ABSTRACTS
Psychological Determinants of Brightness of a Space -Perceived
Strength of Light Source and Amount of Light in the Space-
Taiichiro ISHIDA and Yasuo OGIUCHI
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Which lighting attributes determine the brightness of
a room space? We considered the perceived strength of
the light source and the perceived amount of light in
the space as potential determinants. We examined the relations
between the actual brightness of the space and these two
perceptions. In the first experiment, subjects evaluated
the strength of the light source and the amount of light
in the space using reference matching method. The results
were consistent among the subjects, indicating they judged
each of the two lighting attributes by some common criteria.
In the second experiment, the brightness of the space,
the strength of the light source, and the amount of light
in the space of a model box were evaluated using the magnitude
estimation method under various illumination conditions.
We found that the brightness of the space was closely
correlated with the perceived amount of light but not
with the perceived strength of the light source. These
results should prove useful in constructing a model for
quantitatively estimating the brightness of a space.
KEYWORDS: brightness of a space, perception of lighting
environment |
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Effect of Cathode Heating on Relation between
Crest Factor and Cathode Fall Voltage
Tadao UETSUKI, Noriyuki TAGUCHI and Wataru NODA
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The operating life of a fluorescent lamp is determined
by the life of its cathode, which depends on how quickly
the cathode loses its oxide coating. There are two mechanisms,
vaporizing and sputtering, in this process. The sputtering
is affected by the current crest factor (CCF) because
the electron current is determined by the cathode temperature
and the electric field of the cathode fall:
When CCF is high, the cathode temperature cannot follow
variations in the current because of thermal inertia.
As a result, the cathode fall voltage (CFV) increases
in order to supply the flow of peak electron current,
which leads to heavy sputtering. The equation for electron
current also shows that CFV can be reduced by heating
the cathode auxiliarily if CCF is high. Examination of
the relations among CCF, CFV, and the cathode temperature
measured by the indirect method showed that
(1)The peak CFV increases as the CCF becomes higher when
the cathode is not heated.
(2)The peak CFV can be reduced by heating the cathode
if the CFV is high.
(3)The heating power needed to reduce the CFV is small
enough for the practical circuit.
KEYWOARDS: crest factor, cathode fall voltage, cathode
heating |
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A Fundamental Approach to Detecting the
Light Source Position in a Cubical Room by Using Light Sensors
and a Database
Yuji HONDA, Yasuyuki IWATA, Etsushi IKI, Naoyuki SHINOMURA and
Masayoshi NAGATA
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A method is described for detecting a light-source position
that can be used to find partial discharges in gas-insulated
switchgears as an indication of a fault. Comparing the
illuminances measured by light sensors to those in a database
gives information about the light-source position. The
database is built beforehand using illuminance distributions,
computed by the Monte Carlo method, for each given light
source in a lighting space. In the database, the set of
measured illuminances for a light source is treated as
a position in a fictitious space or plane. This method
was tested for a simple cubical room by using the Monte
Carlo method to compute illuminances created on sensors
by test light sources and by estimating the accuracies
of detection. The maximum effective accuracy obtained
when expanding the detected space to a neighborhood space
was 86.9%. The detected accuracy improved that the light
sensors were placed near a corner of the room. The positional
arrangement of the light sensors, therefore, should be
optimized. Building the database more or less affected
the accuracy as well. Once the database is built, the
calculation should take little time. This method should
thus be useful for quickly identifying fault points in
gas-insulated switchgears.
KEYWORDS: gas-insulated switchgears, partial discharge,
fault setection, illuminance distribution, database, detective |
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On Modeling of the Luminance Distribution
of the 3D?EObject Surface by the Specular Reflection Component
and Shape Measurement
Naotaka IKEMOTO, Kenji FUJINAMI and Minoru ISOMURA
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A method is described for reducing the large error that
often occurs in the measurement of three-dimensional (3D)
objects using the photometric stereo method when there
is a specular component in the reflection characteristics
of the object's surface.
First, the change in the luminance distribution caused
by the component is estimated based on the correlation
between the modeled distribution and a gray-level image
of the object, created by numerical experiment.
Next, the shape measurement of the hemisphere object was
carried out. Numerical experiment of a hemispherical object
showed that the mean error of normal vector can be reduced
by as much as 90%. This method is applicable to machine
vision, automatic manufacturing, and other industrial
processes.
KEYWORDS: luminance distribution model, specular reflection
component, 3-D shape measurement, gray-level image |
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Experimental Consideration on Scaled-up
Culture Vessels for Pavlova lutheri for Feed Using Artificial
Light Sources
Kanji NAKAJIMA and Hiroya OKUMURA
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The cell density of Pavlova lutheri was measured during
a 17 days-long culture period at the three different-sized
culture vessels; a 3 flask a 20 tank, and a 100 tank.
PPFD (Photosynthetical Photon Flux Density) at the center
of the 3 flask and the 20 tank under fluoresent lamps
was 45ƒÊmol?Em-2?Es-1,
while that at the 100 ? tank was 300ƒÊmol¥m-2?Es-1
under high pressure sodium lamps, and 0?]1300ƒÊmol?Em-2?Es-1
under the natural sun light. The cell density was
2.1x10-7 cells?Em-1
at the 3 flask, 7.4x10-7 cells?Em-1
at the 20 tank, and 1.6x10-7 cells?Em-1
at the 100 tank. Differences at the cell density
were found in between the 3 flask and the 20 tank, though
the same light sources were used for these two systems.
The cell densities at the 100 tank were also different
when high pressure sodium lamps and natural sun light
were used, however no difference at the cell density was
found between the 100 tank under high pressure sodium
lamps and the 3 flask under fluorescent lamps. Through
these results, it can be concluded that a propagation
rate of P.lutheri increases under higher PPFD. For higher
scaling up of vessels will increase under higher PPFD
lighting. It is necessary to examine the much more efficient
lighting in order to maximize a propagation rate of the
micro algae.
KEYWORDS: fluorescent lamp, high pressure sodium lamp,
micro algae, Pavlova lutheri, scaled-up Culture Vessel |
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Statistical Analysis of Traffic Accident
Rate at Dusk
Kazumoto MORITA
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At dusk the change in brightness of peripheral vision
is striking. Such a sudden change in the viewing environment
could affect the vision of a driver, possibly leading
to an accident. I investigated the occurrence of traffic
accidents at dusk by statistical analysis to determine
whether changes in the viewing environment at dusk affect
the accident rate. Dusk is considered to be the time of
civil twilight, which is about 30 minutes in Tokyo. The
analysis was done under certain conditions; for example,
the target area was limited so that the time period for
dusk was basically the same. Furthermore, the effect of
the day of the week on the occurrence rate was investigated.
I found no tendency for traffic accidents to occur with
higher frequency at dusk Moreover, the analysis of the
accident rate of the day of the week showed that the accident
rate is rather related to the traffic volume.
KEYWORDS: traffic accident, dusk, driver, vision, satistical
analysis |
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Theoretical Effect of SnI2 Dosing on Lifetime
of Inductively Coupled Electrodess Metal Halide Lamps
Akira ITOH, Kozo UEMURA, Tsoshihiko ISHIGAMI, Akihiro INOUYE
and Seishi SEKINE
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In an inductively coupled electrodeless metal halide
lamp dosed with NaI and ScI2 dosing a small amount of
Sn I2 into its arc tube suppresses the free I2 gas generation,
which extends the life of the lamp. The free I2 gas is
thought to be left over as a result of Na and Sc loss
reaction with the quartz. It is assumed the Na loss is
caused by its migration into the quartz and that the Sc
loss is caused by the reaction between the quartz and
Sc clusters on the quartz. The Na loss rate depends on
the partial pressure of the Na and the Sc loss rate depends
on the nucleation rate of the Sc clusters, which can be
derived from the nucleation theory of clusters. Thermodynamical
calculations showed that the Na and Sc partial pressures
become 1/100-1/10000 and the nucleation rate of the Sc
clusters becomes negligible with Sn I2 dosing. The rate
of the free I2 gas generation was calculated, assuming
it is proportional to the Na pressure and the Sc cluster
nucleation rate. The proportional coefficients were determined
from the results of lifetime tests and furnace-heating
tests. The calculations showed that the Sn I2 dose sharply
reduces the rate of free I2 gas generation making the
lamp-life longer.
KEYWORDS: inductively coupled electrodeless HID lamp,
free iodine, migration, mucleation, cluster |
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A Technigue for Quantitatively Examining
of Luminance Contrast in the Lighting Environment
Yoshiki NAKAMURA
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Although it is highly desirable to be able to examine
the contrast of luminance quantitatively in order to design
an appropriate brightness pattern, conventional luminance
contrast expressing methods can not be applied to the
actual complicated luminance distribution. A previously
proposed analysis method for expressing the luminance
distribution was used to develop a technique for quantifying
the contrast of luminance in an actual complicated luminance
distribution. Application of this technique showed that
it works well to actual distributions.
KEYWORDS: contrast, luminance contrast, lighting environment,
quantitative representation, filtering |
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