212 research outputs found
Taxis Dispatch: Minimizing waiting times by maximizing coverage
No full textIn this thesis, we investigate whether maximizing the coverage of taxis can be beneficial when the goal is to minimize the waiting times of the clients. When dispatching taxis, often only current requests are taken into account and not future ones. We examined how beneficial it can be to take coverage into account. For taxi companies it is important to keep their customers satisfied, by serving them as quickly as possible. Often companies assign the taxis to the nearest requests. We investigate whether there are better dispatch methods. We developed three dispatch policies which use ILP models, and discussed what the best option is. The first policy does not consider the coverage and minimizes the waiting times of the clients among the requests that are taking place at that moment. The second one aims to maintain a good coverage and short waiting times when assigning taxis to requests. The third one also aims to maintain a good coverage and short waiting times when assigning taxis to requests and also relocates taxis to gain a better covered area. Those policies can be a contribution for taxi companies because they help to serve clients more quickly. To determine what the best way is of dispatching taxis, we run a simulation on the different policies on a real-data map and compared the results. The literature over taxi dispatch mostly conducts research on a small area like a city or a village. In this thesis, taxis dispatch takes place on a larger area where taxis commute between cities
Taxis limiting borders
No full textБобкова Елена Александровна, кандидат филологических наук, доцент кафедры английской филологии, Бирский филиал Башкирского государственного университета (г. Бирск), [email protected]. E.A. Bobkova, Bashkir State University, Birsk Affiliation, Birsk, Russian Federation, [email protected]Раскрываются некоторые аспекты категории таксиса на материале английского языка,
упоминаются несколько научных школ, занимающихся проблемой таксиса, отмечается связь
таксиса с другими темпоральными категориями – времени, вида, временной отнесенности;
возможность передачи нескольких таксисных ситуаций, образующих разные временные периоды в рамках одного предложения. Предлагается расширение границ таксиса за счет включения в таксисные отношения конструкций с придаточным изъяснительным в модусдиктумных комплексах в режиме нарратива при несовпадении времени модуса с моментом
речи как точкой отсчета. Обращается внимание на необходимость выделения точки отсчета
для определения таксисных отношений. Точкой отсчета при этом является первая пропозиция полипредикативного комплекса. Предлагается применять понятие зависимого и независимого таксиса только по отношению к способам выражения таксисных отношений. С семантической точки зрения все пропозиции полипредикативного комплекса представляются зависимыми от пропозиции, принятой за точку отсчета. Таксисные отношения одновременности/
предшествования/ следования дополняются еще одним отношением – последовательности,
что характерно для предложений с однородными сказуемыми и сложносочиненных предложений с поступательным развитием передаваемой ситуации. В статье подтверждаются наблюдения А.В. Бондарко, касающиеся совмещения таксиса с отношениями характеризации,
модальности, обусловленности. The article deals with certain aspects of the category of taxis on the basis of the English language.
A few schools of thought are mentioned in connection with taxis; the relation of taxis with
other temporal categories is touched upon, such as tense, aspect, and time correlation. The article
focuses on the possibility of rendering several taxis situations making up different temporal periods
within one sentence. Expansion of taxis volume is suggested through the inclusion of constructions
with object clauses in modus-dictum complexes in the narrative mode into taxis relations on the
condition that the modus tense does not coincide with the moment of speech as a starting point. The
starting point is the first proposition of a poly-predicative complex. The author suggests that the notion
of dependent and independent taxis should be used only in reference to means of expressing
taxis relations. From the semantic point of view all the propositions of a poly-predicative complex
are considered to be dependent on the proposition taken as a starting point. Taxis relations of simultaneity/
precedence/ following are enlarged by adding one more relation, that of succession, which
is characteristic of sentences with homogeneous predicates and compound sentences of a successive
development of the situation rendered. The article confirms A.V. Bondarko’s observations concerning
the combination of taxis with relations of characterization, modality, conditionality
THE REALIZATION OF THE QUALITY SEMANTICS IN ENGLISH (ON THE EXAMPLE OF TAXIS SEMANTICS)
No full textThe article examines the functioning of the structures containing nuclear components of autonomous taxis when realizing the function of synchronicity in English. The study is conducted by the material of modern fiction. The author analyzes literary personages’ direct speech and discovers the typical peculiarities of the taxis semantics of synchronicity realization in col- loquial speech. Then the researcher compares adults’ and children’s speech spheres and identifies similarities and differences between them
Water Taxis in the San Francisco Bay Area: From travel time to quality time: Is there a viable service concept?
No full textThis thesis presents a discrete-choice model as the basis to forecast market shares for high-end water taxis in the San Francisco Bay Area. Waterborne mobility studies are growing in numbers, but studies towards the potential of personalized versions thereof is scarce. Three service concepts are designed as business models and compared on business potential. It is surprising to see that, compared to the very low public transit prices, this service still seems to reach market shares of 10% at ticket prices of up to $50 per single trip.Transport and Logistics' OrganisationTechnology, Policy and Managemen
Evolution of taxis responses in virtual bacteria: non-adaptive dynamics.
No full textCopyright: © 2008 Goldstein, Soyer. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.Bacteria are able to sense and respond to a variety of external stimuli, with responses that vary from stimuli to stimuli and from species to species. The best-understood is chemotaxis in the model organism Escherichia coli, where the dynamics and the structure of the underlying pathway are well characterised. It is not clear, however, how well this detailed knowledge applies to mechanisms mediating responses to other stimuli or to pathways in other species. Furthermore, there is increasing experimental evidence that bacteria integrate responses from different stimuli to generate a coherent taxis response. We currently lack a full understanding of the different pathway structures and dynamics and how this integration is achieved. In order to explore different pathway structures and dynamics that can underlie taxis responses in bacteria, we perform a computational simulation of the evolution of taxis. This approach starts with a population of virtual bacteria that move in a virtual environment based on the dynamics of the simple biochemical pathways they harbour. As mutations lead to changes in pathway structure and dynamics, bacteria better able to localise with favourable conditions gain a selective advantage. We find that a certain dynamics evolves consistently under different model assumptions and environments. These dynamics, which we call non-adaptive dynamics, directly couple tumbling probability of the cell to increasing stimuli. Dynamics that are adaptive under a wide range of conditions, as seen in the chemotaxis pathway of E. coli, do not evolve in these evolutionary simulations. However, we find that stimulus scarcity and fluctuations during evolution results in complex pathway dynamics that result both in adaptive and non-adaptive dynamics depending on basal stimuli levels. Further analyses of evolved pathway structures show that effective taxis dynamics can be mediated with as few as two components. The non-adaptive dynamics mediating taxis responses provide an explanation for experimental observations made in mutant strains of E. coli and in wild-type Rhodobacter sphaeroides that could not be explained with standard models. We speculate that such dynamics exist in other bacteria as well and play a role linking the metabolic state of the cell and the taxis response. The simplicity of mechanisms mediating such dynamics makes them a candidate precursor of more complex taxis responses involving adaptation. This study suggests a strong link between stimulus conditions during evolution and evolved pathway dynamics. When evolution was simulated under conditions of scarce and fluctuating stimulus conditions, the evolved pathway contained features of both adaptive and non-adaptive dynamics, suggesting that these two types of dynamics can have different advantages under distinct environmental circumstances
CROWDDELIVER: Planning City-Wide Package Delivery Paths Leveraging the Crowd of Taxis
No full textDespite the great demand on and attempts at package express shipping services, online retailers have not yet had a practical solution to make such services profitable. In this paper, we propose an economical approach to express package delivery, i.e., exploiting relays of taxis with passengers to help transport package collectively, without degrading the quality of passenger services. Specifically, we propose a two-phase framework called CROWDDELIVER for the package delivery path planning. In the first phase, we mine the historical taxi trajectory data offline to identify the shortest package delivery paths with estimated travel time given any Origin-Destination pairs. Using the paths and travel time as the reference, in the second phase we develop an online adaptive taxi scheduling algorithm to find the near-optimal delivery paths iteratively upon real-time requests and direct the package routing accordingly. Finally, we evaluate the two-phase framework using the real-world data sets, which consist of a point of interest, a road network, and the large-scale trajectory data, respectively, that are generated by 7614 taxis in a month in the city of Hangzhou, China. Results show that over 85% of packages can be delivered within 8 hours, with around 4.2 relays of taxis on average.National Science Foundation of China [61602067, 61572048]; Fundamental Research Funds for the Central Universities [106112015CDJXY180001]; Chongqing Basic and Frontier Research Program [cstc2015jcyjA00016]; Open Research Fund Program of the Shenzhen Key Laboratory of Spatial Smart Sensing and Services, Shenzhen UniversitySCI(E)ARTICLE61478-14961
Automated taxis’ dial-a-ride problem with ride-sharing considering congestion-based dynamic travel times
No full textIn this paper, we study the dial-a-ride problem of ride-sharing automated taxis (ATs) in an urban road network, considering the traffic congestion caused by the ATs. This shared automated mobility system is expected to provide a seamless door-to-door service for urban travellers, much like what the existing transportation network companies (TNC) do, but with decreased labour cost and more flexible relocation operations due to the vehicles’ automation. We propose an integer non-linear programming (INLP) model that optimizes the routing of the ATs to maximize the system profit, depending on dynamic travel times, which are a non-linear function of the ATs’ flows. It is important to involve traffic congestion in such a routing problem since for a growing number of ATs circulating in the city their number will lead to delays. The model is embedded within a rolling horizon framework, which divides a typical day into several horizons to deal with the real-time travel demand. In each horizon, the routing model is solved with the demand at that interval and assuring the continuity of the trips between horizons. Nevertheless, each horizon model is hard to solve given its number of constraints and decision variables. Therefore, we propose a solution approach based on a customized Lagrangian relaxation algorithm, which allows identifying a near-optimal solution for this difficult problem. Numerical experiments for the city of Delft, The Netherlands, are used to demonstrate the solution quality of the proposed algorithm as well as obtaining insights about the AT system performance. Results show that the solution algorithm can solve the proposed model for hard instances. Ride-sharing makes the AT system more capable to provide better service regarding delay time and the number of requests that can be attended by the system. The delay penalty on the profit objective function is an effective control parameter on guaranteeing the service quality while maintaining system profitability.Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Transport and Plannin
Inventário de basidiomycetes lignolíticos em Santa Catarina: guia eletrônico
No full textDissertação (mestrado) - Universidade Federal de Santa Catarina, Centro de Ciências Biológicas. Programa de Pós-Graduação em Biologia Vegetal.A necessidade de divulgação entre a comunidade científica das informações sobre micodiversidade no estado de Santa Catarina, levou à organização deste inventário na forma de um Guia Interativo Eletrônico. O Banco de Dados recebeu a denominação de Basidiomycetes em Santa Catarina (BASC). Foram catalogadas as espécies de fungos lignolíticos no Estado através de levantamentos da bibliografia, assim como análises das coleções (herbário FLOR) referentes a 22 anos de pesquisas. Para criar o Banco de Dados, foi utilizado o software TAXIS 3.5 Professional, que incorporou todas as informações obtidas. Atualmente o BASC inclui 1.280 coletas que correspondem a 153 espécies de Basidiomycetes xilófilos encontradas ao longo de 88 localidades (36 municípios) do Estado, além de 1.139 imagens e uma matriz de identificação com 25 caracteres. Mycobonia flava e Stiptophyllum erubescens são descritas pela primeira vez para Santa Catarina. Esta é uma ferramenta taxonômica que contém amplas informações sobre as espécies e permite estimar a diversidade e a variação quantitativa por localidades e regiões. Este inventário eletrônico também facilita a divulgação de conhecimento sobre a micota catarinense, permite a identificação de espécies e o monitoramento da biodiversidade no Estado. Tais ações contribuem para alertar aos pesquisadores sobre a importância de conservar a biodiversidade, primeiro passo para futuras propostas de manejo e conservação da micota
A bi-level framework for heterogeneous fleet sizing of ride-hailing services considering an approximated mixed equilibrium between automated and non-automated traffic
No full textRide-hailing companies will face the emergence and gradual expansion of AVs-only zones in urban areas where only automated vehicles (AVs) are allowed to circulate. When owning a mixed fleet (automated and conventional taxis), a ride-hailing company has to determine the optimal fleet size as a function of the gradually expanding coverage of AVs-only zones while taking into account interactions with privately-owned human-driven vehicles. To model this problem, we propose a bi-level framework in which the lower level captures the mixed routing behaviour of the vehicles and the endogenous traffic congestion, and the upper level determines fleet sizes to maximise profit. A parallel genetic algorithm is introduced to solve this bi-level framework, which is embedded with a tailored algorithm for solving the lower-level model. Numerical experiments are conducted on instances based on a small network and the network of the city of Delft, The Netherlands, to demonstrate the performance of the proposed solution method and investigate the impacts of AVs-only zones on traffic and ride-hailing operations. Results indicate that the fleet size of automated taxis increases nonlinearly with the expansion of the AVs-only zone while that of conventional taxis decreases as demand shifts from human-driven vehicles to automated taxis. The fleet size decision depends heavily on the fleet's cost structure, the location and the distribution of parking depots. Furthermore, the existence of an AVs-only zone leads to detours for human-driven vehicles in the early stages, but it will bring major benefits by reducing congestion as its size increases.Discrete Mathematics and OptimizationTransport and Plannin
An Introduction to Trip-Assignments in Autonomous Taxis Networks: A new proposed model and parallelization
No full textWith the proliferation of autonomous vehicle technologies by companies like Waymo, Amazon, Tesla, etc., there is a need for research that studies the properties of autonomous vehicles systems before they become ubiquitous. A practical research model in this field is autonomous taxi networks (ATN). ATN are simple and parallelizable, and they provide a general and measurable view of how an autonomous vehicles system would behave.
This thesis studies a recently developed ATN model and seeks to improve it through two modifications: pixel saturation and k-means clustering. Additionally, a new methodology is developed that parallelizes trip assignment experiment/simulations within ATN models, setting up a mechanism to perform easy, quick trip assignment experiments. The results after testing the new model indicate that using k-means clustering to aggregate trips reduces the number of vehicle initialization at the cost of increasing total distance traveled. The results about pixel saturation were inconclusive, suggesting that further research in its parameterization is required to come to analytical conclusions
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