Industry and Society 10/1974 12 March 1974

Lane changing is one of the most common maneuvers on motorways. Although, macroscopic traffic models are well known for their suitability to describe fast moving crowded traffic, most of these models are generally developed in one dimensional framework, henceforth lane changing behavior is somehow neglected. In this paper, we propose a macroscopic model, which accounts for lane-changing behavior on motorway, based on a two-dimensional extension of the Aw and Rascle [Aw and Rascle, SIAM J.Appl.Math., 2000] and Zhang [Zhang, Transport.Res.B-Meth., 2002] macroscopic model for traffic flow. Under conditions, when lane changing maneuvers are no longer possible, the model "relaxes" to the one-dimensional Aw-Rascle-Zhang model. Following the same approach as in [Aw, Klar, Materne and Rascle, SIAM J.Appl.Math., 2002], we derive the two-dimensional macroscopic model through scaling of time discretization of a microscopic follow-the-leader model with driving direction. We provide a detailed analysis of the space-time discretization of the proposed macroscopic as well as an approximation of the solution to the associated Riemann problem. Furthermore, we illustrate some features of the proposed model through some numerical experiments.Comment: 26 page

Crash risk by driver age, gender, and time of day using a new exposure methodology

Introduction: Concerns have been raised that the nonlinear relation between crashes and travel exposure invalidates the conventional use of crash rates to control for exposure. A new metric of exposure that bears a linear association to crashes was used as basis for calculating unbiased crash risks. This study compared the two methods – conventional crash rates and new adjusted crash risk – for assessing the effect of driver age, gender, and time of day on the risk of crash involvement and crash fatality. Method: We used police reports of single-car and multi-car crashes with fatal and nonfatal driver injuries that occurred during 2002–2012 in Great Britain. Results: Conventional crash rates were highest in the youngest age group and declined steeply until age 60–69 years. The adjusted crash risk instead peaked at age 21–29 years and reduced gradually with age. The risk of nighttime driving, especially among teenage drivers, was much smaller when based on adjusted crash risks. Finally, the adjusted fatality risk incurred by elderly drivers remained constant across time of day, suggesting that their risk of sustaining a fatal injury due to a crash is more attributable to excess fragility than to crash seriousness. Conclusions: Our findings demonstrate a biasing effect of low travel exposure on conventional crash rates. This implies that conventional methods do not yield meaningful comparisons of crash risk between driver groups and driving conditions of varying exposure to risk. The excess crash rates typically associated with teenage and elderly drivers as well as nighttime driving are attributed in part to overestimation of risk at low travel exposure. Practical Applications: Greater attention should be directed toward crash involvement among drivers in their 20s and 30s as well as younger drivers. Countermeasures should focus on the role of physical vulnerability in fatality risk of elderly drivers

What are the factors that contribute to road accidents? An assessment of law enforcement views, ordinary drivers’ opinions, and road accident records

What are the main contributing factors to road accidents? Factors such as inexperience, lack of skill, and risk-taking behaviors have been associated with the collisions of young drivers. In contrast, visual, cognitive, and mobility impairment have been associated with the collisions of older drivers. We investigated the main causes of road accidents by drawing on multiple sources: expert views of police officers, lay views of the driving public, and official road accident records. In Studies 1 and 2, police officers and the public were asked about the typical causes of road traffic collisions using hypothetical accident scenarios. In Study 3, we investigated whether the views of police officers and the public about accident causation influence their recall accuracy for factors reported to contribute to hypothetical road accidents. The results show that both expert views of police officers and lay views of the driving public closely approximated the typical factors associated with the collisions of young and older drivers, as determined from official accident records. The results also reveal potential underreporting of factors in existing accident records, identifying possible inadequacies in law enforcement practices for investigating driver distraction, drug and alcohol impairment, and uncorrected or defective eyesight. Our investigation also highlights a need for accident report forms to be continuously reviewed and updated to ensure that contributing factor lists reflect the full range of factors that contribute to road accidents. Finally, the views held by police officers and the public on accident causation influenced their memory recall of factors involved in hypothetical scenarios. These findings indicate that delay in completing accident report forms should be minimised, possibly by use of mobile reporting devices at the accident scene

The Process of Analyzing Data is the Emergent Feature of Data Science

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Determination Contents of Total Phenolic Pigments and Spectrophotometric Characterization of Crude Extracts of Ten Tinctorial Plants of Niger which is Usable in Solar Energy

Dye Sensitized-Solar Cells (DSSCs) have been extensively investigated because of their environmental friendliness and low production cost. At the heart of these is the photosensitive pigment that plays a key role in the collection of sunlight radiations and its conversion into electrical energy. However, the toxicity and the cost of pigment synthesis limit the increased use of these prototypes. Natural pigments can be an effective, sustainable, and inexpensive alternative. This paper focuses on determining the main phenolic pigments contents and evaluating the solar light collection capacity of ten (10) tinctorial plants crude extracts, via UV-Visible Spectrophotometry. High concentrations of total polyphenols (46.54 mgEqAG/g), flavonoids (10.95 mgEqQuer/g), anthocyanins (181.9 mgL-1 ), and tannins (40.1 mgL-1 ) were recorded in some extracts of these plants. Absorption spectra showed intense absorption domains around 280 nm in the ultraviolet (UV), and also in the visible (400 to 700 nm). These absorptions would be attributed to the π-π* and n-π* electron transitions of the chromophores present in the anthocyanin, flavonoid, carotenoid, and chlorophyll pigments of these plants. The high contents of pigments and the appropriate spectrophotochemical properties make the extracts of these tinctorial plants to become potential raw materials that are useful in solar energy technology

Stochastic analysis of seepage under water-retaining structures

This paper investigated the problem of confined flow under dams and water retaining structures using stochastic modelling. The approach advocated in the study combined a finite elements method based on the equation governing the dynamics of incompressible fluid flow through a porous medium with a random field generated hydraulic conductivity using a lognormal probability distribution. The resulting model was then used to analyse confined flow under a hydraulic structure. Cases for a structure provided with cutoff wall and when the wall did not exist were both tested. Various statistical parameters that reflected different degrees of heterogeneity were examined and the changes in the mean seepage flow, the mean uplift force and the mean exit gradient observed under the structure were analysed. Results reveal that under heterogeneous conditions, the reduction made by the sheetpile in the uplift force and exit hydraulic gradient may be underestimated when deterministic solutions are used

Caractérisation Phytochimique des Graines et des Pulpes de Lagenaria siceraria (Molina) Standley Utilisées en Pharmacopée dans Sept (6) Régions du Niger

As part of the valorization of medicinal plants in Niger, a phytochemical study was carried out on the seeds and pulp of the species Lagenaria siceraria (Molina) Standley harvested in six (6) regions. The objective was to perform a phytochemical characterization, determine their variability by region and determine the best extraction solvent. Thus, extraction with solvents of increasing polarities and phytochemical screening were carried out, using standard methods, on the various samples. The results obtained show that water is the best solvent for extracting phytocomposites from Lagenaria siceraria seeds and pulp. Extraction efficiency varies by region and solvent. Phytochemical triage tests, carried out on seeds and pulp, revealed the presence of alkaloids, saponosides, flavonoids, tannins, heterosides and an absence of leucoanthocyans, catechols and cyanidins in seed and pulp extracts from certain regions. These results could justify the traditional use of Lagenaria siceraria in the treatment of certain diseases.Dans le cadre de la valorisation des plantes médicinales du Niger, une étude phytochimique a été réalisée sur les graines et les pulpes de l’espèce Lagenaria siceraria (Molina) Standley récoltée dans six (6) régions. L’objectif était de faire une caractérisation phytochimique, de déterminer leur variabilité selon les régions et de déterminer le meilleur solvant d’extraction. Ainsi, une extraction avec des solvants de polarités croissantes et un screening phytochimique ont été effectués, avec des méthodes standards, sur les différents échantillons. Lesrésultats obtenus montrent que l’eau est le meilleur solvant d’extraction des phytocomposés de graines et pulpes de Lagenaria siceraria. Le rendement d’extraction varie selon les régions et en fonction des solvants. Les tests de tri phytochimiques, réalisés sur les graines et pulpes, ont révélés la présence des alcaloïdes, des saponosides, des flavonoïdes, des tanins, des hétérosides et une absence des leucoanthocyanes, des catéchols et des cyanidines dans les extraits de graine et pulpe de certaines régions. Ces résultats pourraient justifiés l’utilisation traditionnelle de Lagenaria siceraria dans le traitement de certaines maladies

Flore et Végétation de la Zone Centrale de l’Habitat de la Girafe au Niger, Afrique de l’Ouest

La présente étude analyse la flore et la végétation en lien avec les variables environnementales de la zone centrale de l’habitat de la girafe. Les relevés floristiques ont été réalisés dans 60 placettes de 1000 m² et 94 de 2500 m² à l’aide de la méthode de Braun-Blanquet. Au total 103 espèces végétales ont été recensées. Ces espèces sont reparties en 84 genres dans 43 familles botaniques dont la plus importante est celle des Poaceae (9 %), suivis par les Mimosaceae, les Caesalpiniaceae, les Combretaceae et les Papilionnaceae (6 % chacune). La Classification Hiérarchiques Ascendante a permis de distinguer quatre groupements végétaux au seuil de 74,76 % de similarité. Les variables environnementales comme la géomorphologie, la végétation, la texture du sol, l’altitude ont un effet significatif sur la distribution des espèces et la structuration de la végétation. On note aussi une prédominance des Thérophytes et des espèces à large distribution telles que les Paléotropicales et les Pantropicales dans les groupements. Ces résultats révèlent le degré d’exploitation de la végétation de la zone par les populations locales et l’aridité du climat sahélien.   This study analyzes the flora and vegetation in relation to the environmental variables of the central zone of the giraffe habitat. Floristic surveys were carried out in 60 plots of 1000 m² and 94 of 2500 m² using the Braun-Blanquet method. A total of 103 plant species have been recorded. These species are divided into 84 genera in 43 botanical families, the most important of which is Poaceae (9 %), followed by Mimosaceae, Caesalpiniaceae, Combretaceae and Papilionnaceae (6 % each). The Ascending Hierarchical Classification made it possible to distinguish four plant groups at the threshold of 74.76% similarity. Environmental variables such as geomorphology, vegetation, soil texture, altitude have a significant effect on the distribution of species and the structuring of vegetation. We also note a predominance of Therophytes and widely distributed species such as Paleotropicals and Pantropicals in the groupings. These results reveal the degree of exploitation of the vegetation in the area by local populations and the aridity of Sahelian climate