2,160 research outputs found
Research and Technology
Langley Research Center is engaged in the basic an applied research necessary for the advancement of aeronautics and space flight, generating advanced concepts for the accomplishment of related national goals, and provding research advice, technological support, and assistance to other NASA installations, other government agencies, and industry. Highlights of major accomplishments and applications are presented
Design and numerical simulation of the real-time particle charge and size analyser
The electrostatic charge and size distribution of aerosol particles play a very
important role in many industrial applications. Due to the complexity and the
probabilistic nature of the different charging mechanisms often acting simultaneously, it
is difficult to theoretically predict the charge distribution of aerosol particles or even
estimate the relative effect of the different mechanisms. Therefore, it is necessary to
measure the size and also the bipolar charge distribution on aerosol particles.
The main aim of this research project was to design, implement and simulate a
signal processing system for novel, fully functional measurement instrument capable of
simultaneously measuring in real time the bipolar charge and size distribution of medical
aerosols. The Particle Size and Charge Analyser (PSCA), investigated in this thesis, uses
Phase Doppler Anemometry (PDA) technique. The PDA system was used to track the
motion of charged particles in the presence of an electric field. By solving the equation of
particle motion in a viscous medium combined with the simultaneous measurement of its
size and velocity, the magnitude as well as the polarity of the particle charge can be
obtained. Different signal processing systems in different excitation fields have been designed and implemented. These systems include: velocity estimation system using
spectral analysis in DC excitation field, velocity estimation system based on Phase Locked
Loop (PLL) technique working in DC as well as sine-wave excitation fields, velocity
estimation system based on Quadrature Demodulation (QD) technique under sine-wave
excitation method, velocity estimation system using spectral analysis in square-wave
excitation field and phase shift estimation based on Hilbert transformation and correlation
technique in both sine-wave and square-wave excitation fields. The performances of these
systems were evaluated using Monte Carlo (MC) simulations obtained from the
synthesized Doppler burst signals generated from the mathematical models implemented
in MATLAB. The synthesized Doppler Burst Signal (DBS) was subsequently corrupted
with the added Gaussian noise. Cross validation of the results was performed using
hardware signal processing system employing Arbitrary Waveform Generator and also
NASA simulator to further confirm the validity of the estimation
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Investigation of bipolar charge distribution of pharmaceutical dry powder aerosols using the phase doppler anemometry system
This thesis was submitted for the award of Doctor of Philosophy and was awarded by Brunel University London.Electrostatic properties of formulation component materials and blends play an
important role in dry powder inhalation (DPI) products, and that valid measurement of charge
distribution will lead to more precise control of powder behavior in DPI manufacturing
processes. Ultra-fine powders are known to be bipolarly charged, have non-spherical shapes
and tend to be highly cohesive. Real time, non-invasive techniques need to be developed to
obtain a precise and accurate time-history characteristic of electrically charged powders as
they aerosolize from a DPI product, and how this measure relates to materials behavior
throughout the various steps of a manufacturing process i.e. from drug micronisation,
blending with lactose, through to filling dose units. A novel non-invasive technique for
simultaneous measurement of size and charge of pharmaceutical powders is considered
which employs the Phase Doppler Anemometry (PDA) system. Previous research
demonstrated the advantages of this technique in measuring the bipolar charge distribution on
a population of particles. These findings led to significant improvements in understanding
performance of dry powder formulations, manufacturing processes and development of new
platforms for inhaled drug delivery. The main aim of this research is to perform an investigation of electrostatic propertiesof pharmaceutical dry aerosols using the PDA system. The PDA technique was used to track
the motion of charged particles in the presence of an electric field. The magnitude as well as
the polarity of the particle charge can be obtained by solving the equation of particle motion
in DC and AC fields combined with the simultaneous measurement of its size and velocity.
The results show the capability of the technique to allow real-time size and charge
distribution in the control of dry powder attributes that are critical to fully understanding
manufacturing design space. The data obtained from initial investigations of electrical properties of pharmaceutical powders and bipolar charge measurements was used to perform an in-depth study of
electrostatic properties of pharmaceutical aerosols dispensed by dry powder inhaler (DPI)
devices. The delivery of a drug to the lungs can only be achieved by a combination of inhaler
device and drug formulation which is capable of producing an aerosol of an aerodynamic
diameter smaller than 5 ÎĽm and of appropriate charge. The aerosols generated by these
devices are often bipolarly charged and can influence specific site deposition in human lung.
By controlling the electrostatic charge generated by tribielectrification, it may be possible to
achieve the desired drug deposition in the airways. Bipolary charged dispensed ultrafine
particles are inhaled through the extrathoracic and tracheobronchial airways down into the
alveolar region. Anatomically realistic respiratory airways and computation fluid dynamics
(CFD) models have been created to study airflow structures and predict aerosol deposition
within the human respiratory system using visible human data sets, human casts and
morphometric data. Many theoretical studies of charged aerosol deposition in human
respiratory systems have been developed, however getting real time, non-intrusive data of
bipolar charge levels on aerosols dispensed from DPI’s within the human respiratory system
represents a challenging issue. This research project presents a simplified human upper airway model which
combined with the modified Phase Doppler Anemometry (PDA) system is able to provide
real time bipolar charge distributions of aerosols delivered from several commercially
available DPI devices. A three dimensional (3D) reconstruction of the upper respiratory
system was performed from two dimensional (2D) images obtained from computerized
tomography (CT), magnetic resonance imaging (MRI) and cryosectioned images available
from Visible Human Server data set (Ecole Polytechnique Fédérale de Lausanne). The
resulting dimensions of the model were consistent with morphometric data from the literature
from which the simplified upper airway model consisting of two connected segments, i.e., the
oral airways from the mouth to trachea (Generation G0), was created. The findings of this
study provided a better understanding of the interaction between specific active ingredients
and DPI devices. These results may be used in designing future generation DPI devices and a
better understanding of aerosol transport and deposition efficiency within the human airways.Engineering and Physical Sciences Research Council. Pfizer team, U
Air pollution monitoring instrumentation A survey
Air pollution monitoring instrumentation developed for aerospace uses surveyed for industrial application
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