Bibliometric analysis of simulated driving research from 1997 to 2016

Objective: The objective of this study was to explore the evolution footprints of simulated driving research in the past 20 years through rigorous and systematic bibliometric analysis, to provide insights regarding when and where the research was performed and by whom and how the mainstream content evolved over the years.

Methods: The analysis began with data retrieval in Web of Science with defined search terms related to simulated driving. BibExcel and CiteSpace were employed to conduct the performance analysis and co-citation network analysis; that is, probe of the performance of institutes, journals, authors, and research hotspots.

Results: A total of 3,766 documents were filtered out and presented an exponential growth from 1997 to 2016. The United States contributed the most publications as well as international collaborations followed by Germany and China. In addition, several universities in The Netherlands and the United States dominated the list of contributing institutes. The leading journals were in transportation and ergonomics. The leading researchers were also recognized among the 8,721 contributing authors, such as J. D. Lee, D. L. Fisher, J. H. Kim, and K. A. Brookhuis. Finally, the co-citation analysis illuminated the evolution of simulated driving research that covered the following topics roughly in chronological order: task-induced stress, drivers with neurological disorders, alertness and sleepiness while driving, trust toward driving assistance systems, driver distraction, the effect of drug use, the validity of simulators, and automated driving.

Conclusions: This article employed bibliometric tools to probe the contributing countries, institutes, journals, authors, and mainstream hotspots of simulated driving research in the past 20 years. A systematic bibliometric analysis of this field will help researchers realize the panorama of global simulated driving and establish future research directions.     

Sensitivity analysis of a parameterization of the stomatal component of the DO3SE model for Quercus ilex to estimate ozone fluxes

A sensitivity analysis of a proposed parameterization of the stomatal conductance (g(s)) module of the European ozone deposition model (DO(3)SE) for Quercus ilex was performed. The performance of the model was tested against measured g(s) in the field at three sites in Spain. The best fit of the model was found for those sites, or during those periods, facing no or mild stress conditions, but a worse performance was found under severe drought or temperature stress, mostly occurring at continental sites. The best performance was obtained when both f(phen) and f(SWP) were included. A local parameterization accounting for the lower temperatures recorded in winter and the higher water shortage at the continental sites resulted in a better performance of the model. The overall results indicate that two different parameterizations of the model are needed, one for marine-influenced sites and another one for continental sites.     

Precision teaching to improve drivers’ lane maintenance

Introduction: This study investigates the effect of precision teaching signals on lane maintenance. Methods: In experiment 1, the control group drove a simulator with no signals. In experiment 2, drivers were presented with auditory signals depending on their position within or outside the lane. In experiment 3, visual signals were presented in addition to auditory signals to examine the effect of redundancy on drivers’ lane maintenance. Results: Results showed an improvement in lane maintenance in experiment 2. Cross-experiment analysis indicated this effect not to be the result of learning. Data from experiment 3 also showed that presenting redundant signals did not further reduce lane variability or help drivers maintain a more central position within the lane. Conclusions: Taken together, data suggest precision teaching be effective as an educational tool to improve lane maintenance. Practical Applications: Our study shows the potential for precision teaching to serve as a valuable tool in driver training.     

Effects of alcohol at 0.05% blood alcohol concentration (BAC) on low speed urban driving

ABSTRACT

Objective: Alcohol-impaired driving presents a continued risk for traffic safety and results in a significant proportion of fatalities on the roadway. We examined how alcohol at a 0.05% blood alcohol concentration (BAC) compares to 0.10% BAC (above the current U.S. legal limit) in terms of impact on driving performance.

Methods: Utilizing a within-subjects design, we recruited 108 healthy experienced drivers who were moderate to heavy drinkers. In a double-blind, placebo-controlled crossover design, we administered placebo and alcohol at the 0.05% and 0.10% BAC levels in a standardized simulated driving protocol. Drives occurred on the descending limb of the blood alcohol curve. This analysis focuses on the urban portion of the drive

Results: The study observed clear differences in performance for lateral and longitudinal driving performance and glance behavior. Variability in lane keeping and average speed increased with BAC level, with degraded performance observed at 0.05% BAC. The frequency of lane departures and percentage of time focused on the forward roadway at 0.05% BAC did not differ from placebo but differed from the 0.10% BAC level.

Conclusions: Overall, our results show that there is degraded performance in the urban driving environment and that much of that begins at or below the 0.05% BAC level.     

Structural equation model analysis for the evaluation of overall driving performance: A driving simulator study focusing on driver distraction

Objective: The present research relies on 2 main objectives. The first is to investigate whether latent model analysis through a structural equation model can be implemented on driving simulator data in order to define an unobserved driving performance variable. Subsequently, the second objective is to investigate and quantify the effect of several risk factors including distraction sources, driver characteristics, and road and traffic environment on the overall driving performance and not in independent driving performance measures.

Methods: For the scope of the present research, 95 participants from all age groups were asked to drive under different types of distraction (conversation with passenger, cell phone use) in urban and rural road environments with low and high traffic volume in a driving simulator experiment. Then, in the framework of the statistical analysis, a correlation table is presented investigating any of a broad class of statistical relationships between driving simulator measures and a structural equation model is developed in which overall driving performance is estimated as a latent variable based on several individual driving simulator measures.

Results: Results confirm the suitability of the structural equation model and indicate that the selection of the specific performance measures that define overall performance should be guided by a rule of representativeness between the selected variables. Moreover, results indicate that conversation with the passenger was not found to have a statistically significant effect, indicating that drivers do not change their performance while conversing with a passenger compared to undistracted driving. On the other hand, results support the hypothesis that cell phone use has a negative effect on driving performance. Furthermore, regarding driver characteristics, age, gender, and experience all have a significant effect on driving performance, indicating that driver-related characteristics play the most crucial role in overall driving performance.

Conclusions: The findings of this study allow a new approach to the investigation of driving behavior in driving simulator experiments and in general. By the successful implementation of the structural equation model, driving behavior can be assessed in terms of overall performance and not through individual performance measures, which allows an important scientific step forward from piecemeal analyses to a sound combined analysis of the interrelationship between several risk factors and overall driving performance.     

建筑火灾烟气中CO迁移规律的FDS模拟

以T型"侧间-走廊"典型建筑火灾为模拟对象,分析烟气在走廊中的水平和垂直流动特征,并对火源房门高低、走廊端头启闭和多房门启闭等场景使用火灾模拟软件(FDS)进行了模拟和远距离房间CO浓度的迁移规律的分析。结果表明:烟气从火源房间经拱腹溢出在走廊中形成受限空间的顶棚射流;门檐高度决定了CO能够在走廊中的迁移量;烟气在走廊远距离封闭端头形成上部的热烟气层,中部回流层和下层的补气层;其中中部烟气回流层的高低、流速和CO浓度是影响临近非火源房间CO浓度的重要因素。走廊启闭和多房门火灾场景的模拟结果也进一步证明了CO的迁移规律。     

Defining Historical Baselines for Conservation: Ecological Changes Since European Settlement on Vancouver Island,Canada

Abstract: Conservation and restoration goals are often defined by historical baseline conditions that occurred prior to a particular period of human disturbance, such as European settlement in North America. Nevertheless, if ecosystems were heavily influenced by native peoples prior to European settlement, conservation efforts may require active management rather than simple removal of or reductions in recent forms of disturbance. We used pre‐European settlement land survey records (1859–1874) and contemporary vegetation surveys to assess changes over the past 150 years in tree species and habitat composition, forest density, and tree size structure on southern Vancouver Island and Saltspring Island, British Columbia, Canada. Several lines of evidence support the hypothesis that frequent historical burning by native peoples, and subsequent fire suppression, have played dominant roles in shaping this landscape. First, the relative frequency of fire‐sensitive species (e.g., cedar [Thuja plicata]) has increased, whereas fire‐tolerant species (e.g., Douglas‐fir [Pseudotsuga menziesii]) have decreased. Tree density has increased 2‐fold, and the proportion of the landscape in forest has greatly increased at the expense of open habitats (plains, savannas), which today contain most of the region's threatened species. Finally, the frequency distribution of tree size has shifted from unimodal to monotonically decreasing, which suggests removal of an important barrier to tree recruitment. In addition, although most of the open habitats are associated with Garry oak (Quercus garryana) at present, most of the open habitats prior to European settlement were associated with Douglas‐fir, which suggests that the current focus on Garry oak as a flagship for the many rare species in savannas may be misguided. Overall, our results indicate that the maintenance and restoration of open habitats will require active management and that historical records can provide critical guidance to such efforts.     

Distribution and persistence of carbaryl in some terrestrial and aquatic components of a forest environment

Abstract

An oil‐based formulation of carbaryl (1‐naphthyl N‐methyl‐carbamate) (Sevin‐2‐Oil) was applied twice by a fixed‐wing aircraft at a dosage rate of 280 g of A.I./ha/application to a coniferous forest near Allardville, New Brunswick. The highest concentrations of the chemical in fir foliage, litter and forest soil 1 h after application were respectively 4.20, 1.21 and 0.59 ppm (fresh weight). The residues dissipated rapidly and the DT50 values obtained from the depletion curves were 2.3 d for foliage and 1.5 d for litter and soil samples. Very low levels (<0.1 ppm) of carbaryl persisted in foliage and litter beyond the 10 d sampling period. The maximum residue level found in stream water was 0.314 ppm and more than 50% of it had dissipated within 1 h. Low but detectable levels (0.001 ppm) of the chemical persisted in water until the end of the 10 d sampling period. Sediment samples contained a maximum level of 0.04 ppm, which dissipated below the detection limit within 5 h. Brook trout and slimy sculpins captured in the stream 1 d after the spray contained on average about 0.04 ppm of carbaryl and none of it was found in 3 d postspray samples.     

Rain‐washing of foliar deposits of Dimilin®WP‐25 formulated in four different carrier liquids

Abstract

Dimilin^® WP‐25, a wettable powder formulation of diflubenzuron (DFB) [1‐(4‐chlorophenyl)‐3‐(2,6‐difluorobenzoyl) urea], was formulated in four different carrier liquids, viz., water; a light petroleum paraffinic oil, ID 585; a heavy paraffinic oil, Sunspray^® 7N; and a 1:2 mixture of a light petroleum aromatic solvent (Cyclosol^® 63) and canola oil; to provide four end‐use mixtures, Dim‐W, Dim‐585, Dim‐7N and Dim‐Cy‐C respectively, each containing 28 g of DFB per litre. Balsam fir branch tips clipped from greenhouse‐grown seedlings, and sugar maple branch tips clipped from field‐grown young trees, were exposed to uniform‐sized droplets (ranging in diameters from 135 to 190 μm) of the four end‐use mixtures which were atomized using a monodispersed droplet generator. Droplets were collected on the fir and maple branch tips and the initial residue per g fresh weight of foliage was determined by high‐performance liquid chromatography (HPLC). The branch tips were exposed to cumulative rainfall of 3, 6 and 10 mm at an intensity of 5 mm/h and at time intervals of 1, 12, 36 and 72 h after DFB treatment, to test the influence of ‘ageing’ of foliar residues on rainfastness. Foliar samples were collected for residue determination just before the onset of rainfall, and at 0.5 h post‐rain. DFB was quantified by the HPLC method. In the case of fir foliage, the Dim‐W formulation was the most susceptible to rain‐washing and the rainfastness did not increase with the ageing period of foliar deposits. In contrast, the three oil‐based mixtures showed greater rainfastness depending upon the carrier liquid and the ageing period. Rainfastness decreased in the order of Dim‐Cy‐C > Dim‐7N > Dim‐585 > Dim‐W. In contrast, the data on maple foliage indicated that the ageing of deposits increased the rainfastness of all the 4 end‐use mixtures. Dim‐585 was the most susceptible to rain washing, and rainfastness decreased in the order of Dim‐W > Dim‐Cy‐C > Dim‐7N > Dim‐585.     

Traditional Land-Use Systems and Patterns of Forest Fragmentation in the Highlands of Chiapas, Mexico

The influence of slash-and-burn agriculture and tree extraction on the spatial and temporal pattern of forest fragmentation in two municipalities in the highlands of Chiapas, Mexico was analyzed. The data series were derived from two subsets of satellite images taken in 1974 and 1996. The analysis was based on area, edge, shape, core area, and neighbor indices. During the 22 years, the dense forest decreased by 8.9%/yr in Huistán and by 8.6%/yr in Chanal, while open/disturbed forest, secondary vegetation, and developed area increased in both municipalities. The total number of fragments increased by 1.4%/yr and 2.3%/yr in Huistán and Chanal, respectively. Dense forest showed the highest increase in the number of fragments (6%/yr in Huistán and 12%/yr in Chanal), while edge length, core area, and number of dense forest core areas decreased. The larger fragments of dense forest present in 1974 were divided into smaller fragments in 1996; at the same time, they experienced a process of degradation toward open/disturbed forest and secondary vegetation. Two different fragmentation patterns could be distinguished based on agricultural or forestry activities. Forest fragmentation did not occur as a continuous process; the pattern and degree of fragmentation were functions of land tenure, environmental conditions, and productive activities. The prevalence of rather poor soil conditions, small-holdings, growing human population densities, increasing poverty, and the absence of alternative economic options will maintain a high rate of deforestation and forest fragmentation in the studied region.