Engine performance and toxic gas analysis of biobutanol-blended gasoline as a vehicle fuel

A comprehensive study evaluating the performance of biobutanol-blended gasoline in passenger cars was conducted because biobutanol is considered a better biofuel than bioethanol as it has no water solubility and it has a higher caloric value, giving it a higher energy value. Several kinds of samples—suboctane gasoline, 8 volume percentage and 16 volume percentage biobutanol—blended gasoline, and a 10 volume percentage MTBE-blended market sample (as the oxygencontaining gasoline)-were tested to evaluate the engine performance in terms of the detergency of the intake valves and combustion chambers, power, emissions, and fuel efficiency. Additionally, the toxicity of the emissions from these biobutanolblended samples was tested in order to assess the viability of biobutanol as one of the competitive potential substitutes for MTBE as an oxygenator in the near future. The results show that biobutanol-blended gasoline samples had relatively better detergency, relatively higher power, and similar levels of emissions compared with those of MTBE-blended gasoline. Formaldehyde was emitted from all of the samples at almost the same levels and within the error range, whereas biobutanolblended gasoline samples emitted approximately three times the amount of acetaldehyde than did the suboctane gasoline. This study shows that biobutanol is one of the best alternative bioalcohol fuels for use in the near future.     

Damper modeling for dynamic simulation of a large bus with MR damper

In this study, a large bus is tested to measure its dynamic response by the single-lane change test and the rapid stop test. A full car model is established by ADAMS/Car for computer simulation. For multibody modeling of a large bus, user-defined templates are used in the simulation. Simulation results of the single-lane change test and the rapid braking test are compared to the results of the physical experiments, in which several sensors are installed to measure the vehicle’s responses. The results obtained from the simulation show good agreement with the tests’ results. A dynamic model for the MR(magnetic-rheological) damper is also developed by employing the Magic Formula model, which is widely used in the nonlinear modeling of a tire. Bump simulation of a full car with the MR damper is carried out to verify the performance of the MR damper. The comparison of the simulation results obtained with the MR damper model to the results obtained with the traditional passive damper model showed improved response of the vehicle with the MR damper.     

Effect of fuel stratification on initial flame development: Part 3-high swirl condition

This paper discusses the final investigation into the effect of fuel stratification on flame propagation. In previous works, the characteristics under the no port-generated swirl condition and the low-swirl condition were considered. For this purpose, the initial flame development and propagation were visualized under different axially stratified states in a modified optical single-cylinder SI engine. The images were captured by an intensified CCD camera through the quartz window mounted in the piston. Stratification was controlled by the combination of the port swirl ratio and injection timing. These were averaged and processed to characterize the flame propagation. The flame stability was estimated by the weighted average of flame area and luminosity. The stability was also evaluated through the standard deviation of flame area and propagation distance and through the mean absolute deviation of the propagation direction. The results show that the LML is expanded remarkably under the high-swirl cases up to the highest relative AFRs of 1.71 and 1.75 between 140 and 160CA. In addition, similar to the low-swirl condition, the flame-flow interaction determines the direction of flame propagation, and the governing roles of the two factors vary according to the swirl level; the flow is more important at the higher swirl conditions, and the flame is more important at the lower swirl condition. Finally, fast and stable flame propagation can be achieved under the preferably stratified condition, which is induced by the suitable combination of the high swirl and injection timing.     

Simulating the impacts of household travel on greenhouse gas emissions,urban air quality,and population exposure

This paper establishes a link between an activity-based model for the Greater Toronto Area (GTA), dynamic traffic assignment, emission modelling, and air quality simulation. This provides agent-based output that allows vehicle emissions to be tracked back to individuals and households who are producing them. In addition, roadway emissions are dispersed and the resulting ambient air concentrations are linked with individual time-activity patterns in order to assess population exposure to air pollution. This framework is applied to evaluate the effects of a range of policy interventions and 2031 scenarios on the generation of vehicle emissions and greenhouse gases in the GTA. Results show that the predicted increase of approximately 2.6 million people and 1.3 million jobs in the region by 2031 compared to 2001 levels poses a major challenge in achieving meaningful reductions in GHGs and air pollution.     

A network option portfolio management framework for adaptive transportation planning

A real option portfolio management framework is proposed to make use of an adaptive network design problem developed using stochastic dynamic programming methodologies. The framework is extended from Smit’s and Trigeorgis’ option portfolio framework to incorporate network synergies. The adaptive planning framework is defined and tested on a case study with time series origin-destination demand data. Historically, OD time series data is costly to obtain, and there has not been much need for it because most transportation models use a single time-invariant estimate based on deterministic forecasting of demand. Despite the high cost and institutional barriers of obtaining abundant OD time series data, we illustrate how having higher fidelity data along with an adaptive planning framework can result in a number of improved management strategies. An insertion heuristic is adopted to run the lower bound adaptive network design problem for a coarse Iran network with 834 nodes, 1121 links, and 10 years of time series data for 71,795 OD pairs.     

西江长洲枢纽库尾段采砂工程对航道通航水流条件的影响

西江航道桂平航运枢纽—长洲水利枢纽之间存在约34 km的水位未衔接段,而大藤峡水利枢纽建设选取的江口料场位于长洲枢纽库区回水末端和上游附近滩段。为研究库尾段采砂工程对上游通航水流条件的影响,须同步考虑上游来水和下游库区回水的变化,建立桂平三江口上游黔江河段16 km和桂平枢纽—长洲枢纽约156 km的长河段二维水流数学模型,分析采砂工程对航道通航水流条件的影响。结果表明,采砂工程实施后上游桂平航运枢纽引航道水位降落0.09 m,布岭沙弯道凸岸侧边滩挖除引起主流一定左偏。整体上,除设计流量外,库尾段采砂工程对航道水流条件影响较小。     

基于纸纤维改性的隧道工程透水砂浆性能研究北大核心CSCD

为提出一种适用于隧道初期支护基面找平并且具有一定透水性能的砂浆,将纸纤维加入砂浆试块中对其性能进行改性。通过分析纸纤维的降解原理,并将不同掺量的纸纤维加入砂浆试块中,对其体积密度、吸水率、抗压强度等基本性能指标及微观结构进行测试和分析。由试验结果可知:在碱性环境中,纸纤维具有可降解的性能特点;纸纤维可以使普通砂浆试块的吸水率提升2~3倍,同时也会造成砂浆试块的体积密度和抗压强度降低;对砂浆试块吸水率和抗压强度进行线性拟合后发现其吸水率和抗压强度呈现负相关关系。研究结果表明,通过纸纤维对砂浆进行透水性能的提升是可行的,但是纸纤维掺量对砂浆其他性能的影响还有待进一步研究。     

Time-variant ultimate longitudinal strength of corroded bulk carriers

Many bulk carrier losses have been reported of late, and one of the possible causes of such casualties is thought to be the structural failure of aging hulls in rough weather. In aging ships, corrosion and fatigue cracks are the two most important factors affecting structural safety and integrity. This paper uses a set of the time-dependent corrosion wastage models for 23 different member locations/categories of bulk carriers previously developed by the authors, based on the available corrosion measurements for existing large bulk carrier structures. Differences due to the location and corrosion severity of every member type are taken into account. The nominal design corrosion values for the primary members are suggested based on the annualized corrosion rates obtained in the present study. The effect of time-variant corrosion wastage on the ultimate hull girder strength as well as the section moduli is studied. The criteria for repair and maintenance of heavily corroded structural members so as to keep the ultimate longitudinal strength at an acceptable level are discussed. Important insights and conclusions developed are summarized.     

Origin–destination synthesis for aviation network data: examining hub operations in the domestic and international US markets

Hub‐and‐spoke networking is a key feature of current aviation markets in which hubs, as connecting points, function to consolidate and redistribute flows. This indicates that observation of traffic on a segment does not necessarily convey information about the origin to destination routing of passenger journeys because of the unavoidable detours in the system. This paper examines the heterogeneity of the flow composition in domestic and international US markets, which in turn allows us to observe the variation of operations across major hubs. A modified Route Flow Estimator for origin–destination synthesis (or origin–destination matrix estimation) is designed to decompose the segment traffic into itinerary‐based passenger trips. Several public and commercial databases, which are easily accessible, are exploited (and reconciled) for the model in order to (i) generate possible trip itineraries using those segment markets, and (ii) link data‐driven operational conditions with the underlying segment flows. The results are validated with US domestic trip observations and empirical knowledge related to the air transportation system. Then, the variability of the hub operations is examined based on sensitivity tests using the model parameters. From the resolution of itinerary‐based estimates, we observe that major airports' hub operations are spatially uneven, particularly with respect to domestic and international connecting passengers. Copyright © 2017 John Wiley & Sons, Ltd.     

就地冷再生技术在高速公路养护工程中的应用研究

就地冷再生技术具有施工便捷、污染小、旧料回收利用率高、节约成本等优势,在公路养护中得到了利用.以S49新扬高速为例,从适用条件、混合料设计、路用性能验证以及社会经济效益等方面,对就地冷再生技术进行系统研究,结果表明就地冷再生技术在高速公路养护工程中应用效果理想,可进行推广运用.