324,652 research outputs found
Shear viscosity of strongly coupled Yukawa systems
No full textT. Saigo and S. Hamaguchi, Physics of Plasmas 9, 1210 (2002) https://doi.org/10.1063/1.145970
Multi-Stage Multi-User Detection Assisted Asynchronous Fast-FH/MFSK
No full textA multi-stage Multi-User Detection (MUD) scheme designed for asynchronous fast Frequency-Hopping/Multilevel Frequency-Shift-Keying (fast-FH/MFSK) systems is proposed, in which each signal detection interval is divided into sub-intervals and the MUD is applied to each sub-interval. In our scheme the MUD exploits the explicit knowledge of the hopping addresses assigned to users. The received signal level is attenuated by a constant scaling factor, when it is deemed to be overwhelmed by multi-user interference. For the sake of preventing erroneous detection events, when communicating over frequency-selective fading channels, the scheme advocated also invokes a space diversity technique. In the investigated scenario the achievable Bit Error Rate (BER) of the proposed scheme was reduced by as much as an order of magnitude in comparison to that of a conventional MUD scheme, when transmitting over an AWGN channel. For transmission over a channel exhibiting uncorrelated frequency-domain fading, selection diversity was used for the sake of achieving a reduced BER
Hamaguchi Osachi and the London Naval Treaty of 1930
No full textA series of political arguments during negotiation and ratification process of the London Naval Treaty of 1930 was one of the most serious domestic political situations in modern Japan within the Cabinet, the Foreign Ministry, the Navy, the political parties such as Minseito and Seiyukai, the Privy Council, the Kizoku-in, the Army and civilian right wingers. The London treaty fight deeply affected the fate of Japan. This study examines the policy argument over the treaty, focusing on Prime Minister Hamaguchi who was a main player to press for the treaty. It has been pointed out that Hamaguchi was moved by budgetary concerns but those who were against ratification of the treaty like Admiral Kato Kanji, were opposed him from military point of view. My interpretation, however, is that there are other significant factors: Hamaguchi's and Kato's argument over how Japanese policy toward the United States and China should be, or the future of Japan should be as a member of international community. Hamaguchi and his opponents' ideas were so different, and that was one of the reasons for their serious conflict. After all the political argument within Japan, it can be said Japan's new state system operated by political parties including the Navy, the Army, and Privy Council was eventually working under the Hamaguchi Cabinet. At the same time, ratification of the London Naval Treaty of 1930 made it possible for Japan to become one of the leading countries in international society, along with the United States and Britain
Wave dispersion relations in Yukawa fluids
No full textH. Ohta and S. Hamaguchi, Phys. Rev. Lett. 84, 6026, 2000The wave dispersion relations in the fluid phase of Yukawa systems are obtained from molecular dynamics (MD) simulations for a wide range of the parameters. The Yukawa system is a collection of particles interacting through Yukawa (i.e., screened Coulomb) potentials, which can serve as a simple model for dusty plasmas. Our simulations have clearly shown that the transverse wave dispersion has a cutoff at a long wavelength even in the case of weak screening. The MD simulation data are compared with earlier theoretical predictions of the Yukawa dispersion relations and the validity of these theories is clarified. © 2000 The American Physical Society
Molecular dynamics simulation of silicon and silicon dioxide etching by energetic halogen beams
No full textH. Ohta and S. Hamaguchi, Journal of Vacuum Science & Technology A 19, 2373 (2001) https://doi.org/10.1116/1.1385906Molecular dynamics (MD) simulations for silicon and silicon dioxide etching by energetic halogens (F, or Cl), using new sets of interatomic potentials were performed. Sputtering yields for silicon and oxide targets was obtained from the MD simulations. Simultions also showed different target surface structures for fluorine and chlorine beam etching processes, which were accounted for by the difference in atomic size and binding energy between fluorine and chlorine
Classical interatomic potentials for Si-O-F and Si-O-Cl systems
No full textH. Ohta and S. Hamaguchi, J. Chem. Phys. 115, 6679 (2001) https://doi.org/10.1063/1.1400789For Si-O-F and Si-O-Cl systems, Stillinger-Weber (SW)-type potential sets were developed based on interatomic potential energy data obtained from ab initio quantum-mechanical calculations. The aim of the potential development was to perform molecular dynamics (MD) simulations for both silicon and silicon dioxide etching by Cl or F on the same footing. Details of the potential derivation and some sample MD simulation results were also presented
Simulations of trench-filling profiles under ionized magnetron sputter metal deposition
No full textS. Hamaguchi and S. M. Rossnagel, Journal of Vacuum Science & Technology B: Microelectronics and Nanometer Structures Processing, Measurement, and Phenomena 13, 183 (1995) https://doi.org/10.1116/1.587995Numerical simulation results are presented for microscopic profile evolutions of deposited metal films in trench structures under ionized magnetron sputter deposition. The model used for the simulations takes account of the deposition of both ionized and neutral metal species and sputtering (i.e., etching) of the deposited film by the bombardment of metal and inert-gas (such as argon) ions. The evolution of the surface topography is calculated numerically using the shock-tracking algorithm. Numerical results are also compared with experimental observations. A primary application of this metal deposition technique is interconnect metallization on semiconductors
Thermodynamics of strongly-coupled Yukawa systems near the one-component-plasma limit. I. Derivation of the excess energy
No full textS. Hamaguchi and R. T. Farouki, J. Chem. Phys. 101, 9876 (1994) https://doi.org/10.1063/1.467954The excess energy for a system of charged mesoscopic particles or "particulates" immersed in a neutralizing background medium is derived analytically, and is shown to approach that of the classical one-component plasma in the limit of high background temperatures. Examples of such systems, which are known as Yukawa systems due to the form of the interparticle pair potential, include dusty plasmas and colloidal suspensions. The expression for the excess energy allows thermodynamic properties of Yukawa systems to be determined from Monte Carlo or molecular-dynamics simulations. © 1994 American Institute of Physics
Polarization force on a charged particulate in a nonuniform plasma
No full textS. Hamaguchi and R. T. Farouki, Phys. Rev. E 49, 4430, 1994The force on a charged particulate or "dust grain" in a plasma is derived in the presence of a density gradient and an externally applied electric field. The Debye sheath around the particulate is usually deformed (i.e., polarized) under such conditions, and exerts a force on the particulate. This sheath-polarization force is always in the direction of decreasing Debye length, regardless of the sign of the particulate charge. The magnitude of the polarization force is estimated under typical glow discharge conditions. © 1994 The American Physical Society
Liner conformality in ionized magnetron sputter metal deposition processes
No full textS. Hamaguchi and S. M. Rossnagel, Journal of Vacuum Science & Technology B: Microelectronics and Nanometer Structures Processing, Measurement, and Phenomena 14, 2603 (1996) https://doi.org/10.1116/1.588993The conformality of thin metal films (liners) formed on high-aspect-ratio trench structures in ionized magnetron sputter deposition processes is studied numerically and experimentally. The numerical simulator (SHADE) used to predict the surface topography is based on the shock-tracking method for surface evolution. The simulation results are in good agreement with experimentally observed thin-film topography. It is shown that combination of direct deposition and trench-bottom resputtering results in good conformality of step coverages and the amount of the resputtering needed for the good conformality is almost independent of trench aspect ratios. © 1996 American Vacuum Society
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