12 research outputs found

    Optimization of street lane usage

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    This paper contributes to discussion on introduction of exclusive lane for public transport. Analyses of results have been presented on effectiveness of usage of a 4 - lane and a 6 - lane street with and without an exclusive lane for buses. Two basic sub-models have been applied: - the binary logit model for modal split estimation; it takes into consideration the relation of travel time performed by private cars to public transport, - the polynomial model for predicting link impedance; the real travel time is affected by relation of traffic volume to the design capacity The parameters of both sub-models have been calibrated for the Polish conditions. The relationships are determined between number of person trips and traffic volume of buses/private cars, market share of public transport in motorised trips, average travel time lost in trips, average operation cost. An iterative technique addresses a feedback between the modal split and traffic volumes. Numerical calculations by use of EXCEL and MATLAB were carried out. Typical values of corridor length, occupancy rate of passenger car, design capacity of the bus, access and egress time to and from the parking/bus-stop in urban areas were applied. On the basis of the estimated results, the marginal parameter values: number of people carried at which separated lane for buses is most effective , traffic volume for private cars, traffic volume for buses and share of public transport in trips have been got by consideration of the average travel time lost and operational cost as criteria: Then introduction of street lanes with and without exclusive lane for buses in relation to number of person trips can be optimized

    Optimization of street lane usage

    Get PDF
    This paper contributes to discussion on introduction of exclusive lane for public transport. Analyses of results have been presented on effectiveness of usage of a 4 - lane and a 6 - lane street with and without an exclusive lane for buses. Two basic sub-models have been applied: - the binary logit model for modal split estimation; it takes into consideration the relation of travel time performed by private cars to public transport, - the polynomial model for predicting link impedance; the real travel time is affected by relation of traffic volume to the design capacity The parameters of both sub-models have been calibrated for the Polish conditions. The relationships are determined between number of person trips and traffic volume of buses/private cars, market share of public transport in motorised trips, average travel time lost in trips, average operation cost. An iterative technique addresses a feedback between the modal split and traffic volumes. Numerical calculations by use of EXCEL and MATLAB were carried out. Typical values of corridor length, occupancy rate of passenger car, design capacity of the bus, access and egress time to and from the parking/bus-stop in urban areas were applied. On the basis of the estimated results, the marginal parameter values: number of people carried at which separated lane for buses is most effective , traffic volume for private cars, traffic volume for buses and share of public transport in trips have been got by consideration of the average travel time lost and operational cost as criteria: Then introduction of street lanes with and without exclusive lane for buses in relation to number of person trips can be optimized

    The Use of Activity Chain Models to Analyse Stochastic Travel Demand

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    For analysis and planing of transport networks detailed information concerning travel sequences is required. The paper examines an activity chain model to determine stochastic travel demand which individual generates in order to participate in activity or sequence of activities over the day. The transition from one activity to another depends on the activity participation decision, which is made sequentially and is constrained in space and time. Activity chains derived from travel survey data are used as a base to develop a more realistic model than conventional discrete trip models. Probabilistic concepts and statistical procedures are used to estimate characteristics of travel demand such as the number of daily out-of-home activities and transition probability from one activity to another participated by homogeneous behavioural groups. In addition, the paper compares the model for two different sized towns

    Characterisation of productivity and diseases affecting dairy goats in smallholder systems of Greater Thika Region, Kenya

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    The current cross-sectional study aimed at characterising the productivity and diseases affecting dairy goats kept by smallholder farmers in three sub-counties in Thika Region, Kenya. Standard questionnaires were administered to 240 farmers through face-to-face interviews and the outputs were analysed using descriptive and inferential statistics. The farmers mainly kept crosses of Toggenburg (45.9 %), Kenyan Alpine (29.5 %) and Saanen (17.4 %) dairy goats. The average dairy goat flock size was 4.5 (range 1–23) and 77.5 % of the goats were kept for production of milk for domestic consumption. The average milk production per goat per day was 1.26 litres (range 0.5 to 3.5 litres) and was significantly (p 0.05) associated with sub-county of origin, main occupation of the owner, breed, and lactation stages. Goats were mainly fed on napier grass, maize stovers, natural grass and hay; and these feeds did not influence (p 0.05) the milk production levels. The farmers identified helminthosis (84.6 %), pneumonia (32.9 %), coccidiosis (25.8 %) and mastitis (25 %), as the most prevalent goat diseases. In conclusion, the study showed that dairy goat farming in greater Thika Region was characterised by low-input with an objective of provision of milk for home consumption. The observed challenges of low milk productivity and diseases should be addressed by the local extension workers through training on improved husbandry, nutrition and health management of the dairy goats

    'This was a Conradian world I was entering': Postcolonial river-journeys beyond the Black Atlantic in Caryl Phillips's work

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    Caryl Phillips has been accused of replicating the stereotyped view of a timeless, ahistorical Africa that Paul Gilroy puts forward in his paradigm of the Black Atlantic. Yet this article shows that Crossing the River and Phillips’s essays about Africa suggest ways in which Gilroy’s important paradigm of the black Atlantic could be broadened to become more inclusive of writing about Africa. Phillips draws inspiration from writers such as V S Naipaul, Chinua Achebe, and especially Joseph Conrad, to update the literary journey upriver and make it relevant to contemporary West African issues. A complex interplay of racial identities occurs when people from the African diaspora travel to Africa; this is a key preoccupation for Phillips when he rewrites Conrad. During the course of his river-journeys, Phillips meditates upon the complexities of being a black Westerner in Africa, examines the memory of slavery, colonialism and postcolonial unrest, problematises diasporan attempts to ‘return’ to Africa, and recognises the longstanding modernity of African countries

    Experimental characterization of scattering from the trihedral corner reflector in the E-band

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    Abstract Canonical objects with known radar cross section (RCS), for example, the trihedral corner reflector (TCR), play a crucial role in the calibration of automotive radar sensors. Moreover, these canonical objects are also used in the validation of simulated RCS obtained using asymptotic methods, such as hybrid geometric optics (GO) and the physical optics (PO) based methods. However, accurate RCS prediction with asymptotic methods is highly dependent on the individual scattering mechanisms considered in a simulation, for example reflection and diffraction from the TCR surfaces and edges, respectively. Reliable measurements are therefore required to evaluate if a particular interaction mechanism can be neglected to reduce computation complexity without adversely affecting the accuracy of the predicted RCS. In this letter, the monostatic scattering characteristics of three metallic TCRs are investigated with varying geometrical sizes in the E-band, that is, from 60 GHz to 90 GHz. The ultra-wideband (UWB) measurements, which offer a high delay resolution, can enable the identification of the individual scattering mechanisms. Diffraction from the TCR edges is experimentally demonstrated to contribute to a non-negligible scattered power in this frequency band

    Expanding standards in viromics: in silico evaluation of dsDNA viral genome identification, classification, and auxiliary metabolic gene curation.

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    BackgroundViruses influence global patterns of microbial diversity and nutrient cycles. Though viral metagenomics (viromics), specifically targeting dsDNA viruses, has been critical for revealing viral roles across diverse ecosystems, its analyses differ in many ways from those used for microbes. To date, viromics benchmarking has covered read pre-processing, assembly, relative abundance, read mapping thresholds and diversity estimation, but other steps would benefit from benchmarking and standardization. Here we use in silico-generated datasets and an extensive literature survey to evaluate and highlight how dataset composition (i.e., viromes vs bulk metagenomes) and assembly fragmentation impact (i) viral contig identification tool, (ii) virus taxonomic classification, and (iii) identification and curation of auxiliary metabolic genes (AMGs).ResultsThe in silico benchmarking of five commonly used virus identification tools show that gene-content-based tools consistently performed well for long (≥3 kbp) contigs, while k-mer- and blast-based tools were uniquely able to detect viruses from short (≤3 kbp) contigs. Notably, however, the performance increase of k-mer- and blast-based tools for short contigs was obtained at the cost of increased false positives (sometimes up to ∼5% for virome and ∼75% bulk samples), particularly when eukaryotic or mobile genetic element sequences were included in the test datasets. For viral classification, variously sized genome fragments were assessed using gene-sharing network analytics to quantify drop-offs in taxonomic assignments, which revealed correct assignations ranging from ∼95% (whole genomes) down to ∼80% (3 kbp sized genome fragments). A similar trend was also observed for other viral classification tools such as VPF-class, ViPTree and VIRIDIC, suggesting that caution is warranted when classifying short genome fragments and not full genomes. Finally, we highlight how fragmented assemblies can lead to erroneous identification of AMGs and outline a best-practices workflow to curate candidate AMGs in viral genomes assembled from metagenomes.ConclusionTogether, these benchmarking experiments and annotation guidelines should aid researchers seeking to best detect, classify, and characterize the myriad viruses 'hidden' in diverse sequence datasets

    Genetic diversity and geographic distribution of Bemisia tabaci and Trialeurodes vaporariorum in Costa Rica

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    The tobacco whitefly Bemisia tabaci (Gennadius) cryptic species complex and of the greenhouse whitefly Trialeurodes vaporariorum (Westwood) are extensively reported as destructive pests in vegetable crops worldwide. A survey was conducted in 2011 and 2012 to determine the occurrence and genetic diversity present in the populations of these whiteflies in the major vegetable production areas of Costa Rica. Insect samples were collected from sweet pepper (Capsicum annuum L.), tomato (Solanum lycopersicum L.), common bean (Phaseolus vulgaris L.) and weeds present in commercial crops either in open field or greenhouse conditions. PCR-RFLP analysis of mitochondrial cytochrome c oxidase subunit 1 gene (mtCOI) sequences of 621 whitefly individuals confirmed the presence of the Mediterranean (MED) type of the B. tabaci and of T. vaporariorum in most sampled regions. Also, individuals of the Middle East-Asia Minor 1 (MEAM1) type of the B. tabaci were observed in low numbers. Contingency analyses based on type of crop, geographical region, whitefly species, year of collection and production system confirmed that T. vaporariorum was the most frequent species in vegetable production areas in Costa Rica, both in greenhouses and in open fields. B. tabaci MED is likely spreading to new areas of the country, whereas B. tabaci MEAM1 was mostly absent or rarely found. Comparisons of mtCOI sequences from B. tabaci individuals revealed the presence of four B. tabaci sequence haplotypes (named MED-i, MED-ii, MEAM1-i, MEAM1-xviii) in Costa Rica, three of them identical to B. tabaci haplotypes previously reported in the Western Hemisphere and other parts of the world. Analysis of sequences of T. vaporariorum individuals revealed a more complex population with the presence of 11 haplotypes, two of which were identical to T. vaporariorum sequences reported from other countries.National Council for Scientific and Technological Development/[]/CNPq/BrasilUniversidad de Costa Rica/[801-B1-650]/UCR/Costa RicaMinisterio de Economía y Competitividad/[]//EspañaMinisterio de Economía, Industria y Competitividad/[]//EspañaEuropean Regional Development Fund/[]/ERDF/Unión EuropeaEuropean Social Fund/[AGL2016-75819-C2-2]/ESF/Unión EuropeaCITAUCR::Vicerrectoría de Investigación::Unidades de Investigación::Ciencias Agroalimentarias::Centro Nacional de Ciencia y Tecnología de Alimentos (CITA)CIBCMUCR::Vicerrectoría de Docencia::Ciencias Agroalimentarias::Facultad de Ciencias Agroalimentarias::Escuela de Tecnología de AlimentosUCR::Vicerrectoría de Investigación::Unidades de Investigación::Ciencias Agroalimentarias::Centro de Investigación en Protección de Cultivos (CIPROC)UCR::Vicerrectoría de Docencia::Ciencias Agroalimentarias::Facultad de Ciencias Agroalimentarias::Escuela de Agronomí
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