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61.
Both theory and studies on models predict that cracks extend stably form flaws in brittle materials subjected to compression. Once cracks have originated and extended, the tensile strength transverse to the cracks should be reduced. Tests on siliconized carbide verify this prediction; however, tests on hot-pressed silicon nitride refute it. Possible morphologies of the inherent flaws are speculated. 相似文献
62.
We have developed a technology for a robot that uses an indoor navigation system based on visual methods to provide the required
autonomy. For robots to run autonomously, it is extremely important that they are able to recognize the surrounding environment
and their current location. Because it was not necessary to use plural external world sensors, we built a navigation system
in our test environment that reduced the burden of information processing mainly by using sight information from a monocular
camera. In addition, we used only natural landmarks such as walls, because we assumed that the environment was a human one.
In this article we discuss and explain two modules: a self-position recognition system and an obstacle recognition system.
In both systems, the recognition is based on image processing of the sight information provided by the robot’s camera. In
addition, in order to provide autonomy for the robot, we use an encoder and information from a two-dimensional space map given
beforehand. Here, we explain the navigation system that integrates these two modules. We applied this system to a robot in
an indoor environment and evaluated its performance, and in a discussion of our experimental results we consider the resulting
problems. 相似文献
63.
We consider how permselectivity as a function of the membrane is related to the cell evolution with an abstract proto-cell
model. We construct an autopoietic proto-cell model having primitive auto-catalytic reaction cycle inside. In this model,
several primitive membrane substances are assumed to be produced from the reaction cycle and the membrane is assumed to have
a permeability to specific chemical species. We show that the permselectivity of the membrane induces the diversification
of the cell volume. We discuss how the diversification of the cells is related to the Darwinian evolution.
This work was presented in part and awarded as Young Author Award at the 13th International Symposium on Artificial Life and
Robotics, Oita, Japan, January 31–February 2, 2008 相似文献
64.
Transient stability may be seriously affected when a large number of distributed generators (DG) stop simultaneously during voltage sag. It is necessary to analyze accurately the dynamics of bulk power systems with high DG penetration. In this paper, transient stability is studied by analyzing power‐angle curves of generators while considering load dynamics and model order reduction at lower voltages. Based on the analysis, a decrease in the load internal resistance after voltage sag causes transient instability of generators. The phenomenon is confirmed through simulation using a one‐machine and one‐load model. This paper also suggests that the simulation results might be misled by traditional bulk power system modeling such as using the static load model and ignoring impedance at lower voltages. As for the numerical simulation, a large level of DG stoppage leads to transient step out in a bulk power system, and the stability is greatly improved by DG voltage regulation. © 2007 Wiley Periodicals, Inc. Electr Eng Jpn, 162(2): 20– 29, 2008; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20608 相似文献
65.
New catalytic technologies in Japan 总被引:9,自引:0,他引:9
Recent trends in R&D of catalytic technology in Japan (cleaner and more efficient production, environmental catalysts, and recycling processes) are overviewed and examples of recent achievements are listed. Examples are then described as zeolite-catalyzed organic reactions recently commercialized and expected to be commercialized: hydration of cyclohexene, synthesis of pyridine derivatives and gas-phase Beckmann rearrangement of cyclohexanone oxime. Finally, as an example of environmental catalysts, the NOx storage–reduction type three-way automobile catalyst, is introduced. 相似文献
66.
Yoshihito Nakagawa Yukihiro Akao Kohei Taniguchi Akemi Kamatani Tomomitsu Tahara Toshiaki Kamano Naoko Nakano Naruomi Komura Hirokazu Ikuno Takafumi Ohmori Yasutaka Jodai Masahiro Miyata Mistuo Nagasaka Tomoyuki Shibata Naoki Ohmiya Ichiro Hirata 《International journal of molecular sciences》2015,16(1):1526-1543
Accumulating data indicates that certain microRNAs (miRNAs or miRs) are differently expressed in samples of tumors and paired non-tumorous samples taken from the same patients with colorectal tumors. We examined the expression of onco-related miRNAs in 131 sporadic exophytic adenomas or early cancers and in 52 sporadic flat elevated adenomas or early cancers to clarify the relationship between the expression of the miRNAs and the endoscopic morphological appearance of the colorectal tumors. The expression levels of miR-143, -145, and -34a were significantly reduced in most of the exophytic tumors compared with those in the flat elevated ones. In type 2 cancers, the miRNA expression profile was very similar to that of the exophytic tumors. The expression levels of miR-7 and -21 were significantly up-regulated in some flat elevated adenomas compared with those in exophytic adenomas. In contrast, in most of the miR-143 and -145 down-regulated cases of the adenoma-carcinoma sequence and in some of the de novo types of carcinoma, the up-regulation of oncogenic miR-7 and/or -21 contributed to the triggering mechanism leading to the carcinogenetic process. These findings indicated that the expression of onco-related miRNA was associated with the morphological appearance of colorectal tumors. 相似文献
67.
Itaru Natori Shizue Natori Hiroyuki Sekikawa Tomoyuki Takahashi Kenji Ogino Kousuke Tsuchiya Hisaya Sato 《Polymer》2010,51(6):1501-3438
The effect of polymer chain structure on the optical and electrical properties are reported for poly(4-diphenylaminostyrene) (PDAS), which was prepared by the living anionic polymerization of 4-diphenylaminostyrene (DAS) with the benzyllithium (BzLi)/N,N,N′,N′-tetramethylethylenediamine (TMEDA) system. The optical properties of PDAS are strongly affected by the stereoregularity of the PDAS polymer chain; intramolecular excimer-forming fluorescence was observed from PDAS with a syndiotactic-rich configuration. The highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energy levels of PDAS were approximately −5.4 and −2.0 eV, respectively, regardless of the polymer chain structure. The hole and electron drift mobilities for PDAS were in the order of 10−4 to 10−5 (cm2/V s) and 10−5 (cm2/V s), respectively, with negative slopes. The distance of each triphenylamino (TPA) group in the polymer chain was a major factor influencing the drift mobility of PDAS. The current-voltage (I-V) characteristics of PDAS were controllable according to the polymer chain structure of PDAS. 相似文献
68.
JosA. Castillo Christine Gurard‐Hlaine Mariana Gutirrez Xavier Garrabou Martine Sancelme Melanie Schürmann Tomoyuki Inoue Virgil Hlaine Franck Charmantray Thierry Gefflaut Laurence Hecquet Jesús Joglar Pere Claps GeorgA. Sprenger Marielle Lemaire 《Advanced Synthesis \u0026amp; Catalysis》2010,352(6):1039-1046
A mutant of D ‐fructose‐6‐phosphate aldolase (FSA) of Escherichia coli, FSA A129S, with improved catalytic efficiency towards dihydroxyacetone (DHA), the donor substrate in aldol addition reactions, was explored for synthetic applications. The kcat/KM value for DHA was 17‐fold higher with FSA A129S than that with FSA wild type (FSA wt). On the other hand, for hydroxyacetone as donor substrate FSA A129S was found to be 3.5‐fold less efficient than FSA wt. Furthermore, FSA A129S also accepted glycolaldehyde (GA) as donor substrate with 3.3‐fold lower affinity than FSA wt. This differential selectivity of both FSA wt and FSA A129S for GA makes them complementary biocatalysts allowing a control over donor and acceptor roles, which is particularly useful in carboligation multi‐step cascade synthesis of polyhydroxylated complex compounds. Production of the mutant protein was also improved for its convenient use in synthesis. Several carbohydrates and nitrocyclitols were efficiently prepared, demonstrating the versatile potential of FSA A129S as biocatalyst in organic synthesis. 相似文献
69.
Tetsuya Shishido Tomoyuki Kitano Kentaro Teramura Tsunehiro Tanaka 《Topics in Catalysis》2010,53(7-10):672-677
Nb2O5/Al2O3 catalysts calcined at high temperatures exhibited the Brønsted acid property. A monolayer of niobic acid-like compound, which has distorted octahedral symmetry, was stabilized over 16 wt% Nb2O5/Al2O3 catalyst calcined at 1,173 K. The two-dimensional Nb–O–Nb network of stabilized niobic acid-like compound probably accounts for the generation of Brønsted acid. 相似文献
70.