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431.
Takahiko Akiyama Junji Itoh Kohei Fuchibe 《Advanced Synthesis u0026amp; Catalysis》2006,348(9):999-1010
Hydrogen bond catalysis and Brønsted acid catalysis are rapidly growing areas in organocatalysis. A number of chiral acid catalysts has been developed recently. Recent progress in the chiral Brønsted acid catalysis has been reviewed with a focus being placed on thiourea, TADDOL, and phosphoric acids. 1 Introduction 2 Hydrogen Bond Catalysis 2.1 Monofunctional Thiourea Catalysts 2.2 Bifunctional Thiourea Catalysts 2.3 TADDOL Derivatives 2.4 BINOL Derivatives 3 Brønsted Acid Catalysis 3.1 Ammonium Salts 3.2 Phosphoric Acids 4 Conclusion 相似文献
432.
Jian‐Guo Dai Tamon Ueda Yasuhiko Sato Kohei Nagai 《Computer-Aided Civil and Infrastructure Engineering》2012,27(6):406-418
Abstract: Allowing for the tension stiffening effects resulting from the bond between steel reinforcement and surrounding concrete leads to effective deformation analysis of reinforced concrete (RC) members when using a nonlinear finite element analysis modeled on the smeared crack concept. Nowadays, externally bonded fiber reinforced polymer (FRP) composites are widely used for strengthening existing RC structures. However, it remains unclear to what extent the tension stiffening of postcracking concrete is quantitatively influenced by the addition of FRP composites, as a result of the bond between the FRP and the concrete substrate. This article presents a discrete model, which is based on rigid body spring networks (RBSN), for investigating the tension stiffening behavior of concrete in FRP‐strengthened RC tensile members. A two‐parameter fracture energy‐based model was deployed to represent the bond‐slip behavior of the FRP‐to‐concrete interface. The reliability of the RBSN model was verified through comparisons with previous test results. Further parametric analysis indicates that the tension stiffening of concrete is hardly influenced by the addition of FRP composites before the yield of steel reinforcement has occurred although concrete crack patterns and crack widths may be influenced by the bond‐slip behavior of the FRP‐to‐concrete interface. 相似文献
433.
Kaoru Yamamoto Kohei Fujita Izuru Takewaki 《The Structural Design of Tall and Special Buildings》2011,20(6):631-648
The input energy and energy input rate to a base‐isolated (BI) building during an earthquake are considered and formulated in the frequency domain. The frequency‐domain approach for computation of input energy and energy input rate has different remarkable advantages compared with the conventional time‐domain approach. It is demonstrated that the input energy can be of a compact form via the frequency integration of the product between the input component (squared Fourier amplitude spectrum of acceleration) and the structural model component (so‐called energy transfer function). Furthermore, the energy input rate can also be of a similar form via the frequency integration of the product between the instantaneous power spectrum and the energy transfer function. With the help of this compact form, it is shown that the formulation in the frequency domain is essential for deriving arbitrary‐order closed‐form sensitivities of the input energy and energy input rate with respect to uncertain stiffness and damping coefficients in the BI storey. The closed‐form sensitivity expressions provide us with information on the most unfavourable variation of the uncertain parameters that leads to the maximum input energy and input rate. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
434.
Ehab Mahmoud Mohamed Sherief Hashima Kohei Hatano Hani Kasban Mohamed Rihan 《计算机、材料和连续体（英文）》2020,65(3):1987-2007
The communication in the Millimeter-wave (mmWave) band, i.e., 30~300 GHz, is characterized by short-range transmissions and the use of antenna beamforming (BF). Thus, multiple mmWave access points (APs) should be installed to fully cover a target environment with gigabits per second (Gbps) connectivity. However, inter-beam interference prevents maximizing the sum rates of the established concurrent links. In this paper, a reinforcement learning (RL) approach is proposed for enabling mmWave concurrent transmissions by finding out beam directions that maximize the long-term average sum rates of the concurrent links. Specifically, the problem is formulated as a multiplayer multiarmed bandit (MAB), where mmWave APs act as the players aiming to maximize their achievable rewards, i.e., data rates, and the arms to play are the available beam directions. In this setup, a selfish concurrent multiplayer MAB strategy is advocated. Four different MAB algorithms, namely, ϵ-greedy, upper confidence bound (UCB), Thompson sampling (TS), and exponential weight algorithm for exploration and exploitation (EXP3) are examined by employing them in each AP to selfishly enhance its beam selection based only on its previous observations. After a few rounds of interactions, mmWave APs learn how to select concurrent beams that enhance the overall system performance. The proposed MAB based mmWave concurrent BF shows comparable performance to the optimal solution. 相似文献
435.
We investigated the interfacial effects on magnetic properties in Co2Fe(Al,Si)/Ge (CFAS/Ge) and CFAS/MgO/Ge systems to demonstrate the effects of the interface structure on magnetic properties. CFAS and CFAS/MgO were deposited on the i-Ge(111) substrate. In-situ reflection high energy electron diffraction (RHEED) patterns showed epitaxially grown CFAS and MgO on Ge(111). According to the X-ray diffraction (XRD) ϕ-scan of CFAS(220), we determined that the crystallographic orientation relationships were CFAS(111)<–110>// Ge(111)<–110> and CFAS(111)<–110>//MgO(111)<–110>Ge(111)<–110>. The magnetic properties were measured by the vibrating sample magnetometer (VSM) and the saturation magnetization Ms value of CFAS with 2-nm thick MgO reached the value of L21 ordered one. A uniaxial magnetic anisotropy behavior was observed both in CFAS/Ge and CFAS/MgO/Ge structures after annealing. We confirmed the behavior did not only originate from the CFAS/Ge interface but also CFAS/MgO and the ordering structure. 相似文献
436.
Kohei Ohta Nei Kato Glenn Mansfield Yoshiaki Nemoto 《International Journal of Network Management》1996,6(2):108-118
Configuring a network management system involves the delicate art of balancing the requirements of the management system with the available network resources. 相似文献
437.
Kohei Nakamura Kentaro Nakayama Tomoka Ishibashi Noriyoshi Ishikawa Masako Ishikawa Hiroshi Katagiri Toshiko Minamoto Emi Sato Kaori Sanuki Hitomi Yamashita Kouji Iida Razia Sultana Satoru Kyo 《International journal of molecular sciences》2016,17(5)
Ovarian low-grade serous carcinoma is thought to begin as a serous cystadenoma or adenofibroma that progresses in a slow stepwise fashion. Among the low-grade serous carcinomas, there is a high frequency of activating mutations in the KRAS or BRAF genes; however, it remains unclear as to how these mutations contribute to tumor progression. This is the first report to track the histopathological progression of serous adenofibroma to low-grade serous carcinoma. Each stage was individually analyzed by pathological and molecular genetic methods to determine what differences occur between the distinct stages of progression. 相似文献
438.
Mizuho Kondo Kohei Goto Yoshiyuki Dozono Nobuhiro Kawatsuki 《Reactive and Functional Polymers》2013,73(11):1567-1572
The cooperative molecular reorientation in methacrylate copolymer films comprising photoreactive 4-(4-methoxycinnamoyloxy)biphenyl and phenylamide in their side chains was investigated by irradiation with linearly polarized ultraviolet light and subsequent annealing. Both cinnamate and phenylamide side groups were miscible in the copolymer composition, and axis-selective photoreaction of the cinnamate groups was observed. Thermally enhanced cooperative in-plane orientation of both side groups was obtained when the irradiated films were annealed in the liquid-crystalline temperature range of the copolymers. 相似文献
439.
Engineering with Computers - In this study, a new computational approach for determination of the bond strength of fibre reinforced polymer (FRP) strip-to-concrete joints is presented based on... 相似文献
440.
Kohei Nakashima Yuki Nakano Soichi Ishihara Yoshio Murakami Masago Yamamoto 《Journal of Mechanical Science and Technology》2010,24(1):227-230
In two-stroke cycle engines, the piston and piston ring slide over not only the cylinder wall but also the cylinder ports.
This study investigates whether piston rings project and get caught in the cylinder ports. We installed strain gauges, on
the bottom sides of piston rings, over the intake and exhaust ports, and plotted the variation of strain per cycle, while
running the engine. By examining the variation in strain on the bottom of the piston ring, we clarified that our piston ring
indeed became momentarily caught in the cylinder ports. 相似文献