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 10.18926/15393
FullText URL Mem_Fac_Eng_OU_30_2_15.pdf
Author Oka, Hisao| Fujiwara, Shiro|
Abstract An estimation of muscle fatigue is very important study and many laboratory researchers had done actively in this field. The excellent measurement and analysis methods, however, have not established yet. The aim of this study was to investigate the muscle fatigue of low back, caused by sitting on the vehicle seat for a long time. The muscle viscoelasticity and the EMG (Electromyogram) were measured. The authors proposed the objective muscle fatigue index that was obtained from the result of PCA (Principal Component Analysis) by using the measured varlables. The objective muscle fatigue index suggests an adequate correlation with the subjective fatigue on the vehicle seat.
Publication Title Memoirs of the Faculty of Engineering, Okayama University
Published Date 1996-03-29
Volume volume30
Issue issue2
Start Page 15
End Page 20
ISSN 0475-0071
language 英語
File Version publisher
NAID 120002307965
JaLCDOI 10.18926/46968
FullText URL mfe_37_1_011_014.pdf
Author Totsuji, Chieko| Limant, Muhammad S.| Tsuruta, Kenji| Totsuji, Hiroo|
Abstract A theoretical approach which has been successful in reproducing results of molecular-dynamics simulations on dusty plasmas is applied to estimate the screening length and the electric charge of two-dimensional dust crystals of melamine particles in the discharge chamber experiment. It has been found that the screening length is of the same order of magnitude as the inter-particle distance and the electric charge decreases on increasing number density of dust particles.
Publication Title Memoirs of the Faculty of Engineering, Okayama University
Published Date 2002-11
Volume volume37
Issue issue1
Start Page 11
End Page 14
ISSN 0475-0071
language 英語
File Version publisher
NAID 80015784816
JaLCDOI 10.18926/47003
FullText URL mfe_36_1_091_106.pdf
Author Kanatani, Kenichi| Ohta, Naoya|
Abstract We present a theoretically optimal linear algorithm for 3-D reconstruction from point correspondences over two views. We also present a similarly constructed optimal linear algorithm for 3-D reconstruction from optical flow. We then compare the performance of the two algorithms by simulation and real-image experiments using the same data. This is the first impartial comparison ever done in the sense that the two algorithms are both optimal, extracting the information contained in the data to a maximum possible degree. We observe that the finite motion solution is always superior to the optical flow solution and conclude that the finite motion algorithm should be used for 3-D reconstruction.
Publication Title Memoirs of the Faculty of Engineering, Okayama University
Published Date 2001-12
Volume volume36
Issue issue1
Start Page 91
End Page 106
ISSN 0475-0071
language 英語
File Version publisher
NAID 120003497029
JaLCDOI 10.18926/47002
FullText URL mfe_36_1_079_090.pdf
Author Kanatani, Kenichi|
Abstract We first present an improvement of Kanatani's subspace separation [8] for motion segmentation by newly introducing the affine space constraint. We point out that this improvement does not always fare well due to the effective noise it introduces. In order to judge which solution to adopt if different segmentations are obtained, we present two criteria: one is the standard F test; the other is model selection using the geometric AIC of Kanatani [7] and the geometric MDL of Matsunaga and Kanatani [13]. We test these criteria doing real image experiments.
Publication Title Memoirs of the Faculty of Engineering, Okayama University
Published Date 2001-12
Volume volume36
Issue issue1
Start Page 79
End Page 90
ISSN 0475-0071
language 英語
File Version publisher
NAID 120003497028
JaLCDOI 10.18926/15419
FullText URL Mem_Fac_Eng_OU_29_2_49.pdf
Author Ahmed, Anis| Taniguchi, Shinji| Wada, Osami| Wang, Ming| Koga, Ryuji|
Abstract For weakly guiding dielectric waveguides, the eigenmode field distributions are calculated numerically with a simple algorithm. In this numerical method, the transverse sampling space can be chosen arbitrarily, and hence a narrow waveguide can be analyzed. The field satisfying scalar wave equation is expressed by the discrete Fourier transform and the mode eigenvalues and eigenfunctions are calculated by solving an eigenvalue equation numerically. The validity of this method is checked for 2-D waveguides having step and parabolic or square index distributions. It is found that for the well guided TE modes of the slab waveguide, the accuracy of this method is remarkably good, but some discrepancies are found if the mode is near cut off. In the problems where the normalized guide index b is small, caution should be taken in applying the results of this numerical method.
Publication Title Memoirs of the Faculty of Engineering, Okayama University
Published Date 1995-03-27
Volume volume29
Issue issue2
Start Page 49
End Page 55
ISSN 0475-0071
language 英語
File Version publisher
NAID 120002307858
JaLCDOI 10.18926/15438
FullText URL Mem_Fac_Eng_OU_28_1_61.pdf
Author Takeshita, Yuji| Kohno, Iichiro|
Abstract Knowledge of the unsaturated soil hydraulic properties is essential requirement for prediction of seepage flow and contaminant transport through the vadose zone. Unfortunately, these parameters are usually time consuming and expensive to measure in the field and laboratory. At the present condition, there are few data accumulation for Japanese soils. In this paper, van Genuchten's closed-form expressions are described to estimate unsaturated soil hydraulic properties. To evaluate the adequacy of these expressions, comparisons are performed between observed and calculated unsaturated hydraulic properties for typical Japanese soils.
Publication Title Memoirs of the Faculty of Engineering, Okayama University
Published Date 1993-11-30
Volume volume28
Issue issue1
Start Page 61
End Page 69
ISSN 0475-0071
language 英語
File Version publisher
NAID 120002307801
JaLCDOI 10.18926/15384
FullText URL Mem_Fac_Eng_OU_30_1_99.pdf
Author Wang, Ming| Wada, Osami| Koga, Ryuji|
Abstract A cylindric mirror was used, in place of a parabolic mirror, to collimate the crescent blue laser beam radiated from the Cerenkov SHG in channel waveguide configuration. The cylindric mirror radius is requested to be twice the focal length of the parabolic mirror. The focusing effect of the cylindric mirror in collimation can be compensated by slightly lifting the mirror in its normal direction. Under the condition that the mirror was declined by 5.56° and lifted by 25 μm, we got the collimated beam with divergence angle less than 1.3 mrad. In the focusing experiment, the collimated beam was focused with spotsize of 1.8 μm. The details on the analysis and experiment are reported.
Publication Title Memoirs of the Faculty of Engineering, Okayama University
Published Date 1995-12-28
Volume volume30
Issue issue1
Start Page 99
End Page 110
ISSN 0475-0071
language 英語
File Version publisher
NAID 120002307418
JaLCDOI 10.18926/17833
FullText URL Mem_Fac_Eng_OU_43_27.pdf
Author Totsuji, Hiroo|
Abstract When the Coulomb coupling between fine particles becomes sufficiently strong in fine particle plasmas, the isothermal compressibility of the whole system diverges and we have a phase separation and an associated critical point. Experimental conditions of fine particle plasmas, densities and temperatures of components and the fine particle size, are obtained corresponding to characteristic parameters around the critical point and the dependency on ion species and other factors is discussed.
Publication Title Memoirs of the Faculty of Engineering, Okayama University
Published Date 2009-01
Volume volume43
Start Page 27
End Page 31
ISSN 1349-6115
language 英語
File Version publisher
NAID 120002308947
JaLCDOI 10.18926/14086
FullText URL Mem_Fac_Eng_OU_41_1_63.pdf
Author Kanatani, Kenichi| Sugaya, Yasuyuki|
Abstract The convergence performance of typical numerical schemes for geometric fitting for computer vision applications is compared. First, the problem and the associated KCR lower bound are stated. Then, three well known fitting algorithms are described: FNS, HEIV, and renormalization. To these, we add a special variant of Gauss-Newton iterations. For initialization of iterations, random choice, least squares, and Taubin’s method are tested. Numerical simulations and real image experiments and conducted for fundamental matrix computation and ellipse fitting, which reveals different characteristics of each method.
Publication Title Memoirs of the Faculty of Engineering, Okayama University
Published Date 2007-01
Volume volume41
Issue issue1
Start Page 63
End Page 72
ISSN 0475-0071
language 英語
File Version publisher
NAID 120002308585
JaLCDOI 10.18926/47029
FullText URL mfe_36_2_083_089.pdf
Author Watanabe, Tetsushi| Wada, Osami| Koga, Ryuji| Toyota, Yoshitaka| Miyashita, Takuya|
Abstract Suppression of common-mode current is important to achieve electromagnetic compatibility of high-speed and high-density electronic circuits. The authors have focused on the common mode current flowing on a printed circuit board (PCB) to explain the excitation mechanism. A narrow ground pattern in microstrip structure excites common-mode current. In the previous paper, the authors explained the mechanism of common mode generation by means of "current division factor" for simple PCBs. The estimated radiation from a simple PCB agreed well with measured one. In this paper, the authors extend the theory to be applied to generalize ground structure. The validity of the theory is confirmed by comparing the measured radiation and the estimated value using the common-mode model for a test PCB. The estimated radiation agrees well with the measured one within 3 dB up to 900 MHz.
Publication Title Memoirs of the Faculty of Engineering, Okayama University
Published Date 2002-03
Volume volume36
Issue issue2
Start Page 83
End Page 89
ISSN 0475-0071
language 英語
File Version publisher
NAID 120003497051
JaLCDOI 10.18926/15414
FullText URL Mem_Fac_Eng_OU_26_1_27.pdf
Author Tomita, Eiji| Nsunge Felix Chintu| Hamamoto, Yoshisuke|
Abstract Distributions of hydrogen gas concentration in a suddenly started, single shot hydrogen gas jet issuing from a 1 mm diameter injector into still air were measured using laser interferometry method. This unsteady, turbulent free jet flow has also been calculated using the two-equation, high Reynolds number version of k-ε turbulence model and hybrid scheme for treating combined diffusion and convection in the SIMPLE algorithm. The injection pressure was 0.5 MPa for which predicted and measured temporal jet tip penetration distributions indicate that the jet discharged into still air at Mach 0.25. The level of agreement between present prediction and measurement is good in some regions and poor in others.
Publication Title Memoirs of the Faculty of Engineering, Okayama University
Published Date 1991-11-30
Volume volume26
Issue issue1
Start Page 27
End Page 41
ISSN 0475-0071
language 英語
File Version publisher
NAID 120002307648
JaLCDOI 10.18926/17851
FullText URL Mem_Fac_Eng_OU_43_108.pdf
Author Nekado, Kenta| Kato, Hidehiro| Nogami, Yasuyuki| Morikawa, Yoshitaka|
Abstract Recently, pairing-based cryptographies such as ID-based cryptography and group signature have been studied. For fast pairing calculation, not only pairing algorithms but also arithmetic operations in extension field must be efficiently carried out. The authors show efficient arithmetic operations of extension field for Xate pairing especially with Freeman curve.
Publication Title Memoirs of the Faculty of Engineering, Okayama University
Published Date 2009-01
Volume volume43
Start Page 108
End Page 112
ISSN 1349-6115
language 英語
File Version publisher
NAID 120002308904
JaLCDOI 10.18926/14153
FullText URL Mem_Fac_Eng_39_1_56.pdf
Author Sugaya, Yasuyuki| Kanatani, Kenichi|
Abstract We present a new method for extracting objects moving independently of the background from a video sequence taken by a moving camera. We first extract and track feature points through the sequence and select the trajectories of background points by exploiting geometric constraints based on the affine camera model. Then, we generate a panoramic image of the background and compare it with the individual frames. We describe our image processing and thresholding techniques.
Publication Title Memoirs of the Faculty of Engineering, Okayama University
Published Date 2005-01
Volume volume39
Issue issue1
Start Page 56
End Page 62
ISSN 0475-0071
language 英語
File Version publisher
NAID 120002308594
JaLCDOI 10.18926/19953
FullText URL Mem_Fac_Eng_OU_44_1.pdf
Author Nagai Shinji| Umeda Ryosuke| Tsuruta, Kenji|
Abstract In this paper, we investigate a light-confinement phenomenon in the structure which has triangular latice composed of Double NeGative Metamaterial (DNGM). In geometrical optics consideration, this structure is expected to confine lights completely by sequential refractions in the structure. We demonstrate it by using the two dimensional finite-difference time-domain simulations. We introduce Drude-Lorentz model for dielectric and magnetic dispersion of the material at optical frequencies. We analyze quantitatively the effects of energy loss in the DNGM on the light-confinement efficiency.
Publication Title Memoirs of the Faculty of Engineering, Okayama University
Published Date 2010-01
Volume volume44
Start Page 1
End Page 6
ISSN 1349-6115
language 英語
File Version publisher
NAID 120002309117
JaLCDOI 10.18926/17829
FullText URL Mem_Fac_Eng_OU_43_16.pdf
Author Kurose Tomoyuki| Tsuruta, Kenji| Totsuji, Chieko| Totsuji, Hiroo|
Abstract The finite-difference time-domain (FDTD) method has been applied to the calculation of the phonon band structure of two-dimensional (2D) phononic crystals, consisting of metal cylinders placed periodically in liquid. By comparing several combinations of materials for metal cylinder and liquid, we analyze the dependence of the band structures on sound speed and density of liquid media. Moreover, the negative refraction of the acoustic waves is observed at the interfaces between phononic crystal slab and the liquid. We find that an acoustic“lens effect”with the slab appears due to the negative refractions. The relationship between the focal intensity in the lens effect and the band structure is discussed.
Publication Title Memoirs of the Faculty of Engineering, Okayama University
Published Date 2009-01
Volume volume43
Start Page 16
End Page 21
ISSN 1349-6115
language 英語
File Version publisher
NAID 120002308928
JaLCDOI 10.18926/15412
FullText URL Mem_Fac_Eng_OU_26_1_21.pdf
Author Nozu, Shigeru| Inaba, Hideo|
Abstract A numerical study is performed for the facilitated diffusion of carbon-dioxide in an ultrapure water film flowing downward along a vertical surface. The model adopted for the present work includes the effects of the reaction rate for the hydration of CO(2)in a liquid. Comparison of the total concentration of CO(2) for different film thickness indicates that the effects of the hydration is more remarkable for the thinner liquid film.
Publication Title Memoirs of the Faculty of Engineering, Okayama University
Published Date 1991-11-30
Volume volume26
Issue issue1
Start Page 21
End Page 26
ISSN 0475-0071
language 英語
File Version publisher
NAID 120002307958
JaLCDOI 10.18926/19618
FullText URL Mem_Fac_Eng_OU_33_1_59.pdf
Author Fujihara Yutaka| Osaki, Hirokazu|
Abstract In this paper, we propose a method to solve simultaneously facility layout problem and scheduling problem. About a initial random layout planning, the production scheduling and the transportation scheduling of AGV are obtained by using priority rules. From the obtained transportation scheduling, the critical transportation and the closeness rating are obtained. Facility layout is renewed by the combined procedure of genetic algorithm and tabu search in order to reduce the material handling cost. By using this renewed facility layout, the production scheduling and the transportation scheduling of AGV are also revised until no further improvement is possible.
Publication Title Memoirs of the Faculty of Engineering, Okayama University
Published Date 1998-11-30
Volume volume33
Issue issue1
Start Page 59
End Page 64
ISSN 0475-0071
language 英語
File Version publisher
NAID 120002308989
JaLCDOI 10.18926/46953
FullText URL mfe_38_1-2_061_071.pdf
Author Kanatani, Kenichi| Sugaya, Yasuyuki|
Abstract The Tomasi-Kanade factorization for reconstructing the 3-D shape of the feature points tracked through a video stream is widely regarded as based on factorization of a matrix by SVD (singular value decomposition). This paper points out that the core principle is the affine camera approximation to the imaging geometry and that SVD is merely one means of numerical computation. We first describe the geometric structure of the problem and then give a complete programming scheme for 3-D reconstruction.
Publication Title Memoirs of the Faculty of Engineering, Okayama University
Published Date 2004-03
Volume volume38
Issue issue1-2
Start Page 61
End Page 71
ISSN 0475-0071
language 英語
File Version publisher
NAID 80016889443