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41.
A trie structure can immediately determine whether a desired key is in a given key set or not, and can find its longest match easily. Thanks to these attractive properties, a trie structure is frequently used for various fields, such as natural language dictionaries, database systems and compilers. However, the total number of states of a trie becomes large, so space requirements are not good for a huge key set. To resolve this disadvantage a new structure which reduces the total number of states in a traditional trie, called a double-trie, is introduced in this paper. Insertion and deletion operations, as well as key retrieval for this double-trie, are presented. The efficiency of this method is shown by the results of simulations for various key sets. 相似文献
42.
A new internal array structure, called a double-array, implementing a trie structure is presented. The double-array combines the fast access of a matrix form with the compactness of a list form. The algorithms for retrieval, insertion and deletion are introduced through examples. Although insertion is rather slow, it is still practical, and both the deletion and the retrieval time can be improved from the list form. From the comparison with the list for various large sets of keys, it is shown that the size of the double-array can be about 17 per cent smaller than that of the list, and that the retrieval speed of the double-array can be from 3–1 to 5–1 times faster than that of the list. 相似文献
43.
Cellular and dendritic growth: Part I. Experiment 总被引:3,自引:0,他引:3
Yasunori Miyata Toshio Suzuki Jun-Ichi Uno 《Metallurgical and Materials Transactions A》1985,16(10):1799-1805
An Al-4.1 mass pct Cu alloy was unidirectionally solidified under various growth rates. Features, such as tip radius of curvature,
primary arm spacing, and tip concentration were measured as functions of growth rate. Dependence of tip radius on growth rate
was different between cells and dendrites. Measured tip radius and primary arm spacing were maximum at the cellular-dendritic
transition. Tip concentration, however, monotonously decreases with growth rate. Linear relationships between tip radius and
characteristic dimensions of dendrites like core diameter, half length of tip arc, and the first secondary arm spacing are
obtained to determine what affects growth rate, convection, and gravity segregation. Experimental results are compared with
current theoretical models for dendrite growth under controlled solidification. It was determined that the measured tip radius
is larger than that of theoretical predictions at fast growth rate, but the measured tip concentration is in good agreement
with theoretical predictions. 相似文献
44.
S. Saito K. Suto T. Kimura Jun-Ichi Nishizawa 《Photonics Technology Letters, IEEE》2004,16(2):395-397
The characteristic of 80-ps mode-locked (ML) pulse-pumped gain, which results in a decline that changes from a linear gradient to a square-root gradient at introduced pump densities exceeding 10 dB, makes it difficult to develop pulse-pumped gains for high efficiency amplification. To overcome this disadvantage with pumping, we compared an 80-ps ML pulse and 4-ns Q-switched pulse in a straight waveguide. The amplification of the 4-ns pulse was linear and had a maximum gain of 23.3 dB at an introduced pump density of 1.4 W//spl mu/m/sup 2/ in a straight waveguide. The gain was more efficient than with the 80-ps pulse, which was limited by the optical damage threshold of the input antireflective coating (1.6 W//spl mu/m/sup 2/). These high-gain operations should enable semiconductor Raman amplifiers to be used for detecting signals from chemical or biological materials, in addition to infrared light frequency selective amplification with wavelength-division multiplexing in optical communications. 相似文献
45.
Jun-Ichi Matsuda 《Electron Devices, IEEE Transactions on》1994,41(3):391-397
Methods of measuring leakage currents and the capacitance of the storage capacitor in a single DRAM cell have been developed for correlation with the electrode shape of the capacitor. In the circuit used for these measurements, the plate electrode of the storage capacitor is connected to the gate of the MOSFET which amplifies the voltage variations of the storage capacitor during the measurements. Here, only a conventional transistor parameter analyzer and a capacitance meter are required for the measurements. For the capacitance measurement, the linear region characteristics of the MOSFET are used to simplify the analysis. For the leakage current measurement, however, the subthreshold region characteristics of the MOSFET are used to enhance the accuracy of the measurement. The results show that the very low leakage currents (down to below 0.1 fA) and the capacitance (37.5 fF) of the storage capacitor can be measured accurately. Further, the leakage current-voltage characteristics of the storage capacitor are discussed by comparing with those of a large area planar capacitor whose structure is the same as the storage capacitor 相似文献
46.
Yamada Jun-Ichi Temmyo Jiro Yoshikawa Shokichiro Kimura Tatsuya 《Electronics letters》1980,16(2):57-58
The performance of a 1.6 Gbit/s optical receiver employing a s.a.w. filter as a timing tank is reported. The error-rate characteristics in a p.c.m. transmission system using a 1.3 ?m In-GaAsP laser and single-mode fibres were studied. The average received optical power at a 10?9 error rate was ?28 dBm. In a 15 km transmission experiment, the receiving level was degraded by 2 dB owing to fibre dispersion. Timing phase margin of 75 degrees after 12 km transmission was confined with the self-timed receiver. 相似文献
47.
Hyodo F Tsugeki N Azuma J Urabe J Nakanishi M Wada E 《The Science of the total environment》2008,403(1-3):139-147
We measured stable nitrogen (N) and carbon (C) isotope ratios, lignin-derived phenols, and fossil pigments in sediments of known ages to elucidate the historical changes in the ecosystem status of Lake Biwa, Japan, over the last 100 years. Stable N isotope ratios and algal pigments in the sediments increased rapidly from the early 1960s to the 1980s, and then remained relatively constant, indicating that eutrophication occurred in the early 1960s but ceased in the 1980s. Stable C isotope ratios of the sediment increased from the 1960s, but decreased after the 1980s to the present. This decrease in stable C isotope ratios after the 1980s could not be explained by annual changes in either terrestrial input or algal production. However, when the C isotope ratios were corrected for the Suess effect, the shift to more negative isotopic value in atmospheric CO(2) by fossil fuel burning, the isotopic value showed a trend, which is consistent with the other biomarkers and the monitoring data. The trend was also mirrored by the relative abundance of lignin-derived phenols, a unique organic tracer of material that originated from terrestrial plants, which decreased in the early 1960s and recovered to some degree in the 1980s. We detected no notable difference in the composition of lignin phenols, suggesting that the terrestrial plant composition did not change markedly. However, we found that lignin accumulation rate increased around the 1980s. These results suggest that although eutrophication has stabilized since the 1980s, allochthonous organic matter input has changed in Lake Biwa over the past 25 years. 相似文献
48.
Abstract Electron emission into vacuum from a thin plate of ferroelectric lead-zirconatetitanate (PZT) ceramic has been observed under the impression of electric field of pulse consisting of a pair of positive and negative voltages. The emission was observed at pressure lower than about 10?1 Torr. The emitted charge increases with increasing the positive and the absolute negative voltages of the pulse and the collector voltage. The minimum absolute value of the negative pulse for electron emission is 30V when the positive voltage is larger than 150V. The maximum peak current density is 70A/cm2. It is considered from the electrode area and thickness dependences of the charge that electrons are emitted not only from the ceramic surface near the electrode edge but also through the thin metal electrode. The emitted charge per one pulse little depends on pulse frequency when it is less than 2kHz, and so the total current density can be enhanced by increasing the frequency. The emission is observed even at temperatures above Curie temperature. It is considered that the emission is induced by abrupt change of dielectric flux as well as the polarization reversal. Cathodoluminescence from phosphors excited by the emitted electrons has been observed. 相似文献
49.
The discharge characteristics of a Li/LiyCoO2 cell were simulated by numerical calculations. Based on the program proposed by Newman's group, the change in entropy due to lithium-ion insertion into the active materials was introduced into the open-circuit potential (OCP) for more practical applications. The OCP of LiCoO2 (y = 1) at a full-discharge state was 3.82 V, which was determined from the original program. However, it should show a rapid decrease to minus infinity when discharge is complete (y = 1), which is due to the introduced entropy term. In addition, the local use of active materials across the LiyCoO2 electrode was not uniform, whereas the original program showed a constant value throughout the electrode. Based on the present results, the introduction of an entropy term to the OCP of LiyCoO2 works reasonably well for more practical applications. 相似文献
50.
Horiuchi J Ohba I Tada K Kobayashi M Kanno T Kishimoto M 《Journal of Bioscience and Bioengineering》2003,95(4):412-415
An effective method for cell harvesting of the halotolerant microalga, Dunaliella tertiolecta ATCC30929, was investigated. By increasing the pH of the culture broth using NaOH solution, suspended D. terfolecta cells rapidly coagulated and settled within a few minutes, which allowed simple harvesting of the concentrated cells from the culture broth. The pHs for successful coagulation were between 8.6 and 10.5 and more than 90% of cells was recovered from the culture broth. Clarified culture broth could be reused for the successive cultivation of D. tertiolecta simply by supplying fresh medium and neutralizing alkali with HCl without the requirement for an additional inoculum. 相似文献