1,971 research outputs found
Determining the cutting conditions for sculptured surface machining
No full textThis paper deals with a new method for determining cutting conditions for the machining of 3D sculptured surface shapes with a ball endmill. Since the interaction area between workpiece and cutting tool changes during ball endmill machining, the cutting conditions have to be changed accordingly. To determine the spindle speed, the tool-workpiece contact area is obtained from the depth of cut, path interval, and cutter contact (CC) data. The spindle speed is determined so that the tangential cutting speed of the centroid of the tool-workpiece contact area becomes the value suggested in the machining data handbook. The feedrate is determined so that the material removal rate is maximised within the range of the cutting-force constraint. The practical feasibility of the proposed scheme has been verified through experiments performed on a workpiece with sculptured surfaces. The test result shows that the new method can be used to increase the tool life, and improve the production rate. © 1993 Springer-Verlag London Limited
Role of thermal excitation in ultrafast energy transfer in chlorosomes revealed by two-dimensional electronic spectroscopy
No full textChlorosomes are the largest light harvesting complexes in nature and consist of many bacteriochlorophyll
pigments forming self-assembled J-aggregates. In this work, we use two-dimensional electronic
spectroscopy (2D-ES) to investigate ultrafast dynamics of excitation energy transfer (EET) in chlorosomes
and their temperature dependence. From time evolution of the measured 2D electronic spectra of
chlorosomes, we directly map out the distribution of the EET rate among the manifold of exciton states in
a 2D energy space. In particular, it is found that the EET rate varies gradually depending on the energies of
energy-donor and energy-acceptor states. In addition, from comparative 2D-ES measurements at 77 K and
room temperature, we show that the EET rate exhibits subtle dependence on both the exciton energy and
temperature, demonstrating the effect of thermal excitation on the EET rate. This observation suggests that
active thermal excitation at room temperature prevents the excitation trapping at low-energy states and
thus promotes efficient exciton diffusion in chlorosomes at ambient temperature.1441sciescopu
Ultrafast energy transfer in chlorosome probed by femtosecond pump-probe polarization anisotropy
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Fast two-step deposition of perovskite via mediator extraction treatment for large-area, high-performance perovskite solar cells
No full textAs the efficiency of perovskite solar cells (PSCs) reached more than 22%, the large-area fabrication of PSCs became another issue receiving growing attention. For large-area PSCs, more reproducibility is required to precisely control the crystallization behavior of perovskites. A two-step process has been preferred to apply large-area coatings of perovskite because of its better reproducibility, but the process has suffered from slow and incomplete conversion of PbI2 to perovskite. In this paper, we propose a fast, simple, two-step methodmediator extraction treatment (MET)for the preparation of a high-quality perovskite film. In MET, a pre-deposited PbI2-DMSO complex film is converted into a peculiar PbI2 film with a porous morphology and unusual crystallographic orientation via the removal of DMSO. PbI2 could be completely converted into MAPbI(3) by a fast reaction with MAI molecules. We demonstrate that this MET process in MAPbI(3)-based PSCs can achieve 18.8% of the maximum power conversion efficiency (PCE) using spin-coating, and 18.3% of the maximum PCE using slot-die coating with a uniform distribution in a 10 x10 cm(2) substrate at a laboratory scale. Moreover, over 18% of PCE could be achieved in only 100 s, and with room-temperature processing
A Fully-Integrated 0.9W/mm<sup>2</sup> 79.1%-Efficiency 200MHz Multi-Phase Buck Converter with Flying-Capacitor-Based Inter-Inductor Current Balancing Technique
No full textThis paper presents a fully-integrated (highly-integrated) 0.9W/mm2 (1.01W/mm2) 79.1% (81.4%)-efficiency 2-phase buck converter using on-chip (bond-wire) inductors and a 88.1%-efficiency 4-phase one with external components. They feature in-channel and inter-channel current self-balancing enabled by using flying-capacitor that is mainly aimed to lower the switching voltage. Also, the charge-recycling gate driver is proposed. The chips fabricated in a 55nm CMOS achieve a 45V/s DVS rate and a transient slew rate of 9A/s
A Fully Integrated Multi-Phase Voltage Regulator With Flying-Capacitor-Based Inter-Inductor Current Self-Balancing Scheme and Charge-Recycling Gate Driver
No full textThis article presents a fully integrated voltage regulator (FIVR) featuring a high power density, fast dynamic voltage scaling (DVS), and self-balanced inductor currents. The proposed two-phase 2L1C buck converter topology can 2 reduce the number of power switches and flying capacitors (CF) compared to the conventional two-phase three-level (2P3L) converters while inheriting the benefit of a lower switching voltage. The single-CF-based self-balancing of the inductor currents with no extra overhead is a key contribution to this work. For the high scalability of the 2L1C topology, the inter-channel balancing (ICB) scheme is also presented. Moreover, the proposed charge-recycling gate driver is capable of reducing the switching power loss. The proposed two-phase FIVR chip with on-chip spiral inductors of 2 nH was fabricated in a 55-nm CMOS process. The chip operating at 200 MHz/phase showed a 45-V/ mu s DVS rate and a transient slew rate of 40 mA/ns. The measured power density and the peak efficiency were 0.9 W/mm(2) and 79.1%, respectively. The ICB scheme was demonstrated with the four-phase VR chip able to supply a maximum output power of 2 W.
"Spectrum engineering using lattice-amplified Mie-resonators: Full and gradient structural colors
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Deinococcus hibisci sp. nov., isolated from rhizosphere of Hibiscus syriacus L. (mugunghwa flower)
No full textMoya, Gabriela, Yan, Zheng-Fei, Chu, Dong-Hun, Won, KyungHwa, Yang, Jung-Eun, Wang, Qi-Jun, Kook, Moo-Chang, Yi, Tae-Hoo (2018): Deinococcus hibisci sp. nov., isolated from rhizosphere of Hibiscus syriacus L. (mugunghwa flower). International Journal of Systematic and Evolutionary Microbiology 68 (1): 28-34, DOI: 10.1099/ijsem.0.002405, URL: http://dx.doi.org/10.1099/ijsem.0.00240
Female patient before and after TAE.
No full text<p>(A): before TAE the hepatic hemangioma filled almost all of the right liver. Three months after TAE, the hepatic hemangioma was smaller than before TAE (B), and it became even smaller six months later (C).</p
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