论粮食筒仓项目建设中除尘系统的选型与安装

本文主要论述除尘系统设计、选型、安装等相关问题,重点就除尘系统安装及调试过程中可能遇到的一些问题进行论述,以减少设备安装阻碍、保证调试工作顺利进行。     

Carbon footprint of tourism in Barcelona

This study evaluates the carbon footprint (CF) of Barcelona tourist activity taking into account the above 30 million visitors who visit the city every year. This study analyzes the main sources of emissions considering direct (Scope 1) and indirect emissions (Scope 2 and 3) as a consequence of energy use. This research has been carried out in close collaboration with Barcelona City Council and in the context of the new Strategic Tourism Plan for Barcelona city. The impacts of arrival and departure transport, accommodation, leisure and professional activities and Intra-urban transport from Barcelona city were all included. The total CF of Barcelona tourist activity is about 9.6MtCO₂eq/year, which represents an emission of 96.9 kg CO₂eq/visitor·day. The main source of emissions is arrival and departure transport (95.6%), and particularly aviation. These results show that if substantial reductions in CO₂ emissions are to be achieved, initiatives strategically focused on transport and also accommodation are necessary.     

Algebraic connectivity maximization of an air transportation network: The flight routes’ addition/deletion problem

A common metric to measure the robustness of a network is its algebraic connectivity. This paper introduces the flight routes addition/deletion problem and compares three different methods to analyze and optimize the algebraic connectivity of the air transportation network. The Modified Greedy Perturbation algorithm (MGP) provides a local optimum in an efficient iterative manner. The Weighted Tabu Search (WTS) is developed for the flight routes addition/deletion problem to offer a better optimal solution with longer computation time. The relaxed semidefinite programming (SDP) is used to set a performance upper bound and then three rounding techniques are applied to obtain feasible solutions. The simulation results show the trade-off among the Modified Greedy Perturbation, Weighted Tabu Search and relaxed SDP, with which we can decide the appropriate algorithm to adopt for maximizing the algebraic connectivity of the air transportation networks of different sizes. Finally a real air transportation network of Virgin America is investigated.     

Do the regional growth effects of air transport differ among airports?

This paper empirically studies the contribution of air transport to regional economic development in Germany. We find that the scale and direction of output effects of air services and airport infrastructure differ among airports. These differences are driven by ‘opportunity costs’ of airport capital and by positive output effects from air transport connectivity. We argue that the latter impacts potentially depend on traffic characteristics.     

Emissions and exposure costs of electric versus conventional vehicles: A case study in Texas

The emissions and human exposure impacts of electric vehicle (EV) adoption, especially in comparison to conventional gasoline- or diesel-powered engines, depend on numerous factors including geography, electricity generation, and fuel mix. Results of any analysis also vary depending on the nature of data collected and their level of aggregation by time or location. This paper combines several approaches to develop a robust estimate of these impacts specific to the state of Texas by considering marginal emissions by time of day, as well as location of vehicle and power plant emissions. The authors estimate health and other external costs of operating an EV in the state at approximately $62 per year, compared with an average of $136 for a passenger car powered by gasoline.     

Urban bus fleet-to-route assignment for pollutant emissions minimization

This study proposes a methodology to optimize the assignment of an urban bus fleet to a set of fixed routes, taking into account the differences among routes and the differences among vehicle types and propulsion technologies in order to reduce pollutant emissions (CO₂, CO, THC, NO_x and PM). A Mixed Integer Linear Programming optimization model is stated and two scenarios are assessed: minimization of CO₂ and NO_x. The results show that it is feasible to obtain a fleet distribution in which emissions for any given pollutant are reduced without increase in emissions of other pollutants.     

Postcard reminders versus replacement questionnaires and mail survey response rates from a professional population

Nonresponse is a major problem in the use of mail questionnaires. The great number of variables that can influence response rates has resulted in an extensive literature on the subject, but a literature that is restricted to few examples of replication. Moreover, many of the studies reported in the literature were not conducted under controlled conditions. This article presents the results of a study using a single-factor experimental design to test the efficacy of two different follow-up forms in improving response rates. The results indicate that replacement questionnaires are to be preferred over postcard reminders when using a one-time follow-up in surveying a professional population.     

Making or breaking - Key success factors in the air cargo market

This introductory paper considers a number of major evolutions in the air freight market. In the first instance, it describes the heterogeneous environment in which air cargo services are performed. Subsequently, it looks at some of the most notable developments in air freight. Lastly, it deals with the market structure and with possible future strategies.     

A transport carbon footprint methodology to assess airport carbon emissions

Airports are important nodes in the air transport system, but also local sources of environmental impacts. Emissions of CO₂ are among the most relevant ones because of their potential greenhouse effects. Many policies and guidelines have been identified at national and world level to reduce such kind of impacts. In this paper, a Transport Carbon Footprint methodology has been set to identify Unit Carbon Footprints (UCFs) linked to some identified emission macro-sources – i.e., land vehicles, on-ground aircraft, airport handling and terminal equipment – to compute the contribution of the single macro-source to the total amount of CO₂. Particularly, UCFs due to transport activities have been defined according to some relevant transport variables. The computation of UCF values for a given airport allows computing both the contribution of each macro-source and also evaluating the effectiveness of transport-related actions aiming at reducing the carbon impact. The methodology has been applied to the airport of Bologna, in Northern Italy, and its UCF values for the identified macro-sources have been computed.     

‘The trauma of competition’: The entry of Air Products Inc. into the industrial gases business in Britain and continental Europe, 1947–70

The British Oxygen Company (BOC) had a virtual monopoly on the supply of industrial gases (e.g. oxygen and acetylene) on the British market through the 1950s, when it was finally challenged by an American-based company, Air Products. Air Products Limited (APL) was able to undercut BOC's position, overcoming high barriers to entry to gain significant market share in this sector, which shares some features of network industries. Factors in this success included conditions imposed by the Board of Trade, APL's innovations, BOC's slow response, and favourable market conditions. APL's success had implications for the internationalisation of the industrial gases industry.