8,455 research outputs found
Mechanical strain isolator mount
Certain devices such as optical instruments must preserve their alignmental integrity while being subjected to mechanical strain. A mechanical strain isolator mount is provided to preserve the alignmental integrity of an alignment sensitive instrument. An alignment sensitive instrument is mounted on a rectangular base. Flexural legs are connected at their proximal ends to the rectangular base. Flexural legs are also spaced parallel to the sides. Mounting pads are connected to the legs at the distal end and the mechanical strain isolator mount is attached to the substrate by means of threaded bolts. When a mounting pad and its respective leg is subjected to lateral strain in either the X or Y direction via the substrate, the respective leg relieves the strain by bending in the direction of the strain. An axial strain on a mounting pad in the Z direction is relieved by a rotational motion of the legs in the direction of the strain. When the substrate is stress free, the flexural legs return to their original condition and thus preserve the original alignment integrity of the alignment sensitive instrument
The effect of ambient temperature on cold start urban traffic emissions for a real world SI car
The influence of ambient temperature on exhaust
emissions for an instrumented Euro 1 SI car was
determined. A real world test cycle was used, based on
an urban drive cycle that was similar to the ECE urban
drive cycle. It was based on four laps of a street circuit
and an emissions sample bag was taken for each lap.
The bag for the first lap was for the cold start emissions.
An in-vehicle direct exhaust dual bag sampling
technique was used to simultaneously collect exhaust
samples upstream and downstream of the three-way
catalyst (TWC). The cold start tests were conducted
over a year, with ambient temperatures ranging from –
2°C to 32°C. The exhaust system was instrumented with
thermocouples so that the catalyst light off temperature
could be determined. The results showed that CO
emissions for the cold start were reduced by a factor of
8 downstream of catalyst when ambient temperature
rose from -2°C to 32°C, the corresponding hydrocarbon
emissions were reduced by a factor of 4. There was no
clear relationship between NOx emissions and ambient
temperature. For subsequent laps of the test circuit the
reduction of CO and HC emissions as a function of
ambient temperature was lower. The time for catalyst
light off increased by 50% as the ambient temperature
was reduced. The results show that the vehicle used is
unlikely to meet the new – 7oC cold start CO emission
regulations
Short-Run Economic Impacts of Hurricane Katrina (and Rita)
Sturm; Erdölförderung; Offshore-Industrie; Makroökonomischer Einfluss; USA
P18. Backstroke Start Performance: The Impact of Using the Omega Backstroke Ledge
Background: FINA recently approved use of the “backstroke ledge” (Omega OBL2) to improve backstroke start performance in competition, but its performance has not been thoroughly evaluated. The purpose of this study was to compare starts performed on a flat wall to those performed with the OBL2, and to identify factors that contribute to better start performance. Methods: Ten elite backstroke swimmers performed three flat-wall and three OBL2 starts. Horizontal impulse, vertical impulse, takeoff velocity and takeoff angle were calculated from the force plate data. Entry distance, time to 10 m and start of hip and knee extension were recorded using digital video cameras. Results: We determined that starts performed with the OBL2 had a faster time to 10 m, less variability in vertical impulse and greater entry distance. Time to 10 m and head entry distance had a significant negative correlation. Starts with the OBL2 also had a trend toward lower resultant takeoff velocity, lower horizontal impulse and greater COM takeoff angle. Discussion and Conclusions: The OBL2 appears to provide a performance advantage by allowing an increased head entry distance, rather than larger impulse on the wall. Additional studies are needed to evaluate the factors that contribute to improved performance when using the OBL2. Coaches may consider head entry distance as a training target. Athletes should use the OBL2 in training and competition to ensure optimal start performance. Interdisciplinary Reflection: Concepts from physical and biological sciences are combined to explain the factors which affect backstroke start performance
Application of a portable FTIR for measuring on-road emissions
The objective of this work was the development of an onroad
in-vehicle emissions measurement technique
utilizing a relatively new, commercial, portable Fourier
Transform Infra-Red (FTIR) Spectrometer capable of
identifying and measuring (at approximately 3 second
intervals) up to 51 different compounds. The FTIR was
installed in a medium class EURO1 spark ignition
passenger vehicle in order to measure on-road
emissions. The vehicle was also instrumented to allow
the logging of engine speed, road speed, global position,
throttle position, air-fuel ratio, air flow and fuel flow in
addition to engine, exhaust and catalyst temperatures.
This instrumentation allowed the calculation of massbased
emissions from the volume-based concentrations
measured by the FTIR. To validate the FTIR data, the
instrument was used to measure emissions from an
engine subjected to a real-world drive cycle using an AC
dynamometer. Standard analyzers were operated
simultaneously for comparison with the FTIR and the
standard analyzer results showed that most pollutants
(NOx, CO2, CO) were within ~10% of a standard analyzer
during steady state conditions and within 20% during
transients. The exception to this was total HC which was
generally 50% or less than actual total HC, but this was
due to the limited number of hydrocarbons measured by
the FTIR. In addition to the regulated emissions, five
toxic hydrocarbon species were analyzed and found to
be sensitive to cold starts in varying proportions. Finally,
FTIR data was compared to results from a commercially
available on-road measurement system (Horiba OBS-
1000), and there was good agreement
Dynamic plantar loading index detects altered foot function in individuals with rheumatoid arthritis but not changes due to orthotic use
Background Altered foot function is common in individuals with rheumatoid arthritis. Plantar pressure distributions during gait are regularly assessed in this patient group; however, the association between frequently reported magnitude-based pressure variables and clinical outcomes has not been clearly established. Recently, a novel approach to the analysis of plantar pressure distributions throughout stance phase, the dynamic plantar loading index, has been proposed. This study aimed to assess the utility of this index for measuring foot function in individuals with rheumatoid arthritis.Methods Barefoot plantar pressures during gait were measured in 63 patients with rheumatoid arthritis and 51 matched controls. Additionally, 15 individuals with rheumatoid arthritis had in-shoe plantar pressures measured whilst walking in standardized footwear for two conditions: shoes-only; and shoes with prescribed custom foot orthoses. The dynamic plantar loading index was determined for all participants and conditions. Patient and control groups were compared for significant differences as were the shod and orthosis conditions.Findings The patient group was found to have a mean index of 0.19, significantly lower than the control group's index of 0.32 (p > 0.001, 95% CI [0.054, 0.197]). No significant differences were found between the shoe-only and shoe plus orthosis conditions. The loading index was found to correlate with clinical measures of structural deformity.Interpretation The dynamic plantar loading index may be a useful tool for researchers and clinicians looking to objectively assess dynamic foot function in patients with rheumatoid arthritis; however, it may be unresponsive to changes caused by orthotic interventions in this patient group.</p
Line Strengths of Rovibrational and Rotational Transitions in the X Ground State of OH
A new line list including positions and absolute intensities (in the form of
Einstein values and oscillator strengths) has been produced for the OH
ground X\DP\ state rovibrational (Meinel system) and pure rotational
transitions. All possible transitions are included with v\primed and
v\Dprimed up to 13, and up to between 9.5 and 59.5, depending on the
band. An updated fit to determine molecular constants has been performed, which
includes some new rotational data and a simultaneous fitting of all molecular
constants. The absolute line intensities are based on a new dipole moment
function, which is a combination of two high level ab initio calculations. The
calculations show good agreement with an experimental v=1 lifetime,
experimental values, and v=2 line intensity ratios
from an observed spectrum. To achieve this good agreement, an alteration in the
method of converting matrix elements from Hund's case (b) to (a) was made.
Partitions sums have been calculated using the new energy levels, for the
temperature range 5-6000 K, which extends the previously available (in HITRAN)
70-3000 K range. The resulting absolute intensities have been used to calculate
O abundances in the Sun, Arcturus, and two red giants in the Galactic open and
globular clusters M67 and M71. Literature data based mainly on [O I] lines are
available for the Sun and Arcturus, and excellent agreement is found.Comment: 17 pages, 8 figues. 7 supplementary files: dipole moment functions
(OH-X-DMFs.txt), equilibrium constants (OH-X-Equilibrium_Constants.txt),
partition function (OH-X-Q_5-6000K.dat), PGOPHER file with molecular
constants and transition matric elements (OH-XX.pgo), vibrational Einstein A
and f values (OH-XX-Avv_fvv.txt), line list (OH-XX-Line_list.txt), and
OH-Transformation_Equation_Extra.doc
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