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Volume 24, Issue 10
Displaying 1-20 of 20 articles from this issue
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Hiroaki TANAKA1988 Volume 24 Issue 10 Pages 1003-1009
Published: October 30, 1988
Released on J-STAGE: March 27, 2009
JOURNAL FREE ACCESSThis paper deals with signal wave ringing caused by the frequency characteristic of an antenna system in underground probing radar, which is one of important factors to affect the performance of a radar-based pipe locator. Evaluation constants of signal wave ringing caused by the frequency characteristic of an antenna system were defined. On the assumption that the radar antenna is a band pass filter which consists of a quadratic low pass filter and high pass filter, they were calculated and evaluated as a function of cut off frequency of low pass filter, high pass filter and dumping factor by means of computer simulation. As the result, it was found that the suitable frequency band of a radar antenna is 10MHz-300MHz (at the dumping constant of 1.0) or 10MHz-600MHz (at the dumping constant of 0.2) to obtain less ringing. Next, radar antenna could get desirable frequency band by means of resistor loading, and a radarbased pipe locator was manufactured with these antennas for field trials. The system has tested at actual fields in Tokyo gas supplying area and it is found that the system is effective in about 80% of the area.View full abstractDownload PDF (2640K) -
Fan LIU, Masaru UCHIYAMA, Kyojiro HAKOMORI1988 Volume 24 Issue 10 Pages 1010-1015
Published: October 30, 1988
Released on J-STAGE: March 27, 2009
JOURNAL FREE ACCESSIn this paper, we present a new method for the estimation of the velocity profile of unsteady laminar fluid flow in the entrance region of a circular pipe, in order to measure the flow rate in the pipe. The method is a model-based method which uses a nonlinear dynamic model of the flow and is a unified method which can be applied to both outside and inside of the entrance region.
The dynamic model is derived, initially, by linearizing the Navier-Stokes equation for the axial direction, and secondly, by lumping the distributed parameters of the linear equation. The linearization is done by using the fact that the entrance flow satisfies linear equations at its boundaries and yields a linear partial differential equation with an unknow parameter. The lumping is done by applying the finite element method.
The extended Kalman filter technique is then applied to the linear lumped parameter model with an unknow parameter, and a nonlinear filter to estimate the velocity profile on the pipe section at any point along the pipe is obtained.
The filter is implemented on a numerical simulator and on a real system. Both implementations are executed to yield accurate estimations of the velocity profile. In the real system the velocity profile is measured by a beam scanning laser Dopplar velocimeter which was developed originally in the authors' laboratory, and is compared with the estimated profile. As a result the effectivenss of the filter is shown.View full abstractDownload PDF (867K) -
Shigeru ANDO1988 Volume 24 Issue 10 Pages 1016-1022
Published: October 30, 1988
Released on J-STAGE: March 27, 2009
JOURNAL FREE ACCESSA set of image feature operators which are derived from curvatures of local correlation function, i.e., sums of products of grayness derivatives, is described and examined. First, a quadratic surface defined by the curvatures are related to local grayness properties which lead to nonlinear operators being sensitive to 1) overall variations, 2) equidirectional variations, 3) unidirectional variations, 4) orientation, and 5) maximum unidirectional variations. Then combining these operators, we obtain dimensionless and normalized expressions which are independent to contrast and resolution of image features. Basicly, they act as statistic operators to extract 6) overall, 7) equidirectional, and 8) unidirectional normalized variations of image textures. By functional analysis, however, they are shown to respond also in deterministic and exclusive manner to structural features such as blobs, edges, lines, corners, intersections, etc. Results show unique characteristics of the operators such as independence to clearness, normalized outputs, classified response on directivity, and stable orientation outputs.View full abstractDownload PDF (3014K) -
Hiro YAMASAKI, Satoshi HONDA1988 Volume 24 Issue 10 Pages 1023-1028
Published: October 30, 1988
Released on J-STAGE: March 27, 2009
JOURNAL FREE ACCESSBoth vortex flowmeters and fluidic flowmeters form a family of the hydrodynamic oscillator type flowmeters, since the oscillation of wakes in vortex flowmeters and that of jets in fluidic flowmeters have geometrical and hydrodynamic complementarity, and there exist a unified model describing fluid motion in the hydrodynamic oscillator type flowmeter. Furthermore, topological isomorphism between the flow fields of both flowmeters leads to a new fluidic oscillator which consists of a jet and a bluff cylinder. The objectives of the research are to clarify the mechanism of the oscillation and to apply the oscillator to a flowmeter. The relationship between the velocity at the inlet nozzle and the oscillation frequency for the various combinations of geometric parameters were measured with the air as operating fluid. The results are summarized as follows:
1. A bluff cylinder-so called target-is indispensable to the oscillator; the less the bluffness, the higher the frequency.
2. The oscillation frequency is almost inversely proportional to the distance between the target and the nozzle.
3. A downstream contraction increases the frequency and stabilizes the oscilation; the nearer and the narrower the contraction, the higher the frequency.
4. The wider the jet, the higher the frequency.
These results together with flow visualization studies conclude that the degree of the deflection of the jet from the natural reattachment streamline mainly determines the oscillation frequency. Since the deflection depends on the position and the bluffness of the target, proposed oscillator is a hybrid of fluidic and vortex flowmeters. The experimental results also show that the oscillator shares the merits of hydrodynamic oscillator type flowmeters and is applicable to low flowrate measurement.View full abstractDownload PDF (2005K) -
Norihide YAMADA, Yoshirou NAGAI, Sadao FUJIMURA1988 Volume 24 Issue 10 Pages 1029-1032
Published: October 30, 1988
Released on J-STAGE: March 27, 2009
JOURNAL FREE ACCESSWe propose a new method for radiation thermometry to determine the true temperature without a priori knowledge about the value of emissivity. This method uses a nonlinear emissivity modification attributed to the multiple-reflection induced by a half mirror put closely and parallel to the object in the optical path of radiation. Direct and indirect (through the half mirror) measurements of the radiation from the object give us the value of the true temperature and the emissivity of the object simultaneously. The validity of this method was confirmed empirically for various samples at the temperature from 300°C to 400°C. The samples had the emissivity from 0.1 to 0.9 and surfaces of different scattering properties. The estimation error was less than 10°C except for a sample with very low emissivity and highly scattering surface.View full abstractDownload PDF (554K) -
Hideki YOSHITOMI, Tsutomu WADA1988 Volume 24 Issue 10 Pages 1033-1039
Published: October 30, 1988
Released on J-STAGE: March 27, 2009
JOURNAL FREE ACCESSThe cavitation in a vortex diode gives significant influences on a fluidic-pump performance. Its effect is more important in forward-flow state. Therefore it is a crucial aspect to clear the cavitation phenomena in the vortex diode in order to design the fluidic pump.
This paper describes the forward-flow cavitation of the vortex diode. A Zobel-type vortex diode was used as the test diode. According to a preliminary test, the cavitations were observed at both an axial nozzle and a tangential nozzle, and they affect each other. Therefore, experiments were performed in distinct three phases to make clear each cavitation. In phase-I and phase-II, we tried to examine the axial-nozzle cavitation and tangential-nozzle one respectively. And then, in phase-III, an overall test was performed to obtain their mutual interferences.
Through the three phases, states of the cavitations were observed carefully and the cavitation onset conditions were measured for individual cavitations. Then the cavitation onset patterns were analysed graphically and one design criterion for improvement was suggested.
The results obtained here are as follows:
1) The cavitation is generated in the axial nozzle at first, and follows in the tangential one. The cavitation onset leads to a choking state immediately.
2) The axial-nozzle cavitation shows an aspect of fixed cavitation. The tangential-nozzle cavitation consists of three types of cavitation such as travelling, fixed and vortex ones in compliance with down-stream pressure level. The onset cavitation-numbers of those cavitations show the tendencies to have the constant values individually in the experiments.
3) The pressure condition to avoid the cavitation occurrence has been given by a simple analysis.
4) It has been clarified that the value of the ratio of diameters of axial nozzle to tangential one should be 0.87 to improve the cavitation characteristics.View full abstractDownload PDF (2042K) -
Ho Gil LEE, Hideaki KANOH, Sadao KAWAMURA, Fumio MIYAZAKI, Suguru ARIM ...1988 Volume 24 Issue 10 Pages 1040-1047
Published: October 30, 1988
Released on J-STAGE: March 27, 2009
JOURNAL FREE ACCESSIn order to realize accurate positioning or tracking of flexible one-link arm, the rigid-body motions and elastic behaviors have to be controlled simultaneously. Moreover, we must reach such a goal by using only one joint-actuator. In this case, the stability analysis of the controlled system is very important, since the properties of distributed parameters of the arm can lead to potential instability. In this paper, a model of one link flexible arm rotating in horizontal plane is derived by applying Hamilton's principle, and then, the stability of the system with some linear control laws is analyzed by Mikhailov's theorem.
Some interesting results are as follows:
1) Conventional local PD control schemes for rigid-link robots always make the flexible system stable.
2) Under the additional feedback of elastic modes by using vibration-detecting sensors, the system becomes conditionally stable. It is profoundly related to the location of the sensor and gain tuning.View full abstractDownload PDF (1012K) -
Wataru KASE, Katsutoshi TAMURA1988 Volume 24 Issue 10 Pages 1048-1055
Published: October 30, 1988
Released on J-STAGE: March 27, 2009
JOURNAL FREE ACCESSIn a model reference adaptive control system (MRACS) design for multi input multi output (MIMO) systems, an interactor matrix plays an important role. Many efforts have been devoted to eliminate pre-information on a system transfer matrix to obtain the interactor. In this paper we consider the derivation of an algorithm to obtain an interactor, called G-interactor, for MRACS design. The G-interactor is a natural extension of the interactor for the exact model matching and needs a few pre-information which is reasonable for unknown system transfer matrix. The G-interactor has a minimum degree of diagonal elements and a minimum number of elements in off diagonal polynomials.View full abstractDownload PDF (899K) -
Tetsuo SHIOTSUKI, Shigeyasu KAWAJI1988 Volume 24 Issue 10 Pages 1056-1063
Published: October 30, 1988
Released on J-STAGE: March 27, 2009
JOURNAL FREE ACCESSDescriptor systems is a generalization of the state-space model, and is a mixture of dynamic and static (nondynamic) parts. Of particular interest are the static parts. There are two types of static parts; the one is a part associated with the dynamical behavior. The other is a purely static part and it cause an ambiguity of the concepts on the structure of descriptor system. For example, we have two kinds of definitions of controllability and observability. One method of removing this ambiguity is to eliminate the purely static part and to get a minimal representation. Several reserchers have tackled this problem, but the traditional methods depend on Kronecker decomposition and are not necessarily suitable for the control system design, since Kronecker decomposition include numerically unstatble algorithms.
In this paper, we propose a new and numerically oriented algorithm to eliminate the purely static parts. At first, an eliminating procedure based on restricted system equivalence is introduced, and some features are clarified. Secondly the static parts are newly characterized in a geometric way, and the property in the aspect of solvability, controllability, and observability are discussed. Finally a numerically oriented algorithm is presented by using singular value decomposition, and the effectiveness is demonstrated in the problem of inverse system of descriptor form.
The proposed method in this paper is simple and numerically statble, so it is effective in application of control system design and analysis.View full abstractDownload PDF (1042K) -
Masami IWATSUKI, Masayuki KAWAMATA, Tatsuo HIGUCHI1988 Volume 24 Issue 10 Pages 1064-1070
Published: October 30, 1988
Released on J-STAGE: March 27, 2009
JOURNAL FREE ACCESSThis paper proposes a newly defined sensitivity called statistical sensitivity in continuous time state-space linear systems. The statistical sensitivity is given by using a virtual stochastic system of which coefficients and input signal are white processes. The necessary and sufficient condition for the mean square asymptotical stability is given by analyzing the convergence of the statistical sensitivity. This condition determines the upper bound of variance of coefficient variations that guarantees the stability of the system. If the coefficient variations are very small, the approximated statisitical sensitivity is represented by the controllability and observability Gramians. The approximated statistical sensitivity can be minimized under an assumption that the all elements of coefficient matrices vary. The minimum sensitivity structures are equal to balanced realizations in the wide sense. To show the validity of statistical sensitivity, the various sensitivities of three structures are compared using a numerical example. The numerical example shows that a balanced realization has much lower sensitivity than a controllablity canonical realization and a parallel realization. Furthermore, the balanced realization allows the large variance of coefficient variations that guarantees the stability.View full abstractDownload PDF (976K) -
Yoshimichi YONEZAWA, Kazunori ITOH1988 Volume 24 Issue 10 Pages 1071-1076
Published: October 30, 1988
Released on J-STAGE: March 27, 2009
JOURNAL FREE ACCESSA handy Braille reading device for various types of Braille has been developed for the blind who find difficulties in reading the Braille.
Recently, the adventitious blind are increasing in number by the reason of increase of traffic accidents and diabetes. They find great difficulties in learning Braille, especially in reading Braille because their sense of finger tips become dull with age.
The device is designed so that it can work just instead of finger tips by which the born blind read Braille, and is composed of a sensor and a personal computer with vocal output. At the sensor, the small projections which compose a Braille character are detected by a combination of phototransistors and optical fiber array, and are converted to electric signals. The location of projections are measured by a small rotary encorder. The signals are analized by the computer to vocalize the character.
For some types of Braille, reading speed of 10cm/s comparable to reading speed by finger tips of normal blind was achieved.View full abstractDownload PDF (1227K) -
Koichiro DEGUCHI1988 Volume 24 Issue 10 Pages 1077-1083
Published: October 30, 1988
Released on J-STAGE: March 27, 2009
JOURNAL FREE ACCESSThis paper describes a new method to extract features of contour of a figure using its curvature changes. The local curvature maxima and minima along with the contour line are powerful features to characterize the contour of a figure, which correspond to convex and concave vertices, respectively. While the curvature is originally defined in terms of derivatives, for a digital figure, they are defined by using differences of line directions at two points with an appropriate distance scales, because a digital curve is given as a series of points.
However, when some vertices locally neighbour on the contour line, false curvatures are calculated with some range of the scales. Where two convex vertices nearly neighbour, for example, a false larger maximal value is calculated if too large scale is used. But, employing some multiple scales and comparing the results, such false curvature maxima appear to change their values in peculiar forms according to the locations and angles of vertices included in that part.
In this method, a set of curvatures with various scales, which is called a multi-scale curvatures, is calculated. Analyzing the curvature changes with respect to the multiple scales, therefore, the features of the original contour, such as the locations and angles of vertices, are extracted from the multi-scale curvatures. The “view-field resolution” for the analysis of features of figures are determined automatically, for one by one figure and its part.View full abstractDownload PDF (1027K) -
Makoto TAKEYA1988 Volume 24 Issue 10 Pages 1084-1088
Published: October 30, 1988
Released on J-STAGE: March 27, 2009
JOURNAL FREE ACCESSThis paper presents a formalization of cluster extraction algorithms for an asymmetric fuzzy data, i.e. a fuzzy digraph. First, this paper classifies a fuzzy digraph into seven categories of fuzzy connectedness-1) strongly complete, 2) weakly complete, 3) bilaterally connected, 4) unilaterally connected, 5) strongly connected, 6) weakly connected, and 7) totally ordered digraphs. Second, extraction algorithms of subgraphs are presented according to respective 1)-6) connectivity categories. Then, it is shown that each cluster extraction algorithm operationally results in a clique extraction algorithm. Third, a minimum weakly complete digraph is defined and then an extraction algorithm based on totally ordered category is presented.View full abstractDownload PDF (711K) -
Masaaki MURATA1988 Volume 24 Issue 10 Pages 1089-1091
Published: October 30, 1988
Released on J-STAGE: March 27, 2009
JOURNAL FREE ACCESSThe first Japanese geodetic satellite“AJISAI” was launched on August 12, 1986, which is dedicated primarily to satellite laser ranging (SLR). This paper describes methods, as well as analysis results, which enable the AJISAI orbit to fit to the SLR data at the residual level of better than 20cm (rms).View full abstractDownload PDF (503K) -
Keizo FUJIBAYASHI, Nobuharu AOSHIMA1988 Volume 24 Issue 10 Pages 1092-1094
Published: October 30, 1988
Released on J-STAGE: March 27, 2009
JOURNAL FREE ACCESSExtraction of voice signal from periodic noise is performed by DSP system. An adaptive filter predicts periodic noise, while residual voice appears in error signal These processings are made by specially designed computer which uses digital signal processor (DSP).View full abstractDownload PDF (282K) -
Takehiro MORI1988 Volume 24 Issue 10 Pages 1095-1096
Published: October 30, 1988
Released on J-STAGE: March 27, 2009
JOURNAL FREE ACCESSA necessary and sufficient condition is derived for convex combinations of two stable polynomials to retain the stability. Based on this result, a series of sufficient conditions for the same property are also obtained.View full abstractDownload PDF (173K) -
Hiroaki OZAKI, Akira MOHRI, Tatsuyuki SHIMADZU1988 Volume 24 Issue 10 Pages 1097-1099
Published: October 30, 1988
Released on J-STAGE: March 27, 2009
JOURNAL FREE ACCESSThis paper presents a new method to generate a collision-free path of a mobile object. Obstacle spaces are artificially contracted to obtain an initial collision-free path and then the path is iteratively modified to avoid the obstacle spaces which are gradually restored.View full abstractDownload PDF (406K) -
Tadashi EGAMI, Takeshi TSUCHIYA1988 Volume 24 Issue 10 Pages 1100-1102
Published: October 30, 1988
Released on J-STAGE: March 27, 2009
JOURNAL FREE ACCESSThis paper describes initial value compensation for discrete-time optimal servosystem based on error system method. The effectiveness of initial value compensation is examined for full state feedback control system with feedforward compensation and partial state feedback control system.View full abstractDownload PDF (353K) -
Kazunobu YOSHIDA, Hisashi KAWABE1988 Volume 24 Issue 10 Pages 1103-1105
Published: October 30, 1988
Released on J-STAGE: March 27, 2009
JOURNAL FREE ACCESSThe VSS design problem for a linear system with bounded control has been investigated using a quadratic performance index, the value of which can be more lowered by logically switching admissible gains {k0, k1, …, kp} than by the single gain k0.View full abstractDownload PDF (313K) -
Kazunori NAMIKI, Hidefumi KOBATAKE1988 Volume 24 Issue 10 Pages 1106-1108
Published: October 30, 1988
Released on J-STAGE: March 27, 2009
JOURNAL FREE ACCESSThis paper describes a study on fractal analysis of X-ray images of pneumoconiosis. It is shown that local fractal dimension increases monotonically as the profusion of pneumoconiosis opacities increases. And experimental results of automatic classification of pneumoconiosis show the effectiveness of fractal feature parameters.View full abstractDownload PDF (392K)
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