379 research outputs found
Impacts on modal choices of new generation freights terminals
Increasing pollution, congestion of roads and worries about the spatial and environmental impacts of road transports have promoted the idea of transferring part of freight transportation from roads to railways and waterways. Given the limited density of these two modes' networks, this policy implies necessarily the development of inter-modal transports. But their operation on a large scale is meeting several problems : the additional cost of transferring the commodities from one mode or means to another, the size of investments in new technology equipment for terminals, specialized rolling stock and information systems, the involvement of several intermediaries plus the control and management of safety and reliability of the services. In the past, many innovative plans and projects for bundling and transshipping were developed, but many plans were abandoned, and despite a steady growth of inter-modal transports, the results obtained are still limited. At the present time, the most promising projects seem to be the introduction of new shuttle connections on transport links with important flows of transports. However, lower costs and better management of services could probably make attractive the organization of more complex schemes like hub-and-spokes organizations. The paper presents a methodology to model bundling concepts on multi-modal freight networks. It is based on the extensive use of virtual links as they are implemented in the NODUS software developed by GTM . Different configurations of inter-modal networks are modeled which are implemented in a digitized trans-European multi-modal network (rail, road and waterway). Cost functions are associated with every (virtual) link which corresponds to a particular transport operation. A matrix of origins and destinations throughout the European space is generated on the basis of global EUROSTAT statistics by the use of a weighted stochastic procedure. Given this transportation task a minimization of generalized costs can be made which assigns transport flows between paths, modes and means of transport. Hence, successive simulations for different configurations and various parameters' values provide a set of measures of their impacts, which can be used for assessing the interest of concrete inter-modal propositions. The indicators are the market shares, the total operating cost of the transportation task, the total cost of a particular operation, the distances covered, the times of transport, the service frequency required, the energy consumption, etc. This research is part of the EU Commission's TERMINET project which focuses on the potentialities of innovative bundling concepts for transport nodes and terminals.
Freight Transportation Planning on the European Multimodal Network: the case of the Walloon Region
This paper presents a methodology that can be used for long-term planning of freight transportation on multimodal networks. It is illustrated by research carried out for the Belgian Walloon Ministry of Transport between 1997 and 1999. Its aim was to provide a tool for measuring the impacts of different kinds of policies and/or new infrastructures on freight transport flows in and through Wallonia. The work started with the setting up of a calibrated multimodal and multi-products reference scenario for the year 1995. This reference scenario was then used as a basis to create a projection for the year 2010: in order to make this projection as realistic as possible, all the decided new infrastructures in Belgium and in the border countries that will be effective in 2010 were introduced in the model. Moreover, expected changes in the O-D matrixes were also introduced at a very detailed level. Then, a set of scenarios was build: one for each transportation mode in which specific changes for that mode were introduced, and one in which the external costs of transport were taken into account. On the basis of the obtained results, a ætransportation planÆ was built, in which the most promising changes in the different networks and policies were chosen. A sensitivity analysis (low and high economic activity) was finally performed
Rail-Road terminal locations: aggregation errors and best potential locations on large networks
In network location problems, the number of potential locations is often too large in order to find a solution in a reasonable computing time. That is why aggregation techniques are often used to reduce the number of nodes. This reduction of the size of the location problems makes them more computationally tractable, but aggregation introduces errors into the solutions. Some of these errors will be estimated in this paper. A method that helps to isolate the best potential locations for rail-road terminals embedded in a hub-and-spoke network will further be outlined. Hub location problems arise when it is desirable to consolidate flows at certain locations called hubs. The basic idea is to use the flows of commodities and their geographic spreading as input to determine a set of potential locations for hub terminals. The exercise will be done for the trans-European networks. These potential locations can then further be used as input by an optimal location method
Carpooling and employers: a multilevel modelling approach
Both public policy-makers and private companies promote carpooling as a commuting alternative in order to reduce the number of Single Occupant Vehicle (SOV) users. The Belgian questionnaire Home-To-Work-Travel (HTWT) is used to examine the factors which explain the share of carpooling employees at a worksite. The modal split between carpooling and rail use was also subject of the analysis. The number of observations in the HTWT database (n=7460) makes it possible to use more advanced statistical models: such as multilevel regression models which incorporate, next to the worksite level, also the company and economic sector levels. As a consequence, a more employer-oriented approach replaces the traditional focus of commuting research on the individual. Significant differences in modal split between economic sectors appeared. The most carpool-oriented sectors are construction and manufacturing, while rail transport is more popular in the financial and public sector. Carpooling also tend to be an alternative at locations where rail is no real alternative. Next to this, regular work schedules and smaller sites are positively correlated with a higher share of carpooling employees. Finally, no real evidence could be found for the effectiveness of mobility management measures which promote carpooling. However, most of these measures are classified in the literature as less effective and a case study approach should complete the research on mobility management initiatives
From research to farm : ex ante evaluation of strategic deworming in pig finishing
This paper upgrades generic and partial information from parasitological research for farm-specific decision support, using two methods from managerial sciences: partial budgeting and frontier analysis. The analysis focuses on strategic deworming in pig finishing and assesses both effects on economic performance and nutrient efficiency. The application of partial budgeting and frontier analysis is based on a production-theoretical system analysis which is necessary to integrate parasitological research results to assess aggregate economic and environmental impacts. Results show that both statistically significant and insignificant parasitological research results have to be taken into account. Partial budgeting and frontier analysis appear to be complementary methods: partial budgeting yields more discriminatory and communicative results, while frontier methods provide additional diagnostics through exploring optimization possibilities and economic-environmental trade-offs. Strategic deworming results in a win-win effect on economic and environmental performances. Gross margin increases with 3 to 12 € per average present finisher per year, depending on the cyclic pig price conditions. The impact on the nutrient balance ranges from +0.2 to –0.5 kg nitrogen per average present finisher per year. The observed efficiency improvements are mainly technical and further economic and environmental optimizations can be achieved through input re-allocation. A user-friendly spreadsheet is provided to translate the generic experimental information to farm-specific conditions
CRISPR-TSKO : a technique for efficient mutagenesis in specific cell types, tissues, or organs in Arabidopsis
Detailed functional analyses of many fundamentally important plant genes via conventional loss-of-function approaches are impeded by the severe pleiotropic phenotypes resulting from these losses. In particular, mutations in genes that are required for basic cellular functions and/or reproduction often interfere with the generation of homozygous mutant plants, precluding further functional studies. To overcome this limitation, we devised a clustered regularly interspaced short palindromic repeats (CRISPR)-based tissue-specific knockout system, CRISPR-TSKO, enabling the generation of somatic mutations in particular plant cell types, tissues, and organs. In Arabidopsis (Arabidopsis thaliana), CRISPR-TSKO mutations in essential genes caused well-defined, localized phenotypes in the root cap, stomatal lineage, or entire lateral roots. The modular cloning system developed in this study allows for the efficient selection, identification, and functional analysis of mutant lines directly in the first transgenic generation. The efficacy of CRISPR-TSKO opens avenues for discovering and analyzing gene functions in the spatial and temporal contexts of plant life while avoiding the pleiotropic effects of system-wide losses of gene function
Gene List Automatically Derived For You (GLAD4U): deriving and prioritizing gene lists from PubMed literature
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