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Volume 34, Issue 4
Displaying 1-10 of 10 articles from this issue
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Nozomi SUGIURA, Masashi NISHIGAKI, Yuji IKEDA, Tsuyoshi NAKAJIMA1998 Volume 34 Issue 4 Pages 285-292
Published: April 30, 1998
Released on J-STAGE: March 27, 2009
JOURNAL FREE ACCESSThe flow patterns and flow characteristics in a no-sidewall fluidic gas flowmeter were investigated by LDV measurements. A phase locking technique using pressure signal detected at the nozzle outlet was used for calculating velocity variation over a phase at each point. Two dimensional flow visualization was succeeded in terms of flow vector and vorticity at five flow rates. These results revealed that the essential flow patterns were almost the same regardless of flow rate. Vortices were shed in the wake behind the target synchronized with the nozzle jet oscillation at Re≥300. Vortex shedding was not observed at approximately Re=150. Frequency dependency on flow rate was also investigated, showing that the Strouhal number was its maximum at approximately Re=300. Under the Re of 300, the vortex shedding was suggested to cause the fluctuation of Strouhal number. The dependency of Strouhal number on Reynolds number was successfully explained by velocity distribution variation in the nozzle between Re of 300 and 800, but other factor such as turbulence or CD must be considered at the higher Re than 800.View full abstractDownload PDF (2059K) -
Takashi OHNISHI, Tetsuo TAKAHASHI, Yoshiya YOSHIDA1998 Volume 34 Issue 4 Pages 293-298
Published: April 30, 1998
Released on J-STAGE: March 27, 2009
JOURNAL FREE ACCESSA method for counting the number of specific microbes is important for food and medical manufacturing plants to ensure biological quality and to keep safety of their products. A conventional method for counting microbes most widely employed is a “ager culture method”; it requires a cultivation operation which takes too much time, usually two to several days. For avoiding such a disadvantage, there have been proposed, as a technique of indirect determination of the population of microbes, in which apply relations between bacterial concentration and physical or biological properties, e.g., ultrasonic attenuation, respiration activity, electric capacitance, etc. However, those method can apply only at a high population of microbes, and it is impossible to count the target sort of microbes in distinction from the others in the liquid sample.
A fluorescent dye labeled antibody combines selectively with the specific cell of microbe. The cell conjugated with this dye emits a certain deviation of fluorescence upon exposure to excitation light. Using this fluorescent dye labeled antigen-antibody reaction, we investigated the counting system composed of micro flow cell and photometric system including a pulse counter for detecting fluoresce emitted as individual luminous point from the fluorescent product in each of the microbes floating in the sample. The aim of our system is to get advantages of rapidity, accuracy and easiness to measure continuously even at a low population of microbes.
Experimental research of the counting of Lactobacillus Fermentum (a sort of Lactic-acid microbe) was examined as an example of the counting method proposed in this paper. From the test results, it proved that this method is effective to count the population of wanted specific microbe even at a low population of 2∼4-digit figures (102∼104)/ml, taking only about 4 hours a sample.View full abstractDownload PDF (2250K) -
Satoru OKAMOTO1998 Volume 34 Issue 4 Pages 299-304
Published: April 30, 1998
Released on J-STAGE: March 27, 2009
JOURNAL FREE ACCESSThe tube-bank exhaust gas economizer can be usually considered as a series of tubes arranged in a rectangular duct. The tube arrays in cross flow sometimes excite the acoustical vibrations of sound fields in the duct of the exhaust gas economizer. It is very important, for practical applications, to understand the conditions of the acoustical resonances in the duct with the tube bundles.
A staggered array of closely paced rigid tubes has been tested, in a exhaust gas economaizer of varying the flow velocity, to investigate the conditions under which acoustical resonances do or do not materialize. Among the aspects which have been investigated are: the Strouhal numbers at which flow periodicities occur; the relation between these Strouhal numbers and those at which acoustical resonances occur.
The resonances occur when the frequencies of the flow periodicities inside the array coincide with those of the acoustical modes. At resonances, the intense pure tone noises, which may reach 120dB, are produced. When the shedding frequency of the vortex formed in the wake of the flow behind the individual tubes happens to be near the natural frequency of the gas column perpendicular to the flow and the tube axis, a strong transverse acoustical oscillation of the gas column is excited.
Acoustical resonance in the economizer tube arrays has been suppressed by detuning the resonance with baffles that shift the acoustic natural frequency upwards. We have successfully employed a single baffle to suppress resonance.View full abstractDownload PDF (1263K) -
Effect of Longitudinal Tube SpacingSatoru OKAMOTO1998 Volume 34 Issue 4 Pages 305-310
Published: April 30, 1998
Released on J-STAGE: March 27, 2009
JOURNAL FREE ACCESSA staggered array of closely packed rigid tubes has been tested, in a wind tunnel of varying the flow velocity, to investigate the conditions under which acoustical resonances do or do not materialize. Among the aspects which have been investigated are: the Strouhal numbers at which flow periodicities occur; the relation between these Strouhal numbers and those at which acoustical resonances occur; the effect of the Reynolds numbers and the longitudinal tube spacing on the occurrence of acoustical resonance.
This investigation has shown that:
1. The acoustic resonance can be excited at a frequency well removed from that of vortex shedding. The results also show evidence of both phenomena existing, simultaneously at different frequencies.
2. The acoustic resonances behavior is consistent with that of a self excited system.
3. An alternative model of this phenomenon provides a better procedure for avoiding these resonances in closely packed tube banks.
On the basis of these findings and the findings from a similar investigation into vortex induced tube vibration it is proposed that tube vibration and acoustic vibration are treated as different mechanisms. Hence the guidelines presented in this paper should be followed to avoid the occurrence of acoustic vibration.View full abstractDownload PDF (1092K) -
Yoshiyuki SHIRAKAWA, Kiyomi HORIKOSHI1998 Volume 34 Issue 4 Pages 311-317
Published: April 30, 1998
Released on J-STAGE: March 27, 2009
JOURNAL FREE ACCESSThis paper describes the possibility of multi-parameter measurements to meet the requirements for more precise and stable control of a blast furnace. A basic concept of such measurements is to make use of multi-radiations of neutrons and γ-rays, and to obtain multi-types of information on conditions of materials (iron ore and coke) inside the blast furnace.
A prototype gauge was assembled and examined which consisted of a radiation source of 252Cf, a neutron moderator, a lead shield, a bismuth germanate detector, a stainless casing and a control unit. Laboratory experiments showed that the gauge could measure the quantities to be essential to estimate material conditions. In practice, it clearly distinguished between iron ore and coke layers, and at the same time measured bulk density of iron contained in iron ore by counting thermal neutron capture γ-rays from iron. It also gave the information on material bulk density by detecting Compton scattered γ-rays from material, i.e. iron ore and coke. Finally, reducibility of iron ore was calculated by using both bulk densities. Relative accuracy of measurements was reasonable in practical use.
The possibility of realization of the gauge has been proved and the on-line trial will be expected in the near future.View full abstractDownload PDF (3754K) -
Shuanghui HAO, Teruo TUSJI1998 Volume 34 Issue 4 Pages 318-325
Published: April 30, 1998
Released on J-STAGE: March 27, 2009
JOURNAL FREE ACCESSThis paper presents a new method of designing an adaptive nonlinear controller for a class of single-input/single-output systems, where the input is premultiplied by the product of an unknown parameter vector and a known nonlinear function vector and is input to the system through the constant coefficient vector. The systems are assumed to be unknown feedback linearizable continuous-time systems with a general relative degree. The control objective is for the output of the plant to track a reference trajectory. The linearizing feedback control law is defined in the terms of the estimated states and parameters. The state estimation are provided by the nonlinear adaptive observer. The unknown parameters are estimated by using an augmented tracking error and the known nonlinear functions. A local convergence theorem is given on the the convergence of the tracking error. The simulation result of an example is shown to confirm appropriateness of the design of the adaptive nonlinear controller.View full abstractDownload PDF (1431K) -
Hidefumi KOBATAKE, Masayuki MURAKAMI1998 Volume 34 Issue 4 Pages 326-332
Published: April 30, 1998
Released on J-STAGE: March 27, 2009
JOURNAL FREE ACCESSThe Iris Filter is a filter which evaluates the degree of convergence of gradient vectors in the neighborhood of pixel of interest. If the pixel of interest is located in a rounded convex region, almost all gradient vectors of the intensity point to its summit and the output of the iris filter takes the maximum at the summit. Such characteristics are useful to detect rounded convex regions with weak contrast against complex background. The detection of cancerous tumors on X-ray images is a typical example of the application of the iris filter. This paper presents theoretical characteristics of the iris filter. Primary results are as follows.
1) Outputs of the iris filter are 1 and 1/π at the summit and the boundary of rounded convex region, respectively.
2) Outputs of the iris filter are 2/π and 1/π at the center and the boundary of semicylindrical convex region, respectively.
3) The optimal region of support of the iris filter coincides with boundaries of rounded convex region and semicylindrical convex region.
4) The filter output depends on only directions of gradient vectors. Therefore, rounded convex regions with weak contrast against their background are enhanced and their boundary shapes are almost preserved.
These characteristics are shown theoretically and experimentally.View full abstractDownload PDF (2363K) -
Toshihiro AONO, Kenjiro FUJII, Shintaro HATSUMOTO, Takayuki KAMIYA1998 Volume 34 Issue 4 Pages 333-339
Published: April 30, 1998
Released on J-STAGE: March 27, 2009
JOURNAL FREE ACCESSThis paper deals with a estimation method of vehicle position using differential GPS, a fiber optic gyro and wheel encoders. The estimated position must be accurate enough to be used for vehicle control. To realize this accuracy, the following factors must be considered.
(1) The delay and scarcity of GPS data.
(2) The drift of the gyro.
(3) The inconstancy of the travel distance per encoder pulse due to the differential mechanism and slip of wheels.
(4) The effect of the position of the GPS antenna on position estimation.
We propose an observation model of GPS, a fiber optic gyro and wheel encoders, which considers these four factors. A position estimation method is developed on the basis of this observation model. A prototype of autonomous mower was produced to evaluate the position estimation method. The relation between the performance of the mower and the GPS accuracy is discussed in terms of the parallelism, the uniformity of the space, and the straightness. The experimental results show that the merit of using GPS data is remarkable for maintaining the parallelism. If GPS is more accurate than 1m, it is shown that using GPS improves the uniformity of the spaces. We can have the prospect for mowing all over the ground if the overlap is 0.2m and the GPS accuracy is 1m.View full abstractDownload PDF (2432K) -
Takao TOMARU1998 Volume 34 Issue 4 Pages 340-342
Published: April 30, 1998
Released on J-STAGE: March 27, 2009
JOURNAL FREE ACCESSIn this paper a new approach is proposed for the algebraic solution of the Exact Model Matching. The input and output feedback of the SISO system are introduced from the partial state feedback containing the augmented rational polynomial function which is reducible. The algebraically designed input and output feedback system has the property suitable for the adjustment. The simulation shows good step responses which are stable in spite of the deviation from the nominal performance.View full abstractDownload PDF (475K) -
Byeongdeok YEA, Tomoyuki OSAKI, Kazunori SUGAHARA, Ryosuke KONISHI1998 Volume 34 Issue 4 Pages 343-345
Published: April 30, 1998
Released on J-STAGE: March 27, 2009
JOURNAL FREE ACCESSA new operation method of a semiconductor gas sensor is proposed to improve the gas selectivity and temperature-humidity characteristics of the sensor. In the method the heater voltage of the sensor is changed periodically, named periodic operation, for a certain time interval after inflammable gases were introduced. The method is examined in discriminating five kinds of inflammable gases with a three-layered BP neural network, and high discrimination rate (average 98%) is achieved.View full abstractDownload PDF (500K)
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