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Volume 23, Issue 4
Displaying 1-17 of 17 articles from this issue
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A Parallel Algorithm and Its Experimental EvaluationShigeru ANDO1987 Volume 23 Issue 4 Pages 319-325
Published: April 30, 1987
Released on J-STAGE: March 27, 2009
JOURNAL FREE ACCESSThis paper describes a new gradient-based depth recovery algorithm for binocular vision systems with emphasis to the usage in real time measurement environment. Two image sensors are assumed to be matched mechanically. Their common object planes define a reference plane of height on the 3-D object. Extracting a relative height distribution with respect to this plane supplies us extensive information about the object shape near the plane. Approximating local variation of object intensity and describing it using left and right images, we obtained a differential identity with good symmetry which has a meaning that a ratio of a difference image of left and right images against a derivative of a sum image is equal to the disparity. Applying local least squares estimation, we obtained stabilized identity among statistical correlation between the sum and difference images. Advantage of parallel structure of this algorithm is emphasized for applications to dynamical binocular sensor systems. This algorithm was tested with experimental image data. Depth recovery results as well as evaluation of accuracy, resolution, and rangeability are shown.View full abstractDownload PDF (2179K) -
Hideto IWAOKA, Hiroyuki MATSUURA, Tadashi SUGIYAMA, Takaaki HIRATA1987 Volume 23 Issue 4 Pages 326-332
Published: April 30, 1987
Released on J-STAGE: March 27, 2009
JOURNAL FREE ACCESSThis paper describes the Fast Recovery (FR) method for fast-scan Nuclear Magnetic Resonance imaging. The FR method uses a sequence of four radio frequency pulses-alternating selective 90° nutation pulses and nonselective 180° pulses. One free induction decay (FID) signal and one echo signal are detected and averaged to compute a 2-D image. In the modified FR method, extra 180° pulses are applied between 90° pulses to cause refocusing and the resultant spin echo signals are averaged to improve the signal to noise ratio. For the FR and modified FR sequences, the macroscopic magnetization is restored to equilibrium quickly and exactly; scan time can consequently be less than that for conventional pulse sequences, such as used in the saturation recovery method, without any penalty in signal to noise ratio.
This paper derives expressions for the signal to noise ratio, scan time ratio and contrast noise ratio, compares the FR and modified FR methods with the saturation recovery method and presents experimental results for human body images.
In theory and practice, the signal to noise ratio for the FR method is larger than that for the modified FR method. For a given signal to noise ratio the scan time is between one half and one fourth that for the saturation recovery method. The optimum repetition period, Tr, is 0.07∼0.25s for the FR method, and 0.1∼0.5s for the modified FR method. Contrast noise ratio is low for high speed imaging, Tr=0.07∼0.25s, but, high contrast noise ratio image is obtained for Tr>0.5s.View full abstractDownload PDF (1633K) -
Tomomasa SATO, Shigeru IGARASHI1987 Volume 23 Issue 4 Pages 333-340
Published: April 30, 1987
Released on J-STAGE: March 27, 2009
JOURNAL FREE ACCESSThis paper proposes a three-dimensional underwater imaging method of “Synthetic Aperture Image Holography”. The method is based on techniques of computer synthetic aperture and sonar.
The imaging procedures are as follows: (1) A transmitter in the transmitting array projects burst sine ultrasound to a target. (2) The ultrasound reflected from the target is then focused on the receiving array by an acoustic lens. (3) A time series signal of focused ultrasound is detected by the receiving element and is converted to “Image Hologram”. It is the image which contains amplitude, phase and range information of the target. (4) Multiple image holograms are obtained while changing transmitters at different positions in the transmitting array by repeating procedures 1 though 3. (5) A final three-dimensional image is calculated by synthesizing all of these image holograms together.
A method analysis reveals that (1) the method can reduce the amount of calculation needed to obtain the image because the acoustic lens does part of the calculations physically. (2) Lateral resolution of the system is determined by the aperture of the transmitting array not by the lens diameter. It derives from the synthetic aperture calculation and enables us to utilize small diameter lens. (3) Aberration of small diameter lens can be negligible. (4) Since the received image hologram is band limited, intermediate pixels between receiving elements can be interpolated. This reduces the number of receiving ultrasound elements compare to that of image pixels.
“A” mode imaging experiment proved that (5) the experimental lateral and range resolutions are nearly equal to theoretical ones. Constructed imaging system proved that (6) it does not require the complex circuit like phased array, and can be constructed by rather simple circuitry. Three-dimansional images of a target is shown.View full abstractDownload PDF (2320K) -
Heitaro UNO, Kazutaka HIGASHIO, Shuji TAMENAGA1987 Volume 23 Issue 4 Pages 341-346
Published: April 30, 1987
Released on J-STAGE: March 27, 2009
JOURNAL FREE ACCESSMoisture content control is important in the processes of grain drying, processing and storage after harvesting of cereals such as rice, wheat and barley. These automatic systems require the automatic moisture meter which is able to measure non-destructively, continuously, speedy and accurately. We notice the electrostatic capacity method as fulfilling these requirements, but the largest defect in this method is that the measured value is affected by the apparent density. Therefore, when we measured the electrostatic capacity, we used two different high frequencies, and calculate the ratio of them. We named moisture index this Ratio R as a parameter. The effect of the appararent density of cereals became very small by using R and we have obtained a good correlation of R with the moisture. In this peper we describe that we introduced moisture index R from simple models and confirmed experimentally the effectiveness of adopting this index.View full abstractDownload PDF (1193K) -
Masanori SUGISAKA1987 Volume 23 Issue 4 Pages 347-352
Published: April 30, 1987
Released on J-STAGE: March 27, 2009
JOURNAL FREE ACCESSThis paper designs two types of Chandrasekhar-type filters and smoothers (type I and II) by deriving the initial-value solutions to the Fredholm integral equations of the second kind which describe the linear least-squares estimates of stationary stochastic signals in the presence of white Gaussian noises. The covariance kernels of the Fredholm integral equations are assumed to be semi-degenerate form given by the sum of weighted exponential functions. Firstly, the Kailath-Geesey and Casti-Kalaba filtering algorithms which belong to the recursive Wiener filters are briefly reviewed. Secondly, two types of Chandrasekhar-type filters and smoothers are given in connection with these algorithms. Also, several interesting results on type II of the Chandrasekhar-type algorithms are presented.View full abstractDownload PDF (737K) -
Shigeru URIKURA, Akira NAGATA1987 Volume 23 Issue 4 Pages 353-357
Published: April 30, 1987
Released on J-STAGE: March 27, 2009
JOURNAL FREE ACCESSDeadbeat control of the linear discrete-time systems has the specific feature that the error is settled to zero in the finite number of control steps. But on the other hand, a deadbeat control system has an excessive overshoot in the input and/or output transient response for some control objective. Such transient characteristics are not desirable in the practical use of the deadbeat control.
In this paper, we study the design of deadbeat control system which is optimally tuned the transient responses. A pre-compensator is introduced and designed to minimize the quadratic form of the input and output errors. A numerical example is given to show how well the transient responses of deadbeat control system are improved.View full abstractDownload PDF (590K) -
Kazuo AIDA, Toshiyuki KITAMORI1987 Volume 23 Issue 4 Pages 358-363
Published: April 30, 1987
Released on J-STAGE: March 27, 2009
JOURNAL FREE ACCESSThis paper describes some properties and a simplified designing method of the optimal preview servomechanism which was proposed before by the authers. The contents are as follows.
(1) So as to abbreviate the designing time of the preview control coefficient matrix, the algebraic equations are derived.
(2) The relation between the length of preview informations and the optimal value of performance index used for designing the control system is clarified.
(3) It is pointed out that the optimal preview servomechanism involves the PID type one proposed by M. Tomizuka, et al..View full abstractDownload PDF (690K) -
Hiroshi NOGAMI, Hajime MAEDA, Shinzo KODAMA, M. VIDYASAGAR1987 Volume 23 Issue 4 Pages 364-370
Published: April 30, 1987
Released on J-STAGE: March 27, 2009
JOURNAL FREE ACCESSIn this paper we consider a design problem of multivariable high gain feedback systems with robust stability.
High gain feedback control has many advantages for system performances, while it was reported that plant perturbations often cause instability of high gain feedback systems. Hence we discuss a robust stabilization problem of high gain feedback systems.
The plant is assumed to belong to the multiplicative output perturbation class M(P0, r)={P:P=(I+L)P0, ||L(jω)||≤|r(jω)|, ∀ω, where L doesn't change the number of unstable poles}. Here P0 denotes the m×p nominal plant and r denotes, the bound of perturbations. The system contains high gains (not necessarily linear gains) in each feedback loop.
We say a system to be robust positive-real if PC(I+PC)-1 remains stable and positive-real for all plant P belonging to M(P0, r), where C denotes a compensator. Obviously RPR (Robust Positive-Realness) guarantees the stability of the system for all P belonging to M(P0, r) and for all nonlinear gains (while D.C. gains≥1).
We assume rank P0=m, ψ(N0) and ψ(D0) are coprime, where P0=N0D-10 is a right coprime factorization over the ring of stable real rational matrices and ψ(Q) denotes the largest invariant factor of Q. Moreover we assume the roots of |r(jω)|2-1=0 are finitely many and their multiplicities≤2.
Under these conditions there exists a proper compensator which attains RPR and rank P0C=m if and only if the following two conditions are satisfied:
1) ψ(N0) has no finite zeros in the open R.H.P. and has no multiple jω-axis zeros (including j∞), and2)|r(jω)|{=0, for jω-axis zeros of ψ(N0), <1, for jω-axis zeros of ψ(D0), ≤1, elsewhere.
A numerical example is given in order to show that RPR copes with the perturbations which cause instability for LQ optimal control system.View full abstractDownload PDF (873K) -
Shinji HARA, Ryou KONDO, Hideo KATORI1987 Volume 23 Issue 4 Pages 371-378
Published: April 30, 1987
Released on J-STAGE: March 27, 2009
JOURNAL FREE ACCESSPoles and zeros play an important role in control system design. This paper clarifies the properties of zeros of a single input-single output discretized system composed of a sampler and a zero-order hold. It is shown that the property that the number of real zeros between any two real poles is even or odd is preserved for the discretized system with any sampling period which assures all the poles of the continuous controlled object lie in the primary strip of s-plane. This property is also true for a sampled system considering any computational time delay and the sampled system has at least an unstable limiting zero for small sampling periods. Sufficient conditions, which guarantee the sampled system has only stable zeros or an unstable zero regardless of the sampling period, are presented using the derived properties.View full abstractDownload PDF (952K) -
Masayuki FUJITA, Etsujiro SHIMEMURA1987 Volume 23 Issue 4 Pages 379-385
Published: April 30, 1987
Released on J-STAGE: March 27, 2009
JOURNAL FREE ACCESSThis paper is concerned with the integrity conditions for linear multivariable feedback systems. Integrity is defined as the property such that the closed-loop system remains stable against an arbitrary feedback-loop failure. A new class of matrices, called U-matrix, is introduced, by investigating the properties of the matrices whose all principal minors are units in the set of proper stable rational functions. Based on U-matrix, a necessary and sufficient condition for integrity is given with a stable plant. The result shows that integrity is ensured if and only if the sensitivity matrix is U-matrix as well as the controller being stable. Moreover, using the properties of U-matrix, some sufficient conditions for integrity are derived. It is shown that, if the sensitivity matrix is either strictly positive real or generalized diagonal dominant with all diagonal elements in the set of the units, then integrity is established provided the closed-loop system, as well as the controller, is stable. In terms of the return difference matrix and the closed-loop transfer function matrix, similar results are also derived.View full abstractDownload PDF (926K) -
Young-Taek HYUN, Seiichi SHIN, Shigenori OKUBO1987 Volume 23 Issue 4 Pages 386-393
Published: April 30, 1987
Released on J-STAGE: March 27, 2009
JOURNAL FREE ACCESSThis paper presents a finite spectrum assignment (f.s.a.) procedure for the single-input linear systems with commensurate time-delays. For this purpose, an algorithm is given to construct the feedback for f.s.a. and it is shown that the algorithm is availlable under the spectral controllability of the system. Therefore, it turns out that the system is finite spectrally assignable if and only if it is spectrally controllable. The result is consistent with the existing one.
The algorithm consists of the following three steps.
(1) Construct a feedback formally by a state feedback with the future states.
(2) Construct a predictor for the future states.
(3) Realize the feedback for f.s.a. by the substitution of the predictor to that constructed in step (1).
In paticular, for step (2) a sufficient condition to predict the future states is given and an algorithm to construct the predictor is also presented. Finally, it is proven that the spectrum of the closed-loop system is in fact assigned to be a finite set by using the resulting feedback.View full abstractDownload PDF (861K) -
Hisao MIYANO1987 Volume 23 Issue 4 Pages 394-399
Published: April 30, 1987
Released on J-STAGE: March 27, 2009
JOURNAL FREE ACCESSThis paper describes a new parameter estimation method for weighted euclidean distance model, in which individual configurations obtained from multidimensional scaling are directly fitted to some common space. The new method is based on an alternating least squares estimation method, and is easily extended for more general weighted euclidean model. Validity of the method is illustrated by using and analyzing a set of artificial data and color perception data.View full abstractDownload PDF (774K) -
Hideto IWAOKA, Takaaki HIRATA, Hiroyuki MATSUURA1987 Volume 23 Issue 4 Pages 400-406
Published: April 30, 1987
Released on J-STAGE: March 27, 2009
JOURNAL FREE ACCESSPure T1, T2 and proton density (ρ) images can be computed from three or more different NMR images. Computed images can be useful for several reasons: a) they are objective, since they are independent of pulse sequence and scan parameters. b) arbitrary composite images can be synthesized from computed images. c) biochemical information can be obtained from relaxation times, so quantitative diagnosis is possible using T1 and T2 images. For these reasons, several methods of producing computed images have been tried.
However, with these methods, there are several practical problems such as large systematic error and long total scan time. This paper describes how several sets of NMR pulse sequences and scan parameters were investigated, keeping total scan time constant, to find which of them gave computed images with best resolution and minimum systematic error for a given scan time.
Pulse sequences and scan parameters were optimized to yield minimum variance of computed images, using the law of error propagation, for a given range of T1, T2 and ρ. We found that theoretically the combination Inversion Recovery 3 Spin Echo and Saturation Recovery 4 Spin Echo pulse sequence gave the best compromise between scan time and resolution.
The effect of slice profile and errors in RF pulses-causes of systematic error-were analyzed in order to find ways to remove or reduce them.
Using this method computed T1, T2 and ρ images were obtained for the human head and for various phantoms. Computed values agreed closely with values measured using analytical methods. We conclude from these results that the combination Inversion Recovery 3 Spin Echo and Saturation Recovery 4 Spin Echo pulse sequence gives the best compromise between scan time, resolution and error.View full abstractDownload PDF (1540K) -
A Spectral Responsivity Distribution Measurement of Visible and Near Infrared Radiation ThermometersAkira ONO, Fumihiro SAKUMA, Susumu HATTORI1987 Volume 23 Issue 4 Pages 407-409
Published: April 30, 1987
Released on J-STAGE: March 27, 2009
JOURNAL FREE ACCESSDownload PDF (419K) -
Joe IMAE, Kyojiro HAKOMORI1987 Volume 23 Issue 4 Pages 410-412
Published: April 30, 1987
Released on J-STAGE: March 27, 2009
JOURNAL FREE ACCESSDownload PDF (365K) -
Young-Taek HYUN, Seiichi SHIN, Shigenori OKUBO1987 Volume 23 Issue 4 Pages 413-415
Published: April 30, 1987
Released on J-STAGE: March 27, 2009
JOURNAL FREE ACCESSDownload PDF (298K) -
Minoru HAYASE, Satoshi KANEKO1987 Volume 23 Issue 4 Pages 416-418
Published: April 30, 1987
Released on J-STAGE: March 27, 2009
JOURNAL FREE ACCESSDownload PDF (264K)
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