146 resultados para bicycles


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Increasing the modal share of public transit systems has become paramount in aiding the reduction on the excessive reliance of personal motor vehicles. More so the need to increase the share of active modes of transport such as the use of bicycles, therefore there is an ever increasing need to use bicycles both on shared pedestrian paths and on-road cycling. The risk to cyclist, or consequently the perception of the risk from both cyclists and motorists alike, is an important factor to increase the use of this transport mode. This paper investigates perception of bicycle safety by conducting a survey and analysing the survey data to understand how participants with different backgrounds perceive the risks of cycling for transport. Contributing factors to people’s perception of bicycle safety were identified and compared across different road user groups, based upon which recommendations were made on how to improve bicycle safety.

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There are currently more than 700 cities operating bike share programs. Purported benefits of bike share include flexible mobility, physical activity, reduced congestion, emissions and fuel use. Implicit or explicit in the calculation of program benefits are assumptions regarding the modes of travel replaced by bike share journeys. This paper examines the degree to which car trips are replaced by bike share, through an examination of survey and trip data from bike share programs in Melbourne, Brisbane, Washington, D.C., London, and Minneapolis/St. Paul. A secondary and unique component of this analysis examines motor vehicle support services required for bike share fleet rebalancing and maintenance. These two components are then combined to estimate bike share’s overall contribution to changes in vehicle kilometers traveled. The results indicate an estimated reduction in motor vehicle use due to bike share of approx. 90,000 km per annum in Melbourne and Minneapolis/St. Paul and 243,291 km for Washington, D.C. London’s bike share program however recorded an additional 766,341 km in motor vehicle use. This was largely due to a low car mode substitution rate and substantial truck use for rebalancing of bicycles. As bike share programs mature, evaluation of their effectiveness in reducing car use may become increasingly important. Researchers can adapt the analytical approach proposed in this paper to assist in the evaluation of current and future bike share programs.

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Over recent years, the health, transport and environment sectors have been increasingly focused on the promotion of transport cycling. From a health perspective, transport cycling is recognised as a beneficial form of physical activity as it can be easily integrated into daily living, is done at an intensity that confers health benefits, and is associated with reductions in mortality and morbidity [1]. From a safety perspective, the risk of a serious cycling injury decreases as cycling increases [2] as having more cyclists on roads increases motor vehicle drivers’ awareness of cyclists and in turn makes cycling safer. Whereas cycling for recreation is the fourth most commonly reported physical activity among Australian adults [3], transport cycling is an underutilised travel mode. Approximately 1.3% of journeys to work in Australia are made by bicycle [4]. This low prevalence is mirrored in the UK and the US, but not in some European countries like the Netherlands and Denmark, where over 18% and 26%, respectively, of all journeys are made by bicycle [5]. In the past decade, concerted efforts have been made by Australian state and local governments to increase cycling rates [6]. Notably, Melbourne, Sydney and Brisbane have implemented policies, increased bicycle commuting infrastructure, and offered information and promotion programs to encourage commuter cycling [6,7]. Governments have also developed comprehensive longterm plans for guiding future cycling strategies, using lessons learned from around the world in developing successful cycling policy and promotion [6,7]. Changes in transport cycling rates in inner cities since these efforts have been implemented are encouraging. In Sydney, census data indicate an 83% increase in the number of people using a bicycle for commuting between 2001 and 2011 [8]. Counts of bicycles being ridden along major cycling commuter routes indicate increases in weekday morning cycling trips in Brisbane (63% increase from 2004 to 2010) [7] and in Melbourne (a 43% increase from 2006 to 2008) [9]. However, bicycle mode share to work has changed little: for example, between 2001 and 2011, it decreased slightly from 1.6% to 1.3% in Brisbane [10,11]. Researchers have been investigating factors that may be contributing to low rates of cycling for transport, to inform future policy and programming to encourage transport cycling. The aim of this paper is to overview our work to date in this area of research in Queensland.

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Purpose Optical blur and ageing are known to affect driving performance but their effects on drivers' eye movements are poorly understood. This study examined the effects of optical blur and age on eye movement patterns and performance on the DriveSafe slide recognition test which is purported to predict fitness to drive. Methods Twenty young (27.1 ± 4.6 years) and 20 older (73.3 ± 5.7 years) visually normal drivers performed the DriveSafe under two visual conditions: best-corrected vision and with +2.00 DS blur. The DriveSafe is a Visual Recognition Slide Test that consists of brief presentations of static, real-world driving scenes containing different road users (pedestrians, bicycles and vehicles). Participants reported the types, relative positions and direction of travel of the road users in each image; the score was the number of correctly reported items (maximum score of 128). Eye movements were recorded while participants performed the DriveSafe test using a Tobii TX300 eye tracking system. Results There was a significant main effect of blur on DriveSafe scores (best-corrected: 114.9 vs blur: 93.2; p < 0.001). There was also a significant age and blur interaction on the DriveSafe scores (p < 0.001) such that the young drivers were more negatively affected by blur than the older drivers (reductions of 22% and 13% respectively; p < 0.001): with best-corrected vision, the young drivers performed better than the older drivers (DriveSafe scores: 118.4 vs 111.5; p = 0.001), while with blur, the young drivers performed worse than the older drivers (88.6 vs 95.9; p = 0.009). For the eye movement patterns, blur significantly reduced the number of fixations on road users (best-corrected: 5.1 vs blur: 4.5; p < 0.001), fixation duration on road users (2.0 s vs 1.8 s; p < 0.001) and saccade amplitudes (7.4° vs 6.7°; p < 0.001). A main effect of age on eye movements was also found where older drivers made smaller saccades than the young drivers (6.7° vs 7.4°; p < 0.001). Conclusions Blur reduced DriveSafe scores for both age groups and this effect was greater for the young drivers. The decrease in number of fixations and fixation duration on road users, as well as the reduction in saccade amplitudes under the blurred condition, highlight the difficulty experienced in performing the task in the presence of optical blur, which suggests that uncorrected refractive errors may have a detrimental impact on aspects of driving performance.

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BACKGROUND The workgroup of Traffic Psychology is concerned with the social, behavioral, and perceptual aspects that are associated with use and non-use of bicycle helmets, in their various forms and under various cycling conditions. OBJECTIVES The objectives of WG2 are to (1) share current knowledge among the people already working in the field, (2) suggest new ideas for research on and evaluation of the design of bicycle helmets, and (3) discuss options for funding of such research within the individual frameworks of the participants. Areas for research include 3.1. The patterns of use of helmets among different users: children, adults, and sports enthusiasts. 3.2. The use of helmets in different environments: rural roads, urban streets, and bike trails. 3.3. Concerns bicyclists have relative to their safety and convenience and the perceived impact of using helmets on comfort and convenience. 3.4. The benefit of helmets for enhancing visibility, and how variations in helmet design and colors affect daytime, nighttime, and dusktime visibility. 3.5. The role of helmets in the acceptance of city-wide pickup-and-drop-off bicycles. 3.6. The impact of helmets on visual search behaviour of bicyclists.

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This paper presents some results from preliminary analyses of the data of an international online survey of bicycle riders, who reported riding at least once a month. On 4 July 2015, data from 7528 participants from 17 countries was available in the survey, and were subsequently cleaned and checked for consistency. The median distance ridden ranged from 30 km/week in Israel to 150 km/week in Greece (overall median 54 km/week). City/hybrid bicycles were the most common type of bicycle ridden (44%), followed by mountain (20%) and road bikes (15%). Almost half (47%) of the respondents rode “nearly daily”. About a quarter rode daily to work or study (27%). Overall, 40% of respondents reported wearing a helmet ‘always’, varying from 2% in the Netherlands to 80% in Norway, while 25% reported ‘never’ wearing a helmet. Thus, individuals appeared to consistently either use or not use helmets. Helmet wearing rates were generally higher when riding for health/fitness than other purposes and appeared to be little affected by the type of riding location, but some divergences in these patterns were found among countries. Almost 29% of respondents reported being involved in at least one bicycle crash in the last year (ranging from 12% in Israel to 53% in Turkey). Among the most severe crashes for each respondent, about half of the crashes involved falling off a bicycle. Just under 10% of the most severe crashes for each respondent were reported to police. Among the bicycle-motor vehicle crashes, only a third were reported to police. Further analyses will address questions regarding the influence of factors such as demographic characteristics, type of bicycle ridden, and attitudes on both bi-cycle use and helmet wearing rates.

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In my job I see many students who have not learned to write a technical paper. When they do competent work, I want them to be able to write passable reports. This article is for them. There are well established principles for citing the relevant work of others; for not copying things without giving credit; for not stealing. If a reader feels you have copied anything, a figure, even a phrase, from elsewhere without citing its source, then you are guilty of plagiarism in the eyes of that reader. Committing plagiarism is so bad that I cannot do justice to it here. So I merely say: never do it. On, then, to writing your own honest and original material. Art requires talent. In contrast, through discipline and persistence alone, you can learn how to differentiate functions and ride bicycles. Similarly, you can write a passable technical paper. You just have to realize that your job does not end with research. Writing a passable paper involves extra work.

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OBJECTIVE: To study the effect of myopia and spectacle wear on bicycle-related injuries in rural Chinese students. Myopia is common among Chinese students but few studies have examined its effect on daily activities. METHODS: Data on visual acuity, refractive error, current spectacle wear, and history of bicycle use and accidents during the past 3 years were sought from 1891 students undergoing eye examinations in rural Guangdong province. RESULTS: Refractive and accident data were available for 1539 participants (81.3%), among whom the mean age was 14.6 years, 52.5% were girls, 26.8% wore glasses, and 12.9% had myopia of less than -4 diopters in both eyes. More than 90% relied on bicycles to get to school daily. A total of 2931 accidents were reported by 423 participants, with 68 requiring medical attention. Male sex (odds ratio, 1.55; P < .001) and spectacle wear (odds ratio, 1.38; P = .04) were associated with a higher risk of accident, but habitual visual acuity and myopia were unassociated with the crash risk, after adjusting for age, sex, time spent riding, and risky riding behaviors. CONCLUSION: These results may be consistent with data on motor vehicle accidents implicating peripheral vision (potentially compromised by spectacle wear) more strongly than central visual acuity in mediating crash risk.

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Fahrradfahren ist für viele Menschen ein wichtiger Mobilitätsfaktor. Sie können sich mit eigener Kraft in einem Umkreis von mehreren Kilometern bewegen. Im Alter wird das Fahrradfahren jedoch durch nachlassende Kraft und eingeschränkte Motorik zum Gleichgewichthalten eingeschränkt. Erschwerend kommt hinzu, dass diese Personen aus Vorsicht in der Regel kleinere Fahrgeschwindigkeiten bevorzugen. Bei niedrigen Geschwindigkeiten nimmt aber die Gleichgewichtsstabilität des Fahrrads ab und der Fahrer muss intensiver mit dem Lenker das Gleichgewicht kontrollieren. Moderne E-Bikes können die nachlassende körperliche Kraft kompensieren. Es bleibt aber das Problem des Gleichgewichthaltens beim Radfahren. Im folgenden Beitrag wird die Gleichgewichtsregelung von Fahrädern betrachtet. Dabei werden verschiedene Möglichkeiten der Gleichgewichtsregelung behandelt. Die Beurteilung der Verfahren erfolgt anhand der Stabilität und der Eigenschwingungen des geregelten Systems. Besonderes Augenmerk wird dabei auf die Stabilisierung des Bereichs geringer Fahrgeschwindigkeiten gelegt, da mit der nachlassenden Motorik oft auch eher geringere Fahrgeschwindigkeiten gewählt werden.

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Trabalho Final de Mestrado para obtenção do grau de Mestre em Engenharia Civil

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Durch asymmetrische Doppelbindungsisomerisierung mittels Me-DuPHOS-modifizierter Dihalogen-Nickel-Komplexe als Katalysatorvorstufen lassen sich aus 2-Alkyl-4,7-dihydro-1,3-dioxepinen hochenantiomerenreine 2-Alkyl-4,5-dihydro-1,3-dioxepine erhalten. Ein Ziel dieser Arbeit war es, die bisher noch unbekannte Absolutkonfiguration dieses Verbindungstyps zu bestimmen und darüber hinaus ihre Einsatzfähigkeit in der enantioselektiven organischen Synthese zu untersuchen. Zu diesem Zweck wurden enantiomerenangereichertes 2-Isopropyl- und 2-tert-Butyl-4,5-dihydro-1,3-dioxepin mit m-Chlorperbenzoesäure epoxidiert. Dabei bildeten sich die entsprechenden 3-Chlorbenzoesäure-(2-alkyl-5-hydroxy-1,3-dioxepan-4yl)-ester in hohen Ausbeuten und Diastereoselektivitäten. Von den vier zu erwartenden Diastereomeren wurden jeweils nur zwei mit einer Selektivität von mehr als 95:5 gebildet. Im Fall des 3-Chlorbenzoesäure-(2-isopropyl-5-hydroxy-1,3-dioxepan-4yl)-esters konnte das Haupt-diastereomer kristallin erhalten werden. Durch röntgenspektroskopische Untersuchung war es möglich, die Relativ-Konfiguration dieser Verbindung zu bestimmen. Die Ester lassen sich unter Ringverengung in 2-Alkyl-1,3-dioxan-4-carbaldehyde umlagern. Ausgehend von diesen Carbaldehyden stehen zwei Synthesewege zur Verfügung, welche zu Verbindungen führen deren Absolutkonfiguration bereits bekannt ist. So erhält man durch Reduktion 2-Alkyl-1,3-dioxan-4-yl-methanole, welche sich in 1,2,4-Butantriol überführen lassen. Oxidation ergibt die 2-Alkyl-1,3-dioxan-4-carbonsäuren, aus denen 3-Hydroxytetrahydrofuran-2-on gewonnen werden kann. Messung des Drehwertes dieser beiden literaturbekannten Verbindungen liefert nicht nur Information über deren Enantiomerenreinheit sondern ebenfalls über die Konfiguration ihres Stereozentrums. In Kombination mit der Relativ-Konfiguration des Esters ist somit ein Rückschluss auf die Absolutkonfiguration der eingesetzten 4,5-Dihydro-1,3-dioxepine möglich. Die auf den beschriebenen Wegen gewonnenen Substanzen finden Anwendung in der stereoselektiven organischen Synthese. Löst man die Chlorbenzoesäureester in Dichlormethan und behandelt sie mit wässriger Salzsäure, so entstehen die bicyclischen 2-Alkyltetrahydrofuro[2,3-d][1,3]dioxole. Auch bei diesen Verbindungen konnten hohe Enantio- und Diastereoselektivitäten erzielt werden. Der intermolekular verlaufende Reaktionsmechanismus der Bicyclus-Bildung, welcher unter Abspaltung eines den Alkylrest tragenden Aldehyds und dessen Neuanlagerung unter Ausbildung eines Acetals verläuft, konnte in dieser Arbeit durch ein Kreuzungsexperiment bestätigt werden. Umacetalisierung der Bicyclen liefert 2-Methoxytetrahydrofuran-3-ol, aus dem durch Acetalspaltung Tetrahydrofuran-2,3-diol erhalten wird, das die Halbacetalform der entsprechenden Desoxytetrose darstellt, die auf diese Weise in einer de novo-Synthese hergestellt werden kann.

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L' objectiu d' aquest projecte és crear un sistema de càlcul per estudiar el desplaçament dels amortidors al llarg del cicle de pedalada, que són la causa de la dissipació d' energia. Tot el projecte s' ha desenvolupat de forma teòrica i l' estudi que s' ha dut a terme ha estat estàtic. Els resultats obtinguts són una aproximació del que seria de s' hagués estudiat dinàmicament

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Disseny complet d’una bicicleta per a nens i nenes de 6 a 11 anys del continent africà. L’ús de la bicicleta està pensat inicialment per als infants que pateixen llargs desplaçaments per anar a l’escola, tot i que pot tenir altres usos com, per exemple, el lúdic. Fonamentalment la bicicleta ha de ser el màxim de simple, econòmica i sostenible possible. Ha de ser duradora i fiable i tenir els mínims components. Aquest projecte només contempla el disseny i la fabricació de la bicicleta a Europa per a ser enviada posteriorment

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Objetivo. Describir factores sociodemográficos, ocupacionales y extraocupacionales en un grupo de trabajadores tejedores del área de circulares, quienes operan máquinas marca Monarch en una Empresa Textil en Bogotá entre Octubre 2011 y Junio de 2012. Materiales y Métodos: Estudio descriptivo. La población fueron trabajadores tejedores mayores de edad que presentan lesiones osteomusculares, que operan máquinas MONARCH en el Área de Circulares de una Empresa Textil en Bogotá. De 300 trabajadores, 150 presentaron síntomas, 94 cumplieron criterios de inclusión. Resultados: La edad mediana fue 41 años. La mayoría fue sexo masculino. La mayoría estuvo en el mismo cargo 6-10 años. Menos de la mitad reportó realizar actividad física y la mayoría tenía estado nutricional normal. La minoría consumía cigarrillo. Se encontró que el 68.1% presentó dolor lumbar. Se presentó en 72% una lesión osteomuscular. El dolor lumbar fue más frecuente entre 31-45 años. Conclusiones: La lesión osteomuscular más frecuente fue dolor lumbar. Se presentó con mayor frecuencia una sola lesión osteomuscular. La población no es homogénea lo que puede ser un sesgo para los resultados obtenidos para edad y presencia de lesiones osteomusculares. Los trabajadores realizaban actividad física en 40.9% ya usan bicicleta como medio de transporte. No se pudo establecer relación entre estado nutricional y lesiones osteomusculares. Los trabajadores desempeñan actividades que requieren posturas, manipulación de carga y movimientos repetitivos que son constantes en un mismo cargo lo que pude estar relacionado con presencia de lesiones osteomusculares. Sería importante realizar estudios que determinen factores protectores y de riesgo.

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El texto muestra la evolución del componente destinado a incentivar el uso de la bicicleta en el marco de la política de movilidad de Bogotá desde Mockus hasta Petro y también el papel de la sociedad civil en el proceso de la reimplementación de dicho componente en la alcaldía de Moreno y en la de Petro.