Abstract: The nonlinear damping behavior is usually ignored in
the design of a miniature moving-coil loudspeaker. But when the
loudspeaker operated in air, the damping parameter varies with the
voice-coil displacement corresponding due to viscous air flow. The
present paper presents an identification model as inverse problem to
identify the nonlinear damping parameter in the lumped parameter
model for the loudspeaker. Theoretical results for the nonlinear
damping are verified by using laser displacement measurement
scanner. These results indicate that the damping parameter has the
greatly different nonlinearity between in air and vacuum. It is believed
that the results of the present work can be applied in diagnosis and
sound quality improvement of a miniature loudspeaker.
Abstract: Using of natural lighting has come into prominence in
constructed buildings, especially in last ten years, under scope of
energy efficiency. Natural lighting methods are one of the methods
that aim to take advantage of day light in maximum level and
decrease using of artificial lighting. Increasing of day light amount in
buildings by using suitable methods will give optimum result in
terms of comfort and energy saving when the daylight-artificial light
integration is ensured with a suitable control system. Using of natural
light in places that require lighting will ensure energy saving in great
extent. With this study, it is aimed to save energy used for purpose of
lighting. Under this scope, lighting of a scanning laboratory of a
hospital was realized by using a lighting automation containing
natural and artificial lighting. In natural lighting, light pipes were
used and in artificial lighting, dimmable power LED modules were
used. Necessity of lighting was followed with motion sensors. The
lighting automation containing natural and artificial light was ensured
with fuzzy logic control. At the scanning laboratory where this
application was realized, energy saving in lighting was obtained.
Abstract: Worldwide many electrical equipment insulation
failures have been reported caused by switching operations, while
those equipments had previously passed all the standard tests and
complied with all quality requirements. The problem is mostly
associated with high-frequency overvoltages generated during
opening or closing of a switching device. The transients generated
during switching operations in a Gas Insulated Substation (GIS) are
associated with high frequency components in the order of few tens
of MHz.
The frequency spectrum of the VFTO generated in the 220/66 kV
Wadi-Hoff GIS is analyzed using Fast Fourier Transform technique.
The main frequency with high voltage amplitude due to the operation
of disconnector (DS5) is 5 to 10 MHz, with the highest amplitude at 9
MHz. The main frequency with high voltage amplitude due to the
operation of circuit breaker (CB5) is 1 to 25 MHz, with the highest
amplitude at 2 MHz.
Mitigating techniques damped the oscillating frequencies
effectively. The using of cable terminal reduced the frequency
oscillation effectively than that of OHTL terminal. The using of a
shunt capacitance results in vanishing the high frequency
components. Ferrite rings reduces the high frequency components
effectively especially in the range 2 to 7 MHz. The using of RC and
RL filters results in vanishing the high frequency components.
Abstract: In this paper, we propose a hardware and software
design method for automotive Electronic Control Units (ECU)
considering the functional safety. The proposed ECU is considered for
the application to Electro-Mechanical Actuator systems and the
validity of the design method is shown by the application to the
Electro-Mechanical Brake (EMB) control system which is used as a
brake actuator in Brake-By-Wire (BBW) systems. The importance of a
functional safety-based design approach to EMB ECU design has been
emphasized because of its safety-critical functions, which are executed
with the aid of many electric actuators, sensors, and application
software. Based on hazard analysis and risk assessment according to
ISO26262, the EMB system should be ASIL-D-compliant, the highest
ASIL level. To this end, an external signature watchdog and an
Infineon 32-bit microcontroller TriCore are used to reduce risks
considering common-cause hardware failure. Moreover, a software
design method is introduced for implementing functional
safety-oriented monitoring functions based on an asymmetric dual
core architecture considering redundancy and diversity. The validity
of the proposed ECU design approach is verified by using the EMB
Hardware-In-the-Loop (HILS) system, which consists of the EMB
assembly, actuator ECU, a host PC, and a few debugging devices.
Furthermore, it is shown that the existing sensor fault tolerant control
system can be used more effectively for mitigating the effects of
hardware and software faults by applying the proposed ECU design
method.
Abstract: A gold coated copper rotating electrode was used to
eliminate surface oxidation effect. This study examined the effect of
electrode rotation on the ozone generation process and showed that an
ozonizer with an electrode rotating system might be a possible way to
increase ozone-synthesis efficiency. Two new phenomena appeared
during experiments with the rotating electrode. First was that ozone
concentration increased to about two times higher than that of the case
with no rotation. Second, input power and discharge area were found
to increase with the rotation speed. Both ozone concentration and
ozone production efficiency improved in the case of rotating electrode
compared to the case with a non-rotating electrode. One possible
reason for this was the increase in discharge length of
micro-discharges during electrode rotation. The rotating electrode
decreased onset voltage, while reactor capacitance increased with
rotation. Use of a rotating-type electrode allowed earlier observation
of the ozone zero phenomena compared with a non-rotating electrode
because, during rotation, the entire electrode surface was functional,
allowing nitrogen on the electrode surface to be evenly consumed.
Nitrogen demand increased with increasing rotation s
Abstract: A new technique to quantify the differential mode
delay (DMD) in multimode fiber (MMF) is been presented. The
technique measures DMD based on angular launch and
measurements of the difference in modal delay using variable
apertures at the fiber face. The result of the angular spatial filtering
revealed less excitation of higher order modes when the laser beam is
filtered at higher angles. This result would indicate that DMD
profiles would experience a data pattern dependency.
Abstract: High-voltage power transmission lines are the back
bone of electrical power utilities. The stability and continuous
monitoring of this critical infrastructure is pivotal. Nine-Sigma
representing Eskom Holding SOC limited, South Africa has a major
problem on proactive detection of fallen power lines and real time
sagging measurement together with slipping of such conductors. The
main objective of this research is to innovate RFID technology to
solve this challenge. Various options and technologies such as GPS,
PLC, image processing, MR sensors and etc., have been reviewed
and draw backs were made. The potential of RFID to give precision
measurement will be observed and presented. The future research
will look at magnetic and electrical interference as well as corona
effect on the technology.
Abstract: Modern Society is strongly dependent on a reliable
power supply. The availability of cheap and reliable supply of
electrical energy is an indicator of societal welfare. Uninterrupted
reliable operation of a modern power system depends to a great
extent on reliable and satisfactory performance of insulators under
different environmental conditions. This paper reports result of
natural pollution tests that have been done at sites around city of
Aligarh (India). Flashover voltage per insulation distance (FOVUID)
of porcelain disc insulator for different pH values, ESDD has been
recorded for proper correlation between electrical and chemical
parameters. The pH of the contaminants has been suggested to be an
effective pollution severity indicator and may be used as a diagnostic
parameter for proper maintenance of porcelain insulators.