589 research outputs found

    An Analysis of Travelerā€™s Evaluation Frame Toward Public Transport Focusing on Dynamic Nature of Reference Point

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    The internal reference point of travelerā€™s decision-making is dynamic in nature. Public transport ridership considers a decision based on the utility value of gains and losses which can be modeled by using mental accounting theory. This study aims to analyze the dynamic of internal reference points for public transport ridership after implementing transport policies. It describes the decision of travelersā€™ behavior when facing the dynamic value of the utility, whether it is increasing, decreases or stable. This study developed a travelersā€™ behavior model based on mental accounting theory. The result showed that the public transport ridershipā€™s are more likely to change their reference point when realizing gains than losses for transport policies. Furthermore, the way of public transport ridership combines the decrease and increase of the utility value showed that travelers tend to consider which gains and losses occurred simultaneously. Therefore, the integration outcome is more desirable than segregation outcomes, and revealed that mental accounting theory plays a major role in public transport ridership. This survey was conducted for the short-term distance trip, particularly in shopping trip from the residential area (origin) to Community Business District (destination) in Matsuyama city, Japan

    DESIGN OF A CENTRIFUGAL COMPRESSOR FOR NATURAL GAS

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    This work presents the design of a centrifugal compressor for natural gas in three steps. The first step is the 1-D preliminary design heavily based on empirical data, only the design point was considered here. The second step is the flow analysis in the meridional plane. The last step is the CFD analysis to verify if the 1-D design methodology is adequate. The CFD simulations showed good agreement with the results obtained in the preliminary design, proving the importance of empirical data in the design of centrifugal compressors

    Comparative Study of Density over Time by Several Approaches Using Individual and Sample Data in the Mixed Traffic

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    At the macroscopic perspective, traffic analysis requires the knowledge of Fundamental Diagram, which involves the relationship between the variables of density, flow, and speed. As one of the macroscopic traffic flow variables, density can be derived by several approaches. At first, the density of traffic was measured over space, which difficult to be collected mainly in the long section of the road. Therefore, the density variable was simply derived from the fundamental relation of macroscopic traffic flow variable. By this method, the individual speed and flow variable are required in the local measurement. Both traffic density and flow will apply the concept of PCU, which refers to the Indonesian Highway Capacity Manual, 1997 to consider the different characteristic of the vehicle. In the mixed traffic of developing countries, providing traffic data was difficult due to the limitation of the traffic sensor infrastructures. Frequently, providing density variable relies on the sample data for speed analysis. In the present study, the estimation of density will focus on the local measurement over a time interval. By using individual data, density is proposed to be measured directly over time, in which the equation can be modified to utilize the sample data. The number of sample for speed analysis will be varied to know the accuracy and the performance of each approach in the density estimation of mixed traffic. Several approaches for density estimation will be summarized and compared each other. Theoretically, the estimated density which measured over time and space by using individual data can provide the most appropriate result. So, this estimated density will be established as an actual density throughout the study. Then, the performance of each approach either using individual or sample data will be evaluated upon the actual traffic density by mean absolute percentage error (MAPE). The result shows by using the same trap length to measure the speed, the existing and the proposed approaches provide a good estimation of density either by utilizing individual data or sample data of the vehicle speed. This result was indicated by the MAPE value, which obtained under ten percent. Based on the further evaluation of the MAPE value, the performance of each approach was changed by utilizing the different category of data. In addition, estimation of traffic density which utilizes the sample data of vehicle speed has good reliability

    An investigation of the distribution of gaze estimation errors in head mounted gaze trackers using polynomial functions

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    Second order polynomials are commonly used for estimating the point-of-gaze in head-mounted eye trackers. Studies in remote (desktop) eye trackers show that although some non-standard 3rd order polynomial models could provide better accuracy, high-order polynomials do not necessarily provide better results. Different than remote setups though, where gaze is estimated over a relatively narrow field-of-view surface (e.g. less than 30x20 degrees on typical computer displays), head-mounted gaze trackers (HMGT) are often desired to cover a relatively wider field-of-view to make sure that the gaze is detected in the scene image even for extreme eye angles. In this paper we investigate the behavior of the gaze estimation error distribution throughout the image of the scene camera when using polynomial functions. Using simulated scenarios, we describe effects of four different sources of error: interpolation, extrapolation, parallax, and radial distortion. We show that the use of third order polynomials result in more accurate gaze estimates in HMGT, and that the use of wide angle lenses might be beneficial in terms of error reduction

    Triphenyltin and intra-axonal Ca2+ mobilization

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    Triphenyltin (TPT) is an organotin compound causing environmental hazard to many wild creatures. Our previous findings show that TPT increases of the frequency of spontaneous glycinergic inhibitory postsynaptic currents (sIPSCs) in rat spinal neurons without changing the amplitude and 1/e decay time. In our study, the effects of 2-aminoethoxydiphenyl borate (2-APB), dantrolene sodium, and thapsigargin on sIPSC frequency were examined to reveal the contribution of intra-axonal Ca2+ mobilization by adding TPT. 2-APB considerably attenuated the TPT-induced facilitation of sIPSC frequency while dantrolene almost completely masked the TPT effects, suggesting that the TPT-induced synaptic facilitation results from the activation of both IP3 and ryanodine receptors on endoplasmic reticulum (ER) membrane, though inositol triphosphate (IP3) receptor is less sensitive to TPT. Thapsigargin itself significantly increased the sIPSC frequency without affecting the current amplitude and decay time. Successive addition of TPT could not further increase the sIPSC frequency in the presence of thapsigargin, indicating that thapsigargin completely masked the facilitatory action of TPT. Results suggest that TPT activates the IP3 and ryanodine receptors while TPT inhibits the Ca2+-pump of ER membranes, resulting in the elevation of intra-axonal Ca2+ levels, leading to the increase of spontaneous glycine release from synaptic vesicles

    Passenger transmission and productiveness of transit lines with high loads

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    Deterministic transit capacity analysis applies to planning, design and operational management of urban transit systems. The Transit Capacity and Quality of Service Manual (1) and Vuchic (2, 3) enable transit performance to be quantified and assessed using transit capacity and productive capacity. This paper further defines important productive performance measures of an individual transit service and transit line. Transit work (p-km) captures the transit task performed over distance. Passenger transmission (p-km/h) captures the passenger task delivered by service at speed. Transit productiveness (p-km/h) captures transit work performed over time. These measures are useful to operators in understanding their servicesā€™ or systemsā€™ capabilities and passenger quality of service. This paper accounts for variability in utilized demand by passengers along a line and high passenger load conditions where passenger pass-up delay occurs. A hypothetical case study of an individual bus serviceā€™s operation demonstrates the usefulness of passenger transmission in comparing existing and growth scenarios. A hypothetical case study of a bus lineā€™s operation during a peak hour window demonstrates the theoryā€™s usefulness in examining the contribution of individual services to line productive performance. Scenarios may be assessed using this theory to benchmark or compare lines and segments, conditions, or consider improvements
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