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Search Results: 1 - 10 of 426 matches for " transit. "
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Evaluation of In-Use Fuel Economy for Hybrid and Regular Transit Buses  [PDF]
Shauna L. Hallmark, Bo Wang, Yu Qiu, Robert Sperry
Journal of Transportation Technologies (JTTs) , 2013, DOI: 10.4236/jtts.2013.31006

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.

Developing Innovative Concepts for Measuring and Assessing Transit System Maturity  [PDF]
Khaled Abbas
Journal of Transportation Technologies (JTTs) , 2017, DOI: 10.4236/jtts.2017.72013
Abstract: In this research three new innovative concepts are introduced and developed: the first defined as Transit System Maturity Components (TSMC), the second referred to as Transit System Maturity Scale (TSMS) and the third labeled as Transit System Maturity Index (TSMI). The TSMC is meant to conceptualise the main strategic generic components characterising the maturity of transit systems. The TSMS is an S shaped scaling system for measuring maturity of transit system components. The TSMI presents an innovative index meant to assess the overall level of maturity of a city transit system. Such framework is envisaged to be used to determine and compare the overall maturity levels of transit systems in cities of the world as well as to act as a basis to identify strengths & gaps that need to be addressed/completed. Furthermore, it can also act as an ingredient in shaping and developing future road maps for transit system in cities across the world. The research concludes by demonstrating the applicability of TSMC, TSMS, and TSMI in conducting an initial assessment of the Transit System Maturity for the fast growing city of Dubai.
Transit-Time Flow Measurement: Letter to The Editor  [PDF]
Elsayed Elmistekawy
Open Journal of Thoracic Surgery (OJTS) , 2012, DOI: 10.4236/ojts.2012.22007
Abstract: Transit-time flow technology is considered as a quality of care in bypass surgery especially in off pump revascularization. Transit time flow measurement is a real time, direct, easy and handy tool for assessment quality of anastomosis and graft blood flow.
Mechanism of Cuff-Less Blood Pressure Measurement Using MMSB  [PDF]
Yibin Li, Yangyu Gao, Ning Deng
Engineering (ENG) , 2013, DOI: 10.4236/eng.2013.510B025

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.

Early peak of hydrogen during lactose breath test predicts intestinal motility  [PDF]
Veronica Ojetti, Teresa Antonella Di Rienzo, Giovanna D’Angelo, Emidio Scarpellini, Gianluca Rizzo, Maria Chiara Campanale, Antonio Gasbarrini
Open Journal of Gastroenterology (OJGas) , 2014, DOI: 10.4236/ojgas.2014.41007
Abstract: Lactose breath test (LBT) is considered the gold standard for the diagnosis of lactose malabsorption. The test is considered positive for a peak of hydrogen (H2) 20 parts per million (ppm) above the baseline. Some patients (pts) showed a rapid peak between 30 and 90 minutes after lactose ingestion. The aim of this study was to evaluate the predictive value of an early peak during a LBT and an accelerated oro-cecal transit time (OCTT). We retrospectively analyzed all pts who referred to our Gastroenterology unit for Irritable Bowel Syndrome, from January to September 2012, who performed LBT, glucose and lactulose breath test. We consider a positive LBT for a peak of H2 > 20 ppm, a positive GHBT for a peak >12 ppm and we considered a normal OCCT a peak of H2 ≥ 10 ppm between 75 ± 105 min after lactulose load. The correlation between LBT and OCTT was evaluated by Pearson score. 93 pts (65 F/28 M mean age 47 ± 6 years) with a positive LBT, without small intestinal bacterial overgrowth were analyzed: 46 pts (32 F/14 M; mean age 48 ± 6 years) with an early peak (<90 min) of H2 (≥20 ppm) were enrolled as case, and 47 pts matched for sex and age with a peak of H2 after 90 min were enrolled as controls. 72% (33/46) of the group with an early peak showed an accelerated, 17% (8/46) a normal and 11% (5/46) a delayed OCTT. Meanwhile, in control group 40.4% (19/47) showed a normal, 57.5% (27/47) a delayed and just 1 pts an accelerated OCTT. The specificity and sensibility of LBT for an accelerated OCTT were 97.9% and 71.7% respectively. The positive predictive value of LBT for an accelerated OCTT is 97.1%; the negative predictive value is 78%. There is a significant correlation between LBT and OCTT (p < 0.05). The presence of an early peak of H2 between 30 and 90 min after the ingestion of 25 gr of lactose could predict the presence of an accelerated OCTT in 97% of pts. If confirmed by further study, in this subset of pts, lactulose breath test for evaluating OCTT could be avoided.
A Long Right Atrial Thrombus Intermittently Prolapsing into Right Ventricle in a Patient with Recurrent Ischemic Stroke: An Image Report  [PDF]
Zhigang Liu, Salman M. Malik, James S. Gammie, Boaz D. Rosen
Case Reports in Clinical Medicine (CRCM) , 2014, DOI: 10.4236/crcm.2014.35068

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.

Design of Data Model for Urban Transport GIS  [PDF]
Wen Zeng, Xiao-Jie Chang, Jian-Jun Lv
Journal of Geographic Information System (JGIS) , 2010, DOI: 10.4236/jgis.2010.22016
Abstract: Constructing the data model for public transportation by integrating the spatial and the non-spatial information, is the basis of reasonable plan and effective management of urban public transport. This paper presents a transit data model based on geographic information systems (GIS) technology, which utilizes arc-node networks, and manages the foundational bus data with point, link, polygon and record features. In this model, a transport network is generated and maintained in a dynamic manner, and hence supports planning, construction, management, operation and optimization functions for transit facilities and routes, as well as day-to-day transactions. Public transportation GIS established on this model foundation will remarkably upgrade the construction level and the urban service ability.
Optimisation of a Bus Network Configuration and Frequency Considering the Common Lines Problem  [PDF]
Hiroshi Shimamoto, Jan-Dirk Schm?cker, Fumitaka Kurauchi
Journal of Transportation Technologies (JTTs) , 2012, DOI: 10.4236/jtts.2012.23024
Abstract: Public transportation network reorganisation can be a key measure in designing more efficient networks and increasing the number of passengers. To date, several authors have proposed models for the “transit route network design problem” (TRNDP), and many of them use a transit assignment model as one component. However, not all models have considered the “common lines problem,” which is an essential feature in transit network assignment and is based on the concept that the fastest way to get to a destination is to take the first vehicle arriving among an “attractive” set of lines. Thus, we sought to reveal the features of considering the common lines problem by comparing results with and without considering the problem in a transit assignment model. For comparison, a model similar to a previous one was used, formulated as a bi-level optimisation problem, the upper problem of which is described as a multi-objective problem. As a result, although the solutions with and without considering the common lines showed almost the same Pareto front, we confirmed that a more direct service is provided if the common lines problem is considered whereas a less direct service is provided if it is not. With a small network case study, we found that considering the common lines problem in the TRNDP is important as it allows operators to provide more direct services.
Peak Car Use and the Rise of Global Rail: Why This Is Happening and What It Means for Large and Small Cities  [PDF]
Peter Newman, Jeffrey Kenworthy, Garry Glazebrook
Journal of Transportation Technologies (JTTs) , 2013, DOI: 10.4236/jtts.2013.34029

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.

Heidegger y Vattimo: intérpretes de Nietzsche
Santiesteban, Luis César;
Diánoia , 2009,
Abstract: the present article examines two of the most important twentieth-century interpretations of nietzsche: the exegesis of heidegger, and vattimo's interpretation. in the first part, the process heidegger followed to interpret nietzsche is analyzed. on his interpretation, heidegger portrays nietzsche as the last metaphysician. the article understands this interpretation as suggesting that heidegger used the ideas of nietzsche to secure his own project of overcoming metaphysics. the article thus deals with the themes of nihilism and heidegger's understanding of nietzsche as decision and transit. in the second part, the analysis focuses on vattimo's daring interpretation of nietzsche as a philosopher that surpassed metaphysics. for that purpose he emphasizes nietzsche's nihilism, and urges the man of today to take notice of the message of such an event and to act accordingly.
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