JaLCDOI 10.18926/15488
FullText URL Mem_Fac_Eng_OU_25_1_37.pdf
Author Bouzidi, Moncef| Koga, Ryuji| Wada, Osami| Kagawa, Naoki| Hai, Xu| Kosaka, Megumi| Sano, Hiroya|
Abstract Is proposed a tunable diode laser absorption spectrometer system which employs a pulsed current to drive the diode laser still implementing a second-harmonic detection methods enhancing a signal to noise up to 104 times that the case without it. This system affords the lead-salt diode laser a higher operating temperature which allows a more compact deep cooling system. A principle is based on employing a gated integrator between the preamplifier and the lock-in amplifier. Investigations are made on the optimum selection of the gating aperture time interval as determined by response time of the infrared detector and the pulse width of the laser driving current.
Publication Title Memoirs of the Faculty of Engineering, Okayama University
Published Date 1990-12-14
Volume volume25
Issue issue1
Start Page 37
End Page 50
ISSN 0475-0071
language 英語
File Version publisher
NAID 120002307549
JaLCDOI 10.18926/15495
FullText URL Mem_Fac_Eng_OU_24_2_31.pdf
Author Oka, Hisao| Isayama Yoshiharu| Nakauchi Makoto| Yamamoto, Tatsuma|
Abstract A small vibration on the body surface is expected to apply to a clinical examination of the autonomic nervous system. The vibration cannot be found by the naked eyes. It is called a microvibration (MV) or a minor tremor (MT). It is not cleared out why and how the MV occurs, but many papers about its occurrence and clinical application have been published. In this study, the typical spectrum of MV and the various causes of MV occurrence are studied. The relationships of MV with heart rate, muscle contraction and MV are discussed. The power spectrum of MV is obtained by using an autoregressive model.
Publication Title Memoirs of the Faculty of Engineering, Okayama University
Published Date 1990-03-29
Volume volume24
Issue issue2
Start Page 31
End Page 40
ISSN 0475-0071
language 英語
File Version publisher
NAID 120002307725
JaLCDOI 10.18926/19591
FullText URL Mem_Fac_Eng_OU_31_2_21.pdf
Author Oka, Hisao| Nakamura, Takahiko|
Abstract In evaluating the stiffness of skin surface, internal structures such as bone and muscle often affect the measurements. In the present paper, acoustic random vibration is used to estimated the viscoelasticity of a silicone-gel model. This viscoelasticity, which includes two different stiffness strata, is first estimated using a mechanical impedance spectrum, which describes the relation between the depth and viscoelasticity of internal objects. This method is applied to the depth of a silicone-gel tumor model measured by ultrasound imaging and the viscoelasticity of internal gel can be accurately estimated.
Publication Title Memoirs of the Faculty of Engineering, Okayama University
Published Date 1997-03-28
Volume volume31
Issue issue2
Start Page 21
End Page 27
ISSN 0475-0071
language 英語
File Version publisher
NAID 120002309105
JaLCDOI 10.18926/19592
FullText URL Mem_Fac_Eng_OU_31_2_29.pdf
Author Oka, Hisao| Ohshima, Masakazu|
Abstract Knee replacement arthroplasty is indicated for the patient with advanced knee pain, knee deformation, and knee functional disorder. The aim of this study was to estimate loosening after a knee replacement arthroplasty. Loosening is measured by a frequency response function, and mobility by random vibration. The modal parameters for the knee joint are obtained by applying a modal analysis to the frequency response function. The values decrease as the knee joint prosthesis loosened. These parameters serve as an index for the condition between a thighbone and the prosthesis. The various indexes will greatly clarify the stage of advance in the loosening of knee-joint prostheses.
Publication Title Memoirs of the Faculty of Engineering, Okayama University
Published Date 1997-03-28
Volume volume31
Issue issue2
Start Page 29
End Page 37
ISSN 0475-0071
language 英語
File Version publisher
NAID 120002309172
JaLCDOI 10.18926/19634
FullText URL Mem_Fac_Eng_OU_32_15.pdf
Author Mori, Masahiro| Oka, Hisao|
Abstract In a stiffness estimation of living body, an internal structure under the skin influences the measured results. Because a different stiffness of body caused by bones and muscles is obtained. In this paper, by using a measurement system of mechanical impedance, the relations between a viscoelasticity and a distance from the surface of silicone-gel model is calculated. This relation is applied to silicone-gel tumor model and a shape and a viscoelasticity of semi-sphere silicone-gel tumous are estimated. The obtained results are expressed as a reconstructed 3-D image of shape / viscoelasticity. The revised curve-fitting of mechanical impedance and the cancellation of peripheral vibration influence are proposed in order to increase an estimation acccuracy.
Publication Title Memoirs of the Faculty of Engineering, Okayama University
Published Date 1998-04-20
Volume volume32
Issue issue1-2
Start Page 15
End Page 22
ISSN 0475-0071
language 英語
File Version publisher
NAID 120002309047
JaLCDOI 10.18926/19663
FullText URL Mem_Fac_Eng_OU_33_2_39.pdf
Author Yanagi Makoto| Oka, Hisao|
Abstract The acousicmyogram (AMG) is a mechanical phenomenon recorded at the surface of an active muscle. It is used to monitor force production, fatigue, and contractile properties of muscle. In this study, the new electrode with accelerometer for electrostimulation and acoustic detection. It consists of Ag-AgCl active electrode and solid-gel annular groud, and a very light piezoresistive accelerometer. The recorded AMG waveform depends on the pulse amplitude and duration of stimulation current and its lag from the electroatimulation is about 7 ms. The strengh-duration (S-D) curve (the threshold current for stimulation vs. pulse duration) describes the excitability of muscle. The left forearm is electrostimulated by using the same electrode and the muscle vibration (AMG) is recorded with accelerometer. During the muscle fatigue, the S-D curve changes and the current threshold increases under the same pulse duration. The rheobase of S-D curve increases gradually but the chronaxie hardly changes during muscle fatigue.
Publication Title Memoirs of the Faculty of Engineering, Okayama University
Published Date 1999-04-27
Volume volume33
Issue issue2
Start Page 39
End Page 44
ISSN 0475-0071
language 英語
File Version publisher
NAID 120002309185
JaLCDOI 10.18926/19666
FullText URL Mem_Fac_Eng_OU_33_2_45.pdf
Author Yamada Nobuya| Oka, Hisao|
Abstract It is difficult to evaluate a biomechanical properties quantitatively. The authors developed the measurement system of biomechanical properties formerly but it is on a large scale because of the use of personal computer. In this study, the portable measurement system of biomechanical impedance/mobility is developed. To establish a rapid measurement, a random vibration is adopted in input signal. The system consists of the measuring probe, amplifier, and a note-typed personal computer. The measurement probe is developed newly, and has an overall length of 9 ㎝ (without a handle) and a total weight of about 500 g. The measurement program is also developed and is available to any computer which is worked under MS DOS compatible in Windows 95/98 operating system. The biomechanical spectra of thigh, temple and forehead are obtained and they show three typical spectrum patterns.
Publication Title Memoirs of the Faculty of Engineering, Okayama University
Published Date 1999-04-27
Volume volume33
Issue issue2
Start Page 45
End Page 50
ISSN 0475-0071
language 英語
File Version publisher
NAID 120002309193
JaLCDOI 10.18926/15501
FullText URL Mem_Fac_Eng_OU_24_2_67.pdf
Author Nago, Hiroshi| Maeno, Shiro|
Abstract Many hydraulic structures are damaged by under flood flow and storm waves year after year. Many cases of dike and breakwater failure are caused by the suck out of sand from behind the revetment. This type of failure will be in close relation to the dynamic behavior of sand bed around the revetment. In this paper, from this point of view, we investigated the basic characteristics of such sand movement by small model tests and tried to explain the hydro- and soil-mechanical mechanism of this phenomenon theoretically.
Publication Title Memoirs of the Faculty of Engineering, Okayama University
Published Date 1990-03-29
Volume volume24
Issue issue2
Start Page 67
End Page 78
ISSN 0475-0071
language 英語
File Version publisher
NAID 120002307928
JaLCDOI 10.18926/14058
FullText URL Mem_Fac_Eng_OU_42_44.pdf
Author Ogawa Takafumi| Tsuruta, Kenji| Totsuji, Chieko| Totsuji, Hiroo| Hiroshi Iyetomi|
Abstract To analyze vibrational properties of Si crystal with a single charge-neutral vacancy, we perform large-scale simulations based on tight-binding molecular-dynamics method. Vibrational modes and frequencies are obtained by diagonalizing dynamical matrix within a harmonic approximation. Results indicate that there exist vibrational modes spatially localized around the vacancy and large frequency shifts associated with the localized modes contribute significantly to reduction of the vibrational free energy.
Publication Title Memoirs of the Faculty of Engineering, Okayama University
Published Date 2008-01
Volume volume42
Issue issue1
Start Page 44
End Page 47
ISSN 0475-0071
language 英語
File Version publisher
NAID 120002308412
JaLCDOI 10.18926/14059
FullText URL Mem_Fac_Eng_OU_42_48.pdf
Author Totsuji, Chieko| Miyake Takashi| Nakanishi Kenta| Tsuruta, Kenji| Totsuji, Hiroo|
Abstract Based on the mapping introduced by the classical-map hypernetted-chain (CHNC) method, classical numerical simulations, Monte Carlo and molecular dynamics, have been applied to the twodimensional electron fluid and the results are compared with those of quantum Monte Carlo simulations hitherto reported. It is shown that polarization properties of the ground state obtained by the diffusion Monte Carlo method are reproduced within the accuracy of quantum simulations by both of two mapping functions for the quantum temperature which have been proposed within the CHNC method. These results may serve as the basis of numerical simulations based on the CHNC method which are applicable to finite non-periodic systems like quantum dots and systems at finite temperatures.
Publication Title Memoirs of the Faculty of Engineering, Okayama University
Published Date 2008-01
Volume volume42
Issue issue1
Start Page 48
End Page 52
ISSN 0475-0071
language 英語
File Version publisher
NAID 120002308425
JaLCDOI 10.18926/14061
FullText URL Mem_Fac_Eng_OU_42_56.pdf
Author Miyake Takashi| Totsuji, Chieko| Nakanishi Kenta| Tsuruta, Kenji| Totsuji, Hiroo|
Abstract We analyze the ground state of the two-dimensional quantum system of electrons confined in a parabolic potential with the system size around 100. We map the system onto a classical system on the basis of the classical-map hypernetted-chain (CHNC) method which has been proven to work in the integral-equation-based analyses of uniform unbounded systems and then apply classical numerical simulations. We find that the confined system undergoes the transition to the spin polarized state with the decrease of the average density and the corresponding critical value is as low as rs ∼ 0.3 in terms of the usual rs parameter estimated for the average density. As the ground state for given value of the rs parameter, our data give the critical value for the transition around 20 which is consistent with the known possibility. The advantage of our method is a direct applicability to geometrically complex systems which are difficult to analyze by integral equations. The application to the structure like quantum dots reported here is the first example of such applications.
Publication Title Memoirs of the Faculty of Engineering, Okayama University
Published Date 2008-01
Volume volume42
Issue issue1
Start Page 56
End Page 59
ISSN 0475-0071
language 英語
File Version publisher
NAID 120002308633
JaLCDOI 10.18926/14119
FullText URL Mem_Fac_Eng_OU_40_1_31.pdf
Author Ogawa, Takafumi| Totsuji, Chieko| Tsuruta, Kenji| Totsuji, Hiroo|
Abstract We analyze the melting of spherical Yukawa clusters by Monte Carlo simulations. Spherical clusters are expected to be found in dusty plasmas in an isotropic environment such as microgravity and serve as a model for classical clusters. We obtain the specific heat through fluctuations of the potential energy and identify its peak as the transition temperature. Melting temperatures are compared with those of bulk Yukawa systems and it is confirmed that the melting temperature increases and approaches the bulk value with the increase of the system size.
Publication Title Memoirs of the Faculty of Engineering, Okayama University
Published Date 2006-01
Volume volume40
Issue issue1
Start Page 31
End Page 35
ISSN 0475-0071
language 英語
File Version publisher
NAID 120002308329
JaLCDOI 10.18926/14120
FullText URL Mem_Fac_Eng_OU_40_1_36.pdf
Author Uchida, Atsushi| Totsuji, Chieko| Tsuruta, Kenji| Totsuji, Hiroo|
Abstract We present a Stochastic-Difference-Equation (SDE) approach to long time-scale molecular dynamics (MD) simulations, which are required for nanosecond-scale phenomena. In this method, the MD trajectory in a fixed time period is obtained as a stationary solution of an action functional based on an error accumulation of the equation of motion along the path, thus reducing the problem to a boundary-value problem, instead of an initial-value problem in the ordinary MD method. We apply the method to formation processes of Cu thin film via nanocluster deposition onto a substrate. The applicability of the SDE algorithm to the problem and the effects of the choice of SDE parameters on the optimization processes of configuration pathway are examined.
Publication Title Memoirs of the Faculty of Engineering, Okayama University
Published Date 2006-01
Volume volume40
Issue issue1
Start Page 36
End Page 39
ISSN 0475-0071
language 英語
File Version publisher
NAID 120002308517
JaLCDOI 10.18926/14121
FullText URL Mem_Fac_Eng_OU_40_1_40.pdf
Author Takashi, Miyake| Totsuji, Chieko| Tsuruta, Kenji| Totsuji, Hiroo|
Abstract The electron system of arbitrary degeneracy can be mapped onto a classical system where electrons of the same spin are assigned an additional interaction and the effect of degeneracy is taken into account through an imaginative temperature. We apply this method to electrons in quantum dots modeled as two-dimensional electron liquid confined in a finite domain by a harmonic potential. We analyze distribution functions by molecular dynamics instead of solving integral equations which are not so useful in the case without translational invariance.
Publication Title Memoirs of the Faculty of Engineering, Okayama University
Published Date 2006-01
Volume volume40
Issue issue1
Start Page 40
End Page 43
ISSN 0475-0071
language 英語
File Version publisher
NAID 120002308268
JaLCDOI 10.18926/14150
FullText URL Mem_Fac_Eng_39_1_46.pdf
Author Kadono, Keisuke| Totsuji, Chieko| Tsuruta, Kenji| Totsuji, Hiroo|
Abstract We present a real-space, polynomial-expansion approach to electron dynamics in nanostructured semiconductors. The Chebyshev expansion method is employed for efficient calculation of timeevolution of single-electron wave function. Details of the formulation are described. The method is applied to the electron transport in nanostructured semiconductors such as Si nanowires. The mean-square displacement and diffusivity of electron in Si chains are obtained as functions of length of the chains. The results show clearly ballistic behavior of electron in the pure Si chain.
Publication Title Memoirs of the Faculty of Engineering, Okayama University
Published Date 2005-01
Volume volume39
Issue issue1
Start Page 46
End Page 51
ISSN 0475-0071
language 英語
File Version publisher
NAID 120002308231
JaLCDOI 10.18926/14152
FullText URL Mem_Fac_Eng_39_1_52.pdf
Author Kanamori, Katsuya| Totsuji, Chieko| Tsuruta, Kenji| Totsuji, Hiroo|
Abstract Thermal behavior of Coulomb clusters in a three dimensional confining potential is investigated by molecular dynamics simulations for system sizes of 1,000 to 20,288 ions. The specific heat of the system of shell-structured 20,000 ions is peaked almost at the same temperature as the system of bcc-structured 20,288 ions with much sharper structure for the latter. The diffusion coefficient and the peak to valley ratio of the two-dimensional pair distribution function on the outermost shell are obtained both as a function of temperature. The rotational movement of each shell in the system of 104 ions is observed.
Publication Title Memoirs of the Faculty of Engineering, Okayama University
Published Date 2005-01
Volume volume39
Issue issue1
Start Page 52
End Page 55
ISSN 0475-0071
language 英語
File Version publisher
NAID 120002308445
JaLCDOI 10.18926/15348
FullText URL Mem_Fac_Eng_OU_35_21.pdf
Author S.kovalenko, Volodymyr| Uno, Yoshiyuki| Okamoto, Yasuhiro| Anyakin, M.| Lutay, A.| Shubul, Khaled Al.|
Abstract In electric power industry, there is a problem of achieving stable joint in different components using high productive and efficient technologies. One type of these components is packages of slices for magnetic circuit of electric motors, transformers etc., which need reliable means for their fixing. Laser welding is proposed to solve this problem as an alternative for existing technologies. The development of the laser welding process is presented based on process simulation, study of heat history and comparison with experimental results. Laser beam additional scanning technique is proposed to improve the quality and efficiency of the joining operation.
Publication Title Memoirs of the Faculty of Engineering, Okayama University
Published Date 2001-03-27
Volume volume35
Issue issue1-2
Start Page 21
End Page 28
ISSN 0475-0071
language 英語
File Version publisher
NAID 120002307424
JaLCDOI 10.18926/15358
FullText URL Mem_Fac_Eng_OU_35_63.pdf
Author Shinomiya Shigeru| Totsuji, Chieko| Tsuruta, Kenji| Totsuji, Hiroo|
Abstract We present a theoretical study of Si(1-x)Ge(x) alloys based on tight-binding molecular dynamics (TBMD) calculations. First, we introduce a new set of nonorthogonal tight-binding parameters for silicon and germanium based on the previous work by Menon and Subbaswamy [Phys. Rev. B 55, 9231 (1997); J. Phys: Condens. Matter 10, 10991 (1998)]. We then apply the method to structural analyses of Si(1-x)Ge(x) alloys. The equilibrium volume and atomic structure for a given x are obtained by the TBMD method. We also calculate the bulk modulus B, elastic constants C(11), C(12) and C(44) as a function of x. The results show that the moduli vary monotonically, but nonlinearly, between the values of Si crystal and Ge crystal. The validity of the results is also discussed.
Publication Title Memoirs of the Faculty of Engineering, Okayama University
Published Date 2001-03-27
Volume volume35
Issue issue1-2
Start Page 63
End Page 75
ISSN 0475-0071
language 英語
File Version publisher
NAID 120002307673
JaLCDOI 10.18926/15361
FullText URL Mem_Fac_Eng_OU_35_77.pdf
Author Kishimoto Tokunari| Totsuji, Chieko| Tsuruta, Kenji| Totsuji, Hiroo|
Abstract In order to perform the large-scale molecular dynamics simulation of the Yukawa system, a mathematical expression for molecular dynamics using the fast multipole method is described. The model simulations are also performed to test the performance of our implementation of the FMM.
Publication Title Memoirs of the Faculty of Engineering, Okayama University
Published Date 2001-03-27
Volume volume35
Issue issue1-2
Start Page 77
End Page 95
ISSN 0475-0071
language 英語
File Version publisher
NAID 120002307940
JaLCDOI 10.18926/15382
FullText URL Mem_Fac_Eng_OU_35_207.pdf
Author Nakanishi, Toru| Fujiwara Toru|
Abstract In the group signature scheme with a trusted party, a verifier can determine whether or not a signature is made by a member of the group, but cannot identify the member who signed the signature. In case of dispute later on, the signer can be identified by the trusted party. However, for efficient group signature schemes proposed so far, removing a member from the group can be not efficiently performed. In this paper, a group signature scheme with an easy membership canceling is proposed. By sending a request to use a resource together with the group signature on it to the manager of the resource, the manager can control anonymous accesses to the resource. In such an application, the proposed group signature scheme is suitable for canceling of the access privilege.
Publication Title Memoirs of the Faculty of Engineering, Okayama University
Published Date 2001-03-27
Volume volume35
Issue issue1-2
Start Page 207
End Page 212
ISSN 0475-0071
language 英語
File Version publisher
NAID 120002307232