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1.
Yutao Wang Lars Hansson Nan Sha Yanqiang Ding Renqing Wang Jian Liu 《Stochastic Environmental Research and Risk Assessment (SERRA)》2013,27(5):1231-1238
Road transportation has attracted extensive attention throughout the world because of its high energy demands and numerous externalities. Sustainable road transportation has thus become a great challenge for politicians and decision-makers all over the world. There have been a series of studies indicating that appropriate pricing of fuel can be both effective and efficient for reducing overconsumption of transport fuel. However, relatively little research has been done on fuel price approaches in developing country contexts. For a country like China, where road traffic today is growing more than in other countries, there is a strategic interest to do more economic analyses of fair and efficient pricing of fuel. In this study, we present a strategic assessment of fuel pricing in energy conservation and CO2 reduction from road transportation in China, both in a retrospective and a prospective perspective. First of all, the correlation between fuel price and road transport gasoline demand, based upon data from 1995 to 2007, was examined with an econometric model. Secondly, on basis of the elasticity model, the potential reductions with respect to fuel demand and Green House Gas (GHG) emissions as a consequence of a strategic fuel tax implementation in China were examined up to 2030. The results indicate that such strategic fuel taxation can play a considerable role in steering the growth of road transport gasoline demand, and thus also Chinese GHG emissions. 相似文献
2.
自X射线成像技术应用于安检领域行包货物的查验以来,CT成像技术占据越来越重要的角色和地位。传统安检CT应用模式难以满足海关和民航等交通物流枢纽中心行包货物实时验放的应用需求和公共场所疫情防控要求,查得快、验得准、拦得住的CT智能解决方案得以蓬勃发展,有效提高行包货物的查验效率和旅客的通行效率,有力保障国境安全、人身安全和财产安全,具有巨大的发展潜力和广阔的市场前景。 相似文献
3.
The fatigue life of critical members, such as hangers, floor-beams and stringers in a single track, open deck railroad truss bridge, was investigated for various unit freight trains, operating at different speeds. A partial bridge model was used, along with a three-car train, to determine the stress cycles. For determining the fatigue lives of critical members, four fully-loaded trains per day were assumed to pass over the bridge. Each train was assumed to consist of one hundred 70-ton cars or seventy 100-ton cars. The 100-ton freight cars cause large stress ranges, and consequently shorter fatigue lives than the 70-ton freight cars. For the hundred-car train, with 70-ton and 100-ton cars mixed in various proportions, the fatigue lives became shorter as the percentage of 100-ton cars in the consist was increased. The impact percentages were also studied. 相似文献
4.
Sudarmanto Budi Nugroho Akimasa Fujiwara Junyi Zhang 《Stochastic Environmental Research and Risk Assessment (SERRA)》2011,25(5):655-669
A bus rapid transit (BRT) system began operation in Jakarta City, Indonesia, in January 2004 and led to a modal shift from
private to public modes of transport. This modal shift from car and motorcycle to BRT reduced the emission intensity of primary
pollutants, such as NOx and CO. We applied a combined structural equation model and an artificial neural network to evaluate the impact of the BRT
system on the concentration of secondary pollutants in the roadside areas in the BRT corridors. An empirical analysis was
carried out using data collected at five continuous ambient air quality monitoring stations located near to the BRT TransJakarta
corridors in 2005. The establishment of our structural equation model gives a better understanding of the cause–effect relationship
among the factors influencing roadside ambient air pollution, and was useful in simplifying the complexity of our artificial
neural network model for predicting the modal shift’s impact on the PM10 values and concentration of O3. The introduction of the BRT system, and the modal shift it produced, had a greater influence on rapidly decaying pollutants,
such as PM10, than on O3 because of the exposure to near-source microenvironments, such as the roadside of the TransJakarta corridors. 相似文献
5.
The climate warming is mainly due to the increase in concentrations of anthropogenic greenhouse gases, of which CO2 is the most important one responsible for radiative forcing of the climate. In order to reduce the great estimation uncertainty of atmospheric CO2 concentrations, several CO2-related satellites have been successfully launched and many future greenhouse gas monitoring missions are planned. In this paper, we review the development of CO2 retrieval algorithms, spatial interpolation methods and ground observations. The main findings include: 1) current CO2 retrieval algorithms only partially account for atmospheric scattering effects; 2) the accurate estimation of the vertical profile of greenhouse gas concentrations is a long-term challenge for remote sensing techniques; 3) ground-based observations are too sparse to accurately infer CO2 concentrations on regional scales; and 4) accuracy is the primary challenge of satellite estimation of CO2 concentrations. These findings, taken as a whole, point to the need to develop a high accuracy method for simulation of carbon sources and sinks on the basis of the fundamental theorem of Earth’s surface modelling, which is able to efficiently fuse space- and ground-based measurements on the one hand and work with atmospheric transport models on the other hand. 相似文献
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Juozas Augutis Ričardas Krikštolaitis Rolandas Urbonas Eugenijus Ušpuras 《Stochastic Environmental Research and Risk Assessment (SERRA)》2006,21(1):51-61
In the age when transport flows in the railway and road systems, information flows in the internet channels, etc. intensify, hazard distribution in the network systems becomes a more relevant and important issue. In the paper various theoretical hazard type distributions in the network systems are analysed. Conditions and assumptions that hazard in the network system cells would settle and became steady are defined. Cases are analysed, when hazard is initiated in one or several network nodes, while in other nodes hazard is decreased, i.e. they have immunity to the hazard. In all cases hazard distribution equilibrium equations are constructed and their solutions‘ existence conditions are defined. Theoretical results are illustrated by simulation of hazard fuel transportation in the Lithuanian roads. It is shown that using this methodology it is possible to construct an algorithm, which enables to operate and decrease fuel transportation hazard and risk. The novelty of the work is associated with employing Markov process to describe hazard distribution mechanism and to determine limited hazard distribution in the nodes of networks. The hazard of tank trucks in the network of Lithuanian roads has been assessed for the first time. 相似文献
8.
本文论述了交通系统的震害,建立了城市交通系统地震救灾服务功能模型及评估方法以及救灾功能的可靠性分析方法,提出了基于可靠度的系统地震服务功能的分析方法和最佳路径优化方法,并以可靠度和道路长度作为协调参数,运用优化方法解决了交通系统安全性和经济性之间的矛盾,提出了交通系统加固优化的实用的分析方法。最后以某城市交通网络系统为例进行了分析研究,为城市交通系统防震减灾研究提供理论基础。 相似文献
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10.
Reliance on motor vehicle travel and the internal combustion engine has provided mobility, but the public health costs are
substantial: Road deaths, adverse deleterious health effects from air pollution and noise, reduction in physical exercise,
and toxic hazards associated with the refining, transport, use and disposal of petrochemicals. For traumatic road injury,
kinetic energy is the pathogen. Risks for injury and death rise with the second and fourth power of increases in velocity
upon impact; emissions of many air pollutants also increase exponentially with speed. Models derived from vector transmission
in infectious diseases have proven useful for defining risks and designing interventive strategies. These models predict the
number of lives saved and injuries prevented from a package of low-cost, effective measures, which can be quickly implemented.
Eradication of road deaths and elimination of air pollution emissions are achievable public health goals.
Speed camera systems produce sustainable levels of detection deterring speeding, and thereby reducing human injury and environmental
damage. “Education” and building more roads, part of the scenario “predict and provide,” have not been shown to reduce injury
risks. Building more roads, which in the long run, promotes urban sprawl and congestion, does not reduce travel time.
High speed toll roads and circular beltways, which involve trade-offs among time-saving, risk of injury, and diversion of
traffic from population centers, need to be re-evaluated and compared to alternative strategies based on modal shifts. We
suggest that revenues resulting from massive use of speed cameras can serve as the first step for funding the first steps
of sustainable transportation policies based on developing alternatives to private vehicle use and trucking. Such alternatives
could lead to even further reductions in injury and death and adverse effects of air pollution. More involvement by epidemiologists
in overseeing and evaluating strategies can expedite progress towards the goal of eradication of deaths from road injury,
and at the same time, reduce emissions of air pollutants.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
11.
Future sediment dynamics may be affected by changing climates or hydrological regimes because of the close link between hydrology and sediment erosion, deposition, and transport. Previously, investigations of these potential changes have been constrained by a combination of limited observational data, hydrological drivers, and appropriate mechanistic models. Additionally, there is often ambiguity regarding how to disentangle the impacts of climate and hydrology from direct human factors such as reservoirs and land‐use change, which often exert more control over sediment dynamics. In this study, we utilize a recently developed, large‐scale, distributed, mechanistic sediment transport model to project future sediment erosion, deposition, and transportation within the Fraser River Basin in British Columbia, Canada—a basin with historical water flux and sediment load observations and limited anthropogenic influences upstream of its delta. The sediment model is driven by synthetic land‐surface hydrology derived from Scenarios A1B, A2, and B1 of the Special Report on Emissions Scenarios, which were provided by the Pacific Climate Impacts Consortium. Resulting simulations of water flux and sediment load from 1965 to 1994 are first validated against observational data then compared with future projections. Future projections show an overall increase in annual hillslope erosion and in‐channel transportation, a shift towards earlier spring peak erosion and transportation, and longer persistence of the sediment signal through the year. These shifts in timing and annual yield may have deleterious effects on spawning sockeye salmon and are insufficient to counteract future coastal retreat caused by sea‐level rise. 相似文献
12.
三峡澎溪河水-气界面温室气体模型估算及其敏感性分析 总被引：2，自引：0，他引：2
模型估算法是水-气界面温室气体通量监测的主要方法,所得成果也不胜枚举.然而监测过程中诸多环境因素会对最终结果产生不确定的影响.结合三峡库区澎溪河背景条件,利用模型估算法进行水-气界面温室气体通量(以CO_2为例)估算,并且采用修正Morris筛选法尝试分析模型估算法中各个参数对温室气体扩散通量(以CO_2为例)的局部敏感性.研究结果表明:利用模型估算法计算三峡澎溪河流域水-气界面温室气体通量具有较高的可行性和可靠性;风速、水温以及pH值会对监测结果产生影响,且风速越强、水温越高、pH值越小,CO_2扩散通量就越大;pH值是高灵敏参数,风速和水温是灵敏参数.在三峡库区澎溪河监测过程中更应注意pH值的精确性,每次采样前需校正仪器. 相似文献
13.
The objective of this study is to investigate the effects of earthquakes on road vehicle-bridge coupling vibration systems. A two-axle highway freight vehicle is treated as a 13 degree-of-freedom system composed of several rigid bodies, which are connected by a series of springs and dampers. The framework of the earthquake-vehicle-bridge dynamic analysis system is then established using an earthquake as the external excitation. The equivalent lateral contact force serves as the judgment criteria for sideslip accidents according to reliability theory. The entire process of the vehicle crossing the bridge is considered for a very high pier continuous rigid frame bridge. The response characteristics of the vehicle and the bridge are discussed in terms of various parameters such as earthquake ground motion, PGA value of the earthquake, incident angle, pier height, vehicle speed and mass. It is found that seismic excitation is the most influential factor in the responses of the vehicle-bridge system and that the safety of vehicles crossing the bridge is seriously impacted by the dual excitations of earthquake and bridge vibration. 相似文献
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Malcolm Kelland 《Marine pollution bulletin》1994,29(6-12):307-311
The recent increased interest in gas hydrates has partly been the result of their potential as an energy source and for energy storage. Natural gas hydrates are found world-wide and contain vast stores of methane fuel. The estimates for the amount of methane are comparable to or even greater than conventional natural gas sources and therefore represent an extensive source of untapped energy. In addition, natural gas hydrates contain high concentrations of methane gas. This property can be exploited for natural gas transportation and storage in the form of hydrates as they can easily be stabilized at moderate pressures (10–25 bars) and temperatures (5–15°C). 相似文献
16.
Single span highway bridges of composite construction are idealized as beams as well as orthotropic plates. A standard HS–20–44 highway vehicle is represented by a planar, two-axle, sprung mass system with frictional device. The response equations are derived in terms of the natural modal co-ordinates of the bridge and of displacement co-ordinates of the vehicle. The road surface irregularities, generally found at the junctions of the approach road and bridge ends, are idealized as a 45° ramp. The maximum impact factors for bending moment and deflection are obtained due to the ramp and in combination with the braking of vehicle for symmetric as well as essentric loading of the vehicle. 相似文献
17.
Large amounts of gas can result from anaerobic corrosion of metals and from chemical and biological degradation of organic substances in underground repositories for radioactive waste. Gas generation may lead to the formation of a gas phase bubble and to the migration of radioactive gaseous species. Transport occurs in, at least, in two forms: (1) gas bubble, migration is controlled by advection, dispersion and diffusion in the gas phase, and (2) within water pockets, the dissolved species migrate mainly by diffusion. We consider a two-dimensional system representing an isolated heterogeneous fractured zone. A dipole gas flow field is generated and gas tracers are injected. The delay in the breakthrough curves is studied. A simple method is used to solve the gas species transport equations in multiphase conditions. This method is based on a formal analogy between the equations of gas transport in a two phase system and the equations of solute tracer transport in water saturated systems. We perform a sensitivity analysis to quantify the relevance of the various transport mechanisms. We find that gas tracer migration is very sensitive to gas tracer solubility, which affects gas tracer transport of both mobile and immobile zones, and shows high sensitivity to diffusion in the gas phase, to heterogeneity and to gas pressure, but the largest sensitivity was observed with respect to injection borehole properties, i.e. borehole volume and water filled fraction. 相似文献
18.
建立有限元模型是核电厂建筑结构模态分析的重要前提。本文以某高温气冷堆核电厂建筑结构为原型，在分析方法相同的前提下，建立2种不同模型（Solid模型和Shell模型），并对这2种模型进行模态分析。重点分析、对比2种模型的自振频率和振型图，计算分析表明:Solid模型与Shell模型相比，计算得到的结构自振频率值较高，但两者的差异很小，前30阶自振频率相对误差小于3.4%；2种模型的计算结构振型基本一致。研究结果可为核电厂抗震性能分析和设计提供参考。 相似文献
19.
The fluvial flux of particulate organic matter from the UK: the emission factor of soil erosion 总被引：1，自引：0，他引：1 
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下载免费PDF全文 Soil erosion has been identified as a potential global carbon sink since eroded organic matter is replaced at source and eroded material is readily buried. However, this argument has relied on poor estimates of the total fate of in‐transit particulates and could erroneously imply soil erosion could be encouraged to generate carbon stores. These previous estimates have not considered that organic matter can also be released to the atmosphere as a range of greenhouse gases, not only carbon dioxide (CO2), but also the more powerful greenhouse gases methane (CH4) and nitrous oxide (N2O). As soil carbon lost by erosion is only replaced by uptake of CO2, this could represent a considerable imbalance in greenhouse gas warming potential, even if it is not significant in terms of overall carbon flux. This work therefore considers the flux of particulate organic matter through UK rivers with respect to both carbon fluxes and greenhouse gas emissions. The results show that, although emissions to the atmosphere are dominated by CO2, there are also considerable fluxes of CH4 and N2O. The results suggest that soil erosion is a net source of greenhouse gases with median emission factors of 5.5, 4.4 and 0.3 tonnes CO2eq/yr for one tonne of fluvial carbon, gross carbon erosion and gross soil erosion, respectively. This study concludes that gross soil erosion would therefore only be a net sink of both carbon and greenhouse gases if all the following criteria are met: the gross soil erosion rate were very low (<91 tonnes/km2/yr); the eroded carbon were completely replaced by new soil organic matter; and if less than half of the gross erosion made it into the stream network. By establishing the emission factor for soil erosion, it becomes possible to properly account for the benefits of good soil management in minimizing losses of greenhouse gases to the atmosphere as a by‐product of soil erosion. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
20.
Rolf K. Eckhoff 《Marine pollution bulletin》1994,29(6-12):304-306
Natural gas (NG) is produced whenever organic matter is decomposed in the absence of oxygen. The main constituent of natural gas is methane. In contrast to liquid fuels, methane has a boiling point far below normal ambient temperatures. Even the critical temperature is well below ambient. Therefore natural gas must be stored either as compressed natural gas (CNG) at very high pressures at ambient temperatures, or as liquefied natural gas (LNG) at very low temperatures. The basic safety issues are caused by loss of confinement of either CNG or LNG. In both cases the issues are: global greenhouse effects of natural gas (methane); local fire and explosion hazards; and local asphyxiation hazard due to reduced oxygen content in the atmosphere breathed when air is mixed with methane. 相似文献