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Fuel costs are a significant portion of transit agency budgets. Hybrid technology offers an attractive option and has the potential to significantly reduce operating costs for agencies. The main impetus behind use of hybrid transit vehicles is fuel savings and reduced emissions. Laboratory tests have indicated that hybrid transit buses can have significantly higher fuel economy and lower emissions compared to conventional transit buses. However, the number of studies is limited and laboratory tests may not represent actual driving conditions since in-use vehicle operation differs from laboratory test cycles. Several initial studies have suggested that the fuel economy savings reported in laboratory tests may not be realized on-road. The objective of the project described in this paper was to evaluate the in-use fuel economy differences between hybrid-electric and conventional transit buses for the Ames, Iowa (USA) transit authority. On-road fuel economy was evaluated over a 12-month period for 12 hybrid and 7 control transit buses. Fuel economy comparisons were also provided for several older in-use bus types. Buses other than the control and hybrid buses were grouped by model year corresponding to US diesel emission standards. Average fuel economy in miles per gallon was calculated for each bus group overall and by season. Hybrid buses had the highest fuel economy for all time periods for all bus types. Hybrid buses had a fuel economy that was 11.8% higher than control buses overall and was 12.2% higher than buses with model years 2007 and higher, 23.4% higher than model years 2004 to 2006, 10.2% higher than model years 1998 to 2003, 38.1% higher than for model years 1994 to 1997, 36.8% higher for model years 1991 to 1993, and 36.8% higher for model years pre-1991. Differences between groups of buses also varied by season of the year.
Continuous measurement of blood pressure based on pulse
transit time (PTT) using GMR sensors is the state-of-art non-invasive cuffless
method in which modulated magnetic signature of blood (MMSB) is used. In this
paper, the mechanism of MMSB is investigated. According to the experimental
results, it is found that both blood pulse flowing through the applied magnetic
field and the displacement of the GMR sensor caused by blood pulse contribute
to the disturbance of magnetic field detected by GMR sensors. The feasibility
of MMSB method is discussed as well.
A 39-year-old male was admitted
for recurrent ischemic strokes. TEE was performed to detect the potential
intra-cardiac thrombi and right-to-left shunts. A large hypermobile, echodense,
irregular mass was found in the right atrium, which looked like a cluster of
grapes. The motion of the components of the mass was synchronized, prolapsing
into right ventricle in an octopus-like fashion during diastole. There was no
evidence for PFO or other intra-cardiac shunts by color flow Doppler. The
patient was referred to surgery and a continuous 30 cm long thrombus spanning
from the inferior vena cava to the right ventricle was discovered.
The 21st century promises some dramatic changes—some expected, others surprising. One of the more surprising changes is the dramatic peaking in car use and an associated increase in the world’s urban rail systems. This paper sets out what is happening with the growth of rail, especially in the traditional car dependent cities of the US and Australia, and why this is happening, particularly its relationship to car use declines. It provides new data on the plateau in the speed of urban car transportation that supports rail’s increasing role compared to cars in cities everywhere, as well as other structural, economic and cultural changes that indicate a move away from car dependent urbanism. The paper suggests that the rise of urban rail is a contributing factor in peak car use through the relative reduction in speed of traffic compared to transit, especially rail, as well as the growing value of dense, knowledge-based centers that depend on rail access for their viability and cultural attraction. Finally, the paper suggests what can be done to make rail work better based on some best practice trends in large cities and small car dependent cities.