a thermoplastic film, a monochrome video camera, a microcomputer with image-processing capability and a printer. The system makes it possible to measure a slow flow. Two examples of such, the bimodal mixed-mode convection flows within a Bénard cell, are presented

Structure Evolution of Volcanic Glass by Dynamic Compression

金沢大学大学院自然科学研究科東北大学"Scedule:17-18 March 2003, Vemue: Kanazawa, Japan, Kanazawa Citymonde Hotel, Project Leader : Hayakawa, Kazuichi, Symposium Secretariat: XO kamata, Naoto, Edited by:Kamata, Naoto

Insolation-driven 100,000-year glacial cycles and hysteresis of ice-sheet volume

The growth and reduction of Northern Hemisphere ice sheets over the past million years is dominated by an approximately 100,000-year periodicity and a sawtooth pattern (gradual growth and fast termination). Milankovitch theory proposes that summer insolation at high northern latitudes drives the glacial cycles, and statistical tests have demonstrated that the glacial cycles are indeed linked to eccentricity, obliquity and precession cycles. Yet insolation alone cannot explain the strong 100,000-year cycle, suggesting that internal climatic feedbacks may also be at work. Earlier conceptual models, for example, showed that glacial terminations are associated with the build-up of Northern Hemisphere ‘excess ice’, but the physical mechanisms underpinning the 100,000-year cycle remain unclear. Here we show, using comprehensive climate and ice-sheet models, that insolation and internal feedbacks between the climate, the ice sheets and the lithosphere–asthenosphere system explain the 100,000-year periodicity. The responses of equilibrium states of ice sheets to summer insolation show hysteresis, with the shape and position of the hysteresis loop playing a key part in determining the periodicities of glacial cycles. The hysteresis loop of the North American ice sheet is such that after inception of the ice sheet, its mass balance remains mostly positive through several precession cycles, whose amplitudes decrease towards an eccentricity minimum. The larger the ice sheet grows and extends towards lower latitudes, the smaller is the insolation required to make the mass balance negative. Therefore, once a large ice sheet is established, a moderate increase in insolation is sufficient to trigger a negative mass balance, leading to an almost complete retreat of the ice sheet within several thousand years. This fast retreat is governed mainly by rapid ablation due to the lowered surface elevation resulting from delayed isostatic rebound, which is the lithosphere–asthenosphere response. Carbon dioxide is involved, but is not determinative, in the evolution of the 100,000-year glacial cycles

Phytophthora capsici Leonian 菌の被のう胞子の発芽過程における核現象(農学部門)

本報告はPhytophthora capsiciの被のう胞子, その発芽過程および小遊走子のう形成に至る間の現象, とくに核現象について研究を行なったものである。被のう胞子の発芽は20°∿28℃で良好であり, その発芽管の伸長は24℃が最適である。被のう胞子の発芽に際し, 原形質は発芽管ないし小遊走子のう内へ流動移行するが, 栄養を補う以前には原形質量の増加は認められない。遊走子の核は1つである。しかし被のう胞子が発芽過程に移る際に, 被のう胞子内で核分裂がはじまるものと, 発芽管の頸部で核分裂がおこるものとが認められるが, 発芽管の伸長とともに引続き発芽管内で核分裂が行なわれる。発芽管内の核分裂は32°, 24°, 20℃の順に早く行なわれるが, いずれの温度でも18時間後には平均8核になる。小遊走子のうは比較的高温においてよく形成し, その形成初期から成熟期前にかけて核数は増加し, 約3∿4個程度に達するが, 成熟期に達してのちは核数が減少し, ついに1核になる。この1核になった時期は小遊走子のうの発芽に移る時期とよく一致する。The germination of cystospore and the formation of miniature sporangium of Phytophthora capsici Leonian have been studied with special emphasis on the nuclear phenomena in those processes. The cystospore germinated in the temperature range of 20°∿25℃, but the germ tube elongation was best demonstrated at 24℃. On cystospore germination cytoplasmic contents were translocated to the germ tube and then to the miniature sporangium formed on the tip of the germ tube or its branch. No increment in the cytoplasmic volume was observed if nutrient was deprived of the germination medium. Zoospore and encysted zoospore have one nucleus. The nuclear division was observed to be initiated either in the cystospore or in the constricted part of the germ tube. In either case divisions were continued in the germ tube as it elongated. The time of division cycle seemed to be dependent on temperature. It was shortest at 32℃ followed by 24℃ and 20℃ in the order. The number of nuclei, however, reached to 8 in average after 18 hrs incubation at any temperature tested. Relatively higher temperature seemes to be favorable for the formation of miniature sporangia. Number of nuclei in the miniature sporangia increased to 3 or 4 in the early stage of their formation, but it decreased as the sporangia grew to the maturity, finally becomming to one. Judging from the time sequence, germination of miniature sporangia seemes to be initiated as soon as number of nucleus decreased to one

Study of the effect of mechanical impact parameters on an impact-mode piezoelectric ceramic power generator

This paper presents an analytical and experimental study on the effect of mechanical impact parameters on impact-mode piezoelectric ceramic power generators. The parameters are the velocity and mass. The method of analysis is based on a weight drop experiment. The results show that the peak of the instantaneous output voltage is proportional to the impact velocity, and for the output power, it is in a straight line relationship with the same parameter. For the same velocity of impact, the advantage of using heavy objects is clear because its momentum and the impact force are higher. However, an adjustment in the velocity of impact is found to be more effective for higher instantaneous output power than the mass. This finding is supported by the output power that is generated by a 4-g steel ball with a momentum of 4.34 gm/s, which is almost 300% higher than that of an 8-g steel ball for the same momentum. The frequency responses of a vibration-based impact-mode piezoelectric ceramic power generator also support the same conclusion

The Effect of the Parameters of a Vibration-Based Impact Mode Piezoelectric Power Generator

This study reports the effects of the parameters of a vibration-based impactmode piezoelectric power generator. First, an evaluation of the effects of the impact parameters, the mass, and the impact velocity is presented. It is found that the output voltage of the piezoelectric device in impactmode is directly proportional to the velocity,whereas the output power is equal to a quadratic function of the same variable. For the same impact momentum, the effect of the velocity in generating a higher peak output is dominant compared with the mass. Second, the vibration-based impact mode piezoelectric power generator is discussed. The experimental results show that a wider operating frequency bandwidth of the output power can be achieved with the preloading configuration. However, regardingmagnitude, due to the high velocity of impact, the configurationwith a gap between the tip and the piezoelectric device produces a higher output

Shape Effect of Piezoelectric Energy Harvester on Vibration Power Generation

Vibration energy harvesting is widely recognized as the useful technology for saving energy. The piezoelectric energy harvesting device is one of energy harvester and is used to operate certain types of MEMS devices. Various factors influence the energy regeneration efficiency of the lead zirconate titanate piezoelectric (PZT) devices in converting the mechanical vibration energy to the electrical energy. This paper presents the analytical and experimental evaluation of energy regeneration efficiency of PZT devices through impedance matching method and drop-weight experiments to different shape of PZT devices. The results show that the impedance matching method has increased the energy regeneration efficiency while triangular shape of PZT device produce a stable efficiency in the energy regeneration. Besides that, it becomes clear that the power, energy and subsequently efficiency of the triangular plate are higher than those of the rectangular plate under the condition of the matching impedance and the same PZT area